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1.
Nano Lett ; 23(15): 7166-7173, 2023 Aug 09.
Artigo em Inglês | MEDLINE | ID: mdl-37506183

RESUMO

A key aspect of how the brain learns and enables decision-making processes is through synaptic interactions. Electrical transmission and communication in a network of synapses are modulated by extracellular fields generated by ionic chemical gradients. Emulating such spatial interactions in synthetic networks can be of potential use for neuromorphic learning and the hardware implementation of artificial intelligence. Here, we demonstrate that in a network of hydrogen-doped perovskite nickelate devices, electric bias across a single junction can tune the coupling strength between the neighboring cells. Electrical transport measurements and spatially resolved diffraction and nanoprobe X-ray and scanning microwave impedance spectroscopic studies suggest that graded proton distribution in the inhomogeneous medium of hydrogen-doped nickelate film enables this behavior. We further demonstrate signal integration through the coupling of various junctions.

2.
Mucosal Immunol ; 15(3): 491-503, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-35177818

RESUMO

IL-36 cytokines are emerging as potent orchestrators of intestinal inflammation and are being implicated in the pathogenesis of inflammatory bowel diseases (IBD). However, the mechanisms through which these cytokines mediate these effects remain to be fully uncovered. Here, we report specifically elevated expression of IL-36α, and not IL-36ß or IL-36γ in the serum of newly diagnosed, treatment naïve, paediatric IBD patients and identify T cells as primary cellular mediators of IL-36 responses in the inflamed gut. IL-36R expression on CD4+ T cells was found to promote intestinal pathology in a murine model of colitis. Consistent with these effects, IL-36R can act as a potent instructor of CD4+ T cell differentiation in vivo, enhancing Th1 responses, while inhibiting the generation of Tregs. In addition, loss of IL-36 responsiveness significantly reduced the migration of pathogenic CD4+ T cells towards intestinal tissues and IL-36 was found to act, uniquely among IL-1 family members, to induce the expression of gut homing receptors in proinflammatory murine and human CD4+ T cells. These data reveal an important role for IL-36 cytokines in driving the colitogenic potential of CD4+ T cells and identify a new mechanism through which they may contribute to disease pathogenesis.


Assuntos
Colite , Doenças Inflamatórias Intestinais , Interleucinas/imunologia , Animais , Criança , Colite/metabolismo , Citocinas/metabolismo , Humanos , Doenças Inflamatórias Intestinais/metabolismo , Camundongos , Fenótipo , Linfócitos T Auxiliares-Indutores/metabolismo
3.
Accid Anal Prev ; 163: 106448, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34717203

RESUMO

This paper aims to assess the effects of snow and ice control operations by investigating the interdependency between weather variables, maintenance operations, pavement friction, and collisions. Using a disaggregated event-based and location-specific framework, and employing the statistical techniques of Structural Equation Modeling and Path Analysis, all the significant direct and indirect effects of weather variables and maintenance operations on pavement friction and collision occurrence during snowstorms have been identified. It was revealed that precipitation, extremely low temperatures, and the potential of black ice formation all had significant negative direct effects on pavement friction and significant indirect negative effects on traffic safety. Moreover, the application of anti-icing agents and plowing operations have been shown to significantly improve pavement friction and in return improve traffic safety indirectly. To illustrate how the maintenance operations improve traffic safety, a hypothetical snowstorm example was considered. According to the model, anti-icing application was associated with a 14% reduction in collisions, plowing operations resulted in a 33% reduction in collisions, and combining the two tools reduced collisions per snowstorm by 42%. The findings of this paper can help transportation agencies make more informed decisions to promote an efficient mobilization of the existing winter road maintenance services and resources while improving the safety of the traveling public during the winter months.


