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T Arimitsu

Publications and source records attributed to T Arimitsu.

16 recordsLinked to original sources
PubMed2006

Effects of rate of decrease in power output in decrement-load exercise on oxygen uptake.

The purpose of this study was to examine how oxygen uptake (Vo2) in decrement-load exercise (DLE) is affected by changing rate of decrease in power output. DLE was performed at three different rates of decrease in power output (10, 20 and 30 watts.min(-1): DLE10, DLE20 and DLE30, respectively) from power output corresponding to 90 % of peak Vo2. Vo2 exponentially increased and then decreased, and the rate of its decrease was reduced at low power output. The values of Vo2 in the three DLE tests were not different for the first 2 min despite the difference in power output. The relationship between Vo2 and power output below 50 watts was obtained as a slope to estimate excessive Vo2 (ex-Vo2) above 50 watts. The slopes were 10.0+/-0.9 for DLE10, 9.9+/-0.7 for DLE20 and 10.2+/-1.0 ml.min(-1).watt(-1) for DLE30. The difference between Vo2 estimated from the slope and measured Vo2 was defined as ex-Vo2. The peak value of ex-Vo2 for DLE10 (189+/-116 ml.min(-1)) was significantly greater than those for DLE20 and for DLE30 (93+/-97 and 88+/-34 ml.min(-1)). The difference between Vo2 in DLE and that in incremental-load exercise (ILE) below 50 watts (DeltaVo2) was greater in DLE30 and smallest in DLE10. There were significant differences in DeltaVo2 among the three DLE tests. The values of DeltaVo2 at 30 watts were 283+/-152 for DLE10, 413+/-136 for DLE20 and 483+/-187 ml.min(-1) for DLE30. Thus, a faster rate of decrease in power output resulted in no change of Vo2 at the onset of DLE, smaller ex-Vo2 and greater DeltaVo2. These results suggest that Vo2 is disposed in parallel in each motor unit released from power output or recruited in DLE.

Adult↗
PubMed2006

Comparison of oxygen uptake at the onset of decrement-load and constant-load exercise.

The purpose of the present study was to examine whether the level of oxygen uptake (V(.)(O2) at the onset of decrement-load exercise (DLE) is lower than that at the onset of constant-load exercise (CLE), since power output, which is the target of V(.)(O2) response, is decreased in DLE. CLE and DLE were performed under the conditions of moderate and heavy exercise intensities. Before and after these main exercises, previous exercise and post exercise were performed at 20 watts. DEL was started at the same power output as that for CLE and power output was decreased at a rate of 15 watts per min. V(.)(O2) in moderate CLE increased at a fast rate and showed a steady state, while V(.)(O2) in moderate DLE increased and decreased linearly. V(.)(O2) at the increasing phase in DLE was at the same level as that in moderate CLE. V(.)(O2) immediately after moderate DLE was higher than that in the previous exercise by 98+/-77.5 ml/min. V(.)(O2) in heavy CLE increased rapidly at first and then slowly increased, while V(.)(O2) in heavy DLE increased rapidly, showing a temporal convexity change, and decreased linearly. V(.)(O2) at the increasing phase of heavy DLE was the same level as that in heavy CLE. V(.)(O2) immediately after heavy DLE was significantly higher than that in the previous exercise by 156+/-131.8 ml/min. Thus, despite the different modes of exercise, V(.)(O2) at the increasing phase in DLE was at the same level as that in CLE due to the effect of the oxygen debt expressed by the higher level of V(.)(O2) at the end of DLE than that in the previous exercise.

Adult↗
PubMed2006

Relationship between oxygenation in inactive biceps brachii muscle and hyperventilation during leg cycling.

Inactive forearm muscle oxygenation has been reported to begin decreasing from the respiratory compensation point (RCP) during ramp leg cycling. From the RCP, hyperventilation occurs with a decrease in arterial CO2 pressure (PaCO2). The aim of this study was to determine which of these two factors, hyperventilation or decrease in PaCO2, is related to a decrease in inactive biceps brachii muscle oxygenation during leg cycling. Each subject (n = 7) performed a 6-min two-step leg cycling. The exercise intensity in the first step (3 min) was halfway between the ventilatory threshold and RCP (170+/-21 watts), while that in the second step (3 min) was halfway between the RCP and peak oxygen uptake (240+/-28 watts). The amount of hyperventilation and PaCO2 were calculated from gas parameters. The average cross correlation function in seven subjects between inactive muscle oxygenation and amount of hyperventilation showed a negative peak at the time shift of zero (r = -0.72, p<0.001), while that between inactive muscle oxygenation and calculated PaCO2 showed no peak near the time shift of zero. Thus, we concluded that decrease in oxygenation in inactive arm muscle is closely coupled with increase in the amount of hyperventilation.

