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H Harada

Publications and source records attributed to H Harada.

At least 595 records · Page 33Linked to original sources
PubMed1986

The maitotoxin-evoked Ca2+ entry into synaptosomes is enhanced by cholera toxin.

Effects of the Gs protein-mediated adenylate cyclase facilitatory system on Ca2+ entry into synaptosomes were studied, using two specific toxins. A putative Ca2+-channel agonist, maitotoxin (MTX), increased the 45Ca2+ entry and [Ca2+]i, determined with Quin-II, into synaptosomes of the rat brainstem, which were not attenuated by nifedipine. However, another Ca2+-channel agonist, BAY K-8644 did not alter the 45Ca2+ entry nor [Ca2+]i. The MTX-induced increase of the 45Ca2+ entry was significantly enhanced by addition of dibutyryl cyclic adenosine monophosphate and by the pretreatment with cholera toxin. These findings support the view that stimulation of presynaptic receptors coupled to the Gs-adenylate cyclase system may lead to a facilitation of the release of neurotransmitters, through a cAMP dependent enhancement of the opening of the Ca2+ channels located on nerve terminals.

Adenylyl Cyclases↗
PubMed1986

Prostaglandin production in cultured gastric mucosal cells: role of cAMP on its modulation.

The effect of cAMP on prostaglandin production may depend on cell types. To clarify the relationship between PG and cAMP, we examined arachidonate's effects on PG synthesis and intracellular cAMP accumulation in monolayers of rat gastric mucosal cells. These cells produced PGE2, PGI2 and thromboxaneA2 (TXA2) in amounts of 316 +/- 18, 100 +/- 7 and 30 +/- 5 pg per 10(5) cells in 10 min, respectively, in response to 10 microM arachidonic acid (AA). The production of these PG, however, leveled off subsequently. Cells initially exposed to AA responded poorly to a subsequent stimulation by AA. AA simultaneously stimulated intracellular cAMP accumulation; this stimulatory effect on cAMP production was abolished by the pretreatment with indomethacin. Nevertheless, the pretreatments with dibutyryl cAMP (0.1-5 mM) did not alter the amount of subsequent AA-induced PGE2 production. Furthermore, the preincubation with 1mM isobutyl methyl xanthine also failed to affect PGE2 synthesis, while it increased intracellular cAMP accumulation. Our studies suggest AA stimulates intracellular cAMP formation in cultured gastric mucosal cells, linked with conversion of AA to cyclooxygenase metabolites, AA-induced PG production is limited in these cells, and it seems, however, unlikely that intracellular cAMP modulates AA metabolism to PG.

Animals↗
PubMed1986

Auxin-controlled glycoprotein release into the medium of embryogenic carrot cells.

Glycoproteins released from carrot cells into culture media were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and visualized by staining with Coomassie brilliant blue or with the periodic-acid Schiff procedure. The appearance or disappearance of two glycoproteins of M(r) 65,000 (GP65) and M(r) 57,000 (GP57) was closely related to the formation of somatic embroys. GP65 was released specifically from embryogenic cells cultured in a medium without 2,4-dichlorophenoxyacetic acid, in which they can form somatic embryos. GP57 was released from the same embryogenic cells, if they were cultured in a medium with 2,4-dichlorophenoxyacetic acid, in which they cannot form somatic embryos. Nonembryogenic cells which cannot form somatic embryos, released only GP57.

Journal Article↗
PubMed1986

Pathological study on mucosal changes in small intestine of rat by oral administration of ricin. I. Microscopical observation.

A histological study on small intestine of Wistar rats after oral administration of ricin, a proteinous toxin from castor bean seeds, was carried out. In Experiment I, the jejunum was examined at 1, 2, 5, 10, 15, 20, 24, and 40 hours after oral administration of ricin 30 mg/kg. In Experiment II, ricin was administered at dose of 1, 3, 5, 10, 15, 30, and 60 mg/kg, and after 5 hours the jejunum, mid-portion, and ileum were examined. For comparison, ricin 0.5 mg/kg was administered intraperitoneally and castor bean hemagglutinin (CBH) 30 mg/kg orally. In both experiments, the changes of mucosa were essentially similar dependent on time-lapse and dose respectively, which were atrophy of villus, elongation of crypt, degeneration of epithelium, decrease of goblet cell, fusion of intervillous epithelia, infiltration of neutrophils and eosinophils, and dissociation between epithelium and lamina propria. These changes were most manifest in the jejunum that was contacted with ricin first in a high concentration. In contrast, intraperitoneal administration of ricin caused only dissociation between epithelium and lamina propria and oral administration of CBH caused only milder atrophic changes. The evidences suggest that the mucosal changes by oral administration were caused by direct contact with ricin.

Administration, Oral↗
PubMed1986

Stimulation of cardiac slow Ca++ current by high concentration of cimetidine.

