Effect of calcium channel blocker diltiazem on cytoprotection and prostaglandin and sulfhydryl production by rat gastric epithelial cells.

The calcium channel blockers verapamil and diltiazem protect gastric mucosa against exogenous injury in vivo. Whether this protection is mediated by systemic factors, such as blood flow, is due to inhibition of gastric acid secretion, or is associated with stimulation of endogenous protective agents such as prostaglandins or sulfhydryls, is unknown. We have evaluated whether diltiazem protects rat gastric epithelial cells in tissue culture (a model which excludes the influence of systemic factors) against damage induced by sodium taurocholate, indomethacin, or ethanol. Further we have assessed the effect of diltiazem on prostaglandin and sulfhydryl production. 51Chromium release assay and phase contrast microscopy have been used to assess cell damage. Sodium taurocholate, indomethacin, and ethanol-damaged cultured cells in a dose-dependent manner. Pretreatment with diltiazem did not prevent the drug-induced damage. Diltiazem did not increase PGE2 and 6-keto PGF1a production by cultured cells nor did it affect the cellular level of endogenous sulfhydryls. In conclusion, the calcium channel blocker diltiazem is not directly protective to rat gastric mucosal cells in vitro. Diltiazem does not stimulate prostaglandin production by gastric cells nor does it increase the cellular level of protective sulfhydryls.

Desulfuration of cysteine and methionine by Fusobacterium nucleatum.

Fusobacterium nucleatum is a Gram-negative anaerobic rod-shaped bacterium frequently isolated from human dental plaque. It is capable of the desulfuration of cysteine and methionine, resulting in the formation of sulfide and thiol volatiles, respectively. Intact cells, as well as cell-free extracts produced by French pressure cell lysis of F. nucleatum, hydrolyzed radiolabeled cysteine to produce sulfide, pyruvic acid, and ammonia. The hydrolysis products of radiolabeled methionine were a volatile thiol, ketobutyrate, and ammonia. Both activities were associated with the cytoplasmic component, not the membrane. The desulfuration mechanisms are heat-labile, inhibited by the presence of excess substrate, and rates are dependent upon substrate concentration. These dissimilar pathways by F. nucleatum can account in part for the presence of sulfur-containing volatile products that occur in the mouth.

Depletion and resynthesis of tissue thiols by helenalin and tenulin.

The depletion of tissue thiols by two anti-leukemic agents helenalin and tenulin was studied in mice. Helenalin (100 mg/kg) and tenulin (213 mg/kg) in dimethyl sulfoxide (DMSO) were administered orally, and the acid-soluble total thiol concentrations in the liver, kidney, stomach and small intestine were determined at 0.5, 1.0, 3.0, 6.0, 12.0 and 24.0 hr post-treatment. The lowest tissue thiol levels (42-84% of pretrial values) were observed within 0.5 - 1.0 hr following helenalin treatment. The tenulin treated mice exhibited the lowest values (46-80% of pretrial control values) at 3.0 hr post-treatment in all tissues except in the stomach, which reached its lowest value at 1.0 hr. The most dramatic effects were found in the stomach and small intestine where the mean thiol concentrations varied from 43% to 141% (at 1.0 and 24.0 hr) and from 76% to 169% (at 0.5 and 24.0 hr) of pretrial values, respectively, among helenalin treated mice. The tissue thiol levels in DMSO- and physiological saline (PSS)-treated mice fluctuated probably due to fasting and/or diurnal changes.

Inhibition of Candida albicans by methanethiol produced by Brevibacterium linens.

Brevibacterium linens was screened for antifungal activity against Candida albicans using several antibiotic assay methods. The growth of C. albicans was inhibited only when the dual culture assay method was employed and using methionine-supplemented media. Results suggest that methanethiol which is produced by B. linens' utilization of methionine is the agent inhibitory to C. albicans' growth.

Production of methanethiol from methionine by Brevibacterium linens CNRZ 918.

The conditions under which Brevibacterium linens CNRZ 918, a strain isolated from the surface smear flora of Gruyère de Comté cheese, produced methanethiol from methionine were studied. Demethiolation was estimated from the methanethiol production capacity of resting cells. Methionine was demethiolated mainly during the exponential growth phase of the organism during which time the cells were rod-shaped and had a generation time of 5 h, and the medium became alkaline. At the end of growth (pH 9) the cells were coccoid, and produced only very little methanethiol. The production of methanethiol required the presence of methionine in the culture medium, this reflecting the probable induction of the enzyme systems involved. Glucose favoured growth and inhibited production of methanethiol. Lactate favoured both growth and methanethiol production. Resting rod cells also produced methanethiol from structural analogues of methionine and from methionine-containing peptides. The apparent kinetic constants of the production of methanethiol for rod and coccoid cells were respectively Km = 14 mM and 46 mM, Vmax = 208 nkat g-1 and 25 nkat g-1. The optimum temperature and pH for production were 30 degrees C and pH 8. Azide or malonate favoured the production of methanethiol by resting cells, whereas chloramphenicol had no effect.

