Search

Analogues and derivatives of nucleic acid components have been used as key drugs in different areas of medicine over the past decades. The replacement of one or more nitrogen atoms of the heterocyclic base with a CH group affords deazapurine nucleoside analogues, and the replacement of the methine group with a nitrogen atom gives azapurine derivatives. A combination of aza and deaza moieties in the purine base leads to aza(deaza)-modified bases. Some nucleoside analogues were found to exhibit pronounced anticancer and antiviral activity. The synthesis and evaluation of biological activity of aza- and deazapurine nucleoside analogues have attracted interest from researchers four decades ago. This review describes and integrates the studies concerning certain aspects of the synthesis and(or) activity of various representatives of this class of compounds. The structure–biological activity relationships are analyzed. The successful approaches to the design of aza- and deazapurine nucleoside analogues are considered. A comparison is given for the methods of chemical and enzymatic synthesis of these compounds. The bibliography includes 161 references.

Hydrogen production in the microfluidic alkaline membraneless electrolyzer (μAME) marks a new paradigm in sustainable energy technology. One challenge in this field is implementing a bifunctional c...

Spironolactone reduces morbidity and mortality in patients with heart failure (HF) with reduced ejection fraction (EF) and decreases hospitalizations in HF with preserved EF. To minimize the risk of hyperkalemia, patients must have an estimated glomerular filtration rate (eGFR) > 30 mL/min/1.73 m2 and potassium 40% and 47.9% (n = 58) had an EF ≤ 40% with 69.4% (n = 84) CKD stage 3, 24.8% (n = 30) stage 4, and 5.8% (n = 7) stage 5. Spironolactone was initiated prior to admission (PTA) for 54.5% (n = 66) of patients, while 45.5% (n = 55) of orders were initiated during hospitalization. Eight patients (6.6%) experienced inpatient hyperkalemia—all with PTA spironolactone. Patients who experienced inpatient hyperkalemia had a numerically lower eGFR that was not statistically significant (35.40 vs. 38.22 mL/min/1.73 m2; p = 0.730). Patients with CKD stage 3 (n = 4) had numerically higher rates of inpatient hyperkalemia than stages 4 (n = 1) or 5 (n = 3) (50%, 12.5%, and 37.5% respectively; p

The data of transmission electron microscopy (TEM) on morphology of M. tuberculosis H37Rv bacterial cells treated with four analogues of pyrimidine nucleosides with different substituents at 5 position of base are presented. We showed that the growth of M. tuberculosis H37Rv cells effectively inhibited by each of these compounds. This process is accompanied with the accumulation of lipid intracellular vacuole-like inclusions in the cells, appearance of deep protrusions and indentations on the surface, partial and/or complete destruction of the three-layered cell envelope. The exact molecular mechanism of action of 5-substituted pyrimidine nucleosides on M. tuberculosis cells remains to be proved. However, one can suggest that mechanism of action for these compounds is related either to their direct interactions with bacteria cell walls or to interactions with enzymes participating in the process of cell wall formation.

We present a nanozyme-based biosensor fabricated from nanostructured Ni films deposited onto a silicon wafer by glancing angle deposition (GLAD) for enzyme-free colorimetric monitoring of uric acid (UA), a biomarker for gout, high blood pressure, heart disease, and kidney disease. The helically structured Ni GLAD nanozymes exhibit excellent peroxidase-like activity to accelerate the oxidation reaction of colorless 3,3′,5,5′-tetramethylbenzidine (TMB) to a blue product, oxidized TMB (oxTMB), mediated by H2O2. In the presence of UA, oxTMB is reduced, decreasing the optical absorbance by an amount determined by the concentration of UA in the solution. The nanozyme not only mimics peroxidase but also possesses the notable qualities of reusability, simple operation, and reliability, making it environment-friendly and suitable for on-demand analysis. We optimized essential working parameters (pH, TMB concentration, and H2O2 concentration) to maximize the initial color change of the TMB solution. The catalytic activity of this nanozyme was compared with conventional nanofilms using the Michaelis–Menten theory. Based on this, enzyme-free biosensors were developed for colorimetric detection of UA, providing a wide detection range and a limit of detection (3.3 μM) suitable for measurements of UA concentration in sweat. Furthermore, interference from glucose and urea was studied so as to explore the potential of the biosensor for use in the clinical diagnosis of UA biomarkers.

Current guidelines recommend direct-acting oral anticoagulants (DOACs) over warfarin in patients with atrial fibrillation (AF) and valvular heart disease (VHD) without a mechanical valve or moderate to severe mitral stenosis. However, real-world data to support the safety and efficacy of DOACs in this patient population are lacking. Our objective was to assess the safety and effectiveness of DOACs in patients with AF and VHD. This retrospective chart review evaluated patients aged ≥ 18 years with a diagnosis of AF and at least moderate VHD on echocardiogram. Patients were included if they received ≥ 1 month of DOAC therapy from December 2016 to December 2018. Patients were excluded if they received dual antiplatelet therapy or had additional indications for anticoagulation. The primary outcomes were incidence of stroke or systemic embolism (SSE) and major bleeding. In total, 200 patients were included (disease type: aortic, n = 50; mitral, n = 50; tricuspid, n = 50; multivalve, n = 50). Most patients received apixaban (n = 133 [66.5%]) followed by rivaroxaban (n = 50 [25%]) and dabigatran (n = 17 [8.5%]). No patients received edoxaban. The mean CHA2DS2-VASc score was 4.25 and was similar among DOAC cohorts (p = 0.380). The overall SSE rate was 3.5% and was highest for dabigatran (n = 3 [17.6%]) compared with the other DOACs (apixaban, n = 1 [0.8%]; rivaroxaban, n = 3 [6%]; p = 0.001). Rates were similar among different valve types (aortic, n = 3 [6%]; mitral, n = 1 [2%]; tricuspid, n = 2 [4%]; multivalve, n = 1 [2%]; p = 0.653). The overall rate of major bleeding was 5.5% and did not differ among the DOACs (apixaban, n = 5 [3.8%]; rivaroxaban, n = 4 [8%]; dabigatran, n = 2 [11.8%]; p = 0.264) or valve type (aortic, n = 3 [6%]; mitral, n = 2 [4%]; tricuspid, n = 2 [4%]; multivalve, n = 4 [8%]; p = 0.787). In patients with AF and VHD, rates of major bleeding were similar among the DOACs and valve types; however, more patients receiving dabigatran experienced SSE. Further studies are needed to validate these findings.

