Mineral availability and techniques for its measurement

Thompson, A.

doi:10.1079/pns19650014

Cited by 23 publications

(7 citation statements)

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“…the 'comparative balance method', the 'dual tracer' or 'double isotope' technique, methods based on computerized 'compartment analysis' and the 'isotope-dilution technique' (e.g. AUBERT et al 1963;THOMPSON 1965;BELSHAW et al 1974;GIBSON et al 1988). Among these methods, the isotope-dilution technique, in particular, comprises direct and quantitative measurements of mineral fluxes and provides robust estimates of endogenous faecal excretions as has been shown for a series of macrominerals and trace elements (WEIGAND and KIRCHGESSNER 1976a,b;WEIGAND et al 1986a,b;KREUZER and KIRCHGESSNER 1991;REUBER et al 1993;KIRCHGESSNER et al 1994;WINDISCH and KIRCHGESSNER 1994;WINDISCH et al 1997;GABLER et al 1997).…”

Section: Introductionmentioning

confidence: 99%

Isotope‐dilution technique for determination of endogenous faecal excretion and true absorption of iodine in ¹²⁵I labelled rats

Windisch¹,

He²,

Kirchgeßner³

1999

Animal Physiology Nutrition

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Introduction In studies on the quantitative mineral metabolism the separation of total faecal mineral excretion into the fraction of dietary and of endogenous origin is often a methodical barrier. Both components cannot be distinguished by standard chemical procedures. But their separation is essential to the quantification of the mineral flux from the diet into the organism and back from tissues into the faecal excretion as it is necessary for example to quantify the bioavailability of dietary mineral sources (K irchgessner et al. 1993). For this purpose, the use of isotopes is an appropriate means. During the last decades, several techniques employing radioactive or stable isotopes have been developed, e.g. the ‘comparative balance method’, the ‘dual tracer’ or ‘double isotope’ technique, methods based on computerized ‘compartment analysis’ and the ‘isotope‐dilution technique’ (e.g. A ubert et al. 1963; T hompson 1965; B elshaw et al. 1974; G ibson et al. 1988). Among these methods, the isotope‐dilution technique, in particular, comprises direct and quantitative measurements of mineral fluxes and provides robust estimates of endogenous faecal excretions as has been shown for a series of macrominerals and trace elements (W eigand and K irchgessner 1976a,b; W eigand et al. 1986a,b; K reuzer and K irchgessner 1991; R euber et al. 1993; K irchgessner et al. 1994; W indisch and K irchgessner 1994; W indisch et al. 1997; G abler et al. 1997). For iodine however, there is no appropriate isotope method available. Therefore, the present experiment was designed to establish the isotope‐dilution technique for iodine. The isotope‐dilution technique is based on a single parenteral injection or a long‐term oral administration of the tracer (W indisch and K irchgessner 1994). After the labelling procedure, all tracer that appears in the faeces is of endogenous origin. The calculation from the quantity of tracer recovered in the faeces to the total amount of endogenous faecal excretion of the respective element is performed by the use of a reference tissue from which the endogenous excretion originates or which is at least in very close physiological relationship to the endogenous excretion. Using 125I as tracer the total amount of endogenous faecal iodine is calculated as follows: Endogenous faecal iodine (ng/day) = Afaeces/SAreference tissueAfaeces = 125I activity in the faeces (Bq/day)SAreference tissue = specific 125I activity of the reference tissue (Bq 125I per ng of total iodine)True absorption of dietary iodine (ng/day) = Iodine intake – iodine in faeces (total – endogenous)In total, the present methodological study had to focus on two major aspects. Since the administered tracer needs time to reach steady‐state kinetics within the excretory pool of iodine it was to be clarified at first, from which day after a single 125I administration does the faecal 125I excretion correctly represent the total endogenous excretion quantitatively. ...

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Section: Introductionmentioning

confidence: 99%

Isotope‐dilution technique for determination of endogenous faecal excretion and true absorption of iodine in ¹²⁵I labelled rats

Windisch¹,

He²,

Kirchgeßner³

1999

Animal Physiology Nutrition

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“…Hence, calculations were based upon the isotope VOl. 20 Endogenous Ca and P excretion 797 dilution principle which has been adequately described by Kleiber, Smith, Ralston & Black (1951) and by Thompson (1965). The formula used to calculate metabolic faecal excretion is as follows:…”

Section: E X P E R I M E N T a Lmentioning

confidence: 99%

The effects of phosphorus depletion, and of calcium and phosphorus intake, on the endogenous excretion of these elements by sheep

1966

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I . Injections of and 45Ca were used to study the influence of phosphorus depletion and repletion on the rates of endogenous calcium and P excretion in fifteen P-depleted and eighteen control sheep. 2. When given adequate P, there was a marked increase in the rate of excretion of metabolic faecal P in sheep which previously had been depleted. In control sheep a decrease was found in metabolic faecal P excretion with a diet deficient in P. 3. From the values for metabolic faecal P an indirect estimate of total intestinal secretion was made. The estimate was found to be in approximate agreement with values derived from published values for total daily digestive secretions in sheep. 4. The estimated rates of secretion of intestinal P suggest that after the addition of P to the diet the changes in the rate of excretion of metabolic faecal P in P-depleted sheep were the result of a decreased reabsorption of intestinally secreted P rather than of a change in the rate of secretion into the intestine. After a diet low in this element the decrease in metabolic faecal P excretion by control sheep appeared to be the result of a decreased rate of intestinal P secretion. 5 . The possible significance of changes in metabolic faecal P excretion in relation to body P homoeostasis in the ruminant animal is discussed.The physiological significance of endogenous faecal calcium and phosphorus excretion is not clear. Moreover, the question of whether there is a controlled secretion of these elements into the intestinal tract, regulating their concentration in the body, has been disputed for years. The current general consensus, as indicated in recent reviews (Hill, 1963 ;Irving, 1964), is that the excretions of Ca and P are not controlled, but instead represent a loss of these elements in the digestive juices and turnover of the intestinal mucosa.

