1.EFFECTS OF THYROID HORMONE ON SARCOPLASMIC RETICULUM Ca2+ UPTAKE AND CONTRACTILE PROPERTIES IN RAT SOLEUS MUSCLE
TAKASHI YAMADA ; MASANOBU WADA
Japanese Journal of Physical Fitness and Sports Medicine 2004;53(5):509-517
The effect of hyperthyroidism on the contractile properties and Ca2+ sequestering abilities by the sarcoplasmic reticulum (SR) in the soleus muscles was examined in rats treated with thyroid hormone (3, 5, 3'-triiodo-L-thyronine, T3) (300μg/kg body weight) for 3, 7 and 21 days. At the end of a given treatment period, the right or left soleus muscle was mounted isometrically at 30°C, and stimulated directly using supramaximal current intensity. A twitch contraction was elicited by a 1 msec square-wave pulse and a tetanic contraction by 20 Hz stimulation for 600 msec. To evaluate fatigue resistance, muscles were stimulated at 40 Hz for 350 msec with tetani repeated at an interval of 2 sec during a 4-min period. Another soleus muscle was used, for analysis of SR Ca2+ -uptake rate and SR Ca2+ -ATPase activity. Pronounced increases in SR Ca2+ -uptake rate and ATPase activity were observed after T3 treatment periods longer than 6 days. These alterations were accompanied by decreases in twitch and tetanic tension, half-relaxation time, and fatigue resistance. The T3-treated muscles stimulated at 20 Hz relaxed during the interval between successive stimuli, indicating that the mechanical fusion of tetanic contractions was incomplete. SR Ca2+ uptake rate was significantly correlated both to tetanic tension and to fatigue resistance. These data suggest that there may be a causal relationship between changes in SR Ca2+ uptake and the loss of muscular strength in the hyperthyroid soleus.
2.Synergistic Action of Amrinone and Dibutyryl Cyclic AMP on Myocardial Metabolism and Hemodynamics in the Early Postoperative Period Following Open-Heart Surgery.
Yoshihito Irie ; Takashi Yamada
Japanese Journal of Cardiovascular Surgery 1998;27(3):143-147
Effects of amrinone and dibutyryl cyclic AMP (DBcAMP) on hemodynamics and myocardial metabolism were studied in 16 patients in the early postoperative period following open-heart surgery. Amrinone was administered continously at 10μg/kg/min for 5 hours and DBcAMP at 12μg/kg/min was infused concomitantly for the last 1 hour. Amrinone increased SVI, and decreased HR, PCWP, arterial systolic blood pressure, double product and central temperature difference significantly. Following concomitant administration of DBcAMP for 1 hour, further increase of CI, O2 delivery, blood sugar and insulin were observed. Significant decrease of excess lactate from 9.31±3.27 to -1.31±1.83mg/dl (p<0.05) showed that anaerobic metabolism improved in the myocardium after amrinone administration, and the effect improved further to -3.64±1.8mg/dl following concomitant administration of DBcAMP. These data demonstrate that amrinone has beneficial effects on hemodynamics and myocardial metabolism, and following supplementary administration of DBcAMP, further improvement in hemodynamics was observed.
3.Characteristics and mechanisms of low-frequency muscle fatigue: alterations in skeletal muscle
Masanobu Wada ; Takashi Yamada ; Satoshi Matsunaga
Japanese Journal of Physical Fitness and Sports Medicine 2012;61(3):297-306
Repeated contractions of skeletal muscle cause fatigue, as manifested by a reduced ability to produce force and slowed contraction. During studies of muscle fatigue, a phenomenon known as low-frequency fatigue (LFF) was observed in human skeletal muscles. It is characterized by a greater loss of force in response to low- versus high-frequency muscle stimulation and a long period of time for full recovery. This force deficit is most likely to be owing to disturbances in sarcoplasmic reticulum (SR) Ca2+ release and/or reductions in myofibrillar Ca2+ sensitivity. Studies on metabolites have implied that inorganic phosphate and Mg2+ might have some role in reduced SR Ca2+ release that occurs immediately after fatiguing contraction. In addition, recent experiments have shown that impaired myofibril function may relate to increased nitric oxide and hydroxyl radical production, whereas deterioration of SR function may be attributable to increased superoxide production, elevation of cytoplasmic Ca2+ concentration and/or decreased muscle glycogen. Finally, we will discuss possible proteins which are affected and contribute to the development of LFF.
