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1.
J Food Prot ; 76(10): 1810-6, 2013 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-24112586

RESUMO

Infectious acute gastroenteritis (AGE) is a major health problem worldwide. Salmonella is a leading cause of AGE outbreaks, but viruses may be responsible for up to 80% of cases. We compared the frequency and characteristics of AGE out breaks in Catalonia due to norovirus and Salmonella and the changes in these outbreaks from 2000 through 2010. In 2006 through 2010, we also investigated the distribution by season, setting, and implicated food, the incidence rates of cases associated, and the hospitalization rates. Differences in proportions were estimated by Pearson's chi-square test, and the odds ratio (OR) and 95% confidence interval (CI) were calculated. In 2000 through 2010, the number of AGE outbreaks caused by Salmonella decreased and those caused by norovirus significantly increased. From 2006 onward, norovirus was the most common etiology in AGE outbreaks, but in foodborne outbreaks, Salmonella was the more common cause until 2010. The incidence rate per 10(5) inhabitants was greater for norovirus (20.81 versus 3.97, P < 0.001), and the hospitalization rate was lower for norovirus (0.84 versus 4.69, P < 0.001). Salmonella infections occurred more frequently in the warmer months, and norovirus infections were more common in the colder months, both in terms of total outbreaks (OR = 4.50; 95% CI, 2.85 to 7.11; P < 0.001) and foodborne outbreaks (OR = 4.38; 95% CI, 2.42 to 7.95; P < 0.001). Norovirus infections were less common in private homes (OR = 0.08; 95% CI, 0.04 to 0.14; P < 0.001) and more common in nursing homes (P < 0.001) and hospitals or long-term care facilities (OR = 14.09; 95% CI, 3.35 to 59.33; P < 0.001). Foods most frequently implicated in norovirus infection outbreaks were seafood (22% ; OR = 7.89; 95% CI, 2.59 to 24.3; P < 0.001), and those most common in Salmonella infection outbreaks were mayonnaise and similar items (30.2%; OR = 0.05; 95% CI, 0.01 to 0.22; P < 0.001). Foodborne outbreaks in which the vehicle was not identified were more frequent in cases of norovirus infection (OR = 4.59; 95% CI, 2.54 to 8.30; P < 0.001). Our results indicate that norovirus rather than Salmonella is the most common cause of AGE outbreaks in Catalonia. Foodborne AGE outbreaks were more commonly caused by norovirus than by Salmonella only in 2010, the last year of the study.


Assuntos
Infecções por Caliciviridae/epidemiologia , Gastroenterite/epidemiologia , Norovirus/isolamento & purificação , Intoxicação Alimentar por Salmonella/epidemiologia , Doença Aguda , Adulto , Infecções por Caliciviridae/transmissão , Pré-Escolar , Infecção Hospitalar , Surtos de Doenças , Gastroenterite/microbiologia , Gastroenterite/virologia , Hospitalização , Hospitais , Humanos , Masculino , Norovirus/patogenicidade , Casas de Saúde , Salmonella/isolamento & purificação , Salmonella/patogenicidade , Intoxicação Alimentar por Salmonella/transmissão , Estações do Ano , Espanha/epidemiologia
2.
Microbiology (Reading) ; 159(Pt 12): 2663-2673, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24085836

RESUMO

Cytoplasmic membranes of the strictly anaerobic sulfate-reducing bacterium Desulfovibrio vulgaris Hildenborough contain two terminal oxygen reductases, a bd quinol oxidase and a cc(b/o)o3 cytochrome oxidase (Cox). Viability assays pointed out that single Δbd, Δcox and double ΔbdΔcox deletion mutant strains were more sensitive to oxygen exposure than the WT strain, showing the involvement of these oxygen reductases in the detoxification of oxygen. The Δcox strain was slightly more sensitive than the Δbd strain, pointing to the importance of the cc(b/o)o3 cytochrome oxidase in oxygen protection. Decreased O2 reduction rates were measured in mutant cells and membranes using lactate, NADH, ubiquinol and menadiol as substrates. The affinity for oxygen measured with the bd quinol oxidase (Km, 300 nM) was higher than that of the cc(b/o)o3 cytochrome oxidase (Km, 620 nM). The total membrane activity of the bd quinol oxidase was higher than that of the cytochrome oxidase activity in line with the higher expression of the bd oxidase genes. In addition, analysis of the ΔbdΔcox mutant strain indicated the presence of at least one O2-scavenging membrane-bound system able to reduce O2 with menaquinol as electron donor with an O2 affinity that was two orders of magnitude lower than that of the bd quinol oxidase. The lower O2 reductase activity in mutant cells with hydrogen as electron donor and the use of specific inhibitors indicated an electron transfer link between periplasmic H2 oxidation and membrane-bound oxygen reduction via the menaquinol pool. This linkage is crucial in defence of the strictly anaerobic bacterium Desulfovibrio against oxygen stress.


