Biomedical subjects

J C Carlson

Publications and source records attributed to J C Carlson.

57 records · Page 4Linked to original sources

PubMedDate not supplied

Alterations in free radical activity in aging Drosophila.

Drosophila were examined to see if there is an increase in damage associated with free radical activity in older flies. The levels of superoxide radical and of lipid peroxides were higher in membrane samples from older flies. Also, in older Drosophila there was a significant decrease in membrane fluidity, as determined by fluorescence polarization, and an increase in ATP-dependent calcium uptake. In homogenates from whole flies, the concentration of inorganic peroxides and activity of the proteolytic enzyme, cathepsin B, increased with age. During their lifetime, vestigial wing Drosophila displayed a greater level of free radical activity than wild-type flies and a significantly shorter life span (26.7 +/- 0.7 days vs. 34.4 +/- 1.0, p < 0.01). These results indicate that the level of oxidative stress is closely coupled to cellular damage and to life span, and they indicate that free radicals may play a central role in the aging process in Drosophila.

Aging↗

PubMedDate not supplied

A consideration of some notable aging theories.

Aging is characterized as a breakdown process and the relevant events occur after reproduction, when the force of natural selection declines. Studies on the life histories of species reveal that there is an association between resource allocation and longevity and that the aging process is retarded when animals are protected from the deleterious consequences of excess metabolic activity. Although the extent to which aging is caused by environmental or genetic factors is unresolved, our understanding of the field has been enriched by the rapid development of the tools of molecular biology. In his pioneering work, Alex Comfort has postulated a hierarchical clock system as a descriptive paradigm of the aging process, and investigations at the molecular level are bringing to light evidence of a genetic link to life span that seems consistent with Comfort's model. It appears however, that the appropriate context for these mechanistic observations of functional decline is in the postreproductive period.

Aging↗

PubMedDate not supplied

Phenanthrenequinone disrupts progesterone production in rat luteal cells.

The ability of the environmental contaminant phenanthrene (PH) and its photooxidized product phenanthrenequinone (PHQ) to disrupt progesterone secretion was examined in a model system of in vitro suspensions of luteal cells from the rat. Treatment with PHQ dramatically inhibited luteinizing hormone (LH) stimulated progesterone secretion. PHQ also generated a significant increase in reactive oxygen species (ROS). In the absence of LH, however, PHQ stimulated a small increase in basal progesterone secretion. The parent compound, PH, did not alter progesterone or ROS release. Since there is evidence that PHQ lowers the activity of nitric oxide synthase (NOS) and that nitric oxide (NO) affects progesterone production, we examined the response to the NOS inhibitors N-monomethyl-L-arginine, Zn protoporphyrin-9, and aminoguanidine in luteal cells. However, there was no effect of these agents on LH stimulated progesterone secretion. These results indicated that PHQ is a potent disrupter of progesterone secretion and should perhaps be considered in assessing the risk of PH to humans.

Animals↗