Biomedical subjects
R A Fox
Publications and source records attributed to R A Fox.
A link between helper and suppressor factors and the lymphokines migration inhibition factor and migration stimulation factor.
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Macrophage migration stimulation factor.
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Influence of personal characteristics of the speaker on phonetic quality in perception of vowels.
This study was designed to investigate the effect of speaker's voice quality on perceived phonetic quality in vowels using a perceptual scaling task. 16 subjects scales sets of vowels produced by six different speakers (three women, three men). Analysis indicated no significant influence of speaker's quality on judgments of similarity of vowels. Results suggest that judgments of similarity were made on the basis of linguistically categorized images.
Endotoxin and macrophage-migration inhibition.
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Verification by Monte Carlo methods of a power law tissue-air ratio algorithm for inhomogeneity corrections in photon beam dose calculations.
A Monte Carlo computer program has been used to calculate axial and off-axis depth dose distributions arising from the interaction of an external beam of 60Co radiation with a medium containing inhomogeneities. An approximation for applying the Monte Carlo data to the configuration where the lateral extent of the inhomogeneity is less than the beam area, is also presented. These new Monte Carlo techniques rely on integration over the dose distributions from constituent sub-beams of small area and the accuracy of the method is thus independent of beam size. The power law correction equation (Batho equation) describing the dose distribution in the presence of tissue inhomogeneities is derived in its most general form. By comparison with Monte Carlo reference data, the equation is validated for routine patient dosimetry. It is explained why the Monte Carlo data may be regarded as a fundamental reference point in performing these tests of the extension to the Batho equation. Other analytic correction techniques, e.g. the equivalent radiological path method, are shown to be less accurate. The application of the generalised power law equation in conjunction with CT scanner data is discussed. For ease of presentation, the details of the Monte Carlo techniques and the analytic formula have been separated into appendices.
Practical multiple-choice exams.
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Perturbation of the human immune system by lithium.
The effect of lithium on the human immune system is unknown. We studied lymphocyte responses to mitogens and their ability to produce lymphokines in four patients before and during lithium therapy. We found that with time, lithium increased lymphocyte responses to mitogens (PHA and PWM) and lymphokine production was altered from migration stimulation factor to migration inhibition factor. Although the exact mechanism is unknown, we propose that lithium has an effect on the suppressor cell system.
Macrophage migration stimulation factor, migration inhibition factor and the role of suppressor cells in their production.
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Membrane glycoproteins shed in defence of the cells of the gastrointestinal tract.
The cells lining the gastrointestinal tract are exposed to various potentially harmful agents, including plant lectins and microorganisms. It is proposed that glycoproteins within the mucus layer of the gut protect against these agents. A hypothesis is presented that membrane glycoproteins are shed and, within the mucus close to the cell surface, block the binding of lectins or attachment of microorganisms to membrane receptors. A model is presented that demonstrates that such blocking can be achieved by soluble glycoproteins. The implications of this hypothesis in health and disease are discussed.
Feasibility of absolute activity measurements using the Cleon emission tomography system.
Large volume and small discrete sources of Tc-99m were used to study the spatial resolution, sensitivity, linearity and reproducibility of the radionuclide brain images. The spatial resolution is constant both within and perpendicular to the section. For uniform distributions of activity the response is uniform over the field of view, and the mean pixel count rate is a linear function of the radioactive concentration and is independent of the diameter of the source. However, for discrete sources, the sensitivity was found to vary with the position of the source, and the potential of the system for quantitative assessment of the uptake of radioactivity in organs and tumors was limited initially. Later studies, with modified software, show that this undesirable effect has been reduced.
The dose in water surrounding point isotropic gamma-ray emitters.
A Monte Carlo method has been used to calculate the dose distribution around point gamma-ray emitters in water. Five gamma-ray emitting radionuclide, 60Co, 137Cs, 192Ir, 198Au and 226Ra, which are commonly used in radiotherapy interstitial implants have been considered. The results are in substantial agreement with those derived using a combination of experimental and theoretical data.
Suppression of delayed hypersensitivity by the depletion of circulating monocytes.
The intraperitoneal injection of Marcol oil was previously reported to result in the depletion of circulating monocytes. The way in which this depletion affected guinea-pigs' ability to respond to challenge with antigen was tested by challenging with tuberculin after sensitization and examining the ability to respond to DNCB. It was found that the ability to respond to tuberculin was completely abrogated by the injection of Marcol and could be restored by removing the oil from the peritoneal cavity. The ability to respond to a secondary challenge with DNCB was not affected, while the ability to become sensitized was impaired. A normal inflammatory response was seen. The role of the circulating monocyte is discussed.
Doctors, drink, and disease.
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Models of normal and transformed cell adhesion, and capping and locomotion in vitro.
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Models of cell surface events during normal and transformed human cellular adhesion in vitro.
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The biochemical and biological characterization of macrophage migration inhibition factor isolated from fetal calf serum by affinity chromatography.
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Cellular immunity to a lung homogenate in asymptomatic cigarette smokers.
Leucocyte migration in the presence and absence of a soluble lung homogenate has been studied in a group of asymptomatic cigarette smokers. Results were expressed as migration indices. Controls consisted of age-matched subjects who had never smoked and had no past history of any pulmonary disease. The migration indices, the number of pack-years smoked and the results of pulmonary function studies were tested for correlation. The mean leucocyte migration index of the test group of sixteen smokers was significantly less than was that of the control group (P less than 0.001). Inhibition of leucocyte migration in the presence of the lung homogenate was not observed in any of the control subjects. Six of the sixteen asymptomatic cigarette smokers, however, were identified by inhibition of leucocyte migration in the presence of the lung homogenate. The number of pack-years which had been smoked did not correlate with the migration indices (r = -0.06); however, inhibition of leucocyte migration was not observed in subjects who had smoked less than 6 pack-years.