Interaction among Hydrogen Sulfide and Other Gasotransmitters in Mammalian Physiology and Pathophysiology.

Hydrogen sulfide (H2S), nitric oxide (NO), carbon monoxide (CO), and sulfur dioxide (SO2) were previously considered as toxic gases, but now they are found to be members of mammalian gasotransmitters family. Both H2S and SO2 are endogenously produced in sulfur-containing amino acid metabolic pathway in vivo. The enzymes catalyzing the formation of H2S are mainly CBS, CSE, and 3-MST, and the key enzymes for SO2 production are AAT1 and AAT2. Endogenous NO is produced from L-arginine under catalysis of three isoforms of NOS (eNOS, iNOS, and nNOS). HO-mediated heme catabolism is the main source of endogenous CO. These four gasotransmitters play important physiological and pathophysiological roles in mammalian cardiovascular, nervous, gastrointestinal, respiratory, and immune systems. The similarity among these four gasotransmitters can be seen from the same and/or shared signals. With many studies on the biological effects of gasotransmitters on multiple systems, the interaction among H2S and other gasotransmitters has been gradually explored. H2S not only interacts with NO to form nitroxyl (HNO), but also regulates the HO/CO and AAT/SO2 pathways. Here, we review the biosynthesis and metabolism of the gasotransmitters in mammals, as well as the known complicated interactions among H2S and other gasotransmitters (NO, CO, and SO2) and their effects on various aspects of cardiovascular physiology and pathophysiology, such as vascular tension, angiogenesis, heart contractility, and cardiac protection.

Non-prescription cold and flu medication-induced transient myopia with uveal effusion: case report.

BACKGROUND: To report a case of non-prescription cold and flu medication-induced transient myopia with uveal effusion. CASE PRESENTATION: Bilateral high intraocular pressure, shallow anterior chambers, uveal effusion, and a myopic shift were encountered in a 39-year-old Chinese male 1 night after taking a non-prescription flu medicine three times than the recommended dose. Ultrasound biomicroscopy (UBM) showed bilateral ciliochoroidal effusions, disappearance of the ciliary sulcus, closure of the angle of the anterior chamber, and anterior displacement of the lens-iris diaphragm. Treatment with aqueous suppressants was given. Within a week, the uncorrected vision restored, and the myopia had disappeared. UBM revealed major resolution of the ciliochoroidal effusions in both eyes, deepening of the anterior chamber, return of the lens-iris diaphragm to a more posterior position. CONCLUSIONS: Overdose of non-prescription cold and flu medication may cause bilateral uveal effusions inducing acute angle-closure glaucoma and acute myopia.

[Cardiovascular Regulation by Sulfur-containing Gaseous Signaling Molecules and the Underlying Mechanisms:Updated Research Evidence].

The sulfur-containing gases hydrogen sulfide (H2S)and sulfur dioxide (SO2 )were previously considered to be waste gases. Recent studies showed that they could be endogenously generated from metabolism of the sulfur-containing amino acids in mammals. Endogenous H2S and SO2 generation pathways also existed in the cardiovascular system.H2S and SO2 had important physiological effects in the cardio-vascular system including vasorelaxation and myocardial negative inotropic effect. The pathophysiological effects of H2S and SO2 in the cardiovascular system have been recognized, such as alleviating hypertension and pulmonary hypertension, inhibiting the development of atherosclerosis, and protecting against myocardial ischemia-reperfusion (I /R)injury and isoproterenol-induced myocardial injury. Adenosine triphosphate-sensitive potassium (KATP )channel, L-type calcium (L-Ca2 +) channel, cGMP, NF-κB signaling pathway and MAPK signaling pathway and so on participated in the biological effects of H2S and SO2 .The above findings suggested that H2S and SO2 were important endogenous gaseous signaling molecules in the cardiovascular system, which provided a new way to elucidate the pathogenesis and therapeutic targets of cardiovascular diseases.

Age and mean platelet volume-based nomogram for predicting the therapeutic efficacy of metoprolol in Chinese pediatric patients with vasovagal syncope.

