Isolation and characterization of a novel transcript embedded within HIRA, a gene deleted in DiGeorge syndrome

We have isolated a few cDNAs from different human tissues, transcribed from the first intron of HIRA, a gene deleted in the DiGeorge syndrome. These cDNAs are produced by an intronic gene (22k48) which is transcribed by the HIRA opposite strand and is itself arranged in exons and subjected to alternative splicing. The longest continuum cDNA sequence we obtained is 3.6 kb long and contains 3 different exons and 2 introns. 22k48 cDNA is composed of several tandemly arranged repeated elements (Alu, LINEs, CAn) surrounding a unique sequence. In situ hybridization showed the presence of 22k48 RNA in the cytoplasm of CNS and PNS neurons. 22k48 RNA is able to bind cytoplasmic proteins in the range of 45 to 60 kDa. 22k48 is a new member of the small group of genes that are transcribed but not translated, and its haploinsufficiency could contribute to the pathogenesis of the DiGeorge syndrome.

Exclusion of the ninjurin gene as a candidate for hereditary sensory neuropathies type I and type II

Ninjurin is a protein that is up-regulated in Schwann cells and neurons after peripheral nerve injury. Its role in promoting nerve regeneration and its expression in sensory neurons of dorsal root ganglia, as well as the chromosomal localization of the ninjurin gene, makes this gene a candidate for hereditary sensory neuropathies (HSN). In the present report, the human ninjurin gene was analyzed in 17 unrelated patients with HSN type I, two patients with HSN type II, and 10 normal controls, by single strand conformation polymorphism and by direct sequencing. All three exons and splice junctions of the gene were investigated and no mutations were found in our sample of patients. Our results rule out a mutation in the translated region of the ninjurin gene as a cause of HSN type I and type II.

Screening of thyrotropin receptor mutations by fine-needle aspiration biopsy in autonomous functioning thyroid nodules in multinodular goiters

Multinodular goiter (MNG) is characterized by nodules of different size and function. Areas of increased function may emerge, appearing as single, or more frequently, multiple autonomously functioning thyroid nodules (AFTN). The molecular mechanism for the autonomous growth and function of these nodules has been related to mutations in the thyrotropin receptor (TSHR) that constitutively activate the adenylyl cyclase. We searched for mutations in a limited area of the TSHR gene, covering the major mutational hotspot, in 38 AFTNs found in 37 patients with MNGs. We used reverse transcriptase-polymerase chain reaction (RT-PCR) and restriction enzyme analysis of fine-needle aspiration biopsy (FNAB) samples to rapidly identify 4 of the more frequently occurring TSHR mutations: D619G, F631C, T632I and D633E. Mutations were identified in 5 nodules (1 D619G mutation and 4 T632I mutations). Subsequently, the entire transmembrane portion of the TSHR gene was sequenced in a random sample of 12 AFTN samples that were free of mutations by RT-PCR and restriction enzyme analysis. By direct sequencing we identified a new mutation, F666L, in the seventh transmembrane domain in a sample from 1 nodule. Analysis of FMA samples of AFTN is an effective approach to identify TSHR gene mutations because individual mutations may be associated with different growth and function in vitro, our approach might, allow correlation of a given mutation with the clinical behavior in vivo.

Mapping of the MYCL2 processed gene to Xq22-23 and identification of an additional L MYC-related sequence in Xq27.2

We report here the identification of a human genomic sequence from the q27.2 region of the X chromosome which shows a high homology to the L-MYC proto-oncogene. This sequence is not the MYCL2 homology, previously mapped to the long arm of the X chromosome at q22-qter by Morton et al., as we located the MYCL2-processed gene in Xq22-23, using a panel containing a combination of hybrid DNA carrying different portions of the human X chromosome. Based on computer analysis, the MYC-like sequence (MYCL3) is 98.2% identical to a portion of exon 3 of the MYCL1 gene and maps to the Xq27.2 region, between the DXS312 and DXS292 loci.

Genomic structure, promoter characterisation and mutational analysis of the S100A7 gene: exclusion of a candidate for familial psoriasis susceptibility

We have recently assigned a locus for familial psoriasis (PS) susceptibility to the region containing the epidermal differentiation complex gene cluster on chromosome 1q21. Gene S10OA7 maps within this cluster and is reported to be markedly over-expressed in the skin lesions of psoriatic patients. In order to analyse S100A7 as a candidate for PS susceptibility, we have determined its genomic structure regarding exon-intron boundaries and the transcription start site. The gene is organised in three exons and two introns, spanning 2.7 kb. The 5' flanking region contains AP1- and Sp1-binding motifs and a TATA box. We have performed functional assays by using the beta-galactosidase gene as a reporter and have confirmed that this region has strong promoter activity. To search for nucleotide variation within S100A7, we have designed a set of primers to amplify each exon and the gene promoter. Polymerase chain reaction products from 15 unrelated PS patients selected from 1q-linked pedigrees and 25 normal controls have been characterised by single-strand conformation polymorphism and direct sequencing techniques. These analyses have revealed the presence of two polymorphisms in the promoter region (-559G/A and -563 A/G), neither of which shows preferential association with the disease. Our results indicate that S100A7 can be excluded as a candidate for PS susceptibility.

