882 resultados para further steps
Resumo:
The well-known lack of power of unit root tests has often been attributed to the shortlength of macroeconomic variables and also to DGP s that depart from the I(1)-I(0)alternatives. This paper shows that by using long spans of annual real GNP and GNPper capita (133 years) high power can be achieved, leading to the rejection of both theunit root and the trend-stationary hypothesis. This suggests that possibly neither modelprovides a good characterization of these data. Next, more flexible representations areconsidered, namely, processes containing structural breaks (SB) and fractional ordersof integration (FI). Economic justification for the presence of these features in GNP isprovided. It is shown that the latter models (FI and SB) are in general preferred to theARIMA (I(1) or I(0)) ones. As a novelty in this literature, new techniques are appliedto discriminate between FI and SB models. It turns out that the FI specification ispreferred, implying that GNP and GNP per capita are non-stationary, highly persistentbut mean-reverting series. Finally, it is shown that the results are robust when breaksin the deterministic component are allowed for in the FI model. Some macroeconomicimplications of these findings are also discussed.
Resumo:
During free walking, gait is automatically adjusted to provide optimal mechanical output and minimal energy expenditure; gait parameters, such as cadence, fluctuate from one stride to the next around average values. It was described that this fluctuation exhibited long-range correlations and fractal-like patterns. In addition, it was suggested that these long-range correlations disappeared if the participant followed the beep of metronome to regulate his or her pace. Until now, these fractal fluctuations were only observed for stride interval, because no technique existed to adequately analyze an extended time of free walking. The aim of the present study was to measure walking speed (WS), step frequency (SF) and step length (SL) with high accuracy (<1 cm) satellite positioning method (global positioning system or GPS) in order to detect long-range correlations in the stride-to-stride fluctuations. Eight participants walked 30 min under free and constrained (metronome) conditions. Under free walking conditions, DFA (detrended fluctuation analysis) and surrogate data tests showed that the fluctuation of WS, SL and SF exhibited a fractal pattern (i.e., scaling exponent alpha: 0.5 < alpha < 1) in a large majority of participants (7/8). Under constrained conditions (metronome), SF fluctuations became significantly anti-correlated (alpha < 0.5) in all participants. However, the scaling exponent of SL and WS was not modified. We conclude that, when the walking pace is controlled by an auditory signal, the feedback loop between the planned movement (at supraspinal level) and the sensory inputs induces a continual shifting of SF around the mean (persistent anti-correlation), but with no effect on the fluctuation dynamics of the other parameters (SL, WS).
Resumo:
Τ cell activation via the Τ cell receptor (TCR) through antigen recognition is one of the key steps to initiate the adaptive immune response. The mechanisms controlling TCR-induced signaling pathways are the subject of intense research, since deregulated signaling in lymphocytes can lead to immunodeficiency, autoimmunity or lymphomas. In Τ lymphocytes a complex composed of CARMA1, BCL10 and MALT1 has been identified to receive signals from TCR proximal events and to induce further signals crucial for Τ cell activation. MALT1 is scaffold protein and a cysteine protease and both functions have been shown, among other effects, to be crucial to initiate the activation of the transcription factors of the nuclear factor κΒ (NF-κΒ) family after TCR-stimulation. Several proteolytic targets have been described recently and all of them play roles in modulating NF-κΒ activation or other aspects of Τ cell activation. In this study, we describe a novel target of MALT1, Caspase-10. Two isoforms of Caspase-10 are cleaved by MALTI in Τ and Β cells after antigen receptor stimulation. Caspases are a family of cysteine proteases that are known for their roles in cell death and certain immune functions. Caspase-10 has so far only been reported to be involved in the induction of apoptosis. However it is very closely related to the well-characterized Caspase-8 that has been reported to be involved in Τ cell activation. In the present study, we describe a crucial role for Caspase-10, but not Caspase-8, in Τ cell activation after TCR stimulation. Jurkat Τ cells silenced for Caspase-10 expression exhibit a dramatic reduction in IL-2 production following stimulation. The data obtained revealed that this is due to severely reduced activation of activator protein-1 (AP-1), another transcription factor family with key functions in the process of Τ cell activation. We observed strongly reduced expression levels of the AP-1 family member c-Fos after Τ cell stimulation. This transcription factor is expressed upon TCR stimulation and is a crucial component of AP-1 transcription factor dimers required for Τ cell activation. In further analysis, it was shown that this defect is not based on reduced transcription, as the c-Fos mRNA levels are not altered, but rather seems to be caused by a defect in translation or protein stability in the absence of Caspase-10. Furthermore, we report a potential interaction of the c-Fos protein and Caspsae-10. This role of Caspase-10 in AP-1 activation however is independent of its cleavage by MALT1, leaving the role of Caspase-10 cleavage in activated lymphocytes unclear. Taken together, these results give new insights into the complex matter of lymphocyte activation whose understanding is crucial for the development of new drugs modulating the immune response or inhibiting lymphoma progression.
