Search

Excitotoxic events underlying ischaemic and traumatic brain injuries activate degenerative and protective pathways, particularly in the hippocampus. To understand opposing pathways that determine the brain's response to excitotoxicity, we used hippocampal explants, thereby eliminating systemic variables during a precise protocol of excitatory stimulation. N‐methyl‐d‐aspartate (NMDA) was applied for 20 min and total RNA isolated one and 24 h later for neurobiology‐specific microarrays. Distinct groups of genes exhibited early vs. delayed induction, with 63 genes exclusively reduced 24‐h post‐insult. Egr‐1 and NOR‐1 displayed biphasic transcriptional modulation: early induction followed by delayed suppression. Opposing events of NMDA‐induced genes linked to pathogenesis and cell survival constituted the early expression signature. Delayed degenerative indicators (up‐regulated pathogenic genes, down‐regulated pro‐survival genes) and opposing compensatory responses (down‐regulated pathogenic genes, up‐regulated pro‐survival genes) generated networks with temporal gene profiles mirroring coexpression network clustering. We then used the expression profiles to test whether NF‐κB, a potent transcription factor implicated in both degenerative and protective pathways, is involved in the opposing responses. The NF‐κB inhibitor MG‐132 indeed altered NMDA‐mediated transcriptional changes, revealing components of opposing expression signatures that converge on the single response element. Overall, this study identified counteracting avenues among the distinct responses to excitotoxicity, thereby suggesting multi‐target treatment strategies and implications for predictive medicine.

Mucociliary clearance is composed of three components (i.e., mucin secretion, airway surface hydration, and ciliary-activity) which function coordinately to clear inhaled microbes and other foreign particles from airway surfaces. Airway surface hydration is maintained by water fluxes driven predominantly by active chloride and sodium ion transport. The ion channels that mediate electrogenic ion transport are regulated by extracellular purinergic signals that signal through G protein-coupled receptors. These purinoreceptors and the signaling pathways they activate have been identified as possible therapeutic targets for treating lung disease. A systems-level description of airway surface liquid (ASL) homeostasis could accelerate development of such therapies. Accordingly, we developed a mathematical model to describe the dynamic coupling of ion and water transport to extracellular purinergic signaling. We trained our model from steady-state and time-dependent experimental measurements made using normal and cystic fibrosis (CF) cultured human airway epithelium. To reproduce CF conditions, reduced chloride secretion, increased potassium secretion, and increased sodium absorption were required. The model accurately predicted ASL height under basal normal and CF conditions and the collapse of surface hydration due to the accelerated nucleotide metabolism associated with CF exacerbations. Finally, the model predicted a therapeutic strategy to deliver nucleotide receptor agonists to effectively rehydrate the ASL of CF airways.

Active learning improves student performance in STEM courses. Exposure to active learning environments generally occurs through traditional laboratory courses and independent research, both of which require access to resources that are limited at many universities. A previously reported active learning-based undergraduate journal club improved student achievement in communicating science. Here, we expanded on this previous journal club to improve student performance in the process of science. We developed and implemented a series of workshops and seminars referred to as “CASL Club,” an undergraduate journal club targeted at improving student development in applying the scientific process. Students were surveyed before and after CASL club about their confidence in accessing, analyzing, and reporting scientific research. Post-CASL club, the students reported increases in confidence in their abilities to access and present scientific articles and write scientific abstracts. Additionally, the students reported improved confidence and performance in their courses. Compared to the previous journal club study, the majority of sampled journal club participants were not exposed to primary literature as part of their general coursework. Our results illustrate active-learning based undergraduate journal clubs as a way to expose students to primary literature and improve students’ ability to apply scientific process in an active-learning environment at resource-limited universities.

Active learning improves student performance in STEM courses. Exposure to active learning environments generally occurs through traditional laboratory courses and independent research, both of which require access to resources that are limited at many universities. A previously reported active learning-based undergraduate journal club improved student achievement in communicating science. Here, we expanded on this previous journal club to improve student performance in the process of science. We developed and implemented a series of workshops and seminars referred to as "CASL Club," an undergraduate journal club targeted at improving student development in applying the scientific process. Students were surveyed before and after CASL club about their confidence in accessing, analyzing, and reporting scientific research. Post-CASL club, the students reported increases in confidence in their abilities to access and present scientific articles and write scientific abstracts. Additionally, the students reported improved confidence and performance in their courses. Compared to the previous journal club study, the majority of sampled journal club participants were not exposed to primary literature as part of their general coursework. Our results illustrate active-learning based undergraduate journal clubs as a way to expose students to primary literature and improve students' ability to apply scientific process in an active-learning environment at resource-limited universities.

