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Biomedical subjects

M Hirai

Publications and source records attributed to M Hirai.

At least 145 records · Page 8Linked to original sources
PubMed1998

The effects of coenzyme Q10 treatment on maternally inherited diabetes mellitus and deafness, and mitochondrial DNA 3243 (A to G) mutation.

The characteristic clinical features of diabetes mellitus with mitochondrial DNA (mtDNA) 3243(A-G) mutation are progressive insulin secretory defect, neurosensory deafness and maternal inheritance, referred to as maternally inherited diabetes mellitus and deafness (MIDD). A treatment for MIDD to improve insulin secretory defects and reduce deafness has not been established. The effects of coenzyme Q10 (CoQ10) treatment on insulin secretory response, hearing capacity and clinical symptoms of MIDD were investigated. 28 MIDD patients (CoQ10-DM), 7 mutant subjects with impaired glucose tolerance (IGT), and 15 mutant subjects with normal glucose tolerance (NGT) were treated daily with oral administration of 150 mg of CoQ10 for 3 years. Insulin secretory response, blood lactate after exercise, hearing capacity and other laboratory examinations were investigated every year. In the same way we evaluated 16 MIDD patients (control-DM), 5 mutant IGT and 5 mutant NGT subjects in yearly examinations. The insulin secretory response assessed by glucagon-induced C-peptide secretion and 24 h urinary C-peptide excretion after 3 years in the CoQ10-DM group was significantly higher than that in the control-DM group. CoQ10 therapy prevented progressive hearing loss and improved blood lactate after exercise in the MIDD patients. CoQ10 treatment did not affect the diabetic complications or other clinical symptoms of MIDD patients. CoQ10 treatment did not affect the insulin secretory capacity of the mutant IGT and NGT subjects. There were no side effects during therapy. This is the first report demonstrating the therapeutic usefulness of CoQ10 on MIDD.

Adult↗
PubMed1998

Changes in urinary 6beta-hydroxycortisol/cortisol ratio after birth in human neonates.

OBJECTIVE: Urinary 6beta-hydroxycortisol/cortisol (6beta-OHF/C) ratio was measured in human neonates to assess the CYP3A enzyme activity. METHODS: Urinary 6beta-OHF/C ratio was determined on the day of birth in 94 neonates including those born prematurely. In addition, changes in the ratios after birth were also determined in 81 neonates. RESULTS: On the day of birth, a significant positive correlation was found between urinary 6beta-OHF/C ratios and gestational age (r = 0.476) and birth weight (r = 0.283). There was no gender difference in the urinary 6beta-OHF/C ratios in human neonates. Furthermore, delivery modes such as cesarean section and vaginal delivery did not appear to affect the urinary 6beta-OHF/C ratio. The mean ratio of urinary 6beta-OHF/C observed in 39 mature neonates (more than 37 weeks of gestational age) was higher than that observed in adults (16.5 vs 9.9). Within 5 days after birth, the ratio rapidly decreased to less than that in adults. In contrast, the mean ratio of urinary 6beta-OHF/C observed in 42 premature neonates (under 37 weeks of gestational age) was significantly lower than that observed in mature neonates (5.3 vs 16.5) and was virtually unchanged during the 14-days after birth. Therefore, no significant difference was observed in the mean ratio of urinary 6beta-OHF/C between mature and premature neonates at 5 days after birth. CONCLUSION: From these results, it was concluded that on the day of birth, mature neonates might possess a higher activity of CYP3A enzyme compared with premature neonates, and that the CYP3A enzyme activity in mature neonates might be promptly changed at an early stage after birth.

Aryl Hydrocarbon Hydroxylases↗
PubMed1998

Interaction of gangliosides with proteins depending on oligosaccharide chain and protein surface modification.

