The origins of specificity in the microcin-processing protease TldD/E

TldD and TldE proteins are involved in the biosynthesis of microcin B17 (MccB17), an Escherichia coli thiazole/oxazole-modified peptide toxin targeting DNA gyrase. Using a combination of biochemical and crystallographic methods we show that E. coli TldD and TldE interact to form a heterodimeric metalloprotease. TldD/E cleaves the N-terminal leader sequence from the modified MccB17 precursor peptide, to yield mature antibiotic, while it has no effect on the unmodified peptide. Both proteins are essential for the activity; however, only the TldD subunit forms a novel metal-containing active site within the hollow core of the heterodimer. Peptide substrates are bound in a sequence-independent manner through beta sheet interactions with TldD and are likely cleaved via a thermolysin-type mechanism. We suggest that TldD/E acts as a "molecularpencil sharpener'': unfoldedpoly-peptides are fed through a narrow channel into the active site and processively truncated through the cleavage of short peptides from the N-terminal end

Neurosyphilis Increases Human Immunodeficiency Virus (HIV)-associated Central Nervous System Inflammation but Does Not Explain Cognitive Impairment in HIV-infected Individuals With Syphilis.

Background: Individuals infected with human immunodeficiency virus (HIV) who have previously had syphilis may have cognitive impairment. We tested the hypothesis that neurosyphilis causes cognitive impairment in HIV by amplifying HIV-related central nervous system (CNS) inflammation. Methods: HIV-infected participants enrolled in a study of cerebrospinal fluid (CSF) abnormalities in syphilis underwent the mental alternation test (MAT), venipuncture, and lumbar puncture. CSF concentrations of chemokine (C-X-C motif) ligand 10 (CXCL10), chemokine (C-C motif) ligand 2 (CCL2), and neurofilament light (NFL) were determined by commercial assays. The proportion of peripheral blood mononuclear cells (PBMCs) and of CSF white blood cells (WBCs) that were activated monocytes (CD14+CD16+) was determined by flow cytometry. Neurosyphilis was defined as detection of Treponema pallidum 16S RNA in CSF or CSF white blood cells (WBCs) \u3e20/uL or a reactive CSF-Venereal Disease Research Laboratory (VDRL) test; uncomplicated syphilis was defined as undetectable CSF T. pallidum, CSF WBCs ≤5/uL and nonreactive CSF-VDRL. MATlow. Results: Median proportion of PBMCs that were activated monocytes (16.6 vs. 5.3), and median CSF CXCL10 (10658 vs. 2530 units), CCL2 (519 vs. 337 units) and HIV RNA (727 vs. 50 c/mL) were higher in neurosyphilis than in uncomplicated syphilis (P ≤ .001 for all comparisons). Neurosyphilis was not related to low MAT scores. Participants with low MAT scores had higher median CSF CXCL10 (10299 vs. 3650 units, P = .008) and CCL2 (519 vs. 365 units, P = .04) concentrations than those with high MAT scores. Conclusions: Neurosyphilis may augment HIV-associated CNS inflammation, but it does not explain cognitive impairment in HIV-infected individuals with syphilis

Preparing midwifery students for traumatic workplace events: Findings from the POPPY (programme for the prevention of posttraumatic stress disorder in midwifery) feasibility study

Midwifery students can experience events on clinical placements that they perceive to be traumatic. There is currently no requirement to provide training about the nature of trauma, normal responses, or the most helpful ways of self-managing these. The POPPY programme, developed for qualified midwives, incorporates educational (the POPPY workshop) and supportive resources to prevent the development of Post-Traumatic Stress Disorder in midwives. As part of the feasibility evaluation of POPPY, the POPPY workshop element was adapted for pre-registration midwifery students (PreR-POPPY). Attention to this issue during pre-registration education could improve student experience and support student retention. To identify students' perspectives on the contents (clarity, understandability, organisation of the workshop, utility, relevance), their understanding of trauma and psychological responses, and confidence in recognising and managing early signs of distress following participation in a PreR-POPPY workshop. Perspectives on preferred timing in their midwifery programmes, and methods of delivery were also sought. In keeping with educational evaluations, anonymous feedback was collected from students. Two higher education institutes. Midwifery undergraduate students on the three year or shortened programme for registered nurses (n = 131), and midwifery educators (n = 5). Students participated in the workshop and provided feedback immediately. Midwifery educators participated in a meeting with the researchers to provide feedback. High levels of satisfaction with the contents of the workshop were identified. Ninety-nine percent of students would recommend the workshop to other midwifery students. Provision of the workshop early in midwifery programmes, revisited at later points, was strongly endorsed. Learning outcomes were very positive for understanding trauma/early stress responses, and recognising and managing early responses to trauma. Strong endorsement for the provision of the workshop was received from the midwifery educators. The pre-registration adapted POPPY workshop should be routinely provided in preregistration midwifery. [Abstract copyright: Copyright © 2018. Published by Elsevier Ltd.