Systems biologists increasingly use network representations to investigate biochemical pathways and their dynamic behaviours. In this critical review, we discuss four commonly used network representations of chemical and biochemical pathways. We illustrate how some of these representations reduce network complexity but result in the ambiguous representation of biochemical pathways. We also examine the current theoretical approaches available to investigate the dynamic behaviour of chemical and biochemical networks. Finally, we describe how the critical chemical and biochemical pathways responsible for emergent dynamic behaviour can be identified using network mining and functional mapping approaches.

Conformational diseases result from the failure of a specific protein to fold into its correct functional state. The misfolded proteins can lead to the toxic aggregation of proteins. Protein misfolding in conformational diseases often displays a threshold behavior characterized by a sudden shift between nontoxic to toxic levels of misfolded proteins. In some conformational diseases, evidence suggests that misfolded proteins interact with bystander proteins (unfolded and native folded proteins), eliciting a misfolded phenotype. These bystander isomers would follow their normal physiological pathways in absence of misfolded proteins. In this article, we present a general mechanism of bystander and misfolded protein interaction which we have used to investigate how the threshold behavior in protein misfolding is triggered in conformational diseases. Using a continuous flow reactor model of the endoplasmic reticulum, we found that slight changes in the bystander protein residence time in the endoplasmic reticulum or the ratio of basal misfolded to bystander protein inflow rates can trigger the threshold behavior in protein misfolding. Our analysis reveals three mechanisms to rescue bystander proteins in conformational diseases. The results of our model can now help direct experiments to understand the threshold behavior and develop therapeutic strategies targeting the modulation of conformational diseases.

Interdisciplinary and collaborative projects involving large electronic data sets are commonplace and provide a challenge to record keeping efforts. Blogging software provides a tool to record experimental results and analysis as well as collaborate. Here, I discuss blogs and illustrate how one can be used in research record keeping. I think go on to discuss using blogs to interface with project team members and the public. Finally, I address data security and protection issues surrounding electronic data, which are important to any successful blogging for research record keeping and collaboration endeavor.

In the endoplasmic reticulum, protein production occurs through a complex set of reaction networks which synthesize and fold protein polypeptides. Proteins can misfold due to mutation or cellular stress. Accumulation of misfolded proteins can lead to the formation of toxic protein aggregates. Cells have evolved the unfolded protein response which removes misfolded proteins from the endoplasmic reticulum before aggregation can occur. Failure of protein synthesis and folding quality control is associated with disease. We are beginning to comprehend how these processes are controlled. Here, we develop two mathematical models to investigate how cellular quality control regulates protein homeostasis. Using parametric sensitivity analysis, we identify pathway parameters involved in increasing folded protein production.

Plasmodium falciparum, the protozoan that causes the most lethal form of human malaria, has been controlled principally by two safe, affordable drugs, chloroquine and sulfadoxine-pyrimethamine (SP). Studies in the laboratory and in the field have demonstrated that resistance to SP depends on non-synonymous point mutations in the dihydrofolate reductase (DHFR), and dihydropteroate synthase (DHPS) coding regions. Parasites that carry dhfr genes with 3 or 4 point mutations (51I/59R/108N triple mutation or 51I/59R/108N/164L quadruple mutation) are resistant to pyrimethamine in vitro and patients infected with these parasites respond poorly to SP treatment. The wide spread of these pyrimethamine-resistant alleles demonstrates the increased fitness over drug-sensitive alleles in the presence of the drug. However, it is not clear whether these alleles might reduce the fitness of parasites in the absence of drug pressure. As a first step, we compared the kinetic properties of the wild type, and three mutant alleles to determine whether the native DHFR-thymidylate synthase form of the mutant proteins showed compromised activity in vitro. The mutant enzymes had K(m) values for their substrate, dihydrofolate that were significantly lower than the wild type, k(cat) values in the same range as the wild type enzyme, and k(cat)/K(m) values higher than wild type. In contrast, the K(m) values for the NADPH cofactor were higher than wild type for the mutant enzymes. These observations suggest that the fitness of these parasites may not be compromised relative to those that carry the wild type allele, even without sustained SP drug pressure.