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1
Krysmann, Marta J. "Self-assembly of peptides and peptide based hybrids for therapeutic applications." Thesis, University of Reading, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.558793.
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A rich gallery of novel systems based on the sequence KLVFF (namely KLVFF, FFKLVFF, AAKLVFF, AAKLVAA, βAβAKLVFF, KLVFF-PEG, FFKLVFF-PEG, AAKLVFF-PEG, AAKLVAA-PEG, FF-PEG, FFFF-PEG) was synthesized and characterized. For the first time structure-properties relationships of this class of materials were systematically explored, with emphasis on self-association properties in both bulk and solution. Such a comparative investigation, essentially absent from the literature, provides insights into the underlying mechanism of amyloid fibrogenesis, given that KL VFF has been identified as critical for amyloid fibril formation of the amyloid-β peptide. In this respect, this virtually unique, bottom-up approach contributes to the development of therapeutics for Alzheimer's disease. Despite the fact that all the peptides were found to organize into predominantly β-sheet conformations (in a variety of solvents and in bulk) they exhibit a versatile range of morphological features, such as fibrils, twisted assemblies of protofilaments, hollow tubes and single tapes. Interestingly, FFKLVFF was found to exhibit strong fibrillization properties, while helically twisted ribbons were obtained from βAβAKL VFF. The self-organization of KLVFF towards fibrillar symmetries gives rise, under certain conditions, to time-dependant hydrogels with potential for application in tissue engineering. Notably, only FFKLVFF-PEG and FFFF-PEG retain the β-sheet conformation of the peptide precursor, and they form fibrils bearing a peptidic core surrounded by a corona of PEG chains. At high volume fractions packing of the FFKLVFF-PEG fibrils leads to the evolution of nematic and hexagonal columnar phases. Owing to their inherent biocompatible character, those hybrids carry great promise to substitute a number of conventional polymers in applications such as tissue engineering, cell growth and drug delivery. In the solid state, the interplay between two competing factors, polymer crystallization and peptide fibrillization, was studied for several conjugates. Two distinct cases were identified; solidification of FFKL VFF-PEG controlled by peptide- peptide interactions, while KLVFF -PEG and AAKL V AA-PEG crystals reflected the characteristics of PEG spherulites.
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Roberts, David John. "Peptide based conjugates for therapeutic delivery applications." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/peptide-based-conjugates-for-therapeutic-delivery-applications(76cee616-80bf-4b31-89d1-63f699573e78).html.
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The effect of peptide charge on the self-assembly and gelation behaviour of three octa-peptides: VEVKVEVK (VEK2), VKVKVEVK (VEK3) and VEVEVKVE (VEK1) has been investigated and characterised. The critical gelation concentration of each peptide was found to correlate with the charge modulus carried by the peptide and to be independent of the sign of the charge. Hydrogels formed were found to be transparent and stable when the peptide charge modulus is > 1. No differences in hydrogel structure or mechanical properties, as probed by TEM and SAXS and shear rheology, were found when the peptides were at the same concentration and carried the same charge modulus. These peptides were shown to form dense fibrillar network formed by β-sheet rich single fibre which lateral aggregation is controlled by the peptide charge modulus. The increase in fibre lateral aggregation with decreasing charge modulus was found to correlate with the increase in hydrogel mechanical properties, showing that fibre lateral aggregation pays a key role in controlling the mechanical properties of these hydrogels. The release profiles from VEK1 and VEK3 at pH 7 of two hydrophilic model drug molecules, namely napthol yellow (NY) and martius yellow (MY) was analysed using UV-Vis spectrophotometry. The incorporation of the guest molecules did not affect the self-assembly of the peptide at a molecular level but did affect the level of lateral fibre aggregation observed and therefore the mechanical properties of the hydrogels. The release of each of the model compounds was monitored over time and shown to be controlled by Fickian diffusion. The guest molecule diffusion rate D was dependent on the ratio between the overall effective charges carried by the peptide, i.e.: the fibrillar network, and the overall charges carried by the guest molecules but independent from the hydrogel concentration and mechanical properties, in the concentration and guest loading range investigated. This work shows that the rate of release of small drug molecules can be manipulated, not only by changing the charges on the guest molecules, but also by manipulating the charged state of the self-assembling peptide molecule and through it the charge state of the fribrillar network. Furthermore the VEK3 system was conjugated to a series of thermo-responsive synthetic polymers which imparted a significant change in mechanical properties, assembled structures and release profiles upon heating. Observed changes when above the polymers LCST include increased mechanical strength, fibre thickening and increased diffusion coeffcients. The synthesis, and subsequent characterisation, of these materials is the first time responsive hydrogels of OEGMA copolymers has been reported.
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Kilian, Gareth. "Development and testing of liposome encapsulated cyclic dipeptides." Thesis, Nelson Mandela Metropolitan University, 2011. http://hdl.handle.net/10948/1397.
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Cyclic dipeptides have been well characterized for their multitude of biological activities, including antimicrobial and anticancer activities. Cyclo(His-Gly) and cyclo(His-Ala) have also recently been shown to possess significant anticancer activity against a range of cell lines, despite the limitations of these two molecules with respect to their physicochemical properties. Low Log P results in poor cell permeability which can often be problematic for drugs with intracellular mechanisms of action. It can also results in poor biodistribution, and theoretical Log P values for cyclo(His-Gly) and cyclo(His-Ala) were extremely low making them ideal candidates for inclusion into a nanoparticulate drug delivery system. The aim of this study was therefore to formulate and evaluate liposome-encapsulated cyclic dipeptides that increase the tumour-suppressive actions of the cyclic dipeptides, while showing a high degree of specificity for tumour cells. While liposomes are relatively simple to prepare, inter batch variation, low encapsulation and poor stability are often problematic in their production and this has lead to very few liposomal products on the market. This study aimed at using a comprehensive statistical methodology in optimizing liposome formulations encapsulating cyclo(His-Gly) and cyclo(His-Ala). Initial screening of potential factors was conducted using a 25-1 fractional factorial design. This design made use of two levels for each of the five factors and abbreviated the design to minimize runs. Although not much information is provided by these types of designs, the design was sufficient in identifying two critical factors that would be studies further in a more robust design. The two factors selected, based on the screening study, were cholesterol and stearylamine content. These two factors were then used in designing a response surface methodology (RSM) design making use of a central composite rotatable vii design (CCRD) at five levels (-1.5, -1, 0, 1, 1.5) for each factor in order to better understand the design space. Various factors influenced the measured responses of encapsulation efficiency, zeta potential, polydispersity index, cellular uptake and leakage, but most notable were the adverse effects of increasing stearylamine levels on encapsulations efficiency and cholesterol levels on leakage for both cyclo(His-Gly) and cyclo(His-Ala) liposomes. Optimized formulations were derived from the data and prepared. Fair correlation between the predicted and measured responses was obtained. The cytotoxic activity of the encapsulated cyclic dipeptides were assessed against HeLa and MCF-7 cells and found to have limited improvement in activity. However, modification of the polyethylene glycol (PEG) grafted to the liposome surface in order to target folate receptors showed good benefit in significantly decreasing the IC50 values recorded in all cells lines tested, particularly low folate HeLa cells with the lowest IC50 being recorded as 0.0962 mM for folate targeted cyclo(His-Ala). The results therefore indicate that hydrophilic cyclic dipeptides are ideal candidates for inclusion into targeted drug delivery systems such as liposomes. Key words: Liposomes, cyclo(His-Gly), cyclo(His-Ala), cyclic dipeptides, HeLa, MCF-7, folate receptors, factorial design, response surface methodology (RSM), central composite rotatable design (CCRD).
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Ngwa, Conelius. "Use of peptide nucleic acids as therapeutic agents." Thesis, Aston University, 2014. http://publications.aston.ac.uk/24385/.
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Qian, Yun. "Self-assembled Peptide Hydrogels for Therapeutic H2S Delivery." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/101094.
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Hydrogen sulfide (H2S) is a gasotransmitter that is produced endogenously and freely permeates cell membranes. It plays important roles in many physiological pathways, and by regulating these pathways, it provides many therapeutic effects. For example, H2S dilates vascular vessels, promotes angiogenesis, and protects cells from oxidative stress. Due to its therapeutic effects, H2S has been used as a potential treatment for diseases like diabetes, ischemia-reperfusion injuries, lung diseases, ulcers and edemas, among others. To apply H2S for therapeutic applications, two challenges need to be addressed. The first challenge is the H2S donor, which not only provides H2S but must be stable enough to avoid side effects caused by overdose; and the second challenge is the delivery strategies, which transport the H2S to the target sites.
A series of S-aroylthiooximes (SATOs), an H2S releasing compound, were synthesized and conjugated to peptide sequences to form H2S-releasing aromatic peptide amphiphile (APA) hydrogels. APAs formed nanofibers, which were stabilized by beta-sheets and aromatic stacking. The self-assembled structures were affected by the substituents on the aromatic rings of SATOs, leading to the formation of twisted nanofibers. After the addition of cysteine, H2S was released from the APAs with half-lives ranging from 13 min to 31 min. The electron-donating groups slowed down the H2S release rate, while the electron-withdrawing groups accelerated the release rate. Therefore, the release rates of H2S were controlled by electronic effects. When self-assembled structures were formed, the H2S release rate was slowed down even more, due to the difficulties in cysteine diffusion into the core of the structures.
Antimicrobial effects were also discovered using the H2S releasing APA hydrogels. The H2S-releasing dipeptides S-FE and S-YE formed self-assembled twisted nanoribbons and nanotubes, respectively. The non H2S-releasing control oxime dipeptides C-FE and C-YE were also synthesized. The C-FE formed nanoribbons while the C-YE only showed non-specific aggregates. S-FE and S-YE released H2S with peaking times of about 41 and 39 min. Both the self-assembled structures and the release rates were affected by their packing differences. In vitro and ex vivo experiments with Staphylococcus aureus (Xen29), a commonly found bacterium on burn wounds, showed significant antimicrobial effects. APAs S-FE and C-FE eliminated Xen29 and inhibited the biofilm formation, while S-FE always showed better effects than C-FE. These antimicrobial H2S-releasing APA hydrogels provide a new approach to treat burn wound infections, and provide healing benefits due to the therapeutic effects of H2S.Doctor of Philosophy
6
Parker, Alan. "Development of peptide-targeted gene delivery systems." Thesis, University of Birmingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273727.
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Tasdemiroglu, Yagmur. "Small Therapeutic Peptides: In vitro pharmacokinetics of alpha-carboxyl terminus 11 peptide in rat plasma." Thesis, Virginia Tech, 2021. http://hdl.handle.net/10919/103639.
Full textAbstract:
Cardiovascular diseases affect one third of the U.S. population and are the number one cause of death globally. Acute myocardial infarction is one of the most catastrophic cardiovascular diseases that permanently alters patient's lives. Small molecule drugs, surgery, medical devices and lifestyle changes are the current treatment methods that only address symptoms and fail to cure cardiovascular disorders. Small therapeutic peptides are emerging methods to treat diseases ranging from cancer to auto-immune disorders. Due to their nature, they are non-toxic, non-immunogenic, biocompatible and highly target specific. However, because of their small size and lack of tertiary structure, they have a very short half-life.
Alpha-carboxyl terminus 11 peptide (αCT11) is a 9 amino acid long small peptide that has shown to promote left ventricular function recovery when mouse hearts are perfused with the peptide prior to an ischemia-reperfusion injury. This study investigates the in vitro pharmacokinetics of αCT11 in rat plasma in the presence of protease and phosphatase inhibitor cocktails to provide a method to delay its degradation and to understand the degradation pattern of the peptide in vitro. The effect of time, temperature, presence of inhibitors and sex are investigated. Results have shown that while sex does not have a significant effect on αCT11 degradation, time and temperature significantly promote its degradation. Utilization of inhibitors also leads to a pronounced delay in αCT11 degradation, as the amount of αCT11 remaining in plasma increases from almost undetectable to 15-16% upon introduction of inhibitors. These results indicate that αCT11 degradation can be delayed significantly when inhibitor cocktails are used, bringing αCT11 closer to being used in a clinical setting to address ischemia-reperfusion injuries.Master of Science
Cardiovascular diseases affect millions of people worldwide and they are the number one cause of death globally. Current treatments for cardiovascular diseases mainly focus on alleviating symptoms as they arise and delaying the disease progression using small molecule drugs and lifestyle changes, which unfortunately are unable to cure the diseases permanently. Peptide treatment is a novel method to address various traditionally incurable diseases, such as auto-immune disorders and cancer. These therapeutic peptides are highly target specific, typically non-toxic and highly biocompatible since they are designed based on native proteins. Even though small therapeutic peptides have numerous benefits, a major drawback is that they have a very short half-life in plasma. Alpha-carboxyl terminus 11 peptide (αCT11) is a small peptide derived from alpha-carboxyl terminus 1 peptide (αCT1), which is in phase 2 clinical trials for chronic wound healing. It has been shown that αCT11 has cardioprotective effects when the heart is perfused with the peptide before an ischemia-reperfusion injury, such as a heart attack. This study investigates the in vitro pharmacokinetic properties of αCT11 in rat plasma with respect to time, temperature and sex with the aim to provide an effective method to allow αCT11 to remain in plasma for a longer period of time. As a method to delay αCT11 degradation due to plasma enzymes, enzyme inhibitors are used, which delayed the αCT11 breakdown significantly. The results have also shown that time and temperature are the main factors affecting αCT11 degradation in rat plasma in vitro while sex is not a significant factor. These results indicate that this small peptide can be protected in plasma with the use of inhibitors. This discovery can be a stepping stone to use αCT11 in clinical settings to help treat cardiovascular diseases.
