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

Bretscher (1983) has shown that on uniformly spread giant HeLa cells, the receptors for low density lipoprotein (LDL) and transferrin are concentrated toward the periphery of the cells. To explain these nonuniform distributions, he proposed that on giant HeLa cells, recycling receptors return to the cell surface at the cell's leading edge. Since the distribution of coated pits on these cells is uniform, Bretscher and Thomson (1983) proposed that there is a bulk membrane flow toward the cell centers. Here we present a mathematical model that allows us to predict the distribution of cell surface proteins on a thin circular cell, when exocytosis occurs at the cell periphery and endocytosis occurs uniformly over the cell surface. We show that on such a cell, a bulk membrane flow will be generated, whose average velocity is zero at the cell center and increases linearly with the distance from the cell center. Our model predicts that proteins that aggregate in coated pits will have concentrations that are maximal at the cell periphery. We fit our theory to the data of Bretscher and Thomson (1983) on the distribution of ferritin receptors for the following cases: the receptors move by diffusion alone; they move by bulk membrane flow alone; they move by a combination of diffusion and bulk membrane flow. From our fits we show that tau m greater than 3.5 tau p, where tau m and tau p are the lifetimes of the membrane and the ferritin receptor on the cell surface, and that tau pD less than 6.9 X 10(-7) cm2, where D is the ferritin receptor diffusion coefficient. Surprisingly, we obtain the best fits to the data when we neglect membrane flow. Our model predicts that for proteins that are excluded from coated pits, the protein concentration will be Gaussian, being maximal at the cell center and decreasing with the distance from the cell center. If on giant HeLa cells a protein with such a distribution could be found, it would strongly support Bretcher's proposal that there is an inward membrane flow.
 ...
PMID:The distribution of cell surface proteins on spreading cells. Comparison of theory with experiment. 283 Sep 22

Elemental mapping consists in searching the distribution of a given chemical species over an extended specimen area, with relation to topographical or structural features. It can be done with EELS core signals from a combination of several energy filtered images. One major problem encountered in the processing of such sequences of images lies in the extrapolation errors due to a difficult estimate of the background below the characteristic signal. The chosen method must be sufficiently reliable to avoid the risk of both "false positive" and "false negative" values: the first category may stem from spurious signals or from a non-satisfactory fit of the background. The second category is mainly due to a limited sensitivity. The EELS signal is often much weaker than the background intensity; an extrapolation error can therefore transform a negative value into a positive one, or vice versa. The purpose of the present contribution is to check the validity of the processing at different levels: i) different mathematical models of background; ii) different types of fitting procedures (one-parameter and two-parameters fits); iii) different fitting methods and several associated manipulations, such as a quasi local estimation of the involved fitting parameters. The statistical validity of those techniques is discussed through several tests on real images obtained from different specimens (Co/CeO2 catalysts, ferritin molecules, U and Tb staining clusters). Progress is made on the way of quantitative elemental mapping at a given confidence level, and towards the identification of single atoms.
 ...
PMID:Developments in processing image sequences for elemental mapping. 324 73

One hundred and four infants with neurological symptoms or suspected infection during the neonatal period were consecutively investigated with respect to ferritin and albumin concentrations in the cerebrospinal fluid (CSF). In some cases serial determinations of CSF ferritin were performed during the period in the neonatal unit. CSF ferritin was significantly higher in infants that recovered very soon from a transient neonatal disorder (TND) than in apparently healthy adults. No difference in CSF ferritin was found between full-term infants with TND and pre-term infants with TND or asphyxiated infants. Three out of five infants with septicaemia or meninigitis showed a marked increase in CSF ferritin during the observation period, and the same finding was made in three infants with intracranial bleeding, in whom CSF ferritin values 100 times the upper reference limit for infants with TND were recorded. In two infants with neonatal convulsions secondary to asphyxia moderate CSF elevations were observed. No correlation was found between ferritin and albumin in CSF, suggesting that other mechanisms than passive penetration from blood into CSF must have been responsible for the raised levels of CSF ferritin. More likely the observed ferritin increments reflect ferritin release from macrophages undergoing phagocytosis either induced by cerebral bleeding or due to infectious agents.
 ...
PMID:Cerebrospinal fluid ferritin in newborn infants. Elevated levels in cerebral infection or bleeding. 713 23

