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排序方式: 共有101条查询结果,搜索用时 15 毫秒
71.
Bucardo F Nordgren J Carlsson B Paniagua M Lindgren PE Espinoza F Svensson L 《Journal of clinical microbiology》2008,46(8):2573-2580
Information about norovirus (NoV) infections in Central America is limited. Through a passive community and hospital pediatric diarrhea surveillance program, a total of 542 stool samples were collected between March 2005 and February 2006 in León, Nicaragua. NoV was detected in 12% (65/542) of the children; of these, 11% (45/409) were in the community and 15% (20/133) were in the hospital, with most strains (88%) belonging to genogroup II. NoV infections were age and gender associated, with children of <2 years of age (P < 0.05) and girls (P < 0.05) being most affected. Breast-feeding did not reduce the number of NoV infections. An important proportion (57%) of NoV-infected children were coinfected with diarrheagenic Escherichia coli. A significant proportion (18/31) of NoV-positive children with dehydration required intravenous rehydration. Nucleotide sequence analysis (38/65) of the N-terminal and shell region in the capsid gene revealed that at least six genotypes (GI.4, GII.2, GII.4, GII.7, GII.17, and a potentially novel cluster termed “GII.18-Nica”) circulated during the study period, with GII.4 virus being predominant (26/38). The majority (20/26) of those GII.4 strains shared high nucleotide homology (99%) with the globally emerging Hunter strain. The mean viral load was approximately 15-fold higher in children infected with GII.4 virus than in those infected with other G.II viruses, with the highest viral load observed for the group of children infected with GII.4 and requiring intravenous rehydration. This study, the first of its type from a Central American country, suggests that NoV is an important etiological agent of acute diarrhea among children of <2 years of age in Nicaragua. 相似文献
72.
Luciana Maria Silva Ana Cristina Carvalho Botelho Rafael Nacif-Pimenta Gustavo Ferreira Martins Luiz Carlos Alves Fabio André Brayner Consuelo Latorre Fortes-Dias Paulo Filemon Paolucci Pimenta 《Toxicon》2008,51(4):693-706
Spiders belonging to the genus Phoneutria (Perty, 1833), most commonly known as 'armed' spiders, are among the most dangerous species in Brazil due to high toxicity of their venom, associated with their habit of invading domestic or specific areas such as banana plantations. The venom of Phoneutria spiders is secreted by a pair of venom glands located inside their cephalothoraxes and connected to the chelicerae by two independent ducts. In the present study, the microanatomy and histological structure of the venom glands of Phoneutria nigriventer (Keyserling, 1891) were examined in detail by histochemical and conventional stains with laser confocal, scanning and transmission electron microscopies. The analysis confirmed the bulbous-shaped organ previously observed by others. The venom glands of P. nigriventer are covered externally by a double layer of striated muscles, which are arranged in a spiral fashion. This disposition of the external muscle fibers might provide the contraction movement of the venom gland to release their contents during a sting aggression. The presence of pore-like openings between the muscle fibers that cover the venom glands of P. nigriventer was considered quite remarkable. The presence of axon-like structures between the muscle fibers seen in the gland surface was also quite remarkable. The secretory epithelium of P. nigriventer invaginates into the gland lumen, contributing to the increase of the secretory surface area and also accommodating a higher number of secretory cells. Our observation of histological sections and SEM showed that the secretory cells in the venom gland of P. nigriventer form complex structures, secretory units, which originate at the base near the muscular layer and that extend into the central area until the gland lumen. Our study also identified a possible holocrine secretory mechanism of P. nigriventer venom gland, at least in the first venom milking, since we were able to see nuclei stained on confocal laser microscopy. However, our observation cannot disregard other possible types of secretory pathways in subsequent milkings, since we found no nuclei in the second and in the third venom secretions. 相似文献
73.
Historical trends in the production and consumption of illicit drugs in Mexico: implications for the prevention of blood borne infections 总被引:2,自引:0,他引:2
Bucardo J Brouwer KC Magis-Rodríguez C Ramos R Fraga M Perez SG Patterson TL Strathdee SA 《Drug and alcohol dependence》2005,79(3):281-293
Mexico has cultivated opium poppy since before the 1900's and has been an important transit route for South American cocaine for decades. However, only recently has drug use, particularly injection drug use, been documented as an important problem. Heroin is the most common drug used by Mexican injection drug users (IDUs). Increased cultivation of opium poppy in some Mexican states, lower prices for black tar heroin and increased security at U.S.-Mexican border crossings may be contributing factors to heroin use, especially in border cities. Risky practices among IDUs, including needle sharing and shooting gallery attendance are common, whereas perceived risk for acquiring blood borne infections is low. Although reported AIDS cases attributed to IDU in Mexico have been low, data from sentinel populations, such as pregnant women in the Mexican-U.S. border city of Tijuana, suggest an increase in HIV prevalence associated with drug use. Given widespread risk behaviors and rising numbers of blood borne infections among IDUs in Mexican-U.S. border cities, there is an urgent need for increased disease surveillance and culturally appropriate interventions to prevent potential epidemics of blood borne infections. We review available literature on the history of opium production in Mexico, recent trends in drug use and its implications, and the Mexican response, with special emphasis on the border cities of Ciudad Juarez and Tijuana. 相似文献
74.
