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Biomedical subjects

S Nagata

Publications and source records attributed to S Nagata.

At least 649 records · Page 36Linked to original sources
PubMed1986

Primary failure of Hancock porcine bioprosthetic valves: two dimensional echocardiographic assessment.

To reveal the process of primary failure of the Hancock porcine bioprosthetic heart valve, a real-time two-dimensional echocardiography was undertaken. There were 75 cases (84 valves) with 26 in the aortic valve position, 39 in the mitral valve position, 9 in both the aortic and mitral valve positions, and 1 in the tricuspid valve position. The subjects comprised 35 males and 40 females, whose ages ranged from 18 to 65 years with a mean of 44.7 years. Valvular changes such as thickened valve cusps or abnormal valve movement were observed in 27 (32%) of the 84 valves; more specifically, in 5 (14.3%) of the 35 aortic valves and in 22 (45.8%) of the 48 mitral valves, indicating that valvular changes occurred most frequently in the mitral valve position (p less than 0.01). In the period between valve replacement surgery and the appearance of valvular changes, no significant difference was noted between aortic and mitral valve bioprostheses. The duration ranged from 14.5 to 74.5 months with a mean of 50.2 months. Valvular changes were evident in more than 50% of the valve bioprostheses implanted 6 or more years ago. In the mitral valve position, valve cusp changes appeared more frequently at the anterior cusp than at the inner and outer cusps. The frequency was 17 cases at the anterior cusp, 6 at the inner and 9 at the outer. In 7 of the 11 cases followed up after the appearance of valvular changes, an increase in the changes was recognized 7.5 to 29.5 months (a mean of 16.4 months) later.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1986

Platelet dysfunction and alteration of prostaglandin metabolism after chronic alcohol consumption.

To study the effects of chronic alcohol consumption on platelet functions, the rate of arachidonate-induced platelet aggregation, the production of malondialdehyde in platelets, and plasma levels of prostaglandin endoperoxide metabolites were examined in 88 chronic alcoholics and 24 healthy controls. The rate of platelet aggregation and the production of malondialdehyde in platelets were greater in chronic alcoholics both on admission and 1 week after. However, these alterations returned to the level of healthy controls within 4 weeks of abstinence from alcohol and were independent of the number of circulating platelets. Furthermore, on admission, plasma levels of thromboxane B2 were significantly increased in chronic alcoholics when compared with those of healthy controls (400.8 +/- 36.5 versus 241.7 +/- 28.9 pg/ml plasma; p less than 0.025) and were also significantly correlated with malondialdehyde production in washed platelet debris (r = 0.6049; p less than 0.001). In contrast, plasma levels of 6-keto prostaglandin F1 alpha and prostaglandin E were not altered after chronic alcohol consumption. As a result, the ratio of 6-keto prostaglandin F1 alpha to thromboxane B2 was markedly decreased in chronic alcoholics (0.31 +/- 0.03 versus 0.62 +/- 0.13; p less than 0.001). These results strongly suggest that the imbalance in prostaglandin endoperoxide metabolites is produced by chronic alcohol ingestion. Moreover, a significant correlation was observed between platelet aggregation rate and malondialdehyde production during platelet aggregation (r = 0.559; p less than 0.005). Thus, we conclude that chronic alcohol consumption alters platelet thromboxane metabolism, which is likely associated with the increased ability of platelets to aggregate.

Adult↗
PubMed1986

[Bacterial and clinical studies on imipenem/cilastatin sodium in urological infection].

Antibacterial activities of imipenem (MK-0787), cefazolin (CEZ), cefmenoxime (CMX) and cefoperazone (CPZ) were measured by using an agar dilution method against 243 strains of bacteria isolated from the patients with urinary tract infections. The MIC80 of MK-0787 against S. epidermidis, E. faecalis, E. coli, K. pneumoniae, E. cloacae, S. marcescens, P. mirabilis, P. vulgaris and P. aeruginosa was less than or equal to 0.10, 3.13, less than or equal to 0.10, 0.20, 0.78, 1.56, 3.13, 3.13 and 6.25 micrograms/ml, respectively. MK-0787 was more active than CEZ, CMX and CPZ against all bacterial species except Proteus spp. Imipenem/cilastatin sodium (MK-0787/MK-0791) 500 mg/500 mg two times a day for 5 days was given to 31 cases of chronic complicated urinary tract infections and a case of acute prostatitis. Overall clinical effectiveness rate judged by the criteria proposed by the Japanese UTI committee in 22 cases of chronic complicated urinary tract infection treated with MK-0787/MK-0791 was evaluated to be 86% including excellent in 6 cases, moderate in 13 cases and poor in 3 cases. As side effects, 2 cases encountered eruption or anorexia. Abnormal laboratory findings were observed in 6 cases.

