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Biomedical subjects

H Kawata

Publications and source records attributed to H Kawata.

At least 127 records · Page 7Linked to original sources
PubMed1985

Some features of the electrically induced contracture in the frog skeletal muscle: reexamination of the post-anodal inhibition.

Some features of the electrically induced contracture were investigated by means of the partition polarization method in the toe muscles of a bullfrog. Under the current clamp condition and in the presence of tetrodotoxin, a biphasic contracture was induced by strong depolarizing pulses, 1 sec, in duration. The contracture was depressed either by lengthening the pulse interval or by reducing the external calcium concentration. Furthermore, the contracture was augmented by applying conditioning depolarization and inhibited by conditioning hyperpolarization without accompanying any noticeable changes in the test depolarization. Caffeine at a concentration of 1 mM depressed the inhibitory effect of pre-hyperpolarization. Strong hyperpolarizing pulses had no effect on the caffeine contracture, whereas a similar pre-hyperpolarization markedly suppressed the phenomenon on the post-contracture potentiation of twitch, induced by a powerful sustained depolarization. From these results it was suggested that calcium ions in the vicinity of the myoplasmic site of the transverse tubular membrane may play some role in generating and regulating the contracture. The possibility of direct contribution of calcium entering from the cell exterior in contracture generation, especially for the slow component, and its regulation was also discussed.

Animals↗
PubMed1985

[Clinical utility of tumor markers in gastric and colon cancer].

Serum TPA and CEA level were measured in patients with gastric or colon cancer during the course of surgical treatment, and those clinical utility was evaluated. Both markers level were shown to be highest in colon cancer, followed by gastric cancer, benign diseases, and healthy subjects. Late stage patients, especially inoperable patients or patients in recurrence showed significantly high TPA and CEA level compared to early stage patients. Both markers were considered to be useful not only postoperative following up for recurrence but also preoperative evaluation for resectability and prognosis and postoperative evaluation for the treatment itself.

Antigens, Neoplasm↗
PubMed1985

[The role of the body's defense against tumors by regional lymph nodes].

The role of bodily defense against tumor by regional lymph nodes was discussed in this study, especially focused on anti-tumor effect. Anti-tumor immune response was observed in regional lymph nodes in the tumor-bearing mouse. Advance of tumor or distance between lymph nodes and tumor effected the strength of the immune responses. In clinical study, anti-tumor immune response was observed similarly on draining lymph nodes of gastric cancer or colo-rectal cancer by measuring the PHA lymphocyte blastogenesis formation, the natural killer activity and the T-cell subpopulation. The response of regional lymph nodes was suppressed in early stage cases, while that of remote nodes was preserved comparatively. As is stated above, anti-tumor immune response was confirmed in draining lymph nodes. This suggested that at least for early gastric cancer without lymph node metastasis, surgical treatment with limited lymph node dissection should be considered in order to preserve bodily defense mechanism of regional lymph nodes.

Animals↗
PubMed1984

Effects of low Na on the tetanic contractility of frog skeletal muscle.

The effects of low Na on the tetanic contractility after trains of twitch were investigated in frog skeletal muscle. Tetanic tension was induced by a stimulation of 100 Hz for 400 msec every 5 min and a train of twitches (150 or 250) with 1 Hz was interposed between two successive tetani. When the Na concentration was reduced to 50% by replacement with choline, each twitch constituting the positive staircase during stimulus train was augmented as compared with those in normal Ringer. The amplitude of action potential during the staircase was smaller than that in normal Ringer and was gradually decreased, suggesting that low Na solution made the release of twitch-Ca from the sarcoplasmic reticulum in twitch more effective. Although the tetanic contractility in low Na was almost the same as that in normal Ringer before applying twitch train, it was more markedly inhibited after the train. The relative size of the inhibited tetanus had a correlation with the relative size of the potentiated twitch in both normal Ringer and low Na. This tetanus inhibition after the twitch train might be due to the suppression of action potential and/or due to some inhibitory factor in the excitation-contraction (E-C) coupling process.

Action Potentials↗
PubMed1984

Mechanism of inotropic action by hypotonic solution in the frog atrial muscle.

