The Experts below are selected from a list of 3234 Experts worldwide ranked by ideXlab platform
E. M. P. J. Garrido - One of the best experts on this subject based on the ideXlab platform.
-
electrochemical sensor for simultaneous determination of herbicide MCPA and its metabolite 4 chloro 2 methylphenol application to photodegradation environmental monitoring
2015Co-Authors: V. Rahemi, Jorge Garrido, Fernanda Borges, Christopher M.a. Brett, E. M. P. J. GarridoAbstract:The development and application of a polyaniline/carbon nanotube (CNT) cyclodextrin matrix (PANI-β-CD/MWCNT)-based electrochemical sensor for the quantitative determination of the herbicide 4-chloro-2-methylphenoxyacetic acid (MCPA) and its main transformation product 4-chloro-2-methylphenol in natural waters are described. A simple cyclic voltammetry-based electrochemical methodology, in phosphate buffer solution at pH 6.0, was used to develop a method to determine both MCPA and 4-chloro-2-methylphenol, without any previous extraction or derivatization steps. A linear concentration range (10 to 50 μmol L−1) and detection limits of 1.1 and 1.9 μmol L−1, respectively, were achieved using optimized cyclic voltammetric parameters. The proposed method was successfully applied to the determination of MCPA and 4-chloro-2-methylphenol in natural water samples with satisfactory recoveries (94 to 107 %) and in good agreement with the results obtained by an established high-performance liquid chromatography technique, no significant differences being found between the methods. Interferences from ionic species and other herbicides used for broad-leaf weed control were shown to be small. The newly developed methodology was also successfully applied to MCPA photodegradation environmental studies.
-
Enhanced host-guest electrochemical recognition of herbicide MCPA using a β-cyclodextrin carbon nanotube sensor.
2012Co-Authors: V. Rahemi, Jorge Garrido, Fernanda Borges, J.j. Vandamme, Christopher M.a. Brett, E. M. P. J. GarridoAbstract:An electrochemical sensor for the determination of the chlorophenoxy herbicide MCPA has been developed, based on a combination of multi-walled carbon nanotubes with incorporated β-cyclodextrin and a polyaniline film modified glassy carbon electrode. The proposed molecular host-guest recognition based sensor has a high electrochemical sensitivity for the determination of MCPA. The electrochemical behaviour of MCPA at the chemically modified electrode was investigated in detail by cyclic voltammetry. The results indicate that the β-CD/MWCNT modified glassy carbon electrode exhibits efficient electrocatalytic oxidation of MCPA with high sensitivity, stability and lifetime. The analytical characteristics of this film were used for the quantitative determination of MCPA in natural waters. Cyclic voltammetry in phosphate buffer solution at pH 6.0, allowed the development of a method to determine MCPA, without any previous steps of extraction, clean-up, or derivatization, in the range of 10-100 μmol L(-1), with a detection limit of 0.99 μmol L(-1) in water. The results were statistically compared with those obtained through an established high-performance liquid chromatography technique, no significant differences having been found between the two methods.
Darren M Roberts - One of the best experts on this subject based on the ideXlab platform.
-
toxicokinetics including saturable protein binding of 4 chloro 2 methyl phenoxyacetic acid MCPA in patients with acute poisoning
2011Co-Authors: Darren M Roberts, Lalith Senarathna, Andrew H Dawson, Fahim Mohamed, Ron Cheng, Geoffrey K Eaglesham, Nicholas A BuckleyAbstract:Human data on protein binding and dose-dependent changes in toxicokinetics for MCPA are very limited. 128 blood samples were obtained in 49 patients with acute MCPA poisoning and total and unbound concentrations of MCPA were determined. The Scatchard plot was biphasic suggesting protein binding to two sites. The free MCPA concentration increased when the total concentration exceeded 239 mg/L (95% confidence interval 198–274 mg/L). Nonlinear regression using a two-site binding hyperbola model estimated saturation of the high affinity binding site at 115 mg/L (95%CI 0–304). Further analyses using global fitting of serial data and adjusting for the concentration of albumin predicted similar concentrations for saturable binding (184 mg/L and 167 mg/L, respectively) without narrowing the 95%CI. In 25 patients, the plasma concentration–time curves for both bound and unbound MCPA were approximately log-linear which may suggest first order elimination, although sampling was infrequent so zero order elimination cannot be excluded. Using a cut-off concentration of 200 mg/L, the half-life of MCPA at higher concentrations was 25.5 h (95%CI 15.0–83.0 h; n = 16 patients) compared to 16.8 h (95%CI 13.6–22.2 h; n = 10 patients) at lower concentrations. MCPA is subject to saturable protein binding but the influence on half-life appears marginal.
