Cholesterol and Hypertension Treatment Improve Coronary Risk Prediction but Not Time-Dependent Covariates or Competing Risks

Background and Aims

Cardiovascular (CV) risk functions are the recommended tool to identify high-risk individuals. However, their discrimination ability is not optimal. While the effect of biomarkers in CV risk prediction has been extensively studied, there are no data on CV risk functions including time-dependent covariates together with other variables. Our aim was to examine the effect of including time-dependent covariates, competing risks, and treatments in coronary risk prediction.

Methods

Participants from the REGICOR population cohorts (North-Eastern Spain) aged 35-74 years without previous history of cardiovascular disease were included (n = 8470). Coronary and stroke events and mortality due to other CV causes or to cancer were recorded during follow-up (median = 12.6 years). A multi-state Markov model was constructed to include competing risks and time-dependent classical risk factors and treatments (2 measurements). This model was compared to Cox models with basal measurement of classical risk factors, treatments, or competing risks. Models were cross-validated and compared for discrimination (area under ROC curve), calibration (Hosmer-Lemeshow test), and reclassification (categorical net reclassification index).

Results

Cancer mortality was the highest cumulative-incidence event. Adding cholesterol and hypertension treatment to classical risk factors improved discrimination of coronary events by 2% and reclassification by 7-9%. The inclusion of competing risks and/or 2 measurements of risk factors provided similar coronary event prediction, compared to a single measurement of risk factors.

Conclusion

Coronary risk prediction improves when cholesterol and hypertension treatment are included in risk functions. Coronary risk prediction does not improve with 2 measurements of covariates or inclusion of competing risks.

Cholesterol and hypertension treatment but not time-dependent covariates or competing risks improve coronary risk prediction: the REGICOR study

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Carlos III Health Institute Agency for Management of University and Research Grants

Background

Cardiovascular (CV) risk functions are the recommended tool to identify high-risk individuals. However, discrimination of CV risk functions is not optimal. While the effect of biomarkers in CV risk prediction has been extensively studied, there is no data of CV risk functions including time-dependent covariates, competing risks and treatments.

Aim

To examine the effect of including time-dependent covariates, competing risks and treatments in CV risk prediction.

Methods

Participants from the REGICOR population cohorts (North-Eastern Spain) aged 35-74 years without previous history of cardiovascular disease were included (n=8,470). Coronary and stroke events, and mortality due to other CV causes or to cancer were recorded during the follow-up (median=12.6 years). A multi-state Markov model was constructed to include competing risks and time-dependent classical risk factors and treatments (2 measurements). This model was compared to Cox models with the basal measurement of classical risk factors, treatments or competing risks. Models were cross-validated and compared by their discrimination (area under the ROC curve), calibration (Hosmer-Lemeshow test) and reclassification (categorical net reclassification index).

Results

Cancer mortality was the event with the highest cumulative incidence. In coronary event prediction, cholesterol and hypertension treatment addition to classical risk factors, improved significantly discrimination by 2% and reclassification by 7-9%. In stroke event prediction, inclusion of time-dependent covariates decreased significantly discrimination by 3-5%.

Conclusion

Coronary risk prediction improves when cholesterol and hypertension treatment are included in risk functions. Coronary/stroke prediction does not improve with 2 measurements of covariates or with competing risks.

Validity and trends of myocardial infarction incidence and case-fatality estimated from linked administrative databases

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): CIBERCV of cardiovascular diseases; CIBERESP.

OnBehalf

REGICOR investigators

Background

Although myocardial infarction (MI) severity trends are systematically measured with mortality rates, MI incidence trends and the precision of its estimation by linkage of anonymized electronic databases are relatively untested. We validated a linked-data method (LDM) to estimate a population MI incidence and case-fatality, and to analyse the 1990-2016 trends in North-Eastern Spain. 

Methods

LDM consisted of linking MI hospital discharges (n = 4,533,981) and mortality registry data (n = 40,676) for 2008-2016, selecting key MI diagnostic codes. The prospective REGICOR study, including all MI cases in Girona, 1990-2009, was used as the gold standard for validation purposes. Standardized MI cumulated incidence and 28-day case fatality for population aged 35-74 years was calculated, 1990-2016 trends were analysed by linear and joinpoint regression and annual percentage change (APC).

