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Biomedical subjects

Y Nimura

Publications and source records attributed to Y Nimura.

At least 127 records · Page 7Linked to original sources
PubMed1987

Mechanism of mitral regurgitation in patients with myocardial infarction: a study using real-time two-dimensional Doppler flow imaging and echocardiography.

The aim of the present study was to elucidate the mechanisms of mitral regurgitation accompanying myocardial infarction. Severity and site of mitral regurgitation was evaluated by the real-time two-dimensional Doppler flow imaging technique in 81 patients with old myocardial infarction. The incidence of mitral regurgitation did not depend on the region of infarction. There was, however, a close relationship between the site of regurgitation and the region of infarction. In patients with mitral regurgitation spurting from the posteromedial area of the valve, the inferior wall was involved in infarction without exception and in some of these patients, the posteromedial papillary muscle was also found to be affected by myocardial infarction; in those with regurgitation spurting from the anterolateral area, the anterior wall showed asynergy. On the other hand in patients with mitral regurgitation spurting from the central area, the region of infarction varied. In these patients, however, the larger the diameter of the mitral anulus, the more severe the grade of regurgitation. The extent of asynergy was another factor related to the severity of mitral regurgitation. Both longitudinally and transversely, broad infarction leads to the enlargement of the mitral anulus. However, even if the mitral anulus is not so dilated, severe involvement of either commissural area results in severe mitral regurgitation from the same commissural side. Thus, there are two major causative factors of mitral regurgitation: (1) asynergy of the papillary muscle or the ventricle that results in mitral regurgitation located in the commissural area of the same side as asynergy, and (2) enlargement of mitral anulus, which results in regurgitation from the central area of the orifice.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Characterization of histamine H1-receptor on rat hepatocytes.

The binding sites for [3H]pyrilamine in isolated rat hepatocytes were characterized. Scatchard analysis revealed two kinds of binding sites in hepatocytes, a high-affinity site and a low-affinity one. The rates of binding of the radioligand with the high-affinity binding site and its dissociation were rapid. The specificity of the sites for various histamine antagonists indicated that the high-affinity [3H]pyrilamine binding site is representative of the histamine H1 receptor. Treatment of hepatocytes with protease or phospholipase A2 significantly decreased the maximum binding capacity of the high-affinity site without affecting its dissociation constant, suggesting that the binding site is proteinaceous and is sensitive to a change in the lipid moiety of the membrane. Hepatocytic cyclic AMP and cyclic GMP were not significantly modulated by incubating hepatocytes with histamine. Thus, the action of histamine on hepatocytes might not be mediated by the cyclic nucleotides.

Animals↗
PubMed1987

[Non-invasive assessment of the peak pressure gradient between the aorta and pulmonary artery in patent ductus arteriosus].

The validity of continuous wave Doppler ultrasound estimation of the peak pressure gradient between the aorta (Ao) and pulmonary artery (PA) in patients with patent ductus arteriosus (PDA) was evaluated. Ten patients, all without other anomalies, underwent cardiac catheterization and cine-angiography, and the peak pressure gradient between the Ao and PA (dP(C)) was measured during catheterization. In all cases the mean PA pressure was less than 35 mmHg. According to the angiographic findings, the patients were categorized as Group A, consisting of seven patients whose features of the ductus were wedge- or tube-like in configuration; Group B, consisting of two patients whose features were termed "orifice-like" stenosis including one with abrupt narrowing on the PA side of the ductus and the other with a short segmental ductus. Group C consisted of one patient who had a long curved segmental ductus. The maximum velocity of ductus flow was measured by continuous wave Doppler ultrasonography, and the estimated peak pressure gradient between the Ao and PA by Doppler (dP(D] was calculated using the simplified Bernoulli equation (dP = 4V2). In group A, dP(D) was overestimated compared to dP(C) in all patients by 19 to 51 mmHg (mean 34 mmHg). However, in group B, the difference between dP(D) and dP(C) was small, 5 mmHg and 7 mmHg, respectively. In group C, dP(D) was underestimated as opposed to dP(C). Thus, in the limited cases, the simplified Bernoulli equation could be used in estimating the peak pressure gradient between the Ao and PA. However, this equation leads to overestimation in many cases.(ABSTRACT TRUNCATED AT 250 WORDS)

Aorta↗
PubMed1987

[The physiological role of the pericardium: studies based on right heart inflow dynamics in cases of left-sided pericardial defect].

