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At least 19 recordsLinked to original sources

PubMed1994

cDNA cloning and deduced amino acid sequence of two ferritins: soma ferritin and yolk ferritin, from the snail Lymnaea stagnalis L.

Pulmonate freshwater snails contain two different ferritin types, soma ferritin and yolk ferritin. A cDNA library was constructed from midgut gland poly(A)-rich RNA of the snail Lymnaea stagnalis L. and recombinant clones encoding both ferritin types were obtained by immunoscreening. The longest cDNA inserts had a length of 859 bp (soma ferritin) and 1548 bp (yolk ferritin) and the specificity of these inserts was confirmed by immunoprecipitation of both ferritin types translated in vitro from hybrid-selected mRNAs. The 5' untranslated region (UTR) of the soma ferritin mRNA contains a 28-bp element which shows 64% sequence identity with the iron-responsive element (IRE) of vertebrate ferritin mRNAs. The soma ferritin mRNA is strongly translated in the wheat germ system but poorly translated in rabbit reticulocyte lysate. The yolk ferritin mRNA, which contains no IRE, is equally well translated in both in vitro translation systems. The deduced amino acid sequence of the soma ferritin subunit (174 amino acid residues, M(r) 20140) shows 50-70% sequence identity with subunits of vertebrate ferritins. After removal of an 18-amino-acid-residue signal sequence the deduced protein sequence of yolk ferritin contains 221 amino acids (M(r) 25438). Sequence identity of this chain with other eukaryotic ferritin chains is only 31-42%. Both snail ferritin sequences are more similar to the H-subunit type of vertebrate ferritins than to the L-type and both have the H-specific amino acid residues of the ferroxidase centre. The yolk ferritin sequence has a 42-amino-acid-residue insertion predicted to reside in the L loop of the subunit.

Amino Acid Sequence↗

PubMed1996

[Age-related changes in concentrations of ferritin, glyeosylated ferritin, and non-glycosylated ferritin].

We studied age-related changes in the concentrations in serum of ferritin, glycosylated ferritin, and non-glycosylated ferritin. The concentrations were determined in 95 healthy subjects: 39 men and 56 women, aged from 22 to 94 years. In the men, age correlated significantly with serum ferritin (r = 0.332, p < 0.05) and non-glycosylated serum ferritin (r = 0.628, p < 0.001) but not with glycosylated serum ferritin. In the women, age correlated significantly with serum ferritin (r = 0.456, p < 0.001), non-glycosylated serum ferritin (r = 0.439, p < 0.001), and glycosylated serum serum ferritin (r = 0.415, p < 0.01). The ratio of glycosylated serum ferritin to serum ferritin correlated negatively with age both in men and in women (men: r = -0.661, p < 0.001; women: r = -0.411, p < 0.01). Serum non-glycosylated ferritin levels were higher in older men. Both serum glycosylated ferritin and non-glycosylated ferritin levels were higher in older women, but this phenomenon was more pronounced with respect to the non-glycosylated form. These results suggest that hyperferritinemia in the elderly is mainly caused by an increase in the concentration of non-glycosylated ferritin, both in men and in women.

Adult↗

PubMed1983

Regulation of ferritin mRNA: a possible gene-sparing phenomenon. Induction of ferritin synthesis by iron in liver as well as red cells combines high translational efficiency with increased utilization of preformed ferritin mRNA.