Recombinant human erythropoietin was given to eight children and adolescents with stable chronic renal failure in the predialysis state. The hormone was administered subcutaneously, twice weekly for 12 weeks, at a starting dose of 50 U/kg per week. The dosage was adapted every 4th week. Target haemoglobin was 10.5-11.5 g/dl, and the target haematocrit 32%-35%. Baseline haemoglobin levels of 8.20 +/- 0.93 g/dl increased to 9.17 +/- 1.10, 10.38 +/- 1.18 and 11.19 +/- 0.84 g/dl (mean +/- SD) after 4, 8 and 12 weeks respectively. Serum ferritin levels decreased progressively despite iron supplementation. No side-effects were observed: creatinine clearances remained stable, blood pressure did not increase and none of the patients displayed either convulsions or thrombotic features. The study shows that subcutaneous recombinant human erythropoietin is both effective and safe in anaemic children and adolescents with chronic renal insufficiency.
 ...
PMID:Subcutaneous recombinant erythropoietin in preterminal renal insufficiency. 815 20

We report marked intracerebral calcification in eight thalassemic patients with hypoparathyroidism, followed regularly at the Haematology Research Center, Department of Pediatrics, Shiraz, Iran. Their mean age was 16.8 years (range 12-21 years). Six of the eight patients with thalassemia were females. The daily dose of calcitriol was between 0.01 and 0.1 microg/kg b. wt. Calcium-phosphate metabolic control was good or satisfactory in all patients. Three patients had at least one episode of generalized convulsions caused by hypocalcemia, before and during treatment. One patient complained of chronic headache and another patient had a low intelligence quotient. All were on treatment with calcitriol and oral calcium supplementation. The mean serum ferritin concentration was 3225 microg/l (range 2000-6000 microg/l). Calcification was present in the cerebral hemispheres, thalamic nuclei, basal ganglia, the internal capsule, part of the caudate nuclei and the posterior fossa. There was no history of birth asphyxia, head trauma, infections or metabolic diseases in any of the patients. No relationship was observed between the degree of cerebral calcification and the severity of hypoparathyroidism at diagnosis. Our observations stress the importance of a periodic assessment of calcium metabolism, prompt treatment of the endocrinopathy and strict control of calcium metabolism.
 ...
PMID:Hypoparathyroidism with extensive intracerebral calcification in patients with beta-thalassemia major. 1294 1

The role of oxidative stress in the regulation of the copy number of mitochondrial DNA (mtDNA) in human leukocytes is unclear. In this study, we investigated the redox factors in plasma that may contribute to the alteration of mtDNA copy number in human leukocytes. A total of 156 healthy subjects of 25-80 years of age who exhibited no significant difference in the distribution of subpopulations of leukocytes in blood were recruited. Small-molecular-weight antioxidants and thiobarbituric acid reactive substances (TBARS) in plasma and 8-hydroxy-2'-deoxyguanosine (8-OHdG) and 4,977bp deletion of mtDNA in leukocytes were determined. The mtDNA copy number in leukocytes was determined by real-time PCR. The results showed that the copy number of mtDNA in leukocytes was changed with age in a biphasic manner that fits in a positively quadratic regression model (P = 0.001). Retinol (P = 0.005), non-protein thiols (P = 0.001) and ferritin (P = 0.004) in plasma and total glutathione in erythrocytes (P = 0.046) were the significant redox factors that correlated with the mtDNA copy number in leukocytes in a positive manner. By contrast, alpha-tocopherol levels in plasma (P = 0.001) and erythrocytes (P = 0.033) were negatively correlated with the mtDNA copy number in leukocytes. Three oxidative indices including the incidence of 4,977 bp deletion of mtDNA (P = 0.016) and 8-OHdG content in leukocytes (P = 0.003) and TBARS in plasma (P = 0.001) were all positively correlated with the copy number of mtDNA in leukocytes. Taken these findings together, we suggest that the copy number of mtDNA in leukocytes is affected by oxidative stress in blood circulation elicited by the alteration of plasma antioxidants/prooxidants and oxidative damage to DNA.
 ...
PMID:Oxidative stress-related alteration of the copy number of mitochondrial DNA in human leukocytes. 1475 55

The atomic force microscope, together with the colloid probe technique, has become a very useful instrument to measure interaction forces between two surfaces. Its potential has been exploited in this work to study the interaction between protein (apoferritin) layers adsorbed on silica surfaces and to analyze the effect of the medium conditions (pH, salt concentration, salt type) on such interactions. It has been observed that the interaction at low salt concentrations is dominated by electrical double layer (at large distances) and steric forces (at short distances), the latter being due to compression of the protein layers. The DLVO theory fits these experimental data quite well. However, a non-DLVO repulsive interaction, prior to contact of the protein layers, is observed at high salt concentration above the isoelectric point of the protein. This behavior could be explained if the presence of hydration forces in the system is assumed. The inclusion of a hydration term in the DLVO theory (extended DLVO theory) gives rise to a better agreement between the theoretical fits and the experimental results. These results seem to suggest that the hydration forces play a very important role in the stability of the proteins in the physiological media.
 ...
PMID:Existence of hydration forces in the interaction between apoferritin molecules adsorbed on silica surfaces. 1620 34

