Avaliação da infecção por Parvovírus Humano B19 em diferentes grupos populacionais: diagnóstico diferencial e aspectos imunopatogênicos da infecção aguda e persistente / Evaluation of Human Parvovirus B19 infection in different population groups: differential diagnosis and immunopathogenic aspects of acute and persistent infection

A infecção pelo Parvovírus B19 (B19V) pode ocorrer em indivíduos imunocompetentes e imunocomprometidos, de todas as faixas etárias, e se caracteriza por ser aguda e autolimitada, podendo levar a quadros de doença exantemática (DE), doença febril aguda (DFA), doença renal crônica (DRC) e falência hepática aguda (FHA). O diagnóstico diferencial de B19V nessas populações, muitas vezes, não ocorre e estudos sobre a prevalência do B19V são antigos e escassos, não refletindo a atualidade. Marcadores da infecção podem ser detectados na circulação e em diferentes tipos de tecidos, inclusive em tecidos não eritroides, por meses ou anos. A infecção pode levar a manifestações clínicas graves, que requer tratamento hospitalar, e a doenças inflamatórias atípicas, como: cardiomiopatia, artrite reumatoide, hepatite e vasculite. No entanto, a detecção de B19V DNA não implica necessariamente na presença de vírions infecciosos e na associação do B19V com essas manifestações atípicas. Dessa forma, o objetivo do trabalho foi otimizar técnicas de PCR em tempo real para quantificação do B19V DNA e de detecção de partículas virais infecciosas, a fim de realizar o diagnóstico diferencial da infecção pelo B19V em pacientes com DE, DFA, DRC e FHA. Para o diagnóstico da infecção, amostras de diferentes populações foram testadas: DE (n=54), DFA (n=60), DRC (n=221), e FHA (n=30). Amostras de soro (e de tecido hepático para FHA) foram submetidas a avaliação de marcadores sorológicos (IgM e IgG anti-B19V) e moleculares do B19V, a fim de determinar a fase da infecção em que o paciente se encontrava. Para a avaliação de marcadores moleculares, a metodologia de PCR quantitativo e em tempo real foi otimizada e permitiu um diagnóstico sensível e específico do B19V DNA. Além disso, a presença de vírions em amostras de pacientes com B19V (n=10) e de macacos cynomolgus (n=4) infectados experimentalmente foram avaliadas por meio da técnica de pré-tratamento das amostras com uma enzima endonuclease. O teste molecular (qPCR) otimizado durante o estudo, apresentou sensibilidade e especificidade de 100%. O ensaio com a endonuclease revelou que a maioria das amostras de soro humano tornou-se B19V DNA negativa após o pré-tratamento, indicando que não eram infecciosas. Foi observado prevalências do B19V DNA em 5,5% dos pacientes com DE; 6,6% em DFA; 65,6% em DRC, e 23,3% em FHA. Como conclusão a técnica de qPCR otimizada no presente estudo foi efetiva para o esclarecimento de casos da infecção por B19V e é adequada para diagnóstico diferencial. Além disso, o teste laboratorial baseado em endonuclease possibilitou a discriminação do B19V DNA (se encapsidado em vírions ou não). Portanto, estes testes podem ser utilizados para esclarecer o papel do B19V como agente etiológico associado a diversas manifestações clínicas. As prevalências encontradas nesse estudo indicam que o B19V está circulando entre os diversos grupos populacionais estudados e deve ser feita uma melhor vigilância da infecção, pois está presente tanto em indivíduos imunocompetentes como em imunocomprometidos. Além disso, os resultados sugerem a importância da inclusão de B19V no diagnóstico laboratorial diferencial, não apenas para fins epidemiológicos, mas também para o manejo adequado do paciente.

