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Biomedical subjects

N Ohshima

Publications and source records attributed to N Ohshima.

At least 73 records · Page 4Linked to original sources
PubMed1991

[Interposition graft technique for the treatment of AAE (annuloaortic ectasia) with aortic regurgitation: surgical results].

Interposition graft technique had been used exclusively in 8 consecutive patients with AAE and AR. Two patients with severely dilated left ventricle (CTR 65, 80%, LVDd 93, 83 mm, LVDs 86, 68 mm), and 1 patient complicated with the postoperative mediastinitis died in the perioperative period, 10, 145 and 135 days after surgery, respectively. In the remaining 5 patients, excellent clinical improvement was observed with the reduction of CTR and echo-cardiographic findings without formation of hematoma, pseudoaneurysm, and leak from the suture lines on DSA and CT.

Adult↗
PubMed1990

Inhibitory effects of mold oil including gamma-linolenate on platelet thrombus formation in mesenteric microvessels of the rat.

Diet including mold oil from a lipid accumulative fungus, containing gamma-linolenic acid, showed an inhibitory effect on thrombus formation in the microvessels of rats by the light/dye method of the authors. Male Wistar rats were fed for 3 to 4 weeks with two series of experimental diets and were examined for thrombus formation. The thrombus formation times to totally occlude, ts, were 347 sec for (mold + soybean)-oil and 236 sec for (palm + soybean)-oil in the first series of diets and 1288 sec for mold oil, 538 sec for olive oil and 575 sec for safflower oil in the second series of diets. Fatty acid composition of plasma, erythrocyte and liver lipids showed an increase in arachidonate content with the diet including the mold oil. Higher arachidonate content seem favorable in inhibiting thrombus formation with increasing PGI2 formation. In terms of the level of lipid hydroperoxides, indicated as a desaturation index of constituent fatty acids, the higher desaturation index with safflower oil gave shorter ts, which suggested some oxygen derived free radicals from polyunsaturated fatty acids were involved in the mechanism of thrombogenesis study by this method.

Animals↗
PubMed1990

Application of the micropipette technique to the measurement of cultured porcine aortic endothelial cell viscoelastic properties.

The viscoelastic deformation of porcine aortic endothelial cells grown under static culture conditions was measured using the micropipette technique. Experiments were conducted both for control cells (mechanically or trypsin detached from the substrate) and for cells in which cytoskeletal elements were disrupted by cytochalasin B or colchicine. The time course of the aspirated length into the pipette was measured after applying a stepwise increase in aspiration pressure. To analyze the data, a standard linear viscoelastic half-space model of the endothelial cell was used. The aspirated length was expressed as an exponential function of time. The actin microfilaments were found to be the major cytoskeletal component determining the viscoelastic response of endothelial cells grown in static culture.

Animals↗
PubMed1990

Effect of wall shear rate on thrombogenesis in microvessels of the rat mesentery.

The role of hemodynamics on platelet thrombus formation was studied in venules and arterioles of the rat mesentery. Thrombus formation was induced by the fluorescent dye/light method for examination of the following factors: 1) the effect of wall shear rate on thrombus initiation, 2) the effect of wall shear rate on the growth of thrombi, and 3) the relation between platelet thrombus initiation and intraluminal velocity profile. The range of wall shear rate was up to approximately 1,000 1/sec in venules and from 640 to 2,900 1/sec in arterioles. Platelet thrombus initiation occurred more rapidly at higher wall shear rate in venules and at lower wall shear rate in arterioles. Thrombus initiation time was shortest around a wall shear rate of 900 1/sec in venules and around 700 1/sec in arterioles. Thrombus growth rate in venules was greatest at a wall shear rate of 1,500-2,000 1/sec. Thrombus initiation and its relation to blood flow was also examined in branched and curved microvessels. In these vessels platelet thrombi were also first initiated at the sites of higher wall shear rate in venules and of lower wall shear rate in arterioles.

Animals↗
PubMed1990

[Reconstruction of radicular arteries in the total replacement of thoracoabdominal aorta].

