Ferritin: structure, synthesis and function

Genome-wide DNA methylation sequencing reveals the involvement of ferroptosis in hepatotoxicity induced by dietary exposure to food-grade titanium dioxide

BACKGROUND

Following the announcement by the European Food Safety Authority that the food additive titanium dioxide (E 171) is unsafe for human consumption, and the subsequent ban by the European Commission, concerns have intensified over the potential risks E 171 poses to human vital organs. The liver is the main organ for food-grade nanoparticle metabolism. It is increasingly being found that epigenetic changes may play an important role in nanomaterial-induced hepatotoxicity. However, the profound effects of E 171 on the liver, especially at the epigenetic level, remain largely unknown.

METHODS

Mice were exposed orally to human-relevant doses of two types of E 171 mixed in diet for 28 and/or 84 days. Conventional toxicology and global DNA methylation analyses were performed to assess E 171-induced hepatotoxicity and epigenetic changes. Whole genome bisulfite sequencing and further ferroptosis protein detection were used to reveal E 171-induced changes in liver methylation profiles and toxic mechanisms.

RESULTS

Exposed to E 171 for 28 and/or 84 days resulted in reduced global DNA methylation and hydroxymethylation in the liver of mice. E 171 exposure for 84 days elicited inflammation and damage in the mouse liver, whereas 28-day exposure did not. Whole-genome DNA methylation sequencing disclosed substantial methylation alterations at the CG and non-CG sites of the liver DNA in mice exposed to E 171 for 84 days. Mechanistic analysis of the DNA methylation alterations indicated that ferroptosis contributed to the liver toxicity induced by E 171. E 171-induced DNA methylation changes triggered NCOA4-mediated ferritinophagy, attenuated the protein levels of GPX4, FTH1, and FTL in the liver, and thereby caused ferroptosis.

CONCLUSIONS

Long-term oral exposure to E 171 triggers hepatotoxicity and induces methylation changes in both CG and non-CG sites of liver DNA. These epigenetic alterations activate ferroptosis in the liver through NCOA4-mediated ferritinophagy, highlighting the role of DNA methylation and ferroptosis in the potential toxicity caused by E 171 in vivo.

Cell-Free Protein Synthesis of Metalloproteins

Metalloproteins, proteins containing metal atoms or clusters within their structures, are critical for various biological functions across all domains of life. More than hundreds of different types have been discovered, which conduct various roles such as transportation of O2, catalyzing chemical reactions, sensing environmental changes, and relaying electrons. Metalloprotein molecules incorporate a variety of metal atoms, coordinated to specific amino acid residues that affect their conformation and functionality. The process of metal incorporation typically occurs during or post-protein folding, often requiring chaperones for metal ion delivery and quality control. Progress in understanding metal incorporation and metalloprotein functionality has been enhanced by cell-free protein synthesis (CFPS) methods that offer direct control over the synthesis environment. This chapter reviews the diverse applications of CFPS methods in metalloprotein research, encompassing structure-function studies, protein engineering, and creation of artificial metalloproteins. Examples demonstrating the utility and advances brought about by CFPS in synthetic biology, electrochemistry, and drug discovery are highlighted. Despite remarkable progress, challenges remain in optimizing and advancing the CFPS methods, underscoring the need for future explorations in this transformative approach to metalloprotein study and engineering.

An Indian Desert Shrub 'Hiran Chabba', Farsetia hamiltonii Royle, Exhibits Potent Antioxidant and Hepatoprotective Effect Against Iron- Overload Induced Liver Toxicity in Swiss Albino Mice

BACKGROUND

Farsetia hamiltonii Royle, also known as Hiran Chabba grows in desert regions. It is widely used as folk medicine to treat joint pains, diarrhea and diabetes. However, its antioxidant and iron chelation abilities both in vitro and in vivo have not yet been investigated.

METHODS

The 70% methanolic extract of F. hamiltonii (FHME) was investigated for its free radical scavenging and iron chelation potential, in vitro. An iron-overload situation was established by intraperitoneal injection of iron-dextran in Swiss albino mice, followed by oral administration of FHME. Liver damage and serum parameters due to iron-overload were measured biochemically and histopathologically to test iron-overload remediation and hepatoprotective potential of FHME. Phytochemical analyses were performed to determine its probable bioactive components.

