Search PubMed⌕ Search

Biomedical subjects

H Hirata

Publications and source records attributed to H Hirata.

At least 73 records · Page 4Linked to original sources
PubMed1998

Superoxide radicals are mediators of the effects of methamphetamine on Zif268 (Egr-1, NGFI-A) in the brain: evidence from using CuZn superoxide dismutase transgenic mice.

Administration of methamphetamine (METH) to mammals is known to cause deleterious effects to brain monoaminergic systems. These toxic effects are thought to be due to oxidative stress. Acute administration of METH causes activation of immediate-early genes (IEGs) such as c-fos and Zif268 mRNA in rodent brains. However, the exact mechanisms involved in these changes have not been completely clarified. As a first step towards assessing a possible role for free radicals in METH-induced changes in IEGs, we have used CuZn superoxide dismutase (SOD) transgenic (Tg) mice and have quantified the effects of METH on c-fos and Zif268 mRNAs by in situ hybridization techniques. Mice were injected with 25 mg/kg of METH and sacrificed at various time points afterwards. There were significant METH-induced increases in both c-fos and Zif268 mRNAs in the frontal cortex and striatum of both strains of animals. Interestingly, the increases in Zif268 were markedly attenuated in the CuZn SOD-Tg mice; the increases in c-fos were also attenuated, but to a significantly lesser degree. These results indicate that superoxide radicals might play an important role in the activation of Zif268 after METH administration. Because IEGs are modulators of gene expression, these results also raise the possibility that oxidative mechanisms might be important factors in neuroadaptive changes caused by stimulant drugs.

Animals↗
PubMed1998

Effects of toxic doses of methamphetamine (METH) on dopamine D1 receptors in the mouse brain.

Methamphetamine (METH) is a drug of abuse that causes marked DA depletion in the mammalian dopaminergic systems. These are characterized by marked decreases in presynaptic markers including dopamine (DA) levels and DA transporters. Very little research has been carried out to evaluate possible postsynaptic effects of this drug. In the present study, we assessed the status of METH on striatal DA D1 receptors labeled with [3H]SCH23390 after toxic doses of METH that were shown to cause marked depletion of various markers of presynaptic DA systems in mice [J. Neurochem. 69 (1997) 780]. Our results show that these doses of METH caused 30% decrease in striatal DA D1 receptors. In contrast, p53 knockout mice that show protection against the toxic effects of METH show no significant decreases in DA D1 receptors. These results suggest that toxic doses of METH that cause loss of presynaptic DA markers might also affect postsynaptic elements. We discuss the possibility that these changes might be secondary to toxic effects of METH on intrinsic striatal cell bodies.

Animals↗
PubMed1998

Transcriptional activation of the mouse HSP47 gene in mouse osteoblast MC3T3-E1 cells by TGF-beta 1.

HSP47 is a 47-kDa collagen-binding heat shock protein, the expression of which is always correlated with that of collagens in various cell lines. We examined the effects of TGF-beta 1, which is reported to induce the collagen genes, on the expression of HSP47 in mouse osteoblast MC3T3-E1 cells. Treatment of the cells with 5 ng/ml TGF-beta 1 for 24 h increased the level of HSP47 mRNA three-fold. Dose-dependent induction by TGF-beta 1 was observed for both HSP47 mRNA and collagen alpha 1 (I) mRNA, and actinomycin D inhibited this increase of HSP47 mRNA. To elucidate the TGF-beta 1 responsive element(s) in the mouse HSP47 gene, we generated a series of 5'-deletion promoters fused to luciferase reporter constructs. Transient transfection assays showed that TGF-beta 1 induced 4-6 fold the promoter activity of a region approximately -5.5 kbp upstream of the HSP47 gene. Two upstream regions, -3.9 to -2.7 kbp and -280 to -50 bp were shown to be involved in the activation in response to TGF-beta 1 treatment.

3T3 Cells↗
PubMed1998

Caspases are activated in a branched protease cascade and control distinct downstream processes in Fas-induced apoptosis.

