Hydrogen sulfide acts as a mediator of inflammation in acute pancreatitis: in vitro studies using isolated mouse pancreatic acinar cells

Hydrogen sulphide (H(2)S) is synthesized from L-cysteine via the action of cystathionine-gamma-lyase (CSE) and cystathionine-beta-synthase (CBS). We have earlier shown that H(2)S acts as a mediator of inflammation. However the mechanism remains unclear. In this study, we investigated the presence of H(2)S and the expression of H(2)S synthesizing enzymes, CSE and CBS, in isolated mouse pancreatic acini. Pancreatic acinar cells from mice were incubated with or without caerulein (10(-7) M for 30 and 60 min). Caerulein increased the levels of H(2)S and CSE mRNA expression while CBS mRNA expression was decreased. In addition, cells pre-treated with DL-propargylglycine (PAG, 3 mM), a CSE inhibitor, reduced the formation of H(2)S in caerulein treated cells, suggesting that CSE may be the main enzyme involved in H(2)S formation in mouse acinar cells. Furthermore, substance P (SP) concentration in the acini and expression of SP gene (preprotachykinin-A, PPT-A) and neurokinin-1 receptor (NK-1R), the primary receptor for SP, are increased in secretagogue caerulein-treated acinar cells. Inhibition of endogenous production of H(2)S by PAG significantly suppressed SP concentration, PPT-A expression and NK1-R expression in the acini. To determine whether H(2)S itself provoked inflammation in acinar cells, the cells were treated with H(2)S donor drug, sodium hydrosulphide (NaHS), (10, 50 and 100 muM), that resulted in a significant increase in SP concentration and expression of PPT-A and NK1-R in acinar cells. These results suggest that the pro-inflammatory effect of H(2)S may be mediated by SP-NK-1R related pathway in mouse pancreatic acinar cells.     

Leptin secreted from testicular microenvironment modulates hedgehog signaling to augment the endogenous function of Leydig cells

Although testosterone deficiency (TD) may be present in one out of five men 40 years or older, the factors responsible for TD remain largely unknown. Leydig stem cells (LSCs) differentiate into adult Leydig cells (ALC) and produce testosterone in the testes under the pulsatile control of luteinizing hormone (LH) from the pituitary gland. However, recent studies have suggested that the testicular microenvironment (TME), which is comprised of Sertoli and peritubular myoid cells (PMC), plays an instrumental role in LSC differentiation and testosterone production under the regulation of the desert hedgehog signaling pathway (DHH). It was hypothesized that the TME releases paracrine factors to modulate LSC differentiation. For this purpose, cells (Sertoli, PMCs, LSCs, and ALCs) were extracted from men undergoing testis biopsies for sperm retrieval and were evaluated for the paracrine factors in the presence or absence of the TME (Sertoli and PMC). The results demonstrated that TME secretes leptin, which induces LSC differentiation and increases testosterone production. Leptin’s effects on LSC differentiation and testosterone production, however, are inversely concentration-dependent: positive at low doses and negative at higher doses. Mechanistically, leptin binds to the leptin receptor on LSCs and induces DHH signaling to modulate LSC differentiation. Leptin-DHH regulation functions unidirectionally insofar as DHH gain or loss of function has no effect on leptin levels. Taken together, these findings identify leptin as a key paracrine factor released by cells within the TME that modulates LSC differentiation and testosterone release from mature Leydig cells, a finding with important clinical implications for TD.Subject terms: Stem-cell differentiation, Translational research     

Antibacterial activity of silver nanoparticles (AgNps) synthesized by tea leaf extracts against pathogenic Vibrio harveyi and its protective efficacy on juvenile Feneropenaeus indicus

Aims: To determine the antibacterial potential of silver nanoparticles (AgNps) synthesized by tea leaf extract against Vibrio harveyi and its protective effect on juvenile Feneropenaeus indicus. Methods and Results: AgNps were synthesized by a simple procedure using tea leaf extract as the reducing agent. Bacteriological tests were performed in Luria–Bertani medium on solid agar plates and in liquid systems supplemented with V. harveyi against different concentrations of AgNps. AgNps synthesized in the present study were shown to be effective against V. harveyi isolated from F. indicus. The combined results of long‐ and short‐term treatment of AgNps synthesized by tea leaf extract showed a 71% reduction in accumulated mortality. Conclusions: The long‐term administration of AgNps synthesized by tea leaf extracts at the concentration of 10 μg significantly reduced the mortalities in F. indicus from V. harveyi infections. Significance and Impact of the Study: The AgNps synthesized by tea leaf extract may be an alternative to antibiotics in controlling V. harveyi infections.     

