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Biomedical subjects

T Kagawa

Publications and source records attributed to T Kagawa.

At least 127 records · Page 7Linked to original sources
PubMed1987

[Musical systolic murmur produced by oscillation of the systolic anterior motion of the mitral apparatus: relation to the genesis of Still's murmur].

The genesis of a musical systolic murmur produced by systolic anterior motion (SAM) of the mitral apparatus was investigated in four patients using phonocardiography and echocardiography. Two patients (Case 1 and 3) had hypertrophic cardiomyopathy (one, the obstructive type; the other, the nonobstructive type) and the remaining two (Case 2 and 4) had redundant chordae tendineae. 1. In every patient, regular oscillation of the SAM was observed, coinciding in time with the musical systolic murmur, which was simultaneously recorded. The fundamental frequency of the musical systolic murmur was recorded as integrally multiplied numbers of the SAM. Such regular oscillation was not observed in the echograms of other cardiac structures. In a patient with hypertrophic obstructive cardiomyopathy (Case 1), both the amplitude and oscillation of the SAM were increased by amyl nitrite inhalation, and were decreased by angiotensin II infusion. Correspondingly, the intensity of the musical murmur showed similar reaction. No findings suggestive of mitral valve prolapse or mitral regurgitation were found in any patients. Therefore, the oscillation of the SAM produced by blood ejected from the left ventricle was considered the source of the musical systolic murmur in these patients. 2. Two patients with redundant chordae tendineae had no clinical abnormalities except for chordal redundancy; therefore, the musical murmur in these cases was considered to be functional. Particularly, one of them was compatible in character with the so-called Still's murmur. In conclusion, the regular oscillation of the SAM may be the source of the musical systolic murmur, and they must be taken into consideration as part of the genesis of Still's murmur.

Adolescent↗
PubMed1987

[Mitral regurgitation in mitral valve prolapse: its mechanisms and time course].

To clarify the mechanisms and time course of mitral regurgitation (MR) in mitral valve prolapse (MVP), the relationship between the timing of MR flow patterns on pulsed Doppler echocardiography and phase of mitral valve prolapse on two-dimensional echocardiography was investigated. 1. Thirty-seven patients with MVP were followed by pulsed Doppler echocardiography for one to six years with an average of 2.5 years. At the initial examination, the patients were classified in five subsets on the basis of the presence or timing of MR: 10 without MR, five with early systolic MR, one with mid-systolic MR, 15 with late systolic MR and six with pansystolic MR. During the follow-up period, the timing of MR did not change in 21 patients (three with no MR, five with early systolic MR, seven with late systolic MR and six with pansystolic MR). Various changes were observed in 16 patients, i.e., developments of late systolic MR from no MR in four, of pansystolic from no MR in three, from late systolic MR in five and from mid-systolic MR in one, and disappearing late systolic MR in three. 2. Mitral annular diameter and the prolapsing phase of 118 patients with MVP (44 without MR, eight with early systolic MR, 30 with late systolic MR and 36 with pansystolic MR) were examined by long-axis two-dimensional echocardiography. The mitral annular diameter in patients with early systolic MR was significantly less than that of other MR groups, and the diameter in patients with pansystolic MR was markedly increased. The timing of MR was determined according to the prolapsing phase and the grade of the prolapse and the systolic size of the mitral annulus. Six of the eight patients with early systolic MR first had early systolic prolapse of either mitral leaflet, and then the regurgitant gap of the mitral valve orifice was plugged by the prolapsing leaflet and/or the narrowed mitral annulus during mid-to-late systole. In 18 of the 30 patients with late systolic MR, the grade of prolapse of the mitral valve during mid-to-late systole was more severe, compared with that of early systole. The results of the present study indicated that the occurrence of MR in MVP is various in timing (early, mid-, late or pansystole) and shows various changes the during follow-up study, and that pulsed Doppler echocardiography allows phase analysis of MR in MVP.

Adult↗
PubMed1986

Pulmonary function after lobectomy in children under ten years of age.

A long-term follow-up study on pulmonary function in twelve lobectomized children under ten years of age at the time of surgery was performed to determine the patterns of compensation. In the patients over ten years old at the time of the test performed over two years postoperatively, there was neither compensatory regeneration nor compensatory overdistension of the remaining lung tissue. However, there appeared to be an increase in the vital capacity, probably due to the growth of surrounding tissue such as thorax, respiratory muscles, and diaphragm. In contrast, the children tested under the age of eight years showed evidence of mild overdistension during the early postoperative period, but not at two years. There was no sign of overdistension in the patients over ten years of age at the time of testing.

Age Factors↗
PubMed1986

Protection against oxygen-induced reperfusion injury of the isolated canine heart by superoxide dismutase and catalase.

While oxygen-derived free radicals have been implicated in the pathogenesis of myocardial injury, the exact nature of this injury is still unclear. To test the hypothesis that oxygen-induced injury may influence the recovery of cardiac function from ischemic damage, we used an oxygen free radical scavenger, superoxide dismutase (SOD), together with catalase, during the reperfusion of isolated canine heart which had been subjected to 15 min of normothermic ischemic arrest followed by 2 hr of hypothermic cardioplegic preservation using a modified Collins solution. Determinations of thiobarbituric acid reactive substances and coenzyme Q10 within the myocardium showed that the treatment with SOD and catalase was capable of inhibiting lipid peroxidation induced by reperfusion. This inhibition was apparently associated with the improvement of myocardial energy metabolism and cardiac performance. Coronary flow was significantly higher in the heart treated with SOD and catalase during the working stage with a corresponding increase in oxygen consumption. Myocardial adenosine triphosphate (ATP) was partially, but significantly restored during reperfusion in these hearts whereas no restoration was observed in the heart without the enzymes. The treatment with SOD and catalase also improved left ventricular stroke work index and left ventricular maximum dp/dt at an early stage of the working mode. These results suggest that the use of SOD and catalase during reperfusion can protect the ischemic heart against reperfusion injury by scavenging oxygen-derived free radicals.