Adult↗
PubMed1986

[Two-dimensional echocardiographic diagnosis of mitral valve prolapse].

In recent years, echocardiography has become the standard method of diagnosing mitral valve prolapse. There is a few criteria of diagnosing mitral valve prolapse with two-dimensional echocardiography. In general, the definition of mitral valve prolapse with two-dimensional echocardiography is the motion of a bodily part of the anterior or posterior mitral leaflet superior to the annulus during systole. However, the patients with characteristic phonocardiographic findings of mitral valve prolapse were overlooked by the currently used criteria. I proposed, therefore, an essentially different two-dimensional echocardiographic criterion of diagnosing mitral valve prolapse. The criterion included the systolic dislocation of the anterior and posterior mitral leaflets at the coaptation zone in the parasternal long-axis view. This diagnostic criterion enabled us to obtain a systematic view of the mitral valve abnormality. Quantitation of mitral valve prolapse is necessary to evaluate the severity of the mitral regurgitation and the degree of mitral valve lesion. The grade of severity of mitral valve prolapse was assessed by measuring the distance of dislocation between the anterior and posterior leaflets at the area of coaptation. Analyzed data using this method showed that the degree and extent of mitral valve prolapse increased with age.

Echocardiography↗
PubMed1986

[Progressive left ventricular dilatation in a child with hypertrophic cardiomyopathy: a case report].

Clinical pictures of a patient with progression from hypertrophic cardiomyopathy to dilated cardiomyopathy features in the end stage was described. Echocardiography performed at the age of five years revealed septal hypertrophy without systolic anterior motion (SAM). At 7 years of age, it revealed ventricular septal thickness of 18 mm, left ventricular posterior wall thickness of 24 mm, and marked SAM. Echocardiography at 14 years of age revealed left ventricular dilatation (52 mm in diastole) with poor contraction. Ventricular septal thickness was 18 mm and left ventricular posterior wall thickness was 16 mm. The SAM was no longer present. At autopsy, the heart weighed 590 g, and there was moderate dilatation of the right and left ventricular cavities. Histologically, there were massive fibrosis and myocardial disarray in the right and left ventricular walls.

Cardiomyopathy, Dilated↗
PubMed1986

[Asymmetric septal hypertrophy of sporadic form with abnormal thallium perfusion and myocardial enzymes].

Asymmetric septal hypertrophy with abnormal thallium scintigram and elevated cardiac enzymes were observed in five patients and were studied with special reference to the clinical significance of their clinicopathological features. They were not familial cardiomyopathy patients. Two of the five patients (Cases 1 and 2) exhibited the clinical features characteristic of hypertrophic cardiomyopathy without abnormal thallium perfusion and serum cardiac enzyme levels. A right endomyocardial biopsy for Case 1 disclosed myocardial fibrosis in addition to hypertrophy and disarray of myocardial fibers. The left ventricular cavities of two other patients (Cases 4 and 5) tended to be dilated with signs of impaired systolic function and asymmetric septal hypertrophy. A regional area of reduced thickness was observed in the medial portion of the left ventricular posterior wall of Case 4. The remaining case (Case 3) exhibited left ventricular dilatation and reduced left ventricular systolic function, disproportionate hypertrophy, and had clinical signs of congestive heart failure. Necropsy disclosed massive fibrosis and diffuse disarray of myocardial fibers. Some patients with familial hypertrophic cardiomyopathy progress to exhibit clinical features of dilated cardiomyopathy in the terminal stages, and have massive fibrosis of the myocardium histologically. Thallium scintigraphic abnormalities and elevated serum levels of cardiac enzymes, especially the LDH1 isoenzyme, in patients with hypertrophic cardiomyopathy may be a meaningful indicator of such progression in its early stages. The five patients in the present study exhibited a variety of clinical and histological features which may comprise a spectrum of clinical conditions during the progression from hypertrophic cardiomyopathy to a condition like dilated cardiomyopathy, similar to that in familial patients. This progression and the factors promoting it should be studied further in the near future.

