The Experts below are selected from a list of 45636 Experts worldwide ranked by ideXlab platform
Patricia E Ganey - One of the best experts on this subject based on the ideXlab platform.
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a mouse model of severe Halothane hepatitis based on human risk factors
Journal of Pharmacology and Experimental Therapeutics, 2010Co-Authors: Christine M Dugan, Allen E Macdonald, Robert A Roth, Patricia E GaneyAbstract:Halothane (2-bromo-2-chloro-1,1,1-trifluoro-ethane) is an inhaled anesthetic that induces severe, idiosyncratic liver injury, i.e., “Halothane hepatitis,” in approximately 1 in 20,000 human patients. We used known human risk factors (female sex, adult age, and genetics) as well as probable risk factors (fasting and inflammatory stress) to develop a murine model with characteristics of human Halothane hepatitis. Female and male BALB/cJ mice treated with Halothane developed dose-dependent liver injury within 24 h; however, the liver injury was severe only in females. Livers had extensive centrilobular necrosis, inflammatory cell infiltrate, and steatosis. Fasting rendered mice more sensitive to Halothane hepatotoxicity, and 8-week-old female mice were more sensitive than males of the same age or than younger (4-week-old) females. C57BL/6 mice were insensitive to Halothane, suggesting a strong genetic predisposition. In Halothane-treated females, plasma concentration of tumor necrosis factor-α was greater than in males, and neutrophils were recruited to liver more rapidly and to a greater extent. Anti-CD18 serum attenuated Halothane-induced liver injury in female mice, suggesting that neutrophil migration, activation, or both are required for injury. Coexposure of Halothane-treated male mice to lipopolysaccharide to induce modest inflammatory stress converted their mild hepatotoxic response to a pronounced, female-like response. This is the first animal model of an idiosyncratic adverse drug reaction that is based on human risk factors and produces reproducible, severe hepatitis from Halothane exposure with lesions characteristic of human Halothane hepatitis. Moreover, these results suggest that a more robust innate immune response underlies the predisposition of female mice to Halothane hepatitis.
Roderic G. Eckenhoff - One of the best experts on this subject based on the ideXlab platform.
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Halothane an inhalational anesthetic agent increases folding stability of serum albumin
Biochimica et Biophysica Acta, 1999Co-Authors: Jonathan W Tanner, Roderic G. Eckenhoff, Paul A. LiebmanAbstract:Abstract Inhalational anesthetic agents are known to alter protein function, but the nature of the interactions underlying these effects remains poorly understood. We have used differential scanning calorimetry to study the effects of the anesthetic agent Halothane on the thermally induced unfolding transition of bovine serum albumin. We find that Halothane (0.6–10 mM) stabilizes the folded state of this protein, increasing its transition midpoint temperature from 62 to 71°C. Binding of Halothane to the native state of serum albumin thus outweighs any non-specific interactions between the thermally unfolded state of serum albumin and Halothane in this concentration range. Based on the average enthalpy change Δ H for unfolding of 170 kcal/mol, the increase from 62 to 71°C corresponds to an additional Gibbs energy of stabilization (ΔΔ G ) due to Halothane of more than 4 kcal/mol. Analysis of the dependence of ΔΔ G on Halothane concentration shows that thermal unfolding of a bovine serum albumin molecule is linked to the dissociation of about one Halothane molecule at lower Halothane concentrations and about six at higher Halothane concentrations. Serum albumin is the first protein that has been shown to be stabilized by an inhalational anesthetic.
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binding of Halothane to serum albumin demonstrated using tryptophan fluorescence
Anesthesiology, 1995Co-Authors: Jonas S Johansson, Roderic G. Eckenhoff, Leslie P DuttonAbstract:Background : The site of action of general anesthesia remains controversial, but evidence in favor of specific protein target(s) is accumulating. Saturable binding of Halothane to bovine serum albumin (BSA) has recently been reported using photoaffinity labeling and fluorine 19 nuclear magnetic resonance spectroscopy. We report a new approach to study anesthetic binding to soluble proteins, based on native tryptophan fluorescence. Methods : Thymol-free Halothane and fatty acid-free BSA were equilibrated in gas-tight Hamilton syringes and dispensed into stoppered quartz cuvettes at predetermined dilutions. Steady-state fluorescence spectroscopy was used to study their interaction. Results : Halothane quenched the tryptophan fluorescence of BSA in a concentration-dependent, saturable manner with a dissociation constant = 1.8 ± 0.2 mM and a Hill number = 1.0 ± 0.1. The two optical isomers of Halothane bound to BSA with equal affinity. The ability of Halothane to quench BSA tryptophan fluorescence was markedly decreased at pH 3.0 (which causes full uncoiling of BSA), with loss of saturable binding. Diethyl ether displaced a portion of Halothane from its binding sites. Circular dichroism spectroscopy revealed no significant effect of Halothane or diethyl ether on the secondary structure of BSA. Conclusions : The results suggest that Halothane binds in hydrophobic domains containing tryptophan in BSA. This approach may prove useful for studying the interaction of volatile anesthetics and proteins and has the advantage that the location of Halothane in the protein is identified.
