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Biomedical subjects

M Hirata

Publications and source records attributed to M Hirata.

At least 19 recordsLinked to original sources
PubMed1992

Sexual transmission of hepatitis C virus among female prostitutes and patients with sexually transmitted diseases in Fukuoka, Kyushu, Japan.

The authors investigated the prevalence of antibody to hepatitis C virus (anti-HCV) in 404 female prostitutes, 428 clinic patients with a history of at least one episode of sexually transmitted disease, and 8,944 blood donors who served as the controls. All subjects were Japanese, and all studies were carried out in Fukuoka, Kyushu, Japan, in 1989. The prevalence of anti-HCV was significantly higher in the prostitutes (6.2%), in the female patients with sexually transmitted diseases (6.1%), and in the male patients with sexually transmitted diseases (2.9%) than in the controls (1.5%). Prevalence of anti-HCV increased with age in prostitutes and in the controls. The prevalence of anti-HCV in those who had been involved in prostitution for 1 year or more (8.1%) was higher than in those who had been involved in prostitution for less than 1 year (1.4%), but the difference was not statistically significant. One of the 152 anti-HCV negative prostitutes seroconverted between 1 and 2 years later. Among the subjects with sexually transmitted diseases, patients with a history of at least one episode of syphilis had a significantly higher prevalence of anti-HCV (4.4%) than the controls. Patients with acute urethritis and cervicitis also showed a high prevalence of anti-HCV (3.6% and 6.7%, respectively). These data support the possibility of sexual transmission of hepatitis C virus.

Adolescent↗
PubMed1992

In situ DNA-protein binding: a novel method for detecting DNA-binding activity of transcription factor in brain.

A novel method, in situ DNA-protein binding (in situ DPB), was developed to detect the distribution and DNA-binding activity of AP-1 and Sp1 binding proteins in situ. The regional distribution of AP-1 binding protein in mouse brain was different from that of Sp1. Antibody against the DNA-binding domain of Jun protein markedly reduced the AP-1 but not the Sp1 binding activity. The binding activity of AP-1 probe increased markedly in the brain after administration of methamphetamine. These results suggest that the in situ DPB is convenient and sensitive for detecting the distribution and the DNA-binding activity of transcription factors in situ.

Animals↗
PubMed1992

Synthesis and biological properties of 2-substituted myo-inositol 1,4,5-trisphosphate analogues directed toward affinity chromatography and photoaffinity labeling.

A series of myo-inositol 1,4,5-trisphosphate analogues with the 2-acyl substituents p-aminobenzoyl (7), p-azidobenzoyl (8), 4-(5-[2-(benzamido)ethyl]-2-hydroxyphenylazo)benzoyl (9), and cis,trans-4-aminocyclohexylcarbonyl (10) were synthesised and examined for their effects on the 5-phosphatase, the 3-kinase, the tritiated trisphosphate-binding activity, and the Ca(2+)-releasing activity. Each analogue inhibited the hydrolysis of D-[5-32P]Ins(1,4,5)P3 and the phosphorylation of D-[3H]Ins(1,4,5)P3, catalysed by erythrocyte ghosts and brain cytosol, respectively. The analogues acted as full agonists in releasing Ca2+ from permeabilised cells and also inhibited the binding of D-[3H]Ins(1,4,5)P3 to cerebellum microsomes. The analogues 7 and 10 were utilised for immobilisation of the trisphosphate on Sepharose and the subsequent affinity chromatography effected purification of the above proteins. A photoaffinity probe, the appendage of which acted as the photoaffinity probe as well as a non-radioactive molecular marker, was also derived from the analogue 7.

Animals↗
PubMed1992

Pyrogenic action of endothelin in conscious rabbit.

Injection of 0.3 nmol/kg endothelin(ET)-1 into the ear vein of conscious rabbits induced a significant increase in body temperature. ETB receptor specific agonist, namely 4-Ala-ET-1, also caused an elevation of the body temperature in a dose-dependent manner by injection into the ear vein of rabbit. These results suggest that ET play important roles in regulation of body temperature through selective stimulation of ETB receptor.

Analysis of Variance↗
PubMed1992

Mouse thromboxane A2 receptor: cDNA cloning, expression and northern blot analysis.