Parvovirus B19 (B19V) infection can occur in immunocompetent and immunocompromised individuals of all group ages and is characterized as acute and self limiting, which can lead to rash disease (RD), acute febrile illness (AFI), chronic kidney disease (CKD), and acute liver failure (ALF). Differential diagnosis of B19V in these populations often does not occur and studies on the prevalence of B19V are scarce, outdated, and do not reflect the current situation. B19V markers of acute infection can be detected in the circulation and in different tissue types, including non-erythroid tissues, for months to years and may lead to severe clinical manifestations, requiring hospital treatment, and to atypical inflammatory diseases, such as cardiomyopathy, rheumatoid arthritis, hepatitis, and vasculitis. However, the detection of B19V DNA does not necessarily imply the presence of infectious virions and the causal relation between B19V and atypical manifestations could not be proved yet. Thus, the aim of this study was to standardize the real-time PCR for quantification of B19V DNA and detection of infectious viral particles in order to perform the differential diagnosis of the B19V infection in RD, AFI, CKD, and ALF patients. For the diagnosis of the infection, samples from different populations were tested: RD (n=54), AFI (n=60), CKD (n=221), and ALF (n=30). Serum samples (and hepatic tissue for ALF) were submitted to the evaluation of B19V serological status (anti-B19V IgM and IgG antibodies) and molecular markers, in order to determine the stage of infection in which the patient is. For the evaluation of molecular markers, a quantitative real-time PCR methodology was optimized and allowed a sensitive and specific diagnosis of B19V DNA. In addition, the presence of virions in samples from patients with B19V (n=10) and from cynomolgus monkeys (n=4) experimentally infected were evaluated by endonuclease enzyme pretreatment. The molecular test optimized during the study showed 100% sensitivity and specificity. The endonuclease treatment assay revealed that most human serum samples became negative after pretreatment, as indicative of non-infective particles. Concerning the prevalence of B19V DNA: 5.5% were obtained in patients with RD; 6.6% in AFI; 65.6% in CKD, and 23.3% in ALF. In conclusion, the qPCR technique optimized in the present study was effective for clarifying cases of B19V infection and is suitable for differential diagnosis. In addition, the endonuclease-based laboratory test made it possible to discriminate B19V DNA (whether encapsidated in virions or not). Therefore, these tests can be used to clarify the role of B19V as an etiologic agent associated with several clinical manifestations. The prevalence found in this study indicate that B19V is circulating among the different populational groups that have been studied and better surveillance of the infection should be carried out, as it is present in both immunocompetent and immunocompromised individuals. In addition, the results suggest the importance of including B19V in the differential laboratory diagnosis, not only for epidemiological purposes but also for the proper management of the patient.

Evaluation of nuclear NF-κB, transglutaminase2, and ERCC1 as predictors of platinum resistance in testicular tumors

ABSTRACT Purpose: Testicular germ cells tumor (TGCT) are associated with a high cure rate and are treated with platinum-based chemotherapy. However, a group of testicular cancer patients may have a very unfavorable evolution and insensitivity to the main therapeutic agent chemotherapy (CT) cisplatin. The aim of this study was to evaluate the risk of recurrence and overall survival related to the expression of nuclear factor kappa-B (NF-κB), transglutaminase 2 (TG2) and excision repair cross-complementation group 1 (ERCC1) in patients with TGCT treated with platinum combinations. Patients and Methods: A retrospective study was performed with TGCT patients treated with platinum-based chemotherapy. Immunohistochemical analysis was performed and the expression was correlated with clinical and laboratory data. Results: Fifty patients were included, the mean age was 28.4 years (18 to 45), and 76% were non-seminoma. All patients were treated with standard cisplatin, etoposide and bleomycin or cisplatin, and etoposide. Patient's analyzed immunodetection for NF-κB, TG2, and ERCC1 were positive in 76%, 54% and 42%, respectively. Multivariate analysis identified that positive expressions to ERCC1 and NF-κB are independent risk factors for higher recurrence TGCT after chemotherapy (RR 2.96 and 3.16, respectively). Patients with positive expression of ERCC1 presented a poor overall survival rate for 10-year follow (p=0.001). Conclusions: The expression of ERCC1 and NF-κB give a worse prognosis for relapse, and only ERCC1 had an influence on the overall survival of TGCT patients treated with platinum-based chemotherapy. These may represent markers that predict poor clinical outcome and response to cisplatin.

