Defective targeting of hemojuvelin to plasma membrane is a common pathogenetic mechanism in juvenile hemochromatosis

Hemojuvelin (HJV) positively modulates the iron regulator hepcidin, and its mutations are the major cause of juvenile hemochromatosis (JH), a recessive disease leading to iron overload. Defective HJV reduces hepcidin up-regulation both in humans and in Hjv-deficient mice. To investigate the JH pathogenesis and the functional properties of human HJV we studied the biosynthesis and maturation of 6 HJV pathogenic mutants in HeLa and HepG2 cells. We show that proteolytic processing is defective in mutants F170S, W191C, and G320V, but not in G99V and C119F. Moreover, we show that mutants G99V and C119F are targeted to the cell surface, while F170S, W191C, G320V, and R326X (lacking the glycosilphosphatidylinositol [GPI] anchor) are mainly retained in the endoplasmic reticulum, although all mutants are released as soluble forms (s-HJV) in a proportion that is modulated by iron supplementation. Membrane HJV (m-HJV) is mainly composed of the cleaved protein, and its level is increased by iron in wild-type (WT) mice but not in the mutants. Altogether, the data demonstrate that the loss of HJV membrane export is central to the pathogenesis of JH, and that HJV cleavage is essential for the export. The results support a dual function for s- and m-HJV in iron deficiency and overload, respectively.

RNA silencing of the mitochondrial ABCB7 transporter in HeLa cells causes an iron-deficient phenotype with mitochondrial iron overload

X-linked sideroblastic anemia with ataxia (XLSA/A) is caused by defects of the transporter ABCB7 and is characterized by mitochondrial iron deposition and excess of protoporphyrin in erythroid cells. We describe ABCB7 silencing in HeLa cells by performing sequential transfections with siRNAs. The phenotype of the ABCB7-deficient cells was characterized by a strong reduction in proliferation rate that was not rescued by iron supplementation, by evident signs of iron deficiency, and by a large approximately 6-fold increase of iron accumulation in the mitochondria that was poorly available to mitochondrial ferritin. The cells showed an increase of protoporphyrin IX, a higher sensitivity to H2O2 toxicity, and a reduced activity of mitochondrial superoxide dismutase 2 (SOD2), while the activity of mitochondrial enzymes, such as citrate synthase or succinate dehydrogenase, and ATP content were not decreased. In contrast, aconitase activity, particularly that of the cytosolic, IRP1 form, was reduced. The results support the hypothesis that ABCB7 is involved in the transfer of iron from mitochondria to cytosol, and in the maturation of cytosolic Fe/S enzymes. In addition, the results indicate that anemia in XLSA/A is caused by the accumulation of iron in a form that is not readily usable for heme synthesis.

Microelectronic DNA chip for hereditary hyperferritinemia cataract syndrome, a model for large-scale analysis of disorders of iron metabolism

Hereditary hyperferritinemia cataract syndrome (HHCS) is caused by mutations in the regulatory iron responsive element (IRE) in the 5'UTR of the L-ferritin transcript that reduce binding affinity to the iron regulatory proteins (IRPs) and lead to a constitutive upregulation of the protein in tissue and serum. Twenty-nine mutations have been reported within the L-ferritin (FTL) IRE sequence, 21 of which were available to us. In addition, we included in this study three new mutations. Thus, we analyzed 24 mutations spanning over a DNA stretch of 48 nucleotides, including four deletions 2-29 nucleotides long and 20 substitutions, seven of which were conservative transversions. With this unique experimental model we developed a microchip diagnostic platform for identifying known molecular defects in the L-ferritin IRE structure with a microelectronic array approach, which we optimized after studying the effects of various parameters. The system enables electronic deposition of biotinylated amplicons to selected pads. Under optimized conditions, no cross-hybridization was found, even for mutations that affected the same or adjacent nucleotide positions. The same cartridge could be serially hybridized with all the 24 reporter probe sets, which allowed correct genotyping right up until the end of the analysis. Extensive validation on 200 samples in a blinded fashion gave total concordance of results. This pilot study represents a first step toward developing a diagnostic microchip for large-scale analyses for epidemiological studies and screening of mutations associated with iron disorders.

