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Biomedical subjects

H Hirata

Publications and source records attributed to H Hirata.

At least 19 recordsLinked to original sources
PubMed1992

Effects of alcohols on fluorescence anisotropies of diphenylhexatriene and its derivatives in bovine blood platelets: relationships of the depth-dependent change in membrane fluidity by alcohols with their effects on platelet aggregation and adenylate cyclase activity.

The effects of three short-chain alkyl alcohols and benzyl alcohol on the membrane fluidity of bovine blood platelets were investigated by studies on the fluorescence anisotropies of diphenylhexatriene (DPH), its cationic trimethylammonium derivative (TMA-DPH) and its anionic propionic acid derivative (DPH-PA). These alcohols decreased the fluorescence anisotropy of DPH, which is thought to be located within the hydrophobic core of the membrane, in concentration ranges that inhibited platelet aggregation. On the other hand, they had little or no effects on the fluorescence anisotropy of DPH-PA which is thought to be located in the interfacial region of the lipid bilayer. Likewise, they had little or no effects on the fluorescence anisotropy of TMA-DPH, which is also thought to be located in the interfacial region of the lipid bilayer, either when the probe was located in the outer layer of the plasma membrane or when the probe was located in the inner membrane compartment. These results suggest that alcohols mainly increase the fluidity in the central region of the lipid bilayer. Consistent with their effects on the fluorescence anisotropy of DPH, these alcohols increased the intracellular cyclic AMP concentration. Thus alcohols may inhibit platelet function due to stimulation of adenylate cyclase, which is mediated by perturbation of the central region of the membrane lipid bilayer.

Adenylyl Cyclases↗
PubMed1992

Heterozygous abnormal fibrinogen Osaka III with the replacement of gamma arginine-275 by histidine has an apparently higher molecular weight gamma-chain variant.

Congenitally abnormal fibrinogen Osaka III with the replacement of gamma Arg-275 by His was found in a 38-year-old female with no bleeding or thrombotic tendency. Release of fibrinopeptide(s) by thrombin or reptilase was normal, but her thrombin or reptilase time in the absence of calcium was markedly prolonged and the polymerization of preformed fibrin monomer which was prepared by the treatment of fibrinogen with thrombin or reptilase was also markedly defective. Propositus' fibrinogen had normal crosslinking abilities of alpha- and gamma-chains. Analysis of fibrinogen chains on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) in the system of Laemmli only revealed the presence of abnormal gamma-chain with an apparently higher molecular weight, the presence of which was more clearly detected with SDS-PAGE of fibrin monomer obtained by thrombin treatment. Purified fragment D1 of fibrinogen Osaka III also seemed to contain an apparently higher molecular weight fragment D1 gamma remnant on Laemmli gels, which was digested faster than the normal control by plasmin in the presence of [ethylenebis(oxyethylenenitrilo)]tetraacetic acid (EGTA).

Adult↗
PubMed1992

Primary structure of the alanine carrier protein of thermophilic bacterium PS3.

Purified alanine carrier proteins were cleaved into peptides either chemically after solubilization in 1,1,1,3,3,3-hexafluoro-2-propanol or proteolytically with lysylendopeptidase. From the amino acid sequence analyses of these peptides, we synthesized a DNA probe and utilized it for successful cloning of a gene encoding the alanine carrier protein (acp gene). The 5'-flanking region was determined by an inverse polymerase chain reaction, and an open reading frame consisting of 1,335 nucleotides was found. The amino acid sequence deduced from the open reading frame consists of 445 amino acids, and all the partial amino acid sequences determined are included in the sequence. Although the calculated M(r) of 47,803 is significantly larger than the apparent M(r) of 42,500 as reported previously (Hirata, H., Kambe, T., and Kagawa, Y. (1984) J. Biol. Chem. 259, 10653-10656), an in vitro translation experiment revealed that the product of the acp gene migrates at a position coinciding with that of the purified alanine carrier. Hydropathy analysis suggests that the protein contains at least 8 hydrophobic segments presumably spanning membrane. A homology search on a database reveals relatively high scores of homology with either the Escherichia coli melibiose carrier or the human Na+/glucose symporter, particularly in the region from Leu246 to Glu286. Furthermore, the region also reveals low but significant similarities to other Na(+)-coupled symporters.

Amino Acid Sequence↗
PubMed1992

Post-ischemic administration of bifemelane hydrochloride prohibits ischemia-induced depletion of the muscarinic M1-receptor and its mRNA in the gerbil hippocampus.

