Search PubMed⌕ Search

Biomedical subjects

T Asakura

Publications and source records attributed to T Asakura.

At least 271 records · Page 15Linked to original sources
PubMed1990

[A case of ectopic large pituitary adenoma].

Ectopic pituitary adenomas are very rare and only 17 cases have been reported. In this paper we present a case of large pituitary adenoma originating in the suprasellar region. A 26-year-old man was admitted to our clinic with a chief complaint of headaches. Neurological examination revealed slight disorientation and bilateral choked disk. Hormonal study revealed that the serum prolactin level was 3300ng/ml and serum growth hormone level was 29.5ng/ml. Computed tomography showed a large mass in the suprasellar region extending upward to the third ventricle and backward to the pons. T1-weighted MR imaging revealed that the intensity of the mass was the same as that of the cerebral cortex and the pituitary gland was showing high intensity in the pituitary fossa. The tumor was radically removed via the transpetrosal transtentorial approach. Histologically, the tumor was a prolactin-growth hormones producing pituitary adenoma. The literature was reviewed and the origin of the tumor was discussed.

Adenoma, Chromophobe↗
PubMed1989

Synthesis of functional human hemoglobin in transgenic mice.

Human alpha- and beta-globin genes were separately fused downstream of two erythroid-specific deoxyribonuclease (DNase) I super-hypersensitive sites that are normally located 50 kilobases upstream of the human beta-globin gene. These two constructs were coinjected into fertilized mouse eggs, and expression was analyzed in transgenic animals that developed. Mice that had intact copies of the transgenes expressed high levels of correctly initiated human alpha- and beta-globin messenger RNA specifically in erythroid tissue. An authentic human hemoglobin was formed in adult erythrocytes that when purified had an oxygen equilibrium curve identical to the curve of native human hemoglobin A (Hb A). Thus, functional human hemoglobin can be synthesized in transgenic mice. This provides a foundation for production of mouse models of human hemoglobinopathies such as sickle cell disease.

Animals↗
PubMed1989

Hemolysis by aliphatic alcohols and saponin measured by the coil planet centrifugation method.

Using the coil planet centrifugation method, the mechanism of hemolysis by alcohols and saponin was investigated. With this technique, erythrocytes are introduced into a gradient of hemolytic agents in saline, which is prepared in a long coiled polyethylene tube. The tube is centrifuged so that the cells move from a low to a high concentration of hemolytic agent. When the cells lyse, they release hemoglobin which remains stationary, and therefore hemolytic potency can be determined spectrophotometrically by the distance the cells move before lysing. We found that alcohols caused hemolysis at a particular concentration, whereas saponin-induced hemolysis was dependent on the amount of saponin accumulated in the environment of the cell. In addition, alcohols with longer carbon chains were more potent hemolytic agents than those with shorter chains, but each additional carbon group produced less of an increase in hemolysis per mole of alcohol. This chain-length dependency is consistent with a previous study on in vivo alcohol-induced hemolysis. The coil planet centrifugation method is also adaptable to comparative studies on the mechanism of other types of hemolysis, such as immune or drug-induced lysis, and to toxicological studies.

Alcohols↗
PubMed1989

Effect of retained components of excised tumor upon coexisting tumor.

Effects of locally treated and retained tumor tissue on the growth of a tumor at another site were investigated using Lewis rats bearing syngeneic fibrosarcoma. When an established tumor had completely regressed upon repeated intratumoral injections of L-phenylalanine mustard (PhM), the growth of secondarily transplanted tumor cells was inhibited. However, early excision of the PhM-injected tumor prevented the development of this effect. To study this effect directly, we excised one of the two established tumors in each thigh, and reinoculated into the excision wound either freeze-lysed 1 X 10(8) tumor cells (TC) or lysate chemically modified with PhM (PTC). We found that TC inoculation into the excision wound in 7 rats inhibited the growth of the remaining tumor and extended survival time (mean +/- SE, 27 +/- 1 days). With inoculation of PTC into the excision wound, the remaining tumor regressed and survival was significantly prolonged (32 +/- 2 days). In contrast, 7 untreated rats, each bearing two tumors, had a mean survival time of 22 +/- 0.1 days. Excision of one tumor (6 rats) did not affect the growth of the remaining tumor or survival time (23 +/- 1 days). We employed PhM to modify the immunogenicity of TC. However, if PhM dissociates from PTC, its cytotoxic effect may directly inhibit growth of the distant tumor. To examine this possibility, we divided 30 rats who had excision of one tumor, into three groups of 10 10.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

A correlative study between hippocampal atrophy quantified by tomo-pneumoencephalography and epileptogenic focus in temporal lobe epilepsy.

