Biomedical subjects

C Keeler

Publications and source records attributed to C Keeler.

At least 19 recordsLinked to original sources

PubMed1999

NMR of samples containing metal foils.

By using spool configurations of a sample containing aluminum foil, in which the axis of the spool is collinear with the RF coil axis, one can obtain high-quality 13C NMR spectra of static samples of organic material attached to the aluminum foil. By combining such a spool configuration (or, alternatively, analogous samples containing equivalent amounts of fine aluminum powder) with the magic-angle hopping (MAH) technique, one can achieve a high degree of isotropic averaging of the 13C spectrum. This opens to NMR techniques the study of a variety of samples containing macroscopic pieces of metal foils, e.g., thin films deposited on metal foils and electrochemical systems with species adsorbed on metal-foil electrodes.

Aluminum↗

PubMed1994

Functional morphology of the nictitating membrane in the domestic cat.

Morphological differences between the corneal and palpebral surfaces of the nictitating membrane of the domestic cat were examined using histology, histochemistry and the scanning electron microscope. Both surfaces are covered by one or two layers of epithelial cells. The epithelium contains numerous goblet cells, particularly on the palpebral side. These cells revealed binding sites for six lectins as well as positive PAS reactivity, and alcianophilia at both pH 2.5 and pH 3.5. Numerous lymph follicles located on the corneal side make the epithelium look like lymphoepithelial tissue. Accumulations of lymphatic tissue may also be found on the palpebral side. Scanning electron micrographs showed microvilli on the epithelial surfaces. The function of the cat nictitating membrane is discussed on the basis of our findings and those of other authors. Movements of the nictitating membrane alternate between active and passive phases of gliding. The membrane as a whole effectively protects the nasal portion of the bulb from dust, dehydration and pathogens.

Animals↗

PubMed1994

Ultrastructure and regression of the tunica vasculosa lentis in newborn Wistar rats.

In this study, regression of the hyaloid vessels has been followed in the tunica vasculosa lentis (TVL) of the Wistar rat using light, transmission and scanning electron microscopy. The investigation extended from the 1st to the 32nd postnatal day. On day one, the posterior tunica vasculosa lentis is made up of radiating capillaries connected by side-arm branches, the vascular walls of which possess a continuous endothelium, a basement membrane and an incomplete pericyte covering. Endothelial cell specialization is apparent in the form of extreme thinning and fenestration in capillary regions lying opposite the lenticular capsule. The earliest detectable regressive changes become apparent on approximately day 3 and initially involve the short connecting capillaries surrounding the posterior pole of the lens and proceed from there. Regression takes place in the presence of rarefaction of vessel wall cells and the accumulation of endothelial cells in the adjacent capillaries. This leads to the formation of acellular channels which are made up of only basement membrane tubes. After the complete disappearance of these transitional acellular channels, the capillary meshwork coarsens. Remnants of these capillaries are detectable until the 30th postnatal day.

Aging↗

PubMed1987