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Biomedical subjects

Y Hara

Publications and source records attributed to Y Hara.

At least 613 records · Page 34Linked to original sources
PubMed1988

Auto-anti-idiotype antibody against anti-thyroglobulin auto-antibody in humans.

Anti-idiotype antibodies (Anti-Id Ab) are believed to normally exert a form of feedback control on Ab production. An abnormality in this network might lead to excess Ab production. To detect the abnormalities in immunoregulation in autoimmune thyroid disease, we tried to demonstrate anti-Id Ab to anti-thyroglobulin antibody (ATA) and to correlate them to the clinical course of disease. We developed two assays, one based on the binding of anti-Id Ab to ATA (Id) and a second on the inhibitory activity of anti-Id Ab in the reaction of human thyroglobulin (hTG) and ATA. We could not demonstrate anti-Id Ab in either assay. Possibly anti-Id Ab to ATA is not formed sufficiently to be detected in our assays, or is only present in specific phases of the course of autoimmune thyroid disease. During studies of anti-Id Ab we found "pepsin site" Ab in patients and normal subjects. We developed a new solid phase radioimmune assay for this Ab, an antibody which reacts with antigens exposed on IgG when F(ab')2 fragments of IgG are prepared. The incidence of this Ab did not differ between patients and normal subjects. IgG from patients with autoimmune thyroid disease which contained high levels of anti-pepsin site Ab, did not show any specificity for ATA (Id), nor did it inhibit the reaction between hTG (Ag) and ATA (Id). The importance of this anti-F(ab')2 antibody remains to be determined, but it does not represent an anti-Id Ab.

Antibodies, Anti-Idiotypic↗
PubMed1988

T-cell-derived factor B151-TRF1/IL-5 activates blastoid cells among unprimed B cells to induce a polyclonal differentiation into immunoglobulin M-secreting cells.

Two distinct murine B-cell differentiation factors, designated B151-TRF1 and B151-TRF2, were described originally as B151K12 T-cell hybridoma-derived lymphokines that induce immunoglobulin (Ig) secretion by antigen-activated B cells and unstimulated B cells, respectively. In the present study, we found that a highly purified B151-TRF1 fraction prepared by reversed-phase high-performance liquid chromatography (RP-HPLC) also has the ability to cause a polyclonal differentiation of unstimulated B cells into IgM-secreting cells in the apparent absence of co-stimulant. The activity of the B151-TRF1 fraction but not the B151-TRF2 fraction on unstimulated B cells was markedly inhibited by addition of a monoclonal antibody (mAb) specific for the B151-TRF1/IL-5 to the culture. To determine whether B151-TRF1/IL-5 and B151-TRF2 act on distinct populations among unstimulated B cells, the responsiveness of neonatal B cells and adult B cells that had been fractionated by Percoll density gradient centrifugation was assessed. B151-TRF1/IL-5 predominantly acted on lower density B cells, which appeared around 3 weeks after birth in the spleen. In contrast, B151-TRF2 could activate both lower and higher density B cells almost equally and B151-TRF2-responsive B cells were already present by 1 week of age. Thus, these results suggest that B151-TRF1/IL-5 and B151-TRF2 act on distinct subpopulations among antigen-unprimed normal B cells to induce IgM-secreting cells.

Animals↗
PubMed1988

MCl-176, a novel calcium channel blocker, attenuates the ischemic myocardial acidosis induced by coronary artery occlusion in dogs.

