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T Nambara

Publications and source records attributed to T Nambara.

At least 55 records · Page 3Linked to original sources
PubMed1990

Synthesis of 2-hydroxyestriol monoglucuronides and monosulfates.

The ring A monoglucuronides and monosulfates of 2-hydroxyestriol were synthesized from 2-hydroxyestriol 16,17-diacetate by means of the Koenigs-Knorr reaction with methyl alpha-acetobromoglucuronate and sulfation with sulfur trioxide-pyridine complex, respectively. The conjugated positions of these compounds were definitely established by conversion to 2-hydroxyestriol monomethyl ethers by methylation, then enzymatic hydrolysis. The ring D monoglucuronides and monosulfates of 2-hydroxyestriol were also prepared from 2-hydroxyestriol 2,3-dibenzyl ether by glucuronidation and sulfation in a similar fashion followed by debenzylation, respectively. The positions of conjugation were established on the basis of their 1H-nuclear magnetic resonance spectral data.

Animals↗
PubMed1990

Potential bile acid metabolites. 16. Synthesis of stereoisomeric 3 alpha,6,7,12 alpha-tetrahydroxy-5 beta-cholanoic acids.

New synthetic routes to the four possible stereoisomeric 3 alpha,6,7,12 alpha-tetrahydroxy-5 beta-cholanoic acids (and their methyl esters), one of which (3 alpha,6 alpha 7 beta,12 alpha) is new, and some related compounds are described. In addition, the 5 alpha-epimer of the new acid was obtained. The final products were obtained in high purity for use as reference compounds in the analysis of bile acids in human biologic samples. The results of analysis of the prepared stereoisomers by proton and carbon 13 nuclear magnetic resonance spectroscopies are briefly discussed along with the thin-layer and gas-liquid chromatographic properties.

Bile Acids and Salts↗
PubMed1990

Chemical conversion of corticosteroids to 3 alpha,5 alpha-tetrahydro derivatives. Synthesis of allotetrahydrocortisol glucuronides and allotetrahydrocortisone glucuronides.

The synthesis of the 3- and 21-glucuronides of allotetrahydrocortisol (allo-THF) and allotetrahydrocortisone (allo-THE) is described. 5 alpha-Dihydrocortisol (5) was prepared by selective hydrogenation of 21-acetoxy-3, 11 beta, 17 alpha-trihydroxy-3,5-pregnadien-20-one 3-ethyl ether (3), followed by acid hydrolysis and saponification. When 5 alpha-dihydrocortisol 21-tetrahydropyranyl ether (6) was treated with potassium tri-sec-butylborohydride in tetrahydrofuran under mild conditions, regioselective and stereoselective reduction at C-3 took place to give allo-THF 21-tetrahydropyranyl either (7). This compound was converted into the 3- and 21-monoacetates of allo-THF and allo-THE, key intermediates. Introduction of the glucuronyl residue at C-3 or C-21 was carried out by means of the Koenigs-Knorr reaction. Prior to saponification yielding the 3-glucuronides (20,23), the alkali-sensitive ketol side chain at C-17 was protected as 20-semicarbazones.

Adrenal Cortex Hormones↗
PubMed1989

Studies on steroids. CCXXXXV. Determination of 5 beta-cholestanoic acids in human urine by gas chromatography-mass spectrometry with negative ion chemical ionization detection.

A method for the determination of 3 alpha,7 alpha-dihydroxy-5 beta-cholestanoic acid (DHCA) and 3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholestanoic acid (THCA) in human urine by gas chromatography (GC) in combination with negative ion chemical ionization (NICI) mass spectrometry is described. Unconjugated, glycine- and taurine-conjugated DHCA and THCA labelled with 18O and 2H were used as internal standards. 5 beta-Cholestanoic acids in urine were extracted with a Sep-Pak C18 cartridge, separated into the unconjugated, glycine- and taurine-conjugated fractions by ion-exchange chromatography on piperidinohydroxypropyl Sephadex LH-20 and, following alkaline hydrolysis of conjugated forms, derivatization into the pentafluorobenzyl ester-dimethylethylsilyl ethers. Subsequent resolution of each fraction into DHCA and THCA was attained by GC on a cross-linked 5% phenylmethylsilicone fused-silica capillary column where 5 beta-cholestanoic acids were monitored with a characteristic carboxylate anion [M-181]- in the NICI mode using isobutane as a reagent gas. The method was applied to separation and determination of 5 beta-cholestanoic acids in urine from a patient with Zellweger syndrome and from healthy volunteers.

