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Biomedical subjects

H Wada

Publications and source records attributed to H Wada.

At least 919 records · Page 51Linked to original sources
PubMed1987

Affinity purification and characterization of serine hydroxymethyltransferases from rat liver.

A rapid and simple method was developed for the purification of serine hydroxymethyltransferases [EC 2.1.2.1]. The procedure involved ammonium sulfate precipitation, DEAE-cellulose column chromatography and affinity chromatography on an L-adsorbent. Through this procedure the cytosolic enzyme (s-SHMT) was purified 1,650-fold, and the mitochondrial enzyme (m-SHMT) 1,730-fold, with a yield of more than 30% in both cases. Both preparations gave a single band with a Mr of 54,000 on SDS-PAGE. The native enzymes both contained 4 mol of pyridoxal phosphate/mol of enzyme, and showed a Mr value of 220,000 on gel filtration, indicating a tetrameric structure. Several other properties of the enzymes were also studied.

Animals↗
PubMed1987

Purification of L-dopa decarboxylase from rat liver and production of polyclonal and monoclonal antibodies against it.

L-DOPA decarboxylase [DDC, aromatic-L-amino acid carboxyl-lyase, EC 4.1.1.28] was purified 800-fold from rat liver by several column chromatographic steps. The enzyme (specific activity, about 6 mumol/min X mg protein) had a molecular weight of 100,000 and gave a single band with a molecular weight of 50,000 on SDS-polyacrylamide gel electrophoresis. Its isoelectric point was pH 5.7. The absorption spectrum in the visible region of the purified DDC showed maxima at 330 and 420 nm. Polyclonal and monoclonal antibodies against DDC were produced by using this purified protein as an antigen. Polyclonal anti-DDC serum immunoprecipitated the DDC activities of rat, guinea-pig and rabbit livers (about 1, 10, and more than 100 microliter of antiserum, respectively, were required for 50% precipitation of 2 nmol/min of activity of these enzymes). The monoclonal antibody, named MA-1, belonged to the IgG1 subclass and immunoprecipitated the DDC activities of rat and guinea-pig livers to the same extent (about 0.5 micrograms of IgG was required to immunoprecipitate 2 nmol/min activity of each enzyme), but it did not affect the rabbit enzyme. The antibody MA-1 detected DDC molecules of both the purified enzyme and crude homogenate of rat liver blotted onto a nitrocellulose sheet. Immunohistochemically this antibody also stained specific neurons in the substantia nigra, raphe nucleus and locus coeruleus of rat brain.

Animals↗
PubMed1987

Induction of histidine decarboxylase in non-mast cells in the spleen of mice by injection of staphylococcal enterotoxin A.

Injection of Staphylococcal enterotoxin A (SEA) into WBB6F1-W/WV mice genetically deficient in mast cells resulted in a 10-fold increase in the histidine decarboxylase [HDC, L-histidine carboxylase, EC 4.1.1.22] activity of their spleen. The nature of the spleen cells responsible for this increased HDC activity was studied. The HDC induction by SEA was abolished on day 1 after X-ray irradiation of the mice at 400 rad and restored by transplantation of bone marrow cells from normal WBB6F1-+/+ littermates into the X-ray irradiated WBB6F1-W/WV mice. Transplantation of cells from other organs of the normal mice, such as the thymus, mesenteric lymph node and spleen, did not restore the HDC increase significantly. Transplantation of cultured mast cells also did not restore the increase. Moreover, the high HDC activity of spleen cells induced by SEA was not affected by their treatment with anti-Thy-1,2 antibody and complement. Depletion of phagocytes from the spleen by treatment with carbonyl iron resulted in decrease in HDC activity. These results suggested that phagocytic cells derived from haemopoietic stem cells of the bone marrow were responsible for the increase in HDC activity induced by SEA.

Animals↗
PubMed1987

Solubilization and characterization of the nitrendipine receptor in rat brain.

