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At least 19 recordsLinked to original sources
PubMed1978

Vinyl carbamate as a promutagen and a more carcinogenic analog of ethyl carbamate.

Vinyl carbamate was much more active (10 to 50 times) than ethyl carbamate for the initiation of skin tumors and for the induction of lung adenomas in mice. Vinyl carbamate was also mutagenic to Salmonella typhimurium TA 1535 and TA 100 in the presence of reduced nicotinamide adenine dinucleotide phosphate-fortified rat or mouse liver mitochondrial supernatant fractions. This mutagenic activity was inhibited strongly by cytochrome P-450 inhibitors. No mutagenic activity was observed for vinyl carbamate in the absence of added liver preparations or for ethyl carbamate in the presence or absence of liver fractions. Extensive tests with sensitive methods failed to detect vinyl carbamate as a metabolite of ethyl carbamate in the mouse in vivo. However, on administration of [ethyl-1-14C;1,2-3H]ethyl carbamate to adult mice the 3H/14C ratios of the hepatic DNA-, rRNA-, and protein-adducts were similar to each other and much lower than the ratio of the administered ethyl carbamate. These data are consistent with the presence of desaturated and/or oxidized ethyl groups in the macromolecular adducts. The qualitatively similar, but much stronger, carcinogenic activity of vinyl carbamate as compared to that of ethyl carbamate suggests that the metabolic pathways of these two carbamates may converge in the formation of similar or identical electrophilic reactants that bind covalently to macromolecules in vivo and initiate carcinogenesis.

Adenoma↗
PubMed1976

High-pressure liquid chromatographic determination of chlorphenesin carbamate and the beta-isomeric carbamate.

A high-pressure liquid chromatographic assay was developed for the determination of chlorphenesin carbamate and its beta-isomeric carbamate. A single 4-mm i.d. X 30-cm column, prepacked with 10 micrometer fully porous silica gel particles, is used with 3% methanol in 50% water-saturated butyl chloride as the mobile phase. The procedure separates chlorphenesin carbamate from several possible impurities in addition to the beta-isomeric carbamate. The assay was applied to bulk drug and compressed tablets. The relative standard deviations for the assays of chlorphenesin carbamate and the beta-isomer are approximately 1 and 2%, respectively.

Carbamates↗
PubMed1977

[A pharmacological study of chlorphenesin carbamate. Tolerance to chlorphenesin carbamate (author's transl)].

Tolerance to chlorphenesin carbamate (CPC) was investigated from the viewpoints of action of CPC, serum free CPC concentration, the activity of UDP-glucuronyltransferase and the content of cytochrome P-450. CPC was administered once daily for 7 or 14 days. In mice, the hypnotic action of hexobarbital injected 24 hours after the last administration of CPC and the motor incoordinating action of CPC significantly decreased on the 7th day, but slightly recovered on the 14th day. Serum free CPC concentration also decreased on the 7th day, but recovered on the 14th day. A significant relationship between the motor incoordinating action of CPC and serum free CPC concentration was observed. Therefore, the recovery of CPC effect on the 14th day was considered to be due to the recovery from the induction of drug-metabolizing enzymes. On the other hand, in rats, the weekly alteration of the motor incoordinating action of CPC was similar to that observed in mice. Serum free CPC concentration on the 7th and 14th days was lower than that on the 1st day, and enzyme induction was observed during CPC administration. Notwithstanding the low level of serum free CPC concentration, the recovery of CPC effect was observed on the 14th day and such was considered to be due to habituation to the rotarod. In mice and rats, it was demonstrated that the intensity of CPC effect was dependent on serum free CPC concentration to the extent that enzyme induction played an important role in the development of tolerance. From these results, the tolerance to CPC is attributed to induction of drug-metabolizing enzymes in liver microsomes.

Animals↗
PubMed1976

[Demonstration of the action of methyl benzimidazole 2 yl carbamate (MCB) and methyl(5(2 thienyl carbonyl) 1 H benzimidazole 2 yl carbamate) (R17934) on the nucleus of Physarum polycephalum (Myxomycetes)].

The toxicity of these compounds was determined in the amoebae and plasmodia. An electron microscopic study shows an increase in nuclear size which is in agreement with the increase of the total amount of DNA. Microtubules are present but they are not organized in a normal mitotic apparatus. Some other nuclear abnormalities are described.

