Biomedical subjects
Publications and source records attributed to J C Townsend.
Meticulous comparison of optic nervehead size has revealed detectable differences in as many as 10% of patients. In many cases the larger nervehead has a larger cup. This may result in the false impression of glaucoma and may be the most common cause of asymmetric cupping in the absence of active, progressive disease. Two cases demonstrating this finding are reviewed with a discussion of its detection and diagnosis.
A patient presented with a pigmented mobile vitreous cyst in the right eye. The cyst was 6-7 mm in diameter, and was free-floating in the inferior half of the vitreous with no apparent attachments. No other ocular pathology was present in either eye. The patient became symptomatic only when the cyst obscured the visual axis. The literature was reviewed and will be discussed in this report.
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I describe a competitive immunoenzymometric assay for urinary albumin, with use of an immobilized albumin-thyroglobulin conjugate and an affinity-purified antibody. The assay is rapid, easy to perform, has a range of 0.5 to 78 mg/L, and is ideally suited for screening purposes. Higher concentrations may be assayed by further dilution of the urine sample. Results compare favorably with those of a commercially available radioimmunoassay kit.
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Retinal lesions resembling retinitis pigmentosa were observed in a 39-year-old white male patient with a history of head trauma, reduced night vision, and periodic perception of light flashes. Perimetric testing revealed contracted superior-temporal fields. The results of numerous other tests of visual function, however, failed to support the tentative funduscopic diagnosis of sector retinitis pigmentosa.
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To determine whether paternal exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) or other polychlorinated dioxins might be associated with adverse pregnancy outcomes, an interviewer-administered questionnaire survey was conducted among wives of Dow Michigan Division employees in the Midland, Michigan, area who had been potentially exposed to dioxins. A control group consisted of wives of employees who had no dioxins exposure and whose hire dates were comparable to those of the men in the exposed group. A total of 737 conceptions, which resulted in 637 live births and 10 stillbirths and spontaneous abortions, were identified as having paternal exposure; 2031 conceptions, resulting in 1785 live births and 246 stillbirths and spontaneous abortions, were identified as having no paternal exposure to any isomer of dioxin. Odds ratios were calculated for dependent variables consisting of spontaneous abortions, stillbirths, infant deaths and several categories of congenital malformations. Trend analysis was performed for duration-of-paternal-exposure of 12 months or less, or more than 12 months. Overall, no statistically significant associations were found between any exposure and pregnancy outcome, either before or after stratification by pertinent sets of up to nine covariables.
Using only a few tests, it was possible to differentially diagnose a benign choroidal nevus with overlying medullation. Having revealed a flat retina with no apparent mass in the area, the ultrasound B-scan initially ruled out a choroidal malignant melanoma, choroidal hemangioma, metastatic tumor and a rhegmatogenous retinal detachment. Binocular indirect ophthalmoscopy and application of the Goldmann 3-mirror gonioscopy lens revealed that the lesion was not a retinal detachment. Due to the location of the lesion, disciform macular degeneration was also ruled out. Fluorescein angiography was the final test which aided in the definitive differential diagnosis, since it was characteristic of a choroidal nevus. Even though not all possible choroidal nevi need such an extensive work-up, occasionally specialized test can aid in the differential diagnosis of benign from potentially malignant lesions.
This study describes the mortality experience of a cohort of 61 males involved in a 1964 chloracne incident. Presumably as a result of skin absorption of the process contaminant, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD or dioxin), 49 of these trichlorophenol production workers developed the skin condition. Within the limitations posed by cohort size and length of follow-up, TCDD does not appear to have adversely affected mortality experience. Overall, four deaths occurred and 7.8 were expected. Of these, one death was due to cardiovascular disease (3.8 expected) and three deaths were attributed to cancer (1.6 expected). None of the findings were statistically significant at alpha = 0.05. Further follow-up is contemplated.
The agriculturally important nematocide 1,2-dibromo-3-chloropropane (DBCP) has been implicated as a cause of human male sterility. A survey at the Michigan Division of The Dow Chemical Company included measurements of semen samples, testicular size, and serum follicle-stimulating hormone (FSH), luteinizing hormone (LH), and testosterone in 232 chemical workers with past potential exposures to DBCP and in 97 nonexposed comparison employees. Potentially exposed groups showed significantly higher, although not abnormal, mean levels of FSH and LH. In the subgroup with the highest potential exposure ending subsequent to 1972, greater duration of exposure correlated with lower sperm count, higher FSH level, and smaller testicular volume. Mean values for this latter time-divided subgroup were not abnormal. The findings are consistent with a testicular effect of DBCP and also with reversibility of that effect over time.
All ten employees have a history of exposure to benzene which exceeded a 25 ppm, eight-hour TWA for several years. For five of these employees this exposure level started over 20 years ago. One employee's high exposure level started over 35 years ago. All ten employees had their initial high exposure to benzene more than 16 years ago. At one period (late 1963 and early 1964) all ten employees had alterations in their peripheral blood studies, evidenced by an increase in MCV. Some of the employees had slight reduction of hemoglobin levels. No other significant blood or bone marrow abnormalities were evident. A mortality study, for the years 1940 to 1973, of 594 employees chronically exposed to benzene at the Midland, Mich., Dow location has recently been accepted for publication. This study was followed by a morbidity study of 282 employees, which were a subset of the employees in the mortality study. The morbidity study was based on health data obtained between 1967 and 1974. The ten employees described in this article were included in both the mortality study population of 594 employees and the morbidity study of the 282 employees.
We previously conducted a cohort mortality study of 594 individuals occupationally exposed to measured concentrations of benzene. This report presents health examination findings for a subset of 282 men from the larger group. Although slight decreases in mean total bilirubin and RBC values were detected statistically in comparing the exposed group to controls, these changes were not regarded as clinically significant. No correlations were found between peripheral blood counts and latency, duration or intensity of benzene exposure. Presently we have no indication from our data of adverse effects of benzene having occurred in our subset. Variation in latency among individuals and the possibility of subtle changes effecting an eventual pattern contribute to the need for continued surveillance.
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