Effect of tetracaine on thrombocyte aggregation and mobilization of the intracellular calcium

Tetracaine (1 mM), a local anesthetics, lowers a degree of aggregation of human thrombocytes which is induced by thrombin (0.15 u/ml) and suppresses its appearance. Aggregation of thrombocytes induced by phorbol ester, TPA (10-8 M), an activator of protein kinase C, is inhibited completely by the mentioned doses of the anesthetics. In the presence of tetracaine the release of intracellular Ca is lower to some extent, but then it surpasses the control level. It is established that under the action of ionophore A23187 tetracaine exerts no effect on mobilization of intracellular Ca2+.     

The effect of stabilizer composition on thrombocytes and thrombocyte function in stored whole blood. I. The thrombocyte count, thrombocyte aggregation and retraction during storage]

The behaviour of thrombocyte number and thrombocyte function aggregation and retraction in ACD, AcD-A and AcD-AG stabilized blood was examined in 18 apparently healthy test persons for a period of 9 days. On the one hand the addition of adenin or guanosin respectively increased the thrombocyte aggregation, on the other hand, however, a decrease of free, haemostatically efficient thrombocytes could be observed. Under the test conditions chosen retraction does not allow any statement to be made on the degree of the storage damage.     

Turnover of the amino sugars of erythrocyte and thrombocyte glycoproteins in rats maintained on different carbohydrate diets

The turnover of erythrocyte and platelet glycoprotein amino sugars in rats fed carbohydrates has been studied. Partial replacement of starch by sucrose results in an almost 3-fold increase in the half-life of erythrocyte glycoprotein amino sugars and in a 2-fold increase in that of platelets as early as 14 days after keeping the animals on carbohydrates. It is concluded that study of dynamic parameters of cell amino sugars can be used for evaluation of the role played by food in metabolic and adaptive reactions both in experimental animals and man.     

Zinc deficiency and the desaturation of linoleic acid in rats force-fed fat-free diets

Recent studies with rats force-fed zinc-deficient diets containing various types of fat failed to demonstrate a role of zinc in desaturation of linoleic acid. The present study was conducted to investigate the effect of zinc deficiency on desaturation of linoleic acid in rats that were initially force-fed fat-free diets to stimulate activity of desaturases. Therefore, rats were fed zinc-adequate and zinc-deficient fat-free diets for 6 d. After that period, the groups were divided and half of the rats continued feeding the fat-free diet for another 3.5 d whereas the other half was switched to a fat diet by supplementing the fat-free diet with 5% safflower oil. In order to assess desaturation of linoleic acid, fatty acid compositions of liver phosphatidylcholine, ethanolamine, and-serine were considered, particularly levels of individual (n-6) polyunsaturated fatty acids (PUFA). Levels of total and individual (n-6) PUFA were similar in zinc-adequate and zinc-deficient rats fed the fat-free diet throughout the experiment. Addition of 5% safflower oil increased levels of total and individual (n-6) PUFA in both zinc-adequate and zinc-deficient rats. However, total (n-6) PUFA in all types of phospholipids were higher in zinc-adequate rats than in zinc-deficient rats. Additionally, in zinc-deficient rats there were changes of (n-6) PUFA levels typical for impaired Δ5 and Δ6 desaturation: linoleic acid and dihomo-γ-linolenic acid were elevated; arachidonic acid, docosatetraenoic acid, and docosapentaenoic were lowered by zinc deficiency. Therefore, the study shows that zinc deficiency impairs desaturation of linoleic acid in rats force-fed fat-free diets and therefore supports results from former convential zinc deficiency experiments suggesting a role of zinc for desaturation of linoleic acid.     

Effect of serine proteinases on the intracellular dynamics of membrane lipids and aggregation of human thrombocytes

Room temperature tryptophan phosphorescence (RTTP) of human platelets in suspension was studied. The spectral and kinetic parameters of RTTP of thrombocytes were determined. By using the RTTP, the effect of serine proteases: thrombin, trypsin, and alpha-chymotrypsin at low concentrations (0-50 micrograms/ml) on the slow internal dynamics of membrane proteins was studied. It was shown that short-term incubation of platelets with proteases induces changes in the internal dynamics of membrane proteins in situ, and the magnitude of this effect correlates well with the extent of platelet aggregation. The functional role of the changes in the internal dynamics of membrane proteins and their relationship with intracellular signal transduction were discussed.     