It appeared certain that we can quantify the rate of hippocampal atrophy by utilizing the sagittal cuts in tomo-pneumoencephalography. This is a reliable method to infer the side of the epileptogenic focus in temporal lobe epilepsy since a close correlation was disclosed between the side with more atrophic features of the hippocampus and that of the epileptogenic focus explored by depth EEG, in particular, in the mesial temporal focus group. On the other hand, it seems to be plausible that the hippocampal atrophy could be secondarily induced by epileptic discharges in the lateral temporal group. Namely, controversies dealing with the casual relationship of hippocampal atrophy should be discussed based on the epileptogenic focus localization in temporal lobe epilepsy.

Amygdala↗
PubMed1989

Distribution of activity converting 4-aminobutyraldehyde to gamma-aminobutyric acid in subcellular fractions of mouse brain.

The subcellular distribution of activity of 4-aminobutyraldehyde dehydrogenase (ABAL-DH) was studied in mouse brain. ABAL-DH was localized mainly in the crude mitochondrial fraction; most of the activity in this fraction was found in the subfraction containing synaptosomes, and the remainder was in the mitochondrial fraction. After osmotic disruption of synaptosomes, most of the activity was located in the synaptic cytosol, and the remainder was in the synaptic mitochondria. Sucrose density subfractionation of synaptosomes revealed that gamma-aminobutyric acid, glutamic acid decarboxylase, and ABAL-DH localized in a denser region of gradient fraction than the region containing acetylcholinesterase and choline acetyltransferase.

Acetylcholinesterase↗
PubMed1989

[Frequency spectra of EMG activities and mastication muscular development].

The purpose of this study was to investigate the change of frequency components of EMG (electromyograph) signals obtained from masticatory muscles in term of the development from deciduous mixed and permanent dentition using FFT (Fast Fourie Transform) algolism. A total of one hundred and fourty subjects who had no oral dysfunction were subjected. The subjects were divided into four groups: deciduous dentition (designated as G1), early mixed dentition (designated as G2), late mixed dentition (as G3) and permanent dentition (as G4). EMG signals were taken from the right masseter and temporal muscles using bipolar surface electrodes during tooth tapping, clenching in the intercupsal position and maximum biting and EMG were recorded on magnetic tape (FM data recorder). Three parameters on the surface EMGs were chosen for the measuring points such as 1) frequency range, 2) frequency of maximum peak (peak frequency), 3) strength of maximum peak (peak magnitude). The results obtained in the present studies were summarized as follows; 1) In the frequency range, temporalis showed a higher range than masseter muscle among every group and it decreased with the dentitional development. 2) As to the peak frequency and peak magnitude, the clenching has higher frequency than tooth tapping and maximum biting, and the those differences between each group were clarified with the development. 3) Cross-powerspectrum showed that the main frequency harmonized into high frequency at every movement, while the strength of the harmony maintained a high frequency and increased with the development of the muscles. As aforementioned, EMG spectra may also reflect on to muscle activities associated with dentitional development.

Dentition, Mixed↗
PubMed1989

[Report of surgical treatment of ASD in the aged].

5 surgical cases of atrial septal defect of the secundum type, aged 43, 45, 54, 58 and 67 respectively, are reported. Two of them were initially in functional class III, one in class II and two in class I. CTR were increased in all cases. Three of them had severe heart failure, especially in a 67 years-old patient severe respiratory obstructive disfunction was observed (FEV1.0:0.561). All of the cases had large pulmonary to systemic flow ratio (QP/QS greater than 3.0) and one had pressure-gradient of 20 mmHg between RV and PA. After the surgery CTR decreased, pulmonary arterial pressure also fell to normal value, and all cases symptomatically improved. It is concluded that surgery is life saving and appears to offer sustained clinical benefit to the older age group with advanced symptomatic disability, even if pulmonary hypertension or congestive heart failure are associated.

Adult↗
PubMed1989

[A new surgical approach to tricuspid annuloplasty: an extra-cardiac suture technique "AV-gathering"].

