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

Mycobacterium bovis var. BCG was grown under iron-deficient conditions in the presence and absence of 1% Tween 80. Mycobactin, the iron iron ionophore of mycobacteria, was found solely within the bacteria grown in the absence of Tween, but low concentrations (0.75 mug/ml) of it appeared in the medium in the presence of the surfactant. Both types of medium contain agents, named exochelins, which could solubilize iron. 55Fe added to spent culture media was recovered only chelated to these compounds. Two exochelins were detected, isolated, and purified. Neither were precursors or breakdown products of mycobactin. In the desferri-form, exochelin MB-2, the major component, reversed the inhibitory effect of serum on the growth of BCG, and in their ferri-forms exochelins MB-1, MB-2, and MS (from Mycobacterium smegmatis) stimulated the growth of their producing organism in the presence of serum. Exochelin MB-2 could physically remove iron from ferritin, and BCG used ferritin as a source of iron during growth even when ferritin was separated from the bacteria by a dialysis membrane. As solutions of the exochelins were freely dialyzable, whereas solutions of mycobactin, even in Tween, were not, only exochelin could have been active in this experiment. The exochelins are proposed as the functional extracellular iron-binding agents of BCG and other mycobacteria, the role of mycobactin being confined to that of a cell wall iron transporter.
Infect Immun 1975 Dec
PMID:Extracellular iron acquisition by mycobacteria: role of the exochelins and evidence against the participation of mycobactin. 110 22

Mouse kidneys were perfused with Krebs-Ringer bicarbonate buffer (KRB) containing native, anionic horse spleen ferritin or various cationized derivatives, and the glomerular localization of the probe molecules determined by electron microscopy. Ferritins cationic with respect to the medium (KRB, pH 7.45) accumulated in the subendothelial layers of the glomerular basement membrane (GBM) in amounts far exceeding those observed with anionic ferritins, the degree being greater for the more cationized derivatives. Strongly cationized ferritins, in addition permeated the full thickness of the GBM in considerable amounts, but appeared to be retarded from entry into the urinary spaces at the level of the filtration slits. Very strongly cationized derivatives adhered to glomerular endothelium and GBM and formed aggregates in the outer layers of the latter. The results suggest that intrinsic negative charges are present in the GBM and endothelium, and that the barrier function of the glomerular capillary wall may be ascribed in part to its electrophysical properties.
J Cell Biol 1975 Dec
PMID:Role of molecular charge in glomerular permeability. Tracer studies with cationized ferritins. 120 17

The measurement of liver ferritin is usually performed after homogenization of liver, heating the homogenate and centrifugation. Because ferritin is stable to 80 degrees this protein and its iron are recovered in the supernatant. We found that this procedure resulted in losses of ferritin so we developed a method to measure ferritin protein in the unheated homogenate. Total liver ferritin iron could be calculated with use of the ferritin protein and ferritin iron values as measured in the supernatant after heating the liver homogenate.
Clin Chim Acta 1975 Dec 15
PMID:On the quantitative determination of liver ferritin in the rat. 120 23

After indian ink or ferritin are introduced into the cerebral hemispheres or subdural space these substances can be found in the deep cervical lymph nodes. The transport of these substances can be enhanced and accelerated by the treatment of deep cervical lymph nodes by ultrasound. Treatment of the paravertebral region with ultrasound after the introduction of ferritin or indian ink subdurally is followed by the appearance of these substances in the suprarenal gland, the testis, epididymis and the prostate gland where they are conveyed by the lymphatic pathways. Thirty minutes after the injection of ferritin into an afferent lymphatic channel of a deep cervical lymphatic node pretreated with ultrasound, ferritin can be found in the pia and arachnoid membranes of the cerebral hemispheres. Ultrasound treatment of the cervical lymph nodes not only seems to enhance the drainage of this substance from the brain but if the dose of ultrasound is high the direction of the lymphatic flow may be reversed.
Acta Neuropathol 1975 Dec 19
PMID:[Experimental study on the lymphatic and cerebrocervical drainage and changes therein caused by ultrasound (author's transl)]. 121 Nov 11

The labelling of negative charges on the cell surface of the developing promastigote forms in Leishmania donovani, L. tropica and L. braziliensis was determined using cationized ferritin and electron microscopy. Ferritin deposits were seen exclusively on the pellicle, since they cannot penetrate the cell membrane. The ferritin particles were distributed in regular rows covering the whole cell surface. The mean diameter of the particles was 8.76 nm and at a magnification of 104.000 an average of 9.8 particles was detected on 1 cm cell surface. Only in the membrane of the proximal part of the reservoir labelling was frequently absent. The possible explanations for this observation were discussed. There was no difference in the pattern size of the ferritin particles or in their number per cm cell surface among the various strains of L. donovani on the one hand or between L. donovani, L. tropica and L. braziliensis on the other.
Tropenmed Parasitol 1975 Dec
PMID:[Comparative electron microscope studies on the labelling Leishmania donovani, Leishmania tropica and Leishmania braziliensis with ferritin (author's transl)]. 121 27

