Reduced Hydrogen Sulfide Research Articles

Effectiveness of a combination of laccase and green coffee extract on oral malodor: A comparative, randomized, controlled, evaluator-blind, parallel-group trial.

Oral malodor negatively impacts a person's quality of life and may affect up to 50% of the population. The aim of this randomized, placebo and no-product controlled, evaluator-blind, proof-of-concept study was to evaluate the effectiveness and safety of the single use of two experimental lozenges containing the laccase enzyme and green coffee extract (with and without flavor) in reducing intrinsic oral malodor. Following 12 to 16 h of avoidance of oral hygiene,156 generally healthy subjects presented at screening and baseline visits with a mean organoleptic odor intensity (OI) score of ≥ 2 and an OralChromaTMreading of ≥ 125 parts per billion (ppb) hydrogen sulfide (H2S) gas and were randomly assigned to receive either one of the two experimental lozenges, a placebo lozenge, or no-product. Following the supervised use of the assigned products, subjects' oral malodor was evaluated using OI assessments and OralChromaTMmeasurement for volatile sulfur compounds (VSCs) immediately following product use (approximately 5 min), and at 30 min, 1 h, 2 h, 3 h and 4 h. The two experimental lozenges, with and without flavor, showed significant reductions in OI scores compared with the placebo and no-product groups at all time points (p < 0.001). At 5 minutes post-product use, the experimental lozenges, with and without flavor, were significantly better than the no-product group in reducing the VSCs (p < 0.04). The results of individual VSC components (hydrogen sulfide, methyl mercaptan and dimethyl sulfide) were variable; both experimental lozenges notably reduced hydrogen sulfide and methyl mercaptan levels in most post-use assessments. Four minor adverse events were reported, none of which were directly linked to the product. In conclusion, the experimental lozenges, whether flavored or not, were safe and effective in reducing oral malodor over a span of 4 h, based on organoleptic OI scores.&#xD;NCT05950529.

Reduced Hydrogen Sulfide Bioavailability Contributes to Cardiometabolic Heart Failure with Preserved Ejection Fraction.

Heart failure with preserved ejection fraction (HFpEF) is a significant public health concern with limited treatment options. Dysregulated nitric oxide-mediated signaling has been implicated in HFpEF pathophysiology, however, little is known about the role of endogenous hydrogen sulfide (H2S). This study evaluated H2S bioavailability in patients and two animal models of cardiometabolic HFpEF and assessed the impact of H2S on HFpEF severity through alterations in endogenous H2S production and pharmacological supplementation. HFpEF patients and two rodent models of HFpEF ("two-hit" L-NAME + HFD mouse and ZSF1 obese rat) were evaluated for H2S bioavailability. Two cohorts of two-hit mice were investigated for changes in HFpEF pathophysiology: (1) endothelial cell cystathionine-γ-lyase (EC-CSE) knockout; (2) H2S donor, JK-1, supplementation. H2S levels were significantly reduced (i.e., 81%) in human HFpEF patients and in both preclinical HFpEF models. This depletion was associated with reduced CSE expression and activity, and increased SQR expression. Genetic knockout of H2S -generating enzyme, CSE, worsened HFpEF characteristics, including elevated E/e' ratio and LVEDP, impaired aortic vasorelaxation and increased mortality. Pharmacologic H2S supplementation restored H2S bioavailability, improved diastolic function and attenuated cardiac fibrosis corroborating an improved HFpEF phenotype. H2S deficiency is evident in HFpEF patients and conserved across multiple HFpEF models. Increasing H2S bioavailability improved cardiovascular function, while knockout of endogenous H2S production exacerbated HFpEF pathology and mortality. These results suggest H2S dysregulation contributes to HFpEF and increasing H2S bioavailability may represent a novel therapeutic strategy for HFpEF. H2S deficiency is evident in both human HFpEF patients and two clinically relevant models.Reduced H2S production by CSE and increased metabolism by SQR impair H2S bioavailability in HFpEF.Pharmacological H2S supplementation improves diastolic function and reduces cardiac fibrosis in HFpEF models.Targeting H2S dysregulation presents a novel therapeutic strategy for managing HFpEF.

