The Experts below are selected from a list of 189 Experts worldwide ranked by ideXlab platform
Yuji Nakahara - One of the best experts on this subject based on the ideXlab platform.
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determination of triazolam involving its hydroxy metabolites in Hair shaft and Hair Root by reversed phase liquid chromatography with electrospray ionization mass spectrometry and application to human Hair analysis
Analytical Biochemistry, 2001Co-Authors: Toshimasa Toyooka, Masayoshi Kanbori, Yusuke Kumaki, Yuji NakaharaAbstract:A sensitive method using reversed-phase liquid chromatography coupled with electrospray ionization mass spectrometry has been developed for simultaneous determination of triazolam and its hydroxy metabolites in Hair. After the addition of deuterium-labeled 1-hydroxymethyltriazolam as an internal standard, the analytes in Hair shaft and Hair Root samples were extracted with a basic medium, CH2Cl2:MeOH:28% NH4OH (20:80:2) at room temperature overnight. The chromatographic separation of the analytes was achieved using a semimicro HPLC column (3-μm particle size; 100 × 2.0-mm i.d.) by gradient elution with acetonitrile in water containing 1% acetic acid as eluent. The mass spectrometer was operated in selected-ion monitoring mode at quasi-molecular ions [M+H]+ of triazolam and its metabolites. The method has been applied to determine the incorporation of triazolam and its metabolites into the Hair shafts and Hair Roots of Dark Agouti rats administered 3 or 6 mg/kg triazolam intraperitoneally twice a day for 5 days. Triazolam, 1-hydroxymethyltriazolam, and 4-hydroxytriazolam were incorporated into the Hair shafts and the Hair Roots. The concentration of 4-hydroxytriazolam was the highest of all compounds detected. An unknown substance considered to be 1,4-dihydroxytriazolam also appeared in the Hair samples. The structural elucidation was performed with online HPLC-MS after acetylation of the substance with acetic anhydride and pyridine. The time course studies of triazolam and the metabolites in both rat Hair Roots and plasma were carried out after single intraperitoneal administration of triazolam. The concentrations of triazolam and the metabolites in the Hair Roots reflected those in the plasma. The proposed method using selected-reaction monitoring was applied to the determination of triazolam and the metabolites in human Hairs of a triazolam addict. Triazolam, 1-hydroxymethyltriazolam, and 4-hydroxytriazolam were identified in the black Hair shafts, whereas only triazolam was detected in the Hair Roots and the white Hair shafts. This is the first report on the detection of triazolam and its metabolites in human Hairs.
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Detection of Triazolam and Its Hydroxy Metabolites in Rat Hair by Reversed-Phase Liquid Chromatography with Electrospray Ionization Mass Spectrometry
Journal of analytical toxicology, 2000Co-Authors: Toshimasa Toyo'oka, Masayoshi Kanbori, Yusuke Kumaki, Taketsune Miyahara, Yuji NakaharaAbstract:A sensitive method using reversed-phase liquid chromatography coupled with electrospray ionization mass spectrometry (LC-ESI-MS) for simultaneous determination of triazolam (TZ) and its hydroxy metabolites in Hair has been developed. After the addition of deuterium-labeled 1 -hydroxymethyltriazolam (1-HT-d4) as an internal standard, analytes in Hair shaft and Hair Root samples were extracted with a basic medium, CH2Cl2/MeOH/28% NH4OH (20:80:2), at room temperature overnight. The chromatographic separation of the analytes was achieved using a 3-microm micro HPLC column (100 x 2.0-mm i.d.) with a gradient of acetonitrile in water containing 1% acetic acid as the mobile phase at a flow rate of 0.15 mL/min. The mass spectrometer was operated in selected-ion monitoring mode at quasi molecular ions [M+H]+ of TZ and its metabolites. Under the proposed conditions, the ranges of quantitation of TZ, 1-HT, and 4-HT were 0.1-10 ng/0.2 mL. The method has been applied to determine the Hair shaft and Hair Root incorporation of TZ and its metabolites into Dark Agouti rats administered with 3 mg/kg or 6 mg/kg intraperitoneally twice a day for five days. Judging from the retention behavior by the chromatography and the mass spectra of the peaks detected, TZ, 1-HT, and 4-HT were incorporated in the Hair shaft and the Hair Root. The concentration of 4-HT was the highest of all compounds detected. An unknown substance thought to be 1,4-diHT also appeared in both Hair shaft and Hair Root samples. This substance was obtained from in vitro metabolic studies of TZ using rat liver microsome fraction and was accompanied by the other two metabolites, 1-HT and 4-HT. Structural elucidation was performed with online high-performance liquid chromatography-MS after acetylation of the substance with acetic anhydride and pyridine. This is the first report of the detection of the hydroxy metabolites of TZ in Hair. The method has been found to be useful as a screening procedure of TZ intake in humans.
