To see the other types of publications on this topic, follow the link: Laboratory role.
Dissertations / Theses on the topic 'Laboratory role'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Laboratory role.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Pritchett, Duncan N. P. "Planning procedures and leadership role of the principal in professional development schools." Virtual Press, 1999. http://liblink.bsu.edu/uhtbin/catkey/1159151.
Full textAbstract:
This study was designed to determine (a) the nature and extent of planning and programmatic changes that occurred in Indiana schools that have incorporated the Ball State University (BSU) Professional Development School (PDS) model; (b) how the implementation of these changes had impacted the school principal's roles and responsibilities; (c) whether the principal serving as site coordinator effected the school or principal's work; and (d) whether geographic classification effected process or outcomes. Interviews were conducted with the principal, site coordinators and teachers during March 1999. Findings:1.The principals, teachers, and university faculty were continuously involved in planning.2.Although the duration of planning varied, all schools used planning committees, research and multiple planning processes.3.The most notable changes were instructional modifications and collaborative teaching.4.Half of the principals (two urban and one suburban) became more facilitative and more inclined to use shared decision making.5.Half of the schools had a change in the principalship during planning; one school had four different principals during this period.6.Site coordinators had a positive influence on shared decision making.7.More change occurred in the urban schools. Conclusions:1. Ongoing communication and shared decision making helped diminish possible negative consequences of principal turnover during planning.2.Differences in planning duration and frequency did not appear to affect outcomes.3.Transition to a PDS had more effects on the urban schools, suggesting that climates and cultures in suburban schools were initially more congruous with the PDS philosophy.4.The philosophy of the PDS requires a collaborative leadership style on the part of the principal. Those unwilling to assume this role are likely to withdraw from the principalship. Having the principal not serve as the site coordinator promotes collaboration and shared authority.5.Suburban educators were inclined to view PDS issues politically, while the urban educators were inclined to view them economically.Recommendations:1. The leadership style of a principal should be a primary consideration in selecting possible PDS sites.2.Longitudinal studies of PDSs should be conducted in the areas of student academic growth, curriculum, and faculty satisfaction.<br>Department of Educational Leadership
2
Jones, Shelby-Sara Ann. "The role of Lymphoblastic leukemia 1 (Lyl1) in Mycobacterium tuberculosis (Mtb) infection." Doctoral thesis, Faculty of Health Sciences, 2021. http://hdl.handle.net/11427/33727.
Full textAbstract:
Lymphoblastic leukemia 1 (Lyl1) is a well-studied transcription factor known to exhibit oncogenic potential during various forms of leukemia. Since its discovery in 1989, many reports have been published describing its relationship with cancer as well as demonstrating its function during hematopoiesis. Lyl1 has been shown to serve a significant role during thymopoiesis by contributing to T-cell development. However, it has been recently reported that irrespective of its significance during T-cell development, mature comparable single positive T-cells are observed in mouse models. The use of murine models has been crucial in identifying potential targets for host-directed therapies (HDT) which has been shown to provide great potential in treating tuberculosis (TB). It is evident that Mycobacterium tuberculosis (Mtb), the causative agent for TB, is capable of developing resistance to various treatments that target the bacterium itself. Therefore, by designing therapies that directly target host factors could assist in circumventing Mtb resistance. By analyzing Mtb-infected bone marrow-derived macrophages (BMDM) that have been subjected to genome-wide transcriptional deep sequencing of total RNA using a single molecule sequencer in conjunction with the cap analysis gene expression (CAGE) technique, various differentially expressed genes were identified, including the oncogenic transcription factor, Lyl1. With the use of murine models, we investigated whether Lyl1 is important for various immunological responses at steady state, the regulation of Lyl1 in response to various immune stimulants including LPS and whether this transcription factor is relevant in bacterial infections including Listeria monocytogenes (Lm) and Mtb. The data in this thesis demonstrate comparable immunological responses, including cellular recruitment by means of flow cytometry and cytokine responses by means of ELISA, between naïve littermate control and Lyl1-deficient mice. Further evaluation of Lyl1 regulation revealed the influence of MAPk and NFκB signaling on Lyl1 expression upon LPS stimulation by significantly downregulating this transcription factor in immune stimulated macrophages. A role for Lyl1 during bacterial infections was observed in Lm-infected mice whereby Lyl1-/- mice succumbed earlier to listeriosis compared to the littermate controls. We further established a functional role for this transcription factor during Mtb infection in vitro and in vivo. The early surrender of Lyl1-deficient mice to Mtb HN878 infection, accompanied by increased bacterial burden during chronic Mtb infection, demonstrated enhanced susceptibility in the absence of Lyl1. We show that Lyl1-deficient host susceptibility is a consequence of enhanced inflammatory responses and increased bacterial growth. This is demonstrated by increased neutrophilic inflammation, pro-inflammatory cytokine and chemokine secretion along with a reduction in anti-inflammatory cytokine release during chronic Mtb infection. Here, we demonstrate the first non-leukemia role for Lyl1 by suggesting a role and requirement for this transcription factor during bacterial infections. Given the significant role during Mtb infection, our studies suggest the use of Lyl1 associated pathways as a potential HDT target for TB.
3
Valli, Alice <1991>. "Daily torpor in laboratory mice: physiological phenotyping and role of orexins." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amsdottorato.unibo.it/8806/1/TESI%20VALLI-ALICE.pdf.
Full textAbstract:
Spontaneous torpor is a physiological phenomenon used in extreme circumstances to save energy. The physiological mechanisms ruling the torpor bouts are still unknown. Orexins (ORXs) are neuropeptides involved in the control of food behavior, in thermoregulation and sleep-wake cycle regulation this suggests that ORXs could have a role in torpor regulation.
The aims of this study were to elucidate: 1) the role of ORXs in the entrance and/or exiting from torpor; 2) the level of glycemia at the onset of torpor differs from both glucose during arousal from torpor and from baseline conditions.
In order to evaluate the role of orexins, 8 KO-ORX and 8 WT mice, were implanted with a telemetric blood pressure transducer (Data Sciences International, DSI), two cranial electrodes for the discrimination of the wake-sleep state and a thermistor in the brain cortex.
For the study of changes in glycemia related to torpor, 6 WT mice were implanted intraperitoneally with glucose telemeter (DSI). To induce torpor, mice were calorically restricted and exposed to an ambient temperature of 20°C.
The lack of ORXs does not cause significative differences in the physiological parameters during the different torpor phases. During deep torpor, in both the experimental groups, electroencephalogram (EEG) trace is similar to that described during active wakefulness while electromyogram (EMG) is almost flat, similarly to NREM sleep. This unusual sleep tracings can be observed when the minimum Tb is recorded.
We found a strong positive and linear correlation between circulating glucose and Tb during ad libitum feeding at thermoneutrality. Low blood glucose itself was not predictive of a bout of torpor, the onset of torpor was associated with the combination of low blood glucose and hyperactivity
Torpor can be considered a multifactorial and complex mechanism involving both metabolism and central nervous system control.
4
Basich, Dinko. "The role of IL-4Rá in Nippostrongylus brasiliensis-induced chronic lung pathology." Master's thesis, University of Cape Town, 2010. http://hdl.handle.net/11427/13437.
Full textAbstract:
Includes bibliographical references (leaves 108-126).<br>Infection by the parasitic nematode Nippostrongylus brasiliensis involves migration through the lungs, causing significant damage and generating chronic lung pathology. The resolution of N. brasiliensis infection and also the induction of pulmonary pathology, including goblet cell hyperplasia and acute airway inflammation, depend on IL-4Rá signalling. A key feature of IL-4Rá signalling is the induction of a strong TH2 response which induces the development of alternatively activated macrophages (AAMs). AAMs are associated with tissue remodelling and the control of exacerbated inflammation. In order to investigate potential roles for IL-4Rá in N. brasiliensis' induced lung pathology, we infected mice deficient for IL-4Rá on macrophages and neutrophils (LysMCreIL-4Rá-/lox), IL-4Rá -/- and control mice (IL-4Rá-/lox) with N. brasiliensis and examined lung pathology at days 5, 42 and 180 post infection (p.i.).All three mice strains showed similar emphysemic-like pathology (alveolar dilatation) and airway hyperresponsiveness (AHR) which was well developed by day 42 p.i. and remained chronic. However, LysMCreIL-4Rá-/lox mice consistently demonstrated earlier and increased pulmonary inflammation when compared to IL-4Rá-/lox control mice and IL-4Rá-/- mice. Immunological studies at day 5 p.i. revealed that there were increased CD4+ and CD8+ T-cell numbers and increased CD4+ IL-4 and IL-13 production in the lungs of LysMCreIL-4Rá-/lox mice when compared to control and IL- 4Rá-/- mice. LysMCreIL-4Rá-/lox mice also showed decreased pulmonary arginase activity, indicative of a reduction of AAMs. RNA transcript analysis of isolated alveolar macrophages showed a strong association with promoting inflammation in LysMCreIL-4Rá-/lox mice. Together these data demonstrate that IL-4Rá-responsive macrophages control pulmonary inflammation and play an important protective role in the lung following N. brasiliensis infection.
5
Thuecks, Derek Jon. "Laboratory investigations of dispersive Alfvén waves and their role in electron acceleration." Diss., University of Iowa, 2009. https://ir.uiowa.edu/etd/268.
Full textAbstract:
Two sets of related experiments are presented here. In the first, measurements of shear Alfvén waves are used to test the predictions of a variety of different electron collision operators, including several Krook collision operators as well as a Lorentz collision operator. New expressions for the collisional warm-plasma dielectric tensor resulting from the use of the fully-magnetized collisional Boltzmann equation are presented here. Theoretical predictions for the parallel phase velocity and damping as a function of perpendicular wave number k⊥ are derived from the dielectric tensor. Laboratory measurements of the parallel phase velocity and damping of shear Alfvén waves were made to test these theoretical predictions in both the kinetic (vte ≫ vA) and inertial (vte ≪ vA) parameter regimes and at several wave frequencies (ω < ωci). Results show that in the inertial regime, the best match between measurements and theory occur when any of the Krook operators are used to describe electron collisions. In contrast, the best agreement in the kinetic regime is found when collisions are completely ignored.
In the second set of experiments, whistler waves were launched and received by a pair of dipole antennas immersed in the plasma at two positions along the background magnetic field. According to cold-plasma theory, there is absorbtion of the whistler wave when ω = |ωce| = eB/me due to resonance with the electrons. The whistler frequency was swept from somewhat below up to the electron cyclotron frequency |ωce|. As the frequency was swept, the wave was resonantly absorbed by those parts of electron phase space density which were Doppler shifted into resonance. The transmission of the wave through the plasma was measured. This measurement of transmission can be converted into a measure of the parallel electron distribution function. This diagnostic is designed to attempt to measure modifications to the parallel electron distribution function due to interactions with inertial Alfvén waves.
