Amalia Dionyssiou-Asteriou

Circulating oxidized low density lipoprotein, autoantibodies against them and homocysteine serum levels in diagnosis and estimation of severity of coronary artery disease

The oxidative hypothesis of atherosclerosis proposes that oxidative modification of low density lipoprotein (LDL) plays a critical role in atherogenesis. The evaluation of LDL oxidation in vivo is therefore very important. However, data concerning the evaluation of the above biochemical marker is very limited in clinical practice. This study was conducted to test the hypothesis that plasma levels of ox-LDL reflect atherosclerosis and determine the clinical significance in the measurement of circulating ox-LDL and autoantibodies against them as well as their correlation with homocysteine and lipid parameters in the diagnosis and severity of coronary heart disease. A total of 273 individuals were examined: 41 suffering from unstable angina pectoris (UAP), 62 from stable angina pectoris (SAP) and 170 healthy control subjects. We used a sensitive method for detecting ox-LDL that is based on a direct sandwich technique (ELISA) in which two monoclonal antibodies are directed against separate antigenic determinants on the oxidized apolipoprotein-B molecule along with another enzyme immunoassay designed to determine human antibodies to oxidized LDL (anti-oxLDL) directly in serum. Total homocysteine (HCY) was evaluated by means of a fully automated fluorescence polarization immunoassay. Patients with UAP exhibited marked elevations in oxLDL levels as compared to patients with SAP (161.2±28.4 vs. 119.2±26.6, p<0.001) and the control subjects (67±18.8, p<0.001). The difference in oxLDL levels between patients with SAP and the control group was also statistically significant. Similarly, patients with UAP showed marked elevations in anti-oxLDL antibodies compared to both patients with SAP (602.2±62.2 vs. 510.8±50.3, p<0.001) and control subjects (368±79.6, p<0.001). The difference in anti-oxLDL levels between patients with SAP and the controls was also statistically significant. OxLDL levels were not correlated with age in any of the groups studied. Triglycerides, LDL-cholesterol and total cholesterol were elevated in patients with UAP as opposed to patients with SAP and the control subjects, while HDL levels were elevated in the control subjects when compared to patients with SAP and UAP. Homocysteine levels were elevated in patients suffering from UAP and SAP when compared to healthy subjects. Patients with UAP or SAP did not differ on homocysteine levels. Our findings demonstrate the presence of oxLDL in vivo, its strong association with coronary artery disease as well as with the severity of the clinical presentation.

Stimulation of innate immunity by susceptible and multidrug-resistant Pseudomonas aeruginosa: an in vitro and in vivo study

In attempt to investigate the stimulatory effect of Pseudomonas aeruginosa on innate immunity and to correlate it to its level of resistance to antimicrobials, 20 isolates were applied; 8 isolates were susceptible and 12 multidrug‐resistant. Genetic diversity was defined by PFGE. Human monocytes of two healthy volunteers were in vitro stimulated by the isolates for the production of pro‐inflammatory (TNF‐α, IL‐1β, IL‐6, IL‐8 and IL‐12) and anti‐inflammatory cytokines (IL‐10), of malondialdehyde and of procalcitonin. Cytokines were estimated by EIA, malondialdehyde by the thiobarbiturate assay and procalcitonin by an immunochemiluminometric assay. Survival of 48 Wistar rats was recorded after induction of sepsis by the intraperitoneal injection of three susceptible and three multidrug‐resistant isolates. To test whether comparative effect of the latter isolates on survival correlates with any difference of monocyte‐mediated release of pro‐inflammatory mediators, monocytes of two rats were in vitro stimulated for the production of TNF‐α and of malondialdehyde. In vitro stimulation of human monocytes by the susceptible isolates elicited elevated production of malondiadeheyde, of IL‐1β and of IL‐6 compared to stimulation by multidrug‐resistant isolates. Similar differences were found for TNF‐α and IL‐8, but they were not statistically significant. Production of IL‐10 and IL‐12 was not detected after stimulation with any isolate. Levels of procalcitonin were similar after induction with either susceptible or multidrug‐resistant isolates. Mean survival of animals was 7·56, 21·80 and 55·20 h, respectively, after challenge by the susceptible isolates and 28·89, 61·8 and more than 120 h, respectively, after challenge by the multidrug‐resistant isolates. Differences of survival were accompanied by greater rodent monocyte‐release of TNF‐α and malondialdehyde after stimulation by the susceptible isolates compared to multidrug‐resistant ones. It is concluded that considerable differences are encountered on the stimulation of human monocytes by susceptible and resistant isolates of Pseudomonas aeruginosa. These results correlate with in vivo evidence and might influence decision on therapeutics.

