Making and working with hydrogen sulfide: The chemistry and generation of hydrogen sulfide in vitro and its measurement in vivo: A review

Hydrogen sulfide is rapidly emerging as an important vasoactive mediator formed in health and disease. Its biological action is centered on its reactivity with heme-proteins and its ability to activate K_ATP channels. Hydrogen sulfide is a signalling molecule of the inflammatory and nervous systems, and in particular the cardiovascular system where it regulates vascular tone, cardiac work, and exerts cardioprotection.This has led to an explosion of papers in which the role of hydrogen sulfide generated in vitro has been used to stimulate biological responses, and where a variety of methods have been used to measure the concentration of this compound in biological fluids. Understanding the chemistry and the inherent problems in the analytical techniques used to measure hydrogen sulfide concentrations is critical to our expanding knowledge on the biology of hydrogen sulfide. In this brief review we will cover the chemistry of hydrogen sulfide, including sources of hydrogen sulfide, its speciation at physiological pH, the susceptibility of sulfide to aerobic oxidation, and the methods used to measure hydrogen sulfide concentrations in solution, including biological fluids. We also give a brief overview of knockout animals and inhibition of the enzymes involved in the formation of hydrogen sulfide in vivo.     

Arabica coffee and olive oils mitigate malathion-induced nephrotoxicity in rat: In silico,immunohistochemical and biochemical evaluation

Malathion (MAL) is an organophosphate insecticide that disrupts the body's antioxidant system; it is one of the earliest organophosphate insecticides extensively used as dust, emulsion, and vapor control a wide variety of insect pests under different conditions. This experimentation aims to evaluate the influence of Arabica coffee oil and olive oil on MAL-induced nephrotoxicity in male rat. 6 sets bearing the same number of animals were applied to this experiment. Each set comprised 10 rats. The first set of rats was used as the control group; rats in the second set were exposed to MAL measured at 100 mg/kg body weight for 7 weeks. Animals in the third and fourth set were treated with 400 mg/kg body weight of Arabica coffee oil and olive oil, and 100 mg/kg body weight of MAL. The fifth, together with the sixth set, were fed with a similar proportion of Arabica coffee oil and olive oil as administered to the third set of rats. After the experimental duration, rats of group 2 showed severe biochemical alterations, including significant increases of creatinine, uric acids, and urea nitrogen (BUN), resulting in marked decreases in serum albumin values and total protein (TP). Severe histopathological and immunohistochemical alterations of kidney tissues were observed in exposed MAL-intoxicated rats. Administration of these oils reduced the detected biochemical, histopathological modifications caused by MAL intoxication. Two active ingredients in Arabica coffee oil (oleic acid) and olive oil (hydroxytyrosol) showed good cyclooxygenase-2 (COX 2) interaction. Moreover, oleic acid from coffee oil and olive oil exhibited impressive association with xanthine oxidase (XO). The current finding showed that coffee oil and olive oil could be appraised as possible and a likely deterrence component against nephrotoxicity brought about by MAL.     

Non-aerated cultivation ofHalobacterium cutirubrum and its effect on cellular squalenes

Summary Halobacterium cutirubrum was successfully cultivated under aerobic and microaerobic conditions. The early stationary phase of growth was obtained at 2.2 days and 45–55 days for aerated and non-aerated cultures, respectively. The dry cell yields were 0.7–1.2 gm/l in all preparations grown to early stationary growth phase. The cellular ratio of squalene to dihydro- and tetra-hydrosqualene decreased proportionately with decreased aeration rates.     

The use of disposable gaas generating kits for the growth of hydrogen-oxidizing bacteria and the determination of hydrogen autotrophy

A simplified procedure for the determination of autotropic growth of hydrogen-oxidizing bacteria has been developed. The method uses commercially available disposable hydrogen and carbon dioxide kits, commonly used in anaerobic bacteriology, to produce a gaseous atmosphre containing by volume approximately 41% hydrogen, 6% carbon dioxide, 11% oxygen and 42% nitrogen. The atmosphere was suitable for the growth of strains assigned to the species Alcaligenes eutrophus, Alcaligenes paradoxus, Paracoccus denitrificans, Pseudomonas facilis, Pseudomonas flava, Pseudomonas palleronii, Pseudomonas saccahrophilia and Rhodococcus sp. (‘Nocardia opaca’). The method can also be used for the screening of hydrogen-oxidizing ability in bacterial isolates, thus eliminating the need for complex gas mixing devices or expensive gas mixtures.     

