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PubMed2005

Comparison of in vitro and in vivo ectoparasiticide activity of experimental benzimidazole-carbamate with permethrin and amitraz.

A series of in vitro and in vivo bioassays were conducted to assess the ectoparasiticide activity of isopropyl-4-nitro-2,6-bis(trifluoromethyl)-1-benzimidazole-carbamate, an experimental benzimidazole-carbamate class compound. This compound was less potent than permethrin against ectoparasiticide-susceptible larvae of the lone star tick, Amblyomma americanum (L.) (Acari: Ixodidae); larvae of the southern cattle tick, Boophilus microplus (Canestrini); and adult stable fly, Stomoxys calcitrans (L.) (Diptera: Muscidae) in vitro, but it was significantly more potent than permethrin against the Santa Luiza strain of B. microplus known to possess high-level resistance to amitraz and pyrethroids. In contrast, the benzimidazole-carbamate was substantially more efficacious than permethrin when applied topically onto rats that were infested with A. americanum nymphs. These results suggest that this experimental compound may be a viable candidate ectoparasiticide that retains significant activity against resistant B. microplus and also suggests that the benzimidazole-carbamate chemistry may be useful for addressing the growing problem of resistance in ectoparasites.

Animals↗
PubMed1999

Carbamate and organophosphate poisoning in young children.

OBJECTIVE: Retrospective evaluation of the clinical course of carbamate and organophosphate poisoning in young children. DESIGN: The records of 36 children intoxicated with carbamate and 16 children intoxicated with organophosphate (age range: 2 to 8 years, median: 2.8 years) were examined retrospectively. The carbamate agents were identified as methomyl or aldicarb, and the organophosphate as parathion, fenthion, malathion, and diazinon. The causes of poisoning were accidental ingestion in 46 children and inhalation in six children. CLINICAL SETTING: Pediatric Intensive Care Unit of a teaching hospital. INTERVENTIONS: Gastric lavage was performed, and activated charcoal was administered to all children who had ingested poisonous pesticides. Atropine sulphate was administered intravenously in repeated doses to all children with bradycardia, diarrhea, salivation, and miosis. Obidoxime chloride was administered to patients with organophosphate poisoning and to those in whom the ingested material was unidentified on admission. RESULTS: Predominant symptoms were related to central nervous system depression and severe hypotonia. Other clinical signs such as miosis, diarrhea, salivation, bradycardia, and fasciculation were less frequent, while tearing and diaphoresis were not observed. Pulmonary edema developed in six patients with organophosphte poisoning. Three children required mechanical ventilation for several hours. One child (organophosphate poisoning) died shortly after arrival at the emergency department. All other children recovered completely. CONCLUSION: Based on a relatively large group of young pediatric patients with carbamate and organophosphate poisoning, it is concluded that the clinical presentation differed from those described in adults. Absence of classic muscarinic effects does not exclude the possibility of cholinesterase inhibitor agents poisoning in young children with central nervous system depression.

Adult↗
PubMed1987

Studies on the enzymatic hydrolysis of amino acid carbamates.

Several commercially available enzymes were tested for their ability to hydrolyze amino acid carbamates. No activity was found with pig liver esterase, the hydantoinase from Pseudomonas fluorescens DSM 84, or the urease from jack beans. A stereoselective cleavage of the carbamyl group yielding L-amino acids was observed by acylase and acetylcholinesterases from bovine and human erythrocytes. Racemic mixtures of N-(methoxycarbonyl)-DL-alanine, N-(ethoxycarbonyl)-DL-alanine, and the corresponding valine carbamates are hydrolyzed to L-alanine and L-valine, respectively, by acylases leaving the D-amino acid carbamates unchanged. The lysine carbamates were not hydrolyzed by acylases. In contrast only the methoxycarbonyl amino acids were split by acetylcholinesterases, which, however, also cleave alpha, epsilon-(N-methoxycarbonyl)-DL-lysine stereoselectively at the alpha position, yielding epsilon-N-methoxycarbonyl-L-lysine. The optimum pH for enzymatic activity of hog kidney acylase was 7.5 and a Km value of 8.2 mM for N-(methoxycarbonyl)-DL-alanine was determined. For the acetylcholinesterases the reaction rate reaches an optimum between pH 7.5 and 8. The Km value was 68 mM for N-(methoxycarbonyl)-DL-alanine.