Effect of CO2 on thrombocyte aggregation in the cat

The antiaggregation ability of CO2 during ADP- and collagen-induced platelet aggregation has been discovered in cats under hypercapnia. The effect persisted after Pco2 normalization. The inhibition of cyclooxygenase by indomethacin suppressed the antiaggregation activity of CO2 in vivo but not in vitro. While estimating the regulatory role of CO2 in the metabolic control of cerebral circulation, it is also of importance to take into account the antiaggregation ability of CO2.     

Substituting dietary linoleic acid with alpha-linolenic acid improves insulin sensitivity in sucrose fed rats

This study describes the effect of substituting dietary linoleic acid (18:2 n-6) with alpha-linolenic acid (18:3 n-3) on sucrose-induced insulin resistance (IR). Wistar NIN male weanling rats were fed casein based diet containing 22 energy percent (en%) fat with approximately 6, 9 and 7 en% saturated fatty acids (SFA), monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) respectively for 3 months. IR was induced by replacing starch (ST) with sucrose (SU). Blends of groundnut, palmolein, and linseed oil in different proportions furnished the following levels of 18:3 n-3 (g/100 g diet) and 18:2 n-6/18:3 n-3 ratios respectively: ST-220 (0.014, 220), SU-220 (0.014, 220), SU-50 (0.06, 50), SU-10 (0.27, 10) and SU-2 (1.1, 2). The results showed IR in the sucrose fed group (SU-220) as evidenced by increase in fasting plasma insulin and area under the curve (AUC) of insulin in response to oral glucose load. In SU-220, the increase in adipocyte plasma membrane cholesterol/phospholipid ratio was associated with a decrease in fluidity, insulin stimulated glucose transport, antilipolytic effect of insulin and increase in basal and norepinephrine stimulated lipolysis in adipocytes. In SU-50, sucrose induced alterations in adipocyte lipolysis and antilipolysis were normalized. However, in SU-2, partial corrections in plasma insulin, AUC of insulin and adipocyte insulin stimulated glucose transport were observed. Further, plasma triglycerides and cholesterol decreased in SU-2. In diaphragm phospholipids, the observed dose dependent increase in long chain (LC) n-3 PUFA was associated with a decrease in LC-n-6 PUFA but insulin stimulated glucose transport increased only in SU-2. Thus, this study shows that the substitution of one-third of dietary 18:2 n-6 with 18:3 n-3 (SU-2) results in lowered blood lipid levels and increases peripheral insulin sensitivity, possibly due to the resulting high LCn-3 PUFA levels in target tissues of insulin action. These findings suggest a role for 18:3 n-3 in the prevention of insulin resistant states. The current recommendation to increase 18:3 n-3 intake for reducing cardiovascular risk may also be beneficial for preventing IR in humans.     

The radioisotope labelling of thrombocytes using a monoclonal antibody against membrane glycoproteins IIb-IIIa and the measurement of thrombocyte adhesion/aggregation on the substrate surface]

A new method for platelet labeling based on binding of monoclonal antibody to human platelets has been suggested in this study. Monoclonal antibody VM16a against membrane glycoproteins IIb-IIIa was labeled by 125I and then incubated with platelets. About 70% of added antibody was bound when it was used at the concentrations corresponding to the linear part of the concentration curve (0.5 and 1.0 micrograms/ml). Due to high efficiency of binding 125I-VM16a-labeled platelets were used for the measurement of adhesion/aggregation to the substrate in platelet-rich plasma without washing of the free label. Experiments with washed platelets double labeled with 51Cr and 125I-VM 6a showed high correlation between the data obtained with both labels. The method of platelet labeling has been applied for the assessment of drug action on platelet adhesion/aggregation. Measurements were performed in platelet-rich plasma and adhesion/aggregation was stimulated by ADP and analogue of thromboxane A2, U46619. It was shown/that antianginal drug trapidil strongly inhibited and antiatherogenic drug probucol did not affect platelet adhesion/aggregation stimulated by both agonists.     

