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Biomedical subjects

S Tamura

Publications and source records attributed to S Tamura.

At least 703 records · Page 39Linked to original sources
PubMed1985

Hypercholinesterasemia with isoenzymic alteration in a family.

A family with hypercholinesterasemia with isoenzymic alteration is reported. The propositus, a 55-year-old woman, was admitted to our hospital because of diabetes mellitus. Because her cholinesterase activity (delta pH 3.2) was supranormal, with no other abnormal liver-function test result throughout the hospitalization period, and was independent of her disease state, we investigated whether this condition might be familial. We studied six of her 17 family members in three generations. All six had above-normal serum cholinesterase activity. Gradient gel electrophoresis on polyacrylamide showed that the normal control individuals had seven isoenzymes, but all the family members with hypercholinesterasemia had two additional isoenzymes. The enzymic properties of the affected members were similar to those of the normal individuals. Hypercholinesterasemia in this family seems to be the result of an increased number of enzyme molecules, but how this isoenzymic alteration emerged remains obscure.

Alcohols↗
PubMed1984

A novel mechanism for the insulin-like effect of vanadate on glycogen synthase in rat adipocytes.

Vanadate activated rat adipocyte glycogen synthase similarly to insulin in a dose- and time-dependent manner. No additional effect was observed when insulin and vanadate were added together. Vanadate also partially counteracted the effect of epinephrine to activate rat adipocyte glycogen phosphorylase similarly to insulin. Inhibition of Na+K+ATPase or stimulation of hydrogen peroxide generation were shown not to be the mechanisms of the insulin-like action of vanadate on glycogen synthase. Vanadate stimulated the phosphorylation of the 95,000-dalton subunit of the insulin receptor on tyrosine residues both in intact adipocytes and in a solubilized insulin receptor fraction. Vanadate also stimulated the phosphorylation of the 95,000-dalton subunit of a highly purified insulin receptor from human placenta. Neither the insulin receptor fraction from rat adipocyte nor the highly purified insulin receptor from human placenta contained any detectable phosphotyrosine phosphatase activity. Potassium fluoride had no stimulatory effect on the phosphorylation of the insulin receptor. Vanadate caused a 10-fold decrease in the Km for ATP, for tyrosine kinase, and enhanced the phosphorylation of histone H2B. These results demonstrate that vanadate enhances the phosphorylation of the insulin receptor by stimulating the kinase reaction in a similar but not identical manner to insulin.

Adipose Tissue↗
PubMed1984

Mechanisms subserving insulin action in the gonad: evidence that insulin induces specific phosphorylation of its immunoprecipitable receptor on ovarian cells.

To test the capacity of insulin to work through a classical insulin-receptor pathway in the ovary, cultured swine granulosa cells were treated with insulin and/or increasing concentrations of insulin-receptor antiserum. Insulin-receptor antiserum but not control serum significantly (greater than 85%) attenuated insulin's stimulation of progesterone biosynthesis. Moreover, in broken-cell preparations, insulin but not desoctapeptide insulin or somatomedins induced specific phosphorylation of the 95,000-dalton, immunoprecipitated beta subunit of the insulin receptor on ovarian cells. These observations provide the first evidence for discrete biochemical actions of insulin at the level of the cell-membrane receptor for insulin in gonadal cells.

Animals↗
PubMed1984

Selective inhibition of the insulin-stimulated phosphorylation of the 95,000 dalton subunit of the insulin receptor by TAME or BAEE.

Added N alpha-p-tosyl-l-arginine methyl ester or N alpha-benzoyl-l-arginine ethyl ester inhibited the stimulation by insulin of phosphorylation of the 95,000 dalton subunit of the insulin receptor both in a partially purified insulin receptor fraction from rat adipocytes and in a highly purified insulin receptor preparation from human placenta. N-alpha-p-tosyl-l-lysine chloromethyl ketone, N alpha-p-tosyl-l-lysine methyl ester, or N-acetyl-l-phenylalanine ethyl ester were much less potent, while N-benzoyl-1-alanine methyl ester was without effect. Inhibition of the phosphorylation by the arginine analogues did not require preincubation of the insulin receptor with inhibitors in the presence of insulin prior to phosphorylation. Inhibition by N alpha-p-tosyl-l-arginine methyl ester was decreased by preincubation of the receptor fraction with cold ATP and MnCl2. These results suggest that N alpha-p-tosyl-l-arginine methyl ester inhibits an initial ATP and Mn2+ dependent reaction in insulin-stimulated phosphorylation process.