Acetylcholinesterase↗
PubMed1974

Effect of ether anaesthesia on pharmacokinetics of N-(2 hydroxy ethyl)2-phenyl ethyl carbamate: inhibition of its enterohepatic circulation.

1 The effect of the ether anaesthesia on the plasma half-life of N-(2 hydroxy ethyl) 2-phenyl ethyl carbamate has been studied in rats.2 The plasma half-life of the carbamate was considerably shorter in animals anaesthetized with ether prior to drug administration than in control rats.3 The longer plasma half-life of the carbamate in control animals was shown to be due to enterohepatic circulation.4 Inhibition of this phenomenon by ether was responsible for the shorter plasma half-life of the carbamate in animals anaesthetized with this agent before drug administration.5 The possible mechanisms by which the ether-induced effect is brought about are discussed.

Ampicillin↗
PubMed1979

Rapid absorption from the urinary bladder of a series of n-alkyl carbamates: a route for the recirculation of drugs.

1 The rate of loss of a series of n-alkyl carbamates from the lumen of the urinary bladders of female rats has been studied. 2 The rate of loss obeys first order kinetics and was not affected by water flux across the bladder wall nor by binding of the carbamates to it. 3 The rate of loss of octyl carbamate was reduced by about 76% by the presence of 5% Tween 80. Histological evidence indicates that this may be due to the formation of a thin luminal lining which may be adsorbed Tween 80 or mucopolysaccharide material. 4 The absorption rate of the carbamates was limited by their hydrophilicity but reached a plateau for the more lipophilic homologues with a half life for loss of approximately 10 min. 5 The implications of these results with regard to the recirculation of unmetabolized drugs and hydrolysed conjugates of drugs, the systemic absorption of intravesically applied cancer chemotherapeutic agents and bladder wall permeability to carcinogens are discussed.

Absorption↗
PubMed1991

Orally active carbamate prodrugs of the selective dopamine agonist N-0437: in-vivo activities in the 6-OHDA turning model and in-vitro activities.

The in-vivo activities of eight carbamate prodrugs of the D2-agonist N-0437 were determined by examining the effects of the prodrugs, after their oral administration in rats with unilateral 6-OHDA lesions of the striatum. The resulting contralateral turning was used as an index of the activity of the compounds. A comparison of the area under the curve of the time-effect curves of the prodrugs, revealed a significantly improved duration of action compared with N-0437 during the period 11-15 h after administration, for the propylcarbamate and the dimethoxyphenylcarbamate derivatives. The 2,4-dimethylphenylcarbamate showed a significantly enhanced turning behaviour over the whole 15 h time interval in comparison with N-0437. Three of the nine carbamates were virtually unhydrolysed in rat serum at 37 degrees C, while the other test compounds were hydrolysed relatively slowly, with t1/2 values ranging from 1.5-6 h. The test compounds differed greatly in partition coefficients, which were estimated by RP-HPLC (1-12 times more lipophilic than N-0437). The potential cholinesterase inhibiting properties of the carbamate prodrugs were assessed by a simple in-vitro incubation assay, which showed that only two carbamates were very weak cholinesterase inhibitors.

Administration, Oral↗
PubMedDate not supplied

Long-term neurobehavioral effects of mild poisonings with organophosphate and n-methyl carbamate pesticides among banana workers.

Organophosphate poisoning has been associated with chronic neurobehavioral dysfunction, but no epidemiologic data exist with regard to long-term consequences from carbamate poisoning. This cross-sectional study evaluated the neurobehavioral performances of 81 banana workers who, on average 27 months earlier, had received medical attention not requiring hospitalization for mild occupational poisoning by either an organophosphate or a carbamate pesticide. These performances were compared with those of 130 banana workers who had never sought medical attention for pesticide poisoning. Poisoned subjects did less well than controls on tests measuring psychomotor and visuomotor skills, language function, and affect, the differences being significant for coding skills on the Digit-Symbol test and two tests of neuropsychiatric symptoms. These deficits, in particular a marked increase of neuropsychiatric symptoms, occurred among the organophosphate-poisoned subjects, but small deficits in performance were also seen in the carbamate-poisoned subjects. The performances of the previously poisoned subjects who had had contact with cholinesterase inhibitors within three months before testing were particularly poor. These findings in workers with mild poisoning are consistent with previous findings of persistent damage to the central nervous system from organophosphate poisoning. The possibility of persistent neurobehavioral effects associated with poisonings by nmethyl carbamate insecticides cannot be excluded. Workers with histories of poisoning may be more susceptible to neurobehavioral effects with subsequent exposures.

