Frailty, Sarcopenia, and Malnutrition Frequently (Co-)occur in Hospitalized Older Adults:A Systematic Review and Meta-analysis

OBJECTIVES: The purpose of this systematic review and meta-analysis was to summarize the prevalence of, and association between, physical frailty or sarcopenia and malnutrition in older hospitalized adults. DESIGN: A systematic literature search was performed in 10 databases. SETTING AND PARTICIPANTS: Articles were selected that evaluated physical frailty or sarcopenia and malnutrition according to predefined criteria and cutoffs in older hospitalized patients. MEASURES: Data were pooled in a meta-analysis to evaluate the prevalence of prefrailty and frailty [together (pre-)frailty], sarcopenia, and risk of malnutrition and malnutrition [together (risk of) malnutrition], and the association between either (pre-)frailty or sarcopenia and (risk of) malnutrition. RESULTS: Forty-seven articles with 18,039 patients (55% female) were included in the systematic review, and 39 articles (8868 patients, 62% female) were eligible for the meta-analysis. Pooling 11 studies (2725 patients) revealed that 84% [95% confidence interval (CI): 77%, 91%, I2 = 98.4%] of patients were physically (pre-)frail. Pooling 15 studies (4014 patients) revealed that 37% (95% CI: 26%, 48%, I2 = 98.6%) of patients had sarcopenia. Pooling 28 studies (7256 patients) revealed a prevalence of 66% (95% CI: 58%, 73%, I2 = 98.6%) (risk of) malnutrition. Pooling 10 studies (2427 patients) revealed a high association [odds ratio (OR): 5.77 (95% CI: 3.88, 8.58), P < .0001, I2 = 42.3%] and considerable overlap (49.7%) between physical (pre-)frailty and (risk of) malnutrition. Pooling 7 studies (2506 patients) revealed a high association [OR: 4.06 (95% CI: 2.43, 6.80), P < .0001, I2 = 71.4%] and considerable overlap (41.6%) between sarcopenia and (risk of) malnutrition. CONCLUSIONS AND IMPLICATIONS: The association between and prevalence of (pre-)frailty or sarcopenia and (risk of) malnutrition in older hospitalized adults is substantial. About half of the hospitalized older adults suffer from 2 and perhaps 3 of these debilitating conditions. Therefore, standardized screening for these conditions at hospital admission is highly warranted to guide targeted nutritional and physical interventions

Postprandial muscle protein synthesis is higher after a high whey protein, leucine-enriched supplement than after a dairy-like product in healthy older people: a randomized controlled trial

BACKGROUND: Decreased ability of muscles to respond to anabolic stimuli is part of the underlying mechanism for muscle loss with aging. Previous studies suggest that substantial amounts of essential amino acids (EAA), whey protein and leucine are beneficial for stimulation of acute muscle protein synthesis in older adults. However, these studies supplied only proteins, and no bolus studies have been done with dairy products or supplements that contained also fat and carbohydrates besides proteins. The aim of this study was to evaluate whether a specifically designed nutritional supplement in older adults stimulates muscle protein synthesis acutely to a greater extent than a conventional dairy product. Moreover, the combined effect with resistance exercise was studied by using a unilateral resistance exercise protocol. METHODS: Utilizing a randomized, controlled, double blind study design, healthy older adults received a single bolus of a high whey protein, leucine-enriched supplement (EXP: 20g whey protein, 3g total leucine, 150kcal; n = 9) or an iso-caloric milk protein control (Control: 6g milk protein; n = 10), immediately after unilateral resistance exercise. Postprandial mixed muscle protein fractional synthesis rate (FSR) was measured over 4h using a tracer infusion protocol with L-[ring-(13)C(6)]-phenylalanine and regular blood and muscle sampling. RESULTS: FSR was significantly higher overall after EXP (0.0780 ± 0.0070%/h) vs Control (0.0574 ± 0.0066%/h (EMM ± SE)) (p = 0.049). No interaction between treatment and exercise was observed (p = 0.519). Higher postprandial concentrations of EAA and leucine are possible mediating factors for the FSR response, while plasma insulin increase did not dictate the FSR response. Moreover, when the protein intake from the supplements was expressed per kg leg lean mass (LLM), a significant correlation was observed with resting postprandial FSR (r = 0.48, P = 0.038). CONCLUSIONS: Ingestion of a high whey protein, leucine-enriched supplement resulted in a larger overall postprandial muscle protein synthesis rate in healthy older subjects compared with a conventional dairy product. This acute effect is promising for long-term effects on parameters of muscle mass, strength and function in sarcopenic older people, which requires further study. TRIAL REGISTRATION: This trial is registered in the Dutch Trial Register under number NTR1823

