Biomedical subjects

Y Masuda

Publications and source records attributed to Y Masuda.

At least 577 records · Page 32Linked to original sources

PubMed1991

Potassium channel opening properties of a novel compound, NIP-121, cromakalim and nicorandil in rat aorta and portal vein.

A novel compound, NIP-121, cromakalim and nicorandil caused concentration-dependent relaxation of rat aortas precontracted with 30 mM KCl, with pEC50 (M) values of 8.2, 7.1 and 5.5, respectively. At 60 mM KCl, the vasorelaxation induced by NIP-121 or cromakalim was almost abolished whereas that induced by nicorandil remained. In preparations precontracted with prostaglandin F2 alpha(PGF2 alpha) (10(-5) M), glibenclamide (10(-7) M) and phentolamine (3 x 10(-6), 3 x 10(-5) M) antagonized the relaxation induced by NIP-121 and cromakalim but not that induced by nicorandil. Methylene blue (10(-5) M) showed antagonistic effects against the vasorelaxation induced by nicorandil but not that induced by NIP-121. NIP-121 (10(-7), 10(-6) M) and cromakalim (10(-6), 10(-5) M) significantly increased the 86Rb+ efflux rate in rat aorta. The three compounds inhibited the frequency of spontaneous contractions of the rat portal vein (pIC30; NIP-121 = 8.0, cromakalim = 7.1 and nicorandil = 4.9); glibenclamide and phentolamine antagonized the effects of these compounds. In conclusion, NIP-121 is a more potent K+ channel opener than cromakalim in these tissues. Nicorandil apparently behaves as a K+ channel opener in the rat portal vein, but the vasorelaxation may involve some other mechanisms, such as generation of cyclic GMP.

Animals↗

PubMed1991

Lymph nodes in incipient adult T-cell leukemia-lymphoma with Hodgkin's disease-like histologic features.

Lymph nodes were examined from four patients with incipient adult T-cell leukemia-lymphoma (ATLL) who had mild lymphadenopathy, fatigue, no or a few atypical lymphocytes in their peripheral blood, and integrated proviral human T-cell lymphotrophic virus type I (HTLV-I) DNA in the nodes. The HTLV-I DNA was detected by southern blot analysis and/or polymerase chain reaction in the lymph nodes of all cases. The nodal architecture was preserved. Some scattered or aggregated highly lobular, cerebriform, or Reed-Sternberg-like giant cells were observed, with occasional mitoses and diffuse infiltration of small to medium-sized lymphocytes, with no or minimal nuclear abnormalities in the enlarged paracortex. The giant cells were usually positive for Ki-1 and also for UCHL-1 and other T-cell markers but negative for Ber-H2. Rearrangement and/or deletion of T-cell receptors were found in three of four patients. All patients died within 2 years, with transformation to overt leukemia-lymphoma occurring in three patients, and pulmonary carcinoma in one. The incipient or prelymphomatous phase of ATLL should be differentiated from Hodgkin's disease because of the distinctly different prognoses of these two diseases.

Aged↗

PubMed1991

Effects of submergence on development and gravitropism in the coleoptile of Oryza sativa L.

Caryopses of rice (Oryza sativa L. cv. Sasanishiki) were germinated in air or under water. In submerged seedlings a twofold increase in coleoptile growth rate and an inhibition of root growth was observed. The amount of starch in the amyloplasts of submerged coleoptiles was substantially reduced compared to the air-grown control plants and plastids had a proplastidic character. During the rapid elongation of coleoptiles under water, the osmotic concentration of the press sap remained constant, whereas in air-grown coleoptiles a decrease was measured. Determination of curvature of gravistimulated air-grown and submerged shoots was carried out by placing the coleoptiles horizontally in air of 98% relative humidity. Air-grown coleoptiles reached a vertical orientation within 5 h after onset of gravistimulation. In coleoptiles germinated under water the first signs of consistent negative gravitropic bending occurred after 4-5 h and curvature was complete after 24 h. During the first 5 h of gravistimulation the water-grown coleoptiles grew at an average rate of 0.39 mm h-1, whereas in air-grown coleoptiles a rate of 0.27 mm h-1 was measured. Concomitant with the delayed onset of gravitropic bending of the water-grown coleoptiles, a change in plastid ultrastructure and an increase in starch content was observed. We conclude that the gravitropic responsiveness of the rice coleoptile depends on the presence of starch-filled amyloplasts.

Cotyledon↗

PubMed1991

A prospective study of tardive dyskinesia in Japan.

