scholarly journals In vivo threonine oxidation in growing pigs fed on diets with graded levels of threonine

1996 ◽  
Vol 75 (6) ◽  
pp. 825-837 ◽  
Author(s):  
N. Le Floc'h ◽  
C. Obled ◽  
B. Sève
Keyword(s):  
Specific Radioactivity ◽  
Vena Cava ◽  
Live Weight ◽  
Growing Pigs ◽  
Whole Body ◽  
Constant Infusion ◽  
Balanced Diet ◽  
Liver And Pancreas ◽  
Venous Plasma

Threonine oxidation to glycine was investigated in vivo in twelve growing pigs (27·4 kg live weight) fed on one of the following three diets with graded levels of threonine supply: a low-threonine diet (LT), a control well-balanced diet (C) or a high-threonine diet (HT), during 10h constant infusion of L-[1-13C]threonine and [2-3H]glycine in the cranial vena cava and [l-14C]glycine in the portal vein.13C-threonine and glycine enrichments and [3H]glycine and [14C]glycine specific radioactivities (SR) were determined at plateau in peripheral venous plasma, liver and pancreas. Glycine praduction rates calculated from plasma [2-3H]glycine or [1-14C]glycine SR gave similar values suggesting that [l-14C]glycine SR could be used in order to estimate whole-body glycine flux. The high pancreas [1-13C]glycine enrichment provided evidence that the pancreas may be, with the liver, a major site of threonine oxidation to glycine. Moreover, the present findings suggest that threonine transport into the Liver could be the limiting step of threonine oxidation in this tissue when dietary threonine supply is low. Total threonine oxidation to glycine, calculated from plasma values of enrichment and specific radioactivity, was low and constant when the estimated absorbed threonine was lower than 4 g/d and increased for higher amounts of absorbed threonine.

scholarly journals Estimation of rate of protein synthesis by constant infusion of labelled amino acids in pigs

1978 ◽  
Vol 40 (2) ◽  
pp. 243-252 ◽  
Author(s):  
O. Simon ◽  
R. Münchmeyer ◽  
H. Bergner ◽  
Teresa Zebrowska ◽  
Lucyna Buraczewska
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Daily Intake ◽  
Specific Radioactivity ◽  
Growing Pigs ◽  
Constant Infusion ◽  
Fractional Rate ◽  
Liver And Pancreas ◽  
Infusion Method ◽  
Plasma Leucine

1. The fractional synthetic rates of tissue proteins were studied in growing pigs using the constant-infusion technique of tracer-labelled amino acids ([14C]leucine and [14C]lysine) and the mathetmatical model for calculation, employed in rats by Garlick, Millward & James (1973).2. During a 6 h infusion, samples were taken from blood and muscle and at the end of the infusion from liver, muscle, pancreas, heart, duodenum, jejunum, ileum, colon, and skin. The specific radioactivity of free and protein-bound leucine and lysine was estimated.3. A quasi-steady-state in the specific radioactivity of free plasma leucine and lysine was reached within approximately 2 h, the rate-constants being 35 and 48/d respectively.4. The specific radioactivity of free leucine and lysine in plasma was used to calculate the flux of these amino acids. It was found to be higher than the daily intake.5. The average fractional rate of protein synthesis in muscle and heart was 8.1 %/d, in small and large intestine the values were 50 and 33 %/d respectively and in liver and pancreas more than 100 %/d.6. The calculation of protein synthetic rate in pig tissue using the constant-infusion method of labelled amino acids seems to be a suitable tool for study of this species.

scholarly journals Comparison of different techniques for estimating rates of protein synthesis in vivo in healthy and bacteraemic rats

1985 ◽  
Vol 226 (1) ◽  
pp. 37-42 ◽  
Author(s):  
J J Pomposelli ◽  
J D Palombo ◽  
K J Hamawy ◽  
B R Bistrian ◽  
G L Blackburn ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Rectus Muscle ◽  
Stochastic Modelling ◽  
Whole Body ◽  
Constant Infusion ◽  
Second Phase ◽  
Sprague Dawley ◽  
Body Protein ◽  
To Receive