Characterization of the l-ferritin variant 460InsA responsible of a hereditary ferritinopathy disorder

Hereditary ferritinopathies are dominant inherited movement disorders associated with extensive alterations of the l-ferritin C-terminus peptide caused by nucleotide insertions in l-ferritin gene (FTL). We describe the characterization of the most common variant, produced by the 460InsA mutations and here named Ln1. The recombinant Ln1 assembled into 24-mer ferritin shells with low efficiency, however, it was able to form heteropolymers that showed a reduced capacity to incorporate iron in vitro. The Ln1 expressed in HeLa cells formed hybrid ferritins, with the endogenous H and L chains, and caused an iron excess phenotype. Ferritin inactivation and faster degradation in Ln1 transfectants concurred in increasing iron availability, which was probably responsible for the higher sensitivity to H(2)O(2) toxicity and higher level of oxidized proteins. The findings suggest that the pathogenic effects of Ln1 expression are more likely due to deregulation of cellular iron homeostasis rather than to protein conformational problems.

Association between the arginine vasopressin 1a receptor (AVPR1a) gene and autism in a family-based study: mediation by socialization skills

We examined three microsatellites in the arginine vasopressin 1a receptor gene (AVPR1a), two in the promoter region (RS1 and RS3) and an intronic microsatellite (AVR), for association with autism as well as scores on the Vineland Adaptive Behavior Scale (VABS), the Autism Diagnostic Interview-Revised (ADI-R) and the Autism Diagnostic Observation Scale-Generic (ADOS-G), measures that are widely used to diagnose autism spectrum disorders. We tested for association between the AVPR1a microsatellites and autism in 116 families (128 probands diagnosed with the ADI-R and ADOS-G using a family-based association test (UNPHASED)). Testing each individual microsatellite showed significant transmission disequilibrium in these families with the AVR intronic microsatellite (UNPHASED: LRS=11.46, global P-value=0.009, df=3). Haplotype analysis of three microsatellites also showed significant association (LRS=144.94, df=103, global P=0.004). Additionally, significant association is observed between these three microsatellite haplotypes and the VABS scores (P=0.009), with the ADI-R (P=0.009) and the ADOS-G (P=0.0000765) diagnoses of autistic disorder versus pervasive developmental disorder-not otherwise specified (PDD-NOS) that were available for 47 of these probands. This is the third consecutive report of an association between the AVPR1a gene and autism spectrum disorders and in the current study a third microsatellite is shown to be associated with autism spectrum disorders as well as haplotypes consisting of all three markers. Importantly, the association appears to be mainly mediated by the role of the AVPR1a gene in shaping socialization skills, similar to its role in lower vertebrates.Molecular Psychiatry (2006) 11, 488-494. doi:10.1038/sj.mp.4001812; published online 7 March 2006.

Flow cytometry evaluation of erythroid dysplasia in patients with myelodysplastic syndrome

Erythroid dysplasia is the pathologic hallmark of myelodysplastic syndromes (MDS). To develop a quantitative flow-cytometry approach to its evaluation, we analyzed the expression of CD71, CD105, cytosolic H-ferritin (HF), cytosolic L-ferritin (LF) and mitochondrial ferritin (MtF) in erythroblasts from 104 MDS patients, 69 pathologic control patients and 19 healthy subjects. Six-parameter, 4-color flow cytometry was employed, and data were expressed as mean fluorescence intensity. Compared with pathologic and healthy controls, MDS patients had higher expression of HF (P < 0.001) and CD105 (P < 0.001), and lower expression of CD71 (P < 0.001). MtF was specifically detected in MDS with ringed sideroblasts, and there was a close relationship between its expression and Prussian blue staining (r = 0.89, P < 0.001). In vitro cultures of myelodysplastic hematopoietic progenitors showed that both HF and MtF were expressed at a very early stage of erythroid differentiation, and that MtF expression is specifically related to mitochondrial iron loading. A classification function based on expression levels of HF, CD71 and CD105 allowed us to correctly classify > 95% of MDS patients. This flow-cytometry approach provides an accurate quantitative evaluation of erythroid dysplasia and allows a reliable diagnosis of sideroblastic anemia, and may therefore be a useful tool in the work-up of patients with MDS.

