Biomedical subjects
Publications and source records attributed to R R White.
We report an illustrative case of pachyonychia congenita, with a description of the presenting complaints, the associated physical findings, the rationale for surgical treatment, and the technical aspects of the surgical treatment.
Rabbit polymorphonuclear leukocytes were incubated with a sonically treated suspension of pooled dental plaque to determine if the plaque would induce release of lysosomal enzymes from the polymorphonuclear leukocytes. Cells incubated with plaque at 37 degrees C released significantly greater amounts of the lysosomal enzymes, beta-glucuronidase and lysozyme, than did cells incubated with plaque at 0 degrees C or without plaque at 37 degrees C. This response was both dose and time dependent. Release of the cytoplasmic enzyme lactate dehydrogenase was minimal, and there were no significant differences in lactate dehydrogenase release between cells at 0 and 37 degrees C, or without plaque. These results indicate that dental plaque can induce the selective release of lysosomal enzymes, which could be involved in the periodontal injury produced by dental plaque.
Phatocytosis by a human gingival epithelial-like cell line in tissue culture was studied using latex beads as a marker. Electron microscopic and chemical analyses revealed that the cells ingested the beads in a quantitative and reproducible manner. This phagocytosis system is potentially useful for studying the effects of dental plaque on cell metabolism.
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With regard to the principal purpose of this investigation, it is apparent that exposure to mercury during the preparation of silver amalgam definitely presents an additional occupational hazard as an allergen in the dentist. The fact that the dental students who were the volunteers in this study received only a small fraction of the exposure to mercury that the practicing dentist receives does emphasize the potential of this allergen in actual dental practice. Recent publicity concerning the toxioogenicity of mercury has led to a call for improved mercury hygiene in the dental operatory. The allergenic potential of mercury, as reported in this paper, accentuates the need for such an improvement.
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Primary tumors of the small bowel are uncommon, representing less than 6 per cent of all gastrointestinal tumors and less than 2 per cent of all malignant gastrointestinal tumors. This report concerns a twenty-five year survey of our clinical records from 1946 to 1971 which revealed 140 primary small bowel tumors, excluding periampullary tumors. Fifty-two of the neoplasms (37 per cent) were benign; eighty-eight (63 per cent) were malignant and included twenty-eight adenocarcinomas (31.8 per cent), twenty-four lymphosarcomas (27.3 per cent), nineteen carcinoids (21.6 per cent), and ten leiomyosarcomas (11.4 per cent). The average age at the time of diagnosis was 56.9 years for patients with benign tumors and 55.9 years for those with malignant tumors. The illusive and obscure nature of small bowel tumors is illustrated by the fact that 63.3 per cent of patients with benign lesions and 47.6 per cent of those with malignant lesions had symptoms for more than six months before the diagnosis was made. Bleeding was the most common present complaint in patients with benign neoplasms (52.9 per cent) whereas patients with malignant lesions more often had symptoms of obstruction (50.6 per cent). Most of the benign lesions were located proximally in the small bowel (duodenum, 34.6 per cent; ileum, 11.5 per cent), and most of the malignant lesions were located distally (duodenum, 17.0 per cent; ileum, 61.4 per cent). Treatment of patients with malignant lesions was radical excision whenever possible. Adjunctive radiation therapy was used for those with lymphoma. A second benign or malignant tumor occurred in 42.9 per cent of the patients with primary small bowel tumors. The average period of survival after diagnosis of a malignant small bowel tumor was 5.03 years: for patients with adenocarcinoma, 3.6 years; lymphosarcoma, 1.3 years; carcinoid, 6.8 years; and leiomyosarcoma, 8.3 years.
We analyzed the records of 242 consecutive patients with adenocarcinoma of the stomach operated on for cure. We correlated survival with several factors, including the type of primary lesion, the operation performed, operative mortality, state of regional lymph nodes, margins of the resected specimens, and duration of preoperative symptoms. Overall survival at 5 years was only 18.6% and at 10 years was 7.1%. Patients with small malignant gastric ulcers, however, enjoyed increased survival at 5 years (53.8%) and at 10 years (15.0%). Overall operative mortality was 7.1%, but was 0% for patients with small malignant gastric ulcers. Even with large or high-lying lesions, radical operation can be accomplished with acceptable mortality and definite chance for cure. Thirteen of 45 five-year survivors had positive lymph nodes, and 7 of the 45 had positive margins of resection. Longer symptomatic preoperative periods, correlated positively with increased survival. Thirty patients with preoperative symptomatic periods exceeding 24 months had a 30.0% 5-year survival. Perhaps some of these lesions underwent malignant change in areas of symptomatic benign disease. We advocate early operation for gastric ulcers which do not heal promptly and stay healed.
Twenty-one populations of the checkerspot butterfly, Euphydryas editha, and ten populations of Euphydryas chalcedona were sampled for genetic variation at eight polymorphic enzyme loci. Both species possessed loci that were highly variable from population to population and loci that were virtually identical across all populations sampled. Our data indicate that the neutrality hypothesis is untenable for the loci studied, and therefore selection is indicated as the major factor responsible for producing these patterns. Thorough ecological work allowed gene flow to be ruled out (in almost all instances) as a factor maintaining similar gene frequencies across populations. The Lewontin-Krakauer test indicated magnitudes of heterogeneity among standardized variances of gene frequencies inconsistent with the neutrality hypothesis. The question of whether or not to correct this statistic for sample size is discussed. Observed equitability of gene frequencies of multiple allelic loci was found to be greater than that predicted under the neutrality hypothesis. Genetic differentiation persisting through two generations was found between the one pair of populations known to exchange significant numbers of individuals per generation. Two matrices of genetic distance between populations, based on the eight loci sampled, were found to be significantly correlated with a matrix of environmental distance, based on measures of fourteen environmental parameters. Correlations between gene frequencies and environmental parameters, results of multiple regression analysis, and results of principle component analysis showed strong patterns of association and of "explained" variation. The correlation analyses suggest which factors might be further investigated as proximate selective agents.
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