Benzimidazoles↗
PubMed1976

The carbamate reaction of glycylglycine, plasma, and tissue extracts evaluated by a pH stopped flow apparatus.

We have used a stopped flow rapid reaction pH apparatus to investigate the carbamate equilibrium in glycylglycine solutions and in three biological tissues, human plasma, sheep muscle, and sheep brain, as well as to investigate the kinetics of carbamate formation in glyclyglycine solution and in human plasma. The rapid reaction apparatus was equipped with a pH sensitive glass electrode in order to follow the time course of pH from 0.005 to 100 s after rapid mixing of a solution of amine or protein and CO2. Two phases of the pH curve were observed: a fast phase representing carbamate formation, and a slow phase due to the hydration of CO2 which was uncatalyzed since a carbonic anhydrase inhibitor was added to the biological solutions. From the time course of pH change during the fast phase K2, the R-NH2 ionization constant, and Kc, the carbamate equilibrium constant as well as the velocity constant for the formation of carbamate, ka could be calculated from data at different pH and pCO2. The carbamate formed in glycylglycine solutions over a wide range of pH and pCO2 was found consistent with the theory of carbamate formation and with published data. At ionic strength 0.16 and 37 degrees pK is 7.67. pKc 4.58. The heat of the carbamate reaction (deltaH) was calculated to be -3.2 kcal/mol between 20 degrees and 37 degrees. Kt of glycylglycine depends quantitatively on ionic strength as predicted by the Debye-Huckel theory. With ionic strength 0.16 ku was found to be 2,500 M1 S1 at 37 degrees. The activation energy of carbamate formation is 6.7 kcal/mol. Carbamate measurements in human plasma at pCO2 from 38 to 359 Torr. pH from 6.9 to 8.3, temperature 37 degrees, and ionic strength 0.15 provided evidence that two kinds of amino groups participate in carbamate formation. From the equilibrium constants computed for the two species they could be identified as alpha- and epsilon-amino groups. On the basis of a protein molecular weight of 69.000. 0.6 alpha-amino groups/molecule with pKz=7.0 and pKc=4.2, and 5.9 epsilon-amino groups/molecule with pKz=9.0 and pKc=4.3 contribute to carbamate formation. The velocity constant ka was estimated to be 4,950 M1 S1 for the alpha-amino groups and 13,800 M1 S1 for the epsilon-amino groups. Under physiological conditions (pCO2=40 Torr. pH=7.4). The concentration of carbamate in plasma is 0.6 mM and the half-time of carbamate formation is 0.05 s. In extracts prepared from sheep brain at 37 degrees pH=7 and pCO2=35 Torr. the carbamate formation was estimated to be 0.8 mM. With pCO2=70 Torr and the same pH and temperature the carbamate concentration in muscle approximates 0.3 mM and increases to 7 mM as pH rises to 8. It is concluded that, as in plasma, a considerable number of epsilon-amino groups appear to be available for carbamate formation in these tissues.

Animals↗
PubMed1977

[Electroencephalographic effects of chlorphenesin carbamate, a new central muscle relaxant, in rabbits (author's transl)].

Electroencephalographic (EEG) effects of chlorphenesin carbamate were investigated in rabbits with chronic electrode implants, and compared with those of chlormezanone and methocarbamol. Chlorphenesin carbamate (50 mg/kg i.v., 100 mg/kg i.d.) induced a drowsy pattern of spontaneous EEG consisting of high voltage slow waves in the cortex and amygdala, and desynchronization of hippocampal theta waves. Chlormezanone also elicited similar EEG changes but such were much more potent than chlorphenesin carbamate. Methocarbamol showed no effect on spontaneous EEG. Chlorphenesin carbamate caused sedation in this period and muscle relaxation was more potent than that of chlormezanone. The EEG arousal response to auditory stimulation and to electric stimulation of the posterior hypothalamus, centromedian thalamus and mesencephalic reticular formation was slightly depressed by chlorphenesin carbamate. Chlorphenesin carbamate, as with chlormezanone, markedly depressed the limbic afterdischarges elicited by hippocampal stimulation. These EEG effects of chlorphenesin carbamate were qualitatively similar to but much weaker than those of chlormezanone, whereas the muscle relaxant effect of chlorphenesin carbamate was more potent than that of chlormezanone.

