Endothelial Protection

Following damage, corneal epithelial cells can regenerate. A thick protective layer of glycoprotein from mucous secretions protects the epithelium from mechanical trauma. Endothelial cells, however, do not have the same potential to regenerate (e.g., mitosis). 

Intraoperative factors as potential sources of injury to corneal endothelial cells are  

During operations, viscoelastic agents act as a sort of physical shield. Many physical properties contribute to endothelial protection  

To provide the corneal endothelium with good protection, viscoelastic agents should ideally have high viscosity and elasticity at rest (zero shear rate). Such viscoelastic substances could protect the corneal endothelium from compression forces (Fig. 52). Additionally, the viscoelastic should have a steep pseudoplasticity curve, i.e., a quick viscosity reduction with increasing movement. Shear forces conducted to the corneal endothelium would, in this way, be minimized (Hammer 8c Burch, 1984). 

As was seen in in-vitro and animal studies, 1% sodium hyaluronic acid, 10 8c 20% chondroitin sulfate and 1% HPMC solutions protected the corneal endothelial cells from potential injury from direct contact of the lOL or instruments with corneal endothelium (Hammer 8c Burch, 1984 Miyauchi 8c Iwata, 1984). There is, however, no viscoelastic capable of shielding the corneal endothelium from sharp instruments, accentuating the importance of creating and maintaining a deep an- 

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Rhetsinine (2), isolated from the hot water extract of Evodia rutae-carpa (family Rutaceae), was found to inhibit aldose reductase with an IC50 value of 24.1 /rM furthermore, the isolate inhibited sorbitol accumulation by 79.3% at 100 This compound could find potential use in the treatment of diabetic complications. Tetramethylpyrazine (3), one of the active components in Qing Huo Yi Hao, displayed strong antioxidant and endothelial protective effects, which can be comparable as Qing Huo Yi Hao this result indicated that some therapeutic potential of Qing Huo Yi Hao for vascular complications of diabetes may be attributed to the presence of tetramethylpyrazine (3). ... 

Chandrasekar B, Nattel S, Tanguay JE Coronary artery endothelial protection after local delivery of 17beta-estradiol during balloon angioplasty in a porcine model a potential new pharmacologic approach to improve endothelial function. J Am Coll Cardiol 2001 38 1 570-1 576. 

Bouchard JF, Lepicier P, Lamontagne D (2003) Contribution of endocannabinoids in the endothelial protection afforded by ischemic preconditioning in the isolated rat heart Life Sci 72 1859-1870... 

Lawson JA, Farhood A, Hopper RD, Bajt ML, Jaeschke H (2000) The hepatic inflammatory response after acetaminophen overdose role of neutrophils. Toxicol Sci 54 509—516 LeCouter J, Moritz DR, Li B, Phillips GL, Liang XH, Gerber HP, Hillan KJ, Ferrara N (2003) Angiogenesis-independent endothelial protection of liver role of VEGFR-1. Science 299 ... 

In addition, Lau et al. [89] demonstrated that boldine treatment causes endothelial protective activity in hypertensive rats through aortic superoxide inhibition and peroxynitrite generation as well as down-regulation of p47phox protein expression in rat s aortas. Lan et al. 

Endothelial protection from shear- and compression forces... 

Low cohesive and good coating viscoelastics (Fig. 65) offer desirable endothelial protection during the actual phacoemulsification procedure (Fig. 66) and from the subsequent irrigation and aspiration maneuver (Fig. 67) without prematurely rinsing out. 

The super-viscous cohesive agents facilitated surgical maneuvers and endothelial protection more than viscous cohesive agents. By combination of different properties, Healon 5 combines advantages of cohesive and dispersive properties. From the rheological standpoint it is the most ideal product for each step of the phacoemulsification procedure compared to Healon and Healon GV. 

If one alleges that the main function of viscoelastics is to protect the endothelium, this would only then describe the above stated definition if the effect were achieved through metabolism. This is not the case even when considering endothelial protection through viscoelastics from the aspect of electrolyte-metabolism, if one considers electrolyte metabolism of endothelial cells to be included in the broader sense of metabolism. 

Brauweiler P. Bimanual irrigation/aspiration. J Cataract Refract Surg 1996 22 1013-1016 Bresciani C, Lebuisson DA, Eveillard M, Grossiord JL, Drupt F, Montefiore G. Dynamic viscosity and corneal endothelial protection with Healonid, Healon GV, Proviso and Viscoat during phacoemulsification. J Fr Ophthalmol 1996 19 39-50... 

Kerr Muir MG, Sherrard ES, Andrews V, Steel ADM. Air, methylcellulose, sodium hyaluronate and the corneal endothelium endothelial protective agents. Eye 1987 1 480-486 Kim JH. Intraocular inflammation of denatured viscoelastic substance in cases of cataract extraction and lens implantation. J Cataract Refract Surg 1987 13 537-542 Kirkby GR, Gregor ZJ. The removal of silicone oil from the anterior chamber in phakic eyes. Arch Ophthalmol 1987 105 1592... 

Ravalico G, Tognetto, Baccara F, Lovisato A. Corneal endothelial protection by different viscoelastics during phacoemulsification. J Cataract Refract Surg 1997 23 433-439 Raymond L, Jacobson B. Isolation and inhibitory cell growth factors in bovine vitrous. Exp Eye Res 1982 34 267-286... 

Calabresi L, Gomaraschi M, Franceschini G. Endothelial protection by high-density lipoproteins from bench to bedside. Arterioscler Thromb Vase Biol 2003 23 1724-1731. 

Ungvari, Z., Bagi, Z., Feher, A., Recchia, F.A., Sotmtag, W.F., Pearson, K., de Cabo, R., and Csiszar, A. 2010. Resveratrol confers endothelial protection via activation of the antioxidant transcription factor Nrf2. AmJPhysiol Heart Circ Physiol. 299 1118-H24. 

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