Kg Of Muscle Research Articles

Chemical and LC–MS-based lipidomics analyses revealed changes in lipid profiles in hairtail (Trichiurus haumela) muscle during chilled storage

Chemical and liquid chromatography–mass spectrometry (LC–MS)-based lipidomics techniques were used to investigate the alternations of lipid profiles in hairtail (Trichiurus haumela) muscle after chilled storage for six days. The chemical results showed that the peroxide values (PVs) and thiobarbituric acid reactive species (TBARS) content in the muscle increased significantly, from 0.43 meq/kg of lipids and 0.86 mg malondialdehyde (MDA)/kg of muscle to 8.36 meq/kg and 10.69 mg MDA/kg, respectively, after six days of chilled storage. LC–MS-based lipidomics analyses detected 1446 lipids in hairtail muscle tissues assigned to 26 lipid categories, including 257 triglycerides (TGs), 232 phosphatidylcholines (PCs), 149 phosphatidylethanolamines (PEs), and 78 ceramides (Cers), among other classes. In total, 175 and 67 differentially abundant lipids (DALs) accumulating at low and high abundance levels, respectively, were detected in chilled stored hairtail (CSH) compared to fresh (FH) samples. Among the DALs, the PCs, PEs, and TGs/diglycerides (DGs) as predominant lipid components were more prone to oxidation/hydrolysis, likely owing to their highly unsaturated properties. The apparent alterations between the CSH and FH samples might result from lipid lipolysis, modifications of main- and side-chains, backbone cleavage, and/or the decomposition of lipids during chilled storage.

Leaping small fish out-power breaching whales

When Emmett Johnston from Queen's University, Belfast, UK, attached a motion sensing tag to a basking shark off the Irish coast, he expected the piece of kit to have a sedate ride. Nothing prepared Johnston and colleagues for the rollercoaster that the sensor went on in practice. ‘Having retrieved it, we watched the video and, to our amazement, the movie ended with the shark suddenly accelerating up through the water column, hitting the water surface at 5 m s−1 and breaching for about a second’, says Lewis Halsey from the University of Roehampton, London, UK. The massive fish was behaving more like cavorting gray whales or leaping salmon than the lethargic filter feeder it was meant to be. The team calculated that each leap could use up to 1/17th of the animal's daily metabolic budget (doi:10.1098/rsbl.2018.0537). However, after reviewing movies of breaching basking sharks filmed by observers on land, Halsey suspected that it might be possible to calculate the amount of energy an aquatic animal requires to make it into the air from the footage. ‘I thought there must be lots of video available of other aquatic species breaching’, says Halsey. Could he find a way to calculate how much power it takes for fish, whales and dolphins to surge out of the water from movies shot by citizen scientists?Halsey turned to the millennials’ TV channel of choice. ‘I kept searching YouTube with names of fish and cetaceans and various words for jumping until I couldn't find any more’, he chuckles, recalling how, eventually, he ended up with almost 30 clips of species ranging from a 20 cm long African tetra to a 13 m long humpback whale. Then Halsey teamed up with Gil Iosilevskii from the Technion, Israel, to calculate the animals’ sheer power and speed as they burst out of the water. ‘Gil did the hardcore maths’, recalls Halsey, adding, ‘He is one of the few people around with the capacity to develop the equations we used to estimate power output from the videos’. Halsey then estimated the animals’ sizes, measured the length of time each animal was airborne and determined several other values before plugging them into Iosilevskii's equations.Amazingly, the common bottlenose dolphins and spinner dolphins (both ∼2 m long) hit the highest take-off speeds of ∼10.7 m s−1 (38.5 km h−1), with the smaller species achieving progressively lower speeds; the slowest leaps were performed by the diminutive African tetra, which took off at only 4.4 m s−1. Meanwhile, the largest creatures, including the basking shark, great white shark and massive humpback whale hit speeds ranging from 5.8 to 9.1 m s−1; they didn't come close to challenging the dolphins’ speed. However, when the duo compared the peak muscle power of the animals, it was clear that the smaller species – including mackerel, mullet and the common bottlenose dolphin – generated the highest muscle powers of over 50 W per kg of muscle when jetting out of the waves. In contrast, the heftier great white shark, orca and humpback whale, managed less than 10 W per kg of muscle.Halsey suspects that the smaller species’ powerful departures ‘represents an estimate of a universal upper limit to power output’, adding that their pound-for-pound power was very similar to that of top human athletes performing right at their physical limits. ‘When these animals are breaching at their fastest, they might well be performing at maximum effort’, says Halsey.

