[Status of lipid metabolism in rabbits, delivered from females with moderate alimentary hypercholesterolemia]. / Sostoianie lipidnogo obmena u krolikov, rodivshikhsia ot samok s umerennoi alimentarnoi giperkholesteinemiei.

Offspring of rabbits fed with cholesterol diet during pregnancy and/or lactation was more sensitive to fat load versus the offspring of rabbits fed with standard diet. Such enhancement of hyperlipidemic reaction is predominantly due to the enhanced rate of blood cholesterol increase (i.e., secretion of cholesterol-containing lipoproteins) but not to the decreased rate of cholesterol elimination from the blood stream. This was confirmed by monitoring the fate of human low-density lipoproteins intravenously injected in rabbits. The data indicate certain alterations of cholesterol metabolism regulation in the offspring of rabbits with alimentary hypercholesterolemia. Hypercholesterolemia of pregnant and lactating rabbits is important for the formation of the lipid metabolism in their offspring because cholesterol levels in the serum of female rabbits positively correlate with the expression of hypercholesterolemic and hypertriglyceridemia reactions of their offspring in response to fat load and with kinetic parameters which characterize the increase in cholesterol and its elimination from the blood stream during fat load.

[Isolation and properties of triglyceride lipase from the rabbit liver]. / Vydelenie i svoistva triglitseridlipazy pecheni krolika.

Using affinity chromatography on heparin-Sepharose 4B, triglyceride lipase was isolated from rabbit liver tissue and purified. The specific activity of the enzyme isolated from the usual homogenate was equal to (3.8 +/- 1.2) x 10(3) mumol/hour/mg protein. After treatment of liver tissue homogenates with liquid nitrogen the enzyme activity increased severalfold as compared to the enzyme isolated from the usual homogenate. The dependences of the triglyceride lipase activity on the concentrations of the protein (enzyme), substrate (triglyceride), albumin (fatty acid acceptor) and pH were studied. The isolated form of liver triglyceride lipase was found to have two pH optima at 6.5 and 8.5.

[Triglyceride lipase from the rabbit liver]. / Triglitseridlipaza pecheni krolika.

Unlike the rabbit blood plasma the high-activity triglyceride lipase which does not require a protein cofactor and is resistant to 1 M of NaCl has been revealed in the liver of this animal. Rapid freezing of the liver tissue by liquid nitrogen before homogenization induced a sharp increase in the enzyme activity level and extraction of the active enzyme without heparin usually added to the homogenate. The specific activity of hepatic lipase purified from the ordinary heparin-containing homogenate by affinity chromatography on heparin-sepharose 4B was equal to 3800 microM of FFA/h per mg of protein. If the homogenate previously treated with liquid nitrogen was used as a source of enzyme, the specific activity of hepatic lipase was higher, namely, 13,000 and 19,000 microM of FFA/h per mg of protein in the presence or absence of heparin, respectively.

[Inhibition of lipoprotein lipolysis by polyarginine and evaluation of the mechanism of its interaction with lipoprotein lipase]. / Ugnetenie poliargininom lipoproteidlipoliza i vyiasnenie mekhanizma ego vzaimodeistviia s lipoproteidlipazoi.

It was found that polyarginine (Mr 40 000-60 000) is a strong inhibitor of the lipoprotein lipase activity in vivo and in vitro. The inhibitory effect in vivo was observed after a single intravenous injection of 0.85-3.5 mg/kg to rabbits, that in vitro at the polypeptide concentration of greater than or equal to 2.5 micrograms/ml. Within the first few hours after intravenous injection of polyarginine hyperlipidemia occurred with an obvious increase in the plasma triglyceride and VLDL fractions and a slight decrease of the LDL and HDL fractions. These changes typical for reduced lipoprotein lipolysis were due to the formation of a polyarginine-heparin complex, on the one hand, and to the formation of a polyarginine-enzyme complex devoid of the lipolytic properties, on the other. The inhibitory effect of polyarginine on lipoprotein lipase is related to the whole polypeptide molecule or its large fragment, since arginine and metformine (bi-guanidine compound) have no effect on the enzyme activity.

[Comparison of the effect of homologous and heterologous albumin on the activity of lipoprotein lipase and liver triglyceride lipase in rabbit plasma]. / Sravnenie deistviia gomologichnogo i geterologichnogo al'bumina na aktivnost' lipoproteidlipazy i pechenochnoi triglitseridlipazy plazmy krovi krolika.