A cDNA clone for the mouse thromboxane A2 receptor was isolated from mouse lung cDNA library. The cDNA has a 1,023 base pair open reading frame which encodes a protein of 341 amino acid residues. STA2 and U-46619 induced inward current in Xenopus laevis oocytes injected with the transcript of the clone. Specific binding of [3H]S-145 was found in membranes of COS-1 cells transfected with the cDNA (Kd = 3.3 nM) and was displaced with unlabeled prostaglandins and thromboxane analogues in the order of S-145 greater than STA2 greater than U-46619 greater than PGD2 greater than PGF2 alpha = PGE2. Northern blot analysis demonstrated that thromboxane A2 receptor mRNA is expressed abundantly in thymus, spleen and lung.

Amino Acid Sequence↗
PubMed1992

Putative inositol 1,4,5-trisphosphate binding proteins in rat brain cytosol.

In previous works, we synthesized a series of inositol 1,4,5-trisphosphate (Ins(1,4,5)P3) analogs, with a substituent on the second carbon of the inositol ring. Using these analogs, the Ins(1,4,5)P3 affinity media were also synthesized (Hirata, M., Watanabe, Y., Ishimatsu, T., Yanaga, F., Koga, T., and Ozaki, S. (1990) Biochem. Biophys. Res. Commun. 168, 379-386). When the cytosol fraction from the rat brain was applied to an Ins(1,4,5)P3 affinity column, an eluate with a 2 M NaCl solution was found to have remarkable Ins(1,4,5)P3-binding activity. The active fraction was further fractionated with gel filtration chromatography, and two proteins with an apparent molecular mass of 130 or 85 kDa were found to be Ins(1,4,5)P3-binding proteins but with no Ins(1,4,5)P3 metabolizing activities. Partial amino acid sequences determined after proteolysis and reversed-phase chromatography revealed that the protein with an apparent molecular mass of 85 kDa is the delta-isozyme of phospholipase C and that of 130 kDa has no sequence the same as the Ins(1,4,5)P3-recognizing proteins hitherto examined. Ins(1,4,5)P3 at concentrations greater than 1 microM strongly inhibited 85-kDa phospholipase C delta activity, without changing its dependence on the concentrations of free Ca2+ and H+. Among inositol phosphates examined, Ins(3,4,5,6)P4 inhibited the binding of [3H]Ins(1,4,5)P3 to the 130-kDa protein at much the same concentrations as seen with Ins(1,4,5)P3. This report seems to be the first evidence for the presence of soluble Ins(1,4,5)P3-binding proteins in the rat brain, one of which is the delta isozyme of phospholipase C.

Amino Acid Sequence↗
PubMed1992

Signal transduction by tumor necrosis factor alpha is mediated through a guanine nucleotide-binding protein in osteoblast-like cell line, MC3T3-E1.

Transmembrane signalling mechanisms of tumor necrosis factor alpha (TNF alpha) were examined with special reference to the involvement of G-protein, in intact and permeabilized murine osteoblast-like cells. TNF alpha stimulated the release of 3H radioactivity from intact cells labeled with [3H]arachidonic acid within 10 min in a dose dependent manner and the production of lyso forms of phospholipids, an event presumably mediated through the activation of phospholipase A2. Production of cAMP and inositol 1,4,5-trisphosphate was not affected by TNF alpha. Pretreatment of the cells with pertussis toxin inhibited the liberation of [3H]arachidonate. GTP gamma S (guanosine 5'-3-O-(thio)triphosphate) reduced the binding affinity of [125I]TNF alpha to beta-escin-permeabilized cells. The addition of TNF alpha together with an unhydrolyzable analog of GTP, GTP gamma S, to the beta-escin-permeabilized cells prelabeled with [3H]arachidonic acid led to a release of the 3H radioactivity. The production of prostaglandin E2 (PGE2) was markedly stimulated by TNF alpha in a dose over 100 ng/ml, with a latent time of about 3 h, and the stimulation was abolished by pretreatment with pertussis toxin. The time and dose requirements for this process differed from those for the possible activation of phospholipase A2, thereby indicating that other process(es) in addition to the activation of phospholipase A2 may be responsible for the enhanced production of PGE2. The activity of cyclooxygenase (i.e. the combined activities of prostaglandin endoperoxide syntase and PGH2-PGE2 isomerase) was stimulated by TNF alpha with much the same time and dose requirements as for the production of PGE2, and the activation was found to be due to the increased amount of the enzyme, as assessed by a Western blot analysis with anti-cyclooxygenase antibody. This process was also sensitive to pertussis toxin. Therefore, receptors for TNF alpha in MC3T3-E1 cells apparently couple to G-protein sensitive to pertussis toxin and the coupling regulates the activations of phospholipase A2 and the de novo synthesis of cyclooxygenase.

1-Methyl-3-isobutylxanthine↗
PubMed1992

Characterization of immunoreactive endothelin in human urine.