不同纤维桩表面处理方式对牙根修复后抗折裂强度的影响

目的:探讨不同纤维桩表面处理方式对牙根修复后抗折裂强度的影响。方法:收集行正畸拔除的前磨牙120颗作为本研究样本,随机将120个纤维桩分为对照组、喷砂组和过氧化氢酸蚀组,每组40例。对照组纤维桩表明不给予任何处理,喷砂组给予氧化铝砂粒持续喷砂粗化处理,过氧化氢酸蚀组给予10%过氧化氢溶液处理,均包埋于纤维桩道预备好的离体牙内,采用相同树脂制备成核,行全冠修复与黏固,再模拟口腔内部环境给予样本牙冷热循环处理,经相同环境加载后,置于电子万能实验机获取样本牙抗折裂强度数据。对比三组离体牙样本体型数据、离体牙断裂方式、抗折裂强度,对三组进行为期24个月的定期随访,统计三组修复体断裂率,并采用Kaplan-Meier曲线和Log Rank法分析三组的生存状况。结果:三组的离体牙样本关于牙齿长度、牙根长度、颈部颊舌径及颈部近远中径对比差异无统计学意义(P0.05);喷砂组和过氧化氢酸蚀组的离体牙抗折裂强度显著强于对照组(P0.05);喷砂组和过氧化氢酸蚀组的牙齿折裂总发生率分别为20.00%和22.50%,均显著低于对照组的70.00%(P0.05)。但两组间比较差异无统计学意义(P0.05)。喷砂组、过氧化氢酸蚀组的生存状况显著优于对照组。结论:前磨牙修复过程中,对纤维桩表面进行喷砂或过氧化氢酸蚀处理均能提高牙根修复后抗折裂强度,改善修复体修复效果生存状况,且两种纤维桩表面处理方式对离体牙样本的断裂方式和抗折裂强度影响相当。     

脓毒症患者血清H2S、GDF-15、PTX-3水平与凝血功能、炎症指标及病情评分的相关性分析

摘要 目的：探讨脓毒症患者血清硫化氢（H₂S）、生长分化因子-15（GDF-15）、穿透素-3（PTX-3）水平与其凝血功能、炎症指标及病情评分的相关性。方法：随机选取我院2018年2月～2020年2月收治的脓毒症患者52例作为脓毒症组,另选取我院同期收治的脓毒症休克患者46例作为休克组以及同期于我院进行体检的健康者50例作为对照组。检测三组血清H₂S、GDF-15、PTX-3水平以及凝血功能、炎症指标,其中凝血功能指标包括血小板计数（PLT）、部分凝血活酶时间（APTT）、凝血酶原时间（PT）、纤维蛋白原（FIB）。炎症指标包括降钙素原（PCT）、C反应蛋白（CRP）。采用急性生理学和慢性健康状况评分系统Ⅱ（APACHEⅡ）、快速序贯器官功能（qSOFA）评分对脓毒症组、休克组患者病情进行评分。分析血清H2S、GDF-15、PTX-3与患者凝血功能、炎症指标及病情评分的相关性。结果：脓毒症组、休克组的血清H₂S、PLT均低于对照组,且休克组低于脓毒症组（P＜0.05）。脓毒症组、休克组的血清GDF-15、PTX-3、APTT、PT、FIB、PCT、CRP均高于对照组,且休克组高于脓毒症组（P＜0.05）。脓毒症组APACHEⅡ、qSOFA评分均显著低于休克组（P＜0.05）。血清H2S与PLT呈正相关（P＜0.05）,与APTT、PT、FIB、PCT、CRP、APACHEⅡ评分、qSOFA评分呈负相关（P＜0.05）。血清GDF-15、PTX-3与PLT呈负相关（P＜0.05）,与APTT、PT、FIB、PCT、CRP、APACHEⅡ评分、qSOFA评分呈正相关（P＜0.05）。结论：脓毒症患者的血清H₂S明显下降,而血清GDF-15、PTX-3增高,三者与凝血功能、炎症以及病情评分均存在密切关联,这可能是影响脓毒症进展的重要原因之一。     

