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Biomedical subjects

D McCune

Publications and source records attributed to D McCune.

6 recordsLinked to original sources
PubMed1991

Response of photosynthesis and cellular antioxidants to ozone in populus leaves.

Atmospheric ozone causes formation of various highly reactive intermediates (e.g. peroxyl and superoxide radicals, H(2)O(2), etc.) in plant tissues. A plant's productivity in environments with ozone may be related to its ability to scavenge the free radicals formed. The effects of ozone on photosynthesis and some free radical scavengers were measured in the fifth emergent leaf of poplars. Clonal poplars (Populus deltoides x Populus cv caudina) were fumigated with 180 parts per billion ozone for 3 hours. Photosynthesis was measured before, during, and after fumigation. During the first 90 minutes of ozone exposure, photosynthetic rates were unaffected but glutathione levels and superoxide dismutase activity increased. After 90 minutes of ozone exposure, photosynthetic rates began to decline while glutathione and superoxide dismutase continued to increase. Total glutathione (reduced plus oxidized) increased in fumigated leaves throughout the exposure period. The ratio of GSH/GSSG also decreased from 12.8 to 1.2 in ozone exposed trees. Superoxide dismutase levels increased twofold in fumigated plants. After 4 hours of ozone exposure, the photosynthetic rate was approximately half that of controls while glutathione levels and superoxide dismutase activity remained above that of the controls. The elevated antioxidant levels were maintained 21 hours after ozone exposure while photosynthetic rates recovered to about 75% of that of controls. Electron transport and NADPH levels remained unaffected by the treatment. Hence, elevated antioxidant metabolism may protect the photosynthetic apparatus during exposure to ozone.

Journal Article↗
PubMed1990

Reliability of a modification of the health-related physical fitness test for use with physical education majors.

A modified form of the AAHPERD Health-Related Physical Fitness Test was administered to a sample of 200 college physical education majors. The skinfold measures were changed from the original test, and the flexed-arm hang was added to the test battery. The validity and reliability of the test battery has been established for middle school boys and girls. This study determined the multivariate reliability of the modified test battery using a canonical correlation model. The univariate intraclass reliabilities of the test items ranged from .91 to .99. The total redundancy for the modified test battery was .87.

Adult↗