946 resultados para Heurística surrogate


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The kinesin spindle protein (KSP), a member of the kinesin superfamily of microtubule-based motors, plays a critical role in mitosis as it mediates centrosome separation and bipolar spindle assembly and maintenance. Inhibition of KSP function leads to cell cycle arrest at mitosis with the formation of monoastral microtubule arrays, and ultimately, to cell death. Several KSP inhibitors are currently being studied in clinical trials and provide new opportunities for the development of novel anticancer therapeutics. RNA interference (RNAi) may represent a powerful strategy to interfere with key molecular pathways involved in cancer. In this study, we have established an efficient method for intratumoral delivery of siRNA. We evaluated short interfering RNA (siRNA) duplexes targeting luciferase as surrogate marker or KSP sequence. To examine the potential feasibility of RNAi therapy, the siRNA was transfected into pre-established lesions by means of intratumor electro-transfer of RNA therapeutics (IERT). This technology allowed cell permeation of the nucleic acids and to efficiently knock down gene expression, albeit transiently. The KSP-specific siRNA drastically reduced outgrowth of subcutaneous melanoma and ovarian cancer lesions. Our results show that intratumoral electro-transfer of siRNA is feasible and KSP-specific siRNA may provide a novel strategy for therapeutic intervention. J. Cell. Physiol. 228: 58-64, 2013. © 2012 Wiley Periodicals, Inc.

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Object The purpose of this study was to investigate whether diffusion tensor imaging (DTI) of the corticospinal tract (CST) is a reliable surrogate for intraoperative macrostimulation through the deep brain stimulation (DBS) leads. The authors hypothesized that the distance on MRI from the DBS lead to the CST as determined by DTI would correlate with intraoperative motor thresholds from macrostimulations through the same DBS lead. Methods The authors retrospectively reviewed pre- and postoperative MRI studies and intraoperative macrostimulation recordings in 17 patients with Parkinson disease (PD) treated by DBS stimulation. Preoperative DTI tractography of the CST was coregistered with postoperative MRI studies showing the position of the DBS leads. The shortest distance and the angle from each contact of each DBS lead to the CST was automatically calculated using software-based analysis. The distance measurements calculated for each contact were evaluated with respect to the intraoperative voltage thresholds that elicited a motor response at each contact. Results There was a nonsignificant trend for voltage thresholds to increase when the distances between the DBS leads and the CST increased. There was a significant correlation between the angle and the voltage, but the correlation was weak (coefficient of correlation [R] = 0.36). Conclusions Caution needs to be exercised when using DTI tractography information to guide DBS lead placement in patients with PD. Further studies are needed to compare DTI tractography measurements with other approaches such as microelectrode recordings and conventional intraoperative MRI-guided placement of DBS leads.

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The transmembrane protein HER2 is over-expressed in approximately 15% of invasive breast cancers as a result of HER2 gene amplification. HER2 proteolytic cleavage (HER2 shedding) generates soluble truncated HER2 molecules that include only the extracellular domain and the concentration of which can be measured in the serum fraction of blood. HER2 shedding also generates a constitutively active truncated intracellular receptor of 95kDa (p95(HER2)). Another soluble truncated HER2 protein (Herstatin), which can also be found in serum, is the product of an alternatively spliced HER2 transcript. Recent preclinical findings may provide crucial insights into the biological and clinical relevance of increased sHER2 concentrations for the outcome of HER2-positive breast cancer and sensitivity to trastuzumab and lapatinib treatment. We present here the most recent findings about the role and biology of sHER2 based on data obtained using a standardized test, which has been cleared by FDA in 2000, for measuring sHER2. This test includes quality control assessments and has been already widely used to evaluate the clinical utility of sHER2 as a biomarker in breast cancer. We will describe in detail data concerning the assessment of sHER2 as a surrogate maker to optimize the evaluation of the HER2 status of a primary tumor and as a prognosis and predictive marker of response to therapies, both in early and metastatic breast cancer.

