Search PubMed⌕ Search

Biomedical subjects

T Sonnenfeld

Publications and source records attributed to T Sonnenfeld.

6 recordsLinked to original sources
PubMed1992

Mechanisms for differences in lipolysis between human subcutaneous and omental fat cells.

Catecholamine-regulation of lipolysis and beta-adrenoceptor binding isoterms were studied in human sc and omental isolated fat cells from 24 subjects undergoing elective cholecystectomy. The lipolytic sensitivity of the nonselective beta-agonists epinephrine and isoprenaline as well as the selective agonists norepinephrine (beta 1) and terbutaline (beta 2) was significantly increased 5-10 times in omental fat cells. On the other hand, no regional difference in antilipolytic sensitivity was seen for the alpha 2 agonist clonidine. No regional difference in lipolytic action was seen when measuring the effect of forskolin, (Bu)2cAMP or enprofylline, which act at different postadrenoceptor steps in the lipolytic cascade. Lipolysis data showed no sex differences. A beta 1-pattern was seen in both regions when lipolysis dose-response curves were arranged in order of potency. Radioligand saturation experiments with the nonselective beta-antagonist 125I-cyanopindolol and competition experiments between this radioligand and the selective antagonists CGP-20,712-A (beta 1) and ICI-118551 (beta 2) showed a 2-fold increase in the amount of beta 1- and beta 2-adrenergic receptors in omental as compared to sc fat cells (P less than 0.02). Competition studies with the same radioligand and the nonselective beta-agonist isoprenaline showed no regional differences in terms of receptor affinity (Kd high 10 nM and Kd low 1 microM) or in relative fraction of receptors in the high affinity state (35%). It is concluded that an increased lipolytic sensitivity for beta 1- and beta 2-agonists can be due to an increase in the amount of the two adrenoceptor subtypes in omental fat cells and thereby explain why catecholamines are more lipolytic in omental cells than in sc fat cells.

Abdomen↗
PubMed1979

Conversion of arachidonic acid to prostaglandins in homogenates of human skeletal muscle and kidney.

The capacity of human skeletal muscle and kidney homogenates to synthetize prostaglandins (PGs) from exogenous precursor was investigated. Low-speed supernatants of muscle as well as renal medullary and cortical homogenates were incubated with 14C-labelled arachidonic acid (14C-AA) prepared as a sodium salt. 14C-PGs in the incubates were extracted, separated with thin-layer chromatography (TLC) and quantified by radioscanning. In the skeletal muscle incubates 14C-AA was converted into 14C-PGs with a time-dependent yield, most effectively after 10--15 min incubation. Well-defined radiopeaks parallel to unlabelled standards of PGD2, PGE2, PGF2 alpha and 6-keto-PGF1 alpha were obtained in the chromatograms. PGE2 was the main PG formed, constituting over 50% of 14C-activity, whereas 6-keto-PGF1 alpha, PGD2 and PGF2 alpha were found in considerably lower proportions. In the renal medullary incubates, PGE2 likewise accounted for the largest part of 14C-PGs formed, but significant relative amounts of PGF2 alpha and PGD2 were also found. A minor peak, corresponding to 6-keto-PGF1 alpha and thus indicating formation of PGI2, was also obtained. In contrast to the medulla, no 14C-PGs could be found in the renal cortical incubates. The results demonstrate the existence of a considerable tissue specificity in the quantitative and qualitative expression of PG biosynthesis in man.

Adult↗
PubMed1979

LEg venous oxygen saturation in the evaluation of intra-operative blood flow during arterial reconstructive surgery.

In twenty-four patients, undergoing a femoro-popliteal saphenous vein bypass graft for symptomatic atherosclerotic occlusion of the superficial femoral artery, oxygen saturation values for the femoral and popliteal veins were compared to the directly measured blood flows in the common femoral artery and in the bypass graft, respectively. Blood flow and venous oxygen saturation increased significantly after transfusion of 900 ml of blood. Pharmacological vasodilation caused a significant increase in blood flow both before and after transfusion, whereas the changes in venous oxygen saturation were significant only before blood transfusion. A close statistical relationship was found between initial femoral venous oxygen saturation and initial blood flow in the common femoral artery as well as between initial popliteal venous oxygen saturation and initial byapss blood flow. However, especially at low saturation values, the evaluation of blood flow was very uncertain. Whole leg and lower leg oxygen uptakes were not altered by intraoperative changes in blood volume. It is concluded that blood flow in the common femoral artery and the bypass graft can be roughly estimated from analysis of oxygen saturation in the femoral and popliteal veins, respectively. Furthermore, by determining leg venous oxygen saturation both before and after flow augmentation, induced by pharmacological vasodilation, a conception of the load on the vascular system may be obtained.

Aged↗
PubMed1979

Prognostic significance of intra-operative blood transfusions and flow measurements in reconstructive vascular surgery.

Intra-operative measurement of leg blood flow is useful not only for the detection of a technical fault. It has also proved to be a sensitive method to disclose hypovolaemia. Thus, if the blood volume is not restored, the peripheral vasoconstrictor tone remains elevated. In such a state, the basal leg blood flow is low, but increases markedly on pharmacological vasodilation. In a normovolaemic situation, however, the basal blood flow is higher with a less pronounced increase following vasodilation. In the present study, intra-operative measurements of graft blood flow using an electromagnetic flowmeter have been employed to evaluate the blood substitution needed during 114 consecutive reconstructions with femoro-popliteal reversed saphenous vein bypass grafts. The measurements resulted in a blood transfusion therapy that was, on an average, 38% higher that it would have been, if substitution had been based simply on a calculation of blood losses from volume measurements in the suction apparatus and from the drapes and swabs. Only three graft thromboses developed within the first month. The flow rate of these grafts was much lower than the grafts remaining open. The low early thrombosis frequency (2.8%) compares favourably with previous reports, which might partly be explained by generous intra-operative blood transfusion.

Adult↗