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Biomedical subjects

Y Tamura

Publications and source records attributed to Y Tamura.

At least 649 records · Page 36Linked to original sources
PubMed1984

Staphylococcal protein A binding to the Fab fragments of mouse monoclonal antibodies.

Two mouse IgG1 monoclonal antibodies specific for the Lewis(a) human blood group antigen were purified on protein A-Sepharose by using buffers of decreasing pH for elution. Unlike other IgG1 antibodies that eluted at pH 7.0 to 6.0, these antibodies could only be eluted at pH 4.0 to 3.0. The Fab and F(ab')2 fragments of these antibodies also eluted at pH 4.0 to 3.0, although the Fc fragment of one eluted at pH 6.0. This interaction of protein A with Fab was not due to anti-protein A antibody activity, because the presence of Lewis(a) trisaccharide did not prevent the binding of Fab to protein A-Sepharose and because Fab that had bound to solid phase hapten could still be recognized by protein A. Thus, certain mouse IgG1 antibodies possess determinants in their Fab portion recognized by protein A, allowing for the purification of such Fab fragments on protein A-Sepharose.

Animals↗
PubMed1983

Studies on the mechanism of antiaggregatory effect of Moutan Cortex.

The effects of Moutan Cortex and one of its major components, paeonol, on platelet aggregation and arachidonic acid (AA) metabolism in human platelets were studied. One week oral administration of water extract of Moutan Cortex [Moutan Cortex (w), 3 g/day] significantly reduced platelet aggregation and thromboxane B2 (TXB2) formation induced by collagen, epinephrine and ADP. Paeonol dose-dependently inhibited ADP and collagen induced platelet aggregation in vitro. Moutan Cortex (w) and paeonol dose-dependently inhibited the conversion of exogenous [14C]AA to [14C]heptadecatetraenoic acid [( 14C]HHT) and [14C]TXB2 by washed human platelets, while both of them increased its conversion to [14C]12-hydroxy eicosatetraenoic acid [( 14C]12-HETE). High dose of Moutan Cortex (w) inhibited the release of [14C]AA from prelabeled platelets in vitro, while paeonol did not. These results suggest that a reduction in platelet aggregation by the oral administration of Moutan Cortex might be ascribed to a decrease in thromboxane synthesis and that paeonol might play an important role in the antiaggregatory effect of Moutan Cortex because of its potent inhibitory effect on platelet aggregation and thromboxane formation.

Acetophenones↗
PubMed1983

Characterization of monoclonal antibodies specific for the Lewis a human blood group determinant.

Four hybridoma cell lines were derived from the spleen cells of mice immunized with the neutral glycolipids of human meconium. The antibodies secreted by these lines were specific for the Lewis a antigen of the human Lewis blood group system as determined by solid phase immunoassay using synthetic carbohydrate antigens and by plate binding assay and thin layer chromatography-autoradiography using natural glycolipid antigens. Coating protein A-bearing Staphylococcus aureus with one of the antibodies yielded a stable reagent that produced rapid agglutination of Lewis a positive human erythrocytes. The fine structural specificity of these antibodies was assessed by competition radioimmunoassay using synthetic structural analogs of Lewis a conjugated to bovine serum albumin. One antibody was specific for the Lewis a trisaccharide (Gal beta 1 leads to 3(Fuc alpha 1 leads to 4) beta GlcNAc), while a second recognized the entire Lea (1 leads to 3) beta Gal tetrasaccharide. The third and fourth were directed at topography largely provided by only the alpha Fuc and beta GlcNAc units. These monoclonal antibodies not only represent potentially useful reagents for detecting the Lewis a antigen but also provide a system for studying precise relationships between anticarbohydrate antibody structure and binding specificity.

Animals↗
PubMed1983

Decreased glycolipid antigen expression in lymphoma cell variants escaping from anti-glycolipid serotherapy.

