Impedance-based Real-time Monitoring of Neural Stem Cell Differentiation

We present here the first impedance-based characterization of the differentiation process of two human mesencephalic fetal neural stem lines. The two dopaminergic neural stem cell lines used in this study, Lund human mesencephalic (LUHMES) and human ventral mesencephalic (hVM1 Bcl-X_L), have been developed for the study of Parkinsonian pathogenesis and its treatment using cell replacement therapy. We show that if only relying on impedance magnitude analysis, which is by far the most usual approach in, e.g., cytotoxicity evaluation and drug screening applications, one may not be able to distinguish whether the neural stem cells in a population are proliferating or differentiating. However, the presented results highlight that equivalent circuit analysis can provide detailed information on cellular behavior, e.g. simultaneous changes in cell morphology, cell-cell contacts, and cell adhesion during formation of neural projections, which are the fundamental behavioral differences between proliferating and differentiating neural stem cells. Moreover, our work also demonstrates the sensitivity of impedance-based monitoring with capability to provide information on changes in cellular behavior in relation to proliferation and differentiation. For both of the studied cell lines, in already two days (one day after induction of differentiation) equivalent circuit analysis was able to show distinction between proliferation and differentiation conditions, which is significantly earlier than by microscopic imaging. This study demonstrates the potential of impedance-based monitoring as a technique of choice in the study of stem cell behavior, laying the foundation for screening assays to characterize stem cell lines and testing the efficacy epigenetic control.

Combined Use of DNA Probes in First-Trimester Prenatal Diagnosis of Hemophilia A

First-trimester prenatal diagnoses of hemophilia A were heretofore obtained by using either intragenic factor VIII markers or linked cxtragcnic polymorphic markers. Postulating that the combined use of all the available intragenic and extragenic markers can render such diagnoses more frequently feasible and more reliable, we carried out ten first-trimester prenatal diagnoses in male fetuses at risk for hemophilia A by DNA analysis of chorionic villus employing in combination the intragenic Bcl I polymorphism and the St 14 (DXS 52) or DX 13 (DXS 15) extragenic probes. A diagnosis of hemophilia was obtained in three fetuses, with a diagnosis of normal fetus obtained in the remaining seven. Seven diagnoses are confirmed by factor VIII assays carried out at the time of abortion, in the mid-Trimester or at birth. A factor VIII probe recognizing Bcl I polymorphism was useful in 4 of 6 diagnoses; St 14, in 5 of 6; and DX 13 in 3 of 5. In two cases, St 14 was the only useful probe for diagnosis. Even though no recombination between extragenic probes and factor VIII gene was detected in this study, when only extragenic markers were informative we advised diagnostic confirmation on fetal plasma obtained by fetoscopy. Hence, first-trimester prenatal diagnosis of hemophilia A is feasible for the great majority of fetuses at risk through combined use of all the available intragenic and extragenic probes, providing key family members are available.

Note: Differential configurations for the mitigation of slow fluctuations limiting the resolution of digital lock-in amplifiers

The resolution of digital lock-in amplifiers working with a narrow bandwidth (<100 Hz) is limited by slow fluctuations, which can be two orders of magnitude larger (μV range) than the noise of the input amplifier (tens of nV). In order to tackle this issue, affecting state-of-the-art laboratory instrumentation and here systematically quantified, three differential sensing configurations are presented. They adapt to different setup conditions and are based on manual and automatic tuning of dummy references, allowing a 25-fold resolution improvement for enhanced long-term tracking of impedance sensors.

A compact multifunctional microfluidic platform for exploring cellular dynamics in real-time using electrochemical detection

Dopamine detection from PC12 cell populations and monitoring of yeast redox metabolism demonstrate the multifunctionality of the compact microfluidic cell culture and electrochemical analysis platform with in-built fluid handling and detection unit.

Fully inkjet-printed organic photodetectors with high quantum yield

Bulk-heterojunction based organic photodetectors are fabricated by means of drop-on-demand inkjet printing with vertical topology, inverted structure, and small footprint (about 100 μm x 100 μm). Due to optimization of the deposition technique, an external quantum efficiency in excess of 80% at 525 nm and a -3dB bandwidth of a few tens of kHz is achieved.

Nanoscale capacitance imaging with attofarad resolution using ac current sensing atomic force microscopy

Nanoscale capacitance imaging with attofarad resolution (∼1 aF) of a nano-structured oxide thin film, using ac current sensing atomic force microscopy, is reported. Capacitance images are shown to follow the topographic profile of the oxide closely, with nanometre vertical resolution. A comparison between experimental data and theoretical models shows that the capacitance variations observed in the measurements can be mainly associated with the capacitance probed by the tip apex and not with positional changes of stray capacitance contributions. Capacitance versus distance measurements further support this conclusion. The application of this technique to the characterization of samples with non-voltage-dependent capacitance, such as very thin dielectric films, self-assembled monolayers and biological membranes, can provide new insight into the dielectric properties at the nanoscale.

Shot noise in linear macroscopic resistors

We report on direct experimental evidence of shot noise in a linear macroscopic resistor. The origin of the shot noise comes from the fluctuation of the total number of charge carriers inside the resistor associated with their diffusive motion under the condition that the dielectric relaxation time becomes longer than the dynamic transit time. The present results show that neither potential barriers nor the absence of inelastic scattering are necessary to observe shot noise in electronic devices.

Is hemochromatosis a risk factor for Alzheimer's disease?

