Acute hydrogen sulfide poisoning in a dairy farmer

A 'Frugal' EGFET Sensor for Waterborne H2S

Hydrogen sulphide (H2S) is a toxic gas soluble in water, H2Saq, as a weak acid. Since H2Saq usually originates from the decomposition of faecal matter, its presence also indicates sewage dumping and possible parallel waterborne pathogens associated with sewage. We here present a low footprint ('frugal') H2Saq sensor as an accessible resource for water quality monitoring. As a sensing mechanism, we find the chemical affinity of thiols to gold (Au) translates to H2Saq. When an Au electrode is used as a control gate (CG) or floating gate (FG) electrode in the electric double layer (EDL) pool of an extended gate field effect transistor (EGFET) sensor, EGFET transfer characteristics shift along the CG voltage axis in response to H2Saq. We rationalise this by the interface potential from the adsorption of polar H2S molecules to the electrode. The sign of the shift changes between Au CG and Au FG, and cancels when both electrodes are Au. The sensor is selective for H2Saq over the components of urine, nor does urine suppress the sensor's ability to detect H2Saq. Electrodes can be recovered for repeated use by washing in 1M HCl. Quantitatively, CG voltage shift is fitted by a Langmuir-Freundlich (LF) model, supporting dipole adsorption over an ionic (Nernstian) response mechanism. We find a limit-of-detection of 14.9 nM, 100 times below potability.

A comprehensive review of treatments for hydrogen sulfide poisoning: past, present, and future

Hydrogen sulfide (H₂S) poisoning remains a significant source of occupational fatalities and is the second most common cause of toxic gas-induced deaths. It is a rapidly metabolized systemic toxicant targeting the mitochondria, among other organelles. Intoxication is mostly acute, but chronic or in-between exposure scenarios also occur. Some genetic defects in H₂S metabolism lead to lethal chronic H₂S poisoning. In acute exposures, the neural, respiratory, and cardiovascular systems are the primary target organs resulting in respiratory distress, convulsions, hypotension, and cardiac irregularities. Some survivors of acute poisoning develop long-term sequelae, particularly in the central nervous system. Currently, treatment for H₂S poisoning is primarily supportive care as there are no FDA-approved drugs. Besides hyperbaric oxygen treatment, drugs in current use for the management of H₂S poisoning are controversial. Novel potential drugs are under pre-clinical research development, most of which target binding the H₂S. However, there is an acute need to discover new drugs to prevent and treat H₂S poisoning, including reducing mortality and morbidity, preventing sequalae from acute exposures, and for treating cumulative pathology from chronic exposures. In this paper, we perform a comprehensive review of H₂S poisoning including perspectives on past, present, and future.

Hydrogen sulfide poisoning in forensic pathology and toxicology: mechanism and metabolites quantification analysis

Historically, hydrogen sulfide (H₂S) poisoning has extremely high and irreparable mortality. Currently, the identification of H₂S poisoning needs to combine with the case scene analysis in forensic medicine. The anatomy of the deceased seldom had obvious features. There are also a few reports about H₂S poisoning in detail. As a result, we give a comprehensive analysis of the related knowledge on the forensic aspect of H₂S poisoning. Furthermore, we provide the analytical methods of H₂S and its metabolite-which may assist in H₂S poisoning identification.

Inhalants

Toxic inhalants include various xenobiotics. Irritants cause upper and lower respiratory tract injuries. Highly water-soluble agents injure the upper respiratory tract, while low water-soluble inhalants injure the lower track. Asphyxiants are divided into simple asphyxiants and chemical asphyxiants. Simple asphyxiants displace oxygen, causing hypoxia, while chemical asphyxiants also impair the body's ability to use oxygen. Cyanide is a classic chemical asphyxiant. Treatment includes hydroxocobalamin. Electronic cigarette or vaping use-associated lung injury (EVALI) is a relatively new illness. Patients present with respiratory symptoms and gastrointestinal distress. EVALI appears to be associated with vaping cannabinoids. Treatment is supportive and may include steroids.