Adult↗
PubMed1986

[Pericardial defect: roles of the pericardium on kinetoanatomic changes of the heart influenced by patients' postures].

To elucidate the physioanatomic roles of the pericardium, the alterations in gross anatomy and cardiac motion induced by posture were examined by two-dimensional echocardiography in seven patients with total absence of the left pericardium. Ten healthy subjects were served as controls. The heart was located deeper within the chest at end-diastole in patients with pericardial defect than in healthy subjects, especially in the left lateral decubitus position. With progression of systole, the cardiac apex swung anteriorly with the cardiac base as the fulcrum, and the heart approximated the normal position at end-systole. The deeper the position of the center of the cross-section of the left ventricular cavity at end-diastole, the more exaggerated the swinging motion in systole. The deep location of the heart in end-diastole is considered to result from release from pericardial support, and the systolic tonus of the cardiac muscle restores the apex to nearly normal position. The characteristic swinging motion of the heart and its alterations dependent of posture seemed the signs suggestive of total absence of the pericardium. The shape of the short-axis view of the left ventricular cavity was nearly circular throughout the cardiac cycle. Therefore, paradoxical motion of the ventricular septum observed on M-mode echocardiography in pericardial defect results from the anterior shift of the entire heart overcoming the proper motion of the interventricular septum. The left ventricular dimension become enlarged according to the postural change from the right to left lateral decubitus positions regardless of the presence or absence of the pericardium. The right ventricular cavity became enlarged in the left lateral decubitus position in patients with pericardial defect. The elevation of hydrostatic pressure due to postural change was considered excessive due to the absence of the pericardium. In the left lateral decubitus position, systolic excursions of the mitral and tricuspid rings became more prominent in healthy subjects, whereas these excursions, particularly of the tricuspid ring, were reduced in patients with pericardial defect. Depressed tricuspid ring motion was also observed in the right lateral position in cases with pericardial defects. The reduced excursion of the tricuspid, ring and the right ventricular dilatation may affect systemic venous return to the right atrium.

Adult↗
PubMed1985

A cell surface marker of thymus-dependent lymphocytes in Xenopus laevis is identifiable by mouse monoclonal antibody.

A mouse monoclonal antibody (mAb), named XT-1 (IgG2b,lambda), was prepared against J strain Xenopus laevis thymocytes. The determinant recognized by this mAb (XT-1 determinant) was expressed by 92-98% thymocytes and 22-37% splenic lymphocytes from intact J strain frogs and larvae, as analyzed by flow cytofluorometry. The XT-1 determinant was also expressed by 20-30% peripheral blood lymphocytes and 5-11% bone marrow lymphocytes from adult, and 11-17% liver lymphocytes from larval J strain Xenopus. Early larval thymectomy depleted XT-1-positive cells in the spleen to less than 2% of the total lymphocyte population. Double immunofluorescence experiments revealed that XT-1+ lymphocytes in the spleen are surface IgM-. The strain distribution study on the expression of XT-1 determinant suggests the allelic polymorphism of the XT-1 determinant. The surface antigen identified by the present XT-1 mAb may provide an important marker for lymphocytes in thymus-dependent lineage in Xenopus.

Animals↗
PubMed1985

Method of tying up hair during hair transplantation.

We have reported on a simple and secure method of tying up hair during transplantation surgery for alopecia. The implements used were Kocher's forceps and rubber bands which are readily obtainable in the operating theater.

Adult↗
PubMed1985

Thallium perfusion and cardiac enzyme abnormalities in patients with familial hypertrophic cardiomyopathy.