Results

LDM and REGICOR MI incidence and case-fatality estimates were similar for 2008-09 (Table). LDM MI incidence and case-fatality significantly decreased: APC 1990-2016 [95% CI]) was -1.8 [-2.6;-0.9] in women, and APC 2002-2016  -2.8 [-3.8;-1.8] in men; case-fatality APC 1990-2016 was -4.7% [-5.7;-3.8] in women and APC 1995-2005 -6.5%[-8.5;-4.5] in men. 

Conclusions

LDM in population aged 35-74 reliably estimated MI incidence and case-fatality. MI incidence and case-fatality significantly decreased after 1990.

Comparative analysis of REGICOR vs LDM REGICOR 2008-2009 LDM 2008-2009 Estimate 95% CI Estimate 95% CI P-Value Cumulated incidence Men 245.4 228.3; 262.5 239.7 222.5; 256.3 0.626 Women 61.1 52.6; 69.6 58.2 49.9; 66.4 0.626 Overall 28-day case-fatality Men 23.5% 19.7; 27.2 21.3% 17.8; 24.9 0.422 Women 19.3% 6.7; 31.9 17.7% 6.3; 29.1 0.855 In-hospital case-fatality Men 6.9% 4.8; 9.0 5.7% 3.8; 7.6 0.394 Women 5.0% 1.9; 8.2 3.7% 1.0; 6.5 0.540 Pre-hospital case-fatality Men 16.5% 11.8; 21.3 15.6% 11.2; 20.1 0.791 Women 14.2 % 6.6; 21.9 14.0% 6.3; 21.7 0.961 CI Confidence Interval

In Vitro Assay of Quinoa (Chenopodium quinoa Willd.) and Lupin (Lupinus spp.) Extracts on Human Platelet Aggregation

Cardiovascular disease (CVD) is the leading cause of death throughout the world. A major risk factor for CVD is platelet aggregation. Various plant extracts exhibit anti-aggregatory action in vitro. The dietary intake of traditional plant crops such as quinoa (Chenopodium quinoa Willd) and lupin (Lupinus spp., Fabaceae family), highly recognized for their high nutritional value, is increasing worldwide. The aim of the study was to assay possible antiplatelet effects of quinoa and lupin bean extracts in vitro. The proximate chemical composition of quinoa grains and the three most widely known lupin cultivars: blue (L. angustifolius), yellow (L. luteus or mutabilis) and white (L. albus) grown in Chile were analyzed. The anti-aggregation activity of the ethanol extracts of the crops was assayed using flow cytometry in ADP-stimulated human platelets, and their inhibition of the maximal platelet aggregation was measured. All the lupin extracts exhibited a significant anti-aggregatory effect (p < 0.0001), while quinoa extracts did not exert this effect compared to control platelets. In conclusion, lupin beans extracts exhibited an anti-aggregatory effect on activated human platelets.

Decoding the Role of Platelets and Related MicroRNAs in Aging and Neurodegenerative Disorders

Platelets are anucleate cells that circulate in blood and are essential components of the hemostatic system. During aging, platelet numbers decrease and their aggregation capacity is reduced. Platelet dysfunctions associated with aging can be linked to molecular alterations affecting several cellular systems that include cytoskeleton rearrangements, signal transduction, vesicular trafficking, and protein degradation. Age platelets may adopt a phenotype characterized by robust secretion of extracellular vesicles that could in turn account for about 70-90% of blood circulating vesicles. Interestingly these extracellular vesicles are loaded with messenger RNAs and microRNAs that may have a profound impact on protein physiology at the systems level. Age platelet dysfunction is also associated with accumulation of reactive oxygen species. Thereby understanding the mechanisms of aging in platelets as well as their age-dependent dysfunctions may be of interest when evaluating the contribution of aging to the onset of age-dependent pathologies, such as those affecting the nervous system. In this review we summarize the findings that link platelet dysfunctions to neurodegenerative diseases including Alzheimer's Disease, Parkinson's Disease, Multiple Sclerosis, Huntington's Disease, and Amyotrophic Lateral Sclerosis. We discuss the role of platelets as drivers of protein dysfunctions observed in these pathologies, their association with aging and the potential clinical significance of platelets, and related miRNAs, as peripheral biomarkers for diagnosis and prognosis of neurodegenerative diseases.

