Technique de dosage automatique de l'orthophosphate de grande fiabilité

Amic, J; Lairon, Denis; Hauton, J. C.

doi:10.1016/0009-8981(72)90256-2

Cited by 72 publications

(15 citation statements)

References 6 publications

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“…Pancreas was not assayed, since purified porcine pancreatic phospholipase A2 is quite active against C12PG.3 Plasma activity was 75% less than that of serum, which was not due to heparin, because the addition of heparin to serum did not reduce its activity (10 nmol min-' ml-' serum vs. 9.44 nmol min-' ml-' upon the addition of heparin 1:5). The location of ac-tivity was further investigated by bringing the serum to a density of 1.21 with KBr and centrifuging it at 45,000 rpm in a SW 50.1 rotor (Beckman Instruments Co., Inc.) for 24 h. The resulting serum was fractionated by piercing the bottom of the tubes. 96% of the activity was recovered, of which 59% was in the heaviest fraction.…”

Section: Resultsmentioning

confidence: 99%

“…Surface pressure was measured as surface area was contracted until film collapse occurred (46 dyn cm-'). This determination was performed in triplicate, as was the automated analysis for phosphorus in a measured quantity of the diC12PG sample (24 It should be noted that, unlike the case in bulk assays, only a small proportion of the enzyme added is actually at the surface of the reaction compartment. It is only this surface-adsorbed enzyme that is active.…”

Section: Enzyme Assaysmentioning

confidence: 99%

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Intestinal Phospholipase, a Novel Enzyme

Mansbach¹,

Piéroni²,

Verger³

1982

J. Clin. Invest.

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A B S T R A C T We evaluated phospholipase activity in the intestine of rats and other species. Phospholipase activity was assayed by a surface barostat technique or an egg yolk titration system. Mucosal activity was found only by the surface barostat technique with phosphatidylglycerol as substrate; it was not found with phosphatidylcholine as substrate in assays by either technique. In gut luminal fluid activity was found when both phosphatidylcholine and phosphatidylglycerol were used as substrate in assays by the surface barostat technique, and phosphatidylcholine as substrate yielded activity in egg yolk titration. In rats in which pancreatic juice had been diverted, mucosal and gut luminal phospholipase activity was greater than in controls, thus demonstrating that enzyme activity was not due to pancreatic phospholipase. Bacterial origin of phospholipase activity was excluded in that phospholipase activity was found in germ-free rats; gastric and salivary gland origins were excluded in that continued phospholipase activity was found in rats with gastric fistula. The physiological importance of the enzyme was established by the finding that rats with pancreatic fistula absorbed 111 ,umol of phosphatidylcholine and that controls absorbed 119 ,umol of a 135-gmol load. Activity was found to be three times greater in the distal than in the proximal intestine; in cryptal cells it was 10 times greater than in villus tip cells. 65% of the activity in the gut lumen was tightly bound to particulate matter. We propose that intestinal phospholipase may be important in gut bacterial control, in the digestion of vegetable matter (phosphatidylglycerol is a major phospholipid in both plants and bacteria), and in the digestion of phospholipids in the gut lumen.

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Section: Resultsmentioning

confidence: 99%

Section: Enzyme Assaysmentioning

confidence: 99%

Intestinal Phospholipase, a Novel Enzyme

Mansbach¹,

Piéroni²,

Verger³

1982

J. Clin. Invest.

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“…PC were determined by a semiautomatic colorimetric method [22]. BS and cholesterol were analyzed by thin-layer chromatography on silica gel (Ready plastic sheets Kieseigel F1500; Schleicher & Schuell-Serflam, Marseilles, France) using a development phase of chloroform:methanol:water (65/34/4, v/v/v) [23].…”

Section: Methodsmentioning

confidence: 99%

“…The radioactivity in bile was measured by liquid scintillation counting, as described above. Phospholipids were determined by a semiautomatic colorimetric method [22]. …”

Section: Methodsmentioning

confidence: 99%

Effects of Dexamethasone and Linoleic Acid on Hepatic Secretion of Biliary Lipids and Anionic Polypeptide Factor: In vivo and in vitro Studies

