Role of hydrogen sulfide in sulfur dioxide production and vascular regulation.

Both hydrogen sulfide (H2S) and sulfur dioxide (SO2) are produced endogenously from the mammalian metabolic pathway of sulfur-containing amino acids and play important roles in several vascular diseases. However, their interaction during the control of vascular function has not been fully clear. Here, we investigated the potential role of H2S in SO2 production and vascular regulation in vivo and in vitro. Wistar rats were divided into the vehicle, SO2, DL-propargylglycine (PPG) + SO2, ß-cyano-L-alanine (BCA) + SO2 and sodium hydrosulfide (NaHS) + SO2 groups. SO2 donor was administered with or without pre-administration of PPG, BCA or NaHS for 30 min after blood pressure was stabilized for 1 h, and then, the change in blood pressure was detected by catheterization via the common carotid artery. Rat plasma SO2 and H2S concentrations were measured by high performance liquid chromatography and sensitive sulfur electrode, respectively. The isolated aortic rings were prepared for the measurement of changes in vasorelaxation stimulated by SO2 after PPG, BCA or NaHS pre-incubation. Results showed that the intravenous injection of SO2 donors caused transient hypotension in rats compared with vehicle group. After PPG or BCA pretreatment, the plasma H2S content decreased but the SO2 content increased markedly, and the hypotensive effect of SO2 was significantly enhanced. Conversely, NaHS pretreatment upregulated the plasma H2S content but reduced SO2 content, and attenuated the hypotensive effect of SO2. After PPG or BCA pre-incubation, the vasorelaxation response to SO2 was enhanced significantly. While NaHS pre-administration weakened the SO2-induced relaxation in aortic rings. In conclusion, our in vivo and in vitro data indicate that H2S negatively controls the plasma content of SO2 and the vasorelaxant effect under physiological conditions.

Endothelial Cell-Derived SO2 Controls Endothelial Cell Inflammation, Smooth Muscle Cell Proliferation, and Collagen Synthesis to Inhibit Hypoxic Pulmonary Vascular Remodelling.

Hypoxic pulmonary vascular remodelling (PVR) is the major pathological basis of aging-related chronic obstructive pulmonary disease and obstructive sleep apnea syndrome. The pulmonary artery endothelial cell (PAEC) inflammation, and pulmonary artery smooth muscle cell (PASMC) proliferation, hypertrophy and collagen remodelling are the important pathophysiological components of PVR. Endogenous sulfur dioxide (SO2) was found to be a novel gasotransmitter in the cardiovascular system with its unique biological properties. The study was aimed to investigate the role of endothelial cell- (EC-) derived SO2 in the progression of PAEC inflammation, PASMC proliferation, hypertrophy and collagen remodelling in PVR and the possible mechanisms. EC-specific aspartic aminotransferase 1 transgenic (EC-AAT1-Tg) mice were constructed in vivo. Pulmonary hypertension was induced by hypoxia. Right heart catheterization and echocardiography were used to detect mouse hemodynamic changes. Pathologic analysis was performed in the pulmonary arteries. High-performance liquid chromatography was employed to detect the SO2 content. Human PAECs (HPAECs) with lentiviruses containing AAT1 cDNA or shRNA and cocultured human PASMCs (HPASMCs) were applied in vitro. SO2 probe and enzyme-linked immunosorbent assay were used to detect the SO2 content and determine p50 activity, respectively. Hypoxia caused a significant reduction in SO2 content in the mouse lung and HPAECs and increases in right ventricular systolic pressure, pulmonary artery wall thickness, muscularization, and the expression of PAEC ICAM-1 and MCP-1 and of PASMC Ki-67, collagen I, and α-SMA (p < 0.05). However, EC-AAT1-Tg with sufficient SO2 content prevented the above increases induced by hypoxia (p < 0.05). Mechanistically, EC-derived SO2 deficiency promoted HPAEC ICAM-1 and MCP-1 and the cocultured HPASMC Ki-67 and collagen I expression, which was abolished by andrographolide, an inhibitor of p50 (p < 0.05). Meanwhile, EC-derived SO2 deficiency increased the expression of cocultured HPASMC α-SMA (p < 0.05). Taken together, these findings revealed that EC-derived SO2 inhibited p50 activation to control PAEC inflammation in an autocrine manner and PASMC proliferation, hypertrophy, and collagen synthesis in a paracrine manner, thereby inhibiting hypoxic PVR.

