Mariana Agustinho Rodrigues

Rat atrial responses to Bothrops jararacussu (jararacuçu) snake venom.

Envenoming by the pitviper Bothrops jararacussu produces cardiovascular alterations, including coagulopathy, systemic hemorrhage, hypotension, circulatory shock and renal failure. In this work, we examined the activity of this venom in rat isolated right atria. Incubation with venom (0.025, 0.05, 0.1 and 0.2mg/ml) caused concentration-dependent muscle contracture that was not reversed by washing. Muscle damage was seen histologically and confirmed by quantification of creatine kinase-MB (CK-MB) release. Heating and preincubation of venom with p-bromophenacyl bromide (a phospholipase A2 inhibitor) abolished the venom-induced contracture and muscle damage. In contrast, indomethacin, a non-selective inhibitor of cyclooxygenase, and verapamil, a voltage-gated Ca(2+) channel blocker, did not affect the responses to venom. Preincubation of venom with Bothrops or Bothrops/Crotalus antivenom or the addition of antivenom soon after venom attenuated the venom-induced changes in atrial function and tissue damage. These results indicate that B. jararacussu venom adversely affected rat atrial contractile activity and muscle organization through the action of venom PLA2; these venom-induced alterations were attenuated by antivenom.

Strain gauges's analysis on implant-retained prosthesis' cast accuracy.

INTRODUCTION A proper cast is essential for a successful rehabilitation with implant prostheses, in order to produce better structures and induce less strain on the implants. AIMS The aim of this study was to evaluate the precision of four different mold filling techniques and verify an accurate methodology to evaluate these techniques. MATERIALS AND METHODS A total of 40 casts were obtained from a metallic matrix simulating three unit implant-retained prostheses. The molds were filled using four different techniques in four groups (n = 10): Group 1 - Single-portion filling technique; Group 2 - Two-step filling technique; Group 3 - Latex cylinder technique; Group 4 - Joining the implant analogs previously to the mold filling. A titanium framework was obtained and used as a reference to evaluate the marginal misfit and tension forces in each cast. Vertical misfit was measured with an optical microscope with an increase of 120 times following the single-screw test protocol. Strain was quantified using strain gauges. Data were analyzed using one-way ANOVA (Tukeys test) (α =0.05). The correlation between strain and vertical misfit was evaluated by Pearson test. RESULTS The misfit values did not present statistical difference (P = 0.979), while the strain results showed statistical difference between Groups 3 and 4 (P = 0.027). CONCLUSIONS The splinting technique was considered to be as efficient as the conventional technique. The strain gauge methodology was accurate for strain measurements and cast distortion evaluation. There was no correlation between strain and marginal misfit.