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Marshall J Clark - One of the best experts on this subject based on the ideXlab platform.

  • identification and characterization of an esterase involved in Malathion resistance in the head louse pediculus humanus capitis
    Pesticide Biochemistry and Physiology, 2014
    Co-Authors: Deok Ho Kwon, Kyong Sup Yoon, Marshall J Clark
    Abstract:

    Abstract Enhanced Malathion carboxylesterase (MCE) activity was previously reported to be involved in Malathion resistance in the head louse Pediculus humanus capitis (Gao et al., 2006 [8]). To identify MCE, the transcriptional profiles of all five esterases that had been annotated to be catalytically active were determined and compared between the Malathion-resistant (BR-HL) and Malathion-susceptible (KR-HL) strains of head lice. An esterase gene, designated HLCbE3, exhibited approximately 5.4-fold higher transcription levels, whereas remaining four esterases did not exhibit a significant increase in their transcription in BR-HL, indicating that HLCbE3 may be the putative MCE. Comparison of the entire cDNA sequences of HLCbE3 revealed no sequence differences between the BR-HL and KR-HL strains and suggested that no single nucleotide polymorphism is associated with enhanced MCE activity. Two copies of the HLCbE3 gene were observed in BR-HL, implying that the over-transcription of HLCbE3 is due to the combination of a gene duplication and up-regulated transcription. Knockdown of HLCbE3 expression by RNA interference in the BR-HL strain led to increases in Malathion susceptibility, confirming the identity of HLCbE3 as a MCE responsible for Malathion resistance in the head louse. Phylogenetic analysis suggested that HLCbE3 is a typical dietary esterase and belongs to a clade containing various MCEs involved in Malathion resistance.

  • identification and characterization of an esterase involved in Malathion resistance in the head louse pediculus humanus capitis
    Pesticide Biochemistry and Physiology, 2014
    Co-Authors: Deok Ho Kwon, Kyong Sup Yoon, Marshall J Clark
    Abstract:

    Abstract Enhanced Malathion carboxylesterase (MCE) activity was previously reported to be involved in Malathion resistance in the head louse Pediculus humanus capitis (Gao et al., 2006 [8]). To identify MCE, the transcriptional profiles of all five esterases that had been annotated to be catalytically active were determined and compared between the Malathion-resistant (BR-HL) and Malathion-susceptible (KR-HL) strains of head lice. An esterase gene, designated HLCbE3, exhibited approximately 5.4-fold higher transcription levels, whereas remaining four esterases did not exhibit a significant increase in their transcription in BR-HL, indicating that HLCbE3 may be the putative MCE. Comparison of the entire cDNA sequences of HLCbE3 revealed no sequence differences between the BR-HL and KR-HL strains and suggested that no single nucleotide polymorphism is associated with enhanced MCE activity. Two copies of the HLCbE3 gene were observed in BR-HL, implying that the over-transcription of HLCbE3 is due to the combination of a gene duplication and up-regulated transcription. Knockdown of HLCbE3 expression by RNA interference in the BR-HL strain led to increases in Malathion susceptibility, confirming the identity of HLCbE3 as a MCE responsible for Malathion resistance in the head louse. Phylogenetic analysis suggested that HLCbE3 is a typical dietary esterase and belongs to a clade containing various MCEs involved in Malathion resistance.

  • esterase mediated Malathion resistance in the human head louse pediculus capitis anoplura pediculidae
    Pesticide Biochemistry and Physiology, 2006
    Co-Authors: Kyong Sup Yoon, G C Coles, Richard K. Frisbie, Marshall J Clark
    Abstract:

    Resistance in a dual Malathion- and permethrin-resistant head louse strain (BR-HL) was studied. BR-HL was 3.6- and 3.7-fold more resistant to Malathion and permethrin, respectively, compared to insecticide-susceptible EC-HL. S,S,S-Tributylphosphorotrithioate synergized Malathion toxicity by 2.1-fold but not permethrin toxicity in BR-HL. Piperonyl butoxide did not synergize Malathion or permethrin toxicity. Malathion carboxylesterase (MCE) activity was 13.3-fold and general esterase activity was 3.9-fold higher in BRHL versus EC-HL. There were no significant differences in phosphotriesterase, glutathione S-transferase, and acetylcholinesterase activities between strains. There was no differential sensitivity in acetylcholinesterase inhibition by malaoxon. Esterases from BR-HL had higher affinities and hydrolysis efficiencies versus EC-HL using various naphthyl-substituted esters. Protein content of BR-HL females and males was 1.6- and 1.3-fold higher, respectively, versus EC-HL adults. Electrophoresis revealed two esterases with increased intensity and a unique esterase associated with BR-HL. Thus, increased MCE activity and over-expressed esterases appear to be involved in Malathion resistance in the head louse.