Assuntos
Desulfovibrio vulgaris/metabolismo , Hidrogênio/metabolismo , Proteínas de Membrana/metabolismo , Oxirredutases/metabolismo , Oxigênio/metabolismo , Periplasma/metabolismo , Sulfatos/metabolismo , Anaerobiose , Desulfovibrio vulgaris/enzimologia , Transporte de Elétrons , Deleção de Genes , Proteínas de Membrana/genética , Viabilidade Microbiana , Oxirredução , Oxirredutases/genética , Periplasma/enzimologia
3.
Rev Esp Enferm Dig ; 103(1): 5-12, 2011 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-21341931

RESUMO

OBJECTIVE: Analysis and evaluation of a multidisciplinary approach, postoperative results and survival of a group of patients with resected pancreatic cancer after a multimodal therapy. DESIGN: DESCRIPTIVE, prospective and observational study. PATIENTS: Between January 2004 and December 2004, 124 patients with pancreatic cancer were evaluated. In 30 patients pancreatic resection was performed, and they are the object of this study. Results of preoperative evaluation, postoperative morbidity and mortality, and long term survival were studied. RESULTS: Diagnostic evaluation was completed in ambulatory basis in 20% of the patients. In 63% of cases, admission was done in the same day of surgery. In 3 patients (9%), tumor resection was not achieved, therefore, concordance between radiological and surgical resectability rate was 91%. Resectability rate was 24.1%. Surgical Mortality was 3.3%, with a global morbidity rate of 56.6%. Survival at one, two, three and, four years was 76.2%, 56.3%, 43%, y 27.3% respectively. CONCLUSIONS: Technological development and coordination of efforts in multidisciplinary teams offer an accurate evaluation of tumor involvement, and may reduce the number of laparotomies without tumor resection. The application of a systematic and generalized multimodal treatment in pancreatic cancer is progressively showing a tendency of progressive increase in resectability and survival rates in pancreatic cancer.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Carcinoma Ductal Pancreático/terapia , Pancreatectomia/métodos , Neoplasias Pancreáticas/terapia , Equipe de Assistência ao Paciente , Adulto , Idoso , Idoso de 80 Anos ou mais , Carcinoma/diagnóstico , Carcinoma/diagnóstico por imagem , Carcinoma/patologia , Carcinoma/terapia , Carcinoma Ductal Pancreático/diagnóstico , Carcinoma Ductal Pancreático/diagnóstico por imagem , Carcinoma Ductal Pancreático/patologia , Carcinoma Ductal Pancreático/secundário , Quimioterapia Adjuvante , Colangiopancreatografia Retrógrada Endoscópica , Colectomia , Terapia Combinada , Desoxicitidina/administração & dosagem , Desoxicitidina/análogos & derivados , Diagnóstico por Imagem , Feminino , Hepatectomia/métodos , Humanos , Estimativa de Kaplan-Meier , Neoplasias Hepáticas/secundário , Neoplasias Hepáticas/cirurgia , Masculino , Pessoa de Meia-Idade , Terapia Neoadjuvante , Compostos Organoplatínicos/administração & dosagem , Oxaliplatina , Pancreatectomia/mortalidade , Neoplasias Pancreáticas/diagnóstico , Neoplasias Pancreáticas/diagnóstico por imagem , Neoplasias Pancreáticas/patologia , Pancreaticoduodenectomia , Estudos Prospectivos , Stents , Taxa de Sobrevida , Gencitabina
4.
Rev. esp. enferm. dig ; 103(1): 5-12, ene. 2011. tab, ilus
Artigo em Espanhol | IBECS | ID: ibc-84891

