Moore PK. Hydrogen sulfide and its possible roles in myocardial ischemia in experimental rats. J Appl Physiol 102: [261][262][263][264][265][266][267][268] 2007. First published October 12, 2006; doi:10.1152/japplphysiol.00096.2006.-The role of hydrogen sulfide (H 2S) in myocardial infarction (MI) has not been previously studied. We therefore investigated the effect of H 2S in a rat model of MI in vivo. Animals were randomly divided into three groups (n ϭ 80) and received either vehicle, 14 mol/kg of sodium hydrosulfide (NaHS), or 50 mg/kg propargylglycine (PAG) everyday for 1 wk before surgery, and the treatment was continued for a further 2 days after MI when the animals were killed. The mortality was 35% in vehicletreated, 40% in PAG-treated, and 27.5% in NaHS-treated (P Ͻ 0.05 vs. vehicle) groups. Infarct size was 52.9 Ϯ 3.5% in vehicle-treated, 62.9 Ϯ 7.6% in PAG-treated, and 43.4 Ϯ 2.8% in NaHS-treated (P Ͻ 0.05 vs. vehicle) groups. Plasma H 2S concentration was significantly increased after MI (59.2 Ϯ 7.16 M) compared with the baseline concentration (i.e., 38.2 Ϯ 2.07 M before MI; P Ͻ 0.05). Elevated plasma H 2S after MI was abolished by treatment of animals with PAG (39.2 Ϯ 5.02 M). We further showed for the first time cystathioninegamma-lyase protein localization in the myocardium of the infarct area by using immunohistochemical staining. In the hypoxic vascular smooth muscle cells, we found that cell death was increased under the stimuli of hypoxia but that the increased cell death was attenuated by the pretreatment of NaHS (71 Ϯ 1.2% cell viability in hypoxic vehicle vs. 95 Ϯ 2.3% in nonhypoxic control; P Ͻ 0.05). In conclusion, endogenous H 2 S was cardioprotective in the rat model of MI. PAG reduced endogenous H 2S production after MI by inhibiting cystathionine-gamma-lyase. The results suggest that H 2S might provide a novel approach to the treatment of MI.cardioprotection; gasomediator; cardiac protection; ischemic animal model FOR MANY YEARS, HYDROGEN SULFIDE (H 2 S) has been considered solely as a broad-spectrum environmental toxicant with effects on many major organ systems, including the lung, brain, and kidney (2, 11). However, the possible physiological role(s) of H 2 S in the cardiovascular system have only recently come to light. It has been suggested that H 2 S interferes with cardiovascular function as a result of anoxia rather than a direct action on cardiac myocytes or vascular smooth muscle cells (13). However, this possibility now appears less certain in light of more recent research. The localization of H 2 S-generating enzymes and the detection of biologically significant levels of H 2 S in plasma and tissue homogenate from animals have recently been reported (20). Endogenous H 2 S is formed locally by the activity of two pyridoxal-5Ј-phosphate-dependent enzymes, namely cystathionine ␤-synthase and cystathionine ␥-lyase (CSE), each of which utilize L-cysteine as substrate (17). Although cystathionine ␤-synthase does not appear to play a major role in generating H 2 S in cardiovasc...

