Factor VII Activation, Apolipoprotein A-I and Reverse Cholesterol Transport: Possible Relevance for Postprandial Lipaemia

Postprandial lipaemia is associated with activation of factor VII (FVII) and efflux of cholesterol from tissues to nascent plasma high density lipoproteins (HDL) containing apolipoprotein A-I (apo A-I). To determine whether FVII activation and cholesterol efflux occur together in other situations, the responses to intravenous infusion of HDL-like apo A-I/phosphatidylcholine discs were measured in 10 healthy men. Disc infusion (40 mg apo A-I/kg body weight) over 4 h was followed by increases in HDL cholesteryl ester and plasma apo A-I (p <0.0001). Significant activation of FVII was apparent during infusion in fasting subjects (p = 0.03), activated FVII averaging 123% of baseline value by 12 h (p <0.0001). Plasma thrombin-antithrombin (TAT) complex increased to 156% of baseline level by 12 h (p >0.05) but individual responses differed considerably. Peak TAT post-infusion was associated inversely with peak HDL triglyceride concentration (p = 0.004). The coagulation responses to disc-infusion may be due to transfer of phosphatidylserine to cell surfaces during cholesterol efflux.

Factor VII activation, apolipoprotein A-I and reverse cholesterol transport: possible relevance for postprandial lipaemia

Postprandial lipaemia is associated with activation of factor VII (FVII) and efflux of cholesterol from tissues to nascent plasma high density lipoproteins (HDL) containing apolipoprotein A-I (apo A-I). To determine whether FVII activation and cholesterol efflux occur together in other situations, the responses to intravenous infusion of HDL-like apo A-I/phosphatidylcholine discs were measured in 10 healthy men. Disc infusion (40 mg apo A-I/kg body weight) over 4 h was followed by increases in HDL cholesteryl ester and plasma apo A-I (p <0.0001). Significant activation of FVII was apparent during infusion in fasting subjects (p = 0.03), activated FVII averaging 123% of baseline value by 12 h (p <0.0001). Plasma thrombin-antithrombin (TAT) complex increased to 156% of baseline level by 12 h (p >0.05) but individual responses differed considerably. Peak TAT post-infusion was associated inversely with peak HDL triglyceride concentration (p = 0.004). The coagulation responses to disc-infusion may be due to transfer of phosphatidylserine to cell surfaces during cholesterol efflux.

Effects of reserpine on expression of the LDL receptor in liver and on plasma and tissue lipids, low density lipoprotein and fibrinogen in rabbits in vivo

The effects of administering reserpine (0.1 mg/kg) or 17alpha-ethinyloestradiol (2.5 mg/kg) to New Zealand White rabbits on low density lipoprotein receptors in liver, on plasma low density lipoprotein and fibrinogen and on plasma and tissue lipids were determined. Blood pressure and heart rate were also followed. The drugs were injected subcutaneously into conscious unrestrained rabbits for 5 days. On the 6th day homologous 125I-tyramine cellobiose labelled low density lipoprotein (125I-TC-LDL) was injected intravenously and 24 h later the animals were killed. Compared to controls, reserpine significantly increased LDL receptor expression in the liver by about threefold, and reduced total cholesterol in plasma, aorta and heart, without affecting plasma triglycerides. The reductions in plasma cholesterol and heart were due to decreases in both unesterified and esterified cholesterol. Similar effects were observed with oestrogen, except that there was no change in esterified cholesterol in aorta. In liver, a decrease of 24% in total cholesterol was due mainly to decreased esterified cholesterol. In adrenal glands total cholesterol increased by 25%. Reserpine significantly accelerated the plasma clearance of intravenously injected homologous 125I-TC-LDL and reduced its accumulation in aortic wall. Neither reserpine nor oestradiol affected blood pressure, haematocrit or plasma fibrinogen. The results suggest that reserpine is an affective anti-atherogenic drug capable of decreasing cholesterol in plasma, arteries and heart by increasing high affinity LDL receptors in the liver.

[The morphogenesis of the retinal neural layer and of the optic nerve in the normal white rat and under the action of large doses of x-ray irradiation during prenatal ontogeny]

Development of retina nerve layer and optic nerve were studied in 50 embryos and fetuses of albino rat in normal embryogenesis and in 55 embryos affected by large doses of X-ray irradiation (2.24 Cy) on d 10-14 of pregnancy (second critical period-a period of placentation and organogenesis). Main regularities in the development of the structures studied were demonstrated in intact fetuses. In the experiment the progeny subjected to X-ray irradiation showed basically bilateral abnormalities in development of retina nerve layer, optic nerve and its coats.

