Expanding the Reactive Sulfur Metabolome: Intracellular and Efflux Measurements of Small Oxoacids of Sulfur (SOS) and H2S in Human Primary Vascular Cell Culture

Hydrogen sulfide (H2S) is an endogenous signaling molecule which is important for cardiovascular health, but its mechanism of action remains poorly understood. Here, we report measurements of H2S as well as its oxidized metabolites, termed small oxoacids of sulfur (SOS = HSOH and HOSOH), in four human primary vascular cell lines: smooth muscle and endothelial cells derived from both human arterial and coronary tissues. We use a methodology that targets small molecular weight sulfur species; mass spectrometric analysis allows for species quantification to report cellular concentrations based on an H2S calibration curve. The production of H2S and SOS is orders of magnitude higher in smooth muscle (nanomolar) as compared to endothelial cell lines (picomolar). In all the primary lines measured, the distributions of these three species were HOSOH >H2S > HSOH, with much higher SOS than seen previously in non-vascular cell lines. H2S and SOS were effluxed from smooth muscle cells in higher concentrations than endothelial cells. Aortic smooth muscle cells were used to examine changes under hypoxic growth conditions. Hypoxia caused notable increases in HSOH and ROS, which we attribute to enhanced sulfide quinone oxidase activity that results in reverse electron transport.

Characterization of Endogenous and Extruded H2S and Small Oxoacids of Sulfur (SOS) in Cell Cultures

This report characterizes and quantifies endogenous hydrogen sulfide (H₂S) and small oxoacids of sulfur (SOS = HOSH, HOSOH) in a panel of cell lines including human cancer (A375 melanoma cells, HeLa cervical cells) and noncancer (HEK293 embryonic kidney cells), as well as E. coli DH5α and S. cerevisiae S288C. The methodology used is a translation of well-studied nucleophilic and electrophilic traps for cysteine and oxidized cysteines residues to target small molecular weight sulfur species; mass spectrometric analysis allows for species quantification. The observed intracellular concentrations of H₂S and SOS vary in different cell types, from nanomolar to femtomolar, typically with H₂S > HOSOH > HOSH. We propose the term sulfome, a subset of the metabolome, describing the nonproteinaceous metabolites of H₂S; the sulfomic index is as a measure of the S-oxide redox status, which gives a profile of endogenous sulfur at different oxidation states. An important observation is that H₂S and SOS were found to be continuously extruded into surrounding media against a concentration gradient, implying an active efflux process. Small molecule inhibition of several H₂S generating enzymes suggest that SOS are not derived solely from H₂S oxidation. Even after successful inhibition of H₂S production, cells maintain constant efflux and repopulate H₂S and SOS over time. This work proves that these small sulfur oxoacids are generated in cells of all types, and their efflux implies that they play a role in cell signaling and possibly other vascular physiology attributed to H₂S.

Chemical trapping and characterization of small oxoacids of sulfur (SOS) generated in aqueous oxidations of H2S

Small oxoacids of sulfur (SOS) are elusive molecules like sulfenic acid, HSOH, and sulfinic acid, HS(O)OH, generated during the oxidation of hydrogen sulfide, H2S, in aqueous solution. Unlike their alkyl homologs, there is a little data on their generation and speciation during H2S oxidation. These SOS may exhibit both nucleophilic and electrophilic reactivity, which we attribute to interconversion between S(II) and S(IV) tautomers. We find that SOS may be trapped in situ by derivatization with nucleophilic and electrophilic trapping agents and then characterized by high resolution LC MS. In this report, we compare SOS formation from H2S oxidation by a variety of biologically relevant oxidants. These SOS appear relatively long lived in aqueous solution, and thus may be involved in the observed physiological effects of H2S.

Mechanistic Investigations of Photoinduced Oxygenation of Ru(II) Bis-bipyridyl Flavonolate Complexes

We previously reported that a Ru-bound flavonolate model of flavonol dioxygenases, [Ru^II(bpy)₂(3-hydroxyfla)][PF₆], photochemically reacts with dioxygen in two different manners. Broad-band excitation generates mixtures of products characteristic of 1,3-addition of dioxygen across the central pyrone ring, as is observed in enzymatic reactions. However, low temperature excitation at wavelengths longer than 400 nm generates a unique Ru-bound 2-benzoatophenylglyoxylate product resulting from a 1,2-dioxetane intermediate. Herein, we investigate this reactivity in a series of Ru(II)bis-bipyridyl flavonolate complexes [Ru^II(bpy)₂(3-hydroxyfla^R)][PF₆] (bpy = 2,2'-bipyridine; fla = flavonolate; R = p-OMe (1), p-Me (2), p-H (3), p-Cl (4)), and [Ru^II(bpy)₂(5-hydroxyfla)][PF₆] (5). The complexes' structures, photophysical and electrochemical properties, and photochemical reactivity with oxygen were investigated in detail. Two different reaction product mixtures, from 1,2- and 1,3-additions of dioxygen, are observed by illumination into distinct excitation/emission manifolds. By analogy to previous reports of excited state intramolecular proton transfer, the two manifolds are attributed to tautomeric diradicals that predict the observed reactivity patterns.

