989 resultados para Regulation-loop frequency


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Leishmania infected of Lutzomyia spp. are rare in endemic areas. We tested the hypothesis that there is clustering of infected vectors by combining pinpoint capture with sensitive L. braziliensis kDNA minicircle specific PCR/dot blot in an endemic area in the State of Bahia. Thirty out of 335 samples (10 to 20 sand flies/sample; total of 4,027 female sand flies) were positive by PCR analysis and dot blot leading to a underestimated overall rate of 0.4% positive phlebotomines. However, 83.3% of the positive samples were contributed by a single sector out of four sectors of the whole studied area. This resulted in a rate of 1.5% Leishmania positive phlebotomines for this sector, far above rates of other sectors. Incidence of American cutaneous leishmaniasis cases for this sector was about twice that for other sectors. Our results show that there is a non-homogeneous distribution of Leishmania-infected vectors. Such a clustering may have implications in control strategies against leishmaniasis, and reinforces the necessity of understanding the ecological and geographical factors involved in leishmanial transmission.

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Oscillations have been increasingly recognized as a core property of neural responses that contribute to spontaneous, induced, and evoked activities within and between individual neurons and neural ensembles. They are considered as a prominent mechanism for information processing within and communication between brain areas. More recently, it has been proposed that interactions between periodic components at different frequencies, known as cross-frequency couplings, may support the integration of neuronal oscillations at different temporal and spatial scales. The present study details methods based on an adaptive frequency tracking approach that improve the quantification and statistical analysis of oscillatory components and cross-frequency couplings. This approach allows for time-varying instantaneous frequency, which is particularly important when measuring phase interactions between components. We compared this adaptive approach to traditional band-pass filters in their measurement of phase-amplitude and phase-phase cross-frequency couplings. Evaluations were performed with synthetic signals and EEG data recorded from healthy humans performing an illusory contour discrimination task. First, the synthetic signals in conjunction with Monte Carlo simulations highlighted two desirable features of the proposed algorithm vs. classical filter-bank approaches: resilience to broad-band noise and oscillatory interference. Second, the analyses with real EEG signals revealed statistically more robust effects (i.e. improved sensitivity) when using an adaptive frequency tracking framework, particularly when identifying phase-amplitude couplings. This was further confirmed after generating surrogate signals from the real EEG data. Adaptive frequency tracking appears to improve the measurements of cross-frequency couplings through precise extraction of neuronal oscillations.

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This report has been written in the context of this interest and in response to a request from the Department of Health and Children. It follows a Forum on regulatory issues that was held at the IPA in June 2001 and attended by many CAM practitioners. The Minister for Health and Children asked the Institute to build on the discussions at the Forum by preparing a report on possible options in the regulation of CAM practitioners in Ireland. The focus of the report is on regulatory and policy issues in general. It is not within the Instituteâ?Ts competence or brief to comment on more specific clinical or technical issues. Download the document here

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The mechanisms through which aldosterone promotes apparently opposite effects like salt reabsorption and K(+) secretion remain poorly understood. The identification, localization, and physiological analysis of ion transport systems in distal nephron have revealed an intricate network of interactions between several players, revealing the complex mechanism behind the aldosterone paradox. We review the mechanisms involved in differential regulation of ion transport that allow the fine tuning of salt and K(+) balance.

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Given the urgence of a new paradigm in wireless digital trasmission which should allow for higher bit rate, lower latency and tigher delay constaints, it has been proposed to investigate the fundamental building blocks that at the circuital/device level, will boost the change towards a more efficient network architecture, with high capacity, higher bandwidth and a more satisfactory end user experience. At the core of each transciever, there are inherently analog devices capable of providing the carrier signal, the oscillators. It is strongly believed that many limitations in today's communication protocols, could be relieved by permitting high carrier frequency radio transmission, and having some degree of reconfigurability. This led us to studying distributed oscillator architectures which work in the microwave range and possess wideband tuning capability. As microvave oscillators are essentially nonlinear devices, a full nonlinear analyis, synthesis, and optimization had to be considered for their implementation. Consequently, all the most used nonlinear numerical techniques in commercial EDA software had been reviewed. An application of all the aforementioned techniques has been shown, considering a systems of three coupled oscillator ("triple push" oscillator) in which the stability of the various oscillating modes has been studied. Provided that a certain phase distribution is maintained among the oscillating elements, this topology permits a rise in the output power of the third harmonic; nevertheless due to circuit simmetry, "unwanted" oscillating modes coexist with the intenteded one. Starting with the necessary background on distributed amplification and distributed oscillator theory, the design of a four stage reverse mode distributed voltage controlled oscillator (DVCO) using lumped elments has been presented. All the design steps have been reported and for the first time a method for an optimized design with reduced variations in the output power has been presented. Ongoing work is devoted to model a wideband DVCO and to implement a frequency divider.

