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Biomedical subjects

Y Masuda

Publications and source records attributed to Y Masuda.

At least 433 records · Page 24Linked to original sources
PubMed1994

Rapid HPLC assay with coulometric detection for norepinephrine and 3-methoxy-4-hydroxyphenylglycol in the mouse brain.

For the rapid assay of norepinephrine (NE) and its major metabolite, 3-methoxy-4-hydroxyphenylglycol (MHPG) in the mouse brain, we developed a simple method using isocratic HPLC with coulometric detection. This method permits NE and MHPG assay within 5 min in one chromatographic run. Within-run coefficients of variation for NE and MHPG in the working standard solution were 0.8% and 0.6% (n = 50), respectively. The detector responses were linear from 0.025 to 100 pmol for NE and from 0.05 to 100 pmol for MHPG in the working standard solution. Using this method, the NE and MHPG concentrations were measured in discrete brain areas of the mouse prior treatment with or without alpha-methyl-p-tyrosine or N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP4).

Adrenergic Agents↗
PubMed1994

Monoclonal B cells and restricted oligoclonal T cells in T-cell-rich B-cell lymphoma.

Immunophenotyping of lymphoma using paraffin-embedded lymphoid tissue is useful in identifying the large neoplastic B cells in T-cell-rich B-cell lymphoma (TRBL), but does not succeed in deciding clonality. We studied six cases to determine the clonal population of B and T cells of TRBL. Immunohistochemistry on frozen and paraffin-embedded material showed that the cellular population in all six cases consisted mainly of T cells; fewer than ten percent of the cells stained as B cells. However, in all cases, monoclonality of the immunoglobulin was helpful for diagnosing the B-cell neoplasia. Southern blot-yielded genetic analysis showed monoclonality of B cells in three cases, but no evidence of clonality in the T cells. Moreover, gene monoclonality has been detected in all cases examined by polymerase chain reaction, using the primers for the V and J regions of the immunoglobulin heavy chain gene. For T cells, the D and J regions of the T-cell receptor (TCR) beta chain showed the same patterns of oligoclonal bands in all cells, and the V and J regions of the TCR gamma chain showed the same bands in all. The expression of TCR V beta families was polyclonal but restricted.

Aged↗
PubMed1994

Magnetic resonance imaging for aspirated peanut in the bronchus.

Peanut inhalation in the right main bronchus of a 15-month-old boy was diagnosed using a T1-weighted image produced by magnetic resonance imaging (MRI) because of the high fat content of the peanut. The T1-weighted MRI image may also be useful in diagnosing other kinds of aspirated nuts with high lipid content as well as peanuts. This method does not involve any X-ray exposure.

Arachis↗
PubMed1994

Potassium channel openers relax A23187-induced nifedipine-resistant contraction of rat aorta.

We investigated the vasorelaxant mechanisms of three potassium channel openers (PCOs: NIP-121, cromakalim, and nicorandil) using rat aortic strips precontracted with calcium ionophore A23187. A23187 (10(-6) M)-induced contraction was fully relaxed by NIP-121, cromakalim, and nicorandil, but not by the calcium channel blocker nifedipine. The effective concentration range and potency of these relaxant effects were the same as those previously reported for relaxation caused by potassium channel opening in the presence of 30 mM K+ or for relaxation of agonist-induced contraction. Relaxation induced by NIP-121 or cromakalim was competitively antagonized by glibenclamide, with apparent pA2 values for NIP-121 and cromakalim of 7.28 and 7.47, respectively. However, these PCOs did not relax A23187-induced contraction in the presence of 50 mM K+ and 10(-6) M nifedipine. These PCOs but not nifedipine significantly inhibited calcium-induced contraction in the presence of A23187 (10(-6)M). NIP-121, cromakalim, and nicorandil induced full relaxation of A23187-precontracted arteries, which might be attributable (partially for nicorandil) to their potassium channel opening activity. This relaxant effect might be related to inhibition of A23187-induced calcium influx resulting from opening of glibenclamide-sensitive potassium channels.