BACKGROUND: Vasovagal syncope (VVS) is the most common type of orthostatic intolerance in children. We investigated whether platelet-related factors related to treatment efficacy in children suffering from VVS treated with metoprolol. METHODS: Metoprolol-treated VVS patients were recruited. The median duration of therapy was three months. Patients were followed and divided into two groups, treament-effective group and treatment-ineffective group. Logistic and least absolute shrinkage selection operator regressions were used to examine treatment outcome variables. Receiver-operating characteristic (ROC) curves, precision-recall (PR) curves, calibration plots, and decision curve analyses were used to evaluate the nomogram model. RESULTS: Among the 72 patients who complete the follow-up, treatment-effective group and treatment-ineffective group included 42 (58.3%) and 30 (41.7%) cases, respectively. The patients in the treatment-effective group exhibited higher mean platelet volume (MPV) [(11.0 ± 1.0) fl vs. (9.8 ± 1.0) fl, P < 0.01] and platelet distribution width [12.7% (12.3%, 14.3%) vs. 11.3% (10.2%, 12.2%), P < 0.01] than those in the treatment-ineffective group. The sex ratio was significantly different (P = 0.046). A fit model comprising age [odds ratio (OR) = 0.766, 95% confidence interval (CI) = 0.594-0.987] and MPV (OR = 5.613, 95% CI = 2.297-13.711) might predict therapeutic efficacy. The area under the curve of the ROC and PR curves was computed to be 0.85 and 0.9, respectively. The P value of the Hosmer-Lemeshow test was 0.27. The decision curve analysis confirmed that managing children with VVS based on the predictive model led to a net advantage ranging from 0.01 to 0.58. The nomogram is convenient for clinical applications. CONCLUSION: A novel nomogram based on age and MPV can predict the therapeutic benefits of metoprolol in children with VVS.

[Effect of blood-letting puncture of "Well-points" on hippocampal mitophagy-related protein expression in rats with acute brain injury due to hypobaric hypoxia].

OBJECTIVE: To study the effect of blood-letting puncture at "Well-points" of the twelve meridians on hippocampal mitophagy of hypobaric hypoxia-induced brain injury (HHIBI) rats, so as to explore its biological mechanisms underlying improvement of high altitude hypoxia-induced brain injury. METHODS: Male SD rats were randomly divided into normal control group （n=9）， and model and blood-letting groups which were further divided into 6, 12, 24, 48 and 72 h subgroups (n=9 in each subgroup). The HHIBI model was established by putting the rats into a hypobaric hypoxia chamber (equivalent to 5 000 m above sea level).The blood-letting groups were given blood-letting therapy at "Shaoshang"(LU11), "Shangyang"(LI1), "Zhongchong"(PC9), "Guanchong"(SJ1), "Shaochong"(HT9), "Shaoze"(SI9), once a day for 7 days. H.E. staining was used to observe the histopatholo-gical changes of hippocampus tissue. Serum hypoxia inducible factor(HIF)-1α and vascular endothelial growth factor(VEGF) contents were assayed using ELISA, and the expression levels of hippocampal Beclin-1 and LC3-Ⅱ proteins detected using Western blot. RESULTS: Compared with the normal control group, the levels of serum HIF-1α and VEGF at each time point, and the expressions of hippocampal Beclin-1 at 12 and 24 h, LC3-Ⅱat each time point were significantly increased in the model group (P<0.05, P<0.01); while in comparison with the model group, the levels of serum HIF-1α and VEGF contents, and the expressions of Beclin-1 at 12 h, LC3-Ⅱ at 24, 48 and 72 h were further significantly up-regulated in the blood-letting group (P<0.01, P<0.05). H.E. staining revealed that the pyramidal cells in the hippocampal CA1 region had a disordered arrangement, and some of them presented swelling with loose and pale cytoplasm or vacuolation at 6, 12 and 24 h, and showed indistinct nucleolus, irregular shape, pyknosis and deep staining and an obvious edema at 48 and 72 h, which was relatively milder in the blood-letting group. CONCLUSION: Blood-letting of "Well-points" can up-regulate serum HIF-1α and VEGF contents and hippocampal Beclin-1 and LC3-Ⅱ (mitophagy related proteins) expressions in HHIBI rats, which may contribute to its effect in reducing hypoxic brain injury.

Baseline left ventricular ejection fraction associated with symptom improvements in both children and adolescents with postural tachycardia syndrome under metoprolol therapy.