Effect of ractopamine hydrochloride on environmental gas emissions, growth performance, and carcass characteristics in feedlot steers

With a growing global population and increased environmental concerns around animal agriculture, it is essential to humanely maximize animal performance and reduce environmental emissions. This study aims to determine the efficacy of feeding ractopamine hydrochloride (RAC), an orally active, β 1-adrenergic agonist (β1AA), to feedlot steers in the last 42 d of finishing to reduce ammonia (NH3) emissions and improve animal performance. A randomized complete block design was used to allocate 112 Angus and crossbred Angus steers (initial body weight [BW] = 566.0 ± 10.4 kg) to 8 cattle pen enclosures. Pens (n = 4 per treatment, 14 steers per pen, and 56 steers per treatment) were randomly assigned to one of two treatments: 1) CON; finishing ration containing no RAC, 2) RAC; finishing ration containing 27.3 g/907 kg dry matter (DM) basis RAC. Steers were weighed on day -1 and 0 before treatment and day 14, 28, and 42 during treatment. Treatment rations were mixed and delivered daily by masked personnel. Measured emissions included NH3, nitrous oxide (N2O), methane (CH4), hydrogen sulfide (H2S), and carbon dioxide (CO2). The primary response variables assessed were emissions standardized by live weight (LW) and hot carcass weight (HCW). Steers were harvested on day 43 and carcass data were collected on day 43 and 44. Steers fed RAC reduced NH3 emissions by 17.21% from day 0 to 28 (P = 0.032) and tended to reduce NH3 from day 0 to 42 by 11.07% (P = 0.070) vs. CON. When standardized for LW, NH3 was reduced by 23.88% from day 0 to 14 (P = 0.018), 17.80% from day 0 to 28 (P = 0.006), and 12.50% for day 0 to 42 (P = 0.027) in steers fed RAC vs. CON. Steers fed RAC had 14.05% (P = 0.013) lower cumulative NH3 emissions when standardized by HCW vs. CON. Feeding RAC to Steers reduced H2S by 29.49% from day 0 to 14 (P = 0.009) and tended to reduce H2S over day 0 to 28 by 11.14% (P = 0.086) vs. CON. When H2S emissions were standardized for LW, RAC fed steers had a 28.81% reduction from day 0 to 14 (P = 0.008) vs. CON. From day 0 to 42 the RAC fed steers tended to have a 0.24 kg/d greater average daily gain (ADG) (P = 0.066) and tended to eat 4.27% less (P = 0.069) on a DM basis vs. CON. The RAC fed steers had a 19.95% greater gain to feed ratio (G:F) compared to CON (P = 0.012). Steers fed RAC had an average of 12.52 kg greater HCW (P = 0.006) and an increase of 1.93 percentage units in dressing percent (DP) (P = 0.004) vs. CON. Ractopamine is an effective medicated feed additive for reducing NH3 and improving end product performance through HCW yields.

Chromogenic detection of hydrogen sulfide using squarylium-based chemosensors

Squarylium-based colorimetric hydrogen sulfide (H₂S) chemosensors (SQ1, SQ2, and SQ3) were developed, and their detection properties were systematically characterized. SQ1 exhibited rapid and high resolution H₂S sensing properties through significant color changes detectable by naked-eye with limit of detection as low as 7.2 ppb. SQ1 also showed excellent selectivity for H₂S detection over other relevant anions and nucleophiles. Sensing mechanisms of SQ1 were investigated based on spectroscopic and ¹H NMR analyses with quantum calculations. Furthermore, SQ1 showed an efficient response to H2S under versatile conditions in the solution, solid, and dyed fabric states, which suggests applicability of SQ1 to simple, low-cost, and practical H₂S sensors.

