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tisdag 20 februari 2018

Silmän sarveiskalvon sfingomyeliini ja keramidit

Näkökykyyn tarvitaan  silmän sisäosien  terveyden lisäksi myös pintaosan, sarveikalvon terveys ja kirkkaus, että  valoaistimusket pääsevät läpi kuin maisemat ikkunasta.  Sarveiskalvo on kuin sitä huoneen ikkunaa, ikkunalasia ja  siihen vaikuttavat samat  molekulaariset rakenteet kuin korneaa vastaavissa kerroksissa  stratum  corneum. Näitä tekijöitä ovat mm.  sfingomyeliini ja ceramidit . Sfingomyeliinejä ja normaaleja keramideja muodostuu  palmitiinihappotasosta  rasva-aineenvaihdunnasa  (C16:0) , samasta  keramidilinjasta muodostuu myös glykosfingolipidejä. Sfingomyeliinillä on metaboliset  tiet ja turn over tahtinsa, joka varmastikin on nopeampi kuin cerebrosideillä.  Tässä on uudehko tutkimus näistä  kornean  rakenteista.

https://www.ncbi.nlm.nih.gov/pubmed/25426847

Curr Eye Res. 2015;40(12):1204-10. doi: 10.3109/02713683.2014.990984. Epub 2014 Nov 26.

Description of the sphingolipid content and subspecies in the diabetic cornea.

Abstract
PURPOSE:
Diabetes mellitus (DM) is characterized by high blood sugar levels over a prolonged period. Long term complications include but not limited heart disease, stroke, kidney failure, and ocular damage. An estimated 382 million people are diagnosed with Type 2 DM accounting for 90% of the cases. Common corneal dysfunctions associated with DM result in impaired vision due to decreased wound healing, corneal edema, and altered epithelial basement membrane. Lipids play a fundamental role in tissue metabolism and disease states. We attempt to determine the role of sphingolipids (SPL) in human Type I and Type II diabetic corneas.
MATERIALS AND METHODS:
Cadaver corneas from healthy (non-diabetic/no ocular trauma), Type I (T1DM), and Type II diabetic (T2DM) donors were obtained and processed for lipidomics using LC-MS/MS.
RESULTS:
Our data show significant differences in the SPL composition between control, T1DM and T2DM corneas. Both T1DM and T2DM showed a 10-folddownregulation of sphingomyelin(SM), 5-fold up regulation of Ceramides (Cer) and 2-fold upregulation of monohexosylceramides (MHC). Differences were also seen in total amounts of SPL where Cer was increased by approximately 3 fold in both T1DM and T2DM where SM decreased by 50% in both T1DM and T2DM when compared to healthy controls. No differences were seen in MHC amounts.
CONCLUSIONS:
Overall, our data indicate major differences in SPL distribution in human diabetic corneas. Information on the sphingolipids role in cornea, corneal cell physiology, and diseases are very limited which highlights the importance of these findings.
KEYWORDS:
Cornea; diabetes; lipidomics; sphingolipids

Kommentti: Tässä mainittakoon että  sfingomyeliinin synteesin portilla toimivat  K1 ja B6 vitamiinit ja samoin ainoa tie pois sfingolipidien aineenvaihdunansta  vaatii silläkin portilla K1-vitamiinia ja B6 vitamiinia . 

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