A technique of reconstructing low intercostal, high lumbar arteries and Adamkiewicz artery is described to prevent paraplegia following operations on the thoracoabdominal aorta. A graft with a side branch is anastomosed proximally and a side branch to the distal thoracic aorta after reinforcement of the stumps under the partial bypass. Applying a clamp on the main graft, flow through the side branch and true lumen of the aneurysm is reestablished and bypass is terminated. The main graft, extended with a Y-graft, is anastomosed to common iliac arteries after proximal suture-ligation to perfuse the lower extremities. Splanchnic arteries are reconstructed according to DeBakey's technique which is followed by trimming of the thoracoabdominal aorta incising longitudinally with a clamp applied on the 1st side branch. Edges of the trimmed aneurysm are sutured to the slit of the graft from the right common iliac artery reconstructing intercostal, lumbar arteries and Adamkiewicz artery from the level of L2 upwards to T4 or more. As a final step, the graft is sutured to the 1st side branch allowing perfusion distally to the right lower extremity and the main graft to the splanchnic arteries and left lower extremity after division of a Y-graft right branch. The technique minimizes ischemic time for reconstruction of the aortic branches and enables complete reconstruction of the radicular arteries.

Aorta, Abdominal↗
PubMed1990

[Familial cardiac myxoma with multiple and contralateral recurrence].

This report described a familial recurrent cardiac myxoma involving mother and daughter. The mother, at 27 year of age, had developed recurrent multiple myxomas in both left and right atrium and right ventricle 4 years after surgical excision of left atrial myxoma. Excision was successful and remains well without signs of recurrence 9 years postoperatively. In an asymptomatic 13-year-old daughter, a recurrent left atrial myxoma was found 3 years after the excision of right atrial myxoma by echocardiographic follow-up at 6 month intervals. Excision of left atrial myxoma was performed and histology showed the essentially the same findings as primary myxoma without signs of malignancy. From an experience of this familial recurrent myxoma and a review of 38 cases of 17 familial cardiac myxoma, it is recommended that wide excision of tumor including surrounding tissues, thorough search for multiple heterotopic tumors at surgery, close postoperative echocardiographic follow-up for at least 5 years, and examination of skin and breast tumor, and endocrine disorder for "complex" myxoma.

Adolescent↗
PubMed1990

[Significance of raphe in congenitally bicuspid aortic valve].

The decrease of rheumatic aortic regurgitation (AR) is observed due to the relative increase of non-rheumatic aortic valvular diseases since 1980. Among 240 patients who had undergone aortic valve replacement (AVR) including combined valvular diseases up to March 1989, the congenitally bicuspid aortic valve was responsible for AR and stenosis (AS) in 33 patients (13.8%) and were divided according to the presence of a raphe. In the raphe (+) group (n = 15), infective endocarditis (IE) (n = 5), prolapse of the aortic valve, mainly non-coronary cusp (n = 5), and thickening with contraction of cusp (n = 4) were the cause of AR. Calcification of the cusp was seen in 2 older (greater than 59 yrs) patients. In the raphe (-) group (n = 18), IE (n = 2), contraction of cusps (n = 2) in the relatively younger (less than 48 yrs) were the cause of AR. Rest of the patients exhibited severe AS due to the calcification of cusps except a case who showed IE with AR in the calcified cusp. Although not generally recognized, the bicuspid valve with a raphe, less tendency to deposit calcium, is an important cause of pure AR severe enough to warrant AVR. The bicuspid valve without raphe, as already recognized, prones to develop severe calcification and AS in later life.

Adult↗
PubMed1989

Effects of exercise training on biochemical and biomechanical properties of rat aorta.

The authors studied the effect of prolonged physical exercise on the mechanical properties of rat aorta in relation to the amounts and qualities of arterial connective tissue fibrous proteins. Twelve male rats were divided into two groups: 6 sedentary rats (S) and 6 training rats (T), which were forced to swim from nine weeks to twenty-five weeks of age. The ultimate tensile stress and the ultimate tensile extension ratio of ring specimens at the descending thoracic aorta were larger in T than in S (192.3 +/- 47.9 g/mm2, mean +/- SD, vs 147.8 +/- 26.0, p less than 0.05; 3.52 +/- 0.13 vs 3.18 +/- 0.27, p less than 0.05; respectively). The elasticity parameter, calculated by fitting stress-strain curves to exponential function in the stress level of 0-20 g/mm2, was lower in T than in S (1.79 +/- 0.15 vs 2.13 +/- 0.24, p less than 0.01). The contents of elastin (alkali-insoluble elastin preparation) and collagen were higher in T than in S (0.44 +/- 0.11 g/g dry aorta vs 0.30 +/- 0.06, p less than 0.05; 0.15 +/- 0.04 g/g dry aorta vs 0.11 +/- 0.04, NS, respectively). Although the aortic calcium content did not significantly change in the training rats (T 1.17 +/- 0.23 mg/g dry aorta, S 0.95 +/- 0.34), the content of calcium in elastin was lower in T than in S (1.75 +/- 0.51 mg/g dry elastin vs 2.63 +/- 1.00, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMed1989

