Extensive Iron Deposition Research Articles

Brain Iron Accumulation and the Formation of Calcifications After Developmental Zika Virus Infection.

Intracranial calcifications (ICC) are the most common neuropathological finding in the brains of children exposed in utero to the Zika virus (ZIKV). Using a mouse model of developmental ZIKV infection, we reported widespread calcifications in the brains of susceptible mice that correlated in multiple ways with the behavioral deficits observed. Here, we examined the time course of ICC development and the role of iron deposition in this process, in 3 genetically distinct inbred strains of mice. Brain iron deposits were evident by Perls' staining at 2 weeks post infection, becoming increasingly dense and coinciding with calcium buildup and the formation of ICCs. A regional analysis of the brains of susceptible mice (C57BL/6J and 129S1/SvImJ strains) revealed the presence of iron initially in regions containing many ZIKV-immunoreactive cells, but then spreading to regions containing few infected cells, most notably the thalamus and the fasciculus retroflexus. Microglial activation was widespread initially and later delineated the sites of ICC formation. Behavioral tests conducted at 5-6 weeks of age revealed greater deficits in mice with the most extensive iron deposition and calcification of subcortical regions, such as thalamus. These findings point to iron deposition as a key factor in the development of ICCs after developmental ZIKV infection.

Late-Onset Mitochondrial Membrane Protein-Associated Neurodegeneration With Extensive Brain Iron Deposition.

Late-Onset Mitochondrial Membrane Protein-Associated Neurodegeneration With Extensive Brain Iron Deposition.

Extraordinary Hyperbilirubinemia in a Patient With Multiple Myeloma

Multiple myeloma (MM) is a hematologic malignancy that classically manifests with hypercalcemia, renal insufficiency, anemia, and bone disease. Liver dysfunction is a less known complication that usually occurs through liver infiltration by plasma cells, amyloid deposition, or iron deposition. We present a case of a 49 year old Female patient with MM and extreme hyperbilirubinemia. This was a 49 year old female who presented to the emergency room with profound fatigue, progressive jaundice, and pruritus. She had a history of relapsed refractory stage III MM that was being treated with bendamustine. The patient was transfusion dependent, requiring blood transfusions twice a week. Vital signs revealed tachycardia. Her physical exam was remarkable for dry mucous membranes, jaundice, scleral icterus, diffuse abdominal tenderness, and hepatosplenomegaly. Labs were significant for a Hgb of 10 g/dL, platelets of 40,000/mL, total bilirubin of 49.5 mg/dL, direct bilirubin of 30 mg/dL, AST of 18 U/L, ALT of 51 U/L, alkaline phosphatase of 80 U/L, albumin of 3.8 g/dL, INR of 1.3, ferritin of 15,000, and iron of 206. Further work-up, including a hepatitis panel, autoimmune workup, hemolytic workup, toxicology screen, US, MRCP, etc., did not yield a diagnosis.. Transjugular hepatic biopsy was performed to assess the etiology of the hyperbilirubinemia. It showed infiltration of plasma cells, extensive iron deposition in hepatocytes, and Kupffer cells with pericellular fibrosis in the areas infiltrated by plasma cells (figures 1, 2). The patient's liver dysfunction was attributed to secondary hemochromatosis and malignant infiltration of MM. The patient was treated with supportive care. Given her poor prognosis, goals of care were discussed, and she was eventually discharged with home hospice. It is important to recognize liver dysfunction in patients with Multiple Myeloma. Up to 40% of individuals with multiple myeloma have some plasma cell infiltration of the liver. Involvement of the liver in MM carries a poor prognosis. The literature search found that the total bilirubin usually ranges from 3.2 to 17.3 mg/dL in these cases. Our case demonstrated a staggering total bilirubin of 49.5mg/dL. This was multifactorial due to plasma cell infiltration of the liver and secondary hemochromatosis from numerous transfusions. It is important to keep in mind that Bendamustine has also been documented to cause an unconjugated hyperbilirubinemia secondary to hemolytic anemia.2257_A Figure 1. Medium power photomicrograph of a transjuglar liver biopsy with hemosiderin-laden hepatocytes and sinusoidal plasma cell infiltrate with associated fibrosis.2257_B Figure 2. Strong expression of kappa IgG by infiltrating cells.

