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1.
Aesthetic Plast Surg ; 2024 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-38987313

RESUMO

PURPOSE: To analyze the upper eyelid contour after Müller's muscle conjunctiva resection (MMCR) performed by four different surgeons. METHODS: Comparative cross-sectional analysis of the pre- and postoperative contours of a control group and four groups of upper lids (n = 88) of 65 patients who underwent MMCR at four international centers. The procedure employed was essentially the same as described by Putterman but performed with different instruments to entrap the posterior lamella. Multiple medial and lateral margin lid distances were measured on Bézier lines expressing the pre- and postoperative lid contours. RESULTS: Preoperatively, two groups had significant lateral and medial ptosis. After MMCR, the lateral segment of the lid's contour was corrected in all groups. In the two groups with more pronounced ptosis, the nasal lid contour was undercorrected. CONCLUSIONS: In MMCR, regardless of the instrument used to entrap the posterior lamella, the amount of medial tissue resection is essential to avoid postoperative nasal undercorrection. LEVEL OF EVIDENCE III: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

2.
Molecules ; 28(3)2023 Jan 18.
Artigo em Inglês | MEDLINE | ID: mdl-36770658

RESUMO

The demand for bio-based and safer composite materials is increasing due to the growth of the industry, human population, and environmental concerns. In this framework, sustainable and safer cork-polymer composites (CPC), based on green low-density polyethylene (LDPE) were developed using melt-based technologies. Chitosan and polyethylene-graft-maleic anhydride (PE-g-MA) were employed to enhance the CPC's properties. The morphology, wettability, mechanical, thermal, and antibacterial properties of the CPC against Pseudomonas putida (P. putida) and Staphylococcus aureus (S. aureus) were examined. The CPC showed improved stiffness when compared with that of the LDPE matrix, preferably when combined with chitosan and PE-g-MA (5 wt. %), reinforcing the stiffness (58.8%) and the strength (66.7%). Chitosan also increased the composite stiffness and strength, as well as reduced the surface hydrophilicity. The CPCs' antibacterial activity revealed that cork significantly reduces the biofilm on the polymer matrix. The highest biofilm reduction was found with CPC containing cork and 5 wt. % chitosan for both P. putida (54% reduction) and S. aureus (36% reduction), confirming their potential to extend the lifespan of products for packaging and healthcare, among other applications. This work leads to the understanding of the factors that influence biofilm formation in cork composites and provides a strategy to reinforce their behavior using chitosan.


Assuntos
Incrustação Biológica , Quitosana , Humanos , Quitosana/farmacologia , Polietileno , Incrustação Biológica/prevenção & controle , Staphylococcus aureus , Antibacterianos/farmacologia , Polímeros
3.
New Phytol ; 234(5): 1598-1605, 2022 06.
Artigo em Inglês | MEDLINE | ID: mdl-35279849

RESUMO

Xylella fastidiosa is the causal agent of important crop diseases and is transmitted by xylem-sap-feeding insects. The bacterium colonizes xylem vessels and can persist with a commensal or pathogen lifestyle in more than 500 plant species. In the past decade, reports of X. fastidiosa across the globe have dramatically increased its known occurrence. This raises important questions: How does X. fastidiosa interact with the different host plants? How does the bacterium interact with the plant immune system? How does it influence the host's microbiome? We discuss recent strain genetic typing and plant transcriptome and microbiome analyses, which have advanced our understanding of factors that are important for X. fastidiosa plant infection.


Assuntos
Microbiota , Xylella , Doenças das Plantas/microbiologia , Plantas
4.
J Sports Sci ; 40(3): 364-369, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34706625

RESUMO

Phosphatidic acid (PA) is a lipid mediator proposed to increase muscle protein synthesis via direct stimulation of the mammalian target of rapamycin (mTOR) and may act as an anabolic supplemental aid. Evidence on the effectiveness of PA as an anabolic supplement is equivocal. We aimed to systematically assess the effect of PA on performance and body composition. Due to the small number of studies, this is a scoping review. A comprehensive search was performed in Pubmed, SPORTDiscus and Web of Science, from the 1 January 2010 to the 31 August 2020. Our search retrieved 2009 articles, which when filtered, resulted in six studies, published between 2012 and 2019, which were analysed further. Five studies were performed in adult male populations and one in an elderly male population. From these, three studies suggested no effect of PA on lean body mass , while the remaining showed a possible positive effect (body composition and performance improvements). In one of these, the supplement included other potentially anabolic substances, precluding an isolated effect of PA. After a thorough analysis of the studies included, the evidence does not support the supplementation with PA to increase performance or improve body composition in young or elderly men.


