Biomedical subjects

J L Sokol

Publications and source records attributed to J L Sokol.

4 recordsLinked to original sources

PubMed1990

Layer-by-layer desquamation of corneal epithelium and maturation of tear-facing membranes.

A method to devitalize single layers of apically exposed rabbit corneal epithelial cells through the use of digitonin is described. Devitalized cells exfoliate spontaneously as loosely cohesive, trypan-blue-stained layers, exposing underlying viable cells. Repeated application of this devitalization-exfoliation methodology results in the gradual elimination of each of the epithelial cells. The generation of corneal surfaces composed of the tear-facing membranes of all intraepithelial cell types--subsurface, wing, and basal--is thus attainable. Exposed surfaces were studied with respect to microanatomy, the binding of lectins, and the adherence of Pseudomonas aeruginosa. Microprojections (microvilli or microplicae) were absent in the basal cells but were present in all suprabasal layers, and increased gradually in density as cells approached the surface position. Wheat germ agglutinin and concanavalin A were found to bind to the tear-facing membranes of all suprabasal cell layers. The tear-facing membrane of the basal cells, in contrast, was not labeled. Within each labeled layer, the magnitude of lectin binding differed markedly from cell to cell; lectin binding decreased as the cellular area exposed to the tear surface increased. Pseudomonas were found exclusively at microprojection-free cellular areas, suggesting that inhibition of attachment is linked to the ontogeny of these microprojections.

Animals↗

PubMedDate not supplied

Automated mechanical thermometry probe mapping systems for hyperthermia.

In order to better assess temperature distribution patterns in patients, tissue equivalent phantoms, and experimental animals, mechanical devices and automated control systems for positioning temperature probes in implanted catheters and catheters laid on the skin surface have been developed. They employ stepper motor actuated roller and idler wheel drives to move the probes. Two devices incorporate positive positioners in addition to the drive rollers in order to obtain higher positioning accuracy where significant probe to catheter friction is present. Automated systems have been constructed which can simultaneously position, record and display data from up to 10 temperature sensors in a colour-coded position versus temperature format to produce a real time two-dimensional colour-coded pseudo isotherm display. These thermal mapping devices have been used for characterizing the power deposition patterns of several large area microwave applicators (on the surface and at depth within tissue equivalent phantoms), for intraorgan temperature mapping in experimental animals, and for surface and subcutaneous temperature mapping during clinical treatments.

Animals↗

PubMedDate not supplied

Influence of water bolus temperature on measured skin surface and intradermal temperatures.

Temperature measurements utilizing thermometry probes placed on the skin surface are often used clinically to assess temperatures for the purposes of power control and evaluating treatment efficacy. There is a question, however, as to what extent applicator temperature-controlled liquid coupling boluses can create temperature gradients which can cause significant differences between measurements taken by sensors placed on the skin surface and the actual temperature of the tissue beneath. To address this question, experiments were conducted with human subjects instrumented with surface and shallowly implanted temperature sensors. Microwave applicators with circulating bolus water set at 21 and 41 degrees C were used to induce a temperature gradient in depth in the superficial tissue by thermal conduction. No microwave energy was applied. The average measurement offset at 41 degrees C was 15% of the difference in temperature between the interstitially measured skin temperature and the coupling bolus temperature, towards the temperature of the coupling bolus. The corresponding offset with coupling boluses set near 21 degrees C was 32%. Different water bolus types and volumes were observed to induce different percentage offset errors.

Connective Tissue↗

PubMedDate not supplied

A study of patient compliance in a contact lens-wearing population.

The incidence of corneal infections among the almost 20 million Americans who wear contact lenses, while still small, is rising rapidly. Patient non-compliance with instructions for proper lens care is partly at fault. The general phenomenon of patient non-compliance has been widely studied, most often by using the Health Belief Model (HBM). We report here on 50 consecutive patients fit with contact lenses by one ophthalmologist who were questioned by telephone regarding their lens care practices and beliefs. Forty-four percent of this group wore contact lenses for therapeutic reasons; the remainder wore them for either cosmetic reasons (34%) or convenience (22%). Adherence to published lens care guidelines was used as a basis for segregating patients into a compliant and a non-compliant group. By the criteria selected, 46% of the sample was non-compliant in their lens care. An analysis of responses from each group was structured in terms of HBM dimensions. Our aim was to determine whether there were differences in the beliefs held by compliant vs. non-compliant patients. Age under 30 and obtaining lenses for cosmetic or convenience reasons were the two variables statistically associated with non-compliant behavior. At least one undesirable belief representing each of the four HBM dimensions was found to be positively correlated with non-compliant lens use. The HBM is an effective model with which to investigate the relationship between non-compliant behavior and the rise in contact lens-related complications.

Adolescent↗