|Year : 2015 | Volume
| Issue : 4 | Page : 941-947
Effects of low-voltage electrocution on hearts of male albino rats: a histopathological and immunohistochemical study
Samy Moustafa Badawy, Bothina Labib Mahmoud, Samy Abd El Hady Hamad, Ahamed Kamal El Fiky, Situhom El Sayed El Agmy MBBCh, MSc
Department of Forensic Medicine and Clinical Toxicology, Faculty of Medicine, Menoufia University, Menoufia, Egypt
|Date of Submission||30-Sep-2013|
|Date of Acceptance||12-Jan-2014|
|Date of Web Publication||12-Jan-2016|
Situhom El Sayed El Agmy
Department of Forensic Medicine and Clinical Toxicology, Faculty of Medicine, Menoufia University, Toukh Dalaka, Tala, Menoufia, 32613
Source of Support: None, Conflict of Interest: None
The aim of the present study was to detect histopathological and immunohistochemical changes in the heart of albino rats after low-voltage electrocution in an attempt to confirm the diagnosis of electrocution as a proximate cause of death.
Electrical injuries are often dramatic accidents and are potentially fatal. Many victims of electric shock die before help arrives and survivors may suffer severe injuries. Forensic pathologists have made several attempts to find an effective means to establish the cause of death by electrocution. Familiarity with both the incidence of the problem and the mechanism of injuries may lead to a more skillful means of diagnosing this type of death.
Materials and methods
Twenty-six adult male albino rats were divided randomly into two main groups: control group (I) and experimental group (II). The control group (I) included 10 rats that were killed by cervical dislocation without any application of electrical current. The experimental group (II) included 16 rats that were electrocuted until death by a 220 V alternating current with the points of electrical contact placed on the skin of the left forelimb and the skin of the right hind limb. Sections from the hearts of both groups were fixed in formalin and routinely processed. Caspase-3 expression was evaluated in both groups by immunohistochemistry.
Areas of interstitial hemorrhage, necrotic, and fragmented cardiomyocytes, square or rounded nuclei, myocardial waviness, and contraction bands were the prominent histopathological findings in the heart specimens of the rats of the electrocuted group (II) in comparison with the control group (I). Also, they showed a positive immune reaction for caspase-3 when compared with the control group.
This study concluded that the histopathological changes and immunohistochemical findings, besides the circumstantial evidence and external marks that may be found at autopsy, may provide a basis for the diagnosis of deaths caused by electrocution in suspected cases associated with limited external findings. Thus, it is advisable to use these techniques routinely in examinations and for the diagnosis of all deaths suspected to have been caused by electrocution.
Keywords: electrocution, forensic, heart, pathologists, proximate, voltage
|How to cite this article:|
Badawy SM, Mahmoud BL, El Hady Hamad SA, El Fiky AK, El Agmy SE. Effects of low-voltage electrocution on hearts of male albino rats: a histopathological and immunohistochemical study. Menoufia Med J 2015;28:941-7
|How to cite this URL:|
Badawy SM, Mahmoud BL, El Hady Hamad SA, El Fiky AK, El Agmy SE. Effects of low-voltage electrocution on hearts of male albino rats: a histopathological and immunohistochemical study. Menoufia Med J [serial online] 2015 [cited 2020 Mar 30];28:941-7. Available from: http://www.mmj.eg.net/text.asp?2015/28/4/941/173679
| Introduction|| |
Electricity is a real danger in the modern world due to several reasons; its invisible nature which makes it difficult to recognize, its great spread and our familiarity with it  . Also, the application of electrically powered machinery has led to an increase in the number of electrical injuries and deaths  .
Electrocution is death caused by electric shock, either accidental or deliberate. The word is derived from 'electro' and 'execution', but it is also used for accidental death. The term 'electrocution,' coined around the time of the first use of the electric chair in 1890, originally referred only to electrical execution (from which it is a portmanteau word), and not to accidental or suicidal electrical deaths. However, as no English word was available for nonjudicial deaths because of electric shock, the word 'electrocution' was eventually used as a description of all circumstances of electrical death caused by the new commercial electricity. The first recorded accidental electrocution (besides lightning strikes) occurred in 1879 when a stage carpenter in Lyon, France, touched 250 V wires  .
Electrical exposure is a major cause of injury and death in both the industrial and the home environment. The human body conducts electricity. If the body makes contact with an electrically 'energized' surface while simultaneously making contact with another surface at a different potential (or 'ground'), then an electric current will flow through the body, entering the body at one contact point, traversing the body, and exiting at the other contact point  .
