Pravastatin modulates liver bile acid and cholesterol homeostasis in rats with chronic cholestasis.

BACKGROUND AND AIM: The administration of pravastatin to patients with cholestatic liver disease has suggested the potential of the drug with regard to reducing raised plasma cholesterol and bile acid levels. Information about the mechanisms associated with this effect is lacking. Thus, the aim of the present study is to evaluate pravastatin effects on the liver bile acid and cholesterol homeostasis in healthy and cholestatic rats. METHODS: Control sham-operated and reversibly bile duct-obstructed (BDO) rats were treated with pravastatin (1 or 5 mg/kg) or the vehicle alone for 7 days after surgery. RESULTS: Lower doses of pravastatin reduced bile acid plasma concentrations in cholestatic animals. The effect was associated with reduced liver mRNA expression of Cyp7a1, Cyp8b1, Mrp2, Ugt1a1 and the increased expression of Bsep. In addition, BDO-induced increase in the liver content of cholesterol was normalized by pravastatin. The change was accompanied by the reduced liver expression of Hmg-CoA reductase, LDL receptor, and Acat2, and induced the expression of Abca1 and Mdr2. These changes corresponded with the upregulation of nuclear receptors LXRα and PPARα, and the downregulation of FXR, CAR, SREBP-2 and HNF1α. High doses of pravastatin lacked any positive effects on bile acids and cholesterol homeostasis, and blocked bile formation through the reduction of the biliary excretion of bile acids. CONCLUSIONS: Pravastatin rendered a positive reduction in BDO-induced increases in plasma bile acid concentrations and cholesterol liver content, mainly through the transcriptionally-mediated downregulation of genes involved in the synthesis of these compounds in the liver.

A positive fluid balance does not deteriorate tissue metabolism during fluid resuscitation of sepsis.

OBJECTIVE: Hypovolemia has occurs frequently in sepsis. Due to pathologically increased permeability of the capillaries, the fluid leaks to the interstitium. An adequate fluid therapy is the corner stone to achieve circulatory stabilization and sufficient tissue perfusion; on the other hand, according to the data from the literature a tissue swelling is associated with a risk of deteriorated function of the tissues. The study aimed to examine the effect of a positive fluid balance on muscular metabolism. METHODS: The experimental study employed the model of sepsis in the domestical pig. Ten animals were randomly distributed into a control and a septic group. Sepsis was induced by intravenous administration of E. coli, followed by fluid resuscitation by crystaloids. Microdialysis samples were withdrawn at one-hour intervals for a period of 24 hours and values of lactate, pyruvate, glycerol, and glucose. RESULTS: Pearson's method revealed positive correlations between the lactate/pyruvate ratio and cumulative fluid balance in the septic group (R=0.292, p<0.001) and negative correlations in the control group (R=-0.279, p<0.05). In both groups, however, there was a gradual significant decrease in glycerol values. CONCLUSION: Fluid resuscitation results in positive fluid balance in both septic and control animals. This leads to circulatory stabilization of septic animals, but not a decrease in the anaerobic share of glycolysis. A positive fluid balance in control animals does not result in alteration of muscular aerobic glycolysis. Decreasing glycerol levels in both groups give evidence that a positive fluid balance does not exert a negative impact on cell metabolism.

Long term effects of soluble endoglin and mild hypercholesterolemia in mice hearts.

Soluble endoglin (sEng) released into the circulation was suggested to be related to cardiovascular based pathologies. It was demonstrated that a combination of high sEng levels and long-term exposure (six months) to high fat diet (HFD) resulted in aggravation of endothelial dysfunction in the aorta. Thus, in this study, we hypothesized that a similar experimental design would affect the heart morphology, TGFß signaling, inflammation, fibrosis, oxidative stress and eNOS signaling in myocardium in transgenic mice overexpressing human sEng. Three-month-old female transgenic mice overexpressing human sEng in plasma (Sol-Eng+ high) and their age-matched littermates with low levels of human sEng (Sol-Eng+ low) were fed a high-fat diet containing 1.25% of cholesterol and 40% of fat for six months. A blood analysis was performed, and the heart samples were analyzed by qRT-PCR and Western blot. The results of this study showed no effects of sEng and HFD on myocardial morphology/hypertrophy/fibrosis. However, the expression of pSmad2/3 and p-eNOS was reduced in Sol-Eng+ high mice. On the other hand, sEng and HFD did not significantly affect the expression of selected members of TGFß signaling (membrane endoglin, TGFßRII, ALK-5, ALK-1, Id-1, PAI-1), inflammation (VCAM-1, ICAM-1), oxidative stress (NQO1, HO-1) and heart remodeling (PDGFß, COL1A1, ß-MHC). In conclusion, the results of this study confirmed that sEng, even combined with a high-fat diet inducing hypercholesterolemia administered for six months, does not affect the structure of the heart with respect to hypertrophy, fibrosis, inflammation and oxidative stress. Interestingly, pSmad2/3/p-eNOS signaling was reduced in both the heart in this study and the aorta in the previous study, suggesting a possible alteration of NO metabolism caused by six months exposure to high sEng levels and HFD. Thus, we might conclude that sEng combined with a high-fat diet might be related to the alteration of NO production due to altered pSmad2/3/p-eNOS signaling in the heart and aorta.