A series of uracil derivatives containing a 4-oxoquinazoline fragment bound to the nitrogen atom N3 of the pyrimidine ring by a short methylene bridge was synthesized to search for new antiviral agents. Some compounds in this series are shown to exhibit high inhibitory activity against human cytomegalovirus and the varicella zoster virus in a HEL cell culture. ispartof: ACTA NATURAE vol:12 issue:3 pages:134-139 ispartof: location:Russia (Federation) status: accepted

Smart materials that can undergo changes in color upon the detection of amines have the potential to provide information on the freshness of fish and meat. To engineer a material that undergoes a change in color upon exposure to biogenic amines, succinic anhydride functional groups - which are deprotonated in the presence of amines - are grafted onto a biopolymer poly(lactic acid) backbone. This material is then blended with a pH sensitive dye, yielding a material that shows a highly specific response to amines. In this system, the reaction between SAh and amines protonates the dye and leads to an irreversible change in color in the indicators. The resulting change in color was recorded and monitored with standardized photos and UV-Vis spectroscopy. Initially, indicators of different degrees of SAh (from 5 wt% to 45 wt%) grafted onto PLA were exposed to the vapours from a 400 ppm amine solution. The samples with higher degrees of grafting underwent the most visible changes in color. A more detailed study of the effect of temperature and amine concentration was performed on indicators with 30 wt% SAh. The limits of detection, half-time and kinetics of the response are also presented. Higher temperatures and concentrations were found to increase the degree of the color change while decreasing the half-time of the response of the indicators. This work shows potential opportunities for the development of simple real-time amine indicators.

Membrane-less microfluidic reactors for water electrolysis can serve as a disruptive technology for the sustainable production of hydrogen utilizing excess electricity from intermittent renewable energy sources. Membrane-less electrolyzers facilitate flexible pH operation of electrolyzers using liquid electrolytes, which have higher ionic conductivity than solid membranes. Herein, we demonstrate a microfluidic electrolyzer driven by electrochemical neutralization energy in which an asymmetric electrolyte configuration (acidic catholyte and alkaline anolyte) was used for the first time to reduce the voltage requirement of water electrolysis drastically. The potential recorded for water electrolysis in this device was 1.3 V for an asymmetric electrolyte, 1.96 V for an acidic electrolyte, and 1.94 V for an alkaline electrolyte. The product gas separation was attained by balancing inertial and viscous forces acting on the fluid induced by the flow of electrolyte. The flow in the microchannel was characterized by a low Reynolds number (43.94) and high Peclet number (7.29 × 103 and 1.75 × 104 for H2 and O2, respectively), which implies a highly viscous flow and negligible diffusion of gas products across the electrodes. The charge transfer resistance for water electrolysis with an asymmetric electrolyte was less (47.2 Ω cm2) as compared to acidic (272.94 Ω cm2) and alkaline electrolytes (292.92 Ω cm2). The reactor exhibits 4 hours of stability with no perturbation in current density at a 1.4 ml min−1 electrolyte flow rate. The product crossover analyzed by gas chromatography was less than 5% with H2 and O2 volumetric collection efficiencies of 93.14% and 91.43%, respectively. The device has a performance efficiency of 96.5% based on a 150 μm interelectrode distance.

We demonstrate a simple, nonlithographic method for fabricating piezoresistive pressure sensors with a broad range of working pressures and low detection limit. Our wearable pressure sensor is fabr...

Optimal lysosome function requires maintenance of an acidic pH maintained by proton pumps in combination with a counterion transporter such as the Cl(−)/H(+) exchanger, CLCN7 (ClC-7), encoded by CLCN7. The role of ClC-7 in maintaining lysosomal pH has been controversial. In this paper, we performed clinical and genetic evaluations of two children of different ethnicities. Both children had delayed myelination and development, organomegaly, and hypopigmentation, but neither had osteopetrosis. Whole-exome and -genome sequencing revealed a de novo c.2144A>G variant in CLCN7 in both affected children. This p.Tyr715Cys variant, located in the C-terminal domain of ClC-7, resulted in increased outward currents when it was heterologously expressed in Xenopus oocytes. Fibroblasts from probands displayed a lysosomal pH approximately 0.2 units lower than that of control cells, and treatment with chloroquine normalized the pH. Primary fibroblasts from both probands also exhibited markedly enlarged intracellular vacuoles; this finding was recapitulated by the overexpression of human p.Tyr715Cys CLCN7 in control fibroblasts, reflecting the dominant, gain-of-function nature of the variant. A mouse harboring the knock-in Clcn7 variant exhibited hypopigmentation, hepatomegaly resulting from abnormal storage, and enlarged vacuoles in cultured fibroblasts. Our results show that p.Tyr715Cys is a gain-of-function CLCN7 variant associated with developmental delay, organomegaly, and hypopigmentation resulting from lysosomal hyperacidity, abnormal storage, and enlarged intracellular vacuoles. Our data supports the hypothesis that the ClC-7 antiporter plays a critical role in maintaining lysosomal pH.

