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Biomedical subjects

R A Weale

Publications and source records attributed to R A Weale.

At least 127 records · Page 7Linked to original sources
PubMed1969

Flash bleaching of rhodopsin in the human retina.

1. Measurements were made of the photo-sensitivity of rhodopsin in the living human retina following bleaching with (a) a flash less than 1 msec in duration, (b) a continuous exposure lasting 30 sec.2. The apparatus consisted of a fundus reflectometer coupled to a computer for on-line processing. Three subjects were studied.3. The relations between the quantity of pigment bleached and the incident energy are so similar for the flash and continuous exposure tests that the occurrence of photo-reversal (such as has been reported in similar circumstances for visual pigment in solution) seems to be ruled out.4. Nonetheless, the two experimental conditions lead qualitatively to two different photo-chemical states in as much as the density difference spectrum for the flash exposure is displaced toward longer wave-lengths in comparison with the data obtained with the continuous exposure.5. The results are discussed with reference to the sequence of events following the bleaching of visual pigments solutions as reported by other workers.

Fundus Oculi↗
PubMed1969

The optical activity of bleached retinal receptors.

1. A study was made of the birefringence of retinal receptors obtained from the retinae of frogs, cats, rabbits and goldfish.2. Normal rods and cones show similar optical activity.3. The effects of fixatives, lipid solvents, de- and rehydration, and temperature were examined.4. Rods fixed with formaldehyde preserve normal optical activity for a long time while glutaraldehyde changes it swiftly in a manner similar to that resulting from the application of heat.5. Alcohol acts like a denaturing agent rather than as a solvent for rod lipids.6. The action of glutaraldehyde on goldfish rods is instantaneous but cones preserve their normal activity for up to 1 hr.7. A number of striking parallels between the presence of the R2 component of the early receptor potential (as reported in the literature) and optical activity are listed; it is suggested that normal optical activity is a prerequisite for the recording, if not the elicitation, of R2.

Animals↗
PubMed1969

Color vision.

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Animals↗
PubMed1966

Polarized light and the human fundus oculi.

1. Measurements were made of the relative fractions of diffuse and specular reflexions in the fovea and periphery of the human fundus oculi.2. All the light emerging from the eye is scattered or reflected behind the receptors as bleaching the retina affects both fractions equally.3. Bruch's membrane is the most likely surface at which specular reflexion occurs whereas the choroid and sclera are probably involved in scattering.4. Both diffuse and specular components show marked directional effects that vary with wave-length.

Adult↗