Assuntos
Composição Corporal , Ácidos Fosfatídicos , Adulto , Idoso , Suplementos Nutricionais , Humanos , Masculino , Proteínas Musculares/metabolismo , Ácidos Fosfatídicos/metabolismo , Ácidos Fosfatídicos/farmacologia
5.
Int J Mol Sci ; 23(23)2022 Nov 24.
Artigo em Inglês | MEDLINE | ID: mdl-36498973

RESUMO

Marine biofouling is a natural process often associated with biofilm formation on submerged surfaces, creating a massive economic and ecological burden. Although several antifouling paints have been used to prevent biofouling, growing ecological concerns emphasize the need to develop new and environmentally friendly antifouling approaches such as bio-based coatings. Chitosan (CS) is a natural polymer that has been widely used due to its outstanding biological properties, including non-toxicity and antimicrobial activity. This work aims to produce and characterize poly (lactic acid) (PLA)-CS surfaces with CS of different molecular weight (Mw) at different concentrations for application in marine paints. Loligo opalescens pens, a waste from the fishery industry, were used as a CS source. The antimicrobial activity of the CS and CS-functionalized surfaces was assessed against Cobetia marina, a model proteobacterium for marine biofouling. Results demonstrate that CS targets the bacterial cell membrane, and PLA-CS surfaces were able to reduce the number of culturable cells up to 68% compared to control, with this activity dependent on CS Mw. The antifouling performance was corroborated by Optical Coherence Tomography since PLA-CS surfaces reduced the biofilm thickness by up to 36%, as well as the percentage and size of biofilm empty spaces. Overall, CS coatings showed to be a promising approach to reducing biofouling in marine environments mimicked in this work, contributing to the valorization of fishing waste and encouraging further research on this topic.


Assuntos
Anti-Infecciosos , Incrustação Biológica , Quitosana , Quitosana/farmacologia , Incrustação Biológica/prevenção & controle , Biofilmes , Pintura
6.
Langmuir ; 37(27): 8177-8189, 2021 07 13.
Artigo em Inglês | MEDLINE | ID: mdl-34184901

RESUMO

It is well established that many leaf surfaces display self-cleaning properties. However, an understanding of how the surface properties interact is still not achieved. Consequently, 12 different leaf types were selected for analysis due to their water repellency and self-cleaning properties. The most hydrophobic surfaces demonstrated splitting of the νs CH2 and ν CH2 bands, ordered platelet-like structures, crystalline waxes, high-surface-roughness values, high-total-surface-free energy and apolar components of surface energy, and low polar and Lewis base components of surface energy. The surfaces that exhibited the least roughness and high polar and Lewis base components of surface energy had intracuticular waxes, yet they still demonstrated the self-cleaning action. Principal component analysis demonstrated that the most hydrophobic species shared common surface chemistry traits with low intra-class variability, while the less hydrophobic leaves had highly variable surface-chemistry characteristics. Despite this, we have shown through partial least squares regression that the leaf water contact angle (i.e., hydrophobicity) can be predicted using attenuated total reflectance Fourier transform infrared spectroscopy surface chemistry data with excellent ability. This is the first time that such a statistical analysis has been performed on a complex biological system. This model could be utilized to investigate and predict the water contact angles of a range of biological surfaces. An understanding of the interplay of properties is extremely important to produce optimized biomimetic surfaces.


