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Biomedical subjects

H Okuda

Publications and source records attributed to H Okuda.

At least 397 records · Page 22Linked to original sources
PubMed1984

[Subacute toxicity of an amine-curing agent for epoxy resin].

Amine-curing agent for epoxy resin, bis(4-amino-3-methylcyclohexyl)methane, has been suspected of inducing toxic symptoms in man which resemble collagen disease such as scleroderma or polymyositis. We studied subacute toxicity of this agent by repeated oral administrations to rats. The agent was administered 25, 37.5, 50, 75 or 100 mg/kg per one dose, 8 times in 10 days or 17 times in 4 weeks or 20-22 times in 4 weeks. When administration had been completed, clinical biochemical tests and histopathological examinations were carried out. Animals of high dosage group showed suppression of body weight increase and loss of muscular strength of limbs in the administration period. By clinical biochemical tests, elevation of blood components from muscle (CPK, GOT, creatine) was noticed. Also, increase of monoamine oxidase and decrease of alkaline phosphatase were revealed. By histological examinations, skeletal muscle and choroid plexus of brain showed noticeable changes. In muscles of high dosage group, atrophy, degeneration and regeneration of muscle fibers were observed and an increase of fibroblasts was also seen. In choroid plexus, vacuolar changes in epithelial cells were observed, being clearly dose-dependent. No particular change was recognized in skin. Though scleroderma-like change was not observed in the skin histologically, our results suggest that this amine-curing agent was greatly associated with muscle symptoms in the workers who handled epoxy resin and that it was one of causative agents which induced toxic symptoms like those of collagen disease.

Animals↗
PubMed1984

Effects of mazindol on lipid metabolism of human adipose tissue in vitro.

The interaction of mazindol with catecholamine in regulating peripheral lipid metabolism was studied in vitro. Noradrenaline-induced and adrenaline-induced glycerol release was augmented by addition of 50 ng mazindol. On the other hand, isoproterenol-induced glycerol release was suppressed by addition of 50 ng mazindol. Basal and dopamine-induced glycerol release was not altered by addition of 50 ng mazindol. These results suggest that mazindol may interact with alpha 2-adrenergic receptors in adipose tissue.

Adipose Tissue↗
PubMed1984

[Functional saving in the treatment of cervical cancer].

The radicality of Okabayashi's radical hysterectomy for treatment of cervical cancer has been well-known. However, its radicality also brought up the disturbance of fertility, endocrine and sexual function as well as the dysfunction of micturition and defecation. As early cervical cancer cases have increased yearly, and social rehabilitation became more necessary nowadays, functional saving is important and must be considered as the responsibility of the oncologists. This report denotes the preservation of ovarian function, sexual rehabilitation as well as the fertility in the treatment of cervical cancer.

Coitus↗
PubMed1983

Bilirubin diglucuronide formation by rat liver microsomes: demonstration by affinity and thin layer chromatography of bile pigment tetrapyrroles.

The conjugates formed in vitro by bilirubin UDP-glucuronyl transferase were studied by examining reaction products as intact tetrapyrroles, rather than as dipyrrolic azoderivatives. Bile pigments were extracted from conventional microsomal enzyme reaction mixtures by affinity chromatography over albumin-agarose, eluted with 50% ethanol, and separated by a silica gel thin layer chromatographic system. In the presence of UDPGA, native and activated microsomal preparations all formed both bilirubin mono- and diglucuronides from unconjugated bilirubin, and bilirubin diglucuronide from bilirubin monoglucuronide. No significant non-enzymatic conversion of mono- to diglucuronide occurred without UDPGA, or in the presence of denatured enzyme. Hence, bilirubin diglucuronide is a major product of bilirubin-UDP-glucuronyl transferase.

Animals↗
PubMed1983

Carboxylesterases in rat and human sera and their relationship of serum aryl acylamidases and cholinesterases.

The three enzyme activities, carboxylesterase, aryl acylamidase and cholinesterase activities, have been found in rat and human sera. Rat serum carboxylesterase associated with serum aryl acylamidase activity, but not with serum cholinesterase activity, was purified by ammonium sulfate precipitation, followed by successive chromatographies on DEAE-cellulose, blue Sepharose and QAE-Sephadex, and then electrophoresis. Evidence for the identity of the two enzymes, carboxylesterase and aryl acylamidase, was their co-elution profiles and co-purification in the different steps, including electrophoresis, with constant ratios of specific activities and percentage recoveries. Human serum carboxylesterase associated with serum cholinesterase, purified earlier, was compared with the rat serum esterase. Human serum carboxylesterase and aryl acylamidase activities were inhibited by serotonin and neostigmine, whereas rat serum carboxylesterase and aryl acylamidase activities were not affected by these compounds. Tyramine activated human but not rat aryl acylamidase. Rat and human serum esterase activities were both strongly inhibited by the diisopropylfluorophosphate. Both esterases catalyzed the hydrolysis of short-chain triacylglycerols, such as tributyrin, and medium-chain monoacylglycerols, such as monocaprin, but not the hydrolysis of long-chain triacylglycerols.

Amidohydrolases↗
PubMed1983

A sensitive spectrophotometric assay for guanase activity.