Resumo:
Challenging environmental conditions, including heat and humidity, cold, and altitude, pose particular risks to the health of Olympic and other high-level athletes. As a further commitment to athlete safety, the International Olympic Committee (IOC) Medical Commission convened a panel of experts to review the scientific evidence base, reach consensus, and underscore practical safety guidelines and new research priorities regarding the unique environmental challenges Olympic and other international-level athletes face. For non-aquatic events, external thermal load is dependent on ambient temperature, humidity, wind speed and solar radiation, while clothing and protective gear can measurably increase thermal strain and prompt premature fatigue. In swimmers, body heat loss is the direct result of convection at a rate that is proportional to the effective water velocity around the swimmer and the temperature difference between the skin and the water. Other cold exposure and conditions, such as during Alpine skiing, biathlon and other sliding sports, facilitate body heat transfer to the environment, potentially leading to hypothermia and/or frostbite; although metabolic heat production during these activities usually increases well above the rate of body heat loss, and protective clothing and limited exposure time in certain events reduces these clinical risks as well. Most athletic events are held at altitudes that pose little to no health risks; and training exposures are typically brief and well-tolerated. While these and other environment-related threats to performance and safety can be lessened or averted by implementing a variety of individual and event preventative measures, more research and evidence-based guidelines and recommendations are needed. In the mean time, the IOC Medical Commission and International Sport Federations have implemented new guidelines and taken additional steps to mitigate risk even further.
Resumo:
PURPOSE OF REVIEW: Many chemotherapeutic drugs, including fluoropyrimidines, platinums, CPT-11, taxanes and adriamycin have single-agent activity in advanced gastric cancer. Although combination chemotherapy has been shown to be more effective than single agents, response rates between 30 and 50% have not fulfilled their promise as progression-free survival from the best combinations ranges between 3 and 7 months and overall survival between 8 and 11 months. The development of targeted therapies in gastric cancer clearly stays behind the integration of these novel agents into new treatment concepts for patients with colorectal cancer. This review summarizes the experience and major recent advances in the development of targeted therapies in advanced gastric cancer. RECENT FINDINGS: Recent publications on targeted therapies in gastric cancer are limited to nonrandomized phase I or II trials. The majority of agents tested were angiogenesis inhibitors or agents targeting the epidermal growth factor receptors epidermal growth factor receptor 1 and HER2. SUMMARY: Adequately powered, randomized phase III trials are necessary to define the clinical role of targeted therapies in advanced gastric cancer. Biomarker studies to correlate with treatment outcomes will be critical to identify patients who benefit most from chemotherapy and targeted therapy.
Resumo:
Psychological control refers to parental behaviors that intrude on the psychological and emotional development of the child. In 2010, Soenens and colleagues proposed a distinction between two domain-specific expressions of psychological control, that is, Dependency-oriented Psychological Control (DPC) and Achievement-oriented Psychological Control (APC). The aim of this study was to evaluate the factor structure, reliability, and convergent validity of the French form of the Dependency-oriented and Achievement-oriented Psychological Control Scale (DAPCS; Soenens, Vansteenkiste, and Luyten, 2010) in a sample of late adolescents (N = 291, mean age = 21.65). Confirmatory factor analyses confirmed the hypothesized two-factor solution of the DAPCS for paternal as well as for maternal ratings. Moreover, high indices of internal consistency indicated that both subscales produced reliable scores. Further, convergent validity was confirmed by theoretically consistent associations between the DAPCS' subscales and well-established assessments of general parenting style dimensions. Finally, results evidenced gender specific patterns supporting the relevance of domain differentiation in the assessment of psychological control. Overall, the results of this study indicated that the French form of the DAPCS might be a useful instrument to assess two domainspecific types of parental psychological control among French-speaking adolescents.
