Biomedical subjects
Publications and source records attributed to K Bishop.
Non-carious, pathological loss of tooth tissue is an increasing problem for the dental profession and the effect of voluntary regurgitation practised by patients with psychological problems is well documented. However, this article describes a patient who repeatedly regurgitated, not because of psychological problems, but to control his body weight as a consequence of his occupation as a horse jockey.
A 90 degree shoulder is probably the most commonly used margin design for porcelain fused to metal (PFM) restorations. However, this design requires the removal of a significant amount of tooth tissue to provide a predictable restoration. This increases the risk of irreversible damage to the pulp, particularly if little tooth tissue is present, for example on exposed roots. In these situations more conservative designs, such as the 135 degree shoulder or deep chamfer, should be considered. Ideally these designs should be used with an all-metal margin since this is associated with the most predictable marginal seal. Where an all metal margin is aesthetically unacceptable a porcelain butt or subgingival margin can be considered. Newer techniques, such as resin bonded crowns, which minimise tooth destruction and provide acceptable aesthetics may be a viable alternative to traditional PFM restorations. Unfortunately, these newer techniques have not been evaluated long-term.
Restoration of dentitions affected by tooth surface loss has been a problem to the dental profession for many years. This problem is likely to increase as the population ages and retains more teeth into old age. This article describes a method of restoring teeth with non-carious loss of tooth tissue whilst conserving the remaining tooth tissue.
This article describes a procedure for making a crown that combines an all-porcelain facial veneer with a metal lingual and occluding surface. The procedure combines both the conventional lost wax technique and the use of a refractory cast for firing porcelain. The crown retains the advantages of the traditional all-porcelain crown restoration but reduces the risk of damage to the opposing teeth associated with an all-ceramic occluding surface. Furthermore, compared with porcelain, the metal surface allows more control over the occlusal and lingual contours during construction of the crown. Although the construction of the anterior crown is described, the procedure is equally applicable to posterior full-coverage restorations.
Sickle cell anemia is a multisystem disease that can affect the oral region. This article reviews previously reported oral complications associated with this disease and describes the cause of these problems. A case history describes a patient with multiple oral problems after a sickle cell crisis. The diagnostic and management problems of this case are highlighted. The need for a multidisciplinary approach to the care of these patients is emphasized.
OBJECTIVE: Initially, the project objective was to develop audit protocols for commonly managed conditions in general practice. However, as the nature of the project evolved these objectives changed to developing consensus guidelines. METHOD: An iterative process was undertaken using mail-outs to gain items for potential inclusion in an audit protocol. This resulted in a change of direction to management guidelines. Consensus, as to the validity of inclusion of items in each guideline, was then achieved by continuing to use an iterative process. RESULTS: Guidelines for 30 presenting complaints were developed. Because a number of differential diagnoses were possible for each complaint, a total of 105 guidelines were developed. A total of 263 general practitioners participated. CONCLUSION: The concept of discriminant actions was developed. It was agreed that this described the clinical decision making that occurs in the general practices of participating practitioners. It is feasible to use an iterative method undertaken by mail to develop consensus guidelines for conditions that are commonly managed by general practitioners.
Genetic instability within malignant cells gives rise to mutant proteins which can be recognized by the immune system. Recognition of tumor-associated antigens by T lymphocytes could thus contribute to the elimination of neoplastic cells. We have developed a molecular genetic intervention for the treatment of malignancies based upon the knowledge that foreign major histocompatibility complex (MHC) proteins expressed on the cell surface are efficient at stimulating an immune response. Expression of this foreign MHC gene within tumors induced a cytotoxic T cell response to the introduced gene. More importantly, the immune system recognized tumor-specific antigens on unmodified tumor cells as foreign. Growth of the tumors diminished, and in many cases, there was complete regression. This research provides evidence that direct gene transfer in vivo can induce cell-mediated immunity against specific gene products, and offers the potential for effective immunotherapy for the treatment of cancer and infectious diseases in man. Our laboratory conducted a phase I clinical trial to determine the safety and efficacy of this treatment in humans. These studies suggest that direct gene transfer provides a safe and feasible approach for the treatment of human cancer. More recent developments using combination gene therapy and the initiation of a second human trial with improvements on this technology have been implemented. Finally, we have begun to define mechanisms of resistance to immune recognition by established malignancies.