RESUMO

Objetivo: analizar la evaluación del abordaje multidisciplinario de un grupo de pacientes con cáncer de páncreas resecado, los resultados postoperatorios y la supervivencia tras la aplicación de un tratamiento multimodal. Diseño: estudio descriptivo prospectivo observacional. Pacientes: entre enero de 2004 y diciembre 2009 se evaluaron 124 pacientes con cáncer de páncreas. De ellos, se realizó la resección pancreática con intención curativa en 30 casos que constituyen el objeto del estudio. Se analizaron los resultados del estudio preoperatorio de extensión tumoral, la morbi-mortalidad postoperatoria, y la supervivencia. Resultados: la evaluación diagnóstica se hizo en régimen ambulatorio en el 20% de los pacientes. En el 63% de los casos, el ingreso fue el mismo día de la intervención. En 3 pacientes intervenidos no se consiguió realizar la resección del tumor (9%), por lo que la tasa de concordancia entre la resecabilidad radiológica y la quirúrgica fue del 91%. La tasa de resecabilidad quirúrgica fue del 24,1%. La mortalidad quirúrgica de la serie fue de un 3,3%, con una morbilidad global del 56,6%. La supervivencia al año, dos, tres y cuatro años fue del 76,2%, 56,3%, 43%, y 27,3% respectivamente. Conclusiones: el desarrollo tecnológico y la evaluación multidisciplinar coordinada, permite realizar una evaluación precisa de la extensión tumoral, y puede reducir el número de laparotomías sin resección del tumor. Con la aplicación de una terapia multimodal sistemática combinada, la resecabilidad quirúrgica y la supervivencia a medio y largo plazo parece que están aumentando de forma progresiva(AU)


Objective: analysis and evaluation of a multidisciplinary approach, postoperative results and survival of a group of patients with resected pancreatic cancer after a multimodal therapy. Design: descriptive, prospective and observational study. Patients: between January 2004 and December 2004, 124 patients with pancreatic cancer were evaluated. In 30 patients pancreatic resection was performed, and they are the object of this study. Results of preoperative evaluation, postoperative morbidity and mortality, and long term survival were studied. Results: diagnostic evaluation was completed in ambulatory basis in 20% of the patients. In 63% of cases, admission was done in the same day of surgery. In 3 patients (9%), tumor resection was not achieved, therefore, concordance between radiological and surgical resectability rate was 91%. Resectability rate was 24.1%. Surgical Mortality was 3.3%, with a global morbidity rate of 56.6%. Survival at one, two, three and, four years was 76.2%, 56.3%, 43%, y 27.3% respectively. Conclusions: technological development and coordination of efforts in multidisciplinary teams offer an accurate evaluation of tumor involvement, and may reduce the number of laparotomies without tumor resection. The application of a systematic and generalized multimodal treatment in pancreatic cancer is progressively showing a tendency of progressive increase in resectability and survival rates in pancreatic cancer(AU)


Assuntos
Humanos , Masculino , Feminino , Adulto , Pessoa de Meia-Idade , Idoso , Idoso de 80 Anos ou mais , Terapia Combinada/tendências , Terapia Combinada , Sinais e Sintomas , Neoplasias Pancreáticas/diagnóstico , Neoplasias Pancreáticas/terapia , /tendências , Excisão de Linfonodo , Adjuvantes Farmacêuticos/uso terapêutico , Pancreatectomia/métodos , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Indicadores de Morbimortalidade , Cuidados Pós-Operatórios/tendências , Fístula/terapia , Pancreatectomia/tendências , Pancreatectomia
5.
J Med Case Rep ; 2: 25, 2008 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-18226219

