Ultrastructure Features and Three-Dimensional Transmission Electron Tomography of Dhub Lizard (Uromastyx Aegyptia) Cornea and Its Adaptation to a Desert Environment.

We report ultrastructural features and transmission electron tomography of the dhub lizard (Uromastyx aegyptia) cornea and its adaptation to hot and dry environments. Six corneas of dhub lizards were fixed in 2.5% glutaraldehyde and processed for electron microscopy and tomography. The ultrathin sections were observed with a JEOL 1400 transmission electron microscope. The cornea of the dhub lizard is very thin (~28-30 µm). The epithelium constitutes ~14% of the cornea, whereas the stroma constitutes 80% of the cornea. The middle stromal lamellae are significantly thicker than anterior and posterior stromal lamellae. Collagen fibril (CF) diameters in the anterior stroma are variable in size (25-75 nm). Proteoglycans (PGs) are very large in the middle and posterior stroma, whereas they are small in the anterior stroma. Three-dimensional electron tomography was carried out to understand the structure and arrangement of the PG and CFs. The presence of large PGs in the posterior and middle stroma might help the animal retain a large amount of water to protect it from dryness. The dhub corneal structure is equipped to adapt to the dry and hot desert environment.

Effect of green tea on kidney tubules of diabetic rats.

It has been documented that green tea (GT) and its catechin components improve renal failure and inhibit the growth of mesangial cells. In the present study we examined the long-term effect of GT extract on streptozotocin (STZ)-induced diabetic nephropathy and on the glycogen accumulation in the kidney tubules. Male Sprague-Dawley rats were randomly assigned to normal control groups (2, 6, 8 and 12 weeks) and five diabetic groups (n 10) of comparable age. A GT diabetic group received 16 % concentration of GT for 12 weeks post-diabetes induction as their sole source of drinking water. GT treatment significantly (P < 0.01) reduced the serum glucose, glycosylated protein, serum creatinine and blood urea N levels by 29.6 (sem 3.7), 22.7 (sem 5.2), 38.9 (sem 10) and 41.7 (sem 1.9) %, respectively, compared with the diabetic group of comparable age. In addition, the GT-treated group showed a significant 44 (sem 10.8) % higher creatinine clearance (Ccr) compared with the untreated diabetic group. Likewise, GT reduced the urea N, creatinine, glucose and protein excretion rates by 30 (sem 7.6), 35.4 (sem 5.3), 34.0 (sem 5.3) and 46.0 (sem 13.0) % compared with the 12 weeks diabetic group. Administration of GT to 12 weeks diabetic rats significantly (P < 0.001) prevented (99.98 (sem 0.27) % less) the accumulation of glycogen in the kidney tubules. These results indicate that in STZ diabetes, kidney function appears to be improved with GT consumption which also prevents glycogen accumulation in the renal tubules, probably by lowering blood levels of glucose. Therefore, GT could be beneficial additional therapy in the management of diabetic nephropathy.