Using pulsed Doppler echocardiography, the effects of postural change on the blood flow pattern in the superior vena cava and in the right ventricular inflow tract were investigated to evaluate the physiological role of the pericardium. Eight cases of left-sided pericardial defect and eight healthy subjects were examined. 1. Suppressed inflow into the right atrium during systole in left-sided pericardial defect was manifested as a reduction of the systolic wave (S) in the superior caval vein and impairment of the systolic shift of the tricuspid annulus. This suppression suggested unsatisfactory volume expansion in the right atrium due to the absence of negative intrapericardial pressure. 2. In left-sided pericardial defect, the right ventricular inflow pattern differed from the normal, most distinctly in the right lateral recumbent position, though the cardiac motion was nearly identical with that of the normal in this position. In this position, the ratio of the peak velocity of presystolic filling to that of rapid filling was increased, and the deceleration half time of rapid filling was prolonged. These findings indicated that the right ventricular rapid filling was retarded, and was compensated by the filling due to atrial contraction. It is assumed that right ventricular filling is influenced by hydrostatic pressure due to changes in posture in the absence of restriction by the pericardium. 3. It is concluded that the pericardium maintains negative intrapericardial pressure, so that each cardiac chamber is uniformly expanded for its filling, and that this function minimizes the influence of posture on cardiac hemodynamics.

Adult↗
PubMed1987

[Noninvasive measurement of cardiac output using two-dimensional Doppler echocardiography and analysis of sources of error].

The purpose of this study was (1) to analyze the factors responsible for errors in the two-dimensional Doppler echographic measurements of cardiac output (C.O.) and (2) to establish a noninvasive method for measuring C.O. The subjects were 50 cardiac patients who had neither aortic valve disease nor intracardiac shunts. The C.O. was calculated using the following formula: C.O. (l/min) = mean flow velocity (cm/sec) x pi(aortic ring diameter/2)2 (cm2) x 60/10(3) Left ventricular ejection flow velocity was recorded in the center of the aortic ring from the apical approach. Mean velocity was calculated by integration of instantaneous mean velocity in the ejection phase divided by the cardiac cycle length, and was corrected by the Doppler incident angle. The inner diameter of the aortic ring was measured in the parasternal long-axis view at the time of the maximum ejection flow velocity. The following results were obtained: 1. Sources of error in the measurement of cardiac output. 1) Accuracy of instantaneous mean velocity calculating circuit: This calculating circuit was accurate in model experiments using pulsatile flow. 2) Effect of high-pass filter: In model circuits, application of high-pass filter overestimated flow velocity. The higher the cut-off frequency of the high-pass filter, the larger the overestimation. This was probably due to the parabolic flow velocity profile in the circuit. 3) Flow velocity profile in the aortic ring: The flow velocity profile seemed to be flat in the aortic ring except near the anterior aortic wall. Therefore, the effect of the high-pass filter was considered to be negligible in case of clinical application. 4) The effects of shift and size of sample volume: The location of sample volume relative to the aortic valve ring shifted about 7 mm during systole. However, the shift and size of sample volume seemed to have little effect on the measured C.O., because the flow velocity profile was nearly flat in the aortic ring. 5) Ultrasound beam incident angle: From a practical viewpoint, it was necessary to set an incident angle of less than 50 degrees for minimizing the error. We were able to set the angle within 50 degrees in all but one of patients. 6) Diameter of the aortic ring: Two-dimensional echographic measurement of the aortic ring diameter was not so accurate; it seemed to become a major source of error in the calculation of C.O.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1987

[Optimum time for surgical intervention in pure mitral regurgitation: serial echocardiographic evaluations].

To determine the optimum time for surgical intervention in pure mitral regurgitation, 39 patients were studied by echocardiography before and after surgery. Pure mitral regurgitation included mitral valve prolapse with or without ruptured chordae tendineae. Twenty-two patients had mitral valve replacement and 17 had mitral valve reconstruction. Serial echocardiograms were obtained from all 39 patients (average follow-up: 40 months). Two of the 39 patients died suddenly at home on 26 and 62 months after surgery. One of the 39 patients now suffers from congestive heart failure. These three patients had preoperative left ventricular end-diastolic dimensions greater than 70 mm and left ventricular end-systolic dimension greater than 50 mm. Operation is recommended for patients with end-diastolic dimension less than 70 mm and end-systolic dimension less than 50 mm.

Echocardiography↗
PubMed1987

[Relationship of two-dimensional echocardiographic mitral valve prolapse to mitral regurgitation assessed by color Doppler flow imaging].