Control of ferritin synthesis by iron at the level of transcription is potentially hazardous to DNA because of the iron-catalyzed degradation of DNA. The induction of ferritin synthesis in reticulocytes of embryos (bullfrog tadpoles) occurs by two types of translational control i.e. increased availability of stored ferritin mRNA, in response to iron, coupled with a high translational efficiency. Since erythroid cell nuclei have large amounts of heterochromatin and may be relatively inactive genetically, the translational control of ferritin by iron observed in red cells was studied in other tissue by isolating poly (A+) RNA from tadpole liver and analyzing protein synthesis in vitro. Liver ferritin mRNA directed the synthesis of 7.0% of the protein in a wheat germ system, compared to 1.2% in vivo, suggesting that tadpole liver contained a large amount of stored ferritin mRNA. At levels of poly (A+) RNA which were saturating for total protein synthesis, ferritin synthesis was still linearly dependent upon RNA concentration, indicating a high efficiency of translation of ferritin mRNA. The results are analogous to those previously observed in red cells and confirm the storage of ferritin mRNA deduced from studies of the polysomal and nonpolysomal distribution of the mRNA in rat liver. The results indicate that the increased availability for translation of stored ferritin mRNA, in response to iron, and the high translational efficiency of ferritin mRNA are a general characteristic of ferritin synthesis rather than a specific feature of red cell maturation. This novel form of regulation of ferritin gene expression can be attributed to a need to protect DNA from degradation by iron and oxygen. The normal barrier between DNA and iron is apparently breached by the iron-oxygen complex of the drug bleomycin, an antitumor agent thought to act in vivo by iron-catalyzed cleavage of DNA.

Animals↗

PubMed1994

Iron incorporation into ferritins: evidence for the transfer of monomeric Fe(III) between ferritin molecules and for the formation of an unusual mineral in the ferritin of Escherichia coli.

Iron that has been oxidized by H-chain ferritin can be transferred into other ferritin molecules before it is incorporated into mature ferrihydrite iron cores. Iron(III) dimers are formed at the ferroxidase centres of ferritin H chains at an early stage of Fe(II) oxidation. Mössbauer spectroscopic data now show that the iron is transferred as monomeric species arising from dimer dissociation and that it binds to the iron core of the acceptor ferritin. Human H-chain ferritin variants containing altered threefold channels can act as acceptors, as can the ferritin of Escherichia coli (Ec-FTN). A human H-chain ferritin variant with a substituted tyrosine (rHuHF-Y34F) can act as a donor of Fe(III). Since an Fe(III)-tyrosinate (first identified in bullfrog H-chain ferritin) is absent from variant rHuHF-Y34F, the Fe(III) transferred is not derived from this tyrosinate complex. Mössbauer parameters of the small iron cores formed within Ec-FTN are significantly different from those of mammalian ferritins. Analysis of the spectra suggests that they are derived from both ferrihydrite and non-ferrihydrite components. This provides further evidence that the ferritin protein shell can influence the structure of its iron core.

Escherichia coli↗

PubMed1981

Mobilization of iron from ferritin by isolated mitochondria. Effects of species compatibility between ferritin and mitochondria and iron content of ferritin.

Mitochondria mobilize iron from ferritin by a mechanism that depends on external FMN. With rat liver mitochondria, the rate of mobilization of iron is higher from rat liver ferritin than from horse spleen ferritin. With horse liver mitochondria, the rate of iron mobilization is higher from horse spleen ferritin than from rat liver ferritin. The results are explained by a higher affinity between mitochondria and ferritins of the same species. The mobilization of iron increases with the iron content of the ferritin and then levels off. A maximum is reached with ferritins containing about 1 200 iron atoms per molecule. The results represent further evidence that ferritin may function as a direct iron donor to the mitochondria.

Animals↗

PubMed1989

Transcriptional regulation of ferritin H and L subunits in adult erythroid and liver cells from the mouse. Unambiguous identification of mouse ferritin subunits and in vitro formation of the ferritin shells.