Electrophysiological studies on the cardiac effects of a H2-antagonist, cimetidine, were examined in three kinds of preparations: guinea-pig papillary muscles, rat left atria and perfused chick hearts. Cimetidine (10(-5) to 10(-4) M) depressed or abolished the slow action potentials (APs) induced by histamine (10(-5) to 10(-4) M) in hearts whose fast Na+ channels had been inactivated by 25 mM K+. Higher concentrations of cimetidine (10(-3) to 5 X 10(-3) M) increased myocardial cyclic AMP level and allowed the generation of slow APs in such inexcitable tissues. These cimetidine-induced slow APs were not prevented by propranolol (10(-6) to 10(-5) M) or pretreatment with 6-hydroxydopamine (50 mg/kg). These results suggest that cimetidine, in doses higher than that required to block cardiac H2-receptors, may have a cardio-stimulating action mediated through increase of inward Ca++ current.

Action Potentials↗
PubMed1986

[Clinical experience of methylcobalamin (CH3-B12)/clomiphene citrate combined treatment in male infertility].

Infertile men (excluding azoospermia) were divided into three groups to test methylcobalamin (CH3-B12) + clomiphene citrate (Clomid) treatment. Group M: CH3-B12 (1,500 micrograms/day, daily for 8 to 60 weeks), Group C: Clomid (25 mg/day for 25 days followed by a 5-day rest period, for 8 to 48 weeks), and Group MC: CH3-B12 + Clomid (CH3-B12: 1,500 micrograms/day, daily and Clomid: 25 mg/day for 25 days followed by a 5-day rest period, for 12 to 24 weeks semen analysis was conducted before and after these administrations. Judging by our criteria, 60.0% (24/40) of the cases in Group M, 71.4%(25/35) in Group C, and 66.7% (8/12) in Group MC were improved. However, in patients whose sperm concentrations were over 10 X 10(6)/ml, 61.9% (13/21) of the cases in Group M, 69.2% (9/13) in Group C, and 80.0% (4/5) in Group MC were improved. Therefore, CH3-B12 + Clomid treatment was successful for patients whose sperm concentrations was over 10 X 10(6)/ml.

Adult↗
PubMed1985

Therapeutic effect of taurine in congestive heart failure: a double-blind crossover trial.

In a double-blind, randomized, crossover, placebo-controlled study, we investigated the effects of adding taurine to the conventional treatment in 14 patients with congestive heart failure for a 4-week period. Compared with placebo, taurine significantly improved the New York Heart Association functional class (p less than 0.02), pulmonary crackles (p less than 0.02), and chest film abnormalities (p less than 0.01). A benefit of taurine over placebo was demonstrated when an overall treatment response for each patient was evaluated on the basis of clinical examination (p less than 0.05). No patient worsened during taurine administration, but four patients did during placebo. Pre-ejection period (corrected for heart rate) decreased from 148 +/- 14 ms before taurine treatment to 137 +/- 12 ms after taurine (p less than 0.001), and the quotient pre-ejection period/left ventricular ejection time decreased from 47 +/- 9 to 42 +/- 8% (p less than 0.001). Side effects did not occur in the patients during taurine. The results indicate that addition of taurine to conventional therapy is safe and effective for the treatment of patients with congestive heart failure.

Administration, Oral↗
PubMed1985

Studies on the effect of glucagon on human pancreatic secretion by analysis of endoscopically obtained pure pancreatic juice.

The effect of glucagon on human exocrine pancreatic secretion was evaluated in ten patients by analysis of pure pancreatic juice. Pancreatic juice was obtained by endoscopic cannulation of the pancreatic duct at 2-min intervals during constant intravenous infusion of secretin (1 U per kg of body weight per hr) plus caerulein (0.04 micrograms per kg of body weight per hr). Since steady secretion was established 20 minutes after the start of juice collection, a further five 2-min fractions were collected as controls, then constant intravenous infusion of glucagon (15 micrograms per kg of body weight per hr) was commenced. Pancreatic juice was collected for a further 20 minutes. The control fractions and post-glucagon fractions were compared in each patient using Student's test. Glucagon depressed secretin-caerulein-stimulated pancreatic secretions. More uniform reductions were observed in the concentration and output of protein and enzymes. Individual variations were observed in the secretory volume and bicarbonate concentration and output. Amylase and lipase were depressed in a parallel fashion in seven patients and in the remaining three, amylase was more depressed than lipase. The post-glucagon reduction in pancreatic secretion was not proportional to the rise in plasma glucagon and blood glucose.

Adenocarcinoma↗
PubMed1985

Studies on Conditions for Cell Division and Embryogenesis in Isolated Pollen Culture of Nicotiana rustica.

A method for the induction of a high rate of cell division and embryogenesis of Nicotiana rustica pollen was developed. Binucleate pollen grains were fractionated by Percoll density gradient (35/45%) centrifugation and cultured in 0.4 molar mannitol at 30 degrees C (the first culture). After 3 days in culture pollen was recollected by a second Percoll fractionation (0/30%) and transferred to and cultured in a medium containing the Murashige-Skoog macro-elements, 0.4 molar mannitol, 40 millimolar galactose, 3 millimolar glutamine, and 5 micromolar ABA for 10 days (the second culture). The cell population consisting of about 80% dividing pollen was transferred to a Murashige-Skoog medium containing 0.4 molar mannitol, 3 millimolar glutamine, and no phytohormone (the third culture), where about 40% of dividing pollen developed into embryos or embryogenic calli.

Journal Article↗