Mineralni i polifenolni profil zelenog, crnog, biljnih i voćnih filter čajeva i njihov antioksidativni kapacitet

The aim of this doctoral dissertation was estimation of the antioxidant activity, polyphenol and mineral composition of black, green, herbal and fruit bagged teas. Heaving in mind the fact that different polyphenol compounds as antioxidants can react in vivo by various mechanisms, for determination of the total antioxidative activity was used several spectrophotometric tests (DPPH, ABTS, FRAP and RP) and electrochemical method - cyclic voltammetry. The antioxidant capacity of the analyzed samples was estimated using the antioxidant potency composite index (ACI). For identification and quantification of individual polyphenolic compounds, HPLC chromatography was used, and multi-element composition of bagged teas was determined by ICP-OES method. In order to differentiation analyzed bagged teas, methods of multivariate statistical analysis (PCA and CA) were used. In relation to the obtained results, analyzed bagged teas could contribute to the daily dietary requirements

Fractional Calculus Model of Electrical Impedance Applied to Human Skin

Fractional calculus is a mathematical approach dealing with derivatives and integrals of arbitrary and complex orders. Therefore, it adds a new dimension to understand and describe basic nature and behavior of complex systems in an improved way. Here we use the fractional calculus for modeling electrical properties of biological systems. We derived a new class of generalized models for electrical impedance and applied them to human skin by experimental data fitting. The primary model introduces new generalizations of: 1) Weyl fractional derivative operator, 2) Cole equation, and 3) Constant Phase Element (CPE). These generalizations were described by the novel equation which presented parameter (beta) related to remnant memory and corrected four essential parameters (R-0, R-infinity, alpha, tau(alpha)). We further generalized single generalized element by introducing specific partial sum of Maclaurin series determined by parameters (beta(*), gamma,delta ...). We defined individual primary model elements and their serial combination models by the appropriate equations and electrical schemes. Cole equation is a special case of our generalized class of models for beta* = gamma = delta = ... = 0. Previous bioimpedance data analyses of living systems using basic Cole and serial Cole models show significant imprecisions. Our new class of models considerably improves the quality of fitting, evaluated by mean square errors, for bioimpedance data obtained from human skin. Our models with new parameters presented in specific partial sum of Maclaurin series also extend representation, understanding and description of complex systems electrical properties in terms of remnant memory effects

Monolacunary Wells-Dawson Polyoxometalate as a Novel Contrast Agent for Computed Tomography: A Comprehensive Study on In Vivo Toxicity and Biodistribution

Polyoxotungstate nanoclusters have recently emerged as promising contrast agents for computed tomography (CT). In order to evaluate their clinical potential, in this study, we evaluated the in vitro CT imaging properties, potential toxic effects in vivo, and tissue distribution of monolacunary Wells–Dawson polyoxometalate, α2-K10P2W17O61.20H2O (mono-WD POM). Mono-WD POM showed superior X-ray attenuation compared to other tungsten-containing nanoclusters (its parent WD-POM and Keggin POM) and the standard iodine-based contrast agent (iohexol). The calculated X-ray attenuation linear slope for mono-WD POM was significantly higher compared to parent WD-POM, Keggin POM, and iohexol (5.97 ± 0.14 vs. 4.84 ± 0.05, 4.55 ± 0.16, and 4.30 ± 0.09, respectively). Acute oral (maximum-administered dose (MAD) = 960 mg/kg) and intravenous administration (1/10, 1/5, and 1/3 MAD) of mono-WD POM did not induce unexpected changes in rats’ general habits or mortality. Results of blood gas analysis, CO-oximetry status, and the levels of electrolytes, glucose, lactate, creatinine, and BUN demonstrated a dose-dependent tendency 14 days after intravenous administration of mono-WD POM. The most significant differences compared to the control were observed for 1/3 MAD, being approximately seventy times higher than the typically used dose (0.015 mmol W/kg) of tungsten-based contrast agents. The highest tungsten deposition was found in the kidney (1/3 MAD—0.67 ± 0.12; 1/5 MAD—0.59 ± 0.07; 1/10 MAD—0.54 ± 0.05), which corresponded to detected morphological irregularities, electrolyte imbalance, and increased BUN levels

Electrical properties of human skin as aging biomarkers

A non-invasive bioimpedance spectroscopy (BIS) and Cole-Cole impedance model parameters (R-0, R-infinity, tau and alpha) were used to analyze electrical properties of intact and stripped human skin for both gender subjects divided into younger and older age groups. R-0, R-infinity and tau significantly increased while a significantly decreased with age in stripped skin for both genders (p lt 0.031). Using pooled data with respect to age, gender and skin stripping, R-0, R-infinity and t values were shown to increase with age (p lt 0.0034), R-0, tau and alpha were different between genders (p lt 0.024) and R-0, R-infinity and tau decreased with skin stripping (p lt 0.000008). All of four Cole-Cole parameters were age dependent with specific differences observed for genders and intact and stripped skin layers. Therefore, Cole-Cole parameters, obtained by non-invasive BIS measurements, are a new type of age dependent biomarkers

Electrical properties of human skin as aging biomarkers

A non-invasive bioimpedance spectroscopy (BIS) and Cole-Cole impedance model parameters (R-0, R-infinity, tau and alpha) were used to analyze electrical properties of intact and stripped human skin for both gender subjects divided into younger and older age groups. R-0, R-infinity and tau significantly increased while a significantly decreased with age in stripped skin for both genders (p lt 0.031). Using pooled data with respect to age, gender and skin stripping, R-0, R-infinity and t values were shown to increase with age (p lt 0.0034), R-0, tau and alpha were different between genders (p lt 0.024) and R-0, R-infinity and tau decreased with skin stripping (p lt 0.000008). All of four Cole-Cole parameters were age dependent with specific differences observed for genders and intact and stripped skin layers. Therefore, Cole-Cole parameters, obtained by non-invasive BIS measurements, are a new type of age dependent biomarkers

In vivo toxicity evaluation of a polyoxotungstate nanocluster as a promising contrast agent for computed tomography

Abstract In this study, we demonstrate for the first time, that a discrete metal-oxo cluster α-/β-K6P2W18O62 (WD-POM) exhibits superior performance as a computed tomography (CT) contrast agent, in comparison to the standard contrast agent iohexol. A toxicity evaluation of WD-POM was performed according to standard toxicological protocols using Wistar albino rats. The maximum tolerable dose (MTD) of 2000 mg/kg was initially determined after oral WD-POM application. The acute intravenous toxicity of single WD-POM doses (1/3, 1/5, and 1/10 MTD), which are at least fifty times higher than the typically used dose (0.015 mmol W kg−1) of tungsten-based contrast agents, was evaluated for 14 days. The results of arterial blood gas analysis, CO-oximetry status, electrolyte and lactate levels for 1/10 MTD group (80% survival rate) indicated the mixed respiratory and metabolic acidosis. The highest deposition of WD-POM (0.6 ppm tungsten) was found in the kidney, followed by liver (0.15 ppm tungsten), for which the histological analysis revealed morphological irregularities, although the renal function parameters (creatinine and BUN levels) were within the physiological range. This study is the first and important step in evaluating side effects of polyoxometalate nanoclusters, which in recent years have shown a large potential as therapeutics and contrast agents