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T Shiga

Publications and source records attributed to T Shiga.

276 records · Page 16Linked to original sources
PubMedDate not supplied

Exercise-induced cerebral deoxygenation among untrained trekkers at moderate altitudes.

The pathophysiology of altitude-related disorders in untrained trekkers has not been clarified. In the present study, the effects of workload on cardiovascular parameters and regional cerebral oxygenation were studied in untrained trekkers at altitudes of 2700 m and 3700 m above sea level. We studied 6 males and 4 females at each altitude, and their average ages were 31.3+/-7.1 y at 2700 m and 31.2+/-6.8 y at 3700 m, respectively. The resting values of heart rate and mean blood pressure were not significantly different at 2700 m and 3700 m than at sea level. However, increases in these values after exercise were more prominent at high altitudes (heart rate increase = 51.6% at 2700 m and 70.4% at 3700 m; mean blood pressure increase: 19.0% at 2700 m and 17.2% at 3700 m). In addition, post-exercise blood lactate concentration was significantly higher at 3700 m than at sea level or at 2700 m (i.e., 7.6 mM at 3700 m, 3.8 mM at 2700 m, and 4.17 mM at 0 m, respectively). Exercise induced an acute reduction in the arterial oxygen saturation value (SpO2) at 2700 m and 3700 m (i.e., 11.2% reduction at 2700 m and 9.4% at 3700 m), whereas no changes were observed at sea level. The resting values of regional oxygen saturation (rSO2)--measured by a near infra-red spectrophotometer at sea level, 2700 m, and 3700 m-were nearly identical. Exercise at sea level did not reduce this value. In contrast, we observed a decrease in rSO2 after subjects exercised at 2700 m and 3700 m (i.e., 26.9% at 2700 m and 48.1% at 3700 m, respectively). The rSO2 measured 2 min and 3 min after exercise at 3700 m was significantly higher than the preexercise value. From these observations, we concluded that alterations in cardiovascular parameters were apparent only after an exercise load occurred at approximately 3000 m altitude. Acute reduction in cerebral regional oxygen saturation might be a primary cause of headache and acute mountain sickness among unacclimatized trekkers.

Acclimatization↗
PubMedDate not supplied

Enhancement of thermoradiotherapy by glucose administration for superficial malignant tumours.

The effect of hyperglycemia on the thermoradiotherapy of superficial malignant tumours was investigated. Glucose administration alone (500 ml of 10% glucose by intravenous drip infusion) reduced the tumour blood flow, when measured by laser Doppler flowmetry, to 66.1% of the baseline level at 30 minutes after the beginning of glucose infusion. Forty patients received glucose in tandem during the hyperthermia and radiotherapy (group A), and 38 patients received thermoradiotherapy alone (group B). The mean Tave (the average temperature of all intratumoural sensors) in group A was 43.4 +/- 1.1 degrees C while that in group B was 42.5 +/- 1.2 degrees C, i.e., glucose administrations significantly increased the tumour temperature (p < 0.01). In group A, complete tumour response (CR) was observed in 12 patients (30.0%), partial response (PR) in 25 patients (62.5%) and no response (NR) in three patients (7.5%). In group B, seven (18.4%), 20 (52.7%) and 11 (28.9%) patients showed CR, PR and NR, respectively. The tumour response rates were significantly different between two treatment groups (p < 0.05). The frequency of side effects of hyperthermia in groups A and B were 22.5 and 21.1%, respectively. This study suggests that hyperglycemia enhances the effectiveness of thermoradiotherapy.

Adult↗
PubMedDate not supplied

Multidetector-row CT analysis of time-dependent changes in lung fields after chest irradiation: usefulness of precision scans.

Time-dependent changes in lung fields after chest irradiation were analyzed using multidetector-row CT. Routine scans at 3-mm raw thickness and 8-mm recon thickness and precision scans at 0.5-mm raw thickness and 0.5-mm recon thickness were compared with respect to the number of each finding and the time-dependent changes in the rate of each finding. Among the findings visualized by these scans, ground-glass opacity (GGO) showed the highest overall appearance rate. Precision scans exceeded routine scans in the rates of all findings except GGO and confluent shadows, and the two types of scans showed the greatest difference in the rate of GGO. Since we found that GGO tended to be overestimated on routine scans, we confirmed it by a phantom experiment. Precision scans were similar or superior to routine scans in the rates of findings except 3 months after irradiation. We consider that the concomitant use of precision scans is useful in that it allows more accurate evaluation of various post-irradiation changes in lung fields including GGO, in which the lesion is in a reversible stage.

Aged↗
PubMedDate not supplied

Usefulness of circadian amplitude of blood pressure in predicting hypertensive cardiac involvement.

Twenty-four-hour blood pressure (BP) profiles of 56 patients diagnosed as 'hypertensive' by WHO criteria were analyzed by the fit of a 24-hour cosine curve according to the single cosinor method. A left ventricular mass index (LVMI) was also assessed by two-dimensional echocardiography on each patient as a gauge of target organ involvement. LVMI and the BP MESOR correlates positively for systolic, S (r = 0.324), mean arterial, MA (r = 0.334) and diastolic, D (r = 0.267) BP (P less than 0.05), yet no statistically significant linear correlation between LVMI and the circadian BP amplitude (one-half of predictable change) was found. When a second-degree polynomial regression was fitted to the circadian BP amplitudes, an association was found (SBP: R2 = 0.138, P = 0.02; MAP: R2 = 0.167, P = 0.01; DBP: R2 = 0.128, P less than 0.01). The corresponding curves were characterized by peaks in the circadian amplitudes of SBP, MAP and DBP around a value of LVMI between 110 and 120 g/m2. For further scrutiny, three subgroups had been formed on the basis of literature, a priori with respect to the LVMI (group 1: LVMI less than 100); group 2: 100 less than LVMI less than 130; group 3: 130 less than LVMI). For MESORs, there was no difference between groups 1 and 2, whereas the MESOR of group 3 were larger than the other two groups. The circadian BP amplitudes of group 2 were larger than those of the other two groups for SBP, MAP and DBP. An increasing LVMI precedes a definitive increase of BP MESOR and coincides with an increase in the circadian BP amplitude; thus an increase in extent of circadian changes can alert the self-monitoring population of a target organ involvement.

Adolescent↗
PubMedDate not supplied

Repeated alcohol intake changes circadian rhythm of ambulatory blood pressure.

The blood pressure of 7 clinically healthy volunteering social drinkers was studied while they consumed, with a crossover design for 5 days, either 40 g of alcohol by day or fruit juice, with the two spans on alcohol and juice being separated by a one-week washout. Whereas the rhythm-adjusted mean was not changed, a clear statistically significant increase in the circadian double amplitude was found. The study provides a model for a rapidly achieved circadian amplitude hypertension which may precede an elevation of the overall blood pressure mean in the natural course of the disease.

Adult↗