Trends in production, trafficking, and consumption of methamphetamine and cocaine in Mexico 总被引:3,自引:0,他引:3
Brouwer KC Case P Ramos R Magis-Rodríguez C Bucardo J Patterson TL Strathdee SA 《Substance use & misuse》2006,41(5):707-727
Over the past decade, Mexico has experienced a significant increase in trafficking of cocaine and trafficking and production of methamphetamine. An estimated 70% of United States cocaine originating in South America passes through the Central America-Mexico corridor. Mexico-based groups are now believed to control 70%-90% of methamphetamine production and distribution in the United States. Increased availability of these drugs at reduced prices has led to a parallel rise in local drug consumption. Methamphetamine abuse is now the primary reason for seeking drug abuse treatment in a number of cities, primarily in northwestern Mexico. Although cocaine and methamphetamine use have been linked with the sex trade and high-risk behaviors, such as shooting gallery attendance and unprotected sex in other settings, comparatively little is known about the risk behaviors associated with use of these drugs in Mexico, especially for methamphetamines. We review historical aspects and current trends in cocaine and methamphetamine production, trafficking, and consumption in Mexico, with special emphasis on the border cities of Ciudad Juarez and Tijuana. Additionally, we discuss the potential public health consequences of cocaine use and the recent increase in methamphetamine use, especially in regards to the spread of bloodborne and other infections, in an effort to inform appropriate public health interventions. 相似文献
75.
Lisa C. Lindesmith Paul D. Brewer-Jensen Michael L. Mallory Mark R. Zweigart Samantha R. May Daniel Kelly Rachel Williams Sylvia Becker-Dreps Filemn Bucardo David J. Allen Judith Breuer Ralph S. Baric 《Viruses》2022,14(6)
Human norovirus is a leading cause of acute gastroenteritis, driven by antigenic variants within the GII.4 genotype. Antibody responses to GII.4 vaccination in adults are shaped by immune memory. How children without extensive immune memory will respond to GII.4 vaccination has not been reported. Here, we characterized the GII.4 neutralizing antibody (nAb) landscape following natural infection using a surrogate assay and antigenic site chimera virus-like particles. We demonstrate that the nAb landscape changes with age and virus exposure. Among sites A, C, and G, nAbs from first infections are focused on sites A and C. As immunity develops with age/exposure, site A is supplemented with antibodies that bridge site A to sites C and G. Cross-site nAbs continue to develop into adulthood, accompanied by an increase in nAb to site G. Continued exposure to GII.4 2012 Sydney correlated with a shift to co-dominance of sites A and G. Furthermore, site G nAbs correlated with the broadening of nAb titer across antigenically divergent variants. These data describe fundamental steps in the development of immunity to GII.4 over a lifetime, and illustrate how the antigenicity of one pandemic variant could influence the pandemic potential of another variant through the redirection of immunodominant epitopes. 相似文献
76.
77.
Rotavirus (RV) vaccination programs have been established in several countries using the human-attenuated G1P[8] monovalent vaccine Rotarix (GlaxoSmithKline) and/or the human-bovine reassortant G1, G2, G3, G4, P[8] pentavalent vaccine RotaTeq (Merck). The efficacy of both vaccines is high (~90%) in developed countries, but can be remarkably lower in developing countries. For example, a vaccine efficacy against severe diarrhea of only 58% was observed in a 2007-2009 Nicaraguan study using RotaTeq. To gain insight into the significant level of vaccine failure in this country, we sequenced the genomes of RVs recovered from vaccinated Nicaraguan children with gastroenteritis. The results revealed that all had genotype specificities typical for human RVs (11 G1P[8], 1 G3P[8]) and that the sequences and antigenic epitopes of the outer capsid proteins (VP4 and VP7) of these viruses were similar to those reported for RVs isolated elsewhere in the world. As expected, nine of the G1P[8] viruses and the single G3P[8] virus had genome constellations typical of human G1P[8] and G3P[8] RVs: G1/3-P[8]-I1-R1-C1-M1-A1-N1-T1-E1-H1. However, two of the G1P[8] viruses had atypical constellations, G1-P[8]-I1-R1-C1-M1-A1-N2-T1-E1-H1, due to the presence of a genotype-2 NSP2 (N2) gene. The sequence of the N2 NSP2 gene was identical to the bovine N2 NSP2 gene of RotaTeq, indicating that the two atypical viruses originated via reassortment of human G1P[8] RVs with RotaTeq viruses. Together, our data suggest that the high level of vaccine failure in Nicaraguan is probably not due to antigenic drift of commonly circulating virus strains nor the emergence of new antigenetically distinct virus strains. Furthermore, our data suggest that the widespread use of the RotaTeq vaccine has led to the introduction of vaccine genes into circulating human RVs. 相似文献
78.
