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Biomedical subjects

T Asakura

Publications and source records attributed to T Asakura.

At least 325 records · Page 18Linked to original sources
PubMed1986

[A case of multiple cerebellar hemangioblastomas with congenital deafness, juvenile diabetes mellitus and retinal angioma].

It has already been noted that hemangioblastoma is occasionally complicated with various diseases, especially retinal angioma, cysts of kidney and/or pancreas, vascular disorders, and furthermore about 10% of hemangioblastoma are multiple. The authors report here a case of multiple cerebellar hemangioblastomas accompanied with congenital deafness, juvenile diabetes mellitus and retinal angioma. The patient, a 38-year-old man who complained of disturbance of consciousness, headache and vomiting, admitted to our hospital on October 6, 1982. He was born in consanguineous marriage family and his elder sister was also suffered from congenital deafness and juvenile diabetes mellitus, but no angiomas. CT and angiography showed a left side cystic and a right side small cerebellar lesions with remarkable ventricular enlargement. Ventriculo-peritoneal shunt and suboccipital craniectomy & removal of the tumors were performed on October 6, and November 8, 1982 succeedingly. From a point of view of hereditary occurrence, the authors investigated these complicated lesions recognized in this patient. It revealed that this case did not belong to any other categories of hereditary syndromes which were already reported and so authors considered that this was an extremely rare condition. Moreover, in case of multiple hemangiomas, cerebral angiography could be a more useful method than CT scan to detect multiplicity of the lesions in the posterior fossa.

Adult↗
PubMed1986

[Application of renal subcapsular assay to rat malignant brain tumor].

As a rapid screening method for testing chemotherapeutic agents against human tumor explants, renal subcapsular assay has been established by Bogden et al (1978). The authors investigated the effectiveness of the technique of Bogden for rat glioma. Preselected 1 mm3 fragments of viable tumor tissue of rat (CDF) were implanted under the renal capsule of normal immunocompetent rats. Then initial and final tumor sizes (formula; see text) were measured in situ with an oculometer inserted into a surgical microscope, and evaluated the changes of tumor sizes. The experiments were divided into three groups. The first group was that tumor pieces of rat (CDF) were implanted under the renal capsule of the syngenetic rats (CDF). Non-irradiated and preirradiated (400 rad) heterogenetic rats (Wistar) were used as the second and third groups. The explanted tumor pieces grew rapidly in the first group (syngenetic rats). On the other hand, poor growth of the second group (non-irradiated heterogenetic rats) was seen within 7 days after implantation, and rejected completely until 15 days after implantation. Explanted tumor pieces in the third group (pre-irradiated heterogenetic rats), however, grew enough big, though the change of tumor sizes was less than that of the first group. Histological examination was also performed. In the first and third group, proliferation of glioma cells was remarkable under the renal capsule, and neovascularization in the explanted tumor tissue was provided from the capsule, first, and then parenchym of the kidney. Even necrosis and hemorrhage were seen in the tumor tissue 15 days after implantation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

[A case of clival chordoma without bone destruction].

A case of clival chordoma without bone destruction is reported. A 28-year-old man was admitted to Kagoshima University Hospital on April 8, 1983 with the complaints of headache, displopia and gait disturbance. Neurological examination revealed the right eighth, ninth, tenth nerve palsy and gait disturbance. Plain skull firms showed no abnormality and left vertebral arteriography revealed a displacement of basilar artery to the left side. The CT scanning showed a low density area at the retroclival region, and enhancement was acquired slightly. Metrizamide cisternography, CT cisternography showed retroclival round tumor and no destruction of the bone. The tumor which invaded intradurally was removed totally. Histological examination confilmed the chordoma. In this report, it will be stressed that when clival chordoma invades intradually, subtemporal approach will be most favorable, and metrizamide CT cisternography is one of the useful diagnostic procedures of retroclival mass.

Adult↗
PubMed1986

[A study on the direct antitumoral effect of interferon-alpha on human glioma].

The direct antitumoral effect of interferon-alpha on human glioma was suggested in a study involving tissue culture, and scanning and transmission electron microscopy. Consequently, intratumoral local administration of interferon-alpha for four cases of human glioma was performed, and each survival period from the initiation of its application was seven, eight, three and two months. Slight direct antitumoral effect of interferon was observed in the findings of both CT scan and autopsy in our series, but the survival time was not as great as we had expected. One of the reasons for this was thought to be insufficient permeability of interferon-alpha into the residual infiltrating tumor tissue. Therefore, the use of systemic administration of interferon or another adjuvant therapy with local administration of interferon would be expected to produce better results.

Adult↗
PubMed1986

[Studies on somatomedin C in diabetic pregnancies].

Somatomedins have been shown to have potent mitogenic activities in cultured cells and also promote individual growth. We studied the concentrations of somatomedin C in diabetic pregnant women and rats. Serum and liver somatomedin C were measured by RIA double antibody method, after extraction with an ODS silica column. Serum somatomedin C concentrations were 20.45 +/- 5.14 nM/l (mean +/- S.D.) in nonpregnant normal women. In nonpregnant diabetic women, these were 16.96 +/- 4.37 nM/l, which were significantly lower than those of normal nonpregnant women. The concentrations of pregnant normal and diabetic women were similar to those of nonpregnant normal women. Maternal concentrations of somatomedin C significantly correlated with infant weight (r = 0.41, p less than 0.05, n = 41). Serum somatomedin C concentrations in the normal infants were 6.45 +/- 1.97 nM/l, which were considerably lower than those of their mothers. In the infants from diabetic mothers, these were 9.17 +/- 3.28 nM/l, which were significantly higher than those of normal infants. Rat serum somatomedin C concentrations which were 15.86 +/- 2.37 nM/l in nonpregnant normal rats, tended to increase during pregnancy. The mother's concentration significantly correlated with fetus weight (r = 0.491). Liver somatomedin C levels decreased in diabetic and pregnant states. Fetal rats had lower hepatic somatomedin C, which was about 10% of the mother's levels. These were higher in the fetuses from diabetic mothers. These finding suggested that the mother's somatomedins might contribute to fetal growth.

Animals↗
PubMed1985

Stability of asymmetrical hybrid hemoglobins. Determination by anaerobic high performance liquid chromatography.

Asymmetrical hybrid hemoglobins formed in mixtures of Hb A and Hb S, Hb F and Hb S, Hb S and Hb York(beta 146 His----Pro), and Hb A and Hb York were separated by high performance liquid chromatography on cation and anion exchange columns under anaerobic conditions. The ratio of the hybrid hemoglobin to the total mixture was consistently lower than that theoretically expected and decreased with longer elution times. The hybrid tetramer appears to be unstable even under anaerobic conditions and dissociates into alpha beta dimers. The time course of dissociation of the hybrid hemoglobins was determined by varying the separation programs and thus separating the hybrid hemoglobin at different elution times. The rate of the dissociation of the hybrid hemoglobins studied follows first order kinetics. The lines representing the time course of dissociation of hybrid hemoglobins were extrapolated to time 0 to determine the fraction of the hybrid hemoglobin in the mixture prior to separation. The values obtained for equimolar mixtures of Hb A and Hb S and Hb York and Hb S or Hb A were in agreement with the expected theoretical value (50%). In contrast, the value obtained for hybrid hemoglobin FS was slightly less (about 40%). AY and SY hybrid hemoglobins dissociated into dimers at a considerably faster rate than did AS and FS hybrid hemoglobins, possibly because of the mutation at the beta 146-position in hybrid hemoglobins containing alpha beta Y dimers. This mutation hinders the formation of salt bridges that normally stabilize the "T" quaternary conformation. Since such hybrid hemoglobins have a partial "R" conformation even when deoxygenated, their rate of dissociation to dimers is expected to increase.

