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The impairment of mobility and development in freshwater snails (Physa fontinalis and Lymnaea stagnalis) caused by herbicides.

1. The pulmonate freshwater snails Physa and Lymnaea and the earthworms Eisenia and Lumbricus can take up and concentrate a carbamate herbicide (chlorpropham). 2. The mobility of freshwater snails was diminished in the presence of the herbicides chlorpropham (carbamate), cycloate (thiocarbamate), pentanochlor (amide) and chloroxurone (urea derivate). 3. The egg-assemblies of Lymnaea stagnalis turned out to be suitable objects for testing the influences of herbicides upon embryonic development. 4. In the presence of chlorpropham, chloroxurone, cycloate, propanil, simazine and terbutryne, all applied in concentrations lower than in practical use, the period of egg-maturing was delayed and the total number of dead embryos increased. 5. Developing snail eggs were very sensitive towards triazine herbicides (simazine, terbutryne) reflecting in an ED50-value lower than 10(-7) M. 6. Similar herbicidal-induced effects suggested that the developing stages of snail embryos may be suitable models for the ecologically more important but experimentally less accessible earthworms.

Animals↗

Anti-herbicide single-chain antibody expression confers herbicide tolerance in transgenic plants.

An anti-chlorpropham single-chain variable-fragment (scFv) gene was introduced into Arabidopsis in a manner to express the antibody fragment in each of four different subcellular compartments. The accumulation of scFv in transgenic plants was detected by targeting the fragment in the endoplasmic reticulum or apoplastic space, or by expressing the fragment as a glycosylphosphatidylinositol-anchored protein, while no accumulation could be detected by targeting the fragment in the cytosol. Transgenic plants accumulating the scFv gene at a high level in the endoplasmic reticulum had enhanced tolerance to chlorpropham in comparison with the non-transformants.

Antibodies↗

Optimization of microwave-assisted extraction and supercritical fluid extraction of carbamate pesticides in soil by experimental design methodology.

Orthogonal array design (OAD) was applied for the first time to optimize microwave-assisted extraction (MAE) and supercritical fluid extraction (SFE) conditions for the analysis of four carbamates (propoxur, propham, methiocarb, chlorpropham) from soil. The theory and methodology of a new OA16 (4(4)) matrix derived from a OA16 (2(15)) matrix were developed during the MAE optimization. An analysis of variance technique was employed as the data analysis strategy in this study. Determinations of analytes were completed using high-performance liquid chromatography (HPLC) with UV detection. Four carbamates were successfully extracted from soil with recoveries ranging from 85 to 105% with good reproducibility (approximately 4.9% RSD) under the optimum MAE conditions: 30 ml methanol, 80 degrees C extraction temperature, and 6-min microwave heating. An OA8 (2(7)) matrix was employed for the SFE optimization. The average recoveries and RSD of the analytes from spiked soil by SFE were 92 and 5.5%, respectively except for propham (66.3+/-7.9%), under the following conditions: heating for 30 min at 60 degrees C under supercritical CO2 at 300 kg/cm2 modified with 10% (v/v) methanol. The composition of the supercritical fluid was demonstrated to be a crucial factor in the extraction. The addition of a small volume (10%) of methanol to CO2 greatly enhanced the recoveries of carbamates. A comparison of MAE with SFE was also conducted. The results indicated that >85% average recoveries were obtained by both optimized extraction techniques, and slightly higher recoveries of three carbamates (propoxur, propham and methiocarb) were achieved using MAE. SFE showed slightly higher recovery for chlorpropham (93 vs. 87% for MAE). The effects of time-aged soil on the extraction of analytes were examined and the results obtained by both methods were also compared.

Carbamates↗

Influence of clay minerals on the hydrolysis of carbamate pesticides.

Using batch experiments, we investigated the influence of clay minerals (montmorillonite, beidellite, illite, and vermiculite) on the hydrolysis of five carbamate pesticides: carbosulfan, carbofuran, aldicarb, pirimicarb, and chlorpropham. Compared to the other minerals, montmorillonite had the strongest influence on the hydrolysis of these carbamates. Montmorillonite enhanced the hydrolysis of carbosulfan and aldicarb. In contrast, the hydrolysis of chlorpropham was inhibited by montmorillonite, probably because of its strong adsorption on montmorillonite. The hydrolysis of pirimicarb was not affected by montmorillonite. The presence of organic substances, phosphate, and fluoride in suspensions decreased the catalytic activity of montmorillonite. Surface acidity of montmorillonite and/or formation of surface chelates are probably the key factors of surface catalysis in the case of the hydrolysis of carbosulfan.

