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1.
Evaluation of a temperate-environment test of heat tolerance in prior heatstroke patients and controls 总被引:1,自引:0,他引:1
Lawrence E. Armstrong Roger W. Hubbard Elaine L. Christensen Jane P. De Luca 《European journal of applied physiology and occupational physiology》1990,60(3):202-208
It has been reported that scores from a temperate-environment step test describe the heat-tolerance status of prior heatstroke patients (HP). This investigation evaluated the ability of this temperate-environment heat-tolerance test (HTT) to indicate altered heart rate (HR) and rectal temperature (Tre) responses of HP, after 7 days of heat acclimation. On day 1, ten male HP (61 +/- 7 days post-heatstroke) and five control subjects (C) bench-stepped (0.30 m high, 27 steps.min-1) for 15 min (25.8 degrees C dry bulb, 16.2 degrees C wet bulb). On days 2-8, subjects underwent heat acclimation (40.1 degrees C dry bulb, 23.8 degrees C wet bulb; treadmill, 90 min.day-1). Heat acclimation resulted in significant decreases in final HR (152 +/- 5 vs 130 +/- 3 beats.min-1, P less than 0.025) and final Tre (38.62 +/- 0.11 vs 38.13 +/- 0.07 degrees C, p less than 0.01) in HP. One HP but no C was defined heat intolerant, exhibiting inability to adapt to daily exercise in the heat. On day 9, HP repeated HTT, exactly as performed on day 1; mean group HTT scores did not change (day 1 = 39 +/- 6; day 9 = 48 +/- 6, P greater than 0.05). All physical characteristics and physiological responses of HP (days 1, 2, 7, 9) were statistically similar (P greater than 0.05) to those of C. In contrast to heat-acclimation data, HTT scores (score less than or equal to 30) indicated that four HP were heat intolerant on day 1 and two HP were heat intolerant on day 9.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
2.
Martin Roesslein Christian Froehlich Frank Jans Tobias Piegeler Ulrich Goebel Torsten Loop 《Life sciences》2014
Aims
Dobutamine is cytoprotective when applied before a subsequent stress. However, the underlying molecular mechanism is unknown. Dobutamine also inhibits nuclear factor (NF)-κB in human T lymphocytes. Other inhibitors of NF-κB induce a so-called heat shock response. We hypothesized that dobutamine mediates protection from apoptotic cell death by the induction of a heat shock response.Main methods
Jurkat T lymphoma cells were preincubated with dobutamine (0.1, 0.5 mM) before the induction of apoptosis (staurosporine, 2 μM). DNA-binding of heat shock factor (HSF)-1 was analyzed by electrophoretic mobility shift assay, mRNA-expression of heat shock protein (hsp)70 and hsp90 by Northern Blot, activity of caspase-3 by fluorogenic caspase activity assay and cleavage of pro-caspase-3 by Western Blot. Apoptosis was assessed by flow cytometry after annexin V-fluorescein isothiocyanate staining. Hsp70 and hsp90 were inhibited using N-formyl-3,4-methylenedioxy-benzylidene-gamma-butyrolaetam and 17-allylamino-17-demethoxygeldana-mycin, respectively. All data are given as median and 25/75% percentile.Key findings
Pre-incubation with dobutamine inhibited staurosporine-induced annexin V-fluorescence (28 [20–32] % vs. 12 [9–15] % for dobutamine 0.1 mM and 7 [5–12] % for dobutamine 0.5 mM, p < 0.001), cleavage of pro-caspase-3 as well as caspase-3-like activity (0.46 [0.40–0.48] vs. 0.32 [0.27–0.39] for Dobutamine 0.1 mM and 0.20 [0.19–0.23] for Dobutamine 0.5 mM, p < 0.01). Dobutamine induced DNA-binding of HSF-1 and mRNA-expression of hsp70 and hsp90. While inhibition of Hsp90 had no effect, inhibition of Hsp70 increased the number of annexin V-positive cells (33 [32–36] % vs. 18 [16–24] %) and caspase-3-like activity (0.21 [0.19–0.23] vs. 0.16 [0.13–0.17], p < 0.05).Significance
Dobutamine protects from apoptotic cell death via the induction of Hsp70. 相似文献3.
