On the molecular mechanisms implicated in the bipolar cancellation of membrane electroporation.

Bipolar cancellation is the phenomenon in which the permeability of cell membranes subjected to high intensity short pulsed electric field (ns-µs range) is reduced or eliminated when the system is subjected to bipolar instead of monopolar pulses. Although several studies have tried to explain bipolar cancellation, the underlying mechanisms remain unclear. Very few articles study bipolar cancellation by means of molecular dynamics (MD) simulation. In this paper, we investigated the molecular mechanisms underlying the difference in electroporation induced by bipolar and monopolar picosecond electric pulses (EPs) using MD simulation. The electric field gradients and electric forces on water molecules of the two pulses were analyzed in detail for the first time. For a certain pulse width, when the field intensity is relatively small, the direction of bipolar electric force on the interfacial water molecule reverses as the bipolar EPs reverse, while the electric force on interfacial water molecules of the cathode side remains in the same direction as that of applied monopolar EPs. The bipolar electric force reversal delays the water protrusion and increases the pore formation time. Therefore, this phenomenon could correspond to bipolar cancellation. When the field intensity is relatively large, although the bipolar electric force direction still reverses, half of the total time of the monopolar EPs has no electric fields. The electric forces of monopolar no-field half-cycles are much smaller than those of the bipolar EPs. Therefore, the pore formation time of bipolar EPs reduces, and this phenomenon is called bipolar enhancement. The occurrence of bipolar cancellation or bipolar enhancement depends on conditions such as the width and intensity of the pulse.

Effect of the electric field at 50 Hz and variable intensities on biochemical markers in the honey bee's hemolymph.

The amount of artificial electromagnetic fields of various parameters in the honey bee's environment increases globally. So far, it had been proven that exposure to an E-field at 50 Hz can cause changes in bee's behavior, alter the activity of proteases, and enzymatic antioxidants. Due to the potentially harmful effect of this factor on honey bees, we decided to investigate the activity of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and alkaline phosphatase (ALP), and the concentration of albumin and creatinine in bee's hemolymph after exposure to 50 Hz E-field. Honey bee workers were placed in wooden cages (200 × 150 × 70 mm) and exposed to the 50 Hz E-field with the intensity of <1, 5.0, 11.5, 23.0, or 34.5 kV/m for 1, 3, 6, or 12h. A homogeneous 50 Hz E-field was generated in the form of a plate capacitor. Hemolymph samples for analysis were taken immediately after the end of exposure to the E-field from 100 bees from each group. According to our study, the activity of AST, ALT, and ALP in honey bees' hemolymph decreased after exposure to 50 Hz E-field with various intensities. The decrease in AST, ALT, and ALP activity intensified with prolonged exposure time. 50 Hz E-field may cause the impairment of crucial metabolic cycles in the honey bees' organism (such as the citric acid cycle, ATP synthesis, oxidative phosphorylation, ß-oxidation). Moreover, exposure to E-Field altered the concentration of creatinine and albumin, which are important non-enzymatic antioxidants. Such changes may indicate a disturbance in protein metabolism and increased muscle activity.

Variable response to electric shark deterrents in bull sharks, Carcharhinus leucas.

Although relatively rare, human-shark interactions and sharks bites are increasing globally, which has led to the development of various mitigation measures. Electric shark deterrents (ESDs) have, so far, been the most effective personal deterrents, but have only been scientifically tested on one of the species most frequently responsible for shark bites, i.e. white shark (Carcharodon carcharias). We tested the effectiveness of five ESDs (E-Shark Force, NoShark, Rpela v2, Freedom + Surf, Freedom + Surf-Shortboard) on bull sharks, Carcharhinus leucas, over a period of 21 days in September 2019, in New Caledonia. Standardised bait was attached 30 cm below an experimental board that had an active ESD for up to 15 min, or until a bull shark touched the bait or the board. We compared the numbers of baits taken, numbers of passes and reactions around the board, as well as the distance between the sharks and the board among ESDs and against a control board with bait and no active ESD. The Freedom + Surf was the most effective ESD, reducing the amounts of baits taken by 42.3%, while the Rpela v2 and Freedom + Surf-Shortboard also significantly reduced the number of baits taken by 16.5% and 16.2% respectively. Mean distance between sharks and the bait was not affected by the ESDs, but the number of approaches and the proportion of reactions were both significantly higher when the Freedom + Surf was active compared to other ESDs. The effectiveness of all ESDs decreased over time, with the likelihood of the bait being taken increasing and the number of approaches and distance between sharks and the bait decreasing. Our findings show that the ability of ESDs to deter bull shark varies between products, with the Freedom + Surf resulting in the most behavioural changes, followed by the Rpela v2 and Freedom + Surf-Shortboard. However, none of the products tested completely stopped sharks from taking the bait.