By using neutron and synchrotron x-ray small-angle scattering techniques, we investigated the process of the complexation of gangliosides with proteins. We treated monosialoganglioside (G(M1)), disialoganglioside (G(D1a)), and a mixture of G(M1)/G(D1a). Proteins used were bovine serum albumins whose surfaces were modified with different sugars (deoxy-D-galactose, deoxy-L-fucose, deoxymaltitol, and deoxycellobiitol), which were used as model glycoproteins in a membrane. We found that the complexation of gangliosides with albumins greatly depends on the combination of ganglioside species and protein surface modification. With a varying protein/ganglioside ratio in a buffer solution at pH 7, the complexation of G(M1) or G(D1a) with albumins modified by monosaccharides appears to be less destructive for ganglioside aggregate structures in forming large complexes; the complexation of G(D1a) with the albumins modified by disaccharides induces the formation of complexes with a dimeric structure; and the complexation of G(M1) with albumins modified by disaccharides, to form small complexes, is very destructive. The present results show a strong dependence of the interaction between ganglioside and protein on the characteristics of the ganglioside and protein surface, which would relate to a physiological function of gangliosides, such as a function regulating the receptor activity of glycoproteins in a cell membrane.

Animals↗
PubMed1998

Intensive extrusion and occlusion of water in ganglioside micelles with thermal reversibility.

By using a shell-modeling analysis for small-angle scattering data of ganglioside micellar dispersion, we recently reported that the elevation of temperature induces a significant shrinkage of the hydrophilic region of the ganglioside micelle, suggesting that the oligosaccharide chains with sialic acid residues of ganglioside molecules change the conformation, sensitively responding to a change in temperature (Hirai et al., 1996. Biophys. J. 70:1761-1768; J. Phys. Chem. 100:11675-11680). We have carried out further analyses of the temperature dependence of the structural parameters reported previously, and we have found clear evidence of reversible extrusion and occlusion of a large amount of water in the hydrophilic region of the ganglioside micelle in the physiological temperature range of 6-60 degrees C. The present results suggest a remarkable function of ganglioside molecules: they change the hydrophilicity of the cell surface locally as a response to variations in temperature. This phenomenon might be involved in various surface events, such as cell-cell interaction and cell surface-protein interaction.

Animals↗
PubMed1998

Identification and cDNA cloning of novel juvenile hormone responsive genes from fat body of the bean bug, Riptortus clavatus by mRNA differential display.

Juvenile hormone (JH) induces termination of diapause and initiation of reproductive maturation in the adult female bean bug, Riportus clavatus. Applying PCR-based differential display, we have identified four novel JH-responsive cDNAS, that is, three repressible (JR-1, 2 and 3) and one inducible (JI-1). These DNA fragments were partially sequenced and compared with sequences in the data base. JR-3 was shown to have similarity to the transferrins of other insects, which have been reported as JH-suppressed genes. JI-1 has similarity to vitellogenin of Aedes aegypti. On the other hand, JR-1-1 and 2 have no significant similarity to other known sequences. For JR-1, the full cDNA sequence was determined: it contained 913 bp, encoding 194 amino acid residues with a calculated M.W. of 21,531 Da in the mature protein. A total of six JH-responsive genes or cDNAs (four suppressible and two inducible or stimulated), including the already isolated JH-responsive cyanoprotein genes (CP-alpha and beta), have been isolated and are available for further comparative analysis of gene structure and regulatory mechanisms in the same tissue under the same hormonal conditions.

Amino Acid Sequence↗
PubMed1998

Nucleotide sequence of vitellogenin mRNA in the bean bug, Riptortus clavatus: analysis of processing in the fat body and ovary.

The bean bug, Riptortus clavatus, has immunologically distinct yolk proteins, vitellin (Vn)-1 and-2 and their precursors, vitellogenin (Vg)-1 and-2. We have cloned the full nucleotide sequence of Vg-1 cDNA. The deduced amino acid sequence has some similarities to other insect Vgs. It contains two polyserine regions, which are characteristic of other Vgs. Vg-1 mRNA appeared after treatment with the juvenile hormone analogue, methoprene, implying transcriptional regulation. We found four enzymatic cleavage sites in the Vg molecule. Two of them match the consensus for dibasic processing endoprotease, which is also conserved in processing sites for other insect Vgs. We showed that the processing at each site was incomplete, and this resulted in production of more than the five polypeptides which would be expected from four processing sites in the molecule. The physiological significance of multiple polypeptides in insect Vgs is still unclear.