Animals↗
PubMed1994

Selective inhibitory effect of bufalin on growth of human tumor cells in vitro: association with the induction of apoptosis in leukemia HL-60 cells.

We found that bufalin, an active principle of the Chinese medicine chan'su, has selective inhibitory effects on the growth of various human cancer cells. In order to examine whether the growth-inhibitory effect of bufalin on human cancer cells is associated with apoptosis, human leukemia cells were treated with bufalin. HL-60, ML1, and U937 leukemia cells treated with bufalin at 10(-8) M and above had condensed and fragmented nuclei. Flow cytometric analysis of these cells treated with bufalin showed fragmented DNA smaller than that of the G1 phase. DNA of HL-60 cells treated with bufalin showed a ladder pattern characteristic of apoptosis, as analyzed by agarose gel electrophoretic analysis. DNA synthesis and topoisomerase II activity of HL-60 cells were markedly inhibited as the concentration of bufalin was increased. The concentration needed for inducing apoptosis of HL-60 cells was 10(-8) M, which is comparable to that of camptothecin, but lower than those of other antitumor drugs such as cisplatin, VP16 and all-trans retinoic acid. Apoptosis was not observed when human mononuclear and polymorphonuclear cells were treated with 10(-6) M bufalin for 24 h. These results indicate the association of the growth-inhibitory effect of bufalin with the induction of apoptosis, at least in HL-60 cells, and suggest the usefulness of bufalin for differentiation-apoptosis-inducing therapy for cancer.

Antineoplastic Agents↗
PubMed1994

Heterogeneity of Epstein-Barr virus infection in angioimmunoblastic lymphadenopathy type T-cell lymphoma.

To investigate the relationship of Epstein-Barr virus (EBV) and angioimmunoblastic lymphadenopathy with dysproteinemia, we performed DNA analysis using the polymerase chain reaction (PCR), Southern blot, in situ hybridization, and immunohistochemical analysis of lymph nodes in five patients who were followed up and biopsied more than once. In the course of the disease, nodal architecture diminished, cellular atypia worsened, and clear cells increased in number. In the DNA analysis of the receptor genes, the clonal population increased in number. EBV nucleic acid sequences were found by either PCR or in situ hybridization in all examined nodes. The number of EBV-positive cells varied widely among the cases and throughout the course of the disease in the same patients. The analysis of EBV terminal repeats or lymphocyte-determined membrane antigen genes showed polyclonal populations of EB-infected cells. EBV-positive cells possessed intermediate- to large-sized nuclei, and the cells with large nuclei, especially, expressed latent membrane protein of EBV. These large cells varied among the cases. Double-labelling immunohistochemistry/in situ hybridization studies demonstrated that most of the EBV-positive cells expressed B-cell antigen (CD20). The presence of EBV seems to be associated with the selective defects of the immune system, rather than with the direct pathogenesis of angioimmunoblastic lymphadenopathy.

Base Sequence↗
PubMed1994

Population analysis of cellular responses to synthetic peptides of Der p II, a major allergen molecule of Dermatophagoides pteronyssinus, in allergic and nonallergic subjects.

Responses of peripheral blood mononuclear cells to synthetic oligopeptides of Der p II, one of the major allergen molecules of Dermatophagoides pteronyssinus, were compared between allergic and nonallergic subjects. Healthy subjects showed positive responses to crude extracts of D. pteronyssinus, but only allergic subjects showed elevated cellular responses to Der p II. We synthesized three oligopeptides of Der p II in which motifs of a possible T-cell epitope were included. Of 14 subjects with positive response to Der p II, three responded to all three peptides, while five did not respond to any peptide tested. In 11 allergic patients who showed positive response to Der p II, responsiveness to the peptide K33-T47 was significantly higher than that to other peptides (P < 0.05). All the responding patients were also positive for scratch test to Der p II, suggesting that those epitopes induced IgE-promoting helper T-cell response in allergic persons. On the other hand, the in vitro cellular responses were not necessarily correlated to IgE production against Der p II in healthy subjects.

