![]() ![]() If you is measured at 20/60 vision this simply means that another person can see 5 minutes of arc from being 60 feet a way…but you would have to go upto 20 feet to see the same thing that “miss perfect eyes” can see as far as 60 feet away. 20/20 is simply defined as Perfect vision (being able to separate 1 min of arc when is ‘subtends” 5 minutes of arc) at 20 feet. Snellen decided that the standard distance you should be able to discriminate space of 1 minute of arc is at 6 meters, or at 20 feet. OK! So where does the “20” in 20/20 come from? Once again, Dr. In other words, he felt perfect human vision is when you can distinguish a space pattern separated by 1 minute of arc. Snellen stated that “standard vision” is the ability to recognize one of his block optotypes when it subtends 5 minutes of arc, or more simply stated, when the space pattern is separated by 1 minute of arc. An Arcminute is equal to 1/16 of one degree. When rays of light come together, they form an angle. OK, so what exactly does that mean in simpler terms? Well arcminutes is a unit of measure, like miles used to measure distance, or liters used to measure liquids, an arcminute is a measure of “angle”. ![]() Snellen decided and defined ‘standard vision’ as the ability to see one of his block optotypes when is “subtended 5 minutes of arc”. the height of the letter is 5 times the thickness of the Optotypes’ line. the thickness of the lines equals the thickness of the white spaces in-between the lines of the optotypes. Snellen invented the first Eye Chart back in 1862, using Optotypes looking like block letters with a specific geometry. Why the letter “E”? Well, on an eye chart we call the letters “optotypes”. Then the letters are random and get smaller as each line goes down. The top row has one famous letter…the letter “E”. Note that this figure consolidates findings from multiple different tumor types not all pathways are operant in all cancers.20/20 vision…What Does It Mean? So what’s the first thing you do during the vision part of your eye health examination? “Read the Chart with the Big letter “E” right? The typical Eye chart has 11 rows of capital letters. Excess exogenous iron resulting from hemolysis or provided by iron-containing nanoparticles can trigger a shift of M2-type tumor associated macrophages to a tumoricidal M1 phenotype. Anti-tumorigenic effects are exerted by PD-L1-stimulated CD8+ T cells, which promote ferroptosis by secreting interferon gamma and inhibiting SLC7A11. TAFs express the iron-dependent enzyme lysyl hydroxylase 2 (LH2) an enzyme that enhances matrix stiffness TAFs also secrete IL6, which upregulates hepcidin, degrades ferroportin, and limits iron efflux from tumor cells. Intercellular trafficking: Pro-tumorigenic effects are mediated by tumor-associated macrophages, which provide iron to tumor cells, as well as by tumor-associated fibroblasts (TAFs). Ferroptosis inducers disable endogenous pathways that reduce oxidized lipids, including the peroxidase GPX4 and the cystine/glutamate antiporter SLC7A11. Iron participates in producing the oxidized membrane lipids that mediate ferroptotic cell death. ![]() The major route of iron efflux is ferroportin (FPN), which is degraded by the secreted peptide hepcidin. Iron in ferritin can also be redistributed following binding to NCOA4 and lysosomal degradation (ferritinophagy), or ferritin-bound iron can be effluxed from the cell via a multivesicular body (MVB)/exosome pathway. Ferritin stores excess iron in a non-toxic bioavailable form. The chaperone PCBP1 delivers iron to ferritin and LOX15, among other targets. Iron taken up by these pathways is delivered to a pool of redox-active iron termed the labile iron pool to supply iron to iron-containing proteins. Intracellular trafficking: Plasma membrane proteins involved in iron uptake are heme transporters FLVCR2 and HRG1 lipocalin 2 receptor LCN2R (also called 24p3R), which binds a lipocalin 2-siderophore-iron complex DMT1 (which is also involved in endosomal iron efflux), which transports Fe 2+ CD44, which binds an iron-hyaluronate complex and TFR1, which binds diferric transferrin. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |