Citrulline enhances myofibrillar constituents expression of skeletal muscle and induces a switch in muscle energy metabolism in malnourished aged rats.

Citrulline (Cit) actions on muscle metabolism remain unclear. Those latter were investigated using a proteomic approach on Tibialis muscles from male Sprague-Dawley rats. At 23 months of age, rats were either fed ad libitum (AL group) or subjected to dietary restriction for 12 weeks. At the end of the restriction period, one group of rats was euthanized (R group) and two groups were refed for one week with a standard diet supplemented with nonessential amino acids group or Cit (CIT group). Results of the proteomic approach were validated using targeted Western blot analysis and assessment of gene expression of the related genes. Maximal activities of the key enzymes involved in mitochondrial functioning were also determined. Cit supplementation results in a significant increase in the protein expression of the main myofibrillar constituents and of a few enzymes involved in glycogenolysis and glycolysis (CIT vs. AL and R, p < 0.05). Conversely, the expression of oxidative enzymes from Krebs cycle and mitochondrial respiratory chain was significantly decreased (CIT vs. AL, p < 0.05). However, maximal activities of key enzymes of mitochondrial metabolism were not significantly affected, except for complex 1 which presented an increased activity (CIT vs. AL and R, p < 0.05). In conclusion, Cit supplementation increases expression of the main myofibrillar proteins and seems to induce a switch in muscle energy metabolism, from aerobia toward anaerobia.

Four-week administration of an energy and protein dense oral nutritional supplement improves micronutrient concentrations but does not completely correct deficiencies in institutionalized malnourished older adults.

Introduction: Poor food intake is common among elderly living in nursing homes, leading to micronutrient deficiency (MD). There are no recommendations for the management of MD in malnourished older adults. Methods: We conducted a single arm, open-label, multicenter interventional study in institutionalized malnourished older adults to describe the effect of a 4-week daily energy and protein dense oral nutritional supplementation (ONS, 600 kcal, 30 g protein per unit) containing 50% of the recommended daily micronutrient intake on micronutrient status. Plasma concentrations of vitamins (A, B9, B12, C, E), magnesium (Mg), selenium (Se) and zinc (Zn), and erythrocyte vitamin B9 were measured at baseline and after 4 weeks. Results: Forty-six participants completed the study (age 87.4 ± 6.6). At baseline, the most frequent MD were Se (48%), Zn (35%), Mg (24%) and vitamin C (24%). Plasma concentrations of vitamins B9, B12, C and E, Mg, Se and Zn significantly increased and the proportion of subjects with at least one MD decreased (p = 0.006). However, after 4 weeks, 40% of subjects still had at least one MD. Discussion: ONS consumption improved micronutrient status but did not correct MD in all participants. Our data suggest that the prescription of vitamin, mineral and trace element supplementation should be considered in institutionalized malnourished older adults in addition to high energy and high protein ONS.

Fruit and vegetable intake in older hospitalized patients.

PURPOSE OF REVIEW: Regular intake of fruit and vegetables (F&Vs) has been widely recommended to improve the health of the population. Observational studies show a preventive effect of long-term consumption of adequate nutrients on cancer, diabetes, dementia and other age-related diseases. However, the short-term impact of F&V intake in more specific populations has been under-researched. In the hospital setting, economic choices and logistic problems result in poor quality of food in general, and particularly in fresh F&Vs. As hospital geriatricians, we set out to address the issue of F&V intake in elderly hospitalized patients, for whom we felt F&Vs might be beneficial in association with a protein and energy-dense diet. RECENT FINDINGS: In the community and in nursing homes, F&V consumption is associated with better overall food intake and improved quality of life in older patients. SUMMARY: General inspection of the literature suggests that F&Vs may be beneficial to elderly hospitalized patients, but no clinical studies have been conducted. There is a need to address the question of the impact of improved quality and quantity of F&Vs on quality of life, total food intake and constipation, particularly in hospitalized elderly patients who often stay in hospital for long periods. Positive results might help to promote F&V consumption in diverse populations, with the objective of improving eating pleasure for better health.

