Biomedical subjects
Publications and source records attributed to D E Martin.
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A relatively simple technique for sputum homogenization and dilution is described. Results show that this technique is reliable for isolation and quantitative culture of organisms from cases of chest infection. The technique has resulted in significant reduction in false positive reports, particularly when a system of interpretative reporting is utilized based on 10(7) organisms per millilitre of sputum being accepted as evidence of significant infection.
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The purpose of this investigation was to determine the extent to which listener ratings of the intelligibility of tracheoesophageal puncture (TEP) speech vary as a function of different signal-to-noise ratios. Fifty college students, 25 men and 25 women (Median age = 19.7 years) participated in the study. They were instructed to assign numbers to audio-recorded speech samples in each of nine signal-to-noise ratio conditions (+65 dB, +20 dB, +15 dB, +10 dB, +5 dB, 0 dB, -5 dB, -10 dB, and -15 dB) in two separate magnitude estimation scaling tasks. During Task 1 the subjects rated the intelligibility of a TEP speech sample. In Task 2 the subjects rated the intelligibility of a normal speech sample. The results indicated that as the levels of background noise increased, listener ratings of intelligibility decreased (F 8,392 = 37.84; p < or = .0001).
Though by no means a new concept, the science of callus distraction has stimulated significant interest among surgeons over the past several years. As our knowledge and understanding of the principles of this technique have evolved, the clinical indications have been expanded. In this manuscript, we will illustrate several examples of these broadened indications. An innovative alternative to the Evans opening wedge calcaneal osteotomy, which usually requires bone graft or bone graft substitutes, is presented.
OBJECTIVE: Compare the biomechanical characteristics of screw and wire fixation with and without polymethylmethacrylate (PMMA) re-enforcement for acetabular osteotomy stabilization in dogs. ANIMALS: Pelves removed from 8 adult mixed breed dogs weighing between 25 and 30 kg. PROCEDURE: The pubic symphysis of each pelvis was split and a central transverse acetabular osteotomy was performed. One hemipelvis from each dog was stabilized with the composite fixation (interfragmentary Kirschner wire, two screws and a figure-of-eight orthopedic wire with PMMA). The contralateral hemipelves was stabilized with an interfragmentary Kirschner wire, two screws, and a figure-of-eight orthopedic wire without PMMA. All hemipelves were tested in bending by using a materials testing machine at a cross head speed of 5 mm/min. An extensometer was placed on the dorsomedial surface of the hemipelves centered over acetabular osteotomy to record distraction of the osteotomy during loading. A load/deformation curve and a load/distraction curve was produced for each hemipelvis. The slope for the initial linear portion of the load/deformation curve and the load/distraction curve, yield load and maximum load sustained were compared between repair groups using a paired t-test with P < .05 considered significant. RESULTS: The slope of the load/deformation curve was significantly greater (P = .001) for hemipelves stabilized with the composite fixation (mean +/- SD: 69 +/- 18 N/mm) compared with hemipelves stabilized without PMMA (mean +/- SD: 39 +/- 8 N/mm). There was no significant difference (P = .593) between repair groups in the slope of the load/distraction curves as measured on the extensometer. Yield load was significantly greater (P = .0002) for hemipelves stabilized with the composite fixation (mean +/- SD: 184 +/- 25 N) compared to hemipelves stabilized without PMMA (mean +/- SD: 74 +/- 12 N). Maximum load sustained was also significantly greater (P = .013) for hemipelves stabilized with the composite fixation (mean +/- SD: 396 +/- 71 N) compared to hemipelves stabilized without PMMA (mean +/- SD: 265 +/- 94 N). Failure of hemipelves stabilized with the composite fixation occurred primarily by ventrolateral bending of the cranial and caudal pelvic segments at the osteotomy site. Failure of hemipelves stabilized without PMMA occurred by ventrolateral bending of the cranial and caudal pelvic segments at the osteotomy site with pronounced concurrent ventrolateral rotation of the cranial pelvic segment. CONCLUSION: PMMA improves the mechanical characteristics of acetabular fracture fixation, at least in part by neutralization of rotational forces. The results of this study justify use of PMMA as a component of the composite fixation when repairing acetabular fractures.