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G G Scatigno - One of the best experts on this subject based on the ideXlab platform.
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the effect of Salt Loading on chloride induced stress corrosion cracking of 304l austenitic stainless steel under atmospheric conditions
Materialia, 2019Co-Authors: G G Scatigno, P Dong, Mary P Ryan, M R WenmanAbstract:Abstract The effect of Salt Loading on chloride-induced stress corrosion cracking in 304 L was studied at atmospheric pressure. Stress relieved samples were uniaxially pre-strained to 5% and were loaded with nine levels of MgCl2, investigating Cl− deposition levels from 1.7 × 10−4 to 3.1 x 10−2 g cm−2. Samples were subject to 60 MPa stress, 90 °C at 70% relative humidity, for 480 h. A direct correlation between chloride deposition and the density of cracking and corrosion was observed between 5.7 × 10−4 and 1.96 × 10−2 g cm−2. Crack propagation rates were constant between Salt Loadings of 5.7 × 10−4 and 2.4 × 10−2 g cm−2 at 1–2 µm h−1.
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the effect of Salt Loading on chloride induced stress corrosion cracking of 304l austenitic stainless steel under atmospheric conditions
Social Science Research Network, 2019Co-Authors: G G Scatigno, P Dong, Mary P Ryan, M R WenmanAbstract:The effect of Salt Loading on chloride-induced stress corrosion cracking in 304L was studied at atmospheric pressure. Stress relieved samples were uniaxially pre-strained to 5% and were loaded with nine levels of MgCl2 from 2.3 x 10-4 to 4.2 x 10-2 g.cm-2. Samples were subject to 60 MPa stress, 90°C at 70% relative humidity, for 480 hours. A direct correlation between Salt Loading and the density of cracking and corrosion was observed between 7.6 x 10-4 and 2.6 x 10-2 g.cm-2 . Crack propagation rates were constant between Salt Loadings of 7.6 x 10-4 and 3.2 x 10-2 g.cm-2 at 1-2 µm.hr-1.
David Murphy - One of the best experts on this subject based on the ideXlab platform.
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epigenetic control of the vasopressin promoter explains physiological ability to regulate vasopressin transcription in dehydration and Salt Loading states in the rat
Journal of Neuroendocrinology, 2016Co-Authors: Michael P Greenwood, David Murphy, Mingkwan Greenwood, Ben Gillard, Su Yi Loh, Julian F R PatonAbstract:The synthesis of arginine vasopressin (AVP) in the supraoptic nucleus (SON) and paraventricular nucleus (PVN) of the hypothalamus is sensitive to increased plasma osmolality and a decreased blood volume, and thus is robustly increased by both dehydration (increased plasma osmolality and decreased blood volume) and Salt Loading (increased plasma osmolality). Both stimuli result in functional remodelling of the SON and PVN, a process referred to as functional-related plasticity. Such plastic changes in the brain have recently been associated with altered patterns of DNA methylation at CpG (cytosine-phosphate-guanine) residues, a process considered to be important for the regulation of gene transcription. In this regard, the proximal Avp promoter contains a number of CpG sites and is recognised as one of four CpG islands for the Avp gene, suggesting that methylation may be regulating Avp transcription. In the present study, we show that, in an immortalised hypothalamic cell line 4B, the proximal Avp promoter is highly methylated, and treatment of these cells with the DNA methyltransferase inhibitor 5-Aza-2'-deoxycytidine to demethylate DNA dramatically increases basal and stimulated Avp biosynthesis. We report no changes in the expression of DNA methyltransferases, Dnmt1 and Dnmt3a, whereas there is decreased expression of the demethylating enzyme ten-eleven-translocation 2, Tet2, in the SON by dehydration and Salt Loading. We found higher methylation of the SON Avp promoter in dehydrated but not Salt-loaded rats. By analysis of individual CpG sites, we observed hypomethylation, hypermethylation and no change in methylation of specific CpGs in the SON Avp promoter of the dehydrated rat. Using reporter gene assays, we show that mutation of individual CpGs can result in altered Avp promoter activity. We propose that methylation of the SON Avp promoter is necessary to co-ordinate the duel inputs of increased plasma osmolality and decreased blood volume on Avp transcription in the chronically dehydrated rat.
