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Biomedical subjects

T Kozuka

Publications and source records attributed to T Kozuka.

At least 235 records · Page 13Linked to original sources
PubMed1987

Quantitative assessment of thallium myocardial washout rate: importance of peak heart rate and lung thallium uptake in defining normal values.

Traditionally, the results of exercise thallium scintigraphy were interpreted by transient defect analysis using initial and delayed images. Recently, washout rate analysis has been used for the relative quantification of exercise thallium scintigraphy. A diffuse slow washout from all myocardial regions has been defined as the indicator of extensive coronary artery disease. However, slow washout has occasionally been observed in normal cases and in healthy myocardial segments which are not supplied by a stenosed artery in patients with single or double vessel disease. We evaluate the factors influencing washout rate in 100 normal patients and 63 patients with angina pectoris (33 cases of single vessel disease and 30 cases of double vessel disease). The washout rates were calculated using circumferential profile analysis. In normal patients, washout rate was closely related to peak heart rate (r = 0.72) and inversely related to lung thallium uptake (r = -0.56). A diffuse slow washout was observed in seven (7%) of 100 normal patients, six (18%) of 33 cases of single vessel disease and eight (24%) of 30 cases of double vessel disease. The patients with diffuse slow washout showed significantly higher lung thallium uptake values and lower peak heart rates than those without diffuse slow washout (P less than 0.01). Thus, this false positive slow washout should be considered in the interpretation of quantitative exercise thallium scintigraphy.

Adult↗
PubMed1987

Clinical significance of 201Tl reverse redistribution in patients with aorto-coronary bypass surgery.

Detection of myocardial ischemia by the stress thallium scan has traditionally been performed using transient defect analysis on exercise, followed by redistribution studies. Worsening of the 201Tl myocardial image from exercise to redistribution is referred to as reverse redistribution. In this study, we found reverse redistribution in 10 (21%) of 48 angina pectoris patients who had undergone aortocoronary bypass surgery. The clinical significance of this phenomenon in these patients was investigated in relation to angiographic and surgical findings. Reverse redistribution was found to occur in regions which were supplied by bypass grafts. These areas showed increased coronary blood flow and rapid thallium washout. Our results indicate that a perfusion defect in the bypass region of the redistribution image might be caused by relatively rapid washout in the bypass graft region compared to the adjacent normal myocardium. These results should be considered in the clinical interpretation of stress thallium scans.

Adult↗
PubMed1987

Cor pulmonale due to embolization of metastatic chondrosarcoma.

A 25-year-old woman with acute dyspnea was found to have nodular shadows in a chest X-ray film. Multiple defects in a perfusion scan indicated pulmonary embolization. The cause of acute cor pulmonale was extensive metastatic embolization from chondrosarcoma of the calf. Embolization by metastasis as a rare occurrence resulting in acute cor pulmonale should be considered in patients with a malignant tumor.

Adult↗
PubMed1987

Identification of cardiac rejection with magnetic resonance imaging in heterotopic heart transplantation model.

It is important to evaluate the severity and extent of cardiac rejection in heart transplantations. Eight heterotopic heart transplantations using mongrel dogs were performed, and grated magnetic resonance imaging (MRI) of the donor hearts was carried out. High signal intensity was obtained in the rejected myocardium at the time of cardiac rejection, especially from the right ventricular wall to the intraventricular septal wall compared with the left ventricular posterolateral wall. In addition, MRI was performed in the excised heart. High signal intensity was also observed in the same region of the excised donor hearts. The histopathological rejection scores were well in agreement with prolonged T1 and T2 relaxation times; severe and mild rejection of the myocardium were distinguished by the T1 and T2 relaxation times. Our results suggest that MRI is able to visualize the transplanted myocardium undergoing rejection and that the right ventricular wall is more sensitive to cardiac rejection than the left. MRI may allow noninvasive evaluation of the severity and extent of cardiac rejection.

Animals↗
PubMed1987

Cardiac transplantation in dogs: evaluation with gated MRI and Gd-DTPA contrast enhancement.

It is important to evaluate the severity and extent of cardiac rejection in heart transplantation. Six heterotopic heart transplantation models in the peritoneal cavity were prepared with 12 adult mongrel dogs and in vivo imaging of the donor heart was performed using gated magnetic resonance imaging, (MRI) and Gd-DTPA contrast enhancement. In cardiac rejection, high signal intensity was obtained in the rejected myocardium, especially from the right ventricular wall to the intraventricular septal wall. The rejected myocardium was clearly visualized after administration of Gd-DTPA (0.5 mmol/kg body weight) via the femoral vein in all donor hearts. The mean ratios of signal intensity calculated from the rejected and normal myocardium were also increased from 25% to 42% after administration of Gd-DTPA. On the other hand, in the cases with no rejection, whole myocardium was visualized homogeneously before and after Gd-DTPA and there was no high signal intensity. Thus, our method has the potential of assessing the extent and severity of cardiac rejection using gated MRI and Gd-DTPA contrast enhancement.