Chemical Characterization and Antiplatelet Potential of Bioactive Extract from Tomato Pomace (Byproduct of Tomato Paste)

We examined the ability of tomato pomace extract (by-product) to affect platelet aggregation in healthy humans (clinical pilot study). In phase 1 the tolerance of participants (n = 15; 5 per dose level) ingesting tomato pomace extract across three dose levels (1, 2.5, and 10 g) was evaluated. Phase 2 was a single-blind, placebo-controlled, parallel design human (male, n = 99; 33 per group) pilot intervention trial investigating the acute and repeated dose effects (5 days) of different doses of tomato pomace extract (1 g, 2.5 g or placebo) on platelet aggregation ex vivo. Various flavonoids (coumaric acid, floridzin, floretin, procyanidin B₂, luteolin-7-O-glucoside, kaempferol, and quercitin) and nucleosides (adenosine, inosine, and guanosine) were identified in the tomato pomace extract. The clinical study showed that the daily consumption of 1 g of aqueous extract of tomato pomace for 5 days exerted an inhibitory activity on platelet aggregation.

Anti-aggregation effect on platelets of Indiplon a hypnotic sedative non-benzodiazepine drug

Cardiovascular diseases are one of the main public health problems, and many of them, their pathophysiology involves alterations in platelet activity. Platelet activation is an essential event that is regulated by the intracellular concentrations of Ca2+ and cAMP. Interestingly, it has been shown that the activation of adenosine A2A receptors increases cAMP levels and produces the inhibition of platelet aggregation, which appears as a potential target for regulation of platelet activity. Therefore, we tried to activate A2A receptors using Indiplon, a drug developed for the treatment of insomnia, and analyze its effect on platelet activity in vitro. Our results indicate that Indiplon is able to interact in silico with the adenosine A2A receptor (ΔG_bind of -73.321 kcal/mol, similar to that obtained with adenosine), which is involved in the regulation of platelet cAMP levels. In functional studies using PRP, a reduction in platelet aggregation induced by ADP was observed in the presence of Indiplon at 500 μM with a percentage of inhibition 70%, where the use of specific inhibitors (ZM241385 and MSX-2) of the A2A receptor also blocked these effects reducing the percentage of inhibition to 41% and 34.1%, respectively. Also, the use of Indiplon produced a decrease in the expression in the membrane of P-selectin. Thus, Indiplon acts as an A2A receptor agonist and whose activation results in inhibition of platelet aggregation and activation, showing a possible cardiovascular protective role.

The cAMP/PKA Pathway Inhibits Beta-amyloid Peptide Release from Human Platelets

The main component of Alzheimer's disease (AD) is the amyloid-beta peptide (Aβ), the brain of these patients is characterized by deposits in the parenchyma and cerebral blood vessels known as cerebral amyloid angiopathy (CAA). On the other hand, the platelets are the major source of the Aβ peptide in circulation and once secreted can activate the platelets and endothelial cells producing the secretion of several inflammatory mediators that finally end up unchaining the CAA and later AD. In the present study we demonstrate that cAMP/PKA pathway plays key roles in the regulation of calpain activation and secretion of Aβ in human platelets. We confirmed that inhibition of platelet functionality occurred when platelets were incubated with forskolin (molecule that rapidly increased cAMP levels). In this sense we found that platelets pre-incubated with forskolin (20 μM) present a complete inhibition of calpain activity and this effect is reversed using an inhibitor of protein kinase A. Consequentially, when platelets were inhibited by forskolin a reduction in the processing of the APP with the consequent decrease in the Aβ peptide secretion was observed. Therefore our study provides novel insight in relation to the mechanism of processing and release of the Aβ peptide from human platelets.