The effect of MCl-176 [2-(2,5-dimethoxyphenylmethyl)-3-(2-dimethylaminoethyl)-6- isopropoxy-4(3H)-quinazolinone hydrochloride], a novel calcium channel blocker, on ischemic myocardial acidosis was studied in the dog heart, in which the left anterior descending coronary artery was partially occluded for 90 min (partial occlusion). Myocardial pH (measured by a micro glass pH electrode) was about 7.60 in the nonischemic normal heart. The myocardial pH decreased rapidly in response to partial occlusion, and reached the steady state of about 6.85 within 30 min (i.e., the myocardial [H+] increased after partial occlusion). Saline or drug was injected i.v. 30 min after partial occlusion, and the drug effect was observed till the end of partial occlusion. Myocardial [H+], that had been increased by partial occlusion, restored slightly after the saline injection, and the restoration was about 30% 60 min after the injection. MCl-176 increased this spontaneous restoration of myocardial [H+] with a decrease in blood pressure and heart rate; the restoration induced by 0.1 mg/kg of MCl-176 was 74% 60 min after the injection. Even in the paced heart, MCl-176 (0.1 mg/kg) attenuated the ischemia-induced myocardial acidosis. Propranolol (1 mg/kg) also attenuated the myocardial acidosis, the restoration being 82%. These results indicate that MCl-176 attenuates the myocardial acidosis during ischemia as does propranolol, and that the mechanism of action of MCl-176 is not due primarily to a decrease in heart rate.

Acidosis↗
PubMed1987

Accumulation of nonesterified fatty acids in the dog myocardium during coronary artery occlusion determined by a method using 9-anthryldiazomethane.

The levels of nonesterified fatty acids (NEFA) in the myocardium during ischemia were determined by a simple method, which requires neither previous separation with thin-layer chromatography nor heating. After being extracted with Folch's solution, NEFA were subjected to fluorescent labeling with 9-anthryldiazomethane at room temperature, separation with high-pressure liquid chromatography, and then detection by a flow-through fluorometer. Calibration and validation studies revealed that this method was satisfactory. The left anterior descending coronary artery was completely occluded for 90 min in dogs anesthetized with pentobarbital. In the nonischemic myocardium, the levels of lauric, myristic, palmitic, palmitoleic, stearic, oleic, linoleic, and arachidonic acids were 5.31, 15.85, 47.06, 2.59, 23.92, 37.90, 38.69, and 3.99 nmol/g wet tissue, respectively, and those in the ischemic myocardium 5.67, 22.16, 75.94, 6.65, 42.67, 61.75, 70.06, and 13.39 nmol/g wet tissue, respectively, the total NEFA in the former being 175.3 and that in the latter 298.3 nmol/g wet tissue. The increase in myocardial NEFA during ischemia was significant except for lauric and myristic acids, and the increase in arachidonic acid was the greatest. The ratio of the level of arachidonic acid in the ischemic myocardium to that in the nonischemic myocardium was 335.6%.

Animals↗
PubMed1987

Acidosis, not azotemia, stimulates branched-chain, amino acid catabolism in uremic rats.

To investigate branched-chain, amino acid metabolism (BCAA) in muscle in chronic renal failure (CRF), we studied rats with moderately severe uremia (PUN 110 approximately mg/dl) and spontaneous metabolic acidosis (bicarbonate, 19 +/- 1 mEq/liter). Plasma BCAA levels in CRF compared to pair-fed control rats were approximately 15% lower and muscle valine was 93 microM lower (P less than 0.05). BCAA metabolism was measured in incubated epitrochlearis muscles using L-[1-14C]valine or L-[1-14C]leucine in the presence and absence of insulin. BCAA decarboxylation was increased (P less than 0.05) and insulin-stimulated BCAA incorporation into protein was blunted (P less than 0.05) by CRF. Since we have found that metabolic acidosis, by itself, stimulates muscle branched-chain, ketoacid dehydrogenase activity, another group of CRF and control rats was given NaHCO3 which corrected the acidosis, but not the azotemia. BCAA decarboxylation in muscle was reduced in CRF rats given NaHCO3, and this was reflected in increased plasma and muscle BCAA concentrations. We conclude that in CRF, chronic metabolic acidosis stimulates BCAA decarboxylation in skeletal muscle and this could contribute to the reduced intra- and extracellular concentrations of BCAA. Correction of acidosis should be a goal of therapy in CRF, especially when dietary regimens restrict intake of BCAA.

