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Biomedical subjects

Y Hino

Publications and source records attributed to Y Hino.

At least 91 records · Page 5Linked to original sources
PubMed1985

Glucosidase II, a glycoprotein of the endoplasmic reticulum membrane. Proteolytic cleavage into enzymatically active fragments.

Glucosidase II removes the inner two alpha-linked glucose residues from freshly transferred Asn-linked oligosaccharide chains in the endoplasmic reticulum. This enzyme, whose activity could be measured by the hydrolysis of an artificial substrate (p-nitrophenyl alpha-D-glucopyranoside), was purified 240-fold from a rat liver microsome fraction by DEAE-cellulose, concanavalin A-Sepharose 4B, and hydroxylapatite chromatography. The apparent molecular weight of the active polypeptide was 123 000 as estimated by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. Glucosidase II has at least one high-mannose oligosaccharide chain that can be cleaved by endoglycosidase H. Trypsin readily cleaved the 123-kilodalton (kDa) form of glucosidase II into a fully active 73-kDa core. The pattern of this cleavage suggests a domain structure for this enzyme. We demonstrate that trypsin first removes a glycosylated 25-kDa domain to yield an apparently unglycosylated 98-kDa product which is further cleaved to yield the active 73-kDa core.

Animals↗
PubMed1985

Evidence that substance P and somatostatin transmit separate information related to pain in the spinal dorsal horn.

Effects of various types of natural skin stimuli on the in situ release of immunoreactive substance P and somatostatin from the rabbit dorsal horn were examined. Noxious mechanical or thermal stimuli specifically increased the release of immunoreactive substance P or somatostatin, respectively. Innocuous stimuli did not affect the release of these peptides. These results suggest that the nociceptive mechanical or thermal primary afferents contain substance P or somatostatin, respectively.

Animals↗
PubMed1985

Met-enkephalin and morphine but not dynorphin inhibit noxious stimuli-induced release of substance P from rabbit dorsal horn in situ.

The effects of locally applied opioids on the release of immunoreactive Substance P (iSP), induced by mechanical stimuli, from the dorsal horn of the rabbit in situ, were investigated. Morphine and met-enkephalin (met-enk), but not dynorphin A (1-17) (DYN), in a concentration of 10 microM, significantly inhibited the evoked release. These inhibitory effects of morphine and met-enkephalin were antagonized by the local application of naloxone (10 microM) to the dorsal horn. These results suggest that the inhibition of the release of Substance P induced by noxious mechanical stimuli may be mediated by mu and delta, but not by kappa opioid receptors.

Animals↗
PubMed1985

Retention of membrane proteins by the endoplasmic reticulum.

We have used a monoclonal antibody specific for a hydrocarbon-induced cytochrome P450 to localize, by electron microscopy, the epitope-specific cytochrome P450. The cytochrome was found in the rough and smooth endoplasmic reticulum (ER) and the nuclear envelope of hepatocytes. Significant quantities of cytochrome P450 were not found in Golgi stacks. We also could not find any evidence of Golgi-associated processing of the Asn-linked oligosaccharide chains of two well-characterized ER membrane glycoprotein enzymes (glucosidase II and hexose-6-phosphate dehydrogenase), or of the oligosaccharides attached to the bulk of the glycoproteins of the ER membrane. We conclude that these ER membrane proteins are efficiently retained during a process of highly selective export from this organelle.

Acetylglucosaminidase↗
PubMed1985

Effect of riboflavin-butyrate on cardiac glutathione reductase affected by adriamycin.

Male Wistar rats received intraperitoneal injections of adriamycin (4 mg/kg body weight/day) and/or riboflavin-butyrate (20 mg/kg body weight/day) for 6 consecutive days. Cardiac mitochondria were then prepared for our present experiment. The combined use of riboflavin-butyrate with adriamycin was evaluated for reduction of lipid peroxide formation in rat cardiac mitochondria. In order to find the mechanism of the effect of riboflavin-butyrate, the glutathione peroxidase-glutathione reductase system was examined. Adriamycin reduced the glutathione reductase activity in rat cardiac mitochondria, but did not affect the glutathione peroxidase activity. The mitochondrial content of flavin adenine dinucleotide, a prosthetic group of glutathione reductase, was greatly reduced and apoprotein of glutathione reductase also decreased. The administration of riboflavin-butyrate with adriamycin increased flavin adenine dinucleotide and glutathione reductase activity. These results suggest that exogenous administration of riboflavin-butyrate is capable of reducing lipid peroxide by both enzymatic detoxification through glutathione reductase and non-enzymatic detoxification due to direct reaction with lipid peroxide.

Animals↗
PubMed1983

Three immunoidentical cytochromes P-450 from liver microsomes of phenobarbital-treated rats.

Three forms of cytochrome P-450 were purified to homogeneity from liver microsomes of Wistar-strain rats treated with phenobarbital. They had minimum mol.wts. of 52 000, 53 000 and 54 000 as determined by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis and are designated as P-450(L), P-450(M) and P-450(H) respectively. They were shown to be immunoidentical by Ouchterlony double-diffusion analysis. Several criteria, such as isoelectric points, substrate specificities and sensitivities to tryptic digestion, however, indicated that these cytochromes are distinct isoenzymes of cytochrome P-450. Whereas P-450(L) was highly active on various substrates, P-450(H) had generally low catalytic activities, except on aminopyrine. The cytochromes purified by immunoaffinity chromatography using anti-P-450(L) showed a marked variation in their distribution depending on the strain and colony of rat. Limited tryptic digestion of P-450(H) gave one tryptic peptide showing the same mobility as P-450(L) by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis and their primary structures were very similar. The result suggests a possibility that such limited proteolysis is involved in the post-translational modification of the cytochrome or its destruction.