4.A Case of Redo Aortic Valve Replacement by Right Minithoracotomy Approach with Port Access for Aortic Valve Stenosis after Coronary Artery Bypass Grafting
Takanori Tokuda ; Takashi Murakami ; Yuki Yamada ; Takashi Yamamoto ; Satoru Oya
Japanese Journal of Cardiovascular Surgery 2012;41(6):320-322
We report a case of redo aortic valve replacement by right minithoracotomy approach for aortic stenosis after coronary artery bypass grafting (CABG). An 81-year-old man was followed-up once a year for 9 years after CABG. He complained of increasing respiratory distress, showed narrowing of the aortic valve area, elevation of the aortic valve pressure gradient, and tricuspid valve regurgitation by echocardiography. He was admitted for surgery. We considered minimally invasive operation would be better for him and performed aortic valve replacement (Carpentier-Edwards Perimaunt valve 19 mm) by a right minithoracotomy approach because graft injury could occur by median sternotomy after CABG, and he had the risks of advanced age, low activities of daily living, and mild dementia. His postoperative course was uneventful. On echocardiography performed at postoperative days 9, the ejection fraction recovered to 75% from 53% before surgery and the mean aortic valve pressure gradient was 8 mmHg. He was discharged on postoperative day 12. Right minithoracotomy approach with port access is a good option for redo operation for aortic valve stenosis after CABG.
6.Adrenocortical Function during Hypothermia. Effect of low temperature on the corticoidogenesis in cultured bovine adrenocortical cells.
Noboru NAKAMICHI ; Kenji YAMADA ; Akiyoshi NIITSU ; Takashi MATSUI
The Journal of The Japanese Society of Balneology, Climatology and Physical Medicine 1993;56(3):157-162
Effects of hypothermia on corticoidogenesis (CG) were investigated in primary cultured bovine adrenocortical cells. In order to evoke CG, adrenocorticotropic hormone (ACTH), dibutyryl cyclic AMP (db-cAMP), and high K+ were used. In the presence of the above mentioned secretagogues, cells were incubated at 37°C, 27°C, and 20°C for 1 hour. Although there was no difference between the ACTH-induced CGs at 37°C and 27°C, CG was significantly lower at 20°C. Both db-cAMP and high K+-induced CGs were significantly lower at 27°C, and were not observed at 20°C.
These results indicate that CG is not affected by moderate hypothermia, and is not eliminated even by deep hypothermia. It is also suggested that ACTH influences not only adenylate cyclase and Ca2+ channels, but also various processes of glucocorticoid production and could evoke CG at 20°C in bovine adrenocortical cells.
7.CHANGES IN SARCOPLASMIC RETICULUM Ca2+-SEQUESTERING CAPACITY DURING RECOVERY FOLLOWING HIGH-INTENSITY EXERCISE
TAKAAKI MISHIMA ; TAKASHI YAMADA ; MAKOTO SAKAMOTO ; MASANOBU WADA
Japanese Journal of Physical Fitness and Sports Medicine 2006;55(5):503-512
The purpose of this study was to investigate changes in sarcoplasmic reticulum (SR) Ca2+-sequestering capacity in rat fast-twitch plantaris (PL) and slow-twitch soleus (SOL) muscles during recovery after high-intensity exercise. The rats were subjected to treadmill runs to exhaustion at the intensity (10% incline at 50 m/min) estimated to require 100% of maximal O2 consumption. The muscles were excised immediately after exercise, and 15, 30 and 60 min after exercise. Acute high-intensity exercise evoked a 27 % and 38 % depression (P<0.05) in SR Ca2+-uptake rate in the PL and SOL, respectively. In the PL, uptake rate remained lower (P<0.05) at 30 min of recovery but recovered 60 min after exercise. These alterations were paralleled by those of SR Ca2+-ATPase activity. On the other hand, SR Ca2+-uptake rate in the SOL recovered 15 min after exercise. Unlike the PL, discordant time-course changes between SR Ca2+-ATPase activity and uptake occurred in the SOL during recovery. SR Ca2+-ATPase activities were unaltered with exercise and elevated (P<0.05) by 25, 30 and 30% at 15, 30 and 60 min of recovery, respectively. These results demonstrate that SR Ca2+-sequestering ability is restored faster in slow-twitch than in fast-twitch muscle during recovery periods following a single bout of high-intensity exercise and suggest that the rapid restoration of SR Ca2+-sequestering ability in slow-twitch muscle could contribute to inhibition of disturbances in contractile and structural properties that are known to occur with raised myoplasmic Ca2+ concentrations.
