Biomedical subjects
Publications and source records attributed to D M Thomas.
Ignition and subsequent combustion of a gum guard, during laser surgery for tracheal stenosis, resulted in a superficial burn to the lower lip. We present a case report and discuss measures that can be taken to avoid such a complication.
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Myofibroblastoma is an uncommon mesenchymal tumour characterized by spindle cells exhibiting the ultrastructural and immunohistochemical features of myofibroblasts. We report a case of a myofibroblastoma occurring in the ethmoid sinus, which to our knowledge is the first case reported in the literature. The clinical presentation, diagnosis, histology, and management of this lesion is discussed with a review of the relevant literature.
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Age deficits in visual search often are attributed to difficulties in comparing display items to target representations. In the presence-absence search paradigm, however, these comparisons are frequently confounded with age differences in the latency and velocity of saccadic eye movements, reductions in the useful field of view (FOV), and retention of information concerning previously searched locations. To circumvent these shortcomings, 20 young and 20 older adults were compared in the speed of their same-different judgments of two perifoveal stimuli. The two stimuli were either identical or varied along one or more of the dimensions of size, shape, and color. In both age groups, RT for correct "different" judgments increased with stimulus similarity, an effect which was more pronounced in the elderly subjects. Results suggest that age differences in free search are due, in part, to an age-related decline in the speed of evaluating object congruence.
Age differences in the useful field of view (UFOV) were examined by asking younger (mean age = 24 years) and older (mean age = 64 years) observers to search for two oriented line targets. These targets were presented at eccentricities ranging from 4 degrees to 14 degrees, and were embedded in either no distractors, homogeneous distractors, or heterogeneous distractors. Eye movements were recorded, along with reaction time (RT) and accuracy. The eye movement data indicated that older observers had more difficulty locating peripheral targets, particularly when they were embedded in heterogeneous distractors. Furthermore, the greater effects of eccentricity and distractor type found in the RT's of older adults were eliminated when age differences in saccade number were partialled out. These findings suggest that age differences in search are largely attributable to factors other than selective attention.
The glomerular permselectivity to polydisperse neutral dextrans was compared in 6 patients with thin membrane nephropathy (TMN) and 10 healthy controls. Despite having normal renal hemodynamics and minimal proteinuria, the patients with TMN had significantly increased fractional clearance of neutral molecules with Stokes radius > 42 A. Conventional theories of glomerular barrier size selectivity cannot fully explain these data since they would predict that our patients would have had nephrotic range proteinuria.
The present studies were undertaken to characterize the properties of a recombinant truncated rat LH/CG (rLH/CG) receptor representing the extracellular domain (rLHR-t338) expressed in mammalian cells. Using detergent-soluble extracts of stably transfected cells, we show that the binding of ovine (o) LH to the extracellular domain is different from the binding of oLH to the full-length receptor. Thus, whereas the full-length receptor from either rat corpora lutea or stably transfected 293 cells binds oLH with two apparent affinities, rLHR-t338 binds oLH with only one affinity, which is intermediate between the high and low affinities of the full-length receptors. However, rLHR-t338 as well as the full-length receptor binds hCG and hLH with similar high affinities and by a model assuming the presence of only one binding site. These data are consistent with the possibility that the carboxyl-terminal half of the LH/CG receptor may contribute (either directly or indirectly) to a second low affinity hormone-binding site. The truncated receptor retains normal binding specificity, as it does not bind hFSH, demonstrating that the extracellular domain alone contains all of the necessary elements for conferring specificity among the gonadotropin hormones. Our studies also show that rLHR-t338 is glycosylated and migrates as two proteins of 48 and 44 kilodaltons (kDa) on sodium dodecyl sulfate gels (where the 44-kDa species is probably a partially degraded form of the 48-kDa protein). However, the N-linked oligosaccharides of the truncated receptor do not appear to be fully processed, as they remain in a high mannose form. rLHR-t338 is not secreted from cells, but remains trapped intracellularly. It can be detected, though, in detergent-soluble extracts of cells or in homogenates. Upon centrifugation of homogenates, it was found that about 90% of the recoverable truncated receptor can be obtained in the supernatant fraction. Thus, mammalian cells could provide a source of a water-soluble extracellular domain of the LH/CG receptor.