Animals↗
PubMed1983

Ribose. An oxidation product of glucose 6-phosphate in microsomal fraction.

An oxidative metabolism of glucose 6-phosphate was studied in rat liver microsomal fraction. Although radioactive 14CO2 was formed from [1-14C]glucose 6-phosphate in the microsomal fraction (Hino, Y., and Minakami, S. (1982) J. Biochem. (Tokyo) 92, 547-557), the formation was negligible when [2-14C]glucose 6-phosphate was used as a starting substrate. These results indicated an inability of the microsomal fraction to rearrange [2-14C]glucose 6-phosphate to form [1-14C] glucose 6-phosphate, and it was expected that a certain compound derived from glucose 6-phosphate accumulated as an end-product of the reaction. We, therefore, have tried to identify the product by high performance liquid chromatography, and found that ribose accumulated as the end-product. The formation of ribose was inhibited in the same manner as that of 14CO2 by antibodies against rat liver microsomal hexose-6-phosphate dehydrogenase, and the ratios of ribose to 14CO2 formed in the reaction were 0.5-0.8 on a molar basis. The finding of ribose formation further suggested the involvement of ribose phosphate isomerase and phosphatase activities in the reaction.

Animals↗
PubMed1983

[Case of disseminated necrotizing leukoencephalopathy following intrathecal methotrexate in acute lymphocytic leukemia].

Disseminated necrotizing leukoencephalopathy was found upon autopsy of a 32-year-old man with acute lymphocytic leukemia. He had been treated with intrathecal methotrexate for CNS involvement; no radiation therapy had been given. Autopsy findings revealed that in the white matter of the temporal lobe, there was widespread necrosis associated with numerous foam cells, demyelination, vacuolization and slight gliosis; in this lesion, leukemic cells infiltrated the Virchow-Robin space. In the white matter of other lesions we found discrete multifocal necroses of coagulative type associated with round or rod-shaped axonal swelling partly accompanied with calcification. However, in these lesions, there was no leukemic cell infiltration.

Adult↗
PubMed1982

Hexose-6-phosphate dehydrogenase of rat liver microsomes. Isolation by affinity chromatography and properties.

Hexose-6-phosphate dehydrogenase was purified from rat liver microsomal fraction more than 500-fold with a 45% recovery using DEAE-cellulose and 2',5'-ADP-Sepharose 4B columns. The purified enzyme appeared to be immunologically and electrophoretically homogeneous and had broad substrate and cofactor specificities. The enzyme activity was not inhibited by p-chloromercuribenzoate. The purified enzyme was a glycoprotein in nature, having a Stokes radius of about 55 A, a sedimentation coefficient of about 8.2 s, and an isoelectric point of about 6.4. Minimum molecular weight of the enzyme was about 108,000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, whereas the product cross-linked with glutaraldehyde or dimethyl suberimidate had Mr approximately equal to 220,000, suggesting that the active enzyme existed as a dimer of identical subunits. Antiserum raised against the purified enzyme inhibited the activity of the solubilized enzyme but did not inhibit the cytosol glucose-6-phosphate dehydrogenase activity. The antigenic sites of the enzyme were latent in intact microsomes. Comparison was also made between the enzymes isolated from untreated and phenobarbital-pretreated animals.

Animals↗
PubMed1982

Digital nerve grafts in replanted digits.

In most cases where digits have been amputated by avulsion and the digital nerve extensively injured, primary nerve suture cannot be performed. For such a digit when replanted, secondary nerve grafting was done under the operating microscope using a lateral femoral cutaneous nerve. Two years after operation, two-point discrimination of these cases proved to be 10.5 mm on average. And in the case of the transplanted three strand cable graft, using a lateral femoral cutaneous nerve yielded the most favourable results. The replacement was superior to the side receiving primary crushed nerve suture. Sensory nerve action potentials indicate that the regenerated nerve does not necessarily mature sufficiently. The recovery of sensitivity even to this degree however was sufficient for the replanted digits to be useful in all cases.

Action Potentials↗
PubMed1982

Hexose-6-phosphate and 6-phosphogluconate dehydrogenases of rat liver microsomes. Involvement in NADPH and carbon dioxide generation in the luminal space of microsomal vesicles.

Rat liver microsomal fraction generates 14CO2 from [1(-14)C]glucose 6-phosphate in the presence of NADP+ and a detergent. The activity is mediated through an enzyme system consisting of hexose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase inherent to the microsomes, with the latter enzyme reaction being a rate-determining step. Both enzymes of the system in microsomes are extremely resistant to trypsin digestion, thereby distinguishing them from the corresponding cytosol enzymes. A stoichiometric relationship was obtained between the generations of NADPH and 14CO2 (2: 1 on a molar basis), indicating that the observed generation of NADPH in microsomes could entirely be accounted for by the action of the enzyme system. A method was devised to measure NADP(H) inside or outside the microsomal vesicles, and it was found that a considerable amount of the cofactor was present within the vesicles. Subfractionation of various intracellular fractions on sucrose density gradients confirmed the close association of NADP(H) with liver microsomes. It is suggested that both enzymes of the system function to generate the reduced form of NADP+ in the luminal space of the endoplasmic reticulum, where NADP(H) and glucose 6-phosphate are available.

Animals↗