Sulfide Poisoning Research Articles

Oxidative weathering on the continent and seawater upwelling along the passive continental margin promoted widespread phosphorite formation at the Neoproterozoic-Cambrian boundary in South China

The latest Proterozoic to early Cambrian is characterized by major global phosphogenic events and the diversification of complex multicellular life. However, the feedback mechanism of atmospheric oxidation and upwelling processes to form voluminous phosphorite deposits is unclear. South China is a key example of the sedimentary spectrum related to the Neoproterozoic to Early Cambrian bloom of oxygenic photosynthesis, with alginite deposits (sapropelite; “stone coal”), barite, polymetallic black shales and phosphorites along the passive continental paleo-margin of the Yangtze craton. Here, we present a comprehensive geochemical analysis of drill core samples from the Zhijin phosphorite deposit, including Cr isotope, Fe speciation, and bulk elemental composition of dolostone, phosphorite and black shale from the Ediacaran to Early Cambrian sequence. The positively fractionated δ53Cr values of 0.11 to 1.81 ‰ of leachates from Ediacaran dolostone and Terreneuvian phosphorite indicate intensive oxidative terrestrial weathering. The phosphorite samples exhibit REE distribution patterns similar to modern seawater and strongly negative Ce anomalies (0.47–0.61), suggesting an oxic, open ocean environment. In contrast, the absence of Ce anomaly, high FeHR/FeT, and Fepy/FeHR ratios, enhanced redox-sensitive element concentrations, high Mo/TOC and TS/TOC, and high molar Corg:P ratios suggest euxinic to anoxic conditions for the overlying black shale sedimentation in a restricted sedimentary marine environment. Bulk-rock shale samples retain the positively fractionated Cr isotope pattern. The dramatic change from oxic to anoxic conditions aligns with the fossil record, which shows a proliferation of small shelly fossils in the phosphorite and their extinction in the overlying black shales, likely by hydrogen sulfide poisoning. We infer that nutrient-rich, oxidized upwelling seawater transported phosphorus and other nutrients to the photic zone, from where organic matter settled down to the seafloor and formed thick phosphorite beds at the oxic-anoxic boundary at and below the seafloor. Our study highlights that atmospheric and seawater oxygenation accelerated the Early Cambrian bio-diversification, and the subsequent restricted basin situation is responsible for the extinction at the Neoproterozoic-Cambrian boundary.

Tarnished jewellery and skin - a subtle external marker indicating exposure to hydrogen sulfide.

A 39-year-old woman was found lying in the rear of a car at her home address. A smell of rotten eggs was noted and bottles of brick, tile and paver cleaner and lime sulfur were found in the rear of the vehicle. Suicide notes were found in the house. At autopsy there was no evidence of significant trauma with black tarnishing of a silver-coloured ring and a silver-coloured necklace noted with staining of the underlying skin, in keeping with a chemical reaction between hydrogen sulfide and silver. Internally the most significant finding was unusual greenish discolouration of the gray matter of the external and cut surfaces of the cerebral hemispheres, cerebellum and brain stem. No other organs had this discoloration. Death was attributed to hydrogen sulfide poisoning. Skin discoloration from silver jewellery may represent a subtle external marker for lethal or non-lethal hydrogen sulfide exposure.

Forensic analysis of hydrogen sulfide poisoning cases: Innovative LC-MS/MS methodology for accurate detection in human blood