6
Kampira, Elizabeth. "Pharmacogenetics of stavundine : role of genetic variation in mitochondrial DNA and polymerase gamma among adult Malawian HIV/AIDS patients." Doctoral thesis, University of Cape Town, 2013. http://hdl.handle.net/11427/3168.
Full textAbstract:
Includes abstract.<br>Includes bibliographical references.<br>Infectious diseases are endemic in Africa, especially tuberculosis (TB), malaria and human immunodefiency virus (HIV)/acquired immunodeficiency syndrome (AIDS). Genomics research has the potential to improve the health of Africans through identification of genetic markers associated with either disease susceptibility or therapeutic drug response. This project was set to investigate the genetic correlates for drugs associated with mitochondrial toxicity that are used as part of HIV therapy, especially nucleoside reverse transcriptase inhibitors (NRTIs). Toxicity from NRTIs manifests through metabolic diseases such as peripheral neuropathy, lipodystrophy, lactic acidosis and hyperlactatemia but show interpatient variability. Studying African populations is likely to open the door for the population to benefit from novel diagnostic tools and drugs developed on the basis of pharmacogenomics knowledge. In an effort to contribute to this knowledge, the role of variation in mitochondrial DNA (mtDNA) and polymerase gamma (POL-γ) on how patients respond to stavudine-containing antiretroviral therapy (ART) among adult Malawian HIV/AIDS patients was investigated.
7
Brombacher, Tiroyaone M. H. "The role of interleukin-4 receptor alpha on smooth muscle cells during helminth infection." Doctoral thesis, University of Cape Town, 2011. http://hdl.handle.net/11427/12245.
Full textAbstract:
Includes abstract.<br>Includes bibliographical references (leaves 101-111).<br>Interleukin-4 receptor alpha (IL-4Ra) signaling, mediated by the ligands IL-4 and IL- 13, is important for effective host protection during murine Nippostrongylus brasiliensis (N. brasiliensis) and Schistosoma mansoni (S. manson!) infection. Among other cell types, IL-4Ra responsive smooth muscle cells influence immunological responses and are needed for host protection during N. brasiliensis and S. mansoni infection.
8
Ndlovu, H. Hlumani. "Investigating the role of CD28 costimulation and IL-4/IL-13 responsive myeloid and lymphoid cells during helminth infections in mice." Doctoral thesis, University of Cape Town, 2013. http://hdl.handle.net/11427/3176.
Full textAbstract:
Includes abstract.<br>Includes bibliographical references.<br>The aim of this study was to evaluate the importance of CD28 in initiating protective Th2 immunity against both primary and secondary infections with N. brasiliensis. Our findings demonstrate that CD28 is required for initiation of protective Th2 immunity against primary infection with N. brasiliensis. Furthermore, the absence of CD28 impairs development of memory CD4⁺ T cell responses resulting in failure to clear adult N. brasiliensis worms during secondary infection. Failure to resolve infection was associated with reduced production of Th2 cytokines particularly IL-13 and IL-4, abrogated humoral immunity and failure to expand CXCR5⁺ TFH cells.
9
Zimmer, Matthew R. "The Role of Laboratory Services in Schizophrenic Primary Care Delivery| A Qualitative Study." Thesis, Capella University, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10684889.
Full textAbstract:
<p> The lack of primary care coordination for people with schizophrenia across the continuum of care in a rural Midwest state compromises long-term treatment success. For the purpose of primary care coordination this qualitative study explored perceptions of health care professionals that care for people with schizophrenia regarding expansion of laboratory and/or pharmacy services in the home health care setting. Mental health providers, home health care nurses, pharmacy and laboratory personnel participated in a focus group to identify common themes regarding access to care, care coordination and the utilization of laboratory and/or pharmacy services. A semistructured, open-ended focus group was used to examine the actual experiences of health care practitioners and professionals working with people with schizophrenia in the rural home health care setting. The findings of the focus group demonstrated several common themes. The first theme identified was people with schizophrenia have stigmas about their illness leading to non-compliance and reduced access to care. A second theme identified was the lack of community resources to care for people with schizophrenia. A third theme was the limited knowledge of health care providers to the utilization of home health care in the treatment of people with schizophrenia. The fourth theme was the lack of care coordination, social work and knowledge of the local issues faced by people with schizophrenia. The fifth and final theme was the lack of coordination with laboratory and pharmacy health care specialties. The results of the study may lend interest to more research regarding the utility of expanded home health care services in the care of people with schizophrenia.</p><p>
10
Jamieson, Elizabeth Clare. "The Role of Vorticity, Turbulence and Three-dimensional Flow Structure on the Development of Scour." Thèse, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/20208.
Full textAbstract:
Fundamental to the understanding of how rivers transform and shape our environment is the role of turbulence and complex, three-dimensional flow, such as vorticity, in sediment transport and erosion. However, classical sediment transport models (or formulae) are based, for the most part, on boundary shear stress and do not incorporate these natural phenomena. This is understandable given that the relationship between turbulence generation, intensity and form; the influence of turbulence on mobile sediment; and the magnitude and patterns of deposition and erosion are complex and difficult to quantify. Nevertheless, the failure to incorporate turbulence and complex, three-dimensional flow into existing models means that our understanding of sediment transport remains incomplete.
The central hypothesis of this thesis is that vortical motion is the main factor in the development of local scour. To examine this, a comprehensive experimental approach was taken. This approach involved detailed measurements of the unique three-dimensional patterns of velocity, turbulence and bed morphology associated with flow in an open channel with and without the presence of submerged groyne-like structures (stream barbs and wing dikes) at both the laboratory and field scales. Using densely spaced velocity data and new techniques for processing and analyzing these data, it was possible to identify complex features of the flow field at both scales, such as the presence of vortex cores, and correlate these with changes in bed levels. These data provide a unique perspective of the spatial variability of velocity, turbulence and bed morphology in open channels (and in particular in channel bends, where flow is highly three-dimensional). In particular, it was found that, of the flow parameters analyzed, turbulent stresses were most correlated to scour in channel bends without the presence of structures. In contrast, vorticity was found to be the dominant factor in local scour hole development in the vicinity of submerged structures at both the laboratory and field scale. Such data are rare (if non-existent) in existing experimental research, particularly at the scale of a large natural river.
This research also examines stream barb design and performance. Stream barbs (also known as submerged groynes or spur dikes) are a relatively novel approach to stream bank protection and are not common in Canada. The design and installation of stream barbs in a creek in Ottawa (Sawmill Creek) was undertaken to serve as a demonstration project for the use of these structures in a semi-alluvial channel, for which no such case studies exist. Three years of monitoring the site and the performance of these structures to reduce bank erosion and improve aquatic habitat have been carried out. Laboratory testing of stream barb performance was also undertaken and showed that with improper design, the outer bank in a channel bend may be more susceptible to erosion due to excessive local scour downstream of the barb. In particular, to avoid bank erosion downstream of the barb, barbs should be small, such that they create minimum flow obstruction, and include a bank key that is wider than the barb itself and extends in the downstream direction.
11
BORTOLUZZI, Alessandra. "PHARMACOLOGICAL ROLE OF A2A ADENOSINE RECEPTORS IN SYSTEMIC LUPUS ERYTHEMATOSUS, CLINICAL AND LABORATORY CORRELATIONS." Doctoral thesis, Università degli studi di Ferrara, 2016. http://hdl.handle.net/11392/2403041.