Ferritin H and L subunits present cell-specific features of structure, function, and transcriptional regulation. Mouse Friend erythroleukemia cells offer an interesting model to analyze the erythroid-specific expression of ferritin genes for comparison with the liver, an iron-storing tissue. cDNA clones for mouse ferritin H and L subunits have been isolated and sequenced. The two subunits have very similar calculated masses, 20.9 and 20.6 kDa for H and L, respectively. Electrophoretic analysis of the subunits encoded by the cDNA 1) allows unambiguous identification of mouse ferritin subunits; 2) clearly shows that mouse H and L chains can make heteropolymers in vitro; and 3) demonstrates that, at least in vitro, free subunits can coexist with subunits polymerized into complete shells. The mouse ferritin gene family displays a variable degree of complexity, ranging from three homologous sequences for the H genes to 10-14 homologous loci for the L genes. Transcription of ferritin genes exhibits tissue-specific difference. Nuclear transcriptional run-off experiments show that the L gene is more actively transcribed in the liver than in Friend erythroleukemia cells at different stages of maturation. The accumulation of the H subunit mRNA which results from dimethyl sulfoxide induction of Friend cells is the consequence of an increase in the transcription rate of the H gene. However, the H gene mRNA is transcribed at a similar rate in the liver and in induced Friend cells although 5-fold more mRNA accumulates in these cells. Therefore, there is a tissue-specific regulation of mouse ferritin expression at both the transcription and mRNA stability levels.

Animals↗

PubMed1999

Erythropoiesis: Short Report: Translation of Analysis Results between Serum Ferritin Assays, Ferritin RIA AmershamTM and Abbott AxSYMTM Ferritin.

The serum ferritin assays, Ferritin RIA Amersham(TM) and Abbott AxSYM(TM) Ferritin were compared in order to translate values from one assay to the other. Serum ferritin was analysed with both assays in 102 samples. Logarithmic transformation of the results was performed in order to stabilize the variance. The relationship between the untransformed values was most exactly expressed by a proportionality: AxSYM Ferritin = 0.873 * RIA Ferritin. Due to this proportionality, the numerical difference between the assays increases with the ferritin concentration, although the percentage difference between the assays remains constant.

Journal Article↗

PubMed1986

Differential localization of ferritin and ferritin immune complexes in the spleen: influence of the charge of ferritin.

Prior studies have demonstrated that following administration to animals most antigens (Ag) localize within the red pulp whereas immune complexes (IC) are found in the white pulp. Using ferritin and ferritin IC, we describe a striking different localization of the Ag alone compared with the same AG complexed with its antibody. In addition, cationization of native ferritin (pI 4.5) to cationized ferritin (pI 7) decreases significantly the splenic uptake of the Ag but has no effect on the uptake of the respective ferritin IC by the white pulp.

Animals↗

PubMed1985

Characterization of the binding of ferritin to the rat liver ferritin receptor.

The binding characteristics and specificity of the rat hepatic ferritin receptor were investigated using ferritins prepared from rat liver, heart, spleen, kidney and serum, human liver and serum, guinea pig liver and horse spleen as well as ferritins enriched with respect to either H- or L-type subunit composition, prepared by chromatofocusing of rat liver ferritin on Mono-P or by reverse-phase chromatography of ferritin subunits on ProRPC 5/10. No significant difference was apparent in the binding of any of the tissue ferritins, or of ferritins of predominantly acidic or basic subunit composition. However, serum ferritin bound with a lower affinity. The effect of carbohydrate on the ferritin-receptor binding was examined by glycosidase treatment of tissue and serum ferritins. Tissue ferritin binding was unaffected, while serum ferritin binding affinity was increased to that of the tissue ferritins. Inhibition of ferritin binding by lactoferrin was not due to common carbohydrate moieties as previously suggested but was due to direct binding of lactoferrin to ferritin. Therefore, carbohydrate residues do not appear to facilitate receptor-ferritin binding, and sialic acid residues present on serum ferritin may in fact interfere with binding. The results indicate that the hepatic ferritin receptor acts preferentially to remove tissue ferritins from the circulation. The lower binding affinity of serum ferritin for the ferritin receptor explains its slower in vivo clearance relative to tissue ferritins.

Animals↗

PubMed2000

Differential regulation of H- and L-ferritin messenger RNA subunits, ferritin protein and iron following focal cerebral ischemia-reperfusion.

