963 resultados para 860[2].09


Relevância:

80.00% 80.00%

Publicador:

Resumo:

Background: Altered deposition of extracellular matrix (ECM) in the airway smooth muscle (ASM) layer as observed in asthma may influence ASM mechanical properties. We hypothesized that ECM in ASM is associated with airway function in asthma. First, we investigated the difference in ECM expression in ASM between asthma and controls. Second, we examined whether ECM expression is associated with bronchoconstriction and bronchodilation in vivo. Methods: Our cross-sectional study comprised 19 atopic mild asthma patients, 15 atopic and 12 nonatopic healthy subjects. Spirometry, methacholine responsiveness, deep-breath-induced bronchodilation (Delta R-rs) and bronchoscopy with endobronchial biopsies were performed. Positive staining of elastin, collagen I, III and IV, decorin, versican, fibronectin, laminin and tenascin in ASM was quantified as fractional area and mean density. Data were analysed using Pearson's or Spearman's correlation coefficient. Results: Extracellular matrix expression in ASM was not different between asthma and controls. In asthmatics, fractional area and mean density of collagen I and III were correlated with methacholine dose-response slope and DRrs, respectively (r = 0.71, P < 0.01; r = 0.60, P = 0.02). Furthermore, ASM collagen III and laminin in asthma were correlated with FEV1 reversibility (r = -0.65, P = 0.01; r = -0.54, P = 0.04). Conclusion: In asthma, ECM in ASM is related to the dynamics of airway function in the absence of differences in ECM expression between asthma and controls. This indicates that the ASM layer in its full composition is a major structural component in determining variable airways obstruction in asthma.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

Serracutisoma proximum is a harvestman with alternative male morphs. Large males use sexually dimorphic second legs in fights for the possession of territories on the vegetation, where females oviposit. Small males have short second legs and do not fight but rather sneak into the territories and copulate with egg-guarding females. We investigated the presence of male dimorphism across 10 populations of S. proximum, compared gonadal investment between male morphs, and assessed if the distribution of the sneakers is influenced by harem size. In all populations, there was male dimorphism, indicated by the bimodal distribution of the leg II length/body length. Gonadal investment did not differ between morphs and was not affected by male size, second leg length, and morph relative frequency in the populations. We found 361 territories, 90.0% containing 1 male, 9.7% containing 2 males (dyads), and 0.3% containing 3 males. The probability of encountering dyads increased with the number of females present in the territories. Moreover, the proportion of sneakers in territories containing dyads was higher than would be expected by chance. One possible reason for the ubiquity of alternative morphs in S. proximum could be the high mating opportunities experienced by sneakers in spatially structured populations with a resource defense polygyny system. Additionally, the high frequency of successful invasions by sneakers and hence the high sperm competition risk for both morphs may explain the similarity in gonadal investment between male morphs.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

Soft-sediment deformation (SSD) is widely described in the literature, but there is no clear consensus regarding its origin and significance. Existing models for SSD in fluvial sediments do not clearly demonstrate a relationship between the structures, preserved facies expression, and larger-scale depositional architecture. In this study several types of SSD structures are recorded in Cambrian fluvial deposits and these occur interbedded with undeformed strata throughout the entire stratigraphic interval. The random distribution of these features in relation to primary facies types and fluvial forms indicates that they have neither a direct nor indirect relationship with any depositional processes or bedform type. We propose that the relationship of SSD at the bed-set-scale to larger-scale depositional architecture, combined with tectono-stratigraphic analysis allows the determination of both short-term fluvial hydraulic conditions in ancient stream systems, such as the nature of the flow regime responsible for depositing ancient fluvial stream successions, and the long-term subsidence rates, in the form of mean recurrence interval of the seismic events responsible for triggering the generation of SSD in tectonically active basins. (c) 2012 Elsevier B.V. All rights reserved.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

The study was conducted at the Research Laboratory of Hydraulic and Irrigation Group in the Rural Engineering Department, Technical University of Madrid (Universidad Politecnica de Madrid), Madrid, Spain. Water temperatures of 20, 30, 40 degrees C and system pressures often encountered in irrigation practices of 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190 and 200 k Pa were applied to determine the effects of different water temperatures and pressures on emitter discharge. Non-pressure compensating in-line emitter which has turbulent flow regime with a long-path (labyrinth), emitter discharge was 4 L h(-1) at system pressure of 100 kPa according to the manufacturer recommended, was used. Emitters were spaced 20 cm along the drip laterals with 16 mm diameter. Discharge equations and coefficients of variation related to temperatures of 20, 30 and 40 degrees C were obtained as q = 0.375H(0.51), q = 0.358H(0.52), q = 0.346H(0.53) and 2.68, 2.09, 3.65, respectively. Discharge of the emitter was affected by different system pressures and increased as potentially (R = 0993-0996). In general. the emitter discharge increased with increasing temperature. However, especially in the common system pressures of 90-120 k Pa, differences of obtained emitter discharges between the different water temperatures were not significant (1%).