Soluble endoglin and hypercholesterolemia aggravate endothelial and vessel wall dysfunction in mouse aorta.

BACKGROUND AND AIMS: Increased plasma levels of soluble endoglin (sEng) were detected in patients with endothelial dysfunction-related disorders and hypercholesterolemia. In this study, we hypothesized that high levels of sEng accompanied by mild hypercholesterolemia could aggravate endothelial and vessel wall dysfunction and affect endoglin/eNOS signaling in mouse aorta. METHODS: Three-month-old female transgenic mice on CBAxC57BL/6J background, with high levels of sEng (Sol-Eng+high HFD), and their littermates with low levels of sEng (Sol-Eng+low HFD), were fed a high fat diet for six months. Plasma samples were used for biochemical, ELISA and Luminex analyses of total cholesterol, sEng and inflammatory markers. Functional parameters of aorta were assessed with wire myograph 620M. Western blot analyses of membrane endoglin/eNOS signaling and endothelial dysfunction/inflammation markers in aorta were performed. RESULTS: Functional analysis of aorta showed impaired KCl induced vasoconstriction, endothelial-dependent relaxation after the administration of acetylcholine as well as endothelial-independent relaxation induced by sodium nitroprusside in the Sol-Eng+high HFD group compared to the Sol-Eng+low HFD group. Ach-induced vasodilation after administration of l-NAME was significantly higher in the Sol-Eng+high HFD group compared to the Sol-Eng+low HFD group. The expression of endoglin, p-eNOS/eNOS, pSmad2/3/Smad2/3 signaling pathway was significantly lower in the Sol-Eng+high HFD group compared to the Sol-Eng+low HFD group. CONCLUSIONS: The results indicate that long-term hypercholesterolemia combined with high levels of sEng leads to the aggravation of endothelial and vessel wall dysfunction in aorta, with possible alterations of the membrane endoglin/eNOS signaling, suggesting that high levels of soluble endoglin might be considered as a risk factor of cardiovascular diseases.

Application of the comet assay method in clinical studies.

The comet assay or single-cell gel electrophoresis (SCGE) assay is now widely accepted as a standard method for assessing DNA damage in individual cells. It finds use in a broad variety of applications including human biomonitoring, genotoxicology, ecological monitoring and as a tool for investigation of DNA damage and repair in different cell types in response to a range of DNA-damaging agents. The comet assay should be eminently suitable for use in clinical practice since it is a relatively simple and inexpensive technique which requires only a few cells, and results can be obtained within a matter of hours. This method can be used in the study of cancer as well as in lifestyle and dietary studies. In cancer it is useful for measuring DNA damage before, throughout and after therapy (either radiotherapy or chemotherapy). Another use of this method is in lifestyle study, such as investigation of the effect on DNA of common human activities (e.g. smoking, or working with a potentially genotoxic agent). The final use of comet assay in this paper is dietary study. In this type of study we observe the effects of consumption of specific foods or supplements which may be protective for DNA against damage.

Hypocholesterolemia in clinically serious conditions--review.