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OBJECTIVE: To investigate the involvement of the nuclear factor (NF)-kappaB in the interleukin (IL)-1 beta-mediated macrophage migration inhibitory factor (MIF) gene activation. DESIGN: Prospective study. SETTING: Human reproduction research laboratory. PATIENT(S): Nine women with endometriotic lesions. INTERVENTION(S): Endometriotic lesions were obtained during laparoscopic surgery. MAIN OUTCOME MEASURE(S): The MIF protein secretion was analyzed by ELISA, MIF mRNA expression by quantitative real-time polymerase chain reaction (PCR), NF-kappaB translocation into the nucleus by electrophoresis mobility shift assay, I kappaB phosphorylation and degradation by Western blot, and human MIF promoter activity by transient cell transfection. RESULT(S): This study showed a significant dose-dependent increase of MIF protein secretion and mRNA expression, the NF-kappaB translocation into the nucleus, I kappaB phosphorylation, I kappaB degradation, and human MIF promoter activity in endometriotic stromal cells in response to IL-1 beta. Curcumin (NF-kappaB inhibitor) significantly inhibited all these IL-1 beta-mediated effects. Analysis of the activity of deletion constructs of the human MIF promoter and a computer search localized two putative regulatory elements corresponding to NF-kappaB binding sites at positions -2538/-2528 bp and -1389/-1380 bp. CONCLUSION(S): This study suggests the involvement of the nuclear transcription factor NF-kappaB in MIF gene activation in ectopic endometrial cells in response to IL-1 beta and identifies a possible pathway of endometriosis-associated inflammation and ectopic cell growth.

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Biopsies from human localized cutaneous lesions (LCL n = 7) or disseminated lesions (DL n = 8) cases were characterized according to cellular infiltration,frequency of cytokine (IFN-g, TNF-alpha) or iNOS enzyme producing cells. LCL, the most usual form of the disease with usually one or two lesions, exhibits extensive tissue damage. DL is a rare form with widespread lesions throughout the body; exhibiting poor parasite containment but less tissue damage. We demonstrated that LCL lesions exhibit higher frequency of B lymphocytes and a higher intensity of IFN-gamma expression. In both forms of the disease CD8+ were found in higher frequency than CD4+ T cells. Frequency of TNF-alpha and iNOS producing cells, as well as the frequency of CD68+ macrophages, did not differ between LCL and DL. Our findings reinforce the link between an efficient control of parasite and tissue damage, implicating higher frequency of IFN-gamma producing cells, as well as its possible counteraction by infiltrated B cells and hence possible humoral immune response in situ.

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Gene expression signatures are used in the clinic as prognostic tools to determine the risk of individual patients with localized breast tumors developing distant metastasis. We lack a clear understanding, however, of whether these correlative biomarkers link to a common biological network that regulates metastasis. We find that the c-MYC oncoprotein coordinately regulates the expression of 13 different "poor-outcome" cancer signatures. In addition, functional inactivation of MYC in human breast cancer cells specifically inhibits distant metastasis in vivo and invasive behavior in vitro of these cells. These results suggest that MYC oncogene activity (as marked by "poor-prognosis" signature expression) may be necessary for the translocation of poor-outcome human breast tumors to distant sites.

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Some authors argue that both substance dependence and eating disorders should be considered as dependent behaviours. Similarities and differences between these disorders, however, remain unclear. This study compares processes of emotion regulation in adolescents and young adults (15 to 25 years old) with substance dependence (SD) or eating disorders (ED). One hundred and thirteen SD, 50 ED and 86 non-clinical subjects (NC), recruited in four French and Swiss locations, completed a self-report questionnaire of emotion regulation strategies. This questionnaire addresses the subjects' relationships, concerning past and present family, and refers to Main's (1990) concept of primary strategy (balanced activation and deactivation of attachment behaviours), and of secondary strategies (hyperactivation or excessive deactivation of the attachment system). Participants were also questioned in structured interviews, about life events and DSM-IV classification criteria. SD reported more adverse events than ED and NC. SD and ED reported using fewer primary strategies than NC, and SD had secondary strategies that were different from those of ED. Patients with eating disorders reported more hyperactivation, and SD reported more deactivation of the attachment system. It is hypothesized that while subjects with SD and ED have in common poorly regulated strategies, they differ in the way they process emotion or relationship-related information.

