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1.
Cell ; 173(2): 456-469.e16, 2018 04 05.
Artigo em Inglês | MEDLINE | ID: mdl-29576453

RESUMO

Following a previous microbial inoculation, plants can induce broad-spectrum immunity to pathogen infection, a phenomenon known as systemic acquired resistance (SAR). SAR establishment in Arabidopsis thaliana is regulated by the Lys catabolite pipecolic acid (Pip) and flavin-dependent-monooxygenase1 (FMO1). Here, we show that elevated Pip is sufficient to induce an FMO1-dependent transcriptional reprogramming of leaves that is reminiscent of SAR. In planta and in vitro analyses demonstrate that FMO1 functions as a pipecolate N-hydroxylase, catalyzing the biochemical conversion of Pip to N-hydroxypipecolic acid (NHP). NHP systemically accumulates in plants after microbial attack. When exogenously applied, it overrides the defect of NHP-deficient fmo1 in acquired resistance and acts as a potent inducer of plant immunity to bacterial and oomycete infection. Our work has identified a pathogen-inducible L-Lys catabolic pathway in plants that generates the N-hydroxylated amino acid NHP as a critical regulator of systemic acquired resistance to pathogen infection.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Oxigenases/metabolismo , Ácidos Pipecólicos/metabolismo , Imunidade Vegetal/efeitos dos fármacos , Arabidopsis/enzimologia , Arabidopsis/imunologia , Proteínas de Arabidopsis/genética , Cromatografia Gasosa-Espectrometria de Massas , Lisina/metabolismo , Oomicetos/patogenicidade , Oxigenases/genética , Ácidos Pipecólicos/análise , Ácidos Pipecólicos/farmacologia , Folhas de Planta/enzimologia , Folhas de Planta/imunologia , Folhas de Planta/metabolismo , Pseudomonas syringae/patogenicidade , Transaminases/genética , Transaminases/metabolismo
2.
Nature ; 574(7779): 505-510, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31645734

RESUMO

The promise of quantum computers is that certain computational tasks might be executed exponentially faster on a quantum processor than on a classical processor1. A fundamental challenge is to build a high-fidelity processor capable of running quantum algorithms in an exponentially large computational space. Here we report the use of a processor with programmable superconducting qubits2-7 to create quantum states on 53 qubits, corresponding to a computational state-space of dimension 253 (about 1016). Measurements from repeated experiments sample the resulting probability distribution, which we verify using classical simulations. Our Sycamore processor takes about 200 seconds to sample one instance of a quantum circuit a million times-our benchmarks currently indicate that the equivalent task for a state-of-the-art classical supercomputer would take approximately 10,000 years. This dramatic increase in speed compared to all known classical algorithms is an experimental realization of quantum supremacy8-14 for this specific computational task, heralding a much-anticipated computing paradigm.

3.
Plant Cell ; 33(3): 714-734, 2021 05 05.
Artigo em Inglês | MEDLINE | ID: mdl-33955482

RESUMO

Glucosylation modulates the biological activity of small molecules and frequently leads to their inactivation. The Arabidopsis thaliana glucosyltransferase UGT76B1 is involved in conjugating the stress hormone salicylic acid (SA) as well as isoleucic acid (ILA). Here, we show that UGT76B1 also glucosylates N-hydroxypipecolic acid (NHP), which is synthesized by FLAVIN-DEPENDENT MONOOXYGENASE 1 (FMO1) and activates systemic acquired resistance (SAR). Upon pathogen attack, Arabidopsis leaves generate two distinct NHP hexose conjugates, NHP-O-ß-glucoside and NHP glucose ester, whereupon only NHP-O-ß-glucoside formation requires a functional SA pathway. The ugt76b1 mutants specifically fail to generate the NHP-O-ß-glucoside, and recombinant UGT76B1 synthesizes NHP-O-ß-glucoside in vitro in competition with SA and ILA. The loss of UGT76B1 elevates the endogenous levels of NHP, SA, and ILA and establishes a constitutive SAR-like immune status. Introgression of the fmo1 mutant lacking NHP biosynthesis into the ugt76b1 background abolishes this SAR-like resistance. Moreover, overexpression of UGT76B1 in Arabidopsis shifts the NHP and SA pools toward O-ß-glucoside formation and abrogates pathogen-induced SAR. Our results further indicate that NHP-triggered immunity is SA-dependent and relies on UGT76B1 as a common metabolic hub. Thereby, UGT76B1-mediated glucosylation controls the levels of active NHP, SA, and ILA in concert to balance the plant immune status.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Glicosiltransferases/metabolismo , Ácidos Pipecólicos/metabolismo , Imunidade Vegetal/fisiologia , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Glicosiltransferases/genética , Imunidade Vegetal/genética
4.
Biotechnol Bioeng ; 2024 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-38837221

