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81.
Valente F Lago BV Castro CA Almeida AJ Gomes SA Soares CC 《Memórias do Instituto Oswaldo Cruz》2010,105(8):970-977
An estimated 360 million people are infected with hepatitis B virus (HBV) worldwide. Among these, 65 million live in Africa. Despite the high levels of hepatitis B in Africa, HBV epidemiology is still poorly documented in most African countries. In this work, the epidemiological and molecular characteristics of HBV infection were evaluated among the staff, visitors and adult patients (n = 508) of a public hospital in Luanda, Angola. The overall prevalence of hepatitis B core antibody (anti-HBc) and hepatitis B surface antigen was 79.7% and 15.1%, respectively. HBV infection was higher in males and was more prevalent in individuals younger than 50 years old. HBV-DNA was detected in 100% of HBV "e" antigen-positive serum samples and in 49% of anti-hepatitis Be antibody-positive samples. Thirty-five out of the 40 HBV genotypes belonged to genotype E. Circulation of genotypes A (4 samples) and D (1 sample) was also observed. The present study demonstrates that HBV infection is endemic in Luanda, which has a predominance of genotype E. This genotype is only sporadically found outside of Africa and is thought to have emerged in Africa at a time when the trans-Atlantic slave trade had stopped. 相似文献
82.
Calculating growth parameters of Genidens barbus (Siluriformes, Ariidae) using length composition and age data 总被引:1,自引:0,他引:1
The marine catfish Genidens barbus was once one of the most important estuarine fishery resources in the Patos Lagoon (southern Brazil), which had the largest population known for the species. However, clear signs of overfishing have been observed since the 1980s. Growth parameters for this population were estimated by combining length frequency data for juveniles and selected published data on annuli reading from adult otoliths. This methodology yielded a more realistic set of parameters using both the specialized and generalized von Bertalanffy growth model. The species growth can be described as: Lt = 118.6[1 − e−0.043(t+1.505)] or Lt = 104.6[1 −e−0.137D(t+4.013)]1/D with the surface factor D = 0.542. The growth performance index ϕ′ was estimated as 2.78 for the special (classical) model. Stock rebuilding is expected to be slow, as the species is slow‐growing, has a low natural mortality rate, and mouthbreeds a small amount of large eggs. 相似文献
83.
Velasco B Trujillo-Ferrara JG Castillo LH Miranda R Sánchez-Torres LE 《Life sciences》2007,80(11):1007-1013
Compounds containing B-N bonds have shown interesting biological activity. One class of such molecules is the 2,2-diphenyl-1,3,2-oxazaborolidin-5-ones (3a-j), which contain a B-N bond, have an alpha-amino acid moiety in the heterocycle, and have an exocyclic moiety related to an amino acid. The purpose of this work was to determine the inhibitory effects of 3a-j on the proliferation of murine L5178Y lymphoma cells. A new five-membered heterocyclic nucleus with apoptotic activity was found. The target products showed potent cytotoxicity in the L5178Y cell line. Among them, 3a exhibited the highest antineoplastic activity in L5178Y cells with an IC(50) value of 22.5+/-0.2 microM. 相似文献
84.
González Ramírez M Orozco Suárez S Salgado Ceballos H Feria Velasco A Rocha L 《Cellular and molecular neurobiology》2007,27(2):211-227
Effects of hyperthermia-induced seizures (HS) on GABAA and benzodiazepine (BDZ) receptor binding in immature rat brain were evaluated using in vitro autoradiography. HS were induced
in 10-days-old rats by a regulated stream of moderately heated air directed 50 cm above the animals. Rats were killed 30 min,
24 h or 20 days after HS and their brains were used for in vitro autoradiography experiments to determine GABAA and BDZ receptor binding. GABAA binding was significantly enhanced in all brain areas evaluated 30 min after HS, an effect that endures 24 h and 20 days
after seizures. Concerning BDZ receptor binding, a significant increase was detected in entorhinal and perirhinal cortices
and decreased in basolateral amygdala 30 min following HS. One day after HS, animals demonstrated enhanced BDZ binding in
the cingulate, frontal, posterior parietal, entorhinal, temporal and perirhinal cortices; striatum, accumbens, substantia
nigra pars compacta and amygdala nuclei. Twenty days after HS enhanced BDZ binding was restricted in the cingulated, frontal,
anterior and posterior parietal cortices, as well as in substantia nigra pars reticulata, whereas decreased values were found
in accumbens nucleus and substantia nigra pars compacta. Our data indicate differential effects of HS in GABAA and BDZ binding in immature brain. HS-induced GABAA and BDZ changes are different from those previously described in experimental models of temporal lobe epilepsy in adult animals. 相似文献
85.
