Rangel D.E.N.,University of Paraiba Valley
World Journal of Microbiology and Biotechnology | Year: 2011
Prokaryotic and eukaryotic microbes thrive successfully in stressful environments such as high osmolarity, acidic or alkali, solar heat and u. v. radiation, nutrient starvation, oxidative stress, and several others. To live under these continuous stress conditions, these microbes must have mechanisms to protect their proteins, membranes, and nucleic acids, as well as other mechanisms that repair nucleic acids. The stress responses in bacteria are controlled by master regulators, which include alternative sigma factors, such as RpoS and RpoH. The sigma factor RpoS integrates multiple signals, such as the general stress response regulators and the sigma factor RpoH regulates the heat shock proteins. These response pathways extensively overlap and are induced to various extents by the same environmental stresses. In eukaryotes, two major pathways regulate the stress responses: stress proteins, termed heat shock proteins (HSP), which appear to be required only for growth during moderate stress, and stress response elements (STRE), which are induced by different stress conditions and these elements result in the acquisition of a tolerant state towards any stress condition. In this review, the mechanisms of stress resistance between prokaryotic and eukaryotic microbes will be described and compared. © 2010 Springer Science+Business Media B.V.
Lopes C.O.,University of Paraiba Valley
International Journal of Radiation Oncology Biology Physics | Year: 2012
Purpose: To investigate the effect of radiotherapy (RT) on serum levels of interleukin-2 (IL-2), IL-4, IL-5, IL-6, tumor necrosis factor alpha (TNF-α), macrophage inflammatory protein-1-alpha (MIP-1-α) and leukemia inhibitory factor (LIF) in patients with prostate cancer. Methods and Materials: Forty eight patients with prostate cancer received three-dimensional conformal blocking radiation therapy with a linear accelerator. IL-2, IL-4, IL-5, IL-6, TNF-α, MIP-1-α, and LIF levels were measured by the related immunoassay kit 1 day before the beginning of RT and during RT at days 15 and 30. Results: The mean IL-2 values were elevated before and during the RT in contrast with those of IL-4, IL-5, IL-6, TNF-α, MIP-1-α, and LIF, which were within the normal range under the same conditions. Regarding markers IL-2, IL-4, IL-5, TNF-α, MIP-1-α, and LIF, comparisons among the three groups (before treatment and 15 and 30 days during RT) did not show significant differences. Although values were within the normal range, there was a significant rise in IL-6 levels at day 15 of RT (p = 0.0049) and a decline at day 30 to levels that were similar to those observed before RT. Conclusions: IL-6 appeared to peak after 15 days of RT before returning to pre-RT levels. In contrast, IL-2, IL-4, IL-5, TNF-α, MIP-1-α, and LIF levels were not sensitive to irradiation. The increased levels of IL-6 following RT without the concurrent elevation of other cytokines involved in the acute phase reaction did not suggest a classical inflammatory response to radiation exposure. Further studies should be designed to elucidate the role of IL-6 levels in patients with prostate cancer treated with RT. Copyright © 2012 Elsevier Inc. Printed in the USA. All rights reserved.
