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Biomedical subjects

T Asakura

Publications and source records attributed to T Asakura.

At least 433 records · Page 24Linked to original sources
PubMed1979

Release of gamma-aminobutyric acid from isolated brain synaptosomes during semicarbazide-induced convulsions.

The in vivo effect of semicarbazide (SC) and aminoxyacetic acid (AOAA) upon gamma-aminobutyric acid (GABA) levels in the synaptosomal fraction, and GABA release from the same fraction were studied in the mouse. The convulsive dose of SC reduced the GABA content in synaptosomes, and when the convulsions were protected by pretreatment with AOAA, the reduced GABA content in synaptosomes rose to or above the normal level. Moreover, the SC treatment decreased the GABA releases from synaptosomes both in a Ca2+-free Ringer's solution and in a high K+ Ringer's solution. When the convulsions were protected by pretreatment with AOAA, the decreased GABA releases in both the conditions rose to or above the normal levels. Therefore, it is suggested that the decrease in GABA release from the nerve endings, because of the decrease of GABA content in the same compartment, is possibly an important factor in the onset of some kinds of convulsions.

Aminooxyacetic Acid↗
PubMed1978

Demonstration of a delay time during aggregation of diluted solutions of deoxyhemoglobin S and hemoglobin CHarlem in concentrated phosphate buffer.

Diluted solutions (less than 100 mg/dl) of deoxygenated sickle hemoglobin (Hb S) and Hb CHarlem were found to aggregate with a clear demonstration of a delay time when dissolved in concentrated phosphate buffer. The delay time could be shortened by increasing the concentration of either hemoglobin or phosphate. Upon cooling or bubbling with carbon monoxide, the aggregates melted quickly. The logarithmic plot of reciprocal delay time versus hemoglobin or phosphate concentration shows a linear line with a slope of 2.7 for hemoglobin and 44 for phosphate. This suggests that diluted solutions of Hb S aggregate by the nucleation mechanism which is similar to that reported in the gelation of concentrated Hb S solution.

Buffers↗
PubMed1978

Stabilizing effect of various organic solvents on protein.

The rate of denaturation of hemaglobin and other proteins by mechanical shaking is strongly affected by organic solvents. A group pf solvents,including alcohols and ketones, was found to stabilize proteins at low concentrations, although these same organic solvents denatured proteins at high concentrations. The stabilizing effect of alcohols increased with increasing chain lenghts. The second group of solvents, including toluene and chloroform, showed only a destabilizing effect, while the third group of solvents such as formamide and pentane had no effect over a wide range of concentrations. Organic solvents may be used to protect or denature a specific protein in solutions containing various proteins.

Alcohols↗
PubMed1978

Comparative studies of Hb Lepore Boston, Hb A2, and Hb A.

Several functional tests were performed to compare Hb A, Hb A2, and Hb Lepore Boston, which has a delta-beta crossover in the region of residues 87 to 116. Oxygen equilibrium curves determined by an automatic apparatus in 0.1 M potassium phosphate buffer, pH 7.0, at 20 degrees showed that the p50 was 5.8 mm Hg for Hb Lepore Boston, in contrast to 8.1 and 10.3 mm Hg for Hb A2 and Hb A, respectively. The n values (Hill coefficinets) of Hb Lepore Boston and Hb A2 were slightly smaller than that of Hb A. The effect of 2,3-diphosphoglycerate and inositolhexophosphate on the p50 of Hb Lepore Boston and Hb A2 was less than that on the p50 of Hb A. The molecular stability to mechanical shaking of Hb Lepore Boston and Hb A2 showed that the oxy forms of Hb Lepore Boston and Hb A2 denatured at a rate 3 times faster than that of Hb A. MetHb Lepore Boston was more unstable than MetHb A2 to mechanical shaking. These results indicate that, although the molecular stability of Hb Lepore Boston is more similar to that of Hb A2 than that of Hb A, the oxygen-binding properties of Hb Lepore differ from both Hb A and Hb A2.

Carboxyhemoglobin↗
PubMed1978

Sequence of oxygen binding by hemoglobin.

A nitroxide spin-label probe was attached directly to a propionic acid group of heme in either the alpha or the beta chain of hemoglobin. The electron paramagnetic resonance (EPR) spectrum of the spin label is altered by the spin-state change of the heme iron to which the spin label is attached. These hybrid hemoglobins showed normal optical and functional properties, indicating that the attachment of the spin label did not perturb the function of hemoglobin. Upon deoxygenation of alpha-heme-spin-labeled hemoglobin, EPR signals changed proportionally with oxygen saturation (determined by measuring absorption spectra). This result indicates that there is no binding preference between the alpha and beta chains of hemoglobin. However, the cross plot for the fraction of the EPR changes vs. the fraction of oxygen saturation deviated significantly from the diagonal straight line in response to the addition of 2,3-diphosphoglycerate and inositol hexaphosphate. The deviation indicated that the EPR change precedes the optical change at low oxygen tension. This result implies that, in the presence of organic phosphate, oxygen binds preferentially to the alpha subunit of deoxyhemoglobin. This conclusion was supported by the result obtained with beta-heme-spin-labeled hemoglobin: the direction of the deviation for beta-heme-spin-labeled hemoglobin in the presence of diphosphoglycerate and inositol hexaphosphate was opposite to that obtained for alpha-heme-spin-labeled hemoglobin. However, the curve deviated even in the absence of organic phosphate. This deviation for beta-heme-spin-labeled hemoglobin can be explained by the intersubunit interaction of hemoglobin. From these results, it was concluded that, in the absence of organic phosphate, oxygen combines with the alpha and beta chains with equal probability whereas, in the presence of organic phosphate, oxygen binds preferentially to the alpha chains of hemoglobin.

Adult↗
PubMed1978

A simple test for detection of sickle hemoglobin in the neonatal period.

The ease of denaturation by shaking of a solution of oxyhemoglobin S (oxy-Hb S) forms the basis for a simple and reliable test for confirmation or rapid detection of Hb S in children and adults. Comparison of results of this test with those from agar gel electrophoresis in capillary blood samples from 187 black neonates at 2 to 7 days of life showed no overlap of the amounts of hemoglobin precipitated between the group of neonates with Hb S (5.7--12.0%) and that without Hb S (0--4.7%). These results indicate that the shaking test, by virtue of being simple, reliable and inexpensive, may be used to detect and confirm Hb S in large numbers of neonates before their discharge from the nursery.

Anemia, Sickle Cell↗
PubMed1978

[Effect of cardiocrome on EEG arousal response (author's transl)].

The experiment was made on effect of Cardiocrome (containing Cytochrome c, Co-Carboxylase and Flavin mononucleotide), Cytochrome c and Cytidine diphosphate (CDP) choline on the EEG arousal response induced by electrical stimulation of mesencephalic reticular formation in 68 unanesthetized immobilized cats. The arousal response was accelerated by intravenous injection of Cardiocrome, Cytochrome c and CDP-choline. The accelerating effect of Cardiocrome was more prominet than that of Cytochrome c. In conclusion, it can be drawn that Cardiocrome has an arousal effect on consciousness.

Animals↗