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Biomedical subjects

H Yamabayashi

Publications and source records attributed to H Yamabayashi.

At least 37 records · Page 2Linked to original sources
PubMed1992

[A case of mediastinal teratoma--differentiation from lung abscess and bronchogenic carcinoma].

A 38-year-old man was admitted with persistent productive cough and right anterior chest pain. Chest X-ray showed two large masses connected with each other, one in the right lung field and the other in the anterior mediastinum. A tentative diagnosis of either lung abscess or bronchogenic carcinoma was initially made, because of elevated serum tumor markers (SLX and SCC) and persisting refractory inflammatory sings. However, open chest drainage revealed a few fine hairs and atheromatous materials within the masses, and the diagnosis of teratoma was made. We removed these masses, and investigated the reason for the elevation of tumor markers. Staining with SLX monoclonal antibody demonstrated that the pancreatic tissue in the masses contained SLX. Although this is the first reported case of teratoma producing tumor marker (SLX), it is highly possible that tumor markers may be elevated in the majority of patients with teratoma because of the genesis of this tumor.

Adult↗
PubMed1992

[Activity of the respiratory muscles during natural defecation: a study on experimental animals].

Activity of the respiratory muscles during natural defecation was studied in two anesthetized and two decerebrate dogs. In anesthetized dogs, excitation of the abdominal muscles and an increase in gastric pressure were observed during defecation. However, pleural pressure was little influenced by such increase in abdominal pressure, maintaining the same rhythmic changes as observed during spontaneous respiration. The rhythmic changes in pleural pressure were associated with rhythmic activity of the diaphragm. When gastric pressure increased during defecation, the diaphragmatic activity also increased during both the inspiratory and expiratory phases. In a decerebrate dog, airflow and airway pressure changed similarly to during defecation. The diaphragm was continuously active, with superimposed rhythmic augmentation. In a paralyzed and artificially ventilated dog with open-chest, the phrenic nerve similarly developed discharges. We conclude that the non-respiratory activity and rhythmic augmentation of phrenic nerve discharge during defecation is pre-programmed in the command for defecation. The activity of phrenic motoneurons may be further modulated by changes in thoracic and abdominal pressure. These mechanisms may act together to coordinate respiration and defecation.

Anesthesia↗
PubMed1991

Influence of central respiratory activity on the cough response in anesthetized dogs.

Cough responses evoked by mechanical stimulation of the tracheobronchial mucosa in anesthetized and tracheostomized dogs were studied. The most common response was a group of coughs. Phase relationships between coughing and spontaneous respiration during the cough initiation and resolution periods were categorized as either synchronized or unsynchronized. We defined the synchronization as the coincidence of an expiratory thrust and the early-expiratory phase of respiration. During the cough initiation period, the incidence of synchronization increased as central respiratory activity was enhanced by hypercapnia or as the cough center's activity was suppressed by deep anesthesia. Synchronization decreased as central expiratory activity was enhanced by expiratory threshold loading. During the cough resolution period, synchronization occurred in conjunction with a gradual decrease in the cough center's activity. Coughing could be evoked when the dog was made apneic either by hyperventilation or by the Hering-Breuer reflex. In either case, apnea persisted after coughing subsided. These findings suggest that mechanical stimulation directly activates the cough center rather than the respiratory center; and that synchronization is determined by the relative strengths of the respiratory and cough center's activities.

Afferent Pathways↗
PubMed1990

A 1-year time course study of the relaxation times and histology for irradiated rat lungs.

To investigate the NMR relaxation times for irradiated rat lung tissue, we measured T1 and T2 at 11 different times during the injury's 1-year time course. A biexponential analysis of T2 was used to determine T2 fast (T2f) and T2 slow (T2s). In addition, we measured water content and correlated changes in the relaxation times with pathological changes. The correlation indicates the following: (1) Shortly after irradiation, the biexponential T2 decay for 1/3 of the samples became monoexponential and there were no noticeable pathological changes observed using light microscopy. (2) During radiation pneumonitis, T2f and T2s were prolonged. This accompanied acute edematous changes and inflammatory cell infiltration. (3) Finally, during radiation fibrosis T1 shortened and collagen increased. We observed no significant correlation between relaxation time changes and water content changes throughout the 1-year time course.

Animals↗
PubMed1990

T2 of endotoxin lung injury with and without methylprednisolone treatment.

