Fibroblast Attachment Sites on Tropoelastin

Tropoelastin is the dominant monomer that assembles to form elastin, which confers elasticity to vertebrate elastic tissues including skin, arteries and lungs. This thesis explores regions in tropoelastin that are involved in cell binding. Cell interactions with tropoelastin were probed by utilising a total of 15 recombinant tropoelastin constructs, which contain different domains of tropoelastin. Through sequential analyses of these constructs’ ability to interact with cells, multiple regions of cell interaction were identified. One of these cell interactive sequences in tropoelastin was mapped to domain 17 and the first 6 amino acids (aa) of domain 18. A peptide made to this region promoted cell attachment and spreading independently. Inhibition studies involving heparan sulfate, EDTA and anti-integrin antibodies revealed a possible two-step mechanism by which cell interactions occur at this region: initially, cell adhesion is mediated by glycosaminoglycans (GAGs), which contact the lysine residues within the target sequence, and subsequently facilitate cell spreading modulated by integrins, specifically αvβ3 and αvβ5. Further studies confirmed integrin-mediated binding site/s in domains 12-16, independent from domains 17-18. Domain 12-16 was found to interact through both the integrin αv family and integrin α5β1, whereas integrin α5β1 only inhibited in combination with integrin αv. On this basis a model was developed where the αv integrins initially engage with tropoelastin, which then allows for integrin α5β1 engagement, further strengthening the tropoelastin-cell interaction. This work identifies for the first time multiple sites in tropoelastin in the central region of tropoelastin. Discovering novel cell adhesion sequences and understanding the mechanisms involved in the interaction would substantially contribute to the next generation of biomaterials and provide a platform for future studies to understand biochemical pathways in the matrix biology field

Opposing effects of TIGAR- and RAC1-derived ROS on Wnt-driven proliferation in the mouse intestine

Reactive oxygen species (ROS) participate in numerous cell responses, including proliferation, DNA damage, and cell death. Based on these disparate activities, both promotion and inhibition of ROS have been proposed for cancer therapy. However, how the ROS response is determined is not clear. We examined the activities of ROS in a model of Apc deletion, where loss of the Wnt target gene Myc both rescues APC loss and prevents ROS accumulation. Following APC loss, Myc has been shown to up-regulate RAC1 to promote proliferative ROS through NADPH oxidase (NOX). However, APC loss also increased the expression of TIGAR, which functions to limit ROS. To explore this paradox, we used three-dimensional (3D) cultures and in vivo models to show that deletion of TIGAR increased ROS damage and inhibited proliferation. These responses were suppressed by limiting damaging ROS but enhanced by lowering proproliferative NOX-derived ROS. Despite having opposing effects on ROS levels, loss of TIGAR and RAC1 cooperated to suppress intestinal proliferation following APC loss. Our results indicate that the pro- and anti-proliferative effects of ROS can be independently modulated in the same cell, with two key targets in the Wnt pathway functioning to integrate the different ROS signals for optimal cell proliferation

VIDA: a virus database system for the organization of animal virus genome open reading frames

VIDA is a new virus database that organizes open reading frames (ORFs) from partial and complete genomic sequences from animal viruses. Currently VIDA includes all sequences from GenBank for Herpesviridae, Coronaviridae and Arteriviridae. The ORFs are organized into homologous protein families, which are identified on the basis of sequence similarity relationships, Conserved sequence regions of potential functional importance are identified and can be retrieved as sequence alignments. We use a controlled taxonomical and functional classification for all the proteins and protein families in the database. When available, protein structures that are related to the families have also been included. The database is available for online search and sequence information retrieval at http://www.biochem.ucl.ac.uk/bsm/virus-database/ VIDA.html

Trends and Associated Factors of Use of Opioid, Heroin, and Cannabis Among Patients for Emergency Department Visits in Nevada: 2009–2017