Relevância:

80.00% 80.00%

Publicador:

Resumo:

Background Vitamin D transcriptional effects were linked to tumor growth control, however, the hormone targets were determined in cell cultures exposed to supra physiological concentrations of 1,25(OH)2D3 (50-100nM). Our aim was to evaluate the transcriptional effects of 1,25(OH)2D3 in a more physiological model of breast cancer, consisting of fresh tumor slices exposed to 1,25(OH)2D3 at concentrations that can be attained in vivo. Methods Tumor samples from post-menopausal breast cancer patients were sliced and cultured for 24 hours with or without 1,25(OH)2D3 0.5nM or 100nM. Gene expression was analyzed by microarray (SAM paired analysis, FDR≤0.1) or RT-qPCR (p≤0.05, Friedman/Wilcoxon test). Expression of candidate genes was then evaluated in mammary epithelial/breast cancer lineages and cancer associated fibroblasts (CAFs), exposed or not to 1,25(OH)2D3 0.5nM, using RT-qPCR, western blot or immunocytochemistry. Results 1,25(OH)2D3 0.5nM or 100nM effects were evaluated in five tumor samples by microarray and seven and 136 genes, respectively, were up-regulated. There was an enrichment of genes containing transcription factor binding sites for the vitamin D receptor (VDR) in samples exposed to 1,25(OH)2D3 near physiological concentration. Genes up-modulated by both 1,25(OH)2D3 concentrations were CYP24A1, DPP4, CA2, EFTUD1, TKTL1, KCNK3. Expression of candidate genes was subsequently evaluated in another 16 samples by RT-qPCR and up-regulation of CYP24A1, DPP4 and CA2 by 1,25(OH)2D3 was confirmed. To evaluate whether the transcripitonal targets of 1,25(OH)2D3 0.5nM were restricted to the epithelial or stromal compartments, gene expression was examined in HB4A, C5.4, SKBR3, MDA-MB231, MCF-7 lineages and CAFs, using RT-qPCR. In epithelial cells, there was a clear induction of CYP24A1, CA2, CD14 and IL1RL1. In fibroblasts, in addition to CYP24A1 induction, there was a trend towards up-regulation of CA2, IL1RL1, and DPP4. A higher protein expression of CD14 in epithelial cells and CA2 and DPP4 in CAFs exposed to 1,25(OH)2D3 0.5nM was detected. Conclusions In breast cancer specimens a short period of 1,25(OH)2D3 exposure at near physiological concentration modestly activates the hormone transcriptional pathway. Induction of CYP24A1, CA2, DPP4, IL1RL1 expression appears to reflect 1,25(OH)2D3 effects in epithelial as well as stromal cells, however, induction of CD14 expression is likely restricted to the epithelial compartment.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

