RESUMO
In the eastern Tibetan plateau both human cystic and alveolar echinococcosis (AE) caused by infection with Echincoccus granulosus or Echinococcus multilocularis, respectively are highly endemic. The domestic dog plays a key role in zoonotic transmission in this region. Our primary objective was to investigate the role of domestic dogs in maintaining transmission of E. multilocularis in Shiqu county, Sichuan. A cohort of 281 dogs was followed up over one year after a single treatment with praziquantel followed by re-infection surveillance at 2, 5 and 12 months post-treatment. Faecal samples were tested by an Echinococcus genus-specific coproantigen ELISA and two species-specific copro-PCR tests. Total Echinococcus coproantigen prevalence in Shiqu at baseline was 21% and 9·6% after 2 months. E. multilocularis copro-PCR was positive in 11·2% of dogs before treatment (vs 3·6% with E. granulosus copro-DNA), 2·9% at 2 months post-treatment, and 0% at 5 month and 12 months. The results suggest that dogs may have the potential to maintain E. multilocularis transmission within local pastoral communities, and thus dog dosing could be an effective strategy to reduce transmission of E. multilocularis as well as E. granulosus in these co-endemic Tibetan communities.
Assuntos
Antígenos de Helmintos/genética , Doenças do Cão/transmissão , Equinococose/transmissão , Equinococose/veterinária , Echinococcus granulosus/isolamento & purificação , Echinococcus multilocularis/isolamento & purificação , Monitoramento Epidemiológico/veterinária , Animais , Anti-Helmínticos/uso terapêutico , Vetores de Doenças , Doenças do Cão/tratamento farmacológico , Doenças do Cão/epidemiologia , Doenças do Cão/parasitologia , Cães , Equinococose/tratamento farmacológico , Equinococose/epidemiologia , Echinococcus granulosus/genética , Echinococcus multilocularis/genética , Ensaio de Imunoadsorção Enzimática , Fezes/parasitologia , Feminino , Humanos , Masculino , Contagem de Ovos de Parasitas , Reação em Cadeia da Polimerase , Praziquantel/uso terapêutico , Prevalência , Recidiva , Especificidade da Espécie , Tibet/epidemiologiaRESUMO
To identify genes required for mammalian spermatogenesis, we screened lines of mutant mice created using a retroviral gene-trap system for male infertility. Homozygous ROSA41 male mice exhibit sterility associated with progressive testicular degeneration. Germ-cell defects are first observed at 19 days post-natal (p19). Spermatogenesis is blocked during late spermiogenesis in young adults. Gradual depletion of all stages of germ cells results in a Sertoli-cell-only phenotype by approximately six months of age. Subsequently, almost all Sertoli cells are lost from the seminiferous tubules and the Leydig cell population is reduced. Molecular analysis indicates that the gene mutated is Bclw, a death-protecting member of the Bcl2 family. The mutant allele of Bclw in ROSA41 does not produce a Bclw polypeptide. Expression of Bclw in the testis appears to be restricted to elongating spermatids and Sertoli cells. Potential roles for Bclw in testicular function are discussed.
Assuntos
Proteínas/genética , Proteínas/metabolismo , Espermatozoides/crescimento & desenvolvimento , Testículo/patologia , Testículo/fisiologia , Fatores Etários , Sequência de Aminoácidos , Animais , Proteínas Reguladoras de Apoptose , Clonagem Molecular , Hormônio Foliculoestimulante/sangue , Homozigoto , Imuno-Histoquímica , Infertilidade Masculina/genética , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos , Camundongos Mutantes , Microscopia Eletrônica , Dados de Sequência Molecular , Provírus/genética , Técnica de Amplificação ao Acaso de DNA Polimórfico , Análise de Sequência , Células de Sertoli/metabolismo , Espermatozoides/patologia , Distribuição TecidualRESUMO
[This corrects the article DOI: 10.1177/20458940211053196.].
