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PubMed1999

Dose-dependent increase of oxidative damage in the testes of rats subjected to acute iron overload.

This study describes the in vivo response of rat testes to acute iron overload. Male Wistar rats (250-300 g) were injected ip with iron dextran at doses of 250 (Fe250), 500 (Fe500), or 1000 mg/kg body wt (Fe1000) or with saline (C). Parameters of oxidative stress and iron toxicity were measured 20 h after injection. Total iron content was 3.5-, 5.3-, and 10.4-fold higher in the Fe250, Fe500, and Fe1000 groups, respectively, compared to controls (320 +/- 22 nmol/g tissue). Histological studies showed that: (a) iron accumulated in the sperm and other testes cells, and (b) spermatogenesis was markedly lower in the Fe1000 group. The concentration of alpha-tocopherol, ubiquinol-9, and ubiquinol-10 in the testes was inversely correlated with the extent of oxidation. Testes chemiluminescence was 45% higher in the Fe1000 group compared to controls (41 cps/cm(2)). Endogenous levels of lipid oxidation, evaluated as 2-thiobarbituric acid-reactive substances, were 46, 73, and 82% higher in the groups Fe250, Fe500, and Fe1000, respectively, than in controls (33.6 +/- 1.4 nmol/g tissue). Oxidative damage to DNA evaluated by the presence of 8-oxo-2'-deoxyguanosine (oxo(8)dG), was 26, 39, and 74% higher in the Fe250, Fe500, and Fe1000 groups, respectively, than in the C group (2.3 +/- 0.1 oxo(8)dG/10(5)dG). Protein oxidation was measured as protein thiols and carbonyl content in proteins and glutamine synthase activity. Protein thiols content and glutamine synthase activity were similar in all the groups, while the protein-associated carbonyls content was 96% higher in the Fe1000 group than in the C group (2.1 +/- 0.4 nmol/mg protein). No changes in the activities of superoxide dismutase, catalase, and glutathione peroxidase were observed. The results showed that in vivo iron overload induced oxidative stress and the impairment of spermatogenesis in rat testes that were dependent on the amount of iron supplemented and its accumulation in the tissue.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed1995

Kupffer cell iron overload induces intercellular adhesion molecule-1 expression on hepatocytes in genetic hemochromatosis.

The mechanisms underlying iron-induced liver fibrogenesis in patients with genetic hemochromatosis are poorly understood. We studied signs of Kupffer cell activation and inflammatory responses in liver biopsy specimens obtained from 15 patients with untreated and six patients with treated hemochromatosis. Immunohistochemistry was performed on 11 of the untreated and all treated patients. Three of the untreated patients (20%) had cirrhosis and eight (53%) had fibrosis. None had chronic active hepatitis (CAH). Immunohistochemistry indicated that 55% of the untreated patients had sparse intercellular adhesion molecule-1 (ICAM-1) expression by hepatocytes, and all of these had Kupffer cell iron overload. No ICAM-1 expression was seen by hepatocytes in treated patients or healthy controls. ICAM-1 was strongly expressed by hepatocytes from control patients with inflammatory liver disease. HLA-DR reactivity was seen on sinusoidal cells in all groups, but not on hepatocytes except for two of the control patients with CAH. Twenty-seven percent of the untreated hemochromatosis patients displayed moderate infiltration by CD3-positive lymphocytes. Electron microscopy of samples from untreated hemochromatosis patients showed hypertrophic Kupffer cells containing iron-rich remnants of phagocytosed hepatocytes. Fat-storing cells close to iron-laden hepatocytes contained multiple lipid droplets and adjacent collagen fibril bundles. Thus, in patients with untreated genetic hemochromatosis and Kupffer cell iron overload, hepatocytes occasionally express ICAM-1. In regions with heavy iron overload, Kupffer cell hypertrophy and transition of fat-storing cells are seen. Our findings indicate that release of factors from iron-loaded, activated Kupffer cells is of importance for the transformation of fat-storing cells and increased collagen deposition seen in genetic hemochromatosis.

Adult↗
PubMed2003

Tissue Doppler echocardiography in patients with thalassaemia detects early myocardial dysfunction related to myocardial iron overload.

