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Biomedical subjects

T Kuramoto

Publications and source records attributed to T Kuramoto.

At least 127 records · Page 7Linked to original sources
PubMed1984

Synthesis of homoursodeoxycholic acid and [11,12-3H]homoursodeoxycholic acid.

Homoursodeoxycholic acid and [11,12-3H]homoursodeoxycholic acid were synthesized from ursodeoxycholic acid and homocholic acid, respectively. Ursodeoxycholic acid (Ia) was converted to 3 alpha, 7 beta-diformoxy-5 beta-cholan-24-oic acid (Ib) using formic acid. Reaction of the diformoxy derivative (Ib) with thionyl chloride yielded the acid chloride (II) which was treated with diazomethane to produce 3 alpha, 7 beta-diformoxy-25-diazo-25-homo-5 beta-cholan-24-one (III). Homoursodeoxycholic acid (IV) was formed from the diazoketone (III) by means of the Wolff rearrangement of the Arndt-Eistert synthesis. N-Bromosuccinimide oxidation of homocholic acid (V), which was prepared from cholic acid by the same procedure described above, afforded 3 alpha, 12 alpha-dihydroxy-7-oxo-25-homo-5 beta-cholan-25-oic acid (VI). Reduction of the 7-ketohomodeoxycholic acid (VI) with sodium in 1-propanol gave 3 alpha, 7 beta, 12 alpha-trihydroxy-25-homo-5 beta-cholan-25-oic acid (VII). The methyl ester of 7-epihomocholic acid (VII) was partially acetylated to give methyl 3 alpha, 7 beta-diacetoxy-12 alpha-hydroxy-25-homo-5 beta-cholan-25-oate (VIII) using a mixture of acetic anhydride, pyridine and benzene. Dehydration of the diacetoxy derivative (VIII) with phosphorus oxychloride yielded methyl 3 alpha, 7 beta-diacetoxy-25-homo-5 beta-chol-11-en-25-oate (IX). Reduction of the unsaturated ester (IX) with tritium gas in the presence of platinum oxide catalyst followed by alkaline hydrolysis gave [11,12-3H]homoursodeoxycholic acid.

Chemical Phenomena↗
PubMed1984

Identification of bile alcohols in urine from healthy humans.

Bile alcohols present in urine from healthy adults were studied. Urine was extracted with octadecylsilane-bonded silica gel, and a neutral fraction and a glucuronide fraction were isolated by ion exchange chromatography on piperidinohydroxypropyl Sephadex LH-20. Following hydrolysis of the glucuronide fraction with beta-glucuronidase and purification by silica gel column chromatography, the bile alcohols were analyzed by a combined gas-liquid chromatography-mass spectrometry. By direct comparison with reference standards, the structures of four major bile alcohols were elucidated as follows: 27-nor-5 beta-cholestane-3 alpha,7 alpha,12 alpha,24,25- pentol ; 5 beta-cholestane-3 alpha,7 alpha,12 alpha,24, 25- pentol ; 5 beta-cholestane-3 alpha,7 alpha,12 alpha,25,26- pentol ; and 5 beta-cholestane-3 alpha,7 alpha,12 alpha,26,27- pentol . The daily excretion of these four bile alcohols in urine was 0.5-1.0 mumoles. After purification by silica gel column chromatography, the neutral fraction was analyzed by a combined gas-liquid chromatography-mass spectrometry. The major bile alcohol excreted in urine as the unconjugated form was 27-nor-5 beta-cholestane-3 alpha,7 alpha,12 alpha,24,25- pentol . The daily excretion of the unconjugated C26 pentol (0.02-0.05 mumoles) was far lower than that of the conjugated C26 pentol (0.34-0.86 mumoles).

Adult↗
PubMed1983

Effect of feeding cholesterol and sitosterol on hepatic steroid 12 alpha-hydroxylase activity in female hamsters.

The effects of dietary cholesterol and sitosterol on the activity of the hepatic steroid 12 alpha-hydroxylase, gallbladder bile acid composition, and serum and liver cholesterol concentrations were studied in female hamsters. The 12 alpha-hydroxylase activity was inhibited by 63% in cholesterol-fed animals and by 30% in sitosterol-fed animals. Cholesterol feeding increased percentages of chenodeoxycholic and lithocholic acids in gallbladder bile with reciprocal decrease of cholic acid, while sitosterol feeding had no significant effect on bile acid composition. Cholesterol feeding increased levels of serum and liver cholesterol, on the contrary, sitosterol decreased both concentrations. A positive correlation between the 12 alpha-hydroxylase activity and the ratio of cholic acid plus its metabolites to chenodeoxycholic acid plus its metabolite was also observed. These results support the proposal that steroid 12 alpha-hydroxylase is a major factor in determining the relative proportion of cholic acid and chenodeoxycholic acid synthesized in the liver and indicate that cholesterol feeding increased percentage of chenodeoxycholic acid by inhibiting the activity of steroid 12 alpha-hydroxylase.