8.EFFECT OF HIGH-INTENSITY TRAINING AND ACUTE EXERCISE ON Ca2+-SEQUESTERING FUNCTION OF SARCOPLASMIC RETICULUM : ROLE OF OXIDATIVE MODIFICATION
SATOSHI MATSUNAGA ; TAKAAKI MISHIMA ; TAKASHI YAMADA ; MASANOBU WADA
Japanese Journal of Physical Fitness and Sports Medicine 2008;57(3):327-338
To investigate the influences of high-intensity training and/or a single bout of exercise on in vitro Ca2+-sequestering function of the sarcoplasmic reticulum (SR), the rats were subjected to 8 weeks of an interval running program (final training : 2.5-min running×4 sets per day, 50 m/min at 10% incline). Following training, both trained and untrained rats were run at a 10% incline, 50 m/min for 2.5 min or to exhaustion. SR Ca2+-ATPase activity, SR Ca2+-uptake rate and carbonyl group contents comprised in SR Ca2+-ATPase activity were examined in the superficial portions of the gastrocnemius and vastus lateralis muscles. For rested muscles, a 12.7% elevation in the SR Ca2+-uptake rate was induced by training. Training led to improved running performance (avg time to exhaustion : untrained-191.1 vs trained-270.9 sec ; P<0.01). Regardless of training status, a single bout of exercise caused progressive reductions in SR Ca2+-ATPase activity and SR Ca2+-uptake rate. Increases in carbonyl content only occurred after exhaustive exercise (P<0.05). At both point of 2.5-min and exhaustion, no differences existed in SR Ca2+-sequestering capacity and carbonyl content between untrained and trained muscles. These findings confirm the previous findings that oxidative modifications may account, at least partly, for exercise-induced deterioration in SR Ca2+-sequestering function ; and raise the possibility that in the final phase of acute exercise, high-intensity training could delay the progression of protein oxidation of SR Ca2+-ATPase.
9.The Optimum Temperature of the Retrograde Continuous Blood Cardioplegia in Coronary Artery Bypass Grafting.
Noritsugu Morishige ; Tadashi Tashiro ; Takashi Yamada ; Michio Kimura
Japanese Journal of Cardiovascular Surgery 2002;31(4):252-257
Myocardial oxidative stress during retrograde continuous blood cardioplegia (RCBC) was evaluated in 35 patients undergoing elective aortocoronary bypass surgery. The patients were divided into three groups: Group C (n=12) received cold (20°C) RCBC, Group T (n=11) received tepid (30°C) RCBC, and Group W (n=12) received warm (36°C) RCBC. Myocardial oxidative stress was assessed by measuring the release of oxidized glutathione (GSSG), malondialdehyde (MDA), and myeloperoxidase (MPO) in the coronary sinus plasma before aortic clamping, at 1, 5, and 10min after unclamping. Myocardial oxygen uptake and lactate release were assessed at the same times. Both the hemodynamic recovery and the creatine kinase MB (CKMB) activity were measured perioperatively until 24h after unclamping. In Group C, a significant coronary sinus release of GSSG was found in the early reperfusion period in comparison to Groups T and W. However, the peak CK-MB activity was significantly lower in Group T than in Group W. No significant difference in the release of MDA or MPO was noted in the three groups. The recovery of oxygen uptake after unclamping was rapid in Group T. The recovery in the left and right ventricular functions and the myocardial lactate release were similar in the three groups. In conclusion, tepid RCBC is considered to protect the myocardium from ischemia-reperfusion injury better than cold or warm blood cardioplegia under retrograde continuous perfusion.
10.Program-improvement progress and future tasks of Inohana Interprofessional Education
Ikuko Sakai ; Mayumi Asahina ; Takashi Maeda ; Yuko Sekine ; Kana Kurokochi ; Kyoko Yamada
Medical Education 2014;45(3):153-162
This report summarizes the Inohana Interprofessional Education (Inohana IPE) program and describes its current achievements and improvement process. Since 2007, a total of 5,679 students have participated in the program. Students who have graduated include 335 from the Faculty of Nursing, 197 from the Faculty of Medicine, 84 from the Faculty of Pharmaceutical Sciences.
Through Inohana IPE we have created an environment that encourages students’ self-directed learning and the setting of behavioral objectives and have refined the program contents and evaluation method. As the first phase of the improvement, we developed competencies for interprofessional collaboration with 6 components and then created a matrix of learning-achievement goals and 4 learning steps based on the competencies. Furthermore, the number of faculty members participating in the program has increased.
The two main tasks for the future are to develop an IPE program for nursing and to integrate IPE for basic education and continuing education.