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Query: UMLS:C0240066 (iron deficiency)
 7,156 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

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

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

The effect of iron deficiency on work capacity was studied in groups of rats that had received diets with iron contents ranging between 9 and 50 mg/kg diet from 3 to 6 wk of age. Maximal O2 consumption (VO2max) declined only 16% with a decrease in hemoglobin (Hb) from 14 to 8 g/dl and fell sharply only below a Hb of 7 g/dl. Duration until exhaustion in a treadmill exercise of submaximal intensity (endurance) showed no significant depression between a Hb of 14 and 10 g/dl. However, endurance declined abruptly by 73% between a Hb of 10 and 8 g/dl. The VO2max results are in accord with known compensatory mechanisms that help to maintain delivery of O2 to tissues until anemia becomes severe. The sharp fall in endurance with relatively mild iron deficiency suggests a lack of similarly effective compensations for decreased oxidative capacity of muscle.
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PMID:Work performance in iron deficiency of increasing severity. 298 75

Confounding influences of varying fat, protein, and carbohydrate (CHO) levels, training habits, and lifestyle patterns make the interpretation of specific influences of the diet on endurance performance unclear. In general, exhaustion during prolonged, hard endurance exercise is tied to low muscle glycogen stores. Athletes in heavy training are urged to consume 70% of calories as CHO to maximize body CHO stores. A deemphasis in animal products with an emphasis in high-CHO plant foods would facilitate athletes in conforming to nutritional recommendations. Some female athletes may increase their risk of iron deficiency and/or amenorrhea if a restrictive vegetarian diet is adopted. In general, the high-CHO nature of the vegetarian diet can help the endurance athlete in heavy training maximize body glycogen stores and thus the ability to perform. The balanced vegetarian diet provides the athlete with added reduction in coronary risk factors while meeting all known nutritional needs.
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PMID:Vegetarian dietary practices and endurance performance. 304 4

The purpose of the present study was to evaluate the effects of iron deficiency on enzyme activities and endurance. Iron deficiency was induced in 9 healthy male subjects by repeated venesections. After a period of 9 wk (range, 8-11 wk) when the subjects had become iron deficient as defined by laboratory parameters, blood was retransfused to reestablish the control hemoglobin concentration. In this state it was possible to evaluate the effect of iron deficiency isolated from anemia. In samples secured by muscle biopsies, glycolytic, oxidative, and iron depending enzymes were analyzed in the control (C) and anemic (A) states and after retransfusion (R). There were no significant changes in the maximal activities of any of the enzymes studied. The capillary/fiber ratio remained unchanged between C (1.92) and R (1.94). Times to exhaustion on treadmill tests were 49 min, 11 s in C, 26 min, 33 s in A, and 52 min, 3 s in R. Vo2max was 4.55 1 X min-1 in C, 3.74 1 X min-1 in A, and 4.45 1 X min-1 in R. An artificially induced iron deficiency defined by conventional laboratory parameters did not affect endurance when transfusion of red blood cells was performed in order to exclude the influence of a low hemoglobin concentration. A 4-wk period of severely depleted or absent tissue iron stores did not affect the maximal activities of various enzymes in human skeletal muscle.
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PMID:Effects of iron deficiency on endurance and muscle enzyme activity in man. 370 42

Three weeks of dietary iron deficiency in weanling rats resulted in anemia (Hb, 3.9 vs. 14.2 g/dl in controls) and decreased oxidative capacities of skeletal muscle (as much as 90% below control values). Whole-animal maximal O2 consumption (VO2max), measured in a brief treadmill run of progressively increasing work load, was approximately 50% lower for iron-deficient rats than for controls, and maximal endurance capacity (time to exhaustion in a separate treadmill run at a constant, sub-Vo2max work load) was 90% lower for iron-deficient rats than for controls. Exchange transfusion, with packed erythrocytes or plasma, was used to adjust Hb to an intermediate concentration of approximately 9.5 g/dl in both iron-deficient and and control rats. This procedure corrected the Vo2max of iron-deficient rats to within 15% of control values, whereas endurance capacity showed no improvement. Our experimental dissociation of Vo2max and endurance capacity provides further evidence that Vo2max is not the sole determinant of endurance. We propose that defects in Vo2max during iron deficiency result primarily from diminished O2 delivery, whereas decreased endurance capacity reflects impaired muscle mitochondrial function.
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PMID:Distinguishing effects of anemia and muscle iron deficiency on exercise bioenergetics in the rat. 674 15

We studied the effect of 2 weeks of iron therapy on exercise performance and exercise-induced lactate production in trained women athletes: six control subjects with normal parameters of iron status and nine with mild iron-deficiency anemia defined by low Fe/TIBC, ferritin, and minimally decreased Hgb values. Iron therapy improved the abnormal measures of iron status and low Hgb in the second group to normal. Exercise performance in a progressive work-exercise protocol on a bicycle ergometer to exhaustion was unchanged after iron therapy in both groups; however, blood lactate levels at maximum exercise in the iron-deficient group decreased significantly from 10.3 +/- 0.6 mmol/L before therapy to 8.42 +/- 0.7 after therapy (p less than 0.03). The control subjects did not significantly alter lactate levels after maximal exercise on iron compared to placebo: 8.3 +/- 0.8 mmol/L vs. 8.5 +/- 0.7. Although there was not a significant difference in maximum exercise performance after iron therapy, these data support animal experiments implying that iron may play a role in oxidative metabolism and that minimal decreases in Hgb may impair arterial oxygen content enough to affect aerobic metabolism. In addition, these findings may have important implications for competitive women athletes in whom mild iron deficiency may go unnoticed.
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PMID:Iron repletion decreases maximal exercise lactate concentrations in female athletes with minimal iron-deficiency anemia. 686 76

Determination of serum ferritin is an important means of assessing body iron stores. Trace amounts of ferritin normally present in serum are detectable by sensitive radioimmunoassay techniques or an enzyme immunoassay procedure. Ferritin normally accounts for no more than a very small fraction of the total iron in serum, but generally maintains a stable concentration that is proportional to the much larger pool of storage iron in tissues. The serum ferritin assay, in contrast to other measurements of iron status such as hemoglobin, serum iron and iron-binding capacity, can distinguish differences in iron stores within the physiological range. In iron deficiency anemia, the concentration is below 10 ng per ml. Increased concentrations (above 200 ng per ml) are found in conditions with increased iron stores. The information it provides is similar to that obtained from bone-marrow aspirates stained for iron. In contrast to the percent transferrin-saturation and concentration of erythrocyte protoporphyrin, ferritin concentrations become abnormal before exhaustion of mobilizable iron stores and before the onset of anemia. Serum ferritin also provides a practical means of assessing new programs of iron supplementation, since it reflects various degrees of iron deficiency and overload.
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PMID:The measurement and interpretation of serum ferritin. 700 32

We hypothesized that augmented responses of glucoregulatory hormones in iron deficiency would enhance liver and muscle glycogenolysis, leading to increased gluconeogenic precursor (lactate) supply and upregulation of hepatic gluconeogenesis. Female weanling rats were randomly placed on either a mildly iron-deficient (-Fe; 15 mg Fe/kg diet) or an iron-sufficient (+Fe; 50 mg Fe/kg diet) diet for 4 wk and studied at rest and during exhaustive treadmill running. Hemoglobin was 9.0 +/- 0.2 and 13.1 +/- 0.3 g/dl in -Fe and +Fe, respectively, after 3.5 wk of dietary iron deficiency. Arterial plasma epinephrine (Epi), norepinephrine (NE), adrenocorticotropic hormone (ACTH), corticosterone, insulin, and glucagon levels were similar at rest in both groups, as were liver, gastrocnemius, and superficial and deep vastus medialis glycogen levels. Liver and kidney phosphoenolpyruvate carboxykinase (PEPCK) activities were similar in both groups. Maximum O2 consumption was decreased (22%) in -Fe. Respiratory exchange ratio (CO2 production/O2 consumption) was unaffected at rest but increased at maximum O2 consumption in -Fe. Time to exhaustion during a standardized running test (13.4 m/min, 0% grade) was decreased 45% in -Fe (63 +/- 5 vs. 116 +/- 10 min). During exercise, euglycemia was maintained in both groups, but blood lactate was elevated in -Fe. The mean net glycogen utilization during exercise was increased in liver (43%), soleus (33%), and superficial vastus medialis (106%) and decreased in the gastrocnemius (36%) in -Fe. Liver and kidney PEPCK activities were increased similarly at exhaustion in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Augmented glucoregulatory hormone concentrations during exhausting exercise in mildly iron-deficient rats. 823 58

Pseudomonas aeruginosa PAO1 was recently found to exhibit two remarkable physiological responses to oxidative stress: (1) a strong reduction in the efficiency of oxygen transfer from the gas phase into the liquid phase, thus causing oxygen limitation in the culture and (2) formation of a clear polysaccharide capsule on the cell surface. In this work, it has been shown that the iron concentration in the culture plays a crucial role in evoking these phenomena. The physiological responses of two P. aeruginosa PAO1 isolates (NCCB 2452 and ATCC 15692) were examined in growth media with varied iron concentrations. In a computer-controlled bioreactor cultivation system for controlled dissolved oxygen tension (pO2), a strong correlation between the exhaustion of iron and the onset of oxygen limitation was observed. The oxygen transfer rate of the culture, characterized by the volumetric oxygen transfer coefficient, kLa, significantly decreased under iron-limited conditions. The formation of alginate and capsule was more strongly affected by iron concentration than by oxygen concentration. The reduction of the oxygen transfer rate and the subsequent oxygen limitation triggered by iron deficiency may represent a new and efficient way for P. aeruginosa PAO1 to adapt to growth conditions of iron limitation. Furthermore, the secretion of proteins into the culture medium was strongly enhanced by iron limitation. The formation of the virulence factor elastase and the iron chelators pyoverdine and pyochelin also significantly increased under iron-limited conditions. These results have implications for lung infection of cystic fibrosis patients by P. aeruginosa in view of the prevalence of iron limitation at the site of infection and the respiratory failure leading to death.
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PMID:Iron deficiency leads to inhibition of oxygen transfer and enhanced formation of virulence factors in cultures of Pseudomonas aeruginosa PAO1. 1294 86


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