No abstract

1. The sympathomimetic agent clenbuterol has a muscle-specific anabolic effect in normal and wasted muscles from animals. This trial was designed to examine the effect of the drug on the recovery of muscle strength and area after open medial meniscectomy. 2. A double-blind, completely randomized, placebo-controlled study was carried out on 20 healthy male patients. Muscle strength and cross-sectional area were determined before and after surgery. Patients were treated with drug or placebo for 4 weeks postoperatively and there was a 2 week washout period. 3. The results suggest that, in the operated leg, clenbuterol treatment is associated with a more rapid rehabilitation of strength in knee extensor muscles; in the unoperated leg, knee extensor strength increased above the initial values after 6 weeks (P = 0.01). However, in terms of absolute strength the differences were not significant between the two groups. 4. It is concluded that the data lend support to the proposition that clenbuterol has therapeutic potential in the treatment of muscle-wasting conditions.

In ten lambs (average live weight 33 kg), five offered 300 g/d (approximately 0 6 x maintenance; L) and five 900 g/d (1.8 x maintenance; H), tissue protein synthesis was measured by three procedures simultaneously. The techniques involved continuous infusion of leucine over 7-8 h followed by a terminal large dose of 115Nlphenylalanine during the last 30 or 60 min. Rates of protein synthesis were then calculated based on the free amino acid or 0x0-acid isotopic activity in either arterial, iliac venous blood or tissue homogenate for the continuous-infusion studies, or on plasma or tissue homogenate for the large-dose procedure. For muscle ( > 99 YO), and to a lesser extent skin amino or 0x0-acid were significantly less, more so at the lower intake. In contrast, for skin, a tissue dominated by export protein synthesis, values from the large-dose procedure (L 6.37 %/d, H 10.98 %Id) were similar to those derived with arterial or venous metabolites as precursor (L 5.23 and 693%/d, H 9.98 and 11.71 %/d for leucine), but much less than those based on homogenate data. Based on the large-dose technique, protein synthesis increased with intake in muscle (P < 0.001), skin (P = 0.009) and liver (26.7 v. 30.5 %/d; P = 0.029). The contributions of muscle and skin to total protein synthesis were approximately equal. The incremental efficiency of conversion for muscle of synthesized protein into deposition appeared to be similar to values reported for rodents.Tissue protein synthesis: Protein intake: LambThe dynamic nature of protein metabolism has been much investigated over the past two decades, with particular emphasis on understanding responses in tissues to a variety of nutritional and physiological stimuli. In both laboratory and commercial species most attention has focused on measurement of protein synthesis, for which a range of tracerbased techniques are available (see Lobley, 1988). Data for the larger species are more limited than for rodents, due to both accessibility and cost. Furthermore, much of the information on protein metabolism in individual tissues of farm animals is based on the continuous infusion of tracer amino acid developed by Waterlow and his colleagues (e.g. Garlick et al. 1973). The problem with this technique is that the various free amino acid pools of the body (e.g. vascular, interstitial, intracellular) become labelled to different

HighlightsFirst demonstration of between litter differences in play behaviour in pigs.Litter differences in play behaviour appear independent of overall activity levels.Litter differences in play behaviour associate strongly with post-natal growth.Pre-natal factors (particularly birth weight and BMI) associate positively with play behaviour.Pre-weaning play behaviour has potential as an indicator of positive welfare.

Analytical results are given for whey powders prepared on a commercial or semi-commercial scale by three companies. Altogether, five preparations enriched in ␤-lactoglobulin, four whey protein isolates and a fraction enriched in ␣-lactalbumin were analyzed for protein composition, including % ␤-lactoglobulin, ␣-lactalbumin, bovine serum albumin, casein (glyco) macropeptide and the main triglycerides. Protein composition was determined by high pressure gel permeation and reversed phase liquid chromatography and by capillary zone electrophoresis. The extent of modification of the native ␤-lactoglobulin structure was also measured through the degree of lactosylation and the fraction of accessible free sulphydryl groups. One significant finding was that the calculated recovery of protein following quantitation of the chromatogram or electropherogram was seldom above 90% and occasionally below 60% of that loaded onto the column or capillary, raising doubts as to the reliability of the analytical results. Extrapolation by linear regression to 100% recovery allowed estimates to be made of the true ␤-lactoglobulin composition of the samples. The nine samples could be placed into three distinct groups with estimat-ed true ␤-lactoglobulin weight % of 70.9 Ϯ 1.1, 62.0 Ϯ 3.4 and 39.5 Ϯ 4.9. Physico-chemical properties of the group of samples are reported elsewhere (Holt et al., 1999).The inter-laboratory comparisons involved the Royal Veterinary and Agricultural University (KVL), two laboratories of BDI (Lab1 and Lab2), NIZO food research (NIZO) and the Composition of whey protein isolates and fractions C. Holt et al. Figure 2 RP-HPLC analysis of commercial whey protein samples using the LRTL method. A. MDFwpi-1, B. MDFwpi-1a, C. MDFwpi-1b.Figure 3 Capillary zone electropherograms of selected samples as obtained by the KVL method. Within the b-Lg region, lactosylated forms have longer migration times than the native forms. on the Molecular Basis of the Aggregation, Denaturation, Gelation and Surface Activity of Whey Proteins (MADGELAS), CT96-1202. All other members of the MADGELAS group are thanked for their co-operation in the sample survey, of which this paper forms a part. The HRI work was supported by the Scottish Office Composition of whey protein isolates and fractions C. Holt et al.