Animals↗
PubMed1986

Evaluation of uneven distribution of VA/Q ratio from data on exchange of respiratory gases.

A new approach has been developed for evaluating uneven distribution of ventilation/perfusion ratio, VA/Q, based on a two-compartment model with a reciprocal VA/Q relation. The VA/Q ratios were expressed by mu . (1-rho)/rho and mu . rho/(1-rho), where mu and rho were referred to as the "ideal" VA/Q ratio and unevenness factor, respectively. During steady state breathing, arterial blood was analyzed for PO2 and PCO2, and end-tidal PCO2 as well as the gas exchange ratio, R, was measured. After steady state breathing a rebreathing experiment was performed, and the arterial-venous O2 content difference, (a-v)CO2, was measured, and then, multiplying it by R, the venous-arterial CO2 content difference, (v-a)CCO2, was obtained. Referring to these values the mixed venous PO2 and PCO2 were estimated from arterial PO2 and PCO2, using the O2 and CO2 dissociation curves. The VA/Q line and iso-R line were drawn to find mu, and further, total arterial, and alveolar PO2 and PCO2 of the two-compartment model were computed by changing both rho and the mixing weight factor, phi. The phi value was determined so as to make the above PO2-PCO2-locus pass through the measured arterial PO2 and PCO2. The rho value was selected so that the computed alveolar PCO2 fitted to the end-tidal one. The experiments were performed on 8 normal subjects in normoxia and hyperoxia with PIO2 245 Torr. The mean phi values in normoxia and hyperoxia were 0.50 and 0.56, respectively. The mean rho values in normoxia and hyperoxia were 0.438 and 0.428, respectively. The VA/Q ratio was decreased in hyperoxia because of a decrease in VA value.

Carbon Dioxide↗
PubMed1986

Numerical solution of partial differential equations describing the simultaneous O2 and CO2 diffusions in the red blood cell.

To describe the overall gas exchange rates in red blood cells (RBC), a computer program for solving the diffusion equations for O2, CO2, and HCO3-that accompany the chemical reactions of Bohr- and Haldane-effects was developed. Three diffusion equations were solved alternatively and repeatedly in an increment time of 2 ms. After solving the diffusion equations the Po2, O2 saturation (So2), Pco2, pH, and HCO3-content were corrected by using the Henderson-Hasselbalch equation, where the buffer value was newly derived from the CO2 dissociation curve. In computing the Haldane effect, the buffer value was taken to be 44mmol X l(RBC)-1 X pHc-1, so that the change in intracellular dissolved CO2 caused by the So2 change was fully compensated by the subsequent CO2 diffusion. The oxygenation and deoxygenation rate factors of hemoglobin were assumed to be 2.09 X (1-S)2.02 and 0.3s-1 X Torr-1, respectively. The Po2 change due to the Bohr-shift was computed from Hill's equation, in which the K value was given by a function of the intracellular pH. When the parameter values thus far measured were used, the computed Bohr- and Haldane-effects coincided well with the experimental data, supporting the validity of the equations. The overall gas exchange profiles calculated in the pulmonary capillary model showed that the CO2 equilibration time was significantly longer than the oxygenation time.

Bicarbonates↗
PubMed1985

Analysis of endodontic therapy in patients irradiated for head and neck cancer.

The outcome of endodontic therapy in 16 patients irradiated for head and neck cancer was studied. Thirty-five postradiation endodontically treated teeth (54 roots) were included in the study. The follow-up period ranged from 6 months to 54 months. At the time of last follow-up, 46 of 54 roots were being maintained. No osteoradionecroses were seen in association with teeth that had been endodontically treated. From this review, it is clear that endodontic therapy is a viable method of treating diseased teeth in patients irradiated for oral neoplasms.

Aged↗
PubMed1985

Allocation and Turnover of Photosynthetically Assimilated CO(2) in Leaves of Glycine max L. Clark.

The allocation and turnover of photosynthetically assimilated (14)CO(2) in lipid and protein fractions of soybean (Glycine max L. Clark) leaves and stem materials was measured. In whole plant labeling experiments, allocation of photosynthate from a pulse of (14)CO(2) into polymeric compounds was: 25% to proteins in 4 days, 20% to metabolically inert cell wall products in 1 to 2 days, 10% to lipids in 4 days, and 4% to starch in 1 day. The amount of (14)C labeled photosynthate that an actively growing leaf (leaf 4) used for its own lipid synthesis immediately following pulse labeling was about 25%. The (14)C of labeled proteins turned over with half-lives of 3.8, 3.3, and 4.1 days in leaves 1, 2, and 3, respectively; and turnover of (14)C in total shoot protein proceeded with a half-life of 5.2 days. Three kinetic (14)C turnover patterns were observed in lipids: a rapid turnover fraction (within a day), an intermediate fraction (half-life about 5 days), and a slow turnover fraction. These results are discussed in terms of previously published accounts of translocation, carbon budgets, carbon use, and turnover in starch, lipid, protein, and cell wall materials of various plants including soybeans.

Journal Article↗