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Query: UNIPROT:P02794 (ferritin)
 17,525 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Chicken erythrocytes were fused either by Sendai virus or by the combination of Ca2+ and ionophore A23187. Intramembrane particles and external anionic sites of cells undergoing fusion were found to acquire the ability to undergo a process of cold-induced clustering (thermotropic separation). Cationized ferritin (200 microgram/ml 5% (v/v) cell suspension) inhibited both the fusion process and the thermotropic separation of intramembrane particles and external anionic sites. The correlation between the mobility of membrane proteins and the fusion process is discussed. It is suggest that an increase in the lateral mobility of membrane proteins is a prerequisite for initiation of membrane fusion.
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PMID:Inhibition of membrane fusion by suppression of lateral movement of membrane proteins. 21 87

Respiratory infection with Mycoplasma pneumoniae evokes immunoglobulin M autoantibody which agglutinates human erythrocytes at 4 degrees C (cold agglutinin) and is specific for I antigen. Cross-reactions between surface antigens of M. pneumoniae and human erythrocytes, previously examined by serological analysis, were examined by transmission and scanning electron microscopy. Ferritin-labeled human antimycoplasmal and rabbit antisera to erythrocyte membrane components reacted with antigens on the surface of both M. pneumoniae and erythrocytes. Adsorption of human erythrocytes to M. pneumoniae was blocked by the same antisera without ferritin label. It is proposed that the cross-reactive specificity lies in peripheral areas of the mycoplasmal cell, probably in a surface carbohydrate which has antigenic identity with erythrocyte glycoprotein.
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PMID:Immune electron microscopy of cross-reactions between Mycoplasma pneumoniae and human erythrocytes. 45 71

Syncytiotrophoblast microvillous plasma membrane (StMPM) preparations were obtained from human full-term placentae by previously published methods of cold saline extraction and phase centrifugation. Purity of these preparations was assessed by electron microscopy, enzyme analysis and hydroxyproline content. IgG, albumin, alkaline phosphatase, transferrin, ferritin and alpha 2-macroglobulin were consistently detected in the aqueous soluble fraction from sodium deoxycholate-solubilised StMPM preparations by antigenic or electrophoretic analysis, beta 2-Microglobulin was not detected in these preparations. Up to 21 discrete protein bands could be demonstrated by SDS--PAGE, and their molecular weights determined. Many of these components need to be further identified, including a glycoprotein of molecular weight 36 500 which was particularly prominent. The soluble fraction from StMPM preparations gave a single strong precipitin reaction in immunodiffusion against wheat germ agglutinin, but not against other lectins studied.
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PMID:Characterisation of the soluble fraction of human syncytiotrophoblast microvillous plasma membrane-associated proteins. 55 Nov 70

Two forms of cellulase, buffer soluble (BS) and buffer insoluble (BI), are induced as a result of auxin treatment of dark-grown pea epicotyls. These two cellulases have been purified to homogeneity. Antibodies raised against the purified cellulases were conjugated with ferritin and were used to localize the two cellulases. Tissue sections were fixed in cold paraformaldehyde-glutaraldehyde and incubated for 1 h in the ferritin conjugates. The sections were washed with continuous shaking for 18 h and subsequently postfixed in osmium tetroxide. Tissue incubated in unconjugated ferritin was used as a control. A major part of BI cellulase is localized at the inner surface of the cell wall in close association with microfibrils. BS cellulase is localized mainly within the distended endoplasmic reticulum. Gogli complex and plasma membrane appear to be completely devoid of any cellulase activity. These observations are consistent with cytochemical localization and biochemical data on the distribution of these two cellulases among various cell and membrane fractions.
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PMID:Subcellular localization of cellulases in auxin-treated pea. 76 48

The incorporation of ferric iron labelled with 59Fe into rat liver ferritin has been studied in whole animals, into liver homogenate and into purified protein. Uptake of Fe3+ into purified rat liver ferritin followed a pattern similar to that with horse spleen ferritin given Fe2+ and an oxidant. The distributions of iron incorporated as a function of molecular iron content obtained in vivo resembled the in vitro patterns for iron contents above 500 Fe atoms/molecule and times after injection of up to 12 h. At larger intervals a maximum label moved to molecules of highest iron content as the molecules accumulated more iron. The apparently reduced uptake of injected 59Fe into molecules of low iron content might be due either to the chase of cold iron through an existing iron pool or the presence of functionally different ferritins at more than one anatomic site within the cell.
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PMID:The uptake of ferric iron by rat liver ferritin in vivo and in vitro. 100 22