Twelve patients of five families with familial hypertrophic cardiomyopathy were examined. Within each family, the older patients showed dilation or diminished contraction of the left ventricle by echocardiography or angiocardiography more frequently than did younger patients. LDH1 fraction (lactic dehydrogenase isoenzyme) and MB-CPK (creatinine phosphokinase isoenzyme) were increased in 7 of 10 patients. Thallium-201 myocardial scintigraphy showed perfusion defect or hypoperfusion in 9 of 10 patient. Eleven cases demonstrated remarkable hypertrophy at the macroscopic level. Marked fibrosis was observed in all 5 of the 11 patients whose histologic findings were obtained. In two necropsy cases, disarray was found throughout the right and left ventricles and the pattern of fibrosis was massive. These findings were different from those of ordinary hypertrophic cardiomyopathy. It is possible that each patient with familial hypertrophic cardiomyopathy may develop more prominent thallium and enzyme abnormalities as he becomes older, regardless of whether he develops a dilated cardiomyopathy picture.

Adolescent↗
PubMed1985

Three autopsy cases of progression to left ventricular dilatation in patients with hypertrophic cardiomyopathy.

The hearts of three cases of congestive heart failure with dilated left ventricles developing in patients with symptomatic hypertrophic cardiomyopathy (HCM) were morphologically investigated. The results showed that disproportionate hypertrophy and dilatation of the left ventricles, accompanied by massive fibrosis and myocardial disarray, were present in the three patients. The mean percent area of fibrosis of the left ventricle was 34.7% and 47.4% at the upper third and lower third levels, respectively, and was much more frequently associated with disarray (84.4 +/- 12.3%). Moreover, the fibrosis was most extensive in the lateral wall of the left ventricle, followed by the posterior, anterior, and interventricular walls. The fibrosis was also diffuse regardless of the subendocardial or subepicardial region of the heart. The findings in the present study suggest that the disarray in this particular series of HCM might be responsible for the mechanism of the fibrosis leading to dilatation of the left ventricle.

Adolescent↗
PubMed1985

Doppler echocardiographic features of ventricular septal rupture in myocardial infarction.

Doppler echocardiography was used to evaluate the features of interventricular septal rupture in six patients with acute myocardial infarction and to substantiate the hemodynamic data and morphologic findings at surgery or autopsy. Although echocardiographic visualization of the septal rupture was obtained in only two of the six patients, unusual Doppler flow signals were detected in the apical portion of the right ventricle in all six patients. Five patients had unusual flow signals during both systole and diastole; one had such signals only during systole. The location of these unusual flow signals coincided with the site of septal rupture confirmed at surgery or autopsy. The pattern of the flow signals in one cardiac cycle was very similar to that of the pressure difference between the left and right ventricular cavities. These findings indicate that the unusual flow signals represent the left to right shunt flows resulting from septal rupture. In conclusion, Doppler echocardiography may be a very useful tool for diagnosing interventricular septal rupture easily and noninvasively in patients with acute myocardial infarction.

Aged↗
PubMed1985

Smoke-like echo in the left atrial cavity in mitral valve disease: its features and significance.

In some patients with mitral stenosis, a smoke-like echo is observed in the left atrial cavity. The present study in 116 consecutive patients with rheumatic mitral valve disease investigated the echocardiographic features and clinical significance of this echo. The smoke-like echo is characterized by the following echocardiographic features: 1) it is composed of numerous microechoes; 2) it curls up slowly in the enlarged left atrial cavity; and 3) it vanishes as soon as it pours into the ventricular cavity. Hemostasis in the left atrial cavity was considered to be an important underlying condition for development of the echo. Hemorheologic conditions indicated that the shear rate of blood flow in the left atrial cavity was calculated to be low enough for the development of red blood cell aggregation. These conditions suggest that the source of the smoke-like echo might be aggregated cells due to hemostasis in the left atrial cavity. Left atrial thrombi were detected in many patients who had this echo in the left atrial cavity. Although it has not been conclusively determined that the presence of the smoke-like echo is a necessary condition for thrombus formation, this echo appears to be closely related to thrombus formation in the left atrial cavity. It is concluded that the presence of this echo indicates severe left atrial hemostasis and is a warning for thrombus formation.

Adult↗
PubMed1985

Inverted-U parascapular flap for the treatment of axillary burn scar contracture.

In this paper we report the technique of using an inverted-U parascapular flap for treating axillary scar contracture. The advantages of using this inverted-U flap are that it is possible to close the donor site by primary suturing, it is possible to cover a large skin defect, and it is possible to construct either a cavity or a swelling in the skin-defect region.

Burns↗