Interview with Bruce and Lisa Rickard

Bruce and Lisa Rickard talk about their farm.https://digital.kenyon.edu/elfs_interviews/1053/thumbnail.jp

In vitro characterization of nanodrugs at model lipid membranes

The use of nano-sized drug carriers to improve the efficiency of drug delivery has become well established during the past decades. New nanoparticle (NP) formulations for the administration of biopharmaceuticals (e.g. proteins and peptides) emerge at an increasing rate and the need for methods to evaluate their properties is expanding. Rational design of drug carriers requires understanding of their biophysical interactions with various biological barriers, e.g. cell membranes, mucus layers, or the blood brain barrier, since most carriers aim to deliver drugs across one or more of such barriers. The shape of NPs and the way they adhere to the cell membrane are important determinants for triggering of endocytosis. Another important NP parameter is their responsiveness to changes in the ambient environment when entering intracellular compartments e.g. the endosome or the cytosol. In this thesis, an in vitro screening platform for studying of NP – lipid membrane interaction is presented and used to characterize insulin-loaded polymeric NPs with respect to their interaction with differently charged supported lipid bilayers. By combining different surface sensitive techniques (quartz crystal microbalance with dissipation monitoring, reflectometry, and atomic force microscopy), structural properties of nano-sized polyelectrolyte complexes upon adsorption to model membranes were studied. From the results it is clear that electrostatic forces are important for the outcome of the NP-lipid membrane adsorption process. Polyelectrolyte complexes, which are non covalent assemblies of oppositely charged polyions, adopted different shapes on different membranes. Upon strong electrostatic attraction between the NPs and the membrane, NPs collapsed into a thin layer on top of an oppositely charged model membrane. This rearrangement process is potentially unfavorable for uptake into epithelial cells through endocytosis. NPs based on polymers with disulfide linkages in the polymer backbone were responsive to reducing agents. This property was shown by exposing membrane-adsorbed bioreducible poly(amido amine) based polyelectrolyte complexes to glutathione, mimicking an intracellular reductive environment. Similarly, the responsiveness of the NPs towards a decrease in ambient pH, mimicking the low pH in the late endosome, was shown. These results show the application of an experimental platform based on engineered supported lipid membranes and surface sensitive analytical techniques to evaluate drug carriers with respect to their membrane interactions as well as their responsiveness. The information gained from screening of novel drug carries gives important guidance during the process of design and development. An important next step in the development of the presented platform will be to establish a correlation to in vitro cell culture assays. NPs for other purposes could also be evaluated

Probing the Nano-Bio Interface Using Surface Based Analytical Techniques

In recent years, the use of manufactured nanomaterials has been rapidly increasing in a wide range of application areas. Among others, these areas of application include cosmetics, medicine, clothing, and sporting goods. The small size of nanomaterials offers unique properties that are not possible to obtain by the same material in bulk. Although the use of nanomaterials holds great promises for society, the increased use and production also increases the concern that engineered nanomaterials may have adverse effects on human health or the environment. Unlike chemical substances, which have a defined structure and mass, nanomaterials need to be described by a large number of descriptors, e.g., size distribution, shape, and composition. In addition, to address possible effects on humans or the environment, it is of great importance to determine how nanomaterials interact with biological matter. Interactions with proteins, cell membranes, and cells may cause protein coronas, cellular uptake, or biocatalytic processes. To fully characterize such interactions there is a strong need for novel analytical techniques or methodologies. In this thesis, I have investigated how the lipid membrane, one of the most vital structures of a cell, interacts with various types of nanomaterials (e.g. polyelectrolyte complexes, graphene oxide, and TiO2 nanoparticles). The interactions between the model membranes and the nanomaterials have been studied using several complementary surface sensitive techniques. The results have showed conformational changes of polyelectrolyte complexes upon adsorption to the membranes and triggered disintegration of such complexes upon exposure to an acidic or a reducing environment. Furthermore, TiO2 nanoparticles have been shown to be able to disrupt lipid membranes in a Ca2+-mediated mechanism and a novel nanocomposite material, composed of alternating layers of graphene oxide and lipid membranes, has been prepared. In addition, the quartz-crystal microbalance with dissipation monitoring technique (QCM-D) has been explored in studies of intracellular transport processes using living cells. Specifically, pigment translocation in Xenopus laevis melanophores, has been shown to generate significant QCM-D responses. By using the described methodology, it is possible to evaluate the nanoparticle design and study how nanomaterials behave at a biological interface or effect specific cellular functions