Assuntos
Acidentes de Trânsito , Tempo (Meteorologia) , Acidentes de Trânsito/prevenção & controle , Humanos , Segurança , Estações do Ano , Neve
4.
Int J Stroke ; 16(8): 944-952, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-33427104

RESUMO

BACKGROUND: The research about the influence of triglyceride-glucose index on early prognosis in stroke is lacking. AIMS: In this study, we evaluated the association between triglyceride-glucose index and early neurological deterioration in patients with single subcortical infarctions. METHODS: Consecutive patients with single subcortical infarctions within 72 h of symptom onset between 2011 and 2015. Early neurological deterioration was defined as an increase of ≥2 in the total NIHSS score or ≥1 in the motor NIHSS score. The triglyceride-glucose index was calculated using the log scale of fasting triglyceride (mg/dL) × fasting glucose (mg/dL)/2. RESULTS: A total of 305 patients with single subcortical infarctions were evaluated. In multivariable analysis, the triglyceride-glucose index (adjusted odds ratio [aOR] = 2.94, 95% confidence interval [CI] = 1.58-5.45) and age (aOR = 1.05, 95% CI = 1.01-1.09) were associated with early neurological deterioration. In subgroup analysis according to the type of single subcortical infarctions, only patients with proximal single subcortical infarctions showed a significant association between the triglyceride-glucose index and early neurological deterioration (aOR = 2.92, 95% CI = 1.35-6.29). On the other hand, there was no statistical significance in patients with distal single subcortical infarctions. Patients with untreated diabetes also showed the close association between the triglyceride-glucose index and early neurological deterioration (aOR = 3.94, 95% CI = 1.47-10.52). CONCLUSIONS: The triglyceride-glucose index was associated with early neurological deterioration in single subcortical infarctions. This association differed depending on the location of lesion and the presence of untreated diabetes.


Assuntos
Glucose , Acidente Vascular Cerebral , Infarto Cerebral , Humanos , Prognóstico , Fatores de Risco , Triglicerídeos
5.
Histopathology ; 77(3): 402-412, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32473032

RESUMO

AIMS: Histology-based tumour microenvironment (TME) scores are useful in predicting the prognosis of gastrointestinal cancer. However, their prognostic roles in distal bile duct cancer (DBDC) have not been previously studied. This study aimed to evaluate the prognostic significance of the TME scores using the Klintrup-Mäkinen (KM) grade, tumour stroma percentage (TSP) and the Glasgow microenvironment score (GMS) in resected DBDC. METHODS AND RESULTS: Eighty-one patients with DBDC who underwent curative resection were enrolled. DBDC was graded according to KM grade, TSP and GMS. A high KM grade was found in 19 patients (24%) and a high TSP was found in 47 patients (58%). A high TSP was significantly correlated with a low KM grade (P < 0.001). The distribution of the GMS, which was developed by combining the KM grade and TSP, was as follows: 0 (n = 19, 24%), 1 (n = 19, 24%) and 2 (n = 43, 52%). A low KM grade, high TSP and high GMS were significantly associated with short overall survival (OS) (P < 0.001) and relapse-free survival (RFS) (P < 0.001). Furthermore, multivariate analysis showed that a low KM grade [hazard ratio (HR) = 3.826; confidence interval (CI) = 1.650-8.869; P = 0.014], high TSP (HR = 2.193; CI = 1.173-4.100, P = 0.002) and high GMS (HR = 7.148; CI = 2.811-18.173) were independent prognostic factors for short RFS; a low KM grade (HR = 4.324; CI = 1.594-11.733) and high GMS (HR = 6.332; CI = 2.743-14.594) were independent prognostic factors for short OS. CONCLUSION: Histology-based TME scores, including the KM grade, TSP and GMS, are useful for predicting the survival of patients with resected DBDC.


Assuntos
Adenocarcinoma/patologia , Neoplasias dos Ductos Biliares/patologia , Gradação de Tumores/métodos , Microambiente Tumoral , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Prognóstico
7.
Respirology ; 23(3): 325-330, 2018 03.
Artigo em Inglês | MEDLINE | ID: mdl-28960643

RESUMO

BACKGROUND AND OBJECTIVE: Cryptogenic organizing pneumonia (COP) is corticosteroid responsive but residual computed tomography (CT) chest changes are often noted. The present study examined clinical and HRCT features of COP in which there was incomplete resolution. METHODS: We studied 93 patients with histopathologically confirmed COP and serial HRCT imaging. Clinical features were assessed, and serial CT images were analysed. Uni- and multivariate analyses were performed to determine clinical or imaging factors related to incomplete resolution on CT. RESULTS: Complete resolution on CT imaging was seen in 21/93 patients (23%) and residual abnormalities were seen in 72/93 patients (77%). In univariate analysis, total lesion (P = 0.036), degree of consolidation (P = 0.011), treatment duration (P < 0.001) and single-breath carbon monoxide diffusing capacity of lung (P = 0.021) were significantly associated with residual imaging abnormalities. In multivariate analysis, extent of consolidation (P = 0.018; odds ratio (OR) = 14.92) and treatment duration (P = 0.011; OR = 1.32) remained as significant factors linked to residual abnormalities. CT images in unresolved COP were akin to fibrotic non-specific interstitial pneumonia (fNSIP) in 53/72 (74%) patients. CONCLUSION: Clinical, radiological and lung diffusion measurements were related to incomplete resolution on CT after COP. Imaging abnormalities on CT chest generally resembled fNSIP.


