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Biomedical subjects

I R Dickson

Publications and source records attributed to I R Dickson.

35 records · Page 2Linked to original sources
PubMed1980

Effects of demineralization in an ethanolic solution of triethylammonium EDTA on solubility of bone matrix components and on ultrastructural preservation.

A solution of triethylammonium EDTA in 80% ethanol was evaluated as a demineralizing reagent for bone in comparison with aqueous solutions of EDTA. Biochemical analysis and acrylamide gel electrophoresis of extracts of finely powdered bovine bone showed that most of the macromolecular components of the organic matrix extractable in aqueous EDTA were retained when the triethylammonium EDTA reagent was used. Ultrastructural examination of chick tibias decalcified with the reagents showed a better preservation of cellular morphology, especially the membranous components, and more uniformly distributed ground substance, though slightly less in quantity, when the aqueous reagent was used. Use of the two reagents appears to be complementary, the alkylammonium reagent being more appropriate for use in studies of the organic matrix of bone, including immunohistochemical studies of bone glycoproteins. The aqueous reagent is more appropriate for use in studies of cellular ultrastructure.

Amino Acids↗
PubMed1980

Comparative histological study of the effects of high calcium diet and vitamin D supplements on epiphyseal plates of vitamin-D-deficient chicks.

A comparative histological and microradiographic study of the tibial epiphyseal plates of chickens raised on: (1) a vitamin-D-deficient diet; (2) a vitamin-D-deficient diet supplemented with cholecalciferol, and (3) a vitamin-D-deficient diet to which extra calcium had been added, has revealed that a high-calcium diet did not normalize the epiphyseal plates completely. However, it restored the normal length and chondrocyte arrangement to the proliferative zone. The degenerative zone became elongated and this seems to be related to the hypophosphataemic condition which has developed as a result of the special diet.

Animals↗
PubMed1979

Effect of vitamin D deficiency on bone formation in the chick.

1. The process of diaphyseal bone formation can be investigated by studying the rate of incorporation of radioactive precursors, administered in vivo into bone fractions of increasing density. 2. In the 4-week-old vitamin D-treated chick most of the osteoid becomes calcified within 12h and almost all within 2 days. The low-density calcified phase that is formed is converted into a higher density form and within 7 days the greater proportion of the calcified tissue is in the higher density form. 3. In the vitamin D-deficient chick of similar age the rate of calcification of osteoid is decreased, as is the rate of conversion into the higher density phase with the resultant accumulation of the lower density calcified form. 4. The higher density phase probably corresponds to hydroxyapatite and the lower density one to the ACP-pase described by Termine & Posner [(1967) Calcif. Tissue Res. 1, 8--23]. 5. The disorder in the process of calcification seems to be unrelated to the alteration in blood Ca2+ and phosphate concentrations, but related to the presence or absence of cholecalciferol.

Animals↗
PubMed1978

A comparative study of the proteoglycan of growth cartilage of normal and rachitic chicks.

1. Proteoglycan was isolated from growth cartilage of normal and rachitic chicks. 2. The proteoglycan from normal cartilage showed differences in chemical composition and physical properties from a comparable fraction isolated from bovine nasal cartilage. 3. The proteoglycan from rachitic-chick cartilage was of smaller size than tis normal counterpart, though of similar average chemical composition. 4. Differences between proteoglycan from normal and rachitic cartilages can be explained in terms of limited proteolytic cleavage.

Animals↗
PubMed1975

The extraction of phosphoproteins from bovine dentin.

The phosphoprotein obtained by the neutral pH tris buffer extraction of acetic acid demineralized bovine dentin has been compared with the phosphoprotein extracted directly during the neutral pH EDTA demineralization process. The phosphoproteins isolated by DEAE-cellulose chromatography from the neutral pH EDTA demineralization extract are not identical to those isolated by the same procedure from the dentin which had been subjected to acid demineralization. The two demineralization procedures yield phosphoproteins different in amino acid content and in presence of 260 nm UV absorbing moiety. Even after sequential acid demineralization, trisbuffer extraction and EDTA extraction, the residual dentin contains phosphoprotein. A peptide fragment containing both collagen and phosphoprotein moieties has been isolated following digestion and cleavage of the insoluble dentin collagen with cyanogen bromide. The acid demineralization process appears to be accompanied by degradation which removes both protein and non-protein components from the phosphoprotein.

Acetates↗
PubMed1975

Evidence for abnormality of bone-matrix proteins in osteogenesis imperfecta.

Immunological and biochemical techniques demonstrated that the non-collagenous proteins of the organic matrix of bone were abnormal in quantity and composition in four children with osteogenesis imperfecta. This represents the main molecular difference found so far between bone in osteogenesis imperfecta and normal bone.

Adolescent↗
PubMed1971

Studies on the interactions between purified bovine caseins and alkaline-earth-metal ions.

1. Alkaline-earth-metal cations at low concentrations form soluble complexes with bovine caseins. The relative order of binding capacities is: Mg(2+)>Ca(2+)>Ba(2+)>Sr(2+). 2. The cations interact with both free ionized carboxyl groups of aspartic acid and glutamic acid and with monoester phosphate groups covalently bound to serine and threonine; at low concentrations of the cations interactions are predominantly with the phosphate groups. 3. The order of binding capacities for purified components of the casein complex is: alpha(s1)-casein>beta-casein>kappa-casein.

Animals↗