Premature Degradation Research Articles

Antibacterial efficacy of triple-layered poly(lactic-co-glycolic acid)/nanoapatite/lauric acid guided bone regeneration membrane on periodontal bacteria.

A guided bone regeneration (GBR) membrane has been extensively used in the repair and regeneration of damaged periodontal tissues. One of the main challenges of GBR restoration is bacterial colonization on the membrane, constitutes to premature membrane degradation. Therefore, the purpose of this study was to investigate the antibacterial efficacy of triple-layered GBR membrane composed of poly(lactic-co-glycolic acid) (PLGA), nanoapatite (NAp) and lauric acid (LA) with two types of Gram-negative periodontal bacteria, Fusobacterium nucleatum and Porphyromonas gingivalis through a disc diffusion and bacterial count tests. The membranes exhibited a pattern of growth inhibition and killing effect against both bacteria. The increase in LA concentration tended to increase the bactericidal activities which indicated by higher diameter of inhibition zone and higher antibacterial percentage. It is shown that the incorporation of LA into the GBR membrane has retarded the growth and proliferation of Gram-negative periodontal bacteria for the treatment of periodontal disease.

EB1 modified HSA nanoparticles as non-viral delivery vectors-Influence of peptide concentration on cell uptake

Targeted nanoparticle-based gene therapy is a promising alternative to viral gene therapy approaches. The main limitations of non-viral delivery systems currently used are very low transfection efficiency, very high cytotoxicity, and lack of DNA protection leading to premature degradation. The aim of the present work was the development of a stable, biodegradable, nontoxic and plasmid-loaded human serum albumin (HSA)-based nanoparticle system. The nanoparticles were coupled to the cell penetrating peptide (CPP) EB1, a penetratin analogue, in different quantities to improve cell entry and transfection efficiency.

Kaempferol Modulates DNA Methylation and Downregulates DNMT3B in Bladder Cancer

Background: Genomic DNA methylation plays an important role in both the occurrence and development of bladder cancer. Kaempferol (Kae), a natural flavonoid that is present in many fruits and vegetables, exhibits potent anti-cancer effects in bladder cancer. Similar to other flavonoids, Kae possesses a flavan nucleus in its structure. This structure was reported to inhibit DNA methylation by suppressing DNA methyltransferases (DNMTs). However, whether Kae can inhibit DNA methylation remains unclear. Methods: Nude mice bearing bladder cancer were treated with Kae for 31 days. The genomic DNA was extracted from xenografts and the methylation changes was determined using an Illumina Infinium HumanMethylation 450 BeadChip Array. The ubiquitination was detected using immuno-precipitation assay. Results: Our data indicated that Kae modulated DNA methylation in bladder cancer, inducing 103 differential DNA methylation positions (dDMPs) associated with genes (50 hyper-methylated and 53 hypo-methylated). DNA methylation is mostly relied on the levels of DNMTs. We observed that Kae specifically inhibited the protein levels of DNMT3B without altering the expression of DNMT1 or DNMT3A. However, Kae did not downregulate the transcription of DNMT3B. Interestingly, we observed that Kae induced a premature degradation of DNMT3B by inhibiting protein synthesis with cycloheximide (CHX). By blocking proteasome with MG132, we observed that Kae induced an increased ubiquitination of DNMT3B. These results suggested that Kae could induce the degradation of DNMT3B through ubiquitin-proteasome pathway. Conclusion: Our data indicated that Kae is a novel DNMT3B inhibitor, which may promote the degradation of DNMT3B in bladder cancer.

Combination of Correctors Rescues CFTR Transmembrane-Domain Mutants by Mitigating their Interactions with Proteostasis

