Zora Krivošíková

Effects of Long-Term Cholecalciferol Supplementation on Mineral Metabolism and Calciotropic Hormones in Chronic Kidney Disease

Background: Data on the efficacy and safety of long-term vitamin D supplementation in chronic kidney disease (CKD) are scarce. We assessed the effects of the 12-month vitamin D3 treatment on mineral metabolism and calciotropic hormones in patients with CKD stages 2–4. Methods: Eighty-seven patients (mean age 66 years, men/women 33/54) were randomized to cholecalciferol treatment with either 5,000 or 20,000 IU/week. Serum calcium, phosphate, 25(OH)D3, 1,25(OH)2D3, PTH and urinary mineral concentrations were obtained at baseline and after 4, 8 and 12 months. Results: The median serum mineral concentrations were normal and not changed throughout the study. The number of hypercalciuric patients slightly increased with higher dose, but no sustained rise in calciuria was present. Vitamin D insufficiency/deficiency was revealed in 72 (83%) patients at baseline and 37 (43%) at month 12. The 25(OH)D3 levels increased more with higher dose; a rise in 1,25(OH)2D3 was less impressive. The parathyroid hormone (PTH) concentrations were reduced, but the number of subjects with PTH below the lower limit for CKD stage 3 increased equally with both doses. Conclusions: Vitamin D insufficiency/deficiency in CKD significantly improved after the 12-month cholecalciferol treatment, with higher dose being more effective and equally safe. Further studies of vitamin D3 effects on bone metabolism are warranted.

Advanced glycation end-product levels in subtotally nephrectomized rats: beneficial effects of angiotensin II receptor 1 antagonist losartan.

The angiotensin II receptor 1 antagonist losartan (L) inhibited the advanced glycated end-products (AGEs) induced expression of transforming growth factor β1 in in vitro experiments performed on renal tubuloepithelial cells. To test the pathophysiological importance of these findings, the possible link between serum AGEs levels and angiotensin system was investigated in the model of normotensive subtotally nephrectomized rats(4/6-NX). Concentration of AGEs in serum of placebo administered 4/6-NX rats (n = 7, 1.09±0.09 U/l) increased slightly in comparison with sham-operated healthy controls (CTRL, n = 8, 0.94±0.10 U/l, p<0.02) as measured by competitive ELISA. Treatment of 4/6-NX rats with L over 12 weeks ameliorated the rise in serum AGEs concentration (1.00±0.12 U/l, n = 15 <0.005) almost to the level observed for CTRL. This effect was further corroborated by the observation, that the impaired renal excretion of AGEs in 4/6-NX-placebo rats (0.07±0.02 U/µmol creatinine) was significantly restored by L (0.09±0.02 U/µmol creatinine, <0.009) and resembled that of the CTRL (0.10±0.03 U/µmol creatinine). Administration of L to 4/6-NX rats significantly improved renal function as evaluated by a smaller rise in serum creatinine and urea concentration. In spite of the improvement in renal function, there were no differences in concentrations of transforming growth factor β1 in serum and in urine among the two groups. These effects were independent of blood pressure. Our data give first evidence, that long-term treatment with angiotensin II receptor 1 antagonist may exert salutary effects on AGEs levels in the rat remnant kidney model, probably due to improved renal function.

Total plasma Nε-(carboxymethyl)lysine and sRAGE levels are inversely associated with a number of metabolic syndrome risk factors in non-diabetic young-to-middle-aged medication-free subjects

Abstract Background: Interaction of advanced glycation end products (AGEs) with their specific cell-surface receptor for AGEs (RAGE) induces production of reactive oxygen species, pro-diabetic, pro-inflammatory, and pro-atherogenic responses. The metabolic syndrome (Metsy) imposes a high risk of development of cardiovascular disease and unequivocally predisposes the non-diabetics to type 2 diabetes mellitus. The aim of the study was to investigate the association between circulating soluble RAGE (sRAGE), Nε-(carboxymethyl)lysine (CML) or AGE-associated fluorescence of plasma (AGE-Fl) with the number of manifested Metsy risk factors in young-to-middle-aged medication-free non-diabetic subjects. Methods: Metsy was classified according to NCEP/ATP III criteria; plasma sRAGE and total CML were determined by ELISA methods and AGE-Fl fluorimetrically. Results: From among 437 participants aged 33±11 years, 58% were females. In total 174 subjects were Metsy risk factors-free, 142 presented one, 59 presented two risk factors, and 62 suffered from Metsy. Plasma sRAGE and CML/albumin levels decreased with increasing number of Metsy risk factors (p<0.01, both), while AGE-Fl/albumin levels remained similar. Multivariate analysis selected waist circumference as a main determinant of plasma sRAGE as well as CML/albumin levels. Conclusions: In young-to-middle-aged non-diabetic medication-free subjects plasma total CML/albumin and sRAGE levels decrease prior to the manifestation of Metsy. With regards to RAGE-mediated CML trapping into adipose tissue inducing dysregulation of pro-inflammatory cytokines, adipokines, and the development of obesity-related insulin resistance, and the potential involvement of sRAGE in feedback regulation of the toxic effects of AGE/RAGE-mediated signaling, this early decline might be of clinical impact in development of type 2 diabetes and its complications.

