Ts17, a Tityus serrulatus ß-toxin structurally related to α-scorpion toxins.

Ts17 was purified from the venom of the scorpion Tityus serrulatus, the most dangerous scorpion species in Brazil. The activity on Nav1.1-Nav1.7 channels was electrophysiologically characterized by patch-clamp technique. Ts17 amino acid sequence indicated high similarity to alpha-scorpion toxins; however, it presented beta-toxin activity, altering the kinetics of the Na+-channels. The most affected subtypes during activation (with and without prepulse) and inactivation phases were Nav1.2 and Nav1.5, respectively. For recovery from inactivation, the most affected voltage-gated sodium channel was Nav1.5. Circular dichroism spectra showed that Ts17 presents mainly ß-sheet and unordered structures at all analyzed pHs, and the maximum value of α-helix was found at pH 4.0 (13.3 %). Based on the results, Ts17 might be used as a template to develop a new cardiac drug. Key contribution Purification of Ts17 from Tityus serrulatus, electrophysiological characterization of Ts17 on voltage-gated sodium channel subtypes, ß-toxin classification.

Modulation of hNav by Tst1, a ß-toxin purified from the scorpion Tityus stigmurus.

Scorpion venoms are known as a rich mixture of components, including peptides that can interact with different ion channels, particularly voltage-gated potassium channels (Kv), calcium channels (Cav) and sodium channels (Nav), essential membrane proteins for various physiological functions in organisms. The present work aimed to characterize the modulation of hNa+-channels by Tst1, a peptide purified from the venom of Tityus stigmurus, using whole-cell patch clamp. Tst1 at 100 nM provoked current inhibition in Nav 1.3 (85.23%), Nav 1.2 (67.26%) and Nav 1.4 (63.43%), while Nav 1.1, 1.5, 1.6, and 1.7 were not significantly affected. Tst1 also shifted the voltage of activation and steady-state inactivation to more hyperpolarized states and altered the recovery from inactivation of the channels, reducing repetitive firing of cells, which was more effective in Nav 1.3. Tst1 also demonstrated that the effect on Nav 1.3 is dose-dependent, with an IC50 of 8.79 nM. Taken together, these results confirmed that Tst1, the first Tityus stigmurus NaScTx assayed in relation to Nav channels, is a ß-toxin, as was previously suggested due to its amino acid sequence. KEY CONTRIBUTION: First ß-toxin purified from the venom of Tityus stigmurus scorpion broadly characterized in hNa+-channels.

Slums and pandemics.

How do slums shape the economic and health dynamics of pandemics? A difference-in-differences analysis using millions of mobile phones in Brazil shows that residents of overcrowded slums engaged in less social distancing after the outbreak of Covid-19. We develop and calibrate a choice-theoretic equilibrium model in which individuals are heterogeneous in income and some people live in high-density slums. Slum residents account for a disproportionately high number of infections and deaths and, without slums, deaths increase in non-slum neighborhoods. Policy analysis of reallocation of medical resources, lockdowns and cash transfers produce heterogeneous effects across groups. Policy simulations indicate that: reallocating medical resources cuts deaths and raises output and the welfare of both groups; mild lockdowns favor slum individuals by mitigating the demand for hospital beds, whereas strict confinements mostly delay the evolution of the pandemic; and cash transfers benefit slum residents to the detriment of others, highlighting important distributional effects.

Avoidable environmental disasters and infant health: Evidence from a mining dam collapse in Brazil.

We study the health consequences of one of the largest environmental disasters of the world mining industry, which largely stemmed from regulatory failure. Exploiting the timing and location of the Mariana mine tailings dam collapse in Brazil, we show that in utero exposure to the tragedy significantly reduced birth weight and increased infant mortality. The adverse effects were stronger for infants born to less educated and nonmarried mothers. These findings indicate that poorly enforced environmental regulation may have long-term welfare impacts on local communities.

Cardiac metastasizing leiomyoma: A case report.

INTRODUCTION: Cardiac intracavitary growth of metastasizing tumour is unusual. Benign Metastasizing Leiomyoma (BML) from the uterus to the heart is extremely rare. It affects premenopausal women with a history of uterine leiomyoma. PRESENTATION OF CASE: We report a case of a 42-year-old woman who presented three tumours in the right side of the heart, two years after a hysterectomy due to leiomyomatosis. The cardiac tumours were resected and the diagnosis was uterine leiomyoma. DISCUSSION: The patient developed cardiac failure due to three masses at the right side of the heart. Cardiac involvement in BML is usually asymptomatic and rare. The heart masses were surgically removed and a peri ovarian mass was detected and also removed. Although histologically benign, BML exhibits metastatic qualities. CONCLUSION: It suggests that BML should be included as a differential diagnosis when a female patient presents an intra cardiac mass and a history of hysterectomy.