Biomedical subjects

T Moritani

Publications and source records attributed to T Moritani.

At least 37 records · Page 2Linked to original sources

PubMed1999

Aging alteration of cardiac vagosympathetic balance assessed through the tone-entropy analysis.

BACKGROUND: Age-associated alterations of cardiac autonomic functions have been investigated intensively through heart rate variability analyses. However, changes with age in cardiac vagosympathetic balance remain to be elucidated. METHODS: We studied 142 male subjects (30-69 yr) at a health care center in Kyoto, Japan. Electrocardiographic data were collected from subjects in a recumbent position for 10 min in the morning. Analysis was done by classifying the subjects into four age groups. In a pharmacological experiment carried out in December 1996, tone was verified to reflect the cardiac vagosympathetic balance, and entropy the total autonomic neural efferent activity. We assessed the heart rate variability through the tone-entropy (T-E) analysis that was described previously. In essence, two indexes, tone and entropy, were defined on a distribution of successive variations of heart period. RESULTS: No significant differences were detected in clinical conditions among the four age groups. Tone increased and entropy decreased significantly with age. The aging process was expressed as a curvilinear path in T-E space. Compared to the pharmacological experiment, it was observed that aging degenerated the heart function from an ordinary to a denervated one. The same aging path was superimposed in the opposite direction on the heart recovery path after dynamic exercise in which cardiac vagosympathetic balance tended toward vagus division, corresponding with restoration of total autonomic activity. CONCLUSIONS: An age-related reduction in cardiac autonomic function was consistent with previous reports. The vagosympathetic balance was altered with this reduction: vagal predominance was impaired significantly in proportion to the withdrawal of total cardiac autonomic activity.

Adrenergic beta-Antagonists↗

PubMed1999

The association between Trp64Arg polymorphism of the beta3-adrenergic receptor and autonomic nervous system activity.

The beta3-adrenergic receptor plays a significant role in the control of lipolysis and thermogenesis in brown adipose tissue through autonomic nervous system (ANS) activity. As the Trp64Arg polymorphism of the beta3-adrenergic receptor gene might affect ANS activity, we investigated the association of the polymorphism with ANS activity. The prevalence of the polymorphism was determined in 204 subjects. Ten normal homozygous, 10 heterozygous, and 1 variant homozygous subjects were examined for ANS activity during supine rest and standing by electrocardiogram R-R interval power spectral analysis. Subjects with the variant did not differ from subjects without the variant in body mass index, plasma glucose, plasma insulin, or family history of diabetes or obesity. The total power of heterozygotes at supine rest was lower than that of normal subjects (1124.6 +/- 191.6 vs. 3029.8 +/- 758.8 ms2; mean +/- SE). With a postural change to standing, the parasympathetic and sympathetic nervous system activity indexes of heterozygotes showed a higher response than those of normal subjects (parasympathetic nervous system index, 0.10 +/- 0.02 vs. 0.17 +/- 0.02; sympathetic nervous system index, 10.55 +/- 1.47 vs. 6.26 +/- 1.09), and the difference in total power disappeared. These findings show that subjects with the variant, even the heterozygotes, had lower resting ANS activity than normal subjects.

Adult↗

PubMed1999

Successful transcutaneous arterial embolization of a giant hemangioma associated with high-output cardiac failure and Kasabach-Merritt syndrome in a neonate: a case report.

We describe the case of a patient with a neonatal giant cutaneous hemangioma with high-output cardiac failure and Kasabach-Merritt syndrome and successfully treated with transcutaneous arterial embolization aimed at controlling severe congestive heart failure and consumption coagulopathy. A patient was admitted to the neonatal care unit on the first day of age because of a large hemangioma on his right lateral chest wall and respiratory distress, associated with cardiac failure resulting from arteriovenous shunting. On the second day of age the platelet count decreased to 5.7 x 10(4)/microliter and fibrinogen level was 85 mg/dl. The values of prothrombin time and activated partial thromboplastin time were prolonged. Intravenous predonisone therapy was started immediately, but bleeding tendency was getting worse and the evidence of congestive heart failure persisted. On the third day the patient then underwent embolization of feeding arteries with microcoils. The cardiac failure and thrombocytopenic coagulopathy had improved significantly without complications. We conclude that transcutaneous arterial embolization is an effective and safe treatment in this neonate and should be considered for the treatment of control high-output cardiac failure and coagulopathy in infants with hemangioma and Kasabach-Merritt syndrome.

