Twenty-four castrated male lambs initially maintained on a photoperiod of 12 h light:12 h dark were allocated to a factorial experiment with two daylengths (8 h L: 16 h D or 16 h L: 8 h D) and two levels of feeding (restricted or ad libitum). Blood samples were taken every 4 h for 24 h during the introductory period and after 24, 51 and 79 days of treatment. There were highly significant positive effects of daylength and level of feeding on serum prolactin: mean concentrations increased from a mean of 38 plus or minus 1 ng/ml during the introductory period until at day 79 they were: 8L: 16D (restricted diet), 81 ng/ml; (food ad libitum), 167 ng/ml; 16L:8D (restricted diet), 262 ng/ml; (food ad libitum), 262 ng/ml (S.E. of treatment mean plus or minus 4). Long daylength and feeding ad libitum also significantly increased growth rate.
Interconversion of active and inactive glucocorticoids, e.g. cortisol (F) and cortisone (E) is catalysed by 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD) which exists as two isoforms. We have used human placental bed biopsies and an in-vitro cytotrophoblast cell culture system to examine the expression and activity of the 11 beta-HSD isoforms along with that of the glucocorticoid and mineralocorticoid receptors (GR and MR). Immunohistochemistry localized 11 beta-HSD1 to decidualized stromal cells and 11 beta-HSD2 to villous cytotrophoblast, syncytiotrophoblasts and trophoblast cells invading the placental bed and maternal vasculature. In primary cultures of human cytotrophoblast, 11 beta-HSD2, GR and MR mRNA were expressed. Low levels of 11 beta-HSD1 mRNA were noted in these cultured cells, but could be explained on the basis of contaminating, vimentin-positive decidual stromal cells (< or =5%). Enzyme activity studies confirmed the presence of a high-affinity, NAD-dependent dehydrogenase activity (K(m) 137 nmol/l and V(max) 128 pmol E/h/mg protein), indicative of the 11 beta-HSD2 isoform. No reductase activity was observed. The presence of functional MR and GR was determined using Scatchard analyses of dexamethasone and aldosterone binding (MR K(d) 1.4 nmol/l B(max) 3.0; GR K(d) 6.6 nmol/l B(max) 16.2 fmol/ng protein). The expression of 11 beta-HSD1 in maternal decidua and 11 beta-HSD2 in adjacent trophoblast suggests an important role for glucocorticoids in determining trophoblast invasion. The presence of the MR within trophoblast indicates that some of the effects of cortisol could be MR- rather than GR-mediated.
Many sheep in the United Kingdom are grazed on pastures deficient in cobalt and selenium. Proprietary products for selenium and cobalt supplementation often contain copper, which in certain breeds can induce copper toxicity. A soluble glass bolus has been manufactured to supply long term sustained release of cobalt and selenium similar to the commercially available Cosecure, but with the copper content being replaced by zinc. Sub clinical zinc deficiency has been suggested to be involved in disease conditions such as broken mouth periodontitis, footrot and mastitis. Therefore a long term continuous supply of zinc may be beneficial in these situations. This trial was designed to examine the effect of administering a zinc, cobalt and selenium soluble glass bolus on trace element status of over-wintered ewe lambs.
The fight against doping in sport using analytical chemistry is a mature area with a history of approximately 100 years in horse racing and at least 40 years in human sport. Over that period, the techniques used and the breadth of coverage have developed significantly. These improvements in the testing methods have been matched by the increased sophistication of the methods, drugs and therapies available to the cheat and, as a result, testing has been a reactive process constantly adapting to meet new threats. Following the inception of the World Anti-Doping Agency, research into the methods and technologies available for human doping control have received coordinated funding on an international basis. The area of biomarker research has been a major beneficiary of this funding. The aim of this article is to review recent developments in the application of biomarkers to doping control and to assess the impact this could make in the future.
Soluble, phosphate glass boluses containing copper, cobalt and selenium have proved successful in elevating and maintaining blood levels of these trace minerals in sheep (Driver et al, 1985 & 1986). In 1983 these boluses were marketed as the trace mineral supplement COSECURE. Recently trials with glasses of various solubilities were carried out and one formulation (Code EX) proved superior to all glasses tested to date (Driver et al, 1988). Last year the performance of this more soluble glass was compared with that of the commercial product, COSECURE, on a site which in previous years had shown severe copper deficiency. On day 0 (22 October), 20 Scottish-Blackface ewes each received one new (EX) bolus, another 20 received COSECURE boluses and a further 15 were left as untreated controls. Blood samples were taken at intervals over the following 330 days and assayed for plasma copper and serum caeruloplasmin for copper status and erythrocyte glutathione peroxidase (GSHPx) as a measure of selenium status. Boluses were recovered from culled ewes at 341 days after bolusing. The results were analysed by an analysis of variance.
1. The neural mechanisms involved in the control of prolactin and growth hormone secretion, body temperature and feeding in castrated male sheep were investigated by the lateral cerebroventricular injection of several putative neurotransmitters and carbachol. 2. Feeding was inhibited by 10 and 20 microgram carbachol and by 400 microgram histamine. 100 microgram Noradrenaline stimulated, but 200 microgram inhibited, feeding; however, both results were non‐significant compared with controls. 3. 20 microgram Carbachol elicited a highly significant rise in plasma growth hormone, suggesting a cholinergic component in the neural control of growth hormone in sheep. Noradrenaline, dopamine and 5‐hydroxytryptamine, but not melatonin, significantly depressed plasma prolactin concentration indicating a similar neural control for the hormone's release in sheep as in other species. 4. Deep body temperature appeared unaffected by any ofthe injected drugs. 5. The possible interrelationships between feeding behaviour and the circulating levels of growth hormone in ruminants is discussed. 6. A method for the radioimmunoassay of ovine growth hormone is described and validated.
Two soluble glass boluses (COSECURE) per animal were given to 19 (+ bolus), silage fed, growing cattle (160-350 kg) on April 16th 1984 (day 0). After 29 days these and 11 untreated (control) animals, matched for weight, breed and sex, were turned out on to a copper deficient upland pasture. On day 153 (Sept. 21) all the cattle were moved to a lowland pasture until day 196, when they were housed and fed silage. Blood samples and liveweights were taken on 5 occasions over 240 days. Copper status was assessed from plasma copper (Cu) and caeruloplasmin (CP) levels, and selenium status by erythrocyte glutathione peroxidase (GSHPx) activity.
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