The effects of hypotonic solution on the mechanical activities and action potential of the bullfrog atrium were investigated. Exposure of muscle to hypotonic solutions (70% of normal solution) produced initially a transient increase in twitch after which twitch declined below the control level. The response is independent of the kinds of salts withdrawn to make the medium hypotonic and of the presence of beta-blocker (5 X 10(-7) M propranolol). The resting potential and the plateau level of action potential were little changed initially. When the twitch declined, a small amount of depolarization and a shortening of action potential duration were observed; however, the plateau level of action potential was not reduced. The initial increase in twitch was not observed, and only the gradual decline of twitch remained in the caffeine containing hypotonic solution. The weight of muscle increased 10% in the hypotonic solution. The resting tension was also increased transiently and then declined to reach a maintained plateau with exposure to hypotonic solution. In the 0-Ca2+ or caffeine containing medium, the transient component of contracture was suppressed but the plateau tension remained. It is suggested that the initial transient increase of twitch by the perfusion of the hypotonic solution was induced by the Ca2+ released from the sarcoplasmic reticulum (SR), and the resultant decline of twitch resulted from the depletion of Ca2+ from the SR and/or from the shortening of action potential duration.

Action Potentials↗
PubMed1984

[Evaluation of immune status in gastric cancer using Su-Ps skin test].

Immunotherapy for gastric cancer has been adopted by any institutes recently. However, immunoparameters which exactly express patients' immune status have not been determined. In this study, the Su-Ps skin test was tried to evaluate whether or not this reaction could become a usable immunoparameter. Conclusions were as follows: 1) Late-stage patients showed a significantly weak response in the Su-Ps skin test compared to early-stage patients when examined preoperatively. 2) Su-Ps skin reaction became stronger after gastrectomy in early-stage patients, while the contrary result was observed in late-stage patients. 3) Postoperative Su-Ps skin tests showed a stronger response than preoperative tests regardless of the patients' stage, when patients received OK-432 treatment. The Su-Ps skin test reaction seemed to be well-correlated with the patients' immune status as above, so that this test can be chosen for evaluation of immunotherapy.

Humans↗
PubMed1984

[Experimental study on the antitumor activity of regional lymph nodes during immunotherapy].

In ascites hepatoma MH134-bearing C3H/He mice, the hemolytic streptococcus preparation OK-432 was administered as model immunotherapy for malignant tumors, and the significance of the presence of regional lymph nodes and changes in cellular immunological competence were investigated. The antitumor effects of OK-432 were greater in tumor-bearing mice in which the regional lymph nodes were preserved than in those lacking regional lymph nodes, showing the significance of the presence of regional lymph nodes during immunotherapy. Regarding lymphocytes in the regional lymph nodes, the Thy 1,2 antigen positive cell ratio, PHA blast formation reaction, cytotoxic activity against YAC-1 cells and MH134 cells as the target cells were determined. Although these values were decreased in proportion to the progress of the tumor, the administration of OK-432 suppressed the decrease. In terms of the increase ratio of the values after the administration of OK-432, the effects of OK-432 on the regional lymph nodes were greater than those on other lymph nodes. It is presumed that immunotherapy suppressed a decrease in cellular immunological competence of regional lymph nodes in proportion to the progress of the tumor and allowed the recovery of the antitumor activity.

Animals↗
PubMed1983

A study on the mechanism of twitch potentiation by hypertonic solution in the frog atrial muscle.

Hypertonic solutions were found to exhibit both positive and negative inotropic effects on the contraction of the isolated atrial myocardium of bullfrog. The optimum tonicity for twitch potentiation was about 1.5 T. The mechanism for the positive inotropic action was investigated. The possibility of involvement of an increase in calcium influx during each action potential was excluded, since both the overshoot and the plateau of action potential were strongly depressed by perfusion of hypertonic solution. The effect on the time course of twitch potentiation was similar to that of muscle shrinkage, regardless of the type solute (sucrose, NaCl or LiCl) used for elevating the tonicity, except that excess sodium showed an initial rapid inhibitory phase of contraction. A marked post-rest potentiation was observed even after "zero" calcium perfusion, provided that the tonicity of the bathing medium was elevated previously. Potassium contracture occurred during the prolonged hypertonic perfusion in "zero" calcium condition. In addition, caffeine contracture was strongly augmented in hypertonic solution. The results suggest that an elevation in both the [Ca2+]i and amount of calcium bound intracellularly may play an important role in the positive inotropic action.

Action Potentials↗
PubMed1983

Paradoxical after-potentiation of the myocardial contractility by lanthanum.

