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Biomedical subjects

Y Isayama

Publications and source records attributed to Y Isayama.

At least 19 recordsLinked to original sources
PubMed1998

The effect of chronic treatment with trandolapril on cyclic AMP-and cyclic GMP-dependent relaxations in aortic segments of rats with chronic heart failure.

1 Characteristics of cyclic GMP- and cyclic AMP-mediated relaxation in aortic segments of rats with chronic heart failure (CHF) and the effects of chronic treatment with an angiotensin I converting enzyme (ACE) inhibitor, trandolapril, were examined 8 weeks after coronary artery ligation. 2 Cardiac output indices of coronary artery-ligated and sham-operated rats were 125+/-8 and 189+/-10 ml min(-1) kg(-1), respectively (P<0.05), indicating the development of CHF at this period. 3 The maximal relaxant response of aortic segments to 10 microM acetylcholine in rats with CHF and sham-operated rats was 64.0+/-5.7 and 86.9+/-1.9%, respectively (P<0.05), whereas the relaxant response to sodium nitroprusside (SNP) remained unchanged. Tissue cyclic GMP content in rats with CHF was lower than that of sham-operated rats. 4 In endothelium-intact segments of rats with CHF, the maximal relaxant response to 10 microM isoprenaline (44.5+/-6.7%) was lower that sham-operated rats (81.3+/-2.5%, P<0.05) and the concentration-response curve for NKH477, a water-soluble forskolin, was shifted to the right without a reduction in the maximal response. Isoprenaline-induced relaxation of aortic segments was attenuated by NG-nitro-L-arginine methyl ester (L-NAME) in sham-operated rats, but not in rats with CHF. Relaxation to 30 microM dibutyryl cyclic AMP in rats with CHF (26.8+/-2.7%) was lower than that in sham-operated rats (63.4+/-11.8%, P<0.05). 5 Trandolapril (3 mg kg(-1) day(-1)) was orally administered from the 2nd to 8th week after the operation. Aortic blood flow of rats with CHF (38.5+/-3.6 ml min(-1)) was lower than that of sham-operated rats (55.0+/-3.0 ml min(-1)), and this reduction was reversed (54.1+/-3.4 ml min(-1)) by treatment with trandolapril. The diminished responsiveness described above was normalized in the trandolapril-treated rat with CHF (i.e., the maximal relaxation to acetylcholine, 94.7+/-1.0%; that to isoprenaline, 80.5+/-2.8%; that to dibutyryl cyclic AMP, 54.7+/-6.2%). However, aortic segments of trandolapril-treated rats with CHF, L-NAME did not attenuate isoprenaline-induced relaxation and the tissue cyclic GMP level was not fully restored, suggesting that the ability of the endothelium to produce NO was still partially damaged. 6 The results suggest that vasorelaxation in CHF, diminished mainly due to dysfunction in endothelial nitric oxide (NO) production and cyclic AMP-mediated signal transduction, was partially restored by long-term treatment with trandolapril. The mechanism underlying the restoration may be attributed in part to prevention of CHF-induced endothelial dysfunction.

Acetylcholine↗
PubMed1998

Modulation of cAMP-mediated vasorelaxation by endothelial nitric oxide and basal cGMP in vascular smooth muscle.

Recent in vitro evidence shows a role of endothelial nitric oxide (NO) in the modulation of isoproterenol-induced vasorelaxation. To elucidate roles of endothelial cells and NO in cyclic adenosine monophosphate (cAMP)-mediated vasodilators we examined the effects of removal of endothelium and a NO synthase (NOS) inhibitor on relaxant responses in vitro of rat aortic strips to beta-adrenoceptor stimulants and colforsin dapropate, a water-soluble forskolin, and changes in cAMP and cyclic guanosine monophosphate (cGMP) contents. Relaxant responses of rat aorta to isoproterenol, denopamine, salbutamol, colforsin, and dibutyryl cAMP (dbcAMP) were blunted by removal of endothelial cells or treatment with NOS inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME). Relaxant response of endothelium-intact segments to isoproterenol was associated with increases in tissue cAMP and cGMP contents. Removal of endothelium or treatment with L-NAME markedly reduced basal cGMP and abolished the isoproterenol-induced increase in cGMP but not cAMP content. In endothelium-removed segments, pretreatment with sodium nitroprusside (SNP) restored the diminished relaxant response to isoproterenol and increased basal cGMP (from 0.08 +/- 0.01 to 0.16 +/- 0.02 pmol/mg protein), whereas it did not affect the isoproterenol-induced increase in cAMP. The diminished relaxant response of endothelium-removed segments to dbcAMP was not restored by SNP pretreatment. The results suggest that relaxant response of rat aorta to cAMP-mediated vasodilators is mediated, in part, by NO production in endothelium and subsequent increase in cGMP in vascular smooth-muscle cells.

