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PubMed1978

The effect of clofibrate and pyridinol carbamate on the circulating immune complexes and cellular immune response in experimental atherosclerosis.

Cholesterol-fed rabbits were treated with clofibrate, pyridinol carbamate and with both drugs simultaneously. The quantity of circulating immune complexes in the sera of the animals was measured weekly and the migration inhibition test was carried out in the 12th week of the experiment. The trend of the changes in the concentration of the immune complexes was rather similar to that of the cellular immune response. Compared with the values obtained in the control animals, in the cholesterol-fed group a markedly higher level of immune complexes and a significant migration inhibition could be detected. The administration of clofibrate or pyridinol carbamate alone had no effect on the concentration of immune complexes. Pyridinol carbamate did not influence the migration inhibition; however, it became similar to the healthy controls in the clofibrate-treated group. Simultaneous treatment with both drugs resulted in a decrease in the quantity of immune complexes and a diminution of the migration inhibition.

Animals↗
PubMed1995

Effects of benzofuran and seven benzofuran derivatives including four carbamate insecticides in the in vitro porcine brain tubulin assembly assay and description of a new approach for the evaluation of the test data.

The influence of benzofuran and 7 benzofuran derivatives, including the carbamate insecticides benfuracarb, carbofuran, carbosulfan, and furathiocarb, on the in vitro assembly kinetics of porcine brain tubulin was investigated. A new approach to the evaluation of the raw data was made based on polynomial regression and the calculation of a polynomial function of the 11th degree fitting the raw data. By this procedure it is possible to calculate the parameters defining the shape of the absorbance curves and more parameters than those used so far can be included in the analysis of substance effects. In detail, the following curve parameters of the dependence of optical absorption on time were included in the evaluation of the substances of interest: the difference between maximum and minimum absorbance as a measure for the polymerization degree, the coordinates of the turning point of the curve, the slope of the tangent at the turning point which represents the maximum reaction velocity, the mean slope between the points with 10% absorbance increase and 90% absorbance increase and the duration of the lag phase. Out of the eight compounds tested, only the carbamate insecticides had distinct effects on the in vitro polymerization of tubulin, whereas benzofuran and the three 2,3-dihydro-2,2-dimethylbenzofuran derivatives without a carbamate function were inactive. Benfuracarb, carbofuran, carbosulfan, and furathiocarb led to a dose-dependent reduction of the polymerization degree of tubulin as well as to reduction of the maximum and mean reaction velocities. The strongest effects were obtained with furathiocarb and benfuracarb.

Animals↗
PubMed1987

Thirteen-week oral toxicity study of methyl carbamate in rats and mice.

The purpose of this study was to identify the toxicologic effects produced by methyl carbamate in F344 rats and B6C3F1 mice. Administration of methyl carbamate by gavage five times a week for 13 weeks to male (50, 100, 200, 400, or 800 mg/kg) and female (62.5, 125, 250, 500, or 1000 mg/kg) rats resulted in dose-related lesions in the liver characterized by proliferative changes in hepatocytes consisting of foci of cellular alteration and frequent mitoses with atypical forms. Toxic alterations consisted of focal hepatocellular necrosis, pigmentation of Kupffer's cells, and the presence of basophilic inclusions resembling nucleoli in the cytoplasm of hepatocytes. Other toxic effects observed in rats were weight loss, testicular hypoplasia, bone marrow hyperplasia, and excessive pigmentation of the spleen. The survival of male and female rats was reduced following administration of the highest dose of methyl carbamate. In contrast to these findings, administration of the chemical to male (93.75, 187.5, 375, 750, or 1500 mg/kg) and female (125, 250, 500, 1000, or 2000 mg/kg) mice five times a week for 13 weeks resulted only in weight loss and inflammatory changes of the liver. The proliferative nature of the hepatic lesions observed in rats suggests that the compound is potentially hepatocarcinogenic.

Administration, Oral↗
PubMed1990

High performance liquid chromatographic method for the analysis of organophosphorus and carbamate pesticides.