Mice challenged with L5178Y lymphoma cells expression high levels of the glycolipid asialo GM2 (gangliotriosylceramide) were protected from tumor growth by passive administration of a monoclonal antibody specific for the glycolipid; in a few antibody-treated mice, ascites cells eventually proliferated which contained a reduced chemical quantity of the glycolipid antigen (3). We now report that the cells emerging from antibody-treated mice had abnormal marker chromosomes identical to those in the cells used for challenge, indicating that the emergent cells were progeny of the challenge inoculum. Flow cytometric analysis revealed that asialo GM2 was undetectable on the surface of greater than 95% of the tumor cells from antibody-treated mice, whereas surface display of H-2 determinants was unchanged from that of the cells used for challenge. Tumor cells arising in challenged but untreated mice consisted of a mixture of asialo GM2-positive and -negative cells, indicating the presence of selective pressures in these mice as well. None of the cells taken from tumor bearing mice differed significantly from the challenge cells in their susceptibility to natural killer cell attack, suggesting that resistance to natural killer cell lysis was not responsible for the proliferation of these cells in vivo. When cells derived from an antibody-treated mouse were used to challenge mice, serotherapy with anti-asialo GM2 had no effect on mouse survival. These results suggest that serotherapy may complement a host anti-tumor response, from which only asialo GM2 deficient cells can escape.

Animals↗
PubMed1983

Chronological relationship between neurological signs and electrophysiological changes in rats with methylmercury poisoning - special reference to selenium protection.

In order to see chronological relationship between electrophysiological changes and "early" neurological sign (tail rotation) elicited in rats poisoned with methylmercury, we made serial measurements of amplitude of compound action potential and sensory nerve conduction velocity of the tail nerve in rats with five dose schedules [methylmercury vs selenium, (1)20 ppm:0.1 ppm, (2)20: 0.3, (3)20: 0.6, (4)10: 0.1, (5)10: 0.6]. We observed the following sequence in the onset of neuro-electro-physiolo-somatic signs: fall in compound action potential greater than decrease in sensory nerve conduction velocity greater than tail rotation greater than weight loss. Protective potency of dietary selenium against neurotoxicity of methylmercury was observed with regard to both electrophysiological changes and neurological signs.

Action Potentials↗
PubMed1983

Effect of oral administration of highly purified eicosapentaenoic acid on platelet function, blood viscosity and red cell deformability in healthy human subjects.

Eicosapentaenoic acid (EPA), which is abundant in seafood, has been reported to be a potent antagonist of platelet aggregation and also to reduce the incidene of cardiovascular disorders. We recently reported that EPA also reduces whole blood viscosity. A highly purified EPA, in a soft capsule (75% ethylester form of EPA; EPA-E), manufactured from sardine oil was administered to 8 healthy male subjects for 4 weeks. No side effects were observed. Platelet aggregation and platelet retention significantly decreased. The EPA content in platelet phospholipids markedly increased but docosahexaenoic acid (DHA) and arachidonic acid (AA) contents did not change. A reduction in whole blood viscosity and an increase in erythrocyte deformability were also observed after 4 week's ingestion of EPA-E. The EPA content in erythrocyte membrane phospholipids markedly increased after 4 weeks, and was positively correlated with erythrocyte deformability. Reduction of platelet aggregation and improvement of the rheological properties of the erythrocyte might be explained by an increase in the EPA content in platelet and erythrocyte phospholipids.

Administration, Oral↗
PubMed1983

Short latency somatosensory evoked potential in children.

The short latency somatosensory evoked potential was studied in 90 normal children of 1 month to 16 years old and 7 adults. Somatosensory stimuli were delivered through a disc electrode placed over the median nerve at the wrist joint. The uniform recording sites used were the central region of the scalp, and the seventh cervical spine or Erb's point. Reference electrodes were placed on the hand contralateral to the median nerve stimulated. Three positive peaks (P1, P2 and P3) and one negative peak (N1) were consistently recorded, a further positive peak (P4) after N1 was not always observed. The latency of each peak per 1 m body length decreased with age until 2 or 5 years of age. The latency of each peak after 2 years of age was positively correlated with the body length and arm length. The value of P1 peak latency per 1 m body length reaches adult values at an earlier rate than the value of P3 peak latency and P2-P3 latency per 1 m body length. This suggests that central lemmiscal pathways mature at a slower rate than peripheral nerve fibers. The wave form pattern of the short latency somatosensory evoked potential changed to the adult pattern at 10 years of age. The peak latency of P4 during deep sleep was slightly prolonged. In recording on infants during sleep, the EEG should be monitored to determine the stage of sleep.