RESULTS

FHME showed promising antioxidant activity, scavenged various reactive oxygen and nitrogen species and chelated iron in vitro. FHME reduced liver iron, serum ferritin, normalized serum parameters, reduced oxidative stress in liver, serum and improved liver antioxidant status in ironoverloaded mice. It also alleviated liver damage and fibrosis as evident from biochemical parameters and morphological analysis of liver sections. The phytochemical analyses of FHME reflected the presence of alkaloids, phenols, flavonoids and tannins. HPLC analysis indicated presence of tannic acid, quercetin, methyl gallate, catechin, reserpine, ascorbic acid and gallic acid.

CONCLUSION

Based on the experimental outcome, FHME, an ethnologically important plant can be envisaged as excellent antioxidant and iron chelator drug capable of remediating iron-overload induced hepatotoxicity and the bioactive compounds present in FHME might be responsible for its efficacy.

Watch What You (Self-) Eat: Autophagic Mechanisms that Modulate Metabolism

Autophagy is an evolutionarily conserved lysosome- or vacuole-dependent catabolic pathway in eukaryotes. Autophagy functions basally for cellular quality control and is induced to act as an alternative source of basic metabolites during nutrient deprivation. These functions of autophagy are intimately connected to the regulation of metabolism, and the metabolic status of the cell in turn controls the nature and extent of autophagic induction. Here, we highlight the co-regulation of autophagy and metabolism with a special focus on selective autophagy that, along with bulk autophagy, plays a central role in regulating and rewiring metabolic circuits. We outline the metabolic signals that activate these pathways, the mechanisms involved, and the downstream effects and implications while recognizing yet unanswered questions. We also discuss the role of autophagy in the development and maintenance of adipose tissue, an emerging player in systemic metabolic homeostasis, and describe what is currently known about the complex relationship between autophagy and cancer.

Hepcidin levels in hereditary hyperferritinemia: Insights into the iron-sensing mechanism in hepatocytes

AIM: To study the role of hepcidin in hereditary hyperferritinemia cataract syndrome (HHCS).

METHODS: Six patients from two families with HHCS, confirmed by genetic analysis showing A to G mutation at position +40 in the L-ferritin gene, were recruited to undergo serum hepcidin and prohepcidin measurements using radioimmunoassay and enzyme linked immunoassay, respectively, and measurements were compared with levels in serum from 25 healthy volunteers (14 females), mean age 36 ± 11.9 years.

RESULTS: The serum hepcidin and prohepcidin levels in patients with HHCS were 19.1 ± 18.6 and 187 ± 120.9 ng/mL, respectively. Serum ferritin was 1716.3 ± 376 μg/L. Liver biopsy in one patient did not show any evidence of iron overload. Serum hepcidin and prohepcidin values in healthy controls (HCs) were 15.30 ± 15.71 and 236.88 ± 83.68 ng/mL, respectively, while serum ferritin was 110 ± 128.08 μg/L. There was no statistical difference in serum hepcidin level between the two cohorts (19.1 ± 18.6 ng/mL vs 15.30 ± 15.71 ng/mL, P = 0.612) using two-tailed t-test.

CONCLUSION: Serum hepcidin levels in HHCS patients is similar to that in HCs. Our study suggests that circulating ferritin is not a factor influencing hepcidin synthesis and does not have a role in the iron-sensing mechanism in hepatocytes.

Supplemental dietary inulin influences expression of iron and inflammation related genes in young pigs

We have previously shown improved hemoglobin (Hb) repletion efficiency by supplementing a 50:50 mixture of short (P95) and long-chain (HP) inulin (Synergy 1, BENEO-Orafti) into a corn-soybean meal-basal diet (BD) for young pigs. In this study, weanling pigs (5 or 6 wk old) were fed the BD or the BD + 4% of P95, HP, or Synergy 1 (50:50 mixtures of HP and P95) for 5-7 wk. Blood Hb concentrations of pigs were measured weekly and digesta samples were collected at the end of the trial. In a replicate experiment, total RNA was isolated from the liver and mucosa of duodenum, ileum, cecum, and colon of all pigs at the end of the trial. Relative mRNA expression of 27 genes, including iron and inflammation-related genes, was quantified using real-time quantitative-PCR. Although all 3 types of inulin resulted in similar improvements (P < 0.05) in blood Hb concentration and liver ferritin protein amount, neither type of inulin was detectable in the digesta of cecum or colon. Supplemental inulin enhanced the expression of iron-storing protein genes but decreased that of inflammation-related genes. Such effects were more pronounced (P < 0.05) in the mucosa of the lower than the upper gut and were seen on 7 genes in liver. In conclusion, all 3 types of inulin shared similar efficacy and possibly similar modes of action in improving dietary iron utilization by young pigs. Suppressing inflammation-induced genes that can negatively influence iron metabolism might help explain the benefit of inulin.

