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Biomedical subjects

T Nishikawa

Publications and source records attributed to T Nishikawa.

At least 343 records · Page 19Linked to original sources
PubMed1997

Identification of S100b protein as copper-binding protein and its suppression of copper-induced cell damage.

We have isolated from bovine brain a protein with a high capacity to inhibit the copper ion-catalyzed oxidation of L-ascorbate and identified it as S100b protein, an EF-hand calcium-binding protein, by sequencing its proteolytic peptides. Copper binding studies showed that this protein has four copper-binding sites per dimeric protein molecule with a dissociation constant of 0.46 microM and that in the presence of L-ascorbate, copper ions bind to a total of six binding sites with a great increase in affinity. Furthermore, we examined whether S100b protein can prevent copper-induced cell damage. Bovine S100b protein was found to suppress dose-dependently the hemolysis of mouse erythrocytes induced by CuCl2. We transformed Escherichia coli cells with pGEX-5X-3 vector containing a cDNA for rat S100b protein, so that this protein could be expressed as a fusion protein with glutathione S-transferase. The transformed cells were demonstrated to be markedly resistant to a treatment with CuCl2 plus H2O2 as compared with the control cells expressing glutathione S-transferase alone. These results indicate that S100b protein does suppress oxidative cell damage by sequestering copper ions.

Amino Acid Sequence↗
PubMed1997

Characterization of autoantibodies in pemphigus using antigen-specific enzyme-linked immunosorbent assays with baculovirus-expressed recombinant desmogleins.

Pemphigus vulgaris (PV) and pemphigus foliaceus (PF) are autoimmune skin diseases caused by autoantibodies against desmoglein (Dsg) 3 and Dsg1, respectively. Routine immunofluorescence testing of skin and serum from patients cannot distinguish between these two severe diseases since both have IgG Abs directed against keratinocyte cell surfaces. In this study, recombinant Dsg3 and Dsg1, produced as secreted proteins by baculovirus expression, have been utilized to develop ELISAs for the specific characterization of their autoantibodies. Of 49 PV sera, 46 were positive in the Dsg3 ELISA and 44 of 46 PF sera were positive in the Dsg1 ELISA, compared with only 3 of 23 sera of bullous pemphigoid, and none of 53 normal control sera in both ELISAs. Both the Dsg3 and Dsg1 ELISAs were more specific and sensitive than conventional immunofluorescence staining. These Ag-specific ELISAs revealed that more than one-half of PV sera (26 of 49) had anti-Dsg1 Abs in addition to anti-Dsg3 Abs. PV patients who had not only oral mucous lesions but also significant skin involvement tended to have higher titers of anti-Dsg1 Abs. Furthermore, the ELISA reactivity correlated well with clinical disease activity in 5 of 6 PV and 5 of 5 PF patients. This ELISA provides a sensitive and highly specific assay for the diagnosis of patients with PV and PF, the correlation of disease activity with serum Ab levels, and a novel tool for investigating the immunopathogenesis of pemphigus.

Autoantibodies↗
PubMed1997

Effects of ketamine on dopamine metabolism during anesthesia in discrete brain regions in mice: comparison with the effects during the recovery and subanesthetic phases.

The effects of ketamine on the levels of dopamine (DA), norepinephrine (NE), 5-hydroxytryptamine (5-HT, serotonin) and their metabolites were examined in discrete brain regions in mice. A high dose of ketamine (150 mg/kg, i.p.) did not change DA metabolism in the frontal cortex, nucleus accumbens, striatum and hippocampus, but did decrease it in the brainstem during anesthesia. In contrast, during recovery from the ketamine anesthesia, the high dose increased the level of homovanillic acid (HVA) in all brain regions. A low subanesthetic dose of ketamine (30 mg/kg, i.p.) increased the concentrations of both 3,4-dihydroxyphenylacetic acid (DOPAC) and HVA only in the nucleus accumbens. The DA level was not affected by any ketamine treatment. During ketamine anesthesia, the content of 3-methoxy-4-hydroxy-phenylglycol (MHPG) was decreased in the brainstem, whereas during recovery from anesthesia, the MHPG level was increased in the frontal cortex, nucleus accumbens and brainstem. The NE content was not altered in any region by ketamine treatment. The concentration of 5-hydroxyindoleacetic acid (5-HIAA) was reduced in the frontal cortex, striatum, hippocampus and brainstem during ketamine anesthesia. The 5-HT level was unaltered in all regions except the brainstem where it was reduced. In contrast, after anesthesia, the concentrations of both 5-HT and 5-HIAA were increased in the striatum. During the subanesthetic phase, however, the levels of NE, 5-HT and their metabolites were unchanged. These neurochemical results are consistent with the electrophysiological findings that a high dose of ketamine does not change the basal firing rates of nigrostriatal DA neurons during anesthesia, while low subanesthetic doses significantly increase those of ventral tegmental DA neurons.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1997