RESUMO

Advances in upstream production of biologics-particularly intensified fed-batch processes beyond 10% cell solids-have severely strained harvest operations, especially depth filtration. Bioreactors containing high amounts of cell debris (more than 40% particles <10 µm in diameter) are increasingly common and drive the need for more robust depth filtration processes, while accelerated timelines emphasize the need for predictive tools to accelerate development. Both needs are constrained by the current limited mechanistic understanding of the harvest filter-feedstream system. Historically, process development relied on screening scale-down depth filter devices and conditions to define throughput before fouling, indicated by increasing differential pressure and/or particle breakthrough (measured via turbidity). This approach is straightforward, but resource-intensive, and its results are inherently limited by the variability of the feedstream. Semi-empirical models have been developed from first principles to describe various mechanisms of filter fouling, that is, pore constriction, pore blocking, and/or surface deposit. Fitting these models to experimental data can assist in identifying the dominant fouling mechanism. Still, this approach sees limited application to guide process development, as it is descriptive, not predictive. To address this gap, we developed a hybrid modeling approach. Leveraging historical bench scale filtration process data, we built a partial least squares regression model to predict particle breakthrough from filter and feedstream attributes, and leveraged the model to demonstrate prediction of filter performance a priori. The fouling models are used to interpret and provide physical meaning to these computational models. This hybrid approach-combining the mechanistic insights of fouling models and the predictive capability of computational models-was used to establish a robust platform strategy for depth filtration of Chinese hamster ovary cell cultures. As new data continues to teach the computational models, in silico tools will become an essential part of harvest process development by enabling prospective experimental design, reducing total experimental load, and accelerating development under strict timelines.

5.
Environ Res ; 247: 118244, 2024 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-38266901

RESUMO

The usage and disposal of highly abundant single-use and multilayered plastics contribute to significant ecological problems. The thermochemical recovery of these plastics to useful products and chemicals provides opportunity for positive economic and environmental impacts. Most previous research use idealised and unrepresentative feedstocks. To address this, various mixed waste plastics collected from the rejected fraction of a municipal waste recovery facility in Ghana were pyrolyzed at varying temperatures of 450, 500 and 550 °C and their yields compared. The obtained chemical products were analysed using several different techniques. Energy and carbon balances of the processes were produced using the CHNS and energy content of the oil fraction and the compositional results of the pyrolysis gas fraction, the latter of which was measured by Gas Chromatography Thermal Conductivity Detection (GC-TCD). The oils were further assessed via Gas Chromatography Mass Spectrometry (GC-MS) to identify the available valuable compounds. The formed oil contained approximately 40% light hydrocarbons (C6 - C11), 18% middle hydrocarbons (C11 - C16) and 42% heavy hydrocarbon compounds (C16+). The optimal oil yield of 65.9 ± 0.5% and low heating value of 44.7 ± 0.1 MJ/kg for single-use plastics were recorded at highest heating temperatures of 550 and 500 °C, respectively. The findings provide indication that pyrolysis is a fitting solution for energy recovery from waste plastics.


Assuntos
Hidrocarbonetos , Plásticos , Óleos , Temperatura Alta , Temperatura
6.
New Phytol ; 237(4): 1285-1301, 2023 02.
Artigo em Inglês | MEDLINE | ID: mdl-36319610

