Muscle Creatine: In Vivo Depletion by Feeding β-Guanidinopropionic Acid

1973 ◽  
Vol 51 (7) ◽  
pp. 1046-1049 ◽  
Author(s):  
Robert P. Shields ◽  
C. K. Whitehair
Keyword(s):  
Urinary Excretion ◽  
Young Male ◽  
Pregnant Female ◽  
Radioactivity Level ◽  
Muscle Creatine ◽  
Creatine Metabolism

The purpose of this work was to determine the in vivo effect of β-guanidinopropionic acid (β-GPA) on the metabolism of creatine. Diets containing the synthetic creatine analogue, β-GPA, were fed to pregnant female and young male rats.All rats receiving diets containing β-GPA developed the following signs of abnormal creatine metabolism: reduced muscle levels of creatine, reduced urinary excretion of creatinine, and an increase in urinary excretion of creatine.Twelve hours after an injection of creatine-1-14C, rats fed β-GPA had a lower radioactivity level (c.p.m.) in muscle but a higher level in urine than did rats fed the same diet without β-GPA.It is proposed that abnormal creatine metabolism results from an inhibition of creatine entry into muscle from plasma by β-GPA.

ÉTUDES IN VIVO SUR LE MÉTABOLISME DES ANDROGÉNES APRES ADMINISTRATION DE STÉROÏDES INHIBITEURS DE L'OVULATION

1965 ◽  
Vol 50 (1) ◽  
pp. 131-144 ◽  
Author(s):  
P. Mauvais-Jarvis ◽  
M. F. Jayle ◽  
J. Decourt ◽  
J. Louchart ◽  
J. Truffert
Keyword(s):  
Luteinizing Hormone ◽  
Urinary Excretion ◽  
Normal Subjects ◽  
Hormone Activity ◽  
Testosterone Production ◽  
Normal Men ◽  
Ethinyl Oestradiol

ABSTRACT Normal subjects and hirsute women with micropolycystic ovaries were treated with ethinyl-oestrenol + 3-methoxy-ethinyl-oestradiol (Lyndiol®), in view of studying the action of this compound on the production of androgens and on the urinary excretion of their metabolites. In normal men, the production of testosterone and the excretion of androsterone and aetiocholanolone are suppressed, whereas the excretion of other 17-ketosteroids and the production of dehydroepiandrosterone sulphate are unchanged. Moreover, the luteinizing hormone activity (LH) in plasma is depressed. It seems that the preparation inhibits specifically the testicular androgen production, by suppressing the hypothalamo-hypophyseal control of LH. Testosterone production and urinary 17-ketosteroid excretion are modified in the same way in women with Stein-Leventhal's syndrome. Physiopathological and therapeutical implications which come from these results are discussed.

ATYPICAL ADRENAL HYPERFUNCTION: IN VIVO STUDIES AND INCUBATIONS OF ADRENAL TISSUE WITH 4-14C PROGESTERONE

1968 ◽  
Vol 58 (3_Suppl) ◽  
pp. S5-S34
Author(s):  
Joseph W. Goldzieher ◽  
Leonard R. Axelrod ◽  
Arthur S. Weissbein
Keyword(s):  
Urinary Excretion ◽  
Clinical Features ◽  
In Vivo Studies ◽  
Acth Stimulation ◽  
Adrenal Tissue ◽  
Adrenal Hyperfunction

ABSTRACT Six women with atypical forms of adrenal cortical hyperfunction were studied by means of urinary excretion of 17-ketosteroids and 17-hydroxycorticoids and their response to ACTH stimulation and corticosteroid suppression. Unusual responses were observed, particularly with respect to the independence of 17-KS and 17-OHCS excretion. The adrenals of 3 patients were anatomically normal whereas the others showed hyperplasia. Minced adrenal tissue was incubated with 4-14C progesterone and the metabolites isolated and definitively identified. The pattern of biosynthesized corticosteroids showed great variation, and in some instances clarified certain clinical features. The pattern of certain C19-metabolites could not be studied adequately because of the use of a Δ4 rather than a Δ5 substrate.

scholarly journals Procyanidins are not bioavailable in rats fed a single meal containing a grapeseed extract or the procyanidin dimer B3

