Potential in vitro action of an adenosine analog and synergism with penicillin against Corynebacterium pseudotuberculosis.

Caseous lymphadenitis is a well-known disease caused by Corynebacterium pseudotuberculosis affecting small ruminants with small significance to human health because of its minor zoonotic potential. In both cases, few treatment options are available and conventional antimicrobial therapy is commonly refractory due to development of pyogranulomatous reactions, bringing great interest in discovering novel therapeutics for more suitable approaches. Dideoxynucleotides presented antibacterial action against various bacteria but were never described for C. pseudotuberculosis. Hypothesizing the antimicrobial action of 2',3'-dideoxiadenosine (ddATP) against C. pseudotuberculosis, we performed for the first time an investigation of its minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) in the ATCC® 19,410 strain and a well-characterized clinical isolate of C. pseudotuberculosis. We also assessed potential synergism with penicillin. ddATP showed a growth delay effect for C. pseudotuberculosis at 2 µmol/mL and a MIC and MBC of 4 µmol/mL against the ATCC® 19,410 strain, but not for the clinical strain. An antimicrobial effect was observed when using concentrations lower than the MIC of ddATP associated with penicillin for both strains tested. Our data suggest the potential of nucleotide analogs, especially adenosine, and its combination with penicillin, as a possible novel treatment for C. pseudotuberculosis-induced infections, and contributes with knowledge regarding alternative drugs to treat C. pseudotuberculosis infections.

Learning curve for the laparoscopy-guided kidney biopsy procedure in small corpses of dogs and pigs.

The use of renal biopsy through laparoscopy is increasingly present both in human and veterinary medicine. However, both techniques require skill and training to make the operator capable to do it. The learning curve allows the quantitative and qualitative assessment of the number of attempts and minimum time for the surgical procedure. The objective included establish the learning curve for laparoscopy-guided kidney biopsy procedures in dog and pig corpses. Six dogs and six pigs corpses weighing less than 10 kg were used for this study. All corpses underwent kidney biopsy performed through laparoscopy. Twenty-four operators, two per animal, performed 20 renal biopsies each (10 for each kidney), with 480 collection-procedures in total. Duration and difficulty of the procedure and the biopsy sample quality were evaluated and statistical analysis was performed using a mixed regression model with a random effect of individuals and multivariate analysis of data. There were 91.5% of the samples that were adequate for evaluation. There was no significant difference in the number of glomeruli or cortex percentage considering the attempts in either species, demonstrating the operator's ability since first collection. Swine samples showed higher amounts of renal cortex than canine samples. The procedure duration was shorter as more attempts were performed in dogs and pigs. From the fourth repetition, the professional reached a plateau for the variable related to 'collection', and from the second, the professional presented uniform duration for 'sample storage'. Operators of the swine model acquired more agility than the dog ones. The variable 'difficulty' decreased as more repetitions were performed, reaching a plateau in the sixth attempt. Seven renal biopsies laparoscopy-guided are required for an operator to be considered 'capable' to perform the procedure in the referred species included. The learning curve for image-guided kidney biopsy procedures improves the implementation of this technique and benefits patients that undergo this procedure.

Positive effects of antitumor drugs in combination with propolis on canine osteosarcoma cells (spOS-2) and mesenchymal stem cells.

The combination of lower concentrations of antitumor drugs (carboplatin - CARB, doxorubicin - DOX, and methotrexate - MET) with propolis was investigated against canine osteosarcoma (spOS-2) and mesenchymal stem cells (MSC) in vitro. The mechanism of action in the combinations was analyzed. spOS-2 cells were incubated up to 72 h with propolis (50 µg/ml) alone or in combination with CARB (10-400 µmol/l), DOX (0.5-2 µmol/l) or MET (50-200 µmol/l). Cell viability was assessed by MTT assay, apoptosis/necrosis by flow cytometry, and MSC was incubated with the optimum combination. Propolis alone exerted no cytotoxic action against spOS-2 cells, whereas CARB (400, 200 and 100 µmol/l) exhibited the highest cytotoxic effects comparing to DOX and MET. The combination of propolis with the lowest concentrations of CARB led to better results comparing to CARB alone, which was not observed using DOX and MET. Apoptosis was involved in the action of propolis + CARB in spOS-2 cells. MSC were not affected by CARB/propolis, indicating that the cytotoxic action of the combination was specific to tumor cells but not to normal ones. Propolis improved the action of CARB against spOS-2 cells using lower concentrations of this drug, without affecting MSC. These findings are relevant and indicate a possible application of propolis in OSA treatment.