Background/Aims: Premature degradation of mutated cystic fibrosis transmembrane conductance regulator (CFTR) protein causes cystic fibrosis (CF), the commonest Mendelian disease in Caucasians. Despite recent advances in precision medicines for CF patients, many CFTR mutants have not been characterized and the effects of these new therapeutic approaches are still unclear for those mutants. Methods: Cells transfected or stably expressing four CFTR transmembrane-domain mutants (G85E, E92K, L1077P, and M1101K) were used to: 1) characterize the mutants according to their protein expression, thermal sensitivity, and degradation pathways; 2) evaluate the effects of correctors in rescuing them; and 3) explore the effects of correctors on CFTR interactions with proteostasis components. Results: All four mutants exhibited lower protein expression than did wild type-CFTR, and they were degraded by proteasomes and aggresomes. At low temperature, only cells expressing the mutants L1077P and M1101K exhibited increased CFTR maturation. Co-administration of C4 and C18 showed the greatest effect, restoring functional expression and partial stability of CFTR bearing E92K, L1077P, or M1101K at the cell surface. However, this treatment was inefficient in rectifying the defect of CFTR bearing G85E. Correctors rescued CFTR mutants by reducing their interactions with proteostasis components associated with protein retention in the endoplasmic reticulum and ubiquitination. Conclusion: Co-administration of C4 and C18 rescued CFTR transmembrane-domain mutants by remodeling the CFTR interactome.

LIPOSOMES CONTAINING PHYTOCHEMICALS FOR CANCER TREATMENT-AN UPDATE

Many phytochemicals exhibit promising effects in treatment and prevention of various cancers, but due to their poor water solubility, stability, bio-availability and target specificity make administering them at therapeutic doses impractical. This is especially true for curcumin, quercetin, resveratrol and berberine. There is rising activity in developing nano drug delivery systems for these phytochemicals. These nano drug delivery systems mainly include liposomes, micelles, solid lipid nanoparticles, nanoemulsions, which are biocompatible and biodegradable nanoparticles. These nanoparticles can increase the stability and aqueous solubility of phytochemicals. They can also be used as sustained drug delivery systems. Much work has also proven that they enhance the absorption and bioavailability of the phytochemicals, protect them from premature enzymatic degradation or metabolism, hence prolonging their circulation time. Besides these parameters, in this review, we have also mentioned the improved target specificity of phytochemicals to cancer cells or tumours via passive or targeted delivery. Hence, nanotechnology cleared the way for developing phytochemical-loaded nanoparticles for prevention and treatment of cancer.

Efficient gene delivery to primary human retinal pigment epithelial cells: The innate and acquired properties of vectors

The purpose of this study is designing non-viral gene delivery vectors for transfection of the primary human retinal pigment epithelial cells (RPE). In the design process of gene delivery vectors, considering physicochemical properties of vectors alone does not seem to be enough since they interact with constituents of the surrounding environment and hence gain new characteristics. Moreover, due to these interactions, their cargo can be released untimely or undergo degradation before reaching to the target cells. Further, the characteristics of cells itself can also influence the transfection efficacy. For example, the non-dividing property of RPE cells can impede the transfection efficiency which in most studies was ignored by using immortal cell lines. In this study, vectors with different characteristics differing in mixing orders of pDNA, PEI polymer, and PLGA/PEI or PLGA nanoparticles were prepared and characterized. Then, their characteristics and efficacy in gene delivery to RPE cells in the presence of vitreous or fetal bovine serum (FBS) were evaluated. All formulations showed no cytotoxicity and were able to protect pDNA from premature release and degradation in extracellular media. Also, the adsorption of vitreous or serum proteins onto the surface of vectors changed their properties and hence cellular uptake and transfection efficacy.

Development and characterisation of disulfiram-loaded PLGA nanoparticles for the treatment of non-small cell lung cancer

Non-Small Cell Lung Cancer (NSCLC) is the most common type of lung cancer in both men and women. A recent phase IIb study demonstrated that disulfiram (DSF) in combination with cisplatin and vinorelbine was well tolerated and prolonged the survival of patients with newly diagnosed NSCLC. However, DSF is rapidly (4min) metabolised in the bloodstream and it is this issue which is limiting its anticancer application in the clinic. We have recently demonstrated that a low dose of DSF-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles supplemented with oral Cu inhibited tumour growth and reduced metastasis in a xenograft mouse lung cancer model. Here we demonstrate the influence of PLGA polymer, stabilizer loading and molecular weight as well as sonication time on the characteristics, including DSF release and the cytotoxicity of 10% w/w DSF-loaded PLGA nanoparticles. The paper demonstrates that the choice of PLGA as no significance on the characteristics of the nanoparticles apart from their DSF release, which is due to the differing degradation rates of the polymers. However, increasing the loading and molecular weight of the stabilizer as well as the sonication time reduced the size of the nanoparticles, reduced their ability to protect the DSF from reacting with Cu and degrading in serum, while increasing their DSF release rate and cytotoxicity. Additionally, increasing the sonication time resulted in the premature degradation of the PLGA, which increased the permeability of the nanoparticles further decreasing their ability to protect DSF from reacting with Cu and degrading in serum, while increasing their DSF release rate and cytotoxicity.

