Low Levels of Branched Chain Amino Acids, Eicosapentaenoic Acid and Micronutrients Are Associated with Low Muscle Mass, Strength and Function in Community-Dwelling Older Adults.

BACKGROUND: Sarcopenia, the age-related decrease in muscle mass and function can result in adverse health outcomes and subsequent loss of independence. Inadequate nutrition is an important contributor to the aetiology of sarcopenia, and dietary strategies are studied to prevent or delay this geriatric syndrome. OBJECTIVE: The present study investigated whether there is an association between biochemical nutrient status markers, muscle parameters and sarcopenia in community-dwelling older adults. DESIGN: Data from the cross-sectional Maastricht Sarcopenia study (MaSS) were used, in which skeletal muscle index (SMI), 4 meter gait speed, 5 times chair stand and handgrip strength were assessed among older adults (n=227). Sarcopenia was defined following the algorithm of the European Working Group on Sarcopenia in Older People. Fasted blood samples were analyses on amino acids levels, RBC phospholipid profile, 25-hydroxyvitamin D (25(OH)D), α-tocopherol, magnesium and homocysteine were determined in fasted blood levels. Generalized linear modelling and logistic regression were used for data analysis. RESULTS: Lower blood levels of essential amino acids (EAA), total branched-chain amino acids (BCAA) and leucine were associated with lower SMI (P<0.001), strength (P<0.001) and longer time to complete the chair stand (P<0.05), whereas no association was found for total amino acids (TAA). Lower levels of eicosapentaenoic acid (EPA), 25(OH)D and homocysteine were associated with lower muscle parameter values (P<0.05). No significant associations were found for SFA, MUFA, PUFA, n-3 and n-6 fatty acids, docosahexaenoic acid (DHA), α-tocopherol-cholesterol ratio and magnesium. Sarcopenia was more frequent among those with lower levels of leucine, BCAA, EAA, EPA, 25(OH)D and higher levels of homocysteine (P<0.05). Age and BMI were identified as relevant covariates. A robust association was only found for lower gait speed and lower 25(OH)D levels. CONCLUSION: Compromised muscle parameters are associated with low blood values of specific amino acids, fatty acids, vitamin D and high homocysteine.

Muscle, Health and Costs: A Glance at their Relationship.

OBJECTIVE: To assess the association between muscle parameters (mass, strength, physical performance) and activities of daily living (ADL), quality of life (QoL), and health care costs. DESIGN: Cross-sectional Maastricht Sarcopenia Study (MaSS). SETTING: Community-dwelling, assisted-living, residential living facility. PARTICIPANTS: 227 adults aged 65 and older. MEASUREMENTS: Muscle mass, hand grip strength and physical performance were assessed by bio-electrical impedance, JAMAR dynamometer and the Short Physical Performance Battery, respectively. Health outcomes were measured by the Groningen Activity Restriction Scale (disability in ADL) and the EQ-5D-5L (QoL). Health care costs were calculated based on health care use in the past three months. RESULTS: Muscle strength and physical performance showed a strong correlation with ADL, QoL, and health care costs (P<.01); for muscle mass no significant correlations were observed. Regression analyses showed that higher gait speed (OR 0.06, 95%CI 0.01-0.55) was associated with a lower probability of ADL disability. Furthermore, slower chair stand (OR 1.23, 95%CI 1.08-1.42), and more comorbidities (OR 1.58, 95%CI 1.23-2.02) were explanatory factors for higher ADL disability. Explanatory factors for QoL and costs were: more disability in ADL (OR 1.26, 95%CI 1.12-1.41 for QoL; B = 0.09, P<.01 for costs) and more comorbidities (OR 1.44, 95%CI 1.14-1.82 for QoL; B = 0.35, P<.01 for costs). CONCLUSION: Lower gait speed and chair stand were potential drivers of disability in ADL. Disability in ADL and comorbidities were associated with QoL and health care costs in community-dwelling older adults. Improving physical performance may be a valuable target for future intervention and research to impact health burden and costs.