Resumo:
This paper reports the results from a second characterisation of the 91500 zircon, including data from electron probe microanalysis, laser ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS), secondary ion mass spectrometry (SIMS) and laser fluorination analyses. The focus of this initiative was to establish the suitability of this large single zircon crystal for calibrating in situ analyses of the rare earth elements and oxygen isotopes, as well as to provide working values for key geochemical systems. In addition to extensive testing of the chemical and structural homogeneity of this sample, the occurrence of banding in 91500 in both backscattered electron and cathodoluminescence images is described in detail. Blind intercomparison data reported by both LA-ICP-MS and SIMS laboratories indicate that only small systematic differences exist between the data sets provided by these two techniques. Furthermore, the use of NIST SRM 610 glass as the calibrant for SIMS analyses was found to introduce little or no systematic error into the results for zircon. Based on both laser fluorination and SIMS data, zircon 91500 seems to be very well suited for calibrating in situ oxygen isotopic analyses.
Resumo:
Purpose:Lentiviral vectors are among the most efficient gene transfer tools for both dividing and non dividing cells, including pigmented epithelial cells of the retina. One of the latest developments in the field, which represents a significant advance in biosafety, consists in the use of non integrative lentiviral vectors (NILVs). These newly described tools were already shown to be efficient in various tissues, such as the retina. They allow prolonged transgene expression as long as the transduced cells do not divide or divide slowly. However, they were also shown to induce transgene expression less efficiently than their integrative counterparts. Further investigations are thus needed to improve their potential. To this aim, different strategies are under evaluation. In this study, we focused on using different integrase mutations. Methods:We considered different integrase mutations, including modifications in the catalytic site and in the C-terminal domain of the enzyme. Lentiviral vectors bearing these mutant integrases and allowing expression of various transgenes were produced and characterized in vitro and in vivo. In particular, we evaluated their transgene expression capability. Influence of integrase mutation on the residual integration activity was also investigated. Results:In line with the fact that the lentiviral integrase is involved in several steps of the replication cycle of lentiviruses, we observed that integrase mutations can modify lentiviral vector features, resulting in different transduction efficiencies as well as modulation of the integration activity. Conclusions:NILVs appear as suitable tools for gene transfer in the retina, particularly to transduce RPE cells. They can be advantageously used, for instance, to develop neuroprotective strategies aimed at rescuing photoreceptors from death in various retinal diseases.
Resumo:
Natural Killer (NK) cells are innate immune cells that can eliminate malignant and foreign cells and that play an important role for the early control of viral and fungal infections. Further, they are important regulators of the adaptive and innate immune responses. During their development in the bone marrow (BM) NK cells undergo several maturation steps that directly establish an effector program. The transcriptional network that controls NK cell development and maturation is still incompletely understood. Based on earlier findings that NK cell numbers are reduced in the absence of the transcription factor T cell factor-1 (Tcf-1), my thesis has addressed the precise role of this transcription factor for NK cell development, maturation and function and whether Tcf-1 acts as a nuclear effector of the canonical Wnt signaling pathway to mediate its effects. It is shown that Tcf-1 is selectively required for the emergence of mature BM NK cells. Surprisingly, the emergence of BM NK cells depends on the repressor function of Tcf-1 and is independent of the Wnt pathway. In BM and peripheral NK cells Tcf-1 is found to suppress Granzyme B (GzmB) expression, a key cytotoxic effector molecule required to kill target cells. We provide evidence that GzmB over-expression in the absence of Tcf-1 results in accelerated spontaneous death of bone marrow NK cells and of cytokine stimulated peripheral NK cells. Moreover, Tcf-1 deficient NK cells show reduced target cell killing, which is due to enhanced GzmB-dependent NK cell death induced by the recognition of tumour target cells. Collectively, these data provide significant new insights into the transcriptional regulation of NK cell development and function and suggest a novel mechanism that protects NK cells from the deleterious effects of highly cytotoxic effector molecules. - Les cellules NK (de l'anglais Natural Killer) font partie du système immunitaire inné et sont capables d'éliminer à elles seules les cellules cancéreuses ou infectées. Ces cellules participent dans la régulation et la coordination des réponses innée et adaptative. Lors de leur développement dans la moelle osseuse, les cellules NK vont acquérir leurs fonctions effectrices, un processus contrôlé par des facteurs de transcription mais encore peu connu. Des précédentes travaux ont montré qu'une diminution du nombre de cellules NK corrélait avec l'absence du facteur de transcription Tcf-1 (T cell factor-1), suggérant un rôle important de Tcf-1 dans le développement de cellules NK. Cette thèse a pour but de mieux comprendre le rôle du facteur de transcription Tcf-1 lors du développement et la maturation des cellules NK, ainsi que son interaction avec la voie de signalisation Wnt. Nous avons montré que Tcf-1 est essentiel pour la transition des cellules immatures NK (iNK) à des cellules matures NK (mNK) dans la moelle osseuse, et cela de manière indépendamment de la voie de signalisation Wnt. De manière intéressante, nous avons observé qu'en absence du facteur de transcription Tcf-1, les cellules NK augmentaient l'expression de la protéine Granzyme B (GzmB), une protéine essentielle pour l'élimination des cellules cancéreuses ou infectées. Ceci a pour conséquence, une augmentation de la mort des cellules mNK dans la moelle osseuse ainsi qu'une diminution de leur fonction «tueuses». Ces résultats montrent pour la première fois, le rôle répresseur du facteur de transcription Tcf-1 dans l'expression de la protéine GzmB. L'ensemble de ces résultats apporte de nouveaux éléments concernant le rôle de Tcf-1 dans la régulation du développement et de la fonction des cellules NK et suggèrent un nouveau mécanisme cellulaire de protection contre les effets délétères d'une dérégulation de l'expression des molécules cytotoxique.