Siltuximab Reverses Muscle Wasting In Patients With Multicentric Castleman's Disease

IntroductionMulticentric Castleman's disease (MCD) is a rare lymphoproliferative disease characterized by fevers, night sweats, fatigue, anorexia, and wasting. Interleukin-6 (IL-6) plays a pivotal role in MCD and is involved in muscle wasting. Siltuximab (CNTO328) is a chimeric IgG1κ mab that binds IL-6 and prevents its interaction with IL-6 receptors. We analyzed prospectively collected computed tomography (CT) scans to determine siltuximab's effects on muscle mass. MethodsCT scans of MCD patients (pts) from a phase 1 siltuximab study were studied for changes in body composition from siltuximab treatment. Pts (n=37) were treated with CNTO328 q weekly, 2 wks or 3 wks at doses ranging from 2.8 to 11 mg/kg, and 34/37 pts had CT scans that were suitable for evaluating body composition. The median age was 49 (range 18-76) with 18 M/16 F. Median body weight was 78 kg (mean 87 kg, range 40 to 170 kg). Eleven pts had not received prior treatment; the other 23 pts had a median of 2 prior therapies, range 1 to 5. Pts' histology was hyaline vascularity (n=17), plasmacytic (n=15), and mixed cellularity (n=2). CT scans for each pt at each time point in their treatment were landmarked at the axial 3rd lumbar vertebra (L3). L3 images were then tissue cross sectional area analyzed using Slice-O-Matic® (Tomovision, Montreal, Canada) with Hounsfield units (HU) set at different levels for each tissue: skeletal muscle within the range of -29 HU to 150 HU, visceral adipose tissue within -150 HU to -50 HU, intramuscular adipose tissue within -190 HU to -30 HU, and subcutaneous adipose tissue within -190 HU to -30 HU. Tissue areas were used to estimate tissue mass Shen et al. 2004 J Appl Physiol 97:2333-2338). ResultsThe median duration of treatment in this phase I study was 703 days (range 21 to 1843 days). During siltuximab treatment 38% of pts gained > 1 kg of muscle, mean 2.3 kg ± 1.1 kg (all mean values reported as mean±SD), 47% of pts had a stable muscle mass, muscle gain or loss less than 1 kg, mean 0.2 kg ± 0.5 kg and 15% of pts lost more than 1 kg, mean loss 3.1 ± 1.7 kg. Over the entire patient population (n=34) the mean gain in muscle was 0.5 kg (median 0.6 kg, range -5.5 to 4.4 kg); and the mean gain in adipose tissue was 3.1 kg (median 3.05, range -13.8 to 35.8 kg). By MCD histology the gain in muscle was 0.25 kg for hyaline vascular, 0.33 kg for mixed cellularity, and 0.85 kg for plasmacytic. Changes in fat mass by MCD histology was 5.1 kg for hyaline vascular, 5.8 for mixed cellularity, and 3.8 kg for plasmacytic. By Cheson radiologic disease response criteria the change in muscle mass was 0.9 kg for pts with partial response (PR, n=11), 0.5 kg for patients with stable disease (SD, n=22), and -3.7 kg for the one patient with progressive disease (PD). The change in fat mass was 8.5 kg for patients with PR (n=11), 2.85 kg for patients with SD (n=22) and -0.6 kg for the one patient with PD. At the recommended phase II dose of 11mg/kg q 3 wks (n=17), the mean gain in muscle mass was 0.6 kg (median 0.9 kg, range -5.5 kg to 4.4 kg). The pattern of muscle and fat mass gain was interesting in that the fat mass increased first followed by a delay and then muscle gains occurred. Pts who continued to respond to siltuximab continued to gain muscle mass up to the time that they were censored. ConclusionsIn addition to objective responses that were durable in MCD (median duration of response was not reached at follow-up of 29.4 months), siltuximab caused reversal of muscle wasting in 38% of patients, stabilization of muscle wasting in another 47% and in only 15% of patients did muscle wasting worsen. This stabilization and improvement in muscle wasting could lead to functional status improvements in MCD patients. Disclosures:Kurzrock:Janssen Research & Development: Research Funding. van Rhee:Janssen Research & Development: Research Funding. Ming:Janssen Research & Development: Employment. Vermeulen:Janssen Research & Development: Employment; Johnson & Johnson: Equity Ownership.

