Isolation of Salmonella mutants resistant to the inhibitory effect of Salicylidene acylhydrazides on flagella-mediated motility.

Salicylidene acylhydrazides identified as inhibitors of virulence-mediating type III secretion systems (T3SSs) potentially target their inner membrane export apparatus. They also lead to inhibition of flagellar T3SS-mediated swimming motility in Salmonella enterica serovar. Typhimurium. We show that INP0404 and INP0405 act by reducing the number of flagella/cell. These molecules still inhibit motility of a Salmonella ΔfliH-fliI-fliJ/flhB((P28T)) strain, which lacks three soluble components of the flagellar T3S apparatus, suggesting that they are not the target of this drug family. We implemented a genetic screen to search for the inhibitors' molecular target(s) using motility assays in the ΔfliH-fliI/flhB((P28T)) background. Both mutants identified were more motile than the background strain in the absence of the drugs, although HM18 was considerably more so. HM18 was more motile than its parent strain in the presence of both drugs while DI15 was only insensitive to INP0405. HM18 was hypermotile due to hyperflagellation, whereas DI15 was not hyperflagellated. HM18 was also resistant to a growth defect induced by high concentrations of the drugs. Whole-genome resequencing of HM18 indicated two alterations within protein coding regions, including one within atpB, which encodes the inner membrane a-subunit of the F(O)F(1)-ATP synthase. Reverse genetics indicated that the alteration in atpB was responsible for all of HM18's phenotypes. Genome sequencing of DI15 uncovered a single A562P mutation within a gene encoding the flagellar inner membrane protein FlhA, the direct role of which in mediating drug insensitivity could not be confirmed. We discuss the implications of these findings in terms of T3SS export apparatus function and drug target identification.Funding: IMA and XL were supported by Wellcome Trust Project Grant 088266 to IMA and AJB. AKJV was funded by an E.C. Marie Curie postdoctoral fellowship (MEIF-CT-2005-023694) and an EMBO short-term fellowship (244-2007). XL was supported additionally by Wellcome Trust Project Grant 088231 to AJB and KN. DR was supported by a University of Bristol Centenary Postgraduate Studentship. This work was also supported in part by MRC project grants G0701243 and MR-J002097-1 to AJB and AJB and KN, respectively, and by Grants-in-Aid for Scientific Research (22570161 and 23121516 to TM, and 21227006 to KN) and Targeted Proteins Research Program from the Ministry of Education, Culture, Sports, Science and Technology of Japan and by Takeda Science Foundation (to TM). YVM is a Research Fellow of the Japanese Society for the Promotion of Science. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Isolated congenital tracheal stenosis in a preterm newborn

Severe tracheal stenosis, resulting in functional atresia of the trachea is a rare congenital malformation with an estimated occurrence of two in 100,000 newborns. If no esophagotracheal fistula is present to allow for spontaneous breathing, this condition is usually fatal. We report on a male infant born at 32 weeks of gestation. The patient presented with respiratory distress immediately after delivery due to severe congenital tracheal stenosis resulting in functional atresia of the trachea. Endotracheal intubation failed and even emergency tracheotomy did not allow ventilation of the patient lungs. The patient finally succumbed to prolonged hypoxia due to functional tracheal atresia. The etiology of tracheal atresia and tracheal stenosis is still unclear, but both conditions are frequently combined with other anomalies of the VACTERL (vertebral anomalies, anal atresia, cardiovascular anomalies, tracheoesophageal fistula, esophageal atresia, renal/radial anomalies and limb defects) and TACRD (tracheal agenesis, cardiac, renal and duodenal malformations) association. Conclusion Successful treatment of severe congenital tracheal stenosis and tracheal atresia depends on either prenatal diagnosis or recognition of this condition immediately after birth to perform tracheotomy without delay. Nevertheless, despite any efforts, the therapeutical results of severe tracheal stenosis and tracheal atresia are still unsatisfactory

Surfactant replacement and open lung concept – Comparison of two treatment strategies in an experimental model of neonatal ARDS

