The Experts below are selected from a list of 225 Experts worldwide ranked by ideXlab platform
Jou Fang Deng - One of the best experts on this subject based on the ideXlab platform.
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Metobromuron/metolachlor ingestion with late onset methemoglobinemia in a pregnant woman successfully treated with methylene blue
Journal of toxicology. Clinical toxicology, 1995Co-Authors: Chen-chang Yang, Sheau Feng Hwang, Min Min Chou, Jou Fang DengAbstract:Metobromuron, a substituted urea herbicide, is widely used for control of grasses and broad-leaved weeds in Taiwan. Major systemic toxicity has not been reported following poisoning. A 22-year-old woman at 36 weeks of gestation was admitted to the emergency department three hours after ingestion of a mixture of 25% Metobromuron and 25% metolachlor. Though stable initially, she developed central cyanosis 12 hours later. Emergent cesarean section was considered but administration of intravenous methylene blue readily reversed the cyanosis and prevented the operation. Recurrent cyanosis did not develop. Normal vaginal delivery occurred 17 days after the poisoning. Follow-up for four years revealed normal growth of the child. Metobromuron poisoning, like other urea herbicides, may cause methemoglobinemia via its hydrolysis products. Administration of methylene blue is effective treatment and should be considered in the treatment of methemoglobinemia following urea herbicide poisoning.
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Metobromuron metolachlor ingestion with late onset methemoglobinemia in a pregnant woman successfully treated with methylene blue
Clinical Toxicology, 1995Co-Authors: Chen-chang Yang, Sheau Feng Hwang, Min Min Chou, Jou Fang DengAbstract:Metobromuron, a substituted urea herbicide, is widely used for control of grasses and broad-leaved weeds in Taiwan. Major systemic toxicity has not been reported following poisoning. A 22-year-old woman at 36 weeks of gestation was admitted to the emergency department three hours after ingestion of a mixture of 25% Metobromuron and 25% metolachlor. Though stable initially, she developed central cyanosis 12 hours later. Emergent cesarean section was considered but administration of intravenous methylene blue readily reversed the cyanosis and prevented the operation. Recurrent cyanosis did not develop. Normal vaginal delivery occurred 17 days after the poisoning. Follow-up for four years revealed normal growth of the child. Metobromuron poisoning, like other urea herbicides, may cause methemoglobinemia via its hydrolysis products. Administration of methylene blue is effective treatment and should be considered in the treatment of methemoglobinemia following urea herbicide poisoning.
Julio Menéndez - One of the best experts on this subject based on the ideXlab platform.
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Resistance to Substituted Urea Herbicides inLolium rigidumBiotypes
Pesticide Biochemistry and Physiology, 1997Co-Authors: Rafael De Prado, Jose L. De Prado, Julio MenéndezAbstract:Abstract Two populations of Lolium rigidum (R 1 and R 2 ) from a monoculture of winter wheat were treated with diclofop-methyl, whereas another population of L. rigidum (R 3 ) was treated with diclofop-methyl plus chlorotoluron or diclofop-methyl plus isoproturon. The R 1 biotype is resistant to chlorotoluron and isoproturon (ED 50 R 1 /ED 50 S values of 6.5 and 4.2, respectively), while the R 3 also exhibits resistance to chlorotoluron and isoproturon (ED 50 R 3 /ED 50 S values of 9.26 and 5.53, respectively). The diclofop-methyl-resistant R 2 biotype was similarly sensitive to both substituted ureas, as was the susceptible (S) biotype. The resistance mechanism in the R 1 and R 3 biotypes is not due to reduced target site affinity for herbicides. There was no difference in the absorption and translocation of [ 14 C]chlorotoluron in the resistant and susceptible biotypes. Fast fluorescence induction curves showed that substituted ureas inhibited whole-leaf photosynthesis in all biotypes. The R 1 and R 3 biotypes later recovered fluorescence activity at a slightly slower rate in the R 1 biotype than in the R 3 biotype. The R 3 population was also tolerant to benzthiazuron, buturon, fenuron, methabenzthiazuron, Metobromuron, metoxuron, and monolinuron, with tolerance at a lower level to chloroxuron, diuron, and linuron. This biotype was susceptible to chlorobromuron. The R 1 biotype was tolerant to benzthiazuron and metoxuron and was less tolerant to buturon, fenuron, methabenzthiazuron, and Metobromuron, while this biotype was susceptible to chlorobromuron, chloroxuron, diuron, linuron, and monolinuron. L. rigidum biotypes produced the same pattern of metabolites, but the R 1 and R 3 resistant biotypes detoxified the chlorotoluron to conjugated chlorotoluron at a higher rate than the R 2 and S susceptible biotypes. In all biotypes treated with 1-aminobenzotriazole, a cytochrome P450 inhibitor, N-dealkylation was not affected, while ring methyl hydroxylation was strongly inhibited. These data suggested that the resistance mechanism in both biotypes is due to chlorotoluron metabolism via alkyl oxidation, and this is greater in R 3 than R 1 . The cytochrome P450 enzyme could be involved in this oxidation reaction.
