201 research outputs found
The generalized second law for the interacting generalized Chaplygin gas model
We investigate the validity of the generalized second law (GSL) of
gravitational thermodynamics in a non-flat FRW universe containing the
interacting generalized Chaplygin gas with the baryonic matter. The dynamical
apparent horizon is assumed to be the boundary of the universe. We show that
for the interacting generalized Chaplygin gas as a unified candidate for dark
matter (DM) and dark energy (DE), the equation of state parameter can cross the
phantom divide. We also present that for the selected model under thermal
equilibrium with the Hawking radiation, the GSL is always satisfied throughout
the history of the universe for any spatial curvature, independently of the
equation of state of the interacting generalized Chaplygin gas model.Comment: 8 page
Advanced Technologies for Oral Controlled Release: Cyclodextrins for oral controlled release
Cyclodextrins (CDs) are used in oral pharmaceutical formulations, by means of inclusion complexes formation, with the following advantages for the drugs: (1) solubility, dissolution rate, stability and bioavailability enhancement; (2) to modify the drug release site and/or time profile; and (3) to reduce or prevent gastrointestinal side effects and unpleasant smell or taste, to prevent drug-drug or drug-additive interactions, or even to convert oil and liquid drugs into microcrystalline or amorphous powders. A more recent trend focuses on the use of CDs as nanocarriers, a strategy that aims to design versatile delivery systems that can encapsulate drugs with better physicochemical properties for oral delivery. Thus, the aim of this work was to review the applications of the CDs and their hydrophilic derivatives on the solubility enhancement of poorly water soluble drugs in order to increase their dissolution rate and get immediate release, as well as their ability to control (to prolong or to delay) the release of drugs from solid dosage forms, either as complexes with the hydrophilic (e.g. as osmotic pumps) and/ or hydrophobic CDs. New controlled delivery systems based on nanotechonology carriers (nanoparticles and conjugates) have also been reviewed
Phenotype instability of hepatocyte-like cells produced by direct reprogramming of mesenchymal stromal cells
Submitted by Ana Maria Fiscina Sampaio ([email protected]) on 2020-05-20T13:36:52Z
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Previous issue date: 2020Fundação de Amparo à Pesquisa do Estado da Bahia (FAPESB), Conselho
Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação Oswaldo Cruz. Instituto Gonçalo Moniz. Salvador, BA, Brasil / São Rafael Hospital. Center for Biotechnology and Cell Therapy, Salvador, BA, Brazil.MRC Centre for Regenerative Medicine. Edinburgh, UK.Fundação Oswaldo Cruz. Instituto Gonçalo Moniz. Salvador, BA, Brasil / São Rafael Hospital. Center for Biotechnology and Cell Therapy, Salvador, BA, Brazil.Fundação Oswaldo Cruz. Instituto Gonçalo Moniz. Salvador, BA, Brasil / São Rafael Hospital. Center for Biotechnology and Cell Therapy, Salvador, BA, Brazil / D’Or Institute for Research and Education. Rio de Janeiro, RJ, Brazil.Universidade Federal da Bahia. Institute of Health Sciences. Salvador, BA, Brasil.MRC Centre for Regenerative Medicine. Edinburgh, UK.São Rafael Hospital. Center for Biotechnology and Cell Therapy, Salvador, BA, Brazil / D’Or Institute for Research and Education. Rio de Janeiro, RJ, Brazil.São Rafael Hospital. Center for Biotechnology and Cell Therapy, Salvador, BA, Brazil / D’Or Institute for Research and Education. Rio de Janeiro, RJ, Brazil.Fundação Oswaldo Cruz. Instituto Gonçalo Moniz. Salvador, BA, Brasil / National Institute of Science and Technology for Regenerative Medicine. Rio de Janeiro, RJ, Brazil.Fundação Oswaldo Cruz. Instituto Gonçalo Moniz. Salvador, BA, Brasil.Fundação Oswaldo Cruz. Instituto Gonçalo Moniz. Salvador, BA, Brasil / São Rafael Hospital. Center for Biotechnology and Cell Therapy, Salvador, BA, Brazil.MRC Centre for Regenerative Medicine. Edinburgh, UK.Fundação Oswaldo Cruz. Instituto Gonçalo Moniz. Salvador, BA, Brasil / National Institute of Science and Technology for Regenerative Medicine. Rio de Janeiro, RJ, Brazil.Fundação Oswaldo Cruz. Instituto Gonçalo Moniz. Salvador, BA, Brasil / São Rafael Hospital. Center for Biotechnology and Cell Therapy, Salvador, BA, Brazil / D’Or Institute for Research and Education. Rio de Janeiro, RJ, Brazil / National Institute of Science and Technology for Regenerative Medicine. Rio de Janeiro, RJ, Brazil /Hepatocyte-like cells (iHEPs) generated by transcription factor-mediated direct reprogramming of somatic cells have been studied as potential cell sources for the development of novel therapies targeting liver diseases. The mechanisms involved in direct reprogramming, stability after long-term in vitro expansion, and safety profile of reprogrammed cells in different experimental models, however, still require further investigation. Methods: iHEPs were generated by forced expression of Foxa2/Hnf4a in mouse mesenchymal stromal cells and
characterized their phenotype stability by in vitro and in vivo analyses.
