Biomedical subjects
Publications and source records attributed to J Anderson.
The potential of local radiotherapy with intraoperative electron beam irradiation and trans t-tube iridium(192) brachytherapy for the management of carcinoma of the extrahepatic ducts is illustrated by this case report.
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Two easily-computed approximate methods of obtaining an estimate of the ratio of the hazard rates for two treatments in survival analysis are compared, by simulation, with the partial maximum likelihood (CML) estimator which assumes the Cox model with no covariates. The two methods studied are the Mantel-Haenszel estimator, and the O/E method which employs the ratio of the 'relative death rates' for the two treatments. Uncensored and censored cases are examined for both continuous and tied data with the assumption of either an underlying exponential distribution or a Weibull distribution with shape parameter 2. The O/E method is biased but, within the range of values of the ratio of the hazard rates of interest in clinical trials, it is more efficient in terms of mean square error than either CML or the Mantel-Haenszel method for all but the largest trials. The Mantel-Haenszel method is minimally biased, gives answers very close to those obtained using CML, and may be used to provide satisfactory approximate confidence intervals.
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Each year medical schools in the United Kingdom select about 3800 entrants from about 12 000 applicants. The problem of selection is thus substantial, but the objectives, policies, and practices of different medical schools differ sharply and details of the procedures used are rarely made clear. There is no reliable or up-to-date information available for schools, careers of advisers, and prospective candidates to keep abreast of these practices and policies and of changes made to them. A code of practice for medical student selection might be helpful and would not only facilitate discussion about the appropriateness and fairness of the widely differing practices but make it easier to evaluate the procedures used. Such a code should list the academic and personal requirements for the school, state any quotas for types of entrants, and describe the selection procedures.
Preliminary experience with fetoscopy and fetoplacental blood sampling in 23 midtrimester pregnant baboons demonstrated the procedure to be successful in 19 cases (83%); seven serious complications (30%) developed, most of which might well have been avoided with operative experience and other complimentary procedures.
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The sialic acid content of erythrocytes from healthy individuals of different blood types and of patients with known hematological disorders has been determined. The sialic acid was completely released enzymatically with sialidase and quantitated by the thiobarbituric acid method. The sialic acid content of erythrocytes was constant irrespective of ABO blood type, or anticoagulant used; viz, 0.85-0.92 mumoles/ml of packed erythrocytes or 46-53 X 10(6) sialyl residues per cell. Deviations from these normal values were obtained with erythrocytes from patients with a variety of hematological disorders. Patients with the following disorders have significantly (P less than 0.01) lower sialic acid values compared to erythrocytes from healthy individuals (given in the order of decreasing sialic acid content): sickle cell anemia, acute lymphocytic leukemia, chronic lymphocytic leukemia, acute myelomonocytic leukemia, non-Hodgkin lymphocytic lymphoma, chronic granulocytic leukemia, acute myelocytic leukemia, leukemia, and Hodgkin disease.
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A pilot study of the toxicity and efficacy of a new treatment schedule for childhood non-Hodgkin's lymphoma was conducted by members of the Children's Cancer Study Group (CCSG) prior to its use in a randomized phase III trial. Chemotherapeutic agents used were cyclophosphamide (CPM), vincristine (VCR), and prednisone, together with intravenous (IV) and intrathecal methotrexate (IT MTS). Radiation therapy was also employed. From September 1976 to April 1977, 27 eligible, newly diagnosed patients with non-Hodgkin's lymphoma were entered onto this pilot study. Toxicity was acceptable with minor adjustments in dosage and timing of the myelosuppressive agents. Fourteen of the 22 patients entered onto maintenance remain entirely disease-free, and all have completed the prescribed course of chemotherapy. None of the 12 patients characterized as having a "favorable" prognosis has relapsed, with a median follow-up of 27 months from on study.
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Some problems common to many disciplines are briefly examined. One of the problems, that of an information overload, was recognized in medical education already twenty years ago; since then the situation has become much more acute. We have attempted to give a numerical value to the information content of a number of courses and these highlight the overload in the medical course.
Eighteen patients, moderately to heavily infected with onchocerciasis, were treated with a standard course of diethylcarbamazine citrate (DEC-C). In addition to the well recognised systemic reactions to treatment, the following ocular changes occurred during therapy: (1) Transient pigment epithelial lesions were detected in 7 patients by fluorescein angiography. (2) Optic disc leakage, as shown by fluorescein angiography, developed in 9 patients, and increase of pre-existing leakage was demonstrated in 3 further patients. (3) Visual field loss was documented in 5 patients. These observations have grave implications for DEC-C therapy in onchocerciasis. They emphasise the need for great caution in its use in the treatment of onchocerciasis in heavily infected patients and for close supervision of ocular function during therapy.