Microalbuminuria in diabetic children and adolescents. Relationship with puberty and growth hormone.

Urinary albumin excretion (UAE) was determined by radioimmunoassay in two 24 h urine collections from 125 diabetic children and adolescents and from 71 normal children matched for age and sex. Thirteen patients (10.4%) aged greater than 12 years had microalbuminuria, i.e. log transformed UAE levels above the upper normal range (24.5 mg/24 h). UAE values were positively correlated with age, GH secretion, but not with duration of disease, glycosylated hemoglobin, renal size or N-acetyl-beta-glucosaminidase excretion. Diabetic normoalbuminuric children aged 10 years and older had significantly higher UAE than controls and than younger diabetic patients matched for duration of disease. HLA DR3/DR4 heterozygosity frequency was significantly higher (p less than 0.01) in the microalbuminuric group than in the normoalbuminuric. All microalbuminuric subjects (n = 8) with short duration of disease (3.92 +/- 3.43 yr) developed diabetes at puberty. In conclusion, our cross-sectional study suggests: if a number of factors are combined, i.e. HLA DR3/DR4 heterozygosity, onset of disease at puberty and higher GH values, the probability of developing abnormal levels of UAE will increase.

[Separation of N-acetyl-beta-hexosaminidase isoenzymes. Methological note]. / Separazione degli isoenzimi della N-acetil-beta-esosaminidasi. Nota metodologica.

We examined the activity of total N-acetyl-beta-hexosaminidase and of its isoenzyme forms, that represent different stages of the maturation of the lysosomal hydrolase. In both methods the enzyme catalyzes the separation of 4-methylumbelliferone, a fluorescent substance, from 4-methylumelliferyl-2-acetamido-2-deoxy-beta-D-glucopyranoside. We used Leaback's method for the fluorimetric assay of total enzyme, and Ellis's DEAE-cellulose microcolum chromatography for the assay of its components. We obtained a clear separation of each fraction. We will apply these methods in our further studies of children with renal damage, because hexosaminidase seems to be one of the most sensitive markers of tubular damage.

[Correlation between tryptophan, NEFA and albumins in the nephrotic syndrome]. / Studio delle correlazioni fra triptofano, NEFA e albumina nella sindrome nefrosica.

Many connections were considered between bound and free tryptophan and albumins, NEFA and other aminoacids in 18 proofs in ten subjects of paediatric age affected by nephrotic syndrome. A decrease of total tryptophan and a tendency to increase of free tryptophan were showed in our experience. NEFA, at normal concentrations, should not be responsible for this; and this could suggest that the binding sites on albumins for NEFA and tryptophan are different. Besides there is appearance of a positive correlation between albumins and bound tryptophan and a negative correlation between albumins and free tryptophan. These results can suggest that the reduction of the total tryptophan is due to the loss of the fractions bound to albumins, but urinary tryptophan is not increased in our studies. As the albumins get fewer, there is a lost in linked tryptophan and an increase of free tryptophan. A total reduction of other aromatic aminoacids can also explain, through a reduced intestinal absorption, the decrease of the tryptophan in the nephrotic syndrome.

[Urinary guanidinosuccinic acid in uremic children]. / L'acido guanidinosuccinico urinario in soggetti uremici in eta' pediatrica.

Urinary guanidinosuccinic acid (GSA) was measured in pediatric age: six normal subjects, six chronically uremic patients and five with acute renal failure. Urinary GSA was increased in uremic patients as compared to that in normal subjects: our levels was less than in the growth-up people. These differences might be correlated with different protein metabolism in children.