Connexin 43, angiotensin II, endothelin 1, and type III collagen alterations in heart of rats having undergone fatal electrocution

Advances in forensic diagnosis of electric shock death in the absence of typical electrical marks

Electrical injury is a relatively uncommon but potentially devastating form of multi-system injury with high morbidity and mortality. In common electric injury cases, it is usually difficult to find characteristic changes of electric injury in major organs by using routine histopathological test methods unless there are landmark traces of electric injury, known as electric marks. How to determine electric shock death, especially in the absence of typical electrical marks on the body surface in some cases (which account for about two-thirds of electric injury cases), remains a challenging problem in forensic practice. Our summary shows that many current related studies have focused their efforts to find characteristic histopathological changes in major organs of the body caused by electric injury. Based on the results obtained through comparison of the literature, we find that it may be more urgent and important to find the optimal autopsy or sampling sites in cases with no typical electric marks, knowing that these sites may often reflect the most significant histopathological changes of electric injury, for instance anatomy and sampling of the anterior wrist and the medial malleolus in cases involving the hand-to-foot electric circuit pathway. In this article, we make a summary of advances in identification methods of electric injury, hoping that it could provide some new insights for further research in this field.

A Pilot Study on the Diagnosis of Fatal Electrocution by the Detection of Myocardial Microhemorrhages

In electrocutions, death may be caused by alterations in the heart conduction system provoking ventricular fibrillation. This study aims to identify histological cardiac markers of high- and low-voltage electrocution. Two groups of decedents were evaluated: group A included 14 fatalities caused by high- or low-voltage electrocution and group B (control) included 14 fatalities due to other traumatic or disease causes. Myocardial sampling with microscopic examination was performed on all the hearts using the hematoxylin and eosin and Masson's trichrome stains to investigate morphological characteristics that could indicate the damage caused by high- and low-voltage electrocutions. Interstitial myocardial hemorrhagic infiltration was the only differentiating finding, which was shown only in high-voltage electrocution. This pathological finding has not been previously reported, and it may be specific to high-voltage electrocution deaths. Further studies are warranted.

Phosphorylation of Cx43 residue Y313 by Src contributes to blocking the interaction with Drebrin and disassembling gap junctions

Phosphorylation regulates connexin43 (Cx43) function from assembly/disassembly to coupling at the plaque. Src is a tyrosine kinase known to both phosphorylate Cx43 (residues Y247 and Y265) and affect gap junction intercellular communication. However, the Cx43 carboxyl-terminal (CT) domain contains additional tyrosine residues and proteomic discovery mass spectrometry data identified Y313 as a potential phosphorylation target. Based upon the study of Lin et al. (2001) J. Cell Biol., which still observed tyrosine phosphorylation by Src when using a Cx43 Y247/Y265F mutant, we addressed the possibility of Y313 phosphorylation (pY313) by Src. In vitro Src phosphorylation of purified Cx43CT followed by mass spectroscopy revealed that Src also phosphorylates Y313. This observation was confirmed by repeating the in vitro phosphorylation using different combinations of Cx43CT Y → F mutants and a general anti-pTyr antibody. Next, a phospho-specific antibody was generated to help characterize the importance of pY313. We established an in cyto experimental system by stably expressing Cx43 WT and mutants (Y247F, Y265F, Y313F, Y247/265F, Y247/313F, Y265/313F, or Y247/265/313F) in Cx43-deficient HeLa cells. Cx43 WT and mutants, in the absence of v-Src, localized to the plasma membrane and formed gap junctions. When v-Src was over-expressed, Cx43 WT localized intracellularly, while all of the single and double mutants remained able to form plaques and transfer dye, albeit variable in number and amount, respectively. Complete Src-resistance was only achieved with the Cx43 Y247/265/313F mutant. Furthermore, Cx43 Y265F inhibited the ability of v-Src to phosphorylate Y247 and Y313 as well as phosphorylation at both Y265 and Y313 was necessary to inhibit the Cx43 interaction with Drebrin. Finally, we observed in diseased cardiac tissue, in which Src is active, an increase in intercalated disc and intracellular localized Cx43 pY313.

