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PubMed1989

Some properties of Streptococcus faecalis subsp. liquefaciens isolated from cheese with special reference to production of bitterness.

Streptococcus faecalis subsp. liquefaciens was examined for proteolysis and development of bitterness in sterile buffaloes' skim milk with and without some additives. Cell population and the pH of milk were the most important factors in the breakdown of casein and development of bitterness. Sodium chloride level, altering the final concentration of bacteria in milk, had a direct role in the production of bitter peptides. Calcium ions up to 5 mM did not affect proteolysis whereas higher concentrations were inhibitory. Electrophoretic analysis of proteose-peptone formed in sterile skim milk with and without NaCl revealed the presence of 3 peptides, 2 of which were probably associated with bitterness. S. faecalis subsp. liquefaciens produced acidity slowly, but was the most acid producer (1.25% after 72 h) of the streptococci. However, milk coagulated enzymatically and the curd shrinkage was related to salt-dependent acidity. Strains of the organism coagulated fresh citrated human plasma within 21 h at 30 degrees C, but without any visible fibrinolysis. The strains also were all alpha-haemolytic with occasionally a very few beta-haemolytic variants on sheep blood agar. On human blood agar, a weak alpha-reaction was given.

Animals↗
PubMed1988

Mitochondria-rich cells and carbonic anhydrase content of toad skin epithelium.

The density and carbonic anhydrase (CA) content of the mitochondria-rich cells (MRCs) in the skin epithelium of the toad, Bufo viridis, were studied under conditions of acclimation to various chlorinities. Long-term (days to weeks) acclimation to chloride-free solutions induced a great increase in the MRC density and the area occupied by the apical portion of these cells on the surface of the epithelium. The CA content of the epithelium, and individual MR cells, showed a 5- to 10-fold reduction after acclimation to solutions containing high chloride levels. The MRC density and their relative apical surface area correlated with the chloride permeability of the skin in acclimated (long-term) toads. It is concluded that the MRCs are the principal site of chloride permeability across the amphibian skin, and they respond in an adaptive manner to long-term changes in environmental chloride levels.

Animals↗
PubMed2005

Detection of chlorinated DNA and RNA nucleosides by HPLC coupled to tandem mass spectrometry as potential biomarkers of inflammation.

Upon inflammation, activated neutrophils secrete myeloperoxidase, an enzyme able to generate hypochlorous acid (HOCl) from hydrogen peroxide and chloride ions. An analytical method, involving HPLC coupled to electrospray tandem mass spectrometry, has been set-up to detect low levels of HOCl-induced nucleic acids lesions, including both ribo and 2'-deoxyribonucleoside derivatives of 8-chloroguanine, 8-chloroadenine and 5-chlorocytosine. Validation of the developed method was achieved using isolated cells treated with HOCl. The method was found to be sensitive enough to allow the measurement of background levels of 5-chloro-2'-deoxycytidine in the DNA of human white blood cells isolated from 7 mL of blood.

Adenine↗
PubMed1990

Electrical analysis of fresh, excised human skin: a comparison with frozen skin.

Samples of human allograft skin prepared without freezing ("fresh skin") were found to have electrical and sodium ion transport properties which differed only slightly from those of skin which had been similarly treated but stored frozen ("frozen skin"). The fresh skin samples were less permeable to sodium ions during passive diffusion and less conductive than frozen skin at low current levels. They were more permselective for sodium versus chloride during constant-current iontophoresis and showed slightly more asymmetry in their current-voltage properties. Overall, the electrical behavior of the two tissues was similar enough to support the use of frozen tissue in iontophoresis studies. However, caution should be exercised when considering the use of frozen skin for applications, such as those based on electroosmosis, where the observed differences could have a major impact on the results.

Diffusion↗
PubMed1989

The molecular basis of chloride channel dysregulation in cystic fibrosis.

The opening and closing of chloride (Cl-) channels in the apical membrane of epithelial cells is regulated by hormones, neurotransmitters and enterotoxins (intestine) acting through a variety of intracellular messengers, including cyclic nucleotides (cAMP, cGMP), calcium (Ca) and diacylglycerol (DAG). The chloride impermeability of epithelial membranes observed in cystic fibrosis (CF) patients does not result from a defect in the Cl- conducting properties of the channel or in channel recruitment but stems either from a defect in a key regulator of the channel, presumably a phosphoprotein, or from the hyperactivation of a channel closing mechanism, presumably a protein phosphatase or a down-regulating protein kinase (i.e. protein kinase C). In vitro phosphorylation of isolated intestinal brush border membranes has revealed the existence of a 25,000 molecular weight proteolipid (p25) acting as cosubstrate for both cGMP- and cAMP-dependent protein kinases and cross-reacting with antibodies directed against the cytoplasmic tail of the band 3 anion exchanger from erythrocytes. The putative role of p25 in Cl- channel regulation and its relationship to an unidentified GTP-binding protein recently implicated in Cl- channel activation is discussed on the basis of a regulatory model indicating potential sites of the CF defect at a molecular level.

