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G Bancroft

Publications and source records attributed to G Bancroft.

12 recordsLinked to original sources
PubMed2007

Fracture healing assessment comparing stiffness measurements using radiographs.

Based on published reports, we presumed radiographs would be unreliable as a sole measure of fracture healing. To confirm this presumption we correlated radiographic fracture healing assessments with fracture stiffness measurements. We showed 100 plain radiographs of fractures with corresponding fracture stiffness measurements to 92 observers. The radiographs were shown twice to assess intraobserver variation. Observers were divided into three groups and asked to determine whether each fracture had healed (union corresponded to a fracture stiffness greater than 15 nm/degrees). Group 1 based fracture healing on the general appearance of healing. Groups 2 and 3 assessed fracture healing based on the number of cortices bridged by callus. In Group 2, the fracture was considered healed if two or more cortices were bridged on both radiographic views and in Group 3 if three or more cortices were bridged by callus. All groups performed poorly. There was no difference in terms of correct prediction of healing between methods, although there was a trend toward more reliability with cortical callus bridging assessment. We found substantial intraobserver variability, which improved using cortical bridging methods. Observers were less reliable at predicting healing when there was a metaphyseal extension to a diaphyseal fracture.

Bony Callus↗
PubMed1997

T-cell-independent granuloma formation in response to Mycobacterium avium: role of tumour necrosis factor-alpha and interferon-gamma.

We used Mycobacterium avium infection in severe combined immunodeficiency (SCID) mice to examine T-cell-independent mechanisms of inflammatory cell recruitment. SCID mice infected with a virulent strain of M. avium (TMC724) were able to recruit macrophages to sites of mycobacterial replication and formed organized and coherent granulomas in the absence of functional T cells. Phagocyte recruitment was almost totally ablated by neutralization of either tumour necrosis factor-alpha (TNF-alpha) or interferon-gamma (IFN-gamma) in vivo demonstrating that granuloma formation was dependent on the presence of these cytokines. This was concomitant with a reduction in the in situ cytokine mRNA levels otherwise induced in infected mice, for chemokines, pro-inflammatory and regulatory cytokines, including TNF-alpha, IFN-gamma, macrophage inflammatory protein-1 alpha, interleukin-1 beta (IL-1 beta) and IL-10. Furthermore, in vivo treatment of infected mice with anti-asialo GM-1 antisera, which depletes natural killer (NK) cells, prevented recruitment of inflammatory cells. In vitro studies confirmed that M. avium was able to elicit IFN-gamma from SCID spleen in a dose-dependent manner. These data show for the first time that secretion of IFN-gamma from NK cells can mediate a T-cell-independent pathway of granuloma formation and cellular infiltration in response to mycobacteria.

Animals↗
PubMed1982

Incubation of trypanosome-derived mitogenic and immunosuppressive products with peritoneal macrophages allows recovery of biological activities from soluble parasite fractions.

This report describes further attempts to define the nature of the parasite product(s) responsible for the extensive changes in lymphoid tissue in mice during infection with Trypanosoma brucei. As previously described, potent mitogenic and immunosuppressive effects are induced by a trypanosome-derived crude membrane fraction in vivo. There was no enrichment in these activities when purified parasite surface membranes were used. Mitogenic activity can be recovered from soluble trypanosome material only when it is incubated with peritoneal macrophages before transfer into syngeneic recipients. Thus, by encouraging association with a critical target cell, soluble parasite products can be studied, and their active components can be separated by conventional methods. Preliminary fractionation of high-spin trypanosome supernatant over Sepharose 4B confined the mitogenic activity to the high-molecular-weight fraction, which is a macromolecular complex of proteins, glycoproteins, and lipid. Extracted lipid from this material was able to significantly suppress a primary immunoglobulin G anti-sheep erythrocyte response. The activity was periodate sensitive and pronase resistant. The use of macrophages in vitro may be a general method whereby important biological activities lost as a result of fractionation procedures can be recovered and the active components studied in greater detail.

Animals↗