RESUMO

Expression of OXIDATIVE SIGNAL-INDUCIBLE1 (OXI1) is induced by a number of stress conditions and regulates the interaction of plants with pathogenic and beneficial microbes. In this work, we generated Arabidopsis OXI1 knockout and genomic OXI1 overexpression lines and show by transcriptome, proteome, and metabolome analysis that OXI1 triggers ALD1, SARD4, and FMO1 expressions to promote the biosynthesis of pipecolic acid (Pip) and N-hydroxypipecolic acid (NHP). OXI1 contributes to enhanced immunity by induced SA biosynthesis via CBP60g-induced expression of SID2 and camalexin accumulation via WRKY33-targeted transcription of PAD3. OXI1 regulates genes involved in reactive oxygen species (ROS) generation such as RbohD and RbohF. OXI1 knock out plants show enhanced expression of nuclear and chloroplast genes of photosynthesis and enhanced growth under ambient conditions, while OXI1 overexpressing plants accumulate NHP, SA, camalexin, and ROS and show a gain-of-function (GOF) cell death phenotype and enhanced pathogen resistance. The OXI1 GOF phenotypes are completely suppressed when compromising N-hydroxypipecolic acid (NHP) synthesis in the fmo1 or ald1 background, showing that OXI1 regulation of immunity is mediated via the NHP pathway. Overall, these results show that OXI1 plays a key role in basal and effector-triggered plant immunity by regulating defense and programmed cell death via biosynthesis of salicylic acid, N-hydroxypipecolic acid, and camalexin.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Regulação da Expressão Gênica de Plantas , Estresse Oxidativo , Doenças das Plantas , Imunidade Vegetal , Espécies Reativas de Oxigênio/metabolismo , Ácido Salicílico/metabolismo
7.
Br J Clin Pharmacol ; 89(8): 2552-2560, 2023 08.
Artigo em Inglês | MEDLINE | ID: mdl-37002812

RESUMO

AIMS: Prescribing information should follow a defined structure to help prescribers easily find required information. Often information appears in different sections of Summaries of Product Characteristics (SmPCs) in an inconsistent way. Still unknown is how this inconsistency affects absolute contraindications and how it can be improved. Thisstudy aimed to evaluate the structure of absolute contraindications in SmPCs based on absolute drug-drug contraindications (DDCI) in the section 'contraindications' and references to sections 'special warnings and precautions for use' (here as 'warnings') and 'interaction with other medicinal products and other forms of interaction' (here as 'interactions'). METHODS: SmPCs of 693 commonly prescribed drugs were analysed regarding absolute DDCI in 'contraindications' sections. References to sections on 'warnings' and 'interactions' were evaluated to characterize information provided about DDCI. RESULTS: Of 693 analysed SmPCs, 138 (19.9%) contained ≥1 absolute DDCI. Of 178 SmPCs that referred to sections on 'warnings' or 'interactions', 131 (73.6%) did not contain further information on absolute DDCI, whereas 47 (26.4%) did. Such additional information was found in sections on 'interactions' and 'warnings' in 41 (87.2%) and 9 (19.1%) SmPCs, respectively. CONCLUSIONS: Information regarding absolute DDCI was found not only in sections on 'contraindications' but also in sections on 'warnings' and 'interactions'. Information was not given with consistently straightforward phrasing and structure and so can leave uncertainty for prescribers. To improve drug safety, clear definitions and wording for absolute and relative contraindications should be provided, ideally in tables.


Assuntos
Contraindicações de Medicamentos , Rotulagem de Medicamentos , Humanos , Rotulagem de Medicamentos/normas
8.
Plant Physiol ; 186(3): 1679-1705, 2021 07 06.
Artigo em Inglês | MEDLINE | ID: mdl-33871649

RESUMO

N-hydroxypipecolic acid (NHP) accumulates in the plant foliage in response to a localized microbial attack and induces systemic acquired resistance (SAR) in distant leaf tissue. Previous studies indicated that pathogen inoculation of Arabidopsis (Arabidopsis thaliana) systemically activates SAR-related transcriptional reprogramming and a primed immune status in strict dependence of FLAVIN-DEPENDENT MONOOXYGENASE 1 (FMO1), which mediates the endogenous biosynthesis of NHP. Here, we show that elevations of NHP by exogenous treatment are sufficient to induce a SAR-reminiscent transcriptional response that mobilizes key components of immune surveillance and signal transduction. Exogenous NHP primes Arabidopsis wild-type and NHP-deficient fmo1 plants for a boosted induction of pathogen-triggered defenses, such as the biosynthesis of the stress hormone salicylic acid (SA), accumulation of the phytoalexin camalexin and branched-chain amino acids, as well as expression of defense-related genes. NHP also sensitizes the foliage systemically for enhanced SA-inducible gene expression. NHP-triggered SAR, transcriptional reprogramming, and defense priming are fortified by SA accumulation, and require the function of the transcriptional coregulator NON-EXPRESSOR OF PR GENES1 (NPR1). Our results suggest that NPR1 transduces NHP-activated immune signaling modes with predominantly SA-dependent and minor SA-independent features. They further support the notion that NHP functions as a mobile immune regulator capable of moving independently of active SA signaling between leaves to systemically activate immune responses.