AIMS: To compare an echocardiographic method for detecting abnormal cardiac function before development of overt cardiomyopathy with a recently validated technique of quantifying myocardial iron load. METHODS AND RESULTS: We examined thalassaemia patients whose myocardial iron load had been evaluated with magnetic resonance imaging (MRI). By tissue Doppler echocardiography, myocardial velocities were sampled continuously from base to apex in the RV and LV free wall, and the septum in 52 patients aged 29.2 (14.2-43.1) years and 52 age-matched controls. Ninety-six percent of patients had normal LV ejection fraction by MRI. Thirty-eight (73%) had abnormal iron loading of the myocardium, and 33 of those had regional wall motion abnormalities detected in the septum (n=29), LV (n=2), RV (n=1), and septum plus LV (n=1). The incidence of wall motion abnormalities was significantly higher (P<0.04) in patients with myocardial iron overload (87%) than in the 14 without (35%). Furthermore, myocardial iron overload was suggested by a low T2(*)(15.1+/-15.8 ms) in patients with wall motion abnormalities vs those with normal wall motion (T2(*): 30+/-19 ms) (P<0.007). CONCLUSIONS: Wall motion abnormalities may represent an early sign of cardiac disease despite preserved global function. The regional abnormalities are related to iron overload and easily detectable with tissue Doppler echocardiography.

Adolescent↗
PubMed2005

Effects of waterborne iron overload and simulated winter conditions on acute physiological stress response of whitefish, Coregonus lavaretus.

Two-year-old whitefish (Coregonus lavaretus) were exposed for 30 days to episodic iron overload in iron-rich humic water (5%) supplemented with inorganic iron (5 mg FeL(-1)). Two parallel laboratory exposures were performed, one under conditions simulating winter and the other under conditions simulating spring. After exposure, some of the fish were subjected to acute handling stress in the form of a short air challenge to reveal possible modification of the primary and secondary stress responses. In whitefish sampled without additional handling, iron accumulated in the liver (under spring conditions) and gills (under winter and spring conditions); plasma catecholamine and beta-estradiol (both winter and spring groups) as well as blood hematocrit (winter group only) levels were depressed; blood glucose (winter group only) and red blood cell (RBC) Na+ levels (spring group only) were increased. In handled whitefish, liver glycogen phosphorylase (GPase), RBC, and blood glucose stress responses were impaired by the applied exposure conditions, which reflected natural iron-rich humic water. Exposure also removed some physiological effects of the applied ambient conditions: plasma catecholamines and beta-estradiol, gill Na+/K+ -ATPase, and RBC K+ concentration were not different in two iron-exposed fish groups, whereas there was a difference in reference fish. Thus, the physiological effects of this type of subchronic exposure, together with alterations in the acute stress response, can lead to incorrect conclusions being drawn from the results, if the effects of time-dependent stress response are ignored. In conclusion, waterborne iron overload may impair the optimal capacity of whitefish to carry out their normal physiological functions such as responding to external threats.

Adaptation, Physiological↗
PubMed2001

Real-time polymerase chain reaction with fluorescent hybridization probes for the detection of prevalent mutations causing common thrombophilic and iron overload phenotypes.

We evaluated more than 450 patients with thrombophilia or iron overload for the presence of a factor V Leiden (R506Q), prothrombin G20210A, or HFE C282Y mutation using a standard method (polymerase chain reaction [PCR]-restriction fragment length polymorphism) and a comparative real-time PCR fluorescent resonance energy transfer (FRET) hybridization probe melting curve method. There was 100% concordance between the genotypes ascertained by the 2 methods (at each loci). In addition, phenotypic biochemical laboratory parameters measured on a subset of referred patients correlated with their respective genotypes. In the iron overload cohort, HFE C282Y homozygotes (n = 74) had significantly higher (P < .0001) transferrin saturation levels (74% +/- 25%) than did nonhomozygotes (n = 340; 51.4% +/- 28%), suggesting a genotype-dependent increase in body iron loads. In the thrombophilic cohort, the degree of activated protein C resistance (APCR), measured by a clotting time-based test, was associated significantly with the presence of 0 (n = 255; APCR = 2.59 +/- 0.26), 1 (n = 84; APCR = 1.61 +/- 0.13), or 2 (n = 5; APCR = 1.16 +/- 0.04) copies of the mutant factor V Leiden allele. As the fluorescent genotyping method required no postamplification manipulation, genotypes could be determined more quickly and with minimized risk of handling errors or amplicon contamination. In addition to these practical advantages, the FRET method is diagnostically accurate and clinically predictive of phenotypic, disease-associated manifestations.