Previous studies have reported that use of a flooding dose of radiolabelled amino acid is a more precise technique than the constant infusion of tracer quantities for determining rates of protein synthesis in rapidly turning-over tissues in the rat. However, there has been little direct investigation comparing different methods under comparable conditions. Initially, 12 healthy male Sprague-Dawley rats, weighing approx. 100 g, were randomized to receive either a bolus intravenous injection of 100 mumol of L-leucine (containing 30 microCi of [1-14C]leucine)/100 g body wt., or a continuous 2 h tracer infusion of [14C]leucine. In the second phase of the experiment, 12 additional rats were intravenously injected with 1 × 10(8) colony-forming units of Pseudomonas aeruginosa and 16 h later randomized to receive one of two infusions described above. Total protein synthesis as well as fractional synthesis rates were determined in liver, rectus muscle and whole body. Synthesis rates measured in liver, muscle and whole body were significantly higher in bacteraemic rats than in healthy rats. The flooding-dose methodology gave significantly higher estimates of protein synthesis in the liver, skeletal muscle and whole body than did the continuous-infusion method using direct measurement of the acid-soluble fraction from the respective tissue. Indirect estimates of whole-body protein synthesis based on plasma enrichments and stochastic modelling gave the lowest values.

Compartmental model of leucine kinetics in humans

1991 ◽  
Vol 261 (4) ◽  
pp. E539-E550 ◽  
Author(s):  
C. Cobelli ◽  
M. P. Saccomani ◽  
P. Tessari ◽  
G. Biolo ◽  
L. Luzi ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Compartmental Model ◽  
Linear Time ◽  
A Priori ◽  
Normal Subjects ◽  
Whole Body ◽  
Constant Infusion ◽  
Individual Subject ◽  
Domain Of Validity

The complexity of amino acid and protein metabolism has limited the development of comprehensive, accurate whole body kinetic models. For leucine, simplified approaches are in use to measure in vivo leucine fluxes, but their domain of validity is uncertain. We propose here a comprehensive compartmental model of the kinetics of leucine and alpha-ketoisocaproate (KIC) in humans. Data from a multiple-tracer administration were generated with a two-stage (I and II) experiment. Six normal subjects were studied. In experiment I, labeled leucine and KIC were simultaneously injected into plasma. Four plasma leucine and KIC tracer concentration curves and label in the expired CO2 were measured. In experiment II, labeled bicarbonate was injected into plasma, and labeled CO2 in the expired air was measured. Radioactive (L-[1-14C]leucine, [4,5-3H]KIC, [14C]bicarbonate) and stable isotope (L-[1-13C]leucine, [5,5,5-2H3]KIC, [13C]bicarbonate) tracers were employed. The input format was a bolus (impulse) dose in the radioactive case and a constant infusion in the stable isotope case. A number of physiologically based, linear time-invariant compartmental models were proposed and tested against the data. The model finally chosen for leucine-KIC kinetics has 10 compartments: 4 for leucine, 3 for KIC, and 3 for bicarbonate. The model is a priori uniquely identifiable, and its parameters were estimated with precision from the five curves of experiment I. The separate assessment of bicarbonate kinetics (experiment II) was shown to be unnecessary. The model defines masses and fluxes of leucine in the organism, in particular its intracellular appearance from protein breakdown, its oxidation, and its incorporation into proteins. An important feature of the model is its ability to estimate leucine oxidation by resolving the bicarbonate model in each individual subject. Finally, the model allows the assessment of the domain of validity of the simpler commonly used models.

scholarly journals A Kinetic Method for the Measurement of Zinc Influx In Vivo in the Rainbow Trout, and the Effects of Waterborne Calcium on Flux Rates

1989 ◽  
Vol 142 (1) ◽  
pp. 425-446 ◽  
Author(s):  
D. J. SPRY ◽  
C. M. WOOD
Keyword(s):  
Rainbow Trout ◽  
Plasma Sample ◽  
Kinetic Method ◽  
Whole Body ◽  
Constant Infusion ◽  
Linear Component ◽  
Experimental Apparatus ◽  
Body Counting ◽  
Whole Body Counting