Validity of the Physical Activity Questionnaires IPAQ-SF and GPAQ for Cancer Survivors: Insights from a Spanish Cohort

Regular physical activity (PA) decreases mortality risk in survivors of breast and colorectal cancer. Such impacts of exercise have prompted initiatives designed both to promote and adequately monitor PA in cancer survivors. This study examines the validity of 2 widely used self-report methods for PA determination, the International Physical Activity Questionnaire short version (IPAQ-SF) and Global Physical Activity Questionnaire (GPAQ). Both instruments were compared with the triaxial accelerometry (Actigraph) method as an objective reference standard. Study participants were 204 cancer survivors (both sexes, aged 18-79 years). Compared with accelerometry, both questionnaires significantly overestimated PA levels (across all intensities) and underestimated physical inactivity levels. No differences were detected between the 2 questionnaires except for a shorter inactivity time estimated by GPAQ (p=0.001). The Bland and Altman method confirmed that both questionnaires overestimated all PA levels. Receiver operating characteristic (ROC) analysis classified IPAQ and GPAQ as fair and poor predictors, respectively, of the proportions of survivors fulfilling international PA recommendations (≥150 min·week^-1 of moderate-vigorous PA). IPAQ-SF showed a higher sensitivity but lower specificity than GPAQ. Our data do not support the use of IPAQ-SF or GPAQ to determine PA or inactivity levels in cancer survivors.

The influence of ethnicity on warfarin dosage requirements in the chilean population

Background

Vitamin K antagonists are drugs that are widely prescribed around the world and their use has helped improve the prognosis of patients with thromboembolic disease. However, a high interindividual variability has been observed in dosage requirements to reach the desired anticoagulation range that could be due to environmental and genetic factors. Studies suggest that ethnicity influences coumarin response, supporting the observed differences in dose requirements across various populations. Studies using mitochondrial DNA (mtDNA) markers have suggested that the Chilean population has a predominantly Amerindian genetic pool.

Objective

To evaluate the influence of ethnicity, defined by the presence of Amerindian mtDNA haplogroups, on the variability in therapeutic response to warfarin in the Chilean population.

Methods

A total of 191 patients treated with warfarin were included in this study. Analysis of the mitochondrial genome for detecting the presence of Amerindian mtDNA haplogroups was performed using polymerase chain reaction and polymerase chain reaction restriction fragment length polymorphism techniques. The evaluation of warfarin requirements according to each haplogroup was performed by ANOVA with a 95% CI and assuming statistical significance at P < 0.05.

Results

Based on the presence of an mtDNA haplogroup, 91% of the Chilean population had an Amerindian background. There were no significant differences in warfarin dosage requirements among the different Amerindian haplogroups (P = 0.083).

Conclusions

The presence of Amerindian mtDNA haplogroup does not influence warfarin dosage requirements in the Chilean population.

Abstract P3-08-17: Objectively measured physical activity in breast cancer survivors

Background: Obesity and physical inactivity are poor prognostic indicators for breast cancer (BC). Cardiorespiratory fitness (VO2max) is a good predictor of survival. Despite preserved LVEF, cardiorespiratory function is impaired in women with breast cancer after the completion of adjuvant therapy. International organizations recommend at least 150 minutes per week of moderate-vigorous physical activity (MVPA). Some studies show that a minority of cancer survivors are meeting the PA recommendations. A limitation of physical activity (PA) research has been the use of self-reported measures.

Eligibility criteria: 1) Age 18-79, 2) Able to walk a mile, 3) More than one year from diagnosis, 4) More than 3 months since the last therapy, 5) No evidence of disease.

Aims: Objective assessment of physical activity in breast cancer survivors. Adherence to international recommendations.

Material and methods: PA was evaluated through accelerometry (600 minutes per day, 5 days per week, 2 week-end days were required to consider as valid accelerometry values). Cardiorespiratory fitness was assessed through the “one-mile test”.

Results: 92 women (W) with BC history were included. 86 W were evaluable for accelerometry. 85 W were evaluable for VO2max. Age: 54.02 years (33-77), BMI: 27.89 (SD 8.89), waist perimeter: 89.74 cm (SD 17.37), median time from diagnosis 3.94 years, treatment with anthracyclines 55 W (63.9%), radiotherapy 69 W (80.23%). Accelerometry (86W): Average weekly time MVPA 351.14 min/wk (SD: 168.98). 76 (88%) met international recommendations of PA. Women previously treated with anthracyclines (47 W; 340.25 min/wk), radiotherapy (59 w; 343 min/wk) and both (48 W; 331 min/wk) exercised less than women who did not receive these therapies (8 W; 386 min/wk). This association was not statistically significant.