A method has been developed for the rapid quantitative analysis of organophosphorous and carbamate pesticides using HPLC. Good separation was obtained among the four major groups of organophosphorus pesticides [i.e. aryl phosphorothionate (methyl parathion), alkyl phosphorothionate (malathion), enolphosphate (phosphomidon, monocrotophos, dichlorvos), heterocyclic phosphorothionates (quinalphos)] and carbamates [viz. Carbaryl (Sevin) and Baygon (Dalf)] with a detection limit of 100 ng for all the pesticides. Separation was measured in terms of capacity factor (k') resolution (R) and selectivity factor (alpha ii). The method described can be used for the analysis of biological samples for the presence of organophosphorus and carbamate pesticides in the cases of poisoning. Recovery studies were made in the blood, lung and liver and found to be 85-97% with reproducibility at greater than 95%.

Autopsy↗
PubMed1990

Positive- and negative-ion mass spectrometry and rapid clean-up of some carbamate pesticides.

Positive-ion electron impact (PIEI), positive-ion chemical ionization (PICI) and negative-ion chemical ionization (NICI) mass spectra of 9 carbamate pesticides are presented. In the PIEI mode, the spectra showed small molecular peaks, intense or base peaks due to M - CH3NHCO + H and peaks at m/z 58 due to CH3NHCO. In the PICI mode, peaks due to M + H, M + C2H5, M - CH3NHCO + 2H, CH3NHCO(m/z 58) and M-28 appeared. The cations at m/z 58 found in both PIEI and PICI modes seem very useful for screening of a carbamate. In the NICI mode, the spectra showed peaks due to M - CH3NHCO and characteristic anions appearing at mass numbers higher than molecular ones, which were probably due to dimerization of [M - CH3NHCO]-followed by hydrogen attachment. Carbamates, which had been added to urine, plasma, whole blood, the liver, kidney and brain, could be rapidly isolated by use of Sep-Pak C18 cartridges with chloroform as an elution solvent. They could be detected by wide-bore capillary gas chromatography with a SPB-5 column, with satisfactory separation from impurities in their underivatized forms.

Body Fluids↗
PubMed1990

Pralidoxime in the treatment of carbamate intoxication.

The use of oxime reactivators of inhibited cholinesterase enzymes in poisoning by carbamate compounds has received mixed reviews in the medical literature. Data are limited and inconsistent on the possible role oxime reactivators might have in carbamate intoxication. Based on existing experience, atropine remains the treatment of choice and pralidoxime (2-PAM) is not recommended except in cases where atropine has first been proven inadequate, in serious mixed poisonings with both carbamate and organophosphorus compounds, or in serious poisonings by unidentified cholinesterase inhibitors.

Atropine↗
PubMed1992

Synthesis, receptor binding and target-tissue uptake of carbon-11-labeled carbamate derivatives of estradiol and hexestrol.

Carbon-11-labeled estradiol and hexestrol derivatives were prepared via the reaction of [11C]ethylchloroformate with the 2- and 4-amino derivatives of estradiol, the 3'-amino derivatives of hexestrol, and the 1-aminophenoxy derivatives of hexestrol and 1-norhexestrol. The corresponding nonradioactive carbamates were prepared for chemical characterization and in vitro receptor binding assays. The positions of the substituents on the parent molecules were selected with a view to minimize interference with the receptor binding process. In spite of this, affinity for the estrogen receptor was strongly impaired for all carbamate derivatives. Likewise, in vivo, the [11C]carbamate analogs failed to localize in receptor rich tissue via an estrogen receptor mediated process.

Amines↗
PubMed2005

Structure-based design of 7-carbamate analogs of geldanamycin.

The 7-carbamate groups of geldanamycin and its 17-(2-dimethylaminoethyl)amino-17-demethoxy derivative (17-DMAG) bind the N-terminal domain of Hsp90 by establishing a network of hydrogen bonds which involve four buried water molecules. In this study, a structure-based approach was used to investigate the effects of displacing some of these waters by modification of the 7-carbamate. A general loss of binding to human Hsp90 was observed, except for replacement of the carbamate with a hydroxamate group which gave an analog with weak activity. Modeling of Hsp90-ligand interactions suggested that the hydroxamate was not able to displace the buried water molecules, while bulkier substituents able to do so proved inactive.

Benzoquinones↗
PubMed2006

Synthesis and transdermal penetration-enhancing activity of carbonic and carbamic acid esters--comparison with transkarbam 12.

