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Biomedical subjects

Y Nakamaru

Publications and source records attributed to Y Nakamaru.

32 records · Page 2Linked to original sources
PubMed1996

The association between human leukocyte antigens (HLA) and cytoplasmic-antineutrophil cytoplasmic antibody (cANCA)-positive Wegener's granulomatosis in a Japanese population.

The present study examined the association between various human leukocyte antigens (HLA) and cytoplasmic-antineutrophil cytoplasmic antibody (cANCA)-positive Wegener's granulomatosis (WG) in Japanese subjects to determine whether HLA antigens are involved in the pathogenesis of this disease. The study involved 16 subjects with cANCA-positive WG treated in our department. HLA-typing of the lymphocytes was performed using a lymphocyte microcytotoxicity assay. Of the subjects with cANCA-positive WG, 62.5% (10/16) were positive for HLA-DR9, as compared to 26% of the healthy control subjects. This HLA-DR9 elevation was statistically significant (p < 0.01, Pc < 0.05); we also noted a weaker association between HLA-B55 and cANCA-positive WG (p < 0.05). The results indicate that an association may exist between certain HLA-class allotypes and WG.

Antibodies, Antineutrophil Cytoplasmic↗
PubMed1995

Thy-1 induced on rat endothelium regulates vascular permeability at sites of inflammation.

We investigated the role of surface adhesion molecules on endothelial cells in regulating vascular permeability, in vitro and in vivo. Cultured rat endothelial cells (REC) express Thy-1, intercellular adhesion molecule-1 (ICAM-1), CD44 and RT1A. Permeability of albumin across the REC monolayer increased through the interaction of Thy-1 and anti-Thy-1 mAb, but not through ICAM-1 and anti-ICAM-1, CD44 and anti-CD44, and RT1A and anti-RT1A mAb. This anti-Thy-1-effect was completely inhibited when the calmodulin antagonist W-7 and the protein kinase inhibitor H-7 was combined, while the IL-6-mediated increase in REC permeability was blocked by either W-7 or H-7, independently. The anti-Thy-1-mediated permeability increase was additively augmented when IL-6 was admixed. These data suggest that intracellular signaling pathways of anti-Thy-1- and IL-6-mediated permeability regulation may be overlapping to some extent but are largely independent. As anti-Thy-1-treatment generated rearrangement of vimentin filaments within REC, alteration of the cytoskeleton distribution may possibly correlate with the regulation of permeability. Although Thy-1-expression on rat vascular endothelium in vivo was not evident, it was induced at sites of Freund's complete adjuvant-induced dermatitis. The administered anti-Thy-1 mAb exclusively located on vascular endothelial surface at the sites of inflammation. Vascular permeability in inflamed skin tissues was significantly augmented when anti-Thy-1 but not anti-ICAM-1, anti-CD44 or anti-RT1A mAb was administered i.v., without affecting populations of inflammatory cells. The collective evidence suggests that Thy-1 induced on rat endothelium is one important regulatory event in vascular permeability at sites of inflammation.

Animals↗
PubMed1994

[The effect of induction chemotherapy with CBDCA, 5-FU and UFT in head and neck cancer].

Induction chemotherapy of low-dose CBDCA, 120-hour continuous infusion 5-FU and UFT was applied to 22 patients with untreated head and neck cancer. CBDCA 75 mg/m2 was given on day 1 and, subsequently, 5-FU 1,500 mg/m2/day for 120-hour continuous infusion was started. UFT was administered every day orally at 400-600 mg/day as biochemical modulation. If tumors were reduced and side effects were mild, these schedules were repeated after two weeks. Three patients (14%) achieved a CR and 11 (50%) a PR, for an overall response rate of 64%. Anorexia, nausea, vomiting and stomatitis were the predominant toxicities. They were mild and well tolerable, although severe diarrhea was observed in one case. Good general conditions of patients were kept because of low grade of toxicities. They were important factors for the tolerance of subsequent radiotherapy and surgery. Based on these results, we conclude that the combination of low-dose CBDCA, 5-FU and UFT as biochemical modulation is effective in head and neck cancer.

Administration, Oral↗
PubMed1982

Specific association of bromocresol purple anions with a magnesium complex of a phosphorylated intermediate during steady-state hydrolysis of ATP by the Mg2+ + Ca2+-dependent ATPase of sarcoplasmic reticulum.

The mechanism of dimeric binding of bromocresol purple (BCP) anions to Mg2+ + Ca2+-ATPase of the sarcoplasmic reticulum (SR) and the resulting partial inhibition of the ATPase activity were studied. BCP anions in three states, free monomer, bound monomer, and bound dimer, were spectrophotometrically calculated by solving simultaneous equations, delta A lambda 1-lambda 2 = sigma delta ai (epsilon i lambda 1-epsilon i lambda 2), and concentration changes of these states were analyzed. The addition of ATP caused an increase in the bound dimer and a decrease in the free monomer, but the change of the bound monomer was slight. The decrease in delta A (decrease phase) on the addition of ATP on dual-wavelength spectrophotometry at 585-610 nm was related to an increase in the amount of dimer bound to the SR membranes. The magnitude of the decrease phase increased with an increase in Mg2+ concentration and decreased with an increase in the concentration of Ca2+. BCP anions at the probe concentration partially inhibited the ATPase activity, and brought about a decrease in the ADP-sensitive E-P (E1P) and an increase in the ADP-insensitive E-P (E2P), though BCP anions did not affect the amount of total E-P. On elimination of Mg2+ at the steady-state E-P level both E2P and E2P . (BCP)2 were decomposed, suggesting that the enzyme form binding the BCP dimer was Mg . E-P. An increase in Mg2+ concentration increased E2P but an increase in Ca2+ concentration decreased E2P. Decomposition of E2P to P1 was inhibited by BCP anions. The following simple scheme was suggested to explain the partial inhibition of the ATPase activity, (Formula: see text). Application of BCP anions was discussed for use as a probe for Mg . E-P in the steady-state ATP hydrolysis.