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We use store-specific data for a major UK supermarket chain to estimate the impact of planning on store output. Using the quasi-natural experiment of the variation in policies between England and other UK countries, we isolate the impact of Town Centre First policies. We find that space contributes directly to store productivity; and planning policies in England directly reduce output both by reducing store sizes and forcing stores onto less productive sites. We estimate that since the late 1980s planning policies have imposed a loss of output of at least 18.3 to 24.9% - more than a “lost decade’s” growth. JEL codes: D2, L51, L81, R32.

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OBJECTIVE: To compare the expression of the prostaglandin (PG) E(2) transporter multidrug resistance-associated protein 4 (MRP4) in eutopic and ectopic endometrial tissue from endometriosis patients with that of control subjects and to examine whether MRP4 is regulated by the antiinflammatory lipid lipoxin A(4) (LXA(4)) in endometriotic epithelial cells. DESIGN: Molecular analysis in human samples and a cell line. SETTING: Two university hospitals and a private clinic. PATIENT(S): A total of 59 endometriosis patients and 32 age- and body mass index-matched control subjects undergoing laparoscopy or hysterectomy. INTERVENTION(S): Normal, eutopic, and ectopic endometrial biopsies as well as peritoneal fluid were obtained during surgery performed during the proliferative phase of the menstrual cycle. 12Z endometriotic epithelial cells were used for in vitro mechanistic studies. MAIN OUTCOME MEASURE(S): Tissue MRP4 mRNA levels were quantified by quantitative reverse-transcription polymerase chain reaction (qRT-PCR), and localization was analyzed with the use of immunohistochemistry. Cellular MRP4 mRNA and protein were quantified by qRT-PCR and Western blot, respectively. PGE(2) was measured in peritoneal fluid and cell supernatants using an enzyme immunoassay (EIA). RESULT(S): MRP4 was expressed in eutopic and ectopic endometrium, where it was overexpressed in peritoneal lesions and localized in the cytoplasm of glandular epithelial cells. LXA(4) attenuated MRP4 mRNA and protein levels in endometriotic epithelial cells in a dose-dependent manner, while not affecting the expression of enzymes involved in PGE(2) metabolism. Investigations employing receptor antagonists and small interfering RNA revealed that this occurred through estrogen receptor α. Accordingly, LXA(4) treatment inhibited extracellular PGE(2) release. CONCLUSION(S): We report for the first time that MRP4 is expressed in human endometrium, elevated in peritoneal endometriosis, and modulated by LXA(4) in endometriotic epithelial cells.

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The focus of this report is the regulation of complementary therapists and, as such, does not deal directly with the efficacy of such therapies. It is for the consumer to make the choice of which therapy they intend to use. Whether they wish to consult a qualified therapist such as a homeopath or an acupuncturist, a healer, the seventh son of a seventh son, a person reputed to have a cure for a particular ailment or a person with a special skill with bones; the choice is theirs. Read the report (PDF 607kb) Download the accompanying leaflet (PDF 300kb) Note – Re: Page 70. ASK Ireland wish to clarify that the Kinesiology Association of Ireland do not represent the Association of Systematic Kinesiology in Ireland, in any way.

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Cell separation, or abscission, is a highly specialized process in plants that facilitates remodeling of their architecture and reproductive success. Because few genes are known to be essential for organ abscission, we conducted a screen for mutations that alter floral organ shedding in Arabidopsis. Nine recessive mutations that block shedding were found to disrupt the function of an ADP-ribosylation factor-GTPase-activating protein (ARF-GAP) we have named NEVERSHED (NEV). As predicted by its homology to the yeast Age2 ARF-GAP and transcriptional profile, NEV influences other aspects of plant development, including fruit growth. Co-localization experiments carried out with NEV-specific antiserum and a set of plant endomembrane markers revealed that NEV localizes to the trans-Golgi network and endosomes in Arabidopsis root epidermal cells. Interestingly, transmission electron micrographs of abscission zone regions from wild-type and nev flowers reveal defects in the structure of the Golgi apparatus and extensive accumulation of vesicles adjacent to the cell walls. Our results suggest that NEV ARF-GAP activity at the trans-Golgi network and distinct endosomal compartments is required for the proper trafficking of cargo molecules required for cell separation.