Deaths because of the passage of electric current through the body are most often accidental, although suicides and homicides may occasionally occur. Electric shocks have also been used as a method of torture as the voltage received and amperage can be controlled with precision and used to cause pain while avoiding obvious evidence of this on the victim's body  .
Classifications of electrical injuries generally focus on the power source (lightning or electrical), voltage (high or low voltage), and type of current (alternating or direct), each of which is associated with certain injury patterns , .
Clinical manifestations range from transient unpleasant sensations without apparent injury to massive tissue damage. Some electrocutions are instantly fatal. Familiarity with the mechanisms of injury and the principles of therapy can improve patient care  .
Consistent with industry standards, 'low voltage' refers to voltages below 1000 V. High voltage is defined here as voltage above 1000 V. Most utilization circuits and equipment operate at voltages lower than 600 V, including common household circuits (110 V) and 220 V in some countries  .
There are four main types of electrical injuries according to their effect on the body: electrocution (fatal), electric shock, burns, and falls (secondary trauma), caused as a result of contact with electrical energy  . Electrocution results when a human is exposed to a lethal amount of electrical energy  .
Almost every part of the body can be injured by electric current  .
Death by high-voltage electrical injuries may occur in a number of cases such as occupational exposure among electricians, linesmen, or other tradesmen, and overhead railway power line contact, and also because of contact of construction equipment with power lines; each situation is associated with a number of features common to most types of high-voltage injury, as well as some features specific to the situation  .
One of the biggest challenges that forensic pathologists face is death because of electrocution. In many cases, gross pathological findings such as Joule burns may be observable, but in many cases - almost half of all cases - no gross pathological findings can be observed  .
When electrocution occurs without detectable body marks as in cases of electrocution in standing water or electrocution in concealed areas of the body that may be accidental or because of torture, there is a dilemma as to which part of the body should be examined for microscopic evidence of current injury  . In deaths caused by electrocution, the presence of skin lesions and pathological examinations of tissue samples obtained during the autopsy usually help to determine the cause of death , .
For this reason, the investigation of possible electrocution requires a careful evaluation of the scene of death and assessment of the electrical safety of the building and any electrical equipment that was used. Meticulous examination of all body surfaces for subtle electrical burns with histological sampling is also necessary  .
The aim of the present study is to detect histopathological and immunohistochemical changes in the heart of albino rats after low-voltage electrocution in an attempt to confirm the diagnosis of electrocution as a possible cause of death.
| Materials and methods|| |
Animal groups and electrocution method
Twenty-six adult male albino Sprague rats weighing 150-200 g were obtained from the animal breeding house in Menoufiya.
Following experimental animals ethical manners and procedures all the rats were housed in a metallic cages for 1 week and kept under constant healthy environmental conditions on nutrients to ascertain their physical well being and to exclude any diseased animals.
The animals were divided randomly into two main groups: control group (I) and experimental group (II).
The control group (I) included 10 rats that were killed by cervical dislocation without any application of electrical current.
The experimental group (II) included 16 rats that were electrocuted until death by a 220 V alternating current (AC) with the points of electrical contact placed on the skin of the left forelimb and the skin of the right hind limb.
All the animals in the experimental group (II) were electrocuted using an electrical energy transfer device that consisted of a double copper cable with a pair of ends. One was peeled 1 cm in length and the other was connected to an electrical energy source (delivering the usual household AC of 220 V). The animals were fixed on a plate. The peeled cable was kept in contact with the animals' skin by firm manual pressure. Tissue samples from the control and the experimental group were obtained from the heart for histopathological and immunohistochemical studies.
Methods of histopathological and immunohistochemical studies
Paraffin blocks of the collected hearts were prepared using the Jaffe method  . Sections of 6 μm thickness were stained by hematoxylin and eosin for histopathological examination , .
The expression of caspase-3 was detected in the tested tissues after dissection by immunohistochemistry staining. The immunostaining procedure was performed according to the methods described by Ramos-Vera  and Joyner and Wall  .
Paraffin sections of 4 mm thickness were obtained using a microtome. They were mounted at 37°C overnight, and then deparaffinized and rehydrated. The endogenous peroxidase activity was blocked by 3% hydrogen peroxide in water. Tissue sections were covered immediately with two drops of protein blocking reagents to suppress nonspecific binding of immunoglobulin.