Radiotherapy modulates expression of EGFR, ERCC1 and p53 in cervical cancer

Cervical cancer is a public health problem and the molecular mechanisms underlying radioresistance are still poorly understood. Here, we evaluated the modulation of key molecules involved in cell proliferation, cell cycle and DNA repair in cervical cancer cell lines (CASKI and C33A) and in malignant tissues biopsied from 10 patients before and after radiotherapy. The expression patterns of epidermal growth factor receptor (EGFR), excision repair cross-complementation group 1 (ERCC1) and p53 were evaluated in cancer cell lines by quantitative PCR and western blotting, and in human malignant tissues by immunohistochemistry. The mutation status of TP53 gene was evaluated by direct sequencing. Among cell lines, absent or weak modulations of EGFR, ERCC1 and p53 were observed after exposure to 1.8 Gy. Conversely, increased expressions of p53 (5/10 patients; P=0.0239), ERCC1 (5/10 patients; P=0.0294) and EGFR (4/10 patients; P=0.1773) were observed in malignant tissues after radiotherapy with the same radiation dose. TP53 mutations were found only in one patient. Here we show that a single dose of radiotherapy induced EGFR, ERCC1 and p53 expression in malignant tissues from cervical cancer patients but not in cancer cell lines, highlighting the gap between in vitro and in vivo experimental models. Studies on larger patient cohorts are needed to allow an interpretation that an upregulation of p53, EGFR and ERCC1 may be part of a radioresistance mechanism.

Relationship between the Asp1104His polymorphism of the nucleotide excision repair gene ERCC5 and treatment sensitivity to oxaliplatin in patients with advanced colorectal cancer in China

OBJECTIVES: To study the relationship between the Asp1104His polymorphism of the nucleotide excision repair gene ERCC5 and treatment sensitivity to oxaliplatin in patients with advanced colorectal cancer (CRC) in China. METHODS: A group of 226 patients in the Department of Gastrointestinal Oncology at Zhejiang Xiaoshan Hospital from July 2011∼December 2016 and a control group of 226 normal healthy individuals were involved in this study. All patients were first diagnosed with advanced CRC and were treated with oxaliplatin-based chemotherapy. The genotype of ERCC5 at the site of amino acid 1104 was determined by a TaqMan probe-based real-time PCR approach. RESULTS: There were no differences in age or gender between the groups, but the percentages of smokers and individuals with a family history of cancer were significantly higher in the patient group than in the control group. Analysis of the G/C polymorphism frequency among the patients and the healthy controls showed that the frequencies of the CC genotype and the CC+GC genotype were significantly related to CRC, but no significant difference in these frequencies was found between genders. The analysis of the relationship between the 5-year survival rate and different genotypes showed that in the total patient group, regardless of gender, the 5-year survival rate was significantly associated with the Asp1104His polymorphism of ERCC5. CONCLUSIONS: The Asp1104His polymorphism of ERCC5 was associated with the risk and 5-year survival rate of CRC as well as treatment sensitivity to oxaliplatin.

Enzyme activity and thermostability of a non-specific nuclease from Yersinia enterocolitica subsp. palearctica by site-directed mutagenesis

Background: To identify the critical amino acid residues that contribute to the high enzyme activity and good thermostability of Yersinia enterocolitica subsp. palearctica (Y. NSN), 15 mutants of Y. NSN were obtained by site-directed mutagenesis in this study. And their enzyme activity and thermostability were assayed. Effect of several factors on the enzyme activity and thermostability of Y. NSN, was also investigated. Results: The results showed that the I203F and D264E mutants retained approximately 75% and 70% enzyme activity, respectively, compared to the wild-type enzyme. In addition to the I203F and D264E mutants, the mutant E202A had an obvious influence on the thermostability of Y. NSN. According to the analysis of enzyme activity and thermostability of Y. NSN, we found that Glu202, Ile203 and Asp264 might be the key residues for its high enzyme activity and good thermostability. Conclusions: Among all factors affecting enzyme activity and thermostability of Y. NSN, they failed to explain the experimental results well. One reason might be that the enzyme activity and thermostability of Y. NSN were affected not only by a single factor but also by the entire environment.

