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Biomedical subjects

H Nakagawa

Publications and source records attributed to H Nakagawa.

At least 19 recordsLinked to original sources
PubMed1992

Circadian variation of [3H]dopamine handling in adrenal chromaffin cells of mice.

Circadian variation of exogenous [3H]dopamine handling by adrenal chromaffin cells was examined using mice habituated to 08.00-20.00 h light cycle. Experiments were carried out at 00.00, 06.00, 12.00 and 18.00 h. [3H]Dopamine-derived radioactivity reached a peak at 2 min then decreased rapidly except at 18.00 h, when no particular peak was observed at 2 min but at 30 min in both intact and denervated adrenals. In intact adrenals, the 2-min peak at 06.00 h was suppressed by corticosterone while in denervated adrenals the 2-min peak remained. The present result indicates that quick turnover of [3H]dopamine was suppressed by a steroid surge at about 2 h before light to dark alteration. Normal innervation is necessary for corticosterone-induced suppression.

Adrenal Glands↗
PubMed1992

Inactivation of substance P by granulation tissue-derived gelatinase.

An active gelatinase has been purified from the conditioned medium of granulation tissue culture formed by carrageenin injection in rats. The purified gelatinase gave a single band corresponding to a M(r) of 57 kDa on both sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and SDS-gelatin PAGE. The granulation tissue-derived gelatinase selectively cleaved the Gln6-Phe7 bond of substance P (SP) with a Km of 0.17 mM and a Vmax of 0.027 nmol SP7-11/min/micrograms protein, resulting in the generation of biologically inactive fragments, SP1-6 and SP7-11. Our data suggest that the gelatinase produced by granulation tissue participates in the inactivation of SP in the inflammatory site.

Animals↗
PubMed1992

Inhibition of nicotinic acetylcholine receptor-mediated secretion and synthesis of catecholamines by sea urchin toxin in cultured bovine adrenal medullary cells.

We previously reported the partial purification and characterization of a toxic substance (sea urchin toxin) isolated from the pedicellariae of the sea urchin Toxopneustes pileolus (Nakagawa and Kimura, Jpn J Pharmacol 32: 966-968, 1982). In the present study, we examined the effect of sea urchin toxin on catecholamine secretion and synthesis in cultured bovine adrenal medullary cells. Sea urchin toxin inhibited the secretion of catecholamines stimulated by carbachol and nicotine but not by veratridine or a high concentration of K+. The toxin inhibited the carbachol-evoked influx of 22Na+ and 45Ca2+ at concentrations similar to those for catecholamine secretion. The inhibition of catecholamine secretion by sea urchin toxin was not overcome by increasing the concentration of carbachol. Preincubation of cells with the toxin caused a time-dependent inhibition in the secretion stimulated by carbachol even when the toxin was removed from the incubation medium. The toxin suppressed catecholamine synthesis and tyrosine hydroxylase activity in carbachol-stimulated cells. In addition, sea urchin toxin inhibited [3H]phencyclidine binding to adrenal medullary cells whereas it did not alter cyclic GMP accumulation caused by muscarine. Further purified fractions from sea urchin toxin by concanavalin A affinity column chromatography also inhibited carbachol-evoked secretion of catecholamines. These results suggest that sea urchin toxin inhibits carbachol-enhanced secretion and synthesis of catecholamines by suppression of nicotinic acetylcholine receptor-mediated Na+ influx and subsequent Ca2+ influx in cultured adrenal medullary cells.

Adrenal Medulla↗
PubMed1992

Purification and initial characterization of the proteasome from the higher plant Spinacia oleracea.

The proteasome (multicatalytic protease complex), a high molecular weight protein complex, has been purified from spinach leaves by successive chromatography on DEAE-cellulose, Bio-Gel A-1.5m, DEAE-TOYOPEARL 650C, and DEAE-5PW. The molecular mass was estimated to be 850 kDa by gel filtration. Polyacrylamide gel electrophoresis of the proteasome gave a single protein band under nondenaturing conditions and at least 10 bands in the range of 21-32 kDa in the presence of sodium dodecyl sulfate. By electron microscopy after negative staining with uranyl acetate, the proteasome from spinach appeared as symmetrical ring-shaped particles. The substrate specificity of proteasomes indicates that they contain at least three types of activity, namely, chymotrypsin-like, Staphylococcus aureus V8 protease-like, and trypsin-like activities. The former two activities were enhanced by poly-L-lysine or sodium dodecyl sulfate. Moreover, we examined the immunological reactivities of proteasomes from various eukaryotes. As a result, cross-immunoreactivities of some subunits were observed. These properties of the proteasome are similar to those of proteasomes isolated from various other eukaryotic sources.

