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Biomedical subjects

F J Holly

Publications and source records attributed to F J Holly.

At least 37 records · Page 2Linked to original sources
PubMed1982

Investigation of the accuracy of tear lysozyme determination by the Quantiplate method.

The accuracy of lysozyme concentration determination by the method of measuring lysis diameter in agarose gel slabs containing Micrococcus lysodeikticus bacteria uniformly suspended throughout the gel was determined for various methods of tear sample collection. The effects of storage of lysozyme solution samples at subzero temperatures for several days was also examined. It was found that a power rather than the suggested exponential dependence between the lysozyme concentration and lysis diameter provides the most accurate fit and thus should be used for interpolation. Storing samples frozen in glass capillaries lowered the lysozyme concentration in a predictable manner. When Weck-Cel sponges were used to collect the samples the lysozyme concentration was greatly diminished in a nonlinear manner because of internal adsorption. The relative loss (cause by adsorption) depended on the actual lysozyme concentration as well as on the sample volume/sponge weight ratio. Storing samples absorbed by such sponges in a frozen state further altered the results in an unpredictable way. The observation that smaller tear samples for a given sponge size yielded lower apparent values for lysozyme concentration casts doubt on findings that have reported lower lysozyme concentration in the tears of keratoconjunctivitis sicca patients, where either cellulose sponges or filter paper discs were used for tear collection.

Freezing↗
PubMed1981

Tear film physiology and contact lens wear. II. Contact lens-tear film interaction.

The successful fitting of contact lenses requires the practitioner to take into account many properties of the specific lens type used but the practitioner must also understand patient factors including tear properties, use of appropriate solutions, procedures for lens cleaning, and efficiency of blinking. Selection of appropriate patients, selection of lens type, proper fitting, good maintenance, and training and monitoring of patients increase the probability of achieving success.

Conjunctivitis↗
PubMed1981

Protease activities in human tears.

Several protease activities were measured in human tears by six specific substrates. The specific activity of cathepsin B-like enzyme was 7-fold higher in Orientals than in Caucasians. The trypsin-like and cathepsin C-like enzyme activities also showed 3 to 4-fold higher in Orientals than in Caucasians. However, the deviation in the activities of these two enzymes was high in both Orientals and Caucasians. Similar results were obtained when comparing the protease activities of tear collected by glass capillary and a filter-paper strip method. Since a surface-active small molecular weight fraction can be produced by incubation of freshly collected tears for 4 hours at 37 degrees C, the low molecular weight surfactant may be a proteolytic product.

Asian People↗
PubMed1981

Effect of nonisotonic solutions on tear film osmolality.

We found that the original osmolality of the tear film is regained rapidly subsequent to the installation of hypotonic artificial tears or other nonisotonic solutions. The minor irritation due to nonisotonicity and the increased tear volume both contribute to the increased turnover rate which in turn results in the short half-life (measured in seconds) of these solutions in the eye. Despite the expected fluctuation in tear volume and probably in tear secretion rate during the experiment, the osmolality of the tears followed an exponential decay with relatively good correlation.

Adult↗
PubMed1980

Tear film physiology.

Current understanding of tear film physiology is based on the anatomy of each of the three layers, as well as on the changes that occur with blinking and on the physicochemical properties of the tear fluid. Abnormalities in tear film may be due to deficiency of aqueous tears or mucin, changes in the lipid layer, inadequate blinking, or epithelial pathology. Patients who have marginal deficiencies tend to be symptom-free but will develop symptoms promptly if contact lenses are fitted.

Contact Lenses↗
PubMed1978

Biophysical aspects of epithelial adhesion to stroma.

The affinity of various corneal boundary surfaces, such as mucus-coated epithelium, demucinized epithelium, denuded basement membrane, and keratectomized cornea, to water and hydrophobic liquids was determined by contact angle goniometry on enucleated rabbit eyes. The mucus-coated surface and the bare stromal surface without the basement membrane were found to be more hydrophilic than the surfaces of the epithelium and the basement membrane. If at least one of the surfaces forming a joint boundary is hydrophilic, then conditions become favorable for the accumulation of water at the interface, forming a weak boundary layer that is detrimental to adhesion, due to its low shear resistance. Thus, even in a normal eye, mucus does not adhere strongly to the epithelium; when the basement membrane is damaged or absent, the epithelium does not adhere well to the stroma. External dehydrating factors such as hyperosmotic conditions favor adhesion, whereas edematic conditions have an adhesive (adhesion-decreasing) effect. Experimental ophthalmic solutions containing macromolecules at hyperosmotic concentrations may demonstrate a therapeutic effect when applied to eyes with recurrent epithelial erosion or other epithelial trauma.

Adhesiveness↗
PubMed1977

A tentative mechanism for inferior punctate keratopathy.

We analyzed the blinking motions of ten patients with inferior punctate keratopathy and ten normal subjects by means of time-lapse motion pictures. We also determined the frequency of blinking during one-minute intervals for each individual. Four types of blinking were distinguished: complete, incomplete, twitch, and forced blink. The average blinking frequency was about the same for both groups: 16 to 17 blinks per minute. The relative proportion of complete blinks, however, was much lower in patients with inferior punctate keratopathy than in normal subjects. The impaired blinking motion may be responsible for the punctate staining of the inferior corneal epithelium by producing exposure and inadequacies in the tear film. For this reason, these patients may benefit from blink training, application of tear substitutes, or soft contact lenses more than from the customary prescription of topical cortisone eyedrops.

Blepharitis↗
PubMed1975

Wettability of hydrogels. I. Poly (2-hydroxyethyl methacrylate).

The wettability characteristics of the contact lens material, PHEMA, with respect to water have been determined by using the sessile drop, and the captive air bubble techniques of contact angle goniometry. It is concluded that on PHEMA gels water does not spread spontaneously. Large hysteresis has been observed in the advancing and receding contact angles. This suggests that this hydrogel surface is capable of changing its free energy through reorientation of the polymer side chains and chain segments depending on the nature of the adjacent phase. The water content of the gels does not appear to have an effect on water wettability in the hydration range investigated. The minor wettability differences among the various gels studied were most likely due to differences in surface structure and segmental mobility due to inherent variations in the method of preparation. Small but consistent differences were found between the contact angles measured by the captive bubble method and those obtained by the sessile drop method, the former values being higher. These differences may not be method-related artifacts and cannot be explained at the present time.

Acrylates↗