Mononuclear leukocytes preferentially accumulate in the central nervous system (CNS) during the course of experimental autoimmune encephalomyelitis (EAE). To address factors that govern leukocyte trafficking in EAE, we monitored expression of mRNAs encoding IP-10 and JE/MCP-1, which are members of a family of chemoattractant cytokines. A transient burst of IP-10 and JE/MCP-1 mRNA accumulation in the CNS occurred, in close relation to the onset of histologic and clinical disease. In situ hybridizations showed, unexpectedly, that astrocytes were the major source of mRNAs encoding IP-10 and JE/MCP-1. These observations implicate astrocyte-derived cytokines as potential chemoattractants for inflammatory cells during EAE.
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In a series of 31P NMR experiments the effects of near-UV radiation on the phosphorus metabolites in pigmented lenses from grey squirrels were studied; UV radiation ranged from 300 to 400 nm, peaking at 365 nm. Squirrels were killed, intact lenses removed, exposed to UV, put in an NMR perfusion cell, and 31P NMR spectra were recorded. In vitro exposure of squirrel lenses for periods ranging from 4 to 22 hr were made. ATP levels, as measured by NMR, decreased as the radiation dose increased. For a 22-hr exposure (121 J cm-2) ATP levels decreased by 67% relative to control values. At lower dose levels there was a correspondingly smaller decrease in ATP levels. Histological examination showed UV-irradiated lenses had disrupted epithelium, loss of attachment to cortical fiber cells and fluid accumulation under the capsule. It is clear that lenticular exposure to near-UV, predominantly at 365 nm (UV-A), does cause metabolic deterioration through degradation of normal ATP energy levels. The grey squirrel pigmented lens strongly absorbs near-UV radiation which enhances the observed metabolic changes and observed opacities. The results demonstrate the utility of using 31P NMR to evaluate metabolic changes associated with near-UV irradiation.
The authors present an unusual case of upper airway obstruction due to the presence of bilateral communicating laryngoceles. The use of aspiration techniques on the larger of the laryngoceles resulted in a significant improvement in upper airway function. This improvement avoided the need for a tracheostomy or intubation under potentially hazardous circumstances and allowed the eventual surgery to take place in more controlled conditions.
A 49-year-old man developed acute renal failure as a complication of non-fulminant hepatitis A. This is a rare association of uncertain etiology.
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BACKGROUND: Langerhans cell histiocytosis (LCH) is a reactive disease in which abnormal Langerhans cells accumulate in various body sites and cause damage to affected organs. Adults often do not respond to conventional therapy with local or systemic steroids. OBJECTIVE: Our purpose was to investigate intravenous etoposide as monotherapy in the treatment of adult patients with severe or resistant LCH. METHODS: In an open study, three adult patients with LCH (one with single-system skin disease and two with multisystem disease) were treated with etoposide, 100 mg/m2/day, for 3 days. This was repeated every 3 or 4 weeks for three or four cycles. RESULTS: All patients achieved clinical remission that persisted during a 12- to 14-month follow-up. No serious side effects were noted. CONCLUSION: We recommend the use of etoposide monotherapy in severe or restricted LCH in adults.
Twelve patients with active duodenal ulcer disease and Helicobacter pylori infection were treated with 1 g sucralfate q.d.s. for 1 month. Ulcers healed in 8 of the 12 patients without an alteration in the H. pylori-associated antral gastritis. Sucralfate produced a significant fall in basal acid output in all the patients, from a median of 4.8 (range 2.1-12.1) to 1.6 (0.4-8) mmol/h, P less than 0.01, whereas peak acid output was unchanged from 41 (21-59) before to 38 (24-55) mmol/h after treatment. Basal plasma gastrin concentrations and the meal-stimulated integrated gastrin response were not altered significantly by sucralfate: 8 (2-17) pmol/L and 732 (188-1045) pmol. min/L pre-treatment and 6 (2-17) pmol/L and 600 (140-1302) pmol. min/L post-treatment, respectively. The fall in basal acid output observed may contribute to prolonged duodenal ulcer remission after treatment with sucralfate.
The p53 tumour suppressor gene has been shown to be frequently mutated in a wide range of human neoplasms. This is accompanied by increased levels of p53 protein which become immunologically detectable in pathological material. We have investigated the possibility that the differential diagnosis between reactive and neoplastic mesothelium might be resolved using a polyclonal serum raised to human p53 protein, CM-1. None of 20 cases of reactive mesothelial proliferation showed p53 immunoreactivity while 70% (14 of 20) of cases of malignant mesothelioma showed p53 staining. We can thus infer that abnormalities of p53 appear to be a common event in malignant mesothelioma and that p53 immunostaining may be of value in the distinction of malignant mesothelioma from reactive hyperplasia.