Biomedical subjects

C J Joyner

Publications and source records attributed to C J Joyner.

7 recordsLinked to original sources

PubMed1992

Phenotypic characterisation of mononuclear and multinucleated cells of giant cell tumour of bone.

Studies were carried out on 3 giant cell tumours of bone (GCTB) to characterise further the cells forming the distinctive mononuclear and multinucleated components. Samples of tumours were grown as explants in vitro and implanted subcutaneously in athymic mice. Cells were characterised in terms of their cell morphology and cytochemical, antigenic and functional phenotype. In culture, giant cells formed a non-proliferative, relatively homogeneous population of cells which expressed features characteristic of the osteoclast phenotype. The mononuclear cell component was heterogeneous and included macrophage-like cells, which persisted for a short time in culture, and fibroblast-like cells which proliferated. In subcutaneous implants, the fibroblast-like cells formed a tissue which included areas of bone formation associated with regions of alkaline phosphatase activity. These observations are consistent with earlier suggestions that the neoplastic component in GCTB consists of a mononuclear stromal cell which elicits a macrophage/osteoclast response.

Adult↗

PubMed1992

Monoclonal antibody BRL 12 reacts with bone keratan sulphate proteoglycan.

Our previous studies suggest that a monoclonal antibody, BRL 12, reacts with a specific product of differentiated cells of the osteoblastic lineage. In the present study, the bone constituent recognized by this antibody has been characterized by gel filtration, ion exchange chromatography, protein blotting and immunolocalization. Our findings show that the antibody reacts with an epitope associated with the core protein of rabbit keratan sulfate proteoglycan (KSPG), a molecule which shares considerable homology with the sialoprotein present in the bone tissue of other mammalian species.

Animals↗

PubMed1991

Adipocytic cells cultured from marrow have osteogenic potential.

Stromal colonies with fibroblastic morphology grown from rabbit marrow cells in culture supplemented with foetal calf serum. In this study the same marrow cells cultured with autologous rabbit plasma and hydrocortisone form colonies of a single lineage that express the adipocytic phenotype. A comparison of the potential for differentiation of cloned cell populations grown from fibroblastic and adipocytic colonies has been made using an in vivo diffusion chamber assay. The adipocytic colonies differentiated and grew to a limited size in medium with rabbit plasma and hydrocortisone, but attempts to isolate them and expand them in this medium failed. When the serum supplement was changed to foetal calf serum at day 10 the cells in the adipocytic colonies acquired a less differentiated morphology, there was a large increase in colony growth and cells were produced in sufficient numbers for the diffusion chamber assay. Thirty one fibroblastic colonies and twenty one adipocytic colonies were isolated either by limiting dilution or ring cloning and then expanded. Of these, eleven fibroblastic and eight adipocytic colonies provided enough cells (2 x 10(5) to 2 x 10(6] for implantation and culture in the chambers. Four of the eleven fibroblastic and three of the eight adipocytic colonies formed an osteogenic tissue in the chambers. It was concluded that cells that have differentiated in an adipocytic direction are able to revert to a more proliferative stage and subsequently to differentiate along the osteogenic pathway. Adipocytic and fibroblastic cells cultured in vitro from marrow have, with osteogenic cells, a common precursor in adult marrow.

Adipose Tissue↗

PubMed1989

Interferon effects on osteoinduction.

Xenografts of human osteosarcoma growing in athymic mice are inhibited in growth rate by human interferon-alpha (IFN-alpha) treatment. In addition, differentiation of trabecular bone occurs external to the osteosarcomatous tissue and this is entirely dependent on IFN treatment. We have used species-specific anticollagens and antivimentin antibodies to determine the species origins of this trabecular bone. By using immunohistochemical procedures, it was found that this bone is host-derived. These results suggest that IFN provoked the production of a bone-inducing agent by the human osteosarcomas.

Animals↗

PubMed1989

Immunohistochemical studies using BRL 12, a monoclonal antibody reacting specifically with osteogenic tissues.

A monoclonal antibody of immunoglobulin class G1 has been produced which reacts with a high molecular weight antigen apparently present exclusively in osteogenic tissues. Immunohistochemical studies have shown that the antigen is present throughout the mineralized matrix and in osteoid. None of the other tissues examined namely liver, intestine, kidney, spleen, thymus, heart, lung, skin, cartilage and skeletal muscle showed evidence of specific antibody binding. Immunohistochemical staining was also demonstrated in tissues developing from rabbit marrow cultured in vitro and in diffusion chambers in vivo. Temporal studies of antigen expression in the chambers indicated that the antigen occurs at sites of bone formation after the appearance of alkaline phosphatase but before the formation of a mineralized matrix. The results of these studies suggest that the monoclonal antibody recognises a product of differentiated osteoblasts. This antibody may therefore prove useful in studies of osteogenic differentiation.

Animals↗

PubMed1987

The effect of age on egg production in the domestic hen.

The effect of age on egg production was investigated in the domestic fowl. The rate of egg production was reduced with increasing age and the incidence of thin-shelled and cracked eggs was markedly increased. Older hens which remained in lay produced fewer but larger eggs than the younger birds. The ovaries of these two groups of hens were of similar appearance but the largest preovulatory follicle and the oviduct were significantly heavier in the older birds. No differences in the circulating levels of progesterone or estradiol were apparent between the young and old birds but the activity of the renal 25-hydroxycholecalciferol 1 alpha-hydroxylase was found to be significantly reduced with age. Circulating levels of total and ionized calcium were very similar in the young and old laying birds, plasma ionized calcium levels being markedly depressed during egg shell calcification in both groups. The decreased rate of ovulation in the older birds and the increase with age in the size of the follicles ovulated is thought to be associated with a reduced rate of recruitment of follicles for rapid growth followed by a prolonged period of follicular growth and development. The poor calcification of egg shell in old birds would appear to be due to some dysfunction of the shell gland, possibly associated with reduced synthesis of 1,25-dihydroxycholecalciferol by the kidney. The maintenance of plasma ionized calcium concentrations does not appear to be of primary importance in this respect.

25-Hydroxyvitamin D3 1-alpha-Hydroxylase↗

PubMed1987

Clonal analysis in vitro of osteogenic differentiation of marrow CFU-F.

Fibroblastic colonies, each of which is derived from a single precursor cell (CFU-F), are formed when suspensions of marrow cells are cultured in vitro. The ability of marrow CFU-F to differentiate in vitro was investigated using the expression of alkaline phosphatase activity as a marker for osteogenic differentiation. In cultures of rabbit marrow cells the colonies formed varied in size, morphology and expression of enzyme activity, indicating that marrow stromal CFU-F are a heterogeneous population. Growth and differentiation of marrow CFU-F can be modified in vitro. Epidermal growth factor increased average colony size and reduced clonal expression of alkaline phosphatase activity to very low levels. Hydrocortisone activated the osteogenic differentiation programme within the cellular progeny of a wide spectrum of CFU-F. The results support the possible development of in vitro clonal methods for the study of differentiation and regulation of the osteogenic and other fibroblastic cell lines of the marrow stromal system.

Alkaline Phosphatase↗