Sterically hindered Lewis acid and base centers are unable to form Lewis adducts, instead forming frustrated Lewis pairs (FLPs), where latent reactivity can be utilized for the activation of small ...molecules. Applying FLP chemistry into polymeric frameworks transforms this chemistry into responsive and functional materials. Here, we report a versatile synthesis strategy for the preparation of macromolecular FLPs and explore its potential with the ring-opening reactions of cyclic ethers. Addition of the cyclic substrates triggered polymer network formation, where the extent of cross-linking, strength of network, and reactivity are tuned by the steric and electronic properties of the ethers. The resultant networks behave like covalently cross-linked polymers, demonstrating the versatility of FLPs to simultaneously tune both small-molecule capture and mechanical properties of materials.
Frustrated Lewis pairs (FLPs) are now ubiquitous as metal-free catalysts in an array of different chemical transformations. In this paper we show that this reactivity can be transferred to a ...polymeric system, offering advantageous opportunities at the interface between catalysis and stimuli-responsive materials. Formation of cyclic carbonates from cyclic ethers using CO2 as a C1 feedstock continues to be dominated by metal-based systems. When paired with a suitable nucleophile, discrete aryl or alkyl boranes have shown significant promise as metal-free Lewis acidic alternatives, although catalyst reuse remains illusive. Herein, we leverage the reactivity of FLPs in a polymeric system to promote CO2/cyclic ether coupling catalysis that can be tuned for the desired epoxide or oxetane substrate. Moreover, these macromolecular FLPs can be reused across multiple reaction cycles, further increasing their appeal over analogous small molecule systems.
The ecology of infectious disease in wildlife has become a pivotal theme in animal and public health. Studies of infectious disease ecology rely on robust surveillance of pathogens in reservoir ...hosts, often based on serology, which is the detection of specific antibodies in the blood and is used to infer infection history. However, serological data can be inaccurate for inference to infection history for a variety of reasons. Two major aspects in any serological test can substantially impact results and interpretation of antibody prevalence data: cross-reactivity and cut-off thresholds used to discriminate positive and negative reactions. Given the ubiquitous use of serology as a tool for surveillance and epidemiological modeling of wildlife diseases, it is imperative to consider the strengths and limitations of serological test methodologies and interpretation of results, particularly when using data that may affect management and policy for the prevention and control of infectious diseases in wildlife. Greater consideration of population age structure and cohort representation, serological test suitability and standardized sample collection protocols can ensure that reliable data are obtained for downstream modeling applications to characterize, and evaluate interventions for, wildlife disease systems.
Tuberculosis (TB) transmission and prevalence are dynamic over time, and heterogeneous within populations. Public health programmes therefore require up-to-date, accurate epidemiological data to ...appropriately allocate resources, target interventions, and track progress towards End TB goals. Current methods of TB surveillance often rely on case notifications, which are biased by access to healthcare, and TB disease prevalence surveys, which are highly resource-intensive, requiring many tens of thousands of people to be tested to identify high-risk groups or capture trends. Surveys of "latent TB infection", or immunoreactivity to Mycobacterium tuberculosis (Mtb), using tests such as interferon-gamma release assays (IGRAs) could provide a way to identify TB transmission hotspots, supplementing information from disease notifications, and with greater spatial and temporal resolution than is possible to achieve in disease prevalence surveys. This cross-sectional survey will investigate the prevalence of Mtb immunoreactivity amongst young children, adolescents and adults in Blantyre, Malawi, a high HIV-prevalence city in southern Africa. Through this study we will estimate the annual risk of TB infection (ARTI) in Blantyre and explore individual- and area-level risk factors for infection, as well as investigating geospatial heterogeneity of Mtb infection (and its determinants), and comparing these to the distribution of TB disease case-notifications. We will also evaluate novel diagnostics for Mtb infection (QIAreach QFT) and sampling methodologies (convenience sampling in healthcare settings and community sampling based on satellite imagery), which may increase the feasibility of measuring Mtb infection at large scale. The overall aim is to provide high-resolution epidemiological data and provide new insights into methodologies which may be used by TB programmes globally.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Local information is needed to guide targeted interventions for respiratory infections such as tuberculosis (TB). Case notification rates (CNRs) are readily available, but systematically ...underestimate true disease burden in neighbourhoods with high diagnostic access barriers. We explored a novel approach, adjusting CNRs for under-notification (P:N ratio) using neighbourhood-level predictors of TB prevalence-to-notification ratios. We analysed data from 1) a citywide routine TB surveillance system including geolocation, confirmatory mycobacteriology, and clinical and demographic characteristics of all registering TB patients in Blantyre, Malawi during 2015-19, and 2) an adult TB prevalence survey done in 2019. In the prevalence survey, consenting adults from randomly selected households in 72 neighbourhoods had symptom-plus-chest X-ray screening, confirmed with sputum smear microscopy, Xpert MTB/Rif and culture. Bayesian multilevel models were used to estimate adjusted neighbourhood prevalence-to-notification ratios, based on summarised posterior draws from fitted adult bacteriologically-confirmed TB CNRs and prevalence. From 2015-19, adult bacteriologically-confirmed CNRs were 131 (479/371,834), 134 (539/415,226), 114 (519/463,707), 56 (283/517,860) and 46 (258/578,377) per 100,000 adults per annum, and 2019 bacteriologically-confirmed prevalence was 215 (29/13,490) per 100,000 adults. Lower educational achievement by household head and neighbourhood distance to TB clinic was negatively associated with CNRs. The mean neighbourhood P:N ratio was 4.49 (95% credible interval CrI: 0.98-11.91), consistent with underdiagnosis of TB, and was most pronounced in informal peri-urban neighbourhoods. Here we have demonstrated a method for the identification of neighbourhoods with high levels of under-diagnosis of TB without the requirement for a prevalence survey; this is important since prevalence surveys are expensive and logistically challenging. If confirmed, this approach may support more efficient and effective targeting of intensified TB and HIV case-finding interventions aiming to accelerate elimination of urban TB.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Ratios of bacteriologically positive tuberculosis (TB) prevalence to notification rates are used to characterise typical durations of TB disease. However, this ignores the clinical spectrum of ...tuberculosis disease and potentially long infectious periods with minimal or no symptoms prior to care-seeking.
