Highly simplified method for gas-liquid chromatographic quantitation of bile acids and sterols in human stool. (1/156)

A simple method for the gas-liquid chromatographic quantitation of human fecal bile acids and sterols is described where bile acids are subjected to n-butyl ester derivatization, without prior isolation from the stool, followed by trimethylsilylation of the sterols and bile acids. Under these conditions, bile acid derivatives are well resolved from each other and from the trimethylsilyl ether derivatives of fecal sterols and no overlap occurs. The method was shown to be highly reproducible and recoveries were similar to those obtained with other methods used for fecal bile acid analysis. Application of the method for bile acid and sterol analysis in human stool is described.  (+info)

Determination of opiates and cocaine in hair as trimethylsilyl derivatives using gas chromatography-tandem mass spectrometry. (2/156)

An analytical method for the determination of heroin, 6-monoacetylmorphine, morphine, codeine, cocaine, benzoylecgonine, and cocaethylene in human hair using gas chromatography-tandem mass spectrometry is presented. The analytes were extracted from finely cut hair with methanol at 56 degrees C for 18 h in the presence of nalorphine as the internal standard. After the incubation, methanol was evaporated to dryness, and all the analytes, except heroin, cocaine, and cocaethylene, were converted to their trimethylsilyl derivatives. The reaction products were identified and quantitated using product ions formed from the parent ions by collision-induced dissociation in the ion-trap mass spectrometer. This method provided excellent sensitivity and specificity for analytes at the concentrations usually found in the keratin matrix.  (+info)

Identification of testosterone and testosterone esters in human hair. (3/156)

In 1974, steroids were added to the list of doping agents banned by the International Olympic Committee because of their effects on the performance of the athletes. Testosterone and its esters promote the development of secondary male sexual characteristics and accelerate muscle growth. The mandatory test to detect testosterone abuse is to measure the ratio of testosterone to epitestosterone in the urine. However, because athletes can adjust their dosage to stay within the range permitted, there is a risk of test evasion. Therefore, we developed two original procedures to determine testosterone and its esters in human hair. First, testosterone was investigated in hair obtained from 26 control subjects. After decontamination with dichloromethane, 100 mg of hair was incubated in 1 M NaOH in the presence of 1 ng of testosterone-d3. After neutralization, the extract was purified using solid-phase extraction with Isolute C18 columns followed by liquid-liquid extraction with pentane. After silylation, testosterone was analyzed by gas chromatography-mass spectrometry. Concentrations were in the range 1.2 to 11.4 pg/mg with a mean value of 3.8 pg/mg. To distinguish exogenous abuse from endogenous levels, the incorporation of testosterone esters into hair was investigated. Preparation involved methanolic incubation to avoid the cleavage of the esters. In a panel of eight esters, it was possible to identify testosterone propionate, testosterone enanthate, and testosterone decanoate in the hair of two bodybuilders and one weight lifter. This new technology may find useful applications in anabolic abuse control.  (+info)

Inhibition of angiogenesis and intrahepatic growth of colon cancer by TAC-101. (4/156)

We demonstrated in this study that inhibition of intra-hepatic growth of colon cancer by TAC-101 is mediated by inhibition of angiogenesis. In vitro experiments showed that TAC-101 inhibited the proliferation of murine hepatic sinusoidal endothelial (HSE) cells induced by coculture with murine colon 26-L5 (L5) cells. HSE cell proliferation was also enhanced by conditioned medium of L5 cells (CM-L5), and this enhancement of proliferation was abrogated by anti-vascular endothelial growth factor antibody. CM-L5 also induced in vitro tube formation of HSE cells on Matri-gel, and this activity of CM-L5 was abrogated by TAC-101 in a concentration-dependent manner. On the other hand, p.o. administration of TAC-101 inhibited tumor-induced angiogenesis in vivo and decreased the weights of L5 tumors in the mouse liver. Reverse transcriptase-PCR analysis using in vivo tumor tissue suggested that repression of vascular endothelial growth factor expression by TAC-101 was associated with the antiangiogenic activity. TAC-101 alone and 5-fluorouracil (5-FU)/D,L-leucovorin (LV) significantly inhibited the intrahepatic growth of L5 tumors (P = 0.002 and 0.001, respectively), whereas 5-FU alone did not (P = 0.088). When TAC-101 was administered with 5-FU/LV, marked enhancement of antitumor activity was observed (95% inhibition; P<0.001). This enhanced antitumor effect was also observed in experiments using Co-3 human colon adenocarcinoma. Concurrent treatment with TAC-101 and 5-FU/LV and sequential treatment with 5-FU/LV followed by TAC-101 resulted in significant augmentation of antitumor activity against Co-3 (overall P = 0.007 and 0.015, respectively). These findings indicate that TAC-101 inhibits tumor angiogenesis and suggest that it may be effective against hepatic metastasis of colon cancer.  (+info)