Recombinant human hepcidin expressed in Escherichia coli isolates as an iron containing protein

Hepcidin is a small peptide that acts as a regulator of systemic iron homeostasis. To study some of its functional properties, a synthetic cDNA for the minimal, 20-amino-acid, form of human hepcidin was cloned into different constructs for expression in Escherichia coli. The fusion ferritin-hepcidin produced molecules retaining most of ferritin structural and functional properties, including ferroxidase and iron incorporation activities. However, it showed spectroscopic properties compatible with the presence of iron-sulfur complexes on the hepcidin moiety, which was buried into protein cavity. Similar complexes were reconstituted by in vitro incubation of the iron-free protein with iron and sulfide salts. Two other unrelated fusion products were constructed, which, when expressed in E. coli, formed insoluble aggregates retaining a large proportion of total bacterial iron. Analysis of the solubilized preparations showed them to contain iron-sulfur complexes. We concluded that the cysteine-rich hepcidin acts as an iron-sequestering molecule during expression in E. coli. This may have implications for the biological functions of this key protein of iron metabolism.

Neuroferritinopathy: a neurodegenerative disorder associated with L-ferritin mutation

Neuroferritinopathy is a dominantly inherited movement disorder characterized by deposition of iron and ferritin in the brain, normal or low serum ferritin levels, and highly variable clinical features. The disease, also named dominant adult-onset basal ganglia disease, is associated with a nucleotide insertion that modifies the last 22 amino acids of the ferritin L-chain. A similar dominant movement disorder in a French family was associated with a nucleotide insertion that modifies the last nine amino acids of the same molecule. Both disorders show ferritin and iron precipitates in the basal ganglia of the brain. Here we present the structural aspects of the two mutations, as well studies on cellular models aimed at understanding the molecular basis of the disorder. The results indicate that the mutations affect protein folding and stability, and that the expression of one of the two variant ferritins increases intracellular iron availability and sensitivity to oxidative damage.

Unique Iron Binding and Oxidation Properties of Human Mitochondrial Ferritin: A Comparative Analysis with Human H-chain Ferritin

Ferritins are ubiquitous iron mineralizing and storage proteins that play an important role in iron homeostasis. Although excess iron is stored in the cytoplasm, most of the metabolically active iron is processed in the mitochondria of the cell. Little is known about how these organelles regulate iron homeostasis and toxicity. The recently discovered human mitochondrial ferritin (MtF), unlike other mammalian ferritins, is a homopolymer of 24 subunits that has a high degree of sequence homology with human H-chain ferritin (HuHF). Parallel experiments with MtF and HuHF reported here reveal striking differences in their iron oxidation and hydrolysis chemistry despite their similar diFe ferroxidase centers. In contrast to HuHF, MtF does not regenerate its ferroxidase activity after oxidation of its initial complement of Fe(II) and generally has considerably slower ferroxidation and mineralization activities as well. MtF exhibits sigmoidal kinetics of mineralization more characteristic of an L-chain than an H-chain ferritin. Site-directed mutagenesis reveals that serine 144, a residue situated near the ferroxidase center in MtF but absent from HuHF, is one player in this impairment of activity. Additionally only one-half of the 24 ferroxidase centers of MtF are functional, further contributing to its lower activity. Stopped-flow absorption spectrometry of Fe(II) oxidation by O(2) in MtF shows the formation of a transient diiron(III) mu-peroxo species (lambda(max) = 650 nm) as observed in HuHF. Also, as for HuHF, minimal hydroxyl radical is produced during the oxidative deposition of iron in MtF using O(2) as the oxidant. However, the 2Fe(II) + H(2)O(2) detoxification reaction found in HuHF does not occur in MtF. The structural differences and the physiological implications of the unique iron oxidation properties of MtF are discussed in light of these results.