Innovative Sn-gradient sulfide solid electrolytes with superior air-stability for practical all-solid-state batteries

Sulfide solid electrolytes (SSEs) with high ionic conductivity and mechanical flexibility are considered promising Li+ transport media for all-solid-state batteries (ASSBs). However, susceptibility to moisture originating from their crystal structures degrades their inherent superior properties. In this study, we synthesized core–shell structured SSEs by inducing the growth of compounds with moisture-stable SnS44− units on the surface of Li6PS5Cl (LPSC). This Li10SnP2S12 (LSPS)@LPSC showed > 30 times higher Li+ conductivity than LPSC after exposure to dry room environment for 2 h. Additionally, the hydrolysis reaction was effectively inhibited in LSPS@LPSC, resulting in not only significant reduction of hydrogen sulfide (H2S) gas release, but the onset of its generation was also more delayed than in LPSC. Also, in LSPS@LPSC, the inhibition of P-O bond formation after moisture exposure contributes to retention of mechanical properties, as demonstrated by nano-indentation measurements: hardness changes from 1.42 GPa to 1.50 GPa for LSPS@LPSC versus from 1.21 GPa to 1.62 GPa for LPSC (dew point of −7.5 °C, 5 min). Furthermore, the Li(Ni0.8Co0.1Mn0.1)O2 cell with LSPS@LPSC exhibited excellent cycling stability comparable to that of LPSC under typical external pressure (30 MPa), and more remarkably, it showed superior cycle retention than LPSC cell under ultra-low external pressure (∼0.3 MPa).

Construction of a NIR hydrogen sulfide fluorescent probe for revealing the role of astrocytes in hypothalamic inflammation

Hydrogen sulfide (H2S) is a crucial endogenous gas signaling molecule in the central nervous system, playing a significant role in anti-inflammation, anti-oxidation, and neuroprotection. Our studies have shown that the level of H2S is closely related to hypothalamic inflammation-induced obesity. Compared to neurons, astrocytes, exhibit a preferential activation in response to high-fat diet-induced hypothalamic inflammation. Whether the reduction of hydrogen sulfide in astrocytes is the cause of neuronal damage leading to hypothalamic inflammation is worth exploring. The key to discussing the role of astrocytes is to accurately and quickly detect the levels of H2S in the complex microenvironment of the brain. In this work, we designed and synthesized a H2S near-infrared fluorescence probe (NIR-HS) based on dicyanideisophorone. NIR-HS selectively responds to H2S at 668 nm, with an effective linear range (0–20 μM), high sensitivity (35 nM). This probe has been successfully applied to detect hydrogen sulfide levels in astrocytes and to perform H2S fluorescence imaging on the slices of the ventromedial nucleus of the hypothalamus. Additionally, the effect of the H2S donor drug allicin on the levels of H2S in the hypothalamus and its therapeutic effect on hypothalamic inflammation were confirmed using NIR-HS and a series of signal pathway studies. Ultimately, we revealed the mechanism of that H2S inhibits hypothalamic neuronal inflammation by suppressing the expression of the pro-inflammatory factor IL-1β in astrocytes.

Sub-dew point claus process for reducing hydrogen sulfide emission from sulfur recovery units

Increasing the efficiency of the sulfur recovery and decreasing the hydrogen sulfide emission are significant from both economic and environmental aspects. The cold bed adsorption (CBA) process is an approach to address the above concerns. The bench scale CBA experiments including adsorption and regeneration stages at temperatures of 140 °C and 280 °C are investigated against an industrial scale modified Claus process by using a commercial Al2O3 catalyst. Implementing CBA increases the H2S conversion of a modified Claus process sulfur recovery unit about 5%, but it is not efficient to convert CS2 and COS to the elemental sulfur. Period times of 12, 7 and 3 h are appropriate for the adsorption, desorption and cooling stages, respectively. After cycles of CBA process, the surface area and pore volume of the commercial Al2O3 Claus catalyst decrease from 385 m2/g and 0.34 cm3/g to 337 m2/g and 0.31 cm3/g, respectively as a result of condensing the elemental sulfur inside its micro- and meso- pores. The proposed CBA process is applicable to reduce the H2S emission, CAPEX and OPEX of sulfur recovery units.

