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Biomedical subjects

H Duncan

Publications and source records attributed to H Duncan.

6 recordsLinked to original sources
PubMed1992

Differential olfactory perception of enantiomeric compounds by blind subterranean mole rats (Spalax ehrenbergi).

The behavior of mole rats (Spalax ehrenbergi) near pairs of enantiomeric compounds was examined in 901 two-choice experimental tests. Positioning of the nest and food store and the preferred location of the tested animal were used to assess attraction or aversion to the tested odorants. The results indicated that mole rats respond differentially to odors of stereoisomers (enantiomers of carvone, citronellol, and fechone). They responded to one enantiomer of each tested pair but were indifferent to or did not smell the other. Both sexes were attracted to the odor of R-(-)-carvone and repelled by the odor of (+)-citronellol. Females were attracted to the odor of (-)-fenchone while males had no preference. By contrast, all animals were indifferent to or did not smell the odor of S-(+)-carvone, (-)-citronellol, and (+)-fenchone. Further research to distinguish between these alternatives (indifference vs hyposmia/anosmia) is suggested.

Acyclic Monoterpenes↗
PubMed1989

Inhibitors of translation induce low density lipoprotein receptor gene expression in human skin fibroblasts.

The effect of protein synthesis inhibitors on low density lipoprotein (LDL) receptor gene expression was examined in human skin fibroblasts. Incubations in cycloheximide led to a marked increase in LDL receptor mRNA abundance as detected by Northern or slot-blot hybridization analyses. Incubation in puromycin had a similar effect. After the addition of cycloheximide, induction of LDL receptor mRNA levels was rapid (peaking between 2 and 3 h) and transient (falling to control levels by 24 h). This incubation could not be accounted for by the modest stabilization of mature LDL receptor mRNA species produced by cycloheximide and was completely abolished by concurrent addition of actinomycin D. Nuclear run-off transcription assays demonstrated increased LDL receptor gene transcription after 20-min incubations in cycloheximide. Induction of LDL receptor mRNA by cycloheximide was partially resistant to sterol suppression and was at least additive with induction produced by growth activation of cells using platelet-derived growth factors. These results indicate that inhibition of protein synthesis leads to rapid stimulation of LDL receptor gene transcription by a mechanism which is partially resistant to sterol suppression. We further conclude that early stimulation of LDL receptor gene expression associated with growth-activation of quiescent cells is independent of new protein synthesis.

Cells, Cultured↗
PubMed1977

Hydrogen peroxide induces spawning in mollusks, with activation of prostaglandin endoperoxide synthetase.

Addition of hydrogen peroxide to seawater causes synchronous spawning in gravid male and female abalones, and certain other mollusks as well. This effect is blocked by exposure of the animals to aspirin, an inhibitor of the enzyme catalyzing oxidative synthesis of prostaglandin endoperoxide. Hydrogen peroxide activates this enzymatic reaction in cell-free extracts prepared from abalone eggs (a very rich source of the prostaglandin endoperoxide synthetase); this effect appears to reveal a fundamental property of prostaglandin endoperoxide synthesis. Applicability of these findings to both mariculture and medical purposes is suggested.

Animals↗
PubMed1975

Synovial fluid analysis.

Synovial fluid analysis plays an important role in the differential diagnosis of various forms of arthritis. The results of macroscopic, biochemical, bacteriological, and microscopic techniques of evaluating synovial fluid must be correlated to establish the diagnosis of each of the various forms of arthritis. The principle of polarized microscopy as applied to the differential diagnosis of crystalline arthritis is currently of special interest.

Adrenal Cortex Hormones↗