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1.
ACS Appl Mater Interfaces ; 15(27): 32916-32925, 2023 Jul 12.
Artigo em Inglês | MEDLINE | ID: mdl-37384826

RESUMO

From drug delivery to ballistic impact, the ability to control or mitigate the puncture of a fast-moving projectile through a material is critical. While puncture is a common occurrence, which can span many orders of magnitude in the size, speed, and energy of the projectile, there remains a need to connect our understanding of the perforation resistance of materials at the nano- and microscale to the actual behavior at the macroscale that is relevant for engineering applications. In this article, we address this challenge by combining a new dimensional analysis scheme with experimental data from micro- and macroscale impact tests to develop a relationship that connects the size-scale effects and materials properties during high-speed puncture events. By relating the minimum perforation velocity to fundamental material properties and geometric test conditions, we provide new insights and establish an alternative methodology for evaluating the performance of materials that is independent of the impact energy or the specific projectile puncture experiment type. Finally, we demonstrate the utility of this approach by assessing the relevance of novel materials, such as nanocomposites and graphene for real-world impact applications.

2.
Molecules ; 28(12)2023 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-37375183

RESUMO

Pleuromutilins are a group of antibiotics derived from the naturally occurring compound. The recent approval of lefamulin for both intravenous and oral doses in humans to treat community-acquired bacterial pneumonia has prompted investigations in modifying the structure to broaden the antibacterial spectrum, enhance the activity, and improve the pharmacokinetic properties. AN11251 is a C(14)-functionalized pleuromutilin with a boron-containing heterocycle substructure. It was demonstrated to be an anti-Wolbachia agent with therapeutic potential for Onchocerciasis and lymphatic filariasis. Here, the in vitro and in vivo PK parameters of AN11251 were measured including PPB, intrinsic clearance, half-life, systemic clearance, and volume of distribution. The results indicate that the benzoxaborole-modified pleuromutilin possesses good ADME and PK properties. AN11251 has potent activities against the Gram-positive bacterial pathogens tested, including various drug-resistant strains, and against the slow-growing mycobacterial species. Finally, we employed PK/PD modeling to predict the human dose for treatment of disease caused by Wolbachia, Gram-positive bacteria, or Mycobacterium tuberculosis, which might facilitate the further development of AN11251.


Assuntos
Diterpenos , Oncocercose , Compostos Policíclicos , Humanos , Antibacterianos/química , Boro , Diterpenos/química , Compostos Policíclicos/farmacologia , Oncocercose/tratamento farmacológico , Bactérias , Bactérias Gram-Positivas , Testes de Sensibilidade Microbiana , Pleuromutilinas
3.
Methods Enzymol ; 679: 275-293, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36682865

RESUMO

Aminoacyl-tRNA synthetases (aaRSs) catalyze aminoacylation of tRNAs to produce aminoacyl-tRNAs for protein synthesis. Bacterial aaRSs have distinctive features, play an essential role in channeling amino acids into biomolecular assembly, and are vulnerable to inhibition by small molecules. The aaRSs continue to be targets for potential antibacterial drug development. The first step of aaRS reaction is the activation of amino acid by hydrolyzing ATP to form an acyladenylate intermediate with the concomitant release of pyrophosphate. None-radioactive assays usually measure the rate of ATP consumption or phosphate generation, offering advantages in high-throughput drug screening. These simple aaRS enzyme assays can be adapted to study the mode of inhibition of natural or synthetic aaRS inhibitors. Taking phenylalanyl-tRNA synthetase (PheRS) of Mycobacterium tuberculosis (Mtb) as an example, we describe a process for identification and characterization of Mtb PheRS inhibitor.