Determination of metallization with energy-dispersive X-ray fluorescent spectrometry in experimental electric injury.

We investigated the application of energy-dispersive X-ray fluorescent spectrometry (EDX) analysis to the detection of aluminum (Al), tin (Sn) and zinc (Zn) as the electric conductor in experimental electrical injury. Experimental electrical injury was caused by exposure to alternating current at 100 V for 10 s. The peaks of Al, Sn, and Zn were detected by EDX in formalin-fixed skin samples of each current exposure group. Histological examination revealed blister formation in all samples of each current exposure group. EDX analysis technique can be applied to detect Al, Sn, and Zn as the electric conductor, and is useful in the diagnosis of electrocution.

Nanosecond pulsed electric fields induce the integrated stress response via reactive oxygen species-mediated heme-regulated inhibitor (HRI) activation.

The integrated stress response (ISR) is one of the most important cytoprotective mechanisms and is integrated by phosphorylation of the α subunit of eukaryotic translation initiation factor 2 (eIF2α). Four eIF2α kinases, heme-regulated inhibitor (HRI), double-stranded RNA-dependent protein kinase (PKR), PKR-like endoplasmic reticulum kinase (PERK), and general control nonderepressible 2 (GCN2), are activated in response to several stress conditions. We previously reported that nanosecond pulsed electric fields (nsPEFs) are a potential therapeutic tool for ISR activation. In this study, we examined which eIF2α kinase is activated by nsPEF treatment. To assess the responsible eIF2α kinase, we used previously established eIF2α kinase quadruple knockout (4KO) and single eIF2α kinase-rescued 4KO mouse embryonic fibroblast (MEF) cells. nsPEFs 70 ns in duration with 30 kV/cm electric fields caused eIF2α phosphorylation in wild-type (WT) MEF cells. On the other hand, nsPEF-induced eIF2α phosphorylation was completely abolished in 4KO MEF cells and was recovered by HRI overexpression. CM-H2DCFDA staining showed that nsPEFs generated reactive oxygen species (ROS), which activated HRI. nsPEF-induced eIF2α phosphorylation was blocked by treatment with the ROS scavenger N-acetyl-L-cysteine (NAC). Our results indicate that the eIF2α kinase HRI is responsible for nsPEF-induced ISR activation and is activated by nsPEF-generated ROS.

Cyclopentane rings in hydrophobic chains of a phospholipid enhance the bilayer stability to electric breakdown.

Archaeal lipids ensure unprecedented stability of archaea membranes in extreme environments. Here, we incorporate a characteristic structural feature of an archaeal lipid, the cyclopentane ring, into hydrocarbon chains of a short-chain (C12) phosphatidylcholine to explore whether the insertion would allow such a lipid (1,2-di-(3-(3-hexylcyclopentyl)-propanoate)-sn-glycero-3-phosphatidylcholine, diC12cp-PC) to form stable bilayers at room temperature. According to fluorescence-based assays, in water diC12cp-PC formed liquid-crystalline bilayers at room temperature. Liposomes produced from diC12cp-PC retained calcein for over a week when stored at +4 °C. diC12cp-PC could also form model bilayer lipid membranes that were by an order of magnitude more stable to electrical breakdown than egg PC membranes. Molecular dynamics simulation showed that the cyclopentane fragment fixes five carbon atoms (or four C-C bonds), which is compensated by the higher mobility of the rest of the chain. This was found to be the reason for the remarkable stability of the diC12cp-PC bilayer: restricted conformational mobility of a chain segment increases the membrane bending modulus (compared to a normal hydrocarbon chain of the same length). Here, higher stiffness practically does not affect the line tension of a membrane pore edge. Rather it makes it more difficult for diC12cp-PC to rearrange in order to line the edge of a hydrophilic pore; therefore, fewer pores are formed.