Leucine and citrulline modulate muscle function in malnourished aged rats.

Protein energy malnutrition in the elderly causes preferential loss of muscle mass which is associated with poor functional states. Leucine and citrulline are able to stimulate muscle protein synthesis in aged rats but no study has been undertaken to evaluate their effect on muscle function. Sprague-Dawley male rats aged 23 months were used in the experiment. Part of them were subjected to a dietary restriction for 12 weeks and then assigned to four groups: a group was euthanized (restricted group), and the others were refed for 1 week with either a leucine-, a citrulline-supplemented diet, or a standard diet. The other rats were fed ad libitum. Muscle mass and motor activity significantly increased during the refeeding with either leucine or citrulline (respectively, +51 and +37% for muscle mass, P < 0.05). The improvement of muscle mass and of motor activity induced by leucine and citrulline was highly associated with that of maximal tetanic isometric force (r = 0.769, P < 0.0001; r = 0.389, P < 0.05, respectively) but only leucine improved maximal tetanic isometric force (+101%, P < 0.05). In conclusion, this is the first study to demonstrate the ability of two amino acids (leucine and citrulline) to modulate muscle function.

Combined effect of citrulline and lactoserum on amino acid availability in aged rats.

OBJECTIVE: Age-associated sarcopenia is due to anabolic resistance to feeding. Muscle protein synthesis is improved by fast proteins (e.g., lactoserum), which increase peripheral amino acid (AA) bioavailability more rapidly than slow proteins (e.g., casein), and by citrulline. Citrulline, which limits splanchnic sequestration of AA, may more effectively increase peripheral AA bioavailability when combined with lactoserum than with casein when administered as an oral nutritional protein supplement. METHODS: In this study, 25 fasted aged rats received a single gavage administration of lactoserum or casein 0.4 g/kg, alone or with citrulline 0.4 g/kg, and AA pharmacokinetics, glucose, insulin, triglycerides, and insulin-like growth factor 1 (IGF1) were monitored for 4 h. At 4 h, muscle protein and AA contents and protein synthesis activation were measured. RESULTS: While lactoserum was associated with higher AA availability, citrulline exerts only limited effects on the plasma profile of AAs from the two proteins. Maximum plasma citrulline was reached earlier with casein (T90 min) than with lactoserum (T120 min). A protein x citrulline interaction was observed for some plasma and muscle AA levels with a significant activation of mechanistic target of rapamycin complex 1 (mTORC1) signaling suggesting higher anabolism with the combination of citrulline and lactoserum. Lower plasma and muscle AA levels with citrulline and lactoserum compared to lactoserum alone suggest a greater AA utilization in a context of muscle anabolic signaling activation. CONCLUSION: Provision of a citrulline-lactoserum combination as a nutritional supplement could therefore be beneficial in terms of muscle protein balance and prevention of sarcopenia. Further studies are warranted to evaluate the efficacy of this combination.

[Utility of soluble transferrin receptor measurement for early diagnostic of iron deficiency in elderly hospitalized patients]. / Intérêt du dosage du récepteur soluble de la transferrine dans le diagnostic biologique précoce du déficit martial chez les patients âgés hospitalisés.

Diagnosis of iron deficiency is not easily performed in inflammatory situation as usually encountered in elderly hospitalized patients (>70 years old). At first, we determined serum soluble receptor transferrin (RsTf), RsTf/serum ferritin ratio (RsTf-F index) and biochemical and haematological values used to evaluate iron status, in iron-depleted subjects (ferritinemia≤50 µg/L) (group 2) (n=22, 82±7 years) or not (group 1, reference group) (n=18, 82±6 years), without inflammatory diseases. Relevance of the biological parameters to diagnose iron deficiency was evaluated (ROC curve) and a cut-off value of RsTf-F (>1.85) was established. Then, we selected 60 patients (group 3) suspect of iron deficiency as previously validated with an inflammatory syndrome (CRP>12 mg/L). Almost all patients (95%) presented at least one risk factor of iron deficiency (anticoagulant drugs, nutritional or gastrointestinal diseases). In group 3, index RsTf-F values were increased (RsTf-F: 2.69±0.82 versus group 1: 1.25±0.34, p<0.05), in anemic patients (women Hb<120 g/L, men Hb<130 g/L) (n=42) and in non-anemic patients (n=18) (respectively RsTf-F: 2.84±0.87 versus 2.35±0.58, p<0.05). Thus, in elderly patients with inflammatory disorders, RsTf-F index could suspect iron deficiency before appearance of biological anemia.

