Biomedical subjects
Publications and source records attributed to G C McDowell.
Lymph collections following pelvic surgery are usually asymptomatic, but may occasionally produce symptoms requiring invasive therapy. We have successfully obliterated a large lymphocele by employing percutaneous drainage and instilling tetracycline.
The effect of a metal collar on stress distribution with cast post and cores was studied by using three-dimensional photoelastic models of maxillary canine teeth of average dimensions. Standardized parallel post and cores were cemented into the models, with half of the samples incorporating a 1.5 mm metal collar. A 400 gm load was applied to the cingulum of the cores and stresses were frozen in the models. The posts were removed, the teeth were sectioned, and stresses were measured with a circular polariscope. In both groups the greatest stress concentration was found at the lingual apex of the post. On a point by point basis, stresses were higher in the collared specimens. Variation in stress magnitude among five preselected points was greater within the noncollared group.
We reviewed the findings of 217 consecutive pelvic lymphadenectomies performed in patients with clinically localized prostatic carcinoma focusing particular attention on the importance of completely removing the hypogastric lymph nodes and on the operative complications associated with a more extensive dissection. Metastatic disease was identified in the lymph nodes of 127 patients (58.6%). The hypogastric nodes were involved in two thirds of the patients with lymph node metastases, and in 29 percent the hypogastric nodes were the only site of metastasis. No increased operative morbidity was documented as a result of extending the level of the pelvic lymphadenectomy to include the lower hypogastric nodes. We conclude that although the lower hypogastric lymph nodes have not been routinely included in most pelvic lymphadenectomies, their removal is important in detecting metastases.
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Three-dimensional coordinate measuring machines for examining the quality of industrial castings were reviewed. The concept was modified and successfully converted to examine the minute geometric configurations of the surfaces of dental materials. The wear of composites has undoubtedly precipitated this perceptive, thorough study.
A review of the complications of urethral instrumentation performed at our institution during the last 15 years revealed 2 cases of urethrorectal perforation. These patients were managed with loop colostomy and suprapubic cystostomy diversion with excellent healing and no evidence of fistula formation at 24-month followup. This rare complication is described and the principles of diagnosis, prevention and prompt aggressive management are emphasized.
Diuretic renography frequently is used to assess obstruction in hydronephrosis of infancy but it is invalidated by poor renal function, which occurs frequently in this age group. In an attempt to establish a guideline to determine when renal function is too poor in infancy to rely on diuretic renography for an accurate diagnosis we analyzed the slope of the diuretic renographic washout curve of the normal, nonaffected kidney in 33 infants with unilateral hydronephrosis. When the T 1/2 time in the normal, nonaffected kidney was greater than 9 minutes, as occurred in 68 per cent of the infants less than 1 month old, it defined a significant renal functional impairment in both kidneys that interfered with diuretic renographic test interpretation. With time renal function improved and after 4 months of age the T 1/2 time in all nonaffected kidneys became normal and the diuretic renographic diagnosis of obstruction became accurate. Our study indicates that nonaffected kidney T 1/2 time provides a qualitative assessment of global renal function in infancy and defines a level of renal functional maturity that must be achieved to ensure diuretic renographic test accuracy.
Penile necrosis is a rare entity but it may be brought about more readily if certain risk factors are present. Such factors are discussed in this paper and the reader is forewarned about this problem.
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Within the experimental design of this study, the following conclusions were drawn: A unilateral vertical dislodging force applied to a distal-extension removable partial denture is transmitted to the supporting structures with a vertical and horizontal component. The presence of indirect retainers transmits the vertical component of force to both indirect retainer abutment teeth while the horizontal component is transmitted to the indirect retainer and primary abutments on the side opposite the loading force. The presence of indirect retainers reduces the stress to the primary abutment teeth. The presence of indirect retainers distributes stress to more supporting teeth.
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