Search PubMed⌕ Search

Biomedical subjects

T Asakura

Publications and source records attributed to T Asakura.

At least 415 records · Page 23Linked to original sources
PubMed1980

Aggregation of hemoglobin S and hemoglobin CHarlem with nonsickle hemoglobin in concentrated phosphate buffer.

The effect of HbA and HbF on both the aggregation and deaggregation of deoxy HbS and deoxy HbCHarlem in concentrated phosphate buffers was studied by a turbidimetric method. Although pure deoxy HbA is fully soluble in 2.4 M potassium phosphate buffer, the same concentration of deoxy HbAS was insoluble in the same buffer. Since there was little dissolved hemoglobin in the solute of a mixture of HbA and HbS, and since the intensity of turbidity was approximately twice that which would be expected from deoxy HbS alone, deoxy HbA must have coaggregated with deoxy HbS. Similar studies with mixtures of HbS and HbF showed different results. The rates of aggregation of deoxygenated mixtures of HbS and HbF were much slower than those of similar mixtures of HbS and HbA. Measurements of the absorption spectrum of the solute after centrifugation and the electrophoresis of both the aggregates and the solutes showed that a portion of the HbF was coaggregated with HbS, while some of the HbS was still in solution. The solubility of HbS and mixtures of sickle and nonsickle hemoglobins in 2.2 M phosphate buffer increased in the order of HbS, HbACHarlem, HbAS, HbCHarlem, HbSF, and HbFCHarlem.

Blood Protein Electrophoresis↗
PubMed1980

[A case of intracranial chordoma with a special reference to the findings in computed tomography (author's transl)].

A case of chordoma was reported with a special reference to the computed tomography. A 22-year-old female, who had been in good health, was admitted to Kagoshima University Hospital on December 8, 1978 with a chief complaint of diplopia. Physical examination was nothing particular and neurologic examination revealed the left abducent nerve palsy. The labolatory findings including blood count, serum electrolytes, hormonal study, carcinoembrynonic antigen (CEA) and alpha-fetoprotein were within normal limits. Plain skull filsm showed a retro-sellar calcification in combination with a bony erosion of the dorsum sellae and the clivus. The left vertebral arteriography and the left carotid arteriography showed a space taking lesion extended from the retro-clival to the left parasellar region. The axial CT scanning showed a round and irregular high density area consistent with calcification, at the retro-clival area, middle cranial fossa, and parasellar region in the left side, and no enhancement effect was acquired. The coronal CT appearance showed a round but discontinuous high density area like a coral reef, based on the clivus. These CT findings indicated the extension of the space taking legion, clearly. Intra-capsular removal of the tumor was performed and histologic examination confirmed the chordoma. It will be emphasized that CT scan, particularly coronal section was one of the most useful diagnostic procedure of amss of the skull base.

Adult↗
PubMed1979

Formation of nuclei during delay time prior to aggregation of deoxyhemoglobin S in concentrated phosphate buffer.

The delay time prior to aggregation of deoxyhemoglobin S was found to be shortened significantly if monomeric deoxyhemoglobin S was added near the end of the expected delay time. This suggests the formation of a preaggregation complex of deoxyhemoglobin S, probably so-called "nuclei", near the end of the delay time. In fact, the molecular weight of deoxyhemoglobin S as measured by a low angle laser light scattering photometer increased exponentially during the delay time prior to the visible aggregation of deoxyhemoglobin S. These results support the nucleation-controlled aggregation mechanism for the aggregation of deoxyhemoglobin S in concentrated phosphate buffer.

Biopolymers↗
PubMed1979

The solubility of sickle and non-sickle hemoglobins in concentrated phosphate buffer.

A new turbidimetric method for the direct measurement of the solubility of oxy- and deoxyhemoglobins (Hb) in concentrated phosphate buffer has been established. The principle of the method is the formation of a homogeneous emulsion when hemoglobin is introduced in concentrated phosphate buffer. The solubility of the oxy and deoxy forms of Hb A, Hb S, Hb C, Hb F, and Hb CHarlem (beta 6Glu leads to Val, beta 73Asp leads to Asn) has been studied. The solubility of deoxy-Hb S was the lowest and the solubility curve was broader than those of the other hemoglobins indicating that the aggregates of deoxy Hb S require more water to be dissolved. The solubility of oxy- and deoxyhemoglobins depends on temperature and pH. The solubility of hemoglobins is increased as the temperature is lowered and the pH is raised. The pH dependency of the solubility of deoxy-Hb S in high phosphate buffer was opposite to that of the minimum gelling concentration of deoxy-Hb S. The order of the solubility of Hb CHarlem, Hb FS, Hb AS, Hb CS, and Hb S in concentrated phosphate buffer corresponds to the order of minimum gelling concentration of these hemoglobins or hemoglobin mixtures. Solubility studies of a 1:1 mixture of deoxy-Hb A and deoxy-Hb S show that deoxy-Hb A aggregates in 2.42 M phosphate buffer in which pure deoxy-Hb A is totally soluble. This result indicates that deoxy-Hb S interacts with deoxy-Hb A and decreases its solubility.