Lanthanum of 0.1 to 0.2 mM caused a twitch inhibition and further showed a marked, long-lasting twitch potentiation during washout in both ventricular strips of bullfrog and atrial or papillary muscles of guinea-pig. It was found that the effect was more conspicuous in the frog heart. A similar potentiation was observed by applying gadolinium instead of lanthanum. The participation of endogeneous catecholamine release is unlikely since the positive inotropic effect was never affected by the presence of beta-adrenergic blocker. The potentiation was not accompanied by any increase in the action potential plateau, suggesting independence of the phenomenon on the calcium current. A marked elevation of the resting tension was produced during a long-term lanthanum perfusion, reflecting the increase in the intracellular calcium level. On the other hand, transient increase in the resting tension was frequently observed on returning to normal Ringer solution. The latter change seemed to result from a transient increase in the resting permeability to calcium ions. The negative or positive inotropic effect by increasing or lowering the external sodium concentration observed under the control condition was strongly depressed during the twitch potentiation. In addition, sodium-free contracture induced by solutions isotonically replaced with sucrose or potassium chloride was augmented both during lanthanum perfusion and during its washout. These results suggest the possibility that the elevation of the intracellular calcium level due to inhibition of Na-Ca exchange mechanism and/or increase in the calcium permeability is the principal cause for the twitch potentiation caused by lanthanum washout.

Action Potentials↗
PubMed1983

Effects of twitch train on the tetanic contractility of the frog skeletal muscle.

The effects of twitch trains on the contractility of succeeding tetani were investigated in the frog toe muscle. The changes in isometric tension and its first derivative were analyzed. Tetani of 1 sec duration were induced every 5 min and trains of twitches (less than 250) with 0.1 to 3 Hz were interposed between two successive tetani. A twitch train which clearly shows an ascending staircase exerted at least three different effects on the following tetani. These were a rapidly decaying potentiation (P1), a slowly decaying potentiation (P2), and an inhibitory effect (I) which was regarded as fatigue. These after-effects were modified by various interventions. Increasing of the twitch frequency at a constant number of stimuli augmented both the potentiating and the inhibiting effects. When the bath temperature was lowered to 4 degrees C, the potentiation was masked by a marked inhibition. At a higher temperature (28 degrees C) the potentiating effect was facilitated. Prolonged perfusion of low concentration (0.5 mM) of caffeine mimicked the effects of low temperature. Effects of twitch train on the contracture induced by 5 mM caffeine were examined and it was found that the repetitive twitches had no effect on the following caffeine contracture. Although the exact mechanism for these after-effects was not clear, it was assumed that the intracellular calcium turnover may play some role in the observed phenomena.

Animals↗
PubMed1982

[Liver cirrhosis and liver cancer--types, clinical courses, and progress in their treatment].

There have been several controversies about classification of liver cirrhosis between Western countries and Japan. By the follow-up studies for 5 years on 478 cirrhotic patients diagnosed in Osaka area, relatively higher survival rates were found in cases without HBs-antigen and in heavy drinkers, whereas cases of cryptogenic type showed poor prognosis. The most marked progress in diagnostic procedures in this field seems to be several imaging techniques such as scintiphotography, U.S. echography and computed tomography. Analysis obtained by serial observations on imaging films would be valuable in differentiation between hepatoma and liver cirrhosis. Remarkable improvement has been shown in examinations on etiologic factors, degree of impairment of liver cell functions and precise evaluation of pathophysiological status of patients. Although it is our great regret that radical procedure to cure patients suffering from liver cirrhosis or hepatoma has not yet been known, several palliative treatments have become practical in recent years. For example, percutaneous transhepatic portal occlusion or injection of sclerosing agents for bleeding esophageal varices, parenteral feeding using adjusted amino acids pattern solution for impending coma and selective arterial embolization by sponges or coils infused with anticarcinogenic drugs for inoperable hepatoma have been used and effective to prolong survival period of these patients.

Ascites↗
PubMed1980

Digoxin degradation in acidic dissolution medium.

The release of digoxin and its simultaneous conversion to digoxigenin bisdigitoxoside, digoxigenin monodigitoxoside, and digoxigenin in a USP dissolution test medium were followed by high-pressure liquid chromatography. Two products, Tablets A and B, were manufactured by solvent deposition and simple blending methods, respectively. Tablet A released digoxin faster than Tablet B in distilled water and in artificial intestinal juice, and no decomposition was observed. In the USP dissolution test medium, the rate of hydrolysis to digoxigenin bisdigitoxoside was almost equal to that of hydrolysis to digoxigenin monodigitoxoside, and a comparatively large formation rate of digoxigenin was observed. Concentrations of digoxin and its decomposition products were described by differential equations that included dissolution rates of digoxin (rapidly dissolving digoxin and digoxin crystals) and an apparent hydrolysis rate. In the earlier stage of dissolution, hydrolysis was rate determining; in the later stage, dissolution became the rate-determining step for overall digoxin degradation. To suppress digoxin hydrolysis in the USP dissolution test medium, a developmental formulation study was performed. The incorporation of magnesium oxide and magnesium hydroxide-aluminum hydroxide in the tablet formulations inhibited digoxin hydrolysis by 15.3 and 14.5%, respectively, after dissolution for 30 min without serious delay of drug release.

Acids↗