Average VO2max was 24.8 ml/kg/min (SD: 7.6).There was a significant effect of anthracyclines for VO2 max. Women not treated with anthracyclines had a VO2max: 26.41 whereas treated W had VO2max 22.08 ml/kg/min.

Discussion: A cohort of Spanish women met international recommendations of PA when it was objectively assessed. This cohort exhibited a poor cardiometabolic and cardiorespiratory profile. Previous exposure to anthracyclines predicted a poorer cardiorespiratory fitness. Specific research to investigate the role of exercise to mitigate that dysfunction in breast cancer survivors is warranted.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P3-08-17.

Protective mechanisms of adenosine 5'-monophosphate in platelet activation and thrombus formation

Platelet activation is relevant to a variety of acute thrombotic events. We sought to examine adenosine 5'-monophosphate (AMP) mechanisms of action in preventing platelet activation, thrombus formation and platelet-related inflammatory response. We assessed the effect of AMP on 1) P-selectin expression and GPIIb/IIIa activation by flow cytometry; 2) Platelet aggregation and ATP secretion induced by ADP, collagen, TRAP-6, convulxin and thrombin; 3) Platelet rolling and firm adhesion, and platelet-leukocyte interactions under flow-controlled conditions; and, 4) Platelet cAMP levels, sP-selectin, sCD40L, IL-1β, TGF-β1 and CCL5 release, PDE3A activity and PKA phosphorylation. The effect of AMP on in vivo thrombus formation was also evaluated in a murine model. The AMP docking with respect to A2 adenosine receptor was determined by homology. AMP concentration-dependently (0.1 to 3 mmol/l) inhibited P-selectin expression and GPIIb/IIIa activation, platelet secretion and aggregation induced by ADP, collagen, TRAP-6 and convulxin, and diminished platelet rolling and firm adhesion. Furthermore, AMP induced a marked increase in the rolling speed of leukocytes retained on the platelet surface. At these concentrations AMP significantly decreased inflammatory mediator from platelet, increased intraplatelet cAMP levels and inhibited PDE3A activity. Interestingly, SQ22536, ZM241385 and SCH58261 attenuated the antiplatelet effect of AMP. Docking experiments revealed that AMP had the same orientation that adenosine inside the A2 adenosine receptor binding pocket. These in vitro antithrombotic properties were further supported in an in vivo model of thrombosis. Considering the successful use of combined antiplatelet therapy, AMP may be further developed as a novel antiplatelet agent.

Synthetic isoxazole as antiplatelet agent

Abstract Nine synthetic isoxazoles were evaluated as antiplatelet agents and studied the possible mechanism of more active compound. The initial screening was evaluating all compounds against platelet aggregation assays. The most active compound was isoxazole 8 showing an inhibition of platelet aggregation around 70%. In subsequent experiments, ADP and collagen were used as agonists to explore the possible inhibitory mechanisms of isoxazole 8 in platelet aggregation and secretion. We reported the effect of isoxazole 8 for reducing the expression of inflammatory markers, such as soluble CD40 ligand (sCD40L) and soluble P-selectin (sP-selectin), on activated platelets. Of this form, an inhibition of sCD40L and sP-selectin can prevent the onset of an atherosclerotic lesion.

A high fat diet in CF-1 mice: An experimental model for metabolic syndrome

Cardiovascular diseases account for the majority of deaths worldwide. Many of their risk factors have been identified but, for their continued study, research centering on new murine models is of interest. In this study, a high fat diet (HFD) and a normal diet (ND) (25 and 4.4% fat, respectively) were tested over a 40-day period to induce the same metabolic alterations in CF-1 mice in two separate experiments. The parameters measured for these effects corresponded to the weight of ingested food and water, to the weight of the mice and their selected organs (adipose tissue, gastrocnemius, liver and heart), to their biochemical profile (glycemia, blood uric nitrogen, uric acid, triglycerides, cholesterol, proteins and albumin) and to the percentage of fat in their livers. The biochemical profile of the CF-1 mice fed a diet high in fat but balanced in proteins (16.9%) showed statistically significant increases in glycemia, cholesterol and triglyceride levels. A statistically significant increase in the weight of adipose tissue was also observed. No statistically significant differences were observed in the muscular mass of either of the groups of mice, but a high percentage of fat was found in the liver. The results lead to the conclusion that CF-1 mice fed a HFD develop metabolic alterations that correspond to an equivalent metabolic syndrome. This is important in the evaluation of the effects of various interventions, such as food, exercise and molecules, on metabolic alterations in mice induced by the intake of a HFD.