Quantification of cerebrospinal fluid ferritin as a biomarker for CNS malignant infiltration

Several markers have been studied for their ability to make the CNS infiltration diagnosis earlier and more precise; previous studies showed that CSF ferritin concentrations were higher in patients with malignant invasion of CNS. The objective was to determine the importance of CSF ferritin as a biomarker for the diagnosis of CNS neoplastic infiltration. This study is based on 93 CSF samples, divided into five groups: malignant cells present (n13); malignant cells not present (n26); inflammatory neurological diseases (n16); neurocysticercosis (n20); acute bacterial meningitis (n18). CSF ferritin values were determined by micro particle enzyme immunoassay. CSF ferritin level (mean+/-SD) in the group with neoplastic cells in the CSF was 42.8+/-49.7 ng/mL, higher than in the other groups (p<0.0001). We conclude that CSF ferritin with the cut off 20 ng/mL could be an adjuvant biomarker to the diagnosis of CNS malignant infiltration.

Ultrastructural study of erythrophagocytosis in the rat bone marrow II. Iron metabolism in reticulum cells following red cell digestion

Intracellular transport and storage of iron in bone marrow reticulum cells can be studied in the electron microscope by the recognition of iron macromolecules. Following artificially increased bone marrow erythrophagocytosis ferritin molecules accumulate both in the cell sap and in the lysosomes of erythroclastic reticulum cells. Persistent iron loading transforms lysossomes into siderosomes, after which haemosiderin may be formed by grandual transformation of ferritin. The bone marrow reticulum cell shows evidence suggestive of autophagy, a process which may allow for the transfer of cell sap ferritin into lysosomes, as documented for other types of iron storing cells.

Reference ranges for serum concentrations of lutropin (LH), follitropin (FSH), estradiol (E2), prolactin, progesterone, sex hormone-binding globulin (SHBG), dehydroepiandrosterone sulfate (DHEAS), cortisol and ferritin in neonates, children and young adults

The aim of this study was to establish reference ranges for children (neonates to young adults), for serum lutropin (LH), follitropin (FSH), estradiol (E2), progesterone, prolactin, sex hormone-binding globulin (SHBG), dehydroepiandrosterone sulfate (DHEAS), cortisol and ferritin, using the nonisotopic, automated chemiluminescence immunoassay system, Immulite (DPC). Serum samples from 762 children (369 female; age 1 day to 19 years) were examined. Of these, 381 were classified as pubertal. Due to non-normal distribution, the 2.5th, 50th and 97.5th percentiles (central 95% interval) were calculated for each group. Statistical differences between the reference ranges were analyzed with respect to age, sex and the stage of sexual maturation. The median concentrations of E2, prolactin, progesterone, DHEAS, cortisol and ferritin were higher during the first 2 weeks post-partum than thereafter. The largest difference was seen with prolactin, which showed up to 27-fold higher values during this period. In contrast, before the onset of puberty, hardly any sex difference was observed and all analyte concentrations remained relatively constant, apart from SHBG which increased steadily after the neonatal period. The increase of gonadal activity in females with the onset of sexual maturation included an increase in LH and FSH, which was accompanied by a strong increase in E2, progesterone and prolactin. Cortisol increased to a lesser extent during puberty. In males, the increase in the median concentrations of the hormones was smaller, except for DHEAS. The concentration of ferritin was high in the neonatal period but did not change during sexual maturation. Our findings agree with earlier studies. The calculated reference intervals can be used to assess the development of children, particularly for measurements performed by the Immulite and Immulite 2000 chemiluminescence assay systems.

