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Ako snežná slepota vzniká?

Napísal Natália Dujničová 03. január 2025

Zima je obdobím radosti a aktívneho odpočinku, avšak zimné športy a pobyt na horách môžu priniesť aj riziká pre náš zrak. Odborníci varujú pred častým, no často podceňovaným problémom – snežnou slepotou, ktorá môže vážne ohroziť zdravie očí.

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Zdroj foto: Freepik

Zimné športy, horská turistika a pohyb na snehu patria medzi obľúbené aktivity počas zimných mesiacov. Okrem radosti z pohybu na čerstvom vzduchu však nesú aj riziká, ktoré si mnohí neuvedomujú. Jedným z nich je snežná slepota, stav, ktorý môže spôsobiť vážne poškodenie zraku a narušiť zážitok z pobytu na horách. Snežná slepota je dočasné poškodenie rohovky a spojovky spôsobené nadmerným vystavením ultrafialovému (UV) žiareniu. Tento fenomén, známy aj ako fotokeratitída, vzniká v extrémnych podmienkach, akými sú vysoké nadmorské výšky, intenzívne slnečné svetlo a odraz lúčov od snehu či ľadu.

Ako snežná slepota vzniká?

Vo vysokých nadmorských výškach sa intenzita UV žiarenia zvyšuje približne o 10 – 12 % na každých 1000 metrov. Navyše, sneh dokáže odraziť až 80 % UV lúčov späť do atmosféry a očí. „Tento proces môže rýchlo poškodiť rohovku, ktorá absorbuje väčšinu UV žiarenia, čím plní úlohu prirodzeného filtra svetla. Pri nadmernom vystavení však dochádza k zápalu, opuchu a podráždeniu,“ vysvetľuje Mgr. Lívia Šidlová, Dis., refrakčná špecialistka z Očnej Optiky MANIA.

Najzraniteľnejší sú športovci a turisti, ktorí trávia dlhý čas na snehu alebo vo vysokých nadmorských výškach, kde sú vystavení silnejšiemu žiareniu. Ohrození sú aj tí, ktorí používajú nekvalitné slnečné okuliare, napríklad s tmavými sklami, no bez UV filtra. Tmavé okuliare spôsobujú rozšírenie zreníc, čím sa do očí dostáva ešte väčšie množstvo škodlivého žiarenia.

UV žiarenie je pritom nebezpečné aj za oblačného počasia. „Hoci mraky tlmia intenzitu viditeľného svetla, UV lúče prenikajú atmosférou takmer nezmenené, čím môže byť riziko poškodenia očí stále vysoké,“ dopĺňa Šidlová.

Príznaky snežnej slepoty

Snežná slepota má oneskorené prejavy, ktoré sa objavujú po 6 – 12 hodinách od vystavenia UV žiareniu. Medzi príznaky patria ostrá, pálivá bolesť očí, začervenanie spojoviek, nadmerné slzenie a pocit piesku v očiach, zvýšená citlivosť na svetlo (fotofóbia), rozmazané alebo oslabené videnie či opuch očných viečok. V závažnejších prípadoch môže dôjsť k dočasnej úplnej strate zraku. Aj keď je tento stav reverzibilný, môže trvať niekoľko dní a výrazne obmedziť schopnosť pohybu a orientácie. „Okrem akútnych problémov môže opakované vystavenie UV žiareniu viesť k trvalým zmenám a poškodeniam očí. Medzi najzávažnejšie patria vznik šedého zákalu, makulárna degenerácia, rakovina kože v okolí očí, trvalé poškodenie rohovky,” konštatuje refrakčná špecialistka.

Prevencia: Ako sa chrániť pred snežnou slepotou? 

Odborníci kladú dôraz na prevenciu, ktorá zahŕňa používanie kvalitných slnečných alebo lyžiarskych okuliarov s 100 % UV ochranou. „Polarizačné šošovky sú ideálne na zníženie oslnenia od snehu, zatiaľ čo fotochromatické sklá sa prispôsobujú intenzite svetla,“ odporúča Šidlová. Okuliare by mali mať kvalitné tesnenie, aby zabránili prieniku svetla zo strán, a byť kompatibilné s lyžiarskou helmou.

