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Biomedical subjects

H Yamabayashi

Publications and source records attributed to H Yamabayashi.

At least 19 recordsLinked to original sources
PubMed2001

Effects of age on muscle energy metabolism and oxygenation in the forearm muscles.

PURPOSE: The effects of aging on muscle metabolism and oxygenation have not yet been elucidated. We evaluated the effects of aging on energy metabolism and oxygenation in sedentary healthy subjects by simultaneously measuring 31P-magnetic resonance spectroscopy (MRS) and near-infrared spectroscopy (NIRS). METHODS: Nine young (28.1 +/- 5.0 yr) and nine older (61.4 +/- 4.6 yr) healthy subjects were studied. The 31P-MR spectrum was obtained every 15 s during and after hand gripping exercise. Intracellular pH (pHi) and PCr/(PCr+Pi) [PCr: phosphocreatine, Pi: inorganic phosphate] were calculated as an index of energy metabolism. The time constant of the PCr/(PCr+Pi) recovery (tau PCr) was calculated. With NIRS, we evaluated the recovery rates of oxygenated (RHbO2) and deoxygenated hemoglobin (RHb) during the initial 10 s of recovery. RESULTS: The PCr/(PCr+Pi) and pHi at rest and at completion of the exercise and tau PCr did not differ between young and older subjects. However, RHbO2 and RHb were significantly slower in older subjects than in young subjects. CONCLUSIONS: The results suggest that muscle energy metabolism in the forearm muscle was not affected by aging. The slower RHbO2 and RHb in older subjects suggested impaired O2 supply, which was probably due to impaired peripheral circulation caused by the process of aging.

Adult↗
PubMed1997

Nuclear magnetic resonance study of lung water compartments in the rat.

Nuclear magnetic resonance transverse relaxation time (T2) was previously measured in studies of lung water. The T2 decay curves for peripheral lung tissue were found to be multiexponential with two T2 components: T2 fast (T2f) and T2 slow (T2s). This behavior was explained by the compartmentalization of water, in which the protons of water are restricted and do not undergo rapid exchange between the compartments. We investigated the origin of the water for these T2 components using excised rat lungs. The effect of magnetic field inhomogeneity due to air-tissue interfaces was examined by degassing some lungs. The contribution of intravascular water was examined by perfusing the lungs with oil or NaCl solutions. Degassing produced a greater increase in the T2f than the T2s component, indicating that the water in the alveolar walls exposed to air spaces contributed to the T2f. Perfusion with oil decreased the T2s, indicating that intravascular water contributed to the T2s component. The effects of intravascular osmotic pressure on the T2f and T2s components suggest that intracellular water is related to the T2f component.

Air↗
PubMed1996

Magnetic resonance relaxation times in acute hydrostatic pulmonary edema induced by noradrenaline in rats.

Models of pulmonary edema have been used to study the nuclear magnetic resonance (NMR) characteristics of lung water. Several investigators have measured changes in the relaxation times in the permeability type of pulmonary edema, but relatively few have measured relaxation times in the hydrostatic type of pulmonary edema. In this study we determined the characteristics of NMR relaxation times T1, T2 (Hahn spin-echo decay) and water content in acute hydrostatic pulmonary edema induced by noradrenaline administration in rats. Changes in T1 and T2 showed a significant prolongation in hydrostatic pulmonary edema. T2 decay curves for peripheral lung tissues were multiexponential and fit two components [T2 fast (T2f) and T2 slow (T2s)]. With two-component T2 analysis, T2s showed greater prolongation than did T2f. The increase in T2s was significantly correlated with an increase in water content, but the increase in the T2f value was not correlated with water content or with a change in T2s. The T2s component, which likely reflected changes in interstitial water, was more closely related than the T2f component to an increase in water content in hydrostatic pulmonary edema. Results suggested that regional changes in hydrostatic pulmonary edema may be evaluated by multicomponent T2 analysis.

Animals↗
PubMed1995

Muscle energy metabolism and nutritional status in patients with chronic obstructive pulmonary disease. A 31P magnetic resonance study.