Three methods were evaluated to measure rate of influx of Zn into rainbow trout. The first two, disappearance of 65Zn from the water and whole-body counting, overestimated influx when compared with a third method which used a terminal plasma sample to calculate influx. The cause of the overestimate was a short-term adsorption phenomenon to both the experimental apparatus and the exterior of the fish. The third method measured only Zn which entered the fish. This method entailed ‘calibration’ of cannulated trout by constant infusion of small amounts of radiolabelled Zn. This was analogous to the entry of Zn into fish across the gill. After 24–36 h of infusion, plasma radioactivity reached a steadystate concentration which was a simple linear function of the rate of infusion. This relationship was then used to predict influx from a single terminal plasma sample from uncannulated trout exposed to radiolabelled Zn in the water. Trout acclimated to tapwater (Ca2+ = 2.0 mequivl−1) and exposed to Zn (1.5-45.9 μequivl−1; 0.05-1.5 mgl−1) showed saturable uptake which was apparently first order with no significant linear component. The apparent Jmax and Km were 314 nequiv kg−1 h−1 and 7.3 μequivl−1 (0.24 mgl−1), respectively. Acutely raising the waterborne [Ca2+] (4.7 and 9.7 mequivl−1) over the same range of [Zn] revealed a competitive type of interaction - little change in Jmax, with increased Km. When Ca2+ was acutely removed (0.05 and 1.02 mequivl−1) by the use of artificial soft water, significant linear influx occurred in addition to the saturable uptake noted at higher [Ca2+], suggesting the opening of a paracellular leak. Calculation of the inhibitor constant for Ca2+ yielded a value of 0.48 mequivl−1. This value is similar to the Km for Ca2+ when it was a transported substrate (0.28 ± 0.07 mequivl−1). The true Km for Zn transport in the absence of Ca2+ was 1.0 μequivl−1 (0.06 mgl−1). These data showed Zn influx to be saturable and strongly dependent upon waterborne [Ca2+], perhaps traversing the gill in a manner similar to Ca2+.

Measuring whole-body actin/myosin protein breakdown in mice using a primed constant stable isotope-infusion protocol

2003 ◽  
Vol 104 (6) ◽  
pp. 585-590 ◽  
Author(s):  
Yvonne L. J. VISSERS ◽  
Maarten F. VON MEYENFELDT ◽  
Valeria B. BRAULIO ◽  
Yvette C. LUIKING ◽  
Nicolaas E. P. DEUTZ
Keyword(s):  
Stable Isotope ◽  
Total Protein ◽  
Myofibrillar Protein ◽  
Whole Body ◽  
Constant Infusion ◽  
Protein Breakdown ◽  
Net Protein ◽  
Infusion Protocol

To measure actin/myosin protein breakdown, the 24 h excretion of Nτ-methylhistidine (3MH) is used. However, in mice, this method is invalid. Therefore we have developed a liquid chromatography-MS technique to measure the tracer/tracee ratio and concentration of 3MH in plasma, enabling an in vivo primed constant infusion protocol with a deuterated stable isotope of 3MH. We tested this model by giving a primed constant infusion of L-[3-methyl-2H3]histidine, L-[phenyl-2H5]phenylalanine and L-[phenyl-2H2]tyrosine to three anaesthetized experimental groups: mice receiving saline intraperitoneally (i.p.) (CON), mice receiving saline i.p. and starved for 9 h (STA), and mice receiving lipopolysaccharide i.p. and starved for 9 h (STA + LPS). The contribution of myofibrillar to total protein breakdown was significantly lower in the STA group than the CON group (30±4% and 54±14% respectively; P<0.05), and was significantly higher in the STA + LPS group than the STA group (52±7% and 30±4% respectively; P<0.05). Whole-body myofibrillar protein breakdown, total protein breakdown, protein synthesis and net protein breakdown were not different between the groups. We conclude that this in vivo primed constant stable isotope-infusion protocol can give valuable information about the role of actin/myosin protein breakdown in mice.