Paul A. Liebman - One of the best experts on this subject based on the ideXlab platform.
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Halothane an inhalational anesthetic agent increases folding stability of serum albumin
Biochimica et Biophysica Acta, 1999Co-Authors: Jonathan W Tanner, Roderic G. Eckenhoff, Paul A. LiebmanAbstract:Abstract Inhalational anesthetic agents are known to alter protein function, but the nature of the interactions underlying these effects remains poorly understood. We have used differential scanning calorimetry to study the effects of the anesthetic agent Halothane on the thermally induced unfolding transition of bovine serum albumin. We find that Halothane (0.6–10 mM) stabilizes the folded state of this protein, increasing its transition midpoint temperature from 62 to 71°C. Binding of Halothane to the native state of serum albumin thus outweighs any non-specific interactions between the thermally unfolded state of serum albumin and Halothane in this concentration range. Based on the average enthalpy change Δ H for unfolding of 170 kcal/mol, the increase from 62 to 71°C corresponds to an additional Gibbs energy of stabilization (ΔΔ G ) due to Halothane of more than 4 kcal/mol. Analysis of the dependence of ΔΔ G on Halothane concentration shows that thermal unfolding of a bovine serum albumin molecule is linked to the dissociation of about one Halothane molecule at lower Halothane concentrations and about six at higher Halothane concentrations. Serum albumin is the first protein that has been shown to be stabilized by an inhalational anesthetic.
Christine M Dugan - One of the best experts on this subject based on the ideXlab platform.
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a mouse model of severe Halothane hepatitis based on human risk factors
Journal of Pharmacology and Experimental Therapeutics, 2010Co-Authors: Christine M Dugan, Allen E Macdonald, Robert A Roth, Patricia E GaneyAbstract:Halothane (2-bromo-2-chloro-1,1,1-trifluoro-ethane) is an inhaled anesthetic that induces severe, idiosyncratic liver injury, i.e., “Halothane hepatitis,” in approximately 1 in 20,000 human patients. We used known human risk factors (female sex, adult age, and genetics) as well as probable risk factors (fasting and inflammatory stress) to develop a murine model with characteristics of human Halothane hepatitis. Female and male BALB/cJ mice treated with Halothane developed dose-dependent liver injury within 24 h; however, the liver injury was severe only in females. Livers had extensive centrilobular necrosis, inflammatory cell infiltrate, and steatosis. Fasting rendered mice more sensitive to Halothane hepatotoxicity, and 8-week-old female mice were more sensitive than males of the same age or than younger (4-week-old) females. C57BL/6 mice were insensitive to Halothane, suggesting a strong genetic predisposition. In Halothane-treated females, plasma concentration of tumor necrosis factor-α was greater than in males, and neutrophils were recruited to liver more rapidly and to a greater extent. Anti-CD18 serum attenuated Halothane-induced liver injury in female mice, suggesting that neutrophil migration, activation, or both are required for injury. Coexposure of Halothane-treated male mice to lipopolysaccharide to induce modest inflammatory stress converted their mild hepatotoxic response to a pronounced, female-like response. This is the first animal model of an idiosyncratic adverse drug reaction that is based on human risk factors and produces reproducible, severe hepatitis from Halothane exposure with lesions characteristic of human Halothane hepatitis. Moreover, these results suggest that a more robust innate immune response underlies the predisposition of female mice to Halothane hepatitis.
Leslie P Dutton - One of the best experts on this subject based on the ideXlab platform.
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binding of Halothane to serum albumin demonstrated using tryptophan fluorescence
Anesthesiology, 1995Co-Authors: Jonas S Johansson, Roderic G. Eckenhoff, Leslie P DuttonAbstract:Background : The site of action of general anesthesia remains controversial, but evidence in favor of specific protein target(s) is accumulating. Saturable binding of Halothane to bovine serum albumin (BSA) has recently been reported using photoaffinity labeling and fluorine 19 nuclear magnetic resonance spectroscopy. We report a new approach to study anesthetic binding to soluble proteins, based on native tryptophan fluorescence. Methods : Thymol-free Halothane and fatty acid-free BSA were equilibrated in gas-tight Hamilton syringes and dispensed into stoppered quartz cuvettes at predetermined dilutions. Steady-state fluorescence spectroscopy was used to study their interaction. Results : Halothane quenched the tryptophan fluorescence of BSA in a concentration-dependent, saturable manner with a dissociation constant = 1.8 ± 0.2 mM and a Hill number = 1.0 ± 0.1. The two optical isomers of Halothane bound to BSA with equal affinity. The ability of Halothane to quench BSA tryptophan fluorescence was markedly decreased at pH 3.0 (which causes full uncoiling of BSA), with loss of saturable binding. Diethyl ether displaced a portion of Halothane from its binding sites. Circular dichroism spectroscopy revealed no significant effect of Halothane or diethyl ether on the secondary structure of BSA. Conclusions : The results suggest that Halothane binds in hydrophobic domains containing tryptophan in BSA. This approach may prove useful for studying the interaction of volatile anesthetics and proteins and has the advantage that the location of Halothane in the protein is identified.
