Leucine metabolism across the gastrointestinal tract of sheep infected with Trichostrongylus colubriformis

1998 ◽  
Vol 1998 ◽  
pp. 1-1 ◽  
Author(s):  
Feng Yu ◽  
L.A. Bruce ◽  
R.L. Coop ◽  
J.C. MacRae
Keyword(s):  
Immune Response ◽  
Protein Synthesis ◽  
Gastrointestinal Tract ◽  
Protein Metabolism ◽  
Farm Animals ◽  
Tracer Kinetics ◽  
Trichostrongylus Colubriformis ◽  
Initial Infection ◽  
Leucine Metabolism ◽  
Isotope Tracer

In previous studies where sheep were subjected to experimental subclinical Trichostrongylus colubriformis infections, protein metabolism was seriously impaired during both the initial infection (5-7 weeks at early dosing) and the subsequent immune response (11-13 weeks of dosing) periods (see MacRae, 1993). Symonds and Jones (1983) reported that T. colubriformis infection increased the rates of protein synthesis in the small and large intestines of guinea pigs by 24 and 70% respectively, however there are no equivalent data in farm animals. In the present study trans-organ catheterisation procedures have been coupled with mass isotope tracer kinetics to examine leucine metabolism across the gastrointestinal (g.i.) tract of lambs subjected to subclinical T. colubriformis infection.

Leucine metabolism across the gastrointestinal tract of sheep infected with Trichostrongylus colubriformis

1998 ◽  
Vol 1998 ◽  
pp. 1-1
Author(s):  
Feng Yu ◽  
L.A. Bruce ◽  
R.L. Coop ◽  
J.C. MacRae
Keyword(s):  
Immune Response ◽  
Protein Synthesis ◽  
Gastrointestinal Tract ◽  
Protein Metabolism ◽  
Farm Animals ◽  
Tracer Kinetics ◽  
Trichostrongylus Colubriformis ◽  
Initial Infection ◽  
Leucine Metabolism ◽  
Isotope Tracer

In previous studies where sheep were subjected to experimental subclinical Trichostrongylus colubriformis infections, protein metabolism was seriously impaired during both the initial infection (5-7 weeks at early dosing) and the subsequent immune response (11-13 weeks of dosing) periods (see MacRae, 1993). Symonds and Jones (1983) reported that T. colubriformis infection increased the rates of protein synthesis in the small and large intestines of guinea pigs by 24 and 70% respectively, however there are no equivalent data in farm animals. In the present study trans-organ catheterisation procedures have been coupled with mass isotope tracer kinetics to examine leucine metabolism across the gastrointestinal (g.i.) tract of lambs subjected to subclinical T. colubriformis infection.

In vivo leucine oxidation in the gastrointestinal tract of lambs infected with nematode parasite Trichostrongylus colubriformis

1999 ◽  
Vol 1999 ◽  
pp. 107-107
Author(s):  
Feng Yu ◽  
L.A. Bruce ◽  
R.L. Coop ◽  
F Jackson ◽  
J.C. MacRae
Keyword(s):  
Gastrointestinal Tract ◽  
Tracer Kinetics ◽  
Isotope Tracer ◽  
Major Consequence ◽  
Nematode Parasites ◽  
Arterial Blood ◽  
First Pass Metabolism ◽  
First Pass ◽  
Pass Metabolism

One major consequence of the presence of the nematode parasites in the gastrointestinal tract (GIT) of ruminants appears to be an elevated flow of endogenous N component from the small intestine, leading to adverse changes in host productivity (MacRae, 1993). However, many of these aspects have remained speculative because of a lack of appropriate methodology to quantify the influence of parasites on GIT protein metabolism. In the present study oxidation of leucine sequestrated from arterial blood and digesta-derived leucine during “first pass” metabolism in the GIT of lambs subjected to subclinical T. colubriformis infection were quantified directly, using trans-organ catheterisation procedures coupled with stable isotope tracer kinetics.

Ovine fetal protein metabolism during decreased glucose delivery

1993 ◽  
Vol 265 (4) ◽  
pp. E525-E531 ◽  
Author(s):  
J. R. Milley
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Protein Metabolism ◽  
Protein Breakdown ◽  
Leucine Metabolism ◽  
Before And After ◽  
Endogenous Substrate ◽  
Endogenous Substrates ◽  
Ovine Fetal ◽  
Glucose Availability