Yao-Hsuan Tseng Der-Shan Sun Wen-Shiang Wu Hao Chan Ming-Syuan Syue Han-Chen Ho Hsin-Hou Chang 《Biochimica et Biophysica Acta (BBA)/General Subjects》2013
Background
Traditional antibacterial photocatalysts are primarily induced by ultraviolet light to elicit antibacterial reactive oxygen species. New generation visible-light responsive photocatalysts were discovered, offering greater opportunity to use photocatalysts as disinfectants in our living environment. Recently, we found that visible-light responsive platinum-containing titania (TiO2–Pt) exerted high performance antibacterial property against soil-borne pathogens even in soil highly contaminated water. However, its physical and photocatalytic properties, and the application in vivo have not been well-characterized.Methods
Transmission electron microscopy, energy dispersive spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, ultraviolet–visible absorption spectrum and the removal rate of nitrogen oxides were therefore analyzed. The antibacterial performance under in vitro and in vivo conditions was evaluated.Results
The apparent quantum efficiency for visible light illuminated TiO2–Pt is relatively higher than several other titania photocatalysts. The killing effect achieved approximately 2 log reductions of pathogenic bacteria in vitro. Illumination of injected TiO2–Pt successfully ameliorated the subcutaneous infection in mice.Conclusions
This is the first demonstration of in vivo antibacterial use of TiO2–Pt nanoparticles. When compared to nanoparticles of some other visible-light responsive photocatalysts, TiO2–Pt nanoparticles induced less adverse effects such as exacerbated platelet clearance and hepatic cytotoxicity in vivo.General significance
These findings suggest that the TiO2–Pt may have potential application on the development of an antibacterial material in both in vitro and in vivo settings. 相似文献4.
Aims
Data on the association between the ghrelin Leu72Met polymorphism and type 2 diabetes are conflicting. A meta-analysis was performed on this topic.Methods
We searched for case–control studies using electronic databases (Medline and PubMed) and reference lists of studies. Odds ratios (OR) and 95% confidence intervals (CI) assuming dominant, recessive and homozygote comparison genetic models were calculated.Results
Six case–control studies involving a total of 3417 cases and 3081 controls were included in this meta-analysis. No association was found between the ghrelin Leu72Met polymorphism and type 2 diabetes risk in the overall population in dominant, recessive and homozygote comparison models. However, in subgroup analyses stratified by ethnicity, we found that the risk for type 2 diabetes was decreased in subjects with Met72 + genotypes in Caucasians (OR = 0.79, 95% CI: 0.64–0.98, Pz = 0.030).Conclusion
The ghrelin Leu72Met polymorphism was protective against type 2 diabetes in Caucasians. Future studies performed in larger sample size are needed to allow a more definitive conclusion. 相似文献5.
Tristan Richard Yorgos PapastamoulisPierre Waffo-Teguo Jean-Pierre Monti 《Biochimica et Biophysica Acta (BBA)/General Subjects》2013
Background
Alzheimer's disease (AD) is a progressive neurodegenerative disorder. There is a consensus that Aβ is a pathologic agent and that its toxic effects, which are at present incompletely understood, may occur through several potential mechanisms. Polyphenols are known to have wide-ranging properties with regard to health and for helping to prevent various diseases like neurodegenerative disorders. Thus inhibiting the formation of toxic Aβ assemblies is a reasonable hypothesis to prevent and perhaps treat ADMethods
Solution NMR and molecular modeling were used to obtain more information about the interaction between the Aβ1–40 and the polyphenol ε-viniferin glucoside (EVG) and particularly the Aβ residues involved in the complex.Results
The study demonstrates the formation of a complex between two EVG molecules and Aβ1–40 in peptide characteristic regions that could be in agreement with the inhibition of aggregation. Indeed, in previous studies, we reported that EVG strongly inhibited in vitro the fibril formation of the full length peptides Aβ1–40 and Aβ1–42, and had a strong protective effect against PC12 cell death induced by these peptides.Conclusion
For the full length peptide Aβ1–40, the binding sites observed could explain the EVG inhibitory effect on fibrillization and thus prevent amyloidogenic neurotoxicity.General significance
Even though this interaction might be important at the biological level to explain the protective effect of polyphenols in neurodegenerative diseases, caution is required when extrapolating this in vitro model to human physiology. 相似文献6.
