电流斑的环境扫描电镜X射线能谱分析

目的利用环境扫描电镜-X射线能谱仪(environmental scanning electron microscope and energydispersive X-ray microanalyser,ESEM-EDX)研究电流斑微观形态特征及元素构成,以期为电流斑及电击死的鉴定提供更准确、客观的依据。方法用ESEM-EDX检测5例电流斑的扫描电镜形态、金属颗粒的形态及其元素组成。结果电流斑及周围皮肤可见电穿孔、金属熔珠,熔珠主要由铁、铜、铝等常见金属元素和金、钛、钡等人体少见的金属元素构成。结论 ESEM-EDX检测可为电击死的鉴定提供客观的依据。     

不同高度钝力打击致大鼠皮肤与骨骼肌挫伤的对比

目的探讨不同高度钝力打击下,皮肤与骨骼肌挫伤后的修复过程差异。方法采用自主设计的自由落体打击装置,以打击高度为主要损伤程度考量因素,将自由落体从15、30、50 cm高度打击造成SD大鼠下肢三种不同程度的挫伤。采用组织形态学方法观察损伤后6 h、24 h、3 d、7 d、13 d皮肤及肌肉的修复过程。结果三个打击高度引起实验大鼠下肢挫伤,基本都可形成皮下组织和(或)肌肉内的出血,在伤后24h内修复的过程基本类似,但表现程度随打击高度增加而明显;15 cm挫伤组在3 d时出血区红细胞已基本融解消散,而30 cm挫伤组则延迟至7 d;伤后13 d时,15 cm和30 cm挫伤组表现基本类似,但50 cm挫伤组则仍处于增生旺盛期。结论随着打击高度的增加,皮肤及肌肉同时出血的比例明显增加,挫伤后组织修复的炎症反应、增生反应表现逐渐加重,修复的过程也出现相应的延长。综合法医学实践应用以及本研究结果,推荐以50 cm高度所致挫伤(2.58 J/cm~2)作为今后挫伤损伤时间研究的实验动物参考模型。     

Ochronosis Presenting as Methemoglobinemia

Ochronosis is the blue‐gray discoloration of collagen‐containing tissues due to homogentisic acid (HGA) deposition, secondary to endogenous alkaptonuria or exogenous enzyme inhibition. In renal disease, accumulation of HGA in serum can cause methemoglobinemia. A 60‐year‐old woman with renal disease and anemia presented with 3 days of weakness and months of gray skin discoloration. Her hemoglobin was 8.1g/dl with 24.5% methemoglobin. Despite treatment with methylene blue, exchange transfusion, and continuous renal replacement therapy, the patient died. Autopsy revealed gray discoloration and ochronotic pigment in the ribs and cartilage. Based on these findings, the patient was diagnosed with ochronosis, suggestive of alkaptonuria, complicated by methemoglobinemia. The differential diagnosis for blue‐gray skin discoloration includes argyria, methemoglobinemia, and ochronosis. This patient's clinical and autopsy findings suggested alkaptonuria complicated by methemoglobinemia due to progressive renal dysfunction. Development of methemoglobinemia in the setting of chronic skin discoloration and renal failure should prompt consideration of alkaptonuria.     

Discordance of Gross and Histologic Findings in Estimating the Range of Fire of Gunshot Wounds

Forensic pathologist use soot and/or stippling surrounding entrance gunshot wounds in categorizing range of fire. If absent, some pathologists suggest utilizing histology when the range is diagnostically critical. This study investigates the concordance of macroscopic and microscopic findings in estimating range of fire by evaluating gunshot entrance and exit wounds made through human tissue analogs at defined distances using two handgun calibers. Examination of over 150 entrance wounds verified the ease of visually detecting soot from a muzzle distance of contact to 1 foot (30.5 cm), and its absence at 9 feet (274.3 cm). Distinctly apparent was bullet wipe surrounding the entrance wounds regardless of muzzle distance. Although variations existed, dark material was histologically identified in many skin, soft tissue, and bone sections at all ranges with both calibers. These nonparallel results decrease the dependability of histology for range of fire estimation and reinforce using gross observation.     

小鼠皮肤创伤愈合过程中IL-10在不同表达部位的组化定量研究

目的探讨小鼠皮肤创伤愈合过程中IL-10在不同表达部位的变化与损伤时间的关系。方法应用免疫组织化学技术和形态计量法,对小鼠不同时程皮肤切创组织中IL-10不同表达部位(表皮细胞及表皮下组织的浸润细胞)的变化进行研究。结果皮肤切创前后表皮层均有阳性表达,切创后1～3h表皮细胞阳性表达水平迅速升高,24h时降至较低水平,伤后48h表达水平再次升高,96h后逐渐回复到正常水平;表皮以下阳性部位主要是浸润的单核/巨噬细胞,损伤6h后阳性细胞在真皮、皮下组织及创口肉芽组织内逐渐增多,于伤后72h达最大值(51.41±3.12)%,96～168h阳性细胞数逐渐减少(29.38±2.64)%～(5.56±4.74)%。结论皮肤创伤修复过程中IL-10在不同表达部位的变化特点与皮肤损伤时间相关,检测其表达变化可望用于损伤时间推断。     

