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Biomedical subjects

S Nakaya

Publications and source records attributed to S Nakaya.

At least 73 records · Page 4Linked to original sources
PubMed1982

Subcostal two-dimensional echocardiographic imaging of peripheral right coronary artery in Kawasaki disease.

A new two-dimensional echocardiographic technique was developed to detect peripheral right coronary aneurysms in Kawasaki disease. Because the main stem of the right coronary artery runs along the tricuspid valve ring and the posterior interventricular groove, these regions were examined for coronary aneurysms using the subcostal approach. Of 52 patients with Kawasaki disease, 14 right coronary aneurysms were visualized in eight patients. Most of the coronary aneurysms were elicited as circular or oval echo-free spaces on the right side of the right ventricle or at the area around the tricuspid valve ring. These echocardiographic features coincided well in size, shape and anatomic position with angiographic appearances. The subcostal approach could not image the normal coronary artery. In three patients whose echocardiograms showed no abnormal echo-free space, the angiographic studies proved that the right coronary arteries were intact. These results suggest that this echocardiographic technique is useful for detecting peripheral right coronary aneurysms in patients with Kawasaki disease.

Aneurysm↗
PubMed1982

[Clinical study of membranous ventricular septal defect in infancy and childhood by two-dimensional echocardiography].

A two-dimensional echocardiographic study was performed in patients (pts) with isolated ventricular septal defect (VSD). Group I included 48 pts with membranous VSD (aged from 3 months to 11 years) diagnosed by cardiac catheterization and angiocardiography. In 25 of 27 pts demonstrated a defect only by two-dimensional echocardiography (2DE), mean pulmonary artery pressure (MPAP) was higher than 25 mmHg and 26 of these 27 pts showed a large left to right shunt of more than 30 per cent, and the remaining one pt had Eisenmenger complex. In 15 of 16 pts demonstrated VSD with the pouch formation of the septal leaflet (PSL) by 2DE, MPAP was lower than 25 mmHg. These 16 pts showed various left to right shunt ratios (small to large). In all 4 pts demonstrated VSD with membranous septal aneurysm (MSA) and 1 pt demonstrated no findings by 2DE, MPAP was low (under 25 mmHg) and a left to right shunt was small. Group II included 400 pts with membranous VSD (aged 11 days to 15 years) diagnosed clinically. All 221 pts demonstrated VSD had PSL or MSA. PSL was demonstrated in 261 pts, MSA in 27 pts, both PSL and MSA in 33 pts and no findings in 79 pts by 2DE. Group III included 41 pts with spontaneous closed VSD (aged 3 months to 8 years) diagnosed clinically. PSL was demonstrated in 15 pts, MSA in 11 pts and no findings in 15 pts by 2DE. On the basis of these observation, PSL and MSA may play an important role in spontaneous diminution or closure of membranous VSD, and in most of VSD pts without PSL and MSA pulmonary hypertension is shown and spontaneous diminution of VSD size can not be anticipated. Visualization of PSL and MSA by 2DE may predict the prognosis and is clinically very useful in the management of pts with isolated membranous VSD.

Blood Pressure↗
PubMed1981

The diagnostic accuracy of computed tomography in obstructive biliary disease: a comparative evaluation with direct cholangiography.

Computed tomography (CT) and direct cholangiography were performed in 75 patients for the evaluation of obstructive biliary disease. The two modalities correlated well in cases of moderately or severly dilated intrahepatic bile ducts that showed tortuosity and/or engorgement, but mild dilatation with stretching of theperipheral intrahepatic bile ducts that was seen with direct cholangiography was detected with CT in only one of nine patients. Consequently, the CT diagnosis was correct in 41 of 51 patients (80.4%) with obstructive biliary disease; however, CT was correct in only 15 of the 25 patients (60%) with nontumorous obstructive biliary disease. It is concluded that, in cases of clinically suspected nonneoplastic obstructive disease, percutaneous transhepatic cholangiography or endoscopic retograde cholangiopancreatography should be performed even when dilated ducts are not demonstrated by CT.

