hydroxylysine and Nephrotic-Syndrome

Alport's syndrome probably is a molecular disorder of basement membrane composition. Investigation of urine on basement membrane components such as hydroxylysine and its glycosides, glucosylgalactosylhydroxylysine and galactosylhydroxylysine, may be helpful for diagnosis of the disease. Urinary specimens of 33 patients and 12 siblings were investigated, and the results were compared with those of 14 healthy adults and of 29 healthy children. The urine of patients with glomerulopathies, occurring during childhood (IgA nephropathy, benign recurrent hematuria, poststreptococcal glomerulonephritis, Henoch-Schönlein nephropathy, membranoproliferative glomerulonephritis, and nephrotic syndrome due to minimal lesions), was also investigated. No marked differences between normal and diseased subjects could be demonstrated, with respect to excretion of hydroxylysine and its glycosides, in contrast to data reported in the literature.

Topics: Adolescent; Adult; Child; Child, Preschool; Female; Glomerulonephritis; Glomerulonephritis, IGA; Hematuria; Humans; Hydroxylysine; Kidney Diseases; Male; Nephritis, Hereditary; Nephrotic Syndrome

The composition of the glomerular basement membrane (GBM) was studied in three patients with the congenital nephrotic syndrome of the Finnish type (CNF). A decrease was found in the relative amounts of amino acids characteristic of collagen, i.e. 3-hydroxyproline, 4-hydroxyproline, hydroxylysine and glycine. The decrease of hydroxyproline was also apparent in the ratio of 4-hydroxyproline to proline and in direct assays of 4-hydroxyproline in whole glomeruli. The ratio of 3-hydroxyproline to 4-hydroxyproline was decreased by about 40%. Slight increases were found in the amounts of some amino acids. No significant change was found in the glucose content of the GBM whereas the galactose content was slightly decreased. The results suggest a decrease in the relative amount of the collagen component in the GBM of CNF patients, but a decrease in the relative amount of 3-hydroxyproline indicates that other changes also exist.

Topics: Amino Acids; Basement Membrane; Child, Preschool; Collagen; Finland; Galactose; Glucose; Glycine; Humans; Hydroxylysine; Hydroxyproline; Infant; Kidney Glomerulus; Nephrotic Syndrome

Glomerular basement membranes have been isolated from kidneys of three children presenting with a congenital nephrotic syndrome. The histology of renal tissue was characterized by an increase of the mesangial area mainly due to matrix. Immunofluorescent studies showed no positive staining. After isolation, the glomerular basement membranes contained no more cellular contaminants than normal membranes. Isolated abnormal membranes exhibited, as normal preparations, less than 1% DNA, RNA, phospholipids or glycosaminoglycans. Since the protein content of both membrane preparations was comparable, significant contamination by non-proteic material did not seem likely. Although the amino acid and carbohydrate composition of both normal and abnormal membranes was very similar, the folowing statistically significant differences were observed: diseased membranes exhibited an increased number of hydroxylysine, 3- and 4-hydroxyproline residues, and an increased content of glucosyl-galactosyl-hydroxlysine units. The data suggest that, in the congenital nephrotic syndrome, the production of disaccharide-rich glomerular basement membrane subunits is enhanced, which could interfere with the packing of the peptide chains and therefore account for the altered permeability of the membrane observed in this disease.

Topics: Amino Acids; Basement Membrane; Carbohydrates; Epithelial Cells; Epithelium; Glycosides; Humans; Hydroxylysine; Infant; Kidney Glomerulus; Male; Nephrotic Syndrome