Assuntos
Folhas de Planta , Ceras , Interações Hidrofóbicas e Hidrofílicas , Análise de Componente Principal , Propriedades de Superfície
7.
Environ Res ; 198: 111219, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33965385

RESUMO

The control of marine biofouling has raised serious environmental concerns, thus the continuous release of toxic and persistent biocidal agents applied as anti-biofouling coatings have triggered the search for non-toxic strategies. However, most of them still lack rigorous evaluation of their ecotoxicity and antifouling effects under real scenarios and their correlation with simulated assays. In this work, the biocide releasing risk and ecotoxicity of a biocidal and foul-release polydimethylsiloxane (PDMS)-based marine coating containing grafted Econea biocide (<0.6 wt.%) were evaluated under simulated real mechanical wear conditions at a pilot-scale system, and under extreme wear scenarios (washability settings). The coating system demonstrated low environmental impact against the model Vibrio fischeri bacterium and marine algae, associated with the effective biocide grafting in the coating matrix and subsequent biocide release minimization. This multifunctional coating system also showed auspicious antifouling (AF) effects, with an AF performance index significantly higher (API > 89) than a single foul-release system (AF < 40) after two and half years at a real immersion scenario in the Portuguese shore of the Atlantic Ocean. These field results corroborated the antibiofilm performance evaluated with Pseudoalteromonas tunicata at simulated dynamic marine conditions after seven-week assays. This eco-friendly multifunctional strategy, validated by both simulated testing conditions and real field tests, is believed to be a powerful tool for the development of AF technologies and a potential contribution to the quest for new environmentally friendly antifouling solutions.


Assuntos
Incrustação Biológica , Desinfetantes , Incrustação Biológica/prevenção & controle , Desinfetantes/toxicidade , Pseudoalteromonas
8.
Mar Drugs ; 19(7)2021 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-34356809

RESUMO

The growing requirement for sustainable processes has boosted the development of biodegradable plastic-based materials incorporating bioactive compounds obtained from waste, adding value to these products. Chitosan (Ch) is a biopolymer that can be obtained by deacetylation of chitin (found abundantly in waste from the fishery industry) and has valuable properties such as biocompatibility, biodegradability, antimicrobial activity, and easy film-forming ability. This study aimed to produce and characterize poly(lactic acid) (PLA) surfaces coated with ß-chitosan and ß-chitooligosaccharides from a Loligo opalescens pen with different molecular weights for application in the food industry. The PLA films with native and depolymerized Ch were functionalized through plasma oxygen treatment followed by dip-coating, and their physicochemical properties were assessed by Fourier-transform infrared spectroscopy, X-ray diffraction, water contact angle, and scanning electron microscopy. Their antimicrobial properties were assessed against Escherichia coli and Pseudomonas putida, where Ch-based surfaces reduced the number of biofilm viable, viable but nonculturable, and culturable cells by up to 73%, 74%, and 87%, respectively, compared to PLA. Biofilm growth inhibition was confirmed by confocal laser scanning microscopy. Results suggest that Ch films of higher molecular weight had higher antibiofilm activity under the food storage conditions mimicked in this work, contributing simultaneously to the reuse of marine waste.


Assuntos
Antibacterianos/farmacologia , Quitosana/química , Loligo , Animais , Organismos Aquáticos , Biofilmes/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Embalagem de Alimentos , Peso Molecular , Espectroscopia de Infravermelho com Transformada de Fourier
9.
Molecules ; 26(14)2021 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-34299652

RESUMO

Implantable medical devices (IMDs) are susceptible to microbial adhesion and biofilm formation, which lead to several clinical complications, including the occurrence of implant-associated infections. Polylactic acid (PLA) and its composites are currently used for the construction of IMDs. In addition, chitosan (CS) is a natural polymer that has been widely used in the medical field due to its antimicrobial and antibiofilm properties, which can be dependent on molecular weight (Mw). The present study aims to evaluate the performance of CS-based surfaces of different Mw to inhibit bacterial biofilm formation. For this purpose, CS-based surfaces were produced by dip-coating and the presence of CS and its derivatives onto PLA films, as well surface homogeneity were confirmed by contact angle measurements, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The antimicrobial activity of the functionalized surfaces was evaluated against single- and dual-species biofilms of Staphylococcus aureus and Pseudomonas aeruginosa. Chitosan-based surfaces were able to inhibit the development of single- and dual-species biofilms by reducing the number of total, viable, culturable, and viable but nonculturable cells up to 79%, 90%, 81%, and 96%, respectively, being their activity dependent on chitosan Mw. The effect of CS-based surfaces on the inhibition of biofilm formation was corroborated by biofilm structure analysis using confocal laser scanning microscopy (CLSM), which revealed a decrease in the biovolume and thickness of the biofilm formed on CS-based surfaces compared to PLA. Overall, these results support the potential of low Mw CS for coating polymeric devices such as IMDs where the two bacteria tested are common colonizers and reduce their biofilm formation.