Bile Acids and Salts↗
PubMed1989

Immobilized enzyme reactors for detection systems in high-performance liquid chromatography.

The applications of immobilized-enzyme reactors (IMERs) to detection systems in high-performance liquid chromatography (HPLC) have been reviewed. A substrate unresponsive to the detector is enzymatically converted to a highly responsive product. The main analytes detected by this system are various steroids, conjugates of various compounds, acetycholine, choline and amino acids. The repetitive use of a single batch of expensive enzyme has economic advantages. On the other hand, the organic modifier in the mobile phase exerts a considerable influence on the activity and stability of the IMER. Usually the activities of the IMER decrease after two or three months of ordinary use. These problems need to be overcome in the future. HPLC-IMER systems are being used in the field of clinical chemistry, and further applications to other fields are expected to be developed.

Chromatography, High Pressure Liquid↗
PubMed1989

Sensitive ferrocene reagents for derivatization of amines for high-performance liquid chromatography with electrochemical detection.

Six reagents possessing ferrocene as an electrophore were prepared and evaluated for pre-column derivatization of amino compounds for their determination by high-performance liquid chromatography with electrochemical detection. The utility of these reagents was investigated employing phenethylamine as a model compound. Among these six, N-succinimidyl 3-ferrocenylpropionate was the best with respect to reactivity, stability and electrochemical properties. The developed method was applied to the determination of putrescine formed from ornithine by ornithine decarboxylase.

Amines↗
PubMed1989

A method for the simultaneous analysis of unconjugated and glycine-conjugated bile acids by capillary gas-liquid chromatography.

A method for the simultaneous analysis of unconjugated and glycine-conjugated bile acids by means of capillary gas-liquid chromatography without need for prior deconjugation is described. The method involves: i) the use of an aluminum-clad fused-silica capillary column coated with a very thin film (0.1 micron) of a highly thermostable bonded and crosslinked methyl polysiloxane, and ii) the analysis of the bile acids as their methyl ester-dimethylethylsilyl ether derivatives. This method, used to separate the major free and glycine-conjugated bile acids from human gall bladder bile, should be applicable for the analysis of other biological fluids.

Bile Acids and Salts↗
PubMed1989

Estrone sulfate and sulfatase activity in human breast cancer and endometrial cancer.

Estrone sulfate (E1-S) in the serum and tissues of patients with breast cancer or endometrial cancer was measured by a direct radioimmunoassay without hydrolysis. The concentration of E1-S in breast cancer tissue was 1.64 +/- 0.28 ng/g wet wt (+/- SE), lower than in surrounding normal breast tissue (4.46 +/- 1.23). Estradiol-17 beta(E2)/E1-S was higher in endometrial cancer tissue than normal endometrial tissue. Estrone sulfatase activity in breast cancer tissue was 0.81 +/- 0.23 nmol/h/mg protein, higher than in surrounding normal breast tissue (0.35 +/- 0.11). These results suggest that E1-S, which is abundant in the peripheral circulation, is hydrolyzed by sulfatase in breast cancer tissue or endometrial cancer tissue and liberates free estrogens, which may stimulate the growth of these malignant tumors.

Adipose Tissue↗
PubMed1989

Sensitivity of steroid enzyme immunoassays. Comparison of four label enzymes in an assay system using a monoclonal anti-steroid antibody.

