Deciphering the structural basis for glucocorticoid resistance caused by missense mutations in the ligand binding domain of glucocorticoid receptor.

The glucocorticoid resistance hereditary condition may emerge from the occurrence of point mutations in the glucocorticoid receptor (GR), which could impair its functionality. Because the main feature of such pathology is the resistance of the hypothalamic-pituitary-adrenal axis to the hormone cortisol, we used the GR ligand binding domain three-dimensional structure to perform computational analysis for eight variants known to cause this clinical condition (I559 N, V571A, D641V, G679S, F737L, I747 M, L753F and L773P), aiming to understand, on the atom scale, how they cause glucocorticoid resistance. We observed that the mutations generated a reduced affinity to cortisol and they alter some loop conformations, which could be a consequence from changes in protein motion, which in turn could result from the reduced stability of mutant GR structures. Therefore, the analyzed mutations compromise the GR ligand binding domain structure and cortisol binding, which could characterize the glucocorticoid resistance phenotype.

ß-Lactamase inhibitor peptides as the new strategies to overcome bacterial resistance.

Bacterial resistance has become a problem of great concern all over the world. Gram-negative bacteria, including the Enterobacteriaceae family and Pseudomonas and Acinetobacter species, are among the leading causes of healthcare-associated infections. The rate of antibiotic resistance among these pathogens has increased dramatically in recent years, reaching a pandemic scale. The most common mechanism of resistance described for Gram-negative bacteria consists of beta-lactamase production. These enzymes hydrolyze beta-lactam antibiotics, which are among the most commonly used antimicrobial agents. As with other antibiotics, reports of bacterial resistance to these agents have increased in recent years. An alternative method for combating beta-lactamasemediated resistance has been the use of small beta-lactamase inhibitors (e.g., clavulanic acid and tazobactam), allowing the resurgence of beta-lactam antibiotics for the treatment of infections caused by beta-lactamase-producing bacteria. However, due to the beta-lactamase group's diversity, some of them present resistance to conventional beta-lactamase inhibitors. Bearing this in mind, in the last two decades, beta- lactamase inhibitor peptides have been developed as alternative adjuvants to strike back against such strains. In this review, we outline the most recent findings related to the design of beta-lactamase inhibitor peptides and their biotechnological potential.

Computational tools for exploring sequence databases as a resource for antimicrobial peptides.

Data mining has been recognized by many researchers as a hot topic in different areas. In the post-genomic era, the growing number of sequences deposited in databases has been the reason why these databases have become a resource for novel biological information. In recent years, the identification of antimicrobial peptides (AMPs) in databases has gained attention. The identification of unannotated AMPs has shed some light on the distribution and evolution of AMPs and, in some cases, indicated suitable candidates for developing novel antimicrobial agents. The data mining process has been performed mainly by local alignments and/or regular expressions. Nevertheless, for the identification of distant homologous sequences, other techniques such as antimicrobial activity prediction and molecular modelling are required. In this context, this review addresses the tools and techniques, and also their limitations, for mining AMPs from databases. These methods could be helpful not only for the development of novel AMPs, but also for other kinds of proteins, at a higher level of structural genomics. Moreover, solving the problem of unannotated proteins could bring immeasurable benefits to society, especially in the case of AMPs, which could be helpful for developing novel antimicrobial agents and combating resistant bacteria.

An anti-infective synthetic peptide with dual antimicrobial and immunomodulatory activities.

Antibiotic-resistant infections are predicted to kill 10 million people per year by 2050, costing the global economy $100 trillion. Therefore, there is an urgent need to develop alternative technologies. We have engineered a synthetic peptide called clavanin-MO, derived from a marine tunicate antimicrobial peptide, which exhibits potent antimicrobial and immunomodulatory properties both in vitro and in vivo. The peptide effectively killed a panel of representative bacterial strains, including multidrug-resistant hospital isolates. Antimicrobial activity of the peptide was demonstrated in animal models, reducing bacterial counts by six orders of magnitude, and contributing to infection clearance. In addition, clavanin-MO was capable of modulating innate immunity by stimulating leukocyte recruitment to the site of infection, and production of immune mediators GM-CSF, IFN-γ and MCP-1, while suppressing an excessive and potentially harmful inflammatory response by increasing synthesis of anti-inflammatory cytokines such as IL-10 and repressing the levels of pro-inflammatory cytokines IL-12 and TNF-α. Finally, treatment with the peptide protected mice against otherwise lethal infections caused by both Gram-negative and -positive drug-resistant strains. The peptide presented here directly kills bacteria and further helps resolve infections through its immune modulatory properties. Peptide anti-infective therapeutics with combined antimicrobial and immunomodulatory properties represent a new approach to treat antibiotic-resistant infections.

Pyrazine functionalized Ag(I) and Au(I)-NHC complexes are potential antibacterial agents.

Antimicrobial resistance is an ever-increasing problem throughout the world and has already reached severe proportions. Bacteria can develop ways to render traditional antibiotics ineffective, raising a crucial need to find new antimicrobials with novel mode of action. We demonstrate here a novel class of pyrazine functionalized Ag(I) and Au(I)-NHC complexes as antibacterial agents against human pathogens that are resistant to several antibiotics. Complete synthetic and structural studies of Au(I) and Ag(I) complexes of 2-(1-methylimidazolium) pyrimidinechloride (L-1), 2,6-bis(1-methylimidazol)pyrazinechloride (L-2) and 2,6-bis(1-methyl imidazol) pyrazinehexa-fluorophosphate (L-3) are reported herein. Chloro[2,6-bis(1-methyl imidazol)pyrazine]gold(I), 2b and chloro [2,6-bis(1-methyl imidazol)pyrazine]silver(I), 2a complexes are found to have more potent antimicrobial activity than other synthesized compounds and several conventionally used antibiotics. Complexes 2b and 2a also inhibit the biofilm formation by Gram-positive bacteria, Streptococcus mutans and Gram-negative bacteria, Escherichia coli, causing drastic damage to the bacterial cell wall and increasing membrane permeability. Complexes 2b and 2a strongly binds to both Lys and Dap-Type peptidoglycan layers, which may be the reason for damage to the bacterial cell wall. Theoretical studies of all the complexes reveal that 2b and 2a are more reactive than other complexes, and this may be the cause of differences in antibacterial activity. These findings will pave the way towards developing a new class of antibiotics against different groups of conventional antibiotic-resistant bacteria.

[Embolization--a new concept in the treatment of esophageal varices (late results)]. / Embolização--uma nova conceituação no tratamento das varizes esofágicas (resultados tardios).

Although since 1978 we have been applying this new technique, we awaited the late results to evaluate with security the value of its application. As we have previously described in a short communication, in 1979, to embolizate the esophageal bleeding varices, we use a laparotomic approach through the right gastric vein to inject the embolizating material. After five years applying this technique, the results confirmed its efficacy.

[Treatment of bleeding esophageal varices by embolization of the left gastric vein. (Preliminary note) (author's transl)]. / Tratamento das varizes sangrantes do esôfago por embolização da veia gástrica esquerda. (Nota prévia).

The author reports eleven cases of embolization of the left gastric vein in patients with esophageal varices due to schistosomotic hepatic fibrosis. The technique of the procedure is briefly described. The results have been favourable and no recurrence of bleeding was observed so far.