Two novel synthetic tetrapeptides, VEID-CHO and DMQD-CHO, could selectively inhibit caspase-6 and caspase-3, respectively. We used these inhibitors to dissect the pathway of caspase activation in Fas-stimulated Jurkat cells and identify the roles of each active caspase in apoptotic processes. Affinity labeling techniques revealed a branched protease cascade in which caspase-8 activates caspase-3 and -7, and caspase-3, in turn, activates caspase-6. Both caspase-6 and -3 have major roles in nuclear apoptosis. Caspase-6 cleaves nuclear mitotic apparatus protein (NuMA) and mediates the shrinkage and fragmentation of nuclei. Caspase-3 cleaves NuMA at sites distinct from caspase-6, and mediates DNA fragmentation and chromatin condensation. It is also involved in extranuclear apoptotic events: cleavage of PAK2, formation of apoptotic bodies, and exposure of phosphatidylserine on the cell surface. In contrast, a caspase(s) distinct from caspase-3 or -6 mediates the disruption of mitochondrial membrane potential (permeability transition) and the shrinkage of cytoplasm. These findings demonstrate that caspases are organized in a protease cascade, and that each activated caspase plays a distinct role(s) in the execution of Fas-induced cell death.

Antigens, Nuclear↗
PubMed1998

Replacements of single basic amino acids in the pleckstrin homology domain of phospholipase C-delta1 alter the ligand binding, phospholipase activity, and interaction with the plasma membrane.

The pleckstrin homology (PH) domain of phosphatidylinositol-specific phospholipase C-delta1 (PLC-delta1) binds to both D-myo-inositol 1,4, 5-trisphosphate (Ins(1,4,5)P3) and phosphatidylinositol 4, 5-bisphosphate (PtdIns(4,5)P2) with high affinities. We have previously identified a region rich in basic amino acids within the PH domain critical for ligand binding (Yagisawa, H., Hirata, M., Kanematsu, T., Watanabe, Y., Ozaki, S., Sakuma, K., Tanaka, H., Yabuta, N., Kamata, H., Hirata, H., and Nojima, H. (1994) J. Biol. Chem. 269, 20179-20188; Hirata, M., Kanematsu, T., Sakuma, K., Koga, T., Watanabe, Y., Ozaki, S., and Yagisawa, H. (1994) Biochem. Biophys. Res. Commun. 205, 1563-1571). To investigate the role of these basic residues, we have performed site-directed mutagenesis replacing each of the basic amino acid in the N-terminal 60 residues of PLC-delta1 (Lys24, Lys30, Lys32, Arg37, Arg38, Arg40, Lys43, Lys49, Arg56, Lys57, and Arg60) with a neutral or an acidic amino acid. The effects of these mutations on the PH domain ligand binding properties and their consequence for substrate hydrolysis and membrane interactions of PLC-delta1 were analyzed using several assay systems. Analysis of [3H]-Ins(1,4,5)P3 binding, measurement of the binding affinities, and measurements of phospholipase activity using PtdIns(4,5)P2-containing phospholipid vesicles, demonstrated that residues Lys30, Lys32, Arg37, Arg38, Arg40, and Lys57 were required for these PLC-delta1 functions; in comparison, other mutations resulted in a moderate reduction. A subset of selected mutations was further analyzed for the enzyme activity toward substrate present in cellular membranes of permeabilized cells and for interaction with the plasma membrane after microinjection. These experiments demonstrated that mutations affecting ligand binding and PtdIns(4,5)P2 hydrolysis in phospholipid vesicles also resulted in reduction in the hydrolysis of cellular polyphosphoinositides and loss of membrane attachment. All residues (with the exception of the K43E substitution) found to be critical for the analyzed PLC-delta1 functions are present at the surface of the PH domain shown to contain the Ins(1,4,5)P3 binding pocket.

Amino Acid Sequence↗
PubMed1998

Melatonin attenuates methamphetamine-induced toxic effects on dopamine and serotonin terminals in mouse brain.

Methamphetamine (METH) is a drug of abuse that causes deleterious effects to brain monoaminergic systems. These toxic effects are thought to be due to oxidative stress. The pineal hormone, melatonin, has been shown to have neuroprotective effects against toxic quinones and oxidative stress produced by catecholamines. The present study was thus undertaken to assess possible protective effects of melatonin against METH-induced neurotoxic effects on the striatum and the nucleus accumbens by using autoradiographic techniques. Four dosages (5, 20, 40, 80 mg/kg) of melatonin were administered to mice intraperitoneally 30 minutes prior to the injections of METH (4 x 5 mg/kg) given at 2-hour intervals. The lowest doses of melatonin (5 mg/kg) had no significant effects against METH-induced toxicity. However, the higher doses (40 or 80 mg/kg) of melatonin significantly attenuated METH-induced toxic effects on both dopamine and serotonin systems. These data provide further evidence for a possible role of oxidative stress in METH-induced toxicity.