Adult↗
PubMed2006

Dose-additive inhibition of chinook salmon acetylcholinesterase activity by mixtures of organophosphate and carbamate insecticides.

Organophosphate and carbamate insecticides are widely detected in surface waters of the western United States. These chemicals interfere with acetylcholine-mediated synaptic transmission in the nervous systems of fish and other aquatic animals via the inhibition of AChE (acetylcholinesterase) enzyme activity. Anticholinesterase insecticides commonly co-occur in the environment. This raises the possibility of antagonistic, additive, or synergistic neurotoxicity in exposed fish, including threatened and endangered species of Pacific salmon. We extracted AChE from the olfactory nervous system of chinook salmon (Oncorhynchus tshawytscha) and investigated the inhibitory effects of organophosphates (the oxon derivatives of diazinon, chlorpyrifos, and malathion) and carbamates (carbaryl and carbofuran), alone and in two-way combinations. We found that the joint toxicity of anticholinesterase mixtures can be accurately predicted from the inhibitory potencies of individual chemicals within a mixture. This indicates that organophosphate and carbamate insecticides are noninteractive in terms of AChE inhibition and that it might be possible to estimate the cumulative neurotoxicity of mixtures by simple dose addition. Because organophosphates and carbamates are likely to have additive effects on the neurobehavior of salmon under natural exposure conditions, ecological risk assessments that focus on individual anticholinesterases might underestimate the actual risk to salmon in watersheds in which mixtures of these chemicals occur.

Acetylcholinesterase↗
PubMedDate not supplied

The role of kaolin particles in the performance of a carbamate-based biocide for water bacterial control.

The influence of kaolin particles on the activity of Pseudomonas fluorescens and on the efficacy of a carbamate-based biocide was investigated. The results indicated that kaolin particles stimulated the activity of the bacteria for all buffered pH values studied (5, 7, and 9); this effect being more evident for the tests carried out at pH 5 and 9. The presence of the clay in P. fluorescens suspensions decreased the efficiency of disinfection of the carbamate. The results also showed that kaolin was very effective in removing carbamate from the culture media. Therefore, the biocide concentration in the solution decreased, and consequently its availability to the bacteria was reduced. The results could be explained by the interaction between kaolin particles and carbamate and by the changes in the configuration of kaolin aggregates, depending on the pH value.

Adsorption↗
PubMed1991

Anticholinesterase activity of potential therapeutic 5-(1,3,3-trimethylindolinyl) carbamates.

Six N-alkyl and N-aryl 5-(1,3,3-trimethylindolinyl) carbamates were synthesized and studied for their structure-activity relationships in inhibiting eel acetylcholinesterase (AChE). The carbamates were 5-(1,3,3-trimethylindolinyl)N,N-dimethylcarbamate (Cui Xing Ning) (I), 5-(1,3,3-trimethylindolinyl)N,N-diethylcarbamate (IV), 5-(1,3,3-trimethylindolinyl)N-ethylcarbamate (III), 5-(1,3,3-trimethylindolinyl)N,N-diethylcarbamate (IV), 5-(1,3,3-trimethylindolinyl)N-heptylcarbamate (V), and 5-(1,3,3-trimethylindolinyl)N-(3-chlorophenyl)carbamate (VI). The inhibition studies were carried out at 25.0 degrees C at pH 7.60. The rank order of the ki values for eel AChE inhibition is II > V > I > III > VI > IV. Compound II has a greater affinity for the enzyme than any irreversible inhibitor cited in the literature (Kd = 7.14 x 10(-8) M). Our findings should aid in the application of these carbamates (1) for counteracting the cholinergic problems associated with various diseases, and (2) for developing potential pretreatment compounds for organophosphate poisoning.

Acetylcholinesterase↗
PubMed1995

Poisoning due to illegal use of carbamates as a rodenticide in Rio de Janeiro.