A highly sensitive and accurate spectrophotometric method was developed for determination of guanase activity with guanine as substrate. The assay is based on the oxidative coupling of 3-methyl-2-benzothiazolinone hydrazone and N,N-diethylaniline. Xanthine formed from guanine by guanase is oxidized to uric acid and hydrogen peroxide by xanthine oxidase, and the hydrogen peroxide produced is determined by an oxidative-coupling reaction with 3-methyl-2-benzothiazolinone hydrazone and N,N-diethylaniline mediated by peroxidase. Formation of the indamine dye is greatly affected by the superoxide radical ion (O2-) and pH value. These problems can be overcome by separating the two reactions of hydrogen peroxide formation and color production and carrying out that color-producing reaction at pH 3.0. This method is very sensitive and accurate because the indamine dye has a very high molar extinction coefficient of 29,800. It can be used with various kinds of automatic analyzers such as a Hitachi, Olympus, or Technicon analyzer. Comparative studies showed that this method is more sensitive and reproducible than other methods. Furthermore, guanase activities determined by this method correlated well with those determined by the improved Ellis-Goldberg method. This method should be useful for measurement of guanase activity in banked blood for preventing transfusion hepatitis and could be valuable as a liver function test.

Aminohydrolases↗
PubMed1983

Lack of dominant lethal effects in male CD-1 mice after short-term and long-term exposures to vinyl chloride monomer.

Dominant lethal studies were conducted with vinyl chloride monomer (VCM) in male CD-1 mice, using short-term (10 000 ppm, 4 h/day, for 5 days) and long-term (5000 ppm, 4 h/day, 5 day/week, for 10 weeks) exposures. There was no evidence of dominant lethal effects due to VCM in either case. Semen examination of male mice after long-term exposure failed to reveal any alteration in sperm motility and shape. Sporadic appearance of giant cells was observed in the testes of males exposed to VCM, but was not considered to affect spermatogenesis.

Animals↗
PubMed1983

Role of endogenous lipid droplets of fat cells in epinephrine-induced lipolysis.

Endogenous lipid droplets were prepared by subjecting fat cells to hypotonic shock and to Triton X-100 treatment. The structure of the endogenous lipid droplet fraction was examined by scanning and transmission electron microscopies. Neither intact fat cells nor disrupted cell membranes were detectable in the endogenous lipid droplet fraction. With this endogenous substrate, epinephrine elicited lipolysis with either hormone-sensitive lipase or lipoprotein lipase, but no cyclic AMP-protein kinase mediated stimulation of lipolysis was observed. On the other hand, epinephrine did not stimulate lipolysis when triolein emulsified with arabic gum was used as substrate. With the latter exogenous substrate, however, cyclic AMP-protein kinase was found to stimulate lipolysis with hormone-sensitive lipase as enzyme. These results agree with the proposal of Wise and Jungas that the epinephrine-stimulated increase of hydrolysis of endogenous fat is not mediated through cyclic AMP-protein kinase. A possible mechanism of hydrolysis of endogenous fat by induction of lipolysis by epinephrine in fat cells is discussed.

Adipose Tissue↗
PubMed1983

Human liver carboxylesterase. Properties and comparison with human serum carboxylesterase.

Carboxylesterase was obtained from human liver in an electrophoretically homogeneous form. The monomeric molecular weight of the enzyme was 60,000 and the enzyme associated to form trimers. Purified human liver carboxylesterase was compared with human serum carboxylesterase, purified earlier. Serum carboxylesterase hydrolyzed a typical cholinesterase substrate and aryl acylamide, whereas liver carboxylesterase did not hydrolyze these compounds. Both carboxylesterases catalyzed the hydrolysis of short-chain triacylglycerols, such as tributyrin, and medium-chain monoacylglycerols, such as monocaprin, but not the hydrolysis of long-chain triacylglycerols. Serum carboxylesterase activity was inhibited by p-trimethylammoniumanilinium dichloride and neostigmine, whereas liver carboxylesterase activity was not affected by these compounds. Liver and serum carboxylesterase activities were both strongly inhibited by phenylmethylsulfonyl fluoride.

Carboxylic Ester Hydrolases↗
PubMed1983

Fatty acid synthesis in adipose tissues of physically trained rats in vivo.

The effect of physical training on fatty acid synthesis in vivo was studied. After the rats had free access to a running wheel for 50 days, the rate of fatty acid synthesis estimated using 3H2O in adipose tissues of trained rats was about three times higher than that of sedentary rats in both the light and dark period. The rate of fatty acid synthesis in the liver but not in the brown adipose tissue was also slightly enhanced by physical training. The number of adipocytes was not affected, but the size of adipocytes was reduced by physical training. In trained rats, the rate of fatty acid synthesis in adipocytes whose diameter was similar to that of sedentary rats was about 10 times higher than that of sedentary rats. Within adipose tissue, the rate of fatty acid synthesis correlated positively to the diameter of adipocytes both in the sedentary and trained rats. These findings mean that the adaptive increase in fatty acid synthesis seen in adipocytes of trained rats is not secondary to the reduction in size of adipocytes.

Adipose Tissue↗