Purification and characterization of liver ferritins from different animal species

The ferritins were purified from liver homogenates of buffalo, camel, cattle, sheep and shark by thermal denaturation, ammonium sulphate fractionation, Sephacryl S-300 gel filtration and DEAE-blue gel affinity chromatography. The yield and iron content of affinity-purified liver ferritins ranged from 0.008 to 0.052 mg/g and 3.17% to 11.4% respectively. As they are glycoproteins, the ferritins contained variable amounts of neutral carbohydrates. Except for shark ferritin, the ferritins all exhibited immunological cross-reactivity with anti-buffalo liver ferritin and anti-horse spleen ferritin by immunodiffusion and immunoelectrophoresis. Gel electrophoresis, gel filtration and ultracentrifugal analysis indicated the presence of a monomeric ferritin in all cases. SDS-gel electrophoresis of shark ferritin gave a protein band of 18 kDa. Ovine, buffalo and bovine ferritin comprised two protein subunits, the H (20 and 21 kDa) and the L types (18 and 19 kDa). Oligomeric ferritin subunits with molecular weights of 27, 37 and 55 kDa were also found for bovine and buffalo ferritin. SDS-PAGE of camel ferritin revealed a complex pattern with four prominent bands of 61, 51, 44 and 39 kDa. Two fast-migrating components of 15 and 16 kDa were also found in the purified liver ferritins, including reference preparations. The PO4(3-)/Fe ratios of purified shark (0.10) and bovine ferritin (0.12) were similar to that of standard equine spleen ferritin (0.11). However, the ratio was higher in ovine (0.17), camel (0.22) and bovine (0.26) ferritins. The amino acid compositions, molecular weights and sedimentation coefficients of the different liver ferritins were similar.

Comparative clinical evaluation of biochemical and genomic tumor markers

The clinical utilities of established biochemical tumor markers and of emerging genomic markers are compared by six formal criteria: [1] tests negative in health or benign disease, [2] produced exclusively by specific tumor cells, [3] present frequently in the targeted malignancy, [4] detectable in occult disease, [5] degree of expression reflects tumor burden and prognosis, and [6] degree of expression correlates with therapeutic result. Evaluation of eight widely accepted marker systems combining a biochemical indicator with a specific cancer, on the one hand, and five representative genomic marker-target combinations involving chromosomal translocation, gene amplification and mutation, on the other hand, produces three main conclusions: First, specified applications are sufficiently well documented for the best biochemical markers to now tailor analytical performance goals to these uses. Second, further clinical trials of genomic markers are needed to document the useful linkage of specific indicators with specific clinical problems. Third, the different profiles of marker characteristics defining the two classes of indicators suggest some mutually complementary uses.

Serum tumor markers of head and neck cancer: current status

The serum level of a variety of substances shows significant changes in head and neck cancer patients. Such substances are collectively called biochemical tumor markers. To date, most markers lack a high degree of specificity and sensitivity. However, serial measurement of markers showing elevated pretreatment levels may help in monitoring response to therapy. Other potential uses of tumor markers include earlier detection of recurrence and/or metastasis, and possible prediction of prognosis. Measurement of more than one marker seems to enhance the diagnostic accuracy of the test. Some markers show significant correlations with various immune parameters in head and neck cancer patients and may have a possible role in potentiating the immunodepressed status of such patients. A review of currently reported tumor markers in head and neck cancer showing their nature, sources, uses, and limitations is presented.

A longitudinal study of serum ferritin concentration during the female adolescent growth spurt

An 8-year longitudinal study of changes in serum ferritin concentration has been carried out with additional measurements of haemoglobin and serum iron in 39 schoolgirls aged 10 years at entry to the study. This laboratory data was analysed in relation to menarche and stature. The mean serum ferritin concentration declined significantly due to the occurrence of menarch, rather than to a growth spurt and showed the lowest level at the third year after menarche. Thereafter, it increased again. The prevalence of schoolgirls with latent iron deficiency, defined by a low serum ferritin concentration, normal haemoglobin and normal serum iron concentration, also increased after menarche, and reached its highest level (71.8%) at the third year after menarche. Although haemoglobin and iron concentration declined after menarche, these changes were not statistically significant except for haemoglobin at the second year after menarche. These findings show that serum ferritin concentration is a sensitive variable, and indicates that latent iron deficiency follows menarche rather than an increase in height velocity in adolescence.

A long term survey of plasma and tissue ferritin in mice fed on iron deficient diets

1. Changes in plasma and tissue ferritin concentrations were surveyed in mice fed on iron deficient diets (Fe, 2.4 micrograms/g) from the age of 8 to 30 weeks by an enzyme-immunoassay for mouse ferritin. Values were compared with those in mice on control diets (Fe, 110 micrograms/g) and mice with blood loss. 2. In mice on iron deficient diets, while plasma ferritin remained at normal level, ferritin in the spleen and kidney decreased, but that in the liver increased as much as twice of that in the control. 3. Mice with blood loss revealed a drastic reduction of ferritin in every tissue and plasma examined.