Assuntos
Biofilmes/efeitos dos fármacos , Quitosana , Implantes Experimentais/microbiologia , Pseudomonas aeruginosa/fisiologia , Staphylococcus aureus/fisiologia , Biofilmes/crescimento & desenvolvimento , Quitosana/química , Quitosana/farmacologia , Propriedades de Superfície
10.
Aging Male ; 23(5): 669-678, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30767598

RESUMO

Hypogonadism affects an extensive part of the male population, especially among the elderly. The quest for treatment regarding low levels of serum testosterone and male infertility has, therefore, worldwide relevance. Zinc has important biological actions insofar as the male reproductive physiology and endocrine system. In general, a common and safe recommendation for zinc in the treatment of male hypogonadism is 220 mg of zinc sulfate (equivalent to 50 mg of elemental zinc) twice a day, over one to four months. Additionally, it may be further required to extend, both the treatment, dose and daily fractionation of this mineral. Albeit medicinal doses of zinc may increase total testosterone and improve sperm count, the current body of evidence does not suggest broad recommendations regarding the use of zinc for all types of hypogonadism. In many cases, the use of zinc supplements is insufficient, with the use of surgery and drugs being required for an effective treatment.


Assuntos
Hipogonadismo , Infertilidade Masculina , Preparações Farmacêuticas , Idoso , Humanos , Hipogonadismo/tratamento farmacológico , Infertilidade Masculina/tratamento farmacológico , Masculino , Testosterona , Zinco
11.
Biofouling ; 36(6): 631-645, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32715767

RESUMO

Cyanobacteria promote marine biofouling with significant impacts. A qualitative proteomic analysis, by LC-MS/MS, of planktonic and biofilm cells from two cyanobacteria was performed. Biofilms were formed on glass and perspex at two relevant hydrodynamic conditions for marine environments (average shear rates of 4 s-1 and 40 s-1). For both strains and surfaces, biofilm development was higher at 4 s-1. Biofilm development of Nodosilinea sp. LEGE 06145 was substantially higher than Nodosilinea sp. LEGE 06119, but no significant differences were found between surfaces. Overall, 377 and 301 different proteins were identified for Nodosilinea sp. LEGE 06145 and Nodosilinea sp. LEGE 06119. Differences in protein composition were more noticeable in biofilms formed under different hydrodynamic conditions than in those formed on different surfaces. Ribosomal and photosynthetic proteins were identified in most conditions. The characterization performed gives new insights into how shear rate and surface affect the planktonic to biofilm transition, from a structural and proteomics perspective.


Assuntos
Biofilmes , Cianobactérias , Plâncton , Proteômica , Cromatografia Líquida , Espectrometria de Massas em Tandem
12.
Environ Microbiol ; 21(11): 4411-4424, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31573125

RESUMO

Marine biofouling has severe economic impacts and cyanobacteria play a significant role as early surface colonizers. Despite this fact, cyanobacterial biofilm formation studies in controlled hydrodynamic conditions are scarce. In this work, computational fluid dynamics was used to determine the shear rate field on coupons that were placed inside the wells of agitated 12-well microtiter plates. Biofilm formation by three different cyanobacterial strains was assessed at two different shear rates (4 and 40 s-1 ) which can be found in natural ecosystems and using different surfaces (glass and perspex). Biofilm formation was higher under low shear conditions, and differences obtained between surfaces were not always statistically significant. The hydrodynamic effect was more noticeable during the biofilm maturation phase rather than during initial cell adhesion and optical coherence tomography showed that different shear rates can affect biofilm architecture. This study is particularly relevant given the cosmopolitan distribution of these cyanobacterial strains and the biofouling potential of these organisms.


