Dr. Krisztina Valter

Biography

In 1986, I graduated at the Semmelweis Medical University, Budapest, Hungary, as MD cum laude. Following my graduation, I took up a position as an ophthalmic registrar in the Hospital of the Hungarian Railways (MAV). I achieved a magna cum laude grade in my Fellowship exams and was admitted to the Society of Hungarian Ophthalmologists. I emigrated to Australia in 1991 and was awarded an Australian Postgraduate Award (APA) to conduct research for a PhD in medicine in the Dept of Anatomy and Histology at the University of Sydney to carry out studies on environmental controls of death and survival of photoreceptors in mammalian retina. I was awarded my PhD degree in 2000. I moved to the ANU at the beginning of 2003. In 2004-5 I served as the Neuroscience Student Advisor at the ANU and became a member of the Medical Science Board of Studies at the ANU. I am a Chief Investigator in the ARC Centre of Excellence in Vision Science.

Research Interests

My research has been focused on degenerative diseases of the retina, from the molecular and cellular level, to the clinical. My published work has made an impact in two particular areas: (1) The role of oxygen levels in the stability and degeneration of photoreceptors; and (2) the retina's ability to self-protect against stress, using the regulated expression of protective factors. In the former area I was the first to demonstrate the oxygen dependence of several forms of photoreceptor degeneration; in the latter I have shown the sites of trophic factor binding to organelles of the photoreceptor. These lines of research have led to the formulation and testable hypotheses concerning the mechanisms that either damage or protect photoreceptors. Using the light-induced model of retinal degeneration, I was able to test the effects of protective factors and investigate their action mechanism on the stressed retina. To characterise this model further, I started to investigate the role of mitochondrial damage, metabolic changes and oxidative damage in light-induced photoreceptor injury.

In the past 3 years I have been working on cell biology-based, non-invasive therapeutic approaches to manage retinal degenerations. I have been assessing the effects of light management, photobiomodulation (using near-infrared light irradiation) and dietary saffron on the progress of retinal photoreceptor damage or death. I tested these approaches on models of retinal degeneration, with both environmental and genetic background. I was able to demonstrate that light management is a relatively simple and cost-effective way to slow retinal degeneration, at least in some forms of retinal degenerations (in the P23H-3 model). I also showed that photobiomodulation can slow degeneration in the developing P23H-3 retina, as well as protect from light-induced degeneration. Experiments with saffron supplementation also showed that it is potentially a valuable tool in slowing or preventing some forms of degenerations.

Presently, I'm using the light-induced degenerative model to establish the role of inflammation in retinal degeneration.

Recent Publications (since 2003)

Peer-reviewed Articles

• Natoli, RN., Provis, J., Valter,K., Stone, J.: Gene regulation induced in the C57BL/6J mouse retina by hyperoxia: a temporal microarray study Molecular Vision, 2008 July 17 accepted for publication
• Natoli, RN., Provis, J., Valter,K., Stone, J.: Expression and role of the early response gene Oxr1 in the hyperoxia-challenged mouse retina. Epublish 2008, June 6 as Manuscript iovs.08-1722 (JIF:3.776)
• Stone, J., van Driel, D., Valter, K., Rees, S., Provis, J.: The locations of mitochondria in mammalian photoreceptors: relation to retinal vasculature. Brain Res 2008;1189:58-69, Epub 2007 Nov 7 doi.10.1016/j.brainres.2007.10.083 (JIF:2.687)
• Chrysostomou, V., Stone, J., Stowe, S., Barnett, N., Valter, K.: The status of cones in the rhodopsin mutant P23H-3 retina:light-regulated damage and repair in parallel with rods. Invest Ophthalmol Vis Sci 2008;49(3):1116-25, DOI:10.1167/iovs.07-1158 (JIF:3.776)
• Bravo-Nuevo, A., Williams, NK., Valter, K., Stone, J.: Relationship between mitochondrial DNA damage and photoreceptor death in developing and adult retina, assessed in normal and degenerative rat strains. Mitochondrion 2007; 7(5):340-346
• Jozwick C, Valter K, Stone J. : Reversal of functional loss in the P23H-3 rat retina by management of ambient light. Exp Eye Res. 2006 ; 83(5):1074-80
• Wellard, J., Lee, D., Valter, K., Stone, J.: Photoreceptors in the rat retina are specifically vulnerable to both hypoxia and hyperoxia. Vis. Neurosci, 2005; 22(4):501-7
• Valter, K., Bisti, S., Gargini, C., Di Loreto S., Maccarone, R., Cervetto, L., Stone, J : Timecourse of neurotrophic factor upregulation following unilateral optic nerve section. Invest Ophthalmol Vis Sci 2005; 46(5):1748-54
• Gargini, C., Bisti, S., Demontis, G., Valter, K., Stone, J., Cervetto, L.: ERG changes associated with retinal upregulation of trophic factors: observations following optic nerve section. Neuroscience 2004; 126:775-783
• Yu, D.-Y., Cringle, S, Valter, K., Walsh, N., Lee, D., Stone, J. Photoreceptor Death, Trophic Factor Expression, Retinal Oxygen Status And Photoreceptor Function In The P23H Rat: Stress And Protection In A Slow Degeneration. Invest Ophthalmol Vis Sci. 2004 ; 45:2013-2019
• Valter, K., Bisti, S., Stone, J.: Location of CNTFR- on photoreceptor outer segments: evidence of the site of action of CNTF in rat retina. Brain Research 2003; 985:169-175

Book chapters

• Stone, J., Valter,K.: Roles of oxygen in the stability of photoreceptors: evidence from mouse and other models of human disease, In: Eye, retina and visual system of the mouse, Chalupa L.M, Williams, R.W. eds. MIT Press, 2008: 559-572.
• Valter, K., Kirk, DK., Stone, J.: The potential of ambient light restriction to restore function to the degenerating P23H-3 rat retina. In: Advances in Experimental medicine and Biology, Vol.613, Recent Advances in Retinal Degeneration. Anderson, EA., LaVail, MM., Hollyfield, JG.; eds. Springer, US; 2008: 193-199
• Geller, S., Krowka, R., Valter, K., Stone, J.: Toxicity of hyperoxia to the retina: evidence from the mouse. In: Retinal Degenerations. LaVail, MM.; Hollyfield, JG., and Anderson, GA., editors. Kluwer Academic Plenum Publishers; 2006: 425-437
• Stone, J., Mervin, K., Walsh, N., Valter, K., Provis, J. Penfold, P. Photoreceptor Stability and Degeneration in Mammalian Retina: Lessons from the Edge. In Philip L. Penfold, Jan Provis (eds). Macular Degeneration: Science and Medicine in Practice. Springer Verlag; 2005:149-165.
• Stone, J., Valter, K. Roles of retinal macroglia in maintaining the stability of the retina. In: L. Hertz (ed.) Non-Neuronal Cells in the Nervous System: Function and Dysfunction. Amsterdam: Elsevier; 2003:295-314.
• Lee, D.; Geller, S.; Walsh, N.; Valter, K.; Yasumura, D.; Matthes, M.; La Vail, M., Stone, J. Photoreceptor Degeneration in PRO23HIS and S334 Transgenic rats. In:LaVail, MM.; Hollyfield, JG., and Anderson, GA., editors. Retinal Degenerations. Kluwer Academic Plenum Publishers; 2003:297-302.