BACKGROUND: Postural tachycardia syndrome (POTS) is a common childhood disease that seriously affects the patient's physical and mental health. This study aimed to investigate whether pre-treatment baseline left ventricular ejection fraction (LVEF) and left ventricular fractional shortening (LVFS) values were associated with symptom improvement after metoprolol therapy for children and adolescents with POTS. METHODS: This retrospective study evaluated 51 children and adolescents with POTS who received metoprolol therapy at the Peking University First Hospital between November 2010 and July 2019. All patients had completed a standing test or basic head-up tilt test and cardiac echocardiography before treatment. Treatment response was evaluated 3 months after starting metoprolol therapy. The pre-treatment baseline LVEF and LVFS values were evaluated for correlations with decreases in the symptom score after treatment (ΔSS). Multivariable analysis was performed using factors with a P value of <0.100 in the univariate analyses and the demographic characteristics. RESULTS: A comparison of responders and non-responders revealed no significant differences in demographic, hemodynamic characteristics, and urine specific gravity (all P > 0.050). However, responders had significantly higher baseline LVEF (71.09% ±â€Š4.44% vs. 67.17% ±â€Š4.88%, t = -2.789, P = 0.008) and LVFS values (40.00 [38.00, 42.00]% vs. 36.79% ±â€Š4.11%, Z = -2.542, P = 0.010) than the non-responders. The baseline LVEF and LVFS were positively correlated with ΔSS (r = 0.378, P = 0.006; r = 0.363, P = 0.009), respectively. Logistic regression analysis revealed that LVEF was independently associated with the response to metoprolol therapy in children and adolescents with POTS (odds ratio: 1.201, 95% confidence interval: 1.039-1.387, P = 0.013). CONCLUSIONS: Pre-treatment baseline LVEF was associated with symptom improvement after metoprolol treatment for children and adolescents with POTS.

[Diabetic cardiomyopathy].

Diabetic cardiomyopathy is characterized by myocardial hypertrophy and fibrosis independent of hypertension, coronary artery disease or other idiopathic heart diseases. The underlying mechanisms of diabetic cardiomyopathy are still elusive. Previous studies have highlighted the importance of metabolic disturbances (dysfunction of glucose transporters, increased free fatty acids, abnormal changes in calcium homeostasis, disordered copper metabolism, insulin resistance), myocardial fibrosis (association with hyperglycemia, myocyte apoptosis, increases in angiotensin II , IGF-1, and pro-inflammatory cytokines, changes in matrix metalloproteinases activity etc.), cardiac autonomic neuropathy, and stem cell in the evolution of diabetic cardiomyopathy. The current overview will focus on the recent advance of pathogenesis of diabetic cardiomyopathy and may help to define the pathology of diabetes related heart diseases.

Inhibitory Effects of Sulfur Dioxide on Rat Myocardial Fibroblast Proliferation and Migration.

BACKGROUND: Myocardial fibrosis is an important pathological change in many heart diseases, but its pathogenesis is very complex and has not yet been fully elucidated. The study was designed to examine whether endogenous sulfur dioxide (SO2) is a novel myocardial fibroblast proliferation and migration inhibitor. METHODS: Primary rat myocardial fibroblasts were isolated and transfected with aspartate aminotransferase (AAT1 and AAT2) knockdown lentivirus or empty lentivirus. SO2 content in the supernatant was determined with high-performance liquid chromatography, and the expressions of AAT1, AAT2, proliferating cell nuclear antigen (PCNA), phosphorylated extracellular signal-regulated protein kinase (p-ERK), and total ERK (T-ERK) in the cells were detected. Cell migration was detected by wound healing test. Independent sample t-test (for two groups) and one-way analysis of variance (three or more groups) were used to analyze the results. RESULTS: Both AAT1 and AAT2 knockdown significantly reduced SO2levels (F = 31.46, P < 0.01) and AAT1/2 protein expression (AAT1, t = 12.67, P < 0.01; AAT2, t = 9.61, P < 0.01), but increased PCNA expression and Cell Counting Kit-8 (CCK-8) activity as well as the migration in rat primary myocardial fibroblasts (P < 0.01). Supplementation of SO2rather than pyruvate significantly inhibited the increase in proliferation and migration caused by AAT knockdown (P < 0.01). Mechanistically, the ratio of p-ERK to T-ERK was significantly increased in the AAT1/2 knockdown groups compared with that in the empty lentivirus group (AAT1, t = -7.36, P < 0.01; AAT2, t = -10.97, P < 0.01). Whereas PD98059, an inhibitor of ERK activation, successfully blocked AAT knockdown-induced PCNA upregulation (F = 74.01, P > 0.05), CCK-8 activation (F = 50.14, P > 0.05), and migration augmentation in myocardial fibroblasts (24 h, F = 37.08, P > 0.05; 48 h, F = 58.60, P > 0.05). CONCLUSION: Endogenous SO2might be a novel myocardial fibroblast proliferation and migration inhibitor via inhibiting the ERK signaling pathway.

