Caracterização de novos peptídeos bloqueadores de canais para K+ isolados da peçonha do escorpião Tityus sp.

Dissertação (mestrado)—Universidade de Brasília, Instituto de Ciências Biológicas, Programa de Pós-Graduação em Biologia Molecular, 2013.As peçonhas escorpiônicas têm sido alvo de pesquisas por possuírem componentes com diversas atividades biológicas, as quais são responsáveis pelas alterações fisiológicas observadas no escorpionismo. Dentre esses componentes, estão as toxinas que agem em canais para potássio (KTxs), as quais têm sido caracterizadas e divididas em subfamílias segundo a sua estrutura primária. O objetivo desta pesquisa foi procurar novas KTxs na peçonha do escorpião colombiano Tityus sp. utilizando duas estratégias: a transcritômica e a proteômica. Uma biblioteca de cDNA foi construída, a partir da glândula de peçonha do escorpião e da sua peçonha foram isoladas e caracterizadas KTxs por cromatografia líquida de alta eficiência (HPLC), espectrometria de massa do tipo MALDI-TOF/TOF e tipo ESI. Os peptídeos isolados foram testados por meio da técnica eletrofisiológica de patch clamp (whole cell). A partir da biblioteca de cDNA, foram caracterizadas cinco sequências precursoras que codificam prováveis KTx: três delas são pertencentes à subfamília α-KTx15, uma à subfamília α-KTx12 e uma à subfamília α-KTx18. Da peçonha, foram sequenciadas outras quatro KTxs com massas moleculares de 2430, 3590, 3640 e 4171 Da. Estas KTxs foram + capazes de diminuir a corrente de K em células do gânglio dorsal de ratos. A caracterização destas novas KTxs reflete o amplo espectro de expressão deste tipo de toxinas e as variadas estratégias moleculares utilizadas pelos escorpiões para produção de componentes neuroativos. ______________________________________________________________________________ ABSTRACTThe venom scorpions have been object of investigations by its different activities biological from components, which are responsible by the physiologic alterations observed in the scorpionism. Within these components, the toxins that target potassium channels (KTxs) are present, which have been characterized and divided according primary structure. The aim was search new KTxs in the Colombian scorpion Tityus sp. venom using two strategies: the transcriptomic and proteomic. The scorpion venom gland a cDNA library was constructed, and from venom, KTxs were characterized using high performance liquid chromatographic (HPLC), mass spectrometry MALDI-TOF/TOF and ESI type technical. The isolated peptides were tested with patch clamp (whole cell) electrophysiological technique. Four precursors likely KTxs were characterized: three α-KTx15, one α-KTx12 and one α-KTx18 like subfamilies. Additionally, four KTxs-like were sequenced from scorpion venom with molecular masses 2430, 3590, 3640 and 4171 Da. These slightly decreased levels potassium current on dorsal root ganglion. The characterization these new KTxs reveals a wide spectrum of KTxs-type toxins and one varied molecular strategy for neuroactive compounds production also

Mortality and pulmonary complications in patients undergoing surgery with perioperative SARS-CoV-2 infection: an international cohort study

Background: The impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on postoperative recovery needs to be understood to inform clinical decision making during and after the COVID-19 pandemic. This study reports 30-day mortality and pulmonary complication rates in patients with perioperative SARS-CoV-2 infection. Methods: This international, multicentre, cohort study at 235 hospitals in 24 countries included all patients undergoing surgery who had SARS-CoV-2 infection confirmed within 7 days before or 30 days after surgery. The primary outcome measure was 30-day postoperative mortality and was assessed in all enrolled patients. The main secondary outcome measure was pulmonary complications, defined as pneumonia, acute respiratory distress syndrome, or unexpected postoperative ventilation. Findings: This analysis includes 1128 patients who had surgery between Jan 1 and March 31, 2020, of whom 835 (74·0%) had emergency surgery and 280 (24·8%) had elective surgery. SARS-CoV-2 infection was confirmed preoperatively in 294 (26·1%) patients. 30-day mortality was 23·8% (268 of 1128). Pulmonary complications occurred in 577 (51·2%) of 1128 patients; 30-day mortality in these patients was 38·0% (219 of 577), accounting for 81·7% (219 of 268) of all deaths. In adjusted analyses, 30-day mortality was associated with male sex (odds ratio 1·75 [95% CI 1·28–2·40], p\textless0·0001), age 70 years or older versus younger than 70 years (2·30 [1·65–3·22], p\textless0·0001), American Society of Anesthesiologists grades 3–5 versus grades 1–2 (2·35 [1·57–3·53], p\textless0·0001), malignant versus benign or obstetric diagnosis (1·55 [1·01–2·39], p=0·046), emergency versus elective surgery (1·67 [1·06–2·63], p=0·026), and major versus minor surgery (1·52 [1·01–2·31], p=0·047). Interpretation: Postoperative pulmonary complications occur in half of patients with perioperative SARS-CoV-2 infection and are associated with high mortality. Thresholds for surgery during the COVID-19 pandemic should be higher than during normal practice, particularly in men aged 70 years and older. Consideration should be given for postponing non-urgent procedures and promoting non-operative treatment to delay or avoid the need for surgery. Funding: National Institute for Health Research (NIHR), Association of Coloproctology of Great Britain and Ireland, Bowel and Cancer Research, Bowel Disease Research Foundation, Association of Upper Gastrointestinal Surgeons, British Association of Surgical Oncology, British Gynaecological Cancer Society, European Society of Coloproctology, NIHR Academy, Sarcoma UK, Vascular Society for Great Britain and Ireland, and Yorkshire Cancer Research

Structural and Functional Analyses of Cone Snail Toxins

Cone snails are marine gastropod mollusks with one of the most powerful venoms in nature. The toxins, named conotoxins, must act quickly on the cone snails´ prey due to the fact that snails are extremely slow, reducing their hunting capability. Therefore, the characteristics of conotoxins have become the object of investigation, and as a result medicines have been developed or are in the trialing process. Conotoxins interact with transmembrane proteins, showing specificity and potency. They target ion channels and ionotropic receptors with greater regularity, and when interaction occurs, there is immediate physiological decompensation. In this review we aimed to evaluate the structural features of conotoxins and the relationship with their target types