Biomedical subjects

A Pocobelli

Publications and source records attributed to A Pocobelli.

9 recordsLinked to original sources

PubMed1995

Effect of antidenaturant drugs on lysozyme deposit formation on soft contact lenses by liquid chromatography--electrochemical detection.

The effect of some antidenaturant drugs on the formation of lysozyme deposits on soft contact lenses was investigated by in vitro experiments. Results were obtained which encourage the use of this strategy to reduce lens spoilage. At the same time emphasis is given to the possibility that some functionalities (i.e. lysine groups) present in drug molecules could promote protein adsorption. In order to evaluate at a quantitative level the effectiveness of the drugs used to minimize the formation of deposits on soft contact lenses, a selective method for the determination of adsorbed lysozyme was developed. It is based on the hydrolysis of the 'lens/adsorbed lysozyme' system, followed by high performance liquid chromatography coupled to electrochemical detection of the released tryptophan residues. The lysozyme calibration curve was linear up to 5 mg ml-1 and the detection limit was 5 ng injected.

Adsorption↗

PubMed1992

Two methods of examining protein deposits on hydrophilic contact lenses.

Our aim in these studies has been to develop spectroscopic techniques for quantitative analysis of the early phases of protein deposition on soft contact lenses. We produced protein deposition in vitro by soaking lenses in a 0.025% chloral hydrate lysozyme solution at 37 degrees C. Two groups of lenses were so treated: one for 15 days and the other for 6 months. The study of in vivo deposits was carried out on lenses used by healthy wearers. From the same six patients we obtained two consecutive groups of 12 lenses: one group worn for 8 hours and the other group worn for 7 days. We tested the lenses by an indirect (destructive) method (based on a colorimetric assay of amino acid complexes obtained by basic hydrolysis) and by a direct (non-destructive) method consisting of spectrophotometry performed on intact lenses. Using the indirect method we found that the lenses absorbed in vitro for 6 months had lysozyme deposits of 5 +/- 1 micrograms; while the lenses adsorbed for 15 days supplied an average of 0.8 +/- 0.3 micrograms of lysozyme. Lenses worn by healthy volunteers show protein deposition equivalent to a lysozyme quantity ranging from 0.8 to 1.6 micrograms. We found a lower limit of detection with the direct method of approximately 5 micrograms, limiting its applicability.

Adsorption↗

PubMed1991

Use of bendazac lysine to limit protein deposition on soft contact lenses in vitro.

We used the heat denaturation of lysozyme to induce the in vitro formation of protein deposits on 60 poly-HEMA contact lenses (38.6% water). Each lens was individually placed in 20 mL of a 0.04% lysozyme solution. The lenses were divided into two equal groups. In the first group (30 lenses), bendazac lysine (100 mg) was added to the lysozyme solution. The second group of lenses was used as control. Quantitative analysis of protein deposits on the lenses of both groups was carried out by a colorimetric test. In the lenses where deposit formation occurred in the presence of bendazac lysine, a mean protein level of 7.17 +/- 3.42 micrograms per lens was found; in the control group the mean value was 30.6 +/- 8.22 micrograms per lens. Student's t-test showed this difference to be significant (P less than 0.001).

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed1988

[Does a iatrogenic damage caused by dacryography exist?].

This study was aimed at investigating the changes in corneal epithelium caused by dacryocystography. Such changes can be either chemical--from iodate contrast media (iodized oil and water-soluble non-ionic cm)--or physical--from needle or catheter. Twenty-five patients (50 eyes) were studied using BUT, Schirmer tests, biomicroscopy, and pachymetry. Follow-ups immediately after dacryocystography demonstrated superficial keratitis, which was less severe with water-soluble non-ionic cm. Such lesions were hardly ever observed in patients who had been treated with dacriosol ointment on the cornea just before the X-ray exam. Follow-ups at 24 hours showed the superficial keratitis to have disappeared in all patients, independent of the kind of cm employed and of the ophthalmic ointment applied to the cornea.

Adult↗

PubMed1966