Intimate physical contact between people from different households during the COVID-19 pandemic: a mixed-methods study from a large, quasi-representative survey (Natsal-COVID)

OBJECTIVES: Physical distancing as a non-pharmaceutical intervention aims to reduce interactions between people to prevent SARS-CoV-2 transmission. Intimate physical contact outside the household (IPCOH) may expand transmission networks by connecting households. We aimed to explore whether intimacy needs impacted adherence to physical distancing following lockdown in Britain in March 2020. METHODS: The Natsal-COVID web-panel survey (July-August 2020) used quota-sampling and weighting to achieve a quasi-representative population sample. We estimate reporting of IPCOH with a romantic/sexual partner in the 4 weeks prior to interview, describe the type of contact, identify demographic and behavioural factors associated with IPCOH and present age-adjusted ORs (aORs). Qualitative interviews (n=18) were conducted to understand the context, reasons and decision making around IPCOH. RESULTS: Of 6654 participants aged 18-59 years, 9.9% (95% CI 9.1% to 10.6%) reported IPCOH. IPCOH was highest in those aged 18-24 (17.7%), identifying as gay or lesbian (19.5%), and in steady non-cohabiting relationships (56.3%). IPCOH was associated with reporting risk behaviours (eg, condomless sex, higher alcohol consumption). IPCOH was less likely among those reporting bad/very bad health (aOR 0.54; 95% CI 0.32 to 0.93) but more likely among those with COVID-19 symptoms and/or diagnosis (aOR 1.34; 95% CI 1.10 to 1.65). Two-thirds (64.4%) of IPCOH was reported as being within a support bubble. Qualitative interviews found that people reporting IPCOH deliberated over, and made efforts to mitigate, the risks. CONCLUSIONS: Given 90% of people did not report IPCOH, this contact may not be a large additional contributor to SARS-CoV-2 transmission, although heterogeneity exists within the population. Public health messages need to recognise how single people and partners living apart balance sexual intimacy and relationship needs with adherence to control measures

Structural and mechanistic analysis of ATPase inhibitors targeting mycobacterial DNA gyrase

Objectives To evaluate the efficacy of two novel compounds against mycobacteria and determine the molecular basis of their action on DNA gyrase using structural and mechanistic approaches. Methods Redx03863 and Redx04739 were tested in antibacterial assays, and also against their target, DNA gyrase, using DNA supercoiling and ATPase assays. X-ray crystallography was used to determine the structure of the gyrase B protein ATPase sub-domain from Mycobacterium smegmatis complexed with the aminocoumarin drug novobiocin, and structures of the same domain from Mycobacterium thermoresistibile complexed with novobiocin, and also with Redx03863. Results Both compounds, Redx03863 and Redx04739, were active against selected Gram-positive and Gram-negative species, with Redx03863 being the more potent, and Redx04739 showing selectivity against M. smegmatis. Both compounds were potent inhibitors of the supercoiling and ATPase reactions of DNA gyrase, but did not appreciably affect the ATP-independent relaxation reaction. The structure of Redx03863 bound to the gyrase B protein ATPase sub-domain from M. thermoresistibile shows that it binds at a site adjacent to the ATP- and novobiocin-binding sites. We found that most of the mutations that we made in the Redx03863-binding pocket, based on the structure, rendered gyrase inactive. Conclusions Redx03863 and Redx04739 inhibit gyrase by preventing the binding of ATP. The fact that the Redx03863-binding pocket is distinct from that of novobiocin, coupled with the lack of activity of resistant mutants, suggests that such compounds could have potential to be further exploited as antibiotics

Utility of Phase Angle to Identify Cachexia and Assess Mortality in End-Stage Renal Disease

© 2020 American Society for Nutrition. Published by Elsevier Inc. This is an Open access article under the CC-BY-NC-ND license. https://creativecommons.org/licenses/by-nc-nd/4.0/Objectives This cross-sectional analysis sought to identify cachexia and assess survival using phase angle (PA) in patients with end-stage renal disease (ESRD) receiving haemodialysis. Methods Patients receiving haemodialysis (n = 87, mean age 65.9 +/– 13.0) completed a Phase Angle (PA; 50 khz) measurement using bioelectrical impedance analysis. Cachexia variables were recorded according to Evans et al. definition (2008) including nutritional and functional measures (weight, Body Mass Index (BMI), Hand Grip Strength (HGS), Lean Tissue Mass (LTM), C-Reative Protein (CRP), serum albumin, haemoglobin, appetite (Functional Assessment of Anorexia/Cachexia Treatment (FAACT)) and fatigue (Functional Assessment of Chronic Illness Therapy (FACIT)). Survival was assessed at 12 months. Mann Whitney-U and Spearman correlation coefficient were conducted. Results The majority of patients completed follow up (n = 76). Eleven patients had died. Mean PA was not statistically different between those identified as cachectic and non-cachectic according to Evans et al. (2008) definition or between those patients that survived and died. However, patients that survived had better mean scores of weight, BMI, HGS, CRP, serum albumin and fatigue (FACIT). In addition, LTM scores were significantly better in patients that survived (P < .01). Appetite scores were also significantly better in patients that survived (P < .01) and those without cachexia (P = .01). Conclusions This study was part of a larger effort to clarity a phenotype of cachexia in ESRD. Unlike previous research, this study did not find PA useful in identifying patients at a higher risk of cachexia or death. However overall these patients had a very low mean PA. FAACT did discriminate between groups indicating self-reporting measurement tools of nutritional status were useful in identifying patients at a higher risk of cachexia and death. A larger sample and longer follow up is required to balance the limitations of this small study. Timing the administration of PA also requires consideration in future studies. Funding Sources Public Health Agency; Northern Ireland Kidney Research Fund.Peer reviewe