Ceruloplasmin and hephaestin jointly protect the exocrine pancreas against oxidative damage by facilitating iron efflux

Little is known about the iron efflux from the pancreas, but it is likely that multicopper ferroxidases (MCFs) are involved in this process. We thus used hephaestin (Heph) and ceruloplasmin (Cp) single-knockout mice and Heph/Cp double-knockout mice to investigate the roles of MCFs in pancreatic iron homeostasis. We found that both HEPH and CP were expressed in the mouse pancreas, and that ablation of either MCF had limited effect on the pancreatic iron levels. However, ablation of both MCFs together led to extensive pancreatic iron deposition and severe oxidative damage. Perls’ Prussian blue staining revealed that this iron deposition was predominantly in the exocrine pancreas, while the islets were spared. Consistent with these results, plasma lipase and trypsin were elevated in Heph/Cp knockout mice, indicating damage to the exocrine pancreas, while insulin secretion was not affected. These data indicate that HEPH and CP play mutually compensatory roles in facilitating iron efflux from the exocrine pancreas, and show that MCFs are able to protect the pancreas against iron-induced oxidative damage.

On the R2⁎ relaxometry in complex multi-peak multi-Echo chemical shift-based water-fat quantification: Applications to the neuromuscular diseases

PurposeInvestigation of the feasibility of the R2⁎ mapping techniques by using latest theoretical models corrected for confounding factors and optimized for signal to noise ratio. Theory and methodsThe improvement of the performance of state of the art magnetic resonance imaging (MRI) relaxometry algorithms is challenging because of a non-negligible bias and still unresolved numerical instabilities. Here, R2⁎ mapping reconstructions, including complex fitting with multi-spectral fat-correction by using single-decay and double-decay formulation, are deeply studied in order to investigate and identify optimal configuration parameters and minimize the occurrence of numerical artifacts. The effects of echo number, echo spacing, and fat/water relaxation model type are evaluated through both simulated and in-vivo data. We also explore the stability and feasibility of the fat/water relaxation model by analyzing the impact of high percentage of fat infiltrations and local transverse relaxation differences among biological species. ResultsThe main limits of the MRI relaxometry are the presence of bias and the occurrence of artifacts, which significantly affect its accuracy. Chemical-shift complex R2⁎-correct single-decay reconstructions exhibit a large bias in presence of a significant difference in the relaxation rates of fat and water and with fat concentration larger than 30%. We find that for fat-dominated tissues or in patients affected by extensive iron deposition, MRI reconstructions accounting for multi-exponential relaxation time provide accurate R2⁎ measurements and are less prone to numerical artifacts. ConclusionsComplex fitting and fat-correction with multi-exponential decay formulation outperforms the conventional single-decay approximation in various diagnostic scenarios. Although it still lacks of numerical stability, which requires model enhancement and support from spectroscopy, it offers promising perspectives for the development of relaxometry as a reliable tool to improve tissue characterization and monitoring of neuromuscular disorders.

Voxel-based analysis in neuroferritinopathy expands the phenotype and determines radiological correlates of disease severity

Neuroferritinopathy is an autosomal dominant adult-onset movement disorder which occurs due to mutations in the ferritin light chain gene (FTL). Extensive iron deposition and cavitation are observed post-mortem in the basal ganglia, but whether more widespread pathological changes occur, and whether they correlate with disease severity is unknown. 3D-T1w and quantitative T2 whole brain MRI scans were performed in 10 clinically symptomatic patients with the 460InsA FTL mutation and 10 age-matched controls. Voxel-based morphometry (VBM) and voxel-based relaxometry (VBR) were subsequently performed. Clinical assessment using the Unified Dystonia Rating Scale (UDRS) and Unified Huntington's Disease Rating Scale (UHDRS) was undertaken in all patients. VBM detected significant tissue changes within the substantia nigra, midbrain and dentate together with significant cerebellar atrophy in patients (FWE, p < 0.05). Iron deposition in the caudate head and cavitation in the lateral globus pallidus correlated with UDRS score (p < 0.001). There were no differences between groups with VBR. Our data show that progressive iron accumulation in the caudate nucleus, and cavitation of the globus pallidus correlate with disease severity in neuroferritinopathy. We also confirm sub-clinical cerebellar atrophy as a feature of the disease. We suggest that VBM is an effective technique to detect regions of iron deposition and cavitation, with potential wider utility to determine radiological markers of disease severity for all NBIA disorders.