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Barrios, Marrugo Kelly. "Therapeutic Peptide-Based Vaccination Strategies Against HPV-Induced Cancers." Scholar Commons, 2012. http://scholarcommons.usf.edu/etd/4283.
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There is an urgent need for the development of an effective therapeutic vaccine against cancer caused by human papilloma virus (HPV). We focused on HPV-induced malignancies because of their high worldwide prevalence (e.g., cervical carcinoma and head & neck cancer). A successful therapeutic vaccine could prevent the 250 000 deaths/year worldwide and the 2.25 billion dollars that
are expended in related care in the US.
We used an HPV-induced mouse cancer model to test vaccines
composed of a CD8 T cell peptide epitope administered with potent adjuvants designed to generate vast numbers of high avidity cytotoxic T lymphocytes specific for the HPV16-E7 antigen. One vaccination strategy (TriVax) consists of intravenous administration of synthetic peptide HPV16-E749-57 administered together with a Poly-IC (a TLR3 agonist) and anti-CD40 monoclonal antibody(αCD40 mAb) while the second more simple strategy (BiVax) comprises solely of peptide plus Poly-IC. We used an E7 peptide as antigen in the vaccination strategies because expression of the viral E6 and E7 proteins is required to maintain oncogenic phenotype and because normal cells do not express E6/E7, therefore a therapeutic vaccine targeting these proteins has several advantages:
a) a strong immune response can be induced since immune tolerance to these foreign antigens does not exist and b) the strong immune response should not inflict damage to normal cells.
TriVax and BiVax generate a high number of antigen specific CD8 T cells capable clear subcutaneous tumors and prevent recurrences, both vaccines are efficient through the i.v. and i.m. route. TriVax (prime-boost) clears tumor in 100% of mice while BiVax clears tumor in 50% of mice, this differential effect is due to the number of antigen specific CD8 T cells and increasing the number of booster shot makes BiVax as immunogenic and efficient in clearing tumors. In the absence of type-I IFN signaling (in IFNαΒR KO mice), TriVax is less effective in generating sufficient numbers of CD8 T cells that could be necessary for total disease eradication. We observed a significant anti-tumor effect of TriVax in the absence of interferon gamma, however the cytokine may play some role in the overall effectiveness of TriVax to completely reject the tumors. Immune responses produced by BiVax are highly dependent on the simultaneous administration of peptide and Poly-IC, on the peptide composition, vaccine formulation and route of administration. The magnitude of the response is dependent on the expression of the Poly-IC receptors TLR3 and melanoma differentiation-associated protein 5 (MDA5). Interestingly, the magnitude and duration of the CD8 T cell responses generated by peptide and Poly-IC mixtures does not rely on the presence of CD4 T cells, scavenger receptor-A (SR-A) or type-I IFN signals and was minimally affected by the absence of CD40 signaling.
The present findings could facilitate the development of simple and effective subunit vaccines for diseases where CD8 T cells may hold a therapeutic benefit.
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Kwok, Hoi-shan, and 郭凱珊. "The comparison of biological properties of L- and D-enantiomeric antimicrobial peptides." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2014. http://hdl.handle.net/10722/206507.
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Antibiotics have been used widely for the treatment of bacterial infections for over half a century. However, the emergence of resistance to antibiotics has aroused public health concern, leading to the development of antimicrobial peptides (AMPs) as potential alternative therapeutic agents against bacterial infections. AMPs are naturally found in many species and have important roles in our innate immune defense systems. AMPs are usually cationic amphipathic peptides with membrane destabilizing property. They have a relatively broad spectrum of antimicrobial activity and pathogens are less likely to develop resistance against AMPs. The major challenge of using AMPs as therapeutic agents is their toxicity towards mammalian cells. The biological stability of AMPs to protease in human body is another concern.
To address the latter problem, instead of the naturally occur L-enantiomers, Denantiomeric AMPs were introduced to enhance their stability. This study aimed to test the hypothesis that the D-enantiomeric AMPs are more resistant than the Lenantiomeric AMPs against proteolytic degradation. Three pairs of synthetic D-/LAMPs (D-LAO160-P13/LAO160-P12; D-LAO160-H/LAO160-H; and D-LAK-120-HP13/LAK-120-HP13) were employed to test for their stability when treated with trypsin, serum and gastric fluid, and the samples were analyzed by high performance liquid chromatography (HPLC). Generally, all the D-enantiomeric AMPs were found to be resistant towards proteolysis. Besides, to compare the cytotoxicity of D-/LAMPs, MTT and LDH assays of the D/L-LAK120-HP13 pair were carried out on two different cell lines, A549 cells (human lung adenocarcinoma epithelial cells) and RAW264.7 cells (mouse macrophage cells). Significant difference in cytotoxicity of D-LAK120-HP13 and LAK120-HP13 on RAW264.7 cells were obtained from MTT assay, but not in LDH assays or on A549 cells. Further analysis has to be done to validate the findings obtained from this research.published_or_final_version
Pharmacology and Pharmacy
Master
Master of Medical Sciences
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Makhani, Kiran, and Kiran Makhani. "Mechanism of Action of ERBB Decoy Cancer Therapeutic Peptide SAH5." Thesis, The University of Arizona, 2017. http://hdl.handle.net/10150/626139.
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Breast cancer is the most prevalent type of cancer and second leading cause of death in women. Among others, the triple negative breast cancer (TNBC) is the most invasive as it has the highest recurrence and death rates with no targeted therapeutic available thus far. Epidermal Growth Factor Receptor (EGFR) is one of the important targets as more than fifty percent of the TNBC overexpress it but all the therapies designed against it have failed to show significant results. The juxtamembrane domain of EGFR has been explored comparatively recently and has been used to design a decoy peptide with the anticipation to affect the EGFR downstream functions. Previous research has shown it to cause cell death in cancer cells. This study is aimed towards deciphering the mechanism of action of the stapled form of this decoy peptide-SAH5. It presents evidence that the peptide leads to an immediate intracellular calcium release from the Inositol 1,4,5 triphosphate on the endoplasmic reticulum, an inhibition of which can rescue SAH5 induced cell death. The study also demonstrate that the peptide is able to increase the production of Reactive Oxygen Species (ROS) in mitochondria, part of which is triggered by the peptide-induced calcium release.
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Park, Kwijun. "Therapeutic potential of atrial natriuretic peptide administration on peripheral arterial diseases." Kyoto University, 2008. http://hdl.handle.net/2433/135849.
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Kritzinger, André Louis. "The medicinal chemistry of cyclo (Ser-Ser) and cyclo (Ser-Tyr)." Thesis, Nelson Mandela Metropolitan University, 2007. http://hdl.handle.net/10948/537.
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Cyclic dipeptides are widely used as models for larger peptides because of their simplicity and limited conformational freedom. Some cyclic dipeptides have been shown to produce antiviral, antibiotic and anti-tumour activity (Milne et al., 1998). In this study the cyclic dipeptides, cyclo(Ser-Ser) and cyclo(Ser-Tyr), were synthesised from their corresponding linear precursors using a modified phenolinduced cyclisation procedure. The phenol-induced cyclisation procedure resulted in good yields and purity of the cyclic dipeptides. Quantitative analysis and evaluation of the physicochemical properties of the cyclic dipeptides was achieved by using high-performance liquid chromatography, scanning electron microscopy, thermal analysis and X-ray powder diffraction. The structures of the synthesised cyclic dipeptides were elucidated using infrared spectroscopy, mass spectrometry, nuclear magnetic resonance spectroscopy and molecular modelling. The study aimed to determine the biological activity of cyclo(Ser-Ser) and cyclo(Ser-Tyr) with respect to their anticancer, antimicrobial, haematological and cardiac effects. Anticancer studies revealed that cyclo(Ser-Ser) and cyclo(Ser- Tyr) inhibited the growth of HeLa (cervical cancer), HT-29 (colon cancer) and MCF (breast cancer) cancer cell lines. Both cyclic dipeptides also inhibited the growth of certain selected Gram-positive, Gram-negative and fungal microorganisms in the antimicrobial study. Although the inhibition of growth in the anticancer and antimicrobial studies was statistically significant, the clinical relevance is questionable, since the inhibition produced by both cyclic dipeptides was very limited compared to other pre-existing anticancer and antimicrobial agents. Cyclo(Ser-Tyr) exhibited significant activity in the haematological studies, where it increased the rate of calcium induced-coagulation, and decreased the rate of streptokinase-induced fibrinolysis. Both cyclic dipeptides, however, failed to produce any significant effects on thrombin-substrate binding and ADPinduced platelet aggregation. Cardiac studies revealed that cyclo(Ser-Ser) and especially cyclo(Ser-Tyr) reduced the heart rate, coronary flow rate and ventricular pressure of isolated rat hearts.
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Riaz, Muhammad Kashif. "Peptide functionalized drug delivery system for an efficient lung cancer therapy." HKBU Institutional Repository, 2019. https://repository.hkbu.edu.hk/etd_oa/609.
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Lung cancer has a high incidence rate globally and the leading cause of cancer related mortalities. In 2018, lung cancer has been estimated to cause 1.76 million deaths worldwide (18.33% of total cancer mortalities). In Hong Kong lung cancer has been a leading cause of cancer related deaths, and in 2016 caused 3780 deaths (26.6% of total cancer mortalities). Non-small cell lung cancer (NSCLC) is the major (~85%) lung cancer type, and five-year survival rate for lung cancer has estimated to be 18%. Thus, an efficient lung cancer treatment with lesser adverse effects is need of the hour. In this connection, active targeting of overexpressed receptors at lung tumor site with a ligand functionalized drug delivery system is the current approach, and pulmonary administration could augment chemotherapeutic effect of the drug through localized administration, minimizing the off-target effects by retention of the drug in lungs.Quercetin (QR), a natural flavonoid present in edible fruits and vegetables possess anticancer activity i.e. inhibits lung cancer growth. However, the application of QR in lung cancer therapy has been restricted by various factors i.e. low water solubility (2.15 µg/ml at room temperature), low bioavailability and rapid plasma clearance. To overcome the issues, we have formulated various QR-loaded liposomes surface functionalized with transferrin receptor (TFR) targeting peptides i.e. T7 (HAIYPRH) and T12 (THRPPMWSPVWP) in two research projects with active targeting ability, prolonged circulation time, and sustained release behavior for lung cancer specific QR delivery. In first research project, T7 targeted liposomes with different peptide densities i.e. 0.5%, 1% and 2% and QR-lip (non-targeted) were formulated. TFRs are over expressed (~100 folds) in various cancers including lung cancer and have low expression in most normal cells. T7 surface-functionalized liposomes (2% T7-QR-lip) demonstrated significantly enhanced cytotoxicity (~3-folds), cellular-uptake, S-phase cell cycle arrest and apoptosis in A549 cells. However, in MRC-5 (normal-lung fibroblast) cells no significant difference was observed after treatment with T7-QR-lip and QR-lip in cytotoxicity and cellular uptake studies. In tumor spheroid penetration and inhibition studies, T7 targeted liposomes showed deeper penetration and pronounced inhibition. In vivo biodistribution study via pulmonary administration of T7-DiR-lip has demonstrated liposomes accumulation in the lungs and sustained-release behavior upto 96h. Further, T7-QR-lip significantly enhanced anticancer activity of QR and life-span of orthotopic lung-tumor bearing mice (**p < 0.01, compared with control) via pulmonary administration. In second research project, T12 surface-functionalized liposomes with 0.5%, 1% and 2% T12 peptide densities and QR-lip have been formulated with ~95 % encapsulation efficiency. In vitro drug release study showed sustained release of QR from T12-QR-lip and QR-lip. In vitro experiments showed A549 cells treatment with 2% T12-QR-lip enhanced cellular-uptake, in vitro cytotoxicity, induced apoptosis and S-phase cell cycle arrest due to TFR mediated endocytosis. No significant variation has been observed in cellular-uptake and cytotoxicity after MRC-5 cells were treated with T12-QR-lip and QR-lip. Further, T12-Cou6-lip showed significantly deeper penetration i.e. 120 µm in 3D lung tumor-spheroids. Biodistribution study showed retention of T12-DiR-lip and DiR-lip mainly in the lungs upto 96h after pulmonary administration, as compared to free DiR. Pulmonary administration of T12-QR-lip showed the strongest tumor growth inhibition and survival time of orthotopic lung tumor implanted mice without any systemic toxicity as compared to QR-lip and free-QR. In summary, in vitro and in vivo results of the two research projects suggest that surface functionalization of the liposomes with TFR targeting peptides i.e. T7 and T12 is a promising approach for lung cancer therapy through active targeting and receptor mediated endocytosis of QR at lung tumor site. Moreover, T7 and T12 functionalized liposomes provides a potential drug delivery system for a range of anticancer drugs to enhance their therapeutic efficacy by localized i.e. pulmonary administration and targeted delivery.
