Ljiljana Popovic

Role of Myeloperoxidase in Patients with Chronic Kidney Disease

Chronic kidney disease (CKD) is a worldwide public health problem. Patients with CKD have a number of disorders in the organism, and the presence of oxidative stress and systemic inflammation in these patients is the subject of numerous studies. Chronic inflammation joined with oxidative stress contributes to the development of numerous complications: accelerated atherosclerosis process and cardiovascular disease, emergence of Type 2 diabetes mellitus, development of malnutrition, anaemia, hyperparathyroidism, and so forth, affecting the prognosis and quality of life of patients with CKD. In this review we presented the potential role of the myeloperoxidase enzyme in the production of reactive/chlorinating intermediates and their role in oxidative damage to biomolecules in the body of patients with chronic kidney disease and end-stage renal disease. In addition, we discussed the role of modified lipoprotein particles under the influence of prooxidant MPO intermediates in the development of endothelial changes and cardiovascular complications in renal failure.

Altered Daytime Fluctuation Pattern of Plasminogen Activator Inhibitor 1 in Type 2 Diabetes Patients with Coronary Artery Disease: A Strong Association with Persistently Elevated Plasma Insulin, Increased Insulin Resistance, and Abdominal Obesity

This study was aimed at investigating daily fluctuation of PAI-1 levels in relation to insulin resistance (IR) and daily profile of plasma insulin and glucose levels in 26 type 2 diabetic (T2D) patients with coronary artery disease (CAD) (group A), 10 T2D patients without CAD (group B), 12 nondiabetics with CAD (group C), and 12 healthy controls (group D). The percentage of PAI-1 decrease was lower in group A versus group B (4.4 ± 2.7 versus 35.0 ± 5.4%; P < 0.05) and in C versus D (14.0 ± 5.8 versus 44.7 ± 3.1%; P < 0.001). HOMA-IR was higher in group A versus group B (P < 0.05) and in C versus D (P < 0.01). Simultaneously, AUCs of PAI-1 and insulin were higher in group A versus group B (P < 0.05) and in C versus D (P < 0.01), while AUC of glucose did not differ between groups. In multiple regression analysis waist-to-hip ratio and AUC of insulin were independent determinants of decrease in PAI-1. The altered diurnal fluctuation of PAI-1, especially in T2D with CAD, might be strongly influenced by a prolonged exposure to hyperinsulinemia in the settings of increased IR and abdominal obesity, facilitating altogether an accelerated atherosclerosis.

Influence of Vitamin C Supplementation on Oxidative Stress and Neutrophil Inflammatory Response in Acute and Regular Exercise

Exercise induces a multitude of physiological and biochemical changes in blood affecting its redox status. Tissue damage resulting from exercise induces activation of inflammatory cells followed by the increased activity of myeloperoxidase (MPO) in circulation. Vitamin C readily scavenges free radicals and may thereby prevent oxidative damage of important biological macromolecules. The aim of this study was to examine the effect of vitamin C supplementation on oxidative stress and neutrophil inflammatory response induced by acute and regular exercise. Experiment was conducted on acute exercise group (performing Bruce Treadmill Protocol (BTP)) and regular training group. Markers of lipid peroxidation, malondialdehyde (MDA), MPO activity, and vitamin C status were estimated at rest and after BTP (acute exercise group) and before and after vitamin C supplementation in both groups. Our results showed increased postexercise Asc in serum independently of vitamin supplementation. They also showed that vitamin C can significantly decrease postexercise MDA level in both experimental groups. Increased postexercise MPO activity has been found in both groups and was not affected by vitamin C supplementation. We concluded that vitamin C supplementation can suppress lipid peroxidation process during exercise but cannot affect neutrophil inflammatory response in either exercise group.

PREDICTION OF CARDIOVASCULAR MORTALITY IN FUNCTIONALLY DISABLED ELDERLY – A POSSIBLE NEW SCORE / KARDIOVASKULARNI MORTALITET KOD FUNKCIONALNO ZAVISNIH STARIH OSOBA - MOGUĆI PREDIKTIVNI SKOR

