Molecular gate keepers succumb to gene aberrations in colorectal cancer in Kashmiri population, revealing a high incidence area

Colorectal cancer [CRC] is one of the leading malignancies worldwide and has been reported to show geographical variation in its incidence, even within areas of ethnic homogeneity. The aim of this study was to identify p53 and K-ras gene mutations in CRC patients in a Kashmiri population, and to assess whether these mutations are linked with clinicopathological parameters. Paired tumor and normal tissue samples from a consecutive series of 53 patients undergoing resective surgery for CRC were prospectively studied for p53 and K-ras gene mutations by PCR/single strand conformation polymorphism [SSCP]. Less than half [45%, 19/42] of the patients presented mutations in the p53 gene. Twenty eight mutations were found in the p53 gene, which comprised of 23 substitutions [17 transitions + 6 transversions], and five insertions. The 23 substitutions constituted 18 missense mutations, two nonsense mutations, and three silent mutations. Of the 28 mutations [7.14%] observed in this study, 2 were not previously reported for CRC samples and were identified as novel p53 mutations. A few patients [22.64%, 12/53] presented with mutations in K-ras, constituting 13 missense mutations, out of which 11 were G-A transitions, one was a G-C transversion, and one a G-T transversion. More than half [61.5%] of the mutations occurred in codon 12 whereas a few [38.5%] occurred in codon 13. One tumor contained missense mutations in both codons. Comparison of the mutation profiles of our patients with those of other ethnic populations and regions reflected both differences and similarities, indicating co-exposure to a unique set of risk factors. Mutations of the p53 and K-ras genes are some of the most common genetic changes in the development of human CRC. The high frequency of p53 gene mutations implicates p53 as a predominant factor for CRC in the high-risk ethnic Kashmiri population

Improved diagnosis of central nervous system tuberculosis by MPB64-Target PCR / Diagnóstico da tuberculose do sistema nervoso central por MPB64-Target PCR

Central nervous system (CNS) tuberculosis is a serious clinical problem, the treatment of which is sometimes hampered by delayed diagnosis. Clearly, prompt laboratory diagnosis is of vital importance as the spectrum of disease is wideand abnormalities of the cerebrospinal fluid (CSF) are incredibly variable. Since delayed hypersensitivity is the underlying immune response, bacterial load is very low. The conventional bacteriological methods rarely detect Mycobacterium tuberculosis in CSF and are of limited use in diagnosis of tuberculous meningitis (TBM). This double blind study was, therefore, directed to the molecular analysis of CNS tuberculosis by an in-house-developed PCR targeted for amplification of a 240bp nucleotidesequence coding for MPB64 protein specific for Mycobacterium tuberculosis. Based on the clinical criteria, 47 patients with CNS tuberculosis and a control group of 10 patients having non-tubercular lesions of the CNS were included in the study. Analyses were done in three groups; one group consisting of 27 patients of TBM, a second group of 20 patients with intracranial tuberculomas and a third group of 10 patients having non-tubercular lesions of the CNS acted as control. There were no false positive results by PCR and the specificity worked out to be 100 percent. In the three study groups, routine CSF analysis (cells and chemistry), CSF for AFB smear and culture were negative in all cases. PCR was positive for 21/27 patients (77.7 percent sensitivity) of the first group of TBM patients, 6/20 patients (30 percent sensitivity) of the second group with intracranial tuberculomas were positive by PCR and none was PCR-positive (100 percent specificity) in the third group. Thus, PCR was found to be more sensitive than any other conventional method in the diagnosis of clinically suspected tubercular meningitis.

A tuberculose do sistema nervoso central (CNS) é um problema clínico sério, cujo tratamento é dificultado pelo diagnóstico tardio. O diagnóstico laboratorial rápido é de importância vital considerando que o espectro da doença é amplo e as anormalidades do liquor são muito variáveis. Considerando que a hipersensibilidade tardia é a resposta imune fundamental, a carga bacteriana é muito baixa. Os métodos bacteriológicos convencionais raramente detectam Mycobacterium tuberculosis no liquor e são de uso limitado para diagnóstico da meningite tuberculosa (TBM). O presente estudo duplo-cego objetivou a análise molecular da tuberculose do CNS através de um PCR desenvolvido in-house direcionado para a amplificação de uma seqüência de nucleotídios de 240pb que codificam a proteína MPB64 especifica de Mycobacterium tuberculosis. Baseando-se em critérios clínicos, selecionou-se 47 pacientes com tuberculose do CNS e um grupo controle de 10 pacientes com lesões não-tuberculosas no CNS. As análises foram divididas em três grupos: um grupo de 27 pacientes com TBM, um segundo grupo com 20 pacientes com tuberculomas intracraniais e um terceiro grupo de 10 pacientes com lesões não-tuberculosas no CNS (controles). O PCR não forneceu nenhum resultado falso-positivo, com 100 por cento de especificidade. Em todos os três grupos de estudo, os resultados das análises de rotina do liquor por histologia, química e baciloscopia e também cultura foram negativos em todos os casos. No primeiro grupo de pacientes com TBM, PCR foi positivo em 21/27 pacientes (sensibilidade de 77,7 por cento). No segundo grupo de pacientes com tuberculomas intracraniais, 6/20 foram positivos (sensibilidade de 30 por cento). Nenhum dos pacientes do grupo controle foi positivo (100 por cento de especificidade). Dessa forma, o PCR mostrou-se mais sensível que os métodos convencionais no diagnóstico de casos suspeitos de meningite tuberculosa.