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a rna seq analysis of the rat supraoptic nucleus transcriptome effects of Salt Loading on gene expression
PLOS ONE, 2015Co-Authors: Kory R Johnson, David Murphy, Charles Hindmarch, Yasmmyn D Salinas, Yijun Shi, Michael P Greenwood, See Ziau Hoe, Harold GainerAbstract:Magnocellular neurons (MCNs) in the hypothalamo-neurohypophysial system (HNS) are highly specialized to release large amounts of arginine vasopressin (Avp) or oxytocin (Oxt) into the blood stream and play critical roles in the regulation of body fluid homeostasis. The MCNs are osmosensory neurons and are excited by exposure to hypertonic solutions and inhibited by hypotonic solutions. The MCNs respond to systemic hypertonic and hypotonic stimulation with large changes in the expression of their Avp and Oxt genes, and microarray studies have shown that these osmotic perturbations also cause large changes in global gene expression in the HNS. In this paper, we examine gene expression in the rat supraoptic nucleus (SON) under normosmotic and chronic Salt-Loading SL) conditions by the first time using “new-generation”, RNA sequencing (RNA-Seq) methods. We reliably detect 9,709 genes as present in the SON by RNA-Seq, and 552 of these genes were changed in expression as a result of chronic SL. These genes reflect diverse functions, and 42 of these are involved in either transcriptional or translational processes. In addition, we compare the SON transcriptomes resolved by RNA-Seq methods with the SON transcriptomes determined by Affymetrix microarray methods in rats under the same osmotic conditions, and find that there are 6,466 genes present in the SON that are represented in both data sets, although 1,040 of the expressed genes were found only in the microarray data, and 2,762 of the expressed genes are selectively found in the RNA-Seq data and not the microarray data. These data provide the research community a comprehensive view of the transcriptome in the SON under normosmotic conditions and the changes in specific gene expression evoked by Salt Loading.
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exaggerated response of arginine vasopressin enhanced green fluorescent protein fusion gene to Salt Loading without disturbance of body fluid homeostasis in rats
Journal of Neuroendocrinology, 2006Co-Authors: Tomoki Fujio, Hiroaki Fujihara, Tatsushi Onaka, Mitsuhiro Kawata, M Shibata, S Yamada, Kentarou Tanaka, H Morita, Govindan Dayanithi, David MurphyAbstract:We examined the effects of chronic Salt Loading on the hypothalamic expressions of the enhanced green fluorescent protein (eGFP), arginine vasopressin (AVP) and oxytocin (OXT) genes in AVP-eGFP transgenic rats that expressed eGFP in the hypothalamic AVP-containing neurones. In these rats, Salt Loading for 5 days caused a marked increase of the eGFP fluorescence in the magnocellular divisions of the paraventricular nucleus (PVN), the supraoptic nucleus (SON) and the internal layer of the median eminence. Expression of the eGFP gene was increased seven- to eight-fold in the PVN and SON of Salt-loaded rats in comparison with euhydrated rats. By contrast, none of these changes were observed in the suprachiasmatic nucleus. The expression of the AVP and OXT genes was increased 1.5- to two-fold in the PVN and SON of Salt-loaded nontransgenic (control) and transgenic rats. There were no differences in the expression levels of the AVP and OXT genes in the PVN and SON between nontransgenic (control) and transgenic animals under normal conditions and after Salt Loading. In the posterior pituitary gland, the intensity of the eGFP fluorescence did not change after Salt Loading for 5 days, but increased after 10 days of Salt Loading. Upon Salt Loading, significant increases in the plasma AVP concentrations, plasma osmolality and plasma Na+ were observed. Furthermore, there were no significant differences in changes of water intake, food intake, urine volume, urine osmolality, urine Na+ concentrations, and the body weights in both models under normal or Salt-loaded conditions. Our results show that the response of the AVP-eGFP fusion gene to chronic Salt Loading is exaggerated, and humoral responses such as AVP and OXT and the body fluid homeostasis are maintained in AVP-eGFP transgenic rats. The AVP-eGFP transgenic rat gives us a new opportunity to study the dynamics of the AVP system in vivo.
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osmotic stimuli attenuate vasoactive intestinal peptide gene expression in the rat anterior pituitary gland
Molecular and Cellular Endocrinology, 1993Co-Authors: Lijin Chew, David Murphy, Karen Pardy, David A CarterAbstract:Abstract Studies on vasoactive intestinal peptide (VIP) in the anterior pituitary gland have shown that it is synthesized locally, physiologically regulated, and may act as a paracrine/autocrine factor. We have now investigated the regulation of anterior pituitary VIP gene expression in rats during osmotic stimulation. Both Salt-Loading and dehydration resulted in a progressive and marked reduction in VIP mRNA levels as determined by Northern analysis, to 10% of control levels at 14 days of Salt-Loading. The 1.7 and 1.0 kb VIP RNA transcripts were equally affected. Since anterior pituitary VIP is partially localized in lactotrophs we also measured prolactin (PRL) mRNA levels. In contrast to VIP, PRL mRNA levels were increased during both osmotic paradigms, the mRNA levels being significantly raised after 5 days of Salt-Loading to 130% of controls. Further experiments, conducted to examine the mechanism by which VIP gene expression is down-regulated during osmotic stimulation, demonstrated that dopamine and angiotensin II do not appear to be involved. The results show dissociated regulation of VIP and PRL during osmotic stimulation and provide suggestive evidence of a role for anterior pituitary VIP in the animal's osmoregulatory responses. VIP may therefore be a paracrine factor with diverse functional roles.
