scholarly journals Measuring protein breakdown rate in individual proteins in vivo

2010 ◽  
Vol 13 (5) ◽  
pp. 526-531 ◽  
Author(s):  
Lars Holm ◽  
Michael Kjaer
Keyword(s):  
Protein Breakdown ◽  
Breakdown Rate

scholarly journals Determination of steady-state protein breakdown rate in vivo by the disappearance of protein-bound tracer-labeled amino acids: a method applicable in humans

2013 ◽  
Vol 304 (8) ◽  
pp. E895-E907 ◽  
Author(s):  
Lars Holm ◽  
Bruce O'Rourke ◽  
David Ebenstein ◽  
Michael J. Toth ◽  
Rasmus Bechshoeft ◽  
...  
Keyword(s):  
Amino Acids ◽  
Steady State ◽  
Exponential Decay ◽  
Turnover Rate ◽  
Deuterium Oxide ◽  
Protein Breakdown ◽  
Breakdown Rate

A method to determine the rate of protein breakdown in individual proteins was developed and tested in rats and confirmed in humans, using administration of deuterium oxide and incorporation of the deuterium into alanine that was subsequently incorporated into body proteins. Measurement of the fractional breakdown rate of proteins was determined from the rate of disappearance of deuterated alanine from the proteins. The rate of disappearance of deuterated alanine from the proteins was calculated using an exponential decay, giving the fractional breakdown rate (FBR) of the proteins. The applicability of this protein-specific FBR approach is suitable for human in vivo experimentation. The labeling period of deuterium oxide administration is dependent on the turnover rate of the protein of interest.

N τ-Methylhistidine Excretion and Myofibrillar Protein Breakdown in Patients Receiving Intravenous or Enteral Nutrition

1980 ◽  
Vol 59 (3) ◽  
pp. 211-214 ◽  
Author(s):  
I. B. Holbrook ◽  
E. Gross ◽  
P. J. Milewski ◽  
K. Shipley ◽  
M. H. Irving
Keyword(s):  
Enteral Nutrition ◽  
Muscle Protein ◽  
Myofibrillar Protein ◽  
Protein Breakdown ◽  
Breakdown Rate ◽  
Creatinine Excretion ◽  
Non Invasive ◽  
Breakdown Rates ◽  
Invasive Measurement

1. Nτ-Methylhistidine, nitrogen and creatinine were measured in the urine of 10 volunteers on normal and meat-free diets and in 10 vegetarians, and compared with the results from the urine of eight patients with intestinal fistulae on intravenous or enteral nutrition containing no meat. The values obtained were used to calculate fractional breakdown rate of myofibrillar protein. 2. There was a significant fall in the excretion of Nτ-methylhistidine and creatinine and in apparent fractional breakdown rates after 2 days on a meat-free diet. 3. One of the patients had lower, and two of the patients had higher, fractional breakdown rates compared with the vegetarians. 4. Nτ-Methylhistidine and creatinine excretion-5-be a useful and non-invasive measurement of myofibrillar protein degradation in patients on meat-free diets. Firm conclusions cannot, however, be drawn without confirmatory, direct measurement of the breakdown rates of muscle protein in vivo.

Growth Hormone-Induced Changes in Myofibrillar Protein Breakdown in Hypopituitary Children

1983 ◽  
Vol 64 (3) ◽  
pp. 315-320 ◽  
Author(s):  
F. J. Ballard ◽  
J. L. Burgoyne ◽  
F. M. Tomas ◽  
J. L. Penfold
Keyword(s):  
Growth Hormone ◽  
Hormone Treatment ◽  
Myofibrillar Protein ◽  
The Body ◽  
Protein Breakdown ◽  
Older Children ◽  
Breakdown Rate ◽  
Fractional Rate ◽  
Excretion Rates ◽  
Induced Changes

1. Creatinine and Nτ-methylhistidine excretion rates have been measured in 13 hypopituitary children to calculate the body muscle contents and rates of myofibrillar protein breakdown. Analyses have been made during periods of growth hormone withdrawal and subsequent administration. 2. The creatinine excretion rate was lower in the hypopituitary children, indicating a lower muscle content per kg body weight. This difference persisted even in children who had received growth hormone for several years. 3. Excretion of Nτ-methylhistidine was reduced by the administration of growth hormone. 4. The fractional breakdown rate of myofibrillar protein, as calculated from the Nτ-methylhistidine to creatinine molar excretion ratio, averaged 1.76%/day in the four youngest children during growth hormone withdrawal. This was significantly higher than for control children of a similar age (P < 0.02) and was reduced to the normal rate of 1.47%/day by growth hormone administration. 5. in older children the fractional rate of myofibrillar protein degradation remained in the normal range irrespective of growth hormone treatment. 6. These results are discussed in the context of the anabolic effects of growth hormone on muscle being partly explained by its action to decrease rates of protein breakdown.