Immunomagnetic isolation of human developing motor neurons

Human motor neuron (MN) isolation provides a critical tool to study neurophysiological properties and the effects of molecules of clinical relevance on isolated neurons. We developed an immunomagnetic separation technique based on specific MN antigen recognition for nerve growth factor receptor (p75-NGFR). We cultured an average of 250,000 cells from the anterior horns of a single cord (four specimens at postconception Weeks 6.0, 7.2, 8.0, and 8.3). At day 7 in vitro (DIV), choline acetyltransferase (ChAT) and/or p75-NGFR-expressing cells (MNs) represented 72 +/- 2% of the total growing cells. MNs survived for at least 4 weeks in biochemically defined medium. The immunomagnetic separation method has been demonstrated to be effective, reproducible, and quantitative for separation of MNs.

Structure and expression of the human ubiquitin fusion-degradation gene (UFD1L)

We report the genomic organization, RNA and protein expression patterns of the gene encoding for the human homolog of the yeast ubiquitin fusion-degradation protein-1 (UFD1L). This enzyme is involved in a ubiquitin-dependent proteolytic pathway (UFD), firstly described in yeast. The human UFD1L gene is organized into 12 exons ranging in size from 33 to 161 bp. Sequence analysis of the 5'-flanking region of the gene revealed a high GC content, multiple CCAAT-binding motifs, CREB, CFT, and AP-2 sites. RNA transcripts were detected in all tissues and cell lines examined, including thymus, thymocytes, T- and B-cells, fibroblasts, chorionic villi, and amniocytes. In Western blot, the UFD1L antibody demonstrated the presence of multiple protein isoforms in all the tested tissues. Expression profile and promoter characteristics suggest UFD1L is a housekeeping gene with implications in the pathogenesis of DiGeorge/velo-cardio-facial syndrome, due to 22q11.2 deletions.

Human NRD convertase: a highly conserved metalloendopeptidase expressed at specific sites during development and in adult tissues

We report the cloning of the human homologue of the rat metalloprotease N-arginine dibasic convertase (NRD convertase). This endopeptidase is responsible for the processing, at the Arg-Lys dibasic site on the N-terminal side of the arginine residue, of propeptides and proproteins. Comparisons of the human and rat full-length cDNAs show similarity and identity of 94 and 91%, respectively. In humans NRD convertase is predominantly expressed in heart, skeletal muscle, and testis. We have also studied the expression of this gene in mouse at various developmental stages and found that the neural tissue is the almost exclusive site of expression in early development (between E 10.5 and E 16.5). To gain information about the possibility that defects in this gene are linked to inherited neuromuscular disorders, we determined the chromosomal location of the human NRD convertase gene by FISH analysis, showing that the gene resides at 1p32.2.

mRNA distribution in adult human brain of GRIN2B, a N-methyl-D-aspartate (NMDA) receptor subunit

The expression of the N-methyl-D-aspartate (NMDA) receptor subunit NR2B/epsilon2 (GRIN2B) in the human adult brain was assayed by in situ hybridisation, by using a specific cRNA probe. The full length GRIN2B cDNA was cloned and sequenced. It showed a 90% nucleotide conservation when compared to the rodent homologue. GRIN2B gene is expressed at high levels in the fronto-parieto-temporal cortex and hippocampus pyramidal cells and, at a lower extent, in the basal ganglia (amygdala and striatum). The cerebellar granule cells does not show any mRNA expression. The non-ubiquitous anatomical distribution of the GRIN2B mRNA in the central nervous system suggests that the gene could be involved in specific functions pertaining to the expressing cell groups.

