In vivo evaluation of a metronidazole-containing gel for the adjuvant treatment of chronic periodontitis: preliminary results

The present study developed an experimental metronidazole-based gel and evaluated its efficacy for the adjuvant treatment of chronic periodontitis. Sixteen patients were randomly allocated into two groups of eight subjects according to the following proposed treatments: (1) scaling and root planing (active control) or (2) scaling and root planing and direct periodontal intrapocket application of 15% metronidazole-based gel in two sites (a parts per thousand yen5 mm in depth) (experimental group). Potential changes in the subgingival microbiota were assessed using a DNA Checkerboard method at three proposed times: baseline and following 7 or 30 days of drug administration. High-performance liquid chromatography (HPLC) monitored metronidazole concentrations in the crevicular fluid during treatment. The metronidazole experimental group presented lower bacterial counts than the control group at the three evaluated times (p < 0.01 for baseline, p < 0.001 for 7 or 30 days) when the target species were analyzed as a pool of bacteria. Samples revealed significantly lower counts 7 days after drug administration compared with baseline or after 30 days (p < 0.05). HPLC analysis detected gel 1 h after application. The metronidazole-based gel significantly decreased the total bacterial count at the three evaluated times. Periodontopathogenic species were not different after gel administration.

The Natural Cell-Penetrating Peptide Crotamine Targets Tumor Tissue in Vivo and Triggers a Lethal Calcium-Dependent Pathway in Cultured Cells

Our goal was to demonstrate the in vivo tumor specific accumulation of crotamine, a natural peptide from the venom of the South American rattlesnake Crotalus durissus terrificus, which has been characterized by our group as a cell penetrating peptide with a high specificity for actively proliferating cells and with a concentration-dependent cytotoxic effect. Crotamine cytotoxicity has been shown to be dependent on the disruption of lysosomes and subsequent activation of intracellular proteases. In this work, we show that the cytotoxic effect of crotamine also involves rapid intracellular calcium release and loss of mitochondrial membrane potential as observed in real time by confocal microscopy. The intracellular calcium overload induced by crotamine was almost completely blocked by thapsigargin. Microfluorimetry assays confirmed the importance of internal organelles, such as lysosomes and the endoplasmic reticulum, as contributors for the intracellular calcium increase, as well as the extracellular medium. Finally, we demonstrate here that crotamine injected intraperitoneally can efficiently target remote subcutaneous tumors engrafted in nude mice, as demonstrated by a noninvasive optical imaging procedure that permits in vivo real-time monitoring of crotamine uptake into tumor tissue. Taken together, our data indicate that the cytotoxic peptide crotamine can be used potentially for a dual purpose: to target and detect growing tumor tissues and to selectively trigger tumor cell death.