Effect of iron powder on hydrogen sulfide reduction and phosphate removal in semi‐continuous anaerobic digestion treating primary sludge

AbstractBACKGROUNDTo our best knowledge, no experimental study has previously investigated the simultaneous effects of adding Fe powder for the decrease of hydrogen sulfide (H2S) in biogas and the removal of phosphate (PO4‐P) in continuous anaerobic digestion (AD). This study investigated the effects of iron (Fe) powder (5 g L−1) in AD to remove H2S and PO4‐P. A comparative experiment was conducted using two semi‐continuous‐flow anaerobic digesters treating primary sludge at decreasing hydraulic retention times (HRTs) of 20 to 10 days.RESULTSThe addition of Fe powder to AD removed &gt; 98% of H2S at all HRTs, and removed 64–72% of PO4‐P, with the highest removal efficiency at HRT = 10 d. The addition of Fe powder to AD had no noticeable effect on biogas production or pH, but it increased the CH4 content (62.7–66.0% in Fe‐treated vs 58.2–60.4% in the Control) partly due to the greater presence of Methanoregulaceae. The relative abundance of the microbial groups was more affected by HRT than by the addition of Fe powder. The presence of Fe powder notably increased the abundance of Spirochaetaceae and Syntrophaceae.CONCLUSIONAs shown, the addition of Fe powder can improve the management of both H2S in the biogas and PO4‐P in the digested sludge in the AD system. © 2024 Society of Chemical Industry (SCI).

A Study on the Reduction of Hydrogen Sulfide in Biogas Facilities from Food Waste

A Study on the Reduction of Hydrogen Sulfide in Biogas Facilities from Food Waste

Effect of Photo Irradiation on the Anaerobic Digestion of Waste Sewage Sludge-Reduced Methane and Hydrogen Sulfide Productions

Since a large amount of sewage sludge (WSS) is generated daily, exploring effective methods for utilizing WSS is necessary. Although a photo-fermentation system sometimes alters the characteristics of microbial functions, there have been no attempts to perform photo-fermentation using WSS, which is regularly treated via dark fermentation. In this study, the effect of photo-fermentation (photo-irradiation) on anaerobic digestion using WSS was revealed. Photo-irradiation during the anaerobic digestion of WSS significantly reduced the amount of methane and hydrogen sulfide. Methane production was also reduced 5.6-fold at 13 days under light conditions, whereas hydrogen sulfide was consumed almost completely at 6 days. However, it was shown that the activity of sulfate-reducing bacteria in WSS under light treatment increased. Photo-irradiation also stimulated the growth of green sulfur bacteria and induced anoxygenic photosynthesis, via which process the fermented samples turned green in a manner that was correlated with their consumption of hydrogen sulfide. The production of organic acids was lowered in the samples that were irradiated using light. Finally, dark/light switching fermentation was only able to reduce hydrogen sulfide while methane production remained the same. The amounts of methane and hydrogen sulfide were 35 mmol/g VS, and they were undetected at 58 days in photo-irradiated samples compared to the control samples that produced 37 mmol/g VS of methane and 15 ppm/g VS of hydrogen sulfide.