Summary Background: We investigated the traditional and new bio- markers as predictors of cardiovascular mortality in the func- tionally disabled elderly who are living in a community. Methods: This prospective study included 253 participants (78.3% women) aged 65 and over who were monitored for 32 months. Receiver operating curve analysis and the Cox proportional hazard model were used to identify univariate and multivariate predictors of cardiovascular mortality. The Kaplan-Meier survival curve and Log rank test were used for survival analysis. Results: During the study, 43.1% participants died from car- diovascular diseases. Cutoff points of multivariate predictors were used to build a score system. The risk score was positive in patients with three or more of the following predictors: albumin <40 g/L, body mass index <25 kg/m2, total serum bilirubin <10.5 (imol/L, blood urea nitrogen >6.5 mmol/L and high-sensitivity C-reactive protein >2.25 mg/L. The rel- ative risk for cardiovascular mortality for someone with a positive vs. negative score was 3.91 (95% Cl: 2.55-5.98; P< 0.001). There was no change in risk after adjustment for age; sex, traditional cardiovascular risk factors, comorbidities and a number of disabilities. Conclusions: Presence of lo* grade inflammation, malnulri tion and early signs of renal dy sfunction are essential for car- diovascular risk among the functional disabled elderly and may be assessed using the proposed new inflammatory m3lnuhffion-renal involved score (1MRIS). Kratak sadržaj Uvod: Istraživali smo tradicionalne faktore rizika i nove bio- markere kao prediktore za kardiovaskularni mortalitet kod funkcionalno zavisnih starih osoba koje žive u zajednici. Metode: Ova prospektivna studija obuhvatila je 253 učesni- ka starih 65 i vise godina (78,3% žena) koji su praćeni 32 meseca. ROC kriva (engl. receiver operating characteristic curve) i Coxov proporcioni hazardni model korišćeni su za identifikaciju univarijantnih i multivarijantnih prediktora kar- diovaskularnog mortaliteta. Kaplan-Meierova kriva preživlja- vanja i Log rank test korišćeni su za analizu preživljavanja. Rezultati: Tokom studije 43,1% učesnika je umrlo od kar- diovaskularnih bolesti. Na osnovu graničnih (cutoff) skoro- va multivarijantnih prediktora napravljen je prediktivni skor za kardiovaskularni mortalitet. Ovaj skor je bio pozitivan kod učesnika sa tri i vise od sledećih prediktora: albumin <40 g/L, indeks telesne mase <25 kg/m2, ukupni serum- ski bilirubin <10,5 (jmol/L, urea >6,5 mmol/L i visokosen- zitivni C-reaktivni protein >2,25 mg/L. Relativni rizikza kar- diovaskularni mortalitet ukoliko neko ima pozitivan skor bio e 3,91 (95% Cl: 2,55-5,98; P<0,001). Nije bilo promene u riziku nakon prilagođavanja za starost, pol, tradicionalne faktore rizika, komorbiditete i stepen funkcionalne zavisnosti. Zaključak: Prisustvo inflamacije niskog stepena, malnutrici- je i početni znaci bubrežne disfunkcije su esencijalni za procenu kardiovaskularnog rizika kod funkcionalno zavisnih starih osoba i mogu biti procenjeni na osnovu novog pre- diktivnog skora nazvanog IMRIS (engl. inflammatory-mal- nutrition-renal involved skor).

OP3: Oxidized LDL as residual lipid risk marker in type 2 diabetes

Background and aims Previous studies have revealed that the excess of cardiovascular events observed in patients with type 2 diabetes (T2D) and adequate control of low-density lipoprotein cholesterol (LDL) has been explained through the residual lipid risk. The atherogenic potential of diabetes could be associated with the modified proteins as the result of glycation and oxidation. The role of oxidized LDL (oxLDL) as a residual lipid risk marker is still unclarified. The aim of our study was to analyze the levels of oxLDL and their relationship with other standard lipid atherogenic risk factors as well as with insulin resistance (IR) in: T2D patients with coronary artery disease (CAD) (Group A, N=50), T2D patients without CAD (group B, N=45), and nondiabetic patients with CAD (group C, N=50). Material and Methods Patients were aged 40–70 years, matched by gender, duration of diabetes, smoking habit and hypertension. CAD was defined as the presence of any of the following: a) angina, b) myocardial infarction or c) positive angiography. In each patient, oxLDL levels were measured by ELISA methods (Mercodia), glycemic control by the glycated hemoglobin levels (HbA1c, measured by immuno-inhibition). Total cholesterol (TC), HDL and LDL cholesterol and triglycerides (Tg) were determined by enzymatic methods. IR was calculated using homeostatic model assessment insulin resistance (HOMA-IR) index. Results We found the highest levels of oxLDL in group A, being significantly higher than in groups B and C (A: 112.2±22.0, B: 95.9±10.2, C: 83.9±8. A vs B p Conclusion Our results have demonstrated that in patients with T2D and CAD increased oxLDL levels could be good residual lipid risk marker. Atherogenic potential in T2D is associated predominantly with the increased oxLDL, higher IR and impairments in triglycerides metabolism but not with the levels of lipoproteins. Also, the results imply that in T2D patients LDL oxidation is significantly influenced by the impairments in glucose control.