Buffers↗
PubMed1979

Use of heme spin-labeling to probe heme environments of alpha and beta chains of hemoglobin.

A spin label attached to a propionic acid group of the heme has been used to probe the heme environment of the alpha and beta chains of hemoglobin in both the subunit and tetrameric forms. The electron paramagnetic resonance (EPR) studies of hemoglobin hybrids in which the spin label is attached to either the alpha- or beta-heme (alpha2SLbeta 2 or alpha2beta2SL) and spin-labeled isolated chains (alphaSL and betaSL) show that: 1) alpha- and beta-hemes have different environments in the tetrameric forms of oxy-, deoxy-, and methemoglobins as well as in isolated single chains; 2) when isolated subunits associate to form hemoglobin tetramers, the environment of the alpha-heme changes more drastically than that of the beta-heme; 3) upon deoxygenation of hemoglobin, the structure in the vicinity of the alpha-heme changes more drastically than that of the beta-heme; and 4) upon the addition of organic phosphates to methemoglobin, the change in the spin state of the heme irons mainly arises from beta-heme. The results demonstrate conclusively that the alpha and the beta subunits of hemoglobin are structurally nonequivalent as are their structural changes as the result of ligation. The relationship of EPR spectrum and structure of hemoglobin is discussed.

Electron Spin Resonance Spectroscopy↗
PubMed1979

Spin-label studies of membrane-associated denatured hemoglobin in normal and sickle cells.

A maleimide spin label (N-(1-oxyl-2,2,5,5-tetramethylpyrrolidinyl)-maleimide) was reacted with oxyhemoglobin-free cell stromata of normal and sickle cells. The EPR spectrum of spin-labeled red cell membranes showed that the spin labels are attached to at least two different binding sites. There was a major signal, A, which characterized a strongly immobilized environment and a minor signal, B, which characterized a weakly immobilized environment. Quantitative EPR measurements using equal amounts of Hb AA and Hb SS red blood cells demonstrated that Hb SS red cell membranes had an approximately four times higher EPR signal intensity than Hb AA red cell membranes ((7.98 +/- 1.14 . 10(5) and (2.2 +/- 1.2) . 10(5) spin labels/cell, respectively). Moreover, the ratio of signal intensities A and B are different in these cells. Comparative spectrophotometric studies of membrane-associated denatured hemoglobins of Hb AA and Hb SS red cell membranes suggested that the EPR signal A is derived from spin labels attached to membrane-associated denatured hemoglobin, while signal B is mainly from spin labels attached to membranes. The combination of EPR spectrum of Hb AA membranes pretreated with N-ethylmaleimide and that of spin-labeled precipitated hemoglobin further strengthened this conclusion.

Anemia, Sickle Cell↗
PubMed1979

Oxygen dissociation curves in children with anemia and malignant disease.

Two automatic apparatuses utilizing a dual wavelength spectrophotometer were used to perform oxygen dissociation curves on microsamples of blood. The method provides a complete print-out of an oxygen dissociation curve in 15--20 min and the P50 vlues obtained in normal individuals agree closely with those obtained by classical methods. These apparatuses were used to measure oxygen affinity, ie P50, in anemic children with malignant disease prior to treatment and in children undergoing therapy. Red cell 2,3-DPG levels were also measured. In patients with anemia at the time of diagnosis and prior to therapy, the P50 values and 2,3-DPG levels were elevated as is usual in other types of anemia. However, when oxygen affinity and 2,3-DPG levels were measured in anemic patients receiving treatment, three types of response to anemia were noted: 1) increased P50 and 2,3-DPG; 2) normal or low P50 and 2,3-DPG, and; 3) normal or low P50 with increased 2,3-DPG. Patients who adapted poorly to anemia during treatment had usually received prior intensive chemotherapy and transfusion therapy, and their pattern of red cell glycolytic intermediates was consistent with a red cell population with an increased cell age. The failure of some patients to respond to anemia with a decrease in oxygen affinity has implications in regards to the hemoglobin level at which they should be transfused.

Adult↗
PubMed1979

Blood flow velocity in pulmonary microvessels of bullfrog.