Predicting falls in elderly receiving home care: the role of malnutrition and impaired mobility.

UNLABELLED: To investigate the role of malnutrition, impaired mobility and care dependency in predicting fallers in older Dutch home care clients. DESIGN: This study is a secondary analysis of data of the annual independent national prevalence measurement of care problems of Maastricht University. The design involves a cross-sectional, multicentre point prevalence measurement (malnutrition, mobility), and a 30 days incidence measurement (falls). SETTING: Dutch home care organisations. PARTICIPANTS: 2971 clients (older than 65 years) from 22 home care organizations participated. MEASUREMENTS: A standardized questionnaire was used to register amongst others data of weight, height, number and type of diseases (like for example neurologic diseases, dementia, CVA, COPD, eye/ear disorders, musculoskeletal disorders), nutritional intake, use of psychopharmaca, undesired weight loss, fall history, mobility, and care dependency. RESULTS: The study was able to show that fallers are more often malnourished than non-fallers in the univariate analysis. Most importantly the study indicated by multivariate analysis that fallers could be predicted by the risk factors immobility ((OR 2.516 95% CI 1.144-5.532), high care dependency (OR 1.684 95% CI 1.121-2.532) and malnutrition (OR 1.978 95% CI 1.340-2.920). CONCLUSION: The findings of this study stress that malnutrition, impaired mobility and care dependency are potential reversible factors related to falls. Therefore early identification and management of nutritional status, impaired mobility and care dependency are important aspects for a possible fall prevention strategy.

Dose-dependent effects of leucine supplementation on preservation of muscle mass in cancer cachectic mice.

Cancer cachexia, which is characterized by muscle wasting, is associated with increased morbidity and mortality. Because muscle protein synthesis may be increased and protein breakdown reduced by leucine supplementation, we used the C26 tumor-bearing cachectic mouse model to assess the effects of dietary supplementation with leucine on muscle weight and the markers of muscle protein breakdown (mRNA of atrogin and murf). Male CD2F1 mice were subcutaneously inoculated with tumor cells (tumor-bearing mice; TB) or were sham injected (control; C). They were fed standard diets or diets supplemented with leucine [1 gr (TB1Leu) or 8 gr (TB8Leu) supplemented leucine per kg feed]; TB and C received 8.7% Leu/g protein, TB1Leu received 9.6% Leu/g protein and TB8Leu received 14.6 Leu/g protein. After 21 days, the following were determined: body weights, plasma amino-acid concentrations, tumor size and muscle mass of the gastrocnemius (mG), tibialis anterior (mTA), extensor digitorum longus (mEDL) and soleus (mS) muscles. In tumor-bearing (TB) mice, carcass and skeletal muscle masses decreased, and levels of atrogin and murf mRNA in the mEDL increased. Muscle-mass loss was counteracted dose-dependently by leucine supplementation: relative to TB, the mass of the mG was +23% in TB8Leu, and +22% in mTA (p<0.05). However, leucine supplementation did not change atrogin and murf mRNA levels. Total plasma amino acid concentrations increased in TB, especially for taurine, lysine, arginine and alanine (p<0.05). Leucine supplementation attenuated the increase in total plasma amino-acid concentrations (p<0.05). Irrespective of changes in muscle protein breakdown markers, leucine supplementation reduced muscle wasting in tumor-bearing cachectic mice and attenuated changes in plasma amino acids.

Methods using stable isotopes to measure nitric oxide (NO) synthesis in the L-arginine/NO pathway in health and disease.

