[Capture of native and in vivo modified 125I-low density lipoproteins by fibroblasts and macrophages. Effect of high density lipoproteins on this process].

Unspecific interaction was analyzed between native 125I-lipoproteins of low density (LDL) as well as 125I-LDL, maintained in rabbit circulation during 4 hrs, and fibroblasts and macrophages. Alterations in properties of the LDL, occurred in blood, were accompanied by an increase in their affinity towards macrophages and a decrease in the affinity to fibroblasts. In vivo effect of HDL on catabolism of LDL was manifested as inhibition of extracellular modification of LDL and elimination of them from circulation, and in vitro--as inhibition of the native LDL capture by fibroblasts and, especially, by macrophages.

[Accumulation of pyrophosphate in the myocardium in post-infarction cardiosclerosis].

A study of the relationship between the frequency of labelled pyrophosphate detection in the heart muscle and the incidence of clinical signs of heart failure or angina in 185 postmyocardial-infarction patients demonstrated that the distribution of patients with postinfarction cardiosclerosis among the positive and negative 99mTc-pyrophosphate scintigraphy groups was governed by the presence of heart failure in these patients, a finding suggestive of the scarry fields within the myocardium as the principal cause of myocardial accumulation of labelled pyrophosphate in postinfarction cardiosclerosis. Pyrophosphate accumulation in patients with postinfarction cardiosclerosis can be regarded as an indicator of unfavorable developments, as confirmed by one-year follow-up results in 114 patients.

Studies on the succinate dehydrogenating system. Isolation and properties of the mitochondrial succinate-ubiquinone reductase.

A simple procedure for preparation of highly purified soluble succinate-ubiquinone reductase from bovine heart mitochondrial particles is described. The enzyme exhibits four major bands on sodium dodecyl sulfate gel electrophoresis and contains (nmol per mg protein): covalently bound flavin, 6; non-heme iron, 53; acid-labile sulfur, 50; cytochrome b-560 heme, 1.2.

Interaction between the mitochondrial ATP synthetase and ATPase inhibitor protein. Active/inactive slow pH-dependent transitions of the inhibitor protein.

The rate of mitochondrial ATPase inactivation by the naturally occurring inhibitor protein in the presence of saturating ATP and Mg2+ at pH 8.0 depends hyperbolically on the amount of inhibitor added; the upper limit of an apparent first-order constant for the inactivation process is 1.0(-1) at 25 degrees C.

[Clinical importance of 99mTc-pyrophosphate scintigraphy in the bicycle ergometry test].

The clinical value of myocardial scintigraphy with 99mTc-pyrophosphate in conjunction with bicycle ergometry was assessed through the correlation of the latter's results with the clinical course of coronary heart disease over 1 year in 21 patients with first myocardial infarction during its early healing stage and 17 anginal patients without a history of myocardial infarction. The disease ran a stable course at the time of the testing in all the patients; later on, 11 of those developed various complications associated with coronary heart disease, or died. Three scintigraphic recordings were made: prior to, at the peak of, and after the exercise.

[Determination of the necrotic mass in inferior myocardial infarct by standard electrocardiography].

A study of 28 patients with acute inferior myocardial infarction, who died 3 days after the attack, involved the comparison of necrosis weight data, as determined anatomically, with those obtained through the measurement of the R wave height and the Q wave (QS complex) depth, taken from standard leads and amplified remote leads from limbs. The comparison results suggest that intravital electrocardiographic determination of the necrosis weight is possible. A formula has been derived for the determination of the necrotized tissue weight (in grams) in patients with left-ventricular inferior infarction.

Pyridoxal phosphate-induced dissociation of the succinate: ubiquinone reductase.

Treatment of the soluble ubiquinone-deficient succinate: ubiquinone reductase with pyridoxal phosphate results in the inhibition of the carboxin-sensitive ubiquinone-reductase activity of the enzyme. The inactivation is prevented by the soluble homolog of ubiquinone (Q2) but is insensitive to the dicarboxylates interacting with the substrate binding site of succinate dehydrogenase. The reactivity of the pyridoxal phosphate-inhibited enzyme with different electron acceptors suggests that the observed inhibition is due to the dissociation of succinate dehydrogenase from the enzyme complex.

[Interaction of mitochondrial succinate:ubiquinone reductase with thenoyltrifluoroacetone and carboxin].

Thenoyltrifluoroacetone (TTA) and carboxin inhibit soluble ubiquinone-deficient succinate: ubiquinone reductase according to the mixed type (with respect to added Q2) inhibition. pattern. The Ki values for the inhibitors are mutually dependent, thus indicating the presence of a single binding site for both TTA and carboxin.

[Serous papillary cystadenoma of the rectum].

The authors describe a rare clinical observation: development of the serous papillary cystadenoma of the borderline malignancy in the rectum in a 53 year-old women. 20 years ago she was operated on and bilateral ovarian tumors were removed. The authors regard the tumor of the rectum to have arisen de novo.