Adiponectin and resistin are associated with risk for myelodysplastic syndrome, independently from the insulin-like growth factor-I (IGF-I) system

AIM Obesity has been implicated in the aetiology of myelogenous leukaemia and myelodysplasia (MDS). We hypothesised that altered secretion of adiponectin and resistin may underlie this association. We thus investigated the role of both total and high molecular weight (HMW) adiponectin and resistin in MDS. METHODS In a case-control study, we studied 101 cases with incident, histologically confirmed primary MDS and 101 controls matched on gender and age between 2004 and 2007. Total and HMW adiponectin, resistin, insulin-like growth factor-I (IGF-I) and insulin-like growth factor binding protein (IGFBP-3) were determined. RESULTS Lower serum total or HMW adiponectin and/or resistin levels were independently associated with higher risk of MDS controlling for age, gender, BMI and serum levels of leptin, IGF-I and IGFBP-3 (p<0.002). Although total and HMW adiponectin were both significantly inversely associated with MDS when modelled either in quartiles or continuously, HMW did not offer any substantial additional predictive value over total adiponectin (Odds ratio (OR)=0.91 versus 0.93 for a 1 microg/ml change, respectively). IGF-I was positively associated with MDS by bivariate analysis and both IGF-I and IGFBP-3 were higher in advanced MDS and higher risk stages, but were not significantly and independently associated with MDS. CONCLUSION Total and HMW adiponectin may have a protective role in MDS, whereas resistin levels may be decreased via a compensatory mechanism.

In vitro activity of polyunsaturated fatty acids on Pseudomonas aeruginosa: relationship to lipid peroxidation

Based on previous findings that gamma-linolenic acid (GLA) inhibits Escherichia coli growth and provokes the induction of strains resistant to aminoglycosides, 19 Pseudomonas aeruginosa strains were exposed in vitro over time to GLA, to arachidonic acid (AA) and to their combination in the presence or absence of vitamin E. All acids were used at a 300 microg/ml concentration, whereas vitamin E was added as an antioxidant. Lipid peroxidation was evaluated by the thiobarbiturate assay measuring malonodialdehyde (MDA) production. It was found that GLA or AA killed 5-10% of strains at 24 h of growth, whereas when applied in combination their effect involved 100% of strains at 24 h and was limited to 68% of strains in the presence of vitamin E (P< 0.01). MDA production was time-dependent and it was restrained by vitamin E (P < 0.01). Post acid exposure, 27% to 37% of the survived strains became resistant to diverse antimicrobial agents and mainly to ticarcillin, to ceftazidime and to amikacin; no strain developed resistance in the presence of vitamin E. It is concluded that GLA and AA interact bactericidally on P. aeruginosa isolates, inducing the development of strains resistant to beta-lactams and to aminoglycosides; their action might be mediated through their peroxides. Further research is necessary to establish the clinical application of these in vitro findings.

Circulating adiponectin and leptin in relation to myelodysplastic syndrome: a case-control study.

Objective: Adiponectin plays a protective role in several malignancies, including myeloblastic leukemia, whereas leptin may increase the proliferation of progenitor cells and may stimulate leukemic cell growth in vitro. We investigated the role of adiponectin and leptin levels in the etiopathogenesis of myelodysplastic syndromes (MDS), a preleukemic condition with increasing incidence which has recently been associated with obesity. Methods: In a case-control study, 101 cases with incident, histologically confirmed primary MDS and 101 controls matched on gender and age were studied between 2004 and 2007, and blood samples were collected. Results: Higher serum adiponectin levels were associated with lower risk of MDS by bivariate analysis and after adjusting for age, gender, body mass index and serum levels of leptin (p < 0.001). Subjects in the third quartile for leptin levels had a lower risk of MDS than controls, and low leptin concentrations were observed in low-risk MDS patients with normal or good prognostic karyotype after adjusting for age, gender and body mass index. Conclusions: Circulating adiponectin and leptin may play an important role in MDS etiopathogenesis. Future studies are needed to confirm these associations and to explore underlying mechanisms.