Flow velocity in the pulmonary microvessels of the exposed lung of bullfrogs was measured by means of a laser Doppler microscope of an oblique backward mode, together with a signal-analyzing system having a time sharing circuit triggered by the R-wave of the ECG. By these means, measurements of the changes of flow velocity contour in the cardiac cycle were made. Flow velocity was clearly pulsatile in response to cardiac cycles in all microvessels including capillaries. Flow velocities in the arteriole and venule consistently decreased for a short period after the R-wave (84 +/- 33 msec (mean +/- SD) in the arteriole and 130 +/- 31 msec in the venule, respectively) and rapidly increased up to a maximicronm value. The mean flow velocities in arterioles (diameter 50 +/- 17 micron) and venules (39 +/- 9 micronm) were 2.29 +/- 0.32 and 2.30 +/- 0.27 mm/sec. The amplitudes of pulsatile flow in these vessels were 0.83 +/- 0.31 and 0.63 +/- 0.16 mm/sec, respectively. In the capillary the times from the R-wave to the minimicronm and maximum values were variable. In some cases the velocity gradually increased without first decreasing and the increase sharply accelerated a certain time after the R-wave. The mean velocity in the pulmonary capillary and the amplitude of the pulsatile flow ere 1.78 +/- 0.31 and 0.37 +/- 0.12 mm/sec, resepctively. The ratios of the pulsatile amplitude to the mean velocity in the pulmonary capillary, venule and arteriole averaged 0.21, and 0.36, respectively.

Animals↗
PubMed1979

Automated method for determination of oxygen equilibrium curves of red cell suspensions under controlled buffer conditions and its clinical applications.

The accurate determination of the oxygen equilibrium curve (OEC) of whole blood or red cell suspensions requires special considerations to avoid the secondary effects due to lactate formation, removal of carbon dioxide, use of anticoagulants, etc. An automated apparatus has been constructed that can record the whole OEC of red cells within 20 min. The instrument also can be used to record the OEC of hemolysate. The pH, temperature, and PO2 are monitored constantly during the measurement. Using this instrument, the effects of pH, temperature, carbon dioxide, anticoagulants, and buffers on the OEC of normal fresh blood have been investigated. The OEC of normal blood, blood containing abnormal hemoglobin, or enzyme, were determined. The results were compared with those obtained using commercial OEC apparatuses.

Autoanalysis↗
PubMed1979

Hereditary stomatocytosis: association of low 2,3-diphosphoglycerate with increased cation pumping by the red cell.

The levels of glycolytic intermediates have been measured in red cells from patients with both overhydrated and dehydrated varieties of the hereditary stomatocytosis syndrome. Red cell 2,3-diphosphoglycerate was reduced by 33% below normal in all patients with either stomatocyte or target cell morphologies (i.e. over or under hydrated varieties respectively). The relative decrement in 2,3-diphosphoglycerate was even greater when abnormal cells were compared with control cells with similar reticulocytosis. Red cell ADP concentrations in stomatocytosis were significantly increased above normal but ATP concentrations were not significantly changed. Whole blood oxygen affinity in stomatocytosis was increased in proportion to the lowered content of diphosphoglycerate. Some new parameters of membrane transport in hereditary stomatocytosis have been measured. Platelet K+ and Na+ concentrations and platelet K+ permeability were normal in stomatocytosis. The number of 3H-uridine transport sites in stomatocytes were increased by 9-39% above normal and this increment was the same as the increment in red cell lipids (0-38%). Hereditary stomatocytes contain 2-10-fold more cation pumps than normal and the increased active cation pumping may explain the high ADP, the low 2,3-diphosphoglycerate concentration and the increased oxygen affinity in this syndrome.

Adenosine Diphosphate↗
PubMed1979

Small ventricles detected by CT-scanning in epileptic patients.

Relatively young 119 cases of generalized epilepsy and 99 controls of an identical age were selected. The bicaudate CVI was measured and the results were as follows: 1) In our cases, the mean of bicaudate CVI showed a smaller value than those of Hahn's in both epilepsy and control groups. 2) When the value of bicaudate CVI was set up below the point of 8.5 as "excessively small ventricle," the incidence rate of "excessively small ventricle" was 9% in the control group and 31% in the epilepsy group. The data showed higher incidences of small ventricles in the epilepsy group, and that the younger females have a tendency to have higher incidences of small ventricles. 3) To make clear the reason for the higher incidences of small ventricles in epilepsy, the small ventricle group and the non-small ventricle group in epilepsy were compared with each other from the points of the clinical course, EEG findings and frequency of attacks. No correlation or difference between them was found. Further investigation will be needed to make clear the etiology of small ventricles in epilepsy. However, it could be said at the present stage that not so many atrophic changes were observed in the younger patients of generalized epilepsy.

Adolescent↗