Endonuclease controlled aggregation of gold nanoparticles for the ultrasensitive detection of pathogenic bacterial DNA

The development of an ultrasensitive biosensor for the low-cost and on-site detection of pathogenic DNA could transform detection capabilities within food safety, environmental monitoring and clinical diagnosis. Herein, we present an innovative approach exploiting endonuclease-controlled aggregation of plasmonic gold nanoparticles (AuNPs) for label-free and ultrasensitive detection of bacterial DNA. The method utilizes RNA-functionalized AuNPs which form DNA-RNA heteroduplex structures through specific hybridization with target DNA. Once formed, the DNA-RNA heteroduplex is susceptible to RNAse H enzymatic cleavage of the RNA probe, allowing the target DNA to liberate and hybridize with another RNA probe. This continuously happens until all of the RNA probes are cleaved, leaving the nanoparticles unprotected and thus aggregated upon exposure to a high electrolytic medium. The assay is ultrasensitive, allowing the detection of target DNA at femtomolar level by simple spectroscopic analysis (40.7 fM and 2.45 fM as measured by UV-vis and dynamic light scattering (DLS), respectively). The target DNA spiked food matrix (chicken meat) is also successfully detected at a concentration of 1.2 pM (by UV-vis) or 18.0 fM (by DLS). In addition to the ultra-high sensitivity, the total analysis time of the assay is less than 3 hours, thus demonstrating its practicality for food analysis

T. brucei cathepsin-L increases arrhythmogenic sarcoplasmic reticulum-mediated calcium release in rat cardiomyocytes

Aims: African trypanosomiasis, caused by Trypanosoma brucei species, leads to both neurological and cardiac dysfunction and can be fatal if untreated. While the neurological-related pathogenesis is well studied, the cardiac pathogenesis remains unknown. The current study exposed isolated ventricular cardiomyocytes and adult rat hearts to T. brucei to test whether trypanosomes can alter cardiac function independent of a systemic inflammatory/immune response. Methods and results: Using confocal imaging, T. brucei and T. brucei culture media (supernatant) caused an increased frequency of arrhythmogenic spontaneous diastolic sarcoplasmic reticulum (SR)-mediated Ca2+ release (Ca2+ waves) in isolated adult rat ventricular cardiomyocytes. Studies utilising inhibitors, recombinant protein and RNAi all demonstrated that this altered SR function was due to T. brucei cathepsin-L (TbCatL). Separate experiments revealed that TbCatL induced a 10–15% increase of SERCA activity but reduced SR Ca2+ content, suggesting a concomitant increased SR-mediated Ca2+ leak. This conclusion was supported by data demonstrating that TbCatL increased Ca2+ wave frequency. These effects were abolished by autocamtide-2-related inhibitory peptide, highlighting a role for CaMKII in the TbCatL action on SR function. Isolated Langendorff perfused whole heart experiments confirmed that supernatant caused an increased number of arrhythmic events. Conclusion: These data demonstrate for the first time that African trypanosomes alter cardiac function independent of a systemic immune response, via a mechanism involving extracellular cathepsin-L-mediated changes in SR function

Novel electrochemical systems for asymmetric oxidation

Organic reactions, which can be carried out in water and in the absence of heavy metals, are becoming more important today due to concerns over safety and environmental impact. Thus if an oxidation reaction can be carried out, where the oxidant is generated in-situ using electrolysis, then this is advantageous over existing systems that use strong or large volumes of stoichiometric oxidant and solvent, that cannot be recycled. In this thesis a wide variety of conditions and methods for producing enantiomerically enriched epoxides and sulfoxides have been reported using both electrochemically generated percarbonate and hypochlorite. It has been possible to carry out a range of oxidation reactions both as a one-pot reaction and with the oxidant generated in a batch process. Carrying out sulfoxidation reactions as a batch process with a carbonate solution it is possible to obtain ees of 20%. Using our in-situ generation of oxidant, as a one-pot electrochemical reaction, has provided a wide range of sulfoxides in good to excellent yield, with the application of this system to the oxidation of alkenes using a chiral iminium salt resulting in 100% conversion, with up to 44% ee

Women’s Resistance: Patient Pathographies and Medical Authority

In recent years, illness narratives have risen in popularity. Women’s medical narratives in particular have gained momentum in the literary world, and they often share commonalities including the inherent theme of medical resistance and an emphasis on the power dynamic between patients and physicians. This thesis will examine two pathographies, Susanna Kaysen’s Girl, Interrupted and Porochista Khakpour’s Sick, in the contexts of gender and disability studies, as well as theories of illness narratives. I examine how each text resists medical authority, and I also closely survey the physician-patient relationships within each text. The themes of gender and disability emerge in both Khakpour’s and Kaysen’s texts, but in other ways the texts approach illness differently. Using documents from her institutionalization in the 1960s, Kaysen humanizes her fellow patients and challenges medical authority using humor. In contrast, Khakpour uses a storytelling mode, emphasizing location and dislocation and the importance of her Iranian immigrant status and drug addiction to her experience of Lyme disease. These pathographies challenge medical authority through personal narrative