Ischemia modified albumin, high-sensitivity c-reactive protein and natriuretic peptide in patients with coronary atherosclerosis.

BACKGROUND Ischemia modified albumin (IMA), is a new biomarker of oxidative processes involved with coronary artery disease (CAD). We determined serum IMA, high-sensitivity C-reactive protein (hsCRP), and natriuretic peptide (NT-proBNP), and evaluated their correlation with severity of coronary atherosclerosis in patients undergoing coronary angiography (CA). Cardiac troponin T (cTnT), CK-MB mass, albumin and Total Antioxidant Status (TAS) were also evaluated. METHODS The study included 114 patients (88 men and 30 women) aged 43-80 years with documented CAD without evidence of acute coronary syndrome undergoing CA and 163 controls (131 men and 32 women) similarly aged. RESULTS IMA, hsCRP and NT-proBNP were higher (p<0.001 and p=0.008 for NT-proBNP) while TAS was lower (p<0.001) in patients than in controls. IMA and TAS were negatively correlated in all subjects (p<0.01). Among patients, there was no correlation between IMA and the number of diseased vessels. For CAD diagnosis the best cut-off point for IMA was 101.5 KU/L with a sensitivity and a specificity of 87.7% and a negative predictive value of 83.3%. IMA was associated with an increased risk for CAD (OR=1.23, 95% CI: 1.16-1.31; p<0.001). CONCLUSIONS IMA determination may provide earlier information of CAD presence before hsCRP or NT-proBNP elevation, contributing to early assessment of overall patient risk.

Leptin, soluble leptin receptor, adiponectin and resistin in relation to OGTT in overweight/obese postmenopausal women

OBJECTIVE In obese postmenopausal women with normal glucose metabolism (NGT) and impaired glucose tolerance (IGT) we assessed serum leptin, adiponectin, resistin, soluble leptin receptor (sOB-R) during oral glucose tolerance test (OGTT) in order to investigate their response to acute changes in glucose and insulin in the abnormal glucose metabolism, as it is early detected by IGT. METHODS Thirty in total, overweight/obese postmenopausal women, were included in the study: 15 with NGT and 15 with IGT as it was diagnosed by OGTT. Serum glucose and insulin levels were measured at 30 min intervals, leptin, sOB-R, adiponectin and resistin at 60 min intervals during the 120 min OGTT. RESULTS In fasting state, leptin, adiponectin, resistin and sOB-R levels did not differ between the two groups. In women with NGT, leptin was positively correlated with BMI, insulin and HOMA, and negatively correlated with QUICKI and with sOB-R; adiponectin was negatively correlated with insulin and HOMA and positively correlated with QUICKI. In women with IGT, resistin was positively correlated with BMI and waist circumference. In both groups, sOB-R was negatively correlated with insulin. During OGTT, in both groups, leptin concentration increased significantly and fasting glucose predicts significantly serum leptin change; there was no change in adiponectin, resistin and sOB-R concentrations. CONCLUSION In overweight/obese postmenopausal women fat distribution does not affect leptin and adiponectin production. Abnormal glucose metabolism is not accompanied by disturbance in adipokines production. Leptin secretion is acutely regulated by glucose levels in insulin presence.

Adipocyte factors, high-sensitive C-reactive protein levels and lipoxidative stress products in overweight postmenopausal women with normal and impaired OGTT