RESUMO

INTRODUCTION: Autoimmune hepatitis is a necroinflammatory disorder of unknown etiology characterized by the presence of circulating antibodies, hypergammaglobulinemia, and response to immunosuppression. It has the histological features of chronic hepatitis. The onset is usually insidious, but in some patients the presentation may be acute and occasionally severe. Certain drugs can induce chronic hepatitis mimicking autoimmune hepatitis. Different autoantibodies have been associated with this process but they are not detectable after drug withdrawal and clinical resolution. CASE PRESENTATION: We describe a case of drug-induced acute hepatitis associated with antinuclear, antisoluble liver-pancreas and anti-smooth muscle autoantibodies in a 66-year-old woman. Abnormal clinical and biochemical parameters resolved after drug withdrawal, but six months later anti-soluble liver-pancreas antibodies remained positive and liver biopsy showed chronic hepatitis and septal fibrosis. Furthermore, our patient has a HLA genotype associated with autoimmune hepatitis. CONCLUSION: Patient follow-up will disclose whether our patient suffers from an autoimmune disease and if the presence of anti-soluble liver antigens could precede the development of an autoimmune hepatitis, as the presence of antimitochondrial antibodies can precede primary biliary cirrhosis.

6.
Epidemiol Infect ; 133(5): 817-22, 2005 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-16181500

RESUMO

A large outbreak of gastroenteritis occurred in Catalonia in June 2002 with 1435 cases and 117 hospitalizations. Consumption of a hard pastry with vanilla cream was strongly associated with illness. Stool samples from cases and food-handlers were analysed. The premises of the food manufacturer were inspected and food samples were taken for microbiological analysis. Salmonella serotype Enteriditis was isolated from 154 cases, three food-handlers and nine food samples. Outbreak-associated strains showed a coincident phage type, antibiotype and pulse-field gel electrophoresis pattern. Inadequate handling of foods containing eggs occurred because the establishment exceeded its safe food production capacity to meet demand for the pastry, which was consumed on the day of a traditional festival. Excessive production of foods for holidays or special events represents a potential public health threat.


Assuntos
Surtos de Doenças , Microbiologia de Alimentos , Intoxicação Alimentar por Salmonella/epidemiologia , Salmonella enteritidis/isolamento & purificação , Adolescente , Adulto , Estudos de Casos e Controles , Criança , Pré-Escolar , Laticínios/microbiologia , Fezes/microbiologia , Feminino , Manipulação de Alimentos , Férias e Feriados , Humanos , Lactente , Masculino , Pessoa de Meia-Idade , Intoxicação Alimentar por Salmonella/microbiologia , Salmonella enteritidis/classificação , Espanha/epidemiologia
7.
Gastroenterol Hepatol ; 28(4): 228-31, 2005 Apr.
Artigo em Espanhol | MEDLINE | ID: mdl-15811265

RESUMO

Diaphragm disease (DD) induced by non-steroidal anti-inflammatory drugs (NSAIDs) and neuromuscular and vascular hamartoma (NMVH) are rare entities that can be difficult to recognize clinically, radiologically and pathologically. Both may cause small bowel obstruction and both reveal annular constrictions macroscopically. However, the 2 entities differ in that the constrictions are purely fibrous in DD whereas they have a hamartomatous histopathology in NMVH. We describe the case of a 76-year-old woman with a history of prolonged NSAID use who developed clinical features and gross pathology consistent with DD and histopathology of NMVH.


Assuntos
Anti-Inflamatórios não Esteroides/efeitos adversos , Hamartoma/induzido quimicamente , Doenças do Íleo/induzido quimicamente , Obstrução Intestinal/etiologia , Idoso , Feminino , Hamartoma/patologia , Humanos , Doenças do Íleo/patologia
8.
Gastroenterol. hepatol. (Ed. impr.) ; 28(4): 228-231, abr. 2005. ilus, tab
Artigo em Es | IBECS | ID: ibc-036361

