Artificial beta-cell promotes positive nitrogen balance and whole body protein synthesis in insulin-dependent diabetic subjects

Nitrogen balance and the whole body protein synthesis rate were measured before, during, and after a 9.5-day spaceflight mission on the space shuttle Columbia. Protein synthesis was measured by the single-pulse [15N]glycine method. Determinations were made 56, 26, and 18 days preflight, on flight days 2 and 8, and on days 0, 6, 14, and 45 postflight. We conclude that nitrogen balance was decreased during spaceflight. The decrease in nitrogen balance was greatest on the 1st day when food intake was reduced and again toward the end of the mission. An approximately 30% increase in protein synthesis above the preflight baseline was found for flight day 8 for all 6 subjects (P < 0.05), indicating that the astronauts showed a stress response to spaceflight.

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Nitrogen balance, amino aicd flux rates and rates of whole body protein synthesis in lactating and in pregnant goats at different energy intakes

Journal of Animal Physiology and Animal Nutrition ◽

10.1111/j.1439-0396.1988.tb00180.x ◽

1988 ◽

Vol 60 (1-5) ◽

pp. 86-95 ◽

Cited By ~ 2

Author(s):

Poul Martin Riis

Keyword(s):

Protein Synthesis ◽

Nitrogen Balance ◽

Whole Body ◽

Body Protein

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Protein Metabolism in Human Neonates: Nitrogen-Balance Studies, Estimated Obligatory Losses of Nitrogen and Whole-Body Turnover of Nitrogen

Clinical Science ◽

10.1042/cs0520485 ◽

1977 ◽

Vol 52 (5) ◽

pp. 485-498 ◽

Cited By ~ 8

Author(s):

P. B. Pencharz ◽

W. P. Steffee ◽

W. Cochran ◽

N. S. Scrimshaw ◽

W. M. Rand ◽

...

Keyword(s):

Protein Synthesis ◽

Nitrogen Balance ◽

Growth And Development ◽

Term Infant ◽

Nitrogen Losses ◽

Whole Body ◽

Nitrogen Flux ◽

Body Protein ◽

Mean Values ◽

The Mean

1. Aspects of nitrogen metabolism in the human neonate were assessed in one full-term infant and six premature infants by means of nitrogen-balance measurements, estimates of obligatory nitrogen losses and determinations of whole-body nitrogen turnover. 2. Our data indicate that the mean protein requirement for maintenance is 1·1 g of protein day−1 kg−1 and that 3·8 g of protein day−1 kg−1 should be sufficient for adequate growth in healthy premature babies. 3. The mean obligatory urinary, faecal and total nitrogen losses were estimated to be 24, 106 and 145 mg day−1 kg−1 respectively. These figures are compared with published values for older infants, and the possible metabolic basis for changes in nitrogen losses during growth and development is discussed. 4. Mean values for whole-body protein synthesis and breakdown were 26·3 ± 7·0 and 23·8 ± 7·4 g of protein day−1 kg−1 respectively. Dietary nitrogen intake accounted for 6–18% of the nitrogen flux through the metabolic pool; urea excretion accounted for 2% of the nitrogen flux. 5. The net protein gain, estimated from nitrogen-balance data, accounted for 9·6% of total daily protein synthesis. 6. These results are discussed in relation to published estimates of whole-body protein synthesis and breakdown at various ages. Their possible significance in the assessment of a ‘maintenance’ requirement for protein and amino acids during the period of rapid growth and development is also considered.

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Functional impact of high protein intake on healthy elderly people

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.90536.2008 ◽

2008 ◽

Vol 295 (4) ◽

pp. E921-E928 ◽

Cited By ~ 74

Author(s):

Stephane Walrand ◽

Kevin R. Short ◽

Maureen L. Bigelow ◽

Andrew J. Sweatt ◽

Susan M. Hutson ◽

...