Claire Richard - One of the best experts on this subject based on the ideXlab platform.
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phototransformation of Metobromuron in the presence of tio2
Applied Catalysis B-environmental, 2005Co-Authors: Amina Aminekhodja, Abdelaziz Boulkamh, Claire RichardAbstract:The photocatalytic degradation of the herbicide Metobromuron was studied, using TiO2 photocatalysts (Degussa P25 and Millennium PC50, PC100, PC105 and PC500). Intermediate products were identified by means of liquid chromatography–mass spectrometry (LC–MS–MS) using electrospray (ES) interfacing technique. In order of importance, the main reaction pathways were demethoxylation of the urea chain, ring oxidation leading to ortho hydroxylation with respect to the N atom, substitution of Br by OH, ring oxidation with formation of the meta hydroxylated compound. Demethylation of the demethoxylated product occurred as a secondary reaction. Formation of bromide ions was observed too. In the presence of 2-propanol used as a hydroxyl radical scavenger, demethoxylation was drastically inhibited while the other reactions were only partly inhibited. It suggests that demethoxylation was exclusively due to the oxidation by hydroxyl radicals, whereas the other reactions involved positive holes too. The degradation rate of Metobromuron varied in the order: PC50 < PC100 < PC105 < PC500 < Degussa P25. TiO2 Degussa P25 was therefore the most efficient photocatalyst although its surface area was lower than that of most of Millennium TiO2.
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Phototransformation of Metobromuron in the presence of TiO2
Applied Catalysis B-environmental, 2005Co-Authors: Amina Amine-khodja, Abdelaziz Boulkamh, Claire RichardAbstract:The photocatalytic degradation of the herbicide Metobromuron was studied, using TiO2 photocatalysts (Degussa P25 and Millennium PC50, PC100, PC105 and PC500). Intermediate products were identified by means of liquid chromatography–mass spectrometry (LC–MS–MS) using electrospray (ES) interfacing technique. In order of importance, the main reaction pathways were demethoxylation of the urea chain, ring oxidation leading to ortho hydroxylation with respect to the N atom, substitution of Br by OH, ring oxidation with formation of the meta hydroxylated compound. Demethylation of the demethoxylated product occurred as a secondary reaction. Formation of bromide ions was observed too. In the presence of 2-propanol used as a hydroxyl radical scavenger, demethoxylation was drastically inhibited while the other reactions were only partly inhibited. It suggests that demethoxylation was exclusively due to the oxidation by hydroxyl radicals, whereas the other reactions involved positive holes too. The degradation rate of Metobromuron varied in the order: PC50
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Photochemical transformation of aqueous para-halogenophenylureas: evidence for the intermediary formation of carbenes
New Journal of Chemistry, 2000Co-Authors: Abdelaziz Boukhram, Claire RichardAbstract:N-Substituted 4-iminocyclohexa-2,5-dienylidenes (λmax = 300 and 405 nm) are detected at pulse end upon laser flash photolysis of aqueous monuron and Metobromuron. In oxygenated medium these carbenes are converted into N-substituted iminoquinone-O-oxides (λmax = 300 nm and 460 nm) and in the presence of H-donor molecules into N-substituted anilino radicals (λmax = 430 nm).
Susan A. Bourne - One of the best experts on this subject based on the ideXlab platform.