Influence of age on arsenic-induced behavioral and cholinergic perturbations: Amelioration with zinc and α-tocopherol

This study was planned to determine arsenic (As) (10 mg/kg body weight given through oral gavage) induced behavioral and cholinergic perturbations in three different age groups of rats; young (postnatal day 21), adult (3 months), and aged (18 months) at 7 days post-acute exposure ( n = 6 for each of the four groups of all three age points). Further, we also evaluated the ameliorative effect of essential metal zinc (Zn; 0.02% through drinking water) and an antioxidant, α-tocopherol (vitamin E; 125 mg/kg body weight through oral gavage) against As-induced neurotoxicity. As exposure showed significant alterations in behavioral functions (open-field behavior, total locomotor activity, grip strength, exploratory behavior, and water maze learning). Cholinergic studies in three brain regions (cerebral cortex, cerebellum, and hippocampus) of different age groups also showed significant increase in acetylcholine levels and a decrease in acetylcholinesterase activity. These effects were more pronounced in hippocampus followed by cerebral cortex and cerebellum. Among the three different age points, aged animals were found to be more vulnerable to the As-induced toxicity as compared to young and adult animals suggesting that As neurotoxicity is age dependent. These As-induced alterations were significantly reversed following supplementation with Zn or vitamin E. However, vitamin E was found to elicit greater protection as compared to Zn in restoring the altered behavioral and cholinergic perturbations, providing evidence for As-induced oxidative damage.

Trapping Reactions of the Sulfenyl and Sulfinyl Tautomers of Sulfenic Acids

Sulfenic acids react as both nucleophiles and electrophiles, which may be attributable to interconversion between sulfenyl and sulfinyl tautomers. We demonstrate one-pot trapping of both tautomeric forms of glutathione sulfenic acid by LCMS. The sulfinyl tautomers are characterized by reaction with nucleophilic reagents such as dimedone and cyanide, giving unique products that are analogous to corresponding adducts of aldehydes. Likewise, we show that aldehyde reactive reagents such as silyl enol ethers also react with glutathione sulfenic acid to give products characteristic of both sulfenyl and sulfinyl tautomers.

Risk factors associated with death among influenza A (H1N1) patients, Tamil Nadu, India, 2010

BACKGROUND

Limited information is available about the risk factors associated with death among patients of influenza A (H1N1) in India.

AIMS

To describe the epidemiology of laboratory-confirmed influenza A (H1N1) patients and identify risk factors associated with death.

SETTINGS AND DESIGN

We reviewed the surveillance data of laboratory-confirmed patients in Tamil Nadu, India, for the year 2010. We conducted a case-control study by comparing 70 laboratory-confirmed A (H1N1) patients who died (cases) with 210 A (H1N1) patients who recovered (controls) to identify the risk factors for deaths.

MATERIALS AND METHODS

We interviewed the controls and immediate care-takers of the influenza patients who died to collect information about socio-demographic details and co-morbid conditions. We used an abstraction form to collect the information about the clinical details from the case records of the hospitals where the cases and controls received treatment.

STATISTICAL ANALYSIS

We analysed the surveillance data by time, place and person. We conducted univariate and multivariate logistic regression analysis for identifying factors associated death.

RESULTS

During 2010, 1302 laboratory-confirmed cases were reported to the Tamil Nadu surveillance unit. Of these, 72 patients died (case fatality=5.5%). About 2/3 of the cases and 40% of the deaths were from three districts. On multivariate analysis, past history of diabetes, treatment in private hospitals, treatment with corticosteroids during illness, visit to >1 healthcare facility before laboratory confirmation and delay of >48 h in starting antivirals were found to be independently associated with the deaths.

CONCLUSIONS

Influenza patients with previous history of diabetes, who had treatment with corticosteroids during illness, and started with antivirals after 48 h of onset of symptoms, were at higher risk of adverse outcome. In order to reduce the risk of death during future waves of influenza in Tamil Nadu, the physicians need to be sensitised regarding (1) higher risk of adverse outcomes among A (H1N1) patients with diabetes; (2) adherence to the national protocol for categorisation of cases; (3) prompt initiation of antivirals for severe cases; and (4) avoidance of systemic corticosteroids during management.