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Adiponectin, which plays a pivotal role in metabolic liver diseases, is reduced in concentration in patients with NASH (non-alcoholic steatohepatitis). The aim of the present study was to determine adiponectin concentrations in patients with different forms and stages of chronic liver diseases. Serum adiponectin concentrations were measured in 232 fasting patients with chronic liver disease: 64 with NAFLD (non-alcoholic fatty liver disease), 123 with other chronic liver disease (e.g. viral hepatitis, n=71; autoimmune disease, n=18; alcohol-induced liver disease, n=3; or elevated liver enzymes of unknown origin, n=31) and 45 with cirrhosis. Circulating adiponectin levels were significantly lower in patients with NAFLD in comparison with patients with other chronic liver disease (4.8+/-3.5 compared with 10.4+/-6.3 microg/ml respectively; P<0.0001). Circulating adiponectin levels were significantly higher in patients with cirrhosis in comparison with patients without cirrhosis (18.6+/-14.5 compared with 8.4+/-6.1 microg/ml respectively; P<0.0001). Adiponectin concentrations correlated negatively with body weight (P<0.001), serum triacylglycerols (triglycerides) (P<0.001) and, in women, with BMI (body mass index) (P<0.001). Adiponectin concentrations correlated positively with serum bile acids (P<0.001), serum hyaluronic acid (P<0.001) and elastography values (P<0.001). Adiponectin levels were decreased in patients with NAFLD. In conclusion, adiponectin levels correlate positively with surrogate markers of hepatic fibrosis (transient elastography, fasting serum bile acids and hyaluronate) and are significantly elevated in cases of cirrhosis.

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Within pre-enlargement Europe, Italy records one of the widest employment rate gaps between highly and poorly educated women, as well one of the largest differences in the share, among working women, of public sector employment. Building on these stylized facts and using the Longitudinal Survey of Italian Households (ILFI), we investigate the working trajectories of three cohorts of Italian women born between 1935 and 1964 and observed from their first job until they are in their forties. We use mainly, but not exclusively, event history analysis in order to identify the main factors that influence entry into and exit from paid work over the life course. Our results suggest that in the Italian context, where employment protection policies have also been used as surrogate measures to favour reconciliation between family and work, and where traditional gender norms still persist, education is so important for women's employment decisions because it represents an investment in 'reconciliation' and 'work legitimacy' over and above investment in human capital.

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Osteoporosis is a serious worldwide epidemic. FRAX® is a web-based tool developed by the Sheffield WHO Collaborating Center team, that integrates clinical risk factors and femoral neck BMD and calculates the 10 year fracture probability in order to help health care professionals identify patients who need treatment. However, only 31 countries have a FRAX® calculator. In the absence of a FRAX® model for a particular country, it has been suggested to use a surrogate country for which the epidemiology of osteoporosis most closely approximates the index country. More specific recommendations for clinicians in these countries are not available. In North America, concerns have also been raised regarding the assumptions used to construct the US ethnic specific FRAX® calculators with respect to the correction factors applied to derive fracture probabilities in Blacks, Asians and Hispanics in comparison to Whites. In addition, questions were raised about calculating fracture risk in other ethnic groups e.g., Native Americans and First Canadians. The International Society for Clinical Densitometry (ISCD) in conjunction with the International Osteoporosis Foundation (IOF) assembled an international panel of experts that ultimately developed joint Official Positions of the ISCD and IOF advising clinicians regarding FRAX® usage. As part of the process, the charge of the FRAX® International Task Force was to review and synthesize data regarding geographic and race/ethnic variability in hip fractures, non-hip osteoporotic fractures, and make recommendations about the use of FRAX® in ethnic groups and countries without a FRAX® calculator. This synthesis was presented to the expert panel and constitutes the data on which the subsequent Official Positions are predicated. A summary of the International Task Force composition and charge is presented here.