Effects of abiraterone acetate and enzalutamide on muscle and adipose mass in men with metastatic castration-resistant prostate cancer (mCRPC).

5088 Background: Abiraterone acetate (AA) and enzalutamide (MDV3100), two androgen receptor-directed compounds, have been shown to improve survival for patients with metastatic castration-resistant prostate cancer (mCRPC) progressing after Docetaxel.. Since these drugs might be used at an early-stage in the future, and skeletal muscle (SM) and adipose tissue (AT) are known to be prognosis parameters, the aim of this study was to evaluate the body composition changes in patients with mCRPC treated with AA and MDV3100. Methods: Patients included in AFFIRM (n=62 treated with MDV3100 and placebo n=28) and COU-AA-301 (n=24 treated with AA+Prednisone (P)10mg/day and placebo+P n= 13) trials at the Institute Gustave Roussy were included in the analysis. Cross-sectional areas (cm2) of visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT) and SM were assessed by computed tomography imaging at 3rd lumbar vertebra and were indexed for height (cm2/m2) with Slice-O-Matic software V4.3 at baseline, 3, 6 and 12 months of treatment. The data from patients treated with AA or MDV3100 were compared to placebo-patients and tissues changes were compared to baseline. We used the validated sarcopenic definitions as SM index less than 52.4 (cm2/m2). Results: For all cohort, median age was 69 years (range: 48-83), median weight was 79 kg (range: 47-150) and median BMI was 25.9 kg/m2(range: 18-46). At inclusion, 74 patients (58%) were overweight or obese (BMI>24.9 kg/m2), and only 2 patients were underweight (BMI<18.5kg/m2). 97 patients (81%) were sarcopenic, and 56 (75%) of overweight or obese patients were sarcopenic. Over 3 months, the patients from the entire cohort lost muscle mass (mean change: 4.5±7.5% (» 0.7 kg of muscle)) (P=0.01) . A non significant loss of SAT -4.6±19.2% and a non significant increase of VAT (+10.7±50.3% ) were observed. A similar pattern was observed at 6 months. There was no significant difference between body composition changes in treated groups and placebo. Conclusions: Sarcopenia is highly prevalent in patients with advanced CRPC. Unexpectedly, no difference in body composition changes was observed between patients treated with MDV3100 or AA and placebo.

Accelerated muscle and adipose tissue loss may predict survival in pancreatic cancer patients: the relationship with diabetes and anaemia

Weight loss leading to cachexia is associated with poor treatment response and reduced survival in pancreatic cancer patients. We aim to identify indicators that allow for early detection that will advance our understanding of cachexia and will support targeted anti-cachexia therapies. A total of fifty pancreatic cancer patients were analysed for skeletal muscle and visceral adipose tissue (VAT) changes using computed tomography (CT) scans. These changes were related to physical characteristics, secondary disease states and treatment parameters. Overall, patients lost 1.72 (SD 3.29) kg of muscle and 1.04 (SD 1.08) kg of VAT during the disease trajectory (413 (SD 213) d). After sorting patients into tertiles by rate of VAT and muscle loss, patients losing VAT at > -0.40 kg/100 d had poorer survival outcomes compared with patients with < -0.10 kg/100 d of VAT loss (P= 0.020). Patients presenting with diabetes at diagnosis demonstrated significantly more and accelerated VAT loss compared with non-diabetic patients. In contrast, patients who were anaemic at the first CT scan lost significantly more muscle tissue and at accelerated rates compared with non-anaemic patients. Accelerated rates of VAT loss are associated with reduced survival. Identifying associated features of cachexia, such as diabetes and anaemia, is essential for the early detection of cachexia and may facilitate the attenuation of complications associated with cachexia.