Mitochondrial ferritin

A novel ferritin type specifically targeted to mitochondria has been recently found in human and mouse. It is structurally and functionally similar to the cytosolic ferritins, well-characterized molecules found in most living systems which are designed to store and detoxify cellular iron. Cytosolic ferritins in mammals are ubiquitous while mitochondrial ferritin expression is restricted mainly to the testis, neuronal cells and islets of Langherans. In addition, it is abundant in the iron-loaded mitochondria of erythroblasts of patients with sideroblastic anaemia. The characterization of recombinant and transfected mitochondrial ferritin indicated that this protein has a role in protecting mitochondria from iron-induced damage. These data suggest that it is an interesting tool to study the iron metabolism in this organelle. In addition, it may be useful for the diagnosis of myelodysplastic syndromes and in protecting mitochondria from the toxic effects of excess iron.

Monolayer-functionalized microfluidics devices for optical sensing of acidity

This paper describes the integration of opto-chemosensors in microfluidics networks. Our technique exploits the internal surface of the network as a platform to build a sensing system by coating the surface with a self-assembled monolayer and subsequently binding a fluorescent sensing molecule to the monolayer. Fluorescent molecules were used that can switch between a fluorescent and a non-fluorescent state, depending on the acidity of the surrounding solution. Two systems were investigated. The first employs surface confinement of a Rhodamine B dye in a glass micro channel that serves as a molecular switch in organic solutions. Upon rinsing the micro channels with acidic or basic solutions it was possible to switch between the fluorescent and non-fluorescent forms reversibly. Moreover, this system could be used to monitor the mixing of two solutions of different acidity along the micro channel. To widen the scope of optical sensing in micro channels an Oregon Green dye derivative was immobilized, which functions as a sensing molecule for pH differences in aqueous solutions. In this case, a hybrid system was used consisting of a glass slide and PDMS channels. The fluorescence intensity was found to be directly correlated to the pH of the solution in contact, indicating the possibility of using such a system as a pH sensor. These systems allow real-time measurements and can be easily implemented in micro- and nanofluidics systems thus enabling analysis of extremely small sample volumes in a fast and reproducible manner.

Ferroportin gene silencing induces iron retention and enhances ferritin synthesis in human macrophages

Missense mutations in the ferroportin gene (SLC11A3) result in haemochromatosis type 4 [HFE4, Online Mendelian Inheritance in Man (OMIM) reference 606069] or ferroportin disease, an autosomal dominant disorder characterized by predominantly reticuloendothelial iron accumulation. To verify whether HFE4 is caused by defective iron recycling because of loss of functionality of ferroportin, we down-regulated SLC11A gene expression in human macrophages by using small interfering RNAs (siRNAs). Transfection experiments with ferroportin siRNAs resulted in a marked reduction (about two-thirds on average) in ferroportin mRNA levels as detected by quantitative real time polymerase chain reaction. When macrophages were grown in medium supplemented with iron, cells transfected with siRNAs displayed three- to eightfold increases in staining intensities following Perls reaction. These macrophages also showed significant increases in H-ferritin content. The observation that ferroportin mRNA down-regulation to levels compatible with haplo-insufficiency causes increased iron retention and H-ferritin synthesis in cultured macrophages has important implications. First, this indicates that ferroportin levels must be finely regulated in order to maintain cellular iron homeostasis, and that both copies of SLC11A3 must function efficiently to prevent iron accumulation. Second, this observation supports the hypothesis that reticuloendothelial iron overload in patients with ferroportin disease is caused by loss-of-function mutations in the SLC11A3 gene that mainly impair macrophage iron recycling.

