Biomedical subjects
A L Allen
Publications and source records attributed to A L Allen.
The management of knee flexion contractures in haemophilia: brief report.
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Antigenic variation in clones of Trypanosoma brucei grown in immune-deficient mice.
We have produced monoclonal antibodies against six variant surface glycoproteins from early variant antigen types (VATs) of the IsTaR 1 serodeme of Trypanosoma brucei brucei. We have used these in fixed cell immunofluorescence assays to follow the VAT composition of populations of each early VAT when passaged through irradiated mice. The IsTat 1.A and 1.7a populations were stable for more than 30 days (approximately 150 generations), but 1.1a, 1.3a, 1.5a, and 1.11a all changed to 1.A within this time. The time and rate of this antigenic switch were characteristic for each VAT. Growth rates of the VATs were determined when they were both grown separately and grown with 1.A. It appeared that the order of growth rates was 1.7a greater than 1.A = 1.1a greater than 1.11a greater than 1.5a greater than 1.3a. We have generated theoretical curves for the replacement of one VAT by another based on differences in their growth rates and the rate at which one VAT switches to another (switch frequency). These curves closely match those derived experimentally. We postulate that the differences in growth rates between VATs and the different switch frequencies for VATs may be sufficient to generate the loosely defined sequence of VATs seen in chronic infections.
Detection of oral anaerobic spirochetes in dental plaque by the indirect fluorescent-antibody technique.
The indirect fluorescent-antibody technique was found to be a rapid and sensitive tool for the detection of oral anaerobic spirochetes in dental plaque.
Histologic assessment of autogenous bone graft--a case report and critical evaluation.
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Periodontosis: a case report with scanning electron microscopic observations.
A tooth and associated periodontal tissues from a patient with the diagnosis of periodontosis was subjected to scanning electron microscopic evaluation after reflection of the soft tissue portion of the lingual defect. The cemental surface of the apical portion of the lesion was found to be populated by markedly similar rod-shaped organisms. The microorganisms were observed to be continuously present in a coronal-apical direction as the transition from cementum to the attached soft tissues at the base of the defect were examined. These findings provide additional evidence that the lesion of periodontosis is characterized by a rather distinct microbial population of rod-shaped organisms located predominately at the base of the defect.
The incidence of transient bacteremia during periodontal dressing change.
Twenty patients undergoing treatment for periodontal disease and not receiving antibiotics, volunteered to donate blood for culture studies to determine the incidence of transient bateremia during the dressing change and suture removal 1 week after periodontal surgery. Each patient contributed 20 ml of blood prior to the dressing change and an additional 20 ml during suture removal. The samples were cultured both aerobically and anaerobically. Bacteria were demonstrated in five out of 20 postoperative cultures (25%). This incidence approached statistical significance at the 0.05 level using Chi-square analysis with a Yates correction. All species were identified as belonging to the genus streptococcus. None of the blood specimens obtained prior to dressing change exhibited bacterial growth. Although the incidence of bacteremia in this study was not statistically significant at the 0.05 level, it may be clinically significant that five out of 20 patients demonstrated transient bacteremia. Commercial materials and equipment are identified in this report to specify the investigative procedures. Such identification does not imply recommendation or endorsement or that the materials and equipment are necessarily the best available for the purpose. Furthermore, the opinions expressed herein are those of the author and are not to be construed as those of the Army Medical Department.
Internal root resorption after vital root resection.
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Pilot scale investigations and economics of cellulase production.
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An investigation of the clinical and histologic effects of selected dentifrices on human palatal mucosa.
A study was undertaken in 24 human volunteer subjects to determine the possible effects of selected commercially available dentifrices on clinically normal masticatory mucosa. An acrylic stent was fabricated which was designed to hold four test dentifrices in close apposition to the palatal tissues for 1 hour. Evaluation approximately 8 hours later revealed pathologic responses which were evident clinically and histologically. 1. Clinically, palatal tissues exposed to Crest were not distinguishable from control areas, while Colgate (mfp), MacCleans, and Ultra Brite produced erythematous changes which were statistically significant when compared with adjacent control sites. 2. Histologically, epithelial changes were seen within the test sites which ranged from a parakeratin-like surface layer to necrosis and intraepithelial abcess formation. Control sites consisted of normal orthokeratinized palatal mucosa in all cases. 3. The more severe microscopic reactions were noted with MacCleans and Ultra Brite, while the milder reactions were associated with Colgate (MFP). Crest infrequently produced a parakeratin-like response. The response was not statistically significant when compared with controls. 4. The clinical and histologic reactions were generalized throughout the test population, suggesting that the responses were not due to individual hypersensitivity but due to irritation from one or more of the dentifrice components. Although the clinical significance of these findings could not be readily assessed, the potential for irritation of human palatal mucosa by selected dentifrices has been demonstrated. These findings support the suggestion by the World Workshop in Periodontics (1966)20 that efforts should be directed to the development of dentifrice materials less harsh to the oral tissues.