Animals↗
PubMed1983

Sex differences in gallbladder bile acid composition and hepatic steroid 12 alpha-hydroxylase activity in hamsters.

The gallbladder bile acid composition and the activity of the hepatic steroid 12 alpha-hydroxylase were determined in male and female hamsters. Cholic acid, chenodeoxycholic acid, and deoxycholic acid were the major bile acids in both sexes; in addition, 7-ketodeoxycholic acid and lithocholic acid were present. A sex-linked difference in the ratio of cholic acid (plus its metabolites) to chenodeoxycholic acid (plus its metabolite) was observed. The ratio was 1.93 +/- 0.39 in males and 2.74 +/- 0.54 in females. Another sex-linked difference was found in the activity of the 12 alpha-hydroxylase. The extent of the 12 alpha-hydroxylation of 7 alpha-hydroxycholest-4-en-3-one to yield 7 alpha, 12 alpha-dihydroxycholest-4-en-3-one was about two times greater in the microsomal suspension obtained from the liver of female hamsters than in that of male hamsters. A positive correlation between the 12 alpha-hydroxylase activity and the ratio of cholic acid/chenodeoxycholic acid was also observed. These results strongly support the proposal that the activity of the 12 alpha-hydroxylase is the major factor in determining the relative proportion of cholic acid and chenodeoxycholic acid formed from cholesterol in the liver.

Animals↗
PubMed1983

Synthesis of four diastereoisomers at carbons 24 and 25 of 3 alpha,7 alpha,12 alpha,24-tetrahydroxy-5 beta-cholestan-26-oic acid, intermediates of bile acid biosynthesis.

The synthesis of four stereoisomers at C-24 and C-25 of 3 alpha,7 alpha,12 alpha,24-tetrahydroxy-5 beta-cholestan-26-oic acid is described. Pyridium chlorochromate oxidation of 3 alpha,7 alpha,12 alpha-triacetoxy-5 beta-cholan-24-ol (II) prepared from cholic acid (I) afforded 3 alpha,7 alpha,12 alpha-triacetoxy-5 beta-cholan-24-al (III) which was converted to a mixture of the four stereoisomers (IV-VII) by a Reformatsky reaction with ethyl DL-alpha-bromopropionate followed by alkaline hydrolysis. Separation of these isomers (IV-VII) was achieved by silica gel column chromatography, and subsequent reversed-phase partition column chromatography. The configurations at C-24 were elucidated by conversion of each isomer into (24R)- or (24S)-5 beta-cholestane-3 alpha,7 alpha,12 alpha,24-tetrol (XII or XI) by Kolbe electric coupling, the C-24 configurations of which were determined by modified Horeau's method and 13C-nuclear magnetic resonance spectroscopy. The stereochemistries at C-25 were deduced by comparison of IV-VII with the products of the hydroboration followed by oxidation with alkaline hydrogen peroxide of (24E)-3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholest-24-en-26-oic acid (XIII).

Bile Acids and Salts↗
PubMed1983

The minor bile acids of the toad, Bufo vulgaris formosus.

Bile from the toad, Bufo vulgaris formosus, was found to contain a number of minor bile acids along with two major bile acids, 3 alpha, 7 alpha, 12 alpha-trihydroxy-5 beta-cholest-22-ene-24-carboxylic acid and 3 alpha, 7 alpha, 12 alpha-trihydroxy-5 beta-cholest-23-en-26-oic acid. The following minor bile acids were identified by combined gas-liquid chromatography-mass spectrometry: cholic acid, allocholic acid, 3 alpha, 7 alpha, 12 alpha-trihydroxy-5 beta-cholestan-26-oic acid, 3 alpha, 7 alpha, 12 alpha-trihydroxy-5 alpha-cholestan-26-oic acid, 3 alpha, 7 alpha, 12 alpha-trihydroxy-5 alpha-cholest-22-ene-24-carboxylic acid, 3 alpha, 7 alpha, 12 alpha-trihydroxy-5 alpha-cholest-23-en-26-oic acid, varanic acid, and 3 alpha, 7 alpha, 12 alpha, 24-tetrahydroxy-24-methyl-5 beta-cholestan-26-oic acid. The fact that the toad bile contains not only cholic acid but also 3 alpha, 7 alpha, 12 alpha-trihydroxy- and 3 alpha, 7 alpha, 12 alpha,24-tetrahydroxy-5 beta-cholestan-26-oic acids, which have been recognized as biosynthetic intermediates of cholic acid in mammals, suggests that the toad is capable of synthesizing cholic acid by the same pathway as that for the biosynthesis of the C24 bile acid in mammals.