Iron may catalyse the production of reactive oxygen species during post-ischemic reoxygenation and subsequently lead to brain damage. Ferritin, an iron sequestering and storage protein, can also be a source of iron after ischemic insult. However, its role in ischemia-reperfusion has not been carefully investigated. In the present study, we examined the temporal and spatial induction profiles of both H- and L-ferritin messenger RNA and protein in a well-defined focal cerebral ischemia model. Results of northern blot analysis showed a delayed and prolonged induction of both H- and L-ferritin messenger RNA in the ischemic cortex of rats subjected to 60min ischemic insult. A significant induction of both H- and L-ferritin messenger RNA was observed at 12h and remained elevated for up to 336h after the onset of reperfusion. At the peak level, quantitative analysis of the blot indicated a 2.5-fold and a six-fold increase in H- and L-ferritin messenger RNA, respectively, compared with the sham-operated controls. No apparent change in the levels of either messenger RNA was observed in the contralateral side. Results of in situ hybridization studies revealed constitutive expression of both H- and L-ferritin messenger RNA throughout the brain in sham-operated animals, in particular the hippocampus and the piriform cortex. Nevertheless, the signal intensity of H-ferritin messenger RNA was much higher than that of L-ferritin messenger RNA. Seventy-two hours after 60min ischemia, marked expression of H-ferritin messenger RNA was observed in the area surrounding the middle cerebral artery irrigated cortex, the medial part of the caudoputamen and in the subfield of the CA1 hippocampal region of the ipsilateral hemisphere. Similarly, a large induction of L-ferritin messenger RNA was also noted in several areas, including the middle cerebral artery irrigated cortex, the lateral part of the caudoputamen and the stratum pyramidale of the CA1 hippocampal region, which were totally different from areas where H-ferritin messenger RNA was found. At 336h after ischemia, increased expression of H-ferritin messenger RNA was observed in the peri-necrosis and ipsilateral thalamus regions, while L-ferritin messenger RNA was noted exclusively at the edge within the necrosis. Results of immunohistochemical study further revealed that ferritin immunoreactivity was present in the same areas where increased ferritin messenger RNA was found. Sixty-minute ischemia also led to iron deposition in discrete areas. Iron deposition was highly associated with the induction of ferritin, particularly in the macrophage- and microglia-positive areas where cell death or tissue necrosis was noted.In summary, our initial findings indicate that ischemic insult leads to induction of both H- and L-ferritin messenger RNA. In the present study, although the temporal induction profiles were similar, the major expression areas for these two genes were totally different. Ferritin immunoreactivity was observed in the same areas where increased ferritin messenger RNA was found. Ischemia also resulted in iron deposition, which highly associated with the ferritin immunoreactivity. The exact regulatory mechanism and pathological significance for the differential expression of H- and L-ferritin genes following ischemia/reperfusion remain to be clarified.

Animals↗

PubMed1987

Siderosomal ferritin. The missing link between ferritin and haemosiderin?

A minor electrophoretically fast component was found in ferritin from iron-loaded rat liver in addition to a major electrophoretically slow ferritin similar to that observed in control rats. The electrophoretically fast ferritin showed immunological identity with the slow component, but on electrophoresis in SDS it gave a peptide of 17.3 kDa, in contrast with the electrophoretically slow ferritin, which gave a major band corresponding to the L-subunit (20.7 kDa). Thus the electrophoretically fast ferritin resembles that reported by Massover [(1985) Biochim. Biophys. Acta 829, 377-386] in livers of mice with short-term parenteral iron overload. The electrophoretically fast ferritin had a lower iron content (2000 Fe atoms/molecule) than the electrophoretically slow ferritin (3000 Fe atoms/molecule). Removal and re-incorporation of iron was possible without effect on the electrophoretic mobility of either ferritin species. On subcellular fractionation the electrophoretically fast ferritin was enriched in pellet fractions and was the sole soluble ferritin isolated from iron-laden secondary lysosomes (siderosomes). The amount and relative proportion of the electrophoretically fast species increased with iron loading. Haemosiderin isolated from siderosomes was found to contain a peptide reactive to anti-ferritin serum and corresponding to the 17.3 kDa peptide of the electrophoretically fast ferritin species. Unlike the electrophoretically slow ferritin, the electrophoretically fast ferritin did not become significantly radioactive in a 1 h biosynthetic labelling experiment. We conclude that the minor ferritin is not, as has been suggested for mouse liver ferritin, 'a completely new species of smaller holoferritin that represents a shift in the ferritin phenotype' in response to siderosis, but a precursor of haemosiderin, in agreement with the proposal by Richter [(1984) Lab. Invest. 50, 26-35] concerning siderosomal ferritin.