2002 ◽  
Vol 87 (4) ◽  
pp. 299-306 ◽  
Author(s):  
Jennifer L. Donovan ◽  
Adam Lee ◽  
Claudine Manach ◽  
Laurent Rios ◽  
Christine Morand ◽  
...  
Keyword(s):  
Gastrointestinal Tract ◽  
Urinary Excretion ◽  
Ring Structure ◽  
Future Research ◽  
Human Gastrointestinal Tract ◽  
Human Diet ◽  
Single Meal ◽  
Nutritional Effects ◽  
Grapeseed Extract

Flavanols are the most abundant flavonoids in the human diet where they exist as monomers, oligomers and polymers. In the present study, catechin, the procyanidin dimer B3 and a grapeseed extract containing catechin, epicatechin and a mixture of procyanidins were fed to rats in a single meal. After the meals, catechin and epicatechin were present in conjugated forms in both plasma and urine. In contrast, no procyanidins or conjugates were detected in the plasma or urine of any rats. Procyanidins were not cleaved into bioavailable monomers and had no significant effects on the plasma levels or urinary excretion of the monomers when supplied together in the grapeseed extract. We conclude that the nutritional effects of dietary procyanidins are unlikely to be due to procyanidins themselves or monomeric metabolites with the intact flavonoid-ring structure, as they do not exist at detectable concentrations in vivo. Future research should focus on other procyanidin metabolites such as phenolic acids and on the effects of the unabsorbed oligomers and polymers on the human gastrointestinal tract.

scholarly journals Simultaneous Assessment of Endothelial Function, Nitric Oxide Synthase Activity, Nitric Oxide–Mediated Signaling, and Oxidative Stress in Individuals with and without Hypercholesterolemia

2008 ◽  
Vol 54 (2) ◽  
pp. 292-300 ◽  
Author(s):  
Renke Maas ◽  
Edzard Schwedhelm ◽  
Lydia Kahl ◽  
Huige Li ◽  
Ralf Benndorf ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Endothelial Function ◽  
Urinary Excretion ◽  
Indirect Evidence ◽  
No Oxidation ◽  
Whole Body ◽  
Gas Chromatography Mass Spectrometry ◽  
Synthesis Rate ◽  
No Production

Abstract Background: Endothelial function is impaired in hypercholesterolemia and atherosclerosis. Based on mostly indirect evidence, this impairment is attributed to reduced synthesis or impaired biological activity of endothelium-derived nitric oxide (NO). It was the aim of this study to directly estimate and compare whole-body NO production in normo- and hypercholesterolemia by applying a nonradioactive stable isotope dilution technique in vivo. Methods: We enrolled 12 normocholesterolemic and 24 hypercholesterolemic volunteers who were all clinically healthy. To assess whole-body NO synthesis, we intravenously administered l-[guanidino-(15N2)]-arginine and determined the urinary excretion of 15N-labeled nitrate, the specific end product of NO oxidation in humans, by use of gas chromatography-mass spectrometry. In addition, we measured flow-mediated vasodilation (FMD) of the brachial artery, expression of endothelial NOS (eNOS) in platelets, plasma concentration of the endogenous NOS inhibitor asymmetric dimethylarginine (ADMA), and urinary excretion of 8-isoprostaglandin F2α (8-iso-PGF2α). Results: After infusion of l-[guanidino-(15N2)]-arginine, cumulative excretion of 15N-labeled-nitrate during 48 h was 40% [95% CI 15%–66%] lower in hypercholesterolemic than normocholesterolemic volunteers [mean 9.2 (SE 0.8) μmol vs 15.4 (2.3) μmol/l, P = 0.003]. FMD was on average 36% [4%–67%] lower in hypercholesterolemic than normocholesterolemic volunteers [6.3 (4.0)% vs 9.4 (4.6)%, P = 0.027]. Normalized expression of NOS protein in platelets was also significantly lower in hypercholesterolemic volunteers, whereas there were no significant differences in plasma ADMA concentration or urinary excretion of 8-iso-PGF2α between the 2 groups. Conclusions: This study provides direct evidence for a decreased whole body NO synthesis rate in healthy people with hypercholesterolemia.