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Aquest treball pretén analitzar l’ús dels procediments heurístics i els seus biaixos. Per això, hemrealitzat un estudi entre dues poblacions: 4rt d’Humanitats i 4rt d’ECO/ADE. Per dur a termeaquesta comparació hem realitzat una enquesta que pretenia detectar els biaixos. Amb elsresultats hem pogut comprovar que efectivament hi ha diferències significatives entre els dosgrups. Concretament, els estudiants d’ECO/ADE cometen menys biaixos.

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AIMS: Common carotid artery intima-media thickness (CCIMT) is widely used as a surrogate marker of atherosclerosis, given its predictive association with cardiovascular disease (CVD). The interpretation of CCIMT values has been hampered by the absence of reference values, however. We therefore aimed to establish reference intervals of CCIMT, obtained using the probably most accurate method at present (i.e. echotracking), to help interpretation of these measures. METHODS AND RESULTS: We combined CCIMT data obtained by echotracking on 24 871 individuals (53% men; age range 15-101 years) from 24 research centres worldwide. Individuals without CVD, cardiovascular risk factors (CV-RFs), and BP-, lipid-, and/or glucose-lowering medication constituted a healthy sub-population (n = 4234) used to establish sex-specific equations for percentiles of CCIMT across age. With these equations, we generated CCIMT Z-scores in different reference sub-populations, thereby allowing for a standardized comparison between observed and predicted ('normal') values from individuals of the same age and sex. In the sub-population without CVD and treatment (n = 14 609), and in men and women, respectively, CCIMT Z-scores were independently associated with systolic blood pressure [standardized βs 0.19 (95% CI: 0.16-0.22) and 0.18 (0.15-0.21)], smoking [0.25 (0.19-0.31) and 0.11 (0.04-0.18)], diabetes [0.19 (0.05-0.33) and 0.19 (0.02-0.36)], total-to-HDL cholesterol ratio [0.07 (0.04-0.10) and 0.05 (0.02-0.09)], and body mass index [0.14 (0.12-0.17) and 0.07 (0.04-0.10)]. CONCLUSION: We estimated age- and sex-specific percentiles of CCIMT in a healthy population and assessed the association of CV-RFs with CCIMT Z-scores, which enables comparison of IMT values for (patient) groups with different cardiovascular risk profiles, helping interpretation of such measures obtained both in research and clinical settings.

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BACKGROUND: No data on long-term outcomes of survivors of 2009 influenza A(H1N1) (A[H1N1])-associated ARDS are available. The objective of this study was to compare the 1-year outcomes of survivors of A(H1N1)-associated ARDS, according to use or no use of extracorporeal lung assist (ECLA), using its need as an ARDS severity surrogate. METHODS: Survivors of ARDS (12 with ECLA use vs 25 without, corresponding to 75% and 54% of the eligible patients for each group, respectively) selected from the Réseau Européen de Ventilation Artificielle (REVA) registry had previously been healthy, with only pregnancy and/or moderate obesity (BMI ≤ 35 kg/m²) as known risk factors for A(H1N1) infection. Lung function and morphology, health-related quality of life (HRQoL), and psychologic impairment were evaluated. RESULTS: At 1 year post-ICU discharge for the ECLA and no-ECLA groups, respectively, 50% and 40% reported significant exertion dyspnea, 83% and 64% had returned to work, and 75% and 64% had decreased diffusion capacity across the blood-gas barrier, despite their near-normal and similar lung function test results. For both groups, exercise test results showed diminished but comparable exercise capacities, with similar alveolar-arterial oxygen gradients at peak exercise, and CT scans showed minor abnormal findings. HRQoL assessed by the 36-Item Short-Form Health Survey was poorer for both groups than for a sex- and age-matched general population group, but without between-group differences. ECLA and no-ECLA group patients, respectively, had symptoms of anxiety (50% and 56%) and depression (28% and 28%) and were at risk for posttraumatic stress disorder (41% and 44%). CONCLUSIONS: One year post-ICU discharge, a majority of survivors of A(H1N1)-associated ARDS had minor lung disabilities with diminished diffusion capacities across the blood-gas barrier, and most had psychologic impairment and poorer HRQoL than a sex- and age-matched general population group. ECLA and no-ECLA group patients had comparable outcomes. TRIAL REGISTRY: ClinicalTrials.gov; No.: NCT01271842; URL: www.clinicaltrials.gov