Although two-dimensional echocardiography is a standard for diagnosing mitral valve prolapse, the diagnostic criteria are controversial. Regardless of valve ballooning we have used our criteria which are based on the dislocation of the mitral valve coaptation. The purpose of this study was to clarify the relationship between the location and the degree of mitral valve prolapse assessed by two-dimensional echocardiography and those of mitral regurgitation evaluated by color Doppler flow imaging, which enables us detailed analysis of regurgitation. Twenty-three patients with idiopathic mitral valve prolapse diagnosed by our criteria were studied. They were 14 men and nine women, ranging in age from 19 to 72 years (mean 44.7). In any patients, prolapse of either the anterior or posterior leaflet does not satisfy the Gilbert's criteria. Twenty of the 23 patients had mitral regurgitation by color Doppler flow imaging, and the grade was II, III or IV in 16 of these 20 patients. In 19 of 20 patients, the localization of the regurgitant jet flow from the mitral orifice coincided with the two-dimensional echocardiographic site of dislocation of mitral valve coaptation. Therefore, it was concluded that the dislocation of mitral leaflet coaptation detected by two-dimensional echocardiography is an abnormal finding regardless of the protrusion of the valve beyond the mitral ring.

Adult↗
PubMed1987

[Papillary muscle infarction: echocardiographic features and genetic factors].

To study the pathogenesis of papillary muscle infarction, its echocardiographic features were examined in 60 patients with old inferior infarction. Sixty-three healthy elderly persons served as the controls. 1. The papillary muscles were echocardiographically classified as fingerlike and non-fingerlike in configuration whose frequencies were 43% and 57%, respectively. In healthy subjects, the papillary muscles were less echogenic than the left ventricular wall. 2. In five patients, the posteromedial papillary muscle exhibited enhanced echo intensity and no contraction. The papillary muscles in two of these five patients were histologically examined and the diagnosis of papillary muscle infarction was verified. In these five patients, the papillary muscles were echocardiographically classified as fingerlike, and left ventricular infarction was observed to involve the attachment of the posteromedial papillary muscle. All five patients had mitral valve prolapse; posterior in four and anterior in one. Inferior infarction extended to the region just beneath the mitral annulus in the former four patients, but not in the latter one. 3. The echocardiographic features of papillary muscle infarction consisted of enhanced echo intensity of the papillary muscle and mitral valve prolapse, especially that of the posterior leaflet at the posteromedial commissural side, and extension of the asynergy region to the attachment portion of the papillary muscle. The fingerlike morphology of the papillary muscle and involvement of the attachment within the infarcted region are predispositions to the development of papillary muscle infarction.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

[Effect of brain death on hemodynamics and cardiac function: an experimental study].

An experimental model was designed to study hemodynamic and left ventricular functional changes in the course of and after brain death in 13 mongrel dogs. Brain death was induced by creating intracranial hypertension by inflating a balloon inserted into the subdural space. Hemodynamic parameters and left ventricular systolic function as assessed by echocardiography were measured before and during intracranial hypertension and 30 min and 1, 2, 3, 5 and 8 hrs after brain death. During intracranial hypertension, heart rate, systemic and pulmonary blood pressures, cardiac output and systemic vascular resistance raised significantly. After brain death, all parameters decreased rapidly and significantly, and then stabilized. On comparison with values obtained before intracranial hypertension, systemic blood pressure decreased markedly following brain death, while no marked change was noted in cardiac output. This result is attributable to a marked reduction in peripheral vascular resistance following the induction of intracranial hypertension. The left ventricular end-diastolic and end-systolic diameters did not change; consequently, fractional shortening did not change, either. The Weissler's index improved after brain death, reflecting a marked reduction in systemic vascular resistance. This indicates limited usefulness of afterload-dependent cardiac indices. At the agonal period of brain death, three of 13 dogs died because of ventricular fibrillation or a marked decline in systemic blood pressure. Within five to eight hours after brain death, seven dogs died because of intractable acidosis. These results represent the specific hemodynamic features occurring after brain death. It is thought that recognition of these features is useful in managing cases of brain death and in selecting donors for heart transplants.

Animals↗
PubMed1987

Predominance of prostaglandin D2 and I2 in the rat gastric mucosa--analysis by high-performance liquid chromatography.

We have developed a method for measuring prostaglandins (PGs) in rat gastric mucosa by high-performance liquid chromatography (HPLC). The levels of PGD2 and 6-keto-PGF1 alpha, a degradation product of PGI2, were five times higher than those of PGE2 and PGF2 alpha. Oral administration of indomethacin (6 mg/kg body weight) completely abolished the synthesis of all detectable PGs uniformly. These results suggest that endogenous PGs, especially PGD2 and I2, play some roles in the function of the gastric mucosa.

6-Ketoprostaglandin F1 alpha↗
PubMed1987

[A case of polypoid carcinoma of the left hepatic duct].

A case of polypoid carcinoma of the left hepatic duct in 50-year-old male was reported. Extended left hepatic lobectomy with total caudate lobectomy and resection of the right hepatic duct were performed because the tumor involved the right hepatic duct and bile duct branches of caudate lobe, medial and lateral segment. Papillary growth of the tumor was diagnosed definitely by percutaneous transhepatic cholangioscopy (PTCS) and computed tomography. The tumor infiltrated the liver parenchyma of medial segment and compressed the middle hepatic vein. These findings were revealed by selective middle hepatic venography preoperatively.

Adenocarcinoma↗
PubMed1987

[Anatomical studies on the biliary tree of the caudate lobe using an endoscopic retrograde cholangiogram].

The purpose of this study is to clarify positional relationship between the bile duct of the caudate lobe and the bile duct of the hepatic hilum through endoscopic retrograde cholangiogram (ERC). Until December 1984 all 100 ERC that met the following three conditions were studied which at Yachio Hospital. 1. The first cholangiogram. 2. Without obstructive jaundice. 3. No existence of lesion at the hepatic hilum. Bile duct of the caudate lobe were classified into 4 separate types: 1) Ducts from the cranialis of the right caudate lobe which pass via the inferior vena cava to the hepatic hilum named Blr, were confirmed in 32. 2) Ducts from the cranialis of the left caudate lobe to the hepatic hilum named Bl l s, were confirmed in 19. 3) Ducts from the left lateral part of the left caudate lobe to the hepatic hilum named Bl l i were confirmed in 37. 4) Ducts from the caudate process to the hepatic hilum named Blc, were confirmed in 5. One or more of the above bile ducts were confirmed in 53 cases. All four of the above were confirmed in only 2 cases out of 53 cases. Three were confirmed in 7 out of 53 cases, two were confirmed in 20 cases out of 53 cases and one was confirmed in 24 out of 53 cases. Studies for the bile duct of the caudate lobe have been conducted anatomically, but there has been no research by clinical examination.(ABSTRACT TRUNCATED AT 250 WORDS)

Bile Ducts, Intrahepatic↗
PubMed1986

Paradoxical elevations of plasma glucagon levels in patients after pancreatectomy or gastrectomy.

In twenty-five patients undergoing total pancreatectomy (TP), twenty distal gastrectomy (DG) and twenty healthy subjects, effects of oral glucose loading on the plasma glucagon (IRG) levels were determined. Plasma IRG levels were elevated after glucose loading in the TP and DG patients, but not in the healthy subjects. To clarify events related to the elevations in IRG, the plasma IRG components were analyzed by gel filtration in 6 of the TP patients, 5 of the DG patients and 4 of the controls. In the TP group, IRG3500 was not detectable either in the basal state or after glucose loading, while IRG9000 was markedly increased after glucose (p less than 0.002). In the DG group, IRG3500 was significantly suppressed after glucose (p less than 0.05), but IRG9000 was clearly increased (p less than 0.005). In the controls, IRG3500 was suppressed after glucose (p less than 0.05), however, IRG9000 was not detected throughout the examination. Thus, in patients with TP or DG, the essential cause of the high responses of plasma glucagon after oral glucose loading was the increase in IRG9000. Because the food passage route is much the same in TP and DG patients, the IRG9000 elevations are probably related to secretion in the digestive tract.

Adult↗
PubMed1986

Semiquantitative grading of severity of mitral regurgitation by real-time two-dimensional Doppler flow imaging technique.

An attempt was made to determine whether mitral regurgitation could be detected and its severity evaluated semiquantitatively by newly developed real-time two-dimensional Doppler flow imaging in 109 patients who underwent left ventriculography. In the Doppler flow imaging technique, Doppler signals due to blood flow in the cardiac chambers are processed using a high speed autocorrelation technique, so that the direction, velocity and turbulence of the intracardiac blood flow are displayed in the color-coded mode on the monochrome B-mode echocardiogram in real time. Mitral regurgitant flow was imaged as a jet spurting out from the mitral valve orifice into the left atrial cavity. It was noted that the regurgitant jet in the left atrial cavity had a variety of orientations and dynamic features when studied by the present technique. The sensitivity of the technique in the detection of mitral regurgitation was 86% as compared with that of left ventriculography. Mitral regurgitation in the false negative cases was mostly mild. On the basis of the farthest distance reached by the regurgitant flow signal from the mitral valve orifice, the severity of regurgitation was graded on a four point scale and these results were compared with those of angiography. A significant correlation (r = 0.87) was found between Doppler imaging and angiography in the evaluation of the severity of mitral regurgitation. A similar result was obtained for the evaluation based on the area covered by the regurgitant signals in the left atrial cavity. Thus, noninvasive semiquantitative evaluation by real-time two-dimensional Doppler flow imaging appears to be a promising clinical technique.

