Biomedical subjects

K Ohzono

Publications and source records attributed to K Ohzono.

60 records · Page 4Linked to original sources

PubMed1988

Minimal osteonecrosis as a segmental infarct within the femoral head.

Minimal osteonecrosis (MON) is a small and eccentrically localized lesion of osteonecrosis (ON) of the femoral head. This form of ON shows clinically benign features, but may be indicative of the pathomechanism of ON. Of 180 patients (275 hips) with ON, 15 patients (19 hips) were found to have MON. Based on the geography of the femoral head, the lesions were grouped into four types: anterior (seven hips), superior (six hips), medial (five hips), and lateral (one hip). When the location of the lesion was compared with the normal vascular anatomy, a close correlation between the location and the segmental blood supply in the femoral head became evident. Histologic findings showed localized infarction of the trabeculae and bone marrow, but no evidence suggesting repeated episodes of infarction, which is an essential feature of typical ON. From these findings, MON may be a segmental infarct within the femoral head. Interruption of the blood flow may possibly occur not in the main trunk but in the terminal branch of the lateral epiphyseal or superior metaphyseal artery; such as ischemic event is probably a single brief attack, leading to this form of infarction in contrast to typical ON developing with prolonged or recurrent obstructions.

Adult↗

PubMed1987

The osteoblastic response to osteoarthritis of the hip. Its influence on the long-term results of arthroplasty.

We have followed up a series of total hip arthroplasties performed for secondary osteoarthritis and analysed the results in relation to the osteoblastic response to the disease. This was assessed pre-operatively from the radiographic appearance, according to Bombelli's criteria (1983). Of 63 hips in 55 patients followed up for five to 13 years, 17 were hypertrophic, 24 normotrophic and 22 atrophic in type. The atrophic-type hips showed a high incidence of acetabular loosening, leading to unsatisfactory clinical results in 32%. By contrast, the hypertrophic-type hips had a low incidence of acetabular loosening, while the normotrophic type showed intermediate results. It was concluded that the osteoblastic response to osteoarthritis is closely related to acetabular loosening and to late clinical failure.

Adult↗

PubMed1986

Transmural distribution of myocardial infarction: difference between the right and left ventricles in a canine model.

The evolution of myocardial infarction 24 hours after ligating both the right coronary artery and the obtuse marginal branch of the left circumflex coronary artery was examined in 33 anesthetized dogs. Postmortem coronary angiography and a tracer microsphere technique were used to determine risk areas and their collateral blood flows, respectively. The mean weight of the risk areas was 11.3 +/- 0.5 g (mean +/- SEM) in the right ventricle and 10.5 +/- 0.9 g in the left ventricle (NS). The weight of infarcted tissue was 5.7 +/- 0.7 g in the right ventricle and 5.2 +/- 0.9 g in the left ventricle (NS). In both ventricles, infarct weight was linearly related to risk area size, and the percent of risk area necrosis was inversely correlated with the extent of collateral flow at 24 hours of coronary ligation, defined as the mean myocardial blood flow inside the central risk area. Ratios of infarct to risk area between the subendocardial and subepicardial layers were 0.76 +/- 0.06 and 0.28 +/- 0.05 in the right and left ventricles, respectively (p less than 0.01, between ventricles, n = 31), which coincided well with subendocardial-to-subepicardial-flow ratios at 24 hours, ie, 0.86 +/- 0.04 in the right ventricle and 0.32 +/- 0.06 in the left ventricle (p less than 0.01). The regional distribution of myocardial infarction correlated well with flow distribution inside the risk area; the slope of these relations was similar between the subendocardium and subepicardium in the right ventricle, whereas in the left ventricle it was larger in the subendocardium than in the subepicardium. Thus, in the dog, the inherent change in the regional distribution of coronary collateral blood flow is an important modifier in the evolution of myocardial infarction, especially in the left ventricle.

Angiography↗

PubMed1986

Wall motion abnormalities in Q wave and non-Q wave myocardial infarction in isolated left anterior descending coronary artery disease.

Although the frequencies of transmural involvements of Q wave and non-Q wave myocardial infarction (MI) are similar, their clinical features are different in many aspects. In the present study, the wall motion abnormalities of 34 patients with Q wave MI and eight patients with non-Q wave MI, all with isolated left anterior descending artery (LAD) lesion, were compared using left ventriculography and two-dimensional echocardiography. This study clearly demonstrated that the severity and distribution of asynergy were significantly greater in patients with Q wave MI than in those with non-Q wave MI. Akinesis or dyskinesis was observed in all 34 patients (100%) (151 of 544 segments) with Q wave MI, and in four of eight patients (50%) (eight of 128 segments) with non-Q wave MI (p less than 0.05). Apical aneurysm occurred exclusively in patients with Q wave MI. In non-Q wave MI, asynergy was localized at the papillary muscle level or the apex. At the chordal level, asynergy was observed in only one of eight cases with non-Q wave MI, and in 24 of 34 cases with Q wave MI (p less than 0.05). These results suggest that the infarct size may be smaller in non-Q wave MI than in Q wave MI in patients with isolated LAD lesion.

Echocardiography↗

PubMed1985

Role of afterload in determining regional right ventricular performance during coronary underperfusion in dogs.

The relationship between coronary perfusion pressure and regional myocardial performance of the right ventricular free wall was studied, in the presence or absence of right ventricular hypertension in 13 open-chest dogs. The right coronary artery was perfused through a shunt from a carotid artery. Regional systolic shortening of the right ventricular free wall was measured by means of a sonomicrometric technique at various levels of coronary perfusion pressure. Regional shortening was insensitive to coronary perfusion pressure or flow when it was above 31 mm Hg or 0.27 ml/min per g. Once coronary perfusion was below this critical level, regional shortening in both base to apex and circumferential orientations decreased linearly, depending on the degree of perfusion pressure. Despite the presence of a monoexponential relationship between coronary perfusion pressure or flow and regional shortening, a direct linear relation between perfusion pressure and flow was consistently noted, with or without pulmonary artery banding, suggesting that there is limited autoregulation of right coronary flow. The critical perfusion pressure for maintaining regional myocardial function of the right ventricle was highly dependent on the level of right ventricular systolic pressure (r = 0.64 - 0.72, P less than 0.05). Thus, right ventricular systolic pressure was one of the important determinants of regional wall motion during coronary underperfusion.

Animals↗

PubMed1979

Electron microscopical studies on the genesis of white adipocytes: differentiation of immature pericytes into adipocytes in transplanted preadipose tissue.

In order to clarify the relationships between perivascular cells, capillaries and fat cells, with a special reference to the origin of fat cells, we have made a light and electron microscopical study on the developing epididymal adipose tissue of newborn to 5-week-old rats, and also on the differentiating, transplanted epididymal preadipose tissue from 6-day-old rats. Development of epididymal preadipose tissue progressed rapidly 6 or 7 days after birth. The preadipose tissue on the 5th day after transplantation consisted of differentiated areas with many mature fat cells, and of undifferentiated areas in which these cells were scanty. In the differentiated areas of developing epididymal preadipose tissue, both in situ and transplanted, many fat cells seemed to develop in the area immediately adjacent to growing capillaries, but cells intermediate between perivascular cells and preadipocytes were seldom observed. However, in undifferentiated areas of transplanted tissue, we found ultrastructural evidence that immature pericytes of capillaries can differentiate into preadipocytes.

Adipose Tissue↗