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      DNA Repair in the Lens

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      Ophthalmic Research

      S. Karger AG

      Lens, Hydroxyurea, UV-DNA repair

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          Abstract

          During early embryonic life the lens becomes an autonomous organ system containing the proliferating cells which are the sole contributors to its growth; the lens becomes topographically divided into proliferative (epithelium) and nonproliferative (fiber) compartments (see, for review Cleaver [1]). In nondividing lens fibers, cell nuclei progressively lose DNA, degenerate and disappear [9]. Modak [8] and Modak and Unger-Ullman [10] that terminally differentiating and aging postmitotic cells accumulate lesions in their DNA due to defective DNA repair enzyme machinery. We have shown earlier [2] that as lens fiber cells differentiate there occurs a decrease in the rejoining capacity for single strand breaks in DNA. A precise analysis of DNA repair capacity in the entire lens, or in the epithelium, is hampered by the fact that during two-thirds of the developmental period the cell population increases rapidly [11]. Thus, to demonstrate DNA repair activity, it is necessary to suppress the normal cell division. To this end, we undertook the analysis of thymidine incorporation in the presence of hydroxyurea, a drug known [1] to inhibit scheduled DNA synthesis but not repair synthesis. Our data show that the drug does suppress the incorporation of <sup>3</sup>H-thymidine initially, it also causes stimulation of incorporation during the later phase. Similar to the rabbit lens epithelium [4], the central epithelium from adult bovine lenses has a very low mitotic index [ Tréton et al., unpubl.] indicative of a near total lack of cell proliferative activity. In these, we observe ultraviolet-induced <sup>3</sup>H-thymidine incorporation without the use of hydroxyurea. We also find that protofibers carry out unscheduled DNA synthesis similar to those in rat lens [6].

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          Author and article information

          Journal
          ORE
          Ophthalmic Res
          10.1159/issn.0030-3747
          Ophthalmic Research
          S. Karger AG
          978-3-8055-0862-9
          978-3-318-02127-1
          0030-3747
          1423-0259
          1979
          1979
          03 December 2009
          : 11
          : 5-6
          : 335-340
          Affiliations
          Unité de recherches gérontologiques, U-118, Inserm, Paris and Unite de biologie du Développement, Institut de pharmacologie, CHUV, Lausanne
          Article
          265030 Ophthalmic Res 1979;11:335–340
          10.1159/000265030
          © 1979 S. Karger AG, Basel

          Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher. Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug. Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.

          Page count
          Pages: 6
          Categories
          Growth Control, Differentiation, and Ageing of the Eye Lens

          Vision sciences, Ophthalmology & Optometry, Pathology

          Hydroxyurea, UV-DNA repair, Lens

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