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Biomedical subjects

H Wada

Publications and source records attributed to H Wada.

At least 901 records · Page 50Linked to original sources
PubMed1988

Induction of cytosolic aspartate aminotransferase by a high-protein diet.

Induction of cytosolic aspartate aminotransferase (glutamic oxaloacetic transaminase) was observed in rat liver on administration of a high-protein diet. The enzyme activity in the liver of rats given 60% and 80% protein diet increased to 1.8- and 1.9-fold that in the liver of rats maintained on 20% protein diet, with about 2-fold increases in the levels of functional sGOT mRNA, measured by in vitro translation. Whereas the activity of mitochondrial aspartate aminotransferase did not increase. Induction of cytosolic aspartate aminotransferase was also detected immunocytochemically.

Animals↗
PubMed1987

Different localization of receptors for omega-conotoxin and nitrendipine in rat brain.

The bindings of radioiodinated omega-conotoxin GVIA and [3H]-nitrendipine to subcellular fractions of rat brain were examined. The results indicated that omega-conotoxin binding site was mainly present in the mitochondrial fraction, whereas nitrendipine binding site was rich in the mitochondrial but also present in the post-mitochondrial fraction. Fractionation of the mitochondrial fraction on a sucrose density gradient centrifugation showed that the both binding sites were localized in the heavy synaptosomal fraction. These results strongly suggest that the N- and L-type voltage-sensitive calcium channels have different localizations.

Animals↗
PubMed1987

Effects of oral and intravenous administrations of dopamine and L-dopa on plasma levels of two isomers of dopamine sulfate in man.

The levels of two isomers of dopamine sulfate, dopamine-3-O-sulfate (DA3S) and dopamine-4-O-sulfate (DA4S), in human plasma were measured by HPLC-fluorometry. The basal plasma levels of DA3S and DA4S in the early morning were 13.8 +/- 1.9 and 3.2 +/- 0.5 pmoles/ml, respectively (means +/- S.E.M.). Oral administrations of dopamine (50 mg/body) and 1-dihydroxyphenylalanine (L-DOPA, 250 mg/body) increased the plasma levels of these dopamine sulfates almost 100-fold to 1807 +/- 266 and 1674 +/- 195 pmoles/ml of DA3S, and 466 +/- 83 and 321 +/- 76 pmoles/ml of DA4S. Intravenous dopamine infusion (5 micrograms/kg/min for 30 min) markedly increased the plasma free dopamine concentration, as expected, but increased the levels of DA3S and DA4S only slightly to 110 +/- 32 and 25 +/- 9 pmoles/ml, respectively. In contrast, intravenous L-DOPA (25 mg/body) resulted in a slight increase of free dopamine followed by marked increases of DA3S and DA4S to 691 +/- 219 and 139 +/- 40 pmoles/ml, respectively. These data indicate that O-sulfation of dopamine, especially 3-O-sulfation, is the main pathway for metabolism of intravenously and orally administered L-DOPA and orally ingested dopamine. This sulfation is suggested to occur in the gut wall.

Administration, Oral↗
PubMed1987

An antibody and anti-idiotypic antibody against the extra signal peptide of pre-aspartate aminotransferase.

A peptide (extra signal peptide) comprising amino acids 1-29 of pig liver pre-mitochondrial aspartate aminotransferase (p-mAAT) was synthesized chemically. The peptide was found to block the import of rat liver p-mAAT into rat liver mitochondria. An antibody raised against the peptide immunoprecipitated rat liver p-mAAT synthesized in a rabbit reticulocyte cell-free translation system. These results suggested that the extra signal peptide sequence of p-mAAT is essential for import of p-mAAT into the mitochondria and that there is structural homology between the extra signal peptides of pig and rat liver p-mAAT. An anti-idiotypic antibody against the peptide was also prepared and purified by affinity chromatography on an Affi-Gel 10 anti-peptide IgG column and was then characterized.

Animals↗
PubMed1987

Analysis of the kinetics of cyclic AMP hydrolysis by the cyclic GMP-stimulated cyclic nucleotide phosphodiesterase.

