Progress on DNA quantification in estimation of postmortem interval / 法医学杂志

Estimation of postmortem interval (PMI) is one of the difficult problems in forensic medicine. With the development of molecular biological techniques, DNA quantification methods were widely applied in estimating PMI. The postmortem degradation of DNA in different tissues and organs was discussed in this article and the recent DNA quantitative techniques being used for estimating PMI were reviewed. These techniques included single cell gel electrophoresis, Feulgen staining image analysis, flow cytometry.

L-Carnitine ameliorates the iron mediated DNA degradation in peripheral leukocytes of beta-thalassemic children

Iron overload is a common complication in beta-thalassemia that induces intracellular oxidative stress producing lesions in the DNA including double strand breaks. The aim of this study was to evaluate DNA damage in peripheral leukocytes of-thalassemic children and to investigate its association with the iron overload and the role of L-carnitine therapy upon this damage. Fifty beta-thalassemic children [25 TM and 25 TI] with 20 age and sex matched apparently healthy children [control group] were included. Serum ferritin level was measured by ELISA. DNA damage was evaluated by the Gel electrophoresis to determine the total DNA genomic damage [TGD]. The intensity of DNA nucleoprotein was measured by software Gel Pro analyzer computer program as maximum optical density [max.OD] values of apoptotic fragments of DNA at 200bp, 400bp and 600bp. The smear shape pattern on gel electrophoresis and Pro-Gel analyzer chart indicating double strand breakage of the DNA was detected in 76% of the thalassemic children. The thlassemic patients [the whole group and each of TM and TI groups] had significantly higher prevalence of DNA double-strand breaks in their leukocytes with significant higher values of max. OD at 200,400and 600 bp compared to the control group. The thalassemic children on regular L-carnitine therapy [50 mg/kg/d for at least 6 months] had significantly lower prevalence and degrees of DNA breaks [TGD] with significant lower max. OD values at 200,400 and 600 bp compared to those not on L-carnitin therapy. There was significant positive correlation between the mean serum ferritin levels and the values of max. OD at 200 and 400bp. The data obtained from the Roe Curve shows that, the best sensitivity of 95% and specificity of 75% for the mean serum ferritin were at the cut off point of 820 ng/ml to predict the ocurrence of TGD in thalassemic leukocytes. Thalassemic children had significant DNA double-strand breaks in their leukocytes that was positively correlated to their iron overload reflected by serum ferritin level and can be ameliorated by L-carnitine supplementation

Buccal cells submitted to three different storage conditions before DNA extraction

This study evaluated quantitatively and qualitatively the effect of the storage time of samples before the application of the cell lysis solution (CLS) for extracting DNA from buccal cells (BC). BC from the upper and lower gutter region were collected from 5 volunteers using special cytobrushes (Gentra), totaling 3 collections for each individual. In the control group (n=10), CLS was applied soon after BC collection. In the other two groups, samples were stored at room temperature (n=10) or at 4°C (n=10). After CLS application, DNA was extracted according to the manufacturer's instructions (Puregene DNA Buccal Cell Kit; Gentra Systems, Inc.). The DNA obtained was evaluated by two calibrated blind examiners using spectrophotometry and analysis of DNA bands (0.8 percent agarose gel electrophoresis). The obtained data were submitted to one-way ANOVA. The means and standard deviations for DNA extracted under immediate, room temperature and cooling temperature conditions were 3.5 ± 0.7, 3.0 ± 0.6 and 4.1 ± 1.8 µg, respectively (p=0.385). No significant differences were found in relation to the amount of DNA for the different storage conditions. However, in the visual analysis of the DNA bands, no trace of DNA degradation was detected when CSL was applied soon after DNA collection, while DNA bands with degradation could be observed in the other groups. Within the limitations of the study, it may be concluded that CLS should be applied soon after DNA collection in order to obtain high-quality DNA from BC.

Estudio de las modificaciones de la via apoptótica mediada por ceramidas en la carcinogenesis inducidas de glándula parotida / Study of the modifications of the apoptotic route mediated by ceramides in the carcinogenicity induced of parotid gland

La apoptosis o muerte celular programada es un proceso fisiológico normal que conduce a la remoción de las células mutadas o dañadas. La apoptosis se ha relacionado con la patogénesis del cáncer ya que las células malignas evaden los mecanismos apoptóticos. La glándula parótida es el sitio más común de tumores de glándulas salivales y solo el 15 % es detectado en estadios tempranos. Conocer que ocurre con las moléculas involucradas en el mecanismo de apoptosis para así poder ser utilizadas como biomarcadores y en la restauración de vías apoptóticas alteradas, resultaría de suma importancia para la aplicación de nuevas terapias y de terapias de prevención en los pacientes con tumores de cabeza y cuello. El objetivo de este trabajo fue estudiar las alteraciones tempranas de la vía apoptótica inducida por Fas, mediada por ceramidas en el proceso de tumorogénesis experimental. Para realizar este estudio, se utilizaron ratas machos, a las que se les inyectó 0,05 ml de 9, 10- dimethyl 1, 2 benzanthracene (DMBA) disuelto en acetona, en cada glándula parótida. Las muestras fueron analizadas a los 7; 30; y 150 días post tratamiento. Se realizó coloración de H/E, PAS y ATO, inmunocitoquímica para Fas por streptavidina–biotina, determinación de ceramidas por inmunofluorescencia, ladder de ADN y amplificación y secuenciación del los exones 3 y 4 del gen fas.

Recent advancement in miniSTR research / 法医学杂志

As the most popular and important inherited marker used in forensic identification, short tandem repeat (STR) always have partial DNA profiling or even no results when handling degraded or minute DNA sample. Through redesigning primers close to STR core repeats, MiniSTR can access shorter STR loci and increase success rate of DNA profiling in degraded or minute DNA sample. The review provides an update on the advancement of miniSTR research to give information in the practice of forensic science.

A reviewing for profiling of highly degraded remains / 法医学杂志

It's always a challenge to type from highly degraded biological remains. PCR-based STR genotyping is helpful and valuable for such degraded samples like bones, teeth et al, but the typing results are sometimes unstable or wrong. Here the methods for solving the problems and improving reproducibility are reviewed.

Correlative analysis on the relationship between PMI and DNA degradation of cell nucleus in human different tissues / 华中科技大学学报（医学）（英德文版）

To determining the postmortem interval (PMI) through quantitative analysis of the DNA degradation of cell nucleus in human brain and spleen by using image analysis technique (IAT). The brain and spleen tissues from 32 cadavers with known PMI were collected, subjected to cell smear every 1 h within the first 5-36 h after death, stained by Feulgen-Van's staining, Three indices reflecting DNA in brain cells (astrocytes) and splenic lymphocytes, including integral optical density (IOD), average optical density (AOD), average gray (AG) were measured by employing the mage analysis instrument. The results showed that IOD and AOD declined and AG increased with the prolongation of dead time within 5-36 h. A correlation between the PMI and gray parameters (IOD, AOD and AG) was identified and the corresponding regression equation was obtained. The parameters (IOD, AOD and AG) were proved to be effective quantitative indicators for accurate estimation of PMI within 5-36 h after death.