-
intentional self poisoning with the chlorophenoxy herbicide 4 chloro 2 methylphenoxyacetic acid MCPA
2005Co-Authors: Darren M Roberts, Nicholas A Buckley, Ruwan Seneviratne, Fahim Mohammed, Renu Patel, Lalith Senarathna, Ariyasena Hittarage, Andrew H Dawson, Michael EddlestonAbstract:Study objective Data on poisoning with MCPA (4-chloro-2-methyl-phenoxyacetic acid) are limited to 6 case reports. Our objective is to describe outcomes from intentional self-poisoning with MCPA in a prospective case series of 181 patients presenting to hospitals in Sri Lanka. Methods Patient information was collected by on-site study physicians as part of an ongoing prospective cohort study of poisoned patients. Medical history, clinical details, and blood samples were obtained prospectively. Results Overall clinical toxicity was minimal in 85% of patients, including mild gastrointestinal symptoms in 44% of patients. More severe clinical signs of chlorophenoxy poisoning reported previously, such as rhabdomyolysis, renal dysfunction, and coma, also occurred but were uncommon. Eight patients died (4.4%). Most deaths occurred suddenly from cardiorespiratory arrest within 48 hours of poisoning; the pathophysiological mechanism of death was not apparent. The correlation between admission plasma MCPA concentration and clinical markers of severity of toxicity (physical signs, symptoms, and increased creatine kinase level) was poor. Conclusion Intentional self-poisoning with MCPA generally causes mild toxicity, but cardiorespiratory arrest and death may occur. All patients should receive routine resuscitation and supportive care. It seems reasonable to correct acidosis and maintain an adequate urine output, but there is insufficient evidence to support other specific interventions. Our data do not support a clinical role for measurement of plasma MCPA in the acute management of poisoning, and insufficient data were available to fully examine the utility of measured electrolytes and creatine kinase levels.
-
intentional self poisoning with the chlorophenoxy herbicide 4 chloro 2 methylphenoxyacetic acid MCPA
2005Co-Authors: Darren M Roberts, Nicholas A Buckley, Ruwan Seneviratne, Fahim Mohammed, Renu Patel, Lalith Senarathna, Ariyasena Hittarage, Andrew H Dawson, Michael EddlestonAbstract:Study objective Data on poisoning with MCPA (4-chloro-2-methyl-phenoxyacetic acid) are limited to 6 case reports. Our objective is to describe outcomes from intentional self-poisoning with MCPA in a prospective case series of 181 patients presenting to hospitals in Sri Lanka. Methods Patient information was collected by on-site study physicians as part of an ongoing prospective cohort study of poisoned patients. Medical history, clinical details, and blood samples were obtained prospectively. Results Overall clinical toxicity was minimal in 85% of patients, including mild gastrointestinal symptoms in 44% of patients. More severe clinical signs of chlorophenoxy poisoning reported previously, such as rhabdomyolysis, renal dysfunction, and coma, also occurred but were uncommon. Eight patients died (4.4%). Most deaths occurred suddenly from cardiorespiratory arrest within 48 hours of poisoning; the pathophysiological mechanism of death was not apparent. The correlation between admission plasma MCPA concentration and clinical markers of severity of toxicity (physical signs, symptoms, and increased creatine kinase level) was poor. Conclusion Intentional self-poisoning with MCPA generally causes mild toxicity, but cardiorespiratory arrest and death may occur. All patients should receive routine resuscitation and supportive care. It seems reasonable to correct acidosis and maintain an adequate urine output, but there is insufficient evidence to support other specific interventions. Our data do not support a clinical role for measurement of plasma MCPA in the acute management of poisoning, and insufficient data were available to fully examine the utility of measured electrolytes and creatine kinase levels.
Andrew H Dawson - One of the best experts on this subject based on the ideXlab platform.