An Evidence-Based Review of Exercise and Metabolic Syndrome

An Evidence-Based Review of Exercise and Metabolic Syndrome

Efectos de la aplicación del Kinesio taping™ en el diafragma en el resultado la cicloergoespirometría y la prueba marcha de 6 minutos

Objective The aim of the study was to verify whether the application of the anterior diaphragmatic technique of Kinesio™ taping (KT) improves the performance in sports in healthy subjects. Design Repeated measures with randomization in order of tests, with or without KT. Material and methods The study sample included 17 subjects, 10 men and 7 women, 21 to 38 years old. A cycloergospirometric or graded exercise test (bike test with spirometry) and 6 minute walk test were performed. The subjects came on two separate days, 7 days apart, performing the KT tests on one of the days and the tests without the KT on the other. In the first place, muscle weight was calculated through anthropometry and bioimpedance. During the cycloergospirometric test, variables that included the maximal oxygen consumption per kg of muscle achieved on the graded exercise test were measured. The results analyzed from the 6 minute walk test included distance covered and work performed (distance per kg of muscle mass). Results The KT did not produce any significant changes in the variables measured during the graded exercise test or the 6 minute walk test. A significant learning effect was observed only for the 6 minute walking test results, both for the distance covered (Distance 1st test = 834.69 ± 107.03 m; 2nd test = 891.12 ± 93.91 m; p = .007) and for the work achieved ( P = .008). Conclusions There was no significant effect of diaphragmatic KT on results of the graded exercise test and 6 minute walk test. There is a learning effect for the 6 minute walk test.

Effect of everolimus therapy on skeletal muscle wasting in patients with metastatic renal cell carcinoma (mRCC): Results from a placebo-controlled study.

319 Background: We have previously reported that sorafenib induces muscle wasting in mRCC (Antoun, JCO 2010). As everolimus exerts its antineoplastic through inhibition of the mammalian target of rapamycin (mTOR), a key element of intracellular signalling of protein synthesis in skeletal muscle, we hypothesized that muscle wasting would be also an important side effect of everolimus therapy. Methods: All patients with mRCC enrolled in RECORD 1 (everolimus (E) or placebo (P) post TKI failure) in IGR (n=40) were analyzed for this study. Patients were eligible if at least 2 CT scans were available. CT image analysis, which has high precision and specificity for evaluation of specific muscles, was used to define change in total skeletal muscle. The third lumbar vertebra (L3) was chosen as a landmark. Images were analyzed using Slice-O-Matic software V4.3 (Tomovision). Tissue Hounsfield unit thresholds were employed: −29 to +150 for skeletal muscle. Subsequently, tissue cross-sectional areas (cm2) were computed. Results: 35 patients (83% male, median age 60y) were evaluable, 10 on P and 25 on E. In addition, 9 patients initially on P could cross to E (as per protocol) and were analyzed both on P and on E. Median durations of treatment were 79 and 263 days respectively on P and E. Placebo patients had stable body weight, with no significant mean gain or loss of muscle. By contrast, patients on E lost body weight over time: −2.5±3.6 kg by 83 d (p=0.02), −4.9±5.7 (p=0.005) by 167 d and –5.0±7.6 kg (p=0.02) by 286 d. E patients progressively lost skeletal muscle compared .with baseline from −2.5±5.9% at 83d (p=0.06), to −4.0±7.5% at 167d (p=0.03) and −4.8±6.8% at 263d (p=0.01). Interstingly, the 9 patients who had maintained body weight (+2.0 kg) and muscle (+2.7%) whilst on placebo, and crossed to E, promptly lost weight (−4.8 kg, p&lt;0.03) and skeletal muscle (−5.3%) (about 1.5 kg of muscle) when crossed to E. Conclusions: Body weight and muscle wasting are induced by everolimus in mRCC, and are not related to progressive disease. These changes increase over time. Relation between these changes and outcome will be presented at the meeting. [Table: see text]

Nutritional intervention with fish oil provides a benefit over standard of care for weight and skeletal muscle mass in patients with nonsmall cell lung cancer receiving chemotherapy

