Case study: Co-creating a flipped feed-in approach to a virtual biochemistry lab assessment: increasing student achievement and engagement in a large, diverse cohort.

More inclusive, authentic assessments are required to address awarding gaps and to ensure that bioscience students can apply their knowledge to relevant work-based scenarios. In this case report, we present a co-created approach to designing a more inclusive, virtual biochemistry lab assessment for a diverse cohort of ∼270 first-year students. The assignment was to write up an inclusive clinical case study as a one-page journal article. A flipped classroom approach taught the relevant skills, along with simulated labs from Learning Science Ltd. Student Lecturers co-created the assessment, including the marking rubric and the unexemplars. We replaced traditional feedback with a flipped, feed-in approach where students were able to engage in a formative assessment with peer marking and unexemplars. Whilst the summative assessment was marked anonymously, a dialogue-based approach was employed, where students could request personalised audio feed-forward from the tutor. The high pass rate (97%) and student satisfaction score (88%) suggest that this approach is an effective way to challenge, engage and support a large, diverse cohort of students. First-year students who participated in the flipped feed-in experience obtained a significantly higher summative mark (56.7% cf. 50.9%) than those who did not. Interestingly, students in receipt of learning adjustments scored higher marks on average in the summative assessment (59.3% cf. 54.3%), suggesting that we have reversed the disability-based attainment gap. Further investigation into whether a co-created, flipped feed-in approach can reduce attainment gaps based on ethnicity, gender and age is warranted.

Olfactory Dysfunction as a Global Biomarker for Sniffing out Alzheimer's Disease: A Meta-Analysis.

Cases of Alzheimer's disease (AD) are rising exponentially due to increasing global life expectancy. There are approximately 50 million sufferers worldwide, with prevalence rising most rapidly in low-income countries such as Africa and Asia. There is currently no definite diagnosis of AD until after death, thus an early biomarker for AD is urgently required in order to administer timelier and more effective interventions. Olfactory dysfunction (problems with the sense of smell) is one of the earliest, preclinical symptoms observed in AD. Olfaction is a promising early biomarker for use worldwide as it is easy, cheap to measure, and not reliant on specialist clinicians or laboratory analysis. We carried out a meta-analysis to determine the credibility of olfaction in diagnosing AD in the preclinical stages, by comparing olfaction in healthy controls against AD patients and patients with mild cognitive impairment (MCI). Data from 10 articles were subjected to two comparative meta-analyses. In the case of AD, the results illustrated that the overall magnitude of effect size was more apparent, d = -1.63, 95% CI [-1.95, -1.31], in comparison to that of MCI, d = -0.81, 95% CI [-1.08, -0.55]. This shows that olfaction worsens progressively as patients progress from MCI to AD, highlighting the potential for olfactory dysfunction to identify AD in the preclinical stages prior to MCI.

Amyloid-ß Receptors: The Good, the Bad, and the Prion Protein.

Several different receptor proteins have been identified that bind monomeric, oligomeric, or fibrillar forms of amyloid-ß (Aß). "Good" receptors internalize Aß or promote its transcytosis out of the brain, whereas "bad" receptors bind oligomeric forms of Aß that are largely responsible for the synapticloss, memory impairments, and neurotoxicity that underlie Alzheimer disease. The prion protein both removes Aß from the brain and transduces the toxic actions of Aß. The clustering of distinct receptors in cell surface signaling platforms likely underlies the actions of distinct oligomeric species of Aß. These Aß receptor-signaling platforms provide opportunities for therapeutic intervention in Alzheimer disease.

CEA-targeted nanoparticles allow specific in vivo fluorescent imaging of colorectal cancer models.

Fluorescent imaging of colorectal tumor cells would improve tumor localization and allow intra-operative staging, facilitating stratification of surgical resections thereby improving patient outcomes. We aimed to develop and test fluorescent nanoparticles capable of allowing this in vivo. Dye-doped silica nanoparticles were synthesized. Anti-CEA (carcinoembryonic antigen) or control IgGs were conjugated to nanoparticles using various chemical strategies. Binding of CEA-targeted or control nanoparticles to colorectal cancer cells was quantified in vitro, and in vivo after systemic-delivery to murine xenografts. CEA-targeted, polyamidoamine dendrimer-conjugated, nanoparticles, but not control nanoparticles, allowed strong tumor-specific imaging. We are the first to demonstrate live, specific, in vivo imaging of colorectal cancer cells using antibody-targeted fluorescent nanoparticles. These nanoparticles have potential to allow intra-operative fluorescent visualization of tumor cells.