Acoustic Stimulation↗
PubMed1976

Carcinogenesis by carbamic acid esters and their binding to DNA.

The tumor-initiating potency of three simple alkyl carbamates and mono-N-substituted ethyl carbamates was examined in Hall strain mice. The binding of 14C-labeled carbamates of DNA was measured in Crackenbush mice. Ethyl carbamate was the most potent carcinogen for the epidermis, liver, and lung, followed by its N-alkyl derivatives. Methyl carbamate was without effect but n-propyl and n-butyl were possible carcinogens. The ethyl esters bound to a greater extent to DNA in liver and skin than the methyl, n-propyl, and n-butyl esters and only this binding persisted. A preliminary application of croton oil increased the yield of skin tumors but not of liver or lung tumors. It also increased the binding of the alkyl carbamates to DNA in skin, the increase being greatest with ethyl carbamate. The binding persisted longer in treated than in non-croton oil-treated mice.

Adenoma↗
PubMed1977

Vascular changes in the lungs of rats after the intravenous injection of pyrrole carbamates.

The effects on the lung of some synthetic compounds related to monocrotaline pyrrole have been studied and compared with those previously found with that compound. When injected into a systemic vein doses of pyrrole mono- and dicarbamate produced acute pulmonary oedema. Pyrrole alcohol and ethyl carbamate had no such effect and although furyl carbamate did not cause pleural effusion in rats it did so in mice. Like monocrotaline pyrrole, when injected into other vessels the pyrrole carbamates produced oedema in the region of the first capillary bed encountered. When colloidal carbon was injected intravenously after the pyrrole carbamates, carbon "labelling" was seen in both the post-capillary venules and the capillaries of the lungs. On the whole, venular "labelling" occurred before capillary "labelling" which was best seen when the carbon was injected more than 4 hr after the pyrrole. The distribution of the carbon as seen by electron microscopy is described. No "labelling" was seen after furyl carbamate. The effects of the synthetic pyrrole esters were similar to those of monocrotaline pyrrole. Although both the pyrrole carbamates were less active on a molecular basis they had a broader action on the pulmonary vasculature causing venular as well as capillary "labelling". To affect the lungs acutely the compound had to have the pyrrole ring structure and at least one ester side-chain.

Animals↗
PubMed1975

The carbamate equilibrium of bovine hemoglobin at 37 degrees C.

emoglobin-bound CO2 was estimated by a procedure first described by Rossi-Bernardi et al. (1969) in which the carbamate compound is stabilized by rapid mixing with alkali and then separated from other CO2 constituents in solution by gel filtration and ion-exchange chromatography. Carbamate equilibrium of bovine hemoglobin was studied at constant PCO2 (44 mm Hg) and varying pH as well as at constant pH (7.4) and varying PCO2 (ionic strength 0.18, temperature 37.0 degrees C). The difference in Z (deltaZ) between hemoglobin and oxyhemoglobin appeared to be 0.11 plus or minus 0.04 (pH=7.40; PCO2=44 mm Hg) i.e. about half the value observed in human hemoglobin. DeltaZ was shown to account completely for the difference in CO2 content (CCO2) between hemoglobin and oxyhemoglobin when in total equilibrium with CO2. Carbamate determinations on bovine hemoglobin specifically modified at all terminal amino groups (double-blocked carbamylated derivative) did not show any CO2 binding at all, thus giving a final proof for the exclusive role of the terminal amino groups in CO2 binding under physiological conditions. Attempts to calculate the ionization constant (Kz) and the carbamate equilibrium constant (Kc) of the terminal amino groups failed, suggesting that both terminal groups are not equivalent in their CO2 binding properties. This was confirmed by the fact that carbamate data obtained at constant PCO2 and varying pH fitted binding curves derived from two sets of independent but non-equivalent binding sites. Association constants for both kinds of binding sites appeared to differ by a factor of at least 3 in hemoglobin and of about 10 in oxyhemoglobin. From determinations of hemoglobin-bound CO2 and CO2 content of hemoglobin and oxyhemoglobin solutions in total equilibrium with CO2, the apparent first dissociation constant of carbonic acid was calculated as 5.71 plus or minus 0.0061 pH and found to be independent of the oxygenation state of hemoglobin. In contrast with hemoglobin of other species bovine hemoglobin appeared to be not influenced by the presence of 2.3-diphosphoglycerate as far as its CO2-binding properties are concerned.

