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Biomedical subjects

Y Oda

Publications and source records attributed to Y Oda.

At least 685 records · Page 38Linked to original sources
PubMed1981

Effects of a transfusion with a blood substitute (Fluosol-DA, 20%) on cerebral circulation in the monkey.

Local cerebral blood flow (lCBF) and electroencephalogram were monitored in six monkeys after a transfusion using a perfluorochemical suspension (Fluosol-DA, 20%) that has been manufactured as a blood substitute and is known to be synthetic, biologically inert, and nontoxic and to have a high capacity for carrying oxygen. The animals were mechanically ventilated, and blood gases were maintained at physiological levels. Fluosol-DA, 20% was administered either by an exchange transfusion of 20 ml/kg or by an infusion of 8 ml/kg followed by an exchange transfusion of 12 ml/kg. lCBF was measured using the hydrogen clearance technique. An equation was proposed to estimate the tissue-blood partition coefficient of hydrogen; this coefficient is considered to be dependent upon the amount of perfluorochemicals in the blood and was used to calculate lCBF. Systemic blood pressure, pulse rate, central venous pressure, electroencephalogram, and gas analysis of the blood from the femoral artery, the femoral vein, and the superior sagittal sinus showed little change throughout the experiment. lCBF was increased by 12% (p less than 0.005) after the infusion of Fluosol-DA, 20% of 8 ml/kg and by 31% (p less than 0.02) after the exchange transfusion. Hyperventilation reduced lCBF significantly (p less than 0.005), which implies that the reactivity of the cerebral blood vessels to hypocarbia was not impaired by the administration of FLuosol-DA, 20%. Both the results of this study and the physical properties of Fluosol-DA, 20% suggest that this blood substitute can safely be used for normal human brains and that it might also be effective for ischemic brains.

Animals↗
PubMed1981

Studies on the specific interaction of concanavalin A and saccharides by affinity chromatography. Application of quantitative affinity chromatography to a multivalent system.

Quantitative affinity chromatography of concanavalin A (Con A) was studied in order to clarify its mechanism of saccharide binding. Another aim of this work was to confirm the validity of frontal affinity chromatography, which we have developed for the study of specific interactions, for multivalent systems. Since Cona A exists as either a dimer or a tetramer, it is a suitable multivalent test system. Immobilized p-aminophenyl-beta-D-glucopyranoside (AP beta-Glc Sepharose) was prepared and the interactions of homogeneous preparations of Con A with this affinity adsorbent were analyzed. Experiments were carried out under conditions where Con a exists as the dimer (5 degrees C, pH 7.9, I=0.19). The intrinsic dissociation constant of Con A for the immobilized ligand (Kd) could be determined from the extent of retardation. alpha-Con A (intact Con A) had a stronger affinity than beta-Con A. Changes in pH and ionic strength had different effects on the affinity of alpha- and beta-Con A. The dissociation constants of soluble saccharides and their derivatives (counter ligands) for Con A (K1) could be determined from their ability to diminish the elution volume of Con A. K1 values of various monosaccharides for beta-Con A including those having very weak affinity, were determined. Further, the K1 values of a series of glucobioses were determined and compared. It was found that the binding mode of the reducing terminal glucose residue must be taken into account. The results are discussed in relation to their configurations. Frontal affinity chromatography proved to be very useful as a tool to analyze specific interactions in multivalent systems.

Carbohydrates↗
PubMed1981

Effects of branched chain fatty acids of iso-C12:0 to iso-C16:0 on gastric secretion and experimental ulceration in rats.

We examined the inhibitory activities of branched-chain fatty acids of iso-C12:0 to iso-C16:0 on gastric secretion in rats. Consequently, iso-C13:0 and iso-C15:0 were found to have strong inhibitory activities on gastric secretion in rats. In the case of intraduodenal administration, iso-C15:0 also showed a significant inhibition of gastric juice secretion. Therefore, the effects of iso-C13:0 and iso-C15:0 on ulceration in pylorus-ligated rats and aspirin-induced ulcer were examined. At the doses of 10 and 25 mg/kg, iso-C13:0 and iso-C15:0 significantly decreased the ulcer index in pylorus-ligated rats, and aspirin-induced ulcer was also significantly inhibited at the doses of 25 and 50 mg/kg. Finally, effect of iso-C15:0 on pepsin, Mg++-ATPase and carbonic anhydrase, which are considered to play an important role in the mechanism of gastric juice secretion, was examined in vitro, centering around iso-C15:0 which showed a marked effect in gastric juice secretion inhibitory and anti-ulcerogenic activities. Iso-C15:0 showed inhibitory activity on pepsin and Mg++-ATPase, but entirely no activity on inhibiting carbonic anhydrase.

