SELEN - Masaryk University

SELEN - Masaryk University

SELEN MUDr. Michaela Krlkov Biochemick stav LF MU E-mail: [email protected] 1 22 SELEN (Selenium) Se

Z = 34 Ar = 78,96 sk. VI. A [Ar]3d104s24p4 ox. . II, IV, VI objev: 1817 J.J. Berzelius erven nebo ern polokov 3 referenn hodnoty /S 1,3 - 1,8 mol/l 100 - 140 g/l

g/ Evropa - hranin nedostatek (marginal deficiency) 100 g/l (prmr 1 mol/l = 79 g/l) 70 R mrn nedostatek 55 70 g/l (ovlivnn antioxidativn ochrany) vn nedostatek siln deficit 20 55 g/l kritick koncentrace

Se /B 45 55 g/l ( kardiovask. onem.) < 20 g/l (choroby z nedostatku) 1,2 - 4,7 mol/l = 100 - 370 g/l odhad stavu v organizmu: Se /S, U, potravinov ko 4 Stav Se u obyvatel R Evropou se thnou 2 na Se chud pdn psy: ze S (Skandinvie) na J (ecko, Itlie)

z V (Blorusko) na Z (Nmecko, Francie) R le prv v prseku tchto psem Pjem Se rostlinami je negativn ovlivnn vysokou aciditou pdy (kysel det) a vysokm obsahem Fe. Se v rostlinch dostupnost pro ivoichy vetn lovka 5 Metabolizmus Absorpce Transport a distribuce v organizmu Exkrece

6 Absorpce 76 - 100% Se pijatho potravou bez ohledu na stav Se v organizmu duodenum a jejunum ovlivnna pjmem tokoferolu a naopak 7 Transport, distribuce a vznam v organizmu nejprve vazba na albumin, potom zabudovn do selenoprotein (jako Se-Cys) nejastji jako Se- Cys nebo Se-Met (nevykazuje

biologick inky), acidita ne sirnch analog pi pH 7,4 jako Se- nen skladovn v jtrech, proto pi deficitu v potrav rychle kles koncentrace Se /S a rozvj se deficit 8 Selenoproteiny funkn sloueniny Se Glutathion-peroxidzy (GPx) XOOH + 2 GSH XOH + H2O + GSSG peroxid alkohol

ONOO- + 2 GSH NO2 + H2O + GSSG peroxonitrit 4 formy: plazmatick pGPx, cytosolov cGPx, gastrointestinln GiGPx - tetramery, v kadm ze 4 katalytickch mst je 1 Se-Cys, fosfolipidhydroperoxidov phGPx - monomer 9 Selenoproteiny funkn sloueniny Se

Spermln jadern GPx Selenoprotein vzan ve spermln DNA Selenoprotein spermlnho mtch pouzdra Jodtyronin-dejodzy 3 formy, vznik T3 Thioredoxin reduktzy Selenoprotein P ochrana endotelilnch bb. ped peroxonitritem 10 dal selenoproteiny s / bez tkov specifity (nkolik 10)

Exkrece pevn mo, 50 60% Se pijatho potravou, tubulrn exkrece / retence stolic vzrst u stresu a u kompletn parenterln vivy 11 Vznam antioxidan ochrana (GPx; kardiovaskulrn onemocnn, malignity, kognitivn fce) syntza ikosanoid

vliv na imunitn reakce, snen exprese vir, zpomalen vvoje AIDS deaktivace tkch kov (Hg, Cd, Tl, Pb, As) a organickch kancerogennch ltek regulace psoben tyreoidlnch hormon tvorbou a deaktivac T3 (dejodzy) nezbytn pro reprodukci (selenoproteiny s GPx aktivitou aj.) a vvoj 12 Pjem potravou Hlavn zdroje v potrav

paraoechy vnitnosti mosk ryby maso peivo, obilniny lutniny DDD: eny 50 - 55 g /den, mui 55 - 70 g /den, obecn 40 80 g /den,

13 odhad pjmu R 20 40 g /den ! Formy selenu v potrav (ppravcch) Organick Se (selenoMet) aktivn resorpce kanly vysok retence v organizmu antioxidann inky nzk exkrece

Anorganick Se (Na2SeO3) pasivn resorpce difuz nzk retence v organizmu spe prooxidativn inky? vysok exkrece 14 Deficit Rizikov skupiny

dlouhodob parenterln viva postien mukoviscidzou, PKU sportovci a tce pracujc thotn a kojc eny kojenci, dti, pubescenti lid vyho vku 15

Deficit Klinicky svalov ochablost, bolest a slabost depigmentace vlas, ke a neht ten vlasy a ke makrocytza studie Dastych Se u idiopatick skolizy 16

Deficit 1. fze: GPx, zhoren imunitn odezvy; rizika kardiovaskulrnch onemocnn a malignit 2. fze: zmny v hormonlnm metabolizmu, vskyt epidemiologicky zvanch onemocnn, me konit smrt 17 Deficit Keshan disease kardiomyopatie, dochz k pemn nepatogennho coxsackie viru na patogenn kmen; oblast Keshan ve stedn n, N. Zland

Kashin-Beck disease (Kashin a Beckov) osteoartropatie, na myxedmatzn kretenismus - Zair 18 Toxicita Akutn myslet na ni u silnho esnekovho zpachu dechu (vyluovn dimetylselenidu) Chronick bezpen maximln pjem 400 600 g /den nepzniv vliv Se okolo 1 500 g /den selenza (ztrta vlas, nevyvinut a lomiv nehty, kon afekce s

puchky, barevn skvrnky a dolky na zubn sklovin, navnost, zpach dechu) trvale > 2 000 g /den postien GIT, perifernho nervstva > 15 000 g /den 19 Pouit pi stavech nedostatku (v R bn) antioxidan ochrana (kardiovaskulrn choroby, malignity) reprodukce, vvoj (ovlivnn fertility, v gravidit a pi kojen) 20

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