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Biomedical subjects

M Miyamura

Publications and source records attributed to M Miyamura.

At least 55 records · Page 3Linked to original sources
PubMed1993

Cardiorespiratory response at the onset of passive leg movements during sleep in humans.

To examine the ventilatory response at the onset of passive leg movements during sleep in man and the concomitant changes in cardiac output (Qc), five healthy male subjects had their knee joints extended and flexed alternately at a frequency of about 60.min-1 for about 8 s. Minute ventilation (VI), respiratory frequency, tidal volume, end-tidal partial pressure of carbon dioxide and of oxygen, stroke volume (SV), heart rate (fc) and Qc were measured before, during and after passive leg movement during sleep stage III or IV (SLEEP). These values were compared with those of the awake condition (AWAKE). The VI increased significantly (P < 0.05) compared with the mean of five breaths preceding the movement (pre-movement) within one or two breaths at the onset of passive leg movements in both conditions. The difference between the mean of the first and second breaths after the onset of leg movement and pre-movement was 5.2 (SEM 1.9) l.min-1 for SLEEP and 2.7 (SEM 1.1) l.min-1 for AWAKE, respectively. Four of the five subjects showed a larger increase in ventilation during SLEEP compared with AWAKE. The fc increased significantly (P < 0.05) at the beginning of the passive movement in all cases, while SV showed an increase or decrease so that Qc showed no significant change in either condition. These results would suggest that afferent drive from moving limbs could produce an increase in ventilation without any change in Qc.

Adult↗
PubMed1992

Influence of time of administration of a Shosaiko-to extract granule on blood concentration of its active constituents.

Using a Shosaiko-to extract granule, we investigated the effects of the timing of administration (orally, before and after a meal) on the plasma concentration of its active constituents, glycyrrhizin (GL), baicalin, baicalein and glycyrrhizic acid (GA), a metabolite of GL. The pattern of plasma concentration change of GL differed between the two times of administration, and followed a two-phase pattern when the granules were taken before meals. There was no difference neither in the area under the plasma concentration-time curve (AUC) between the two periods, nor AUC itself. GA showed no difference in plasma concentration pattern, nor was baicalin detected in the plasma following administration by either method. The plasma concentration pattern of baicalein differed between the two timings but followed that of the two-phase pattern in each case. The plasma concentration pattern of active constituents of Shosaiko-to extract granule varied with the time of administration, but there was no significant difference in the maximum plasma concentration or AUC of active constituents depending on the administration. We concluded that the present clinical timing of administration of Shosaiko-to should be determined on the basis of patient compliance and other relevant factors.

Administration, Oral↗
PubMed1992

Effects of blood gas, pH, lactate, potassium on the oxygen uptake time courses during constant-load bicycle exercise.

Changes in the time courses of VO2 during constant-load exercise were examined in connection with other cardiorespiratory and blood chemical parameters. Eleven healthy male subjects performed a ramp exercise and three to six constant-load exercises at varying degrees of load using an electro-braked bicycle ergometer. Heart rate, ventilation, and gas exchange were measured during both types of exercise, and chemical parameters of the subject's blood (blood gas, pH, lactate, and electrolytes) were determined during two intensities of constant-load exercise. The time courses of cardiorespiratory and blood chemical data 3 min after the onset of constant-load exercise were fitted by linear regressions to see whether these parameters had reached the steady state or not. Heart rate increased significantly at a lower intensity of constant-load exercise than VE, VO2, and VCO2. While the increase in VCO2 was slower than that of VO2, a definite difference in time courses was not found between VE and VO2. The time courses of changes in blood gas, pH, bicarbonate, and lactate were not correlated with those of VO2. However, changes in blood potassium concentration were closely correlated with those of VO2 in terms of time courses and magnitude. This suggests the possibility that blood potassium may play an important role in the control of VO2 time course during constant-load exercise.

Adolescent↗
PubMed1992

Ventilatory response to the onset of passive and active exercise in human subjects.

