Baroreflex sensitivity and oxidative stress in the LDL receptor knockout mice

This study alms at observing the effect of low-density lipoprotein (LDL) receptor deficiency in cholesterol blood levels, baroreflex sensitivity (BRS), nitric oxide (NO) bioavailability, and oxidative stress. The lack of LDL receptors in mice significantly increased the cholesterol blood levels (179 +/- 35 vs. 109 +/- 13 mg/dL) in the knockout (KO) mice compared to control. There was no difference in basal mean arterial pressure and heart rate between the groups. However, in KO mice the BRS was significantly attenuated and the antioxidant enzyme activities, measured in erythrocytes and heart, were significantly decreased. On the other hand, the oxidative damage measured by chemiluminescence and carbonyls was increased, while total plasma nitrate levels were lower in KO mice, indicating a decrease in NO availability. In conclusion, these results indicate that the lack of LDL receptor increased cholesterol blood levels, induced oxidative stress and decreased BRS. (C) 2008 Elsevier GmbH. All rights reserved.

Reversal of Postprandial Endothelial Dysfunction by Cyclooxygenase Inhibition in Healthy Volunteers

The aim of this study was to evaluate the role of cyclooxygenase (COX) in venous vascular reactivity changes after an oral lipid overload (OLO). Venous endothelial function (dorsal hand vein technique) was evaluated in fasting, 30 minutes after COX inhibition (aspirin-fasting), 2 to 4 hours after an OLO (1000 kcal, 58% fat), and again after COX inhibition (aspirin-OLO, 600 mg/200 mL water) in 10 healthy adults (age, 28.1 +/- 1.3 years; body mass index, 22.3 +/- 0.6 kg/m(2)). Fasting, 2- to 4-hour post-OLO, and 60-minute postaspirin plasma glucose, insulin, and lipids were also evaluated. The OLO increased triglycerides and insulin, reduced low-density lipoprotein and high-density lipoprotein, but glycemia and total cholesterol remained unchanged. There were no metabolic differences between OLO and aspirin-OLO. In fasting, aspirin reduced acetylcholine-induced venodilation (107.0% +/- 14% versus 57.3% +/- 11%; P < 0.001). Vascular reactivity was blunted after the OLO (phenylephrine dose: 0.3 +/- 0.2 fasting versus 1.9 +/- 0.8 nmol/min after OLO; P < 0.001) and was partially corrected by aspirin (0.4 +/- 0.2; P < 0.001). Similar changes were observed in maximum venodilation after acetylcholine (107.0% +/- 14% fasting versus 60.4% +/- 9% after OLO, P < 0.001; aspirin-OLO: 95.9% +/- 6%; P < 0.001). The responses to sodium nitroprusside remained unchanged during the study. We conclude that the OLO reduction in the endothelium-dependent venoconstruction and venodilation is partially the result of the action of COX.

Hepatic denervation impairs the assembly and secretion of VLDL-TAG

VLDL secretion is a regulated process that depends on the availability of lipids, apoB and MTP. Our aim was to investigate the effect of liver denervation upon the secretion of VLDL and the expression of proteins involved in this process. Denervation was achieved by applying a 85% phenol solution onto the portal tract, while control animals were treated with 9% NaCl. VLDL secretion was evaluated by the Tyloxapol method. The hepatic concentration of TAG and cholesterol, and the plasma concentration of TAG, cholesterol, VLDL-TAG, VLDL-cholesterol and HDL-cholesterol were measured, as well as mRNA expression of proteins involved in the process of VLDL assembly. Hepatic acinar distribution of MTP and apoB was evaluated by immunohistochemistry. Denervation increased plasma concentration of cholesterol (125.3 +/- 10.1 vs. 67.1 +/- 4.9 mg dL(-1)) and VLDL-cholesterol (61.6 +/- 5.6 vs. 29.4 +/- 3.3 mg dL(-1)), but HDL-cholesterol was unchanged (45.5 +/- 6.1 vs. 36.9 +/- 3.9 mg dL(-1)). Secretion of VLDL-TAG (47.5 +/- 23.8 vs. 148.5 +/- 27.4 mg dL h(-1)) and mRNA expression of CPT I and apoB were reduced (p < 0.01) in the denervated animals. MTP and apoB acinar distribution was not altered in the denervated animals, but the intensity of the reaction was reduced in relation to controls. Copyright (C) 2008 John Wiley & Sons, Ltd.

