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Biomedical subjects

S Yagi

Publications and source records attributed to S Yagi.

At least 199 records · Page 11Linked to original sources
PubMed1991

Time-varying myocardial elastance of canine left ventricle.

A formula was derived from an active cross-bridge model for expressing the "time-varying myocardial elastance" of the left ventricular (LV) wall. To assess the validity of this model's predictions of the behavior of the intact left ventricle, eight healthy beagles were instrumented with ultrasonic crystals to measure LV diameter and a micromanometer for LV pressure measurement. During ejecting beats starting from short end-diastolic myocardial lengths, the predicted values for myocardial elastance and force closely approximated the measured values for the instantaneous external load-muscle length ratio and the external load, respectively. However, in cycles starting from long end-diastolic lengths, the predicted myocardial elastance and force values deviated from the actual values during the shortening phase of LV contraction. The differences between myocardial elastance and external load-muscle length ratio as well as those between force and external load during the shortening phase (shortening deactivation) appeared to result from an internal load in the shortening myocardium that was closely related to the product of instantaneous myocardial force and shortening velocity. Thus this model may provide reasonable approximations of myocardial elastance and force in the intact LV wall. In addition, time-varying myocardial elastance might reflect time-dependent changes in calcium activation.

Animals↗
PubMed1991

Altered phospholipase C activity in renal medulla of DOCA-salt hypertensive rats.

We investigated the alterations of phospholipase C activity in the kidney and arterial wall of deoxycorticosterone acetate (DOCA)-salt hypertensive rats. Neither DOCA nor salt administration alone affected phospholipase C activity in the kidney and arterial wall. In contrast, when the rats were given both DOCA and salt and developed high blood pressure, the phospholipase C activity became greater in the outer and inner medulla (papilla) while the enzyme activity was reduced significantly in the renal cortex and arterial wall. Such an increase in phospholipase C activity was not observed in the kidney of a genetic rat for spontaneous hypertension. Moreover, the phospholipase A2 activity was also stimulated in the renal medulla of DOCA-salt hypertensive rats. Thus, these data indicate that DOCA-salt hypertension is associated with an increase in phospholipase C activity in the renal medulla, which seems primary to the development of DOCA-salt hypertension.

Animals↗
PubMed1991

Cross-bridge cycling energy of cardiac muscle estimated from an active cross-bridge model.

A mathematical formula was derived from an active cross-bridge model to express the changes in the active myocardial force which occurred during systole. Using the formula and the assumption that the energy expenditure for cross-bridge cycling (Um) was a linear function of the force-time integral (FTI), we developed formulae describing the left ventricular Um versus FTI relation, the Um versus force relation, and the Um versus pressure-volume area (PVA) relation. There were strong disagreements between the model predictions and the experimental findings relating oxygen consumption of the heart versus the PVA relation. These differences may have resulted from the oversimplification of important mechanical and/or biochemical properties of the myocardium in the model. However, the model appeared to accurately reproduce the Fenn effect (effect of contraction modes on energy liberation) for the myocardium as well as the effect of catecholamine infusion, hypothermia, and hypothyroidism on the changes in the binding rate of Ca2+ with the regulatory proteins, the myosin ATPase activity, the peak force developed, and the myocardial energy expenditure. We present this work as an intermediate step towards a complete theoretical linkage between the molecular biology, dynamics, and energetics of the human heart.

Biomechanical Phenomena↗
PubMed1991

Afterloading increases the left ventricular end-systolic force-length relation slope in dogs.

We evaluated the effects of pressure loading produced by gradual aortic occlusion on left ventricular (LV) myocardial contractility by assessing changes in the slope of the LV end-systolic force-diameter (Fes-Des) relation. Eleven adult mongrel dogs were prepared with ultrasonic crystals for measuring LV diameter and a micromanometer for measuring LV pressure. Preload was decreased by vena caval occlusion (VCO), and afterload was increased by aortic occlusion (AOO). The slopes (Ec) and extrapolated diameter intercepts (Do) of the LV Fes-Des relation were determined for each dog from the end-systolic data obtained during VCO and AOO. During VCO and also AOO, the heart rate showed little change (134 +/- 18 vs. 134 +/- 16 bpm in VCO, 135 +/- 16 vs. 132 +/- 17 bpm in AOO). The values of Ec and Do during VCO were 62.8 +/- 15.6 g/cm and 1.20 +/- 0.36 cm, respectively, while during AOO the respective values were 122.6 +/- 18.6 g/cm and 1.66 +/- 0.38 cm. Ec and Do were both significantly increased during AOO in comparison with VCO (p less than 0.001). These results suggest that gradual aortic occlusion increases LV myocardial contractility in anesthetized, open-chest dogs under autonomic blockade. This phenomenon might be related to length-dependent calcium activation.