Animals↗
PubMed1975

Analysis for carbamate insecticides and metabolites.

Of the more conventional pesticidal chemicals, the carbamate insecticides pose some unique problems relative to residue analysis. Most of these compounds are unstable under conditions normally used for GLC analysis and require special attention if this technique is to apply to the carbamates. Moreover, the carbamates are commonly metabolized to products which are toxicologically significant and which must be included in any analytical considerations. These and other problems inherent in carbamate residue methodology are discussed in this report along with technique currently utilized or having potential as sound procedures for the analyses of carbamate insecticides.

Acylation↗
PubMed1975

Pharmacokinetics and metabolism of two carbamate insecticides, carbaryl and landrin, in the rat.

1. A pharmacokinetic model for distribution of carbaryl and landrin (0-5 mg/kg) in male rat has been derived. Distribution of both compounds is adequately described in terms of two kinetically distinct compartments equilibrating slowly or rapidly with the blood circulatory system. The role of the slowly equilibrating tissue compartment is particularly important for carbaryl and as a result this carbamate has a longer half-life (77 min) than landrin (42 min). 2. Less than 1% of the carbamate was excreted unchanged. The kinetics of metabolism have been studied by decline in plasma carbamate concentrations, urinary excretion, and production of 14CO2 from the 14C-carbamyl group. Enterohepatic circulation of carbamate metabolites prolongs the duration of radioactivity in the body. 3. Comparison of different routes of administration shows that oral or hepatic portal administration results in lower plasma carbamate levels than those achieved by jugular vein injection, due to a liver first-pass effect.

Animals↗
PubMed1979

Studies on drug metabolism by use of isotopes. XXIV-Determination of 3-phenylpropyl carbamate metabolites using stable isotope labelling with deuterium or carbon-13.

Metabolism of 3-phenylproply carbamate was investigated by using a stable isotope tracer technique. 3-Phenylpropanol, 3-hydroxy-3-phenylpropanol, 3-hydroxy-3-phenylpropyl carbamate, 2,3-dihydroxy-3-phenylproply carbamate, benzoic acid and hippuric acid were identified as the rat urinary metabolites. Using the dilution analysis, the amounts of metabolites in urine and faeces in rat and man were determined. In rats, 2,3-dihydroxy-3-phenylproply carbamate and 3-phenylpropanol glucuronide were excreted into the urine as the major metabolites of this drug. On the other hand, in man, the major metabolite was hippuric acid and about 30% of the administered dose was excreted as hippuric acid in the 24 h urine. The tracer technique using a singly labelled drug with carbon-13 employed in the present study provided a reliable methods for the analysis of drug metabolites and was comparable with the tracer technique using a multilabelled drug with deuterium.

1-Propanol↗
PubMed1976

The effect of N-alkyl groups of substituted phenyl-N-alkyl carbamates on the inhibition of human plasma cholinesterase.

The inhibition constants for human plasma cholinesterase (dissociation, carbamylation, decarbamylation, overall bimolecular rate constants) were determined for two series of substituted phenyl-N-alkyl carbamates. N-propyl carbamates were found to be better inhibitors than the corresponding compounds carrying smaller N-alkyl groups. In both series the carbamylation constants of N-ethyl carbamates were lower than those of the N-methyl and N-propyl analogues, whereas the decarbamylation constants of the former were found to be higher than those of the latter carbamates. The experimental results obtained with human plasma cholinesterase are compared with published inhibition constants determined for several types of acetylcholinesterases.

Carbamates↗
PubMed1975

The excretion in urine of four insecticidal carbamates and their phenolic metabolites after oral administration to rats.

