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Biomedical subjects

T Asakura

Publications and source records attributed to T Asakura.

At least 163 records · Page 9Linked to original sources
PubMed1994

31P-magnetic resonance spectroscopic study on the effect of glycerol on cold-induced brain edema.

The aim of the present study was to determine the effects of a hyperosmotic agent, 10% glycerol, on both brain energy metabolism and intracellular pH (pHi) in experimental vasogenic brain edema. Vasogenic brain edema was induced by cold injury applied to bilateral parietal portions in 13 mongrel dogs (7 glycerol, 6 control) while, 3 dogs were used as control. Before and at 24 hours after the injury, sequential phosphorous-31 magnetic resonance spectroscopy (31P-MRS) was performed for 2 hours in order to determine phosphocreatine (PCr), beta-adenosine triphosphate (beta-ATP), inorganic phosphate (Pi) levels and pHi. At 24 hours following cold injury, both PCr/Pi and ATP/Pi ratios significantly decreased from 7.75 to 3.97 and from 2.26 to 1.25, respectively. Furthermore, a moderate decrease in pHi of 7.16 to 7.01 was significantly demonstrated during the same experimental period. Administration of glycerol for 30 minutes significantly increased PCr/Pi from 3.97 to 5.06 and ATP/Pi from 1.25 to 1.72, respectively. Also, glycerol administration caused a significant increase in pHi from 7.01 to 7.11. This study indicates that cryogenic injury, in which formation and expansion of vasogenic brain edema a known to occur, results in disturbed brain energy metabolism and in intracellular acidosis; moreover, the administration of glycerol can ameliorate either or both of these derangements.

Acid-Base Equilibrium↗
PubMed1994

Pyridoxal kinase immunoreactivity in rabbit brain.

Murine polyclonal antibody against purified bovine brain pyridoxal kinase (EC 2.7.1.35) was generated and showed cross-reactivity with rabbit brain pyridoxal kinase. This antibody was used to immunohistochemically examine the distribution of pyridoxal kinase in the rabbit brain. The cytoplasm of neuronal cells and neuroglial cells in the cerebral cortex, hippocampal region, brain nuclei and cerebellar cortex showed positive staining with various degrees of intensity. The neuronal cells and surrounding fibers in some brain nuclei, such as the area tegmentalis ventralis or the substantia nigra, showed intense staining. The neuronal cells of the hippocampal region showed somewhat weak reactivity, but some with intense reactivity were found sparsely distributed and positive staining fiber networks of a very low density were also observed.

Animals↗
PubMed1994

Metabolic adaptation of skeletal muscles to gravitational unloading.

Responses of high-energy phosphates and metabolic properties to hindlimb suspension were studied in adult rats. The relative content of phosphocreatine (PCr) in the calf muscles was significantly higher in rats suspended for 10 days than in age-matched cage controls. The Pi/PCr ratio, where Pi is inorganic phosphate, in suspended muscles was less than controls. The absolute weights of soleus and medial gastrocnemius (MG) were approximately 40% less than controls. Although the % fiber distribution in MG was unchanged, the % slow fibers decreased and the % fibers which were classified as both slow and fast was increased in soleus. The activities (per unit weight or protein) of succinate dehydrogenase and lactate dehydrogenase in soleus were unchanged but those of cytochrome oxidase, beta-hydroxyacyl CoA dehydrogenase, and citrate synthase were decreased following unloading. None of these enzyme activities in MG changed. However, the total levels of all enzymes in whole muscles decreased by suspension. It is suggested that shift of slow muscle toward fast type by unloading is associated with a decrease in mitochondrial biogenesis. Further, gravitational unloading affected the levels of muscle proteins differently even in the same mitochondrial enzymes.

Animals↗
PubMed1994

The mechanism of chlorpromazine-induced red blood cell swelling.