Adolescent↗
PubMed1983

Cyclic adenosine 3', 5'-monophosphate, adenyl cyclase and phosphodiesterase in the conduction system of bovine heart.

Cyclic adenosine 3', 5'-monophosphate (cyclic AMP) and adenyl cyclase and phosphodiesterase activities were determined in the specialized myocardial tissue of the conduction system of bovine heart and then compared with those in the ordinary myocardial tissue. The conduction system was comprised of the atrioventricular node (A-V node), the His bundle and the right and the left bundle branches (RBB and LBB). The content of cyclic AMP was higher in the ordinary myocardial tissue than in the specialized myocardial tissue. In the specialized myocardial tissue, its content was highest in the A-V node and lower in the His bundle than in the LBB and the difference between the contents in the RBB and the LBB was not significant. Adenyl cyclase activity as well as the content of cyclic AMP was higher in the ordinary myocardial tissue than in the specialized myocardial tissue. Its activity was higher in the A-V node than in the His bundle or the RBB, and the activities in the His bundle, the RBB and the LBB were similar. Phosphodiesterase activity was higher in the ordinary myocardial tissue than in the A-V node, and the activities in these 4 sections of the conduction system were similar.

Adenylyl Cyclases↗
PubMed1983

Effects of alcohol diet from the fetal period on lipid metabolism in rats.

The effects of maternal alcohol consumption on lipid metabolism in the litter liver were examined in the rat. Rats reared from their fetal period to adulthood with liquid alcohol diet (fetal alcohol group) did not show any lipid accumulation in the livers. Liver perfusion experiments showed an increased oxygen consumption in the liver to a load of physiological concentration of palmitate. On the contrary, the response of oxygen consumption in fetal control rat livers (reared with non-alcohol liquid diet) to palmitate was found to be depressed. 14CO2 production rate from 14C-palmitate in perfused livers showed a significant increase in fetal alcohol group as compared with controls. No difference in 14C-palmitate incorporation into tissue lipid was found between fetal alcohol and fetal control groups. These data indicate that when rats are treated with alcohol from fetal period they acquire an ability to elevate FFA oxidation in the liver through metabolic adaptation.

Animals↗
PubMed1983

Mechanism of suppressed renin-angiotensin system in spontaneously hypertensive rat (SHR).

Plasma renin concentration (PRC) of SHR decreased with the elevation of blood pressure. In addition in vitro study of basal renin release from kidney slices obtained from SHR produced similar results. However kidney renin activity and total renin content in kidney of SHR were not less than those of Wistar rats. These results indicate that the decreased renin release from kidney might be responsible for the suppression of renin-angiotensin system of SHR after the development of hypertension. Administration of fusaric acid, a dopamine-beta-hydroxylase inhibitor markedly decreased urinary excretion of catecholamine and prostaglandin E in both SHR and Wistar rat and abolished the development of hypertension in SHR. PRC of SHR which became normotensive by fusaric acid administration (normotensive SHR), increased up to the level of control Wistar rats. Therefore suppressed renin-angiotensin system was not observed in normotensive SHR. Nevertheless basal renin release from kidney slices obtained from normotensive SHR was still less than that from control Wistar rats. As urinary catecholamine and prostaglandin E excretion were decreased by fusaric acid administration, these well-known renin stimulators could not be responsible for the reversal of suppressed renin-angiotensin system in normotensive SHR. Rather decreased arterial blood pressure in normotensive SHR lowered renal perfusion pressure, and led to the stimulation of renin release up to the levels of control Wistar rats by the activation of renal arteriolar baroreceptors.

Angiotensin II↗