Conformational Transitions and Glycation of Serum Albumin in Patients with Minimal-Change Glomerulopathy

BACKGROUND: There has been a lack of study on the structural changes of serum albumin in patients with minimal change disease (MCD). To determine whether glycation and/or conformational transitions of albumin are involved in the pathogenesis of albuminuria, nine patients with MCD were enrolled in a prospective follow-up study for comparison of these parameters in serum albumin during the remission and relapse of nephrotic syndrome. METHODS: Circular dichroism measurements were made with purified albumin. Ellipticities at each wavelength were transformed to mean residue ellipticity. Monosaccharide composition was analyzed by high-pH anion-exchange chromatography with pulsed amperometric detection. RESULTS: There was no difference in the proportions of alpha-helix, beta-conformation, and beta-turn of albumin between the sera of control patients and those with nephrotic syndrome. However, the proportion of the random configuration was slightly higher in the plasma albumin of patients in relapse than in those in remission. The proportion of the random configuration was lower in the albumin of the serum than in the urine of patients with nephrotic syndrome, but there was no difference in the proportions of alpha-helix, beta-conformation, and beta-turn of albumin between their plasma and urine. CONCLUSION: Our results suggest that conformational changes in albumin are involved in albuminuria in patients with MCD.

Peripheral blood lymphocyte subsets in idiopathic nephrotic syndrome of childhood.

Lymphocyte subsets in the peripheral blood were examined in 34 patients with nephrotic syndrome [27 with minimal change nephrotic syndrome (MCNS), 7 with significant lesions] and 10 normal children. The investigations were done at the onset of disease before administering corticosteroids (n = 34), during the subsequent remission (n = 27), and the first relapse (n = 12). The proportions of T cell subsets (CD3, CD4 and CD8) were determined by immuno-alkaline phosphatase staining; interleukin-2 receptor (IL-2 R) positive cells, natural killer (NK) cells and B cells were studied by indirect immunofluorescence. No significant differences were found in the proportion of CD3, CD4, CD8 and IL-2 R positive cells in patients with MCNS as compared to controls. An increased proportion of NK and B cells was not specific to MCNS and was detected even in those with significant renal lesions. Our findings suggest that T lymphocyte subsets in MCNS are similar to those in normal children.

Atrial natriuretic peptide in children with nephrotic syndrome

Plasma levels of atrial natriuretic peptide [ANP] were measured using a specific and sensitive radioimmunoassay in 40 children with nephrotic syndrome [NS]. Nine patients were steroid resistant and the remaining had primary steroid responsive NS. Renal biopsy was performed to four steroid resistant nephrotic patients and revealed membranoproliferative glomerulo nephritis [MPGN] in three patients and lupus nephritis in one patient. Plasma levels of ANP were also measured in 18 healthy children as a control group. High plasma concentrations of ANP were detected in nephrotic patients during active stage of the disease [edema and heavy proteinuria] irrespective to the underlying renal pathology or to the response to steroid therapy. Plasma ANP values in nephrotic patients correlated negatively with serum albumin and with serum creatinine clearance

Platelet serotonergic mechanisms and glomerulonephritis.

Proven cases (28) of glomerulonephritis (GN) were evaluated for clinico-biochemical profile, bleeding time, platelet count, platelet aggregation and platelet serotonergic mechanisms. Inordinate increase in platelet aggregation and altered platelet serotonergic mechanisms (reduced 5-HT, uptake, reduced intraplatelet 5-HT and increased plasma 5-HT) were demonstrated in some histopathological types of GN. The mechanisms and importance of these alterations have been discussed.