Activated Protein C Resistance↗
PubMedDate not supplied

Intestinal over-expression of iron transporters induces iron overload in birds in captivity.

Hereditary hemochromatosis (HH) is a frequent genetic disease of older subjects of northern European descent. It is characterized by increased iron absorption and severe iron overloading in parenchymal organs. A similar disturbance of iron metabolism occurs in specific animal species in captivity. To address the key features leading to high absorption and thus to iron overload in these animals, we have studied the two iron transport proteins DMT1 and Ireg1 in the best-known susceptible species, the mynah bird. Here, we show that these birds have a high expression of DMT1 in the duodenum and also a strikingly high expression of Ireg1 along the whole small intestine. We believe that the iron accumulation in susceptible species only occurs in captivity because of a genotypic adaptation to their natural environment, where contrary to captivity, dietary iron is hardly available. The Caucasian population carrying mutations leading to iron overload today may have also benefited from the genetic advantage of up-regulating iron transport millennia ago, when dietary iron was scarce.

Amino Acid Sequence↗
PubMed2004

Efficacy and safety of phlebotomy to reduce transfusional iron overload in adult, long-term survivors of acute leukemia.

BACKGROUND: Transfusional iron overload is a frequent finding in long-term survivors of acute leukemia (AL). Only a few studies have reported the results of iron depletion therapy in this category of patients. STUDY DESIGN AND METHODS: Between January 1996 and July 2003, 26 consecutive adult patients who achieved complete remission of AL and developed transfusional iron overload underwent a weekly phlebotomy program at our transfusion center. Serum ferritin levels and transferrin saturation were monitored during the iron depletion therapy and the follow-up period. These AL patients were also checked for the presence of 12 hereditary hemochromatosis (HH) gene mutations. RESULTS: After a mean follow-up of 57.8 months, therapeutic phlebotomy (mean number of units collected, 36.6) was effective in reducing mean ferritin concentration and transferrin saturation from 1726.9 to 93.0 mg per L and from 54.7 to 23.3 percent, respectively. The presence of a HH gene mutation did not influence initial iron status or response to treatment. The phlebotomy program was well tolerated and no adverse events were recorded during or after collection. In three cases the time between phlebotomies was increased because of patient's poor compliance or low Hb levels. CONCLUSION: Our study shows that phlebotomies are a safe and effective method for reducing iron over-load in multiply transfused long-term AL survivors with secondary hemochromatosis.

Adult↗
PubMed1998

Hepatic iron overload in patients with chronic viral hepatitis: role of HFE gene mutations.

Mild to moderate hepatic iron overload is frequent in patients with chronic viral hepatitis (CH). We evaluated the role of hemochromatosis (HFE) gene mutations and other acquired factors in the development of iron overload in these patients. We studied 110 patients with chronic B or C viral hepatitis (31 women, 79 men), including 20 with cirrhosis, and 139 controls. Hepatic iron was evaluated by semiquantitative analysis in all the patients, and hepatic iron concentration (HIC) was determined in 97 of them (26 women, 71 men). C282Y and H63D mutations were sought in all the subjects by a polymerase chain reaction-restriction assay. The frequency of HFE genotypes and alleles did not differ in patients and controls. No relation was detected between hepatic iron stores and HFE gene mutations in women. In men, all C282Y heterozygotes had iron overload, and the H63D mutation was significantly more frequent in patients with more marked hepatic siderosis than in those with mild or no siderosis (P = .0039) and in controls (P = .0008). Heavy alcohol intake and hepatic cirrhosis were also associated with increased hepatic iron stores in the men. In the 71 men in whom HIC was measured, multiple regression analysis showed that this variable was related independently only to alcohol intake and HFE gene mutations. We suggest that in patients with CH, iron accumulates in the liver as the result of an interplay between genetic and acquired factors, and that increased liver iron stores may influence progression toward liver fibrosis.