Assuntos
Arabidopsis/genética , Arabidopsis/metabolismo , Ácidos Pipecólicos/metabolismo , Doenças das Plantas/genética , Doenças das Plantas/imunologia , Imunidade Vegetal/genética , Transdução de Sinais/genética , Arabidopsis/imunologia , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Variação Genética , Genótipo , Ácidos Pipecólicos/imunologia , Imunidade Vegetal/fisiologia , Folhas de Planta/metabolismo , Pseudomonas syringae/patogenicidade , Fatores de Transcrição
9.
J Cancer Educ ; 37(4): 983-993, 2022 08.
Artigo em Inglês | MEDLINE | ID: mdl-33128211

RESUMO

Cancer patients need access to high-quality information, when making decisions about oral cancer drugs. The internet is often used as a source of information published by highly heterogeneous providers. The objective was to evaluate the quality of website providers supplying online information about oral cancer drugs. One hundred websites were analyzed using content-related and formal criteria, selected from three existing evaluation methods used for cancer websites, for medical information (defined by the German Agency for Quality in Medicine), and for the "fact box" tool. A web search by a patient was simulated to identify websites to evaluate. ANOVA was used to assess information provided by non-profit organizations (governmental and non-governmental), online newspapers, for-profit organizations, and private/unknown providers. Content-related quality differences were found between online newspapers and all other categories, with online newspapers ranking significantly lower than for-profit and non-profit websites. As for formal criteria, for-profit providers scored significantly lower than non-profit providers and online newspapers for the aspect of transparency. Internet information on oral cancer drugs published by non-profit organizations constitutes the best available web-based source of information for cancer patients. Health literacy and e-health literacy should be promoted in the public domain to allow patients to reliably apply web-based information. Certification should be required by law to ensure fulfillment of requirements for data reliability and transparency (authorship and funding) before health professionals recommend websites to cancer patients.


Assuntos
Antineoplásicos , Letramento em Saúde , Neoplasias Bucais , Humanos , Internet , Neoplasias Bucais/tratamento farmacológico , Reprodutibilidade dos Testes
10.
J Gynecol Surg ; 38(3): 207-213, 2022 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-35785107

RESUMO

Objective: To describe pregnancy outcomes in women who conceived after undergoing transcervical fibroid ablation (TFA) as treatment for symptomatic uterine fibroids. Materials and Methods: TFA was used to treat symptomatic uterine fibroids with radiofrequency energy, both under clinical trial protocol and commercial usage in hospitals in Europe, the United Kingdom, Mexico, and the United States. All women who reported pregnancies to their physicians after undergoing TFA with the Sonata® System and provided consent for use of their data were included. Results: There have been 36 pregnancies representing 20 deliveries among 28 women who were treated with TFA. Five women conceived more than once postablation, and four conceived as a result of assisted reproductive technology (ART). Outcomes include 8 vaginal deliveries, 12 Cesarean sections, 3 therapeutic abortions, and 8 first trimester spontaneous abortions (four occurring in a patient with a history of recurrent pregnancy loss and an immunologic disorder). Five women are currently pregnant, two of whom previously delivered after TFA. There were no 5-minute Apgar scores <7, and all neonates weighed >2500 g. All deliveries occurred at ≥37 weeks except for one delivery at 35 6/7 weeks. There were no uterine ruptures or abnormal placentation and no reports of postpartum hemorrhage or stillbirths. Ablated fibroids included transmural, submucous, and intramural myomata up to 7 cm in diameter. Conclusions: Normal pregnancy outcomes at term have occurred after TFA with the Sonata System, including in women with recurrent abortion and in those undergoing ART. There were no instances of low Apgar scores, low birthweight, stillbirth, postpartum hemorrhage, or uterine rupture (FAST-EU, NCT01226290; SONATA, NCT02228174; SAGE, NCT03 118037). (J GYNECOL SURG 38:207).