Detection of intracellular biomarkers in viable cells using millisecond pulsed electric fields.

Reversible electroporation is a temporary permeabilization of cell membrane through the formation of transient pores created by short high voltage electric pulses. This method has numerous applications in biology and biotechnology and has become an important technique in molecular medicine. Reversible electroporation is usually used to transfer macromolecules into the cells. However, the delivery of large molecules such as proteins into cells without loss of cell viability remains a challenge. In our study, we investigated whether electroporation can be used for this purpose. The study was performed with the primary mouse splenocytes and Jurkat cell line. The electroporation efficacy was evaluated by flow cytometry. We used the reversible electroporation for intracellular marker detection investigating antibody and fluorescein-conjugated dextran transfer efficiency, cell viability and metabolic activity. We have found that reversible electroporation parameters can be optimized for efficient transfer of large molecules such as antibodies/proteins into live cells without a significant loss of cell viability. We conclude that a well-established and relatively easy method of reversible electroporation can be adjusted to detect intracellular biomarkers in viable cells. This is a new approach on how electroporation could be utilised in medicine and biological research to detect rare subpopulations of cells that produce specific markers and to keep cells viable. This would allow the use of these rare subpopulations of isolated cells for further research and personalized medicine.

Fogo em campo cirúrgico - Medidas preventivas para cirurgia palpebral segura / Operating room fire prevention - preventive measures for safe eyelid surgery

Resumo Fogo em campo cirúrgico durante cirurgia palpebral é uma complicação intra-operatória que é dramática tanto para o paciente quanto para a equipe médica. Relatamos um caso de acidente cirúrgico durante cirurgia palpebral onde o paciente sofreu queimadura de supercílio. Houve interação entre o oxigênio usado para sedação (máscara aberta) e uma fonte de ignição representada pelo cautério monopolar. Embora o paciente tenha apresentado boa evolução clínica com recuperação total da lesão cutânea, este caso é um alerta para se evitar tais tipo de ocorrência. Ressaltamos neste trabalho quais as condições implicadas e o modo de prevenção.

Abstract Fire in the surgical field during eyelid surgery is an intra-operative complication that is dramatic for both the patient and the medical staff. It's being reported a case of surgical accident during eyelid surgery where the patient suffered a brow burn. There was interaction between the oxygen used for sedation (open mask) and a source of ignition represented by monopolar cautery. Although the patient presented good clinical evolution with complete recovery of the cutaneous lesion, this case is an alert to avoid such type of occurrence. This work highlights the conditions involved and the way of prevention.

Electric shock-induced cardiac injuries requiring surgical intervention: Case series and a brief review.

BACKGROUND: Electric shock-induced cardiac injuries, such as myocardial infarction, thrombosis, and dissection, are rare. Few cases have been previously reported. The right coronary artery is most often affected because of its proximity to the chest wall. AIMS: To study the extend of electrical injuries on cardiac tissues and its surgical management. MATERIALS AND METHODS: We conducted a retrospective study on our patients in the last five years, looking for cardiac electrical injuries treated surgically in our department, we identified three cases. RESULT: Our three-case series, reported herein, showed that multiple cardiac tissues are susceptible to electrical injuries, specifically the left coronary artery, inferior vena cava, and right ventricular free wall. In our series, the first patient was a 32-year-old man with triple vessel thrombosis and dissection who survived the electric shock. The second patient was a 23-year-old man who had an inferior vena cava burn and bruising; his heart was used for transplantation. After the transplant, the recipient had a left coronary artery dissection and underwent coronary artery bypass grafting. The third patient was a 30-year-old man (potential heart donor) who had a hematoma of the right ventricular free wall, possible coronary artery dissection, inferior vena cava bruising, and tissue damage. His heart was not used for transplant because of quality concerns. CONCLUSION: We recommend that any person who sustains high voltage (500 V or more) electric shock should be evaluated carefully in the emergency department, including with echocardiography and cardiac catheterization, if indicated, to determine the extent of the injury and the viability of the heart, for patients who do not survive as a donor organ.

