SciCombinator

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Concept: Release

212

The increasing burden of dengue, and the relative failure of traditional vector control programs highlight the need to develop new control methods. SIT using self-limiting genetic technology is one such promising method. A self-limiting strain of Aedes aegypti, OX513A, has already reached the stage of field evaluation. Sustained releases of OX513A Ae. aegypti males led to 80% suppression of a target wild Ae. aegypti population in the Cayman Islands in 2010. Here we describe sustained series of field releases of OX513A Ae. aegypti males in a suburb of Juazeiro, Bahia, Brazil. This study spanned over a year and reduced the local Ae. aegypti population by 95% (95% CI: 92.2%-97.5%) based on adult trap data and 81% (95% CI: 74.9-85.2%) based on ovitrap indices compared to the adjacent no-release control area. The mating competitiveness of the released males (0.031; 95% CI: 0.025-0.036) was similar to that estimated in the Cayman trials (0.059; 95% CI: 0.011 - 0.210), indicating that environmental and target-strain differences had little impact on the mating success of the OX513A males. We conclude that sustained release of OX513A males may be an effective and widely useful method for suppression of the key dengue vector Ae. aegypti. The observed level of suppression would likely be sufficient to prevent dengue epidemics in the locality tested and other areas with similar or lower transmission.

Concepts: Mosquito, Yellow fever, Aedes aegypti, Aedes, Dengue fever, Release, Cayman Islands, Grand Cayman

167

The LDL receptor (LDLR) supports efficient uptake of both LDL and VLDL remnants by binding lipoprotein at the cell surface, internalizing lipoprotein through coated pits and releasing lipoprotein in endocytic compartments before returning to the surface for further rounds of uptake. While many aspects of lipoprotein binding and receptor entry are well understood, it is less clear where, when and how the LDLR releases lipoprotein. To address these questions, the current study employed quantitative fluorescence imaging to visualize the uptake and endosomal processing of LDL and the VLDL remnant, β-VLDL. We find that lipoprotein release is rapid with most release occurring prior to entry of lipoprotein into early endosomes. Published biochemical studies have identified two mechanisms of lipoprotein release: one that involves the β-propeller module of the LDLR and a second that is independent of this module. Quantitative imaging comparing uptake supported by the normal LDLR or by an LDLR variant incapable of β-propeller-dependent release show that the β-propeller-independent process is sufficient for release for both lipoproteins, but that the β-propeller process accelerates both LDL and β-VLDL release. Together these findings define where, when and how lipoprotein release occurs and provide a generalizable methodology for visualizing endocytic handling in situ.

Concepts: Cholesterol, Low density lipoprotein receptor gene family, Lipoproteins, Endocytosis, Endosome, Release, LDL receptor

80

Biological substances based on proteins, including vaccines, antibodies, and enzymes, typically degrade at room temperature over time due to denaturation, as proteins unfold with loss of secondary and tertiary structure. Their storage and distribution therefore relies on a “cold chain” of continuous refrigeration; this is costly and not always effective, as any break in the chain leads to rapid loss of effectiveness and potency. Efforts have been made to make vaccines thermally stable using treatments including freeze-drying (lyophilisation), biomineralisation, and encapsulation in sugar glass and organic polymers. Here for the first time we show that proteins can be enclosed in a deposited silica “cage”, rendering them stable against denaturing thermal treatment and long-term ambient-temperature storage, and subsequently released into solution with their structure and function intact. This “ensilication” method produces a storable solid protein-loaded material without the need for desiccation or freeze-drying. Ensilication offers the prospect of a solution to the “cold chain” problem for biological materials, in particular for vaccines.

Concepts: DNA, Protein, Amino acid, Molecular biology, Temperature, Quaternary structure, Organic matter, Release

31

Open data is a vital pillar of open science and a key enabler for reproducibility, data reuse, and novel discoveries. Enforcement of open-data policies, however, largely relies on manual efforts, which invariably lag behind the increasingly automated generation of biological data. To address this problem, we developed a general approach to automatically identify datasets overdue for public release by applying text mining to identify dataset references in published articles and parse query results from repositories to determine if the datasets remain private. We demonstrate the effectiveness of this approach on 2 popular National Center for Biotechnology Information (NCBI) repositories: Gene Expression Omnibus (GEO) and Sequence Read Archive (SRA). Our Wide-Open system identified a large number of overdue datasets, which spurred administrators to respond directly by releasing 400 datasets in one week.

