Selenium biochemistry and its role for human health

Despite its very low level in humans, selenium plays an important and unique role among the (semi)metal trace essential elements because it is the only one for which incorporation into proteins is genetically encoded, as the constitutive part of the 21st amino acid, selenocysteine. Twenty-five selenoproteins have been identified so far in the human proteome. The biological functions of some of them are still unknown, whereas for others there is evidence for a role in antioxidant defence, redox state regulation and a wide variety of specific metabolic pathways. In relation to these functions, the selenoproteins emerged in recent years as possible biomarkers of several diseases such as diabetes and several forms of cancer. Comprehension of the selenium biochemical pathways under normal physiological conditions is therefore an important requisite to elucidate its preventing/therapeutic effect for human diseases. This review summarizes the most recent findings on the biochemistry of active selenium species in humans, and addresses the latest evidence on the link between selenium intake, selenoproteins functionality and beneficial health effects. Primary emphasis is given to the interpretation of biochemical mechanisms rather than epidemiological/observational data. In this context, the review includes the following sections: (1) brief introduction; (2) general nutritional aspects of selenium; (3) global view of selenium metabolic routes; (4) detailed characterization of all human selenoproteins; (5) detailed discussion of the relation between selenoproteins and a variety of human diseases

Experimental results of the effects of Hungarian climatic conditions to German disease-resistant industrial apple varieties

In the recent years, several disease-resistant apple varieties appeared through the modern breeding technologies. These varieties can be grown with low usage of pesticides, which mean not only environment friendly fruit growing, but the production costs are also lower. In Eastern-Hungary — it is one of the main apple growing regions — a new apple growing structure started to form by the investment of the German Wink Ltd. — several resistant apple varieties were brought from Germany. 'Resistant' refers genetic resistance that usually transferred from the genome of wild apple species. But the fruit of these apple species is not only resistant to diseases, but its quality is poorer, too. In Germany the Re-apples are grown only for the processing industry. Due to climatic circumstances in Eastern Hungary, the first experiences showed better parameters during laboratory measurement, the fruits have more beautiful view, shape and inner characters than usual industrial apples. In our paper we discuss the results of sensory (consumer) tests, carried out in Eastern Hungary and in the Budapest-region the data analysis of systematic storing experiments (refraction, flesh firmness, weight loss, etc.) and profile analysis of fresh and stored Re-apples. (In the profile analysis the ProfiSens software [4,5] has been used.

Studies of biochemical parameters characteristic of oxidative damage in different apple cultivars ( Malus domestica Borkh.) during storage

Biochemical parameters, characteristic of oxidative damage (POX and PPO activity, FRAP value and TP content) were used to study the prolonged storage of novel apple cultivars resistant to several apple tree diseases (Re-apples). In period I, results of apples stored from September to November and from September to December were compared. In period II, results of apples stored from September to December and from September to April were compared. In period I, significant increase in the activity of peroxidase and polyphenoloxidase enzymes, slight increase in total phenol content and slight decrease in FRAP values were detected. In period II, the parameter values decreased. No direct correlations were found between the measured biochemical parameters and the keeping of quality during the prolonged storage, therefore additional comparative studies are needed

Effect of foliar application of selenium on its uptake and speciation in carrot

Carrot (Daucus carota) shoots were enriched by selenium using foliar application. Solutions of sodium selenite or sodium selenate at 10 and 100 lg Se ml�1, were sprayed on the carrot leaves and the selenium content and uptake rate of selenium were estimated by ICP–MS analysis. Anion and cation exchange HPLC were tailored to and applied for the separation of selenium species in proteolytic extracts of the biological tissues using detection by ICP–MS or ESI–MS/MS. Foliar application of solutions of selenite or selenate at 100 lg Se ml�1 resulted in a selenium concentration of up to 2 lg Se g�1 (dry mass) in the carrot root whereas the selenium concentration in the controls was below the limit of detection at 0.045 lg Se g�1 (dry mass). Selenate-enriched carrot leaves accumulated as much as 80 lg Se g�1 (dry mass), while the selenite-enriched leaves contained approximately 50 lg Se g�1 (dry mass). The speciation analyses showed that inorganic selenium was present in both roots and leaves. The predominant metabolised organic forms of selenium in the roots were selenomethionine and c-glutamyl-selenomethyl- selenocysteine, regardless of which of the inorganic species were used for foliar application. Only selenomethionine was detected in the carrot leaves. The identity of selenomethionine contained in carrot roots and leaves was successfully confirmed by HPLC–ESI–MS/MS