We developed three antibodies, specific and sensitive to endothelin-1 (ET-1), and established two sandwich and three competitive enzyme immunoassays (EIAs). By using these EIAs, large immunoreactive ET (IR-ET) of molecular weight 10 k Da was identified as a main component of IR-ETs in human urine. This large IR-ET, which reacted with two antibodies specific for N-terminal region of ET-1 but not with the antibody against C-terminal peptide of ET-1, was partially purified by six-step procedure and examined by Western blotting after SDS polyacrylamide gel electrophoresis. The large IR-ET was detected as a single band at molecular weight of 10 k Da both in reduced and non-reduced conditions. From these results, the large IR-ET was thought to consist of a single polypeptide chain and possess the steric restricted N-terminal region of ET-1.

Amino Acid Sequence↗
PubMed1992

A cross-sectional study on the brainstem auditory evoked potential among workers exposed to carbon disulfide.

In order to clarify the chronic effect of carbon disulfide (CS2) on the central nervous system (CNS), the brainstem auditory evoked potential (BAEP) was measured in spinning workers exposed to CS2 in a viscose rayon manufacturing factory and unexposed workers in Japan. Workers exposed to CS2 were divided into three groups according to length of exposure: current spinning workers with an exposure duration of more than 240 months (L group, n = 34), current spinning workers with an exposure duration of 24-84 months (S group, n = 25), and former spinning workers with an exposure duration of more than 120 months (R group, n = 16). Unexposed controls were selected from workers in a nylon filament factory using the same criteria (N group; n = 40). BAEP records were analyzed based on the latencies of three main components (I, III, V) and interpeak latencies (I-III IPL, III-V IPL, I-V IPL). Latencies of component V, III-V IPL, and I-V IPL in the L group were significantly greater (P < 0.01, P < 0.05, P < 0.05, respectively). The significantly, higher III-V IPL in the L group suggested that in humans, chronic exposure to CS2 involves the auditory ascending tract in the brainstem. Recovery from this neurotoxic effect is apparently possible, as the BAEP parameters in the R group were not significantly higher than those of the N group despite the long previous CS2 exposure of the R group.

Adult↗
PubMed1992

Changes in auditory brainstem response in rats chronically exposed to carbon disulfide.

The chronic effect of carbon disulfide (CS2) on the central nervous system (CNS) was studied by examining auditory brainstem responses (ABRs) in female rats (Jcl Wistar) exposed to 200 ppm or 800 ppm CS2 by inhalation, 6 h a day, 5 days a week, for 15 weeks. Two modes of ABRs evoked by clicks at 61 and 96 dB sound pressure levels (61 dB-ABR and 96 dB-ABR) were recorded during the exposure and for 6 weeks afterwards. Three main components (I, III and V) of ABRs were analyzed from the latencies and differences between latencies of them (interpeak latencies, IPL I-III, IPL III-V and IPL I-V). The latencies of the three components and IPLs of 96 dB-ABR in rats group exposed to 800 ppm of CS2 were significantly delayed during the exposure period. The delay of latency of component V and IPL III-V and I-V tended to increase with exposure time. At 61 dB-ABR, the changes in the latency of component V, IPL III-V and I-V resembled those at 96 dB-ABR. For the rats group exposed to 200 ppm CS2, the latency of component I, IPL III-V and I-V at 96 dB-ABR were delayed significantly but transiently during the exposure period. For both groups, recovery from the latencies of the three components and IPLs of ABR was observed by the end of the recovery period. The delayed latencies of ABR observed in rats exposed to 800 ppm CS2 suggested a conduction dysfunction in the brainstem due to CS2 exposure.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Hepatitis C virus detection is facilitated by the combined use of c100 protein and GOR epitope.

Assay for the antibody to the c100 protein (anti-c100) lacks sensitivity in terms of detection of hepatitis C virus (HCV) in all samples. The author used anti-c100 and antibody to the GOR epitope (anti-GOR) by the enzyme-linked immunosorbent assay to examine 524 patients with chronic liver disease and 682 volunteer blood donors in Fukuoka, Japan. The prevalence of HCV infection, as revealed by the presence of anti-c100 and/or anti-GOR, was 3.9% in 540 volunteer blood donors, 12.7% in 142 volunteers with abnormal liver function, 7.4% in 135 patients with HBsAg-positive liver disease and 89.5% in 389 patients with non-A, non-B (NANB) liver disease. These results show a higher prevalence than demonstrated only by the anti-c100 in NANB liver disease patients (82.5%, P < 0.01). The concurrence of anti-c100 and anti-GOR in subjects with HCV infection was 23.8% in 21 volunteer blood donors, 44.4% in 18 volunteers with abnormal liver function and 61.2% in 348 NANB liver disease patients. The concurrence seems to increase with deterioration of liver function. We concluded that combination assay for anti-c100 and anti-GOR demonstrated a more accurate prevalence of HCV infection than single assay for anti-c100 among NANB liver disease patients, and that the presence of anti-GOR plays a role in liver disease in anti-HCV-positive subjects.