CFTR-β-catenin interaction regulates mouse embryonic stem cell differentiation and embryonic development.

Cystic fibrosis transmembrane conductance regulator (CFTR) is a cAMP-regulated anion channel capable of conducting both Cl- and HCO3-, mutations of which cause cystic fibrosis (CF), a common autosomal recessive disease. Although CF patients are known to have varied degree of developmental problems, the biological role of CFTR in embryonic development remains elusive. Here, we show that CFTR is functionally expressed in mouse ESCs. CFTR-/- mESCs exhibit dramatic defect in mesendoderm differentiation. In addition, CFTR physically interacts with β-catenin, defect of which leads to premature degradation of β-catenin and suppressed activation of β-catenin signaling. Furthermore, knockdown of CFTR retards the early development of Xenopus laevis with impaired mesoderm/endoderm differentiation and β-catenin signaling. Our study reveals a previously undefined role of CFTR in controlling ESC differentiation and early embryonic development via its interaction with β-catenin, and provides novel insights into the understanding of embryonic development.

A Novel Bioresorbable Device as a Controlled Release System for Protecting Cells from Oxidative Stress from Alzheimer's Disease.

Bioresorbable electrospun fibres have highly functional features that can preserve drug efficacy, avoiding premature degradation, and control drug release rates over long periods. In parallel, it is known that Alzheimer's disease (AD) has been linked to impaired insulin signalling in the brain. Glucagon-like peptide 1 (GLP-1) analogues have beneficial effects on insulin release and possess exceptional neuroprotective properties. Herein, we describe for the first time the incorporation of a GLP-1 analogue, liraglutide, into electrospun poly (lactic acid) (PLA) fibres with in situ gelatin capsules, in order to provide the controlled release of liraglutide, improving neuroprotective properties. In this study, PLA, a bioresorbable polymer in which degradation products have neurogenesis characteristics, was electrospun and loaded with liraglutide. Moreover, PLA/liraglutide fibres were encapsulated with gelatin and were shown to have better properties than the non-encapsulated fibres in terms of the controlled release of liraglutide, which was accomplished in the present study for up to 60days. We observed that this biodevice was completely encapsulated with gelatin, which made the material more hydrophilic than PLA fibres alone and the biodevice was able to enhance fibroblast interaction and reduce mitochondrial stress in a neuroblastoma cell line. In this manner, this study introduces a new material which can improve neuroprotective properties from AD oxidative stress via the sustained long-lasting release of liraglutide. Graphical Abstract ᅟ.

The Phosphorolytic Exoribonucleases Polynucleotide Phosphorylase and RNase PH Stabilize sRNAs and Facilitate Regulation of Their mRNA Targets.

In many bacteria, Hfq-dependent base-pairing sRNAs facilitate rapid changes in gene expression that are critical for maintaining homeostasis and responding to stress and environmental changes. While a role for Hfq in this process was identified more than 2 decades ago, the identity and function of the other proteins required for Hfq-dependent regulation by sRNAs have not been resolved. Here, we demonstrate that PNPase and RNase PH, the two phosphorolytic RNases in E. coli, stabilize sRNAs against premature degradation and, in the case of PNPase, also accelerate regulation by sRNA-mRNA pairings for certain sRNAs. These findings are the first to demonstrate that RNase PH influences and supports sRNA regulation and suggest shared and distinct roles for these phosphorolytic RNases in this process.

