Application of the Peak Area Ratio of STR Loci to Amelogenin Locus in the Esti-mation of DNA Degradation / 法医学杂志

Objective To explore the change rules of peak area ratio of STR loci to Amelogenin (AMEL) locus (STR/A M EL ), a sex-determ ining gene in DNA degradation, and to evaluate the application of STR/A MEL value in the estim ation of DNA degradation degree. Methods DNA w as extracted from iliopsoas, and the variations of STR/A MEL value (Penta E/AMEL, Penta D/AMEL, FGA/AMEL) w ere analyzed after the artificial degradation w as m ade by DNaseⅠ, and the changes of these three ratios of the iliopsoas naturally degraded in an outdoor environm ent w ere also analyzed. The regression curves w ere analyzed using the periods of DNA degradation and outside the body as the independent variable (x) and the STR/A MEL value as the dependent variable (y) and three curve equations under tw o conditions w ere established. Results B oth under the conditions of artificial and natural degradation, STR/A MEL value had a negative relationship w ith the degradation tim e. The relationship betw een STR/A MEL and degradation tim e can be w ell sim ulated by the cubic function. R2 w as over 0.99 under controlled degradation condition and over 0.86 under natural degradation condition. Conclusion The STR/A MEL value (Penta E/AMEL, Penta D/AMEL , FGA/AMEL ) is negatively related w ith the DNA degradation degree, w hich follow s m athem atical regression m odels strictly, and it m ight be applied to evaluate the DNA degradation degree.

Analysis of antibacterial activity and mechanism of polypyridyl ruthenium complex / 中国药理学通报

Aim To analyze the antibiotic activity and mechanism of a polypyridyl ruthenium complex. Meth-ods The antibacterial activity of [ ( Phen ) 2 Ru ( dp-pz) ] ( PF6 ) 2 was determined by MIC and MBC value. Based on a fluorescent activity of this complex, the flu-orescent emission spectra was used to analyze the com-bination of complex to DNA. Then the competition combination was analyzed between complex and Gold View to DNA. Lastly, gel electrophoresis of DNA was applied to detect the combination situation between complex and DNA. Results This kind of polypyridyl ruthenium complex showed a significant antibacterial activity with a minimum antibacterial conentration of 0. 2~0. 4 g · L-1 . That was caused by the combina-tion and distortion of DNA due to the activity of this complex. Conclusion The antibacterial activity and the mechanism of antibacterial activity about [ ( Phen) 2 Ru( dppz) ] ( PF6 ) 2 are confirmed in this re-search, which provides a good foundation for the devel-opment of such class of compound.

Vibrio vulnificus induces acute necrosis of dendritic cells via toll-like receptor 2 and 4 pathways / 中华传染病杂志

Objective To explore how Vibrio vulnificus (Vv) invades dendritic cells (DC) and induces acute necrosis of DC via toll-like receptor (TLR) 2 and 4 pathways.Methods Vv 1.1758 strain and DC 2.4 mixed culture model was established,observed the infection rates of DC with optical microscope,the location of Vv and structural changes of DC by transmission electron microscope.The expression levels of TLR2 and TLR4 mRNA were determined by real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR) and tumor necrosis factor-α (TNFα) protein titers were measured by enzyme-linked immunosorbent assay (ELISA).DNA ladder qualitative test was used to detect cell apoptosis,while flow cytometry was used to quantify cell apoptosis and necrosis rates.Statistical analysis was done by chi-square test and one-way ANOVE.Results The infection rates of DC after 0.5,1,2,4 and 6 h of mixed culture were (7.8±0.8) ％,(13.9± 1.1) ％,(34.6±4.9) ％,(77.8± 10.2)％ and (95.8 ± 13.1)％,respectively.Vv was generally located in the internal cell membrane of DC 2.4.After 2 h co-culture,nuclear chromatins of DC became active and intranuclear apoptosis bodies appeared.After 4 h,cytoplasmic vacuoles appeared,chromatin gathered,and cell membranes were seriously damaged.After 6 h,mitochondria was highly swelled and distorted,and cell apoptosis and necrosis occurred.TLR2 and TLR4 mRNA levels reached peak values after co-culture for 0.5 h; TNF-α level began to increase at 1 h (P＜0.05) and reached peak values at 2 h.DNA Ladder electrophoresis presented scouring necrosis after 2 h culture and apoptotic bands appeared between 720 bp and 900 bp after 4 to 5 h culture.Early apoptosis rates of DC after 2,4 and 6 h culture were (3.1±3.8)％,(7.8±4.7)％ and (12.7±8.2)％,and necrosis rates of DC were (16.7±12.5)％,(41.6±25.9)％ and (75.5±33.6)％,higher than that of control group (all P＜0.05).Conclusions Vv infects DC and induce DNA degradation through up-regulated expression of TLR2 and TLR4 and increasing of TNF-α inflammatory mediators.During cell degradation,apoptosis and necrosis coexist,while necrosis is predominant.