Significance of the ability to differentiate emotional prosodies for the early diagnosis and prognostic prediction of mild hypoxic-ischemic encephalopathy in neonates.

BACKGROUND: Perinatal brain injury affects around 300,000 neonates in China each year, early diagnosis and active intervention are also crucial for timely treatment and better prognoses. As hearing is the earliest as well as the most sensitive sense to develop in neonates, we propose that the ability to differentiate among different emotional prosodies may differ between neonates with and without brain injuries. METHODS: We enrolled full-term neonates admitted to the neonatology department of Peking University First Hospital from January 2016 to December 2016, conducted functional near-infrared spectroscopy (fNIRS) monitoring within 24 hr of admission, and analyzed changes in oxyhemoglobin (ΔHbO2 ) and deoxyhemoglobin (ΔHb) to study the ability of neonates to differentiate among emotional prosodies. The neonates were followed up to 36 months for neurological outcome evaluation. RESULTS AND CONCLUSIONS: We found that neonates showed the early ability to differentiate among emotional prosodies, responding most sensitively to positive emotions, and this ability may have been impaired following brain injury.

Increased Endogenous Sulfur Dioxide Involved in the Pathogenesis of Postural Tachycardia Syndrome in Children: A Case-Control Study.

BACKGROUND: The pathogenesis of postural tachycardia syndrome (POTS) remains unclear. This study aimed to explore the changes and significance of sulfur dioxide (SO2) in patients with POTS. METHODS: The study included 31 children with POTS and 27 healthy children from Peking University First Hospital between December 2013 and October 2015. A detailed medical history, physical examination results, and demographic characteristics were collected. Hemodynamics was recorded and the plasma SO2was determined. RESULTS: The plasma SO2was significantly higher in POTS children compared to healthy children (64.0 ± 20.8 µmol/L vs. 27.2 ± 9.6 µmol/L, respectively, P < 0.05). The symptom scores in POTS were positively correlated with plasma SO2levels (r = 0.398, P < 0.05). In all the study participants, the maximum heart rate (HR) was positively correlated with plasma levels of SO2(r = 0.679, P < 0.01). The change in systolic blood pressure from the supine to upright (ΔSBP) in POTS group was smaller than that in the control group (P < 0.05). The ΔSBP was negatively correlated with baseline plasma SO2levels in all participants (r = -0.28, P < 0.05). In the control group, ΔSBP was positively correlated with the plasma levels of SO2(r = 0.487, P < 0.01). The change in HR from the supine to upright in POTS was obvious compared to that of the control group. The area under curve was 0.967 (95% confidence interval: 0.928-1.000), and the cutoff value of plasma SO2 level >38.17 µmol/L yielded a sensitivity of 90.3% and a specificity of 92.6% for predicting the diagnosis of POTS. CONCLUSIONS: Increased endogenous SO2levels might be involved in the pathogenesis of POTS.

Endogenous Hydrogen Sulfide Enhances Carotid Sinus Baroreceptor Sensitivity by Activating the Transient Receptor Potential Cation Channel Subfamily V Member 1 (TRPV1) Channel.

