Brainstem oxytocinergic modulation of heart rate control in rats: effects of hypertension and exercise training

Oxytocinergic brainstem projections participate in the autonomic control of the circulation. We investigated the effects of hypertension and training on cardiovascular parameters after oxytocin (OT) receptor blockade within the nucleus tractus solitarii (NTS) and NTS OT and OT receptor expression. Male spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats were trained (55% of maximal exercise capacity) or kept sedentary for 3 months and chronically instrumented (NTS and arterial cannulae). Mean arterial blood pressure (MAP) and heart rate (HR) were measured at rest and during an acute bout of exercise after NTS pretreatment with vehicle or OT antagonist (20 pmol of OT antagonist (200 nl of vehicle)-1). Oxytocin and OT receptor were quantified (35S-oligonucleotide probes, in situ hybridization) in other groups of rats. The SHR exhibited high MAP and HR (P < 0.05). Exercise training improved treadmill performance and reduced basal HR (on average -11%) in both groups, but did not change basal MAP. Blockade of NTS OT receptor increased exercise tachycardia only in trained groups, with a larger effect on trained WKY rats (+31 +/- 9 versus +12 +/- 3 beats min-1 in the trained SHR). Hypertension specifically reduced NTS OT receptor mRNA density (-46% versus sedentary WKY rats, P < 0.05); training did not change OT receptor density, but significantly increased OT mRNA expression (+2.5-fold in trained WKY rats and +15% in trained SHR). Concurrent hypertension- and training-induced plastic (peptide/receptor changes) and functional adjustments (HR changes) of oxytocinergic control support both the elevated basal HR in the SHR group and the slowing of the heart rate (rest and exercise) observed in trained WKY rats and SHR.

Statistical analysis of the Doppler broadening coincidence spectrum of electron-positron annihilation radiation in silicon

We report a statistical analysis of Doppler broadening coincidence data of electron-positron annihilation radiation in silicon using a (22)Na source. The Doppler broadening coincidence spectrum was fit using a model function that included positron annihilation at rest with 1s, 2s, 2p, and valence band electrons. In-flight positron annihilation was also fit. The response functions of the detectors accounted for backscattering, combinations of Compton effects, pileup, ballistic deficit, and pulse-shaping problems. The procedure allows the quantitative determination of positron annihilation with core and valence electron intensities as well as their standard deviations directly from the experimental spectrum. The results obtained for the core and valence band electron annihilation intensities were 2.56(9)% and 97.44(9)%, respectively. These intensities are consistent with published experimental data treated by conventional analysis methods. This new procedure has the advantage of allowing one to distinguish additional effects from those associated with the detection system response function. (C) 2009 Elsevier B.V. All rights reserved.

Search for first harmonic modulation in the right ascension distribution of cosmic rays detected at the Pierre Auger Observatory

We present the results of searches for dipolar-type anisotropies in different energy ranges above 2.5 x 10(17) eV with the surface detector array of the Pierre Auger Observatory, reporting on both the phase and the amplitude measurements of the first harmonic modulation in the right-ascension distribution. Upper limits on the amplitudes are obtained, which provide the most stringent bounds at present, being below 2% at 99% C.L. for EeV energies. We also compare our results to those of previous experiments as well as with some theoretical expectations. (C) 2011 Elsevier B.V. All rights reserved.

The Pierre Auger Observatory scaler mode for the study of solar activity modulation of galactic cosmic rays

Since data-taking began in January 2004, the Pierre Auger Observatory has been recording the count rates of low energy secondary cosmic ray particles for the self-calibration of the ground detectors of its surface detector array. After correcting for atmospheric effects, modulations of galactic cosmic rays due to solar activity and transient events are observed. Temporal variations related with the activity of the heliosphere can be determined with high accuracy due to the high total count rates. In this study, the available data are presented together with an analysis focused on the observation of Forbush decreases, where a strong correlation with neutron monitor data is found.

