PubMed Health⌕ Search

Biomedical subjects

Terri Gelbart

Publications and source records attributed to Terri Gelbart.

At least 19 recordsLinked to original sources
PubMed2006

Helicobacter pylori infection and HFE hemochromatosis.

Helicobacter pylori infections are associated with iron deficiency, even in the absence of bleeding. To determine whether H. pylori infection plays a role in modifying the phenotype of patients homozygous for the c.845 G > A (C282Y) mutation of the HFE gene we studied 79 homozygous women and 76 homozygous men, comparing the pretreatment hemoglobin, MCV, serum ferritin, transferrin saturation of those who were seropositive and seronegative for H. pylori. No difference between seropositive and seronegative homozytoes was found. There was also no difference between seropositive and seronegative control subjects. We also compared the total iron of 56 of the male and 32 of the female homozygotes as determined by serial phlebotomy. No significant difference was found.

Female↗
PubMed2006

Soluble transferrin receptor-1 levels in mice do not affect iron absorption.

Soluble transferrin receptor-1 (sTfR1) concentrations are increased in the plasma under two conditions that are associated with increased iron absorption, i.e. iron deficiency and increased erythropoiesis. To determine the possible role of sTfR1 as a signaling mechanism for iron absorption, a hydrodynamic gene transfer technique was established to express transfected plasmid constructs of human sTfR1 (hsTfR1) and murine sTfR1 (msTfR1) from the livers of C57BL/6 mice. Iron absorption, serum iron levels and hepcidin expression were then measured. The hydrodynamic gene transfer technique proved to be an effective approach to achieving sustained expression of sTfR1 in mice. Although expression of high levels of sTfR1 significantly increased serum iron levels, repeated experiments showed that neither hsTfR1 nor msTfR1 had any effect on iron absorption or hepcidin mRNA expression levels. Thus, despite its attractiveness as a potential modifier of iron absorption, sTfR1 levels do not exert a regulatory effect on iron absorption.

Animals↗
PubMed2005

Chronic inflammation does not appear to modify the homozygous hereditary hemochromatosis phenotype.

The mechanism of excessive iron storage in patients with hereditary hemochromatosis caused by mutations of the HFE gene seems to be a failure to up-regulate hepcidin in the face of increased body iron. Since the cytokines IL-1 and IL-6 stimulate hepcidin transcription in the absence of HFE, chronic inflammatory states might counteract the effect of HFE mutations. We measured the pre-phlebotomy plasma levels of C reactive protein (CRP) and of interleukin 6 (IL-6) in homozygotes for the C282Y mutation of HFE. There was no difference in these levels in subjects with high iron stores than in those with low iron stores, suggesting that the phenotypic differences between such homozygotes is not appreciably affected by ongoing chronic inflammation.

C-Reactive Protein↗
PubMed2005

Regulation of hepcidin transcription by interleukin-1 and interleukin-6.

Hepcidin is a peptide that regulates iron homeostasis by inhibiting iron absorption by the small intestine and release of iron from macrophages. Its production is stimulated by iron overload and by inflammation. It has been suggested that IL-6 is the only cytokine that stimulates hepcidin transcription. However, mice with targeted disruption of the gene encoding IL-6 (IL-6-/-) respond to endotoxin by increasing the expression of hepcidin transcripts in the liver. We show that incubating murine hepatocytes with IL-6, IL-1alpha, and IL-1beta strongly stimulates hepcidin transcription. IL-10 has little or no stimulatory effect, and IFN-beta inhibits transcription of hepcidin. All of the hepcidin stimulatory activity of macrophages from IL-6-/- mice can be accounted for by IL-1 that they secrete. Hepatocytes from IL-6-/- mice, hfe-/- mice, and mice with a hypomorphic transferrin receptor 2 mutation responded to IL-6 and IL-1 by up-regulating hepcidin transcription. Nitric oxide does not seem to be involved in the stimulation of hepcidin transcription by cytokines: aminoguanidine does not inhibit the stimulation of hepcidin transcription by cytokines. IL-1 may play a significant role in the anemia of inflammation by up-regulating hepcidin.

Animals↗
PubMed2004

The IL-6- and lipopolysaccharide-induced transcription of hepcidin in HFE-, transferrin receptor 2-, and beta 2-microglobulin-deficient hepatocytes.