Ventilatory responses at the onset of passive and active exercise with different amount of exercising muscle mass were studied in 10 healthy male subjects. Four exercise tests were performed for each subject with appropriate intervals on the same day, i.e., two voluntary exercises of one leg or both legs and two passive exercises of one leg or both legs. Inspiratory minute volume (VI), end-tidal CO2 and O2 partial pressures (PETCO2, PETO2) were measured breath-by-breath using a hot-wire flowmeter, infrared CO2 analyzer, and a rapid O2 analyzer. Average values of VI were obtained from 5 breaths at rest preceding exercise and the first and second breaths after the onset of exercise. The ventilatory response to exercise was calculated as the difference (delta) between the mean of exercise VI and mean of resting VI. In this study, the PETCO2 decreased by about 0.5 Torr in four exercise tests, though the decrement of PETCO2 was not statistically significant. The average values and standard deviation of delta VI were 4.22 +/- 1.63 l/min for the one leg and 6.46 +/- 1.80 l/min for the two legs in the active exercise, and were 2.46 +/- 1.12 l/min for the one leg and 3.44 +/- 1.55 l/min for the two legs in the passive exercise, respectively. These results suggest that in awake conditions, the ventilatory response at the onset of passive or active exercise does not increase additively with the increasing amount of muscle mass being exercised.

Adolescent↗
PubMed1992

Effects of acute hypoxia on ventilatory response at the onset of cycle exercise in man.

In order to examine whether or not there are initial changes in ventilation at the start of bicycle exercise having work loads of differing intensities are affected with regard to normoxia and to hypoxia accompanying hypocapnia, six healthy male subjects performed submaximal exercise of 30 and 120 W at 60 rpm under normoxic (FIO2 = 0.21) and hypoxic (FIO2 = 0.11) conditions. Resting ventilation was significantly higher in hypoxia than in normoxia. However, no statistically significant differences in the initial change in ventilation at the start of exercise (delta VI assessed breath-by-breath) were found between eucapnic normoxia and hypocapnic hypoxia in both 30 and 120 W exercise. Moreover, blood lactate after exercise did not increase in any conditions as compared with rest. These observations suggest that the neurogenic ventilatory response immediately after submaximal exercise at a work load below the subject's anaerobic threshold is independent from PO2.

Adult↗
PubMed1992

The effects of leg-cooling on blood lactate disappearance following supramaximal exercise.

In order to clarify whether leg-cooling after supramaximal treadmill exercise will change lactate disappearance rate from venous blood, blood lactate, calf blood flow, and skin temperature were determined in cold application and non-cold application recovery. In the cooling experiments, both legs were cooled with ice packs for 23 min during recovery. The skin temperature was significantly lower in the cold application as compared with the non-cold application. However, no significant difference was found in the blood lactate and/or calf blood flow between cold and non-cold conditions. In addition, there was no significant difference in the slope of regression line (blood lactate/blood flow) between cold and non-cold applications. These results suggest that no significant difference in the blood lactate between cold and non-cold applications could be explained by the lack of difference in the blood flow between cold and non-cold applications.

Adult↗
PubMed1992

[Palilalia and acquired stuttering in a case of Parkinson's disease].

We report palilalia and acquired stuttering in a 60-year-old Japanese male with Parkinson's disease. At the age of 54, he presented with resting tremor in the hand and foot on the left, and gradual slowness in voluntary movements. Two years later, resting tremor involved the right foot, and an expressionless face and frozen gait occurred. A diagnosis of Parkinson's disease was made and treatment with L-dopa and carbidopa resulted in conspicuous improvement. At the age of 57, he developed compulsive repetitions of syllables, words and phrases, and sentences infrequently when he spoke. They have been persisting for four years. Repetitions increased in spontaneous speech while they decreased in oral reading and repetition of sentences. These repetitions in speech were symptomatologically diagnosed as palilalia and acquired stuttering. Brain CT showed slight brain atrophy, and brain MRI disclosed a few lesions indicating lacunae in the left substantia nigra, left putamen, and right internal capsule. SPECT showed a slight decrease in blood flow in the frontal lobes and basal ganglia bilaterally. Full IQ on WAIS was 105, and neither agnosia nor apraxia was detected. Palilalia and acquired stuttering, though the pathomechanism has not been clarified, have been reported to occur usually secondary to cerebral vascucular lesions and very rarely in Parkinson's disease. In the present case, they may have been produced by the parkinsonian nigro-striatal lesions. Alternatively, they may have been induced by the small vascular lesions demonstrated by MRI.