During decreased fetal glucose delivery, endogenous substrates increasingly support metabolic rate. If oxidation of fetal amino acid stores (i.e., protein) is to provide such substrate, either protein synthesis must decrease or protein breakdown must increase. Both of these changes would diminish fetal protein accretion, an important component of fetal growth. This study was performed, therefore, to find if decreased glucose delivery alters fetal leucine metabolism. Catheters were placed in six sheep fetuses under maternal general anesthesia, and, after 6 days recovery, fetal leucine metabolism was measured by infusion of [1-14C]leucine before and after fetal glucose delivery was decreased by infusing insulin to the ewe. Later (2 days) the experiment was repeated in reverse order. Decreased fetal glucose delivery was associated with a 19% decrease in the rate of fetal leucine disposal (P < 0.001), a 42% decrease in the rate of exogenous leucine uptake (P < 0.01), and no change in the rate of fetal leucine decarboxylation. The use of leucine for protein synthesis by the fetus fell by 23% (P < 0.001), whereas the rate of protein breakdown did not change. Consequently, during decreased fetal glucose delivery, leucine accretion into fetal proteins was 28% (P < 0.02) of the control rate. In summary, fetal oxidation of amino acids derived from increased protein breakdown is not the source of endogenous substrate needed by the fetus with restricted glucose availability. Fetal protein synthesis did decrease, however, diminishing the accretion of leucine into protein.

scholarly journals Effect of insulin on hind-limb and whole-body leucine and protein metabolism in fed and fasted lambs

1987 ◽  
Vol 58 (3) ◽  
pp. 437-452 ◽  
Author(s):  
V. H. Oddy ◽  
D. B. Lindsay ◽  
P. J. Barker ◽  
A. J. Northrop
Keyword(s):  
Protein Synthesis ◽  
Protein Metabolism ◽  
Hind Limb ◽  
Whole Body ◽  
Limb Muscle ◽  
Body Protein ◽  
Leucine Metabolism ◽  
Hind Limb Muscle ◽  
Protein Synthesis And Degradation ◽  
Synthesis And Degradation

1. A combination of isotope-dilution and arterio-venous difference techniques was used to determine rates of leucine metabolism and protein synthesis and degradation in a hind-limb preparation (predominantly muscle) and the whole body of eight lambs fed on milk to appetite and eight lambs fasted from 24 to 48 h.2. Compared with fed lambs, fasted lambs showed decreased rates of protein synthesis in both whole body and hind-limb, and in hind-limb muscle, elevated rates of protein degradation.3. The effects of two rates of insulin infusion on whole-body and hind-limb-muscle leucine metabolism, and in turn on protein metabolism, were determined. Insulin had no significant effect on leucine flux or oxidation (and hence protein synthesis and degradation) in whole-body or hind-limb muscle of fed lambs. In fasted lambs insulin progressively reduced arterial leucine concentration and whole-body leucine flux and oxidation, indicating a reduction in both protein synthesis and degradation. Insulin reduced the rate of leucine efflux from hind-limb muscle, which was followed by a reduction in leucine uptake. Insulin increased hind-limb-muscle glucose uptake in both fed and fasted lambs.4. On the basis that hind-limb muscle was representative of skeletal muscle in general, we estimated that muscle accounted for the same percentage (about 27) of whole-body protein synthesis in both fed and fasted lambs. This percentage was unaffected by infusion of insulin, although the absolute rates differed in fed and fasted lambs.

Vitamin A: dietologist’s position

2020 ◽  
pp. 49-57
Author(s):  
S. V. Orlova ◽  
E. A. Nikitina ◽  
L. I. Karushina ◽  
Yu. A. Pigaryova ◽  
O. E. Pronina
Keyword(s):  
Immune Response ◽  
Urinary Tract ◽  
Gastrointestinal Tract ◽  
Vitamin A ◽  
Developed Countries ◽  
Therapeutic Practice ◽  
The Past ◽  
Increased Risk ◽  
Mucous Membranes

Vitamin A (retinol) is one of the key elements for regulating the immune response and controls the division and differentiation of epithelial cells of the mucous membranes of the bronchopulmonary system, gastrointestinal tract, urinary tract, eyes, etc. Its significance in the context of the COVID‑19 pandemic is difficult to overestimate. However, a number of studies conducted in the past have associated the additional intake of vitamin A with an increased risk of developing cancer, as a result of which vitamin A was practically excluded from therapeutic practice in developed countries. Our review highlights the role of vitamin A in maintaining human health and the latest data on its effect on the development mechanisms of somatic pathology.