Photomediated Giese reactions are at the forefront of radical chemistry, much like the classical tin-mediated Giese reactions were nearly forty years ago. With the global recognition of organometallic photocatalysts for the mild and tunable generation of carbon-centered radicals, chemists have developed a torrent of strategies to form previously inaccessible radical intermediates that are capable of engaging in intermolecular conjugate addition reactions. This Review summarizes advances in photoredox-mediated Giese reactions since 2013, with a focus on the breadth of methods that provide access to crucial carbon-centered radical intermediates that can engage in radical conjugate addition processes.

Nucleoside analogues have long served as key chemotherapeutic drugs for the treatment of viral infections and cancers. Problems associated with the development of drug resistance have led to a search for the design of nucleosides capable of bypassing point mutations in the target enzyme's binding site. As a possible answer to this, the Seley-Radtke group developed a flexible nucleoside scaffold (fleximers), where the heterocyclic purine base is split into its two components, i.e. pyrimidine and imidazole. Herein, we present a series of new pyrazole-containing flex-bases and the corresponding fleximer analogues of 8-aza-7-deaza nucleosides. Subsequent studies found that pyrazole-containing flex-bases are substrates of purine nucleoside phosphorylase (PNP). We have compared the chemical synthesis of fleximers and enzymatic approaches with both isolated enzymes and the use of E. coli cells overproducing PNP. The latter provided stereochemically pure pyrazole-containing β-D-ribo- and β-D-2′-deoxyribo-fleximers and are beneficial in terms of environmental issues, are more economical, and streamline the steps required from a chemical approach. The reaction is carried out in water, avoiding hazardous chemicals, and the products are isolated by ion-exchange chromatography using water/ethanol mixtures for elution. Moreover, the target nucleosides were obtained on a multi-milligram scale with >97–99% purity, and the reactions can be easily scaled up.

Nitrogen-functionalization is an effective means of improving the catalytic performances of nanozymes. In the present work, plasma-assisted nitrogen modification of nanocolumnar Ni GLAD films was performed using an ammonia plasma, resulting in an improvement in the peroxidase-like catalytic performance of the porous, nanostructured Ni films. The plasma-treated nanozymes were characterized by TEM, SEM, XRD, and XPS, revealing a nitrogen-rich surface composition. Increased surface wettability was observed after ammonia plasma treatment, and the resulting nitrogen-functionalized Ni GLAD films presented dramatically enhanced peroxidase-like catalytic activity. The optimal time for plasma treatment was determined to be 120 s; when used to catalyze the oxidation of the colorimetric substrate TMB in the presence of H2O2, Ni films subjected to 120 s of plasma treatment yielded a much higher maximum reaction velocity (3.7⊆10−8 M/s vs. 2.3⊆10−8 M/s) and lower Michaelis-Menten coefficient (0.17 mM vs. 0.23 mM) than pristine Ni films with the same morphology. Additionally, we demonstrate the application of the nanozyme in a gravity-driven, continuous catalytic reaction device. Such a controllable plasma treatment strategy may open a new door toward surface-functionalized nanozymes with improved catalytic performance and potential applications in flow-driven point-of-care devices.

Although understudied relative to many phospholipids, accumulating evidence suggests that bis(monoacylglycero)phosphate (BMP) is an important class of regulatory lipid that plays key roles in lysosomal integrity and function. BMPs are rare in most mammalian tissues, comprising only a few percent of total cellular lipid content, but are elevated in cell types such as macrophages that rely heavily on lysosomal function. BMPs are markedly enriched in endosomal and lysosomal vesicles compared to other organelles and membranous structures, and their unique sn-1:sn-1′ stereoconfiguration may confer stability within the hydrolytic lysosomal environment. BMP-enriched vesicles serve in endosomal-lysosomal trafficking and function as docking structures for the activation of lysosomal hydrolytic enzymes, notably those involved in the catabolic breakdown of sphingolipids. BMP levels are dysregulated in lysosomal storage disorders, phospholipidosis, metabolic diseases, liver and kidney diseases and neurodegenerative disorders. However, whether BMP alteration is a mediator or simply a marker of pathological states is unclear. Likewise, although BMP acyl chain composition may be altered with disease states, the functional significance of specific BMP species remains to be resolved. Newly developed tools for untargeted lipidomic analysis, together with a deeper understanding of enzymes mediating BMP synthesis and degradation, will help shed further light on the functional significance of BMPs in cellular physiology and pathology.