„Ľudia s dioptrickými potrebami majú možnosť využívať špeciálne OTG (Over-the-Glasses) okuliare alebo dioptrické vložky, ktoré sa vkladajú priamo do lyžiarskych okuliarov. Dodatočnú ochranu poskytujú klobúky, šiltovky a prilby s UV filtrom, ktoré znižujú celkovú expozíciu žiareniu,” zdôrazňuje odborník na výber športových doplnkov Mgr. Rastislav Magna z Intersport Foltan Group.

Aj vysokohorskí nosiči sú v strehu 

O nebezpečenstve číhajúcom na horách by vedeli rozprávať najmä ľudia, ktorých výstupy sú pre nich obživou. Štefan Bačkor sa vysokohorskému nosičstvu venuje skoro tridsať rokov a za tento čas zistil, aký problém môže slnko napáchať: „V roku 1996 so začal pracovať ako vysokohorský nosič na Téryho chate, samozrejme aj v zime, mal som 21 rokov a slnečné okuliare som proste nenosil - nebol som na to zvyknutý a mal som pocit, že ich ani nepotrebujem. Po prvých 4 zimách v doline, kde som trávil intenzívne 3-4 dni v týždni ako nosič, horolezec a skialpinista, som zistil, že už mám trochu problém so slnkom na snehu, tak som začal používať slnečné okuliare, či už lyžiarske alebo iné. Stretol som sa v horách s ľuďmi, ktorí za jasného slnečného dňa mali na čerstvom snehu problém s pohybom, či už ako pešiaci alebo lyžiari – skialpinisti,“ dodáva Š. Bačkor a tvrdí, že bez slnečných okuliarov z domu nevyjde, „Aktuálne už bez okuliarov nechodím ani v lete do mesta, takže do džungle celoročne používam fotochromatické sklá, ktoré sa prispôsobia momentálnym svetelným podmienkam. Výborné sú aj poolarizačné sklá,“ hovorí.

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Postihla vás snežná slepota? Tu sú prvé kroky

Ak máte podozrenie na snežnú slepotu, vyhľadajte tmavé prostredie, aplikujte chladivé obklady a vyhnite sa treniu očí. Pri pretrvávajúcich ťažkostiach je nutné vyhľadať odbornú pomoc. „Liečba zahŕňa kvapky na zvlhčenie očí alebo antibiotické masti pri riziku infekcie. Zdravie očí je nenahraditeľné, preto ochranu netreba podceňovať,“ dodáva Šidlová. Ochrana očí pred UV žiarením je rovnako dôležitá ako ochrana pokožky pred spálením. Moderné okuliare dnes spájajú štýl s funkčnosťou a umožňujú užívať si zimné aktivity bez rizika poškodenia zraku.

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  • Komentár steroid medications %AM, %20 %326 %2025 %06:%mar napísal steroid medications

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    2008). FS I-I (MSTN-specific inhibitor derived
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    Thus, MD outcomes confirmed all three complexes had been stable all through
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    al., 2022). Studies have shown that PPI supplies a way of
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    Nevertheless, all the interfaces of proteins don't contribute
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    UA can activate AMPK [38], a common regulator of both
    autophagy and GLUT4 expression [39, 40], which may provide the mechanism by which UA exerts its dual effects on glucose uptake and mitochondrial function.
    The exercise test was carried out until the participant was no longer in a place to preserve a cycling cadence above 40 revolutions per minute.
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    Myostatin inhibitors are a category of medicine that work by blocking the
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    Therefore, the aim of this examine was to look at the results of methoxyisoflavone, ecdysterone, and sulfo-polysaccharide (CSP3) supplementation during
    resistance coaching on body composition, markers of catabolism, and coaching variations.
    Methoxyisoflavone is a member of the flavonoids (isoflavones) household which would possibly
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    The two most popular types of methoxyisoflavones available on the market are 5-methyl-7-methoxy-isoflavone (Methoxyiso-flavone) and 7-Isopropoxyisoflavone (Ipriflavone).