-
toxicokinetics including saturable protein binding of 4 chloro 2 methyl phenoxyacetic acid MCPA in patients with acute poisoning
2011Co-Authors: Darren M Roberts, Lalith Senarathna, Andrew H Dawson, Fahim Mohamed, Ron Cheng, Geoffrey K Eaglesham, Nicholas A BuckleyAbstract:Human data on protein binding and dose-dependent changes in toxicokinetics for MCPA are very limited. 128 blood samples were obtained in 49 patients with acute MCPA poisoning and total and unbound concentrations of MCPA were determined. The Scatchard plot was biphasic suggesting protein binding to two sites. The free MCPA concentration increased when the total concentration exceeded 239 mg/L (95% confidence interval 198–274 mg/L). Nonlinear regression using a two-site binding hyperbola model estimated saturation of the high affinity binding site at 115 mg/L (95%CI 0–304). Further analyses using global fitting of serial data and adjusting for the concentration of albumin predicted similar concentrations for saturable binding (184 mg/L and 167 mg/L, respectively) without narrowing the 95%CI. In 25 patients, the plasma concentration–time curves for both bound and unbound MCPA were approximately log-linear which may suggest first order elimination, although sampling was infrequent so zero order elimination cannot be excluded. Using a cut-off concentration of 200 mg/L, the half-life of MCPA at higher concentrations was 25.5 h (95%CI 15.0–83.0 h; n = 16 patients) compared to 16.8 h (95%CI 13.6–22.2 h; n = 10 patients) at lower concentrations. MCPA is subject to saturable protein binding but the influence on half-life appears marginal.
-
intentional self poisoning with the chlorophenoxy herbicide 4 chloro 2 methylphenoxyacetic acid MCPA
2005Co-Authors: Darren M Roberts, Nicholas A Buckley, Ruwan Seneviratne, Fahim Mohammed, Renu Patel, Lalith Senarathna, Ariyasena Hittarage, Andrew H Dawson, Michael EddlestonAbstract:Study objective Data on poisoning with MCPA (4-chloro-2-methyl-phenoxyacetic acid) are limited to 6 case reports. Our objective is to describe outcomes from intentional self-poisoning with MCPA in a prospective case series of 181 patients presenting to hospitals in Sri Lanka. Methods Patient information was collected by on-site study physicians as part of an ongoing prospective cohort study of poisoned patients. Medical history, clinical details, and blood samples were obtained prospectively. Results Overall clinical toxicity was minimal in 85% of patients, including mild gastrointestinal symptoms in 44% of patients. More severe clinical signs of chlorophenoxy poisoning reported previously, such as rhabdomyolysis, renal dysfunction, and coma, also occurred but were uncommon. Eight patients died (4.4%). Most deaths occurred suddenly from cardiorespiratory arrest within 48 hours of poisoning; the pathophysiological mechanism of death was not apparent. The correlation between admission plasma MCPA concentration and clinical markers of severity of toxicity (physical signs, symptoms, and increased creatine kinase level) was poor. Conclusion Intentional self-poisoning with MCPA generally causes mild toxicity, but cardiorespiratory arrest and death may occur. All patients should receive routine resuscitation and supportive care. It seems reasonable to correct acidosis and maintain an adequate urine output, but there is insufficient evidence to support other specific interventions. Our data do not support a clinical role for measurement of plasma MCPA in the acute management of poisoning, and insufficient data were available to fully examine the utility of measured electrolytes and creatine kinase levels.
-
intentional self poisoning with the chlorophenoxy herbicide 4 chloro 2 methylphenoxyacetic acid MCPA
2005Co-Authors: Darren M Roberts, Nicholas A Buckley, Ruwan Seneviratne, Fahim Mohammed, Renu Patel, Lalith Senarathna, Ariyasena Hittarage, Andrew H Dawson, Michael EddlestonAbstract:Study objective Data on poisoning with MCPA (4-chloro-2-methyl-phenoxyacetic acid) are limited to 6 case reports. Our objective is to describe outcomes from intentional self-poisoning with MCPA in a prospective case series of 181 patients presenting to hospitals in Sri Lanka. Methods Patient information was collected by on-site study physicians as part of an ongoing prospective cohort study of poisoned patients. Medical history, clinical details, and blood samples were obtained prospectively. Results Overall clinical toxicity was minimal in 85% of patients, including mild gastrointestinal symptoms in 44% of patients. More severe clinical signs of chlorophenoxy poisoning reported previously, such as rhabdomyolysis, renal dysfunction, and coma, also occurred but were uncommon. Eight patients died (4.4%). Most deaths occurred suddenly from cardiorespiratory arrest within 48 hours of poisoning; the pathophysiological mechanism of death was not apparent. The correlation between admission plasma MCPA concentration and clinical markers of severity of toxicity (physical signs, symptoms, and increased creatine kinase level) was poor. Conclusion Intentional self-poisoning with MCPA generally causes mild toxicity, but cardiorespiratory arrest and death may occur. All patients should receive routine resuscitation and supportive care. It seems reasonable to correct acidosis and maintain an adequate urine output, but there is insufficient evidence to support other specific interventions. Our data do not support a clinical role for measurement of plasma MCPA in the acute management of poisoning, and insufficient data were available to fully examine the utility of measured electrolytes and creatine kinase levels.