NMR relaxation times (T1 and T2) and the water content (WC) of in vitro rat lungs were measured during the course of endotoxin lung injury in rats. Measurements of normal lungs, untreated endotoxin-injured lungs, and endotoxin-injured lungs treated with methylprednisolone (MPSL) were compared. The untreated endotoxin lungs showed prolongation of the fast and slow T2 components (T2f and T2s), but no significant changes in T1 or water content. Also, there was no correlation between 1/WC and relaxation rates or between T1 and T2. MPSL treatment prevented T2f and T2s prolongation; however, the duration of MPSL effectiveness was limited. Animals which were treated with MPSL more than 7 h prior to measurements showed T2 prolongation. This study indicates that NMR relaxation times, particularly T2, can be useful in evaluating lung injuries and their treatments.

Animals↗
PubMed1990

Acute respiratory failure in multiple sclerosis.

A 23-year-old woman developed acute respiratory failure in the course of multiple sclerosis. The lack of bulbar dysfunction, the presence of quadriplegia, and the bilateral diaphragmatic weakness indicated the presence of spinal cord lesions involving pyramidal tracts bilaterally. Magnetic resonance imaging revealed a cervical demyelinating lesion between C1 and C3.

Acute Disease↗
PubMed1990

Transient neuromuscular impairment resulting from prolonged inhalation of halothane and enflurane.

Inhalation anesthesia first with halothane followed by enflurane relieved a patient with status asthmaticus who was refractory to conventional therapy including mechanical ventilation. After 13 days of anesthesia while on mechanical ventilation and employing nondepolarizing muscle relaxants, significant neuromuscular impairment, manifested by tetraplegia and sensory disturbance, developed. Anesthesia was discontinued on day 14, and the patient was weaned from mechanical ventilation on day 16. Over the next two months, the neuromuscular impairment markedly improved. Halothane was associated with cardiac arrhythmias and hepatitis necessitating replacement by enflurane. Enflurane appeared to be as effective a treatment for refractory asthma as halothane. The most probable cause of the neuromuscular impairment in our patient was the long-term use of inhalation anesthetics or nondepolarizing muscle relaxants.

Adult↗
PubMed1990

Continuous positive airway pressure breathing in supine and upright postures.

Continuous positive airway pressure (CPAP) breathing of 10 cmH2O was applied to 10 healthy conscious subjects both in supine and 70 degree head-up postures. CPAP increased the end-expiratory lung volume from 2.44 +/- 0.66 (S.D.) to 3.07 +/- 0.68 liters in supine subjects, and from 3.01 +/- 0.57 to 3.64 +/- 0.57 liters in head-up subjects. During CPAP, rib cage motion became predominant when compared to abdominal motion in upright posture. Among the respiratory parameters, inspiratory duration was significantly shortened during CPAP in either posture, but was changed less significantly by individual posture change alone. Mean inspiratory flow decreased during CPAP only in upright posture. Abdominal muscles were recruited for expiration during CPAP in either posture, and the EMG recorded from the lower intercostal space developed inspiratory activity during CPAP in head-up posture. All of 10 subjects felt most dyspneic during CPAP with the head-up. We conclude that the mechanism of increase in lung volume during CPAP is mediated by different pathway from that of posture change, and that CPAP in upright posture can alter the respiratory pattern of the subject.

Adult↗
PubMed1990

[Control mechanism of the respiratory muscle during forced expiration].

Control mechanism of the respiratory muscle during forced expiration was analyzed. Respiratory flow. EMG of the intercostal muscle (IC), external oblique (EO) and internal oblique (IO) abdominal muscle were analyzed in eleven healthy volunteers. The pattern of EMG activity during forced expiration could be classified according to its shape i.e., taper- or hill-shaped. The taper shape was found in 7 of 9 subjects for IC and in 8 of 11 subjects for EO. The hill shape was found in 4 of 6 subjects for 10. Twelve consecutive trials without intervals did not alter the pattern of flow-volume curve, activity of respiratory muscle and frequency component (i.e., H/L ratio). When the expiratory circuit was obstructed for a short interval during forced expiration, the rise in pleural pressure was slight but that in oral pressure was large, and the activity of respiratory muscle decreased for a short period. The latencies from the onset of expiratory circuit obstruction to the reduction in EMG activity were 61.5-100 msec. In IC, 61.5-106.5 msec in EO. and 58.0-92.3 msec in 10. These values did not differ significantly any given subject. Airway anesthesia with xylocaine did not alter latency. In conclusion, the pattern of respiratory muscle activity for forced expiration is predetermined and is specific for each muscle. Negative feedback from receptors in airway or in respiratory muscle was strongly suggested. Repetitive trials up to twenty times did not cause respiratory muscle fatigue.

