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Articles de revues sur le sujet "N-MTAA"
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Hoeppner, Astrid, Frank Thomas, Alma Rueppel, Reinhard Hensel, Wulf Blankenfeldt, Peter Bayer et Annette Faust. « Structure of the corrinoid:coenzyme M methyltransferase MtaA fromMethanosarcina mazei ». Acta Crystallographica Section D Biological Crystallography 68, no 11 (18 octobre 2012) : 1549–57. http://dx.doi.org/10.1107/s090744491203853x.
Texte intégralRésumé :
The zinc-containing corrinoid:coenzyme M methyltransferase MtaA is part of the methanol–coenzyme M–methyltransferase complex ofMethanosarcina mazei. The whole complex consists of three subunits: MtaA, MtaB and MtaC. The MtaB–MtaC complex catalyses the cleavage of methanol (bound to MtaB) and the transfer of the methyl group onto the cobalt of cob(I)alamin (bound to MtaC). The MtaA–MtaC complex catalyses methyl transfer from methyl-cob(III)alamin (bound to MtaC) to coenzyme M (bound to MtaA). The crystal structure of the MtaB–MtaC complex fromM. barkerihas previously been determined. Here, the crystal structures of MtaA fromM. mazeiin a substrate-free but Zn2+-bound state and in complex with Zn2+and coenzyme M (HS-CoM) are reported at resolutions of 1.8 and 2.1 Å, respectively. A search for homologous proteins revealed that MtaA exhibits 23% sequence identity to human uroporphyrinogen III decarboxylase, which has also the highest structural similarity (r.m.s.d. of 2.03 Å for 306 aligned amino acids). The main structural feature of MtaA is a TIM-barrel-like fold, which is also found in all other zinc enzymes that catalyse thiol-group alkylation. The active site of MtaA is situated at the narrow bottom of a funnel such that the thiolate group of HS-CoM points towards the Zn2+ion. The Zn2+ion in the active site of MtaA is coordinated tetrahedrallyviaHis240, Cys242 and Cys319. In the substrate-free form the fourth ligand is Glu263. Binding of HS-CoM leads to exchange of the O-ligand of Glu263 for the S-ligand of HS-CoM with inversion of the zinc geometry. The interface between MtaA and MtaC for transfer of the methyl group from MtaC-bound methylcobalamin is most likely to be formed by the core complex of MtaB–MtaC and the N-terminal segment (a long loop containing three α-helices and a β-hairpin) of MtaA, which is not part of the TIM-barrel core structure of MtaA.
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Vivan, Rodrigo Ricci, Juliane Maria Guerreiro-Tanomaru, Roberta Bosso-Martelo, Bernardo Cesar Costa, Marco Antonio Hungaro Duarte et Mário Tanomaru-Filho. « Push-out Bond Strength of Root-end Filling Materials ». Brazilian Dental Journal 27, no 3 (juin 2016) : 332–35. http://dx.doi.org/10.1590/0103-6440201600340.
Texte intégralRésumé :
Abstract The aim of this study was to evaluate the bond strength of root-end filling materials. Forty 2-mm-thick slices were obtained from human single-rooted teeth. After root canal preparation using a 1.5 mm diameter cylindrical drill, the dentinal walls were prepared by diamond ultrasonic tip (CVD T0F-2). The specimens were divided according the material (n=10): MTA Angelus (MTAA), MTA Sealer (MTAS, experimental), Sealer 26 (S26) and zinc oxide and eugenol cement (ZOE). The push-out test was performed in a mechanical test machine (EMIC DL 2000) at 1 mm/min speed. The failure type was evaluated by stereomicroscopy. The results were subjected to ANOVA and Tukey test, at 5% significance level. MTAA (19.18 MPa), MTAS (19.13 MPa) and S26 (15.91 MPa) showed higher bond strength (p<0.05). ZOE (9.50 MPa) showed the least bond strength values (p<0.05). Adhesive failure was prevalent in all groups, except for ZOE, which showed mixed failures. It was concluded that root-end filling materials MTA Angelus, MTA Sealer and Sealer 26 showed higher bond strength to dentinal walls than zinc oxide and eugenol cement after retrograde preparation.