Cell Membrane Permeability↗
PubMed1983

Sodium induces oxytocin release from superfused rat pituitary.

The effects of various osmotic agents on the release of oxytocin were examined in a superfusion system. Oxytocin was released significantly from the rat pituitary by superfusion with medium of an osmolality of 350 mOsm/kg H2O adjusted with NaCl, regardless of the presence of the rat hypothalamus. Media adjusted to an osmolality of 350 mOsm/kg H2O with sucrose, glucose, urea or mannitol had no effect on oxytocin release from the hypothalamo-pituitary complex. Medium containing excess Na2SO4 induced significant release of oxytocin from the pituitary without the hypothalamus. The administration of tetraethylammonium chloride had no oxytocin secretion. These data suggest that oxytocin release from the pituitary is influenced by the level of sodium ion rather than the osmotic pressure.

Animals↗
PubMed1977

[Strict additivity of the antispasmodic effects of papaverine and tiemonium: an example of sequential blockage].

The interaction of papaverine and tiemonium alone or combined, with BaCL2 and histamine on guinea pig ileum and with acetylcholine on rat jejunum have been studied with the help of molecular pharmacology techniques. The competitive antagonist effects of tiemonium and the non competitive antagonist effects of papaverine are evidenced and shown to be strictly additive when the two drugs are combined. This reflects a sequential blockage of the effects of acetylcholine, histamine and barium ions at the smooth muscle level. No such antagonism has been previously described in the case of the interaction with barium chloride with any other combination of two spasmolytic drugs.

Acetylcholine↗
PubMed1991

Computer-simulated evaluation of possible mechanisms for quenching heavy metal ion activity in plant vacuoles: I. Cadmium.

Various mechanisms have been suggested for the quenching of Cd ion activity in plant vacuoles. These include solution complexation with organic acids and sulfhydryl-containing peptides and precipitation as sulfides. Because direct experimental support for these mechanisms is lacking and difficult to obtain, we have used a computer model to evaluate the quenching role of possible organic and inorganic ligands of tobacco cultured cells exposed to Cd. Results of this thermodynamic evaluation, which assumes that a chemical equilibrium state is met in the vacuole, support the conclusion that sulfhydryl-containing peptides and certain organic acids may form soluble Cd complexes. Although complexation of malate and oxalate with Cd is predicted to be less significant, citrate in the concentration range encountered in the tobacco cultured cell vacuoles has high potential for forming soluble complexes with Cd over the entire possible vacuolar pH range, especially 4.3 to 7.0, even in the presence of low levels of Cd-binding peptides. In addition, results show that inorganic chloride, sulfide (if present), and phosphate may also act to sequester Cd ion activity in the vacuole by forming soluble Cd-Cl and insoluble CdS and Cd-phosphate.

Journal Article↗
PubMed2006

Chlorine-35/37 NMR spectroscopy of solid amino acid hydrochlorides: refinement of hydrogen-bonded proton positions using experiment and theory.

Trends in the chlorine chemical shift (CS) tensors of amino acid hydrochlorides are investigated in the context of new data obtained at 21.1 T and extensive quantum chemical calculations. The analysis of chlorine-35/37 NMR spectra of solid L-tryptophan hydrochloride obtained at two magnetic field strengths yields the chlorine electric field gradient (EFG) and CS tensors, and their relative orientations. The chlorine CS tensor is also determined for the first time for DL-arginine hydrochloride monohydrate. The drastic influence of 1H decoupling at 21.1 T on the spectral features of salts with particularly small 35Cl quadrupolar coupling constants (CQ) is demonstrated. The chlorine CS tensor spans (Omega) of hydrochloride salts of hydrophobic amino acids are found to be larger than those for salts of hydrophilic amino acids. A new combined experimental-theoretical procedure is described in which quantum chemical geometry optimizations of hydrogen-bonded proton positions around the chloride ions in a series of amino acid hydrochlorides are cross-validated against the experimental chlorine EFG and CS tensor data. The conclusion is reached that the relatively computationally inexpensive B3LYP/3-21G* method provides proton positions which are suitable for subsequent higher-level calculations of the chlorine EFG tensors. The computed value of is less sensitive to the proton positions. Following this cross-validation procedure, /CQ(35Cl)/ is generally predicted within 15% of the experimental value for a range of HCl salts. The results suggest the applicability of chlorine NMR interaction tensors in the refinement of proton positions in structurally similar compounds, e.g., chloride ion channels, for which neutron diffraction data are unavailable.

Amino Acids↗
PubMed2001

Ion exchange chromatographic determination of olpadronate, phosphate, phosphite, chloride and methanesulfonic acid.

