Nanoprecipitation of polymeric nanoparticle micelles based on 2-methacryloyloxyethyl phosphorylcholine (MPC) with 2-(diisopropylamino)ethyl methacrylate (DPA), for intracellular delivery applications

Biodistribution of nanoparticle-based intracellular delivery systems is mediated primarily by particle size and physicochemical properties. As such, overcoming the rapid removal of these by the reticuloendothelial system remains a significant challenge. To date, a number of copolymer nanoparticle systems based on 2-methacryloyloxyethyl phosphorylcholine (MPC) with 2-(diisopropylamino)ethyl methacrylate (DPA), displaying biomimetic and pH responsive properties, have been published, however these have been predominately polymersome based, whilst micelle systems have remained relatively unexplored. This study utilised nanoprecipitation to investigate the effects of solvent and buffer choice upon micelle size and polydispersity, and found using methanol produced monodisperse micelles of circa 70 nm diameter, whilst ethanol produced polydisperse systems with nanoparticles of circa 128 nm diameter. The choice of aqueous buffer, dialysis of the systems, extended storage, and exposure to a wide temperature range (5–70 °C) had no significant effect on micelle size, and the systems were highly resistant to dilution, indicating excellent colloidal stability. Optimisation of the nanoprecipitation process, post precipitation, was investigated, and model drugs successfully loaded whilst maintaining system stability. Subsequent in vitro studies suggested that the micelles were of negligible cellular toxicity, and an apparent cellular uptake was observed via confocal laser scanning microscopy. This paper presents the first report of an optimised nanoprecipitation methodology for the formation of MPC–DPA nanoparticle micelles, and in doing so achieved monodisperse systems with the size and physicochemical characteristics seen as desirable for long circulating therapeutic delivery vehicles

In situ Rb-Sr dating by collision cell, multicollection inductively-coupled plasma mass-spectrometry with pre-cell mass-filter, (CC-MC-ICPMS/MS)

We document the utility for in situ Rb–Sr dating of a one-of-a-kind tribrid mass spectrometer, ‘Proteus’, coupled to a UV laser ablation system. Proteus combines quadrupole mass-filter, collision cell and sector magnet with a multicollection inductively-coupled plasma mass spectrometer (CC-MC-ICPMS/MS). Compared to commercial, single collector, tribrid inductively-coupled plasma mass spectrometers (CC-ICPMS/MS) Proteus has enhanced ion transmission and offers simultaneous collection of all Sr isotopes using an array of Faraday cups. These features yield improved precision in measured (87)Sr/(86)Sr ratios, for a given mass of Sr analysed, approximately a factor of 25 in comparison to the Thermo Scientific™ iCAP TQ™ operated under similar conditions. Using SF(6) as a reaction gas on Proteus, measurements of Rb-doped NIST SRM (standard reference material) 987 solutions, with Rb/Sr ratios from 0.01–100, yield (87)Sr/(86)Sr that are indistinguishable from un-doped NIST SRM 987, demonstrating quantitative ‘chemical resolution’ of Rb from Sr. We highlight the importance of mass-filtering before the collision cell for laser ablation (87)Sr/(86)Sr analysis, using an in-house feldspar standard and a range of glass reference materials. By transmitting only those ions with mass-to-charge ratios 82–92 u/e into the collision cell, we achieve accurate (87)Sr/(86)Sr measurements without any corrections for atomic or polyatomic isobaric interferences. Without the pre-cell mass-filtering, measured in situ(87)Sr/(86)Sr ratios are inaccurate. Combining in situ measurements of Rb/Sr and radiogenic Sr isotope ratios we obtain mineral isochrons. We utilise a sample from the well-dated Dartmoor granite (285 ± 1 Ma) as a calibrant for our in situ ages and, using the same conditions, produce accurate Rb–Sr isochron ages for samples of the Fish Canyon tuff (28 ± 2 Ma) and Shap granite pluton (397 ± 1 Ma). Analysing the same Dartmoor granite sample using identical laser conditions and number of spot analyses using the Thermo Scientific™ iCAP TQ™ yielded an isochron slope 5× less precise than Proteus. We use an uncertainty model to illustrate the advantage of using Proteus over single collector CC-ICPMS/MS for in situ Rb–Sr dating. The results of this model show that the improvement is most marked for samples that have low Rb/Sr (<10) or are young (<100 Ma). We also report the first example of an in situ, internal Rb–Sr isochron from a single potassium-feldspar grain. Using a sample from the Shap granite, we obtained accurate age and initial (87)Sr/(86)Sr with 95% confidence intervals of ±1.5% and ±0.03% respectively. Such capabilities offer new opportunities in geochronological studies