Adult↗
PubMed2002

[Iron overload and liver diseases].

The awareness of the harm of deficiency in iron, an essential trace elements for the growth of almost all types of biological cells, has long been established. Iron overload, however, is not equally well documented to be related to certain diseases. In this article the author reviews the association of iron overload with some frequent hepatic diseases.

Fatty Liver↗
PubMed1980

Activities of some free-radical scavenging enzymes and glutathione concentrations in human and rat liver and their relationship to the pathogenesis of tissue damage in iron overload.

The activities and subcellular distribution of enzymes implicated in the protection of cells from free-radical mediated damage were determined in liver biopsy specimens from control and iron-overloaded patients. 2. There was a small but insignificant decrease in the activity of glutathione reductase in patients with secondary iron overload due to multiple transfusion therapy for thalassaemia major. 3. The activities of superoxide dismutase, catalase and glutathione peroxidase were similar in both patient groups. 4. Subcellular fractionation studies indicated a major cytosolic localization of these enzymes with a minor mitochondrial component. The relative proportions of the enzymes in the two locations was similar in both control and iron-overloaded patients. 5. Approximately 80% of the hepatic glutathione was present in the reduced form in both patient groups and it is concluded that although free-radical mediated damage might be implicated in the pathogenesis of tissue damage due to iron overload no significant defect in these protective mechanisms can be demonstrated.

Animals↗
PubMed2006

Relationships of serum ferritin, transferrin saturation, and HFE mutations and self-reported diabetes in the Hemochromatosis and Iron Overload Screening (HEIRS) study.

OBJECTIVE: We evaluated the associations of self-reported diabetes with serum ferritin concentration, transferrin saturation (TfSat), and HFE C282Y and H63D mutations in six racial/ethnic groups recruited at five field centers in the Hemochromatosis and Iron Overload Screening (HEIRS) study. RESEARCH DESIGN AND METHODS: Analyses were conducted on 97,470 participants. Participants who reported a previous diagnosis of diabetes and/or hemochromatosis or iron overload were compared with participants who did not report a previous diagnosis. RESULTS: The overall prevalence of diabetes was 13.8%; the highest prevalence was in Pacific Islanders (20.1%). Of all participants with diabetes, 2.0% reported that they also had hemochromatosis or iron overload. The mean serum ferritin concentration was significantly greater in women with diabetes in all racial/ethnic groups and in Native-American men with diabetes than in those without diabetes. The mean serum ferritin concentration was significantly lower in Asian men with diabetes than in those without diabetes. Mean TfSat was lower in participants with diabetes from all racial/ethnic groups except Native-American women than in those without diabetes. There was no significant association of diabetes with HFE genotype. The mean serum ferritin concentration was greater (P < 0.0001) in women with diabetes than in those without diabetes for HFE genotypes except C282Y/C282Y and C282Y/H63D. Log serum ferritin concentration was significantly associated with diabetes in a logistic regression analysis after adjusting for age, sex, racial/ethnic group, HFE genotype, and field center. CONCLUSIONS: Serum ferritin concentration is associated with diabetes, even at levels below those typically associated with hemochromatosis or iron overload.

Adult↗
PubMed2003

Patients with biochemical iron overload: causes and characteristics of a cohort of 150 cases.

Biochemical iron overload (IO) is a frequent metabolic abnormality. It may be caused by several diseases, and data regarding the relative frequency of these are scant. A single diagnostic protocol including clinical, biochemical, and genetic data was used to diagnose the cause of biochemical IO in a group of 150 patients referred by general practitioners. Severe alterations of the HFE gene (42 patients, 28%), hepatitis C virus infection (33 patients, 22%), and dysmetabolic syndrome with iron overload (DSIO) (22 patients, 15%) emerged as the main causes, and other single causes were found in 20 patients (13%). In 19 patients (13%), multiple causes of IO were found, and in 14 patients no cause was found, 5 of whom had classical criteria of genetic hemochromatosis (GH) without HFE mutations. Transferrin saturation index (TSI) had a very low positive predictive value (0.16) for GH among patients with biochemical IO in this setting. In conclusion, 90% of patients with biochemical IO were diagnosed with a specific disorder. GH, hepatitis C infection, and DSIO were the major causes, and a large group of patients had multiple causes of IO. TSI is not a useful indicator of GH in patients referred by general practitioners.