The history of anabolic steroids and a review of clinical experience with anabolic steroids

1985 ◽  
Vol 110 (3_Suppla) ◽  
pp. S11-S18 ◽  
Author(s):  
H. Kopera
Keyword(s):  
Protein Synthesis ◽  
Protein Metabolism ◽  
Anabolic Steroids ◽  
Muscular Activity ◽  
Living Cells ◽  
Cellular Protein ◽  
Complex Compounds ◽  
The Body ◽  
Anabolic Effect ◽  
Vital Functions

Metabolism is the term employed to embrace the various physical and chemical processes occurring within the tissues upon which the growth and heat production of the body depend and from which the energy for muscular activity, for the maintenance of vital activity and for the maintenance of vital functions is derived (Best & Taylor 1950). The destructive processes by which complex substances are converted by living cells into more simple compounds are called catabolism. Anabolism denotes the constructive processes by which simple substances are converted by living cells into more complex compounds, especially into living matter. Catabolism and anabolism are part of all metabolic processes, the carbohydrate, fat and protein metabolism. The term anabolic refers only to substances that exert an anabolic effect on protein metabolism and are unlikely to cause adverse androgenic effects. They shift the equilibrium between protein synthesis and degradation in the body as a whole in the direction of synthesis, either by promoting protein synthesis or reducing its breakdown. The protein anabolic effect of anabolic steroids is not restricted to single organs but is the result of stimulated biosynthesis of cellular protein in the whole organism.

scholarly journals Comprehensive assessment of post-prandial protein handling by the application of intrinsically labelled protein in vivo in human subjects

2021 ◽  
pp. 1-9
Author(s):  
Jorn Trommelen ◽  
Andrew M. Holwerda ◽  
Philippe J. M. Pinckaers ◽  
Luc J. C. van Loon
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Stable Isotope ◽  
Dietary Protein ◽  
Protein Metabolism ◽  
Muscle Protein ◽  
Human Subjects ◽  
Whole Body ◽  
Body Protein

All human tissues are in a constant state of remodelling, regulated by the balance between tissue protein synthesis and breakdown rates. It has been well-established that protein ingestion stimulates skeletal muscle and whole-body protein synthesis. Stable isotope-labelled amino acid methodologies are commonly applied to assess the various aspects of protein metabolism in vivo in human subjects. However, to achieve a more comprehensive assessment of post-prandial protein handling in vivo in human subjects, intravenous stable isotope-labelled amino acid infusions can be combined with the ingestion of intrinsically labelled protein and the collection of blood and muscle tissue samples. The combined application of ingesting intrinsically labelled protein with continuous intravenous stable isotope-labelled amino acid infusion allows the simultaneous assessment of protein digestion and amino acid absorption kinetics (e.g. release of dietary protein-derived amino acids into the circulation), whole-body protein metabolism (whole-body protein synthesis, breakdown and oxidation rates and net protein balance) and skeletal muscle metabolism (muscle protein fractional synthesis rates and dietary protein-derived amino acid incorporation into muscle protein). The purpose of this review is to provide an overview of the various aspects of post-prandial protein handling and metabolism with a focus on insights obtained from studies that have applied intrinsically labelled protein under a variety of conditions in different populations.

scholarly journals Effect of long-term refeeding on protein metabolism in patients with cirrhosis of the liver

1997 ◽  
Vol 77 (2) ◽  
pp. 197-212 ◽  
Author(s):  
Jens Kondrup ◽  
Klaus Nielsen ◽  
Anders Juul
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Protein Degradation ◽  
Protein Metabolism ◽  
Cirrhosis Of The Liver ◽  
N Balance ◽  
Whole Body ◽  
Protein Requirement ◽  
Protein Utilization ◽  
Igf I

Patients with cirrhosis of the liver require an increased amount of protein to achieve N balance. However, the utilization of protein with increased protein intake, i.e. the slope from regression analysis of N balance v. intake, is highly efficient (Nielsen et al. 1995). In the present study, protein requirement and protein utilization were investigated further by measuring protein synthesis and degradation. In two separate studies, five or six patients with cirrhosis of the liver were refed on a balanced diet for an average of 2 or 4 weeks. Protein and energy intakes were doubled in both studies. Initial and final whole-body protein metabolism was measured in the fed state by primed continous [15N]glycine infusion. Refeeding caused a statistically significant increase of about 30% in protein synthesis in both studies while protein degradation was only slightly affected. The increase in protein synthesis was associated with significant increases in plasma concentrations of total amino acids (25%), leucine (58%), isoleucine (82%), valine (72%), proline (48%) and triiodothyronine (27%) while insulin, growth hormone, insulin-like growth factor (IGF)-I and IGF-binding protein-3 were not changed significantly. The results indicate that the efficient protein utilization is due to increased protein synthesis, rather than decreased protein degradation, and suggest that increases in plasma amino acids may be responsible for the increased protein synthesis. A comparison of the patients who had a normal protein requirement with the patients who had an increased protein requirement suggests that the increased protein requirement is due to a primary increase in protein degradation. It is speculated that this is due to low levels of IGF-I secondary to impaired liver function, since initial plasma concentration of IGF-I was about 25% of control values and remained low during refeeding.

Sign in / Sign up

Export Citation Format

Share Document