The origin of increased serum iron in pregnancy-induced hypertension

Serum iron was measured in 30 patients with pregnancy-induced hypertension and 24 normal pregnant women. The mean iron concentration was significantly higher in the group with pregnancy-induced hypertension (111 +/- 26 micrograms/ml) than in the controls (69 +/- 17 micrograms/ml) (p less than 0.0001). Readily available laboratory variables were used to determine whether the increased serum iron was the result of (1) hemolysis, (2) hepatocellular injury, or (3) intravascular volume contraction leading to hemoconcentration. It appears that a clinically silent, ongoing hemolytic reaction is responsible for the increase in serum iron seen in patients with pregnancy-induced hypertension.

Determination of iron to phosphorus ratios of iron storage compounds in patients with iron overload: a chemical and electron probe X-ray microanalysis

The amounts of phosphorus and iron in various isolated ferritin preparations were investigated by: chemical analysis on ferritin samples and electron probe X-ray microanalysis on ferritin particles from the same preparations. A high correlation was found between iron to phosphorus ratios obtained by both methods. Further investigation by electron probe X-ray microanalysis on lysosomes of hepatic cells of patients with idiopathic and secondary hemochromatosis revealed lysosomal iron to phosphorus ratios which were very similar in all parenchymal cells but different from ratios obtained in Kupffer cells. Lysosomal iron to phosphorus ratios in hepatocytes did not change after intensive phlebotomy treatment. It is postulated therefore that, during phlebotomy, iron and phosphorus are concomitantly lost from the hepatic lysosomes.

Serum ferritin levels in small cell lung cancer

Serum ferritin levels were measured before treatment, using an immunoradiometric method, in 39 patients with small cell lung cancer. In 11 patients serial estimations were also made. The median serum ferritin level for male patients was 660 micrograms/l (range 13-1329) and for females 306 (range 134-5300), the normal range being 32-501. This increase is significant (P less than 0.001). Serum ferritin levels were not related to metastatic, haematological or iron status. Serial ferritin levels did not reflect the clinical course of the disease. Patients with a pre-treatment serum ferritin of less than 600 micrograms/l had a significant prolongation of median survival compared to those with an initial serum ferritin of greater than 600 micrograms/l (P less than 0.02). Serum ferritin levels are not of value in staging small cell lung cancer nor in monitoring its progress. However, the initial serum ferritin is of prognostic significance.

Tumor markers: value and limitations in the management of cancer patients

Sixteen tumor markers are reviewed, and measured to the ideal: produced by the tumor cell alone absent in health and in benign disease present in all patients with a given malignancy level in the blood representative of tumor mass detectable in occult disease. The only marker that approaches the ideal is human chorionic gonadotropin (HCG) in gestational trophoblastic tumors. In this malignancy, the HCG level suggests the diagnosis and stage, confirms response to therapy, and predicts relapse. The three most widely used and intensely studied tumor markers are carcinoembryonic antigen (CEA), alphafetoprotein (AFP), and HCG. CEA cannot be used in screening for cancer, but in carcinoma of the colon its elevation preoperatively increases the likelihood of advanced disease and postoperative recurrence. Postoperatively, elevated titers are often but not invariably associated with recurrent disease. AFP and HCG are useful in the management of nonseminomatous germ cell testicular tumors. Like CEA, they cannot be used for screening. They are more likely to be increased with advancing stage, and after therapy rising levels almost always mean recurrent disease. Some markers are valuable in specific circumstances, such as calcitonin in screening for familial medullary carcinoma of the thyroid. In multiple myeloma, immunoglobulins are useful in determining the tumor mass and response to therapy. In neuroblastoma, catecholamine metabolites are useful primarily in making the diagnosis. In some malignancies, the absence of effective therapy lowers the value of the marker, as for AFP in hepatoma. The remaining markers are too unreliable or too little studied to be useful in the management of an individual patient with cancer. The purpose of this paper is to provide the clinician with an understanding of the limitations of the present tumor markers that will lead to wiser use of the tests, and to provide standards to which future tumor markers should be measured.