Assuntos
Aminoacil-tRNA Sintetases , Mycobacterium tuberculosis , Fenilalanina-tRNA Ligase , Mycobacterium tuberculosis/metabolismo , Aminoacil-tRNA Sintetases/genética , RNA de Transferência/metabolismo , Aminoácidos , Trifosfato de Adenosina
4.
ACS Infect Dis ; 8(10): 2019-2027, 2022 10 14.
Artigo em Inglês | MEDLINE | ID: mdl-36048501

RESUMO

ATP provides energy in the biosynthesis of cellular metabolites as well as regulates protein functions through phosphorylation. Many ATP-dependent enzymes are antibacterial and anticancer targets including human kinases acted on by most of the successful drugs. In search of new chemotherapeutics for tuberculosis (TB), we screened repurposing compounds against the essential glutamine synthase (GlnA1) of Mycobacterium tuberculosis (Mtb) and identified linsitinib, a clinical-stage drug originally targeting kinase IGF1R/IR as a potent GlnA1 inhibitor. Linsitinib has direct antimycobacterial activity. Biochemical, molecular modeling, and target engagement analyses revealed the inhibition is ATP-competitive and specific in Mtb. Linsitinib also improves autophagy flux in both Mtb-infected and uninfected THP1 macrophages, as demonstrated by the decreased p-mTOR and p62 and the increased lipid-bound LC3B-II and autophagosome forming puncta. Linsitinib-mediated autophagy reduces intracellular growth of wild-type and isoniazid-resistant Mtb alone or in combination with bedaquiline. We have demonstrated that an IGF-IR/IR inhibitor can potentially be used to treat TB. Our study reinforces the concept of targeting ATP-dependent enzymes for novel anti-TB therapy.


Assuntos
Mycobacterium tuberculosis , Tuberculose , Trifosfato de Adenosina/metabolismo , Antibacterianos/metabolismo , Glutamina/metabolismo , Humanos , Imidazóis , Isoniazida , Lipídeos , Mycobacterium tuberculosis/metabolismo , Inibidores de Proteínas Quinases , Pirazinas , Receptor IGF Tipo 1/metabolismo , Serina-Treonina Quinases TOR/metabolismo , Tuberculose/tratamento farmacológico , Tuberculose/microbiologia
5.
Bioengineering (Basel) ; 9(8)2022 Jul 24.
Artigo em Inglês | MEDLINE | ID: mdl-35892747

RESUMO

Computational modeling of the whole human heart has become a valuable tool to evaluate medical devices such as leadless pacemakers, annuloplasty rings and left ventricular assist devices, since it is often difficult to replicate the complex dynamic interactions between the device and human heart in bench-top and animal tests. The Dassault Systèmes Living Heart Human Model (LHHM) is a finite-element model of whole-human-heart electromechanics that has input parameters that were previously calibrated to generate physiological responses in a healthy heart beating at 60 beat/min (resting state). This study demonstrates that, by adjusting only six physiologically meaningful parameters, the LHHM can be recalibrated to generate physiological responses in a healthy heart beating at heart rates ranging from 90−160 beat/min. These parameters are as follows: the sinoatrial node firing period decreases from 0.67 s at 90 bpm to 0.38 s at 160 bpm, atrioventricular delay decreases from 0.122 s at 90 bpm to 0.057 s at 160 bpm, preload increases 3-fold from 90 bpm to 160 bpm, body resistance at 160 bpm is 80% of that at 90 bpm, arterial stiffness at 160 bpm is 3.9 times that at 90 bpm, and a parameter relating myofiber twitch force duration and sarcomere length decreases from 238 ms/mm at 90 bpm to 175 ms/mm at 160 bpm. In addition, this study demonstrates the feasibility of using the LHHM to conduct clinical investigations in AV delay optimization and hemodynamic differences between pacing and exercise. AV delays in the ranges of 40 ms to 250 ms were simulated and stroke volume and systolic blood pressure showed clear peaks at 120 ms for 90 bpm. For a heart during exercise, the increase in cardiac output continues to 160 bpm. However, for a heart during pacing, those physiological parameter adjustments are removed that are related to changes in body oxygen requirements (preload, arterial stiffness and body resistance). Consequently, cardiac output increases initially with heart rate; as the heart rate goes up (>100 bpm), the increasing rate of cardiac output slows down and approaches a plateau.

