Intraocular lens opacification after corneal endothelial keratoplasty: electron microscopy and x-ray element spectroscopy analysis.

PURPOSE: To assess a newly recognized long-term complication of Descemet-stripping automated endothelial keratoplasty (DSAEK). SETTING: Plymouth Royal Eye Infirmary and Plymouth Electron Microscope Centre, Plymouth, United Kingdom. DESIGN: Retrospective case series. METHODS: This study evaluated cases of intraocular lens (IOL) opacification that developed after uneventful DSAEK. None of the IOLs was previously known to opacify. In 1 case, the opacified IOL was explanted and analyzed using detailed light microscopy, scanning electron microscopic (SEM) analysis, and element x-ray spectroscopy. RESULTS: In all 5 cases, the IOL was hydrophilic acrylic and the eye developed IOL anterior surface opacification 4 to 12 months after DSAEK. In 1 eye, the opacification was symptomatic; thus, an IOL exchange was performed. Light microscopy and SEM analysis of the explanted IOL confirmed opacification on the anterior surface and subsurface areas. X-ray element spectroscopy showed the granules were composed of calcium and phosphorous. CONCLUSIONS: These cases indicate that IOL opacification after DSAEK is a late, although newly recognized, complication of endothelial keratoplasty. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.

Effects of hyperoxia on the permeability of 16HBE14o- cell monolayers--the protective role of antioxidant vitamins E and C.

The use of hyperoxia for critically ill patients is associated with adverse impacts resulting in lung injury accompanied by inflammation. The aim of this study was to evaluate aspects of mechanisms that contribute to hyperoxia-induced disruption of the epithelial permeability barrier, and also the protective effects of the antioxidants α-tocopherol and ascorbate. 16HBE14o- cells were cultured as monolayers at an air-liquid interface for 6 days, after which transepithelial electrical resistance reached 251.2 ± 4.1 Ω.cm(2) (mean ± standard error of the mean). They were then exposed for 24 h to normoxia (21% O2, 5% CO2), hyperoxia (95% O2, 5% CO2), hyperoxia with 10(-7) M α-tocopherol, hyperoxia with 10(-7) M ascorbate, hyperoxia with 10(-6) M ascorbate, and hyperoxia with a combination of α-tocopherol and ascorbate (10(-7) M and 10(-6) M, respectively). Significant reductions (P < 0.05) in transepithelial electrical resistance seen after hyperoxia (with or without antioxidants) were associated with reductions in the levels of zona occludens-1 (ZO-1) observed by immunohistochemistry, and downregulation of ZO-1 expression (P < 0.01) as compared with normoxia. In contrast, the expression levels of interleukin (IL)-8, IL-6 and tumour necrosis factor-α (TNF-α) were increased after hyperoxia (P < 0.01), and marked increases in the levels of these cytokines (ELISA) were seen in the medium (P < 0.001) as compared with normoxia. The antioxidant vitamins E and C had a partial protective effect against the hyperoxia-induced reduction in ZO-1 levels and the increase in levels of the proinflammatory cytokines IL-8, IL-6, and TNF-α. In conclusion, hyperoxia-induced epithelial disruption is associated with tight junction weakening, and induction of a proinflammatory environment.

Regulation of Schwann cell differentiation and proliferation by the Pax-3 transcription factor.

Pax-3 is a paired domain transcription factor that plays many roles during vertebrate development. In the Schwann cell lineage, Pax-3 is expressed at an early stage in Schwann cells precursors of the embryonic nerve, is maintained in the nonmyelinating cells of the adult nerve, and is upregulated in Schwann cells after peripheral nerve injury. Consistent with this expression pattern, Pax-3 has previously been shown to play a role in repressing the expression of the myelin basic protein gene in Schwann cells. We have studied the role of Pax-3 in Schwann cells and have found that it controls not only the regulation of cell differentiation but also the survival and proliferation of Schwann cells. Pax-3 expression blocks both the induction of Oct-6 and Krox-20 (K20) by cyclic AMP and completely inhibits the ability of K20, the physiological regulator of myelination in the peripheral nervous system, to induce myelin gene expression in Schwann cells. In contrast to other inhibitors of myelination, we find that Pax-3 represses myelin gene expression in a c-Jun-independent manner. In addition to this, we find that Pax-3 expression alone is sufficient to inhibit the induction of apoptosis by TGFß1 in Schwann cells. Expression of Pax-3 is also sufficient to induce the proliferation of Schwann cells in the absence of added growth factors and to reverse K20-induced exit from the cell cycle. These findings indicate new roles for the Pax-3 transcription factor in controlling the differentiation and proliferation of Schwann cells during development and after peripheral nerve injury.

Elevated oxygen fraction reduces cilial abundance in explanted human bronchial tissue.

The effect of hyperoxia on ciliary abundance in cultured explants of adult human bronchus was investigated. Bronchus samples were removed during surgery from patients receiving pneumonectomy or lobectomy for malignancy. Part or all of each of these samples was used for measurement of cilial abundance by scanning electron microscopy (SEM); in many cases the remainder was subdivided and cultured at 37 degrees C in DMEM medium, maintaining an air interface at the ciliated surface of each segment. Cultured segments were exposed to normoxia or hyperoxia (95% O(2)), and a segment was removed every other day for quantification of cilial abundance by SEM. There was a significant inverse relationship between smoking history and abundance (p = .017; ANOVA); mean values for nonsmokers, ex-smokers, and smokers were 98.2% (n = 6), 97.0% (n = 17), and 84.02% (n = 9), respectively. There was some loss of cilia on explant segments cultured under normoxia, but the rate of loss from segments cultured under hyperoxia was significantly greater (W test, p = .00011); rate constants (means +/- SE) for cilial loss of 0.0208 +/- 0.0044 day(-1) and 0.0880 +/- 0.0179 day(-1) were found for explant segments exposed to 21 and 95% O2, respectively (n = 20).