Widespread latent herpes viral infections within a population can lead to the development of co-infections in HIV-infected patients. These infections are not particularly dangerous for healthy individuals and often occur with minimal symptoms, but for those who are immunocompromised, these infections can accelerate the acute phase of HIV infection and AIDS. Thus, the idea of designing compounds that could combine activity against HIV and co-infections would seem promising. In that regard, eleven compounds were synthesized that represent conjugates of non-nucleoside HIV reverse transcriptase inhibitors and nucleoside inhibitors of the herpes family viruses with the hope that these novel heterodimers will result in dual activity against HIV and concomitant herpes virus infections. ispartof: MOLECULES vol:25 issue:15 ispartof: location:Switzerland status: published

A general method for the N-arylation of sulfamides with aryl bromides is described. The protocol leverages a dual-catalytic system, with [Ir(ppy)2(dtbbpy)]PF6 as a photosensitizer, NiBr2·glyme as a precatalyst, and 1,8-diazabicyclo(5.4.0)undec-7-ene (DBU) as a base, and proceeds at room temperature under visible light irradiation. Using these tactics, aryl boronic esters and aryl chlorides can be carried through the reaction untouched. The developed reactions efficiently engage simple bromoarenes and primary sulfamides in between 66% and quantitative yields. For more challenging substrates, such as secondary sulfamides, the reaction efficiency is documented. Thereby, these methods complement the known Buchwald-Hartwig coupling methods for N-arylation of sulfamides.

Heterologous production of extracellular polyhydroxybutyrate (PHB) depolymerases (PhaZs) has been of interest for over 30 years, but implementation is sometimes difficult and can limit the scope of research. With the constant development of tools to improve recombinant protein production in Escherichia coli, we propose a method that takes characteristics of PhaZs from different bacterial strains into account. Recombinant His‐tagged versions of PhaZs (rPhaZ) from Comamonas testosteroni 31A, Cupriavidus sp. T1, Marinobacter algicola DG893, Pseudomonas stutzeri, and Ralstonia sp. were successfully produced with varying expression, solubility, and purity levels. PhaZs from C. testosteroni and P. stutzeri were more amenable to heterologous expression in all aspects; however, using the E. coli Rosetta‐gami B(DE3) expression strain and establishing optimal conditions for expression and purification (variation of IPTG concentration and use of size exclusion columns) helped circumvent low expression and purity for the other PhaZs. Degradation activity of the rPhaZs was compared using a simple PHB plate‐based method, adapted to test for various pH and temperatures. rPhaZ from M. algicola presented the highest activity at 15°C, and rPhaZs from Cupriavidus sp. T1 and Ralstonia sp. had the highest activity at pH 5.4. The methods proposed herein can be used to test the production of soluble recombinant PhaZs and to perform preliminary evaluation for applications that require PHB degradation., A rapid, efficient approach for the expression of active recombinant extracellular polyhydroxybutyrate (PHB) depolymerases originating from various bacterial strains. It enables the characterization of new PHB depolymerases and the direct comparison of activity between enzymes and conditions; as an example, the activity of five PHB depolymerases is evaluated and compared at different pH and temperatures. This approach can accelerate the investigation and development of applications based on the degradation of biopolymers.

Purpose: To characterize the ionizing radiation (IR) enhancing effects and underlying mechanisms of the CDK4/6 inhibitor abemaciclib in non–small cell lung cancer (NSCLC) cells in vitro and in vivo. Experimental Design: IR enhancement by abemaciclib in a variety of NSCLC cell lines was assessed by in vitro clonogenic assay, flow cytometry, and target inhibition verified by immunoblotting. IR-induced DNA damage repair was evaluated by γH2AX analysis. Global metabolic alterations by abemaciclib and IR combination were evaluated by LC/MS mass spectrometry and YSI bioanalyzer. Effects of abemaciclib and IR combination in vivo were studied by xenograft tumor regrowth delay, xenograft lysate immunoblotting, and tissue section immunohistochemistry. Results: Abemaciclib enhanced the radiosensitivity of NSCLC cells independent of RAS or EGFR status. Enhancement of radiosensitivity was lost in cell lines deficient for functional p53 and RB protein. After IR, abemaciclib treatment inhibited DNA damage repair as measured by γH2AX. Mechanistically, abemaciclib inhibited RB phosphorylation, leading to cell-cycle arrest. It also inhibited mTOR signaling and reduced intracellular amino acid pools, causing nutrient stress. In vivo, abemaciclib, when administered in an adjuvant setting for the second week after fractionated IR, further inhibited vasculogenesis and tumor regrowth, with sustained inhibition of RB/E2F activity, mTOR pathway, and HIF-1 expression. In summary, our study signifies inhibiting the CDK4/6 pathway by abemaciclib in combination with IR as a promising therapeutic strategy to treat NSCLC. Conclusions: Abemaciclib in combination with IR enhances NSCLC radiosensitivity in preclinical models, potentially providing a novel biomarker-driven combination therapeutic strategy for patients with NSCLC. Clin Cancer Res; 24(16); 3994–4005. ©2018 AACR.

Graphenic material/biopolymer nanocomposites have attracted attention for use in next generation flexible and degradable electronics. However, achieving high electrical conductivity (above 10 S/m) and favorable mechanical properties in such materials remains a challenge. In this work, reduced graphene oxide (rGO)/polyhydroxybutyrate (PHB) films were both prepared from solution. The following three reducing agents were investigated: sodium borohydride, hydrazine, and l-ascorbic acid. For the first two reducing agents (sodium borohydride and hydrazine), GO was first reduced and then added to the dissolved PHB, whereas for the third reducing agent (l-ascorbic acid) an in situ reduction was performed. We systematically investigated the effects of the three reducing agents by comparing their reduction efficiency, the residual functional groups presented on the GO, and the properties of the resulting composites of all the composites, reduction by l-ascorbic acid gives the lowest electrical percolation threshold...