11.
J Biol Chem ; 295(15): 4963-4973, 2020 04 10.
Artigo em Inglês | MEDLINE | ID: mdl-32086380

RESUMO

Taxol (paclitaxel) is a very widely used anticancer drug, but its commercial sources mainly consist of stripped bark or suspension cultures of members of the plant genus Taxus. Taxol accumulates as part of a complex mixture of chemical analogs, termed taxoids, which complicates its production in pure form, highlighting the need for metabolic engineering approaches for high-level Taxol production in cell cultures or microbial hosts. Here, we report on the characterization of acyl-activating enzymes (AAEs) that catalyze the formation of CoA esters of different organic acids relevant for the N-substitution of the 3-phenylisoserine side chain of taxoids. On the basis of similarities to AAE genes of known function from other organisms, we identified candidate genes in publicly available transcriptome data sets obtained with Taxus × media. We cloned 17 AAE genes, expressed them heterologously in Escherichia coli, purified the corresponding recombinant enzymes, and performed in vitro assays with 27 organic acids as potential substrates. We identified TmAAE1 and TmAAE5 as the most efficient enzymes for the activation of butyric acid (Taxol D side chain), TmAAE13 as the best candidate for generating a CoA ester of tiglic acid (Taxol B side chain), TmAAE3 and TmAAE13 as suitable for the activation of 4-methylbutyric acid (N-debenzoyl-N-(2-methylbutyryl)taxol side chain), TmAAE15 as a highly efficient candidate for hexanoic acid activation (Taxol C side chain), and TmAAE4 as suitable candidate for esterification of benzoic acid with CoA (Taxol side chain). This study lays important groundwork for metabolic engineering efforts aimed at improving Taxol production in cell cultures.


Assuntos
Acil Coenzima A/metabolismo , Coenzima A Ligases/metabolismo , Ésteres/metabolismo , Paclitaxel/química , Paclitaxel/metabolismo , Proteínas Recombinantes/metabolismo , Taxus/enzimologia , Sequência de Aminoácidos , Clonagem Molecular , Coenzima A Ligases/química , Coenzima A Ligases/genética , Escherichia coli/genética , Escherichia coli/crescimento & desenvolvimento , Escherichia coli/metabolismo , Proteínas Recombinantes/genética , Homologia de Sequência
12.
Medicina (Kaunas) ; 57(9)2021 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-34577916

RESUMO

Background and objectives: Despite a generally good prognosis, testicular cancer can be a life-altering event. We explored perceived positive and negative life changes after testicular cancer in terms of frequency, demographic and disease-related predictors, and associations with depression and anxiety. Materials and methods: All testicular cancer survivors receiving follow-up care at two specialized outpatient treatment facilities were approached at follow-up visits or via mail. We assessed a total of N = 164 patients (66% participation rate, mean time since diagnosis: 11.6 years, SD = 7.4) by the Posttraumatic Growth Inventory (PTGI, modified version assessing positive and negative changes for each of 21 items), Patient-Health-Questionnaire-9 (PHQ-9), and Generalized-Anxiety-Disorder-Scale-7 (GAD-7). We conducted controlled multivariate regression analyses. Results: Most survivors (87%) reported at least one positive change (mean number: 7.2, SD = 5.0, possible range: 0-21). The most frequent perceived positive changes were greater appreciation of life (62%), changed priorities in life (62%), and ability rely on others (51%). At least one negative change was perceived by 33% (mean number of changes: 1.1, SD = 2.5). Negative changes were most frequent for decreases in self-reliance (14%), personal strength (11%), and ability to express emotions (9%). A higher socioeconomic status was associated with more positive changes (ß = 0.25, 95% CI 0.08 to 0.42); no other association with demographic and disease-related predictors emerged. While positive life changes were not associated with depression (ß = -0.05, 95% CI -0.17 to 0.07) and anxiety (ß = 0.00, 95% CI -0.13 to 0.13), more negative life changes were significantly associated with higher depression (ß = 0.15, 95% CI -0.03 to 0.27) and anxiety (ß = 0.23, 95% CI 0.11 to 0.36). There was no significant interaction of positive and negative changes on depression or anxiety. Conclusions: Although positive life changes after testicular cancer are common, a significant number of survivors perceive negative changes in life domains that have been primarily investigated in terms of personal growth. Early identification of and psychosocial support for patients who perceive predominantly negative changes may contribute to prevention of prolonged symptoms of anxiety and depression.


Assuntos
Sobreviventes de Câncer , Neoplasias Embrionárias de Células Germinativas , Neoplasias Testiculares , Ansiedade/epidemiologia , Depressão/epidemiologia , Humanos , Masculino , Qualidade de Vida , Sobreviventes , Neoplasias Testiculares/epidemiologia
13.
Plant Physiol ; 181(3): 1008-1028, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31515446