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Su, Hsin-Yuan. "Therapeutic Potential of EGFR Derived Peptides in Breast Cancer." Diss., The University of Arizona, 2013. http://hdl.handle.net/10150/293486.
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The epidermal growth factor receptor (EGFR) belongs to the erbB family of receptor tyrosine kinases which consists of four members (EGFR, ErbB2, ErbB3 and ErbB4). Upon ligand binding, the EGFR is capable of dimerization with other erbB receptors and propagates signals regulating a diverse array of cellular physiologies, including cell growth, migration and survival. Dysregulation of the EGFR is important for development and progression of different types of cancers, including breast cancer. Breast cancer is the second leading cause of cancer death in women. EGFR overexpression has been observed in about 15% of all breast cancers. Moreover, in triple negative breast cancer (TNBC), which is a more aggressive type of breast cancer and lacks effective therapies, up to 50% of tumors are found to overexpress EGFR. Targeted therapy against EGFR has been used in TNBC. However, limited efficacy has been observed in TNBC due to intrinsic and acquired resistant mechanisms. In order to overcome this issue, we have developed two novel therapeutic peptides derived from the nuclear localization signal (NLS) sequence and juxtamembrane domain of EGFR and investigated their efficacy in regard to inhibiting EGFR translocation and activation in TNBC. EGFR has been found to translocate into the nucleus and nuclear EGFR can affect gene transcription, cell proliferation, stress response and DNA repair through interacting with different components in the nucleus. Importantly, these functions of nuclear EGFR correlate with cancer prognosis and therapeutic resistance. We found that an EGFR NLS-derived peptide (ENLS peptide) could inhibit activated EGFR (pY845) undergoing nuclear translocation. We also showed that this ENLS peptide sensitized breast cancer cells to AG1478 (EGFR tyrosine kinase inhibitor) treatment. The juxtamembrane domain of EGFR regulates its trafficking to the nucleus and mitochondria, interaction with calmodulin and calcium signaling, and participates in dimerization and activation of EGFR. These non-traditional kinase related functions of EGFR represent a novel target for EGFR therapy. We found that a mimetic peptide of the juxtamembrane domain of EGFR (EJ1 peptide) could effectively inhibit EGFR activation through promoting inactive dimer formation. It could also effectively kill cancer cells through processes of apoptosis and necrosis. Mechanistically, this EJ1 peptide affects membrane integrity thereby leading to calcium influx, disruption of mitochondrial membrane potential and reactive oxygen species (ROS) accumulation. Importantly, EJ1 peptide appeared to be effective in inhibition of tumor growth and metastasis in a transgenic mouse model of breast cancer and showed no observable toxicity. ErbB3, another member of the erbB family, represents an important driver of the parallel signaling pathway to EGFR as well as a key regulator of PI3K/AKT activity which is important for therapeutic resistance. ErbB3 has been shown to interact with MUC1. The interaction between MUC1 and EGFR promotes EGFR stability through recycling of receptors. We found that MUC1 expression also affected ErbB3 activity and stability through ErbB3/EGFR/MUC1 complex formation. In conclusion, we demonstrated that two EGFR-derived peptides, working through novel strategies, represent a new foundation of effective therapeutic agents to breast cancer. ErbB3/EGFR/MUC1 complex formation under MUC1 expression also represents a druggable target for ErbB3 activity and stability.
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Konkel, Joanne Elizabeth. "Signals required for the induction of antigen-based therapeutic tolerance." Thesis, University of Edinburgh, 2009. http://hdl.handle.net/1842/3942.
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Despite the actions of central tolerance during thymic selection, it is clear that the peripheral T cell repertoire contains significant numbers of self-reactive T cells. The immune system needs to curtail the risk of autoimmune disease by controlling the activity of these self-reactive T cells. Various mechanisms are in place to achieve this control (peripheral tolerance). Activation of CD4+ T cells requires two signals; engagement of the T cell receptor (TCR) with an appropriate peptide:MHC complex (signal 1), and the aggregate effect of multiple signals generated following ligation of costimulatory and coinhibitory molecules (signal 2). Both signals are required for the generation of a productive T cell response and both are provided by the professional antigen presenting cell, the dendritic cell (DC). T cells are fully activated upon receiving both signal 1 and 2, but are rendered tolerant when they receive only signal 1. This can be exploited therapeutically through the administration of peptides to induce tolerance in peptidereactive T cells. Administration of peptide with an adjuvant provides both signal 1 and 2, and leads to a sustained T cell response against the administered peptide (immunity). However, if the same peptide is administered in soluble form, only signal 1 is provided, leading to the establishment of T cell tolerance. The studies in this thesis explore the role of both signal 1 and signal 2 in peptide-induced T cell tolerance. Previous data from our laboratory have highlighted PD-1 and RANKL as costimulatory molecules which could play a role in peptide-induced T cell tolerance. Here we show that PD-1, an important coinhibitory molecule, plays a vital role in restraining peripheral T cell expansion under conditions leading to T cell immunity. However, in contrast to data from other studies, we demonstrate that PD-1 plays no role in the induction, establishment or maintenance of peptide-induced T cell tolerance. We show that the costimulatory receptor ligand pair RANK:RANKL plays a role in the balance between T cell tolerance and immunity; as administration of anti-RANKL was seen to potentiate both tolerance and immunity. We also explored the effect of altering the affinity of a peptide for MHC on the induction of peptide tolerance. We demonstrate that use of a peptide with a high-affinity for MHC induces tolerance via a novel, non-deletional mechanism of peptide-tolerance induction. Importantly, we show that the high-affinity peptide can form peptide- MHC complexes which persist in a biologically relevant form for fourteen days following peptide administration. We suggest that this leads to chronic stimulation of peptide-reactive T cells which promotes acquisition of a novel tolerant phenotype. Collectively the work described in this thesis demonstrates the important roles both signal 1 and 2 play in therapeutic-tolerance induction and how the qualitative and quantitative alteration of these signals can alter T cell fate and/or responsiveness.
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Lin, Kim-fung. "Evaluation of calcium/calmodulin kinase II as therapeutic target in beta-amyloid peptide neurotoxicity." Thesis, Click to view the E-thesis via HKUTO, 2004. http://sunzi.lib.hku.hk/hkuto/record/B3145253X.
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Aldughaim, Mohammed. "The use of a novel TIMP3 peptide to specifically target therapeutic drugs to tumours." Thesis, University of Sheffield, 2017. http://etheses.whiterose.ac.uk/19957/.
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Zhu, Maximillian. "Computational studies of the Alzheimer's amyloid-β peptide : from structural ensembles to therapeutic leads." Thesis, University of Cambridge, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.608056.
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Yuan, Tifei, and 袁逖飞. "Self-assembling peptide nanofiber scaffold treatment to acutely injured olfactory bulb." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B43816277.
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Grönwall, Caroline. "Affibody molecules for proteomic and therapeutic applications." Doctoral thesis, KTH, Molekylär Bioteknologi, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4674.
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This thesis describes generation and characterization of Affibody molecules with future applications in proteomics research, protein structure determinations, therapeutic treatment of disease and medical imaging for in vivo diagnostics. Affibody molecules are engineered affinity proteins developed by combinatorial protein engineering from the 58-residue protein A-derived Z domain scaffold. Novel Affibody molecules targeting human proteins were selected from a combinatorial library using phage display technology. In the first two investigations, an Affibody molecule specifically targeting the high abundant human serum protein transferrin was generated. The intended future use of this Affibody ligand would be as capture ligand for depletion of transferrin from human samples in proteomics analysis. Strong and highly specific transferrin binding of the selected Affibody molecule was demonstrated by biosensor technology, dot blot analysis and affinity chromatography. Efficient Affibody-mediated depletion of transferrin in human plasma and cerebrospinal fluid (CSF) was demonstrated in combination with IgG and HSA removal. Furthermore, depletion of five high abundant proteins including transferrin from human CSF gave enhanced identification of proteins in a shotgun proteomics analysis. Two studies involved the selection and characterization of Affibody molecules recognizing Alzheimer’s amyloid beta (Abeta) peptides. Future prospect for the affinity ligands would primarily be for therapeutic applications in treatment of Alzheimer’s disease. The developed A-binding Affibody molecules were found to specifically bind to non-aggregated forms of Abeta and to be capable of efficiently and selectively capture Abeta peptides from spiked human serum. Interestingly, the Abeta-binding Affibody ligands were found to bind much better to Abeta as dimeric constructs, and with impressive affinity as cysteine-bridged dimers (KD~17 nM). NMR spectroscopy studies revealed that the original helix one, of the two Affibody molecules moieties of the cysteine-bridged dimers, was unfolded upon binding, forming intermolecular β-sheets that stabilized the Abeta peptide, enabling a high resolution structure of the peptide. Furthermore, the Abeta-binding Affibody molecules were found to inhibit Abeta fibrillation in vitro. In the last study, Affibody molecules directed to the interleukin 2 (IL-2) receptor alpha (CD25) were generated. CD25-binding Affibody molecules could potentially have a future use in medical imaging of inflammation, and possibly in therapeutic treatment of disease conditions with CD25 overexpression. The selected Affibody molecules were demonstrated to bind specifically to human CD25 with an apparent affinity of 130-240 nM. Moreover, the CD25-targeting Affibody molecules were found to have overlapping binding sites with the natural ligand IL-2 and an IL-2 blocking monoclonal antibody. Furthermore, the Affibody molecules demonstrated selective binding to CD25 expressing cells.QC 20100729
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þráinsdóttir, Inga S. "Glucose abnormalities and heart failure : epidemiological and therapeutic aspects /." Stockholm, 2005. http://diss.kib.ki.se/2005/91-7140-389-2/.
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Askar, Basim Ali. "The therapeutic potential of vasoactive intestinal peptide (VIP) in the treatment of Gram-negative sepsis." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/32887/.
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Gram-negative bacteria are the most common cause of the sepsis and lipopolysaccharide (LPS) a major component of Gram-negative bacteria is known to be of major importance in the development of sepsis. Human infection with Salmonella, a Gram-negative bacterium, is associated with a number of cases of sepsis and is particularly important in childhood sepsis. During salmonellosis, monocytes and macrophages produce a number of different pro-inflammatory mediators such as TNF-α, IL-1α, IL-12, IL-18, IFN-γ, reactive nitrogen species and oxygen species. Although the production of these inflammatory mediators is required for resolution of bacterial infections, they are contraindicated in diseases such as sepsis. In the initial (acute) phase of sepsis a Systemic Inflammatory Response Syndrome (SIRS) occurs in which inflammatory mediators are produced in high concentration, which can lead to organ failure and death. The SIRS phase is then replaced by a Compensatory Anti-inflammatory Response Syndrome (CARS) phase which leads to immunosuppression. The CARS phase can lead to secondary infection and subsequent mortality within 28 days of hospital admission. To date, several studies have evaluated the role of vasoactive intestinal peptide (VIP) as an anti-inflammatory agent that may have therapeutic potential in septic patients both in vitro and in vivo. VIP has been shown to inhibit production of inflammatory mediators produced by human monocytes in response to LPS. The aim of the work described in this thesis was to investigate the therapeutic potential of VIP in sepsis using an ex vivo human monocytes model infected with viable Salmonella Typhimurium 4/74 (rather than LPS). The study shows that VIP (10-7 M) stimulates an increase in the numbers of Salmonella recovered from infected human monocytes (MOI = 10). In addition, VIP also increases the survival rate of human monocytes infected with Salmonella. These two results may suggest a detrimental effect of VIP during bacteraemia and sepsis, since monocyte death may be beneficial during sepsis and bacterial overgrowth could lead to further increased LPS (and other antigen) stimulation of the immune system. However, VIP did significantly decrease Salmonella and LPS-induced TNF-α, IL-1β and IL-6 in monocyte supernatants. VIP also had a positive effect on IL-10 production in human monocytes infected with Salmonella or stimulated with LPS. Whether this suggests a possible detrimental effect of VIP is unknown but septic patients with high serum IL-10/ low TNF-α concentration ratio have previously been shown to have a poor prognosis. Higher IL-10 concentrations in infected monocytes (due to VIP) could also increase the CARS phase of disease with increased immunosuppression. Flow cytometry and qPCR analyses showed that of all of the VIP receptors, VPAC1 was expressed most highly during Salmonella infection, or LPS stimulation, of human monocytes. Administration of VIP inhibited VPAC1 has been shown by many studies to be the most important receptor by which VIP inhibits production of inflammatory immune mediators, or increases IL-10 production from murine macrophages. Results in this thesis, therefore, suggested that Salmonella infection may promote VPAC1 expression and so provide a mechanism of inhibiting the production of inflammatory mediators in infected cells. This could then increase intracellular survival of Salmonella and provide a means of greater dissemination of the infection. To ascertain how increased VPAC1 expression on the surface of monocytes may be achieved, analysis of the expression of known intracellular endosomal and exosomal constituents was performed. Confocal laser microscopy, using specific antibodies, showed that VPAC1 on the monocyte cell membrane was internalised within early endosomes (measured by co-localisation of VPAC1 and EEA1) rather than being degraded within lysosomes (measured by immunoreactivity to LAMP1). VPAC1 is then transported via a Rab11A recycling endosome and packaged in the Trans-Golgi network (TGN), shown by co-localisation of VPAC1/Rab11A and the TGN marker (TGN46). VPAC1 was then associated with Rab3a and calmodulin. The function of these latter two proteins in the docking of exosomes to the cell membrane is well known, thus suggesting that Salmonella induced VPAC1 was also recycled to the cell membrane within exosomes. VIP inhibited the expression of both Rab3a and calmodulin but not the co-localisation of VPAC1 with these two proteins. Further studies then showed that a calmodulin agonist (CALP1) increased VPAC1 expression on the surface of monocytes, while a calmodulin antagonist (W-7) decreased expression of VPAC1 on the surface of monocytes. In conclusion, this thesis does present hitherto unknown data regarding Salmonella infection of human monocytes and the effects of VIP on infected monocytes. VIP has potential as an anti-sepsis therapy since it reduces the production of inflammatory mediators by Salmonella-infected and LPS-stimulated monocytes. However, the fact that VIP increases survival of infected human monocyte and increased growth of Salmonella in human monocytes may preclude its use in sepsis.
