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Biomedical subjects

E Tremoli

Publications and source records attributed to E Tremoli.

At least 145 records · Page 8Linked to original sources
PubMed1980

New strategies in the development of anti-atherosclerotic drugs.

The results of several recently completed trials of cardiovascular prevention, by the use of hypolipidemic or anti-platelet compounds, have suggested that new strategies be followed for the development of anti-atherosclerotic drugs. The final outcome of preventive studies with hypolipidemic compounds is markedly influenced by the significance of the achieve hypolipidemia, as well as by the side-effects, some which, i.e. lithogenicity, may be related to the drugs' mechanism of action. Significant differences may, moreover, exist between the findings in animal models and in humans, particularly by clofibrate and related compounds. The evaluation of drugs active on lipoprotein biosynthesis in the gut (metformin), potent enzyme inhibitors (compactin) and with chelating activity (cetaben), is awaited with interest. In the field of drugs affected platelets, a selective sensitivity for the major compounds in different vascular areas has been observed. Aspirin appears to be mostly effective in cerebro-vascular prevention. Agents affecting the thrombin-platelet coagulation interaction, i.e. GYKI 14,451, may offer an interesting opportunity for testing the importance of this pathway in clinical thrombosis.

4-Aminobenzoic Acid↗
PubMed1979

Indobufen (K 3920), a new inhibitor of platelet aggregation: effect of food on bioavailability, pharmacokinetic and pharmacodynamic study during repeated oral administration to man.

The effect of food on bioavailability of indobufen tablets was investigated in 6 healthy volunteers. Subsequently, the same subjects took 100 mg b.i.d. for 7 days. Plasma levels and urinary excretion of indobufen were determined by GLC. Platelet aggregation induced by several concentrations of adrenaline was determined turbidimetrically at various times after the first and last doses. The absorption of indobufen tablets was not substantially impaired by the presence of food in the GI tract, although peak plasma levels and AUCs were slightly reduced after food. Pharmacokinetic analysis of plasma and urinary levels of indobufen did not indicate any change in drug disposition after repeated dosing. Adrenaline-induced platelet aggregation was markedly inhibited for up to 12 h after the first dose and the intensity and duration of this effect did not change after repeated administration. A twice-daily dosing appears suitable for clinical trials.

Adult↗
PubMed1979

Early increase of a new platelet coagulant activity in rats fed a thrombogenic diet.

A recently described platelet coagulant activity (factor X activating activity), whose pathophysiological significance is as yet unknown, was studied in rats fed a fat-rich (thrombogenic) diet for 1, 2 and 7 weeks and compared to rats fed normal laboratory chow. Whatever the duration of the special feeding period, a highly significant shortening of the clotting time, used for measuring this activity, was observed. When the platelet coagulant activity of individual "fat-fed"rats was quantitated by reference to that of individual control animals, we found a mean increase of 350% (n = 9) after one week and 267% (n = 3) after two weeks of dietary treatment. Partial thromboplastin time, thrombin time and soluble fibrin monomer complexes did not differ in control and treated animals. It seems that platelet coagulant activity, as measured in our test system, is one of the first laboratory parameters to be modified by fat-rich diets. These findings may be relevant to an understanding of the role of platelet coagulant activities other than platelet factor 3 in thrombotic phenomena.

Animals↗
PubMed1979

Clinical experience with the soybean protein diet in the treatment of hypercholesterolemia.