BACKGROUND: We aimed to investigate the regulatory effects of hydrogen sulfide (H2S) on carotid sinus baroreceptor sensitivity and its mechanisms. METHODS AND RESULTS: Male Wistar-Kyoto rats and spontaneously hypertensive rats (SHRs) were used in the experiment and were given an H2S donor or a cystathionine-ß-synthase inhibitor, hydroxylamine, for 8 weeks. Systolic blood pressure and the cystathionine-ß-synthase/H2S pathway in carotid sinus were detected. Carotid sinus baroreceptor sensitivity and the functional curve of the carotid baroreceptor were analyzed using the isolated carotid sinus perfusion technique. Effects of H2S on transient receptor potential cation channel subfamily V member 1 (TRPV1) expression and S-sulfhydration were detected. In SHRs, systolic blood pressure was markedly increased, but the cystathionine-ß-synthase/H2S pathway in the carotid sinus was downregulated in comparison to that of Wistar-Kyoto rats. Carotid sinus baroreceptor sensitivity in SHRs was reduced, demonstrated by the right and upward shift of the functional curve of the carotid baroreceptor. Meanwhile, the downregulation of TRPV1 protein was demonstrated in the carotid sinus; however, H2S reduced systolic blood pressure but enhanced carotid sinus baroreceptor sensitivity in SHRs, along with TRPV1 upregulation in the carotid sinus. In contrast, hydroxylamine significantly increased the systolic blood pressure of Wistar-Kyoto rats, along with decreased carotid sinus baroreceptor sensitivity and reduced TRPV1 protein expression in the carotid sinus. Furthermore, H2S-induced enhancement of carotid sinus baroreceptor sensitivity of SHRs could be amplified by capsaicin but reduced by capsazepine. Moreover, H2S facilitated S-sulfhydration of TRPV1 protein in the carotid sinus of SHRs and Wistar-Kyoto rats. CONCLUSIONS: H2S regulated blood pressure via an increase in TRPV1 protein expression and its activity to enhance carotid sinus baroreceptor sensitivity.

Baroreflex Sensitivity Predicts Short-Term Outcome of Postural Tachycardia Syndrome in Children.

OBJECTIVE: The study was designed to examine if baroreflex sensitivity (BRS) could predict the short-term outcome of postural tachycardia syndrome (POTS) in children. METHODS: Seventy-seven children subjects were included in the study. Among them, 45 children were in the POTS group and another 32 healthy children were in the control group. A ninety-day clinical follow-up was conducted and the symptom score before and after the follow-up was calculated for POTS patients by using POTS score system. Hemodynamics and continuous BRS monitoring were recorded by Finapres Medical System-FMS (FinometerPRO, FMS Company, Netherlands). According to the symptom score change during follow-up period, POTS patients were further divided into subgroup A (n = 24) with symptom score decreased by at least two points and subgroup B (n = 21) with symptom score decreased by less than two points. The predictive value of BRS in the short-term outcome of POTS in children was analyzed using receiver-operating characteristic (ROC) curve. RESULTS: BRS of POTS children was significantly higher than that of the healthy children (18.76±9.96 ms/mmHg vs 10±5.42 ms/mmHg, P<0.01). It was higher in subgroup B than that of subgroup A (24.7±9.9 ms/mmHg vs 13.5±6.6 ms/mmHg, P <0.01). BRS was positively correlated with HR change in POTS Group (r = 0.304, P <0.05). Area under curve (AUC) was 0.855 (95% of confidence interval 0.735-0.975), and BRS of 17.01 ms/mmHg as a cut-off value yielded the predictive sensitivity of 85.7% and specificity of 87.5%. CONCLUSIONS: BRS is a useful index to predict the short-term outcome of POTS in children.

Value of the Ratio of Occluder Versus Atrial Septal Length for Predicting Arrhythmia Occurrence after Transcatheter Closure in Children with Ostium Secundum Atrial Septal Defect.

BACKGROUND: Transcatheter occlusion has been applied to treat ostium secundum atrial septal defect (OS ASD) since 1997. During the clinical practice, several postoperative complications including arrhythmia have been reported. This study aimed to evaluate the value of the ratio of atrial septal occluder (ASO) versus atrial septal length (ASL) for predicting arrhythmia occurrence after transcatheter closure in children with OS ASD. METHODS: Six hundred and fifty-one children diagnosed with OS ASD underwent occlusion procedures after completing routine examinations. The onsets and types of arrhythmia both during and after the occlusion procedures were monitored. Treatments were given based on the individual types of arrhythmia. The binary logistic regression analysis and receiver-operating characteristic (ROC) curve were used in the analysis of value of the ratio of ASO/ASL for predicting postoperative arrhythmia occurrence. RESULTS: Transcather occlusions were conducted in 651 children, among whom 7 children had different types and degrees of arrhythmia, with an incidence of 1.1%. The types of arrhythmia included sinus bradycardia, atrial premature beats, bundle branch block, and different degrees of atrioventricular block. Normal electrocardiograph findings were resumed in these 7 patients following active therapies such as corticoids, nutrition, and surgeries. The binary logistic regression and ROC analysis suggested that the ratio of ASO/ASL exhibited an intermediate predictive value for predicting arrhythmia occurrence after occlusion procedures. A cut-off value of 0.576 in the ratio provided a sensitivity of 87.5% and a specificity of 76.2% with an area under the ROC curve of 0.791 (95% confidence intervals, 0.655-0.926; P < 0.05) in predicting arrhythmia occurrence after the closure procedures. CONCLUSIONS: The ratio of ASO/ASL might be a useful index for predicting arrhythmia occurrence after closure procedures in children with OS ASD.