6.
ACS Chem Biol ; 17(1): 39-53, 2022 01 21.
Artigo em Inglês | MEDLINE | ID: mdl-34908399

RESUMO

Indolmycin (IND) is a microbial natural product that selectively inhibits bacterial tryptophanyl-tRNA synthetase (TrpRS). The tryptophan biosynthesis pathway was recently shown to be an important target for developing new antibacterial agents against Mycobacterium tuberculosis (Mtb). We investigated the antibacterial activity of IND against several mycobacterial model strains. A TrpRS biochemical assay was developed to analyze a library of synthetic IND analogues. The 4″-methylated IND compound, Y-13, showed improved anti-Mtb activity with a minimum inhibitory concentration (MIC) of 1.88 µM (∼0.5 µg/mL). The MIC increased significantly when overexpression of TrpRS was induced in the genetically engineered surrogate M. bovis BCG. The cocrystal structure of Mtb TrpRS complexed with IND and ATP has revealed that the amino acid pocket is in a state between the open form of apo protein and the closed complex with the reaction intermediate. In whole-cell-based experiments, we studied the combination effect of Y-13 paired with different antibacterial agents. We evaluated the killing kinetics, the frequency of resistance to INDs, and the mode of resistance of IND-resistant mycobacteria by genome sequencing. The synergistic interaction of Y-13 with the TrpE allosteric inhibitor, indole propionic acid, suggests that prospective IND analogues could shut down tryptophan biosynthesis and protein biosynthesis in pathogens, leading to a new class of antibiotics. Finally, we discuss a strategy to expand the genome mining of antibiotic-producing microbes specifically for antimycobacterial development.


Assuntos
Antibacterianos/farmacologia , Produtos Biológicos/farmacologia , Mycobacterium bovis/efeitos dos fármacos , Antibacterianos/química , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Produtos Biológicos/química , Clonagem Molecular , Escherichia coli , Regulação Bacteriana da Expressão Gênica/efeitos dos fármacos , Genes Bacterianos , Indóis/química , Indóis/farmacologia , Estrutura Molecular , Mutação
7.
Soft Matter ; 18(2): 256-261, 2022 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-34931215

RESUMO

Toughness in an entangled polymer network is typically controlled by the number of load-bearing topological constraints per unit volume. In this work, we demonstrate a new paradigm for controlling toughness at high deformation rates in a polymer-grafted nanoparticle composite system where the entanglement density increases with the molecular mass of the graft. An unexpected peak in the toughness is observed right before the system reaches full entanglement that cannot be described through the entanglement concept alone. Quasi-elastic neutron scattering reveals enhanced segmental fluctuations of the grafts on the picosecond time scale, which propagate out to nanoparticle fluctuations on the time scale 100s of seconds as evidenced by X-ray photon correlation spectroscopy. This surprising multi-scale dissipation process suggests a nanoparticle jamming-unjamming transition. The realization that segmental dynamics can be coupled with the entanglement concept for enhanced toughness at high rates of deformation is a novel insight with relevance to the design of composite materials.

8.
J Biol Chem ; 296: 100257, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33837735

RESUMO

Mycobacterium tuberculosis (Mtb) remains the deadliest pathogenic bacteria worldwide. The search for new antibiotics to treat drug-sensitive as well as drug-resistant tuberculosis has become a priority. The essential enzyme phenylalanyl-tRNA synthetase (PheRS) is an antibacterial drug target because of the large differences between bacterial and human PheRS counterparts. In a high-throughput screening of 2148 bioactive compounds, PF-3845, which is a known inhibitor of human fatty acid amide hydrolase, was identified inhibiting Mtb PheRS at Ki ∼ 0.73 ± 0.06 µM. The inhibition mechanism was studied with enzyme kinetics, protein structural modeling, and crystallography, in comparison to a PheRS inhibitor of the noted phenyl-thiazolylurea-sulfonamide class. The 2.3-Å crystal structure of Mtb PheRS in complex with PF-3845 revealed its novel binding mode, in which a trifluoromethyl-pyridinylphenyl group occupies the phenylalanine pocket, whereas a piperidine-piperazine urea group binds into the ATP pocket through an interaction network enforced by a sulfate ion. It represents the first non-nucleoside bisubstrate competitive inhibitor of bacterial PheRS. PF-3845 inhibits the in vitro growth of Mtb H37Rv at ∼24 µM, and the potency of PF-3845 increased against an engineered strain Mtb pheS-FDAS, suggesting on target activity in mycobacterial whole cells. PF-3845 does not inhibit human cytoplasmic or mitochondrial PheRS in biochemical assay, which can be explained from the crystal structures. Further medicinal chemistry efforts focused on the piperidine-piperazine urea moiety may result in the identification of a selective antibacterial lead compound.