Carbamate insecticides (mainly aldicarb) are illegally commercialized as rat poisons and commonly used by the population of Rio de Janeiro for this purpose. A retrospective study concerning 189 cases (80 men, 109 women) of carbamate poisoning referred to the Poison Control Center of Rio de Janeiro throughout 1993 is described. The causes of carbamate poisoning were suicide attempts (65%) and accidental ingestions (35%). The main signs and symptoms found (86%) were those related to the SLUDGE syndrome (increased salivation, lacrimation, urinary incontinence, diarrhea, gastrointestinal cramping and emesis) which were more commonly seen in adults than in children. Despite treatment with atropine, the case-fatality was 4%. It is concluded that there is a widespread risk of carbamate poisoning in Rio de Janeiro due to its clandestine use as a rodenticide. Effective measures by the government authorities should be implemented to stamp out the illicit commercialization of these compounds.

Adolescent↗
PubMed1996

Clinical and sociodemographic features of acute carbamate and organophosphate poisoning: a study of 70 adult patients in north Jordan.

OBJECTIVE: To define the sociodemographic and clinical aspects of organic phosphate and carbamate poisoning. DESIGN: The records of 70 adults (33 males and 37 females) with carbamate or organophosphate intoxication admitted to a North Jordan Teaching Hospital over a five-year period were reviewed retrospectively. These patients represented 10% of all drug overdoses admitted over the same period. RESULTS: The most cases occurred in the 15-19 year-old age group and the female to male ratio was 1.1:1. Carbamate intoxication was more than twice as common as organophosphate intoxication. Two thirds (64%) of the patients intended to commit suicide, 26% were due to accidental ingestion and the remaining 10% were from occupational exposure. Muscarinic manifestations were the predominant clinical feature followed by central nervous system and then nicotinic manifestations. Low grade fever, not related to infection, was observed in 49% of the patients and respiratory difficulty in 47%, of which 11% required assisted ventilation. Twenty-nine percent of the patients presented with coma. Three patients died for a hospital mortality of 4%. CONCLUSIONS: The widespread use of carbamates and organophosphates as household pesticides and the lack of adequate regulations controlling their sale and application has encouraged teenagers to prefer them as a modality of attempted suicide. This source of poisoning has become a major health problem in some developing countries.

Accidents↗
PubMed1998

[Simultaneous determinations of carbamate pesticides in cereal by high performance liquid chromatography with post-column fluorescence derivatization].

A liquid chromatographic method for the simultaneous determination of carbamate pesticides in cereal by Waters Carbamate Analysis System with post-column fluorescence derivatization is described. The cereal sample homogenate was extracted with acetone and water. The extract was partitioned between 5% sodium chloride solution and dichloromethane. The dichloromethane layer was concentrated to dryness. The residue was dissolved in n-hexane and extracted with acetonitrile (saturated with n-hexane). The acetonitrile layer was decreased with n-hexane (saturated with acetonitrile), then the acetonitrile layer was concentrated to dryness. The residue was dissolved in methanol. It's the test solution for HPLC. Nine carbamate pesticides and their three metabolites were separated by Waters Carbamate Column with gradient elution. Two steps underwent in the post-column system: hydrolysis by NaOH solution and the reaction of the product with o-phthalaldehyde and 2-mercaptoethanol. The resulting fluorescence derivative was detected at 445 nm (excitation at 339 nm). The selectivity, reproducibility and sensitivity of proposed method are better than those reported with other methods. The detection limits was 5 micrograms/kg of samples.

Carbamates↗
PubMed2002

Inhibition of endocytotic functions in Dictyostelium discoideum treated with a carbamate pesticide.

Administration of a carbamate pesticide carbaryl (1-Naphthyl-N-methyl carbamate) at a concentration of 60 and 100 ppm greatly inhibits the endocytotic functions during growth of the cellular slime mold D. discoideum. The ingestion of fluorescien isothiocynate (FITC) labeled E. coli is reduced between 30 and 40% in the treated cells as compared to controls. Similarly, the uptake of FITC-labeled dextran, which has been used as fluid-phase marker for pinocytosis also show 40-50% inhibition in the treated cells. 3H-leucine uptake and incorporation are also inhibited in the treated cells. SDS-PAGE analysis of cytoskeletal proteins shows a higher actin association with the membrane of treated cells. The results demonstrate the detrimental effects of Carbamate on the soil microbe even at a very low concentration and the efficacy of the slime mold cells as a biosensor for the carbamate-induced cytotoxicity.

Actins↗
PubMedDate not supplied

Determination of carbamate insecticides in Chinese medicinal herbs by gas chromatography with a nitrogen-phosphorus detector.