Lack of Cardiac Iron in SCD Patients Despite Severe Iron Overload

In sickle cell disease (SCD), transfusions improve blood flow by reducing the proportion of red cells capable of forming sickle hemoglobin polymer. The major and unavoidable complication of transfusions in SCD is iron overload. Patients with significant transfusion load and iron siderosis, often have iron deposit into multi organs, including liver, pancreas and heart. However, patients with SCD may be relatively protected from iron mediated cardiac toxicity as compared to patients with thalassemia and similar transfusion load. Nonetheless while patients with SCD have less iron deposition in the heart it is presumed that severe loading will eventually lead to cardiac involvement. We report here two patients with scd with severe iron overload who had no cardiac involvement.These are an 18 year old female and her 20 year old male sibling, known to have SCD (HbSS) with significant blood transfusions history, once a month or every two weeks for 12 years duration. Both had undergone splenectomy, and multiple hospitalizations for pain crises and acute chest syndrome. They had received intermittent iron chelation therapy for only 2 years. Examination revealed marked hepatomegaly and highly elevated ferritin levels, 11964ng/ml and 7098ng/ml respectively, suggestive of iron overload. Both patients had unremarkable electrocardiogram and echocardiogram. SGPT and SGOT are normal. Both patients are below the 5thpercentile for height, and l the 18 year old girl is pre-pubertal, has growth hormone deficiency and is on treatment.Cardiac, liver and pancreas magnetic resonance imaging with T2* showed normal cardiac structure and function without siderosis ( heart T2*32 ms and 35 ms in the female and male siblings, respectively [normal >20 ms]). There was however considerable liver siderosis with estimated liver iron content 16.6±4.4 mg/g dry weight (female sibling) and 13.9±1.8 mg/g dry weight (male sibling). The corresponding R2* were 646±165 HZ and 541±62 Hz, respectively. Also, there was mild to moderate pancreatic siderosis in the 18 year old female (R2* 111 HZ) and mild pancreatic siderosis in her sibling (R2* 55 Hz)These two cases while consistent with what has been reported are unusual because of the degree of iron ovreloead. It is an unexepected finding that despite such extensive iron deposits in the liver, there is no evidence of cardiac iron. It thus seems that in patients with sickle cell disease, even with extensive liver siderosis and endocrine dysfunction there is sparing of the heart. Collecting and studying such cases may shed light on the mecahins of cardiac protection from iron overload in sickle cell disease. DisclosuresNo relevant conflicts of interest to declare.

In-vivo detection of inflammation and neurodegeneration in the chronic phase after permanent embolic stroke in rats

Neuroinflammation with microglia activation (MA) constitutes a key tissue response in acute stroke. Until now, its course in the chronic stage is less well defined. Here, we investigated (i) neuroinflammation in the chronic stage of a rat model of embolic stroke (n=6), and (ii) whether this process can be visualized in vivo by multimodal imaging using Magnetic Resonance Imaging (MRI) and Positron-Emission-Tomography (PET). Imaging data were verified using histology and immunohistochemistry. Repetitive PET studies until week 6 after stroke reveal poststroke inflammation as a dynamic process that involved the infarct, the surrounding tissue and secondary degenerating areas in a complex fashion. At the end, 7 months after stroke, neuroinflammation had almost completely vanished at the lesion side. In contrast, remote from the primarily infarcted areas, a marked T2⁎- hypointensity was detected in the ipsilateral thalamus. In the corresponding area, [11C]PK11195-PET detected microglia activation. Immunohistochemistry confirmed activated microglia in the ipsilateral thalamus with signs of extensive phagocytosis and iron deposition around plaque-like amyloid deposition. Neuronal staining (NeuN) revealed pronounced neuronal loss as an endpoint of neurodegeneration in these areas.In conclusion, the data demonstrate not only ongoing thalamic neuroinflammation but also marked neurodegeneration remote from the lesion site in the chronic phase after stroke in rats. Both, neuroinflammation and neurodegeneration were accessible to (immuno-) histochemical methods as well as to in vivo methods using [11C]PK11195-PET and T2⁎-weighted MRI. Although the functional roles of these dynamic processes remain to be elucidated, ongoing destruction of neuronal tissue is conceivable. Its inhibition using anti-inflammatory substances may be beneficial in chronic post-stroke conditions, while multimodal imaging can be used to evaluate putative therapeutic effects in vivo.