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Hair analysis for drugs of abuse XX. Incorporation and behaviors of seven methamphetamine homologs in the rat Hair Root
Life sciences, 1998Co-Authors: Yuji Nakahara, Ruri Kikura, Kazunori TakahashiAbstract:Abstract To elucidate drug disposition in Hair, the incorporation and retention behavior of 7 phenethylamines in the rat Hair Root were investigated: methamphetamine(MA), 3,4-methylenedioxymethamphetamine(MDMA), benzphetamine(BZP), ephedrine(EP), N,N-dimethylamphetamine(DMA), p-nitro-methamphetamine(NO2MA), and N-acetyl-methamphetamine(AcMA). On day 10 after shaving the Hair on the back of the rats, drug was intraperitoneally administered at a single dose of 10 mg/kg to Long Evans rats (which were male and 6 weeks of age), possessing black and white Hair, and the back Hair that grew was collected by plucking with Hair nippers at 0.083 h (5 min), 0.25 h, 0.5 h, 1h, 2 h, 4 h, 6h, 9 h, 24 h, 33 h and 48 H. After washing the plucked Hairs three times with 0.1% sodium dodecylsulfate, the amount of drug in each of the Hair Root samples was analyzed by a selected ion monitoring of gas chromatography mass spectrometry (GC-MS) analysis. The times at which the concentration of each drug in the Hair Root samples reached the peak concentration, ranged between 3.30 and 41.51 ng/mg. For each drug, the point of time at which the largest positive incremental change in drug concentration was seen, ranged between 5 min and 1 h, for all of the drugs except for AcMA which was hardly incorporated in the rat Hair. The data showed that there are mainly 4 modes in which a drug becomes incorporated into the black Hair Root: rapid and prolonged incorporation (NO2MA, MDMA), rapid and short incorporation(MA, DMA), slow and prolonged incorporation(BZP, EP), slow and short incorporation, which includes hardly any incorporation (AcMA). As all seven drugs were hardly incorporated into the white Hair, it was concluded that the combination of melanin and basic compounds is essential for a drug to become incorporated into Hair. Our results suggest that a portion of the drugs in the Hair Root is accumulated in the Hair shaft, and the remaining portion is redistributed outside the Hair shaft. The second finding is that the concentration of drug incorporated into Hair mainly depends on two processes — (1)the drug incorporation into Hair and the drug retention in Hair.
P.c.m. Van De Kerkhof - One of the best experts on this subject based on the ideXlab platform.
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The Hair Root pattern after calcipotriol treatment for scalp psoriasis.
Acta dermato-venereologica, 1995Co-Authors: A.l.a. Kuijpers, H.m.j. Van Baar, M.w. Van Gasselt, P.c.m. Van De KerkhofAbstract:Scalp psoriasis is associated with Hair loss and an increased telogen/anagen ratio. Topical treatment of scalp psoriasis (with corticosteroids, dithranol or tar) results in decreased scaling, induration and erythema of the plaques. Calcipotriol is effective in the treatment of psoriasis vulgaris. However, the potent growth-inhibiting potential of this compound might theoretically induce Hair loss. A study was designed to find out to what extent calcipotriol treatment modulates the percentage of anagen and telogen Hair during treatment of scalp psoriasis. A group of 26 patients participated in a placebo-controlled dose-finding study on the efficacy of calcipotriol in scalp psoriasis. Hair plucks before and after treatment were taken. The telogen/anagen ratio remained unaffected during 6 weeks of calcipotriol treatment. No correlation was demonstrated between efficacy of treatment and quantification of telogen/anagen ratio. It can be concluded that the growth-inhibiting potential of calcipotriol is not reflected in the in vivo Hair growth pattern during calcipotriol treatment.
