Frecuencia de la mutación 185delAG en el gen BRCA1 en mujeres chilenas sanas con antecedentes familiares de cáncer de mama / Frequency of the 185delAG mutation in the BRCA1 gene in chilean healthy women with family history of breast cancer

Background: Breast cancer is the most common malignancy among women, and is the second cause of cancer mortality among Chilean women. Female mortality due to breast cancer in Chile has shown a steady increase from 9.5 deaths per 100.000 women in 1985 to 12.8 deaths per 100.000 in 1995. A family history of breast cancer is one of the main risk factors for the development of the disease. BRCA1 and BRCA2 are two major hereditary breast cancer susceptibility genes. Mutations in these genes are associated to inherited breast cancer; 664 predisposing mutations have been described, but in specific populations only some of them, such as 185delAG have been found to be associated with susceptibility to breast cancer. Aim: To establish the frequency of the 185delAG mutation in the BRCA1 gene in Chilean healthy women with a family history of breast cancer. Patients and Methods: The 185delAG mutation was studied by mismatch polymerase chain (PCR) reaction in 382 Chilean healthy women with at least two relatives affected with breast cancer. The PCR products were digested with the restriction enzyme HinfI. Digestion of the normal allele (170 pb fragment) produces a 150 pb fragment; the PCR product for the mutant allele does not contain a site for HinfI and therefore remains as a 170 bp fragment after digestion. Results: One of the 382 healthy women presented the fragment of 170 pb after digestion with HinfI suggesting that she was heterozygous carrier for this mutation. The mutant patient had a mammography without suspicion of cancer. Conclusions: The frequency of the 185delAG mutation in BRCA1 was 0.26 percent (1/382) in Chilean healthy women with a family history of breast cancer

Aislamiento de enterococcus faecium resistente a vancomicina con genotipo vanB en el Hospital Clínico Regional de Concepción / Isolation of vancomycin resistant enterococcus faecium with genotype vanB at the Hospital Clínico Regional de Concepción

La resistencia bacteriana a los agentes antimicrobianos ha aumentado durante las últimas décadas. De particular importancia es la descripción de aislamientos de Enterococcus resistente a vancomicina (EVR), de reciente y progresiva descripción en nuestro país. Comunicamos el aislamiento de dos cepas de E. faecium resistentes a vancomicina de pacientes colonizados por este microorganismo en el Hospital Clínico Regional de Concepción. El estudio feno y genotípico fue positivo para vanB, además ambos aislamientos presentaron similitud genética en un estudio de tipificación molecular por rep-PCR. Interesantemente el aislamiento de estas cepas precedió al aislamiento de EVR según el protocolo ministerial. Esta diferencia puede explicarse por los factores de riesgo que presentaron los pacientes estudiados

Estudio clínico molecular de pacientes chilenas con síndrome de McCune-Albright / Clinical and molecular study of Chilean patients with McCune-Albright Syndrome

Background: McCune-Albright Syndrome (MAS) is characterized by precocious puberty, "cafe au lait" skin lesions and polyostotic fibrous dysplasia. It is caused by 4 post-zygotic mutations of Gas protein with a mosaic distribution. Aim: To describe the clinical presentation and to investigate the presence of the Arg by his substitution (R201H) in 14 girls with MAS. Patients and methods: We performed a clinical analysis of the patients and specific allele PCR in DNA obtained from leukocytes. Results: Twelve of 14 patients presented with precocious puberty, one with cyclical vaginal bleeding and one with pathological bone fractures. Eight girls had polyostotic fibrous dysplasia, one had hyperthyroidism, four had pathological fractures, ten had ovarian cysts, six had breast hyperpigmentation and ten had "cafe au lait" skin lesions. We detected the R2O1H mutation in 10 of 14 patients. We found no difference in the severity of symptoms or in the age of presentation between the patients with and without the mutation. Conclusions: The R201H mutation can be detected in white blood cells, in approximately 70 per cent of cases. Patients exhibit wide clinical variability with the same molecular defect. This suggests that tissues have different proportions of mutant cells

Aislamiento de genes carotenogénesis de xanthophyllomyces dendrorhous (ex. phaffia rhodozyma) mediante PCR / Isolation of carotenogenesis genes of xanthophyllomyces dendrohous (ex. phaffia rhodozyma) through PCR

Xanthophyllomyces dendrorhous (ex.phaffia rhodozyma) es una levadura basidiomicetica carotenogénica, en la cual aspectos importantes de su biología como la organización general de su genoma, número de cromosomas y nivel de ploidia aún no son completamente entendidos. En atención a esto, se han orientado esfuerzos en estudios moleculares con el objetivo de aumentar el conocimiento de su genética. En el presente trabajo, se describe un eficiente procedimiento para seleccionar y clonar genes a partir de una genoteca de DNA genómico de x. dendrorhous mediante la amplificación de DNA por PCR, utilizándo parejas de partidores específicos para el gen crtl. Adicionalmente, se describe la síntesis de cDNA a partir de RNA total de la levadura mediante transcripción reversa acoplada a amplificación de DNA (rt-pcr)

