Atherosclerosis: Viewing the problem from a different perspective including possible treatment options

This paper proposes that atherosclerosis is initiated by a signaling event that deposits calcium hydroxyapatite (Ca-HAP). This event is preceded by a loss of mechanical structure in the arterial wall. After Ca-HAP has been deposited, it is unlikely that it will be reabsorbed because the solubility product constant (K sp) is very small, and the large stores of Ca +2 and PO 4-3 in the bones oppose any attempts to dissolve Ca-HAP by decreasing the common ions. The hydroxide ion (OH -) of Ca-HAP can be displaced in nature by fluoride (F -) and carbonate (CO 3-2) ions, and it is proposed that anions associated with cholesterol ester hydrolysis and, in very small quantities, the enolate of 7-ketocholesterol could also displace the OH -of Ca-HAP, forming an ionic bond. The free energy of hydration of Ca-HAP at 310 K is most likely negative, and the ionic radii of the anions associated with the hydrolysis of cholesterol ester are compatible with the substitution. Furthermore, examination of the pathology of atherosclerotic lesions by Raman and NMR spectroscopy and confocal microscopy supports deposition of Ca-HAP associated with cholesterol. Investigating the affinity of intermediates of cholesterol hydrolysis for Ca-HAP compared to lipoproteins such as HDL, LDL, and VLDL using isothermic titration calorimetry could add proof of this concept and may lead to the development of a new class of medications targeted at the deposition of cholesterol within Ca-HAP. Treatment of acute ischemic events as a consequence of atherosclerosis with denitrogenation and oxygenation is discussed. © the author(s), publisher and licensee Libertas Academica Ltd.

Recombinant Adeno-Associated Virus-Mediated Gene Therapy for Treatment of Familial Hypercholesterolemia in Rabbits

Familial hypercholesterolemia (FH) is a genetic disorder characterized by abnormally high concentrations of low-density lipoprotein-cholesterol (LDLcholesterol) in the blood that can contribute to heart disease. FH can result from a defect in the gene for the LDL receptor (LDL-R). FH patients lacking functional LDL-R may benefit from viral-mediated transfer of a functional copy of the open reading frame (ORF) of the LDL-R. Since a recombinant adeno-associated virus (rAAV) is not immunogenic and can be mass-produced, it shows promise for gene therapy applications. AAV6 and AAV8 have been shown to specifically transduce hepatocytes in several species, which normally remove the majority of LDL-cholesterol from the blood via LDL-R-mediated endocytosis. Because of the potential of rAAV to treat FH by delivery of a correct LDL-R ORF to hepatocytes, the liver specificity of these two AAV serotypes was evaluated. Additionally, rabbits were chosen as the animal model for this study because a specific strain of rabbits, Watanabe heritable hyperlipidemic (WHHL), adequately mimics the pathology of FH in humans. Exposure of rabbit liver to rAAV with the marker LacZ and subsequent inspection of liver tissue showed that AAV8 transduced rabbit liver more efficiently than AAV6. To assess the feasibility of producing a rAAV capable of transferring the LDL-R ORF to rabbit hepatocytes in vivo, rAAV8-LDL-R was mass-produced by a baculovirus system in suspension grown insect cells.

Serum cholesterol levels within the high normal range are associated with better cognitive performance among Chinese elderly