BACKGROUND: Cholesterol is an essential component of cell membranes, precursor of steroids, biliary acids and other components of serious importance in live organism. Cholesterol synthesis is a complicated and energy-demanding process. Real daily need of cholesterol and mechanisms of decline cholesterol levels in critical ill are unknown. During stressful situations a significant hypocholesterolaemia may be found. Hypocholesterolemia has been known for a number of years to be a significant prognostic indicator of increased morbidity and mortality connected with a whole spectrum of pathological conditions. The aim of article is the elucidation of the role and importance of hypocholesterolaemia during the intensive care. METHODS AND RESULTS: We examined studies that are engaged in problems of hypocholesterolemia in critically ill. Very low levels of total as well as LDL cholesterol are most frequently found in serious polytrauma, after extensive surgery, in serious infections, in protracted hypovolemic shock. It is still not clear whether hypocholesterolemia reflects only a serious metabolic disorder, which results from a life-threatening condition, or whether it has an active role in evolution and outcome. CONCLUSIONS: Hypocholesterolemia is commonly observed in critically ill patients. Nevertheless, it is not known whether it is a secondary manifestation of disease, or whether it actively contributes to deterioration of the disease. Although the contribution of hypocholesterolemia to mortality is modest compared with known risk factors such as increased severity of illness and the development of nosocomial infection, low serum lipid concentrations represent a potential therapeutic target in sepsis.

Effect of atorvastatin on non-cholesterol sterols in patients with type 2 diabetes mellitus and cardiovascular disease.

An increased risk of cardiovascular morbidity and mortality in diabetes mellitus type 2 has been associated with disturbances of lipid homeostasis. Recently, decreased intestinal absorption of cholesterol and increased liver cholesterol production have been reported. To investigate the influence of cholesterol lowering therapy using statin on cholesterol turnover in diabetes mellitus type 2, the levels of non-cholesterol based sterols were studied. One hundred and thirty five patients with type 2 diabetes and non-diabetic controls with cardiovascular diseases were studied. Both groups were divided into two subgroups: treated with atorvastatin and without statin therapy. The diabetics showed significantly higher levels of lathosterol (6.97micromol l(-1) versus 5.11micromol l(-1), p = 0.012) and lower levels of sitosterol (5.03micromol l(-1) versus 8.98micromol l(-1), p < 0.001) and campesterol (6.35micromol l(-1) versus 9.80micromol l(-1), p < 0.001). Non-diabetics showed no significant differences in non-cholesterol based sterols in relation to atorvastatin therapy. A significantly lower level of lathosterol as well as a decrease in lathosterol/cholesterol ratio in the statin treated groups was found in diabetics (4.11micromol l(-1) versus 7.83micromol l(-1), p < 0.001). The results based on ANOVA analysis show that the effect of atorvastatin on the lathosterol level is more pronounced in diabetics. Regression analysis showed the relationship between increased triglycerides levels and the increase in cholesterol synthesis. The calculated regression model for loglathosterol in diabetics has the following form: log(lathosterol) = 2.76 - 0.52.statin + 0.22.cholesterol (ANOVA, p < 0.001, R(2) = 34%, p = 0.005 for statin, p < 0.001 for cholesterol). We conclude that in spite the total cholesterol level in diabetics type 2 is not increased, its endogenous synthesis is enhanced. Our results show that the diabetics type 2 with increased serum lathosterol and expressed metabolic syndrome (mild increase of triglycerides) might represent a suitable group for intensive treatment with statins.

Fluorometric assay of lipoperoxides and chromatographic analysis of alpha-tocopherol and fatty acids as biomarkers of risk from coronary atherosclerosis.

There has been growing interest in the quantitative determination of biochemical predictors of atherogenesis. The aim of the present study was to investigate association of lipoperoxidation biomarkers known to be pro-atherogenic (thiobarbituric acid reactive substance activity, TBARS) or anti-atherogenic (alpha-tocopherol) with the fatty acid status, and relate it to the coronary artery disease (CAD) as assessed by coronary angiography in patients with stable angina pectoris. We found that serum lipoproteins and TBARS did not differ significantly. However there was significant correlation of TBARS with total vitamin E (P=0.02) and vitamin E in very low-density lipoprotein (VLDL) (P=0.02) and low-density lipoprotein (LDL) (P=0.01), with LDL-linoleic acid (P=0.01), and high-density lipoprotein-linoleic acid (P=0.02). There was significant correlation of total vitamin E (P=0.01) and VLDL-vitamin E (P=0.01) with the degree of CAD. We conclude that TBARS and alpha-tocopherol could not be evaluated as biomarkers for the severity of CAD among the patients with stable angina pectoris.