The kinetics of cAMP hydrolysis by the purified calf liver cGMP-stimulated cyclic nucleotide phosphodiesterase were analyzed in the absence or presence of a number of competitive inhibitors of the methylxanthine type according to a two-site competitive model for allosteric enzymes. Methylxanthines were also classified by graphical analysis of classical competition kinetics at saturating cAMP. This treatment yielded Km/KI ratios which estimated the relative effectiveness of the binding of substrate and inhibitors to the "high affinity" (ES complex) state without establishing individual equilibrium-binding constants of cAMP and inhibitors for specific enzyme states. Individual binding constants for substrate and inhibitors were estimated directly by fitting primary data to the rate equation for the two-site competitive model. The equilibrium dissociation constants for cAMP to the "high" (KS) and "low affinity" (AKS) states were 2.4 +/- 0.8 and 410 +/- 140 microM, respectively. Dissociation constants for various inhibitors to the high (BKI) and low affinity (KI) states were also estimated. The ratio KS/BKI, which directly compared the equilibrium-binding constants of substrate and inhibitors to the high affinity state (ES complex), was in excellent agreement with Km/KI ratios derived from graphical analysis. Whereas a number of the methylxanthine analogues were more effective or as effective as cAMP in binding to the low affinity or "ligand-free" state, only isobutylmethylxanthine was effective as cAMP in binding to the high affinity state (1-methyl-3-isopropylxanthine, and 1,3-dipropylxanthine were somewhat less effective). These findings suggested that allosteric transitions might alter the topography of specific hydrophobic domains at cyclic nucleotide-binding sites and that structural determinants were more stringent for binding to the high affinity state than to the low affinity state.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1987

Effects of pH on allosteric and catalytic properties of the guanosine cyclic 3',5'-phosphate stimulated cyclic nucleotide phosphodiesterase from calf liver.

We have investigated effects of pH on the catalytic and allosteric properties of the cGMP-stimulated cyclic nucleotide phosphodiesterase purified from calf liver. In the "activated" state, i.e., with 0.5 microM [3H]cAMP plus 1 microM cGMP or at saturating substrate concentrations (250 microM [3H]cAMP or [3H]cGMP), hydrolysis was maximal at pH 7.5-8.0 in assays of different pH. Hydrolysis of concentrations of substrate not sufficient to saturate regulatory sites and below the apparent Michaelis constant (Kmapp), i.e., 0.5 microM [3H]cAMP or 0.01 microM [3H]cGMP, was maximal at pH 9.5. Although hydrolysis of 0.5 microM [3H]cAMP increased with pH from 7.5 to 9.5, cGMP stimulation of cAMP hydrolysis decreased. As pH increased or decreased from 7.5, Hill coefficients (napp) and Vmax for cAMP decreased. Thus, assay pH affects both catalytic (Vmax) and allosteric (napp) properties. Enzyme was therefore incubated for 5 min at 30 degrees C in the presence of MgCl2 at various pHs before assay at pH 7.5. Prior exposure to different pHs from pH 6.5 to 10.0 did not alter the Vmax or cGMP-stimulated activity (assayed at pH 7.5). Incubation at high (9.0-10.0) pH did, in assays at pH 7.5, markedly increase hydrolysis of 0.5 microM [3H]cAMP and reduce Kmapp and napp. After incubation at pH 10, hydrolysis of 0.5 microM [3H]cAMP was maximally increased and was similar in the presence or absence of cGMP. Thus, after incubation at high pH, the phosphodiesterase acquires characteristics of the cGMP-stimulated form. Activation at high pH occurs at 30 degrees C but not 5 degrees C, requires MgCl2, and is prevented but not reversed by ethylenediaminetetraacetic acid.(ABSTRACT TRUNCATED AT 250 WORDS)

1-Methyl-3-isobutylxanthine↗
PubMed1987

The histaminergic innervation of the mesencephalic nucleus of the trigeminal nerve in rat brain: a light and electron microscopical study.

Histaminergic fibers in the mesencephalic nucleus of the trigeminal nerve of Long-Evans rats were examined by light and electron microscopy after peroxidase-antiperoxidase immunocytochemical staining for histidine decarboxylase (HDC) as a marker. By light microscopy, neurons in the mesencephalic nucleus of the trigeminal nerve were seen to be surrounded by a number of HDC-like immunoreactive (HDCI) fibers, suggesting the presence of axo-somatic contact. This finding was supported by immunoelectron microscopic demonstration of synaptic contact of some HDCI fibers with the soma of the neurons in this nucleus. These findings indicate that histamine is involved in the sensory regulation of movement of the masticatory muscles at the level of the trigeminal mesencephalic nucleus.