Improvement in bioreactor productivities using free radicals: HOCl-induced overproduction of xanthan gum from Xanthomonas campestris and its mechanism

Free-radical induction has been employed as a novel strategy to improve bioreactor productivity and, more specifically, the quality and productivity of xanthan gum from Xanthomonas campestris cultures. A 210% increase in xanthan yield and a 20% increase in viscosity (quality) resulted from HOCl (oxidant) treatment. The acetate mass fraction in xanthan gum decreased by 42% and its pyruvate mass fraction increased by 63% as a result of HOCl treatment. The growth rate was almost unaffected by HOCl treatment. A hypothesis to explain the mechanism of xanthan gum overproduction by free-radical induction has been formulated. The significant aspects of the hypothesis, such as SoxS protein binding to the promoter region of the gum gene and the consequent increase in mRNA concentrations, have been experimentally verified.     

Active nitric oxide produced in the red cell under hypoxic conditions by deoxyhemoglobin-mediated nitrite reduction

Recent studies have generated a great deal of interest in a possible role for red blood cells in the transport of nitric oxide (NO) to the microcirculation and the vascular effect of this nitric oxide in facilitating the flow of blood through the microcirculation. Many questions have, however, been raised regarding such a mechanism. We have instead identified a completely new mechanism to explain the role of red cells in the delivery of NO to the microcirculation. This new mechanism results in the production of NO in the microcirculation where it is needed. Nitrite produced when NO reacts with oxygen in arterial blood is reutilized in the arterioles when the partial pressure of oxygen decreases and the deoxygenated hemoglobin formed reduces the nitrite regenerating NO. Nitrite reduction by hemoglobin results in a major fraction of the NO generated retained in the intermediate state where NO is bound to Hb(III) and in equilibrium with the nitrosonium cation bound to Hb(II). This pool of NO, unlike Hb(II)NO, is weakly bound and can be released from the heme. The instability of Hb(III)NO in oxygen and its displacement when flushed with argon requires that reliable determinations of red blood cell NO must be performed on freshly lysed samples without permitting the sample to be oxygenated. In fresh blood samples Hb(III)NO accounts for 75% of the red cell NO with appreciably higher values in venous blood than arterial blood. These findings confirm that nitrite reduction at reduced oxygen pressures is a major source for red cell NO. The formation and potential release from the red cell of this NO could have a major impact in regulating the flow of blood through the microcirculation.     

Photodynamic effects of two hydroxyanthraquinones

The aim of this work was to investigate the photodynamic action of electron-rich anthraquinones, viz., cynodontin (CYN) and cynodontin-5,8-dimethylether (CYNM). Both optical and EPR methods are used to detect the generation of singlet oxygen. Based on RNO bleaching, relative to rose bengal (RB), singlet oxygen generating efficiencies of CYN and CYNM are derived to be 0.055 and 0.254, respectively. The formation of superoxide anion via electron transfer to O2 was monitored by optical spectroscopy, using SOD-inhibitable cytochrome c reduction assay. The production of O2-* is enhanced in the presence of electron donors such as EDTA and NADH. Photolysis of CYN and CYNM in DMSO, in the presence of 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), generates a multi-line EPR spectrum, characteristic of spin adduct mixture of O2-* and *OH. Both optical and ESR measurements indicate that O2-* (Type I) and 1O2 (Type II) paths are involved in CYN and CYNM photodynamic action.     