Two congenital coronary abnormalities affecting heart function: anomalous origin of the left coronary artery from the pulmonary artery and congenital left main coronary artery atresia.

BACKGROUND: The anomalous origin of the left coronary artery (LCA) from the pulmonary artery (ALCAPA) and congenital left main coronary artery atresia (CLMCA-A) are two kinds of very rare coronary heart diseases which affect heart function profoundly. This study aimed to retrospectively illustrate the clinical features and therapy experience of ALCAPA and CLMCA-A patients. METHODS: From April 1984 to July 2012, in Beijing Anzhen Hospital, 23 patients were diagnosed with ALCAPA and 4 patients with CLMCA-A. We summarized the clinical data of the 27 cases and retrospectively analyzed the clinical manifestation, diagnosis, and treatments of these two kinds of congenital coronary abnormalities. RESULTS: The 23 patients (13 males and 10 females, aged ranging from 2.5 months to 65 years) identified with ALCAPA were classified into infantile type (age of onset younger than 12 months, 16 cases) and adult type (age of onset older than 12 months, 7 cases). Four patients were diagnosed with CLMCA-A (three males and one female, aged ranging from 3 months to 2 years). The main clinical manifestations of infantile-type ALCAPA and CLMCA-A include repeated respiratory tract infection, heart failure, dyspnea, feeding intolerance, diaphoresis, and failure to thrive. And these two congenital coronary abnormalities might be misdiagnosed as endocardial fibroelastosis, dilated cardiomyopathy, and acute myocardial infarction. As for the adult-type ALCAPA, cardiac murmurs and discomfort of the precordial area are the most common presentations and might be misdiagnosed as coronary heart disease, myocarditis, or patent ductus arteriosus. In ECG examination: Infantile-type ALCAPA and CLMCA-A showed abnormal Q waves with T wave inversion in leads I, avL, and V4-V6, especially in lead avL. However, ECG of adult-type ALCAPA lacked distinct features. In chest radiography: pulmonary congestion and cardiomegaly were the most common findings in infantile-type ALCAPA and CLMCA-A, while pulmonary artery segment dilation was more common in adult type. In echocardiography, the common features of infantile-type ALCAPA and CLMCA-A included left ventricular enlargement, left ventricular systolic function normal or mildly reduced in CLMCA-A or significantly reduced in ALCAPA, and moderate to large mitral valve. It was performed in 9 of 23 cases of ALCAPA and showed the origin of the dilated right coronary artery (RCA) from the right sinus of the aortic root and absence of LCA origin in angiography. After opacification of RCA, reverse flow in the LCA and pulmonary artery was visualized through coronary artery collateral circulation. Angio was performed in three of the four cases of CLMCA-A and showed left main coronary artery was a blind end, with diameter of only 1.1-2.0 mm. Treatment and prognosis: 21 patients with ALCAPA had cardiac surgery and 6 of them died postoperatively. Fifteen postoperative patients survived without overt symptoms within the follow-up period of 6-166 months (median 17 months). As for treatment of CLMCA-A, four patients took digoxin and diuretics without undergoing cardiac surgery. Their clinical symptoms improved during the close follow-ups. CONCLUSIONS: ALCAPA and CLMCA-A are two rare coronary artery abnormalities that affect cardiac function in infants and children. In younger patients with cardiomegaly and heart dysfunction these two congenital coronary diseases should be noticed.