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“…In the present study, the isotope dilution technique and the comparative isotope balance procedure were compared for determining true absorption of dietary manganese. The assumptions to be made in the application of these two procedures have been reviewed already (COMAR et al 1953;THOMPSON 1965). Major advantages of the isotope dilution technique are that just one group of animals is needed and that it is also suitable for availability studies.…”

Section: Discussionmentioning

confidence: 99%

“…The major underlying assumptions for computing true absorption by the comparative isotope balance are 1) that the radioisotope added to the diet is absorbed to an equal percentage as the stable element in the diet and 2) that the absorbed isotope is excreted in feces from endogenous sources to the same extent as the isotope administered parenterally (THOMPSON 1965 Calculation of endogenous fecal manganese follows from the relationships given by Eqs. (2a) to (3b), using the conventional Mn balance data.…”

Section: Comparative Isotope Balance and Retentionmentioning

confidence: 99%

Comparison of Isotope Techniques for Determining True Absorption of Dietary Manganese in Growing Rats¹

Weigand

Kirchgeßner

Helbig

1986

Animal Physiology Nutrition

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Zusammenfassung Vergleich von Isotopenmethoden zur Bestimmung der wahren Absorption von Nahrungsmangan bei der wachsenden Ratte Ziel der Untersuchung war ein Vergleich zwischen den Methoden der Isotopenverdünnung (ID) und der komparativen Isotopenbilanz (CB) zur bestimmung der wahren Absorption von Nahrungsmangan. Dazu wurde eine Diät mit 11,9 mg Mn je kg Trockenmasse an 20 männliche Ratten ab dem Zeitpunkt der Entwöhnung verfüttert. Bei einer mittleren Lebendmasse von 60 g erhielten je 10 Tiere eine 54Mn‐Dosis entweder durch eine i.m. Injektion (Gruppe GP) oder oral über die Diät (Gruppe GO). Die mittlere 54Mn‐Retention nach 4, 8, 12 und 16 Tagen betrug in der Gruppe GP 46,0; 28,6; 22,0 bzw. 18,6% der Dosis im Vergleich zu 9,8; 4,9; 3,2 bzw. 2,6% in der Gruppe GO. Urin war mit höchstens 0,2% an der gesamten 54Mn‐Ausscheidung beteiligt. Die spezifische Aktivität des Mangans im Serum war 16 Tage nach der 54Mn‐Applikation innerhalb beider Gruppen etwa 30% höher als in der Leber und deutlich niedriger als in anderen inneren Organen, im Skelettmuskel oder im Schlachtkörper. Unter der Annahme, daß die spezifische Aktivität des Serummangans 16 Tage nach der 54Mn‐Injektion im Durchschnitt für die Markierung des endogenen Mangans im Kot vom Tag 9–16 repräsentativ ist, wurden die wahre Absorption und endogene fäkale Exkretion des Mangans nach der ID‐Methode in der Gruppe GP mit 22,2 bzw. 8,0% und in der Gruppe GO mit 20,2 bzw. 10,0% der Mn‐Aufnahme ermittelt. Die Bestimmung dieser beiden Parameter nach der CB‐Methode anhand der prozentualen 54Mn‐Exkretion innerhalb von vier Tagen nach der Dosierung ergab 21,3 bzw. 11,5% der Mn‐Aufnahme, so daß mit den Werten nach dem ID‐Verfahren gute übereinstimmung bestand. Die Anwendung der CB‐Methode an die Daten der 54Mn‐Retention nach 8, 12 oder 16 Tagen führte dagegen zu deutlich niedrigeren Werten.

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Mineral availability and techniques for its measurement

Cited by 23 publications

References 31 publications

Isotope‐dilution technique for determination of endogenous faecal excretion and true absorption of iodine in ¹²⁵I labelled rats

Isotope‐dilution technique for determination of endogenous faecal excretion and true absorption of iodine in ¹²⁵I labelled rats

The effects of phosphorus depletion, and of calcium and phosphorus intake, on the endogenous excretion of these elements by sheep

Comparison of Isotope Techniques for Determining True Absorption of Dietary Manganese in Growing Rats¹

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Mineral availability and techniques for its measurement

Cited by 23 publications

References 31 publications

Isotope‐dilution technique for determination of endogenous faecal excretion and true absorption of iodine in 125I labelled rats

Isotope‐dilution technique for determination of endogenous faecal excretion and true absorption of iodine in 125I labelled rats

The effects of phosphorus depletion, and of calcium and phosphorus intake, on the endogenous excretion of these elements by sheep

Comparison of Isotope Techniques for Determining True Absorption of Dietary Manganese in Growing Rats1

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Isotope‐dilution technique for determination of endogenous faecal excretion and true absorption of iodine in ¹²⁵I labelled rats

Isotope‐dilution technique for determination of endogenous faecal excretion and true absorption of iodine in ¹²⁵I labelled rats

Comparison of Isotope Techniques for Determining True Absorption of Dietary Manganese in Growing Rats¹