Biological studies of AT-308. 2. Hypocholesterolemic effect of AT-308, a new derivative of 1,2,4-oxadiazole, in rats.
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Animals↗
Biomedical subjects
K Shimamoto
Publications and source records attributed to K Shimamoto.
Clinical evaluation of newly developed CRT viewing station: CT reading and observer's performance.
The clinical performance of the new viewing station with six CRT monitors (17-inch, 1,024 x 1,280) was evaluated. In the primary interpretation of CT images, time measurements were carried out for eight radiologists. No significant differences in reading time existed between CRT and film in 3 of 4 readers in head CT series, and in 2 of 6 readers in body CT series. Compared with the previous system, the new prototype system achieved an approximately 30% decrease in reading time in both head and body CT studies and could reduce mental and eye fatigue.
Computer Systems↗
Effects of a calcium channel blocker, manidipine, on insulin sensitivity in essential hypertensives.
This study was designed to investigate the effects of the calcium channel blocker manidipine on insulin-dependent glucose uptake (insulin sensitivity) and insulin action to renal sodium handling and pressor systems in essential hypertensive (EHT). Seven EHT were hospitalized and a 2-h euglycemic hyperinsulinemic glucose clamp was performed in a fasting condition before and after 2 weeks administration of manidipine (20 mg/day). Insulin sensitivity was evaluated as M-value calculated from the infusion rate of glucose. Manidipine administration decreased mean blood pressure and increased M-value significantly in EHT. Before the manidipine treatment, hyperinsulinemia during the clamp induced a decrease of urinary sodium excretion and increases of plasma norepinephrine and plasma renin activity in EHT. After manidipine treatment, however, hyperinsulinemia induced natriuresis and did not augment the pressor systems activity. Thus, the calcium channel blocker improved insulin resistance as assessed by glucose clamp technique in EHT. Suppression of augmented renal sodium reabsorption and pressor system activities of insulin may be connected with the hypotensive mechanisms and the natriuresis caused by calcium channel blockers.
Blood Glucose↗
Display method can affect interobserver agreement: comparison of 'zoom-and-pan' and 'browse-and-paste' for primary CT interpretation.
Eight radiologists interpreted body CT images of 30 cases using a viewing station (six 17-in. monitors, 1024x1280). Using two different display methods, 'zoom-and-pan' and 'browse-and-paste', the readers described the presence or absence of liver tumors using a five-point rating scale and temporal changes between the current and previous studies using a seven-point rating scale. There was no significant difference in kappa values for tumor detection between the two display modes. However, in describing temporal changes, the kappa value of the browse-and-paste was significantly lower than that of zoom-and-pan (p<0.01). Browse-and-paste may have the disadvantage of greater interobserver variation.
Data Display↗
Cardiac death prediction and impaired cardiac sympathetic innervation assessed by MIBG in patients with failing and nonfailing hearts.
BACKGROUND: Although cardiac sympathetic nerve dysfunction is related to poor clinical outcome, a critical sympathetic dysfunction level for predicting cardiac death is still unclear. The current study was designed to investigate which indices derived from metaiodobenzylguanidine (MIBG) imaging have prognostic value compared with clinical and cardiac function variables, and to determine the threshold of cardiac MIBG activity for identifying patients likely to suffer cardiac death in both failing and nonfailing hearts. METHODS AND RESULTS: Myocardial I-123-MIBG activity was quantified as a heart-to-mediastinum ratio in 414 consecutive patients, 173 (42%) of whom had symptomatic heart failure. After cardiac function measurements, patients were followed up with an end-point of cardiac or noncardiac death. During a mean follow-up period of 22 months, 37 cardiac deaths occurred: 23 resulted from heart failure, 9 were sudden cardiac deaths, and 5 were fatal myocardial infarctions. Multivariate analysis using the Wald chi2 and the Cox proportional hazard model revealed that late heart-to-mediastinum ratio, the use of nitrates, early heart-to-mediastinum ratio, and left ventricular ejection fraction were independent predictors of cardiac death; late heart-to-mediastinum ratio, New York Heart Association (NYHA) class, the presence of previous myocardial infarction, and age were independent predictors of heart failure and sudden cardiac death. Late heart-to-mediastinum ratio was the most powerful predictor of overall cardiac death among the variables. The Kaplan-Meier analysis showed that a late heart-to-mediastinum ratio of 1.74 or less, age greater than 60 years, the presence of myocardial infarction, and NYHA functional class 3 or 4 strongly indicated poor clinical outcomes. Furthermore, the more powerful incremental prognostic values were obtained by using MIBG imaging in combination with conventional clinical variables. CONCLUSIONS: Impaired cardiac sympathetic innervation assessed by MIBG activity has the greatest potential for predicting cardiac death and may be useful for identifying a threshold level for selecting patients at risk for death by heart failure, sudden cardiac death, and fatal myocardial infarction.