Changes in the activity of blood plasma lipoprotein lipase (EC 3.1.1.34, LPL and hepatic triacylglycerol lipase EC 3.1.1.3, H-TGL) were studied in rabbits injected intravenously by homologous and heterologous albumins (bovine, fraction Y, Sigma, BSA) alone and in combination with heparin. Rabbit albumin enhanced the effect of heparin on the LPL activity, while heterologous protein, to the contrary, diminished it. The in vitro experiments showed that BSA caused a more distinct effect on the LPL activity as compared with that of rabbit albumin. The activity of H-TGL was not significantly altered under the influence of both proteins.

[Effect of the intravenous administration of homologous albumin on the lipolytic enzyme activity of rabbit blood plasma]. / Vliianie vnutrivennogo vvedeniia gomologichnogo al'bumina na aktivnost' lipoliticheskikh fermentov plazmy krovi krolika.

Activity of main lipolytic enzymes of rabbit blood plasma, lipoprotein lipase (LPL) and liver tissue triglyceride lipase (L-TGL) as well as intensity of lipoprotein lipolysis in vivo, which was estimated by an increase of unesterified fatty acids in blood plasma, studied after intravenous administration of homologous albumin at a dose of 200 mg/kg of body mass. The data obtained suggest that albumin is involved in regulation of lipoprotein lipolysis due to activation of LPL, caused by asseption of unesterified fatty acids, which are liberated after hydrolysis of triglycerides. This effect was exhibited by albumin only under conditions of active stimulation of lipolytic reactions, it occurs after intravenous administration of heparin (100 IU/kg of body mass). Albumin did not activate lipoprotein lipolysis and lipolytic enzymes in intact animals. Activity of L-TGL in blood plasma was less distinctly subjected to the regulatory effect of albumin.

[Role of lipolytic enzymes in the development of hyperlipidemia induced by administration of heterologous albumin in rabbits]. / Uchastie lipoliticheskikh fermentov v razvitii giperlipidemii, vyzvannoi vvedeniem geterologichnogo al'bumina krolikam.

Experiments on rabbits have shown hyperlipidemia to develop within the first 48 h after a single intravenous injection of bovine serum albumin (BSA, fraction V). The mean concentration of blood plasma triglycerides (TG) was considerably higher than normal (by 262% after 24 and by 625% after 48 h). The cholesterol content was also elevated (by 80 and 270%, respectively). Following 7 and 14 days the lipid concentration returned to normal. The plasma post-heparin lipoprotein lipase activity (PHP-LPL) was lower 24 h and 7 days after BSA injection and the hypotriglyceridemic effect of heparin was less pronounced. The data obtained support the hypothesis that hyperlipidemia provoked by a single intravenous injection of BSA to rabbits results from low PHP-LPL activity and possible changes in TG-rich lipoprotein substrate affinity for the enzyme.

[Lipolytic activity in blood plasma of patients with ischemic heart disease after administration of heparin on an empty stomach and with simultaneous fatty loading]. / Lipoliticheskaia aktivnost' plazmy krovi bol'nykh ishemicheskoi bolezn'iu serdtsa pri vvedenii geparina natoshchak i na fone zhirovoi nagruzki.

Effect of heparin on the lipoprotein lipase activity was studied after its administration into fasting and fat loaded patients with heart ischemic disease, exhibiting various lipoprotein spectrum of blood. Heparin activated more distinctly the lipolytic enzymes in the patients kept on fatty diet as compared with the fasting patients. The difference was maximal in the patients with the IIa type of hypolipoproteinemia and minimal--in the patients with the IV type of the disease. The hypotriglyceridemic effect of heparin was found in all the groups examined; however, the least decrease in the triglyceride content occurred in the IV type of hypolipoproteinemia. These data demonstrate the relative deficiency of lipoprotein lipolysis in the type of hypolipoproteinemia studied.

[Blood lipids and lipoproteins in rabbits with experimental allergic polyneuritis]. / Lipidy i lipoproteidy krovi u kroliko v s éksperimental'nym allergicheskim polinevritom.

Experiments were carried out using 69 rabbit males with a body mass of 2.5-3.0 kg. Experimental allergic polyneuritis developed in the animals after administration into foot pads of the base neuritogenic proteins together with complete Freund's adjuvant. Content of cholesterol (CS) and triglycerides (TG) was increased more than 2-fold, concentration of the total fraction of beta- and pre- beta-lipoproteins was elevated 3-fold in blood plasma of rabbits within 1 hr after the treatment. Within 12 days after administration of the mixture another increase in the fractions studied was observed, reaching the maximal value within the 30 days of the experiment: content of cholesterol and triglycerides was increased 3-fold, total fraction beta- and pre- beta-lipoproteins--more than 4-fold. The ratio CS/TG was similar in blood sera of both normal and injured rabbits and was approximately equal to 0.4. The increase in permeability of aortal wall and its lipid infiltration were found at the same period.