Analysis of 4 Cases of Electrocution due to Direct Current Electronic Hunter.

ABSTRACT: Objective To summarize the characteristics of cases of electrocution due to direct current （DC） electronic hunter, and to provide references for forensic identification. Methods Four cases of electrocution due to DC electronic hunter were collected. Statistical analysis was carried out from the perspective of the scene and electric marks distribution, damage characteristics and histopathological changes. Results All the 4 cases of electrocution were accidental events. There were multiple electric marks, most of which were located in the lower limbs with serious damage. Some strip type electric marks were visible. Conclusion The distribution, morphological characteristics and severity of the electric marks caused by DC electronic hunter are different from those of the ordinary low-voltage alternating current damage. It is alerting that there would be actions of destroying the scene and abandoning the corpse in such cases.

Sleep timing and duration in indigenous villages with and without electric lighting on Tanna Island, Vanuatu.

It has been hypothesized that sleep in the industrialized world is in chronic deficit, due in part to evening light exposure, which delays sleep onset and truncates sleep depending on morning work or school schedules. If so, societies without electricity may sleep longer. However, recent studies of hunter-gatherers and pastoralists living traditional lifestyles without electricity report short sleep compared to industrialized population norms. To further explore the impact of lifestyles and electrification on sleep, we measured sleep by actigraphy in indigenous Melanesians on Tanna Island, Vanuatu, who live traditional subsistence horticultural lifestyles, in villages either with or without access to electricity. Sleep duration was long and efficiency low in both groups, compared to averages from actigraphy studies of industrialized populations. In villages with electricity, light exposure after sunset was increased, sleep onset was delayed, and nocturnal sleep duration was reduced. These effects were driven primarily by breastfeeding mothers living with electric lighting. Relatively long sleep on Tanna may reflect advantages of an environment in which food access is reliable, climate benign, and predators and significant social conflict absent. Despite exposure to outdoor light throughout the day, an effect of artificial evening light was nonetheless detectable on sleep timing and duration.

Filtering of neurophysiologic signals.

Clinical neurophysiologic signals cover a broad range of frequencies. Filters help to emphasize waveforms that are of clinical or research interest and to mold their frequency characteristics to suit the purpose of the investigation. Some frequency content is obvious and well known, such as the alpha rhythm (8-11Hz) or spindles (12-14Hz) in the EEG. Other frequencies are not initially discriminable from background activity and require filtering in order to examine them, such as high-frequency oscillations (80-500Hz) in EEG and brainstem auditory evoked potentials (100-3000Hz). Often used to mitigate the effects of background noise or artifact, filters can be used specifically to attenuate unwanted frequencies, such as mains interference (50 or 60Hz) and electrode offset potential (<0.1Hz). For digital instrumentation, an antialiasing filter (below Nyquist) is always needed prior to sampling by the analog-to-digital converter. Once the signals are in the digital realm, sophisticated filtering operations can be carried out post hoc; but in order not to be misled, the neurophysiologist must always bear in mind the effect of filtering on the physiological waveform.

Electrical safety.

Since the purpose of clinical neurophysiology testing is to record the electrical activity of the nervous system, and often to electrically stimulate the peripheral or central nervous system (for evoked potentials, nerve conduction studies, etc.), these tests by their very nature demand an excellent electrical connection to the patient. This direct electrical connection by definition puts the patient at increased risk of electrical shock. When patients suffer from other nonneurological disorders that also require equipment to be attached to or inserted into their body, the additional and more direct electrical pathways to the heart make them even more vulnerable, especially when undergoing monitoring in the operating room or intensive care unit. Although we depend on the hospital's construction and utilities to follow appropriate regulations (the National Electrical Code in the United States) and on the vendors to sell only safe equipment (approved by the Food and Drug Administration in the United States), there may exist combinations of equipment and connections that put the patient at risk of injurious or fatal electrical shock. Regular testing and safe practices, informed by a scientific understanding of the risks, are the responsibilities of the healthcare providers in order to protect the patient from harm from electricity.