A simplified method for determining carbamate insecticides (including metolcarb, isoprocarb, fenobucarb, carbofuran, pirimicarb, and carbaryl) in Chinese medicinal herbs (White Peony Alba, Red Peony Root, and Baical Skullcap Root) is described. Standards were fortified into Chinese medicinal herbs at 3 levels (0.05-0.5 mg/kg). The carbamates were extracted with dichloromethane in a Soxhlet apparatus and analyzed by gas chromatography with a nitrogen-phosphorus detector. The results showed average recoveries between 80.77 and 104.56%. The method evidenced good robustness, accuracy, and precision for monitoring carbamates in Chinese medicinal herb samples, and it is a suitable alternative to replace the currently dedicated analytical systems. The minimum detectable amount ranged from 3.0 x 10(-10) to 5.0 x 10(-10)g, and the limit of quantification was 0.05 mg/kg. The method is rapid, simple, sensitive, and reproducible, and it can be conveniently used as a low-cost, rapid method for measuring the carbamate insecticide contamination of Chinese medicinal herbs.

Carbamates↗
PubMedDate not supplied

Liquid chromatographic determination of N-methyl carbamate pesticide residues at low parts-per-billion levels in eggs.

A reversed-phase liquid chromatographic (LC) method is presented for the analysis of N-methyl carbamate pesticide residues and piperonyl butoxide in eggs at levels as low as 2 microg/kg (ppb). The study was undertaken to provide data for dietary exposure estimates used in risk analysis. The method uses an acetonitrile extraction followed by liquid-liquid partitioning and normal-phase aminopropyl solid-phase extraction column cleanup. Determination of residues is by reversed-phase LC with an inline postcolumn reaction followed by fluorescence detection. The average recoveries of 21 fortified (most at 2.0 and 20.0 ppb) N-methyl carbamate pesticide residues and the carbamate metabolite 1-naphthol from eggs ranged from 70 to 107%. Recoveries of the pesticide synergist piperonyl butoxide ranged from 63 to 106%. Single-comb White Leghorn hens were treated with the carbamate carbaryl, and the eggs subsequently produced were analyzed for carbaryl and 1-naphthol residues.

Animals↗
PubMed1990

Neuroactive carbamate adducts of beta-N-methylamino-L-alanine and ethylenediamine. Detection and quantitation under physiological conditions by 13C NMR.

beta-N-Methylamino-L-alanine (BMAA) reacts with dissolved carbon dioxide to form two carbamate compounds at physiological pH, temperature and bicarbonate concentration. The reversible reactions of BMAA with dissolved carbon dioxide were monitored by 13C NMR. At 37 degrees C and pH 7.4, the fraction of BMAA existing as the alpha-N-carboxy adduct is 0.22 while the fraction of BMAA existing as the beta-N-carboxy adduct is 0.09. Although both adducts could be implicated in the bicarbonate-dependent neurotoxicity of BMAA (Weiss, J. H., and Choi, D. W. (1988) Science 241, 973-975; Mroz, E. A., Weiss, J. W., and Choi, D. W. (1989) Science 243, 1613), the beta-N-carboxy adduct shares structural characteristics with the appropriate endogenous ligand, glutamic acid. Analogously, the GABA-mimetic properties of ethylenediamine have been attributed to a carbamate adduct, ethylenediamine monocarbamate (Kerr, D. I. B., and Ong, J. (1987) Br. J. Pharmacol. 90, 763-769). Using the same method, we were able to detect directly and quantify the formation of this carbamate under physiological conditions. Information on the carbamate equilibria of these compounds is essential in order to address questions of their neuroactive potency.

Amino Acids, Diamino↗
PubMed1985

Site-specific mutagenesis of ribulose-1,5-bisphosphate carboxylase/oxygenase. Evidence that carbamate formation at Lys 191 is required for catalytic activity.

Site-specific mutagenesis of a cloned gene for ribulose-1,5-bisphosphate carboxylase/oxygenase from Rhodospirillum rubrum was used to examine the functional significance of carbamate activation. Lysine 191, the residue involved in carbamate formation, was replaced with a glutamate in order to mimic the anionic nature of the carbamate. The resulting enzyme was capable of binding the six-carbon transition state analog carboxyarabinitol bisphosphate, but completely lacked catalytic activity. In contrast to the wild-type enzyme, carboxyarabinitol bisphosphate binding was not stabilized by divalent metal and CO2. These observations are consistent with a proposed role for the carbamate in binding the metal required for catalysis.

Amino Acid Sequence↗