    Earlier research confirmed unchanged myostatin mRNA [12] or decreased myostatin protein expression [32] in single-leg immobilization model.
    Nevertheless, we observed elevated plasma myostatin within the
    PLA-SUPP after the 6-wk protocol, including 2 weeks of single-leg immobilization (Fig 5).
    These outcomes are similar to previous studies that reported a constructive impact of FOR ingestion on blood myostatin levels in people [13] and canine [15].

    Moreover, the share change of myostatin focus in plasma or the circulating myostatin degree
    at day 42 showed a reasonable affiliation with the percentage change in CSA measured by ultrasonography, no matter group (Fig 5C and 5D).
    Evans et al. [14] reported a optimistic association between circulating myostatin focus and MPS on Day 21 of remedies
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    the lack of muscle measurement and LM of the immobilized
    leg during the immobilization phase (Fig 2).
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    In addition, ghrelin has been shown to stop muscle atrophy in rats
    by enhancing AKT phosphorylation, suppressing the MSTN pathway, and activating myogenin and
    MyoD (Chen et al., 2015). Ghrelin formulations for parenteral administration are being developed (Garin et al., 2013).
    Nevertheless, administration by injection over extended periods can lead
    to poor patient compliance and remedy failure, and ghrelin is prone to enzymatic breakdown in blood when delivered intravenously (Brimijoin et al., 2016).
    Ghrelin liposomes coated with chitosan are being developed for nose-to-brain administration for the remedy of
    cachexia (Salade et al., 2017).
    For astronauts on board the International Area Station (ISS), even high-volume resistance exercise doesn't absolutely forestall muscle
    atrophy and weakness2,four and would possibly turn out to be infeasible
    if astronaut well being had been compromised.
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    An improved understanding of mechanisms that underlie spaceflight-induced muscle loss is thus
    wanted. Fortetropin (Canine Muscle Method; Myos, Cedar Knolls, New Jersey, USA), a nonthermal-pasteurized, freeze-dried, fertilized egg yolk product, was shown to have an abundance of proangiogenic and host-defense proteins compared to unfertilized egg yolk (10).
    Fortetropin is believed to advertise muscle development via the reduction of serum myostatin through an undefined mechanism,
    yet the measured effect on serum myostatin levels has varied in research (11,12).
    However, a examine in older women and men demonstrated no
    change in serum myostatin over 21 d of Fortetropin administration, regardless of demonstrating an 18% enhance within the fractional synthetic price of muscle protein in comparison to a placebo
    (13).
    Final however not least, EP1LOGUE includes a proprietary vasodilating
    and nitric oxide-boosting formulation of gallate-enhanced oligomers derived from grape seeds and marketed as 10x extra highly effective than the classic
    citrulline. This means better blood flow to the muscular tissues - and thus enhanced delivery of epicatechin and
    urolithin B. In short, if you would like to grow muscles,
    you have to management myostatin and improve follistatin.
    Oxidative stress results from an imbalance between the antioxidant protection system
    and ROS production of reactive oxygen species,
    resulting in neuronal death or neurodegeneration. The Nrf2/Keap1 signalling pathway is
    an important regulatory pathway concerned in antioxidant responses.
    Nuclear issue erythroid 2-related issue 2 (Nrf2) is
    a redox-sensitive transcription issue that induces
    the expression of several antioxidant proteins.
    These antioxidant proteins are recognized to minimize back the mobile injury attributable to oxidative stress7.
    Overexpression of the Nrf2 downstream gene heme oxygenase 1 (HO-1) also enhances anti-fatigue results and responses to oxidative stress8.

    Subsequently, antioxidant remedy focusing on Nrf2 and HO-1 could successfully
    prevent exercise-induced fatigue and learning and reminiscence impairment.