Comparison of the DNA Preservation in Neutral-Buffered Formalin Fixed Paraffin-Embedded Tissue and in Non-Buffered Formalin Fixed Paraffin-Embedded Tissue

BACKGROUND: The preservation of optimized DNA and its extraction from formalin-fixed, paraffin-embedded (FFPE) tissues are important issues. There has been some doubt over whether 10% neutral-buffered formalin is an ideal fixation solution for DNA preservation over non-buffered formalin, as conventionally recommended. In this study, the correlation between the efficiency of DNA extraction from FFPE tissues and buffered formalin was evaluated. METHODS: Several tissues with same conditions except fixatives were fixed in four different formalin solution groups and were routinely processed as paraffin-embedding protocols. DNAs were extracted from four different FFPE tissues that were stored for over 3 months and over 9 months. The quantity and quality of the DNAs were assessed with a NanoDrop ND-1000 spectrophotometer, and the polymerase chain reaction (PCR) amplification and degradation were analyzed via microchip electrophoresis. KRAS mutation analysis and microsatellite instability (BAT25) PCR were performed with each sample. RESULTS: The results showed no remarkable difference in the four groups. CONCLUSIONS: The study findings demonstrate that DNA preservation is fairly unaffected by a neutral buffer where there is short formalin manufacture period and an adequate formalin fixation time before embedding in paraffin.

DNA degradation by aqueous extract of Aloe vera in the presence of copper ions.

The plant Aloe vera has long been used in medicine, as dietary supplements and for cosmetic purposes. Aloe vera extracts are a rich source of polyphenols, such as aloin and aloe emodin and have shown a wide range of pharmacological properties, including anti-inflammatory and anti-cancer properties. The bioactive component aloe emodin has been reported to induce apoptosis in various cancer cell lines. Many of the biological activities of Aloe vera have been attributed to its antioxidant properties. However, most plant-derived polyphenols that are also present in Aloe vera may exhibit pro-oxidant properties either alone or in the presence of transition metals, such as copper. Previous reports from this laboratory have implicated the pro-oxidant action as one of the mechanisms for their anti-cancer properties. In the present paper, we show that aqueous extract of Aloe vera is also able to cause DNA degradation in the presence of copper ions. Further, the extract is also able to reduce Cu(II) to Cu(I) and generate reactive oxygen species, such as superoxide anion and hydroxyl radicals in a dose-dependent manner, which correlates with ability of the extract to cause DNA breakage. Thus, the study shows that in addition to antioxidant activity, Aloe vera extract also possess pro-oxidant properties, leading to oxidative DNA breakage.

Relationship between DNA of Rat Kidney and Post by Comet Assay / 中山大学学报(医学科学版)

[Objective] To study the correlation between kidney cell DNA degradation and postmortem interval within the span of 6-48 hour after the subject rats′ death.[Methods] To select 18 healthy mature female SD rats and equally divide them into 6 groups.To execute the rats with cervical spine articulation and put the rats under the incubator temperature of 25.1℃ (the average temperature of the 5 previous Decembers in Guangzhou prefecture).Sample kidney tissue from the rat separately 0 hour,6 hours,12 hours,24 hours,36 hours,48 hours,and 60 hours after the rats′ execution to prepare monoplast suspension,which is committed to comet assay.The comet images were captured by fluorescence CCD.Kinetic Comet 4.0 software was used to analyze images.Relevant data were collected by kinetic Comet 4.0 software and were subjected to Kruskal-Wallis test.[Results] Within the postmortem interval of 6-48 h,the number of SD rat kidney cell DNA fragments increased as the postmortem interval lengthens.So did the comet tail length.The Oliver tail moment and tail DNA of comet also showed sign of increase in positive proportion to the postmortem interval (their values corresponding to 60-hour-postmortem-interval were not obtainable.Kruskal-Wallis test indicated:the discrepancies of TL among the 6 groups were all significant (P ＜ 0.01).The difference of TM between 6 h group and 12 h group was not significant (P ＞ 0.05).The difference of TM between 24 h and 36 h was significant (P ＜ 0.05).The difference of TDNA among 6 h,12 h,and 36 h groups were not significant (P ＞ 0.05).The difference of TDNA between 36 h and 48 h was significant (P ＜ 0.05).[Conclusion] Degradation of nuclear DNA of the rat kidney cells increases as the postmortem interval lengthens and comet assay may provide important empirical evidence for determining the postmortem interval.

Deletion of dnd Gene Cluster in Salmonella enterica and Heterogenous Expression / 微生物学通报

Salmonella enterica serovar Cerro 87, which was isolated from a commercial egg-producing farm, has a phosphorothioated DNA backbone resulting DNA degradation(Dnd) during the pulsed field gel electrophoresis (PFGE) process. In this research, a gene deletion mutant XTG103 was engineered with the entire dnd gene cluster knocked out by double crossover using vector pKOV-kan, and lost Dnd phenotype corre- spondingly. We regulated the DNA phosphorothioation by heterogenous expression of dnd gene cluster with an isopropyl ?-D-1-thiogalactopyranoside (IPTG) inducible promoter PlacZ.

Determination of the Early Time of Death by Computerized Image Analysis of DNA Degradation: Which Is the Best Quantitative Indicator of DNA Degradation? / 华中科技大学学报（医学）（英德文版）

This study evaluated the correlation between DNA degradation of the splenic lymphocytes and the early time of death, examined the early time of death by computerized image analysis technique (CIAT) and identified the best parameter that quantitatively reflects the DNA degradation.The spleen tissues from 34 SD rats were collected, subjected to cell smearing every 2 h within the first 36 h after death, stained by Feulgen-Van's staining, three indices reflecting DNA content in splenic lymphocytes, including integral optical density (IOD), average optical density (AOD), average gray scale (AG) were measured by the image analysis. Our results showed that IOD and AOD decreased and AG increased over time within the first 36 h. A stepwise linear regression analysis showed that only AG was fitted. A correlation between the postmortem interval (PMI) and AG was identified and the corresponding regression equation was obtained. Our study suggests that CIAT is a useful and promising tool for the estimation of early PMI with good objectivity and reproducibility,and AG is a more effective and better quantitative indicator for the estimation of PMI within the first 36 h after death in rats.

Estimation of the postmortem interval by determining nuclear DNA degradation from bone marrows and brains in rats / 中国法医学杂志

Objective To detect nuclear DNA degradation of bone marrows and brains in rat cadavers at different temperatures,and develop a new parameter for estimating early postmortem interval(PMI).Methods The brain and bone marrow were taken out for every 4h,during 0~40h after death at 10℃ and 20℃,respectively.And the single cell gel electrophoresis(SCGE) was carried out to detect the nuclear DNA degradation.Linear regression analysis was used to assay the relationship of the comet parameter HeadDNA%,Tail Length(TL) and Olive TailMoment(TM) with PMI.Results Different decline degrees of comet HeadDNA% were found in both brain cells and bone marrow cells after death,the decline of HeadDNA% in brain cells at 20℃ was faster.Compared with degradation in marrow cells,the linear relation between degradation of brain cells and PMI was better.Conclusion with that of comet parameters TL and TM,the perfect linear relationship between HeadDNA% and PMI was also observed.Conclusion Brain tissues are more suitable for PMI estimation by detecting degradation of DNA with SCGE.The HeadDNA% is more valuable for PMI estimation than TL and TM.

Study on the relationship between the postmortem interval and the changes of DNA content in the rat's brain cells by the computerized image analysis / 中国法医学杂志

Estimation the postmortem interval(PMI)is an important subject in forensic medicine practice.Recent research has found that the DNA molecular would degrade immediately following death,and the quantity of DNA in nuclear would be decreasing along with the elapse of the time since death.Seven parameter of cell nuclear,including the area and integral optical density,were chosen and the changes of DNA content in the brain cells of 15 rats were determined at every one hour during 48 horus after death by the auto TV imange analyses system.The results showed that the degradation rate of DNA in nuclear has a certainty relationship with early PMI in rats and indicated that the determination of the quantity of DNA in nuclear is the major method to estimate the PMI.

Study on relationship between changes of DNA content in human spleen nuclei and the postmortem interval by image analysis / 中国法医学杂志

Objective To study changes of DNA content in human spleen nuclei and seek an experimental method for estimation of the postmortem interval(PMI)using computerized image-analysis technique(CIAT).Methods Smear sections from spleen sampled were collected in 36 cadavers with known the accurate PMI respectively every hour within the first 36 hours after death,which were then fixed with cold Carony fixation.The smeared sections were stained by Feulgen-van's staining method.3 indices for spleen nucleic DNA including integral optical density(IOD),average optical density(AOD)and average gray(AG)were measured using the CIAT.Results IOD and AOD in the spleen nuclei declined regularly,whereas AG increased with the extension of PMIs in 36 hours.Conclusion There are definite relationships between the PMI and gray parameters(IOD、AOD and AG)representing the DAN content of nucleic DNA in the spleen in 36 hours after death,which may be used for estimation of PMI.