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Biomedical subjects

T H Zhou

Publications and source records attributed to T H Zhou.

At least 37 records · Page 2Linked to original sources
PubMed1996

[Studies on metabolism of 6-chloro butyl phthalide by rat liver microsomes].

The in vitro metabolism of 6-chloro-butyl phthalide (CBP) was studied by rat hepatic microsomes. The constitution of the incubation system was optimized and a RP-HPLC-DAD method was developed for the on-line analysis of CBP and its metabolites. The difference of the metabolism profiles of CBP by rat liver microsomes induced by phenobarbital (PB) and 3-methylcholanthrene (3-MC) was also compared. TLC, column chromatography and preparative HPLC were used for the isolation and purification of the major metabolites and they were identified as (R/S) gamma-hydroxy-CBP and (R/S) beta-hydroxy-CBP by UV, NMR and MS.

Animals↗
PubMed1996

[Studies on metabolism of 6-methoxy butyl phthalide by rat liver microsomes].

The in vitro biotransformation of 6-methoxy butyl phthalide (MBP) by phenobarbital induced rat liver microsomes was investigated by GC/MS and GC/MS with TMS derivatization. Three major metabolites of MBP were identified as 3-OH-MBP, 6-OH-butyl phthalide and gamma-OH-MBP. A less polar metabolite was tentatively identified as an epoxidation product.

Animals↗
PubMed1996

[Investigation on in vivo metabolism of 6-methoxy n-butyl phthalide].

A GC-MS method for the investigation on the metabolism of 6-methoxy n-butyl phthalide (MBP) is described. After oral administration of MBP, the rat urine sample was collected, hydrolyzed with beta-glucuronidase, extracted and concentrated for TMS derivatization, and then analyzed by GC-MS. MBP and its six oxidative metabolites were determined in the 0-24 h rat urine sample. The mass spectra of the metabolites and their derivatives were presented and the in vivo metabolic pathway was discussed.

Animals↗
PubMed1996

[Investigation on in vivo metabolism of n-butyl phthalide].

A GC-MS method for the investigation on the metabolism of n-butyl phthalide (NBP) is described. After oral administration of NBP to rats, urine was collected, hydrolyzed with beta-glucuronidase, extracted and concentrated for TMS derivatization, and then analyzed by GC-MS. HBP and its four oxidative metabolites were determined in 0-24 h, 24-48 h rat urine. The mass spectra of the metabolites and their derivatives were presented and the in vivo metabolic pathway was discussed.

Animals↗
PubMed1993

[Separation and identification of stimulants and their metabolites].

Forty-one stimulant drugs banned by the International Olympic Committee were studied after they were administered to human volunteers. The parent drugs and their metabolites in free or conjugated forms in human urine collected within 24 hours after administration of the drugs were extracted, separated and identified. The separation was performed on a capillary gas chromatograph with nitrogen-phosphorous detector, while the identification was achieved on a capillary gas chromatograph with mass-selective detector. The extract was injected into the gas chromatograph both directly and after derivatization with trifluoroacetic anhydride (TFAA) or N-methyl-N-trimethylsilyl trifluoroacetamide (MSTFA) as well as TFAA and MSTFA combined. The conjugated metabolites were studied after acid hydrolysis of the extract and then selectively derivatized as above. The results are summarized in 4 tables in the text.

Central Nervous System Stimulants↗
PubMed1991

[Studies on the analysis of beta-blocking agents].

A method for the separation and identification of 13 beta-blockers using GC/MS and GC/NPD are described. The TFA and TMS derivatives were prepared by adding TFAA, MSTFA and MBTFA to the standard drugs. The mixture was heated at 65 degrees C for 20 min and chromatographed on FS capillary columns (HP-5). Preliminary results show that the derivatization with MSTFA is better than that with TFAA or MBTFA. There is not much difference between TFAA and MBTFA derivatization. The method is reliable, rapid and simple and may be used to screen these drugs and further applied to the analysis of biological fluids such as plasma and urine.

Adrenergic beta-Antagonists↗
PubMed1991

Study on the doping control method for the detection of narcotic analgesics and beta-blockers.

The analytical method for doping control analysis has been studied. Twenty-nine drugs including eighteen narcotic analgesics, nine beta-blockers, one stimulant and one internal standard were analysed simultaneously by gas chromatograph equipped with a nitrogen-phosphorous detector and gas chromatograph combined with a mass selective detector after derivatization of the drugs.

Adrenergic beta-Antagonists↗
PubMed1991

[Separation of epimers of anisodamine (654-2) with HPLC using chiral additives in the mobile phase].

The separation of epimers of anisodamine were studied with HPLC using a reversed phase ODS C18 column. Several chiral additives were tried in the mobile phases. d-Camphorsulfonic acid and L-(+)-dibutyl tartrate showed good resolution ability for the separation of the isomers, a pair of epimers of anisodamine were well separated; while beta-cyclodextrin appeared to have no selectivity for the epimers.

Chromatography, High Pressure Liquid↗
PubMed1991

[The chromatographic-mass spectrometric analysis and detection of anabolic steroids in human urines and metabolic study].