Amino Acid Sequence↗
PubMed1992

Effect of orbital enucleation on glucose homeostasis and morphology of the suprachiasmatic nucleus.

In rats there is a direct neural connection called the retinohypothalamic tract (RHT) from retinal ganglion cells to the ventrolateral part of the suprachiasmatic nucleus (SCN), which has neurons containing vasoactive intestinal polypeptide (VIP)-like substance. Previously, we observed that bilateral orbital enucleation (blinding) caused temporary suppression of the hyperglycemic response to intracranial injection of 2-deoxy-D-glucose (2DG) from week 4 to 6 after blinding. Moreover, bilateral lesions of the SCN had a similar effect. From these findings, we supposed that the neurons responsible for the hyperglycemic response to 2DG were present in the SCN, that after blinding these neurons temporarily lost their activity, and that this functional change was reflected in the morphology of the SCN. To investigate this possibility, we examined the morphological changes of the SCN by Nissl staining and immunohistochemical studies with anti-VIP and anti-peptide histidine isoleucine (PHI) antibodies in blinded rats, and the relationship between these morphological changes and the hyperglycemic response to 2DG. After surgical blinding, we observed following changes. (1) The optic chiasm became thinner. (2) The SCN became displaced rostrally. (3) The density of neurons in the middle to caudal part of the SCN, where the retinal ganglion cells projected, decreased markedly without change in cell number during the period when the hyperglycemic response to intracranial injection of 2DG was temporarily suppressed after blinding. The first and second changes seemed to reflect reduction of fibers and axon terminals of retinal ganglion cells and their innervation, respectively. As the third change was parallel with suppression of the hyperglycemic response to 2DG injection, it may reflect functional change of the neurons in the SCN that are responsible for the hyperglycemia due to 2DG.

Animals↗
PubMed1992

Differences between vasorelaxant responses of the canine and human mesenteric arteries and veins to amrinone.

Amrinone induced similar degrees of relaxation in human mesenteric arteries and veins contracted with KCl, but exerted a more potent vasodilator effect in canine mesenteric veins than in arteries. Dibutyryl cAMP had a stronger effect on KCl-induced contraction in canine mesenteric veins than in arteries. These results suggest that amrinone promotes a different vasodilating action in human and canine mesenteric vessels, possibly via different sensitivity to cAMP in each vascular smooth muscle.

Amrinone↗
PubMed1992

Molecular cloning and expression of chicken C-terminal Src kinase: lack of stable association with c-Src protein.

Cloning and sequencing of chicken C-terminal Src kinase (CSK), a tyrosine kinase that phosphorylates the regulatory C-terminal tyrosine residue present on cytoplasmic tyrosine kinases of the Src family, demonstrated a high degree of interspecies conservation as well as src homology 2 and 3 domains N-terminal to the kinase domain. The lack of autophosphorylation sites distinguishes CSK from other tyrosine kinases. CSK is unique and does not belong to a gene family, suggesting that it may phosphorylate other members of the Src family of tyrosine kinases in addition to c-Src. Since complex formation between c-Src and CSK seemed a likely regulatory step in the control of c-Src kinase activity, such an association was investigated by immunoprecipitation and Western blotting as well as intracellular localization studies. Although some portions of CSK were found in a membrane fraction, no complex formation between CSK and c-Src was observed, suggesting that the src homology 2 domain of CSK does not play a role in the direct interaction of c-Src.

Amino Acid Sequence↗
PubMed1992

Increase in nucleoside diphosphatase in rat brain striatum lesioned with kainic acid.