Animals↗
PubMed1981

The K+ liquid ion exchange electrode system: responses to drugs and neurotransmitters.

K+-sensitive liquid ion exchange electrode systems respond with a slow potential change to acetylcholine, choline, anticholinergic drugs, biogenic amines, and glutamic acid. The response threshold has been defined, and in most cases it is at extremely low concentrations (10(-7)-10(-5)M). The direction of the potential change varies, but in most instances it is additive to that produced by external K+. The K+ electrode system is further sensitive to decreasing pH, within a narrow and possibly physiological range of pH. These findings suggest that small measured changes in extracellular K+ are biased by the chemosensitivity of the liquid ion exchange electrode system to some compounds of physiological importance.

Acetylcholine↗
PubMed1981

Membrane properties of a human neuroblastoma II: Effects of differentiation.

The SK-N-SH cell line is a human neuroblastoma which when grown under standard culture conditions remains relatively undifferentiated. The undifferentiated SK-N-SH cells are relatively inexcitable: they show only partial active responses to injections of current pulses and lack the depolarizing component of the action potential generating mechanism [Kuramoto et al, 1977]. In this study we report on the membrane properties of two subclones of the SK-N-SH, the SK-N-SH-IN (referred to as IN) and the SK-N-SH-Sy5Y (referred to as 5Y) which exhibit extensive morphological differentiation when grown with 1mM dibutyryl cAMP. Fully differentiated IN and 5Y cells have higher resting membrane potentials, in the range of -50 to -80 mV, and higher input resistance and time constants than do the undifferentiated SK-N-SH parental cell line. After 1 week in culture the differentiated IN and 5Y cells exhibit spike potentials in response to injection of current to the cell body. The presence of the Na2+-dependent depolarization was verified directly by the use of tetrodotoxin (TTX) and indirectly in experiments where veratridine (0.1 mM) markedly enhanced the influx of 22Na+. Taken together, the data indicate that generation of action potentials in these human neuroblastoma cells is to a large extent a function of morphological differentiation.

Acetylcholine↗
PubMed1981

Metabolism of bile alcohols, 24-nor-5 beta-cholestane-3 alpha,7 alpha,12 alpha,24-tetrol and 3 alpha,7 alpha,12 alpha-trihydroxy-26,27-dinor-5 beta-cholestan-24-one, in rats.

24-Nor-5 beta-cholestane-3 alpha,7 alpha,12 alpha,25-tetrol and 3 alpha,7 alpha,12 alpha-trihydroxy-26,27-dinor-5 beta-cholestan-24-one were administered intraperitoneally to bile fistula rats, and the metabolites excreted in the bile were analyzed. No formation of bile acids from these bile alcohols was observed. 7 alpha,12 alpha,25-Trihydroxy-24-nor-5 beta-cholestane-3 alpha-O-(beta-D-glucopyranosid)uronic acid was identified as the only biliary metabolite of the 24-nor-5 beta-cholestanetetrol. The major metabolite of the trihydroxy-26,27-dinor-5 beta-cholestanone was 7 alpha,12 alpha-dihydroxy-24-oxo-26,27-dinor-5 beta-cholestane-3 alpha-O-(beta-D-glucopyranosid)uronic acid, and the minor metabolite was the glucurono conjugate of 26,27-dinor-5 beta-cholestane-3 alpha,7 alpha,12 alpha,24 beta-tetrol. The results indicated that in rat liver these C25- and C26-bile alcohols, in contrast to C27-bile alcohols, were not converted into bile acids, and that the glucuronide production became necessary for hepatic elimination of the accumulated bile alcohols.

Animals↗
PubMed1980

Effect of dietary taurine on bile acid metabolism in guinea pigs.

The effect of oral administration of taurine (200-300 mg daily) on the metabolism of bile acids was studied in male guinea pigs which have predominantly glycine conjugated bile acids. The results were summarized as follows: (a) oral administration of taurine for 10 days increased taurine-conjugated bile acids and the ratio of glycine- to taurine-conjugated bile acids (G:T ratio) shifted from 3.95 to 0.19; (b) in taurine fed guinea pigs, the half-life of chenodeoxycholic acid (CDC) was about 40% shorter than that in controls and the fractional turnover rate increased by 70%; (c) the synthetic rate (mg/day/500 g body weight) of bile acids increased from 4.28 to 7.27 by taurine feeding; (d) hepatic cholesterol 7 alpha-hydroxylase activity was increased 2.4-fold by taurine feeding; (e) the total pool size of bile acids did not change significantly but the amount of lithocholic acid in the caecum and large intestine increased by about 40%; (f) neither free cholesterol nor cholesterol ester levels in liver and serum changed significantly. Results of this study suggest that changing the G:T ratio in the bile acid conjugation pattern may influence the rate of hepatic bile acid synthesis.

