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Is the theory-practice gap being bridged now that lecturer-practitioner posts exist in many parts of the country? Jenine Willis finds out how some practitioners are coping with the demands of the job.
BACKGROUND: Adenoma of the iris pigment epithelium (IPE) is an uncommon lesion that can simulate iris or ciliary body melanoma, melanocytoma, and pigment epithelial cyst. OBJECTIVES: To evaluate the clinical and pathological features and prognosis of adenoma of the IPE in patients managed by us and to elucidate the features that help to differentiate this tumor from iris melanoma and other similar conditions. PATIENTS AND METHODS: The medical records of 20 patients with adenoma of the IPE were reviewed, and the clinical and histopathologic features were tabulated. RESULTS: Ten patients were male and 10 were female, with a mean age of 60.0 years (range, 11-85 years). All patients were referred because of suspected iris or ciliary body melanoma. All lesions were solitary and unilateral. Sixteen were located in the peripheral iris; 2, in the midzone; and 2, near the pupillary margin. Clinically, all tumors were abruptly elevated, all but 1 were dark gray to black, and all had a smooth, but sometimes multinodular, surface. The tumors caused thinning or complete effacement of the overlying iris stroma, but they did not directly involve the stroma. They typically blocked light with transillumination. On ultrasound biomicroscopy findings, adenoma of the IPE shows a solid tumor pattern, sometimes with small cystoid spaces. The tumor was managed by local resection in 2 patients and observation in 18, all of whom have been stable, with follow-up ranging from 6 months to 9 years. Histopathologic examination revealed a tumor originating in the IPE consisting of cords of pigment epithelial cells separated by septae of connective tissue. CONCLUSIONS: Adenoma of the IPE usually has characteristic features that should differentiate it from iris melanoma, ciliary body melanoma, iris melanocytoma, and iris cyst. Adenoma of the IPE is a benign tumor that may remain relatively stable for years.
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The optimal therapy for hypopharyngeal carcinoma depends on its staging. For early-stage disease, radiotherapy and surgery achieve similar results. Radical surgery followed by radiotherapy is applicable in the management of patients with advanced-stage disease. Chemoradiation aiming to preserve the larynx can only be performed for selected patients and in well-equipped institutions. Thorough understanding of pathological behavior of hypopharyngeal carcinoma, its submucosal tumor extension, and its high propensity to metastasize to cervical lymph nodes allows head and neck surgeons to choose optimal surgical treatment. Lymph node status determines the type of neck dissection required while location and size of the primary tumor determine the extent of resection and choice of reconstruction procedure. Adequate tumor extirpation with less extensive and invasive procedures preserving unaffected normal tissue contribute to more tumor control and less morbidity.
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Explore the source record for details and available documents.
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In 1934 the Chicago physician R.T. Woodyatt suggested that 'The history of diabetes has been marked by recurrence of certain ideas which decline and disappear; only to go through a similar cycle again in an altered form in a new generation'. This has been particularly true of the concept of brittle diabetes which Woodyatt himself introduced in the 1930s. He never wrote a paper on the subject but contemporaries understood it to refer to excessive fluctuations of blood sugar which could not be explained by patient or physician errors; the cardinal feature was unpredictability and unexpected hypoglycaemic reactions. Also in the 1930s, practitioners of the newly formed psychosomatic movement took an interest in the effect of emotional factors on the course of diabetes and, in particular, patients who were 'difficult' or 'refractory'. What marked 'difficult' patients was that they did not follow their doctor's instructions or had recurrent diabetic ketoacidosis. By the 1950s the question was whether there were two distinct groups of patients; one whose lability could be cured by adjusting insulin, diet, and exercise, and another whose lability had an emotional origin. Did proponents of the organic school have patients (unreported) in whom lability had an obvious emotional cause or, conversely, were the psychosocial problems which the psychiatrists unearthed a consequence rather than a cause of the instability? My experience with a patient with factitious hypoglycaemia which remained undetected for weeks in a clinical research unit suggested that neither close observation nor screening by a psychiatrist could rule out factitious disease. Therefore in 1977 I suggested that the definition of brittle diabetes should be a patient whose life was 'constantly disrupted by episodes of hypo- or hyperglycaemia, whatever their cause'. This was widely accepted and there was a subtle shift towards regarding brittle diabetes as synonymous with recurrent ketoacidosis. In the 1980s two English and one American group investigated large series of such patients, using new methods to try to uncover a biochemical basis such as defective insulin absorption, accelerated degradation at insulin injection sites, and inappropriate secretion of various counterregulatory hormones. Most of these patients were young overweight women and the eventual conclusion was that in most the instability was self-induced. In the 1980s recurrent, often warningless, hypoglycaemia was recognized as a problem in its own right but in this new generation was reborn as a problem of insulin pharmacokinetics as Woodyatt originally conceived it.