Animals↗
PubMed1998

Preservation of the knee joint in limb salvage of osteosarcoma in the proximal tibia. A case report.

A 12-year-old boy with osteosarcoma in the proximal tibia underwent a successful limb-saving operation with preservation of the epiphyseal and articular cartilage of the proximal tibia as a result of his remarkable response to chemotherapy. There was no evidence of tumour invasion to the adjacent physis, as demonstrated by image findings. The bone defect was reconstructed using autoclaved autogeneous bone with a vascularized fibula. The patient exhibits excellent function of the affected limb, and the knee joint remains disease-free 55 months postoperatively.

Bone Neoplasms↗
PubMed1998

Attenuation of 6-hydroxydopamine-induced dopaminergic nigrostriatal lesions in superoxide dismutase transgenic mice.

6-Hydroxydopamine is a neurotoxin that produces degeneration of the nigrostriatal dopaminergic pathway in rodents. Its toxicity is thought to involve the generation of superoxide anion secondary to its autoxidation. To examine the effects of the overexpression of Cu,Zn-superoxide dismutase activity on 6-hydroxydopamine-induced dopaminergic neuronal damage, we have measured the effects of 6-hydroxydopamine on striatal and nigral dopamine transporters and nigral tyrosine hydroxylase-immunoreactive neurons in Cu,Zn-superoxide dismutase transgenic mice. Intracerebroventricular injection of 6-hydroxydopamine (50 microg) in non-transgenic mice produced reductions in the size of striatal area and an enlargement of the cerebral ventricle on both sides of the brains of mice killed two weeks after the injection. In addition, 6-hydroxydopamine caused marked decreases in striatal and nigral [125I]RTI-121-labelled dopamine transporters not only on the injected side but also on the non-injected side of non-transgenic mice; this was associated with decreased cell number and size of tyrosine hydroxylase-immunoreactive dopamine neurons in the substantia nigra pars compacta on both sides in these mice. In contrast, superoxide dismutase transgenic mice were protected against these neurotoxic effects of 6-hydroxydopamine, with the homozygous transgenic mice showing almost complete protection. These results provide further support for a role of superoxide anion in the toxic effects of 6-hydroxydopamine. They also provide further evidence that reactive oxygen species may be the main determining factors in the neurodegenerative effects of catecholamines.

Animals↗
PubMed1998

Differentiation and apoptosis without DNA fragmentation in cultured Schwann cells derived from wallerian-degenerated nerve.

The Schwann cell cables provide particularly favorable sites for the growth of regenerating axonal sprouts. However, if they remain denervated, endoneurial fibrosis takes place with the Schwann cells atrophying and total Schwann cell number gradually decrease with time. Even when regenerating axonal sprouts invade into the cables, Schwann cells do not survive for long periods if they fail to make axonal contact. These observations strongly suggest the involvement of apoptosis in peripheral nerve degeneration and regeneration. So, we investigated the behavior of Schwann cells prepared from wallerian-degenerated adult rat sciatic nerve in vitro. The secondary cultured Schwann cells showed serial changes in morphology, mitotic activity and migratory activity as they do during Schwann cell cable formation in vivo. At the final stage of differentiation, the Schwann cells became rounded and detached from the flask with extensive blebbing. Electron micrographs clearly demonstrated typical cytoplasmic changes of apoptosis, but, nuclei of most of the cells retained their size and morphology with residual nucleolar structures. An agarose gel electrophoresis of DNA clearly demonstrated that there was not any DNA fragmentation up to 120 h after detachment. Results by in situ apoptosis detection assay did not show any DNA degradation despite the substantial decrease in Schwann cell number. In conclusion, during peripheral nerve degeneration and regeneration, supernumerary Schwann cells are removed by apoptosis, however, it lacks most of the nuclear events of usual apoptosis.

Journal Article↗
PubMed1998

Opposing effects of low and high molecular weight kininogens on cell adhesion.