© 2016, Serdi and Springer-Verlag France.Objectives: The association between cognitive function and cholesterol levels is poorly understood and inconsistent results exist among the elderly. The purpose of this study is to investigate the association of cholesterol level with cognitive performance among Chinese elderly. Design: A cross-sectional study was implemented in 2012 and data were analyzed using generalized additive models, linear regression models and logistic regression models. Setting: Community-based setting in eight longevity areas in China. Subjects: A total of 2000 elderly aged 65 years and over (mean 85.8±12.0 years) participated in this study. Measurements: Total cholesterol (TC), triglycerides (TG), low density lipoprotein cholesterol (LDL-C) and high density lipoprotein cholesterol (HDL-C) concentration were determined and cognitive impairment was defined as Mini-Mental State Examination (MMSE) score≤23. Results: There was a significant positive linear association between TC, TG, LDL-C, HDL-C and MMSE score in linear regression models. Each 1 mmol/L increase in TC, TG, LDL-C and HDL-C corresponded to a decreased risk of cognitive impairment in logistic regression models. Compared with the lowest tertile, the highest tertile of TC, LDL-C and HDL-C had a lower risk of cognitive impairment. The adjusted odds ratios and 95% CI were 0.73(0.62–0.84) for TC, 0.81(0.70–0.94) for LDL-C and 0.81(0.70–0.94) for HDL-C. There was no gender difference in the protective effects of high TC and LDL-C levels on cognitive impairment. However, for high HDL-C levels the effect was only observed in women. High TC, LDL-C and HDL-C levels were associated with lower risk of cognitive impairment in the oldest old (aged 80 and older), but not in the younger elderly (aged 65 to 79 years). Conclusions: These findings suggest that cholesterol levels within the high normal range are associated with better cognitive performance in Chinese elderly, specifically in the oldest old. With further validation, low cholesterol may serve a clinical indicator of risk for cognitive impairment in the elderly.

Los diferentes tipos de láser y sus aplicaciones en podología

Los diferentes tipos de láseres, sobre todo el láser de diodo, irrumpen en la terapéutica podológica para proporcionar una alternativa más de tratamiento en muchas patologías que son el día a día de las consultas. El buen manejo y el conocimiento de sus características son requisitos imprescindibles para no tener efectos secundarios indeseados y poder llevar a cabo tratamientos poco dolorosos, minimizando el tiempo total, y muchas veces proporcionando una solución a diversas patologías.

COVALENT LIPOPROTEIN(A) ASSEMBLY: Characterization of Oxidase Activity Responsible for Catalyzing Covalent Lipoprotein(a) Assembly

Lipoprotein(a) (Lp(a)) has been identified as an emerging risk factor for the development of vascular diseases. The Lp(a) particle is assembled in a 2-step process upon secretion of the LDL and apo(a) components from hepatocytes. Work done by the Koschinsky group has identified an oxidase-like activity present in the conditioned medium (CM) harvested from human hepatoma (HepG2), as well as HEK 293 (human endothelian kidney) cells that catalyzes the rate of covalent Lp(a) formation. We have taken a candidate enzyme approach to identifying this oxidase activity. Specifically, we have proposed that the QSOX (Quiescin/sulfhydryl oxidase) is responsible for catalysis of covalent Lp(a) assembly. An oxidase activity assay developed by Dr. Thorpe (University of Delaware) was used to detect QSOX1 in CM harvested from cultured cell lines that catalyze covalent Lp(a) assembly. In addition, the QSOX1 transcript was identified in each cell line and quantified with the use of Real-Time RT-PCR. Quantitative assays of covalent Lp(a) assembly were performed to study some characteristics of the unkwown oxidase activity. First, conditioned medium was dialyzed through a 5 kDa cutoff, as this has previously been shown to reduce the aforementioned oxidase activity. Purified QSOX was then added back to the reaction and the rate of catalysis was observed. The addition of QSOX appeared to enhance the rate of covalent Lp(a) assembly in a dose-dependent manner. Additional covalent Lp(a) assembly assays were performed where various chemicals were added to determine whether Lp(a) assembly was affected. The addition of EDTA did not affect covalent assembly, suggesting that the oxidase activity may not be metallo-dependent. Moreover, dose-dependent addition of Calcium, DTT, Copper and glutathione to dialyzed medium also did not affect the rate of Lp(a) assembly. Taken together, these studies will aid in identifying the nature of the oxidase activity that catalyzes covalent Lp(a) assembly. This will provide us with valuable information on how Lp(a) particles are assembled, and may lead to the development of drugs inhibiting Lp(a) formation.

