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At least 19 recordsLinked to original sources
PubMed1977

Letterflex photoprepolymer sensitization in newspaper printers due to penta erythritol tetrakis 3 mercaptopropionate and 3 mercaptopropionic acid.

The Letterflex urethane photopolymer mixture contains eight components. The curing agent penta erythritol-tetrakis-3 mercaptopropionate and an auxiliary substance present separately, namely 3 mercaptopropionic acid, gave positive reactions in five patients suffering from occupational contact allergic dermatitis. The mixture contains a third substance to which contact sensitization in a single patient has been described in the literature. This substance did not play any role in the patients' dermatitis. The ways in which the workers come into contact with the liquid form of the prepolymer, which is the sensitizing form of the mixture, are described. Safety measures and complete labelling are advised.

3-Mercaptopropionic Acid↗
PubMed1975

Ultrastructural and pharmacological studies on the afferent synapse of lateral-line sensory cells of the African clawed toad, Xenopus laevis.

Lateral-line sensory cells of Xenopus show considerable similarity to central nervous system synapses in their responses to the zinc iodide-osmium tetroxide, and bismuth-iodide cytochemical staining techniques. Both reserpine and FLA-63 cause a reduction in the diameter and electron density of the synaptic bars, and a dramatic loss of synaptic vesicles surrounding the bars. Aminooxy acetic acid and 3-mercaptopropionic acid cause no significant changes in the sensory-cell afferent synaptic apparatus. The results are discussed in the light of the known effects of the drugs. It is concluded that a monoamine rather than an amino acid may act as the afferent transmitter.

Aminooxyacetic Acid↗
PubMed1977

A new semiautomated fluorometric method for estimation of small amounts of L-dopa in human urine.

A semiautomated fluorometric method for the quantitative determination of urinary dopa, 3-(3,4-dihydroxyphenyl)-L-alanine, is described. It provides a simple, sensitive and reproducible analytical technique for routine use. Dopa is isolated from interfering substances, especially catecholamines, by adsorption onto aluminium oxide, elution with 0.1 M HCl, then passed through a cation-exchange column. By mild oxidation with potassium ferricyanide, dopa is cyclized to dopachrome. This is isomerised with strong alkali to 5,6-substituted indole, which is highly fluorescent but very unstable in the presence of oxygen. The addition of ascorbic acid and 3-mercaptopropionic acid to the alkaline solution stabilizes the fluorescence. Concentrations of chemicals, pH and reaction times are made optimal for maximal sensitivity. Recovery of dopa added to the urine samples averaged 79% (range, 75 to 83). Reproducibility of results from the same urine specimen gave a coefficient of variation of 2.4%. In healthy adults, we found daily excretion ranges from 17.3 to 54.9 (mean: 36.1) microng/24 h or from 0.015 to 0.048 (mean: 0.021) microng/mg cretinine.

Autoanalysis↗
PubMed1979

Metabolic inhibitors and subcellular distribution of GABA.

Experimental procedures are described which are believed to yield results that reflect, within certain limits, the in vivo changes of the size of the GABA pool in nerve endings in comparison with those of all other GABA pools. Two irreversible GABA-T inhibitors, vinyl GABA and acetylenic GABA, two GAD inhibitors, 3-mercaptopropionic acid and pyridoxal phosphate glutamyl-gamma-hydrazone, and di-n propylacetate, a clinically useful anticonvulsant, have been studied to determine their effects on GABA compartmentalization in mouse brain cortex. The changes elicited by these drugs in subcellular fractions of brain cortex homogenates support the notion that measurement of amino acid concentrations in crude synaptosomal fractions and in supernatant fractions under controlled conditions allow one to draw conclusions about relative changes of pool sizes in vivo. In particular this work showed that a specific increase in the concentration of GABA within the nerve endings is more important than a large increase of total brain GABA as a means of decreasing susceptibility to a variety of chemically or physically induced seizures.