High molecular weight kininogen (HK) blocks cell spreading but not cell attachment to surfaces coated with vitronectin and other ligands of beta3 integrins. We sought to learn the structural basis of this phenomenon. Monoclonal antibodies against the histidine-rich D5 domain in the light chain of 2-chain HK abolished the inhibitory effect of 2-chain HK on spreading of MG-63 osteosarcoma cells on vitronectin-coated tissue-culture plastic. The antibodies were effective only if incubated with 2-chain HK in solution and did not abolish the anti-cell-spreading effect of 2-chain HK that was pre-adsorbed to tissue-culture plastic. Exposure of an epitope in the histidine-rich domain was less when HK was adsorbed to tissue-culture plastic (oxidized polystyrene) than when it was adsorbed to ELISA plastic (untreated polystyrene). Loss of the epitope correlated with increased anti-cell-spreading activity of HK on tissue-culture plastic. The light chain of 2-chain HK containing D5 and that containing recombinant D5 both had anti-cell-spreading activity, but only when present in solution during adhesion assays. Pre-adsorption of recombinant D5 to tissue-culture plastic resulted in a surface on which adsorbed 2-chain HK had little anti-cell-spreading activity. Binding study revealed that HKa bound to immobilized vitronectin. The histidine-rich D5 domain of light chain of HK was identified as one of the binding sites of vitronectin, suggesting that the masking of the RGD cell-binding site of immobilized vitronectin is the molecular mechanism of anti-cell-spreading effect of HKa. In contrast, low molecular weight kininogen (LK), which lacks D5, augmented cell spreading on vitronectin-coated tissue-culture plastic. Thus, HK and LK have opposing effects on VN-dependent cell adhesion. The augmenting effect of LK was greater if LK was preincubated with cells or adsorbed to the surface at pH>7.0. Analysis of fragments of LK and antibody inhibition studies localized the cell-adhesion activity to the D3 domain that is common to LK and HK. These findings indicate that the D5 domain mediates the adsorption of HK or 2-chain HK to vitronectin substratum in anti-adhesive conformations, i.e., masking of the RGD cell-binding site of vitronectin. Such conformers inhibit cell spreading on vitronectin even though a cell-adhesion site is present in D3.

Antibodies, Monoclonal↗
PubMed1998

Effective irradiation of a metastatic region of the lung in a patient with extraskeletal myxoid chondrosarcoma.

Complete obstruction of the right main bronchus occurred in a 76-year-old woman due to pulmonary metastasis from the extraskeletal myxoid chondrosarcoma (EMC) which had been detected 5 years earlier. Treatment with Nd-YAG laser and biopsy forceps opened up the lumen of the right main bronchus 90%, and then X-irradiation was given toward the remaining tumor. The tumor disappeared almost completely following radiotherapy and such a state had lasted for several years until she died of old age at the age of 81. We judged that radiotherapy had been effective for this tumor. To date, the information concerning the effect of radiotherapy on this disease is insufficient.

Aged↗
PubMed1998

A new anti-MRSA antibiotic complex, WAP-8294A. I. Taxonomy, isolation and biological activities.

WAP-8294A, produced by Lysobacter sp., is a complex consisting of water soluble depsipeptide antibiotics. It was further purified by column chromatographies and HPLC, and 19 components were obtained. WAP-8294A2, a major component, and minor components A1, A4, Ax8, Ax9 and Ax13 were active against gram-positive bacteria, in particular, methicillin-resistant Staphylococcus aureus (MRSA) in vitro. WAP-8294A2 was highly active in vivo in mice against the systemic infection of MRSA.

Animals↗
PubMed1998

[Successful treatment with donor leukocyte transfusion followed by interferon-alpha in a patient with relapsed chronic myelogenous leukemia after allogeneic bone marrow transplantation].

A 44-year-old man with CML in chronic phase was admitted for BMT from an HLA-identical sibling. Ph positive cells were undetectable at 3 and 7 months after BMT but became detectable by cytogenetic analysis of bone marrow aspirates at 12 months after BMT. He was treated with IFN-alpha (6 million units/day, 3 times a week) without apparent effect. Donor leukocyte transfusion (DLT) was performed four times between 20 months and 23 months after BMT, transfusing 3.4 x 10(8) mononuclear cells/kg. However, leukocytosis appeared and the NAP score declined at 25 months after BMT. FISH analysis revealed an increase in bcr-abl positive cells. IFN-alpha was restarted using the same schedule at 26 months after BMT. Three months after restarting IFN-alpha, the leukocyte count fell to the normal range, NAP score increased to a normal level, and bcr-abl positive cells decreased markedly. He has remained in hematological and cytogenetic remission for 20 months, and bcr-abl chimeric mRNA remained undetectable by PCR. These results suggest that CML which does not respond to DLT may be cured by subsequent IFN-alpha therapy, possibly by inducing anti-leukemia immune responses.