Acidosis↗
PubMed1987

Primary structures of two types of alpha-subunit of rat brain Na+,K+,-ATPase deduced from cDNA sequences.

A rat brain cDNA library was screened by using as a probe a fragment of cDNA encoding the alpha-subunit of human Na+,K+-ATPase. Two different cDNA clones were obtained and analyzed. One of them was concluded to be a cDNA encoding the alpha-subunit of the weakly ouabain-sensitive rat kidney-type Na+,K+-ATPase. The deduced amino acid sequence consists of 1,018 amino acids. The alpha-subunit of the rat kidney-type Na+,K+-ATPase shows 97% homology in amino acid sequence with the alpha-subunit of human, sheep, or pig enzyme and 87% with that of Torpedo. Based on a comparison of the amino acid sequence at the extracellular domain of the alpha-subunit between weakly ouabain-sensitive rat kidney-type enzyme and the ouabain-sensitive human, sheep, pig, or Torpedo enzyme, it was proposed that only two significant amino acid replacements are unique to the rat kidney-type alpha-subunit. Another cDNA clone obtained showed 72% homology in nucleotide sequence with the former cDNA coding the alpha-subunit of the rat kidney-type Na+,K+-ATPase and the deduced amino acid sequence exhibited 85% homology with that of the alpha-subunit of rat kidney-type Na+,K+-ATPase.

Amino Acid Sequence↗
PubMed1987

Comparison of rates of cation release and of conformational change in dog kidney Na, K-ATPase.

1. It is now widely believed that the main rate-limiting step in the sodium-potassium pump (Na, K-ATPase) cycle is a conformational change between two forms of the dephosphoenzyme (E2 and E1) and that this change releases to the cell interior potassium ions occluded within the E2 form. 2. If this hypothesis is correct, and if occluded ions cannot be released directly from dephosphoenzyme in the E2 conformation, we should expect that, under any given conditions, the rate of release of the occluded ions would be identical with the rate of the conformational change. 3. Using the potassium congeners 86Rb, 137Cs and 204Tl, the rates of release of the occluded ions can be measured by a rapid ion-exchange technique. Using the fluorescence probes fluorescein isothiocyanate (FITC), eosin or 5-iodoacetamido-fluorescein (5-IAF), the rates of the conformational change can be measured by stopped-flow fluorimetry. 4. A comparison of the two rates in the absence of ATP showed that the rate of release of the occluded ions was usually somewhat faster than the rate of the fluorescence change. The discrepancy was probably caused by a very slow direct release of occluded ions from enzyme in the E2 form, but we cannot exclude the possibility that it is the result of systematic errors. In the presence of 5 microM-ATP, both rates were increased and there was no significant difference between them. 5. The results are compatible with the hypothesis that the same conformational change alters the fluorescence of the fluorescent probes and releases the occluded potassium congener ions.

Animals↗
PubMed1987

Branched-chain amino acid metabolism in rat muscle: abnormal regulation in acidosis.

Branched-chain amino acid (BCAA) metabolism is frequently abnormal in pathological conditions accompanied by chronic metabolic acidosis. To study how metabolic acidosis affects BCAA metabolism in muscle, rats were gavage fed a 14% protein diet with or without 4 mmol NH4Cl X 100 g body wt-1 X day-1. Epitrochlearis muscles were incubated with L-[1-14C]-valine and L-[1-14C]leucine, and rates of decarboxylation, net transamination, and incorporation into muscle protein were measured. Plasma and muscle BCAA levels were lower (P less than 0.05) in acidotic rats. Rates of valine and leucine decarboxylation and net transamination were higher (P less than 0.05) in muscles from acidotic rats; these differences were associated with a 79% increase in the total activity of branched-chain alpha-keto acid dehydrogenase and a 146% increase in the activated form of the enzyme. We conclude that acidosis affects the regulation of BCAA metabolism by enhancing flux through the transaminase and by directly stimulating oxidative catabolism through activation of branched-chain alpha-keto acid dehydrogenase.

3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)↗