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Résumé Régulation de l'expression de la Connexin36 dans les cellules sécrétrices d'insuline La communication intercellulaire est en partie assurée via des jonctions communicantes de type "gap". Dans la cellule ß pancréatique, plusieurs observations indiquent que le couplage assuré par des jonctions gap formées parla Connexine36 (Cx36) est impliqué dans le contrôle de la sécrétion de l'insuline. De plus, nous avons récemment démontré qu'un niveau précis d'expression de la Cx36 est nécessaire pour maintenir une bonne coordination de l'ensemble des cellules ß, et permettre ainsi une sécrétion synchrone et contrôlée d'insuline. Le développement du diabète et du syndrome métabolique est partiellement dû à une altération de la capacité des cellules ß à sécréter de l'insuline en réponse à une augmentation de la glycémie. Cette altération est en partie causée par l'augmentation prolongée des taux circulant de glucose, mais aussi de lipides, sous la forme d'acides gras libres, et de LDL (Low Density Lipoproteins), particules assurant le transport des acides gras et du cholestérol dans le sang. Nous avons étudié la régulation de l'expression de la Cx36 dans différentes conditions reflétant la physiopathologie du diabète de type 2 et du syndrome métabolique et démontré qu'une exposition prolongée à des concentrations élevées de glucose, de LDL, ainsi que de palmitate (acide gras saturé le plus abondant dans l'organisme), inhibent l'expression de la Cx36 dans les cellules ß. Cette inhibition implique l'activation de la PKA (Proteine Kinase A), qui stimule à son tour l'expression du facteur de transcription ICER-1 (Inductible cAMP Early Repressor-1). Ce puissant répresseur se fixe spécifiquement sur un motif CRE (cAMP Response Element), situé dans le promoteur du gène de la Cx36, inhibant ainsi son expression. Nous avons de plus démontré que des cytokines pro-inflammatoires, qui pourraient contribuer au développement du diabète, inhibent également l'expression de la Cx36. Cependant, les cytokines agissent indépendamment du répresseur ICER-1, mais selon un mécanisme requérant l'activation de l'AMPK (AMP dependant protein kinase). Sachant qu'un contrôle précis des niveaux d'expression de la Cx36 est un élément déterminant pour une sécrétion optimale de l'insuline, nos résultats suggèrent que la Cx36 pourrait être impliquée dans l'altération de la sécrétion de l'insuline contribuant à l'apparition du diabète de type 2. Summary A particular way by which cells communicate with each other is mediated by gap junctions, transmembrane structures providing a direct pathway for the diffusion of small molecules between adjacent cells. Gap junctional communication is required to maintain a proper functioning of insulin-secreting ß-cells. Moreover, the expression levels of connexin36 (Cx36), the sole gap junction protein expressed in ß-cells, are critical in maintaining glucose-stimulated insulin secretion. Chronic hyperglycemia and hyperlipidemia exert deleterious effects on insulin secretion and may contribute to the progressive ß-cell failure linked to the development of type 2 diabetes and metabolic syndrome. Since modulations of the Cx36 levels might impair ß-cell function, the general aim of this work was to elucidate wether elevated levels of glucose and lipids affect Cx36 expression. The first part of this work was dedicated to the study of the effect of high glucose concentrations on Cx36 expression. We demonstrated that glucose transcriptionally down-regulates the expression of Cx36 in insulin-secreting cells through activation of the protein kinase A (PKA), which in turn stimulates the expression of the inducible cAMP early repressor-1 (ICER-1). This repressor binds to a highly conserved cAMP response element (CRE) located in the Cx36 promoter, thereby inhibiting Cx36 expression. The second part of this thesis consisted in studying the effects of sustained exposure to free fatty acids (FFA) and human lipoproteins on Cx36 levels. The experiments revealed that the most abundant FFA, palmitate, as well as the atherogenic low density lipoproteins (LDL), also stimulate ICER-1 expression, resulting in Cx36 down-regulation. Finally, the third part of the work focused on the consequences of long-term exposure to proinflammatory cytokines on Cx36 content. Interleukin-1 ß (IL-1 ß) inhibits Cx36 expression and its effect is potentialized by tumor necrosis factor α (TNFα) and interferon γ (IFNγ). We further unveiled that the cytokines effect on Cx36 levels requires activation of the AMP dependent protein kinase (AMPK). Prolonged exposures to glucose, palmitate, LDL, and pro-inflammatory cytokines have all been proposed to contribute to the development of diabetes and metabolic syndrome. Since Cx36 expression levels are critical to maintain ß-cell function, Cx36 down-regulation by glucose, lipids, and cytokines might participate to the ß-cell failure associated with diabetes development.