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PubMed1976

[Interaction of complex esters of hydroxyethylsulfones with DNA in vitro].

The effect of a number of alkyl disulphones on the parameters of DNA melting following its treatment with the substances involved was studied under in vitro conditions: it was found that bis(acetyl oxyethylsulphonyl) methane and bis (formyl oxyethylsulphonyl) methane reduced the temperature of DNA melting. As a result of decomposition of oxyethylsulphone esters the corresponding vinylsulphones were formed. It is suggested that the parameters of DNA melting change under the influence of vinylsulphones being formed. There is some correlation between antitumor activity of alkyl disulphones and their capacity to interact with DNA. Inactive or insignificantly active substances would not influence the parameters of DNA melting, while the two substances under consideration possessed a high antitumor effect on ascites forms of animal tumors.

Alkanesulfonates↗
PubMed1985

An alkyl imidate labeling study of the organization of phospholipids and proteins in the lipid-containing bacteriophage PR4.

The structure of the lipid-containing bacteriophage PR4 was studied using two alkyl imidates, ethyl acetimidate (EAI), a reagent permeant to lipid bilayers and isethionyl acetimidate (IAI), which is impermeant to membranes. The virion is an icosahedral particle consisting of a protein coat surrounding a membrane of phospholipid and protein which in turn encloses the DNA genome. Upon exposure to the permeant reagent, EAI, 50% of the phosphatidylethanolamine (PE) molecules reacted rapidly (half-life less than 10 min). A similar fraction of the PE also reacted with IAI, the impermeant reagent. The remaining half of the PE molecules reacted slowly with EAI (half-life of 80 min) and failed to react with IAI. All of the phage proteins reacted with both EAI and IAI (except a DNA-associated protein which reacted only with EAI). These labeling results indicate that the phage membrane consists of a lipid bilayer and that at least a portion of each phage protein (except the DNA-associated protein) is exposed on the external face of the lipid bilayer. Several of the membrane proteins could be cross-linked either to the phage membrane PE after EAI treatment or to phage phosphatidylglycerol after periodate treatment. The major structural protein of the phage was readily cross-linked to PG but failed to cross-link to PE suggesting that the protein specifically interacts with PG.

Cross-Linking Reagents↗
PubMed1982

Granule fusion and fission (discharge) are biochemically dissociable events of exocytotic hormone release.

Granule fusion and the subsequent fission leading to hormone discharge are distinct and separable events in exocytosis. As an index of fusion, we followed the recruitment of granule-bound somatostatin receptors to the islet surface, an event which accompanies secretion vesicle migration and insulin secretion. Granule fission was monitored by measuring insulin release. Substitution of the impermeant salt sodium isethionate for NaCl led to a 90% decrease in glucose-stimulated insulin release with no inhibition of somatostatin receptor recruitment. The phenothiazine drugs, trifluoperazine and promethazine, believed to inhibit calcium-sensitive proteins involved with stimulus-secretion coupling blocked insulin release and somatostatin receptor recruitment in parallel. This suggests that these agents suppress intracellular events promoting fusion of the secretion granule with the plasma membrane. IBMX appears to stimulate specifically granule fission since IBMX-induced insulin release occurs acutely without an increase in somatostatin receptor recruitment. Sodium isethionate, which inhibits granule lysis, blocked IBMX-stimulated insulin release.

1-Methyl-3-isobutylxanthine↗
PubMed1981

[Tonic mechanisms of efferent inhibition in the frog labyrinth].

Activation of the efferent system of the isolated group labyrinth inhibits the afferent EPSP and spike discharge by releasing ACh, which opens the Cl- channel of the hair cells membrane. Experiments in which increasing amounts of Cl- in the bath are replaced by equivalent amounts of Br-, NO2-, NO3-, CH3 CO2-, SO4(2-), CH3CH2CO2-, CH3(CH2)2CO2-, CH3(CH2)3CO2- benzoate, indicate that all these anions are able to penetrate the postsynaptic membrane, since full inhibition was invariably elicited. On the other hand, when citrate or isethionate are substituted for Cl- inhibition disappeared. In the presence of anions which are known to chelate calcium, its bath concentration was adequately increased. The presence of inhibition of Ringer-benzoate (benzoate ion size 6.5 A) and its disappearance in Ringer-citrate (8 A) or in Ringer-isethionate (greater than 10 A), suggests that the Cl- channel is at least 7 A in diameter, a size significantly larger than at other inhibitory synapses. Since metabolic inhibitors (DNP 0.1 mM and NaN3 1 mM) or acetazolamide (5 mM) and ammonium acetate (10 mM), which are known to block active Cl- pumping in other systems, do not affect the efferent synapse it appears difficult to interfere with the mechanisms which maintain the Cl- concentration gradient across the hair cell membrane.