The activity of ammoniagenesis from guanine nucleotides was found to increase significantly in rat brain after infusion of kainic acid into the striatum. Among the enzymes involved in degrading guanine nucleotides, nucleoside diphosphatase was markedly increased in the lesioned striatum. The enzyme activity began to increase 2 days after the infusion, and reached the maximum on the 13th day, the level being 4 times as high as that of the intact contralateral region. The increased activity was due to Type L enzyme, judging from its substrate specificity. Puromycin and cycloheximide inhibited this increase, indicating that the increased activity resulted from an increase in the net synthesis of the enzyme. These findings suggest that Type L NDPase might play some important roles in gliosis after neuronal lesion.

Acid Anhydride Hydrolases↗
PubMed1992

Assignment of the human cytochrome P-450 nifedipine oxidase gene (CYP3A4) to chromosome 7 at band q22.1 by fluorescence in situ hybridization.

We have used a full length cDNA clone (2.2 kb) for the human cytochrome P-450 nifedipine oxidase (CYP3A4) enzyme as a probe to determine its chromosome localization by fluorescence in situ hybridization. CYP3A4 was mapped on R-banded human prometaphase chromosomes, and the precise localization of CYP3A4 on chromosome 7 was further confirmed by a delineation of G-banded pattern on the same prometaphase chromosomes through a combination of UV-filter. We assigned CYP3A4 to chromosome 7 at q22.1.

Cells, Cultured↗
PubMed1992

Gastrointestinal endoscopy in Henoch-Schönlein purpura.

Gastrointestinal (GI) endoscopy was performed in seven patients with Henoch-Schönlein purpura (HSP). In two patients there were no cutaneous lesions at the time of endoscopy, but inflammation of the duodenum, especially of the second part, led to suspicion of the disease. Upper GI endoscopy showed abnormalities in six of seven cases, and sigmoidoscopy in one of four cases. The changes were more marked in the second part of the duodenum rather than in the bulb or the stomach. The endoscopic findings included redness, swelling, petechiae or haemorrhage, erosions and ulceration of the mucosa. Histology of the mucosal biopsy specimens revealed non-specific inflammation with positive staining for IgA in the capillaries, but failed to show vasculitis. Upper GI endoscopy, including study of IgA, can be useful in the diagnosis of HSP. Colonoscopy is less helpful, especially if limited to the sigmoid colon.

Adolescent↗
PubMed1992

Arginine and lysine residues as NADH-binding sites in NADH-nitrate reductase from spinach.

Chemical modifications of spinach leaf nitrate reductase, and its 28,000 M(r) fragment with phenylglyoxal, 2,3-butanedione and pyridoxal phosphate reduce the catalytic activity of the enzyme. The kinetics of the modification indicate a rapid inactivation followed by a slower rate of inactivation. NADH-nitrate reductase, NADH-cytochrome c reductase and NADH-ferricyanide reductase activities of the nitrate reductase complex are inactivated at a faster rate when compared to the loss of FMNH2-nitrate reductase and reduced methyl viologen (MVH)-nitrate reductase activities. NADH protects the inactivation of NADH-ferricyanide reductase activity of the 28,000 M(r) fragment of nitrate reductase. These data suggest that nitrate reductase contains active sites of arginine and lysine residues that are involved in the NADH binding site of the enzyme.

Amino Acid Sequence↗
PubMed1992

Light enhances sympathetic and suppresses vagal outflows and lesions including the suprachiasmatic nucleus eliminate these changes in rats.

Neurons in the suprachiasmatic nucleus (SCN) are suggested to be involved in the mechanism of glucose homeostasis. This mechanism was examined by studies on the effect of illumination on the activity of autonomic efferents to the adrenals, pancreas and liver. Exposure of one eye of anesthetized rats to light enhanced the efferent activity of the adrenal nerve and suppressed that of vagal pancreatic and hepatic nerves. No change in efferent activities of these nerves was observed on light-stimulation of rats with lesions that included the bilateral SCN. These findings indicate that light signals modulate visceral functions including metabolic processes through the retinohypothalamic tract probably via the SCN to autonomic efferent pathways innervating visceral organs.