High levels of hsCRP are associated with carbohydrate metabolism disorder

AIM

To determine risk parameters associated with high values of high sensitive C-reactive protein (hsCRP) in subjects with different glucose fasting levels.

METHODS

Anthropometric parameters, arterial pressure, glycemia, lipid profile, uric acid, and hsCRP were studied in a population of 513 individuals between 40 and 65 years.

RESULTS

In total, 349 (68.0%) were normoglycemic (NG); 113 (22.0%) had impaired fasting glucose (IFG); and 51 (9.9%) were diabetic subjects. A multivariate linear regression analysis showed that the natural logarithm of hsCRP was associated significantly with glycemia levels (P = 0.009), uric acid (P = 0.001), diastolic blood pressure (P = 0.011), smoking habit (P = 0.021), BMI (P<0.001), and sex (P<0.001). One-third of the NG subjects had high hsCRP levels. A multiple logistic regression analysis showed that sex and BMI were variables related to high levels of hsCRP in subjects with IFG and NG. In NG subjects, uric acid levels were associated with risk of presenting high hsCRP levels and were higher in women than men. In NG women, ROC curves analysis identified a uric acid level of 3.9  mg/dl as a cut-off point to predict a high value of hsCRP. Those individuals with uric acid values higher than 3.9 mg/dl and normal glycemia had 3.5-fold more risk of having hsCRP levels over 3.0 mg/l.

CONCLUSIONS

We sustain that high levels of hsCRP are associated with disturbance in carbohydrate metabolism. In addition, we believe that in low cardiovascular risk population, such as NG women, uric acid levels above 3.9 mg/dl might represent a signal of possible pro-inflammatory state and cardiovascular risk.

High-sensitivity C-reactive protein and liver enzymes in individuals with Metabolic Syndrome in Talca, Chile

Metabolic syndrome (MS) is a core set of disorders, including abdominal obesity, dyslipidemia, hypertension and hypertriglyceridemia that together predict the development of diabetes type 2 and cardiovascular disease. This study investigated the relationship between liver enzyme levels and high-sensitivity C-reactive protein (hs-CRP) in subjects with and without MS. Alanine-aminotransferase (ALAT), aspartate-aminotransferase (ASAT), γ-glutamyl transferase (GGT) and hs-CRP were measured in 510 subjects, aged 40 to 65 years old. Patients were selected from 1007 subjects from the Research Program for Cardiovascular Disease Risk Factors in Talca, Chile. Results showed that women with MS presented higher liver enzyme levels than those who did not have MS. This was not observed in male patients for the enzymes ALAT and ASAT. However, GGT and hs-PCR levels were higher in male and female patients with MS than in those without MS. In conclusion, it is important to search for the presence of MS when diagnosing fatty liver. Moreover, the presence of liver disease in patients with MS should be further investigated.

Pathophysiology of the proatherothrombotic state in the metabolic syndrome

Obesity and insulin resistance are very frequently associated to the metabolic syndrome (MetS), play a pivotal role in the development of type 2 diabetes mellitus (T2DM) and increases the risk of cardiovascular disease. Although it varies among ethnic groups, the worldwide prevalence of MetS is 23% in young adults and increases with age. Remarkably, the prevalence of MetS is expected to rise during the next decades due to the acquisition of unhealthy life-style habits (sedentarism, smoking, unhealthy diet). A major pathological alteration present in the MetS is a prothrombotic state resulting from endothelial dysfunction and hypercoagulability produced by a dysbalance of coagulation factors and proteins regulating fibrinolysis. Although intensive research in recent years has identified a number of prothrombotic alterations in MetS patients, a better understanding of the molecular mechanisms underlying the relationship between MetS and atherotrombosis is required to improve prevention and treatment. In this review we discuss the main alterations in the endothelial function, coagulation cascade, fibrinolysis and platelet function promoting atherothrombosis in MetS and available mouse models exhibiting alterations in atherothrombosis.