The Phlebobranch ascidian Perophora annectens surprisingly exhibited a biological Fe/V ratio of approximately 15:1 on multichannel X-ray fluorescence analysis of two independent collections of organisms. Iron K-edge X-ray absorption spectroscopy (XAS) indicated a single form of iron. The XAS K-edge of the first collection of blood cells was shifted approximately +1 eV relative to that of the second, indicating redox activity with average iron oxidation states of 2.67+ and 2.60+. The first-derivative iron XAS K-edge features at 7120.5, 7124, and 7128 eV resembled the XAS of magnetite but not of ferritin or of dissolved Fe(II) or Fe(III). Pseudo-Voigt fits to blood-cell iron K-edge XAS spectra yielded 12.4 integrated units of preedge intensity, indicating a noncentrosymmetric environment. The non-phase-corrected extended X-ray absorption fine structure (EXAFS) Fourier transform spectrum showed a first-shell O/N peak at 1.55 angstroms and an intense Fe-Fe feature at 2.65 angstroms. Fits to the EXAFS required a split first shell with two O at 1.93 angstroms and three O at 2.07 angstroms, consistent with terminal and bridging alkoxide ligands, respectively. More distant shells included three C at 2.87 angstroms, two Fe at 3.08 angstroms, three O at 3.29 angstroms, and one Fe at 3.8 angstroms. Structural models consistent with these findings include a [Fe4(OR)13](2-/3-) broken-edged Fe4O5 cuboid or a [Fe4(OR)14](3-/4-) "Jacob's ladder" with three edge-fused Fe2(OR)2 rhombs. Either of these models represents an entirely new structural motif for biological iron. Vanadium domination of blood-cell metals cannot be a defining trait of Phlebobranch tunicates so long as P. annectens is included among them.
 ...
PMID:A new structural motif for biological iron: iron K-edge XAS reveals a [Fe4-mu-(OR)5(OR)(9-10)] cluster in the ascidian Perophora annectens. 1667 50

We reported a girl with HHV-6 infection associated with both acute encephalopathy with biphasic seizures and late reduced diffusion, and hemophagocytic syndrome. She had a prolonged convulsion after a one-day history of febrile illness. Cerebrospinal fluid or brain CT showed no abnormalities on admission and her consciousness was recovered on the next day. However, a prolonged seizure and deterioration of consciousness appeared on the sixth day of illness. Diffusion-weighted images revealed marked reduction of water diffusion in the bilateral frontal areas. HHV-6 infection was virologically proven by polymerase chain reaction. She was treated with gamma-globulin, steroid pulse therapy, and brain hypothermia. In addition, decrease in white blood cells and platelet counts, and elevation of liver enzymes and ferritin were noted on the fourth day of illness. Hemophagocytic macrophages were revealed by bone marrow aspiration on the sixth day. Her hematological and blood chemistry abnormalities recovered gradually after steroid pulse therapy. An elevation of interleukin-6, -8, and -10, and tumor necrosis factor in the serum and that of interleukin-4, -6, and-8 in the cerebrospinal fluid were observed at the onset of a late seizure. These facts suggested that hypercytokinemia will be related to the pathogenesis of acute encephalopathy of our patient.
 ...
PMID:Acute encephalopathy with biphasic seizures and late reduced diffusion associated with hemophagocytic syndrome. 1955 82

We conducted this study to determine the role of iron deficiency as a risk factor for first febrile seizure in children. Fifty children between 6 months to 6 years with first febrile seizure (Cases) and 50 children with febrile illness but without convulsions (Controls) were enrolled from the pediatric ward of a tertiary care hospital. Iron deficiency was determined by estimation of hemoglobin, red blood cell indices and serum ferritin. The mean serum ferritin level (microg/L) was significantly low in Cases (31.9 +/- 31.0) as compared to Controls (53.9 +/- 56.5) with P = 0.003. Iron deficiency could be a potential risk factor for febrile seizure in children.
 ...
PMID:Iron deficiency as a risk factor for first febrile seizure. 1973 64


1 2 Next >>