Transkarbam 12 (T12) is a novel transdermal penetration enhancer with high activity. Its polar head group is formed by carbamic acid salt that is unstable in acidic environment and releases CO(2). To find out whether this property influences its high activity, two series of compounds with CO(2) stronger bound in the polar head have been prepared-carbonic and carbamic acid esters. The carbamate salt in the polar head was found to be essential for the enhancing activity and its decomposition in an acidic environment suggested relating to the mode of action of T12.

Administration, Cutaneous↗
PubMed2006

Inhibitory effects of four carbamate insecticides on acetylcholinesterase of male and female Carassius auratus in vitro.

The inhibitory effects of four carbamate insecticides, methomyl, thiodicarb, carbofuran and carbosulfan, on acetylcholinesterase of male and female Carassius auratus were investigated in the laboratory. Kinetic constants, biomolecular rate constant (k(i)), carbamylation rate constant (k2) and decarbamylation rate constant (k3) were determined in vitro. The ratios of bimolecular rate constant (female/male) for AChE reacting with methomyl, thiodicarb, carbofuran and carbosulfan were 1.03, 2.44, 1.03 and 1.106, respectively. The k(i) of AChE for thiodicarb was significantly higher in female fish than in male fish (P<0.05). The ratios of carbamylation rate constant (female/male) for methomyl, thiodicarb, carbofuran and carbosulfan were 1.18, 4.29, 3.53, and 2.07, respectively. The k2 values of AChE for the above four carbamates were significantly higher in females than in males. The ratios of the decarbamylation rate constant (female/male) for methomyl, thiodicarb, carbofuran and carbosulfan were 1.02, 1.39, 1.06, and 1.98, respectively. Only for carbosulfan, the decarbamylation rate of AChE was significantly higher in the female than in the male, indicating that AChE of females inhibited by carbosulfan recovered more quickly than that of males. The above results suggest that the female in the sensitivity of AChE to carbamates was different from the male fish.

Acetylcholinesterase↗
PubMed2006

Application of liquid-phase microextraction and on-column derivatization combined with gas chromatography-mass spectrometry to the determination of carbamate pesticides.

A method has been established for the determination of five carbamate pesticides in water samples using liquid-phase microextraction (LPME) followed by on-column derivatization and gas chromatography-mass spectrometric (GC-MS) determination. Trimethylphenylammonium hydroxide (TMPAH) and trimethylsulfonium hydroxide (TMSH) were used as derivatization reagent for extracts prior to GC-MS analysis as carbamate pesticides are thermally labile compounds. Parameters that affect the extraction efficiency (selection of organic solvent and extraction time) and derivatization efficiency (choice of derivatization reagent and concentration of derivatization reagent) were investigated. The proposed method provided good enrichment factors up to 224, with reproducibility ranging from 4.86 to 7.81%, and good linearity from 1 to 400 microg/L. The limits of detection (LODs) ranged between 0.2 and 0.8 microg/L (S/N = 3) using GC-MS with selective ion monitoring. This method was applied to the determination of carbamate pesticides in tap water and waste water.

Carbamates↗
PubMed2006

Differential responses of eight cyanobacterial and green algal species, to carbamate insecticides.

In this study, five carbamate insecticides were subjected to 96 h acute toxicity tests to examine their effects on three cyanobacteria, Anabaena flos-aquae, Microcystis flos-aquae, and Mirocystis aeruginosa, and five green algae, Selenastrum capricornutun, Scenedesmus quadricauda, Scenedesmus obliquus, Chlorella vulgaris, and Chlorella pyrenoidosa. The average acute toxicity of the carbamate insecticides to the cyanobacteria and the green algae was in descending order carbaryl>carbofuran, propoxur, metolcarb > carbosulfan. Wide variations in response to the tested carbamate insecticides occurred among the eight individual species of cyanobacteria and green algae. The sensitivity of various species of algae exposed to carbofuran, propoxur, metolcarb, and carbaryl varied over one order of magnitude, and that of algae exposed to carbosulfan varied over two orders of magnitude. With regard to the diffrential sensitivity of cyanobacteria and green algae, the cyanobacteria were less sensitive than green algae to carbosulfan and propoxur. The pollutants may initiate a shift of algal group structure; especially, a shift from dominance by green algae to dominance by cyanobacteria, and may sustain cyanobacterial blooms at particular times. Therefore, the descending order of the ecosystem risk was carbosulfan > propoxur > carbofuran > carbaryl, metolcarb. There was a strong variance between toxicity and ecosystem risk; i.e., "low toxicity" does not imply "low ecosystem risk."