Antiphospholipid syndrome: a comprehensive review of a complex and multisystemic disease

The antiphospholipid syndrome (APS) is an acquired thombophilia, which is characterized by one or more thrombotic episodes and obstetric complications in the presence of antiphospholipid (aPL) antibodies (Abs). APL Abs are detected by laboratory tests such as lupus anticoagulant (LAC), anticardiolipin (aCL) and anti-Beta2-glycoprotein I (Beta2GPI) Abs. This article reviews the most current aspects of APS with emphasis on the pathophysiology of the disease, clinical manifestations, laboratory tests, and current modalities of treatment.

Antiphospholipid antibodies and the antiphospholipid syndrome: pathogenic mechanisms

Antiphospholipid antibodies (Abs) are associated with thrombosis and are a risk factor for recurrent pregnancy loss and obstetric complications in patients with the antiphospholipid syndrome. It is generally accepted that the major autoantigen for aPL Abs is beta (2) glycoprotein I, which mediates the binding of aPL Abs to target cells (i.e., endothelial cells, monocytes, platelets, trophoblasts, etc.) leading to thrombosis and fetal loss. This article addresses molecular events triggered by aPL Abs on endothelial cells, platelets, and monocytes and complement activation, as well as a review of the current knowledge with regard to the putative receptor(s) recognized by aPL Abs on target cells as well as novel mechanisms that involve fibrinolytic processes. A section is devoted to the description of thrombotic and inflammatory processes that lead to obstetric complications mediated by aPL Abs. Based on experimental evidence using in vitro and in vivo models, new targeted therapies for treatment and/or prevention of thrombosis and pregnancy loss in antiphospholipid syndrome are proposed.

Evaluation of metabolic syndrome in adults of Talca city, Chile

OBJECTIVE

Insulin resistance (IR) is an important risk factor for type 2 Diabetes Mellitus (DM2) and cardiovascular disease (CVD). Metabolic Syndrome (MS) is a clustering of metabolic alterations associated to IR; however, there is no international consensus for defining its diagnosis. Our objective was to evaluate the prevalence and characteristics of MS identified by the ATP III and IDF criteria in adults from Talca city.

RESEARCH AND METHODS

We studied 1007 individuals, aged 18-74, and residents from Talca. MS subjects were defined according to ATP III (three altered factors) and IDF criteria (patients with waist circumference >80/90 cm (W/M) and two others altered factors).

RESULTS

The prevalence of metabolic syndrome according to the IDF and ATP III criteria was 36.4% and 29.5%, respectively after adjustment for age and sex. The agreement for both criteria was 89%. The prevalence in men was higher than in women for both MS definitions, although not significant. MS probability increased with age, and the highest risk was in the 57-68 age group (ATP-MS) and 53-72 age group (IDF-MS). Hypertension, high triglycerides and abdominal obesity are the most frequent alterations in MS.

CONCLUSION

MS prevalence in adults was higher when diagnosed with IDF than with ATP criterion; in both, age is directly related with the MS presence. The MS subjects showed higher levels of blood pressure, waist circumference and plasma triglycerides. Considering our results, it is worrisome that one third of our population has a high risk of developing DM2 and CVD in the future.

Antiphospholipid antibodies in Chilean patients with systemic lupus erythematosus

Antiphospholipid antibodies (aPLs) are a heterogeneous family of antibodies found in autoimmune disorders, infectious diseases, and other situations. The presence of different aPLs has been associated with various clinical manifestations of the antiphospholipid syndrome (APS). The objective of this study was to investigate the prevalence of aPLs in a group of 90 Chilean patients with systemic lupus erytematosus (SLE) and 90 healthy controls. We measured anticardiolipin antibodies (aCLs), antiphosphatidylserine antibodies (aPSs), anti-beta(2) glycoprotein I antibodies (anti-beta(2)GPIs), and antiprothrombin antibodies (aPTs) with an enzyme-linked immunosorbent technique using "in-house" assays. Fifty-four of 90 SLE patients (60.0%) had some type of aPL. Forty of 90 (44.4%) were positive for aCLs, 9 of 61 (14.8%) had aPSs, 21 of 90 (23.3%) had anti-beta(2)GPIs, and 18 of 90 (20.0%) had aPTs. In the control group, prevalences were as follows: aCLs, 3.3%; aPSs, 1.1%; anti-beta(2)GPIs, 1.1%; aPTs, 2.2%. In most cases, values were in the low-positive range. Of all aPL detected, 29.5% was of the IgG isotype, 37.5% IgM, and 33.0% IgA. We observed a correlation between aCLs and aPSs and of these antibodies with anti-beta(2)GPIs and aPTs but not between anti-beta(2)GPIs and aPTs. Our results show a high prevalence of aPLs in SLE patients. An association between different specificities and isotypes of aPLs was also observed.

