Research Progress on the Determination of Electrical Conductivity in Forensic Science / 法医学杂志

Electrical conductivity （EC） is an important physical and chemical index in electrochemical analysis. In recent years, with the penetration and reference of transformation medicine and interdisciplinary theory and technology in the forensic field, new applications of EC in the field of forensic science have been developed. This paper reviews three aspects of the application of EC, the determination of biological tissue freshness, postmortem interval estimation and the application in forensic taphonomy, in order to provide reference for relevant scientific research and related practices.

Relationship between Electrical Conductivity and Chemical Content of Rat Skeletal Muscle Impregnating Solution and Postmortem Interval / 法医学杂志

Objective To study the mechanism of change of the electrical conductivity （EC） of rat skeletal muscle impregnating solution that occurs with the change of postmortem interval （PMI）. Methods Healthy Sprague-Dawley rats were killed and kept at about 25 ℃. Skeletal muscles were extracted at different PMI--immediate （0 d）, 1 d, 2 d, 3 d, 4 d, 5 d, 6 d, and 7 d, then mixed with deionized water to make impregnating solution with a mass concentration of 0.1 g/mL. The solution's EC and nine common chemicals in it, such as potassium ion, calcium ion, and chloride ion, were determined. Results EC increased gradually with the extending of PMI （P=0.024） during the 7 days after the rats' death. The content of uric acid （P=0.032）, urea nitrogen （P=0.013） and phosphorus （P=0.022） also increased during the extension. However, the content of magnesium ions decreased with extending of PMI （P=0.047）. The correlation between potassium ion, sodium ion, chlorine ion, calcium ion, creatinine and PMI were weak （P>0.05）. Conclusion The molecular basis of skeletal muscle EC change in rats after their death is the changes of uric acid, urea nitrogen, inorganic phosphorus and other chemical components. Furthermore, combine use of various indicators can improve the accuracy of the EC method to infer PMI.

Relationship between Electrical Conductivity and Related Biochemical Indicators of Rat Cerebrum Tissues and Postmortem Interval / 法医学杂志

Objective To explore the relationship between the electrical conductivity （EC） and biochemical indicators of rat cerebrum tissues and postmortem intervals （PMIs） and discuss the mechanism of applying EC to infer PMI. Methods Forty healthy Sprague-Dawley rats were sacrificed and stored in an environment of about 25 ℃. The whole cerebrum tissues of rats were removed respectively at different PMIs of 0, 1, 2, 3, 4, 5, 6, and 7 d, and then made into homogenized impregnation solution. The EC and related biochemical indicators （potassium, sodium, chloride, calcium, inorganic phosphorus, magnesium, uric acid, urea nitrogen and creatinine） in cerebrum tissue impregnation solution were determined, and the relationships among EC in impregnation solution, related biochemical indicators and PMI were analyzed. Results The EC in cerebrum tissues increased gradually with the extension of PMI, and the content of uric acid, urea nitrogen and inorganic phosphorus in its impregnation solution also increased gradually with the extension of PMI. The correlation of EC, uric acid, urea nitrogen, and inorganic phosphorus with PMI was relatively good （R2 was 0.95-0.99）, and there was a linear correlation between the content change of uric acid, urea nitrogen, inorganic phosphorus and EC （R2 was 0.97-0.99）. The changes of the other 6 kinds of biochemical indicators with the extension of PMI within 7 d after the rats' death were non-significant （P>0.05）. Conclusion The correlation between EC in cerebrum tissues, uric acid, urea nitrogen, inorganic phosphorus and PMI were relatively good, and combining various indicators can also improve the accuracy of PMI estimation.

Analysis of 28S rRNA and COⅠ Gene Sequence of Nine Necrophagous Calliphorid Flies from Luoyang / 法医学杂志

Objective To assess the feasibility of using 28S ribosomal RNA （28S rRNA） and mitochondrial cytochrome c oxidase subunit Ⅰ （COⅠ） gene sequences of nine necrophagous Calliphorid flies for the identification of common necrophagous Calliphorid flies, and to provide technical support for postmortem interval （PMI） estimation. Methods Twenty-three Calliphorid flies were collected and identified morphologically, and DNA were extracted from legs. The gene fragments of 28S rRNA and COⅠ were amplified and sequenced, then the sequence alignment was performed with BLAST. The composition of obtained sequences was analyzed and evolutionary divergence rate between species and intraspecies were established. The phylogeny tree was constructed with neighbor-joining method. Results The 23 necrophagous Calliphorid flies were identified to 9 species of 5 genera. The 715 bp from 28S rRNA and 637 bp from COⅠ gene were obtained and the online BLAST result showed more than 99% of similarity. The phylogeny tree showed that the necrophagous flies could cluster well into 9 groups, which was consistent with morphological identification results. The intraspecific difference in 28S rRNA was 0 and the interspecific difference was 0.001-0.033. The intraspecific difference in COⅠ was 0-0.008 and the interspecific difference was 0.006-0.101. Conclusion Combined use of 28S rRNA and COⅠ gene sequence fragments can effectively identify the nine Calliphorid flies in this study. However, for closely related blowfly species, more genetic markers should be explored and used in combination in future.