Adult↗
PubMed1988

[A case of eclampsia with intraventricular hemorrhage].

Our case is a 31-year-old primipara who had undergone a cesarean section for multiple pregnancy and was referred to our clinic because of attack of eclampsia. On admission, her consciousness level was lethargic. Computed tomography on admission showed high density area indicating right paraventricular hemorrhage with ventricular perforation, and low density areas in bilateral basal ganglia. Examination of the cerebral angiogram done six days after onset of symptoms revealed multisegmental vasospasm in Willis' circle mainly. An emergent ventricular drainage was performed. Two weeks later, repeat angiogram revealed that spasm had almost disappeared. Repeat CT scan three months after the onset showed small low density area in the right caudate nucleus and disappearance of the low density areas in bilateral basal ganglia. Her clinical course was uneventful and she was discharged without neurological deficit at about three weeks after the onset. In spite of absence of subarachnoid clot on CT scan, remarkable multisegmental spasm was found on cerebral angiogram. We suspected that eclampsia may have been responsible for the spasm in this case. Bleeding was believed to have originated in the superolateral angle of the lateral ventricle. It was supposed that infarcted hemorrhage or bleeding from small artery due to changes in arterial or venous pressure might have occurred and penetrated into the lateral ventricle.

Adult↗
PubMed1984

[Sustained-release pellet of vasodilators--basic experiment].

We examined the efficacy of slow-release, and prolonged diffusion silicone pellets mixed with papaverine hydrochloride in the treatment of cerebral vasospasms following subarachnoid hemorrhage. In addition the diffusion of the other vasodilating agents (diltiazem and nicardipine) into the saline solution using the same silicone materials was also investigated. Papaverine hydrochloride was either packed in silicone tubes (packed type) or polymerized with silicone elastomer, Silastic MDX-4-4210 (solid type). The solid type pellet is cylindrical-(diameter 3 mm, length 30 mm) and contains 40 w/v% of pure powder of papaverine. The amount of the delivered drug was measured for 5 weeks at 37 degrees C and at room temperature. The diffusion rate of the solid type pellet was about 5 times higher than that of the packed one. The diffusion rates of both types of pellets were about 10 times higher at 37 degrees C than at room temperature. The cummulative amount of the delivered drug from the solid type pellet was 37.1% of the initial packed volume at 37 degrees C in the first 3 weeks. The diffusion of diltiazem and nicardipine which were polymerized 30 w/v% in silicone elastomer was observed for 3 weeks at 37 degrees C only in solid type pellet form. The diffusion rate was measured under the condition of either continuous shaking or standing. The results showed the same diffusion rates for diltiazem and nicardipine, with no difference in diffusion rate between the "shaking" and "standing" groups. The diffusion rate showed inverse exponential curves, and was 5-20 X 10(-5)/day/mm2 of initial volume until 5 days.(ABSTRACT TRUNCATED AT 250 WORDS)

Delayed-Action Preparations↗
PubMed1980

[Effect of various kinds of glucocorticoids on experimental brain edema (author's transl)].