Ex-vivo changes in amino acid concentrations from blood stored at room temperature or on ice: implications for arginine and taurine measurements

Background: Determination of the plasma concentrations of arginine and other amino acids is important for understanding pathophysiology, immunopathology and nutritional supplementation in human disease. Delays in processing of blood samples cause a change in amino acid concentrations, but this has not been precisely quantified. We aimed to describe the concentration time profile of twenty-two amino acids in blood from healthy volunteers, stored at room temperature or on ice.Methods: Venous blood was taken from six healthy volunteers and stored at room temperature or in an ice slurry. Plasma was separated at six time points over 24 hours and amino acid levels were determined by high-performance liquid chromatography.Results: Median plasma arginine concentrations decreased rapidly at room temperature, with a 6% decrease at 30 minutes, 25% decrease at 2 hours and 43% decrease at 24 hours. Plasma ornithine increased exponentially over the same period. Plasma arginine was stable in blood stored on ice, with a &lt; 10% change over 24 hours. Plasma taurine increased by 100% over 24 hours, and this change was not prevented by ice. Most other amino acids increased over time at room temperature but not on ice.Conclusion: Plasma arginine concentrations in stored blood fall rapidly at room temperature, but remain stable on ice for at least 24 hours. Blood samples taken for the determination of plasma amino acid concentrations either should be placed immediately on ice or processed within 30 minutes of collection

An Observational Cohort Study of the Kynurenine to Tryptophan Ratio in Sepsis: Association with Impaired Immune and Microvascular Function

Both endothelial and immune dysfunction contribute to the high mortality rate in human sepsis, but the underlying mechanisms are unclear. In response to infection, interferon-γ activates indoleamine 2,3-dioxygenase (IDO) which metabolizes the essential amino acid tryptophan to the toxic metabolite kynurenine. IDO can be expressed in endothelial cells, hepatocytes and mononuclear leukocytes, all of which contribute to sepsis pathophysiology. Increased IDO activity (measured by the kynurenine to tryptophan [KT] ratio in plasma) causes T-cell apoptosis, vasodilation and nitric oxide synthase inhibition. We hypothesized that IDO activity in sepsis would be related to plasma interferon-γ, interleukin-10, T cell lymphopenia and impairment of microvascular reactivity, a measure of endothelial nitric oxide bioavailability. In an observational cohort study of 80 sepsis patients (50 severe and 30 non-severe) and 40 hospital controls, we determined the relationship between IDO activity (plasma KT ratio) and selected plasma cytokines, sepsis severity, nitric oxide-dependent microvascular reactivity and lymphocyte subsets in sepsis. Plasma amino acids were measured by high performance liquid chromatography and microvascular reactivity by peripheral arterial tonometry. The plasma KT ratio was increased in sepsis (median 141 [IQR 64–235]) compared to controls (36 [28–52]); p<0.0001), and correlated with plasma interferon-γ and interleukin-10, and inversely with total lymphocyte count, CD8+ and CD4+ T-lymphocytes, systolic blood pressure and microvascular reactivity. In response to treatment of severe sepsis, the median KT ratio decreased from 162 [IQR 100–286] on day 0 to 89 [65–139] by day 7; p = 0.0006) and this decrease in KT ratio correlated with a decrease in the Sequential Organ Failure Assessment score (p<0.0001). IDO-mediated tryptophan catabolism is associated with dysregulated immune responses and impaired microvascular reactivity in sepsis and may link these two fundamental processes in sepsis pathophysiology

Arginine and sepsis: a question of the right balance?