A singular value decomposition approach for kinetic analysis of reactions of HNO with myoglobin

The reactions of several horse heart myoglobin species with nitrosyl hydride, HNO, derived from Angeli's salt (AS) and Piloty's acid (PA) have been followed by UV-visible, (1)H NMR and EPR spectroscopies. Spectral analysis of myoglobin-derived speciation during the reactions was obtained by using singular value decomposition methods combined with a global analysis to obtain the rate constants of complex sequential reactions. The analysis also provided spectra for the derived absorbers, which allowed self-consistent calibration to the spectra of known myoglobin species. Using this method, the determined rate for trapping of HNO by metmyoglobin, which produces NO-myoglobin, is found to be 2.7 × 10(5)M(-1)s(-1) at pH7.0 and 1.1 × 10(5)M(-1)s(-1) at pH9.4. The reaction of deoxymyoglobin with HNO generates the adduct HNO-myoglobin directly, but is followed by a secondary reaction of that product with HNO yielding NO-myoglobin; the determined bimolecular rate constants for these reactions are 3.7 × 10(5)M(-1)s(-1) and 1.67 × 10(4)M(-1)s(-1) respectively, and are independent of pH. The derived spectrum for HNO-myoglobin is characterized by a Soret absorbance maximum at 423 nm with an extinction coefficient of 1.66 × 10(5)M(-1)cm(-1). The rate constant for unimolecular loss of HNO from HNO-myoglobin was determined by competitive trapping with CO at 8.9 × 10(-5)s(-1), which gives the thermodynamic binding affinity of HNO to deoxymyoglobin as 4.2 × 10(9)M(-1). These results suggest that the formation of HNO-ferrous heme protein adducts represents an important consideration in the biological action of HNO-releasing drugs.

Protective effects of gallic acid on hepatic lipid peroxide metabolism, glycoprotein components and lipids in streptozotocin-induced type II diabetic Wistar rats

We evaluated the protective effects of gallic acid (3,4,5-trihydroxybenzoic acid) on hepatic lipid peroxidation products, antioxidants, glycoprotein components, and lipids in streptozotocin-induced type II diabetic rats. To induce type II diabetes, rats were injected with streptozotocin intraperitoneally at a single dose of 40 mg/kg. Gallic acid (10 and 20 mg/kg) treatment was given to diabetic rats orally using an intragastric tube daily for 21 days. Streptozotocin-induced diabetic rats showed a significant increase in the levels of blood glucose, hepatic lipid peroxidation products, glycoprotein components, lipids, and the activity of HMG-CoA reductase and a significant decrease in the levels of plasma insulin and liver glycogen. In addition to this, the activities/levels of hepatic antioxidants were decreased in diabetic rats. Gallic acid (10 and 20 mg/kg) treatment showed significant protective effects on all the biochemical parameters studied in diabetic rats. Thus, our study shows the antihyperglycemic, antilipid peroxidative, antioxidant, and antilipidemic effects of gallic acid in streptozotocin-induced type II diabetic rats. A diet containing gallic acid may be beneficial to type II diabetic patients.

Reactions of HNO with heme proteins: new routes to HNO-heme complexes and insight into physiological effects

The formation and interconversion of nitrogen oxides has been of interest in numerous contexts for decades. Early studies focused on gas-phase reactions, particularly with regard to industrial and atmospheric environments, and on nitrogen fixation. Additionally, investigation of the coordination chemistry of nitric oxide (NO) with hemoglobin dates back nearly a century. With the discovery in the early 1980s that NO is biosynthesized as a molecular signaling agent, the literature has been focused on the biological effects of nitrogen oxides, but the original concerns remain relevant. For instance, hemoglobin has long been known to react with nitrite, but this reductase activity has recently been considered to be important to produce NO under hypoxic conditions. The association of nitrosyl hydride (HNO; also commonly referred to as nitroxyl) with heme proteins can also produce NO by reductive nitrosylation. Furthermore, HNO is considered to be an intermediate in bacterial denitrification, but conclusive identification has been elusive. The authors of this article have approached the bioinorganic chemistry of HNO from different perspectives, which have converged because heme proteins are important biological targets of HNO.