Assuntos
Pneumonia em Organização Criptogênica/diagnóstico , Pulmão/diagnóstico por imagem , Radiografia Torácica/métodos , Tomografia Computadorizada por Raios X/métodos , Adulto , Idoso , Pneumonia em Organização Criptogênica/fisiopatologia , Progressão da Doença , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Prognóstico , Testes de Função Respiratória , Índice de Gravidade de Doença , Fatores de Tempo
8.
Cell Rep ; 18(3): 762-776, 2017 01 17.
Artigo em Inglês | MEDLINE | ID: mdl-28099853

RESUMO

Mammals have extremely limited regenerative capabilities; however, axolotls are profoundly regenerative and can replace entire limbs. The mechanisms underlying limb regeneration remain poorly understood, partly because the enormous and incompletely sequenced genomes of axolotls have hindered the study of genes facilitating regeneration. We assembled and annotated a de novo transcriptome using RNA-sequencing profiles for a broad spectrum of tissues that is estimated to have near-complete sequence information for 88% of axolotl genes. We devised expression analyses that identified the axolotl orthologs of cirbp and kazald1 as highly expressed and enriched in blastemas. Using morpholino anti-sense oligonucleotides, we find evidence that cirbp plays a cytoprotective role during limb regeneration whereas manipulation of kazald1 expression disrupts regeneration. Our transcriptome and annotation resources greatly complement previous transcriptomic studies and will be a valuable resource for future research in regenerative biology.


Assuntos
Extremidades/fisiologia , Transcriptoma , Ambystoma mexicanum , Animais , Hibridização In Situ , Proteínas de Ligação a Fator de Crescimento Semelhante a Insulina/antagonistas & inibidores , Proteínas de Ligação a Fator de Crescimento Semelhante a Insulina/genética , Proteínas de Ligação a Fator de Crescimento Semelhante a Insulina/metabolismo , RNA/química , RNA/metabolismo , Interferência de RNA , Splicing de RNA , RNA Interferente Pequeno/metabolismo , Proteínas de Ligação a RNA/genética , Proteínas de Ligação a RNA/metabolismo , Regeneração , Análise de Sequência de RNA
9.
PLoS Comput Biol ; 11(4): e1004203, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25879937

RESUMO

Pathogenic bacteria such as Listeria and Yersinia gain initial entry by binding to host target cells and stimulating their internalization. Bacterial uptake entails successive, increasingly strong associations between receptors on the surface of bacteria and hosts. Even with genetically identical cells grown in the same environment, there are vast differences in the number of bacteria entering any given cell. To gain insight into this variability, we examined uptake dynamics of Escherichia coli engineered to express the invasin surface receptor from Yersinia, which enables uptake via mammalian host ß1-integrins. Surprisingly, we found that the uptake probability of a single bacterium follows a simple power-law dependence on the concentration of integrins. Furthermore, the value of a power-law parameter depends on the particular host-bacterium pair but not on bacterial concentration. This power-law captures the complex, variable processes underlying bacterial invasion while also enabling differentiation of cell lines.