Adenosine Triphosphatases↗
PubMed1981

Classical conditioning mediated by the red nucleus in the cat.

We have attempted to develop a behavioral and neuronal model for classical conditioning in the corticorubrospinal system. A conditioned stimulus (CS) was applied to the cerebral peduncle (CP) in cats which had lesions that interrupted the corticofugal fibers caudal to the red nucleus. The unconditioned stimulus (US) was an electric shock to the skin of the forelimb that produced flexion of the limb. After pairing of the CS and US in close temporal association, an initially ineffective stimulus to the cerebral peduncle was found to give rise to the flexion of the elbow. Extinction of the conditioned response was achieved by applying the CS alone or by reversing the sequence of the stimuli (US-CS: backward pairing). Furthermore, the US alone did not produce an increase in the effectiveness of the CS stimulus. Finally, pairing the fixed CS stimuli with the US at random intervals did not produce any increase in performance in response to the CS. In these respects, the observed behavioral modification has the features of associative conditioning. Because the thresholds for and the strength of elbow flexion induced by stimulation of the nucleus interpositus of the cerebellum were identical in the experimental and control animals, the interpositorubrospinal system cannot be the site of the plastic change. Since the conditioned response is most probably mediated by the corticorubrospinal system, it is likely that a modification of the corticorubral synapses underlies this behavioral change.

Animals↗
PubMed1980

Plasma levels of vitamin D metabolites in renal diseases.

Plasma levels of 25-OH-D, 1,25-(OH)2-D and 24,25-(OH)2-D in acute renal failure, chronic glomerulonephritis and chronic renal failure were determined by competitive protein binding assay and evaluated for the correlation with the degree of renal impairment and the influence of dialysis, renal transplantation and the administration of vitamin D and 1-alpha-OH-D3. In this study it is revealed that 25-OH-D deficiency could be normalized by the administration of vitamin D2. Plasma levels of 1,25-(OH)2-D are decreased in proportion to the degree of renal impairment and it is clearly depressed in patients, with a Ccr of 30 ml/min or less. Although biosynthesis of 24,25-(OH)2-D is not remarkably depressed, it is necessary to resolve various questions including the methods of measurement in this respect. It is also disclosed in the present study that 1-alpha-OH-D3 is faster in action than vitamin D2 when used to correct 1,25-(OH)2-D3 deficiency.

Acute Kidney Injury↗
PubMed1979

Spectroscopic and catalytic properties of Rhus vernicifera laccase depleted in type 2 copper.

1. The type 2 copper in Rhus vernicifera laccase was completely removed without loss of other types of copper. The properties of this protein derivative and the role of type 2 copper in the catalytic action of laccase was investigated. 2. The molar extinction coefficient at 614 nm of the blue chromophore decreases from 5700 to 4700 cm-1 on removal of type 2 copper. There are no apparent absorption changes at other wavelengths in the visible or near ultraviolet region when this copper is taken away. The electron-paramagnetic-resonance (epr) parameter A parallel and the linewidth of type 1 Cu2+ decreases on removal of type 2 copper. 3. The rate of reduction of type 1 Cu2+ is not affected by removal of type 2 copper but the reduction of the two-electron acceptor is greatly impaired. These results strongly support the idea that type 1 Cu2+ is the primary site for electron transfer between substrate and enzyme and that the two-electron acceptor in the native enzyme is reduced by simultaneous electron transfer from reduced types 1 and 2 copper. 4. Reoxidation of types 1 and 3 copper and the formation of the oxygen intermediate are the same processes in native and type-2-depleted enzyme. These observations suggests that type 2 copper is not involved in the formation and rapid decay of the oxygen intermediate and that it is not necessary for the stabilization of this intermediate. 5. Two new epr signals are observed on reoxidation of reduced type-2-depleted laccase. One is temporarily formed on re-reduction of reoxidized enzyme and it is suggested that it might arise from copper, possibly type 3 copper. The other one is stable for hours and it is proposed that it might come from a modified oxygen intermediate.

Anaerobiosis↗