Assuntos
Biofilmes , Cianobactérias/fisiologia , Hidrodinâmica
13.
Pharmacol Res ; 144: 245-256, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31005617

RESUMO

Cancer remains a public health challenge in the identification and development of ideal pharmacological therapies and dietary strategies. The use of whey protein as a dietary strategy is widespread in the field of oncology. The two types of whey protein, sweet or acid, result from several processing techniques and possess distinct protein subfraction compositions. Mechanistically, whey protein subfractions have specific anti-cancer effects. Alpha-lactalbumin, human α-lactalbumin made lethal to tumor cell, bovine α-lactalbumin made lethal to tumor cell, bovine serum albumin, and lactoferrin are whey protein subfractions with potential to hinder tumor pathways. Such effects, however, are principally supported by studies performed in vitro and/or in vivo. In clinical practice, whey protein intake-induced anti-cancer effects are indiscernible. However, whey protein supplementation represents a practical, feasible, and cost-effective approach to mitigate cancer cachexia syndrome. The usefulness of whey protein is evidenced by a greater leucine content and the potential to modulate IGF-1 concentrations, representing important factors towards musculoskeletal hypertrophy. Further clinical trials are warranted and needed to establish the effects of whey protein supplementation as an adjuvant to cancer therapy.


Assuntos
Neoplasias/terapia , Proteínas do Soro do Leite/uso terapêutico , Animais , Caquexia/etiologia , Caquexia/metabolismo , Caquexia/terapia , Suplementos Nutricionais , Humanos , Fator de Crescimento Insulin-Like I/metabolismo , Neoplasias/complicações , Neoplasias/metabolismo
14.
J Sports Sci ; 37(17): 2037-2044, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31079555

RESUMO

Leucine metabolites may reduce training-induced inflammation; however, there is scant evidence for this assertion. We conducted a double-blind randomized controlled pragmatic trial where 40 male participants were allocated into 4 groups: α-hydroxyisocaproic acid group ([α-HICA], n = 10, Fat-free mass [FFM] = 62.0 ± 7.1 kg), ß-hydroxy-ß-methylbutyrate free acid group ([HMB-FA], n = 11, FFM = 62.7 ± 10.5 kg), calcium ß-hydroxy-ß-methylbutyrate group ([HMB-Ca], n = 9, FFM = 65.6 ± 10.1 kg) or placebo group ([PLA]; n = 10, FFM = 64.2 ± 5.7 kg). An 8-week whole-body resistance training routine (3 training sessions per week) was employed to induce gains in skeletal-muscle thickness. Skeletal muscle thickness (MT), one repetition maximum (1RM), interleukin-6 (IL-6), high-sensitivity C-reactive protein (hsCRP) and tumour necrosis factor alpha (TNF-α) were assessed at baseline and at the end of weeks 4 and 8. Time-dependent increases were detected from baseline to week 8 for MT (vastus lateralis: p = 0.009; rectus femoris: p = 0.018), 1RM (back squat: α-HICA, 18.5% ± 18.9%; HMB-FA, 23.2% ± 16%; HMB-Ca, 10.5% ± 13.8%; PLA, 19.7% ± 9% and bench press: α-HICA, 13.8% ± 19.1%; HMB-FA, 15.5% ± 9.3%; HMB-Ca, 10% ± 10.4%; PLA, 14.4 ± 11.3%, both p < 0.001), IL-6, hsCRP (both p < 0.001) and TNF-α (p = 0.045). No differences were found between groups at any time point. No leucine metabolite attenuated inflammation during training. Additionally, backwards elimination regressions showed that no circulating inflammatory marker consistently shared variance with the change in any outcome. Using leucine metabolites to modulate inflammation cannot be recommended from the results obtained herein. Furthermore, increases in inflammatory markers, from training, do not correlate with any outcome variable and are likely the result of training adaptations.