The sensitivities of monoclonal antibody-based enzyme immunoassays for 11-deoxycortisol using alkaline phosphatase (AP), horseradish peroxidase (HRP), beta-galactosidase (beta-GAL) and glucose oxidase (GOD) as labels were compared. The anti-11-deoxycortisol antibody used was that produced in ascites by inoculating antibody-secreting hybridoma cells into mice. Enzyme labeling of 11-deoxycortisol was carried out by the N-succinimidyl ester method. The activated ester of 4-(2-carboxyethylthio)-11-deoxycortisol was treated with each enzyme to give a homologous enzyme-labeled antigen. In the competitive immunoassay, the bound and free enzyme-labeled antigens were separated by a double antibody method and the enzymic activity of the immune precipitate was determined by colorimetric and fluorimetric methods. The AP activity was measured in three ways, using p-nitrophenyl phosphate, nicotinamide adenine dinucleotide phosphate (NADP), and 4-methylumbelliferyl phosphate as substrates. o-Nitrophenyl beta-D-galactopyranoside and 4-methylumbelliferyl beta-D-galactopyranoside were used for beta-GAL, and 3,3',5,5'-tetramethylbenzidine (TMB) and 3-(p-hydroxyphenyl)propionic acid (HPPA) for HRP. In the case of GOD, TMB and HPPA were used in combination with HRP. A dose-response curve with a high sensitivity was obtained in each 11-deoxycortisol assay system by the use of a minimum amount of the enzyme-labeled antigen at an appropriate dilution of monoclonal anti-11-deoxycortisol antibody (Ka = 2 x 10(10) M-1). The amounts of 11-deoxycortisol needed to displace 50% of the bound label ranged from 5 to 15 pg in the colorimetric methods, and 4-9 pg in the fluorimetric methods.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Monoclonal↗
PubMed1989

Reductive biotransformation of 3-oxo bile acids in human blood.

7 alpha,12 alpha-Dihydroxy-3-oxo-5 beta-cholanoic acid labeled with 18O atoms was incubated with human blood, and the biotransformation products were separated and characterized by gas chromatography-mass spectrometry as the pentafluorobenzyl ester-trimethylsilyl and -dimethylethylsilyl ether derivatives. 3 beta,7 alpha,12 alpha-Trihydroxy-5 beta-cholanoic acid was identified as a main metabolite. When 3-oxo bile acid was incubated with human blood denatured at 70 degrees C for 2 min, no metabolites were formed. The enzymic reduction activity proved to be localized in the red blood cell fraction.

Bile Acids and Salts↗
PubMed1989

Potential bile acid metabolites. XV. Synthesis of 4 beta-hydroxylated bile acids; unique bile acids in human fetal bile.

The 4 beta-hydroxylated derivatives of lithocholic, deoxycholic, chenodeoxycholic, and cholic acids were synthesized from their respective parent compounds. The principal reactions employed were 1) beta-face cis-dihydroxylation of delta 3 intermediates with osmium tetroxide-N-methylmorpholine N-oxide, 2) selective cathylation of vicinal 3 beta,4 beta-diols followed by oxidation of the resulting 4 beta-monocathylates, or direct selective oxidation at C-3 of 3 beta,4 beta-diols with pyridinium chlorochromate, and 3) stereoselective reduction of the 3-oxo compounds with tert-butylamine-borane complex. The results of analysis of the prepared 4 beta-hydroxylated bile acids with a diequatorial trans-glycol structure and their 3 beta-epimers by proton and carbon-13 nuclear magnetic resonance spectroscopies are briefly discussed along with the mass spectrometric properties.

Bile↗
PubMed1989

Determination of 3 beta-hydroxylated bile acids in human serum and liver tissue.

3 beta, 7 alpha-Dihydroxy-5 beta-cholanoic acid (3 beta, 7 alpha-diOH) was detected in serum of 3 patients with intrahepatic cholestasis. 3 beta, 7 beta-dihydroxy-5 beta-cholanoic acid (3 beta, 7 beta-diOH) appeared in serum of those patients after treatment with ursodeoxycholic acid (UDC). These bile acids were also detected in only unconjugated fractions of serum of another 7 patients with chronic liver diseases, but not in liver tissue of them. The liver does not seem to from these bile acids itself because they were absent in liver tissue.

Bile Acids and Salts↗
PubMed1989

Potential bile acid metabolites. 14. Hyocholic and muricholic acid stereoisomers.