Nitric oxide (NO) is an important gaseous radical involved in many physiological processes. It is produced from the amino acid L-arginine by the action of nitric oxide synthases (NOS) in what is called the L-arginine/NO pathway. Tracking its metabolic fate in biological fluids is of particular interest as it may indicate how the human body responds in health and disease. However, due to its short life span (a few seconds) it is very difficult to accurately monitor any up- or down-regulation in body fluids in vivo. As a consequence, methods have been developed based on the measurement of the NO-derived products nitrite and nitrate or on the substrate of NO, L-arginine and its simultaneously generated product, L-citrulline. Considering only a fraction of the endogenous L-arginine pool is used for the synthesis of NO, NO-production cannot be estimated by measuring changes in the concentrations of L-arginine and/or L-citrulline alone. Instead, to estimate NO-related changes in the L-arginine and/or L-citrulline pools a form of tagging these metabolites for the NOS-mediated reaction is required. The application of stable isotopes is an elegant way to track NOS-mediated changes. The present paper is focussed on the application of various combinations of chromatography and mass spectrometry to measure isotopic enrichments resulting from the conversion of L-arginine to NO and L-citrulline in a one-to-one stoichiometry. In addition, the various aspects and principles involved in the application of stable isotopes in metabolic studies in general and the study of the activity of NOS in particular are discussed.

Effects of long-term intravenous and intragastric L-arginine intervention on jejunal motility and visceral nitric oxide production in the hyperdynamic compensated endotoxaemic pig.

Alterations in L-arginine availability and nitric oxide (NO) synthesis in the intestinal muscularis may contribute to disturbed small intestinal motility that is observed during endotoxaemia. The aim of this study was to evaluate the effect of L-arginine infusion on visceral NO production and jejunal motility in hyperdynamic compensated endotoxaemic pigs. Fasted and saline-resuscitated pigs were intravenously infused for 24 h with endotoxin (lipopolysaccharide, 50 ng kg(-1) min(-1)) or saline (n = 6). Endotoxaemic pigs received either intravenous L-arginine (n = 6, 5.3 micromol kg(-1) min(-1)) or L-alanine (isocaloric, n = 6). After 24 h, intravenous L-arginine or L-alanine infusion was continued intragastrically for 32-h in an enteral meal. During (0-24 h) and 1 day postendotoxaemia (48-56 h), jejunal motility was recorded by manometry and analysed for migrating motor complex (MMC) characteristics. Visceral NO production was measured at 24 and 48 h by 15N2-arginine-to-15N-citrulline conversion. Visceral NO production was increased during endotoxaemia and was higher in L-arginine than in L-alanine-treated pigs. One day postendotoxaemia, visceral NO synthesis was still increased in L-arginine but not in L-alanine-treated animals. Endotoxaemia shortened the MMC cycle duration and accelerated the MMC propagation velocity. Both were restored by L-arginine. Similar motility disturbances were observed one day postendotoxaemia and were also compensated by L-arginine infusion.

In vivo whole body and organ arginine metabolism during endotoxemia (sepsis) is dependent on mouse strain and gender.

Arginine metabolism involves various organs such as the kidney, the intestines, and the liver, which act together in an interorgan axis. Major pathways for arginine production are protein breakdown and de novo arginine production from citrulline; disposal of arginine is mainly used for protein synthesis or used by the enzymes arginase and nitric oxide synthase (NOS). To assess in vivo organ arginine metabolism under normal conditions and during endotoxemia we used a mouse model, and analyzed for gender and strain differences. Male and female inbred FVB and C57BL6/J mice were anesthetized and catheterized to study whole body, gut, liver, renal and muscle metabolism, using a stable isotope infusion protocol. Animals were treated with saline or lipopolysaccharide. Plasma arginine levels tended to be higher in female mice, although levels were not significantly different from male mice (P = 0.09). Although not all significantly different, whole body arginine production and arginine clearance tended to be higher in C57BL6/J mice (P < 0.1), while citrulline (P = 0.05), NO (P = 0.08), and de novo arginine (P < 0.01) production were higher in FVB mice. During endotoxemia, NO production increased in general (P < 0.05), while whole body arginine clearance increased in FVB mice, but decreased in C57BL6/J mice (P < 0.01). At the organ level, portal-drained viscera (PDV) arginine metabolism was higher in FVB than in C57BL6/J mice (P < 0.05). During endotoxemia, liver arginine metabolism decreased in general (P < 0.05), while strain differences existed for PDV, muscle, and renal arginine metabolism. In conclusion, stable isotope techniques in multicatheterized mice allow measurements of arginine metabolism on whole body and organ level. Strain and gender differences are present in arginine metabolism under physiological conditions and during endotoxemia.