Influence of Aromatic Hydrocarbons in Air on Spatial PEMFC Performance

The successful commercial deployment of proton exchange membrane fuel cells (PEMFCs) depends on the achievement of stringent performance and durability requirements. Currently, air is the most convenient oxidant for fuel cell applications, and its quality is an important consideration for operation because airborne contaminants can negatively affect fuel cell performance, cause premature degradation and decrease durability (1). Aromatic compounds are hazardous pollutants produced or used in many industrial processes. Benzene and naphthalene are the main representatives of aromatic hydrocarbons and are widely used as precursors for chemical syntheses. More than half of the entire benzene production is processed to styrene to manufacture polymers and plastics. Benzene is originated in the air from emissions of chemical plants, burning coal and oil, gasoline stations and vehicle exhausts. Naphthalene is used in the production of phthalic anhydride and as a pest control agent. Determination of the impact of C6H6 and C10H8 on PEMFC performance is critical to establish environmental requirements for fuel cell usage, define specifications for air filtration systems and support understanding of fundamental aspects of PEMFC operation and maintenance. A segmented cell and data acquisition system were used (2) with a commercially available 100 cm2 membrane/electrode assembly (MEA). Each electrode contained a Pt/C catalyst with a loading of 0.4 mgPt cm-2. A segmented SGL 25BC gas diffusion layer (GDL, 10 segments of 7.6 cm2) and a Teflon gasket were employed at the cathode whereas a single GDL piece was applied at the anode. The MEA was operated under galvanostatic control of the whole cell current. Other operating conditions were: 80°C, 48.3 kPagback pressure, 100/50% relative humidity and 2/2 stoichiometry for the anode and cathode respectively. The dry contaminant was injected into the humidified cathode air stream. The poisoning proceeded until the cell voltage reached a steady value. Subsequently, the contaminant injection was stopped to evaluate the cell self-recovery. Fig. 1 a) shows the voltage response and normalized current density for each segment at 1.0 A cm-2 under benzene contamination. For the first 18 hours, the cell was operated with pure air resulting in a cell voltage of 0.670 V. The injection of 2 ppm C6H6 decreased the voltage to a steady state of 0.560 V and caused a redistribution of local current densities. Operation with pure air fully recovered the initial cell performance. Effects of naphthalene are shown in Fig. 1 b). The introduction of 2.3 ppm C10H8to air stream led to a significant voltage drop within 10 h and a different current redistribution pattern. Voltage oscillations from 0.100 to 0.170 V were observed as soon as the cell reached 0.12 V. Recovery took 2 h and was accompanied by further redistribution of localized currents. Benzene and naphthalene have similar electrochemical properties (3, 4). Cathodic desorption of the adsorbed species on Pt occurs at hydrogen adsorption potentials (< 0.1 V) and is accompanied by partial hydrogenation, while electrooxidation takes place at 1.35 V with formation of CO2 as the main product. The strong adsorption of C6H6 and C10H8 occurs at 0.1-0.6 V without electrochemical reactions, and results in an in-plane adsorbate configuration due to the interaction between the aromatic ring and the Pt surface (5). Contaminant adsorption results in a decrease of the electrochemical area, suppression of O2 adsorption and shift the oxygen reduction from a 4-electron to a 2-electron mechanism, which negatively impact PEMFC performance. The data demonstrated that C10H8 has a severer effect on PEMFC than C6H6 which is most likely due to a higher adsorption energy and abilty to form multilayer adsorption (6, 7). A detailed discussion of the results and a poisoning mechanism will be presented. ACKNOWLEDGMENTS We gratefully acknowledge ONR (N00014-13-1-0463), DOE EERE (DE-EE0000467) and Hawaiian Electric Company. REFERENCES O.A. Baturina, Y. Garsany, B.D. Gould, K.E. Swider-Lyons, in: H. Wang, H. Li, X.-Z. Yuan (Eds.), PEM fuel cell failure mode analysis, CRC Press, 2011, p. 199.T.V. Reshetenko, G. Bender, K. Bethune, R. Rocheleau, Electrochim. Acta, 56, 8700 (2011).F. Montilla, F. Huerta, E. Morallon, J.L. Vazquez, Electrochim. Acta, 45, 4271 (2000).T. Löffler, E. Drbalkova, P. Janderka, P. Königshoven, H. Baltruschat, J. Electroanal. Chem., 550-551, 81 (2003).M.P. Soriaga, A.T. Hubbard, J. Am. Chem. Soc., 104, 2735 (1982).C. Morin, D. Simon, P. Sautet, J. Phys. Chem. B, 108, 12084 (2004).J.M. Gottfried, E.K. Vestergaard, P. Bera, C.T. Campbell, J. Phys. Chem. B, 110, 17539 (2006). Figure 1