Optimization of effecting parameters for flue gas desulfurization in a self‐priming venturi scrubber using response surface methodology

AbstractHydrogen sulfide (H2S), a highly poisonous and corrosive gas, is regarded as a hazardous air pollutant with significant effects on human health. Hence, reduction of hydrogen sulfide (H2S) gas from the atmosphere is very essential. In the present work, self‐priming venturi scrubber is employed to extract H2S gas from the air. Response surface methodology (RSM) with a central composite design (CCD) has been selected to investigate maximizing the H2S removal efficiency by optimizing the process variables. Experiments were carried out by altering the throat gas velocity, outer cylinder liquid level and inlet concentration of H2S. The analysis of variance (ANOVA) test showed that the parameters had a significant effect on the efficiency of H2S removal. A quadratic equation has been developed that accurately predicts the percentage of removal efficiency. The appropriateness of the generated model has been verified by the value of higher R2 resulting from the regression analysis. According to the observations, the velocity of throat gas has the highest effect on the H2S removal efficiency, whereas inlet H2S concentration has the least effect.

A biological strategy for sulfide control in sewers: Removing sulfide by sulfur-oxidizing bacteria

Sulfide produced from sewers is considered one of the dominant threats to public health and sewer lifespan due to its toxicity and corrosiveness. In this study, we developed an environmentally friendly strategy for gaseous sulfide control by enriching indigenous sulfur-oxidizing bacteria (SOB) from sewer sediment. Ceramics acted as bio-carriers for immobilizing SOB for practical use in a lab-scale sewer reactor. 16 S rRNA gene sequences revealed that the SOB consortium was successfully enriched, with Thiobacillus, Pseudomonas, and Alcaligenes occupying a dominant abundance of 64.7% in the microbial community. Metabolic pathway analysis in different acclimatization stages indicates that microorganisms could convert thiosulfate and sulfide into elemental sulfur after enrichment and immobilization. A continuous experiment in lab-scale sewer reactors confirmed an efficient result for sulfide removal with hydrogen sulfide reduction of 43.9% and 85.1% under high-sulfur load and low-sulfur load conditions, respectively. This study shed light on the promising application for sewer sulfide control by biological sulfur oxidation strategy.

Effect of nano zero-valent iron, potassium persulphate, and biochar on maturity and gaseous emissions during multi-material co-composting

Aerobic composting technology is expected to achieve higher quality composts. This study investigated the effects of exogenous additives on compost maturity and gaseous emissions during co-composting of pig manure and kitchen waste using nano zero-valent iron (NI), potassium persulphate (PS), cornstalk biochar (CB) and pig manure biochar (PB) additives. The results showed that CB and PB reduced electrical conductivity (EC) and increased compost maturity. All additives reduced total greenhouse gas emissions, including methane (CH4), by 28.6–71.5%, while only PB addition reduced nitrous oxide (N2O) emissions by 13.3%. PS addition resulted in the lowest pH value, and ammonia (NH3) emissions decreased by 53.1%. NI reduced hydrogen sulfide emissions by 20.4%. Additionally, all additive reduced dimethyl sulfide (Me2S) emissions by 18.6–44.2%,while they increased dimethyl disulfide (Me2SS) emissions by 7.6–150.6%. Therefore, these additives, especially PS, which exhibited superior performance, can cooperate to reduce greenhouse gas and odors emissions during composting.

Microbial electrolysis cell simultaneously enhancing methanization and reducing hydrogen sulfide production in anaerobic digestion of sewage sludge

The effects of microbial electrolysis cells (MECs) at three applied voltages (0.8, 1.3, and 1.6 V) on simultaneously enhancing methanization and reducing hydrogen sulfide (H2S) production in the anaerobic digestion (AD) of sewage sludge were studied. The results showed that the MECs at 1.3 V and 1.6 V simultaneously enhanced the methane production by 57.02 and 12.70% and organic matter removal by 38.77 and 11.13%, and reduced H2S production by 94.8 and 98.2%, respectively. MECs at 1.3 V and 1.6 V created a micro-aerobic conditions for the digesters with oxidation-reduction potential as −178∼-232 mv, which enhanced methanization and reduced H2S production. Sulfur reduction, H2S and elemental sulfur oxidation occurred simultaneously in the ADs at 1.3 V and 1.6 V. The relative abundances of sulfur-oxidizing bacteria increased from 0.11% to 0.42% and those of sulfur-reducing bacteria decreased from 1.24% to 0.33% when the applied voltage of MEC increased from 0 V to 1.6 V. Hydrogen produced by electrolysis enhanced the abundance of Methanobacterium and changed the methanogenesis pathway.