The nitrendipine receptor associated with the voltage-dependent calcium channel in rat brain was solubilized by detergent extraction and sonication. The detergent solution used for extraction consisted of 10 mM 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS), 0.25% (wt/vol) polyoxyethylene 20 cetyl ether (Brij 58), and 0.025% (wt/vol) polyoxyethylene 17 cetyl stearyl ether (Lubrol WX) in the presence of 30% (wt/vol) glycerol as a stabilizer. The molecular weight of the receptor was estimated to be 1,800K by Sephacryl S-500 gel filtration and 800K by sucrose density gradient sedimentation. The equilibrium dissociation constant of [3H]nitrendipine to the solubilized receptors was 5.6 nM, which is approximately 10 times that of the membrane-bound receptor. The binding of nitrendipine to the receptor was inhibited noncompetitively by the structurally unrelated calcium channel inhibitors verapamil and prenylamine; their concentrations for 50% inhibition were both 1.0 X 10(-7) M, and they caused maximal inhibitions of 70 and 100%, respectively.

Animals↗
PubMed1987

Involvement of H1 histamine receptor in basal and estrogen-stimulated luteinizing hormone-releasing hormone secretion in rats in vitro.

For determination of the roles of histamine and its receptors, H1 and H2, in the control of basal and estrogen-induced LH-RH secretion, the mediobasal hypothalamus (MBH) and/or pituitary was excised from normally cycling female rats and perifused in an in vitro sequential double chamber perifusion system. Administration of 10(-7) M histamine caused significant release (90-170% increase, p less than 0.05) of LH from the pituitary in sequence with the MBH, whereas 10(-7) M histamine had no effect on LH release from the pituitary perifused alone; administration of 10(-5) M 2-methylhistamine, an H1 agonist, induced significant release (50-120% increase, p less than 0.05) of LH-RH from the MBH, and addition of 10(-5) M mepyramine, and H1 antagonist, abolished this LH-RH release. The LH concentrations in the efflux were not affected by the administration of the H2 agonist 4-methylhistamine. Estradiol caused significant release of LH-RH from the MBH and LH from the pituitary in sequence with the MBH. The estradiol-induced release of LH-RH and LH were completely abolished by perifusion with medium containing 10(-5) M mepyramine. The H2 receptor antagonist ranitidine did not affect estradiol-induced LH release. Histamine did not change the LH release induced by 20 ng LH-RH. These findings suggest that histamine induces release of hypothalamic LH-RH, and that histamine H1 receptors in the hypothalamus are involved in the basal and estradiol-induced LH-RH release.

Animals↗
PubMed1987

Histaminergic neuromodulation of the release of vasopressin.

In an attempt to clarify the nature of histaminergic neuromodulation of the vasopressinergic system, several studies under different experimental paradigms were carried out. L-Histidine loads (8 mmol/kg, i.p.) induced a marked increase in histamine (HA) in the anterior (AHR) and posterior (PHR) hypothalamic regions, the median eminence (ME) and adenohypophysis (Ah) with no apparent effect on the concentration of HA in the neurohypophysis (Nh), as measured by high-performance liquid chromatography. These findings correlated with decreases in vasopressin (VP) levels in the AHR and ME, accompanied by increases of the neuropeptide in the PHR and Ah. Intraperitoneal injections of HA (6 mumol/kg), resulted in a significant (p less than 0.005) rise in VP levels in the PHR, ME and Ah. HA induced an elevation of VP in the prefrontal cortex (PFC) from 6.23 +/- 2.02 to 43 +/- 4.05 microU/mg, as well as a 60% reduction in neurohypophyseal VP. These HA-induced VP responses were abolished by both mepyramine (3 mumol/kg) and famotidine (4 mumol/kg) in the PHR and PFC. Mepyramine suppressed the HA-induced VP response in the Ah and enhanced it in the Nh, while famotidine did the opposite. When alpha-fluoromethylhistidine (FMH), an irreversible inhibitor of histidine decarboxylase, was administered at doses of 100 mg/kg/day (i.p.), hypothalamic HA levels fell by 40-45% after 1 h, by 50% after 3 h, and by 65-80% after 24 h in adrenalectomized rats. In the same conditions, but after a week of treatment with FMH, the VP response to adrenalectomy was clearly impaired.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Time- and dose-dependent responses of brain histamine to intracerebroventricular and intraperitoneal administrations of growth hormone-releasing factor (GRF1-44).

