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Biomedical subjects

T Asakura

Publications and source records attributed to T Asakura.

At least 289 records · Page 16Linked to original sources
PubMed1988

The effect of deoxygenation rate on the formation of irreversibly sickled cells.

The effects of the deoxygenation rate on the formation of irreversibly sickled cells (ISCs) were investigated by using metabolically replete sickle cells (SS cells). We found that the formation of ISCs required Ca2+ and that the amount formed depended on the rate of deoxygenation. When less dense SS discocytes were deoxygenated slowly by flushing with 95% N2 and 5% CO2 at a rate of 3 mL/min, the percentage of ISCs increased from 5% to 26.5% after 24 hours. In contrast, upon rapid deoxygenation (10, 35 mL/min) ISC formation was reduced significantly. The difference may be related to fact that more sickle-shaped cells were formed upon slow deoxygenation than upon the rapid deoxygenation that resulted in the formation of star-shaped and granulated cells. So-called ISCs were formed more easily from sickle-shaped cells. To express the shape of sickled cells numerically, we calculated the mean maximum cell length (MCL) after cells were incubated under various deoxygenation conditions. The MCL of slowly deoxygenated SS cells after 24 hours of incubation was about twice (20.0 +/- 7.0 micron) that of quickly deoxygenated (35 mL/min) SS cells (12.5 +/- 5.0 microns) (initial MCL, 8.0 +/- 1.0 micron). The decrease in potassium content was greater with slow deoxygenation than with rapid deoxygenation. Because the increase in sodium influx was less than that of potassium efflux under slow deoxygenation, SS cells became more dense than those rapidly deoxygenated. In the absence of Ca2+, morphological changes were the same as in the presence of Ca2+; however, under this condition there was no change in density, and no ISCs were formed regardless of the rate of deoxygenation. These results demonstrate that the number of ISCs formed correlates with the MCL. The length of fibers of sickle hemoglobin may be a determinant of the length of sickled cells. This suggests that membrane stretching plays an important role in cell density and irreversible membrane deformation.

Anemia, Sickle Cell↗
PubMed1988

[A case of sparganosis mansoni cerebri as an epileptogenic lesion].

The authors report a case of sparganosis mansoni cerebri. This 33-year-old man had experienced adversive seizures. Plain CT demonstrated a high density area with surrounding low density area, and homogeneously enhanced with contrast medium in the frontoparietal region. 99TcO4 brain scintigram showed an abnormal hot area. On operating as a cerebral tumor, we had removed a living Sparganum mansoni from the cerebral granuloma. This is the third report in the world to our knowledge of literature, in which alive intracranial Sparaganum mansoni was removed. Sparganosis mansoni cerebri is very rare, and therefore it is very difficult to diagnose exactly before operation. However we should remember this disease considering the life history of the patient with convulsion.

Adult↗
PubMed1988

[A case of cerebellar arteriovenous malformation with hemifacial spasm at onset].

A case of cerebellar AVM onset with hemifacial spasm was reported. The patient, a 47 year old woman, had been suffering from lt. hemifacial spasm for 10 years, and she visited our hospital for operation. Preoperative angiography revealed that there was an AVM in the lt. cerebellar hemisphere fed by the lt. SCA and the lt. PICA. In addition, a non-ruptured saccular aneurysm was observed on the feeding SCA. The microvascular decompression was performed and the AVM was removed, since the lt. facial nerve had been compressed by this elongated and redundant PICA. After the operation, lt. hemifacial spasm disappeared. Two months after the operation, the aneurysm disappeared angiographically. These findings indicated that the hemodynamic stress due to the presence of AVM seemed to have resulted in ectasia or redundancy of the PICA and in the development of the aneurysm. Such a case was quite rare and it may be the first time to be reported in literatures.

Cerebellum↗
PubMed1987

Effect of amino acid at the beta 6 position on surface hydrophobicity, stability, solubility, and the kinetics of polymerization of hemoglobin. Comparisons among Hb A (Glu beta 6), Hb C (Lys beta 6), Hb Machida (Gln beta 6), and Hb S (Val beta 6).

Surface hydrophobicity, stability, solubility, and kinetics of polymerization were studied using hemoglobins with four different amino acids at the beta 6 position: Hb A (Glu beta 6), Hb C (Lys beta 6), Hb Machida (Gln beta 6), and Hb S (Val beta 6). The surface hydrophobicity increased in the order of Hb C, Hb A, Hb Machida, and Hb S, coinciding with the hydrophobicity of the amino acid at the beta 6 position. Solubility of the oxy-form of these hemoglobins decreased in relation to increases in their surface hydrophobicity, suggesting that the solubility is controlled by the strength of hydrophobicity of the amino acid at the beta 6 position. The solubility of the oxy-form of these hemoglobins is always higher than that of the deoxy-form. There is a similar linear relationship between the solubility and surface hydrophobicity among deoxyhemoglobins A, C, and Machida. However, the solubility of deoxy-Hb S deviated significantly from the expected value, indicating that the extremely low solubility of deoxy-Hb S is not directly related to the hydrophobicity of the beta 6 valine. Kinetic studies on the polymerization of deoxy-Hb Machida revealed a distinct delay time prior to polymerization. This confirms our previous hypothesis that beta 6 valine is not responsible for the delay time prior to gelation. The kinetics of the polymerization of 1:1 mixtures of sickle and non-sickle hemoglobins were similar to those of pure Hb S, suggesting that only one of the two beta 6 valines is involved in an intermolecular contact. In mixtures of equal amounts of Hb S and Hb A, Hb C, or Hb Machida, half of the asymmetrical AS, SC, and S-Machida hybrid hemoglobins behaved like Hb S during nucleation, while the other half behaved like the non-sickle hemoglobin.