3-Iodobenzylguanidine↗
Two- and three-dimensional assessments of myocardial perfusion and function by using technetium-99m sestamibi gated SPECT with a combination of count- and image-based techniques.
BACKGROUND: Although the myocardial gated single photon emission computed tomography (SPECT) technique makes it possible to assess concurrent myocardial perfusion and function, quantitative methods for analyzing and displaying gated SPECT data in 2- and 3-dimensional presentations for regional and global cardiac assessment have not been established. METHODS AND RESULTS: We have developed an automated quantitative method for assessing perfusion and function by means of technetium-99m sestamibi gated SPECT with a computerized technique combining count-based and image-based methods. We have examined its validity in 91 patients by comparing its results with those of conventional techniques: contrast left ventriculography and radionuclide angiocardiography. In addition to color-scale displays of regional function, simultaneous 3-dimensional presentations of regional wall motion and perfusion have been produced. High reproducibility of gated SPECT analysis with this algorithm was demonstrated; interoperator errors (%CV) were 2.6% to 5.5%, and good intraobserver reproducibility was confirmed by means of high correlation coefficients (0.954 to 0.989). Left ventricular volumes assessed by means of contrast left ventriculography and by means of the gated SPECT technique showed significant correlations (left ventricular end-diastolic volume, y = 1.01x - 9.7, r = 0.845, P<.001, standard errors of the estimate [SEE] = 14 mL; left ventricular end-systolic volume, y = 1.03x - 1.4, r = 0.902, P<.001, SEE = 6 mL). Left ventricular ejection fraction determined by means of gated SPECT with the new algorithm closely correlated with that determined by means of radionuclide ventriculography (y = 1.05x - 0.6, r = 0.891, P<.001, SEE = 3 %). These parameters quantified by means of the present method correlated closely with those derived from the QGS program (r = 0.926 to 0.987). CONCLUSION: In comparison with conventional techniques, myocardial gated SPECT with automated quantitative analysis provides accurate and reproducible data for global and regional function. Quantitative concurrent assessment of myocardial perfusion and function by using 2-and 3-dimensional representations appears to be superior to other modalities and to contribute to nuclear cardiology practice.
Adult↗
CT findings in groove pancreatitis: correlation with histopathological findings.
OBJECTIVE: To clarify the CT characteristics of groove pancreatitis, which is a segmental form of chronic pancreatitis. MATERIALS AND METHODS: The CT findings in four patients with proved groove pancreatitis were reviewed retrospectively. The examinations consisted of plain CT, dynamic CT, and high dose enhancement CT in each patient. Correlation between the CT findings and the resected specimens was performed in three patients. RESULTS: In every patient a mass was detected in the head of the pancreas that involved the duodenum. Dynamic CT demonstrated a poorly enhancing lesion extending between the pancreatic head and the duodenum. Cysts in the duodenal wall and/or the groove and duodenal stenosis due to wall thickening were seen in four and three patients, respectively. These CT findings reflect the histological characteristics of this disease. CONCLUSION: Computed tomography, including dynamic study, can demonstrate the characteristic findings of groove pancreatitis and suggest the diagnosis.
Adult↗
Progressive jaundice due to lymphangiosis carcinomatosa of the liver: CT appearance.
In a case of progressive jaundice, contrast-enhanced CT demonstrated unevenly distributed areas of periportal low attenuation throughout the liver that were demonstrated to be dilated lymphatics with multiple carcinomatous thrombi at postmortem study. This CT appearance may be characteristic of lymphangiosis of the liver.
Adenocarcinoma↗
Role of renal dopaminergic activity on renal sodium-water metabolism in congestive heart failure.
1. The role of the renal dopaminergic system in water-sodium metabolism in heart failure remains unclear. 2. In this study, the urinary free dopamine excretion (uDA), delivery of L-dopa to renal proximal tubules (plasma L-dopa x creatinine clearance (Ccr)), and the production of dopamine in the kidney [uDA/(plasma L-dopa x Ccr)] were investigated in patients with congestive heart failure (n = 30) and in normal controls (n = 12). In both groups, endogenous Ccr, urinary excretion of sodium (UNaV), fractional excretion of sodium (FENa), plasma noradrenaline concentration (pNA) and plasma L-dopa concentration were also estimated. 3. uDA, plasma L-dopa, delivery of L-dopa and dopamine production in the kidney showed successively lower values in congestive heart failure with progression in NYHA functional class. 4. UNaV (r = 0.458, P < 0.05) and Ccr (r = 0.539, P < 0.01) positively correlated with uDA. Linear correlations were found between left ventricular ejection fraction and uDA (r = 0.574, P < 0.01), pNA (r = -0.495, P < 0.01) or plasma L-dopa (r = 0.423, P < 0.05). 5. From these findings, it was suggested that (i) uDA was clearly suppressed in patients with CHF, and (ii) the possible mechanisms of its suppression might be due to decrease of delivery of L-dopa into the proximal tubules and suppressed production of dopamine from L-dopa in the kidney.