Elevated serum ferritin in the altered ferrokinetics of toxemia of pregnancy

The serum concentration of ferritin in 11 patients with toxemia of pregnancy was compared to that of normal women in the early third trimester of pregnancy and in labor at term. The mean concentration of ferritin for toxemic patients was 91.8 ng/ml compared to 18.4 ng/ml and 19.4 ng/ml for the two control groups, respectively. The biochemical and physiologic features of ferritin are reviewed, and the relationship between iron and ferritin is discussed. Despite elevated serum levels of ferritin in toxemia, it is noted to be less reflective of the clinical course of the syndrome than serum ion.

Major factors limiting sensitivity of sandwich enzyme immunoassay for ferritin, immunoglobulin E, and thyroid-stimulating hormone

By using IgG-coated polystyrene balls and beta-D-galactosidase-labelled Fab', sandwich enzyme immunoassays for human ferritin, immunoglobulin E (IgE), and thyroid-stimulating hormone (TSH) were developed, and their sensitivities were shown to be largely limited by the purity, binding efficiency, and amount of beta-D-galactosidase-labelled Fab' used. (1) Their sensitivities were enhanced 10 to 50-fold by using affinity-purified Fab' labelled with beta-D-galactosidase. (2) Their sensitivities depended upon the efficiency of specific binding of the labelled Fab' to antigens adsorbed on antibody IgG-coated polystyrene balls. (3) Their sensitivities were improved by using the minimal amount of labelled Fab' that gave a reliable calibration curve. Under optimal conditions the sensitivities obtained for ferritin, IgE, and TSH were 0.09 pg (0.2 amol), 0.48 pg (2.4 amol, 0.2 mIU), and 3.2 millimicronU (5.7 amol) per tube, respectively.

Failure of serum ferritin levels to predict bone-marrow iron content after intravenous iron-dextran therapy

The relation between serum ferritin levels and stainable-iron deposits in the liver, spleen, and bone marrow was investigated in 36 patients with chronic renal failure who died after being on haemodialysis for 1-103 months. Elemental iron (mean, 5450 mg) had been given intravenously as iron dextran to patients in a long-term subgroup, who had been on dialysis for more than 3 months. The results of semiquantitative histochemical assessment of tissue iron in slides obtained at necropsy (scale 0 to 4+) were confirmed by chemical analyses of tissue iron. Serum ferritin levels correlated well with the degree of hepatosplenic siderosis but did not always correlate with bone-marrow iron stores in these patients. Serum ferritin concentrations were raised in 10 marrow-iron-depleted subjects (mean, 1336 ng/dl). The paradoxical association of hepatosplenic siderosis with marrow iron depletion was observed in most of the patients on dialysis for less than 40 months. The histochemical data show that the bulk of intravenously injected iron dextran is taken up by the liver and spleen; that the hepatosplenic stores fail to be mobilised to the bone marrow; and that intravenous iron-dextran therapy, by-passing the intestinal mechanism for the regulation of iron absorption, carries a high risk of long-term hepatosplenic siderosis.

Electron-probe x-ray analysis of granules and particles found in aurosomes produced by colloidal gold

Aurosomes produced in the rabbit synovial membrane after intraarticular injection of colloidal gold were found to contain large spherical electron-dense granules and fine electron-dense particles. Electron-probe x-ray analysis demonstrated the presence of gold in the granules and iron in the particles. Sulphur and phosphorus were not detected in these aurosomes produced by colloidal gold. This is in contrast to the aurosomes produced by the soluble gold salt sodium aurothiomalate where besides gold, sulphur and phosphorus are easily detected.

Ultrastructural localization and in situ analysis of iron, bismuth, and gold inclusions

The purpose of this article is to review ultrastructural and electron probe X-ray analytical studies on metallic deposits in cells. The metals that will be dealt with are iron, bismuth, and gold, mainly because they have been extensively studied in recent years. The nature and chemical composition of endogenously (e.g., from breakdown of autologous blood) and exogenously (e.g., after a transfusion or injection of iron compounds) produced hemosiderin (i.e., iron deposits) has been the subject of time-hallowed controversies. Quite a few of these have now been resolved by ultrastructural studies and the atomic composition of such deposits has been determined by electron probe X-ray analysis. The interest in bismuth centers around the fact that this is one of the two metals (the other being lead) that produces quite large intranuclear inclusions. Here again much has been learned by ultrastructural and X-ray analytical studies. The interest in gold stems from the fact that soluble salts of this metal are used for the treatment of rheumatoid arthritis and current studies with the above-mentioned techniques indicates how gold produces its beneficial and toxic effects.