Sourced from agricultural waste, hemp hurds are a low-cost renewable material with high stiffness, however, despite their potential to be used as low-cost filler in natural fiber reinforced polymer biocomposites, they are often discarded. In this study, the potential to add value to hemp hurds by incorporating them into poly(lactic acid) (PLA) biopolymer to form bio-based materials for packaging applications is investigated. However, as with many plant fibers, the inherent hydrophilicity of hemp hurds leads to inferior filler-matrix interfacial interactions, compromising the mechanical properties of the resulting biocomposites. In this study, two chemical treatments, alkaline (NaOH) and alkaline/peroxide (NaOH/H2O2) were employed to treat hemp hurds to improve their miscibility with poly(lactic acid) (PLA) for the formation of biocomposites. The effects of reinforcement content (5, 10, and 15 wt. %), chemical treatments (purely alkaline vs. alkaline/peroxide) and treatment cycles (1 and 3 cycles) on the mechanical and thermal properties of the biocomposites were investigated. The biocomposites of treated hemp hurd powder exhibited enhanced thermal stability in the temperature range commonly used to process PLA (130–180 °C). The biocomposites containing 15 wt. % hemp hurd powder prepared using a single-cycle alkaline/peroxide treatment (PLA/15APHH1) exhibited a Young’s modulus of 2674 MPa, which is 70% higher than that of neat PLA and 9.3% higher than that of biocomposites comprised of PLA containing the same wt. % of untreated hemp hurd powder (PLA/15UHH). Furthermore, the tensile strength of the PLA/15APHH1 biocomposite was found to be 62.6 MPa, which was 6.5% lower than that of neat PLA and 23% higher than that of the PLA/15UHH sample. The results suggest that the fabricated PLA/hemp hurd powder biocomposites have great potential to be utilized in green and sustainable packaging applications.

The goal of this study is to improve the integration of implanted microdevices with tissue in the central nervous system (CNS). The long-term utility of neuroprosthetic devices implanted in the CNS is affected by the formation of a scar by resident glial cells (astrocytes and microglia), limiting the viability and functional stability of the devices. Reduction in the proliferation of glial cells is expected to enhance the biocompatibility of devices. We demonstrate the modification of polyimide-insulated microelectrodes with a bioactive peptide KHIFSDDSSE. Microelectrode wires were functionalized with (3-aminopropyl) triethoxy silane (APTES); the peptide was then covalently bonded to the APTES. The soluble peptide was tested in 2D mixed cultures of astrocytes and microglia, and reduced the proliferation of both cell types. The interactions of glial cells with the peptide-modified wires was then examined in 3D cell-laden hydrogels by immunofluorescence microscopy. As expected for uncoated wires, the microglia were first attracted to the wire (7 days) followed by astrocyte recruitment and hypertrophy (14 days). For the peptide-treated wires, astrocytes coated the wires directly (24 h), and formed a thin, stable coating without evidence of hypertrophy, and the attraction of microglia to the wire was significantly reduced. The results suggest a mechanism to improve tissue integration by promoting uniform coating of astrocytes on a foreign body while lessening the reactive response of microglia. We conclude that the bioactive peptide KHIFSDDSSE may be effective in improving the biocompatibility of neural interfaces by both reducing acute glial reactivity and generating stable integration with tissue. Statement of significance The peptide KHIFSDDSSE has previously been shown in vitro to both reduce the proliferation of astrocytes, and to increase the adhesion of astrocyte to glass substrates. Here, we demonstrate a method to apply uniform coatings of peptides to microwires, which could readily be generalized to other peptides and surfaces. We then show that when peptide-modified wires are inserted into 3D cell-laden hydrogels, the normal cellular reaction (microglial activation followed by astrocyte recruitment and hypertrophy) does not occur, rather astrocytes are attracted directly to the surface of the wire, forming a relatively thin and uniform coating. This suggests a method to improve tissue integration of implanted devices to reduce glial scarring and ultimately reduce failure of neural interfaces.

With the recent rise of organic electronics, bioelectronics, and transient devices, polymer thin films are finding prominence as substrates, functional layers and diffusion barriers. While some of these applications require degradable polymers, others necessitate materials with high stability and resistance to degradation during operation. Due to their minuscule thickness and mass, it is challenging to characterize the degradation and stability of thin films using existing techniques developed mainly for bulk materials. We introduce here a diffraction-based degradation sensor that can monitor the physical changes that take place as polymer chains are removed during the surface degradation of a polymer film without requiring expensive equipment and extensive sample preparation. To assess the degradation of a polymer film, the surface of the polymer is first patterned with a diffraction grating. This grating forms the key component of the degradation sensor, which also includes a laser and a photodetector to monitor diffraction efficiency as a function of time. When the patterned polymer surface degrades, the diffraction efficiency decreases. As validation, we use this approach to observe both enzymatic degradation of polyhydroxybutyrate films, and dissolution stability of silk. We demonstrate that the degradation sensor can monitor, with high reliability, the degradation of samples with minute mass changes, enabling qualitative and quantitative comparisons in different sample types and/or exposed to various degradation environments.