Composition analysis and characterization of waste polyvinyl chloride (PVC) recovered from data cables

Cables and wires are the indispensable parts of electronic equipments for transmission of both information and electricity. Nowadays, data cables are widely used in the computer equipments for sending information and they become waste once its life cycle is completed. However, recycling of cables and wires are mainly concentrating into the recovery of metals such as aluminium and copper, rather than other polymer present. Polymeric materials from the waste data cables are often disposed into landfills or incinerated, since they have only lower value in recycling yard. From the data cables collected, it has been estimated that the major constituents are copper (58.3%), polyvinyl chloride (19.9%) and polyethylene (16%). Similarly, polycarbonate (2.9%), silicon rubber (1.6%), steel (1.4%) and other material (0.4%) such as cotton cord were also present as minor components. Out of these, polyvinyl chloride is the dominant polymer present in data cables. Hence, the present work investigates the reprocessability of the polyvinyl chloride recovered from the data cables and deals with issues such as premature degradation during life cycle, assessment of plasticizers and degradation after reprocessing. Torque measurement studies using torque rheometer revealed further mechanical recycling possibilites of the recovered polyvinyl chloride. Besides, the applicability of melt blending technique for processing recovered polyvinyl chloride can be found out by analysing thermal behaviour by using thermogravimetric analysis, differential scanning calorimetry and heat distortion temperature.

Degradation of Glucan Primers in the Absence of Starch Synthase 4 Disrupts Starch Granule Initiation in Arabidopsis

Arabidopsis leaf chloroplasts typically contain five to seven semicrystalline starch granules. It is not understood how the synthesis of each granule is initiated or how starch granule number is determined within each chloroplast. An Arabidopsis mutant lacking the glucosyl-transferase, STARCH SYNTHASE 4 (SS4) is impaired in its ability to initiate starch granules; its chloroplasts rarely contain more than one large granule, and the plants have a pale appearance and reduced growth. Here we report that the chloroplastic α-amylase AMY3, a starch-degrading enzyme, interferes with granule initiation in the ss4 mutant background. The amy3 single mutant is similar in phenotype to the wild type under normal growth conditions, with comparable numbers of starch granules per chloroplast. Interestingly, the ss4 mutant displays a pleiotropic reduction in the activity of AMY3. Remarkably, complete abolition of AMY3 (in the amy3 ss4 double mutant) increases the number of starch granules produced in each chloroplast, suppresses the pale phenotype of ss4, and nearly restores normal growth. The amy3 mutation also restores starch synthesis in the ss3 ss4 double mutant, which lacks STARCH SYNTHASE 3 (SS3) in addition to SS4. The ss3 ss4 line is unable to initiate any starch granules and is thus starchless. We suggest that SS4 plays a key role in granule initiation, allowing it to proceed in a way that avoids premature degradation of primers by starch hydrolases, such as AMY3.

Disulfide-functional poly(amido amine)s with tunable degradability for gene delivery