Herbs are often administered in combination with therapeutic drugs, raising the potential of herb-drug interactions. An extensive review of the literature identified reported herb-drug interactions with clinical significance, many of which are from case reports and limited clinical observations. Cases have been published reporting enhanced anticoagulation and bleeding when patients on long-term warfarin therapy also took Salvia miltiorrhiza (danshen). Allium sativum (garlic) decreased the area under the plasma concentration-time curve (AUC) and maximum plasma concentration of saquinavir, but not ritonavir and paracetamol (acetaminophen), in volunteers. A. sativum increased the clotting time and international normalised ratio of warfarin and caused hypoglycaemia when taken with chlorpropamide. Ginkgo biloba (ginkgo) caused bleeding when combined with warfarin or aspirin (acetylsalicylic acid), raised blood pressure when combined with a thiazide diuretic and even caused coma when combined with trazodone in patients. Panax ginseng (ginseng) reduced the blood concentrations of alcohol (ethanol) and warfarin, and induced mania when used concomitantly with phenelzine, but ginseng increased the efficacy of influenza vaccination. Scutellaria baicalensis (huangqin) ameliorated irinotecan-induced gastrointestinal toxicity in cancer patients.Piper methysticum (kava) increased the 'off' periods in patients with parkinsonism taking levodopa and induced a semicomatose state when given concomitantly with alprazolam. Kava enhanced the hypnotic effect of alcohol in mice, but this was not observed in humans. Silybum marianum (milk thistle) decreased the trough concentrations of indinavir in humans. Piperine from black (Piper nigrum Linn) and long (P. longum Linn) peppers increased the AUC of phenytoin, propranolol and theophylline in healthy volunteers and plasma concentrations of rifamipicin (rifampin) in patients with pulmonary tuberculosis. Eleutheroccus senticosus (Siberian ginseng) increased the serum concentration of digoxin, but did not alter the pharmacokinetics of dextromethorphan and alprazolam in humans. Hypericum perforatum (hypericum; St John's wort) decreased the blood concentrations of ciclosporin (cyclosporin), midazolam, tacrolimus, amitriptyline, digoxin, indinavir, warfarin, phenprocoumon and theophylline, but did not alter the pharmacokinetics of carbamazepine, pravastatin, mycophenolate mofetil and dextromethorphan. Cases have been reported where decreased ciclosporin concentrations led to organ rejection. Hypericum also caused breakthrough bleeding and unplanned pregnancies when used concomitantly with oral contraceptives. It also caused serotonin syndrome when used in combination with selective serotonin reuptake inhibitors (e.g. sertraline and paroxetine). In conclusion, interactions between herbal medicines and prescribed drugs can occur and may lead to serious clinical consequences. There are other theoretical interactions indicated by preclinical data. Both pharmacokinetic and/or pharmacodynamic mechanis...

Pyruvate kinase (PYK) is an essential glycolytic enzyme that controls glycolytic flux and is critical for ATP production in all organisms, with tight regulation by multiple metabolites. Yet the allosteric mechanisms governing PYK activity in bacterial pathogens are poorly understood. Here we report biochemical, structural and metabolomic evidence that Mycobacterium tuberculosis (Mtb) PYK uses AMP and glucose-6-phosphate (G6P) as synergistic allosteric activators that function as a molecular “OR logic gate” to tightly regulate energy and glucose metabolism. G6P was found to bind to a previously unknown site adjacent to the canonical site for AMP. Kinetic data and structural network analysis further show that AMP and G6P work synergistically as allosteric activators. Importantly, metabolome profiling in the Mtb surrogate, Mycobacterium bovis BCG, reveals significant changes in AMP and G6P levels during nutrient deprivation, which provides insights into how a PYK OR gate would function during the stress of Mtb infection.

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The role of reactive oxygen species (ROS) in microbial metabolism and stress response has emerged as a major theme in microbiology and infectious disease. Reactive fluorescent dyes have the potential to advance the study of ROS in the complex intracellular environment, especially for high-content and high-throughput analyses. However, current dye-based approaches to measuring intracellular ROS have the potential for significant artifacts. Here, we describe a robust platform for flow cytometric quantification of ROS in bacteria using fluorescent dyes, with ROS measurements in 10s-of-1000s of individual cells under a variety of conditions. False positives and variability among sample types (e.g., bacterial species, stress conditions) are reduced with a flexible four-step gating scheme that accounts for side- and forward-scattered light (morphological changes), background fluorescence, DNA content, and dye uptake to identify cells producing ROS. Using CellROX Green dye with Escherichia coli, Mycobacterium smegmatis, and Mycobacterium bovis BCG as diverse model bacteria, we show that (1) the generation of a quantifiable CellROX Green signal for superoxide, but not hydrogen peroxide-induced hydroxyl radicals, validates this dye as a superoxide detector; (2) the level of dye-detectable superoxide does not correlate with cytotoxicity or antibiotic sensitivity; (3) the non-replicating, antibiotic tolerant state of nutrient-deprived mycobacteria is associated with high levels of superoxide; and (4) antibiotic-induced production of superoxide is idiosyncratic with regard to both the species and the physiological state of the bacteria. We also show that the gating method is applicable to other fluorescent indicator dyes, such as the 5-carboxyfluorescein diacetate acetoxymethyl ester and 5-cyano-2,3-ditolyl tetrazolium chloride for cellular esterase and reductive respiratory activities, respectively. These results demonstrate that properly controlled flow cytometry coupled with fluorescent probes provides precise and accurate quantitative analysis of ROS generation and metabolic changes in stressed bacteria.