THE ROLE OF LIPOPROTEIN(a)/APOLIPOPROTEIN(a) IN ENDOTHELIAL DYSFUNCTION: MECHANISTIC STUDIES IN VASCULAR ENDOTHELIUM

Multiple lines of evidence suggest that elevated plasma lipoprotein(a) (Lp(a)) concentrations are a significant risk factor for the development of a number of vascular diseases including coronary heart disease and stroke. Lp(a) consists of a low-density lipoprotein (LDL)-like moiety and an unique glycoprotein, apolipoprotein(a) (apo(a)), that is covalently attached to the apolipoproteinB-100 (apoB-100) component of LDL by a single disulfide bond. Many studies have suggested a role for Lp(a) in the process of endothelial dysfunction. Indeed, Lp(a) has been shown to increase both the expression of adhesion molecules on endothelial cells (EC), as well as monocyte and leukocyte chemotactic activity in these cells. We have previously demonstrated that Lp(a), through its apo(a) moiety, increases actomyosin-driven EC contraction which, as a consequence, increases EC permeability. In this thesis, we have demonstrated a role for the strong lysine-binding site in the kringle IV type 10 domain of apo(a) in increasing EC permeability, which occurs through a Rho/Rho kinase-dependent pathway. We have further validated these findings using mouse mesenteric arteries in a pressure myograph system. We also have dissected another major signaling pathway initiated by apo(a) that involves in a disruption of adherens junctions in EC. In this pathway, apo(a)/Lp(a) activates the PI3K/Akt/GSK3β-dependent pathway to facilitate nuclear translocation of beta-catenin. In the nucleus beta-catenin induced the expression of cyclooxygenase-2 (COX-2) and the secretion of prostaglandin E2 (PGE2) from the EC. Finally, we have presented data to suggest a novel inflammatory role for apo(a) in which it induces the activation of nuclear factor-kappaB through promotion of the dissociation of IkappaB from the inactive cytoplasmic complex; this allows the nuclear translocation of NFkappaB with attendant effects on the transcription of pro-inflammatory genes. Taken together, our findings may facilitate the development of new drug targets for mitigating the harmful effects of Lp(a) on vascular EC which corresponds to an early step in the process of atherogenesis.

Analysis of Lipoprotein(a) Catabolism

Elevated plasma concentrations of lipoprotein(a) [Lp(a)] have been identified as an independent risk factor for vascular diseases including coronary heart disease and stroke. In the current study, we have examined the binding and degradation of recombinant forms of apolipoprotein(a) [r-apo(a)], the unique kringle-containing moiety of Lp(a), using a cultured cell model. We found that the incubation of human hepatoma (HepG2) cells with an iodinated 17 kringle-containing (17K) recombinant form of apo(a) resulted in a two-component binding system characterized by a high affinity (Kd = 12 nM), low capacity binding site, and a low affinity (Kd = 249 nM), high capacity binding site. We subsequently determined that the high affinity binding site on HepG2 cells corresponds to the LDL receptor. In the HepG2 cell model, association of apo(a) with the LDL receptor was shown to be dependent on the formation of Lp(a) particles from endogenous LDL. Using an apo(a) mutant incapable of binding to the high affinity site through its inability to form Lp(a) particles (17KΔLBS7,8), we further demonstrated that the LDL receptor does not participate in Lp(a) catabolism. The low affinity binding component observed on HepG2 cells, familial hypercholesterolemia (FH) fibroblasts and human embryonic kidney (HEK) 293 cells may correspond to a member(s) of the plasminogen receptor family, as binding to this site(s) was decreased by the addition of the lysine analogue epsilon-aminocaproic acid. The lysine-dependent nature of the low affinity binding site was further confirmed in HepG2 binding studies utilizing r-apo(a) species with impaired lysine binding ability. We observed a reduction maximum binding capacity for 17K r-apo(a) variants lacking the strong lysine binding site (LBS) in kringle IV type 10 (17KΔAsp) and the very weak LBS in kringle V (17KΔV). Degradation of Lp(a)/apo(a) was found to be mediated exclusively by the low affinity component on both HepG2 cells and FH fibroblasts. Fluorescence confocal microscopy, using the 17K r-apo(a) variant fused to green fluorescent protein, further confirmed that degradation by the low affinity component on HepG2 cells does not proceed by the activity of cellular lysosomes. Taken together, these data suggest a potentially significant route for Lp(a)/apo(a) clearance in vivo.