Amino Acid Sequence↗
PubMed1998

cDNA cloning of human DNase gamma: chromosomal localization of its gene and enzymatic properties of recombinant protein.

We report here on the nucleotide sequence of the cDNA encoding human DNase gamma, which is a candidate for an apoptotic endonuclease. The cDNA clone isolated from a human spleen cDNA library is composed of a 918 bp open reading frame encoding a 305 amino acid precursor protein for DNase gamma. Northern blot analysis reveals that the expression of a single transcript of 1.5 kb DNase gamma mRNA is detected in the spleen and liver. The chromosomal localization of DNase gamma gene is mapped to chromosome 3 at region p21.1-p14.2 by fluorescence in situ hybridization (FISH). Characterization of thioredoxin-DNase gamma fusion protein (Trx-hDNase gamma) shows that the recombinant protein has a Ca(2+)/Mg(2+)- or Mn(2+)-dependent endonuclease activity that cleaves chromatin DNA to nucleosomal units. The optimum pH is around 7.2. Zn(2+) and aurintricarboxylic acid (ATA) inhibits the activity in dose-dependent manners. These properties are identical to those of purified DNase gamma.

Journal Article↗
PubMed1998

Expression of alpha-fetoprotein and prostate-specific antigen genes in several tissues and detection of mRNAs in normal circulating blood by reverse transcriptase-polymerase chain reaction.

BACKGROUND: alpha-Fetoprotein (AFP) and prostate-specific antigen (PSA) in serum are widely used as tumor markers in the evaluation of prognosis and management of patients with hepatocellular carcinoma and prostate cancer, respectively. To establish the molecular diagnosis of cancer, reverse transcriptase polymerase chain reaction (RT-PCR) for AFP and PSA was used to identify circulating cancer cells in the blood of cancer patients. Here, we examined the tissue-specificity of AFP and PSA and tested whether AFP and PSA are suitable targets in the detection of certain cancer cells by RT-PCR using peripheral blood samples. METHODS: Tissue specificity of AFP and PSA was analyzed by Northern blotting and RT-PCR. Probes for AFP and PSA were hybridized with poly A+ RNAs from 50 human tissues. RT-PCR for AFP and PSA mRNA was performed using several cancerous tissues and normal tissues and peripheral blood cells from seven healthy volunteers. RESULTS: Broad expression of AFP was observed in several tissues and a large amount of AFP mRNA was found in fetal liver. PSA was expressed in prostate, salivary gland, pancreas and uterus. By RT-PCR, AFP and PSA mRNA were detected in several tumors, including salivary pleomorphic adenoma, hilar bile duct carcinoma, pancreatic carcinoma, transitional cell carcinoma of urinary bladder and thyroid papillary carcinoma. Furthermore, AFP and PSA mRNAs were frequently detected by RT-PCR, even in peripheral blood cells from healthy volunteers. CONCLUSIONS: Neither AFP nor PSA showed tissue-specific expression. AFP and PSA mRNA were detected in several diseased and non-diseased tissues and normal circulating blood by RT-PCR.

Adenoma, Pleomorphic↗
PubMed1998

Molecular characterization of the mouse mtprd gene, a homologue of human TPRD: unique gene expression suggesting its critical role in the pathophysiology of Down syndrome.

We and others recently isolated a human TPRD gene, possessing a motif of the tetratricopeptide repeat (TPR), from the Down syndrome-critical region (DCR) of chromosome 21q22.2. In this study, we isolated a mouse homologue of TPRD cDNA, mtprd, and examined its expression profile in mouse embryos. The gene was mapped to mouse chromosome 16C3.3-4, consistent with the location of DCR, and encodes 1,979 amino acid residues with 76% identity to TPRD. The mtprd protein has three units of the TPR motif with 91% homology to TPRD. The protein also has two regions homologous to several matrix proteins with 86 and 70% identities to those of TPRD. Several splicing variants of the 5' portion of the open reading frame of mtprd were identified by RT-PCR and sequencing of mRNAs. In situ hybridization showed that mtprd is ubiquitously expressed in mouse embryos but predominantly in the central nervous system, including the telencephalon, mesencephalon, and metencephalon. These results suggest that the TPRD gene is one of the genes responsible for not only the morphological anomalies but also the neurological abnormalities observed in Down syndrome. The presence of splicing variants indicates that the protein may also have several isoforms in mice.