Animals↗
PubMed1987

Variation in coronary arterial dimension (distensible abnormality) after disappearing aneurysm in Kawasaki disease.

Distensible abnormality of the coronary arteries was evaluated in children with Kawasaki disease. The internal diameter of the left coronary artery (diameter) was measured by cineangiography. Among 38 children with Kawasaki disease, 17 developed aneurysms which later disappeared (disappearance group) and 21 had no aneurysm (no aneurysm group). Eleven children had no history of the disease (control group). The maximal diameter was recognized in systole and the minimal diameter in diastole. The mean distensibility index ([maximal diameter-minimal diameter]/minimal diameter) was 5.7% in the disappearance group, 7.9% in the no aneurysm group, and 11.3% in the control group. There were significant differences among the three groups. We demonstrated that distensibility in the coronary arteries in children with Kawasaki disease decreased and that in the no aneurysm group distensibility ranged between the values in the control group and those in the disappearance group.

Adolescent↗
PubMed1987

Prostaglandin D2 release by guinea pig skin during in vitro anaphylaxis induced by antigen and compound 48/80.

The release of prostaglandin D2 (PGD2), prostaglandin E2 (PGE2), and histamine induced by antigen and compound 48/80 was studied using an in vitro model of anaphylaxis in guinea pig skin. Abdominal skin from ovalbumin-sensitized guinea pigs was cut into 0.5-1.0 mm-thick slices which were incubated in Tyrode solution at 37 degrees C with or without either ovalbumin or 48/80. Released PGD2 and PGE2 were measured by radioimmunoassay and gas chromatography-mass spectrometry, respectively. Release of PGD2 was detectable at 2 min after challenge (50 micrograms/ml ovalbumin), reaching a maximum at about 15 min. Histamine release was more rapid, achieving 50% of maximum at about 4 min compared to about 7 min for PGD2. In 11 experiments incubation with ovalbumin (50 micrograms/ml for 10 min) induced a significant 6-fold increase in PGD2 compared to unchallenged controls (399 +/- 53 and 67 +/- 19 ng/g dry weight skin, respectively; mean +/- SEM) and a net 47.2% histamine release. In contrast, a smaller (27%) rise in PGE2 was found. Indomethacin (14 microns) completely suppressed evoked PGD2 and PGE2 synthesis without evident effect on histamine release, suggesting that the release of histamine in this model is not dependent on prostaglandin production. The mast cell degranulating agent compound 48/80 (50 micrograms/ml) released significant amounts of PGD2 (340 +/- 86 ng/g skin compared to 89 +/- 30 ng/g for control skin, n = 5) but had no appreciable effect on PGE2. These results show that guinea pig skin can synthesize significant quantities of PGD2 in anaphylactic reactions. Prostaglandin D2 produced in acute allergic reactions in skin in vivo may contribute to the inflammatory reaction, either directly or in synergism with other mediators.

Anaphylaxis↗
PubMed1987

Sensitivity to UV radiation of fibroblasts from a Japanese group A xeroderma pigmentosum patient with mild neurological abnormalities.

A 12-year-old girl, suffering from xeroderma pigmentosum (XP), had mild cutaneous and neurological abnormalities. She showed no neurological abnormalities at the age of seven, but areflexia of the patellar tendons at II. She had no malignant tumours. The skin fibroblasts from the patient were about twice as sensitive to the lethal effects of 254 nm ultraviolet (UV) radiation as those of Group C XP patients, and about twice as resistant as those of typical Group A XP patients. The ability of these fibroblasts to reactivate UV-damage adenovirus 5 was intermediate between those of Group C and typical Group A patients. The patient's cells were assigned to genetic complementation Group A by use of the cell-fusion technique. This is the first case in Japan of a Group A XP patient with mild neurological abnormalities. The mild cutaneous manifestations of this patient may be explained by the residual ability of the cells to repair UV-damaged DNA.

Adenoviruses, Human↗
PubMed1987

Staging of bladder carcinoma by magnetic resonance imaging. A preliminary report.

