High salt intake activates the hypothalamic-pituitary-adrenal axis, amplifies the stress response, and alters tissue glucocorticoid exposure in mice

Aims: High salt intake is common and contributes to poor cardiovascular health. Urinary sodium excretion correlates directly with glucocorticoid excretion in humans and experimental animals. We hypothesized that high salt intake activates the hypothalamic-pituitary-adrenal axis activation and leads to sustained glucocorticoid excess. Methods and results: In male C57BL/6 mice, high salt intake for 2-8 weeks caused an increase in diurnal peak levels of plasma corticosterone. After 2 weeks, high salt increased Crh and Pomc mRNA abundance in the hypothalamus and anterior pituitary, consistent with basal hypothalamic-pituitary-adrenal axis activation. Additionally, high salt intake amplified glucocorticoid response to restraint stress, indicative of enhanced axis sensitivity. The binding capacity of Corticosteroid-Binding Globulin was reduced and its encoding mRNA downregulated in the liver. In the hippocampus and anterior pituitary, Fkbp5 mRNA levels were increased, indicating increased glucocorticoid exposure. The mRNA expression of the glucocorticoid-regenerating enzyme, 11β-hydroxysteroid dehydrogenase Type 1, was increased in these brain areas and in the liver. Sustained high salt intake activated a water conservation response by the kidney, increasing plasma levels of the vasopressin surrogate, copeptin. Increased mRNA abundance of Tonebp and Avpr1b in the anterior pituitary suggested that vasopressin signalling contributes to hypothalamic-pituitary-adrenal axis activation by high salt diet. Conclusion: Chronic high salt intake amplifies basal and stress-induced glucocorticoid levels and resets glucocorticoid biology centrally, peripherally and within cells.</p

An ultra-wide bandwidth (704 to 4 032 MHz) receiver for the Parkes radio telescope

We describe an ultra-wide-bandwidth, low-frequency receiver recently installed on the Parkes radio telescope. The receiver system provides continuous frequency coverage from 704 to 4032 MHz. For much of the band ( ${∼}60$ ), the system temperature is approximately 22 K and the receiver system remains in a linear regime even in the presence of strong mobile phone transmissions. We discuss the scientific and technical aspects of the new receiver, including its astronomical objectives, as well as the feed, receiver, digitiser, and signal processor design. We describe the pipeline routines that form the archive-ready data products and how those data files can be accessed from the archives. The system performance is quantified, including the system noise and linearity, beam shape, antenna efficiency, polarisation calibration, and timing stability

In situ quantitative analysis of individual H2O–CO2 fluid inclusions by laser Raman spectroscopy

Raman spectral parameters for the Raman ν1 (1285 cm−1) and 2ν2 (1388 cm−1) bands for CO2 and for the O–H stretching vibration band of H2O (3600 cm−1) were determined in H2O–CO2 fluid inclusions. Synthetic fluid inclusions containing 2.5 to 50 mol% CO2 were analyzed at temperatures equal to or greater than the homogenization temperature. The results were used to develop an empirical relationship between composition and Raman spectral parameters. The linear peak intensity ratio ( IR=ICO2 / ( ICO2+IH2O)) is related to the CO2 concentration in the inclusion according to the relation: Mole% CO2 ¼ e−3:959 IR2 þ8:0734 IR where ICO2 is the intensity of the 1388 cm−1 peak and IH2O is the intensity of the 3600 cm−1 peak. The relationship between linear peak intensity and composition was established at 350 °C for compositions ranging from 2.5 to 50 mol% CO2. The CO2–H2O linear peak intensity ratio ( IR) varies with temperature and the relationship between composition and IR is strictly valid only if the inclusions are analyzed at 350 °C. The peak area ratio is defined as AR=ACO2/(ACO2+AH2O), where ACO2 is the integrated area under the 1388 cm−1 peak and AH2O is the integrated area under the 3600 cm−1 peak. The relationship between peak area ratio (AR) and the CO2 concentration in the inclusions is given as: Mole% CO2 ¼ 312:5 AR The equation relating peak area ratio and composition is valid up to 25 mol% CO2 and from 300 to 450 °C. The relationship between linear peak intensity ratio and composition should be used for inclusions containing ≤50 mol% CO2 and which can be analyzed at 350 °C. The relationship between composition and peak area ratios should be used when analyzing inclusions at temperatures less than or greater than 350 °C (300–450) but can only be used for compositions ≤25 mol% CO2. Note that this latter relationship has a somewhat larger standard deviation compared to the intensity ratio relationship. Calibration relationships employing peak areas for both members of the Fermi diad (ν1 at 1285 cm−1 and 2ν2 at 1388 cm−1) were slightly poorer than those using only the 2ν2 (1388 cm−1) member owing to interference from quartz peak at approximately 1160 cm−1

Partitioning behavior of trace elements between dacitic melt and plagioclase, orthopyroxene, and clinopyroxene based on laser ablation ICPMS analysis of silicate melt inclusions

Partitioning behavior of Sc, Ti, V, Mn, Sr, Y, Zr, Nb, Ba, La, Nd, Sm, Eu, Gd, Dy, Ho, Yb, Hf, and Pb between dacitic silicate melt and clinopyroxene, orthopyroxene, and plagioclase has been determined based on laser ablation-inductively coupled plasma mass spectrometric (LA-ICPMS) analysis of melt inclusions and the immediately adjacent host mineral. Samples from the 1988 eruption of White Island, New Zealand were selected because petrographic evidence suggests that all three mineral phases are in equilibrium with each other and with the melt inclusions. All three phenocryst types are found as mineral inclusions within each of the other phases, and mineral inclusions often coexist with melt inclusions in growth-zone assemblages. Compositions of melt inclusions do not vary between the different host minerals, suggesting that boundary layer processes did not affect compositions of melt inclusions and that post-trapping modifications have not occurred. Partition coefficients were calculated from the host and melt inclusion compositions and results were compared to published values. All trace elements examined in this study except Sr are incompatible in plagioclase, and all measured trace elements except for Mn are incompatible in orthopyroxene. In clinopyroxene, Sc, V, and Mn are compatible, and Y, Ti, HREE, and the MREE are only slightly incompatible. Most partition coefficients overlap the wide range of values reported in the literature, but the White Island data are consistently at the lower end of the range in published values. Results from the literature obtained using modern microanalytical techniques such as secondary ion mass spectrometry (SIMS) or proton induced X-ray emission spectroscopy (PIXE) also fall at the lower end of the published values, whereas partition coefficients determined from bulk analysis of glass and crystals separated from volcanic rocks typically extend to higher values. Rapid crystal growth-rates, crystal zonation, or the presence of accessory mineral inclusions in phenocrysts likely accounts for the wide range and generally higher partition coefficients obtained using bulk sampling techniques. The results for 3+ cations from this study are consistent with theoretical predictions based on a lattice strain model for site occupancy. The results also confirm that the melt inclusion-mineral (MIM) technique is a reliable method for determining partition coefficients, as long as the melt inclusions have not experienced post-entrapment reequilibration