Immunoradiometric and electroimmuno assay of increased ferritin and apoferritin levels in serum

Ferritin in serum from patients with increased serum ferritin levels has been studied both quantitatively and qualitatively. All techniques utilized in these studies are suitable to be used as routine screening tests for large numbers of patients. Electroimmuno assay (EIA) has been compared with the solid phase immunoradiometric (IRMA) assay as a technique to determine serum ferritin concentration (r = 0.99) and is suggested as a useful alternative when determining ferritin concentrations above 500 microgram/l. Iron stained EIA gels have been used to indicate the iron content of the ferritin molecule in sera. This simple screening test has demonstrated that apoferritin is found more often than iron-rich ferritin in the serum of patients with elevated serum ferritin levels. Immunoelectrophoresis precipitin bands suggest the heterogeneity of ferritin in serum from different patients.

On the interfibrillar matrix of the pseudo-exfoliation material

Lenses with pseudo-exfoliation (PE) were suspended in a 10% solution of ferritin. In order to retain ferritin at the surface of the PE material during the preparation for the subsequent transmission electron microscopy, some of the lenses were coated with a thin layer of gelatin before the application of the ferritin solution. It was found that ferritin particles to a certain extent penetrated into the PE material. But the concentration of ferritin was much higher in the gelatin coating than in the PE material. The concentration changed stepwise at the interface between the gelatin and the PE material. The ferritin particles in the PE material were mainly found adjacent to the PE fibrils, and there was a certain tendency towards a linear arrangement of the particles. In some specimens, in which thin filaments were found in the interfibrillar space, the ferritin was found mainly along these filaments. The results are interpreted in light of earlier works in which other tracers have been applied. The marked lower concentration of ferritin in the PE material than in the gelatin coating, and the stepwise fall in concentration at the interface between the two materials, seem to confirm the presence of an interfibrillar matrix of the PE material.

Studies on the rat liver following iron overload. 1. Fine structural appearance

Iron overload of the rat liver following parenteral administration of Jectofer (an iron sorbitol citric acid complex) was studied in the electron microscope. Abundant ferritin-like granules were present in parenchymal and Kupffer cells, partly free in the cell sap and partly concentrated in 3 types of membrane-bound organelles, with characteristic appearances. In the parenchymal cells these organelles consisted of lysosome-like structures, apparent autophagic vacuoles, and vacuoles lacking features linking them to specific cytoplasmic elements. Organelle-bound ferritinlike granules in the Kupffer cells were demonstrated in lysosomelike structures, in phagocytic vacuoles, and in tubular and vacuolar elements referred to as "type 1" and "type 2" bodies. No ferritin-like granules were observed in other cell types than parenchymal and Kupffer cells.

Ceruminous gland adenocarcinoma: a light and electron microscopic study

Tumors of ceruminous gland origin in the external auditory canal are rare in man. A case is described in which such a tumor presented as an invasive vascular temporal bone neoplasm, mimicking a glomus jugulare tumor. Light and electron microscopic study of this tumor confirmed a diagnosis of ceruminous gland adenocarcinoma. Tumors of ceruminous gland origin appear to have a distinctive clinical behavior by virtue of their unique anatomical location in the external auditory canal. Our experience with this case establishes another clinical picture characterizing the histologic type of ceruminoma designated as a ceruminous gland adenocarcinoma. We feel that the generic term "ceruminoma," with its implied histologic subgroups, is useful to the clinician when he encounters a tumor arising from the modified sweat glands of the external auditory canal.

Hemosiderin. an EPR study of water-insoluble iron in human and rat liver

EPR spectra of the water-insoluble iron fraction, hemosiderin of human and rat liver are described. The homogenate of freshly prepared perfused rat liver shows a non-heme iron signal at g=4.3 and a high-spin heme-iron signal around g=6, whereas the washed and sonicated sample of the insoluble iron fraction shows solely a non-heme iron signal at g=4.3. This indicates that hemosiderin from rat liver does not contain heme iron. Human-liver preparations from post mortem obtained material show in the homogenates as well as in the washed and sonicated samples an intense high-spin heme iron signal at g=6.0 and a non-heme iron signal at g=4.3. A comparative experiment, carried out with "aged" rat liver preparations, reveals the same spectra as with the human preparations. It is concluded that that the heme present in the insoluble iron fraction is caused by degradation of hemoglobin in the obduction material, and that heme is not a constituent of the insoluble depot iron.

