Bovine Milk Extracellular Vesicles (EVs) Modification Elicits Skeletal Muscle Growth in Rats.

The current study investigated how bovine milk extracellular vesicles (EVs) affected rotarod performance and biomarkers of skeletal muscle physiology in young, growing rats. Twenty-eight-day Fisher 344 rats were provided an AIN-93G-based diet for 4 weeks that either remained unadulterated [EVs and RNA-sufficient (ERS; = 12)] or was sonicated [EVs and RNA-depleted (ERD; = 12)]. Prior to (PRE) and on the last day of the intervention (POST), animals were tested for maximal rotarod performance.

Inhibition of jejunal protein synthesis and breakdown in -induced sepsis pig model.

Maintenance of gut integrity has long been recognized as crucial for survival in sepsis, but alterations in protein metabolism have not previously been documented. Therefore, in the present study, we measured in a -induced porcine sepsis model fractional protein synthesis (FSR) and breakdown rates (FBR) in jejunal mucosa in a fasted, conscious state. FSR was measured by the incorporation rate of stable tracer amino acid (l-[-C]phenylalanine) into tissue protein.

Essential amino acid-enriched meal replacement promotes superior net protein balance in older, overweight adults.

Background & Aims: Older individuals are susceptible to the loss of muscle and accumulation of fat. To address this problem, we have compared protein kinetics following consumption of an essential amino acid (EAA)-enriched meal replacement (EMR) to consumption of a high-protein meal replacement beverage (Bariatric Advantage, BA) using stable isotope methodology.

Methods: Eight older (67 ± 2), obese (35 ± 2 kg/m) female and male participants completed two studies using a randomized, crossover design in which they ingested each meal replacement.

SIRT2 gene has a classic SRE element, is a downstream target of serum response factor and is likely activated during serum stimulation.

The sirtuin proteins are an evolutionarily conserved family of NAD+-dependent deacetylases that regulate various cellular functions. Among the seven sirtuins, SIRT2 is predominantly found in the cytoplasm, and is present in a wide range of tissues. Recent studies indicate that SIRT2 plays an important role in metabolic homeostasis.

Weight Loss Strategies in the Elderly: A Clinical Conundrum.

The age-related concomitant loss of skeletal muscle and accumulation of excess adipose tissue have been commonly referred to as sarcopenic obesity. While weight loss may help mitigate the metabolic abnormalities linked to obesity, low fitness levels and muscle atrophy complicate the effectiveness of lifestyle interventions. Because of low levels of compliance, suboptimal economic efficiency, and low functional capacity, there has been no consensus on optimal therapy.

Severe negative energy balance during 21 d at high altitude decreases fat-free mass regardless of dietary protein intake: a randomized controlled trial.

In this 2-phase randomized controlled study, we examined whether consuming a higher-protein (HP) diet would attenuate fat-free mass (FFM) loss during energy deficit (ED) at high altitude (HA) in 17 healthy males (mean ± sd: 23 ± 6 yr; 82 ± 14 kg). During phase 1 at sea level (SL, 55 m), participants consumed a eucaloric diet providing standard protein (SP; 1.0 g protein/kg,) for 21 d.

Quality of meal protein determines anabolic response in older adults.

Background & Aims: It has been demonstrated that the relative content and profile of essential amino acids (EAA) play a determining role for stimulation of muscle protein synthesis (MPS) following intake of pure EAA or protein alone.

Methods: To test if this also holds in the context of mixed meals at both whole body and muscle levels, twelve older subjects (57-74 yrs) received primed continuous infusion of L-[ring-H]phenylalanine and L-[ring-H]tyrosine over a 9-h experimental period to determine whole body protein kinetics and MPS in the fasted state and following consumption of egg-based (EGG) or cereal-based (CEREAL) isocaloric and isonitrogenous breakfast. A standardized lunch, primarily consisting of beef protein was also consumed by each group.

Update on maximal anabolic response to dietary protein.