Animals↗

PubMed1989

Purification of chicken liver ferritin by two novel methods and structural comparison with horse spleen ferritin.

Ferritin was purified from chicken liver by two different methods: gel filtration on controlled-pore glass beads, and immunoaffinity chromatography employing a chicken ferritin-specific monoclonal antibody that did not cross-react with horse spleen ferritin. This antibody recognizes intact ferritin and an oligomeric 240 kDa form of the molecule after protein transfer to nitrocellulose, but not the 22 kDa chicken ferritin subunit. Chicken liver ferritin purified by these methods exhibited reduced migration on non-denaturing polyacrylamide gels compared with horse spleen ferritin. These results were consistent with the difference in calculated isoelectric points of chicken and horse ferritin subunits. By two-dimensional gel electrophoresis, chicken ferritin 22 kDa subunits exhibited isoelectric points from 6.1 to 6.6 whereas horse spleen ferritin subunits exhibited isoelectric points of 5.8-6.3. The 240 kDa form of the chicken ferritin molecule had an isoelectric point of 6.6 whereas the 210 kDa form of the horse ferritin molecule had isoelectric points of 5.1 and 4.9. Intact chicken liver ferritin particles were 13.4 +/- 0.8 nm (controlled-pore glass-purified) and 12.5 +/- 0.9 nm (affinity-purified) in diameter when viewed by electron microscopy. Horse spleen ferritin consisted of slightly smaller particles with an average diameter of 11.0 +/- 0.7 nm. However, ferritin from chicken liver and horse spleen co-migrated with an apparent molecular mass of 470 kDa when analysed by Sepharose 4B gel filtration chromatography. These results indicate that, consistent with results from other published purification methods, the chicken ferritin purified by the methods reported here exhibits both structural similarities to, and differences from, horse spleen ferritin.

Animals↗

PubMed1991

[Ferritin in acute leukemia. Serum ferritin concentration as a nonspecific tumor marker for M1 and M2 myeloid leukemia].

Serum ferritin concentration was studied in 136 patients with different types of acute leukemia. Pretreatment serum ferritin concentrations in the immature myeloblastic leukemia (M1 and M2 of the FAB-classification of acute leukemias) was found to be highly increased compared to the more mature types of acute myeloblastic leukemias (M3 to M5) and the acute lymphoblastic leukemias (L1 to L3). Investigation of the intracellular ferritin concentration showed, that the serum ferritin levels paralleled the intracellular ferritin concentration within the leukemic blasts. Within the immature myeloic blasts (M1) the intracellular ferritin concentration was 14-fold increased compared to normal granulocytes. This correlated with the 17-fold increased serum ferritin levels in these patients. Intracellular ferritin concentrations within the leukemic blasts of more mature types of acute leukemia (M3 to M5) were found to be only slightly increased. These data support the concept, that an increased synthesis and release of ferritin by the leukemic blasts is responsible for the increased serum ferritin concentration. This concept is also supported by the observation, that a further increase of serum ferritin concentration was seen during a cytotoxic chemotherapy. It is noteworthy, that this increase was more pronounced in the immature leukemias obviously caused by a loss of intracellular ferritin from the damaged leukemic blasts. The serum ferritin levels followed closely the activity of the disease. Increased pretreatment serum ferritin concentrations normalized completely when patients achieved complete remission. In contrast, in patients with tumor relapse or tumor progression serum ferritin concentrations increased again. These data suggest that the serum ferritin in immature myeloblastic leukemia has the characteristics of a tumor associated marker.(ABSTRACT TRUNCATED AT 250 WORDS)

Biomarkers, Tumor↗

PubMed1987

Differences in the regulation of messenger RNA for housekeeping and specialized-cell ferritin. A comparison of three distinct ferritin complementary DNAs, the corresponding subunits, and identification of the first processed in amphibia.