Results: The iHEPs expressed mixed hepatocyte and liver progenitor cell markers, were highly proliferative, and
presented metabolic activities in functional assays. A progressive loss of hepatic phenotype, however, was observed
after several passages, leading to an increase in alpha-SMA+ fibroblast-like cells, which could be distinguished and
sorted from iHEPs by differential mitochondrial content. The resulting purified iHEPs proliferated, maintained liver
progenitor cell markers, and, upon stimulation with lineage maturation media, increased expression of either biliary
or hepatocyte markers. In vivo functionality was assessed in independent pre-clinical mouse models. Minimal
engraftment was observed following transplantation in mice with acute acetaminophen-induced liver injury. In
contrast, upon transplantation in a transgenic mouse model presenting host hepatocyte senescence, widespread
engraftment and uncontrolled proliferation of iHEPs was observed, forming islands of epithelial-like cells, adipocytelike
cells, or cells presenting both morphologies.
Conclusion: The results have significant implications for cell reprogramming, suggesting that iHEPs generated by
Foxa2/Hnf4a expression have an unstable phenotype and depend on transgene expression for maintenance of
hepatocyte-like characteristics, showing a tendency to return to the mesenchymal phenotype of origin and a
compromised safety profil
Notes on interacting holographic dark energy model in a closed universe
We consider interacting holographic dark energy model in Friedmann Robertson
Walker space time with positive spatial curvature and investigate the behavior
of curvature parameter and dark energy density in accelerated expanding epoch.
We also derive some conditions needed to cross the phantom divide line in this
model.Comment: 10 pages, typos corrected, some explanations and references added and
updated, accepted for publication in JCA
Molecular Dynamics Analysis of Apolipoprotein-D - Lipid Hydroperoxide Interactions: Mechanism for Selective Oxidation of Met-93
Background: Recent studies suggest reduction of radical-propagating fatty acid hydroperoxides to inert hydroxides by interaction with apolipoprotein-D (apoD) Met93 may represent an antioxidant function for apoD. The nature and structural consequences of this selective interaction are unknown.
Methodology/Principal Findings: Herein we used molecular dynamics (MD) analysis to address these issues. Longtimescale simulations of apoD suggest lipid molecules are bound flexibly, with the molecules free to explore multiple conformations in a binding site at the entrance to the classical lipocalin ligand-binding pocket. Models of 5s- 12s- and 15s hydroperoxyeicosatetraenoic acids were created and the lipids found to wrap around Met93 thus providing a plausible mechanism by which eicosatetraenoic acids bearing hydroperoxides on different carbon atoms can interact with Met93 to yield Met93 sulfoxide (Met93SO). Simulations of glycosylated apoD indicated that a second solvent exposed Met at position 49 was shielded by a triantennerary N-glycan attached to Asn45 thereby precluding lipid interactions. MD simulations of apoD showed B-factors of the loop containing Met93SO were higher in the oxidized protein, indicating increased flexibility that is predicted to destabilize the protein and promote self-association.