A method based on single column ion chromatography with UV detection was developed for purity testing and assay of monosodium olpadronate. The analyte aqueous solution is precipitated with methanol to enhance the impurities/olpadronate molar ratio, thus improving purity determination at trace levels. The resulting solution is injected into a standard chromatographic system with UV detector in indirect mode with a Waters IC Pak HR column using diluted nitric acid as the mobile phase. The method was fully validated according to ICH guidelines for the determination of phosphite, phosphate, chloride and methanesulfonic acid in olpadronate being suitable for purity testing and assay.

Chlorides↗
PubMed1958

Renal tubular transport of inorganic divalent ions by the aglomerular marine teleost, Lophius americanus.

A characterization was attempted of the mechanisms involved in the tubular transport of inorganic divalent ions by the aglomerular kidney of Lophius, attention being paid particularly to the possible existence of transport maxima (Tm) and to competition for transport among related substances undergoing tubular excretion. Excretory rates of divalent ions in non-treated fish during standard laboratory conditions paralleled spontaneous changes in urine flow. Tm rates of excretion were reached for magnesium, sulfate, and thiosulfate with corresponding plasma levels of 2 to 5, 5 to 17, and 4 to 12 microM/ml. respectively. Elevation of magnesium chloride levels in plasma markedly depressed calcium excretion; sodium thiosulfate similarly depressed sulfate excretion. Experimental observations suggest the existence of a transport system for divalent cations separate from another for divalent anions. Within each transport system the ion with the higher excretion rate depressed competitively transfer of the other ion. Neither system was influenced by probenecid (benemid) in doses which markedly depressed the simultaneous excretion rate of p-aminohippuric acid.

Animals↗
PubMed1997

C-type natriuretic peptide increases chloride permeability in normal and cystic fibrosis airway cells.

C-type natriuretic peptide (CNP), a hormone which stimulates particulate guanylate cyclase activity, was studied for its ability to stimulate chloride permeability through the cystic fibrosis transmembrane conductance regulator (CFTR) in airway epithelial cells. Two cell lines, Calu-3 and CF-T43, were used as models of normal and cystic fibrosis (CF) airway epithelial cells, respectively. Calu-3 cells, derived from a lung carcinoma, express relatively high levels of wild-type CFTR. CF-T43 is a transformed line derived from a nasal polyp and expresses the mutant CFTR, deltaF508. Calu-3 cells exposed to the nucleotide guanosine-3',5'-monophosphate (cGMP) analogue 8-Br-cGMP exhibit increased 36Cl- efflux, demonstrating that cGMP can mediate changes in chloride permeability. CNP induces a bumetanide-sensitive short circuit current across Calu-3 monolayers. Whole-cell currents stimulated by CNP display linear current-voltage relationships and have inhibitor pharmacology and ion selectivity consistent with CFTR channel activity. Sodium nitroprusside (SNP), an activator of soluble guanylate cyclase, and CNP both increase cGMP levels and short circuit current in Calu-3 cells. In contrast, exposure of CF-T43 cells to CNP resulted in an increased 36Cl- efflux rate only when combined with the adenylate cyclase agonist isoproterenol and the response was sensitive to kinase inhibitors. CF-T43 cells exposed to isoproterenol and SNP showed no increase in chloride efflux. Together, these data indicate that CNP can activate wild-type and mutant CFTR through a cAMP-dependent protein kinase pathway and that the sensitivity of Calu-3 cells for this stimulation is greater than that of the CF-T43 cells.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed2001

An environmental survey relating to improvised and emulsion/gel explosives.

The detection and identification of traces of inorganic ions and sugars can play a major role in the forensic investigation of an explosives related incident. This survey investigated the background levels of these substances in the general environment. Six sampling locations were selected from around the mainland of the United Kingdom, representing urban and rural sites. Swab and vacuum samples were collected from different locations within each site including motor vehicles, private houses, hotels, the exterior of buildings, road surfaces, and street signs. Sampling was carried out in summer and winter to investigate changes in the levels of the target species due to seasonal factors such as road treatments or weather. The samples were extracted with water and analyzed for a range of inorganic anions, cations, and sugars using ion chromatography. Most of the target anions were found to be common to all locations. Chloride, sulphate, nitrate, and phosphate were found to be the most common and the most abundant. Chlorate was found at a low level in some external samples. Perchlorate and thiocyanate were not detected in any samples. There was a marked increase in the quantity of sodium and chloride detected in samples collected during the winter. Sodium and calcium were detected in most samples. Potassium and magnesium were detected in approximately half of the samples. Ammonium was less common but detected at significant levels in wall samples. Glucose, fructose, and sucrose were detected in the vacuum samples from the interior surfaces of houses, hotels, and cars.