Benefits of maltodextrin intake 2 hours before cholecystectomy by laparotomy in respiratory function and functional capacity: a prospective randomized clinical trial / Benefícios na função respiratória e capacidade funcional com ingesta de maltodextrina 2 horas antes de colecistectomia por laparotomia: ensaio clínico prospectivo e randomizado

ABSTRACT Objective: To evaluate the change in respiratory function and functional capacity according to the type of preoperative fasting. Methods: Randomized prospective clinical trial, with 92 female patients undergoing cholecystectomy by laparotomy with conventional or 2 hours shortened fasting. The variables measured were the peak expiratory flow, forced expiratory volume in the first second, forced vital capacity, dominant handgrip strength, and non-dominant handgrip strength. Evaluations were performed 2 hours before induction of anesthesia and 24 hours after the operation. Results: The two groups were similar in preoperative evaluations regarding demographic and clinical characteristics, as well as for all variables. However, postoperatively the group with shortened fasting had higher values than the group with conventional fasting for lung function tests peak expiratory flow (128.7±62.5 versus 115.7±59.9; p=0.040), forced expiratory volume in the first second (1.5±0.6 versus 1.2±0.5; p=0.040), forced vital capacity (2.3±1.1 versus 1.8±0.9; p=0.021), and for muscle function tests dominant handgrip strength (24.9±6.8 versus 18.4±7.7; p=0.001) and non-dominant handgrip strength (22.9±6.3 versus 17.0±7.8; p=0.0002). In the intragroup evaluation, there was a decrease in preoperative compared with postoperative values, except for dominant handgrip strength (25.2±6.7 versus 24.9±6.8; p=0.692), in the shortened fasting group. Conclusion: Abbreviation of preoperative fasting time with ingestion of maltodextrin solution is beneficial to pulmonary function and preserves dominant handgrip strength. .

RESUMO Objetivo: Avaliar a alteração da função respiratória e da capacidade funcional, conforme o tipo de jejum pré-operatório. Métodos: Ensaio clínico prospectivo randomizado, com 92 pacientes do sexo feminino, submetidas à colecistectomia por laparotomia, observando jejum convencional ou abreviado de 2 horas com maltodextrina. As variáveis foram: pico de fluxo expiratório, volume expiratório no primeiro segundo, capacidade vital forçada, força de preensão palmar dominante e força de preensão palmar não dominante. As avaliações foram realizadas 2 horas antes da indução anestésica e 24 horas após a operação. Resultados: Os dois grupos foram semelhantes quanto às características demográficas, clínicas e em todas as variáveis estudadas, quando avaliadas no pré-operatório. No entanto, no pós-operatório, o grupo abreviado apresentou valores maiores que o grupo convencional para pico de fluxo expiratório (128,7±62,5 versus 115,7±59,9; p=0,040), volume expiratório no primeiro segundo (1,5±0,6 versus 1,2±0,5; p=0,040), capacidade vital forçada (2,3±1,1 versus 1,8±0,9; p=0,021), força de preensão palmar dominante (24,9±6,8 versus 18,4±7,7; p=0,001) e força de preensão palmar não dominante (22,9±6,3 versus 17,0±7,8; p=0,0002). Na avaliação intragrupo, houve diminuição nas variáveis ao se compararem os valores do pré-operatório em relação ao pós-operatório, exceto para força de preensão palmar dominante (25,2±6,7 versus 24,9±6,8; p=0,692) no grupo de jejum abreviado. Conclusão: A abreviação do tempo de jejum pré-operatório com solução contendo maltodextrina beneficia a função pulmonar e preserva a força de preensão palmar dominante. .