Immunohistochemical staining was performed by placing one or two drops of caspase-3 antibody on each section. Slides were kept horizontal in a humid chamber and incubated overnight at room temperature. Excess reagent was removed and the slides were rinsed in two changes of PBS. Then, one or two drops of link antibody and labeling reagent were added to each section. Slides were incubated in a humid chamber at room temperature for 30 min and then rinsed in two changes of PBS for 5 min. The antigen was finally localized by the addition of DAB chromogen, and then slides were washed in distilled water for 5 min. The slides were counterstained by Mayer's hematoxylin, dehydrated, and finally mounted.
Cellular localization and interpretation of the expression of caspase-3
Cellular localization was predominantly cytoplasmic, with some nuclear staining.
A brown nucleus and brown particles in the cytoplasm of the experimental tissues indicated a positive expression of caspase-3.
| Results|| |
The heart of the control group (I) showed cardiac muscle fibers running in different directions containing an acidophilic sarcoplasm and central pale oval nuclei; a negative immune reaction for caspase-3 was also observed ([Figure 1] and [Figure 2]).
|Figure 1 High-power photomicrograph of a section of the heart of a control rat showing cardiac muscle fibers running in different directions with an acidophilic cytoplasm and central pale oval nuclei (arrows).|
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|Figure 2 High-power photomicrograph of a section of the heart of a control rat showing a negative caspase-3 reaction|
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Microscopic examination of the heart specimens of the rats of electrocuted groups (II) showed areas of interstitial hemorrhage. Some cardiac myocytes appeared necrotic and fragmented. The nuclei were square or rounded in some areas. Myocardial waviness and contraction bands were also observed in other areas ([Figure 3], [Figure 4], [Figure 5], [Figure 6]). A positive immune reaction for caspase-3 was also observed in the form of a brown nucleus and brown particles in the cytoplasm, which were detected in the cytoplasm and some nuclei of a few cardiac muscle fibers compared with the control group ([Figure 7]).
|Figure 3 High-power photomicrograph of a section of the heart of the electrocuted group showing areas of interstitial hemorrhage (green arrows) and rounded or square nuclei (black arrows).|
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|Figure 4 High-power photomicrograph of a section of the heart of the electrocuted group showing areas of necrosis (black arrows), interstitial hemorrhage (red arrow), and fragmentation (green arrows).|
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|Figure 5 High-power photomicrograph of a section of the heart of the electrocuted group showing some rounded nuclei (black arrows), contraction band (red arrows), and fragmentation (green arrows).|
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|Figure 6 High-power photomicrograph of a section of the heart of the electrocuted group showing rounded or square nuclei (green arrows) and waviness (red arrows).|
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|Figure 7 High-power photomicrograph of a section of the heart of the electrocuted group showing a positive caspase-3 reaction in the cytoplasm and nuclei of some cardiac myocytes (arrows).|
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| Discussion|| |
It is a challenging forensic task to determine the cause of death in an electrocuted victim without detectable current marks on the skin  .
In forensic practice, there are many cases where the victim has died of electrocution, but no electric mark can be detected  .
It is very difficult to determine whether an individual died because of electrocution or not. To find an effective means of diagnosing these cases, forensic pathologists have made several attempts to resolve this problem  .
The rats in the experimental group (II) were electrocuted until death by a 220 V AC with the points of electrical contact placed on the skin of the left forelimb and the skin of the right hind limb, allowing the current to pass through the chest and thus affecting the heart.
This is in accordance with Wright and Davis  , who concluded that AC may affect the heart and produce ventricular fibrillation if the path of the current involves passage through the chest. This may occur when the current flows from the arm to the leg, arm to arm, or head to arm or leg.
In terms of the histopathological changes in the cardiac muscle in this study, there were areas of interstitial hemorrhage. Some cardiac myocytes appeared necrotic and fragmented. The nuclei were square or rounded in some areas. Myocardial waviness and contraction bands were also observed in other areas in the rats of the electrocuted group (II).
Necrosis, contraction bands, interstitial hemorrhage, and waviness have been reported previously by Hackel and Jennings  , who verified that necrosis, contraction bands, interstitial hemorrhage, and waviness are microscopic findings of infarcts and ischemic changes of the heart because of effects on heart vasculature, with subsequent impairment in heart blood and oxygen supplies.