Adrenal Glands↗
PubMed1992

Detection of an i(17q) chromosome by fluorescent in situ hybridization with a chromosome 17 alpha satellite DNA probe.

An isochromosome for the long arm of chromosome 17,i(17q), is frequently found as an additional chromosome aberration to the Ph with advanced disease in the chronic myelocytic leukemia (CML). We studied an i(17q) in blood samples from two patients with CML in blast crisis with a biotinylated chromosome 17 specific alpha satellite deoxyribonucleic acid probe. G-banded karyotypes of these patients showed a dicentric i(17q), dic(17)(p11.2). Fluorescence in situ hybridization (FISH) delineated one normal chromosome 17 and one i(17q) among metaphase chromosomes; the latter showed a dicentric pattern. In most interphase nuclei of both patients, two fluorescence spots were observed. In some interphase nuclei, including mature neutrophils, the dicentric chromosome was discernible by its size and shape of the fluorescent spots. Three fluorescent spots were observed in a small proportion of interphase cells, and existence of a subclone with two normal chromosome 17 and an i(17q) was confirmed by examining a large number of metaphase plates. The results of FISH provided us with information of numerical and structural aberrations of chromosome 17 in interphase cells.

Blast Crisis↗
PubMed1992

Chemotactic factor in the pregnant rabbit uterine cervix.

OBJECTIVE: Neutrophil accumulation is one of the characteristic changes observed in uterine cervical stroma at term pregnancy, but chemotactic activity in the tissue is obscure. Our study examined the existence and production of chemotactic factor in the rabbit uterine cervix. STUDY DESIGN: Uterine cervical explants of rabbits at term pregnancy and nonpregnant rabbits were cultured with and without interleukin-1 alpha. Rat neutrophilic chemotaxis in culture media was evaluated with a Boyden chamber. RESULTS: Tissue extract from the pregnant rabbit uterine cervix at term pregnancy contained more chemoattractive activity than the nonpregnant cervix. Production of chemoattractant from cultured rabbit cervical explants at term pregnancy was also higher than that from nonpregnant explants. The addition of interleukin-1 alpha to the culture system promoted its production. This chemoattractant was characterized as a true chemotactic factor and heat-stable and trypsin-sensitive protein with an apparent relative molecular mass of 16,200. So far, these properties are very similar to those of the interleukin-8 family. Rabbit uterine cervical fibroblast is characterized as a chemotactic factor-producing cell in the rabbit uterine cervix. CONCLUSION: These results indicate that interleukin-8-like chemotactic factor participates in the cervical ripening at term pregnancy and that the production of this factor is controlled effectively by interleukin-1.

Animals↗
PubMed1992

Pathology of spinal cord lesions caused by ossification of the posterior longitudinal ligament, with special reference to reversibility of the spinal cord lesion.

This report describes pathological findings of the spinal cord damage, with ossification of the posterior longitudinal ligament (OPLL), with special reference to reversibility of such lesions. Twenty-five autopsy cases associated with OPLL were examined, and the spinal cord damage was pathologically classified into four categories based on degree of destruction (stage 0-3). In stage 0 and stage 1, major pathological changes in the gray matter and the degree of compression on the spinal cord were well correlated to deformity of the anterior horn. In stage 2 and stage 3, neurons were almost completely obliterated and necrosis with cavitation were frequently observed. Destruction of the spinal cord in stage 2 and stage 3 is considered to be irreversible; therefore, surgical treatment is recommended at stage 0 or stage 1.

Calcinosis↗
PubMed1992

Sleep propensity free-runs with the temperature, melatonin and cortisol rhythms in a totally blind person.

In previous studies, we found that many totally blind people have free-running melatonin rhythms, but that free-running melatonin rhythms were not necessarily associated with periodic insomnia and daytime sleepiness. Thus, it was not clear if the circadian sleep propensity rhythm was free-running with the other circadian rhythms. In the present study, we report that the sleep propensity rhythm (as defined by an ultrashort sleep-wake schedule) free-ran with the melatonin, temperature and cortisol rhythms in a 44-year-old totally blind man even though he maintained a conventional sleep schedule and did not complain of clinically significant insomnia or excessive daytime sleepiness.

Adult↗