To examine trends and contributing factors of opioid, heroin, and cannabis-associated emergency department (ED) visits in Nevada. The 2009 to 2017 Nevada State ED database (n = 7,950,554 ED visits) were used. Use of opioid, heroin, and cannabis, respectively, was identified by the International Classification of Diseases, 9th & 10th Revisions. Three multivariable models, one for each of the 3 dependent variables, were conducted. Independent variables included year, insurance status, race/ethnicity, use of other substance, and mental health conditions. The number of individuals with opioid, heroin, cannabis-associated ED visits increased 3%, 10%, and 23% annually from 2009 to 2015, particularly among 21 to 29 age group, females, and African Americans. Use of other substance (odds ratio [OR] = 3.91; 95% confidence interval [CI] = 3.84, 3.99; reference - no use of other substance), mental health conditions (OR = 2.48; 95% CI = 2.43, 2.53; reference – without mental health conditions), Medicaid (OR = 1.41; 95% CI = 1.38, 1.44; reference – non-Medicaid), Medicare (OR = 1.44; 95% CI = 1.39, 1.49; reference – non-Medicare) and uninsured patients (OR = 1.52; 95% CI = 1.49, 1.56; reference - insured) were predictors of all three substance-associated ED visits. With a steady increase in trends of opioid, heroin, and cannabis-associated ED visits in recent years, the main contributing factors include patient sociodemographic factors, mental health conditions, and use of other substances

Uptake of Virtual Visits in A Geriatric Primary Care Clinic During the COVID‐19 Pandemic

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/156159/2/jgs16534.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156159/1/jgs16534_am.pd

Phylogenetic Rate Shifts in Feeding Time During the Evolution of Homo

Unique among animals, humans eat a diet rich in cooked and nonthermally processed food. The ancestors of modern humans who invented food processing (including cooking) gained critical advantages in survival and fitness through increased caloric intake. However, the time and manner in which food processing became biologically significant are uncertain. Here, we assess the inferred evolutionary consequences of food processing in the human lineage by applying a Bayesian phylogenetic outlier test to a comparative dataset of feeding time in humans and nonhuman primates. We find that modern humans spend an order of magnitude less time feeding than predicted by phylogeny and body mass (4.7% vs. predicted 48% of daily activity). This result suggests that a substantial evolutionary rate change in feeding time occurred along the human branch after the human–chimpanzee split. Along this same branch, Homo erectus shows a marked reduction in molar size that is followed by a gradual, although erratic, decline in H. sapiens. We show that reduction in molar size in early Homo (H. habilis and H. rudolfensis) is explicable by phylogeny and body size alone. By contrast, the change in molar size to H. erectus, H. neanderthalensis, and H. sapiens cannot be explained by the rate of craniodental and body size evolution. Together, our results indicate that the behaviorally driven adaptations of food processing (reduced feeding time and molar size) originated after the evolution of Homo but before or concurrent with the evolution of H. erectus, which was around 1.9 Mya.Human Evolutionary BiologyOrganismic and Evolutionary Biolog

The in vivo function of TIGAR, a p53 target gene that regulates glucose metabolism

The p53 tumour suppressor inhibits tumour development via various mechanisms such as apoptosis, inhibition of proliferation or the activation of senescence. Recently, several studies have indicated a novel role of p53 in the regulation of energy metabolism. Previously we have discovered TIGAR, a p53 target gene that acts as a fructose-2,6-bisphosphatase. TIGAR would therefore be predicted to redirect glucose from the glycolytic pathway to secondary pathways such as the pentose phosphate pathway (PPP). Indeed, TIGAR can promote NADPH production to generate reduced glutathione for protection against ROS. In order to understand the function of TIGAR in vivo, we generated TIGAR deficient mice. We have determined a critical role of TIGAR in rapidly proliferating tissue, either for repair after damage or during tumor development. These studies support a role for TIGAR in maintaining both antioxidant activity and nucleotide synthesis, both generated through the PPP. We are now also investigating the role of TIGAR in other metabolic pathways such as the hexosamine biosynthesis pathway, and in other animal models of cancer

Development of an inducible mouse model of iRFP713 to track recombinase activity and tumour development in vivo

While the use of bioluminescent proteins for molecular imaging is a powerful technology to further our understanding of complex processes, fluorescent labeling with visible light fluorescent proteins such as GFP and RFP suffers from poor tissue penetration and high background autofluorescence. To overcome these limitations, we generated an inducible knock-in mouse model of iRFP713. This model was used to assess Cre activity in a Rosa Cre-ER background and quantify Cre activity upon different tamoxifen treatments in several organs. We also show that iRFP can be readily detected in 3D organoid cultures, FACS analysis and in vivo tumour models. Taken together we demonstrate that iRFP713 is a progressive step in in vivo imaging and analysis that widens the optical imaging window to the near-infrared spectrum, thereby allowing deeper tissue penetration, quicker image acquisition without the need to inject substrates and a better signal to background ratio in genetically engineered mouse models (GEMMs)