Post-menopausal hormone therapy reduces autoantibodies to oxidized apolipoprotein B100

The aim of the study was to verify whether post-menopausal hormone replacement therapy (HRT) modifies autoantibody titers against oxidized low-density lipoprotein (LDL) (anti-LDLoxi), against epitopes of oxidized apolipoprotein B100 and common carotid intima-media thickness (IMT) in these women. Sixty-eight women in pre-menopause (PMW) and 216 in post-menopause (POMW) were recruited; eighty-three had undergone HRT for at least 12 months, where 48 received conjugated estrogens alone (EHRT) and 35 received conjugated estrogen and medroxyprogesterone acetate (CHRT). ELISA was used to determine autoantibodies. Lipoprotein lipase (LPL), hepatic lipase (HL), cholesterol ester transfer protein (CETP) and phospholipid transfer protein (PLTP) activities were assayed by radiometric methods. IMT was measured using Doppler ultrasound. Anti-oxidized LDL and anti-D antibodies increased by 40% (p <= 0.003) and 42% (p <= 0.006), respectively, with menopause. There was a surprising and significant 7% reduction in anti-D2 antibody titers with HRT (p <= 0.050), indicating a positive effect of treatment on the immune response to oxidized LDL. Combined HRT decreased activities of HL and LPL. HRT did not change common carotid IMT, which was increased by 32% as expected after menopause (p <= 0.030). This study describes, for the first time, the protective effect of HRT on decreasing autoantibody titers against oxidized apolipoprotein B in LDL.

Role of PPAR-gamma in the Modulation of CD36 and FcgammaRII induced by LDL with Low and High Degrees of Oxidation During the Differentiation of the Monocytic THP-1 Cell Line

Scavenger or Fc gamma receptors are important for capture and clearance of modified LDL particles by monocytes/macrophages. Uptake via scavenger receptors is not regulated by intracellular levels of cholesterol and in consequence, macrophages develop into foam cells in the arterial intima. The levels of scavenger receptor CD36 are increased in atherosclerotic lesions and there is evidence that some components of oxLDL auto-regulate the expression of this receptor. Fc gamma receptor expression is increased in cardiovascular diseases but it is not known weather their expression is regulated by oxLDL. The biological properties of oxLDLs vary depending on the degree of oxidation. In the present study we investigated the effect of LDL particles showing extensive or low oxidation (HoxLDL and LoxLDL) on the expression of CD36 and Fc gamma RII in a human monocytic cell line (THP-1), differentiated or not to macrophage, and the involvement of PPAR gamma. It was found that both forms of oxLDL are able to increase the expression of CD36 and Fc gamma RII and that this effect is dependent on the degree of oxidation and of the stage of cell differentiation ( monocyte or macrophage). We also showed that the increased expression of Fc gamma RII is dependent on PPAR. whereas that of the CD36 is independent of PPAR gamma. Copyright (c) 2008 S. Karger AG, Basel

Pivotal Role for Platelet-Activating Factor Receptor in CD36 Expression and oxLDL Uptake by Human Monocytes/Macrophages

The uptake of oxLDL by CD36 is not regulated by intracellular levels of cholesterol, leading to macrophage differentiation into foam cells which play a major role in atherosclerosis. Furthermore, oxLDL competes with PAF in macrophages for binding to PAF receptors (PAFR). Here we investigated the involvement of PAFR in CD36 expression and uptake of oxLDL by human monocytes/macrophages. Adherent peripheral blood mononuclear cells were treated with PAFR-antagonists (WEB2170, CV3988); inhibitors of ERK1/2 (PD98059), p38 (SB203580), JNK (SP600125) or diluents, before stimulation with oxLDL or PAF. After 24 h, uptake of FITC oxLDL and expression of CD36 was determined by flow cytometry and phosphorylation of MAP-kinases by Western blot. It was shown that the uptake of oxLDL was reduced by PAFR antagonists. CD36 expression was up-regulated by oxLDL, an effect reversed by PAFR antagonists. The up-regulation of CD36 and oxLDL uptake both required MAP-kinases activation. The oxLDL induced ERK1/2 and JNK but not p38 phosphorylation was reversed by PAFR-antagonists suggesting that oxLDL signalling involves PAFR dependent and independent pathways. In macrophages from PAFR(-/-) mice, oxLDL was unable to up-regulate CD36 expression and the oxLDL uptake was reduced compared to wild type. These results suggest that oxLDL interacts with PAFR in macrophages to increase CD36 expression and oxLDL uptake. Whereas pharmacological intervention at the level of PAFR would be beneficial in atherosclerosis remains to be determined. Copyright (C) 2011 S. Karger AG, Basel