Full textAbstract:
Il Lupus Eritematoso Sistemico (LES) è il prototipo dei disordini autoimmuni sistemici caratterizzato da un ampio di presentazioni cliniche a carico di organi e tessuti. La rottura irreversibile dei meccanismi implicati nella risposta immunologica si manifesta con risposte autoimmuni nei confronti di antigeni nucleari endogeni e con la formazione di autoanticorpi e immunocomplessi (IC). Il LES è stato classicamente considerato una malattia autoimmune in cui il sistema immunitario adattativo gioca un ruolo predominante attraverso le cellule T e B fortemente implicate nel processo patogenetico. Durante la fase infiammatoria precoce le cellule dendritiche (CD) sono in grado di interiorizzare acidi nucleici contenenti complessi immunitari che raggiungono gli endosomi e stimolano il recettore Toll-like (TLR) 7 o 9 alla trascrizione genica di interferon (IFN)-α. IFN-α contribuisce alla maturazione delle CD mieloidi che possono attivare le cellule T autoreattive attraverso la presentazione dell'antigene e la costimolazione. Questo favorisce lo sviluppo di cellule T helper responsabili della produzione di citochine proinfiammatorie e stimola la maturazione e la differenziazione delle cellule B, la produzione di anticorpi, e la formazione di IC. Nel LES, inoltre, i monociti secernenti IC e IFN-α modulano attivamente la funzione di interleuchina (IL)-10. Nella malattia, peraltro, la capacità di IL-10 di sopprimere la produzione di citochine infiammatorie come fattore di necrosi tumorale (TNF)-α e interleuchina IL-6 è ridotta. Sempre maggiori evidenze sottolineano come l'adenosina svolga un ruolo attivo di regolazione locale di infiammazione in diverse patologie. L'adenosina è un nucleoside onnipresente coinvolto in varie funzioni fisiologiche e patologiche, attraverso lo stimolo dei recettori dell’adenosina (RA) A1, A2A, A2B, e A3 accoppiati a proteine G. Il ruolo dei RA è ben noto in condizioni fisiologiche e in una varietà di patologie, compresa l’infiammazione, le malattie neurodegenerative e il cancro. In particolare, la stimolazione A2AAR media l’inibizione di TNF-α, IL-1β, IL-2, IL-6, IFN-α e aumenta la produzione della citochina antinfiammatoria IL-10. Da questo background è maturato l’obiettivo dello studio di verificare l'ipotesi che un’alterazione dei recettori A1, A2A, A2B, e A3 dell'adenosina nei linfociti di pazienti con LES possa essere implicata nella patogenesi della malattia e di esaminare le correlazioni tra lo stato recettoriale ed i parametri clinici dei pazienti lupici. Metodi: I RA sono stati analizzati mediante saggi di saturazione di legame, analisi dell’mRNA e Western blotting nei linfociti di pazienti con LES, seguiti regolarmente presso
la nostra clinica dedicata al Lupus e accuratamente caratterizzati, e confrontati con soggetti sani. E’ stato inoltre testato l'effetto dell’agonista A2AARs sulla via regolata dal fattore nucleare kB (NF-kB) e sul rilascio di IFN-α, sul TNF-α, interleuchina IL-2, IL-6, IL-1β e IL-10. Risultati: nei linfociti ottenuti da 80 pazienti affetti da LES i recettori RAA2A sono risultati up-regolate se confrontati con 80 controlli sani appaiati per sesso ed età, mentre A1, A2B e A3 sono rimasti invariati. La densità de RAA2A è risultata inversamente correlata con l'attività della malattia misurata attraverso lo SLEDAI index-2000 (SLE disease activity index-2000), l'attività della malattia valutata nel tempo secondo precisi modelli di decorso clinico, sierosite, ipocomplementemia e presenza di anti-dsDNA. L’attivazione dei RAA2A ha inibito la via regolata dall’NF-kB e il rilascio di citochine infiammatorie (IFN-alfa, TNFalfa, IL-2, IL-6, IL-1β), mentre ha potenziato il rilascio della citochina anti-infiammatoria IL10. Conclusione: Questi dati suggeriscono il coinvolgimento dei RAA2A nella complessa rete patogenetica del LES, agendo come un sistema di modulazione del processo infiammatorio. Questo potrebbe rappresentare un percorso di compensazione per contrastare meglio l'attività della malattia. Infatti, l'attivazione dei RAA2A riduce significativamente il rilascio di citochine pro-infiammatorie e amplifica quelle con attività anti-infiammatoria suggerendo un potenziale uso traslazionale di agonisti RAA2A nel trattamento farmacologico del LES.<br>Systemic lupus erythematosus (SLE) is the prototypic multisystem autoimmune disorder with a broad spectrum of clinical presentations encompassing almost all organs and tissues. The irreversible break in immunological tolerance is manifested by immune responses against endogenous nuclear antigens and the subsequent formation of autoantibodies and immune complexes. SLE has classically been considered an autoimmune disease with a predominant adaptive immune system component, since T and B cells have been considered the most important pathogenetic players. During the early inflammatory phase plasmacytoid dendritic cells (pDCs) are able to internalize nucleic acids containing interferogenic immune complexes (ICs) that reach the endosomes and stimulate Toll-like receptors (TLR) 7 or 9, leading to interferon (IFN)-α gene transcription. IFN-α contributes to the maturation of myeloid DCs that can activate autoreactive T cells through antigen presentation and costimulation. This favours the development of T helper 1 cells responsible for high-level production of proinflammatory cytokines and enhance B cell maturation and differentiation, antibody production, and immune complex formation. In SLE the IC and IFN-α secreting monocytes modulate interleukin (IL)-10 function. The capability of IL-10 to suppress production of inflammatory cytokines such as tumour necrosis factor (TNF)-α and IL-6, implicated in promoting autoimmunity and tissue inflammation in SLE, is attenuated. Growing evidence emphasizes that the purine nucleoside adenosine plays an active role as a local regulator of inflammation in different pathologies. Adenosine is an ubiquitous nucleoside involved in various physiological and pathological functions by stimulating the G protein-coupled A1, A2A, A2B and A3 adenosine receptors (ARs). The role of ARs is well known in physiological conditions and in a variety of pathologies including inflammatory damage, neurodegenerative disorders and cancer. In particular, A2AAR stimulation mediates inhibition of TNF-α, IL-1β, IL-2, IL-6, IFN-α and increases the production of the anti-inflammatory cytokine IL-10. Objective: To test the hypothesis that dysregulation of A1, A2A, A2B, and A3 adenosine receptors (ARs) in lymphocytes from patients with Systemic Lupus Erythematosus (SLE) may be involved in the pathogenesis of the disease and to examine the correlations between the status of the ARs and the clinical parameters of SLE patients. Methods: ARs were analysed by saturation binding assays, mRNA and Western blotting analysis in lymphocytes from SLE patients regularly attending the Lupus clinic and
faithfully characterized and compared with healthy subjects. The effect of A2AAR agonist in nuclear factor kB (NF-kB) pathway and on the release of IFN-α, TNF-α, IL-2, IL-6, IL-1β and IL-10 were tested. Results: In lymphocytes obtained from 80 SLE patients A2AARs were up-regulated if compared with 80 age-matched healthy controls while A1, A2B and A3 ARs were unchanged. A2AAR density was inversely correlated with SLE disease activity index-2000, disease activity over time evaluated accordingly to the course patterns, serositis, hypocomplementemia and anti-dsDNA positivity. A2AAR activation inhibited the NF-kB activation pathway, diminished inflammatory cytokines (IFN-α, TNF-α, IL-2, IL-6, IL-1β) but potentiated the release of anti-inflammatory IL-10. Conclusion: These data suggest the involvement of A2AARs in the complex pathogenetic network of SLE, acting as a modulatory system of the inflammatory process. It could represent a compensatory pathway to better counteract the disease activity. The A2AAR activation significantly reduces the release of pro-inflammatory cytokines while enhancing those with anti-inflammatory activity suggesting a potential translational use of A2AAR agonists in SLE pharmacological treatment.
12
Liu, Ke. "Role of second messengers in controlling growth patterns of corneal epithelial cells /." View thesis, 2002. http://library.uws.edu.au/adt-NUWS/public/adt-NUWS20030718.102224/index.html.
Full textAbstract:
Thesis (Ph. D.)--University of Western Sydney, 2002.<br>"This thesis is submitted in fulfilment of the requirements of the degree of Doctor of Philosophy to the University of Western Sydney School of Biological Sciences."t.p. Includes bibliographical references (leaves 138-150).
13
Kowalczyk, Agnieszka. "Role of microbial adaptation in the biodegradation of chemical pollutants : extrapolation from laboratory to rivers." Thesis, University of Warwick, 2013. http://wrap.warwick.ac.uk/58442/.
Full textAbstract:
The Organisation for Economic Cooperation and Development (OECD) established standardized tests to predict the chemical behaviour in the environment. Difficulties exist in the extrapolation of data from laboratory OECD tests into the environment, and prediction of possible scenarios regarding environmental pollution is not accurate. The current project aimed to increase the realism of OECD tests and to investigate the microbial populations involved in the biodegradation of paranitrophenol (PNP). River water, sediment and biofilms were sampled from a stretch of River Dene with an effluent discharge point (Wellesbourne WWTP), and were used as microbial inocula in biodegradation studies. The effect of light, PNP concentration and inoculum preparation on PNP biodegradation was determined. Culture dependent techniques were used for isolation of PNP-degrading bacteria while culture independent techniques; including 16S rRNA Terminal Restriction Fragment Length Polymorphism, QPCR, and high throughput sequencing targeting the PNP functional genes (pnpA and mar), enabled detection and characterization of PNP-degrading bacteria. Light incubation lead to increased river water pH which inhibited PNP degradation. A threshold PNP concentration was determined around 42 μg/L. Application of biofilm inocula improved the reproducibility of PNP biodegradation at a concentration of 2 mg/L, and increased the amount of microbial biomass in test systems. Pseudomonas syringae was identified as a key PNPdegrader. Additional groups of PNP-degrading bacteria were detected based on the analysis of pnpA and mar functional markers. It was shown that location of sampling site for inoculum collection had no impact on biodegradation test outcome but variation of microbial inocula between sampling dates may affect the biodegradation of PNP. Core and satellite taxa analysis demonstrated that ‘biodegradation lottery’ is not the major process which determines the successful chemical biodegradation, and that probably microbial interactions within inoculum affect proliferation of PNPdegraders, and therefore impact on test results. This project revealed the lack of consideration of microbial inocula in the OECD biodegradation test guidelines. Further experimental work was suggested to expand current studies to different chemicals and rivers, and to develop more predictable approaches for better chemical risk management by Industry and Regulatory bodies.
14
Shilling, Matthew Eric. "The Role of Rooting Strategies on Drought Tolerance of Maize Hybrids: A Controlled, Laboratory Study." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1397224105.
Full text
15
Fuentes, Latice. "Laboratory study of responses of anuran amphibians to Roundup exposures / experimental design and role of sediment." Connect to this title online, 2008. http://etd.lib.clemson.edu/documents/1239895305/.
Full text
16
Masters, Seth Lucian. "The role of the SPRY domain in the SPRY domain containing SOCS box proteins (SSBs) /." Connect to thesis, 2005. http://eprints.unimelb.edu.au/archive/00001571.
Full textAbstract:
Thesis (Ph.D.)--University of Melbourne, The Walter and Eliza Hall Institute of Medical Research, Division of Cancer and Haematology, Dept. of Medical Biology,Faculty of Medicine,Dentistry and Health Sciences, 2006.<br>Typescript. Includes bibliographical references (leaves 192-210).
17
Dumbell, Rebecca. "The role of the hypothalamic-pituitary-growth axis in the regulation of seasonal and exercise induced weight gain in the Siberian hamster." Thesis, University of Aberdeen, 2014. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid+214824.
Full textAbstract:
The Siberian hamster (Phodopus sungorus) undergoes a suite of physiological changes in response to short day (SD) photoperiod which includes a marked reduction in body mass (up to 40%). This altered physiology can be reversed by a return to long day (LD) photoperiod and is driven by changes hypothalamic gene expression. Additionally, stimulation of weight regain occurs through spontaneous exercise when hamsters are provided with a running wheel (RW), despite intact photoperiod appropriate hypothalamic gene expression. The foundation hypothesis for this investigation was that the change in body weight in both paradigms is underpinned by an alteration of the growth hormone (GH) axis. Pasireotide, a somatostatin agonist, was utilised to inhibit GH secretion from the pituitary in both paradigms. Measurement of body mass, mass of internal organs, body composition by magnetic resonance imaging, hormonal analysis and in situ hybridization were used to determine the effect of a blockade of GH secretion by pasireotide. Pasireotide suppressed the GH axis in Siberian hamsters; with reduced circulating insulin-like growth factor-1 and altered hypothalamic gene expression of somatostatin (srif) and growth hormone – releasing hormone (ghrh) consistent with an inhibition of pituitary GH secretion. Pasireotide treatment inhibited RW and LD stimulated growth, and when administered to LD hamsters caused weight loss in a similar manner to that which occurs in SD and accompanied by testicular atrophy. In addition, pasireotide increased the incidence of torpor and increased bout length of this hypometabolic state in sedentary SD hamsters. In conclusion, evidence is provided for the hypothalamic – pituitary – growth hormone axis in the determination of photoperiod and RW induced body weight changes. Furthermore, the data show evidence for a novel muscle – brain pathway and evidence for a neuroendocrine pathway involved in torpor induction.
18
Cheung, Kwok-ho Alvin. "Genetic and pharmacological approaches to study the role of the polyol pathway enzymes in diabetic and ischemic retinopathy." Click to view the E-thesis via HKUTO, 2007. http://sunzi.lib.hku.hk/HKUTO/record/B39558617.