M R Wenman - One of the best experts on this subject based on the ideXlab platform.
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the effect of Salt Loading on chloride induced stress corrosion cracking of 304l austenitic stainless steel under atmospheric conditions
Materialia, 2019Co-Authors: G G Scatigno, P Dong, Mary P Ryan, M R WenmanAbstract:Abstract The effect of Salt Loading on chloride-induced stress corrosion cracking in 304 L was studied at atmospheric pressure. Stress relieved samples were uniaxially pre-strained to 5% and were loaded with nine levels of MgCl2, investigating Cl− deposition levels from 1.7 × 10−4 to 3.1 x 10−2 g cm−2. Samples were subject to 60 MPa stress, 90 °C at 70% relative humidity, for 480 h. A direct correlation between chloride deposition and the density of cracking and corrosion was observed between 5.7 × 10−4 and 1.96 × 10−2 g cm−2. Crack propagation rates were constant between Salt Loadings of 5.7 × 10−4 and 2.4 × 10−2 g cm−2 at 1–2 µm h−1.
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the effect of Salt Loading on chloride induced stress corrosion cracking of 304l austenitic stainless steel under atmospheric conditions
Social Science Research Network, 2019Co-Authors: G G Scatigno, P Dong, Mary P Ryan, M R WenmanAbstract:The effect of Salt Loading on chloride-induced stress corrosion cracking in 304L was studied at atmospheric pressure. Stress relieved samples were uniaxially pre-strained to 5% and were loaded with nine levels of MgCl2 from 2.3 x 10-4 to 4.2 x 10-2 g.cm-2. Samples were subject to 60 MPa stress, 90°C at 70% relative humidity, for 480 hours. A direct correlation between Salt Loading and the density of cracking and corrosion was observed between 7.6 x 10-4 and 2.6 x 10-2 g.cm-2 . Crack propagation rates were constant between Salt Loadings of 7.6 x 10-4 and 3.2 x 10-2 g.cm-2 at 1-2 µm.hr-1.
Harold Gainer - One of the best experts on this subject based on the ideXlab platform.
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a rna seq analysis of the rat supraoptic nucleus transcriptome effects of Salt Loading on gene expression
PLOS ONE, 2015Co-Authors: Kory R Johnson, David Murphy, Charles Hindmarch, Yasmmyn D Salinas, Yijun Shi, Michael P Greenwood, See Ziau Hoe, Harold GainerAbstract:Magnocellular neurons (MCNs) in the hypothalamo-neurohypophysial system (HNS) are highly specialized to release large amounts of arginine vasopressin (Avp) or oxytocin (Oxt) into the blood stream and play critical roles in the regulation of body fluid homeostasis. The MCNs are osmosensory neurons and are excited by exposure to hypertonic solutions and inhibited by hypotonic solutions. The MCNs respond to systemic hypertonic and hypotonic stimulation with large changes in the expression of their Avp and Oxt genes, and microarray studies have shown that these osmotic perturbations also cause large changes in global gene expression in the HNS. In this paper, we examine gene expression in the rat supraoptic nucleus (SON) under normosmotic and chronic Salt-Loading SL) conditions by the first time using “new-generation”, RNA sequencing (RNA-Seq) methods. We reliably detect 9,709 genes as present in the SON by RNA-Seq, and 552 of these genes were changed in expression as a result of chronic SL. These genes reflect diverse functions, and 42 of these are involved in either transcriptional or translational processes. In addition, we compare the SON transcriptomes resolved by RNA-Seq methods with the SON transcriptomes determined by Affymetrix microarray methods in rats under the same osmotic conditions, and find that there are 6,466 genes present in the SON that are represented in both data sets, although 1,040 of the expressed genes were found only in the microarray data, and 2,762 of the expressed genes are selectively found in the RNA-Seq data and not the microarray data. These data provide the research community a comprehensive view of the transcriptome in the SON under normosmotic conditions and the changes in specific gene expression evoked by Salt Loading.
