Joanna Góralska

Effect of supplementation with vitamin E and C on plasma hsCRP level and cobalt–albumin binding score as markers of plasma oxidative stress in obesity

About 50% of patients presenting acute coronary syndrome not displayed classical risk factors, remaining inaccessible for prevention. Plasma hsCRP [1] and cobalt–albumin binding (ABSU) test [2] were recently introduced as more informative cardiovascular risk markers. Ischemia modified albumin (IMA) assessed with ABSU test, appears to be an indicator of oxidative stress, may not be specific for cardiac ischemia. Data about IMA concentrations in noncardiac ischemia are limited. Vitamin E and C, potent antioxidants have several anti-atherogenic effects [3].

Dicarbonyl stress in clinical obesity.

The glyoxalase system in the cytoplasm of cells provides the primary defence against glycation by methylglyoxal catalysing its metabolism to D-lactate. Methylglyoxal is the precursor of the major quantitative advanced glycation endproducts in physiological systems - arginine-derived hydroimidazolones and deoxyguanosine-derived imidazopurinones. Glyoxalase 1 of the glyoxalase system was linked to anthropometric measurements of obesity in human subjects and to body weight in strains of mice. Recent conference reports described increased weight gain on high fat diet-fed mouse with lifelong deficiency of glyoxalase 1 deficiency, compared to wild-type controls, and decreased weight gain in glyoxalase 1-overexpressing transgenic mice, suggesting a functional role of glyoxalase 1 and dicarbonyl stress in obesity. Increased methylglyoxal, dicarbonyl stress, in white adipose tissue and liver may be a mediator of obesity and insulin resistance and thereby a risk factor for development of type 2 diabetes and non-alcoholic fatty liver disease. Increased methylglyoxal formation from glyceroneogenesis on adipose tissue and liver and decreased glyoxalase 1 activity in obesity likely drives dicarbonyl stress in white adipose tissue increasing the dicarbonyl proteome and related dysfunction. The clinical significance will likely emerge from on-going clinical evaluation of inducers of glyoxalase 1 expression in overweight and obese subjects. Increased transcapillary escape rate of albumin and increased total body interstitial fluid volume in obesity likely makes levels of glycation of plasma protein unreliable indicators of glycation status in obesity as there is a shift of albumin dwell time from plasma to interstitial fluid, which decreases overall glycation for a given glycemic exposure.

Effect of caloric restriction with or without n-3 polyunsaturated fatty acids on insulin sensitivity in obese subjects: a randomized placebo controlled trial

Background Caloric restriction and n-3 polyunsaturated fatty acid (PUFA) supplementation protect from some of the metabolic complications. The aim of this study was to assess the influence of a low calorie diet with or without n-3 PUFA supplementation on glucose dependent insulinotropic polypeptide (GIP) output and insulin sensitivity markers in obese subjects. Methods Obese, non-diabetic subjects (BMI 30–40 kg/m2) and aged 25–65 yr. were put on low calorie diet (1200–1500 kcal/day) supplemented with either 1.8 g/day n-3 PUFA (DHA/EPA, 5:1) (n = 24) or placebo capsules (n = 24) for three months in a randomized placebo controlled trial. Insulin resistance markers and GIP levels were analysed from samples obtained at fasting and during an oral glucose tolerance test (OGTT). Results Caloric restriction with n-3 PUFA led to a decrease of insulin resistance index (HOMA-IR) and a significant reduction of insulin output as well as decreased GIP secretion during the OGTT. These effects were not seen with caloric restriction alone. Changes in GIP output were inversely associated with changes in red blood cell EPA content whereas fasting GIP level positively correlated with HOMA-IR index. Blood triglyceride level was lowered by caloric restriction with a greater effect when n-3 PUFA were included and correlated positively with fasting GIP level. Conclusions Three months of caloric restriction with DHA + EPA supplementation exerts beneficial effects on insulin resistance, GIP and triglycerides. General significance Combining caloric restriction and n-3 PUFA improves insulin sensitivity, which may be related to a decrease of GIP levels.

Carboxylated and undercarboxylated osteocalcin in metabolic complications of human obesity and prediabetes.

Carboxylated osteocalcin (Gla‐OC) participates in bone remodeling, whereas the undercarboxylated form (Glu‐OC) takes part in energy metabolism. This study was undertaken to compare the blood levels of Glu‐OC and Gla‐OC in nonobese, healthy obese, and prediabetic volunteers and correlate it with the metabolic markers of insulin resistance and early markers of inflammation.

Relation of the protein glycation, oxidation and nitration to the osteocalcin level in obese subjects

Carboxylated osteocalcin (Gla-OC) contributes to the bone formation, whereas its undercarboxylated form (Glu-OC) takes part in the energy metabolism. In vitro studies had shown that treatment of osteoblast-like cells with advanced glycation end product-modified bovine serum resulted in reduced synthesis of collagen 1 and osteocalcin. The aim of this study was to find association between Gla-OC and markers of protein glycation, oxidation and nitration, as well as pro-inflammatory and antioxidant defense markers in obese subjects. Non-obese [(body mass index (BMI)<30 kg/m; n=34)] and obese subjects (30<BMI <40 kg/m2; n=98), both sexes, aged 25 to 65 years, were included in this study. Urinary glycation, oxidation and nitration free adduct concentrations were determined by stable isotopic dilution analysis liquid chromatography and mass spectrometry, and normalized to creatinine. Obese subjects had lower Gla-OC serum levels when compared to the non-obese controls. Obese subjects had increased serum concentrations of insulin, C reactive protein, interleukin 6, leptin and insulin resistance index (HOMA IR). Urinary early glycation and advanced glycation end product (AGE) free products, Nε-fructosyl-lysine and 3-deoxyglucosone-derived hydroimidazolone, respectively, and oxidative damage marker, N-formylkynurenine free adduct, were increased in the obese compared to the non-obese subjects. Serum Gla-OC was negatively correlated with urinary methylglyoxal-derived AGE, hydroimidazolone MG-H1, and N-formylkynurenine free adducts. The Gla-OC/Glu-OC index negatively correlated with the MG-H1 free adduct, and correlated positively with the antioxidant defense marker - the glutathione peroxidase activity. Our results suggest that increased AGEs and protein oxidative damage markers in the course of obesity may contribute to decreased Gla-OC level and, consequently, future risk of decreased bone formation.