Full text
19
White, Kristi Elizabeth. "The Role of Nature in Physiological Recovery from Stress: A Critical Examination of Restorative Environments Theory." Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4791.
Full textAbstract:
Recently, health researchers have become interested in "eco-friendly" or "green" healthcare. One of the current trends in the green healthcare movement involves incorporating natural elements into health care settings to promote the health of patients and healthcare workers. Research based on Restorative Environments Theory (RET) provides insight into the rationale behind incorporating nature into the healthcare setting. RET posits that pleasant natural environments help promote stress recovery by increasing positive affect, decreasing negative affect, and reducing physiological arousal. However, the components of this theory have not been sufficiently tested using a controlled laboratory environment. The purpose of the present study was to provide a more rigorous test of RET than what is currently found in the literature by using a controlled laboratory- based design. Undergraduates from the University of South Florida were randomly assigned to view 1) no images, 2) neutral, non-nature images, 3) pleasant, non-nature images, or 4) pleasant, nature images during recovery from an anger recall task. Overall, the results of the present study did not demonstrate support for RET. There were no group differences in recovery time for any of the physiological variables with the exception of TPR. Those in the pleasant, non-nature condition took longest to recover. Further, there were no group differences in affect ratings with the exception of positive affect, which was higher for those in the no-image control condition. From an evidence-based practice framework, this study suggests that additional empirical support is needed before RET is used as a foundation to justify widespread adoption of nature-based interventions using media presentation to represent the natural environment.
20
Yan, Wing-yi, and 殷詠儀. "The role of Ca2+ in protection of preconditioning and ischaemia-induced injury in the rat heart." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B29690420.
Full text
21
Jarrett, Matthew A. "The Role of Executive and Motivational Laboratory Tasks in the Assessment of Externalizing and Internalizing Problems in ADHD-C and Non-ADHD-C Youth." Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/42446.
Full textAbstract:
The current study utilized laboratory tasks (Connersâ Continuous Performance Test, CPT; Behavioral Inhibition Task, BIT) to examine the relationships among motivation, executive functioning, and parent and teacher-reported attention, internalizing, and externalizing problems in a clinical sample of 132 children with or without Attention-Deficit/Hyperactivity Disorder, Combined Type (ADHD-C; 69% male, mean age = 9.88). Specificity was examined through total, unique, and interactive effects via hierarchical regression. Higher CPT scores (i.e., executive disinhibition) were related to greater externalizing problems in total and unique effect analyses, while a relationship between lower CPT scores (i.e., executive inhibition) and greater internalizing problems was found only in unique effect analyses. No significant effects were found for motivational inhibition (i.e., low BIT) or disinhibition (i.e., high BIT). ADHD-C was associated with greater attention and externalizing problems in total effect analyses, but only externalizing problems showed a significant relationship in unique effect analyses. Interactive effects were found for ADHD-C and executive functioning, as lower levels of CPT (i.e., executive inhibition) coupled with ADHD-C resulted in greater parent-reported attention problems. In addition, higher CPT scores (i.e., executive disinhibition) were associated with greater parent-reported externalizing problems in Non-ADHD-C children. Although some main effects were predicted, the interactive effects were somewhat surprising, particularly in relation to ADHD-C, executive inhibition, and parent-reported attention problems. Exploratory analyses revealed that this effect may have been due to greater internalizing problems in ADHD-C children at lower levels of CPT (i.e., executive inhibition). Results are discussed in relation to past studies and laboratory task validity.<br>Master of Science
22
Russell, Anthony William. "The role of adipose tissue in the insulin resistance of pregnancy in humans : a clinical and laboratory assessment /." St. Lucia, Qld, 2003. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe17694.pdf.
Full text
23
Harvey, Liam. "Laboratory and field investigations of the role of entomopathogenic fungi in regulating aphid populations in field brassica crops." Thesis, University of Warwick, 2018. http://wrap.warwick.ac.uk/101179/.
Full textAbstract:
Growers of field vegetable crops are under increasing pressure to reduce their reliance on synthetic chemical pesticides and increase their use of alternative pest management tools, including biological control agents. In this project, experiments have been conducted to investigate insect pathogenic fungi as control agents of the cabbage aphid on horticultural brassicas. These fungi contribute to the natural regulation of aphid populations, but they can also be mass-produced and applied to crops by growers as “biopesticides.” Field experiments were carried out over two seasons to investigate the association between the population dynamics of cabbage aphids, insect pathogenic fungi, and other natural enemies. This has been backed up by laboratory experiments on one particular fungus, Pandora neoaphidis, which causes natural epizootics in cabbage aphid populations, and which has not been studied against this pest in detail before. Research has focused in particular on developing laboratory methods for characterizing fungal virulence, and on the effect of temperature on fungal infectivity as a key environmental variable affecting Pandora outbreaks. Finally, the susceptibility of cabbage aphid to infection by commercially available fungal biopesticides has been compared against aphid susceptibility to Pandora neoaphidis.
24
Lewis, Courtney. "Genetics Laboratory Directors’ Perspectives on the Role of Genetic Counselors in Acquired Mutation Testing: Current and Expanded Opportunities." University of Cincinnati / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1396523134.
Full text
25
Dunn, Emily Justine. "How Do People Escape Rumination? Development of a Laboratory Task to Assess the Role of Negative Valenced Distraction." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1440347590.
Full text
26
Layman, Bruce Clare. "Role of Habitat Features and Chemical Cues in Substrate Selection by Blue Crab Megalopae: Evidence from Laboratory Experiments." W&M ScholarWorks, 1992. https://scholarworks.wm.edu/etd/1539617647.
Full text
27
Kutanzi, Kristy, and University of Lethbridge Faculty of Arts and Science. "The role of epigenetics in the rat mammary gland." Thesis, Lethbridge, Alta. : University of Lethbridge, Dept. of Biological Sciences, c2010, 2010. http://hdl.handle.net/10133/2492.
Full textAbstract:
Epigenetics plays an important role in carcinogenesis with heritable changes in DNA methylation and histone modifications intricately linked to the initiation, promotion, and progression of cancer. Evidence shows that a number of chemical and physical agents can induce epigenetic changes during carcinogenesis. Two such agents, estrogen and ionizing radiation, are generally recognized as being carcinogenic. Yet the epigenetic repercussions of these carcinogens remain relatively unknown. More importantly, the combined effect of these carcinogens has never been addressed in vivo from an epigenetic standpoint. Therefore, we focused on the effect of estrogen and ionizing radiation applied separately or in conjunction. We have found that the exposure to estrogen, either alone or in combination with radiation, induced pronounced morphological alterations, which was paralleled by modifications to the epigenomic landscape in the mammary gland. The results obtained from these rodent models can potentially be extrapolated to humans.<br>xiv, 190 leaves : ill. (chiefly col.) ; 29 cm
28
Wendt, Emily Rose. "The role of CCL25 and CCR9 in intestinal inflammation." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:c8413dcb-4861-4afd-ae13-5cb88935e54d.
Full textAbstract:
Leukocyte extravasation is mediated in part by tissue specific chemotactic cytokines (chemokines) and specific chemokine receptors expressed on the surface of circulating cells. C-C chemokine ligand CCL25 is expressed exclusively in the intestine and thymus and mediates chemotaxis by cells expressing receptor CCR9. This chemokine and receptor pair may be relevant in the pathogenesis of intestinal inflammation, in diseases such as Crohn’s disease (CD) and coeliac disease. In this thesis I investigated CCR9 expression in situ, in tissues affected by intestinal inflammation, and also examined the effects of CCR9 antagonist treatment in patients. In vitro I investigated CCR9 function using human peripheral blood T cells enriched for CCR9 by cell sorting or all-trans retinoic acid treatment. Using tissues collected as part of a clinical trial in CD testing CCR9 antagonist, CCX282-B, I investigated ways of measuring if treatment reduced the number of CCR9 expressing cells in the intestinal mucosa. However, in situ staining for CCR9 by immunohistochemistry was unsuccessful, and in this thesis, I explored reasons why this might be the case. Treatment with CCX282-B did however, show a tendency to reduce T cell density in the intestinal mucosa, although results were highly variable between individuals. In an examination of human CCR9 function in vitro I demonstrate for the first time that CCL25 stimulates CCR9 surface internalization. These data clarify the observation that CCR9 staining by IHC produces poor results in tissues where ligand is abundant, such as the intestine and thymus. I describe a novel technique for measuring calcium flux in two populations simultaneously by flow cytometry, which confirmed that in a heterogeneous population of cells, only CCR9 expressing cells respond to CCL25 by calcium flux. Variability in clinical trials is partly created by the use of concomitant medications, and in CD, corticosteroids are widely used. For the first time I show that glucocorticoids (GC) impair CCR9 mediated chemotaxis, calcium flux and intracellular signalling without changes to CCR9 mRNA and surface protein expression. Reduced CCR9 mediated signalling was accompanied by an enhanced expression and function of co-expressed CXCR4, demonstrating that the effects of GC were receptor-specific and not mediated by non-specific toxicity or inhibition of cell signalling. In a second study CCX282-B was tested in patients with coeliac disease, and in this trial, there was no reported concomitant use of GCs. It was confirmed that dietary gluten stimulates significant T cell recruitment to the intestinal mucosa with a pronounced accumulation of intraepithelial lymphocytes (IEL) and a rise in the frequency of FoxP3 expressing cells. Patients on CCX282-B had lower IEL counts, and an equivalent proportion of FoxP3 expressing T cells, suggesting that CCR9 blockade restricted the recruitment of effector T cell subsets. This thesis confirms that the accumulation of T cells is central to inflammation in the intestine and that modulating chemokine receptor function may affect this. Furthermore, this thesis demonstrates that the function of CCR9 is suppressed by GCs, which are widely used therapeutically and therefore could identify a novel mechanistic basis for their activity in CD.
29
Hines, Dustin J., and University of Lethbridge Faculty of Arts and Science. "The role of cues and the hippocampus in home base behaviour." Thesis, Lethbridge, Alta. : University of Lethbridge, Faculty of Arts and Science, 2004, 2004. http://hdl.handle.net/10133/646.