Cláudia N. Ferreira Maria G. Carvalho Ana P. Fernandes Izabela R. Santos Kathryna F. Rodrigues Ângela M.Q. Lana Cristina R. Almeida Andréia A. Loures-Vale Karina B. Gomes Marinez O. Sousa 《Gene》2013
Background
Polymorphisms in apolipoprotein A5 gene (APOA5) have been associated with higher triglyceride levels in many populations. The aim of the study was to determine the allelic and genotypic distribution of the APOA5 − 1131T > C polymorphism and to identify the association of the genetic variant and the risk for dyslipidemia.Methods
We genotyped 109 dyslipidemic subjects and 107 controls. The total cholesterol, triglycerides and HDL-c were determined enzymatically. Comparison of means among groups was calculated by ANOVA. Significant differences among groups were evaluated by Student–Newman–Keuls test.Results
The minor allele C was more frequent in dyslipidemic subjects than controls (p = 0.019) and confers an increased individual risk for dyslipidemia (OR = 1.726, CI 95% = 1.095–2.721). The genotype analysis by gender showed that this allele was more frequent in dyslipidemic males (p = 0.037; OR = 2.050, CI 95% = 1.042–4.023). When participants were analyzed according to genotypes TT and TC/CC, C-carriers presented higher cholesterol and triglycerides levels than TT homozygous (p = 0.046 and 0.049, respectively).Conclusions
The allele C confers higher total cholesterol and triglycerides levels in dyslipidemic adults. The APOA5 − 1131T > C polymorphism is associated with dyslipidemia in male subjects. 相似文献7.
Introduction
This study investigated the test–retest reliability for assessment of postural stability using a quantitative method for identification of center of pressure (CoP) spatial patterns of three-dimensional statokinesigrams (3D-SKG).Methods
Twenty-one healthy participants (11 women, age 26.8±7.2 years, body mass index 25.6±5.3 kg/m²) were submitted to four consecutive 60-s trials while performing undisturbed upright stance with feet together, with or without visual input each. CoP data was used to calculate parameters from the 3D-SKG (quantity of high-density regions, nHDR). Stabilogram (standard deviation, range, maximum velocity) and statokinesigram (elliptical area, average velocity) were also calculated. Intraclass correlation coefficients (ICC2,1 and ICC2,4) and repeated-measures analysis-of-variance were used for statistical analysis.Results
Significant differences in nHDR among trials were not noticed in both protocols, as well as for any parameter of the stabilogram or statokinesigram (all P>0.05). Reliability for identification of nHDR with or without visual input was either excellent (ICC2,4=0.844 and 0.792, respectively) or fair to good (ICC2,1=0.575 and 0.488, respectively). Reliability of parameters from stabilogram and statokinesigram varied from excellent to poor for either postural task with (ICC2,4 range: 0.961–0.491; ICC2,1 range: 0.859–0.194) or without visual input (ICC2,4 range: 0.990–0.444; ICC2,1 range: 0.960–0.166).Conclusions
Test–retest reliability for identification of CoP spatial patterns is excellent or fair to good using averaged or single measurements of nHDR, respectively. No learning effect on repeated trials for identification of CoP spatial patterns was detected but deserves further research. 相似文献8.
Thiago C. Genaro-Mattos Luana T. Dalvi Ricardo G. Oliveira Janini S. Ginani Marcelo Hermes-Lima 《Biochimica et Biophysica Acta (BBA)/General Subjects》2009,1790(12):1636-1642
Background
The 2-deoxyribose (2-DR) degradation assay is a widely used test for determining anti/pro-oxidant properties of molecules and plant extracts. Most reports use reaction blanks omitting 2-DR or thiobarbituric acid (TBA). However, when studying Fe(II)-mediated reactions, we verified that these blanks are not appropriate. Fe(III) – a product of these reactions – causes a relevant artifact in the assay, where 2-DR is oxidized by Fe(III).Method
2-DR degradation was determined at 532 nm as TBA-reactive substances.Results and conclusion
HPLC determinations indicated that Fe(III) added after or before TBA generates considerable amounts of malondialdehyde (2-DR degradation product) in comparison with assays employing Fenton reagents or Fe(II) autoxidation. Addition of catalase and thiourea has no effect on Fe(III)-induced 2-DR degradation indicating lack of ROS involvement. This Fe(III)-mediated 2-DR damage is dependent on iron and 2-DR concentrations, but not on H2O2, buffer composition or iron-chelators. Depending on the assay conditions Fe(III)-interference accounts for 20% to 90% of 2-DR degradation mediated by Fe(II).Significance
A new reaction blank is proposed herein–based on the use of Fe(III)–for the assay. The lack of such correction has caused the underestimation of antioxidant capacity of various compounds in many studies in the last 2 decades. 相似文献9.