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Allen, Stephanie D. "Therapeutic peptidomimetic strategies for costimulation blockade in multiple sclerosis and transplantation / conformational peptide vaccines of the HER-2/neu dimerization loop are effective in inhibiting mammary tumor growth in vivo." Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1150479940.
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Tshanga, Siphokazi Sisanda. "Antibacterial activity of liposome encapsulated cyclo(TYR-PRO)." Thesis, Nelson Mandela Metropolitan University, 2011. http://hdl.handle.net/10948/1450.
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Cyclic dipeptides (CDPs) are amino acid-based compounds, some of which possess antibacterial activity. The encapsulation of certain drugs into liposomes has been found to improve their activity in terms of bioavailability and duration of action. Liposomes are small vesicles that are under investigation as drug carriers for the delivery of therapeutic agents. A number of liposome formulations are currently under clinical trial review, whilst some have already been approved for clinical use. The aim of this study was to optimize a liposomal cyclo(Tyr-Pro) formulation and to assess its antibacterial activity against various Gram-positive and Gram-negative bacteria. Response surface methodology (RSM) using the central composite design (CCD) model was used to optimize liposomal formulations of cyclo(Tyr-Pro) for each of the four bacteria, namely Bacillus cereus, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. Percent drug encapsulated and bacterial inhibition were investigated with respect to two independent variables, i.e. lipid composition and cholesterol content. Design Expert 8 was used for the purpose of finding the combination of independent variables that would yield an optimal formulation for each bacterium. The model selected by the software failed to adequately correlate the predicted models to the experimental data. The in vitro experiments showed that the antibacterial activity of liposome-encapsulated cyclo(Tyr-Pro) was superior to that of its free counterpart. Binding maximum or Bmax for the encapsulated compound at concentrations as low as 0.412 mg/ml, was significantly higher than that obtained for free cyclo(Tyr-Pro) which was tested at a concentration of 20 mg/ml. Furthermore, encapsulation of cyclo(Tyr-Pro) into a liposome formulation enhanced its potency. This was evident in the lower IC50 values for the liposomal compound when compared to free cyclo(Tyr-Pro).
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Gawri, Rahul. "Link-N Peptide: a potential therapeutic agent for biological repair of early degenerated human intervertebral discs." Thesis, McGill University, 2014. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=121429.
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Chronic low back pain is a disease affecting a big portion of the population with 70% having at least one episode of low back during their lives. Intervertebral disc (IVD) degeneration is the most common cause of low back pain. It is associated with degradation and loss of proteoglycans, mainly aggrecan. Currently main treatment modalities offered for treating IVD degeneration are surgical and mainly target end stage disc disease. Medical therapies are being developed to treat and retard IVD degeneration and growth factor therapy is one such upcoming modality. Link protein is a component of IVD matrix. Link-N is a 16 amino acid peptide, cleaved from the N terminal of Link protein. It is found in the matrix of degenerating IVDs and is thought to have an effect on IVD metabolism including stimulation of proteoglycan synthesis. To test the regenerative potential of Link-N in degenerating human discs, IVD cells were exposed to the peptide. Link-N exposure resulted in a dose dependent increase in proteoglycan synthesis, stimulated proteoglycan synthesis and modulated protease production in an inflammatory environment. Organ culture models are commonly used tools for understanding disease process and action of potential therapeutic agents. There was no ideal model for studying IVD pathophysiology in humans; therefore a whole organ culture model was developed. This model maintained cell viability up to 4 months and Link-N peptide was able to stimulate sustained proteoglycan synthesis in the discs. In order to ensure a sustained effect of treatment, sustained activity is important. The stability of Link-N peptide was evaluated in the presence of IVD cells. Link-N was processed by IVD cells generating a new peptide retaining the bioactive properties of the parent peptide. Thus, the present study establishes Link-N peptide as a promising bioactive agent for treating IVD degeneration by regenerating degenerated discs and by retarding the ongoing degenerative process.La lombalgie est une maladie chronique affectant 70% de la population de plus de 60 ans. La dégénération des disques intervertébraux (DIVs) est la principale cause de lombalgie. Elle est associée à la degradation et la perte de protéoglycans, principalement de l'aggrécane. Les traitements présentement offerts, comme la chirurgie, visent les stades avancés de la maladie. Des facteurs de croissance ont aussi été utilisés pour traiter et/ou retarder la dégénération des DIVs. La protéine Link est une composante de la matrice des DIVs. Link-N est un peptide de 16 acides aminés produit par le clivage de la section N-terminale de la protéine Link. Link-N est retrouvé dans la matrice des disques en cours de dégénération et notre hypothèse est qu'il aurait un effet positif sur le métabolisme des DIVs. Afin de vérifier le potentiel régénérateur de Link-N, des cellules des DIVs ont été exposées au peptide. Nos résultats démontraient que Link-N induisait la synthèse de protéoglycans de façon dose-dépendante et modulait la production de protéases dans un environnement inflammatoire. Il n'existe pas de modèle idéal pour étudier la physiopathologie des DIVs humains. Nous avons donc développé un modèle de culture de DIVs entiers. La viabilité cellulaire a été maintenue jusqu'à 4 mois dans ce modèle. Aussi, Link-N fut capable de stimuler une synthèse soutenue de protéoglycans dans le disque, condition essentielle afin d'assurer un effet soutenu d'un traitement. Les études de la stabilité de Link-N dans les IVDs démontaient que le peptide était transformé et que le nouveau peptide généré par l'activité cellulaire conservait les propriétés bioactives du peptide parent. La présente étude établie donc le peptide Link-N comme un agent bioactif prometteur dans le traitement de la dégénération des DIVs et le ralentissement du processus dégénératif en cours.
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Sharma, Arpeeta. "Therapeutic use of a mutant Caveolin-1 peptide to reduce atherosclerosis induced by hypercholesterolemia and diabetes." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/51549.
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Endothelial dysfunction is a well-established response to cardiovascular risk factors, such as hypercholesterolemia and diabetes, and is the critical first step of atherogenesis. Nitric oxide (NO), the key regulator of endothelial function, is greatly diminished in atherosclerotic disease settings resulting in augmented oxidative stress and endothelial activation, a process that involves upregulation of endothelial adhesion molecules and increased leukocyte-endothelial interactions, all of which are major steps in the pathogenesis of atherosclerosis. Pharmacological inhibition of endothelial nitric oxide synthase (eNOS), the main vascular source of protective NO, induces endothelial dysfunction and promotes atherosclerosis. While there is little doubt that endothelial dysfunction is directly linked to atherosclerosis and cardiovascular disease in patients, whether the endogenous pool of eNOS and associated NO release can be considered a direct, therapeutically relevant primary target for atheroprotection is unknown. Caveolin-1 (Cav-1), the major coat protein of plasma membrane caveolae, binds to and inhibits endogenous eNOS. Previously, we have reported that a Cav-1-derived cell permeable peptide with an inactivated eNOS inhibitory domain, known as CavNOxin is able to increase basal NO release without interfering with the biological activities of Cav-1. Herein the current thesis, I hypothesize that ‘antagonizing’ the eNOS/Cav-1 interaction to specifically relieve eNOS from the inhibitory clamp of Cav-1, through the intracellular delivery of CavNOxin, is a potentially novel and unexplored anti-atherosclerotic therapeutic strategy. I show that CavNOxin is able to significantly attenuate hypercholesterolemia- and diabetes-induced atherosclerosis. In contrast, mice lacking eNOS showed resistance to CavNOxin treatment, indicating eNOS specificity. Mechanistically, I show that CavNOxin reduces oxidative stress, expression of pro-atherogenic mediators (in particular VCAM-1) and leukocyte-endothelial interactions. These data are the first to document the use of an eNOS-specific activator to directly reduce oxidative stress and increase atheroprotective endothelial function specifically through endogenous eNOS. In addition, this study provides target validation for the eNOS/Cav-1 interaction, which is highly endothelium-specific, as a strategy for the development of anti-atherosclerotic compounds.Medicine, Faculty of
Anesthesiology, Pharmacology and Therapeutics, Department of
Graduate
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Lai, Sau-wan, and 賴秀芸. "Investigating beta-amyloid peptide neurotoxicity from neuronal apoptosis to endoplasmic reticulum collapse: translational research back to basic science research." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B41633702.
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Droctove, Laura. "Premières toxines Kunitz antagonistes du récepteur de type 2 à la vasopressine : étude pharmacodynamique et relations structure-activité." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS009/document.
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La mambaquarétine-1 (MQ-1), une toxine du mamba vert, est le tout premier peptide Kunitz à bloquer sélectivement l’activité du récepteur de type 2 à la vasopressine (V2R). Celui-ci contrôle la concentration finale des urines dans le rein. Impliqué dans plusieurs pathologies, son inhibition est actuellement considérée comme la meilleure stratégie thérapeutique dans le traitement de la polykystose rénale, une maladie génétique héréditaire. L’étude pharmacodynamique de MQ-1 sur des rats sains a confirmé son activité in vivo qui se traduit par un effet aquarétique dépendant de la dose. L’effet maximum est atteint 2 heures après injection intrapéritonéale et disparait avec un temps de demi-vie biologique variant de 1 à 4 heures selon la dose. L’administration quotidienne d’une faible dose a montré une accumulation de l’effet les trois premiers jours, avant un plateau, suggérant une activité résiduelle au-delà de 24 heures. Le criblage des trois autres venins de mambas ainsi qu’une analyse comparée des séquences peptidiques les plus proches dans les bases de données ont révélé l’existence d’un groupe phylogénétique de onze toxines Kunitz antagonistes de V2R. Une approche innovante, combinant tests de liaison de variants de MQ-1 et modélisation du complexe MQ-1-V2R, a permis de décrypter une partie du pharmacophore de la toxine. Les deux partenaires partagent une importante complémentarité ionique impliquant plusieurs boucles extracellulaires du récepteur, et une région hydrophobe de MQ-1 interagit au cœur de V2R à proximité de son site orthostérique supposé. Enfin, une première collaboration avec une industrie pharmaceutique a mis en évidence les points critiques à approfondir pour aboutir au développement thérapeutique de MQ-1Mambaquaretin-1 (MQ-1), a green mamba toxin, is the very first Kunitz peptide to selectively hinder the vasopressin type 2 receptor (V2R) activation. This receptor controls the final concentration of urine in kidneys. Involved in a number of pathologies, its inhibition is currently considered as the best therapeutic strategy in the treatment of polycystic kidney disease, a hereditary genetic disease. Pharmacodynamic study of MQ-1 carried out on healthy rats confirmed its in vivo activity which consists in inducing a dose-dependent aquaretic effect. Maximum effect is reached 2 hours after an intraperitoneal injection and disappears in a biological half-life ranging from 1 to 4 hours according to the dose. The daily injection of small quantities pointed to a cumulative effect over the first three days, leading to a plateau, which suggests a residual activity exceeding 24 hours. The screening of the three other mamba venoms along with a comparative analysis of the closest peptide sequences reported in databases revealed the existence of a phylogenetic group of eleven V2R antagonist Kunitz toxins. An innovative approach combining binding assays on MQ-1 variants and the modelling of the MQ-1-V2R complex has led to a partial deciphering of the pharmacophore of the toxin. The two partners share a significant ionic complementarity involving a number of extracellular loops of the receptor, and a hydrophobic region of MQ-1 interacts within V2R in the vicinity of its supposed orthosteric site. Lastly, a collaboration initiated with a pharmaceutical company brought out the need for the closer scrutiny of some crucial points to succeed in a therapeutic development of MQ-1
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Kao, Daniel Joseph. "Development of a synthetic peptide vaccine and antibody therapeutic for the prevention and treatment of Pseudomonas Aeruginosa infection /." Connect to full text via ProQuest. Limited to UCD Anschutz Medical Campus, 2007.