Involuntary weight loss is a major contributor to mortality and morbidity in patients with advanced cancer. Nutritional intervention with fish oil (FO)-derived eicosapentaenoic acid (EPA) may prevent deterioration of body composition. This study compared intervention with FO with standard of care (SOC; no intervention) with regard to weight, skeletal muscle, and adipose tissue in newly referred patients with nonsmall cell lung cancer from the time of initiation to completion of first-line chemotherapy. Forty patients completed the study; there were 16 in the FO group (dose of 2.2 g of EPA/day) and 24 patients in the SOC group. Skeletal muscle and adipose tissue were measured using computed tomography images. Blood was collected and weight was recorded at baseline and throughout chemotherapy. Patients in the SOC group experienced an average weight loss of 2.3 ± 0.9 kg whereas patients receiving FO maintained their weight (0.5 ± 1.0 kg) (P = .05). Patients with the greatest increase in plasma EPA concentration after FO supplementation were found to have the greatest gains in muscle (r(2) = 0.55; P = .01). Approximately 69% of patients in the FO group gained or maintained muscle mass. Comparatively, only 29% of patients in the SOC group maintained muscle mass, and overall the SOC group lost 1 kg of muscle. No difference in total adipose tissue was observed between the 2 groups. Nutritional intervention with 2.2 g of FO per day appears to provide a benefit over SOC, resulting in the maintenance of weight and muscle mass during chemotherapy.

Disparity in regional and systemic circulatory capacities: do they affect the regulation of the circulation?

In this review we integrate ideas about regional and systemic circulatory capacities and the balance between skeletal muscle blood flow and cardiac output during heavy exercise in humans. In the first part of the review we discuss issues related to the pumping capacity of the heart and the vasodilator capacity of skeletal muscle. The issue is that skeletal muscle has a vast capacity to vasodilate during exercise [approximately 300 mL (100 g)(-1) min(-1)], but the pumping capacity of the human heart is limited to 20-25 L min(-1) in untrained subjects and approximately 35 L min(-1) in elite endurance athletes. This means that when more than 7-10 kg of muscle is active during heavy exercise, perfusion of the contracting muscles must be limited or mean arterial pressure will fall. In the second part of the review we emphasize that there is an interplay between sympathetic vasoconstriction and metabolic vasodilation that limits blood flow to contracting muscles to maintain mean arterial pressure. Vasoconstriction in larger vessels continues while constriction in smaller vessels is blunted permitting total muscle blood flow to be limited but distributed more optimally. This interplay between sympathetic constriction and metabolic dilation during heavy whole-body exercise is likely responsible for the very high levels of oxygen extraction seen in contracting skeletal muscle. It also explains why infusing vasodilators in the contracting muscles does not increase oxygen uptake in the muscle. Finally, when approximately 80% of cardiac output is directed towards contracting skeletal muscle modest vasoconstriction in the active muscles can evoke marked changes in arterial pressure.

Counterpoint: There is not capillary recruitment in active skeletal muscle during exercise

The notion that a substantial proportion of capillaries do not contain moving red blood cells (RBCs) in muscle at rest but are “recruited,” i.e., begin flowing with RBCs during contractions, is one basis for our present understanding of blood-muscle exchange during exercise ([20][1], [28][2]).

Effect of Low-Dose Radiation on Microbiological, Chemical, and Sensory Characteristics of Chicken Meat Stored Aerobically at 4°C