Filemon Bucardo Elin Kindberg Margarita Paniagua Malin Vildevall Lennart Svensson 《Journal of medical virology》2009,81(4):728-735
Host genetic resistance to Norovirus (NoV) has been observed in challenge and outbreak studies in populations from Europe, Asia, and USA. In this study, we have investigated if histo‐blood group antigens can predict susceptibility to diarrhea caused by NoV in Nicaragua, Central America, and if this can be reflected in antibody‐prevalence and titer to NoV among individuals with different histo‐blood group antigen phenotypes. Investigation of 28 individuals infected with NoV and 131 population controls revealed 6% of non‐secretors in the population and nil non‐secretors among patients infected with NoV, suggesting that non‐secretors may be protected against NoV disease in Nicaragua. Surprisingly, 25% of the population was Lewis negative (Lea?b?). NoV infections with genogroup I (GI) and GII occurred irrespective of Lewis genotype, but none of the Lewis a positive (Lea + b?) were infected. The globally dominating GII.4 virus infected individuals of all blood groups except AB (n = 5), while the GI viruses (n = 4) infected only blood type O individuals. Furthermore, O blood types were susceptible to infections with GI.4, GII.4, GII.7, GII.17, and GII.18‐Nica viruses, suggesting that secretors with blood type O are susceptible (OR = 1.52) and non‐secretors resistant. The overall antibody‐prevalence to NoV GII.3 VLP was 62% with the highest prevalence among blood type B carriers (70%) followed by A (68%) and O (62%). All four investigated individuals carrying blood type AB were antibody‐negative. Among secretors, 63% were antibody‐positive compared to 33% among non‐secretors (P = 0.151). This study extends previous knowledge about the histo‐blood group antigens role in NoV disease in a population with different genetic background than North American and European. J. Med. Virol. 81:728–735, 2009 © 2009 Wiley‐Liss, Inc. 相似文献
79.
J Di Domizio S Dorta-Estremera M Gagea D Ganguly S Meller P Li B Zhao FK Tan L Bi M Gilliet W Cao 《Proceedings of the National Academy of Sciences of the United States of America》2012,109(36):14550-14555
The immunopathophysiologic development of systemic autoimmunity involves numerous factors through complex mechanisms that are not fully understood. In systemic lupus erythematosus, type I IFN (IFN-I) produced by plasmacytoid dendritic cells (pDCs) critically promotes the autoimmunity through its pleiotropic effects on immune cells. However, the host-derived factors that enable abnormal IFN-I production and initial immune tolerance breakdown are largely unknown. Previously, we found that amyloid precursor proteins form amyloid fibrils in the presence of nucleic acids. Here we report that nucleic acid-containing amyloid fibrils can potently activate pDCs and enable IFN-I production in response to self-DNA, self-RNA, and dead cell debris. pDCs can take up DNA-containing amyloid fibrils, which are retained in the early endosomes to activate TLR9, leading to high IFNα/β production. In mice treated with DNA-containing amyloid fibrils, a rapid IFN response correlated with pDC infiltration and activation. Immunization of nonautoimmune mice with DNA-containing amyloid fibrils induced antinuclear serology against a panel of self-antigens. The mice exhibited positive proteinuria and deposited antibodies in their kidneys. Intriguingly, pDC depletion obstructed IFN-I response and selectively abolished autoantibody generation. Our study reveals an innate immune function of nucleic acid-containing amyloid fibrils and provides a potential link between compromised protein homeostasis and autoimmunity via a pDC-IFN axis. 相似文献
80.
Tonya Cockrill Deborah J. del Junco Frank C. Arnett Shervin Assassi Filemon K. Tan Terry McNearney Michael Fischbach Marilyn Perry Maureen D. Mayes 《Arthritis care & research》2010,62(3):418-424