The burden of peripheral intravenous catheters in older hospital inpatients : a national cross-sectional study part of the One Million Global Peripheral Intravenous Catheters Collaboration

Objectives: To investigate the burden of peripheral intravenous catheters (PIVCs) in older hospitalised patients. Methods: A cross-sectional prospective observational study (2014/2015) to describe the characteristics, indications and outcomes of PIVCs among patients aged ≥65 from 65 Australian hospitals. Results: Amongst 2179 individual PIVCs (in 2041 patients, mean age 77.6 years, 45% female, 58% in NSW), 43% were inserted by doctors and 74% used that day, meaning 25% were ‘idle’. Overall, 18% (393/2179) exhibited signs of PIVC-related complications. Most commonly exhibited PIVC-related complications were tenderness (4.1%) and local redness (1.8%). Nearly one in three (29.1%) dressings was soiled, loosened or had come off, and only 36.8% had the time and date documented on the dressing. Both infusing IV medications (aOR 1.74, 95% CI 1.28–2.38, p 84 years) was independently associated with lower likelihood of a high score (aOR 0.71, 95% CI 0.54–0.94, p = 0.02). Conclusions: Given 1 in 5 PIVCs were identified with having complications, further research should focus on optimising PIVC use in older patients

Use of short peripheral intravenous catheters: characteristics, management, and outcomes worldwide

BACKGROUND: Peripheral intravenous catheter (PIVC) use in health care is common worldwide. Failure of PIVCs is also common, resulting in premature removal and replacement. OBJECTIVE: To investigate the characteristics, management practices, and outcomes of PIVCs internationally. DESIGN: Cross-sectional study. SETTING/PATIENTS: Hospitalized patients from rural, regional, and metropolitan areas internationally. MEASUREMENTS: Hospital, device, and inserter characteristics were collected along with assessment of the catheter insertion site. PIVC use in different geographic regions was compared. RESULTS: We reviewed 40,620 PIVCs in 51 countries. PIVCs were used primarily for intravenous medication (n = 28,571, 70%) and predominantly inserted in general wards (n = 22,167, 55%). Two-thirds of all devices were placed in non-recommended sites such as the hand, wrist, or antecubital veins. Nurses inserted most PIVCs (n = 28,575, 71%); although there was wide regional variation (26% to 97%). The prevalence of idle PIVCs was 14% (n = 5,796). Overall, 10% (n = 4,204) of PIVCs were painful to the patient or otherwise symptomatic of phlebitis; a further 10% (n = 3,879) had signs of PIVC malfunction; and 21% of PIVC dressings were suboptimal (n = 8,507). Over one-third of PIVCs (n = 14,787, 36%) had no documented daily site assessment and half (n = 19,768, 49%) had no documented date and time of insertion. CONCLUSIONS: In this study, we found that many PIVCs were placed in areas of "exion, were symptomatic or idle, had suboptimal dressings, or lacked adequate documentation. This suggests inconsistency between recommended management guidelines for PIVCs and current practice

A Method to Quantify Molecular Diffusion within Thin Solvated Polymer Films: A Case Study on Films of Natively Unfolded Nucleoporins