RESUMO

Tocopherols are lipid-soluble antioxidants synthesized in plastids of plants and other photosynthetic organisms. The four known tocopherols, α-, ß-, γ-, and δ-tocopherol, differ in number and position of methyl groups on their chromanol head group. In unstressed Arabidopsis (Arabidopsis thaliana) leaves, α-tocopherol constitutes the main tocopherol form, whereas seeds predominantly contain γ-tocopherol. Here, we show that inoculation of Arabidopsis leaves with the bacterial pathogen Pseudomonas syringae induces the expression of genes involved in early steps of tocopherol biosynthesis and triggers strong accumulation of γ-tocopherol, moderate production of δ-tocopherol, and generation of the benzoquinol precursors of tocopherols. The pathogen-inducible biosynthesis of tocopherols is promoted by the immune regulators ENHANCED DISEASE SUSCEPTIBILITY1 and PHYTOALEXIN-DEFICIENT4. In addition, tocopherols accumulate in response to bacterial flagellin and reactive oxygen species. By quantifying tocopherol forms in inoculated wild-type plants and biosynthetic pathway mutants, we provide biochemical insights into the pathogen-inducible tocopherol pathway. Notably, vitamin E deficient2 (vte2) mutant plants, which are compromised in both tocopherol and benzoquinol precursor accumulation, exhibit increased susceptibility toward compatible P. syringae and possess heightened levels of markers of lipid peroxidation after bacterial infection. The deficiency of triunsaturated fatty acids in vte2-1 fatty acid desaturase3-2 (fad3-2) fad7-2 fad8 quadruple mutants prevents increased lipid peroxidation in the vte2 background and restores pathogen resistance to wild-type levels. Therefore, the tocopherol biosynthetic pathway positively influences salicylic acid accumulation and guarantees effective basal resistance of Arabidopsis against compatible P. syringae, possibly by protecting leaves from the pathogen-induced oxidation of trienoic fatty acid-containing lipids.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Tocoferóis/metabolismo , Arabidopsis/microbiologia , Proteínas de Arabidopsis/genética , Hidrolases de Éster Carboxílico/genética , Hidrolases de Éster Carboxílico/metabolismo , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Regulação da Expressão Gênica de Plantas/genética , Regulação da Expressão Gênica de Plantas/fisiologia , Imunidade Vegetal/genética , Imunidade Vegetal/fisiologia , Folhas de Planta/genética , Folhas de Planta/metabolismo , Pseudomonas syringae/patogenicidade
14.
Acc Chem Res ; 52(3): 695-703, 2019 Mar 19.
Artigo em Inglês | MEDLINE | ID: mdl-30742413

RESUMO

From size-dependent luminescence to localized surface plasmon resonances, the optical properties that emerge from common materials with nanoscale dimensions have been revolutionary. As nanomaterials get smaller, they approach molecular electronic structures, and this transition from bulk to molecular electronic properties is a subject of far-reaching impact. One class of nanomaterials that exhibit particularly interesting optoelectronic features at this size transition are coinage metal (i.e., group 11 elements copper, silver, and gold) nanoparticles with core diameters between approximately 1 to 3 nm (∼25-200 atoms). Coinage metal nanoparticles can exhibit red or near-infrared photoluminescence features that are not seen in either their molecular or larger nanoscale counterparts. This emission has been exploited both as a probe of electronic behavior at the nanoscale as well as in critical applications such as biological imaging and chemical sensing. Interestingly, it has been demonstrated that their photoluminescence figures of merit such as emission quantum yield, energy, and lifetime are largely independent of particle diameter. Instead, emission from particles at this size range depends heavily on the particle surface chemistry, which includes both its metallic composition and the capping ligand architecture. The strong influence of surface chemistry on these emergent optoelectronic phenomena has powerful implications for both the study and use of these particles, primarily due to the theoretically limitless possible surface ligand architectures and metallic compositions. In this Account, we highlight recent work that studies and uses surface chemistry-mediated photoluminescence from coinage metal nanoparticles. Specifically, we emphasize the distinct, as well as synergistic, roles of the nanoparticle capping ligand and the nanoparticle core for controlling and/or enhancing their near-infrared photoluminescence. We then discuss the implications of surface chemistry-mediated photoluminescence as it relates to downstream applications such as energy transfer, sensing, and biological imaging. We conclude by discussing current challenges that remain in the field, including opportunities to develop new particle synthetic routes, analytical tools, and physical frameworks with which to understand small nanoparticle emission. Taken together, we anticipate that these materials will be foundational both in understanding the unique transition from molecular to bulk electronic structures and in the development of nanomaterials that leverage this transition.