The ferritin family is a widespread group of proteins that maintain iron in a soluble form and also protect against the toxic effects of excess iron. The structure and sequence of the proteins are highly conserved. However, the cell-specific features of structure which occur within the same organism indicate cell specificity of gene expression and may be related to variations in types of iron storage, i.e. specialized-cell ferritin (stored iron is for other cell types) versus housekeeping ferritin (stored iron is for intracellular purposes related to normal or stress metabolism); the protein structure may also affect rates of iron turnover. Iron induces ferritin synthesis and accumulation by recruiting stored ferritin mRNA that is efficiently translated in cells specialized for iron storage. For the first time we show the occurrence of three different cDNAs from bullfrog tadpoles, corresponding to three subunits of the protein: H, M, and L. Thus, ferritin can be encoded by at least three different mRNAs and probably three different genes, in contrast to the older idea of two, H and L; the subunits maintain the conserved sequences of known ferritins and have similar predicted masses, 20.5, 20.6, and 19.9 kDa, but have distinct mobilities in denaturing gels. Ferritin subunit expression is cell specific; more of the H and L chain mRNAs are expressed in red cells than in liver. Ferritin expression is regulated by transcription (or mRNA stability) in adult red cells; cellular levels of ferritin mRNA were 20% that of embryonic red cells, and L subunit mRNA increased 2.5 times with excess iron. Ferritin expression is also regulated during translation in adult red cells; iron recruits stored ferritin mRNA, but only during certain stages of red cell maturation, in contrast to embryonic red cells. The developmental differences in ferritin expression are discussed in relation to the shift from specialized-cell ferritin to housekeeping ferritin in red cells of the embryonic versus adult lines.

Amino Acid Sequence↗

PubMed1979

Characterization of ferritin from human placenta. Implications for analysis of tissue specificity and microheterogeneity of ferritins.

Mammalian ferritins can be resolved into multiple components by isoelectric focusing, and each tissue contains a characteristic subset of isoferritins. Ferritin isolated from human liver was compared to acidic ferritin isolated from mid-gestational human placenta to define a structural basis for ferritin heterogeneity. Placenta ferritin contained several major bands with isoelectric points in the range of pI = 4.7-5.0 which were more acidic than the predominant isoferritins of human liver. Ferritin from each tissue was resistant to denaturation by 10 M urea and appeared to be identical by electron microscopy. Circular dichroism measurements revealed that placenta ferritin had substantially less ordered secondary structure than liver ferritin. Both types of ferritin contained only two subunits when analyzed by electrophoresis in sodium dodecyl sulfate gels, but isoelectric focusing of dissociated subunits in urea revealed 6-7 different components. In this system, placenta ferritin was enriched in the more acidic subunits and it completely lacked the most basic subunits noted in liver ferritin; placental ferritin had no unique components. Differences in isoelectric points among assembled ferritins from these two tissues appear to result from different proportions of these acidic and basic subunits.

Chemical Phenomena↗

PubMed2000

Characterization of ferritin and ferritin-binding proteins in canine serum.