We developed novel statistical models to estimate progression from initial bacteriological positivity including smear conversion, symptom onset and initial care-seeking. Case-detection ratios, TB incidence, durations, and other parameters were estimated by fitting the model to tuberculosis prevalence survey and notification data (one subnational and 11 national datasets) within a Bayesian framework using Markov chain Monte Carlo methods.
Analysis across 11 national datasets found asymptomatic tuberculosis durations in the range 4-8 months for African countries; three countries in Asia (Cambodia, Lao PDR, and Philippines) showed longer durations of > 1 year. For the six countries with relevant data, care-seeking typically began half-way between symptom onset and notification. For Kenya and Blantyre, Malawi, individual-level data were available. The sex-specific durations of asymptomatic bacteriologically-positive tuberculosis were 9.0 months (95% credible interval CrI: 7.2-11.2) for men and 8.1 months (95% CrI: 6.2-10.3) for women in Kenya, and 4.9 months (95% CrI: 2.6-7.9) for men and 3.5 months (95% CrI: 1.3-6.2) for women in Blantyre. Age-stratified analysis of data for Kenya showed no strong age-dependence in durations. For Blantyre, HIV-stratified analysis estimated an asymptomatic duration of 1.3 months (95% CrI: 0.3-3.0) for HIV-positive people, shorter than the 8.5 months (95% CrI: 5.0-12.7) for HIV-negative people. Additionally, case-detection ratios were higher for people living with HIV than HIV-negative people (93% vs 71%).
Asymptomatic TB disease typically lasts around 6 months. We found no evidence of age-dependence, but much shorter durations among people living with HIV, and longer durations in some Asian settings. To eradicate TB transmission, greater gains may be achieved by proactively screening people without symptoms through active case finding interventions.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The versatile chemistry of boronic acid and boronate ester containing polymers has led to key applications in drug delivery, chemical sensing, and dynamic materials. However, their use in polymeric ...Frustrated Lewis pairs (FLP) remains unreported. In this paper we report the synthesis of a novel fluorinated borinate ester copolymer which, when combined with a suitable Lewis basic copolymer, generates polymeric FLP networks capable of responsive gelation. The borinate ester moiety, bis(pentafluorophenyl)borinic acid tetrafluorophenyl ester, was affixed to a polystyrene copolymer by a two-step post-polymerisation modification, which can be easily upscaled and purified. The Gutmann-Beckett method suggests these fluorinated borinate ester moieties are amongst the most Lewis acidic boron-containing polymers reported to date. Upon mixing with a Lewis basic copolymer poly(styrene-co-p-diphenylphosphino styrene), gelation cannot be achieved due to steric hindrance around the Lewis centres. However, network formation can be triggered by addition of small molecules such as diethylazodicarboxylate (DEAD) and cyclic ethers. The physical parameters and nature of the crosslinks of the gels prepared from different crosslinkers were probed by rheology. All networks demonstrated strong elastic behaviour, corresponding to covalently crosslinked materials. DEAD crosslinked gels displayed different behaviour to those triggered by cyclic ethers, indicating that mechanism of small molecule activation also plays an important role in the mechanical properties of poly(FLP) gels.
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•Synthesis of novel borinate ester copolymer as a polymeric Lewis acid.•Polymeric Frustrated Lewis pairs of borinate esters and phosphines form responsive gels.•Tunable crosslinks with cyclic ethers and azos alter rheology and reactivity.
to determine the prevalence of extended-spectrum β-lactamases (ESBLs) in Escherichia coli from poultry in Great Britain (GB).
E. coli was isolated from 388 broiler chicken caecal samples from 22 ...abattoirs and from boot swabs from 442 turkey flocks over successive 1 year periods. CHROMagar ECC with and without cephalosporin antibiotics was used as isolation medium and the chicken study also used CHROMagar CTX. ESBL phenotype isolates were tested for the presence of bla(CTX-M,) bla(OXA), bla(SHV), bla(TEM) and ampC genes(.) CTX-M isolates were tested for O25 serogroup, replicon, CTX-M sequence, multilocus sequence type (MLST), PFGE type, plasmid transfer and qnrA, qnrB, qnrS, qepA and aac(6')-Ib genes.
CTX-M-carrying E. coli were isolated from 54.5% of the broiler abattoirs and from 3.6% of individual broiler caecal samples and were CTX-M sequence types 1 (mainly), 3 and 15 with replicon types I1-γ, A/C and P/F, and I1-γ, respectively. CTX-M-carrying E. coli were isolated from 5.2% of turkey meat production farms and 6.9% of turkey breeder farms and were CTX-M sequence types 1, 14 (mainly), 15 and 55 with mainly replicon types F, FIA, K and I1-γ, respectively. None of the CTX-M isolates was serogroup O25. PFGE/MLST showed the CTX-M isolates to be clonally diverse, although MLST 156 with CTX-M-15 was isolated from both chickens and turkeys and has been previously reported in gulls. CTX-M-negative, ESBL- and bla(TEM)-positive strains were mainly TEM-52C.
poultry-derived CTX-M E. coli in GB are different from major CTX-M sequence types causing disease in humans.
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