Atrophy↗
PubMed1990

Adaptive changes in hypercapnic ventilatory response during training and detraining.

To confirm the effects of physical training and detraining on CO2 chemosensitivity, we followed hypercapnic ventilatory response at rest in the same five subjects during pre-, post- and detraining for 6 years. They joined our university badminton teams as freshmen and participated regularly in their team's training for about 3 h a day, three times a week, for 4 years. After that they retired from their teams and stopped training in order to study in the graduate school for 2 years. Maximum pulmonary ventilation (VEmax) and maximal oxygen uptake (VO2max) for each subject were determined during maximal treadmill exercise. The slope (S) of ventilatory response to carbon dioxide at rest was measured by Read's rebreathing method. Mean values of VEmax increased statistically during training and decreased statistically during detraining. A similar tendency was observed in VO2max. The average value of S before training was 1.91 l.min-1.mmHg-1, (+/- ) SD 0.52 and it decreased gradually with increasing training periods; the difference between the S values before (1980) and after training (1982, 1983 and 1984) were all significant. Furthermore, the mean values of S increased significantly during detraining as compared with those obtained at the end of training (April 1984). We concluded that in normal subjects, long-term physical training increases aerobic work capacity and decreases CO2 ventilatory responsiveness, and that the ventilatory adaptations with training observed here are reversible through detraining.

Adaptation, Physiological↗
PubMed1990

Effects of acute hypoxia on ventilatory response at the onset of submaximal exercise.

In order to investigate the effects of acute hypoxia and accompanying hypocapnia on the ventilatory response at the onset of dynamic exercise, four healthy adult men performed 50W rectangular loads on a cycle-ergometer in normoxic (FIO2 = 0.21) and hypoxic (FIO2 = 0.11) conditions. No statistically significant differences in the initial ventilatory responses to exercise (both delta VI and delta VE assessed on a breath-by-breath basis) were found between eucapnic normoxia (PETO2 approximately 95, PETCO2 approximately 42 Torr) and hypocapnic hypoxia (PETO2 approximately 45, PETCO2 approximately 35 Torr). The present findings support the contention that the neurogenic ventilatory drive at the onset of early exercise is independent from PO2 and PCO2.

Adult↗
PubMed1990

Seasonal variations of ventilatory response to hypercapnia at rest.

In order to examine the seasonal variation of CO2 sensitivity, the slope (S) of the ventilatory response to CO2 was determined in 10 healthy males throughout a year. It was found that the average value of logarithm S was significantly (p less than 0.05) higher in the September than in the annual average, though average magnitude of S was not significantly different. In addition, the average value of ventilation (VE(60] corresponding of PACO2 60 mmHg was significantly (p less than 0.05) lower in January than in September. These results indicate that the timing of the start and/or finish of training is an important factor in the effect of physical training on the S and VE(60).

Adolescent↗
PubMed1989

[Effects of carbon dioxide inhalation prior to maximal exercise on blood lactate and physical performance].

In order to examine the effect of acute respiratory acidosis induced by CO2 inhalation prior to maximal exercise on blood lactate and physical performance, double determinations were carried out for each subject on separate days; one day, after CO2 inhalation and other day, after inhalation of room air. It was observed that in the untrained subjects the CO2 inhalation prior to maximal treadmill exercise does not affect endurance time and maximum aerobic power, whereas blood lactate during recovery was lower in CO2 breathing than that in room air. In addition, no significant difference of 200m sprint time in the athletes was noticed between CO2 and room air while blood lactate after 200m sprint running was significantly lower in the CO2 than that in room air. From these results, it was suggested that the effect of CO2 inhalation prior to maximal exercise as applied here appeared to be mediate through metabolic rather than oxygen transport mechanism, but not related to physical performance.