Parallel determinations of muscarinic cholinergic M1 receptor (M1-R) binding and of M1-R mRNA levels were carried out in the gerbil hippocampus 14 days after 5 min of transient ischemia. Both were reduced in the ischemic tissue to about 50% of the levels found in sham-operated controls, indicating that the late loss of M1-R is probably dependent on decreased synthesis. Three administrations of bifemelane hydrochloride (15 mg/kg, i.p., just after ischemia and 6 and 12 h later) completely prevented neuronal death in the hippocampus and ischemia-induced losses of hippocampal M1-R and its mRNA. Since vascular dementia may depend upon the ischemia-induced losses in cholinergic communication in the hippocampus, these findings suggest that it may be possible to prevent its occurrence by post-ischemic treatment with bifemelane hydrochloride.

Animals↗
PubMed1992

Simple and high-yield purification of urine protein 1 using immunoaffinity chromatography: evidence for the identity of urine protein 1 and human Clara cell 10-kilodalton protein.

A simple and high-yield purification procedure for urine protein 1 (UP1) using anti-UP1 immunoaffinity chromatography is described. Pure UP1 was obtained in a final yield of 60.2%, and observed as a single electrophoretic band and as a single peak on reversed-phase high-performance liquid chromatography. The N-terminal amino acid residue of UP1 was found to be glutamic acid, contrary to what was reported previously. Furthermore, the N-terminal sequence of UP1 up to 53 amino acids was confirmed to be identical with that of mature human Clara cell 10-kilodalton protein, which inhibits phospholipase A2 activity.

Amino Acid Sequence↗
PubMed1992

Late onset and long-lasting suppressive effects of ceruletide, an analogue of cholecystokinin, on c-fos mRNA expression in the rat striatum.

C-fos mRNA expression by stimulation with subcutaneous (s.c.) administration of saline or cycloheximide (CHX) was examined in the rat striatum with or without pretreatment with ceruletide, an analogue of cholecystokinin. The c-fos mRNA induction 1 h after CHX stimulation (25 mg/kg, s.c.) was significantly suppressed by ceruletide pretreatment (80 micrograms/kg, s.c.) 2 h before CHX stimulation in the striatum, and tended to be suppressed by ceruletide pretreatment 4 h before saline or CHX stimulation. Long-lasting and inhibitory effects of ceruletide on dyskinesia and on dopaminergic (DAergic) neuronal systems, and c-fos mRNA expression by activation of the DAergic system have been reported. The present findings together with previous reports suggest that ceruletide might have late onset and long-lasting suppressive effects on the expression of c-fos mRNA in the striatum and that these effects might be related to its effects on DAergic neuronal transmission.

Animals↗
PubMed1992

Characterization of an abnormal fibrinogen Osaka V with the replacement of gamma-arginine 375 by glycine. The lack of high affinity calcium binding to D-domains and the lack of protective effect of calcium on fibrinolysis.

Prolonged thrombin time was completely corrected by the addition of millimolar concentrations of calcium in a new abnormal fibrinogen, Osaka V. Analysis of lysyl endopeptidase digests of A alpha-, B beta-, or gamma-chains by high performance liquid chromatography, and the following amino acid sequence analysis of relevant peptides revealed that about 50% of the gamma-chain has a replacement of gamma-arginine 375 by glycine. When fibrinogen was digested with plasmin in the presence of millimolar concentration of calcium, the amount of fragment D1 was about 50% of the normal control, and the rest was further cleaved to fragment D2, D3, or D62 with an apparent Mr of 62,000. Plasmic digestion of cross-linked fibrin in the presence of calcium resulted in the appearance of an abnormal fragment with an apparent Mr of 123,000 as well as fragments D2, D3, and D62, concomitant with the decrease of D dimer. The gamma-remnant of the abnormal fragment proved to be a cross-linked complex of the normal D1 gamma-remnant and residues 374-406/411 of the abnormal gamma-chain. The number of high affinity Ca(2+)-binding sites for the normal fibrinogen and fibrinogen Osaka V obtained by equilibrium dialysis was 2.88 (about 3) and 1.85, respectively, and that for the abnormal molecules was calculated as 0.9 (about 1) from their relative amounts in the samples, suggesting the lack of two Ca(2+)-binding sites in the D-domains. These data suggest that the normal structure of the COOH-terminal portion of the gamma-chain including residue 375 is required for the full expression of high affinity calcium binding to D-domains, the ability to be protected by calcium against plasmic digestion, and fibrin polymerization. During these studies, we found that the NH2-terminal amino acid of the gamma-remnant in fragments D or D dimer which were obtained after prolonged digestion with plasmin is gamma-Met89.

