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Biomedical subjects

V White

Publications and source records attributed to V White.

66 records · Page 4Linked to original sources
PubMed1987

Orbital lymphoproliferative and inflammatory lesions.

We reviewed the records and biopsy specimens of 38 patients with clinically similar orbital lymphoproliferative and low-grade inflammatory lesions referred to one ophthalmologist at the University of British Columbia between 1977 and 1984. Twenty-six patients had lymphoproliferative lesions, the main feature being a densely cellular population of small lymphocytes. This group was further divided into reactive lymphoid hyperplasia, malignant lymphoma, Hodgkin's disease and atypical lymphoid hyperplasia. Symptoms and signs were similar within the subgroups. The mean length of follow-up was 3.7 years. Of the 26 patients 14 had extraorbital lymphoproliferative disease, 9 had orbital recurrences and 2 died of widespread disease. Twelve patients had inflammatory lesions with distinctly different histologic features from those of the lymphoproliferative group. Symptoms and signs were similar to those in the latter group. The mean length of follow-up was 2.1 years. Four of the 12 had orbital recurrences; none had extraorbital disease or died of their disease. We feel that orbital lymphoproliferative lesions can easily be separated from clinically similar low-grade inflammatory lesions histologically and that they should be staged and followed like small lymphocytic lymphomas. Guidelines are given for handling these specimens in the laboratory.

Adult↗
PubMed1984

Malakoplakia mimicking carcinoma metastatic to lung.

Malakoplakia is a rare inflammatory disorder which infrequently involves sites outside of the lower genitourinary or gastrointestinal tract. We report a case of malakoplakia in which the patient presented with a left renal mass and bilateral pulmonary nodules suggestive of metastatic renal carcinoma. Postmortem cultures of the lesions grew E. coli; macrophages at both sites contained gram-negative bacilli and numerous Michaelis-Gutmann bodies. X-ray spectroscopic analysis of the bodies showed wide variation in calcium, phosphorus, and iron content, suggesting that Michaelis-Gutmann bodies were formed in part by the deposition of amorphous salts.

Diagnosis, Differential↗
PubMed1981

Occupational asthma in a factory making flux-cored solder containing colophony.

The prevalence of work-related wheeze and breathlessness was measured in factory employees manufacturing flux-cored solder. The flux contained colophony which was heated in the production process, exposing the workers to colophony fumes. Measurement of colophony in the breathing zone defined three grades of exposure with median levels of 1.92 mg/m3 (six subjects), 0.02 mg/m3 (14 subjects), and less than 0.01 mg/m3 (68 subjects). All but two workers in the first two groups, and 90% of a random sample of the last group, were studied. Occupational asthma was present in 21% of the higher two exposure groups and 4% of the lowest exposure group. Mean values of FEV1 and FVC fell with increasing exposure. The prevalence of upper and lower respiratory symptoms was only one-third to a half that found in a previous study of shop floor electronics workers, whose work raised the flux to a higher temperature and produced higher concentrations of colophony fume. Total IgM levels were higher in the solder manufacturers than in unexposed controls, and were higher still in the electronics workers. The solder manufacturers were exposed to colophony fumes at 140 degrees C, below the temperature at which the resin acids decompose, supporting the hypothesis that it is the whole resin acids rather than decomposition products which cause occupational asthma. The threshold limit value should be based on the resin acid content of the fume, and not the aldehyde content as at present. The survey suggests that sensitisation will not be prevented unless exposure is kept well below the present threshold limit value.

Adult↗
PubMed1979

The initiation of gait.

The initiation of gait was studied utilizing electromyography, force-plate data, measurements of walking velocities, and ranges of motion of joints, all of which demonstrated that gait is initiated by the body becoming unbalanced in such a way as to permit a subject to pick one foot the ground in order to take the first step. The subsequent transition of the body to the steady gait pattern occurs rapidly over a period of appproximately three steps. This transition involves rapid changes in the measured forces and activities of the muscles of the lower extremity and the motion of the joints reflects these changes.

Adult↗
PubMed1976

Distribution of tetrahydrouridine in experimental animals.