RESUMO
In the past few years, there has been remarkable progress unraveling the mechanism and significance of eukaryotic programmed cell death (PCD), or apoptosis. Not surprisingly, it has been discovered that numerous, unrelated microbial pathogens engage or circumvent the host's apoptotic program. In this chapter, we briefly summarize apoptosis, emphasizing those studies which assist the reader in understanding the subsequent discussion on PCD and pathogens. We then examine the relationship between virulent bacteria and apoptosis. This section is organized to reflect both common and diverse mechanisms employed by bacteria to induce PCD. A short discussion of parasites and fungi is followed by a detailed description of the interaction of viral pathogens with the apoptotic machinery. Throughout the review, apoptosis is considered within the broader contexts of pathogenesis, virulence, and host defense. Our goals are to update the reader on this rapidly expanding field and identify topics in the current literature which demand further investigation.
Assuntos
Apoptose/fisiologia , Animais , Fenômenos Fisiológicos Bacterianos , Fungos/fisiologia , Humanos , Parasitos/fisiologiaRESUMO
The cytochrome P450-dependent monooxygenases play a central role in the metabolism of chemical carcinogens. The action of these enzymes can lead to either carcinogen detoxication or activation. Differences in P450 expression in animal models give rise to large differences in susceptibility to chemical carcinogens, so genetic polymorphisms in P450 expression may be expected to be an important factor in individual human susceptibility to cancer. Of particular interest is the genetic polymorphism at the cytochrome P450-debrisoquine/sparteine hydroxylase locus (CYP2D6). Although this is a minor liver P450, its polymorphic expression is associated with the abnormal metabolism of at least 30 therapeutic drugs, including beta-blockers and tricyclic antidepressants. Conflicting reports have been made on the association of this polymorphism with cancer susceptibility. This disagreement may be attributable to limitations of the phenotyping assay used to identify affected individuals (poor metabolizers, PMs). In order to clarify these anomalies, we have developed a simple DNA-based assay with which we can identify the majority of PMs. The assay is centered around the primary gene defect responsible for the polymorphism, a G to A transition at the junction of intron 3/exon 4 which results in a frame-shift in the resultant mRNA. The frequency of this mutation is 70-80% in PMs. We have studied the frequency of mutated alleles in a control population and in a wide range of cancer patients. No association between this polymorphism and lung cancer susceptibility was observed; however, in other populations of cancer patients some very interesting shifts were found in the proportion of PMs and heterozygotes from that in the normal population.
Assuntos
Sistema Enzimático do Citocromo P-450/genética , Oxigenases de Função Mista/genética , Neoplasias/genética , Sequência de Bases , Citocromo P-450 CYP2D6 , Sistema Enzimático do Citocromo P-450/metabolismo , Análise Mutacional de DNA , Suscetibilidade a Doenças , Humanos , Oxigenases de Função Mista/metabolismo , Dados de Sequência Molecular , Neoplasias/enzimologia , Reação em Cadeia da Polimerase , Polimorfismo GenéticoRESUMO
Drug-induced paralysis in the mechanically ventilated neonate is prescribed primarily to control breathing and, secondarily, to favorably affect underlying pulmonary disease and associated complications. Although the control of breathing can be achieved, it is controversial when pulmonary disease is favorably influenced by paralysis. However, such therapy may lessen the severity, and the incidence of the complications in specific subgroups of infants. In view of significant adverse effects, muscle paralysis should be used judiciously in neonates.
Assuntos
Fármacos Neuromusculares não Despolarizantes/uso terapêutico , Paralisia/induzido quimicamente , Respiração Artificial , Humanos , Recém-Nascido , Fármacos Neuromusculares não Despolarizantes/efeitos adversos , Fármacos Neuromusculares não Despolarizantes/farmacologiaRESUMO
Probes for cytochrome P450IVA (P450IVA), alpha- and pi-class glutathione S-transferases (GST), and phenol-metabolizing UDP-glucuronyltransferase (UDPGT-K39) detected restriction fragment length variants (RFLVs) between C57BL/6J and DBA/2J mice. These variants were used to map the P450IVA genes (Cyp4 alpha) to chromosome 4, close to Mtv-13 and Pmv-19, midway between brown (b) and Gpd-1; GST alpha genes were mapped to chromosome 9, with a cross-hybridizing sequence mapping to another chromosome; the GST pi genes were mapped to the distal end of chromosome 1 near Pmv-21; one UDPGT-K39 variant to chromosome 1, between Acrg and Emv-17, and another showed linkage to Odc-10 on an unidentified chromosome. No RFLVs were detected with probes for P450IID, P450 reductase, androsterone-metabolizing UDPGT, GST mu, or microsomal GST.
