2,134 research outputs found
Do Winds Control the Confluence of Subtropical and Subantarctic Surface Waters East of New Zealand?
The confluence region east of New Zealand is one of only a few places in the
world where the Antarctic Circumpolar Current meets the strong southwardflowing
boundary current of a subtropical gyre. The convergence of subtropical
and subantarctic water creates strong fronts. The fronts have clear signatures
in height and temperature that make them appropriate places to investigate
ocean/climate variability. The location and extent of the New Zealand confluence
should respond to changes in large-scale wind patterns, as changes in
South Pacific currents have been linked to wind shifts. However, recent studies
have shown that highly energetic eddies, local winds, and the bathymetry may
be significant controls of currents and associated fronts. This thesis investigates
the temporal and spatial variability of the confluence and evaluates its response
to variability in South Pacific winds.
Analysis of the 18-year time series, from January 1993 to December 2010, of
sea surface height mapped from satellite altimetry was used to investigate the
location and extent of fronts and the eddy activity and relate these to the wind
forcing. Wind stress data were used with the Island Rule to estimate the winddriven
transport of the western boundary currents that feed the confluence. In
addition, the climate modes Southern Annular Mode (SAM) and Southern Oscillation
Index (SOI) were used to examine the influence of the principal modes
of atmospheric variability. Time series of the local wind stress curl and local
climate indices were calculated and compared to the intensity of the confluence
to test any influence of local forcing. In addition, bathymetric effects were investigated
by evaluating evidence for preferred front locations near topographic
features.
Sea level anomalies in the confluence region are increasing at 3.4 cm decadeā»Ā¹.
The sea surface height gradients and the eddy kinetic energy are also increasing
at a rate of 0.01 cm kmā»Ā¹ and 23 cmĀ² sā»Ā² per decade respectively, indicating
an intensification of the fronts and eddy activity in the confluence. There is a
high and significant correlation (r = 0.84) between the front and eddy signals
reflecting baroclinic instabilities inherent in the fronts. Difference in transport
anomalies across the confluence derived from the Island Rule are also increasing
at 8.8 Sv decadeā»Ā¹. SAM and SOI indices showed little or no correspondence
with variability in the confluence intensity and eddy kinetic energy, and the
same lack of correspondence was observed in local winds and local indices.
While these results suggest a connection between the variability in the confluence
and South Pacific winds, there is a preferential location of the strongest
fronts and eddy activity northeast of Bounty Plateau and Bollons Seamount,
indicating some bathymetric control.
The correspondence between basin-scale winds and sea surface height gradients
in the confluence region indicates that if wind stress continues to increase,
as current trends predict, front intensity and eddy activity will also increase,
enhancing the transfer of heat and nutrients that, respectively, influence energy
transfer and biological productivity
Industry Career Guide: IT-BPO
Off-shoring describes the relocation by a company of its business processes like manufacturing, operations, and support processes to other countries, particularly in global production networks. Outsourcing involves the contracting of a third party to perform the necessary processes within the company. The recent development of the ability of companies to outsource suppliers outside the nation gave rise to the concept of off-shoring which not only implies foreign inputs to work domestically, but involves cross-country collaborations as well. The Off-shoring and Outsourcing (O&O) Industry is known widely as the IT-BPO (Information Technology ā Business Process Outsourcing) industry. The industry is relatively new, but the dynamism it exhibits is great. Global O&O has grown to 15% in 2008, which is the third largest around the world. In 2008, the industry contributes 3.6% of Philippine GDP and 12.36% of exports which is particular in the export of services
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Intrauterine programming of obesity and type 2 diabetes
Abstract: The type 2 diabetes epidemic and one of its predisposing factors, obesity, are major influences on global health and economic burden. It is accepted that genetics and the current environment contribute to this epidemic; however, in the last two decades, both human and animal studies have consolidated considerable evidence supporting the ādevelopmental programmingā of these conditions, specifically by the intrauterine environment. Here, we review the various in utero exposures that are linked to offspring obesity and diabetes in later life, including epidemiological insights gained from natural historical events, such as the Dutch Hunger Winter, the Chinese famine and the more recent Quebec Ice Storm. We also describe the effects of gestational exposure to endocrine disruptors, maternal infection and smoking to the fetus in relation to metabolic programming. Causal evidence from animal studies, motivated by human observations, is also discussed, as well as some of the proposed underlying molecular mechanisms for developmental programming of obesity and type 2 diabetes, including epigenetics (e.g. DNA methylation and histone modifications) and microRNA interactions. Finally, we examine the effects of non-pharmacological interventions, such as improving maternal dietary habits and/or increasing physical activity, on the offspring epigenome and metabolic outcomes
Lipid Metabolism Is Dysregulated before, during and after Pregnancy in a Mouse Model of Gestational Diabetes.
