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Biomedical subjects

R G Foster

Publications and source records attributed to R G Foster.

82 records · Page 5Linked to original sources
PubMed1985

Opsin-like immunoreaction in the retinae and pineal organs of four mammalian species.

Opsin-like immunoreactivity was observed in the retinae and pineal organs of the mouse, rat and guinea pig, and the pineal organ of the cat. In the retina the immunoreaction was restricted to photoreceptor cells, which displayed immunostaining in their perikarya and outer and inner segments. Distinct pinealocytes endowed with characteristic processes were labelled in the pineal organs of the mouse and cat. However, in the cat the number of immunoreactive pinealocytes was very limited. In the pineal organs of the rat and guinea pig immunoreaction was very weak and diffuse. No immunoreaction was observed when the antibody was preabsorbed with purified bovine (rhod)opsin. These findings are in accord with the results of previous studies indicating molecular similarities between retinal photoreceptors and pinealocytes in mammals.

Animals↗
PubMedDate not supplied

Photopigments and circadian systems of vertebrates.

In the retinal degeneration (rd) mouse the absence of rod cells and the progressive loss of cones does not result in a decrease in circadian phase shifting responses to light. By contrast, rd/rd mice are unable to perform simple visual tasks. In addition, rodless transgenic mice, and mice homozygous for the retinal degeneration slow (rds) mutation, show unattenuated circadian responses to light. Collectively these data suggest that cone cells lacking outer segments are sufficient to maintain normal circadian responses to light, or some unidentified photoreceptor within the retina. An action spectrum for circadian responses to light in rd/rd mice, and molecular analysis of retinally degenerate mice and blind mole rat eyes, suggests the involvement of a mid-to-long wavelength sensitive cone opsin in photoentrainment. Extraocular photoreceptors of non-mammalian vertebrates are currently being analyzed in order to identify functional and evolutionary similarities between visual and non-visual photoreceptor systems.

Amino Acid Sequence↗
PubMedDate not supplied

Percutaneous retrieval of foreign bodies: experience with the nitinol Goose Neck snare.

PURPOSE: The authors present their experience with the nitinol Goose Neck snare system in the retrieval of retained foreign bodies in 20 patients. PATIENTS AND METHODS: Foreign bodies were located in the vascular system in 13 patients, urinary tract in four, biliary system in one, gastrointestinal tract in one, and the peritoneal space in one. All retrievals were performed with use of standard angiographic/interventional techniques. RESULTS: Success was achieved in all cases without attendant complications. Foreign bodies removed included catheter and guide-wire fragments, an embolization coil, broken or occluded double pigtail catheters, a Wallstent, and a surgical laparotomy sponge. CONCLUSION: All procedures were performed quickly, safely, and without difficulty. Because of its excellent torque control, positive grasping capacity, excellent radiopacity, lack of traumatic effect, and availability in different sizes appropriate for use in a wide variety of difficult anatomic spaces, the authors recommend that this device be considered the first choice for all foreign body retrieval procedures.

Adult↗
PubMedDate not supplied

Rod photopigment deficits in albinos are specific to mammals and arise during retinal development.

Adult albino mammals have specific retinal defects, including reduced numbers of rod photoreceptors. To examine when this rod deficit arises and whether it exists in nonmammalian albinos, we have used absorbance spectrophotometry to measure photopigment levels in dark-adapted eyes taken from three groups of pigmented and albino animals: adult rodents (rats and mice), developing rats, and mature Xenopus frogs. Rhodopsin concentrations were consistently and significantly reduced in mammalian albinos compared to their wild-type counterparts from before the time of eye opening, but photopigment levels were similar in frogs of both pigmentation phenotypes. The results strongly suggest that deficits in the rod cell population arise early in development of the mammalian albino retina, but do not generalize to nonmammalian mutants lacking retinal melanin.

Albinism, Ocular↗
PubMedDate not supplied

Rhodopsin-like sensitivity of extra-retinal photoreceptors mediating the photoperiodic response in quail.

It has been known for some 50 years that birds use photoreceptors in or near the hypothalamus to mediate the photoperiodic responses that control seasonal breeding. So far, however, attempts to identify the photopigment by determining an action spectrum have failed. The problems stem from the selective filtering of light by the tissues surrounding the photoreceptors and the need to deliver defined amounts of light over the days or weeks required to induce a quantitative measure of photostimulation. Here we have developed a technique which produces a quantitative action spectrum for the photoperiodic response in the Japanese quail; the results indicate the presence of a rhodopsin photopigment with a peak sensitivity of approximately 492 nm. The photoreceptors exhibit a level of sensitivity comparable with that of vertebrate visual pigments. We conclude that the brain photoreceptors of birds are based on a rhodopsin/rhodopsin-like photopigment.

Animals↗