Cardiac Output, High↗

PubMed1998

Further evaluation of physical fitness age versus physiological age in women.

The present study was conducted to examine further whether adult women who are in a state of high physical fitness possess high physiological functions, and also to investigate whether those who exercise regularly are able to maintain a high quality of various physiological functions. The subjects of this study were 249 healthy Japanese adult women (aged 20-70 years). Of these subjects 30 had jogged or walked regularly for more than 3 years. The physiological ages (PA) and physical fitness ages (FA) of the individuals were estimated from 17 physiological function tests and 5 physical fitness tests, respectively, by principal components analyses. The results indicated that there was a significant correlation between PA and FA (r = 0.76, P < 0.01). To examine this relationship in more detail, the subjects were classified into three physical fitness groups (high, normal and low) based on the deviation from the regression line of FA. Comparison of the mean PA among three physical fitness groups revealed that the high physical fitness groups demonstrated a much lower PA (physiologically younger), while the low physical fitness groups showed a relatively higher PA (physiologically older) in spite of their equivalent chronological ages. From this series of studies, a new concept is proposed where different individuals have different peak physiological capacities, but that these capacities change with age at similar rates. It is suggested that interventions such as exercise and a proper diet for promoting health could increase peak functional capacity but have little effect on the rate of decline.

Adult↗

PubMed1998

H-reflex modulations during voluntary and automatic movements following upper motor neuron damage.

OBJECTIVES: It is not known whether similar mechanisms account for the impairments of voluntary movement and automatic postural responses of individuals with spasticity secondary to damage to the sensorimotor cortex and its projections (i.e. upper motor neuron syndrome (UMN)). METHODS: The present study examined changes in soleus H-reflexes preceding and during voluntary tibialis anterior (TA) muscle contraction of standing subjects and during balance platform induced postural perturbations that elicited similar TA muscle contractions. Twenty-two subjects (12 non-disabled; 4 with spastic-type cerebral palsy; 6 with adult-onset cerebral vascular accident) participated in the study. Data were analyzed using ANOVAs and Tukey HSD post-hoc comparison tests to assess the timing and magnitude of soleus H-reflex amplitude changes relative to the onset of TA muscle activation. RESULTS: Results indicated that, regardless of the level of TA activation, soleus H-reflexes of subjects with UMN involvement did not demonstrate inhibition either. during voluntary movements or during automatic postural perturbations. CONCLUSIONS: These findings indicate that postural reflexes, as well as volitional movements, are impaired following UMN damage and that deficits in neural pathways subserving reciprocal inhibition contribute to the impairments.

Adult↗

PubMed1998

1998 ISEK Congress Keynote Lecture: The use of electromyography in applied physiology. International Society of Electrophysiology and Kinesiology.

Electromyogram (EMG) analyses (surface, intramuscular and evoked potentials) in studies of muscle function have attracted increasing attention during recent years and have been applied to assess muscle endurance capacity, anaerobic and lactate thresholds, muscle biomechanics, motor learning, neuromuscular relaxation, optimal walking and pedalling speeds, muscle soreness, neuromuscular diseases, motor unit (MU) activities (MU recruitment and rate coding), and skeletal muscle fatigue. This paper deals with the use of EMG analyses employed in the area of applied physiology and is divided into three sections: surface EMG analyses; intramuscular EMG analyses; and evoked potential analyses.

