Milk protein supplementation and the regulation of lean tissue mass in healthy community dwelling 50-70y old women and men

Population demographics demonstrate that the number of older individuals will triple to approximately 1.5 billion by 2050. Age-related sarcopenia is associated with a progressive loss of lean tissue mass (LTM), strength and function. Based on population specific data from the University of Limerick Body Composition (ULBC) study, the rate of decline in LTM is approximately 0.35-0.45% (0.14-0.26 kg) per annum after the age of 50 years. Interest has developed in the retention of LTM with advancing age to maintain functional and metabolic benefits that an appropriate LTM afford. Older populations display a blunted muscle protein synthetic response to the main anabolic stimuli, namely nutrient ingestion and mechanical loading. In the absence of mechanical loading, a potential dietary strategy to overcome anabolic resistance is the distribution of daily protein intake to equal amounts (25-30 g) over the three main eating occasions of the day. A 20-30 g, quality protein intake is deemed to provide an extracellular essential amino acid (EAA) concentration to stimulate muscle protein synthesis (MPS). Specific to the EAAs, leucine commands greatest importance acting as both a substrate and intracellular regulator of MPS. Augmentation of the nutrient effect is provided by mechanical loading, i.e. resistance exercise, an interaction that needs to be evaluated in the elderly in situ with optimal timing and quality of nutrient intake. Following in vitro evaluation of a milk-based protein nutrient formulation this thesis investigated the bioactive properties of oral ingestion of the nutrient formulation in vivo in elderly subjects. The nutrient formulation invoked a postprandial increase in circulating peak plasma EAA (1,848 ± 83 μM) and leucine (321 ± 22 μM) concentration. Parallel studies by in vivo skeletal muscle microdialysis (MD) confirmed that the extracellular tissue concentration of these key amino acids was similarly advanced. A 24 week RCT in a group of healthy 50-70y old community dwelling women and men was then conducted to explore the nutrient effect on the maintenance of LTM, measured by dual energy x-ray absorptiometry (DXA). For this RCT, isocaloric amounts of milk-based protein formulation (FORM) (0.33 g.kg-1.d-1) or maltodextrin (MALT) was added to the two smaller main meals of the day i.e. breakfast and lunch. Potential augmentation of the nutrient supplement was investigated by engagement in whole body, resistance-band exercise adapted specifically for this population (FORM + Progressive Resistance exercise Training (PRT)). The main outcome of the RCT was a differential effect of the composition of the dietary supplement on whole body lean tissue mass. A statistically significant between treatment, net effect amounting to +0.60 kg LTM was observed (-0.16 ± 0.87 kg in MALT vs. 0.44 ± 1.06 kg in FORM; P = 0.004) after 24 weeks. In a separate group, the treatment effect attributed to supplementation with milk-based protein augmented the net change in LTM by engagement in PRT (0.80 ± 1.02 kg), but not to a statistically significant extent (P = 0.60). In conclusion, a milk-based dietary supplement designed to correct habitual, sub-optimal, meal based protein intake in healthy, protein sufficient 50–70y old adults resulted in a positive effect on whole body lean tissue mass. The mechanism of action of this effect is informed by the investigation of the in vivo bioactivity of the milk-protein based supplement reported in this thesis

The effect of hydration status on the measurement of lean tissue mass by dual-energy X-ray absorptiometry

Athletes cycle between exercise and recovery. Exercise invokes changes in total body water from thermal sweating, muscle and hepatic glycogen depletion and metabolic water loss. Recovery from exercise results in rehydration, substrate repletion, and possible glycogen supercompensation. Such changes may corrupt the measurement of hydrated tissues, such as lean tissue mass (LTM), by dual-energy X-ray absorptiometry (DXA). The purpose of this study was to determine the effect of exercise and thermal dehydration and subsequent glycogen supercompensation on DXA-based measurement of body composition.Twelve active adult (18-29 years) males exercised at 70% VO2max on a cycle ergometer in a thermal environment (30 A degrees C) to induce a 2.5% reduction in body mass. Participants subsequently underwent a glycogen supercompensation phase, whereby a high carbohydrate diet (8-12 g/kg body mass/day) was consumed for a 48-h period. Whole-body DXA measurement was performed at baseline, following exercise and supercompensation.Following exercise, mean body mass decreased by -1.93 kg (95% CI -2.3, -1.5), while total LTM decreased by -1.69 kg (-2.4, -1.0). Supercompensation induced a mean body mass increase of 2.53 kg (2.0, 3.1) and a total LTM increase of 2.36 kg (1.8, 2.9). No change in total fat mass or bone mineral content was observed at any timepoint.Training regimens that typically induce dehydration and nutrition regimens that involve carbohydrate loading can result in apparent changes to LTM measurement by DXA. Accurate measurement of LTM in athletes requires strict observation of hydration and glycogen status to prevent manipulation of results