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Investigation of the inclusion of the herbicide Metobromuron in native cyclodextrins by powder X-ray diffraction and isothermal titration calorimetry.
Carbohydrate research, 2009Co-Authors: Vincent J. Smith, Natalia M. Rougier, Rita H. De Rossi, Mino R. Caira, Elba I. Buján, Mariana A. Fernández, Susan A. BourneAbstract:We report the formation of inclusion complexes between the phenylurea herbicide Metobromuron [3-(p-bromophenyl)-1-methoxy-1-methylurea] and β- and γ-cyclodextrin in the solid state. Formation of crystalline inclusion complexes by the kneading method was confirmed by powder X-ray diffraction and further structural characterization using the principles of isostructurality followed. In addition, ΔH°, ΔS°, ΔG° and the association constants (K) at 298 K were determined for complex formation in solution using isothermal titration calorimetry. The magnitudes of K for the formation of 1:1 complexes between Metobromuron and α-, β- and γ-CD were estimated as 598, 310 and 114, respectively.
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Cyclodextrin inclusion of four phenylurea herbicides: determination of complex stoichiometries and stability constants using solution 1H NMR spectroscopy
Supramolecular Chemistry, 2009Co-Authors: Vincent J. Smith, Mino R. Caira, Susan A. Bourne, Diana Bogdan, Mircea Bogdan, Sorin I. FărcaşAbstract:An inclusion complex formation between α- and β-cyclodextrin and four phenylurea analogues, namely Metobromuron, monolinuron, monuron and fenuron, is reported. Complex formation was established using solution 1H NMR spectroscopy. Complex stoichiometries were determined by the method of continuous variation using the chemically induced shifts of both the host and guest protons. An analysis of the spectroscopic data revealed the stoichiometry as 1:1 in all cases while a further analysis of the same data yielded values for the association constant K ranging from 208 to 2749 M− 1. From the observed chemical shifts it was deduced that in all cases, only the guest aromatic ring enters the host cavities, the substituted urea moiety protruding from the secondary rim in the case of α-cyclodextrin, but from the primary rim in the case of β-cyclodextrin.
Vincent J. Smith - One of the best experts on this subject based on the ideXlab platform.
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Investigation of the inclusion of the herbicide Metobromuron in native cyclodextrins by powder X-ray diffraction and isothermal titration calorimetry.
Carbohydrate research, 2009Co-Authors: Vincent J. Smith, Natalia M. Rougier, Rita H. De Rossi, Mino R. Caira, Elba I. Buján, Mariana A. Fernández, Susan A. BourneAbstract:We report the formation of inclusion complexes between the phenylurea herbicide Metobromuron [3-(p-bromophenyl)-1-methoxy-1-methylurea] and β- and γ-cyclodextrin in the solid state. Formation of crystalline inclusion complexes by the kneading method was confirmed by powder X-ray diffraction and further structural characterization using the principles of isostructurality followed. In addition, ΔH°, ΔS°, ΔG° and the association constants (K) at 298 K were determined for complex formation in solution using isothermal titration calorimetry. The magnitudes of K for the formation of 1:1 complexes between Metobromuron and α-, β- and γ-CD were estimated as 598, 310 and 114, respectively.
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Cyclodextrin inclusion of four phenylurea herbicides: determination of complex stoichiometries and stability constants using solution 1H NMR spectroscopy
Supramolecular Chemistry, 2009Co-Authors: Vincent J. Smith, Mino R. Caira, Susan A. Bourne, Diana Bogdan, Mircea Bogdan, Sorin I. FărcaşAbstract:An inclusion complex formation between α- and β-cyclodextrin and four phenylurea analogues, namely Metobromuron, monolinuron, monuron and fenuron, is reported. Complex formation was established using solution 1H NMR spectroscopy. Complex stoichiometries were determined by the method of continuous variation using the chemically induced shifts of both the host and guest protons. An analysis of the spectroscopic data revealed the stoichiometry as 1:1 in all cases while a further analysis of the same data yielded values for the association constant K ranging from 208 to 2749 M− 1. From the observed chemical shifts it was deduced that in all cases, only the guest aromatic ring enters the host cavities, the substituted urea moiety protruding from the secondary rim in the case of α-cyclodextrin, but from the primary rim in the case of β-cyclodextrin.