The I131 Labeled Triolein Absorption Test: Reproducibility and Factors Affecting Blood Levels

Wc, Chears; Bh, McCRAW; Mp, Tyor; Jm, Ruffin

doi:10.1097/00007611-195804000-00004

Cited by 14 publications

(2 citation statements)

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“…and 37°C. This confirms the findings of Chears, McCraw, Tyor, and Ruffin (1958), and demonstrates that RIT for clinical use may be stored as an emulsion. In gastric juice free 1131 was not released from RIT, indicating that the bond is stable in the stomach.…”

Section: Stability Of the Bond In Watersupporting

confidence: 87%

The stability of the radiotriolein bond in intestinal secretions

Cox¹,

Hinchliffe²

1961

Gut

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SYNOPSISThe radiotriolein test has been reported to be unreliable in the diagnosis of steatorrhoea. A possible explanation is provided by these studies in which labelled triolein was incubated in human gastric juice, duodenal juice, and faeces; the bond was not stable on duodenal juice.Radio-iodinated triolein (RIT) has been widely used in the investigation of intestinal malabsorption. The method is essentially a tracer test in which a known dose of RIT is given by mouth and the percentage of the administered isotope appearing in the plasma or excreted in the faeces is measured. This provides an assessment of fat digestion and absorption by the alimentary tract.The reliability of the method was not seriously questioned until Pimparkar, Tulsky, Kalser, and Bockus (1960) reported a large series of cases tested by concurrent faecal chemical fat and faecal RIT measurements. Taking a daily faecal chemical fat excretion of over 7.0 g. as the criterion for steatorrhoea, they found that the RIT test failed to diagnose the condition in 25% of cases. In a personal series of 33 patients found to have steatorrhoea by the faecal chemical fat excretion, the RIT test failed in 50% (Cox, 1961). A possible explanation of these findings is that the radio-iodine label is unstable in the alimentary tract. Since the metabolic pathway of iodine differs from that of fat, instability of the RIT bond would clearly vitiate the test.Experimental testing of the RIT bond in intestinal secretions has been reported by Beres, Wenger, and Kirsner (1957) and by Balint, Pendower, and Ramsey (1960). The former group incubated RIT with gastric juice, pancreatic juice, and bile for one hour, and, by measuring the activity in the aqueous fraction after extraction with petroleum ether, they concluded that the bond was stable over the period of the experiment. Using a similar method, Balint and his colleagues incubated RIT in a wider range of media. Instability was not detected during four hours' incubation in gastric or duodenal secretions, but a small amount of free radio-iodine was liberated in faeces over a two-day period of incubation.The use of an anion exchange resin to determine the percentage of free 1131 in radio-iodinated lipids (Cox and Hinchliffe, 1961) offers a simple means of repeated testing of the stability of the bond, permits the behaviour of the bond to be followed over a long period of time, and allows a comparison of the characteristics of different batches of RIT. This paper reports the results of such a study. METHODThe experiments were conducted in the following way. The batch of RIT under test was emulsified with Tween 80 and water, and incubated with controls and intestinal secretions. Water at 20°C. and 37°C. served as controls. The intestinal secretions studied were gastric juice, duodenal juice, and faeces, each incubated at 37°C. Samples were taken from the incubation mixtures at intervals of 0, four, eight, 24, 48, 72, and 96

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Section: Stability Of the Bond In Watersupporting

confidence: 87%

The stability of the radiotriolein bond in intestinal secretions

Cox¹,

Hinchliffe²

1961

Gut

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“…It is clearly essential that the administered dose should not contain any significant proportion of free 1311. Two methods have been reported for the determination of free 1311 in radio-lipids; Chears, McCraw, Tyor, and Ruffin (1958) dialysed radio-iodinated triolein to separate free 131I from bound 131I; Beres, Wenger, and Kirsner (1957) and Balint, Pendower, and Ramsey (1960) dissolved it in a fat solvent and extracted free 1311 into water. These methods do not lend themselves to frequent and rapid determinations.…”

mentioning

confidence: 99%

A method for the determination of free¹³¹I in radio-iodinated lipids

Cox¹,

Hinchliffe²

1962

J Clin Pathol

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SYNOPSIS Experiments are described showing that an anion exchange resin may be used as a simple means of determining the amount of free radio-activity in emulsions of triolein and oleic acid labelled with 1311 in the form of 1311CI. In the case of radio-iodinated triolein no special modifications are necessary. With radio-iodinated oleic acid, the working solution is made up with an excess of unlabelled oleic acid emulsion to prevent uptake of bound radio-activity by the resin.Recovery experiments show the method to be approximately 90 % efficient, which is adequate when the radio-lipids are to be used for clinical purposes.In the last 10 years increasing use has been made of radio-iodinated lipids in the diagnosis of steatorrhoea and the investigation of related disorders. The materials used are radio-iodinated triolein and radio-iodinated oleic acid. A measured dose of the radio-lipid is given by mouth, and the percentage of the dose appearing in the plasma or excreted in the faeces is determined.

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