Search PubMed⌕ Search

Biomedical subjects

I Nagai

Publications and source records attributed to I Nagai.

At least 55 records · Page 3Linked to original sources
PubMed1984

Two cases of hereditary diabetes insipidus, with an autopsy finding in one.

Two cases of hereditary diabetes insipidus (DI) are described, with an autopsy finding in one. The patients were brothers and 7 other relatives had symptoms of DI. The transmission of the disease in this family seemed to be an autosomal dominant trait with incomplete penetration. Both patients had the incomplete type of DI, which is diagnosed by the response of plasma AVP and the change in Uosm/Posm to 14 h water deprivation. The post-mortem examination in Case 1 showed that there was no atrophy of the supraoptic nucleus and paraventricular nucleus, but immunohistochemical studies revealed, that the paraventricular nucleus scarcely had any vasopressin positive cells in contrast to an autopsy control. This finding suggests that there may be a congenital defect in AVP synthesis in some cases of hereditary DI.

Adult↗
PubMed1984

Transaortic closure of ventricular septal defect in atrioventricular discordance with pulmonary stenosis or atresia. Results in five patients.

In five patients (aged 5 to 11 years) with atrioventricular discordance, pulmonary stenosis or atresia, and origin of the aorta from the right ventricle, transaortic closure of the ventricular septal defect was performed. Double-outlet right ventricle was confirmed in four patients. All patients underwent placement of an extracardiac valved conduit from the anatomic left ventricle to the pulmonary artery. Neither operative death nor postoperative complete heart block resulted. Postoperative follow-up periods were from 3 months to 4 years (average 35 months), and one patient who had no evidence of complete heart block died suddenly 2 years postoperatively. Aortic regurgitation developed in two patients from possible trauma during the operation: Regurgitation was mild (causing symptoms) in one patient who had had poor surgical exposure with a subpulmonic ventricular septal defect and a well-developed subaortic conus; it was trivial (asymptomatic) in the other patient. Transaortic ventricular septal defect closure, suturing a patch on the anatomic left ventricular side in patients with atrioventricular discordance and double-outlet right ventricle or similar anomalies, might help to avoid postoperative complete heart block if the aorta is large and the subaortic conus is not well developed.

Aorta↗
PubMed1983

Studies on the effects of hyperkalemia on serum and myocardial digoxin concentration in dogs.

The effects of hyperkalemia on serum and myocardial digoxin (DX) concentration was studied in conjunction with hemodynamic changes in 31 normal dogs. The myocardial DX concentration in the hyperkalemic (HK) group was significantly lower than that in normokalemic (NK) group, despite a significantly higher serum DX concentration in the HK group. In the HK group, the myocardial sodium concentration was significantly lower than in the NK group. Coincident with these biochemical changes, no increase of LV max dP/dt after DX administration was observed in the HK group. These results suggest that there might be competitive antagonism between myocardial uptake of potassium and DX.

Animals↗
PubMed1982

A battery powered operating table with a removable stationary column base and a detachable table top.

AC and DC powered operating tables were investigated from the viewpoint of safety and the following results were obtained: 1) With the increase in supply voltage, leakage from cables increased prominently. Only a low leakage cable showed a low leakage value. 2) AC powered operating tables showed a high leakage current, especially when in remote control. 3) A battery powered operating table with freely removable driving base and detachable table top function, which we developed, proved to have a satisfactory durability for actual clinical use and an extremely low level leakage of electricity (0.1-0.3 micro A). Moreover, our design incorporates every merit guaranteed by the usual operating table.

Electric Power Supplies↗
PubMed1979

Effect of transverse tubule-disruption on 14C-caffeine influx in frog skeletal muscle.

Effect of transverse tubule-disruption (T-disruption) on 14C-caffeine influx was studied using small bundles, consisting of 40 to 50 fibers, of frog semitendinosus muscle. The peak tension of caffeine contracture was inhibited by about 69% at 5 mM caffeine and by about 31% at 7 mM caffeine by T-disruption. In addition, the amount of caffeine influx in a small bundle was inhibited by about 52% at 5 mM caffeine and by about 28% at 7 mM caffeine by T-disruption, corresponding to the inhibition of the peak tension of caffeine contracture by T-disruption. These findings support our previous suggestion that caffeine enters the muscle fibers through the surface membrane and transverse tubuler membrane (T-membrane), and that the T-membrane contributes to the entry of caffeine more greatly at 5 mM caffeine than at 7 mM caffeine. Moreover, at 5 mM caffeine it was noted that there is a slight difference between the extent of inhibition of the caffeine influx and that of the peak contracture tension. From these results, it could be concluded that the inhibition of peak tension of caffeine contracture by T-disruption is mainly due to the inhibition of caffeine influx which occurs through the T-membrane and is partly due to the functional disturbance of the sarcoplasmic reticulum which is probably induced by T-disruption.