Assuntos
Bactérias/metabolismo , Bactérias/patogenicidade , Interações Hospedeiro-Patógeno/fisiologia , Proteínas de Membrana/metabolismo , Aderência Bacteriana , Infecções Bacterianas , Proteínas de Bactérias/metabolismo , Biologia Computacional , Células HeLa , Humanos , Modelos Biológicos
10.
Am J Hosp Palliat Care ; 32(3): 322-8, 2015 May.
Artigo em Inglês | MEDLINE | ID: mdl-24370716

RESUMO

Many geriatricians care for terminally ill and dying patients, but it is unclear whether the current geriatric medicine fellows receive sufficient training in hospice and palliative care (H&PC). A national cross-sectional survey was conducted between March and June 2011 to determine fellows' experience and perceived competency with H&PC. Fellows (143 of 298, 48%) and program directors (PDs; 69 of 150, 46%) answered the surveys on paper or online. Three-fourths of the fellows planned to practice H&PC; however, only 35% fellows versus 42% PDs believed that fellows were well prepared in this area. Factors associated with fellows' self-reported better preparation included completion of an H&PC rotation, experiences with an inpatient hospice facility, inpatient palliative care consulting service, and the presence of a formal H&PC curriculum.


Assuntos
Bolsas de Estudo , Geriatria/educação , Cuidados Paliativos na Terminalidade da Vida/organização & administração , Cuidados Paliativos/organização & administração , Atitude do Pessoal de Saúde , Competência Clínica , Estudos Transversais , Humanos
12.
J Immunol ; 192(10): 4655-65, 2014 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-24729611

RESUMO

In murine schistosomiasis, immunopathology and cytokine production in response to parasite eggs are uneven and strain dependent. CBA/J (CBA) mice develop severe hepatic granulomatous inflammation associated with prominent Th17 cell responses driven by dendritic cell (DC)-derived IL-1ß and IL-23. Such Th17 cells fail to develop in low-pathology C57BL/6 (BL/6) mice, and the reasons for these strain-specific differences in APC reactivity to eggs remain unclear. We show by gene profiling that CBA DCs display an 18-fold higher expression of the C-type lectin receptor CD209a, a murine homolog of human DC-specific ICAM-3-grabbing nonintegrin, compared with BL/6 DCs. Higher CD209a expression was observed in CBA splenic and granuloma APC subpopulations, but only DCs induced Th17 cell differentiation in response to schistosome eggs. Gene silencing in CBA DCs and overexpression in BL/6 DCs demonstrated that CD209a is essential for egg-elicited IL-1ß and IL-23 production and subsequent Th17 cell development, which is associated with SRC, RAF-1, and ERK1/2 activation. These findings reveal a novel mechanism controlling the development of Th17 cell-mediated severe immunopathology in helminthic disease.


Assuntos
Moléculas de Adesão Celular/imunologia , Células Dendríticas/imunologia , Regulação da Expressão Gênica/imunologia , Lectinas Tipo C/imunologia , Receptores de Superfície Celular/imunologia , Schistosoma/imunologia , Esquistossomose/imunologia , Células Th17/imunologia , Animais , Moléculas de Adesão Celular/biossíntese , Moléculas de Adesão Celular/genética , Linhagem Celular , Células Dendríticas/metabolismo , Células Dendríticas/patologia , Ativação Enzimática/genética , Ativação Enzimática/imunologia , Feminino , Regulação da Expressão Gênica/genética , Inativação Gênica/imunologia , Granuloma/genética , Granuloma/imunologia , Granuloma/patologia , Humanos , Interleucina-1beta/genética , Interleucina-1beta/imunologia , Interleucina-1beta/metabolismo , Interleucina-23/genética , Interleucina-23/imunologia , Interleucina-23/metabolismo , Lectinas Tipo C/biossíntese , Lectinas Tipo C/genética , Sistema de Sinalização das MAP Quinases/genética , Sistema de Sinalização das MAP Quinases/imunologia , Camundongos , Camundongos Endogâmicos CBA , Proteína Quinase 3 Ativada por Mitógeno/genética , Proteína Quinase 3 Ativada por Mitógeno/imunologia , Proteína Quinase 3 Ativada por Mitógeno/metabolismo , Proteínas Proto-Oncogênicas c-raf/genética , Proteínas Proto-Oncogênicas c-raf/imunologia , Proteínas Proto-Oncogênicas c-raf/metabolismo , Proteínas Proto-Oncogênicas pp60(c-src)/genética , Proteínas Proto-Oncogênicas pp60(c-src)/imunologia , Proteínas Proto-Oncogênicas pp60(c-src)/metabolismo , Receptores de Superfície Celular/biossíntese , Receptores de Superfície Celular/genética , Schistosoma/genética , Schistosoma/metabolismo , Esquistossomose/genética , Esquistossomose/metabolismo , Esquistossomose/patologia , Baço/imunologia , Baço/metabolismo , Baço/patologia , Células Th17/metabolismo , Células Th17/patologia
13.
G3 (Bethesda) ; 4(1): 109-16, 2014 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-24281423