The antimicrobial peptide hepcidin appears to play a central role in the regulation of iron homeostasis. In intact animals, iron overload or the injection of lipopolysaccharide (LPS) stimulates transcription of HAMP, the gene that encodes hepcidin. In isolated hepatocytes, IL-6, an inflammatory cytokine the production of which is stimulated by LPS, up-regulates transcription of hepcidin. In contrast, iron has no stimulatory effect on hepcidin expression in isolated hepatocytes. There is apparently a signaling pathway, activated by iron, that is present in the intact animal but not in isolated hepatocytes. Studies in humans and mice have shown that this iron-dependent pathway requires the presence of Hfe, hemojuvelin, and probably transferrin receptor 2 (tfr-2). To determine whether activation of hepcidin transcription by IL-6 also requires Hfe and tfr-2, we have studied mice homozygous for targeted disruption of HFE, beta(2)-microglobulin, and for a truncating mutation of TFR-2. We show that these mutant mice react normally to injection of endotoxin and that their isolated hepatocytes react normally to IL-6. This indicates that the signaling pathway activated by IL-6 does not require either Hfe or tfr-2. Mice with disruption of the gene encoding IL-6 seem to have a blunted response to LPS, but the statistical significance of the small response documented is borderline. It is therefore not clear whether LPS stimulates secretion of cytokines other than IL-6 that may stimulate hepcidin transcription.

Animals↗
PubMed2003

Haematological effects of the C282Y HFE mutation in homozygous and heterozygous states among subjects of northern and southern European ancestry.

High frequencies of the C282Y and H63D mutations of the HFE gene occur in European populations, even though homozygous and compound heterozygous states are associated with hereditary haemochromatosis, which is a disease that decreases fitness. This suggests that heterozygotes may possess a selective advantage. HFE mutations increase iron absorption in patients with haemochromatosis, and the mean transferrin saturations and ferritin levels are mildly increased in heterozygotes, suggesting that HFE mutations may protect against iron depletion and iron deficiency anaemia. In this study of 23,681 Caucasian adults, mean transferrin saturation, serum ferritin and haemoglobin levels were significantly higher in subjects carrying HFE mutations compared with wild types. Analysed by ethnicity, mean haemoglobin and mean erythrocyte volume (MCV) were significantly lower in those with a southern versus northern European ancestry. C282Y mutation carriers had an increased mean haemoglobin level in both ethnic groups. Prevalence of non-anaemic iron deficiency was significantly lower among female carriers of the C282Y mutation compared with HFE wild types. However, prevalence of frank iron deficiency anaemia did not differ significantly among genotypes. Quantile:quantile plots showed a small but significant upward shift in the mid-range of the haemoglobin distribution among C282Y mutation carriers that was consistent with an increased mean haemoglobin level without significant changes in the anaemic range.

Adult↗
PubMed2002

Prevalence of coronary heart disease associated with HFE mutations in adults attending a health appraisal center.

PURPOSE: Mutations of the HFE gene that cause hereditary hemochromatosis may be associated with an increased risk of cardiovascular disease. We examined the relation between two HFE mutations (C282Y and H63D), indicators of iron homeostasis, and the prevalence of coronary heart disease in a large population of white adults. SUBJECTS AND METHODS: We conducted a cross-sectional study of 30,916 white adults aged 25 to 98 years who attended a health appraisal center and underwent screening for HFE mutations. Coronary heart disease and cardiovascular risk factors were ascertained by questionnaire and medical records. RESULTS: Overall, 12% (1798/15,362) of men and 7% (1074/15,554) of women had a history of coronary heart disease. Of 10 HFE genotypes tested (five genotypes by sex), only men with the C282Y/H63D genotype (compound heterozygotes) had a significantly higher prevalence of coronary heart disease compared with men with no HFE mutations (odds ratio = 1.6; 95% confidence interval: 1.1 to 2.4; P = 0.01) after adjusting for cardiovascular risk factors. Elevated serum ferritin levels (>250 ng/mL) were associated with a lower prevalence of coronary heart disease in men (10% [255/2209] vs. 12% [1515/12,461] in controls, P = 0.008), which was not significant after adjusting for use of aspirin and anticoagulants. There were no significant associations between elevated transferrin saturation in either men or women, or between elevated serum ferritin levels or HFE mutations in women, and the prevalence of coronary heart disease. CONCLUSION: The results do not support a consistent association between HFE mutations or serum iron indicators and the prevalence of coronary heart disease.

Adult↗
PubMed2002

Disruption of a novel regulatory element in the erythroid-specific promoter of the human PKLR gene causes severe pyruvate kinase deficiency.

