Decay in intact DNA recovery in blood samples kept at room temperature.

Blood Samples were kept at room temperature for a period of 3-6 months at room temperature to know the amount of quantitative DeoxyriboNucleic Acid [DNA] recovery from these samples. We are able to recover good amount of DNA for about first 3-6 weeks after which the DNA is decreased drastically and after two months there hardly any chance of intact DNA recovery from these samples. It has been concluded that blood samples recovered from scene of crime after about 1-2 months is a waste. The samples must be recovered as early as possible to recover intact DNA from them. The samples must be collected within 1-2 months from scene of crime until and unless the climate is cold enough to increases decay time. This study is very useful for the investigating authorities which can make errors while collecting blood samples for DNA analysis.

Aspectos biomoleculares de la infección por el virus de la inmunodeficiencia humana / Biomolecular aspects of the human immunodeficiency virus infection

El presente artículo de revisión se centra en las consideraciones fundamentales sobre la biología molecular del virus de la inmunodeficiencia humana, el principal de los retrovirus que infectan a los hombres, destacando sus aspectos constitutivos así como genéticos y las alteraciones con la célula huésped. Se presenta además los aspectos morfofuncionales básicos de los linfocitos T CD4 y las interacciones que a nivel de membrana se producen para favorecer la infección por el virus y que explican su fisiopatología. Finalmente, se destacan los eventos intracelulares que conducen a la replicación y ensamblaje viral que producen la muerte celular y explican la inmunosupresión del huésped

Metilación del DNA / DNA methylation

El objetivo del presente artículo es revisar los conceptos actuales de mayor importancia que se vienen manejando sobre un tema que ha despertado gran interés en el estudio de la biología de los mecanismos asociados al DNA y a la expresión del gen. Se estudiará una modificación bioquímica de la larga cadena de nucleótidos, que ha sido llamada METILACION DEL DNA; analizando la manera como ocurre esta modificación; en qué sitios de la secuencia ocurre; en qué momento del ciclo celular y con qué frecuencia sucede; cuáles son los tipos de cambios que pueden presentarse; y, lo más relevante, cuál es el posible papel que cumple la metilación del DNA dentro de procesos genéticos y fenómenos patológicos humanos como el cáncer y el envejecimiento celular

Identification of schistosome-infected snails by detecting schistosomal antigens and DNA sequences

Cercarial shedding tests do not provide species identification of the shistosomes concerned and cannot detect prepatent schistosomal infections. We have demonstrated that both immunodetection by ELISA of schistosomal antigens in snail hemophlymph, and dot hybridization of snail extracts by DNA probe representing highly repeated sequences, proved suitable for detecting infected snails during prepatnecy as well as patency. A group-specific monoclonal antibody was found to be suitable for detecting Schistosoma mansoni infection in Biomphalaria sp., but not for positive identification of S. haematobium in Blulinus sp. Comparative evaluation of the diagnostic qualities, and technical aspects and cost of these tests, point to the superiority of the immunodetection approach for large scale detection of snails prepatently infected with S. mansoni. This approach is potentially useful for providing extended information on schistosome-snail epidemiology that may facilitate rapid evaluation of the danger of post-control reinfection, and help make decisions on the time and place of supplementary control measures. In this context the potential usefulness of the immunodetection or DNA probing approach for facilitating catalytic model representation of schistosome-snail epidemiology warrants further evaluation. Specific identification of S. haematobium in Bulinus by either of these approaches may be possible depending on the development of suitable antibodies or DNA probes

value of chromosomal studies in diagnosis, prognosis and DNA-characterization in lymphomas

The study included patients with lymphoma with different ages and sexes, in order to single out the findings of chromosomal aberrations that could be taken as diagnostic and/or prognostic marker and it can help in DNA characterization and probe synthesis. The following studies were carried out: [a] History and clinical examination, [b] lymph node biopsies for histopathological examination, [c] chromosomal analysis for cultured lymph node tissue and peripheral blood lymphocytes before and after treatment using G-banding technique. According to the clinical and histopathological diagnosis patients were enrolled into two groups. G1 included patients with different histologic types of Hodgkin's lymphoma [HL]. G2 included patients with different histologic types of non-Hodgkin's lymphoma [NHL]. The results of chromosomal studies were analyzed in correlation with the histopathological classification: In HL the number of chromosomes differ with the histologic type and the detection of certain chromosomal aberrations which are non-clonal; in NHL clonal chromosomal abnormalities which are recurring and consistent with specific histologies; the data pointed to the value of chromosomal analysis of the points of break and translocation in DNA characterization of oncogenesis and in prognosis

DNA sequence amplification in sciarid flies: results and perspectives

The discovery of Dna sequence amplification in sciarid flies and investigations into its control and biological significance are reviewed. Results thus far show that amplification of specific salivary gland polytene chromosome bands is a general phenomenon in sciarids. It brought about as part of a final endoreplication cycle by the rising titer of ecdysterone that occurs as the Larvae approach the prepupal period. Amplification and transcription of these bands is a late, multistep effect of this hormone.The Dna puffs which form in amplified region produce mRNAs which are translated into polypeptides that appear to be involved in coccon formation. Application of molecular cloning techniques to the study of Dna amplification has allowed precise quantitation of amplification for several Dna puffs and is yielding maps of their transcription units.These techniques will ultimately help to define the origins of Dna puff replication and contribute to an understanding of the mechanism and control of the amplification phenomenon in sciaridae. Projections for future experimental approaches are presented