In Vivo Transfer of Superparamagnetic Iron Contrast Agent Ferucarbotran in Transplanted Rat Pancreatic Islets

Introduction: Labeling of isolated pancreatic islets with superparamagnetic iron oxide (SPIO) nanoparticles enables their post-transplant monitoring by magnetic resonance imaging (MRI) for up to six months after transplantation. Although the nanoparticles are incorporated into all major islet cell types during in vitro culture, little is known about their fate in vivo. We studied the morphology of labeled islets after transplantation aiming to identify the MRI contrast particles and their relationship to transplantation outcomes. Methods: Rat islets (Lewis rats) labeled with the SPIO contrast agent ferucarbotran were transplanted via portal vein into the liver or under the kidney capsule of syngeneic and allogeneic rats (Brown Norway rats). After in vivo MRI, morphology of the transplanted tissue was studied by light, fluorescence and transmission electron microscopy at different time points for up to three months. Results: Morphology of syngeneic islets transplanted beneath the kidney capsule versus into the liver was similar. Iron particles were almost completely eliminated from the endocrine cells and located in hostderived macrophages surrounding the vital islets; the particles persisted at the transplantation site for the entire study period. In the allogeneic model, islets lost their function and were completely rejected within nine days following transplantation in both transplant models. However, intercellular transport of the SPIO particles and subsequent MRI findings were different in the liver and kidney. In the liver the decreasing number of islet-related MRI spots corresponded with clearance of iron particles in rejected islets; in contrast, with renal transplants extensive iron deposits with a high effect on MRI signal persisted in phagocytic cells beneath the renal capsule for up to two months. Conclusions: Although the SPIO particles were located aside the endocrine cells after islet transplantation, MRI detection of the contrast agent correlated with islet survival and function in islet transplantation into the liver. However, it did not correlate in the case of transplantation beneath the renal capsule.[Figure]Magnetic resonance and histochemical imaging of SPIO labeled islet allografts 14 day after transplantation. A) Transplantation beneath the renal capsule: Despite complete islet rejection, SPIO particles remained in situ and were easily detected by MRI. B) Transplantation into the portal vein: Islets were completely rejected and only little iron was present in surrounding macrophages. Almost none islet-related positive signals were detected on MR scan. Arowhead - hypointense signal of SPIO contrast agent, arrows - SPIO particles detected by Pearl's reaction. Supported by grant MZO 00023001.

Processing of superparamagnetic iron contrast agent ferucarbotran in transplanted pancreatic islets

Labeling of pancreatic islets with superparamagnetic iron oxide (SPIO) nanoparticles enables their post-transplant monitoring by magnetic resonance imaging (MRI). Although the nanoparticles are incorporated into islet cells in culture, little is known about their fate in vivo. We studied the morphology of labeled islets after transplantation, aiming to identify the MRI contrast particles and their relationship to transplantation outcomes. Rat islets labeled with the ferucarbotran were transplanted into the liver or under the kidney capsule of syngeneic and allogeneic rats. After in vivo MRI, morphology was studied by light, fluorescence and transmission electron microscopy. Morphology of syngeneic islets transplanted beneath the kidney capsule vs into the liver was similar. Iron particles were almost completely eliminated from the endocrine cells and remained located in host-derived macrophages surrounding the vital islets for the entire study period. In the allogeneic model, islets lost their function and were completely rejected within nine days following transplantation in both transplant models. However, intercellular transport of the SPIO particles and subsequent MRI findings was different in the liver and kidney. In the liver, the decreasing number of islet-related MRI spots corresponded with clearance of iron particles in rejected islets; in contrast, with renal transplants extensive iron deposits with a high effect on MRI signal persisted in phagocytic cells beneath the capsule. We conclude that MRI detection of the iron contrast agent correlates with islet survival and function in islet transplantation into the liver, while it does not correlate in the case of transplantation beneath the renal capsule.