The inner cavity of Escherichia coli DegP protein is not essential for molecular chaperone and proteolytic activity
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Jomaa A Damjanovic D Leong V Ghirlando R Iwanczyk J Ortega J 《Journal of bacteriology》2007,189(3):706-716
The Escherichia coli DegP protein is an essential periplasmic protein for bacterial survival at high temperatures. DegP has the unusual property of working as a chaperone below 28 degrees C, but efficiently degrading unfolded proteins above 28 degrees C. Monomeric DegP contains a protease domain and two PDZ domains. It oligomerizes into a hexameric cage through the staggered association of trimers. The active sites are located in a central cavity that is only accessible laterally, and the 12 PDZ domains act as mobile sidewalls that mediate opening and closing of the gates. As access to the active sites is restricted, DegP is an example of a self-compartmentalized protease. To determine the essential elements of DegP that maintain the integrity of the hexameric cage, we constructed several deletion mutants of DegP that formed trimers rather than hexamers. We found that residues 39 to 78 within the LA loops, as well as the PDZ2 domains are essential for the integrity of the DegP hexamer. In addition, we asked whether an enclosed cavity or cage of specific dimensions is required for the protease and chaperone activities in DegP. Both activities were maintained in the trimeric DegP mutants without an enclosed cavity and in deletion DegP mutants with significantly reduced dimensions of the cage. We conclude that the functional unit for the protease and chaperone activities of DegP is a trimer and that neither a cavity of specific dimensions nor the presence of an enclosed cavity appears to be essential for the protease and chaperone activities of DegP. 相似文献
86.
Kim SJ Zhang X Xu X Chen A Gonzalez JB Koul S Vijayan K Crystal GJ Vatner SF Hintze TH 《American journal of physiology. Heart and circulatory physiology》2007,292(5):H2152-H2158
Nitric oxide (NO) derived from endothelial NO synthase (NOS) (eNOS) has been identified as a trigger for the second window of protection (SWOP), but its role as a mediator during the SWOP is a matter of debate. Eighteen mongrel dogs were chronically instrumented to measure left ventricular function, coronary blood flow, and wall thickening. Myocardial preconditioning was induced by 10 min coronary artery occlusion. After 24 h of reperfusion (during the SWOP), the hearts were excised. Coronary microvessels were isolated and incubated in presence of 1) the endothelium-dependent agonists carbachol and bradykinin, 2) the calcium ionophore A23187, and 3) the angiotensin-converting enzyme (ACE) inhibitors enalaprilat and ramiprilat. Nitrite, a metabolite of NO, was measured. Under baseline conditions, nitrite production in microvessels from SWOP was 30% higher than that from normal (96 +/- 4 vs. 74 +/- 3 pmol/mg, P < 0.01, respectively). Nitrite production in response to carbachol, bradykinin, and A23187 was also enhanced in microvessels from SWOP (P < 0.05). These enhanced responses were abolished by N(G)-nitro-l-arginine methyl ester (l-NAME) or the endothelial receptor-specific antagonists atropine and HOE-140. The level of eNOS protein in the SWOP myocardium was twofold higher than that in the non-SWOP myocardium. Nitrite production in response to the ACE inhibitors was greater in microvessels from SWOP. These effects were blocked by l-NAME, HOE-140, or dichloroisocoumarin (which inhibits kinin formation). We found that a brief ischemic episode induced delayed, enhanced NO production in coronary microvessels and an upregulation of eNOS protein. These findings suggest that eNOS is a mediator during the SWOP. The ability of ACE inhibitors to enhance NO release during the SWOP points to an additional clinical application for these drugs. 相似文献
87.
88.
CD16 promotes Escherichia coli sepsis through an FcR gamma inhibitory pathway that prevents phagocytosis and facilitates inflammation 总被引:3,自引:0,他引:3
Pinheiro da Silva F Aloulou M Skurnik D Benhamou M Andremont A Velasco IT Chiamolera M Verbeek JS Launay P Monteiro RC 《Nature medicine》2007,13(11):1368-1374
Sepsis, a leading cause of death worldwide, involves proinflammatory responses and inefficient bacterial clearance. Phagocytic cells play a crucial part in the prevention of sepsis by clearing bacteria through host innate receptors. Here we show that the FcRgamma adaptor, an immunoreceptor tyrosine-based activation motif (ITAM)-bearing signal transduction subunit of the Fc receptor family, has a deleterious effect on sepsis. FcRgamma(-/-) mice show increased survival during peritonitis, owing to markedly increased E. coli phagocytosis and killing and to lower production of the proinflammatory cytokine tumor necrosis factor (TNF)-alpha. The FcRgamma-associated receptor that inhibits E. coli phagocytosis is FcgammaRIII (also called CD16), and its absence protects mice from sepsis. FcgammaRIII binds E. coli, and this interaction induces FcRgamma phosphorylation, recruitment of the tyrosine phosphatase SHP-1 and phosphatidylinositide-3 kinase (PI3K) dephosphorylation. Decreased PI3K activity inhibits E. coli phagocytosis and increases TNF-alpha production through Toll-like receptor 4. We identified the phagocytic receptor negatively regulated by FcRgamma on macrophages as the class A scavenger receptor MARCO. E. coli-FcgammaRIII interaction induces the recruitment of SHP-1 to MARCO, thereby inhibiting E. coli phagocytosis. Thus, by binding FcgammaRIII, E. coli triggers an inhibitory FcRgamma pathway that both impairs MARCO-mediated bacterial clearance and activates TNF-alpha secretion. 相似文献
89.
90.
Sanja?Nedic Steven?M.?Stufflebeam Carlo?Rondinoni Tonicarlo?R.?Velasco Antonio?C.?dos Santos Joao?P.?Leite Ana?C.?Gargaro Lilianne?R.?Mujica-ParodiEmail author Jaime?S.?IdeEmail author 《BMC neurology》2015,15(1):262