Sodium channel modulating activity in a delta-conotoxin from an Indian marine snail

A 26 residue peptide (Am 2766) with the sequence CKQAGESCDIFSQNCCVG-TCAFICIE-NH(2) has been isolated and purified from the venom of the molluscivorous snail, Conus amadis, collected off the southeastern coast of India. Chemical modification and mass spectrometric studies establish that Am 2766 has three disulfide bridges. C-terminal amidation has been demonstrated by mass measurements on the C-terminal fragments obtained by proteolysis. Sequence alignments establish that Am 2766 belongs to the delta-conotoxin family. Am 2766 inhibits the decay of the sodium current in brain rNav1.2a voltage-gated Na(+) channel, stably expressed in Chinese hamster ovary cells. Unlike delta-conotoxins have previously been isolated from molluscivorous snails, Am 2766 inhibits inactivation of mammalian sodium channels.     

Synthesis and biophysical studies of oligonucleotides containing hydroxamate linkages

Novel thymidine dimers containing hydroxamate linkages were synthesized, incorporated into oligonucleotide sequences and studied their hybridization properties against complementary DNA and RNA targets.     

Niacin protects the isolated heart from ischemia-reperfusion injury

Nicotinic acid (niacin) has been shown to decrease myocyte injury. Because interventions that lower the cytosolic NADH/NAD(+) ratio improve glycolysis and limit infarct size, we hypothesized that 1) niacin, as a precursor of NAD(+), would lower the NADH/NAD(+) ratio, increase glycolysis, and limit ischemic injury and 2) these cardioprotective benefits of niacin would be limited in conditions that block lactate removal. Isolated rat hearts were perfused without (Ctl) or with 1 microM niacin (Nia) and subjected to 30 min of low-flow ischemia (10% of baseline flow, LF) and reperfusion. To examine the effects of limiting lactate efflux, experiments were performed with 1) Ctl and Nia groups subjected to zero-flow ischemia and 2) the Nia group treated with the lactate-H(+) cotransport inhibitor alpha-cyano-4-hydroxycinnamate under LF conditions. Measured variables included ATP, pH, cardiac function, tissue lactate-to-pyruvate ratio (reflecting NADH/NAD(+)), lactate efflux rate, and creatine kinase release. The lactate-to-pyruvate ratio was reduced by more than twofold in Nia-LF hearts during baseline and ischemic conditions (P < 0.001 and P < 0.01, respectively), with concurrent lower creatine kinase release than Ctl hearts (P < 0.05). Nia-LF hearts had significantly greater lactate release during ischemia (P < 0.05 vs. Ctl hearts) as well as higher functional recovery and a relative preservation of high-energy phosphates. Inhibiting lactate efflux with alpha-cyano-4-hydroxycinnamate and blocking lactate washout with zero flow negated some of the beneficial effects of niacin. During LF, niacin lowered the cytosolic redox state and increased lactate efflux, consistent with redox regulation of glycolysis. Niacin significantly improved functional and metabolic parameters under these conditions, providing additional rationale for use of niacin as a therapeutic agent in patients with ischemic heart disease.     

Oxygen supply without gas-liquid film resistance to xanthomonas campestris cultivation

Alternative methods of oxygen supply are of crucial importance, especially in viscous fermentations and shear-sensitive fermentations. A method of oxygen supply that completely eliminates the gas-liquid transport resistance has been presented. The method involves a need-based liquid-phase decomposition of hydrogen peroxide to provide the necessary oxygen. When Xanthomonas campestris was cultivated (viscous cultivation) using this method of oxygen supply, dissolved oxygen (DO) levels were maintained above the setpoint of 50% throughout the cultivation, whereas the conventional cultivation was able to meet culture oxygen demand only for about 6 h in a 72-h fermentation. Furthermore, the maximum specific growth rate and xanthan yields in the novel cultivation were 89% and 169%, respectively, of those obtained in conventional cultivation. A mathematical model was also developed to simulate and predict results in fermentations employing the presented methodology. In addition, studies with HOCl pretreatments indicated that monofunctional catalase may be responsible for the decomposition of H2O2 supplied externally to cells; HOCl pretreatments also increased the tolerance of cells to H2O2. The decomposition kinetics of externally supplied H2O2 was Michaelis-Menten in nature with vmax = 1.196 x 10(-6) M s-1 and Km = 0.21 mM. The catalase concentration was estimated to be 3.4 x 10(-10) mol/g of cells. Copyright 1998 John Wiley & Sons, Inc.