1. Chlorpromazine (CPZ)-induced red blood cell (RBC) swelling was investigated by determination of electrolyte, mean cell volume (MCV) and water content changes in CPZ-treated cells. 2. CPZ-induced RBC swelling is dose-, hematocrit- and pH-dependent, and is associated with a net increase in RBC monovalent cation and Cl- contents. 3. The partition coefficient (Kp) for the CPZ-RBC membrane interaction is pH dependent (Kp = 2500 at pH 7.8; Kp = 840 at pH 6.8). 4. Despite the pH dependence of Kp values an equal number of CPZ molecules is required to induce a 12% increase in MCV at pH 7.8 and 6.8.

Adult↗
PubMed1994

Structural analysis of highly oriented poly(p-phenylene-terephthalamide) by 15N solid-state nuclear magnetic resonance.

The structure of an aromatic polyamide, poly(p-phenylene-terephthalamide) (PPTA), was studied in the solid state using 15N nuclear magnetic resonance (NMR) spectroscopy. Spectra of uniaxially aligned molecules placed with the axis of alignment both parallel with and perpendicular to the applied magnetic field were analyzed to yield the orientations of specific molecular bonds with respect to the fiber axis. The 15N chemical shift tensor was characterized by simulating powder pattern spectra of both PPTA and a model compound, benzanilide. Chemical shift and dipolar coupled chemical shift line shapes were calculated through Euler angle transformations from the principal axis system (PAS) reference frame to the fiber axis system (FAS) frame. The orientations of NH and NC' bonds in PPTA are determined as well as the orientational distribution of the PPTA fiber axis. The structural parameters determined for PPTA are compared with those obtained by X-ray diffraction.

Magnetic Resonance Spectroscopy↗
PubMed1994

Synthesis of 12(R)- and 12(S)-hydroxyeicosatetraenoic acid by porcine ocular tissues.

Microsomal fractions from porcine ocular tissues synthesized 12(S)-5,8,10,14-hydroxyeicosatetraenoic acid [12(S)-HETE] from arachidonic acid by a membrane-bound lipoxygenase and 12(R)-HETE by the cytochrome P450-dependent monooxygenase system. Both activities were the highest in corneal microsomes. The 12(R)-HETE synthesizing activity of corneal microsomes was dependent on NADPH and inhibited by 0.1 mM SKF-525A, an inhibitor of P450 enzymes. The activity to form 12(R)-enantiomer was significantly enhanced by treatment of corneal epithelium with 3-methylcholanthrene or clofibrate. The induced activity was suppressed by cycloheximide, indicating that the induction of enzyme activities involved a translational process. The effect of these inducers on 12(R)-HETE synthesizing activity appeared to be additive. The activity to form 12(S)-enantiomer was markedly stimulated by 3 mM CaCl2. The 12-lipoxygenase of corneal microsomes was capable of oxygenating linoleic acid in addition to arachidonic acid, a characteristic of 12-lipoxygenases of the leukocyte type. 12(R)-HETE at 10(-6) M inhibited almost completely the Na,K-ATPase of corneal epithelium but had little or no effect on ciliary epithelial enzymic activity. 12(S)-HETE at 10(-6) M also inhibited corneal enzymic activity but to a lesser extent, and had no significant effect on ciliary epithelial Na,K-ATPase activity.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1994

Cutaneous arterial fibromuscular dysplasia: a case report and electron-microscopic study.

A case of a 39-year-old female with fibromuscular dysplasia (FMD) manifesting subcutaneous pulsatile nodules on the right side of her forehead and on her right wrist is reported here. These nodules proved to be FMD aneurysms of the frontal ramus of the right superficial temporal artery and the right radial artery. The patient had also suffered a stroke with subarachnoidal bleeding as a result of this disease. Angiographic examination showed aneurysms in the union and the bilateral vertebral arteries, a branch of the right renal artery, and one the right lumbar artery. A biopsy specimen taken from the frontal branch of the right superficial artery revealed segmental intimal thickening consistent with intimal fibroplasia type FMD upon histological examination. Electron-microscopic findings were also discussed in connection with the histogenesis of the disease. This appears to be the second case of FMD involving arteries in the skin to be reported in the dermatological literature.

Adult↗
PubMed1994

Opposing effects of indomethacin and nordihydroguaiaretic acid on macrophage function and tumor growth.

