341 research outputs found

    Assembly and structure of α-helical peptide films on hydrophobic fluorocarbon surfaces

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    The structure, orientation and formation of amphiphilic α-helix model peptide films on fluorocarbon surfaces has been monitored with sum frequency generation (SFG) vibrational spectroscopy, near edge X-ray absorption fine structure (NEXAFS) spectroscopy and X-ray photoelectron spectroscopy (XPS). The α-helix peptide is a 14-mer of hydrophilic lysine and hydrophobic leucine residues with a hydrophobic periodicity of 3.5. This periodicity yields a rigid amphiphilic peptide with leucine and lysine side chains located on opposite sides. XPS composition analysis confirms the formation of a peptide film that covers about 75% of the surface. NEXAFS data are consistent with chemically intact adsorption of the peptides. A weak linear dichroism of the amide π* is likely due to the broad distribution of amide bond orientations inherent to the α-helical secondary structure. SFG spectra exhibit strong peaks near 2865 cm(−1) and 2935 cm(−1) related to aligned leucine side chains interacting with the hydrophobic surface. Water modes near 3200 cm(−1) and 3400 cm(−1) indicate ordering of water molecules in the adsorbed--peptide fluorocarbon surface interfacial region. Amide I peaks observed near 1655 cm(−1) confirm that the secondary structure is preserved in the adsorbed peptide. A kinetic study of the film formation process using XPS and SFG showed rapid adsorption of the peptides followed by a longer assembly process. Peptide SFG spectra taken at the air–buffer interface showed features related to well ordered peptide films. Moving samples through the buffer surface led to the transfer of ordered peptide films onto the substrates

    Baseline anticholinergic burden from medications predicts incident fatal and non-fatal stroke in the EPIC-Norfolk general population.

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    BACKGROUND: Stroke is primarily a disease of older age, with a substantial impact on global mortality and morbidity. Medications with anticholinergic effects are widely used, but no studies have been conducted to examine the relationship between anticholinergic burden (ACB) and stroke in a general population. METHOD: The sample was drawn from the EPIC-Norfolk cohort. Baseline assessments were carried out during 1993-97 and participants were followed up until March 2016. Participants were divided into four groups according to their total ACB score at baseline; these groups were those with a total ACB score of 0, 1, 2-3 and >3. After exclusion, Cox proportional hazards models were constructed to determine the associations between the ACB score groups and the risk of incident stroke and stroke mortality. Sensitivity analysis and propensity score matched analyses were performed. RESULTS: In total 25 639 participants attended the first health check; 3917 participants were excluded, leaving 21 722 participants to be included. Participants had a mean age [standard deviation (SD)] of 58.9 (9.2) years (54.4% women). Of these, 2131 suffered incident stroke and 562 died from stroke. Mean follow-up was approximately 18 years for both outcomes. In the fully adjusted model, those with an ACB of >3 had 59% relative risk of incident stroke {hazard ratio [HR] [95% confidence interval (CI) 1.59 [1.34-1.89]} and 86% relative risk of stroke mortality [1.86 (1.37-2.53)] compared with those in ACB 0 category. Sensitivity analyses and propensity score matched analyses showed similar results. CONCLUSIONS: Our results provide an incentive for the cautious use of medications with anticholinergic properties, to help reduce the global burden of stroke

    Hypertensive Disorders of Pregnancy (HDP) and the Risk of Common Cancers in Women: Evidence from the European Prospective Investigation into Cancer (EPIC)-Norfolk Prospective Population-Based Study.

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    PURPOSE: The purpose was to determine the association between HDP and cancer in a UK cohort. METHODS: Between 1993 and 1997, participants from the EPIC-Norfolk cohort attended baseline health-checks and completed questionnaires, where a history of HDP was collected. Incident cancer cases were identified through NHS record linkage until March 2016. Univariable and multivariable logistic regression analyses were employed to determine the association between HDP and odds of cancer, with adjustment for potential confounders including co-morbidities, sociodemographic, lifestyle and reproductive factors. RESULTS: 13,562 women were included after excluding prevalent cancer cases and women with no pregnancies. 2919 (21.5%) reported HDP and 2615 incident cancers occurred during mean follow up of 19 years. Median age (IQR) at baseline for incident cancer was 60.8 (±14.8) years. Among incident cancer cases, 578 (22.1%) had HDP. In multivariable analyses, HDP had odds ratio (OR) 1.06; 95% CI 0.95-1.18 for incident cancer. The ORs (95% CIs) for common site-specific cancers including breast, colorectal, lung, ovarian and endometrial cancers were 1.06 (0.88-1.28), 1.15 (0.92-1.45), 0.96 (0.68-1.35), 1.30 (0.93-1.83) and 1.16 (0.80-1.67). CONCLUSION: We found no association between HDP and cancer risk. Further studies are required to confirm and account for any underlying genetic factors involved in pregnancy-related exposures and cancer risk

    Country-level determinants of the severity of the first global wave of the COVID-19 pandemic : an ecological study

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    Acknowledgements We would like to thank Dr Kathryn Martin, who provided valuable advice in study design. Funding This work was supported by the Aberdeen Clinical Academic Training Scheme.Peer reviewedPublisher PD