Adrenergic beta-Agonists↗
PubMed1997

beta-Adrenoreceptor antagonistic actions and mutagenicities of R(+)- and S(-)-enantiomers of N-desisopropylpropranolol and its N-acetyl conjugate.

Enantiospecific acetyl conjugation was examined in the rat liver 105000 x g supernatant (cytosol) system using racemic 1-amino-3-(1-naphthyloxy)-2-propanol (NDP), a N-desisopropyl metabolite of propranolol. From the results of chiral separative determination of the samples by HPLC using a Chiralcel OD-R column, more remarkable enantiospecificity was observed in the R(+)-enantiomer on NDP elimination and N-acetyl conjugate (AcNDP) formation. Next, the strength of beta-adrenoceptor antagonistic actions and mutagenicities was compared between R(+)- and S(-)-enantiomers of NDP and AcNDP, respectively. In the case of NDP, both enantiomers possessed weak beta1-adrenoceptor antagonistic effects on isoproterenol-induced positive inotropic and chronotropic actions in the left and right atria isolated from a guinea pig. These actions of R(+)- and S(-)-NDP were 1700-times and 100-times less potent, respectively, than those of propranolol. beta2-Adrenoceptor antagonistic actions of R(+)- and S(-)-NDP in the trachea were 1600-times and 200-times less potent, respectively, than those of propranolol. Enantiospecificity was observed in the beta-adrenoceptor antagonistic action of S(-)-NDP, while R(+)-NDP and both enantiomers of AcNDP appeared to be negligible in this action. On the other hand, the mutagenicities of each enantiomer were examined by the Ames method using 13 kinds of Salmonella typhimurium strains. In the case of AcNDP, the numbers of colonies increased according to the substrate concentration only when rat liver 9000 x g supernatant fraction (S-9 mixture) was added to the plates containing TA100, YG1029, TA104 and YG3003, and then enantiospecificity was observed in the mutagenicity of S(-)-AcNDP. Thus, the ultimate mutagen might be an active metabolite formed mainly from S(-)-AcNDP. Despite of the addition of rat liver S-9 mixture, R(+)-AcNDP and both enantiomers of NDP did not indicate mutagenicity.

Adrenergic beta-Antagonists↗
PubMed1997

Crystal violet staining of Bordetella bronchiseptica colonies for differentiation of phase-I strains from variant strains in degraded phases.

After 2 days of growth on Brain heart infusion agar (BHIA) at 38 degrees C, phase-I colonies and degraded-phase colonies of Bordetella bronchiseptica could be differentiated by their ability to take up crystal violet (CV). Phase-I colonies in X mode, but not colonies in degraded phases (phases II, III, and rough) bound CV. Phenotypically-altered C-mode colonies (grown at 32 degrees C or lower temperatures) also lacked this ability. CV staining offers an easy method for the recognition of different colony types that appear identical when observed on BHIA.

Animals↗
PubMed1995

Genotyping of isolates of Taylorella equigenitalis from thoroughbred brood mares in Japan.

Profiles of the genomic DNA of 104 strains of T. equigenitalis isolated from brood mares with contagious equine metritis in Hokkaido during the breeding seasons from 1980 to 1993, as well as those of five strains (SS28, EQ56, EQ59, EQ70 and HH139) previously isolated in Japan were examined after restriction digestion and crossed-field gel electrophoresis. These profiles were essentially identical to each other and the various isolates and strains appeared to have a common genotype, designated 'genotype J', with respect to two restriction enzymes, ApaI and NotI. These results suggest a common source for all these isolates obtained over the course of more than 10 years in Japan.