Adult↗
PubMed1992

Comparison of the effects of bifemelane hydrochloride, idebenone and indeloxazine hydrochloride on ischemia-induced changes in brain monoamines and their metabolites in gerbils.

Bifemelane hydrochloride (bifemelane), idebenone and indeloxazine hydrochloride (indeloxazine) are used clinically to reduce apathy and other emotional disturbances in patients with cerebrovascular disease. In gerbil brains, ischemia affects many monoaminergic neurotransmitters and their metabolites. In the present study, the effects of treatment with bifemelane, idebenone and indeloxazine on ischemia-induced changes in monoamines and their metabolites were studied in ischemic gerbil brains. Although these drugs had no effect on the monoaminergic neurotransmitters or their metabolites in sham-operated animals, in the ischemic brains both dopamine and serotonin turnovers were abnormal after idebenone or indeloxazine treatment. Bifemelane, in contrast, tended to correct the ischemia-induced changes in the dopaminergic and serotonergic systems in the cerebral cortex, hippocampus and thalamus + midbrain. From the present results and those in previous reports, we conclude that bifemelane is more appropriate than idebenone or indeloxazine as a treatment for the ischemia-induced changes in monoaminergic neurotransmitter systems.

Animals↗
PubMed1992

Opposite effects of rough and gentle handling with repeated saline administration on c-fos mRNA expression in the rat brain.

The rough handling with repeated saline administration (1.2 ml/kg s.c. for 7 days) enhanced cortical c-fos mRNA expression in the rat brain after a single saline stimulation (1.2 ml/kg s.c.) due to increasing baseline c-fos mRNA levels, whereas the gentle handling with repeated saline administration declined c-fos mRNA expression after a single injection due to decreasing the baseline of c-fos mRNA levels. These two types of handling with the repeated injection led to diametrically opposite results on c-fos mRNA expression after a single stimulation. Neither two types of handling with repeated saline injections affected the net increment of c-fos mRNA induction after a single stimulation, therefore, the effects of handling with repeated treatment on c-fos mRNA expression might be independent of the effects of a single saline stimulation. The present study suggests that c-fos mRNA induction after a single stimulation might be affected by the types or intensities of handling and that care must be taken to estimate c-fos mRNA induction.

Animals↗
PubMed1992

Muscarinic cholinergic receptor-mediated modulation on striatal c-fos mRNA expression induced by levodopa in rat brain.

To clarify the interactions between dopamine receptors and muscarinic cholinergic receptors by which neurotransmitters may affect genetic responses, we studied the effects of the muscarinic cholinergic agonist, carbachol, and the muscarinic cholinergic antagonist, trihexyphenidyl, on levodopa-induced c-fos messenger RNA (mRNA) expression in rat striatum. Animals were administered levodopa (levodopa with one-tenth dosage of carbidopa), carbachol or thrihexyphenidyl alone or administered in combination as levodopa (100 mg/kg) + carbachol, or levodopa+trihexyphenidyl given as a single bolus. Levodopa given alone increase the expression of c-fos mRNA. Although carbachol or trihexyphenidyl alone was ineffective in inducing c-fos mRNA, the combination of levodopa and carbachol (> or = to 0.1 mg/kg) significantly suppressed the induction of c-fos mRNA as compared with levodopa given alone. The combined administration of levodopa and trihexyphenidyl showed a trend toward an additive effect on the induction of c-fos mRNA vs levodopa alone. These findings suggest that the muscarinic cholinergic system may modulate the levodopa-induced c-fos mRNA expression which then regulates the expression of other mRNAs.

Actins↗
PubMed1992

Effects of chronic catecholamine depletions on muscarinic M1-receptor and its mRNA in rat brain.