Ferritin and ferritin-binding proteins in canine serum were characterized. A certain percentage of ferritin in canine serum, but no tissue ferritin, was precipitated by centrifugation at 16,000 x g for 30 min. The precipitated ferritin was found to contain two subunits corresponding to the H and L subunits of canine liver ferritin by immunoblotting, the H subunit being predominant. More ferritin was precipitated from canine sera which had been incubated with anti-rat liver ferritin antibody than from untreated sera, and the H chain also predominated. To evaluate the possibility that the autoantibody was responsible for the precipitation of canine serum ferritin, the ferritin-binding activities of canine antibodies were examined using liver ferritin-coated microtiter plates and alkaline phosphatase-labeled antibodies specific for canine IgM, IgA, and IgG heavy chains. The results showed that IgM and IgA, but not IgG, had considerable ferritin-binding activities. Given these results, we suggest that there is H-chain-rich isoferritin in canine serum, and that ferritin exists as an immune complex.

Animals↗

PubMed2001

Cationic ferritin changes outflow facility in human eyes whereas anionic ferritin does not.

PURPOSE: To determine the effect of charged moieties within the outflow pathway on aqueous outflow facility in human eyes. METHODS: After baseline facility measurement in human eye bank eyes (n = 10 pairs), one eye of each pair received anterior chamber exchange and continued perfusion with medium containing 10 mg/ml cationic ferritin. Contralateral eyes were treated in a similar manner with anionic ferritin (10.0 or 102 mg/ml). Eyes were fixed by anterior chamber exchange and perfusion with universal fixative at 8 mm Hg (corresponding to a physiologic pressure of 15 mm Hg in vivo) and examined by transmission electron microscopy. In a second series of human eyes (n = 8 pairs), facility was measured before and after anterior chamber exchange, with a solution containing 0.1 U/ml neuraminidase. RESULTS: Perfusion of eyes with anionic ferritin at either 10.0 or 102 mg/ml caused a negligible 2% increase in facility, whereas cationic ferritin perfusion reduced facility by 66% (P < 0.00001). Perfusion with fixative reduced facility by approximately 60% in both cationic and anionic ferritin-perfused eyes, relative to facilities after perfusion with ferritin. Transmission electron microscopy showed that the distribution of ferritin was segmentally variable. Cationic ferritin consistently labeled the luminal surface of the inner wall of Schlemm's canal, and variably labeled the juxtacanalicular connective tissue (JCT) and trabecular beam surfaces. Anionic ferritin was more prominent in the JCT and intertrabecular spaces and less so on the luminal surface of Schlemm's canal. By scanning electron microscopy, cationic ferritin was seen to accumulate at intercellular margins of the inner wall. Neuraminidase perfusion had no significant effect on outflow facility. CONCLUSIONS: Cationic ferritin reduces outflow facility, presumably by binding to negatively charged sites in the outflow pathway. A possible mechanism is partial or complete blockage of intercellular clefts in the inner wall of Schlemm's canal by the ferritin that accumulates on the luminal surface of the inner wall. Although they are possible targets for ferritin binding, sialyl residues themselves seem to have little direct effect on outflow facility. Our data indicate that positively charged molecules, especially if they can interact with inner wall pores, have the potential to markedly alter outflow facility.

Adult↗

PubMed1990

Examination of serum ferritin and erythrocyte ferritin--its role in the blood transfusion service.

Blood donors were examined for serum ferritin values and concentration of ferritin in the erythrocytes. The group of male and female donors without previous donations showed average values of 102.27 ng and 51.75 ng of ferritin per one ml of serum, respectively. Males with over 20 donations had 68.04 ng ferritin per one ml, females 37.14 ng of ferritin per one ml. The reduced serum ferritin values in multiple male and female donors is statistically significant. Serum ferritin values in women of the two groups are lower than those of males, the difference also being statistically significant. In male and female blood donors, irrespective of the number of donations, average values of 13.74 ag and 12.07 ag of ferritin per erythrocyte, respectively, were established. The difference in ferritin concentration in the erythrocytes between males and females is statistically insignificant. The correlation coefficient failed to demonstrate any dependence between erythrocyte ferritin concentration and concentration of ferritin in the serum. The object of serum ferritin determination in blood donors is to detect the earliest stage of storage iron deficiency in the organism. For the latter purpose, the determination of erythrocyte ferritin is ineffective.

Blood Donors↗