Biosensors for whole-cell bacterial detection.

Bacterial pathogens are important targets for detection and identification in medicine, food safety, public health, and security. Bacterial infection is a common cause of morbidity and mortality worldwide. In spite of the availability of antibiotics, these infections are often misdiagnosed or there is an unacceptable delay in diagnosis. Current methods of bacterial detection rely upon laboratory-based techniques such as cell culture, microscopic analysis, and biochemical assays. These procedures are time-consuming and costly and require specialist equipment and trained users. Portable stand-alone biosensors can facilitate rapid detection and diagnosis at the point of care. Biosensors will be particularly useful where a clear diagnosis informs treatment, in critical illness (e.g., meningitis) or to prevent further disease spread (e.g., in case of food-borne pathogens or sexually transmitted diseases). Detection of bacteria is also becoming increasingly important in antibioterrorism measures (e.g., anthrax detection). In this review, we discuss recent progress in the use of biosensors for the detection of whole bacterial cells for sensitive and earlier identification of bacteria without the need for sample processing. There is a particular focus on electrochemical biosensors, especially impedance-based systems, as these present key advantages in terms of ease of miniaturization, lack of reagents, sensitivity, and low cost.

A label-free electrical impedimetric biosensor for the specific detection of Alzheimer's amyloid-beta oligomers.

Alzheimer's disease (AD) is the most common form of dementia, with over 37 million sufferers worldwide and a global cost of over $600 billion. There is currently no cure for AD and no reliable method of diagnosis other than post-mortem brain examination. The development of a point-of-care test for AD is an urgent requirement in order to provide earlier diagnosis and, thus, useful therapeutic intervention. Here, we present a novel, label-free impedimetric biosensor for the specific detection of amyloid-beta oligomers (AßO), which are the primary neurotoxic species in AD. AßO have been proposed as the best biomarker for AD and levels of AßO in the blood have been found to correlate with cerebrospinal fluid load. The biorecognition element of our biosensor is a fragment of the cellular prion protein (PrP(C), residues 95-110), a highly expressed synaptic protein which mediates the neuronal binding and toxicity of AßO. During the layer-by-layer sensor construction, biotinylated PrP(C) (95-110) was attached via a biotin/NeutrAvidin bridge to polymer-functionalised gold screen-printed electrodes. Electrochemical impedance spectroscopy (EIS), cyclic voltammetry and scanning electron microscopy were used to validate biosensor assembly and functionality. EIS was employed for biosensor interrogation in the presence of Aß oligomers or monomers. The biosensor was specific for the detection of synthetic AßO and gave a linear response, without significant detection of monomeric Aß, down to an equivalent AßO concentration of ~0.5 pM. The biosensor was also able to detect natural, cell-derived AßO present in conditioned medium. The eventual commercialisation of this biosensor system could allow for the early diagnosis and disease monitoring of AD.

Novel impedimetric immunosensor for detection of pathogenic bacteria Streptococcus pyogenes in human saliva.

Streptococcus pyogenes , also known as group A streptococcus (GAS), is a Gram positive human pathogen responsible for invasive and noninvasive human infections with a high incidence rate. Traditional detection methods involve cell culture and PCR, which are limited by long processing times or the need for high cost equipment. Impedance-based electrochemical immunosensors provide an alternative by which precise and rapid quantitative detection of the organism can help with rapid clinical decisions. To bring a biosensor for point-of-care applications to market, strict optimization of each level of construction and operation is required. In this paper, commercial screen-printed gold electrodes have been used to construct polytyramine (Ptyr)-based immunosensors. Biotin tagged whole antibodies against S. pyogenes were conjugated to Ptyr amine group via biotin-NeutrAvidin coupling. Sensors were optimized at each level of construction, particularly for Ptyr electrodeposition and antibody concentration, to optimize signal and specificity. Scanning electron microscopy, fluorescence microscopy, and on-sensor analysis (HRP conjugated enhanced chemiluminescence-based semiquantitative method) to detect Ptyr surface amine and bound antibody were performed as supporting techniques. Cumulative and single shot incubations had shown detection range of 100 to 10(5) cells per 10 µL and 100 to 10(4) cells per 10 µL of bacteria in PBS, respectively. Sensors were also able to specifically detect S. pyogenes in 50% (v/v) human saliva, with good selectivity and low cross-reactivity.