Assuntos
Mycobacterium tuberculosis/enzimologia , Fenilalanina-tRNA Ligase/ultraestrutura , Conformação Proteica , Tuberculose Resistente a Múltiplos Medicamentos/tratamento farmacológico , Amidoidrolases/antagonistas & inibidores , Amidoidrolases/química , Sequência de Aminoácidos/genética , Antibacterianos/química , Sítios de Ligação/efeitos dos fármacos , Cristalografia por Raios X , Humanos , Cinética , Mycobacterium tuberculosis/efeitos dos fármacos , Mycobacterium tuberculosis/patogenicidade , Fenilalanina-tRNA Ligase/antagonistas & inibidores , Fenilalanina-tRNA Ligase/química , Piperidinas/química , Piperidinas/farmacologia , Piridinas/química , Piridinas/farmacologia , Tuberculose Resistente a Múltiplos Medicamentos/enzimologia , Tuberculose Resistente a Múltiplos Medicamentos/genética
9.
J Biol Chem ; 2021 Jan 04.
Artigo em Inglês | MEDLINE | ID: mdl-33397709

RESUMO

Mycobacteria tuberculosis (Mtb) remains the deadliest pathogenic bacteria worldwide. The search for new antibiotics to treat drug-sensitive as well as drug-resistant tuberculosis has become a priority. The essential enzyme phenylalanyl-tRNA synthetase (PheRS) is an antibacterial drug target because of the large differences between bacterial and human PheRS counterparts. In a high-throughput screening of 2148 bioactive compounds, PF-3845, which is a known inhibitor of human fatty acid amide hydrolase (FAAH), was identified inhibiting Mtb PheRS at Ki ~0.73 ± 0.06 µM. The inhibition mechanism was studied with enzyme kinetics, protein structural modelling and crystallography, in comparison to a PheRS inhibitor of the noted phenyl-thiazolylurea-sulfonamide class. The 2.3-Å crystal structure of Mtb PheRS in complex with PF-3845 revealed its novel binding mode, in which a trifluoromethyl-pyridinylphenyl group occupies the Phe pocket while a piperidine-piperazine urea group binds into the ATP pocket through an interaction network enforced by a sulfate ion. It represents the first non-nucleoside bi-substrate competitive inhibitor of bacterial PheRS. PF-3845 inhibits the in vitro growth of Mtb H37Rv at ~24 µM, and the potency of PF-3845 increased against Mtb pheS-FDAS, suggesting on target activity in mycobacterial whole cells.  PF-3845 does not inhibit human cytoplasmic or mitochondrial PheRS in biochemical assay, which can be explained from the crystal structures. Further medicinal chemistry efforts focused on the piperidine-piperazine urea moiety may result in the identification of a selective antibacterial lead compound.

10.
Soft Matter ; 16(16): 3886-3890, 2020 Apr 29.
Artigo em Inglês | MEDLINE | ID: mdl-32285897

RESUMO

The dynamic impact between a particle and a planar material is important in many high impact events, and there is a growing need to characterize the mechanical properties of light-weight polymeric materials at dynamic loading conditions. Here, a laser-induced projectile impact test (LIPIT) is employed to investigate the ballistic limit (V0) and materials properties at impact velocities ranging from 40 m s-1 to 70 m s-1. An analytical expression describing the various energy dissipation mechanisms is established to estimate the yield stress and elasticity for polycarbonate thin films. This measurement approach demonstrates the utility of using low sample mass for discovery of materials for impact mitigation, as well as high-throughput mechanical characterization at dynamic loading rates.