Animals↗
PubMed1987

En bloc immunohistochemistry reveals extensive distribution of histidine decarboxylase-immunoreactive neurons on the ventral surface of the rat hypothalamus.

En bloc immunohistochemistry was used to examine the distribution of L-histidine decarboxylase (HDC)-immunoreactive neurons on the ventral surface of the rat hypothalamus. Following standard paraformaldehyde fixation, the ventral hypothalamus containing the tuber cinereum was carefully dissected free and incubated en bloc with antisera to HDC followed by standard avidin-biotin complex immunohistochemistry. Microscopic examination of these en block preparations revealed the existence of an extensive plexus of HDC-immunoreactive neurons located directly upon the ventral hypothalamic surface. HDC-immunoreactive neurons were largely restricted to the caudal half of the hypothalamic surface, and were multipolar, with 2-5 dendrites radiating in all directions from the soma. The proximity of these neurons to the ventral surface of the brain suggests that histaminergic neurons might be capable of responding to cerebrospinal fluid borne substances. Thus, one form of input to hypothalamic histaminergic neurons may be humoral rather than synaptic.

Animals↗
PubMed1987

Demonstration of histaminergic neurons in horizontal cells of guinea pig retina.

The existence of L-histidine decarboxylase (HDC, EC 4.1.1.22)-like immunoreactive (HDC-I) cells in guinea pig retina was demonstrated using antiserum raised against HDC purified from fetal rat liver. The anti-HDC antiserum partially cross-reacted guinea pig L-DOPA decarboxylase (DDC, EC 4.1.1.28), so the histaminergic neurons were carefully identified. Comparison of HDC-I and DDC-like immunoreactive (DDC-I) cell types in adjacent sections revealed that HDC-I structures were found in some horizontal cells and amacrine cells, and double-staining procedures with anti-HDC antiserum and monoclonal anti-DDC antibody showed that HDC-I horizontal cells had no DDC-I structures, but all the HDC-I amacrine cells had DDC-I structures. From the results, some horizontal cells (with HDC-like immunoreactivities but without DDC-like immunoreactivities) were concluded to be histaminergic.

Animals↗
PubMed1987

Effects of temperature on allosteric and catalytic properties of the cGMP-stimulated cyclic nucleotide phosphodiesterase from calf liver.

We have investigated effects of temperature on the catalytic and allosteric properties of the cGMP-stimulated cyclic nucleotide phosphodiesterase from calf liver. Vmax for cAMP and cGMP increased as assay temperature increased from 5 to 45 degrees C. At substrate concentrations below Kmapp, however, hydrolysis increased as temperature decreased from 45 to 5 degrees C and was much greater at 5 degrees C than at 45 degrees C. As assay temperature decreased, Kmapp for cAMP and cGMP decreased. Hill coefficients for cAMP and cGMP were approximately 1.9 at 45 degrees C and 1.2-1.0 at 5 degrees C. cGMP stimulated hydrolysis of 0.5 microM [3H]cAMP at all assay temperatures. Although maximal activity stimulated by cGMP, like Vmax, was lowest at 5 degrees C, presumably because of the effect of temperature on catalytic activity, the apparent activation constant (K alpha app) for cGMP stimulation was lower at 5 degrees C than at 45 degrees C. Thus, affinity for both substrate and effector was increased at 5 degrees C, suggesting that low temperature promotes transitions of the cGMP-stimulated phosphodiesterase to a "high affinity" state. That cGMP stimulated cAMP hydrolysis at 5 degrees C suggests that temperature-induced transitions are incomplete and/or readily reversible. In assays at 30 degrees C competitive inhibitors, like substrates, induce allosteric transitions which result in enhanced hydrolysis of low substrate (1.0 microM [3H] cAMP) concentrations. At higher substrate concentrations (50 microM [3H]cAMP), with the enzyme in the "activated" state, inhibitors compete with substrate at catalytic sites and reduce hydrolysis. At 45 degrees C, as at 30 degrees C, 1-methyl-3-isobutylxanthine (IBMX) and papaverine increased hydrolysis of 1.0 microM [3H]cAMP and reduced hydrolysis of 50 microM [3H]cAMP. At 5 degrees C, however, IBMX and papaverine inhibited hydrolysis of both 1.0 and 50 microM [3H]cAMP. Enzyme activity was relatively more sensitive to inhibition by IBMX at 5 degrees C than at 45 degrees C. Taken together, these observations support the notion that low temperature induces incomplete or readily reversible transitions to the high affinity state for substrates, effectors, and inhibitors. These observed effects of temperature also point out that enzyme determinants and topographical features responsible for transitions to the high affinity state and expression of catalytic activity can be regulated independently.