RESUMO

Recent studies have shown that proximal arrangement of multiple genes can have complex effects on gene expression. For example, in the case of heterologous gene expression modules, certain arrangements of the selection marker and the gene expression cassette may have unintended consequences that limit the predictability and interpretability of module behaviors. The relationship between arrangement and expression has not been systematically characterized within heterologous modules to date. In this study, we quantitatively measured gene expression patterns of the selection marker (KlURA3 driven by the promoter, pKlURA) and the gene expression cassette (GFP driven by the galactose-inducible GAL1 promoter, pGAL1) in all their possible relative arrangements in Saccharomyces cerevisiae. First, we observed that pKlURA activity depends strongly on the relative arrangement and the activity of pGAL1. Most notably, we observed transcriptional suppression in the case of divergent arrangements: pKlURA activity was reduced when pGAL1 was inactive. Based on our nucleosome occupancy data, we attribute the observed transcriptional reduction to nucleosome repositioning. Second, we observed that pGAL1 activity also depends on the relative arrangement of pKlURA. In particular, strains with divergent promoters showed significantly different pGAL1 activation patterns from other strains, but only when their growth was compromised by lack of uracil. We reasoned that this difference in pGAL1 activation patterns arises from arrangement-dependent pKlURA activity that can affect the overall cell physiology (i.e., cell growth and survival in the uracil-depleted condition). Our results underscore the necessity to consider ramifications of promoter arrangement when using synthetic gene expression modules.


Assuntos
Genes Fúngicos , Saccharomyces cerevisiae/genética , Galactoquinase/genética , Galactoquinase/metabolismo , Regulação Fúngica da Expressão Gênica , Genes Reporter , Nucleossomos/metabolismo , Regiões Promotoras Genéticas , Saccharomyces cerevisiae/citologia , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo
14.
Curr Med Chem ; 20(31): 3872-902, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23848535

RESUMO

In 1977 an unknown natural product was isolated from Streptomyces staurosporeus by Omura et al. during a search for new alkaloids present in actinomycetes and was given the name AM-2282. Later, the structure of AM-2282 was elucidated by single crystal X-ray analysis and renamed as staurosporine. It has been published that staurosporine and its analogues display strong inhibitory effect against a variety of kinases and a number of biological properties such as antifungal, antibacterial, and immunosuppressive activities. Despite strong inhibitory activity of staurosporine, a very high level of cross-reactivity makes it impossible to use staurosporine as a therapeutic agent. In the course of searching for other staurosporine-related compounds, a number of staurosporine analogues have been isolated from different microorganisms. In addition, a number of staurosporine analogues have been synthesized to improve the poor selectivity and target specificity of staurosporine which limited its clinical effectiveness. The review addresses staurosporine analogues from both microbial and synthetic sources and their biological activities.


Assuntos
Indóis/farmacologia , Inibidores de Proteínas Quinases/farmacologia , Animais , Humanos , Indóis/química , Inibidores de Proteínas Quinases/química
15.
Methods ; 62(1): 109-20, 2013 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-23563144

RESUMO

We provide a guide to performing a sensitivity analysis (SA) of quantitative models of gene expression dynamics appropriate to the levels of uncertainty in the model: spanning cases where parameters are relatively well-constrained to cases where they are poorly constrained. In the well-constrained case, we present methods to perform "local" SA (LSA), which considers small perturbations for a single set of model parameter values. In the poorly-constrained case, we present methods to perform "global" SA (GSA) as a means to evaluate the sensitivity of a model over large regions of parameter space. We apply these methods to quantitative models of increasing complexity. The models we consider are simple logistic growth, negative feedback in a mRNA-protein model, and two models of decision making within bacteriophage λ. We discuss the best practices for how SA can be utilized in an iterative fashion to advance biological understanding.