Physiological responses at 16 degrees C were studied in 11 women, age 28 +/- 2(mean +/- S.E.) years and 26 +/- 2% fat, after their body iron stores were depleted by diet (5.0 mg iron x 2,000 kcal-1 x d-1), phlebotomy and menstruation for about 80 d and were repleted by diet (13.7 mg iron x 2,000 kcal-1 x d-1) for about 100 d, including daily iron supplementation (50 mg of iron as ferrous sulfate) for the last 14 d of repletion. Iron depletion was characterized by a decline (p less than 0.05) in hemoglobin (12.0 +/- 0.2 g x dl-1), ferritin (5.5 +/- 0.5 ng x ml-1) and body iron balance (-9.1 +/- 2.6 mg x 6 d-1). Iron repletion, including supplementation, increased (p less than 0.05) hemoglobin (12.6 +/- 0.1 g x dl-1), ferritin (9.5 +/- 0.4 ng x ml-1) and iron balance (+67 +/- 6.7 mg x 6 d-1). Iron depletion reduced (p less than 0.05) metabolic heat production (49.6 +/- 1.1 vs 53.6 +/- 1.2 W x m-2) during acute cold exposure. The rates of cooling of the core and periphery were greater (p less than 0.05) during iron depletion than repletion. A shift in the lower core temperature threshold for shivering was paralleled by an earlier onset of shivering (p less than 0.05) in iron depletion indicating an adaptation in cold tolerance in an attempt to maintain core temperature. Iron depletion was associated with blunted post-exposure increases in plasma thyroid hormone concentrations and greater (p less than 0.05) increases in plasma norepinephrine concentrations as compared to iron repletion. In a subsample of the women, no significant effect of calcium or ascorbic acid supplementation was found on responses to cold exposure.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Thermogenesis and thermoregulatory function of iron-deficient women without anemia. 224 32

Polycationic derivatives of ferritin containing primary amino groups (CFah) or tertiary amino groups (CFdmp) were potent platelet agonists inducing shape change, aggregation and secretion, but also agglutination in the presence of EDTA. Pretreatment of platelets with neuraminidase, PGE1, indomethacin, or creatine kinase/creatine phosphate inhibited CF-induced activation. In contrast, neuraminidase and PGE1 increased the agglutination by CF, indicating an inverse relationship between activation and CF-induced agglutination. At pH 7.4, the cationic charges of CFdmp exceeded those of CFah by a factor of 1.5 and the platelets bound approximately 1.5 times more CFah than CFdmp, suggesting the same number of anionic surface sites for both CF preparations. The capacity of the platelets to bind CF was diminished by 55% at 0 degree C or by 62% after aldehyde fixation and by 13% with PGE1. This suggests that the binding capacity depends on the mobility of the binding sites in the plane of the membrane but is only slightly increased by platelet activation. Binding to fixed or cold platelets approached equilibrium within a few seconds whereas saturation required several minutes at 37 degrees C. Neuraminidase preferentially reduced the slow binding and much less the rapid binding. Since activation by CF developed during seconds, suppressible by a brief treatment with neuraminidase 25 mU/ml, a small portion of neuraminidase-sensitive sites appears to be necessary for CF-induced platelet activation. Full activation and agglutination occurred at CF concentrations far below saturating concentrations. The results show that neither CF-induced activation nor agglutination depend on a simple neutralization of the negative surface charge.
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PMID:Cationized ferritin as a platelet-stimulating surface probe. Binding to platelets and effects on platelet function. 308 60