The effects of indomethacin (INDO) and nordihydroguaiaretic acid (NDGA) were compared on macrophage function and tumor growth. Intraperitoneal injections (5 mg/kg/day, 6, 8 or 9 days) of INDO in C57BL/6 mice stimulated the cytotoxicity of peritoneal macrophages and inhibited growth of subcutaneous B16 melanoma, whereas NDGA injections suppressed macrophage cytotoxicity, increased macrophage prostaglandin-E2 (PGE2) release, and enhanced the tumor growth. Further, pretreatment of macrophages in vitro with the INDO group serum increased cytostasis against B16 tumor cells, while the use of NDGA group serum reduced it. Incubation of tumor-bearer's macrophages in vitro with INDO (10(-6) M and 10(-7) M) or 10(-6) M NDGA for 4 h reduced PGE2 release, but 10(-7) M NDGA markedly enhanced the PGE2 release. Our data indicate that INDO and NDGA are able to modulate the macrophage function directly, and produce opposing effects on macrophage function and tumor growth. Inhibitory actions of INDO and NDGA on the cyclooxygenase or lipoxygenase pathway of arachidonic acid metabolism appear to contribute to their effects.

Animals↗
PubMed1994

Responses of beta-adrenoceptor in rat soleus to phosphorus compound levels and/or unloading.

Responses of beta-adrenoceptor (beta-AR) in rat soleus to gravitational unloading and/or changes in the levels of phosphorus compounds by feeding either creatine or its analogue beta-guanidinopropionic acid (beta-GPA) were studied. A decrease in the density of beta-AR (about -35%) was induced by 10 days of hindlimb suspension, but the affinity of the receptor was unaffected. Suspension unloading tended to increase the levels of adenosine triphosphate and phosphocreatine and decrease inorganic phosphate. Even without unloading, the beta-AR density decreased after an oral creatine supplementation (about -20%), which also tended to elevate the high-energy phosphate levels in muscle. However, an elevation of beta-AR density was induced (about +36%) after chronic depletion of high-energy phosphates by feeding beta-GPA (about +125%). Data suggest that the density of beta-AR in muscle is elevated if the high-energy phosphate contents are chronically decreased and vice versa. However, it may not be directly related to the degree of muscle contractile activity.

Animals↗
PubMed1994

Identification of the cerebral motor cortex by focal magnetic stimulation: clinical application to neurosurgical patients.

A figure-8 coil was designed that was capable of generating currents over a relatively limited area. In this study, we used the figure-8 coil to localize human cerebral motor cortex by transcranial magnetic stimulation and assessed its value as a diagnostic tool for neurosurgical disease. The subjects were 10 normal volunteers and 12 neurosurgical patients. The points obtaining a response were plotted and the response area was delineated for each stimulus output. Rectangular coordinates were subsequently determined for the C3-Cz-C4 line with the stimulation sites set 1.0 cm apart. Then amplitude and latency maps were displayed by a computer wave map program. In normal volunteers, the posterior margin of the site where a threshold +5% stimulus obtained a response from the THE or ADM muscles almost coincided with the central sulcus. The optimal areas were relatively narrow on the amplitude and latency maps. In the patient with a left frontal convexity meningioma, the left threshold +5% area for the THE and ADM muscles showed marked anterolateral shift. No threshold map could be obtained on the affected side in patients with metastatic tumor and astrocytoma. Low perfusion areas caused by moyamoya disease and arteriovenous malformations produced narrowing of the optimal zone on the threshold map of the affected side. Hyperexcitability of the motor cortex was recognized in the arteriovenous malformation patients. Transcranial focal magnetic stimulation is a useful noninvasive diagnostic method for identification of the human cerebral motor cortex. It provides important information about changes in the localization and excitability of the motor cortex in neurosurgical patients and should be helpful for treatment planning.

Adult↗
PubMed1994

Responses of contractile properties in rat soleus to high-energy phosphates and/or unloading.