Identification of hydrogen sulfide poisoning cases has long been a challenging issue in the field of forensic science. Due to the relatively limited histopathological features associated with hydrogen sulfide poisoning, traditional anatomy faces difficulties in accurately determining such cases. Additionally, existing detection methods have inherent limitations, including complex analytical processes and low sensitivity. This research uses the principle of the reaction between triazine and hydrogen sulfide to generate thiadiazine to measure hydrogen sulfide levels in the blood, applying this method to practical case examinations. A 0.2 mL blood sample is taken and diluted with 0.8 mL saturated borax solution. In a test tube, 1 mL acetonitrile solution containing 0.1 % formic acid is taken, followed by the sequential addition of 0.1 mL diluted solution and 0.1 mL 1 % triazine aqueous solution. After thorough mixing, the mixture is allowed to stand for 30 min, during which hydrogen sulfide undergoes a derivative reaction with triazine, producing thiazine. Subsequently, the sample undergoes centrifugation and membrane filtration, and the resulting solution is analyzed using Liquid Chromatograph Mass Spectrometer. The results reveal a strong linear relationship of hydrogen sulfide within the concentration range of 10 to 2000 ng/mL, with an R2 of 0.9989. The detection limit is 3 ng/mL, and the quantification limit is 10 ng/mL. In six cases of hydrogen sulfide poisoning, the presence of hydrogen sulfide in the blood of all deceased individuals is detected, with concentrations ranging from 0.25 to 0.79 μg/mL. For the first time, this study establishes an LC-MS/MS method for determining hydrogen sulfide in blood, meeting the detection requirements for hydrogen sulfide poisoning cases.

Mass hydrogen sulfide poisoning and the role of forensic medical examination in proving

Introduction. Using the example of practical observation, the article describes the features of mass hydrogen sulfide poisoning, as well as the role of the therapeutic and diagnostic process and forensic medical examination in proving it. 
 The aim of the study was to develop effective principles of a comprehensive forensic expert assessment of a case of mass hydrogen sulfide poisoning, as well as to highlight the leading aspects of the role of the therapeutic and diagnostic process in proving the harm to health caused by an environmental crime.
 Material and methods. The material of the study was a case of mass hydrogen sulfide poisoning of residents of the village of Samorodovo of the Orenburg region, which served as the basis for the introduction of an intermunicipal emergency regime on the territory of Orenburg and the Orenburg region. 35 conclusions of the forensic medical examination, 35 medical histories, 1 conclusion of the forensic environmental examination, 1 indictment and 1 sentence were subjected to retrospective analysis.
 Results. Based on the analysis of the considered case of mass poisoning, it can be concluded that to prove a number of environmental crimes, conducting a forensic environmental examination alone is not enough, since objective medical data on the state of health of the victims are also required to establish circumstances significant for the investigation. In other words, the information necessary for the investigation can be obtained only through the most complete clinical and laboratory-instrumental examination of all victims, followed by a forensic medical assessment of the data obtained.
 Limitations. The conducted research was carried out as part of an initiative research work on the analysis of environmental crimes committed on the territory of the Russian Federation in the period from 2016 to 2021. The analyzed documents were provided by the relevant regional divisions of the Investigative Committee of the Russian Federation by prior agreement and included only materials of criminal cases completed by the investigation.
 Conclusion. The results obtained in the framework of this study clearly demonstrate that in situations like the one described, the presence of even minor diagnostic manifestations of poisoning, and most importantly their objective fixation in medical documentation, allow us to obtain the information necessary to establish the objective truth in the case.

Intratracheal cobinamide (vitamin B12 analog) administration increases survivability in rabbits exposed to a lethal dose of inhaled hydrogen sulfide

Background Hydrogen sulfide is a highly toxic, flammable, and colorless gas. Hydrogen sulfide has been identified as a potential terrorist chemical threat agent in mass-casualty events. Our previous studies showed that cobinamide, a vitamin B12 analog, effectively reverses the toxicity from hydrogen sulfide poisoning. In this study, we investigate the effectiveness of intratracheally administered cobinamide in treating a lethal dose hydrogen sulfide gas inhalation and compare its performance to saline control administration Methods A total of 53 pathogen-free New Zealand White rabbits were used for this study. Four groups were compared: (i) received no saline solution or drug intratracheally (n = 15), (ii) slow drip saline intratracheally (n = 15), (iii) fast drip saline intratracheally (n = 15), and (iv) slow drip cobinamide intratracheally (n = 8). Blood pressure was continuously monitored, and deoxy- and oxyhemoglobin concentration changes were monitored in real-time in vivo using continuous wave near-infrared spectroscopy. Results The mean (± standard deviation) weight for all animals (n = 53) was 3.87 ± 0.10 kg. The survival rates of the slow cobinamide and the fast saline groups were 75 percent and 60 percent, respectively, while the survival rates in the slow saline and control groups were 26.7 percent and 20 percent, respectively. A log-rank (Mantel-Cox) test showed that survival in fast saline and slow cobinamide groups were significantly greater than those of no saline control and slow saline groups (P < 0.05). The slow and no saline control groups were not significantly different (P = 0.59). The slow cobinamide group did significantly better than the slow saline group (P = 0.021). Discussion The ability to use intratracheal cobinamide as an antidote to hydrogen sulfide poisoning is a novel approach to mass-casualty care. The major limitations of this study are that it was conducted in a single species at a single inhaled hydrogen sulfide concentration. Repeated investigations in other species and at varying levels of hydrogen sulfide exposure will be needed before any definitive recommendations can be made. Conclusions We demonstrated that intratracheal cobinamide and fast saline drip improved survival for hydrogen sulfide gas inhalation in rabbit models. Although further study is required, our results suggest that intratracheal administration of cobinamide and fast saline may be useful in hydrogen sulfide mass-casualty events.