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Thesis (Ph.D. in Pharmacology) -- University of Colorado Denver, 2007.Typescript. Includes bibliographical references (leaves 203-212; 260-261). Free to UCD affiliates. Online version available via ProQuest Digital Dissertations;
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Cozens, Daniel. "The role of tetraspanins in bacterial adhesion to human cells and the therapeutic potential of their peptide fragments." Thesis, University of Sheffield, 2015. http://etheses.whiterose.ac.uk/13256/.
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Tetraspanins are a superfamily of eukaryotic membrane-bound proteins involved in a wide array of cellular processes, such as adhesion and migration. They do this by forming large extended networks on the surface of the cell, known as tetraspanin-enriched microdomains (TEMs), whereby they can act as membrane organisers to partner proteins, including integrins and components of the immune system. This ensures these proteins are in conformations that aid in their function. Many of these partner proteins are also the receptors to which bacteria can adhere, using adhesins. TEMs may cluster these receptors together to allow for multiple interactions between pathogen and host, resulting in firm adhesion. It was shown that by disrupting the TEMs through pre-treatment of epithelial cells with a variety of recombinant tetraspanin extracellular domains (EC2s), it can significantly inhibit the ability of a bacterium to attach to a human epithelial cell line. Chimeric EC2 proteins highlighted important regions of the domain for achieving this phenomenon. This effect was successfully replicated using synthetic peptides based on regions of the CD9 EC2 peptide sequence, in a dose response-like fashion. This has been demonstrated using the bacterial pathogens Neisseria meningitidis, Streptococcus pneumoniae and Staphylococcus aureus. The antimicrobial protection is slowly lost from the cell over time, possibly due to recycling of the tetraspanins from the cell surface. The effect is likely due to disruption of the TEMs, as cholesterol depletion, which similarly disorders TEMs, removes the effect of subsequent treatment with synthetic peptides. EC2s of some tetraspanin molecules (particularly CD9 and CD63) and synthetic peptide derivatives show signs of promise for possible use as anti-adhesion therapeutics for treating bacterial infections. This could possibly be used in conjunction with current antibiotics, providing further protection to the patient during periods of sub-MIC levels of drugs between dosing.
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Arribat, Yoan. "Caractérisation de P42, région cruciale pour la fonction de la Huntingtine et peptide capable d’inhiber la toxicité associée à la Chorée de Huntington." Thesis, Montpellier 2, 2012. http://www.theses.fr/2012MON20140.
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La Maladie de Huntington (MH) reste à ce jour une pathologie neurodégénérative dévastatrice pour laquelle aucun traitement n'est disponible. L'agrégation de la Huntingtine Mutante (Htt PolyQ) joue un rôle majeur dans les processus pathologiques. Dans ce contexte, des études récentes ont démontré que la partie N-terminale de la Huntingtine Humaine (Htt wt) ou de son Homologue drosophile (dHtt) sont toutes deux capables de réduire l'agrégation et la toxicité de Htt PolyQ. En se basant sur cette observation, le travail de thèse décrit dans ce manuscrit a mis au point un découpage du fragment N-terminal de Htt wt de manière à isoler en son sein, une courte séquence de 23 acides aminés (nommée P42), capable d'inhiber spécifiquement l'agrégation de Htt PolyQ en modèle cellulaire. L'effet protecteur de ce peptide a été confirmé in vivo, sur un modèle drosophile de la MH. Le potentiel thérapeutique que représente P42 a servi de point de départ à une étude menée sur le modèle murin R6/2 de la MH. L'effet de P42 a été potentialisé par l'ajout du peptide de transduction TAT de manière à faciliter son entrée dans les cellules cibles. Puis, la protéine fusion P42-TAT a été vectorisée sous forme de microémulsion de manière à assurer à la fois une administration simple de la molécule, et un accès au système nerveux central. Ce protocole original a permis d'observer des bénéfices sans précédent sur les phénotypes comportementaux, histologiques et moléculaires que présentent les souris R6/2.Au-delà de son aspect thérapeutique, P42 est avant tout une séquence méconnue située dans une région cruciale de la Huntingtine. L'étude du rôle physiologique de ce site, a mené à une meilleure compréhension de la fonction sauvage de la protéine toute entière. En outre, une analyse biochimique a montré la capacité du fragment N-terminal de Htt wt à se lier aux microtubules. Cette interaction avec le cytosquelette dépend de plusieurs processus (clivages, dimérisation) et semble affilier la Huntingtine à la grande famille des MAP.L'identification de P42 ouvre donc une voie nouvelle vers la compréhension du rôle physiologique de la Huntingtine, mais représente surtout un espoir thérapeutique captivantHuntington's disease (HD) is a devastating and incurable neurodegenerative disorder. Aggregation processes of mutant Huntingtin (Htt PolyQ) play a central part in the pathology onset. In this context, recent studies pointed out the capacities of wild-type Huntingtin N-terminus to reduce both aggregation and toxicity associated with Htt PolyQ. The drosophila Homologue shares the sames properties. Basing on these observations, the present work realised a cut of human Huntingtin N-terminus in order to identify the region responsible for therapeutic benefits. This screen highlighted a 23 amino-acid sequence (noted P42), that inhibits Htt PolyQ aggregation in a HeLa cells model. Then, the protective effect of this peptide was confirmed in vivo, in a HD drosophila model.P42 therapeutic potential was explored in the R6/2 HD mouse model. The entry of the peptide into cells, was potentialised by grafting to P42, the transduction sequence of TAT. Then, the fusion protein P42-TAT was vectorised in microemulsion, in order to enhance the delivery of the peptide to the brain by resorting to a non-invasive administration way. This original protocol exhibited highly-significant rescues on behavioural, histological and molecular R6/2 phenotypes..Over the therapeutic aspect, P42 also represents an important region of Huntingtin. The study of this site led to a better understanding of Huntingtin physiological function. Biochemestrial experiments underlined the binding of Htt N-terminus on microtubules networks. This interaction depends on a range of complex processes (dimerization, cleavage) and suggests that the Huntingtin belongs to the family of Structual MAPs.In summary, the identification of P42 enhances the knowledge about Huntingtin function, and opens a new promising therapeutical avenue for HD
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Lemkul, Justin Alan. "Molecular Modeling of the Amyloid β-Peptide: Understanding the Mechanism of Alzheimer's Disease and the Potential for Therapeutic Intervention." Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/77318.
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Alzheimer's disease is the leading cause of senile dementia in the elderly, and as life expectancy increases across the globe, incidence of the disease is continually increasing. Current estimates place the number of cases at 25-30 million worldwide, with more than 5.4 million of these occurring in the United States. While the exact cause of the disease remains a mystery, it has become clear that the amyloid β-peptide (Aβ) is central to disease pathogenesis. The aggregation and deposition of this peptide in the brain is known to give rise to the hallmark lesions associated with Alzheimer's disease, but its exact mechanism of toxicity remains largely uncharacterized.
Molecular dynamics (MD) simulations have achieved great success in exploring molecular events with atomic resolution, predicting and explaining phenomena that are otherwise obscured from even the most sensitive experimental techniques. Due to the difficulty of obtaining high-quality structural data of Aβ and its toxic assemblies, MD simulations can be an especially useful tool in understanding the progression of Alzheimer's disease on a molecular level.
The work contained herein describes the interactions of Aβ monomers and oligomers with lipid bilayers to understand the mechanism by which Aβ exerts its toxicity. Also explored is the mechanism by which flavonoid antioxidants may prevent Aβ self-association and destabilize toxic aggregates, providing insight into the chemical features that give rise to this therapeutic effect.Ph. D.
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Yang, Xiaotong, and 楊曉彤. "The anticancer mechanisms of polysaccharide peptide (PSP) derived fromthe Chinese medicinal fungus coriolus versicolor." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B31246229.
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Xie, Haiyan. "The inhibitory activities of constituents of the three main categorites in ginkgo biloba towards amyloidi-ß peptide aggregation." HKBU Institutional Repository, 2014. https://repository.hkbu.edu.hk/etd_oa/68.
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The standard extract of Ginkgo biloba leaves (EGb761) is being clinically used in Europe for the treatment of impaired cerebral function in primary degenerative disorders such as Alzheimer disease (AD) and vascular dementia. The abnormal production and aggregation of amyloid β peptide (Aβ) and the deposition of fibrils in the brain is considered as key steps in the onset of AD. For this reason, the inhibition of Aβ aggregation and the destabilization of preformed fibrils have been identified as effective approaches for the prevention and treatment of AD. EGb761 mainly contains three categories of components: flavonol glycosides (FGs), terpene trilactones (TTLs), and catechins and procyanidins. Among them, only TTLs have been evaluated for the inhibition towards Aβ aggregation, and the effects were much weaker than that of the extract. It was suggested that EGb761 should contain several other compounds that are responsible for this activity. In the current study, we have conducted a comprehensive investigation of the generally chemical and bioactive properties of the compounds belonging to all three of the major component categories present in EGb761. We aimed to identify the compounds responsible for the inhibitory activity exhibited by EGb761 towards Aβ42 aggregation and the destabilization of preformed fibrils. The results can be summarized as follows. Seven major FGs were isolated from EGb761 and determined to be quercetin 3-O-α-(6′′′-p-coumaroyl glucopyranosyl-β-1,2-rhamnopyranoside (1), kaempferol 3-O-α-(6′′′-p-coumaroyl glucopyranosyl-β-1,2-rhamnopyranoside) (2), quercetin 3-O-β-D-rutinoside (3), quercetin 3-O-α-L-(β-D-glucopyranosyl)-(1,2)-rhamnopyranoside (4), isorhamnetin 3-O-β-D-rutinoside (5), kaempferol 3-O-β-D-rutinoside (6), and kaempferol 3-O-α-L-(β-D-glucopyranosyl)-(1,2)-rhamnopyranoside (7) by structural analysis. Four catechins and two procyanidins were also found in EGb761 and identified as catechin, epicatechin, gallocatechin, epigallocatechin, procyanidins B1 and B3. The inhibitory activities of these compounds and four major TTLs (i.e., ginkgolides A, B, and C and bilobalide) towards Aβ42 aggregation were evaluated using a thioflavin T fluorescence assay. The results revealed that catechins and procyanidins compounds exhibited significant inhibitory activities with IC50 values in the range of 3-16 μM, and those of the procyanidins were stronger. Three of the FGs (FG1, FG3 and FG4) showed moderate inhibitory activities, with IC50 values in the range of 30-70 μM, whereas the other four FGs (i.e., FG2, FG5, FG6 and FG7) and the four TTLs showed much weaker activity. The catechins and procyanidins also showed potent activities towards the destabilization of preformed Aβ fibrils. Based on these results, we established several structure-activity relationships (SARs) that specific structural groups, as well as the number and position of hydroxyl groups, the linking sequences of the sugar moieties, and the three dimensional conformations of the compounds were important to their inhibitory activity. We also established quantitative analysis of all these tested compounds and simultaneously determined their contents in the Ginkgo extracts. In addition, total FGs, total TTLs, and total catechins and procyanidins were prepared by column chromatography. Similarly, they were also quantitatively analyzed and their inhibitory activities towards Aβ42 aggregation were evaluated. The results showed that total catechins and procyanidins exerted much stronger activity than total FGs and total TTLs. Comprehensive assessment of their activities and contents in the extract indicated that the contribution of the FGs was almost twice that of the catechins and procyanidins, which indicated that they played an important role in the effect of the extract. TTLs alone could barely contribute to the EGb’ effect and probably exerted their influence through the synergistic effect with FGs, which was speculated from the study. In conclusion, the current study has shown that the catechins and procyanidins present in EGb761 possessed potent ability to inhibit Aβ aggregation and destabilize preformed fibrils. FGs made a significant contribution to EGb761’s inhibitory activity towards Aβ aggregation and its neuroprotective effects. Furthermore, the SAR study provide evidences for further research and development of Ginkgo products and drugs designed to target Aβ aggregation or the destabilization of preformed fibrils. Despite their low contents in EGb761 and related products, catechins and procyanidins, and even proanthocyanidins deserve further study because of their potent effects towards Aβ aggregation and the destabilization of preformed fibrils, which could have a significant impact on the quality control of Ginkgo leaves and Ginkgo products.