Responses of contractile properties of soleus to unloading and/or changes in high-energy phosphate contents were studied in rats. Reduction of high-energy phosphates, especially phosphocreatine, in ankle extensors was induced by feeding beta-guanidinopropionic acid (beta-GPA). The major finding in the study was that the fatigability and speed-related contractile properties responded to unloading and creatine supplementation in a similar manner. The high-energy phosphate contents tended to be elevated after 10-d supplementation of creatine and hindlimb suspension. The shift toward slow-type, mainly due to an increased one-half relaxation time, was seen in rats fed beta-GPA. Such a shift was reversed by feeding creatine or by hindlimb suspension; however, the suspension-induced shift of contractile properties toward fast-type was not prevented completely by beta-GPA feeding. Although the muscle fatigue resistance did not change by beta-GPA feeding alone, the decrease in fatigue resistance following suspension and creatine supply was less in the beta-GPA group. It is suggested that the levels of high-energy phosphates and tension production play important roles in the regulation of contractile properties of the soleus muscle.

Animals↗
PubMed1994

Extra-axial ependymoma--case report.

A 13-year-old boy presented with a very unusual ependymoma extending extra-axially. Computed tomography demonstrated a tumor with a cyst and calcification adjacent to the dura and extending over the right occipital and parietal lobes. The cyst wall and solid tumor were enhanced postcontrast. Magnetic resonance imaging revealed that the solid tumor was isointense on T1-weighted images and a mixed iso- and high-intensity on T2-weighted images. The solid tumor and tissue surrounding the cyst were enhanced markedly by gadolinium-diethylenetriaminepentaacetic acid. Sagittal and coronal images demonstrated a multilocular tumor shadow. Cerebral angiography demonstrated a tumor fed by a posterior branch of the right middle meningeal artery but no feeders from the internal carotid and vertebral arteries. The tumor was removed en bloc. The histological diagnosis was clear cell-type ependymoma.

Adolescent↗
PubMed1994

Work stress and depressive symptoms among Japanese information systems managers.

The aim of the present study is to investigate the task-specific work stressors of IS (Information Systems) managers and to analyze the effect of these work stressors on depressive symptoms among these managers. A questionnaire including 33 items on work stressor was designed. Three hundreds of samples were gathered. The response-rate was 66.4%. Factor analysis suggested that these 33 items were categorized into 8 factors; job-overload, project-management, mental-rewards, job-latitude, communication with users, career development, technical difficulty, and work-environment. Eight work stressor scores were constructed using this Factor analysis. Using the 8 stressor-scores, and 6 items of background data, multiple regression analysis was conducted on the depressive symptoms score. Depressive symptoms were assessed using the Center for Epidemiologic Studies-Depression (CES-D) scale. The results showed that the factors of project-management, mental-rewards, and job-overload had significant effect on depressive symptoms (p < 0.01). It is indicated for the first time that software project management affects depressive symptoms in systems managers.

Depression↗
PubMed1994

Hydrocephalus due to villous hypertrophy of the choroid plexus in the lateral ventricles. Case report.

A case is reported of hydrocephalus due to overproduction of cerebrospinal fluid (CSF) caused by villous hypertrophy of the choroid plexus in the lateral ventricles. A 7-year-old girl with mental retardation developed gait disturbance; hydrocephalus and a Dandy-Walker cyst were detected on computerized tomography. She was initially treated with a ventriculoperitoneal shunt; however, shunting failed to control the hydrocephalus. The excessive outflow of CSF suggested choroid plexus abnormality, and magnetic resonance (MR) imaging revealed enlargement of the choroid plexus in both lateral ventricles. The patient was therefore diagnosed as having hydrocephalus induced by overproduction of CSF, which was controlled by resection of the choroid plexus. Histological examination showed the structure typical of normal choroid plexus. This is a rare case of villous hypertrophy of the choroid plexus in which MR imaging assisted in the diagnosis.

Brain Diseases↗
PubMed1994

[Clinical experiences of granulocyte colony stimulating factor for granulocytopenia after AC bypass].