Prion protein-mediated toxicity of amyloid-ß oligomers requires lipid rafts and the transmembrane LRP1.

Soluble oligomers of the amyloid-ß (Aß) peptide cause neurotoxicity, synaptic dysfunction, and memory impairments that underlie Alzheimer disease (AD). The cellular prion protein (PrP(C)) was recently identified as a high affinity neuronal receptor for Aß oligomers. We report that fibrillar Aß oligomers recognized by the OC antibody, which have been shown to correlate with the onset and severity of AD, bind preferentially to cells and neurons expressing PrP(C). The binding of Aß oligomers to cell surface PrP(C), as well as their downstream activation of Fyn kinase, was dependent on the integrity of cholesterol-rich lipid rafts. In SH-SY5Y cells, fluorescence microscopy and co-localization with subcellular markers revealed that the Aß oligomers co-internalized with PrP(C), accumulated in endosomes, and subsequently trafficked to lysosomes. The cell surface binding, internalization, and downstream toxicity of Aß oligomers was dependent on the transmembrane low density lipoprotein receptor-related protein-1 (LRP1). The binding of Aß oligomers to cell surface PrP(C) impaired its ability to inhibit the activity of the ß-secretase BACE1, which cleaves the amyloid precursor protein to produce Aß. The green tea polyphenol (-)-epigallocatechin gallate and the red wine extract resveratrol both remodeled the fibrillar conformation of Aß oligomers. The resulting nonfibrillar oligomers displayed significantly reduced binding to PrP(C)-expressing cells and were no longer cytotoxic. These data indicate that soluble, fibrillar Aß oligomers bind to PrP(C) in a conformation-dependent manner and require the integrity of lipid rafts and the transmembrane LRP1 for their cytotoxicity, thus revealing potential targets to alleviate the neurotoxic properties of Aß oligomers in AD.

Prion protein facilitates uptake of zinc into neuronal cells.

Zinc is released into the synaptic cleft upon exocytotic stimuli, although the mechanism for its reuptake into neurons is unresolved. Here we show that the cellular prion protein enhances the uptake of zinc into neuronal cells. This prion-protein-mediated zinc influx requires the octapeptide repeats and amino-terminal polybasic region in the prion protein, but not its endocytosis. Selective antagonists of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptors block the prion protein-mediated zinc uptake, and the prion protein co-immunoprecipitates with both GluA1 and GluA2 AMPA receptor subunits. Zinc-sensitive intracellular tyrosine phosphatase activity is decreased in cells expressing prion protein and increased in the brains of prion-protein-null mice, providing evidence of a physiological consequence of this process. Prion protein-mediated zinc uptake is ablated in cells expressing familial associated mutants of the protein and in prion-infected cells. These data suggest that alterations in the cellular prion protein-mediated zinc uptake may contribute to neurodegeneration in prion and other neurodegenerative diseases.

Lipid Rafts: Linking Alzheimer's Amyloid-ß Production, Aggregation, and Toxicity at Neuronal Membranes.

Lipid rafts are membrane microdomains, enriched in cholesterol and sphingolipids, into which specific subsets of proteins and lipids partition, creating cell-signalling platforms that are vital for neuronal functions. Lipid rafts play at least three crucial roles in Alzheimer's Disease (AD), namely, in promoting the generation of the amyloid-ß (Aß) peptide, facilitating its aggregation upon neuronal membranes to form toxic oligomers and hosting specific neuronal receptors through which the AD-related neurotoxicity and memory impairments of the Aß oligomers are transduced. Recent evidence suggests that Aß oligomers may exert their deleterious effects through binding to, and causing the aberrant clustering of, lipid raft proteins including the cellular prion protein and glutamate receptors. The formation of these pathogenic lipid raft-based platforms may be critical for the toxic signalling mechanisms that underlie synaptic dysfunction and neuropathology in AD.