Té verde, fitomedicamento contra la influenza A: rol de las catequinas / Green tea, phytomedicine against influenza A: role of catechins

The highly variable Influenza A is constantly changed in new forms, like avian influenza or actual pandemic swine flu, has forced to massive use of antiviral drugs. Neuraminidase inhibitors are those with acceptable risk – efficacy profile. However, high variability of neuraminidase among different Influenza A viruses has resulted in viral resistance. Searching for new therapeutic resources, green tea (Camelia sinensis) has been reported to inhibit Influenza A virus replication, due to its catechines that bind to the active pocket endonuclease domain of viral RNA-dependent RNA polymerase. This enzyme is highly conserved among influenza A virus variants. So, a Camelia sinensis catechine standardized extract could become an anti endonuclease herbal drug.

La constante aparición de nuevas variantes de la Influenza A, como la denominada influenza aviar y la más reciente gripe porcina, de características pandémicas, ha obligado al uso masivo de fármacos antivirales. Los únicos con un perfil riesgo – eficacia aceptable son los inhibidores de la neuraminidasa. Sin embargo, la poca conservación entre la neuraminidasa de las diferentes cepas de virus Influenza A, han evidenciado resistencia viral. En la búsqueda de nuevos recursos terapéuticos, se ha reportado que el té verde (Camelia sinensis), gracias a su contenido de catequinas, puede inhibir la replicación de virus Influenza A, al unirse específicamente al bolsillo activo del dominio endonucleasa de la polimerasa de ARN dependiente de ARN viral, una enzima que posee un alto grado de conservación entre las diferentes variantes del virus de la Influenza A. Un extracto de Camelia sinensis estandarizado en catequinas podría constituirse en un fitofármaco antiendonucleasa.

Preliminary studies investigating the occurrence of Biomphalaria cousini in Brazil

Specific genetic profiles of Brazilian Biomphalaria species were previously standardized by molecular taxonomy through the analysis of restriction fragments, which were generated by digesting the internal transcribed spacer region of rDNA with the DdeI endonuclease. Biomphalaria amazonica displayed three distinct profiles. To investigate these distinct profiles, the same molecular technique, polymerase chain reaction and restriction fragment length polymorphism, was used with different endonucleases. In addition, morphological data were also used to compare B. amazonica specimens that were collected from Brazil, Colombia and Bolivia. The morphological characters of Bolivian molluscs were similar to B. amazonica, displayed a molecular profile of five restriction fragments and morphological data, whereas the Colombian mollusc population showed morphological characters similar to Biomphalaria cousini and a molecular profile of three restriction fragments, similar to B. cousini. The Brazilian specimens showed the B. amazonica and B. cousini molecular profiles as well as a third profile, which resembled a combination of the Colombian and Bolivian molecular profiles.

Multidrug efflux systems in Escherichia coli and Enterobacter cloacae obtained from wholesome broiler carcasses / Sistemas de efluxo multidroga em Escherichia coli e Enterobacter cloacae obtidas de carcaças de frangos sadios

Members of the Enterobacteriaceae family are present in the intestines of man and animals as commensals or are important disease causing agents. Bacteria bearing multidrug efflux systems (MDR) are able to survive adverse ecological niches. Multiresistant Escherichia coli and Enterobacter cloacae isolates from wholesome broiler carcasses were investigated for the presence of MDR. Lowering of Minimal Inhibitory Concentration for antimicrobials in the presence of a proton-motive force (PMF) uncoupler was tested as a potential display of the MDR phenotype. PCR amplification of the genes encoding AcrA and AcrB, components of a MDR system was performed. Diversity of each species was ascertained by Pulsed-Field Gel Electrophoresis (PFGE) of DNA digested with endonuclease XbaI. For all the isolates, except E. coli 1 and E. cloacae 9, lowering of MIC or of the growth rate in the presence of antimicrobials was observed, indicating a PMF dependent resistance mechanism. Expected products of DNA amplification with acrAB derived primers was obtained with all E. coli strains and with two of the five E. cloacae strains. Dendrogram generated shows diverse pulsetypes, confirming the genetic diversity among the strains. An important issue and related public health is the fact that different models and mechanisms of antimicrobial resistance are present in a small number of non-pathogenic strains and isolated from the same origin. These may be sources of resistance genes to others microorganisms, among them, pathogenic strains.