ANDROGEN METABOLISM IN CONGENITAL ADRENAL HYPERPLASIA DUE TO 11 β-HYDROXYLASE DEFICIENCY

PEDIATRICS ◽  
1969 ◽  
Vol 44 (2) ◽  
pp. 201-208
Author(s):  
S. Douglas Frasier ◽  
Richard Horton ◽  
Robert A. Ulstrom
Keyword(s):  
Plasma Concentration ◽  
Urinary Excretion ◽  
Congenital Adrenal Hyperplasia ◽  
Conversion Ratio ◽  
Metabolic Clearance ◽  
Adrenal Hyperplasia ◽  
Metabolic Clearance Rate ◽  
Hydroxylase Deficiency ◽  
Glucocorticoid Administration

The plasma concentration of androstenedione and testosterone, metabolic clearance rate of androstenedione, and in vivo conversion ratio of androstenedione to testosterone have been studied in a normotensive 5-year-old female with congenital adrenal hyperplasia due to a deficiency of 11 β-hydroxylase. Prior to glucocorticoid administration, the urinary excretion of 17-ketosteroids varied from 2.2 to 4.9 mg/24 hours, urinary excretion of pregnanetriol varied from 0.7 to 2.2 mg/24 hours, and total 17-hydroxysteroid excretion varied from 1.2 to 7.5 mg/24 hours. Urinary tetrahydro-11-deoxy cortisol (TSH) was detected at a concentration of 550 µg/24 hours. The plasma concentration of androstenedione varied from 100 to 530 mµg/100 ml and the plasma concentration of testosterone varied from 40 to 90 mµg/100 ml. These values are significantly elevated when compared to those obtained in normal prepubertal females. Urinary steroid excretion and plasma androgen concentrations fell to normal in response to glucocorticoid administration. The metabolic clearance rate of androstenedione was 890 liters per day per M2 and the in vivo conversion ratio of androstenedione to testosterone was 11%. The calculated production rate of androstenedione was 4.7 mg per day per M2. Virilization in congenital adrenal hyperplasia due to 11 β-hydroxylase deficiency can be explained by an elevated plasma concentration of testosterone, which can be accounted for on the basis of conversion from androstenedione.

Comparison of the feedback effect of magnesium and calcium on parathyroid hormone secretion in man

1987 ◽  
Vol 113 (1) ◽  
pp. 117-122 ◽  
Author(s):  
O. Ferment ◽  
P. E. Garnier ◽  
Y. Touitou
Keyword(s):  
Parathyroid Hormone ◽  
Urinary Excretion ◽  
Hormone Secretion ◽  
Plasma Concentrations ◽  
Magnesium Salt ◽  
Saline Injection ◽  
Molar Basis ◽  
Magnesium Salts ◽  
High Doses

ABSTRACT Administration of high doses of magnesium is known to produce a decrease in parathyroid hormone (PTH) secretion in human patients but the effect of magnesium on the secretion of PTH in healthy man is not known. We have looked at the effect of a relatively moderate i.v. dose of magnesium (7·08 mmol) in seven healthy men. In addition and for comparison the effect of calcium (4·25 mmol) was studied. Two magnesium salts were considered, magnesium sulphate (MgSO4) and magnesium pyrrolidone carboxylate (MgPC). Four i.v. injections were given at 08.00 h (MgPC, NaCl (control), MgSO4 and Ca gluconate), with an interval of 1 week between each injection. Whatever the magnesium salt the variations in plasma concentrations of magnesium were the same whereas no change in erythrocyte magnesium was observed. Plasma concentration of C-terminal PTH did not show significant variations after MgPC or saline injection. Both MgSO4 and Ca gluconate produced a statistically significant 30% decrease in plasma PTH levels 45 min after the injection. The effect was more sustained with calcium (2 h) than with magnesium (45 min). The urinary excretion of magnesium was significantly higher after injection of MgSO4 than after MgPC. These results suggest (1) that magnesium was, on a molar basis, less potent than calcium in regulating PTH secretion in vivo, (2) that the nature of the magnesium salt used must be kept in mind for the interpretation of the effect of magnesium on PTH secretion in vivo and (3) that the decrease in plasma PTH can partly explain the larger urinary excretion of magnesium after MgSO4 than after MgPC. J. Endocr. (1987) 113, 117–122

scholarly journals Hereditary Antithrombin III Deficiency. Evidence of Increased Thrombin Formation in the Early Stage of Hemostasis

