957 resultados para frequency response functions
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Anuran amphibians are known to exhibit an intermittent pattern of pulmonary ventilation and to exhibit an increased ventilatory response to hypoxia and hypercarbia. However, only a few species have been studied to date. The aquatic frog Pipa carvalhoi inhabits lakes, ponds and marshes that are rich in nutrients but low in O-2. There are no studies of the respiratory pattern of this species and its ventilation during hypoxia or hypercarbia. Accordingly, the aim of the present study was to characterize the breathing pattern and the ventilatory response to aquatic and aerial hypoxia and hypercarbia in this species. With this purpose, pulmonary ventilation (V-1) was directly measured by the pneumotachograph method during normocapnic normoxia to determine the basal respiratory pattern and during aerial and aquatic hypercarbia (5% CO2) and hypoxia (5% O-2). Our data demonstrate that P. carvalhoi exhibits a periodic breathing pattern composed of single events (single breaths) of pulmonary ventilation separated by periods of apnea. The animals had an enhanced V-1 during aerial hypoxia, but not during aquatic hypoxia. This increase was strictly the result of an increase in the breathing frequency. A pronounced increase in V-1 was observed if the animals were simultaneously exposed to aerial and aquatic hypercarbia, whereas small or no ventilatory responses were observed during separately administered aerial or aquatic hypercarbia. P. carvalhoi primarily inhabits an aquatic environment. Nevertheless, it does not respond to low O-2 levels in water, although it does so in air. The observed ventilatory responses to hypercarbia may indicate that this species is similar to other anurans in possessing central chemoreceptors. (C) 2012 Elsevier Inc. All rights reserved.
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The course of leprosy depends of the host immune response which ranges from the lepromatous pole (LL) to the tuberculoid pole (TT). A comparative study was conducted in 60 patients with the LL and TT The results showed a mean expression of TGF-beta of 339 +/- 99.4 cells/field for TT and of 519.2 +/- 68.2 cells/field for LL. Frequency of apoptosis was 6.3 +/- 1.8 in TT and 14.0 +/- 6.1 in LL. A correlation (p = 0.0251) between TGF-beta and caspase-3 in the LL was found. This finding indicates a role of TGF-beta and apoptosis in the immune response in leprosy. (C) 2012 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.
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Background: Imatinib mesylate (IM) is a selective tyrosine kinase inhibitor used for treating chronic myeloid leukemia (CML). IM has high efficacy, however some individuals develop a resistance due to impaired bio-availability. Polymorphisms in genes encoding membrane transporters such as ABCB1 have been associated with differences in protein expression and function that influence the response to several drugs. Aim: To investigate the relationship of ABCB1 polymorphisms with markers of response to IM in patients with CML Methods: One hundred eighteen CML patients initially treated with a standard dose of IM (400 mg/day) for 18 months were selected at two health centers in Sao Paulo City, Brazil. The response criteria were based on the European LeukemiaNet recommendations. ABCB1 polymorphisms c.1236C>T (rs1128503), c.3435C>T (rs1045642) and c.2677G>T/A (rs2032582) were evaluated by PCR-RFLP. Results: ABCB1 polymorphisms were not related with a risk for CML in this sample population (p<0.05). In the CML group, frequencies of ABCB1 SNPs were similar between responder and non-responder patients (p>0.05). In the responder group, the frequency of ABCB11236CT/2677GT/3435CT haplotype was higher in patients with major molecular response (MMR) (51.7%) than in patients without MMR (8.3%, p = 0.010). Furthermore, carriers of this haplotype had increased the probability of reaching the MMR compared with the non-carriers (OR: 11.8; 95% CI: 1.43-97.3, p = 0.022). Conclusions: The ABCB1 1236CT/2677GT/3435CT haplotype is positively associated with the major molecular response to IM in CML patients. (C) 2011 Elsevier Inc. All rights reserved.