Endodontically treated teeth are susceptible to bacterial contamination through exposure to oral fluids. It is crucial, therefore, that restorations placed during and after root canal therapy protect the root canal from oral contamination. This paper highlights the clinical steps necessary to reduce the risk of contamination in root-filled teeth.
The histologic diagnosis of mycosis fungoides (MF) can be difficult to establish and is based on interpretation of numerous subtle changes, most of which may be present to some degree in many inflammatory and neoplastic cutaneous conditions. To reassess the diagnostic criteria for making a histologic diagnosis of MF, we retrospectively reviewed histologic sections from 64 patients with mycosis fungoides (MF+) and compared the findings with sections from 47 patients who were biopsied to exclude MF and were shown not to have the disease (MF-). Patients were selected as MF+ or MF- independent of histologic findings based on the clinical course with at least 3 years of follow-up and immunophenotyping results. Following patient selection, at least two observers reviewed each slide without knowledge of final diagnosis and graded the intensity of approximately 25 histologic parameters. On univariate analysis, the following parameters were significant at beyond the p = 0.01 level: Pautrier's abscesses, haloed lymphocytes, exocytosis, disproportionate epidermotropism, epidermal lymphocytes larger than dermal lymphocytes, hyperconvoluted intraepidermal lymphocytes, and lymphocytes aligned within the basal layer. Haloed lymphocytes proved to be the most robust discriminator of MF from non-MF on multivariate analysis. These findings show that whereas many previously described features do discriminate between MF and inflammatory mimics, others are much less specific. Furthermore, few cases demonstrate all histologic features; for example, Pautrier's microabscesses were seen in only 37.5% of our cases. We conclude that a combination of specific histologic parameters can be used to establish a microscopic diagnosis of MF without the necessity of confirmatory immunophenotyping in the vast majority of cases.
The case history is described of a patient with sickle cell anaemia who developed a unilateral infarct of the mandible following a sickle cell crisis. The interruption of the blood supply resulted in an anaesthesia of the inferior dental nerve and pulpal necrosis of otherwise sound premolar and molar teeth. The diagnostic and management difficulties of the case are discussed, and recommendations are made for treatment of such patients in light of the problems encountered.
The objective of this study was to determine alveolar bone loss from premolar and molar teeth in young adults over a 4-year period between the ages of 15-16 years and 19-20 years. Pairs of posterior bitewing radiographs from 382 subjects aged 15-16 years were examined and the height of the alveolar bone adjacent to mesial and distal tooth surfaces recorded. Repeat radiographs of the same individuals taken 4 years later were then examined and the height of the alveolar bone remeasured. Change in bone height over the study period was computed for individual sites. Clinical data for the cohort were also obtained at both examinations and included plaque score, bleeding on probing and probing depth. Of the 3314 sites, 16.7% exhibited bone gain, 4.5% exhibited no change whilst 78.8% demonstrated bone loss. The overall mean bone loss for all sites combined was 0.407 mm. Bone loss than 0.5 mm was found in 36% of sites, bone loss between 0.5 and 0.99 mm in 33% of sites whilst only 0.5% of sites had bone loss greater than 2 mm. Only one site had bone loss greater than 3 mm. Bone loss was affected significantly by subject (p < 0.001) and by site (p < 0.05) but there was no significant effect for tooth type, whether the surface was mesial or distal or between quadrants. There was significantly more bone loss from around maxillary teeth than mandibular (p < 0.05). There were no significant associations between bone loss and plaque score, bleeding on probing, pocket depth, gender or social class.
OBJECTIVE: To assess the reproducibility of repeat bitewing radiographs. METHODS: Five right and left pairs of posterior bitewing radiographs were taken without the use of beam-aiming or film-holding devices in five dry skulls with complete dentitions. The amelocemental junction (ACJ) and alveolar crest (AC) of every interdental site was traced on projected radiographs and the linear distance between the ACF and AC determined. RESULTS: There was close concordance between the ability to read the ACJ on the approximal tooth surface and the AC. The overall readability of interdental sites was 71% although sites at the extremities of radiographs were often unreadable. Kappa analysis of the readability of alveolar bone height from repeat radiographs was 0.52. There were significant differences in the reproducibility of ACJ and AC measurements from repeated radiographs (p<0.001). Intra-examiner variability was significantly less (p<0.001) than that due to repeat radiography with no significant differences between sites. The standard deviation for all surfaces from repeat readings of the same radiographs was 0.12 mm compared with 0.51 mm from repeat radiography. CONCLUSIONS: In this study a freehand technique produced a degree of imprecision in readings of alveolar bone height from successive films of the same site. In clinical terms, a difference of more than 1.4 mm between pairs of serial measurements from the same site would have to occur in order to be certain that the difference was not measurement error but real bone loss.
