A device to apply user-specified strains to biomaterials in culture.

An apparatus was developed to apply user-specified displacements to biomaterial samples in culture. The device allowed cyclic waveforms of bandwidth 0 Hz to 20 Hz to be applied under physiologic thermal (37.5 degrees C) and [CO2] (5%) conditions. For a 0 Hz to 20 Hz bandwidth signal similar in shape to a ventricular pressure waveform, the mean displacement error was 0.26% of the full-scale output. The maximum overshoot was 0.700%. Environmental system evaluation tests demonstrated a specimen cartridge temperature of 37.20 +/- 0.15 degrees C during cyclic loading and 37.23 +/- 0.21 degrees C during static conditions. [CO2] was 5.29 +/- 0.54% during cyclic loading and 5.25 +/- 0.61% during static conditions. Laminar flow applied at the loading rod entrances to the specimen cartridge ensured the sample remained sterile during testing. As a preliminary evaluation, polyurethane samples were seeded with fetal foreskin fibroblasts and subject to intermittent cyclic displacements. Results demonstrated enhanced cell proliferation and increased [PGE2] for samples subjected to 10% strain compared with unstrained controls. A next step will be to evaluate cell response sensitivity to strain magnitude, duration, direction, and frequency. The long-term intent is to establish mechanical loading configurations that induce acceptable or adaptation-inducing responses for use in implant design and tissue engineering applications.

Reactions of polyclonal and neutralizing anti-p54 monoclonal antibodies with an isolated, species-specific 54-kilodalton protein of Chlamydia pneumoniae.

A recently described 54-kDa protein has been detected in six type strains and three patient isolates of Chlamydia pneumoniae by immunoblotting with sera from patients positive for antibodies to C. pneumoniae by the microimmunofluorescence test. This protein was not found in either C. trachomatis E or C. psittaci Z 432 as an antigen, confirming its species specificity. The 54-kDa protein was isolated by continuous-elution electrophoresis and immunoglobulin G monoclonal antibodies (MAbs) against the isolated antigen were produced. MAb 8B11E6 reacted only with the 54-kDa band of C. pneumoniae and not with C. trachomatis E or C. psittaci in a Western immunoblot assay. This antibody was purified and tested for neutralizing activity together with three additional anti-p54-active MAbs (8B11E6, 8B11B4, and 10F1C1). In Buffalo green monkey cells, all of the MAbs significantly reduced the infectivity of C. pneumoniae elementary bodies, whereas no neutralizing activity could be observed with C. trachomatis E or C. psittaci Z 432. These results not only confirm the species specificity of the 54-kDa protein but also indicate that this protein might play an important role in the pathogenesis of C. pneumoniae infection. Furthermore, the results suggest a possible protective role of anti-p54 antibodies in an adaptive immune response.

Effect of retraction procedures on the periodontium in humans.

On the basis of wound healing and gingival recession caused by the three procedures, the copper-band retraction method was the most satisfactory. This tentative conclusion is based on the following reasons: 1. Retraction methods must be evaluated relative to the impression procedure and fit of the restoration. The long-range effects of the marginal fit are probably the most important factor for enhancing periodontal health. 2. This study involved only healthy periodontia of adolescent patients. Different healing might be observed in tissues characterized by gingivitis or periodontitis. 3. A broader study involving a greater range of procedures and conditions is recommended to evaluate each retraction technique. 4. This study involved teeth which had an adequate zone of attached gingiva. More complicated healing and perhaps altered sequences might be observed if the procedures were performed on gingival margins of alveolar mucosa, thin gingival walls, or areas of root prominence and thin cortical bone.