Cannabinoids – a new weapon against cancer?

Cannabis has been cultivated by man since Neolithic times. It was used, among others for fiber and rope production, recreational purposes and as an excellent therapeutic agent. The isolation and characterization of the structure of one of the main active ingredients of cannabis - Δ9 - tetrahydrocannabinol as well the discovery of its cannabinoid binding receptors CB1 and CB2, has been a milestone in the study of the possibilities of the uses of Cannabis sativa and related products in modern medicine. Many scientific studies indicate the potential use of cannabinoids in the fight against cancer. Experiments carried out on cell lines in vitro and on animal models in vivo have shown that phytocannabinoids, endocannabinoids, synthetic cannabinoids and their analogues can lead to inhibition of the growth of many tumor types, exerting cytostatic and cytotoxic neoplastic effect on cells thereby negatively influencing neo-angiogenesis and the ability of cells to metastasize. The main molecular mechanism leading to inhibition of proliferation of cancer cells by cannabinoids is apoptosis. Studies have shown, however, that the process of apoptosis in cells, treated with recannabinoids, is a consequence of induction of endoplasmic reticulum stress and autophagy. On the other hand, in the cellular context and dosage dependence, cannabinoids may enhance the proliferation of tumor cells by suppressing the immune system or by activating mitogenic factors. Leading from this there is a an obvious need to further explore cannabinoid associated molecular pathways making it possible to develop safe therapeutic drug agents for patients in the future.

Bioavailability of antioxidant vitamins. Relation between the modality of intake and plasma markers of oxidative stress

Keywords Antioxidant vitamins Plasma oxidative stress Modality of intakeIntroductionExperimental and epidemiological data suggest that anti-oxidant vitamin supplementation may preventcardiovascular events [1]. Clinical trials have generallyfailed to confirm benefits [2, 3], possibly due to themodality of intake, in relation to food.The aim of the studyThe aim of the study was to assess the relation between themodality of vitamin intake with plasma markers of oxida-tive stress.Patients and methodsForty-four cardiovascular event-free obese men withoutothers CHD risk factors, without symptoms of inflamma-tory disease and the control group of normoweight healthysubjects (n = 18) were included in the study. Combinedsupplementary vitamin E and vitamin C (2 · 100 and2 · 200 mg daily, respectively) was administered to obesesubjects and the control group on an empty stomach (mode‘‘Fasting’’) or during dinner (mode ‘‘Meal’’), for 14 days,after 14 days of washing period in cross-over study. Allsubjects were evaluated using lipoprotein profile, anthro-pometric parameters, body composition (BMI, WHR, % ofadipose tissue) and insulin resistance (HOMA-IR).Parameters of oxidative stress: TBARS, total plasma lipidhydroperoxides (LOOH), LDL oxidative susceptibility, andantioxidant potency parameters: ferric reducing/antioxidantpower test (FRAP), thiol/albumin ratio, vitamin E, C weremeasured. Redox compensation index (RCI) was calcu-lated from formula: RCI = [FRAP/plasma LOOH/cholesterol]/100.ResultsBiomarkers of oxidative damage were higher, parametersof antioxidant defense were lower in obese subjectscompared to control group (Figs. 1, 2). Plasma vitaminlevel increased after supplementation similarly in bothgroups. Vitamin E and C absorption was increased byfood intake (Fig. 3). Plasma antioxidant potency wasincreased and oxidative stress parameters were markedlydiminished by antioxidant supplementation and foodintake (Fig. 4).ConclusionFood intake increases the bioavailability of antioxidantvitamins and improves their free-radical-scavengingactivity.

Influence of fatty acids on mitochondrial metabolism of adipocyte progenitors and endothelial cells

Context: In obesity, the cells are exposed to excessive amounts of nutrients, especially free fatty acids (FFAs) that induce a variety of metabolic changes. Objective: We investigated the effect of FFAs on the mitochondrial function in different cell populations under stress conditions. Methods: Human adipose tissue progenitor cells (SVF) or endothelial cells (HUVECs) were incubated with 30μM of selected saturated or unsaturated FFA for 24 h, at times supplemented with 5ng/mL tumour necrosis factor alpha (TNFα) for the last 4 h. Changes in oxygen respiration rate, mitochondrial membrane potential (mitoMP) and total ATP content were monitored. Results: Saturated palmitic acid demonstrated no effect, while a selection of unsaturated FFAs ameliorated metabolism of the progenitor SVF cells. TNFα either did not affect or nullified some of the favourable FFA-induced effects. Conclusions: The mitoMP was the most sensitive parameter reflecting positive impact of the unsaturated FFA on the adipose SVF cells’ metabolism.