The expression of human mitochondrial ferritin rescues respiratory function in frataxin-deficient yeast

Mitochondrial ferritin (MtF) is structurally and functionally similar to the cytosolic ferritins, molecules designed to store and detoxify cellular iron. MtF expression in human and mouse is restricted to the testis and few tissues, and it is abundant in the erythroblasts of patients with sideroblastic anemia, where it is thought to protect the mitochondria from the damage caused by iron loading. Mitochondria iron overload occurs also in cells deficient in frataxin, a mitochondrial protein involved in iron handling and implicated in Friedreich ataxia. We expressed human MtF in frataxin-deficient yeast cells, a well-characterized model of mitochondrial iron overload and oxidative damage. The human MtF precursor was efficiently imported by yeast mitochondria and processed to functional ferritin that actively sequestered iron in the organelle. MtF expression rescued the respiratory deficiency caused by the loss of frataxin protecting the activity of iron-sulfur enzymes and enabling frataxin-deficient cells to grow on non-fermentable carbon sources. Furthermore, MtF expression prevented the development of mitochondrial iron overload, preserved mitochondrial DNA integrity and increased cell resistance to H2O2. The data show that MtF can substitute for most frataxin functions in yeast, suggesting that frataxin is directly involved in mitochondrial iron-binding and detoxification.

Crystal structure and biochemical properties of the human mitochondrial ferritin and its mutant Ser144Ala

Mitochondrial ferritin is a recently identified protein precursor encoded by an intronless gene. It is specifically taken up by the mitochondria and processed to a mature protein that assembles into functional ferritin shells. The full mature recombinant protein and its S144A mutant were produced to study structural and functional properties. They yielded high quality crystals from Mg(II) solutions which diffracted up to 1.38 Angstrom resolution. The 3D structures of the two proteins resulted very similar to that of human H-ferritin, to which they have high level of sequence identity (approximately 80%). Metal-binding sites were identified in the native crystals and in those soaked in Mn(II) and Zn(II) solutions. The ferroxidase center binds binuclear iron at the sites A and B, and the structures showed that the A site was always fully occupied by Mg(II), Mn(II) or Zn(II), while the occupancy of the B site was variable. In addition, distinct Mg(II) and Zn(II)-binding sites were found in the 3-fold axes to block the hydrophilic channels. Other metal-binding sites, never observed before in H-ferritin, were found on the cavity surface near the ferroxidase center and near the 4-fold axes. Mitochondrial ferritin showed biochemical properties remarkably similar to those of human H-ferritin, except for the difficulty in renaturing to yield ferritin shells and for a reduced ( approximately 41%) rate in ferroxidase activity. This was partially rescued by the substitution of the bulkier Ser144 with Ala, which occurs in H-ferritin. The residue is exposed on a channel that connects the ferroxidase center with the cavity. The finding that the mutation increased both catalytic activity and the occupancy of the B site demonstrated that the channel is functionally important. In conclusion, the present data define the structure of human mitochondrial ferritin and provide new data on the iron pathways within the H-type ferritin shell.

C29G in the iron-responsive element of l-ferritin: a new mutation associated with hyperferritinemia-cataract

Hyperferritinemia-cataract syndrome (HHCS) is a dominant disorder characterized by high serum ferritin and early onset of bilateral cataract. The disorder is caused by mutations in the iron-responsive element (IRE) of l-ferritin, which disrupt the postranscriptional control of l-ferritin synthesis. Here, we report a new (C>G) mutation which affects base 29 in the loop (c.-169C>G), previously unrecognized as essential for the stem loop stability. The mutation was identified in two members of an Italian family. Computer modeling and electrophoretic mobility shift assay (EMSA) confirm a decreased affinity of the C29G IRE for IRPs control proteins.

Blotting analysis of native IRP1: a novel approach to distinguish the different forms of IRP1 in cells and tissues

Iron regulatory protein 1 (IRP1) is a bifunctional protein, which either has aconitase activity or binds to specific mRNA structures to regulate the expression of iron proteins. Using recombinant human IRP1, we found that the two functional forms are resolved by nondenaturing polyacrylamide gel electrophoresis and that they are distinguished from IRP1/RNA complexes. This allowed us to use specific antibodies to develop a blotting system that recognized the iron-free and iron-containing IRP1 forms in the soluble fraction and the RNA-bound IRP1 in the high-speed precipitate fraction of cell extracts. The system was used to study IRP1 in HeLa, K562 cells, and monocytes/macrophages before and after treatment with iron salts, iron chelators, or hydrogen peroxide, as well as in stomach and duodenum biopsies. The results showed that iron-bound aconitase IRP1 is by far the prevalent form in most cells and that the major effect of cellular iron modifications is a shift between free and RNA-bound IRP1. The fraction of RNA-bound IRP1 was highly variable among different cells and was often a minor one. Furthermore, blotting showed that electrophoretic mobility shift assay, as commonly used, tends to under-evaluate the amount of total IRP1 and to over-evaluate the actual RNA-binding activity of IRP1. In conclusion, blotting analysis of IRP1 is a new, useful, and convenient method to analyze the amount and conformations of the protein that reveals previously undetected differences in IRP1 compartmentalization among various cell types.