An extra-cardiac approach of annuloplasty for tricuspid insufficiency was carried out on cadavers. This procedure could effectively result in diminution of tricuspid valve ring circumference while not causing any decrease in right coronary blood flow. This approach could not only produce experimental tricuspid stenosis but also have a potential application in clinical functional tricuspid insufficiency. The procedure as well as the clinical implication were discussed.

Adult↗
PubMed1988

Effects of differences in charge and hydrophobicity of surface amino acids of hemoglobins on high-performance gel-permeation chromatography.

We studied the elution properties of the carboxy and deoxy forms of hemoglobins A, S, and C in gel-permeation high-performance liquid chromatography using TSK-GEL-SW-type columns. Since these hemoglobins have the same molecular mass but different amino acids at the beta 6 position, they are ideal for studies of the effect of charge and hydrophobicity on elution patterns in high-performance gel-permeation chromatography. Although there was a linear relationship between elution volume and logarithm of molecular mass of various proteins, the elution volumes of carboxyhemoglobins were found to be slightly greater than the expected volumes calculated from the molecular mass. The elution volumes of hemoglobins increased in the order of hemoglobins F, A, C, and S in 0.1 M phosphate buffer, pH 7.4, at room temperature. The elution volume of these hemoglobins was also dependent on pH and salt concentration. These results indicate that elution of these hemoglobins was affected by the electrostatic and hydrophobic interactions between hemoglobin molecules and polar sites of silica gel (with silanol groups) of the resin matrix of TSK-G2000-SW. This study may serve as a useful reference for separation and determination of molecular masses of proteins in the native state using gel-permeation liquid chromatography.

Amino Acids↗
PubMed1988

Facilitation of Hb S polymerization by the substitution of Glu for Gln at beta 121.

In an effort to clarify the role of Glu-beta 121 of Hb S molecules in polymerization, we studied the solubility and kinetics of polymerization of various mixtures of deoxyhemoglobins S (Glu-beta 6----Val) and D Los Angeles (Glu-beta 121----Gln). It is known that patients with Hb S-D Los Angeles have a relatively severe clinical course. Mixtures of Hb S and Hb D Los Angeles polymerized after a distinct delay time, the length of which depended on the initial hemoglobin concentration and the fraction of Hb S in the mixture. There was a linear relationship between the logarithmic plot of delay time and initial hemoglobin concentration. The line for a 1:1 mixture of Hb S and Hb D Los Angeles shifted to the right of that for deoxy-Hb S by 0.08. This shift is much smaller than the shift of 0.32 for 1:1 AS mixtures. From these data, the probability factor for nucleation of S-D Los Angeles hybrid hemoglobin was calculated to be 1.16, which is higher than that of Hb S (1.0) and AS hybrid hemoglobin (0.5). The degree of co-polymerization of Hb D Los Angeles in S-D Los Angeles mixtures was similar to that of Hb A in AS mixtures. The critical concentration for the polymerization of Hb D Los Angeles was between that of Hb A and Hb Machida, which has the same amino acid substitution (Glu----Gln) at the beta 6 position. These results suggest that the protein interaction of Hb S molecules during nucleation involves at least two steps. First, the Val-beta 6 of a Hb S molecule interacts hydrophobically with the Phe-beta 85 and the Leu-beta 88 of an adjacent Hb S molecule. In the second step, Glu-beta 121 weakens the interaction with His-beta 116 and Pro-alpha 114. The substitution of Glu-beta 121----Gln may strengthen this second reaction and facilitate nucleation as well as polymerization.

Glutamates↗
PubMed1988

Transport and metabolism of pyridoxine in the intestine of the mouse.

The absorption of pyridoxine from the intestine of the mouse was studied in whole animals. [3H]Pyridoxine was orally administered and the distribution of isotope between the six recognized forms of vitamin B6 was determined in portal and peripheral blood after the administration. When small doses (1.4 or 14 nmol) were administered, labeled pyridoxine could hardly be found in the portal blood as well as in the peripheral blood, although labeled pyridoxal and pyridoxal phosphate were found both in the portal and peripheral blood. However, when a large amount (46 or 140 nmol) was given, a significant amount of labeled pyridoxine was found with labeled pyridoxal and pyridoxal phosphate both in the portal and peripheral blood. These results suggest that a physiological dose of pyridoxine is transformed to pyridoxal in the intestinal tissues and then is released in the form of pyridoxal into the portal blood.

Animals↗