Internal mammary artery smooth muscle cells resist migration and possess high antioxidant capacity

Objective: This study investigated whether differences exist in atherogen-induced migratory behaviors and basal antioxidant enzyme capacity of vascular smooth muscle cells (VSMC) from human coronary (CA) and internal mammary (IMA) arteries. Methods: Migration experiments were performed using the Dunn chemotaxis chamber. The prooxidant [NAD(P)H oxidase] and antioxidant [NOS, superoxide dismutase, catalase and glutathione peroxidase] enzyme activities were determined by specific assays. Results: Chemotaxis experiments revealed that while both sets of VSMC migrated towards platelet-derived growth factor-BB (1-50 ng/ml) and angiotensin II (1-50 nM), neither oxidized-LDL (ox-LDL, 25-100 ng/ml) nor native LDL (100 ng/ml) affected chemotaxis in IMA VSMC. However, high dose ox-LDL produced significant chemotaxis in CAVSMC that was inhibited by pravastatin (100 nM), mevastatin (10 nM), losartan (10 nM), enalapril (1 micro.M), and MnTBAP (a free radical scavenger, 50 micro.M). Microinjection experiments with isoprenoids i.e. geranylgeranylpyrophosphate (GGPP) and farnesylpyrophosphate (FPP) showed distinct involvement of small GTPases in atherogeninduced VSMC migration. Significant increases in antioxidant enzyme activities and nitrite production along with marked decreases in NAD(P)H oxidase activity and superoxide levels were determined in IMA versus CA VSMC. Conclusions: Enhanced intrinsic antioxidant capacity may confer on IMAVSMC resistance to migration against atherogenic agents. Drugs that regulate ox-LDL or angiotensin II levels also exert antimigratory effects.

Effect of eucaloric high- and low-sucrose diets with identical macronutrient profile on insulin resistance and vascular risk - A randomized controlled trial

The long-term impact of dietary carbohydrate type, in particular sucrose, on insulin resistance and the development of diabetes and atherosclerosis is not established. Current guidelines for the healthy population advise restriction of sucrose intake. We investigated the effect of high- versus low-sucrose diet (25 vs. 10%, respectively, of total energy intake) in 13 healthy subjects aged 33 +/- 3 years (mean +/- SE), BMI 26.6 +/- 0.9 kg/m(2), in a randomized crossover design with sequential 6-week dietary interventions separated by a 4-week washout. Weight maintenance, eucaloric diets with identical macronutrient profiles and fiber content were designed. All food was weighed and distributed. Insulin action was assessed using a two-step euglycemic clamp; glycemic profiles were assessed by the continuous glucose monitoring system and vascular compliance by pulse-wave analysis. There was no change in weight across the study. Peripheral glucose uptake and suppression of endogenous glucose production were similar after each diet. Glycemic profiles and measures of vascular compliance did not change. A rise in total and LDL cholesterol was observed. In this study, a high-sucrose intake as part of an eucaloric, weight-maintaining diet had no detrimental effect on insulin sensitivity, glycemic profiles, or measures of vascular compliance in healthy nondiabetic subjects.

HDL composition and HDL antioxidant capacity in patients on regular haemodialysis

Recent evidence suggests that HDL can directly inhibit LDL oxidation, a key early stage in atherogenesis. Patients with chronic renal failure are at increased cardiovascular risk, have reduced HDL levels and altered HDL composition. We have therefore investigated whether compositional changes in HDL lead to decreased HDL antioxidant capacity in these patients. In comparison to control subject HDL, patient HDL contained less total cholesterol, cholesterol esters, phospholipids and alpha-tocopherol. LDL, HDL and LDL + HDL were standardised for protein and oxidised in the presence of Cu2+. The rate of propagation during HDL oxidation was reduced in the patient group (3.28 +/- 0.65 x 10(-5) vs. 4.60 +/- 0.97 x 10(-5) abs. U/min, P

A Dual Role for Lecithin:Cholesterol Acyltransferase (EC 2.3.1.43) in Lipoprotein Oxidation