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OBJECTIVES: The aim of this study was to evaluate right ventricular (RV) and left ventricular function and pulmonary circulation in chronic mountain sickness (CMS) patients with rest and stress echocardiography compared with healthy high-altitude (HA) dwellers. BACKGROUND: CMS or Monge's disease is defined by excessive erythrocytosis (hemoglobin >21 g/dl in males, 19 g/dl in females) and severe hypoxemia. In some cases, a moderate or severe increase in pulmonary pressure is present, suggesting a similar pathogenesis of pulmonary hypertension. METHODS: In La Paz (Bolivia, 3,600 m sea level), 46 CMS patients and 40 HA dwellers of similar age were evaluated at rest and during semisupine bicycle exercise. Pulmonary artery pressure (PAP), pulmonary vascular resistance, and cardiac function were estimated by Doppler echocardiography. RESULTS: Compared with HA dwellers, CMS patients showed RV dilation at rest (RV mid diameter: 36 ± 5 mm vs. 32 ± 4 mm, CMS vs. HA, p = 0.001) and reduced RV fractional area change both at rest (35 ± 9% vs. 43 ± 9%, p = 0.002) and during exercise (36 ± 9% vs. 43 ± 8%, CMS vs. HA, p = 0.005). The RV systolic longitudinal function (RV-S') decreased in CMS patients, whereas it increased in the control patients (p < 0.0001) at peak stress. The RV end-systolic pressure-area relationship, a load independent surrogate of RV contractility, was similar in CMS patients and HA dwellers with a significant increase in systolic PAP and pulmonary vascular resistance in CMS patients (systolic PAP: 50 ± 12 mm Hg vs. 38 ± 8 mm Hg, CMS vs. HA, p < 0.0001; pulmonary vascular resistance: 2.9 ± 1 mm Hg/min/l vs. 2.2 ± 1 mm Hg/min/l, p = 0.03). Both groups showed comparable systolic and diastolic left ventricular function both at rest and during stress. CONCLUSIONS: Comparable RV contractile reserve in CMS and HA suggests that the lower resting values of RV function in CMS may represent a physiological adaptation to chronic hypoxic conditions rather than impaired RV function. (Chronic Mountain Sickness, Systemic Vascular Function [CMS]; NCT01182792).

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The Convention on Biological Diversity (CBD) aims at the conservation of all three levels of biodiversity, that is, ecosystems, species and genes. Genetic diversity represents evolutionary potential and is important for ecosystem functioning. Unfortunately, genetic diversity in natural populations is hardly considered in conservation strategies because it is difficult to measure and has been hypothesised to co-vary with species richness. This means that species richness is taken as a surrogate of genetic diversity in conservation planning, though their relationship has not been properly evaluated. We tested whether the genetic and species levels of biodiversity co-vary, using a large-scale and multi-species approach. We chose the high-mountain flora of the Alps and the Carpathians as study systems and demonstrate that species richness and genetic diversity are not correlated. Species richness thus cannot act as a surrogate for genetic diversity. Our results have important consequences for implementing the CBD when designing conservation strategies.