New N-aryl-2-{3-[ω-(4-bromophenoxy)alkyl]-2,6-dioxo-3,6-dihydropyrimidin-1(2H)-yl}acetamides have been obtained from 1-[ω-(4-bromophenoxy)alkyl]uracil and 2-chloro-N-(4-phenoxyphenyl)acetamide derivatives. Investigation of their antiviral properties against human cytomegalovirus revealed that the representative with dodecane-1,12-diyl linker exhibited powerful virus inhibitory activity in vitro.

Graphical abstract, 1-[tert-Butyl(diphenyl)silyl]pyrrol-3-ylboronic acid was obtained from pyrrole in three steps. Its Suzuki–Miyaura cross-coupling with functionalized pyridinyl and pyrimidinyl bromides afforded new promising 3-hetaryl-1H-pyrroles.

Carbocyclic nucleosides have long played a role in antiviral, antiparasitic, and antibacterial therapies. Recent results from our laboratories from two structurally related scaffolds have shown promising activity against both Mycobacterium tuberculosis and several parasitic strains. As a result, a small structure activity relationship study was designed to further probe their activity and potential. Their synthesis and the results of the subsequent biological activity are reported herein.

A general method is described for the coupling of (hetero)aryl bromides with O-alkyl sulfamate esters. The protocol relies on catalytic amounts of nickel and photoexcitable iridium complexes and proceeds under visible light at ambient temperature. This technology engages a broad range of simple and complex O-alkyl sulfamate ester substrates under mild conditions. Furthermore, it is possible to avoid undesirable N-alkylation, which was found to plague palladium-based protocols for N-arylation of O-alkyl sulfamate esters. These investigations represent the first use of sulfamate esters as nucleophiles in transition metal-catalyzed C–N coupling processes.

Alcohol-anchored sulfamate esters guide the alkylation of tertiary and secondary aliphatic C(3)–H bonds. The transformation proceeds directly from N–H bonds with a catalytic oxidant, a contrast to prior methods which have required pre-oxidation of the reactive nitrogen center, or employed stoichiometric amounts of strong oxidants to obtain the sulfamyl radical. These sulfamyl radicals template otherwise rare 1,6-hydrogen-atom transfer (HAT) processes via seven-membered ring transition states to enable C(3)–H functionalization during Giese reactions.

Heterologous production of extracellular polyhydroxybutyrate (PHB) depolymerases (PhaZs) has been of interest for over 30 years, but implementation is sometimes difficult and can limit the scope of research. With the constant development of tools to improve recombinant protein production inEscherichia coli, we propose a method that takes characteristics of PhaZs from different bacterial strains into account. Recombinant His-tagged versions of PhaZs (rPhaZ) fromComamonas testosteroni31A,Cupriavidussp.,Marinobacter algicolaDG893,Pseudomonas stutzeri, andRalstoniasp. were successfully produced with varying expression, solubility, and purity levels. PhaZs fromC. testosteroniandP. stutzeriwere more amenable to heterologous expression in all aspects; however, strategies were developed to circumvent low expression and purity for the other PhaZs. Degradation activity of the rPhaZs was compared using a simple PHB plate-based method, adapted to test for various pH and temperatures. rPhaZ fromM. algicolapresented the highest activity at 15 °C, and rPhaZs fromCupriavidussp. andRalstoniasp. had the highest activity at pH 5.4. The methods proposed herein can be used to test the production of soluble recombinant PhaZs, and to perform preliminary evaluation for applications that require PHB degradation.

A series of 1,6-bis[(benzyloxy)methyl]uracil derivatives combining structural features of both diphenyl ether and pyridone types of NNRTIs were synthesized. Target compounds were found to inhibit HIV-1 reverse transcriptase at micro- and submicromolar levels of concentrations and exhibited anti-HIV-1 activity in MT-4 cell culture, demonstrating resistance profile similar to first generation NNRTIs. The synthesized compounds also showed profound activity against influenza virus (H1N1) in MDCK cell culture without detectable cytotoxicity. The lead compound of this assay appeared to exceed rimantadine, amantadine, ribavirin and oseltamivir carboxylate in activity. The mechanism of action of 1,6-bis[(benzyloxy)methyl]uracils against influenza virus is currently under investigation.

Nonlethal exposure to ionizing radiation (IR) is a public concern due to its known carcinogenic effects. Although latency periods for IR-induced neoplasms are relatively long, the ability to detect cancer as early as possible is highly advantageous for effective therapeutic intervention. Therefore, we hypothesized that metabolites in the urine from mice exposed to total body radiation (TBI) would predict for the presence of cancer before a palpable mass was detected. In this study, we exposed mice to 0 or 5.4 Gy TBI, collected urine samples periodically over 1 year, and assayed urine metabolites by using mass spectrometry. Longitudinal data analysis within the first year post-TBI revealed that cancers, including hematopoietic, solid, and benign neoplasms, could be distinguished by unique urinary signatures as early as 3 months post-TBI. Furthermore, a distinction among different types of malignancies could be clearly delineated as early as 3 months post-TBI for hematopoietic neoplasms, 6 months for solid neoplasms, and by 1 year for benign neoplasms. Moreover, the feature profile for radiation-exposed mice 6 months post-TBI was found to be similar to nonirradiated control mice at 18 months, suggesting that TBI accelerates aging. These results demonstrate that urine feature profiles following TBI can identify cancers in mice prior to macroscopic detection, with important implications for the early diagnosis and treatment. Cancer Res; 76(6); 1569–77. ©2016 AACR.

New well-soluble in 10% DMSO phosphonate derivatives of substituted benzophenone have been synthesized using different methods. Preliminary computer modeling of proposed structures in the reverse transcriptase HIV-1 hydrophobic pocket suggested these molecules as potential non-nucleoside inhibitors of this enzyme.