A large-scale, prospective study of tardive dyskinesia (TD) was performed in 11 psychiatric facilities in Japan. A total of 1595 psychiatric patients were enrolled in this study in 1987. The progress of these patients, with the exception of 490 dropouts, has now been followed up to 1988. The prevalence of TD at study entry was 7.6%, the annual incidence rate was 3.7% and the annual remission rate was 28.7%. Newly developed TD patients tended to be older, to have undergone more psychosurgery, and to have had lower neuroleptic doses than the patients who had not developed TD, whereas no specific variable could be detected as a factor associated with remission of TD. The results suggest that the incidence of TD is lower in Japan than that in Europe and North America.

Antipsychotic Agents↗

PubMed1991

Proliferating cells in histiocytic necrotizing lymphadenitis.

The phenotypes of proliferating cells in histiocytic necrotizing lymphadenitis (HNL) were examined. The affected areas consisted mainly of CD 8-positive (suppressor/cytotoxic T-cells) and CD 4-positive (helper/inducer T-cells) in association with some CD 15-positive cells (monocytes). A marker of proliferating cells (Ki-67) and monoclonal antibodies for determining the phenotypes of cells (CD 4, CD 8, CD 15) in the affected areas were applied using a double-staining method. Ki-67-positive proliferating cells were mainly CD 8-positive. A few CD 4-positive cells and rare CD 15-positive cells were also Ki-67-positive. The percentage of CD 8-positive cells increased gradually over time and the ratio of CD 8-positive to proliferating cells did not decrease throughout the observation period of 6 weeks. These results suggest that the proliferation of CD 8-positive T-cells together with the accumulation of CD 4- and CD 15-positive cells is the main phenomenon occurring in HNL.

Adolescent↗

PubMed1991

Alpha-interferon in Kikuchi's disease.

In Japan, histiocytic necrotizing lymphadenitis (Kikuchi's disease) is a relatively common reactive lesion affecting lymph nodes, but the histogenesis and pathogenesis of the disease have not been clarified. Alpha-interferon has a role in the body's defense against viral infections. Using a polyclonal antibody to human alpha-interferon, we found numerous cells, mainly histiocytes, containing alpha-interferon in affected foci in the lymph nodes from 24 patients with Kikuchi's disease. Tubuloreticular structures, thought by some authors to be associated with the production of interferon, were detected by electron microscopy in histiocytes, activated lymphocytes and vascular endothelial cells in the affected foci. These results suggested that the formation of tubuloreticular structures is a secondary phenomenon following stimulation by alpha-interferon. Further, the activity of 2'-5' oligoadenylate synthetase, which is induced by alpha-interferon and enhanced during the early or active stage of viral infection, showed increased levels of activity in the active stage of Kikuchi's disease and decreased to normal levels in the convalescent stage 2 weeks later. These results suggested the possibility of a viral etiology for Kikuchi's disease.

2',5'-Oligoadenylate Synthetase↗

PubMed1991

The enhancement of the hypomotility induced by small doses of haloperidol in the phase of dopaminergic supersensitivity in mice.

Dopaminergic supersensitivity in mice was induced by pretreatment with a single injection of haloperidol (4.8 mg/kg). After the pretreatment, further treatment with haloperidol (0.6 or 0.01 mg/kg) was made at varying intervals, and catalepsy, locomotor activity and homovanillic acid (HVA) were measured. The intensity of the supersensitivity was evaluated by enhanced apomorphine (1 mg/kg)-induced climbing behavior. Supersensitivity was displayed on the 2nd and the 4th day. The cataleptogenic effect of haloperidol (0.6 mg/kg) was significantly weakened on the 1st, 2nd and 4th days. The motor inhibitory effect of haloperidol (0.01 mg/kg) increased on the 1st, 2nd and 4th days. Homovanillic acid was measured in the striatum and the prefrontal cortex on the 2nd day. Haloperidol (0.6 mg/kg) increased the concentrations of HVA in both regions of the brain. The increase in the concentrations of HVA in the striatum was blunted after the pretreatment, but such tolerance did not develop in the prefrontal cortex. Haloperidol (0.01 mg/kg) did not influence the concentration of HVA in both regions. These results suggest that the behavioral effect of a small dose of haloperidol may be enhanced, rather than reduced, in the phase of supersensitivity.

Animals↗

PubMed1991

Characterization of endothelin receptor subtypes.