11.
Stud Health Technol Inform ; 264: 1065-1069, 2019 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-31438088

RESUMO

Social media presents a rich opportunity to gather health information with limited intervention through the analysis of completely unstructured and unlabeled microposts. We sought to estimate the health-related quality of life (HRQOL) of Twitter users using automated semantic processing methods. We collected tweets from 878 Twitter users recruited through online solicitation and in-person contact with patients. All participants completed the four-item Centers for Disease Control Healthy Days Questionnaire at the time of enrollment and 30 days later to measure "ground truth" HRQOL. We used a combination of document frequency analysis, sentiment analysis, topic analysis, and concept mapping to extract features from tweets, which we then used to estimate dichotomized HRQOL ("high" vs. "low") using logistic regression. Binary HRQOL status was estimated with moderate performance (AUC = 0.64). This result indicates that free-range social media data only offers a window into HRQOL, but does not afford direct access to current health status.


Assuntos
Mídias Sociais , Coleta de Dados , Nível de Saúde , Humanos , Qualidade de Vida , Semântica
12.
Nat Commun ; 9(1): 3445, 2018 09 04.
Artigo em Inglês | MEDLINE | ID: mdl-30181560

RESUMO

Development of effective antimicrobial agents continues to be a great challenge, particularly due to the increasing resistance of superbugs and frequent hospital breakouts. There is an urgent need for more potent and safer antibiotics with novel scaffolds. As historically many commercial drugs were derived from natural products, discovery of antimicrobial agents from complex natural product structures still holds a great promise. Herein, we report the total synthesis of natural albomycins δ1 (1a), δ2 (1b), and ε (1c), which validates the structures of these peptidylnucleoside compounds and allows for synthetic access to bioactive albomycin analogs. The efficient synthesis of albomycins enables extensive evaluations of these natural products against model bacteria and clinical pathogens. Albomycin δ2 has the potential to be developed into an antibacterial drug to treat Streptococcus pneumoniae and Staphylococcus aureus infections.


Assuntos
Anti-Infecciosos/síntese química , Anti-Infecciosos/farmacologia , Ferricromo/análogos & derivados , Anti-Infecciosos/química , Técnicas de Química Sintética , Avaliação Pré-Clínica de Medicamentos/métodos , Ferricromo/química , Ferricromo/farmacologia , Humanos , Testes de Sensibilidade Microbiana , Estrutura Molecular , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/isolamento & purificação , Streptococcus pneumoniae/efeitos dos fármacos , Streptococcus pneumoniae/isolamento & purificação
13.
BMC Dev Biol ; 18(1): 7, 2018 03 27.
Artigo em Inglês | MEDLINE | ID: mdl-29587629

