Iron absorption and transport?An update

Conrad, Marcel E.; Umbreit, Jay N.

doi:10.1002/1096-8652(200008)64:4<287::aid-ajh9>3.0.co;2-l

Cited by 222 publications

(140 citation statements)

References 65 publications

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“…In the intestinal lumen there is no transferrin, and transferrin receptors are lacking from the luminal surface. Intestinal cells have alternative forms of inorganic iron transport [1]. Iron is found naturally in two valance states, ferric (III) the most oxidized, and ferrous (II), the most reduced.…”

Section: Introductionmentioning

confidence: 99%

Localization of the iron transport proteins mobilferrin and DMT‐1 in the duodenum: The surprising role of mucin

et al. 2003

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There are two pathways for inorganic iron uptake in the intestine, the ferric pathway, mediated by the key protein mobilferrin, and the ferrous pathway, mediated by DMT-1. Previous studies reported that the amount of DMT-1 increased in the intestinal mucosa in iron deficiency and the increase was seen in the apical portion of the villus of the duodenal mucosa. Mobilferrin did not quantitatively increase but became localized at the cell membrane. However, studies on fresh tissue have not previously been performed and the localization to the microvillae has not been demonstrated. In order to more definitively localize these proteins immunofluorescent and electron microscopic studies were undertaken. Samples were also subjected to biochemical analysis and Western analysis. In iron-deficient animals both DMT-1 and Mobilferrin were concentrated in the apical surface of the villae. Electron microscopy revealed that the majority of this increase in the amount of these proteins near the luminal surface was due to increased binding of the proteins to mucin in vesicles near the surface. A significant portion of the iron transport proteins was localized in the goblet cells and outside the cell in the luminal mucin, as demonstrated by immunofluorescence, electron microscopy, and isolation of the mucin by cesium chloride gradient centrifugation and Western analysis. A new model for the transport of metal ions was suggested. The metal transport proteins travel from vesicles inside the cell out to the lumen mucin. This increases the surface area and allows a greater portion of the lumen contents to be exposed to the binding proteins. Once the metal is bound to the externalized protein it is internalized into the cell. This explains many of the unique properties of the iron-binding proteins and suggests that it may be a more general model for the absorption of other nutrients. Am. J. Hematol. 74:32-45, 2003.

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Section: Introductionmentioning

confidence: 99%

Localization of the iron transport proteins mobilferrin and DMT‐1 in the duodenum: The surprising role of mucin

et al. 2003

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“…La principal proteína trasportadora de Fe es la transferrina (Tf), que capta el hierro requerido desde el lumen intestinal y de los lugares de degradación de la hemoglobina (sistema monocito-macrófago) (15) . La Tf puede unir de manera reversible dos átomos de Fe…”

Section: Transporte De Hierro En La Circulaciónunclassified

“…A través de este mecanismo la célula puede detectar el estatus de Fe sistémico, induciendo regulación negativa de su captación vía DMT1 a nivel apical (15) . El receptor de transferrina (RTf), que media la captación de Fe celular, cumple un rol clave en la homeostasis del hierro.…”