A Review of Potential Public Health Impacts Associated With the Global Dairy Sector

Strong demand for dairy products has led to a global increase in dairy production. In many parts of the world, dairy systems are undergoing rapid intensification. While increased production may contribute to food security, higher dairy stocking rates in some regions have resulted in increased pressure on natural resources with the potential to affect public health and wellbeing. The aim of this review was to identify and describe the potential health harms and benefits associated with dairy production and consumption. Electronic databases Medline, Embase, Scopus, Web of Science, PubMed, and Google Scholar were searched for published literature that investigated human health impacts of dairy production and consumption. Occupational hazards, environmental health impacts, ecosystem health impacts, foodborne hazards, and diet-related chronic diseases were identified as potential public health hazards. Some impacts, notably climate change, extend beyond directly exposed populations. Dairy production and consumption are also associated with important health benefits through the provision of nutrients and economic opportunities. As the global dairy sector increases production, exposure to a range of hazards must be weighed with these benefits. The review of impacts presented here can provide an input into decision making about optimal levels of dairy production and consumption, local land use, and identification and management of specific hazards from this sector. Future research should consider multiple exposure routes, socioeconomic implications, and environmental factors, particularly in regions heavily dependent on dairy farming.

Hydrogen Sulfide Gas Exposure Induces Necroptosis and Promotes Inflammation through the MAPK/NF-κB Pathway in Broiler Spleen

Hydrogen sulfide (H2S) is one of the main pollutants in the atmosphere, which is a serious threat to human health. The decomposition of sulfur-containing organics in chicken houses could produce a large amount of H2S, thereby damaging poultry health. In this study, one-day-old broilers were selected and exposed to 4 or 20 ppm of H2S gas (0-3 weeks: 4 ± 0.5 ppm, 4-6 weeks: 20 ± 0.5 ppm). The spleen samples were collected immediately after the chickens were euthanized at 2, 4, and 6 weeks. The histopathological and ultrastructural observations showed obvious necrosis characteristics of H2S-exposed spleens. H2S exposure suppressed GSH, CAT, T-AOC, and SOD activities; increased NO, H2O2, and MDA content and iNOS activity; and induced oxidative stress. ATPase activities and the expressions of energy metabolism-related genes were significantly decreased. Also, the expressions of related necroptosis (RIPK1, RIPK3, MLKL, TAK1, TAB2, and TAB3) were significantly increased, and the MAPK pathway was activated. Besides, H2S exposure activated the NF-κB classical pathway and induced TNF-α and IL-1β release. Taken together, we conclude that H2S exposure induces oxidative stress and energy metabolism dysfunction; evokes necroptosis; activates the MAPK pathway, eventually triggering the NF-κB pathway; and promotes inflammatory response in chicken spleens.

Revisiting the systemic lipopolysaccharide mediated neuroinflammation: Appraising the effect of l-cysteine mediated hydrogen sulphide on it

The present research was ventured to examine the effect of l-cysteine on neuro-inflammation persuaded by peripheral lipopolysaccharides (LPS, 125 μg/kg, i.p.) administration. No behavioral, biochemical, and inflammatory abnormality was perceived in the brain tissues of experimental animals after LPS administration. l-cysteine precipitated marginal symptoms of toxicity in the brain tissue. Similar pattern of wholesome effect of LPS were perceived when evaluated through the brain tissue fatty acid profile, histopathologically and NF-ĸBP65 protein expression. LPS was unsuccessful to alter the levels of hydrogen sulphide (H₂S), cyclooxygenase (COX) and lipoxygenase (LOX) enzyme in brain tissue. LPS afforded significant peripheral toxicity, when figured out through inflammatory markers (COX, LOX), gaseous signaling molecules nitric oxide (NO), H₂S, liver toxicity (SGOT, SGPT), and inflammatory transcription factor (NF-ĸBP65) and l-cysteine also provided a momentous protection against the same as well. The study inculcated two major finding, firstly LPS (i.p.) cannot impart inflammatory changes to brain and secondly, l-cysteine can afford peripheral protection against deleterious effect of LPS (i.p.)