RESUMO

BACKGROUND: FK506-binding proteins (FKBPs) have become the subject of considerable interest in several fields, leading to the identification of several cellular and molecular pathways in which FKBPs impact prenatal development and pathogenesis of many human diseases. MAIN BODY: This analysis revealed differences between how mammalian and Drosophila FKBPs mechanisms function in relation to the immunosuppressant drugs, FK506 and rapamycin. Differences that could be used to design insect-specific pesticides. (1) Molecular phylogenetic analysis of FKBP family proteins revealed that the eight known Drosophila FKBPs share homology with the human FKBP12. This indicates a close evolutionary relationship, and possible origination from a common ancestor. (2) The known FKBPs contain FK domains, that is, a prolyl cis/trans isomerase (PPIase) domain that mediates immune suppression through inhibition of calcineurin. The dFKBP59, CG4735/Shutdown, CG1847, and CG5482 have a Tetratricopeptide receptor domain at the C-terminus, which regulates transcription and protein transportation. (3) FKBP51 and FKBP52 (dFKBP59), along with Cyclophilin 40 and protein phosphatase 5, function as Hsp90 immunophilin co-chaperones within steroid receptor-Hsp90 heterocomplexes. These immunophilins are potential drug targets in pathways associated with normal physiology and may be used to treat a variety of steroid-based diseases by targeting exocytic/endocytic cycling and vesicular trafficking. (4) By associating with presinilin, a critical component of the Notch signaling pathway, FKBP14 is a downstream effector of Notch activation at the membrane. Meanwhile, Shutdown associates with transposons in the PIWI-interacting RNA pathway, playing a crucial role in both germ cells and ovarian somas. Mutations in or silencing of dFKBPs lead to early embryonic lethality in Drosophila. Therefore, further understanding the mechanisms of FK506 and rapamycin binding to immunophilin FKBPs in endocrine, cardiovascular, and neurological function in both mammals and Drosophila would provide prospects in generating unique, insect specific therapeutics targeting the above cellular signaling pathways. CONCLUSION: This review will evaluate the functional roles of FKBP family proteins, and systematically summarize the similarities and differences between FKBP proteins in Drosophila and Mammals. Specific therapeutics targeting cellular signaling pathways will also be discussed.


Assuntos
Drosophila melanogaster/metabolismo , Mamíferos/metabolismo , Proteínas de Ligação a Tacrolimo/química , Proteínas de Ligação a Tacrolimo/metabolismo , Sequência de Aminoácidos , Animais , Evolução Molecular , Humanos , Inseticidas/toxicidade , Filogenia
14.
Cell Biosci ; 8: 24, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29599964

RESUMO

Macrophages are traditionally viewed as a key component of the immunity defense system. Recent studies have identified resident macrophages in multiple organs including the heart, in which the cells perform their crucial role on tissue repair after myocardial infarction (MI). The cardiac-specific macrophages interdigitate with cardiomyocytes particularly at the atrioventricular node region. The integrative communication between macrophage and cardiomyocytes can modulate the contractile function of the heart. Coordinated control of intracellular calcium signaling and intercellular electrical conduction via the syncytium network underlie the synchronized beating of the heart. In this review article, we introduce the concept the syncytium calcium signaling in the cardiomyocytes can modulate gene expression in the resident macrophages and their integration with the cardiomyocytes. The cardiac macrophages originate from bone marrow stem cells, migrate to local via vessel, and settle down as a naturalization process in heart. As the macrophages perform on regulating electrical conduction, and accomplish post MI non-scared completed regeneration or partial regeneration with fibrotic scar at different stage of postnatal development, we understand that multiple functions of cardiac macrophage should carry on with diverse linages. The naturalization process in heart of macrophages to the cardiomyocytes serves important roles to control of electrical signaling and calcium-dependent contractile function of the heart.

15.
World J Microbiol Biotechnol ; 33(4): 66, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-28260195

RESUMO

Modified nucleosides produced by Streptomyces and related actinomycetes are widely used in agriculture and medicine as antibacterial, antifungal, anticancer and antiviral agents. These specialized small-molecule metabolites are biosynthesized by complex enzymatic machineries encoded within gene clusters in the genome. The past decade has witnessed a burst of reports defining the key metabolic processes involved in the biosynthesis of several distinct families of nucleoside antibiotics. Furthermore, genome sequencing of various Streptomyces species has dramatically increased over recent years. Potential biosynthetic gene clusters for novel nucleoside antibiotics are now apparent by analysis of these genomes. Here we revisit strategies for production improvement of nucleoside antibiotics that have defined mechanisms of action, and are in clinical or agricultural use. We summarize the progress for genetically manipulating biosynthetic pathways for structural diversification of nucleoside antibiotics. Microorganism-based biosynthetic examples are provided and organized under genetic principles and metabolic engineering guidelines. We show perspectives on the future of combinatorial biosynthesis, and present a working model for discovery of novel nucleoside natural products in Streptomyces.