Scatchard-plot analysis of [125I]ET-1 and [125I]ET-3 binding to rat lung membranes exhibited almost the same Kd values whereas the concentration of the binding sites of ET-1 is approximately four times higher than that of ET-3. This result suggests the presence of at least two distinct subtypes of ET receptors: an ET-1-specific type and an ET-3-specific or ET-1 and ET-3 nonselective type. On the other hand, in rat brain membranes, a curvilinear Scatchard plot was obtained for [125I]ET-3 in contrast to a linear plot for [125I]ET-1. This finding also demonstrates the existence of the two different receptor subtypes having the same affinity for ET-1, but one of which has a high affinity and the other has a low affinity for ET-3. Moreover, these data indicate that an ET receptor subtype exists in rat brain different from the subtype in rat lung. To obtain the bases for a further detailed characterization of the receptor, we have purified the rat lung ET receptor to homogeneity by ET-1-affinity chromatography. The purified receptor exhibits a molecular mass of 45 kDa, in good agreement with that estimated from the affinity labeling.

Animals↗

PubMed1991

The antihypertensive property of NIP-121, a novel potassium channel opener in rats.

The antihypertensive effects of NIP-121, a novel potassium channel opener, were examined in comparison with cromakalim and its active enantiomer, lemakalim. In experiments by direct blood pressure measurements, orally administered NIP-121 dose-relatedly decreased arterial blood pressure in conscious spontaneously hypertensive rats (SHRs), and the ED20 values (the doses to produce 20% decrease of the mean blood pressure) of NIP-121 and cromakalim were 0.010 and 0.11 mg/kg, respectively, NIP-121 thus being about ten times more potent than cromakalim. The duration of the hypotensive effect by NIP-121 was longer than that by cromakalim. The hypotensive effect of NIP-121 was stronger in SHRs than in normotensive rats. All three drugs showed tachycardia that was antagonized by a beta-blocker, propranolol. Intravenously administered NIP-121 also showed a more potent hypotensive action with longer duration than cromakalim in conscious SHRs. The ED20 values for hypotension by NIP-121, cromakalim, and lemakalim were 0.017, 0.040, and 0.016 mg/kg, respectively. The intravenous hypotensive potency of NIP-121 but not cromakalim was similar to that of p.o. administration. The repeated treatments with NIP-121 (0.025, 0.05, and 0.1 mg/kg p.o. once a day) for 15 days did not modify the degree of the hypotensive action. In the anesthetized SHRs, pretreatment with glibenclamide but not other antagonists (atropine, propranolol, diphenhydramine + cimetidine, or indomethacin) suppressed the decrease in blood pressure induced by NIP-121.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗

PubMed1991

Xyloglucan antibodies inhibit auxin-induced elongation and cell wall loosening of azuki bean epicotyls but not of oat coleoptiles.

Polyclonal antibodies were raised in rabbits against isoprimeverose (Xyl(1)Glc(1)), xyloglucan heptasaccharides (Xyl(3)Glc(4)), and octasaccharides (Gal(1)Xyl(3)Glc(4)). Antibodies specific for hepta- and octasaccharides suppressed auxin-induced elongation of epicotyl segments of azuki bean (Vigna angularis Ohwi and Ohashi cv Takara). These antibodies also inhibited auxin-induced cell wall loosening (decrease in the minimum stress-relaxation time and the relaxation rate of the cell walls) of azuki segments. However, none of the antibodies influenced auxin-induced elongation or cell wall loosening of coleoptile segments of oat (Avena sativa L. cv Victory). Auxin caused a decrease in molecular mass of xyloglucans in the cell walls of azuki epicotyls and oat coleoptiles. The antibodies inhibited such a change in molecular mass of xyloglucans in both species. Preimmune serum exhibited little or no inhibitory effect on auxin-induced elongation, cell wall loosening, or breakdown of xyloglucans. The results support the view that the breakdown of xyloglucans is associated with the cell wall loosening responsible for auxin-induced elongation in dicotyledons. The view does not appear to be applicable to poaceae, because the inhibition of xyloglucan breakdown by the antibodies did not influence auxin-induced elongation or cell wall loosening of oat coleoptiles.

Journal Article↗

PubMed1991

Presence of human papillomavirus type 18 DNA in a pharyngeal and a laryngeal carcinoma.

We examined the presence of human papillomavirus (HPV) genome in pharyngeal and laryngeal squamous cell carcinomas by employing the polymerase chain reaction. We detected HPV 16 DNA in one of 11 pharyngeal carcinomas and in 3 of 28 laryngeal carcinomas, and HPV 18 DNA in a pharyngeal and a laryngeal carcinoma. In one of the laryngeal carcinomas, DNA of both HPV types 16 and 18 were detected. To our knowledge, this is the first report of detection of HPV type 18 in head and neck carcinomas.

