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result(s) for
"Stedman, Matthew J. M."
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The molecular basis of FimT-mediated DNA uptake during bacterial natural transformation
by
Braus, Sebastian A. G.
,
Holz, Stefanie
,
Stedman, Matthew J. M.
in
101/6
,
631/326/41/1969/1852
,
631/326/41/2536
2022
Naturally competent bacteria encode sophisticated protein machinery for the uptake and translocation of exogenous DNA into the cell. If this DNA is integrated into the bacterial genome, the bacterium is said to be naturally transformed. Most competent bacterial species utilise type IV pili for the initial DNA uptake step. These proteinaceous cell-surface structures are composed of thousands of pilus subunits (pilins), designated as major or minor according to their relative abundance in the pilus. Here, we show that the minor pilin FimT plays an important role in the natural transformation of
Legionella pneumophila
. We use NMR spectroscopy, in vitro DNA binding assays and in vivo transformation assays to understand the molecular basis of FimT’s role in this process. FimT binds to DNA via an electropositive patch, rich in arginines, several of which are well-conserved and located in a conformationally flexible C-terminal tail. FimT orthologues from other
Gammaproteobacteria
share the ability to bind to DNA. Our results suggest that FimT plays an important role in DNA uptake in a wide range of competent species.
Many bacteria can take up exogenous DNA, in a process that often requires surface appendages composed of thousands of protein subunits called pilins. Here, Braus et al. show that a minor pilin binds directly to DNA and is important for DNA uptake in the pathogen
Legionella pneumophila
.
Journal Article
Selective digestive tract decontamination in critically ill adults with acute brain injuries: a post hoc analysis of a randomized clinical trial
by
Chimunda, Timothy
,
Broadfield, Emma
,
Schoeler, Isabella
in
Adults
,
Antibiotics
,
Antifungal agents
2024
PurposeThe aim of this study was to determine whether selective decontamination of the digestive tract (SDD) reduces in-hospital mortality in mechanically ventilated critically ill adults admitted to the intensive care unit (ICU) with acute brain injuries or conditions.MethodsWe carried out a post hoc analysis from a crossover, cluster randomized clinical trial. ICUs were randomly assigned to adopt or not to adopt a SDD strategy for two alternating 12-month periods, separated by a 3-month inter-period gap. Patients in the SDD group (n = 2791; 968 admitted to the ICU with an acute brain injury) received a 6-hourly application of an oral paste and administration of a gastric suspension containing colistin, tobramycin, and nystatin for the duration of mechanical ventilation, plus a 4-day course of an intravenous antibiotic with a suitable antimicrobial spectrum. Patients in the control group (n = 3191; 1093 admitted to the ICU with an acute brain injury) received standard care. The primary outcome was in-hospital mortality within 90 days. There were four secondary clinical outcomes: death in ICU, ventilator-, ICU- and hospital-free days to day 90.ResultsOf 2061 patients with acute brain injuries (mean age, 55.8 years; 36.4% women), all completed the trial. In patients with acute brain injuries, there were 313/968 (32.3%) and 415/1093 (38%) in-hospital deaths in the SDD and standard care groups (unadjusted odds ratio [OR], 0.76, 95% confidence interval [CI] 0.63–0.92; p = 0.004). The use of SDD was associated with statistically significant improvements in the four clinical secondary outcomes compared to standard care. There was no significant heterogeneity of treatment effect between patients with and without acute brain injuries (interaction p = 0.22).ConclusionsIn this post hoc analysis of a randomized clinical trial in critically ill patients with acute brain injuries receiving mechanical ventilation, the use of SDD significantly reduced in-hospital mortality in patients compared to standard care without SDD. These findings require confirmation.
Journal Article
Epidemiological Investigation of a Mortality Event in a Translocated Gopher Tortoise (Gopherus polyphemus) Population in Northwest Florida
by
Norton, Terry M.
,
Stacy, Nicole I.
,
Aresco, Matthew J.