Alterations in the QRS complex in the offspring of patients with metabolic syndrome and diabetes mellitus: early evidence of cardiovascular pathology

OBJECTIVE This study was undertaken to evaluate the nature and onset of changes in the QRS complex in the offspring of patients with diabetes mellitus (DM) and metabolic syndrome (MetS). METHODS AND METHODS A total of 529 subjects, divided into 5 groups, were included in the study: (i) group DM (n = 92), patients with DM; (ii) group MetS (n = 125), patients with MetS; (iii) group O-DM (n = 109), offspring of patients with DM; (iv) group O-MetS (n = 122), offspring of patients with MetS; and (v) group HO (n = 81), offspring of healthy subjects. QRS parameters analyzed included amplitude, maximum QRS spatial vector magnitude, electrical axis (EA), and 3 electrocardiogram (ECG) criteria for left ventricular hypertrophy based on amplitude criteria: Sokolow-Lyon index, Cornell voltage, and Gubner criterion. RESULTS Patients with DM and MetS showed a significant leftward shift of the EA when compared with the control group. A modest but significant leftward shift of EA was also observed in both offspring groups. These EA and maximum QRS spatial vector magnitude changes were reflected in the individual leads of the 12-lead ECG. The prevalence of a positive diagnosis by accepted electrocardiographic criteria (ECG left ventricular hypertrophy) was low. CONCLUSION Patients with DM and MetS displayed significant changes in QRS complex that suggest depolarization sequence deterioration. Similar changes were observed also in the offspring of patients with DM and MetS, which suggests early subclinical cardiovascular damage. These findings have implications for prevention, early diagnosis, and treatment in the offspring of patients with DM and MetS.

Effects of Trigonelline, an Alkaloid Present in Coffee, on Diabetes-Induced Disorders in the Rat Skeletal System.

Diabetes increases bone fracture risk. Trigonelline, an alkaloid with potential antidiabetic activity, is present in considerable amounts in coffee. The aim of the study was to investigate the effects of trigonelline on experimental diabetes-induced disorders in the rat skeletal system. Effects of trigonelline (50 mg/kg p.o. daily for four weeks) were investigated in three-month-old female Wistar rats, which, two weeks before the start of trigonelline administration, received streptozotocin (60 mg/kg i.p.) or streptozotocin after nicotinamide (230 mg/kg i.p.). Serum bone turnover markers, bone mineralization, and mechanical properties were studied. Streptozotocin induced diabetes, with significant worsening of bone mineralization and bone mechanical properties. Streptozotocin after nicotinamide induced slight glycemia increases in first days of experiment only, however worsening of cancellous bone mechanical properties and decreased vertebral bone mineral density (BMD) were demonstrated. Trigonelline decreased bone mineralization and tended to worsen bone mechanical properties in streptozotocin-induced diabetic rats. In nicotinamide/streptozotocin-treated rats, trigonelline significantly increased BMD and tended to improve cancellous bone strength. Trigonelline differentially affected the skeletal system of rats with streptozotocin-induced metabolic disorders, intensifying the osteoporotic changes in streptozotocin-treated rats and favorably affecting bones in the non-hyperglycemic (nicotinamide/streptozotocin-treated) rats. The results indicate that, in certain conditions, trigonelline may damage bone.