Animals↗
PubMed1991

[A case of eosinophilic granuloma of the cervical lymph nodes associated with pulmonary cystic lesions].

A 33-year-old man was referred to our department because of left cervical lymphadenopathy for one month which did not respond to antibiotics. Histological examination of the lymph node biopsy revealed eosinophilic granuloma. However, repeated bronchoscopic examinations performed to evaluate the pulmonary lesions appearing on chest roentgenograms and chest CT scans revealed no evidence of eosinophilic granuloma. Steroid therapy resulted in resolution of the cervical lymphadenopathy, but the pulmonary lesions showed no response. The possible relationship between eosinophilic granuloma and pulmonary cystic lesions in our patient is discussed.

Adult↗
PubMed1991

[A successful report of emergency CABG for severe calcified thoracic aorta--the porcelain aorta].

The best management for patients requiring CABG with severe calcification of the thoracic aorta has not be established. To clamp ascending aorta in such cases produce cerebral embolization, aortic dissection or mural laceration. We reported a 60-year-old male for unstable angina with LMT lesion. Emergency CABG using IABP was performed with femoral cannulation, moderate hypothermia and induced ventricular fibrillation. His postoperative course was uneventful and coronary arteriography revealed a satisfactory patent graft of the RITA to the LAD system.

Aorta, Thoracic↗
PubMed1991

[The renal nerve and cardiovascular responses to renal receptor stimulation with veratrine in dogs].

Renal nerve and cardiovascular effects of intrarenal veratrine (Ver) were investigated using the cross-perfused kidney preparations of anesthetized dogs. Ver (1 and 3 micrograms/kg), injected as a bolus, elicited increases in arterial blood pressure (ABP), heart rate (HR) and renal efferent nerve activity (RENA). Ganglion blockade, hexametonium (2 mg/kg) markedly diminished increases in ABP, HR and RENA induced by Ver. In a separate group of animals, significant increases in renal afferent nerve activity (RANA) occurred after Ver administration. It is concluded that selective intrarenal Ver activates renal nerve afferents, and these results in cardiovascular changes are consistent with efferent sympathetic activation.

Animals↗
PubMed1991

[Ischemic heart disease detected by the standard deviation of the spatial QRS-T angle and by treadmill exercise test].

Beat-to-beat fluctuations of the spatial QRS-T angle, which are reported to be greater in patients with ischemic heart disease than in healthy subjects, are thought to be a helpful factor in diagnosing ischemic heart disease. In this study, we assessed the usefulness of the standard deviation of the spatial QRS-T angle per beat as an index of magnitude of the fluctuations. The subjects consisted of 27 patients with effort angina, 14 with vasospastic angina, 18 with the "chest pain syndrome" and 36 normal controls. The standard deviations of the spatial QRS-T angle were obtained for 10 consecutive stable beats at rest using Frank's orthogonal X, Y, Z scalar electrocardiogram. The results were compared with those of coronary angiography and exercise tolerance tests. Treadmill exercise tests were performed in all patients using Bruce's protocol to observe decreased ST levels and delta ST/HR indices. QRS-T angle deviation values were 8.10 +/- 8.64 degrees (mean +/- SD) in the effort angina group, 3.63 +/- 1.26 degrees in the vasospastic angina group, 4.13 +/- 1.70 degrees in the "chest pain syndrome" group, and 2.35 +/- 0.85 degrees in the normal control group; the groups of patients with heart disease showed significantly higher values (all p < 0.01) than did the control group. The effort angina group showed a significantly higher value than did the vasospastic angina group and the "chest pain syndrome" group (all p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Angiography↗
PubMed1991

[Successful report of total aortic root replacement by a new technique].

We employed a new procedure of the total aortic replacement in 2 cases which is made of composite graft and reimplantation of the coronary arteries by direct suture technique. These patients took good clinical course and were discharged after operation. We believe that this procedure is a very useful for annuloaortic ectasia or dissecting aortic aneurysm involved coronary artery with aortic regurgitation.

Aged↗
PubMed1991

[A case of oral gold tablet-induced interstitial pneumonitis].

