Correction: Protein fractional synthesis rates within tissues of high- and low-active mice

In patients with the nephrotic syndrome, markedly increased levels of lipoprotein(a) (Lp(a)) concentration have been frequently reported, and it has been suggested that this may contribute to the increased cardiovascular risk in these patients. The mechanism, however, is not clear. In the present study, in vivo fractional synthesis rate of Lp(a) was measured using incorporation of the stable isotope 13C valine. Under steady-state conditions, fractional synthesis rate equals fractional catabolic rate (FCR). FCR of Lp(a) was estimated in five patients with the nephrotic syndrome and compared with five control subjects. The mean plasma Lp(a) concentration in the patients (1749+/-612 mg/L) was higher than in control subjects (553+/-96 mg/L). Two patients were heterozygous for apolipoprotein(a) (range, 19 to 30 kringle IV domains), whereas all control subjects were each homozygous with regard to apolipoprotein(a) phenotype (range, 18 to 28 kringle IV domains). The FCR of Lp(a) was comparable between control subjects (0.072+/-0.032 pools/d) and patients (0.064+/-0.029 pools/d) despite the wide variance in plasma concentration. This suggests that differences in Lp(a) levels are caused by differences in synthesis rate. Indeed, the absolute synthetic rate of Lp(a) correlated directly with plasma Lp(a) concentration (P < 0.0001) in all subjects. The present results demonstrate that increased synthesis, rather than decreased catabolism, causes elevated plasma Lp(a) concentrations in the nephrotic syndrome.

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Synthesis rate of plasma albumin is a good indicator of liver albumin synthesis in sepsis

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.2000.279.2.e244 ◽

2000 ◽

Vol 279 (2) ◽

pp. E244-E251 ◽

Cited By ~ 56

Author(s):

Benoît Ruot ◽

Denis Breuillé ◽

Fabienne Rambourdin ◽

Gerard Bayle ◽

Pierre Capitan ◽

...

Keyword(s):

Synthesis Rate ◽

Albumin Concentration ◽

Liver Protein ◽

Mrna Levels ◽

Albumin Synthesis ◽

Plasma Albumin ◽

Period 2 ◽

Fractional Synthesis ◽

Plasma Albumin Concentration

Plasma albumin is well known to decrease in response to inflammation. The rate of albumin synthesis from both liver and plasma was measured in vivo by use of a large dose ofl-[2H3-14C]valine in rats injected intravenously with live Escherichia coli and in pair-fed control rats during the acute-phase period (2 days postinfection). The plasma albumin concentration was reduced by 50% in infected rats compared with pair-fed animals. Infection induced a fall in both liver albumin mRNA levels and albumin synthesis relative to total liver protein synthesis. However, absolute liver albumin synthesis rate (ASR) was not affected by infection. In plasma, albumin fractional synthesis rate was increased by 50% in infected animals compared with pair-fed animals. The albumin ASR estimated in the plasma was similar in the two groups. These results suggest that hypoalbuminemia is not due to reduced albumin synthesis during sepsis. Moreover, liver and plasma albumin ASR were similar. Therefore, albumin synthesis measured in the plasma is a good indicator of liver albumin synthesis.

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Resistance training reduces the acute exercise-induced increase in muscle protein turnover

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1999.276.1.e118 ◽

1999 ◽

Vol 276 (1) ◽

pp. E118-E124 ◽

Cited By ~ 67

Author(s):

S. M. Phillips ◽

K. D. Tipton ◽

A. A. Ferrando ◽

R. R. Wolfe

Keyword(s):

