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J C Riley

Publications and source records attributed to J C Riley.

33 records · Page 2Linked to original sources
PubMed1985

Calcium-regulated plasma membrane rigidification during corpus luteum regression in the rat.

Plasma membrane fractions were prepared from ovaries of superovulated rats and examined for structural changes during luteolysis. Using fluorescence polarization, we observed a rapid rigidification in vitro of samples obtained from ovaries undergoing spontaneous or prostaglandin F2 alpha-induced regression. The rigidification, manifested by a 72% polarization increase over 50 min, is calcium and calmodulin dependent, temperature sensitive and protein mediated. This increase in polarization did not appear in fractions from nonregressing ovaries; however, addition of phospholipase A2 caused virtually identical changes in polarization results as in samples prepared from regressing ovaries. These results suggest that calcium-calmodulin-dependent phospholipase A2 plays a role in membrane deterioration during luteolysis.

Animals↗
PubMed1984

Alterations in the cellular membranes of regressing rat corpora lutea.

Wide angle x-ray diffraction and fluorescence polarization were used to determine the structural properties of membranes from rat luteal cells. Examination of a plasma membrane fraction by x-ray diffraction revealed a significant increase in the gel phase melting temperature during luteal regression. The membrane fluidity of this fraction as well as that of a preparation of microsomes was also studied by fluorescence polarization. Using a fluorescent probe, membrane fluidity was observed to decrease during luteolysis. The temporal correlation between structural changes in the membrane and decreased progesterone secretion suggests that alterations in the physical properties of cellular membranes may be involved in the process of luteal cell regression.

Animals↗
PubMed1983

The effect of prolactin pretreatment on prostaglandin F2 alpha-associated structural changes in membranes from rat corpora lutea.

The ability of prolactin treatment to antagonize the luteolytic effect of prostaglandin F2 alpha (PGF2 alpha) was examined in the rat. Animals were superovulated, treated with PGF2 alpha and various doses of prolactin. Plasma progesterone concentrations were measured to assess luteal function. Microsomes were prepared from ovarian homogenates and examined by wide-angle x-ray diffraction for evidence of structural changes in the cellular membranes during luteolysis. In addition, the concentrations of various lipids were analyzed for alterations in membrane lipid composition. In preparations from control animals, all of the membrane lipid was in the liquid-crystalline phase at body temperature. However, in samples from PGF2 alpha-treated rats, portions of the bilayer underwent a structural alteration from liquid-crystalline to gel phase. This phase transition was not accompanied by significant changes in the relative concentrations of various lipids. Prolactin treatment was effective in inhibiting this membrane breakdown in a dose-dependent manner. These results suggest that PGF2 alpha and prolactin may control luteal function by affecting membrane structure.

Animals↗
PubMed1979

Polycystic renal disease in related cats.

Six kittens from four litters of related cats had greatly enlarged abdomens and died before they were 7 weeks old. Kittens from two litters were necropsied and found to have bilateral polycystic renal disease and cystic bile ducts.

Animals↗
PubMed1975

Endoscopic retrograde choledochopancreatography.

Endoscopic retrograde choledochopancreatography (ERCP) was attempted in 77 patients. Of 33 patients suspected of having bilitary tract disease, ductograms were obtained in 21. Of 56 patients suspected of having pancreatic disease, ductograms were obtained in 35. Since 12 patients were thought to have disease of both ductal systems, the total number of suspected ducts exceeds the number of patients. It is concluded that ERCP is a valuable diagnostic tool in the evaluation of pancreatic or biliary tract disease. Additional data from a prospective study are necessary to determine its clinical relevance.

Amylases↗
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

Changes in the pulse wave form with flow through vessels with repetitive saccular dilatations and stenosis.

Several patients with fibroplasia of the renal arteries without significant stenosis were found to have surgically reversible renal hypertension. The hypothesis is advanced that receptors in the kidney may respond to altered wave form by causing an increase in blood pressure. Various models of normal and pathological renal arteries were made and tested in a pulse duplicator. A discrete harmonic analysis was made of input and output waves. The results indicate that nodular, non-stenotic models significantly alter the systolic rise in perfusion pressures to the kidney. Therefore, irregularity of vessel lumen without stenosis may be sufficient to alter organ function.

Diverticulum↗