We investigated the relationship between nutritional status and muscle energy metabolism during exercise in 18 male patients with chronic obstructive pulmonary disease (COPD) and 15 male control subjects using 31P nuclear magnetic resonance spectroscopy (31P-MRS). The patients and control subjects were further categorized as in either a well-nourished (% ideal body weight, % IBW > or = 90) or malnourished (% IBW < 90) state. Muscle energy metabolism was evaluated by determining the ratios PCr/(PCr + Pi) (PCr, phosphocreatine; Pi, inorganic phosphate), and ATP/(PCr + Pi + ATP). The exercise consisted of repetitive hand grips performed against a load. The work rate was normalized for the individual's lean muscle mass by dividing work performed by the forearm fat-free cross-sectional area, which was calculated using 1H-MRS. The PCr/(PCr + Pi) values during exercise did not correlate with the % IBW in any of the groups of control subjects or COPD patients. Furthermore, the PCr/(PCr + Pi) did not correlate with the normalized work rate in either the well-nourished or malnourished subject groups. However, there were correlations within the groups of control subjects and COPD patients. The PCr/(PCr + Pi) values for the normalized work rate were consistently lower in the COPD patients than in the control subjects. These findings suggest that the altered muscle metabolism in COPD patients is not affected by their nutritional status.

Adenosine Triphosphate↗
PubMed1994

Tissue characterization of pneumonia and irradiated rat lungs with magnetic resonance relaxation times.

To interpret the MRI signal intensities, the T1 and T2 values were determined in vitro for rat lungs with radiation pneumonitis, fibrosis or pneumonia, and also for muscle and fat tissues. The transverse magnetization decays mentioned above exhibited two components, a T2 fast (T2f) and a T2 slow (T2s) component. Lungs from rats with pneumonia had significantly longer T2f and T2s values than lungs from rats with radiation pneumonitis and fibrosis. The T2f and T2s values for a "pneumonia lung" were not significantly different from those of muscle. The measured values of T2f and T2s suggested that radiation pneumonitis and fibrosis likely exhibit lower signal intensities than do muscle and that a "pneumonia lung" likely exhibits a similar signal intensity to that of muscle on T2-weighted MR images.

Animals↗
PubMed1993

Centrally driven slow oscillating potential of extrathoracic trachea.

Spontaneous electrical activity of extrathoracic trachea was recorded along with force developed by tracheal smooth muscle and phrenic nerve activity in decerebrated, paralyzed, and artificially ventilated dogs with pneumothorax. The tracheal electrical activity exhibited slow oscillating potentials that were coupled with spontaneous phasic contraction of trachea. Both rhythmic changes were synchronous with central respiratory rhythm represented by phrenic burst, independent of the respirator's rhythm. The dominant component of the slow oscillating potentials consisted of sinusoidal waves with large amplitude that occurred shortly after cessation of phrenic burst, i.e., in the postinspiratory phase. The concomitant small change in the slow oscillating potentials began in the late inspiratory phase just before the initiation of the tracheal contraction. This phase relationship was preserved after removal of intrathoracic vagal afferents from lungs. Such slow oscillating potentials were also observed during lung collapse produced by disconnecting the tube attached to the respirator. Transection of recurrent laryngeal nerves abolished the slow oscillating potentials. These results indicate that the slow oscillating potentials of the extrathoracic trachea are generated by a physiological process associated with the central respiratory rhythm. The dominant component of the slow oscillating potentials occurs in the postinspiratory phase.

Anesthesia↗
PubMed1993

Changes in diaphragmatic EMG activity during sleep in space.

It remains unknown how increased upper airway resistance (UAR) during sleep could be a function of gravity. We therefore conducted quantitative evaluation of the gravitational influence on diaphragmatic EMG activity (EMGdi) in an astronaut to estimate the effect of UAR in space. EMGdi was recorded by paired surface electrodes on the ground (control, C) and abroad a short-term space mission (space, S) for 30 consecutive h. Mean EMGdi recorded during quiet breathing in wakefulness was assigned the value of 100. EMGdi in C was significantly enhanced in all sleep stages compared with that while awake in the supine position (mean +/- SD, 230 +/- 23.2% in non-rapid eye movement (non-REM) Stage II, 233 +/- 13.8 in slow-wave sleep, and 233 +/- 40.0 in REM sleep versus 100 +/- 17.3 in wakefulness, p < 0.001). In contrast, there was no statistical difference in EMGdi in S between awake and any non-REM sleep stage (mean +/- SD, 100 +/- 20.5% in wakefulness versus 103 +/- 16.9 in non-REM Stage II and 100 +/- 14.8 in slow-wave sleep; NS). However, EMGdi in REM sleep in S was statistically greater (132 +/- 28.3%) than that during wakefulness or any other sleep stage in space (p < 0.001). Therefore, gravity may play a much more significant role in the normal healthy human in the increased upper airway resistance during sleep than the relative atonia of the upper airway muscles.