    Research has demonstrated that the insulin/insulin-like development factor 1 (IGF-1)-dependent mammalian target of rapamycin (mTOR) pathway is
    a vital participant within the development or atrophy of human skeletal muscle.

    In CKD, hindering anabolic brokers, such as IGF-1/insulin element could result in diminished Akt-mTOR signaling, which promotes muscle protein degradation [29].
    Additionally, myostatin serves as a big unfavorable modulator of
    muscle volume, which is elevated in individuals with CKD.
    Activin A receptor type IIB (ActRIIB), the cell floor receptor for
    this protein, which is mostly transcripted in human muscle cells, phosphorylates and prompts a number of transcription variables, together with Smad2,3, and Smad2/4 household.

    Smad2/4 complicated is then translocated to the nucleus, directly influencing protein wasting.
    On the other hand, the phosphorylation of Smad2/Smad3 results in a further decrease
    in p-Akt, hence perpetuating the cycle of muscle protein breakdown [30].
    New research have also established an emergent role for microRNAs (miRNAs) in skeletal muscle wasting in CKD sufferers.

    Myostatin inhibition in the case of the grownup mice involves injection of natural or synthetic myostatin inhibitors such as Follistatin. Even more advantageous to some people are the potential medical applications for treating (some) muscle-wasting diseases or circumstances
    where retaining muscle mass is problematic. Despite the dearth of proof, certain firms claim their exercise supplements additionally act as
    myostatin inhibitors. Creatine not solely powers workouts however can indirectly
    have an effect on myostatin expression by bolstering muscle hypertrophy.

    Primarily Based on the outcomes of this examine, we conclude that supplementation of methoxyisoflavone,
    ecdysterone, and/or sulfo-polysaccharides (CSP3) do not have any have an result on on coaching adaptations
    and/or anabolic/catabolic standing in resistance-trained subjects.
    These findings distinction marketed claims that these nutrients promote muscle
    accretion, enhance anabolic status, lower adipose tissue, and/or improve
    coaching variations in resistance-trained athletes. These information are
    representative of a selected training protocol in addition to particular prescribed doses of the experimental dietary supplements, however the doses used symbolize the really helpful quantity present in these varieties of dietary
    supplements. At 0, 4, and 8-weeks, topics donated fasting blood samples
    and accomplished complete muscular energy, muscular endurance, anaerobic capacity,
    and physique composition analysis. In the absence of quantifiable goal
    information, it should be considered that owners’ interpretation of the questions and
    their answers might be altered with time (i.e., a similar stage
    of exercise could lead to a different score).
    Current research have shown that in addition to myostatin, related activins are all
    able to inhibiting myoblast differentiation and inflicting myotube atrophy.
    A humanized antibody directed towards ActRII
    receptors named Bimagrumab (BYM338) has been produced, which has higher capability to bind to ActRIIA and ActRIIB receptors.

    This antibody is in a position to inhibit the exercise of myostatin and activins by decreasing the phosphorylation of Smad2/3 and the following activation of gene expression caused by Smad transcription components.
    The result of these advanced reactions is the discount of adverse regulators of muscle production [181].
    A phase two scientific study was performed on seventy five patients with kind 2
    diabetes in 2021. The results of this examine confirmed that sufferers treated with
    this antibody (injected monthly for up to
    forty eight weeks) compared to the placebo group, decreased fat mass by 20.5% and elevated lean mass by
    3.6%.
    The VS./HTS method is used to screen compound libraries
    quickly and cost-effectively using high-end computational approaches.
    The actions of many recognized natural compounds have but to be decided, similar to those detailed within the Chinese traditional medication and Korean medicinal
    compound databases. Several teams have attempted to determine novel therapeutic candidates
    that target MSTN, but sadly, a large number of identified compounds weren't MSTN particular and had been additionally found to dam activin A and
    TGF-β signaling (Suh and Lee, 2020a). The specific focusing on of MSTN stays a significant analysis
    problem as many TGF-β ligands exhibit considerable structural similarities.

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