Midazolam Efficacy Against Acute Hydrogen Sulfide-Induced Mortality and Neurotoxicity

Hydrogen sulfide (H₂S) is a colorless, highly neurotoxic gas. It is not only an occupational and environmental hazard but also of concern to the Department of Homeland Security for potential nefarious use. Acute high-dose H₂S exposure causes death, while survivors may develop neurological sequelae. Currently, there is no suitable antidote for treatment of acute H₂S-induced neurotoxicity. Midazolam (MDZ), an anti-convulsant drug recommended for treatment of nerve agent intoxications, could also be of value in treating acute H₂S intoxication. In this study, we tested the hypothesis that MDZ is effective in preventing/treating acute H₂S-induced neurotoxicity. This proof-of-concept study had two objectives: to determine whether MDZ prevents/reduces H₂S-induced mortality and to test whether MDZ prevents H₂S-induced neurological sequelae. MDZ (4 mg/kg) was administered IM in mice, 5 min pre-exposure to a high concentration of H₂S at 1000 ppm or 12 min post-exposure to 1000 ppm H₂S followed by 30 min of continuous exposure. A separate experiment tested whether MDZ pre-treatment prevented neurological sequelae. Endpoints monitored included assessment of clinical signs, mortality, behavioral changes, and brain histopathological changes. MDZ significantly reduced H₂S-induced lethality, seizures, knockdown, and behavioral deficits (p < 0.01). MDZ also significantly prevented H₂S-induced neurological sequelae, including weight loss, behavior deficits, neuroinflammation, and histopathologic lesions (p < 0.01). Overall, our findings show that MDZ is a promising drug for reducing H₂S-induced acute mortality, neurotoxicity, and neurological sequelae.

Cobinamide is effective for treatment of hydrogen sulfide-induced neurological sequelae in a mouse model

Hydrogen sulfide (H2 S) is a highly neurotoxic gas. Acute exposure can lead to neurological sequelae among survivors. A drug for treating neurological sequelae in survivors of acute H2 S intoxication is needed. Using a novel mouse model we evaluated the efficacy of cobinamide (Cob) for increasing survival of, and reducing neurological sequalae in, mice exposed to sublethal doses of H2 S. There were two objectives: (1) to determine the dose-response efficacy of Cob and (2) to determine the effective therapeutic time window of Cob. To explore objective 1, mice were injected intramuscularly with Cob at 0, 50, or 100 mg/kg at 2 min after H2 S exposure. For objective 2, mice were injected intramuscularly with 100 mg/kg Cob at 2, 15, and 30 min after H2 S exposure. For both objectives, mice were exposed to 765 ppm of H2 S gas. Cob significantly reduced H2 S-induced lethality in a dose-dependent manner (P < 0.05). Cob-treated mice exhibited significantly fewer seizures and knockdowns compared with the H2 S-exposed group. Cob also reversed H2 S-induced weight loss, behavioral deficits, neurochemical changes, cytochrome c oxidase enzyme inhibition, and neurodegeneration in a dose- and time-dependent manner (P < 0.01). Overall, these findings show that Cob increases survival and is neuroprotective in a mouse model of H2 S-induced neurological sequelae.

Characterizing a mouse model for evaluation of countermeasures against hydrogen sulfide-induced neurotoxicity and neurological sequelae

Hydrogen sulfide (H₂ S) is a highly neurotoxic gas. It is the second most common cause of gas-induced deaths. Beyond mortality, surviving victims of acute exposure may suffer long-term neurological sequelae. There is a need to develop countermeasures against H₂ S poisoning. However, no translational animal model of H₂ S-induced neurological sequelae exists. Here, we describe a novel mouse model of H₂ S-induced neurotoxicity for translational research. In paradigm I, C57/BL6 mice were exposed to 765 ppm H₂ S for 40 min on day 1, followed by 15-min daily exposures for periods ranging from 1 to 6 days. In paradigm II, mice were exposed once to 1000 ppm H₂ S for 60 minutes. Mice were assessed for behavioral, neurochemical, biochemical, and histopathological changes. H₂ S intoxication caused seizures, dyspnea, respiratory depression, knockdowns, and death. H₂ S-exposed mice showed significant impairment in locomotor and coordinated motor movement activity compared with controls. Histopathology revealed neurodegenerative lesions in the collicular, thalamic, and cortical brain regions. H₂ S significantly increased dopamine and serotonin concentration in several brain regions and caused time-dependent decreases in GABA and glutamate concentrations. Furthermore, H₂ S significantly suppressed cytochrome c oxidase activity and caused significant loss in body weight. Overall, male mice were more sensitive than females. This novel translational mouse model of H₂ S-induced neurotoxicity is reliable, reproducible, and recapitulates acute H₂ S poisoning in humans.