La nanotecnologia è una scienza innovativa che sviluppa e utilizza materiali di dimensioni nanometriche (< 100 nm). Lo sviluppo e il mercato delle nanoparticelle in merito alle loro interessanti proprietà chimico‐fisiche, é accompagnato da una scarsa conoscenza relativa al destino finale e agli effetti che questi nano materiali provocano nell’ ambiente [Handy et al., 2008]. La metodologia LCA (Life Cycle Assessment – Valutazione del Ciclo di Vita) è riconosciuta come lo strumento ideale per valutare e gestire gli impatti ambientali indotti dalle ENPs, nonostante non sia ancora possibile definire, in maniera precisa, un Fattore di Caratterizzazione CF per questa categoria di sostanze. Il lavoro di questa tesi ha l’obbiettivo di stimare il Fattore di Effetto EF per nanoparticelle di Diossido di Titanio (n‐TiO2) e quindi contribuire al calcolo del CF; seguendo il modello di caratterizzazione USEtox, l’EF viene calcolato sulla base dei valori di EC50 o LC50 relativi agli organismi appartenenti ai tre livelli trofici di un ecosistema acquatico (alghe, crostacei, pesci) e assume valore pari a 49,11 PAF m3/Kg. I valori tossicologici utilizzati per il calcolo del Fattore di Effetto derivano sia da un’accurata ricerca bibliografica sia dai risultati ottenuti dai saggi d’inibizione condotti con n‐TiO2 sulla specie algale Pseudokirchneriella Subcapitata. La lettura dei saggi è stata svolta applicando tre differenti metodi quali la conta cellulare al microscopio ottico (media geometrica EC50: 2,09 mg/L, (I.C.95% 1,45‐ 2,99)), l’assorbanza allo spettrofotometro (strumento non adatto alla lettura di test condotti con ENPs) e l’intensità di fluorescenza allo spettrofluorimetro (media geometrica EC50: 3,67 mg/L (I.C.95% 2,16‐6,24)), in modo tale da confrontare i risultati e valutare quale sia lo strumento più consono allo studio di saggi condotti con n‐TiO2. Nonostante la grande variabilità dei valori tossicologici e la scarsa conoscenza sui meccanismi di tossicità delle ENPs sulle specie algali, il lavoro sperimentale e la ricerca bibliografica condotta, hanno permesso di individuare alcune proprietà chimico‐fisiche delle nanoparticelle di Diossido di Titanio che sembrano essere rilevanti per la loro tossicità come la fase cristallina, le dimensioni e la foto attivazione [Vevers et al., 2008; Reeves et al., 2007]. Il lavoro sperimentale ha inoltre permesso di ampliare l’insieme di valori di EC50 finora disponibile in letteratura e di affiancare un progetto di ricerca dottorale utilizzando il Fattore di Effetto per n‐ TiO2 nel calcolo del Fattore di Caratterizzazione.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

Background: Body mass index (BMI) is a risk factor for endometrial cancer. We quantified the risk and investigated whether the association differed by use of hormone replacement therapy (HRT), menopausal status, and histologic type. Methods: We searched MEDLINE and EMBASE (1966 to December 2009) to identify prospective studies of BMI and incident endometrial cancer. We did random-effects meta-analyses, meta-regressions, and generalized least square regressions for trend estimations assuming linear, and piecewise linear, relationships. Results: Twenty-four studies (17,710 cases) were analyzed; 9 studies contributed to analyses by HRT, menopausal status, or histologic type, all published since 2003. In the linear model, the overall risk ratio (RR) per 5 kg/m2 increase in BMI was 1.60 (95% CI, 1.52–1.68), P < 0.0001. In the piecewise model, RRs compared with a normal BMI were 1.22 (1.19–1.24), 2.09 (1.94–2.26), 4.36 (3.75–5.10), and 9.11 (7.26–11.51) for BMIs of 27, 32, 37, and 42 kg/m2, respectively. The association was stronger in never HRT users than in ever users: RRs were 1.90 (1.57–2.31) and 1.18 (95% CI, 1.06–1.31) with P for interaction ¼ 0.003. In the piecewise model, the RR in never users was 20.70 (8.28–51.84) at BMI 42 kg/m2, compared with never users at normal BMI. The association was not affected by menopausal status (P ¼ 0.34) or histologic type (P ¼ 0.26). Conclusions: HRT use modifies the BMI-endometrial cancer risk association. Impact: These findings support the hypothesis that hyperestrogenia is an important mechanism underlying the BMI-endometrial cancer association, whilst the presence of residual risk in HRT users points to the role of additional systems. Cancer Epidemiol Biomarkers Prev; 19(12); 3119–30.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

We aimed to evaluate whether carotid intima-media thickness (CIMT) or the presence of plaque can confer additional predictive value of future cardiovascular (CV) ischemic events in patients with pre-existing atherosclerotic vascular disease. We identified 2317 patients enrolled in the REduction of Atherothrombosis for Continued Health (REACH) registry who had atherosclerotic vascular disease and baseline CIMT measurements. The entire range of CIMT was divided into quartiles and the fourth quartile (? 1.5 mm) was defined as carotid plaque. Mean ± standard deviation baseline CIMT was 1.31 ± 0.65 mm. Associated CV ischemic events and vascular-related hospitalizations were evaluated over a 2-year follow-up. There was a positive increase in adjusted hazard ratios (HRs) for all-cause mortality (p = 0.04 for trend) and the quadruple endpoint (CV death, myocardial infarction (MI), stroke, hospitalization for CV events) with increasing quartiles of CIMT (p = 0.0008 for trend), which was mainly driven by the fourth quartile (carotid plaque). HRs for all-cause mortality, CV death, CV death/MI/stroke and the quadruple endpoint comparing the highest (carotid plaque) with the lowest CIMT quartile were 2.09 (95% CI, 1.07-4.10; p = 0.03); 2.49 (1.10-5.67; p = 0.03); 1.71 (1.10-2.67; p = 0.02); and 1.73 (1.31-2.27; p = 0.0001). In conclusion, our analyses suggest that the presence of carotid plaque, rather than the thickness of intima-media, appears to be associated with increased risk of CV morbidity and mortality, but confirmation of these findings in other population and prospective studies is required.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