Keyword(s):

Protein Synthesis ◽

Older People ◽

Mitochondrial Function ◽

Nitrogen Balance ◽

Protein Intake ◽

Muscle Protein ◽

High Protein ◽

Whole Body ◽

Body Protein ◽

Healthy Elderly

Decline in muscle mass, protein synthesis, and mitochondrial function occurs with age, and amino acids are reported to enhance both muscle protein synthesis and mitochondrial function. It is unclear whether increasing dietary protein intake corrects postabsorptive muscle changes in aging. We determined whether a 10-day diet of high [HP; 3.0 g protein·kg fat-free mass (FFM)−1·day−1] vs. usual protein intake (UP; 1.5 g protein·kg FFM−1·day−1) favorably affects mitochondrial function, protein metabolism, and nitrogen balance or adversely affects insulin sensitivity and glomerular filtration rate (GFR) in 10 healthy younger (24 ± 1 yr) and 9 older (70 ± 2 yr) participants in a randomized crossover study. Net daily nitrogen balance increased equally in young and older participants, but postabsorptive catabolic state also increased, as indicated by higher whole body protein turnover and leucine oxidation with no change in protein synthesis. Maximal muscle mitochondrial ATP production rate was lower in older people, with no change occurring in diet. GFR was lower in older people, and response to HP was significantly different between the two groups, with a significant increase occurring only in younger people, thus widening the differences in GFR between the young and older participants. In conclusion, a short-term high-protein diet increased net daily nitrogen balance but increased the postabsorptive use of protein as a fuel. HP did not enhance protein synthesis or muscle mitochondrial function in either young or older participants. Additionally, widening differences in GFR between young and older patients is a potential cause of concern in using HP diet in older people.

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Diet and nitrogen metabolism during spaceflight on the shuttle

Journal of Applied Physiology ◽

10.1152/jappl.1996.81.1.82 ◽

1996 ◽

Vol 81 (1) ◽

pp. 82-97 ◽

Cited By ~ 54

Author(s):

T. P. Stein ◽

M. J. Leskiw ◽

M. D. Schluter

Keyword(s):

Protein Synthesis ◽

Dietary Intake ◽

Energy Intake ◽

Nitrogen Balance ◽

Nitrogen Retention ◽

The Body ◽

Whole Body ◽

Flight Period ◽

Flight Duration ◽

Body Protein

Human spaceflight is associated with a loss of body protein. To investigate this problem, dietary intake, nitrogen balance, the whole body protein, and fibrinogen protein synthesis rates were measured on the crews of two Spacelab Life Sciences (SLS) shuttle missions before, during, and after spaceflight. The first mission, SLS-1, lasted 9.5 days, and the second, SLS-2, lasted 15 days. The 15N-glycine method was used for the protein synthesis measurements. The following results were obtained. 1) There was a rapid decline in weight for the first 5 days and then the body weight appeared to stabilize. 2) The mean energy intake preflight was 39.0 +/- 2.5 kcal x kg-1 x day-1 (n = 10). There was a sharp drop in dietary intake on flight day 1, with recovery by the second day, and then energy intake was constant at 30.4 +/- 1.5 kcal x kg-1 x day-1 (n = 12) for the remainder of the flight period (P < 0.05). 3) Nitrogen retention was decreased during flight, with the magnitude of the decrease lessening toward the end of the mission. The daily mean nitrogen balance changed from 58 +/- 9 mg x kg-1 x day-1 (n = 9) preflight to 16 +/- 3 mg N x kg-1 x day-1; P < 0.05; n = 11) in flight, corresponding to a loss of approximately 1 kg of lean body mass over 14 days. 4) Whole body protein synthesis was increased early in flight and on recovery, as was fibrinogen synthesis. We conclude that 1) the rapid readjustment and stabilization of energy intake and the improved nitrogen retention with increasing flight duration are consistent with a rapid metabolic accommodation to the novel environment; and that 2) the increased protein turnover indicates that a metabolic stress response is an important factor in this adjustment process.

