Crystal structure of the Mycobacterium tuberculosis VirS regulator reveals its interaction with the lead compound SMARt751.

Ethionamide (ETO) is a prodrug that is primarily used as a second-line agent in the treatment of tuberculosis. Among the bacterial ETO activators, the monooxygenase MymA has been recently identified, and its expression is regulated by the mycobacterial regulator VirS. The discovery of VirS ligands that can enhance mymA expression and thereby increase the antimycobacterial efficacy of ETO, has led to the development of a novel therapeutic strategy against tuberculosis. This strategy involves the selection of preclinical candidates, including SMARt751. We report the first crystal structure of the AraC-like regulator VirS, in complex with SMARt751, refined at 1.69 Å resolution. Crystals were obtained via an in situ proteolysis method in the requisite presence of SMARt751. The elucidated structure corresponds to the ligand-binding domain of VirS, adopting an α/ß fold with structural similarities to H-NOX domains. Within the VirS structure, SMARt751 is situated in a completely enclosed hydrophobic cavity, where it forms hydrogen bonds with Asn11 and Asn149 as well as van der Waals contacts with various hydrophobic amino acids. Comprehensive structural comparisons within the AraC family of transcriptional regulators are conducted and analyzed to figure out the effects of the SMARt751 binding on the regulatory activity of VirS.

Two new siderophores produced by Pseudomonas sp. NCIMB 10586: The anti-oomycete non-ribosomal peptide synthetase-dependent mupirochelin and the NRPS-independent triabactin.

Introduction: Globisporangium ultimum is an oomycetal pathogen causing damping-off on over 300 different plant hosts. Currently, as for many phytopathogens, its control relies in the use of chemicals with negative impact on health and ecosystems. Therefore, many biocontrol strategies are under investigation to reduce the use of fungicides. Results: In this study, the soil bacterium Pseudomonas sp. NCIMB 10586 demonstrates a strong iron-repressed in vitro antagonism against G. ultimum MUCL 38045. This antagonism does not depend on the secretion of the broad-range antibiotic mupirocin or of the siderophore pyoverdine by the bacterial strain. The inhibitor molecule was identified as a novel non-ribosomal peptide synthetase (NRPS) siderophore named mupirochelin. Its putative structure bears similarities to other siderophores and bioactive compounds. The transcription of its gene cluster is affected by the biosynthesis of pyoverdine, the major known siderophore of the strain. Besides mupirochelin, we observed the production of a third and novel NRPS-independent siderophore (NIS), here termed triabactin. The iron-responsive transcriptional repression of the two newly identified siderophore gene clusters corroborates their role as iron scavengers. However, their respective contributions to the strain fitness are dissimilar. Bacterial growth in iron-deprived conditions is greatly supported by pyoverdine production and, to a lesser extent, by triabactin. On the contrary, mupirochelin does not contribute to the strain fitness under the studied conditions. Conclusion: Altogether, we have demonstrated here that besides pyoverdine, Pseudomonas sp. NCIMB 10586 produces two newly identified siderophores, namely mupirochelin, a weak siderophore with strong antagonism activity against G. ultimum, and the potent siderophore triabactin.

A Quality Improvement Initiative to Reduce the Need for Mechanical Ventilation in Extremely Low Gestational Age Neonates.

Objective Limiting early intubation and mechanical ventilation in extremely low gestational age neonates (ELGAN) may decrease neonatal morbidity and mortality. The aim of our study was to demonstrate the feasibility, efficacy, and tolerability of a delivery room respiratory management protocol, including delayed umbilical cord clamping (DUCC) in combination with optimized nCPAP with high PEEP levels and less invasive surfactant administration (LISA). Study Design This cohort quality improvement study analyzed the respiratory and neonatal outcomes of all consecutive infants born between 24+0 and 26+6 weeks' gestation before (period 1, n = 40) and after (period 2, n = 52) implementing the new protocol. Results Compared with the period 1 infants, the period 2 infants had a lower rate of intubation in the delivery room (31 vs. 90%, p = 0.001) and were less likely to need mechanical ventilation on day 3 (28 vs. 62%, p = 0.002) and during the hospital stay (75 vs. 92.5%, p < 0.05). The two groups did not differ in terms of mortality or neonatal morbidity. Conclusion A delivery room respiratory management protocol based on DUCC, optimized nCPAP with high PEEP levels, and LISA procedure is both feasible and safe, and improved ELGAN respiratory outcomes.

Congenital lung malformation: evaluation of prenatal and postnatal radiological findings.

BACKGROUND AND OBJECTIVE: This study evaluated the accuracy of prenatal MRI and postnatal CT imaging in the identification of congenital cystic adenomatoid malformation and bronchopulmonary sequestration by comparison with histological analysis. METHODS: Over a 3-year period, 15 patients with lung malformations diagnosed prenatally by ultrasound were referred for prenatal MRI, and all were investigated postnatally by chest CT. All asymptomatic newborns with unresolved lesions underwent elective surgery by thoracoscopy. All surgical specimens were analysed histologically. RESULTS: Among the 15 patients with an abnormality diagnosed by ultrasound, prenatal MRI findings differed from the final histological diagnosis with respect to extent (n = 3), type of lesion (n = 1) and aberrant vessel identification (n = 4). Postnatal chest CT failed to visualize the aberrant vessel in one patient. Complete regression of the lesion was noted in two patients with bronchopulmonary sequestration, and in one patient with congenital cystic adenomatoid malformation and was confirmed by CT. Elective thoracoscopic lobectomy of the affected lobe was performed for 12 patients. Two conversions to thoracotomy were required. All operated patients had an uneventful hospital course. CONCLUSIONS: Prenatal MRI is less accurate than postnatal CT scan, which remains the most reliable diagnostic modality to specify the location and extent and kind of lesions.