Adult↗
PubMed1997

Differential toxic effects of methamphetamine (METH) and methylenedioxymethamphetamine (MDMA) in multidrug-resistant (mdr1a) knockout mice.

The toxic effects of methamphetamine (METH) (2.5, 5.0 and 10.0 mg/kg) and methylenedioxymethamphetamine (MDMA) (5.0, 10.0 and 20.0 mg/kg) on dopaminergic systems were assessed in the striatum and of the nucleus accumbens in mdr1a wild-type and knockout mice. METH caused significant dose-dependent decreases of dopamine (DA) and DA transporters (DAT) in the striatum and the nucleus accumbens (NAc) of both wild-type and knockout mice. The lowest doses of METH (2.5 mg/kg) caused only small changes in the wild-type, but marked. decreases in the mdr1a knockout mice. The two higher doses (5 mg/kg and 10 mg/kg) caused similar changes in both strains of mice. In contrast to METH, MDMA caused greater percentage decreases in DAT in the wild-type mice. For example, the lowest dose (5 mg/kg) caused significant decreases in DAT in the NAc of wild-type but not of mdr1a knockout mice. The highest dose (20 mg/kg) caused similar changes in both the strains. These results suggest that METH and MDMA interact differentially with P-glycoproteins. These observations document, for the first time, a role for these proteins in the entry of METH and MDMA into the brain via the blood-brain barrier, with P-glycoprotein possibly facilitating the entry of MDMA but interfering with that of METH into the brain.

Animals↗
PubMed1997

Methamphetamine-induced serotonin neurotoxicity is attenuated in p53-knockout mice.

Methamphetamine (METH) is a drug of abuse that causes deleterious effects to brain monoaminergic systems. The tumor suppressor gene, p53, is thought to play an important role in cell death. In the present study, we have assessed the participation of p53 in METH-induced serotonergic neurotoxicity, by using the mice lacking the gene for p53 protein. Three dosages (2.5, 5.0 and 10.0 mg/kg x 4) of METH were administered to wild-type (p53+/+), heterozygous (p53+/-) and homozygous (p53-/-) p53-knockout mice. The two lower doses caused no significant changes in serotonin (5-HT) transporters in any of the groups. The highest dose (10.0 mg/kg) caused significant decreases in striatal 5-HT transporters in wild-type (-31%) and heterozygous (-18%) mice. In contrast, 5-HT transporters were not significantly decreased in homozygous mice. These results suggest that the tumor suppressor, p53, plays an important role in METH-induced serotonergic neurotoxicity in mice brain. These data provide further evidence for a role of p53 in the neurotoxic effects of METH.

Analysis of Variance↗
PubMed1997

A possible immunosuppressant, cycloprodigiosin hydrochloride, obtained from Pseudoalteromonas denitrificans.

Cycloprodigiosin hydrochloride (cPrG.HCl), a member of the prodigiosin family, is a red pigment obtained from the marine bacterium Pseudoalteromonas denitrificans. cPrG.HCl markedly suppressed 3H-thymidine incorporation by concanavalin A stimulated murine splenocytes but had little effect on lipopolysaccharide dependent 3H-thymidine incorporation, indicating that cPrG.HCl acts as a selective inhibitor of T cell proliferation in the same way as other members of the prodigiosin family. cPrG.HCl inhibited the proliferation of the PMA stimulated Jurkat cells through an apoptotic process. Intriguingly, cPrG.HCl inhibited the H+ translocation by vacuolar type ATPase in chromaffin granule membranes without any effect on either its ATPase activity nor on the membrane conductance of phospholipid bilayers, suggesting that cPrG.HCl selectively uncouples H+ translocation from the ATPase reaction rather than acting as a non-specific ionophore. Since crystalline cPrG.HCl is highly stable, it raises the possibility of its therapeutic use as an immunosuppressant.

Animals↗
PubMed1997

Local opiate withdrawal in locus coeruleus in vivo.

Hyperactivity of noradrenergic locus coeruleus (LC) neurons following withdrawal from chronic opiates has been implicated in the opiate withdrawal syndrome. Here, we report that local withdrawal induced in vivo by microinfusion of an opiate antagonist into the LC of morphine-dependent rats marginally, but significantly, activated LC neurons above the level obtained with local naloxone microinfusion in naive rats. This local withdrawal response contributes a significant fraction (approximately 19%) of the total LC hyperactivity induced by systemic naloxone.

Animals↗