Full textAbstract:
The thesis examines the ability of animals to construct a home base. The home
base is a point in space where animals rear, groom, and circle and is a primary element in
organized spatial behaviour (Eilam and Golani 1989). Once animals establish a home
base, they make outward trips and stops, and after a series of trips and stops they return
again to the home base. The home base behaviour of animals acts as a platform for asking
questions about the cognitive organization of an environment. The thesis describes five
main findings. Control and hippocampectomized animals use (1) proximal and (2) distal
cues to form a home base and organize their behaviour. (3) Control and olfactory
bulbectomized animals form home bases in the dark where as hippocampectomized
animals are impaired suggesting self-movement but not olfactory cues play a role in
home base behaviour. A final set of experiments demonstrated that control and
hippocampectomized animals learn the position of (4) proximal and (5) distal cues so that
in the cue's absence, animals still form a home base at that position. The demonstration
that a central feature of exploratory behaviour, establishing a home base, is preserved in
hippocampectomized rats in relation to proximal, distal, and conditioned visual cues -
reveals that exploratory behaviour remains organized after hippocampal lesions. The
inability of hippocampectomized rats to form a virtual home base in the absence of visual
cues is discussed in relation to the idea that the hippocampus contributes to inertial
behaviour that may be dependent upon self-movement cues.<br>xv, 232 leaves : ill. ; 29 cm.
30
West, Mary A. "An evaluation of the role of an International External Quality Assessment Scheme in haematology laboratory practice from 1984 to 2000." Thesis, University of Portsmouth, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.439039.
Full text
31
Sanchez, Rudolph Joseph. "The Role of Trust, Leader-Member Exchange, and Organizational Justice in Employee Attitudes and Behaviors: A Laboratory and Field Investigation." PDXScholar, 2002. https://pdxscholar.library.pdx.edu/open_access_etds/3728.
Full textAbstract:
The study of interpersonal relationships continues to be a major focus of theory and research in a wide array of disciplines. The present research examined one of the most prevalent and significant interpersonal relationships in the workplace context—the dyadic relationship between a supervisor and a subordinate. This research examined the relationships between trust, quality of the leader-member exchange relationship (LMX; a measure of the quality of the dyadic relationship), perceived organizational justice, and several employee attitudes and behaviors that are important to individual workers and the organizations in which they work.
Data were collected in both laboratory and field settings. The laboratory setting allowed for the manipulation of organizational justice, which permitted inferences regarding the causal effects of organizational justice on the relationships between trust and LMX and the outcome variables examined. The field setting allowed for the testing of the hypothesized relationships in a “real world” environment in which external contextual factors (e.g., industry and organizational differences) were naturally controlled.
Two-hundred and twenty-three currently employed undergraduate students participated in the laboratory study. In the field study, data were collected in a Fortune 500 company from 113 subordinates and their supervisors. Results from both studies indicated that perceptions of trust in one's supervisor were strongly related to LMX. Importantly, in the field study, quality of the dyadic relationship was modeled as an emergent property of the perceptions of both subordinates and supervisors. Perceptions of LMX were related to a sense of overall fairness, which was jointly determined by procedural and distributive justice. Perceptions of overall fairness were related to job satisfaction, intention to quit, organizational commitment, in-role job performance, organizational citizenship behavior, and organizational retaliatory behaviors. Additionally, results of the laboratory study indicated that established perceptions of trust in one's supervisor and LMX were adversely affected by violations of either procedural or distributive justice. This adverse effect was greatest when both procedural and distributive justice were low. The theoretical and practical implications of the research are discussed.
32
Scofield, Stephanie. "Exogenous Ubiquitin: Role in Myocardial Inflammation and Remodeling Post- Ischemia/Reperfusion Injury." Digital Commons @ East Tennessee State University, 2017. https://dc.etsu.edu/etd/3347.
Full textAbstract:
Sympathetic stimulation occurs in the heart after injuries such as ischemia/reperfusion (I/R) and myocardial infarction and affects myocardial remodeling. Prolonged sympathetic stimulation can result in myocardial dysfunction through its effects on cardiac myocyte apoptosis and myocardial fibrosis. Ubiquitin (UB) is well known for its role of tagging old or damaged proteins for degradation via the UB-proteosome pathway. The role of exogenous UB however, is not fully understood. Previously, our lab showed that β-adrenergic receptor (β-AR) stimulation increased levels of extracellular UB in the conditioned media of adult rat ventricular myocytes and that UB inhibits β-AR-stimulated apoptosis. This study investigates the role of extracellular UB after myocardial I/R injury in terms of infarct size, function, inflammation and proteomic changes in vivo as well as the effects of extracellular UB on cardiac fibroblast function in vitro. First, we validated a method of consistently measuring real-time myocardial ischemia and reperfusion in vivo. Second, cardiac function was studied 3 days post I/R injury in the presence or absence of UB infusion. Echocardiographic analysis determined UB infusion increased cardiac function after I/R injury in terms of ejection fraction and fractional shortening. UB decreased infarct size and infiltration of inflammatory cells including neutrophils and macrophages as well as reduced activity of neutrophils. UB increased protein levels of matrix metalloproteinase (MMP)-2 and transforming growth factor-β1 and increased activity of MMP-9. Third, in adult rat primary cardiac fibroblasts, we demonstrate that extracellular UB interacts with CXCR-4. UB treatment decreased serum-mediated increases in fibroblast proliferation and enhanced the contraction of fibroblast-populated collagen gels. Thus, extracellular UB likely interacts with CXCR-4 to influence fibroblast function and proliferation. Additionally, UB influences cardiac remodeling in terms of heart function, infarct size, inflammatory response and proteomic profile.
33
Vilaythong, Thongloon. "The role of practical work in physics education in Lao PDR." Doctoral thesis, Umeå universitet, Institutionen för fysik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-42134.
Full textAbstract:
The aim of this thesis is to get a better understanding of the role of practical work in physics education in the Lao People’s Democratic Republic (Lao PDR). The Lao PDR is one of least developed countries in the world with a weak base for science, and poor market opportunities for science graduates. The rapidly expanding educational system has many problems concerning quality of the infrastructure and staff competence. A combination of qualitative and quantitative methods was used in the study in order to assure reliability of the results. Data was collected through questionnaires, interviews, video-recordings, and my own ethnographic experiences of working in the Lao educational system for more than thirty years. The study was informed and results analysed with help of curriculum perspective and Cultural-Historical Activity Theory (CHAT). The findings show that Lao physics education curriculum at all levels is dominated by very traditional forms of teaching with an almost total absence of practical. Official curricular documents have statements prescribing teachers to do practical work in high school and university courses. However, few institutions have functioning equipment and skilled teachers for organising practical activities. Therefore, the majority of Lao students come to university and even can finish university without experience of practical work in physics. This shows the gap that exists between intended and implemented curricula. The majority of the students understand the importance of having practical activities in physics. However, after being exposed to laboratory experiments in an introductory physics course, they expressed criticism about the quality of instruction and the process of the practical work organisation. The laboratory group work analysis showed that discussions were mainly focused on understanding the experimental procedures, manipulating equipment, and collecting data for the report rather than on the physics content (object of activity, in CHAT terms). Based on the research results, it is possible to suggest that a systemic approach is needed to stimulate the development of a new practical work culture in schools and universities. This approach should include training and incentives for science teachers, development of assessment strategies including practical work, maintenance structures for physics equipment, and technical support for the organisation of demonstrations and laboratory exercises.
34
Surquin, Murielle. "Role of Th2 cytokines and polymorphonuclear cells in allograft rejection in mice." Doctoral thesis, Universite Libre de Bruxelles, 2007. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210627.
Full textAbstract:
Acute allograft rejection remains a major problem in solid organ transplantation, because rejection may lead to acute or chronic loss of graft function. The failure of certain anti-rejection prophylactic treatments suggests that several unexpected pathways might be involved in the rejection process.<p>The aim of our experiments was to investigate the effector mechanisms responsible for skin graft rejection in mice. To adress this question, we took advantage of the possibility to restrict the alloimmune response to isolated allogeneic MHC class II molecules or to isolated minor transplantation antigens, combined with the possibility to study separately the response of CD4+ or CD8+ T cells in mice deficient for Th1 or Th2 cytokines or cytotoxic molecules. We used the bm12 skin graft combination (C57BL/6 H2Kbm12 grafted on C57BL/6 H2Kb) as a model of single MHC class II disparity and the b2microglobulin skin graft model (C57BL/6 b2m+/+ grafted on C57BL/6 b2m-/-) as a model of minor transplantation antigen disparity. Our goal was to engage a limited number of effectors, trying in a second time to block each rejection pathway selectively. <p>We showed that Fas/FasL-mediated CD4+ T cells cytotoxicity, eosinophil recruitment, activation and degranulation induced by Th2 derived cytokines, and CD4-derived IFN-g production are involved in the rejection of grafts bearing either a single MHC class II disparity or b2m-derived minor histocompatibilty antigens. In addition, rejection of MHC class II disparate skin grafts also includes the participation of neutrophils, in particular conditions where the occurrence of the Th2/eosinophil pathway was prevented. <p>Altogether, our data show a multiplicity and a redundancy of the effector pathways participating in allograft rejection. Among the different effectors pathways identified, including effectors from both innate and adaptive immune systems, some act synergistically, whereas others act as alternative pathways, depending of the degree of donor-recipient mismatch.<br>Doctorat en Sciences médicales<br>info:eu-repo/semantics/nonPublished
35
Holec, Victoria, and University of Lethbridge Faculty of Arts and Science. "Role of rat anterior cingulate cortex in effort- and courage-based decision making." Thesis, Lethbridge, Alta. : University of Lethbridge, [Dept. of] Neuroscience, c2013, 2013. http://hdl.handle.net/10133/3433.
Full textAbstract:
When given a choice between getting a high reward that requires climbing a high ramp or
pressing a lever multiple times, versus freely obtaining a low reward, healthy rats prefer
the former, while rats with lesions to the anterior cingulate cortex (ACC) prefer the latter.
We developed two novel effort tasks to examine if ACC mediates other types of physical
effort (weight-lifting) as well as emotional effort (courage). We replicated previous
findings on a modified version of the ramp-climbing task, showing that ACC lesions
impair these decisions. Lesions of ACC did not impair weight-lifting effort, even when
higher levels of effort were used and training on the task was eliminated. Initially,
lesions of ACC did not impair courage effort. When the task effort was subsequently
increased, rats with ACC lesions showed a failure to adapt to novelty throughout testing.
This research indicated that not all effort is mediated by ACC.<br>xii, 177 leaves : ill. ; 29 cm
36
Cheung, Kwok-ho Alvin, and 張國豪. "Genetic and pharmacological approaches to study the role of the polyolpathway enzymes in diabetic and ischemic retinopathy." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B39558617.
Full text
37
Tscharke, David C. "Transcriptional analysis of the role of CD8+ T lymphocytes in acute neural herpes simplex virus infection /." Title page, contents and abstract only, 1997. http://web4.library.adelaide.edu.au/theses/09PH/09pht877.pdf.
Full text
38
Duarte, Sara. "The role of Notch and GATA3 in postnatal and adult haematopoiesis." Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:e4f84964-b135-48a2-be01-551a4cef2b0d.