Impact of 3-week citrulline supplementation on postprandial protein metabolism in malnourished older patients: The Ciproage randomized controlled trial.

BACKGROUND: Citrulline (CIT), is not extracted by the splanchnic area, can stimulate muscle protein synthesis and could potentially find clinical applications in conditions involving low amino acid (AA) intake, such as in malnourished older subjects. OBJECTIVE: Our purpose was to research the effects of CIT supplementation on protein metabolism in particular on non-oxidative leucine disposal (NOLD, primary endpoint), and splanchnic extraction of amino acids in malnourished older patients. DESIGN: This prospective randomized multicenter study determined whole-body and liver protein synthesis, splanchnic protein metabolism and appendicular skeletal muscle mass (ASMM) in 24 malnourished older patients [80-92 years; 18 women and 6 men] in inpatient rehabilitation units. All received an oral dose of 10 g of CIT or an equimolar mixture of six non-essential amino acids (NEAAs), as isonitrogenous placebo, for 3 weeks. RESULTS: NOLD and albumin fractional synthesis rates were not different between the NEAA and CIT groups. Splanchnic extraction of dietary amino acid tended to decrease (p = 0.09) in the CIT group (45.2%) compared with the NEAA group (60.3%). Total differences in AA and NEAA area under the curves between fed-state and postabsorptive-state were significantly higher in the CIT than in the NEAA group. There were no significant differences for body mass index, fat mass (FM), lean mass (LM) or ASMM in the whole population except for a tendential decrease in FM for the citrulline group (p = 0.089). Compared with Day 1, lean mass and ASMM significantly increased (respectively p = 0.016 and p = 0.018) at Day 20 in CIT-treated women (mean respective increase of 1.7 kg and 1.1 kg), and fat mass significantly decreased (p = 0.001) at Day 20 in CIT-group women (mean decrease of 1.3 kg). CONCLUSIONS: Our results demonstrate that CIT supplementation has no effect on whole-body protein synthesis or liver protein synthesis in malnourished older subjects. However, CIT supplementation was associated with a higher systemic AA availability. In the subgroup of women, CIT supplementation increased LM and ASMM, and decreased FM.

Determination of serum albumin, analytical challenges: a French multicenter study.

Among the biological markers of morbidity and mortality, albumin holds a key place in the range of criteria used by the High Authority for Health (HAS) for the assessment of malnutrition and the coding of information system medicalization program (PMSI). If the principle of quantification methods have not changed in recent years, the dispersion of external evaluations of the quality (EEQ) data shows that the standardization using the certified reference material (CRM) 470 is not optimal. The aim of this multicenter study involving 7 sites, conducted by a working group of the French Society of Clinical Biology (SFBC), was to assess whether the albuminemia values depend on the analytical system used. The albumin from plasma (n=30) and serum (n=8) pools was quantified by 5 different methods [bromocresol green (VBC) and bromocresol purple (PBC) colorimetry, immunoturbidimetry (IT), immunonephelometry (IN) and capillary electrophoresis (CE)] using 12 analyzers. Bland and Altman's test evaluated the difference between the results obtained by the different methods. For example, a difference as high as 13 g/L was observed for the same sample between the methods (p <0.001) in the concentration range of 30 to 35 g/L. The VBC overestimates albumin across the range of values tested compared to PBC (p <0.05). PBC method gives similar results to IN for values lower than 40 g/L. For IT methods, one of the technical/analyzer tandem underestimates the albumin values inducing a difference of performance between the immunoprecipitation methods (IT vs IN, p <0.05). Although, the albumin results are related to the technical/analyzer tandem used. This variability is usually not taken into account by the clinician. Thus, clinicians and biologists have to be aware and have to check, depending on the method used, the albumin thresholds identified as risk factors for complications related to malnutrition and PMSI coding.