Lack of effects of isoflavones on the lipid profile of Brazilian postmenopausal women

Objective: To evaluate the effects of soy isoflavone supplementation on profile lipid and endogenous hormone levels. Methods: In this double-blind, placebo-controlled Study, 47 post menopausal women 47-66 v of age received 40 mg of isoflavone (n = 25) or 40 mg of casein placebo (11 = 22). Cardiovascular risk factors were assessed by evaluating lipid profile at baseline and after 6 mo of treatment. To examine the effects of this regime on endogenous hormone levels, follicle-stimulating hormone and beta-estradiol were measured. Urinary isoflavone concentrations (genistein and daidzein) were measured as markers of both compliance and absorption using high performance liquid chromatography. Baseline characteristics were compared by the unpaired Student`s t-test. Within-group changes were determined by paired Student`s t-test and comparison between the isoflavone and casein placebo groups were determined by analysis of variance. Results: Lipid levels (low-density lipoprotein and total cholesterol) similarly decreased in both,groups. High-density lipoprotein increased significantly in both groups and cannot thus be attributable to treatment: the reason for Such variation is unknown and can be attributed to chance or to bias (even that of a real placebo effect in both groups or perhaps in spontaneous changes in exercise and dietary habits of patients after their inclusion). Furthermore, in both groups very low-density lipoprotein and triacylglycerol levels increased in a non-significant manner. Conclusion: The results of the present Study do not support any biologically significant estrogenic effects of isoflavone on the parameters assessed. Further research will he necessary to definitively assess the safety and efficacy of isoflavone. (C) 2008 Elsevier Inc. All rights reserved.

Enhancement on the Europium emission band of Europium chlortetracycline complex in the presence of LDL

Low-density lipoprotein (LDL) particles are the major cholesterol-carrying lipoprotein in the human circulation from the liver to peripheral tissues. High levels of LDL-Cholesterol (LDL-C) are known risk factor for the development of coronary artery disease (CAD). The most common approach to determine the LDLC in the clinical laboratory involves the Friedewald formula. However, in certain situations, this approach is inadequate. In this paper we report on the enhancement on the Europium emission band of Europium chlortetracycline complex (CTEu) in the presence of LDL. The emission intensity at 615 nm of the CTEu increases with increasing amounts of LDL. This phenomenon allowed us to propose a method to determine the LDL concentration in a sample composed by an aqueous solution of LDL. With this result we obtained LDL calibration curve, LOD (limit of detection) of 0.49 mg/mL and SD (standard deviation) of 0.003. We observed that CTEu complex provides a wider dynamic concentration-range for LDL determination than that from Eu-tetracycline previously. The averaged emission lifetimes of the CTEu and CTEu with LDL (1.5 mg/mL) complexes were measured as 15 and 46 Its, respectively. Study with some metallic interferents is presented. (C) 2010 Elsevier Inc. All rights reserved.

Early Increase in Autoantibodies Against Human Oxidized Low-Density Lipoprotein in Hypertensive Patients After Blood Pressure Control

BACKGROUND Oxidized lipoproteins and antioxidized low-density lipoprotein (anti-oxLDL) antibodies (Abs) have been detected in plasma in response to blood pressure (BP) elevation, suggesting the participation of the adaptive immune system. Therefore, treatment of hypertension may act on the immune response by decreasing oxidation stimuli. However, this issue has not been addressed. Thus, we have here analyzed anti-oxLDL Abs in untreated (naive) hypertensive patients shortly after initiation of anti hypertensive therapeutic regimens. METHODS Titers of anti-oxLDL Abs were measured in subjects with recently diagnosed hypertension on stage 1 (n = 94), in primary prevention of coronary disease, with no other risk factors, and naive of anti hypertensive medication at entry. Subjects were randomly assigned to receive perindopril, hydrochlorothiazide (HCTZ), or indapamide (INDA) for 12 weeks, with additional perindopril if necessary to achieve BP control. Abs against copper-oxidized LDL were measured by enzyme-linked immunosorbent assay. RESULTS Twelve-week antihypertensive treatment reduced both office-based and 24-h ambulatory BP measurements (P < 0.0005). The decrease in BP was accompanied by reduction in thiobarbituric acid-reactive substances (TBARS) (P < 0.05), increase in anti-oxLDL Ab titers (P < 0.005), and improvement in flow-mediated dilation (FMD) (P < 0.0005), independently of treatment. Although BP was reduced, we observed favorable changes in anti-oxLDL titers and FMD. CONCLUSIONS We observed that anti-oxLDL Ab titers increase after antihypertensive therapy in primary prevention when achieving BP targets. Our results are in agreement with the concept that propensity to oxidation is increased by essential hypertension and anti-oxLDL Abs may be protective and potential biomarkers for the follow-up of hypertension treatment.

