Swelling studies of camel and bovine corneal stroma

Clinical Ophthalmology, Sep 2010

Swelling studies of camel and bovine corneal stroma Turki Almubrad, Mohammad Faisal Jamal Khan, Saeed AkhtarCornea Research Chair, Department of Optometry, College of Applied Medical Sciences, King Saud University, Saudi ArabiaAbstract: In the present study we investigated the swelling characteristics of fresh camel and bovine cornea in sodium salt solutions. Swelling studies were carried out at 20 minutes, 14 hours, and 46 hours on five fresh camel and 5 five fresh bovine corneas. During the 20-minute hydration of fresh corneal stroma was investigated using sodium chloride (NaCl), sodium bicarbonate (NaHCO3), sodium acetate (CH3COONa), sodium thiocyanate (NaSCN), and sodium floride (NaF) at 2-minute time intervals. During a 46-hour time period, the hydration study was carried out using NaCl (150, 300 mM) and NaF (150 mM) at random intervals. The 14-hour study was carried out to assess the rehydration of corneal stroma after 6 hours of drying. During the 20-minute swelling studies in the first 2 minutes the rate of hydration in both camel and bovine corneas was high but gradually reduced in the 2–20-minute period. The rates and levels of hydration of camel and bovine cornea were not significantly different from each other in all the strengths of solutions. During the 46-hour swelling studies, the initial rate of hydration (0–2 hours) of camel and bovine stroma, in all solutions was significantly higher (Z = 0.056) compared to hydration during later hours (2–46 hours). Camel stromal hydration (high) in 150 mM NaCl was significantly higher compared to bovine stromal hydration in the same solution during the 10–24, and 24–46-hour time periods. Rehydration in camel stroma was significantly lower than bovine in 150 mM NaF. The 20-minute study showed that there was no selective affinity for particular ions in camel or bovine corneal stroma. Initial swelling in both corneal and bovine stroma is faster and more prominant compared to later swelling. The swelling in camel cornea is more prominant compared to bovine corneal stroma. This could be due to higher negatively charged keratin sulfate–proteoglycans in the stroma. Lower rehydration in camel cornea suggests stronger leaching of proteoglycans from stroma in NaF.Keywords: camel, swelling, sodium thiocyanate, sodium bicarbonate, proteoglycans

A PDF file should load here. If you do not see its contents the file may be temporarily unavailable at the journal website or you do not have a PDF plug-in installed and enabled in your browser.

Alternatively, you can download the file locally and open with any standalone PDF reader:

https://www.dovepress.com/getfile.php?fileID=7689

Swelling studies of camel and bovine corneal stroma

Clinical Ophthalmology swelling studies of camel and bovine corneal stroma 0 Cornea r esearch Chair, Department of Optometry, College of Applied Medical s ciences, King s aud University , saudi Arabia In the present study we investigated the swelling characteristics of fresh camel and bovine cornea in sodium salt solutions. Swelling studies were carried out at 20 minutes, 14 hours, and 46 hours on five fresh camel and 5 five fresh bovine corneas. During the 20-minute hydration of fresh corneal stroma was investigated using sodium chloride (NaCl), sodium bicarbonate (NaHCO3), sodium acetate (CH3COONa), sodium thiocyanate (NaSCN), and sodium floride (NaF) at 2-minute time intervals. During a 46-hour time period, the hydration study was carried out using NaCl (150, 300 mM) and NaF (150 mM) at random intervals. The 14-hour study was carried out to assess the rehydration of corneal stroma after 6 hours of drying. During the 20-minute swelling studies in the first 2 minutes the rate of hydration in both camel and bovine corneas was high but gradually reduced in the 2-20-minute period. The rates and levels of hydration of camel and bovine cornea were not significantly different from each other in all the strengths of solutions. During the 46-hour swelling studies, the initial rate of hydration (0-2 hours) of camel and bovine stroma, in all solutions was significantly higher (Z = 0.056) compared to hydration during later hours (2-46 hours). Camel stromal hydration (high) in 150 mM NaCl was significantly higher compared to bovine stromal hydration in the same solution during the 10-24, and 24-46-hour time periods. Rehydration in camel stroma was significantly lower than bovine in 150 mM NaF. The 20-minute study showed that there was no selective affinity for particular ions in camel or bovine corneal stroma. Initial swelling in both corneal and bovine stroma is faster and more prominant compared to later swelling. The swelling in camel cornea is more prominant compared to bovine corneal stroma. This could be due to higher negatively charged keratin sulfate-proteoglycans in the stroma. Lower rehydration in camel cornea suggests stronger leaching of proteoglycans from stroma in NaF. Turki Almubrad; Mohammad Faisal Jamal; Khan saeed Akhtar - The cornea and sclera together form the outermost covering of the eye and withstand both internal and external forces on the eye to maintain the shape of the eyeball and to protect the contents from mechanical injury.1,2Approximately 90% of the cornea consists of stroma which contains collagen fibrils, proteoglycans (PGs) and keratocytes. The collagen fibrils have a uniform diameter and spacing and are organized in tightly packed, parallel-running lamellae. This specific arrangement of collagen fibrils is essential for corneal transparency.3 In birds and primates (including humans) corneal collagen fibrils (CFs) are heterotypic, comprising chiefly type I and type V collagen molecules.4,5 The cornea also contains large amounts of type VI collagen, which forms microfibrillar structures by lateral aggregation.5 PGs are macromolecular glycoconjugates consisting of specialized polysaccharide chains, glycosaminoglycans (GAGs), which are covalently attached to a protein core.6 In the cornea the extracellular matrix contains a class of small interstitial PGs known as collagen-binding small leucine-rich repeat proteoglycans (SLRRPs), which carry two types of GAG side chains. The family members lumican,7 keratocan,8 and mimecan9 carry keratan sulfate chains, whereas decorin,10,11 biglycan,7,12 and versican13 carry chondroitin sulfate/dermatan sulfate chains. It is believed that these small leucine-rich repeat proteoglycans (SLRRPs) maintain the uniform organization of collagen fibrils, which is responsible for transparency of the cornea. 18 Swelling of the cornea is believed to be due to an excess of l-20u water absorbed by the negatively charged proteoglycans, which -J12 results in nonuniform distribution of collagen fibrils. on Unlike other connective tissues, including sclera, the .270 cornea is transparent. It is believed that the endothelium .496 normally acts as a barrier to maintain the ionic composition .yb735 oopfttihmeumstrhoymdaraltmionat.r1,i1x4 Tahneds,wmeollriengi mofpcoorrtnaenatllys,trtoommaaininvtaivion /om is not manifested because of the presence of a balancing .rcsse l.y outward directed bicarbonate ion pump located in the corneal ep on endothelial lining at the posterior surface of the stroma.15–17 .vdoww lsunae is due to increased light scattering, which is thought to be When the stroma swells it loses its transparency.18,19 This /:sw rseo caused by a nonuniform distribution of water and disrup/ p p tth ro tion of the collagen packing.20 Corneal swelling has been from F studied by placing the corneal stroma in distilled water 21–24 edd and bathing solutions with different ionic strengths and lona pH levels.22 dow Previous swelling studies have been carried out on (...truncated)


This is a preview of a remote PDF: https://www.dovepress.com/getfile.php?fileID=7689

Turki Almubrad, Mohammad Faisal Jamal Khan, Saeed Akhtar. Swelling studies of camel and bovine corneal stroma, Clinical Ophthalmology, 2010, pp. 1053-1060, DOI: 10.2147/OPTH.S12576