Akira Matsumoto Hiroko MatsumotoYasuhiro Maeda Yuji Miyahara 《Biochimica et Biophysica Acta (BBA)/General Subjects》2013
Background
Field effect transistor (FET) based signal-transduction (Bio-FET) is an emerging technique for label-free and real-time basis biosensors for a wide range of targets. Glucose has constantly been of interest due to its clinical relevance. Use of glucose oxidase (GOD) and a lectin protein Concanavalin A are two common strategies to generate glucose-dependent electrochemical events. However, these protein-based materials are intolerant of long-term usage and storage due to their inevitable denaturing.Methods
A phenylboronic acid (PBA) modified self-assembled monolayer (SAM) on a gold electrode with an optimized disassociation constant of PBA, that is, 3-fluoro-4-carbamoyl-PBA possessing its pKa of 7.1, was prepared and utilized as an extended gate electrode for Bio-FET.Results
The prepared electrode showed a glucose-dependent change in the surface potential under physiological conditions, thus providing a remarkably simple rationale for the glyco-sensitive Bio-FET. Importantly, the PBA modified electrode showed tolerance to relatively severe heat and drying treatments; conditions under which protein based materials would surely be denatured.Conclusions
A PBA modified SAM with optimized disassociation constant (pKa) can exhibit a glucose-dependent change in the surface potential under physiological conditions, providing a remarkably simple but robust method for the glyco-sensing.General significance
This protein-free, totally synthetic glyco-sensing strategy may offer cheap, robust and easily accessible platform that may be useful in developing countries. This article is part of a Special Issue entitled Organic Bioelectronics—Novel Applications in Biomedicine. 相似文献10.
Ashutosh Pandey Swati Chandra Lalit Kumar Singh Chauhan Gopeshwar Narayan Debapratim Kar Chowdhuri 《Biochimica et Biophysica Acta (BBA)/General Subjects》2013
Background
Amorphous silica nanoparticles (aSNPs) are used for various applications including food industry. However, limited in vivo studies are available on absorption/internalization of ingested aSNPs in the midgut cells of an organism. The study aims to examine cellular uptake of aSNPs (< 30 nm) in the midgut of Drosophila melanogaster (Oregon R+) owing to similarities between the midgut tissue of this organism and human and subsequently cellular stress response generated by these nanoparticles.Methods
Third instar larvae of D. melanogaster were exposed orally to 1–100 μg/mL of aSNPs for 12–36 h and oxidative stress (OS), heat shock genes (hsgs), membrane destabilization (Acridine orange/Ethidium Bromide staining), cellular internalization (TEM) and apoptosis endpoints.Results
A significant increase was observed in OS endpoints in the midgut cells of exposed Drosophila in a concentration- and time-dependent manner. Significantly increased expression of hsp70 and hsp22 along with caspases activation, membrane destabilization and mitochondrial membrane potential loss was also observed. TEM analysis showed aSNPs-uptake in the midgut cells of exposed Drosophila via endocytic vesicles and by direct membrane penetration.Conclusion
aSNPs after their internalization in the midgut cells of exposed Drosophila larvae show membrane destabilization along with increased cellular stress and cell death.General significance
Ingested aSNPs show adverse effects on the cells of GI tract of the exposed organism thus their industrial use as a food-additive may raise concern to human health. 相似文献11.
Bennett L. Ibey Andrei G. Pakhomov Betsy W. Gregory Vera A. Khorokhorina Caleb C. Roth Mikhail A. Rassokhin Joshua A. Bernhard Gerald J. Wilmink Olga N. Pakhomova 《Biochimica et Biophysica Acta (BBA)/General Subjects》2010
Background
Nanosecond electric pulses (EP) disrupt cell membrane and organelles and cause cell death in a manner different from the conventional irreversible electroporation. We explored the cytotoxic effect of 10-ns EP (quantitation, mechanisms, efficiency, and specificity) in comparison with 300-ns, 1.8- and 9-μs EP.Methods
Effects in Jurkat and U937 cells were characterized by survival assays, DNA electrophoresis and flow cytometry.Results
10-ns EP caused apoptotic or necrotic death within 2–20 h. Survival (S, %) followed the absorbed dose (D, J/g) as: S = αD(−K), where coefficients K and α determined the slope and the “shoulder” of the survival curve. K was similar in all groups, whereas α was cell type- and pulse duration-dependent. Long pulses caused immediate propidium uptake and phosphatidylserine (PS) externalization, whereas 10-ns pulses caused PS externalization only.Conclusions
1.8- and 9-μs EP cause cell death efficiently and indiscriminately (LD50 1–3 J/g in both cell lines); 10-ns EP are less efficient, but very selective (LD50 50–80 J/g for Jurkat and 400–500 J/g for U937); 300-ns EP show intermediate effects. Shorter EP open propidium-impermeable, small membrane pores (”nanopores”), triggering different cell death mechanisms.General significance
Nanosecond EP can selectively target certain cells in medical applications like tumor ablation. 相似文献12.
13.
Geovanna Nallely Quiñonez-Bastidas Claudia Cervantes-Durán Héctor Isaac Rocha-González Janet Murbartián Vinicio Granados-Soto 《Life sciences》2013
Aims
The purpose of this study was to investigate the antinociceptive effect of epicatechin as well as the possible mechanisms of action in diabetic rats.Main methods
Rats were injected with streptozotocin to produce hyperglycemia. The formalin test was used to assess the nociceptive activity.Key findings
Acute pre-treatment with epicatechin (0.03–30 mg/kg, i.p.) prevented formalin-induced nociception in diabetic rats. Furthermore, daily or every other day treatment for 2 weeks with epicatechin (0.03–30 mg/kg, i.p.) also prevented formalin-induced nociception in diabetic rats. Acute epicatechin-induced antinociception was prevented by l-NAME (Nω-nitro-l-arginine methyl ester hydrochloride, 1–10 mg/kg, non-selective nitric oxide synthesis inhibitor), 7-nitroindazole (0.1–1 mg/kg, selective neuronal nitric oxide synthesis inhibitor), ODQ (1H-(1,2,4)-oxadiazolo(4,2-a)quinoxalin-1-one, 0.2–2 mg/kg, guanylyl cyclase inhibitor) or glibenclamide (1–10 mg/kg, ATP-sensitive K+ channel blocker). Moreover, epicatechin (3 mg/kg)-induced antinociception was fully prevented by methiothepin (0.1–1 mg/kg, serotonergic receptor antagonist), WAY-100635 (0.03–0.3 mg/kg, selective 5-HT1A receptor antagonist) or SB-224289 (0.03–0.3 mg/kg, selective 5-HT1B receptor antagonist). In contrast, BRL-15572 (0.03–0.3 mg/kg, selective 5-HT1D receptor antagonist) only slightly prevented the antinociceptive effect of epicatechin. Naloxone (0.1–1 mg/kg, opioid antagonist) did not modify epicatechin's effect.Significance
Data suggest the involvement of the nitric oxide–cyclic GMP–K+ channel pathway as well as activation of 5-HT1A and 5HT1B, and at a lesser extent, 5-HT1D, but not opioid, receptors in the antinociceptive effect of epicatechin in diabetic rats. Our data suggest that acute or chronic treatment with epicatechin may prove to be effective to treat nociceptive hypersensitivity in diabetic patients. 相似文献14.
Yu-Shiun Lin Li-Chu Tsai Shu-Hua Lee Hanna S. Yuan Lie-Fen Shyur 《Biochimica et Biophysica Acta (BBA)/General Subjects》2009
Background
Fibrobacter succinogenes 1,3-1,4-β-d-glucanase (Fsβ-glucanase) is the only naturally occurring circularly permuted β-glucanase among bacterial glucanases with reverse protein domains. We characterized the functional and structural significance of residues 200–209 located in the domain B of Fsβ-glucanase, corresponding to the major surface loop in the domain A region of Bacillus licheniformis glucanase.Methods
Rational design approaches including site-directed mutagenesis, initial-rate kinetics, and structural modeling analysis were used in this study.Results
Our kinetic data showed that D202N and D206N exhibited a 1.8- and 1.5-fold increase but G207N, G207−, F205L, N208G and T204F showed a 7.0- to 2.2-fold decrease, in catalytic efficiency (kcat/KM) compared to the wild-type enzyme. The comparative energy ΔΔGb value in individual mutant enzymes was well correlated to their catalytic efficiency. D206R mutant enzyme exhibited the highest relative activity at 50 °C over 10 min, whereas K200F was the most heat-sensitive enzyme.Conclusions
This study demonstrates that Phe205, Gly207, and Asn208 in the Type II turn of the connecting loop may play a role in the catalytic function of Fsβ-glucanase.General significance
Residues 200–209 in Fsβ-glucanase resided at the similar structural topology to that of Bacillus enzyme were found to play some similar catalytic function in glucanase. 相似文献15.
