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Biomedical subjects

J Beitz

Publications and source records attributed to J Beitz.

At least 55 records · Page 3Linked to original sources
PubMed1987

[Decreasing atherogenic risks by an eicosapentaenoic acid-rich diet].

(n-3) diets rich in polyunsaturated fatty acids (PUFA) reduce the atherogenic lipoproteins, especially the VLDL (very low density lipoproteins) rich in triglycerides but also the LDL, more effectively than (n-6) PUFA-rich diets. Moreover also other parameters such as high blood pressure and aggregation of thrombocytes are positively influenced, similarly like after (n-6) PUFA-rich diet. Eicosapentaenoic acid (20:5, n-3) has a triglyceride- and cholesterol-reducing effect by inhibition of the VLDL-synthesis (apolipoprotein B, triglycerides) in the liver, inhibition of lipogenic liver enzymes, accelerated elimination of VLDL from the circulation, increased excretion of steroids and bile acids into the stools and amelioration of the fat tolerance. The prolongation of the period of haemorrhage and the decrease of the aggregation of thrombocytes is associated with the enrichment of EPA in the platelet membrane. In these cases the decreased thrombocyte-vascular vessel-interaction shall be caused by a changed metabolism of the eicosanoids (secondary products of unsaturated fatty acids with 20 carbon atoms) and eicosanoid-independent mechanisms.

Arteriosclerosis↗
PubMed1987

Do endogenous lipoproteins modulate the sensibility of animals against arrhythmogenic drugs?

The present study suggests that a diminished level of HDL is connected with an enhanced susceptibility to arrhythmogenic stimuli only in rats pretreated with a diet deficient in polyunsaturated fatty acids (PUFA), but not after a PUFA-rich or pellet diet. The endogenous level of total cholesterol did not influence the thresholds for ventricular flutter or ventricular fibrillation in aconitine-induced arrhythmia in rats or in ouabain-induced arrhythmia in guinea pigs.

Aconitine↗
PubMed1987

The influence of cod-liver oil diet on various lipid metabolism parameters, the thromboxane formation capacity, platelet function and the serum MDA level in patients suffering from myocardial infarction.

The influence of an eicosapentaenoic-acid-rich diet, containing 8.1 g cod-liver oil, given daily for two weeks on various parameters of lipid metabolism, the thromboxane formation capacity, platelet function and the serum MDA level was studied in 16 patients with myocardial infarction. The 18:2, 20:3 and 20:4 fatty acid portions of serum phospholipids were significantly decreased, whereas the 20:5 and 22:6 portions were significantly elevated. Serum total cholesterol, LDL cholesterol and the thromboxane formation capacity were significantly increased. Serum triglycerides, HDL cholesterol, the prostacyclin blocking activity of LDL, and several parameters of platelet function were unchanged, the platelet count was significantly depressed. As compared to those of healthy persons, the serum MDA levels in myocardial infarction patients were significantly increased both before and after cod-liver oil ingestion. A possible correlation between the elevated serum levels of MDA and total cholesterol, LDL cholesterol as well as thromboxane formation capacity and the cod-liver oil treatment in patients with myocardial infarction is discussed.

Cholesterol↗
PubMed1986

Influence of a cod liver oil diet in healthy and insulin-dependent diabetic volunteers on fatty acid pattern, inhibition of prostacyclin formation by low density lipoprotein (LDL) and platelet thromboxane.

Ten healthy and twenty diabetic volunteers (type 1) received 15 capsules (à 450 mg) cod liver oil for 2 weeks daily in addition to a "normal" diet. The levels of eicosapentaenoic acid in the plasma phospholipids of both groups were increased after the treatment. The inhibition of the prostacyclin formation by LDL was diminished when the LDL was isolated after the treatment in comparison to LDL taken in the same concentration and from the same donors before it. The thromboxane B2 (TXB2) synthesis capacity of clotting whole blood, thrombin-induced TXB2 formation by platelets as well as the 15(S)-hydroxy-11 alpha,9 alpha-epoxymethano-5Z, 13E-prostadienoic acid-induced platelet aggregation were not altered by the treatment in healthy volunteers, whereas in diabetics the TXB2 formation capacity of clotting whole blood was decreased after the treatment in comparison with before it.