Collagen-targeted antibodies inhibit platelet-dependent thrombosis in vivo

Subendothelial collagen is one of the main triggers of platelet-dependent thrombus formation in arteries. The antithrombotic effects of rabbit polyclonal inhibitory antibodies to rat collagen type I-III and of murine non-inhibitory monoclonals to human recombinant single-/two-chain urokinase-type plasminogen activator (rscu-/rtcu-PA), cross-reacting with rat scu-/tcu-PA and their chemically synthesized conjugate, were studied both in vitro and in vivo. Anticollagen antibodies and bispecific conjugate inhibited human platelet adhesion, aggregation and formation of thrombus-like structures induced by rat collagen immobilized on the polystyrene surface in a condition mimicing a high shear rates in the large elastic arteries. Monoclonals to human rscu-/rtcu-PA did not block the collagen-induced platelet activation in vitro. The short-term treatment of the collagen-soaked silk thread by the collagen antibodies suppressed the platelet-dependent thrombus formation in the arterio-venous shunt in rats by 56 +/- 4% (P < 0.05). Bispecific conjugate, directed to collagen and endogenous rat scu/tcu-PA inhibited thrombus formation by the same factor as anticollagen antibodies. The treatment of collagen-adsorbed conjugate by human rtcu-PA did not increase the antithrombotic effect. The present results suggest, that the local administration of the anticollagen antibodies to the site of vascular injury can be an efficient tool for prophylaxis of platelet-dependent thrombus formation in arteries at thrombolysis or percutaneous transluminal coronary angioplasty.

[The development and structure of the optic nerve in normal embryos and fetuses of the white rat and after x-ray irradiation]

With the aim to reveal the ionising radiation effect to formation and structure of the optic nerve (ON), 55 white rat intact embryos and fetuses and 77 experimental embryos and fetuses, subjected to x-ray irradiation on the 10th-14th day of development, have been studied. The main regularities in formation of the ON have been stated under normal conditions. Certain disturbances in formation of the ON and in the internal membrane of the optic vesicle (future retina) under effect of x-rays in the dose of 2.24 Gy have been detected during the intrauterine period of development--folds, rosellas of retina, retardation in differentiation of the retina nervous layer, aberration of the ON growth with a subsequent reduction, the ON hypo- and aplasia, retardation in formation of neural sheaths, absence of intraspace between the sheaths.

[Comparative evaluation of methods of myocardial scintigraphy using 99mTc-Sn-glucohepatonate and 99mTc-Sn-pyrophosphate in the diagnosis of acute myocardial infarction and unstable stenocardia]

Scintigraphy with 99mTc -Sn-glucoheptonate permits the determination of the focus of transmural myocardial infarction at the earliest stages of the disease (from three hours to the fifth day of the disease) whereas scintigraphy with 99mTc -Sn-pyrophosphate makes it possible to follow-up the zone of transmural infarction from Day 2 through Day 7-10. Both methods fail to provide enough information to diagnose non-transmural myocardial infarction. A comparative evaluation of the nature of glucohepatonate and pyrophosphate incorporation in the myocardium of patients with unstable angina is suggestive of the severity of ischemic changes in the myocardium.

[Certain humoral factors in acute myocardial infarct complicated by cardiogenic shock]

The activity of the sympathoadrenal and renin-angiotensin-aldosterone systems was studied in patients with myocardial infarction complicated by cardiogenic shock. During the initial 12 hours after the onset of myocardial infarction an increased plasma level of adrenalin and noradrenal is observed, which then returns to the normal level on the 3rd day. In cases of cardiogenic shock a lower content of catecholamines in blood is noted. The determinations of renin activity in the plasma of peripheral venous blood demonstrated that it was increased since the 1st day of the disease in the myocardial infarction patients, but that its maximum elevation fell within the 7th--10th days. In patients with cardiogenic shock the plasma renin activity was much higher than in those with uncomplicated myocardial infarction. Urine aldosterone excretion was higher in patients with cardiogenick shock since the 1st day of the disease than in those with an uncomplicated course of myocardial infarction. The study of the electrolyte balance in patients with myocardial infarction complicated by cardiogenic shock demonstrated that on the 1st day of the disease the potassium level in plasma and erythrocytes was decreased, while the sodium concentration was somewhat increased.