The Experts below are selected from a list of 312 Experts worldwide ranked by ideXlab platform
Norie Murayama - One of the best experts on this subject based on the ideXlab platform.
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involvement of human cytochrome p450 2b6 in the ω and 4 hydroxylation of the Anesthetic Agent propofol
Xenobiotica, 2007Co-Authors: Norie Murayama, M Minoshima, Makiko Shimizu, F P Guengerich, Hiroshi YamazakiAbstract:Human liver microsomal cytochrome P450s (P450s or CYP) involved in the oxidative biotransformation of the Anesthetic Agent propofol were investigated. Of six cDNA-expressed human P450 enzymes tested, CYP2B6 and CYP1A2, followed by CYP3A4, had high catalytic activities at a 20 µM propofol concentration, corresponding to clinical plasma levels. Km and kcat values for propofol ω- and 4-hydroxyation were 27 µM and 21 nmol ω-hydroxypropofol formed/min/nmol CYP2B6 and 30 µM and 42 nmol 4-hydroxypropofol formed/min/nmol CYP2B6, respectively. CYP2B6 expressed in HepG2 cells also effectively catalyzed propofol ω- and 4-hydroxylation. In a panel of individual human liver microsomes, propofol ω- and 4-hydroxylation activities (at the substrate concentration of 20 µM) were highly correlated with CYP2B6 contents, and moderately with CYP3A4 contents. Anti-CYP2B6 antibody inhibited both ω- and 4-hydroxylation activities in human liver samples that contained relatively high levels of CYP2B6, whereas α-naphthoflavone and ...
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rat cytochrome p450 2c11 in liver microsomes involved in oxidation of Anesthetic Agent propofol and deactivated by prior treatment with propofol
Drug Metabolism and Disposition, 2006Co-Authors: Hiroshi Yamazaki, Makiko Shimizu, Takashi Nagashima, Masaki Minoshima, Norie MurayamaAbstract:Propofol (2,6-diisopropylphenol) is a widely-used Anesthetic Agent attributable to its rapid biotransformation. Liver microsomal cytochrome P450 (P450) isoforms involved in the biotransformation of propofol in rats and the effects of propofol in vivo on P450 levels in rats were investigated. Of six cDNA-expressed rat P450 isoforms tested, CYP2B1 and CYP2C11 had high catalytic activities from 5 μM and 20 μM propofol concentrations, respectively. Rates of propofol metabolism, at a substrate concentration of 20 μM based on the reported human blood concentration, were decreased by intraperitoneal treatment of propofol with male rats, in contrast to a strong induction by phenobarbital. Single intravenously administered propofol (10 mg/kg) caused the decrease of total P450 and CYP2C contents and activities of testosterone 16α-hydroxylation and propofol metabolism in liver microsomes from male rats. The suppressive effects were caused by administered propofol (10 mg/kg) twice every 4 h on CYP2B activities such as testosterone 16β-hydroxylation or pentoxyresorufin O-depentylation, in addition to the strong suppression of CYP2C function by the single propofol treatment. These results suggest that CYP2C11, presumably deactivated by propofol, has an important role in propofol metabolism in rat liver microsomes. Repeated administration of propofol could markedly decrease the biotransformation of propofol via P450 deactivation.
Victoria W Y Wong - One of the best experts on this subject based on the ideXlab platform.