The effect of γ-radiation (0.5, 1, and 2 kGy) on the shelf life of fresh skinless chicken breast fillets stored aerobically at 4°C was evaluated. Microbiological, chemical, and sensorial changes occurring in chicken samples were monitored for 21 days. Irradiation reduced populations of bacteria, i.e., total viable bacteria, Brochothrix thermosphacta, lactic acid bacteria (LAB), and the effect was more pronounced at the highest dose (2 kGy). Pseudomonads, yeasts and molds, and Enterobacteriaceae were highly sensitive to γ-radiation and were completely eliminated at all doses. Of the chemical indicators of spoilage, thiobarbituric values for nonirradiated and irradiated aerobically packaged chicken samples were in general low (<1 mg of malonaldehyde per kg of muscle) during refrigerated storage for 21 days. With regard to volatile amines, both trimethylamine nitrogen (TMA-N) and total volatile basic nitrogen (TVB-N) values for nonirradiated aerobically packaged chicken increased steeply, with final values of ca. 20.3 and 58.5 mg N/100 g of muscle, respectively. Irradiated aerobically packaged chicken samples had significantly lower TMA-N and TVB-N values (P < 0.05) of ca. 2.2 to 3.6 and 30.5 to 37.1 mg N/100 g of muscle, respectively, during refrigerated storage for 21 days. Of the biogenic amines monitored, only putrescine and cadaverine were detected in significant concentrations in both nonirradiated and irradiated chicken samples, whereas histamine formation was noted only in nonirradiated samples throughout storage. On the basis of sensorial evaluation, low-dose irradiation (0.5 and 1.0 kGy) in combination with aerobic packaging extended the shelf life of fresh chicken fillets by ca. 4 to 5 days, whereas irradiation at 2.0 kGy extended the shelf life by more than 15 days compared with that of nonirradiated chicken.

Composição física da carcaça e qualidade da carne de bovinos superjovens inteiros Charolês e mestiços Charolês x Nelore

The physical composition of the carcass and the qualitative characteristics of the meat of 12 young bulls from the genetic groups Charolais (C), 5/8 Charolais 3/8 Nellore (5/8CN) and 11/16 Charolais 5/16 Nellore (11/16CN) were evaluated. The animals were feedlot finished and slaughtered at 17 months, with a diet containing roughage:concentrate relation of 70:30 during the first 84 days and 55:45 during the last 44 days, with 13% of crude protein. The experimental design was completely randomized, with three repetitions. There was no observed of the genetic group effect on carcass composition as for weights in kg of muscle (P= 0.7611), fat (P=0.5451) and bone (P=0.2638), on percentages of muscle (P= 0.2252), fat (P=0.5229) and bone (P=0.4053). The eatable portion was not influenced (P= 0.3707) by the genetic group. The meat color was classified as "lightly dark red", and there was no significant difference (P=0.5191) between the studied genetic groups. The meat of C steers presented marbling (P=0.373) classified as traces (3.0 points) in relation to genotypes 5/8CN and 11/16CN, classified as light (5.0 and 5.5 points, respectively). The genetic group did not influence in the juiciness (P=0.9390), tenderness (P=0.3636) and on the shear force (P=0.6632).

Composição física da carcaça e qualidade da carne de vacas de descarte de diferentes grupos genéticos terminadas em confinamento com distintos pesos

O objetivo neste experimento foi avaliar a composição física e as características qualitativas da carne de vacas de descarte mestiças da segunda (G2 - 3/4Charolês (C) 1/4Nelore (N) e 3/4NC) e terceira gerações (G3 - 5/8CN e 5/8NC) de cruzamento rotativo Charolês - Nelore terminadas em confinamento e abatidas com 465, 507 ou 566 kg. Os animais apresentaram na média, no início do confinamento 8,5 anos, 388,6 kg e 2,35 pontos de escore da condição corporal. A dieta alimentar, com relação volumoso:concentrado de 48:52, continha 12,5% de proteína bruta e 2,99 Mcal de energia digestível por kg de matéria seca. Houve redução da participação de ossos (16,55; 15,84 e 12,72%) e músculo (63,50; 60,05; 60,69%) e incremento da percentagem de gordura (19,85; 24,32; 28,08%, respectivamente) na carcaça com o aumento do peso de abate. O ganho de peso da porção comestível da carcaça entre os pesos de abate extremos foi 77,36 kg, sendo 37,32 kg de músculo (48,24%) e 40,04 kg de gordura (51,76%). A maciez, quando avaliada pela força de cizalhamento, melhorou significativamente na carne dos animais abatidos com peso mais elevado (4,94, 4,89 e 3,89 kgf/cm³, respectivamente). A carne das vacas 5/8NC apresentou coloração mais escura (2,87 pontos) que a das vacas 5/8CN (4,0 pontos). A carne dos animais da G3 foi mais macia que a dos animais G2 (4,16 vs 4,99 kgf/cm³). Carne mais suculenta foi observada em vacas 5/8NC que nas 5/8CN (6,49 vs 4,16 pontos), em razão da menor perda à cocção das 5/8NC (17,61 vs 23,33%). O aumento do peso de abate de vacas de descarte é um bom recurso para elevar rapidamente a produção de carne bovina, melhorando inclusive significativamente sua qualidade.