Sequential Analysis of Oxidative Stress Markers and Vitamin C Status in Acute Bacterial Osteomyelitis

In bacterial bone infections, excessively formed oxidants may result in local and systemic oxidative stress. Vitamin C is the major extracellular nonenzymatic antioxidant, also implicated in bone cells metabolism and viability. The physiological functions of vitamin C largely depend on its redox status. We sequentially assessed oxidative stress markers, hydroperoxides and malondialdehyde (MDA), total antioxidant activity (AOA), total vitamin C, ascorbic acid (Asc), and oxidized/reduced vitamin C ratio in 137 patients with acute osteomyelitis (OM). Compared to 52 healthy controls, in OM group baseline serum hydroperoxides, MDA and oxidized/reduced vitamin C ratio were higher whilst Asc and AOA were lower (P < 0.05, resp.). On the other side, total vitamin C levels in patients and controls were similar (P > 0.05), thereby suggesting a relative rather than absolute vitamin C deficiency in OM. During the follow-up, oxidative stress markers, AOA, and oxidizedreduced vitamin C ratio were gradually returned to normal, while there was no apparent change of total vitamin C concentrations. Persistently high values of oxidized/reduced vitamin C ratio and serum MDA were found in subacute OM. In conclusion, acute OM was associated with enhanced systemic oxidative stress and the shift of vitamin C redox status towards oxidized forms.

C-Reactive Protein Predicts Progression of Peripheral Arterial Disease in Patients with Type 2 Diabetes: A 5-Year Follow-Up Study

Summary Background: Previous studies have indicated that high sensitivity C-reactive protein (hs-CRP) is a risk factor for the peripheral arterial disease (PAD) in diabetes. This study aimed to evaluate the possible predictive significance of hs-CRP for the development and progression of PAD in patients with type 2 diabetes (T2D). Methods: The study included 80 patients previously diagnosed with T2D, aged 45–70 years, divided into group A (T2D patients with PAD; n=38) and group B (T2D patients without PAD; n=42). After five years, all the patients were re-examined and divided into subgroups depending on de novo development of PAD or progression of previously diagnosed PAD. Ankle-Brachial Index (ABI) measurement was used for PAD diagnosis and hs-CRP was determined by nephelometry. Results: We found significantly higher hs-CRP levels in group A compared to group B, but only at baseline. Among the patients in group A, those with later progression of PAD (subgroup A1) had the highest levels of hs-CRP at baseline, although not significantly different from those in subgroup A2 (non-progressors). In contrast, hs-CRP level was significantly higher in subgroup B1 (progressors) in comparison to subgroup B2 (non-progressors) at both the first and second exam. Of all the investigated metabolic parameters, hs-CRP was the only independent predictor of PAD progression (OR=0.456, 95% CI=0.267–0.7815, p=0.004). The cut-off point for hs-CRP was 2.5 mg/L (specificity 75% and sensitivity 73.3%) with the relative risk for PAD of 2.93 (95% CI=1.351–6.3629). Conclusions: Our study implies that hs-CRP can be used as a reliable predictor for the progression of PAD in patients with T2D.

mTOR Inhibitor Therapy and Metabolic Consequences: Where Do We Stand?

mTOR (mechanistic target of rapamycin) protein kinase acts as a central integrator of nutrient signaling pathways. Besides the immunosuppressive role after solid organ transplantations or in the treatment of some cancers, another promising role of mTOR inhibitor as an antiaging therapeutic has emerged in the recent years. Acute or intermittent rapamycin treatment has some resemblance to calorie restriction in metabolic effects such as an increased insulin sensitivity. However, the chronic inhibition of mTOR by macrolide rapamycin or other rapalogs has been associated with glucose intolerance and insulin resistance and may even provoke type II diabetes. These metabolic adverse effects limit the use of mTOR inhibitors. Metformin is a widely used drug for the treatment of type 2 diabetes which activates AMP-activated protein kinase (AMPK), acting as calorie restriction mimetic. In addition to the glucose-lowering effect resulting from the decreased hepatic glucose production and increased glucose utilization, metformin induces fatty acid oxidations. Here, we review the recent advances in our understanding of the metabolic consequences regarding glucose metabolism induced by mTOR inhibitors and compare them to the metabolic profile provoked by metformin use. We further suggest metformin use concurrent with rapalogs in order to pharmacologically address the impaired glucose metabolism and prevent the development of new-onset diabetes mellitus after solid organ transplantations induced by the chronic rapalog treatment.