Forensic tools for the diagnosis of electrocution death: Case study and literature review

Diagnosis of death by electrocution may be difficult when electric marking is not visible or unclear. Accordingly, the body of a man who appeared to have died from accidental electrocution was carefully forensically analysed. Macroscopic and microscopic analysis of the current mark was carried out using a variable-pressure scanning electron microscope equipped with energy dispersive X-ray microanalyser to highlight skin metallisation, indicating the presence of iron and zinc. The histological findings of electrocution myocardial damage were supported by the results of biochemical analysis which demonstrated the creatine kinase-MB and cardiac troponin I elevation. The effects of electric current flow were also highlighted by perforations of endothelial surface of a pulmonary artery using scanning electron microscope, and all the results were analysed by the main tools suggested in the literature.

Regulation of Connexin43 Function and Expression by Tyrosine Kinase 2

Connexin43 (Cx43) assembly and degradation, the regulation of electrical and metabolic coupling, as well as modulating the interaction with other proteins, involve phosphorylation. Here, we identified and characterized the biological significance of a novel tyrosine kinase that phosphorylates Cx43, tyrosine kinase 2 (Tyk2). Activation of Tyk2 led to a decrease in Cx43 gap junction communication by increasing the turnover rate of Cx43 from the plasma membrane. Tyk2 directly phosphorylated Cx43 residues Tyr-247 and Tyr-265, leading to indirect phosphorylation on residues Ser-279/Ser-282 (MAPK) and Ser-368 (PKC). Although this phosphorylation pattern is similar to what has been observed following Src activation, the response caused by Tyk2 occurred when Src was inactive in NRK cells. Knockdown of Tyk2 at the permissive temperature (active v-Src) in LA-25 cells decreased Cx43 phosphorylation, indicating that although activation of Tyk2 and v-Src leads to phosphorylation of the same Cx43CT residues, they are not identical in level at each site. Additionally, angiotensin II activation of Tyk2 increased the intracellular protein level of Cx43 via STAT3. These findings indicate that, like Src, Tyk2 can also inhibit gap junction communication by phosphorylating Cx43.

Electrical Injuries in Animals: Causes, Pathogenesis, and Morphological Findings

Electrical injuries in animals occur most often accidentally. They comprise contact to various forms of currents, including alternating, rotary, or direct currents. Depending on various parameters of the current (including the type of circuit, voltage, current and duration of exposure) and conditions of the animal (such as wet or dry hair coat and pathway of current through the body), lesions may be absent or may include early or localized development of rigor mortis, signs of acute circulatory failure, or severe thermoelectrical burns. Such burns may present as external current marks, singed hair or feathers, metallization of the skin, or occasionally internal electroporation injury resulting in muscle necrosis, hemolysis, vascular damage with thrombosis, injury to brain and spinal cord, or skeletal fractures. Furthermore, lightning strikes occur regularly in grazing animals, which have greater risk of death from step potentials (ground current) in addition to direct strike and contact injury. Such cases may have no lesions, external signs of linear or punctate burns, keraunographic markings, or exit burns on the soles of the hooves or the coronary bands. Besides detailed information about the circumstances at the location where the animal was found, electrical injuries in animals require a thorough morphological workup, including additional investigations in conjunction with certain knowledge about the possible lesion spectrum.

The effect of elapsed time on cardiac troponin-T (cTnT) degradation and its dependency on the cause of death

PURPOSE

The aim of the present study is to evaluate the effect of elapsed time on cardiac troponin-T degradation and its dependency on the cause of death.

METHODS

The cases included in this study were divided into six groups depending upon the cause of death without any prior history of disease that died in the hospital and their exact time of death was known. The analysis involves extraction of the protein, separation by denaturing gel electrophoresis and visualization by Western blot.