scholarly journals Immune system stimulation increases the plasma cysteine flux and whole-body glutathione synthesis rate in starter pigs1

2019 ◽  
Vol 97 (9) ◽  
pp. 3871-3881 ◽  
Author(s):  
Anoosh Rakhshandeh ◽  
Cornelis F M de Lange ◽  
John K Htoo ◽  
Abbasali Gheisari ◽  
Amanda R Rakhshandeh
Keyword(s):  
Small Intestine ◽  
Immune System ◽  
Large Intestine ◽  
Specific Radioactivity ◽  
Whole Body ◽  
Constant Infusion ◽  
Synthesis Rate ◽  
Limiting Factor ◽  
Sterile Saline ◽  
Amino Acid Requirements

Abstract Glutathione (GSH) is the major intracellular thiol that plays a role in numerous detoxification, bio-reduction, and conjugation reactions. The availability of Cys is thought to be the rate-limiting factor for the synthesis of GSH. The effects of immune system stimulation (ISS) on GSH levels and the GSH synthesis rate in various tissues, as well as the plasma flux of Cys, were measured in starter pigs fed a sulfur AA (SAA; Met + Cys) limiting diet. Ten feed-restricted gilts with initial body weight (BW) of 7.0 ± 0.12 kg were injected i.m. twice at 48-h intervals with either sterile saline (n = 4; ISS−) or increasing amounts of Escherichia coli lipopolysaccharide (n = 6; ISS+). The day after the second injection, pigs received a primed constant infusion of 35S-Cys (9,300 kBq/pig/h) for 5 h via a jugular catheter. Blood and tissue free Cys and reduced GSH were isolated and quantified as the monobromobimane derivatives by HPLC. The rate of GSH synthesis was determined by measurement of the specific radioactivity of GSH and tissue free Cys at the end of the infusion period. Plasma Cys and total SAA levels were reduced (16% and 21%, respectively), but plasma Cys flux was increased (26%) by ISS (P < 0.05). Immune system stimulation increased GSH levels in the plasma (48%; P < 0.05), but had no effect on GSH levels in the liver, small and large intestines, heart, muscle, spleen, kidney, lung, and erythrocytes. The fractional synthesis rate (FSR) of GSH was higher (P < 0.05) in the liver (34%), small intestine (78%), large intestine (72%), heart (129%), muscle (37%), and erythrocytes (47%) of ISS+ pigs compared to ISS− pigs. The FSR of GSH tended (P = 0.08) to be higher in the lungs (45%) of ISS+ pigs than in ISS− pigs. The absolute rate of GSH synthesis was increased by ISS (mmol/kg wet tissue/d ± SE, ISS− vs. ISS+; P < 0.05) in the liver (5.22 ± 0.22 vs. 7.20 ± 0.59), small intestine (2.54 ± 0.25 vs. 4.52 ± 0.56), large intestine (0.61 ± 0.06 vs. 1.06 ± 0.16), heart (0.21 ± 0.03 vs. 0.48 ± 0.08), lungs (1.50 ± 0.10 vs. 2.90 ± 0.21), and muscle (0.21 ± 0.03 vs. 0.34 ± 0.04), but it remained unchanged in erythrocytes, the kidney, and the spleen (P > 0.80). The current findings suggest that GSH synthesis is increased during ISS, contributing to enhanced maintenance sulfur amino acid requirements in starter pigs during ISS.