Carbamates↗
PubMed2005

Differential effects of TAK-802, a selective acetylcholinesterase inhibitor, and carbamate acetylcholinesterase inhibitors on contraction of the detrusor smooth muscle of the guinea pig.

The aim of this study was to compare the effects of TAK-802, a novel acetylcholinesterase (AChE) inhibitor, and carbamate AChE inhibitors on the detrusor smooth muscle contractility in vitro using isometric tension measurements. The effects of drugs on the nicotine-induced contractions and basal tone of the isolated detrusor muscle of the guinea pig were examined. All of the drugs, namely, TAK-802, distigmine, neostigmine and pyridostigmine, enhanced the nicotine-induced contractions of the muscle strips in a concentration-dependent manner. On the other hand, while neostigmine and pyridostigmine markedly increased the basal tone, and distigmine slightly but significantly increased the basal tone, TAK-802 had no influence on the basal tone of the muscle strips at all. However, following co-treatment with tetraisopropyl pyrophosphoramide, a selective butyrylcholinesterase (BuChE) inhibitor, TAK-802 also did increase the basal tone. The increase of the basal tone by all of the above treatments was completely abolished by atropine. These results reveal that while all the four AChE inhibitors enhanced endogenous acetylcholine-induced contractions, their effects on the basal tone were clearly different. The effect of carbamate AChE inhibitors of increasing the basal tone could be partly attributed to their dual inhibition of both AChE and BuChE, because both cholinesterases may play a critical role in maintaining the resting tension of the urinary bladder. TAK-802, however, did not increase the basal tone of the detrusor muscle strips, probably because of its selective inhibitory effect against AChE. The effect of carbamate AChE inhibitors on the basal tone of the detrusor muscle may explain the decrease of bladder compliance observed in our previous study on guinea pigs as well as the deterioration of the bladder-storage function reported with their clinical use.

Acetylcholinesterase↗
PubMed2004

Age dependence of organophosphate and carbamate neurotoxicity in the postnatal rat: extrapolation to the human.

One important aspect of risk assessment for the organophosphate and carbamate pesticides is to determine whether their neurotoxicity occurs at lower dose levels in human infants compared to adults. Because these compounds probably exert their neurotoxic effects through the inhibition of acetylcholinesterase (AChE), the above question can be narrowed to whether the cholinesterase inhibition and neurotoxicity they produce is age-dependent, both in terms of the effects produced and potency. The rat is the animal model system most commonly used to address these issues. This paper first discusses the adequacy of the postnatal rat to serve as a model for neurodevelopment in the postnatal human, concluding that the two species share numerous pathways of postnatal neurodevelopment, and that the rat in the third postnatal week is the neurodevelopmental equivalent of the newborn human. Then, studies are discussed in which young and adult rats were dosed by identical routes with organophosphates or carbamates. Four pesticides were tested in rat pups in their third postnatal week: aldicarb, chlorpyrifos, malathion, and methamidophos. The first three, but not methamidophos, caused neurotoxicity at dose levels that ranged from 1.8- to 5.1-fold lower (mean 2.6-fold lower) in the 2- to 3-week-old rat compared to the adult. This estimate in the rat, based on a limited data set of three organophosphates and a single carbamate, probably represents the minimum difference in the neurotoxicity of an untested cholinesterase-inhibiting pesticide that should be expected between the human neonate and adult. For the organophosphates, the greater sensitivity of postnatal rats, and, by analogy, that expected for human neonates, is correlated with generally lower levels of the enzymes involved in organophosphate deactivation.

Age Factors↗
PubMed1976

Gas chromatographic analysis of heptafluorobutyryl derivatives of some carbamate insecticides.