Investigation of the Europium Emission Spectra of the Europium-Oxytetracycline Complex in the Presence of Human Low-Density Lipoproteins

Low-Density Lipoprotein (LDL), often known as ""bad cholesterol"" is one of the responsible to increase the risk of coronary arterial diseases. For this reason, the cholesterol present in the LDL particle has become one of the main parameters to be quantified in routine clinical diagnosis. A number of tools are available to assess LDL particles and estimate the cholesterol concentration in the blood. The most common methods to quantify the LDL in the plasma are the density gradient ultracentrifugation and nuclear magnetic resonance (NMR). However, these techniques require special equipments and can take a long time to provide the results. In this paper, we report on the increase of the Europium emission in Europium-oxytetracycline complex aqueous solutions in the presence of LDL. This increase is proportional to the LDL concentration in the solution. This phenomenum can be used to develop a method to quantify the number of LDL particles in a sample. A comparison between the performances of the oxytetracycline and the tetracycline in the complexes is also made.

Laurdan Spectrum Decomposition as a Tool for the Analysis of Surface Bilayer Structure and Polarity: a Study with DMPG, Peptides and Cholesterol

The highly hydrophobic fluorophore Laurdan (6-dodecanoyl-2-(dimethylaminonaphthalene)) has been widely used as a fluorescent probe to monitor lipid membranes. Actually, it monitors the structure and polarity of the bilayer surface, where its fluorescent moiety is supposed to reside. The present paper discusses the high sensitivity of Laurdan fluorescence through the decomposition of its emission spectrum into two Gaussian bands, which correspond to emissions from two different excited states, one more solvent relaxed than the other. It will be shown that the analysis of the area fraction of each band is more sensitive to bilayer structural changes than the largely used parameter called Generalized Polarization, possibly because the latter does not completely separate the fluorescence emission from the two different excited states of Laurdan. Moreover, it will be shown that this decomposition should be done with the spectrum as a function of energy, and not wavelength. Due to the presence of the two emission bands in Laurdan spectrum, fluorescence anisotropy should be measured around 480 nm, to be able to monitor the fluorescence emission from one excited state only, the solvent relaxed state. Laurdan will be used to monitor the complex structure of the anionic phospholipid DMPG (dimyristoyl phosphatidylglycerol) at different ionic strengths, and the alterations caused on gel and fluid membranes due to the interaction of cationic peptides and cholesterol. Analyzing both the emission spectrum decomposition and anisotropy it was possible to distinguish between effects on the packing and on the hydration of the lipid membrane surface. It could be clearly detected that a more potent analog of the melanotropic hormone alpha-MSH (Ac-Ser(1)-Tyr(2)-Ser(3)-Met(4)-Glu(5)-His(6)-Phe(7)-Arg(8)-Trp(9)-Gly(10)-Lys(11)-Pro(12)-Val(13)-NH(2)) was more effective in rigidifying the bilayer surface of fluid membranes than the hormone, though the hormone significantly decreases the bilayer surface hydration.

Cholesterol Mediates Chitosan Activity on Phospholipid Monolayers and Langmuir-Blodgett Films

The polysaccharide chitosan has been largely used in many biological applications as a fat and cholesterol reducer, bactericide agent, and wound healing material. While the efficacy for some of such uses is proven, little is known about the molecular-level interactions involved in these applications. In this study, we employ mixed Langmuir and Langmuir-Blodgett (LB) films of negatively charged dimyristoyl phosphatidic acid (DMPA) anti cholesterol as cell membrane models to investigate the role of cholesterol in the molecular-level action of chitosan. Chitosan does not remove cholesterol froth the monolayer. The interaction with chitosan tends to expand the DMPA monolayer due to its interpenetration within the film. On the other hand, cholesterol induces condensation of the DMPA monolayer. The competing effects cause the surface pressure isotherms of mixed DMPA-cholesterol films on a chitosan subphase to be unaffected by the cholesterol mole fraction, due to distinct degrees of chitosan penetration into the film in the presence of cholesterol. By combining polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS) and sum-frequency generation spectroscopy (SFG), we showed that chitosan induces order into negatively charged phospholipid layers, whereas the opposite occurs for cholesterol. In conclusion, chitosan has its penetration in the film modulated by cholesterol, and electrostatic interactions with negatively charged phospholipids, such as DMPA, are crucial for the action of chitosan.