Nicholas A Buckley - One of the best experts on this subject based on the ideXlab platform.
-
toxicokinetics including saturable protein binding of 4 chloro 2 methyl phenoxyacetic acid MCPA in patients with acute poisoning
2011Co-Authors: Darren M Roberts, Lalith Senarathna, Andrew H Dawson, Fahim Mohamed, Ron Cheng, Geoffrey K Eaglesham, Nicholas A BuckleyAbstract:Human data on protein binding and dose-dependent changes in toxicokinetics for MCPA are very limited. 128 blood samples were obtained in 49 patients with acute MCPA poisoning and total and unbound concentrations of MCPA were determined. The Scatchard plot was biphasic suggesting protein binding to two sites. The free MCPA concentration increased when the total concentration exceeded 239 mg/L (95% confidence interval 198–274 mg/L). Nonlinear regression using a two-site binding hyperbola model estimated saturation of the high affinity binding site at 115 mg/L (95%CI 0–304). Further analyses using global fitting of serial data and adjusting for the concentration of albumin predicted similar concentrations for saturable binding (184 mg/L and 167 mg/L, respectively) without narrowing the 95%CI. In 25 patients, the plasma concentration–time curves for both bound and unbound MCPA were approximately log-linear which may suggest first order elimination, although sampling was infrequent so zero order elimination cannot be excluded. Using a cut-off concentration of 200 mg/L, the half-life of MCPA at higher concentrations was 25.5 h (95%CI 15.0–83.0 h; n = 16 patients) compared to 16.8 h (95%CI 13.6–22.2 h; n = 10 patients) at lower concentrations. MCPA is subject to saturable protein binding but the influence on half-life appears marginal.
-
intentional self poisoning with the chlorophenoxy herbicide 4 chloro 2 methylphenoxyacetic acid MCPA
2005Co-Authors: Darren M Roberts, Nicholas A Buckley, Ruwan Seneviratne, Fahim Mohammed, Renu Patel, Lalith Senarathna, Ariyasena Hittarage, Andrew H Dawson, Michael EddlestonAbstract:Study objective Data on poisoning with MCPA (4-chloro-2-methyl-phenoxyacetic acid) are limited to 6 case reports. Our objective is to describe outcomes from intentional self-poisoning with MCPA in a prospective case series of 181 patients presenting to hospitals in Sri Lanka. Methods Patient information was collected by on-site study physicians as part of an ongoing prospective cohort study of poisoned patients. Medical history, clinical details, and blood samples were obtained prospectively. Results Overall clinical toxicity was minimal in 85% of patients, including mild gastrointestinal symptoms in 44% of patients. More severe clinical signs of chlorophenoxy poisoning reported previously, such as rhabdomyolysis, renal dysfunction, and coma, also occurred but were uncommon. Eight patients died (4.4%). Most deaths occurred suddenly from cardiorespiratory arrest within 48 hours of poisoning; the pathophysiological mechanism of death was not apparent. The correlation between admission plasma MCPA concentration and clinical markers of severity of toxicity (physical signs, symptoms, and increased creatine kinase level) was poor. Conclusion Intentional self-poisoning with MCPA generally causes mild toxicity, but cardiorespiratory arrest and death may occur. All patients should receive routine resuscitation and supportive care. It seems reasonable to correct acidosis and maintain an adequate urine output, but there is insufficient evidence to support other specific interventions. Our data do not support a clinical role for measurement of plasma MCPA in the acute management of poisoning, and insufficient data were available to fully examine the utility of measured electrolytes and creatine kinase levels.