Differential effects of motilin on interdigestive motility of the human gastric antrum, pylorus, small intestine and gallbladder.

Motilin was infused in this study with the aim of examining refractory characteristics for motilin stimulation of antral phase III and fasting gallbladder emptying. Moreover, interdigestive pyloric and small intestinal motility from duodenum to ileum were studied, as these may be target organs for motilin. Eight fasting, healthy male volunteers received, on separate subsequent days, repeated infusions of 13leucine-motilin (8 pmol (kg min)(-1) for 5 min) or saline at 30 min after phase IIIs in the duodenum. Interdigestive motility of the antrum, pylorus, duodenum, jejunum and ileum was measured for maximum 10 h by using a 21-lumen perfused catheter. Gallbladder motility was measured by ultrasonography. Motilin infusions induced antral phase IIIs, but only after a preceding phase III of duodenal origin. Under this condition, time-interval to phase III at the duodenal recording site was 30 +/- 13 (SEM) min after motilin, compared with 79 +/- 14 min after saline (P < 0.01), and compared with 121 +/- 13 min for motilin infusion following an antral phase III (P < 0.001). Motilin did not affect small intestinal motility or isolated pyloric pressure waves (IPPWs). However, the number of IPPWs was significantly affected by the origin of the preceding phase III, irrespective of whether motilin or saline was infused. Gallbladder volume decreased significantly within 10 min after each motilin infusion. We conclude that this study clearly demonstrates differential regional effects of motilin. Motilin initiates antral phase IIIs, but stimulation is subject to a refractory period which is clearly prolonged after a preceding antral phase III. Motilin induced gallbladder emptying, however, is not subject to a refractory state. Small intestinal phase IIIs as well as pyloric IPPWs are not affected by motilin.

Effects of motilin on human interdigestive gastrointestinal and gallbladder motility, and involvement of 5HT3 receptors.

A plasma motilin peak and a partial gallbladder emptying precede the antral phase III of the migrating motor complex (MMC). To clarify the causal relationship between these factors, we aimed to study the role of motilin in interdigestive gastrointestinal and gallbladder motility simultaneously. In addition, involvement of 5HT3 receptors in the action of motilin was studied. Eight fasting, healthy male volunteers received 13Leu-motilin or 0.9% NaCl i.v. for 30 min, in randomized order on two separate occasions, from 30 min after phase III. Seven of the eight subjects also received the 5HT3 receptor antagonist ondansetron in addition to motilin, on a third occasion. Antroduodenal motility, gallbladder volumes and plasma motilin were measured. The interval between the start of infusion and phase III was 95.0 (57.6-155.7) min for saline, 28.7 (21.0-33.2) min for motilin, and 39.3 (30.7-100.5) min for motilin + ondansetron (P < 0.05). Gallbladder volume decreased by one-third from 10 min after both motilin and motilin + ondansetron infusion (P < 0.05), and returned to baseline with duodenal passage of phase III. In two of the seven subjects phase III was absent after motilin + ondansetron, although gallbladder volume decreased and only refilled during a later spontaneous phase III. We conclude that motilin induces both partial gallbladder emptying and antral phase III. Indeed, although gallbladder emptying clearly precedes antral phase III, ondansetron only prevented phase III in some cases and had no effect on gallbladder emptying. Passage of phase III in the duodenum makes an important contribution to gallbladder refilling.