Geriatric Nutritional Risk Index: a new index for evaluating at-risk elderly medical patients.

BACKGROUND: Patients at risk of malnutrition and related morbidity and mortality can be identified with the Nutritional Risk Index (NRI). However, this index remains limited for elderly patients because of difficulties in establishing their normal weight. OBJECTIVE: Therefore, we replaced the usual weight in this formula by ideal weight according to the Lorentz formula (WLo), creating a new index called the Geriatric Nutritional Risk Index (GNRI). DESIGN: First, a prospective study enrolled 181 hospitalized elderly patients. Nutritional status [albumin, prealbumin, and body mass index (BMI)] and GNRI were assessed. GNRI correlated with a severity score taking into account complications (bedsores or infections) and 6-mo mortality. Second, the GNRI was measured prospectively in 2474 patients admitted to a geriatric rehabilitation care unit over a 3-y period. RESULTS: The severity score correlated with albumin and GNRI but not with BMI or weight:WLo. Risk of mortality (odds ratio) and risk of complications were, respectively, 29 (95% CI: 5.2, 161.4) and 4.4 (95% CI: 1.3, 14.9) for major nutrition-related risk (GNRI: <82), 6.6 (95% CI: 1.3, 33.0), 4.9 (95% CI: 1.9, 12.5) for moderate nutrition-related risk (GNRI: 82 to <92), and 5.6 (95% CI: 1.2, 26.6) and 3.3 (95% CI: 1.4, 8.0) for a low nutrition-related risk (GNRI: 92 to < or =98). Accordingly, 12.2%, 31.4%, 29.4%, and 27.0% of the 2474 patients had major, moderate, low, and no nutrition-related risk, respectively. CONCLUSION: GNRI is a simple and accurate tool for predicting the risk of morbidity and mortality in hospitalized elderly patients and should be recorded systematically on admission.

Citrulline stimulates muscle protein synthesis in the post-absorptive state in healthy people fed a low-protein diet - A pilot study.

BACKGROUND & AIMS: Amino acid (AA) availability is critical to maintain protein homeostasis and reduced protein intake causes a decline in protein synthesis. Citrulline, an amino acid metabolite, has been reported to stimulate muscle protein synthesis in malnourished rats. METHODS: To determine whether citrulline stimulates muscle protein synthesis in healthy adults while on a low-protein diet, we studied 8 healthy participants twice in a cross-over study design. Following a 3-days of low-protein intake, either citrulline or a non-essential AA mixture (NEAA) was given orally as small boluses over the course of 8 h. [ring-(13)C6] phenylalanine and [(15)N] tyrosine were administered as tracers to assess protein metabolism. Fractional synthesis rates (FSR) of muscle proteins were measured using phenylalanine enrichment in muscle tissue fluid as the precursor pool. RESULTS: FSR of mixed muscle protein was higher during the administration of citrulline than during NEAA (NEAA: 0.049 ± 0.005; citrulline: 0.060 ± 0.006; P = 0.03), while muscle mitochondrial protein FSR and whole-body protein turnover were not different between the studies. Citrulline administration increased arginine and ornithine plasma concentrations without any effect on glucose, insulin, C-peptide, and IGF-1 levels. Citrulline administration did not promote mitochondria protein synthesis, transcripts, or citrate synthesis. CONCLUSIONS: Citrulline ingestion enhances mixed muscle protein synthesis in healthy participants on 3-day low-protein intake. This anabolic action of citrulline appears to be independent of insulin action and may offer potential clinical application in conditions involving low amino acid intake.