Serum hydrogen sulphide levels in acute asthmatic children: a case control study

BackgroundIt’s thought that respiratory epithelium-produced reduced hydrogen sulphide (H2S) plays a role in the pathophysiology of acute asthma. In this case–control research, blood H2S levels were examined between matched acutely asthmatic children and non-asthmatic controls. The grade of acute asthma, vital signs and absolute eosinophilic count in the asthmatic children were likewise associated with the blood H2S level.MethodsForty Egyptian asthmatic children had visited the emergency room and forty age- and sex-matched non-asthmatic controls had their blood H2S levels measured using enzyme-linked immunosorbent assay (ELISA).ResultsThe serum H2S in the two groups did not differ statistically significantly. Serum H2S and respiratory rate showed a moderately significant inverse connection (r = -0.325, p = 0.041). However, serum H2S and other clinical or laboratory variables exhibited no meaningful relationships. Patients' absolute and percentage eosinophil counts were considerably higher than healthy controls. Serum H2S exhibited a sensitivity of 50% and a specificity of 32.5% for identifying children with acute asthma from non-asthmatic children.ConclusionChildren with asthma and those without asthma had similar serum H2S levels. It has a lousy relationship with respiratory rate. It is indicated that it is an inadequate screening and diagnostic tool since it has low sensitivity (50%) and specificity (32.5%) in differentiating acute asthmatic children.

Enhancing sulfate reduction and hydrogen sulfide removal through gas stripping in the acidogenesis phase of a two-phase anaerobic process

This study aims at evaluating two-phase and single-phase reactors for treating sulfate wastewater with low COD/SO42− ratios. Additionally, a new process of gas stripping in an acidogenesis phase is proposed to reduce hydrogen sulfide (H2S) inhibition and enhance biomethanation. The two-phase performed better than the single-phase in terms of COD removal, CH4 production and H2S resistance. After 30 days of stripping, the COD and sulfate degradation rates increased from 85.16% to 91.09% and from 49.39% to 63.07% in the two-phase, respectively. In contrast, without stripping, they were from 79.21% to 64.37% and from 50.26% to 53.15% in the single-phase, respectively. The microbial biodiversity was augmented via stripping, including norank_f__Spirochaetaceae, Petrimonas, Desulfurella and Blvii28_wastewater-sludge_group. Stripping operation enhanced the dissimilatory sulfate reduction, amino acid metabolism and possibly sulfate-dependent anaerobic ammonia oxidation (S-ANAMMOX). This study provides a promising strategy to improve sulfate reduction and reduce H2S inhibition under a low COD/SO42− ratio.

Hydrogen sulfide inhibits lipopolysaccharide-based neuroinflammation-induced astrocyte polarization after cerebral ischemia/reperfusion injury