Adipose Tissue↗
PubMed1984

Selective effects of Lipiodolized antitumor agents.

Lipiodol Ultra-Fluid (Lipiodol) remains selectively in the tumor for an extended time when applied through arteries feeding the tumor. Although lipophilic antitumor drugs are selective when combined with Lipiodol, wide application of common hydrophilic agents is limited, as these compounds are insoluble in oil. We propose "Lipiodolization" of water-soluble agents using as an intermediate Urografin, a water-soluble contrast medium. Thirteen patients with primary hepatocellular carcinoma were treated with this Lipiodol-Urografin system containing antitumor agents. Marked decrease in serum alpha-fetoprotein (AFP) levels, decrease in tumor size in the hepatic imaging, and histologic studies of the resected specimen revealed this mode of therapy to be effective in 10 of 13 patients (77%) with hepatocellular carcinoma. Lipiodolization of antitumor agents is a new approach to selective cancer chemotherapy.

Adult↗
PubMed1984

Effect of high doses of synthetic estrogen on lipid metabolism in castrated male rats.

The mechanism by which high doses of estrogen influences lipid metabolism was studied with a microtubular blocking agent. Castrated male rats received oral injection daily for 14 days of 3 mg hexestrol in olive oil, or oil alone as controls. About half of the animals in each group were injected intraperitoneally with 4 mg/100 g body weight colchicine 3 hr before they were killed. Hexestrol treatment caused an accumulation of esterified cholesterol in the liver while it decreased those in serum. Triglyceride concentrations slightly decreased in the liver but were unaffected in serum. On polyacrylamide-gel disc electrophoresis, the peaks of high density lipoproteins (HDL) and low density lipoproteins (LDL) were decreased remarkably. Electron microscopic examination of hepatocytes revealed electron-lucent lipid droplets in the cytoplasm. After a colchicine treatment of the control animals, concentrations of esterified cholesterol and triglycerides markedly increased in the liver, while those in serum decreased. Electron microscopic examination of hepatocytes revealed numerous secretory vesicles filled with nascent VLDL. In hexestrol-treated animals, the colchicine treatment was associated with marked decreases in serum-esterified cholesterol and triglyceride as seen in the controls. However, there were no further increases of esterified cholesterol in the liver, and the increase of triglycerides was slight. Electron microscopic examination showed less secretory droplets than in the controls. These data suggest that very low density lipoproteins (VLDL) synthesis in the liver of hexestrol treated rats was inhibited. An accumulation of esterified cholesterol with a marked decrease in serum could not be accounted for by the inhibition of lipoproteins secretion, but rather by their enhanced entry into the liver.

Animals↗
PubMed1984

Isolation and some characterization of the prothoracicotropic hormone from Bombyx mori.

The prothoracicotropic hormone (PTTH) was isolated from adult heads of Bombyx mori. Fifty micrograms of pure PTTH was obtained from 648,000 heads through a 15-step purification procedure with a 2 X 10(6)-fold purification and an 8% recovery. Chemical analyses of this PTTH have shown that it is a single-chain peptide consisting of 40-43 amino acid residues (MW, 4330-4740), the N-terminus of which is glycine. As little as 0.1 ng of PTTH elicited adult development in a debrained pupa of Samia cynthia ricini. Five picograms of PTTH directly stimulated the prothoracic glands in vitro so as to enhance ecdysone release. The hemolymph ecdysteroids of brainless Samia pupae that were developed by PTTH injection increased with essentially the same pattern as in developing normal pupae.

Amino Acid Sequence↗
PubMed1984

Posttranscatheter embolization computed tomography in hepatocellular carcinoma. Evaluation of embolization effects.

The postcontrast CT scans and angiography of 26 lesions in 23 patients with hepatomas who underwent transcatheter arterial embolization therapy were reviewed. Newly developed low density and high density areas and gas were noted on CT scans of the tumors after embolization in 100, 8 and 58% of the lesions, respectively. The CT findings of residual tumors correlated well with those of follow-up angiography. When discrete smooth round low density zones were observed on CT, there was no residual neovascularity on follow-up arteriography. When there were nodular or thick septum-like structures in low density lesions, arteriography revealed residual tumor vascularity in the lesions. CT proved useful not only in evaluating the effects of embolization, but also in providing important information about residual tumors.