Opportunities for developing end-of-life sensors for fire resistant fabrics are explored using reduced graphene oxide coatings on textiles. Fire resistant fabrics are known to experience significant losses in performance over time. Large reductions in mechanical properties have also been recorded when these fabrics were subjected to accelerated aging conditions simulating the use in service. In addition, the fabric loss in performance may exceed the safety requirement threshold before any sign of damage is visible to the naked eye. Electrically conductive coatings and tracks were prepared on an m-aramid woven fabric using graphene oxide that was further reduced. The preparation technique allowed wrapping the individual aramid fibers with rGO sheets. No significant change in sheet resistance was recorded after up to 120h of immersion of the rGO-coated fabric specimens in water. An increase in resistance after 10 accelerated washing cycles was measured on the rGO-coated specimens prepared with 5 coating cycles while no significant effect was detected for specimens prepared with 10 and 15 coating cycles. Under abrasion exposure, the electrical resistance of rGO tracks increased gradually until 150 cycles, after which the conductivity dropped abruptly. These results show the potential of reduced graphene oxide applied as a coating on m-aramid fabrics to prepare end-of-life sensors for fire resistant fabrics.

Here we report the synthesis and biological activity of new 5&prime, norcarbocyclic derivatives of bicyclic pyrrolo- and furano[2,3-d]pyrimidines with different substituents in the heterocyclic ring. Lead compound 3i, containing 6-pentylphenyl substituent, displays inhibitory activity with respect to a number of tumor cells with a moderate selectivity index value. Compound 3i induces cell death by the apoptosis pathway with the dissipation of mitochondrial potential.

A series of novel 5&prime, norcarbocyclic derivatives of 5-alkoxymethyl or 5-alkyltriazolyl-methyl uracil were synthesized and the activity of the compounds evaluated against both Gram-positive and Gram-negative bacteria. The growth of Mycobacterium smegmatis was completely inhibited by the most active compounds at a MIC99 of 67 &mu, g/mL (mc2155) and a MIC99 of 6.7&ndash, 67 &mu, g/mL (VKPM Ac 1339). Several compounds also showed the ability to inhibit the growth of attenuated strains of Mycobacterium tuberculosis ATCC 25177 (MIC99 28&ndash, 61 &mu, g/mL) and Mycobacterium bovis ATCC 35737 (MIC99 50&ndash, 60 &mu, g/mL), as well as two virulent strains of M. tuberculosis, a laboratory strain H37Rv (MIC99 20&ndash, 50 &mu, g/mL) and a clinical strain with multiple drug resistance MS-115 (MIC99 20&ndash, g/mL). Transmission electron microscopy (TEM) evaluation of M. tuberculosis H37Rv bacterial cells treated with one of the compounds demonstrated destruction of the bacterial cell wall, suggesting that the mechanism of action for these compounds may be related to their interactions with bacteria cell walls.

xiii Preface xiv Rationale xiv Dissertation organization xiv Authors’ roles xiv Chapter 1. General Introduction 1 Malnutrition 1 The problem of malnutrition 1 Potential solutions to malnutrition 1 Biofortification 3 Iron deficiency and improvements in dietary iron 4 Iron deficiency and absorption 4 Inhibitors and enhancers of iron bioavailability 5 Iron forticants 6 Biofortification of iron 8 Hemoglobin 9 Plant hemoglobin 9 Protein deficiency and seed storage proteins in maize 11 Protein deficiency 11 Dietary requirements for protein 12

The biodegradation of polyhydroxybutyrate (PHB) has been broadly investigated, but studies typically focus on a single strain or enzyme and little attention has been paid to comparing the interaction of different PHB depolymerase (PhaZ)-producing strains with this biopolymer. In this work, we selected nine bacterial strains-five with demonstrated and four with predicted PhaZ activity-to compare their effectiveness at degrading PHB film provided as sole carbon source. Each of the strains with demonstrated activity were able to use the PHB film (maximum mass losses ranging from 12% after 2 days for Paucimonas lemoignei to 90% after 4 days for Cupriavidus sp.), and to a lower extent Marinobacter algicola DG893 (with a predicted PhaZ) achieved PHB film mass loss of 11% after 2 weeks of exposure. Among the strains with proven PhaZ activity, Ralstonia sp. showed the highest specific activity since less biomass was required to degrade the polymer in comparison to the other strains. In the case of Ralstonia sp., PHB continued to be degraded at pH values as low as pH 3.3-3.7. In addition, analysis of the extracellular fractions of the strains with demonstrated activity showed that Comamonas testosteroni, Cupriavidus sp., and Ralstonia sp. readily degraded both PHB film and PHB particles in agar suspensions. This study highlights that whole cell cultures and enzymatic (extracellular) fractions display different levels of activity, an important factor in the development of PHB-based applications and in understanding the fate of PHB and other PHAs released in the environment. Furthermore, predictions of PhaZ functionality from genome sequencing analyses remain to be validated by experimental results; PHB-degrading ability could not be proven for three of four investigated species predicted by the polyhydroxyalkanoates (PHA) depolymerase engineering database.

A series of 1-[(bromophenoxy)alkyl]uracil–coumarin conjugates has been obtained through the preparation of starting 1-[(bromophenoxy)alkyl]uracil derivatives, followed by their treatment with 7-(ω-bromoalkoxy)-4-methyl-2H-chromen-2-ones. Two of the synthesized uracil–coumarin conjugates demonstrated a pronounced inhibitory activity against HCMV and VZV replication in vitro.

