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Objective:To evaluate the relationship between the Panton-Valentine leukocidin (pvl) strain and clinical characteristics, and to describe the molecular biological characteristics of invasive Staphylococcus aureus ( S. aureus) infected clinical isolates. Methods:The isolates of S. aureus caused by invasive infection were collected in Beijing Children's Hospital Affiliated to Capital Medical University from January 2016 to December 2019, and the clinical data of the corresponding children were collected retrospectively using electronic medical records. Multilocus sequence typing, spa typing and pvl gene were analyzed using the PCR. In addition, the minimum inhibitory concentrations (MIC) of antibiotics of all isolates were detected by the micro-broth dilution method, and the isolates were divided into the pvl+ and pvl- groups according to whether or not the S. aureus isolates carried pvl. The t test and the Mann-Whitney U test were used to compare the clinical symptoms between the pvl+ and pvl- groups. Chi-square test was used to compare the drug susceptibility between the two isolates. Results:A total of 127 cases of invasive S. aureus infection were collected during the study period. The white blood cell count, neutrophil count, and C-reaction protein level in the pvl+ group were significantly higher than those in the pvl- group ( P=0.001, P=0.001, P=0.005). The rate of pvl carrier was 44.9%. Among 57 pvl+ pathogenic strains, 64.9% (37/57) were MRSA. The multidrug resistance rate of pvl- isolates was higher than that of pvl+ isolates (70% vs. 49.12%, P=0.02). Conclusions:In invasive S. aureus infection, pvl+ strain is associated with elevated inflammatory markers in children. the positive rate of pvl is higher in clinical isolates, and the multidrug resistance rate of pvl- S. aureus is higher.
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Staphylococcus aureus ( S. aureus) is one of the most common human pathogens. It has been reported that Panton-Valentine Leukocidin (PVL) as a representative of virulence proteins is an important pathogenic factor for S. aureus infection. However, with the deepening of research, some researchers consider that pvl gene has little effect on the pathogenicity of S. aureus. This article aimed to review and summarize the recent studies on the features, molecular epidemiological characteristics, pathogenicity and controversy of pvl gene.
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Objective This study aims to evaluate the changes of Cdk5 expression at the time of 3 hours to 10 days after moderate brain injury by blunt force impact in a rat model,and to demonstrate its forensic significance.Methods To establish a rat model of blunt focal brain contusion,and to observe the changes of Cdk5 expression in brain tissue at different timepoints after brain injury by immunohistochemistry and Western blot.Results A low expression level of Cdk5 was observed in the brain tissue of both normal and sham control groups.The expression of Cdk5 increased after 3 and 6 hours,remarkably increased at 12 hours,and reached the maximal level at 24 hours after focal brain injury.The Cdk5 level gradually decreased 3 days,5 days,7 days,and 10 days and reached the normal level 7 and 10 days after the injury,with no statistical difference (P＞0.05) compared with the normal and sham control groups.Conclusion The expression of Cdk5 increased in the peripheral area of contusion tissue after blunt brain injury in rats,showing single peak change,and dropped to normal level with the time extension.The change of Cdk5 expression may provide a new reference index for the prediction of early brain contusion.
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T A R D N A-binding dom ain protein 43 (T D P-43) is a highly conserved and w idely expressed nuclear protein. N ow adays, the expression of T D P-43 can be found in m ost neurodegenerative diseases such as A lzheim er's disease, w hich m akes it becom e a neurodegenerative disease associated m arker pro-tein. From the current research status at hom eland and abroad, and around the relationship betw een the expression of T D P-43 and brain injury, this article em phatically probes into the specific expression and function of T D P-43 in acute and chronic brain injury based on the know ledge of its biological charac-teristics, w hich aim s to explore the feasibility for determ ining the cause of death and the injury and dis-ability situations by T D P-43 in forensic pathology.
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Objective To study the expression of p35 and p25 in rat after focal cerebral contusion and to provide experimental data for estimating brain injury time. Methods Fifty adult male SD rats were randomly divided into 0 h, 6 h, 12 h, 24 h, 3 d, 5 d, 7 d, 10 d after focal cerebral contusion, control and sham-operated groups (5 rats each group). The focal cerebral contusion rat model was established. The expression of p35 and p25 protein of the damage peripheral zone in brain were detected by HEstain-ing, immunohistochemistry and western blotting at different injury time. Results Alarge number of p35 protein and a small amount of p25 protein were expressed in control group and sham-operated group. After focal cerebral contusion, p35 presented unimodal change with time and p25 presented bimodal changes with time. Conclusion Expression of p35 and p25 showed different regularity with good time correlation, which could help to estimate the brain injury time.