  • esterase mediated Malathion resistance in the human head louse pediculus capitis anoplura pediculidae
    Pesticide Biochemistry and Physiology, 2006
    Co-Authors: Kyong Sup Yoon, G C Coles, Richard K. Frisbie, Marshall J Clark
    Abstract:

    Resistance in a dual Malathion- and permethrin-resistant head louse strain (BR-HL) was studied. BR-HL was 3.6- and 3.7-fold more resistant to Malathion and permethrin, respectively, compared to insecticide-susceptible EC-HL. S,S,S-Tributylphosphorotrithioate synergized Malathion toxicity by 2.1-fold but not permethrin toxicity in BR-HL. Piperonyl butoxide did not synergize Malathion or permethrin toxicity. Malathion carboxylesterase (MCE) activity was 13.3-fold and general esterase activity was 3.9-fold higher in BRHL versus EC-HL. There were no significant differences in phosphotriesterase, glutathione S-transferase, and acetylcholinesterase activities between strains. There was no differential sensitivity in acetylcholinesterase inhibition by malaoxon. Esterases from BR-HL had higher affinities and hydrolysis efficiencies versus EC-HL using various naphthyl-substituted esters. Protein content of BR-HL females and males was 1.6- and 1.3-fold higher, respectively, versus EC-HL adults. Electrophoresis revealed two esterases with increased intensity and a unique esterase associated with BR-HL. Thus, increased MCE activity and over-expressed esterases appear to be involved in Malathion resistance in the head louse.

Kyong Sup Yoon - One of the best experts on this subject based on the ideXlab platform.

  • identification and characterization of an esterase involved in Malathion resistance in the head louse pediculus humanus capitis
    Pesticide Biochemistry and Physiology, 2014
    Co-Authors: Deok Ho Kwon, Kyong Sup Yoon, Marshall J Clark
    Abstract:

    Abstract Enhanced Malathion carboxylesterase (MCE) activity was previously reported to be involved in Malathion resistance in the head louse Pediculus humanus capitis (Gao et al., 2006 [8]). To identify MCE, the transcriptional profiles of all five esterases that had been annotated to be catalytically active were determined and compared between the Malathion-resistant (BR-HL) and Malathion-susceptible (KR-HL) strains of head lice. An esterase gene, designated HLCbE3, exhibited approximately 5.4-fold higher transcription levels, whereas remaining four esterases did not exhibit a significant increase in their transcription in BR-HL, indicating that HLCbE3 may be the putative MCE. Comparison of the entire cDNA sequences of HLCbE3 revealed no sequence differences between the BR-HL and KR-HL strains and suggested that no single nucleotide polymorphism is associated with enhanced MCE activity. Two copies of the HLCbE3 gene were observed in BR-HL, implying that the over-transcription of HLCbE3 is due to the combination of a gene duplication and up-regulated transcription. Knockdown of HLCbE3 expression by RNA interference in the BR-HL strain led to increases in Malathion susceptibility, confirming the identity of HLCbE3 as a MCE responsible for Malathion resistance in the head louse. Phylogenetic analysis suggested that HLCbE3 is a typical dietary esterase and belongs to a clade containing various MCEs involved in Malathion resistance.

  • identification and characterization of an esterase involved in Malathion resistance in the head louse pediculus humanus capitis
    Pesticide Biochemistry and Physiology, 2014
    Co-Authors: Deok Ho Kwon, Kyong Sup Yoon, Marshall J Clark
    Abstract:

    Abstract Enhanced Malathion carboxylesterase (MCE) activity was previously reported to be involved in Malathion resistance in the head louse Pediculus humanus capitis (Gao et al., 2006 [8]). To identify MCE, the transcriptional profiles of all five esterases that had been annotated to be catalytically active were determined and compared between the Malathion-resistant (BR-HL) and Malathion-susceptible (KR-HL) strains of head lice. An esterase gene, designated HLCbE3, exhibited approximately 5.4-fold higher transcription levels, whereas remaining four esterases did not exhibit a significant increase in their transcription in BR-HL, indicating that HLCbE3 may be the putative MCE. Comparison of the entire cDNA sequences of HLCbE3 revealed no sequence differences between the BR-HL and KR-HL strains and suggested that no single nucleotide polymorphism is associated with enhanced MCE activity. Two copies of the HLCbE3 gene were observed in BR-HL, implying that the over-transcription of HLCbE3 is due to the combination of a gene duplication and up-regulated transcription. Knockdown of HLCbE3 expression by RNA interference in the BR-HL strain led to increases in Malathion susceptibility, confirming the identity of HLCbE3 as a MCE responsible for Malathion resistance in the head louse. Phylogenetic analysis suggested that HLCbE3 is a typical dietary esterase and belongs to a clade containing various MCEs involved in Malathion resistance.