Background: Several concepts of treatment in neonatal ARDS have been proposed in the last years. The present study compared the effects of open lung concept positive pressure ventilation (PPVOLC) with a conventional ventilation strategy combined with administration of two different surfactant preparations on lung function and surfactant homoeostasis. Methods: After repeated whole-lung saline lavage, 16 newborn piglets were assigned to either PPVOLC(n = 5) or surfactant treatment under conventional PPV using a natural bovine (n = 5) or a monomeric protein B based surfactant (n = 6). Results: Comprehensive monitoring showed each treatment strategy to improve gas exchange and lung function, although the effect on PaO2and pulmonary compliance declined over the study period in the surfactant groups. The overall improvement of the ventilation efficiency index (VEI) was significantly greater in the PPVOLCgroup. Phospholipid and protein analyses of the bronchoalveolar lavage fluid showed significant alterations to surfactant homoeostasis in the PPVOLCgroup, whereas IL-10 and SP-C mRNA expression was tendentially increased in the surfactant groups. Conclusion: The different treatment strategies applied could be shown to improve gas exchange and lung function in neonatal ARDS. To which extent differences in maintenance of lung function and surfactant homeostasis may lead to long-term consequences needs to be studied further

Clinical practice: neonatal resuscitation. A Dutch consensus

The updated Dutch guidelines on Neonatal Resuscitation assimilate the latest evidence in neonatal resuscitation. Important changes with regard to the 2004 guidelines and controversial issues concerning neonatal resuscitation are reviewed, and recommendations for daily practice are provided and argued in the context of the ILCOR 2005 consensus

Open lung ventilation preserves the response to delayed surfactant treatment in surfactant-deficient newborn piglets

OBJECTIVE: Delayed surfactant treatment (>2 hrs after birth) is less effective than early treatment in conventionally ventilated preterm infants with respiratory distress syndrome. The objective of this study was to evaluate if this time-dependent efficacy of surfactant treatment is also present during open lung ventilation. DESIGN: Prospective, randomized controlled animal study. SETTING: University-affiliated research laboratory. SUBJECTS: Thirty-eight newborn piglets. INTERVENTIONS: Following repeated whole-lung lavage, animals were randomly allocated to conventional positive pressure ventilation (PPVCON) using a positive end-expiratory pressure (PEEP) of 5 cm H2O and a tidal volume of 7 mL/kg or open lung positive pressure ventilation (PPVOLV). During PPVOLV, collapsed alveoli were actively recruited and thereafter stabilized with sufficient PEEP. Within each ventilation group, animals received surfactant (25 mg/kg) either after 2 hrs (PPVCON-2 and PPVOLV-2) or after 4 hrs (PPVCON-4 and PPVOLV-4) of ventilation. A control group received surfactant immediately after lung lavage. Following surfactant administration, all animals were conventionally ventilated for an additional 2 hrs. MEASUREMENTS AND MAIN RESULTS: Two hours after surfactant treatment, both oxygenation and lung mechanics showed a clear deterioration in the PPVCON-4 group compared with PPVCON-2 and the control group. However, this deterioration of the surfactant response over time was not observed during PPVOLV. Analysis of the bronchoalveolar lavage fluid obtained at the end of the experiment showed that the protein concentration and the conversion of large to small aggregate surfactant was significantly higher in the PPVCON-4 group compared with the PPVCON-2 group while comparable in both PPVOLV groups. In addition, interleukin-8 and myeloperoxidase levels tended to be higher in the PPVCON-4 group compared with the PPVOLV-4 group. CONCLUSIONS: In contrast to conventional ventilation, open lung ventilation preserves the response to delayed surfactant treatment in surfactant-deficient newborn piglets. This sustained response is accompanied by an attenuation of secondary lung injur

Shared decision-making and the duration of medical consultations: A systematic review and meta-analysis

Objective: 1) determine whether increased levels of Shared Decision-Making (SDM) affect consultation duration, 2) investigate the intervention characteristics involved. Methods: MEDLINE, EMBASE, CINAHL and Cochrane library were systematically searched for experimental and cross-sectional studies up to December 2021. A best-evidence synthesis was performed, and interventions characteristics that increased at least one SDM-outcome, were pooled and descriptively analyzed. Results: Sixty-three studies were selected: 28 randomized clinical trials, 8 quasi-experimental studies, and 27 cross-sectional studies. Overall, pooling of data was not possible due to substantial heterogeneity. No differences in consultation duration were found more often than increased or decreased durations. Consultation times (minutes:seconds) were significantly increased only among interventions that: 1) targeted clinicians only (Mean Difference [MD] 1:30, 95% Confidence Interval [CI] 0:24–2:37); 2) were performed in primary care (MD 2:05, 95%CI 0:11–3:59; 3) used a group format (MD 2:25, 95%CI 0:45–4:05); 4) were not theory-based (MD 4:01, 95%CI 0:38–7:23). Conclusion: Applying SDM does not necessarily require longer consultation durations. Theory-based, multilevel implementation approaches possibly lower the risk of increasing consultation durations. Practice implications: The commonly heard concern that time hinders SDM implementation can be contradicted, but implementation demands multifaceted approaches and space for training and adapting work processes