Biomedical subjects
Publications and source records attributed to S J Gibbs.
A patient with a seminoma, squamous cell carcinomas of the skin and anus, Bowen's disease and lymphopenia is reported. The underlying aetiology is thought to be impaired cell mediated immunity and susceptibility to viral infections.
OBJECTIVE: Our primary objective was to determine the frequency of disk reduction after modified condylotomy and whether the type of displacement affected outcome. DESIGN: We classified reducing disk displacements from magnetic resonance images of 80 symptomatic temporomandibular joints before modified condylotomy. Disk position was reassessed after surgery. RESULTS: The disk and condyle typically move in reciprocal directions. The disk was reduced by surgery in 79% of the joints. The rate of reduction varied by the type of displacement, but the differences between the groups were not statistically significant. CONCLUSION: This finding reaffirms that modified condylotomy has a high rate of disk reduction. The unexpected observation that the increase in joint space resulting from the surgery typically permitted a variable degree of spontaneous movement of the disk has implications for the nature of osteoarthrosis and internal derangement and for surgical treatments intended to reduce the risk.
Chronic alcohol-dependent patients have reduced brain volumes and concomitant neurobehavioral deficits that may recover during abstinence. In 10 chronic alcoholic patients, using localized proton magnetic resonance spectroscopy, we found reliable increases during the first 3-4 weeks of abstinence in the concentrations within the superior cerebellar vermis of choline (Cho)-containing compounds relative to the neuronal marker, N-acetylaspartate (NAA). Lesser changes were observed following 1 month of abstinence, and in one of the patients studied longitudinally over 3 months, a marked reduction in the Cho/NAA ratio was associated with relapse. After detoxification, the Cho/NAA ratio correlated with a composite clinical impression of brain functions. The lowest Cho/NAA was observed in a patient with persisting alcoholic dementia, in striking contrast to reduced relative concentrations of NAA reported in dementia of the Alzheimer's type. Possible molecular explanations for these brain metabolic changes are discussed.
Explosive growth in high-technology imaging continues in dentistry as in all health sciences. Some new technology will find its way into general and some specialty dental practices; two examples, digital intraoral radiography and multimodality panoramic machines, are reviewed. New developments in the application of current imaging procedures (both conventional and "high tech") to diagnosis and management of diseases and injuries of the jaws, muscles of mastication, and salivary glands are presented. Recent information suggests that the risk of radiation-induced cancer in exposed populations may be greater than had been recognized. The impact of this data on both occupational and patient radiation exposure in dentistry is reviewed.
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Installation of a radiology information management system (RIS) is usually justified on the basis of improved departmental efficiency and improved charge capture. However, evaluation of the success of these expected improvements is often difficult. The installation and operation of such a system in a medium-sized tertiary care hospital has permitted the effects of the RIS on the operation of the department to be studied and the improvements in charge capture provided by the system to be quantitatively assessed. As a result of a side-by-side comparison with a conventional check-sheet manual billing system, it is apparent that the RIS reduces the errors inherent in manual systems. Subjectively, it is also apparent that personnel prefer the computerized system to the manual charge sheets.
Magnetic resonance (MR) imaging and phosphorus-31 MR spectroscopy were used to examine four patients with dermatomyositis and five control subjects. T2-weighted images of the thigh muscles of patients showed increased signal intensity, with focal and inhomogeneous involvement predominantly in the vastus lateralis and secondarily in the vastus intermedius and vastus medialis. T1 and T2 values of the vastus lateralis in patients were significantly higher than those of the control subjects. T1 values of the rectus femoris and biceps femoris with more generalized inflammation were moderately elevated but still significantly higher than those of the control subjects. P-31 MR spectra of the quadriceps muscles were obtained during rest, during exercise at two graded levels, and in recovery. Concentrations of adenosine triphosphate and phosphocreatine (PCr) in the diseased muscles were 30% below normal values, and the inorganic phosphate/PCr ratios were increased in the patients' muscles at rest and throughout exercise. The T1 and T2 values as well as the P-31 metabolite data correlated with symptoms and clinical assessment.
The ICRP effective dose equivalent has been compared with a weighted dose equivalent, computed by treating the entire remainder instead of the sample of five remainder organs in the ICRP method as uniformly radiosensitive, for dose distributions from three common diagnostic exposures: chest, dental full-mouth and dental panoramic. Complete dose distributions were computed by a Monte Carlo model. In all three cases the effective dose equivalent was greater than the weighted dose equivalent. The difference was only 20% for the chest exam but was more than fivefold for both dental exposures. Dose distributions for the dental exposures were less homogeneous than for the chest examination. Selection of organs to be included in the remainder markedly affects the effective dose equivalent. In the case of highly inhomogeneous dose distributions, the effective dose equivalent probably significantly over-estimates radiation detriment.
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Eight compounds were examined to determine their relative efficacy as antidotes in acute gold intoxication in mice after the intraperitoneal injection of 200 mg/kg of Na3 [Au(S2O3)2] X 2H2O. Of the compounds examined, 2,3 dimercaptosuccinic acid was the most effective antidote. It was noted that with D-penicillamine those animals which did not survive died sooner (in a matter of hours) than the corresponding control animals which had received no antidote (about 3 days). In subsequent experiments in which Na3 [Au(S2O3)2] X 2H2O was administered at the lower level of 140 mg/kg, 2,3 dimercaptosuccinic acid showed itself to be capable of reducing kidney gold levels by a factor of about 5 and liver gold levels by a factor of approximately 2.
Computer simulation methods for determining patient dose from dental radiography have demonstrated that patient risk from a two-film interproximal examination ranges from 1.1 X 10(-8) to 3.4 X 10(-7) using 90-kVp beams, depending on film speed, projection technique, and age and sex of the patient. Further, changing from a short-cone round-beam to a long-cone technique with rectangular collimation reduces risk by a factor of 2.9, independent of other factors.
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Two paramagnetic chelates, chromium EDTA and gadolinium DTPA, were evaluated as potential intravenous contrast agents for magnetic resonance imaging (MR) using a 0.5-T superconducting scanner. After evaluating both agents in vitro, in vivo studies were conducted in dogs to document changes in renal appearance produced by contrast injection. Acute splenic and renal infarction were diagnosed with contrast-enhanced MR and confirmed by gamma camera imaging following administration of Tc-99m-labeled DMSA and sulfur colloid. The authors conclude that intravenous paramagnetic contrast agents presently offer the best mechanism for assessment of tissue function and changes in perfusion with MR.
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Ethylenediaminetetra(methylenephosphonic) acid (EDTPO), when administered as its calcium salt, is an effective antidote for acute intoxication by a number of metal ions. Significant antidotal action was found for the following cations: Cd2+, Ni2+, Zn2+, Pb2+, Be2+ and UO2+(2). Because EDTPO is capable of chelating more than one calcium ion, better results were obtained when the Ca2EDTPO complex was administered.