Cell-cell signaling pervades all aspects of development, not just in vertebrates, but in all animals (metazoa). It is a typifying characteristic of the major multicellular life forms, animals, plants, and fungi, which diverged about 1.2 billion years ago from a common ancestor descended from a lineage of unicellular life forms. In metazoa, at least 17 kinds of signal transduction pathways operate, each distinguished by its transduction intermediates. Five kinds predominate in early embryonic development, namely, the Wnt, TGF-beta, Hedgehog, RTK, and Notch pathways. Five more are used in late development, and seven more in the functions of differentiated cells. The pathways must have evolved and become conserved in pre-Cambrian times before the divergence of basal members of most of the modern phyla. In metazoan development and physiology, the responses of cells to intercellular signals include cell proliferation, secretion, motility, and transcription. These responses tend to be conserved among metazoa and shared with unicellular eukaryotes and in some cases even with unicellular prokaryotes. Protein components of the responses date back 2 billion years to ancestral eukaryotes or 3 billion to ancestral prokaryotes. Each metazoan developmental process consists of a network of signals and responses, and many of these networks are conserved among metazoa, for example, by insects and mammals. The study of model organisms, even of nonvertebrate groups, is expected to continue to contribute greatly to the understanding of mammalian development and to offer opportunities to analyze the effects of toxicants on development, as well as opportunities to devise incisive assays for toxicants.
Cell death is a physiological process which is required for normal development and existence of multi-cellular organisms. Physiological cell death, or apoptosis, is controlled by an evolutionarily conserved mechanism. Abnormalities in this process are implicated as a cause or contributing factor in a variety of diseases. Inhibition of apoptosis can promote neoplastic transformation, particularly in combination with dysregulated cell-cycle control, and can influence the response of tumour cells to anti-cancer therapy. Molecular biological and biochemical approaches are used to find missing cell-death regulators and to define signalling cascades, while experiments in genetically modified mice will identify the essential function of these molecules. Discoveries from cell death research should provide clues for designing therapies for a variety of diseases, including degenerative disorders, auto-immunity and cancer.
Optimal application of the nerve conduction study depends on an understanding of the principles and a recognition of the pitfalls of the technique. The conventional methods deal primarily with distal nerve segments in an extremity. Other techniques allow one to assess nerve segments in less accessible anatomical regions, to improve the accuracy in precisely localizing a focal lesion, and to increase sensitivity in detecting subclinical abnormalities. Despite certain limitations, these methods can provide diagnostically pertinent information if they are used judiciously in appropriate clinical contexts. I wish to review the fundamental concepts of nerve stimulation techniques and their proper applications in the clinical domain. The discussion primarily relates to the importance of reproducibility of various measures and pitfalls in the evaluation of conduction block.
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Austin Bradford Hill was once a friend to The Lancet, but, as occasionally happens, friends fall out. The great legacy of his association with the journal, however, was Principles of Medical Statistics. As each edition was succeeded by another--the first in 1937, the last in 1991--he seemed to shift his view about the influence of statistical method on clinical practice from one of assured certainty to one of modest advantage. That change paralleled a move away from an emphasis on the importance of internal validity in the randomized trial to one of understanding the inescapably practical significance of generalizability. Writers on medical research have explored notions of external validity in various ways. One view, for example, is to seek a close correlation between the participants in a clinical trial and patients seen in practice. The argument goes that such a correspondence has to be made before any decision can be taken about whether to apply the result of that trial to the clinical setting. Another view, first worked out by the American logician Charles Sanders Peirce, is that one must simply rely on the informed guess, based on a reasonable estimate of the limits of extrapolation. The tensions between and implications of these two different approaches are worked through using the example of coronary stents. A solution is, perhaps, to write explicit rules of interpretation that provide a framework for judging the strength of a claim to applicability. Five questions are posed, which try to lay a foundation for such a framework.
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Bose-Einstein condensates of dilute gases offer a rich field to study fundamental quantum-mechanical processes, manipulation of the speed at which light propogates, observation of atomic pair-formation and superfluidity, or even simulating white dwarf stars. Still more radical applications are on the horizon. However, their initial creation was a masterpiece of experimental physics. After an initial process of laser cooling (which itself won its developers the 1997 Nobel Prize), atoms in a magnetic-optical trap must be safely transferred into a purely magnetic trap, where the condensation process begins at 170 nK and 20 nK a pure condensate of 2000 atoms could be created. More astonishingly, Wieman and Cornell showed these low temperatures could be achieved in "bench scale" equipment rather than the massive pieces normally demanded by cryoscience. For their 1995 discovery of this new state of matter, they were awarded the 2001 Nobel Prize in Physics.