Adult↗

PubMed1991

Effect of dextrans of various molecular weights on mesangial transport in ddY mice pretreated with sheep anti-type IV collagen serum.

The authors' previous report concluded that increased mesangial IgA deposition seen in ddY mice pretreated with mesangiotropic anti-type IV collagen serum might be due to a dysfunction of mesangial transport of macromolecules such as polymeric autologous IgA. In the present study we examined the effect of macromolecules upon mesangial transport in similarly treated ddY mice, using intravenously administered FITC-labeled dextrans of various molecular weights as tracers. The intensity of each resulting mesangial dextran deposit inspected directly by immunofluorescence was measured periodically and compared with the deposition of autologous mouse IgA examined using rhodamine-labeled rabbit anti-mouse IgA. High-molecular-weight dextran of 2,000 kDa showed prolonged mesangial deposition which paralleled the intensity and distribution of the autologous mouse IgA deposition. In contrast, medium- and low-molecular-weight dextrans of 500 and 150 kDa, respectively, disappeared earlier from the mesangium, unlike the autologous IgA deposition which persisted. Based on these results, it was concluded that the macromolecularity of certain substances and a transport dysfunction of the mesangium may both be major factors in prolonged mesangial deposition. These findings may provide some clues to help clarify the pathogenesis of human IgA nephritis.

Animals↗

PubMed1991

Epstein-Barr viral genomes in carcinoma metastatic to lymph nodes. Association with nasopharyngeal carcinoma.

Lymphoepithelioma of the nasopharynx is a neoplasm known to have a strong association with Epstein-Barr virus (EBV). Using the Southern blot method, polymerase chain reaction (PCR), and/or in situ hybridization, we examined lymph nodes containing metastatic carcinoma, including metastatic lymphoepithelioma, for the presence of EBV genomes in order to determine whether EBV was associated exclusively with lymphoepithelioma. All of six lymph nodes from patients with lymphoepithelioma in the neck were found to have EBV genomes using the above methods. In four of the six cases, the primary site was the nasopharynx, and in the other two no primary site was found. Four of 12 squamous cell carcinomas and one of 18 adenocarcinomas expressed the EBV genome only by PCR, but not by Southern blotting or in situ hybridization, probably due to the presence of latent EBV in lymphocytes. These results indicate that metastatic carcinoma in lymph nodes showing EBV genomes revealed by Southern blotting or in situ hybridization is lymphoepithelioma, and that the nasopharynx is very likely the primary site.

Adenocarcinoma↗

PubMed1991

[Bacterial meningitis in the elderly with neurosurgical procedures].

Bacterial meningitis is one of complications in the elderly with neurosurgical procedures. In an attempt to find the clinical features of this complication we analyzed 10 cases, which were found in 30 cases of the bacterial meningitis in Tokyo Metropolitan Geriatric Hospital from 1972 to 1989. The patients were 4 males and 6 females, 52-86 years old (the mean, 69). While 2 Enterococcus species were isolated after craniotomy, Staphylococci were common pathogens (4 S. aureus, 4 S. epidermidis and 1 P. aeruginosa) in patients with shunt infection. Most of these patients lacked typical manifestations of meningitis except the fever. Symptoms occurred long after surgery with little abnormality in the data of serum and cerebrospinal fluid. However, blood cultures were positive in 75% of the cases. Removal of the infected catheter was effective in the cases of shunt infection.

Aged↗

PubMed1991

Effects of beta-adrenergic agonists on metabolic activations of human neutrophils.

Although effects of adrenergic agonists on metabolic activation of neutrophils have been studied for over a decade, amounts of released arachidonic acid and its metabolites from the cells activated by chemotactic peptide (FMLP) are so small that the results have been in conflict. In this study, we developed a method to obtain enough amount of arachidonic acid released to examine the action sites of adrenergic agonists with respects to the metabolic bursts of human neutrophils. First, superoxide generation from the cells was estimated and the results indicated that the adrenergic agonists, such as isoproterenol, salbutamol, procaterol and epinephrine, inhibited over 70% and 40% of the superoxide generation stimulated by FMLP and serum treated zymosan (STZ), respectively. Another metabolic activation, the release of arachidonic acid, was achieved by FMLP if the cells were incubated with merthiolate (20-80 microM), but the merthiolate-treatment was ineffective on the cells activated by calcium ionophore (A23187). Isoproterenol and epinephrine decreased the arachidonic acid release only when the cells were activated by FMLP in the presence of merthiolate. In spite of the fact that isoproterenol (1 and 10 microM) hardly inhibited the arachidonic acid release activated by A23187, formations of leukotrienes were decreased up to approximately 70% of control level. Intracellular calcium concentration elevated by FMLP was hardly diminished by isoproterenol and salbutamol. From these observations, it appears likely that adrenergic agonists attenuate the signal transmission process of FMLP at a post-receptor site of action at a step before the activation of protein kinase C or phospholipase A2.

