Biomedical subjects

M Ohnaka

Publications and source records attributed to M Ohnaka.

At least 37 records · Page 2Linked to original sources

PubMed1999

[Coronary artery bypass surgery in octogenarian].

Between May 1992 and December 1997, 14 parents aged 80 or older underwent CABG with cardiopulmonary bypass. (Group A: mean age 82.1 +/- 1.73). This group was compared with 127 patients aged 70s. (Group B: mean 73.3 +/- 0.70). Left main trunk stenosis was more frequent in group A (p < 0.05), and number of patient who had old myocardial infarction was also frequent (p < 0.05). Emergency operation and preoperative use of intra aortic balloon pump was frequent in group A (p < 0.05). While there was no significant change in the number of graft per patient and used number of internal thoracic artery between the two groups, postoperative complications such as atrial arrhythmia and respiratory failure was appeared more frequently in group A (p < 0.05). The hospital mortality did not differ between the groups (21.4% for group A and 14.2% for group B). In group A, 11 patients are alive without recurrence of angina. In conclusion, while there is many problems pre and post operative term, CABG in over 80 years patients of age was satisfactory result, so we should not exclude octogenarian because of age alone.

Aged↗

PubMed1999

[Emergency coronary artery bypass grafting for acute coronary syndrome].

Emergency CABG for acute coronary syndrome (ACS) was studied. Sixty patients had CABG for medically refractory UAP, 78 patients for AMI and 8 patients for post-infarction angina (PIA). In UAP group 7 patients (12%) died postoperatively, mainly due to perioperative myocardial infarction (PMI) and operative complications. In AMI group, 26 patients (33%) died, 14 of them due to myocardial failure. The operative mortality was extremely high in shock-state patients group (48%) and cardiac pulmonary arrest state patients group (85%). Operative result was poor in those patients whose infarct-related artery was not recanalized preoperatively. Operative mortality was 13% in PIA group. It was concluded that the reduction of mortality of those patients required much refined myocardial preservation technique and powerful mechanical assist system to support the postoperative myocardial failure.

Aged↗

PubMed1999

[A case who needed additional Daggett's procedure for residual shunt after infarction exclusion technique for post-infarction ventricular septal perforation].

A 71-year-old woman had the surgical repair of post-infarction ventricular septal perforation with infarction exclusion technique. Three days after operation, residual shunt was observed by echocardiogram and she developed cardiac failure. Pulmonary to systemic flow ratio was 2.1, and pulmonary artery pressure was 42/23 (33) mmHg. Additional surgery for residual shunt was performed 22 days after the first operation. The part of Xenomedica patch was found loosely floating in the LV cavity. The infarcted myocardium was firm enough to closed directly, so a double Hemashield cardiovascular fabric was sutured on the left side of the perforated septum around VSP (Daggett's Procedure). The ventriculotomy was closed including the fabric with two felt strips. The postoperative course was uneventful. Though infarction exclusion technique has the advantage in many cases, much attention must be paid to prevent residual shunt.

Aged↗

PubMed1998

Intracoronary aspiration thrombectomy for acute myocardial infarction.

To investigate the pathogenesis of acute myocardial infarction (AMI) and values of intracoronary aspiration thrombectomy (ICAT), we applied ICAT to reperfusion therapy using generally available intracoronary catheters to aspirate intracoronary occlusive tissues. We assigned ICAT or primary percutaneous transluminal coronary angioplasty (PTCA) to patients with evolving AMI (Thrombolysis In Myocardial Infarction (TIMI) trial grade 0), and investigated primary histopathologic, clinical, and angiographic outcomes in 43 patients treated with ICAT alone or followed by PTCA, and compared the outcomes with those in 48 patients treated with primary PTCA. No major complications (procedural death, emergent bypass graft surgery) occurred. Reconalization (TIMI grade 3 and 2) was achieved in 25 patients (58%) with ICAT alone and in 39 patients (91%) with ICAT alone or followed by PTCA. Aspirated thrombi were defined as recent thrombi in 21 cases (49%), atheroma in 6 (14%), no thrombi in 13 (30%), and organized thrombi in 1 case. In cases of recent thrombi, ICAT alone provided recanalization more frequently than in those of atheroma or no thrombi (18 of 21 [86%], 3 of 6 [50%], 4 of 13 [31%], respectively; p < 0.05; recent thrombi vs atheroma or no thrombi). There were no significant differences in primary recanalization rate (ICAT alone or followed by PTCA vs primary PTCA; 91% vs 92%) or incidence of complications between the 2 strategies. These results indicate that although the pathogenesis of AMI is heterogeneous in each individual case, intracoronary thrombus contributes little to the pathogenesis of average AMI, and therefore mechanical approaches may be feasible to maximize reperfusion therapies for AMI.