Adolescent↗
PubMed1992

Effect of left ventricular systolic pressure increase on ventricular arrhythmogenicity in old canine myocardial infarction.

OBJECTIVE: The aim was to examine the effect of an increase in left ventricular systolic pressure (LVSP) on ventricular arrhythmogenicity in old canine myocardial infarction. METHODS: Fourteen mongrel dogs of either sex weighing 11 to 15 kg were used. Studies were performed 28 d after creation of myocardial infarction by ligation of the anterior descending coronary artery. Electrical induction of ventricular arrhythmia and determinations of effective refractory period (ERP) and local intraventricular conduction delay (LIVCD) were performed using the extrastimulus technique with a cycle length of 300 ms in the normal and infarcted zones of the left ventricle. Heterogeneity of ERP (delta ERP) was determined as a difference between the longest and shortest ERP values in each site. LVSP was raised by constriction of the ascending aorta in a stepwise fashion (control, level A, level B). RESULTS: Incidence of electrically induced ventricular arrhythmia was increased from 28.6% at control level of LVSP [130.7(SEM 7.3) mm Hg] to 42.9% at level A [190.9(6.0) mm Hg] and to 64.3% (p < 0.05) at level B [243.3(4.0) mm Hg]. delta ERP and LIVCD were greater in the infarct zone than in the normal zone at each level of LVSP (p < 0.001). delta ERP in the infarct zone increased from 18.9(4.3) ms at control level of LVSP to 20.7(6.8) ms at level A, and to 27.1(8.1) ms at level B (p < 0.001). LIVCD in the infarct zone also increased from 22.9(6.2) ms at control level of LVSP to 26.8(4.9) ms at level A (p < 0.001), and to 36.1(6.0) ms at level B (p < 0.001). delta ERP and LIVCD in the normal zone were only slightly raised by increasing the LVSP. delta ERP and LIVCD in the infarct zone were closely correlated with incidence of electrically induced ventricular arrhythmia. CONCLUSIONS: Increasing the LVSP enhances ventricular arrhythmogenicity and pre-existing electrophysiologic abnormalities of the heart in the presence of old myocardial infarction. Thus a rise in LVSP from any cause in the old myocardial infarction can be a trigger of life threatening ventricular arrhythmias.

Animals↗
PubMed1992

Decreased hypothalamic and medullary GABA turnover in spontaneously hypertensive rats.

OBJECTIVE: The aim was to assess whether Gamma-aminobutyric acid (GABA) neurone activities in the central nervous system, especially in the hypothalamus and medulla oblangata, are altered in hypertension. METHODS: Central GABA content and turnover rate were measured in spontaneously hypertensive rats (SHR) and their normotensive Wistar Kyoto controls (WKY). GABA content was determined with high performance liquid chromatography, and in vivo GABA turnover rates were estimated by GABA accumulation after injection of amino-oxyacetic acid, a selective inhibitor of GABA degrading system. Two groups of nine week old male rats (32 SHR and 32 WKY) were used. RESULTS: GABA concentrations in cerebrospinal fluid were lower in SHR than in WKY. Since hypothalamus and medulla oblongata are the possible active sites of this system, basal GABA contents and in vivo GABA turnover rates were measured in hypothalamus and medulla oblongata. Basal GABA content in the medulla oblongata and hypothalamus was almost equal in SHR and WKY. On the other hand, GABA turnover rates were significantly lower in SHR than in WKY in both the hypothalamus and the medulla. CONCLUSIONS: Since it is known that GABA is an inhibitory neurotransmitter in the central nervous system and that it controls autonomic and cardiovascular activities, the findings suggest that the decreased hypothalamic and medullary GABAergic activities may permit sympathetic hyperactivity to contribute to the increase in blood pressure in SHR.

Aminooxyacetic Acid↗
PubMed1992

The effects of breastfeeding and presence of antibody to p40tax protein of human T cell lymphotropic virus type-I on mother to child transmission.