Adult↗
PubMed1986

[Significance of eicosanoids for arteriosclerosis and the effect of lipoproteins on prostanoid formation].

In a review the possible relevance of the eicosanoid system for arteriosclerosis is outlined. Particularly the interdependence between prostacyclin and thromboxane regarding the development of arteriosclerosis is discussed. Own findings show the influence of lipoproteins on the synthesis of prostacyclin or thromboxane in different biological material. On the one hand, HDL stimulates the synthesis of prostacyclin, whereas LDL inhibits it; both of them were sampled from human volunteers. On the other hand, the synthesis of thromboxane is inhibited by HDL and stimulated by LDL. The results indicate the close relationship between the lipoprotein and the eicosanoid hypotheses of arteriosclerosis.

Animals↗
PubMed1986

Comparative study of the blood pressure effects of four different vegetable fats on young, spontaneously hypertensive rats.

Following the suckling period, four groups of male four-week-old spontaneously hypertensive rats (SHR) were fed semisynthetic diets with 14% (by weight) of either sunflower seed oil [46% 18:2(n-6); linoleic acid (LA)-rich], linseed oil [62.5% 18:3(n-3) + 12.9% 18:2(n-6); alpha-linolenic acid (LNA)-rich], evening primrose oil [9.2% 18:3(n-6) + 71% 18:2(n-6); gamma-linolenic acid (LNA)-rich] or hydrogenated palm kernel fat [1.5% 18:2(n-6); polyunsaturated fatty acid (PUFA)-deficient], respectively, up to an age of 18 wk. All diets enriched with PUFA provoked an attenuation of hypertension development. The effect was lowest in the LA-rich group and highest in the gamma-LNA-rich group. Differences in fatty acid composition of renal phospholipids between groups reflect the fatty acids present in the respective dietary fats. Renomedullary production of PGF2 alpha was significantly reduced in alpha-LNA-rich and slightly diminished in gamma-LNA-rich fed rats. Aortic formation of 6-keto-PGF1 alpha and TXB2 was increased in animals fed the gamma-LNA-rich diet. Thus, the attenuation of hypertension development cannot be explained only by changes in prostanoid formation. Other mechanisms possibly involved should be pursued.

Animals↗
PubMed1986

Endogenous lipoproteins modify the thromboxane formation capacity of platelets.

A significantly negative correlation was demonstrated between HDL-cholesterol levels of serum and the thromboxane B2 (TXB2) formation in clotted whole blood, whereas a significantly positive correlation was estimated between the LDL cholesterol or apolipoprotein B (apo B) levels and the TXB2 formation in clotted whole blood. Similar relationships were observed between the HDL and apo B serum levels and the thrombin-induced malondialdehyde formation in platelet-rich plasma. The levels of HDL2 cholesterol, total cholesterol, apo A-I and of triglycerides were not significantly correlated with the TXB2 or malondialdehyde formation in both systems. The results in this study support the hypothesis that the TXB2 formation may be modulated by endogenous lipoproteins: high level of LDL stimulates and high level of HDL inhibits the TXB2 formation.

Adult↗
PubMed1986

Serum triglycerides and HDL cholesterol from SHR after evening primrose oil and other polyunsaturated fats.

Spontaneously hypertensive rats (SHR) were fed diets enriched with evening primrose (EPO), sunflower (SO) and linseed oils (LO) as well as palm kernel fat (PKF), the latter being deficient in polyunsarated fatty acids (PUFA). In SHR fed EPO serum triglycerides were lowest and HDL1 cholesterol was highest as compared to the other groups of animals. Total cholesterol was not different. The data suggest that - as with blood pressure - serum lipids and lipoproteins might be influenced most effectively by EPO in comparison to other polyunsaturated fats.

Administration, Oral↗
PubMed1986

The influence of lipoproteins (LDL and HDL) on PGI2-formation by isolated aortic preparations of rabbits.