  • esterase mediated Malathion resistance in the human head louse pediculus capitis anoplura pediculidae
    Pesticide Biochemistry and Physiology, 2006
    Co-Authors: Kyong Sup Yoon, G C Coles, Richard K. Frisbie, Marshall J Clark
    Abstract:

    Resistance in a dual Malathion- and permethrin-resistant head louse strain (BR-HL) was studied. BR-HL was 3.6- and 3.7-fold more resistant to Malathion and permethrin, respectively, compared to insecticide-susceptible EC-HL. S,S,S-Tributylphosphorotrithioate synergized Malathion toxicity by 2.1-fold but not permethrin toxicity in BR-HL. Piperonyl butoxide did not synergize Malathion or permethrin toxicity. Malathion carboxylesterase (MCE) activity was 13.3-fold and general esterase activity was 3.9-fold higher in BRHL versus EC-HL. There were no significant differences in phosphotriesterase, glutathione S-transferase, and acetylcholinesterase activities between strains. There was no differential sensitivity in acetylcholinesterase inhibition by malaoxon. Esterases from BR-HL had higher affinities and hydrolysis efficiencies versus EC-HL using various naphthyl-substituted esters. Protein content of BR-HL females and males was 1.6- and 1.3-fold higher, respectively, versus EC-HL adults. Electrophoresis revealed two esterases with increased intensity and a unique esterase associated with BR-HL. Thus, increased MCE activity and over-expressed esterases appear to be involved in Malathion resistance in the head louse.

  • esterase mediated Malathion resistance in the human head louse pediculus capitis anoplura pediculidae
    Pesticide Biochemistry and Physiology, 2006
    Co-Authors: Kyong Sup Yoon, G C Coles, Richard K. Frisbie, Marshall J Clark
    Abstract:

    Resistance in a dual Malathion- and permethrin-resistant head louse strain (BR-HL) was studied. BR-HL was 3.6- and 3.7-fold more resistant to Malathion and permethrin, respectively, compared to insecticide-susceptible EC-HL. S,S,S-Tributylphosphorotrithioate synergized Malathion toxicity by 2.1-fold but not permethrin toxicity in BR-HL. Piperonyl butoxide did not synergize Malathion or permethrin toxicity. Malathion carboxylesterase (MCE) activity was 13.3-fold and general esterase activity was 3.9-fold higher in BRHL versus EC-HL. There were no significant differences in phosphotriesterase, glutathione S-transferase, and acetylcholinesterase activities between strains. There was no differential sensitivity in acetylcholinesterase inhibition by malaoxon. Esterases from BR-HL had higher affinities and hydrolysis efficiencies versus EC-HL using various naphthyl-substituted esters. Protein content of BR-HL females and males was 1.6- and 1.3-fold higher, respectively, versus EC-HL adults. Electrophoresis revealed two esterases with increased intensity and a unique esterase associated with BR-HL. Thus, increased MCE activity and over-expressed esterases appear to be involved in Malathion resistance in the head louse.

Deok Ho Kwon - One of the best experts on this subject based on the ideXlab platform.

  • identification and characterization of an esterase involved in Malathion resistance in the head louse pediculus humanus capitis
    Pesticide Biochemistry and Physiology, 2014
    Co-Authors: Deok Ho Kwon, Kyong Sup Yoon, Marshall J Clark
    Abstract:

    Abstract Enhanced Malathion carboxylesterase (MCE) activity was previously reported to be involved in Malathion resistance in the head louse Pediculus humanus capitis (Gao et al., 2006 [8]). To identify MCE, the transcriptional profiles of all five esterases that had been annotated to be catalytically active were determined and compared between the Malathion-resistant (BR-HL) and Malathion-susceptible (KR-HL) strains of head lice. An esterase gene, designated HLCbE3, exhibited approximately 5.4-fold higher transcription levels, whereas remaining four esterases did not exhibit a significant increase in their transcription in BR-HL, indicating that HLCbE3 may be the putative MCE. Comparison of the entire cDNA sequences of HLCbE3 revealed no sequence differences between the BR-HL and KR-HL strains and suggested that no single nucleotide polymorphism is associated with enhanced MCE activity. Two copies of the HLCbE3 gene were observed in BR-HL, implying that the over-transcription of HLCbE3 is due to the combination of a gene duplication and up-regulated transcription. Knockdown of HLCbE3 expression by RNA interference in the BR-HL strain led to increases in Malathion susceptibility, confirming the identity of HLCbE3 as a MCE responsible for Malathion resistance in the head louse. Phylogenetic analysis suggested that HLCbE3 is a typical dietary esterase and belongs to a clade containing various MCEs involved in Malathion resistance.

  • identification and characterization of an esterase involved in Malathion resistance in the head louse pediculus humanus capitis
    Pesticide Biochemistry and Physiology, 2014
    Co-Authors: Deok Ho Kwon, Kyong Sup Yoon, Marshall J Clark
    Abstract:

    Abstract Enhanced Malathion carboxylesterase (MCE) activity was previously reported to be involved in Malathion resistance in the head louse Pediculus humanus capitis (Gao et al., 2006 [8]). To identify MCE, the transcriptional profiles of all five esterases that had been annotated to be catalytically active were determined and compared between the Malathion-resistant (BR-HL) and Malathion-susceptible (KR-HL) strains of head lice. An esterase gene, designated HLCbE3, exhibited approximately 5.4-fold higher transcription levels, whereas remaining four esterases did not exhibit a significant increase in their transcription in BR-HL, indicating that HLCbE3 may be the putative MCE. Comparison of the entire cDNA sequences of HLCbE3 revealed no sequence differences between the BR-HL and KR-HL strains and suggested that no single nucleotide polymorphism is associated with enhanced MCE activity. Two copies of the HLCbE3 gene were observed in BR-HL, implying that the over-transcription of HLCbE3 is due to the combination of a gene duplication and up-regulated transcription. Knockdown of HLCbE3 expression by RNA interference in the BR-HL strain led to increases in Malathion susceptibility, confirming the identity of HLCbE3 as a MCE responsible for Malathion resistance in the head louse. Phylogenetic analysis suggested that HLCbE3 is a typical dietary esterase and belongs to a clade containing various MCEs involved in Malathion resistance.

Geraldine Matlock - One of the best experts on this subject based on the ideXlab platform.

  • Randomised, Controlled, Assessor Blind Trial Comparing 4 % Dimeticone Lotion with 0.5 % Malathion Liquid for Head
    2016
    Co-Authors: Louse Infestation, Ian F Burgess, Peter N. Lee, Geraldine Matlock
    Abstract:

    Background. Malathion 0.5 % has been the most prescribed pediculicide in the United Kingdom for around 10 years, and is widely used in Europe and North America. Anecdotal reports suggest Malathion treatments are less effective than formerly, but this has not been confirmed clinically. This study was designed to determine whether Malathion is still effective and if 4% dimeticone lotion is a more effective treatment for head louse infestation. Methodology/Principal Findings. We designed this study as an assessor blinded, randomised, controlled, parallel group trial involving 58 children and 15 adults with active head louse infestation. Each participant received two applications 7 days apart of either 4 % dimeticone lotion, applied for 8 hours or overnight, or 0.5 % Malathion liquid applied for 12 hours or overnight. All treatment and check-up visits were conducted in participants ’ homes. Cure of infestation was defined as no evidence of head lice after the second treatment. Some people were found free from lice but later reinfested. Worst case, intention to treat, analysis found dimeticone was significantly more effective than Malathion, with 30/43 (69.8%) participants cured using dimeticone compared with 10/30 (33.3%) using Malathion (p,0.01, difference 36.4%, 95 % confidence interval 14.7 % to 58.2%). Per protocol analysis showed cure rates of 30/39 (76.9%) and 10/29 (34.5%) respectively. Irritant reactions were observed in only two participants, both treated with Malathion. Conclusions/Significance. We concluded that, although Malathion liquid is still effective for some people, dimeticone lotion offers a significantly more effective alternative treatment for most people. Trial Registration

  • randomised controlled assessor blind trial comparing 4 dimeticone lotion with 0 5 Malathion liquid for head louse infestation
    PLOS ONE, 2007
    Co-Authors: Geraldine Matlock
    Abstract:

    Background Malathion 0.5% has been the most prescribed pediculicide in the United Kingdom for around 10 years, and is widely used in Europe and North America. Anecdotal reports suggest Malathion treatments are less effective than formerly, but this has not been confirmed clinically. This study was designed to determine whether Malathion is still effective and if 4% dimeticone lotion is a more effective treatment for head louse infestation. Methodology/Principal Findings We designed this study as an assessor blinded, randomised, controlled, parallel group trial involving 58 children and 15 adults with active head louse infestation. Each participant received two applications 7 days apart of either 4% dimeticone lotion, applied for 8 hours or overnight, or 0.5% Malathion liquid applied for 12 hours or overnight. All treatment and check-up visits were conducted in participants' homes. Cure of infestation was defined as no evidence of head lice after the second treatment. Some people were found free from lice but later reinfested. Worst case, intention to treat, analysis found dimeticone was significantly more effective than Malathion, with 30/43 (69.8%) participants cured using dimeticone compared with 10/30 (33.3%) using Malathion (p<0.01, difference 36.4%, 95% confidence interval 14.7% to 58.2%). Per protocol analysis showed cure rates of 30/39 (76.9%) and 10/29 (34.5%) respectively. Irritant reactions were observed in only two participants, both treated with Malathion. Conclusions/Significance We concluded that, although Malathion liquid is still effective for some people, dimeticone lotion offers a significantly more effective alternative treatment for most people. Trial Registration Controlled-Trials.com ISRCTN47755726

Richard K. Frisbie - One of the best experts on this subject based on the ideXlab platform.

  • esterase mediated Malathion resistance in the human head louse pediculus capitis anoplura pediculidae
    Pesticide Biochemistry and Physiology, 2006
    Co-Authors: Kyong Sup Yoon, G C Coles, Richard K. Frisbie, Marshall J Clark
    Abstract:

    Resistance in a dual Malathion- and permethrin-resistant head louse strain (BR-HL) was studied. BR-HL was 3.6- and 3.7-fold more resistant to Malathion and permethrin, respectively, compared to insecticide-susceptible EC-HL. S,S,S-Tributylphosphorotrithioate synergized Malathion toxicity by 2.1-fold but not permethrin toxicity in BR-HL. Piperonyl butoxide did not synergize Malathion or permethrin toxicity. Malathion carboxylesterase (MCE) activity was 13.3-fold and general esterase activity was 3.9-fold higher in BRHL versus EC-HL. There were no significant differences in phosphotriesterase, glutathione S-transferase, and acetylcholinesterase activities between strains. There was no differential sensitivity in acetylcholinesterase inhibition by malaoxon. Esterases from BR-HL had higher affinities and hydrolysis efficiencies versus EC-HL using various naphthyl-substituted esters. Protein content of BR-HL females and males was 1.6- and 1.3-fold higher, respectively, versus EC-HL adults. Electrophoresis revealed two esterases with increased intensity and a unique esterase associated with BR-HL. Thus, increased MCE activity and over-expressed esterases appear to be involved in Malathion resistance in the head louse.

  • esterase mediated Malathion resistance in the human head louse pediculus capitis anoplura pediculidae
    Pesticide Biochemistry and Physiology, 2006
    Co-Authors: Kyong Sup Yoon, G C Coles, Richard K. Frisbie, Marshall J Clark
    Abstract:

    Resistance in a dual Malathion- and permethrin-resistant head louse strain (BR-HL) was studied. BR-HL was 3.6- and 3.7-fold more resistant to Malathion and permethrin, respectively, compared to insecticide-susceptible EC-HL. S,S,S-Tributylphosphorotrithioate synergized Malathion toxicity by 2.1-fold but not permethrin toxicity in BR-HL. Piperonyl butoxide did not synergize Malathion or permethrin toxicity. Malathion carboxylesterase (MCE) activity was 13.3-fold and general esterase activity was 3.9-fold higher in BRHL versus EC-HL. There were no significant differences in phosphotriesterase, glutathione S-transferase, and acetylcholinesterase activities between strains. There was no differential sensitivity in acetylcholinesterase inhibition by malaoxon. Esterases from BR-HL had higher affinities and hydrolysis efficiencies versus EC-HL using various naphthyl-substituted esters. Protein content of BR-HL females and males was 1.6- and 1.3-fold higher, respectively, versus EC-HL adults. Electrophoresis revealed two esterases with increased intensity and a unique esterase associated with BR-HL. Thus, increased MCE activity and over-expressed esterases appear to be involved in Malathion resistance in the head louse.