Administration, Oral↗
PubMed1980

Bile acids and bile alcohols of bullfrog.

Gallbladder bile of the bullfrog, Rana cetesbeiana was found to contain a number of minor bile acids and bile alcohols in unconjugated forms. The following bile acids and bile alcohols were identified by combined gas-liquid chromatography-mass spectrometry: cholic acid, allocholic acid, 3 alpha,7 alpha,12 alpha-trihydroxy-5 alpha-cholestan-26-oic acid, 3 alpha,7 alpha,12 alpha-trihydroxy-24-methyl-5 beta-cholestan-26-oic acid, 3 alpha,7 alpha,12 alpha,24-tetrahydroxy-5 alpha-cholestan-26-oic acid, 3 alpha,7 alpha,12 alpha,24-tetrahydroxy-5 beta-cholestan-26-oic acid, 3 alpha,7 alpha,12 alpha,26-tetrahydroxy-5 alpha-cholestan-27-oic acid, 3 alpha,7 alpha,12 alpha,26-tetrahydroxy-5 beta-cholestan-27-oic acid, 3 alpha,7 alpha,12 alpha-trihydroxy-27-nor-5 alpha-cholestan-24-one, and 3 alpha,7 alpha,12 alpha-trihydroxy-27-nor-5 beta-cholestan-24-one. These minor constituents of the bile may represent intermediates in the biosynthetic pathway of bile acids and bile alcohols in the bullfrog.

Animals↗
PubMed1980

Bile salts of frogs: a new higher bile acid, 3 alpha, 7 alpha, 12 alpha, 26-tetrahydroxy-5 beta-cholestanoic acid from the bile Rana plancyi.

Bile salts of ten species of frogs of the family Ranidae were examined by means of thin-layer chromatography, gas-liquid chromatography, and gas-liquid chromatography-mass spectrometry. Their major bile alcohols were ranol, cyprinol, or bufol. Four species of frogs contained lesser amounts of higher bile acids, and in two species C24 bile acids were present. A higher bile acid that has not been previously described was detected in Rana plancyi. On the basis of the spectral data and the direct comparison with a synthetic sample, the chemical structure of the new bile acid was established to be 3 alpha, 7 alpha, 12 alpha, 26-tetrahydroxy-5 beta-cholestanoic acid.

Animals↗
PubMed1980

Occurrence of bile alcohols in the bile of a patient with cholestasis.

Considerable amounts (6.0 mumol/ml of bile) of bile alcohols were found in the bile of a patient with cholestasis due to gallstones in a common bile duct. Acid hydrolysis of the bile salts followed by chromatographic separation yielded three bile alcohols, which were identified as 26,27-dinor-5 beta-cholestane-3 alpha,7 alpha,12 alpha,24,25-pentol, 24-methyl-26,-27-dinor-5 beta-cholestane-3 alpha,7 alpha, 24-tetrol, and 3 alpha,7 alpha, 12 alpha-trihydroxy-26,27-dinor-5 beta-cholestan-24-one by comparison with synthetic reference standards.

Aged↗
PubMed1980

Occurrence of bile alcohol glucuronides in bile of patients with cerebrotendinous xanthomatosis.

Using thin-layer chromatography, bile alcohol glucuronides were found with taurine- and glycine-conjugated bile acids in the bile of four patients with cerebrotendinous xanthomatosis. The concentration of the bile alcohol glucuronides was 1.7-5.2 times higher than that of the conjugated bile acids. Detectable amounts of unconjugated bile alcohols were not found in the bile of these patients. The bile alcohol glucuronides were isolated from the bile of one of the patients by means of preparative thin-layer chromatography. Treatment with beta-glucuronidase of the bile alcohol glucuronides liberated glucuronic acid and a mixture of bile alcohols. More than 90% of the liberated bile alcohols was 5 beta-cholestane-3 alpha, 7 alpha, 25-tetrol, and lesser amounts of 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha, 23-tetrol, 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha, 24-tetrol, 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha, 23, 25-pentol, and 5 beta-cholestane-3 alpha,-7 alpha, 12 alpha, 24 alpha, 25-pentol were also obtained. The bile alcohol glucuronides were not oxidized by the treatment with 3 alpha-hydroxysteroid dehydrogenase, indicating that the glucuronide moiety was at 3 alpha-hydroxyl position of the bile alcohols. Comparison of the mass spectra of the acetylated and methylated derivatives of the natural glucuronides and the synthetic 7 alpha, 12 alpha, 25-triacetoxy-5 beta-cholestan-3 alpha-O-(methyl 2,3,4-tri-O-acetyl-beta-D-glucopyranosyluronate) also indicated that the bile alcohol glucuronides consisted of mainly 5 beta - cholestane - 3 alpha, 7 alpha, 12 alpha, 25 - tetrol - glucuronide.

Adult↗