Adolescent↗
PubMed1994

Mapping and disruption of the chpB locus in Escherichia coli.

The chpB locus is a chromosomal homolog of the pem locus, which is responsible for stable maintenance of plasmid R100 within the host cells. Like pem, chpB codes for two genes, chpBK and chpBI, encoding a growth inhibitor and a suppressor for the killing action of the ChpBK protein, respectively. Here, we determined the precise location of the chpB locus, which is linked to ileR and ppa in the order ileR-chpB-ppa, at 95.7 min on the map of Escherichia coli. We then constructed mutants with an insertion of a (cat) fragment within chpBK or chpBI on the E. coli chromosome. These mutants grew normally, indicating that chpB is dispensable for cell growth.

Base Sequence↗
PubMed1994

Effect of some peptidase inhibitors on exogenous and endogenous opioid actions in guinea-pig ileum.

Met-enkephalin concentration-dependently and transiently inhibited the ileal twitch contraction and this inhibition gradually recovered with time. Bacitracin, phosphoramidon, thiorphan and captopril did not influence the twitch inhibition of met-enkephalin, but bestatin increased the twitch inhibitory potency of met-enkephalin and terminated it in a manner which almost paralleled that of untreated tissue. Transient inhibition of twitch contraction after tetanic stimulation (post-tetanic twitch inhibition) was obtained. Bestatin increased the potency of met-enkephalin and this was terminated within 2 min. Phosphoramidon tended to increase the potency and delayed the termination of post-tetanic twitch inhibition. Bacitracin, thiorphan and captopril did not influence either the potency or the termination of post-tetanic twitch inhibition. Morphine-induced twitch inhibition was not influenced by bacitracin, bestatin or phosphoramidon. These results suggest that bestatin-sensitive aminopeptidase and phosphoramidon-sensitive enkephalinase take part in post-tetanic twitch inhibition, acting in a different mode of action, and have an important role in the termination of the pharmacological action of endogenous opioids (post-tetanic twitch inhibition) in MPLM. This different mode of response of bestatin and phosphoramidon upon post-tetanic twitch inhibition may underlie that aminopeptidase is a more soluble enzyme and enkephalinase is membrane-bound in myenteric plexus-longitudinal muscle (MPLM).

Aminopeptidases↗
PubMed1994

[Effect of efonidipine hydrochloride (NZ-105), a new dihydropyridine calcium antagonist, on the experimental atherosclerosis in cholesterol-fed rabbits].

We studied the effect of efonidipine hydrochloride [NZ-105:(+-)-2-[benzyl(phenyl)amino]ethyl 1,4-dihydro-2,6-dimethyl-5- (5,5-dimethyl-2-oxo-1,3,2-dioxaphosphorinan-2-yl)-4-(3-nitrophenyl )-3-pyridine-carboxylate hydrochloride ethanol], a newly synthesized dihydropyridine calcium antagonist, on atherosclerosis in 1% cholesterol-fed rabbits. NZ-105 (10, 30 and 100 mg/kg) was orally administered to the animals twice a day for 10 weeks. NZ-105 did not cause any significant change in the plasma lipid levels. The area of atherosclerotic lesion was reduced by 37% (P < 0.05) in the aortic arch and by 54% (P > 0.05) in the thoracic aorta of rabbits administrated 100 mg/kg of NZ-105. The content of cholesterol ester in the aorta was also reduced by 64% (P < 0.05) in the aortic arch and by 73% (P > 0.05) in the thoracic aorta. These results suggest that NZ-105 may suppress the development of atherosclerosis without affecting the plasma lipids.

Animals↗
PubMed1994

K(+)-linked release of oxidized glutathione induced by tert-butyl hydroperoxide in perfused rat liver is independent of lipid peroxidation and cell death.