Cholangiography↗
PubMed1981

Echocardiographic visualization of ventricular septal defect in infants and assessment of hemodynamic status using a contrast technique. Comparison of M-mode and two-dimensional imaging.

Twenty-seven patients with ventricular septal defect (VSD), ages 2 months to 2 years, were evaluated by both M-mode and two-dimensional echocardiography (2-D echo) with the aid of a peripheral venous contrast technique. M-mode echocardiography was unreliable for imaging VSD. Using 2-D echo, defects in the interventricular septum were visualized in all patients examined; defects in the membranous portion (24 patients) were visualized by the subcostal frontal approach and defects in the supracristal portion (three patients) by the subcostal sagittal approach. The 2-D echo contrast study revealed negative contrast jets appearing through the defect in the right ventricle in 22 patients with a pulmonary-to-systemic blood flow ratio greater than 2.0, and positive contrast jets appearing through the defect in the left ventricle in 13 patients with a right-to-left ventricular peak pressure ratio greater than 0.71. We conclude that 2-D echo with peripheral contrast technique confirmed the anatomic location of VSD and indicated the approximate right-to-left ventricular peak pressure ratio, showing the contrast material shunting through the defect itself.

Cardiac Catheterization↗
PubMed1980

Effects of nucleoside triphosphates on choleragen-activated brain adenylate cyclase.

To investigate the effects of nucleoside triphosphates on the activation of adenylate cyclase by choleragen and on the stability and catalytic function of the choleragen-activated enzyme, we treated samples of particulate preparation from bovine brain successively in three separate incubations with extensive washing between each step. In incubation I, choleragen and NAD were pesent to activte the adenylate cyclase. In incubation II, conditions were varied to assess enzyme stability. Finally, adenylate cyclase activity was assayed with ATP or adenylyl imidodiphosphate [App-(NH)p] as the substrate. Even when assays contained an optimal concentration of GTP, nucleoside triphosphate (plus a regenerating system) was required in incubation I for maximal choleragen activation; in order of effectiveness, GTP > ITP > ATP greater than or equal to CTP = UTP. During incubation II (at 30 degrees C), activity of the choleragen-treated fractions was essentially completely stable when 100 microM GTP (plus a regenerating system) was present. ITP and ATP were less effective. Activation produced by guanylyl imidodiphosphate was more stable than that resulting from choleragen, GTP, and NAD. After activation of membranes with choleragen, NAD, and GTP, nucleoside triphosphate plus a regenerating system (but not NAD or additional choleragen) was essential for expression of maximal activity. In order of effectiveness, GTP > ITP > ATP greater than or equal to CTP = UTP. It appears that GTP, which was effective in micromolar concentrations, plays an important role not only in the activation of adenylate cyclase by choleragen but also in the stabilization and expression of the catalytic function of the activated enzyme.

Adenosine Triphosphate↗
PubMed1980

Subxiphoid cross-sectional echocardiographic imaging of the "goose-neck" deformity in endocardial cushion defect.

The cross-sectional echocardiographic demonstration of the "goose-neck" deformity is described in four patients with endocardial cushion defect. The diagnosis was confirmed in each patient by left ventricular angiocardiogram. The subxiphoid approach of cross-sectional echocardiography in diastole allowed visualization of an elongated, narrowed, and somewhat horizontally inclined configuration of the left ventricular outflow tract, which appeared almost identical to that obtained by angiocardiography. In systole, the right border of the left ventricle was composed of the cleft anterior mitral leaflet, the left-sided line of which was convex toward the left ventricular cavity. The mitral valvular echoes were thickened, jagged and irregular, which seemed to correspond to the scalloped appearance of the right border of the left ventricular silhouette in a systolic phase of the left ventricular angiocardiogram. There were no obvious differences between the goose-neck configuration of complete-type endocardial cushion defect and that of ostium primum atrial septal defect.

Echocardiography↗
PubMed1980

Vasoactive intestinal polypeptide stimulation of cyclic AMP formation in rat central nervous system.