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comparison of lidocaine 2 gel versus amethocaine as the sole Anesthetic Agent for strabismus surgery
Ophthalmology, 2003Co-Authors: Christopher B O Yu, Victoria W Y WongAbstract:Abstract Purpose To compare the efficacy of lidocaine 2% gel with amethocaine 1% eyedrops as the sole Anesthetic Agent for one-stage adjustable suture strabismus surgery. Design Prospective, double-masked randomized trial. Participants Fourteen consecutive patients scheduled to undergo bilateral and symmetrical strabismus surgery under topical anesthesia in one institution. Methods Each patient was randomized to receive lidocaine 2% gel in one eye and amethocaine 1% eyedrops in the other eye as the sole Anesthetic Agent for surgery. Masking of the patient and surgeon was ensured by administration of a placebo gel and eyedrop as part of the regimen. Pain and discomfort were assessed via a 10-cm visual analog scale. Main outcome measures Subjective pain and discomfort perceived during surgery were assessed separately by the patient and the surgeon, and the need for any additional anesthesia was recorded. Results A total of 14 subjects indicated mean pain and discomfort scores of 2.6 and 3.2 respectively, for lidocaine gel, and 5.3 and 6.2, respectively, for amethocaine drops ( P = 0.01). The mean number of additional drops required by eyes randomized to lidocaine gel was 0.3, compared with 1.6 for amethocaine drops ( P = 0.02). Conclusions In terms of pain control, lidocaine 2% gel alone is a superior topical Anesthetic for one-stage adjustable suture strabismus surgery when compared with amethocaine 1% eyedrops.
Hiroshi Yamazaki - One of the best experts on this subject based on the ideXlab platform.
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involvement of human cytochrome p450 2b6 in the ω and 4 hydroxylation of the Anesthetic Agent propofol
Xenobiotica, 2007Co-Authors: Norie Murayama, M Minoshima, Makiko Shimizu, F P Guengerich, Hiroshi YamazakiAbstract:Human liver microsomal cytochrome P450s (P450s or CYP) involved in the oxidative biotransformation of the Anesthetic Agent propofol were investigated. Of six cDNA-expressed human P450 enzymes tested, CYP2B6 and CYP1A2, followed by CYP3A4, had high catalytic activities at a 20 µM propofol concentration, corresponding to clinical plasma levels. Km and kcat values for propofol ω- and 4-hydroxyation were 27 µM and 21 nmol ω-hydroxypropofol formed/min/nmol CYP2B6 and 30 µM and 42 nmol 4-hydroxypropofol formed/min/nmol CYP2B6, respectively. CYP2B6 expressed in HepG2 cells also effectively catalyzed propofol ω- and 4-hydroxylation. In a panel of individual human liver microsomes, propofol ω- and 4-hydroxylation activities (at the substrate concentration of 20 µM) were highly correlated with CYP2B6 contents, and moderately with CYP3A4 contents. Anti-CYP2B6 antibody inhibited both ω- and 4-hydroxylation activities in human liver samples that contained relatively high levels of CYP2B6, whereas α-naphthoflavone and ...
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rat cytochrome p450 2c11 in liver microsomes involved in oxidation of Anesthetic Agent propofol and deactivated by prior treatment with propofol
Drug Metabolism and Disposition, 2006Co-Authors: Hiroshi Yamazaki, Makiko Shimizu, Takashi Nagashima, Masaki Minoshima, Norie MurayamaAbstract:Propofol (2,6-diisopropylphenol) is a widely-used Anesthetic Agent attributable to its rapid biotransformation. Liver microsomal cytochrome P450 (P450) isoforms involved in the biotransformation of propofol in rats and the effects of propofol in vivo on P450 levels in rats were investigated. Of six cDNA-expressed rat P450 isoforms tested, CYP2B1 and CYP2C11 had high catalytic activities from 5 μM and 20 μM propofol concentrations, respectively. Rates of propofol metabolism, at a substrate concentration of 20 μM based on the reported human blood concentration, were decreased by intraperitoneal treatment of propofol with male rats, in contrast to a strong induction by phenobarbital. Single intravenously administered propofol (10 mg/kg) caused the decrease of total P450 and CYP2C contents and activities of testosterone 16α-hydroxylation and propofol metabolism in liver microsomes from male rats. The suppressive effects were caused by administered propofol (10 mg/kg) twice every 4 h on CYP2B activities such as testosterone 16β-hydroxylation or pentoxyresorufin O-depentylation, in addition to the strong suppression of CYP2C function by the single propofol treatment. These results suggest that CYP2C11, presumably deactivated by propofol, has an important role in propofol metabolism in rat liver microsomes. Repeated administration of propofol could markedly decrease the biotransformation of propofol via P450 deactivation.
