Role of dietary phosphorus in the progression of renal failure

Dietary phosphorus is thought to be a factor that impairs the residual renal function in patients with chronic renal failure. To determine the effect of dietary phosphorus on the prognosis of chronic renal failure, low-phosphorus milk was prepared from normal cow's milk using boehmite, a synthetic phosphate-ion absorbent. Regular diet, normal cow's milk, and low-phosphorus milk were then given to 5/6-nephrectomized rats and the serum levels of inorganic phosphorus, calcium, creatinine, and blood urine nitrogen in the rats in each group were compared. The serum levels of inorganic phosphorus and calcium were not different among the groups, despite a significant difference in phosphorus intakes. On the other hand, serum levels of creatinine (Cr) and blood urine nitrogen (BUN) in the rats fed low-phosphorus milk were significantly lower (Cr, 0.54+/-0.054mg/dl; BUN, 29.2+/-3.90mg/dl) than those in the rats fed a regular diet (Cr, 0.64+/-0.057mg/dl; BUN, 37.4+/-3.55mg/dl) or normal milk (Cr, 0.61+/-0.040mg/dl; BUN, 34.5+/-3.59mg/dl). No beneficial effect of protein restriction was observed when residual renal functions in rats fed a regular diet and those fed normal milk were compared. The results suggest that dietary phosphorus plays a major role in the progression of renal failure.     

SOD mimics: From the tool box of the chemists to cellular studies

Superoxide dismutases (SODs) are metalloproteins that protect cells against oxidative stress by controlling the concentration of superoxide (O₂⁻) through catalysis of its dismutation. The activity of superoxide dismutases can be mimicked by low-molecular-weight complexes having potential therapeutic applications. This review presents recent strategies for designing efficient SOD mimics, from molecular metal complexes to nanomaterials. Studies of these systems in cells reveal that some SOD mimics, designed to react directly with superoxide, may also indirectly enhance the cellular antioxidant arsenal. Finally, a good understanding of the bioactivity requires information on the cell-penetration, speciation, and subcellular location of the SOD mimics: we will describe recent studies and new techniques that open opportunities for characterizing SOD mimics in biological environments.