Vasoactive intestinal polypeptide (VIP) stimulated cyclic AMP formation in the anterior pituitary, hypothalamus, pons and cerebral medulla of rat in vitro. The concentration of VIP above 10(-7) M significantly raised cyclic AMP level of these tissues with dose-dependency and the maximum stimulation of cyclic AMP formation was obtained at 5 min incubation. This stimulatory effect of VIP was not inhibited by propranolol or somatostatin. However, no enhancement of hormone release from the anterior pituitary or hypothalamus into the incubation medium by VIP was observed. These results suggest that VIP may act through adenylate cyclase in specific areas of rat central nervous system independent of beta-adrenergic receptor, but it may not necessarily be related to hormone release from the anterior pituitary or hypothalamus.

Animals↗
PubMed1979

Mucocutaneous lymph node syndrome. A cross-sectional echocardiographic diagnosis of coronary aneurysms.

The cross-sectional echocardiographic technique for detecting coronary artery aneurysms of mucocutaneous lymph node syndrome (MLNS) was examined. When cutting the aortic root in round slices by the echocardiographic scanner, each of the right and left coronary arteries was imaged as a linear echo-free structure arising from the aortic root. Of 22 normal subjects, the left main coronary artery was imaged in all, the anterior descending branch in 18, the circumflex branch in six, and the right coronary artery in 18. Of 41 patients with MLNS, coronary artery aneurysms were detected as large echo-free spaces in four patients who were proved later to have these lesions by coronary angiography or autopsy. In addition, in four patients, whose echocardiograms demonstrated the coronary arteries to be normal, the angiographic studies showed that the coronary arteries were intact. These results suggest that the cross-sectional echocardiographic technique is a useful noninvasive diagnostic method for imaging the coronary arteries and the aneurysms in MLNS.

Aneurysm↗
PubMed1978

Effect of bombesin infused intrapancreatically on glucagon and insulin secretion.

Synthetic bombesin was infused at a dose of 20 pmoles/kg/min for 10 min into the cranial pancreaticoduodenal artery of anesthetized dogs. Plasma immunoreactive glucagon concentrations in the cranial pancreaticoduodenal vein as well as in the femoral artery were concurrently and slowly elevated. However, the net release of glucagon from the pancreas did not increase significantly during infusion of bombesin. Plasma immunoreactive insulin concentrations in the pancreatic vein were transiently raised, and a delayed rise was noted in arterial plasma IRI. Net release of insulin was significantly augmented during infusion of the tetradecapeptide. Plasma glucose levels did not change after bombesin. These results indicate that the gastrointestinal tetradecapeptide may stimulate secretion of both insulin and gut glucagonlike immunoreactivity in the dog.

Animals↗
PubMed1976

Comparison of mode of activation of guanosine 3':5'-monophosphate-dependent and adenosine 3':5'-monophosphate-dependent protein kinases from silkworm.

Guanosine 3':5'-monophosphate (cyclic GMP)-dependent protein kinase (protein kinase G) partially purified from silkworm pupae was selectively activated by cyclic GMP at lower concentrations. Nevertheless, the enzyme seemed to differ from adenosine 3':5'-monophosphate-dependent protein kinase (protein kinase A) with respect to the mode of response to cyclic nucleotides. The catalytic activity and cyclic GMP-binding activity were not dissociated by cyclic GMP in a manner similar to that described for protein kinase A. The enzyme was not inhibited by regulatory subunit of protein kinase A nor by protein inhibitor. A sulfhydryl compound such as 2-mercaptoethanol or glutathione was essential for the activation by cyclic GMP, and an extraordinary high concentration of either Mg2+ (100 mM) or Mn2+ (25 mM) was needed for maximal stimulation by cyclic GMP. A polyamine such as spermine, spermidine, or putrescine could substitute partly for the cation. Kinetic analysis indicated that Km for ATP was decreased whereas Ka for cyclic GMP was increased significantly at high concentrations of the cation. The effect of the cation to decrease Km for ATP was not evident in the absence of a sulfhydryl compound. These characteristics of protein kinase G described above were not observed for protein kinase A which was obtained from the same organism.

Animals↗