Angioplasty, Balloon, Coronary↗

PubMed1998

A lipoprotein lipase activator, NO-1886, improves endothelium-dependent relaxation of rat aorta associated with aging.

Endothelial function is closely related to development of atherosclerosis and is impaired with aging. The novel compound NO-1886, 4-diethoxyphosphorylmethyl-N-(4-bromo-2-cyanophenyl)benzamid e, is a lipoprotein lipase activator and its long term administration protects against the development of experimental atherosclerosis in animals. The aim of this study was to ascertain whether NO-1886 ameliorates the impaired endothelium-dependent relaxation of rat aorta associated with aging. NO-1886 (50 mg/kg p.o.) was administered to 7-month old rats for 3 months. Plasma lipid, glucose and insulin levels in old control rats (10 months of age) were significantly higher than those of young rats (2 months of age). NO- 1886 decreased plasma triglyceride levels (old rats, 233+/-10 mg/dl; old rats + NO-1886, 172+/-16 mg/dl, P < 0.01) and increased plasma high density lipoprotein (HDL) cholesterol level (old rats, 72+/-6 mg/dl; old rats + NO-1886, 142+/-6 mg/dl, P < 0.001) in old rats, but had no effects on plasma glucose or insulin. The endothelium-dependent relaxation of the thoracic aorta caused by histamine was significantly impaired in old rats (% relaxation at 10(-5.5) M histamine: young rats 25.4+/-3.1%; old rats 14.1+/-1.9%, P < 0.01), an effect completely prevented by NO-1886 (old rats + NO-1886; 22.8+/-2.8%, P < 0.05 vs. old rats). In contrast, NO-1886 showed no effect on the endothelium-independent relaxation by sodium nitroprusside. These results indicate that NO-1886 improves impaired endothelium-dependent relaxation of rat aorta associated with aging, possibly by correcting lipid metabolism.

Aging↗

PubMed1998

Nitric oxide activates Ca2+-activated K+ channels in cultured bovine adrenal chromaffin cells.

The effects of sodium nitroprusside (SNP) on Ca2+-dependent K+ (KCa) channels in cultured bovine adrenal chromaffin cells were investigated using single channel recording patch-clamp techniques. KCa channels were activated by application of 100 microM SNP to the extracellular side of cell-attached patches. Methylene blue (300 microM), an inhibitor of soluble guanylate cyclase, or H-8 (1 microM), a protein kinase inhibitor with relative specificity for cGMP-dependent protein kinase, diminished but did not completely abolish the SNP-induced KCa channel activation. Diethylamine/NO complex (DEA/NO), an NO donor, also activated KCa channels in cell-attached patches. Furthermore, application of 100 microM SNP or 100 nM DEA/NO to the intracellular surface of excised inside-out patches also activated KCa channels in the bath solution which contained 1 microM Ca2+. These results indicate that SNP is capable of activating the KCa channel via cGMP-dependent and -independent mechanisms. These studies demonstrate that NO may serve as an important regulatory mechanism for catecholamine secretion in chromaffin cells via the activation of KCa channels.

Adrenal Medulla↗

PubMed1998

Does prolonged exercise alter diet-induced thermogenesis?

Diet-induced thermogenesis (DIT) is mainly an insulin-mediated response and the result of fat and glycogen synthesis. We investigated DIT at rest and after exercise to clarify the mechanism of exercise-induced changes in DIT in 6 healthy men (mean age 36 +/- 16 years). Subjects exercised for 1 h at 58% of maximal O2 consumption on a bicycle ergometer and then rested for 8 h sitting in a comfortable chair (exercise experiment). On a different day, subjects rested for 8 h without preceding exercising (non-exercise experiment). At 12.30 h, the subjects were given their second meal. DIT to individual meal did not differ significantly between the exercise and non-exercise days. Increased insulin sensitivity and increased free fatty acid oxidation by exercise may facilitate the conversion of glucose to glycogen in muscle. On the other hand, insulin secretion expressed as the ratio of plasma levels of insulin to glucose after the meal was significantly decreased in the exercise experiment (p < 0.05). Study of heart rate variability showed that sympathetic tone, a primary hormonal determinant of glucose metabolism during exercise, was increased and parasympathetic tone was decreased during the recovery period in the exercise experiment (p < 0.05). These findings suggest that changes in DIT are affected by many factors and may be related to the balance between these counteracting factors.

