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Biomedical subjects

W H Coles

Publications and source records attributed to W H Coles.

17 recordsLinked to original sources
PubMed1991

Antioxidant enzymes in human tears.

Minimally stimulated tear samples collected from human subjects were assayed for the major antioxidant enzymes: superoxide dismutase, catalase and glutathione peroxidase. No catalase or glutathione peroxidase activity was detected. However, human tear film does contain the CuZn superoxide dismutase (103 +/- 32 ng/mg soluble protein), which is inactivated by hydrogen peroxide (0.2 mM). These data indicate that the tear film has the enzyme generally required for control of inflammatory conditions but is lacking the usual physiological defense systems against the toxicity of hydrogen peroxide. Concern has been raised as to the safety of contact lens disinfectant solutions containing hydrogen peroxide. These results indicate that the tear film is lacking the enzyme systems to provide significant protection to the cornea, to the tear film itself, or to the SOD of the tear film from the oxidant action of hydrogen peroxide.

Adult↗
PubMed1989

Teaching the informed consent process to residents.

We believe the focus and emphasis of this committee on informed consent is unique, and that the development of an informed consent teaching process for residents will focus on the moral and ethical issues regarding informed consent. Even more important, we believe we will emphasize the patient care aspects of informed consent and also teach residents their responsibilities for long-term patient care with regard to patients' satisfaction and understanding of their disease process.

Informed Consent↗
PubMed1989

Kinetics of corneal epithelial maintenance and graft loss. A population balance model.

We use a population balance model to study the mechanism and the rate of centripetal migration of epithelial cells, renewal of the corneal epithelial population by the cell derived from (progeny of) the limbal stem cells and the kinetics of the replacement of the donor corneal epithelium. The epithelial mass is constant under the normal circumstances and therefore the rate of cellular entry due to centripetal motion and mitosis into any epithelial volume must equal the cell loss from the same volume. The magnitude of the centripetal velocity and the rate of replacement of the donor tissue following keratoplasty are shown to depend only on the following directly quantifiable factors--the difference in the mitotic rates of the corneal and limbal epithelia and the radii of these two epithelia. The a priori model predictions are found to be in very good agreement with the observed centripetal velocities and the rate of corneal graft replacement. The model provides an independent support for the hypothesis that the stem cells for the corneal epithelium are located in the limbus and are responsible for a slow replenishment of the corneal epithelial cell. The model suggests some factors that diminish the centripetal supply of cells and thus provides insights into the pathogenesis of persistent corneal defects and delayed reepithelialization of defects and grafts. The model is suitable for interpreting and quantitatively correlating the influence of some epithelial alterations and drugs on the centripetal supply of epithelial cells.

Animals↗
PubMed1979

Corneal endothelium: a modified method for cultivation.

A modified method for establishing cultures of rabbit corneal cells is described. The new technique utilized a Lucite disc in combination with a Tygon ring for growth of pure cell cultures and was compared with an explant method for growing cells. Each method provided adequate cell cultures for biochemical or ultrastructure studies of rabbit corneal cells, but the ring and disc method described here allowed the isolation of specific cell types without the interference of stromal cell contamination.

Animals↗
PubMed1977

Signs of essential blepharospasm: a motion-picture analysis.

Motion pictures of 15 patients with essential blepharospasm were studied. Previously unrecognized signs indicated multiple cranial nerve involvement. These signs include impersistence of gaze, lid retraction, tongue thrust, head tilts, head jerks, vertical gaze spasms, and asymmetry. The sugns were also observed in a patient with bilateral blepharospasm who had a history of Bell's palsy suggesting facial nerve injury as a possible factor in blepharospasm. The presence of these signs can be explained by known neural pathways, but the site, or sites, of the lesion remains obscure. These signs may be important in assessing severity and in treatment evaluation.

Adult↗
PubMed1975

Pilocarpine toxicity. Effects on the rabbit corneal endothelium.

The effects of pilocarpine on the healthy rabbit corneal endothelium were studied by in vitro perfusion, photography, and electron microscopy. The toxicity of endothelial cells to pilocarpine was doserelated. Photography showed shrinkage of cells exposed to pilocarpine. The most striking ultrastructure changes were margination of nuclear heterochromatin and cytoplasmic vacuolation.

Animals↗
PubMed1975

Effects of antibiotics on the in vitro rabbit corneal endothelium.

The effects of ten antibiotics and two preservatives on the rabbit corneal endothelium were studied by in vitro perfusion. Dose-related effects on corneal thickness were seen with certain antibiotics. No correlation was found between structure, origin, or bacterial sensitivity of the antibiotics and their effect on corneal transplants. Five distinct morphological changes were observed: two were transient and only one was specific. Although clinical dose correlation was not intended, further investigation is needed on erythromycin, bacitracin, chloramphenicol, penicillin, oxacillin, and cephalothin.

Alcohols↗
PubMed1973

Vitrectomy.

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Adolescent↗