Background Replicative phenotypic HIV resistance testing (rPRT) uses recombinant infectious virus to measure viral replication in the presence of antiretroviral drugs. Due to its high sensitivity of detection of viral minorities and its dissecting power for complex viral resistance patterns and mixed virus populations rPRT might help to improve HIV resistance diagnostics, particularly for patients with multiple drug failures. The aim was to investigate whether the addition of rPRT to genotypic resistance testing (GRT) compared to GRT alone is beneficial for obtaining a virological response in heavily pre-treated HIV-infected patients. Methods Patients with resistance tests between 2002 and 2006 were followed within the Swiss HIV Cohort Study (SHCS). We assessed patients' virological success after their antiretroviral therapy was switched following resistance testing. Multilevel logistic regression models with SHCS centre as a random effect were used to investigate the association between the type of resistance test and virological response (HIV-1 RNA <50 copies/mL or ≥1.5log reduction). Results Of 1158 individuals with resistance tests 221 with GRT+rPRT and 937 with GRT were eligible for analysis. Overall virological response rates were 85.1% for GRT+rPRT and 81.4% for GRT. In the subgroup of patients with >2 previous failures, the odds ratio (OR) for virological response of GRT+rPRT compared to GRT was 1.45 (95% CI 1.00-2.09). Multivariate analyses indicate a significant improvement with GRT+rPRT compared to GRT alone (OR 1.68, 95% CI 1.31-2.15). Conclusions In heavily pre-treated patients rPRT-based resistance information adds benefit, contributing to a higher rate of treatment success.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

Epidemiological data on snoring from preschool children are scarce, although habitual snoring (snoring on almost all nights) has been associated with poor long-term outcomes. In a population survey of 6,811 children aged 1-4 yrs (from Leicestershire, UK) the present authors determined prevalence, severity and risk factors for snoring, especially habitual snoring. In 59.7% of the children, parents reported snoring in the previous 12 months, including 7.9% with habitual snoring and 0.9% with habitual snoring and sleep disturbance. Prevalence of habitual snoring increased with age from 6.6% in 1-yr-olds to 13.0% in 4-yr-olds. Habitual snoring was associated with: one and both parents smoking (adjusted odds ratio (OR) 1.46 and 2.09, respectively); road traffic (OR 1.23); single parent (OR 1.60); and in White but not South Asian children, socioeconomic deprivation (OR 1.25 and 2.03 for middle and upper thirds of Townsend score, respectively). Respiratory tract symptoms related to atopic disorders and to respiratory infections were strongly associated with snoring; however, body mass index was not. In conclusion, habitual snoring is common in preschool children with one-third of cases attributable to avoidable risk factors. The strong association with atopic disorders, viral infections and environmental exposures suggests a complex aetiology, based on a general vulnerability of the respiratory tract.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

BACKGROUND: Not all clinical trials are published, which may distort the evidence that is available in the literature. We studied the publication rate of a cohort of clinical trials and identified factors associated with publication and nonpublication of results. METHODS: We analysed the protocols of randomized clinical trials of drug interventions submitted to the research ethics committee of University Hospital (Inselspital) Bern, Switzerland from 1988 to 1998. We identified full articles published up to 2006 by searching the Cochrane CENTRAL database (issue 02/2006) and by contacting investigators. We analyzed factors associated with the publication of trials using descriptive statistics and logistic regression models. RESULTS: 451 study protocols and 375 corresponding articles were analyzed. 233 protocols resulted in at least one publication, a publication rate of 52%. A total of 366 (81%) trials were commercially funded, 47 (10%) had non-commercial funding. 346 trials (77%) were multi-centre studies and 272 of these (79%) were international collaborations. In the adjusted logistic regression model non-commercial funding (Odds Ratio [OR] 2.42, 95% CI 1.14-5.17), multi-centre status (OR 2.09, 95% CI 1.03-4.24), international collaboration (OR 1.87, 95% CI 0.99-3.55) and a sample size above the median of 236 participants (OR 2.04, 95% CI 1.23-3.39) were associated with full publication. CONCLUSIONS: In this cohort of applications to an ethics committee in Switzerland, only about half of clinical drug trials were published. Large multi-centre trials with non-commercial funding were more likely to be published than other trials, but most trials were funded by industry.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