Adult↗
Detection of cardiac calcinosis in hemodialysis patients by whole-body scintigraphy with 99m-technetium methylene diphosphonate.
A noninvasive method for the diagnosis of cardiac calcinosis, a life-threatening complication in hemodialysis patients with end-stage renal disease (ESRD), has not, as yet, been firmly established. We tested whether whole body scanning with 99m-technetium methylene diphosphonate (MDP) might visualize cardiac calcinosis. In 19 consecutive chronic hemodialysis ESRD patients (13 males and 6 females, aged 40-81, mean 63 +/- 8 years) with cardiovascular disease [mitral annular calcinosis and/or calcified aortic valve (n = 4), hemodialysis cardiomyopathy (n = 1), coronary artery disease (n = 9) and peripheral artery atherosclerotic disease (n = 6)], MDP uptake in the heart was compared to that in 7 non-ESRD controls with hyperparathyroidism due to adenoma. Cardiac and lung field MDP uptake was confirmed in only 3 (16%) and 5 (26%) of the 19 ESRD subjects, respectively, but was absent in controls. Positive cardiac uptake was related to cardiac calcified complications (mobile intracardiac calcinosis, myocardial calcinosis and mitral annular calcification) and the duration of hemodialysis (p = 0.015). While it was statistically insignificant, subjects showing MDP uptake were elder and had higher serum Ca or Ca x P product and lower intact parathyroid hormone levels. These results suggest that cardiac calcinosis in ESRD patients can be detected noninvasively by myocardial scintigraphy with 99m-technetium MDP.
Adult↗
A case of calcitonin-producing parathyroid adenoma with primary hyperparathyroidism.
A 57-year-old female was admitted to our hospital with general lassitude, loss of appetite, nausea, upper abdominal pain, thirst, polydipsia and polyuria. On admission, she had an asymmetrical pear-shaped tumor in the right supraclavicular region and severe hypercalcemia. Plasma C-PTH was elevated to 22.72ng/ml. Plasma calcitonin was also elevated to 336 pg/ml. She died of respiratory and cardiac failure of two weeks after admission without any positive response to the treatment, including hemodialysis. Pathohistologically, the tumor was a parathyroid adenoma. The concentrations of C-PTH, intact PTH and calcitonin in the tumor tissue were markedly high: 4.56 micrograms/g wet, 13.9 ng/g wet and 50.7 ng/g wet, respectively. Immunohistologically, the tumor cells and the fibrous stroma were stained strongly positive to rabbit anti-human calcitonin antibody and rabbit anti-human N-PTH antibody by indirect immunoperoxidase staining. Calcitonin-producing tumors, except for medullary thyroid carcinoma are rarely reported. To our knowledge, this is the first report of such a calcitonin-producing parathyroid adenoma associated with primary hyperparathyroidism.
Adenoma↗
A case of swallow syncope induced by vagovagal reflex.
A 65-year-old man experienced syncope associated with advanced atrioventricular (AV) block upon swallowing. Continuous electrocardiogram (ECG) monitoring revealed first and second degree AV block. ECG revealed advanced AV block (Max R-R 6.38 s) upon swallowing, a cold drink. Demand ventricular pacing alleviated his symptoms. In this patient, the advanced AV block might have been precipitated by a vagovagal reflex triggered by expansion of the esophagus, resulting in selective suppression of the atrioventricular node.
Aged↗
Breast ultrasonography: diagnostic efficacy of a computer-aided diagnostic system using fuzzy inference.
We have developed a computer-aided diagnostic (CAD) system using fuzzy inference for breast sonography and have evaluated the performance of the system. Our CAD system is not an automated image processing method, but requires the observer's subjective "scoring." Seven radiologists interpreted 54 breast mass lesions (24 malignant, 30 benign). Six criteria (shape, border, halo, internal echoes, posterior echoes, and edge shadows) were scored using a five-point rating scale. The output was described as a real number from 0.0 to 1.0. For cancer diagnosis, the sensitivity of the radiologists, a six-criteria CAD version, and a four-criteria version (excluding posterior echoes and edge shadows) were 63.1%, 82.1%, and 78.0%, respectively. Specificity was 71.0%, 42.9%, and 51.0%, respectively, while accuracy was 67.5%, 60.3%, and 63.0%, respectively. No significant differences in the areas under ROC curve (Az) were found between the observers and CAD system. Several cases assessed as false-negative by observers were correctly diagnosed by the CAD system, and diagnostic efficacy could be improved, especially among novice sonographers. Although the system's high false-positive rate needs to be reduced, it will assist radiologists in generating a level of suspicion for malignancy.