Christopher B O Yu - One of the best experts on this subject based on the ideXlab platform.
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comparison of lidocaine 2 gel versus amethocaine as the sole Anesthetic Agent for strabismus surgery
Ophthalmology, 2003Co-Authors: Christopher B O Yu, Victoria W Y WongAbstract:Abstract Purpose To compare the efficacy of lidocaine 2% gel with amethocaine 1% eyedrops as the sole Anesthetic Agent for one-stage adjustable suture strabismus surgery. Design Prospective, double-masked randomized trial. Participants Fourteen consecutive patients scheduled to undergo bilateral and symmetrical strabismus surgery under topical anesthesia in one institution. Methods Each patient was randomized to receive lidocaine 2% gel in one eye and amethocaine 1% eyedrops in the other eye as the sole Anesthetic Agent for surgery. Masking of the patient and surgeon was ensured by administration of a placebo gel and eyedrop as part of the regimen. Pain and discomfort were assessed via a 10-cm visual analog scale. Main outcome measures Subjective pain and discomfort perceived during surgery were assessed separately by the patient and the surgeon, and the need for any additional anesthesia was recorded. Results A total of 14 subjects indicated mean pain and discomfort scores of 2.6 and 3.2 respectively, for lidocaine gel, and 5.3 and 6.2, respectively, for amethocaine drops ( P = 0.01). The mean number of additional drops required by eyes randomized to lidocaine gel was 0.3, compared with 1.6 for amethocaine drops ( P = 0.02). Conclusions In terms of pain control, lidocaine 2% gel alone is a superior topical Anesthetic for one-stage adjustable suture strabismus surgery when compared with amethocaine 1% eyedrops.
Shihlin Hung - One of the best experts on this subject based on the ideXlab platform.
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active 433 mhz w uhf rf powered chip integrated with a nanocomposite m mwcnt polypyrrole sensor for wireless monitoring of volatile Anesthetic Agent sevoflurane
Sensors and Actuators A-physical, 2008Co-Authors: Murthy Chavali, Ren Jang Wu, Shihlin HungAbstract:Tiny remote sensors capable of monitoring gases and vapors are having greatest demand due to their potential applications in diverse research fields. In the present work, design and fabrication of an active wireless UHF (433 MHz) RF-powered sensing system for monitoring volatile organic compounds is presented. The developed sensor chip consists of a thin film of gas-responsive composite material, based on modified multiwalled carbon nanotubes (m-MWCNTs) and polypyrrole (Ppy), coated over two comb-like interdigitated gold electrodes. Wireless modules have been integrated with the chemical sensor chip (composite m-MWCNTs/Ppy) and RF components to detect volatile Anesthetic Agent, fluoromethyl 2,2,2,-trifluoro-1-(trifluoromethyl) ethyl ether (sevoflurane) is demonstrated.
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new sensing technology for detection of the common inhalational Anesthetic Agent sevoflurane using conducting polypyrrole films
Sensors and Actuators B-chemical, 2007Co-Authors: Ren Jang Wu, Murthy Chavali, Yu Ching Huang, Shihlin HungAbstract:Abstract A new type of gas sensor to measure resistance was developed to detect sevoflurane concentrations at room temperature. The measured FTIR spectrum of sevoflurane vapor was given. The sensing material polypyrrole was synthesized in situ by UV-photopolymerization. The relative resistance variation was 3.9 for a sevoflurane concentration of 1.2%. The sensor response time (60 s) and recovery time (20 s) were very short. Molecular dynamic calculations made for sevoflurane adsorption on polypyrrole revealed formation of a new bond, N–H–F. The bond length was predicted to be in the range of 0.2–0.4 nm. The bond energy was about 7.2 kcal/mol. Sensor responses to the concentrations 0.1–10% were 1.57–5.9, respectively.