Analysis of trimethylsilyl derivatization products of phosphatidylethanol by gas chromatography-mass spectrometry. (5/156)

For the detection of rare phospholipid, phosphatidylethanol (PEt), GC-MS analysis method was adopted for the detection of derivatization products of PEt by N,O-bis (trimethylsilyl) trifluroacetamide (BSTFA). A re-structured molecule derived from PEt, ethyl bis (trimethylsilyl)-phosphate was found from search of Wiley database. This molecule can be used as a marker for PEt analysis. The molecular formula was C8H23O4PSi2 and weight of the formula was 270.09.  (+info)

Use of high-resolution open tubular glass capillary columns to separate acidic metabolites in urine. (6/156)

We used high-resolution glass capillary columns to study the trimethylsilyl derivatives of some acidic metabolites found in pooled urine specimens form control and postpartum subjects. About 30 compounds were identified by gas chromatography-mass spectrometry-computer techniques. In general, open tubular capillary columns effect better resolution of trimethylsilyl derivatives of organic acids than do conventional packed columns. GESE-30 proved to be a good general-purpose stationary phase, whereas OV-17 offered certain advantages in resolving aromatic acid components.  (+info)

Improved resolution of natural diacylglycerols by gas-liquid chromatography on polar siloxanes. (7/156)

A new cyanoalkylphenylsiloxane (SILAR 5CP) liquid phase is shown to possess sufficient polarity to permit improved GC separations of natural diacylglycerols based on unsaturation and positional placement of fatty acids as well as on molecular weight, which was previously possible only on ethylene glycol succinate polyesters. Unlike the polyesters, the polar siloxane polymer has moderate thermal stability and provides GC columns which can be used for several months without replacing the packing. The GC analyses were made with conventional columns containing 3% SILAR 5CP on Gas Chrom Q at 270 degrees C isothermally. The diacylglycerols were chromatographed as the TMS ethers. Excellent seperations were obtained for the 1,2(2,3)- and 1,3-diacyglycerols derived from corn, linseed, peanut and cod liver oils and for the 1,2-diacyl-sn-glycerols from hepatic glycerophospholipids.  (+info)

Hair analysis for pharmaceutical drugs. II. Effective extraction and determination of sildenafil (Viagra) and its N-desmethyl metabolite in rat and human hair by GC-MS. (8/156)

In order to study the incorporation of sildenafil (SDF) and its N-demethylated metabolite (norSDF) into hair, animal model experiments were carried out. After shaving the back hair, SDF was dosed to two sets of three male dark-agouti pigmented rats (5 weeks old) per each group at 25 mg/kg once a day for 5 successive days with intraperitoneal (i.p.) (set1) and oral administration (set2). The regrown back hair was collected 14 d after the first administration. Three typical extraction methods, using methanol-5 M hydrochloric acid, methanol-trifluoroacetic acid and 1 M sodium hydroxide, were evaluated using the rat hair samples containing SDF and norSDF. Methanol-5 M hydrochloric acid was the best extraction method in terms of high efficiency and reproducibility. The extract was purified using Bond Elut Certify columns and was derivatized with trimethylsilylimidazole: N,O-bis(trimethylsilyltrifluoroacetamide): trimethylchlorosilane (3: 3: 2) at 90 degrees C for 30 min. The trimethylsilylated products were analyzed by GC-MS using selected ion monitoring. SDF and norSDF were simultaneously detected in the rat hair. The hair concentrations were 4.9-6.3 (av. 5.8) ng/mg and 15.6-20.3 (av. 17.6) ng/mg for SDF and norSDF, respectively, with i.p. administration, and 2.6-4.1 (av. 3.6) ng/mg and 8.1-10.4 (av. 9.1) ng/mg with oral administration. The hair concentrations of norSDF were about three times higher than those of SDF, and the ratios of both compounds showed no significant difference between i.p. and oral administrations. This method was applied to the scalp hair of two patients who orally took SDF at regular intervals for the treatment of penile erectile dysfunction. The hair concentrations of SDF and norSDF in the two patients were 19.8 and 55.9 ng/mg, and 1.7 and 5.6 ng/mg, respectively.  (+info)