Surface plasmon resonance (SPR) is a popular real-time technique for the measurement of binding affinity and kinetics, and bench-top instruments combine affordability and ease of use with other ...benefits of the technique. Biomolecular ligands labeled with the 6xHis tag can be immobilized onto sensing surfaces presenting the Ni
-nitrilotriacetic acid (NTA) functional group. While Ni-NTA immobilization offers many advantages, including the ability to regenerate and reuse the sensors, its use can lead to signal variability between experimental replicates. We report here a study of factors contributing to this variability using the Nicoya OpenSPR as a model system and suggest ways to control for those factors, increasing the reproducibility and rigor of the data. Our model ligand/analyte pairs were two ovarian cancer biomarker proteins (MUC16 and HE4) and their corresponding monoclonal antibodies. We observed a broad range of non-specific binding across multiple NTA chips. Experiments run on the same chips had more consistent results in ligand immobilization and analyte binding than experiments run on different chips. Further assessment showed that different chips demonstrated different maximum immobilizations for the same concentration of injected protein. We also show a variety of relationships between ligand immobilization level and analyte response, which we attribute to steric crowding at high ligand concentrations. Using this calibration to inform experimental design, researchers can choose protein concentrations for immobilization corresponding to the linear range of analyte response. We are the first to demonstrate calibration and normalization as a strategy to increase reproducibility and data quality of these chips. Our study assesses a variety of factors affecting chip variability, addressing a gap in knowledge about commercially available sensor chips. Controlling for these factors in the process of experimental design will minimize variability in analyte signal when using these important sensing platforms.
Purpose: This study provides preliminary evidence for the acceptability, reliability, and validity of the new Alzheimer's Disease Knowledge Scale (ADKS), a content and psychometric update to the ...Alzheimer's Disease Knowledge Test. Design and Methods: Traditional scale development methods were used to generate items and evaluate their psychometric properties in a variety of subsamples. Results: The final 30-item, true/false scale takes approximately 5–10 min to complete and covers risk factors, assessment and diagnosis, symptoms, course, life impact, caregiving, and treatment and management. Preliminary results suggest that the ADKS has adequate reliability (test–retest and internal consistency) and validity (content, predictive, concurrent, and convergent). Implications: The ADKS is designed for use in both applied and research contexts, capable of assessing knowledge about Alzheimer's disease among laypeople, patients, caregivers, and professionals.
We report the development of a novel laser absorption diagnostic for accurate, time-resolved and in situ measurement of various hydrocarbon fuels in combustion systems. This diagnostic method ...utilized a wavelength-tunable interband cascade laser operated near 3.41 µm, providing improved performance in several aspects over the conventional 3.39-μm He–Ne gas laser diagnostic. First, it enabled a simplified and more compact experimental setup that significantly reduced the measurement complexity. Second, it improved the long-term stability over the 3.39-μm diagnostic by at least a factor of 2, leading to substantially reduced measurement uncertainties. Lastly, the new diagnostic also avoided a cluster of CH4 transitions that coincide with the He–Ne wavelength, and hence minimized CH4 interference in other hydrocarbon measurements. Absorption cross-sections of a variety of hydrocarbons at both 3.39 and 3.41 µm were measured in a high-purity shock tube over 531–1659 K, 0.34–3.1 atm, and reported here as functions of temperature. Example applications of this new diagnostic in shock tube pyrolysis studies of methylcyclohexane, n-heptane and iso-octane are also presented. These studies have yielded an improved value of the overall decomposition rate constant of methylcyclohexane as kd = 3.3 × 1015 exp(−38000 K/T) s−1 + 28%/−34%, which is valid over 1260–1400 K and near 1.5 atm.
Transition metal-catalyzed aerobic alcohol oxidation is an attractive method for the synthesis of carbonyl compounds, but most catalytic systems feature precious metals and require pure oxygen. The ...vanadium complex (HQ)2VV(O)(OiPr) (2 mol %, HQ = 8-quinolinate) and NEt3 (10 mol %) catalyze the oxidation of benzylic, allylic, and propargylic alcohols with air. The catalyst can be easily prepared under air using commercially available reagents and is effective for a wide range of primary and secondary alcohols.
The prevalence of metabolic syndrome in COPD patients and its impact on patient related outcomes has been little studied. We evaluated the prevalence of metabolic syndrome and clinical and functional ...characteristics in patients with COPD and healthy subjects.
228 COPD patients and 156 healthy subjects were included. Metabolic syndrome was defined using criteria of the IDF. In all patients spirometry, body composition, functional exercise performance, and mood and health status were assessed. Groups were stratified for BMI and gender.
Metabolic syndrome was present in 57% of the COPD patients and 40% of the healthy subjects. After stratification for BMI, presence of metabolic syndrome in patients with a BMI ≥25 kg/m2 was higher than in healthy peers. Patients with metabolic syndrome and a BMI <25 kg/m2 had higher BMI, fat free mass index and bone mineral density, and a lower 6MWD than the BMI matched patients without metabolic syndrome. Spirometry, maximal ergometry, mood and health status, and blood gases were not different between those groups. In COPD patients with metabolic syndrome self-reported co-morbidities and medication use were higher than in those without.
Metabolic syndrome is more prevalent in overweight or obese COPD patients than in BMI matched healthy subjects. Metabolic syndrome did not additionally impact patients' functional outcomes, but did impact the prevalence of co-morbidities.
Rhinovirus (RV) infections trigger asthma exacerbations. Genome-wide expression analysis of RV1A-infected primary bronchial epithelial cells from normal and asthmatic donors was performed to ...determine whether asthma is associated with a unique pattern of RV-induced gene expression. Virus replication rates were similar in cells from normal and asthmatic donors. Overall, RV downregulated 975 and upregulated 69 genes. Comparisons of transcriptional profiles generated from microarrays and confirmed by quantitative reverse transcription PCR and cluster analysis showed some up- and downregulated genes in asthma cells involved in immune responses (IL1B, IL1F9, IL24, and IFI44) and airway remodeling (LOXL2, MMP10, FN1). Notably, most of the asthma-related differences in RV-infected cells were also present in the cells before infection. These findings suggest that differences in RV-induced gene expression profiles of cells from normal and mild asthmatic subjects could affect the acute inflammatory response to RV, and subsequent airway repair and remodeling.
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