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Shawar, S. M., R. G. Cook, J. R. Rodgers et R. R. Rich. « Specialized functions of MHC class I molecules. I. An N-formyl peptide receptor is required for construction of the class I antigen Mta. » Journal of Experimental Medicine 171, no 3 (1 mars 1990) : 897–912. http://dx.doi.org/10.1084/jem.171.3.897.
Texte intégralRésumé :
Maternally transmitted factor (Mtf) is a mitochondrial gene that controls the antigenic polymorphism of the MHC class I maternally transmitted antigen (Mta). Synthetic peptides from the NH2 terminus of the mitochondrially encoded NADH dehydrogenase subunit 1 (ND1) mimic Mtf peptide activity in an allele-specific manner. We show that the minimal ND1-alpha peptide length recognized by Mtaa-specific polyclonal CTLs was between 8 and 12 amino acids, while some Mtaa-specific CTL clones recognized a six amino acid peptide. The N-formyl group at the NH2 terminus of ND1 was essential for Mta activity. Competition experiments using N-substituted ND1-alpha peptides showed that an N-formyl peptide receptor on the target cell, which differs from the chemotactic peptide receptor, was required for Mta expression. The specificity of this receptor can account for the distinct immune restriction of Mta in which Mtf peptides are uniquely restricted by Hmt. It is possible that the Hmt gene product is the N-formyl peptide receptor itself and that it represents a class I antigen presentation molecule specialized for binding, transport, and immune presentation of N-formyl-peptide antigens of mitochondrial and prokaryotic origin.
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Rudik, Irina S., Olesya N. Katasonova, Olga B. Mokhodoeva, Tatyana A. Maryutina, Boris Ya Spivakov et Igor V. Ilyukhin. « SEPARATION OF P t (IV), P d (II) AND R h (III) FROM CHLORIDE SOLUTIONS BY MULTISTAGE SOLVENT EXTRACTION USING NITROGEN-CONTAINING EXTRACTANTS ». Industrial laboratory. Diagnostics of materials 85, no 4 (15 mai 2019) : 5–10. http://dx.doi.org/10.26896/1028-6861-2019-85-4-5-10.
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The possibility of Pd (II), Pt (IV), and Rh (III) separation from chloride solutions by solvent extraction in rotating coiled columns (RCC) is demonstrated. The reagents most frequently used in extraction of platinum metals were selected as extractants: trioctylamine (TOA), methyltrialkylammonium chloride (MTAA), tributylphosphate (TBP), N, N, N',N'-tetra-re-octyldiglyTOlamide (TODGA). The completeness of extraction of the platinum group metals from individual and mixed hydrochloric acidic and chloride solutions was studied depending on the nature and concentration of the extractant, acidity of the test solutions and other factors. Optimal conditions for the quantitative extraction of metals from model hydrochloric acidic and chloride solutions and subsequent selective separation at the stripping stage are specified. A scheme of multistaged extraction separation of Pd (II), Pt (IV), and Rh (III) from chloride solutions using a 0.05 M solution of MTAA in toluene as a stationary phase in RCC is proposed. The scheme includes extraction of Pd (II) and Pt (IV) ions from a chloride solution (0, 1 M HCl + 30 g/liter NT) into the organic phase with simultaneous separation of Rh(III) remaining in the aqueous phase, and sequential stripping of Pd (II) and Pt (IV) from the organic phase with a 0.01 M solution of thiourea in 0.1 M HCl and a 1 M solution of thiourea in 0.5 M HCl, respectively. The scheme was tested in separation of the platinum group metals from the technological solution of a given composition. The degree of metal extraction with a 0.05 M MTAA solution in toluene and sequential stripping with thiourea solutions is 99.5% for Rh (III), 99.9% for Pd (II), and 97.4% for Pt (IV). The separated water fractions of rhodium and platinum after leaving the column did not contain impurities of other platinum metals whereas the water fraction of palladium contained 0.5% Pt.
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Dakyaga, Francis, Alphonce G. Kyessi et Joel M. Msami. « Water Access Today and Tomorrow : Domestic Water Sustainability under Informal Water Supply Markets in Dar es Salaam, Tanzania ». Journal of Sustainable Development 11, no 6 (29 novembre 2018) : 120. http://dx.doi.org/10.5539/jsd.v11n6p120.