Excess iron accumulation in the brain is a consistent observation in Alzheimer's Disease. Iron affects amyloid precursor protein (AbetaPP) processing and promotes deposition of Abeta. Iron is also among the most potent biological toxins because of its ability to react with oxygen to form reactive oxygen species. Consequently, elucidation of the mechanisms associated with maintaining brain iron homeostasis is fundamentally important to understanding the underlying pathogenesis in AD. The iron overload disorder, Hemochromatosis, is the most common genetic disorder (1:200) so a significant percentage of AD patients can be expected to carry this mutation. Heterozygotes for this mutation also have an increased, but sub-clinical iron burden. Given the high percentage of the population who are at significant risk for iron overload, we propose that the hemochromatosis mutation be considered as a confounding factor when evaluating the contribution of genetic associations with AD and treatment strategies and efficacy. Two recent papers and new evidence presented here that the protein associated with hemochromatosis is expressed on blood vessels, choroid plexus and the ependymal cells in the brain are offered as support for this proposal.

Autoantibodies to human cytosol: a marker of sporadic porphyria cutanea tarda

The enzymes potentially involved in the pathogenesis of sporadic porphyria cutanea tarda (PCT) reside in liver cytosoles and microsomes. PCT is frequently associated with hepatitis C virus (HCV) infection, which is in turn associated with autoimmune manifestations. To investigate whether autoimmune reactions, possibly triggered by HCV, are involved in the pathogenesis of PCT, we measured by immunoblot autoantibodies to human cytosolic and microsomal liver fractions in 82 patients with PCT (77% with HCV infection), 105 with other liver disorders and 40 healthy subjects. Anti-liver cytosolic antibodies were more frequent in PCT patients (38/82, 46%) than in pathological controls (P < 0.05-P < 0.001) or in healthy subjects (3/40, 8%, P < 0.001). Among PCT patients, anticytosolic antibodies were more frequent in HCV positive (36/63, 57%) than in HCV negative (2/19, 11%, P < 0.05) cases. Reactivity to a 40-kDa cytosolic polypeptide was present in 20 PCT patients (19 HCV positive), being more frequent than in all pathological controls (P < 0.01-P < 0.0001). Histological activity index (P = 0.04) and antibodies to HCV (P = 0.027) - but not HCV RNA - were associated independently with anticytosolic antibodies as assessed by multivariate analysis. In contrast, frequency of antiliver microsomal antibodies was similar in PCT patients (24/82, 29%) and pathological controls (8-26%), being higher in the autoimmune hepatitis control group (23/23, 100%, P < 0.0001). In conclusion, anticytosolic antibodies, particularly to a 40-kDa polypeptide, are frequent in PCT and associated with HCV infection and severity of liver damage.

Liver cancer risk is increased in patients with porphyria cutanea tarda in comparison to matched control patients with chronic liver disease

BACKGROUND/AIMS

Patients with porphyria and chronic liver disease could be at high risk of developing hepatocellular carcinoma. To define the incidence of primary liver cancer and identify variables associated with the risk of cancer in patients with porphyria cutanea tarda in comparison to control patients.

METHODS

Fifty-three patients with porphyria cutanea tarda were enrolled in a prospective study (median follow-up 72 +/- 54.1 months; range 12-216) and matched individually to a control case according to age (+/-5 years), sex, duration of follow up (+/- 5 years), severity of liver disease, and hepatitis C virus infection.

RESULTS

During follow-up hepatocellular carcinoma developed in 18 patients with porphyria and in four control patients. Incidence of primary liver cancer was 4.8 and 1.3 x 100 patients/year in the overall series of patients and of controls, respectively. The cumulative probability of being tumor free was significantly lower in porphyria cutanea tarda than in matched controls (75 vs 95%). Variables independently associated with the risk of liver cancer were the presence of porphyria and cirrhosis at enrollment (Odds ratios: 5.3, 95% CI 1.4-19.3 and 3.0, 95% CI 1.2-7.6, respectively).

CONCLUSIONS

Patients with porphyria are at higher risk of developing liver cancer than matched control patients.

Hyperferritinemia, iron overload, and multiple metabolic alterations identify patients at risk for nonalcoholic steatohepatitis

OBJECTIVE

The aim of this study was to define in patients with hyperferritinemia and normal transferrin saturation the relationships among hyperferritinemia, iron overload, HFE gene mutations, the presence of metabolic alterations, and nonalcoholic steatohepatitis (NASH).

METHODS

Forty patients with increased serum ferritin, resistant to dietary restriction and normal transferrin saturation, 90 with ultrasonographic evidence of hepatic steatosis, and 60 obligate heterozygotes for hemochromatosis, all negative for alcohol abuse, hepatitis virus infections, and inflammation were studied. Transferrin saturation, serum ferritin, uric acid, lipids, glucose tolerance, insulin resistance, HFE gene mutations, liver histology, and hepatic iron concentration were analyzed.

RESULTS

Of the 40 patients with hyperferritinemia, 29 (72%) had biochemical metabolic abnormalities, 18 of the 26 examined (69%) had insulin resistance, 26 (65%) had the presence of one of the two HFE gene mutations (normal controls, 33 of 128 [26%], p < 0.0001), and all had increased liver iron concentration. Thirty-one patients (77%) had histology compatible with NASH. At univariate analysis, NASH was significantly associated with the presence of metabolic alterations, the C282Y mutation, and severity of fibrosis. At multivariate analysis, NASH was associated with the coexistence of multiple metabolic alterations (odds ratio = 5.2, 95% CI = 0.95-28.7). The risk of having NASH augmented in the presence of higher values of ferritin and liver iron concentration. Among the 90 patients with ultrasonographic evidence of hepatic steatosis, 24 (27%) had increased serum ferritin with normal transferrin saturation, but only six remained hyperferritinemic after dietary restriction.

