168 research outputs found
Chemical weathering and provenance evolution of Holocene–Recent sediments from the Western Indus Shelf, Northern Arabian Sea inferred from physical and mineralogical properties
We present a multi-proxy mineral record based on X-ray diffraction and diffuse reflectance spectrophotometry analysis for two cores from the western Indus Shelf in order to reconstruct changing weathering intensities, sediment transport, and provenance variations since 13 ka. Core Indus-10 is located northwest of the Indus Canyon and exhibits fluctuations in smectite/(illite + chlorite) ratios that correlate with monsoon intensity. Higher smectite/(illite + chlorite) and lower illite crystallinity, normally associated with stronger weathering, peaked during the Early–Mid Holocene, the period of maximum summer monsoon. Hematite/goethite and magnetic susceptibility do not show clear co-variation, although they both increase at Indus-10 after 10 ka, as the monsoon weakened. At Indus-23, located on a clinoform just west of the canyon, hematite/goethite increased during a period of monsoon strengthening from 10 to 8 ka, consistent with increased seasonality and/or reworking of sediment deposited prior to or during the glacial maximum. After 2 ka terrigenous sediment accumulation rates in both cores increased together with redness and hematite/goethite, which we attribute to widespread cultivation of the floodplain triggering reworking, especially after 200 years ago. Over Holocene timescales sediment composition and mineralogy in two localities on the high-energy shelf were controlled by varying degrees of reworking, as well as climatically modulated chemical weathering
Glucocorticoid Regulation of SLIT/ROBO Tumour Suppressor Genes in the Ovarian Surface Epithelium and Ovarian Cancer Cells
The three SLIT ligands and their four ROBO receptors have fundamental roles in mammalian development by promoting apoptosis and repulsing aberrant cell migration. SLITs and ROBOs have emerged as candidate tumour suppressor genes whose expression is inhibited in a variety of epithelial tumours. We demonstrated that their expression could be negatively regulated by cortisol in normal ovarian luteal cells. We hypothesised that after ovulation the locally produced cortisol would inhibit SLIT/ROBO expression in the ovarian surface epithelium (OSE) to facilitate its repair and that this regulatory pathway was still present, and could be manipulated, in ovarian epithelial cancer cells. Here we examined the expression and regulation of the SLIT/ROBO pathway in OSE, ovarian cancer epithelial cells and ovarian tumour cell lines. Basal SLIT2, SLIT3, ROBO1, ROBO2 and ROBO4 expression was lower in primary cultures of ovarian cancer epithelial cells when compared to normal OSE (P<0.05) and in poorly differentiated SKOV-3 cells compared to the more differentiated PEO-14 cells (P<0.05). Cortisol reduced the expression of certain SLITs and ROBOs in normal OSE and PEO-14 cells (P<0.05). Furthermore blocking SLIT/ROBO activity reduced apoptosis in both PEO-14 and SKOV-3 tumour cells (P<0.05). Interestingly SLIT/ROBO expression could be increased by reducing the expression of the glucocorticoid receptor using siRNA (P<0.05). Overall our findings indicate that in the post-ovulatory phase one role of cortisol may be to temporarily inhibit SLIT/ROBO expression to facilitate regeneration of the OSE. Therefore this pathway may be a target to develop strategies to manipulate the SLIT/ROBO system in ovarian cancer
Prenatal Programming of Metabolic Syndrome in the Common Marmoset Is Associated With Increased Expression of 11β-Hydroxysteroid Dehydrogenase Type 1
OBJECTIVE: Recent studies in humans and animal models of obesity have shown increased adipose tissue activity of 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1), which amplifies local tissue glucocorticoid concentrations. The reasons for this 11beta-HSD1 dysregulation are unknown. Here, we tested whether 11beta-HSD1 expression, like the metabolic syndrome, is "programmed" by prenatal environmental events in a nonhuman primate model, the common marmoset monkey. RESEARCH DESIGN AND METHODS: We used a "fetal programming" paradigm where brief antenatal exposure to glucocorticoids leads to the metabolic syndrome in the offspring. Pregnant marmosets were given the synthetic glucocorticoid dexamethasone orally for 1 week in either early or late gestation, or they were given vehicle. Tissue 11beta-HSD1 and glucocorticoid receptor mRNA expression were examined in the offspring at 4 and 24 months of age. RESULTS: Prenatal dexamethasone administration, selectively during late gestation, resulted in early and persistent elevations in 11beta-HSD1 mRNA expression and activity in the liver, pancreas, and subcutaneous-but not visceral-fat. The increase in 11beta-HSD1 occurred before animals developed obesity or overt features of the metabolic syndrome. In contrast to rodents, in utero dexamethasone exposure did not alter glucocorticoid receptor expression in metabolic tissues in marmosets. CONCLUSIONS: These data suggest that long-term upregulation of 11beta-HSD1 in metabolically active tissues may follow prenatal "stress" hormone exposure and indicates a novel mechanism for fetal origins of adult obesity and the metabolic syndrome
