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Biomedical subjects

P Cartier

Publications and source records attributed to P Cartier.

At least 73 records · Page 4Linked to original sources
PubMed1981

Quantitation of 2-ketoacids in biological fluids by gas chromatography chemical ionization mass spectrometry of O-trimethylsilyl-quinoxalinol derivatives.

A very sensitive and specific method of 2-ketoacid determination in various biological fluids using gas chromatography chemical ionization mass spectrometry of O-trimethylsilyl-quinoxalinol derivatives is described. After derivatization with o-phenylenediamine in acidic medium and extraction, the 2-ketoacids, and the 2-ketovaleric acid used as internal standard, are silylated and resolved on a capillary column and their concentrations automatically determined by monitoring the m/z values corresponding to their respective protonated molecular ions, using ammonia as reactant gas. The detection limit is below 50 ng ml-1 of each 2-ketoacid. The recoveries of 2-ketoacids from urine and plasma were between 97 and 104%. Problems encountered with interfering substances were tested for and discussed. This method has been applied successfully to various metabolic disorders characterized by an accumulation of aliphatic 2-ketoacids. The metabolic interrelationship of branched chain 2-ketoacids and other compounds, especially pyruvate, is discussed.

Amniotic Fluid↗
PubMed1980

The use of formic acid in carrier gas. Rapid method for identification and determination of phytanic acid by gas chromatography-mass spectrometry-chemical ionization.

A rapid gas chromatographic method to determine phytanic acid in plasma from Refsum's disease is described. After a brief alkaline hydrolysis of lipids, the biological sample is directly injected into a glass pre-column; an acid carrier gas (formic acid in nitrogen) is used to displace the long-chain fatty acids from their sodium salts and from their binding to proteins. Formic acid introduced through the column may also be used as a reagent gas for chemical ionization in combined gas chromatography--mass spectrometry; fatty acids (C14 to C18:2 and phytanic acid) are easily identified by their M + 1 (base peak) and M - 17 peaks. The described procedure is also suitable for studying normal fatty acids from plasma lipids.

Eicosanoic Acids↗
PubMed1980

[Hereditary deficiency in adenine phosphoribosyltransferase: a metabolic cause of urinary lithiasis in children (author's transl)].

Complete lack of adenine phosphoribosyltransferase (APRT) is a not uncommon cause of urinary lithiasis in young children. The calculi are made up of a very poorly soluble substance, 2,8-dihydroxyadenine, which results from the oxidation of adenine by xanthinoxidase. A study of the 7 cases of APRT deficiency hitherto published (including 5 cases with lithiasis) shows that the diagnosis is rarely made, since the conventional methods of urinary stone analysis are unable to distinguish dihydroxyadenine from uric acid. This form of lithiasis can be prevented by inhibiting xanthinoxidase with allopurinol. The remarkable efficacy of this treatment and the frequent severity of the disease should raise the possibility of 2,8-dihydroxyadenine lithiasis in very case of alleged uric acid lithiasis in young children.

Adenine↗
PubMed1980

Enzymatic activities on purine pyrimidine metabolism in nine mycoplasma species contaminating cell cultures.

The study of mycoplasma enzymes involved in nucleotide degradation and base salvage pathways allowed determination of enzyme profiles for some species. The activity of adenosine phosphorylase seems to be the biochemical test of choice to detect mycoplasma contamination in cell cultures. All mycoplasmas tested had a very high level of activity compared to very low activity in human cell cultures, rendering the technic sensitive even at a low degree of contamination.

Cells, Cultured↗
PubMed1978

[Xanthinuria (author's transl)].

Xanthinuria, described in 1954 by Dent and Philpot, is a rare metabolic disorder, characterised by a deficiency in xanthine-oxidase, a key enzyme in the synthesis of uric acid. It results in hypouricaemia and hypouricuria, the urinary excretion of products of purine synthesis taking place in the form of uric acid precursors: hypoxanthine and xanthine. By virtue of the very slight solubility of xanthine, this xanthinuria may cause urinary lithiasis, in general occurring early. More often, however, the disease is asymptomatic and diagnosed following the chance discovery of hypouricaemia. We report 6 recent cases.

Adolescent↗
PubMed1978

The effects of pyruvate concentration, dichloroacetate and alpha-cyano-4-hydroxycinnamate on gluconeogenesis, ketogenesis and [3-hydroxybutyrate]/[3-oxobutyrate] ratios in isolated rat hepatocytes.

1. In isolated rat hepatocytes incubated with pyruvate, ketogenesis increased with increasing pyruvate concentrations and decreased under the influence of 1 mM-alpha-cyano-4-hydroxycinnamate, a known inhibitor of pyruvate transport. Ketogenesis from pyruvate was higher by 30% in hepatocytes prepared from starved than from fed rats. 2. With pyruvate as substrate, 2 mM-dichloroacetate had no effect on ketogenesis of starved-rat hepatocytes, but increased ketogenesis of fed-rat hepatocytes to the 'starved' value. Gluconeogenesis from pyruvate, lactate and alanine, but not from glycerol, was inhibited by dichloroacetate. Both increased ketogenesis and decreased gluconeogenesis may result from an inhibition of pyruvate carboxylase by dichloroacetate. 3. Mitochondria were rapidly isolated from incubated hepatocytes, and [3-hydroxybutyrate]/[3-oxobutyrate] ratios were measured in the mitochondrial pellet ('mitochondrial' ratios) and in whole-cell suspensions ('total' ratios). Increasing pyruvate concentrations increased mitochondrial and decreased total ratios. In the presence of pyruvate (2 to 10 mM), dichloroacetate decreased mitochondrial and increased total ratios.

Acetoacetates↗
PubMed1978

Giant hyperplastic parathyroid gland in the mediastinum--partially cystic and calcified.

A large, calcified paratracheal mass was identified in a patient with secondary hyperparathyroidism. The mass proved to be a giant, calcified, cystic, hyperplastic parathyroid gland. Radiographic and ultrasonic imaging techniques were quite useful in diagnostic evaluation. Whenever a calcified mediastinal or neck mass is discovered, especially in a patient with hyperparathyroidism, parathyroid enlargement should be a diagnostic consideration.

Calcinosis↗
PubMed1977

Renal vein plasma adenosine 3',5'-cyclic monophosphate in renovascular hypertension.

The concentration of plasma adenosine 3',5'-cyclic monophosphate (cyclic AMP) and plasma renin activity (PRA) were measured concomitantly in blood from both renal veins and in arterial blood in 22 hypertensive patients. In the nine patients with true renovascular hypertension the concentration of plasma cyclic AMP was greater in the venous effluent of the kidney affected by the renal artery stenosis than in that of the unaffected or less affected kidney. The arteriovenous difference in cyclic AMP concentration was less on the affected side in all but one patient. The arteriovenous differences in PRA identified the affected kidney as the source of hyper-reninemia and showed that renin release from the other kidney was suppressed. In the 13 patients with hypertension associated with but unrelated to renal artery stenosis there were no consistent patterns of cyclic AMP concentration or PRA in the venous effluent of the kidneys or of their arteriovenous differences. In renovascular hypertension the venous effluent of the kidney affected by renal artery stenosis contains not only more renin but also more cyclic AMP, owing to either increased cyclic AMP production or decreased excretion or extraction of cyclic AMP by the affected kidney. This unilateral increase in cyclic AMP concentration may become a complementary diagnostic feature of true renovascular hypertension.

Cyclic AMP↗