CONCLUSION

Increased ferritin with normal transferrin saturation is frequently found in patients with hepatic steatosis, but it reflects iron overload only in those patients in whom it persists despite an appropriate diet. The simultaneous disorder of iron and glucose and/or lipid metabolism, in most of the cases associated with insulin resistance, is responsible for persistent hyperferritinemia and identifies patients at risk for NASH.

The hemochromatosis gene affects the age of onset of sporadic Alzheimer's disease

In the present study we analysed the genotype of HFE, the gene involved in hemochromatosis, in 107 patients with sporadic late-onset AD and in 99 age-matched non-demented controls. We observed that patients carrying the mutant HFE-H63D allele had a mean age at onset of 71.7 +/- 6.0 years versus 76.6 +/- 5.8 years of those who were homozygous for the wild-type allele (p = 0.001). The frequency of the HFE-H63D mutation was highest (0.22) in the patients aged <70 years at the time of disease onset, whereas it was 0.12 in those with disease onset at an age of 70-80 years, and 0.04 in those aged more than 80 years. The APOE genotype did not significantly modify the effect of HFE on age at onset. We conclude that mild disturbances of iron homeostasis associated with a common genetic determinant may interact with other pathogenic mechanisms involved in AD. HFE mutations may anticipate AD clinical presentation in susceptible individuals.

Tumor necrosis factor alpha promoter polymorphisms influence the phenotypic expression of hereditary hemochromatosis

Severe iron overload usually develops in patients with hereditary hemochromatosis (HHC), but variability in the phenotypic expression of the disease has been reported. This study assessed whether tumor necrosis factor alpha (TNF-alpha) plays a role in phenotypic expression of HHC. Sixty-four patients with HHC and 172 healthy volunteers (controls) were studied. Release of TNF-alpha from stimulated peripheral blood monocytes was measured by enzyme-linked immunosorbent assay, and 308 and 238 TNF-alpha polymorphisms were detected with polymerase chain reaction and restriction fragment-length polymorphism analysis. The relation between TNF-alpha polymorphisms and clinical expression of HHC was evaluated. Patients with HHC released less TNF-alpha than controls, but the difference was significant only in homozygotes for the C282Y mutation. The prevalence of the 308 TNF-alpha polymorphism was similar in patients and controls, whereas the prevalence of the 238 polymorphic allele was significantly lower in patients (3% versus 16%; P =.002). A lower prevalence of cirrhosis was observed in patients with TNF-alpha polymorphism than in those without it (4 of 15 [27%] versus 28 of 49 [57%]), but the difference was not significant (P =.07). In nonhomozygotes for the C282Y mutation, severe liver siderosis was less prevalent in patients with the 308 polymorphism than in those without it (P =.05). Alanine aminotransferase (ALT) values were significantly lower in patients with TNF-alpha polymorphism (P =.006), even when patients with other hepatotoxic factors were excluded. Multivariate analysis showed that TNF-alpha polymorphism was independently associated with ALT values (P =.0008 and P =.045, respectively, in homozygotes and nonhomozygotes for the C282Y mutation) and siderosis in nonhomozygotes (P =.047). Thus, TNF-alpha appears to play a role in HHC by modulating the severity of liver damage. (Blood. 2001;97:3707-3712)

Iron status and HFE genotype in erythrocyte pyruvate kinase deficiency: study of Italian cases

We evaluated the iron status and searched for mutations C282Y and H63D in the hereditary hemochromatosis gene (HFE) in 34 pyruvate kinase (PK)-deficient patients from 29 unrelated families. Nine had received multiple transfusions. Thirteen of the 25 nontransfused patients displayed increased serum ferritin concentration, in the absence of conditions known to raise this parameter. HFE genotype was abnormal in 9 of 34 patients. The allele frequency was 1.8% for mutation 845G--> (C282Y) and 16.1% for mutation 187C-->G (H63D). Nontransfused subjects with abnormal genotype had serum ferritin and transferrin saturation values significantly higher than those with wild-type genotype. Of the 12 adult nontransfused patients with increased iron status parameters, 1 was C282Y homozygous, 1 compound heterozygous for C282Y and H63D, 3 H63D heterozygous, and 7 had a normal HFE genotype. Serum ferritin and transferrin saturation were not related to hemoglobin, reticulocytes, and bilirubin concentration. At multivariate analysis serum ferritin was independently associated with age and gender, but not with splenectomy and HFE genotypes. The retrospective evaluation of the iron status profile of 10 patients (3 with abnormal and 7 with wild-type HFE genotype) with at least 10 years follow-up showed that overt iron accumulation requiring iron chelation had occurred only in the 3 patients (2 of whom were splenectomized) with the mutated HFE gene.

Mutations in the HFE gene and their interaction with exogenous risk factors in hepatocellular carcinoma

The possible role of iron in facilitating the development of liver cancer is still debated. The aims of this study were to define the prevalence of the mutations 845G --> A and 187C --> G (C282Y and H63D) in the HFE gene associated with hereditary hemochromatosis in Italian patients with hepatocellular carcinoma occurring in cirrhosis and to analyze the interaction between these mutations and other established risk factors for hepatocellular carcinoma. The HFE gene mutations, performed by polymerase chain reaction, were analyzed in 81 patients (63 males, 18 females) with hepatocellular carcinoma. None of the patients had a phenotype compatible with homozygous hereditary hemochromatosis. Interaction between HFE mutations and exogenous risk factors was analyzed by collecting information on alcohol consumption, hepatitis B and C virus infections, and iron status at the time of diagnosis of chronic liver disease. This analysis was performed only in males to rule out gender influence on patients' iron status by using the case-only approach specifically designed to estimate departure from multiplicative risk ratios under the assumption of independence between genotype and environmental exposure. The prevalence of the C282Y mutation was significantly higher in patients with hepatocellular carcinoma than in normal controls (8.6% vs 1.6%, P < 0.03). At univariate analysis, iron overload was significantly associated with both HFE mutations (P < 0.0001), whereas ongoing hepatitis B virus infection was associated with the C282Y mutation (P < 0.05). By multivariate analysis, a trend for an increased risk of being positive for hepatitis virus markers (OR 2.9, CI 95% 0.9-9.5) and of having been alcohol abusers (OR 3, CI 95% 0.7-14) was observed in patients heterozygous for the HFE mutations. These data indicate that the prevalence of the main mutation associated with hereditary hemochromatosis is significantly higher in cirrhotic Italian patients with hepatocellular carcinoma compared to a normal population and suggest that heterozygotes for HFE mutations exposed to hepatitis virus infections or who had been alcohol abusers could have an increased risk of developing cirrhosis and later liver cancer than people without the mutations exposed to the same risk factors.