Cellular mechanisms causing loss of muscle mass in kidney disease

In stable adults or patients with kidney disease, the daily turnover of cellular proteins is very large, amounting to the quantity of protein in 1 to 1.5 kg of muscle. Consequently, even a small but persistent increase in protein degradation or decrease in protein synthesis leads to a substantial loss of muscle mass. In chronic kidney disease, the pathway that degrades muscle protein is the ubiquitin-proteasome system. We tested whether either of two complications of chronic kidney disease, metabolic acidosis or insulin resistance accelerates the loss of muscle protein. Metabolic acidosis activates the ubiquitin-proteasome system and this can explain an large number of clinical conditions in which metabolic acidosis also causes loss of muscle protein. Insulin deficiency as a model of insulin resistance also activates the ubiquitin-proteasome system. Both complications also activate caspase-3 and we found that this protease performs a critical initial step in breaking down the complex structure of muscle to provide actin, myosin and fragments of these proteins as substrates for the ubiquitin-proteasome system. Defects in insulin signalling processes can activate both caspase-3 and the ubiquitin-proteasome system to degrade muscle protein. Understanding mechanisms that activate protein breakdown will lead to therapies that successfully prevent the loss of muscle mass in patients with kidney disease.

Performance of the fat-tailed Barbarine sheep in its environment: adaptive capacity to alternation of underfeeding and re-feeding periods. A review

The Barbarine sheep is characterised by a fat-tail, whose mass varies between 1 and 4 kg. Its management is traditionally based on spring mating. The ability of this fat-tailed ewe to mobilise its body reserves has been demonstrated in lactation and the dry period by experimentally varying the food supply. The severely underfed ewe (200 g oat hay) can survive 161 days and lose 36% of its body weight (BW), with a change of 8.8 kg of dissected adipose tissue (AT) and 3.4 kg of muscle. It reached this stage with an empty BW of 24 kg containing 12% of AT. The fat tail exerts a role as a body reserve mainly through its mass rather than through its ability to be rapidly mobilised. In such situations, plasma NEFA and 3-hydroxybutyrate concentrations are first almost doubled, then decline in permanently underfed ewes, showing the ability of Barbarine ewes to adjust their lipid metabolite concentration in order to limit the toxic effects of high concentrations and therefore prolong survival. By the end of a re-feeding period, Barbarine ewes returned to their initial BW, lipid and protein mass. This breed has a good fertility, which can, however, be depressed in cases of undernutrition. However, if the mating period is extended, the overall reproductive performance is generally satisfactory. Poor nutrition during pregnancy may reduce lamb birth weight and affect subsequent growth, however, in traditional conditions, ewe and lamb mortality rates are surprisingly low in this breed. In normal birth weighted lambs, the post-weaning growth performances of grazing lambs are moderate but in feedlot conditions the conversion rate is rather low and carcass adiposity is high. This review shows that the Barbarine sheep, and specially the ewe, is well adapted to the local conditions mainly because of its high fertility and its ability to deposit and mobilise body reserves.

Mechanisms activating proteolysis to cause muscle atrophy in catabolic conditions

The daily turnover of cellular proteins is the same as the amount of protein contained in 1 to 1.5 kg of muscle. Consequently, even a small but persistent increase in protein degradation or decrease in protein synthesis results in substantial loss of muscle mass, as shown in patients with trauma, sepsis, or kidney failure. Activation of the ubiquitin-proteasome proteolytic system in muscle is the major pathway contributing to loss of muscle mass in catabolic illnesses. At least 3 signals have been identified as causing loss of muscle mass: acidosis, defective insulin action, and glucocorticoids. The influence of inflammatory cytokines on this system in muscle is more complicated because cytokines can suppress the system unless glucocorticoids are present. An initial reaction that breaks down muscle appears to involve caspases. Such information could lead to therapies that successfully prevent the loss of muscle mass in catabolic illnesses. © 2003 by the National Kidney Foundation, Inc.