The efficacy of the total substitution of animal proteins with a textured soybean protein in hypercholesterolemic individuals was assayed in 42 in-patients and 18 out-patients. The in-patients studied followed one of three different crossover protocols: in protocol A, the soybean diet was compared with a standard low lipid diet; protocol B compared two soybean diets, one with added cholesterol, one without; and protocol C compared a soybean diet containing a high P/S fatty acid ratio to one with a low P/S ratio. In all three protocols, the soybean regimen provided valid and reproducible hypocholesterolemic effects that were not modified by the addition of cholesterol. P/S variations appeared, however, to modify the final effect: soybean definitely had a decreased effectiveness with a low P/S (0.1) regimen. The overall plasma cholesterol changes in the 42 in-patients after 3 weeks on the different soybean diet protocols was -20%. Patients with type IIA and IIB hypercholesterolemia provided almost equivalent results, whereas patients with mixed phenotypes (IIB-III) appeared somewhat more sensitive to the dietary effect. Cholesterol decreased mostly in the low density lipoprotein fraction, but some very low density lipoprotein changes were also noted upon variation of the P/S ratio. The out-patients studied provided less satisfactory results. possibly due to the difficulty of adequately complying with the diet. These studies indicate that treatment with the soybean diet is an effective regimen for inducing a significant cholesterol reduction in type II patients refractory to standard low lipid regimens.

Adult↗
PubMed1979

Platelet aggreation malondialdehyde formation in type IIA hypercholesterolemic patients.

Platelet aggregation induced by threshold concentrations of ADP, adrenaline, collagen and Thrombofax was evaluated in 25 type IIA hypercholesterolemic patients in comparison with 15 control subjects. Malondialdehyde (MDA) formation induced by collagen and thrombin was also studied in a subgroup of 8 patients. In the patient group, irreversible platelet aggregation was induced by significantly lower concentrations of both adrenaline (p is less than 0.05) and Thrombofax (p is less than 0.01). MDA formation induced by both aggregating agents was markedly increased (p is less than 0.01) in type IIA hypercholesterolemic patients.

Adult↗
PubMed1978

Influence of short term dietary supplementation of different lipids on aggregation and arachidonic acid metabolism in rabbit platelets.

Semisynthetic diets containing 8% by weight of either corn oil or butter were fed to male New Zealand rabbits for three weeks. The plasma cholesterol values were determined, the threshold concentrations for aggregation of platelet rich plasmas were measured for collagen and Na arachidonate, and the conversion of 14C arachidonic acid to thromboxane B2 and hydroxy fatty acids (HETE and HHT) at 10, 20 and 40 microM substrate concentrations were studied. The thresholds for arachidonate induced aggregation were lower and the amplitudes of collagen induced aggregations were greater in the butter fed than in the corn oil fed rabbits. Conversions of arachidonic acid to thromboxane B2 but not to hydroxy fatty acids were greater in the butter fed rabbits at 10 and 20 microM substrate. The observed changes were accompanied by only slight modifications of plasma cholesterol levels.

Animals↗
PubMed1977

Treatment of hypertriglyceridemia with metformin. Effectiveness and analỳsis of results.

The triglyceride-lowering effect of metformin (N,N-dimethylbiguanide) was tested in a series of patients with stable hypertriglyceridemia (types IIB, III and IV) and with variable degrees of glucose intolerance. Metformin caused a 38% mean decrease of plasma triglycerides. A selective decrease of very low density lipoprotein cholesterol was observed without reciprocal increase of low density lipoproteins. Thirty patients completed the study. Eighteen, who showed a hypotriglyceridemic effect exceeding 30%, were considered as "Responders"; the other 12, where the effect was negligible, were considered as "Non-Responder". Analysis of the pre-and post-treatment glucose tolerance tests of Responders and Non-Responders showed that the former had, on the average, a normal glucose tolerance and insulin secretion, whereas the latter had an impaired glucose tolerance with increased insulin secretion. These parameters were only slightly modified by metformin. The conclusions of this study support the hypothesis that biguanides exert a triglyceride-lowering effect by decreasing lipoprotein secretion, independent of changes in glucose tolerance and/or insulin secretion.

Adult↗
PubMedDate not supplied

5-Lipoxygenase gene expression in HL60 cells during differentiation with DMSO.