RESUMO

La enfermedad diafragmática intestinal (EDI) asociada a los antiinflamatorios no esteroideos (AINE) y el hamartoma neuromuscular y vascular (HNMV) son 2 entidades raras, de difícil diagnóstico clínico, radiológico y patológico. Ambas pueden ser causa de obstrucción intestinal y macroscópicamente pueden evidenciarse en forma de estenosis intestinales de tipo anular. Sin embargo, difieren en su histología: en la EDI las estenosis son fibrosas y en el HNMV son hamartomatosas. Presentamos el caso de una mujer de 76 años con antecedentes de ingesta prolongada de AINE por artropatía que presentóclínica y macroscopia compatibles con EDI e histología propia del HNMV


Diaphragm disease (DD) induced by non-steroidal anti-inflammatory drugs (NSAIDs) and neuromuscular and vascularhamartoma (NMVH) are rare entities that can be difficult to recognize clinically, radiologically and pathologically.Both may cause small bowel obstruction and both reveal anular constrictions macroscopically. However, the 2 entities differ in that the constrictions are purely fibrous in DD whereas they have a hamartomatous histopathology in NMVH. We describe the case of a 76-year-old woman with a history of prolonged NSAID use who developed clinical features and gross pathology consistent with DD and histopathology of NMVH


Assuntos
Feminino , Idoso , Humanos , Anti-Inflamatórios não Esteroides/efeitos adversos , Hamartoma/induzido quimicamente , Obstrução Intestinal/etiologia , Doenças do Íleo/induzido quimicamente , Hamartoma/patologia , Doenças do Íleo/patologia
9.
Clín. investig. ginecol. obstet. (Ed. impr.) ; 31(10): 362-365, dic. 2004. ilus
Artigo em Es | IBECS | ID: ibc-36684

RESUMO

El miofibroblastoma intranodular es una tumoración primaria de ganglio linfático, infrecuente y de comportamiento benigno. En un principio se pensó que sólo se asentaba en los ganglios linfáticos inguinales, pero posteriormente fue descrito en localizaciones extrainguinales. El diagnóstico diferencial debe realizarse con otras neoplasias mesenquimales y con posibles metástasis de melanomas, sarcomas o carcinomas fusocelulares. Presentamos el caso de una mujer de 41 años portadora de una tumoración en la región axilar derecha que fue diagnosticada por punción-aspiración con aguja fina como neoplasia mesenquimal benigna y posteriormente, con la biopsia, como miofibroblastoma (AU)


Assuntos
Adulto , Feminino , Humanos , Gânglios/patologia , Gânglios/citologia , Mitose , Condrossarcoma Mesenquimal/complicações , Condrossarcoma Mesenquimal/diagnóstico , Neoplasias de Tecido Muscular/complicações , Neoplasias de Tecido Muscular/diagnóstico , Neoplasias Primárias Desconhecidas/complicações , Biópsia por Agulha , Diagnóstico Diferencial , Axila/patologia , Metástase Neoplásica/fisiopatologia , Neoplasias de Tecido Muscular/complicações , Neoplasias de Tecido Muscular/diagnóstico
10.
Eur J Clin Microbiol Infect Dis ; 21(10): 717-21, 2002 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-12415470

RESUMO

As part of a case-control study of community-acquired Legionnaires' disease, several factors related to residential water distribution systems and public drinking water systems were studied in the homes of 124 patients with community-acquired Legionnaire's disease and in the homes of 354 controls. The presence of water reservoirs and hot water tanks was studied in residential systems. Factors such as deficient chlorine levels, pipe repairs and other work, water flow interruptions, the use of alternative water sources, inadequate cleaning operations in public water reservoirs, and the position of the home within the public network (and whether this location constituted an endpoint) were studied in public water supply systems. Levels of legionellae in domestic water samples were also measured. Although the use of water reservoirs and hot water tanks promotes colonization by legionellae in residential systems, none of the variables studied seems to increase the incidence of community-acquired Legionnaires' disease.