Age-group differences in the performance of selected tests of physical function and association with lower extremity strength

. Background and Purpose: It is not known whether short functional performance tests used in aging research are appropriate for use in healthy older adults. The purpose of this study was to investigate age-group differences (sixth decade vs seventh decade) in selected functional performance tests and the association between lower extremity strength and functional performance. Methods: One hundred fifty-nine (18.2% [n = 29] male) healthy older adults (mean (standard deviation) age 60.4 (5.3) years), adults were recruited from the University of Limerick Campus Community. Knee extensor (KE) peak torque (PT) was assessed from a maximal voluntary isometric contraction. Subsequently, participants completed 10-m maximal and habitual gait speed tests, 5 repetition and 30-second chair rise tests, and a 900-m gait speed test. Results and Discussion: There was no difference in 10-m gait speed between those in the sixth and seventh decades (P > .05). Compared with the sixth decade, those in the seventh decade required an extra 39 seconds to complete 900 m, an extra 0.6 seconds to complete 5 chair rises and performed 2 fewer chair rises in a 30-second time period (P < .05). All tests had a weak association with KE strength (r = 0.226-0.360; P < .05), except for 900-m gait speed that had a moderate association (r = −0.537; P < .001). Our findings suggest that gait speed tests of 10 m or less cannot detect age-related difference in functional capacity when used in healthy older adults. Conclusion: Extended physical performance tests should be used in aging research on healthy older adults

Muscle strength can better differentiate between gradations of functional performance than muscle quality in healthy 50-70 y women

OBJECTIVE: It is not known which laboratory indices of muscle mass, strength or quality can distinguish functional performance in healthy middle aged women. The aim of this study was to a) examine the association between upper leg lean tissue mass (LTM), knee extensor strength, muscle quality (strength per unit LTM) and functional performance and b) to determine the utility of tertiles of muscle strength and muscle quality to distinguish gradations of functional capacity in healthy 50 – 70y women. METHOD: Using a cross-sectional study design, one hundred and twenty eight healthy 50 – 70y women (age: 60.4 ± 5.1 years) underwent body composition assessment (dual X-ray absorptiometry) and performed a maximal voluntary isometric contraction of the knee extensors (Con-Trex Dynamometer). Functional performance was assessed using a 5 repetition and 30 second chair rise test and 900m gait speed test. RESULTS: Ordered by muscle strength or muscle quality, those in the highest tertile (T1) demonstrated greater functional performance than those in lowest tertile (T3) (P.05). Muscle strength explained a greater proportion of the variance in all functional performance measures relative to muscle quality (P<0.05). CONCLUSION: Upper leg LTM is not associated with physical performance in healthy 50 – 70y women. These results suggest strength relative to the body mass being accelerated distinguishes gradations in functional performance better than muscle quality healthy 50-70y women

A comparison of the insulinotropic and enterogastric response to ingestion of an equivalent quantity of maltodextran and whey protein

no abstract availabl

Twelve weeks' progressive resistance training combined with protein supplementation beyond habitual intakes increases upper leg lean tissue mass, muscle strength and extended gait speed in healthy older women

The age-related decline in functional capability is preceded by a reduction in muscle quality. The purpose of this study was to assess the combined effects of progressive resistance training (PRT) and protein supplementation beyond habitual intakes on upper leg lean tissue mass (LTM), muscle quality and functional capability in healthy 50–70 years women. In a single-blinded, randomized, controlled design, 57 healthy older women (age 61.1 ± 5.1 years, 1.61 ± 0.65 m, 65.3 ± 15.3 kg) consumed 0.33 g/kg body mass of a milk-based protein matrix (PRO) for 12 weeks. Of the 57 women, 29 also engaged in a PRT intervention (PRO + PRT). In comparison to the PRO group (n = 28), those in the PRO + PRT group had an increase in upper leg LTM [0.04 (95% CI -0.07 to 0.01) kg vs. 0.13 (95% CI 0.08–0.18) kg, P = 0.027], as measured by Dual-energy X-ray absorptiometry; an increase in knee extensor (KE) torque [-1.6 (95% CI -7.3 to 4.4 N m) vs. 10.2 (95% CI 4.3–15.8 N m), P = 0.007], as measured from a maximal voluntary isometric contraction (Con-Trex MJ; CMV AG); and an increase in extended gait speed [-0.01 (95% CI -0.52–0.04) m s-1 vs. 0.10 (95% CI 0.05–0.22) m s-1, P = 0.001] as measured from a maximal 900 m effort. There was no difference between groups in the time taken to complete 5 chair rises or the number of chair rises performed in 30 s (P>0.05). PRT in healthy older women ingesting a dietary protein supplement is an effective strategy to improve upper leg LTM, KE torque and extended gait speed in healthy older women