Uncompetitive inhibition of [3H]1,3-di-o-tolyl-guanidine-defined sigma binding sites by desipramine, propranolol and alprenolol in rat brain.

Desipramine, imipramine, clomipramine, (-)-propranolol, (-)-alprenolol, (+/-)-pentazocine and risperidone caused a concentration-dependent inhibition of 6 nM [3H]DTG (1,3-di-o-tolylguanidine)-defined sigma (sigma) binding with Ki values of about 0.5-2.5 microM in well-washed homogenates obtained from rat cerebral cortex. The saturation studies revealed that the inhibition by desipramine (1-4 microM), (-)-propranolol (1 microM) and (-)-alprenolol (3 microM) resulted from a reduction of the Bmax value without alteration of the Kd of [3H]DTG binding to the cortex or hippocampus. In contrast, imipramine, (+/-)-pentazocine, clomipramine and risperidone competitively attenuated the cortical or hippocampal [3H]DTG binding. These findings demonstrate the uncompetitive inhibition of [3H]DTG binding by neuroactive drugs, thereby providing further support for the possible multiple regulation of cerebral sigma receptors.

Adrenergic beta-Antagonists↗
PubMed1997

Epilepsy and exacerbation of brain injury in mice lacking the glutamate transporter GLT-1.

Extracellular levels of the excitatory neurotransmitter glutamate in the nervous system are maintained by transporters that actively remove glutamate from the extracellular space. Homozygous mice deficient in GLT-1, a widely distributed astrocytic glutamate transporter, show lethal spontaneous seizures and increased susceptibility to acute cortical injury. These effects can be attributed to elevated levels of residual glutamate in the brains of these mice.

ATP-Binding Cassette Transporters↗
PubMed1997

Abnormal distribution of neurofilament L in neurons with Alzheimer's disease.

Abnormality of cytoskeletal proteins is closely related to the pathology of Alzheimer's disease. As neurofilament proteins are major cytoskeletal components of neurons, abnormality of neurofilaments is proposed in brain with Alzheimer's disease. Free-floating sections of the hippocampus with Alzheimer's disease were studied immunohistochemically, using a polyclonal antibody specifically bound to the tail region of neurofilament L (NF-L). In brains with early onset type of Alzheimer's disease, many neurons and dystrophic neurites were labeled by the antibody, while these observations were not seen in either brains with late onset type or control brains. Double immunohistochemical staining of NF-L and tau protein demonstrated that abnormal deposition of NF-L was not always accompanied with that of tau protein, indicating that the abnormal deposition of NF-L might not occur in parallel with that of tau protein. These observations suggest the involvement of neurofilament proteins on the pathology of Alzheimer's disease in a different way than tau protein.

Aged↗
PubMed1997

Absence of human T-lymphotropic virus type I in Japanese patients with cutaneous T-cell lymphoma.

Cutaneous T-cell lymphoma (CTCL) is a disease entity characterized by a primary sporadic T-cell proliferation in the skin. Human T-lymphotropic virus type 1 (HTLV-1) is a retrovirus that causes adult T-cell leukemia/lymphoma. Recently, several authors have detected the HTLV-1 genome in genomic DNA from patients with CTCL and proposed a causal relation of HTLV-1 to CTCL. However, it remains controversial because these studies contain some problems in materials used to detect HTLV-1. We investigated both fresh and cultured T lymphocytes (128 specimens) derived from 50 Japanese patients with CTCL, where HTLV-1 is endemic, by using polymerase chain reaction with four sets of primers including gag, pol, env, and pX regions of HTLV-1 to elucidate the relationship between HTLV-1 and CTCL in Japan. However, none of the 128 DNA specimens revealed positive for HTLV-1 in contrast to the previous studies. We conclude that CTCL, which does not include HTLV-1, is present although the pathogenesis of CTCL may be different by areas or races.

