Heme utilization in Vibrio cholerae and analysis of domains involved in the specificity of TonB for TonB-dependent receptors

textVibrio cholerae has multiple iron transport systems, one of which involves heme uptake through the outer membrane receptor HutA. This study demonstrates that V. cholerae encodes two additional TonB-dependent heme receptors, HutR and HasR. HutR has significant homology to HutA and to other bacterial outer membrane heme receptors, and the role of HutR in hemin utilization and its localization in the outer membrane were confirmed. The hutR gene was co-transcribed with the upstream gene ptrB, and expression from the ptrB promoter was negatively regulated by iron. HasR is most similar to the hemophore-utilizing heme receptors from Pseudomonas aeruginosa and Serratia marcescens. A mutant defective in all three heme receptors was unable to utilize hemin as an iron source. HutA and HutR functioned with either V. cholerae TonB1 or TonB2. In contrast, hemin uptake through HasR was TonB2- dependent. Efficient utilization of hemoglobin as an iron source required HutA and TonB1. The triple heme receptor mutant exhibited no defect in its ability to compete with its Vib- parental strain in an infant mouse model of infection, indicating that additional iron sources are present in vivo. V. cholerae utilized heme derived from marine invertebrate hemoglobins, suggesting that heme may be available to V. cholerae growing in the marine environment. Although E. coli TonB and V. cholerae TonB1 exhibit different specificities for outer membrane receptors, these TonB proteins are similar enough that functional chimeras can be created between them. The activities of the chimeric TonB proteins demonstrated that the C-terminal one-third of TonB constitutes a functional domain responsible for receptor specificity. A Pro238Thr substitution in V. cholerae TonB1 resulted in the ability of TonB1 to recognize a wider range of receptors, indicating that very C-terminal end of TonB1 determines receptor specificity. Domain-switching experiments between E. coli ChuA and V. cholerae HutA showed that the TonB box heptapeptide at the Nterminus of these receptors does not contain specificity determinants. Instead, specificity was controlled by the residue immediately preceding the TonB box. Taken together, these data suggest that functional interactions take place between the C-terminus of TonB and the very N-terminal domain of TonB-dependent receptors.Biological Sciences, School o

Aetiology of acute meningoencephalitis in Cambodian children, 2010–2013

Acute meningoencephalitis (AME) is associated with considerable morbidity and mortality in children in developing countries. Clinical specimens were collected from children presenting with AME at two Cambodian paediatric hospitals to determine the major aetiologies associated with AME in the country. Cerebrospinal fluid (CSF) and blood samples were screened by molecular and cell culture methods for a range of pathogens previously associated with AME in the region. CSF and serum (acute and convalescent) were screened for antibodies to arboviruses such as Japanese encephalitis virus (JEV), dengue virus (DENV), and chikungunya virus (CHIKV). From July 2010 through December 2013, 1160 children (one month to 15 years of age) presenting with AME to two major paediatric hospitals were enroled into the study. Pathogens associated with AME were identified using molecular diagnostics, cell culture and serology. According to a diagnostic algorithm, a confirmed or highly probable aetiologic agent was detected in 35.0% (n=406) of AME cases, with a further 9.2% (total: 44.2%, n=513) aetiologies defined as suspected. JEV (24.4%, n=283) was the most commonly identified pathogen followed by Orientia tsutsugamushi (4.7%, n=55), DENV (4.6%, n=53), enteroviruses (3.5%, n=41), CHIKV (2.0%, n=23) and Streptococcus pneumoniae (1.6%, n=19). The majority of aetiologies identified for paediatric AME in Cambodia were vaccine preventable and/or treatable with appropriate antimicrobials

Impact of opioid-free analgesia on pain severity and patient satisfaction after discharge from surgery: multispecialty, prospective cohort study in 25 countries

Background: Balancing opioid stewardship and the need for adequate analgesia following discharge after surgery is challenging. This study aimed to compare the outcomes for patients discharged with opioid versus opioid-free analgesia after common surgical procedures.Methods: This international, multicentre, prospective cohort study collected data from patients undergoing common acute and elective general surgical, urological, gynaecological, and orthopaedic procedures. The primary outcomes were patient-reported time in severe pain measured on a numerical analogue scale from 0 to 100% and patient-reported satisfaction with pain relief during the first week following discharge. Data were collected by in-hospital chart review and patient telephone interview 1 week after discharge.Results: The study recruited 4273 patients from 144 centres in 25 countries; 1311 patients (30.7%) were prescribed opioid analgesia at discharge. Patients reported being in severe pain for 10 (i.q.r. 1-30)% of the first week after discharge and rated satisfaction with analgesia as 90 (i.q.r. 80-100) of 100. After adjustment for confounders, opioid analgesia on discharge was independently associated with increased pain severity (risk ratio 1.52, 95% c.i. 1.31 to 1.76; P < 0.001) and re-presentation to healthcare providers owing to side-effects of medication (OR 2.38, 95% c.i. 1.36 to 4.17; P = 0.004), but not with satisfaction with analgesia (beta coefficient 0.92, 95% c.i. -1.52 to 3.36; P = 0.468) compared with opioid-free analgesia. Although opioid prescribing varied greatly between high-income and low- and middle-income countries, patient-reported outcomes did not.Conclusion: Opioid analgesia prescription on surgical discharge is associated with a higher risk of re-presentation owing to side-effects of medication and increased patient-reported pain, but not with changes in patient-reported satisfaction. Opioid-free discharge analgesia should be adopted routinely