Effect of inactivity and passive stretch on protein turnover in phasic and postural rat muscles

1986 ◽  
Vol 61 (1) ◽  
pp. 173-179 ◽  
Author(s):  
P. Loughna ◽  
G. Goldspink ◽  
D. F. Goldspink
Keyword(s):  
Soleus Muscle ◽  
Muscle Length ◽  
Protein Breakdown ◽  
Fractional Rate ◽  
Hindlimb Muscles ◽  
Synthetic Rate ◽  
Suspension Model ◽  
Fast Twitch ◽  
Passive Stretch

A state of hypokinesia and hypodynamia has been induced in the hindlimb muscles of the rat (100 g) using a suspension model. The ensuing muscle atrophy was assessed by reference to muscles in fully mobile control animals, which were either fed ad libitum or fed the same lower food intake of the suspended animals. Over a total of 7 days of suspension the slow-twitch postural soleus muscle underwent a much greater atrophy than the fast-twitch phasic extensor digitorum longus. Changes with respect to the position of the suspended foot, and hence muscle length, necessitate caution in comparing the extent of the atrophy between different muscle types. After 3 days of inactivity the atrophy of the soleus muscle was explained by a 21% decrease in the fractional rate of synthesis (measured in vivo) and a 100% increase in the rate of protein breakdown. The reduction in the synthetic rate was associated with a net loss (23%) of RNA and hence muscle ribosomes. In contrast when this inactive soleus muscle was permanently stretched the RNA content (44%) and protein synthetic rate increased (59%) markedly above control values. Although protein breakdown remained elevated in this stretched muscle, the extent of the atrophy in response to hypokinesia and hypodynamia was greatly reduced.

Melt Processed Polymer Blends for Potential Regenerative Medicine Applications

2014 ◽  
Vol 679 ◽  
pp. 92-100
Author(s):  
Elaine Kenny ◽  
Declan M. Devine ◽  
Clement L. Higginbotham ◽  
Luke M. Geever
Keyword(s):  
Molecular Weight ◽  
Differential Scanning Calorimetry ◽  
Regenerative Medicine ◽  
Polyethylene Oxide ◽  
Melt Flow Index ◽  
Flow Index ◽  
Biodegradable Implants ◽  
Scanning Calorimetry ◽  
Breakdown Rate

There is an urgent and unmet requirement for biocompatible and biodegradable implants that gradually resorb when implanted in vivo. This study examines the potential of melt extruded thermoplastics polyethylene oxide (PEO) and polycaprolactone (PCL) in the area of regenerative medicine. Various ratios of PEO and PCL were melt blended and analysed in order to obtain an optimised breakdown rate. Subsequently the effect of varying the molecular weight of PCL using a constant molecular weight PEO was also examined. Samples were characterised using melt flow index (MFI), differential scanning calorimetry (DSC) and breakdown analysis. It was found that by altering both the concentrations of PEO/PCL and the molecular weight of PCL, melt viscosity, breakdown rate and thermal properties could be modulated to produce potential implant materials with a tailored breakdown rate.

Fiber-type composition of nine rat muscles. II. Relationship to protein turnover

1989 ◽  
Vol 257 (6) ◽  
pp. E828-E832 ◽  
Author(s):  
P. J. Garlick ◽  
C. A. Maltin ◽  
A. G. Baillie ◽  
M. I. Delday ◽  
D. A. Grubb
Keyword(s):  
Protein Synthesis ◽  
Regression Analysis ◽  
Protein Turnover ◽  
Fiber Type ◽  
Female Rats ◽  
Protein Breakdown ◽  
Fiber Type Composition ◽  
Type Composition ◽  
Age Regression

Rates of protein synthesis in vivo and fiber-type composition were measured in nine limb muscles of female rats at ages ranging from weaning to 1 yr. In all muscles, there was a decline in protein synthesis with increasing age, mostly as a result of a fall in the RNA content. Rates of protein breakdown and growth were determined in six muscles and these also declined with age. Regression analysis of the data for all ages showed that protein synthesis was correlated with the content of slow oxidative fibers but not with the relative proportions of fast glycolytic to fast oxidative glycolytic fibers.