Resistance Training ◽

Resistance Exercise ◽

Acute Exercise ◽

Muscle Protein ◽

Exercise Bout ◽

Muscle Contractions ◽

Breakdown Rates ◽

Single Bout ◽

Fractional Synthesis ◽

Exercise Induced

We examined the effect of resistance training on the response of mixed muscle protein fractional synthesis (FSR) and breakdown rates (FBR) by use of primed constant infusions of [2H5]phenylalanine and [15N]phenylalanine, respectively, to an isolated bout of pleiometric resistance exercise. Trained subjects, who were performing regular resistance exercise (trained, T; n = 6), were compared with sedentary, untrained controls (untrained, UT; n = 6). The exercise test consisted of 10 sets (8 repetitions per set) of single-leg knee flexion (i.e., pleiometric muscle contraction during lowering) at 120% of the subjects’ predetermined single-leg 1 repetition maximum. Subjects exercised one leg while their contralateral leg acted as a nonexercised (resting) control. Exercise resulted in an increase, above resting, in mixed muscle FSR in both groups (UT: rest, 0.036 ± 0.002; exercise, 0.0802 ± 0.01; T: rest, 0.045 ± 0.004; exercise, 0.067 ± 0.01; all values in %/h; P< 0.01). In addition, exercise resulted in an increase in mixed muscle FBR of 37 ± 5% (rest, 0.076 ± 0.005; exercise, 0.105 ± 0.01; all values in %/h; P < 0.01) in the UT group but did not significantly affect FBR in the T group. The resulting muscle net balance (FSR − FBR) was negative throughout the protocol ( P < 0.05) but was increased in the exercised leg in both groups ( P < 0.05). We conclude that pleiometric muscle contractions induce an increase in mixed muscle protein synthetic rate within 4 h of completion of an exercise bout but that resistance training attenuates this increase. A single bout of pleiometric muscle contractions also increased the FBR of mixed muscle protein in UT but not in T subjects.

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Age-related changes in collagen synthesis and degradation in rat tissues. Importance of degradation of newly synthesized collagen in regulating collagen production

Biochemical Journal ◽

10.1042/bj2760307 ◽

1991 ◽

Vol 276 (2) ◽

pp. 307-313 ◽

Cited By ~ 120

Author(s):

P K Mays ◽

R J McAnulty ◽

J S Campa ◽

G J Laurent

Keyword(s):

Skeletal Muscle ◽

Collagen Synthesis ◽

Rat Tissues ◽

Age Related ◽

Developmental Growth ◽

Cross Links ◽

Fractional Synthesis ◽

Synthesis And Degradation ◽

Age Related Changes

During developmental growth, collagens are believed to be continuously deposited into an extracellular matrix which is increasingly stabilized by the formation of covalent cross-links throughout life. However, the age-related changes in rates of synthetic and degradative processes are less well understood. In the present study we measured rates of collagen synthesis in vivo using a flooding dose of unlabelled proline given with [14C]proline and determining production of hydroxy[14C]proline. Degradation of newly synthesized collagen was estimated from the amount of free hydroxy [14C]proline in tissues 30 min after injection. Collagen fractional synthesis rates ranged from about 5%/day in skeletal muscle to 20%/day in hearts of rats aged 1 month. At 15 months of age, collagen fractional synthesis rates had decreased markedly in lung and skin, but in skeletal muscle and heart, rates were unchanged. At 24 months of age, synthesis rates had decreased by at least 10-fold in all tissues, compared with rates at 1 month. The proportion of newly synthesized collagen degraded ranged from 6.4 +/- 0.4% in skin to 61.6 +/- 5.0% in heart at 1 month of age. During aging the proportion degraded increased in all tissues to maximal values at 15 months, ranging from 56 +/- 7% in skin to 96 +/- 1% in heart. These data suggest that there are marked age-related changes in rates of collagen metabolism. They also indicate that synthesis is active even in old animals, where the bulk of collagens produced are destined to be degraded.

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Short-term protein intake increases fractional synthesis rate of muscle protein in the elderly: meta-analysis

Nutrition Research and Practice ◽

10.4162/nrp.2010.4.5.375 ◽

2010 ◽

Vol 4 (5) ◽

pp. 375 ◽

Cited By ~ 8

Author(s):

Hyun-Soo Gweon ◽

Hee-Ja Sung ◽

Dae-Hee Lee

Keyword(s):

Protein Intake ◽

Muscle Protein ◽

Meta Analysis ◽

The Elderly ◽

Synthesis Rate ◽

Short Term ◽

Fractional Synthesis Rate ◽

Fractional Synthesis

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Effect of ursodeoxycholic acid on lipid metabolism: through the prism of evidence from 2019.