No Effects of Organic and Conventional Diets on Intake and Absorption of Zinc and Copper in Men – Evidence from Two Cross-over Trials Using Stable Enriched Isotopes

Organic foods have been repeatedly claimed to have a superior nutrient content. However, effects of production method on absorption of nutrients in vivo remains understood. Our aim was to investigate the effects of organic and conventional diets on intake and absorption of zinc and copper in humans. A double-blind, cross-over, intervention trial (3 dietary periods of 12 days, separated with 2-week-long wash-out periods) was performed in 2008 (n=17) and 2009 (n=16) in young men. The diets were based on 9 crops grown in 2 organic and 1 conventional systems in 2 replications over 2 years. Primary outcomes were intake and apparent absorption of zinc and copper. The absorption was determined by fecal excretion of stable enriched isotopes extrinsically added to the entire menu. Within each year, intake and absorption of zinc (overall mean ± SD 12.35 ± 0.47 mg 10MJ-1 and 44.6% ± 12.1, respectively) and copper (overall mean ± SD 2.12 ± 0.28 mg 10MJ-1 and 41.2% ± 13.2, respectively) were not significantly different between the organic and conventional diets. Growing season had no effect on zinc intake and absorption. However, in 2008 copper intake was higher (P=0.01) and absorption lower (P<0.005) compared with 2009 (mean absorption ± SD; 35.3% ± 13.5 in 2008 and 54.0% ± 10.7 in 2009). Zinc and copper were well absorbed from the investigated diets. The consumption of organic diets did not improve apparent absorption of these trace elements compared with the conventional diets

Consumption of organic diets does not affect intake and absorption of zinc and copper in men–evidence from two cross-over trials

Organic foods have been repeatedly claimed to have a superior nutrient content. However, effects of production method on absorption of nutrients in vivo remains understood. Our aim was to investigate the effects of organic and conventional diets on intake and absorption of zinc and copper in humans. A double-blind, cross-over, intervention trial (3 dietary periods of 12 days, separated with 2-week-long wash-out periods) was performed in 2008 (n=17) and 2009 (n=16) in young men. The diets were based on 9 crops grown in 2 organic and 1 conventional systems in 2 replications over 2 years. Primary outcomes were intake and apparent absorption of zinc and copper. The absorption was determined by fecal excretion of stable enriched isotopes extrinsically added to the entire menu. Within each year, intake and absorption of zinc (overall mean ± SD 12.35 ± 0.47 mg 10MJ-1 and 44.6% ± 12.1, respectively) and copper (overall mean ± SD 2.12 ± 0.28 mg 10MJ-1 and 41.2% ± 13.2, respectively) were not significantly different between the organic and conventional diets. Growing season had no effect on zinc intake and absorption. However, in 2008 copper intake was higher (P=0.01) and absorption lower (P<0.005) compared with 2009 (mean absorption ± SD; 35.3% ± 13.5 in 2008 and 54.0% ± 10.7 in 2009). Zinc and copper were well absorbed from the investigated diets. The consumption of organic diets did not improve apparent absorption of these trace elements compared with the conventional diets

In vitro and in vivo characterization of meloxicam nanoparticles designed for nasal administration

The nasal pathway represents a non-invasive route for delivery of drugs to the systemic circulation. Nanonization of poorly soluble drugs offers a possibility to increase dissolution properties, epithelial permeability or even bioavailability. The aim of the present study was to use in vitro methods to screen formulations which were intended for nasal application, and to perform animal experiments for recognizing the differences in plasmakinetics of intranasal- and oral-administered meloxicam nanoparticles. Due to nanonization the solubility of meloxicam elevated up to 1.2 mg/mL, additionally the extent of dissolution also increased, complete dissolution was observed in 15 min. Favorable in vitro diffusion profile of meloxicam nanoparticles was observed and their epithelial permeability through human RPMI 2650 cells was elevated. The pharmacokinetic parameters were significantly increased when meloxicam was administered as nanoparticles to rats either nasally (increase of Cmax 2.7-fold, AUC 1.5-fold) or orally (increase of Cmax 2.4-fold, AUC 2-fold) as compared to physical mixture of the drug and the excipients