Adult↗
PubMed1997

Depletion of cerebral D-serine in non-ketotic hyperglycinemia: possible involvement of glycine cleavage system in control of endogenous D-serine.

Tissue concentrations of D-serine and other chiral and non-chiral amino acids were measured post-mortem in the cerebral cortex of the neonatal or infantile individuals with (three cases) or without (seven cases) non-ketotic hyperglycinemia (NKH) using high performance liquid chromatography with fluorometric detection. In the cortical tissues of the NKH patients lacking activity of glycine cleavage system, there was a marked reduction and elevation of the contents of D-serine and glycine, respectively, compared to non-NKH controls. Systemic administration of an inhibitor of glycine cleavage system (GCS), cysteamine, mimicked the changes in the cortical concentrations of these amino acids in the 8-day-old rats. Augmentation of brain glycine levels by means of intraperitoneal injection of glycine itself resulted in an increase in cortical D-serine contents in the neonatal rats with normal activity of GCS. These findings provide the first evidence that GCS might be implicated in the biosynthesis or content regulation of endogenous D-serine in the mammalian brain.

Amino Acid Oxidoreductases↗
PubMed1997

Nitric oxide contributes to the progression of myocardial damage in experimental autoimmune myocarditis in rats.

BACKGROUND: Excess amounts of NO produced by an inducible NO synthase (iNOS) in response to cytokines may be cytotoxic and can be destructive to tissue. We investigated the role of NO in the development of myocardial damage and the effects of aminoguanidine (AG), an inhibitor of iNOS, on experimental autoimmune myocarditis in rats. METHODS AND RESULTS: Autoimmune myocarditis was induced in 20 Lewis rats by injection of porcine cardiac myosin. Ten of the 20 rats were administered AG. The severity of myocarditis was evaluated by measuring the size of myocarditic lesion and serum levels of CK-MB. Serum NO levels were determined using the Cd/Cu method. Tissue specimens were immunohistochemically examined for iNOS and nitrotyrosine. Histopathological study revealed extensive myocardial destruction and massive inflammatory cell infiltration in AG-untreated rats but only focal mononuclear cell infiltration in AG-treated rats. The mean percent areas of inflammatory lesions in the untreated and treated rats were 56 +/- 13% and 3 +/- 2%, respectively (P < .001). NO levels were 102 +/- 23 and 25 +/- 9 IU/L, respectively (P < .01). CK-MB levels were 68 +/- 13 and 16 +/- 13 nmol/L, respectively (P < .01). Superoxide production as measured with an ex vivo monitoring system was also significantly decreased in the treated rats. Nitrotyrosine relating to the generation of peroxynitrite was detected through immunostaining in the inflammatory lesions of untreated rats but not in those of treated rats. CONCLUSIONS: Excess amounts of NO produced by iNOS appear to contribute to the progression of myocardial damage in myocarditis. AG may prove to be useful in the treatment of myocarditis.

Animals↗
PubMed1997

Anti-HTLV-1 antibody positive cutaneous T-cell lymphoma.