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Methods. One hundred and twenty patients (RA, n = 41; AS, n = 57; PsA, n = 22) on anti-TNF agents (monoclonal, n = 94; soluble receptor, n = 26) were compared with 116 inflammatory arthritis patients under DMARDs and 117 healthy controls. Seroprotection, seroconversion (SC), geometric mean titre, factor increase in geometric mean titre and adverse events were evaluated 21 days after vaccination. Results. After immunization, SC rates (58.2% vs 74.3%, P = 0.017) were significantly lower in SpA patients receiving anti-TNF therapy, whereas no difference was observed in RA patients receiving this therapy compared with healthy controls (P = 0.067). SpA patients receiving mAbs (infliximab/adalimumab) had a significantly lower SC rate compared with healthy controls (51.6% vs 74.3%, P = 0.002) or those on DMARDs (51.6% vs 74.7%, P = 0.005), whereas no difference was observed for patients on etanercept (86.7% vs 74.3%, P = 0.091). Further analysis of non-seroconverting and seroconverting SpA patients revealed that the former group had a higher mean age (P = 0.003), a higher frequency of anti-TNF (P = 0.031) and mAbs (P = 0.001) and a lower frequency of MTX (P = 0.028). In multivariate logistic regression, only older age (P = 0.015) and mAb treatment (P = 0.023) remained significant factors for non-SC in SpA patients. Conclusion. This study revealed a distinct disease pattern of immune response to the pandemic influenza vaccine in inflammatory arthritis patients receiving anti-TNF agents, illustrated by a reduced immunogenicity solely in SpA patients using mAbs. Trial Registration: ClinicalTrials.gov, ext-link-type="uri" xlink:href="www.clinicaltrials.gov" xmlns:xlink="http://www.w3.org/1999/xlink">www.clinicaltrials.gov, NCT01151644.
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procera (pro) is a tall tomato (Solanum lycopersicum) mutant carrying a point mutation in the GRAS region of the gene encoding SlDELLA, a repressor in the gibberellin (GA) signaling pathway. Consistent with the SlDELLA loss of function, pro plants display a GA-constitutive response phenotype, mimicking wild-type plants treated with GA(3). The ovaries from both nonemasculated and emasculated pro flowers had very strong parthenocarpic capacity, associated with enhanced growth of preanthesis ovaries due to more and larger cells. pro parthenocarpy is facultative because seeded fruits were obtained by manual pollination. Most pro pistils had exserted stigmas, thus preventing self-pollination, similar to wild-type pistils treated with GA(3) or auxins. However, Style2.1, a gene responsible for long styles in noncultivated tomato, may not control the enhanced style elongation of pro pistils, because its expression was not higher in pro styles and did not increase upon GA(3) application. Interestingly, a high percentage of pro flowers had meristic alterations, with one additional petal, sepal, stamen, and carpel at each of the four whorls, respectively, thus unveiling a role of SlDELLA in flower organ development. Microarray analysis showed significant changes in the transcriptome of preanthesis pro ovaries compared with the wild type, indicating that the molecular mechanism underlying the parthenocarpic capacity of pro is complex and that it is mainly associated with changes in the expression of genes involved in GA and auxin pathways. Interestingly, it was found that GA activity modulates the expression of cell division and expansion genes and an auxin signaling gene (tomato AUXIN RESPONSE FACTOR7) during fruit-set.
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This study investigated whether perinatal exposure to picrotoxin, a GABA(A) antagonist, modifies the effect of muscimol, a GABA(A) agonist, on the sexual behavior of adult male rats. Two hours after birth and then once daily during the next 9 days of lactation, dams received picrotoxin (0.75 mg/kg subcutaneously) or saline (1 ml/kg subcutaneously). The adult male offspring from the picrotoxin and saline groups received saline (1 ml/kg intraperitoneally) or muscimol (1 mg/kg intraperitoneally), and 15 min later, their sexual behavior was assessed. Muscimol treatment in the saline-exposed group increased the mount and intromission latencies. However, these effects were absent in the picrotoxin-exposed groups. The latencies to first ejaculation, postejaculatory mount, and intromission were decreased in both picrotoxin-exposed groups relative to the saline-exposed groups. The picrotoxin + muscimol-treated rats required more intromissions to ejaculate and the picrotoxin-exposed groups made more ejaculations than the saline-exposed groups. Thus, muscimol treatment did not increase the mount and intromission latencies following picrotoxin exposure, but increased the ejaculation frequency, which did not differ between the picrotoxin + muscimol and the picrotoxin + saline groups. These data indicate that perinatal picrotoxin treatment interfered with GABA(A) receptor development Behavioural Pharmacology 23:703-709 (c) 2012 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins.