Controlled degradability in response to the local environment is one of the most effective strategies to achieve spatiotemporal release of genes from a polymeric carrier. Exploiting the differences in reduction potential between the extracellular and intracellular environment, disulfides are frequently incorporated into the backbone of polymeric drug delivery agents to ensure efficient intracellular release of the payload. However, although to a lesser extent, reduction of disulfides may also occur in the extracellular environment and should be prevented to avoid premature release. Accurate control over the stability of disulfide linkages enables the optimization of polymeric carriers for efficient drug delivery. Bioreducible poly(amido amine)s (PAAs) with varying degrees of steric hindrance adjacent to the disulfide bonds (0, 2 or 4 methyl groups) were prepared in order to obtain carriers with controlled stability. The degradation behavior of these PAA-polymers was evaluated under different reducing conditions and their in vitro toxicities and transfection efficiencies were assessed. Degradation of the PAA-based polyplexes consistently required higher reducing strengths as the steric hindrance near the disulfide bonds increased. Polyplexes based on 2-methyl cystamine disulfide based PAA polymer (PAA2m) remained stable under extracellular glutathione concentrations (0.001–0.01mM), while degrading within 1h under reducing conditions similar to those in the intracellular environment (1–10mM glutathione). This polymer exhibited excellent transfection capabilities, with efficiencies up to 90% of transfected cells. PAA0m showed slightly reduced transfection properties compared to PAA2m, likely due to premature degradation. The severely hindered PAA4m, however, displayed increased toxicity, accompanied by reduced transfection efficiency, as a result of its exceptional stability. These results demonstrate the feasibility of introducing steric hindrance near the disulfide moiety to tune polyplex stability against bioreduction, and show that PAA2m is a promising polymer to be further developed for gene therapy.

Advances in Controlled Drug Delivery for Treatment of Osteoporosis.

Osteoporosis, which is characterized by resorption of bone exceeding formation, remains a significant human health concern, and the impact of this condition will only increase with the "graying" of the worldwide population. This review focuses on current and emerging approaches for delivering therapeutic agents to restore bone remodeling homeostasis. Well-known antiresorptive and anabolic agents, such as estrogen, estrogen analogs, bisphosphonates, calcitonin, and parathyroid hormone, along with newer modulators and antibodies, are primarily administered orally, intravenously, or subcutaneously. Although these treatments can be effective, continuing problems include patient noncompliance and adverse systemic or remote-site effects. Controlled drug delivery via polymeric, targeted, and active release systems extends drug half-life by shielding against premature degradation and improves bioavailability while also providing prolonged, sustained, or intermittent release at therapeutic doses to more effectively treat osteoporosis and associated fracture risk.

Novel Polymeric Nanoformulation of Mancozeb – An Eco-Friendly Nanomaterial

The best alternative to conventional pesticides is nanopesticide. Severe pollution is caused due to the rapid degradation and uncontrolled, unconstrained utilization of conventional pesticides. Nanopesticides can provide better penetration through the plants and control different diseases. Nanoformulation of pesticide certainly protects the premature degradation in the environment and delivers high impact on target species. Less environmental contamination and safe handling are the advantages of nanopesticides. In this paper, we reported the novel nano-mancozeb pesticide for plant disease control. Our study provides a novel nanoformulation of mancozeb pesticide by using Polyethylene glycol as a capping agent. Nanoparticles of the encapsulated complex were characterized by UV-Vis, Dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscope (SEM), and transmission electron microscopy (TEM). Biological evaluation was conducted against Candida albicans and Staphylococcus aureus. The developed method is useful to farmers and it is an eco-friendly pesticide formulation.

Pharmacological Correction of Cystic Fibrosis: Molecular Mechanisms at the Plasma Membrane to Augment Mutant CFTR Function.

In the late 1980s, a loss-of-function mutation in the gene encoding for the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel was identified to be the primary cause of cystic fibrosis (CF); a fatal multiple-organ disorder that mostly affects Caucasians. To date, approximately 2000 genetic mutations have been identified in the CFTR gene (http://www.genet.sickkids.on.ca/cftr/app). The most common cause of morbidity and mortality in persons with CF is a progressive deterioration in lung function leading ultimately to respiratory collapse. The median life expectancy of CF patients currently is estimated to be 39 years in the US. The most prevalent CFTR mutation, F508del, accounts for 70% of CF cases and causes a processing defect in the protein leading to premature endoplasmic reticulum-associated degradation (ERAD) and reduced F508del-CFTR delivery to the cell surface. A CF corrector is defined as a chemical chaperone that increases cell-surface levels of F508del-CFTR. A series of CF correctors have been developed, and VX-809 (lumacaftor) has been cited as the most effective symptomatic CF corrector to date. VX-809 improves the function of the mutant protein by approximately 15% in in vitro culture systems. However, this effect did not completely translate clinically, with only a marginal improvement observed in lung function of the F508del-homozygous patients undergoing the therapy. New studies revealed that even after successful ER retrieval, rescued F508del-CFTR (rF508del-CFTR) once at the cell surface does not function properly, exhibiting poor stability and channel gating and structural abnormalities. This becomes further complicated by the existence of genes termed CFTR modifiers, which can alter CFTR function to be additionally defective and exacerbate the CF phenotype while also alternatively suggested be potentially targeted to improve F508del-CFTR functional outcome. It is necessary to understand the biology of F508del-CFTR post-ER and at the plasma membrane where the protein might also confront the modifiers and how we can incorporate these components into CF therapeutics. Additionally, the notion that CF individuals would eventually benefit from more of a personalized medicine is becoming increasingly accepted. Here, we review how CF therapeutics may be simplified by understanding the complexities of rescued F508del-CFTR biology and eventually move toward more personalized medicine for patients suffering with CF.