Changes in the level of histamine (HA) in rat brain induced by intracerebroventricular (i.c.v.) and intraperitoneal (i.p.) administrations of growth hormone-releasing factor (GRF1-44) were studied. HA was determined by high-performance liquid chromatography (HPLC) in the anterior hypothalamic region, posterior hypothalamic region, median eminence, adenohypophysis, neurohypophysis, hippocampus and prefrontal cortex. GRF1-44 (1-10 micrograms, i.c.v.) induced significant time- and dose-dependent increases in the concentration of HA in the hypothalamo-hypophyseal system and time-dependent decrease of HA in the hippocampus. In contrast, after i.p. administration of GRF1-44 (10 micrograms) the level of HA in the hypothalamus tended to decrease but the total amount of H-1 receptors in the hypothalamo-hypophyseal system did not change. Circadian variations in the GRF-induced HA and growth hormone responses were also observed, responses being lower in the evening than in the morning. It is concluded that GRF interacts with HA at the central level to optimize the function of the somatotropinergic system.

Animals↗
PubMed1987

Somatostatin-induced histamine response in the rat central nervous system.

The effects of somatostatin (SS-14) (0.1-10 micrograms, i.c.v.) on brain histamine (HA) in male Wistar rats were investigated. HA was measured by HPLC with a cation exchanger and an automated fluorometric detection system. SS-14 induced time- and dose-dependent changes in the levels of HA in the anterior hypothalamus, posterior hypothalamus, median eminence, adenohypophysis, hippocampus, and frontal cortex. In the anterior hypothalamus, posterior hypothalamus and hippocampus, SS-14 (1 microgram, i.c.v.) significantly (p less than 0.01) decreased the levels of HA from 5 to 30 min. This response was delayed by 5 min in the frontal cortex and adenohypophysis. Only in the neurohypophysis, SS-14 increased the concentration of HA 10 min after injection, but this response was not dose-related. These results seem to indicate that SS-14 influences neuronal HA probably modifying HA release, it leading to a decrease of the levels of the biogenic amine in specific areas of the brain. Since this effect is opposite to that developed by growth hormone-releasing factor (GRF) in identical conditions, HA seems to fulfil the criteria by which a neuroendocrine modulator should currently respond in a specific time- and dose-dependent manner to those neuropeptides which modulate. Therefore, HA is likely to play a key role as a neuromodulator of the somatotropinergic system in the rat.

Animals↗
PubMed1987

[Malignant germ cell tumors in the mediastinum].

Mediastinal germ cell tumors are divided into seminomas and non-seminomatous germ cell tumors. The former is a radiosensitive tumor that can be successfully treated by surgery and radiation. The latter is much more malignant than the former, however, the therapy has been making remarkable progress owing to CDDP. Nevertheless, the median survival time of patients with mediastinal involvement is 14 months, much lower than that seen in patients with testicular involvement. From our 12 patients and a review of the literature, we drew the following conclusions. If malignant germ cell tumors are suspected among anterior mediastinal tumors affecting male patients of around 20 years old, tumor markers such as AFP and HCG must be investigated and then, tissue histology should be diagnosed from specimens obtained by mediastinoscopy or anterior mediastinotomy. In the case of NSGCT, or AFP and/or hCG producing seminoma, the first choice is the chemotherapy including CDDP. Seminomas, that do not produce either AFP or HCG, can be treated by surgery and radiation. If the patients have tumor markers such as AFP and/or HCG, these are very useful to evaluate the efficacy of the therapy. When the efficacy of chemotherapy reaches the maximum, adjuvant surgery may be indicated. Chemotherapy should be continued, when malignant tissues are present in the resected mass.

Adolescent↗