Graphical abstract, The need for novel therapeutic options to fight herpesvirus infections still persists. Herein we report the design, synthesis and antiviral evaluation of a new family of non-nucleoside antivirals, derived from 1-[ω-(4-bromophenoxy)alkyl]uracil derivatives – previously reported inhibitors of human cytomegalovirus (HCMV). Introduction of the N-(4-phenoxyphenyl)acetamide side chain at N3 increased their potency and widened activity spectrum. The most active compounds in the series exhibit submicromolar activity against different viral strains of HCMV and varicella zoster virus (VZV) replication in HEL cell cultures. Inactivity against other DNA and RNA viruses, including herpes simplex virus 1/2, points to a novel mechanism of antiviral action.

5′-Norcarbocyclic analogues of furano[2,3-d]pyrimidine nucleosides as well as 5-bromo and 5-iodouracil derivatives were synthesized to evaluate their potential antitumor activity. The halogenated derivatives display no cytotoxicity with respect to all tested cells: KB-3-1 (human epidermoid carcinoma), HeLa (human cervical epithelioid carcinoma), HuTu-80 (human duodenal cancer), B16 (mouse melanoma), and MDCK (normal epithelial). The cytotoxicity of the non-halogenated furano[2,3-d]pyrimidine derivatives increases with the lengthening of the alkyl chain of the substituent from 45 to 60 μm for octyl to from 3 to 10 μm for dodecyl.

Nitric oxide synthases (NOS) are important mediators of progrowth signaling in tumor cells, as they regulate angiogenesis, immune response, and immune-mediated wound healing. Ionizing radiation (IR) is also an immune modulator and inducer of wound response. We hypothesized that radiation therapeutic efficacy could be improved by targeting NOS following tumor irradiation. Herein, we show enhanced radiation-induced (10 Gy) tumor growth delay in a syngeneic model (C3H) but not immunosuppressed (Nu/Nu) squamous cell carcinoma tumor-bearing mice treated post-IR with the constitutive NOS inhibitor NG-nitro-l-arginine methyl ester (L-NAME). These results suggest a requirement of T cells for improved radiation tumor response. In support of this observation, tumor irradiation induced a rapid increase in the immunosuppressive Th2 cytokine IL10, which was abated by post-IR administration of L-NAME. In vivo suppression of IL10 using an antisense IL10 morpholino also extended the tumor growth delay induced by radiation in a manner similar to L-NAME. Further examination of this mechanism in cultured Jurkat T cells revealed L-NAME suppression of IR-induced IL10 expression, which reaccumulated in the presence of exogenous NO donor. In addition to L-NAME, the guanylyl cyclase inhibitors ODQ and thrombospondin-1 also abated IR-induced IL10 expression in Jurkat T cells and ANA-1 macrophages, which further suggests that the immunosuppressive effects involve eNOS. Moreover, cytotoxic Th1 cytokines, including IL2, IL12p40, and IFNγ, as well as activated CD8+ T cells were elevated in tumors receiving post-IR L-NAME. Together, these results suggest that post-IR NOS inhibition improves radiation tumor response via Th1 immune polarization within the tumor microenvironment. Cancer Res; 75(14); 2788–99. ©2015 AACR.

Objective The nitroxide compound TEMPOL (4-hydroxy-2,2,6,6-tetramethylpiperidine- N -oxyl radical) has been shown to prevent obesity-induced changes in adipokines in cell and animal systems. In this study we investigated whether supplementation with TEMPOL inhibits inflammation and atherosclerosis in apoE −/− mice fed a high fat diet (HFD). Methods ApoE −/− mice were fed for 12 weeks on standard chow diet or a high-fat diet. Half the mice were supplemented with 10 mg/g TEMPOL in their food. Plasma samples were analysed for triglycerides, cholesterol, low- and high-density lipoprotein cholesterol, inflammatory cytokines and markers (interleukin-6, IL-6; monocyte-chemotactic protein, MCP-1; myeloperoxidase, MPO; serum amyloid A, SAA; adiponectin; leptin). Plaques in the aortic sinus were analysed for area, and content of collagen, lipid, macrophages and smooth muscle cells. Results High fat feeding resulted in marked increases in body mass and plasma lipid levels. Dietary TEMPOL decreased both parameters. In the high-fat-fed mice significant elevations in plasma lipid levels and the inflammatory markers IL-6, MCP-1, MPO, SAA were detected, along with an increase in leptin and a decrease in adiponectin. TEMPOL supplementation reversed these effects. When compared to HFD-fed mice, TEMPOL supplementation increased plaque collagen content, decreased lipid content and increased macrophage numbers. Conclusions These data indicate that in a well-established model of obesity-associated hyperlipidaemia and atherosclerosis, TEMPOL had a significant impact on body mass, atherosclerosis, hyperlipidaemia and inflammation. TEMPOL may therefore be of value in suppressing obesity, metabolic disorders and increasing atherosclerotic plaque stability.

In order to identify new antiretroviral agents, a series of novel uracil derivatives have been synthesized. Optimized conditions for coupling of Weinreb amides with aromatic Grignard reagents allow the convenient preparation of key benzophenone intermediates in high yields and purities. The use of a modified silyl Hilbert–Johnson reaction affords the target compounds under mild conditions.