Biomedical subjects
Publications and source records attributed to V C Smith.
A simple, safe method for creating a long term jejunal feeding route using the standard Hickman catheter is described herein. The positive results in pediatric patients suggest that this method would be suitable in selected adult instances.
Error scores on the Farnsworth-Munsell 100-hue test were partitioned into those representing red-green and those representing blue-yellow losses. Data from two groups of normal observers were used. One group showed results characteristic of published norms; one group showed superior performance. Both observers showed a correlation between red-green and blue-yellow scores indicative of a strong performance factor in this test. The difference between blue-yellow and red-green scores eliminates their correlated variance and allows evaluation of the axis. Both groups showed an increase in difference scores, with age indicating development of a blue-yellow axis. This increase was significant for the observers characteristic of the norms. We suggest cutoff scores to allow a decision as to whether a given patient shows a blue-yellow or red-green axis.
Primary splenic angiosarcomas are rare neoplasms. The diagnosis can only be made at surgery. Splenectomy prior to rupture prolongs survival. An unusual case report is presented and the literature reviewed.
The relative contributions of chromatic and achromatic activity to reaction time were investigated under conditions in which spatial and temporal transients were manipulated. Simple reaction times (RT) were obtained to eight photometrically matched (1 cd/m2) wavelengths between 448 and 658 nm. These stimuli were incrementally presented on a spatially coextensive 1.2 degrees white adapting field. RT was wavelength dependent for 5 or 10 cd/m2 steady backgrounds or a 5 Hz 1.2 cd/m2 flickering background. RT varied as a trichromatic saturation-like function (slowest RT at 572 nm). In comparison, RT was wavelength independent when no adapting field was present and when the 1.2 cd/m2 field was flickered at 15 Hz.
We evaluated foveal cone photopigment kinetics by retinal densitometry in 14 patients (12 men and two women, ranging in age from 30 to 54 years) with central serous choroidopathy. At the initial examinations when 12 of the 14 patients showed active leaks, the measured two-way density of pigment was low and the time-course of regeneration was slow. At later examinations, we found low two-way densities with normal regeneration times in five patients without active leakage. Near normal two-way densities occurred only in three patients who had complete clinical recoveries.
We compared unique and other constant hue loci measured at a fixed retinal illuminance for the same observers. When expressed in Judd chromaticity coordinates, unique hue and constant hue data agreed. Unique blue loci were curved, and unique red and green loci were noncollinear. These data imply that unique hues are not a linear transformation of color matching functions. Linear models are only an approximation, even at a single luminance level.
We measured colorimetric purity thresholds as a function of stimulus duration for seven wavelengths between 430 and 650 nm. Purity thresholds were measured in a hue substitution mode. The purity-duration function showed decreasing purity as duration was increased to about 640 msec. Functions for different wavelengths could be fit by a fixed chromatic template displaced on the purity axis. Increment thresholds as a function of duration were measured for white and chromatic lights added to a homogeneous white stimulus field. The "white" function showed no integration beyond 160 msec and was fit by an achromatic template. The wavelength functions were not parallel; wavelengths at the spectral extremes showed longer integration times, similar to the purity-duration functions. Increment data could be fit by a vector sum of chromatic and achromatic templates.
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We measured the radiance response function for steady state bleaching lights and the regeneration of the cone visual photopigments using the continuous recording densitometer described by v. Norren and v.d. Kraats. Measurements made on 5 deuteranopes, 1 protanope and 2 color-normal observers were similar. The radiance response function was steeper than the function predicted by a simple first-order kinetic equation. For a measured density (ca 0.3) we evaluated whether high stray light (ca 47.5%) and high two-way optical density (ca 1.3) could account for the deviation from the prediction of a first-order equation. Such a model was rejected because these parameters predicted different estimates of the time course of regeneration for different test wavelengths (554 and 605 nm). Statistical analysis of the regeneration data revealed a highly significant non-linearity. A model in which the rate of regeneration increases as the proportion of bleached photopigment decreases is required to explain both the radiance function and the regeneration data.
The purpose of this study was to determine the immediate and long-term complications of subclavian vein thrombosis occurring during prolonged catheterization for parenteral nutrition. Ten cases of subclavian vein thrombosis documented by venography were initially treated by catheter removal, systemic heparin, and upper extremity elevation. Although fever was common (N = 9), only three patients had positive blood or catheter cultures and only one patient required antibiotic therapy. Nonfatal pulmonary embolism was suspected by lung scan in only one patient. After a follow-up period of six months to five years (mean two years), no long-term disability, such as arm swelling or pain, was identified. We conclude that immediate and late sequelae of catheter-associated subclavian vein thrombosis are minimized by prompt removal of the catheter, systemic administration of heparin to prevent clot propagation and embolism, and arm elevation to reduce early upper extremity edema.
Five affected males in the fifth generation of a large pedigree of X-chromosomal incomplete achromatopsia were tested. All had SWS cone function. A 19-year-old affected man was a classical blue cone monochromat on color matching and spectral sensitivity. A 16-year-old boy showed evidence of a long wavelength sensitive cone active in 8 degrees color matches. With a blue-green background, his cone spectral sensitivity function peaked near 550-560 nm. Three younger boys, aged 7-10 yrs were evaluated only with color matching. All showed evidence of long wavelength cone function with an 8 degree field and one showed long wavelength cones in 2 degree matches. An independent observation concerning the family was the finding that deuteranomaly was introduced in the third generation. The fourth generation women, all obligate carriers of X-linked achromatopsia, had a 0.5 chance to carry deuteranomaly. Neither carrier state per se is usually associated with expression of deuteranomaly. Three of the five tested expressed deuteranomaly. This finding of deuteranomaly in the carrier females might be a consequence of a double carrier state indicating association between the genes for deuteranomaly and X-linked achromatopsia.
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We studied color vision in 32 patients with autosomal recessive achromatopsia. Color matching revealed complete achromatopsia (rod monochromasy) in ten patients (Group I) and incomplete achromatopsia in the remaining twenty-two patients. Amongst the incomplete achromats, were three groups distinguishable by their color matching. Patients in Group II were dichromats; their color matches were mediated by rods and MWS (middle-wavelength sensitive) cones. Patients in Groups III and IV were trichromats. Color matches of patients in Group III were mediated by rods, LWS (long-wavelength sensitive) cones and MWS cones. Group III patients showed no evidence of SWS (short-wavelength sensitive) cones. Color matches of patients in Group IV were mediated by rods, LWS cones and SWS cones; color matching did not reveal MWS cones.
The brightness of lights defined by heterochromatic flicker photometry as being of equal luminance was determined by direct comparison with a white standard. Stimuli included mixtures of white and colored lights. Eight different colorimetric purities were tested for each of eleven primaries. Adaptation to a known white was maintained. Resulting brightnesses were expressed in terms of the ratio of the amount of light required for a brightness match to the amount required for a flicker photometric match (B:F). B:F ratios varied with the primary, being largest for red and blue primaries. The variation of B:F ratio with colorimetric purity differed depending on the primary, although for any given dominant wavelength the highest-purity stimulus always had the largest B:F ratio. The data qualitatively exclude a number of simple models of brightness generation.
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A 13-year-old boy with fundus flavimaculatus had a macular disease consisting of many transparent cystoid spaces which were not hyperfluorescent on fluorescein angiography. The Stiles-Crawford effect was abnormal, suggesting that the cystoid changes in the maculas created a disorientation of the patient's foveal retinal photoreceptors.
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