Haemochromatosis in patients with beta-thalassaemia trait

Severe iron overload has been reported in patients with the beta-thalassaemia trait. Studies performed before the discovery of the haemochromatosis gene (HFE) have yielded conflicting results: some suggest that iron overload might arise from the interaction of the beta-thalassaemia trait with heterozygosity for haemochromatosis, some with homozygosity for haemochromatosis and others that it was unrelated to haemochromatosis. We have studied the clinical phenotype, iron indices and HFE genotypes of 22 unrelated patients with the beta-thalassaemia trait and haemochromatosis, the inheritance of chromosome 6p and 1q haplotypes in families of non-homozygous C282Y probands and serum measures of iron status in relatives heterozygous for C282Y with or without the beta-thalassaemia trait. We demonstrate that the beta-thalassaemia trait aggravates the clinical picture of C282Y homozygotes, favouring higher rates of iron accumulation and the development of severe iron-related complications. We suggest that the coexistence of the beta-thalassaemia trait might also increase the risk of iron overload in patients with HFE genotypes at a mild risk of haemochromatosis. Our findings do not support the hypothesis that the association of the beta-thalassaemia trait with a single C282Y or H63D allele might lead to iron overload and suggest that other non-HFE-related inherited factors are present in haemochromatosis patients with incomplete HFE genotypes.

TT virus infection in adult beta-thalassemia major patients

BACKGROUND AND OBJECTIVES

Patients with thalassemia-major are at risk of blood-borne viral infections. TT virus (TTV), a single stranded, circular DNA virus, has recently been found to be associated with acute and chronic hepatitis. The aims of this study were to assess the prevalence of TTV infection in adult patients with transfusion-dependent thalassemia, and to evaluate the clinical significance of TTV.

DESIGN AND METHODS

We studied 68 adult patients with thalassemia major, 97% of whom were hepatitis C virus (HCV) antibody positive. TTV DNA was amplified from serum by heminested polymerase chain reaction (PCR). Direct sequencing of PCR products was used to establish TTV genotypes.

RESULTS

TTV DNA was detected in 47 patients (69.1%). Sequence analysis of PCR products identified TTV genotype 1b as the most common viral genotype in this group. Patients co-infected by HCV and TTV had a significantly higher histologic grade score than patients with isolated HCV infection (5.1+/-2.7 vs. 2.8+/-1.7, p=0.02) while the stage score was not significantly different.

INTERPRETATION AND CONCLUSIONS

TTV is highly prevalent among Italian multiply transfused patients. In these patients TTV viremia appears to affect the necro-inflammatory activity of hepatitis C, though no evidence of an effect on the evolution of fibrosis was found.

Hereditary hemochromatosis in a patient with congenital dyserythropoietic anemia

Herein is described the case of a young woman presenting with iron overload and macrocytosis. The initial diagnosis was hereditary hemochromatosis. Severe anemia developed after a few phlebotomies, and she was also found to have congenital dyserythropoietic anemia that, though not completely typical, resembled type II. Only genetic testing allowed the definition of the coexistence of the 2 diseases, both responsible for the iron overload. This report points out the need to consider congenital dyserythropoietic anemia in patients with hemochromatosis and unexplained macrocytosis and, conversely, to check for the presence of hereditary hemochromatosis in patients with congenital dyserythropoietic anemia and severe iron overload. To the authors' knowledge, this is the first report of homozygosity for the C282Y mutation of the HFE gene in a patient affected by congenital dyserythropoietic anemia.

Immunohistochemistry of HFE in the duodenum of C282Y homozygotes with antisera for recombinant HFE protein

BACKGROUND AND OBJECTIVE

HFE is a class-I MHC related protein which carries the C282Y mutation in most patients with hereditary hemochromatosis, an iron overload disease. HFE protein is expected to have a relevant role in the regulation of duodenal iron absorption, and HFE protein was immunohistochemically identified in the crypt cells. The aim of the work was to analyze whether the C282Y mutation affects HFE accumulation in the duodenum.

DESIGN AND METHODS

We developed antisera for the extracellular portion of recombinant human HFE protein expressed in E. coli. The antisera were specific for HFE protein and the C282Y mutant in immunoblotting, immunoprecipitation and immunocytochemistry experiments of transfected cells, and they did not cross react with HLA antigens in various analyses. The antisera gave positive results in the staining of paraffin-fixed sections of duodenal slices of subjects with hemochromatosis.

RESULTS

The antisera stained evident supranuclear granules in all enterocytes of 7 C282Y homozygous subjects, and a dark area in the same region in 3 other C282Y homozygotes. Granular bodies were absent from the duodenal sections of 8 C282Y negative subjects, from 2 C282Y heterozygotes and 3 C282Y homozygotes, with or without hemochromatosis.