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The article examined domestic water access sustainability under informally driven water supply market, drawing on suppliers-consumers’ perspectives. Analysis was done on the capacities of the informal water suppliers for sustainable water provision, how the informal water markets operate, and clients’ perspectives of water access today and tomorrow. Four different data set were comparatively analyzed from interviews with the Municipal Water Engineer (MWE), Ward Health Officer (WHO), 3 Mtaa leaders from 3 informal settlements, interviews with 43 informal water sellers from three informal settlements, including a survey of (n = 292) clients in three informal settlements. It was realized that though informal water suppliers are sociocultural capable of providing flexible and gender-sensitive water supply services, households have unsustainable access to improved water due to the financial, hydro-technical, institutional and organizational in capacities of the informal water sellers coupled with the low financial abilities of low-income earning households to continuously purchase water for domestic activities. It was observed that informal settlements’ dwellers are less likely to meet their water supply needs in the near future if their income status together with the financial, hydro-technical, organizational and institutional capacities of the informal water sellers are not improved.
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Kobayashi, Kazufumi, Sadahisa Ogasawara, Aya Takahashi, Yuya Seko, Hidemi Unozawa, Rui Sato, Shunji Watanabe et al. « Evolution of Survival Impact of Molecular Target Agents in Patients with Advanced Hepatocellular Carcinoma ». Liver Cancer 11, no 1 (6 décembre 2021) : 48–60. http://dx.doi.org/10.1159/000519868.
Texte intégralRésumé :
Background and Aims: The prognosis of patients with advanced hepatocellular carcinoma (HCC) is expected to improve as multiple molecular target agents (MTAs) are now available. However, the impact of the availability of sequential MTAs has not been fully verified yet. Approach and Results: We retrospectively collected the data on the whole clinical course of 877 patients who received any MTAs as first-line systemic therapy for advanced HCC between June 2009 and March 2019. The study population was divided into 3 groups according to the date of first-line MTA administration (period 1: 2009–2012, n = 267; period 2: 2013–2016, n = 352; period 3: 2017–2019, n = 258). Then, we compared the number of MTAs used, overall survival (OS), and MTA treatment duration among the 3 groups. Analysis was also performed separately for advanced-stage and nonadvanced-stage HCC. The proportion of patients who received multiple MTAs was remarkably increased over time (1.1%, 10.2%, and 42.6% in periods 1, 2, and 3, respectively, p < 0.001). The median OS times were prolonged to 10.4, 11.3, and 15.2 months in periods 1, 2, and 3, respectively (p = 0.016). Similarly, the MTA treatment durations were extended (2.7, 3.2, and 6.6 months in periods 1, 2, and 3, respectively; p < 0.001). We confirmed that the correlation between OS and MTA treatment duration was strengthened (period 1: 0.395, period 2: 0.505, and period 3: 0.667). All these trends were pronounced in the patients with advanced-stage HCC but limited in the patients with nonadvanced-stage HCC. Conclusions: The availability of multiple MTAs had steadily improved the prognosis of patients with advanced HCC patients, particularly advanced-stage HCC patients.
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Baldissera, Renata, Ricardo Rosa, Manuela Santini, Angela Nascimento, Milton Kuga, Jefferson Pereira, Francisco Montagner et Marcus Só. « CLSM assessment of tubule penetration and bacterial leakage evaluation of two resin-based sealer ». Journal of Research in Dentistry 2, no 5 (1 septembre 2014) : 388. http://dx.doi.org/10.19177/jrd.v2e52014388-397.
Texte intégralRésumé :
AIM: The aims of this study were to assess the penetration of two endodontic sealers (salicylate and epoxy resin-based sealers) into dentinal tubules using CLSM; and to evaluate the bacterial leakage of roots filled with the same sealers associated with gutta-percha. MATERIAL AND METHODS: For sealer penetrability assessment, thirty bovine roots were instrumented and divided into three groups: AHP: EDTA + filling with AH Plus and gutta-percha (n=10), MTAF: EDTA + filling with MTA Fillapex and gutta-percha (n=10), control group: canals were not irrigated with EDTA and were filled with gutta-percha and AH Plus (n=5) or MTA Fillapex (n=5). Rhodamine B was added to the sealers in order to provide adequate fluorescence. The roots were transversely sectioned 3mm from the apex to enable CLSM analysis. Leakage was evaluated for turbidity of the broth in a split chamber model system for 30 days, using Enterococcus faecalis as a microbial marker. Thirty roots were instrumented and divided in four grupos: AHP: filling with AH Plus and gutta-percha (n=10); MTAF: filling with MTA Fillapex and gutta-percha (n=10); positive control: filling with gutta-percha without sealer (n = 5); negative control: sealing with cyanoacrylate to test the seal of the system (n = 5). RESULTS: The medians for dentinal tubule penetration were 6.8% (AHP) and 6.6% (MTAF) (P = 0.82). The average time for bacterial leakage was 8 days in both experimental groups (P = 0.79). CONCLUSION: MTA Fillapex and AH Plus presented similar behavior regarding dentinal tubule penetration and bacterial leakage.