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Effect of rhGH and rhIGF-I treatment on protein utilization in elderly women

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1997.272.1.e94 ◽

1997 ◽

Vol 272 (1) ◽

pp. E94-E99 ◽

Cited By ~ 13

Author(s):

G. E. Butterfield ◽

J. Thompson ◽

M. J. Rennie ◽

R. Marcus ◽

R. L. Hintz ◽

...

Keyword(s):

Protein Synthesis ◽

Growth Factor ◽

Nitrogen Balance ◽

Elderly Women ◽

Muscle Protein ◽

Muscle Protein Synthesis ◽

Whole Body ◽

High Dose ◽

Protein Utilization ◽

Body Protein

To assess the effect of recombinant human growth hormone (rhGH) and recombinant human insulin-like growth factor I (rhIGF-I) on protein utilization, 14 women, age 66-82 yr, were invited to participate in studies of nitrogen balance (n = 14), whole body protein turnover (n = 14), and muscle protein synthesis (n = 8). They were studied both 1 wk before and during the last week of a 1-mo regimen, to which they had been randomly assigned, of either 0.025 mg rhGH/kg once daily or rhIGF-I at 0.015 (low), 0.03 (mid), or 0.06 (high) mg/kg twice daily. Nitrogen balance increased significantly after 1 wk of treatment in all groups (P < 0.05). After 1 mo, the magnitude of this effect had diminished by 50% in the rhGH group but remained elevated throughout the treatment period with all doses of rhIGF-I. Both protein synthesis and breakdown, measured by a primed constant infusion of [15N]glycine, were significantly increased with rhGH (9% and 8%, respectively), low-dose rhIGF-I (4.5% and 4%), and high-dose rhIGF-I (18% and 17%). Net synthesis was significantly increased with rhGH (48%) and high- and mid-dose rhIGF-I (27% and 196%, respectively). Muscle protein synthesis as measured by incorporation of [1-13C]leucine increased significantly with rhGH (50%) and the mid (67%) and high (57%) doses of rhIGF-I. These data show that whole body and muscle protein synthesis are responsive to growth factor stimulation in elderly women.

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Effect of dietary protein on energy metabolism including protein synthesis in the spiny lobster Sagmariasus verreauxi

Scientific Reports ◽

10.1038/s41598-021-91304-1 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Shuangyao Wang ◽

Chris G. Carter ◽

Quinn P. Fitzgibbon ◽

Basseer M. Codabaccus ◽

Gregory G. Smith

Keyword(s):

Protein Synthesis ◽

Energy Metabolism ◽

Dietary Protein ◽

Spiny Lobster ◽

Ammonia Excretion ◽

Metabolic Energy ◽

Whole Body ◽

Body Protein ◽

Energy Substrate ◽

Sagmariasus Verreauxi

AbstractThis is the first study in an aquatic ectotherm to combine a stoichiometric bioenergetic approach with an endpoint stochastic model to explore dietary macronutrient content. The combination of measuring respiratory gas (O2 and CO2) exchange, nitrogenous (ammonia and urea) excretion, specific dynamic action (SDA), metabolic energy substrate use, and whole-body protein synthesis in spiny lobster, Sagmariasus verreauxi, was examined in relation to dietary protein. Three isoenergetic feeds were formulated with varying crude protein: 40%, 50% and 60%, corresponding to CP40, CP50 and CP60 treatments, respectively. Total CO2 and ammonia excretion, SDA magnitude and coefficient, and protein synthesis in the CP60 treatment were higher compared to the CP40 treatment. These differences demonstrate dietary protein influences post-prandial energy metabolism. Metabolic use of each major energy substrate varied at different post-prandial times, indicating suitable amounts of high-quality protein with major non-protein energy-yielding nutrients, lipid and carbohydrate, are critical for lobsters. The average contribution of protein oxidation was lowest in the CP50 treatment, suggesting mechanisms underlying the most efficient retention of dietary protein and suitable dietary inclusion. This study advances understanding of how deficient and surplus dietary protein affects energy metabolism and provides approaches for fine-scale feed evaluation to support sustainable aquaculture.

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