A gas chromatography-mass spectrometry based study on urine metabolomics in rats chronically poisoned with hydrogen sulfide

Gas chromatography-mass spectrometry (GS-MS) in combination with multivariate statistical analysis was applied to explore the metabolic variability in urine of chronically hydrogen sulfide- (H2S-) poisoned rats relative to control ones. The changes in endogenous metabolites were studied by partial least squares-discriminate analysis (PLS-DA) and independent-samples t-test. The metabolic patterns of H2S-poisoned group are separated from the control, suggesting that the metabolic profiles of H2S-poisoned rats were markedly different from the controls. Moreover, compared to the control group, the level of alanine, d-ribose, tetradecanoic acid, L-aspartic acid, pentanedioic acid, cholesterol, acetate, and oleic acid in rat urine of the poisoning group decreased, while the level of glycine, d-mannose, arabinofuranose, and propanoic acid increased. These metabolites are related to amino acid metabolism as well as energy and lipid metabolism in vivo. Studying metabolomics using GC-MS allows for a comprehensive overview of the metabolism of the living body. This technique can be employed to decipher the mechanism of chronic H2S poisoning, thus promoting the use of metabolomics in clinical toxicology.

Hydrogen sulfide intoxication

Hydrogen sulfide (H2S) is a hazard primarily in the oil and gas industry, agriculture, sewage and animal waste handling, construction (asphalt operations and disturbing marshy terrain), and other settings where organic material decomposes under reducing conditions, and in geothermal operations. It is an insoluble gas, heavier than air, with a very low odor threshold and high toxicity, driven by concentration more than duration of exposure. Toxicity presents in a unique, reliable, and characteristic toxidrome consisting, in ascending order of exposure, of mucosal irritation, especially of the eye ("gas eye"), olfactory paralysis (not to be confused with olfactory fatigue), sudden but reversible loss of consciousness ("knockdown"), pulmonary edema (with an unusually favorable prognosis), and death (probably with apnea contributing). The risk of chronic neurcognitive changes is controversial, with the best evidence at high exposure levels and after knockdowns, which are frequently accompanied by head injury or oxygen deprivation. Treatment cannot be initiated promptly in the prehospital phase, and currently rests primarily on supportive care, hyperbaric oxygen, and nitrite administration. The mechanism of action for sublethal neurotoxicity and knockdown is clearly not inhibition of cytochrome oxidase c, as generally assumed, although this may play a role in overwhelming exposures. High levels of endogenous sulfide are found in the brain, presumably relating to the function of hydrogen sulfide as a gaseous neurotransmitter and immunomodulator. Prevention requires control of exposure and rigorous training to stop doomed rescue attempts attempted without self-contained breathing apparatus, especially in confined spaces, and in sudden release in the oil and gas sector, which result in multiple avoidable deaths.

Hydrogen sulfide measurement by headspace-gas chromatography-mass spectrometry (HS-GC-MS): application to gaseous samples and gas dissolved in muscle

The aim of our study was to present a new headspace-gas chromatography-mass spectrometry (HS-GC-MS) method applicable to the routine determination of hydrogen sulfide (H(2)S) concentrations in biological and gaseous samples. The primary analytical drawback of the GC/MS methods for H(2)S measurement discussed in the literature was the absence of a specific H(2)S internal standard required to perform quantification. Although a deuterated hydrogen sulfide (D(2)S) standard is currently available, this standard is not often used because this standard is expensive and is only available in the gas phase. As an alternative approach, D(2)S can be generated in situ by reacting deuterated chloride with sodium sulfide; however, this technique can lead to low recovery yield and potential isotopic fractionation. Therefore, N(2)O was chosen for use as an internal standard. This method allows precise measurements of H(2)S concentrations in biological and gaseous samples. Therefore, a full validation using accuracy profile based on the β-expectation tolerance interval is presented. Finally, this method was applied to quantify H(2)S in an actual case of H(2)S fatal intoxication.