Development of an assay for colorimetric and fluorometric detection of H2S.

Hydrogen sulfide is a highly toxic gas that can produce extremely rapid CNS and respiratory depression and sometimes becomes fatal at high concentrations. There is no proven antidote for hydrogen sulfide poisoning. Hence, it is important to reduce the production of H2S in several industries, such as oil and gas refining and mining industries. As a consequence, researchers are always inquisitive about inventing different sensing devices or useful tools to detect H2S selectively in a cost-effective manner. Colorimetric and fluorometric detection methods are the most attractive owing to their simplicity, profitability, ease of understanding, and "on-spot" detection convenience. In this research, we developed some colorimetric and fluorometric chemosensors and established an assay for the easy detection of H2S following a specific mechanism. The sensing mechanisms were well established through exhaustive spectroscopic studies and theoretical calculations. We first synthesized a series of chemosensors using 2-hydroxy naphthaldehyde as a primary fluorophore. The chemosensors were developed by incorporating various electron-releasing and donating groups while keeping the binding site unchanged. Subsequently, we compared their efficiency and binding ability towards H2S with a possible mechanism. The chemosensor was employed through a paper strip for demonstration as an "in-field" device by changing the naked-eye and fluorescence color both in liquid and gas phases.

Detrimental impact of sulfide on the seagrass Zostera marina in dark hypoxia

Sulfide poisoning, hypoxia events, and reduced light availability pose threats to marine ecosystems such as seagrass meadows. These threats are projected to intensify globally, largely due to accelerating eutrophication of estuaries and coastal environments. Despite the urgency, our current comprehension of the metabolic pathways that underlie the deleterious effects of sulfide toxicity and hypoxia on seagrasses remains inadequate. To address this knowledge gap, I conducted metabolomic analyses to investigate the impact of sulfide poisoning under dark-hypoxia in vitro conditions on Zostera marina, a vital habitat-forming marine plant. During the initial 45 minutes of dark-hypoxia exposure, I detected an acclimation phase characterized by the activation of anaerobic metabolic pathways and specific biochemical routes that mitigated hypoxia and sulfide toxicity. These pathways served to offset energy imbalances, cytosolic acidosis, and sulfide toxicity. Notably, one such route facilitated the transformation of toxic sulfide into non-toxic organic sulfur compounds, including cysteine and glutathione. However, this sulfide tolerance mechanism exhibited exhaustion post the initial 45-minute acclimation phase. Consequently, after 60 minutes of continuous sulfide exposure, the sulfide toxicity began to inhibit the hypoxia-mitigating pathways, culminating in leaf senescence and tissue degradation. Utilizing metabolomic approaches, I elucidated the intricate metabolic responses of seagrasses to sulfide toxicity under in vitro dark-hypoxic conditions. My findings suggest that future increases in coastal eutrophication will compromise the resilience of seagrass ecosystems to hypoxia, primarily due to the exacerbating influence of sulfide.