Journal Article↗
PubMed1975

Two forms of 4-aminobutyrate transaminase in guinea pig brain.

4-Aminobutyrate transaminase (GABA-T, 4-aminobutyrate alpha-oxoglutrate aminotransferase, EC 2.6.1.19) is an enzyme that inactivates the inhibitory neurotransmitter, GABA, but its pharmacological function is uncertain. Two forms of guiena pig brain GABA-T were isolated by DEAE-cellulose chromatography and designated as GABA-T-I and II, corresponding to an anionic and a cationic form. The enzymes were inhibited by high concentrations of a cationic form. The enzymes were inhibited by high concentrations of alpha-oxoglutrate (alpha-KG). Kinetic consists for GABA, when determined at pH 7.9 adn 1 mmol/l alpha-KG, were 0.74 mmol/l. GABA-T activity was inhibited by chloride and other anions. Kinetic analysis revealed chloride ion as a conpetitive inhibitor against GABA, but the Ki values differed among GABA-T-I and II (Ki equals 120 and 60 mmol/l, respectively). Similar degrees of difference were observed with acetate and lactate ion. These results suggest that GABA-T-II may regulate the GABA level in the inhibitory neurons and may play a similar functional role as that exhibited by monoamine oxidase in other synapses.

4-Aminobutyrate Transaminase↗
PubMed1992

[Results of multicenter evaluation of reagents for determination of sodium, potassium and chloride ions using enzyme activation].

We present the results of a multicentre evaluation with Boehringer Mannheim/Hitachi instruments of new "enzymatic" methods for the determination of Na+, K+, and Cl- in serum or plasma. The between-day coefficient of variation was less than 1.4% (Na+), less than 2.6% (K+) and less than 1.7% (Cl-). The linear range of the assays were at least 80 to 200 mmol/l (Na+), 1.5 to 17 mmol/l (K+) and about 30 to at least 200 mmol/l (Cl-). The comparisons with routine flame atomic emission spectrometry and coulometry showed a satisfactory agreement of the test results. The "enzymatic" assays are insensitive to even grossly elevated levels of bilirubin and lipids (sodium, potassium, and chloride assays), NH4+ (potassium assay) and amylase (chloride assay). Interference by various drugs was not detected. Since the new methods can easily be adapted to photometric clinical chemistry instruments, they represent a valuable alternative to the use of ion-selective electrodes, flame atomic emission spectrometry and coulometry.

Calibration↗
PubMed1983

Hydrogen ion secretion by the rat distal nephron: adaptation to chronic alkali and acid ingestion.

Isolated rat kidneys perfused at a low bicarbonate concentration were subjected to increased rates of buffer excretion, provided as creatinine, in order to examine the maximal hydrogen ion secretory capacity of the distal nephron. Preliminary experiments with kidneys from normal rats indicated that the quantity of hydrogen ion that titrated creatinine from urine pH to a pH of 6.0, designated TA-pH 6.0, provided an index of net hydrogen ion secretion by a functional segment of the distal nephron. With this technique the response of distal nephron hydrogen ion transport to ingestion of both acid and alkali loads was examined. Perfused kidneys from rats with chronic metabolic acidosis, produced by drinking 1.5% NH4Cl for 3-5 days, excreted urine with a lower pH and higher total titratable acid and TA-pH 6.0 than appropriate controls. Perfused kidneys from rats that ingested NaHCO3 for 7 days exhibited a higher urine pH and lower rates of total titratable acid and TA-pH 6.0 than controls. By contrast, kidneys from rats acutely tube-fed NaHCO3 3 h prior to study showed no change in urinary acidification parameters. Thus, chronic ingestion of an acid load stimulates, and chronic ingestion of an alkali load inhibits, the intrinsic hydrogen ion secretory capacity of the rat kidney at a distal nephron site. This intrinsic adaptation of the hydrogen ion transport mechanism is not secondary to changes in aldosterone because rats that ingested NaHCO3 chronically had higher plasma aldosterone levels than controls.

Acclimatization↗
PubMed1991

Quantification of plasma phenylethylamine by combined gas chromatography/electron capture negative ion mass spectrometry of the N-acetyl-N-pentafluorobenzoyl derivative.

An ultrasensitive method capable of detection and quantification of beta-phenylethylamine in 1 ml of human plasma has been developed using gas chromatography/electron capture negative ion mass spectrometry. Phenylethylamine and tetra-deutero phenylethylamine internal standard in plasma were acetylated, extracted into organic solvent and then further acylated with pentafluorobenzoyl chloride. The N-acetyl-N-pentafluorobenzoyl-phenylethylamines were detected by high-resolution single ion monitoring of the molecular ions. Normal plasma levels were found to be 41.5 +/- 10.7 pg ml-1, in accordance with results of a previous high-performance liquid chromatographic method.

Chromatography, Gas↗