The complete set of the eight theoretically possible stereoisomeric 3,6,7-trihydroxy-5 beta-cholanic acids, four of which are new, related to hyocholic and muricholic acids were prepared from chenodeoxycholic acid. The principal reactions used were 1) cis-dihydroxylation of delta 6-compounds with osmium tetroxide/N-methylmorpholine N-oxide; 2) trans-dihydroxylation of 6 alpha, 7 alpha-epoxy compounds with boron trifluoride etherate in N,N-dimethyl-formamide; 3) inversion of equatorial 3 alpha-hydroxylated compounds to the corresponding 3 beta-epimers with diethyl azodicarboxylate/triphenylphosphine/formic acid; and 4) stereoselective reduction of 7-keto derivatives with zinc borohydride (or sodium borohydride) and by metallic potassium/tert-amyl alcohol.

Bile Acids and Salts↗
PubMed1989

Identification of 3 alpha,4 beta,7 alpha-trihydroxy-5 beta-cholanoic acid in human bile: reflection of a new pathway in bile acid metabolism in humans.

The chemical synthesis, nuclear magnetic resonance, and mass spectrometric characteristics of the first C-4 hydroxylated bile acid analogues are described. The data definitively confirm, for the first time, the identity of 3 alpha,4 beta,7 alpha-trihydroxy-5 beta-cholanoic acid in human fetal gallbladder bile. In addition, 3 alpha,4 beta,7 alpha-12 alpha-tetrahydroxy-5 beta-cholanoic was identified in the feces from healthy newborn infants many days after birth, indicating a hepatic origin for C-4 hydroxylation of bile acids. To our knowledge bile acids hydroxylated at the C-4 position of the steroid nucleus have never been previously recognized in any mammalian species. The finding of this novel bile acid which accounts for 5-15% of the total biliary bile acids in early gestation indicates that C-4 hydroxylation is a unique and important metabolic pathway in early human development.

Bile↗
PubMed1989

The biotransformed metabolite profiles in blood after intravenous administration of dehydrocholic acid.

One gram of dehydrocholic acid was injected intravenously into two patients with percutaneous transhepatic cholangial drainage, and the biotransformed metabolites profiles over a 120-min period in serum and bile were analyzed. In serum unconjugated 3 alpha-hydroxy-7,12-dioxo-cholanoic acid (3 alpha-OH-7,12-OXO) acid was markedly increased after the injection of dehydrocholic acid, and reached about 80 microM within 30 min. On the other hand, conjugated 3 alpha, 7 alpha-dihydroxy-12-oxo-cholanoic acid (3 alpha,7 alpha-OH-12-OXO) was consecutively increased with lag time to an elevation of 3 alpha-OH-7,12-OXO. In bile, the major constituent of metabolites was conjugated 3 alpha,7 alpha-OH-12-OXO (more than 90% of the excreted metabolites), while conjugated 3 alpha-OH-7,12-OXO was detected as minor constituent. Therefore, between bile and serum, there was great difference in biotransformed metabolites profiles. The mechanism of elevation of unconjugated 3 alpha-OH-7,12-OXO in serum remains obscure, but this new finding raised a question as to whether organ-reducing 3-keto group of dehydrocholic acid is restricted to the liver.

Aged↗
PubMed1988

Studies on steroids. CCXXXVIII. Determination of bile acids in liver tissue by gas chromatography-mass spectrometry with negative ion chemical ionization detection.

A method for the determination of bile acids in 2-10 mg of human liver tissue by gas chromatography (GC) in combination with negative ion chemical ionization (NICI) mass spectrometry is described. Unconjugated, glycine- and taurine-conjugated bile acids labelled with 18O and 2H were used as internal standards. The preparation of these compounds was attained by the exchange reaction of the carbonyl group with H218O, followed by metal hydride reduction. Bile acids in solubilized liver tissue were extracted with a Sep-Pak C18 cartridge, separated into the unconjugated, glycine- and taurine-conjugated fractions by ion-exchange chromatography on piperidinohydroxypropyl-Sephadex LH-20 and then derivatized to the pentafluorobenzyl ester-dimethylethylsilyl ethers. Subsequent resolution of each fraction into lithocholate, deoxycholate, chenodeoxycholate, ursodeoxycholate and cholate was attained by GC on a cross-linked 5% phenylmethyl silicone fused-silica capillary column where bile acids were monitored with a characteristic carboxylate anion [M - 181]-in the NICI mode using isobutane as a reagent gas. The newly developed method was applied to the quantitation of bile acids in liver tissue with satisfactory sensitivity and reliability.

Bile Acids and Salts↗