Pharmaceutical stability of methemoglobin-albumin cluster as an antidote for hydrogen sulfide poisoning after one-year storage in freeze-dried form

Long-term stability during storage is an important requirement for pharmaceutical preparations. The methemoglobin (metHb)-albumin cluster, in which bovine metHb is covalently enveloped with an average of three human albumin molecules, is a promising antidote for hydrogen sulfide (H2S) poisoning. In this study, we investigated the pharmaceutical stability of metHb-albumin cluster after storage for one year in solution and as freeze-dried powder. The lyophilized powder of metHb-albumin cluster stored for one year was readily reconstituted in sterile water for injection, yielding a homogeneous brown solution. Physicochemical measurements revealed that the overall structure of the metHb-albumin cluster was still maintained after preservation. Results of the pharmacological study showed that 100 % of the H2S-poisoned mice survived after treatment with the reconstituted solution of metHb-albumin cluster powder. Furthermore, the solution did not cause any toxic reactions. The antidotal efficacy of metHb-albumin cluster for H2S poisoning was preserved in freeze-dried powder form for at least one year.

Pharmaceutical Integrity of Lyophilized Methemoglobin-Albumin Clusters after Reconstitution.

Covalent attachment of a ferric hemoglobin (metHb) core to three human serum albumin molecules to form metHb-albumin clusters has previously been used to develop an antidote for hydrogen sulfide poisoning. Lyophilization is one of the most effective approaches to preserve protein pharmaceuticals with minimum contamination and decomposition. However, there is concern that lyophilized proteins may undergo pharmaceutical alteration on reconstitution. This study investigated the pharmaceutical integrity of metHb-albumin clusters on lyophilization and reconstitution with three clinically available reconstitution fluids, (i) sterile water for injection, (ii) 0.9% sodium chloride injection, and (iii) 5% dextrose injection. The metHb-albumin clusters retained their physicochemical properties and structural integrity on lyophilization and reconstitution with sterile water for injection or 0.9% sodium chloride injection, along with comparable hydrogen sulfide scavenging ability compared to non-lyophilized metHb-albumin clusters. The reconstituted protein completely rescued lethal hydrogen sulfide poisoning in mice. On the other hand, lyophilized metHb-albumin clusters reconstituted with 5% dextrose injection showed physicochemical changes and a higher mortality rate in mice subjected to lethal hydrogen sulfide poisoning. In conclusion, lyophilization represents a potent preservation method for metHb-albumin clusters if either sterile water for injection or 0.9% sodium chloride injection is used for reconstitution.

Retrospective analysis of forensic toxicology data from 2021 to identify patterns of various forensic cases

PurposeKnowing and analyzing the characteristics and trends of forensic toxicology cases in a certain area is particularly important for a local government to establish an effective prevention and control system. The purpose of this work was to summarize data from forensic toxicology cases received by the Academy of Forensic Sciences (AFS) in 2021. MethodsAs requested by the police or according to the details of cases, samples were systematically screened or analyzed by various methods. Liquid chromatography-tandem mass spectrometry and gas chromatography-mass spectrometry were used to identify medicinal drugs, drugs of abuse, pesticides, poison gases, etc. ResultsAFS received a total of 17,758 cases in 2021, of which 314 cases underwent autopsy. The main cause of death was sudden death, and the manner of death was mainly accident. Among 13,744 drug abuse cases, the number of positive cases was 1721, with a positive rate of 12.5%, and synthetic cannabinoids were the most frequently detected substances. In 3640 traffic cases, 85.3% of drivers were suspected of drunk driving. In 103 poisoning cases, hydrogen sulfide poisoning and pesticide suicide account for a large proportion. In drug-facilitated crimes, zolpidem was the most frequently tested component. In 55 case of dog poisonings, the main poisons were cyanides and succinylcholine, and the main poisoning tools were poisonous baits and poisonous syringe darts. ConclusionsThis study profiles the toxicological characteristics of forensic toxicological cases conducted at the AFS in 2021 and provides a scientific basis for poisoning cases and drug abuse prevention.

Liver Transplantation After Organ Donation Due to Hydrogen Sulfide Intoxication: Report of the First Case.