-
intentional self poisoning with the chlorophenoxy herbicide 4 chloro 2 methylphenoxyacetic acid MCPA
2005Co-Authors: Darren M Roberts, Nicholas A Buckley, Ruwan Seneviratne, Fahim Mohammed, Renu Patel, Lalith Senarathna, Ariyasena Hittarage, Andrew H Dawson, Michael EddlestonAbstract:Study objective Data on poisoning with MCPA (4-chloro-2-methyl-phenoxyacetic acid) are limited to 6 case reports. Our objective is to describe outcomes from intentional self-poisoning with MCPA in a prospective case series of 181 patients presenting to hospitals in Sri Lanka. Methods Patient information was collected by on-site study physicians as part of an ongoing prospective cohort study of poisoned patients. Medical history, clinical details, and blood samples were obtained prospectively. Results Overall clinical toxicity was minimal in 85% of patients, including mild gastrointestinal symptoms in 44% of patients. More severe clinical signs of chlorophenoxy poisoning reported previously, such as rhabdomyolysis, renal dysfunction, and coma, also occurred but were uncommon. Eight patients died (4.4%). Most deaths occurred suddenly from cardiorespiratory arrest within 48 hours of poisoning; the pathophysiological mechanism of death was not apparent. The correlation between admission plasma MCPA concentration and clinical markers of severity of toxicity (physical signs, symptoms, and increased creatine kinase level) was poor. Conclusion Intentional self-poisoning with MCPA generally causes mild toxicity, but cardiorespiratory arrest and death may occur. All patients should receive routine resuscitation and supportive care. It seems reasonable to correct acidosis and maintain an adequate urine output, but there is insufficient evidence to support other specific interventions. Our data do not support a clinical role for measurement of plasma MCPA in the acute management of poisoning, and insufficient data were available to fully examine the utility of measured electrolytes and creatine kinase levels.
Avniel Singh Ghuman - One of the best experts on this subject based on the ideXlab platform.
-
multi connection pattern analysis decoding the representational content of neural communication
2017Co-Authors: Avniel Singh Ghuman, Yuanning Li, Robert M RichardsonAbstract:Abstract The lack of multivariate methods for decoding the representational content of interregional neural communication has left it difficult to know what information is represented in distributed brain circuit interactions. Here we present Multi-Connection Pattern Analysis (MCPA), which works by learning mappings between the activity patterns of the populations as a factor of the information being processed. These maps are used to predict the activity from one neural population based on the activity from the other population. Successful MCPA-based decoding indicates the involvement of distributed computational processing and provides a framework for probing the representational structure of the interaction. Simulations demonstrate the efficacy of MCPA in realistic circumstances. In addition, we demonstrate that MCPA can be applied to different signal modalities to evaluate a variety of hypothesis associated with information coding in neural communications. We apply MCPA to fMRI and human intracranial electrophysiological data to provide a proof-of-concept of the utility of this method for decoding individual natural images and faces in functional connectivity data. We further use a MCPA-based representational similarity analysis to illustrate how MCPA may be used to test computational models of information transfer among regions of the visual processing stream. Thus, MCPA can be used to assess the information represented in the coupled activity of interacting neural circuits and probe the underlying principles of information transformation between regions.
-
Multi-Connection Pattern Analysis: Decoding the Representational Content of Neural Communication
2016Co-Authors: Avniel Singh GhumanAbstract:What information is represented in the interactions between neural populations is unknown due to the lack of multivariate methods for decoding the representational content of neural communication. Here we present Multi-Connection Pattern Analysis (MCPA), which probes the involvement of distributed computational processing and probe the representational structure of neural interactions. MCPA learns mappings between the activity patterns as a factor of the information being processed. These maps are used to predict the multivariate activity pattern from one neural population based on the activity pattern from another population. Simulations demonstrate the efficacy of MCPA in realistic circumstances. Applying MCPA to fMRI data shows that interactions between visual cortex regions are sensitive to information that distinguishes individual natural images. These results suggest that image individuation occurs through interactive computation across the visual processing network. Thus, MCPA can be used to assess the information processed in the coupled activity of interacting neural circuits.