Adult↗
PubMed2000

Transferrin receptor 2: continued expression in mouse liver in the face of iron overload and in hereditary hemochromatosis.

Hereditary hemochromatosis (HH) is a common autosomal recessive disorder characterized by excess absorption of dietary iron and progressive iron deposition in several tissues, particularly liver. Liver disease resulting from iron toxicity is the major cause of death in HH. Hepatic iron loading in HH is progressive despite down-regulation of the classical transferrin receptor (TfR). Recently a human cDNA highly homologous to TfR was identified and reported to encode a protein (TfR2) that binds holotransferrin and mediates uptake of transferrin-bound iron. We independently identified a full-length murine EST encoding the mouse orthologue of the human TfR2. Although homologous to murine TfR in the coding region, the TfR2 transcript does not contain the iron-responsive elements found in the 3' untranslated sequence of TfR mRNA. To determine the potential role for TfR2 in iron uptake by liver, we investigated TfR and TfR2 expression in normal mice and murine models of dietary iron overload (2% carbonyl iron), dietary iron deficiency (gastric parietal cell ablation), and HH (HFE -/-). Northern blot analyses demonstrated distinct tissue-specific patterns of expression for TfR and TfR2, with TfR2 expressed highly only in liver where TfR expression is low. In situ hybridization demonstrated abundant TfR2 expression in hepatocytes. In contrast to TfR, TfR2 expression in liver was not increased in iron deficiency. Furthermore, hepatic expression of TfR2 was not down-regulated with dietary iron loading or in the HFE -/- model of HH. From these observations, we propose that TfR2 allows continued uptake of Tf-bound iron by hepatocytes even after TfR has been down-regulated by iron overload, and this uptake contributes to the susceptibility of liver to iron loading in HH.

Amino Acid Sequence↗
PubMed1998

Could long-term alimentary iron overload have an impact on the parameters of oxidative stress? A study on the basis of a village in southern Estonia.

The effects of long-term alimentary (drinking water) iron overload on the parameters of oxidative stress were evaluated. The study group (n = 35) from a village in southern Estonia was 37.1 +/- 13.3 years old, and the mean period of drinking water iron overload was 20.6 +/- 9.3 years. The serum iron content was significantly higher than normal. The total iron-binding capacity of serum tended to be lowered. There was no change in the transferrin content. The parameters of lipid peroxidation like conjugated dienes and thiobarbituric acid reactive substances showed also significant differences. In addition, the red blood cell glutathione content was also decreased. The total antioxidant capacity of serum was not changed. It can be concluded from our results that a long-term alimentary iron overload results in a positive serum iron balance, which, in turn, yields an increased oxidative stress.

Adult↗
PubMed2003

Labile plasma iron in iron overload: redox activity and susceptibility to chelation.

Plasma non-transferrin-bound-iron (NTBI) is believed to be responsible for catalyzing the formation of reactive radicals in the circulation of iron overloaded subjects, resulting in accumulation of oxidation products. We assessed the redox active component of NTBI in the plasma of healthy and beta-thalassemic patients. The labile plasma iron (LPI) was determined with the fluorogenic dihydrorhodamine 123 by monitoring the generation of reactive radicals prompted by ascorbate but blocked by iron chelators. The assay was LPI specific since it was generated by physiologic concentrations of ascorbate, involved no sample manipulation, and was blocked by iron chelators that bind iron selectively. LPI, essentially absent from sera of healthy individuals, was present in those of beta-thalassemia patients at levels (1-16 microM) that correlated significantly with those of NTBI measured as mobilizer-dependent chelatable iron or desferrioxamine chelatable iron. Oral treatment of patients with deferiprone (L1) raised plasma NTBI due to iron mobilization but did not lead to LPI appearance, indicating that L1-chelated iron in plasma was not redox active. Moreover, oral L1 treatment eliminated LPI in patients. The approach enabled the assessment of LPI susceptibility to in vivo or in vitro chelation and the potential of LPI to cause tissue damage, as found in iron overload conditions.