Endothelial dysfunction of coronary arteries in subjects without diabetes: An association with both insulin resistance and impaired insulin secretion response

AIMS This study was aimed to compare insulin sensitivity and secretion response, lipoprotein and plasminogen activator inhibitor 1 (PAI-1) levels between the subjects with and without coronary artery endothelial dysfunction (ED). METHODS ED was detected by intracoronary injection of acetylcholine (ACh) in 47 nondiabetes subjects without stenotic coronary arteries, selected from 316 consecutive patients with coronary angiography performed for suspected coronary artery disease. The subjects were divided into two groups: presence of ACh-induced coronary spasm (group ED+, N = 30) and absence of ACh-induced coronary spasm (group ED-, N = 17). Insulin sensitivity (Si) was evaluated by frequently sampled intravenous glucose tolerance test (FSIGTT) with minimal model analysis and by HOMA-IR, insulin secretion by acute insulin response (AIR) (calculated from the first 8 min of FSIGTT) and by disposition index (DI) (Si × AIR). Lipids and PAI-1 levels were determined enzymatically, and LDL particle size by gradient gel electrophoresis. RESULTS Si was significantly lower (4.22 ± 0.62 vs 6.98 ± 1.47 min-1/mU/l × 104; p < 0.05) while HOMA-IR was significantly higher in ED + group vs ED- group (2.8 ± 0.3 vs 1.7 ± 0.2; p < 0.05). Simultaneously, AIR and DI was significantly lower in ED + vs ED- groups (p < 0.05 and p < 0.01, respectively). Investigated groups did not differ in fasting lipid levels but ED+ group had significantly smaller LDL particles (p < 0.01) and higher PAI-1 levels (p < 0.05). Regression analysis shown that DI was a strong independent predictor of appearance of ED, together with PAI-1 and LDL particle size. CONCLUSIONS Both insulin resistance and impairment in insulin secretion response strongly correlate with coronary ED in subjects without diabetes.

The effects of 3-year statin therapy and the achievement of LDL cholesterol target values in familial hypercholesterolemia patients: An experience from Serbia

BACKGROUND AND AIMS Despite the use of statins, familial hypercholesterolemia (FH) patients often have increased LDL-cholesterol (Ch) and high risk for atherosclerotic cardiovascular disease (ASCVD). This study aimed to analyze the effect of statin therapy on attainment of LDL-Ch treatment targets and appearance of new ASCVD and diabetes in FH patients. METHODS This study is a retrospective analysis of data from medical records of 302 FH patients treated continuously with statins during 3 years. At baseline and once yearly, anthropometric measurements, lipids (total Ch, LDL-Ch, HDL-Ch, triglycerides, apoliporotein A1 and B), fasting plasma glucose, and insulin were determined. RESULTS In FH patients, high intensity statin was prescribed only in 17.9% of cases. LDL-Ch levels were significantly lower after 3 years of statin treatment (3.61 ± 1.19 mmol/l) vs. baseline (4.51 ± 1.69 mmol/l; p < 0.01), but only 6.9% of FH patients reached the recommended ≥50% LDL-Ch reduction and 16.2% attained the LDL-Ch <2.6 mmol/l target. Simultaneously, 9.6% of FH patients developed new ASCVD, with lower HDL-Ch after 3 years of statin treatment than in those who remained free of ASCVD. In addition, we observed new onset diabetes in 6.4% of FH patients who were more obese, older and with higher fasting glucose at baseline than FH patients free of diabetes, regardless of the type of statin. CONCLUSIONS These results imply that only a small proportion of FH patients achieved the recommended LDL-Ch treatment targets, mostly due to the use of low statin dose and infrequent implementation of high-intensity statin treatment, which altogether could not prevent the increase in residual cardiovascular risk.