We examined the effects of various factors, including duration of breastfeeding, the status of mother's anti-p40tax, and titre of mother's anti-human T cell lymphototropic virus type-I (HTLV-I) on mother to child transmission of HTLV-I in 76 HTLV-I carrier mothers and 175 of their children. The overall prevalence of anti-HTLV-I among children was 16.0%. The prevalence of anti-HTLV-I among children breastfed for over 3 months was significantly higher (27.6%) than that of those breastfed for under 3 months (5.1%; P = 0.012). Of the 78 bottle-fed children, 10 (12.8%) were positive for anti-HTLV-I. In the children breastfed for over 3 months, the prevalence of anti-HTLV-I among 37 children of anti-p40tax positive mothers was 37.8% and that of 21 children of anti-p40tax negative mothers was 9.5%, a significant difference (P = 0.044). These data suggest that about 13% of bottle-fed children born to carrier mothers are infected with HTLV-I by routes other than breast milk, and that the mother's anti-p40tax can serve as a marker of infectivity of HTLV-I in the case of breastfeeding for over 3 months.

Adolescent↗
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

The expression of thromboxane A2 synthase and thromboxane A2 receptor gene in human uterus.

The expression of thromboxane (TX) A2 synthase and thromboxane A2 receptor gene in human uterus was investigated by immunoblotting, immunocytochemistry, Northern blot, in situ hybridization, and autoradiographic analyses. Human uterus contains a single immunoreactive protein of 55 kDa that corresponds to the molecular size of human TXA2 synthase. Human uterus also contains a single 2.8-kb TXA2 receptor mRNA transcript and a receptor protein that can bind TXA2 antagonist, 125I-PTA-OH. The immunoreactive TXA2 synthase, TXA2 receptor mRNA, and protein are present in endometrial glands, stromal cells, myometrial smooth muscle, and uterine blood vessels. The TXA2 synthase and TXA2 receptors in different uterine cells varied within as well as between various reproductive states. There were differences in the binding site numbers even between elongated and circular myometrial smooth muscle in all reproductive states except postmenopause. In summary, the data presented demonstrate for the first time that different human endometrial and myometrial cells and uterine blood vessels express TXA2 synthase as well as TXA2 receptor gene. The expression, as well as changes during various reproductive states, suggests that TXA2 could be an autocrine/paracrine regulator of human myometrial contractions, endometrial secretory functions, and intrauterine blood flow and could play a role in the initiation and/or progression of labor in women.

Autoradiography↗
PubMed1992

Effect of bilateral stellectomy on electrical instability of the atrium in the dog with hypokalemia.

To investigate the effect of sympathetic nerve activity on electrical instability of the atrium in the presence of hypokalemia, open chest electrophysiological study was performed before and after bilateral stellectomy (BS) in 15 dogs with hypokalemia (hypokalemia group) and in 15 dogs with normokalemia (control group). Hypokalemia was created by infusion of 5.0 g/kg of polystyrene sulfonic acid calcium into the colon. Serum level of potassium was significantly lower in the hypokalemia group (2.94 +/- 0.52 mEq/L) than in the control group (4.86 +/- 0.51 mEq/L, P less than 0.01) before BS. There was no significant change in serum level of potassium in the two groups after BS. Incidence of electrically induced atrial fibrillation (AF) was significantly higher in the hypokalemia group (80%) than in the control group (13%, P less than 0.001) before BS. It was significantly reduced in the hypokalemia group (40%, P less than 0.05), but not in the control group (6%) after BS. Dispersion of effective refractory period of the atrium (delta ERP) was significantly greater in the hypokalemia group (26.1 +/- 2.8 msec) than in the control group (22.0 +/- 3.3 msec, P less than 0.005) before BS. It was significantly decreased to 23.1 +/- 3.2 msec in the hypokalemia group (P less than 0.001) and to 20.6 +/- 2.5 msec in the control group (P less than 0.01) after BS. Maximum conduction delay in the atrium (MaxCD) was 36.1 +/- 3.5 msec before and 36.2 +/- 4.1 msec after BS in the hypokalemia group and 31.1 +/- 4.2 msec before and 32.3 +/- 4.9 msec after BS in the control group. There was a significant difference in MaxCD between the two groups before BS. Atrial fibrillation threshold (AFT) was significantly lower in the hypokalemia group (3.9 +/- 0.7 mA) than in the control group (13.8 +/- 3.1 mA, P less than 0.001) before BS. It was significantly increased both in the hypokalemia group (6.5 +/- 1.3 mA, P less than 0.001) and in the control group (15.0 +/- 2.7 mA, P less than 0.005) after BS. It is concluded that sympathetic nerve activity may play some role in the increase in electrical instability of the atrium in the presence of hypokalemia.

Animals↗