Herald of Pancreatic Club ◽

10.33149/vkp.2020.01.11 ◽

2020 ◽

Vol 46 (1) ◽

pp. 83-88

Author(s):

N. B. Gubergrits ◽

N.V. Byelyayeva ◽

T. L. Mozhyna ◽

G. M. Lukashevich ◽

P. G. Fomenko

Keyword(s):

Lipid Metabolism ◽

Bile Acid ◽

Bile Acids ◽

De Novo ◽

Gallstone Disease ◽

Farnesoid X Receptor ◽

Synthesis Rate ◽

Primary Biliary Cholangitis ◽

Fractional Synthesis Rate ◽

Fractional Synthesis

After the discovery of the method of ursodeoxycholic acid’s (UDCA) synthesis and the publication of evidence confirming its ability to reduce the lithogenic properties of bile, active clinical use of UDCA began in the world. This drug, which has pleiotropic effect (choleretic, cytoprotective, immunomodulatory, antiapoptic, litholytic, hypocholesterolemic), has proven its effectiveness in the treatment various diseases: primary biliary cholangitis, intrahepatic cholestasis of pregnancy, gallstone disease. Being a tertiary bile acid, UDCA stimulates bile acid synthesis by reducing the circulating fibroblast growth factor 19 and inhibiting the activation of the farnesoid X-receptor (FXR), which leads to the induction of cholesterol-7α-hydroxylase, a key enzyme in the synthesis of bile acid de novo, mediating the conversion of cholesterol into bile acids. Changes in the formation of bile acids and cholesterol while taking UDCA intake is accompanied by activation of the main enzyme of cholesterol synthesis - 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR). Under the influence of UDCA the activity of stearoyl-Coa desaturase (SCD) in visceral white adipose tissue increases. According to studies conducted in 2019, UDCA improves lipid metabolism by regulating the activity of the ACT/mTOR signaling pathway, reduces the synthesis of cholesterol, decreases the fractional synthesis rate of cholesterol and the fractional synthesis rate of triglycerides. It has been proved that UDCA is accompanied by a decrease in the level of total cholesterol and low density lipoprotein cholesterol.

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Basal and amino acid stimulated fractional synthesis rates of calf muscle protein subfractions in peripheral arterial disease

The FASEB Journal ◽

10.1096/fasebj.22.1_supplement.1095.4 ◽

2008 ◽

Vol 22 (S1) ◽

Author(s):

Demidmaa Tuvdendorj ◽

Robert R Wolfe ◽

Lois A Killewich

Keyword(s):

Amino Acid ◽

Peripheral Arterial Disease ◽

Muscle Protein ◽

Arterial Disease ◽

Calf Muscle ◽

Fractional Synthesis ◽

Peripheral Arterial

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Albumin synthesis in humans increases immediately following the administration of endotoxin

Clinical Science ◽

10.1042/cs1030525 ◽

2002 ◽

Vol 103 (5) ◽

pp. 525-531 ◽

Cited By ~ 18

Author(s):

Hans BARLE ◽

Anna JANUSZKIEWICZ ◽

Lars HÅLLSTRÖM ◽

Pia ESSÉN ◽

Margaret A. MCNURLAN ◽

...

Keyword(s):

Intravenous Injection ◽

Early Phase ◽

The Other ◽

Synthesis Rate ◽

Control Group ◽

Albumin Synthesis ◽

Fractional Synthesis Rate ◽

Before And After ◽

Fractional Synthesis ◽

Absolute Synthesis

In order to investigate the immediate (i.e. within 3h) response of albumin synthesis to the administration of endotoxin, as a model of a moderate and well controlled catabolic insult, two measurements employing L-[2H5]phenylalanine were performed in 16 volunteers. One group (n = 8) received an intravenous injection of endotoxin (4ng/kg; lot EC-6) immediately after the first measurement of albumin synthesis, whereas the other group received saline. A second measurement was initiated 1h later. In the endotoxin group, the fractional synthesis rate of albumin was 6.9±0.6%/day (mean±S.D.) in the first measurement. In the second measurement, a significant increase was observed (9.6±1.2%/day; P<0.001). The corresponding values in the control group were were 6.6±0.6%/day and 7.0±0.6%/day respectively (not significant compared with first measurement and P<0.001 compared with the second measurement in the endotoxin group). The absolute synthesis rates of albumin were 148±35 and 201±49mg·kg-1·day-1 before and after endotoxin (P<0.01). In the control group, the corresponding values were 131±21 and 132±20mg·kg-1·day-1 (not significant compared with the first measurement and P<0.01 compared with the second measurement in the endotoxin group). In conclusion, these results indicate that albumin synthesis increases in the very early phase after a catabolic insult, as represented by the administration of endotoxin.

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