BACKGROUND AND DESIGN: There are no large studies evaluating patients with erythrodermic mycosis fungoides and Sézary syndrome to determine the important prognostic factors that may influence survival. This is important since new treatment modalities have been proposed as superior to existing primary therapies. We performed a retrospective cohort study of 106 patients with erythrodermic mycosis fungoides and Sézary syndrome, followed up in the Stanford (Calif) Mycosis Fungoides Clinic, to define the important prognostic factors in this group. RESULTS: Patients younger than 65 years have a more favorable survival profile than those 65 years or older (P < .005). Longer duration of symptoms before diagnosis ( > or = 10 years) tends to be associated with more favorable prognosis (p = .055). Lymph node stage is significantly correlated with survival; patients with overall stage III disease have more favorable prognosis than those with stage IV disease (P < .001). Patients with circulating Sézary cells in their blood have a significantly worse prognosis than those without (P < .005). Patient sex or race had no significant effect on overall survival outcome. Three distinct prognostic groups were identified, "favorable," "intermediate," and "unfavorable," according to the number of unfavorable prognostic factors (P < .005). The median survival in each group is 10.2, 3.7, and 1.5 years, respectively. CONCLUSIONS: In patients with erythrodermic mycosis fungoides and Sézary syndrome, the important prognostic factors are patient age at presentation, the overall stage, and peripheral blood involvement. Survival varies widely, depending on these variables. These prognostic factors should be evaluated when analyzing survival and/or treatment efficacy data of these patients.
PURPOSE: Flow cytometric deoxyribonucleic acid (DNA) content analysis has been shown to be of prognostic importance in some cancers. There have been recent reports of a prognostic importance for DNA content analysis in cervical carcinoma. METHODS AND MATERIALS: We retrospectively reviewed the hospital and radiation oncology records of cervical carcinoma patients who presented between 1984-1990. RESULTS: A total of 101 archival paraffin-embedded blocks were processed, of which 77 were of technical quality for analysis. Thirty-five percent were found to be DNA content aneuploid (DNA-A) and 65% DNA content diploid (DNA-D). No statistical difference was found between the two groups in age at diagnosis, % S-phase, coefficient of variation (CV), or proliferative index (PI). A statistical difference was noted in the G2M phase between the two groups (p = 0.004). The median % S-phase was 8.4% in the DNA-D group. A statistical difference (p = 0.017) in survival was noted between the low and high % S-phase DNA-D groups. In patients who received radiation alone, high-PI patients had improved survival compared to low-PI patients. No statistical difference in survival was noted in the high % S-phase DNA-D group and DNA-A group (p = 0.28). Proportional Hazard (Cox) Regression found clinical stage the only independent prognostic indicator for survival. CONCLUSION: Flow cytometric DNA content analysis is being used more frequently in the management of different malignant tumors. Our study shows that DNA content analysis is useful in determining the prognosis and survival outcomes in cervical carcinomas and may aid in predicting outcome to certain types of treatment regimens.
The Tat protein of human immunodeficiency virus type 1 enhances transcription by binding to a specific RNA element on nascent viral transcripts. Binding is mediated by a 10-amino acid basic domain that is rich in arginines and lysines. Here we report the three-dimensional peptide backbone structure of a biologically active 25-mer peptide that contains the human immunodeficiency virus type 1 Tat basic domain linked to the core regulatory domain of another lentiviral Tat--i.e., that from equine infectious anemia virus. Circular dichroism and two-dimensional proton NMR studies of this hybrid peptide indicate that the Tat basic domain forms a stable alpha-helix, whereas the adjacent regulatory sequence is mostly in extended form. These findings suggest that the tendency to form stable alpha-helices may be a common property of arginine- and lysine-rich RNA-binding domains.