Table_1_Point of care detection of SARS-CoV-2 antibodies and neutralisation capacity—lateral flow immunoassay evaluation compared to commercial assay to inform potential role in therapeutic and surveillance practices.DOCX

IntroductionAs the COVID-19 pandemic moves towards endemic status, testing strategies are being de-escalated. A rapid and effective point of care test (POCT) assessment of SARS-CoV-2 immune responses can inform clinical decision-making and epidemiological monitoring of the disease. This cross-sectional seroprevalence study of anti-SARS-CoV-2 antibodies in Irish healthcare workers assessed how rapid anti-SARS-CoV-2 antibody testing can be compared to a standard laboratory assay, discusses its effectiveness in neutralisation assessment and its uses into the future of the pandemic.MethodsA point of care lateral flow immunoassay (LFA) detecting anti-SARS-CoV-2 spike (S)-receptor binding domain (RBD) neutralising antibodies (Healgen SARS-CoV-2 neutralising Antibody Rapid Test Cassette) was compared to the Roche Elecsys/-S anti-SARS-CoV-2 antibody assays and an in vitro surrogate neutralisation assay. A correlation between anti-spike (S), anti-nucleocapsid (N) titres, and in vitro neutralisation was also assessed.Results1,777 serology samples were tested using Roche Elecsys/-S anti-SARS-CoV-2 assays to detect total anti-N/S antibodies. 1,562 samples were tested using the POC LFA (including 50 negative controls), and 90 samples were tested using an in vitro ACE2-RBD binding inhibition surrogate neutralisation assay. The POCT demonstrated 97.7% sensitivity, 100% specificity, a positive predictive value (PPV) of 100%, and a negative predictive value (NPV) of 61% in comparison to the commercial assay. Anti-S antibody titres determined by the Roche assay stratified by the POC LFA result groups demonstrated statistically significant differences between the “Positive” and “Negative” LFA groups (p ConclusionHigh sensitivity, specificity, and PPV were demonstrated for the POC LFA for the detection of anti-S-RBD antibodies in comparison to the commercial assay. The LFA was not a reliable determinant of the neutralisation capacity of identified antibodies. POC LFA are useful tools in sero-epidemiology settings, pandemic preparedness and may act as supportive tools in treatment decisions through the rapid identification of anti-Spike antibodies.</p

Angiogenin levels and ANG genotypes: dysregulation in amyotrophic lateral sclerosis

Objective: To determine whether 5 single nucleotide polymorphisms (SNPs) associate with ALS in 3 different populations. We also assessed the contribution of genotype to angiogenin levels in plasma and CSF. Methods: Allelic association statistics were calculated for polymorphisms in the ANG gene in 859 patients and 1047 controls from Sweden, Ireland and Poland. Plasma, serum and CSF angiogenin levels were quantified and stratified according to genotypes across the ANG gene. The contribution of SNP genotypes to variance in circulating angiogenin levels was estimated in patients and controls. Results: All SNPs showed association with ALS in the Irish group. The SNP rs17114699 replicated in the Swedish cohort. No SNP associated in the Polish cohort. Age- and sex-corrected circulating angiogenin levels were significantly lower in patients than in controls (p,0.001). An allele dose-dependent regulation of angiogenin levels was observed in controls. This regulation was attenuated in the ALS cohort. A significant positive correlation between CSF plasma angiogenin levels was present in controls and abolished in ALS. Conclusions: ANG variants associate with ALS in the Irish and Swedish populations, but not in the Polish. There is evidence of dysregulation of angiogenin expression in plasma and CSF in sporadic ALS. Angiogenin expression is likely to be important in the pathogenesis of ALS