The study of the antigenic properties of tissues and organs of animals in ontogenesis
SummaryThe antigenic properties of the tissue of developing crystalline lens of ducks was studied with the aid of anaphylactic reaction with desensitization.Morphogenesis, the rate of growth of crystalline lens and content of ribonucleic acid (RNA) in it were investigated simultaneously. It was demonstrated that during the early stages of embryogenesis (90–130 hours) the antigens are present in the tissue of developing crystalline lens, which are specific only for the definite stage of development (stage-specific antigens). There is formation and intensive growth of the primary fibers of the crystalline lens and increased concentration of the RNA during this period.
Detection of Fœtal and Sickle-cell Hæmoglobins in Human Anæmias
WE have systematically examined a large number (175) of normal and anæmic bloods for the presence of fœtal hæmoglobin (F-Hb)1 by three methods: (a) the position of the tryptophan fine-structure band2, using the moving-plate method of Holiday3, from which the relative proportions of adult (A-Hb)1 and fœtal hæmoglobin can be estimated4 when more than 10 per cent of the latter is present, though smaller proportions cannot be detected; (b) the Rich ‘slope’ method5, using the Unicam SP.500 spectrophotometer, which has the same order of sensitivity; (c) the rate of alkaline denaturation at pH 12.8, which provides a sensitive means of detecting the more alkaline-resistant fœtal hæmoglobin6.
Brushite-collagen composites for bone regeneration.
Brushite-based biomaterials are of special interest in bone regeneration due to their biocompatibility and biodegradability; on the other hand, collagen is a well-known osteoconductive biomaterial. In the present study a new brushite-collagen composite biomaterial is reported. This new biomaterial was prepared by combining citric acid/collagen type I solutions with a brushite cement powder. The obtained biomaterial was a cement paste, with improved handling properties. The effect of collagen on the setting reaction of brushite cement was studied, and was found to speed up the cement setting reaction. The cement paste set into a hard ceramic material within 18.5+/-2.1min and had compressive strength similar to that of spongeous bone (48.9+/-5.9MPa in dry conditions and 12.7+/-1.5MPa in humid conditions). The combination of collagen with citric acid revealed an interesting synergistic effect on the compressive strength of the composite material. Moreover, this new biomaterial had excellent cohesion properties (ninefold better than brushite cement), and high cellular adhesion capacity (threefold higher than brushite cement). The composite biomaterial described in this study combines good handling properties, compressive strength, cohesion and cell adhesion capacity, along with the osteoconductive and biodegradable properties inherent in brushite and in collagen-based biomaterials.