A 76-year-old woman was admitted with exertional dyspnea and chest roentgenographical abnormal shadows appearing after oral gold therapy (total 720 mg) for rheumatoid arthritis. Based on the patient's clinical course, chest roentgenograms, chest CT and pathological findings of TBLB specimens, gold pneumonitis was diagnosed. Steroid therapy improved symptoms and pulmonary function and cotton-like shadows on chest roentgenograms and chest CT scanning. However, linear and large ringed shadows on chest roentgenograms and chest CT scan remained, even after steroid therapy. This case is the first case of oral gold tablet-induced pneumonitis. Although the mechanism of oral gold tablet-induced pneumonitis is considered to be almost the same that of gold injection therapy-induced pneumonitis, this case suggested that fibrotic changes in oral gold tablet-induced pneumonitis may be delayed over a long period.

Administration, Oral↗
PubMed1990

Organization and structure of the 5' flanking region of the rat serine dehydratase gene.

For study of the mechanisms regulating the induction of serine dehydratase by various hormones in rat liver [Noda et al. (1988) J. Biol. Chem. 263, 14764-14768], we cloned the gene for this enzyme from a rat genomic library. The gene spans about 7.5 kilobases and consists of nine exons and eight introns. The exon-intron boundaries are consistent with the "GT-AG" rule. Southern blot analysis of rat genomic DNA suggested the presence of one copy of serine dehydratase gene per haploid genome. The 5' end of serine dehydratase mRNA is located 148 nucleotides upstream of the initiator methionine codon. ATG, determined by primer extension analysis and S1 nuclease mapping, although an alternative transcription initiation site(s) may be located a few bases downstream. The 5' flanking region of the gene lacks typical TATA and CCAAT sequences, but contains AATAAA and CATT sequences, at -25 to -20 and -54 to -51, respectively. Furthermore, there are five GC box-related sequences. There are three putative glucocorticoid-responsive elements and two copies of the CGTCA motif of the cAMP-responsive element upstream of the promoters. The 5' flanking sequence shows more than 98% homology with that reported by Ogawa et al. [(1988) Proc. Natl. Acad. Sci. U.S.A. 85, 5809-5813], but the first exons have different sequences. Another difference is that a segment of 108 nucleotides is located just upstream of exon 5 in the sequence reported here, but is included as an exon in the sequence of Ogawa et al. The possibility to producing two species of serine dehydratase mRNAs from a single gene by transcription from different sites and alternative splicing is discussed.

Animals↗
PubMed1990

[A case of pneumonia caused by Chlamydia pneumoniae, strain TWAR].

A case of pneumonia caused by C. pneumoniae, strain TWAR is described in this paper. A 65 year-old male with a persistent dry cough was admitted to our division for left lower lobe infiltrates of the chest X-ray. The serum antibody titers against mycoplasma and some viruses were not elevated, but the serum antibody titers against TWAR reached the maximum level (IgG X 1024, IgA X 256) using microplate immunofluorescence antibody technique (MFA). Isolation of TWAR was tried by BAL and nasophalingial swabs, but were not successful. TBLB from Lt. S10 revealed TWAR inclusion bodies within alveolar epithelial cells using TWAR specific monoclonal antibody (Washington Research Foundation).

Aged↗
PubMed1990

Approximation of various canine left ventricular end-systolic relations by a cylinder model.

Assuming a linear end-systolic force-length relation and a cylindrical geometry of the left ventricle (LV), we have developed a mathematical model (cylinder model) and derived formulas for LV end-systolic force-diameter (Fes-Des), stress-diameter (Ses-Des), pressure-diameter (Pes-Des), and pressure-cylinder volume (Pes-Ves) relations. To assess the validity of this model for the study of the intact LV, eight healthy beagles were instrumented with ultrasonic crystals to measure LV diameter and wall thickness and a micromanometer to measure LV pressures. Preload was altered by vena caval occlusion. Contractility was increased by addition of Ca2+. Fes-Des relation was nearly linear under control contractility, whereas after addition of Ca2+ this relation became concave toward the diameter axis. Linear approximation was more accurate for this relation than for the Pes-Des and Pes-Ves relations in control contractility. Predictions from the model formulas more accurately reproduced observed data in the Pes-Des (P less than 0.01) and Pes-Ves (P less than 0.001) relations than those from linear regression equations, whereas the model predictions for the Ses-Des relation were as accurate as those of a linear regression equation. Although the slope of the Fes-Des relation increased with inotropic stimulation, diameter intercepts of this relation did not change. Thus the present results obtained under control contractility were consistent with assumptions of the model. This cylinder model might provide reasonable approximations for various canine LV end-systolic relations.