Enhancement of tumor proteolysis by TNF-alpha: correlation of in vivo isotope estimates with growth

1991 ◽  
Vol 261 (1) ◽  
pp. R106-R116
Author(s):  
N. W. Istfan ◽  
P. R. Ling ◽  
G. L. Blackburn ◽  
B. R. Bistrian
Keyword(s):  
Protein Synthesis ◽  
Protein Metabolism ◽  
Whole Body ◽  
Independent Effect ◽  
Yoshida Sarcoma ◽  
Protein Breakdown ◽  
Body Protein ◽  
Breakdown Rates ◽  
Made In

To evaluate the accuracy of in vivo estimates of protein synthesis and breakdown, measurements of plasma and tissue leucine kinetics were made in rat tumor tissues at different conditions of growth by use of constant intravenous infusion of [14C]leucine. These measurements were made in Yoshida sarcoma tumors on days 10 and 13 after implantation, with and without tumor necrosis factor (TNF) infusion and on day 10 in Walker-256 carcinosarcoma. Expressed as micromoles of leucine per gram tissue, tumor protein breakdown increased (P less than 0.01) from 0.32 +/- 0.02 to 0.52 +/- 0.09 (SE) mumol/h, with progress of the Yoshida sarcoma tumor between days 10 and 13 after implantation. Similarly, TNF increased tumor proteolysis on day 10 (0.43 +/- 0.03 mumol.h-1.g-1, P less than 0.05 vs. day 10 control) but not on day 13 after implantation of the Yoshida tumor. Estimates of growth derived from the difference between protein synthesis and breakdown rates were not statistically different from those based on actual tumor volume changes in both tumor models. However, estimates of “whole body” protein metabolism (plasma leucine flux) were not affected either by tumor aging or by treatment with TNF. This study shows that in vivo estimates of tissue protein metabolism based on our [14C]leucine constant infusion model closely reflect the growth characteristic of that tissue. A cytotoxic perfusion-independent effect for intravenous TNF on growing tumor tissue is demonstrable as increased protein breakdown. Furthermore, the commonly used concept of whole body protein metabolism, derived solely from tracer dilution in plasma, is an oversimplification.

Integration of in vitro parameters by mechanistic modelling to predict recycling of microbial nitrogen in the rumen

1998 ◽  
Vol 22 ◽  
pp. 158-160
Author(s):  
J. Dijkstra ◽  
J. France ◽  
S. Tamminga
Keyword(s):  
Bacterial Protein ◽  
Protein Breakdown ◽  
Microbial Protein ◽  
Evaluation Systems ◽  
Microbial Nitrogen ◽  
Substrate Conversion ◽  
Micro Organisms ◽  
Protein Supply

In protein evaluation systems for ruminants, the microbial protein supply is calculated from the amounts of rumen degradable organic matter and nitrogen (N) using empirical equations. A variable part of the rumen synthesized microbial protein does not reach the duodenum but is recycled within the rumen (review Firkins, 1996). Since energy is required for its re-synthesis and degraded microbial protein is subject to deamination, the efficiency of substrate conversion into microbial protein in the rumen is affected by microbial recycling. Rumen protozoa have a major impact upon this recycling through engulfment of micro-organisms and autolysis. In vitro, bacterial protein breakdown is proportionately reduced by some 0·9 upon removal of protozoa (Wallace and McPherson, 1987). Defaunation of the rumen increases the efficiency of microbial protein synthesis in vivo significantly (review Jouany et al., 1988).

scholarly journals Skeletal-muscle growth and protein turnover

1975 ◽  
Vol 150 (2) ◽  
pp. 235-243 ◽  
Author(s):  
D J Millward ◽  
P J Garlick ◽  
R J C Stewart ◽  
D O Nnanyelugo ◽  
J C Waterlow
Keyword(s):  
Skeletal Muscle ◽  
Growth Rate ◽  
Protein Synthesis ◽  
Muscle Protein ◽  
Muscle Growth ◽  
Muscle Size ◽  
Synthesis Rate ◽  
Protein Breakdown ◽  
Breakdown Rate ◽  
Breakdown Rates

Because of turnover, protein synthesis and breakdown can each be involved in the regulation of the growth of tissue protein. To investigate the regulation of skeletal-muscle-protein growth we measured rates of protein synthesis and breakdown in growing rats during development on a good diet, during development on a marginally low-protein diet and during rehabilitation on a good diet after a period of severe protein deficiency. Rates of protein synthesis were measured in vivo with a constant intravenous infusion of [14C]tyrosine. The growth rate of muscle protein was measured and the rate of breakdown calculated as breakdown rate=synthesis rate-growth rate. These measurements showed that during development on a good diet there was a fall with age in the rate of protein synthesis resulting from a fall in capacity (RNA concentration) and activity (synthesis rate per unit of RNA). There was a fall with age in the breakdown rate so that the rate was highest in the weaning rats, with a half-life of 3 days. There was a direct correlation between the fractional growth and breakdown rates. During rehabilitation on the good diet, rapid growth was also accompanied by high rates of protein breakdown. During growth on the inadequate diet protein synthesis rates were lesss than in controls, but growth occurred because of decreased rates of protein breakdown. This compression was not complete, however, since ultimate muscle size was only one-half that of controls. It is suggested that increased rates of protein breakdown are a necessary accompaniment to muscle growth and may result from the way in which myofibrils proliferate.

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