INTERPRETATION AND CONCLUSIONS

The detection of HFE-protein in granular bodies in the enterocytes of the large majority (77%) of C282Y homozygotes and not in other subjects suggests that the mutation facilitates protein accumulation in the duodenum.

Inherited HFE-unrelated hemochromatosis in Italian families

Hemochromatosis (HH) is usually caused by the homozygous state for C282Y mutation in the HFE gene. A minority of iron loaded patients have no mutations in this gene. An infrequent subset shows an early-onset aggressive disorder, denoted juvenile hemochromatosis (JH), which has no linkage to 6p. In this report we describe six patients from three unrelated Italian families, four men and two women, aged 21 to 44 with the typical hemochromatosis phenotype, who are homozygous for the wild type allele at the HFE gene. In two families the disorder is unlinked to 6p; in one family some features of the juvenile form are seen, but linkage to 6p is not excluded. Our results point to genetic forms of hemochromatosis not associated with HFE and raise the problem of whether non-HFE hemochromatosis in Italy is related to the "juvenile" form. They also emphasize the importance of phenotypic as well as genetic diagnosis of HH.

Carbohydrate-deficient transferrin, a sensitive marker of chronic alcohol abuse, is highly influenced by body iron

Carbohydrate-deficient transferrin (CDT), a microheterogeneous form of serum transferrin (Tf), has been proposed as the most reliable marker of chronic alcohol consumption, although unexplained false-positive and -negative results have been reported. We investigated whether body iron influenced CDT serum levels by studying alcohol abusers with or without iron overload and nonabusers with iron deficiency or iron overload caused by genetic hemochromatosis (GH). In alcohol abusers, CDT was significantly lower in the presence of iron overload than in the absence (24.6 +/- 16.5 U/L vs. 33.3 +/- 11.7 U/L; P <.01), with false-negative results almost exclusively in patients with iron overload. Similarly, in nonabusers with GH, CDT was lower than in normal controls (9.6 +/- 2. 2 U/L vs. 15.7 +/- 3.3 U/L; P <.0001), whereas, patients with iron deficiency anemia had significantly higher levels than controls (28. 1 +/- 5.8 U/L vs. 15.7 +/- 3.3 U/L; P <.0001). In nonabusers, iron supplementation therapy significantly decreased CDT levels in patients with iron deficiency anemia (33.7 +/- 6.6 U/L vs. 21.7 +/- 5.2 U/L; P =.0007), while iron-depletion treatment significantly increased CDT levels in patients with GH (9.7 +/- 2.0 U/L vs. 14.7 +/- 4.0 U/L; P =.001). Alcohol abusers had a significant relationship between liver iron concentration (LIC) and the reciprocal of CDT (r =.65; P <.0001), while in nonabusers, there was a significant correlation between Tf and CDT (r =.72; P <.0001). In conclusion, CDT serum levels are markedly affected by the patient's iron status, with iron overload reducing its sensitivity in alcohol abusers and iron deficiency its specificity in nonabusers. CDT can be considered a reliable marker of alcohol abuse only when iron stores are normal.

Iron overload in porphyria cutanea tarda

BACKGROUND AND OBJECTIVE

Porphyria cutanea tarda (PCT) is a disorder of porphyrin metabolism associated with decreased activity of uroporphyrinogen decarboxylase (URO-D) in the liver. The relevance of iron in the pathogenesis of PCT is well established: iron overload is one of the factors that trigger the clinical manifestations of the disease and iron depletion remains the cornerstone of therapy for PCT. A role for genetic hemochromatosis in the pathogenesis of iron overload in PCT has been hypothesized in the past but only after the recent identification of the genetic defect causing hemochromatosis has the nature of this association been partially elucidated. This review will outline current concepts of the pathophysiology of iron overload in PCT as well as recent contributions to the molecular epidemiology of hemochromatosis defects in PCT.

EVIDENCE AND INFORMATION SOURCES

The authors of the present review have a long-standing interest in the pathogenesis, etiology and epidemiology of iron overload syndromes. Evidence from journal articles covered by the Science Citation Index(R) and Medline(R) has been reviewed and collated with personal data and experience.

STATE OF THE ART AND PERPECTIVES

Mild to moderate iron overload plays a key role in the pathogenesis of PCT. The recent identification of genetic mutations of the hemochromatosis gene (HFE) in the majority of patients with PCT confirms previous hypotheses on the association between PCT and hemochromatosis, allows a step forward in the understanding of the pathophysiology of the disturbance of iron metabolism in the liver of PCT patients, and provides an easily detectable genetic marker which could have a useful clinical application. Besides the epidemiological relevance of the association between PCT and hemochromatosis, however, it remains to be fully understood how iron overload, and in particular the cellular modifications of the iron status secondary to hemochromatosis mutations, affect the activity of URO-D, and how the altered iron metabolism interacts with the other two common triggers for PCT and etiological agents for the associated liver disease: alcohol and hepatitis viruses. The availability of a genetic marker for hemochromatosis will allow some of these issues to be addressed by studying aspects of porphyrins and iron metabolism in liver samples obtained from patients with PCT, liver disease of different etiology and different HFE genotypes, and by in vitro studies on genotyped cells and tissues.

Molecular pathology of Crigler-Najjar type I and II and Gilbert's syndromes

BACKGROUND AND OBJECTIVE

Crigler-Najjar syndromes type I and II and Gilbert's syndrome are familial unconjugated hyperbilirubinemias caused by genetic lesions involving a single complex locus encoding for bilirubin-UDP-glucuronosyltransferase which is involved in the detoxification of bilirubin by conjugation with glucuronic acid. Over the last few years a number of different mutations affecting this gene have been characterized. The aim of this work is to review the molecular pathology of Crigler-Najjar and Gilbert's syndromes, to discuss its impact on the clinical and genetic classification of these conditions, and on the diagnostic evaluation of clinical pictures associated with unconjugated hyperbilirubinemia.