Altered partition of threonine metabolism in pigs by protein-free feeding or starvation

1991 ◽  
Vol 261 (6) ◽  
pp. E748-E757 ◽  
Author(s):  
O. Ballevre ◽  
M. L. Houlier ◽  
J. Prugnaud ◽  
G. Bayle ◽  
D. Bercovici ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Protein S ◽  
Growing Pigs ◽  
Threonine Dehydratase ◽  
Balanced Diet ◽  
Liver Homogenates ◽  
Free Feeding ◽  
Highly Correlated ◽  
Protein Free Diet

Kinetic aspects of threonine (Thr) metabolism were examined in growing pigs fed a well-balanced diet (C), an isocaloric protein-free diet (PF), or starved (S) for 48 h. With the use of continuous simultaneous infusion of L-[1-13C]Thr, [1-14C]sarcosine, and 2-[1-14C]ketobutyrate (KB) for 10 h, estimates were made of rates of Thr incorporated into protein (S), released from body proteins (B), and oxidized through the catabolic pathways of L-Thr 3-dehydrogenase (TDG) and threonine dehydratase (TDH). In the C group S was 185, B was 138, Thr disposal to glycine (DRThr-Gly) was 47, and Thr disposal to KB (DRThr-KB) was 7 mumol.h-1.kg-1. Consequently, Thr balance was +48 mumol.h-1.kg-1. In the PF-fed pigs, S, B, DRThr-Gly, and DRThr-KB were significantly reduced by 38, 15, 74, and 75%, respectively. In the S group, S, B, and DRThr-Gly were significantly reduced by 47, 17, and 55%, respectively, but DRThr-KB was similar to the C group. DRThr-Gly in all groups was highly correlated with TDG enzyme activity measured in liver homogenates. By contrast with in vivo results, TDH enzyme activity was increased by 88% (P less than 0.05) in the S group and decreased by 27% (not significant) in the PF group compared with the C group. The TDH pathway accounted for 13, 12, and 27% of total Thr oxidation in the C, PF, and S groups, respectively. These results suggest that Thr conservation in protein-depleted states (PF and S groups) occurred mainly by a decrease of Thr oxidation and that the partition through these pathways was only altered when energy was completely withdrawn.

Gastrointestinal tract, hepatic, hindlimb, and renal recovery of CO2 in vivo

2000 ◽  
Vol 89 (5) ◽  
pp. 2000-2006 ◽  
Author(s):  
Jennifer D. Gresham ◽  
Koji Okamura ◽  
Phillip E. Williams ◽  
Kareem Jabbour ◽  
Paul J. Flakoll
Keyword(s):  
Gastrointestinal Tract ◽  
Pool Size ◽  
In Vivo Studies ◽  
Whole Body ◽  
Constant Infusion ◽  
Potential Contribution ◽  
Experimental Conditions ◽  
Rate Of Decay ◽  
Total Body

Whole body oxidative rates of labeled substrates are often measured by collecting expired air and determining the amount of labeled CO2 that is produced. However, the CO2 produced may not be completely recovered under all circumstances, and there is a wide variation in values reported under different experimental conditions (∼50–100%). The potential contribution of specific organs to this variation has not been defined. In vivo studies using healthy, postabsorptive, multicatheterized conscious canines were conducted to determine gastrointestinal tract, hepatic, hindlimb, and renal recoveries of NaH14CO3 during a 180-min constant infusion [0.022 ± 0.002 (SE) μCi · kg−1 · min−1]. Before the constant infusion period, a bolus infusion of NaH14CO3 (1.76 ± 0.16 μCi/kg) was given, and the rate of decay in blood was measured over a 15-min period to determine pool size. The pool size for the distribution of14CO2 was ∼80% of the total body pool (16.0 ± 1.7 liters). Whole body recovery was 97.2 ± 6.7%. The recoveries across the liver, gut, leg, and kidney were 99.9 ± 1.3, 98.0 ± 1.4, 96.7 ± 2.6, and 99.9 ± 2.1%, respectively. In conclusion, hepatic, gastrointestinal tract, hindlimb, and renal recoveries of CO2 in vivo were near 100%, suggesting that CO2 loss is not greater in gluconeogenic organs and that corrections for incomplete recovery of CO2, when measuring oxidation of substrates across these organs under normal postabsorptive conditions, would be very minor.

scholarly journals Studies on the metabolism of 5α-androst-16-en-3-one in boar testis in vivo

