Re(I) and Tc(I) Complexes for Targeting Nitric Oxide Synthase: Influence of the Chelator in the Affinity for the Enzyme

Aiming to design ^99mTc complexes for probing nitric oxide synthase (NOS) by SPECT, we synthesized conjugates ( L4 – L6 ) comprising a NOS‐recognizing moiety connected to a diamino‐propionic acid (dap) chelating unit. The conjugates led to complexes of the type fac‐[M(CO)₃(?³‐L)] (M = Re/^99mTc; Re4 / Tc4 : L =  L4 ; Re5 / Tc5 : L =  L5 ; Re6 / Tc6 : L =  L6 ). Enzymatic studies showed that L4 and L5 , but not L6 , gave complexes ( Re4 and Re5 ) that are less potent than the conjugates. To rationalize these results, we performed docking and molecular dynamics simulations. The high affinity of L4 and L5 is due to the strong interactions between the dap chelator and polar residues of the binding cavity. These interactions are hampered by metallation resulting in complexes with lower affinity. The higher potency of Re5 compared to Re4 was assigned to the increased bulkiness of Re5 and the presence of additional anchoring groups that better fit the active site and provide more extensive contacts. In turn, Re6 is too bulky and its organometallic tail is oriented toward the peripheral pocket of iNOS, leading to loss of contacts and a lower affinity. These results were compared with our previous results obtained with analogue complexes stabilized by a pyrazolyl‐diamine chelating unit.     

Loading deproteinized bovine bone with strontium enhances bone regeneration in rat calvarial critical size defects

Clinical Oral Investigations - To evaluate the effect of grafting with strontium (Sr)-loaded deproteinized bovine bone (DBB) on bone healing in calvarial critical size defects (CSD) in rats. Two...     

Consenso sobre Ecocardiografia Transesofágica Perioperatória da Sociedade Brasileira de Anestesiologia e do Departamento de Imagem Cardiovascular da Sociedade Brasileira de Cardiologia

Through the Life Cycle of Intraoperative Transesophageal Echocardiography (ETTI/SBA) the Brazilian Society of Anesthesiology, together with the Department of Cardiovascular Image of the Brazilian Society of Cardiology (DIC/SBC), createded a task force to standardize the use of intraoperative transesophageal echocardiography by Brazilian anesthesiologists and echocardiographers based on scientific evidence from the Society of Cardiovascular Anesthesiologists/American Society of Echocardiography (SCA/ASE) and the Brazilian Society of Cardiology.     

Positive troponin T in a chagasic patient with sustained ventricular tachycardia and no obstructive lesions on cine coronary angiography

The assessment and stratification of patients with chest pain in the emergency unit may indicate the appropriate therapy for each patient based on the probability of the presence of acute coronary artery disease and on the risk of its major cardiac events. That assessment is based on the triplet: clinical setting, electrocardiographic findings, and markers of myocardial lesion. We report the case of a 58-year-old male chagasic patient admitted to the emergency unit due to chest pain and palpitations, with an electrocardiogram showing sustained ventricular tachycardia and positive troponin measurement (0.99 ng/mL). The patient underwent cine coronary angiography, which evidenced no obstructive coronary artery disease.