Assuntos
Legionella pneumophila/isolamento & purificação , Doença dos Legionários/epidemiologia , Doença dos Legionários/etiologia , Microbiologia da Água , Abastecimento de Água , Estudos de Casos e Controles , Coleta de Dados , Feminino , Humanos , Incidência , Doença dos Legionários/diagnóstico , Masculino , Probabilidade , Valores de Referência , Medição de Risco , Sensibilidade e Especificidade , Espanha/epidemiologia
11.
EMBO J ; 17(10): 2926-37, 1998 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-9582286

RESUMO

Of the proteins required for pre-mRNA splicing, at least four, the DEAH-box proteins, are closely related due to the presence of a central 'RNA helicase-like' region, and extended homology through a large portion of the protein. A major unresolved question is the function of these proteins. Indirect evidence suggests that several of these proteins are catalysts for important structural rearrangements in the spliceosome. However, the mechanism for the proposed alterations is presently unknown. We present evidence that PRP22, a DEAH-box protein required for mRNA release from the spliceosome, unwinds RNA duplexes in a concentration- and ATP-dependent manner. This demonstrates that PRP22 can modify RNA structure directly. We also show that the PRP22-dependent release of mRNA from the spliceosome is an ATP-dependent process and that recombinant PRP22 is an ATPase. Non-hydrolyzable ATP analogs did not substitute for ATP in the RNA-unwinding reaction, suggesting that ATP hydrolysis is required for this reaction. Specific mutation of a putative ATP phosphate-binding motif in the recombinant protein eliminated the ATPase and RNA-unwinding capacity. Significantly, these data suggest that the DEAH-box proteins act directly on RNA substrates within the spliceosome.


Assuntos
Adenosina Trifosfatases/metabolismo , Trifosfato de Adenosina/metabolismo , Proteínas Fúngicas/metabolismo , RNA Helicases , Splicing de RNA , RNA de Cadeia Dupla , Proteínas de Saccharomyces cerevisiae , Spliceossomos , Adenosina Trifosfatases/genética , RNA Helicases DEAD-box , Proteínas Fúngicas/genética , Teste de Complementação Genética , Hidrólise , Mutação , Fenótipo , Fatores de Processamento de RNA , RNA Mensageiro/metabolismo , RNA Nuclear Pequeno , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Ribonucleoproteína Nuclear Pequena U4-U6/genética
12.
RNA ; 1(2): 132-45, 1995 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-7585243

RESUMO

Prp24 was previously isolated as a suppressor of a cold-sensitive U4 mutation and is required for at least the first step of splicing in vitro. Our investigation of the in vitro RNA binding properties of the purified Prp24 protein shows that it binds preferentially to the U4/U6 hybrid snRNAs compared to other snRNAs. The interaction between Prp24 and the U4/U6 hybrid appears to involve two regions in the RNA: the 39-57 region of U6 and stem II of the U4/U6 hybrid. Interestingly, some U4 mutations, which destabilize stem II, increase the affinity of Prp24 for the U4/U6 RNAs compared to the wild type. This suggests that the binding of Prp24 to the U4/U6 RNAs may involve some destabilization of the RNA duplex. We also found that Prp24 can stimulate the annealing of U4 and U6, suggesting that Prp24 participates in both the formation and disassembly of the U4/U6 hybrid during splicing.


Assuntos
Proteínas de Ligação a RNA/metabolismo , Proteínas Repressoras/metabolismo , Ribonucleoproteína Nuclear Pequena U4-U6/metabolismo , Sequência de Bases , Radical Hidroxila , Ligantes , Dados de Sequência Molecular , Mutação , Sondas de Oligonucleotídeos , RNA/metabolismo , Splicing de RNA , RNA Nuclear Pequeno/metabolismo , Spliceossomos/metabolismo , Relação Estrutura-Atividade , Temperatura
13.
Int J Biol Macromol ; 13(6): 345-8, 1991 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-1772825

RESUMO

The kinetics of the reaction of the thiol residue in Zn(2+)-dependent beta-lactamase II with 5,5'-dithiobis[2-nitrobenzoic acid], and the concomitant inactivation revealed that both events take place at the same rate. The inactivation could not be reverted by incubation with Zn2+ or by using a substrate concentration about eight times the Km of the enzyme. EDTA incubation also produced inactivation of the enzyme, although it was reverted by increasing the substrate concentration in the assay. A dual role is proposed for Zn2+ in beta-lactamase. The kinetic analysis of the thiol modification and the concomitant inactivation is in agreement with previous reports on the implication of the metal ion in catalysis. A role in stabilizing the native structure of the enzyme is also suggested.