BACKGROUND: Adult T-cell leukemia/lymphoma (ATLL) is a neoplasm of the mature helper T-lymphocyte. Human T-lymphotropic virus type 1 (HTLV-1) has been shown to be the cause of this neoplasm. Recently, however, the HTLV-1 genome has been found in some patients with cutaneous T-cell lymphoma (CTCL), which suggests a causal relation of HTLV-1 to CTCL. Thus, the relation between the HTLV-1 genome and CTCL, as well as the difference between ATLL and CTCL, have come into question. METHODS: The authors examined two patients with CTCL whose serum anti-HTLV-1 antibodies were constantly positive. The Southern blot technique, inverse polymerase chain reaction (IPCR), and polymerase chain reaction (PCR) with four sets of primers for gag, pol, env, and pX regions of HTLV-1 were used to clarify the distinctions between ATLL and CTCL. RESULTS: Clinically, one patient presented with multiple subcutaneous nodules with involvements of the internal organ, and the other patient was typical for mycosis fungoides. No integration of HTLV-1 DNA was detected by IPCR or the Southern blot technique in either patient. PCRs with the four sets of primers were all found to be positive for HTLV-1 except one. CONCLUSIONS: The authors conclude that ATLL should be differentiated from CTCL in view of the responsibility of HTLV-1 for promoting or maintaining CTCL.

Antigens, CD↗
PubMed1997

Evidence for N-methyl-D-aspartate receptor-mediated increase in norepinephrine utilization in the prefrontal cortex of unanesthetized rats.

Local injection of N-methyl-D-aspartate (NMDA; 10-20 nmol/rat) into the prefrontal cortex of conscious rats caused a dose-related and an NMDA antagonist-reversible facilitation of norepinephrine (NE) disappearance in the cortical region during 35 min after inhibition of tyrosine hydroxylase. Destruction of ascending NE neurons by bilateral application of 6-hydroxydopamine into the superior cerebellar peduncle failed to affect [3H]N-(1-[2-thienyl]cyclohexyl)piperidine binding to the NMDA receptor-associated ion channel in the prefrontal cortex. These results indicate that, under unanesthetized conditions, the prefrontal NE neurons may be under glutamatergic facilitatory control mediated by the NMDA receptors which are located on the non-NE systems in the frontal cortex.

2-Amino-5-phosphonovalerate↗
PubMed1997

Oral clonidine premedication decreases energy expenditure in human volunteers.

PURPOSE: Clonidine not only stops postoperative shivering and decreases oxygen consumption, but also decreases energy expenditure with or without a reduction in shivering during recovery from anaesthesia. It is important to see if clonidine decreases energy expenditure at rest since this may contribute to a postoperative decrease in energy expenditure. The authors tested the hypothesis that oral clonidine decreases energy expenditure at rest. METHODS: Twenty healthy male volunteers were randomly assigned to one of two groups. Ten volunteers received oral clonidine approximately 5 micrograms.kg-1 (clonidine group), while the remaining 10 volunteers received placebo (control group). Blood pressure, heart rate, body temperature at the tympanic membrane, sedation score graded from 1 (alert) to 5 (sleeping and difficult to be aroused by tactile stimulation) were measured before and at 30-min intervals for three hours after administration of clonidine or placebo. Measurements of energy expenditure and respiratory quotient were made with a head canopy system at one-minute intervals and averaged over 15 min before, and at 30, 60, 90, 120, and 180 min after administration of clonidine or placebo. RESULTS: Sedation score increased from 1 to 3 (median) after clonidine administration. Energy expenditure decreased from 1452 +/- 225 kcal.24hr-1 (mean +/- SD) at baseline to 1258 +/- 175 kcal.24hr-1 at 180 min after clonidine administration (P < 0.05). CONCLUSION: This study suggests that oral clonidine at a dose of 5 micrograms.kg-1 decreases energy expenditure at rest.

Administration, Oral↗
PubMed1997

Involvement of the alpha2-adrenergic system in polydipsia in schizophrenic patients: a pilot study.

Animal studies have suggested the involvement of the adrenergic system in drinking behavior. The present study investigated the involvement of the alpha2-adrenergic system in the polydipsia of patients with chronic schizophrenia by use of an alpha2 agonist and an antagonist. Four patients with schizophrenic disorders accompanied by intermittent hyponatremia and polydipsia were the subjects of, and completed, this study. Drinking behavior was assessed by calculating the percent of maximum weight gain [PMWG: (maximum diurnal weight - standard weight) x 100/standard weight]. Standard weight was defined as body weight after 8 h of water restriction. Clonidine (75, 150, and 225 mg/day) increased the PMWG in a dose-dependent manner in the four subjects. In contrast, in three of the subjects, mianserin (30, 60, and 90 mg/day) decreased PMWG, and the severe polydipsia disappeared almost completely. These findings indicate clearly that the alpha2-adrenergic system is involved in the drinking behavior of schizophrenic patients. Mianserin appears to be clinically useful in treating such patients with polydipsia.

