Biomedical subjects
G N McEwen
Publications and source records attributed to G N McEwen.
Carmine dye allergy ingredient labeling.
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Evaluation of the cumulative (repeated application) eye irritation and corneal staining potential of FD&C yellow no. 5, FD&C blue no. 1 and FD&C blue no. 1 aluminium lake.
A protocol to evaluate the ocular irritation, staining, and embedding potential of FD&C colours (Yellow No. 5, Blue No. 1, Blue No. 1 Aluminium Lake) produced by repeated topical application to rabbit eyes is described. Test materials (3%, w/v in aqueous vehicle) were administered once daily, for a total of 21 days, to the conjunctival sac of the right eye of New Zealand White Rabbits (6 of each sex per group) at a dose volume of 30 microliters. Control animals (6 of each sex) received 30 microliters of the vehicle daily. All animals survived and were free of significant clinical signs of toxicity throughout the study. Ophthalmoscopic examinations revealed that all animals were free of abnormalities considered to be of clinical importance; all animals were free of significant signs of ocular irritation, staining and particle embedment. The results of this study support the safe use of these materials in consumer products intended for use in the eye area.
The biological interaction of cis- and trans-urocanic acid and DNA.
The potential for the cis and trans isomers of urocanic acid to produce DNA damage was measured by assays for DNA binding (32P-postlabeling assay), for induction of DNA repair (unscheduled DNA synthesis assay) and induction of mutations (Salmonella typhimurium and Escherichia coli plate-incorporation assays). These assays did not detect any evidence of a direct effect of either isomer of urocanic acid on DNA over a wide range of concentrations. These results suggest that neither isomer of urocanic acid alone, nor ultraviolet-irradiation of either cis or trans-urocanic acid produces significant DNA damage under conditions that permit cell survival.
Use of impedance plethysmography to continually monitor bone marrow blood flow.
Methods for measuring bone-blood flow are often time-consuming, tedious, single-point measurements which require sacrifice of the animal. An impedance plethysmographic technique is described which can be used to quantify temporal bone marrow blood flow changes. Results obtained with the impedance technique compare favorably with the data from simultaneously administered microspheres. Injection of sympathomimetic drugs produced measurable responses: isoproterenol caused a significant increase in bone marrow blood flow within 1 min and levarterenol decreased bone marrow blood flow. Data obtained with impedance plethysmography suggest that the technique is feasible for multiple measurements on the same animal and that the technique can be used to study acute or chronic changes in bone marrow blood flow following various experimental treatments.
Behavioral fever in newborn rabbits.
Rabbit pups, 12 to 72 hours old, did not develop a fever when injected intraperitoneally with a pyrogen and maintained at an ambient temperature of 32 degrees C for 2 hours. When placed in a thermally graded alleyway, animals injected with pyrogen selected gradient positions that represented significantly higher temperatures than controls injected with saline (40.4 degrees in contrast to 36.4 degrees C). Allowing the pups to remain at their selected positions for 5 minutes caused a significant increase in the rectal temperatures of the pyrogen-injected pups but not that of the controls. Thus, newborn rabbits will develop a fever by behavioral means after a single injection of an exogenous pyrogen.
A universal bird head-holder for stereotaxic surgery.
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Thermoregulatory responses to preoptic cooling in unrestrained rabbits.
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Resting metabolism and thermoregulation in the unrestrained rabbit.
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No health risk?
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