Ascorbic Acid↗
PubMed2005

The evolution of iron chelators for the treatment of iron overload disease and cancer.

The evolution of iron chelators from a range of primordial siderophores and aromatic heterocyclic ligands has lead to the formation of a new generation of potent and efficient iron chelators. For example, various siderophore analogs and synthetic ligands, including ICL670A [4-[3,5-bis-(hydroxyphenyl)-1,2,4-triazol-1-yl]-benzoic acid], 4'-hydroxydesazadesferrithiocin, and Triapine, have been developed from predecessors and illustrate potent iron-mobilizing or antineoplastic activities. This review focuses on the evolution of iron chelators from initial lead compounds through to the development of novel chelating agents, many of which show great potential to be clinically applied in the treatment of iron overload disease and cancer.

Animals↗
PubMed2005

Macular degeneration in a patient with aceruloplasminemia, a disease associated with retinal iron overload.

PURPOSE: To provide the first ophthalmic case report of a Caucasian patient with the rare autosomal recessive disease aceruloplasminemia, which results in iron overload in the retina, brain, and pancreas. DESIGN: Single observational case report. METHODS: Perls' staining of a conjunctival biopsy was used to detect elevated iron levels in the conjunctival epithelium. Fundus photography, fluorescein angiography, and electroretinography were used to document retinal appearance and function. RESULTS: Unlike a report of a Japanese patient with aceruloplasminemia, who had midperipheral retinal pigment epithelium (RPE) cell atrophy and yellowish discoloration of the fundus, our Caucasian patient had a maculopathy. Beginning at age 47, he had development and progression of multiple subretinal yellowish-white lesions and RPE cell atrophy. To confirm tissue iron overload in our patient, we took the novel approach of a conjunctival biopsy, which showed Perls' Prussian blue-positive epithelial cells. CONCLUSIONS: Given our recent finding of elevated iron levels in the RPE of patients with age-related macular degeneration (AMD), it is interesting that retinal iron overload in aceruloplasminemia is associated with a maculopathy that clinically resembles AMD. This finding supports the hypothesis that retinal iron homeostasis is essential for normal retinal function. Disruption of iron homeostasis could contribute to the pathogenesis of AMD.

Anemia, Iron-Deficiency↗
PubMed2000

Transferrin saturation phenotype and HFE genotype screening for hemochromatosis and primary iron overload: predictions from a model based on national, racial, and ethnic group composition in central Alabama.

There is interest in general population screening for hemochromatosis and other primary iron overload disorders, although not all persons are at equal risk. We developed a model to estimate the numbers of persons in national, racial, or ethnic population subgroups in Jefferson County, Alabama, who would be detected using transferrin saturation (phenotype) or HFE mutation analysis (genotype) screening. Approximately 62% are Caucasians, 37% are African Americans, and the remainder are Hispanics, Asians, or Native Americans. The predicted phenotype frequencies are greatest in a Caucasian subgroup, ethnicity unspecified, which consists predominantly of persons of Scotch and Irish descent (0.0065 men, 0.0046 women), and in African Americans (0.0089 men, 0.0085 women). Frequencies of the HFE genotype C282Y/C282Y > or = 0.0001 are predicted to occur only among Caucasians; the greatest frequency (0.0080) was predicted to occur in the ethnicity-unspecified Caucasian population. C282Y/C282Y frequency estimates were lower in Italian, Greek, and Jewish subgroups. There is excellent agreement in the numbers of the ethnicity-unspecified Caucasians who would be detected using phenotype and genotype criteria. Our model also indicates that phenotyping would identify more persons with primary iron overload than would genotyping in our Italian Caucasian, Hispanic, and African American subgroups. This is consistent with previous observations that indicate that primary iron overload disorders in persons of southern Italian descent and African Americans are largely attributable to non-HFE alleles. Because the proportions of population subgroups and their genetic constitution may differ significantly in other geographic regions, we suggest that models similar to the present one be constructed to predict optimal screening strategies for primary iron overload disorders.

Alabama↗