Os membros da família Enterobacteriaceae estão presentes no intestino do homem e dos animais como comensais ou agentes causadores de doença importantes. Bactérias multirresistentes podem possuir sistemas de efluxo multidrogas (MDR) sendo capazes de sobreviver em nichos ecológicos adversos. Escherichia coli e Enterobacter cloacae, multirresistentes, isoladas de frangos sadios foram investigadas quanto à presença de MDR. A diminuição da concentração inibitória mínima de antimicrobianos, na presença de um desacoplador da força próton motora (PMF), foi usada para detectar o fenótipo MDR. Foi realizada PCR dos genes codificadores de AcrA e AcrB, componentes de um sistema MDR. A diversidade de cada isolado foi confirmada por eletroforese em gel de campo pulsado (PFGE) usando a endonuclease XbaI. Observou-se em todos os isolados, exceto E. coli 1 e E. cloacae 9, uma diminuição das MICs ou das curvas de crescimento na presença dos antimicrobianos, indicando um mecanismo de resistência dependente da PMF. Os produtos amplificados esperados derivados de acrAB foram obtidos em todos os isolados de E. coli e em dois, dos cinco, de E. cloacae. O dendrograma gerado mostra diferentes perfis de bandas (pulsetypes), confirmando a diversidade genética entre os isolados. Uma questão importante e relacionada à saúde publica é o fato de que diferentes modelos e mecanismos de resistência aos antimicrobianos estão presentes em um número reduzidos de isolados não patogênicos e obtidos de uma mesma origem. Esses podem ser fontes de genes de resistência para outros microorganismos, entre eles, cepas patogênicas.

Longitudinal study on occurrence of adenoviruses and hepatitis A virus in raw domestic sewage in the city of Limeira, São Paulo / Estudo longitudinal da ocorrência de adenovírus e vírus da hepatite A em esgoto doméstico na cidade de Limeira, SP

The aim of this study was to verify the presence and annual distribution of adenoviruses and hepatitis A virus in domestic sewage in the city of Limeira, São Paulo. Fifty samples with a volume of 8 liters each were collected weekly from December 2004 to December 2005. The viruses were concentrated by filtration through positively charged ZP60S filter membranes, followed by ultracentrifugation. Human adenoviruses (HAdV) were detected by PCR followed by nested-PCR and screening for species F was done by restriction of the PCR product with TaqI endonuclease. Virus infectivity assays were performed by inoculation of concentrates onto HEp-2 cell monolayers. RT-PCR was used for the detection of hepatitis A virus. HAdV were detected in all samples, and 64% of samples were positive for infectious virus. Species F was present in 82% of the samples. Hepatitis A virus was detected in 48% of the samples. These results demonstrate that HAdV and HAV were present in the domestic sewage of Limeira throughout the period of study, demonstrating the importance of an adequate treatment before the disposal in the environment.

O objetivo do estudo foi verificar a ocorrência e a distribuição anual de adenovírus humanos e vírus da Hepatite A (VHA) no efluente doméstico da cidade de Limeira, São Paulo, ao longo do período de Dezembro de 2004 e Dezembro de 2005, com vistas à futura implementação de sistemas de tratmento de água de esgoto. Cinquenta amostras de efluente bruto com volume de 8L cada foram colhidas semanalmente e os vírus concentrados por filtração em membrana eletropositiva ZP60S, seguida de ultracentrifugação. Adenovírus foram detectados por PCR e nested-PCR. Adenovírus da espécie F foram distinguidos das demais por restrição do produto da PCR com endonuclease TaqI. Ensaios de infectividade viral foram realizados em culturas de células HEp-2. A presença do vírus da hepatite A também foi pesquisada nas mesmas amostras, fazendo-se uso de método de RT-PCR. Adenovírus foram detectados em todas as amostras, sendo a espécie F identificada em 82% destas. Sessenta e quatro por cento dos adenovírus detectados ainda estavam infecciosos. O vírus da Hepatite A foi detectado em 48% das amostras examinadas. Estes resultados evidenciam a presença e a circulação de Adenovírus humano e VHA nas águas de esgoto doméstico de Limeira ao longo do período de estudo, demonstrando a importância de um tratamento adequado desse material antes da disposição no meio ambiente.