RESULTS

Western blot data shows the rate of degradation of cTnT into lower molecular weight fragments with respect to time. In cases of control group the greatest amount of protein breakdown was observed within the first 64 h while in MI cases within first 6 h, the original band of cTnT (42 kDa) decreased markedly into seven major fragments, with 25 kDa & 20 kDa fragments being the most prominent. In burn group, at 41.40 h blot shows maximum fragmentation. In electrocution group the greatest amount of protein breakdown was observed within the first 50 Hrs. Within asphyxia cases, the original band of cTnT (42 kDa) decreased markedly into many major and minor fragments which continues up to 210 Hrs while the original band of cTnT (42 kDa) in poisoning cases decreased markedly into many major & minor fragments up to 140 h but after it blot shows only intact protein of very less intensity with few minor fragments.

CONCLUSION

It can be observed that in case of death due to MI, the intact cTnI fragmented at a much faster rate than in burn, electrocution, control, poisoning and asphyxia group. Thus, the rate of fragmentation of intact cTnT into lower molecular weight fragments depends upon the cause of death.

Animal experimentation in forensic sciences: How far have we come?

In the third millennium where ethical, ethological and cultural evolution seem to be leading more and more towards an inter-species society, the issue of animal experimentation is a moral dilemma. Speaking from a self-interested human perspective, avoiding all animal testing where human disease and therapy are concerned may be very difficult or even impossible; such testing may not be so easily justifiable when suffering-or killing-of non human animals is inflicted for forensic research. In order to verify how forensic scientists are evolving in this ethical issue, we undertook a systematic review of the current literature. We investigated the frequency of animal experimentation in forensic studies in the past 15 years and trends in publication in the main forensic science journals. Types of species, lesions inflicted, manner of sedation or anesthesia and euthanasia were examined in a total of 404 articles reviewed, among which 279 (69.1%) concerned studies involving animals sacrificed exclusively for the sake of the experiment. Killing still frequently includes painful methods such as blunt trauma, electrocution, mechanical asphyxia, hypothermia, and even exsanguination; of all these animals, apparently only 60.8% were anesthetized. The most recent call for a severe reduction if not a total halt to the use of animals in forensic sciences was made by Bernard Knight in 1992. In fact the principle of reduction and replacement, frequently respected in clinical research, must be considered the basis for forensic science research needing animals.

Electrocution-related mortality: a review of 71 deaths by low-voltage electrical current in Guangdong, China, 2001-2010

The aim of this study was to investigate the epidemiological characteristics of low-voltage electrocution deaths in Guangdong, China. Three thousand three hundred seventy autopsy reports from the Department of Forensic Pathology, Zhongshan School of Medicine, Sun Yat-Sen University, over a period of 10 years (2001-2010) were reviewed, of which 71 low-voltage electrocution cases were identified. The descriptive statistical analyses were carried out with the application of SPSS 19.0 software. Electrocution accounted for 2.11% of all autopsied cases. The age range was 3 to 57 years with a mean age of 31.77 ± 11.0 years. The average age of male victims was 33.08 ± 10.77 years, and that of female victims was 22.63 ± 11.06 years. The majority of the victims (87.33%) were male. Among the circumstances leading to electrocution, most of them occurred in factory and in the street. Considering the contact details, deaths were caused most frequently by touching electrical wires (n = 27, 38.02%), followed by touching charged machine (n = 20, 28.17%). There were no suicide and homicide cases. Of all electrocution cases, 50.70% occurred during the summer period from June through August. The upper extremity was the most frequently involved contact site (59.72%). No electrical burn marks were present in 14 cases (19.72%). Our results indicated that most deaths from electrocution occur more often in factories, in summer seasons, and to young male workers, which can help in the development of a differentiated strategy for the prevention of electrocution, while taking into consideration sex, age, occupation, and season of the year.

Changes in FABP1 and gastrin receptor expression in the testes of rats that have undergone electrical injury