Adolescent↗
PubMed1986

Diagnosis of mitral valve perforation by real-time two-dimensional Doppler flow imaging technique.

It has been difficult to diagnose mitral regurgitation due to valve perforation using either noninvasive or invasive methods, differentiating it from that resulting from incomplete coaptation of the mitral valve. This report describes three patients with infective endocarditis and mitral valve perforation, which was definitively diagnosed by the real-time two-dimensional Doppler flow imaging technique. In these three patients, B-mode echocardiography demonstrated an echo interruption on the anterior mitral leaflet. However, it was not certain whether this interruption was simply an echo dropout or indicated an interruption of the valve tissue. Doppler flow imaging then demonstrated unusual flow in the vicinity of the echo interruption, which appeared to flow from the left ventricular cavity into the left atrial cavity across the midportion of the anterior mitral valve leaflet during systole and in the opposite direction during diastole. This was interpreted as mitral valve perforation. In general, Doppler flow imaging may play a complementary role with B-mode echocardiography in cardiac diagnosis.

Adult↗
PubMed1986

Right atrial flow topography in healthy subjects studied with real-time two-dimensional Doppler flow imaging technique.

The pattern of normal blood flow in the right atrial cavity was studied using the newly developed real-time two-dimensional Doppler flow imaging technique as a standard reference for the Doppler diagnosis of heart diseases with intracardiac shunts at the atrial level. The study was performed primarily with use of the apical four chamber and the parasternal right ventricular inflow tract views in 21 healthy subjects. The following patterns were observed: blood from the inferior vena cava flowed up along the posterior wall of the right atrium and joined with blood from the superior vena cava in the posterocranial part of the right atrial cavity; the flow then coursed along the roof of the right atrium toward the tricuspid valve in the atrial relaxation phase. This flow was always noted along the interatrial septum in the four chamber view. During and after mid-systole of the right ventricle, additional blood flow away from the tricuspid valve appeared, moving from the valve to the central part of the right atrial cavity, that is, at the lower right of the preceding inflow; this flow was interpreted as arising from eddy currents caused by the preceding inflow. In early diastole of the right ventricle, the flow signal area along the interatrial septum and the roof of the right atrium extended into the right ventricular cavity through the tricuspid valve. In the atrial contraction phase only the blood near the tricuspid valve in the right atrial cavity appeared to flow into the right ventricular cavity. Inflow from the coronary sinus was almost undetectable.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1986

Glycosphingolipid composition of a renal cell line (MDCK) and its ouabain-resistant mutant.

Glycosphingolipids were isolated from a canine kidney cell line (MDCK) and its ouabain-resistant mutant (MDCK-OR) by solvent extraction, mild alkaline methanolysis, a DEAE-Sephadex column, and preparative TLC. The glycolipids were characterized by their mobilities on TLC, an analysis of carbohydrates as trimethylsilyl methyl glycosides and acetates of partially methylated alditols, as well as by treatment with specific glycosidases. In the neutral glycolipid fraction of both cell lines, galactosylceramide (GalCer), glucosylceramide (GlcCer), lactosylceramide (LacCer), digalactosylceramide (Ga2Cer), globotriaosylceramide (Gb3Cer), globoside (Gb4Cer), and the Forssman antigen (IV3GalNAc alpha-Gb4Cer) were identified. The contents of Ga2Cer (4.4 nmol/mg protein), Gb3Cer (0.6), Gb4Cer (2.9), and IV3GalNac alpha-Gb4Cer (19.5) in MDCK-OR were 1.4- to 2.1-fold higher than those in MDCK, while the concentrations of GlcCer (5.3) and LacCer (1.4) in MDCK-OR were about half of those in MDCK. Among acidic glycolipids of MDCK-OR, galactosyl sulfatide (GalCer-I3-sulfate) and lactosyl sulfatide (LacCer-II3-sulfate) were increased to 1.9 (2.7-fold) and 0.2 nmol/mg protein (2.0-fold), respectively, as compared to MDCK. However, N-acetylneuraminosyllactosylceramide (GM3), the predominant ganglioside in both cell lines, was decreased to about one third of the level (1.5 nmol/mg protein) in the parent MDCK (4.7 nmol/mg protein). The fatty acid of the glycolipids in both cell lines consisted mainly of saturated acids of 16, 18, 22, and 24 carbons.

Animals↗