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A new methodology for the synthesis of tunable patch filters is presented. The methodology helps the designer to perform a theoretical analysis of the filter through a coupling matrix that includes the effect of the tuning elements used to tune the filter. This general methodology accounts for any tuning parameter desired and was applied to the design of a tunable dual-mode patch filter with independent control of center frequency and bandwidth (BW). The bandpass filter uses a single triangular resonator with two etched slots that split the fundamental degenerate modes and form the filter passband. Varactor diodes assembled across the slots are used to vary the frequency of each degenerate fundamental mode independently, which is feasible due to the nature of the coupling scheme of the filter. The varactor diode model used in simulations, their assembling, the dc bias configuration, and measured results are presented. The theory results are compared to the simulations and to measurements showing a very good agreement and validating the proposed methodology. The fabricated filter presents an elliptic response with 20% of center frequency tuning range around 3.2 GHz and a fractional BW variation from 4% to 12% with low insertion loss and high power handling with a 1-dB compression point higher than +14.5 dB.
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Objectives: To establish normative amplitude values for relative difference measurements of the middle latency response (MLR) in normal-hearing pediatrics and to determine if these measurements provided a significant reduction of within-group variability when compared to raw, absolute amplitude measures. A relative amplitude difference is defined in the present paper as the difference in Na-Pa amplitude between two electrodes (e.g. vertical bar Na-Pa at C3 minus Na-Pa at C4 vertical bar, or electrode effects) or between two ears (e.g. vertical bar Na-Pa on left ear stimulation minus Na-Pa on right ear stimulation vertical bar, or ear effects). In contrast, an absolute amplitude is defined as a single Na-Pa measurement made at one electrode for stimulation of one ear (e.g. Na-Pa measured at C3 on left ear stimulation). Design: Cross-sectional study. Study sample: 155 pediatrics with normal peripheral and central hearing, and no history of psychological, neurological, or learning disability issues. Results: Within-group variability was significantly smaller for relative differences when compared to absolute amplitude measures. Electrode effects showed significantly less variability than ear effects. Normative values for ear and electrode effects were reported. Conclusions: Relative differences may provide better utility in the clinical diagnosis of central auditory pathology in pediatrics when compared to absolute amplitude measures because these difference measures show significantly lower variability when examined across subjects.
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Frequency-dependent electroluminescence and electric current response spectroscopy were applied to polymeric light-emitting electrochemical cells in order to obtain information about the operation mechanism regimes of such devices. Three clearly distinct frequency regimes could be identified: a dielectric regime at high frequencies; an ionic transport regime, characterized by ionic drift and electronic diffusion; and an electrolytic regime, characterized by electronic injection from the electrodes and electrochemical doping of the conjugated polymer. From the analysis of the results, it was possible to evaluate parameters like the diffusion speed of electronic charge carriers in the active layer and the voltage drop necessary for operation. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4752438]
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The medullary raphe (MR) is a putative central chemoreceptor site, contributing to hypercapnic respiratory responses elicited by changes in brain PCO2/pH. Purinergic mechanisms in the central nervous system appear to contribute to central chemosensitivity. To further explore the role of P2 receptors within the rostral and caudal MR in relation to respiratory control in room air and hypercapnic conditions, we performed microinjections of PPADS, a non-selective P2X antagonist, in conscious rats. Microinjections of PPADS into the rostral or caudal MR produced no changes in the respiratory frequency, tidal volume and ventilation in room air condition. The ventilatory response to hypercapnia was attenuated after microinjection of PPADS into the rostral but not in the caudal MR when compared to the control group (vehicle microinjection). These data suggest that P2X receptors in the rostral MR contribute to the ventilatory response to CO2, but do not participate in the tonic maintenance of ventilation under room air condition in conscious rats. (C) 2012 Elsevier B.V. All rights reserved.