EVIDENCE AND INFORMATION SOURCES

The authors of the present review are involved in the clinical management of patients with familial unconjugated hyperbilirubinemia as well as in the characterization of its molecular bases. Evidence from journal articles covered by the Science Citation Index and Medline has been reviewed and collated with personal data and experience.

STATE OF THE ART AND PERSPECTIVES

It has been known for many years that mild to severe deficiency of bilirubin UDP-glucuronosyltransferase in the liver is the cause of two types of familial unconjugated hyperbilirubinemia, Crigler-Najjar syndromes I and II, and Gilbert's syndrome. Since the characterization of the gene encoding for bilirubin UDP-glucuronosyltransferase, a number of mutations affecting the expression of this gene have been identified. These mutations can be classified into three groups: mutations which result in a reduced production of a normal enzyme; mutations which give rise to the synthesis of a structurally abnormal and dysfunctional enzyme; mutations which completely abolish the expression of the affected allele. The combination of mutations affecting the coding region of the gene and of promoter mutations which reduce the expression of the gene accounts for the wide clinical spectrum of familial unconjugated hyperbilirubinemias, ranging from the clinically negligible Gilbert's syndrome to the severe and often fatal Crigler-Najjar type I syndrome. A better understanding of the genetics of these conditions and the availability of molecular diagnosis will improve the diagnostic efficiency and afford better informed genetic counseling, not only for Crigler-Najjar and Gilbert's syndromes, but also for several acquired conditions characterized by unconjugated hyperbilirubinemia.

Hepatitis G virus infection in the elderly

BACKGROUND AND AIMS

At least 10% of post-transfusion and community-acquired hepatitis cases are not accounted for by the A to E viruses. Hepatitis G virus (HGV), a novel agent belonging to the Flaviviridae and distantly related to HCV has recently been identified. The epidemiology and clinical significance of this infection in the geriatric setting is still little known. Aim of the investigation was to assess the prevalence and clinical significance of HGV infection in the geriatric setting.

PATIENTS

105 unselected consecutive patients (mean age 73.4 years).

METHODS

HGV-RNA was detected by a single-tube reverse-transcription heminested polymerase chain reaction with primers from the 5' untranslated region of the virus. Anti-HGV antibodies were detected with a commercial anti-E2 immunometric assay.

RESULTS

3/105 patients (2.9%) were viraemic, without a history or clinical evidence of hepatitis. Anti-HGV antibodies were detected in 25 patients (23.8%), 40% of whom had associated anti-HCV antibodies. The presence of HGV-RNA and anti-HGV antibodies was mutually exclusive.

CONCLUSIONS

HGV infection is highly prevalent in our population and the cumulative risk of exposure is proportional to age. In most cases, HGV infection is self-limiting and clinically irrelevant. Immunity against E2 or other associated uncharacterized viral epitopes appears to be protective.

Heterogeneity of hemochromatosis in Italy

BACKGROUND & AIMS

Patients with hemochromatosis show variable phenotype expression. We evaluated the frequency of hemochromatosis gene (HFE) mutations and the contribution of HFE genotype, ancestral haplotype, ethnic background, and additional factors (alcohol intake, hepatitis viruses, and beta-thalassemia trait) to the severity of iron overload in a large series of Italian patients with a hemochromatosis phenotype.

METHODS

HFE genotype was studied in 188 patients. Phenotype evaluation was available in 153 men and 20 women and was based mainly on iron removed. HFE genotype was determined by a polymerase chain reaction restriction assay and ancestral haplotype through D6S265 and D6S105 microsatellite analysis.

RESULTS

The frequency of C282Y homozygotes was 64%, with a decreasing gradient from north to south. C282Y homozygotes showed more severe iron overload than the other HFE genotypes. In the same group, ancestral haplotype was associated with a more severe phenotype. Additional factors may favor the development of a relatively mild hemochromatosis phenotype in patients nonhomozygous for the C282Y mutation.

CONCLUSIONS

Hemochromatosis in Italy is a nonhomogenous disorder in which genetic and acquired factors are involved. In patients with a single or no HFE mutation, further studies will enable a differentiation between true genetic disorders and interactions between genetic and acquired factors.

TATA-box mutant in the promoter of the uridine diphosphate glucuronosyltransferase gene in Italian patients with Gilbert's syndrome

BACKGROUND

A mutation in the promoter of the uridine diphosphate glucuronosyltransferase gene has been described in patients with Gilbert's syndrome from Northern Europe.

AIMS

To assess the frequency of this mutation in Italian patients with Gilbert's syndrome and in normal controls, in order to establish the molecular basis and molecular epidemiology of the syndrome in Italy.

PATIENTS

Forty-six patients with a clinical diagnosis of Gilbert's syndrome and 44 individuals from the general population unselected for bilirubin levels.

METHODS

Polymerase chain reaction amplification of the TATA-box element in the promoter of uridine diphosphate glucuronosyltransferase and identification of wild-type and variant alleles by high-resolution polyacrylamide gel electrophoresis.

RESULTS

A TATA-box variant in the promoter of uridine diphosphate glucuronosyltransferase was found on 93% of chromosomes from patients with Gilbert's syndrome. The same variant was present on 44% of chromosomes from controls, unselected for bilirubin levels. Only 55% of controls homozygous for the TATA-box variant, however, had increased bilirubin levels.