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Kobayashi, Kazufumi, Sadahisa Ogasawara, Aya Takahashi, Yuya Seko, Satoshi Tsuchiya, Kenji Iwai, Rui Sato et al. « Transition of molecular target agent therapy in advanced hepatocellular carcinoma : A multicenter, retrospective study. » Journal of Clinical Oncology 39, no 3_suppl (20 janvier 2021) : 317. http://dx.doi.org/10.1200/jco.2021.39.3_suppl.317.
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317 Background: There have been considerable advances in systemic chemotherapy for hepatocellular carcinoma (HCC) in recent times. Currently, four molecular target agents (MTA) are available for HCC treatment in Japan. Sequential therapy using multiple MTAs is being considered as the gold standard of treatment. However, the effectiveness of the treatment strategy transition for HCC remains unclear. The present study aimed to clarify the current practical use of MTAs and its effectiveness in HCC treatment. Methods: In this multicenter, retrospective study, we collected and analyzed the clinical data of 877 patients who underwent MTA therapy for HCC from June 2009 to March 2019 at several institutes in Japan. The patients were classified into 3 groups as per the period of initial MTA treatment beginning (period 1: 2009–2012, n = 267; period 2: 2013–2016, n = 352; period 3: 2017–2019, n = 258). These 3 periods were defined to have approximately same term. Period 3 means the era of multiple MTAs because of the approval of regorafenib in Japan in 2017. We assessed the patient characteristics, MTA use, and prognosis of the 3 groups. Results: The proportion of patients with advanced-stage HCC, defined according to the Barcelona Clinic Liver Cancer staging system, in each period was 70.1%, 66.5%, and 62.0% in period 1, 2, and 3, respectively. MTA use for intermediate stages increased with the passage of time ( p = 0.052). The proportion of multiple MTAs use was remarkably increased in the 3 groups (1.1%, 10.2%, and 42.6%, respectively, p < 0.0001). Child-Pugh score, proportion of macrovascular invasion, extrahepatic metastasis, and α-fetoprotein (AFP) ≥400 ng/mL showed no significant difference among the 3 groups. The median overall survival was 11.9 months for the entire cohort and 10.4, 11.3, and 15.2 months, for period 1, 2, and 3, respectively. It is noteworthy that the prognosis of patients with HCC improved over time ( p = 0.016). With respect to progression-free survival, the median value was 3.0 months for the entire cohort and 2.7, 2.8, and 4.7 months for period 1, 2, and 3, respectively ( p < 0.0001). The treatment duration was also prolonged with time (2.7, 3.2, and 6.6 months for period 1, 2, and 3, respectively; p < 0.0001). Multivariate analysis using Cox proportional hazard model showed that HCV infection, Child-Pugh score, performance status, α-fetoprotein ≥400 ng/mL, presence of macrovascular invasion, and period 3 for initial MTA introduction were independent prognostic factors. Conclusions: Sequential therapy with multiple MTAs has gained popularity with time and is considered to improve patient prognosis. The development of MTA therapy for HCC is expected to continue. Therefore, further studies are needed to help determine the appropriate drugs, the sequence of MTA use, and the precise transition time.
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Dubuissez, Marion, Ingrid Loison, Sonia Paget, Han Vorng, Saliha Ait-Yahia, Olivier Rohr, Anne Tsicopoulos et Dominique Leprince. « Protein Kinase C-Mediated Phosphorylation of BCL11B at Serine 2 Negatively Regulates Its Interaction with NuRD Complexes during CD4+T-Cell Activation ». Molecular and Cellular Biology 36, no 13 (9 mai 2016) : 1881–98. http://dx.doi.org/10.1128/mcb.00062-16.