Magnetic resonance imaging (MRI) of bladder carcinoma was performed in 10 patients who subsequently underwent operations for tumor staging. MRI was performed with a 0.1 T resistive magnetic resonance unit. Images were obtained in the transverse, coronal and sagittal directions with different repetition and echo times. Simultaneously, computed tomography (CT) was performed in 9 of the 10 patients. The accuracy of MRI and CT staging was then evaluated by comparison with the staging from pathologic diagnosis. All of the tumors, which were 2.3-6.3 cm in diameter, were readily depicted by both imaging techniques. The overall accuracy of MRI staging for the 10 patients in whom staging had been pathologically confirmed was 90%, while the accuracy of CT staging for the 9 patients was 55%. Although no statistically significant differences in accuracy between CT and MRI staging can be established on the basis of the above results because of the small number of patients included in this study, MRI appears to be a very useful modality for staging bladder carcinoma.

Adult↗
PubMed1987

Binding of 131I-labeled tissue-type plasminogen activator on de-endothelialized lesions in rabbits.

Tissue-type plasminogen activator (t-PA) which has a high affinity for fibrin in the clot, was labeled with 131I by the iodogen method, and its binding to de-endothelialized lesions in the rabbit was measured to assess the detectability of thrombi. The de-endothelialized lesion was induced in the abdominal aorta with a Fogarty 4F balloon catheter. Two hours after the de-endothelialization, 131I-labeled t-PA (125 +/- 46 microCi) was injected intravenously. The initial half-life of the agent in blood (n = 12) was 2.9 +/- 0.4 min. The degree of binding of 131I-labeled t-PA to the de-endothelialized lesion was evaluated at 15 min (n = 6) or at 30 min (n = 6) after injection of the agent. In spite of the retention of the biochemical properties of 131I-labeled t-PA and the presence of fibrin deposition at the de-endothelialized lesion, the binding of t-PA to the lesion was not sufficiently strong. Lesion-to-control ratios (cpm/g/cpm/g) were 1.65 +/- 0.40 (at 15 min) and 1.39 +/- 1.31 (at 30 min), and lesion-to-blood ratios were 1.39 +/- 0.32 (at 15 min) and 1.36 +/- 0.23 (at 30 min). These results suggest that radiolabeled t-PA may be inappropriate as a radiopharmaceutical for the scintigraphic detection of a pre-existing thrombotic lesion.

Animals↗
PubMed1987

[Myocardial perfusion detected using digital subtraction angiography as compared with X-ray CT and Tl-201 myocardial imaging].

Forty-two patients who underwent aorto-coronary bypass surgery were examined with intra-aortic digital subtraction angiography (IADSA) to detect abnormalities of myocardial blood perfusion. Tl-201 myocardial imaging and cardiac X-ray CT were performed nearly simultaneously about one month postoperatively. Cardiac imaging using IADSA was performed at a rate of 30 frames/sec with matrix size of 512 x 256. Time density curves of each pixel in the region of the myocardium of the left ventricle were post-processed to obtain functional images. The maximal concentration (Cmax), integration of the time-density curve (Cinteg), mean transit time (MTT), Cmax/MTT and Cinteg/MTT were computed for each pixel. Cmax and Cinteg are parameters related to the volume of the coronary vascular bed. Cmax/MTT and Cinteg/MTT are parameters related to the regional myocardial blood flow. These functional images showed hypoperfusion areas in 35 of 37 ischemic segments confirmed by wall motion in digital subtraction left ventriculography, Tl-201 myocardial imaging and ECG. Normal perfusion areas of the functional images were observed in 18 of 54 infarcted segments. These results show the complexities of myocardial perfusion in old myocardial infarction.

Coronary Angiography↗
PubMed1987

[New imaging technique for the cardiovascular system: introduction to DSA].

This introduction to digital subtraction angiography (DSA) was presented before the presentations of the panelists. DSA is a new imaging procedure for evaluating cardiovascular disease, images with successful digitization of X-ray picture achieved following the development of CT. DSA is less invasive than ordinary angiocardiography; it features real time imaging, good spatial and temporal resolution, and the capability of providing functional and anatomical information. Although DSA has been applied mainly to the vascular system, its use is being extended to the evaluation of ischemic heart disease. One disadvantage of DSA consists of misregistration artifacts which are caused by temporal subtraction technique. In attempts to overcome this disadvantage, energy subtraction, hybrid subtraction, and the application of a matched filter technique have been investigated. The recent development of angiographic contrast media with low osmolarity will serve to extend the indications for DSA.

Angiography↗