Full textAbstract:
The role of Notch in cell fate determination and lineage restriction in the bone marrow (BM) is controversial in the field. Recent studies have convincingly shown that Notch is dispensable for haematopoietic stem cell (HSC) regulation in adult haematopoiesis (Maillard et al., 2008). In contrast, Notch signaling has been proposed to be of importance in the regulation of BM megakaryocyte progenitor differentiation, based on dominant negative genetic approaches, identifying a potentially distinct role for Notch in adult BM haematopoiesis (Mercher et al., 2008). Here, I found that by selectively ablating the gene coding the transcription factor recombination signal-binding protein J kappa (RBP-Jk), to which all canonical Notch signaling converges, canonical Notch signaling does not mediate HSC maintenance, neither in steady state nor in conditions of stress. Furthermore, I propose, in contrast with previous studies (Mercher et al., 2008), that canonical Notch signaling plays no role in myeloerythropoiesis cell lineage commitment in the BM. My data also show that key Notch target genes are suppressed by RBP-Jk, as their expression is unaffected in Notch1-deficient BM progenitors, while target genes are upregulated in Rbp-Jk-deleted megakaryocyte and erythroid progenitors. This establishes for the first time in mammalian cells in vivo, that Notch target genes are kept in a suppressed state by RBP-Jk, potentially restricting T cell commitment to the thymus and not to the BM, at the expense of myeloerythropoiesis. Notch signaling and GATA3 are two master regulators in T cell commitment (Han et al., 2002; Ho et al., 2009; Pui et al., 1999; Radtke et al., 1999; Zhu et al., 2004). However, although very well established as being involved in the thymic stages of T cell restriction, there is little evidence of Notch and GATA3 being involved in the migration of a thymus settling progenitor (TSP) from the BM to the thymus or in the establishment of the earliest thymic progenitor (ETP) in the thymus. From this thesis work, I conclude that Notch signaling is essential for the emergence of ETPs in the thymus in a NOTCH1-independent manner. Moreover, I demonstrate, as supported by a very recent published study (Hosoya et al., 2009), that GATA3 is important for the development of the earliest T cell progenitor. GATA1 and GATA2 mediate haematopoietic stem cell maintenance in the BM. GATA1 is required for erythropoiesis, megakaryocytes and eosinophils while GATA2 is important for the proliferation and survival of HSCs. In contrast, a role for GATA3 in the BM has never been established. By using a Gata3-conditional knockout mouse model, I demonstrate that GATA3 is dispensable for HSC maintenance in steady state and following active haematopoietic regeneration as well as for HSC self-renewal in the BM.
39
Henriques, Luísa. "The dynamics of a national system of innovation and the role of the non-profit space : Portugal as a research laboratory." Doctoral thesis, École Nationale Supérieure des Mines ; Instituto Superior de Economia e Gestão, 2006. http://hdl.handle.net/10400.5/4653.
Full text
40
Szeremeta, Elise Maree. "Examining the Role of Attentional Bias in the Context of Negative and Positive Content in Real-World and Laboratory- Based Settings." Thesis, Curtin University, 2022. http://hdl.handle.net/20.500.11937/89132.
Full textAbstract:
This thesis investigates patterns of biased attention in the context of both negative and positive information, and related effects on emotional and behavioural processes. These processes were examined in the context of contamination fear and mitigation behaviour related to the COVID-19 pandemic, and also the neural underpinnings of attention and emotion using non-invasive neurostimulation of the prefrontal cortex.
41
Green, Angela Lisa. "Role of the haematopoietic transcription factor SCL in mesoderm development." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:dd7a6c6a-0a84-408b-96ad-8e4922f5ca80.
Full textAbstract:
During embryonic development, precursor cells commit to specific cell fates in response to environmental cues through the establishment of lineage-specific gene expression programmes. Transcription factors are important downstream effectors of signalling pathways that initiate and maintain cell fate decisions. The haematopoietic transcription factor SCL (TAL-1) is an essential regulator of embryonic blood development. However, the exact stage at which SCL is required, its mechanisms of action, and its genomic targets are poorly understood. Characterising, jiow SCL functions - , during haematopoietic development will provide insights into how stern cells are specified. Using the embryonic stem cell/embryoid body (ES/EB) system to model early mouse development, we describe a critical role for SCL in mesoderm patterning. SCL is first expressed in PDGFRa+ FLK1+ mesoderm populations which contain lateral, paraxial and cardiac precursors. Through loss- and gain-of-function studies, we show that SCL drives lateral mesoderm specification and activates the haematopoietic programme in a direct DNA-binding independent manner, while actively repressing alternative mesodermal fates, specifically cardiac development, in a DNA-binding dependent manner. At a molecular level, we have identified direct genomic targets of SCL in Flk-1 + mesoderm populations. These include haematopoietic and cardiac transcription factors, cardiac-specific structural proteins, signalling proteins and general transcriptional repressors; thereby strengthening the dual function of SCL in mesoderm patterning. Finally, we have shown that the cardiac transcription factor GATA4 acts in a reciprocal manner, specifying cardiac precursors while repressing a lateral mesoderm fate. Collectively, this implicates SCL as a critical transcriptional regulator of cell fate decisions in early mesodermal precursors, employing distinct molecular mechanisms to impose a blood programme. Moreover, and extending earlier reports, we document the existence of an antagonistic cross-talk between haematopoietic and cardiac lineages during mesoderm patterning. In conclusion, this work offers a cellular and molecular platform to begin to dissect the network of genetic interactions involved in these developmental processes.
42
Van, Vuuren Derick. "Postconditioning the isolated perfused rat heart : the role of kinases and phosphatases." Thesis, Stellenbosch : Stellenbosch University, 2008. http://hdl.handle.net/10019.1/20864.
Full textAbstract:
Thesis (MScMed)--Stellenbosch University, 2008.<br>ENGLISH ABSTRACT: It has recently been observed that the application of multiple short cycles of reperfusion and ischaemia, at the onset of reperfusion, elicits cardioprotection against injury due to prior sustained ischaemia. This phenomenon has been termed “postconditioning” (postC) and is of special interest due to its clinical applicability. Although much work has been done to delineate the mechanism of protection, there is still controversy regarding the precise algorithm of postC, the importance of the reperfusion injury salvage kinases (RISK), as well as uncertainty about the possible role of p38 MAPK and the protein phosphatases in postC cardioprotection.
The aims of this study were therefore:
I. To develop and characterise a cardioprotective postC protocol in the ex vivo rat heart, using both the retrogradely perfused and working heart models.
II. To characterise the profiles of PKB/Akt, ERK p42/p44 and p38 MAPK associated with the postC intervention.
III. To investigate the possible role of the serine/threonine protein phosphatases type 1 and type 2A (PP1 and PP2A) in the mechanism of postC.
Hearts from male Wistar rats were perfused in both the retrograde Langendorff (at a perfusion pressure of 100 cmH2O and diastolic pressure set between 1 and 10 mmHg) and working heart models (preload: 15 cmH20 and afterload: 100 cmH20). Several different postC protocols were tested for their cardioprotective effect, as analysed by infarct size (IFS; determined by triphenyltetrazolium chloride (TTC) staining) and functional recovery. Experimental parameters tested were the number of cycles (3,4 or 6), the duration of the cycles (10, 15, 20 or 30 seconds), the method of application (regional or global) and temperature during the intervention (36.5 or 37 °C). Different sustained ischaemic insults were also utilised: 35 minutes regional (RI) or 20, 25, 30 and 35 minutes global ischaemia (GI).
Hearts treated with a cardioprotective postC intervention or standard reperfusion after sustained ischaemia, were freeze-clamped at 10 and 30 minutes reperfusion in both perfusion models. Tissue samples were then analyzed using Western blotting, probing for total and phosphorylated PKB/Akt, ERK p42/p44 and p38 MAPK. The contribution of PKB/Akt and ERK p42/p44 activation to cardioprotection was also investigated by administration of inhibitors (A6730 and PD098059 respectively) in the final 5 minutes of ischaemia and the first 10 minutes of reperfusion, in the presence and absence of the postC intervention. The effect of these inhibitors were analyzed in terms of IFS and kinase profiles.
The possible role of the phosphatases in postC was investigated by observing the effect of cantharidin (a PP1 and PP2A inhibitor) treatment directly before sustained ischaemia (PreCanth) or in reperfusion (PostCanth), in the presence and absence of postC, on IFS and kinase profiles.
A postC protocol of 6x10 seconds global reperfusion / ischaemia, at 37°C, was found to give the best and most consistent reduction in infarct size in both the Langendorff (IFS in NonPostC: 47.99±3.31% vs postC: 27.81±2.49%; p<0.0001) and working heart (IFS in NonPostC: 35.81±3.67% vs postC: 17.74±2.73%, p<0.001) models. It could however only improve functional recovery in the Langendorff model (after 30 minutes GI: rate pressure product (RPP) recovery: NonPostC = 12.27±2.63% vs postC = 24.61±2.53%, p<0.05; and after 35 minutes GI: left ventricular developed pressure (LVDP) recovery: NonPostC = 28.40±7.02% vs postC = 48.49±3.14%, p<0.05). This protection was associated with increased PKB/Akt (NonPostC: 0.88±0.26 AU (arbitrary unit) vs postC: 1.65±0.06 AU; p<0.05) and ERK p42 (NonPostC: 2.03±0.2 AU vs postC: 3.13±0.19 AU; p<0.05) phosphorylation. Inhibition of PKB/Akt activation with A6730 (2.5 μM) abrogated the infarct sparing effect of postC.
Administration of cantharidin, either before of after ischaemia, in the absence of postC, conferred an infarct sparing effect (IFS in PreCanth: 15.42±1.80%, PostCanth: 21.60±2.79%; p<0.05) associated with an increase in the phosphorylation of MAPK p38 (administration before ischaemia: NonCanth: 1.52±0.26 AU vs PreCanth: 2.49±0.17 AU, p<0.05; and administration after ischaemia: NonCanth: 5.64±1.17 AU vs PostCanth: 10.69±1.29 AU, p<0.05) and ERK p42 (when administered in reperfusion; NonCanth: 2.24±0.21 AU vs PostCanth: 3.34±0.37 AU; p<0.05). Cantharidin treatment combined with the postC intervention did not elicit an additive infarct sparing effect (postC: 17.74±2.72%, PreCanth-postC: 13.30±3.46% and PostCanth-postC: 15.39±2.67%). In conclusion: a postC protocol of 6x10 seconds global ischaemia / reperfusion, at 37°C, confers the best infarct sparing effect in both the Langendorff and working rat heart models. This protection is associated with ERK p42 and PKB/Akt phosphorylation, although only PKB/Akt is necessary for cardioprotection. We could not find evidence for PP1 and PP2A involvement in postC, although inhibition of these phosphatases per se does elicit an infarct sparing effect. The latter observation suggests that phosphatase activation during ischaemia / reperfusion is potentially harmful.<br>AFRIKAANSE OPSOMMING: Dit is onlangs waargeneem dat toediening van meervoudige siklusse herperfusie / iskemie, met die aanvang van herperfusie, die hart teen iskemie / herperfusie beskadiging beskerm. Hierdie verskynsel, bekend as postkondisionering (postC), geniet tans baie aandag vanweë die kliniese toepaslikheid van die ingreep. Ten spyte van intensiewe navorsing om die betrokke meganisme van beskerming vas te stel, is daar steeds kontroversie oor die presiese algoritme van die ingreep, asook die betrokkenheid van die sogenaamde iskemie herperfusie oorlewings kinases (RISK). Daar bestaan ook onsekerheid oor die rol van die stres-kinase, p38 MAPK, asook die proteïen fosfatases in die meganisme van beskerming teen iskemiese besering.