Andrea Ilari Flaminia Alaleona Giancarlo Tria Patrizia Petrarca Andrea Battistoni Carlotta Zamparelli Daniela Verzili Mattia Falconi Emilia Chiancone 《Biochimica et Biophysica Acta (BBA)/General Subjects》2014
Background
In Gram-negative bacteria the ZnuABC transporter ensures adequate zinc import in Zn(II)-poor environments, like those encountered by pathogens within the infected host. Recently, the metal-binding protein ZinT was suggested to operate as an accessory component of ZnuABC in periplasmic zinc recruitment. Since ZinT is known to form a ZinT–ZnuA complex in the presence of Zn(II) it was proposed to transfer Zn(II) to ZnuA. The present work was undertaken to test this claim.Methods
ZinT and its structural relationship with ZnuA have been characterized by multiple biophysical techniques (X-ray crystallography, SAXS, analytical ultracentrifugation, fluorescence spectroscopy).Results
The metal-free and metal-bound crystal structures of Salmonella enterica ZinT show one Zn(II) binding site and limited structural changes upon metal removal. Spectroscopic titrations with Zn(II) yield a KD value of 22 ± 2 nM for ZinT, while those with ZnuA point to one high affinity (KD < 20 nM) and one low affinity Zn(II) binding site (KD in the micromolar range). Sedimentation velocity experiments established that Zn(II)-bound ZinT interacts with ZnuA, whereas apo-ZinT does not. The model of the ZinT–ZnuA complex derived from small angle X-ray scattering experiments points to a disposition that favors metal transfer as the metal binding cavities of the two proteins face each other.Conclusions
ZinT acts as a Zn(II)-buffering protein that delivers Zn(II) to ZnuA.General significance
Knowledge of the ZinT–ZnuA relationship is crucial for understanding bacterial Zn(II) uptake. 相似文献16.
Aribam Swarmistha Devi Yohsuke Ogawa Yoshihiro Shimoji Subramanian Balakumar Karthe Ponnuraj 《Biochimica et Biophysica Acta (BBA)/General Subjects》2012
Background
Pathogenic bacteria specifically recognize extracellular matrix (ECM) molecules of the host (e.g. collagen, fibrinogen and fibronectin) through their surface proteins known as MSCRAMMs (Microbial Surface Components Recognizing Adhesive Matrix Molecules) and initiate colonization. On implantation, biomaterials easily get coated with these ECM molecules and the MSCRAMMs mediate bacterial adherence to biomaterials. With the rapid rise in antibiotic resistance, designing alternative strategies to reduce/eliminate bacterial colonization is absolutely essential.Methods
The Rhusiopathiae surface protein B (RspB) is a collagen‐binding MSCRAMM of Erysipelothrix rhusiopathiae. It also binds to abiotic surfaces. The crystal structure of the collagen‐binding region of RspB (rRspB31–348) reported here revealed that RspB also binds collagen by a unique ligand binding mechanism called “Collagen Hug” which is a common theme for collagen‐binding MSCRAMMs of many Gram-positive bacteria. Here, we report the interaction studies between rRspB31–348 and silver nanoparticles using methods like gel shift assay, gel permeation chromatography and circular dichroism spectroscopy.Results
The “Collagen Hug” mechanism was inhibited in the presence of silver nanoparticles as rRspB31–348 was unable to bind to collagen. The total loss of binding was likely because of rRspB31–348 and silver nanoparticle protein corona formation and not due to the loss of the structural integrity of rRspB31–348 on binding with nanoparticles as observed from circular dichroism experiments.General significance
Interaction of rRspB31–348 with silver nanoparticle impaired its ligand binding mechanism. Details of this inhibition mechanism may be useful for the development of antimicrobial materials and antiadhesion drugs. 相似文献17.