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PURPOSE: This study was performed to determine the impact of perfusion and diffusion magnetic resonance imaging (MRI) sequences on patients during treatment of newly diagnosed glioblastoma. Special emphasis has been given to these imaging technologies as tools to potentially anticipate disease progression, as progression-free survival is frequently used as a surrogate endpoint. METHODS AND MATERIALS: Forty-one patients from a phase II temolozomide clinical trial were included. During follow-up, images were integrated 21 to 28 days after radiochemotherapy and every 2 months thereafter. Assessment of scans included measurement of size of lesion on T1 contrast-enhanced, T2, diffusion, and perfusion images, as well as mass effect. Classical criteria on tumor size variation and clinical parameters were used to set disease progression date. RESULTS: A total of 311 MRI examinations were reviewed. At disease progression (32 patients), a multivariate Cox regression determined 2 significant survival parameters: T1 largest diameter (p < 0.02) and T2 size variation (p < 0.05), whereas perfusion and diffusion were not significant. CONCLUSION: Perfusion and diffusion techniques cannot be used to anticipate tumor progression. Decision making at disease progression is critical, and classical T1 and T2 imaging remain the gold standard. Specifically, a T1 contrast enhancement over 3 cm in largest diameter together with an increased T2 hypersignal is a marker of inferior prognosis.

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La metáfora y el símbolo constituyen eje central de esta investigación, la cual en principio no pretende ser un estudio exhaustivo de estos conceptos, tarea que requeriría muchos años de indagación y búsqueda, al ser éste un primer acercamiento a un controvertido, sugerente e interesante problema que se encuentra no sólo en las raíces de nuestro lenguaje, sino también de nuestro pensamiento y por tanto del devenir filosófico. El recurso de la metáfora y el símbolo, no sólo es propio de la literatura sino común a toda obra humana. Tal es el caso de los mitos, las alegorías, la poesía, las obras de teatro, los ensayos —que a menudo los contienen— y los modelos a escalas tanto teóricos como reales con los que trabaja la ciencia para luego, transferir lo peculiar de la ficción heurística a la realidad.

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In the last 50 years, concern about the loss of lichen diversity associated with forest management and forest fragmentation has led to many studies designed to assess patterns and monitor trends of lichen biodiversity in forests worldwide. However there are surprisingly few studies focusing on the effect of natural disturbance for epiphytic lichens in forest ecosystems and, especially, on how these changes affect the relationships between epiphytic lichens and other organisms. The major goal of this thesis was to characterize and valuate the epiphytic lichens in the Baixo Tamega region (northern Portugal) and to assess its vulnerability to several drivers of change, particularly fire. The study area is located in Aboboreira and Castelo, a mountain area with 105 km2 and a top altitude of approximately 1000 m.a.s.l. In this region, fire is one of the worst natural catastrophes not only because of its high frequency and wide extension but also because of their enormous destructive effects. This thesis has included three case studies that proved the need to develop management and conservation actions for the area. In the first study we assessed the epiphytic lichen diversity in the oak woods of the Aboboreira and Castelo mountains. Results have revealed high diversity value and presence of a lichen community that has suffered general decline throughout Europe. The second study has addressed the impact of fire over epiphytic lichens and community recovering patterns. Results observed along the fire gradient showed that the most common and abundant lichen species establish themselves early in post-fire gradient while “old-growth” associated lichens tend to recover slowly along the same gradient. The third study intended to evaluate the potential use of selected lichen species or groups as biodiversity surrogates, in a scenario of fire-controlled ecological changes. Results showed that the use of epiphytic lichens as surrogates of bryophyte and vascular plant diversity should consider not only species richeness and composition, but also occurrence of disturbing factors, such fire. among the studied groups, lichen genera is the only group that can be used as surrogate of total epiphytic lichen diversity, independently of fire induced changes

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Despite the speciose fauna of gall-inducing insects in the Neotropical region, little is known about their taxonomy. On the other hand, gall morphotypes associated with host species have been extensively used as a surrogate of the inducer species worldwide. This study reviewed the described gall midges and their galls to test the generalization on the use of gall morphotypes as surrogates of gall midge species in the Brazilian fauna. We compiled taxonomic and biological data for 196 gall midge species recorded on 128 host plant species. Ninety two percent of those species were monophagous, inducing galls on a single host plant species, whereas only 5.6% species were oligophagous, inducing galls on more than one congeneric host plant species. Only four species induced galls on more than one host plant genus. We conclude that gall morphotypes associated with information on the host plant species and attacked organs are reliable surrogates of the gall-inducing species.