We established the molecular basis for pyruvate kinase (PK) deficiency in a white male patient with severe nonspherocytic hemolytic anemia. The paternal allele exhibited the common PKLR cDNA sequence (c.) 1529G>A mutation, known to be associated with PK deficiency. On the maternal allele, 3 in cis mutations were identified in the erythroid-specific promoter region of the gene: one deletion of thymine -248 and 2 single nucleotide substitutions, nucleotide (nt) -324T>A and nt -83G>C. Analysis of the patient's RNA demonstrated the presence of only the 1529A allele, indicating severely reduced transcription from the allele linked to the mutated promoter region. Transfection of promoter constructs into erythroleukemic K562 cells showed that the most upstream -324T>A and -248delT mutations were nonfunctional polymorphisms. In contrast, the -83G>C mutation strongly reduced promoter activity. Site-directed mutagenesis of the promoter region revealed the presence of a putative regulatory element (PKR-RE1) whose core binding motif, CTCTG, is located between nt -87 and nt -83. Electrophoretic mobility shift assay using K562 nuclear extracts indicated binding of an as-yet-unidentified trans-acting factor. This novel element mediates the effects of factors necessary for regulation of pyruvate kinase gene expression during red cell differentiation and maturation.

Alleles↗
PubMed2002

Penetrance of 845G--> A (C282Y) HFE hereditary haemochromatosis mutation in the USA.

BACKGROUND: There has been much interest in screening populations for disease-associated mutations. A favoured candidate has been the HFE gene, mutations of which are the most common cause of haemochromatosis in the European population. About five people in 1000 are homozygotes for the 845G-->A mutation, but little is known of how many have mutation-caused clinical manifestations. METHODS: We screened 41038 individuals attending a health appraisal clinic in the USA for the 845G--> A and 187C-->G HFE mutations, and analysed laboratory data and data on signs and symptoms of haemochromatosis as elicited by questionnaire. FINDINGS: The most common symptoms of haemochromatosis, including poor general health, diabetes, arthropathies, arrhythmias, impotence, and skin pigmentation were no more prevalent among the 152 identified homozygotes than among the controls. The age distribution of homozygotes and compound heterozygotes did not differ significantly from that of controls: there was no measurable loss of such individuals from the population during ageing. However, there was a significantly increased prevalence of a history of hepatitis or "liver trouble" among homozygotes and in the proportion of homozygotes with increased concentrations of serum aspartate aminotransferase and collagen IV; these changes were not related to iron burden or to age. Only one of the 152 homozygotes had signs and symptoms that would suggest a diagnosis of haemochromatosis. INTERPRETATION: The normal age distribution of people with the haemochromatosis genotype, and the lack of symptoms in patients of all ages, indicate that the penetrance of hereditary haemochromatosis is much lower than generally thought. The clinical penetrance of a disorder is an essential consideration in screening for genetic disease; disorders with low penetrance are more expensive candidates for screening than disorders with high penetrance. Our best estimate is that less than 1% of homozygotes develop frank clinical haemochromatosis.

Adult↗
PubMed2002

Polymorphisms in iron-responsive binding protein 2 and lack of association with sporadic Parkinson's disease.

Mice with targeted disruptions in the iron-responsive binding protein 2 (IRP2) gene accumulate iron in distinct regions of the brain and develop neurodegenerative characteristics resembling Parkinson's disease after 6 months of age. To determine whether polymorphisms in IRP2 predispose humans to Parkinson's disease (PD), we sequenced the IRP2 gene of subjects with sporadic PD and normal controls. Three polymorphisms which result in an amino acid change were identified: L159V, F272L, and T560I. The L159V and T560I polymorphisms, identified in an African-American PD subject, were found in the African-American population at an allele frequency of 0.102 (n = 1,236) and 0.111 (n = 1,228), respectively, and were not associated with an increased prevalence of PD. The F272L polymorphism was found in a normal 58-year-old, Caucasian subject whose father had PD, but it was not observed in 38 additional patients with sporadic PD. The F272L polymorphism occurred at an allele frequency of 0.0014 (n = 1,384) in the normal Caucasian population. Additional F272L heterozygous subjects identified in the normal population did not have a family or personal history of PD. We conclude that these IRP2 polymorphisms do not play an important role in the development of sporadic cases of PD. It remains to be determined whether other polymorphisms in IRP2 play a role in familial PD.

Aged↗
PubMed2002

Relationship of body iron stores to levels of serum ferritin, serum iron, unsaturated iron binding capacity and transferrin saturation in patients with iron storage disease.