CONCLUSIONS

The TATA-box variant in the promoter of uridine diphosphate glucuronosyltransferase is strongly associated with the phenotype of Gilbert's syndrome in Italy. The incomplete penetrance of the mutation observed in controls indicates that other acquired or inherited conditions affecting bilirubin production, uptake, cellular transport or excretion may contribute to the hyperbilirubinaemia of Gilbert's syndrome.

High prevalence of the His63Asp HFE mutation in Italian patients with porphyria cutanea tarda

Sporadic porphyria cutanea tarda (PCT) is caused by a reduced activity of uroporphyrinogen decarboxylase (URO-D) in the liver. Mild to moderate iron overload is common in PCT, as iron is one of the factors which trigger the clinical manifestations of the disease through the inactivation of URO-D. A role for genetic hemochromatosis in the development of iron overload in sporadic PCT has been hypothesized in the past. The aim of this work was to investigate whether mutations of HFE, which is a candidate gene for hemochromatosis, play the role of genetic susceptibility factors for PCT in Italian patients, who have a high prevalence of acquired triggering factors, such as hepatitis C virus (HCV) chronic infection and alcohol. We determined HFE genotypes of 68 male patients with PCT. Our data do not confirm an association of PCT with the Cys282Tyr HFE mutation, strongly associated with hemochromatosis in Northern European countries. A second mutation of HFE, His63Asp, however, had a significantly increased frequency as it was present in half of the patients. Surprisingly, the presence of the His63Asp mutation was not related to the iron status of patients, suggesting that a subtle abnormality of iron metabolism induced by this mutation could escape detection by the standard parameters of iron status. In PCT patients with liver disease, the presence of the mutation could contribute to the inactivation of URO-D, either directly or through a synergistic action with other factors that cause liver damage.

High prevalence of hepatitis C virus type 1b in Italian patients with Porphyria cutanea tarda

BACKGROUND

A strong association between sporadic porphyria cutanea tarda and chronic hepatitis C virus infection was recently described in Italy, France and Spain.

AIMS

To explore whether hepatitis C virus genotype plays a role in porphyria cutanea tarda complicating chronic hepatitis C.

PATIENTS

Forty-seven hepatitis C virus-positive porphyria cutanea tarda patients and a control group of 45 patients of similar age with hepatitis C virus-associated chronic liver disease.

METHODS

Comparison of frequency of hepatitis C virus genotypes in the two groups and in relation to the age of patients, hepatic histopathology and with the presence of other factors potentially able to trigger porphyria cutanea tarda.

RESULTS

A single genotype, hepatitis C virus 1b, was found to be present in nearly 90% of porphyria cutanea tarda-associated chronic liver disease, significantly exceeding the frequency of the same genotype in the control group (p = 0.0001). The presence of hepatitis C virus 1b was not related to the age of patients or disease severity as evaluated by hepatic histopathology.

CONCLUSIONS

Hepatitis C virus-associated chronic hepatitis found in the majority of Italian patients with porphyria cutanea tarda is usually sustained by hepatitis C virus genotype 1b. This viral strain might have a direct pathogenic role in inducing porphyria cutanea tarda or could increase the susceptibility of patients of other triggering factors such as iron overload or alcohol abuse.

The expression of uridine diphosphate glucuronosyltransferase gene is a major determinant of bilirubin level in heterozygous beta-thalassaemia and in glucose-6-phosphate dehydrogenase deficiency

We evaluated the effect of Gilbert's syndrome, the most common defect of bilirubin conjugation, on the bilirubin levels of subjects with inherited haematological disorders which cause increased bilirubin production. 57 patients heterozygous for beta-thalassaemia, 21 with G6PD deficiency and 44 controls were examined by typing the TATA-box in the promoter of the gene uridine diphosphate glucuronosyltransferase 1A. Nearly 80% of patients with increased bilirubin levels were heterozygous or homozygous for the UGT1A TA(7) variant associated with Gilbert's syndrome. These findings indicate that Gilbert's syndrome accounts for a large proportion of the variability of bilirubin levels in beta-thalassaemia and G6PD deficiency.

Genetic heterogeneity in heterocellular hereditary persistence of fetal hemoglobin

A large English pedigree in which heterocellular hereditary persistence of fetal hemoglobin (HPFH) segregates is described. beta-globin cluster deletions and gamma gene promoter mutations associated with HPFH have been excluded. Of particular importance in this pedigree is the absence of any cosegregating hemoglobinopathy, thus allowing observation of the segregation pattern of this form of HPFH without the complicating effect of a beta-globin gene mutation. Information gained in this study confirms that the extent of elevation of hemoglobin (Hb) F and F cells varies between affected individuals. There are one example of incomplete penetrance and three examples of father-to-son transmission, thus excluding X-linked inheritance. Consistent with previous reports, the most likely mode of inheritance is autosomal codominant. Linkage studies using a beta-globin cluster microsatellite show no evidence of linkage to this chromosomal region implicating the presence of trans-acting regulatory factor(s). We have recently mapped one such locus to the chromosome 6q region in a very large Asian-Indian pedigree. Linkage to chromosome 6q in the English pedigree was excluded, thus indicating the presence of genetic heterogeneity in heterocellular HPFH.