The discrepancy of patients on the waiting list and the availability of organs suitable for transplantation continues to represent a relevant problem in transplantation medicine. Regarding liver transplantation, the increasing use of organs from donors with so-called extended criteria meanwhile has become daily practice in many countries.1 Consequently, every potential donor reported is carefully evaluated for suitability for organ donation. When a liver from a young brain-dead donor after hydrogen sulfide (H2S) intoxication was offered for a high-urgency listed patient, research of the literature did not provide any help for decision making in organ allocation. Herewith, we want to share our experience following the successful use of this donor liver for transplantation. A 60-y-old female patient with acute liver failure caused by an autoimmune hepatitis was transferred to our center and eventually listed for high-urgency liver transplantation following biopsy-proven diagnosis and rapid worsening of the clinical condition despite thorough intensive medical treatment (see Figure 1). Within 5 h after approval of high-urgency status, we were offered a liver from a 19-y-old female brain-dead donor following H2S intoxication in suicidal intent. Apart from depression, the donor was in excellent general condition before intoxication and had no other known illnesses. Despite recently promoted organ protective effects in experimental studies,2 inhalation of H2S in higher concentrations is highly toxic and eventually led to cardiac arrest in this patient.3 Following a short period of resuscitation, the donor was admitted to an intensive care unit and eventually diagnosed brain dead. Within 24 h, severe lung edema and subsequently respiratory failure developed as signs of multiorgan failure. Regarding the liver, apart from an initial peak of transaminases (peak AST and ALT levels of 357 and 438 U/L, respectively), the laboratory findings were all unremarkable. Because of the severe condition of our recipient with severe hepatic encephalopathy, we thus accepted the organ after intense interdisciplinary discussion despite the lack of any data on successful use of organs for transplant under these conditions. Upon arrival of the organ at our center, histological work-up of the liver by frozen section was performed despite excellent macroscopic appearance, which did not reveal any signs of acute liver injury or chronic alterations‚ such as steatosis or fibrosis (see Figure 2). Subsequent liver transplantation was completely uneventful. The patient’s clinical condition improved rapidly, with discharge at day 15 after transplantation (see Figure 1). During follow-up of 6 mo, no irregularities were observed, with excellent graft function and medical condition of the recipient at last visit. In conclusion, to our knowledge‚ this is the first report of a liver transplant from a brain-dead donor after hydrogen sulfide intoxication. Based on this single-case experience, potential donors after hydrogen sulfide intoxication should be carefully evaluated and considered for organ donation. Particularly evaluation of potential grafts applying normothermic machine perfusion might represent another valuable option in case of less urgent conditions of the recipients.4FIGURE 1.: Course of laboratory parameters (AST, ALT [both U/L], bilirubin [µmol/L], and INR) of the recipient before and after LTx, with time points of liver biopsy, PE and steroid therapy‚ and day of transplantation indicated by gray bars. ALT, alanine aminotransferase; AST, aspartate aminotransferase; INR, international normalized ratio; LTx, liver transplantation; PE, plasmapheresis.FIGURE 2.: Histopathology of liver wedge biopsy: hematoxylin and eosin staining shows no steatosis, fibrosis, or cirrhosis ([A] ×40 magnification and [B] ×100 magnification), and Elastica van Gieson staining highlights absence of fibrosis within the liver parenchyma ([C] ×40 magnification and [D] ×100 magnification).

Two-Screen Virtual Board Game Didactic for Teaching Wilderness and Environmental Medicine Topics to Emergency Medicine Residents.