Assuntos
Bacteriófago lambda/genética , Regulação Viral da Expressão Gênica , Modelos Genéticos , RNA Mensageiro/genética , Software , Proteínas Virais/genética , Bacteriófago lambda/metabolismo , Interpretação Estatística de Dados , Escherichia coli/virologia , Retroalimentação Fisiológica , Lisogenia/genética , RNA Mensageiro/metabolismo , Sensibilidade e Especificidade , Incerteza , Proteínas Virais/metabolismo
16.
BMC Ear Nose Throat Disord ; 12: 5, 2012 Jun 06.
Artigo em Inglês | MEDLINE | ID: mdl-22672326

RESUMO

BACKGROUND: The 5 G/5 G genotype of PAI-1 polymorphism is linked to decreased plasminogen activator inhibitor-1 (PAI-1) levels and it has been suggested that lower PAI-1 levels may provide protective effects on inflammation, local microcirculatory disturbance, and fibrotic changes, which are likely associated with development of sudden sensorineural hearing loss (SSNHL). METHODS: The association of the 4 G/5 G PAI-1 polymorphism with the development and clinical outcome of SSNHL is evaluated via a case control study. 103 patients with SSNHL and 113 age and sex-matched controls were enrolled at University of Ferrara, Italy and hearing loss outcome was measured at least 3 months after the onset of hearing loss. DNA was isolated from peripheral blood using the QIAamp kit and the 4 G/5 G polymorphism in the -675 promoter region was genotyped with an allele-specific PCR. Genotype distribution was tested in patients and compared to controls by chi-square and odd-ratio analysis. The codominant and recessive models were used for the multiple logistic regression analyses of the PAI-1 gene allele. RESULTS: In this population, 5 G/5 G genotype had a two-time lower frequency in SSNHL patients compared to healthy controls (15.5% vs 30.1%) and was associated with decreased odds compared to 4 G/5 G genotype (OR 0.37, 95% CI 0.19-0.75, p = 0.005). In addition, the patients with 5 G/5 G genotype showed a trend of more than 2 times higher ratio of hearing recovery (> 20 dB) after systemic corticosteroid treatment compared to 4 G/5 G genotype (OR 2.3, 95% CI 0.32 - 16.83, p = 0.39), suggesting a better clinical outcome. CONCLUSIONS: The 5 G/5 G genotype of PAI-1 may be associated with a reduced risk of SSNHL in the Italian population.

17.
Am J Reprod Immunol ; 65(3): 317-24, 2011 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-21223426

RESUMO

Despite tremendous regional and subregional disparities in HIV prevalence around the world, epidemiology consistently demonstrates that black communities have been disproportionately affected by the pandemic. There are many reasons for this, and a narrow focus on socio-behavioural causes may be seen as laying blame on affected communities or individuals. HIV sexual transmission is very inefficient, and a number of biological factors are critical in determining whether an unprotected sexual exposure to HIV results in productive infection. This review will focus on ways in which biology, rather than behaviour, may contribute to regional and racial differences in HIV epidemic spread. Specific areas of focus are viral factors, host genetics, and the impact of co-infections and host immunology. Considering biological causes for these racial disparities may help to destigmatize the issue and lead to new and more effective strategies for prevention.


Assuntos
Infecções por HIV/epidemiologia , Infecções por HIV/transmissão , HIV-1 , Disparidades nos Níveis de Saúde , África , População Negra/estatística & dados numéricos , Feminino , Predisposição Genética para Doença , Geografia , Infecções por HIV/complicações , Infecções por HIV/virologia , HIV-1/fisiologia , Humanos , Imunidade Inata/genética , Imunidade nas Mucosas , Infecções/complicações , Masculino , Saúde das Minorias , Prevalência , Grupos Raciais/genética , Fatores de Risco
18.
ACS Nano ; 4(10): 5721-30, 2010 Oct 26.
Artigo em Inglês | MEDLINE | ID: mdl-20836500