Effect of phospholipase A on erythrocyte and thrombocyte aggregation]

A study was made of the effect of plasmin and trypsin on the phospholipase activation, and also of the action of phospholipase A (cobra venom) on the release reaction and the erythrocyte and thrombocyte aggregation. Trypsin and fibrinolysin proved to activate phospholipase, this being accompanied by the accumulation of nonesterified fatty acids in the blood serum. Phospholipase A caused a release of the thromboplastic factor from erythrocytes and thrombocytes and their aggregation. The later is inhibited by albumin and EDTA. It is suggested that the action of the proteolytic enzymes on the blood formed elements was realized through the phospholipase activation.     

The effect of linoleic acid on the sensitivity of human lymphocytes to cortisol and their capacity to catabolize the steroid

We have shown previously that cortisol-sensitive lymphocytes (thymocytes) have a much lower capacity than cortisol-resistant cells to catabolize cortisol. In the present study, we attempt to demonstrate that inhibition of cortisol catabolism may make cortisol-resistant lymphocytes vulnerable to the steroid. Linoleic acid, which has the capacity to inhibit the catabolism of cortisol by lymphocytes, was used for this purpose. By using various concentrations of linoleic acid (20-60 micrograms/mL) we showed an inverse linear relationship between linoleic acid concentration and the rate of cortisol catabolism by lymphocytes. During this experiment which took 17 h the viability of cells did not change significantly (minimum viability 95%), even at the highest concentration of linoleic acid. Keeping the metabolism of cortisol at a level of 40% of that obtained by the control, by adding linoleic acid to lymphocyte cultures (50 micrograms/mL) and measuring the viability of the cells for a period of 3 days in the presence or absence of cortisol, we were able to show a rise in the death rate of the cells which started after 24 h of incubation owing to the presence of the steroid.     

Effect of ethanol on the levels of dopamine and its metabolites in the brain of rats with different degree of sensitivity to stress

It was shown, that content of dopamine and its metabolites (DOPAC and HVA) are the same in two groups of rats with different time of immobilization in forced swimming test. One group of low active (LA) animals experienced the immobilization more than 300s, other high active (HA) rats for less than 120 s. Ethanol (2 g/kg per oris) increased the level of DA in the striatum and medial prefrontal cortex only in LA rats and besides, the concentration of dopamine after ethanol administration was higher in the n. accumbens of LA rats, than in that of HA rats. The authors suggest that differences in dopamine content between LA and HA rats are connected with different levels of voluntary alcohol consumption. The opportunity to use both groups of HA and LA rats for developing models of pathogenic heterogeneity of alcoholism is discussed.     

Effect of diets supplemented with different conjugated linoleic acid (CLA) isomers on protein expression in C57/BL6 mice

Background

The individual genetic variations, as a response to diet, have recently caught the attention of several researchers. In addition, there is also a trend to assume food containing beneficial substances, or to supplement food with specific compounds. Among these, there is the conjugated linoleic acid (CLA), which has been demonstrated to reduce fat mass and to increase lean mass, even though its mechanism of action is still not known. We investigated the effect of CLA isomers (CLA c9,t11 and CLA t10,c12) on the proteomic profile of liver, adipose tissue, and muscle of mouse, with the aim of verifying the presence of a modification in fat and lean mass, and to explore the mechanism of action.

Methods

C57/BL6 mice were fed for 2 months with different diets: (1) standard chow, (2) CLA c9,t11 diet, (3) CLA t10,c11 diet, (4) CLA isomers mixture diet, and (5) linoleic acid diet. The proteomic profile of liver, white adipose tissue, and muscle was investigated. Statistical significance of the spots with an intensity higher than twofold in expression compared to the control was tested using student’s t test (two-tail).

Results

We found that both isomers modulate the proteomic profiles of liver, adipose tissue, and muscle by different mechanisms of action. Liver steatosis is mostly due to the isomer CLA t10,c12, since it alters the expression of lipogenetic proteins; it acts also reducing the adipose tissue and increasing fatty acid oxidation in muscle. Conversely, CLA c9,t11 has no relevant effects on liver and adipose tissue, but acts mostly on muscle, where it enhances muscular cell differentiation.