Identification of Brevibacterium from clinical sources.

Coryneform bacteria of the genus Brevibacterium occur on the normal skin surface, but reports of human infection with this genus are lacking. A number of cultures of coryneform bacteria sent to the National Collection of Type Cultures for identification have been identified as Brevibacterium spp on the basis of their cell wall composition and ability to produce methane-thiol from L-methionine. We describe a rapid method for the detection of methane-thiol and confirmatory tests which differentiate Brevibacterium from morphologically similar genera.

[Effect of thiol compounds on experimental liver damage (IV). Detoxicating effect of tiopronin, glutathione and cysteine on ethionine induced lived damage (author's transl)].

S-GPT elevated due to ethionine (Eth) administration was suppressed by thiol compounds such as tiopronin (2-mercaptopropionylglycine), glutathione, cysteine, in which tiopronin proved to be more effective than glutathione or cysteine. In thin-layer chromatography of urinary metabolites, Eth and ethionine sulfoxide were detected with administration of Eth, and S-ethyltiopronin plus Eth and ethionine sulfoxide by the administrations of Eth and tiopronin. These S-ethyl derivatives were not detected in the urine with administration of Eth and glutathione or cysteine. In the analysis of Eth and its metabolites by gas chromatography, cumulative urinary excretion of Eth within 72 hr after Eth administration was 40.7% in the Eth administered group, 23.6% in the Eth-tiopronin administered group and 38.2% in the Eth-glutathione administered group, respectively. In the urine of the Eth-tiopronin administered group, S-ethyltiopronin was excreted by 13.6%. Detoxicating effect of tiopronin on Eth induced liver damage was considered to involve the following mechanism. Tiopronin is considered to excrete part of Eth as S-ethyltiopronin by being an acceptor of transfer reaction of the ethyl group of Eth. Neither glutathione nor cysteine was an acceptor of the ethyl group and a detoxicating effect on Eth was not observed.

Formation of sulfhydryl groups in the walls of Eimeria stiedai and E. tenella oocysts subjected to in vitro excystation.

Eimeria stiedai or Eimeria tenella oocysts were incubated in aqueous cysteine hydrochloride (cysHCl) under carbon dioxide (CO2), aqueous cysHCl under air, water under CO2 or water under air, and analyzed for sulfhydryl (-SH) groups. The cysHCl-CO2 treatment produced more -SH groups than the other treatments and was effective in allowing activation of intact and sodium hypochlorite (NaOCl)-treated E. stiedai oocysts as well as NaOCl-treated E. tenella oocysts. The CO2-cysHCl complex may act directly on the oocyst wall, especially in the micropylar region, to unmask lipid-shielded disulfide bridges, which are reduced to -SH groups. The reduction apparently disturbs the protein superstructure of the oocyst wall, promotes opening of the micropyle, and changes the impermeable state of the sporulated oocyst.

Volatile compounds produced in sterile fish muscle (Sebastes melanops) by Pseudomonas putrefaciens, Pseudomonas fluorescens, and an Achromobacter species.

Volatile compounds produced by Pseudomonas putrefaciens, P. fluorescens, and an Achromobacter species in sterile fish muscle (Sebastes melanops) were identified by combined gas-liquid chromatography and mass spectrometry. Compounds produced by P. putrefaciens included methyl mercaptan, dimethyl disulfide, dimethyl trisulfide, 3-methyl-1-butanol, and trimethylamine. With the exception of dimethyl trisulfide, the same compounds were produced by an Achromobacter species. Methyl mercaptan and dimethyl disulfide were the major sulfur-containing compounds produced by P. fluorescens.

Identification of the volatile compounds produced in sterile fish muscle (Sebastes melanops) by Pseudomonas fragi.

Volatile compounds produced by Pseudomonas fragi strain 18 in sterile fish muscle (Sebastes melanops) were identified by combined gas-liquid chromatography and mass spectrometry. Compounds positively identified included dimethyl sulfide, acetaldehyde, ethyl acetate, ethyl alcohol, and dimethyl disulfide. Methyl mercaptan, ethyl butyrate, ethyl hexanoate, and butanone were tentatively identified by relative retention times of the authentic compounds. The fruity odor that developed in fish muscle during incipient spoilage was attributed to a synergistic flavor interaction involving the ethyl esters of acetate, butyrate, and hexanoate.

Volatile compounds produced in sterile fish muscle (Sebastes melanops) by Pseudomonas perolens.

Volatile compounds produced by Pseudomonas perolens ATCC 10757 in sterile fish muscle (Sebastes melanops) were identified by combined gas-liquid chromatography and mass spectrometry. Compounds positively identified included methyl mercaptan, dimethyl disulfide, dimethyl trisulfide, 3-methyl-1-butanol, butanone, and 2-methoxy-3-isopropylpyrazine. Compounds tentatively identified included 1-penten-3-ol and 2-methoxy-3-sec-butylpyrazine. The substituted pyrazine derivative 2-methoxy-3-isopropylpyrazine was primarily responsible for the musty, potato-like odor produced by P. perolens.