Conclusions/Significance: These studies provide novel insights into the mechanisms that may contribute to the antioxidant function of apoD and the structural consequences that result if Met93SO is not redox-cycled back to its native state
MUC1 Limits Helicobacter pylori Infection both by Steric Hindrance and by Acting as a Releasable Decoy
The bacterium Helicobacter pylori can cause peptic ulcer disease, gastric adenocarcinoma and MALT lymphoma. The cell-surface mucin MUC1 is a large glycoprotein which is highly expressed on the mucosal surface and limits the density of H. pylori in a murine infection model. We now demonstrate that by using the BabA and SabA adhesins, H. pylori bind MUC1 isolated from human gastric cells and MUC1 shed into gastric juice. Both H. pylori carrying these adhesins, and beads coated with MUC1 antibodies, induced shedding of MUC1 from MKN7 human gastric epithelial cells, and shed MUC1 was found bound to H. pylori. Shedding of MUC1 from non-infected cells was not mediated by the known MUC1 sheddases ADAM17 and MMP-14. However, knockdown of MMP-14 partially affected MUC1 release early in infection, whereas ADAM17 had no effect. Thus, it is likely that shedding is mediated both by proteases and by disassociation of the non-covalent interaction between the α- and β-subunits. H. pylori bound more readily to MUC1 depleted cells even when the bacteria lacked the BabA and SabA adhesins, showing that MUC1 inhibits attachment even when bacteria cannot bind to the mucin. Bacteria lacking both the BabA and SabA adhesins caused less apoptosis in MKN7 cells than wild-type bacteria, having a greater effect than deletion of the CagA pathogenicity gene. Deficiency of MUC1/Muc1 resulted in increased epithelial cell apoptosis, both in MKN7 cells in vitro, and in H. pylori infected mice. Thus, MUC1 protects the epithelium from non-MUC1 binding bacteria by inhibiting adhesion to the cell surface by steric hindrance, and from MUC1-binding bacteria by acting as a releasable decoy
Identification of New SRF Binding Sites in Genes Modulated by SRF Over-Expression in Mouse Hearts
Background To identify in vivo new cardiac binding sites of serum response factor (SRF) in genes and to study the response of these genes to mild over-expression of SRF, we employed a cardiac-specific, transgenic mouse model, with mild over-expression of SRF (Mild-O SRF Tg). Methodology Microarray experiments were performed on hearts of Mild-O-SRF Tg at 6 months of age. We identified 207 genes that are important for cardiac function that were differentially expressed in vivo. Among them the promoter region of 192 genes had SRF binding motifs, the classic CArG or CArG-like (CArG-L) elements. Fifty-one of the 56 genes with classic SRF binding sites had not been previously reported. These SRF-modulated genes were grouped into 12 categories based on their function. It was observed that genes associated with cardiac energy metabolism shifted toward that of carbohydrate metabolism and away from that of fatty acid metabolism. The expression of genes that are involved in transcription and ion regulation were decreased, but expression of cytoskeletal genes was significantly increased. Using public databases of mouse models of hemodynamic stress (GEO database), we also found that similar altered expression of the SRF-modulated genes occurred in these hearts with cardiac ischemia or aortic constriction as well. Conclusion and significance SRF-modulated genes are actively regulated under various physiological and pathological conditions. We have discovered that a large number of cardiac genes have classic SRF binding sites and were significantly modulated in the Mild-O-SRF Tg mouse hearts. Hence, the mild elevation of SRF protein in the heart that is observed during typical adult aging may have a major impact on many SRF-modulated genes, thereby affecting Cardiac structure and performance. The results from our study could help to enhance our understanding of SRF regulation of cellular processes in the aged heart
Tracking Membrane Protein Association in Model Membranes
Membrane proteins are essential in the exchange processes of cells. In spite of great breakthrough in soluble proteins studies, membrane proteins structures, functions and interactions are still a challenge because of the difficulties related to their hydrophobic properties. Most of the experiments are performed with detergent-solubilized membrane proteins. However widely used micellar systems are far from the biological two-dimensions membrane. The development of new biomimetic membrane systems is fundamental to tackle this issue
Global patient outcomes after elective surgery: prospective cohort study in 27 low-, middle- and high-income countries.
BACKGROUND: As global initiatives increase patient access to surgical treatments, there remains a need to understand the adverse effects of surgery and define appropriate levels of perioperative care. METHODS: We designed a prospective international 7-day cohort study of outcomes following elective adult inpatient surgery in 27 countries. The primary outcome was in-hospital complications. Secondary outcomes were death following a complication (failure to rescue) and death in hospital. Process measures were admission to critical care immediately after surgery or to treat a complication and duration of hospital stay. A single definition of critical care was used for all countries. RESULTS: A total of 474 hospitals in 19 high-, 7 middle- and 1 low-income country were included in the primary analysis. Data included 44 814 patients with a median hospital stay of 4 (range 2-7) days. A total of 7508 patients (16.8%) developed one or more postoperative complication and 207 died (0.5%). The overall mortality among patients who developed complications was 2.8%. Mortality following complications ranged from 2.4% for pulmonary embolism to 43.9% for cardiac arrest. A total of 4360 (9.7%) patients were admitted to a critical care unit as routine immediately after surgery, of whom 2198 (50.4%) developed a complication, with 105 (2.4%) deaths. A total of 1233 patients (16.4%) were admitted to a critical care unit to treat complications, with 119 (9.7%) deaths. Despite lower baseline risk, outcomes were similar in low- and middle-income compared with high-income countries. CONCLUSIONS: Poor patient outcomes are common after inpatient surgery. Global initiatives to increase access to surgical treatments should also address the need for safe perioperative care. STUDY REGISTRATION: ISRCTN5181700
Multi-messenger observations of a binary neutron star merger
On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta
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