Animals↗
PubMed1993

Sulfonate-sulfur assimilation by yeasts resembles that of bacteria.

Three sulfonates were tested for their ability to serve as nutrients for Hansenula wingei, Rhodotorula glutinis, Trigonopsis variabilis and Saccharomyces cerevisiae. Cysteate, taurine and isethionate, under aerobic conditions, could be utilized as sources of sulfur, although in some instances final cell yields were less than those obtained with an equimolar amount of sulfate-sulfur. Sulfonate assimilation by S. cerevisiae resembled that of bacteria (reported earlier by us) in several aspects: first, sulfate-S was used in preference to that of sulfonate, when both were present; second, mutants unable to use sulfate as a source of sulfur because of deficiencies in ATP sulfurylase, adenylylsulfate kinase (APS kinase) or PAPS reductase were able to utilize sulfonates; and third, mutants deficient in sulfite reductase were unable to utilize sulfonates.

Aerobiosis↗
PubMed1976

Action of amino acids and convulsants on cerebellar spontaneous action potentials in vitro: effects of deprivation of C1-, K+ of Na+.

(1) The inhibition of spontaneous action potentials in guinea pig cerebellar cortex slices by GABA, glycine, taurine and beta-alanine is maintained when C1- in the superfusion medium is almost completely replaced by NO3- or I-('permeant' anion), but the inhibition decreases in magnitude with repeated application of the amino acid. Replacement of C1- by sulfate or isethionate ('impermeant' anion) causes a conversion of inhibition by these amino acids to excitation. The initial excitation which is sometimes seen with these inhibitory amino acids in high C1- media is abolished when C1- is replaced by either permeant or impermeant anions. (2) Reduction of K+ in the medium causes an increase of inhibition by the inhibitory amino acids in the presence of high C1- and reduction of excitation when C1- is replaced by impermeant anion. (3) Excitation by GABA in impermeant anion (low C1-) media is unaffected by reduction of Na+ in the media by 50% but excitations by glycine, taurine, beta-alanine and L-glutamate are greatly reduced. (4). Excitation by GABA in impermeant anion (low C1-) media is abolished by picrotoxin and bicuculline which both suppress inhibition by GABA in a high C1- medium. Strychnine suppresses the effects of glycine, taurine and beta-alanine in either a low or high C1- medium. Bicuculline blocks the inhibitory effect of these three amino acids in a high C1- medium but does not affect their excitatory effects in a low C1- medium. (5) These results are consistent with the hypothesis that the inhibitory amino acids, GABA, glycine, taurine and beta-alanine, cause inhibition via increase of C1- (and perhaps K+) permeability and that glycine, taurine and beta-alanine also interact with strychnine-sensitive receptors mediating (perhaps indirectly) increased permeability to Na+ and, therefore, excitation in low C1- media.

Action Potentials↗
PubMed1993

Cl- replacement alters the ventilatory response to central chemoreceptor stimulation.

To determine whether cerebrospinal fluid (CSF) Cl- has a role in determining the stimulus to the central respiratory chemoreceptors under conditions of constant CSF pH, CO2, and HCO3- concentrations, the ventral medullary surface of the anesthetized rat was perfused with mock CSF of various ion composition and pH. Four mock CSF perfusates were used: two normal pH control perfusions and two acidic solutions. One acidic perfusate was formulated in the traditional manner by substituting Cl- for HCO3-. The second acidic perfusate, and one of the normal pH control perfusates, had approximately 15% of the Cl- replaced with isethionate, an impermeant strong anion. When the two acidic solutions were perfused over the ventral medulla, consistently larger increases in both tidal volume and minute ventilation were observed with the isethionate-containing acidic solution, despite conditions of identical pH and PCO2. The unequal ventilatory effects of the two acidic perfusions suggest that Cl- transport may be a factor determining the stimulus to the central respiratory chemoreceptors.