15.
J Exp Bot ; 71(20): 6444-6459, 2020 10 22.
Artigo em Inglês | MEDLINE | ID: mdl-32725118

RESUMO

Recent work has provided evidence for the occurrence of N-hydroxypipecolic acid (NHP) in Arabidopsis thaliana, characterized its pathogen-inducible biosynthesis by a three-step metabolic sequence from l-lysine, and established a central role for NHP in the regulation of systemic acquired resistance. Here, we show that NHP is biosynthesized in several other plant species in response to microbial attack, generally together with its direct metabolic precursor pipecolic acid and the phenolic immune signal salicylic acid. For example, NHP accumulates locally in inoculated leaves and systemically in distant leaves of cucumber in response to Pseudomonas syringae attack, in Pseudomonas-challenged tobacco and soybean leaves, in tomato inoculated with the oomycete Phytophthora infestans, in leaves of the monocot Brachypodium distachyon infected with bacterial (Xanthomonas translucens) and fungal (Magnaporthe oryzae) pathogens, and in M. oryzae-inoculated barley. Notably, resistance assays indicate that NHP acts as a potent inducer of acquired resistance to bacterial and fungal infection in distinct monocotyledonous and dicotyledonous species. Pronounced systemic accumulation of NHP in leaf phloem sap of locally inoculated cucumber supports a function for NHP as a phloem-mobile immune signal. Our study thus generalizes the existence and function of an NHP resistance pathway in plant systemic acquired resistance.


Assuntos
Arabidopsis , Xanthomonas , Ascomicetos , Ácidos Pipecólicos , Doenças das Plantas , Folhas de Planta , Pseudomonas syringae , Ácido Salicílico
16.
BMC Gastroenterol ; 20(1): 120, 2020 Apr 21.
Artigo em Inglês | MEDLINE | ID: mdl-32316925

RESUMO

BACKGROUND: Cabozantinib was approved by the European Medicines Agency and the Federal Drug Administration as an option for sorafenib-resistant advanced hepatocellular carcinoma, increasing overall survival and progression-free survival compared with placebo. We evaluated the cost-effectiveness of cabozantinib in the second-line setting for patients with an advanced hepatocellular carcinoma from the German statutory health insurance perspective compared with an US scenario using US prices. METHODS: A Markov model was developed to compare the costs and effectiveness of cabozantinib with best supportive care in the second-line treatment of advanced hepatocellular carcinoma over a lifetime horizon. Health outcomes were measured in discounted life years and discounted quality-adjusted life years. Survival probabilities were estimated using parametric survival distributions based on CELESTIAL trial data. Utilities were derived from the literature. Costs contained drugs, monitoring and adverse events measured in US Dollars. Model robustness was addressed in univariable, scenario and probabilistic sensitivity analyses. RESULTS: Cabozantinib generated a gain of 0.18 life years (0.15 quality-adjusted life years) compared with best supportive care. The total mean cost per patient was $56,621 for cabozantinib and $2064 for best supportive care in the German model resulting in incremental cost-effectiveness ratios for cabozantinib of $306,778/life year and $375,470/quality-adjusted life year. Using US prices generated costs of $177,496 for cabozantinib and $4630 for best supportive care and incremental cost-effectiveness ratios of $972,049/life year and $1,189,706/quality-adjusted life year. CONCLUSIONS: Our analysis established that assuming a willingness-to-pay threshold of $163,371/life year (quality-adjusted life year) for the German model and $188,559/life year (quality-adjusted life year) for the US model, cabozantinib is not cost-effective compared with best supportive care. Sensitivity analyses showed that cabozantinib was not cost-effective in almost all our scenarios.


Assuntos
Anilidas/uso terapêutico , Antineoplásicos/uso terapêutico , Carcinoma Hepatocelular/tratamento farmacológico , Neoplasias Hepáticas/tratamento farmacológico , Piridinas/uso terapêutico , Anilidas/economia , Antineoplásicos/economia , Carcinoma Hepatocelular/economia , Carcinoma Hepatocelular/mortalidade , Análise Custo-Benefício , Resistencia a Medicamentos Antineoplásicos , Alemanha , Humanos , Neoplasias Hepáticas/economia , Neoplasias Hepáticas/mortalidade , Cadeias de Markov , Piridinas/economia , Anos de Vida Ajustados por Qualidade de Vida , Sorafenibe/uso terapêutico , Análise de Sobrevida , Estados Unidos
17.
J Chem Phys ; 152(24): 244120, 2020 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-32610977