Assuntos
Caproatos/administração & dosagem , Inflamação/sangue , Leucina/metabolismo , Treinamento Resistido , Fenômenos Fisiológicos da Nutrição Esportiva , Valeratos/administração & dosagem , Adulto , Biomarcadores/sangue , Composição Corporal , Proteína C-Reativa/análise , Cálcio , Suplementos Nutricionais , Método Duplo-Cego , Humanos , Interleucina-6/sangue , Masculino , Força Muscular , Músculo Esquelético/crescimento & desenvolvimento , Músculo Esquelético/fisiologia , Fator de Necrose Tumoral alfa/sangue , Adulto Jovem
15.
Ophthalmic Plast Reconstr Surg ; 35(6): 574-577, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30969191

RESUMO

PURPOSE: The evaluation of palpebral laxity can be performed by the distraction test (DT). Although widely used in ophthalmologic practice, there is no consensus about the results considered normal by the test. The objectives of this study are to obtain the value of DT in a group of individuals with healthy eyelids and to compare with the measurements in subjects with senile ectropion. METHODS: Lower eyelid DT was performed in 200 individuals without any eyelid pathology and in 30 individuals with lower lid ectropion. The results were analyzed by age and sex in the control group and compared with the results of the ectropion group. RESULTS: The mean value of DT in the control group was 6.96 mm, lower than in the ectropion group (9.48 mm) (p < 0.001). In the control group, the mean female DT was 6.70 mm, while the male was 7.22 mm. There were differences in the DT values in the subgroups of 20-39 and 40-59-year old according to gender, with men presenting higher measurements than women. In the other age subgroups, both genders presented similar DT values. Even when considering only individuals in the control group with the same range of age as in the ectropion group, the DT value was higher in individuals with ectropion (7.23 and 9.48 mm, respectively, p < 0.001). CONCLUSIONS: The mean DT value is 6.96 mm; however, the measurement varies according to age and sex in people without palpebral pathology. Individuals with senile eyelid ectropion present higher measurements than healthy ones.In this study, the authors performed the eyelid distraction test in 200 healthy individuals, bringing to the literature the new information that there is a variability of the normal test's value regarding age and gender.


Assuntos
Técnicas de Diagnóstico Oftalmológico , Ectrópio/patologia , Pálpebras/patologia , Adulto , Idoso , Estudos de Casos e Controles , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Valores de Referência
16.
Yale J Biol Med ; 91(2): 161-171, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29962922

RESUMO

Research involving dietary supplement interventions for sarcopenia and osteopenia in type 1 diabetes patients is scarce. Here we present a case study of a type 1 diabetic patient that was treated with supplemental alpha-hydroxy-isocaproic acid (α-HICA) for 120 days. Several measures of body composition by dual x-ray absorptiometry, blood markers, and maximum voluntary contraction parameters were assessed at baseline and after 120 days. The patient's baseline weight was 73.2 kg, which increased to 75.2 kg by the 120-day assessment. Salient mass distribution changes included increases of trunk fat mass (+0.4 kg), trunk fat free mass (+0.2 kg), total trunk mass (+0.2 kg), and a decrease of 8 percent in trunk fat mass contribution. Handgrip strength increased by 58.84 N, whereas isometric force in the leg press decreased by 347.15 N. Amelioration of BMD Z-scores from -0.7 to 0.5 and T-scores from -1.0 to -0.9 were noted. Importantly, full hematologic measures and weekly nutritional counselling assessments revealed no signs of adverse effects with α-HICA supplementation. Due to the imperative of maintaining FFM, strength and bone mass in these patients, additional research is necessary to confirm these promising results and to clarify whether leucine and/or one of its derivatives might be clinically useful.


Assuntos
Composição Corporal/efeitos dos fármacos , Caproatos/química , Caproatos/uso terapêutico , Diabetes Mellitus Tipo 1/tratamento farmacológico , Músculo Esquelético/efeitos dos fármacos , Músculo Esquelético/metabolismo , Atrofia Muscular/tratamento farmacológico , Diabetes Mellitus Tipo 1/metabolismo , Humanos , Masculino , Pessoa de Meia-Idade , Atrofia Muscular/metabolismo
17.
Org Biomol Chem ; 14(25): 5965-82, 2016 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-27223461