Adult↗

PubMed1998

Respiratory quotient in patients with non-insulin-dependent diabetes mellitus treated with insulin and oral hypoglycemic agents.

The respiratory quotient (RQ) reflects the amount of energy derived from carbohydrate as apposed to fat metabolism. To assess the metabolic state of patients with non-insulin-dependent diabetes mellitus, the RQ was measured five times a day (at 09.00, 11.00, 13. 00, 14.00, and 17.00 h) in 20 healthy subjects and 60 diabetic patients. Diabetic patients treated with insulin or sulfonylurea showed significantly higher RQ values than normal subjects and nontreated diabetic patients. Diabetic patients without treatment showed higher glucose levels, and their RQ values were significantly lower than those of treated patients. There was a significant inverse correlation between RQ and blood glucose levels at 11.00 h (r = -0.361, p < 0.01) in diabetic patients, but no significant relation with HbA1c. Treated diabetic patients with a higher body mass index tended to show a higher RQ than those with a lower one (r = -0.269, p = 0.083). Within 1 year, 7 of 13 patients, who had RQ > 1.0, gained more than 3 kg, while only 5 of the remaining 32 treated diabetic patients gained more than 3 kg (p < 0.05). This demonstrates that diabetic patients with a higher RQ tended to gain weight despite the use of insulin or oral hypoglycemia agents. The RQ increased by infusing both insulin and glucose in normal subjects. These results suggest that a high RQ results from excess insulin and excess food. The RQ is a good predictor of weight gain in diabetic patients treated with either insulin or oral hypoglycemic agents.

Calorimetry, Indirect↗

PubMed1998

The correlation between coronary stenosis index and flow-mediated dilation of the brachial artery.

We examined the relationship between flow-mediated dilation (FMD) of the brachial artery and the extent and severity of coronary artery disease (CAD). Using high-resolution ultrasonography, we measured FMD and nitroglycerin-induced brachial artery dilation. We studied 121 patients (77 men, 44 women; mean age 64+/-11 years, range 25-79 years) who underwent coronary arteriography. The extent and severity of CAD were assessed by the coronary stenosis index (CSI). The adjusted FMD correlated inversely with CSI (rs=-0.63, p<0.0001). Multivariate analysis demonstrated that the adjusted FMD was an independent predictor of CSI. The adjusted FMD was 10.2+/-4.8% in patients without CAD (n=32), 7.7+/-6.0% in patients with single-vessel disease (n=31), 5.2+/-5.5% in patients with double-vessel disease (n=29), and 2.0+/-3.9% in patients with triple-vessel disease (n=29). The adjusted FMD was significantly lower in the double- (p<0.01) and triple-vessel (p<0.0001) disease groups than in patients without CAD. The adjusted FMD was significantly lower in the triple-vessel disease group than in the single-vessel disease group (p<0.001). Based on our results, as coronary atherosclerosis becomes more severe, the adjusted brachial artery FMD becomes more severely impaired.

Adult↗

PubMed1998

Effect of exercise training and food restriction on endothelium-dependent relaxation in the Otsuka Long-Evans Tokushima Fatty rat, a model of spontaneous NIDDM.

We investigated whether endothelial function may be impaired in the Otsuka Long-Evans Tokushima Fatty (OLETF) rat, a model of spontaneous NIDDM. The effect of exercise training and food restriction on endothelial function was also studied. OLETF rats were divided into three groups at age 16 weeks: sedentary, exercise trained, and food restricted (70% of the food intake of sedentary rats). Otsuka Long-Evans Tokushima rats were used as the age-matched nondiabetic controls. Endothelium-dependent relaxation of the thoracic aorta induced by histamine was significantly attenuated in the sedentary or food-restricted rats, and exercise training improved endothelial function. Relaxation induced by sodium nitroprusside, a donor of nitric oxide, did not differ significantly among groups. Both exercise training and food restriction significantly suppressed plasma levels of glucose and insulin and serum levels of triacylglycerol and cholesterol and reduced the accumulation of abdominal fat. Insulin sensitivity, as measured by the hyperinsulinemic-euglycemic clamp technique, was significantly decreased in sedentary rats but was enhanced in exercise-trained and food-restricted rats. The urinary excretion of nitrite was significantly decreased in sedentary and food-restricted rats compared with nondiabetic rats and was significantly increased in exercise-trained rats. These results indicate that exercise training, but not food restriction, prevents endothelial dysfunction in NIDDM rats, presumably due to the exercise-induced increase in the production of nitric oxide.