Nitrosyl hydride (HNO) as an O2 analogue: long-lived HNO adducts of ferrous globins

Nitrosyl hydride, HNO or nitroxyl, is the one-electron reduced and protonated form of nitric oxide. HNO is isoelectronic to singlet O(2), and we have previously reported that deoxymyoglobin traps free HNO to form a stable adduct. In this report, we demonstrate that oxygen-binding hemoglobins from human, soy, and clam also trap HNO to form adducts which are stable over a period of weeks. The same species can be formed in higher yields by careful reduction of the ferrous nitrosyl adducts of the proteins. Like the analogous O(2)-Fe(II) adducts, the HNO adducts are diamagnetic, but with a characteristic HNO resonance in (1)H NMR at ca. 15 ppm that splits into doublets for H(15)NO adducts. The (1)H and (15)N NMR resonances, obtained by HSQC experiments, are shown to differentiate subunits and isoforms of proteins within mixtures. An apparent difference in the reduction rates of the NO adducts of the two subunits of human hemoglobin allows assignment of two distinct nitrosyl hydride peaks by a combination of UV-vis, NMR, and EPR analysis. The two peaks of the HNO-hHb adduct have a persistent 3:1 ratio during trapping reactions, demonstrating a kinetic difference between HNO binding at the two subunits. These results show NMR characterization of ferrous HNO adducts as a unique tool sensitive to structural changes within the oxygen-binding cavity, which may be of use in defining modes of oxygen binding in other heme proteins and enzymes.

Multiple arterial variations in the upper limb of a South Indian female cadaver

In a routine dissection of a female cadaver, a variation in the course of the radial artery in the cubital fossa and a communication between the brachial artery and radial artery were observed. A rare origin and course of the median artery was also found. These anomalies are discussed in detail and their clinical relevance is highlighted.

Randomised trial of intrapleural urokinase in the treatment of childhood empyema

BACKGROUND

The role of intrapleural fibrinolytic agents in the treatment of childhood empyema has not been established. A randomised double blind placebo controlled trial of intrapleural urokinase was performed in children with parapneumonic empyema.

METHODS

Sixty children (median age 3.3 years) were recruited from 10 centres and randomised to receive either intrapleural urokinase 40 000 units in 40 ml or saline 12 hourly for 3 days. The primary outcome measure was length of hospital stay after entry to the trial.

RESULTS

Treatment with urokinase resulted in a significantly shorter hospital stay (7.4 v 9.5 days; ratio of geometric means 1.28, CI 1.16 to 1.41 p=0.027). A post hoc analysis showed that the use of small percutaneous drains was also associated with shorter hospital stay. Children treated with a combination of urokinase and a small drain had the shortest stay (6.0 days, CI 4.6 to 7.8).

CONCLUSION

Intrapleural urokinase is effective in treating empyema in children and significantly shortens hospital stay.

Near drowning in cold water

Drowning and near drowning is a common cause of accidental death all over the world; specially in road traffic accidents over bridges, swimming pool and boat tragedies. Cold water drowning resulting in hypothermia can lead to instant death before actual drowning. Five cases of near drowning (ND) in cold water, who presented with varied clinical picture like coma with decerebrate rigidity and fixed dilated pupils, hypertension with coma and delayed pulmonary oedema (Secondary drowning) are reported. Energetic management with continuous positive airway pressure was very rewarding in all patients with ND except in one who had transient organic psychosis persisting for two weeks followed by minimal cognitive defect in the form of slow mentation, lack of drive and mild irritability (Bender Gestald Test Score of 53). We have tried to analyse some of the clinical features of ND and the sequel associated with it. The management as well as recent developments in the field are also discussed.

Near drowning in cold water

Drowning and near drowning is a common cause of accidental death all over the world; specially in road traffic accidents over bridges, swimming pool and boat tragedies. Cold water drowning resulting in hypothermia can lead to instant death before actual drowning. Five cases of near drowning (ND) in cold water, who presented with varied clinical picture like coma with decerebrate rigidity and fixed dilated pupils, hypertension with coma and delayed pulmonary oedema (Secondary drowning) are reported. Energetic management with continuous positive airway pressure was very rewarding in all patients with ND except in one who had transient organic psychosis persisting for two weeks followed by minimal cognitive defect in the form of slow mentation, lack of drive and mild irritability (Bender Gestald Test Score of 53). We have tried to analyse some of the clinical features of ND and the sequel associated with it. The management as well as recent developments in the field are also discussed.

Phosphate radical induced oxidation of pyrimidine bases in aqueous solution

The photooxidation of pyrimidine bases viz., uracil and cytosine in presence of peroxydiphosphate (PDP) in aqueous solution at natural pH (approximately 7.5) has been carried out in a quantum yield reactor using a high-pressure mercury lamp. The rates of oxidation and quantum yields of pyrimidine oxidation have been found to increase with increase in [PDP] while they are independent of [pyrimidine] and light intensity. On the basis of these experimental results, product analysis and existence of isosbestic points a probable mechanism is suggested in which peroxydiphosphate ion on photolysis gives phosphate radical anions which initiates the reaction by adding to C(5) or C(6) of pyrimidine base leading to the formation of pyrimidine radical via radical cation or hydrolysis. This further reacts with PDP and gives the final products 5,6-dihydroxy pyrimidine and isobarbituric acid.