Adaptation, Physiological↗

PubMed1998

Neuromuscular, metabolic, and kinetic adaptations for skilled pedaling performance in cyclists.

PURPOSE: The purpose of this study was to clarify the reason for the difference in the preferred cadence between cyclists and noncyclists. METHODS: Male cyclists and noncyclists were evaluated in terms of pedal force, neuromuscular activity for lower extremities, and oxygen consumption among the cadence manipulation (45, 60, 75, 90, and 105 rpm) during pedaling at 150 and 200 W. Noncyclists having the same levels of aerobic and anaerobic capacity as cyclists were chosen from athletes of different sports to avoid any confounding effect from similar kinetic properties of cyclists for lower extremities (i.e., high speed contraction and high repetitions in prolonged exercise) on both pedaling performance and preferred cadence. RESULTS: The peak pedal force significantly decreased with increasing of cadence in both groups, and the value for noncyclists was significantly higher than that for cyclists at each cadence despite the same power output. The normalized iEMG for vastus lateralis and vastus medialis muscles increased in noncyclists with rising cadence; however, cyclists did not show such a significant increase of the normalized iEMG for the muscles. On the other hand, the normalized iEMG for biceps femoris muscle showed a significant increase in cyclists while there was no increase for noncyclists. Oxygen consumption for cyclists was significantly lower than that for noncyclists at 105 rpm for 150 W work and at 75, 90, and 105 rpm for 200 W work. CONCLUSIONS: We conclude that cyclists have a certain pedaling skill regarding the positive utilization for knee flexors up to the higher cadences, which would contribute to a decrease in peak pedal force and which would alleviate muscle activity for the knee extensors. We speculated that pedaling skills that decrease muscle stress influence the preferred cadence selection, contributing to recruitment of ST muscle fibers with fatigue resistance and high mechanical efficiency despite increased oxygen consumption caused by increased repetitions of leg movements.

Adaptation, Physiological↗

PubMed1998

Spontaneous regression of localized neuroblastoma detected by mass screening.

PURPOSE: To clarify whether and when neuroblastomas identified through screening do regress, and to ascertain how to treat them appropriately, we observed screened patients who had localized tumors, without any therapeutic intervention. PATIENTS AND METHODS: The criteria for the observation program were as follows: disease stage I or II; tumor less than 5 cm in diameter; no invasion to the intraspinal canal or growth to the great vessels; urinary vanillylmandelic acid (VMA) and homovanillic acid (HVA) less than 50 microg/mg creatinine; and informed consent. Of 25 patients identified through screening for 6-month-old infants in Saitama Prefecture, Japan between April 1994 and March 1996, 11 patients who met the criteria and one other patient with stage III tumor were enrolled onto the program. They were examined by abdominal ultrasonography (US) and their urinary VMA and HVA levels were assessed approximately once per month. The observation periods ranged from 4 to 27 months. RESULTS: The 11 tumors decreased in size, although one of these 11 tumors initially enlarged until the patient was 12 months of age and decreased in size thereafter. One other tumor slightly increased in size. Urinary VMA levels decreased in all patients. None of the tumors had completely disappeared by the last observation day. CONCLUSION: Our results suggest that regression of screened neuroblastoma is not a rare phenomenon. At present, it seems reasonable to adopt a wait-and-see strategy, with careful observation, for selected stage I or II tumors identified in infants screened at 6 months of age.

Homovanillic Acid↗

PubMed1998

Primary cardiac angiosarcoma with superior vena caval syndrome: review of surgical resection and interventional management of venous inflow obstruction.