Algorithms↗
Influence of matrix size, vessel shape, vascular diameter, flow velocity, course of vessels on MR angiography.
Basic experiments were done to examine the influence of the extent of curve, direction of flow, vascular diameter, velocity of flow, and course of vessels on MR angiography. In the first experiment, two phantoms were constructed of vinyl tubing, a hairpin type and one with tubes bent to varying degrees. These phantoms were imaged in two matrices, different FOV, and of various velocities with a 1.5 Tesla system. Images of a normal volunteer were also obtained. In studies of the hairpin phantoms, a low intensity artifact appeared at the curve position, and the edge became fuzzy when the flow was perpendicular to the phase encoding direction. These phenomena were more apparent with a smaller matrix, smaller FOV, more gentle angle, larger diameter, and faster flow; in other words the component along the direction was dominant. In the phantom that used bent tubes, another low intensity artifact appeared on the medial side of the outflow portion. The results obtained from the volunteer corresponded well to those from the basic experiments. It was thought that the profile of flow was not well demonstrated due to the coarse matrix. In the second experiment, water flowed at various speeds through three-dimensional phantoms that were made of vinyl tubes of various diameters and directions. The phantoms were imaged with two- and three-dimensional time of flight and phase contrast angiography. The lower limits of detection of the phase contrast method were almost the same. In the coronal plane, the lower limit decreased to 2.5 mm for arteries and 9.5 mm for veins.(ABSTRACT TRUNCATED AT 250 WORDS)
Blood Flow Velocity↗
Ultrasonographic and thermographic evaluation of the lower limb after transfemoral catheterization.
Ten adults undergoing routine transfemoral catheterization were randomly selected for study. Ultrasonography and thermography were performed within 48 hours before and after the catheterization procedure. Sites proximal and distal to puncture were assessed. There were no angiographic procedural complications in any case. Distal to the puncture, Doppler evaluation revealed a decrease in peak systolic velocity (PSV) in six cases, with four showing a greater than 30% fall, while three of the four cases with an increase had a less than 10% rise in PSV. Findings at the proximal site showed no distinct pattern. Changes in the resistive index at both sites were minimal. There was a significant increase in turbulence distal to the site of puncture in six cases. B-mode revealed arterial wall thickening compromising the lumen in half the cases. Thermography was done in four cases, and there was a tendency for an increase in limb temperature after the catheterization procedure. In view of the above-mentioned findings seen in "normal, uncomplicated" procedures, a larger study appears warranted to assess the significance of these findings and to attempt a correlation of the above results with the angiographic procedure.
Adult↗
[Fatty acid metabolic and perfusion abnormalities in hypertrophied myocardium assessed by dual tracer tomography using thallium-201 and iodine-123-beta-methylpentadecanoic acid].
Fatty acid metabolic and perfusion abnormalities associated with cardiac hypertrophy were investigated using dual tracer tomography with thallium and a cardiac metabolic tracer, 15-(p-iodophenyl)-3-R, S-methylpentadecanoic acid (BMIPP), in eight patients with hypertrophic cardiomyopathy (HCM) and in three with hypertension (HT). Thallium and BMIPP uptakes were scored and analyzed in 143 segments (13/heart) by comparison with the left ventricular wall thickness measured by two-dimensional echocardiography. Complete agreement of both scores in HT patients was significantly higher than that in HCM patients (64% vs 24%, p < 0.001), while a lower BMIPP uptake compared to that of thallium (mismatching) was observed more frequently in HCM than in HT patients (65% vs 31%, p < 0.001). The wall thickness significantly (p < 0.005) correlated with BMIPP uptake score. HCM patients showed a low BMIPP uptake in 22 hypertrophic segments (59%) and 15 non-hypertrophic segments (41%), and reduced BMIPP uptake in 29% hypertrophic segments, while HT patients showed just five segments with decreased BMIPP uptake of which 4 were non-hypertrophic and only one hypertrophic. The left ventricular ejection fraction assessed by radionuclide ventriculography was normal and no regional wall motion abnormality was detected in any patient by echocardiographic and scintigraphic studies. Metabolic abnormalities detected by the iodine-123-beta-methyl fatty acid analog in hypertrophic cardiomyopathy may be independent of thallium myocardial perfusion, regional wall motion, or the magnitude of cardiac hypertrophy, suggesting that fatty acid imaging may be useful in investigating the pathogenesis and subclinical abnormality of hypertrophic cardiomyopathy, and differentiation from secondary, induced cardiac hypertrophy.
Adult↗