The influence of type I diabetes mellitus in periodontal disease induced changes of the gingival epithelium and connective tissue.

Periodontal disease constitutes the most frequent chronic diseases in human dentition. Bacterial plaque is the main etiologic agent, although it is the host immune response that causes periodontal tissue destruction. Diabetes is considered an important risk factor, not only for the onset but also for progression of the disease. The aim of this study was to analyze structural changes in the rat gingival epithelium and connective tissue in response to the experimental periodontal disease induced by the ligature technique, under the influence of diabetes. The results showed that experimental periodontal disease is characterized by marked inflammation, affecting both the epithelial and connective tissues, causing degeneration of the dermal papilla, increase in the number of inflammatory cells, destruction of reticulin fibers, and accumulation of dense collagen fibers (fibrosis). These changes were worsened by diabetes, apparently by hampering the inflammatory response and affecting tissue repair of the affected tissues.

Leishmania replication protein A-1 binds in vivo single-stranded telomeric DNA.

Replication protein A (RPA) is a highly conserved heterotrimeric single-stranded DNA-binding protein involved in different events of DNA metabolism. In yeast, subunits 1 (RPA-1) and 2 (RPA-2) work also as telomerase recruiters and, in humans, the complex unfolds G-quartet structures formed by the 3' G-rich telomeric strand. In most eukaryotes, RPA-1 and RPA-2 bind DNA using multiple OB fold domains. In trypanosomatids, including Leishmania, RPA-1 has a canonical OB fold and a truncated RFA-1 structural domain. In Leishmania amazonensis, RPA-1 alone can form a complex in vitro with the telomeric G-rich strand. In this work, we show that LaRPA-1 is a nuclear protein that associates in vivo with Leishmania telomeres. We mapped the boundaries of the OB fold DNA-binding domain using deletion mutants. Since Leishmania and other trypanosomatids lack homologues of known telomere end binding proteins, our results raise questions about the function of RPA-1 in parasite telomeres.