Effects of Administration of Estradiol-17P on the Serum and Anterior Pituitary IGF System in Pigs

The anterior pituitary (AP) gland functions as a storage and releasing unit for several hormones; growth hormone (GH), gonadotrophins (luteinizing hormone and follicle stimulating hormone), prolactin, adrenocorticotropin hormone, and tyroid stimulating hormone. Luteinizing hormone (LH) functions to increase ovarian follicular growth and maturation and responds to increasing concentrations of estradiol-17β (E2) that occur at estrus to cause ovulation. Production and secretion of the protein, insulin-like grwoth factor-I (IGF-I), occurs primarily in the liver, in response to GH release from the anterior pituitary gland. Insulin-like growth factor-I increases glucose uptake, amino acid transport, and glycogen synthesis resulting in increased protein accretion Mitogenic effects of IGF-I can be manifested by increases in DNA, RNA, and protein. Furthermore, IGF-I stimulates differentiation at low levels usually preceding a mitogenic response. The biological effects of IGF-I are mediated by its interaction with the IGF type 1 receptor and modulated by IGF binding proteins (IGFBPs). Insulin-like grwoth factor-I, IGFBPs, and IGF receptors have been detected in the AP gland of several species and may exert regulatory effects at the hypthalmaic-hypophyseal level affecting gonadotrophins, and in turn, reproductive performance

Serum Concentrations of IGF-1 and Steroids in Growing Boars, Barrows and Gilts.

It is known that boars, barrows, and gilts grow at different rates and with varying defficiencies. Gilts generally eat less, grow slower, but are more efficient and have leaner carcasses than. One way in which growth may be regulated in pigs is through changes in circulating IGF-I and (or) IGF binding proteins (IGFBPs) Insulin-like growth factors-I has been shown to stimulate amino acid and lgucose uptake and increase protein synthesis, while IGFBPs can function to inhibit or protentiate the actions of IGFs. Estradiol has been demonstrated to regulate expression of the IGF system. Administration of estradiol increased serum concentrations of IGF-I and relative amounts of IGFBP-3 and -4 in the ewe. Boars produce more estradiol than gilts or barrows and also exhibit greater serum concentrations of IGF-1 and IGFB-3. Boars produce more testosterone than gilts or barrows, which may work in concert with stradiol to increase circulating levels of IGF-1 and IGFBP-3 similar to what is observed in implanted steers. The objectives of the current experiment were to determine 1) if serum concentrations of IGF-1, estradiol-17β, testosterone, and relative amounts of IGFBPs differ in growing boars, barrows, and gilts, and 2) if growht rate and cirulating levels of IGF-1 and relative amounts of serum IGFBPs were related to serum concentrations of estradiol and testosterone

The Origin, Early Evolution and Predictability of Solar Eruptions

Coronal mass ejections (CMEs) were discovered in the early 1970s when space-borne coronagraphs revealed that eruptions of plasma are ejected from the Sun. Today, it is known that the Sun produces eruptive flares, filament eruptions, coronal mass ejections and failed eruptions; all thought to be due to a release of energy stored in the coronal magnetic field during its drastic reconfiguration. This review discusses the observations and physical mechanisms behind this eruptive activity, with a view to making an assessment of the current capability of forecasting these events for space weather risk and impact mitigation. Whilst a wealth of observations exist, and detailed models have been developed, there still exists a need to draw these approaches together. In particular more realistic models are encouraged in order to asses the full range of complexity of the solar atmosphere and the criteria for which an eruption is formed. From the observational side, a more detailed understanding of the role of photospheric flows and reconnection is needed in order to identify the evolutionary path that ultimately means a magnetic structure will erupt

Mum or bub? Which influences breastfeeding loyalty

The need for social marketing research in the area of breastfeeding is highlighted by the failure of campaigns to increase breastfeeding rates over the past two decades in developed countries. This is despite evidence of the health benefits of longer breastfeeding duration to both baby and mother, and the high levels of expenditure on these campaigns. Whilst past campaign approaches typically focus on baby-oriented factors, breastfeeding is a complex behaviour that for many women involves barriers that influence their commitment to continued breastfeeding. Using social marketing, this research investigates the role of mother-centred factors on loyalty to breastfeeding. A sample of 405 Australian women completed an online survey. The data were analysed using structural equation modelling, which revealed that mother-oriented, rather than baby-oriented, factors influence attitudinal and behavioural loyalty to breastfeeding