in
BASIC BIOLOGICAL SCIENCES
,
Cold weather
,
Contaminants
2020
Nokuse Plantation, a 22,055 ha private conservation preserve in northwest Florida, is a recipient site for gopher tortoises translocated from development sites in Florida. Since 2006, Nokuse has received over 5,000 tortoises from multiple development sites. During 2013-2015, 52 tortoises were found sick (
= 14) or dead (
= 38) in multiple soft-release enclosures in which tortoises consistently exhibited clinical signs, with additional sick (
= 5) and dead (
= 5) tortoises presenting similarly during 2016-2017. When found alive, tortoises behaved abnormally (e.g., frequently out of burrows during cold weather, pacing along enclosure fencing), appeared emaciated, were lethargic, and had developed redness under plastron scutes. Similar numbers of male (
= 28) and female (
= 32) tortoises were recovered along with two of unidentified sex, including mainly adults (
= 59) and three subadults. Physical examination, blood analysis, and other diagnostics were indicative of starvation and dehydration. Most sick tortoises provided with supportive care recovered. Necropsy findings generally confirmed starvation, with no evidence of infectious pathogens or contaminants. There were no apparent differences in quality of habitat, plant community, or soil or water among affected and unaffected enclosures. Botanical surveys indicated adequate forage quality and quantity, with no poisonous exotic or native plants detected. No land management practices changed prior to this event. Analysis of epidemiological data and demographic factors from before and during this mortality event identified initial density of tortoises in the enclosures as exerting the strongest influence on detection of tortoise morbidity and mortality. We believe that the stress associated with mixing tortoises from different populations and at higher densities during translocation impacted an individual tortoise's ability to obtain or absorb adequate nutrients from foraging, ultimately leading to a wasting condition consistent with starvation. Based on our findings, we recommend a maximum of 3 gopher tortoises per ha in soft-release enclosures for translocation, but further research is warranted to investigate the complexity of stress and social pressures associated with translocation.
Journal Article
DECRYPT trial: study protocol for a phase II randomised controlled trial of cognitive therapy for post-traumatic stress disorder (PTSD) in youth exposed to multiple traumatic stressors
2021
BackgroundPost-traumatic stress disorder (PTSD) is a distressing and disabling condition that affects significant numbers of children and adolescents. Youth exposed to multiple traumas (eg, abuse, domestic violence) are at particular risk of developing PTSD. Cognitive therapy for PTSD (CT-PTSD), derived from adult work, is a theoretically informed, disorder-specific form of trauma-focused cognitive–behavioural therapy. While efficacious for child and adolescent single-event trauma samples, its effectiveness in routine settings with more complex, multiple trauma-exposed youth has not been established. The Delivery of Cognitive Therapy for Young People after Trauma randomised controlled trial (RCT) examines the effectiveness of CT-PTSD for treating PTSD following multiple trauma exposure in children and young people in comparison with treatment as usual (TAU).Methods/designThis protocol describes a two-arm, patient-level, single blind, superiority RCT comparing CT-PTSD (n=60) with TAU (n=60) in children and young people aged 8–17 years with a diagnosis of PTSD following multiple trauma exposure. The primary outcome is PTSD severity assessed using the Children’s Revised Impact of Event Scale (8-item version) at post-treatment (ie, approximately 5 months post-randomisation). Secondary outcomes include structured interview assessment for PTSD, complex PTSD symptoms, depression and anxiety, overall functioning and parent-rated mental health. Mid-treatment and 11-month and 29-month post-randomisation assessments will also be completed. Process–outcome evaluation will consider which mechanisms underpin or moderate recovery. Qualitative interviews with the young people, their families and their therapists will be undertaken. Cost-effectiveness of CT-PTSD relative to TAU will be also be assessed.Ethics and disseminationThis trial protocol has been approved by a UK Health Research Authority Research Ethics Committee (East of England–Cambridge South, 16/EE/0233). Findings will be disseminated broadly via peer-reviewed empirical journal articles, conference presentations and clinical workshops.Trial registrationISRCTN12077707. Registered 24 October 2016 (http://www.isrctn.com/ISRCTN12077707). Trial recruitment commenced on 1 February 2017. It is anticipated that recruitment will continue until June 2021, with 11-month assessments being concluded in May 2022.
Journal Article
Limb-Girdle Muscular Dystrophy in the United States
2006
Limb-girdle muscular dystrophy (LGMD) has been linked to 15 chromosomal loci, 7 autosomal-dominant (LGMD1A to E) and 10 autosomal-recessive (LGMD2A to J). To determine the distribution of subtypes among patients in the United States, 6 medical centers evaluated patients with a referral diagnosis of LGMD. Muscle biopsies provided histopathology and immunodiagnostic testing, and their protein abnormalities along with clinical parameters directed mutation screening. The diagnosis in 23 patients was a disorder other than LGMD. Of the remaining 289 unrelated patients, 266 had muscle biopsies sufficient for complete microscopic evaluation; 121 also underwent Western blotting. From this combined evaluation, the distribution of immunophenotypes is 12% calpainopathy, 18% dysferlinopathy, 15% sarcoglycanopathy, 15% dystroglycanopathy, and 1.5% caveolinopathy. Genotypes distributed among 2 dominant and 7 recessive subtypes have been determined for 83 patients. This study of a large racially and ethnically diverse population of patients with LGMD indicates that establishing a putative subtype is possible more than half the time using available diagnostic testing. An efficient approach to genotypic diagnosis is muscle biopsy immunophenotyping followed by directed mutational analysis. The most common LGMDs in the United States are calpainopathies, dysferlinopathies, sarcoglycanopathies, and dystroglycanopathies.
Journal Article