RESUMO

We investigate surface-enhanced Raman scattering (SERS) from gold-coated silicon-germanium nanocone substrates that are decorated with 30-nm spherical gold nanoparticles (AuNPs). Finite-element simulations suggest that individual nanocones generate stronger electromagnetic enhancement with axial polarization (i.e., polarization parallel to the vertical axis of the nanocones) than with transverse polarization (i.e., polarization in the plane of the nanocone substrate), whereas the excitation in a typical Raman microscope is mainly polarized in the transverse plane. We introduce a practical approach to improve the SERS performance of the substrate by filling the valleys between nanocones with AuNPs. Simulations reveal an enhanced electric field at the nanoscale junctions formed between AuNPs and nanocones, and we explain this lateral coupling with a hybridization model for a particle-film system. We further experimentally verify the added enhancement by measuring SERS from trans-1,2-bi-(4-pyridyl) ethylene molecules absorbed onto the substrates. We report over one order-of-magnitude increase in SERS activities with the AuNP decoration (compared to the nanocone substrate without AuNPs) and achieve a spatially averaged enhancement factor of 1.78 × 10(8) at 785-nm excitation. Understanding and implementing the enhancing mechanism of structured metallic surfaces decorated with plasmonic nanoparticles open possibilities to substantially improve the SERS performance of the existing process-engineered substrates.


Assuntos
Nanopartículas Metálicas/química , Análise Espectral Raman/métodos , Simulação por Computador , Análise de Elementos Finitos , Ouro/química , Teste de Materiais , Microscopia de Força Atômica/métodos , Microscopia Eletrônica de Varredura/métodos , Reprodutibilidade dos Testes , Espalhamento de Radiação
19.
PLoS Biol ; 8(9)2010 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-20877711

RESUMO

The transition of the mammalian cell from quiescence to proliferation is a highly variable process. Over the last four decades, two lines of apparently contradictory, phenomenological models have been proposed to account for such temporal variability. These include various forms of the transition probability (TP) model and the growth control (GC) model, which lack mechanistic details. The GC model was further proposed as an alternative explanation for the concept of the restriction point, which we recently demonstrated as being controlled by a bistable Rb-E2F switch. Here, through a combination of modeling and experiments, we show that these different lines of models in essence reflect different aspects of stochastic dynamics in cell cycle entry. In particular, we show that the variable activation of E2F can be described by stochastic activation of the bistable Rb-E2F switch, which in turn may account for the temporal variability in cell cycle entry. Moreover, we show that temporal dynamics of E2F activation can be recast into the frameworks of both the TP model and the GC model via parameter mapping. This mapping suggests that the two lines of phenomenological models can be reconciled through the stochastic dynamics of the Rb-E2F switch. It also suggests a potential utility of the TP or GC models in defining concise, quantitative phenotypes of cell physiology. This may have implications in classifying cell types or states.


Assuntos
Ciclo Celular , Fatores de Transcrição E2F/metabolismo , Modelos Biológicos , Processos Estocásticos , Animais , Western Blotting , Linhagem Celular , Citometria de Fluxo , Ratos
20.
Tissue Eng Part A ; 16(9): 2871-81, 2010 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-20412030

RESUMO

Skeletal muscle injury resulting in tissue loss poses unique challenges for surgical repair. Despite the regenerative potential of skeletal muscle, if a significant amount of tissue is lost, skeletal myofibers will not grow to fill the injured area completely. Prior work in our lab has shown the potential to fill the void with an extracellular matrix (ECM) scaffold, resulting in restoration of morphology, but not functional recovery. To improve the functional outcome of the injured muscle, a muscle-derived ECM was implanted into a 1 x 1 cm(2), full-thickness defect in the lateral gastrocnemius (LGAS) of Lewis rats. Seven days later, bone-marrow-derived mesenchymal stem cells (MSCs) were injected directly into the implanted ECM. Partial functional recovery occurred over the course of 42 days when the LGAS was repaired with an MSC-seeded ECM producing 85.4 +/- 3.6% of the contralateral LGAS. This was significantly higher than earlier recovery time points (p < 0.05). The specific tension returned to 94 +/- 9% of the contralateral limb. The implanted MSC-seeded ECM had more blood vessels and regenerating skeletal myofibers than the ECM without cells (p < 0.05). The data suggest that the repair of a skeletal muscle defect injury by the implantation of a muscle-derived ECM seeded with MSCs can improve functional recovery after 42 days.


Assuntos
Células da Medula Óssea/citologia , Matriz Extracelular/química , Transplante de Células-Tronco Mesenquimais/métodos , Músculo Esquelético/citologia , Músculo Esquelético/lesões , Músculo Esquelético/cirurgia , Engenharia Tecidual/métodos , Animais , Desmina/metabolismo , Imuno-Histoquímica , Masculino , Miogenina/metabolismo , Ratos
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