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a comparison of physiological and transcriptome responses to water deprivation and Salt Loading in the rat supraoptic nucleus
American Journal of Physiology-regulatory Integrative and Comparative Physiology, 2015Co-Authors: Michael P Greenwood, Kory R Johnson, See Ziau Hoe, Julian F R Paton, Andre S Mecawi, Mohd Rais Mustafa, Ghada A Almahmoud, Lucila Leico Kagohara Elias, Jose Antunesrodrigues, Harold GainerAbstract:Salt Loading (SL) and water deprivation (WD) are experimental challenges that are often used to study the osmotic circuitry of the brain. Central to this circuit is the supraoptic nucleus (SON) of the hypothalamus, which is responsible for the biosynthesis of the hormones, arginine vasopressin (AVP) and oxytocin (OXT), and their transport to terminals that reside in the posterior lobe of the pituitary. On osmotic challenge evoked by a change in blood volume or osmolality, the SON undergoes a function-related plasticity that creates an environment that allows for an appropriate hormone response. Here, we have described the impact of SL and WD compared with euhydrated (EU) controls in terms of drinking and eating behavior, body weight, and recorded physiological data including circulating hormone data and plasma and urine osmolality. We have also used microarrays to profile the transcriptome of the SON following SL and remined data from the SON that describes the transcriptome response to WD. From a list of 2,783 commonly regulated transcripts, we selected 20 genes for validation by qPCR. All of the 9 genes that have already been described as expressed or regulated in the SON by osmotic stimuli were confirmed in our models. Of the 11 novel genes, 5 were successfully validated while 6 were false discoveries.
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differential kinetics of oxytocin and vasopressin heteronuclear rna expression in the rat supraoptic nucleus in response to chronic Salt Loading in vivo
Journal of Neuroendocrinology, 2007Co-Authors: Chunmei Yue, Noriko Mutsuga, Yoshihisa Sugimura, Joseph G Verbalis, Harold GainerAbstract:Previous studies have shown that the secretion of oxytocin and vasopressin from the posterior pituitary always accompanies systemic hyperosmotic stimuli in rats, and that oxytocin and vasopressin mRNAs consistently increase in response to prolonged hyperosmotic stimuli. Hence, it has been widely interpreted that oxytocin and vasopressin secretion and gene expression are closely coupled. In the present study, we used both vasopressin and oxytocin intron- specific probes to measure vasopressin and oxytocin heteronuclear RNA (hnRNA) levels, respectively, by in situ hybridisation in the rat supraoptic nucleus (SON) in conjunction with radioimmunoassays of vasopressin and oxytocin peptide levels in plasma and in the posterior pituitary in normally hydrated rats and after 1-5 days of Salt Loading. Increased oxytocin secretion in response to hyperosmotic stimuli exceeded vasopressin secretion at every time point studied. Vasopressin hnRNA in the SON increased to near maximal levels within minutes after the hyperosmotic stimulus, and was maintained throughout all 5 days of Salt Loading. By contrast, oxytocin hnRNA did not significantly change from control levels until approximately 2 days after hyperosmotic stimulation, and was not maximal until 3 days. In summary, increases in oxytocin gene transcription in response to osmotic stimuli are dramatically delayed compared to increases in vasopressin gene transcription under the same conditions. These data indicate that oxytocin gene transcription is not as closely correlated with pituitary peptide secretion as is vasopressin gene transcription, and suggests that there is a fundamental difference in excitation-secretion-transcription coupling mechanisms that regulate these two closely related genes in the rat magnocellular neurones in the SON.
Mary P Ryan - One of the best experts on this subject based on the ideXlab platform.
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the effect of Salt Loading on chloride induced stress corrosion cracking of 304l austenitic stainless steel under atmospheric conditions
Materialia, 2019Co-Authors: G G Scatigno, P Dong, Mary P Ryan, M R WenmanAbstract:Abstract The effect of Salt Loading on chloride-induced stress corrosion cracking in 304 L was studied at atmospheric pressure. Stress relieved samples were uniaxially pre-strained to 5% and were loaded with nine levels of MgCl2, investigating Cl− deposition levels from 1.7 × 10−4 to 3.1 x 10−2 g cm−2. Samples were subject to 60 MPa stress, 90 °C at 70% relative humidity, for 480 h. A direct correlation between chloride deposition and the density of cracking and corrosion was observed between 5.7 × 10−4 and 1.96 × 10−2 g cm−2. Crack propagation rates were constant between Salt Loadings of 5.7 × 10−4 and 2.4 × 10−2 g cm−2 at 1–2 µm h−1.
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the effect of Salt Loading on chloride induced stress corrosion cracking of 304l austenitic stainless steel under atmospheric conditions
Social Science Research Network, 2019Co-Authors: G G Scatigno, P Dong, Mary P Ryan, M R WenmanAbstract:The effect of Salt Loading on chloride-induced stress corrosion cracking in 304L was studied at atmospheric pressure. Stress relieved samples were uniaxially pre-strained to 5% and were loaded with nine levels of MgCl2 from 2.3 x 10-4 to 4.2 x 10-2 g.cm-2. Samples were subject to 60 MPa stress, 90°C at 70% relative humidity, for 480 hours. A direct correlation between Salt Loading and the density of cracking and corrosion was observed between 7.6 x 10-4 and 2.6 x 10-2 g.cm-2 . Crack propagation rates were constant between Salt Loadings of 7.6 x 10-4 and 3.2 x 10-2 g.cm-2 at 1-2 µm.hr-1.