The influence of LDL- and HDL-concentrations of 0.5-2.0 mg/ml and 0.25-1.0 mg/ml respectively, from male and female donors on the formation of PGI2 in isolated aortic preparations was investigated under in vitro conditions. LDL of male donors inhibited endogenous PGI2-formation and the conversion of exogenous PBH2 to PGI2. On the other hand the highest concentration of HDL induced an increase in the basal and in the stimulated PGI2-formation. Lipoproteins of female donors showed no or only a weak stimulating effect on PGI2-formation. Human serum albumin in comparable concentrations of 1-50 mg/ml remained without influence. The importance of the results for cardiovascular diseases is discussed.

Animals↗
PubMed1986

Thromboxane A2 (TXA2) formation by washed human platelets under the influence of low and high density lipoproteins from healthy donors.

Low density lipoprotein (LDL) stimulates TXA2 formation (measured as malondialdehyde) in washed human platelets with active cyclooxygenase, whereas high density lipoprotein (HDL) does not show any influence on TXA2 formation in this system. These results support the hypothesis that the proaggregatory action of a high plasma LDL concentration may be mediated by modification in the biosynthesis of eicosanoids. The mode of action of lipoproteins is discussed.

Blood Platelets↗
PubMed1986

Cardiovascular actions of dihydralazine as modified by dietary linoleic acid.

The experiments were carried out in order to examine whether the hypotensive effect of dihydralazine can be augmented by concomitant ingestion of a diet enriched with linoleic acid. After prefeeding with a linoleic acid rich diet (13.3 J%) an augmented hypotensive dihydralazine effect (11-24 mm Hg) could be observed in acute experiments in conscious (1 mg/kg i.v.) and pentobarbital-anaesthetised (4 mg/kg i.v.) normotensive rats with different duration of the feeding period as well as in conscious (1 mg/kg i.v.) spontaneously hypertensive rats relative to linoleic acid poor (0.5 J%) fed animals. This effect was abolished by pretreatment with the cyclooxygenase inhibitors indomethacin (10 mg/kg i.v.) or acetylsalicylic acid (100 mg/kg i.v.). The chronotropic dihydralazine response was with one exception not different between the two dietary groups. In chronic experiments with spontaneously hypertensive rats the augmentation of the hypotensive dihydralazine effect (1 mg/kg X d, s.c.) after linoleic acid rich diet did not attain statistical significance after a 6-weak prefeeding period. The renovasodilatory action of dihydralazine (3 mg) was increased in isolated kidney preparations of linoleic acid rich fed rats. This effect was accompanied by a shift of the prostaglandin formation toward vasodepressive PGE. We conclude that the altered cardiovascular effects of dihydralazine after linoleic acid rich diet are primarily caused by changes in the formation of prostaglandins and the activity of the sympathetic nervous system.

Animals↗
PubMed1985

Effect of HDL and LDL from pre and post menopausal women on prostacyclin synthesis.

Earlier we found LDL and HDL to differentially affect the synthesis of PGI2 from PGH2 by pig aorta microsomes and that this depended on the gender of the lipoprotein donors. Here we report there are also differences in the effects of LDL and HDL from pre- and postmenopausal women. The influence of the lipoproteins from postmenopausal women on the PGI2 formation is similar to the action of lipoproteins from men. We suggest that endogenous PGI2 formation is regulated by the sex related composition of the lipoproteins.

6-Ketoprostaglandin F1 alpha↗
PubMed1985

Low density lipoproteins of male donors decrease prostacyclin (PGI2) and enhance thromboxane (TXA2) release from rat aortas perfused under pulsatile pressure.