In order to compare the effects of total catecholamine (CA) or noradrenaline (NA) depletions on cholinergic systems, and the mechanisms of receptor regulation in various brain regions, the regional changes in the levels of acetylcholine (ACh), M1-receptor (M1-R) binding, and M1-R messenger RNA (mRNA) were mainly examined in rats which had received either repeated reserpine treatment or a single injection of the selective noradrenergic neurotoxin N-2-chloroethyl-N-ethyl-2-bromo-benzylamine (DSP-4). The levels of dopamine (DA), its metabolites, NA, binding to both D1 and D2 sites, and the mRNA encoding the D2 receptor were also measured. Administration of reserpine (0.5 mg/kg/day, s.c.) for 2, 7 and 14 days depleted DA and NA in virtually all brain regions, while the short-term treatment increased DA metabolites in the striatum (at 2 days) and basal forebrain (at both 2 and 7 days). Administration of DSP-4 (50 mg/kg, i.p.) resulted in a specific loss of NA in the brain 10 days after the injection. These DSP-4 treated rats showed no change in the levels of ACh or M1-R except for an increase in ACh in the frontal cortex. In contrast, numerous changes in cholinergic indices were seen in the reserpine treated groups, and these changes varied from region to region of brain and with the length of drug treatment. In the striatum, ACh levels were increased in rats treated for 2 or 7 days but were normal after 14 days. M1-Rs were decreased at 14 days. These changes suggest that striatal DA, initially released by reserpine, inhibits the release of ACh from striatal cholinergic interneurons, while prolonged depletion of DA relieves this inhibition, leading to a subsequent down-regulation of M1-Rs. In the frontal cortex, ACh and M1-R levels were all decreased by reserpine treatment for 2 or 7 days, and the M1-Rs remained depressed at 14 days. In the basal forebrain, which contains the cholinergic cells that project to the cortex, DA metabolism was increased by 2 or 7 day reserpine treatment. This increased DAergic activity in the basal forebrain may facilitate cholinergic neurons, causing increased release of ACh in the frontal cortex. This, in turn, may lead to a down-regulation of the M1-Rs in that region. The levels of mRNAs encoding M1-Rs were increased in the striatum and frontal cortex by reserpine treatment, despite the decreases in the M1-Rs themselves.(ABSTRACT TRUNCATED AT 400 WORDS)

3,4-Dihydroxyphenylacetic Acid↗
PubMed1992

Changes of neuropeptides and their receptors in experimental stroke gerbil brains.

Eight kinds of neuropeptides and four kinds of neuropeptide receptors were examined in the right and left hemispheres of mongolian gerbils after unilateral carotid ligation-induced stroke and in normal controls. Five hours after ligation of the right common carotid artery, beta-endorphin concentration in the right hemisphere (ischemic side) of the stroke group was significantly increased compared with that in the contralateral hemisphere (non-ischemic side), but there were no differences between sides in other neuropeptides either with or without stroke. Furthermore, although there were no differences in [3H]naloxone binding, [3H]thyrotropin-releasing hormone binding or 125I-vasoactive intestinal polypeptide binding in the brain in this model of stroke, [3H]enkephalin binding was significantly lower on the ischemic side than on the non-ischemic side in the stroke group. These results suggest that increased activity in the beta-endorphinergic system in the brain might be partly caused by ischemic brain failure.

Animals↗
PubMed1992

Partial purification and reconstitution of inositol 1,4,5-trisphosphate receptor/Ca2+ channel of bovine liver microsomes.

The binding of inositol-1,4,5-trisphosphate [Ins(1,4,5)P3] to bovine liver microsomes was characterized. The Ins(1,4,5)P3 receptor of the microsomes was solubilized by 1% Triton X-100 and purified by sucrose density gradient, Heparin-Sepharose, DEAE-Toyopearl, ATP-Agarose, and Ins(1,4,5)P3-Sepharose column chromatographies. More than 1,000-fold enrichment of the Ins(1,4,5)P3-binding activity was achieved. Kd values of the binding activity were 2.8 nM in microsomes and 3.0 nM in the partially purified receptor, respectively, and the binding activity was optimal in the medium containing 100 mM KCl and at pH between 7.5 and 8.5. The presence of Ca2+ failed to inhibit the binding. Phosphatidylethanolamine (PE), phosphatidylcholine (PC), phosphatidylserine (PS), phosphatidylinositol (PtdIns), and phosphatidylinositol-4-monophosphate [PtdIns(4)P] showed no effect on the Ins(1,4,5)P3 binding. However, soybean phospholipids asolectin and phosphatidylinositol-4,5-bisphosphate [PtdIns(4,5)P2] strongly inhibited the binding activity. PtdIns(4,5)P2 inhibited the activity competitively with a half-maximal inhibitory concentration of 30 micrograms/ml. The partially purified Ins(1,4,5)P3 receptor was reconstituted into proteoliposomes. Fluorescence measurements using Quin 2 indicated that Ins(1,4,5)P3 stimulated Ca2+ influx into the proteoliposomes. The EC50 of Ins(1,4,5)P3 on Ca2+ influx was 50 nM. This result strongly suggest that Ins(1,4,5)P3 binding protein of liver microsomes acts as a physiological Ins(1,4,5)P3 receptor/Ca2+ channel.