The effect of lipopolysaccharide (LPS)-based neuroinflammation following cerebral ischemia/reperfusion (I/R) on the genotypic transformation of reactive astrocytes and its relationship with endogenous hydrogen sulfide (H2S) were investigated in present study. We found that LPS promoted the cerebral I/R-induced A1 astrocytes proliferation in mouse hippocampal tissues and deteriorated the reduction of hydrogen sulfide (H2S) content in mouse sera, H2S donor NaHS could inhibit A1 astrocytes proliferation. Similarly, knockout of cystathionine γ-lyase (CSE), one of endogenous H2S synthases, likewise up-regulated the cerebral I/R-induced A1 astrocytes proliferation, which could also be blocked by NaHS. Besides, supplement with H2S promoted the A2 astrocytes proliferation in hippocampal tissues of CSE knockout (CSE KO) mice or LPS-treated mice following cerebral I/R. In the oxygen glucose deprivation/reoxygenation (OGD/R) model of astrocytes, H2S also promoted the transformation of astrocytes into A2 subtype. Moreover, we found that H2S could up-regulate the expression of α-subunit of large-conductance Ca2+-activated K+ (BKCa) channels in astrocytes, and the channel opener BMS-191011 likewise promoted the transformation of astrocyte into A2 subtype. In conclusion, H2S inhibits the proliferation of A1 astrocytes induced by LPS-based neuroinflammation following cerebral I/R and promotes the transformation of astrocytes into A2 subtype, which may be related to up-regulation of BKCa channels.

Interface engineering of sandwich SiO2@α-Fe2O3@COF core-shell S-scheme heterojunctions for efficient photocatalytic oxidation of gas-phase H2S

Hydrogen sulfide (H2S) is considered to be a broad-spectrum toxicant, and it is crucial to address this problem due to its serious health and climate change impacts. Photocatalysis can be effectively applied for the reduction of H2S molecules to S and other products. We synthesized sandwich-structured composite materials with internally immobilized SiO2 nanospheres and externally wrapped COF layers co-modified with iron oxide nanoparticles. Furthermore, originally looked at the efficiency of photocatalysis in reducing hydrogen sulfide to sulfur. In this paper, a sandwich structure of core–shell composite photocatalysts based on SiO2 was prepared by a multi-step method including Stöber and double ligand-regulated solvent heat, and these sandwich core–shell structures exhibited high hydrogen sulfide reduction and stability in applications. In addition, characterization, degradation studies, active substance trapping studies, and energy band structure analysis showed that S-type heterojunctions could effectively increase photo-generated carrier separation. This research advanced knowledge of photocatalytic hydrogen sulfide reduction and offered a novel approach for catalysts in COF sandwich core–shell structures.

Effect of Hydrogen Sulfide on Essential Functions of Polymorphonuclear Leukocytes.

Impaired polymorphonuclear leukocyte (PMNL) functions contribute to increased infections and cardiovascular diseases in chronic kidney disease (CKD). Uremic toxins reduce hydrogen sulfide (H2S) levels and the anti-oxidant and anti-inflammatory effects of H2S. Its biosynthesis occurs as a side process of transsulfuration and in the disposal of adenosylhomocysteine, a transmethylation inhibitor and proposed uremic toxin. PMNL chemotaxis was measured by the under-agarose method, phagocytosis, and oxidative burst by flow cytometry in whole blood and apoptosis by determining DNA content by flow cytometry and morphological features by fluorescence microscopy. Sodium hydrogen sulfide (NaHS), diallyl trisulphide (DATS) and diallyl disulphide (DADS), cysteine, and GYY4137 were used as H2S-producing substances. Increased H2S concentrations did not affect chemotaxis and phagocytosis. NaHS primed PMNL oxidative burst activated by phorbol 12-myristate 13-acetate (PMA) or E. coli. Both DATS and cysteine significantly decreased E. coli-activated oxidative burst but had no effect on PMA stimulation. While NaHS, DADS, and cysteine attenuated PMNL apoptosis, GYY4137 decreased their viability. Experiments with signal transduction inhibitors suggest that the intrinsic apoptosis pathway is mainly involved in GYY4137-induced PMNL apoptosis and that GYY4137 and cysteine target signaling downstream of phosphoinositide 3-kinase.