Drug Stability↗
PubMed1987

Effect of the beta 73 amino acid on the hydrophobicity, solubility, and the kinetics of polymerization of deoxyhemoglobin S.

The role of Asp-beta 73 on the surface hydrophobicity and solubility of hemoglobin was studied using Hb A, Hb S, Hb C Harlem (alpha 2 beta 2Val-6,Asn-73), and Hb Korle Bu (alpha 2 beta 2Asn-73). The surface hydrophobicity of the oxy form of these hemoglobins increased in the order of Hb A, Hb Korle Bu, Hb S, and Hb C Harlem, coinciding with the change in solubility. The same is not true for deoxyhemoglobins. The solubilities of deoxy-Hb S and deoxy-Hb C Harlem were much lower than that expected from their surface hydrophobicity. Although the hydrophobicity of deoxy-Hb C Harlem is greater than that of deoxy-Hb S, the solubility of deoxy-Hb S is only one-third that of deoxy-Hb C Harlem. This deviation must be caused by the substitution of Asn for Asp at the beta 73 position and its inhibitory effect on hydrogen bonding in Hb S polymers. The kinetics of the polymerization of 1:1 mixtures of the deoxy form of S-C Harlem, A-C Harlem, Korle Bu-S, and Korle Bu-C Harlem were studied in comparison with that of deoxy-Hb S and deoxy-Hb C Harlem alone. All of these binary mixtures polymerized with a distinct delay time prior to polymerization. Based on the results of kinetic studies, the probability factors for nucleation of S-C Harlem, A-S, A-C Harlem, S-Korle Bu, and Korle Bu-C Harlem hybrid hemoglobins were calculated as 0.65, 0.5, 0.5, 0.15, and 0.17, respectively, in comparison with that of Hb S (1.0). The probability factor for Hb C Harlem alone was 0.3. These data suggest that the Asp-beta 73 is directly involved in nucleation during Hb S polymerization and that the beta 73 is always trans to the active Val-beta 6 in the formation of nuclei.

Aspartic Acid↗
PubMed1987

Adsorbed behavior of spin-labeled silane coupling agent on colloidal silica studied by electron spin resonance.

The adsorption mechanism of silane coupling agent on the colloidal silica surface is studied with spin-labeled silane coupling agent using ESR method. The density of the adsorbed silane molecules was determined to be approximately 1.5-2 molecules per 100 A2 of the silica surface in 95% ethanol solution. In addition, ESR signal of spin-labeled agent adsorbed on the colloidal silica surface was composed of two components; slow component attributable to the agents adsorbed directly on the Si--OH groups of the silica surface through hydrogen bond formation and rapid one attributable to the agents interacted with such adsorbed silane molecules.

Acrylic Resins↗
PubMed1987

Changes in proton T1 in dog brains due to the administration of haloperidol.

Changes in proton T1 in dog brains due to the administration of haloperidol were determined by the intravenous administration of a single dose of 20 mg of haloperidol to mongrel dogs. The MRI used was the Aberdeen type with the static magnetic field of 0.1 T. A coil made exclusively for these animals (bore diameter 120 mm) was used. There was a significant increase in the T1 value in the striate body 30 minutes and more (within two hours) after the administration of haloperidol. Subtraction images were also obtained by subtracting the image of the pre-treatment (control) T1 values from the image of the post-treatment values (2 hours after the injection). The subtraction images also revealed increases in the T1 values of the striate body.

Animals↗
PubMed1987

Langer-Giedion syndrome with del 8 (q24.13-q24.22).

An 8-year-old boy with the features of Langer-Giedion syndrome except for short stature is described. Chromosome analysis using high resolution G-banding techniques revealed an interstitial deletion of the long arm of chromosome 8:46,XY,del(8)(q24.13-q24.22).

Child↗
PubMed1987

Transport and metabolism of pyridoxine and pyridoxal in mice.

[3H]Pyridoxine or [3H]pyridoxal in physiological amounts was orally administered to mice and the distribution of isotope between the six recognized forms of vitamin B6 and pyridoxic acid was determined at different times after the administration in the intestine, liver, blood, and brain. After 7 min about 50% of the radioactivity in pyridoxine and pyridoxal had been absorbed by the intestine and transported to the blood and other organs. When [3H]pyridoxine was administered, labeled pyridoxal, pyridoxal- and pyridoxine-phosphate were found in the intestine and liver, and labeled pyridoxine could not be detected in the peripheral blood but substantial amounts of labeled pyridoxal and pyridoxal-phosphate were found in the blood. The time course of the blood [3H]pyridoxal levels following the administration of [3H]pyridoxine was similar to that following the administration of [3H]pyridoxal. These results suggest that the intestine and/or liver play a major role in converting dietary pyridoxine to circulating pyridoxal which is taken up and phosphorylated by other organs. Moreover, most of the blood [3H]pyridoxal was shown to be located in the plasma. This localization may facilitate utilization by the organs.

Animals↗