Myocyte Damage and Loss of Myofibers is the Potential Mechanism of Iron Overload Toxicity in Congestive Cardiac Failure in Thalassemia. Complete Reversal of the Cardiomyopathy and Normalization of Iron Load by Deferiprone

Cardiac damage caused by iron overload toxicity is the main cause of death in thalassemia patients. Biopsy samples of poorly chelated thalassemia patients who suffered congestive cardiac failure (CCF) show extensive iron deposition in the myocardium. In one patient who survived CCF, a cardiac biopsy was performed during the removal of a thrombus caused by a port-a-cath, which was used for the administration of intravenous (iv) deferoxamine (DFO). Ultrastructural pathology studies of the cardiac biopsy indicated extensive iron deposition in myocytes with accumulation of iron mainly in lysosomes, leading in some cases to their disruption. Damage to other intracellular components of the myocytes and loss of myofibers was also observed. The patient became intolerant to iv and subcutaneous (sc) DFO 2 years after the CCF, and was then treated with deferiprone (L1) for 7 years. Within 1 year of L1 treatment at 75–80 mg/kg/day, serum ferritin levels were reduced to <0.45 mg/L and she became asymptomatic, needing no further drugs for her cardiomyopathy. Lowering the L1 dose to 50–70 mg/kg/day caused an increase in serum ferritin levels. Maintenance of normal iron stores during the last 3 years as detected by cardiac and liver magnetic resonance imaging (MRI) T2 and T2* and normalization of serum ferritin levels (<0.15 mg/L) was observed following L1 therapy at 80–85 mg/kg/day. Deferiprone (>80 mg/kg/day) appears to be effective in the rapid clearance of cardiac iron, in the reversal of iron overload related cardiomyopathy, in the maintenance of normal iron stores and the overall long-term survival of thalassemia patients.

A Case of Neonatal Hemochromatosis‐Like Liver Failure with Spontaneous Remission

A Case of Neonatal Hemochromatosis‐Like Liver Failure with Spontaneous Remission

Abnormalities in bone mineral density and bone histology in thalassemia.

This study demonstrated that there was extensive iron staining on trabecular surface and marked reduction in trabecular bone volume without significant alteration in bone formation and bone resorption rates as well as significant reduction in bone mineral density in 18 thalassemic patients. Serum IGF-I was reduced and may modulate the reduction of bone mass. Bone histomorphometric studies in thalassemia to show alterations in bone histology and their relationship to biochemical parameters are very limited. Therefore, this study was systematically conducted to determine the alterations in thalassemia patients. Serum biochemical parameters, trans-iliac crest bone biopsy, and determination of bone mineral density of femur and lumbar spine were done in 18 thalassemic patients (10 females and 8 males). Serum osteocalcin, carboxy terminal teleopeptide fragment of type I collagen, and parathyroid hormone levels were within normal limits, but serum 25(OH) vitamin D (19.3 +/- 1.6 ng/ml) and 1,25(OH)2 vitamin D (33.77 +/- 1.51 pg/ml) levels were decreased. Serum insulin-like growth factor I (IGF-I; 145.2 +/- 20 ng/ml) was suppressed, whereas serum ferritin (1366.6 +/- 253.9 ng/ml) was markedly elevated. Reduced bone mineral density was found in all studied areas. Trabecular bone volume was significantly decreased (16.65 +/- 1.12%), whereas bone formation rate, eroded surface, and other bone histomorphometric parameters were within normal limits. The trabecular bone volume varied significantly with bone mineral density of total femur (r = 0.48, p = 0.04). There was an extensive stainable iron surface on the mineral front (9-60%). Significant correlation between serum IGF-I, serum ferritin, stainable iron surface, and bone mineral density, lumbar spine, and total femur were found. Serum IGF-I correlated with trabecular bone volume (r = 0.6, p = 0.03), inversely with both serum ferritin level (r = -0.6, p < 0.01), and inversely with stainable iron surface (r = -0.53, p = 0.02). Multiple regression analysis demonstrated that IGF-I was the only independent variable that determined bone mineral density of lumbar spine and total femur. Low bone mineral density and reduced trabecular bone volume with extensive iron deposition are the predominant findings in thalassemic patients. There was no evidence of increased bone resorption or mineralization defect. A reduction in circulatory IGF-I may modulate the reduction of bone mass.