皮肤切创愈合中caspase-3表达的免疫组化研究

目的探讨皮肤切创损伤愈合过程中,caspase-3在损伤区内的表达以及不同损伤时间caspase-3的变化规律。方法应用免疫组织化学技术对33例不同损伤时间小鼠皮肤切创组织中caspase-3的表达进行研究。同时以3例非切创小鼠皮肤组织做对照。结果伤后6h的损伤皮肤组织中可见少量中性粒细胞表达caspase-3,伤后12～24h,大部分浸润的中性粒细胞及部分单核细胞为caspase-3阳性。随伤后时间延长,caspase-3阳性细胞以单核细胞及成纤维细胞为主。伤后0～3h,caspase-3阳性细胞比率较低,为(4.53±6.53)%,12h后逐渐增加,伤后3d达高峰,为(62.66±4.84)%,其后逐渐下降。结论小鼠皮肤损伤愈合过程中,caspase-3可能在诱导损伤区内中性粒细胞、单核巨噬细胞及成纤维细胞发生凋亡过程中发挥重要作用,同时,caspase-3的规律性表达可用于损伤时间的推断。     

皮肤切创组织IL—2、TNF—α时间相关性表达的ELISA分析

目的了解细胞因子在创伤及修复过程中的表达的含量变化与损伤时间的关系。方法用免疫酶联吸附方法(ELISA)检测不同损伤时间(生前伤0.5～168h)实验动物皮肤切创组织中IL-2和TNF-a的表达水平。结果IL-2、TNF-a在造创后0.5h即升高,并分别在造创后3h和1h到达峰值,在造创后48h均有反弹,在72h和168h持续升高。结论上述细胞因子在创口修复中的蛋白表达水平呈时间相关性特点。     

Fatal Firearm Injuries in Tennessee: A Comparison Study of Tennessee's Two Most Populous Counties 2009–2012

Firearm injuries are a leading cause of violent death in Tennessee. This study was designed to compare the demographic and epidemiologic features of fatal firearm injuries in Shelby County and Davidson County, Tennessee between 2009 and 2012. We identified 1081 gunshot fatalities for the study period in these two counties. Shelby County had a higher overall, age‐adjusted gunshot mortality rate, a higher male age‐adjusted gunshot mortality rate, and a higher age‐adjusted gunshot homicide rate than Davidson. Age groups 25–34 years and 35–44 years had higher crude mortality rates for gunshot deaths in Shelby County than Davidson County. Both counties had higher age‐adjusted gunshot mortality rates for black males than white males, higher homicide rate for black race than white, and higher suicide rate for white race than black. Homicide was the most common manner of death, and handguns were the most common type of firearm used in both counties.     

Comparative Evaluation of Potentially Radiolucent Projectile Components by Radiographs and Computed Tomography

Projectile components that are traditionally radiolucent can be of considerable importance in determination of weapon type and caliber, but they are often missed on evaluation of postmortem radiographs. We hypothesized that these components would be significantly better visualized by evaluation of computed tomography (CT) scans compared to the practice standard of radiography alone. In this project, potentially radiolucent projectile components were both pulled apart and fired, and the radiolucent components were recovered. These components were embedded in blocks of ballistics gelatin and were imaged using both radiography and CT. The scans were evaluated by three blinded, board‐certified radiologists for the presence/absence of projectile components and true‐negative regions in each block. If a radiologist indicated visualization of a projectile component, they were further requested to describe their observation. It was found that traditionally radiolucent projectile components are not significantly more often identified on CT scans than radiography (p < 0.05).     

Time‐dependent Expression of MMP‐2 and TIMP‐2 after Rats Skeletal Muscle Contusion and Their Application to Determine Wound Age

The ability to determine vitality and estimate the survival period after a wound is critical in routine forensic practice. The mRNA levels of MMP‐2 and TIMP‐2 were examined using quantitative real‐time RT‐PCR to determine the age of a wound. Furthermore, the colocalization of them with Macrophage Marker, respectively, was detected by double immunofluorescence, and a standardized rat model of skeletal muscle contusion was established. In the antemortem contused groups, a large number of macrophages showed positive staining for MMP‐2 and TIMP‐2, and the expression of MMP‐2 and TIMP‐2 mRNA increased sharply at 3 days postinjury, with relative quantities of 5.75 and 2.98. No samples in the other groups showed relative quantities of >5.75 and 2.98; therefore, relative quantities exceeding 5.75 and 2.98 were strongly indicated 3 days after contusion. In addition, there was a significant decrease in the relative quantity in the postmortem contused groups, indicating that they were useful for diagnosing vitality.