Conclusions

Administration of CLA in humans has to be carefully personalized, since even considering the presence of a species-specific effect, adverse effects might occur on long-term supplementation. Here we demonstrated that, in mouse, CLA is effective in reducing fat mass, but it also induces liver steatosis. The increase of lean mass is linked to an induction of cell proliferation, which, on long-term supplementation, might also lead to adverse effects.

     

Cyclic nucleotides, prostaglandins and thrombocyte aggregation in rats poisoned with "murine" Yersinia pestis toxin

Y. pestis "mouse" toxin, introduced intraperitoneally into rats in a dose of LD100 [correction of LG100], produces phasic changes in the thrombin-induced aggregation of thrombocytes and the content of prostaglandins and cyclic nucleotides in them. As the result of the damaging action on the endothelium of blood vessels at the initial period of intoxication, the concentration of prostaglandin 6-keto F1 alpha in blood plasma and cAMP [correction of cAMR] in thrombocytes sharply decreases, which causes the enhancement of thrombin-induced cell aggregation. At a later period the level of prostaglandin E in the cells sharply rises. At later irreversible stages of shock, induced in the cells of Y. pestis "mouse" toxin, the content of cGMP in cells sharply increases, which leads to the development of the phase of thrombocyte hypoaggregation.     

Fish oil reduces cholesterol and arachidonic acid content more efficiently in rats fed diets containing low linoleic acid to saturated fatty acid ratios

Rats were fed diets containing a high level of saturated fatty acids (hydrogenated beef tallow) versus a high level of linoleic acid (safflower oil) at both low and high levels of fish oil containing 7.5% (w/w) eicosapentaenoic and 2.5% (w/w) docosahexaenoic acids for a period of 28 days. The effect of feeding these diets on the cholesterol content and fatty acid composition of serum and liver lipids was examined. Feeding diets high in fish oil with safflower oil decreased the cholesterol content of rat serum, whereas feeding fish oil had no significant effect on the cholesterol content of serum when fed in combination with saturated fatty acids. The serum cholesterol level was higher in animals fed safflower oil compared to animals fed saturated fat without fish oil. Consumption of fish oil lowered the cholesterol content of liver tissue regardless of the dietary fat fed. Feeding diets containing fish oil reduced the arachidonic acid content of rat serum and liver lipid fractions, the decrease being more pronounced when fish oil was fed in combination with hydrogenated beef tallow than with safflower oil. These results suggest that dietary n-3 fatty acids of fish oil interact with dietary linoleic acid and saturated fatty acids differently to modulate enzymes of cholesterol and fatty acid metabolism.     

Fatty acid composition and conjugated linoleic acid content of different tissues in rats fed individual conjugated linoleic acid isomers given as triacylglycerols small star,filled

HEAT TREATMENT OF VEGETABLE OILS GAVE RISE TO FOUR MAIN CONJUGATED LINOLEIC ACID (CLA) ISOMERS : the 9c,11t, 9t,11t, 10t,12c and 10t,12t. The diet of male Wistar rats was supplemented with 150 mg/day either 9c,11t-, 9t,11t-, 10t,12c- or 10t,12t CLA isomers for 6 days and their effects on lipid composition were investigated in liver, heart, skeletal muscle Gastrocnemius, kidneys, brain and adipose tissue. The incorporation of all isomers was low (< 1.4%) and the level was as follows : adipose tissue > Gastrocnemius > liver, kidneys > brain. The main changes in the overall lipid composition were observed in skeletal muscle (Gastrocnemius) and in heart and were associated with feeding the 10t,12c and 10t,12t isomers. The diet enriched in 10t,12t CLA decreased the total long chain polyunsaturated fatty acid proportion in Gastrocnemius (from 18.4% to 14.4%) and increased that of 20:4 n-6 in heart (from 16.9 to 19.3%). The diet enriched in 10t,12c CLA decreased the monounsaturated fatty acid proportion in Gastrocnemius (from 32.0 to 26.1%) and produced an effect similar to the 10t,12t in heart. By contrast, the 9c,11t and 9t,11t isomers did not affect fatty acid composition in all tissues and organs. We concluded that ingestion of 10t,12c and 10t,12t CLA present in oils and in CLA mixtures could change muscle lipid composition.