This game is appropriate for medical students, interns, junior and senior residents. The COVID-19 pandemic has forced a transition from in-person to virtual learning, and educators must innovate and adapt to keep learners engaged. One way to achieve this is through gamification.1 The authors employed a novel approach to gamification of virtual learning which engaged not only learners' computers but also their mobile phones. Learners worked in teams communicating by text message to answer ABEM board-style questions and occupy sites on the virtual board. By the end of this didactic, the learner will:1. Describe the basics of the presentation of each topic listed above2. Recall the basics of management of each topic listed above3. Improve learners' preparedness for the Emergency Medicine Inservice Exam and Written Board Examination. Wilderness and environmental medicine topics were selected from the list of topics covered on the ABEM boards. Questions were then written by the authors teaching these concepts. Learners were surveyed immediately following the session using an evaluation tool containing both Likert-scale questions on quality and applicability as well as open-ended questions on strengths and areas for improvement. The response rate to this survey was 100%. Feedback was overwhelmingly positive, with 19/20 respondents rating the sessions 5/5 for effectiveness and value of teaching compared with other sessions, and 1/20 rating the session 4/5. Nineteen out of twenty respondents rated the content as "highly relevant"; 1/20 rated it as "mostly relevant." Nineteen out of twenty respondents rated the session 5/5 for being engaging and holding their attention; 1/20 rated it as somewhat engaging. Learners rated the session as highly relevant and engaging. We hypothesize that by engaging two screens and forcing learners to work together by text message, we were able to turn what would normally be a distraction (texting co-residents during resident conference) into a tool for learning. Electrical injury, lightning strike, thermal burns, inhalational injury, chemical burns, acute radiation syndrome, snake bites, scorpion envenomation, stingray envenomation, jellyfish stings, black widow spider bites, mammalian bites, rabies, murine typhus, bear encounters, decompression sickness, arterial gas embolism, drowning, dehydration, heat stroke, exercise-associated hyponatremia, frostbite, hypothermia, CO poisoning, hydrogen sulfide poisoning, giardia.

Diagnosis Model of Hydrogen Sulfide Poisoning Based on Support Vector Machine

Introduction: Hydrogen sulfide (H2S) is a lethal environmental and industrial poison. The mortality rate of occupational acute H2S poisoning reported in China is 23.1% ~ 50%. Due to the huge amount of information on metabolomics changes after body poisoning, it is important to use intelligent algorithms to mine multivariate interactions. Methods: This paper first uses GC-MS metabolomics to detect changes in the urine components of the poisoned group and control rats to form a metabolic dataset, and then uses the SVM classification algorithm in machine learning to train the hydrogen sulfide poisoning training dataset to obtain a classification recognition model. A batch of rats (n = 15) was randomly selected and exposed to 20 ppm H2S gas for 40 days (twice morning and evening, 1 hour each exposure) to prepare a chronic H2S rat poisoning model. The other rats (n = 15) were exposed to the same volume of air and 0 ppm hydrogen sulfide gas as the control group. The treated urine samples were tested using a GC-MS. Results: The method locates the optimal parameters of SVM, which improves the accuracy of SVM classification to 100%. This paper uses the information to gain an attribute evaluation method to screen out the top 6 biomarkers that contribute to the predicted category (Glycerol, -Hydroxybutyric acid, arabinofuranose, Pentitol, L-Tyrosine, L-Proline). Conclusion: The SVM diagnostic model of hydrogen sulfide poisoning constructed in this work has training time and prediction accuracy; it has achieved excellent results and provided an intelligent decision-making method for the diagnosis of hydrogen sulfide poisoning.

Unified Metallic Catalyst Aging Strategy and Implications for Water Treatment.

Heterogeneous catalysis holds great promise for oxidizing or reducing a range of pollutants in water. A well-recognized, but understudied, barrier to implement catalytic treatment centers around fouling or aging over time of the catalyst surfaces. To better understand how to study catalyst fouling or aging, we selected a representative bimetallic catalyst (Pd-In supported on Al2O3), which holds promise to reduce nitrate to innocuous nitrogen gas byproducts upon hydrogen addition, and six model solutions (deionized water, sodium hypochlorite, sodium borohydride, acetic acid, sodium sulfide, and tap water). Our novel aging experimental apparatus permitted single passage of each model solution, separately, through a small packed-bed reactor containing replicate bimetallic catalyst "beds" that could be sacrificed weekly for off-line characterization to quantify impacts of fouling or aging. The composition of the model solutions led to the following gradual changes in surface composition, morphology, or catalytic reactivity: (i) formation of passivating species, (ii) decreased catalytic sites due to metal leaching under acid conditions or sulfide poisoning, (iii) dissolution and/or transformation of indium, (iv) formation of new catalytic sites by the introduction of an additional metallic element, and (v) oxidative etching. The model solution water chemistry captured a wide range of conditions likely to be encountered in potable or industrial water treatment. Aging-induced changes altered catalytic activity and provided insights into potential strategies to improve long-term catalyst operations for water treatment.

