Capture assay for specific IgE. An improved quantitative method

A capture assay for the measurement of specific IgE in the serum of allergic patients is described, using monoclonal anti-human IgE (coated to the wells of a microtiter plate) and biotinylated allergens in solution. In a single incubation, IgE is bound to the solid phase through the Fc fragment and biotinylated allergens react with their specific IgE Fab regions, if present. In a second step, streptavidin-HRP conjugate is added to reveal the amount of biotin fixed on the solid phase. Quantitative determinations are obtained by comparison with a standard curve of total IgE incubated with a biotinylated monoclonal anti-IgE, complementary to the one employed as capture antibody. The assay is unaffected by allergen-specific IgG, shows good intra- and interassay reproducibility and is linear over a wide range of specific IgE concentrations. The method could be used with a wide range of different allergens.

[Circannual rhythm of plasma 25-hydroxycholecalciferol in normal man]

Circannual rhythm of serum 25OH-cholecalciferol has been evaluated in 11 normal adult subjects. Blood samples were collected monthly. The pattern of serum levels of the metabolite was biphasic with the lower average values between January and June and maximal mean levels between July and October. Mean values were higher than in North-European countries. The estimated dietary intake of cholecalciferol was in the normal range. Therefore diet does not seem to account for the relatively elevated serum levels of the metabolite. On the contrary sunlight exposure appeared to have marked influence both on mean 250HD levels and on the seasonal rhythm. In spite of seasonal wide variation of serum 250HD levels, blood calcium and phosphate values were stable. The results of serum PTH assay favour the hypothesis that the maintenance of steady blood calcium levels may be due to seasonal variation of parathyroid secretion.

Albright's hereditary osteodystrophy

The authors observed different clinical forms of Albright's hereditary osteodystrophy in 4 members of a family (two sisters, their mother and the maternal grandfather). The sisters were affected by pseudohypoparathyroidism type I, the older manifested the hypocalcemic variety, the younger the normocalcemic variety; the mother and the grandfather presented only with short stature and subcutaneous calcifications. The variety of clinical and biochemical alterations observed in these 3 generations supports evidence that Albright's hereditary osteodystrophy has a broad spectrum and that distinctions between the various forms of pseudohypoparathyroidsim should not be rigidly considered.

25-hydroxycholecalciferol in the treatment of renal osteodystrophy in haemodialysed patients

The effects of 25-OHD3 on renal osteodystrophy have been studied in 6 patients on maintenance haemodialysis. Administration of 25-OHD3, 50 microgram/day, did not improve biochemical data and intestinal absorption of calcium. With a dose of 100 microgram/day in all patients an increase in blood calcium levels eventually reaching hypercalcemic values was observed. In two cases a fall in alkaline phosphatase toward normal values was noted. In the same cases the treatment-induced hyperphosphatemia, uncontrolled by AI(OH)3 supplementation and similarly high iPTH levels were observed. In two cases repeated bone biopsy following 8 months treatment and not show substantial improvement of bone lesions. In one case addition of 1,25-(OH)2D3 to the treatment with 25-OHD3 led to a more rapid improvement in biochemical parameters and iPTH serum levels. Doses of 25-OHD3 capable to correct blood calcium levels and intestinal absorption of calcium, may have minimal benefit on the osteitis fibrosa component of the bone lesion.

[Behavior of serum 25-hydroxycholecalciferol in humans after administration of vitamin D and 25-OHD3]

Serum levels of 25 hydroxycholecalciferol were evaluated following i.m. and p.o. vit. D2 and D3 and p.o. 25OHD3 administration. While no increment in 25OHD3 serum levels were observed after i. m. administration of non-hydroxylated calciferols, a marked increment of the metabolite was found following the oral administration. However the peak values were largely impredictable. Acute and chronic p.o. administration of 25OHD3 determines a rapid and dose-dependent increase of the serum levels of the metabolite. In addition considering that a lower dosage is required of 25OHD3 compared to vit. D, this metabolite is preferable in the therapeutic use.