We present a method to probe molecular and nanoparticle diffusion within thin, solvated polymer coatings. The device exploits the confinement with well-defined geometry that forms at the interface between a planar and a hemispherical surface (of which at least one is coated with polymers) in close contact and uses this confinement to analyze diffusion processes without interference of exchange with and diffusion in the bulk solution. With this method, which we call plane–sphere confinement microscopy (PSCM), information regarding the partitioning of molecules between the polymer coating and the bulk liquid is also obtained. Thanks to the shape of the confined geometry, diffusion and partitioning can be mapped as a function of compression and concentration of the coating in a single experiment. The method is versatile and can be integrated with conventional optical microscopes; thus it should find widespread use in the many application areas exploiting functional polymer coatings. We demonstrate the use of PSCM using brushes of natively unfolded nucleoporin domains rich in phenylalanine–glycine repeats (FG domains). A meshwork of FG domains is known to be responsible for the selective transport of nuclear transport receptors (NTRs) and their macromolecular cargos across the nuclear envelope that separates the cytosol and the nucleus of living cells. We find that the selectivity of NTR uptake by FG domain films depends sensitively on FG domain concentration and that the interaction of NTRs with FG domains obstructs NTR movement only moderately. These observations contribute important information to better understand the mechanisms of selective NTR transport

Paired helical filament-forming region of tau (297–391) influences endogenous tau protein and accumulates in acidic compartments in human neuronal cells

Assembly of tau protein into paired helical filaments and straight filaments is a key feature of Alzheimer's disease. Aggregation of tau has been implicated in neurodegeneration, cellular toxicity and the propagation, which accompanies disease progression. We have reported previously that a region of tau (297–391), referred to as dGAE, assembles spontaneously in physiological conditions to form paired helical filament-like fibres in vitro in the absence of additives such as heparin. This provides a valuable tool with which to explore the effects of tau in cell culture. Here we have studied the cellular uptake of soluble oligomeric and fibrillar forms of dGAE and examined the downstream consequences of tau internalisation into differentiated SH-SY5Y neuroblastoma cells using fluorescence and electron microscopy alongside structural and biochemical analyses. The assembled dGAE shows more acute cytotoxicity than the soluble, non-aggregated form. Conversely, the soluble form is much more readily internalised and, once within the cell, is able to associate with endogenous tau resulting in increased phosphorylation and aggregation of endogenous tau, which accumulates in lysosomal/endosomal compartments. It appears that soluble oligomeric forms are able to propagate tau pathology without being acutely toxic. The model system we have developed now permits the molecular mechanisms of propagation of tau pathology to be studied in vitro in a more physiological manner with a view to development of novel therapeutic approaches

Prognostic model to predict postoperative acute kidney injury in patients undergoing major gastrointestinal surgery based on a national prospective observational cohort study.

Background: Acute illness, existing co-morbidities and surgical stress response can all contribute to postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery. The aim of this study was prospectively to develop a pragmatic prognostic model to stratify patients according to risk of developing AKI after major gastrointestinal surgery. Methods: This prospective multicentre cohort study included consecutive adults undergoing elective or emergency gastrointestinal resection, liver resection or stoma reversal in 2-week blocks over a continuous 3-month period. The primary outcome was the rate of AKI within 7 days of surgery. Bootstrap stability was used to select clinically plausible risk factors into the model. Internal model validation was carried out by bootstrap validation. Results: A total of 4544 patients were included across 173 centres in the UK and Ireland. The overall rate of AKI was 14·2 per cent (646 of 4544) and the 30-day mortality rate was 1·8 per cent (84 of 4544). Stage 1 AKI was significantly associated with 30-day mortality (unadjusted odds ratio 7·61, 95 per cent c.i. 4·49 to 12·90; P < 0·001), with increasing odds of death with each AKI stage. Six variables were selected for inclusion in the prognostic model: age, sex, ASA grade, preoperative estimated glomerular filtration rate, planned open surgery and preoperative use of either an angiotensin-converting enzyme inhibitor or an angiotensin receptor blocker. Internal validation demonstrated good model discrimination (c-statistic 0·65). Discussion: Following major gastrointestinal surgery, AKI occurred in one in seven patients. This preoperative prognostic model identified patients at high risk of postoperative AKI. Validation in an independent data set is required to ensure generalizability

Bone regeneration and stem cells.