Antinociceptive and anti-inflammatory activity of carumbelloside-I isolated from Caralluma umbellata

The phytochemical study using Caralluma umbellata (Asclepiadaceae) whole plant allowed the isolation of a novel pregnane glycoside named carumbelloside-I (3-O-beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranosyl-3beta,14beta -dihydroxypregn-5-en-20-one). Carumbelloside-I was evaluated for both antinociceptive activity and anti-inflammatory activity. The antinociceptive activity was evaluated in mice using the writhing test method, while the anti-inflammatory activity was evaluated in rats using the paw edema test with carrageenin. Carumbelloside-I has significant antinociceptive action. It has no anti-inflammatory activity.

Significance of lymphocytic sister chromatid exchange frequencies in ovarian cancer patients

Very few studies report the analysis of sister chromatid exchanges in ovarian cancer patients. We tested the null hypothesis that SCE frequency increases with the advancing stages of ovarian cancer and follows a Poisson distribution. As controls we examined age- and sex-matched healthy volunteers who had no such past history. An increased average SCE frequency was observed in ovarian cancer patients (6.34 +/- 0.09) vis-à-vis controls (4.47 +/- 0.12). Further, the data also suggested a stage-wise increase in the SCE frequency.

Perinatal mortality trends in a referral hospital

A comparative study of perinatal mortality patterns over a period was conducted at a teaching hospital of South India. Among the 6,048 babies born from January 1984 to December 1985 (Group A), there were 265 (43.8/1000) still births and 127 (22.0/1000) early neonatal deaths. Three hundred and thirty seven (41/1000) babies were still born and 235 (29.8/1000) early neonatal deaths out of 8,215 deliveries during 1992-93 (Group B). The perinatal mortality rate (PMR) in Groups A and B were 57.9/1000 and 57.7/1000 respectively. Unbooked cases accounted for the majority (> 75%) of perinatal deaths during both the periods. The overall mortality rates in unbooked cases were three to four times higher than booked cases. Among the various causes of still births, antepartum haemorrhage and uterine rupture had increased. Septicaemia was the major cause of early neonatal deaths in Group A, but in Group B birth asphyxia and prematurity were the leading causes. Effective interventions like creating awareness among the target population to utilise maternal and child health services and early referral of high risk cases with improved intranatal and perinatal care can decrease the perinatal mortality.

A rapid silver staining and destaining technique for the nucleolus organizer region

Silver staining of nucleolar organizing regions (NOR) is common, but a standard protocol is lacking. A modification of a rapid silver nitrate staining technique for NORs is presented here. Advantages of the modified technique include reliability, speed, cost and the fact that it can be carried out in the light.

Anacardoside from the seeds of Semecarpus anacardium

From the seeds of Semecarpus anacardium, a new phenolic glucoside, anacardoside, was isolated, and its structure and configuration were elucidated by a combination of NMR techniques as 1-O-beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranosyloxy-3-hydro xy-5-methylbenzene.

Resonance assignment of the 500-MHz proton NMR spectrum of self-complementary dodecanucleotide d-GGATCCGGATCC: altered conformations at BamHI cleavage sites

Resonance assignments of nonexchangeable base and sugar protons of the self-complementary dodecanucleotide d-GGATCCGGATCC have been obtained by two-dimensional NMR methods and strategies derived from interproton distance calculations on different secondary structures of nucleic acids. Conformational details about the glycosidic dihedral angle and sugar pucker have been derived from the relative intensities of cross peaks in the two-dimensional J-correlated and nuclear Overhauser enhancement correlated spectra in D2O solution. It is observed that d-GGATCCGGATCC assumes a predominantly B-type conformation with sequence-dependent changes along the chain. The recognition site of BamHI shows a distinctly different geometrical environment. The sugar rings of G1 and G7 assume a C3'-endo geometry while the rest of the sugars possess C2'-endo geometry.

Nutritional management of the cardiac transplant patient

Cardiac transplantation, along with successful immunosuppressive therapy, is emerging as a reasonable therapeutic procedure for prolonging the life of patients with end-stage coronary artery disease. Nutritional management is an important factor in total patient care. Dietary principles as outlined here are intended to serve as nutrition guidelines rather than dietary restrictions. The primary goal is to promote sound nutritional health without aggravating the metabolic consequences of immunosuppressive therapy.