The tert-butyl hydroperoxide (BHP)-induced release of oxidized glutathione (GSSG) and K+ was studied in relation to lipid peroxidation and cell death using isolated perfused rat livers. Infusion of BHP into the perfused liver resulted in an early and simultaneous release of GSSG and K+ and a sustained release of thiobarbituric-acid-reactive substances (TBARS) into the effluent perfusate, which was followed by further prenecrotic leakage of K+ followed by lactic dehydrogenase (LDH). These actions of BHP were not significantly affected by cutting or ligating the bile duct, and they were potentiated by omitting Ca2+ from the perfusion medium. Co-infusion of desferrioxamine, propyl gallate and diethyldithiocarbamate suppressed TBARS release as well as the later leakage of K+ and LDH. Desferrioxamine was also effective under Ca(2+)-free conditions. N,N'-diphenyl-p-phenylenediamine inhibited TBARS release, but it was not protective against cell death, although there was some delay. The action of dithiothreitol was only moderate. On the other hand, leakage of TBARS, K+ (prenecrotic) and LDH was enhanced by cysteamine and beta-mercaptoethanol and most markedly enhanced by ferrous iron. However, none of these agents markedly affected the early release of GSSG and K+. These observations, which support our previous findings, suggest that the early and coupled sinusoidal efflux of GSSG and K+ caused by BHP is independent of lipid peroxidation and cell death and that they represent a physiological mechanism of GSSG release. The results also suggest that lipid peroxidation is not the sole cause of BHP-induced cell death.

Animals↗
PubMed1994

Stimulatory effect of pituitary adenylate cyclase-activating polypeptide on catecholamine synthesis in cultured bovine adrenal chromaffin cells: involvements of tyrosine hydroxylase phosphorylation caused by Ca2+ influx and cAMP.

In cultured bovine adrenal chromaffin cells, pituitary adenylate cylase-activating polypeptide (PACAP) stimulated [14C]catecholamine synthesis from [14C]tyrosine (but not from [14C]DOPA) in a concentration-dependent manner, causing maximal stimulation at 10(-7) M. The stimulatory action of PACAP was not affected by staurosporine (an inhibitor of protein kinase C) or in the cells in which protein kinase C was down-regulated by prolonged exposure to TPA (an activator of protein kinase C), whereas it was partially attenuated in Ca(2+)-free medium. PACAP (10(-7) M) increased the formation of [3H]inositol phosphates, [Ca2+]i and 45Ca2+ uptake as well as cAMP. The peptide also stimulated the phosphorylation of tyrosine hydroxylase, the enzyme catalyzing the rate-limiting step in catecholamine synthesis. Catecholamine synthesis and tyrosine hydroxylase phosphorylation stimulated by the maximal effective concentration of dibutyryl cAMP or high K+, which activates Ca2+ uptake, were further enhanced by PACAP, suggesting that both cAMP- and Ca(2+)-dependent protein kinases may be involved in the stimulation of tyrosine hydroxylase phosphorylation and catecholamine synthesis caused by PACAP.

Adrenal Medulla↗
PubMed1994

Chlorinated and brominated dioxins and dibenzofurans in human tissue following exposure.

With substantial improvements in analytic techniques over the past decade, it has become possible to measure polychlorinated dioxins (PCDDs) and dibenzofurans (PCDFs) in human tissue in a congener-specific fashion down to the low parts per trillion level. This paper reviews findings using these new techniques from a number of recent medical and environmental case studies. These studies include those of workers exposed to a polychlorinated biphenyl (PCB) transformer fire in the United States, German chemical workers exposed to 2,3,7,8-tetrachlorodibenzodioxin (2,3,7,8-TCDD) while cleaning up after an explosion, workers at a municipal incinerator in New York City, a chemist exposed to brominated and chlorinated dioxins, U.S. veterans and also Vietnamese civilians exposed to Agent Orange contaminated with TCDD in Vietnam, and victims of the polychlorinated dibenzofuran and PCB contaminated rice oil (Yusho) incident in Japan.

Adipose Tissue↗
PubMed1994

Polychlorinated biphenyl levels in the tissues of exposed and nonexposed humans.

