Expression of cytoskeletal proteins during the course of experimental diabetic nephropathy.

AIMS/HYPOTHESIS: Diabetic nephropathy is characterised by structural changes known to be associated in non-diabetic nephropathies with the expression of the cytoskeletal proteins a-smooth muscle actin and vimentin. We aimed to investigate the expression of cytoskeletal proteins in experimental diabetic nephropathy. METHODS: Rats were made diabetic by an injection of streptozotocin (45 mg/kg). Groups of rats (n = 6) and their respective controls (n = 4) were killed at different time intervals. (days 7, 15, 30, 60, 90 and 120). We also studied two groups of diabetic rats treated with a long-acting insulin; the first (n = 8) was treated from the induction of diabetes and the second (n = 8) received insulin from day 15 onward. At each time-point, kidney function, proteinuria and histology were evaluated. Cytoskeletal proteins and collagens III and IV deposition was determined by immunohistochemistry. Changes in the transcription of the cytoskeletal proteins was determined by northern blot analysis. RESULTS: Although normal glomeruli did not express alpha-smooth muscle actin until late in the time course, it was detected in diabetic mesangium from day 7 onward. In the interstitium, it appeared in a perivascular and peritubular distribution. Vimentin was detectable within normal glomerular epithelial cells and increased rapidly (days 7 and 15) in diabetic rats. Vimentin also appeared early within the lining of the peritubular capillaries and damaged diabetic tubules. These changes were associated with a delayed increased transcription of alpha-smooth muscle actin and vimentin. Treatment with insulin (early or late) attenuated and reversed respectively the expression of cytoskeletal proteins and collagens within diabetic kidneys. Close correlations were noted between the number of alpha-smooth muscle actin positive cells within diabetic glomeruli and mesangial expansion (r = 0.46, p < 0.02) as well as interstitial alpha-smooth muscle actin positive cells and interstitial fibrosis (r = 0.51, p < 0.002). CONCLUSION/INTERPRETATION: Changes in the expression of cytoskeletal proteins within the kidneys of diabetic rats suggest a role for alpha-smooth muscle actin and vimentin in the pathogenesis of diabetic kidney disease.

The effects of 2,4-dichlorophenoxyacetic acid on respiration, nitrogen and carbohydrate metabolism of Aspergillus terreus Thom.

The effects of 2,4-D on respiration, carbohydrate and nitrogen metabolism have excited much interest in relation to higher plants (Hansen 1946, Hseuth and Lou 1946, SMITH et al. 1947, and Said and Naguib 1955). But the effects of 2,4-D on dungi have been tackled to a much less extent (Guiscafre-Arrilaga 1948, Bever and Slife 1948, Wei and Ling 1948, and Manil and Strazewska 1950). These investigators studied the effects exerted on fungal growth. Said and Naguib (1962) studied the effect of 2,4-D on the carbohydrate metabolism of Fusarium moniliforme. They showed that both sucrose inversion and absorption were retarded in the presence of 2,4-D. In the present investigation, a trial was carried out in order to elucidate the effect of 2,4-D on growth, nitrogen and carbohydrate metabolism of Aspergillus terreus when grown on two different nitrogen sources, namely sodium nitrate and ammonium phosphate.