Relationship between Early Postmortem Interval and Electrical Conductivity of Rat Liver, Spleen and Kidney after Death in Rats / 法医学杂志

OBJECTIVES@#To determine the electrical conductivity （EC） of the liver, spleen and kidney of rats at different postmortem intervals （PMIs） within 24 hours for investigating the relationship between EC of different organs and early PMI.@*METHODS@#Totally 45 SD rats were sacrificed by cervical dislocation and kept at a constant temperature of 25 ℃. Tissues were taken from the liver, spleen, and kidney of rats at 0, 3, 6, 9, 12, 15, 18, 21 and 24 h. Impregnating solution with a mass concentration 0.1 g/mL was prepared using deionized water. The EC value of impregnating solution with different organs was separately determined. The regression equations of EC and PMI for different organs were established, respectively. The relationship between EC of different organs and early PMI was analysed in deceased rats.@*RESULTS@#The relationship between PMI and EC of the liver and spleen was well fitted with the linear equation. The liver showed the best fitting degree followed by the spleen, while the EC of the kidney showed no significant changes within 24 h. There was a good linear relationship between early PMI and the EC of the liver and spleen.@*CONCLUSIONS@#A good linear relationship between early PMI and the EC of the liver and spleen can be found in rats after death, which can be used for the early PMI estimation.

The gluteal perforator-based flap for repair of refractory wounds on different sites of buttocks / 中华整形外科杂志

<p><b>OBJECTIVE</b>To discuss the application of perforator-based flap for repair of refractory sacral, ischial and trochanter wounds.</p><p><b>METHODS</b>Vacuum sealing drainage (VSD) were applied for all the wounds for 6 - 21 days and cutaneous perforator was detected by Doppler before operation. According to the location of the perforator arteries, different types of perforator-based flaps were used to cover the wounds on the buttocks.</p><p><b>RESULTS</b>Since 2005, 18 wounds in 14 patients were treated, including 11 sacral, 5 ischial and 2 trochanter defects. All flaps survived with primary healing.All the patients were followed up for 2 to 24 months with no ulcer relapse. The colour and texture of the flaps were excellent with satisfactory cosmetic results.</p><p><b>CONCLUSION</b>The gluteal perforator-based flaps have reliable blood supply with less morbidity in donor sites. It is an optimal method in repairing refractory wounds of the gluteal region.</p>

Clinical efficacy of artery perforator-based flap in the repair of gluteal-sacral pressure sores / 中华烧伤杂志

<p><b>OBJECTIVE</b>To investigate the clinical efficacy of artery perforator-based flap in the repair of gluteal-sacral pressure sores.</p><p><b>METHODS</b>Gluteal artery perforator-based island flap and perforator-based flap were designed to repair the gluteal-sacral pressure sores of 26 patients according to the location and size of the wounds. The area of the biggest flap was 20 cm x 15 cm, the diameter of perforating vessel was above 1. 1 mm, with the length of free pedicle ranging from 2.0 - 3. 5 cm.</p><p><b>RESULTS</b>All the flaps healed soon after operation, with no flap necrosis and postoperative complications, such as flap necrosis, wound infection and or formation. The color and texture of the flaps were good and the configuration was satisfactory. There was no recurrence of local bedsore in the follow-up period from 6 to 24 months.</p><p><b>CONCLUSION</b>The artery perforator-based flaps have the advantages of delicate texture, easy dissection, reliable blood flow, preservation of the gluteus maximus muscle and no need of skin grafting for the donor defects in most cases. It is an optimal method in surgical treatment of gluteal-sacral pressure sores.</p>

Long-term in vitro culture of the fibroblasts from the deep partial thickness burn wound in burn patients / 中华烧伤杂志

<p><b>OBJECTIVE</b>To establish a long-term in vitro culture of the fibroblasts obtained from burn wounds.</p><p><b>METHODS</b>Skin samples were harvested from normal volunteers and the deep partial thickness burn wound in burn patients on the 5th, 10th, 21st, 28th and 35th postburn days (PBDs). The non-dermal tissue was removed from the samples and primed by chlorhexidine solution in concentration of 2.5 g/L. The skin sample was then digested by trypsin-EDTA in concentration of 1.25 g/L and was centrifuged before the cells were harvested and cultured. When the cells grew nearly to form sheet, multiple passage culture, freezing storage and revivification were carried out with routine methods. The cell morphology was continuously observed during the culture. And the cell doubling time was calculated.</p><p><b>RESULTS</b>The wound-origin fibroblasts exhibited higher purity and better activity. The cellular growth features and gross morphology kept stable during primary and secondary culture, and during freezing storage and after revivification. The cells kept their activity above 80% of their original after many times of revivification.</p><p><b>CONCLUSION</b>The establishment of the in vitro culture of fibroblasts from burn wounds might be useful in the exploration of the pathogenesis and therapeutic measures of scars.</p>