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Results for “Vinyl Compounds”

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At least 739 records · Page 41Linked to original sources
PubMed1980

Characteristics of haloethylene-induced acetonemia in rats.

A series of halogenated ethylenes (vinyl chloride, vinylidene fluoride, cis- and trans-1,2-dichloroethylene, perchloroethylene) induces increased acetone exhalation in rats. Exposures of differently pre-treated rats to vinylidene fluoride suggest that a metabolite of the haloethylene must be envolved in eliciting this formation of acetone. This conclusion is based on (a)dependence of acetone exhalation on the concentration of vinylidene fluoride, (b)effect of inducing agents, (c)effect of pyrazol, a metabolic inhibitor, (d)effect of cysteine, (e)effect of hypoxia and (f)the time course of acetone exhalation.

Acetone↗
PubMed1984

Vinyl chloride-induced hepatic coproporphyrinuria with transition to chronic hepatic porphyria.

A chronic hepatic disorder of porphyrin metabolism was found in 36 workers with vinyl chloride (VC)-induced hepatic injury following long-time industrial exposure. Pathologic porphyrinuria, especially secondary coproporphyrinuria with transition to subclinical chronic hepatic porphyria, is a consistent pathobiochemical parameter for the recognition of VC hepatic lesions. The porphyrinuria is of diagnostic value for the incipient toxic phase. Erythrocyte uroporphyrinogen decarboxylase activity studied in six cases with initial chronic hepatic porphyria was normal, suggesting that VC affects only this enzyme in the liver.

Chemical Industry↗
PubMed1985

[Vinyl chloride induced hepatocellular carcinoma].

On the occasion of a hitherto unique observation of three hepatocellular carcinomas in workers of the same industrial plant within 7 years following long-term exposure to vinylchloride, the characteristics are discussed of a chemical carcinogenesis leading to two different malignant tumours: haemangiosarcoma and hepatocellular carcinoma. This carcinogenic sequence has been predicted by animal studies. It is not known why the transformation of hepatocytes into carcinoma is far rarer than of sinusoidal cells into sarcoma. Whereas the hepatocellular carcinoma predominantly develops in association with cirrhosis, vinyl chloride is able to cause cancer directly without other known co-carcinogenic agents. This hepatic carcinogenicity is dose-dependent. After the introduction of industrial prevention measures, a new initiation of the tumour is improbable. Nevertheless, because of its long latency period, estimated between 5 and 20 years, clinical manifestations are still possible. An early diagnosis by sonography and computertomography, possibly combined with puncture, in exposed persons or those formerly at high risk is conceivable, while laboratory data, even tumour markers are unreliable. Its fulminant course does not differ from that of other hepatocellular carcinomas and has until now hindered successful treatment.

Aged↗
PubMed1995

Probing a functional role of Glu87 and Trp89 in the lid of Humicola lanuginosa lipase through transesterification reactions in organic solvent.

To reveal the functional role of Glu87 and Trp89 in the lid of Humicola lanuginosa lipase, site-directed mutagenesis at Glu87 and Trp89 was carried out. The catalytic performance of wild-type and mutated lipases was studied in transesterification reactions in cyclohexane at a controlled water activity. Two different acyl donors were used in the investigation: tributyrin, a natural substrate for a lipase, and vinyl butyrate, an activated ester suitable for fast and efficient lipase-catalyzed transformations in preparative organic synthesis. As acyl acceptor 1-heptanol was used. The Glu87Ala mutation decreased the Vmax,app value with tributyrin and vinyl butyrate by a factor of 1.5 and 2, respectively. The Km,app for tributyrin was not affected by the Glu87Ala mutation, but the Km,app for vinyl butyrate increased twofold compared to the wild-type lipase. Changing Trp89 into a Phe residue afforded an enzyme with a 2.7- and 2-fold decreased Vmax,app with the substrates tributyrin and vinyl butyrate, respectively, compared to the wild-type lipase. No significant effects on the Km,app values for tributyrin or vinyl butyrate were seen as a result of the Trp89Phe mutation. However, the introduction of a Glu residue at position 89 in the lid increased the Km,app for tributyrin and vinyl butyrate by a factor of > 5 and 2, respectively. The Trp89Glu mutated lipase could not be saturated with tributyrin within the experimental conditions (0-680 mM) studied here. With vinyl butyrate as a substrate the Vmax,app was only 6% of that obtained with wild-type enzyme.