Analysis of Variance↗
PubMed1993

[Successful treatment of diaphragm pacing-induced obstructive sleep apnea syndrome with nasal CPAP].

We report a 71-year-old female patient with primary alveolar hypoventilation syndrome who received diaphragm pacing (DP) and developed obstructive sleep apnea syndrome (OSAS). Application of nCPAP markedly improved her nocturnal hypoxemia. The monitored polygrams before and after the application strongly suggested that the main mechanism of OSAS was an imbalance of activity between upper airway dilator muscles and pump muscles. Moreover, paradoxical movement of the rib cage is not necessarily due to upper airway obstruction. Monitoring of tidal volume and arterial oxygen saturation is essential for the diagnosis of DP-induced OSAS.

Aged↗
PubMed1993

[Proton magnetic resonance spectroscopy (1H-MRS) of peripheral blood lymphocytes in patients with sarcoidosis and interstitial pneumonitis].

We recently developed a method of proton magnetic resonance spectroscopy (1H-MRS) to measure the 1H-MR spectra of peripheral blood lymphocytes (PBL) using only 10(7) cells. We investigated the clinical feasibility of this method for evaluating disease activities in sarcoidosis and interstitial pneumonitis. PBL was separated from 10 ml of venous blood by differential centrifugation with Ficoll-Conray. Using a 90 MHz MR spectrometer (EX90, JEOL), the spectrum was obtained with 4000 times accumulation of 1H signals by single 70 degree pulses at 37 degrees C under spinning. Water signal was suppressed with the homo-gated decoupling sequence. The spectra were analyzed with Gaussian curve fitting. The spectra of patients with active disease showed significant increases in peak heights for (CH2)n and CH3 peaks compared with the control. The peak heights decreased after improvement of disease states. The changes in 1H-MR spectra suggested activation of PBL in patients with sarcoidosis and interstitial pneumonitis, since similar changes have been shown for cells activated with mitogens. Our preliminary results indicate that 1H-MRS may be useful to evaluate activation of PBL in sarcoidosis and interstitial pneumonitis.

Adult↗
PubMed1993

[A case of angiosarcoma presenting as ill-defined opacities on chest roentgenogram and hemothorax].

A 74-year old male was referred to the Tokai University Hospital for evaluation of abnormal opacities on a chest roentgenogram. Laboratory tests demonstrated leukocytosis, elevated ESR and CRP, elevated LDH, and hypoxemia. The chest roentgenogram demonstrated several ill-defined nodular infiltrates on the bilateral upper lung fields. In addition, a CT scan revealed bilateral pleural effusion which was found bloody on diagnostic thoracocentesis. Administration of antibiotics failed to improve lung infiltration or laboratory data. The patient died of respiratory failure on the 23rd hospital day. At autopsy, multiple ill-defined nodules, which were associated with alveolar hemorrhage, were scattered in the lungs bilaterally. Both hematoxylin-eosin and silver staining showed atypical cells of a vasoformative nature. Factor VIII related-antigen in the tumor cells was confirmed by the peroxidase-antiperoxidase method. These findings were consistent with angiosarcoma. The tumor foci were demonstrated in the lungs, pleura, kidneys, bone marrow, adrenal glands, and the gastrointestinal tract. The primary site of angiosarcoma, however, was not identified. Angiosarcoma, either primary or metastatic to the lungs, should be included in the differential diagnosis of multiple ill-defined nodular opacities associated with hemothorax.

Aged↗
PubMed1992

In vivo recording of electrical activity of canine tracheal smooth muscle.

Electrical activity of the tracheal smooth muscle was studied using extracellular bipolar electrodes in 37 decerebrate, paralyzed, and mechanically ventilated dogs. A spontaneous oscillatory potential that consisted of a slow sinusoidal wave of 0.57 +/- 0.13 (SD) Hz mean frequency but lacked a fast spike component was recorded from 15 dogs. Lung collapse accomplished by bilateral pneumothoraxes evoked or augmented the slow potentials that were associated with an increase in tracheal muscle contraction in 26 dogs. This suggests that the inputs from the airway mechanoreceptors reflexly activate the tracheal smooth muscle cells. Bilateral vagal transection abolished both the spontaneous and the reflexly evoked slow waves and provided relaxation of the tracheal smooth muscle. Electrical stimulation of the distal nerve with a train pulse (0.5 ms, 1-30 Hz) evoked slow-wave oscillatory potentials accompanied by a contraction of the tracheal smooth muscle in all the experimental animals. Our observations in this in vivo study confirm that the electrical activity of tracheal smooth muscle consists of slow oscillatory potentials and that tracheal contraction is at least partly coupled to the slow-wave activity of the smooth muscle.