Effect of aging on liver functions-an experimental study in a perfused rat liver model.

BACKGROUND: Aging is associated with marked changes in the physiology of many organs. Aging of the liver has been little studied and findings are inconclusive. The purpose of this work was to determine the effect of aging on transport and metabolic functions of the liver as assessed by extraction ratio of indocyanine green (ICG) and urea flux respectively. Bile flow was also recorded. As ICG is removed exclusively by the liver without bioconversion, its clearance reflects hepatic functional mass. METHODS: Livers from adult (3-month old) or old (24-month old) rats were perfused in a recirculating system for 90 min. At time 30 min, a bolus of 0.125 mg of indocyanine green was introduced in the perfusion buffer. At least every 10 minutes, the perfusion buffer was sampled for the measurements of ICG and urea. Bile flow was closely monitored throughout the experiment. RESULTS: Extraction ratio of ICG was increased in livers from old rats (9.49 +/- 2.84 vs 3.70 +/- 1.56% of ICG extracted), whereas urea flux was diminished (0.33 +/- 0.06 vs 1.33 +/- 0.65 micromol/min/% of ICG extracted) and bile flow was unchanged (4.03 +/- 1.02 vs 3.57 +/- 1.34 microl/min). CONCLUSIONS: Aging does not affect the different functions of the liver in the same way. It increases hepatocellular uptake function, but decreases the metabolic function of hepatocytes and does not change excretion function. These discrepancies are likely to be of some importance in the study of drug metabolism and action, and so we suggest that results should be corrected for ICG extraction.

Long-lasting improved amino acid bioavailability associated with protein pulse feeding in hospitalized elderly patients: a randomized controlled trial.

OBJECTIVE: Aging is associated with a blunted anabolic response to dietary intake, possibly related to a decrease in systemically available amino acids (AAs), which in turn may stem from increased splanchnic AA metabolism. Splanchnic sequestration can be saturated by pulse feeding (80% of daily protein intake in a single meal), enabling increased protein synthesis. The aim of this study was to explore whether protein pulse feeding increased postprandial AA concentrations, and if so whether this increase persisted after 6 wk of dietary treatment. METHODS: This prospective randomized study enrolled 66 elderly malnourished or at-risk patients in an inpatient rehabilitation unit. All were given a controlled diet for 6 wk. In a spread diet (SD) group (n = 36), dietary protein was spread over the four daily meals. In a pulse diet (PD) group (n = 30), 72% of dietary protein (averaging 1.31 g/kg body weight daily) was consumed in one meal at noon. The patients were evaluated on day 1 and at 6 wk for plasma postprandial (five times from 0 to +180 min) AA concentrations (expressed as area under the curve above baseline). RESULTS: Protein pulse feeding was more efficient than protein spread feeding at increasing plasma postprandial AA concentrations, notably of essential AAs. This increased postprandial AA bioavailability was maintained after 6 wk. CONCLUSIONS: This study demonstrates that increased postprandial AA bioavailability induced by protein pulse feeding persists after 6 wk (i.e., that there is no metabolic adaptation blunting AA bioavailability).

Consequences of age-related splanchnic sequestration of leucine on interorgan glutamine metabolism in old rats.