Adsorption↗

Covalent binding of the benzamide RH-4032 to tubulin in suspension-cultured tobacco cells and its application in a cell-based competitive-binding assay.

The benzamide, RH-4032, was found to be a potent antimicrotubule agent in tobacco (Nicotiana tabacum) cells. It strongly inhibited root growth and produced swollen club-shaped roots, an accumulation of cells in arrested metaphase, and loss of microtubules. RH-4032 inhibited the in vitro assembly of bovine tubulin into microtubules, with inhibition requiring a relatively long incubation period. Treatment of tobacco suspension-cultured cells or isolated bovine tubulin with [(14)C]RH-4032, and analysis of radiolabeled protein revealed a highly specific covalent attachment to beta-tubulin. Binding of [(3)H]RH-4032 in tobacco suspension-cultured cells was shown to be saturable and to be influenced by pre-incubation of the cells with various antimicrotubule agents: Binding of [(3)H]RH-4032 was inhibited by the benzamides, pronamide and zarilamide, the N-phenylcarbamate, chlorpropham, and the microtubule-stabilizing drug, paclitaxel, whereas trifluralin and amiprophosmethyl were not inhibitory. A common characteristic of agents that cause microtubule disassembly was a slight enhancement of [(3)H]RH-4032 binding at low concentrations, which did not occur with the microtubule-stabilizing agent paclitaxel. For structural analogs of RH-4032 and various N-phenylcarbamates, it was shown that the ability to inhibit binding of [(3)H]RH-4032 was correlated with the ability to inhibit tobacco root elongation. The results suggest a common binding site on beta-tubulin for RH-4032, pronamide, zarilamide, and chlorpropham, which is distinct from the binding site(s) for trifluralin and amiprophosmethyl. RH-4032 provides a unique approach to studying effects of antimicrotubule agents on plant cells by allowing competitive tubulin binding assays to be conducted in whole cells.

Amino Acid Chloromethyl Ketones↗

cps1+, a Schizosaccharomyces pombe gene homolog of Saccharomyces cerevisiae FKS genes whose mutation confers hypersensitivity to cyclosporin A and papulacandin B.

The Schizosaccharomyces pombe cps1-12 (for chlorpropham supersensitive) mutant strain was originally isolated as hypersensitive to the spindle poison isopropyl N-3-chlorophenyl carbamate (chlorpropham) (J. Ishiguro and Y. Uhara, Jpn. J. Genet. 67:97-109, 1992). We have found that the cps1-12 mutation also confers (i) hypersensitivity to the immunosuppressant cyclosporin A (CsA), (ii) hypersensitivity to the drug papulacandin B, which specifically inhibits 1,3-beta-D-glucan synthesis both in vivo and in vitro, and (iii) thermosensitive growth at 37 degrees C. Under any of these restrictive treatments, cells swell up and finally lyse. With an osmotic stabilizer, cells do not lyse, but at 37 degrees C they become multiseptated and multibranched. The cps1-12 mutant, grown at a restrictive temperature, showed an increase in sensitivity to lysis by enzymatic cell wall degradation, in in vitro 1,3-beta-D-glucan synthase activity (173% in the absence of GTP in the reaction), and in cell wall biosynthesis (130% of the wild-type amount). Addition of Ca2+ suppresses hypersensitivity to papulacandin B and septation and branching phenotypes. All of these data suggest a relationship between the cps1+ gene and cell wall synthesis. A DNA fragment containing the cps1+ gene was cloned, and sequence analysis indicated that it encodes a predicted membrane protein of 1,729 amino acids with 15 to 16 transmembrane domains. S. pombe cps1p has overall 55% sequence identity with Fks1p or Fks2p, proposed to be catalytic or associated subunits of Saccharomyces cerevisiae 1,3-beta-D-glucan synthase. Thus, the cps1+ product might be a catalytic or an associated copurifying subunit of the fission yeast 1,3-beta-D-glucan synthase that plays an essential role in cell wall synthesis.

Amino Acid Sequence↗

Preparation of N-substituted aryl and alkyl carbamates and their inhibitory effect on oat seed germination.

A series of N-substituted aryl and alkyl carbamates (RNHCOOR'; R: aryl, alkyl; R': aryl, alkyl) was prepared and screened for inhibitory activity toward the germination of oat seeds. The activity of each compound was compared with that of chlorpropham (isopropyl 3-chlorocarbanilate). Some of the synthetic carbamates possessing the N-(phenylthio)methyl group, PhSCH2NHCOOR', showed inhibitory activity close or comparable to that of chlorpropham.

Avena↗

Evidence that herbicides relaxing smooth and oblique-striated muscles affect the muscle cell membrane.