Section: Receptor De Transferrinaunclassified

Biomarcadores del metabolismo y nutrición de hierro

Sermini¹,

Guerrero²,

Arredondo³

2017

Rev Peru Med Exp Salud Publica

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RESUMENLa anemia por deficiencia de hierro continúa siendo la deficiencia nutricional más abundante en el mundo, y son los lactantes, preescolares, mujeres en edad fértil y embarazadas los grupos de mayor susceptibilidad. Debido a esto es que se hace necesario el conocer los mecanismos de regulación de captación, transporte y absorción del metal a nivel celular, principalmente a nivel del enterocito y, una vez que el hierro entra a la circulación, conocer cuáles son los biomarcadores que permiten realizar un seguimiento del estatus del hierro corporal. En esta revisión mostramos, en primer lugar, cómo se regula la entrada de hierro a nivel de la célula del epitelio intestinal, mostrando las principales proteínas involucradas (transportadores de entrada y salida de hierro, oxido-reductasas, proteína de almacenamiento) y, para finalizar, hacemos un recuento de los principales biomarcadores del metabolismo de hierro una vez que este ha entrado y circula por el organismo. BIOMARKERS OF METABOLISM AND IRON NUTRITION ABSTRACTIron deficiency anemia is the most common nutritional deficiency worldwide, and the most susceptible groups are infants, preschoolers, women of childbearing age, and pregnant women. It is therefore essential to understand the mechanisms of regulation of iron uptake, transport, and absorption at the cellular level, particularly in enterocytes, and to identify blood biomarkers that allow the evaluation of iron status. This review describes how iron absorption is regulated by intestinal epithelial cells, the main proteins involved (iron transporters, oxidoreductases, storage proteins), and the main blood biomarkers of iron metabolism. INTRODUCCIÓN METABOLISMO DEL HIERROEl hierro es un mineral esencial para la vida debido a que participa en múltiples funciones enzimáticas involucradas tanto en el transporte de oxígeno, metabolismo energético y síntesis de ADN, entre otras (1) . El contenido normal de hierro en el organismo es de aproximadamente 4 g, de los cuales, 3 g forman parte de la hemoglobina, la mioglobina, las catalasas y otras enzimas respiratorias. El hierro almacenado corresponde a 0,5 g y, en su mayor parte, se encuentra depositado a nivel hepático (2) . A pesar de su gran importancia, el exceso de hierro se relaciona con morbilidad y mortalidad. Esto, debido a que puede producir daño celular por estrés oxidativo, mediante la generación de especies reactivas de oxigeno (ROS) a través de la reacción de Fenton, las cuales actúan sobre componentes biológicos como los lípidos, proteínas y ADN (3) , lo que determina que el metabolismo del hierro sea controlado por un potente sistema regulador. ABSORCIÓN DE FeEl hombre es capaz de reutilizar el hierro proveniente de la destrucción de los eritrocitos senescentes debido a la acción de los macrófagos del sistema retículo endotelial (4) . Además, del total de hierro que se moviliza diariamente, solo se pierde una pequeña proporción a través de las heces, orina, sudor y la descamación celular. Por lo que se requiere un pequeño aporte diario a travé...

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“…a slow-release formulation) and solubility of the particular iron salt can also influence the bioavailability. [12][13][14] In these cases, in vitro dissolution may be a more appropriate assessment method.…”

Section: Introductionmentioning

confidence: 99%

In Vitro Dissolution Profile of Two Commercially Available Iron Preparations

2012

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Background: Current scientific evidence indicates that anemia in pregnancy, regardless of severity, is associated with an increased risk of maternal and fetal mortality. There is little published information about the bioavailability and bioequivalence of formulations containing both iron and folic acid. However, in vitro dissolution studies can provide important information on the likely relative bioavailability of various formulations. Aim: The objective of our study was to compare the in vitro dissolution of two similar commercially available formulations of iron-and folic acid-containing supplements, Folifer Ò (Bialport -Produtos Farmaceˆuticos, S.A., Portugal) and Ferroliver Ò (SM Pharma c.a., Venezuela), in order to determine the in vitro availability of their iron content. Folifer Ò and Ferroliver Ò were chosen because they contained similar amounts of elemental iron. Methods: The amount of iron released from each tablet was evaluated over a 4-hour period in three dissolution media replicating gastric or intestinal juices with pH values ranging from 1.5 to 6.9. The samples were then titrated with a solution of cerium ammonium sulfate in order to calculate the amount of iron released in each specific pH condition. The percentage of dissolved iron was calculated as a cumulative frequency, using the percentage of dissolved iron at all timepoints. The dissolution similarity between the two commercially available formulations was evaluated using the e 2 statistic formula. Results: During a 4-hour dissolution test, Folifer Ò released 59.4 mg of iron compared with 48.5 mg released by Ferroliver Ò . The value obtained for the similarity factor, an indicator of likely bioequivalence, was 41. Conclusion: These data suggest that Folifer Ò releases more iron than Ferroliver Ò , and that the two formulations are not equivalent in vitro. The superior dissolution of ferrous sulfate with Folifer Ò compared with ferrous fumarate in Ferroliver Ò might be responsible for the observed difference.

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Iron absorption and transport?An update

Cited by 222 publications

References 65 publications

Localization of the iron transport proteins mobilferrin and DMT‐1 in the duodenum: The surprising role of mucin

Localization of the iron transport proteins mobilferrin and DMT‐1 in the duodenum: The surprising role of mucin

Biomarcadores del metabolismo y nutrición de hierro

In Vitro Dissolution Profile of Two Commercially Available Iron Preparations

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