Hydrogen Sulfide Regulating Myocardial Structure and Function by Targeting Cardiomyocyte Autophagy.

OBJECTIVE: Hydrogen sulfide (H2S), a gaseous signal molecule, plays a crucial role in many pathophysiologic processes in the cardiovascular system. Autophagy has been shown to participate in the occurrence of many cardiac diseases. Increasing evidences indicated that H2S regulates myocardial structure and function in association with the altered autophagy and plays a "switcher" role in the autophagy of myocardial diseases. The aim of this review was to summarize these insights and provide the experimental evidence that H2S targets cardiomyocyte autophagy to regulate cardiovascular function. DATA SOURCES: This review was based on data in articles published in the PubMed databases up to October 30, 2017, with the following keywords: "hydrogen sulfide," "autophagy," and "cardiovascular diseases." STUDY SELECTION: Original articles and critical reviews on H2S and autophagy were selected for this review. RESULTS: When autophagy plays an adaptive role in the pathogenesis of diseases, H2S restores autophagy; otherwise, when autophagy plays a detrimental role, H2S downregulates autophagy to exert a cardioprotective function. For example, H2S has beneficial effects by regulating autophagy in myocardial ischemia/reperfusion and plays a protective role by inhibiting autophagy during the operation of cardioplegia and cardiopulmonary bypass. H2S postpones cardiac aging associated with the upregulation of autophagy but improves the left ventricular function of smoking rats by lowering autophagy. CONCLUSIONS: H2S exerts cardiovascular protection by regulating autophagy. Cardiovascular autophagy would likely become a potential target of H2S therapy for cardiovascular diseases.

Sulfur Dioxide Inhibits Extracellular Signal-regulated Kinase Signaling to Attenuate Vascular Smooth Muscle Cell Proliferation in Angiotensin II-induced Hypertensive Mice.

BACKGROUND: Clarifying the mechanisms underlying vascular smooth muscle cell (VSMC) proliferation is important for the prevention and treatment of vascular remodeling and the reverse of hyperplastic lesions. Previous research has shown that the gaseous signaling molecule sulfur dioxide (SO2) inhibits VSMC proliferation, but the mechanism for the inhibition of the angiotensin II (AngII)-induced VSMC proliferation by SO2has not been fully elucidated. This study was designed to investigate if SO2inhibited VSMC proliferation in mice with hypertension induced by AngII. METHODS: Thirty-six male C57 mice were randomly divided into control, AngII, and AngII + SO2groups. Mice in AngII group and AngII + SO2group received a capsule-type AngII pump implanted under the skin of the back at a slow-release dose of 1000 ng·kg-1·min-1. In addition, mice in AngII + SO2received intraperitoneal injections of SO2donor. Arterial blood pressure of tail artery was determined. The thickness of the aorta was measured by elastic fiber staining, and proliferating cell nuclear antigen (PCNA) and phosphorylated-extracellular signal-regulated kinase (P-ERK) were detected in aortic tissues. The concentration of SO2 in serum and aortic tissue homogenate supernatant was measured using high-performance liquid chromatography with fluorescence determination. In the in vitro study, VSMC of A7R5 cell lines was divided into six groups: control, AngII, AngII + SO2, PD98059 (an inhibitor of ERK phosphorylation), AngII + PD98059, and AngII + SO2 + PD98059. Expression of PCNA, ERK, and P-ERK was determined by Western blotting. RESULTS: In animal experiment, compared with the control group, AngII markedly increased blood pressure (P < 0.01) and thickened the aortic wall in mice (P < 0.05) with an increase in the expression of PCNA (P < 0.05). SO2, however, reduced the systemic hypertension and the wall thickness induced by AngII (P < 0.05). It inhibited the increased expression of PCNA and P-ERK induced by AngII (P < 0.05). In cell experiment, PD98059, an ERK phosphorylation inhibitor, blocked the inhibitory effect of SO2on VSMC proliferation (P < 0.05). CONCLUSIONS: ERK signaling is involved in the mechanisms by which SO2inhibits VSMC proliferation in AngII-induced hypertensive mice via ERK signaling.