1974 ◽  
Vol 144 (2) ◽  
pp. 347-352 ◽  
Author(s):  
Y. A. Saat ◽  
D. B. Gower ◽  
F. A. Harrison ◽  
R. B. Heap
Keyword(s):  
Venous Blood ◽  
Specific Radioactivity ◽  
Testicular Tissue ◽  
Constant Rate ◽  
Sexually Mature ◽  
Venous Plasma

1. [5α-3H]5α-Androst-16-en-3-one (5α-androstenone) was infused at a constant rate for 180min into the spermatic artery of a sexually mature boar. Samples of spermatic-venous blood were collected at 1min intervals for the first 10min of the infusion and thereafter at 15min intervals for the first hour, then at 64, 125, 155 and 172min. After infusion, the testis was removed and immediately cooled to −196°C. 2. From both the testicular tissue and the spermatic-venous plasma, endogenous and3H-labelled androst-16-enes were isolated, characterized and quantitatively determined and their specific radioactivity was calculated. 3. The specific radioactivities of 5α-androstenore, 5α-androst-16-en-3α-ol and 5α-androst-16-en-3β-ol (an-α and an-β) in testicular tissue were different from those in the spermatic-venous plasma, suggesting that these compounds may be present in more than one compartment of the testis and differentially secreted into the spermatic-venous blood. 4. The ratios of the specific radioactivities of an-α and an-β to their respective sulphate conjugates in the testicular tissue were less than the ratios of the same compounds in the spermatic-venous plasma. 5. The patterns of secretion of these labelled compounds in the spermatic-venous blood during the period of infusion were demonstrated. 6. The urine that accumulated during the infusion was analysed and found to contain3H-labelled an-β, conjugated as both glucuronide and sulphate, the specific radioactivities of which were determined. Little or no androst-16-enes occurred as free steroids. 7. The presence of an-β glucuronide in the urine is discussed.

Effect of Thymol or Diphenyliodonium Chloride on Performance, Gut Fermentation Characteristics, and Campylobacter Colonization in Growing Swine†‡

2012 ◽  
Vol 75 (4) ◽  
pp. 758-761 ◽  
Author(s):  
ROBIN C. ANDERSON ◽  
NATHAN A. KRUEGER ◽  
KENNETH J. GENOVESE ◽  
THADDEUS B. STANTON ◽  
KATHRYN M. MacKINNON ◽  
...  
Keyword(s):  
Feed Intake ◽  
Alimentary Tract ◽  
Live Weight ◽  
Growing Pigs ◽  
Gut Contents ◽  
End Products ◽  
Daily Gain ◽  
Campylobacter Spp ◽  
Gut Fermentation

Food producing animals can be reservoirs of Campylobacter, a leading bacterial cause of human foodborne illness. Campylobacter spp. utilize amino acids as major carbon and energy substrates, a process that can be inhibited by thymol and diphenyliodonium chloride (DIC). To determine the effect of these potential additives on feed intake, live weight gain, and gut Campylobacter levels, growing pigs were fed standard grower diets supplemented with or without 0.0067 or 0.0201% thymol or 0.00014 or 0.00042% DIC in a replicated study design. Diets were offered twice daily for 7 days, during which time daily feed intake (mean ± SEM, 2.39 ± 0.06 kg day−1) and daily gain (0.62 ± 0.04 kg day−1) were unaffected (P &gt; 0.05) by treatment. Pigs treated with DIC but not thymol tended to have lower rectal Campylobacter levels (P = 0.07) (5.2 versus 4.2 and 4.4 log CFU g−1 rectal contents for controls and 0.00014% DIC and 0.00042% DIC, respectively; SEM = 0.26). However, DIC or thymol treatments did not affect (P &gt; 0.05) ileal or cecal Campylobacter (1.6 ± 0.17 and 4.5 ± 0.26 log CFU g−1, respectively), cecal total culturable anaerobes (9.8 ± 0.10 log CFU g−1), or accumulations of major fermentation end products within collected gut contents. These results suggest that thymol and DIC were appreciably absorbed, degraded, or otherwise made unavailable in the proximal alimentary tract and that encapsulation technologies will likely be needed to deliver effective concentrations of these compounds to the lower gut to achieve in vivo reductions of Campylobacter.

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