Lecithin:cholesterol acyltransferase (LCAT) is a key enzyme involved in lipoprotein metabolism. It mediates the transesterification of free cholesterol to cholesteryl ester in an apoprotein A-I-dependent process. We have isolated purified LCAT from human plasma using anion-exchange chromatography and characterized the extracted LCAT in terms of its molecular weight, molar absorption coefficient, and enzymatic activity. The participation of LCAT in the oxidation of very low density lipoproteins (VLDL) and low-density lipoproteins (LDL) was examined by supplementing lipoproteins with exogenous LCAT over a range of protein concentrations. LCAT-depleted lipoproteins were also prepared and their oxidation kinetics examined. Our results provide evidence for a dual role for LCAT in lipoprotein oxidation, whereby it acts in a dose-responsive manner as a potent pro-oxidant during VLDL oxidation, but as an antioxidant during LDL oxidation. We believe this novel pro-oxidant effect may be attributable to the LCAT-mediated formation of oxidized cholesteryl ester in VLDL, whereas the antioxidant effect is similar to that of chain-breaking antioxidants. Thus, we have demonstrated that the high-density lipoprotein-associated enzyme LCAT may have a significant role to play in lipoprotein modification and hence atherogenesis. (C) 2007 Elsevier Inc. All rights reserved.

Role of creatine supplementation on exercise-induced cardiovascular function and oxidative stress

Many degenerative diseases are associated with increased oxidative stress. Creatine has the potential to act as an indirect and direct antioxidant; however, limited data exist to evaluate the antioxidant capabdities of creatine supplementation within in vivo human systems. This study aimed to investigate the effects of oral creatine supplementation on markers of oxidative stress and antioxidant defenses following exhaustive cycling exercise. Following preliminary testing and two additional familiarization sessions, 18 active males repeated two exhaustive incremental cycling trials (T1 and T2) separated by exactly 7 days. The subjects were assigned, in a double-blind manner, to receive either 20 g of creatine (Cr) or a placebo (P) for the 5 days preceding T2. Breath-by-breath respiratory data and heart rate were continually recorded throughout the exercise protocol and blood samples were obtained at rest (preexercise), at the end of exercise (postexercise), and the day following exercise (post24 h). Serum hypdroperoxide concentrations were elevated at postexercise by 17 +/- 5% above preexercise values (p = 0.030). However, supplementation did not influence lipid peroxidation (serum hypdroperoxide concentrations), resistance of low density lipoprotein to oxidative stress (t(1/2max) LDL oxidation) and plasma concentrations of non-enzymatic antioxidants (retinol, alpha-carotene, beta-carotene, alpha-tocopherol, gamma-tocopherol, lycopene and vitamin Q. Heart rate and oxygen uptake responses to exercise were not affected by supplementation. These findings suggest that short-term creatine supplementation does not enhance non-enzymatic antioxidant defence or protect against lipid peroxidation induced by exhaustive cycling in healthy males.

BELFAST centenarians: A Case of Optimal Cardiovascular Risk?

Introduction: Centenarians are reservoirs of genetic and environmental information to successful ageing and local centenarian groups may help us to understand some of the factors that contribute to longevity. The current centenarian cohort in Belfast survived the 1970s epidemic of death from coronary heart disease in Northern Ireland, where cardiovascular mortality was almost highest in the world. These centenarians provided an opportunity to assess biological and genetic factors important in cardiovascular risk and ageing. Methods: Thirty-five (27 female, 8 male) centenarians, participants of the Belfast Elderly Longitudinal Free-living Ageing STudy (BELFAST), were community-living and of good cognition at enrolment. Results: Centenarians showed median Body Mass Index (BMI) at 25.7, systolic blood pressure 140mmHg and diastolic blood pressure 90mmHg, and fasting glucose of 5.54 mmol/l with no sex-related difference. Lipoproteins showed median cholesterol 5.3, High Density Lipoprotein (HDL) 1.10 and Low Density Lipoprotein (LDL) 3.47umol/l respectively. Centenarian smokers showed no different blood pressure or lipid measurements compared with non-smokers. Malondialdehyde, a measure of lipid peroxidation, was low at 1.19 umol/l, and measures of antioxidant status were varied. Male centenarians did not carry any of the vascular risk genotypes studied-ApoE4 for Apolipoprotein E (ApoE), DD for Angiotensinogen Converting Enzyme (ACE) and tt for 5,10-methylenetetrahydrofolate reductase (MTFHR), though this was not true for female centenarians.. Conclusions: This small local study shows that Belfast centenarians carry a reasonably favourable risk profile, except for age, with respect to cardiovascular disease. There is also some evidence that vascular risk factors and genotypes may be tolerated differently between the male and female centenarians. Maintaining a favourable cardiovascular risk profile seems likely to improve the chance of becoming a centenarian, especially for males.