The anabolic response to dietary protein can be defined as the difference between protein synthesis and breakdown, or the net protein balance, in response to ingestion of protein alone or a mixed meal containing protein. Others have concluded that a maximal anabolic response can be achieved with ingestion of 20-35 g of a high quality protein, leading to the formulation of a popular concept that the maximal anabolic response can be achieved by distributing the total protein intake evenly throughout the day, rather than eating a majority of dietary protein with dinner. However, this concept was based entirely on the measurement of muscle protein synthesis and thus ignored the potential contributions of suppression of protein breakdown to the anabolic response, as well as the possibility that tissues and organs other than muscle may also play a role in the anabolic response.

Short term elevation in dietary protein intake does not worsen insulin resistance or lipids in older adults with metabolic syndrome: a randomized-controlled trial.

Background: There is a great deal of controversy as to whether higher protein intake improves or worsens insulin sensitivity in humans. The purpose of the study was to determine the influence of a short-term elevation in dietary protein on hepatic and peripheral insulin sensitivity in twelve older subjects (51-70 yrs) with metabolic syndrome.

Methods: Individuals were randomly assigned to one of the dietary groups: recommended protein intake (RPI, 10% of daily calorie intake) or elevated protein intake (EPI, 20% of daily calorie intake) for 4 weeks.

Effects of β-hydroxy-β-methylbutyrate on skeletal muscle mitochondrial content and dynamics, and lipids after 10 days of bed rest in older adults.

Loss of muscle mass during periods of disuse likely has negative health consequences for older adults. We have previously shown that β-hydroxy-β-methylbutyrate (HMB) supplementation during 10 days of strict bed rest (BR) attenuates the loss of lean mass in older adults. To elucidate potential molecular mechanisms of HMB effects on muscle during BR and resistance training rehabilitation (RT), we examined mediators of skeletal muscle mitochondrial dynamics, autophagy and atrophy, and intramyocellular lipids.

Characteristics of a Pseudomonas aeruginosa induced porcine sepsis model for multi-organ metabolic flux measurements.

Survival of sepsis is related to loss of muscle mass. Therefore, it is imperative to further define and understand the basic alterations in nutrient metabolism in order to improve targeted sepsis nutritional therapies. We developed and evaluated a controlled hyperdynamic severe sepsis pig model that can be used for in vivo multi-organ metabolic studies in a conscious state.

Supplementing an energy adequate, higher protein diet with protein does not enhance fat-free mass restoration after short-term severe negative energy balance.

Negative energy balance during military operations can be severe and result in significant reductions in fat-free mass (FFM). Consuming supplemental high-quality protein following such military operations may accelerate restoration of FFM. Body composition (dual-energy X-ray absorptiometry) and whole body protein turnover (single-pool [N]alanine method) were determined before (PRE) and after 7 days (POST) of severe negative energy balance during military training in 63 male US Marines (means ± SD, 25 ± 3 yr, 84 ± 9 kg).

Protein intake distribution pattern does not affect anabolic response, lean body mass, muscle strength or function over 8 weeks in older adults: A randomized-controlled trial.

Background & Aims: In our recent acute metabolic study, we found no differences in the anabolic response to differing patterns of dietary protein intake. To confirm this in a chronic study, we investigated the effects of protein distribution pattern on functional outcomes and protein kinetics in older adults over 8 weeks.

Methods: To determine chronic effects of protein intake pattern at 1.

Phenylalanine isotope pulse method to measure effect of sepsis on protein breakdown and membrane transport in the pig.

The primed-continuous (PC) phenylalanine (Phe) stable isotope infusion methodology is often used as a proxy for measuring whole body protein breakdown (WbPB) in sepsis. It is unclear if WbPB data obtained by an easy-to-use single IV Phe isotope pulse administration (PULSE) are comparable to those by PC. Compartmental modeling with PULSE could provide us more insight in WbPB in sepsis.

Protein Consumption and the Elderly: What Is the Optimal Level of Intake?

Maintaining independence, quality of life, and health is crucial for elderly adults. One of the major threats to living independently is the loss of muscle mass, strength, and function that progressively occurs with aging, known as sarcopenia. Several studies have identified protein (especially the essential amino acids) as a key nutrient for muscle health in elderly adults.

Applications of stable, nonradioactive isotope tracers in in vivo human metabolic research.