The need for a stronger and more durable building material is becoming more important as the structural engineering field expands and challenges the behavioral limits of current materials. One of the demands for stronger material is rooted in the effects that dynamic loading has on a structure. High strain rates on the order of 101 s-1 to 103 s-1, though a small part of the overall types of loading that occur anywhere between 10-8 s-1 to 104 s-1 and at any point in a structures life, have very important effects when considering dynamic loading on a structure. High strain rates such as these can cause the material and structure to behave differently than at slower strain rates, which necessitates the need for the testing of materials under such loading to understand its behavior. Ultra high performance concrete (UHPC), a relatively new material in the U.S. construction industry, exhibits many enhanced strength and durability properties compared to the standard normal strength concrete. However, the use of this material for high strain rate applications requires an understanding of UHPC’s dynamic properties under corresponding loads. One such dynamic property is the increase in compressive strength under high strain rate load conditions, quantified as the dynamic increase factor (DIF). This factor allows a designer to relate the dynamic compressive strength back to the static compressive strength, which generally is a well-established property. Previous research establishes the relationships for the concept of DIF in design. The generally accepted methodology for obtaining high strain rates to study the enhanced behavior of compressive material strength is the split Hopkinson pressure bar (SHPB). In this research, 83 Cor-Tuf UHPC specimens were tested in dynamic compression using a SHPB at Michigan Technological University. The specimens were separated into two categories: ambient cured and thermally treated, with aspect ratios of 0.5:1, 1:1, and 2:1 within each category. There was statistically no significant difference in mean DIF for the aspect ratios and cure regimes that were considered in this study. DIF’s ranged from 1.85 to 2.09. Failure modes were observed to be mostly Type 2, Type 4, or combinations thereof for all specimen aspect ratios when classified according to ASTM C39 fracture pattern guidelines. The Comite Euro-International du Beton (CEB) model for DIF versus strain rate does not accurately predict the DIF for UHPC data gathered in this study. Additionally, a measurement system analysis was conducted to observe variance within the measurement system and a general linear model analysis was performed to examine the interaction and main effects that aspect ratio, cannon pressure, and cure method have on the maximum dynamic stress.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

Melatonin has previously been suggested to affect hemostatic function but studies on the issue are scant. We hypothesized that, in humans, oral administration of melatonin is associated with decreased plasma levels of procoagulant hemostatic measures compared with placebo medication and that plasma melatonin concentration shows an inverse association with procoagulant measures. Forty-six healthy men (mean age 25 +/- 4 yr) were randomized, single-blinded, to either 3 mg of oral melatonin (n = 25) or placebo medication (n = 21). One hour thereafter, levels of melatonin, fibrinogen, and D-dimer as well as activities of coagulation factor VII (FVII:C) and VIII (FVIII:C) were measured in plasma. Multivariate analysis of covariance and regression analysis controlled for age, body mass index, mean arterial blood pressure, heart rate, and norepinephrine plasma level. Subjects on melatonin had significantly lower mean levels of FVIII:C (81%, 95% CI 71-92 versus 103%, 95% CI 90-119; P = 0.018) and of fibrinogen (1.92 g/L, 95% CI 1.76-2.08 versus 2.26 g/L, 95% CI 2.09-2.43; P = 0.007) than those on placebo explaining 14 and 17% of the respective variance. In all subjects, increased plasma melatonin concentration independently predicted lower levels of FVIII:C (P = 0.037) and fibrinogen (P = 0.022) explaining 9 and 11% of the respective variance. Melatonin medication and plasma concentration were not significantly associated with FVII:C and D-dimer levels. A single dose of oral melatonin was associated with lower plasma levels of procoagulant factors 60 min later. There might be a dose-response relationship between the plasma concentration of melatonin and coagulation activity.