RESUMO

Many proteins in cells are capable of sensing and responding to piconewton-scale forces, a regime in which conformational changes are small but significant for biological processes. In order to efficiently and effectively sample the response of these proteins to small forces, enhanced sampling techniques will be required. In this work, we derive, implement, and evaluate an efficient method to simultaneously sample the result of applying any constant pulling force within a specified range to a molecular system of interest. We start from simulated tempering in force, whereby force is added as a linear bias on a collective variable to the system's Hamiltonian, and the coefficient is taken as a continuous auxiliary degree of freedom. We derive a formula for an average collective-variable-dependent force, which depends on a set of weights learned on-the-fly throughout a simulation, that reflect the limit where force varies infinitely quickly. Simulation data can then be used to retroactively compute averages of any observable at any force within the specified range. This technique is based on recent work deriving similar equations for infinite switch simulated tempering in temperature, which showed that the infinite switch limit is the most efficient for sampling. Here, we demonstrate that our method accurately samples molecular systems at all forces within a user defined force range simultaneously and show how it can serve as an enhanced sampling tool for cases where the pulling direction destabilizes states that have low free-energy at zero-force. This method is implemented in and freely distributed with the PLUMED open-source sampling library, and hence can be readily applied to problems using a wide range of molecular dynamics software packages.


Assuntos
Peptídeos/química , Algoritmos , Fenômenos Mecânicos , Simulação de Dinâmica Molecular , Estudo de Prova de Conceito
18.
Plant J ; 96(1): 5-21, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-30035374

RESUMO

l-lysine catabolic routes in plants include the saccharopine pathway to α-aminoadipate and decarboxylation of lysine to cadaverine. The current review will cover a third l-lysine metabolic pathway having a major role in plant systemic acquired resistance (SAR) to pathogen infection that was recently discovered in Arabidopsis thaliana. In this pathway, the aminotransferase AGD2-like defense response protein (ALD1) α-transaminates l-lysine and generates cyclic dehydropipecolic (DP) intermediates that are subsequently reduced to pipecolic acid (Pip) by the reductase SAR-deficient 4 (SARD4). l-pipecolic acid, which occurs ubiquitously in the plant kingdom, is further N-hydroxylated to the systemic acquired resistance (SAR)-activating metabolite N-hydroxypipecolic acid (NHP) by flavin-dependent monooxygenase1 (FMO1). N-hydroxypipecolic acid induces the expression of a set of major plant immune genes to enhance defense readiness, amplifies resistance responses, acts synergistically with the defense hormone salicylic acid, promotes the hypersensitive cell death response and primes plants for effective immune mobilization in cases of future pathogen challenge. This pathogen-inducible NHP biosynthetic pathway is activated at the transcriptional level and involves feedback amplification. Apart from FMO1, some cytochrome P450 monooxygenases involved in secondary metabolism catalyze N-hydroxylation reactions in plants. In specific taxa, pipecolic acid might also serve as a precursor in the biosynthesis of specialized natural products, leading to C-hydroxylated and otherwise modified piperidine derivatives, including indolizidine alkaloids. Finally, we show that NHP is glycosylated in Arabidopsis to form a hexose-conjugate, and then discuss open questions in Pip/NHP-related research.


Assuntos
Lisina/metabolismo , Ácidos Pipecólicos/metabolismo , Imunidade Vegetal , Arabidopsis/imunologia , Arabidopsis/metabolismo , Redes e Vias Metabólicas , Plantas/imunologia , Plantas/metabolismo
19.
Phys Rev Lett ; 122(25): 250502, 2019 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-31347862

RESUMO

In experimentally realistic situations, quantum systems are never perfectly isolated and the coupling to their environment needs to be taken into account. Often, the effect of the environment can be well approximated by a Markovian master equation. However, solving this master equation for quantum many-body systems becomes exceedingly hard due to the high dimension of the Hilbert space. Here we present an approach to the effective simulation of the dynamics of open quantum many-body systems based on machine-learning techniques. We represent the mixed many-body quantum states with neural networks in the form of restricted Boltzmann machines and derive a variational Monte Carlo algorithm for their time evolution and stationary states. We document the accuracy of the approach with numerical examples for a dissipative spin lattice system.

20.
Phys Rev Lett ; 122(18): 183601, 2019 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-31144878

RESUMO

Networks of nonlinear resonators offer intriguing perspectives as quantum simulators for nonequilibrium many-body phases of driven-dissipative systems. Here, we employ photon correlation measurements to study the radiation fields emitted from a system of two superconducting resonators in a driven-dissipative regime, coupled nonlinearly by a superconducting quantum interference device, with cross-Kerr interactions dominating over on-site Kerr interactions. We apply a parametrically modulated magnetic flux to control the linear photon hopping rate between the two resonators and its ratio with the cross-Kerr rate. When increasing the hopping rate, we observe a crossover from an ordered to a delocalized state of photons. The presented coupling scheme is intrinsically robust to frequency disorder and may therefore prove useful for realizing larger-scale resonator arrays.

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