The S. pombe mRNA decapping complex recruits cofactors and an Edc1-like activator through a single dynamic surface.

The removal of the 5′ 7-methylguanosine mRNA cap structure (decapping) is a central step in the 5′–3′ mRNA degradation pathway and is performed by the Dcp1:Dcp2 decapping complex. The activity of this complex is tightly regulated to prevent premature degradation of the transcript. Here, we establish that the aromatic groove of the EVH1 domain of Schizosaccharomyces pombe Dcp1 can interact with proline-rich sequences in the exonuclease Xrn1, the scaffolding protein Pat1, the helicase Dhh1, and the C-terminal disordered region of Dcp2. We show that this region of Dcp1 can also recruit a previously unidentified enhancer of decapping protein (Edc1) and solved the crystal structure of the complex. NMR relaxation dispersion experiments reveal that the Dcp1 binding site can adopt multiple conformations, thus providing the plasticity that is required to accommodate different ligands. We show that the activator Edc1 makes additional contacts with the regulatory domain of Dcp2 and that an activation motif in Edc1 increases the RNA affinity of Dcp1:Dcp2. Our data support a model where Edc1 stabilizes the RNA in the active site, which results in enhanced decapping rates. In summary, we show that multiple decapping factors, including the Dcp2 C-terminal region, compete with Edc1 for Dcp1 binding. Our data thus reveal a network of interactions that can fine-tune the catalytic activity of the decapping complex.

Targeting duplex DNA with the reversible reactivity of quinone methides.

DNA alkylation and crosslinking remains a common and effective strategy for anticancer chemotherapy despite its infamous lack of specificity. Coupling a reactive group to a sequence-directing component has the potential to enhance target selectivity but may suffer from premature degradation or the need for an external signal for activation. Alternatively, quinone methide conjugates may be employed if they form covalent but reversible adducts with their sequence directing component. The resulting self-adducts transfer their quinone methide to a chosen target without an external signal and avoid off-target reactions by alternative intramolecular self-trapping. Efficient transfer is shown to depend on the nature of the quinone methide and the sequence-directing ligand in applications involving alkylation of duplex DNA through a triplex recognition motif. Success required an electron-rich derivative that enhanced the stability of the transient quinone methide intermediate and a polypyrimidine strand of DNA to associate with its cognate polypurine/polypyrimidine target. Related quinone methide conjugates with peptide nucleic acids were capable of quinone methide transfer from their initial precursor but not from their corresponding self-adduct. The active peptide nucleic acid derivatives were highly selective for their complementary target.

Simulating the effect of roughness of the bond coat surface on stress distribution in EB-PVD thermal barrier coatings with finite element method

Thermal barrier coatings are widely used in gas turbine motors in air and ground sections (electricity generation). One of the challenges in developing these coatings is the fracture occurring around the interface of the ceramic layer with thermally grown oxide layer. These fractures result from the accumulation of energy around this area. Important parameters influencing stress distribution and fracture of thermal barrier are the roughness of the bond coat layer, the thickness of the coating and the mechanical properties of the coating components. In this paper, the effect of the roughness of the bond coat surface on stress distribution in different parts of thermal barrier coatings resulting from electron beam physical vapor deposition (EB-PVD) process was studied. The results indicated increase in roughness enhanced the curvature area, premature degradation of coating system led to thermal barrier.