The aim of the current study was to test the hypothesis that maternal lipid metabolism was modulated during normal pregnancy and that these modulations are altered in gestational diabetes mellitus (GDM). We tested this hypothesis using an established mouse model of diet-induced obesity with pregnancy-associated loss of glucose tolerance and a novel lipid analysis tool, Lipid Traffic Analysis, that uses the temporal distribution of lipids to identify differences in the control of lipid metabolism through a time course. Our results suggest that the start of pregnancy is associated with several changes in lipid metabolism, including fewer variables associated with de novo lipogenesis and fewer PUFA-containing lipids in the circulation. Several of the changes in lipid metabolism in healthy pregnancies were less apparent or occurred later in dams who developed GDM. Some changes in maternal lipid metabolism in the obese-GDM group were so late as to only occur as the control dams' systems began to switch back towards the non-pregnant state. These results demonstrate that lipid metabolism is modulated in healthy pregnancy and the timing of these changes is altered in GDM pregnancies. These findings raise important questions about how lipid metabolism contributes to changes in metabolism during healthy pregnancies. Furthermore, as alterations in the lipidome are present before the loss of glucose tolerance, they could contribute to the development of GDM mechanistically
Cell-autonomous programming of rat adipose tissue insulin signalling proteins by maternal nutrition.
AIMS/HYPOTHESIS: Individuals with a low birthweight have an increased risk of developing type 2 diabetes mellitus in adulthood. This is associated with peripheral insulin resistance. Here, we aimed to determine whether changes in insulin signalling proteins in white adipose tissue (WAT) can be detected prior to the onset of impaired glucose tolerance, determine whether these changes are cell-autonomous and identify the underlying mechanisms involved. METHODS: Fourteen-month-old male rat offspring born to dams fed a standard protein (20%) diet or a low (8%) protein diet throughout gestation and lactation were studied. Fat distribution and adipocyte size were determined. Protein content and mRNA expression of key insulin signalling molecules were analysed in epididymal WAT and in pre-adipocytes that had undergone in vitro differentiation. RESULTS: The offspring of low protein fed dams (LP offspring) had reduced visceral WAT mass, altered fat distribution and a higher percentage of small adipocytes in epididymal WAT. This was associated with reduced levels of IRS1, PI3K p110Ī², Akt1 and PKCĪ¶ proteins and of phospho-Akt Ser473. Corresponding mRNA transcript levels were unchanged. Similarly, in vitro differentiated adipocytes from LP offspring showed reduced protein levels of IRĪ², IRS1, PI3K p85Ī± and p110Ī² subunits, and Akt1. Levels of Akt Ser473 and IRS1 Tyr612 phosphorylation were reduced, while IRS1 Ser307 phosphorylation was increased. CONCLUSIONS/INTERPRETATION: Maternal protein restriction during gestation and lactation changes the distribution and morphology of WAT and reduces the levels of key insulin signalling proteins in the male offspring. This phenotype is retained in in vitro differentiated adipocytes, suggesting that programming occurs via cell-autonomous mechanism(s).This work was supported by Diabetes UK (MSM-G; no. 12/0004508), the British Heart Foundation (SEO; no. FS/09/029/27902) and the UK Medical Research Council (SEO; no. MC_UU_12012/4)This is the accepted manuscript. It is currently embargoed pending publication
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Exploring Telomere Dynamics in Aging Male Rat Tissues: Can Tissue-Specific Differences Contribute to Age-Associated Pathologies?