Hierdie studie het dus drie doelstellings gehad:
I. Ontwikkeling van ‘n postC protokol wat beskerming ontlok in die rothart ex vivo, deur gebruik te maak van beide die retrograad geperfuseerde ballon model, asook die werkhart model.
II. Analiese van die profiele van die kinases PKB/Akt, ERK p42/p44 en p38 MAPK tydens herperfusie van postC en kontrole (NonPostC) harte.
III. Ondersoek na die moontlike rol van die serien / treonien proteïen fosfatases tipe 1 en tipe 2A (PP1 en PP2A) in die meganisme van postC beskerming.
Harte van manlike Wistar rotte is geperfuseer in beide die retrograad geperfuseerde ballon (d.i. die Langendorff) model (teen ‘n konstante perfusie druk van 100 cmH20 en ‘n diastoliese druk gestel tussen 1 en 10 mmHg), asook die werkhart model (teen ‘n voorbelading van 15 cmH20 en ‘n nabelading van 100 cmH20). Verskeie moontlike postC protokolle is getoets vir hul vermoë om kardiobeskerming te ontlok, in terme van funksionele herstel en infarktgrootte (IFS), soos bepaal deur trifenieltetrazolium chloried (TTC) kleuring. Die eksperimentele veranderlikes tydens die postC protokol wat ondersoek is, sluit in: die aantal siklusse (3, 4 of 6), die duur van die siklusse (10, 15, 20 of 30 sekondes), die wyse van postC toediening (streeks of globaal) en laastens die temperatuur tydens die ingreep (36.5 of 37 °C). Daar is ook gebruik gemaak van verskillende periodes iskemie: 35 minute streeks iskemie (RI), asook 20, 25, 30 en 35 minute globale iskemie (GI). Na 10 of 30 minute herperfusie is harte wat blootgestel is aan ‘n kardiobeskermende postC ingreep of gewone standaard herperfusie na iskemie, in beide perfusie modelle, gevriesklamp. Die weefsel proteïen-inhoud is verder geanaliseer deur van die Western blot tegniek gebruik te maak vir bepaling van die totale en fosforileerde vlakke van PKB/Akt, ERK p42/p44 en p38 MAPK. Die funksionele belang van PKB/Akt en ERK p42/p44 is verder ondersoek deur die effek van ‘n geskikte inhibitor (onderskeidelik A6730 en PD098059, toegedien tydens die laaste 5 minute van iskemie en die eerste 10 minute van herperfusie), in die teenwoordigheid en afwesigheid van die postC ingreep, op infarktgrootte en kinase aktiwiteit te monitor.
Die moontlike rol van proteïen fosfatases in postC is ondersoek deur die effek van cantharidin (‘n PP1 en PP2A inhibitor) op infarktgrootte en kinase profiele te ondersoek. Cantharidin is óf onmiddelik voor iskemie óf tydens herperfusie toegedien, in die aan – en afwesigheid van die postC ingreep.
Daar is bevind dat ‘n postC protokol van 6x10 sekondes globale iskemie / herperfusie, teen 37°C, die mees effektiewe en konstante verlaging in infarktgrootte teweeg gebring het in beide die ballon model (IFS in NonPostC: 47.99±3.31% vs postC: 27.81±2.49%; p<0.0001), asook die werkhart (IFS in NonPostC: 35.81±3.67% vs postC: 17.74±2.73%, p<0.001). Funksionele herstel kon egter slegs ontlok word in die ballon model (na 30 minute GI: tempo druk produk (RPP) herstel: NonPostC = 12.27±2.63% vs postC = 24.61±2.53%, p<0.05; en na 35 minute GI: linker ventrikulêre ontwikkelde druk (LVDP) herstel: NonPostC = 28.40±7.02% vs postC = 48.49±3.14%, p<0.05). Die infarkt-besparende effek van postC was geassosieer met ‘n toename in die fosforilasie van beide PKB/Akt (NonPostC: 0.88±0.26 AU (arbitrêre eenhede) vs postC: 1.65±0.06 AU; p<0.05) en ERK p42 (NonPostC: 2.03±0.2 AU vs postC: 3.13±0.19 AU; p<0.05). Inhibisie van PKB/Akt met A6730 (2.5 μM) het die infarkt-besparende effek van postC opgehef.
Inhibisie van PP1 en PP2A opsigself, deur toediening van cantharidin óf voor óf na iskemie (in die afwesigheid van postC), het ‘n infarkt-besparende effek ontlok (IFS in PreCanth: 15.42±1.80%, PostCanth: 21.60±2.79%; p<0.05). Hierdie kardiobeskerming was geassosieer met ‘n toename in die fosforilasie van beide p38 MAPK (met toediening voor iskemie: NonCanth: 1.52±0.26 AU vs PreCanth: 2.49±0.17 AU, p<0.05; en toediening na iskemie: NonCanth: 5.64±1.17 AU vs PostCanth: 10.69±1.29 AU, p<0.05), asook ERK p42, indien cantharidin toegedien is tydens herperfusie (NonCanth: 2.24±0.21 AU vs PostCanth: 3.34±0.37 AU; p<0.05). Kombinasie van cantharidin behandeling met postC toediening kon egter nie ‘n kumulatiewe infarkt-besparende effek uitlok nie (postC: 17.74±2.72%, PreCanth-postC: 13.30±3.46% en PostCanth-postC: 15.39±2.67%).
In samevatting: ‘n PostC protokol van 6x10 sekondes globale iskemie / herperfusie, teen 37°C, ontlok die mees effektiewe infarkt-besparende effek in beide die ballon, sowel as die werkhart modelle. Alhoewel hierdie beskerming geassosieer is met ‘n toename in die fosforilasie van beide PKB/Akt en ERK p42/p44 tydens herperfusie, is dit slegs PKB/Akt wat van funksionele belang is in die meganisme van kardiobeskerming. Ons kon geen bewyse vind vir die betrokkenheid van PP1 en PP2A in postC beskerming nie, alhoewel inhibisie van hierdie fosfatases opsigself infarkt-besparend is. Laasgenoemde waarneming toon dat fosfatase aktivering tydens iskemie / herperfusie skadelike gevolge mag hê.
43
Conley, Sabena. "Role of Vav2 in Podocyte Inflammasome Activation and Glomerular Injury During Hyperhomocysteinemia." VCU Scholars Compass, 2016. http://scholarscompass.vcu.edu/etd/4628.
Full textAbstract:
Hyperhomocysteinemia (hHcys) is a widely known pathogenic factor in the progression of end-stage renal disease (ESRD) and it is also associated with an increased risk for injurious cardiovascular pathologies during ESRD. HHcys is linked to the formation and activation of the NOD-like receptor protein 3 (NLRP3) inflammasome, characterized as a critical early mechanism initiating the inflammatory response. NADPH oxidase (NOX)-derived reactive oxygen species (ROS) mediate the activation of the NLRP3 inflammasome in podocytes in response to elevated levels of homocysteine (Hcys) in vitro and in vivo. However, it remains unknown how NLRP3 inflammasome activation is triggered by NOX. The aim of the present study sought to determine the signaling cascade that triggers glomerular injury and sclerosis during hHcys mediated by Vav2, a guanine nucleotide exchange factor (GNEF). Using both genetic and pharmacological interventions of Vav2, we first tested whether this GNEF is involved in hHcys-induced NLRP3 inflammasome activation in podocytes by its role in activation of the Rac-1-NOX complex. Further, we explored whether pharmacological targeting of Vav2 activation may regulate NLRP3 inflammasome signaling pathway during hHcys-induced glomerular injury. We found that mice with hHcys (on the FF diet) or oncoVav2 (a constitutively active form of Vav2) transfection in the kidney exhibited increased colocalization of NLRP3 with apoptosis-associated speck-like protein (ASC) or caspase-1 and elevated IL-1β levels in glomeruli, indicating the formation and activation of the NLRP3 inflammasome. This glomerular NLRP3 inflammasome activation was accompanied by podocyte dysfunction and glomerular injury, even sclerosis. Local transfection of Vav2 shRNA plasmids significantly attenuated hHcys-induced NLRP3 inflammasome activation, podocyte injury, and glomerular sclerosis. In cultured podocytes, Hcys treatment and oncoVav2 transfection increased NLRP3 inflammasome formation and activation. This NLRP3 activation was inhibited by Vav2 shRNA, associated with reduction of Rac-1 activity and ROS production. Administration of NSC23766, a Rac-1 inhibitor substantially attenuated inflammasome formation, desmin expression and decreased podocin expression in glomeruli of hHcys mice. These results suggest that elevated Hcys levels activate Vav2 and thereby increase NOX activity, leading to ROS production. ROS trigger NLRP3 inflammasome activation, podocyte dysfunction and glomerular injury. Therefore, the present study defines a novel mechanism underlying hHcys-induced NLRP3 inflammasome activation and its progression to ESRD.
44
Flexas, Sbert Maria del Mar. "Mesoscale variability of the northern current in the gulf of lions and the role of bottom topography." Doctoral thesis, Universitat Politècnica de Catalunya, 2003. http://hdl.handle.net/10803/6386.