[Lipoprotein lipase activity of ischemic heart disease patients with different types of hyperlipoproteinemia on the basis of fat loading]. / Aktivnost' lipoproteidlipazy u bol'nykh ishemicheskoi bolezn'iu serdtsa s razlichnymi tipami giperlipoproteidemii na fone zhirovoi nagruzki.

Lipolytic activity was distinctly increased in blood plasma of patients with ischemic heart impairment and various types of hyperlipoproteinemia after a test breakfast. The increase in lipolysis was due to elevation in the lipoprotein lipase activity in response to loading with lipids. Attempts to distinguish among the ischemic patients some subgroups on the basis only of the initial level of triglycerides in their blood plasma did not exhibit any differences in the enzymatic activity after the loading with lipids. This relationship was clearly noted in classification of the patients on the basis of the types of hyperlipoproteinemia. The earliest and the most pronounced increase in lipolytic activity in response to the loading with lipids was observed in the 11a type of hyperlipoproteinemia.

[alpha-lipoprotein cholesterol and its variability in ischemic heart disease]. / al'fa-lipoproteidnyi kholesterin i ego izmenchivost' u bol'nykh ishemicheskoi bolezn'iu serdtsa.

The authors conducted a repeated examination of 150 patients suffering from ischemic heart disease with normolipidemia and types IIa, IIb and IV hyperlipoproteinemia. The content of alpha-cholesterol in these patients tended to fluctuate, just as the content of other blood lipid fractions. Its fluctuations were most marked in types 11b and IV hyperlipoproteinemia. Comparison of the alpha-cholesterol content in patients with ischemic heart disease with the results of population tests confirmed the information on its lower level in patients. A still greater difference between patients and healthy individuals was revealed when the percentage of total cholesterol for which alpha-lipoproteines accounted and the value of the cholesterol atherogenic index were compared. Reduced concentration of alpha-cholesterol was encountered not only in hyperlipoproteinemia, but also in normolipidemia. The level of alpha-cholesterol had a negative correlative connection with the content of triglycerides in the blood.

[Blood plasma lipolytic enzymes in experimental hyperlipidemia and atherosclerosis in rabbits]. / Lioliticheskie fermenty plazmy krovi pri éksperimental'noi giperlipidemii i ateroskleroze u krolikov.

The activity of blood plasma lipolytic enzymes was studied during the development of experimental hypercholesterolemia and atherosclerosis in rabbits. It is shown that lipoproteinlipase activity in post-heparin blood plasma increases most markedly 6 months after feeding rabbits with cholesterol. The concentration of cholesterol and triglycerides in blood plasma also reaches maximum values in this period. The activity of hepatic triglyceridelipase increases significantly within the same period. In rabbits with experimental atherosclerosis, just as in intact animals, however, the lipolytic activity of post-heparin blood plasma is almost entirely due to lipoproteinlipase.

[Lipid level in the blood, based on multiple study data, and the characteristics of the course of ischemic heart disease]. / Uroven' lipidov v krovi, po dannym mnogokratnogo issledovaniia, i osobennosti techeniia ishemicheskoi bolezni serdtsa.

The blood lipid content and lipoprotein spectrum were repeatedly tested in 216 males with ischemic heart disease for follow-up periods of 4 to 5 years. Irrespective of the type of hyperlipoproteinemia, the blood triglyceride level was marked by the greatest individual fluctuations and the level of total cholesterol by the least fluctuations. Comparison of the clinical course of ischemic heart disease with the peculiarities of the changes in the blood lipid content revealed a higher incidence of recurrent myocardial infarction and sudden death among individuals with type IIa hyperlipoproteinemia. Recurrent vascular catastrophes were observed not only in patients with stable hypercholesterolemia but also in individuals with its labile form. It is concluded that repeated tests for the blood lipid content provide for more reliable diagnosis of hyperlipidemia and the type of hyperlipoproteinemia, which is of unquestionable practical importance.

[Activity of postheparin lipoprotein lipase in rabbit blood plasma]. / Aktivnost' postgeparinovoi lipoproteidlipazy plazmy krovi krolikov.

Activity of lipoprotein lipase was studied in rabbit blood plasma after administration of heparin at a dose 50 un/kg into animals. NaCl was added to incubation mixture at final concentration 1 M to differentiate the enzyme from liver triglyceride lipase. The salt inhibited strongly (sometimes completely) the lipolytic activity in rabbit postheparin blood plasma. These data suggest predominance of lipoprotein lipase, sensitive to NaCl, in total lipolytic activity of rabbit postheparin blood plasma. Only slight alterations in the value of total lipolytic activity and in activity, depending on lipoprotein lipase, were observed in rabbits maintained at high cholesterol diet. Under these conditions distinct increase in activity of triglyceride lipase, stable to NaCl , was not found.