Iron deposition in skin of patients with haemochromatosis

Haemochromatosis is the most common inherited liver disease in Caucasians and the most common autosomal recessive genetic disorder. It is characterized by inappropriately high iron absorption resulting in progressive iron overload in parenchymal organs such as liver, heart, pancreas, pituitary, joints, and skin. Upon early detection, haemochromatosis can be a manageable chronic disease but, if undetected, is potentially fatal. Skin biopsies were obtained from patients and from healthy donors. Images of the elemental distributions in skin were obtained using nuclear microscopy techniques (nuclear microprobe, NMP). Elemental profiles along skin, and intra-, and extra-cellular iron concentrations, were determined. Results for patients with haemochromatosis were cross-examined with morphologic features and with data obtained for healthy skin. Skin iron content is much increased in patients with haemochromatosis when compared with healthy subjects. Extensive iron deposits are observed at dermis, at the dermo-epidermal interface, at upper epidermis layers and at stratum corneum. Iron deposition was observed preferentially at cell boundaries or at the interstitial matrix.

Downeast Anemia (dea), a New Mouse Model of Severe Nonspherocytic Hemolytic Anemia Caused by Hexokinase (HKI) Deficiency

ABSTRACTA new spontaneous mutation in the A/J inbred mouse strain, downeast anemia (dea), causes severe hemolytic anemia with extensive tissue iron deposition and marked reticulocytosis. The anemia is present at birth and persists throughout life. The defect is inherited as an autosomal recessive and is transferable through bone marrow stem cells. The red cell morphology is consistent with a nonspherocytic hemolytic anemia, suggestive of a red cell enzymopathy. In linkage analysis, dea is nonrecombinant with the hexokinase-1 gene (Hk1) on mouse Chromosome 10. Expression of Hk1 is markedly decreased in dea erythroid tissues, and the transcript produced is larger than normal. Hexokinase enzyme activity is significantly decreased in dea tissues, including red cells, spleen, and kidney. Southern blot analyses revealed ∼5.5 kb of additional sequence in the 5′ portion of the dea Hk1 gene, which was identified by direct sequencing as an early transposon (ETn) insertion in intron 4. ETn insertions disrupt genes in several mouse models by a variety of mechanisms, including aberrant splicing of ETn sequences into the mRNA. We conclude that the primary gene defect in the dea mutation is in Hk1 and that dea is a model of generalized hexokinase deficiency, the first such model identified to date.

Hemochromatosis as a Risk Factor for Fulminant Staphylococcus aureus Pneumonia*

Hemochromatosis as a Risk Factor for Fulminant Staphylococcus aureus Pneumonia*

Spur cell anaemia and hepatic iron stores in patients with alcoholic liver disease undergoing orthotopic liver transplantation

BACKGROUNDFollowing orthotopic liver transplantation (OLT) histological examination of explant livers from patients with alcoholic liver disease (ALD) sometimes shows extensive iron deposits in a distribution suggestive of homozygous haemochromatosis.AIMSTo use...

Ceruloplasmin Ferroxidase Activity Stimulates Cellular Iron Uptake by a Trivalent Cation-specific Transport Mechanism

The balance required to maintain appropriate cellular and tissue iron levels has led to the evolution of multiple mechanisms to precisely regulate iron uptake from transferrin and low molecular weight iron chelates. A role for ceruloplasmin (Cp) in vertebrate iron metabolism is suggested by its potent ferroxidase activity catalyzing conversion of Fe2+ to Fe3+, by identification of yeast copper oxidases homologous to Cp that facilitate high affinity iron uptake, and by studies of "aceruloplasminemic" patients who have extensive iron deposits in multiple tissues. We have recently shown that Cp increases iron uptake by cultured HepG2 cells. In this report, we investigated the mechanism by which Cp stimulates cellular iron uptake. Cp stimulated the rate of non-transferrin 55Fe uptake by iron-deficient K562 cells by 2-3-fold, using a transferrin receptor-independent pathway. Induction of Cp-stimulated iron uptake by iron deficiency was blocked by actinomycin D and cycloheximide, consistent with a transcriptionally induced or regulated transporter. Cp-stimulated iron uptake was completely blocked by unlabeled Fe3+ and by other trivalent cations including Al3+, Ga3+, and Cr3+, but not by divalent cations. These results indicate that Cp utilizes a trivalent cation-specific transporter. Cp ferroxidase activity was required for iron uptake as shown by the ineffectiveness of two ferroxidase-deficient Cp preparations, copper-deficient Cp and thiomolybdate-treated Cp. We propose a model in which iron reduction and subsequent re-oxidation by Cp are essential for an iron uptake pathway with high ion specificity.