Full textAbstract:
The Northern Current flows cyclonically contouring the continental slope in the NW Mediterranean. At the entrance of the Gulf of Lions this current is about 20 -- 30 km wide and flows along the deepest half of the continental slope, i.e. over the 1000 to 2000 m isobaths approximately. Surface speeds are of 30 -- 50 cm s^{-1}. In the MATER HFF experiment (March -- May 1997) mesoscale variability of the Northern Current is observed from current meter records, SST images and hydrographic data. The HFF experimental box is 20 x 40 km, covering the upper half of the slope (i.e. covering from 250 m to 1250 m depth isobaths). Current meter and satellite data show that the site is embedded in a region of significant Northern Current meandering and eddy activity. From SST images, meander wavelengths are estimated larger than 60 km, embracing smaller structures. These flow patterns affect upper-layer waters down to at least 650 m depth. Current meter data distinguish two narrow energetic bands centred at 3.5 days and 7.5 days, respectively, in agreement with previous studies.<br/>Baroclinic instability is viewed as a possible mechanism to explain the generation of the Northern Current meanders. The analytical model of Tang (1975) predicts the development of unstable waves of wavelength (> 60 km) and periods compatible with the 7.5 day band recorded with current meter devices. The higher frequency band of 3.5 days is out of the frequency range predicted by the classical baroclinic instability theory and it is discussed as a restriction of quasi-geostrophic theory.<br/>Barotropic instability is studied using a laboratory model of a -westward' jet flowing over the lower half of the continental slope, which considers dynamic similarity with the Northern Current. The laboratory model is cross-validated with a corresponding numerical model. Jet instabilities of currents similar to the Northern Current (i.e. westward jets) occur at the edges of the jet, showing a clear meandering tendency over the mid-slope. Westward currents of Ro = 0.1 -- 0.2 develop instabilities of wavelengths (50 -- 75 km) similar to those observed from SST images, with periods (3.3 -- 3.8 days) compatible with the 3.5 days period band recorded with HFFE current meters.<br/>The laboratory and numerical experiments have reproduced westward jets (as the Northern Current), but also eastward jets, in order to have a full approach to better understand the role of the bottom topography on barotropic instabilities. The slope current instabilities are successfully explained by the Marcus and Lee theory (1998) of jets on a beta plane. This theory is valid for westward flows with Ro > 0.1 and for eastward flows with Ro > 0.2 (jets of the so-called Regime II flows in this thesis), and it states that the instabilities of each shear layer of the barotropic jet take the appearance of a Kelvin-Helmholtz-like pattern, associated with a Rossby wave (of topographic origin in our case). According to this theory, the differences between eastward and westward jets rely on the disposition of the Rossby waves --at the centre of the current in eastward flows and at the edges of the jet in westward currents. Jets over a sloping bottom with small Rossby numbers (Ro < 0.1 for westward jets; Ro < 0.2 for eastward jets) show a flow pattern (the so-called Regime I in this thesis) that has common characteristics for eastward and westward flows. In these -small'-Ro flows, Kelvin-Helmholtz-like instabilities dominate, whereas Rossby waves are too weak to produce any major difference between jets flowing in eastward or westward direction. This occurs when the topographic influence, assumed proportional to the Ro number of the jet, is small.<br/>The differences between eastward and westward slope currents observed in this work (and similar observations of jets on a beta-plane from previous works) are explained in this thesis by a simple scheme based on conservation of potential vorticity, considering there are two main components in balance: the shear-induced vorticity and the topographically induced vorticity. The signs of these two components are determined by the relative direction of the flow with respect to the inclination of the bottom topography. Once the critical Rossby number is overpassed so that the topographic effects are important (Ro > 0.1 for westward jets; Ro > 0.2 for eastward jets), conservation of potential vorticity tends to enhance vortices at the centre of eastward jets --eastward jets show meandering at the jet core. In westward jets, potential vorticity conservation is responsible of enhancing vortices at each edge of the jet. Thus, westward jets (as the Northern Current) are broad and meandering occurs at the jet edges.<br/>In Ro > 0.1 westward flows (i.e. Regime II westward jets) a topographic Rossby wave appears over the shelf break. This result is likely observed because of the specific topography used in this work --a continental slope and a continental shelf separated by a shelf break, producing a strong change in ambient potential vorticity. Numerical simulations reveal that this Rossby wave is triggered by the slope current. This topographic Rossby wave is a robust pattern, since it is independent of the position of the current over the slope, the shape of the velocity shear profile of the jet, and the jet width. Although this type of wave could not be inferred from the HFFE field data, it could be a focus of study in further field experiments. It also needs further analytical consideration.<br/> The general conclusion extracted from this thesis that tries to explain the mesoscale variability associated to the Northern Current is that both baroclinic and barotropic instability could explain part of the oceanic observations. As a consequence, mixed barotropic-baroclinic instability (which occurs at wavelengths which are between those corresponding to pure barotropic and pure baroclinic instability) is thought to play an important role on the observed mesoscale variability. The resulting wavelength would depend on the relative strength of both mechanisms.
45
Liu, Ke. "Role of second messengers in controlling growth patterns of corneal epithelial cells." Thesis, View thesis, 2002. http://handle.uws.edu.au:8081/1959.7/387.
Full textAbstract:
The purpose of this thesis was to investigate mechanisms contolling the growth of corneal epithelial cells, particularly the intracellular signals involved with stratification compared with cellular migration and maturation. Buttons of epithelium were cultured in different culture media. The explants were monitored microscopically for their growth patterns and finally fixed and examined for cytokeratin, vimentin and actin. Different growth patterns were observed in the different media, indicating that different signalling patterns must be operating in these cells depending upon the media in which they were grown. To investigate the intracellular pathways controlling the different growth patterns, the protein phosphorylation of different cultures was investigated. The two proteins, p57 and p30, are strongly suggested to be associated with stratification of the epithelial cells. The possible involvement of the common serine kinase, PKC, in controlling the growth pattern of corneal epithelial cells were also investigated. The results suggested that an intracellular pathway involving PKC promotes the maturation and spread of the cells but is not involved in their stratification. These experiments taken together indicate that the different aspects of corneal epithelia cell growth are tightly controlled and may occur quite independently. Specific protein expression appears to be important for stratification, and phosphorylation of proteins by PKC appears to be involved with the maturation of epithelial cells from basal cells. It also indicates that the mature cells are capable of producing the extracellular matrix protein fibronectin which appears to have an important role in causing the spread as distinct from the stratification of the corneal epithelial cells.
46
Bowen, Gail Ann. "The Role of the Principal in Implementing Change in the Professional Development School." Thesis, University of North Texas, 1996. https://digital.library.unt.edu/ark:/67531/metadc278893/.
Full textAbstract:
This qualitative research study investigated the role of the principal in implementing change in the professional development school (PDS). The study involved 7 elementary schools and 4 school-university collaboratives in the Texas network of 17 Centers for Professional Development and Technology (CPDTs). The research questions focused on the role, leadership, and management concerns of the PDS principal.
47
Porther, Nicole. "Intracellular Signaling and Trafficking in Cancer: Role of Rab5-GTPase in Migration and Invasion of Breast Cells." FIU Digital Commons, 2015. http://digitalcommons.fiu.edu/etd/1939.
Full textAbstract:
Metastasis is characterized pathologically by uncontrolled cell invasion, proliferation, migration and angiogenesis. Steroid hormones, such as estrogen, and growth factors, which include insulin growth factor I/II (IGF-1/IGF-2) therapy has been associated with most if not all of the features of metastasis. It has been determined that IGF-1 increases cell survival of cancer cells and potentiate the effect of E2 and other ligand growth factors on breast cancer cells. However not much information is available that comprehensively expounds on the roles of insulin growth factor receptor (IGFR) and Rab GTPases may play in breast cancer. The latter, Rab GTPases, are small signaling molecules and critical in the regulation of many cellular processes including cell migration, growth via the endocytic pathway. This research involves the role of Rab GTPases, specifically Rab5 and its guanine exchange factors (GEFs), in the promotion of cancer cell migration and invasion. Two important questions abound: Are IGFR stimulation and downstream effect involved the endocytic pathway in carcinogenesis? What role does Rab5 play in cell migration and invasion of cancer cells? The hypothesis is that growth factor signaling is dependent on Rab5 activity in mediating the aggressiveness of cancer cells. The goal is to demonstrate that IGF-1 signaling is dependent on Rab5 function in breast cancer progression. Here, the results thus far, have shown that while activation of Rab5 may mediate increased cell proliferation, migration and invasion in breast cancer cells, the Rab5 GEF, RIN1 interacts with the IGFR thereby facilitating migration and invasion activities in breast cells. Furthermore, endocytosis of the IGFR in breast cancer cells seems to be caveolin dependent as the data has shown. This taken together, the data shows that IGF-1 signaling in breast cancer cells relies on IGF-1R phosphorylation, caveolae internalization and sequestration to the early endosome RIN1 function and Rab5 activation.
48
Fricke, Claudia. "Postmating Sexual Selection and its Role in Population Divergence in Beetles." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Universitetsbiblioteket [distributör], 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-6583.
Full text
49
Dutton, Sarah. "An investigation into the relationship between laboratory measured attentional bias and real life attentional bias for alcohol-related cues and its role in alcohol behaviour." Thesis, University of Liverpool, 2015. http://livrepository.liverpool.ac.uk/2013860/.
Full textAbstract:
There is a large evidence-base suggesting the role of attentional bias in addictive behaviours. However, there has been no evidence to date of any research in the field of alcohol addiction that investigates if traditionally used laboratory-based measures of attentional bias correspond to more naturalistic methods in real-world settings. A non-clinical sample of 43 students aged 18-30 were recruited from the University of Liverpool. Participants completed two measures of attentional bias; a fixed eye tracker measure utilising the visual probe task in a standard laboratory set-up, and a head mounted eye tracker within a more naturalistic setting. Attentional bias was measured by participants fixation duration to alcohol compared with non-alcohol/neutral stimuli. Participant’s drinking habits were also measured using the Time Line Follow Back and the Alcohol Use Disorders Identification Test. A measure of craving and measures of mood were also administered. Correlation analyses were conducted on 34 complete data sets. No significant correlations were found between the two measures of attentional bias. Some significant correlations were found, however, between drinking-related variables, craving and the fixed eye tracker attentional bias measure supporting previous findings within the literature. Additional analyses were conducted to explore the relationship between mood, attentional bias measures and drinking-related variables. The results of this study are discussed in detail in relation to the theoretical and clinical implications and future research is suggested.
50
Tulsankar, Smita Sadanand. "Role of natural productivity in growth performance and health of marron (Cherax cainii, Austin 2002) reared under semi-intensive aquaculture system and controlled laboratory conditions." Thesis, Curtin University, 2021. http://hdl.handle.net/20.500.11937/86727.
Full textAbstract:
The research from commercial marron ponds and laboratory–based experiments investigated the multi-facet interactions among seasons, plankton abundance and diversity with selected dissolved trace elements and finally their impact on marron yield, health and characterization of the gut microbiome. The results showed that trace element supplementation altered the plankton density, species diversity and marron gut microbiota and finally the presence of zooplankton in the culture system reflected the enhanced marron growth and health.