1. From the example of two herbicides [chlorpropham (CIPC) and terbutryn], it has been shown that such compounds inhibit spontaneously occurring, as well as pharmacologically (ACh, KCl, caffeine) or electrically (negative DC) evoked tonic and phasic activities in different smooth and oblique-striated muscles of snails [penis retractor muscle (PRM) of Helix], worms (torsos and muscle segments of Lumbricus and Eisenia) and mice (small intestine of Mus). In PRM preparations, experiments with the denervating drugs 6-OHDA, -5,6-DHT, and reserpine, or with the serotonergic receptor blocker methysergide, produced evidence that the herbicidal side-effect was not caused by action on the nervous system. 3. A relaxant effect on ACh-evoked contractions in the PRM was induced by drugs altering the Ca2+ equilibrium, for example, theophylline, papaverine, chlorpromazine, or trifluoperazine. 4. In addition, an extracellular Ca2+ deficiency or the presence of papaverine led to an enhancement of a CIPC-caused inhibition of ACh- or KCl-induced contractions. 5. The amplitudes of chemically evoked contractions in "skinned muscle cells" of Helix PRM or Lumbricus segments were influenced neither by CIPC nor by terbutryn. 6. CIPC was concentrated by the intact PRM and by a membrane containing PRM fraction, as well as by the worms' circular muscle system. 7. A fluorescent CIPC analogue, dansyl-3-chloroaniline, characterized by a similar inhibiting property on the induced contractions was detected at the border of PRM cells. 8. It is concluded that in the different muscle systems the side-effect of the herbicidal compounds is located in the outer muscle cell membrane where a Ca2+-dependent mechanism may be concerned.

Animals↗

Some applications of solid phase micro extraction (SPME) in the analysis of pesticide residues in food.

The Solid Phase Micro-Extraction (SPME) technique was applied to analyze chlorpropham in potatoes and amitraz in honey. The homogenized sample, suspended in water and stirred, was extracted with a 100 microns thick polidimetylsiloxane fiber and desorbed into the injection port of a gas chromatograph/mass-spectrometer (quadrupole) operating in single ion monitoring. Sensitivities down to 0.01 mg/Kg and linear responses in the range of 0.01-0.1 mg/Kg were obtained. The results of SPME pesticide residue analysis in potatoes corresponded to those obtained with a traditional multiresidue method.

Chlorpropham↗

Genetic toxicity of a mixture of fifteen pesticides commonly found in the Italian diet.

To determine the toxicological effects of complex mixtures of pesticides, we obtained data on 100 pesticide residues in common foods of central Italy. Fifteen pesticides were more regularly detected at higher levels (dithiocarbamates, benomyl/carbendazim, thiabendazole, diphenylamine, chlorthalonil, procymidone, fenarimol, chlorpropham, vinchlozolin, methidathion, chlorpyriphos-ethyl, parathion-methyl, parathion, chlorfenviphos, pirimiphos-ethyl). Using itemized data on daily food consumption in Italy, we calculated that the average exposure for an adult subject was 716 micrograms/day, ranging from 148 micrograms of dithiocarbamates to 1 microgram of pirimiphos-ethyl. We made a mixture of these 15 pesticides at concentrations proportional to the ratio determined in foods and tested it with the Salmonella-microsome assay, with and without metabolic activation with PCB-induced rat liver S9. No mutagenic activity was observed at concentrations up to 500 micrograms/plate. We also tested the same mixture at concentrations ranging from 0.1 to 20 micrograms/ml on human lymphocytes in vitro, and observed a slight but statistically significant increase in sister-chromatid exchanges at 1 microgram/ml. We also administered the mixture in corn oil by gavage to Wistar rats at doses of 1, 10, and 100 micrograms/kg. After 24 hr the ratio between bone marrow polychromatic and normochromatic lymphocytes (a sign of cellular toxicity) was decreased by the exposure, but we did not observe a significant increase in the frequency of micronuclei. We conclude that the pesticide mixture did not have appreciable genotoxic activity in the assays used.

Adult↗

[Herbicide residues in some herbs (author's transl)].

Residue occurrence is discussed with use of 14 herbicides (Alachlor, Chloridazone, Chlorpropham, Chloroxuron, Chlorthal-methyl, Desmetryne, Lenacil, Linuron, Methabenzthiazuron, Monolinuron, Na-propamide, Pendimethalin, Phenmedipham and Terbutryne) on 6 herbs (borage, dill, garden-chervil, garden cress, anise and sorrel) in the light of residue analyses (from field trials over two seasons with analyses carried out in two laboratories). The methods are outlined; limits of the determinations and recoveries are given.

Carbamates↗