Amino Acid Sequence↗
PubMed1998

L-galactono-gamma-lactone dehydrogenase from sweet potato: purification and cDNA sequence analysis.

L-Galactono-gamma-lactone dehydrogenase (EC 1.3.2.3, GLDHase) was partially purified from mitochondria of sweet potato tuberous roots over 600-fold on a specific activity basis, followed by purification of the enzyme protein of 56 kDa by a preparative SDS-PAGE. The absorption spectrum of the hydroxylapatite column-purified GLDH-ase showed peaks at 448 and 373 nm, suggesting the presence of flavin as a prosthetic group. The activity of GLDH-ase was inhibited by lycorine, an alkaloid which inhibits ascorbic acid biosynthesis in vivo. N-terminal partial sequences of four internal polypeptides generated by partial digestion of GLDHase with V8 protease were determined. The deduced nucleotide sequences were used to amplify a cDNA fragment of the GLDHase gene. The clone encoded a polypeptide of 581 amino acid residues with a molecular mass of 66 kDa. The deduced amino acid sequence showed 77% identity with that of cauliflower GLDHase, and significant homology to those of L-gulono-gamma-lactone oxidase (22% identity) from rat and L-galactono-gamma-lactone oxidase from yeast (17% identity), which are enzymes involved in L-ascorbic acid biosynthesis in these organisms. The absorption spectrum and cDNA sequence suggested that the flavin group bound noncovalently. We conclude that GLDHase, L-gulono-gamma-lactone oxidase and L-galactono-gamma-lactone oxidase are homologous in spite of the difference in substrates and electron acceptors. Genomic Southern analysis suggested that GLDHase gene exists as a single copy in the genome of sweet potato.

Amaryllidaceae Alkaloids↗
PubMed1998

Staged reperfusion preserves the coronary flow reserve, especially in the regions not severely damaged by ischemic injury in the canine heart.

The objective of this study was to determine the effects of staged reperfusion on the progressive reduction in coronary blood flow (CBF) and coronary flow reserve during reperfusion and on the infarct size in the canine heart. Fifteen dogs underwent 90 min of left circumflex coronary artery occlusion and 3 hr of reperfusion. In the abrupt reperfusion group, the occluder was released completely at the initiation of reperfusion. In the staged reperfusion group, CBF was maintained at 20% of preocclusion values for 10 min after initiation of reperfusion, then gradually released, and completely released 20 min after initiation of reperfusion. There was no significant difference in CBF between the staged (n = seven) and abrupt (n = eight) groups after 3 hr of reperfusion. The repayment of flow debt in the staged reperfusion group was significantly greater than in the abrupt reperfusion group after 3 hr of reperfusion (260+/-120% vs 100+/-60%, staged vs abrupt at 3 hr, p < 0.03). The ratio of peak reactive hyperemic flow to resting flow in the staged reperfusion group was significantly greater than in the abrupt reperfusion group throughout the reperfusion phase (4.4+/-1.0 vs 2.6+/-0.6 at 3 hr, p < 0.001), and had returned to the preocclusion values after 3 hr of reperfusion. This preservation of the coronary flow reserve in the staged reperfusion group was observed in the epicardium (4.1+/-0.6 vs 2.8+/-0.7, staged vs abrupt at 3 hr, p < 0.01), but not in the endocardium or midmyocardium. Infarct size did not differ significantly between the two groups. Staged reperfusion in this study did not appear to attenuate the reduction of CBF, or to reduce infarct size, however preserved the coronary flow reserve, especially in the regions not severely damaged by ischemic injury.