Domingo

E²,

Reynier³

et al. 1999

Digestion

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Synthetic glucocorticoids, such as dexamethasone, and diets enriched with unsaturated fatty acids have been shown to stimulate hepatic bile salt synthesis. This fact led us to investigate the effects of dexamethasone and linoleic acid supplementation on bile secretion. Cholesterol (Ch) and phospholipid secretions are bile acid dependent. Ch and phospholipid in bile are also highly bound to a small apoprotein, the anionic polypeptide factor (APF). In bile, APF may play a physiological role in stabilizing cholesterol:phospholipid vesicles and might also be important in the regulatory process of bile lipid secretion. In order to study the factors influencing bile secretion, the biliary secretion rates of bile lipids and APF were experimentally modulated in perfused rat liver (PRL) and HepG2 cells. As expected, dexamethasone induced an increase in the biliary secretion rate of bile salts (BS) in the two models (PRL: 34 up to 67 nmol/l/min/g liver; HepG2 cells: 234% vs. 100% in controls). The bile secretion rates for phospholipids (PRL: from 5 down to 1.5 nmol/l/min/g liver; HepG2 cells: 93 vs. 100% in controls) and APF (PRL: from 0.34 down to 0.12 µg/l/min/g liver; cells: 86 vs. 100% in controls) rapidly decreased independently from those of BS. The data from experimental cell models supplemented with linoleic acid indicated a correlation between the BS and APF levels (APF: 71 and 63%; BS: 161 and 197% vs. 100% in controls). The phospholipid level was regulated independently from that of APF and BS and increased (106 and 111% vs. 100% in controls), while Ch remained nevertheless unchanged. Our data showed that dexamethasone induced changes in bile and that linoleic acid clearly impaired the regulation exerted by the dexamethasone on bile lipids.

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“…Phospholipids (PL) [13], bile salts [14] and cholesterol [15] were assayed by a semiautomatic colorimetric method. Activity of (3-glucuronidase de rived from lysosomal origin [16] was assayed in bile using the Sigma dosage kit.…”

Section: Assaysmentioning

confidence: 99%

Metabolism of Low- and High-Density-Lipoprotein-Free Cholesterol in Rats Fed High-Fat Diets

Chanussot¹,

Esnault-Dupuy²,

Martigne³

et al. 1988

Ann Nutr Metab

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The regulating process of cholesterol in the liver was studied in relation to its exogenous contribution in the rats fed high-fat (28%) high-cholesterol (1.2%) diets rich in saturated (S) fat (lard) or polyunsaturated (PU) fat (corn oil). Accordingly, the fate of ¹⁴C free cholesterol originating from high- or low-density lipoproteins (LDL) was examined in the biliary, hepatic and plasmatic lipids, as well as the activity of two key enzymes in the metabolism of lipoproteins: lipoprotein lipase (LPL) and lecithin cholesterol acyl transferase (LCAT). The LPL activity increased in the S diet, in comparison to the PU diet or to a low fat (6 %) control (C) diet and the LCAT activity increased but not significantly in the PU diet. In bile the secretion of ¹⁴C-cholesterol and ¹⁴C-bile salts originating from ¹⁴C-cholesterol-HDL increased in the S diet compared to the PU diet and a C diet [previous results]. S and PU diets increased to the same extent the hepatic storage of ¹⁴C-esterified cholesterol originating from LDL, compared to the C diet. This cholesterol would contribute to a greater extent to the hepatic synthesis of the lipoproteins destined for the plasma in the case of the S diet than that of PU diet. These results may be explained by the adaptation of hepatic acyl cholesterol acyl transferase and cholesterolesterase to both high-fat-diet enzymes acting simultaneously on the two free and esterfied cholesterol compartments. It resulted in an important redistribution of the cholesterol of these two compartments between plasma, bile and liver.

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Technique de dosage automatique de l'orthophosphate de grande fiabilité

Cited by 72 publications

References 6 publications

Intestinal Phospholipase, a Novel Enzyme

Intestinal Phospholipase, a Novel Enzyme

Effects of Dexamethasone and Linoleic Acid on Hepatic Secretion of Biliary Lipids and Anionic Polypeptide Factor: In vivo and in vitro Studies

Metabolism of Low- and High-Density-Lipoprotein-Free Cholesterol in Rats Fed High-Fat Diets

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