Caracterización clínico molecular de la enfermedad granulomatosa crónica autosómica recesiva causada por déficit de p47-phox / Clinical and molecular characterization af autosomal recessive chronic granulomatous disease caused by p47-phox deficiency

Background: The cytosolic protein p47-phox (phagocyte oxidase) is one of the essential components of the superoxide generating system in phagocytes and its defect causes approximately 30 percent of the chronic granulomatous disease (CGD) cases. Aim: Two patients were studied, belonging to the same family, without a consanguinous background, in which deficiency or absence of superoxide generation was found together with recurrent and severe infections in one case and benign infections in the second. Methods: The presence of gp91-, p67- and p47-phox in patients and controls was determined by Western Blot analysis of granulocytes. Sequencing of PCR amplified DNA was performed by an enzimatic method. Results: Western Blot analysis showed normal expression of gp91 and p67 and absence of p47-phox. The molecular genetic study demonstrated a homocygotic dinucleotide GT (GT) deletion at the beginning of exon 2 of the p47-phox gene. The same mutation has been found in European, American and Japanese patients. Conclusions: The molecular characterization of this pathology done for the first time in Chile is important for diagnostic classification, patient prognosis, and adequate genetic advice and a possible future therapy

Asociación entre el fenotipo fisura labiopalatina no sindrómica y marcadores de microsatélite ubicados en 4q / Association between nonsyndromic cleft lip/palate with microsatellite markers located in 4q

Background: Nonsyndromic cleft lip with or without cleft palate (NSCLP) is a common craniofacial defect. Association studies have suggested that a cleftinglocus is located on chromosome 4q at or near two microsatellite markers D4S175 and D4S192. Aim: To test the hypothesis on the possible presence of a clefting locus on chromosome 4q. Material and methods: We carried out an association study on a sample of unrelated NSCLP patients, of their unaffected relatives and in controls. Both probands and relatives were further analyzed depending if they originated from simplex or multiplex families. DNA was analyzed with two PCR markers close to the putative NSCLP locus, dinucleotide repeats D4S175 and D4S192. PCR products were resolved by PAGE and visualized by silver staining. Statistical analysis was performed by means of c2 log ratio. Results: Significant differences between NSCLP and controls were observed when comparing the allele frequency distribution of D4S192 both in the total sample as well as in NSCLP-multiplex and simplex cases. No significant differences for D4S175 were observed in any of the comparisons. Unaffected relatives showed significant differences with controls both for D4S175 and D4S192. Conclusions: Our results support the hypothesis that a NSCLP locus maps on chromosome 4q close to the microsatellite marker D4S192. No differences were observed between NSCLP multiplex and simplex cases versus controls, implying that they do not represent different etiologic entities. The results of the present and previous studies in the same group of patients support the hypothesis that several major interacting genes participate in the etiology of NSCLP

PCR-based diagnosis of a case of herpetic whitlow in an AIDS patient

As infeccoes herpeticas sao complicacoes comuns em pacientes com AIDS. As manifestacoes clinicas podem ser incomuns e o tratamento antiviral e imperativo. Um metodo diagnostico rapido pode prevenir abordagens e tratamentos incorretos. A reacao em cadeia da polimerase (PCR) e um metodo rapido, sensivel e especifico para a amplificacao de DNA e para o diagnostico de doencas infecciosas, especialmente as de etiologia viral. Esta abordagem tem vantagens quando comparada com os metodos convencionais de diagnostico virologico. Recentemente nos relatamos um novo protocolo de PCR para o dignostico rapido de infeccoes herpeticas com supressao da etapa de extracao de DNA. Neste trabalho nos apresentamos um caso de paroniquea herpetica com diagnostico atraves de PCR especifico para Herpes Simplex tipo 1 usando o referido protocolo

Detection of HTLV-I antibodies and DNA in blood sample of a patient with myelopathy in Nigeria

Descrevemos um caso de infecçäo por HTLV-I associado a mielopatia, em mulher de 50 anos, na Nigeria. A paciente apresentou fraqueza progressiva dos membros inferiores e posteriormente incapacidade para andar. A presença de anticorpo HTLV-I no plasma coletado da paciente foi repetidamente detectada pelos ensaios imunoenzimaticos (Abbott HTLV-I EIA e Coulter SELECT-HTLV I/II) e confirmada pela tecnica de Western Blot. Adicionalmente amplificou-se o DNA do HTLV-I a partir do DNA genomico isolado das celulas mononucleares do sangue periferico da paciente através da técnica de PCR. Este achado e significativo sendo o primeiro relato de associaçäo de HTLV-I com mielopatia, na Nigeria