Although the effectiveness of glucocorticoids for the treatment of cerebral edema has been widely accepted in neurosurgical practice, but its mechanism is still obscure. Also the dose equivalent of various kinds of glucocorticoid preparation is still uncertain. Only the dose equivalent determined by the test examining an antiinflammatory effect on a growth of glanulation, has been applied for the treatment of brain edema. The authors attempted to establish the dose equivalent of each kinds of glucocorticoid for the treatment of cerebral edema. Cold induced cerebral edema was produced by touching a metal probe at the temperature of -90 degrees C for 3 minutes on the right parietal cortex of rat brain. Hydrocortisone (16 mg/kg), prednisolone (3.2 mg/kg), methylprednisolone (3.2 mg/kg), dexamethasone (0.8 mg/kg) and betamethasone (0.8 mg/kg) were administered at the time of 3 hours prior or after the cold injury. The animals were sacrificed 24 hours after injury and the grade of brain edema was determined by the changes of water content in the brain tissue. For this purpose, the authors developed a new method of measuring water content in the brain tissue using tritiated water and a liquid scintillation counter. In the group of animals which were treated with prednisolone, dexamethasone or betamethasone, the water content was significantly decreased compared to the value of non-treated animals. But in the animals treated with hydrocortisone or methylprednisolone, no significant changes of the water content was observed. But in the animals treated with double doses of hydrocortisone (32 mg/kg) or methylprednisolone (6.4 mg/kg), cerebral edema was improved significantly. From these results the authors concluded that the dose equivalent of each kinds of glucocorticoid for the treatment of the brain edema was as follows: hydrocortisone: prednisolone: methylprednisolone: dexamethasone: betamethasone = 40 : 4 : 8 : 1 : 1.

Animals↗
PubMed1979

Computed tomography profiles of periventricular hypodensity in hydrocephalus and leukoencephalopathy.

Profiles of hypodense periventricular white matter, drawn from the interior of the frontal horns through the surrounding white matter to the peripheral gray matter, were analyzed in 65 patients. Abnormal curves were grouped into four patterns: linear, double-slope, plateau, and bimodal. The first two, found primarily in hydrocephalic patients, appear to be due to transependymal passage of cerebrospinal fluid (CSF). The linear pattern was found more frequently in acute cases and indicates breakdown of the ventricular wall as a barrier. The double-slope pattern probably indicates a persistent or restored barrier effect at the wall, with residual CSF infiltration of the parenchyma. Most of the other patients' curves showed either a plateau pattern or (especially in primary leukoencephalopathy) a bimodal ("bumpy") pattern which is believed to correspond to the nonuniform nature of the pathological process.

Cerebral Ventriculography↗
PubMed1978

Periventricular leukomalacia related to neonatal anoxia: recognition by computed tomography.

Periventricular areas of decreased attenuation coefficient were demonstrated by computed tomography (CT) in two infants with neurological involvement after episodes of neonatal hypoxia. This CT finding is related to anoxic periventricular leukomalacia, which is well documented in the literature. Follow-up CT scans in our two patients demonstrated reversibility of the white matter changes.

Brain Diseases↗
PubMed1977

White-gray matter differentiation in computed tomography.

A numerical analysis has been performed on six regions of interest within the brain for a total of 60 patients. Three areas of white matter and three of gray matter were included. A difference of 7.1 +/- 1.3 Hounsfeld units (HU: 1,000 scale) was found between white and gray matter. For eight patients who were under 15 years of age, the difference was 5.1 +/- 0.6 HU. Contrast injection resulted in a general increase of values, with gray matter showing a greater elevation by 0.5 HU. The numerical evaluation of white and gray matter has proven to be useful in the diagnosis of leukoencephalopathy.

Adolescent↗
PubMed1977

[Evaluation of the role of brain scintigraphy in pineal tumors (author's transl)].

From January, 1969 to December, 1975, 1700 patients underwent sequential brain scintigraphy with Tc-99-m-pertechnetate. All the scintigrams were obtained on a scintillation camera with high-resolution collimator in our clinic. Intracranial tumors were confirmed in 449 cases and 21 cases out of those were pineal tumors which were diagnosed by clinical symptoms, air study, angiography and Conray-or Myodil-ventriculography. In these pineal tumors, 14 (67%) out of the 21 cases had positive scan on scintigrams. All of our cases of teratoma (one case) and teratocarcinoma (two cases) showed clear abnormal uptake, though it had been reported that they do not tend to have positive results on scintigrams. We also performed scintigraphy on 11 cases out of the 21, both before and after 60Co radiation therapy. In the cases which showed either same grade or more increased abnormal uptake on scintigrams after radiation therapy, compared with that before radiation therapy, compared with that before radiation, their prognoses were poor. On the other hand, those cases which showed decreased abnormal uptake after radiation, have had a healthy daily activities. From these experiences, it may be concluded that brain scintigraphy is clinically valuable not only for making the diagnosis, but for evaluating the effect of radiation therapy and the prognosis in the cases of pineal tumor.

Adolescent↗