Primary cardiac angiosarcoma occurs rarely, and surgical resection is often required to relieve symptoms. A 66-year-old man whose presenting symptoms were palpitations and general fatigue is presented. Echocardiography revealed a large tumour occupying most of the right atrium. When superior vena caval (SVC) syndrome developed, surgical resection of the tumour was attempted. The tumour was found to have invaded the inflow of SVC, left atrium, right ventricle and ascending aorta. The bulk of the tumour was resected, requiring reconstruction of the right atrium and caval inflows. Histopathological diagnosis of the tumour was primary angiosarcoma. In the postoperative period, symptoms of SVC syndrome recurred, which were relieved temporarily by balloon angioplasty. After one month, recurrence of symptoms was again managed by catheter dilation. On this occasion a metallic stent was deployed, which prevented further symptoms of SVC syndrome during the eight months before the patient died with generalized metastases.

Aged↗

PubMed1997

Determination of the optimal walking speed for neural relaxation in healthy elderly women using electromyogram and electroencephalogram analyses.

The purpose of this study was to determine the walking speed which has the greatest influence on neural relaxation in healthy elderly women as determined by electromyogram (EMG) and electroencephalogram (EEG) analyses. Seven elderly female volunteers [mean age 68.5 (SD 3.95) years] served as subjects for this study. The EMG signals were recorded from the gastrocnemius (MG), soleus (SL) and tibialis anterior (TA) muscles while walking on a treadmill, starting at 40 m.min-1 and increasing 6 m.min-1 incrementally for 10 min. The turning point of muscle activities (by integrated EMG. iEMGtp) was determined as the walking speed at the point at which the mean rate of change of iEMG (MG + SL + TA) abruptly increased. After the determination of iEMGtp. the treadmill was set at three constant speeds, one corresponding to the speed for the iEMGtp and two others 20% higher or lower than that for the iEMGtp. The subjects then walked for 20 min at each of these speeds on 3 separate days and their EEG power spectrum data were obtained for frequencies from the 8 to 13 Hz (z-wave component, AWC). The mean of iEMGtp for our subjects was at a mean walking speed of 64.7 (SD 7.9) m.min-1. Considering the subjects' age and height, iEMGtp was somewhat faster than their expected self-paced normal walking speed. There were no differences between the mean AWC values of the subjects prior to exercising at each of the three speeds. The mean AWC values after exercise were significantly (P < 0.01) greater than before. The extent of the increase in AWC at iEMGtp was greater than those at slower speeds. Our data would suggest that walking exercise at the speed which corresponds with EMG evidence of iEMGtp may induce the most significant relaxing effects in elderly women.

Aged↗

PubMed1997

Effects of combined beta-adrenergic and cholinergic blockade on the initial ventilatory response to exercise in humans.

To elucidate whether combined adrenergic and parasympathetic blockade would affect the ventilatory response to exercise, especially at the initial stage (phase I), six healthy subjects performed a brief and light voluntary bilateral leg extension exercise and passive movements under the conditions of control (before the blockade) and after intravenous administration of combined beta-adrenergic (propranolol, 0.2 mg.kg-1) and muscarinic (atropine, 0.04 mg.kg-1) receptor antagonists. The movements were continued only within two breaths after the onset of the motion. Ventilation increased immediately and significantly (P < 0.05) within the first breath at the onset of voluntary exercise in all conditions as compared with at rest. However, the magnitude of increase in mean ventilation within two breaths at the start of exercise as against the resting value (delta ventilation) was significantly less (P < 0.05) after the combined blockades (2.5 l.min-1) than in the control condition (3.7 l.min-1). Passive movements showed a similar but smaller change as compared with voluntary exercise. The heart rate response to exercise was attenuated by the combined blockade while cardiac output showed a slight change at the onset of exercise. It is concluded that phase I should occur despite the inhibited activity of the beta-adrenergic and the cholinergic systems; nevertheless, the response was attenuated by the combined blockade. These results suggest a possible role of the beta-adrenergic and/or cholinergic systems in the rapid increase in ventilation that occurs at the start of exercise.

Adrenergic beta-Antagonists↗

PubMed1997

Caffeine enhances modulation of parasympathetic nerve activity in humans: quantification using power spectral analysis.