Binding Sites↗
PubMed1990

Stability of somatostatin in total parenteral nutrition.

The stability of somatostatin, added to a total parenteral nutrition formula, in glass containers and in plastic ethylene vinyl acetate containers was investigated. The somatostatin concentration decreased immediately from 3 micrograms/ml to 0.3-0.6 micrograms/ml after addition to the emulsion. In spite of this rapid decrease, somatostatin concentrations remained stable with values of 0.4-0.7 micrograms/ml during the follow-up period (24 h). These findings could be explained assuming adsorption to the surface of the container.

Drug Packaging↗
PubMed1977

The Environmental fate of three carcinogens: benzo-(alpha)-pyrene, benzidine, and vinyl chloride evaluated in laboratory model ecosystems.

Radiolabeled benzo-((alpha)-pyrene, benzidine, and vinyl chloride were evaluated in laboratory model ecosystems for environmental fate, degradation pathways, bioconcentration, and food chain accumulation. The comparative effects of microsomal detoxications were evaluated using the inhibitor piperonyl butoxide. The accumulation and bioconcentration of benzo-(alpha)-pyrene and benzidine were closely correlated with their octanol/water partition coefficients and water solubility. Benzo-(alpha)-pyrene as predicted by these parameters was bioaccumulated to substantial levels in several organisms. Vinyl chloride was not accumulated because of its high volatility.

Animals↗
PubMed1977

Electron microscopic observation of the liver in portal hypertension following chronic exposure to vinyl chloride monomer.

Two patients with portal hypertension following chronic exposure to vinyl chloride monomer were studied histologically and ultrastructurally. Both cases showed non-cirrhotic portal hypertension accompanied by esophageal varices and splenomegaly. They proved hepatic fibrosis with conventional microscope. Ultrastructurally, there were large amounts of small myelin-like lamellar materials with electron density and remarkable proliferation and vesiculation of smooth endoplasmic reticulum in the cytoplasms of hepatocytes. The widened Disse's spaces, were the sinusoidal lining cells were arranged in multilayers, were plugged by collagenous fiber bundles. The finding may be consistent with the development of portal hypertension.

Adult↗
PubMed2006

Evaluation of anticancer activity of 4-vinyl-1-arylsulfonylimidazolidinones.

To continue exploration of structure activity relationship of novel 1-(indoline-5-sulfonyl)-4-phenylimidazolidinones (1) reported as anticancer agent with broad spectrum, three 1-(arylsulfonyl)-4-vinylimidazolidinones (2) were synthesized from methyl serinate (3) in 8 steps. Reaction of intermediate 2-phenoxycarbonylaminobut-3-enyl p-toluenesulfonate (10) with arylsulfonamide in the presence of potassium carbonate produced corresponding 2 and N-(4-vinyloxazolidin-2-yl)arylsulfonamide 11 in approximately equal ratio. This reaction is believed to undergo through urea intermediate 16 as shown in scheme 3. 1-Arylsufonyl-4-vinylimidazolidinones 2 show much reduced activity against human colon carcinoma (Colo205), human chronic myelogenous leukemia (K562), and human ovarian adenocarcinoma (SK-OV-3) and compatible activity against human lung carcinoma (A549) compared to 1. Therefore phenyl at 4-position should be the optimum planar motif for the activity of 1.

Antineoplastic Agents↗
PubMedDate not supplied

Bioavailability and bioequivalence of etonogestrel from two oral formulations of desogestrel: Cerazette and Liseta.