OBJECTIVE In obese postmenopausal women we assessed leptin and adiponectin, high-sensitive C-reactive protein (hsCRP), serum lipids and lipoxidative stress products: oxidized LDL (oxLDL) and malondialdehyde (MDA), in relation to impaired glucose tolerance (IGT). METHODS Thirty-eight overweight/obese postmenopausal women were included in the study. Eighteen with normal glucose metabolism (NGT) and twenty with IGT, as it is diagnosed by OGTT. Serum leptin, adiponectin, hsCRP and MDA were measured at time 0 and 120 min of OGTT while total-cholesterol, LDL, HDL, triglycerides, oxLDL and anti-oxLDL autoantibodies at time 0. Insulin resistance (HOMA)/sensitivity (QUICKI) indexes were estimated. RESULTS In subjects with NGT, hsCRP was positively correlated with fasting leptin and HOMA, while in subjects with IGT negatively with QUICKI. In both groups, hsCRP was positively correlated with fasting insulin, body mass index and waist circumference. Fasting adiponectin was positively associated with HDL in both groups and negatively with triglycerides in subjects with NGT as well as with serum glucose levels at time 120 min of OGTT in subjects with IGT. No association was observed between oxLDL and adipokines. A significant positive association was found between oxLDL and HOMA in subjects with IGT. During OGTT there was a significant increase of leptin and MDA levels in both groups. CONCLUSIONS A relationship exists between obesity, insulin and sub-clinical inflammation. Leptin and lipid peroxidation are linked to hyperglycaemic state while oxLDL might be considered as a predictor of insulin resistance. Adiponectin could exert its antiatherogenic effect through HDL independently of the presence of IGT.

Higher fetuin-A, lower adiponectin and free leptin levels mediate effects of excess body weight on insulin resistance and risk for myelodysplastic syndrome

OBJECTIVE Excess body weight has been implicated in the pathogenesis of myelodysplastic syndrome (MDS). We thus explored the role of serum fetuin-A reflecting ectopic hepatic fat deposition when storage capacity of adipocytes has been exceeded, free leptin reflecting overall fat mass and adiponectin reflecting visceral fat mass, all potential mediators of the effects of obesity on insulin resistance and, consequently, to MDS risk. MATERIALS & METHODS In a hospital-based case-control study, we studied 101 cases with incident, histologically confirmed primary MDS and 101 controls matched on gender, age and date of diagnosis, between 2004 and 2007. Serum fetuin-A, adiponectin, leptin, leptin receptor, free leptin and insulin were determined. RESULTS Higher serum fetuin-A, lower adiponectin and lower free leptin were all individually and independently associated with higher risk of MDS before and after controlling for matching and risk factors, such as age, gender, date of diagnosis, body mass index (BMI), family history of lymphohematopoietic cancer, smoking history and serum insulin. Interestingly, we have shown that these associations were prominent among overweight/obese individuals and persisted after controlling for BMI and serum insulin indicating that their effects are above and beyond insulinemia only. CONCLUSION Elevated serum fetuin-A but lower adiponectin and free leptin are associated with higher risk of MDS particularly among overweight/obese individuals. These findings suggest that the association between excessive weight gain and the risk of MDS could be mediated by fetuin-A, adiponectin and free leptin, which may have potential clinical and preventive implications.

Circulating oxidized LDL levels, current smoking and obesity in postmenopausal women.

OBJECTIVE The aim of the present study was to estimate circulating oxidized low-density lipoprotein (oxLDL) levels in postmenopausal women and evaluate their association with obesity and smoking status. DESIGN AND METHODS The study included 135 postmenopausal women aged 52-75 years. Forty of them were overweight (BMI 32.4+/-6.4) and non-smokers (Group A), 40 non-overweight (BMI 22.6+/-1.8) and smokers (Group B) and 55 non-overweight (BMI 23.5+/-1.4) and non-smokers (Group C). oxLDL and antibodies against them (anti-oxLDL) were measured using ELISA. Serum total cholesterol, LDL, HDL and triglycerides were measured in an automated analyzer. RESULTS Total cholesterol, LDL, HDL and oxLDL serum levels were significantly elevated in Group A as compared to Group B or C, as well as oxLDL in Group B in comparison to Group C (p<0.001). Triglycerides and anti-oxLDL were increased in Group A in comparison to Group C (p=0.043 and 0.023). Total cholesterol, LDL, triglycerides and anti-oxLDL did not differ between Groups B and C, while HDL was decreased in Group B as compared to Group C (p<0.001). A significant positive correlation was found between oxLDL and LDL in Group A (r=0.53, p<0.001) as well as in Group C (r=0.955, p<or=0.001) and a negative one between oxLDL and HDL in Group C (r=-0.933, p<0.001). Regression analysis revealed that obesity was a stronger predictor of LDL oxidation than smoking. CONCLUSIONS Postmenopausal obesity is involved in the process of LDL oxidation and appears to be a stronger predictor of LDL oxidation than smoking. Future studies are needed to confirm these associations.