Abdomen↗

PubMed1998

[Sixty percent lidocaine tape alleviates pain on injection of propofol after diminishing venipuncture pain].

We evaluated the efficacy of the 60% lidocaine tape in alleviating pain associated with intravenous propofol administration in 71 gynecological patients. Thirty-eight women had the tape applied for 2.5 h before venipuncture, with the remaining patients acting as the control. A 20 gauge cannula was inserted into the cephalic vein. Propofol at room temperature was injected at a rate of 1200 ml.hr-1. The statistical significance of differences was established with the Mann-Whitney's U test and the chi 2 test. The median level of pain intensity resulting from venipuncture among the patients treated with the tape was smaller than that in the control group (16.5, vs 34, P = 0.006). Thereafter, cannulation was successfully achieved with reduced or no pain (VAS at cannulation < or = 25, n = 39), and only 16% of the treatment group complained of pain on injection as compared with 53.8% of the control group (P = 0.02). Moreover, the pain intensity was decreased with lidocaine tape (P = 0.006). The cost of the lidocaine tape is covered by medical insurance for reducing pain on venipuncture. Thus, as the tape also alleviates the pain on injection of propofol through its anesthetic action, it can be a safe, easy and cost-effective method as "it kills two pains with one tape".

Adult↗

PubMed1997

Japanese dietary protein allowance is sufficient for moderate physical exercise in young men.

The sufficiency of the dietary protein allowances recommended by the Ministry of Health and Welfare of Japan for various physical exercises has not been examined. We investigated the protein requirement for moderate-intensity physical exercise using nitrogen balance in the isoenergetic state. Seventeen healthy college students exercised for 10 days with an adaptation period of three days and non-exercise control period of 10 days. They were given a maintenance level of energy and 1.08 g/kg per day of high quality mixed proteins recommended by the Ministry of Health and Welfare of Japan throughout the experimental period. They performed treadmill running during the exercise period at about 65% of VO2max for 25, 41 or 48 min/day, which required 200, 300 or 400 kcal of extra energy, respectively. Although the exercise increased dermal nitrogen loss, urinary nitrogen excretion tended to decrease. Consequently, the exercise ranging from 200 to 400 kcal/day did not significantly alter the nitrogen balance. Thiobarbituric acid-reactive substances and glutathione disulfide were not increased after exercise, suggesting that the moderate exercise, recommended for health promotion by the Ministry of Health and Welfare of Japan, does not cause oxidative damage to healthy subjects. These findings demonstrate that a protein intake of 1.08 g/kg per day is enough for moderate exercise.

Adult↗

PubMed1997

[Combined surgery for coronary artery disease and thoracic aortic disease].

Combined surgery in 6 cases who had coronary artery disease and thoracic aortic disease simultaneously was analyzed. Case # 1 had ascending aortic replacement under deep hypothermic circulatory arrest because of iatrogenic aortic dissection caused by aortic clamp during the routine coronary artery bypass grafting (CABG). Case # 2 had DeBakey type II chronic dissection. Case # 3 had type I aortic dissection 4 years after the initial CABG. Both case # 2 and # 3 had ascending aortic replacement under retrograde cerebral perfusion along with CABG. Transverse aortic replacement was performed in case # 4, # 5 and # 6 under selective cerebral perfusion along with CABG. Case # 4 was associated with ascending-transverse aortic aneurysm. Case # 5 had aortitis syndrome complicated with severe coronary ostial stenosis and cervical branch stenosis. Case # 6 also had aortitis syndrome, severe coronary ostial stenosis, heavily calcified ascending-transverse aorta, and mitral and aortic regurgitation. This case had mitral and aortic valve replacement additionally. Case # 2 died of low cardiac output syndrome and multi-organ failure postoperatively. Case # 4 did not recover from profound shock that followed the preoperative acute myocardial infarction. The problems of low cardiac output syndrome caused by long interval of ischemic cardiac arrest, and also the problems of proximal anastomotic site of saphenous vein grafts were discussed.

Aged↗

PubMed1997

[Postoperative evaluation of presealed vascular prostheses in surgical treatment of the thoracic aorta].