Amplificación de genes bacterianos con reacción de polimerasa en cadena (PCR) para la detección de invasión microbiana de la cavidad amniotica (IMCA) y predicción de parto prematuro / Amplification of bacterial genes with polimerase chain reaction (PCR) for the detection of microbial invasion of amniotic cavity and prediction of premature labor

Se realizaron PCR y cultivos en líquido amniótico (LA) obtenido por amniocenteáis en 50 embarazadas con trabajo de parto prematuro sin rotura de membranas, y en 13 pacientes con embarazo de término, sin trabajo de parto, en quienes se realizó amniocentesis para evaluar madurez pulmonar fetal antes de la interrupción electiva de la gestación. Las pacientes fueron controladas hasta la resolución del embarazo. Se determinó el valor diagnóstico de los exámenes para predecir parto prematuro y complicaciones neonatales. PCR fue positivo en 23 casos, siendo E coli el germen más frecuentemente detectado (13). El cultivo fue positivo en 6 casos, coincidiendo el germen con PCR en 4 de ellos. La evolución a parto prematuro fue diferente entre los grupos PCR + y PCR-. PCR demostró sensibilidad mayor que los cultivos (40 vs 13 por ciento), y especificidad menor (45 vs 90 por ciento) para predecir parto prematuro menor a 37 semanas. La sensibilidad y especificidad para predecir parto prematuro menor a 34 semanas resultó aún mayor (64 y 59 por ciento, respectivamente). Ninguna de las 13 pacientes de término, candidatas a operación cesárea electiva, resultó positiva para PCR o cultivo

Queratitis herpética: correlación clínico-virológica / Herpetic keratitis: clinic-virological correlation

Patients and methods: Forty one patients with a clinical diagnosis of herpetic keratitis were studied. Viral isolation, polymerase chain reaction (PCR) and typification were done in a sample taken by swabbing the ocular lesion. Results: Twenty six patients (31 percent female) had epithelial keratitis, that was mild or moderate in 88 percent of cases and acute in 77 percent of them. In 20 patients (77 percent), viral isolation and PCR were positive (HSV-2 in one case). Fiften patients (67 percent female) had stromal keratitis, 93 percent of cases were moderate or severe and 53 percent were acute. Viral isolation was negative in all cases and in 20 percent PCR was positive. Conclusions: Viral isolation and PCR were equally sensitive in epithelial keratitis, but in stromal keratitis only PCR could detect the virus. Moderate acute dendrite was the predominant clinical manifestation. The higher proportion of women with stromal keratitis supports is possibly autoimmune etiology). HSV-2 is seldomly isolated and possibly associated to vertical transmission

Identificaçäo rapida de mycobacterium spp. a partir de amostras clinicas / Fast identification of Mycobacterium spp. obtained from clinical samples

Avaliou-se a PCR no diagnostico laboratorial de infeccao por Mycobacterium spp. utilizando diversas amostras clinicas. Classificou-se os grupos segundo criterios clinicos, radiologicos e epidemiologicos em: infeccao comprovada, altamente provavel, os grupos controle negativo com infeccao por outras bacterias, e controle negativo sem infeccao. Padronizou-se o tratamento de amostras e extracao de DNA nos diversos fluidos biologicos. A amplificacao do DNA foi realizada em duas etapas: a primeira utilizou-se iniciadores especificos para o Genero Mycobacterium e a segunda utilizou-se iniciadores especie especificos para o complexo M. tuberculosis e M. avium. A PCR apresentou cem por cento de positividade para o grupo controle positivo, o grupo de estudo com alta probabilidade de infeccao apresentou cultura e baciloscopia de 43,6 32,1 por cento de positividade respectivamente, a PCR a presentou 88,5 por cento de positividade. O grupo provavel teve positividade na cultura e baciloscopia de 21,05 e 16,8 por cento respectivamente, e a PCR foi de 61,5 por cento. Nenhum caso de falso positivo foi encontrado nos grupos controles negativos. Conclui-se que o metodo de PCR e efetivo, reprodutivel, sendo aplicavel na rotina laboratorial

Alteraciones moleculares de oncogenes en tumores intracraneales / Molecular alterations of oncogenes in brain tumors

Se analizaron 27 tumores intracraneales utilizando sondas moleculares específicas para detectar a los genes CMYC, NMYC y NRAS. Hemos encontrado un importante porcentaje de alteración para estos oncogenes (amplificación y/o rearreglo). Para el oncogen CMYC detectamos el 55 porciento de alteración, 40 porciento para NMYC y el 40 porciento para genes relacionados a RAS. En este estudio fueron incluidos tumores de diferentes diagnósticos histopatológicos en los cuales se detectaron alteraciones combinadas de los genes C y NMYC; este patrón de alteración en la misma muestra tumoral no había sido reportado anteriormente. Además, hemos detectado una alteración frecuente de los genes RAS en adenomas, presentándose amplificación génica así como una expresión incrementada de los mismos. Estos resultados sugieren un papel importante de los genes CMYC, NMYC y RAS en el desarrollo de tumores intracraneales.