Concepts: DNA, Gene, Gene expression, Biology, Organism, Data, Data set, Release

28

For textiles containing nanosilver, we assessed benefit (antimicrobial efficacy) in parallel with potential to release nanosilver (impact) during multiple life cycle stages. The silver loading and method of silver attachment to the textile highly influenced the silver release during washing. Multiple sequential simulated household washing experiments for fabric swatches in DI water with or without detergent showed a range of silver release. The toxicity of washing experiment supernatants to zebrafish (Danio rerio) embryos was negligible, with the exception of the very highest Ag releases (~1 mg/L Ag). In fact, toxicity tests indicated that residual detergent exhibited greater adverse response than the released silver. While washing the fabrics did release silver, it did not affect their antimicrobial efficacy as demonstrated by >99.9% inhibition of E. coli growth on the textiles, even for textiles that retained as little as 2 µg/g Ag after washing. This suggests that very little nanosilver is required to control bacterial growth in textiles. Visible light irradiation of the fabrics reduced the extent of Ag release for textiles during subsequent washings. End-of-life experiments using simulated landfill conditions showed that silver remaining on the textile is likely to continue leaching from textiles after disposal in a landfill.

Concepts: Textile, Danio kyathit, Release

28

Bone morphogenetic proteins (BMPs) are the most potent osteoinductive growth factors. However, a delivery system is essential to take advantage of the osteoinductive effect of BMPs. The purpose of this study was to develop a sustained delivery system for recombinant human bone morphogenetic protein-2 (BMP-2). We covalently attached heparin to a cross-linked collagen type I coated tricalciumphosphate/hydroxyapatite (TCP/HA) bone substitute and subsequently loaded it with BMP-2. To systematically evaluate the contribution of each component with respect to the binding and release of BMP-2, six constructs were prepared and characterized: TCP/HA, TCP/HA with collagen (TCP/HACol), and TCP/HA with collagen and heparin (TCP/HAColHep) with and without BMP-2 (B). More BMP-2 bound to the TCP/HAColHep + B (92.9 ± 4.8 ng BMP-2/mg granule) granules as compared to the TCP/HACol + B (69.0 ± 9.6 ng BMP-2/mg granule) and TCP/HA + B granules (62.9 ± 5.4 ng BMP-2/mg granule). No difference in release pattern was found between the TCP/HA + B and TCP/HACol + B granules. Up to day 14, BMP-2 was still bound to the TCP/HAColHep + B granules, whereas most BMP had been released from TCP/HACol + B and TCP/HA + B granules at that time. After 21 days most BMP-2 also had been released from the TCP/HAColHep + B granules. The local and sustained delivery system for BMP-2 developed in this study may be useful as a carrier for BMP-2 and could possibly enhance bone regeneration efficacy for the treatment of large bone defects.

Concepts: Bone, Collagen, Developmental biology, Bone morphogenetic protein, Release, Type-I collagen, Bone morphogenetic protein 2, BMP-2