The influence of low density lipoproteins (LDL)-cholesterol (1.69 +/- 0.08 mg/ml) and of high density lipoproteins (HDL)-cholesterol (0.62 +/- 0.09 mg/ml), respectively, on the levels of 6-oxo-PGF1 alpha and TXB2 in the perfusates of rat aortas perfused under pulsatile pressure was studied. After passage through the aortas the concentration of LDL-cholesterol was significantly decreased in the perfusates, whereas the HDL-cholesterol level was unchanged. In comparison to controls, perfused with lipoprotein free solution, the concentration of 6-oxo-PGF1 alpha was significantly decreased more than 50% by LDL and the TXB2 level was enhanced significantly by approximately 50%. This results in a significant rise of the TXB2/6-oxo-PGF1 alpha ratio in the perfusates. HDL did not significantly change the ratio of these eicosanoids in the perfusates. These results suggest that this concentration of LDL enhanced the formation of the proaggregatory TXA2 and decreased the formation of the antiaggregatory PGI2 in rat aortas perfused under pulsatile pressure. The proaggregatory action of an elevated level of LDL during the development of atherosclerosis in men may be also mediated by changes in the metabolism of eicosanoids of the vessel wall.

Animals↗
PubMed1985

Antihypertensive action of dietary polyunsaturated fatty acids in spontaneously hypertensive rats.

The experiments were carried out in order to clarify the mechanisms of attenuation of hypertension development by means of diets enriched with polyunsaturated fatty acids (PUFA) in spontaneously hypertensive rats (SHR). Female SHR were fed a linoleic acid rich (LAr) diet (13.3 cal % LA, sunflower oil), a linolenic acid rich (LNAr) diet (18.8 cal % LNA, 3.9 cal % LA; linseed oil) and a PUFA deficient diet (0.5 cal % LA, hydrogenated palm kernel fat), respectively, during the last week of pregnancy and during the suckling period. Corresponding diets were given to the male offspring up to an age of 16 weeks. Our results demonstrate that the attenuation of hypertension development in LAr and LNAr fed male SHR was paralleled by an increased in-vitro uptake of 14C-norepinephrine into cardiac and aortic tissues as well as an increased degradation rate of 14C-norepinephrine in cardiac tissue. Ex vivo prostaglandin (PG) formation was reduced after LNAr diet in the aorta (PGF2 alpha, PGI2-like material) and in the kidney medulla (PGE, PGF2 alpha). It is concluded that an increased catecholamine inactivation may play a role in the attenuation of hypertension development in LAr and LNAr diet fed SHR.

Animals↗
PubMed1984

Influence of indometacin and acetylsalicylic acid on the therapeutic effectiveness of talinolol in patients with essential hypertension.

Clinical-pharmacological investigations on interactions between cyclo-oxygenase inhibitors and beta-adrenoceptor blocking agents continuing, indometacin and acetylsalicylic acid (ASA) were added to a monotherapy of talinolol in two groups of hypertensive outpatients. Both added drugs reduced slightly the blood pressure lowering effect of talinolol, but did not alter its negative chronotropic effect. Indometacin abolished a talinolol-induced increase in serum triglycerides and caused a small decrease in serum cholesterol. ASA diminished slightly blood glucose. Probably the observed interactions and side effects are not important practically.

Adrenergic beta-Antagonists↗
PubMed1984

[Results of linseed oil and olive oil therapy in hyperlipoproteinemia patients].

Only few informations exist on the effect of different oils and the transformation of these precursor fatty acids to prostaglandins in patients with hyperlipoproteinemia. Therefore we investigated the impact of linseed oil and olive oil intake resp. on serum lipoprotein levels, platelet aggregation and fatty acid pattern of serum phospholipids and triglycerides resp. in patients with primary hypercholesterolemia (HC) (n = 13) and hypertriglyceridemia (HTG) (n = 16). The probands were randomly admitted to a 4 week test period with 30 ml olive or linseed oil intake. After linseed or olive oil intake all lipid fractions did not change significantly. Olive oil significantly reduced the platelet aggregation only in patients with HTG, whereas linseed oil failed to influence aggregation. After linseed oil intake there was a significant increase in linolenic and also in eicosapentaenoic acid content of phospholipids in patients with HTG. In contrast to HTG in HC linseed oil only increased significantly the linolenic acid fraction. Our data suggest, that the response of serum lipoproteins, fatty acids and platelet aggregation on modifications in dietary fats depends on the type of lipoprotein disorder.

Adult↗