The human body is in a constant state of turnover, that is, being synthesized, broken down and/or converted to different compounds. The dynamic nature of in vivo kinetics of human metabolism at rest and in stressed conditions such as exercise and pathophysiological conditions such as diabetes and cancer can be quantitatively assessed with stable, nonradioactive isotope tracers in conjunction with gas or liquid chromatography mass spectrometry and modeling. Although measurements of metabolite concentrations have been useful as general indicators of one's health status, critical information on in vivo kinetics of metabolites such as rates of production, appearance or disappearance of metabolites are not provided.

The anabolic response to a meal containing different amounts of protein is not limited by the maximal stimulation of protein synthesis in healthy young adults.

We have determined whole body protein kinetics, i.e., protein synthesis (PS), breakdown (PB), and net balance (NB) in human subjects in the fasted state and following ingestion of ~40 g [moderate protein (MP)], which has been reported to maximize the protein synthetic response or ~70 g [higher protein (HP)] protein, more representative of the amount of protein in the dinner of an average American diet.

Acute ingestion of citrulline stimulates nitric oxide synthesis but does not increase blood flow in healthy young and older adults with heart failure.

To determine if age-associated vascular dysfunction in older adults with heart failure (HF) is due to insufficient synthesis of nitric oxide (NO), we performed two separate studies: 1) a kinetic study with a stable isotope tracer method to determine in vivo kinetics of NO metabolism, and 2) a vascular function study using a plethysmography method to determine reactive hyperemic forearm blood flow (RH-FBF) in older and young adults in the fasted state and in response to citrulline ingestion. In the fasted state, NO synthesis (per kg body wt) was ∼ 50% lower in older vs. young adults and was related to a decreased rate of appearance of the NO precursor arginine.

Elevated oxygen consumption rate in response to acute low-glucose stress: Metformin restores rate to normal level.

Cardiovascular disease (CVD) continues to be the leading cause of mortality among all age demographics in the United States, with the highest occurrence in populations aged 65 and older. Glucose levels, particularly hyperglycemia, are associated with the premature onset of age-related diseases including CVD. A major challenge in the treatment of elderly patients with chronically elevated blood glucose is the frequency of hypoglycemic episodes.

Update on protein intake: importance of milk proteins for health status of the elderly.

Loss of lean body mass that occurs with aging is the primary endpoint with which sarcopenia is defined. Furthermore, loss of muscle mass is central to the development of many adverse health issues in the elderly. Consequently, the response of lean body mass to nutritional interventions, particularly to dietary protein, has been a commonly measured endpoint.

Exploration of the protein requirement during weight loss in obese older adults.

Rationale: Currently there is no consensus on protein requirements for obese older adults during weight loss. Here we explore the potential use of a new method for assessment of protein requirements based on changes in appendicular muscle mass during weight loss.

Methods: 60 obese older adults were subjected to 13 wk weight loss program, including hypocaloric diet and resistance training.

Quantity of dietary protein intake, but not pattern of intake, affects net protein balance primarily through differences in protein synthesis in older adults.

To examine whole body protein turnover and muscle protein fractional synthesis rate (MPS) following ingestions of protein in mixed meals at two doses of protein and two intake patterns, 20 healthy older adult subjects (52-75 yr) participated in one of four groups in a randomized clinical trial: a level of protein intake of 0.8 g (1RDA) or 1.5 g·kg(-1)·day(-1) (∼2RDA) with uneven (U: 15/20/65%) or even distribution (E: 33/33/33%) patterns of intake for breakfast, lunch, and dinner over the day (1RDA-U, 1RDA-E, 2RDA-U, or 2RDA-E).

Gerontological nursing leadership in the Advancing Excellence Campaign: moving interdisciplinary collaboration forward.

Nursing was not a part of the coalition of multiple nursing home stakeholders at the roll out of the Advancing Excellence Campaign (AEC). In January 2007, several nurse organizations proactively approached the AEC leadership, were welcomed and immediately began to volunteer for leadership positions such as committee chairs and conference coordinators. This paper presents an exemplar of how a proactive stance, even when not initially included, allowed nurses to secure chairs at the decision making table of this quality campaign and contribute to improved resident outcomes.

Increased protein intake in military special operations.

Special operations are so designated for the specialized military missions they address. As a result, special operations present some unique metabolic challenges. In particular, soldiers often operate in a negative energy balance in stressful and demanding conditions with little opportunity for rest or recovery.