Sex difference of the metabolic disposition of clioquinol in rats.

The order of plasma levels of clioquinol and its conjugates in male rats after intraduodenal administration of 32.7 mumol/kg dose of clioquinol was clioquinol sulfate (C-Sul) greater than glucuronide (C-Glu) much greater than clioquinol, whereas that in female rats was C-Glu greater than C-Sul much greater than clioquinol. Total (urine + bile) recovery was almost the same among male and female rats. The percentage of excretion amounts of C-Sul (urine + bile) to the total excretion amounts for 24 h in male rats after intravenous administration of clioquinol was about twice that in female rats, while the percentage of excretion amounts of C-Glu to the total excretion amounts in male rats was smaller than that in female rats. In intravenous administration of 16.4 mumol/kg dose of C-Glu, C-Sul and clioquinol other than C-Glu were found in bile and urine of male and female rats. The percentage of excretion amounts of C-Sul and C-Glu (urine + bile) to the total excretion amounts was similar among male and female rats, respectively. In intravenous administration of 16.4 mumol/kg dose of C-Sul, C-Glu and clioquinol other than C-Sul were found in bile and urine of male and female rats, and the percentage of excretion amounts of C-Sul (urine + bile) to the total excretion amounts in male rats was 1.3 fold that in female rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Value of vectorcardiography in predicting progress in dilated cardiomyopathy.

Sixteen of 75 patients with dilated cardiomyopathy (DCM) died during a mean follow-up period of 39.7 months. In non-survivors, the cardiothoracic ratio and the left ventricular end-diastolic dimensions were greater, the left ventricular end-diastolic pressures were more elevated, and the cardiac index was lower than in the survivors at the time of initial diagnosis. There were no significant differences between survivors and non-survivors in the magnitude of the maximum QRS and T vectors or in the maximum T angle. In the non-survivors, the maximum QRS vector was directed more posteriorly and the width/length ratio of the loop in the horizontal plane was smaller than in survivors. The QRS loop in the horizontal plane was often distorted in non-survivors or showed a bizarre figure-of-eight configuration. It appears that in DCM a marked posterior displacement of a QRS loop that is narrow and distorted or is in a bizarre figure-of-eight configuration in the horizontal plane indicates an unfavorable prognosis.

Adult↗
PubMed1989

[Simplified operative technique for thoracoabdominal dissecting aneurysm].

A graft with branches is used to reconstruct the extensively dissected thoracoabdominal aorta. Anastomoses of the proximal end of the main graft distal to the left subclavian artery and the side branch to the distal aneurysmal descending thoracic aorta were first undertaken after the preparation of both ends under the iliac vein-artery partial bypass. A main graft with a Y graft extension was anastomosed distally to iliac arteries. This permits the blood flow within the aneurysm and the main graft to the extremities until splanchnic and spinal cord arteries have individually been transferred to the main graft. Ischemic time of the splanchnic and spinal cord arteries, using this technique, can be minimized within 10 minutes to each in the total replacement of descending thoracic and abdominal aorta.

Adult↗
PubMed1989

[Interposition graft method in the treatment of aortic regurgitation associated with aneurysm of the ascending aorta].

Interposition graft method, total replacement of the ascending aorta with a valved conduit and reimplantation of the coronary artery by an interposed graft with some modifications, had been exclusively used for the treatment of aortic regurgitation associated with an aneurysm of the ascending aorta in consecutive 7 cases. Clinical improvement is apparent and postoperative angiographic study revealed a satisfactory coronary and aortic appearance with no leakage, pseudoaneurysm formation nor compression of the graft. This technique proved to be a reliable and safe method for the treatment of aortic regurgitation associated with an aneurysm of the ascending aorta with no mortality nor modality.