Assuntos
Cefalosporinase/química , Ácido Ditionitrobenzoico/química , Zinco/química , Bacillus/enzimologia , Cefalosporinase/metabolismo , Ácido Ditionitrobenzoico/metabolismo , Ativação Enzimática , Cinética , Zinco/metabolismo
14.
Int J Biol Macromol ; 13(4): 225-30, 1991 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-1777429

RESUMO

The system composed of 2-amino-2-hydroxymethylpropane-1,3-diol (Tris) and Zn2+ catalyses the degradation of cephalosporins. The beta-lactam opening fits to a first-order process, with a constant directly proportional to the zinc ion concentration. The pH and Tris concentration dependency displayed by the first-order constant, as well as the nature of the degradation products point to a mechanism that can be considered as an extension of that proposed for the benzylpenicillin degradation. The mechanism proposed here, and the values of the kinetic constants calculated, as compared with those of beta-lactamases, lead to the conclusion that the Tris-Zn2+ system simulates the catalytic action of the serine beta-lactamases rather than the action of the Zn(2+)-dependent type of enzymes.


Assuntos
Antibacterianos/química , Trometamina , Zinco , beta-Lactamases/metabolismo , Antibacterianos/metabolismo , Cefaloridina/química , Cinética , Matemática , Modelos Químicos , Modelos Teóricos , Relação Estrutura-Atividade
15.
Antimicrob Agents Chemother ; 35(7): 1517-9, 1991 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-1929321

RESUMO

The low Zn2+ complex formation constants, the capacity to degrade penicillin G in combination with Zn2+, and UV absorbance make 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid, 3-[N-tris(hydroxymethyl)methylamino]-2-hydroxypropanesulfonic acid, 1,3-bis[tris(hydroxymethyl)methylamino]propane, and 1,4-piperazinediethanesulfonic acid convenient buffers to study Zn(2+)-dependent beta-lactamases.


Assuntos
Zinco/metabolismo , beta-Lactamases/análise , Bacillus cereus/enzimologia , Soluções Tampão , Cinética , Penicilina G/farmacologia , Espectrofotometria Ultravioleta
16.
Nature ; 349(6309): 487-93, 1991 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-1992352

RESUMO

The product of the yeast PRP22 gene acts late in the splicing of yeast pre-messenger RNA, mediating the release of the spliced mRNA from the spliceosome. The predicted PRP22 protein sequence shares extensive homology with that of PRP2 and PRP16 proteins, which are also involved in nuclear pre-mRNA splicing. The homologous region contains sequence elements characteristic of several demonstrated or putative ATP-dependent RNA helicases. A putative RNA-binding motif originally identified in bacterial ribosomal protein S1 and Escherichia coli polynucleotide phosphorylase has also been found in PRP22.


Assuntos
Proteínas de Transporte/fisiologia , Proteínas Fúngicas/metabolismo , Splicing de RNA , RNA Mensageiro/metabolismo , Proteínas de Saccharomyces cerevisiae , Trifosfato de Adenosina/metabolismo , Sequência de Aminoácidos , Sequência de Bases , Clonagem Molecular , RNA Helicases DEAD-box , Teste de Complementação Genética , Temperatura Alta , Substâncias Macromoleculares , Dados de Sequência Molecular , Família Multigênica , RNA Helicases , RNA Nucleotidiltransferases/genética , Fatores de Processamento de RNA , Mapeamento por Restrição , Saccharomyces cerevisiae
17.
Plasmid ; 23(2): 159-62, 1990 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-2194231

RESUMO

A yeast-Escherichia coli shuttle vector containing the M13 origin of replication has been constructed. This vector allows selection and replication in both Saccharomyces cerevisiae and E. coli, as well as single-stranded packaging from E. coli upon infection with a helper phage. The presence of a polylinker with various unique restriction sites facilitates the cloning of desired genes.