4 insecticidal carbamates: 3-methyl, 5-isopropylphenyl N-methyl-carbamate (Promecarb), 4-methylthio, 3,5 dimethylphenyl N-methylcarbamate (Mesurol), 4-dimethyl-amino, 3,5 dimethylphenyl N-methylcarbamate (Zectran), and 4-benzothienyl N-methyl-carbamate (Mobam) were orally administered to male Wistar rats. The excretion of the unchanged products was followed in 24 hrs urine collections. The corresponding phenols of the different carbamates could be identified as metabolites by gas-chromatography-mass spectrometyr. These metabolites were quantified afterward by gas-liquid chromatography. In all cases only minor quantities of unchanged products and metabolites were excreted in the urine over the 48 hrs after administration.

Administration, Oral↗
PubMed1979

[Determination of carbamate pesticides in fruits and vegetables by means of high pressure liquid chromatography (author's transl)].

It is shown that carbamate pesticides can be determined at the ppm level in different kinds of fruits and vegetables using high pressure liquid chromatography. The lower detection limit corresponding to a signal to noise ratio of three is between 0,025 and 0,25 ppm depending on the type of carbamate and plant material. In all cases it is below the maximum permissible value for pesticide residues. Due to the high separating power of high pressure liquid chromatography a simple sample pretreatment procedure can be used. The carbamates are extracted from the biological sample by dichloromethane and injected directly into the liquid chromatograph after replacing the extraction solvent by the mobile phase. In many cases a definite identification and quantitation of the carbamate is possible with a single chromatographic column. Some plants with a more complex matrix require a two-column operation in which the effluent fraction of the first column containing the pesticide is transferred by column switching to a second column in order to achieve a complete separation. The improved resolution in the two-column operation is caused by the relative enrichment effect of the fractionation and the increased column length.

Carbamates↗
PubMed1975

Uptake and excretion of organophosphorus and carbamate insecticides by fresh water fish, motsugo, Pseudorasbora parva.

Fresh water fish, Motsugo was reared in aquarium water tank containing about 1 ppm of 3 organophosphorus and 3 carbamate insecticides for about 30 days. The persistence of these insecticides in water and uptake and excretion of insecticides by fish were examined. Among organophosphorus insecticides, malathion is the most unstable in water, and degraded more than 99% for 7 days. Fenitrothion is moderately stable, and degraded 97% for 29 days. Diazinon is the most stable, and degraded 72% for 30 days. Among carbamates, carbaryl is the most unstable in water, and degraded more than 95% for 6 days. BPMC is moderately stable, and degraded 80% for 32 days. XMC is the most stable, and degraded 45% for 34 days. As for the uptake of the pesticides by fish, organophosphorus insecticides were generally higher than carbamate insecticides. The concentration of diazinon in fish reached to 211 ppm of the maximum level after 3 days, and that of fenitrothion reached to 162 ppm of the maximum level after 4 days. Afterwards, the concentration of both the insecticides decreased gradually due to the metabolism and excretion of the insecticides in fish. Uptake of malathion was very low and metabolized rapidly, and its concentration became to less than 0.01 ppm after 7 days. Among carbamate insecticides, the concentration of carbaryl in fish after one day reached to 7.5 ppm which was the maximum level of uptake. On the other hand, the concentration of BPMC in fish after 4 days became to 4.8 ppm, which was the maximum level, and decreased gradually. The concentration of XMC in fish was only 1.4 ppm after one day, but the metabolism rate of XMC in fish was fairly slow. Therefore, 0.55 ppm of XMC in fish remained even after 34 days. Moreover, in the test tank of diazinon, fenitrothion and BPMC, the appearance of deformed fish with spinal curvature of back bone came out at the rate of 10 to 30%.

Animals↗
PubMed1979

Direct gas chromatographic determination of carbamate pesticides using Carbowax 20M-modified supports and the electrolytic conductivity detector.

The gas chromatographic behavior of 32 carbamate pesticides was investigated using the Hall electrolytic conductivity detector. Relative retention indices were successfully determined for 24 carbamates on six different columns. Columns investigated included Ultra-Bond, 3% OV-101 on Ultra-Bond, 1% OV-17 on Ultra-Bond, 1% OV-210 on Ultra Bond, 1% Carbowax 20M on Ultra-Bond and 0.5% OV-210 + 0.65% OV-17 on Ultra-Bond. Chemical-ionization gas chromatography-mass spectrometry was used to verify that the carbamates were chromatographed intact. Chemical-ionization mass spectra are reported. Analytical procedures are demonstrated for the determination of carbamate residue in soil.

Carbamates↗