Isolation and characterization of BliAI, an isoschizomer of ClaI from Bacillus licheniformis

The restriction endonuclease BliAI, an isoschizomer of ClaI, which recognizes the sequence 5'- AT¼CGAT - 3', was purified from a natural isolate identified as Bacillus licheniformis. The restriction endonuclease was isolated from cell extracts using single-step purification by phosphocellulose column chromatography. The restriction endonuclease is active at 37°C and over a wide range of pH and salt concentration. The molecular weight of the purified restriction enzyme is consistent with a value of 39 kDa.

A endonuclease de restrição BliAI, um isoesquisômero de ClaI, que reconhece a seqüência 5'- AT¼CGAT - 3', foi purificada de um isolado natural identificado como Bacillus licheniformis. A endonuclease de restrição em questão foi isolada a partir de um extrato celular em um único passo cromatográfico utilizando uma coluna contendo a resina fosfocelulose. A endonuclease de restrição é ativa à 37°C e em uma ampla escala de pH e concentração de sais. O peso molecular da enzima purificada corresponde a um valor de kDa 39.

Determinación del sexo y genotipificación del gen de la k-caseína en embriones bovinos / Sex determination and genotyping the casein gene of bovine embryo

La leche de las vacas que portan el alelo B del gen de la k-caseína presenta un rendimiento cualitativo y cuantitativo superior en la producción de quesos, comparado con el obtenido con la leche de las vacas que tienen el alelo A, este último se encuentra con mayor frecuencia en la raza Holstein, la cual representa el 70 por ciento de los hatos lecheros en Colombia. Lo anterior plantea el reto de cambiar las proporciones genotípicas de esta característica al seleccionar individuos utilizando marcadores moleculares, para lo cual se estandarizó una técnica que permite la genotipificación del gen de la k-caseína y la determinación del sexo en embriones bovinos. Se realizó una PCR ¡¡ãsemi-anidada¡¡À, en la que se utilizó un juego de cebadores (K01F y JK3.1) para amplificar una región de 563pb del gen de la k-caseína, el cual fué sometido a una segunda amplificación utilizando el juego de cebadores (JK5.1 y JK3.1), obteniéndose un fragmento de 344pb el cual presenta un polimorfismo que puede ser identificado mediante la digestión con una endonucleasa de restricción (RFLP); donde el patrón de fragmentos de 215 y 129 pb corresponde al alelo B y 344 pb al alelo A, cuando se utilizó Hind III. El patrón de fragmentos de 263 y 81 pb en el alelo B y 132, 131 y 84 pb en el alelo A, cuando se utilizó Hinf I. Finalmente, se utilizó un juego de cebadores (SRY1F y SRY2R) específicos para una región del gen sry de bovino, donde los individuos que presentaron un fragmento de 151pb se clasificaron como machos. Estos resultados muestran la posibilidad de genotipificación simultánea de las variantes de la k-caseína y la determinación del sexo en embriones de bovino, lo cual permite el desarrollo de un programa de selección de embriones con las características genéticas que la ganadería y la industria de los derivados lácteos requiere en nuestro medio.

