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Biomedical subjects

T Nambara

Publications and source records attributed to T Nambara.

At least 109 records · Page 6Linked to original sources
PubMed1985

CCXVII. Separation and characterization of bile acid 3-glucuronides in human urine by high-performance liquid chromatography.

The separation and characterization of unconjugated and conjugated bile acid 3-glucuronides in biological fluids without prior deconjugation by high-performance liquid chromatography (HPLC) are described. A urine sample from a patient with obstructive jaundice was passed through a Sep-Pak C18 cartridge and was separated into groups by ion-exchange chromatography on a lipophilic gel, piperidinohydroxypropyl Sephadex LH-20, providing the glucuronide fraction. Subsequent resolution into individual 3-glucuronides was attained by HPLC on muBondapak C18 and Shodex ODS Pak F-411 columns. The 3-glucuronides of cholate, deoxycholate, chenodeoxycholate, glycocholate, glycochenodeoxycholate and taurochenodeoxycholate were identified on the basis of their behaviour in HPLC using mobile phases of different pH. The enzymatic hydrolysis of these glucuronides and derivatization of deconjugated bile acids with 1-anthroyl nitrile followed by chromatographic separation on a Cosmosil 5C18 column with fluorescence detection were carried out for unequivocal characterization. The ratio of unconjugated, glyco- and tauro-conjugated bile acid 3-glucuronides excreted in urine was found to be ca. 2:3:1.

Bile Acids and Salts↗
PubMed1985

Studies on steroids. CCXVI. Separation of bile acid 3-glucuronides by high-performance liquid chromatography.

The separation of 3-glucuronides of cholate, chenodeoxycholate, deoxycholate, ursodeoxycholate and lithocholate, and their glyco- and tauro-conjugates, has been carried out by high-performance liquid chromatography on a reversed-phase column. The chromatographic behaviour of bile acid 3-glucuronides was dependent on the type of conjugation. An effect of the pH of the mobile phase on the capacity ratio was observed at higher pH for chenodeoxycholate 3-glucuronide, probably owing to steric interaction of the 7 alpha-hydroxy group with the carboxy group in the glucuronyl moiety. Conversion of the alpha-hydroxy function on the steroid nucleus into an oxo group resulted in a 50% decrease in the capacity ratio. Bile acid 3-glucuronides were efficiently separated on Shodex ODS Pak F-411 using three kinds of ammonium phosphate buffer-acetonitrile systems.

Bile Acids and Salts↗
PubMed1985

High performance liquid chromatographic separation of stereoisomeric bile acids as their UV-sensitive esters.

High performance liquid chromatographic separation of a series of mono-, di- and trihydroxylated 5 beta-cholanic acids, which differ only in position and configuration of hydroxyl groups at positions C-3, C-7 and/or C-12, is reported. The C-24 free acids were derivatized to four different classes of UV-sensitive esters, i.e., p-bromophenacyl (BP), m-methoxyphenacyl (MP), 4-nitrophthalimidemethyl (NPM) and 9-anthrylmethyl (AM) esters, and chromatographed on two variants of C18 reversed-phase columns (Nova-Pak C18 and Zorbax ODS) with methanol-water systems as mobile phase. Separation efficiency and elution order of some isomeric pairs were influenced by both the structure of the C-24 ester groups and the nature of the columns used. Excellent chromatographic properties were found for those derivatives, particularly for the NPM esters.

Bile Acids and Salts↗
PubMed1985

Alterations of serum bile acid profile in breast-fed infants with prolonged jaundice.

Serum bile acid conjugates in breast-fed infants with prolonged jaundice were analyzed by a newly developed procedure using high-performance liquid chromatography with fluorescence labeling. Major bile acids were cholate and chenodeoxycholate conjugates. Some of the breast-fed jaundiced infants had high levels of serum bile acid conjugates (greater than 25 mumol/L), but the mean levels of individual bile acid conjugates found in jaundiced breastfed infants were not significantly different from those in breast-fed infants without jaundice. The glycine- to taurine-conjugated bile acid ratio in breast-fed jaundiced infants was significantly lower than in breast-fed nonjaundiced infants or bottle-fed nonjaundiced infants. In breast-fed infants, the portion of taurine-conjugated bile acids increased in proportion to serum bilirubin levels. These findings suggest that alteration in conjugated bile acid patterns of breast milk jaundice is related to an increased enterohepatic circulation of bile acids as well as bilirubin in infants fed on breast milk that contains high amounts of taurine.

Bile Acids and Salts↗
PubMed1985

Structure-activity relationship of bufotoxins and related compounds for the inhibition of Na+, K+ -adenosine triphosphatase.

Forty kinds of bufotoxins and related compounds were tested for inhibition of Na+, K+ -adenosine triphosphatase from guinea pig heart, and the structure-activity relationship has been discussed. The inhibitory activities of bufotoxins were dependent upon the dicarboxylic acid and amino acid components. The compounds having both the arginine and suberic acid moieties showed the higher inhibitory activities. The sulfates and glucuronides of cardiac steroids exhibited much less potency than the parent genins. The mode of inhibition was determined by means of the Dixon and Lineweaver-Burk plots.

Animals↗
PubMed1985

A high-performance liquid chromatographic method for the assay of Na+, K+-adenosine triphosphatase inhibition.