Animals↗
PubMed1994

Anti-tumor necrosis factor properties of non-peptide drugs in acute-phase responses.

Dexamethasone (sodium phosphate), pentoxifylline, fusidic acid (sodium salt), pentamidine (isethionate) and R-phenylisopropyladenosine (R-PIA) were tested for their anti-tumor necrosis factor (TNF) activities in an endotoxin-induced shock rat model. All the drugs reduced serum TNF concentrations in a dose-dependent manner, whereas their effects on serum interleukin-6 levels differed. Doses that reduced TNF levels by 50% were 0.012 mg/kg for dexamethasone, 0.06 mg/kg for R-PIA, 0.24 mg/kg for pentamidine, 6.5 mg/kg for fusidic acid and 15 mg/kg for pentoxifylline. Administration of the drugs to rats before intraplantar injection of carrageenan reduced paw edema by 50-70%. Injection of a monoclonal anti-TNF antibody reproduced the inhibitory effect. Moreover, the time course of tissue-associated TNF following carrageenan injection was compatible with mediation of edema by TNF. Results obtained for this acute, non-immunological inflammatory reaction strongly suggest that the model is TNF-dependent. Our results reinforce the idea that TNF is a crucial target in the therapeutics of inflammatory reactions. These drugs, which are able to cross cell barriers, might have clinical applications in localized and/or chronic diseases in which TNF is involved.

Acute-Phase Reaction↗
PubMed1985

Influence of phosphate, sulfonic, and sulfamic acids on sulfoconjugate release in the vascularly perfused mouse small intestine.

An in vitro vascularly and luminally perfused preparation of the murine small intestine was used to investigate the interference of isethionate, cyclamate and HEPES (N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid) with the luminal transport of the isoprenaline-sulfoconjugate as well as with the basolateral transport of naphthol-sulfoconjugate. The sulfonates and sulfamates when administered from the luminal as well as from the contraluminal side of the epithelium inhibited the transport of isoprenaline-sulfoconjugate. Inhibition of the naphthol-sulfoconjugate transport across the contraluminal epithelial membrane was less pronounced, but a countertransport phenomenon could be induced with cyclamate in the vascular medium. The presence of phosphate at the luminal side is essential for the transport of the isoprenaline-sulfoconjugate across the luminal membrane. This is not the case for bicarbonate. The conclusion is drawn that different transport systems for sulfoconjugates exist in the luminal and in the contraluminal membranes of the intestinal mucosa, which can be inhibited by structurally related compounds. The luminal transport system can be activated from the luminal side by phosphate.

Animals↗
PubMed1991

Genetic characterisation of resistance to metal ions in methicillin-resistant Staphylococcus aureus: elimination of resistance to cadmium, mercury and tetracycline with loss of methicillin resistance.

Susceptibility to six metal ions--cadmium (Cd), mercury (Hg), arsenate (Asa), arsenite (Asi), antimony (Sb) and zinc (Zn)--was tested in 23 independent isolates of methicillin-resistant Staphylococcus aureus (MRSA) obtained from Guy's Hospital (GH) during 1984-1986, which included 10 isolates of the UK epidemic EMRSA-1 strain. Strains were also tested for resistance to antibiotics and the nucleic-acid-binding compounds propamidine isethionate and ethidium bromide. A further 19 methicillin-resistant isolates, including 10 EMRSA-1 were obtained from other sources. Ten methicillin-sensitive, antibiotic sensitive isolates were from Guy's Hospital. Resistance to Hg was associated with methicillin resistance in 19 of the 20 EMRSA-1 isolates, all of which were resistant to Cd. Resistance to Cd and Hg was found in 13 out of 22 other MRSA isolates. Hg resistance was not present in the methicillin-sensitive isolates which were often (13 out of 19) moderately resistant to Cd. Multiple resistance to metal ions, including resistance to Hg, Asa, Asi and Sb, was uncommon. Resistance to Cd (MIC greater than 32 mg/L or 8-16 mg/L) was associated with increased resistance to Zn. In 11 of the consecutive MRSA isolates from Guy's Hospital seven distinct strains were recognised by phage type. Methicillin resistance in these strains varied from 16 to 1024 mg/L at 30 degrees C with a 2-8-fold lower minimum inhibitory concentration at 37 degrees C indicating some degree of heterogeneity. Representatives of the EMRSA-1 strain had the higher levels of resistance. Loss of methicillin resistance occurred in 0.2-5.0% of colonies tested after storage at room temperature in 10 of these isolates.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacteriophages↗
PubMed1997