Animals↗
PubMed1979

Effect of SCN on potassium contracture in twitch muscle fibers of the frog.

The effect of SCN on potassium contracture, especially the time course and the mechanical inactivation of the contracture, was investigated using frog twitch muscle fibers. SCN increased the magnitude and the rate of rise of the potassium contracture tension and prolonged its time course. These effects of SCN depended on the concentration of K+ in the external medium and on the duration of pretreatment of the fibers with SCN-Ringer solution. The potentiating effect of SCN on the potassium contracture tension was pronounced at lower and moderate concentrations of K+ and this effect attained a maximum within 1 min after the pretreatment. In the contracture induced by exposure of the fibers to K-SCN-solution without the pretreatment, the time course of the contracture, especially the retardation of the spontaneous relaxation, was marked at higher concentrations of K+. This retarding effect of SCN attained a maximum at more than 10 min after the pretreatment with SCN-Ringer solution. SCN shifted the mechanical inactivation curve of potassium contracture toward lower concentrations of K+, as in the case of the activation curve, and markedly increased the rate of the inactivation induced by conditioning with 15 mM K+. In addition, SCN delayed the recovery of potassium contracture from the mechanical inactivation induced by preceding K-SCN-contracture. On the basis of these results, the sites and the mechanism of action of SCN on potassium contracture are discussed.

Animals↗
PubMed1978

Caffeine contracture in transverse tubules-disrupted fiber and effect of anomalous anions on the contracture in frog twitch fiber.

Caffeine contracture in transverse tubules-disrupted (T-disrupted) muscle preparation and the effect of anomalous anions (SCN and NO3) on the contracture in single twitch fibers or thin bundles consisting of 2 or 3 fibers of frog were investigated. The magnitude and the rate of rise of caffeine contracture tension were decreased by T-disruption and the decrease was more marked at lower concentrations of caffeine. No seasonal difference between summer and winter frogs on the effect of T-disruption on caffeine contracture was observed. On the other hand, the magnitude and the rate of rise of caffeine contracture tension in the intact preparation was increased by anomalous anions, whereas the rate of spontaneous relaxation of the contracture was decreased. The effect of SCN on caffeine contracture appeared 5 min after the pre-exposure of muscle preparation of SCN-Ringer solution, with the maximal effect appearing after 10 min. The threshold curve of caffeine contracture was shifted toward the lower caffeine concentrations by anomalous anions and the extent of the shift in the curve was more pronounced with SCN than with NO2. In contrast, the potentiating effect of these anions on the caffeine contracture completely disappeared in T-disrupted muscle preparation. On the basis of these results, the caffeine pathway to the sarcoplasmic reticulum, and the sites and mechanism of the action of anomalous anions on caffeine contracture are discussed.

Animals↗
PubMed1978

Clinical analysis of colour vision deficiencies with The City University test.

The City University colour vision test (CUCVT) was used for the examination of 158 subjects suffering from congenital colour vision defects (36 protanopes, 122 deutanopes) and its results were compared with that of an anomaloscope and of the panel D-15. 23% of the subjects classified as protanopes and 98% of the subjects classified as deuteranopes by means of the anomaloscope were also classified as such by means of the CUCVT, while 93% of the subjects classified as protanomalous and 90% of the subjects classified as deuteranomalous by means of the anomaloscope gave normal answers at the CUCVT. The results of the CUCVT were almost the same as with panel D-15 except protanopia. The colour spots of each plate of the CUCVT were plotted on a CIE chromaticity diagram and the results of this study are also reported.

Adolescent↗
PubMed1977

Peripheral vascular effects of glucagon, acetylocholine and dopamine with an implanted total artificial heart (TAH).

Three vasoactive drugs--glucagon, acetylcholine and dopamine were used in calves with an implanted TAH to study their mere vascular effects. We noticed that glucagon, besides being a potent vasodilator, affected the vascular system gradually rather than instantly. Also, it allowed for the gradual recovery of the system, thus avoiding sudden fluctuations in systemic and pulmonary blood pressures. Glucagon was found to have a unique capability of decreasing vascular resistance with only a slight drop in systolic pressure. Acetylcholine action was rather instant, exhibiting a sudden fall in both systolic and diastolic blood pressures. In animals with a TAH, dopamine seemed to work differently from that in subjects with an intact natural heart. While many investigators failed to see any change in pulmonary vascular resistance due to dopamine injection in subjects with an intact natural heart, we noticed about 20% increase in pulmonary vascular resistance (with a dose of 10 muGm/Kg). However, at low dosages of dopamine, we did not notice any appreciable change in pulmonary vascular resistance, which suggests that its action is dose dependent. We tend to believe that glucagon offers promising results in controlling the pulmonary hypertension in calves with a TAH. It is, also, our opinion that further investigation on the vascular effects of dopamine would reveal more pertinent and interesting results and solve the existing discrepancies.

Acetylcholine↗