A simple RT-PCR-based strategy for screening connexin identity

Vertebrate gap junctions are aggregates of transmembrane channels which are composed of connexin (Cx) proteins encoded by at least fourteen distinct genes in mammals. Since the same Cx type can be expressed in different tissues and more than one Cx type can be expressed by the same cell, the thorough identification of which connexin is in which cell type and how connexin expression changes after experimental manipulation has become quite laborious. Here we describe an efficient, rapid and simple method by which connexin type(s) can be identified in mammalian tissue and cultured cells using endonuclease cleavage of RT-PCR products generated from "multi primers" (sense primer, degenerate oligonucleotide corresponding to a region of the first extracellular domain; antisense primer, degenerate oligonucleotide complementary to the second extracellular domain) that amplify the cytoplasmic loop regions of all known connexins except Cx36. In addition, we provide sequence information on RT-PCR primers used in our laboratory to screen individual connexins and predictions of extension of the "multi primer" method to several human connexins

Disminución de la viabilidad y capacidad de proliferación en líneas celulares de origen tumoral, por efecto de una desoxirribonucleasa / Decrease in vibility and proliferation ability of tumor cell lines by effect of a deoxyribonuclease

La desoxirribonucleasa (DNasa I) es una nucleasa, capaz de intervenir en la degradación y reparación de los ácidos nucleicos. También participa en la eliminación de células dañadas, envejecidas o neoplásicas activando los sistemas relacionados con la muerte celular programada (MCP). El fracaso para eliminar a las células neoplásicas por medio de la MCP, es debido entre otras cosas, a la disminución en la concentración o actividad de las nucleasas en este tipo de células, favoreciendo del desarrollo de la masa tumoral. En este estudio, se valoró la viabilidad y capacidad de proliferación de las siguientes líneas tumorales: CaLu-1, SK-MES-1, HeLa, HEp-2, L-929; y en las siguientes células normales: mononucleares totales de sangre periférica (MNTSP) de pacientes sin cáncer y en los fibroblastos fetales MRC-5. La DNasa I se dosificó sobre el cultivo celular a las siguientes concentraciones: 0.75, 1.5, 3.0, 6.0, y 9.0 µg/mL. Los resultados mostraron una correlación de dosis respuesta en la viabilidad y proliferación, con una pérdida en la viabilidad cercana al 100 por ciento para HeLa y HEp-2, y del 50 por ciento aproximadamente en CalU-1, SK-MES-1 y L-929, comparadas con MNTSP y fibroblastos MRC-5, que redujeron de un 10 a 14 por ciento sus valores a la cocentración más alta de DNasa I; en los resultados obtenidos al medir la proliferación celular, la tendencia fue similar en las líneas celulares a las concentraciones más altas de la nucleasa. Al valorar viabilidad y proliferación célular, se obtuvieron diferencias estadísticamente significativas (p < 0.05); al comparar los resultados obtenidos de células normales y líneas célulares de origen tumoral. La importancia de la DNasa I, como parte de un control fisiológico natural de la proliferación celular, como lo es la MCP, y los resultados obtenidos en este trabajo, nos permiten sugerir su posible utilización complementaria a la terapéutica tradicional en el tratamiento del cáncer

Técnicas, estrategias y usos de biología molecular en medicina / Techniques, strategies, and uses of molecular biology in mecidine

En el presente trabajo se describen parte de las técnicas de biología molecular que se utilizan en medicina. Actualmente las principales aplicaciones de estas técnicas son en el diagnóstico de enfermedades hereditarias, infecciosas y neoplásicas, así como en estudios de regulación de la expresión génica y en terapia con proteínas recombinantes. Con la aplicación de las técnicas de biología molecular en diversas áreas de la medicina, se abre también la posibilidad de poder realizar terapia génica en humanos

Chromosomal aberrations induced with endonucleases

Experimentos com endonuclease de Neurospora crassa, DNase I pancreático e endonucleases de restriçäo de bactérias indicam que quebras duplas na fita de DNA säo lesöes finais para a induçäo de aberraçöes cromossômicas, absorçäo pelas células de tais enzimas podem ser medidas por diferentes métodos, que säo discutidos aqui