Adult↗
PubMed1990

[A case report of diaphragmatic flutter].

A 18-year-old female complained of a dyspneic sensation and involuntary movements in the epigastrium. On physical examination, fine rhythmic movements in the epigastrium were observed on each inspiration with a rate of 5-10 per breath. Arterial blood gas analysis was normal. Recording of the respiratory parameters and the EMG of respiratory muscles were performed. Analysis of the respiratory flow revealed that her spontaneous inspirations consisted of short inspirations (i.e., flutter wave) (150-170 beats per minute). EMG of respiratory muscles demonstrated that these flutter waves were driven by intercostal muscles and diaphragm. The flutter waves were not suppressed by breath holding at the maximal inspiration. With intravenous injection of 200 mg of diphenylhydantoin, flutter waves disappeared within 10 minutes. There were no abnormal findings on chest roentgenogram, electrocardiogram, head CT scan and MRI of the cervical spine. During one year's follow up no attack developed again. We have encountered 3 cases of the syndrome since 1981. In two of them, the spontaneous respiration was superimposed on a high-frequency wave throughout the whole respiratory cycle while in one case the high-frequency wave developed only in the inspiratory phase of spontaneous respiration. In the present case the respiratory flow pattern was similar to the last mentioned and the EMG-analysis of respiratory muscles confirmed that the flutter waves were driven by intercostal muscles and diaphragm. Furthermore, synchronization of activities of the two respiratory muscles suggests that the syndrome is of central origin.

Adolescent↗
PubMed1989

Effect of cold pressor test on carbon monoxide diffusing capacity in normal subjects.

We investigated changes in the pulmonary carbon monoxide diffusing capacity (DLco) during the cold pressor test (CPT) on 25 normal subjects. In 10 of them we also observed changes in circulatory parameters by a computerized dual cadmium telluride detector system, using an equilibrium radionuclide blood-pool label. DLco and DLco per unit of alveolar volume (DLco/VA) averaged in the control period were 29.4 +/- 4.1 ml/min/mm Hg, 6.1 +/- 0.8 ml/min/mm Hg/l (mean +/- SD). During the 2nd minute of CPT, DLco increased by 3.6 +/- 1.5% and DLco/VA by 5.1 +/- 1.5% (mean +/- SE). The systemic blood pressure increased by 17% (mean increase) whereas the heart rate and the stroke volume remained unchanged. The increases were small but significant (p less than 0.05, p less than 0.01, respectively). We conclude that the increase in DLco is due to cold-induced systemic vasoconstriction followed by a passive shift of blood into the pulmonary vasculature.

Adult↗
PubMed1989

Role of the mediastinum as a part of the chest wall: analyzed by computed tomography.

Using computed tomography (CT), geometrical changes in pulmonary structures in 4 human volunteers were analyzed. A series of parallel transaxial CT scans of the lung were obtained for each volunteer while he held his breath at maximal inspiration and maximal expiration. Changes in pulmonary structures were evaluated by comparing the maximal inspiration scans for each slice position. The longitudinal displacement of the lung volume was categorized as either a rib cage displacement or a diaphragm-abdominal displacement. The ratio of diaphragm-abdominal contribution to vital capacity was 0.49-0.65 for the volunteers. The thoracic volume displacement was categorized as either a mediastinal displacement or a rib cage displacement. The former was considerably larger than the latter. Since the rostral end of the mediastinum is fixed to the thoracic cage and the caudal end is fixed to the diaphragm, we conclude that the mediastinum-diaphragm boundary converts the axial force generated by the diaphragmatic excursion into radial force.

Adult↗
PubMed1989

Dual-respiratory rhythms. A key to diagnosis of diaphragmatic flutter in patients with HVS.

We discuss three cases of diaphragmatic flutter in patients with extreme polypnea and symptoms of respiratory alkalosis. Initially, the diagnosis for each case was HVS. However, analysis of the respiratory pattern during attacks revealed two frequencies. A fast respiratory rhythm (230 to 250 breaths per minute) was superimposed on a slow rhythm (15 to 30 breaths per minute). The fast rhythm maintained blood gases at normal limits or hypocapnic levels. The dual respiratory rhythms, which do not occur with HVS, indicated diaphragmatic flutter. In addition, the usual treatment for HVS-breathing CO2 mixed air-did not influence the attacks. For two of the three patients, an intravenous dose of DPH suppressed the abnormal respiratory patterns immediately and completely. The third patient responded to an intramuscular injection of haloperidol. For these cases, the dual respiratory rhythms were the key to diagnosis of diaphragmatic flutter which accompanied hyperventilation.