Impact of ovariectomy, high fat diet, and lifestyle modifications on oxidative/antioxidative status in the rat liver

Aim To estimate the impact of high fat diet and estrogen deficiency on the oxidative and antioxidative status in the liver of the ovariectomized rats, as well as the ameliorating effect of physical activity or consumption of functional food containing bioactive compounds with antioxidative properties on oxidative damage in the rat liver. Methods The study was conducted from November 2012 to April 2013. Liver oxidative damage was determined by lipid peroxidation levels expressed in terms of thiobarbituric acid reactive substances (TBARS), while liver antioxidative status was determined by catalase (CAT), glutathione peroxidase (GPx), glutathione S-transferase (GST), glutathione reductase (GR) activities, and glutathione (GSH) content. Sixty-four female Wistar rats were divided into eight groups: sham operated and ovariectomized rats that received either standard diet, high fat diet, or high fat diet supplemented with cereal selenized onion biscuits or high fat diet together with introduction of physical exercise of animals. Results High fat diet significantly increased TBARS content in the liver compared to standard diet (P = 0.032, P = 0.030). Furthermore, high fat diet decreased the activities of CAT, GR, and GST, as well as the content of GSH (P < 0.050). GPx activity remained unchanged in all groups. Physical activity and consumption of cereal selenized onion biscuits showed protective effect through increased GR activity in sham operated rats (P = 0.026, P = 0.009), while in ovariectomized group CAT activity was increased (P = 0.018) in rats that received cereal selenized onion biscuits. Conclusion Feeding rats with high fat diet was accompanied by decreased antioxidative enzyme activities and increased lipid peroxidation. Bioactive compounds of cereal selenized onion biscuits showed potential to attenuate the adverse impact of high fat diet on antioxidative status.

Vitamin D Levels Decline with Rising Number of Cardiometabolic Risk Factors in Healthy Adults: Association with Adipokines, Inflammation, Oxidative Stress and Advanced Glycation Markers

Introduction Hypovitaminosis D associates with obesity, insulin resistance, hypertension, and dyslipoproteinemia. We asked whether the presence of multiple cardiometabolic risk factors, and which particular combination, exerts additive negative effects on 25(OH)D3 levels; and whether 25(OH)D3 levels associate with markers of inflammation and oxidative stress. Subjects and Methods In non-diabetic medication-free adults central obesity (waist-to-height ratio > 0.5); elevated blood pressure (systolic BP≥130 mm Hg and/or diastolic BP ≥85 mm Hg); increased atherogenic risk (log(TAG/HDL) ≥ 0.11); and insulin resistance (QUICKI < 0.322) were considered as cardiometabolic risk factors. 25(OH)D3 status was classified as deficiency (25(OH)D3 ≤20 ng/ml); insufficiency (levels between 20-to-30 ng/ml), or as satisfactory (>30 ng/ml). Plasma adipokines, inflammatory and oxidative stress markers, advanced glycation end-products, and their soluble receptor were determined. Results 162 subjects were cardiometabolic risk factors-free, 162 presented increased (i.e. 1 or 2), and 87 high number (i.e. 3 or 4) of cardiometabolic risk factors. Mean 25(OH)D3 decreased with rising number of manifested risk factors (36 ± 14 ng/ml, 33 ± 14 ng/ml, and 31 ± 15 ng/ml, respectively; pANOVA: 0.010), while prevalence of hypovitaminosis D did not differ significantly. Elevated blood pressure and insulin resistance appeared as significant determinants of hypovitaminosis D. Subjects presenting these risk factors concurrently displayed the lowest 25(OH)D3 levels (29 ± 15 ng/ml). Plasma adipokines, inflammatory and oxidative stress markers, advanced glycation end-products, and their soluble receptor generally differed significantly between the groups, but only advanced oxidation protein products and advanced glycation end-products associated fluorescence of plasma showed significant independent association with 25(OH)D3 levels. Conclusion In apparently healthy adults increasing number of cardiometabolic risk factors associates with poorer 25(OH)D3 status, while the association between 25(OH)D3 status and inflammatory or oxidative stress markers remains equivocal.

Association of sVAP-1, sRAGE, and CML with lactation-induced insulin sensitivity in young non-diabetic healthy women