The necrosis and contraction bands can also be attributed to cardiac ischemia because of electric current-induced vascular injury as shown previously by Rodríguez-Sinovas et al.  , who concluded that contraction bands and necrosis are considered to arise because of a calcium-dependent mechanism, which is an activation of the contractile machinery of the cell by its usual mechanism, calcium, which is in excess because of ischemia.
These changes can also be attributed to the direct effect of an electric current on the cell membrane, leading to cell damage, as has been reported previously by Leibovici et al.  , who reported that the current destroys the cells by damaging membrane integrity and altering membrane resting potentials, the consequences of which are an influx of solutes and water, cellular edema, and eventually irreversible cellular damage. This process is known as electroporation.
These findings are in agreement with those of Xenopoulos et al.  and Tuttnauer et al.  , who reported in their reviews that the myocardium is damaged by electrical current. The pathological appearance includes myocardial hemorrhage, waviness, coagulative necrosis, and contraction band necrosis and myolysis. Injured cells can be seen adjacent to seemingly unharmed ones. This patchy distribution of injury can result in arrhythmogenicity.
Also, the results were found to be in agreement with those of Fineschi et al.  , who confirmed that segmentation of the myocardial cells and/or widening of the intercalated discs and associated group of hypercontracted myocardial cells with 'square' nuclei in line with hyperdistended ones were observed in the heart sections in a fatal electrocution case.
Myocyte hypercontraction and square nuclei were also observed in the myocardium of an individual who died because of electrocution, examined by Franchet et al.  , and they also reported that the pathological examination indicated an ischemic and hemorrhagic aspect of the heart with features of ventricular fibrillation. The histopathological examination provided some information, which, added to the accident investigation data and the autopsy findings, enabled to propose some hypothesis on the mechanism of death by electrocution.
Fineschi et al.  reported morphological findings in 21 fatal electrocutions, the heart characterized by a break-up of myocardial fibers (MFB). They used the term MFB to include the following histological patterns: bundles of distended myocardial cells alternating with hypercontracted ones. In the latter group of cells, there is also widening or rupture (segmentation) of the intercalated discs. Myocardial nuclei in the hypercontracted cells assume a 'square' aspect rather than the ovoid morphology observed in distended myocytes.
The MFB described could be interpreted as the morphologic counterpart of a terminal dysfunction ending in ventricular fibrillation  .
Immunohistochemical results also support histopathological findings (necrosis or apoptosis). There was a positive immune reaction for caspase-3 detected in the cytoplasm and some nuclei of some cardiac muscle fibers in the rats of the electrocuted group (II) compared with the control group. The positive immune reaction for caspase-3 could be attributed to its important role in cell apoptosis  .
This is in agreement with Armstrong et al.  , who concluded that caspase-3 is activated during programmed cell death (apoptosis). Caspases can be divided into initiator and effective subgroups. The apoptotic phenotype typically requires activation of one or more effector caspases such as caspase-3, caspase-6, and caspase-7.
In the setting of electrical injury, the formation of pores in the process of electroporation probably allows calcium influx into cytoplasm, thereby triggering apoptosis or necrosis of the cell , .
According to Wang et al.  , in the antemortem electrical injury groups, the expression of caspase-8 was positive in the brain, heart, liver, and kidney. The expression of caspase-8 was negative in rats that were electrified after death. He concluded that caspase-8 can be considered an index in identifying electrical injury and distinguishing between antemortem and postmortem electrical injuries.
As both caspase-3 and caspase-8 are involved in the mechanism of the same process(apoptosis), we used caspase-3 in the present study as it is less expensive and more easily available than caspase-8.
Caspase-8 can be considered a 'preexecutioner', whereas caspase-3 can be considered one of the 'executioners' in the apoptosis process. Many studies have implicated that caspase-3 is associated with the induction of apoptosis. Activation of caspase-3 occurs in response to a variety of apoptotic inducers  .
| Conclusion|| |
This study concluded that the histopathological changes and immunohistochemical findings, besides the circumstantial evidence and external marks that may be found at autopsy, may provide a possible means of confirming the diagnosis of deaths caused by electrocution in suspected cases associated with limited external findings. Thus, it is advisable to use these techniques routinely in examinations and for the diagnosis of all cases suspected to have died by electrocution. The role of caspase-3 in identifying electrical injuries, especially in humans, and discriminating between antemortem and postmortem injuries should be investigated widely.
| Acknowledgements|| |
Conflicts of interest
There are no conflicts of interest.
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