Glypican-3 regulates migration, adhesion and actin cytoskeleton organization in mammary tumor cells through Wnt signaling modulation

Glypican-3 (GPC3) is a proteoglycan involved in migration, proliferation and cell survival modulation in several tissues. There are many reports demonstrating a downregulation of GPC3 expression in some human tumors, including mesothelioma, ovarian and breast cancer. Previously, we determined that GPC3 reexpression in the murine mammary adenocarcinoma LM3 cells induced an impairment of their in vivo invasive and metastatic capacities together with a higher susceptibility to in vitro apoptosis. Currently, the signaling mechanism of GPC3 is not clear. First, it was speculated that GPC3 regulates the insulin-like growth factor (IGF) signaling system. This hypothesis, however, has been strongly challenged. Recently, several reports indicated that at least in some cell types GPC3 serves as a selective regulator of Wnt signaling. Here we provide new data demonstrating that GPC3 regulates Wnt pathway in the metastatic adenocarcinoma mammary LM3 cell line. We found that GPC3 is able to inhibit canonical Wnt signals involved in cell proliferation and survival, as well as it is able to activate non canonical pathway, which directs cell morphology and migration. This is the first report indicating that breast tumor cell malignant properties can be reverted, at least in part, by GPC3 modulation of Wnt signaling. Our results are consistent with the potential role of GPC3 as a metastasis suppressor.

Chlorella vulgaris up-modulation of myelossupression induced by lead: The role of stromal cells

In this study, Chlorella vulgaris (CV) was examined for its chelating effects on the ability of bone marrow stromal cell layer to display myeloid progenitor cells in vitro in lead-exposed mice, using the long-term bone marrow culture (LTBMC). In addition, the levels of interleukin (IL)-6, an important hematopoietic stimulator, as well as the numbers of adherent and non-adherent cells were also investigated. Mice were gavage treated daily with a single 50 mg/kg dose of CV for 10 days, concomitant to continuous offering of 1300 ppm lead acetate in drinking water. We found that CV up-modulates the reduced ability of stromal cell layer to display myeloid progenitor cells in vitro in lead-exposed mice and restores both the reduced number of non-adherent cells and the ability of stromal cells from these mice to produce IL-6. Monitoring of lead poisoning demonstrated that CV treatment significantly reduced lead levels in blood and tissues, completely restored the normal hepatic ALA levels, decreased the abnormally high plasma ALA and partly recovered the liver capacity to produce porphyrins. These findings provide evidence for a beneficial use of CV for combination or alternative chelating therapy to protect the host from the damage induced by lead poisoning. (C) 2008 Elsevier Ltd. All rights reserved.

Modulation of trans-to-cis photoisomerization and photoluminescence of 1,2-bis(4-pyridyl)ethylene or 4-styrylpyridine coordinated to fac-tricarbonyl(5-chloro-1,10-phenathroline)rhenium(I)

Photochemical and photophysical properties of fac-[Re(CO)(3)(Clphen)(trans-L)](+) complexes, Clphen = 5-chloro-1,10-phenathroline and L = 1,2-bis(4-pyridyl)ethylene, bpe, or 4-styrylpyridine, stpy, were investigated to complement the understanding of intramolecular energy transfer process in tricarbonyl rhenium(I) complexes having an electron withdrawing group attached to polypyridyl ligands. These new compounds were synthesized, characterized and the photoisomerization quantum yields were accurately determined by (1)H NMR spectroscopy. The true quantum yields for fac-[Re(CO)(3)(Clphen) (trans-bpe)](+) were constant (Phi = 0.55) at all investigated irradiation wavelengths. However, for fac-[Re(CO)(3)(Clphen)(trans-stpy)](+), similar true quantum yields were observed only at higher energy irradiation (Phi(313 nm) = 0.53 and Phi(365 nm) = 0.57), but it decreased significantly at 404 nm (Phi = 0.41). These results indicated different deactivation pathways for the trans-stpy complex photoisomerization. Quantum yields decreased as the (3)IL(trans-L) and (3)MLCT(Re -> NN) excited states become closer and the behavior was discussed in terms of the excited state energy gaps. Additionally, luminescence properties of photoproducts, fac-[Re(CO)(3)(Clphen)(cis-L)](+), were also investigated in different environments to analyze the relative energy of the (3)MLCT(Re -> Clphen) excited state for each compound. (C) 2011 Elsevier B.V. All rights reserved.