We investigated changes in autonomic nerve activity following caffeine intake by power spectral analysis of R-R intervals of heartbeats in humans. A beverage containing 240 mg of caffeine or a control beverage was given to 10 healthy volunteers, and R-R intervals were measured while subjects were sitting and controlling their respiration at a constant rate. After consumption of the caffeine-containing beverage, a transient and significant increase (P < 0.001) in spectral integrated values (areas under the curve) of high frequency power (high component, HC) was observed, and at 30 min the value was significantly greater than in controls (P < 0.02), suggesting an increase in vagal autonomic nerve activity. The effect of caffeine was also examined using decaffeinated coffee supplemented with exogenous caffeine (2 mg/kg body wt). A transient and significant increase (P < 0.0001) in HC was observed, and the value was significantly greater (P < 0.02) than when subjects consumed decaffeinated coffee without supplemental caffeine. The ratio of HC to total integrated value (which is also used as a selective indicator of vagal activity) was also significantly higher (P < 0.04) after caffeine consumption. Physiological variables accompanying the change in autonomic nerve activity (i.e., blood pressure, surface body temperature and heart rate) were not significantly affected by caffeine intake. These results suggest that power spectral analysis of heartbeat R-R intervals is an effective and noninvasive method for detecting subtle changes in autonomic nerve activity in response to food intake.

Adult↗

PubMed1997

Tone-entropy analysis on cardiac recovery after dynamic exercise.

Autonomic controls on heart rate variability have been investigated; however, sympathovagal interactive modulations remain unexplored. The purpose of this study is to present a new method, tone-entropy analysis (T-E analysis) of heart period fluctuations, and to make clear an intensive cooperation of autonomic networks in heart recovery. On the basis of evidence obtained in animal experiments, we hypothesized that heart periods are lengthened or shortened beat to beat by assumed physiological mediators: accelerator and inhibitor. Their operations were evaluated through a normalized successive variation of the period, that is, the percentage index (PI). The process was described through PI distributions by using two indexes, tone and entropy, standard values of which were obtained through pharmacological autonomic blockade experiment. T-E analysis was applied to heart recovery (70 min) after dynamic exercise by 12 female athletes. Interactive autonomic modulations were expressed by a curved path in tone-entropy space. Results suggested that heart rate decay proceeds not by withdrawal of one pathway but by increasing activity of both pathways as vagosympathetic balance inclines slightly but significantly to the vagus division in the course of recovery. The process was examined through Fourier spectral analysis as well.

Adult↗

PubMed1996

Effects of habitual physical exercise on physiological age in men aged 20-85 years as estimated using principal component analysis.

A population of 221 healthy adult men (aged 20-85 years) was studied to determine whether those who exercised regularly were in good biological condition, and also whether those who were in a state of high physical fitness were in a good state biologically, in terms of physiological age (PA) and physical fitness age (FA) as estimated by principal component analysis. A group of 17 physiological function tests and 5 physical fitness tests were employed to estimate PA and FA, respectively. The results of this study indicated that those who maintained high physical fitness at all age decade groups from 20 to 79 years had a trend towards maintaining a relatively lower PA (physiologically younger). Mean PA and FA of the trained group were younger by 4.7 and 7.3 years, respectively than those of the untrained group. In addition, the slope of regression line of PA on chronological age was more gentle in the trained group than that in the untrained group. These results would suggest that those who are in a state of high physical fitness maintain a relatively good physiological condition, and that regular physical exercise may delay physiological changes normally seen with aging, and consequently may increase the life span.

Adult↗

PubMed1996

Interlimb co-ordination of force and movement-related cortical potentials.