Animals↗
PubMed1992

Interaction of rhodopsin, G-protein and kinase in octopus photoreceptors.

Light induced phosphorylation of octopus rhodopsin was greatly enhanced by guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S), suggesting that the kinases are involved in regulating interaction between rhodopsin and G-protein. We determined phosphorylated peptides of octopus rhodopsin in the presence or absence of GTP gamma S. Possible phosphorylation sites for octopus rhodopsin enhanced by GTP gamma S were Thr329, Thr330 and/or Thr336, which suggest that the G-protein associates with cytoplasmic loops including C-terminal peptide in the seventh helix of octopus rhodopsin.

Amino Acid Sequence↗
PubMed1992

Fibrinogen Lima: a homozygous dysfibrinogen with an A alpha-arginine-141 to serine substitution associated with extra N-glycosylation at A alpha-asparagine-139. Impaired fibrin gel formation but normal fibrin-facilitated plasminogen activation catalyzed by tissue-type plasminogen activator.

An A alpha-arginine-141 to serine substitution has been identified in a homozygous dysfibrinogen, fibrinogen Lima, associated with impaired fibrin polymerization. The point mutation created an asparagine-X-serine-type glycosylation sequence, and indeed, extra, mainly disialylated biantennary oligosaccharides have been isolated from A alpha asparagine-139 of the patient's fibrinogen. This type of glycosylation sequence is unique for human fibrinogen, because the sequences shown for normal and abnormal fibrinogens are all asparagine-X-threonine types. The terminal sialic acids of the extra oligosaccharides seem to have largely contributed to the impaired fibrin gel formation, as evidenced by its correction to a near normal level by desialylation. Nevertheless, the polymerizing fibrin facilitated tissue-type plasminogen activator-catalyzed plasmin formation in a normal fashion, indicating that the initial two-stranded fibrin protofibrils had been constructed normally. Thus the impaired fibrin gel formation could be attributed to the delay in their subsequent lateral association, most probably because of the repulsive forces generated by the negative electric charge of the extra sialic acids. The substitution of a basic residue arginine to a noncharged residue serine may also have contributed to the impaired function in a similar manner or by steric hindrance in association with bulky extra oligosaccharide chains.

Amino Acids↗
PubMed1992

Development of a simple spasticity quantification method: effects of tizanidine on spasticity in patients with sequelae of cerebrovascular disease.

A simple method that can be performed at the bedside using a spring balance was developed in order to quantify spasticity. The effects of tizanidine on spasticity were evaluated in 30 patients with sequelae of cerebrovascular disease using this method. Treatment with tizanidine was effective in 60% of the patients; there were high correlations between spasticity before and after tizanidine administration and the severity of symptoms and also between the degree of improvement in spasticity and in that of the symptoms. Atonic seizures, due to overdose of tizanidine, were observed in only one patient. The simple spasticity quantification method developed was useful for monitoring tizanidine administration in order to prevent drug overdose. The method appears to be very useful for evaluating the degree of spasticity at the bedside and in measuring the effects of antispastic drugs.

Aged↗
PubMed1992

Age-related changes in cerebrospinal fluid gamma-aminobutyric acid concentration.

The purpose of this study was to clarify the effect of aging on brain gamma-aminobutyric acid metabolism. We measured the cerebrospinal fluid gamma-aminobutyric acid concentration in subjects of various ages, including healthy volunteers and patients without neurological or psychiatric disease. The cerebrospinal fluid gamma-aminobutyric acid concentration was determined by radiolabelled receptor assay using [3H]gamma-aminobutyric acid. Cerebrospinal fluid gamma-aminobutyric acid was significantly higher in the control group (20s and 30s) than in the groups of subjects in their 50s, 60s, 70s and 80s. There was a significant negative correlation between cerebrospinal gamma-aminobutyric acid concentration and age (p less than 0.01). These data suggest that dysfunction of brain gamma-aminobutyric acid metabolism increases with age, and that the various symptoms caused by abnormal gamma-aminobutyric acid metabolism in the brain are therefore more likely to appear in elderly people.

Adult↗