Renal function was monitored in 20, living-related kidney donors before and after uninephrectomy. Urinary protein excretion and retinoid metabolism respectively were studied in 10 and 6 of these donors. The functional adaptation was characterized by an increase in glomerular filtration rate and tubular function, which began in the first two days after uninephrectomy. Changes in tubular function were also demonstrated by significant increases in the urinary excretion of beta 2 microglobulin (beta 2M), retinol binding protein (RBP), kappa and lambda light chains of immunoglobulins. In addition, a protein identical to or homologous to cellular retinoic acid binding protein (CRABP), appeared in the urine after nephrectomy. We did not find CRABP in serum samples either before or after nephrectomy, suggesting that urinary CRABP was synthesized by the remaining kidney. Increases in serum levels of Vitamin A and RBP were also observed in the post-nephrectomy period. These modifications in retinol metabolism suggest that these substances could have a role as renotropic growth factors in compensatory hypertrophy.

1. Protein constituents were determined in eight amyloid deposits from eight patients (five male and three female), 53 +/- 4 years of age, treated by haemodialysis for 9-20 years using only cuprophane membranes and operated for carpal tunnel syndrome. 2. Soluble proteins were removed by solubilization in phosphate-buffered saline after osmotic lysis. The proteins of the insoluble fibrils were characterized by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis and two-dimensional gel electrophoresis, and immunologically identified by Western blotting. 3. In addition to beta 2-microglobulin, alpha 2-macroglobulin was identified in the fibrillar material. The presence of these two proteins in amyloid deposits was confirmed by immunofluorescent microscopic studies. 4. Our data confirm the presence of beta 2-microglobulin in haemodialysis-associated amyloidosis, and also suggest a possible role for alpha 2-microglobulin: it may protect beta 2-microglobulin from proteolytic digestion, leading to its accumulation in intact form and to amyloid fibril formation.

A functional vascular smooth-muscle actin from bovine aorta was purified to homogeneity by an original method and was able to polymerize. Aortic actin is composed of two major isoforms and at least two minor ones. This actin was not phosphorylated by either cyclic AMP-dependent protein kinase or C kinase. The physical properties of aortic actin were found to be very similar to those of skeletal-muscle actin, except for amino acid composition (three tryptophan residues instead of four). The aortic actin and skeletal-muscle actin differ in the extent of activation of the Mg-dependent ATPase of skeletal-muscle myosin.