Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P02794 (ferritin)
 17,525 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of oral iron supplementation on erythropoiesis was studied prospectively in 34 autologous blood donors. The subjects, all of whom were to undergo total hip surgery, had normal iron status at the start of the study. During the preoperative period, in which 4 units of blood were collected, 17 patients received oral iron supplementation with 287 mg of ferrous sulfate (105 mg of elemental iron/day), while 17 patients did not use any iron supplementation. Oral iron supplementation during the 4-week preoperative period lessened the decrease in ferritin levels after two phlebotomies. Neither the decrease in hemoglobin nor the increase in erythropoietin levels was influenced by iron supplementation. In both iron-supplemented and control patients, serum erythropoietin levels returned to initial values within a few days after surgery. In autologous blood donors with a normal iron status, the use of supplemental iron does not affect erythropoiesis and is insufficient to maintain iron stores.
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PMID:The effect of oral iron supplementation on erythropoiesis in autologous blood donors. 141 90

After fractionation of mitochondrion-free extracts of Xenopus laevis and Rana temporaria oocytes in sucrose gradients, a distinct peak of adenosine triphosphate (ATP)/guanosine triphosphate (GTP)-binding activity in the 50-70 S range has been detected. This substance has a boyant density in Cs2SO4 of 1.45 g/cm3. The nucleotide-binding substance has been purified to apparent homogenety. By means of electron microscopy, sodium dodecyl sulfate-electrophoresis and other methods it has been identified as ferritin.
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PMID:The main adenosine triphosphate-binding component of amphibian oocytes is ferritin. 156 27

While iron is essential for numerous intracellular processes, its critical role in DNA synthesis relates to the activity of the iron-containing M2 subunit of ribonucleotide reductase, the enzyme responsible for the synthesis of deoxyribonucleotides. Gallium, a metal which resembles iron with respect to transferrin (Tf) binding, cellular uptake by the Tf receptor and incorporation into ferritin, blocks the cellular uptake of iron and inhibits cell growth. Exposure of HL60 cells to Tf-gallium (Ga) results in decreased deoxyribonucleotide synthesis and a diminution in the electron spin resonance (ESR) spectroscopy signal of ribonucleotide reductase, findings consistent with inhibition of this enzyme. In the present study, Ga nitrate blocked the uptake of 59Fe by L1210 cells and inhibited their proliferation. The ribonucleotide reductase M2 subunit ESR signal in cell cytoplasmic extracts was markedly inhibited in Ga-treated cells; however, the signal was restored to normal within 10 min of exposure of these cytoplasmic extracts to ferrous ammonium sulfate. These results confirm that Ga inhibits DNA synthesis by specifically limiting the amount of intracellular iron needed for the activity of the M2 subunit of ribonucleotide reductase. Further studies utilizing HL60 cells made resistant to Ga showed that these cells were also more resistant to growth inhibition by an anti-Tf receptor monoclonal antibody and deferoxamine. Ga blocks cell growth through inhibition of iron-dependent DNA synthesis. Cells appear to overcome the effects of Ga through compensatory mechanisms involving cellular iron metabolism.
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PMID:Targeting iron-dependent DNA synthesis with gallium and transferrin-gallium. 164 76

Polycythemia in CAPD patients has been rarely described. Over an eight year period, 4 out of 123 CAPD patients (3%) were identified as having Hct values exceeding 50% for 1 month or longer. All of the 4 patients were insulin dependent diabetics (4/47 diabetic patients, 8.5%). Charts were reviewed on 3 of these 4 patients. Polycythemia developed after a mean of 21 +/- 7 months on peritoneal dialysis. Prior to the development of polycythemia, ferritin levels were low and ferrous sulfate therapy was begun at a time the Hct values were 36 to 40%. Erythropoietin levels were obtained in 2 patients, and were 22 U/L (Hct 51%) and less than 5 U/L (Hct 55%). Renal ultrasound failed to show renal masses or cysts. One patient had a plasma volume of 2.1 L (normal 2.4-3.2 L); another patient was clinically volume depleted. Complications during the period of polycythemia included gangrenous feet requiring amputation in 2 patients, CVA in 2 patients, and splenic infarct in 1 patient. One patient died of cerebral thrombosis. We conclude that polycythemia is uncommon in CAPD patients and occurs most often in diabetic patients. Volume depletion and iron therapy may play a role in its etiology. In this high risk group of patients polycythemia may contribute to vascular complications and should be avoided.
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PMID:Polycythemia in diabetic patients on CAPD. 168 Apr 62

The efficiency of semi-dry electrophoretic transfer after sodium dodecyl sulfate (SDS)-electrophoresis using PhastGel media was investigated in a model system using three isotope labelled proteins. To give a full picture of the blotting process the amount of protein present in the gel, membranes, and filter papers was determined after different transfer times. The influence of the transfer buffer, commonly used additives such as methanol and SDS, and several different immobilizing matrices was investigated. Soybean trypsin inhibitor, bovine serum albumin, and ferritin were used as model proteins to study the effect of size on transfer efficiency. Basically, all three stages of the blotting process decide the result; the elution of protein from the gel, the immobilization of protein to the membrane, and the loss of material from the membrane during transfer. A theoretical explanation for the observed poor binding to a second membrane is discussed. Our results show that the buffer composition has little influence on the efficiency of transfer from the gel, but can be significant to the binding capacity of the membrane. In all experiments performed, there was never one moment during the transfer when all protein was eluted from the gel and simultaneously still bound to the membrane. The highest recovery in the membrane was obtained at different time intervals for different proteins. This indicates that quantitative transfer procedures cannot be generalized. However, obtaining an optimal method for reliable quantification of a specific protein or group of proteins is possible. For general protein staining of nitrocellulose and polyvinylidene difluoride membranes, a highly sensitive silver staining method requiring only 15 min has been used.
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PMID:Important parameters in semi-dry electrophoretic transfer. 169 Jun 43

The intracellular location of membrane-associated (NiFe) and (NiFeSe) hydrogenases of Desulfovibrio vulgaris was determined using pre-embedding and post-embedding immunoelectron microscopic procedures. Polyclonal antisera directed against the purified (NiFe) and (NiFeSe) hydrogenases were raised in rabbits. One-day-old cultures of D. vulgaris, grown on a lactate/sulfate medium, were used for all experiments in these studies. For post-embedding labeling studies cells were fixed with 0.2% glutaraldehyde and 0.3% formaldehyde, dehydrated with methanol, and embedded in the low-temperature resin Lowicryl K4M. Our post-embedding studies using antibody-gold or protein-A-gold as electron-dense markers revealed the location of the two hydrogenases exclusively at the cell periphery; the precise membrane location was then demonstrated by pre-embedding labeling. Spheroplasts were incubated with the polyclonal antisera against (NiFe) and (NiFeSe) hydrogenase followed by ferritin-linked secondary antibodies prior to embedding and sectioning. The observed labeling pattern unequivocally revealed that the antigenic reactive sites of the (NiFe) hydrogenase are located in the near vicinity of the cytoplasmic membrane facing into the periplasmic space, whereas the (NiFeSe) hydrogenase is associated with the cytoplasmic side of the cytoplasmic membrane.
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PMID:Localization of membrane-associated (NiFe) and (NiFeSe) hydrogenases of Desulfovibrio vulgaris using immunoelectron microscopic procedures. 169 42

Studies were undertaken using human duodenal mucosa to determine whether it contained a counterpart to a newly identified iron-binding protein recently isolated from rat duodenum and named mobilferrin. Water-soluble homogenates were prepared from duodena of patients undergoing surgery for pancreatic carcinoma. An iron-binding protein with an approximate molecular mass of 56 Kd was purified to homogeneity using 60% ammonium sulfate and serial chromatographic steps. The protein was biochemically and immunologically distinct from transferrin and ferritin, and competitively bound to zinc, cobalt, and lead. Each molecule bound one molecule of iron with a kd of 8.9 x 10(-5). Human isolates reacted in an enzyme-linked immunosorbent assay with a polyclonal antibody raised in rabbits against a similar duodenal protein isolated from rat duodenum. It is postulated that mobilferrin plays a significant role in the absorption of iron and other metals and may explain partially the competition between certain metals for absorption in the small intestine.
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PMID:Newly identified iron-binding protein in human duodenal mucosa. 172 12

In attempting to determine the pathway of ferritin from Kupffer cells to liver parenchymal cells, anionic iron colloid particles of a ferric hydroxide-potassium polyvinyl sulfate complex (Fe-PVS) were injected intravenously into blood-depleted anemic rats. After iron loading, the process of ferritin formation and the daily change in the latter's distribution in the liver were studied by ultrastructural-immunocytochemical techniques. Three days after Fe-PVS injection, a mass of reaction products of ferritin was found in Kupffer cells, though not in the sinusoidal endothelial or parenchymal cells. Four days post-Fe-PVS injection, however, reaction products in Kupffer cells disappeared, while appearing in parenchymal cells. Observations at 3.5 days after the injection revealed heavy deposition of reaction products in the sinusoid and Disse's spaces as well. Electron microscopic observation of tissue sections treated with bismuth subnitrate taken at this stage revealed diffuse dispersion of ferritin particles in the cytoplasmic matrix of parenchymal cells as well as in the sinusoid and Disse's spaces. Ferritin particles were not found in the coated pits and vesicles of the Kupffer cells and parenchymal cells. Four days after injection, ferritin particles were found in clusters in the cytoplasm of the parenchymal cells and also in their lysosomal bodies. The results indicate that ferritin synthesized in Kupffer cells is released into sinusoidal and Disse's spaces and then accumulated in parenchymal cells.
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PMID:Transport of ferritin from Kupffer cells to liver parenchymal cells. Morphological and immunocytochemical observations. 174 51

Metabolic responses during a standardized, progressive, maximal work capacity test on a cycle ergometer were studied in 11 women, mean age 28 (SEM 2) years, at admission to the study, after their body iron stores were depleted by diet, phlebotomy and menstruation for about 80 days and after iron repletion by diet for about 100 days, including daily iron supplementation (0.9 mmol iron as ferrous sulfate) for the last 14 days of repletion. Iron depletion was characterized by a decline (P less than 0.05) in hemoglobin, ferritin and body iron balance. Iron repletion, including supplementation, increased (P less than 0.05) hemoglobin, ferritin and iron balance. No changes were observed in cardiovascular and ventilatory responses or peak oxygen uptake. Iron depletion was associated with a reduced (P less than 0.05) rate of oxygen utilization, total oxygen uptake and aerobic energy expenditure, and elevated (P less than 0.05) peak respiratory exchange ratio and post-exercise concentration of lactate. Reduction of body iron stores without overt anemia affects exercise metabolism by reducing total aerobic energy production and increasing glycolytic metabolism.
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PMID:Altered metabolic response of iron-deficient women during graded, maximal exercise. 174 5

Iron absorption by intestinal epithelial cells, passage onto plasmatic apotransferrin, and regulation of the process remain largely misunderstood. To investigate this problem, we have set up an in vitro model, consisting in CaCo2 cells (a human colon adenocarcinoma line, which upon cultivation displays numerous differentiation criteria of small intestine epithelial cells). Cells are cultivated in a serum-free medium, containing 1 microgram/ml insulin, 1 ng/ml epidermal growth factor, 10 micrograms/ml albumin-linoleic acid, 100 nM hydrocortisone, and 2 nM T3 on new, transparent, Cyclopore polyethyleneterephthalate microporous membranes coated with type I collagen. Cells rapidly adhere, grow, and form confluent monolayers; after 15 days, scanning electron microscopy reveals numerous uniform microvilli. Domes, which develop on nonporous substrata, are absent on high porosity membranes. Culture medium from upper and lower compartments of microplate inserts and cell lysates were immunoprecipitated after labeling with [3H]glucosamine and leucine; analysis was done by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), followed by autoradiography. [3H]transferrin is found mainly in the lower compartment and in cells; [3H]apolipoprotein B is released in both compartments, and fibronectin almost entirely recovered in the lower compartment; [3H]transferrin receptors and ferritin are only present in cell lysates. Binding experiments also show that transferrin receptors are accessible from the lower compartment. These results suggest that CaCo2 cells, cultivated in synthetic medium on membranes of appropriate porosity, could provide an in vitro model of the intestinal barrier, with the upper compartment of the culture insert corresponding to the apical pole facing the intestinal lumen and the lower one to the basal pole in contact with blood.
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PMID:Iron absorption by intestinal epithelial cells: 1. CaCo2 cells cultivated in serum-free medium, on polyethyleneterephthalate microporous membranes, as an in vitro model. 183 Mar 3


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