RESUMO

Cyclopropane rings are versatile building blocks in organic chemistry. Their synthesis, by the reaction of sulfur ylides with α,ß-unsaturated carbonyl compounds, has recently aroused renewed interest after the discovery of efficient catalysis by using (S)-indoline-2-carboxylic acid. In order to rationalize the behavior of this catalyst, MacMillan proposed a directed electrostatic activation (DEA) mechanism, in which the negative carboxylate group interacts with the positive thionium moiety, thus reducing the activation energy and increasing the reaction rate. More recently, Mayr refuted some of MacMillan conclusions, but accepted the DEA mechanism as a justification for the experimental high reaction rates. In contrast, our results indicate that the selectivity obtained in the process seems to result from several strong hydrogen bond interactions between the two reacting species, while no strong evidence for a DEA mechanism was found. We also concluded that the hydrogen bonds don't improve the reaction rate by lowering the activation energy of the rate-determining step, but can do it by promoting efficient reaction trajectories due to long-range complexation of the reagents. Finally, our results confirm that the cyclopropanation reaction occurs by a two-step mechanism, and that the overall enantioselectivity depends on the relative energies of the two steps, averaged by the relative populations of the iminium intermediates that are initially formed in the reaction.

18.
Anal Chem ; 87(13): 6487-92, 2015 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-26057348

RESUMO

The fabrication of an all-diamond microprobe is demonstrated for the first time. This ME (microelectrode) assembly consists of an inner boron doped diamond (BDD) layer and an outer undoped diamond layer. Both layers were grown on a sharp tungsten tip by chemical vapor deposition (CVD) in a stepwise manner within a single deposition run. BDD is a material with proven potential as an electrochemical sensor. Undoped CVD diamond is an insulating material with superior chemical stability in comparison to conventional insulators. Focused ion beam (FIB) cutting of the apex of the ME was used to expose an electroactive BDD disk. By cyclic voltammetry, the redox reaction of ferrocenemethanol was shown to take place at the BDD microdisk surface. In order to ensure that the outer layer was nonelectrically conductive, a diffusion barrier for boron atoms was established seeking the formation of boron-hydrogen complexes at the interface between the doped and the undoped diamond layers. The applicability of the microelectrodes in localized corrosion was demonstrated by scanning amperometric measurements of oxygen distribution above an Al-Cu-CFRP (Carbon Fiber Reinforced Polymer) galvanic corrosion cell.


Assuntos
Diamante , Técnicas Eletroquímicas/instrumentação , Microeletrodos , Sondas Moleculares
19.
Genome Res ; 22(11): 2270-7, 2012 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-22829535

RESUMO

Exceptionally accurate genome reference sequences have proven to be of great value to microbial researchers. Thus, to date, about 1800 bacterial genome assemblies have been "finished" at great expense with the aid of manual laboratory and computational processes that typically iterate over a period of months or even years. By applying a new laboratory design and new assembly algorithm to 16 samples, we demonstrate that assemblies exceeding finished quality can be obtained from whole-genome shotgun data and automated computation. Cost and time requirements are thus dramatically reduced.


Assuntos
Bactérias/genética , Genoma Bacteriano , Biblioteca Genômica , Análise de Sequência de DNA/métodos , Algoritmos
20.
Proc Natl Acad Sci U S A ; 108(4): 1513-8, 2011 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-21187386

RESUMO

Massively parallel DNA sequencing technologies are revolutionizing genomics by making it possible to generate billions of relatively short (~100-base) sequence reads at very low cost. Whereas such data can be readily used for a wide range of biomedical applications, it has proven difficult to use them to generate high-quality de novo genome assemblies of large, repeat-rich vertebrate genomes. To date, the genome assemblies generated from such data have fallen far short of those obtained with the older (but much more expensive) capillary-based sequencing approach. Here, we report the development of an algorithm for genome assembly, ALLPATHS-LG, and its application to massively parallel DNA sequence data from the human and mouse genomes, generated on the Illumina platform. The resulting draft genome assemblies have good accuracy, short-range contiguity, long-range connectivity, and coverage of the genome. In particular, the base accuracy is high (≥99.95%) and the scaffold sizes (N50 size = 11.5 Mb for human and 7.2 Mb for mouse) approach those obtained with capillary-based sequencing. The combination of improved sequencing technology and improved computational methods should now make it possible to increase dramatically the de novo sequencing of large genomes. The ALLPATHS-LG program is available at http://www.broadinstitute.org/science/programs/genome-biology/crd.


Assuntos
Algoritmos , Genômica/métodos , Análise de Sequência de DNA/métodos , Software , Animais , Genoma/genética , Humanos , Internet , Camundongos , Reprodutibilidade dos Testes
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