?  Introduction ?  Bone fracture healing and healing problems ?  Biomaterial scaffolds and tissue engineering in bone formation -  Bone tissue engineering -  Biomaterial scaffolds -  Synthetic scaffolds -  Micro- and nanostructural properties of scaffolds -  Conclusion ?  Mesenchymal stem cells and osteogenesis -  Bone tissue -  Origin of osteoblasts -  Isolation and characterization of bone marrow derived MSC -  In vitro differentiation of MSC into osteoblast lineage cells -  In vivo differentiation of MSC into bone -  Factors and pathways controlling osteoblast differentiation of hMSC -  Defining the relationship between osteoblast and adipocyte differentiation from MSC -  MSC and sex hormones -  Effect of aging on osteoblastogenesis -  Conclusion ?  Embryonic, foetal and adult stem cells in osteogenesis -  Cell-based therapies for bone -  Specific features of bone cells needed to be advantageous for clinical use -  Development of therapeutic biological agents -  Clinical application concerns -  Conclusion ?  Platelet-rich plasma (PRP), growth factors and osteogenesis -  PRP effects in vitro on the cells involved in bone repair -  PRP effects on osteoblasts -  PRP effects on osteoclasts -  PRP effects on endothelial cells -  PRP effects in vivo on experimental animals -  The clinical use of PRP for bone repair -  Non-union -  Distraction osteogenesis -  Spinal fusion -  Foot and ankle surgery -  Total knee arthroplasty -  Odontostomatology and maxillofacial surgery -  Conclusion ?  Molecular control of osteogenesis -  TGF-β signalling -  FGF signalling -  IGF signalling -  PDGF signalling -  MAPK signalling pathway -  Wnt signalling pathway -  Hedgehog signalling -  Notch signalling -  Ephrin signalling -  Transcription factors regulating osteoblast differentiation -  Conclusion ?  Summary This invited review covers research areas of central importance for orthopaedic and maxillofacial bone tissue repair, including normal fracture healing and healing problems, biomaterial scaffolds for tissue engineering, mesenchymal and foetal stem cells, effects of sex steroids on mesenchymal stem cells, use of platelet-rich plasma for tissue repair, osteogenesis and its molecular markers. A variety of cells in addition to stem cells, as well as advances in materials science to meet specific requirements for bone and soft tissue regeneration by addition of bioactive molecules, are discussed

Characterization of nanoparticle-lipid membrane interactions using QCM-D

In vitro characterization of nanoparticles is becoming increasingly important due to the rapid development of novel nanoparticle formulations for applications in the field of nanomedicine and related areas. Commonly, nanoparticles are simply characterized with respect to their size and zeta potential, and additional in vitro characterization of nanoparticles is needed to develop useful nanoparticle structure-activity relationships. In this context it is highly interesting to characterize the interactions between nanoparticles and model interfaces, such as lipid membranes. Here, we describe a methodology to study such interactions using the quartz crystal microbalance with dissipation monitoring technique (QCM-D). In order to mimic some aspects of the native cell membrane, a supported lipid membrane is formed on the QCM-D sensor surface. Subsequently the membrane is exposed to nanoparticles, and the nanoparticle-lipid membrane interactions are monitored in real time. The outcome of such analysis provides information on the adsorption process (importantly kinetics and adsorbed amounts) as well as on the integrity of both the nanoparticles and the lipid membrane upon interaction. QCM-D analyses are suitable for screening of nanoparticle-lipid membrane interactions due to the fair throughput of the technique, which can be complemented, when needed, by additional analyses by other surface-sensitive analytical techniques