1977 ◽  
Author(s):  
F. Josso ◽  
M. H. Aurousseau ◽  
A. M. Fischer ◽  
M. D. Dautzenberg ◽  
S. Beguin
Keyword(s):  
Antithrombin Iii ◽  
Early Stage ◽  
Young Male ◽  
Massive Pulmonary Embolism ◽  
New Family ◽  
Mild Deficiency ◽  
Antithrombin Iii Deficiency ◽  
Thrombin Formation

High incidence of thromboembolism in observed in families with antithrombin III deficiency, despite the rather moderate defect (25 to 50 per cent) observed in the affected subjects, considered as heterozygous for the disease. The mechanism by which such a mild deficiency may promote thrombosis still remains unknown.A new family with antirhrombin III deficiency is reported, including three affected generations. Three young male adults of a same sibship died from massive pulmonary embolism aged from 22 to 28 years. In four living members of the family, three of which had antecedents of thrombophlebitis, antithrombin III level was close to 50 per cent by all assay methods used. Electro-phoretic and immunochemical studies failed to demonstrate any qualitative defect of the antithrombin III molecule.In these patients the only abnormalities of hemostasis lied in the early stage of the hemostatic pathway. In vitro, thrombin formation occured very rapidly after initiation of coagulation, as demonstrated by the kinetics of thrombin generation and factors V and VIII activation. In vivo, factors V and VIII were activated during bleeding much more rapidly than in controls and this activation was not suppressed by low doses of heparin (10 u./kg) as in the controls.These findings indicate that antithrombin III acts chiefly in the regulation balance of the early stages of hemostasis and thrombosis.

Validation of lactose[15N,15N]ureide as a tool to study colonic nitrogen metabolism

2005 ◽  
Vol 288 (5) ◽  
pp. G994-G999 ◽  
Author(s):  
Karen P. Geboes ◽  
Vicky De Preter ◽  
Anja Luypaerts ◽  
Bert Bammens ◽  
Pieter Evenepoel ◽  
...  
Keyword(s):  
Urinary Excretion ◽  
Nitrogen Metabolism ◽  
Proximal Colon ◽  
Fecal Excretion ◽  
In Vitro Experiments ◽  
Dietary Intakes ◽  
Nitrogen Pool ◽  
Different Types

In vitro experiments have shown that fermentation of carbohydrates prevents accumulation of nitrogen in the colon. Variable results have been obtained on modulation of dietary intakes in vivo. Lactose[15N,15N]-labeled ureide has been proposed as a tool to study colonic nitrogen metabolism. However, on oral administration of the marker, different urinary excretion patterns of the 15N label have been found. In this study, 50 mg lactose[15N,15N]ureide was directly instilled in the colon through an orocecal tube to investigate the colonic handling of this molecule in a direct way. In basal conditions, 42% (range, 37–48%) of labeled nitrogen administered as lactose[15N,15N]ureide was retrieved in urine after 72 h. A substantial variability in total urinary excretion of the label was found, but the urinary excretion pattern of the label was similar in all volunteers. When inulin, a fermentable carbohydrate, was administered together with the labeled marker, a significant decrease in urinary excretion of 15N after 72 h was found, to 29% (range, 23–34%). The effect of a smaller dose of inulin (250 mg) on colonic handling of lactose[15N,15N]ureide (50 mg), was investigated in another group of volunteers, and this time, fecal excretion of the marker was also evaluated. The results seem to indicate that fermentation of inulin causes an increased fecal excretion of the marker, thereby reducing urinary excretion but not retention in the human nitrogen pool. This instillation study shows that lactose[15N,15N]ureide is a tool with good properties to investigate the effect of different types of carbohydrates on nitrogen metabolism in the proximal colon in vivo.

Sustained-release dosage form of nitrofurantoin. Part 2. In vivo urinary excretion in man

1994 ◽  
Vol 11 (2) ◽  
pp. 137-140 ◽  
Author(s):  
G. Ertan ◽  
E. Karasulu ◽  
M. Abou-Nada ◽  
M. Tosun ◽  
A. Özer
Keyword(s):  
Sustained Release ◽  
Urinary Excretion ◽  
Dosage Form
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