Effects of intraduodenal bile on interdigestive gastrointestinal and gallbladder motility in healthy subjects.

BACKGROUND/AIMS: The enterohepatic circulation of bile acids is related to normal inter-digestive gastrointestinal motility, with the gut peptide motilin also being involved. This study aimed to investigate the effect of intraduodenal artificial bile infusion on antroduodenal and gallbladder motility so as to further elucidate the controlling factors. METHODS: Twelve fasting, healthy male volunteers received artificial bile (80 mol% bile acids; 15 mol% phospholipids; 5 mol% cholesterol) or placebo (saline) intraduodenally for 10 min starting 30 min after the end of phase III, according to a double-blind, randomised, cross-over design. Antroduodenal motility, gallbladder volumes, and plasma motilin levels were measured. All values are means +/- SEM. RESULTS: The interval between infusion and the subsequent phase III, as well as the origin of this phase III were not significantly different between bile and saline. Antral pressure waves were significantly more frequent during and immediately after bile infusion compared with saline infusion (p < 0.05). The duration of phase I following infusion was significantly longer after bile (24.8 +/- 3.7 min) than after saline infusion (13.1 +/- 1.7 min; p < 0.05). The mean gallbladder volume tended to increase in the hours following bile infusion, but to decrease after saline infusion (p = 0.06). Plasma motilin increased after bile and saline infusion in an almost identical way. CONCLUSION: This study provides no clear evidence for a role of intraduodenal artificial bile (i.e. its main constituents) in the regulation of migrating motor complex cycling or feedback inhibition of inter-digestive gallbladder emptying.

Migrating motor complex cycle duration is determined by gastric or duodenal origin of phase III.

The migrating motor complex (MMC) shows large variations within an individual and between individuals. This study aimed to investigate, with respect to this variability, the importance of gastric or duodenal origin of phase III activity. Interdigestive 6- to 10-h stationary antroduodenal motility recordings of 19 healthy male subjects were analyzed for MMC cycle durations and duration of phases I, II, and III, all with respect to the place of origin of each phase III. Data are given for the duodenal recording site as means +/- SE. Mean MMC cycle duration was 117.3 +/- 13.9 min, regardless of the place of origin of phase III. Seventy-two phase III cycles were observed in total, 35 and 37 starting in the "antrum" and duodenum, respectively. After a phase III of "antral" origin, MMC cycle duration was 156.1 +/- 11.0 min, significantly longer than MMC cycle duration following a phase III of duodenal origin, 80.5 +/- 10.7 min (P < 0.001). Phase III duration was longer when of "antral" origin than when starting in the duodenum (7.6 +/- 0.4 and 5.3 +/- 0.4 min, respectively; P < 0.001). MMC cycle duration and duration of phases I, II, and III depend on the place of origin of phase III ("antral" or duodenal) and on the origin of the preceding phase III. This factor explains part of the MMC variability observed within individuals. Mean MMC cycle duration in healthy subjects or patients should therefore also include information on the origin of phase III.

Effects of long-term oral L-arginine on esophageal motility and gallbladder dynamics in healthy humans.

Inhibitory nitrergic neurons are known to play a role in the regulation of motility patterns of the distal esophagus, the lower esophageal sphincter (LES), and the gallbladder. Our study aim was to investigate the effects of "long-term" (i.e., prolonged) oral intake of L-arginine (L-Arg), the endogenous source for nitric oxide (NO) synthesis, on postprandial LES pressure (LESP), esophageal motility, gastroesophageal reflux, and gallbladder motility. L-Arg (30 g/day) or glycine (placebo; 13 g/day; isosmolar) was given orally to 10 healthy male volunteers for 8 days, according to a randomized, crossover design. Twenty-four-hour urinary nitrite/nitrate excretion was measured to indicate NO synthesis. Basal early postprandial LESP was lower after L-Arg ingestion (2.2 kPa) than after glycine ingestion (2.7 kPa) (P < 0.05). L-Arg abolished the physiological late postprandial rise in LESP. Transient LES relaxations were longer lasting after L-Arg ingestion (P < 0.02). Esophageal motility and reflux were not affected (not significant). Fasting and residual gallbladder volumes were greater after L-Arg ingestion (P < 0.05). Urinary nitrite/nitrate excretion was higher after L-Arg intake (P < 0.05). In conclusion, long-term oral L-Arg suppresses late postprandial LESP increase, prolongs transient LES relaxations, and increases fasting and residual gallbladder volumes. These effects may be mediated by increased NO synthesis.

