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The effect of enzymatic contact lens cleaning on adherence of Pseudomonas aeruginosa to soft contact lenses.

Previous studies have demonstrated that Pseudomonas aeruginosa adheres more readily to soft contact lenses with a mucin coating than to unworn contact lenses. The mucin coatings that develop on soft contact lenses may, therefore, play a significant role in the pathogenesis of contact lens-associated Pseudomonas corneal ulceration. We tested the ability of a variety of enzymatic contact lens cleaners and other enzyme solutions to decrease the adherence of Pseudomonas to mucin-coated soft contact lenses. Of the commercially available solutions that were tested, cleaning with Optizyme and Extenzyme significantly reduced the adherence of Pseudomonas to the lenses, whereas cleaning with the Softmate Weekly Cleaning System had no effect. Optizyme and Extenzyme were as effective as a 10% solution of acetylcysteine and more effective than a 0.25% trypsin solution. Neuraminidase at pH 5 was the most effective solution at reducing the adherence of Pseudomonas to the lenses, supporting the finding that sialic acid is a specific receptor for Pseudomonas aeruginosa. Soft contact lenses should be cleaned frequently with an effective enzymatic cleaner to reduce the likelihood of Pseudomonas adhering to the lens and thereby reduce the incidence of Pseudomonas corneal ulceration in soft contact lens wearers.

Acetylcysteine↗

[Isotopic effect in enzymatic oxidation of methane].

The isotopic effect during oxidation of methane and deuteromethane by a suspension of Methylomonas rubrum cells, for which methane is the only source of carbon, was observed. The rate of CH4 oxidation is 12.5 times higher than that of CH4 oxidation. It is demonstrated that CD4 is a competitive inhibitor of CH4 oxidation. The results obtained suggest that the disruption of the C-H bond is the limiting step of enzymatic oxidation of methane.

Deuterium↗

The effect of enzymatic removal of sialic acids on the functional properties of protein C.

The effect of enzymatic removal of sialic acid residues on the functional properties of human protein C was examined. The rates of activation of native and asialo protein C were identical using either the thrombin thrombomodulin complex or the snake venom activator, protac. Desiaylated activated protein C (APC) was, two-three-fold more active than native protein C, both as an anticoagulant and in its ability to hydrolyze chromogenic substrates. The potentiating effect of the desialylation was confirmed by initially fully activating protein C followed by the desialylation process. In these studies, a two-three-fold enhancement in the activity of the protein was observed which paralleled the extent of the desialylation. The activity of asialo-protein C was completely abolished by monoclonal and polyclonal antiprotein C antibodies, confirming that the effect was mediated by APC. Our studies suggest that the sialic acid component of protein C is not essential for the expression of APC activity but may act to modulate the function of the protein.

Humans↗

Effect of enzymatic induction and inhibition on cyclophosphamide-induced sister chromatid exchange in vivo.

The influence of the enzymatic inducer beta-naphthoflavone (BNF) and of the inhibitors alpha-naphthoflavone (ANF) and 2-diethylaminoethyl-2,2-diphenylvalerate HCl (SKF 525-A) on the frequency of sister chromatid exchanges (SCE) induced by cyclophosphamide (CPA) was studied in vivo in C57BL/6J male mice. Neither inducer nor inhibitors substantially modified the SCE level induced by 5 or 10 mg/kg CPA. The enzymatic induction by BNF was effective as treated animals showed a reduced paralysis time by zoxazolamine whereas ANF appeared to be ineffective. The enzymatic inhibition by SKF 525-A was confirmed by a longer sleeping time in pentobarbital-treated mice and also by a longer paralysis in zoxazolamine-treated mice. The lower susceptibility to CPA-induced SCEs of C57BL/6J mice relative to DBA/2 strain observed in a previous work seems not to be simply related to Ah locus mediated metabolism.

Animals↗