The gas chromatography (GC) of a number of carbamate insecticides as their heptafluorobutyryl derivatives has been studied. The reaction makes use of heptafluorobutyric anhydride with trimethylamine in benzene as a catalyst. Conversion of the insecticides to their products is complete in 15-20 min at room temperature. The same reaction proved satisfactory for trifluoroacetylation. The excess reagent and trimethylamine are removed by partitioning with water in the reaction test tube. An aliquot of the organic phase is used for analysis. The heptafluorobutyryl derivatives are stable for several days on the lab bench without removal of the aqueous phase from the test tube. GC detection was carried out with a Coulson conductivity detector in the halogen (reductive) mode. About 1.0 ng produced a 50% full-scale response for most of the carbamates (3 min retention time) on 3% OV-1. This method was applied to the analysis of several carbamates spiked in corn, mustard greens, turnip greens, lettuce and cabbage.

Butyrates↗
PubMed1980

Simplified method for the analysis of some carbamate insecticides in foliage, forest soil and fish tissue by direct gas-liquid chromatography.

A simplified and sensitive method for the analysis of eight carbamate insecticide residues in foliage, forest soil and fish tissue by direct gas-liquid chromatography (GLC) is described. After fortification, the carbamate residues were extracted from the natural substrates by homogenization in ethyl acetate. The interfering co-extratives present in the crude extracts were removed by filtration through Whatman GF/A glass microfibre after coagulation. The carbamate residues were re-extracted into dichloromethane and directly analyzed intact by GLC with a Tracor Model 702 nitrogen-phosphorus detector. The rate of recovery for aminocarb, carbofuran, carbaryl, methomyl, mexacarbate, pirimicarb and propoxur was better than 80% at 5.0-ppm and 0.50-ppm levels. Slightly less than 60% was recovered for methiocarb.

Animals↗
PubMed2000

Determination of carbamate residues in fruits and vegetables by matrix solid-phase dispersion and liquid chromatography-mass spectrometry.

Thirteen carbamates were analysed in orange, grape, onion and tomatoes by matrix solid-phase dispersion (MSPD) followed by liquid chromatography-mass spectrometry (LC-MS). Electrospray (ES) and atmospheric pressure chemical ionisation (APCI) were compared and both gave similar results in terms of sensitivity and structural information because at 20 V fragmentor voltages the fragmentation is minimal. The efficiency of different solid-phases (C18, C8, cyano, amine and phenyl) for the MSPD was compared. Mean recoveries using C8 varied from 64 to 106% with relative standard deviations of 5-15% in the concentration range of 0.01-10 mg kg(-1). Matrix constituents did not interfere significantly with the ionisation process of carbamates. The limits of detection were typically in the 0.001-0.01 mg kg(-1) range, which were between 10 and 100 times lower than the maximum residue levels (MRLs) established by the European Union (EU). The method was applied to residue detection in fruit and vegetable samples taken from Valencian markets, in which carbamates were detected at low concentrations.

Carbamates↗
PubMed2000

Automated in-tube solid-phase microextraction-high-performance liquid chromatography for carbamate pesticide analysis.

In-tube solid-phase microextraction (SPME) is an automated version of SPME that can be easily coupled to a conventional HPLC autosampler for on-line sample preparation, separation and quantitation. It has been termed "in-tube" SPME because the extraction phase is coated inside a section of fused-silica tubing rather than coated on the surface of a fused-silica rod as in the conventional syringe-like SPME device. The new in-tube SPME technique has been demonstrated as a very efficient extraction method for the analysis of polar and thermally labile analytes. The in-tube SPME-HPLC method used with the FAMOS autosampler from LC Packings was developed for detecting polar carbamate pesticides in clean water samples. The main parameters relating to the extraction and desorption processes of in-tube SPME (selection of coatings, aspirate/dispense steps, selection of the desorption solvents, and the efficiency of desorption solvent, etc.) were investigated. The method was evaluated according to the reproducibility, linear range and limit of detection. This method is simple, effective, reproducible and sensitive. The relative standard deviation for all the carbamates investigated was between 1.7 and 5.3%. The method showed good linearity between 5 and 10000 microg/l with correlation coefficients between 0.9824 and 0.9995. For the carbamates studied, the limits of detection observed are lower than or similar to that of US Environmental Protection Agency or National Pesticide Survey methods. Detection of carbaryl present in clean water samples at 1 microg/l is possible.

Carbamates↗