2-14C-tetrahydrouridine was prepared and used to determine the serum levels and excretion of tetrahydrouridine by varous experimental animals. In mice injected ip with the agent (50 mg/kg), the serum level of tetrahydrouridine was maximum (76 mug/ml) at 15 minutes. For rats injected with the same dose, the tetrahydrouridine content of serum was greatest (58 mug/ml) at 30 minutes. Within 3 hours, the serum content of the drug in both mice and rats fell to less than 10% of the maximum. The kidneys of mice selectively accumulated tetrahydrouridine; the concentration rose to 275 mug/g at 1 hour after injection. Nearly all of the dose was excreted unchanged in the urine of mice and rats in 24 hours. For a dog and a monkey given an iv dose (50 mg/kg) of tetrahydrouridine, serum levels of the agent were 210 and 200 mug/ml, respectively, at 5 minutes. The apparent half-lives for the initial phase of disappearance were 18 and 20 minutes and those for the later phase were 65 and 70 minutes, respectively. In 24 hours the dog and monkey excreted most of the dose as unchanged tetrahydrouridine. No metabolites were detected in the biologic samples from either species.

Animals↗
PubMedDate not supplied

The identification and quantitation of triamterene in blood and urine from a fatal aircraft accident victim.

Triamterene, a diuretic drug used in combination with other drugs for the treatment of hypertension, was found in the blood and urine of a fatal aircraft accident victim. The extraction and identification of triamterene is difficult. It exhibits poor extraction efficiency using some standard base-extraction procedures, and the parent drug is unsuitable for analysis using gas chromatography. In this case, a thin-layer chromatography solvent system and high-performance liquid chromatography were used to identify and quantitate triamterene in blood and urine. Triamterene is a strong absorber in the ultraviolet region and has an unusual UV spectrum, which simplifies the identification and quantitation of this substance by high-performance liquid chromatography.

Accidents, Aviation↗
PubMedDate not supplied

The plasticity of compensatory eye movements in rotatory tests. I. The effect of alertness and eye closure.

Fifteen voluntary subjects with a mean age of 26 years (17-39), participated in two rotatory experiments. The rotatory test used was sinusoidal harmonic acceleration (SHA) test at frequencies of 0.01-0.32 Hz. Compensatory eye movements were measured by means of EOG. Experiment A included rotation in darkness during alerting tasks (day 1), rotation in darkness with no tasks (day 2) and rotation in darkness during alerting tasks (day 3). In the alertness tests, the gain varied between 0.5 and 0.77. Phase values decreased with increasing frequency. The alertness results between days 1 and 3 did not differ in gain or phase. The gain of day 2 (no tasks) displayed significantly reduced gain at all frequencies, and a more pronounced decrease in phase than in the alertness tests. Experiment B comprised testing with eyes open (day 1) and eyes closed (day 2) during alerting tasks. These tests displayed significantly decreased gain at all frequencies with eyes closed compared with eyes open and with more negative phase at 0.08-0.32 Hz with eyes closed. The results indicate a central effect of the alertness level on compensatory eye movements, and the effect of eye closure might be explained by bio-mechanical and possibly even central effects on the eye movements. In low-frequency testing, as short a test time as possible should be used, and due to different alertness levels, the results should be evaluated with great caution.

Acceleration↗
PubMedDate not supplied

Plasticity of compensatory eye movements in rotatory tests. II. The effect of voluntary, visual, imaginary, auditory and proprioceptive mechanisms.

Two groups of 10 healthy volunteers each with a mean age of 28 years (17-39) were tested in low-frequency rotatory experiments (sinusoidal harmonic acceleration, SHA), at frequencies of 0.01-0.32 Hz. The purpose was to ascertain whether voluntary enhancement and reduction of gain and phase occurred with voluntary performances. The different tests were alertness in darkness, stationary and moving targets, imaginary stationary and moving targets in darkness, proprioceptive moving targets and acoustic stationary and moving targets. Alertness tests in darkness demonstrated a gain increase (0.5-0.7) at 0.01-0.32 Hz, and a decreasing phase lead (40-2 degrees) with increasing frequency. The alertness tests served as a reference for the other tests. In tests with stationary targets, the gain reached unity and the phase was almost 0 degrees. In imaginary stationary target tests, gain and phase were significantly increased compared with alertness. Stationary acoustic targets in darkness significantly enhanced the gain. An increased phase lead was also found. In visual suppression tests (moving target), the gain was near 0. In imaginary moving target tests, the gain decreased significantly. In darkness the gain was significantly more depressed with a proprioceptive moving target than during imaginary moving target. Testing with proprioceptive + acoustic moving target in darkness, displayed an additional gain depression and negative phase at 0.08 Hz. The conclusion is that the influence of non-vestibular mechanisms substantially affects low frequency sinusoidal rotatory testing.

Acoustic Stimulation↗