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Edwards, Danielle Nichele. "INTEGRIN α5β1 AS A NOVEL TARGET WITH THE SMALL PEPTIDE, ATN-161, IN THE TREATMENT OF ISCHEMIC STROKE." UKnowledge, 2019. https://uknowledge.uky.edu/neurobio_etds/21.
Full textAbstract:
Stroke is the 5th leading cause of death and the leading cause of disability in the United States, but there are only two available therapies, tissue plasminogen activator and endovascular thrombectomy. As both therapies focus on removal of the clot, the subsequent pathologic processes, i.e. inflammation, cerebrovascular breakdown, ATP depletion, etc. are left untreated, contributing to worsened patient outcome. Many clinical trials have unsuccessfully attempted to address these mechanisms. The blood-brain barrier (BBB), a system of non-fenestrated endothelial cells, extracellular matrix, and astrocytic endfeet, is significantly impacted after ischemic stroke in its role of preventing the free movement of proteins from the blood into the brain. In fact, BBB dysfunction is viewed as one of the major facilitators of damage following ischemic stroke, leading to increased infarct volumes and worsened patient outcomes. Interestingly, a family of endothelial integrins, the b1 integrins, have been shown to regulate tight junction proteins preventing the free movement of molecules. When expression of the tight junctions are decreased, this results in increased BBB permeability. To test this concept, our laboratory has previously shown the knockout of the particular β1 integrin, α5β1, is neuroprotective following ischemic stroke through BBB stabilization.
To determine if therapeutically targeting integrin a5b1 was feasible, we first determined if brain integrin a5b1 expression increases after experimental mouse ischemic stroke model, specifically tandem/transient common carotid artery/middle cerebral artery occlusion. We found that integrin a5b1 does increase acutely, by post-stroke day (PSD)2, and continued in an exponential fashion through PSD4. Next, we determined if integrin a5b1 was therapeutically accessible by systemic treatment (i.e. intraperitoneal or intravenous) by being located on the inside (luminal surface) of vasculature. We found that location of integrin a5b1 was dependent on the area relative to the stroke injury. The core, or area of direct impact, demonstrated expression of integrin a5b1 on the outside vasculature (abluminal surface), while per-infarct expression was localized to the lumen. Lastly, to determine the activity of integrin a5b1 following ischemic stroke, we showed that the potential ligands (binding partners), plasma fibronectin, fibrinogen, and amyloid-b, do not bind integrin a5b1 after ischemic stroke.
Next, we determined the therapeutic potential of targeting integrin a5b1 with the small peptide, ATN-161. ATN-161 has undergone clinical trials in solid tumors, with limited side effects reported. First, we determined that intraperitoneal (IP) injection of ATN-161 was safe after ischemic stroke, showing no changes in heart rate, pulse distention (blood pressure), or body temperature. Next, we found that IP administration of ATN-161 after experimental ischemic stroke reduced infarct volumes, edema, and functional deficit. Furthermore, these results were due to reduction of BBB permeability and anti-inflammatory effects. Interestingly, ATN-161 reduced cytokine production, prevented leukocyte infiltration, and leukocyte recruitment. Collectively, these results suggest that targeting integrin a5b1 with ATN-161 is 1) feasible, 2) safe and 3) effective, suggesting that ATN-161 may be a novel therapeutic treatment for ischemic stroke.
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Faivre, Emilie. "The role of glucose-dependent insulinotropic peptide signalling in the normal brain and therapeutic effects in an Alzheimer's disease mouse model." Thesis, University of Ulster, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.588493.
Full textAbstract:
Alzheimer's disease (AD) is a neurodegenerative disease, characterized by cognitive impairments and occurrence of neuronal depositions of amyloid plaques. At present, no treatment for AD is known. A disturbance in insulin signaling and its receptor was recently highlighted in the brain of AD patients. In this study, the effect of glucose- dependent insulinotropic peptide (GIP) was investigated in the brain, as it is a potential candidate to activate a parallel signaling pathway to insulin. The lack of GIP receptor affects learning and memory in object recognition and Morris water maze tasks, synaptic plasticity and progenitor cell proliferation in the hippocampus of GIP receptor knockout mice. Effects of long-lasting GIP analogues were investigated on different physiological processes in the brain. D-Ala2GIP agonist at 25 nmol/kg seems to be the most effective dose after chronic administration in normal mice and no adverse side effects were observed. The antagonist (Pr03)GIP impaired memory formation after acute administration, while beneficial effects were observed on learning and synaptic plasticity following chronic application. The potential beneficial effects of D-Ala2GIP treatment on AD pathology were tested in mouse model of AD (APPIPS 1 mice) aged 6, 12 and 19 months old and wild-type age matched mice, that were injected daily with D-Ala2GIP for 21 days. This treatment preserved synaptic function of 12 month-old APP/PSl mice and old WT mice, leading to improvement of long-term potentiation and learning and memory, and protects synapses against degeneration. D-Ala2GIP reduced the number of plaques and inflammation in the cortex of APP /PS 1 mice. The beneficial action of GIP was potentiated by a longer and earlier treatment. In both 6 month-old and 11 month-old APPIPSI mice, daily treatment for 14 week and 34 week, respectively, D-Ala2GIP prevented synapse loss and reduced the number of plaque load and inflammation in the brain. These results suggest that GIP analogues may be an attractive therapeutic approach for the treatment of neurodegenerative diseases.
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Shukeir, Nicholas. "Molecular mechanism(s) of prostate cancer progression : potential of therapeutic modalities." Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=115853.
Full textAbstract:
Prostate cancer remains one of the most commonly diagnosed cancers in men and is a leading cause of cancer death. While great success has been achieved at curing early stage prostate cancer, limited success has been obtained when treating late-stage hormone independent prostate cancer. This is due to the increased propensity for skeletal and non-skeletal metastases. Thus development of novel effective therapeutic modalities against late stage prostate cancer is of critical importance.Towards these objectives, I have focused my attention on the role of prostate secretory protein (PSP-94) which is expressed in normal individuals and in patients with early stage prostate cancer. Using our well established in vivo models of prostate cancer, I have evaluated the ability of PSP-94 and its amino acids 31-45 required (PCK3145) to decrease tumor growth and skeletal metastases in vivo and evaluated the potential mechanism(s) associated with PCK3145 anti-cancer actions.
Prostatic cancer can also develop as a result of epigenetic activation of tumor promoting genes. To evaluate the role of methylation in prostate cancer, late stage prostate cancer cells were treated with the universal methylating agent S-adenosylmethionine (SAM) and an anti-sense oligonucleotide directed against MBD2 (AS). Scrambled oligonucleotide was included as a control (S). Both SAM and MBD2-AS resulted in inhibition in uPA, MMP-2 and VEGF production leading to decreased tumor cell invasive capacity. However, SAM and MBD2-AS were not able to either further repress partially methylated genes (GSTP1) or reactivate already methylated genes (AR). Furthermore, SAM and MBD2-AS treatment resulted in significant reduction in tumor growth in vivo . Immunohistochemical and RT-PCR analyses carried out on SAM and MBD2-AS tumors revealed decreased protein and mRNA expression of uPA and MMP-2 which was partially due to increased methylation of the respective promoters even after 10 weeks post in vitro treatment as analyzed by bisulfate sequencing. In addition decreased levels of angiogenesis and tumor survival markers were observed.
Collectively, these studies are aimed at the development of novel reliable approached to diagnose and treat advanced, hormone refractory prostate cancer to reduce tumor associated morbidity and mortality.
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Tam, Joseph. "Effect of Islet Neogenesis Associated Protein (INGAP) peptide on axonal regrowth in the peripheral sensory nervous system and its therapeutic implications for diabetic peripheral neuropathy." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=103186.
Full textAbstract:
The majority of individuals with .long-term diabetes become afflicted with diabetic peripheral neuropathy (DPN), an often painful and debilitating secondary complication of the disease. Symptomatic treatments, which do not address the underlying nerve damage in diabetes, are currently the only therapeutic options for DPN, aside from rigorous control of blood glucose, which only occasionally reduces the incidence and severity of DPN. Given the progressive nature of disorder, and the failure of the classical neurotrophins in clinical trials for DPN, it is important to develop new therapeutics that can counteract the nerve damage in diabetes.Pancreas-derived peptides that stimulate islet regeneration have gained increasing interest for use in DPN, in part due to the unique similarities that exist between pancreatic and neural tissues. We studied the effects of one such peptide, the Islet Neogenesis Associated Protein (INGAP) peptide, on axonal regrowth in the peripheral nervous system (PNS) in adult C57BLJ6 mice. Using dorsal root ganglia (DRG) explant cultures as in vitro model of axotomy, we found that INGAP peptide enhances axonal regrowth in a time- and concentration-dependent manner that involves cyclic AMP-dependent activation of protein kinase A (PKA) and stimulation of phosphatidylinositol-3 kinase (PI3K). The neuritogenic effects of INGAP peptide were reduced by blocking antibodies against a number of growth factors that are secreted by Schwann cells including nerve growth factor (NGF), insulin-like growth factor-I (IGF-I) and transforming growth factor-beta (TGF-(3), suggesting an indirect action of INGAP peptide on outgrowth from DRG neurons, achieved via a primary action on Schwann cells.
To further assess the potential usefulness of INGAP peptide in DPN, we used streptozotocin-induced type 1 diabetic mice and found that after two weeks of INGAP peptide administration, begun twelve weeks after the STZ treatment, sensory dysfunction (reduced sensitivity to heat stimulation) was corrected without inducing the hyperalgesia associated with direct administration of NGF. These effects were accompanied by increases in the levels of a number of structural proteins and transcription factors associated with nerve growth. Significantly, the beneficial effects of INGAP peptide on the PNS in vivo occurred independently of its normalizing effects on hyperglycemia. Finally, we found that INGAP peptide enhanced the mitochondrial inner transmembrane potential (DeltaPsim), and that the mitochondrial effects were largely mediated by PKA.
Taken together, these studies demonstrate that INGAP peptide enhances sensory axonal regrowth independently of islet neogenesis and the consequent secretion of insulin, and that it may be of benefit in the treatment of peripheral neuropathy associated with diabetes and possibly other clinical conditions.
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Rossetto, Nicolas. "Optimisation de l'effet radiobiologique d'un traitement de radiothérapie interne vectorisée des tumeurs neuroendocrines." Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30223.
Full textAbstract:
Les médicaments radiopharmaceutiques ciblant les récepteurs peptidiques tels que les analogues de la somatostatine ont un réel potentiel et un fort intérêt pour à la fois le diagnostic et le traitement des tumeurs neuroendocrines (TNE) non-opérables, par radiothérapie interne vectorisée (RIV). La toxicité des traitements par radiopeptides analogues de la somatostatine limite leur développement clinique. Le développement de nouveaux peptides ciblant d'autres types de récepteurs tels que le ceux de la cholécystokinine (CCK) est une solution dont l'intérêt a été montré par les travaux de notre équipe, basés sur un analogue CCK novateur. Ce travail en trois volets décrit dans un premier temps le radiomarquage de l'analogue CCK, par des radionucléides émetteurs - tels que l'yttrium 90 et le lutétium 177 adaptés à la thérapie, en plus de l'indium 111 pour le diagnostic, les capacités de complexation et la stabilité de ce nouvel analogue peptidique CCK. Une étude in vivo préliminaire sur modèle murin a permis d'étudier la faisabilité d'un traitement de RIV. Une troisième étude a été réalisée in vitro sur deux lignées cellulaires tumorales par le traitement à l'aide d'une molécule antitumorale caractérisée dans notre équipe, à travers la réexpression d'une voie de signalisation cellulaire. Ce travail a permis de montrer l'intérêt potentiel de l'utilisation des analogues CCK en RIV en association thérapeutique pour la prise en charge de certaines TNELes médicaments radiopharmaceutiques ciblant les récepteurs peptidiques tels que les analogues de la somatostatine ont un réel potentiel et un fort intérêt pour à la fois le diagnostic et le traitement des tumeurs neuroendocrines (TNE) non-opérables, par radiothérapie interne vectorisée (RIV). La toxicité des traitements par radiopeptides analogues de la somatostatine limite leur développement clinique. Le développement de nouveaux peptides ciblant d'autres types de récepteurs tels que le ceux de la cholécystokinine (CCK) est une solution dont l'intérêt a été montré par les travaux de notre équipe, basés sur un analogue CCK novateur. Ce travail en trois volets décrit dans un premier temps le radiomarquage de l'analogue CCK, par des radionucléides émetteurs - tels que l'yttrium 90 et le lutétium 177 adaptés à la thérapie, en plus de l'indium 111 pour le diagnostic, les capacités de complexation et la stabilité de ce nouvel analogue peptidique CCK. Une étude in vivo préliminaire sur modèle murin a permis d'étudier la faisabilité d'un traitement de RIV. Une troisième étude a été réalisée in vitro sur deux lignées cellulaires tumorales par le traitement à l'aide d'une molécule antitumorale caractérisée dans notre équipe, à travers la réexpression d'une voie de signalisation cellulaire. Ce travail a permis de montrer l'intérêt potentiel de l'utilisation des analogues CCK en RIV en association thérapeutique pour la prise en charge de certaines TNE
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Santos, Tânia Raquel Martins dos. "Novel therapeutic strategies for the management of diabetic foot infections : the evaluation of selected antimicrobial peptides against clinically isolated bacterial pathogens." Doctoral thesis, Universidade de Lisboa, Faculdade de Medicina Veterinária, 2020. http://hdl.handle.net/10400.5/20150.