Venous thromboembolism following colectomy for diverticular disease: an English population-based cohort study

AimThis study reports venous thromboembolism (VTE) rates following colectomy for diverticular disease to explore the magnitude of postoperative VTE risk in this population and identify high risk subgroups of interest. MethodEnglish national cohort study of colectomy patients between 2000 and 2019 using linked primary (Clinical Practice Research Datalink) and secondary (Hospital Episode Statistics) care data. Stratified by admission type, absolute incidence rates (IR) per 1000 person-years and adjusted incidence rate ratios (aIRR) were calculated for 30- and 90-day post-colectomy VTE. ResultsOf 24,394 patients who underwent colectomy for diverticular disease, over half (57.39%) were emergency procedures with the highest VTE rate seen in patients ≥70-years-old (IR 142.27 per 1000 person-years, 95%CI 118.32–171.08) at 30 days post colectomy. Emergency resections (IR 135.18 per 1000 person-years, 95%CI 115.72–157.91) had double the risk (aIRR 2.07, 95%CI 1.47–2.90) of developing a VTE at 30 days following colectomy compared to elective resections (IR 51.14 per 1000 person-years, 95%CI 38.30–68.27). Minimally invasive surgery (MIS) was shown to be associated with a 64% reduction in VTE risk (aIRR 0.36 95%CI 0.20–0.65) compared to open colectomies at 30 days post-op. At 90 days following emergency resections, VTE risks remained raised compared to elective colectomies. ConclusionFollowing emergency colectomy for diverticular disease, the VTE risk is approximately double compared to elective resections at 30 days while MIS was found to be associated with a reduced risk of VTE. This suggests advancements in postoperative VTE prevention in diverticular disease patients should focus on those undergoing emergency colectomies

Structural studies suggest aggregation as one of the modes of action for teixobactin

Teixobactin is a new promising antibiotic that targets cell wall biosynthesis by binding to lipid II and has no detectable resistance thanks to its unique but yet not fully understood mechanism of operation. To aid in the structure-based design of teixobactin analogues with improved pharmacological properties, we present a 3D structure of native teixobactin in membrane mimetics and characterise its binding to lipid II through a combination of solution NMR and fast (90 kHz) magic angle spinning solid state NMR. In NMR titrations, we observe a pattern strongly suggesting interactions between the backbone of the C-terminal “cage” and the pyrophosphate moiety in lipid II. We find that the N-terminal part of teixobactin does not only act as a membrane anchor, as previously thought, but is actively involved in binding. Moreover, teixobactin forms a well-structured and specific complex with lipid II, where the N-terminal part of teixobactin assumes a b conformation that is highly prone to aggregation, which likely contributes to the antibiotic's high bactericidal efficiency. Overall, our study provides several new clues to teixobactin's modes of action

Coffee and tea consumption in the early adult lifespan and left ventricular function in middle age: the CARDIA study

AIMS: The long-term impact of coffee or tea consumption on subclinical left ventricular (LV) systolic or diastolic function has not been previously studied. We examined the association between coffee or tea consumption beginning in early adulthood and cardiac function in midlife. METHODS AND RESULTS: We investigated 2735 Coronary Artery Risk Development in Young Adults (CARDIA) study participants with long-term total caffeine intake, coffee, and tea consumption data from three visits over a 20 year interval and available echocardiography indices at the CARDIA Year-25 exam (2010-2011). Linear regression models were used to assess the association between caffeine intake, tea, and coffee consumption (independent variables) and echocardiography outcomes [LV mass, left atrial volume, and global longitudinal strain (GLS), LV ejection fraction (LVEF), and transmitral Doppler early filling velocity to tissue Doppler early diastolic mitral annular velocity (E/e )]. Models were adjusted for standard cardiovascular risk factors, socioeconomic status, physical activity, alcohol use, and dietary factors (calorie intake, whole and refined grain intake, and fruit and vegetable consumption). Mean (standard deviation) age was 25.2 (3.5) years at the CARDIA Year-0 exam (1985-1986), 57.4% were women, and 41.9% were African-American. In adjusted multivariable linear regression models assessing the relationship between coffee consumption and GLS, beta coefficients when comparing coffee drinkers of \u3c 1, 1-2, 3-4, and \u3e 4 cups/day with non-coffee drinkers were beta = -0.30%, P \u3c 0.05; beta = -0.35%, P \u3c 0.05; beta = -0.32%, P \u3c 0.05; beta = -0.40%, P \u3e 0.05; respectively (more negative values implies better systolic function). In adjusted multivariable linear regression models assessing the relationship between coffee consumption and E/e , beta coefficients when comparing coffee drinkers of \u3c 1, 1-2, 3-4, and \u3e 4 cups/day with non-coffee drinkers were beta = -0.29, P \u3c 0.05; beta = -0.38, P \u3c 0.01; beta = -0.20, P \u3e .05; and beta = -0.37, P \u3e 0.05, respectively (more negative values implies better diastolic function). High daily coffee consumption ( \u3e 4 cups/day) was associated with worse LVEF (beta = -1.69, P \u3c 0.05). There were no associations between either tea drinking or total caffeine intake and cardiac function (P \u3e 0.05 for all). CONCLUSIONS: Low-to-moderate daily coffee consumption from early adulthood to middle age was associated with better LV systolic and diastolic function in midlife. High daily coffee consumption ( \u3e 4cups/day) was associated with worse LV function. There was no association between caffeine or tea intake and cardiac function