INTRODUCTION: Due to increasing lifespan, global aging rates are rising rapidly and age-associated diseases are increasing. To ensure that health span is concomitant with life span, a greater understanding of cellular mechanisms of aging is important. METHODS: Telomere length analysis from a wide range of tissues from weaning, young adult, and middle-aged (3, 12 and 52 week) male Wistar rats were conducted using Southern blotting. Telomere lengths were compared between tissues and ages using regression models based on the ratios of longest-to-shortest telomere fragments. RESULTS: Robust linear age-dependent telomere attrition was observed in the liver; 3 versus 12 weeks, 3 versus 52 weeks (p < 0.01), 12 versus 52 weeks (p < 0.05) and the heart; 3 versus 12 weeks (p < 0.05) and 3 versus 52 weeks (p < 0.001). More subtle shortening was observed in aorta and epididymal fat; 3 and 12 versus 52 weeks (p < 0.001) and in skeletal muscle; 3 versus 52 weeks (p < 0.05), 12 versus 52 weeks (p < 0.01). Young thymus telomeres increased in length (3 vs. 12 weeks) and then shortened between 12 and 52 weeks (p < 0.001). We also reported disparity in telomere shortening within tissues: telomeres in aging brain cortex significantly shortened; 3 versus 52 weeks (p < 0.05), 12 versus 52 weeks (p < 0.01). This was not seen in the hypothalamic region. A robust stepwise shortening was observed in the renal cortex; 3 versus 12 weeks, 12 versus 52 weeks (p < 0.05), and 3 versus 52 weeks (p < 0.001), which was not as apparent in the renal medulla; 3 versus 12 weeks (p < 0.01) and 3 versus 52 weeks (p < 0.01). The vastus lateralis skeletal muscle demonstrated the shortest telomere length at weaning and underwent robust age-associated attrition; 3 versus 52 weeks (p < 0.05), 12 versus 52 weeks (p < 0.01). We demonstrated that specific tissues exhibit unique telomere attrition profiles which may partially explain why certain diseases are more prevalent in aged individuals. DISCUSSION/CONCLUSION: We show wide variations between tissues in vulnerability to the aging process. In the future, this may help target potential interventions to improve health span
A mouse model of gestational diabetes shows dysregulated lipid metabolism post-weaning, after return to euglycaemia.
BACKGROUND: Gestational diabetes is associated with increased risk of type 2 diabetes mellitus and cardiovascular disease for the mother in the decade after delivery. However, the molecular mechanisms that drive these effects are unknown. Recent studies in humans have shown that lipid metabolism is dysregulated before diagnosis of and during gestational diabetes and we have shown previously that lipid metabolism is also altered in obese female mice before, during and after pregnancy. These observations led us to the hypothesis that this persistent dysregulation reflects an altered control of lipid distribution throughout the organism. METHODS: We tested this in post-weaning (PW) dams using our established mouse model of obese GDM (high fat, high sugar, obesogenic diet) and an updated purpose-built computational tool for plotting the distribution of lipid variables throughout the maternal system (Lipid Traffic Analysis v2.3). RESULTS: This network analysis showed that unlike hyperglycaemia, lipid distribution and traffic do not return to normal after pregnancy in obese mouse dams. A greater range of phosphatidylcholines was found throughout the lean compared to obese post-weaning dams. A range of triglycerides that were found in the hearts of lean post-weaning dams were only found in the livers of obese post-weaning dams and the abundance of odd-chain FA-containing lipids differed locally in the two groups. We have therefore shown that the control of lipid distribution changed for several metabolic pathways, with evidence for changes to the regulation of phospholipid biosynthesis and FA distribution, in a number of tissues. CONCLUSIONS: We conclude that the control of lipid metabolism is altered following an obese pregnancy. These results support the hypothesis that obese dams that developed GDM maintain dysregulated lipid metabolism after pregnancy even when glycaemia returned to normal, and that these alterations could contribute to the increased risk of later type 2 diabetes and cardiovascular disease
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