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Biomedical subjects

Y Ueda

Publications and source records attributed to Y Ueda.

At least 1,045 records · Page 58Linked to original sources
PubMed1983

[Tomographic analysis of CBF in cerebral infarction].

Cerebral perfusion was examined in various types of occlusive disease by computed tomographic CBF method. The method utilized has several advantages over conventional studies using isotope, providing high resolution images in a direct relation to CT anatomy. Ten representative cases were presented from 25 consecutive cases of occlusive disease studied by this method. The method included inhalation of 40 to 60% xenon with serial CT scanning for 25 min. K (build-up rate), lambda (partition coefficient) and CBF values were calculated from HU for each pixel and Xe in expired air, based on Fick's principle, and displayed on CRT as K-, lambda- and CBF-map separately. CBF for gray matter of normal control was 82 +/- 11 ml/100 gm/min and that for white matter was 24 +/- 5 ml/100 gm/min. The ischemic threshold for gray matter appeared to be approximately 20 ml/100 gm/min, as blood flow in focus of complete infarction was below this level. Blood flow between 20-30 ml/100 gm/min caused some change on CT, such as localized atrophy, cortical thinning, loss of distinction between gray and white matter and decreased or increased density, which were considered to be compatible with pathological changes of laminar necrosis or gliosis with neuronal loss. In a case with occlusion of middle cerebral artery with subsequent recanalization, causing hemorrhagic infarct, hyperemia was observed in the infarcted cortex that was enhanced by iodine. Periventricular lucency observed in two cases, where blood flow was decreased below threshold, could be classified as "watershed infarction" mainly involving white matter. In moyamoya disease, blood flow in the anterior circulation was decreased near ischemic level, whereas that in basal ganglia and territory of posterior cerebral artery was fairly preserved, which was compatible with general angiographic finding of this disease.

Adult↗
PubMed1983

[Changes in CBF pattern after bypass surgery studied by CT with Xe enhancement].

UNLABELLED: Using a new method for rCBF measurement by serial CT scanning with non-radioactive xenon enhancement, CBF was measured before and/or after microsurgical anastomosis in five cases of focal cerebral ischemia. MATERIALS AND METHODS: Studies were carried out on 2 cases of MCA occlusion, 2 of IC occlusion, and 1 of "Moyamoya" disease. CBF was measured both before and after surgery in 4 cases, and the remaining case was measured after anastomosis. Pre-operative CBF was measured 1.4 +/- 0.5 months after the onset and post-operative CBF was 2 +/- 1 months after surgery. While 50 to 70% non-radioactive xenon was inhaled for 25 min and then discontinued, serial CT scanning was carried out every 3 min. K-map (clearance rate), lambda-map (partition coefficient), and CBF-map were displayed on CRT as images of each value. RESULTS: In all cases, initial pre-operative CBF decreased not only in the ipsilateral hemisphere, but also in the contralateral hemisphere. Especially in the major stroke cases, CBF reduction in the low density areas seen in CT was more than 75% of normal values. After microsurgical anastomosis, CBF increased in both hemispheres. In two cases of reversible ischemic attacks without any change in CT, the CBF markedly increased in central areas of ischemia and the CBF values became higher than normal value, that is hyperemia. On the contrary, in the central areas of the major stroke cases, that is, the low density areas in CT, CBF was still very low (under 25% of normal value) after anastomosis. However, in these cases, marked hyperemia was seen in the surrounding area of ischemic focus.

Adolescent↗
PubMed1982

Selective bronchial suctioning in the adult using a curve-tipped catheter with a guide mark.

Our results of previous and successive studies indicate that torque control of curve-tipped catheters is easily accomplished by placing a guide mark on the catheter. Thus, a guide mark was made on a curve-tipped 14 FG Portex suction catheter using a felt pen. The efficacy of selective bronchial suctioning using this catheter was studied in 50 patients. Directed suctioning of the left and right bronchial passages was performed in each patient 3 times and once, respectively, with the head in the midline position. The success rate of left bronchial suctioning was 92% (138/150 attempts) and success in right bronchial suctioning 98% (49/50 attempts). The curve-tipped catheter with a guide mark significantly improved the success rate of left bronchial entry over the previous rate from 50% to 92%.

Bronchi↗
PubMed1982

Effects of angiotensin I converting enzyme inhibitor (SQ 14,225) on the responses of blood pressure and steroid hormone to angiotensin II and ACTH infusion in hypertensive subjects.

The effects of the converting enzyme inhibitor, SQ 14,225, on the renin-angiotensin system, adrenal function and blood pressure were investigated in 14 hypertensive patients, i.e., 10 with essential hypertension (EH) and 4 with renovascular hypertension (RVH). The mean blood pressure (MBP) and plasma aldosterone showed significant decreases in the EH with normal renin (NR) group and in the RVH group but no significant changes in the EH with low renin (LR) group. Plasma renin activity (PRA) increased significantly in the EH and NR group and in the RVH group but showed no significant change in the EH with LR group. Significant correlations were found between the fall in MBP after SQ 14,225 treatment and the pretreatment levels of PRA or plasma aldosterone. In an ACTH infusion study, the response of plasma aldosterone to ACTH revealed significant decreases after SQ 14,225 administration. In an angiotensin II (A II) infusion study, the response of plasma aldosterone was unchanged after SQ 14,225 administration. However, the pressor responses to A II infusion with SQ 14,225 were significantly higher than those without SQ 14,225. From these findings, it is concluded that the antihypertensive mechanism of SQ 14,225 may be due mainly to the decrease in levels of endogenous A II and that the reduction in plasma aldosterone after SQ 14,225 were significantly higher than those without SQ 14,225. From these findings, it is concluded that the antihypertensive mechanism of SQ 14,225 administration may be due to reduction of endogenous A II levels by converting enzyme inhibition.

Adolescent↗
PubMed1982

Response of plasma ACTH and adrenocortical hormones to potassium loading in essential hypertension.

The effect of potassium loading on plasma adrenocortical hormones concentrations in 9 patients with essential hypertension (EH) was investigated. The plasma renin activity (PRA), plasma concentrations of growth hormone (GH), ACTH, cortisol, deoxycorticosterone (DOC), 18-hydroxy-deoxycorticosterone (18-OH-DOC) and aldosterone, and serum electrolytes were measured before and after potassium chloride (KC1) infusion (0.33 mEq/kg/h, for one hour). The KC1 infusion caused significant increases in serum potassium levels and plasma levels of GH, ACTH, cortisol, DOC, 18-OH-DOC and aldosterone, while PRA remained unchanged. Regression analysis at 30 min revealed significant positive correlations between delta ACTH and delta cortisol, between delta ACTH and delta DOC, between delta ACTH and delta 18-OH-DOC. However, the relationship between delta ACTH and delta aldosterone was not statistically significant. These results suggest that (1) acute potassium loading causes a significant increase in the plasma ACTH level and increased levels of adrenocortical hormones may be produced by increased ACTH secretion, and (2) it may be considered that a part of the increased level of plasma aldosterone following acute potassium loading may arise from increased ACTH secretion in EH.

Adrenal Cortex Hormones↗