A logic-based agent that plans for extended reachability goals

Planning to reach a goal is an essential capability for rational agents. In general, a goal specifies a condition to be achieved at the end of the plan execution. In this article, we introduce nondeterministic planning for extended reachability goals (i.e., goals that also specify a condition to be preserved during the plan execution). We show that, when this kind of goal is considered, the temporal logic CTL turns out to be inadequate to formalize plan synthesis and plan validation algorithms. This is mainly due to the fact that the CTL`s semantics cannot discern among the various actions that produce state transitions. To overcome this limitation, we propose a new temporal logic called alpha-CTL. Then, based on this new logic, we implement a planner capable of synthesizing reliable plans for extended reachability goals, as a side effect of model checking.

Cardiovascular Disease Parameters in Periodontitis

Background: Recently, there has been an increasing in the impact of oral health on atherosclerosis and subsequent cardiovascular disease. The aim of this study is to investigate the association between chronic periodontitis and cardiovascular risk markers. Methods: Forty patients with periodontitis and 40 healthy gender-, body mass index-, and age-matched individuals were compared by measuring total cholesterol, high-density lipoprotein, low-density lipoprotein, triglycerides, levels of cytokines, antibodies against oxidized low-density lipoprotein, thiobarbituric acid reactive substances, total and differential white blood cell counts, and the non-linear index of refraction. Results: The levels of triglycerides and high-density lipoprotein in periodontitis patients were significantly higher and lower, respectively (P=0.002 and P=0.0126), compared to controls. Total cholesterol, low-density lipoprotein, and lipid peroxide levels were the same in both groups (P = 0.2943, P = 0.1284, and P = 0.067, respectively). Interleukin (IL)-6 and -8, antibodies against oxidized low-density lipoprotein, and leukocyte and neutrophil counts were significantly higher in periodontitis patients (P<0.05). The value of the non-linear index of refraction of low-density lipoprotein solutions was higher in the controls (P = 0.015) compared to individuals with periodontitis. Conclusion: Our results confirmed and further strengthened the suggested association between coronary artery disease and periodontitis. J Periodontol 2009;80:378-388.

Generation of Cholesterol Carboxyaldehyde by the Reaction of Singlet Molecular Oxygen [O(2) ((1)Delta(g))] as Well as Ozone with Cholesterol

A few years ago, it was reported that ozone is produced in human atherosclerotic arteries, on the basis of the identification of 3 beta-hydroxy-5-oxo-5,6-secocholestan-6-al and 3 beta-hydroxy-5 beta-hydroxy-B-norcholestane-6 beta-carboxaldehyde (ChAld) as their 2,4-dinitrophenylhydrazones. The formation of endogenous ozone was attributed to water oxidation catalyzed by antibodies, with the formation of dihydrogen trioxide as a key intermediate. We now report that ChAld is also generated by the reaction of cholesterol with singlet molecular oxygen [O(2) ((1)Delta(g))] that is produced by photodynamic action or by the thermodecomposition of 1,4-dimethylnaphthalene endoperoxide, a defined pure chemical source of O(2) ((1)Delta(g)). On the basis of (18)O-labeled ChAld mass spectrometry, NMR, light emission measurements, and derivatization studies, we propose that the mechanism of ChAld generation involves the formation of the well-known cholesterol 5 alpha-hydroperoxide (5 alpha-OOH) (the major product of O(2) ((1)Delta(g))-oxidation of cholesterol) and/or a 1,2-dioxetane intermediate formed by O(2) ((1)Delta(g)) attack at the Delta(5) position. The Hock cleavage of 5 alpha-OOH (the major pathway) or unstable cholesterol dioxetane decomposition (a minor pathway, traces) gives a 5,6-secosterol intermediate, which undergoes intramolecular aldolization to yield ChAld. These results show clearly and unequivocally that ChAld is generated upon the reaction of cholesterol with O(2) ((1)Delta(g)) and raises questions about the role of ozone in biological processes.