Diabetic Peripheral Neuropathy: Possible Involvement of Iron Bound to Glycated Basement Membrane Proteins † 470

The etiology of peripheral nerve and vascular dysfunction in insulin-dependent diabetes mellitus is unknown, but experimental evidence indicates that defects in nitric oxide-mediated, endothelium-dependent vascular relaxation lead to diminished neuronal blood flow. We hypothesize that these peripheral nerve and vascular abnormalities arise from an accumulation of sub-endothelial iron - bound to glycated proteins of the internal elastic lamina - which effects the catalytic decomposition of nitric oxide. In support of this hypothesis: (1) The administration of iron chelators such as desferrioxamine and trientine fully corrects defective endothelium-dependent relaxation and nerve conduction velocity in diabetic rats (J. Clin. Invest. 96:1159, 1995). (2) Glycated bovine elastin and soluble collagen fragments (gelatin) bind iron (added as ferrous ammonium sulfate). Maximal bound iron ranges from 10-15 μmol/g glycated protein vs.<0.3 μmol/g non-glycated protein. (3) In preliminary studies, tissue sections from the area of the sciatic nerve in rats following 2 months of streptozotocin-induced diabetes were stained for iron (with a sensitive silver-based reaction). In many cases, extensive iron deposition was observed in the internal elastic laminae of large and small arteries of diabetic - but not control - animals. These findings support the hypothesis that, in diabetes, extensive glycation of basement membrane/internal elastic lamina proteins generates adducts capable of binding adventitious iron. The resultant subendothelial `glycochelates' catalytically destroy endothelium-derived nitric oxide, thereby contributing to an imbalance of vasodilator vs. vasoconstrictor factors and resulting in a state of relative chronic vasoconstriction. The diminished blood flow to peripheral nerves leads to neuronal hypoxia and eventual nerve death. If true, this provides a rationale for the administration of iron chelators for the prevention or even reversal of the peripheral vasculopathy and neuropathy of diabetes.

Spur cell anemia and hepatic iron stores in patients with alcoholic liver disease undergoing orthotopic liver transplantation

Following orthotopic liver transplantation (OLT) histological examination of explant livers from patients with alcoholic liver disease (ALD) sometimes shows extensive iron deposits in a distribution suggestive of homozygous haemochromatosis.To use haemochromatosis gene (HFE) assays to distinguish between ALD with notable siderosis and hereditary haemochromatosis. To evaluate the possible influence of spur cell haemolytic anaemia on hepatic iron loading.Thirty seven patients with ALD were abstinent for at least six months prior to OLT. Twenty three patients had transferrin saturations greater than 55%, 16 also had increased serum ferritin (>350 micrograms/l). Eight of 37 (22%) explant livers had grade 3 or 4 hepatic iron deposition, predominantly in hepatocytes. Of these, four had a hepatic iron index greater than 1. 9 and most seemed to have spur cell haemolytic anaemia.Mutation analysis for C282Y and H63D mutations was performed on DNA extracts from peripheral blood or explant liver. Spur cell haemolytic anaemia was diagnosed when the haemoglobin was 105 g/l in the presence of notable acanthocytosis.None of the eight patients with grade 3 or 4 hepatic iron had evidence of the C282Y mutation. Two of the eight were heterozygous for H63D. None of the remaining 28 patients tested showed homozygous HFE mutations. Spur cell anaemia was present in six of the eight patients with heavy iron deposition and only one of the remaining patients.The HFE mutation was not present in these patients with advanced ALD and heavy iron loading. Spur cell haemolytic anaemia provides an alternative potential mechanism for the heavy iron loading.