Anaerobiosis↗
PubMed1985

Effect of cetiedil on platelet aggregation and thromboxane synthesis.

Cetiedil was found to inhibit platelet aggregation and thromboxane synthesis induced by thrombin and arachidonic acid. When platelets were activated by thrombin, half maximal inhibition (ED50 effective dose of cetiedil necessary for 50% inhibition) for platelet aggregation was 100 microM while that for thromboxane B2 (TXB2) production was 50 microM. When arachidonic acid was used, the ED50 for platelet aggregation was 100 microM while that for TXB2 production was 150 microM. The presence of calcium ions did not affect on the inhibitory effects of cetiedil. The cAMP level in platelets did not increase after incubation with cetiedil. Cetiedil appears to inhibit the activation of platelets related to thromboxane synthesis.

Antisickling Agents↗
PubMed1985

Giant mucocele of paranasal sinuses.

A large mucocele of the frontal and ethmoidal sinuses with extracranial, intracranial, and intraorbital extension accompanied by total destruction of the left frontal sinus was treated successfully. We chose a two-stage surgical procedure for radical removal of the lesion. It is important to ascertain the degree of dural involvement, not only because extensive involvement of the dura mater presents technical surgical difficulties, but also because this knowledge provides clues regarding the pathology of the lesion. Even after surgical treatment, the mucocele may recur if the patent sinus ostium is exposed to the dura mater, or if the ostium subsequently becomes blocked.

Dura Mater↗
PubMed1985

Angiographically occult arteriovenous malformations.

Angiographically occult arteriovenous malformations not associated with clinically recognizable intracranial hemorrhage appear to be rare. We are reporting three cases of histologically proven arteriovenous malformations of the brain that were angiographically occult. These cases presented with seizures or attacks of dizziness, and were detected by computed tomography scan, radionuclide scan, or both. The preoperative diagnosis was granuloma in the first case and meningioma in the other two. After surgical exploration, biopsy revealed an arteriovenous malformation in each case. A review of 47 cases in the literature is tabulated and etiologies of the angiographically occult arteriovenous malformations are discussed. The routine use of computed tomography scan and timely, appropriate surgical intervention with the operating microscope for the removal of these deeply situated lesions is necessary for the diagnosis and therapy.

Adult↗
PubMed1985

Shape change of sickled erythrocytes induced by pulsed rf electrical fields.

The shape change of sickled erythrocytes induced by electrical pulses was investigated under various experimental conditions using different suspending media. The purpose of this research is to find a set of conditions under which sickled erythrocytes from an individual with sickle cell anemia (SS erythrocytes) can be desickled with minimal damage to the membrane. Previously we observed, using 0.9% NaCl solution, that rounding of the SS erythrocytes eventually led to hemolysis even when the field was turned off. Using short pulses, we have now observed that the rounding of sickled erythrocytes does not necessarily lead to hemolysis if buffer solutions such as Hanks' solution are used. The cause of the shape change is believed to be the perforation of the erythrocyte membrane by the potential induced by applied fields. The field-induced membrane potential has been calculated for spherical cells and infinitely long cylinders. Using an ellipsoid of revolution as a model, we generalize the calculation of membrane potential. These calculations indicate that a transverse field is less effective in inducing a potential than a longitudinal field.

Anemia, Sickle Cell↗
PubMed1985

Effect of cetiedil on the superoxide-generating system of porcine neutrophils.