Motilin induces gall bladder emptying and antral contractions in the fasted state in humans.

BACKGROUND: Animal studies have shown that motilin affects gall bladder motility. In humans, no effect has been shown, but erythromycin, a motilin receptor agonist, induces gall bladder emptying. AIMS: To explore the effect of increasing doses of exogenous motilin on gall bladder volume and antral contractility in the fasted state in humans. METHODS: After an overnight fast, eight healthy men received increasing intravenous doses of Leu13-motilin (KW-5139) or 0.9% NaCl in a double blind, randomised fashion. Gall bladder volume and antral contraction frequency were determined by ultrasonography. RESULTS: Infusion of motilin increased plasma motilin levels. Motilin induced a reduction in gall bladder volume of 8.0 (5.0)%, 17.1 (5.0)%, 18.5 (4.7)%, and 16.1 (4.9)% of baseline volume at the end of infusion of 2, 4, 8, and 16 pmol/kg/min respectively, compared with mean stable gall bladder volumes during placebo infusion (p < 0.05). Antral contraction frequency increased during motilin infusion, but not during placebo infusion (p < 0.05). CONCLUSIONS: Exogenous motilin reducted fasting gall bladder volume and increased antral contractions. After reaching maximal reduction, the gall bladder volume did not decrease further during continuous motilin infusion at higher doses and stayed at the same reduced volume. The degree of gall bladder volume reduction during motilin infusion mimicked gall bladder emptying preceding antral phase III activity of the migrating motor complex in humans. This study indicates that motilin may play a physiological role in the regulation of gall bladder emptying in the fasted state.

Disrupted bile flow affects interdigestive small bowel motility in rats.

BACKGROUND: The role of bile flow in the regulation of small bowel motility and the migrating myoelectric complex (MMC) is unclear. We aimed to study the effects of biliary diversion or obstruction on the MMC in a newly developed rat model. METHODS: In rats, myoelectrodes were implanted in the jejunum, and the proximal common bile duct (CBD) was cannulated and exteriorized at the head, enabling us to manipulate biliary flow without influencing pancreatic flow and without the need of anesthesia or additional surgery. Group A were controls without CBD cannulas. Biliary circulation was exteriorized but kept intact in group B; bile was diverted externally in group C; and the CBD was obstructed in group D. MMCs were recorded in unrestrained conditions by jejunal electromyography before and after biliary diversion or obstruction. Spontaneous recanalization of the CBD was monitored by measurement of serum bilirubin and by cholangiography. RESULTS: Exteriorization of the CBD without interruption of bile flow did not affect MMC duration (group A, 17.3 +/- 0.3 minutes [mean +/- SEM]; group B, 16.5 +/- 0.6 minutes). MMCs disappeared temporarily after CBD obstruction but not after biliary diversion. MMCs of increased duration were seen after 1 day in rats with biliary diversion or CBD obstruction (group C, 26.1 +/- 4.4 minutes; group D, 36.3 +/- 4.8 minutes [p < 0.05]). MMCs after biliary diversion or obstruction were characterized by an increased duration of phase II-like activity and decreased duration of phase I activity. CONCLUSIONS: We conclude that MMCs disappear temporarily early after CBD obstruction, but MMCs of increased duration are seen after 1 day of biliary diversion or obstruction. Thus disrupted bile flow affects interdigestive small bowel motility in rats.