Polychlorinated biphenyls (PCBs) are synthetic chemicals, manufactured in volume from about 1929 to the 1970s. Environmental contamination by PCBs has been documented in various substances, including human tissue. PCBs have been measured in human tissue by a variety of analytical methods. PCB levels have been reported as an approximation of total PCB content expressed in terms of a commercial mixture, by identification and quantification of chromatographic peaks, or by qualitative and quantitative characterization of specific congeners. Until recently, the coplanar mono-ortho- and di-ortho substituted PCBs, which are especially toxic and present in significant concentration in humans from industrial countries, had not been measured in human tissues. Examples of various types of commonly used analyses are presented in general population subjects and in persons who experienced special exposure. In this paper, the usefulness of PCB blood determinations following potential exposure is demonstrated, and their application in health studies is illustrated from a number of case studies. Coplanar PCB, mono-ortho-substituted and di-ortho-substituted PCB levels in human blood are presented and compared with polychlorinated dioxin (PCDD) and polychlorinated dibenzofuran (PCDF) levels in the U.S. population. Dioxin toxic equivalents for the two groups of chemicals are calculated and compared. It is found that mono-ortho-substituted and, to a lesser extent, coplanar PCBs, contribute substantially to dioxin toxic equivalents (TEq) in blood from U.S. adults. Because of substantial PCB contribution to dioxin toxic equivalents, total dioxinlike toxicity can only be determined if dioxins, dibenzofurans, and dioxinlike PCBs are measured.(ABSTRACT TRUNCATED AT 400 WORDS)

2,4,5-Trichlorophenoxyacetic Acid↗
PubMed1994

Allergens of the house dust mite, Dermatophagoides pteronyssinus, in patients with mite allergic rhinitis: a clinical investigation by intracutaneous skin tests and nasal provocation tests.

To determine the allergens of mite allergic rhinitis, we studied 31 patients with mite allergic rhinitis by skin tests and nasal provocation tests (15 for skin and 16 for nasal tests) using 6 fractions of Dermatophagoides pteronyssinus (Dp) extract differing in molecular weights (15, 25, 32, 53, 95 and 190 kDMW). In skin testing, patients showed intense positive reactions to the fractions of 15, 25, 32, 95 and 190 kDMW, among which the most patients showed positive reactions to the fractions of 15 and 25 kDMW. Significant differences were found in patients' positive reactivity among each fraction and between low (15 and 25 kD) and high (95 and 190 kD) molecular weight fractions as well. In nasal provocation tests, patients showed intense positive reactions to the fractions of 15, 32, 53 and 95 kDMW, especially to the fractions of 15 and 95 kDMW. Furthermore, the insidence of positive reactions to the 15 kDMW fraction was significantly higher than that to any other fraction in the skin tests (P < 0.05). From these results, the low molecular weight fraction, 15 kDMW, is considered to be the main allergen of this mite and the high molecular weight fractions, 95 and 190 kDMW, may also be considered to be allergens of this mite.

Adolescent↗
PubMed1994

Influence of efonidipine hydrochloride, calcium antagonist on the epithelium of prostates in spontaneously hypertensive rats.

The hypertensive effect on the development of the prostatic abnormality in spontaneously hypertensive rats (SHRs) was examined using Efonidipine hydrochloride, a calcium antagonist. The control SHRs were given a high sodium and potassium diet (SP-diet) alone, and the treated SHRs were given a SP-diet with 0.15% Efonidipine hydrochloride from 8 to 28 weeks of age. The systolic blood pressure (SBP) in the control SHRs increased with age, while the elevation of SBP was significantly prevented in the treated SHRs. Light-microscopically, the prostatic lesion was observed both in the control and treated SHRs. The glandular lumen was narrowed with papillary protrusions, and the epithelium was composed of tall columnar epithelial cells. However, hypertension-induced complications in kidneys and hearts were not observed in the treated SHRs. These results suggested that the prostatic abnormality of SHRs might not be the consequent lesions upon hypertension.

Animals↗