Animals↗
PubMed1998

Mitochondrial deoxyribonucleic acid 3256C-T mutation in a Japanese family with noninsulin-dependent diabetes mellitus.

Accumulating reports indicate a relationship between mitochondrial DNA mutation and impaired glucose-induced insulin secretion leading to a subtype of noninsulin-dependent diabetes mellitus. DNA from a 45-yr-old Japanese woman with noninsulin-dependent diabetes mellitus and muscle atrophy was isolated and studied for mitochondrial DNA mutations. We identified a mitochondrial DNA C-T heteroplasmic mutation at nucleotide position 3256. The mutation was located in the transfer ribonucleic acidLeu in a region conserved in evolution. Eight other members of her family were examined for the mutation. Six of them had the same mutation together with noninsulin-dependent diabetes mellitus, and one teenage boy had the mutation and impaired glucose tolerance. The other family member who did not have this mutation had normal glucose tolerance. The enzyme activity of the mitochondrial oxidative phosphorylation pathway in the muscle of the proband was measured. The enzyme activity was decreased in the proband, especially in complex I. This mutation might be responsible for the abnormal glucose metabolism.

Adolescent↗
PubMed1998

Change in erythrocyte shape induced by cyclosporine administration.

In order to estimate the effect of the long term administration of cyclosporine (CsA) on the shape change of erythrocytes, erythrocyte shapes which are observed with a scanning electron microscope were classified according to the nomenclature of Bessis for stomatocyte-echinocyte shape transformation. As a result of observing the erythrocyte shape of fifty-six patients with kidney transplantation treated with CsA, the morphological index of the erythrocytes of patients significantly increased to 0.0835+/-0.0085*** in comparison with 0.0004+/-0.0051 of those from healthy volunteers (control) (***: p<0.001, ANOVA). Such transformations had no relation to the subjects' sex or age. On the other hand, the erythrocytes of patients administered more than 100 ng/ml of CsA and posttransplanted within less than two years were transformed by CsA from the state of discocyte to echinocyte. In rats, the morphological index of erythrocytes of rats treated with 3 mg/kg/d or 5 mg/kg/d of CsA significantly increased in comparison with rats treated with saline (control). Furthermore, the erythrocytes of two patients were observed in terms of shape before the treatment with CsA. In both patients, the echinocyte type of erythrocyte increased by treatment with CsA. In vitro, the morphological index of the erythrocytes incubated with plasma containing CsA significantly increased, to 0.459+/-0.066*** in comparison with 0.064+/-0.029 of the control. It is suggested from these results that CsA treatment induces the echinocyte type of erythrocyte.

Adult↗
PubMed1998

Cloning of cDNA for a cell wall-bound acid invertase from tomato (Lycopersicon esculentum) and expression of soluble and cell wall-bound invertases in plants and wounded leaves of L. esculentum and L. peruvianum.

A cDNA, Wiv-1, for an isozyme of acid invertase (EC 3.2.1.26) was cloned from wounded leaves of tomato (Lycopersicon esculentum). The encoded protein had a basic isoelectric point and strong similarity to the amino acid sequences of plant cell wall-bound invertases. The conserved sequence WECPD that is found in all plant cell wall-bound invertases was also found in the deduced protein. These results suggested that Wiv-1 encoded a cell wall-bound acid invertase of tomato. Wounding increased the levels of mRNAs for soluble and cell wall-bound invertases and the activities of these invertases in leaves of L. esculentum and of a related species, L. peruvianum. The induction of Aiv-1 mRNA for the soluble enzyme in wounded leaves was not very strong, while that of Wiv-1 mRNA for the wall-bound enzyme was prominent. The level of Aiv-1 mRNA reached a maximum 48 h after wounding while that of Wiv-1 mRNA continued to rise for up to 96 h. These findings suggested that the genes for the two isozymes responded independently to wounding. The levels in various organs of Aiv-1 and Wiv-1 mRNAs were higher in L. esculentum than in L. peruvianum. Possible roles of cell wall-bound acid invertase in wound response and in developing plant are discussed.

Amino Acid Sequence↗