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Objectives The aim of the present paper is to evaluate the immune response and tolerability of varicella vaccine in children and adolescents with systemic lupus erythematosus previously exposed to varicella-zoster virus. Methods We performed a prospective and controlled study on a group of 54 SLE patients that were chosen at random to be or not to be vaccinated (28 were vaccinated and 26 were not). Twenty-eight healthy controls, of matching age and sex were also vaccinated. All were submitted to a questionnaire, physical evaluation and laboratory assays: lymphocyte immuno-phenotyping by flow cytometry, plasma varicella zoster virus (VZV) serology by ELISA and in vitro interferon gamma (IFN gamma) production by T-cells after stimulus with VZV antigen. They were evaluated before vaccination and at 30, 45, 180 and 360 days afterwards. Results We did not observe any differences in the frequency of adverse events in both vaccinated groups. At study entry, all individuals were seropositive for VZV antibodies. The serum VZV antibody titres similarly increased after vaccination. The frequency of flares and the SLEDAI score were also similar among the patients. Thirty days after vaccination the production of IFN gamma specific to VZV was lower in the SLE group compared to healthy, controls. In the follow-up we observed 4 cases of herpes zoster in the SLE unvaccinated group, but no zoster in the vaccinated group. Conclusion The varicella vaccine was well tolerated in SLE group, who had pre-existing immunity to varicella. The varicella vaccine immunogenicity measurement by serum antibody titres was appropriate. The incidence of HZ was lower in the vaccinated lupus group.
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The frequency of anointing bouts and the materials used for self- and social anointing vary across capuchin species in captivity, but there is little published data on capuchin anointing in the wild. Here we present previously unpublished data on anointing behaviors from capuchin monkey populations at ten different field sites and incorporate these data into a review of the anointing literature for captive and wild capuchins. Using a comparative phylogenetic framework, we test four hypotheses derived primarily from captive literature for variation in anointing between wild untufted capuchins (Cebus) and tufted capuchins (Sapajus), including that (1) the frequency of anointing is higher in Cebus, (2) Cebus uses a higher proportion of plant species to insect species for anointing compared with Sapajus, (3) anointing material diversity is higher in Cebus, and (4) social indices of anointing are higher in Cebus. We found that wild Cebus anoints more with plant parts, including fruits, whereas wild Sapajus anoints more with ants and other arthropods. Cebus capucinus in particular uses more plant species per site for anointing compared with other capuchins and may specialize in anointing as an activity independent from foraging, whereas most other capuchin species tend to eat the substances they use for anointing. In agreement with captive studies, we found evidence that wild Cebus anoints at a significantly higher frequency than Sapajus. However, contrary to the captive literature, we found no difference in the range of sociality for anointing between Cebus and Sapajus in the wild. We review anointing in the context of other Neotropical primate rubbing behaviors and consider the evidence for anointing as self-medication; as a mechanism for enhanced sociality; and as a behavioral response to chemical stimuli. Am. J. Primatol. 74:299314, 2012. (c) 2011 Wiley Periodicals, Inc.
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This study investigated whether there are differences in the Speech-Evoked Auditory Brainstem Response among children with Typical Development (TD), (Central) Auditory Processing Disorder (C) APD, and Language Impairment (LI). The speech-evoked Auditory Brainstem Response was tested in 57 children (ages 6-12). The children were placed into three groups: TD (n = 18), (C)APD (n = 18) and LI (n = 21). Speech-evoked ABR were elicited using the five-formant syllable/da/. Three dimensions were defined for analysis, including timing, harmonics, and pitch. A comparative analysis of the responses between the typical development children and children with (C)APD and LI revealed abnormal encoding of the speech acoustic features that are characteristics of speech perception in children with (C)APD and LI, although the two groups differed in their abnormalities. While the children with (C)APD might had a greater difficulty distinguishing stimuli based on timing cues, the children with LI had the additional difficulty of distinguishing speech harmonics, which are important to the identification of speech sounds. These data suggested that an inefficient representation of crucial components of speech sounds may contribute to the difficulties with language processing found in children with LI. Furthermore, these findings may indicate that the neural processes mediated by the auditory brainstem differ among children with auditory processing and speech-language disorders. (C) 2012 Elsevier B.V. All rights reserved.