A new method for the assay of Na+, K+-adenosine triphosphatase (Na+, K+-ATPase) inhibition has been devised involving the determination of enzymatically produced adenosine diphosphate (ADP) and unchanged adenosine triphosphate (ATP) by high-performance liquid chromatography (HPLC). The substrate, ATP, was incubated with the enzyme preparation in the presence of an inhibitor. The incubation mixture was filtered through a membrane filter, and ADP and ATP in the filtrate were separated by (HPLC). The inhibitory effect of a cardiac steroid on the enzymic reaction was estimated by measuring the peak area ratio of ADP to ADP plus ATP on the chromatogram. The proposed assay method has proved to be satisfactory with respects to simplicity, sensitivity, and reproducibility.

Adenosine Diphosphate↗
PubMed1984

Studies on steroids. CC. Determination of 17-ketosteroid sulphates in serum by high-performance liquid chromatography with electrochemical detection using pre-column derivatization.

A new sensitive method is described for the determination of 17-ketosteroid sulphates, particularly dehydroepiandrosterone sulphate, in human serum by high-performance liquid chromatography with electrochemical detection. The 17-ketosteroid sulphates in serum were extracted with acetonitrile and derivatized with p- nitrophenylhydrazine in trichloroacetic acid--benzene solution. The p- nitrophenylhydrazones were separated by high-performance liquid chromatography on a mu Bondapak C18 column using methanol--0.5% ammonium dihydrogen phosphate (8:3) as a mobile phase. The proposed method proved to be applicable to the quantitation of 17-ketosteroid sulphates with satisfactory sensitivity and reliability, providing a quantitation limit of 80 ng/ml and coefficient of variation of 4%. A good correlation was observed between the values obtained by the present method and radioimmunoassay for dehydroepiandrosterone sulphate in serum.

Adult↗
PubMed1984

Determination of a new antihypertensive agent (2R,4R)-2-(2-hydroxyphenyl)-3-(3-mercaptopropionyl)-4- thiazolidinecarboxylic acid in blood by high-performance liquid chromatography with electrochemical detection.

A sensitive method has been developed for the determination of a new antihypertensive agent, (2R,4R)-2-(2-hydroxyphenyl)-3-(3-mercaptopropionyl)-4-thiazolidinecar boxylic acid (I), in human blood. Because the drug is unstable in biological fluids, it was immediately derivatized by treating the freshly drawn blood specimens with N-(4-anilinophenyl)maleimide. The adduct was separated and determined by high-performance liquid chromatography with electrochemical detection on a reverse-phase column. The assay method was satisfactory with respect to the sensitivity and precision, providing a quantitation limit of 2 ng/ml and coefficient of variation of 3%. Preliminary pharmacokinetic data were obtained by orally administering I to two patients with essential hypertension.

3-Mercaptopropionic Acid↗
PubMed1984

Preparation of specific antisera to estrone-3-glucuronide and estriol-3-glucuronide.

The preparation and antigenic properties of estrone-3-glucuronide- and estriol-3-glucuronide-bovine serum albumin conjugates in which the hapten is linked to the carrier protein through an (O-carboxymethyl)oxime bridge at the C-6 position on the steroid nucleus, have been described. Antibodies raised against the two immunogens in the rabbit possessed high specificity to estrone-3-glucuronide and estriol-3-glucuronide, respectively, exhibiting little cross-reactivities with other estrogen conjugates and no cross-reactions with related steroids except for free estrogens, their 3-methyl ethers and 3-sulfates. The cross-reactive antibodies were eliminated by partial immunoadsorption on affinity chromatographic media using the estrone-3-methyl ether 17-(O-carboxymethyl)oxime- and estriol-3-methyl ether 16 (or 17)-hemisuccinate-aminohexyl Sepharose conjugates, respectively. The purified antisera exhibited no cross-reactivities with free estrogens and ring A conjugates of estrone and estriol.

Animals↗
PubMed1984

In vitro metabolic conjugation of catechol estrogens.

In vitro metabolic conjugation of the catechol estrogens, 2-hydroxyestrone and 4-hydroxyestrone, has been investigated by means of HPLC with electrochemical detection. Sulfation of 2-hydroxyestrone and 4-hydroxyestrone with the rat liver 105 000 g supernatant fortified with 3'-phosphoadenosine-5'-phosphosulfate provided the 2- and 4-monosulfates, respectively. Glucuronidation of the two catechols with the rat and human liver 1500 g supernatant in the presence of uridine-5'- phosphoglucuronic acid gave the 2- and 4-glucuronides, respectively. In contrast, incubation with the guinea pig liver 1500 g supernatant yielded both isomeric monoglucuronides . When 2'-hydroxyestrone was incubated with rat liver 1500 g supernatant and S-adenosyl-L-methionine, the 2- and 3-monomethyl ethers were formed in an equal amount, while 4-hydroxyestrone was transformed into the 4-methyl ether in 12 times greater yield than the 3-methyl ether. The participation of sulfation and glucuronidation in the formation of guaiacol estrogens is discussed.

Animals↗
PubMed1984

Preparation of specific antiserum to estriol 3-sulfate 16-glucuronide.

The preparation and antigenic properties of estriol 3-sulfate 16-glucuronide-bovine serum albumin (BSA) conjugate in which the hapten is linked to the carrier through an (O-carboxymethyl)oxime bridge at the C-6 position on the steroid nucleus, have been described. Coupling of 6-oxoestriol 3-sulfate 16-glucuronide acetate-methyl ester 6-(O-carboxymethyl)oxime with BSA by the activated ester method followed by removal of the protecting groups with alkali provided the desired conjugate. The antisera raised against the conjugate in rabbits were highly specific to the double conjugate, estriol 3-sulfate 16-glucuronide, discriminating from ring A or D monoconjugated and unconjugated estrogens. The specificity of antisera elicited has been discussed on the basis of stereochemistry of the hapten-[C-6]-BSA conjugate.

Cross Reactions↗