Assuntos
Mapeamento Cromossômico , Sistema Enzimático do Citocromo P-450/genética , Glucuronosiltransferase/genética , Glutationa Transferase/genética , Camundongos Endogâmicos/genética , Animais , Sondas de DNA , Humanos , Camundongos , Família Multigênica , Polimorfismo de Fragmento de Restrição , RatosRESUMO
The cytochrome P450IIB gene subfamily (Cyp2b) has previously been mapped close to the Coh locus encoding a cytochrome P450 with coumarin 7-hydroxylase (COH) activity on mouse chromosome 7. Given this observation, it had been considered that COH was a member of the P450IIB subfamily. However, recent biochemical and cDNA expression experiments indicate that a member of the P450IIA subfamily, rather than of the P450IIB subfamily, encodes COH. We have resolved this apparent anomaly between the genetic and biochemical data by showing that genes from the P450IIA subfamily (Cyp2a) are closely linked to Coh and to Cyp2b on mouse chromosome 7.
Assuntos
Hidrocarboneto de Aril Hidroxilases , Cromossomos , Sistema Enzimático do Citocromo P-450/genética , Ligação Genética , Oxigenases de Função Mista/genética , Família Multigênica , Animais , Citocromo P-450 CYP2A6 , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos DBA , Oxigenases de Função Mista/metabolismo , Polimorfismo de Fragmento de RestriçãoRESUMO
The PhoP/PhoQ two-component regulatory system controls transcription of several key virulence genes essential for Salmonella survival in the host cell phagosome. Here, we determine that the PhoP/PhoQ system also regulates virulence in the aetiological agent of bacillary dysentery, Shigella flexneri, even though this pathogen escapes from the phagosome into the cytoplasm of the host cell. A phoP mutant of Shigella established infections and induced an acute inflammatory response in two different animal models. However, infections with phoP mutant bacteria were resolved more rapidly than infections with wild-type Shigella. Moreover, the Shigella phoP mutant was more sensitive than the wild-type strain to killing by polymorphonuclear leucocytes (PMNs), cationic polypeptides extracted from PMNs and other animal-derived antimicrobial peptides. The phoP mutant, however, invaded epithelial cells, spread intercellularly, induced apoptosis in macrophages and tolerated extreme acid pH as efficiently as the wild-type strain. PhoP appears to regulate Shigella susceptibility to PMNs and antimicrobial molecules that are important for the late stages of infection with this enteric bacterium.
Assuntos
Proteínas de Bactérias/metabolismo , Disenteria Bacilar/microbiologia , Regulação Bacteriana da Expressão Gênica , Inflamação/imunologia , Shigella flexneri/patogenicidade , Animais , Proteínas de Bactérias/genética , Proteínas de Bactérias/farmacologia , Infecções por Enterobacteriaceae/imunologia , Infecções por Enterobacteriaceae/microbiologia , Células HeLa , Humanos , Concentração de Íons de Hidrogênio , Ceratoconjuntivite/imunologia , Ceratoconjuntivite/microbiologia , Pulmão/imunologia , Pulmão/microbiologia , Macrófagos/microbiologia , Camundongos , Neutrófilos/imunologia , Transdução de Sinais , Virulência/genéticaRESUMO
Pathogenicity islands are chromosomal gene clusters, often located adjacent to tRNA genes, that encode virulence factors present in pathogenic organisms but absent or sporadically found in related non-pathogenic species. The selC tRNA locus is the site of integration of different pathogenicity islands in uropathogenic Escherichia coli, enterohaemorrhagic E. coli and Salmonella enterica. We show here that the selC locus of Shigella flexneri, the aetiological agent of bacterial dysentery, also contains a pathogenicity island. This pathogenicity island, designated SHI-2 (Shigella island 2), occupies 23.8 kb downstream of selC and contains genes encoding the aerobactin iron acquisition siderophore system, colicin V immunity and several novel proteins. Remnants of multiple mobile genetic elements are present in SHI-2. SHI-2-hybridizing sequences were detected in all S. flexneri strains tested and parts of the island were also found in other Shigella species. SHI-2 may allow Shigella survival in stressful environments, such as those encountered during infection.