Animals↗
PubMed1990

Effects of insulin on vasoconstrictor responses to alpha agonist and tilting.

The effects of insulin on vasoconstrictor response were studied in diabetics without autonomic neuropathy. Vasoconstrictor response to phenylephrine was measured before and after insulin injection in 10 diabetics. Mean blood pressure, forearm blood flow, and forearm vascular resistance remained unchanged after insulin administration. But the increase in forearm vascular resistance to phenylephrine decreased significantly and heart rate increased significantly after insulin injection. In 9 diabetics, vasoconstrictor response to tilting was measured before and after insulin injection. Mean blood pressure, cardiac index, and the total peripheral resistance index remained unchanged after insulin administration. However, the increase in the total peripheral resistance index to tilting decreased significantly and heart rate increased significantly after insulin injection. Furthermore, a significant fall in mean blood pressure following tilting was observed only after insulin administration. Although blood glucose levels decreased significantly, no hypoglycemic symptoms occurred. The present study suggests that insulin inhibits vasoconstrictor responses to both alpha agonist and tilting in diabetics.

Adrenergic alpha-Agonists↗
PubMed1990

[A case of intrapulmonary schwannoma that should be distinguished from lung cancer].

A 32-year-old woman was referred to our division because of abnormal shadow on a chest X-ray film taken at an annual health survey. Chest X-ray films and chest CT scanning revealed a smooth-surface mass at the left hilus. A bronchoscopic examination revealed severe extraluminal compression in the left basal bronchus but no visible tumors. Surgical treatment was performed on the suspicion of lung cancer. Since the intraoperative frozen section examination revealed a benign tumor, the tumor mass was resected. Based on intraoperative and pathological findings, benign intrapulmonary schwannoma associated with the left basal bronchus was diagnosed. Only 15 cases of intrapulmonary schwannoma have been reported in Japan.

Adult↗
PubMed1990

[Clinical evaluation of pleural effusion--carcinoembryonic antigen (CEA) and adenosine deaminase (ADA) activities in pleural fluids].

We reviewed 327 patients with pleural effusion who had been examined at our department for identification of its cause during the 14 years between 1974 and 1987, and studied the percentages of definitive diagnosis by examining the pleural fluids of patients with malignant tumor and tuberculosis. We also measured the levels of carcinoembryonic antigen (CEA) and adenosine deaminase (ADA) in the pleural fluids of these patients and evaluated their diagnostic usefulness. We further carried out a detailed clinical study of the factors affecting the CEA and ADA activities in the pleural fluids, which are considered to be particularly important in differential diagnosis of patients with pleural effusion. Of 327 patients with pleural effusion, malignancy-related pleurisy was observed in 166 patients (50.8%), and tuberculous pleurisy in 85 (26.0%). The rate of definitive diagnosis based on the examination of the pleural effusion in these patients indicated that 20-30% of them pose difficulty in clinical diagnosis. CEA was positive in 64.7% of patients with malignancy-related pleurisy, and ADA was positive in 97.7% of those with tuberculous pleurisy. These suggested their usefulness as supportive diagnostic methods of those diseases. In addition, CEA was elevated in patients with complications such as empyema, suggesting an effect of non-specific cross-reacting antigen (NCA). ADA showed high values in patients with conditions related to cell-mediated immunological responses as well as empyema and hemolysis. It suggested the release of ADA from blood cells due to hemolysis. These factors must be carefully evaluated in the interpretation of the CEA and ADA activities in pleural effusion.

Adenosine Deaminase↗
PubMed1990

[A case of atonic partial seizure].

This report presented a 4-year-old girl who had atonic partial seizure of the right leg accompanied by impaired equilibrium. This patient had a generalized tonic-clonic seizures before, and had been on anticonvulsant medication. Mild cataplexy of the right leg and flail trunk while standing occurred abruptly. Based on clinical symptoms, physiological findings, and an electroencephalogram taken at the time of seizure, the cataplexy of the right leg was diagnosed as epileptic seizures. After the dosage of anticonvulsant drug was increased, all symptoms disappeared completely. Cases of atonic partial seizure have been reported only rarely. In our case, atonic partial seizure was associated with nonepileptic equilibrium impairment, probably due to cerebral cortex dysfunction. This is an extremely rare occurrence.

Cerebral Cortex↗