Coupling a biochar filter to a leach bed reactor for anaerobic digestion of chicken litter

In this study, coupling a biochar-packed anaerobic filter (AF) to a batch leach bed reactor (LBR) is investigated as a pragmatic method for biochar application to enhance high-solids anaerobic digestion of chicken litter. Recirculating leachate through a biochar filter reduced solid retention time by 45 % compared with a batch system without recirculation. The key benefit of biochar over inert filter media was the capability to reduce hydrogen sulfide production by 37 % overall; 25 % in the LBR, and 93 % in the AF. No significant differences in methane yield were observed. Biogas produced in the biochar AF was of higher quality with a maximum hydrogen sulfide content of 188 ppm and peak methane content of 73 %. However, majority of the biogas was produced in the LBR due to poor phase separation. Further research is required to increase biogas production in the AF and/or reduce hydrogen sulfide production in the LBR.

Reduced hydrogen sulfide production contributes to adrenal insufficiency induced by hypoxia via modulation of NLRP3 inflammasome activation

ABSTRACTObjective: Adrenocortical responsiveness is critical for maintaining glucocorticoids production and homeostasis during stress. We sought to investigate adrenocortical responsiveness during hypoxia in mice and the mechanisms responsible for the regulation of adrenal responsiveness.Methods: (1) Adult male WT mice were randomly divided into four groups: normoxia, hypoxia (24h), hypoxia (72h), hypoxia (72h) + GYY4137(hydrogen sulfide (H2S) donor, 133mmol/kg/day); (2) WT mice were randomly divided into four groups: sham, adrenalectomy (ADX), sham+hypoxia, ADX+hypoxia; (3) Cse-/- mice were randomly divided into two groups: Cse-/-, Cse-/- +GYY4137.Results: The circulatory level of corticosteroid induced by ACTH stimulation was significantly reduced in the mice with hypoxia compared with control mice. The mortality rate induced by lipopolysaccharide (LPS) increased during hypoxia. Cystathionine-γ-lyase (CSE) expression was significantly reduced in adrenal glands during hypoxia. GYY4137 treatment significantly increased adrenal responsiveness and attenuated NLRP3 inflammasome activation in mice treated by hypoxia and Cse-/- mice. Furthermore, The sulfhydrated level of PSMA7 in adrenal gland was decreased in the mice with hypoxia and Cse-/- mice. PSMA7 was S-sulfhydrated at cysteine 70. Blockage of S-sulfhydration of PSMA7 increased NLRP3 expression in adrenocortical cells.Conclusion: Reduced H2S production mediated hypo-adrenocortical responsiveness and NLRP3 inflammasome activation via PAMA7 S-sulfhydration during hypoxia.

Folic acid attenuates chronic visceral pain by reducing Clostridiales abundance and hydrogen sulfide production.

Irritable bowel syndrome (IBS) related chronic visceral pain affects 20% of people worldwide. The treatment options are very limited. Although the scholarly reviews have appraised the potential effects of the intestinal microbiota on intestinal motility and sensation, the exact mechanism of intestinal microbiota in IBS-like chronic visceral pain remains largely unclear. The purpose of this study is to investigate whether Folic Acid (FA) attenuated visceral pain and its possible mechanisms. Chronic visceral hyperalgesia was induced in rats by neonatal colonic inflammation (NCI). 16S rDNA analysis of fecal samples from human subjects and rats was performed. Patch clamp recording was used to determine synaptic transmission of colonic-related spinal dorsal horn. Alpha diversity of intestinal flora was increased in patients with IBS, as well as the obviously increased abundance of Clostridiales order (a main bacteria producing hydrogen sulfide). The hydrogen sulfide content was positive correlation with visceral pain score in patients with IBS. Consistently, NCI increased Clostridiales frequency and hydrogen sulfide content in feces of adult rats. Notably, the concentration of FA was markedly decreased in peripheral blood of IBS patients compared with non-IBS human subjects. FA supplement alleviated chronic visceral pain and normalized the Clostridiales frequency in NCI rats. In addition, FA supplement significantly reduced the frequency of sEPSCs of neurons in the spinal dorsal horn of NCI rats. Folic Acid treatment attenuated chronic visceral pain of NCI rats through reducing hydrogen sulfide production from Clostridiales in intestine.