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Background: Cytotoxic T lymphocyte-associated factor 4 (CTLA-4) functions as a negative regulator of T cell-mediated immune response. Molecular changes associated to CTLA-4 gene polymorphisms could reduce its ability to suppress and control lymphocyte proliferation. Aims: To evaluate the frequency of CTLA-4 gene polymorphisms in chronic hepatitis C virus (HCV) infected patients and correlate to clinical and histological findings. Methods: We evaluated 112 HCV-infected subjects prospectively selected and 183 healthy controls. Clinical and liver histological data were analysed. - 318C > T, A49G and CT60 CTLA-4 single-nucleotide polymorphisms (SNPs) were studied by PCR-RFLP and AT(n) polymorphism by DNA fragment analysis by capillary electrophoresis in automatic sequencer. Results: Eight AT repetitions in 3' UTR region were more frequent in HCV-infected subjects. We found a positive association of -318C and + 49G with HCV genotype 3 (P = 0.008, OR 9.13, P = 0.004, OR 2.49 respectively) and an inverse association of both alleles with HCV genotype 1 (P = 0.020, OR 0.19, P = 0.002, OR 0.38 respectively). Allele + 49G was also associated to aminotransferases quotients > 3 (qALT, P = 0.034, qAST, P = 0.041). Allele G of CT60 SNP was also associated with qAST > 3 (P = 0.012). Increased number of AT repetitions was positively associated to severe necroinflammatory activity scores in liver biopsies (P = 0.045, OR 4.62). Conclusion: CTLA-4 gene polymorphisms were associated to HCVinfection. Eight AT repetitions were more prevalent in HCV-infected subjects. - 318C and + 49G alleles were associated to genotypes 1 and 3 infections and increased number of AT repetitions in 3' UTR region favoured severe necroinflammatory activity scores in liver biopsies.
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This was a cross-sectional study which analyzed the prevalence and the clinical and immunological spectrum of canine Leishmania (L.) infantum chagasi infection in a cohort of 320 mongrel dogs living in an endemic area of American visceral leishmaniasis in the Amazonian Brazil by using, mainly, the indirect fluorescence antibody test (IFAT-IgG) and the delayed-type hypersensitivity (DTH), and the parasite research by the popliteal lymph node aspiration. The IFAT and DTH reactivity recognized three different immune response profiles: (1) IFAT((+))/DTH(-) (107 dogs), (2) IFAT((-))/DTH(+) (18 dogs), and (3) IFAT((+))/DTH(+) (13 dogs), providing an overall prevalence of infection of 43 % (138/320). Thus, the specific prevalence of IFAT ((+)) /DTH ((-)) 33.4 % (107/320) was higher than those of IFAT ((-)) /DTH ((+)) 5.6 % (18/320) and IFAT ((+)) /DTH ((+)) 4.0 % (13/320). Moreover, the frequency of these profiles among 138 infected dogs showed that the IFAT ((+)) /DTH ((-)) rate of 77.5 % (107/138) was also higher than those of 13.0 % (18/138) of IFAT ((-)) /DTH ((+)) and 9.5 % (13/138) of IFAT ((+)) /DTH ((+)) rates. The frequency of asymptomatic dogs (76 %-105) was higher than those of symptomatic (16.6 %-23) and oligosymptomatic ones (7.4 %-10). A total of 16 (11.6 %) L. (L.) i. chagasi isolates were obtained from infected dogs, all from the IFAT ((+)) /DTH ((-)) profile: 41 % (9/22) from symptomatic, 33.3 % (3/9) from oligosymptomatic, and 5.2 % (4/76) from asymptomatic dogs. These findings strongly suggested that despite the higher frequency of asymptomatic dogs (76 %-105), the majority (72.4 %-76) was characterized by the IFAT ((+)) /DTH ((-)) profile with a doubtful immunogenetic resistance against infection.