Analysis of the biologic functions of H- and L-ferritins in HeLa cells by transfection with siRNAs and cDNAs: evidence for a proliferative role of L-ferritin

We describe the use of small interfering RNAs (siRNAs) to down-regulate H- and L-ferritin levels in HeLa cells. siRNAs repressed H- and L-ferritin expression to about 20% to 25% of the background level in both stable and transient transfections. HeLa cells transfected with H- and L-ferritin cDNAs were analyzed in parallel to compare the effects of ferritin up- and down-regulation. We found that large modifications of L-ferritin levels did not affect iron availability in HeLa cells but positively affected cell proliferation rate in an iron-independent manner. The transient down-regulation of H-ferritin modified cellular iron availability and resistance to oxidative damage, as expected. In contrast, the stable suppression of H-ferritin in HeLa cell clones transfected with siRNAs did not increase cellular iron availability but made cells less resistant to iron supplementation and chelation. The results indicate that L-ferritin has no direct effects on cellular iron homeostasis in HeLa cells, while it has new, iron-unrelated functions. In addition, they suggest that H-ferritin function is to act as an iron buffer.

Identification of two novel mutations in the 5'-untranslated region of H-ferritin using denaturing high performance liquid chromatography scanning

BACKGROUND AND OBJECTIVES

Hereditary hyperferritinemia cataract syndrome is caused by mutations of the iron responsive elements (IREs) of L-ferritin mRNA. These alter the IRE structure and determine L-ferritin upregulation. IREs are located in 5'untranslated regions (5'UTR) of ferritin mRNAs. L-ferritin 5'UTR has been extensively studied and up to 21 different mutations have been identified. Only one mutation has been reported for H-ferritin 5'UTR; this mutation modified IRE structure and was apparently associated with high serum ferritin levels and iron overload.

DESIGN AND METHODS

To identify other mutations in H ferritin 5'UTR we developed a fast DNA scanning method based on denaturing high performance liquid chromatography (HPLC). Five artificial DNA mutants were produced in order to validate the analytical conditions of the system for the identification of all mutations by single runs at 68 degrees C. The system was used to screen 660 DNA samples from subjects with high serum ferritin levels.

RESULTS

Two abnormal patterns were identified carrying the mutations C20G and G34T. Structural data and the analysis of ferritin levels in red blood cells suggest that these mutations do not affect the functionality of the IRE.

INTERPRETATION AND CONCLUSIONS

This large and first population analysis indicates that mutations in the H-ferritin 5'UTR are rare and do not seem to contribute to hyperferritinemia or iron overload.

The Role of Autumn Infections in the Progression of Fire Blight Symptoms in Perennial Pear Branches

The role of autumn infections in the progression of fire blight (caused by Erwinia amylovora) symptoms in perennial pear branches was studied in orchard-grown trees in Israel. The extent of symptom progression and the final length of fire blight cankers in perennial branches were variably affected by the vigor of the trees and the season of infection. Following spring infections, when all trees supported active shoot growth, fire blight symptoms progressed more rapidly and to longer distances in trees that exhibited high vigor (i.e., with numerous annual shoots on most terminal branches) than in low-vigor trees (i.e., few or no annual shoots on terminal branches). Irrespective of the vigor of the trees, the progression of fire blight symptoms in perennial branches ceased between mid-May and mid-July, and only a small proportion (0 to 14.2%) of the infections had invaded main limbs or trunks of trees. Progression of fire blight symptoms following autumn infections was related to the preceding summer (August to No-vember) shoot regrowth: in trees in which the shoots did not restore their growth in the summer, the rate of symptom progression in perennial branches was higher in trees with a low vigor than in those with a high vigor, whereas for those with summer regrowth the relationship between rates of symptom expression was reversed. Irrespective of the vigor group and of whether there was summer regrowth, symptoms in perennial branches continued to progress through the winter until the following spring. Most of the autumn infections (50 to 78.5%) that developed in susceptible trees had invaded main limbs or trunks of trees. The results of this study indicate that factors related to host phenology and physiology, rather than factors related to environmental influences (such as temperature), govern the extent, rate, and duration of fire blight progression in perennial pear branches. Furthermore, it turned out that autumn infections play a substantial role in fire blight epidemiology in Israel.

