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Query: UMLS:C0392674 (exhaustion)
 13,658 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The availability of iron is critical in low-birthweight infants. We followed a group of small preterm infants without iron supplementation who were either exclusively breast-fed or weaned early to industrial infant milk formula or home-prepared cow's milk formula. The gain of iron was compared within the milk groups on the basis of hemoglobin and serum ferritin concentrations at the ages of 3 and 4 mth when only trace amounts of solid foods had been given. Contrary to the reports on term infants we found unsupplemented proprietary infant milk formula and breast milk similar as a source of iron. It is possible that there is no major inhibition of iron absorption from any milk during the time of simultaneously occurring accelerated erythropoiesis and exhaustion of iron stores in preterm infants. The apparent inferiority of cow's milk could be due to increased intestinal loss of blood.
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PMID:Iron gain in low-birthweight infants: role of milk feeding. 57 31

Knowledge of disturbancies of iron utilization has been considerably extended by histochemical-ultrastructural findings and the results of immunoradiometric assays for serum ferritin. -- In chronic anaemia due to infections or neoplastic diseases hyposideraemia and normal unsaturated iron binding capacity were associated with increased iron retention in macrophages and slightly to highly increased serum ferritin (500--4000 ng/ml). -- 117 patients with sideroblastic anaemia formed a heterogenous group of diverse aetiology. The iron granules of ringed sideroblasts contained nonferritin iron in mitochondria. At diagnosis, a normal iron status was found in single cases. More frequently, praelatent and latent iron overload with ferritin levels up to more than 2000 ng/ml were observed. Manifest iron overload with tissue damage was mostly the result of numerous transfusions (ferritin 4700 bis 9500 ng/ml). -- After i.v. application of colloidal iron endothelial siderosis was a regular finding. The typical uniform granules representing nonferritin-iron in lysosomes disappeared in the course of 1--3 years completely. In contrast, the colloidal iron taken up simultaneously by the macrophages was rapidly transformed into ferritin and easily used up for haemoglobin synthesis when required. The corresponding increase of serum ferritin up to maximal 4000 mg/ml was dose related. Continued blood losses lead to residual endothelial siderosis after exhaustion of macrophageal iron and recurrence of iron deficiency anaemia. The serum ferritin fell to low levels (0--12 ng/ml) as observed in untreated cases.
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PMID:[Disturbancies of iron utilization: chronic anaemia, sideroblastic anaemia, and residual endothelial siderosis (author's transl)]. 73 33

The experimental evidence relating to the hypothesis of finite cellular life is reviewed. It is emphasized that even if somatic cell production were limited its total potential would have to be vast to provide for extensive cellular regeneration. The actual limit of reproductive cell life would therefore not likely be reached in a normal life-span. It is proposed to test the hypothesis by deliberate exhaustion of stem-cell reserve, and iron-55 cytocide is described as an experimental system that might be applicable.
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PMID:Hayflick's hypothesis: an approach to in vivo testing. 108 46

To determine the effects of depleted iron stores on endurance performance and blood lactate concentration, eight active women with normal (> 26 ng/ml) and eight with low (< 12 ng/ml) plasma ferritin concentrations were studied while performing a VO2max and an endurance test (80% VO2max) on a cycle ergometer. The low ferritin group had significantly lower serum iron concentration and transferrin saturation and higher TIBC than the normal ferritin group. Mean VO2max was not significantly different between groups. No significant difference was found in total time to exhaustion during the endurance test for low (23.2 min) and normal (27.0 min) ferritin groups; however, the normal ferritin group exercised 14% longer. Blood lactate concentrations following the VO2max and endurance test did not differ significantly between groups. Food diaries revealed lower daily absorbable iron intake by the low ferritin group compared to the normal ferritin group. Ferritin concentration was significantly related to absorbable iron (r = .72) and total iron (r = .70) intake. The results suggest that women with depleted iron stores who are not anemic may have less endurance, but do not have higher blood lactate during exercise than women with normal iron stores.
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PMID:Effects of low ferritin concentration on endurance performance. 129 7

The influences of iron deficiency on erythrocyte spanning membrane proteins, band 3 protein and Na(+)-K(+)-ATPase, were studied in the growing rats with iron deficient anemia. The main findings were (1) reduction of band 3 and increment of band 4.1 protein. (2) diminished rate constant of pyruvate-chloride exchange (Kp:Cl.h-1) of the erythrocytes and (3) significant decrease of Na(+)-K(+)-ATPase activity only at the early stage of iron exhaustion. In addition, there was a significant negative correlation between Kp:Cl.h-1 and Na(+)-K(+)-ATPase activity both in iron deficient rats and in the controls. It is suggested that the composition and function of the erythrocyte spanning-membrane proteins for ion exchange could be affected by iron deficiency.
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PMID:Abnormalities of ion-exchange proteins of the red cell membrane in iron deficiency anemia. 131 72