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Brain injury is a kind of wound by violence on head, which is a mechanical distortion of skull, meninx, cerebral vascular and brain tissue due to outside force acting on head. Apolipoproteins E (ApoE ) is a major kind of apolipoprotein s, participating in the metabolismof lipid and regulating bal-ance of cholesterol. Some recent investigations showthat gene polymorphismof ApoE is associated with various kinds of diseases. Also its immunoreactivity is changed regularly with brain injury. In addition, ApoE has remarkable effect in neurological normal growth and reparative process after brain injury. This article reviews the biological characteristics and mechanismof ApoE in the repair of brain injury and application prospect in forensic medicine, which may be able to provide newideas for estimation of the brain injury time and related experimental research.
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M etallothionein (MT) is a kind of metal binding protein. As an im portant mem ber in metalloth-ionein fam ily, MT-Ⅰ/Ⅱ regulates metabolismand detoxication of brain metal ion and scavenges free radicals. It is capable of anti-inflam matory response and anti-oxidative stress so as to protect the brain tissue. During the repair process of brain injury, the latest study showed that MT-Ⅰ/Ⅱ could stim ulate brain anti-inflam matory factors, grow th factors, neurotrophic factors and the expression of the receptor, and prom ote the extension of axon of neuron,wich makes contribution to the regeneration of neuron and has im portant effect on the recovery of brain injury. Based on the findings, this article reviews the struc-ture, expression, distribution, adjustion, function, mechanism in the repair of brain injury of MT-Ⅰ/Ⅱand its application prospect in forensic medicine. It could provide anew approach for the design and manufacture of brain injury drugs as well as for age estimation of the brain injury.
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The present paper reports that the fenfluramine(FA), amphetamine(AP) and methamphetamine(MA) were extracted from the blood by the solid phase microextraction(SPME). The drugs were extracted for 15 min under the condition of 70℃ by a polydimethylsiloxane fiber. d5-methamphetamine(IS) was used as an internal standard. GC/MS was used for analysis with the injection method of derivatization on column. The ions at m/z 268(FA), m/z 240(AP), m/z 254(MA) and m/z 258(IS) in the selected ion minitoring chromatograms were selected for quantitation. Each compound was detectable at least 0 01～0 03 ?g/g. By determination of fenfluramine in poisoning blood, it is proved that this method would be demonstrated to be simple and accurate.
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Matrix metalloproteinase 3 is one of matrix metalloproteinase family members, which degrades a wide range of components of the extracellular matrix and participates in tissue morphogenesis, wound healing and inflammation. In addition, matrix metalloproteinase 3 is involved in pathogenesis and progress of a spectrum of diseases and malignant tumors, such as rheumatic arthritis, arteriosclerosis, breast cancer, and so on. Recent studies have demonstrated that matrix metalloproteinase 3 may be a novel signaling proteinase from apoptotic neuronal cells to microglia, which results in degeneration of neurons in Alzheimer's disease and Parkinson's disease by activating microglia. There is also an association between genetic polymorphisms of matrix metalloproteinase 3 at promoter region 5A/6A and susceptibility of myocardial infarction. Decrease in serum concentration of matrix metalloproteinase 3 after myocardial infarction may be a useful parameter for diagnosing sudden death due to myocardial infarction in forensic practice. Expression of matrix metalloproteinase 3 varies with different types of brain injuries, suggesting that it may contribute to synaptic plasticity during functional recovery. To elucidate the time-dependent expression of matrix metalloproteinase 3 may provide a new way for wound age determination in the brain.
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Objective To investigate the indicators for identifying diffuse axonal injury by blunt forces in forensic pathological practice. Methods The DAI model was produced by the fluid - percussion method in cats. The cerebral samples were stained by H. E. , Bodian, Kluver - Barrera stain and NF Immunohistochemistry. Changes of axons and myeline sheath were observed at different intervals after injury. Positive NF immunostained area in axons was measured, and the data was analyzed by SPSS 11.5 for windows. Results Changes of axons in subcortical white matter and brainstem were observed in the forms of swollen, waved and distorted axons in early stage after injury (1-2 hours). Markedly torn, vacuolated axons with formation of the retraction balls from 4 hours after injury were specifically demonstrated in NF immunohistochemistry (P