Cetiedil, alpha-cyclohexyl-3-thiopheneacetic acid 2-(hexahydro-1H-azepin-1-yl)-ethyl ester, was found to inhibit the generation of superoxide (O2-) by porcine neutrophils exposed to various stimulators. The concentration of cetiedil required for 50% inhibition was about 45 microM when neutrophils were stimulated by phorbol myristate acetate. Cetiedil not only decreased the rate of generation of O2-, but prolonged the lag time prior to the production of O2-. The inhibitory effect of cetiedil on the O2(-)-generating activity of the NADPH oxidase in the membrane vesicles was less than that on whole cells; the concentration of cetiedil necessary for 50% inhibition was about 250 microM. To study the mechanism of cetiedil's effect on the membrane, the transmembrane potential of neutrophils and the intracellular free Ca2+ concentration were monitored by using fluorescence probes, diS-C3-(5), and quin-2, respectively. Cetiedil caused depolarization of the membrane potential and increased the intracellular free Ca2+. These results indicate that integrity of ionic distribution is necessary to activate the O2(-)-generating system of neutrophils.

Animals↗
PubMed1985

Effects of cetiedil on the oxidative metabolism of activated polymorphonuclear leucocytes.

Cetiedil, alpha-cyclohexyl-3-thiopheneacetic acid 2-(hexahydro-lH-azepin-l-yl)-ethyl ester, was found to specifically suppress oxygen uptake by polymorphonuclear leucocytes (PMN) that were exposed to myristate or heat-killed E. coli. The chemical had no effect on the basal respiration rate of PMN in the resting state. Inhibition of oxygen uptake by cetiedil was proportionate to the degree of inhibition of the generation of O-2 and H2O2. It was also found that cetiedil suppressed the rate of the phagocytosis by PMN of opsonized oil droplets. Cetiedil had no effect on subcellular NADPH oxidase, an enzyme responsible for the respiratory burst that is activated by the perturbation of PMN plasma membrane with phagocytable particles or stimulators such as myristate. These results suggest that cetiedil affects the trigger mechanism of the plasma membrane to inhibit the activation of NADPH oxidase.

Animals↗
PubMed1985

An applicability study on a CT-guided stereotactic technique for functional neurosurgery.

When a CT-guided stereotactic technique for functional neurosurgery is adopted, extremely precise targeting is needed to obtain satisfactory surgical results. In this study the authors have investigated the accuracy of the target points determined by CT-guided techniques and compared with those of conventional roentgenographically controlled stereotactic procedures. Stereotactic surgery, employing the Brown-Roberts-Wells (BRW) system, was performed contemporarily 26 times in 23 patients, that is, 9 times in 8 patients for functional neurosurgery using with the roentgenographic method, and 17 times in 15 patients with the CT-guided method only for intracranial neoplasm biopsy. As a result, there were no problems of accuracy of determining the target points by CT-guided stereotactic surgery with the BRW system. When applying this technique for functional neurosurgery, it should be pointed out that there could be a discrepancy within 2 mm from the conventional target determination.

Brain Diseases↗
PubMed1985

Oxygen binding and stability properties of Hb Santa Ana (beta 88 Leu----Pro).

Hb Santa Ana (beta 88 Leu----Pro) was found at a level of 30% of total hemoglobin in red cells from a patient with congenital hemolytic anemia. Since no detailed functional studies of this hemoglobin have been done previously, we determined oxygen equilibrium curves of red cell suspensions, hemolysates, and isolated Hb Santa Ana. The P50 values obtained were 22.5 mm Hg (37 degrees C, pH 7.4) for red cell suspensions (normal mean = 27.0 mm Hg), 10.0 mm Hg (25 degrees C, pH 7.0) for hemolysate (normal = 13.5 mm Hg), and 1.3 mm Hg (25 degrees C, pH 7.0) for isolated Hb Santa Ana. Measurements of mechanical stability of Hb Santa Ana showed that the oxy-form of this hemoglobin was 10 times more unstable than that of Hb S and 100 times more unstable than that of Hb A. The deoxy-form of Hb Santa Ana was as unstable as its oxy-form, indicating that no stabilization (R----T conversion) takes place upon the deoxygenation of Hb Santa Ana.

Anemia, Hemolytic, Congenital↗