Foetal lambs were immunized orally 6-15 days before birth by introducing horse spleen ferritin into the amniotic fluid. Immunized and non-immunized lambs were killed at birth, usually before they had suckled, blood and intestinal contents were collected and single cell suspensions were prepared from spleen, mesenteric lymph nodes and jejunum. Specific antibody was detected in serum and intestinal contents of all immunized lambs which had not suckled. Specific antibody was usually not detected in samples from non-immunized lambs. In immunized lambs antibody activity in serum was associated with IgM and in intestinal contents with IgA and IgM. In agreement with these findings, the levels of IgM and IgA in serum and intestinal contents of immunized lambs were relatively high. Generally, immunoglobulins were not detected in samples from non-immunized lambs. Relatively high proportions of cells secreting specific antibody were present in the tissues of immunized but not non-immunized lambs. In the spleen most of the cells were secreting IgM antibody, in mesenteris lymph nodes IgM cells predominated and small numbers of IgA cells were detected, and in the jejunum approximately equal numbers of IgA and IgM cells were secreting specific antibody.
Immunology 1975 Dec
PMID:Local and systemic immune responses following oral immunization of foetal lambs. 123 67

The translation of ferritin mRNA and degradation of transferrin receptor mRNA are regulated by the interaction of an RNA-binding protein, the iron-responsive element binding protein (IRE-BP), with RNA stem-loop structures known as iron-responsive elements (IREs) contained within these transcripts. IRE-BP produced in iron-replete cells has aconitase (EC 4.2.1.3) activity. The protein shows extensive sequence homology with mitochondrial aconitase, and sequences of peptides prepared from cytosolic aconitase are identical with peptides of IRE-BP. As an active aconitase, IRE-BP is expected to have an Fe-S cluster, in analogy to other aconitases. This Fe-S cluster has been implicated as the region of the protein that senses intracellular iron levels and accordingly modifies the ability of the IRE-BP to interact with IREs. Expression of the IRE-BP in cultured cells has revealed that the IRE-BP functions either as an active aconitase, when the cells are iron-replete, or as an active RNA-binding protein, when the cells are iron-depleted. We compare properties of purified authentic cytosolic aconitase from beef liver with those of IRE-BP from tissue culture cells and establish that characteristics of the physiologically relevant form of the protein from iron-depleted cells resemble those of cytosolic aconitase apoprotein. We demonstrate that loss of the labile fourth iron atom of the Fe-S cluster results in loss of aconitase activity, but that more extensive cluster alteration is required before the IRE-BP acquires the capacity to bind RNA with the affinity seen in vivo. These results are consistent with a model in which the cubane Fe-S cluster is disassembled when intracellular iron is depleted.
Proc Natl Acad Sci U S A 1992 Dec 15
PMID:Cellular regulation of the iron-responsive element binding protein: disassembly of the cubane iron-sulfur cluster results in high-affinity RNA binding. 128 44

Nonheme iron proteins can be visualized as blue bands in native polyacrylamide gels using a staining method that is both simple and rapid. The reaction of potassium ferricyanide with protein-bound iron atoms to form royal blue complexes occurs almost instantaneously and is sensitive enough to detect 1 microgram of analytical-grade ferritin and 2 micrograms of purified ferredoxin from cyanobacteria. No special treatment of reagents or apparatus was necessary. On comparison, this stain was found to be more specific than the Ferene S stain, not detecting bovine serum albumin even when present as a hundredfold excess over ferritin. The method was found to be effective for isoelectric focusing gels as well.
Anal Biochem 1992 Dec
PMID:A specific stain for the detection of nonheme iron proteins in polyacrylamide gels. 128 87

Rats were made hypo and 'hyperthyroid' with propylthiouracil (PTU) and L-Thyroxine (L-T) respectively. The hypo and hyperthyroid status in these rats were confirmed by serum level of T4 and T3. Liver iron was significantly increased in both the hypo and hyperthyroid animals. However, liver ferritin synthesis rate was reduced by 36% in hypothyroid rats, and elevated by 38% in hyperthyroid ones. A similar trend was seen in liver ferritin concentration. Further, serum transaminases were elevated only in animals of the hyperthyroid group. It appears from the present data that ferritin metabolism is influenced by thyroid hormone as well as by iron. Thus, the raised serum ferritin in hyperthyroid patients may be partially attributed to increased ferritin synthesis in the liver and its possible leakage into circulation.
Thyroidology 1992 Dec
PMID:Relation between thyroid status and ferritin metabolism in rats. 128 38

To investigate the etiology of the age-related decrease in hemoglobin (Hb) concentration, we measured serum erythropoietin (EPO), serum iron, total iron binding capacity, and serum ferritin levels in 247 elderly subjects aged 60-99 years. EPO levels were determined by radioimmunoassay. An age-related increase in the serum EPO concentration (r = 0.220; P < 0.01) and a significant inverse relationship between EPO and Hb concentrations were found in normal elderly subjects without anemia (r = -0.302; P < 0.001), but not in 111 younger controls. Serum EPO levels were slightly higher in elderly subjects with pre-anemic iron deficiency than in the normal elderly subjects (P < 0.05). These results suggest that the EPO secretion is accelerated in the elderly even though the Hb remains above 12.0 g/dl, probably as a compensatory mechanism for peripheral tissue hypoxia. An inverse relationship between the EPO and Hb concentrations was found in the elderly subjects with iron deficiency anemia, but not in those with unexplained senile anemia. The changes of EPO levels were also assessed in 20 elderly subjects who had developed anemia when reviewed after 12 months. Serum EPO levels increased in relation to the decrease in Hb concentration in those with iron deficiency anemia, but not in those with unexplained senile anemia. Reduced EPO secretion thus seems to play a role in the progression of unexplained senile anemia, and recombinant human EPO may possibly be effective for treating this type of anemia by mobilizing excess iron.
Am J Hematol 1992 Dec
PMID:Reduced erythropoietin secretion in senile anemia. 128 87


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