We have successfully treated 3 cases of granulocytopenia, using Granulocyte Colony Stimulating Factor (G-CSF) after AC bypass surgery. All cases were male, aged 68, 75 & 54 years old, and underwent AC bypass surgery without transfusion except in case 1. Granulocyte cell counts decreased to 135/mm3 on 39th post-operative days (POD) in case 1, 624/mm3 on 13 rd POD in case 2, and 514/mm3 on 20th POD in case 3. In case 1, 300 micrograms of G-CSF was given intravenously for 3 days. In case 2, 100 micrograms of G-CSF for 1 day and 50 micrograms for 3 days was given subcutaneously, and in case 3, 100 micrograms of G-CSF was also given subcutaneously for 2 days. And their granulocyte cell counts all increased within few days. G-CSF is effective for patients with granulocytopenia after AC bypass surgery, but we need more experiences to know the best way of administration.

Aged↗
PubMed1994

[Outcome evaluation in putaminal hemorrhage by multiple regression analysis].

The aim of this study was to determine the factors that influence the prognosis of hypertensive putaminal hemorrhage. We investigated the outcome of the activity of daily living (ADL 1: full recovery at social life, 2: self cared, 3: required partial care at home, 4: remained bedridden, 5: vegetative state, 6: dead) one year after the onset of putaminal hemorrhage in comparison with initial data obtained on the day when it occurred. The following parameters were assessed: sex, age, side of hematoma, classification of computed tomography (CT) findings, neurological grade, degree of muscle power, hematoma volume, treatment, past history of cerebrovascular disease, and laboratory data. In 67 patients with putaminal hemorrhage, the relationships among these parameters were examined using Spearman's rank correlation analysis. Additionally, in 55 patients (24 male and 31 female) with complete data from the day of onset, multiple regression analysis was performed. The data of muscle power were handled by the quantification method. The result of Spearman's rank correlation coefficient indicated that the outcome had a positive correlation with age (correlation coefficient = 0.375), CT classification (0.595), neurological grade (0.714), hematoma volume (0.689), a past history of cerebrovascular disease (0.475), the white blood cell count (0.541), and the lactate dehydrogenase level (0.347). The outcome had a negative correlation with muscle power (-0.579) and the cholinesterase (-0.340).(ABSTRACT TRUNCATED AT 250 WORDS)

Activities of Daily Living↗
PubMed1994

[Changes in cerebral extracellular pH, cerebral blood flow and intracranial pressure induced by hypercarbic ventilation--assessment as a potential in vivo model of cerebral acidosis].

The effects of acidosis on ischemic brain damage are unclear and probably diverse. To establish an in vivo model of acidosis, the authors assess changes in extracellular brain pH (pHe), CBF and ICP induced by hypercarbic ventilation, and discuss the reliability and short comings of this experimental model. Acidosis was induced by increasing the inspired CO2 concentration in mechanically ventilated rats. pHe was measured with a pH-sensitive electrode implanted into the cortical mantle. The rats were divided into five groups according to the CO2 concentrations inspired: G-1, 0% control; G-2, -5-% CO2; G-3, -10-% CO2; G-4, -20-% CO2; G-5, -25-% CO2. Cortical blood flow was measured using a laser Doppler flowmeter, and ICP was also determined in each of the experimental groups. pHe decreased rapidly after the CO2 supply was turned on and remained almost constant at fixed concentrations of inspired CO2. pHe values diminished as the concentration of inspired CO2 decreased, as follows: G-2, -0.10 +/- 0.03; G-3, -0.31 +/- 0.08; G-4, -0.49 +/- 0.09; G-5, -0.64 +/- 0.10. The changes in pHe almost perfectly paralleled the changes in blood pH. The percentage increase in CBF was more than 200% in the G-2 groups and minimal increases in CBF, probably due to changes in blood pressure, were observed in from G-2 to G-5. Changes in CBF paralleled changes in systemic blood pressure, especially after the CO2 supply was turned off. ICP also rose after increasing the CO2 supply, and the pattern of changes was similar to that of CBF.(ABSTRACT TRUNCATED AT 250 WORDS)

Acidosis, Respiratory↗