RESUMO
The genomic comparison of two Klebsiella michiganensis clinical isolates recovered from the same patient, one resistant to piperacillin-tazobactam and intermediate to cefotaxime, the other resistant to ceftazidime but susceptible to piperacillin-tazobactam, revealed one mutation in the blaOXY-1-24 gene accounting for a L169M substitution in the Ω loop. Cloning experiment in Escherichia coli demonstrated the contribution of this mutation to the hydrolysis spectrum extension towards ceftazidime and cefepime, whereas the resistance to piperacillin-tazobactam was reduced. To the best of our knowledge, this study shows for the first time that ceftazidime resistance can occur in vivo from OXY-1 precursor by structural alteration.
RESUMO
In the crystal structure of the title compound, {[Co(C11H9NSO5)(C10H9N3)]0.5C3H7NO·H2O} n or {[Co(dmtb)(dpa)]·0.5DMF·H2O} n (dmtb2- = 5-[(di-meth-yl-amino)-thioxometh-oxy]-1,3-benzene-dicarboxyl-ate and dpa = 4,4'-di-pyridyl-amine), an assembly of periodic [Co(C11H9NSO5)(C10H9N3)] n layers extending parallel to the bc plane is present. Each layer is constituted by distorted [CoO4N2] octa-hedra, which are connected through the µ 2-coordination modes of both dmtb2- and dpa ligands. Occupationally disordered water and di-meth-yl-formamide (DMF) solvent mol-ecules are located in the voids of the network to which they are connected through hydrogen-bonding inter-actions.
RESUMO
In the title complex, [ZnCl2(C14H12N2O2)], the ZnII atom is located on a twofold rotation axis and is fourfold coordinated by two chlorido ligands and a bidentate 4,7-meth-oxy-1,10-phenanthroline ligand in a distorted tetra-hedral environment. Weak π-π stacking inter-actions between adjacent 4,7-dimeth-oxy-1,10-phenanthroline rings [centroid-to-centroid distances = 3.5969â (11) and 3.7738â (11)â Å] contribute to the alignment of the complexes in layers parallel to (01).
RESUMO
Bradykinin-potentiating peptides from Bothrops jararaca (Bj) discovered in the early 1960s, were the first natural inhibitors of the angiotensin-converting enzyme (ACE). These peptides belong to a large family of snake venom proline-rich oligopeptides (PROs). One of these peptides, Bj-PRO-9a, was essential for defining ACE as effective drug target and development of captopril, an active site-directed inhibitor of ACE used worldwide for the treatment of human arterial hypertension. Recent experimental evidences demonstrated that cardiovascular effects exerted by different Bj-PROs are due to distinct mechanisms besides of ACE inhibition. In the present work, we have investigated the cardiovascular actions of four Bj-PROs, namely Bj-PRO-9a, -11e, -12b and -13a. Bj-PRO-9a acts upon ACE and BK activities to promote blood pressure reduction. Although the others Bj-PROs are also able to inhibit the ACE activity and to potentiate the BK effects, our results indicate that antihypertensive effect evoked by them involve new mechanisms. Bj-PRO-11e and Bj-PRO-12b involves induction of [Ca(2+)]i transients by so far unknown receptor proteins. Moreover, we have suggested argininosuccinate synthetase and M3 muscarinic receptor as targets for cardiovascular effects elicited by Bj-PRO-13a. In summary, the herein reported results provide evidence that Bj-PRO-mediated effects are not restricted to ACE inhibition or potentiation of BK-induced effects and suggest different actions for each peptide for promoting arterial pressure reduction. The present study reveals the complexity of the effects exerted by Bj-PROs for cardiovascular control, opening avenues for the better understanding of blood pressure regulation and for the development of novel therapeutic approaches.