Carbamodithioate-based dual functional fluorescent probe for Hg(2+) and S(2-)

Carbamodithioate-based compound T1 was designed and synthesized as a dual-functional probe for Hg(2+) ions and S(2-) anions. The underlying signaling mechanism was intramolecular charge transfer (ICT). It could serve as a direct probe towards Hg(2+) ions through "on-off" fluorescence changes and an indirect probe towards S(2-) anions through "on-off-on" fluorescence changes.

A multicenter retrospective survey on a suicide trend using hydrogen sulfide in Japan

CONTEXT

In Japan, suicide by inhaling hydrogen sulfide (H2S) by mixing commercial products escalated into a nationwide trend in April 2008.

OBJECTIVE

We conducted a multicenter retrospective survey on the demographics, clinical features, treatments, and outcomes of patients exposed to H2S suicide attempts.

MATERIALS AND METHODS

Subjects included patients transported to emergency facilities in Japan from January 2005 to December 2011 following H2S suicide attempts. Among 277 facilities to which a letter requesting data collection was sent, questionnaires were sent to and filled out by the 47 (18%) facilities that agreed to provide data. Questionnaires were collected and data were extracted at Kitasato University.

RESULTS

A total of 156 patients were included in this survey. Patients involved in an H2S suicide attempt increased from 1 in 2007 to 51 in 2008, and gradually decreased from 44 in 2009 to 37 in 2010 and 23 in 2011. Ninety-two patients attempted H2S suicide (primary exposure group), and 64 were secondarily affected by the suicide attempt (secondary exposure group). Patients in the primary exposure group were young (mean, 30.3 years (10.9)), and male patients (n = 62) were approximately two times more likely to attempt H2S suicide than females (n = 30). Forty-eight patients in cardiopulmonary arrest at the scene did not survive. Five non-cardiopulmonary arrest patients died, and five patients who presented with a Glasgow coma scale (GCS) < 8 and lactic acidosis had neurological or cardiac signs or symptoms at discharge. Antidote therapy was performed on 26 of the primary group patients, but with poor outcomes. None of the secondary group patients were in cardiopulmonary arrest at the scene, five received antidotal therapy after arriving at the hospital, and all completely recovered from H2S exposure.

DISCUSSION AND CONCLUSION

Mortality (58%) among patients who attempted H2S suicide was very high, likely resulting from inhaling high concentrations of H2S after mixing commercial products in a sealed and confined space.

[Severe hydrogen sulfide intoxication: a pediatric case of survival]

We report a paediatric case of survival following severe hydrogen sulfide (H2S) gas intoxication. A 13-year-old boy was found submerged to the neck in a manure tank. He was hypothermic, unresponsive with bilateral mydriasis, and had poor oxygen saturation. After intubation, he was transferred to the paediatric intensive care unit of a tertiary care children's hospital. He developed acute respiratory distress syndrome (ARDS) requiring high frequency percussive ventilation. Cardiac evaluation was significant for myocardial infarction and left ventricular function impairment. He completely recovered from the respiratory and cardiac failure. Neurological examinations showed abnormal signals on MRI in the semi-oval center and in the frontal cortex. Follow-up detected partial impairment of axonal fibers of the right external popliteal sciatic nerve. Paediatric cases of survival after H2S intoxication have been rarely reported. Such exposures can evolve to severe ARDS and benefit from high frequency percussive ventilation. Hypothermia and other metabolic abnormalities are now better explained thanks to actual knowledge about endogenous H2S function. Lessons learned from paediatric accidents should result in better information about this threat for farmers and families living in houses with septic tanks, reducing the risk to their own and their children's safety.