In a three-period cross-over study with 24 healthy young females (study part 1), the bioavailability of etonogestrel (3-ketodesogestrel) was determined after a single oral dose of two Cerazette tablets (each containing 75 microg desogestrel), one Liseta tablet (containing 150 microg desogestrel and 1.5 mg 17beta-estradiol), and an intravenous dose of 150 microg etonogestrel. Etonogestrel serum levels from 23 subjects could be analysed by radio-immunoassay. The geometric mean bioavailability of etonogestrel from Cerazette and Liseta tablets was 0.79 and 0.82, with 95% confidence intervals of 0.73-0.86 and 0.76-0.88, respectively. Also, the oral formulations were found to be bioequivalent. Subsequently, the single-dose pharmacokinetic parameters of etonogestrel from Cerazette tablets were compared with those after multiple dosing of one Cerazette tablet once daily for 7 days, in a subgroup of 12 subjects (study part 2). A steady state was observed from the fourth day of daily dosing onwards, with time-invariant parameters except for a 14% lower dose-normalised AUC. The least-squares geometric means of the elimination half-life of etonogestrel were approximately 30 h for the three single-dose treatments in study part 1, as well as for the single- and multiple-dose treatments of Cerazette in study part 2, without differences between groups.

Administration, Oral↗
PubMed2003

Sulfonated and sulfoacylated poly(styrene-divinylbenzene) copolymers as packing materials for cation chromatography.

Three different types of cation exchangers were produced from four basic poly(styrene-divinylbenzene) substrates with different properties. Porous PS-DVB resin beads were functionalized by sulfonation and sulfoacylation under various conditions to produce sulfonated resins with exchange capacities of 0.03-1.80 mM g(-1). The matrix with 50% of cross-linking is most suitable for updating by the proposed technique. Sulfuric and chlorosulfonic acids were used as the reagents for sulfonation. The sulfonating conditions, capacities, and the technique of the synthesis are given. The effects of parameters of the sulfonation reaction and the composition of the reactionary mixture on ion-exchange capacity of the sorbents were investigated. Selectivity and efficiency of the separation of some inorganic cations and derivatives of amines and hydrazines on the resins obtained are compared by ion chromatography with conductometric detection. As a result, the sulfoacylated resin was proved more efficient for the separation of these analytes. The resolution of the analytes strongly depends on the degree of functionalization. The best performance about 19,000 plates m(-1) was obtained using the sulfopropionylated beads with an ion-exchange capacity of 0.3 mM g(-1). The prepared sulfoacylated cation exchanger was compared with the commercially available Dionex CS-12 packing material. It was found that the separation of alkaline ions and 1,1-dimethylhydrazine (UDMH) were much better that those for the commercial material.

Alkanesulfonates↗
PubMed2003

Enantioselective transesterification using lipase-displaying yeast whole-cell biocatalyst.

An enantioselective transesterification in non-aqueous organic solvent was developed by utilizing a lipase-displaying yeast whole cell biocatalyst constructed in our previous study. As a model reaction, optical resolution of (RS)-1-phenylethanol, which serves as one of chiral building blocks, was carried out by enantioselective transesterification with vinyl acetate. Recombinant Rhizopus oryzae lipase displayed on the yeast cell surface retained its activity in hexane, heptane, cyclohexane and octane. The effective amount of whole-cell biocatalyst in the reaction mixture was 10 mg/ml solvent. In a reaction mixture incubated for 36 h with molecular sieves 4A, the concentration of (R)-1-phenylethyl acetate reached 39.8 mM (97.3% yield) with high enantiomeric excess (93.3%ee). In contrast, a reaction mixture incubated without molecular sieves 4A produced little (R)- and (S)-1-phenylethyl acetate. The results obtained in this study demonstrate the applicability of the lipase-displaying yeast whole cell biocatalyst to bioconversion processes in non-aqueous organic solvents.

Benzyl Alcohols↗