3-Mercaptopropionic Acid↗
PubMed1979

Modification of orientation sensitivity of cat visual cortex neurons by removal of GABA-mediated inhibition.

The effects of an inhibitor of GABA synthesis, 3-mercaptopropionic acid (MP), and of the GABA antagonist bicuculline (BIC), on the direction and orientation sensitivity of visual cortical neurons were investigated using a computer-controlled stimulus presentation system. Intravenous administration of MP, which was usually more effective than if administered microelectrophoretically, induced a slight, but significant reduction in these properties of about half of the neurons tested. The effect of electrophoretic BIC was in the same direction but clearer than that of MP. In 71% of the simple cells, direction sensitivity was virtually lost during administration of BIC while orientation sensitivity was never completely eliminated in any neuron tested. Simultaneous administration of both drugs (MP systemically, BIC electrophoretically) caused more complete modification of the sensitivities than single administration of each. In four out of thirteen neurons tested, orientation sensitivity was completely abolished. The excitatory receptive fields slightly increased in size and became virtually round. The response magnitude to the optimal stimulus was increased by each drug along and by both. The present results further support the hypothesis that intracortical inhibition plays a major if not an exclusive role for the orientation and direction sensitivity of cortical cells.

3-Mercaptopropionic Acid↗
PubMed1977

[Hydrogen-adduct radicals in thymidine and thymidine 5'-monophosphate photosensitized by proflavin. Protection by sulfur compounds (author's transl)].

At pH values 5 and 9, the influence of cysteine, cystine, 3-mercaptopropionic acid and S-methylcysteine on the induction of H-adduct radicals in thymidine and thymidine 5'-monophosphate photosensitized by proflavin is investigated. The results obtained indicate that efficient protection is given when the electrostatic interactions between the charged groups of the molecules present allow the close proximity of a thiol or a disulfide bridge and the proflavin - DNAs complex constituent. The scheme proposed for the mechanism involves the capture by the protector of an electron or a proton, indispensable intermediates in the formation of the H-adduct radicals.

Acridines↗
PubMed1976

New coenzymically-active soluble and insoluble macromolecular NAD+ derivatives.

Reaction in dimethyl sulfoxide of nicotinamide 8-bromoadenine dinucleotide with the disodium salt of 3-mercaptopropionic acid afforded nicotinamide-8-(2-carboxyethylthio)adenine dinucleotide, a new NAD+ analogue functionalized at the adenine C-8 position by an omega-carboxylic side chain. Carbodimide coupling of the latter derivative to high-molecular-weight water-soluble (polyethyleneimine, polylysine) and insoluble (aminohexy)-Sepharose) polymers gave the corresponding macromolecular NAD+ analogues. These derivatives have been shown to be enzymically reducible. The polyethyleneimine analogue showed a substantial degree of efficiency relative to free NAD+ with yeast alcohol dehydrogenase (47%) but a considerably lower one with rabbit muscle lactate dehydrogenase (3%); the polylysine analogue showed a low degree of efficiency with both enzymes (5-6%).

Alcohol Oxidoreductases↗
PubMed1978

A new method of chemical modification of N6-amino group in adenine nucleotides with formaldehyde and a thiol and its application to preparing immobilized ADP and ATP.