The question we asked in this study was how the cerebral hemispheres are coordinated when the two hands simultaneously generate force at the same level. Interlimb co-ordination of contractions at 20% of the maximal level was investigated during bilateral (BL) and unilateral (UL) handgrip in eight male right-handed subjects. The accuracy as determined by the force error was larger during BL than during UL for the left hand only. The movement-related cortical potential (MRCP) of C3 (left precentral cortex) was studied during UL right and BL handgrip and the C4 (right precentral cortex) during UL left and BL handgrip. At the phase of the readiness potential (-1.0 to -0.6 s prior to the force onset), similar levels of correlation in the C3 (C4) MRCP amplitudes (P < 0.05) between UL right (UL left) and BL handgrip were observed. At the phase of the negative slope (-0.6 to -0.2 s) and the motor potential (-0.2 to -0.05 s), C3 revealed almost the same levels of correlation as for the readiness potential, whereas in C4 a marked decrease was noted. Accordingly, from this study the force error and movement-related cortical potentials would indicate that the left dominant hemisphere is specialized not only for unilateral contractions but also for bilateral contractions.

Adult↗

PubMed1996

Cross-correlation studies of movement-related cortical potentials during unilateral and bilateral muscle contractions in humans.

A useful method of studying the degree of association between two signals of varying amplitude in the time domain is to use cross-correlation analysis. We applied this to the movement-related cortical potentials digitally filtered so as to eliminate the low frequency component before applying it during maximal unilateral left (UL L), unilateral right (UL R) and bilateral (BL) contractions in 11 right-handed subjects. The recording electrode sites were over the right and left motor cortex areas (C3 and C4). The BL condition revealed higher cross-correlation levels of cortical activities between the two hemispheres than in UL L or UL R contraction [UL L, r = 0.68 (SEM 0.05); UL R, r = 0.73 (SEM 0.03); BL, r = 0.76 (SEM 0.02)]. The UL R revealed a positive phase difference [5 (SEM 2) ms] when the maximal cross-correlation coefficient was shown and UL L showed a negative phase difference [5 (SEM 3) ms]. However, BL revealed a smaller phase difference [2 (SEM 1) ms] than that for UL. It was concluded that during maximal BL contraction cortical cellular activities in both hemispheres was more synchronized in amplitude and time course compared with maximal UL contractions. Our data suggested that central common drive existed between the right and left motor areas during the maximal BL handgrip contractions and the amplitude of potentials of both hemispheres was modified by the interhemispheric inhibition mechanism as reported in other studies.

Adult↗

PubMed1996

Hypomelanosis of Ito associated with neuroblastoma.

We report a patient with hypomelanosis of Ito associated with neuroblastoma. Though not previously reported, the association is plausible since both conditions are forms of "neurocristopathy".

Adrenal Gland Neoplasms↗

PubMed1996

Protective effect of dipyridamole against lethality and lipid peroxidation in liver and spleen of the ddY mouse after whole-body irradiation.

The effects of dipyridamole on radiation damage in the mouse were investigated. Dipyridamole (i.p. 2 mg/mouse) administered 1 h before exposure, protected against gamma-irradiation. Pretreatment significantly decreased the death rate at 30 days from 89 to 33% (p<0.001) after 9 Gy whole-body irradiation. LD50 at 30 days was increased from 6.67 to 7.65 Gy in the dipyridamole pretreated group. The level of thiobarbituric acid reactive substances (TBARS) in the liver and spleen, a measure of free radical initiated liver peroxidation, increased 155, 193, 195, and 236% of control (without irradiation) in liver, and 132, 146, 168, and 276% of control (without irradiation) in spleen on days 2, 4, 7, and 10 after 9 Gy of whole-body irradiation respectively. The TBARS levels in both liver and spleen 2 days after irradiation were reduced to 73 +/- 7 and 60 +/- 19% respectively after dipyridamole treatment (2 mg/mouse, i.p. injection 1 h before exposure). In electron microscopic studies, mitochondria and endoplasmic reticulum in the irradiated mouse liver were swollen, but otherwise appeared normal after dipyridamole treatment. These results suggest that dipyridamole has a protective effect on animal survival 30 days after 60Co gamma-irradiation and inhibits lipid peroxidation - which is thought to play a part in the radiation injury in mouse liver and spleen.

Animals↗