Animals↗
PubMed1994

Analysis of chromosome-sized DNA and genome typing of isolated strains of Taylorella equigenitalis.

Analysis of chromosome-sized DNA and genome typing of Taylorella equigenitalis NCTC11184, Kentucky 188, and five strains of T. equigenitalis isolated in Japan were carried out. The three restriction enzymes used, ApaI, NaeI and NotI, cleaved the genomic DNAs of five Japanese strains of T. equigenitalis into relatively limited numbers of restriction fragments, which were well resolved on crossed-field gel electrophoresis (CFGE). The respective profiles after CFGE of the restriction fragments from all five strains were essentially identical to each other after digestion by ApaI, NaeI or NotI. Hence it appears that these strains have a common genome type with respect to these three restriction enzymes. It was also shown that the respective profiles from these strains were essentially different from those of T. equigenitalis NCTC11184 and those of Kentucky 188 after digestion with ApaI, NaeI or NotI.

Animals↗
PubMed1994

Serum C-reactive protein and immune responses in dogs inoculated with Bordetella bronchiseptica (phase I cells).

Eight Beagle dogs were inoculated intrabronchially with 5 x 10(9) live, avirulent cells of Bordetella bronchiseptica L-414 strain (phase I cells) (B. bronchiseptica) to investigate the serum levels of their C-reactive protein, the white blood cell counts, the antibody responses to B. bronchiseptica in the sera and tracheal secretions, and the effects of prednisolone given to four of the dogs on C-reactive protein (CRP), white blood cells (WBC) and immune responses. In two Beagle dogs inoculated intrabronchially with sterile physiological saline, the concentrations of CRP and the WBC counts did not increase. CRP was markedly increased one day after inoculation in the dogs inoculated with B. bronchiseptica to 385.0-720.0 micrograms/ml (mean 498 +/- 132 micrograms/ml) in the group given the B. bronchiseptica inoculation only, and to 372.0-649.0 micrograms/ml (mean 551 +/- 106 micrograms/ml) in the group treated with prednisolone following inoculation of B. bronchiseptica, as determined by an enzyme-linked immunosorbent assay (ELISA). The CRP levels were 23-95 times the pre-inoculation values, which indicated that prednisolone had no effect on the production of CRP. In the prednisolone-treated group, the WBC count increased and stayed at an increased level for approximately 12 days. An indirect fluorescent antibody test led to the detection of anti-B. bronchiseptica IgM and IgG antibodies in the sera from 5 days after B. bronchiseptica inoculation and S-IgA and IgG anti-B. bronchiseptica antibodies in the tracheal secretions on the day after the challenge exposure to B. bronchiseptica. The increase in CRP after challenge exposure to B. bronchiseptica was significantly (p < 0.05) smaller than that found after the first inoculation of B. bronchiseptica.

Animals↗
PubMed1994

[Event-related potentials in anisometropic amblyopia].

Event-related potentials were recorded from 20 neurologically normal children with anisometropic amblyopia. Stimulation was performed with an 'odd-ball' paradigm counting Randolts' circle, and in all cases N200 and P300 were recorded as event-related potentials. The latencies of N200 showed statistically significant delay (p < 0.001: Wilcoxson signed rank test), but P100 and P300 were not delayed in the stimulus input from amblyopic eyes. The degree of delay has no relationship with visual acuity or anisometropic differences. The results suggest that the cortical sensory processing functions represented by P300 were not damaged in the amblyopic cases observed in this study.

Amblyopia↗
PubMed1991

[A case of cerebral arteriovenous malformation revealed at repeated subcortical hematoma with initially normal angiogram].