Analysis of Residues Determining Specificity of Vibrio cholerae TonB1 for Its Receptors

In gram-negative organisms, high-affinity transport of iron substrates requires energy transduction to specific outer membrane receptors by the TonB-ExbB-ExbD complex. Vibrio cholerae encodes two TonB proteins, one of which, TonB1, recognizes only a subset of V. cholerae TonB-dependent receptors and does not facilitate transport through Escherichia coli receptors. To investigate the receptor specificity exhibited by V. cholerae TonB1, chimeras were created between V. cholerae TonB1 and E. coli TonB. The activities of the chimeric TonB proteins in iron utilization assays demonstrated that the C-terminal one-third of either TonB confers the receptor specificities associated with the full-length TonB. Single-amino-acid substitutions near the C terminus of V. cholerae TonB1 were identified that allowed TonB1 to recognize E. coli receptors and at least one V. cholerae TonB2-dependent receptor. This indicates that the very C-terminal end of V. cholerae TonB1 determines receptor specificity. The regions of the TonB-dependent receptors involved in specificity for a particular TonB protein were investigated in experiments involving domain switching between V. cholerae and E. coli receptors exhibiting different TonB specificities. Switching the conserved TonB box heptapeptides at the N termini of these receptors did not alter their TonB specificities. However, replacing the amino acid immediately preceding the TonB box in E. coli receptors with an aromatic residue allowed these receptors to use V. cholerae TonB1. Further, site-directed mutagenesis of the TonB box −1 residue in a V. cholerae TonB2-dependent receptor demonstrated that a large hydrophobic amino acid in this position promotes recognition of V. cholerae TonB1. These data suggest that the TonB box −1 position controls productive interactions with V. cholerae TonB1

The humeral origin of the brachioradialis muscle: An unusual site of high radial nerve compression

Radial nerve compression is seldom encountered in the upper arm, and most commonly described compression syndromes have their anatomical cause in the forearm. The teres major, the triceps muscle, the intermuscular septum region and the space between the brachialis and brachioradialis muscles have all been identified as radial nerve compression sites above the elbow. We describe the case of a 38-year-old male patient who presented with dorso-lateral forearm pain and paraesthesias without neurological deficit. Surgical exploration revealed radial nerve compression at the humeral origin of the brachioradialis muscle. Liberation of the nerve at this site was successful at relieving the symptoms. To our knowledge, this compression site has not been described in the literature. © 2013 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Breastfeeding after vertical reduction mammaplasty using a superior pedicle

Between January 1996 and December 2002, 189 women underwent bilateral superior-pedicle breast reduction according to the Lejour technique, at Brugmann University Hospital (Brussels, Belgium). We conducted a retrospective study on the 18 women who gave birth since the operation. Our aim was to find out how many of them breastfed, the reasons for not breastfeeding from those who did not, and to look for parameters that might have interfered with breastfeeding success. The latter was defined as the ability to breastfeed for a minimum of 2 weeks, with or without nutritional supplementation. Eight patients out of 18 successfully breastfed for an average duration of 1.9 ± 1.3 months, and ceased to do so in most cases for reasons other than spontaneous cessation of lactation. Another eight women made no attempt at breastfeeding for various reasons. According to data obtained from a report of the Belgian French-speaking Community, our series of patients made proportionally fewer breastfeeding attempts than women from a culturally similar context (74%). However, they exclusively breastfed for a median duration of 3 months, superior to the 8-9 weeks of the women included in the government report. Two patients failed at their breastfeeding attempts. We were able to demonstrate the role of neither anthropomorphic, operation-related, neuro-sensitive nor psychological factors in those failures. Our results, when confronted to those of similar studies, show that the Lejour technique allows breastfeeding in proportions similar to those of any other pedicled technique. © 2006 British Association of Plastic, Reconstructive and Aesthetic Surgeons.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

The humeral origin of the brachioradialis muscle: An unusual site of high radial nerve compression

Radial nerve compression is seldom encountered in the upper arm, and most commonly described compression syndromes have their anatomical cause in the forearm. The teres major, the triceps muscle, the intermuscular septum region and the space between the brachialis and brachioradialis muscles have all been identified as radial nerve compression sites above the elbow. We describe the case of a 38-year-old male patient who presented with dorso-lateral forearm pain and paraesthesias without neurological deficit. Surgical exploration revealed radial nerve compression at the humeral origin of the brachioradialis muscle. Liberation of the nerve at this site was successful at relieving the symptoms. To our knowledge, this compression site has not been described in the literature. © 2013 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.SCOPUS: ar.jinfo:eu-repo/semantics/publishe