Assuntos
Antibacterianos/biossíntese , Engenharia Genética/métodos , Nucleosídeos/biossíntese , Streptomyces/genética , Antibacterianos/farmacologia , Proteínas de Bactérias/genética , Vias Biossintéticas , Descoberta de Drogas , Genoma Bacteriano , Testes de Sensibilidade Microbiana , Família Multigênica , Nucleosídeos/farmacologia , Streptomyces/metabolismo
16.
Langmuir ; 33(8): 1834-1844, 2017 02 28.
Artigo em Inglês | MEDLINE | ID: mdl-28142239

RESUMO

Polyelectrolyte complex (PEC) films made from oppositely charged polymer chains have applications as drug-delivery vehicles, separation membranes, and biocompatible coatings. Conventional layer-by-layer techniques for polyelectrolyte coatings are low-throughput and multistep processes that are quite slow for building films on the order of micrometers. In this work, PEC films are electrochemically deposited using a rapid one-pot method, yielding thick (1 µm) films within short experimental time scales (5 min). This rapid electrodeposition is achieved by exploiting the reduction of hydrogen peroxide at mild electrode potentials that avoid water electrolysis yet trigger the pH-responsive self-assembly of a PEC film composed of poly(acrylic) acid and poly(allylamine) HCl. In situ rheology using an electrochemical quartz crystal microbalance quantified the shear modulus-density product of the deposited layer to be on the order of 107 Pa g/cm3 at a frequency of 15 MHz, with a viscoelastic phase angle of approximately 50°. This electrodeposition scheme furthers the development of PEC coatings for more high-throughput applications, where a fast and efficient single-step approach would be desirable for obtaining coatings.

17.
J Am Chem Soc ; 138(29): 9053-6, 2016 07 27.
Artigo em Inglês | MEDLINE | ID: mdl-27396413

RESUMO

Two catalysts, an amine HCl salt and a bisthiourea, work in concert to enable the generation of oxocarbenium ions under mild conditions. The amine catalyst generates an iminium ion of sufficient electrophilicity to enable 1,2-attack by an alcohol. Catalyst turnover is achieved by amine elimination with concomitant formation of an oxocarbenium intermediate. The bisthiourea catalyst accelerates all of the steps of the reaction and controls the stereoselectivity via anion binding/ion pair formation. This new concept was applied to direct catalytic enantioselective oxa-Pictet-Spengler reactions of tryptophol with aldehydes.

18.
Comput Methods Programs Biomed ; 124: 67-75, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26614020

RESUMO

BACKGROUND AND OBJECTIVE: Probabilistic topic models provide an unsupervised method for analyzing unstructured text. These models discover semantically coherent combinations of words (topics) that could be integrated in a clinical automatic summarization system for primary care physicians performing chart review. However, the human interpretability of topics discovered from clinical reports is unknown. Our objective is to assess the coherence of topics and their ability to represent the contents of clinical reports from a primary care physician's point of view. METHODS: Three latent Dirichlet allocation models (50 topics, 100 topics, and 150 topics) were fit to a large collection of clinical reports. Topics were manually evaluated by primary care physicians and graduate students. Wilcoxon Signed-Rank Tests for Paired Samples were used to evaluate differences between different topic models, while differences in performance between students and primary care physicians (PCPs) were tested using Mann-Whitney U tests for each of the tasks. RESULTS: While the 150-topic model produced the best log likelihood, participants were most accurate at identifying words that did not belong in topics learned by the 100-topic model, suggesting that 100 topics provides better relative granularity of discovered semantic themes for the data set used in this study. Models were comparable in their ability to represent the contents of documents. Primary care physicians significantly outperformed students in both tasks. CONCLUSION: This work establishes a baseline of interpretability for topic models trained with clinical reports, and provides insights on the appropriateness of using topic models for informatics applications. Our results indicate that PCPs find discovered topics more coherent and representative of clinical reports relative to students, warranting further research into their use for automatic summarization.