Myocardial and lung injuries induced by hydrogen sulfide and the effectiveness of oxygen therapy in rats

OBJECTIVE

To study myocardial and lung injuries initiated by hydrogen sulfide, and evaluate the role and effectiveness of normobaric and hyperbaric oxygen (HBO) treatment in rats.

METHODS

One hundred healthy male Wistar rats were randomly divided into five groups: A: Normal control group (no H2S); B: H2S-exposed group; C: H2S+33% oxygen treatment group; D: H2S+50% oxygen treatment group; E: H2S+HBO group. The rats in groups C, D and E were exposed to H2S in an exposure chamber (1 m3) and were made to inhale 300 ppm hydrogen sulfide for 60 min, and then they were subjected to normobaric or HBO therapy. Normobaric oxygen was at concentrations of 33% or 50%, HBO was for 100 min including compression and decompression; the rats in group A inhaled air under the same conditions. Blood was sampled immediately after the experiment for analysis of arterial blood gases, myocardial enzymes and cardiac troponin I. Lung was rapidly removed to be made into tissue homogenates and then cytochrome c oxidase activity was measured; myocardial and lung ultrastructural changes were observed by electron microscopy.

RESULTS

Arterial blood gases: partial pressure of O2 (mmHg) (Group A, 97.6 ± 8.38; B, 76.5 ± 6.95*; C, 83.2 ± 2.66*; D, 86.20 ± 10.75*; E, 93.50 ± 4.97: *p < 0.01 compared to group A) was significantly lower than that in group in all but HBO rats. For myocardial enzymes and cardiac troponin I every parameter in groups B and C was significantly higher than that in group A (p<0.01),with no difference in D and E. Cytochrome c oxidase activity (u/mg) of lung tissue was reduced compared to group A after all treatments (A, 1.76 ± 0.02; B, 0.36 ± 0.04; C, 0.50 ± 0.12; D, 0.56 ± 0.07; E, 0.68 ± 0.05 (A vs. B p < 0.01; B vs. C,D,E p < 0.05 or p < 0.01), with a graded effect of oxygen dose in C, D and E. Pathological changes: (1) Myocardium - Mitochondrial swelling and autolysis with blurred or broken cristae was observed in the myocardium of H2S-exposed group; in group E, mitochondrial structure was basically normal, and clear cristae were found. (2) Lung tissue - In H2S-exposed group, alveolar epithelial cells disappeared, vacuolization of the organelle occurred, nuclear membrane was irregular and marginal condensation of heterochromatin was present; nucleus showed relatively normal morphology in group E, although some vacuoles still persisted within them.

CONCLUSIONS

HBO therapy can effectively improve arterial oxygen partial pressure, and significantly reduce myocardial damage, as well as potentially relieve lung injury in this model. Further work in humans appears warranted.

Chemical redox-regulated mesoporous silica-coated gold nanorods for colorimetric probing of Hg2+ and S2-

The past a few years have witnessed the wide use of metallic nanoparticles as ideal reporters for colorimetric detection, which generally involves an analyte-triggered alteration of aggregation degree of applied nanoparticles, and thus the change of colloidal color. However, these aggregation-based colorimetric probe are associated with a number of drawbacks, including poor stability of nanoaggregates, requirement of complicated functionalization and non-linearity of output signals. To address these problems, we herein employ mesoporous silica-coated gold nanorods (MS AuNRs) as novel nanocomposites for non-aggregation-based label-free colorimetric sensing relying on their chemical redox-modulated surface chemistry. In our sensing system, Hg(2+) ions are reduced to Hg(0) depositing on the surface of MS AuNPs and result in a great color change of MS AuNRs, while the subsequent introduction of S(2-) leads to a reverse process owing to the extraction of Hg(0) by S(2-). The experimental results for colorimetric sensing of Hg(2+) and S(2-) imply considerable sensitivity and specificity, suggesting the high potential of our approach for rapid environmental monitoring and bioanalysis in the future.