Statins for the prevention of dementia

Background: This is an update of a Cochrane review first published in 2001. At that stage there was insufficient evidence to recommend statins for the prevention of Alzheimer's disease (AD). The scope of this review has been expanded to include all forms of dementia.
Objectives: To assess the effects of statins in the prevention of dementia.
Search strategy: The Specialized Register of the Cochrane Dementia and Cognitive Improvement Group, The Cochrane Library, MEDLINE, EMBASE, PsycINFO, CINAHL and LILACS were searched on 10 October 2007 using the terms statin*, lovastatin*, pravastatin*, simvastatin*, fluvastatin*, atorvastatin* and rosuvastatin*. The CDCIG Register contains records from many healthcare databases, SIGLE, LILACS as well as many trials databases and is updated regularly.
Selection criteria: Double-blind randomized placebo-controlled trials of statins in people at risk of AD and dementia.
Data collection and analysis: Two independent reviewers extracted and assessed data independently and agreement was reached after discussion. Adverse effects were noted.
Main results: Two trials were identified with 26,340 participants; HPS 2002 and PROSPER 2002. Age range was 40-82 years across the two studies, PROSPER 2002 included 5804 patients aged 70-82 years and HPS included 20,536 patients with 5806 at least 70 years old at study entry. Mean total cholesterol 5.9 mmol/l, LDL cholesterol 3.4 mmol/l at study entry with mean reduction in LDL cholesterol of 1.0mmol/l in simvastatin treated patients compared to placebo in HPS 2002. Mean total cholesterol 5.7 mmol/l, LDL cholesterol 3.8 mmol/l at study entry with mean reduction in LDL cholesterol of 1.02 mmol/l in pravastatin treated patients compared to placebo in PROSPER 2002. Mean follow-up 3.2 years in PROSPER, 5 years in HPS 2002. Cognition was measured at different times and with different scales so could not be combined in a meta-analysis. There was no difference in incidence of dementia in HPS 2002 (31 cases in simvastatin group, 31 cases in placebo group) nor in performance on the modified Telephone Interview for Cognitive Status at final follow-up (23.7% simvastatin group cognitively impaired vs 24.2% in placebo group). There was no difference in cognition between groups either in relation to age at study entry or previous history of cerebrovascular disease. Cognitive function declined at the same rate in both treatment groups in PROSPER 2002, there was no significant difference between pravastatin treated and placebo groups in performance on letter digit codes, picture word learning test, Stroop and Mini Mental State Examination. There was no evidence that statins were detrimental to cognition.
Authors' conclusions : There is good evidence from RCTs that statins given in late life to individuals at risk of vascular disease have no effect in preventing AD or dementia. Biologically it seems feasible that statins could prevent dementia due to their role in cholesterol reduction and initial evidence from observational studies was very promising. Indication bias may have been a factor in these studies however and the evidence from subsequent RCTs has been negative.

Effect of atorvastatin on circulating hsCRP concentrations: A sub-study of the Achieve Cholesterol Targets Fast with Atorvastatin Stratified Titration (ACTFAST) study

Background: Elevated C-reactive protein (CRP) concentration is a risk factor for cardiovascular events that may add prognostic information. Statin treatment is associated with significant reductions in CRP concentrations, which appear to be unrelated to the magnitude of LDL-cholesterol reduction. We investigated the effect of atorvastatin, across its dose range, on high sensitivity (hs)CRP in subjects at high cardiovascular risk. Methods: ACTFAST was a 12 week, prospective, multicenter, open-label trial in which high-risk subjects were assigned a starting dose of atorvastatin (10, 20, 40 or 80 mg/d) based on LDL-C and status of statin use at screening (1345 statin-free [ SF] and 772 previously statin-treated [ST]). Results: At baseline, ST subjects had significantly lower hsCRP levels than SF subjects (ST group 2.31, 95% CI 2.15, 2.48 mg/L vs. SF group 3.16, 95% CI 2.98, 3.34 mg/L, p