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The Hair Root pattern in psoriasis of the scalp.
Acta dermato-venereologica, 1992Co-Authors: W J Schoorl, H.m.j. Van Baar, P.c.m. Van De KerkhofAbstract:Several reports suggest that a localized effluvium of scalp Hair may occur in patients with psoriasis. The percentages of telogen and catagen Hair have been claimed to be normal or increased in isolated cases. In the present study the anagen/telogen ratio was quantified under standardized conditions in psoriatic plaques and uninvolved areas of the scalp in 22 patients and the scalp of 22 normal controls. This assessment was carried out by light microscopic analysis of Hair Roots, obtained by the Hair pluck-method. A consistent increase in the percentages of telogen and catagen Hair was shown in psoriatic plaques, compared with the uninvolved areas. Compared with the scalp of normal controls, this percentage was significantly increased in psoriatic plaques, but not in the uninvolved areas.
Masayoshi Kanbori - One of the best experts on this subject based on the ideXlab platform.
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determination of triazolam involving its hydroxy metabolites in Hair shaft and Hair Root by reversed phase liquid chromatography with electrospray ionization mass spectrometry and application to human Hair analysis
Analytical Biochemistry, 2001Co-Authors: Toshimasa Toyooka, Masayoshi Kanbori, Yusuke Kumaki, Yuji NakaharaAbstract:A sensitive method using reversed-phase liquid chromatography coupled with electrospray ionization mass spectrometry has been developed for simultaneous determination of triazolam and its hydroxy metabolites in Hair. After the addition of deuterium-labeled 1-hydroxymethyltriazolam as an internal standard, the analytes in Hair shaft and Hair Root samples were extracted with a basic medium, CH2Cl2:MeOH:28% NH4OH (20:80:2) at room temperature overnight. The chromatographic separation of the analytes was achieved using a semimicro HPLC column (3-μm particle size; 100 × 2.0-mm i.d.) by gradient elution with acetonitrile in water containing 1% acetic acid as eluent. The mass spectrometer was operated in selected-ion monitoring mode at quasi-molecular ions [M+H]+ of triazolam and its metabolites. The method has been applied to determine the incorporation of triazolam and its metabolites into the Hair shafts and Hair Roots of Dark Agouti rats administered 3 or 6 mg/kg triazolam intraperitoneally twice a day for 5 days. Triazolam, 1-hydroxymethyltriazolam, and 4-hydroxytriazolam were incorporated into the Hair shafts and the Hair Roots. The concentration of 4-hydroxytriazolam was the highest of all compounds detected. An unknown substance considered to be 1,4-dihydroxytriazolam also appeared in the Hair samples. The structural elucidation was performed with online HPLC-MS after acetylation of the substance with acetic anhydride and pyridine. The time course studies of triazolam and the metabolites in both rat Hair Roots and plasma were carried out after single intraperitoneal administration of triazolam. The concentrations of triazolam and the metabolites in the Hair Roots reflected those in the plasma. The proposed method using selected-reaction monitoring was applied to the determination of triazolam and the metabolites in human Hairs of a triazolam addict. Triazolam, 1-hydroxymethyltriazolam, and 4-hydroxytriazolam were identified in the black Hair shafts, whereas only triazolam was detected in the Hair Roots and the white Hair shafts. This is the first report on the detection of triazolam and its metabolites in human Hairs.