Role of anions in the regulation of cell volume and intracellular pH in perfused rat mandibular salivary gland.

To investigate the role of Cl- in the regulation of the basolateral transporters of salivary acinar cells, we have measured cell volume and intracellular pH (pHi) in perfused rat mandibular glands using proton NMR spectroscopy and BCECF fluorometry respectively. When perfusate Cl- was replaced by glucuronate, isethionate, methylsulphate, nitrate or thiocyanate, cell volume decreased slowly by about 15% over a 10-min period. Replacement with bromide, which substitutes for Cl- on the Na+-K+-2Cl- cotransporter, caused only a small (4%) reduction in cell volume. Replacement of Cl- by glucuronate, isethionate or methylsulphate evoked a biphasic increase in pHi consisting of a rapid initial increase followed by a slower secondary rise whose time course was similar to that of cell shrinkage. As judged by the effects of HCO3- omission, 100 microM 4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid (DIDS) and 1 mM amiloride, the initial rise in pHi was due to Cl-/HCO3- exchange while the secondary rise resulted from activation of Na+/H+ exchange. Although replacement of Cl- by nitrate or thiocyanate also caused cell shrinkage, these substituting anions were less effective in activating the exchanger. Therefore, while the upregulation of the exchanger following Cl- replacement may be due in part to cell shrinkage, there is also evidence for the involvement of an anion-sensitive regulatory mechanism. This would be consistent with the hypothesis that both changes in cell volume and in intracellular Cl- concentration contribute to the up-regulation of the exchanger following muscarinic stimulation.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1999

Chloride channel blockers attenuate the inhibition of renin secretion by angiotensin II.

The aim of this study was to assess the relevance of chloride channels to the inhibitory effect of angiotensin II (ANGII) on renin secretion. We thus examined the effects of the chloride channels blockers IAA-94 and niflumic acid, the Na-K-Cl cotransport blocker bumetanide and substitution of isethionate for extracellular chloride on the action of ANGII on renin secretion from isolated perfused rat kidneys. Renin secretion prestimulated by isoproterenol (10 nmol/l) was almost completely blocked by ANGII with a concentration yielding a half-maximal response (EC50) of around 150 nmol/l. In the presence of IAA-94 and niflumic acid the EC50 for ANGII was shifted to about 400 nmol/l. In the presence of bumetanide and isethionate renin secretion responded more sensitively to ANGII and the EC50 for ANGII was below 100 nmol/l. On the assumption that the chloride equilibrium potential in renin-secreting cells is more positive than the membrane potential, our findings would suggest that the inhibitory effect of ANGII is enhanced when chloride entry is blocked and attenuated when chloride efflux is impaired. Activation of chloride channels therefore probably contributes to the inhibitory action of ANGII on renin secretion.

Angiotensin II↗
PubMed1993

Sulphonate utilization by enteric bacteria.

A variety of sulphonates were tested for their ability to serve as nutrients for Escherichia coli, Enterobacter aerogenes and Serratia marcescens. Cysteate, taurine and isethionate could not serve as sole sources of carbon and energy but, under aerobic conditions, could be utilized as sources of sulphur. Both sulphate and sulphonate supported equivalent cell yields, but the generation times varied with the sulphonate being metabolized. The sulphonate-S of HEPES buffer, dodecane sulphonate and methane sulphonate was also utilized by some strains, whereas the sulphonate-S of taurocholate was not. None of the sulphonates tested served as a sulphur source for growth under anaerobic conditions. Sulphonate utilization appears to be a constitutive trait; surprisingly, however, cells of E. coli and Ent. aerogenes utilized sulphate-S in preference to that of sulphonate, when both were present. E. coli mutants unable to use sulphate as a source of sulphur because of deficiencies in sulphate permease, ATP sulphurylase, adenylylsulphate kinase (APS kinase) or glutaredoxin and thioredoxin were able to utilize sulphonates; hence sulphate is not an obligatory intermediate in sulphonate utilization. However, mutants deficient in sulphite reductase were unable to utilize sulphonates; therefore, this enzyme must be involved in sulphonate utilization, though it is not yet known whether it acts upon the sulphonates themselves or upon the inorganic sulphite derived from them.