GDNF-ADSCs-APG embedding enhances sciatic nerve regeneration after electrical injury in a rat model.

The pluripotency of adipose-derived stem cells (ADSCs) makes them appropriate for tissue repair and wound healing. Owing to the repair properties of autologous platelet-rich gel (APG), which is based on easily accessible blood platelets, its clinical use has been increasingly recognized by physicians. The aim of this study was to investigate the effect of combined treatment with ADSCs and APG on sciatic nerve regeneration after electrical injury. To facilitate the differentiation of ADSCs, glial cell line-derived neurotrophic factor (GDNF) was overexpressed in ADSCs by lentivirus transfection. GDNF-ADSCs were mingled with APG gradient concentrations, and in vitro, cell proliferation and differentiation were examined with 5-ethynyl-2'-deoxyuridine staining and immunofluorescence. A rat model was established by exposing the sciatic nerve to an electrical current of 220 V for 3 seconds. Rat hind-limb motor function and sciatic nerve regeneration were subsequently evaluated. Rat ADSCs were characterized by high expression of CD90 and CD105, with scant expression of CD34 and CD45. We found that GDNF protein expression in ADSCs was elevated after Lenti-GDNF transfection. In GDNF-ADSCs-APG cultures, GDNF was increasingly produced while tissue growth factor-ß was reduced as incubation time was increased. ADSC proliferation was augmented and neuronal nuclei (NeuN) and glial fibrillary acidic protein (GFAP) expression were upregulated in GDNF-ADSCs-APG. In addition, limb motor function and nerve axon growth were improved after GDNF-ADSCs-APG treatment. In conclusion, our study demonstrates the combined effect of ADSCs and APG in peripheral nerve regeneration and may lead to treatments that benefit patients with electrical injuries.

A Metamodeling Framework for Quantifying Health Damages of Power Grid Expansion Plans.

In this paper, we present an analytical framework to establish a closed-form relationship between electricity generation expansion planning decisions and the resulting negative health externalities. Typical electricity generation expansion planning models determine the optimal technology-capacity-investment strategy that minimizes total investment costs as well as fixed and variable operation and maintenance costs. However, the relationship between these long-term planning decisions and the associated health externalities is highly stochastic and nonlinear, and it is computationally expensive to evaluate. Thus, we developed a closed-form metamodel by executing computer-based experiments of a generation expansion planning model, and we analyzed the resulting model outputs in a United States Environmental Protection Agency (EPA) screening tool that approximates the associated human health externalities. Procedural guidance to verify the accuracy and to select key metamodel parameters to enhance its prediction capability is presented. Specifically, the metamodel presented in this paper can predict the resulting health damages of long-term power grid expansion decisions, thus, enabling researchers and policy makers to quickly assess the health implications of power grid expansion decisions with a high degree of certainty.

Distinct and independent dielectrophoretic behavior of the head and tail of sperm and its potential for the safe sorting and isolation of rare spermatozoa.

Often, in semen samples with minute amounts of sperm, even the single spermatozoon required to fertilize an oocyte cannot be found in the ejaculate. This is primarily because currently, sperm is generally searched for manually under a microscope. In this study, dielectrophoresis (DEP) was investigated as an alternative automated technique for sorting sperm cells. Using a quadrupolar electrode array it was shown that the head and tail of the sperm had independent and unique crossover frequencies corresponding to the transition of the DEP force from repulsive (negative) to attractive (positive). These surprising results were further analyzed, showing that the head and tail have their own distinct electrical properties. This significant result allows for the sperm's head, which contains the DNA, to be distanced from potentially damaging high electric fields using negative DEP while simultaneously manipulating and sorting the sperm using the positive DEP response of the tail. A proof of concept sorting chip was designed and tested. The low crossover frequency of the tail also allows for the use of a higher conductivity, and thus more physiological, medium than the conventional DEP solutions. Although more research is required to design and optimize an efficient, user-friendly, and high-throughput device, this research is a proof of concept that DEP has the potential to automate and improve the processing of semen samples, especially those containing only rare spermatozoa.

Leakage current from transvenous and subcutaneous implantable cardioverter defibrillators (ICDs): A risk to the rescuer?