The model of promyelocytic leukemia cells HL60 was utilized to study the accumulation of 5-lipoxygenase mRNA during the cellular differentiation induced by DMSO. In the present study a strict correlation between the increase in state of differentiation of HL60 and accumulation of 5-lipoxygenase mRNA is demonstrated, indicating that HL60 cells are an interesting model for the study of drugs which could interfere with the synthesis of the enzyme.

Arachidonate 5-Lipoxygenase↗
PubMedDate not supplied

Effects of coffee on plasma lipids, lipoproteins and apolipoproteins.

The acute effects of coffee, cigarette smoking and alcohol on serum lipids, lipoproteins and thromboxane B2 production by platelets were studied in nine healthy volunteers who were non-drinkers of coffee and alcohol and non-smokers. They received, in a single administration, coffee (containing 200 mg of caffeine), alcohol (0.50 ml/kg body wt), or smoked two cigarettes. No differences were observed between baseline and 15, 60 and 80 min values for plasma cholesterol, triglycerides, HDL cholesterol, plasma apolipoproteins A-I and B and thromboxane B2 production. Chronic coffee consumption also did not affect either plasma lipoprotein profile or the interaction of low density lipoproteins with cellular receptors in a group of healthy individuals. These results suggest that coffee itself does not affect acutely the plasma lipoprotein profile in healthy man. This was also true in heavy coffee drinkers.

Adult↗
PubMedDate not supplied

Oxidized LDLs influence thrombotic response and cyclooxygenase 2.

Oxidative modification of low-density lipoproteins (LDLs) plays a key role in the development of atherosclerosis and the onset of coronary artery disease. LDL oxidation alters the antithrombotic balance of human endothelial cells inducing surface tissue factor (TF) pathway activity, which results in enhanced fibrin deposition. Fibrinolysis, which is strictly regulated by plasminogen activator inhibitor-1 (PAL-1) and tissue-type plasminogen activator (tPA). Is also dysregulated by LDL oxidation with a net increase in the inhibitory rate. Oxidized LDLs (oxLDLs) also affect many aspects of macrophage function linked to the inflammatory response of these cells, In particular, oxLDLs downregulate inducible cyclooxigenase (Cox-2) in human monocyte-derived macrophages exposed to bacterial lipopolysaccharide. This observation may support the hypothesis that, within atheromata, the transformation macrophages into foam cells results in the attenuation of the inflammatory response, thus contributing to the progression of athrogenesis. Among lipid constituents of oxLDLs, Ox-PAPC, a mixture of oxidized arachidonic acid-containing phospholipids, prevents Cox-2 expression, suggesting that it could be considered responsible for the biological activity of oxLDLs.

Arteriosclerosis↗
PubMedDate not supplied

Age- and gender-related oxidative status determined in healthy subjects by means of OXY-SCORE, a potential new comprehensive index.

Oxidative stress has been related to various diseases, gender and ageing, and has been measured by various markers. The authors developed a procedure to compute a global oxidative stress index (OXY-SCORE), reflecting both oxidative and antioxidant markers in healthy subjects. Its performance was tested in relation to age and gender and in coronary artery disease (CAD) patients. Eighty-two healthy subjects and 20 CAD patients were enrolled. Plasma free and total malondialdehyde (F- and T-MDA), glutathione disulphide/reduced form ratio (GSSG/GSH) and urine isoprostanes (iPF2alpha-III) levels were combined as oxidative damage markers (damage score). GSH, alpha- and gamma-tocopherol (TH) levels, and individual antioxidant capacity were combined as antioxidant defence indexes (protection score). The OXY-SCORE was computed by subtracting the protection score from the damage score. Among single parameters, T-MDA and iPF2alpha-III significantly correlated with age; only GSH and both tocopherols correlated with male gender in healthy subjects. The OXY-SCORE was positively associated with age (p=0.004) and male gender (p=0.03). As expected, the OXY-SCORE was higher in CAD with a very significant p-value (<0.0001), after adjusting for age, gender and smoking. Combining different markers can potentially provide a powerful index in the evaluation of oxidative stress related to age, gender and CAD status.

Adult↗