Dietary leucine (Leu) serves as a nitrogen donor for de novo glutamine (Gln) synthesis in muscle. However, aging is characterized by an increase in the splanchnic extraction of Leu (SPELeu), i.e., splanchnic sequestration (SSLeu), which may affect muscle Gln metabolism and its subsequent homeostasis at the whole-body level. The aim of the work was to assess the effect of age-related SSLeu on Gln metabolism in the muscle, gut, liver, kidney, and Gln exchanges among these organs during fed conditions. Young-adult (3-mo-old) or aged (24-mo-old), male Sprague-Dawley rats were studied during fed condition [infusion of amino acids (AA) into the duodenum from time 0 min (T0) to T60] under anesthesia. L-[5-(15)N]Gln and L[1-(13)C]Leu were infused into the jugular vein and L-[5,5,5-(2)H3]Leu into the duodenum. At T60, blood samples were taken from carotid artery, portal vein, hepatic vein, renal vein, and inferior vena cava for tracer-tracee ratio and AA level measurements. SSLeu was observed in old rats and was negatively correlated with muscle Gln production (r = -0.501, P < 0.01). In addition, reduced Gln muscle release in old rats was accompanied by reduced Gln uptake by the gut and kidney. However, net Gln balance across organs was not different between young adult and old rats. During fed conditions in old rats, muscle Gln production and release are reduced in relation to the observed, increased SPELeu and reduced renal and intestinal Gln uptake to maintain whole-body Gln homeostasis. Our results demonstrate the existence of an age-related change of interorgan Gln metabolism, which may be, in part, driven by SSLeu.

Citrulline: from metabolism to therapeutic use.

Citrulline possesses a highly specific metabolism that bypasses splanchnic extraction because it is not used by the intestine or taken up by the liver. The administration of citrulline may be used to deliver available nitrogen for protein homeostasis in peripheral tissues and as an arginine precursor synthesized de novo in the kidneys and endothelial and immune cells. Fresh research has shown that citrulline is efficiently transported across the intestinal luminal membrane by a set of transporters belonging to the B°,⁺, L, and b°,⁺ systems. Several pharmacokinetic studies have confirmed that citrulline is efficiently absorbed when administered orally. Oral citrulline could be used to deliver arginine to the systemic circulation or as a protein anabolic agent in specific clinical situations, because recent data have suggested that citrulline, although not a component of proteins, stimulates protein synthesis in skeletal muscle through the mammalian target of rapamycin signaling pathway. Hence, citrulline could play a pivotal role in maintaining protein homeostasis and is a promising pharmaconutrient in nutritional support strategies for malnourished patients, especially in aging and sarcopenia.

Impact of protein pulse feeding on lean mass in malnourished and at-risk hospitalized elderly patients: a randomized controlled trial.

BACKGROUND & AIMS: Aging is associated with a blunted anabolic response to dietary intake, possibly related to a decrease in systemically available amino acids (AAs), which in turn may stem from increased splanchnic AA metabolism. This splanchnic sequestration can be saturated by pulse feeding (80% of daily protein intake in a single meal), enabling increased protein synthesis. This study aimed to evaluate the efficacy of a new nutritional strategy, termed protein pulse feeding. METHODS: This prospective randomized study (ClinicalTrials.gov registration number NCT00135590) enrolled 66 elderly malnourished or at-risk patients in an inpatient rehabilitation unit. All were given a controlled diet for 6 weeks. In a spread diet (SD) group (n = 36), dietary protein was spread over the four daily meals. In a pulse diet (PD) group (n = 30), 72% of dietary protein (1.31 g/kg weight/d on average) was consumed in one meal at noon. The patients were evaluated at admission and at 6 weeks for body composition [lean mass (LM), appendicular skeletal muscle mass (ASMM), and body cell mass (BCM) indices, measured by X-ray absorptiometry combined with bioelectrical impedance analysis] (primary outcome), hand grip strength, and activities of daily living (ADL) score. RESULTS: Protein pulse feeding was significantly more efficacious than protein spread feeding in improving LM index (mean changes from baseline for PD group: +0.38 kg/m(2); 95% confidence interval (CI), [0; 0.60]; for SD group: -0.21 kg/m(2); 95% CI, [-0.61; 0.20]; p = 0.005 between the two groups), ASMM index (+0.21 kg/m(2); 95% CI, [0; 0.34] and -0.11 kg/m(2); 95% CI, [-0.20; 0.09]; p = 0.022), BCM index (+0.44 kg/m(2); 95% CI, [0.08; 0.52] and -0.04 kg/m(2); 95% CI, [-0.09; 0.10]; p = 0.004). There was no significant effect for hand-grip strength or ADL score. CONCLUSIONS: This study demonstrates for the first time that protein pulse feeding has a positive, clinically relevant effect on lean mass in malnourished and at-risk hospitalized elderly patients.