Full textAbstract:
Tese de Doutoramento em Ciências Veterinárias na Especialidade de Ciências Biológicas e BiomédicasDiabetic foot infections (DFIs) are a frequent complication of Diabetes mellitus. These ulcers are prone to be colonized by Staphylococcus aureus and Pseudomonas aeruginosa, including multidrug resistant and biofilm-producing strains, possibly leading to DFI chronicity and amputation. New therapeutic strategies for DFI management are urgent and the antimicrobial peptides (AMPs) nisin and pexiganan are potential candidates. This project aimed to evaluate the activity of these AMPs, incorporated in a guar gum biogel, against selected DFI clinical isolates. Firstly, nisin’s activity against a collection of S. aureus DFI clinical isolates was determined. Results showed that nisin was able to inhibit and eradicate S. aureus planktonic and biofilm cells at concentrations below its acceptable daily intake. When incorporated in the biogel, nisin kept its antimicrobial activity. This work also evaluated the potential of nisin to complement the activity of conventional antiseptics and antibiotics against established biofilms formed by these isolates. An in vitro antimicrobial schematic protocol was developed to mimetize DFI management guidelines. Fifteen antimicrobial combinations, including nisin-biogel, chlorhexidine, clindamycin, gentamicin and vancomycin, were tested. Results showed that the higher levels of biofilm inhibitory effects were presented by therapeutic combinations that included the nisin-biogel formulation. Nisin-biogel ideal storage conditions and cytotoxicity were also evaluated. Results demonstrate that if stored at temperatures between -20 and 22ºC, nisin-biogel is able to maintain its antimicrobial activity up to 24 months. Moreover, after 24 h of exposition, the nisin-biogel presented no significant levels of toxicity regarding the human keratinocytes under study. Lastly, to cover the complex microbiota present in DFIs, a combination of AMPs with different action spectra was developed, based on the simultaneous incorporation of nisin and pexiganan in the biogel. The activity of this dual-AMPs formulation was tested against two S. aureus and P. aeruginosa strains isolated from the same DFI. Acting together, these AMPs were able to diffuse from the biogel and inhibit and eradicate biofilms formed by these DFI isolates. The effectiveness of AMPs, particularly nisin and pexiganan, as novel antimicrobial strategies for the management of DFIs is still an unknown territory that merits investigation. In vitro biofilm models are the basis of preliminary research; however, they underrepresent the complex microbiota present in DFIs and their interaction with the immune system and skin cells constituents. Further research is necessary to understand the AMPs full potential regarding the clinical management of biofilm-related diseases, such as DFIs.
RESUMO - As infecções do pé diabético (IPDs) são uma complicação frequente da Diabetes mellitus. Estas úlceras tendem a ser colonizadas por Staphylococcus aureus e Pseudomonas aeruginosa, incluindo estirpes multirresistentes e produtoras de biofilme, possivelmente causando cronicidade da IPD e amputação. É urgente criar novas estratégias para o tratamento das IPD e os péptidos antimicrobianos (PAMs) nisina e pexiganan são potenciais candidatos. Este projecto avaliou a actividade destes PAM, incorporados num biogel de goma de guar, contra isolados de IPD. Primariamente, foi determinada a actividade da nisina contra uma colecção de S. aureus isolados de IPD. Os resultados mostraram que a nisina é capaz de inibir e erradicar S. aureus na forma planctónica e de biofilme a concentrações abaixo da dose diária recomendada. Quando incorporada no biogel, a nisina manteve a sua actividade. Foi ainda avaliado o potencial da nisina para complementar a actividade de antissépticos e antibióticos convencionais contra biofilmes formados por estes isolados. Foi criado um protocolo que simula in vitro o tratamento convencional das IPDs. Foram testadas 15 combinações de antimicrobianos, incluindo biogel de nisina, clorohexidina, clindamicina, gentamicina e vancomicina. Os resultados mostraram que o maior efeito inibidor de biofilmes pertencia a combinações que incluam o biogel de nisina. Foram também avaliadas as condições de armazenamento ideais para o biogel de nisina e a sua citotoxicidade. Quando armazenado a temperaturas entre -20 e 22ºC, o biogel de nisina manteve a sua actividade antimicrobiana durante pelo menos 24 meses. Adicionalmente, após exposição durante 24 horas, o biogel de nisina não apresentou níveis significativos de toxicidade relativamente aos queratinócitos humanos em estudo. Por último, para abranger a complexa microbiota presente nas IPDs, foi avaliada uma combinação de PAMs com diferentes espectros de acção, baseada na incorporação simultânea de nisina e pexiganan no biogel. A actividade desta formulação foi testada contra duas estirpes de S. aureus e P. aeruginosa isoladas da mesma IPD. Conjuntamente, estes PAMs foram capazes de se difundir do biogel e inibir e erradicar biofilmes formados por estes isolados. A eficácia dos PAMs como novas estratégias para o tratamento das IPD é ainda uma área desconhecida. Os modelos in vitro de biofilmes são a base da investigação; contudo, não representam a microbiota presente nas IPD nem a sua interacção com o sistema imunitário e outros constituintes celulares. É essencial continuar a investigar para compreender o potencial dos PAMs na terapêutica de doenças onde haja formação de biofilmes, como é o caso das IPDs.
N/A
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Gibson, Meghan E. "Examining the Role of Magnesium Ions in the Structural Stability of Ribosomal Subunits and An Investigation of a Novel Anticancer Therapeutic: Analyzing the Binding Affinity of a Stapled p53 Peptide Analog for Regulator MDM2." Thesis, Boston College, 2011. http://hdl.handle.net/2345/bc-ir:104431.
Full textAbstract:
Thesis advisor: Udayan MohantyComputational research can play a crucial component in the discovery of unique biochemical phenomena, from answering fundamental questions about molecular function and structure to the modeling of designed pharmaceuticals to cure many debilitating illnesses. Here computational methods are employed to examine the exquisite role that magnesium ions play in stabilizing ribosomal subunits responsible for protein translation and to analyze the potential of a proposed anticancer drug for a pathway that is impaired in the majority of human cancer cases
Thesis (BS) — Boston College, 2011
Submitted to: Boston College. College of Arts and Sciences
Discipline: College Honors Program
Discipline: Chemistry
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Ungurs, Michael J. "Molecular recognition of peptides : basis for design and delivery of peptide therapeutics." Thesis, Bangor University, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.409465.
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Lopez, Aguilar Aime. "Peptides as therapeutics." Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:d893e962-5cb9-4d50-bbe1-c5183418295c.
Full textAbstract:
Peptides have attracted increasing attention as therapeutics in recent years, at least partially as a consequence of the widespread acceptance of protein therapeutics; but also as possible solutions to problems such as short half-life and delivery of molecules, and as therapeutics in their own right. The current work presents three projects that involve applications of peptides in a therapeutic environment. The first project studies the use of ER retaining peptides and CPPs (Cell penetrating peptides) in enhancing the effective concentration of DNJ (1-deoxynojirimycin), an α-glucosidase inhibitor, in cells. DNJ constructs with ER retaining peptides (6-[N-(1-deoxynojirimycino)]-hexanoyl-KDEL and 6-[N-(1-deoxynojirimycino)]-hexanoyl-KKAA) and CPPs (6-[N-(1-deoxynojirimycino)]-hexanoyl-TAT and 6-[N-(1-deoxynojirimycino)]-hexanoyl-MAP) were synthesised and analysed for their inhibitory activity against α-glucosidase I and II in vitro. The constructs were then analysed in a cell-based assay to determine their inhibitory activity on α¬-glucosidase-mediated hydrolysis of N-linked oligosaccharides. FITC-labelled ER retaining peptides were also synthesised to determine the internalisation and trafficking of the constructs by FACS and IF-microscopy. While none of the DNJ-constructs showed higher cellular inhibition than NB-DNJ (N-butyl DNJ; Miglustat), the CPP construct 6-[N-(1-deoxynojirimycino)]-hexanoyl-TAT showed comparable activity and the ER retaining construct 6-[N-(1-deoxynojirimycino)]-hexanoyl-KDEL showed a small but significant increase in activity following long-term administration. The second project focuses on beauveriolides, a cyclic depsipeptide family shown to have activity as ACAT inhibitors and thus a possible treatment for Alzheimer’s disease by the decrease in the production of Amyloid β (Aβ). A published total synthetic method was improved by the use of a cross-metathesis to reduce the total synthesis by 5 steps and increase its flexibility to allow the production of analogues. The synthesised beauveriolide III was used in attempts to develop an IF-FACS-based assay to measure the intracellular concentrations of Aβ. However, the location of γ-secretase in the used cell-line meant that levels of intracellular Aβ were not sufficient to track any decrease caused by ACAT inhibition. The third project involves the design of a cyclic peptide that could block the binding site for the influenza virus in the host cell. The cyclic peptide (cGSGRGYGRGWGVGA) was developed from a comparative study of four different sialic acid-binding proteins and synthesised by solution cyclisation of the linear peptide synthesised by traditional solid phase peptide synthesis (SPPS). An in silico study showed that the cyclic peptide allowed overlap with the binding site of Hemagglutinin. A 1H NMR titration determined the dissociation constant of the cyclic peptide to sialic acid. The KD corresponded to a low binding affinity, however the observed binding seemed to be specific and caused by a single bound conformation.
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Maherzi-Mechalikh, Chahrazed. "Optimisation des vaccins thérapeutiques induisant des réponses T CD8+ spécifiques d’antigènes tumoraux : étude de l’induction des lymphocytes T régulateurs après vaccination." Thesis, Sorbonne Paris Cité, 2017. http://www.theses.fr/2017USPCB035.