Three purported means by which large solutes may penetrate the blood-brain barrier are: permeabilized tight junctions; vesicular transport; or channel formation across cerebral blood vessels. The role of vesicular transport has been questioned, in part, because many cytoplasmic vesicles are induced by aldehyde fixation. Cryofixation reduces this artefact and was used to see structural changes in frog cerebral endothelium made permeable to plasma solutes after perivascular exposure to hyperosmotic (3 M) urea, or injury with a cold probe (-50 degrees C). Some control and experimental frogs were made hypothermic so as to inhibit endocytosis and autolytic changes. The brains of some untreated controls were immerse-fixed in aldehydes. Other controls and all other brains of normothermic or hypothermic animals were rapidly frozen, then substituted with acetone-fixative. The interendothelial tight junctions separate partially or completely, after hyperosmotic exposure, in one third of the junctions. Blood-borne ferritin and Evans blue pass through some of the patent junctions. Junctional opening is caused by cell shrinkage, because the perimeter/area ratio of individual endothelial cells in the hyperosmotic group is significantly greater than in the control, due to a decreased area. Large 0.08-0.32-micron-wide invaginations or pits of the endothelial cell membrane characterize both cryofixed and aldehyde-fixed vessels. The pits often appear as isolated vesicles in the cytoplasm, but serial sections reveal that many communicate with either the capillary lumen or subendothelial space. No series of pits opened onto both lumen and space to form a transendothelial channel. The number of vesicles in aldehyde-fixed specimens is about 4 times greater (P less than 0.01) and in the cold injured, cryofixed brain capillary, about two times greater (P less than 0.01), than in the cryofixed control. Hyperosmotic exposure does not increase the number of pits. The permeabilization of anuran cerebral endothelium by hyperosmotic treatment or cold injury is thus by means of an intercellular rather than a transcellular route.
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PMID:Cerebral vessels cryofixed after hyperosmosis or cold injury in normothermic and hypothermic frogs. 325 81

1. We present the results of a study of the prevalence of anemia and its causes in the population of Ecuador. The following parameters were used: blood cytology, reticulocyte count, serum iron, iron binding capacity, ferritin, folic acid and vitamin B 12 concentration. 2. The study was carried out on 4 groups: 426 individuals of both sexes and all ages from the rural population of the lowlands, with a warm and humid climate; 226 individuals from the highlands, with a cold and dry climate; 1000 individuals of the urban working group from the lowlands; and 1000 individuals of the urban working group from the highlands. All subjects were chosen randomly. 3. The prevalence of anemia was 31.4% in the rural group from the lowlands, 27.9% in the rural group from the highlands, 5.5% in the urban group from the lowlands, and 2.7% in the urban group from the highlands, with an overall estimated prevalence of 20.6% for the population of Ecuador as a whole. Iron deficiency was the most frequent cause of anemia (91.3%; 18.7% of the total population), followed by bone marrow failure (6%; 1.2% of the total population), hemolysis (2.2%; 0.5% of the total population), and finally megaloblastic anemia (0.5%; 0.1% of the total population). 4. Since iron deficiency with and without anemia is very frequent, we believe it is justified to establish mechanisms for food iron enrichment for liable groups such as children and pregnant women from marginal areas.
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PMID:Prevalence of different types of anemia in Ecuador. 326 72

A cross-sectional epidemiological study was carried out among 141 male subjects exposed to inorganic manganese (Mn) in a Mn oxide and salt producing plant (mean age 34.3 years; duration of exposure, mean 7.1 years, range 1-19 years). The results were compared with those of a matched control group of 104 subjects. The intensity of Mn exposure was moderate as reflected by the airborne Mn levels and the concentrations of Mn in blood (Mn-B) and in urine (Mn-U). A significantly higher prevalence of cough in cold season, dyspnea during exercise, and recent episodes of acute bronchitis was found in the Mn group. Lung ventilatory parameters (forced vital capacity, FVC; forced expiratory volume in one second, FEV1; peak expiratory flow rate, PEFR) were only mildly altered in the Mn group (smokers) and the intensity and the prevalence of these changes were not related to Mn-B, Mn-U, or duration of exposure. There was no synergistic effect between Mn exposure and smoking on the spirometric parameters. Except for a few nonspecific symptoms (fatigue, tinnitus, trembling of fingers, increased irritability), the prevalence of the other subjective complaints did not differ significantly between the control and Mn groups. Psychomotor tests were more sensitive than the standardized neurological examination for the early detection of adverse effects of Mn on the central nervous system (CNS). Significant alterations were found in simple reaction time (visual), audioverbal short-term memory capacity, and hand tremor (eye-hand coordination, hand steadiness). A slight increase in the number of circulating neutrophils and in the values of several serum parameters (ie, calcium, ceruloplasmin, copper, and ferritin) was also found in the Mn group. There were no clear-cut dose-response relationships between Mn-U or duration of Mn exposure and the prevalence of abnormal CNS or biological findings. The prevalences of disturbances in hand tremor and that of increased levels of serum calcium were related to Mn-B. The response to the eye-hand coordination test suggests the existence of a Mn-B threshold at about 1 microgram Mn/100 ml of whole blood. This study demonstrates that a time-weighted average exposure to airborne Mn dust (total dust) of about 1 mg/m3 for less than 20 years may present preclinical signs of intoxication.
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PMID:Epidemiological survey among workers exposed to manganese: effects on lung, central nervous system, and some biological indices. 357 89


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