Valentina Bosello-Travain Marcus Conrad Giorgio Cozza Alessandro Negro Silvia Quartesan Monica Rossetto Antonella Roveri Stefano Toppo Fulvio Ursini Mattia Zaccarin Matilde Maiorino 《Biochimica et Biophysica Acta (BBA)/General Subjects》2013
Background
Mammalian GPx7 is a monomeric glutathione peroxidase of the endoplasmic reticulum (ER), containing a Cys redox center (CysGPx). Although containing a peroxidatic Cys (CP) it lacks the resolving Cys (CR), that confers fast reactivity with thioredoxin (Trx) or related proteins to most other CysGPxs.Methods
Reducing substrate specificity and mechanism were addressed by steady-state kinetic analysis of wild type or mutated mouse GPx7. The enzymes were heterologously expressed as a synuclein fusion to overcome limited expression. Phospholipid hydroperoxide was the oxidizing substrate. Enzyme–substrate and protein–protein interaction were analyzed by molecular docking and surface plasmon resonance analysis.Results
Oxidation of the CP is fast (k+ 1 > 103 M− 1 s− 1), however the rate of reduction by GSH is slow (k′+ 2 = 12.6 M− 1 s− 1) even though molecular docking indicates a strong GSH–GPx7 interaction. Instead, the oxidized CP can be reduced at a fast rate by human protein disulfide isomerase (HsPDI) (k+ 1 > 103 M− 1 s− 1), but not by Trx. By surface plasmon resonance analysis, a KD = 5.2 μM was calculated for PDI–GPx7 complex. Participation of an alternative non-canonical CR in the peroxidatic reaction was ruled out. Specific activity measurements in the presence of physiological reducing substrate concentration, suggest substrate competition in vivo.Conclusions
GPx7 is an unusual CysGPx catalyzing the peroxidatic cycle by a one Cys mechanism in which GSH and PDI are alternative substrates.General significance
In the ER, the emerging physiological role of GPx7 is oxidation of PDI, modulated by the amount of GSH. 相似文献18.
Purpose
A number of studies reported on associations of single nucleotide polymorphisms (SNPs) present in chromosome 9p21 with early-onset coronary artery disease (CAD). The present study was then undertaken to perform a meta-analysis of all the results published to date.Methods
All studies of the 9p21 association with early-onset CAD that were published between 2007 and 2012 were retrieved from the PubMed database. RevMan 5.0 software was used to perform meta-analysis of the data that fulfilled the criteria for our meta-analysis. The effect size of four SNPs in the 9p21 region on early-onset CAD risk was assessed based on the odds ratios (ORs) with calculation of 95% confidence interval (CI).Results
A total of 7123 subjects from 7 case–control studies were genotyped. Meta-analysis demonstrated disease association for rs2383207 (OR = 0.79, 95% CI 0.71–0.88, P < 0.0001), rs2383206 (OR = 1.17, 95% CI 1.10–1.25, P < 0.00001), rs10757278 (OR = 1.28, 95% CI 1.15–1.42, P < 0.00001), and rs10757274 (OR = 1.17, 95% CI 1.08–1.33, P = 0.02).Conclusion
Genetic variation in the chromosome 9p21 region may contribute to the etiology of early-onset CAD although their effect size is rather small. 相似文献19.
Gilda Karimi Chantal Houée Levin Marie Claire Dagher Laura Baciou Tania Bizouarn 《Biochimica et Biophysica Acta (BBA)/General Subjects》2014
Background
The phagocyte NADPH-oxidase is a multicomponent enzyme that generates superoxide anions. It comprises a membrane redox component flavocytochrome b558 and four cytosolic proteins (p67phox, p47phox, p40phox and Rac) that must assemble to produce an active system. In this work we focused on the spatio-temporal control of the activation process of phagocyte NADPH oxidase.Methods
A wide range of techniques including fast kinetics with a stopped-flow apparatus and various combinations of the activating factors was used to test the order of assembly and the role of the p47phox–p67phox complex.Results
The data presented here are consistent with the absence of a catalytic role of the p47phox–p67phox interacting state and support the idea of independent binding sites for the cytosolic proteins on the flavocytochrome b558 allowing random binding order. However, the formation of the active complex appears to involve a synergistic process of binding of the activated cytosolic subunits to cytochrome b558. All partners should be in the vicinity for optimal assembly, a delay or the absence of one of the partners in this process seems to lead to a decrease in the efficiency of the catalytic core.Conclusion and general significance
The activation and assembly of the NADPH oxidase components have to be achieved simultaneously for the formation of an efficient and optimal enzyme complex. This mechanism appears to be incompatible with continuous fast exchanges of the cytosolic proteins during the production of superoxide ion in the phagosome. 相似文献20.