Platelet aging in vivo is associated with loss of membrane phospholipid asymmetry

The mechanism(s) involved in the clearance of senescent platelets are largely unknown. The loss of membrane phospholipid (PL) asymmetry, with phosphatidylserine (PS) exposure appears to be an important signal for the ingestion by macrophages of apoptotic nucleated cells and it has also been suggested as a signal for the removal of aged erythrocytes. Accordingly, it seems possible that the clearance of normal aged platelets from circulation might be triggered by PS exposure. To investigate this, we determined PS exposure in human aging platelets taking advantage of the relationship between platelet density and platelet age and in dog platelets in a model of platelet aging in vivo. PS exposure was determined in two experimental conditions: 1) human platelet density subpopulations obtained by centrifugation in arabinogalactan gradients; 2) circulating canine platelets during decline in platelet count after suppression of thrombopoiesis following estradiol injection. PS exposure was determined by flow cytometry after labeling the cells with FITC-conjugated annexin V. The proportion of human platelets with exposed PS was significantly higher in high density (HD) platelets compared to low density (LD) platelets (11.3 +/- 8.0% vs 5.2 +/- 3.7%; p <0.05, respectively). In dogs, the proportion of cells with exposed PS rises dramatically with age, from 3.1 +/- 0.4% before to 17.7 +/- 12.3% ten days after estradiol injection. These findings suggest that platelet aging is associated with loss of phospholipid asymmetry and PS exposure on the outer leaflet of cell membrane, which may play an important role in the recognition and subsequent removal of senescent platelets.

[Effect of the prolonged use of intrauterine devices and oral contraceptive on iron nutrition]

The aim of this work was to study the effect of prolonged use of intrauterine devices (IUD) and oral contraceptives (OCO) normally prescribed at outpatient clinics of the Health Service on iron nutrition. Two hundred twenty three healthy women, aged 20 to 39 years were studied. Of these, 100 were using IUD and 97 OCO for three to five years and 26 were not using any pharmacological or mechanical contraceptive method (control group). Serum ferritin was significantly higher in the OCO group compared to IUD and control groups (58.9 +/- 2.2; 26.2 +/- 2.1 and 21.1 +/- 2.4 ng/ml respectively). There was a positive correlation between serum ferritin and hemoglobin in IUD and control groups and between ferritin and transferrin saturation in the OCO and control groups. The frequency of storage iron depletion (defined as a serum ferritin < 12 ng/ml) was 6.3, 0 and 25% in the IUD, OCO and control groups respectively. The numbers for iron-deficient erythropoiesis (defined as a transferrin saturation < 15%) were 7, 3 and 4% and for iron deficiency anemia, 6.5, 0 and 8%. It is concluded that the chronic use of IUDs leads to iron depletion and that measures to improve iron nutrition among women using them should be adopted.

[Hemoglobin, serum iron and transferrin saturation among users of intrauterine devices and oral contraceptive agents]

We studied 60 females using either intrauterine device or taking oral contraceptive pills. Hemoglobin, serum iron, total iron binding capacity and saturation of transferrin were determined before and 4 and 10 months after starting a responsible paternity program. Women with a basal hemoglobin level below 12 g/dl were excluded. Age, parity and hematologic parameters were similar for both groups. A significant decrease in hemoglobin level and saturation of transferrin was observed at 10 months in intrauterine device users (13.6 to 13.1 g/dl and 36.2 to 26.9%, respectively). Use of oral contraceptive pills was not associated to hemoglobin decrease but a significant rise in saturation of transferrin was observed (36.2 to 43.9%, p less than 0.05).