Interpreting cerebrospinal fluid pleocytosis in HIV in the era of potent antiretroviral therapy

Background: Cerebrospinal fluid (CSF) pleocytosis may be seen in asymptomatic HIV-infected individuals. This finding complicates interpretation of CSF abnormalities when such individuals are evaluated for other central nervous system infections. The goal of this study was to determine the relationship between CSF pleocytosis, central nervous system (CNS) antiretroviral penetration, adherence to antiretroviral medication regimens, neurological symptoms and performance on neuropsychological tests. Methods: Clinically stable HIV-infected individuals at any peripheral blood CD4+ T cell count or any plasma viral load were asked to attend study visits at entry and every 6 months thereafter for at least one year. At each visit, they underwent a standardized neurological and medication history; neurological examination; a brief neuropsychological test battery: venipuncture; lumbar puncture; and assessment of medication adherence. Generalized estimating equations (GEE) were used to assess the relationships between CSF pleocytosis and other variables. Results: CSF pleocytosis was independently and significantly related to lack of current antiretroviral use (OR 5.9, 95% CI 1.8-18.6, p = 0.003), CD4 count >200/ul (OR 23.4, 95% CI 3.1-177.3, p = 0.002) and detectable plasma HIV RNA (OR 3.3, 95% CI 1.1-9.4, p = 0.03). At visits where antiretrovirals were used, and taking into account detectable plasma HIV RNA, an antiretroviral regimen that contained two or more agents with good CNS penetration conferred a trend toward lower odds of CSF pleocytosis (OR 0.45, 95% CI 0.18-1.12, p = 0.087). Conclusion: CSF pleocytosis is a characteristic of HIV disease that varies significantly with easily identifiable clinical and laboratory features. Use of antiretroviral agents decreases the odds of pleocytosis. This association may be stronger when the regimen contains two or more agents with good CNS penetration.This work was supported by National Institutes of Health grant U54 NS 39406 (AI and CMM)

Using a generic definition of cachexia in patients with kidney disease receiving haemodialysis: a longitudinal (pilot) study

International audienceBACKGROUND: Research indicates that cachexia is common among persons with chronic illnesses and is associated with increased morbidity and mortality. However, there continues to be an absence of a uniformed disease-specific definition for cachexia in chronic kidney disease (CKD) patient populations. OBJECTIVE: The primary objective was to identify cachexia in patients receiving haemodialysis (HD) using a generic definition and then follow up on these patients for 12 months. METHOD: This was a longitudinal study of adult chronic HD patients attending two hospital HD units in the UK. Multiple measures relevant to cachexia, including body mass index (BMI), muscle mass [mid-upper arm muscle circumference (MUAMC)], handgrip strength (HGS), fatigue [Functional Assessment of Chronic Illness Therapy (FACIT)], appetite [Functional Assessment of Anorexia/Cachexia Therapy (FAACT)] and biomarkers [C-reactive protein (CRP), serum albumin, haemoglobin and erythropoietin resistance index (ERI)] were recorded. Baseline analysis included group differences analysed using an independent t-test, dichotomized values using the χ2 test and prevalence were reported using the Statistical Package for the Social Sciences 24 (IBM, Armonk, NY, USA). Longitudinal analysis was conducted using repeated measures analysis. RESULTS: A total of 106 patients (30 females and 76 males) were recruited with a mean age of 67.2 years [standard deviation (SD) 13.18] and dialysis vintage of 4.92 years (SD 6.12). At baseline, 17 patients were identified as cachectic, having had reported weight loss (e.g. \textgreater5% for \textgreater6 months) or BMI \textless20 kg/m2 and three or more clinical characteristics of cachexia. Seventy patients were available for analysis at 12 months (11 cachectic versus 59 not cachectic). The FAACT and urea reduction ratio statistically distinguished cachectic patients (P = 0.001). However, measures of weight, BMI, MUAMC, HGS, CRP, ERI and FACIT tended to worsen in cachectic patients. CONCLUSION: Globally, cachexia is a severe but frequently underrecognized problem. This is the first study to apply the defined characteristics of cachexia to a representative sample of patients receiving HD. Further, more extensive studies are required to establish a phenotype of cachexia in advanced CKD