CommentEditorialResearch Support, N.I.H. ExtramuralSCOPUS: ed.jinfo:eu-repo/semantics/publishe

NOS3 is involved in the increased protein and arginine metabolic response in muscle during early endotoxemia in mice

Sepsis is a severe catabolic condition. The loss of skeletal muscle protein mass is characterized by enhanced release of the amino acids glutamine and arginine, which (in)directly affects interorgan arginine and the related nitric oxide (NO) synthesis. To establish whether changes in muscle amino acid and protein kinetics are regulated by NO synthesized by nitric oxide synthase-2 or -3 (NOS2 or NOS3), we studied C57BL6/J wild-type (WT), NOS2-deficient (NOS2-/-), and NOS3-deficient (NOS3-/-) mice under control (unstimulated) and lipopolysaccharide (LPS)-treated conditions. Muscle amino acid metabolism was studied across the hindquarter by infusing the stable isotopes L-[ring-2H5]phenylalanine, L-[ring-2H2]tyrosine, L-[guanidino-15N2]arginine, and L-[ureido-13C,2H2]citrulline. Muscle blood flow was measured using radioactive p-aminohippuric acid dilution. Under baseline conditions, muscle blood flow was halved in NOS2-/- mice (P < 0.1), with simultaneous reductions in muscle glutamine, glycine, alanine, arginine release and glutamic acid, citrulline, valine, and leucine uptake (P < 0.1). After LPS treatment, (net) muscle protein synthesis increased in WT and NOS2-/- mice [LPS vs. control: 13 +/- 3 vs. 8 +/- 1 (SE) nmol.10 g(-1).min(-1) (WT), 18 +/- 5 vs. 7 +/- 2 nmol.10 g(-1).min(-1) (NOS2-/-); P < 0.05 for LPS vs. control]. This response was absent in NOS3-/- mice (LPS vs. control: 11 +/- 4 vs. 10 +/- 2 nmol.10 g(-1).min(-1)). In agreement, the increase in muscle arginine turnover after LPS was also absent in NOS3-/- mice. In conclusion, disruption of the NOS2 gene compromises muscle glutamine release and muscle blood flow in control mice, but had only minor effects after LPS. NOS3 activity is crucial for the increase in muscle arginine and protein turnover during early endotoxemi

The role of NOS2 and NOS3 in renal protein and arginine metabolism during early endotoxemia in mice

Previously, we observed an enhanced renal protein synthesis and increased de novo arginine production in the early response to endotoxemia in wild-type Swiss mice (Hallemeesch MM, Soeters PB, and Deutz NE. Am J Physiol Renal Physiol 282: F316-F323, 2002). To establish whether these changes are regulated by nitric oxide (NO) synthesized by NO synthase isoforms NOS2 and NOS3, we studied C57BL6/J wild-type (WT), NOS2-deficient (NOS2(-/-)), and NOS3-deficient (NOS3(-/-)) mice under baseline (unstimulated) and LPS-treated conditions. The metabolism of renal protein, amino acid, and arginine was studied at the whole body level and across the kidney by infusing the stable isotopes l-[phenyl-(2)H(5)]phenylalanine, l-[phenyl-(2)H(2)]tyrosine, l-guanidino-[(15)N(2)]arginine, and l-[ureido-(13)C,(2)H(2)]citrulline. Renal blood flow was measured using radioactive PAH extraction. Under baseline conditions, renal blood flow was significantly reduced in NOS2(-/-) mice (0.29 +/- 0.01 vs. 0.48 +/- 0.07 ml.10 g body wt(-1).min(-1) in WT) (P < 0.05), and de novo arginine production was lower in NOS2(-/-) mice. After LPS challenge, renal protein turnover and arginine production increased in all three groups (P < 0.05), even though renal de novo arginine synthesis did not increase. The expected increase in renal citrulline production and disposal after LPS was not observed in NOS2(-/-) mice (P = 0.06). Collectively, these data show that NOS2 is constitutively expressed in the kidney and remarkably functional as it affects renal blood flow and de novo arginine production under baseline conditions and is important for the increase in renal citrulline turnover during endotoxemia. NOS3, in contrast, appears less important for renal metabolism. The increase in renal protein turnover during endotoxemia does not depend on NOS2 or NOS3 activit