Reaction of AMP with formaldehyde and 3-mercaptopropionic acid at pH 11.7 gave a new AMP derivative, N6-[(2-carboxyethyl)thiomethyl]-AMP (I) in 91% yield and reaction at pH 3.1 gave another new derivative, N6,N6-bis[(2-carboxyethyl)thiomethyl]-AMP (II) in 57% yield. The structures were determined by their 13C and 1H nuclear magnetic resonance spectra coupled with those of the simple analogues, N6-[(2-carboxyethyl)thiomethyl]-9-methyladenine (III) and N6,N6-bis[(2-carboxyethyl)thiomethyl]-9-methyladenine (IV) which were synthesized from 9-methyladenine in the same way as for derivatives I and II. ADP and ATP were treated in the same way as AMP to afford the corresponding carboxyl derivatives, N6-[(2-carboxyethyl)thiomethyl]-ADP (V), N6-[(2-carboxyethyl)thiomethyl]-ATP (VI), N6,N6-bis[(2-carboxyethyl)thiomethyl]-ADP (X) and N6,N6-bis[(2-carboxyethyl)thiomethyl]-ATP (XI) in 71%, 75%, 53% and 40% yield, respectively. These compounds were coupled to 1,3-diaminopropane with a water-soluble carbodiimide to give the corresponding amino derivatives, N6-([N-3-aminopropyl)carbamoylethyl]thiomethyl)-ADP (VIII), N6-(N-(3-aminopropyl)carbamoylethyl]thiomethyl)-ATP (IX), N6,N6-bis([N-(3-aminopropyl)carbamoylethyl]thiomethyl)-ADP (XIII), and N6,N6-bis([N-(3-aminopropyl)carbamoylethyl]thiomethyl)-ATP (XIV), which were further bound to CNBr-activated dextran to give new polymer-bound derivatives of ADP and ATP. These free and bo-nd derivatives were tested for their coenzymic activities against several kinases. The activities of the ADP derivatives, V, VIII, X, XIII, dextran-bound VIII, and dextran-bound XIII against acetate kinase were 82%, 81%, 68%, 55%, 35%, and 15%, respectively, relative to ADP and those of the ATP derivatives, VI, IX, XI, XIV, dextran-bound IX, and dextran-bound XIV against hexokinase were 88%, 94%, 60%, 81%, 58%, and 49%, respectively, relative to ATP.

Adenosine Diphosphate↗
PubMed1978

Possible role of gamma-aminobutyric acid synthesis in the mechanism of dexamethasone feedback action.

Specific inhibition of glutamic acid decarboxylase (GAD, EC 4.1.1.15; the main enzyme involved in the synthesis of gamma-aminobutyric acid) by mercaptopropionic acid interferes with the effect of dexamethasone on both the resting and stress-induced secretion of ACTH. It is postulated that dexamethasone may, at least in part, inhibit the secretion of ACTH via the induction of GAD, thereby raising the level of gamma-aminobutyric acid in the central nervous system.

3-Mercaptopropionic Acid↗
PubMed1979

A novel orally active converting-enzyme inhibitor YS 980: effects on blood pressure in spontaneously hypertensive rats.

1. The effects of long-term treatment with the angiotensin I converting-enzyme inhibitor YS 980 were examined in stroke-prone spontaneously hypertensive (sp-SH) rats. Development of hypertension was markedly blunted in the YS 980-treated animals. 2. Effective converting-enzyme inhibition was confirmed by significant increases in plasma angiotensin I (ANG I) and plasma renin concentration, inhibition of the pressor responses to intravenous ANG I and potentiation of the depressor responses to intravenous bradykinin. 3. Urinary free aldosterone excretion was decreased but no changes in urinary sodium and potassium excretion were observed. 4. The pressor responses to intravenous leucine-enkephalin were reduced. 5. The pressor responses to injection of ANG I and bradykinin into the lateral brain ventricle were unaltered. 6. We conclude that the antihypertensive action of YS 980 in sp-SH rats cannot be explained by the inhibition of the plasma renin-angiotensin system alone. Effects on other peptide systems must be considered.

3-Mercaptopropionic Acid↗
PubMed1977

Allergic contact dermatitis to a photopolymerizable resin used in printing.

Organic photopolymerizable resins increasingly used in printing make it possible to produce flexible, lighter plates. A certain number of skin lesions and general symptoms appeared upon manipulation of plates made by the Letterflex process. In the workshop where this study was carried out, 12 out of 15 people suffered various degrees of skin lesions. The epicutaneous tests and biopsies performed indicate an allergic type reaction to one of the resin's constituents, polythiol. Experiments with animals confirm the strong allergenicity of this compound.

3-Mercaptopropionic Acid↗