Testicular trauma may occur due to accidental electrical injury. The aim of this study was to investigate alterations in the levels of fatty acid-binding protein 1 (FABP1) and gastrin receptor (gastrin R) in the testes following electrical injury. Sprague-Dawley rats were divided into control, fatal electrocution (220 V, 50 Hz, 60 sec) and electrical injury (220 V, 50 Hz, 60 sec) groups (n=8 per group). The animals in the fatal electrocution and electrical injury groups were deeply anesthetized with sodium pentobarbital prior to each treatment, in which the current was delivered via an anode connected to the left foreleg and a cathode to the right hindleg. The rats that survived were subsequently sacrificed by cervical dislocation. Control animals received cervical dislocation alone. Immunohistochemical analysis was performed to evaluate the protein expression of FABP1 and gastrin R in the testes. Sections were evaluated by digital image analysis. The expression levels of FABP1 and gastrin R were significantly increased following electrical injury, supported by an increase in the integrated optical density (IOD) when compared with that in the control group (P<0.05). However, no significant difference was found in FABP1 and gastrin R expression levels between the fatal electrocution and control groups. In summary, the protein expression levels of FABP1 and gastrin R were found to be significantly altered by electrical injury, suggesting that these two proteins may be important in underlying mechanisms of testicular injury during electrical injury. The findings indicate that such alterations would be reflected in abnormal testicular function.

Dysregulation of Mfn2 and Drp-1 proteins in heart failure

Therapeutic approaches for cardiac regenerative mechanisms have been explored over the past decade to target various cardiovascular diseases (CVD). Structural and functional aberrations of mitochondria have been observed in CVD. The significance of mitochondrial maturation and function in cardiomyocytes is distinguished by their attribution to embryonic stem cell differentiation into adult cardiomyocytes. An abnormal fission process has been implicated in heart failure, and treatment with mitochondrial division inhibitor 1 (Mdivi-1), a specific inhibitor of dynamin related protein-1 (Drp-1), has been shown to improve cardiac function. We recently observed that the ratio of mitofusin 2 (Mfn2; a fusion protein) and Drp-1 (a fission protein) was decreased during heart failure, suggesting increased mitophagy. Treatment with Mdivi-1 improved cardiac function by normalizing this ratio. Aberrant mitophagy and enhanced oxidative stress in the mitochondria contribute to abnormal activation of MMP-9, leading to degradation of the important gap junction protein connexin-43 (Cx-43) in the ventricular myocardium. Reduced Cx-43 levels were associated with increased fibrosis and ventricular dysfunction in heart failure. Treatment with Mdivi-1 restored MMP-9 and Cx-43 expression towards normal. In this review, we discuss mitochondrial dynamics, its relation to MMP-9 and Cx-43, and the therapeutic role of fission inhibition in heart failure.

Aliskiren-attenuated myocardium apoptosis via regulation of autophagy and connexin-43 in aged spontaneously hypertensive rats

There are controversies about the mechanism of myocardium apoptosis in hypertensive heart disease. The aim of this study was to investigate the relationship among autophagy, Cx43 and apoptosis in aged spontaneously hypertensive rats (SHRs) and establish whether Aliskiren is effective or not for the treatment of myocardium apoptosis. Twenty-one SHRs aged 52 weeks were randomly divided into three groups, the first two receiving Aliskiren at a dose of 10 and 25 mg/kg/day respectively; the third, placebo for comparison with seven Wistar-Kyoto (WKY) as controls. After a 2-month treatment, systolic blood pressure (SBP), heart to bw ratios (HW/BW%) and angiotensin II (AngII) concentration were significantly enhanced in SHRs respectively. Apoptotic cardiomyocytes detected with TUNEL and immunofluorescent labelling for active caspase-3 increased nearly fourfolds in SHRs, with a decline in the expression of survivin and AKT activation, and an increase in caspase-3 activation and the ratio of Bax/Bcl-2. Myocardium autophagy, detected with immunofluorescent labelling for LC3-II, increased nearly threefolds in SHRs, with the up-regulation of Atg5, Atg16L1, Beclin-1 and LC3-II. The expression of Cx43 plaque was found to be down-regulated in SHRs. Aliskiren significantly reduced SBP, HW/BW%, AngII concentration and the expression of AT(1)R. Thus, Aliskiren protects myocardium against apoptosis by decreasing autophagy, up-regulating Cx43. These effects showed a dose-dependent tendency, but no significance. In conclusion, the myocardium apoptosis developed during the hypertensive end-stage of SHRs could be ameliorated by Aliskiren via the regulation of myocardium autophagy and maladaptive remodelling of Cx43.