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Detection of Triazolam and Its Hydroxy Metabolites in Rat Hair by Reversed-Phase Liquid Chromatography with Electrospray Ionization Mass Spectrometry
Journal of analytical toxicology, 2000Co-Authors: Toshimasa Toyo'oka, Masayoshi Kanbori, Yusuke Kumaki, Taketsune Miyahara, Yuji NakaharaAbstract:A sensitive method using reversed-phase liquid chromatography coupled with electrospray ionization mass spectrometry (LC-ESI-MS) for simultaneous determination of triazolam (TZ) and its hydroxy metabolites in Hair has been developed. After the addition of deuterium-labeled 1 -hydroxymethyltriazolam (1-HT-d4) as an internal standard, analytes in Hair shaft and Hair Root samples were extracted with a basic medium, CH2Cl2/MeOH/28% NH4OH (20:80:2), at room temperature overnight. The chromatographic separation of the analytes was achieved using a 3-microm micro HPLC column (100 x 2.0-mm i.d.) with a gradient of acetonitrile in water containing 1% acetic acid as the mobile phase at a flow rate of 0.15 mL/min. The mass spectrometer was operated in selected-ion monitoring mode at quasi molecular ions [M+H]+ of TZ and its metabolites. Under the proposed conditions, the ranges of quantitation of TZ, 1-HT, and 4-HT were 0.1-10 ng/0.2 mL. The method has been applied to determine the Hair shaft and Hair Root incorporation of TZ and its metabolites into Dark Agouti rats administered with 3 mg/kg or 6 mg/kg intraperitoneally twice a day for five days. Judging from the retention behavior by the chromatography and the mass spectra of the peaks detected, TZ, 1-HT, and 4-HT were incorporated in the Hair shaft and the Hair Root. The concentration of 4-HT was the highest of all compounds detected. An unknown substance thought to be 1,4-diHT also appeared in both Hair shaft and Hair Root samples. This substance was obtained from in vitro metabolic studies of TZ using rat liver microsome fraction and was accompanied by the other two metabolites, 1-HT and 4-HT. Structural elucidation was performed with online high-performance liquid chromatography-MS after acetylation of the substance with acetic anhydride and pyridine. This is the first report of the detection of the hydroxy metabolites of TZ in Hair. The method has been found to be useful as a screening procedure of TZ intake in humans.
Yusuke Kumaki - One of the best experts on this subject based on the ideXlab platform.
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determination of triazolam involving its hydroxy metabolites in Hair shaft and Hair Root by reversed phase liquid chromatography with electrospray ionization mass spectrometry and application to human Hair analysis
Analytical Biochemistry, 2001Co-Authors: Toshimasa Toyooka, Masayoshi Kanbori, Yusuke Kumaki, Yuji NakaharaAbstract:A sensitive method using reversed-phase liquid chromatography coupled with electrospray ionization mass spectrometry has been developed for simultaneous determination of triazolam and its hydroxy metabolites in Hair. After the addition of deuterium-labeled 1-hydroxymethyltriazolam as an internal standard, the analytes in Hair shaft and Hair Root samples were extracted with a basic medium, CH2Cl2:MeOH:28% NH4OH (20:80:2) at room temperature overnight. The chromatographic separation of the analytes was achieved using a semimicro HPLC column (3-μm particle size; 100 × 2.0-mm i.d.) by gradient elution with acetonitrile in water containing 1% acetic acid as eluent. The mass spectrometer was operated in selected-ion monitoring mode at quasi-molecular ions [M+H]+ of triazolam and its metabolites. The method has been applied to determine the incorporation of triazolam and its metabolites into the Hair shafts and Hair Roots of Dark Agouti rats administered 3 or 6 mg/kg triazolam intraperitoneally twice a day for 5 days. Triazolam, 1-hydroxymethyltriazolam, and 4-hydroxytriazolam were incorporated into the Hair shafts and the Hair Roots. The concentration of 4-hydroxytriazolam was the highest of all compounds detected. An unknown substance considered to be 1,4-dihydroxytriazolam also appeared in the Hair samples. The structural elucidation was performed with online HPLC-MS after acetylation of the substance with acetic anhydride and pyridine. The time course studies of triazolam and the metabolites in both rat Hair Roots and plasma were carried out after single intraperitoneal administration of triazolam. The concentrations of triazolam and the metabolites in the Hair Roots reflected those in the plasma. The proposed method using selected-reaction monitoring was applied to the determination of triazolam and the metabolites in human Hairs of a triazolam addict. Triazolam, 1-hydroxymethyltriazolam, and 4-hydroxytriazolam were identified in the black Hair shafts, whereas only triazolam was detected in the Hair Roots and the white Hair shafts. This is the first report on the detection of triazolam and its metabolites in human Hairs.
