Activity of silver nanoparticles on prokaryotic cells and Bothrops jararacussu snake venom.

Nanoparticle-conjugated venom-toxins of venomous animals and its therapeutic efficacy against emerging or neglecting diseases is a promising strategy. In this study, silver nanoparticles (AgNPs ∼50 nm, 0.081 mg mL-1) were studied against the neuromuscular blockade, myotoxic effects induced by Bothrops jararacussu venom (60 µg mL-1) and also against prokaryotic cells. The neurotoxicity was evaluated on ex vivo mouse phrenic nerve-diaphragm using traditional myographic technique, able to obtain functional contractile responses and to check the neurotransmission. The myotoxicity on mammalian cells was evaluated in muscles resulting from pharmacological assays using routine histological techniques and light microscopy. The toxicity to prokaryotic cells was evaluated on Salmonella typhimurium TA100 without metabolic activation. The in vitro preincubation model between AgNPs and venom was enough to abolish toxic effects of B. jararacussu venom, but mammalian cells were highly sensitive to AgNPs more than prokaryotic cells, by acting as dose-independently and dose-dependently parameters, respectively. These results allowed us to conclude that AgNPs showed promising activity as antivenom agent but for its safer use, the toxicity should be evaluated on experimental animals.

Are Silver Nanoparticles Useful for Treating Second-Degree Burns? An Experimental Study in Rats.

Purpose: In this work, the potential usefulness of silver nanoparticles (AgNPs) for treating burn wounds was examined. Methods: Second-degree burns were induced in male Wistar rats by touching the skin with a heated (70°C) metallic device for 10 s, after which the animals were randomly allocated to one of two groups: control (n=8, treated with sterile saline) and experimental (n=8, treated with AgNPs, 0.081 mg/mL; 50 µL applied to the burn surface). Seven, 14, 21 and 28 days after lesion induction two rats from each group were killed and blood samples were collected for a complete blood count and to assess oxidative stress. The livers were examined macroscopically and skin samples were collected for histological analysis. Results: Macroscopically, wound healing and skin remodeling in the experimental group were similar to the saline-treated rats. Likewise, there were no significant differences in the histological parameters between the two groups. However, treatment with AgNPs caused a persistent reduction in white blood cell (WBC) counts throughout the experiment, whereas platelet counts increased on days 7 and 28 but decreased on days 14 and 21; there was also an increase in the blood concentration of reduced glutathione on day 7 followed by a decrease on days 21 and 28. There were no significant changes in blood glutathione peroxidase (GSH-Px) and catalase (CAT) activities or in the serum concentration of thiobarbituric acid reactive substances. Conclusion: The findings of this study raise questions about the potential transitory effects of AgNPs based on the changes in WBC and platelet counts, blood glutathione concentrations and macroscopic hepatic alterations.

Neutralising ability of Terminalia fagifolia extract (Combretaceae) against the in vitro neuromuscular effects of Bothrops jararacussu venom.

The ability of Terminalia fagifolia hydroalcoholic extract (Tf-HE) to neutralise the paralysis and myotoxicity induced by Bothrops jararacussu venom was assayed using mouse phrenic nerve-diaphragm (PND) preparation and two varieties of chick biventer cervicis (BC) preparations. Tf-HE 100 µg/mL and 500 µg/mL were tested against 40 and 200 µg of venom/mL in PND and BC preparations, respectively, using pre- and post-venom incubation treatments. The effects of Tf-HE against the myotoxicity caused by venom were evaluated via histological analysis (PND) and creatine kinase (CK) release (BC). Tf-HE was able to reverse the venom paralysis in both preparation types. The contractures to exogenous ACh in BC preparations showed that Tf-HE may act on extrinsic, preserving those intrinsic postsynaptic receptors. There was a positive correlation between CK and morphological changes. The high non-hemolytic saponin content can explain the Tf-HE efficacy against the toxic effects of B. jararacussu venom in vertebrate neuromuscular preparations.

Teratologia do aparelho branquial e outras estruturas céfalo-cevicais / Teratology of branchial region and other head-neck structures

Os autores procederam a uma revisão bibliográfica, contemplando a descrição de defeitos congênitos e síndromes que afetam a organogênese do aparelho branquial e outras estruturas céfalo-cervicais