Photography by Ewen Bell


What's Up Doc

Who would have thought that a career in medical research would prepare me for travel journalism, but the fact is that I would never have learned to write if not for the riggers of scientific communications. It's exciting stuff, be warned...

Production of prostaglandin f2alpha and its metabolite by endometrium and yolk sac placenta in late gestation in the tammar wallaby, Macropus Eugenii.
Shaw G, Gehring HM, Bell EC.
Department of Zoology, The University of Melbourne, Parkville, Victoria 3052, Australia.
In this study, we investigated production of prostaglandin (PG) F2alpha and its metabolite, PGFM, by uterine tissues from tammar wallabies in late pregnancy. Endometrial explants were prepared from gravid and nongravid uteri of tammars between Day 18 of gestation (primitive streak) and Day 26.5 (term) and were incubated in Ham's F-10 medium supplemented with glutamine and antibiotics for 20 h. PGF2alpha and PGFM in the medium were assayed by specific, validated RIAs. Control tissues (leg muscle) did not produce detectable amounts of either PG. Both gravid and nongravid endometria secreted PGF2alpha, and production increased significantly in both gravid and nongravid uteri towards term. PGFM was produced in small amounts by both gravid and nongravid uteri, and the rate of production did not increase. Neither oxytocin nor dexamethasone stimulated PG production in vitro in any tissue at any stage. Thus, the surge in peripheral plasma PGFM levels seen at parturition may arise from increased uterine PG production, but further study is needed to define what triggers this release.
Biol Reprod. 1999 Mar;60(3):611-4

Production and characterization of WEG-1, an epidermal growth factor/transforming growth factor-alpha-responsive mouse uterine epithelial cell line.
Wegner CC, Cherington V, Clemens JW, Jacobs AL, Julian J, Surveyor GA, Bell EC, Carson DD.
Department of Biochemistry and Molecular Biology, M.D. Anderson Cancer Center, Houston, Texas 77030, USA.
Uterine epithelial cells (UEC) isolated from 6-week-old CF-1 mice were immortalized using retroviral-mediated transfection of SV40 large T-antigen. One line, WEG-1, retained epithelial morphology and reacted with antibodies to cytokeratins 18, 19, laminin, fibronectin, and beta-catenin. In addition, WEG-1 cells displayed strong nuclear immunoreactivity to SV40 large T-antigen, confirming integration of the retrovirus vector and expression of this gene. WEG-1 cells were negative for nonepithelial markers such as desmin and factor 8. WEG-1 cells did not proliferate in serum-free medium; however, addition of 0.5% FBS supported proliferation to the same extent as 10% FBS. Addition of 50 ng/ml epidermal growth factor to medium containing 0.5% charcoal-stripped FBS restored proliferation comparable with 0.5% whole FBS. Epidermal growth factor or transforming growth factor-alpha (50 ng/ml), but not transforming growth factor-beta, leukemia-inhibiting factor, or fibroblast growth factor, induced the secretion of three proteins (M(r) approximately to 158K, 148K, and 36K). Comparison of protein secretions of WEG-1 cells and UEC showed shared as well as distinct bands. Like UEC, WEG-1 cells secreted PGF2a and PGE2 and expressed PG GH synthase-2. Unlike UEC, WEG-1 cells showed no apical/basal preference for either uptake of methionine or secretion of proteins. The absence of immunoreactive E-cadherin or zona occludens-1 was consistent with the absence of cell polarity in WEG-1 cells. Primary UEC, which polarize in vitro, do not support blastocyst attachment. WEG-1 cells, although not polarized in vitro, also exhibited delayed blastocyst attachment compared with nonuterine cell lines, suggesting that WEG-1 cells partially retained some aspects of UEC function relevant to embryo attachment. WEG-1 cells expressed messenger RNA for Muc-1, an UEC mucin suggested to have antiadhesive properties. Furthermore, WEG-1 cells did not display high affinity heparin binding sites, an activity associated with embryo attachment. WEG-1 cells may provide a model for studying various aspects of UEC function and murine embryo attachment.
Endocrinology. 1996 Jan;137(1):175-84

Characterization of the interaction between the Staphylococcus aureus clumping factor (ClfA) and fibrinogen.
McDevitt D, Nanavaty T, House-Pompeo K, Bell E, Turner N, McIntire L, Foster T, Höök M.
Department of Biochemistry and Biophysics, Institute of Biosciences and Technology, Texas A & M University, Houston 77030-3303, USA.
The ability of Staphylococcus aureus to adhere to adsorbed fibrinogen and fibrin is believed to be an important step in the initiation of biomaterial and wound-associated infections. In this study, we show that the binding site in fibrinogen for the recently identified S. aureus fibrinogen-binding protein clumping factor (ClfA) is within the C-terminus of the fibrinogen gamma chain. S. aureus Newman cells expressing ClfA adhered to microtitre wells coated with recombinant fibrinogen purified from BHK cells, but did not adhere to wells coated with a purified recombinant fibrinogen variant where the 4 C-terminal residues of the gamma chain were replaced by 20 unrelated residues. In addition, a synthetic peptide corresponding to the 17 C-terminal amino acids of the fibrinogen gamma chain effectively inhibited adherence of ClfA-expressing cells to fibrinogen. In western ligand blots, a recombinant truncated ClfA protein called Clf33 (residues 221-550) recognized intact recombinant fibrinogen gamma chains, but failed to recognize recombinant fibrinogen gamma chains where the 4 C-terminal amino acids were altered by deletion or substitution. Previous studies have shown that the C-terminal domain of fibrinogen gamma chains contains a binding site for the integrin alphaIIb beta3 (glycoprotein gpIIb/IIIa) receptor on platelets [Kloczewiak, M., Timmons, S., Bednarek, M. A., Sakon, M. & Hawiger, J. (1989) Biochemistry 28, 2915-1919; Farrell, D. H., Thiagarajan, P., Chung, D. W. & Davie, E. W. (1992) Proc. Natl. Acad. Sci. USA 89, 10729-10732; Hettasch, J. M., Bolyard, M. G. & Lord, S. T. (1992) Thromb. Haemostasis 68, 701-706]. We now show that Clf33 inhibits ADP-induced, fibrinogen-dependent platelet aggregation in a concentration-dependent manner and inhibits adhesion of platelets to immobilized fibrinogen under fluid shear stress, indicating that the binding sites for the platelet integrin and the staphylococcal adhesin overlap. The interaction between Clf33 and fibrinogen was further characterized using the BIAcore biosensor. When soluble Clf33 was allowed to bind to immobilized fibrinogen, a Kd of 0.51 +/- 0.19 microM was experimentally determined using equilibrium binding data. It was also shown that the synthetic C-terminal gamma-chain peptide effectively inhibited this interaction.
Eur J Biochem. 1997 Jul 1;247(1):416-24