1-Methyl-3-isobutylxanthine↗
PubMed1987

Immunocytochemical localizations of cytosolic and mitochondrial glutamic oxaloacetic transaminase isozymes in rat primary sensory neurons as a marker for the glutamate neuronal system.

The localization of cytosolic (s-) and mitochondrial (m-) glutamic oxaloacetic transaminase (GOT) was examined in the rat trigeminal, jugular and dorsal root ganglia by means of an indirect immunofluorescence method using antibodies specific for s- and m-GOT. Staining of s-GOT-like immunoreactivity was seen in giant, large, medium and small cells in these ganglia. On the other hand, m-GOT-like immunoreactivity was not seen in them. The distribution of GOT suggests that glutamate may be a transmitter released from primary sensory neurons.

Animals↗
PubMed1987

Alpha-fetoprotein and human chorionic gonadotropin-producing lung cancer.

A 73-year-old man had primary lung cancer that produced both alphafetoprotein (AFP) and human chorionic gonadotropin (HCG). The preoperative serum AFP level of 1039 ng/ml decreased to the normal range 8 weeks after surgery. The preoperative serum HCG level of 11 mIU/ml, which temporarily decreased to the normal range after operation, soon increased thereafter. The serum HCG level decreased, however, to the normal range after postoperative mediastinal radiation therapy. During relapse, only the serum HCG level increased gradually to 26,000 mIU/ml 7 weeks before his death. The lung cancer was classified histologically as poorly differentiated adenocarcinoma. Immunohistochemically, AFP was detected in the mononuclear tumor cells of the primary tumor in the lung, and HCG was found in the giant cells of the subcarinal metastatic lymph node. The concanavalin A non-reactive fraction rate for AFP was 81.3%, and appeared to differ from those of hepatocellular carcinoma and yolk sac tumor.

Adenocarcinoma↗
PubMed1987

Effect of exposure to carbon disulfide on tryptophan metabolism and the tissue vitamin B6 contents of rats.

Female Wistar rats were exposed to 100 ppm or 600 ppm carbon disulfide for 6 hours a day, 5 days a week for 12 weeks. During the exposure period, their urinary excretion of 4-pyridoxic acid was determined. The urinary excretions of xanthurenic acid and kynurenic acid after tryptophan loading were also determined. At the end of the exposure period, the rats were sacrificed and the levels of the five major forms of vitamin B6, pyridoxine, pyridoxal, pyridoxamine, pyridoxal phosphate and pyridoxamine phosphate, in the liver, kidneys and brain were determined by HPLC fluorometry. During the exposure the urinary excretions of xanthurenic acid and kynurenic acid after i.p. administration of tryptophan increased significantly in both experimental groups. However, urinary excretion of 4-pyridoxic acid decreased only slightly in the group exposed to carbon disulfide at 600 ppm and did not decrease in the group exposed to 100 ppm carbon disulfide. Furthermore, no significant changes were observed in the contents of vitamins B6 in any tissues examined. These results indicate that carbon disulfide does not cause vitamin B6 deficiency and thus that the disorders of tryptophan metabolism induced by carbon disulfide intoxication are not due to vitamin B6 deficiency.

Animals↗
PubMed1987

Subglottic neurofibroma in a child.

Reported here for the first time is a case of subglottic neurofibroma in an infant which was removed by laryngofissure. Neurofibromas are ubiquitous in distribution, but very rare in the larynx and also extremely rare in infancy. Only 9 cases had been reported in children under 9 years of age. In the present case, H.T., a boy aged 2 years and 7 months, complaining of inspiratory stridor since the beginning of December 1985, was admitted to our hospital on Jan. 21, 1986. The tumor was completely removed by laryngofissure and pathological diagnosis showed it to be a neurofibroma. Laryngeal neurofriboma cases are reviewed and discussed.

Child, Preschool↗