Adult↗
PubMed1988

Role of red blood cells in the coronary microcirculation during cold blood cardioplegia.

The role of red blood cells during cold blood cardioplegia was studied using an intravital microscope in 13 isolated canine hearts perfused with diluted blood containing potassium chloride. The coronary microcirculation on the left ventricular epicardial surface was observed while the perfusate temperature was varied between 37 degrees C and 10 degrees C. Considerable sludging of red blood cells occurred during hypothermia. The percentage of capillaries perfused by red blood cells (percentage change) significantly decreased as perfusate temperature was reduced (100, 56, and 31% at 37, 20, and 10 degrees C respectively). This was caused by occlusion of microvessels due to sludging and by functional closure due to hypothermia. There was incomplete recovery of perfusion of capillaries at the end of rewarming (60%). The diameters of venules were reduced to 76% of control value at 10 degrees C because of the decrease in the numbers of feeding capillaries, but this value returned to 91% at the end of rewarming. Coronary vascular resistance (mmHg.ml-1.min-1 (kPa.s.litre-1] significantly decreased from 2.0(0.2) at 37 degrees C to 1.2(0.12) at 10 degrees C, but it increased to 2.4(0.24) at the end of rewarming. The finding in this study that sludging occurred which was slow to clear is a definite disadvantage of perfusion with red blood cells during hypothermia.

Animals↗
PubMed1988

Changes in lipid peroxide concentrations in plasma and tissues by repeated administration of clioquinol to neonatal rats.

The changes in lipid peroxide concentrations in plasma and tissues after subcutaneous administration of clioquinol to clioquinol-sensitive (S-rats) and -resistant neonatal rats (R-rats) were investigated. When a fixed dose of 150 mg/kg/d of clioquinol was given to R-rats for 14 d after birth, no significant difference in lipid peroxide concentrations in plasma, liver, kidney, brain and spinal cord at 5, 10 and 15 d was observed between clioquinol-treated and untreated rats. However, with increasing doses of clioquinol to R-rats every 5 d (150----300----600 mg/kg/d), the lipid peroxide concentrations at 15 d were higher in plasma, brain and spinal cord of clioquinol-treated rats than in those of untreated rats. These results suggested that repeated administrations of large doses of clioquinol to rats increased the lipid peroxides in nerve tissues. With S-rats at 5 d after birth, the lipid peroxide concentrations in liver were approximately twice those in R-rats regardless of the clioquinol administration.

Animals↗
PubMed1988

Velocity profiles of blood flow in microvessels measured by ten channels' dual-sensor method.

Ten channels' dual-sensor method newly developed was applied to the measurement of velocity profiles in arterioles and venules in the rat mesentery. In some experiments, red blood cells (RBC), labelled in vitro with a fluorescein isothiocyanate (FITC), were injected to compare the velocity profiles obtained by the RBC visualization technique with those measured by the dual-sensor method. It was found that the velocity profile of the FITC labelled RBC in straight microvessels was blunt as compared to a parabola. The centerline velocity measured by the dual-sensor method was smaller than that of the FITC labelled RBC by about 20%. The velocity profiles were also measured at the curved arterioles and venules as well as at the bifurcation and the confluence. It was found that the velocities were higher along the inner wall at the curved portion and along the outer wall at the bifurcation of arterioles.

Animals↗
PubMed1988

Microhemodynamics of blood flow in narrow glass capillaries of 9 to 20 micrometers; the Fahraeus effect.

Velocities of the red blood cell (RBC) and the suspending medium in glass capillaries of 9 to 20 micron were measured under microscopic observation. The effects of physical factors such as driving pressure, capillary diameter, hematocrits and RBC deformability on flow velocities were studied using freshly drawn blood of the rat resuspended in phosphate buffered saline solution in the hematocrit range between 5 and 12.5%. These RBC suspensions were made to flow through the test glass capillaries under known negative driving pressures. Ratios of capillary hematocrit to feed hematocrit taken as measures of the Fahraeus effect showed almost constant value of about 0.74. While, ratios of capillary hematocrit to discharge hematocrit showed a characteristic dependence on capillary diameter, showing minimal values at about 13 micron in capillary diameter. The same hematocrit ratios were found to be well correlated with values of wall shear rates estimated from the relative RBC velocities.

Animals↗