Nineteen anabolic steroids were separately administered to healthy men. Anabolic steroid metabolites were isolated and extracted from the collected urine samples following an integrated procedure. The main metabolic pathways of these drugs were made clear after the investigation by GC-MS. Based on the obtained chromatographic-mass spectrometric data of anabolic steroids, a method for large scale and routine analysis of anabolic steroids was set up.

Adult↗
PubMed1991

[Investigation on the metabolism of dehydrochloromethyltestosterone in man].

A GC-MS method for the investigation on the metabolism of dehydrochloromethyltestosterone (DHCMT) in man is described. Steroids in human urine were adsorbed on a macroporous XAD-2 resin, eluted with methanol, hydrolyzed with glucuronidase, extracted and concentrated for derivatization and then analyzed with GC-MS. DHCMT and its 7 metabolites were detected in urine samples 8 to 30 h after oral administration. Their structures and the variation of their concentration in urine were determined and the possible metabolic pathways of DHCMT were proposed on the basis of GC-MS feature of its metabolites. The specific metabolites and characteristic ions for screening DHCMT positive urine were chosen. Furthermore, the influence of the sample pretreatment methods on GC-MS results has been studied.

Gas Chromatography-Mass Spectrometry↗
PubMed1991

[GC-MS analysis of norethandrolone and its metabolites in man].

Steroids in human urine were adsorbed on a macroporous XAD-2 resin, eluted with methanol, hydrolyzed with glucuronidase, extracted and concentrated for TMS derivatization and then analyzed with GC-MS. Norethandrolone (N) and its 9 metabolites were detected in urine samples 9-35 h after oral administration. Met-2 and Met-7 could be detected even in 84 h urine sample. The structures of 7 metabolites were elucidated and the variations of their concentration in urine were determined. The specific metabolites and characteristic ions for screening N positive urine were chosen. This method is sensitive enough; the detection limit of N was 10 ng per ml urine, i.e. 10 ppb.

Gas Chromatography-Mass Spectrometry↗
PubMed1991

[Gas chromatographic/mass spectrometric analysis of boldenone urinary metabolites in man].

The metabolism of boldenone (17 beta-hydroxy-1,4-androstem-3-one) in man has been investigated by gas chromatography/mass spectrometry. After oral administration of a 20 mg dose to man, six metabolites were detected in the conjugated fraction of the urinary samples. Boldenone, the major compound excreted in urine, was detected within 34 h after administration. In addition, several metabolites, resulting from the hydroxylation of boldenone and the reduction of the unsaturated carbon bonds of boldenone, were detected in the urine samples varying from 9 to 83 h. Extraction and fractionation of these metabolites were achieved by using XAD-2 column and gas chromatography. The recovery of the whole procedure was studied. Furthermore, the mass spectra of the metabolites are presented and major fragment pathways are discussed.

Gas Chromatography-Mass Spectrometry↗
PubMed1990

[Study on metabolism of phenmetrazine-like drugs and their metabolites].

We have studied the metabolism of phenmetrazine, phendimetrazine and morazone, and their metabolites in urine. A sensitive, specific method using GC/NPD was applied to the determination of the rate of excretion of the drugs quantitatively, diphenylamina being used as the internal standard. The ether extract was derivatized with TFAA reagent, the metabolites and their TFA derivatives were identified by GC/NPD and GC/MSD methods. Norephedrine, cathine, ephedrine and pseudoephedrine in small amount were identified.

Analgesics, Opioid↗
PubMed1989

[Studies on the analysis of some narcotic analgesics and CNS-stimulants].

Procedures for the separation and identification of 12 narcotic analgesics and 2 CNS-stimulants are described using GC/FID, GC/NPD and GC/MSD. The TFA and TMS derivatives were prepared by adding TFAA, MB TFA and MSTFA to the standard drugs. The mixture was heated at 70 degrees C for 30 min and chromatographed on FS capillary columns (SE-54, HP-5). Preliminary results show that all the derivatization with TFAA is better than that with MBTFA, but not much different from MSTFA derivatization. The method is reliable, fast and simple and may be used to screen these drugs and further applied to the analysis of biological fluids such as plasma and urine.

Analgesics, Opioid↗
PubMed1989

[Determination of some androgens and anabolic steroids in human urine by HPLC].

A simple method for determining androgens and anabolic steroids in human urine by HPLC has been developed. The compounds studied are nandrolone, methandienone, testosterone, methyltestosterone, testosterone propionate and nandrolone phenylpropionate. The stationary phase used is C8 bonded silica. Isocratic elution was done with CH3OH-CH3CN-H2O (4:5:6) and programmed flow. Detection limit can be less than 1 ng at the wavelength of 254 nm. The standard curves for each steroid have been set using internal standard (progesterone) and peak height ratio. Linear relationship exists between the ratio and concentration for each steroid. High and stable recovery has been achieved using Sep-Pak C18 cartridges for urine sample clean-up. The operation of the method is simple. The enzymatic hydrolyzation of conjugated steroids in human urine has also been investigated.

Anabolic Agents↗