Investigations of black bronchoalveolar human lavage fluid

The removal by bronchoalveolar lavage (two occasions) of 10(11) black macrophages containing crystals of aluminum silicate, large amounts of amorphous carbon, and oxidized lipids was followed by considerable improvement in gas exchange in a patient. Sixty-eight percent of these pulmonary macrophages were viable and normal, as judged by chemotatctic and phagocytic activity. Except for cigarettes, no source for the previously mentioned ingested foreign substances was found. These observations suggest that removal by lavage of nonviable macrophages laden with foreign bodies from distal portions of the lungs of pulmonary patients may be therapeutically useful.

Ferritin phenotypes: structure and metabolism

Recent advances in our understanding of the biochemistry of ferritin have provided new insights into its role in iron metabolism. Findings of multiple structural forms in many tissues may have important consequences for ferritin's function and metabolism. This article reviews the molecular basis of apoferritin heterogeneity and discusses mechanisms operating in the phenotypic expression of ferritin in normal and malignant cells.

Normal serum ferritin concentrations in precirrhotic hemochromatosis

We investigated 33 of 58 members of two families with latent or precirrhotic hemochromatosis to determine its pattern of inheritance and to evaluate the serum ferritin levels as an index of iron stores. In both families, the pattern of inheritance was as an autosomal dominant trait with incomplete expressivity. Mean serum ferritin values in the affected family members were 88.5 ng per milliliter (range, 28.0 to 201.9) for males and 65.2 ng per milliter (range 23.7 to 97.0) for females, which were no different from controls (P is less than 0.5). Furthermore, the serum ferritin values did not correlate with or reflect mobilizable iron stores, and there were no relations between the serum iron, iron-binding capacity and transferrin saturation (P is less than 0.2). Thus, serum ferritin concentrations in precirrhotic familial hemochromatosis appear to underestimate iron stores. Serum ferritin levels do not help to identify such patients with increased iron stores for therapeutic phlebotomy.

Immunoradiometric assay for ferritin in human serum

A sensitive, specific and precise immunoradiometric assay for ferritin has been developed. Ferritin was measured in the serum of 160 hospital controls, 101 females (118 +/- 9 mug/l) and 59 males (189 +/- 16 mug/l). This difference was statistically significant. In 28 patients with untreated iron deficiency anaemia, serum ferritin concentration (6.1 +/- 0.7 mug/l) was significantly lower than in the controls, but it was within the normal range in 14 cases of polycythaemia vera treated by repeated phlebotomy. In 4 patients with primary haemachromatosis (2884 +/- 56 mug/l), 25 with secondary iron overload states (5702 +/- 1235 mug/l) and 8 with haemolytic anaemia (1612 +/- 605 mug/l), serum ferritin levels were markedly elevated. In 14 cases of transfusional siderosis there was a highly significant correlation between serum ferritin concentration and units of blood transfused. A circadian rhythm in serum ferritin concentration was observed in 7 healthy subjects.

Human isoferritins: organ specific iron and apoferritin distribution

Ferritins from human liver, spleen, heart, pancreas and kidney were compared by electrophoresis and isoelectric focusing in polyacrylamide gels, by immunodiffusion against antisera to homologous and heterologous ferritin, and in some cases by their cyanogen bromide peptides. All ferritins appeared to consist of a single species on gel electrophoresis with the exception of heart ferritin which separated into two major components. Small differences in electrophoretic mobility were found in all tissue ferritins. By contrast, all tissue ferritins were found to consist of multiple forms when analysed by gel electrofocusing. At least five isoferritins were found in most tissues, several of which were common to most tissues. At least two were common to all tissues. Those ferritins which were most easily distinguishable electrophoretically, e.g. spleen and heart ferritin, showed the greatest differences on gel electrofocusing. The ferritin profile was characteristic of each organ and was reproducible both within individuals and between individual tissues. There were striking differences in the iron content of the various isoferritins within a tissue. Further, the iron content of isoferritins common to more than one tissue varied with the tissue of origin. Some isoferritins in several organs and all of the isoferritins in pancreas appeared to contain little, if any, iron. All five tissue ferritins contained antigenic determinants in common with liver ferritin. However, an additional antigenic determinant was found in liver ferritin which was not detectable in the ferritins from the other organs.