Prevalence and clinical significance of hepatitis G virus infection in adult beta-thalassaemia major patients

The risk of polytransfused patients for hepatitis C virus (HCV) infection is likely to extend to another recently identified member of the Flaviviridae, hepatitis G virus (HGV). We investigated the prevalence of HGV in 40 adult Italian patients with transfusion-dependent thalassaemia and evaluated the clinical significance of HGV infection. HGV-RNA was detected in 9/40 patients (22.5%). HGV infection was significantly associated with HCV viraemia (P = 0.0012), with all patients positive for HGV being also viraemic for HCV. Overall, the clinical picture of patients with HCV/HGV co-infection was not different from that of patients with isolated HCV. However, patients co-infected with both viruses had lower values of alanine-transferase (P = 0.035) and a lower titre of HCV viraemia (P = 0.042) in the absence of other evident factors which could influence the clinical expression of HCV infection. In conclusion, HGV is highly prevalent among Italian polytransfused patients. No evidence of a clinically significant pathogenic role for HGV in liver disease could be found in these patients. In a subset of cases a possible interference of HGV with HCV infection was observed.

Liver iron influences the response to interferon alpha therapy in chronic hepatitis C

OBJECTIVE

To define whether there is any relation between the iron status of patients with hepatitis C virus (HCV) chronic liver disease and their response to interferon therapy.

DESIGN

To evaluate the long-term response to 1 year of interferon therapy with addition of phlebotomies after 3 months of treatment if at that time alanine aminotransferase (ALT) had not normalized in a group of patients with HCV-positive chronic liver disease whose iron status had been characterized.

SETTING

A northern Italian hospital.

PARTICIPANTS

Fifty-eight anti-HCV-positive patients (four HCV-RNA negative) with biopsy proven chronic hepatitis and no evidence of iron overload as indicated by normal transferrin saturation at the time of enrollment in the study.

INTERVENTION

Three times a week intramuscular injection of alpha interferon 3 MU for 1 year with addition of phlebotomies (350 ml/week) till iron depletion if after 3 months of interferon therapy ALT had not normalized.

RESULTS

A long-term response was observed in 19 of the 52 patients who completed the treatment, four HCV-RNA negative and 15 positive. The four RNA-negative and seven of the 15 RNA-positive long-term responders had been treated with interferon alone, and the other eight also with phlebotomies. At univariate analysis only HCV genotype, gamma-glutamyltranspeptidase and liver iron concentration were significantly associated with response whereas sinusoidal iron deposition was of borderline significance. No association was found with sex, age, duration of disease, histology, Knodell score, transferrin saturation %, serum ferritin, hepatocytic iron score, and portal iron score. HCV-RNA serum levels, measured in 29 patients, did not correlate with response. At multivariate analysis liver iron concentration was still significant and one unit reduction of liver iron concentration (natural logarithm transformed) was associated with 2.95 odds ratio of response.

CONCLUSION

These results indicate that iron in the liver is more closely related to response to interferon than the other variables considered, including HCV characteristics.

Diffusion of HCV through peritoneal membrane in HCV positive patients treated with continuous ambulatory peritoneal dialysis

PURPOSE OF THE STUDY

We evaluated the presence of HCV in the peritoneal effluents of viraemic patients treated with continuous ambulatory peritoneal dialysis (CAPD) to evaluate the risk of transmitting the infection with this procedure.

PROCEDURE

Fifteen of 81 CAPD patients (18.5%) had anti-HCV antibodies and eight were viraemic. At the beginning of CAPD two of the viraemic patients had ascites with a clinical picture of chronic active hepatitis and cirrhosis. Peritoneal dialysates were collected after an overnight exchange with 1.36% glucose and after a 4-h exchange with 3.86% glucose. Fluids from the overnight exchange were spun to obtain a cellular pellet and the supernatant 100-fold concentrated.

RESULTS

No viral genome could be detected in unconcentrated samples and in cellular pellets, while HCV-RNA at low titre was detected in concentrated dialysates from the two patients with active liver disease.

CONCLUSIONS

Our findings confirm that HCV may be present in the CAPD effluent of some patients; however, the titre of virus in the effluent was extremely low, at the limit of detection of the PCR assay. Peritoneal fluids originating from patients with HCV associated severe liver disease may be a potential source of infection.

Hepatitis G virus infection in hemodialysis patients

The increased risk of hemodialysis patients for infections sustained by hepatitis viruses is likely to extend to a newly discovered parenterally transmitted virus, HGBV-C/HGV, able to cause acute and chronic hepatitis. The aim of this study was to assess the prevalence and clinical relevance of this infection in Italian hemodialysis patients. Nineteen of 100 patients (19%) on maintenance hemodialysis were viremic for HGBV-C/HGV, and all of them were infected with a HGV-like genotype. Eight of these patients were coinfected by hepatitis B or hepatitis C viruses. A clinical picture of chronic hepatitis was not appreciable in patients with isolated HGV infection and the presence of HGV did not appear to modify the clinical course of hepatitis B and hepatitis C infections.

No association between genetic hemochromatosis and alpha1-antitrypsin deficiency

Genetic hemochromatosis and alpha1-antitrypsin (AAT) deficiency are frequent in white populations. Conflicting data on the association of the two conditions and on the severity of the disease in those in whom these disorders coexist have emerged from analyses of small numbers of patients. To determine if the frequency of AAT deficiency is increased in genetic hemochromatosis, we characterized this protein by isoelectric focusing and DNA analysis in 115 Italian patients with the disease and 290 controls. The frequency of AAT deficiency in patients with genetic hemochromatosis was similar to that in controls (10% and 9%, respectively). The prevalence of cirrhosis in patients with genetic hemochromatosis with MM phenotype was 53%, compared with 58% in those with non-MM phenotype; that of hepatocellular carcinoma, occurring only in cirrhotic patients, was 22% and 28%, respectively. In conclusion, the frequency of AAT deficiency was not increased in our large series of Italian patients with genetic hemochromatosis. Patients in whom the two defects coexisted did not appear to have a more severe disease, but the limited number of subjects with non-MM phenotype does not allow a conclusive evaluation of clinical differences between them and patients with genetic hemochromatosis with MM phenotype.