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Detection of Triazolam and Its Hydroxy Metabolites in Rat Hair by Reversed-Phase Liquid Chromatography with Electrospray Ionization Mass Spectrometry
Journal of analytical toxicology, 2000Co-Authors: Toshimasa Toyo'oka, Masayoshi Kanbori, Yusuke Kumaki, Taketsune Miyahara, Yuji NakaharaAbstract:A sensitive method using reversed-phase liquid chromatography coupled with electrospray ionization mass spectrometry (LC-ESI-MS) for simultaneous determination of triazolam (TZ) and its hydroxy metabolites in Hair has been developed. After the addition of deuterium-labeled 1 -hydroxymethyltriazolam (1-HT-d4) as an internal standard, analytes in Hair shaft and Hair Root samples were extracted with a basic medium, CH2Cl2/MeOH/28% NH4OH (20:80:2), at room temperature overnight. The chromatographic separation of the analytes was achieved using a 3-microm micro HPLC column (100 x 2.0-mm i.d.) with a gradient of acetonitrile in water containing 1% acetic acid as the mobile phase at a flow rate of 0.15 mL/min. The mass spectrometer was operated in selected-ion monitoring mode at quasi molecular ions [M+H]+ of TZ and its metabolites. Under the proposed conditions, the ranges of quantitation of TZ, 1-HT, and 4-HT were 0.1-10 ng/0.2 mL. The method has been applied to determine the Hair shaft and Hair Root incorporation of TZ and its metabolites into Dark Agouti rats administered with 3 mg/kg or 6 mg/kg intraperitoneally twice a day for five days. Judging from the retention behavior by the chromatography and the mass spectra of the peaks detected, TZ, 1-HT, and 4-HT were incorporated in the Hair shaft and the Hair Root. The concentration of 4-HT was the highest of all compounds detected. An unknown substance thought to be 1,4-diHT also appeared in both Hair shaft and Hair Root samples. This substance was obtained from in vitro metabolic studies of TZ using rat liver microsome fraction and was accompanied by the other two metabolites, 1-HT and 4-HT. Structural elucidation was performed with online high-performance liquid chromatography-MS after acetylation of the substance with acetic anhydride and pyridine. This is the first report of the detection of the hydroxy metabolites of TZ in Hair. The method has been found to be useful as a screening procedure of TZ intake in humans.
Toshimasa Toyooka - One of the best experts on this subject based on the ideXlab platform.
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determination of triazolam involving its hydroxy metabolites in Hair shaft and Hair Root by reversed phase liquid chromatography with electrospray ionization mass spectrometry and application to human Hair analysis
Analytical Biochemistry, 2001Co-Authors: Toshimasa Toyooka, Masayoshi Kanbori, Yusuke Kumaki, Yuji NakaharaAbstract:A sensitive method using reversed-phase liquid chromatography coupled with electrospray ionization mass spectrometry has been developed for simultaneous determination of triazolam and its hydroxy metabolites in Hair. After the addition of deuterium-labeled 1-hydroxymethyltriazolam as an internal standard, the analytes in Hair shaft and Hair Root samples were extracted with a basic medium, CH2Cl2:MeOH:28% NH4OH (20:80:2) at room temperature overnight. The chromatographic separation of the analytes was achieved using a semimicro HPLC column (3-μm particle size; 100 × 2.0-mm i.d.) by gradient elution with acetonitrile in water containing 1% acetic acid as eluent. The mass spectrometer was operated in selected-ion monitoring mode at quasi-molecular ions [M+H]+ of triazolam and its metabolites. The method has been applied to determine the incorporation of triazolam and its metabolites into the Hair shafts and Hair Roots of Dark Agouti rats administered 3 or 6 mg/kg triazolam intraperitoneally twice a day for 5 days. Triazolam, 1-hydroxymethyltriazolam, and 4-hydroxytriazolam were incorporated into the Hair shafts and the Hair Roots. The concentration of 4-hydroxytriazolam was the highest of all compounds detected. An unknown substance considered to be 1,4-dihydroxytriazolam also appeared in the Hair samples. The structural elucidation was performed with online HPLC-MS after acetylation of the substance with acetic anhydride and pyridine. The time course studies of triazolam and the metabolites in both rat Hair Roots and plasma were carried out after single intraperitoneal administration of triazolam. The concentrations of triazolam and the metabolites in the Hair Roots reflected those in the plasma. The proposed method using selected-reaction monitoring was applied to the determination of triazolam and the metabolites in human Hairs of a triazolam addict. Triazolam, 1-hydroxymethyltriazolam, and 4-hydroxytriazolam were identified in the black Hair shafts, whereas only triazolam was detected in the Hair Roots and the white Hair shafts. This is the first report on the detection of triazolam and its metabolites in human Hairs.