Texte intégralRésumé :
The transcription factor BCL11B/CTIP2 is a major regulatory protein implicated in various aspects of development, function and survival of T cells. Mitogen-activated protein kinase (MAPK)-mediated phosphorylation and SUMOylation modulate BCL11B transcriptional activity, switching it from a repressor in naive murine thymocytes to a transcriptional activator in activated thymocytes. Here, we show that BCL11B interacts via its conserved N-terminal MSRRKQ motif with endogenous MTA1 and MTA3 proteins to recruit various NuRD complexes. Furthermore, we demonstrate that protein kinase C (PKC)-mediated phosphorylation of BCL11B Ser2 does not significantly impact BCL11B SUMOylation but negatively regulates NuRD recruitment by dampening the interaction with MTA1 or MTA3 (MTA1/3) and RbAp46 proteins. We detected increased phosphorylation of BCL11B Ser2 uponin vivoactivation of transformed and primary human CD4+T cells. We show that following activation of CD4+T cells, BCL11B still binds toIL-2andId2promoters but activates their transcription by recruiting P300 instead of MTA1. Prolonged stimulation results in the direct transcriptional repression ofBCL11Bby KLF4. Our results unveil Ser2 phosphorylation as a new BCL11B posttranslational modification linking PKC signaling pathway to T-cell receptor (TCR) activation and define a simple model for the functional switch of BCL11B from a transcriptional repressor to an activator during TCR activation of human CD4+T cells.
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Godsey, Michael H., Natalya N. Baranova, Alexander A. Neyfakh et Richard G. Brennan. « Crystal Structure of MtaN, a Global Multidrug Transporter Gene Activator ». Journal of Biological Chemistry 276, no 50 (1 octobre 2001) : 47178–84. http://dx.doi.org/10.1074/jbc.m105819200.
Texte intégralRésumé :
MtaN (Multidrug Transporter Activation, N terminus) is a constitutive, transcriptionally active 109-residue truncation mutant, which contains only the N-terminal DNA-binding and dimerization domains of MerR family member Mta. The 2.75 Å resolution crystal structure of apo-MtaN reveals a winged helix-turn-helix protein with a protruding 8-turn helix (α5) that is involved in dimerization by the formation of an antiparallel coiled-coil. The hydrophobic core and helices α1 through α4 are structurally homologous to MerR family member BmrR bound to DNA, whereas one wing (Wing 1) is shifted. Differences between the orientation of α5 with respect to the core and the revolution of the antiparallel coiled-coil lead to significantly altered conformations of MtaN and BmrR dimers. These shifts result in a conformation of MtaN that appears to be incompatible with the transcription activation mechanism of BmrR and suggest that additional DNA-induced structural changes are necessary.
Thèses sur le sujet "N-MTAA"
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DE, VICO LUCA. « Biological Photoreceptors as Models for the Computer Design of Light Driven Molecular Rotors ». Doctoral thesis, Università di Siena, 2005. http://hdl.handle.net/11365/1006844.
Texte intégralRésumé :
This thesis represents a step towards the detailed comprehension of the photoisomerization processes and their exploitation. State-of-the-art ab initio quantum chemical calculations will be used to achieve various objectives. When a molecule undergoes an excitation to an higher electronic energy level, one of the main features to study is the way followed by the molecule to relax back on the electronic fundamental state. This implies the computation of the molecular structures where radiationless deactivation is most probable: conical intersections and singlet/triplet crossings. Such crossings provide effective channels for the radiationless deactivation to the ground state. During the last fifteen years the quantum chemical methods mentioned above have been successfully applied to the investigation of the mechanism of both the internal conversion and
photochemical transformation of isolated molecules. First objective of this thesis is about retinal chromophores and the relationship between their structure and the ultrafastness and stereospecificity of the photoisomerization in the protein environment. The acquired experience will be used to investigate for possible applications of molecules that can undergo a cis-trans photoisomerization. In fact, the second objective of this thesis is the study of a chromophore, N-methylthioacetammide
(NMTAA), model for a thio-substituted peptide bond. The last part of the thesis, and its third objective, is committed to the development of new tools for the geometry optimization of potential energy surfaces crossings, with high level ab initio computations.