Predicting College Students' Food Intake With Measures of Executive Functioning

The purpose of this study was to investigate how, and to what extent, dimensions of executive functioning (EF) predict college students' food intake based on US Department of Agriculture's proportion food groups, namely, fruits, vegetables, grains, dairy, protein, and fats/sweets. Ninety-eight participants were administered a self-report EF measure, the Behavior Rating Inventory of Executive Function-Adult Version (BRIEF-A; Guy, Isquith, & Gioia, 2005), which assesses EF behavior regulation and metacognitive skills. In addition, two clinical measures of EF were administered, the Tempe Sorting Task (Marshall, Wodrich, & Gorin, 2009), a measure of EF inhibition, and Digit Span, which is a working memory subtest of the Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV; Wechsler, 2008). To obtain a measure of food intake, participants were also administered the Personal Wellness Profile (PWP; Wellsource Inc., 1998). Results indicated that self-ratings of EF behavior regulation and metacognitive skills successfully predicted food intake scores. EF metacognitive skills appeared to be a better predictor of food intake when compared to EF behavior regulation. In comparison to the predictive ability of the EF rating scale, the clinical measures were not associated with food intake. There was an absence of significant added value of EF clinical measures when rating scale scores already existed.M.A

Tracing ingestion of 'novel' foods in UK diets for possible health surveillance: a feasibility study

Objective: To investigate the feasibility of using commercially available data on household food consumption to carry out food and nutritional surveillance. Design: Taylor Nelson Sofres (TNS) collects information on foods brought home for consumption among a representative quota sample of the British population. In total, 33 177 households and 105 667 individuals provided data between 1991 and 2000. These were used to investigate sociodemographic, geographical and temporal trends in purchase patterns of the main macronutrients and four groups of marker products. Results: Sociodemographic characteristics of the TNS sample were broadly consistent with those of the British population. Estimated energy intakes were slightly low (1667 +/- 715 kcal) in comparison with other national data. However, percentage energy contributions were consistent with national trends: e.g. consumption of alcohol in the home increased between 1991 and 2000 with higher intakes among more affluent households, while fat intakes decreased slightly over the same period. Significant temporal, geographic and socio-economic trends were found for all nutrients (P < 0.0001). Intakes of marker products were sparse (purchased by < 4% of households), but significant variations were detected in the proportion of households purchasing some or all of the marker products across temporal, geographic and socio-economic strata. Conclusions: A prospective nutrient surveillance system could be used to trace consumption patterns of foods or nutrients to inform nutritional surveillance. However, existing data sources would require a number of modifications to increase their suitability for such a project. Increasing surveillance to consider ingredients would require the development of a central coding system, with electronically linked barcode, ingredient and nutrient information

Evaluation of an Inexpensive Growth Medium for Direct Detection of Escherichia coli in Temperate and Sub-Tropical Waters

The cost and complexity of traditional methods for the detection of faecal indicator bacteria, including E. coli, hinder widespread monitoring of drinking water quality, especially in lowincome countries and outside controlled laboratory settings. In these settings the problem is exacerbated by the lack of inexpensive media for the detection of E. coli in drinking water. We developed a new low-cost growth medium, aquatest (AT), and validated its use for the direct detection of E. coli in temperate and sub-tropical drinking waters using IDEXX QuantiTray1. AT was compared with IDEXX Colilert-181 and either EC-MUG or MLSB for detecting low levels of E. coli from water samples from temperate (n = 140; Bristol, UK) and subtropical regions (n = 50, Pretoria/Tshwane, South Africa). Confirmatory testing (n = 418 and 588, respectively) and the comparison of quantitative results were used to assess performance. Sensitivity of AT was higher than Colilert-181 for water samples in the UK [98.0% vs. 86.9%; p<0.0001] and South Africa [99.5% vs. 93.2%; p = 0.0030]. There was no significant difference in specificity, which was high for both media (>95% in both settings). Quantitative results were comparable and within expected limits. AT is reliable and accurate for the detection of E. coli in temperate and subtropical drinking water. The composition of the new medium is reported herein and can be used freely

Atrial-like cardiomyocytes from human pluripotent stem cells are a robust preclinical model for assessing atrial-selective pharmacology

Drugs targeting atrial-specific ion channels, K(v)1.5 or K(ir)3.1/3.4, are being developed as new therapeutic strategies for atrial fibrillation. However, current preclinical studies carried out in non-cardiac cell lines or animal models may not accurately represent the physiology of a human cardiomyocyte (CM). In the current study, we tested whether human embryonic stem cell (hESC)-derived atrial CMs could predict atrial selectivity of pharmacological compounds. By modulating retinoic acid signaling during hESC differentiation, we generated atrial-like (hESC-atrial) and ventricular-like (hESC-ventricular) CMs. We found the expression of atrial-specific ion channel genes, KCNA5 (encoding Kv1.5) and KCNJ3 (encoding K-ir 3.1), in hESC-atrial CMs and further demonstrated that these ion channel genes are regulated by COUP-TF transcription factors. Moreover, in response to multiple ion channel blocker, vernakalant, and K(v)1.5 blocker, XEN-D0101, hESC-atrial but not hESC-ventricular CMs showed action potential (AP) prolongation due to a reduction in early repolarization. In hESC-atrial CMs, XEN-R0703, a novel K(ir)3.1/3.4 blocker restored the AP shortening caused by CCh. Neither CCh nor XEN-R0703 had an effect on hESC-ventricular CMs. In summary, we demonstrate that hESC-atrial CMs are a robust model for pre-clinical testing to assess atrial selectivity of novel antiarrhythmic drugs