Full textAbstract:
La détection de lymphocytes T (LT) CD8+ infiltrant les tumeurs (TIL), est généralement associée à un bon pronostic chez des patients atteints du cancer. A l’inverse, l'infiltration des tumeurs par des LT CD4+ régulateurs (Treg), est quant à elle, souvent corrélée à un mauvais pronostic. Plusieurs vaccins « thérapeutiques » capables d’induire des réponses T CD8+ spécifiques d’antigènes tumoraux ont été développés. Cependant, à ce jour, les résultats cliniques obtenus par ces vaccins restent décevants. Dans un premier travail, nous avons développé puis testé un vaccin thérapeutique composé de trois longs peptides synthétiques (LSP) dérivés de la protéine survivine (SVX). La survivine est une protéine surexprimée dans la majorité des cancers humains, mais absente dans les tissus adultes sains, ce qui fait d’elle une cible thérapeutique privilégiée pour les vaccins anti-tumoraux. Nous avons démontré l'efficacité thérapeutique élevée du vaccin SVX contre diverses tumeurs murines. Ceci a été associé à l'induction de réponses T spécifiques de la survivine, un prolongement de la survie et la génération de réponses mémoires antitumorales. De plus, SVX a induit à la fois des LT CD8+ cytotoxiques spécifiques et LT CD4+ auxiliaires de type 1 multifonctionnelles, dans la rate et au sein des tumeurs. Il a aussi induit une diminution des Treg, favorisant ainsi une réponse immunitaire très efficace. Enfin, une étude préliminaire menée chez des patients atteints de différents types de cancers, nous a révélé la présence de taux élevés de précurseurs spontanés de LT spécifiques du vaccin SVX. Ces résultats suggèrent que SVX pourrait potentiellement stimuler l'activation de ces précurseurs spécifiques. Ces résultats constituent une preuve de concept pour amener ce vaccin comme un produit de première génération en essai clinique chez l’homme. Dans le but d’étudier plus en détails la cinétique des réponses immunitaires T spécifiques, associées aux vaccins LSP, nous avons étudié dans un second travail, l’efficacité d’un vaccin LSP dérivé de la protéine Ovalbumine (OVA). Nous avons montré dans plusieurs modèles de tumeurs murines, que la combinaison du vaccin LSP-OVA à un adjuvant approprié, induisait une forte régression de la croissance tumorale, l’expansion des cellules spécifiques T CD4+ et T CD8+ dans les organes lymphoïdes, ainsi que leur migration vers les tumeurs. De plus, le vaccin a induit des cellules T spécifiques fonctionnelles, comme le témoignent les niveaux élevés de cytokines cytotoxiques mesurées. De manière intéressante, le vaccin n’a pas induit de Treg spécifiques d’OVA ou de Treg polyclonaux et ce, malgré la présence de la tumeur. Enfin, lorsque LSP-OVA ne parvenait pas à induire une régression complète de la tumeur, celle-ci était infiltrée par des TIL CD4+ conventionnels et CD8+ exprimant fortement les récepteurs inhibiteurs (PD-1, TIM-3 et TIGIT). Nos résultats suggèrent que pour optimiser ce vaccin LSP, une association à des anticorps bloquant un ou plusieurs de ces récepteurs inhibiteurs, devrait être envisagéeThe presence of tumor-infiltrating CD8+ T lymphocytes (TIL) is generally associated with a good prognosis in cancer patients. Conversely, the infiltration of tumors by CD4+ regulators T cells (Treg), is often associated with poor prognosis. Several "therapeutic" vaccines able to induce tumor-specific CD8+ T cell responses have been developed. However, to date, the clinical results of these vaccines remain insufficient. In a first work, we developed and analyzed the immunogenicity and therapeutic efficacy of a new survivin vaccine (SVX) composed of three long synthetic peptides (LSP) containing several CD4 and CD8 T-cell epitopes. Survivin is over-expressed by most human cancers, but absent in healthy adult tissues, making it an interesting therapeutic target for cancer vaccines. We demonstrated the high therapeutic efficacy of SVX vaccine against various established murine tumor models, associated with its capacity to generate both specific cytotoxic CD8+ and multifunctional Th1 CD4+ T-cell responses but also effective memory T-cell responses for long-term protection against relapses. Treatment with SVX vaccine was also found to strongly increase the tumor infiltration of both CD4+ and CD8+ T cells over Treg cells therefore tipping the balance toward a highly efficient immune response. Finally, a preliminary study in patients with different types of cancer revealed the presence of high levels of SVX-specific spontaneous T-cell precursors. This suggests that SVX can potentially stimulate the activation of these specific precursors. Altogether, our results strongly suggest that SVX is a promising cancer vaccine and warrants its further clinical development. In order to study the kinetics of tumor-specific immune responses associated with LSP vaccines, we studied the efficacy of a LSP vaccine derived from the Ovalbumin (OVA) protein. We showed in two tumor models that the combination of LSP-OVA with a suitable adjuvant induced a strong tumor regression, an important expansion of both OVA-specific CD4+ and CD8+ T cells in the lymphoid organs, as well as their migration to the tumor. In addition, the vaccine induced functional specific T cells, as shown by the high levels of cytotoxic cytokines. Interestingly, the vaccine did not induce either OVA-specific or polyclonal Treg, despite the presence of the tumor. Finally, when LSP-OVA failed to induce a complete depletion of the tumor, we observed an important expression of inhibitory receptors (PD-1, TIM-3 and TIGIT) on conventional CD4+ and CD8+ TIL. Our results suggest that to optimize this LSP vaccine, a combination with one or more immune checkpoint blockade agents should be considered
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Gamper, Coralie. "Nanoparticules dérivées de virus de plante pour le traitement et l'imagerie du cancer." Thesis, Strasbourg, 2019. http://www.theses.fr/2019STRAJ038/document.
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Les possibilités de combinaison thérapeutiques offertes par les nanoparticules ont ouvert un nouveau champ d’investigation pour la recherche sur le cancer. Dans ce projet de recherche, des nanoparticules dérivées de la protéine de capside du virus de la mosaïque du tabac (TMV) ont été utilisées afin de transporter différents peptides thérapeutiques ciblant le récepteur neuropiline-1. Cette stratégie a permis de solubiliser un peptide fortement hydrophobe ayant préalablement démontré son efficacité anticancéreuse sur des lignées de cancer du sein humain et de glioblastome. Les résultats obtenus ont également permis de démontrer la possibilité de combiner différents peptides thérapeutiques via l’auto-assemblage de la protéine de capside du TMVNanoparticles play an ever increase role in carrying therapeutic compounds in the cancer field. In this research project, the coat protein of Tobacco mosaic virus (TMV) was used as nanocarrier to solubilize a hydrophobic peptide interfering with the transmembrane domain of neuropilin-1. The nanoparticles created have conserved the antiangiogenic and antimigratory effect of the therapeutic peptide. This strategy was also used to create nanoparticles carrying a peptide targeting the ectodomain of neuropilin-1. The two types of nanoparticles were then assembled through auto-assembling ability of the coat protein. These nanoparticles also exhibit antiangiogenic ability thus, confirming the validity of this approach to combine therapeutic peptides
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Jacob, Laurent. "Propriétés anti-angiogéniques et anti-migratoires de peptides transmembranaires ciblant le complexe neuropiline-1/plexine-A1 dans le glioblastome." Thesis, Strasbourg, 2013. http://www.theses.fr/2013STRAJ064/document.
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Ce travail poursuit l’exploration du potentiel thérapeutique de peptides antagonistes des domaines transmembranaires (TM) de récepteurs impliqués dans la croissance tumorale. J’ai montré l’effet anti-angiogénique de MTP-NRP1, un peptide ciblant le récepteur Neuropline-1 et confirmé sa capacité d’inhibition de prolifération, migration et de croissance d’une lignée de glioblastome (GBM) humain. J’ai ensuite démontré que le récepteur Plexine-A1 est corrélé à l’agressivité des gliomes et semble être un marqueur pronostique négatif de la survie des patients atteints de GBM. J’ai démontré le rôle du segment TM de PlexA1 dans ses interactions. Le peptide MTP-PlexA1, inhibe la signalisation et la formation du complexe NRP1-PlexA1, réduit la prolifération et la migration des cellules de GBM, impacte la croissance tumorale in vivo y compris de cellules souches tumorales. J’ai décrit le rôle pro-angiogénique de PlexA1 par des tests d’angiogenèse et de CAM où MTP-PlexA1 bloque cette fonctionThis thesis work continues the exploration of the therapeutic potential using peptides targeting transmembrane (TM) domains of receptors involved in tumor growth. I showed the anti-angiogenic effect of MTP-NRP1, a peptide targeting Neuropilin-1 and confirmed its capability to impact proliferation, migration and in vivo growth of a human glioblastoma (GBM) cell line. Then, I demonstrated that the expression of Plexin-A1 is correlated with glioma aggressiveness and seems to be a bad prognosis marker for GBM patients. We described the importance of PlexA1 TM domain in the control of their interactions. The peptide MTP-PlexA1 inhibits complex formation and signaling of NRP1-PlexA1, impacts tumor growth in vivo and cancer stem cells engrafting and development. I demonstrated the pro-angiogenic role of PlexA1 with in vitro angiogenesis assays and CAM assay in which MTP-PlexA1 is able to block this function
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Seisel, Quentin. "Développement et vectorisation de peptides inhibiteurs du domaine PDZ de CAL pour le traitement de la mucoviscidose." Thesis, Montpellier, 2018. http://www.theses.fr/2018MONTT010/document.
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La mucoviscidose est une maladie génétique létale induite par des mutations du canal ionique CFTR, provoquant une perte de sa fonctionnalité au niveau des tissus épithéliaux de divers organes. Le poumon est particulièrement touché et devient sujet à des infections bactériennes chroniques. Dans le but de traiter la maladie, nous avons développé des « stabilisateurs » de la protéine CFTR : il s’agit de peptides inhibant l’interaction de la protéine CFTR avec le médiateur-clé de sa demi-vie à la membrane apicale des cellules épithéliales, la protéine CAL. En particulier, le peptide iCAL36 a démontré une hausse de fonctionnalité de la protéine CFTR mutée. Le but de cette thèse a été de renforcer cet effet biologique en améliorant ses caractéristiques pharmacologiques : pénétration cellulaire (vectorisation), stabilité métabolique et affinité pour la protéine CAL.Le premier axe d’optimisation a été l’internalisation du peptide iCAL36 par 7 différents peptides vecteurs (CPP). Les conjugués correspondants ont été évalués suivant leur cytotoxicité, leur efficacité d’internalisation et leur capacité à maintenir cette efficacité en présence de sérum. Le mécanisme d’entrée des deux meilleurs conjugués a ensuite été étudié. Divers biais couramment rencontrés lors de l’analyse de l’efficacité d’internalisation de peptides vecteurs par des méthodes de fluorescence ont également été identifiés et expliqués. La séquence du peptide iCAL36 a ensuite été modulée par inclusion d’acides aminés non-naturels. Le criblage des interactions peptide/protéine a été réalisé par une procédure optimisée dans le cadre de cette thèse (méthode PIPEPLUS) et a permis d’identifier 32 analogues prometteurs de la séquence d’iCAL36 incluant différentes substitutions. En particulier, une des séquences identifiées (iCAL-Q27) a démontré une affinité 70 fois supérieure à celle du peptide iCAL36 pour la protéine CAL, indiquant une inhibition plus complète de l’interaction CAL/CFTR.Ces résultats majeurs permettent dans leur ensemble de développer des « stabilisateurs » peptidiques de seconde génération pouvant avoir un effet biologique accru dans le contexte de la mucoviscidoseCystic fibrosis is a lethal disease induced by genetic mutations of the CFTR chloride channel, leading to a loss of its function in the epithelial tissues of various organs. The lung is particularly affected and becomes a target for chronical bacterial infections. To cure the disease, we developed so-called CFTR “stabilizers”, which are peptides inhibiting the interaction between the CFTR protein and the key mediator of its half-life at the apical membrane of epithelial cells, the CAL protein. In particular, the iCAL36 peptide showed an increase of the functionality of the mutated CFTR protein. The aim of this thesis was to increase this biological effect by improving its pharmacological parameters: cellular internalization (vectorization), metabolic stability and affinity for the CAL protein.The first axis of optimization was the internalization of the iCAL36 peptide by 7 different cell-penetrating peptides (CPP). The corresponding conjugates were evaluated upon their cytotoxicity, their uptake efficiency and their capacity to maintain this efficiency in the presence of proteases. The mechanism of entry of the two best candidates was then studied. Various bias frequently encountered during the analysis of CPP uptake efficiency by fluorescence methods were also identified and explained. Afterwards, the iCAL36 sequence was modulated by inclusion of non-natural amino acids. The screening of the peptide/protein interactions was performed by a method optimized during this thesis (PIPEPLUS process) and allowed the identification of 32 promising analogues of the iCAL36 sequence including several substitutions. In particular, one of these sequences (iCAL-Q27) showed an affinity 70 times stronger for the CAL protein compared to iCAL36, hinting a more complete inhibition of the CAL/CFTR interaction.Overall, these major results grant the access to second-generation “stabilizers” potentially showing an improved biological effect in the context of cystic fibrosis
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Sattler, Maya R. "Developing Synthetic Peptide-Based Inhibitors of Human Growth Hormone Receptor." Ohio University Honors Tutorial College / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ouhonors1524838355466962.
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Heal, Jonathan Richard. "Antisense peptides as potential therapeutic agents." Thesis, Imperial College London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367576.
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Scotti, F. "Novel potential peptide therapeutics for tuberculosis therapy." Thesis, University College London (University of London), 2017. http://discovery.ucl.ac.uk/1544707/.
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Despite the existence of vaccinations, diagnostic tools and treatments, tuberculosis (TB) prevalence is increasing because of the circulation of people and misuse of antibiotics, giving rise to growing numbers of drug resistant strains of Mycobacterium tuberculosis. There is therefore a pressing need to look for new strategies against TB, in the hope of finding new drugs with novel mechanisms of anti-tubercular action or ways to potentiate the activity of already existing drugs and reduce treatment duration. This thesis explores the employment of peptides in anti-tuberculosis therapy. The project was initiated by the identification of a novel therapeutic target in M. tuberculosis: murein peptide ligase (Mpl, Rv3712), an enzyme involved in the bacterial peptidoglycan recycling process. The aim is to synthesise its putative natural substrates (peptidoglycan peptide fragments) to characterise its activity and synthesise sequence analogues. These analogues were tested on the whole-cell and will be evaluated for inhibitory activity on the recombinant Mpl enzyme and eventually could be used in combination with existing or new drugs to see whether they increase anti-tubercular potency and thus combat resistance. Attainment of the putative substrate required the synthesis of mDAP, an unusual amino acid unique to peptidoglycan. Its synthesis was successfully completed and it was incorporated in the tripeptide Mpl putative substrate. Solid-phase synthesis has been used successfully and proved effective for rapid synthesis of multiple short peptide analogues in parallel. In addition it was used to synthesise anti-tuberculosis lasso peptides, lariatins A and B, lassomycin and analogues, to evaluate the structural requirements for biological activity. The method for the heterologous expression and purification of recombinant Mpl from M. tuberculosis has been confirmed as successful, and the enzyme is available for future target-based evaluation using the synthesised mDAP-containing tripeptide and eventually for other mDAP-containing PG fragments and analogues.