Adrenergic beta-Agonists↗

PubMed1991

Inhibitory effects of histamine H1 receptor blocking drugs on metabolic activations of neutrophils.

Inhibitory effects of various histamine receptor-blocking agents including antiallergic agents on metabolic activations of neutrophils were examined by measuring leukotrienes (C4, D4 and E4) formation, arachidonic acid release and superoxide generation. The stimulation of neutrophils by calcium ionophore (A23187) causes the production of leukotrienes concomitantly with the release of arachidonic acid from the cells and these were effectively diminished with a variety of antihistaminic agents. Almost all the histamine H1 receptor-blocking drugs studied here showed as inhibitors of the metabolic activations of neutrophils, although the degree was dependent on the drug concentrations. The order of potency of the inhibitory effects on the arachidonic acid release were: homochlorcyclizine, clemastine, and azelastine (IC50 less than 20 microM) greater than oxatomide (IC50 less than 60 microM) and diphenylpyraline greater than triprolidine, meclizine, diphenhydramine (IC50 greater than 100 microM). The superoxide generation from neutrophils activated by phorbol 12-myristate 13-acetate was also effectively inhibited by these agents, but generally lower concentrations were required to obtain the same degrees of effects. These results indicated that some of the histamine H1 receptor-blocking drugs, such as clemastine and homochlorcyclizine, may act as inhibitors of formation of leukotrienes at the locus of inflammation.

Arachidonic Acid↗

PubMed1991

Synthesis and biological activity of 11-[4-(cinnamyl)-1-piperazinyl]- 6,11-dihydrodibenz[b,e]oxepin derivatives, potential agents for the treatment of cerebrovascular disorders.

A series of 11-[4-(cinnamyl)-1-piperazinyl]-6,11-dihydrodibenz[b,e] oxepins and related compounds were synthesized and evaluated for their protective activities against complete ischemia, normobaric hypoxia, lipidperoxidation and convulsion. Structure-activity relationship studies of this series led to the finding of (E)-1-(3-fluoro-6,11-dihydrodibenz[b,e]oxepin-11-yl)-4-(3- phenyl-2-propenyl)piperazine dimaleate (50), AJ-3941 with the most appropriate property for combined pharmacological activities. Compound 50 also shows an inhibitory effect against cerebral edema as well when orally given to rats.

Animals↗

PubMed1991

[Catecholamine secretion from adrenal chromaffin cells].

The effect of palytoxin (PTX) on catecholamine (CA) secretion from cultured bovine adrenal chromaffin cells was examined. PTX (greater than 10(-10) M) induced CA secretion concentration-dependently. About 40-50% of the total cellular CA was secreted during a 20 min incubation with 3 x 10(-8) M PTX. PTX caused increases in [22Na](+)- and [45Ca](2+)-influxes into the cells, which were not affected by TTX. PTX-induced CA secretion and [22Na](+)- and [45Ca](2+)-influxes were significantly inhibited by quinidine and aprindine, antiarrhythmic drugs. Ca(2+)-channel blockers such as nifedipine, verapamil, Co2+, and Cd2+ inhibited both CA secretion and [45Ca](2+)-influx induced by PTX. These results indicated that PTX-induced CA secretion was mediated by activation of Na(+)-dependent, TTX-insensitive voltage-dependent Ca(2+)-channels. PTX-induced [22Na](+)-influx was inhibited by amiloride, an inhibitor of the Na(+)-H+ exchange system, suggesting that the Na(+)-H+ exchange mechanism might be involved in PTX-induced [22Na](+)-influx into the cells. The effects of flavonoids on CA secretion from permeabilized adrenal chromaffin cells were examined. CA secretion from the cells in response to a direct Ca2+ challenge was inhibited by quercetin (greater than 10(-5) M) and apigenin (greater than 10(-5) M). These flavonoids also inhibited phorbol ester TPA-induced CA secretion. Therefore, the inhibitory effects of flavonoids on CA secretion were thought to be attributed to their inhibitory effects on PKC.

Acrylamides↗