    Nano-Socketed Nickel Particles with Enhanced Coking Resistance Grown \u3cem\u3ein situ\u3c/em\u3e by Redox Exsolution

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    Metal particles supported on oxide surfaces are used as catalysts for a wide variety of processes in the chemical and energy conversion industries. For catalytic spplications, metal particles are generally formed on an oxide support by physical or chemical deposition, or less commonly by exsolution from it. Although fundamentally different, both methods might be assumed to produce morphologically and functionally similar particles. Here we show that unlike nickel particles deposited on perovskite oxides, exsolved analogues are socketed into the parent perovskite, leading to enhanced stability and a significant decrease in the propensity for hydrocarbon coking, indicative of a stronger metal-oxide interface. In addition, we reveal key surface effects and defect interactions critical for future design of exsolution-based perovskite materials for catalytic and other functionalities. This study provides a new dimenstion for tailoring particle-substrate interactions in the context of increasing interest for emergent interfactial phenomena

    Does prior antithrombotic therapy influence recurrence and bleeding risk in stroke patients with atrial fibrillation or atrial flutter?

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    The authors would like to thank the patients of the NNUH Stroke Register cohort and the data team of the Norfolk and Norwich University Stroke Services. NNUH Stroke Register is maintained by the NNUH Stroke Services.Peer reviewedPostprin

    Cardiovascular and Noncardiovascular Prescribing and Mortality After Takotsubo:Comparison With Myocardial Infarction and General Population

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    BACKGROUND: Takotsubo syndrome is an increasingly common cardiac emergency with no known evidence-based treatment.OBJECTIVES: To investigate cardiovascular mortality and medication use after takotsubo syndrome.METHODS: In a case-control study, all patients with takotsubo syndrome in Scotland between 2010-2017 (n=620) were age, sex and geographically matched to individuals in the general population (1:4, n=2,480) and contemporaneous patients with acute myocardial infarction (1:1, n=620). Electronic health record data linkage of mortality outcomes and drug prescribing were analysed using Cox proportional hazard regression models.RESULTS: Of the 3,720 study participants (mean age, 66 years; 91% women), 153 (25%) patients with takotsubo syndrome died over the median of 5.5 years follow up. This exceeded mortality rates in the general population [374 (15%)]; hazard ratio [HR] 1.78 [95% confidence interval 1.48-2.15], P<0.0001), especially for cardiovascular (HR 2.47, [1.81-3.39], P<0.001) but also non-cardiovascular (HR 1.48 [1.16-1.87], P=0.002) deaths. Mortality rates were lower for patients with takotsubo syndrome than those with myocardial infarction (31%, 195/620; HR 0.76 [0.62-0.94], P=0.012), which was attributable to lower rates of cardiovascular (HR 0.61 [0.44-0.84], P=0.002) but not non-cardiovascular (HR 0.92 [0.69-1.23], P=0.59) deaths. Despite comparable medications use, cardiovascular therapies were consistently associated with better survival in patients with myocardial infarction but not in those with takotsubo syndrome. Diuretic (P=0.01), anti-inflammatory (P=0.002) and psychotropic (P<0.001) therapies were all associated with worse outcomes in patients with takotsubo syndrome.CONCLUSIONS: In patients with takotsubo syndrome, cardiovascular mortality is the leading cause of death, and this is not associated with cardiovascular therapy use

    Extreme genetic fragility of the HIV-1 capsid

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    Genetic robustness, or fragility, is defined as the ability, or lack thereof, of a biological entity to maintain function in the face of mutations. Viruses that replicate via RNA intermediates exhibit high mutation rates, and robustness should be particularly advantageous to them. The capsid (CA) domain of the HIV-1 Gag protein is under strong pressure to conserve functional roles in viral assembly, maturation, uncoating, and nuclear import. However, CA is also under strong immunological pressure to diversify. Therefore, it would be particularly advantageous for CA to evolve genetic robustness. To measure the genetic robustness of HIV-1 CA, we generated a library of single amino acid substitution mutants, encompassing almost half the residues in CA. Strikingly, we found HIV-1 CA to be the most genetically fragile protein that has been analyzed using such an approach, with 70% of mutations yielding replication-defective viruses. Although CA participates in several steps in HIV-1 replication, analysis of conditionally (temperature sensitive) and constitutively non-viable mutants revealed that the biological basis for its genetic fragility was primarily the need to coordinate the accurate and efficient assembly of mature virions. All mutations that exist in naturally occurring HIV-1 subtype B populations at a frequency >3%, and were also present in the mutant library, had fitness levels that were >40% of WT. However, a substantial fraction of mutations with high fitness did not occur in natural populations, suggesting another form of selection pressure limiting variation in vivo. Additionally, known protective CTL epitopes occurred preferentially in domains of the HIV-1 CA that were even more genetically fragile than HIV-1 CA as a whole. The extreme genetic fragility of HIV-1 CA may be one reason why cell-mediated immune responses to Gag correlate with better prognosis in HIV-1 infection, and suggests that CA is a good target for therapy and vaccination strategies
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