A Sulfonyl Azide-Based Sulfide Scavenger Rescues Mice from Lethal Hydrogen Sulfide Intoxication.

Exposure to hydrogen sulfide (H2S) can cause neurotoxicity and cardiopulmonary arrest. Resuscitating victims of sulfide intoxication is extremely difficult, and survivors often exhibit persistent neurological deficits. However, no specific antidote is available for sulfide intoxication. The objective of this study was to examine whether administration of a sulfonyl azide-based sulfide-specific scavenger, SS20, would rescue mice in models of H2S intoxication: ongoing exposure and post-cardiopulmonary arrest. In the ongoing exposure model, SS20 (1250 µmol/kg) or vehicle was administered to awake CD-1 mice intraperitoneally at 10 min after breathing 790 ppm of H2S followed by another 30 min of H2S inhalation. Effects of SS20 on survival were assessed. In the post-cardiopulmonary arrest model, cardiopulmonary arrest was induced by an intraperitoneal administration of sodium sulfide nonahydrate (125 mg/kg) in anesthetized mice. After 1 min of cardiopulmonary arrest, mice were resuscitated with intravenous administration of SS20 (250 µmol/kg) or vehicle. Effects of SS20 on survival, neurological outcomes, and plasma H2S levels were evaluated. Administration of SS20 during ongoing H2S inhalation improved 24-h survival (6/6 [100%] in SS20 vs 1/6 [17%] in vehicle; p = .0043). Post-arrest administration of SS20 improved 7-day survival (4/10 [40%] in SS20 vs 0/10 [0%] in vehicle; p = .0038) and neurological outcomes after resuscitation. SS20 decreased plasma H2S levels to pre-arrest baseline immediately after reperfusion and shortened the time to return of spontaneous circulation and respiration. These results suggest that SS20 is an effective antidote against lethal H2S intoxication, even when administered after cardiopulmonary arrest.

Permian–Triassic mass extinction pulses driven by major marine carbon cycle perturbations

The Permian/Triassic boundary approximately 251.9 million years ago marked the most severe environmental crisis identified in the geological record, which dictated the onwards course for the evolution of life. Magmatism from Siberian Traps is thought to have played an important role, but the causational trigger and its feedbacks are yet to be fully understood. Here we present a new boron-isotope-derived seawater pH record from fossil brachiopod shells deposited on the Tethys shelf that demonstrates a substantial decline in seawater pH coeval with the onset of the mass extinction in the latest Permian. Combined with carbon isotope data, our results are integrated in a geochemical model that resolves the carbon cycle dynamics as well as the ocean redox conditions and nitrogen isotope turnover. We find that the initial ocean acidification was intimately linked to a large pulse of carbon degassing from the Siberian sill intrusions. We unravel the consequences of the greenhouse effect on the marine environment, and show how elevated sea surface temperatures, export production and nutrient input driven by increased rates of chemical weathering gave rise to widespread deoxygenation and sporadic sulfide poisoning of the oceans in the earliest Triassic. Our findings enable us to assemble a consistent biogeochemical reconstruction of the mechanisms that resulted in the largest Phanerozoic mass extinction. The end-Permian mass extinction was linked with ocean acidification due to carbon degassing associated with Siberian Trap emplacement, according to boron isotopes from fossil shells and reconstruction of the carbon cycle.

Sample preparation method with ultrafiltration for whole blood thiosulfate measurement.

Quantitative analysis of thiosulfate is useful for diagnosing hydrogen sulfide poisoning. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) enables more rapid and sensitive measurements than previous methodologies. As simple measurements of blood thiosulfate concentration are affected by the blood matrix, blood is used as the solvent to prepare the standard solution for calibration curve generation. Thus, a large amount of blood devoid of thiosulfate is required. We developed a preparation method by incorporating an ultrafiltration step to overcome this limitation and generate a calibration curve using a standard solution prepared with pure water. We used this improved method to investigate the stability of thiosulfate in refrigerated samples. To compare the effects of refrigeration, blood samples were prepared using the following two methods: one sample was treated with a 50-kDa exclusion ultrafiltration membrane and the other was not treated. The samples were stored at 4°C, and then measured at 0, 3, 6, 24, 48, and 96h. The incorporation of the ultrafiltration step in the measurement procedure enabled the quantification of thiosulfate, by plotting a calibration curve using a standard of pure water; it did not require a blood standard. Additionally, the reduction in whole blood thiosulfate concentration was within 10% during 2days of refrigeration. Thus, the need for a large amount of blood to prepare the standard solution was resolved by the ultrafiltration step in test sample preparation. This method is useful to measure thiosulfate concentration and is not hindered by sample refrigeration for a few days.