Adrenergic alpha-Agonists↗
PubMed1997

Expression of the retinoid-inducible polypeptide, midkine, in human epidermal keratinocytes.

Midkine (MK) is a retinoid-inducible and potent cell growth/differentiation factor active during mouse embryogenesis. We studied MK expression in various cell strains established from the skin. MK and its mRNA were detected in cultured keratinocytes but not in melanoma cell lines or dermal fibroblasts by both Western blot analysis and reverse transcription-polymerase chain reaction (RT-PCR). Treatment of cultured keratinocytes with retinoic acid (10(-5) M, 24 h) resulted in an increase in the level of MK mRNA. When added to cultured keratinocytes, MK stimulated cell proliferation fourfold. Immunohistochemistry revealed MK to be present at the epidermal-dermal junction in embryonic mouse skin and in normal human skin. The limited expression of MK in epidermal keratinocytes indicates that this polypeptide may be involved in the differentiation/proliferation of keratinocytes.

Animals↗
PubMed1997

Human beta-migrating very low density lipoprotein induces foam cell formation in human mesangial cells.

To elucidate the mechanism of foam cell formation in the mesangial region of a kidney observed in a familial type III hyperlipoproteinemic patient presenting with diabetes mellitus and nephrotic syndrome, we have examined, in the present study, the effect of human beta-VLDL (apo E2/E2) on foam cell formation in human mesangial cells, since an increase in beta-VLDL is a characteristic feature of this patient. Human beta-VLDL (apo E2/E2) induced foam cell formation in human mesangial cells. The binding of [125I]LDL to human mesangial cells was inhibited completely by both LDL and beta-VLDL. On the other hand, the binding of [125I]beta-VLDL was completely inhibited by beta-VLDL, but partially by LDL. The LDL receptor, but not the VLDL receptor was down-regulated by accumulation of cholesteryl esters. These results suggest that human beta-VLDL (apo E2/E2)-induced foam cell formation in mesangial cells is mediated through both the LDL receptor pathway and the beta-VLDL specific pathway, in which the VLDL receptor is one of the candidates.

Blotting, Northern↗
PubMed1997

Proliferation of smooth muscle cells in acute allograft vascular rejection.

OBJECTIVES: To determine whether immune injury during acute cardiac rejection induces phenotypic modulation of arterial smooth muscle cells and lesion formation, we studied the expression of embryonic myosin heavy-chain isoform and degrees of intimal proliferation in aortas and coronary arteries of allografted rabbit hearts. Modulation of phenotype in arterial smooth muscle cells during acute vascular injury is a widely reported phenomenon, and proliferation and migration of medial smooth muscle cells contribute to development of intimal hyperplasia of arteries in response to immune injury. METHODS: Rabbit hearts were heterotopically transplanted to the neck without immunosuppression. Hearts were harvested at 2, 5, 7, and 10 days after transplantation. Proliferation of smooth muscle cells was assessed by bromodeoxyuridine labeling. Staining for immunohistochemical indicators was done with use of monoclonal antibodies that recognize T lymphocytes and all types of smooth muscle cells (SM1), adult type of smooth muscle cells (SM2), and embryonic myosin heavy-chain isoform. Intimal thickening and luminal narrowing were assessed with a computer-assisted video image analysis system. RESULTS: Intimal thickening and luminal narrowing in aortas and coronary arteries gradually increased in a time-dependent manner. The neointima thus formed consisted of proliferating smooth muscle cells positive for both SM1 and embryonic myosin heavy-chain isoform and massive T lymphocyte accumulation. Intimal proliferation was more prominent in aortas and large epicardial coronary arteries than in the intramyocardial small coronary arteries. CONCLUSIONS: These findings suggest that allogeneic immune injury facilitates phenotypic modulation of smooth muscle cells, which may contribute to subsequent transplantation-associated atherosclerosis.

Animals↗