Two kinds of presealed vascular prostheses were started to use for the thoracic aortic surgery at May 1991. The Gelseal graft was implanted in 13 patients and the Hemashield graft in 31 patients. Each cases was performed enhanced computed tomographic scan periodically to determine the extent of postoperative dilatation of both grafts. These showed that the Gelseal graft is significant more dilated than the Hemashield graft (51.2 +/- 8.1% vs 10.2 +/- 5.8%: p < 0.001). The dilatation was almost completed within one month and no addition later on both grafts. Because of more dilatation and possibility of serous discharge, the Gelseal graft is not good prosthesis for the patients who require postoperative anticoagulant therapy. If the Gelseal graft is used, smaller size should be selected for its dilatation. As the result of this study, the Hemashield graft is more suitable for thoracic aortic lesions than the Gelseal graft.

Aged↗

PubMed1997

[A case of ventricular septal perforation treated surgically with an infarction exclusion technique].

We report an 85-year-old woman with postinfarction interventricular septal perforation. She underwent successful emergent surgical treatment by a slightly modified method based on David-Komeda's procedure. Perforation in this case occurred four days after acute myocardial infarction. Preoperative Qp/Qs was 2.58, and pulmonary artery pressure was 34/25 mmHg. The area of infarction was large, and the perforation was the linear type 2.5 cm long near the apex. A probe was not able to pass through the perforation due to its complicated configuration. A double Xenomedica patch was sutured on the left side of the interventricular septum without excising the infarcted area. The suture line was placed on healthy myocardium apart from the infarcted area. The Xenomedica patch was sandwiched between the closure line of the ventriculotomy. Four days after surgery, residual shunt was observed by echocardiogram, but this subsequently disappeared on the 17th postoperative day. The patient was discharged from our hospital on the 57th postoperative day, and is now doing quite well.

Aged↗

PubMed1996

Nonuniformity of the constitutive law parameters for shear rupture and quasistatic nucleation to dynamic rupture: a physical model of earthquake generation processes.

Based on the recent high-resolution laboratory experiments on propagating shear rupture, the constitutive law that governs shear rupture processes is discussed in view of the physical principles and constraints, and a specific constitutive law is proposed for shear rupture. It is demonstrated that nonuniform distributions of the constitutive law parameters on the fault are necessary for creating the nucleation process, which consists of two phases: (i) a stable, quasistatic phase, and (ii) the subsequent accelerating phase. Physical models of the breakdown zone and the nucleation zone are presented for shear rupture in the brittle regime. The constitutive law for shear rupture explicitly includes a scaling parameter Dc that enables one to give a common interpretation to both small scale rupture in the laboratory and large scale rupture as earthquake source in the Earth. Both the breakdown zone size Xc and the nucleation zone size L are prescribed and scaled by Dc, which in turn is prescribed by a characteristic length lambda c representing geometrical irregularities of the fault. The models presented here make it possible to understand the earthquake generation process from nucleation to unstable, dynamic rupture propagation in terms of physics. Since the nucleation process itself is an immediate earthquake precursor, deep understanding of the nucleation process in terms of physics is crucial for the short-term (or immediate) earthquake prediction.

Journal Article↗

PubMed1996

[Surgical results of total replacement of aortic root].

Total aortic root replacement was performed on 19 cases since December 1979 to May 1995. They were devided in two groups. First 7 cases were operated by original Bentall procedure with inclusion technique (group A). Succeeding 12 cases were operated by Carrel patch method or Cabrol procedure without inclusion maneuver. There were 2 operative deaths in group A (28.6%) and was one death in group B (8.3%) respectively. The operation time and the extracorporeal circulation time were significantly shorter in group A than that in group B. Anastomotic leakage was noted in 2 cases of group A. One of them required reoperation and another one with coronary ostial leakage died of congestive heart failure. We concluded that non-inclusion method for aortic root replacement was superior to conventional inclusion technique and reimplantation of both coronary ostia with Carrel patch method was the best tactics especially for Marfan syndrome in terms of long term results.

Adult↗

PubMed1994

[A case report of coronary artery bypass grafting surgery with aprotinin in a patient undergoing chronic haemodialysis].

A 61-year-old patient who was receiving haemodialysis because of chronic renal failure developed unstable angina pectoris with three vessel disease. We performed successful coronary artery bypass grafting, using aprotinin to reduce blood loss. Blood loss during the operation was 750 ml, and during a 6 hour period after the operation it was 150 ml. This amount seemed to be small. No adverse clinical effects attributable to aprotinin were seen, and urine volume and plasma creatinine were not different before and after the operation. In summary, aprotinin is useful adjunct to open heart surgery in chronic haemodialysis patients.

Aprotinin↗