Kinetics of circulating antigens in pigs experimentally infected with Taenia solium eggs.

Three groups of four piglets were experimentally infected with different doses (10(3), 10(4) and 10(5)) of Taenia solium eggs whereas a fourth group of two pigs received gravid proglottids. At autopsy 6 months post infection, the two latter pigs were heavily infected with more than 3000 living cysts per kg of muscle. Ten of the 12 other pigs harboured light infections, i.e. between 2 and 107 cysticerci, 42.4% of which were degenerated. The two remaining pigs had no detectable cysts at post mortem examination. Circulating antigens (CA) were detected in the sera of all pigs harbouring living cysticerci using a monoclonal antibody based ELISA. CA were first detected between 2 and 6 weeks post infection and remained present generally throughout the entire observation period even in pigs carrying only five to eight living cysts, although strong fluctuations of the level of CA were observed in some pigs. In animals without living cysts at post mortem CA were only detected for a short period and disappeared presumably when the cysticerci became degenerated. The minimum number of living cysts, which could be detected using this ELISA, was 1.

Mechanisms activated by kidney disease and the loss of muscle mass

The daily turnover of cellular proteins is large, with amounts equivalent to the protein contained in 1.0 to 1.5 kg of muscle. Consequently, even a small, persistent increase in the rate of protein degradation or decrease in protein synthesis will result in substantial loss of muscle mass. Activation of protein degradation in the ubiquitin-proteasome system is the mechanism contributing to loss of muscle mass in kidney disease. Because other catabolic conditions also stimulate this system to cause loss of muscle mass, the identification of activating signals is of interest. A complication of kidney disease, metabolic acidosis, activates this system in muscle by a process that requires glucocorticoids. The influence of inflammatory cytokines on this system in muscle is more complicated, as evidence indicates that cytokines suppress the system, but glucocorticoids block the effect of cytokines to slow protein breakdown in the system. New information identifying mechanisms that activate protein breakdown and the rebuilding of muscle fibers would lead to therapies that successfully prevent the loss of muscle mass in kidney disease and other catabolic illnesses. © 2001 by the National Kidney Foundation, Inc.

Grass valorisation and muscular characteristics of blonde d'Aquitaine steers

The blonde d'Aquitaine breed, the males of which are traditionally raised as young steers in intensive systems, is spreading beyond its region of origin. In pasture regions these males could be introduced into more extensive grazing systems. The purpose of this study is to assess the capa- bility of these animals to valorise forage resources and also the characteristics of the carcasses pro- duced and of the muscles concerned when considering meat tenderness. The study used young weaned bulls reared as beef animals and slaughtered at 33 months of age ( n = 22 and 24). These beef animals use 2 very different types of pasture during the pasturing seasons (April-November). During the first winter period of rearing the Blonde d'Aquitaine show a lower ingestion of forage (5.8 kg dry matter.100 kg -1 life weight vs. 7.5 kg dry matter.100 kg -1 life weight) and lower growth than the Charolais (1 150 g.d -1 vs. 1 400 g.d -1 ). At pasture, the activity of the animals is similar (380 minutes at pasture, 52 bites per minute for speed of ingestion). At slaughter, at the same body weight (695 kg), the Blonde d'Aquitaine have a greater weight of muscle (+ 9%, 335 kg of muscle vs. 308 kg). The Blonde d'Aquitaine have a more glycolytic muscular metabolism (1 497 μmol. min -1.g -1 vs. 1351 μmol.min -1.g -1 ), a higher proportion of fast, IIB fibers (63.6% vs. 58.8%) and less collagen (3.7 μg d'OH-prol.mg -1 of DM vs. 5.2 μg d'OH-prol.mg -1 of DM). These results show that animals of blonde d'Aquitaine breed provide a good valorisation of forage and grass and that under these breeding conditions, they produce muscles with favourable characteristics for production of tender meat. blonde d'Aquitaine / Charolais / grass / muscle fibers / collagen