Adolescent↗
PubMed1989

A computerized standard flow-generator for spirometer calibration.

We analyzed the dynamic characteristics of a newly designed standard flow generator (SFG) to be used for spirometer calibration. The SFG consisted of a computer, large-bore cylinder, and piston driven by a high torque motor. The computer develops numerical equations to simulate a flow-volume pattern with different convexities of the descending limb. The excursion of the piston was processed according to the computer-developed equation. The computer's numerical solutions were compared to those of the SFG and agreement of the values of the peak flow, forced expiratory volume, and flow-volume pattern was satisfactory in repeated trials. Application of an external resistive load (3.5 cm H2O/sec) did not change the flow output. However, there were several minor disagreements due to the dynamic characteristics of the SFG. In an emphysema pattern the ascending limb of the generated flow-volume curve flattened and the descending limb was less convex compared to the preset pattern. When the SFG was generating sinusoidal waves of high frequency (e.g., 10.0 Hz) the flow output was deformed. The newly designed SFG was used to examine the dynamic characteristics of rolling-seal spirometers. There was an overshoot of the peak flow, over-convection, and oscillations of the descending limb in the spirometer output. These deformations were more prominent with the severe emphysema pattern. It is concluded that the SFG can be very useful in the examination and calibration of spirometers.

Computers↗
PubMed1988

Acute and repair stage characteristics of magnetic resonance relaxation times in oxygen-induced pulmonary edema.

Proton magnetic relaxation times, T1 and T2, were determined for rat lungs exposed to 80% oxygen for a duration of 2 weeks. The transverse magnetization decay curve of the lung tissue was multiexponential. A linear combination of two decay curves with different T2 values fits the multiexponential decay suggesting that there are at least two different components of tissue water in the lung. Remarkable prolongation of T1 and T2 was demonstrated as lung injuries progressed in the acute stage of pulmonary edema. Both 1/T1 and 1/T2 were significantly correlated with 1/water content of the lung tissue. In the repair stage, T1 and T2 were significantly shortened. Shortening coincided with the spontaneous resolution of pulmonary edema. Relaxation rates showed no significant correlation with 1/water content in this stage. These results indicate that the physical state of water in the tissue is affected not only by the water content but also by the derangement of macromolecules in pulmonary edema. T2 was more sensitive than T1 for detecting pulmonary damage.

Animals↗
PubMed1988

Lung cancer: differentiation of tumor, necrosis, and atelectasis by means of T1 and T2 values measured in vitro.

In vitro measurements of T1 and T2 values were performed in surgical specimens from 15 patients with lung cancer. Correlation between histologic results and measured values revealed that different pathologic tissues can be characterized by means of T1 and T2 values. The transverse magnetization decay curve of the lung tissue was multiexponential, which can be explained by two different relaxation times, fast T2 and slow T2. The signal intensity of pathologic lung tissues at different pulse sequences was simulated on a signal intensity gradient graph based on measured values of T1, fast T2, slow T2, and water content. The results showed that T2-weighted sequences were more valuable in discriminating viable lung cancer from necrotic tumor and collapsed lung lesions.

Carcinoma, Squamous Cell↗
PubMed1988

Kinetics of mixed venous oxygen tension during rhythmic contraction of the hindlimb of dogs.

Change in mixed venous oxygen tension (PVO2) during transition from rest to exercise induced by rhythmic contractions of the hindlimb of dogs was continuously monitored using intravascular oxygen electrodes. The rapid fall in PVO2, on the average 9.5 sec after the onset of rhythmic contraction, was found. The time course of change in PVO2 was not altered by ligation of the splenic artery and vein. Oxygen tension of venous blood in the superior vena cava and the inferior vena cava was monitored in order to elucidate the mechanism of rapid fall in PVO2 following induced exercise. Oxygen tension of venous blood in the superior vena cava did not fall at the onset of contraction. Oxygen tension of venous blood in the distal and proximal end of the inferior vena cava began to fall at 4.4 sec and at 6.9 sec after the onset of contraction on the average, respectively. There was no significant difference between the hematocrit of mixed venous blood at rest and after 15 sec of exercise. These findings suggest that the rapid fall of PVO2 results from a surge of low oxygenated blood from the exercising hindlimb and that this change in blood gas tensions possibly reaches the lung within 10 sec after the onset of exercise.

Animals↗