Assuntos
Colífagos/genética , Replicação do DNA , Escherichia coli/genética , Vetores Genéticos , Plasmídeos , Saccharomyces cerevisiae/genética , Sequência de Bases , Clonagem Molecular , Escherichia coli/crescimento & desenvolvimento , Mitose , Dados de Sequência Molecular , Mapeamento por Restrição , Saccharomyces cerevisiae/citologia
18.
Genes Dev ; 3(8): 1206-16, 1989 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-2676722

RESUMO

In this study we report the isolation of temperature-sensitive mutants that affect pre-mRNA splicing. A bank of approximately 1000 temperature-sensitive Saccharomyces cerevisiae strains was generated and screened on RNA gel blots by hybridization with an actin intron probe. We isolated 16 mutants defining 11 new complementation groups prp(rna)17-prp(rna)27 with four phenotypic classes of mutants and 21 mutants in the prp2-prp11 complementation groups (formerly rna2-rna11). The majority of the complementation groups share a phenotype of pre-mRNA accumulation, seen in all of the prp(rna)2-prp(rna)11 mutants. Three novel classes of mutants were isolated in this study. One class, consisting of two complementation groups, exhibits an accumulation of the lariat intermediate of splicing, with no change in the levels of pre-mRNA. The second class, also represented by two complementation groups, shows an accumulation of the intron released after splicing. The third novel class, comprising one complementation group, accumulates both pre-mRNA and the released intron. All mutants isolated were recessive for the splicing phenotype. Only 2 of the 11 complementation groups, although recessive, were not temperature sensitive. This study, together with previous isolation of the prp(rna)2-prp(rna)11 groups and the spliceosomal snRNAs, puts at least 26 gene products involved directly or indirectly in pre-mRNA splicing.


Assuntos
Precursores de RNA/genética , Splicing de RNA , Saccharomyces cerevisiae/genética , Alelos , Genes Fúngicos , Genes Letais , Teste de Complementação Genética , Íntrons , Mutação , Fenótipo , RNA Fúngico/genética , Temperatura
19.
Mol Cell Biol ; 8(12): 5299-309, 1988 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-2854195

RESUMO

Ty transposable-element insertion mutations of Saccharomyces cerevisiae can cause cell-type-dependent activation of adjacent-gene expression. Several cis-acting regulatory regions within Ty1 are responsible for the effect of Ty1 on adjacent-gene expression. One of these is the block II sequence that was defined by its homology to mammalian enhancers and to the yeast a1-alpha 2 control site. Tandem copies of a 57-base-pair region encompassing block II caused an additive increase in expression of the CYC7 reporter gene in the absence of other Ty1 sequences. The activation of gene expression by the multiple repeats was abolished in a/alpha diploid cells. A specific complex between a constitutive factor in whole-cell extracts and the DNA regulatory element was observed. The protein-binding site for the constitutive factor coincided with the block II element. Base-pair substitutions within the binding site abolished the ability of the block II element to function as a component of the Ty1 activator and to form the factor-DNA complex. The correlation between complex formation and reporter gene expression indicates that factor binding to the cis-acting element is essential for this element to function as a component of the Ty1 activator.


Assuntos
Elementos de DNA Transponíveis , Regulação da Expressão Gênica , Genes Fúngicos , Genes Reguladores , Sequências Reguladoras de Ácido Nucleico , Saccharomyces cerevisiae/genética , Sequência de Bases , Clonagem Molecular , Proteínas de Ligação a DNA/metabolismo , Genótipo , Dados de Sequência Molecular , Mutação , Mapeamento por Restrição
20.
Anal Biochem ; 173(2): 235-40, 1988 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-3189806

RESUMO

Glycogen phosphorylase (EC 2.4.1.1) may be assayed in the glycogen degradation direction by a continuous spectrophotometric method. The formation of glucose 1-phosphate from glycogen and phosphate produces a controlled change of pH which can be measured by the changes in absorbance of phenol red added to the system. The procedure may be conveniently applied to a stopped-flow spectrophotometer to measure the rate of the reaction. Therefore the activity of the enzyme may be determined at low conventional concentrations and, by the same technique, at high enzyme concentrations approaching those supposed to exist in vivo.


Assuntos
Fosforilases/análise , Animais , Catálise , Coelhos , Espectrofotometria
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