How to use the world's scarce selenium resources efficiently to increase the selenium concentration in food

The world's rare selenium resources need to be managed carefully. Selenium is extracted as a by-product of copper mining and there are no deposits that can be mined for selenium alone. Selenium has unique properties as a semi-conductor, making it of special value to industry, but it is also an essential nutrient for humans and animals and may promote plant growth and quality. Selenium deficiency is regarded as a major health problem for 0.5 to 1 billion people worldwide, while an even larger number may consume less selenium than required for optimal protection against cancer, cardiovascular diseases and severe infectious diseases including HIV disease. Efficient recycling of selenium is difficult. Selenium is added in some commercial fertilizers, but only a small proportion is taken up by plants and much of the remainder is lost for future utilization. Large biofortification programmes with selenium added to commercial fertilizers may therefore be a fortification method that is too wasteful to be applied to large areas of our planet. Direct addition of selenium compounds to food (process fortification) can be undertaken by the food industry. If selenomethionine is added directly to food, however, oxidation due to heat processing needs to be avoided. New ways to biofortify food products are needed, and it is generally observed that there is less wastage if selenium is added late in the production chain rather than early. On these bases we have proposed adding selenium-enriched, sprouted cereal grain during food processing as an efficient way to introduce this nutrient into deficient diets. Selenium is a non-renewable resource. There is now an enormous wastage of selenium associated with large-scale mining and industrial processing. We recommend that this must be changed and that much of the selenium that is extracted should be stockpiled for use as a nutrient by future generations

Different experimental approaches in modelling cataractogenesis: An overview of selenite-induced nuclear cataract in rats

Cataract, the opacification of eye lens, is the leading cause of blindness worldwide. At present, the only remedy is surgical removal of the cataractous lens and substitution with a lens made of synthetic polymers. However, besides significant costs of operation and possible complications, an artificial lens just does not have the overall optical qualities of a normal one. Hence it remains a significant public health problem, and biochemical solutions or pharmacological interventions that will maintain the transparency of the lens are highly required. Naturally, there is a persistent demand for suitable biological models. The ocular lens would appear to be an ideal organ for maintaining culture conditions because of lacking blood vessels and nerves. The lens in vivo obtains its nutrients and eliminates waste products via diffusion with the surrounding fluids. Lens opacification observed in vivo can be mimicked in vitro by addition of the cataractogenic agent sodium selenite (Na2SeO3) to the culture medium. Moreover, since an overdose of sodium selenite induces also cataract in young rats, it became an extremely rapid and convenient model of nuclear cataract in vivo. The main focus of this review will be on selenium (Se) and its salt sodium selenite, their toxicological characteristics and safety data in relevance of modelling cataractogenesis, either under in vivo or in vitro conditions. The studies revealing the mechanisms of lens opacification induced by selenite are highlighted, the representatives from screening for potential anti-cataract agents are listed

Effect of storage on content of theaflavins and thearubigins in oolong teas

Teaflawiny i tearubiginy, należące do grupy barwników flawonoidowych, mają duży wpływ na właściwości smakowe i barwę herbat fermentowanych. Celem pracy było określenie wpływu rodzaju opakowania, czasu, i warunków przechowywania na zawartość teaflawin i tearubigin w herbatach typu oolong. Herbaty przechowywano przez 12 miesięcy. Początkowa, średnia zawartość teaflawin wynosiła 0,30 g/100 g herbaty oolong, a tearubigin – 5,30 g/100 g herbaty. Po 3 miesiącach przechowywania nastąpiło statystycznie istotne (p ≤ 0,05) [-] zmniejszenie zawartości tearubigin (średnio do 4,04 g/100 g herbaty), a po 4 miesiącach zaobserwowano ubytek teaflawin – średnio do poziomu 0,20 g/100 g herbaty. Po 12 miesiącach przechowywania ubytek teaflawin wyniósł 76,66 %, a tearubigin – 59,24 %. Wykazano, że zawartość tych substancji podlegała mniejszym wahaniom w przypadku herbat przechowywanych w oryginalnych opakowaniach papierowych (torebka papierowa z wewnętrzną ochroną i folią na powierzchni) i metalowych. Ze względu na niestabilność barwników flawonoidowych najmniej korzystne były opakowania szklane i papierowe poddane działaniu promieniowania rozproszonego. Stwierdzono, że podczas przechowywania herbat nastąpiła w nich degradacja barwników, a czas i warunki przechowywania determinowały barwę herbaty oolong.Theaflavins and thearubigins, which belong to a group of flavonoid pigments, have a strong impact on the gustatory properties and the colour of fermented teas. The objective of the research study was to determine the effect of packaging type as well as storage time and conditions on the content of theaflavins and thearubigins in oolong teas. The teas were stored for 12 months. The initial mean content of theaflavins was 0.30 g/100 g of oolong tea, and of thearubigins: 5.30 g/100 g of tea. After 3 months of storage, a statistically significant (p ≤ 0.05) decrease in the content of thearubigins occurred (to 4.04 g/100 g of tea on average) and after 4 months, the reported level of the decreased content of theaflavins was 0.20 g/100 g of tea on average. After 12 months of storage, the decreased level of theaflavins was 76.66 % and of thearubigins: 59.24 %. It was proved that the content of those substances fluctuated less in the case of the teas stored in original paper packaging (paper bag with an inner protective layer and a foil on its surface) and in packaging of metal boxes. The glass and paper packaging exposed to stray light were the least beneficial owing to the instability of flavonoid pigments. It was found that during storage of the teas, a degradation of pigments occurred, and the storage time and conditions determined the colour of the oolong tea

Reciprocal changes in the postnatal expression of the sarcolemmal Na+-Ca2+-exchanger and SERCA2 in rat heart

The aim of this study was to examine the relationship between sarcolemmal Na(+)-Ca2+ exchangers and sarcoplasmic reticulum (SR) Ca(2+) -ATPase (SERCA2) expression and the developmental differences in cardiac Ca2+ handling. Postnatal steady-state mRNA and protein levels were analysed in rat ventricular myocardium by Northern and immunoblot analysis, respectively. This was compared to Na+ gradient-induced and SR oxalate-supported Ca2 transport in isolated membranes. Na(+)-Ca2+ exchanger mRNA declined by 75% between day 1 and 30, whereas SR Ca2+ ATPase mRNA levels increased by 97% during this period. The Na(+)-Ca2+ exchanger mRNA/Ca(2+)-ATPase mRNA ratio was found to be inversely related to post-natal age. The changes in mRNA levels were associated with corresponding developmental differences in the Ca2+ transport activities of the respective membrane proteins. In crude membranes, the Na(+)-dependent Ca2+ transport activity (at 75 microM Ca2+) declined gradually (P < 0.01; mean +/- S.E.) from 17.7 +/- 2.4 nmoles Ca2+/g wet tissue/2s at day 1-3 (n = 5) to a value of 4.2 +/- 1.1 at day 40 (n =4). Conversely, SR Ca2+ uptake increased (P < 0.01) 2.6-fold during this period. The inversely related changes in the post-natal expression and function of the Na(+)-Ca2+ exchanger and SR Ca(2+)-ATPase suggest a coordinated control at the pretranslational level of the cellular Ca2+ transport processes mediated by the two membrane proteins