Aged↗
PubMed1984

Solubilization of intraglomerular deposits of serum proteins by fresh human sera or gamma-globulin in patients with diabetic nephropathy.

The solubilization of renal deposits of IgG and other serum proteins by fresh human sera or human gamma-globulin was studied in patients with diabetic nephropathy. Renal biopsy specimens were from 10 patients with diabetic nephropathy. These specimens were incubated with fresh sera obtained from the same patients and healthy adults or human gamma-globulin at 37 degrees C for 1 hr in plastic test tubes. The sections were stained with FITC-labeled heavy chain specific anti-human IgG, alpha 1-antitrypsin, haptoglobin and beta-lipoprotein antisera, and then examined with a fluorescent microscope. It was demonstrated that fresh human sera or gamma-globulin significantly solubilized glomerular deposits of IgG and other serum proteins in patients with diabetic nephropathy. It was postulated that solubilization of protein deposits in glomeruli requires the same substances detected in vitro in the kidney tissues from patients with diabetic nephropathy.

Adult↗
PubMed1984

Cytosolic protein phosphatases of rat ascites hepatoma AH-13 as compared with those of rat liver: isolation and characterization of a novel protein phosphatase.

To investigate the alterations of phosphoseryl/phosphothreonyl-protein phosphatases in neoplastic tissues, the cytosols of rat liver and AH-13, a strain of rat ascites hepatoma, were chromatographed on DEAE-cellulose and the fractions obtained were assayed for protein phosphatase with glycogen synthase D and phosphorylase alpha as phosphoprotein substrates. While the glycogen synthase phosphatase and phosphorylase phosphatase activities of liver cytosol were largely due to phosphatases IA and II, respectively, as previously reported, these phosphatases were absent or present in only small amounts in AH-13 cytosol, whose glycogen synthase phosphatase and phosphorylase phosphatase activities were due almost wholly to a novel protein phosphatase that appeared to be absent in liver. This phosphatase, termed phosphatase H, was purified further by aminohexyl-Sepharose-4B and Sephadex G-200 chromatography without altering its glycogen synthase D/phosphorylase alpha activity ratio. Purified phosphatase H required Mg2+ or Mn2+ for activity and had a molecular weight of about 330,000. It displayed a substrate specificity broader than that of either phosphatase IA or II.

Animals↗
PubMed1984

[A specific and quantitative determination of rat beta-endorphin. Combination of HPLC and RIA].

A specific and quantitative method for the determination of rat beta-endorphin by the combination of HPLC and RIA was developed. Rabbit antiserum against camel beta-endorphin (c beta-E) was raised and used for RIA at the final concentration of 1:10000. The quantitative range estimated from the displacement curve was 0.1-2.0 ng. Cross-reactivities with Met-Enk, Leu-Enk, alpha-MSH, alpha-endorphin, ACTH and human beta-E were less than 0.1, less than 0.1, less than 0.1, less than 0.1, 2 and 100%, respectively. These peptides were separated from each other by reversed phase HPLC with UV254 nm detection, and the minimum detectable dose of c beta-E was found to be 1 microgram. beta-E-like immunoreactivity (beta-ELIR) in the HPLC effluent was determined by RIA. The HPLC-RIA chromatogram of authentic c beta-E exhibited a single peak which coincided with the peak of c beta-E detected by UV, and 80% of the injected c beta-E (1-100 ng) was detected in the c beta-E fraction. The HPLC-RIA chromatogram of rat pituitary, hypothalamus, cerebrospinal fluid and plasma revealed the presence of 1-3 peaks, one of which was observed at the position of c beta-E. The HPLC elution of rat pituitary resolved the material into two peaks of biological activity, one of which coincided with the peak of beta-ELIR at the position of c beta-E. The HPLC-RIA chromatogram of the c beta-E fraction from pituitary obtained by gel-chromatography exhibited three peaks, one of which coincided with c beta-E. These results suggest that beta-ELIR in the c beta-E fraction of the HPLC elution may reflect rat beta-E accurately.

Animals↗