Ethyl glucuronide for detecting alcohol lapses in patients with an alcohol use disorder.

Urine ethyl glucuronide (EtG) was screened in 75 patients during a hospital-based treatment for an alcohol use disorder. During follow-up, EtG was detected in 35 (14.6%) of the 239 urine samples. Positive screens were found in 22 patients (29%), of whom nine were outpatients (39.1% of all outpatients) and 13 inpatients (25.0% of all inpatients). Of the 22 patients with positive EtG, five (22%) also gave a positive breath alcohol test and 10 (45.5%) reported recent alcohol consumption; 12 (54.5%) gave a negative breath alcohol test and declared no alcohol lapse. Ethyl glucuronide has been found useful in detecting covered lapses.

Evidence that albumin is not a suitable marker of body composition-related nutritional status in elderly patients.

OBJECTIVE: Serum albumin has long been used in clinical practice as a marker of protein-energy undernutrition, but very few studies have focused on its relation with dual-energy X-ray absorptiometry-assessed lean mass measurements, which is the current reference method in routine for body composition-related nutritional status. Serum albumin concentration is also affected by non-nutrition-related factors, and there is published evidence on the relation between serum albumin concentration and morbidity/mortality in the elderly. This study was designed to examine the relationship between serum albumin and lean mass and nutrition-related risk of morbidity/mortality in geriatric patients. Our objective was to clarify whether serum albumin in geriatric patients is a marker of body composition-related nutritional status, risk of morbidity/mortality, neither, or both. METHODS: This prospective study enrolled 125 elderly patients hospitalized in a rehabilitation unit [83.8 (SD 7.7) y]. Subjects were evaluated for serum albumin concentration and nutritional status at admission [body mass index, lean mass, appendicular skeletal muscle mass index, and body cell mass index (calculated as the ratio of the mass to the square of the height), evaluated by dual-energy X-ray absorptiometry combined with bioelectrical impedance analysis]. Outcome scores were assessed 6 mo later, taking into account complications (pressure ulcers and/or infections) and 6-mo mortality. RESULTS: Serum albumin concentration was not correlated with the lean mass, appendicular skeletal muscle mass, or body cell mass indexes. Serum albumin concentration was, however, correlated with outcome score (r = 0.22, P = 0.02). CONCLUSION: This study clearly demonstrates that albumin is not suitable as a marker of body composition in elderly patients.

Features, causes and consequences of splanchnic sequestration of amino acid in old rats.

RATIONALE: In elderly subjects, splanchnic extraction of amino acids (AA) increases during meals in a process known as splanchnic sequestration of amino acids (SSAA). This process potentially contributes to the age-related progressive decline in muscle mass via reduced peripheral availability of dietary AA. SSAA mechanisms are unknown but may involve an increased net utilization of ingested AA in the splanchnic area. OBJECTIVES: Using stable isotope methodology in fed adult and old rats to provide insight into age-related SSAA using three hypotheses: 1) an increase in protein synthesis in the gut and/or the liver, 2) an increase in AA oxidation related to an increased ureagenesis, and 3) Kupffer cell (KC) activation consequently to age-related low-grade inflammation. FINDINGS: Splanchnic extraction of Leu (SPELeu) was doubled in old rats compared to adult rats and was not changed after KC inactivation. No age-related effects on gut and liver protein synthesis were observed, but urea synthesis was lower in old rats and negatively correlated to liver Arg utilization. Net whole-body protein synthesis and arterial AA levels were lower in old rats and correlated negatively with SPELeu. CONCLUSION: SSAA is not the consequence of age-related alterations in ureagenesis, gut or liver protein synthesis or of KC activity. However, SSAA may be related to reduced net whole-body protein synthesis and consequently to the reduced lean body mass that occurs during aging.