[Clinical evaluation of continuous myocardial electrostimulation of the atria in the sick sinus syndrome].

Forty-four patients with the syndrome of pacemaker weakness were subjected to the operation of the continuous electrostimulation of the right atrium from the infrasternal access using sutureless electrodes. Patients with grave attendant diseases were shown to benefit from this procedure. The use of Soviet commercially available sutureless electrodes makes it possible to considerably simplify the main stage of the operation and to ensure the reliable functioning of the biocontrolled cardiostimulators at the long-term postoperative period.

[Indicators of scintigraphy using technetium Tc 99m pyrophosphate in angina pectoris in relation to the activity of the pituitary-adrenal system].

The effect of exercise on the parameters of the scintigraphy of the myocardium with labelled pyrophosphate was studied in 35 patients with coronary heart disease and angina of effort and at rest with regard to the activity of the pituitary-adrenal cortex system. The functional status of this system was evaluated on the basis of data on the blood changes in somatotrophic hormone and cortisol. The use of a scoring system made it possible to identify four types of the pattern of the scintigraphic parameters.

[Clinical significance of the size of the necrotic area and the rate of its formation in the acute period of myocardial infarct].

The authors suggest a new method of interpreting the kinetics of the isoenzyme MB CPK in the body based on mathematical modelling. This method have made it possible to increase the accuracy of determining the necrotic size and to calculate the temporal parameters (rate and acceleration) of the formation of the necrotic focus. The studies have shown that these temporal parameters allow the timely (within the first 10-12 h of the disease) objective and quantitative assessment of the disease severity.

[Phenomenon of pyrophosphate accumulation in the prognosis of different forms of ischemic heart disease].

The results of pyrophosphate 99mTc scintigraphy of the myocardium during exercise were compared with the parameters of the tolerance and adaptation to the load and the frequency of manifestations of myocardial ischemia during bicycle ergometry in relation to the prognostic value with regard to coronary heart disease (CHD) development. The studies involved 21 patients with myocardial infarction at the early recovery period and 23 CHD patients without a history of myocardial infarction. Manifestations of myocardial ischemia and the pattern of pyrophosphate build-up in the myocardium during exercise are approximately equally informative with regard to the prognosis of a high risk of complications in CHD patients.

[Means of differential diagnosis between angina pectoris and neurocirculatory dystonia].

Plasma somatotropic hormone and cortisol were measured at rest, at the peak of physical stress and 2 hours after the discontinuation of exercise in 15 normal male subjects, 18 male patients with neurocirculatory dystonia and 69 with angina pectoris. The determination of one-dimensional hyperplanes of plasma STH and cortisol during and after exercise allows one to distinguish anginal patients from those with neurocirculatory dystonia and make a diagnosis in patients with nonspecified chest pains.

[Interaction of succinate dehydrogenase and oxaloacetate].

The equilibrium and rate constants for interaction of the reduced and oxidized membrane-bound succinate dehydrogenase (EC 1.3.99.

Evidence for an essential arginine residue in the substrate binding site of the mammalian succinate dehydrogenase.

Phenylglyoxal and 2,3-butanedione rapidly inactivate membrane-bound or soluble bovine heart succinate dehydrogenase. The inhibition of the enzyme by these reagents is completely prevented by saturating concentration of malonate. The modification of the active site sulfhydryl group by p-chloromercuribenzoate decreases the rate of the enzyme inhibition by phenylglyoxal and abolishes the protective effect of malonate.

[Dissociation constants of succinate dehydrogenase complexes with succinate, fumarate and malonate].

The rates of the oxidized (Eox) and reduced (Ered) (by NAD . H through the ubiquinone pool) succinate dehydrogenase inhibition by N-ethyl-maleimide are equal and obey pseudo-first order kinetics. The protection of the enzyme against irreversible alkylation was used to quantitate the dissociation constants for Eox and Ered complexes with fumarate, succinate and malonate under conditions when no intramolecular redox reactions might occur.

[Interaction of the sulfate ion with the active site of succinate dehydrogenase].

A new type of slow changes of the succinate dehydrogenase (EC 1.3.99.

Interaction of the membrane-bound succinate dehydrogenase with substrate and competitive inhibitors.

The protective effect of dicarboxylates on the active-site-directed inhibition of the membrane-bound succinate dehydrogenase by N-ethylmaleimide, steady-state kinetics methods for Ki and Ks determinations, and equilibrium studies were employed to quantitate the relative affinities of succinate, fumarate, malonate and oxaloacetate to the reduced and oxidized species of the enzyme. A more than 10-fold difference in the relative affinities of the reduced and oxidized succinate dehydrogenase to succinate, fumarate and oxaloacetate is found, whereas the reactivity of the active-site sulphydryl group does not depend on the redox state of the enzyme. The redox-state-dependent changes in the affinity of the membrane-bound succinate dehydrogenase to oxaloacetate can be quantitatively accounted for by a 10-fold increase in the rate of dissociation of the enzyme-inhibitor complex which occurs upon reduction of the enzyme.