According to a Russian-language press release, Trans-Dniester issued new 50- and 200-ruble banknotes with upgraded security features on 15 January 2013. The designs remain unchanged, but the windowed security thread is wider and the date is changed to МОДИФИКАЦИЯ (modified) 2012.
Courtesy of Vadim Tislenko and Vladimir Kozin (http://www.ebay.ca/usr/transnistriabanknotes).