Assuntos
Proteínas de Bactérias/genética , Cromossomos Bacterianos/genética , Colicinas , Genes Bacterianos , Shigella flexneri/genética , Mapeamento Cromossômico , Clonagem Molecular , Elementos de DNA Transponíveis/genética , DNA Bacteriano/genética , Enterobacteriaceae/genética , Escherichia coli/genética , Ácidos Hidroxâmicos/metabolismo , Integrases/genética , Óperon , Alinhamento de Sequência , Homologia de Sequência do Ácido Nucleico , Shigella flexneri/patogenicidade , Especificidade da Espécie , Transposases/genética , Virulência/genéticaRESUMO
A strategy based on the gene trap was developed to prescreen mouse embryonic stem cells for insertional mutations in genes encoding secreted and membrane-spanning proteins. The "secretory trap" relies on capturing the N-terminal signal sequence of an endogenous gene to generate an active beta-galactosidase fusion protein. Insertions were found in a cadherin gene, an unc6-related laminin (netrin) gene, the sek receptor tyrosine kinase gene, and genes encoding two receptor-linked protein-tyrosine phosphatases, LAR and PTP kappa. Analysis of homozygous mice carrying insertions in LAR and PTP kappa showed that both genes were effectively disrupted, but neither was essential for normal embryonic development.
Assuntos
Desenvolvimento Embrionário e Fetal , Células-Tronco/fisiologia , Animais , Sequência de Bases , Caderinas/biossíntese , Linhagem Celular , Clonagem Molecular , Cricetinae , Primers do DNA , Embrião de Mamíferos , Proteínas Fetais/biossíntese , Rim , Laminina/biossíntese , Camundongos , Dados de Sequência Molecular , Mutagênese Insercional , Oligodesoxirribonucleotídeos , Reação em Cadeia da Polimerase , Proteínas Tirosina Fosfatases/biossíntese , Proteínas Tirosina Quinases/biossíntese , Receptores Proteína Tirosina Quinases/biossíntese , Receptor EphA4 , Proteínas Recombinantes de Fusão/biossíntese , Células-Tronco/citologia , Transfecção , beta-Galactosidase/biossínteseRESUMO
We report here that the Shigella invasion plasmid antigen (Ipa)B, which is sufficient to induce apoptosis in macrophages, binds to caspase (Casp)-1, but not to Casp-2 or Casp-3. Casp-1 is activated and its specific substrate interleukin-1beta is cleaved shortly after Shigella infection. Macrophages isolated from Casp-1 knock-out mice are not susceptible to Shigella-induced apoptosis, although they respond normally to other apoptotic stimuli. Shigella kills macrophages from casp-3, casp-11, and p53 knock-out mice as well as macrophages overexpressing Bcl-2. We propose that Shigella induces apoptosis by directly activating Casp-1 through IpaB, bypassing signal transduction events and caspases upstream of Casp-1. Taken together these data indicate that Shigella-induced apoptosis is distinct from other forms of apoptosis and seems uniquely dependent on Casp-1.