Lipid-dependent sequential allosteric activation of heat-sensing TRPV1 channels by anchor-stereoselective “hot” vanilloid compounds and analogs

Both a silent resident phosphatidylinositol lipid and a “hot” vanilloid agonist capsaicin or resiniferatoxin have been shown to share the same inter-subunit binding pocket between a voltage sensor like domain and a pore domain in TRPV1. However, how the vanilloid competes off the resident lipid for allosteric TRPV1 activation is unknown. Here, the in silico research suggested that anchor-stereoselective sequential cooperativity between an initial recessive transient silent weak ligand binding site and a subsequent dominant steady-state strong ligand binding site in the vanilloid pocket may facilitate the lipid release for allosteric activation of TRPV1 by vanilloids or analogs upon non-covalent interactions. Thus, the resident lipid may play a critical role in allosteric activation of TRPV1 by vanilloid compounds and analogs.     

Peroxide Damage to the Eye Lens In Vitro Prevention by Pyruvate

The ability of pyruvate to protect the eye lens against physiological damage by hydrogen peroxide has been studied. The physiological damage was estimated in terms of a decrease in the ability of the lens to transport rubidium against an electrochemical gradient under organ culture conditions. Peroxide was either added directly to the culture medium or generated therein by incorporation of xanthine and xanthine oxidase. In both these cases, addition of pyruvate to the medium led to a greater accumulation of rubidium by the lens. The net accumulation of this cation in the presence of 1 to 5 mM pyruvate from the medium containing peroxide (0.2 to 0.45 mM) was very close to that observed in the absence of peroxide. The protective effect was thus substantial. The mechanism of the pyruvate effect has been discussed, and seems to be related to the scavenging of peroxide by pyruvate.     

Kinetics and Mechanism of the Reaction of a Nitroxide Radical (Tempol) With a Phenolic Antioxidant

In the absence of redox-active transition metal ions, the removal of Tempol by Trolox occurs by a simple bimolecular reaction that, most probably, involves a hydrogen transfer from phenol to nitroxide. The specific rate constant of the process is small (0.1 M &#109 1 s &#109 1 ). Metals can catalyze the process, as evidenced by the decrease in rate observed in the presence of diethylenetriaminepentaacetic acid (DTPA). Furthermore, addition of Fe(II) (20 &#119 M ferrous sulfate and 40 &#119 M EDTA) produces a noticeable increase in the rate of Tempol consumption.     

Pyruvate secreted by human lymphoid cell lines protects cells from hydrogen peroxide mediated cell death

Reactive oxygen species (ROS) released from polymorphonuclear leukocytes and macrophages could cause DNA damage, but also induce cell death. Therefore inhibition of cell death must be an important issue for accumulation of genetic changes in lymphoid cells in inflammatory foci. Scavengers in the post culture medium of four lymphoid cell lines, lymphoblastoid cell lines (LCL), Raji, BJAB and Jurkat cells, were examined. Over 80% of cultured cells showed cell death 24 h after xanthine (X)/xanthine oxidase (XOD) treatment, which was suppressed by addition of post culture medium from four cell lines in a dose-dependent manner. H₂O₂ but not O^·-₂ produced by the X/XOD reaction was responsible for the cytotoxity, thus we used H₂O₂ as ROS stress thereafter. The H₂O₂-scavenging activity of post culture media from four cell lines increased rapidly at the first day and continued to increase in the following 2–3 days for LCL, Raji and BJAB cells. The scavenging substance was shown to be pyruvate, with various concentrations in the cultured medium among cell lines. Over 99% of total pyruvate was present in the extracellular media and less than 1% in cells. α-Cyano-4-hydroxycinnamate, a specific inhibitor of the H⁺-monocarbohydrate transporter, increased the H₂O₂-scavenging activity in the media from all four cell lines via inhibition of pyruvate re-uptake by cultured cells from the media. These findings suggest that lymphoid cells in inflammatory foci could survive even under ROS by producing pyruvate, so that accumulation of lymphoid cells with DNA damage is possible.