Acidosis, Respiratory↗
PubMed1988

Development of a telemetry system for measuring oxygen uptake during sports activities.

A new system for continuous measurement of oxygen uptake by means of a telemeter has been developed. Oxygen uptake and pulmonary ventilation during rest and exercise were determined using a portable oxygen consumption meter (Oxylog). A small interface circuit between the Oxylog and the transmitter of a frequency modulated bio-telemeter system was designed and installed inside the Oxylog. Data from the transmitter were passed to a receiver and were fed into a microcomputer system. The microcomputer system displayed and printed out minute values of ventilation and oxygen uptake. The accuracy and reliability of the new system were checked by comparison with the traditional (Douglas bag) method. In the range less than 80 l.min-1 of ventilation and less than 2 l.min-1 of oxygen uptake, the system was not inferior to the Douglas bag method. The new system was applied for field continuous measurement of oxygen uptake during a doubles tennis game. The results of the application indicate that the telemetry system developed here is a very practical and useful way of measuring oxygen uptake during sports activities.

Adult↗
PubMed1988

Sex differences in lactate and glycerol levels during maximal aerobic and anaerobic running.

Lactate, glycerol, adrenaline, and noradrenaline in venous blood following 400 m and 3000 m runs were measured in 6 untrained male students, 5 female handball players, 6 female sprinters and 6 female long-distance runners. Physical performance in the two events by the untrained males was the same as for the female handball players, but was less than that by the female sprinters and female long-distance runners. Peak blood lactate levels obtained after 400 m sprinting, and glycerol concentration following the 3000 m run were not significantly different between the untrained males and the female handball players. On the other hand, both peak blood lactate concentrations after 400 m sprinting for female sprinters and peak blood glycerol levels following a 3000 m run for female long-distance runners were significantly higher than those in the untrained male subjects. In both runs there was no significant difference in adrenaline and noradrenaline between the untrained male group and the female handball players. These results suggest that blood lactate in a 400 m run, and glycerol in a 3000 m run might be a reflection of physical performance level but not of sex difference.

Aerobiosis↗
PubMed1988

Effects of prolonged physical training on ventilatory response to hypercapnia.

In order to determine whether or not resting ventilatory response to hypercapnia is changed by physical training, we studied the effect of long-term physical training on the slope of ventilatory response to CO2 at rest. The subjects were 9 untrained freshmen ranging in age from 18 to 20 years. Five out of nine subjects belonged to the badminton team after entering university in April 1980, and participated in their team's training for about 3 hr per day, 3 times a week year round for about 4 years until March 1984. Maximum oxygen uptake (VO2max), maximum pulmonary ventilation (VEmax) and maximum heart rate (HR max) were determined during maximal treadmill exercise before and after training. The slope (S) of ventilatory response to carbon dioxide at rest was measured by Read's rebreathing method. VO2max increased after training in the trained subjects and mean values of VO2max which were measured in 1982, 1983, and 1984, were statistically higher than that of 1980. Similar tendency was observed in VEmax and VO2max/W. Average values and standard deviations of S before training were 1.91 +/- 0.52 liter/min/torr and were decreased gradually with increasing training period; the differences in the S value before (1980) and after training, i.e., 1982, 1983, and 1984, were all significant. Such difference could still be seen after S was recalculated as SN by using normalized ventilation for 70 kg body weight, while there were no significant differences in the S and SN between baseline and repeated studies in the untrained group. In addition, CO2 responsiveness was found to correlate negatively with maximum oxygen uptake in 4 out of the 5 trained subjects. These results suggest that in normal subjects, long-term physical training, as in the present study, decreases CO2 responsiveness at rest.

Adolescent↗
PubMed1988

Effects of CO2 inhalation prior to maximal exercise on physical performance.

In the untrained subjects, inhalation of 4.5-6.0% CO2 prior to maximal treadmill exercise does not affect physical performance and maximum oxygen uptake, while blood lactate levels during recovery have a tendency to greater decrease in CO2 breathing than that in the room-air breathing. It was suggested that CO2 inhalation immediately prior to maximal exercise as applied here is not a useful tool in increasing physical performance.

Adolescent↗