None of the methods for assessing total body iron burden in patients with hemochromatosis is satisfactory. Although it is commonly believed that a relationship exists between serum ferritin levels and total iron burden, the extent of this relationship has not previously been documented. In the present investigation we measured the total body iron burden of 88 patients with putative hemochromatosis, 54 of whom were homozygotes for the 845G-->A (C282Y) mutation. The total body iron stores were estimated from the volume of red cells removed during therapeutic phlebotomy corrected for an estimated 2 mg/day dietary iron absorbed during the phlebotomy period; the amount of storage iron was compared to the serum ferritin, serum iron, unsaturated iron binding capacity, and transferrin saturation before the beginning of phlebotomy. The serum ferritin proved to be the best predictor of body iron stores. The correlation between all of the analytes and the body iron burden was greater in patients homozygous for the C282Y mutation than in those who were not, including the compound heterozygotes for C282Y and H63D. The body iron burden tended to be greater in patients homozygous for the C282Y mutation than the other patients at any other given ferritin level. We conclude that the serum ferritin level does provide some information regarding total iron burden but even in the case of C282Y homozygotes, the correlation is not very strong.

Ferritins↗
PubMed2002

Prevalence of hemochromatosis-related symptoms among individuals with mutations in the HFE gene.

OBJECTIVE: To determine the prevalence of hemochromatosis-related symptoms in homozygotes for the HFE mutation C282Y compared with controls without HFE mutations identified through a large screening program of subjects attending a health appraisal center. SUBJECTS AND METHODS: Presence of symptoms commonly associated with clinical hemochromatosis was ascertained by self-report on a written questionnaire among C282Y homozygotes and HFE wild-type subjects of white or Hispanic ethnicity identified from screening 41,599 adult subjects between March 1999 and August 2001. A subset of C282Y homozygotes and wild-type subjects identified from 12,756 subjects attending the center in the final year of the study completed a standardized double-blind interview with a physician regarding the presence, duration, and severity of a larger set of symptoms. Prevalence of symptoms among C282Y homozygotes and wild-type controls ascertained by written questionnaire and interview were compared by chi2 analysis or Fisher exact test. Symptoms among subjects with other combinations of the C282Y and H63D HFE mutations were also assessed by questionnaire. RESULTS: The 124 C282Y homozygotes who filled out the written questionnaire and the 17 C282Y homozygotes who completed the physician double-blind interview reported no significantly higher rates of arthritis or joint pain, abdominal pain, arrhythmias, darkening of skin, or other symptoms traditionally associated with hemochromatosis compared with the 22,429 wild-type controls who filled out the written questionnaire and 29 wild-type controls who completed the double-blind interview. The only symptom reported more frequently by C282Y homozygotes was loss of body hair, reported by 5 C282Y/C282Y female subjects compared with 1 wild-type male subject (P=.02) in the physician interview. Symptoms among subjects with other HFE genotypes were similar to symptoms of wild-type subjects. CONCLUSIONS: Results of this study indicate that many of the symptoms associated with hemochromatosis are common among HFE wild types and that clinical penetrance of the C282Y/C282Y genotype in regard to these symptoms is low.

Adult↗
PubMed2002

Haptoglobin polymorphism and iron homeostasis.

BACKGROUND: There is a marked difference in the degree of expression of the homozygous C282Y HFE genotype that is associated with hereditary hemochromatosis. It has been reported that individuals with the haptoglobin 2-2 type manifest increased iron concentrations, including serum iron, transferrin saturation, and ferritin. METHODS: We studied 232 patients, 115 homozygous for the c.845G-->A (C282Y) mutation and 117 matched controls with the wild-type HFE genotype, for haptoglobin phenotypes. Haptoglobin types were determined by electrophoresis of the denatured protein. The HFE genotype was determined by allele-specific oligonucleotide hybridization. Ferritin and transferrin saturation were measured by standard methods. RESULTS: There was no relationship between haptoglobin type and ferritin concentration or transferrin saturation. CONCLUSIONS: The effect of haptoglobin type on iron homeostasis cannot account for the marked phenotypic variation that is seen in patients homozygous for the HFE C282Y mutation.

Genotype↗
PubMedDate not supplied

Severe jaundice in a patient with a previously undescribed glucose-6-phosphate dehydrogenase (G6PD) mutation and Gilbert syndrome.

A patient with chronic hemolytic anemia and G6PD deficiency was noted to be severely jaundiced and to have a high serum ferritin level. Analysis of his DNA revealed only heterozygosity for the c.187 C-->G (H63D) mutation of HFE, but showed that he was homozygous for the UDP glucuronosyltransferase promoter mutation of Gilbert's disease and that he had a previously undescribed mutation of G6PD, c.832 T-->C (Ser278Pro). The new variant was named G6PD La Jolla.

Adult↗