Biomedical subjects

J B Dale

Publications and source records attributed to J B Dale.

75 records · Page 5Linked to original sources

PubMed1976

Effects of prostaglandins E1, E2, and F2alpha on the growth of leukaemia cells in culture.

Prostaglandins E1, E2, and F2alpha (PGE1, PGE2, and PGF2alpha) were shown to inhibit the growth of mouse leukaemia lymphoblasts L5178Y in culture. The effects of PGE1 and PGE2 were greater than that of PGF2alpha. PGE1 and PGE2, at the concentration of 100 mug per ml showed significant inhibitory effects on the rates of incorporation of tritiated thymidine, uridine and leucine. At concentrations of 50 and 25 mug per ml, there was significant inhibition of thymidine and uridine incorporation, but not of leucine, PGF2alpha showed significant inhibition of thymidine and uridine incorporation but not leucine incorporation, in all 3 concentrations studied (100, 50, and 25 mug/ml). The ability of the cells to form colonies in soft agar was significantly inhibited by PGE1 and PGE2 at concentrations as low as 1-8 mug/ml. For F2alpha, however, a concentration as high as 56mug/ml was required to show inhibitory effect, but at 1-8 mug/ml it was found to be stimulatory.

Cell Count↗

PubMed1975

Canine cyclic haematopoiesis: marrow transplantation between littermates.

Dogs affected with cyclic haematopoiesis (CH) and experiencing recurrent 12-day cycles of neutropenia were supralethally irradiated and transplanted with marrow from their normal littermates. Following transplantation of the normal marrow, dogs with CH experienced no further cycles of neutropenia. Platelet and reticulocyte numbers also ceased to fluctuate cyclically in these dogs. The marrows of dogs with CH were transplanted into unaffected supralethally irradiated littermates. Prompt engraftment occurred in the recipient dogs with subsequent cyclic rises and falls of the numbers of platelets, reticulocytes and neutrophils. In the post-transplant period, immunosuppressant drugs were not used in three of the recipients and the fourth received only a single 5 mg dose of methotrexate.

Animals↗

PubMedDate not supplied

Attachment of Streptococcus pyogenes to mammalian cells.

Accumulated evidence indicates that lipoteichoic acid (LTA) is centrally involved in the attachment of group A streptococci to epithelial cells of the host. The binding of LTA to a variety of host cells is mediated by the glycolipid end of the LTA molecule, which can form ionic complexes with streptococcal surface proteins, permitting the reorientation of the LTA to expose some of its lipid ends toward the surface of the organism. The ability of albumin to block the adherence of streptococci to epithelial cells and to bind to LTA-M protein but not deacylated LTA-M protein complexes supports the idea that the lipid ends remain free to interact with cell membrane receptors. The cell membrane receptors appear to consist of a lipid-binding region(s) on fibronectin molecules on the surfaces of oropharyngeal epithelial cells. Although streptococci exhibit LTA-sensitive binding to phagocytic cells in a serum-free system, in the presence of serum, they do not; rather, complement bound to the streptococcal cell surface is required for recognition by phagocytes. The binding of fibrinogen to the M protein on the surface of M-rich streptococci specifically blocks the recognition of the organisms by opsonic complement components. The attachment of M-rich streptococci to phagocytic cells requires the development of antibodies directed specifically toward regions of M protein not blocked by fibrinogen.

Adhesiveness↗