Action Potentials↗
PubMed1992

31P-NMR study of skeletal muscle metabolism in patients with chronic respiratory impairment.

To evaluate the energy metabolism of peripheral skeletal muscle during exercise in patients with chronic respiratory impairment, the 31P-nuclear magnetic resonance (NMR) spectra of forearm muscle were investigated in nine patients and nine age-matched control subjects. We calculated the phosphocreatine (PCr) to PCr + inorganic phosphate (PI) ratio, the time constant of PCr recovery and the intracellular pH. The exercise consisted of repetitive hand grips against a 2-kg load every 3 s for 6 min (0.33 W). The patients showed a marked decrease in the PCr/(PCr + PI) ratio and pH in the muscle during exercise in contrast to the control subjects whose PCr/(PCr + PI) showed a minor decrease without any change in pH. The relationship between PCr utilization and pH demonstrated that anaerobic glycolysis switched on earlier in patients with chronic respiratory impairment. A split PI peak was observed in five of nine patients during exercise. The PCr/(PCr + PI) ratio during the last minute of exercise correlated significantly with the vital capacity (% predicted), with the FEV1/FVC, with the body weight, with the maximum strength of hand grip, and with the muscle mass. The results indicate impaired oxidative phosphorylation and the early activation of anaerobic glycolysis in the muscles of patients with chronic respiratory impairment. Several factors related to chronic respiratory impairment, such as disuse, malnutrition and dysoxia, would contribute to the metabolic changes observed in the muscles examined.

Aged↗
PubMed1992

Reperfusion after a two-hour period of pulmonary artery occlusion causes pulmonary necrosis.

The role of reperfusion injury in the progression to necrosis in pulmonary embolism was evaluated. To simulate this condition, we used a technique that enables occlusion and reopening of the pulmonary arterial branch supplying the right upper lobe in conscious rats. The rats were divided into five groups: the occlusion group (n = 12), in which the pulmonary artery (PA) branch was occluded without reperfusion; the reperfusion group (n = 12), in which the PA branch was reopened after a 2-h period of occlusion; and the reperfusion-SOD (n = 9), reperfusion-IM (n = 8), or reperfusion-IA-SOD (n = 6) groups, in which superoxide dismutase (SOD), indomethacin (IM), or inactivated SOD (IA-SOD), respectively, was administered during reperfusion. The lungs were removed 24 h after the PA occlusion, and histologic examination was performed. In the occlusion group, the alveolar structure of the right upper lobe was well preserved, and there was no erythrocyte or leukocyte accumulation. The only significant changes compared with the control lobe was the appearance of wavy internal elastic lamina of the PA and slight neutrophil adherence to the endothelial cells. In contrast, the right upper lobe of the reperfusion group disclosed numerous foci of hemorrhagic necrosis, with disrupted alveoli and leukocyte accumulation in all cases. With SOD treatment, the changes compatible with hemorrhagic necrosis were attenuated to the level of the control lobes. However, neither IM nor IA-SOD decreased these changes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Expiratory activity of the inspiratory muscles during cough.

To investigate the neural mechanism of the expiratory activity of the inspiratory muscles during a cough, EMG of the respiratory muscles were recorded in anesthetized and tracheostomized dogs. A laparoscope was used to minimize injury to the abdominal muscles for implantation of the electrodes into the costal diaphragm. During the expulsive phase of a cough, the diaphragm was active in 7 of 12 dogs and the external intercostal muscle was active in 3 of 6 dogs. During a cough, the expiratory activity of the diaphragm, after the termination of its inspiratory activity, started at 52.9 +/- 24.6 ms, and that of external intercostal muscle started at 51.1 +/- 20.5 ms. The expiratory activity of the internal intercostal muscle and of the transversus abdominis started at 34.3 +/- 13.0 and 27.8 +/- 15.2 ms, respectively. The onset of expiratory activity of the inspiratory muscles is significantly later than that of expiratory muscles. Continuous activity in the expiratory muscles evoked by airway occlusion, i.e., Hering-Breuer reflex, was suppressed during the inspiratory phase of a cough, but not suppressed during the expulsive phase even when the expiratory activity of the diaphragm was observed. We concluded that the expiratory activity of inspiratory muscles is controlled independently of both expiratory activity of the expiratory muscles and inspiratory activity of the inspiratory muscles.

Animals↗