An 18-year-old male admitted to our hospital suffered left temporal subcortical hemorrhage. No abnormality was demonstrated on carotid or vertebral angiography at that time. On the day following the onset, left frontotemporal craniotomy was performed and the subcortical hematoma was evacuated. No vascular malformation was found despite careful investigation. On 30th day after the onset, the repeat cerebral angiography was performed but failed to show any vascular abnormalities. After discharge he was in good health, and had had some follow up, CT were normal except for the hematoma cavity. Just two years after the first operation he suffered a second left temporal hemorrhage. Cerebral angiography was repeated and a temporal arteriovenous malformation (AVM) was found with feeding vessels from the M-1 and M-2 portion of the left middle cerebral artery and from the left anterior choroidal artery, and draining veins to vein of Rosenthal and the straight sinus. One month after the second hemorrhage, left frontotemporal craniotomy was performed and complete excision of the AVM was carried out. Only five cases of AVMs in patients with normal angiograms several years before have been reported previously in the literature. But there are no cases in which surgery has been performed. Differently to those cases, in this case it was investigated operatively whether there was a vascular abnormality at the first hemorrhage. We didn't think, however, that the AVM demonstrated at the second hemorrhage had developed spontaneously because there had been a hemorrhage of unknown origin previous to it. It was assumed that a small angiographically occult AVM connected to the hematoma cavity existed at the time of the first hemorrhage but it was too small to be found even during surgical procedure. Such an angiography occult AVM had been growing for two years, and its growth had probably been facilitated by the presence of the hematoma cavity left after the first operation.

Adult↗
PubMed1990

Hydrophobic surface properties of Bordetella bronchiseptica X-mode cells and their possible role in adherence to porcine nasal mucosa.

Bordetella bronchiseptica strains were examined to determine whether the surface hydrophobicity of the bacteria correlates with their adherence to porcine nasal epithelial cells. The relative hydrophobicity of the bacteria, measured by their retention to a column of hydrophobic phenyl-Sepharose gel and their aggregation in ammonium sulfate solution, correlated well with their adhesive properties. Phase I cells in X-mode, which adhered well to the epithelial cells, were conspicuously hydrophobic. The cells in C-mode and degraded phases, which adhered poorly to the epithelial cells, were relatively hydrophilic. These observations provide evidence for the suspected role of hydrophobic interactions in the adherence of B. bronchiseptica to porcine nasal mucosa.

Animals↗
PubMed1987

Virulence factors in Escherichia coli isolated from piglets with neonatal and post-weaning diarrhea in Japan.

A total of 567 strains of Escherichia coli were isolated from piglets with neonatal diarrhea (ND) or post-weaning diarrhea (PWD) in Japan. They were investigated for enterotoxigenicity and possession of adhesins and O antigens. There were clear differences between the strains of ND origin and those of PWD origin in the occurrence of enterotoxigenic E. coli (ETEC) strains, type of enterotoxin and frequency of adhesins: ETEC was found in 77 (25.7%) of 300 strains of ND origin and in 137 (51.3%) of 267 strains of PWD origin. ETEC strains producing heat-labile enterotoxin (LT) or heat-stable enterotoxin (STa), alone or in combination were evenly distributed among the strains of PWD origin. In contrast most of the ETEC strains of ND origin produced LT alone. Adhesins appeared in 42 (54.5%) of 77 ETEC strains of ND origin and in 36 (26.3%) of 137 ETEC strains of PWD origin. Adhesins were less common in ETEC strains of PWD origin than in those of ND origin. Some K99-positive ETEC strains of PWD origin produced both LT and STa. There was a similarity in the distribution of O antigens, particularly O149 and O157, between the strains of ND origin and those of PWD origin.

Animals↗
PubMed1987

Diagnosis of Rhodococcus equi infection in foals by the agar gel diffusion test with protein antigen.

A protein antigen that reacted in the agar gel diffusion (AGD) test and which had equi factor(s) activity, was partially purified from the culture supernatant of Rhodococcus equi by successive column chromatography on diethylaminoethyl cellulose and Sepharose 4B. Employing a standard foal serum, the concentration of this antigen was adjusted for the AGD test. Optimal dilutions of the antigen reacted in the AGD test with sera from foals naturally infected with serologically different R. equi. The antigen prepared was considered suitable for use in field surveys of R. equi infection. Accordingly, four groups of sera were tested: those from 18 foals diagnosed as being infected with R. equi, those from 54 control foals with culture-negative R. equi pneumonia, arthritis or cellulitis, those from 46 diseased foals suspected of having R. equi infection and those from 51 clinically normal foals. A positive precipitation reaction was observed with sera from 100% of the first group, 69.5% of the third group and 17.7% of the fourth group. A negative reaction was obtained with sera from 100% of the second group.

Actinomycetales Infections↗