BACKGROUND: Implantable cardioverter-defibrillators (ICDs) are a well-established therapy for patients at risk of life-threatening ventricular arrhythmias. With rising implant rates, the risk of a rescuer performing chest compressions during discharge is increasing, leading to concerns over rescuer safety from the resultant leakage current. More recently, subcutaneous ICDs (S-ICD) have been developed, which utilise a higher energy and more superficial electrodes compared with transvenous ICDs (T-ICD), raising safety concerns further. OBJECTIVE: We measured the current a rescuer would potentially receive from T-ICDs and S-ICDs if they were in contact with the patient at the time of ICD discharge to assess its magnitude in relation to international safety standards. METHODS: Surface voltages adjacent to ICD electrodes were measured on patients undergoing defibrillation threshold checks. Rescuer current was then calculated assuming a total rescuer circuit impedance of 1696 Ω. RESULTS: Twenty-five patients were recruited. Rescuer current from S-ICDs was significantly higher than those from T-ICDs (S-ICD: Median RMS 135 mA range 91 mA-164 mA, T-ICD: Median RMS 31 mA, range 9 mA-75 mA, P < 0.0001). Surface voltages (median RMS) to which the rescuer is likely to be exposed are higher when performing chest compressions from the patient's left side compared with the right (127 V vs 67 V respectively, 95% CI of difference -34 V to -67 V, P < 0.0001). CONCLUSIONS: Rescuers performing chest compressions on ICD patients are at risk from leakage current, particularly from S-ICDs. Chest compressions should be performed from the opposite side to the ICD to reduce rescuer risk.

The effects of electric power lines on the breeding ecology of greater sage-grouse.

Anthropogenic infrastructure can negatively affect wildlife through direct mortality and/or displacement behaviors. Some tetranoids (grouse spp.) species are particularly vulnerable to tall anthropogenic structures because they evolved in ecosystems void of vertical structures. In western North America, electric power transmission and distribution lines (power lines) occur in sagebrush (Artemisia spp.) landscapes within the range of the greater sage-grouse (Centrocercus urophasianus; sage-grouse). The U.S. Fish and Wildlife Service recommended using buffer zones near leks to mitigate the potential impacts of power lines on sage-grouse. However, recommended buffer distances are inconsistent across state and federal agencies because data are lacking. To address this, we evaluated the effects of power lines on sage-grouse breeding ecology within Utah, portions of southeastern Idaho, and southwestern Wyoming from 1998-2013. Overall, power lines negatively affected lek trends up to a distance of 2.7 and 2.8 km, respectively. Power lines died not affect lek persistence. Female sage-grouse avoided transmission lines during the nesting and brooding seasons at distances up to 1.1 and 0.8 km, respectively. Nest and brood success were negatively affected by transmission lines up to distances of 2.6 and 1.1 km, respectively. Distribution lines did not appear to affect sage-grouse habitat selection or reproductive fitness. Our analyses demonstrated the value of sagebrush cover in mitigating potential power line impacts. Managers can minimize the effects of new transmission power lines by placing them in existing anthropogenic corridors and/or incorporating buffers at least 2.8 km from active leks. Given the uncertainty we observed in our analyses regarding sage-grouse response to distribution lines coupled with their role in providing electric power service directly to individual consumers, we recommend that buffers for these power lines be considered on a case-by-case basis. Micrositing to avoid important habitats and habitat reclamation may reduce the potential impacts of new power line construction.

Evaluating exposure from electric fields in a high voltage switchyard according to the EU directive.

An assessment according to Directive 2013/35/EU of exposure in a 400 kV switchyard has been performed. Part of the body was exposed to electric field strength above the high action level. We therefore performed simulations of the electric fields induced in the body to assess these accoding to the exposure limit values (ELVs). The simulations show that as long as the body is not grounded nor touching any grounded metallic objects, worker exposure is compliant with the directive. When grounded metallic objects are touched with hand or foot the ELV are exceeded. The ELV is exceeded already at very low contact currents (2-3 µA) in the finger. If not appropriate measures are taken, this would lead to a severe limitation of the work tasks that can be performed in switchyards.