Ivan Stefanovic

Glutathione S‐transferase omega‐2 polymorphism Asn142Asp modifies the risk of age‐related cataract in smokers and subjects exposed to ultraviolet irradiation

Glutathione S‐transferase omega‐1 and 2 have a unique range of enzymatic activities, including the regeneration of ascorbate by their dehydroascorbate reductase activities. Because these enzymes could have a protective role from oxidative damage in the lens, the question of whether the two coding glutathione S‐transferase omega polymorphisms confer the risk of age‐related cataract was addressed.

Poly(urethane‐dimethylsiloxane) copolymers displaying a range of soft segment contents, noncytotoxic chemistry, and nonadherent properties toward endothelial cells

Polyurethane copolymers based on α,ω-dihydroxypropyl poly(dimethylsiloxane) (PDMS) with a range of soft segment contents were prepared by two-stage polymerization, and their microstructures, thermal, thermomechanical, and surface properties, as well as in vitro hemo- and cytocompatibility were evaluated. All utilized characterization methods confirmed the existence of moderately microphase separated structures with the appearance of some microphase mixing between segments as the PDMS (i.e., soft segment) content increased. Copolymers showed higher crystallinity, storage moduli, surface roughness, and surface free energy, but less hydrophobicity with decreasing PDMS content. Biocompatibility of copolymers was evaluated using an endothelial EA.hy926 cell line by direct contact, an extraction method and after pretreatment of copolymers with multicomponent protein mixture, as well as by a competitive protein adsorption assay. Copolymers showed no toxic effect to endothelial cells and all copolymers, except that with the lowest PDMS content, exhibited resistance to endothelial cell adhesion, suggesting their unsuitability for long-term biomedical devices which particularly require re-endothelialization. All copolymers exhibited excellent resistance to fibrinogen adsorption and adsorbed more albumin than fibrinogen in the competitive adsorption assay, suggesting their good hemocompatibility. The noncytotoxic chemistry of these synthesized materials, combined with their nonadherent properties which are inhospitable to cell attachment and growth, underlie the need for further investigations to clarify their potential for use in short-term biomedical devices.

MTHFR C677T Homozygous Mutation in a Patient with Pigmentary Glaucoma and Central Retinal Vein Occlusion

Purpose: We present the rare case of a young male patient with asymmetric ocular findings: pigmentary ocular hypertension associated with nonischemic central retinal vein occlusion (CRVO) in the right eye and pigmentary glaucoma (PG) with progressive glaucomatous optic damage in the left eye. Patients and Methods: A 31-year-old man showed nonischemic CRVO in the right eye and the clinical triad of pigment dispersion syndrome in both eyes, however more marked in the left eye. Best-corrected visual acuity was logMAR 0.3 in the right eye and 1.0 in the left eye at presentation. The single risk for developing PG and CRVO was hyperhomocysteinemia. The patient was a carrier of the methylenetetrahydrofolate reductase C677 homozygous mutation. Results: At 18 months of follow-up, visual acuity remained stable, intraocular pressure was in the normal range, but retinal tomography indicated an increase in glaucomatous optic damage to the nerve fiber layer in almost the complete temporal-inferior sector of the left eye, but without visual field defects in the left eye. Retinal tomography and automated perimetry were normal in the right eye. The patient received topical antiglaucomatous therapy. Conclusion: Higher levels of plasma homocysteine, even mildly elevated ones, could be associated with nonischemic CRVO and PG, especially when related to genetic risk factors or C677T mutation.

Achieving Opposites Simultaneously: A Review of Organizational Ambidexterity

The interaction between contemporary organizations and their environment is becoming more sophisticated. Organizations are facing an unpredictable and more complex environment than ever before, which is why they ought to pay attention to a much larger number of variables in the environment and their dynamics than was the case before (Stefanovic et al., 2012). Numerous tendencies within the environment such as technology shifts, the increased influence of information and communication technology on organizational operations, deregulation, the changing face of competition, increased market transparency, more demanding and informed customers, changing economic and political structures, and the transformation of information and knowledge into the key economic resources have had a great impact on the majority of organizations (Stefanovic et al., 2011). Thus, the business environment today may be seen as discontinuous because the mapping from firm actions to performance outcomes changes frequently, profoundly, and in ways that are difficult to predict (cf. Siggelkow and Rivkin, 2005). The environment discontinuity means the existence of any event in the environment that organizations cannot cope with on the basis of their existing capabilities and resources or the existence of events that could not be anticipated by the organization and therefore the organization is not able to adapt accordingly in the short term, even though it had the necessary resources and capabilities (Stefanovic et al., 2012).

Contents Vol. 43, 2010

Anatomy, Pathology and Cell Biology A. Prescott, Dundee Biochemistry, Molecular Biology and Molecular Genetics J. Graw, Neuherberg Clinical and Epidemiological Research M. Kojima, Kahoku Clinical Retina P. Wiedemann, Leipzig Cornea and Ocular Surface C. Marfurt, Gary, Ind. Glaucoma M. Coroneo, Sydney Immunology and Microbiology U. Pleyer, Berlin Lens and Cataract S. Varma, Baltimore, Md. Miscellaneous U. Pleyer, Berlin Neuro-Ophthalmology and Vision Sciences P. Aydin, Ankara Ocular Oncology M. Jager, Leiden Physiology, Pharmacology and Toxicology A. Wegener, Bonn Retina and Retinal Cell Biology M. Boulton, Gainesville, Fla. P. Wiedemann, Leipzig Editorial Board