The iron uptake mechanisms of enteropathogenic Escherichia coli (EPEC) were examined and compared with those of control E. coli strains. The incidence of aerobactin production was similar (39% and 37% respectively) in the two groups. The quantities of enterochelin produced by aerobactin-negative EPEC and control strains were similar, as were the quantities of enterochelin produced by aerobactin-positive EPEC and control strains. The ability to use haem or haemoglobin as an iron source in an iron-restricted environment was found in 80.4% and 60.8% of EPEC strains respectively, and in 76.6% and 56.6% of control E. coli strains. The ability of E. coli strains to use these compounds was not related to the production of enterochelin or aerobactin or to the production of haemolysins, and may be an important characteristic of bowel organisms. When growing in an iron-limited environment, the iron contained in haemoglobin was used in preference to ovotransferrin-bound iron. During periods of haemoglobin-stimulated growth, the enterochelin uptake system was shown to be fully expressed and may be involved in transport of haemoglobin-derived iron into the cell. Uptake of ovotransferrin-bound iron took place immediately upon exhaustion of haemoglobin-derived iron. The ability to use iron derived from haem compounds represents an alternative iron uptake mechanism for organisms growing in an iron-limited environment and allows greater flexibility during growth in vivo.
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PMID:The iron uptake mechanisms of enteropathogenic Escherichia coli: the use of haem and haemoglobin during growth in an iron-limited environment. 138 31

The purpose of this investigation was to examine the effects of oral iron supplementation on endurance performance in initially iron-depleted, nonanemic female distance runners. Eighteen iron-depleted (serum ferritin less than 20 ng.ml-1, hemoglobin greater than or equal to 12 g.dl-1) women (22-39 yr) performed a VO2max test and an endurance run to exhaustion. Subjects were pair-matched on the basis of endurance time and then randomly assigned to an iron supplement or a placebo group. Following supplementation, the iron group had a significantly higher (P = 0.03) mean serum ferritin concentration (23.4 vs 15.7 ng.ml-1) and lower (P = 0.04) mean total iron-binding capacity than the placebo group. Both groups increased their time to exhaustion (25.5% and 22.2% for the iron and placebo groups, respectively) but were not significantly different (P = 0.72) from each other. There were also no differences (P greater than 0.05) between the groups with respect to lactate concentrations and physiological measures taken during the two exercise tests. The results of this study suggest that 8 wk of oral iron supplementation improves iron status in iron-depleted female distance runners, but does not enhance endurance capacity.
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PMID:Effect of iron supplementation on endurance capacity in iron-depleted female runners. 150 68

A multicentre study was carried out in a sample population of healthy volunteers in order to assess the usefulness of assaying serum ferritin to monitor the extent of reserves in subjects with a risk of iron deficiency. A total of 317 subjects were included in the study. Ninety-nine were children with a mean age of 19 months, 121 were adolescents with a mean age of 18 years and 7 months, and 97 were women with a mean age of 28 years and 9 months. Levels of serum ferritin below the normal minimum levels for each age bracket, an indication of the exhaustion of the body's reserves, were found in 29% of children, 32.2% of adolescents and 27.8% of women. This study therefore confirm the frequent onset, even in our modern society, of iron-deficient states at particular times of life and that these are easily overlooked. The measurements of serum ferritin levels, in addition to being a confirmatory test in cases of suspected sideropenic anemia, has the peculiar characteristic of being the only test able to identify risk subjects before they become symptomatic. This enables rapid treatment to be commenced or better, efficient prevention.
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PMID:[Multicenter study of serum ferritin assay for the surveillance of subjects at risk of iron deficiency]. 194 3

Initial rates of ferrous iron transport into Bifidobacterium bifidum var. pennsylvanicus were measured at low and high iron concentrations. The low affinity system (LAFIUS) had an apparent Km of 167 microM, the high affinity system (HAFIUS) had a Km of 50 microM. Iron removal from preloaded bifidobacteria revealed the existence of a labile and an inert iron pool in the bacterial cells. Iron uptake by the bifidobacteria was associated with lactate production, though lactate production could continue without iron uptake. Cessation of iron uptake and lactate production was not because of an exhaustion of any nutrient nor the accumulation of fermentation end products in the medium. It was apparently the result of an inactivation of the cellular enzyme machinery without replacing it through normal biosynthetic processes.
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PMID:Transport of ferrous iron and lactate production in Bifidobacterium bifidum var. pennsylvanicus. 248 52

Serum ferritin levels were determined in 170 healthy Norwegian women (18-48 y, median age 36 y) including 23 blood donors. Exhausted iron stores, defined by serum ferritin levels less than 17 micrograms/l, were found in 21.8% of the non-donors, and in 30.4% of the donors. Women with serum ferritin levels less than or equal to 20 micrograms/l participated in a bioavailability study. They were randomized to one of three groups and given one of three different low dose iron supplements (18-20 mg iron per day) for six months. One of the supplements contained heme iron and non-heme iron, the other two contained non-heme iron only. Mean serum ferritin increase was significant for two of the supplements, the one containing heme iron giving the best result. All the supplements resulted in a significant decrease in TIBC.
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PMID:[Women and iron deficiency--a problem? Iron levels in a group of fertile Norwegian women and the bioavailability of 3 low-dose iron supplements in women with low iron stores]. 266 80


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