Chromium Remediation or Release? Effect of Iron(II) Sulfate Addition on Chromium(VI) Leaching from Columns of Chromite Ore Processing Residue
Chromite ore processing residue (COPR), derived from the
so-called high lime processing of chromite ore, contains
high levels of Cr(III) and Cr(VI) and has a pH between 11 and
12. Ferrous sulfate, which is used for remediation of
Cr(VI) contamination in wastewater and soils via reduction
to Cr(III) and subsequent precipitation of iron(III)/chromium-
(III) hydroxide, has also been proposed for remediation
of Cr(VI) in COPR. Instead, however, addition of FeSO4 to
the infiltrating solution in column experiments with COPR
greatly increased leaching of Cr(VI). Leached Cr(VI) increased
from 3.8 to 12.3 mmol kg-1 COPR in 25 pore volumes
with 20 mM FeSO4, reaching solution concentrations as
high as 1.6 mM. Fe(II) was ineffective in reducing Cr(VI) to
Cr(III) because it precipitated when it entered the column
due to the high pH of COPR, while Cr(VI) in solution
was transported away with the infiltrating solution. The
large increase in leaching of Cr(VI) upon infiltration of sulfate,
either as FeSO4 or Na2SO4, was caused by anion exchange
of sulfate for chromate in the layered double hydroxide
mineral hydrocalumite, a process for which scanning electron
microscopy with energy-dispersive X-ray microanalysis
provided direct evidence
Using Quantitative Spectroscopic Analysis to Determine the Properties and Distances of Type II-Plateau Supernovae: SNe 2005cs and 2006bp
We analyze the Type II Plateau supernovae (SN II-P) 2005cs and 2006bp with
the non-LTE model atmosphere code CMFGEN. We fit 13 spectra in the first month
for SN 2005cs and 18 for SN 2006bp. {\sl Swift} ultraviolet photometry and
ground-based optical photometry calibrate each spectrum. Our analysis shows
both objects were discovered less than 3 days after they exploded, making these
the earliest SN II-P spectra ever studied. They reveal broad and very weak
lines from highly-ionized fast ejecta with an extremely steep density profile.
We identify He{\sc ii} 4686\AA emission in the SN 2006bp ejecta. Days later,
the spectra resemble the prototypical Type II-P SN 1999em, which had a
supergiant-like photospheric composition. Despite the association of SN 2005cs
with possible X-ray emission, the emergent UV and optical light comes from the
photosphere, not from circumstellar emission.
We surmise that the very steep density fall-off we infer at early times may
be a fossil of the combined actions of the shock wave passage and radiation
driving at shock breakout. Based on tailored CMFGEN models, the direct-fitting
technique and the Expanding Photosphere Method both yield distances and
explosion times that agree within a few percent. We derive a distance to NGC
5194, the host of SN 2005cs, of 8.90.5 Mpc and 17.50.8 Mpc for SN
2006bp in NGC 3953. The luminosity of SN 2006bp is 1.5 times that of SN 1999em,
and 6 times that of SN 2005cs. Reliable distances to Type II-P supernovae that
do not depend on a small range in luminosity provide an independent route to
the Hubble Constant and improved constraints on other cosmological parameters.Comment: 27 pages, 16 figures, 11 tables, accepted to ApJ, high-resolution of
the paper available at
http://hermes.as.arizona.edu/~luc/snIIP/sn05cs_06bp.ps.g
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The anti-epileptic drug Valproic Acid (VPA) inhibits steroidogenesis in bovine theca and granulosa cells in vitro
Valproic acid (VPA) is used widely to treat epilepsy and bipolar disorder. Women undergoing VPA treatment reportedly have an increased incidence of polycystic ovarian syndrome (PCOS)-like symptoms including hyperandrogenism and oligo- or amenorrhoea. To investigate potential direct effects of VPA on ovarian steroidogenesis we used primary bovine theca (TC) and granulosa (GC) cells maintained under conditions that preserve their 'follicular' phenotype. Effects of VPA (7.8-500 µg/ml) on TC were tested with/without LH. Effects of VPA on GC were tested with/without FSH or IGF analogue. VPA reduced (P99% decrease; P<0.0001) with lesser effects on LHR, STAR, CYP11A1 and HSD3B1 mRNA (<90% decrease; P<0.05). VPA only reduced TC progesterone secretion induced by the highest (luteinizing) LH dose tested; TC number was unaffected by VPA. At higher concentrations (125-500 µg/ml) VPA inhibited basal, FSH- and IGF-stimulated estradiol secretion (P<0.0001) by GC without affecting progesterone secretion or cell number. VPA reversed FSH-induced upregulation of CYP19A1 and HSD17B1 mRNA abundance (P<0.001). The potent histone deacetylase (HDAC) inhibitors trichostatin A and scriptaid also suppressed TC androstenedione secretion and granulosal cell oestrogen secretion suggesting that the action of VPA reflects its HDAC inhibitory properties. In conclusion, these findings refute the hypothesis that VPA has a direct stimulatory action on TC androgen output. On the contrary, VPA inhibits both LH-dependent androgen production and FSH/IGF-dependent estradiol production in this in vitro bovine model, likely by inhibition of HDAC
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