Polyunsaturated fatty acids are normally hydrogenated by microorganisms in the rumen. Because of this hydrogenation ruminant triglycerides contain very low proportions of polyunsaturated fatty acids. A new process is described whereby polyunsaturated oil droplets are protected from ruminal hydrogenation by encapsulation with formaldehyde-treated protein. The formaldehyde-treated protein resists breakdown in the rumen thereby protecting the fatty acids against microbial hydrogenation. When these protected oils are fed to ruminants the formaldehydeprotein complex is hydrolyzed in the acidic conditions of the abomasum and the fatty acids are absorbed from the small intestine. This results in substantial changes in the triglycerides of plasma, milk and depot fats, in which the proportion of polyunsaturated fatty acids is increased from 2-5% to 20-30%. These effects are observed in the plasma and milk within 24-48 hr of feeding while a longer period is necessary to alter the composition of sheep depot fat. The implications of these findings are discussed in relation to human and ruminant nutrition.

The effect of change in environment on plasma cortisol and blood glucose levels in sheep has been studied in the following situations: movement from grazing paddock to small enclosed yards, movement from grazing paddock to indoor animal quarters, and short periods of transport. Consistent large increases in plasma cortisol values were recorded in previously grazing animals, but the degree of elevation during road transport was usually less in "trained" animals housed indoors. Previous undernourishment or fasting increased the changes in plasma cortisol level in response to stress. Individual variation in plasma cortisol response between animals was considerable. Pronounced, but variable, increases in blood glucose occurred in all experiments except those in which exercise (walking) was associated with the brief stressful situation created by moving animals from the paddock into an enclosed yard. It is concluded that movement to an unfamiliar environment is an emotionally stressful situation, but that there are important differences in the quantitative adrenal cortical response between the grazing animal and experimental animals housed indoors and already subjected to a series of novel environmental changes. It is further suggested that exercise during a short period of stress may modify or prevent the normal hyperglycaemic response to adrenaline release. These experiments provide further support for the conclusion that the elevated plasma cortisol levels observed in the "stress syndrome" of pregnancy toxaemia are primarily a response to physical or emotional stress, rather than to the nutritional stress of fasting or severe undernutrition.

IntroductionThe effects of parathyroid hormone were studied on Ca" fluxes in canine renal proximal tubular basolateral membrane vesicles (BLMV). Efflux of Ca2+ from preloaded BLMV was found to be stimulated by an external Na' gradient, and this was inhibited by the Na' ionophore, monensin, and enhanced by intravesicular negative electrical potentials, which indicated electrogenic Na+/Ca2" exchange activity. There was a Na' gradient independent Ca2+ flux, but membrane binding of Ca2" was excluded from contributing to the Na' gradient-dependent efflux. The Na' gradient-dependent flux of Ca2" was very rapid, and even 2-and 5-s points may not fully represent absolute initial rates. It was saturable with respect to the interaction of Ca2" and Na' with an apparent (5 s) K. for Na'-dependent Ca2" uptake of 10 ,uM, and an apparent (5 s) V.,.,, of 0.33 nmol/mg protein per 5 s. The Na' concentration that yielded half maximal Ca2" efflux (2 s) was 11 mM, and the Hill coefficient was two or greater. Both Na+ gradient dependent and independent Ca2" efflux were decreased in BLMV prepared from kidneys of thyroparathyroidectomized (TPTX) dogs, and both were stimulated by parathyroid hormone (PTH) infusion to TPTX dogs. BLMV from TPTX dogs exhibited significantly reduced maximal stimulation of Na+ gradient-dependent Ca2+ uptake with an apparent (5 s) V,,, of 0.23 nmol/mg protein per 5 s, but the apparent K. was 8 ,uM, which was unchanged from normal. The Na+ gradient independent Ca2+ uptake was also reduced in BLMV from TPTX dogs compared with normal. Thus, PTH stimulated both Na+/Ca2" exchange activity and Na+ independent Ca2" flux. In vivo, the latter could result in an elevation of cytosolic Ca2" by PTH, and this might contribute to the observed decrease in solute transport in the proximal tubule. (33). Renal medullary tissue was removed from the kidneys, and renal cortical tissue was diced and homogenized using a Potter-Elvehjem Teflon homogenizer in homogenizing buffer (250 mM sucrose, 20 mM Tris base, and 1 mM EGTA adjusted to pH 7.6), 20 ml/g of tissue.The suspension was then further homogenized using a Polytron homogenizer (Brinkman Instruments, Westbury, NY), setting six for three bursts of 30 s. After samples were taken for analysis of protein and enzyme content, the homogenate was centrifuged at 2,500 g for 15 min and the pellet discarded. The suspension was then spun at 24,000 g for 20 min and the supernatant decanted. The soft portion of the pellet was resuspended in the homogenizing buffer to a value of 1.3 ml/g initial tissue and hand homogenized for seven strokes with a Dounce homogenizer. The suspension was then diluted and thoroughly mixed with 1.6 ml/g initial tissue of 100% Percoll (Pharmacia Fine Chemicals, Upsala, Sweden) and the homogenizing buffer, 17 ml/g initial tissue (final Percoll concentration 8%). The suspension was then centrifuged at 30,000 g for 35 min. This produced a density gradient of Percoll from 1.005 to 1.125 g/ml. The fraction corresponding to an opaque band and density 1.030-1...

1. The effects of thyrotrophin in vitro on the incorporation of [(14)C]-glucose, -glycerol, -palmitate and -oleate into the lipids of thyroid tissue were examined. 2. Thyrotrophin increased the incorporation of these (14)C-labelled precursors into phosphatidylinositol specifically. 3. Thyrotrophin also increased the proportion of (14)C radioactivity from labelled glucose, glycerol, palmitate and oleate incorporated into the 1,2-diglycerides. 4. The addition of thyrotrophin to thyroid slices for 10min., after 2hr. of prelabelling with [(14)C]glycerol, also increased the proportion of (14)C radioactivity incorporated into the 1,2-diglyceride fraction. 5. After incubation of thyroid tissue with [1-(14)C]palmitate, thyrotrophin caused a two- to three-fold increase in the specific radioactivity of palmitate isolated from phosphatidylinositol and 1,2-diglycerides. In contrast, the specific radioactivity of palmitate isolated from the choline and ethanolamine phosphoglycerides, 1,3-diglycerides and triglycerides was not increased by thyrotrophin.