BACKGROUND In comparison with non-lactating women breast-feeding mothers display higher insulin sensitivity. Recent data suggest that advanced glycation end products, soluble receptor for advanced glycation end products (sRAGE) and soluble vascular adhesion protein-1 (sVAP-1) may play a role in insulin resistance even in healthy subjects. AIM We studied whether breast-feeding induced insulin sensitivity associates with changes in concentrations of circulating sVAP-1, sRAGE and N(ε)-(carboxymethyl)lysine (CML) - chemically defined advanced glycation end product and RAGE ligand. METHODS In 74 lactating non-diabetic mothers, 45 weaned non-diabetic mothers and 50 age-matched non-parous women insulin sensitivity was assessed using Quantitative insulin-sensitivity check index (QUICKI). sVAP-1, sRAGE and CML levels were determined. RESULTS Lactating mothers were more insulin sensitive than their weaned and non-parous counterparts. Lactating mothers displayed the highest concentrations of sRAGE, and higher sVAP-1 levels if compared to weaned mothers. Both groups of mothers presented with lower CML levels than the non-parous women. CONCLUSION Lactation-induced insulin sensitivity is associated with higher sVAP-1 and a tendency towards higher sRAGE levels. Lactation-associated rise in sVAP-1 may promote effective glucose utilization in the mother. Lactation-induced insulin sensitivity vanishes shortly after weaning. In young healthy women CML levels are of no clinical relevance to insulin sensitivity.

Effects of high fat diet, ovariectomy, and physical activity on leptin receptor expression in rat brain and white fat tissue.

Aim To evaluate in a rat animal model whether ovariectomy, high fat diet (HFD), and physical activity in the form of running affect leptin receptor (Ob-R) distribution in the brain and white fat tissue compared to sham (Sh) surgery, standard diet (StD), and sedentary conditions. Methods The study included 48 female laboratory Wistar rats (4 weeks old). Following eight weeks of feeding with standard or HFD, rats were subjected to either OVX or Sh surgery. After surgery, all animals continued StD or HFD for the next 10 weeks. During these 10 weeks, ovariectomy and Sh groups were subjected to physical activity or sedentary conditions. Free-floating immunohistochemistry and Western blot methods were carried out to detect Ob-R in the brain and adipose tissue. Results StD-ovariectomy-sedentary group had a greater number of Ob-R positive neurons in lateral hypothalamic nuclei than StD-Sh-sedentary group. There was no difference in Ob-R positive neurons in arcuatus nuclei between all groups. Ob-R distribution in the barrel cortex was higher in HFD group than in StD group. Ob-R presence in perirenal and subcutaneous fat was decreased in StD-ovariectomy group. Conclusion HFD and ovariectomy increased Ob-R distribution in lateral hypothalamic nuclei, but there was no effect on arcuatus nuclei. Our results are first to suggest that HFD, ovariectomy, and physical activity affect Ob-R distribution in the barrel cortex, which might be correlated with the role of Ob-R in election of food in rats.

Possible health risks in subjects with dominant plant food consumption.

ABSTRACT In two groups of apparently healthy non-obese non-smoking women aged 20-30 years – 79 vegetarians (39 lacto-ovo-vegetarians /plant food, dairy products, eggs/, 40 semi-vegetarians /as lacto-ovo-vegetarians with addition of white meat and fish consumption/) and 81 non-vegetarians (control group on traditional mixed diet) were analyzed the dietary questionnaires of food-frequency and measured the blood concentrations of vitamins B9, C, ?-carotene, B12, D and concentrations of iron. Young women in both groups had similar values of body mass index, concentrations of vitamin C, vitamin B9 and ?-carotene. In vegetarian vs. non-vegetarian group was found the significantly increased daily intake of fiber, whole grain products, pulses, seeds and nuts. These finding suggest that both nutritional groups had the similar nutritional regimen from view of fruit and vegetables and different from view of other key vegetarian food commodities. Vitamin B12, vitamin D and long-chain n-3 fatty acids are not contained in plant food. Bioavailability of iron from food can be lower in presence of phytic acid (from whole grain products and pulses) and fiber (pulses, seeds, nuts, whole grains). In group of lacto-ovo-vegetarians (narrow range of animal food consumption) vs. non-vegetarian or semi-vegetarian groups were found the significantly reduced concentrations of vitamin B12, vitamin D and iron with a greater incidence of deficient values (49 % vs. 13 and 15 % for vitamin B12, 67 % vs. 46 and 50 % for vitamin D, 44 % vs. 20 and 30 % for iron). Long-chain n-3 fatty acid intake (eicosapentaenoic and docosahexaenoic) in lacto-ovo-vegetarian group was significantly reduced and very low (no fish consumption) in comparison to non-vegetarians and semi-vegetarians. Intake of these acids in semi-vegetarians vs. non-vegetarians was non-significantly increased. The substrate for long-chain n-3 fatty acid biosynthesis – ?-linolenic acid was significantly more consumed in vegetarian groups (mainly from linseeds). The findings suggest that limited consumption of animal food and dominant consumption of plant food can be connected with possible health risks (higher incidence of deficient values of vitamin B12, vitamin D, iron and long-chain n-3 fatty acids).