The ICON Trauma Study: The Impact of the COVID-19 lockdown on Major Trauma workload in the UK

BackgroundThe global pandemic caused by SARS-CoV-2 has impacted population health and care delivery worldwide. As information emerges regarding the impact of “lockdown measures” and changes to clinical practice worldwide; there is no comparative information emerging from the United Kingdom with regard to major trauma.MethodsThis observational study from a UK Major Trauma Centre matched a cohort of patients admitted during a 10-week period of the SARS-CoV-2-pandemic (09/03/2020–18/05/2020) to a historical cohort of patients admitted during a similar time period in 2019 (11/03/2019–20/05/2019). Differences in demographics, Clinical Frailty Scale, SARS-CoV-2 status, mechanism of injury and injury severity were compared using Fisher’s exact and Chi-squared tests. Univariable and multivariable logistic regression analyses examined the associated factors that predicted 30-days mortality.ResultsA total of 642 patients were included, with 405 in the 2019 and 237 in the 2020 cohorts, respectively. 4/237(1.69%) of patients in the 2020 cohort tested positive for SARS-CoV-2. There was a 41.5% decrease in the number of trauma admissions in 2020. This cohort was older (median 46 vs 40 years), had more comorbidities and were frail (p [less than] 0.0015). There was a significant difference in mechanism of injury with a decrease in vehicle related trauma, but an increase in falls. There was a twofold increased risk of mortality in the 2020 cohort which in adjusted multivariable models, was explained by injury severity and frailty. A positive SARS-CoV-2 status was not significantly associated with increased mortality when adjusted for other variables.ConclusionPatients admitted during the COVID-19 pandemic were older, frailer, more co-morbid and had an associated increased risk of mortality

Branch-recombinant Gaussian processes for analysis of perturbations in biological time series.

MOTIVATION: A common class of behaviour encountered in the biological sciences involves branching and recombination. During branching, a statistical process bifurcates resulting in two or more potentially correlated processes that may undergo further branching; the contrary is true during recombination, where two or more statistical processes converge. A key objective is to identify the time of this bifurcation (branch or recombination time) from time series measurements, e.g. by comparing a control time series with perturbed time series. Gaussian processes (GPs) represent an ideal framework for such analysis, allowing for nonlinear regression that includes a rigorous treatment of uncertainty. Currently, however, GP models only exist for two-branch systems. Here, we highlight how arbitrarily complex branching processes can be built using the correct composition of covariance functions within a GP framework, thus outlining a general framework for the treatment of branching and recombination in the form of branch-recombinant Gaussian processes (B-RGPs). RESULTS: We first benchmark the performance of B-RGPs compared to a variety of existing regression approaches, and demonstrate robustness to model misspecification. B-RGPs are then used to investigate the branching patterns of Arabidopsis thaliana gene expression following inoculation with the hemibotrophic bacteria, Pseudomonas syringae DC3000, and a disarmed mutant strain, hrpA. By grouping genes according to the number of branches, we could naturally separate out genes involved in basal immune response from those subverted by the virulent strain, and show enrichment for targets of pathogen protein effectors. Finally, we identify two early branching genes WRKY11 and WRKY17, and show that genes that branched at similar times to WRKY11/17 were enriched for W-box binding motifs, and overrepresented for genes differentially expressed in WRKY11/17 knockouts, suggesting that branch time could be used for identifying direct and indirect binding targets of key transcription factors. AVAILABILITY AND IMPLEMENTATION: https://github.com/cap76/BranchingGPs. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online