Adenosine Triphosphate↗
PubMed1977

Two types of sarcoplasmic reticulum-orthophosphate interactions observed with dye probe.

The interaction of Pi with sarcoplasmic reticulum (SR) isolated from rabbit skeletal muscle was studied using bromocresol purple (BCP) as a probe and a dual-wavelength spectrophotometer. Two kinds of absorption-intensity changes controlled by a low concentration of Ca2+ (greater than 10(-6)M) were observed after addition of Pi; an increase phase (in the presence of Ca2+), and a decrease phase (in the presence of EGTA). The increase phase was rapid, Ca2+-dependent, Mg2+-enhanced (depressed by high Mg2+ concentration) and not inhibited by PCMB and was suggested to reflect the formation of an SR-Pi complex. The decrease phase was slower than the increase phase, and was strongly inhibited by the low concentration of Ca2+. It required Mg2+, and was completely inhibited by p-chloromercuribenzoate or deoxycholate. It was suggested to reflect the formation of SR-Pi (phosphorylated protein). ATP inhibited this phase by converting it completely to an SR-MgATP phase. PPi was effective for inducing the decrease phase but PPPi was not. From measurements of these phases, the association constants of the SR-Pi complex and SR-Pi at pH 8.8 in the reaction scheme, SR + Pi in equilibrium SR-Pi in equilibrium SR-Pi, were calculated as 5.4 X 10 M-1 and 1.8 X 10(3) M-1, respectively. From the completely different responses of SR-Pi and SR-Pi observed with BCP a marked difference in the conformations of these enzyme states was suggested.

Adenosine Triphosphate↗
PubMed1977

Dimer formation of bromocresol purple anions on the phosphorylated intermediate of sarcoplasmic reticulum.

The mechanism of spectral shift and absorption intensity change of the divalent bromocresol purple (BCP) anion was further investigated and it was characterized as a spectrophotometric membrane probe. At high concentrations (1-40 mM), the absorption intensity of th BCP anion at 590 nm (monomer band) decreased markedly with increase of the dye concentration, while another absorption band appeared at 554 nm. Analysis of the change of absorption intensity showed that the mared decrease resulted from dimer formation of BCP (polymer formation at concentrations higher than 20 mM). Wavelengths of maximum absorption (lambdamax) of the BCP anion were determined in various solvents and comparison of these lambdamax's with lambdamax of the BCP anion bound to SR showed that the hydrophobicity of the area of BCP anion binding to SR corresponded to a refractive index of 1.429. While the BCP anion bound to SR showed a monomer spectrum, a dimer band appeared for the BCP anion bound to SR-Pi (phosphorylated protein) with a marked decrease in the absorption intensity at the monomer band, indicating that two polar groups, binding sites for the BCP anions, closely approached each other in the SR-Pi configuration.

Animals↗
PubMed1976

Determination of the intravesicular pH of fragmented sarcoplasmic reticulum with 5,5-dimethyl-2,4-oxazolidinedione.

The intravesicular pH (pHi) of fragmented sarcoplasmic reticulum (SR) of the skeletal muscle was determined from the distribution of 5,5-dimethyl-2,4-oxazolidinedione (DMO), a weak organic acid, between the intra- and extravesicular spaces. The pHi's thus obtained were found to be slightly lower (0.02-0.17 pH unit) than the pH's of the external medium (pHe) at pH 6.5-8.5 in the presence of 105 mM KCl and 40 mM Tris-maleate buffer. The higher the pHe, the greater the pH gradient. When pHe was changed, pHi attained equilibrium within about 20 min, the time necessary for the separation of the SR by centrifugation. When 0.25 M sucrose and 5 mM Tris-maleate buffer were used instead of 105 mM KCl and 40 mM buffer, the pH gradient increased to 0.56. It was also demonstrated by direct measurements of pHe with a glass-electrode pH meter that K+ ions added to the external medium exchanged the intravesicular H+ ions. From these results it appears that the pH gradient across the SR membrane was at the Donnan equilibrium. In this state, the Donnan potentials corresponding to pH gradients of 0.17 and 0.56 were -9.3 and -30.6 mV, respectively.

Binding Sites↗
PubMed1972

The influence of hydrogen ion concentration on calcium binding and release by skeletal muscle sarcoplasmic reticulum.

Calcium release and binding produced by alterations in pH were investigated in isolated sarcoplasmic reticulum (SR) from skeletal muscle. When the pH was abruptly increased from 6.46 to 7.82, after calcium loading for 30 sec, 80-90 nanomoles (nmole) of calcium/mg protein were released. When the pH was abruptly decreased from 7.56 to 6.46, after calcium loading for 30 sec, 25-30 nmole of calcium/mg protein were rebound. The calcium release process was shown to be a function of pH change: 57 nmole of calcium were released per 1 pH unit change per mg protein. The amount of adenosine triphosphate (ATP) bound to the SR was not altered by the pH changes. The release phenomenon was not due to alteration of ATP concentration by the increased pH. Native actomyosin was combined with SR in order to study the effectiveness of calcium release from the SR by pH change in inducing super-precipitation of actomyosin. It was found that SR, in an amount high enough to inhibit superprecipitation at pH 6.5, did not prevent the process when the pH was suddenly increased to 7.3, indicating that the affinity of SR for calcium depends specifically on pH. These data suggest the possible participation of hydrogen ion concentration in excitation-contraction coupling.

Actomyosin↗