Resumo:
The flourishing number of publications on the use of isotope ratio mass spectrometry (IRMS) in forensic science denotes the enthusiasm and the attraction generated by this technology. IRMS has demonstrated its potential to distinguish chemically identical compounds coming from different sources. Despite the numerous applications of IRMS to a wide range of forensic materials, its implementation in a forensic framework is less straightforward than it appears. In addition, each laboratory has developed its own strategy of analysis on calibration, sequence design, standards utilisation and data treatment without a clear consensus.Through the experience acquired from research undertaken in different forensic fields, we propose a methodological framework of the whole process using IRMS methods. We emphasize the importance of considering isotopic results as part of a whole approach, when applying this technology to a particular forensic issue. The process is divided into six different steps, which should be considered for a thoughtful and relevant application. The dissection of this process into fundamental steps, further detailed, enables a better understanding of the essential, though not exhaustive, factors that have to be considered in order to obtain results of quality and sufficiently robust to proceed to retrospective analyses or interlaboratory comparisons.
Resumo:
The combination of oxaliplatin, leucovorin and 5-fluorouracil (FOLFOX-4) is still a reference regimen in advanced colorectal cancer; however, the addition of new biologic compounds represents a significant way forward. Bortezomib is an inhibitor of proteasome, a multicatalytic enzyme complex that degrades several intracellular proteins. In this study, escalating doses of Bortezomib were administered along with the standard FOLFOX-4 doses, in order to evaluate the dose-limiting toxicity (DLT), toxicity profile and activity of the combination. Patients with advanced colorectal cancer, unpretreated for metastatic disease, were enroled in the study. Bortezomib starting dose was 1.3mg/m(2), which was to be escalated in the subsequent steps according to the toxicities observed after first cycle. Exploratory pharmacogenetics research was conducted by analysing the association between clinical outcomes and polymorphisms in candidate genes for response to each of the used drugs. Correlation between tumour marker changes and response was also investigated. One mg/m(2) (DL-1) was defined as being the maximum tolerated dose since only 1 DLT was observed in 6 patients. The main toxicities were haematologic, neuropathy, diarrhoea and fatigue. Amongst 13 evaluable patients, five had a partial response, five had a stable disease and three patients progressed. Two patients are long-term survivors after a combined chemosurgical approach. Further trials of the current combination may be justified.
Resumo:
The mechanisms of blood vessel maturation into distinct parts of the blood vasculature such as arteries, veins, and capillaries have been the subject of intense investigation over recent years. In contrast, our knowledge of lymphatic vessel maturation is still fragmentary. In this study, we provide a molecular and morphological characterization of the major steps in the maturation of the primary lymphatic capillary plexus into collecting lymphatic vessels during development and show that forkhead transcription factor Foxc2 controls this process. We further identify transcription factor NFATc1 as a novel regulator of lymphatic development and describe a previously unsuspected link between NFATc1 and Foxc2 in the regulation of lymphatic maturation. We also provide a genome-wide map of FOXC2-binding sites in lymphatic endothelial cells, identify a novel consensus FOXC2 sequence, and show that NFATc1 physically interacts with FOXC2-binding enhancers. These data provide novel insights into the molecular program of lymphatic vascular specification and suggest that FOXC2 and NFATc1 are potential targets for therapeutic intervention.