New Considerations for Pruning in Management of Fire Blight in Pears

The efficacy of pruning infected pear tissues to combat fire blight (caused by Erwinia amylovora) was evaluated in two sets of experiments conducted during 1999 to 2001 in Israel. In the first set of two experiments, diseased tissues were removed soon after the observation of blossom infections. Pruning was effective in 0 to 50% of the treated trees, and resulted in complete eradication of E. amylovora. In the remaining trees, pruning not only did not result in eradication of the bacteria from the tree tissues, it made the situation worse, as the disease had invaded the main branches and limbs of a significantly larger proportion of pruned trees than of non-pruned ones, because of alteration of the physiological status of the host plant by pruning. In the five experiments of the second set, the efficacy of pruning fire blight infections on main branches and limbs was studied; the time of pruning varied among the experiments. Effectiveness of cutting and removing infected branches and limbs was linearly related to time of treatment: the efficacy of pruning improved significantly with lateness of the treatment. The best results were obtained when pruning was carried out while the trees were dormant, in December: none of these trees had a severely infected canopy the following spring. Based on the results obtained in this study, it was concluded that factors related to all three components of the disease triangle (i.e., pathogen, host, and environment), rather than only the actual presence of diseased tissues, should be taken into account in considering the need for cutting and removing fire blight-diseased tissues. Accordingly, recommendations for Israeli growers were revised and updated.

Short-term outcome of isolated and associated congenital heart defects in relation to antenatal ultrasound screening

OBJECTIVE

To investigate the outcome of fetuses affected by congenital heart defects (CHD), either detected or undetected at ultrasound screening, according to their complexity and severity.

DESIGN

The study group comprised 3633 malformed fetuses entered into the Eurofetus database of which 798 had CHD. We compared the short-term outcome in cases where a CHD was detected by ultrasound screening with that in cases where a CHD was not detected. Isolated and associated CHD (ICHD and ACHD) and the degree of severity of defects were considered separately. Outcome data included termination of pregnancy (TOP), intrauterine fetal death, neonatal death (< 6 days after birth), gestational age at diagnosis and at delivery, mode of delivery and birth weight.

RESULTS

Of the 798 fetuses with CHD, 595 had ICHD and 203 had ACHD. The diagnosis of an anomaly was made significantly earlier in ACHD cases. TOP was chosen in 28% of cases with a prenatal diagnosis of CHD, 20% for ICHD and 37% for ACHD (P < 0.001). The survival rate of antenatally diagnosed fetuses was lower in those with ACHD than in those with ICHD (P < 0.001) and lower for fetuses with antenatal diagnosis than with postnatal diagnosis (P < 0.001); this was due to significant differences in the complexity and severity of the defect. Premature delivery (< 32 weeks) was more frequent in fetuses in which an antenatal diagnosis of CHD had been made. Severe CHD were diagnosed earlier and were associated with a higher rate of TOP and spontaneous loss.

CONCLUSIONS

The severity of CHD has a positive influence on the sensitivity of screening but a negative influence on the outcome. CHD that are not diagnosed antenatally include a high proportion of benign malformations. This explains the apparent paradox of a poorer outcome in fetuses in which a CHD was detected prenatally compared to those fetuses in which the defect was undetected prenatally. However, prenatal diagnosis provides parents with the option of TOP or of preventive care in specialized centers.