Assuntos
Apoptose , Proteínas de Bactérias/metabolismo , Caspase 1/metabolismo , Shigella/fisiologia , Animais , Caspase 1/genética , Macrófagos Peritoneais/enzimologia , Macrófagos Peritoneais/microbiologia , Camundongos , Camundongos Knockout , Ligação Proteica , Proteínas Proto-Oncogênicas c-bcl-2/fisiologia , Proteína Supressora de Tumor p53/fisiologiaRESUMO
The mammalian cytochrome P450-dependent monooxygenase system is involved in the metabolism of drugs and chemical carcinogens. The role of these enzymes in toxicological response is exemplified by an autosomal recessive polymorphism at the cytochrome P450 CYP2D6 debrisoquine hydroxylase locus which results in the severely compromised metabolism of at least 25 drugs, and which in some cases can lead to life-threatening side-effects. In addition, this polymorphism, which affects 8-10% of the caucasian population, has been associated with altered susceptibility to lung and bladder cancer. Here we report the identification of the primary mutation responsible for this metabolic defect and the development of a simple DNA-based genetic assay to allow both the identification of most individuals at risk of drug side-effects and clarification of the conflicting reports on the association of this polymorphism with cancer susceptibility.
Assuntos
Sistema Enzimático do Citocromo P-450/genética , Oxigenases de Função Mista/genética , Mutação , Sequência de Bases , Citocromo P-450 CYP2D6 , Desoxirribonucleases de Sítio Específico do Tipo II , Humanos , Neoplasias Pulmonares/genética , Dados de Sequência Molecular , Fenótipo , Reação em Cadeia da Polimerase , Polimorfismo de Fragmento de Restrição , Neoplasias da Bexiga Urinária/genéticaRESUMO
Glutathione-dependent enzymes play a central role in the protection of cells from cytotoxic chemicals and have been implicated in the intrinsic and acquired resistance of tumors to cytotoxic drugs. We have generated a Chinese hamster ovary line resistant to bifunctional nitrogen mustards and in this report have characterized and isolated the protein that represents the major observable phenotypic difference between the drug-sensitive and drug-resistant cell lines. This purified protein is shown to be an alpha class glutathione S-transferase comprising YcYc subunits and possessing a pI value of approximately 8.0. The intracellular level of the Yc subunit is elevated greater than 40-fold in the drug-resistant cell line, which could account for the increase in glutathione S-transferase (RX:glutathione R-transferase; EC 2.5.1.18) activity toward both 1-chloro-2,4-dinitrobenzene and cumene hydroperoxide. Other glutathione S-transferase subunits within this gene family are also elevated. These changes are accompanied by a significant elevation in alpha class mRNA levels. Southern analysis indicates that the genes coding for these proteins are amplified 4- to 8-fold in the drug-resistant cell line. In addition, gamma-glutamyl transpeptidase [(5-glutamyl)-peptide:amino acid 5-glutamyltransferase; EC 2.3.2.2] activity is increased 3.6-fold in the drug-resistant Chinese hamster ovary cell line, which may explain the increase in cellular glutathione level. In this case no gene amplification was seen. These data indicate that gene amplification may be important in drug resistance toward alkylating agents and also that other enzymes in glutathione homeostasis are involved.
Assuntos
Amplificação de Genes , Genes , Glutationa Transferase/genética , Compostos de Mostarda Nitrogenada/farmacologia , Animais , Western Blotting , Linhagem Celular , Resistência a Medicamentos/genética , Glutationa Transferase/isolamento & purificação , Glutationa Transferase/metabolismoRESUMO
There have been a series of reports on the association of a genetic polymorphism at the cytochrome P450 CYP2D6 gene locus with cancer susceptibility. Many of these reports have remained contradictory either because of small numbers of patients studied or because of the limitations and controversy surrounding the pharmacokinetic assay used to identify affected individuals (poor metabolizers; PMs). We have recently developed a DNA-based assay that will allow the unequivocal identification of poor metabolizers and have applied this to the study of 1635 patients with different forms of cancer. Out of 361 lung cancer patients studied no statistically significant change in the proportion of PMs relative to controls was found. However, a significant increase in the proportion of poor metabolizers or heterozygotes was seen in leukaemia, bladder cancer and melanoma patients. This could be explained by a role for CYP2D6 in carcinogen detoxification or by linkage to another cancer-causing gene.