Anaerobiosis↗
PubMed1981

Effects of chloride substitutes on PAH transport by isolated perfused renal tubules.

Effects of substituting isethionate, methyl sulfate, or thiocyanate for chloride on p-aminohippurate (PAH) transport by isolated perfused snake (Thamnophis spp.) distal-proximal renal tubules were studied. In the perfusate, isethionate or methyl sulfate substitution irreversibly depressed net PAH secretion and the apparent PAH permeability of the luminal membrane by about 60-80%, whereas thiocyanate substitution had no effect. In the bathing medium, isethionate substitution reversibly stimulated net PAH secretion by about 35% without changing the apparent permeability of the peritubular membrane to PAH (Pp); thiocyanate substitution reversibly inhibited net PAH secretion by about 45% without affecting Pp; and methyl sulfate substitution had no effect. With simultaneous substitutions in perfusate and bath, isethionate depressed net PAH secretion irreversibly, whereas thiocyanate had no effect. Effects on PAH transport were not simply the result of changes in transepithelial potential or of the changes in net transepithelial fluid movement. These data strengthen the concept that net PAH secretion involves different mediated steps at the peritubular and luminal membranes. Since these tubules are highly permeable to thiocyanate and poorly permeable to isethionate and methyl sulfate, the data suggest that the mediated step from cells to lumen does not require chloride in the lumen but does require a highly permeant anion.

Aminohippuric Acids↗
PubMed1997

Taurine reduction in anaerobic respiration of Bilophila wadsworthia RZATAU.

Organosulfonates are important natural and man-made compounds, but until recently (T. J. Lie, T. Pitta, E. R. Leadbetter, W. Godchaux III, and J. R. Leadbetter. Arch. Microbiol. 166:204-210, 1996), they were not believed to be dissimilated under anoxic conditions. We also chose to test whether alkane- and arenesulfonates could serve as electron sinks in respiratory metabolism. We generated 60 anoxic enrichment cultures in mineral salts medium which included several potential electron donors and a single organic sulfonate as an electron sink, and we used material from anaerobic digestors in communal sewage works as inocula. None of the four aromatic sulfonates, the three unsubstituted alkanesulfonates, or the N-sulfonate tested gave positive enrichment cultures requiring both the electron donor and electron sink for growth. Nine cultures utilizing the natural products taurine, cysteate, or isethionate were considered positive for growth, and all formed sulfide. Two clearly different pure cultures were examined. Putative Desulfovibrio sp. strain RZACYSA, with lactate as the electron donor, utilized sulfate, aminomethanesulfonate, taurine, isethionate, and cysteate, converting the latter to ammonia, acetate, and sulfide. Strain RZATAU was identified by 16S rDNA analysis as Bilophila wadsworthia. In the presence of, e.g., formate as the electron donor, it utilized, e.g., cysteate and isethionate and converted taurine quantitatively to cell material and products identified as ammonia, acetate, and sulfide. Sulfite and thiosulfate, but not sulfate, were utilized as electron sinks, as was nitrate, when lactate was provided as the electron donor and carbon source. A growth requirement for 1,4-naphthoquinone indicates a menaquinone electron carrier, and the presence of cytochrome c supports the presence of an electron transport chain. Pyruvate-dependent disappearance of taurine from cell extracts, as well as formation of alanine and release of ammonia and acetate, was detected. We suspected that sulfite is an intermediate, and we detected desulfoviridin (sulfite reductase). We thus believe that sulfonate reduction is one aspect of a respiratory system transferring electrons from, e.g., formate to sulfite reductase via an electron transport system which presumably generates a proton gradient across the cell membrane.

Acetates↗