28

A new core-shell nanostructure consisting of inorganic hydroxyapatite (HAP) nanoparticles as the core and organic alginate as the shell (denoted as HAP@Alg) was successfully synthesized by a pre-gel method and applied to pH-responsive drug delivery systems (DDS). HAP@Alg nanoparticles have the advantages of hydroxyapatite and alginate, where hydroxyapatite provides pH-responsive degradability, and alginate provides excellent biocompatibility and COOH functionality. Through the subsequent addition of CaCl2 and phosphate solutions to the alginate solution, HAP@Alg nanoparticles with controllable particle sizes (ranging from 160 to 650 nm) were obtained, and their core-shell structure was confirmed through transmission electron microscopy (TEM) observation. Rhodamine 6G (R6G), a positively charged dye, was selected as a model drug for pH-sensitive DDS. R6G was encapsulated in the HAP/Alg nanoparticles upon synthesis, and its loading efficiency could reach up to approximately 63.0%. The in vitro release behavior of the loaded R6G at different pH values was systematically studied, and the results indicated that more R6G molecules were released at lower pH conditions. For example, after releasing for 8 h, the release amount of R6G at pH 2.0 was 2.53-fold the amount at pH 7.4. We attributed this pH-sensitive release behavior to the dissolution of the HAP core in acidic conditions. The results of the MTT assay and confocal laser scanning microscopy indicated that the HAP@Alg were successfully uptaken by liver cancer cells (HepG2) without apparent cytotoxicity. The synthesized HAP@Alg nanoparticles show great potential as drug nanovehicles with high biocompatibility, enhanced drug loading, and pH-responsive features for future intracellular DDS.

Concepts: Electron, Cancer, PH, Cytotoxicity, Transmission electron microscopy, MTT assay, Release, Rhodamine 6G

26

A combination therapy of metformin hydrochloride (MH) and repaglinide (RG) achieves a perfect glycemic control; however, the combination formulation of immediate release must be taken several times a day, compromising the therapeutic benefits and causing inconveniences to the patients. Herein, a bilayer matrix tablet that aimed at continuously releasing both MH and RG over time was developed, in which the two drugs were formulated into two separated layers. The tablets were prepared by wet granulation method, and the optimized formulation was obtained by evaluating the factors that affected the drug release. The bilayer tablets simultaneously released the two drugs over 12 h; and a better in vivo performance with a steady plasma concentration, markedly lower C max, prolonged T max, and perfect absorption was obtained. Summarily, the bilayer matrix tablets sustained both MH and RG release over time, thereby prolonging the actions for diabetic therapy and producing better health outcomes.

Concepts: Game theory, Pharmacology, Diabetes mellitus type 2, Insulin resistance, Sulfonylurea, Pharmaceutical formulation, Tablet, Release

25

Recent innovations in DNA nanofabrication allow the creation of intricately shaped nanostructures ideally suited for many biological applications. To advance the use of DNA nanotechnology for the controlled release of bioactive molecules, we report a general strategy that uses light to liberate encapsulated cargoes from DNA nanostructures with high spatiotemporal precision. Through the incorporation of a custom, photolabile cross-linker, we encapsulated cargoes ranging in size from small molecules to full-sized proteins within DNA nanocages and then released such cargoes upon brief exposure to light. This novel molecular uncaging technique offers a general approach for precisely releasing a large variety of bioactive molecules, allowing investigation into their mechanism of action, or finely tuned delivery with high temporal precision for broad biomedical and materials applications.

Concepts: DNA, Protein, Molecular biology, Molecule, Chemical substance, Nanotechnology, DNA nanotechnology, Release

25

On-demand release of bioactive substances with high spatial and temporal control offers ground-breaking possibilities in the field of life sciences. However, available strategies for developing such release systems lack the possibility of combining efficient control over release with adequate storage capability in a reasonably compact system. In this study we present a new approach to target this deficiency by the introduction of a hybrid material. This organic-inorganic material was fabricated by atomic layer deposition of ZnO into thin films of polyethylene glycol, forming the carrier matrix for the substance to be released. Sub-surface growth mechanisms during this process converted the liquid polymer into a solid, yet water-soluble, phase. This layer permits extended storage for various substances within a single film of only a few micrometers in thickness, and hence demands minimal space and complexity. Improved control over release of the model substance Fluorescein was achieved by coating the hybrid material with a conducting polymer film. Single dosage and repetitive dispensing from this system was demonstrated. Release was controlled by applying a bias potential of ±0.5 V to the polymer film enabling or respectively suppressing the expulsion of the model drug. In vitro tests showed excellent biocompatibility of the presented system.

Concepts: Polymer, Chemical substance, Layer, Plastic, Control, Hybrid, Release, Polymers