Assuntos
Atitude do Pessoal de Saúde , Compreensão , Registros Eletrônicos de Saúde/classificação , Médicos de Atenção Primária/estatística & dados numéricos , Terminologia como Assunto , Vocabulário Controlado , Registros Eletrônicos de Saúde/organização & administração , Armazenamento e Recuperação da Informação/métodos , Uso Significativo/estatística & dados numéricos , Registro Médico Coordenado/métodos , Modelos Estatísticos , Processamento de Linguagem Natural , Semântica
19.
Appl Environ Microbiol ; 82(2): 467-77, 2016 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-26519385

RESUMO

Albomycin (ABM), also known as grisein, is a sulfur-containing metabolite produced by Streptomyces griseus ATCC 700974. Genes predicted to be involved in the biosynthesis of ABM and ABM-like molecules are found in the genomes of other actinomycetes. ABM has potent antibacterial activity, and as a result, many attempts have been made to develop ABM into a drug since the last century. Although the productivity of S. griseus can be increased with random mutagenesis methods, understanding of Streptomyces sulfur amino acid (SAA) metabolism, which supplies a precursor for ABM biosynthesis, could lead to improved and stable production. We previously characterized the gene cluster (abm) in the genome-sequenced S. griseus strain and proposed that the sulfur atom of ABM is derived from either cysteine (Cys) or homocysteine (Hcy). The gene product, AbmD, appears to be an important link between primary and secondary sulfur metabolic pathways. Here, we show that propargylglycine or iron supplementation in growth media increased ABM production by significantly changing the relative concentrations of intracellular Cys and Hcy. An SAA metabolic network of S. griseus was constructed. Pathways toward increasing Hcy were shown to positively impact ABM production. The abmD gene and five genes that increased the Hcy/Cys ratio were assembled downstream of hrdBp promoter sequences and integrated into the chromosome for overexpression. The ABM titer of one engineered strain, SCAK3, in a chemically defined medium was consistently improved to levels ∼400% of the wild type. Finally, we analyzed the production and growth of SCAK3 in shake flasks for further process development.


Assuntos
Aminoácidos Sulfúricos/metabolismo , Antibacterianos/biossíntese , Ferricromo/análogos & derivados , Streptomyces griseus/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Ferricromo/metabolismo , Família Multigênica , Streptomyces griseus/genética , Streptomyces griseus/crescimento & desenvolvimento
20.
Acad Radiol ; 23(1): 90-100, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26521686

RESUMO

RATIONALE AND OBJECTIVES: The current paradigm of cancer diagnosis involves uncoordinated communication of findings from radiology and pathology to downstream physicians. Discordance between these findings can require additional time from downstream users to resolve, or given incorrect resolution, may adversely impact treatment decisions. To mitigate this problem, we developed a web-based system, called RadPath, for correlating and integrating radiology and pathology reporting. MATERIALS AND METHODS: RadPath includes interfaces to our institution's clinical information systems, which are used to retrieve reports, images, and test results that are structured into an interactive compendium for a diagnostic patient case. The system includes an editing interface for physicians, allowing for the inclusion of additional clinical data, as well as the ability to retrospectively correlate and contextualize imaging findings following pathology diagnosis. RESULTS: During pilot deployment and testing over the course of 1 year, physicians at our institution have completed 60 RadPath cases, requiring an average of 128 seconds from a radiologist and an average of 93 seconds from a pathologist per case. Several technical and workflow challenges were encountered during development, including interfacing with diverse clinical information systems, automatically structuring report contents, and determining the appropriate physicians to create RadPath summaries. Reaction to RadPath has been positive, with users valuing the system's ability to consolidate diagnostic information. CONCLUSIONS: With the increasing complexity of medicine and the movement toward team-based disease management, there is a need for improved clinical communication and information exchange. RadPath provides a platform for generating coherent and correlated diagnostic summaries in cancer diagnosis with minimal additional effort from physicians.


Assuntos
Internet , Neoplasias/diagnóstico por imagem , Sistemas de Informação em Radiologia/organização & administração , Registros Eletrônicos de Saúde , Humanos , Armazenamento e Recuperação da Informação , Neoplasias/patologia , Radiologistas , Fluxo de Trabalho
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