Muella M.T.A.H.,University of Paraiba Valley |
de Paula E.R.,National Institute for Space Research |
Jonah O.F.,National Institute for Space Research
Surveys in Geophysics | Year: 2014
In this work, the climatology of ionospheric scintillations at global positioning system (GPS) L-band frequency and the zonal drift velocities of scintillation-producing irregularities were depicted for the equatorial observatory of São Luis (2.33°S; 44.21°W; dip latitude 1.3°S), Brazil. This is the first time that the hourly, monthly, and seasonal variations of scintillations and irregularity zonal drifts at São Luis were characterized during periods of different solar activity levels (from December 1998 to February 2007). The percentage occurrence of scintillations at different sectors of the sky was also investigated, and the results revealed that the scintillations are more probable to be observed in the west sector of the sky above São Luis, whereas the north-south asymmetries are possibly related to asymmetries in the plasma density distribution at off-equatorial latitudes. The scintillations on GPS signals occurred more frequently around solar maximum years, but it is also clear from the results of a strong variability in the scintillation activity in the years with moderate solar flux during the descending phase of the solar cycle. The equatorial scintillations occur predominantly during pre-midnight hours with a broad maximum near the December solstice months. In general, weak level of scintillations (S 4 index between 0.2 and 0.4) dominated at all seasons; however, during the winter months around solar maximum years (although the scintillation occurrence is extremely low), stronger levels of scintillations (S 4 > 0.6) may occur at comparable rate with the weak scintillations. The irregularity zonal velocities, as estimated from the GPS spaced-receiver technique, presented a different scenario for the two seasons analyzed; during the equinoxes, the magnitude of the zonal velocities appeared not to change with the solar activity, whereas during the December solstice months, the larger magnitudes were observed around solar maximum years. Other relevant aspects of the observations are highlighted and discussed. © 2013 Springer Science+Business Media Dordrecht.
Nascimento S.B.,University of Paraiba Valley
Photomedicine and laser surgery | Year: 2010
OBJECTIVE: To investigate the healing of bone defects in male rats treated with salmon calcitonin, low-level laser therapy (LLLT), or both. BACKGROUND: Healing of bone defects still represents a challenge to health professionals in several areas. In this article, the effect of calcitonin in combination with LLLT on bone repair was studied. Densitometry was used as a valuable tool for the measurement of bone regeneration. METHODS: Sixty male Wistar rats underwent bilateral castration surgery before the creation of a surgical bone defect. The animals were randomly divided into four groups: control, treated with calcitonin (Ca), treated with LLLT (La), and treated with calcitonin and LLLT (CaLa). Groups Ca and CaLa received 2 IU/kg of synthetic salmon calcitonin intramuscularly three times a week. Groups La and CaLa received laser therapy using a gallium-aluminum-arsenide laser (10 mW, 20 J/cm(2), wavelength 830 nm). Control animals were submitted to sham irradiation. The animals were sacrificed 7, 14, and 21 days after surgery, and bone defects were analyzed using densitometry. RESULTS: The CaLa group had a higher degree of bone regeneration 14 and 21 days after surgery. CONCLUSIONS: The La and CaLa had significantly higher bone mineral density than the control and Ca groups.
Oyekola O.S.,307 143 Eighth Street |
Fagundes P.R.,University of Paraiba Valley
Earth, Planets and Space | Year: 2012
Observations of the F2-layer critical frequency (f 0F2), peak height F2-layer (hmF 2) and propagation factor (M3000F2) recorded near dip-equator Ouagadougou, Burkina Faso (12.4°N, 358.5°E; dip latitude: 1.5°N) have been validated against the International Reference Ionosphere (IRI-2007) model during low (1987) and high (1990) solar activity and undisturbed conditions for four different seasons, with a view to enhance the predictability of the IRI. The results illustrated that URSI option for h mF2 and CCIR option for M3000F2 portray remarkably well the morphological trends and replicate mostly the diurnal salient features of the experimental data at low and high solar activity periods. In contrast, both URSI and CCIR models of f0F2 also reproduce diurnal and seasonal patterns and outstanding features of observational data surprisingly well for solar minimum conditions except July; whereas we found considerable disparities between model and data during solar cycle maximum. The total model error ranging from approximately 6-8% (h mF2), 13-38% (fQF2) and 8-29% (hmF2), 12-44% (f0F2), respectively for low and high flux year, but roughly comparable at 3-7% for M 3000F2 at low and high solar activity. Our observations indicate higher values of foF2 deviations compared to prior calculated differences obtained for the low-latitude region over Indian and Asian. Copyright © The Society of Geomagnetism and Earth, Planetary and Space Sciences (SGEPSS).