Occupational Health Risks in Logging and Wood Processing in the Russian Arctic

Introduction: Despite the extreme environmental conditions, an extensive economic activity based on the extraction and processing of natural resources is ongoing in the Russian Arctic. The objective of the study was to investigate occupational health risk factors for workers engaged in lumbering and wood processing in the Russian Arctic. Materials and methods: The socio-hygienic monitoring data on working conditions and occupational diseases in the population of the Russian Arctic zone in 2007–2018 were analyzed. Results: In 2007–2018, 222 occupational diseases were identified including 180 cases in wood processing workers, 25 cases in loggers, and 17 cases in people employed in the production of pulp, paper, and paper products. The development of occupational pathology was mainly induced by the increased severity of labor (70.3%) related to imperfection of technological processes (76.1%) and structural limitations of equipment (22.1%). Musculoskeletal disorders prevailed with myofibrosis of the forearm ranking first. All health disorders were chronic with the exception of two cases of acute hydrogen sulfide poisoning. The largest number of diseases (n=117) was diagnosed in 2007-2010 while the smallest (n=14) in 2015–2018 (an 8.36-fold decrease). The risk of developing occupational pathology in 2007 was higher than in 2018, the relative risk being 9.60 (CI: 2.30–40.1; p=0.00014). Over a half (129 or 58.1%) of occupational diseases were diagnosed as a result of self-seeking of medical care while 93 (41.9%) cases were revealed in the course of planned medical examinations. Conclusions: Efficient prevention of occupational diseases in the industry can only be achieved by improving labor conditions and, above all, reducing the severity of labor processes. Reliability of official data on the number of incident cases of occupational diseases among workers involved in timber harvesting and processing in the Arctic raises doubts.

Methylene blue-based 7-nitro-1,2,3-benzoxadiazole NIR fluorescent probe triggered by H2S

A new Methylene blue–based 7-nitro-1,2,3-benzoxadiazole NIR fluorescent probe 3, 7-bis-dimethylamino-10-(7-nitrobenzo[c][1,2,5]oxadiazol-4-yl)-10H-phenothiazine (leuco-MB-NBD) was designed and synthesized. Leuco-MB-NBD showed high sensitivity and selectivity for H2S as a fluorescent probe in C2H5OH-PBS (9:1, v/v, pH = 7.4) solution, this fluorescent assay showed a linear range of 0–50.0 μM and a LOD (limit of detection) of 0.43 μM. Moreover, the probe leuco-MB-NBD has lower toxicity at low concentrations to HCT-116 cells and can be used for cell imaging. Additionally, Leuco-MB-NBD is triggered by hydrogen sulfide to generate methylene blue, methylene blue which has potential rescuing effects on the mitochondrial activity can act as an antidote against sulfide intoxication.

From probe to antidote

Researchers have found a surprising use for a database of fluorescent probes: searching for antidotes to hydrogen sulfide (H2S) poisoning. Washington State University chemist Ming Xian and a team of undergraduate helpers initially built the searchable database to help biologists sort through the multitude of availble H2S fluorophores. When he found out that H2S is a potential chemical weapon, he found a new use for the data: searching for compounds that might be used to treat H2S poisoning by scavening it from the body (Angew. Chem., Int. Ed. 2019, DOI: 10.1002/anie.201905580). “I didn’t plan to do this,” Xian admits. “If we didn’t have this database, probably I would never have thought about designing scavengers.” H2S is a simple molecule with a surprising variety of roles. In the body it relaxes smooth muscle and causes blood vessels to dilate. It also plays a role in diseases like cancer and diabetes. But