[Natriuretic peptides and the heart. Critical review and application]

This paper deals with a literature survey on natriuretic peptides (NP) and their clinical use in prognostic stratification and therapy of arterial hypertension and cardiac failure. After a brief historical introduction, the phylogenesis of NP is analyzed and the reasons of their preservation in the evolution are emphasized. The biochemistry of the NP is then treated, and the structure, synthesis, mechanism of cellular action and systems of regulation are analyzed. Subsequently, the authors have analyzed the physiology of the NP as well as their hemodynamic and biohumoral effects and actions on the central nervous system. A literature review on the significance of NP in arterial hypertension, on their usefulness as indicators of damage and on their therapeutic practice is then made. In particular, the possible future applications in the prevention of atherosclerotic damage are analyzed. The significance of NP and of their metabolites in heart failure and the prognostic implication of these peptides particularly in ischemic heart failure are then discussed. The most important papers on this topic are described. Finally the studies on the use of NP in the therapy of heart failure are analyzed and a guide on research of this topic is defined.

[Anticoagulation and electrical cardioversion of chronic atrial fibrillation: proposal for an abbreviated protocol]

BACKGROUND

Several weeks of prophylactic anticoagulation are routinely prescribed before and after electrical cardioversion of atrial fibrillation. Recent studies have supported the use of transesophageal echocardiography to guide early cardioversion: patients in whom no thrombus is observed are treated with heparin followed by one month of warfarin therapy after the procedure. This kind of treatment requires hospital admission during heparin infusion, because of the need for monitoring partial thromboplastin time.

AIM OF THE STUDY

To evaluate if a short at-home treatment (three days) with warfarin is sufficient to reach a good level of anticoagulation, in order to permit safe electrical cardioversion in day-hospital for patients who show no thrombi on transesophageal echocardiography.

METHODS

One hundred twenty-four patients with atrial fibrillation, who were candidates for cardioversion, were treated with warfarin: 10 mg the first and second day, 5 mg the third day in group A patients (n = 79); 15 mg the first day, 10 mg the second and third day in group B patients (n = 45). On the fourth day, INR value was measured and if it was < 2, warfarin therapy was prolonged until patients reached a good level of anticoagulation. Transesophageal echocardiography was performed when the INR was > or = 2, and patients were cardioverted with DC shock if there were no thrombi. The patients were discharged on the same day of the procedure, and warfarin therapy was continued for 4 weeks there-after. If a thrombus was detected, patients repeated transesophageal echocardiography after 6 weeks of warfarin therapy, and were cardioverted if the thrombus disappeared. Otherwise, cardioversion was deferred and they received prolonged warfarin treatment. If there was poor visualization of the left atrial appendage, patients received conventional warfarin therapy for 3 weeks before and 4 weeks after electrical cardioversion.

RESULTS

Mean INR value after three days of warfarin treatment was 2.41 in group A patients and 3.02 in group B patients. Twenty-one patients from group A and 3 patients from group B required anticoagulant therapy for a mean of 3.3 and 5.1 days, respectively, before reaching a good level of anticoagulation (INR value > or = 2). Eight patients reverted spontaneously to sinus rhythm before transesophageal echocardiography. Eighteen thrombi (15.5%) were identified on the transesophageal echocardiography, all of which were in the left atrial appendage. In 11 cases, thrombus disappeared after 6 weeks of warfarin therapy. In 7 patients (6%), the atrial appendage was not sufficiently visualized. Electrical cardioversion was performed on 109 patients and was successful in 88 (80.7%). None of them experienced a clinical thromboembolic event.

CONCLUSIONS

In the majority of patients in atrial fibrillation, a short at-home warfarin treatment is sufficient to reach a good level of anticoagulation in order to permit safe electrical cardioversion in a day-hospital situation. Larger initial doses can achieve even better results. This treatment algorithm minimizes the anticoagulation period, hospital stay, overall duration of atrial fibrillation and the time required for the mechanical function of the left atrium to return.

[Evaluation of a registration card for logging electrocardiographic records into standard personal computers]

BACKGROUND

The MS200 Cardioscope, from MRT Micro as., Norway, is a 12 channel ECG card to be directly inserted into a standard personal computer (PC). The standard ISA Bus compatible half length card comes with a set of 10 cables with electrodes and the software for recording, displaying and saving ECG signals. The system is supplied with DOS or Windows software. The goal of the present work was to evaluate the affordability and usability of the MS200 in a clinical setting.

MATERIALS AND METHODS

We tested the 1.5 DOS version of the software. In 30 patients with various cardiac diseases the ECG signal has been recorded with MS200 and with standard Hellige CardioSmart equipment. The saved ECGs were recalled and printed using an Epson Stylus 800 ink-jet printer. Two cardiologists reviewed the recordings for a looking at output quality, amplitude and speed precision, artifacts, etc.

RESULTS

1) Installation: the card has proven to be totally compatible with the hardware; no changes in default settings had to be made. 2) Usage: the screens are clear; the commands and menus are intuitive and easy to use. Due to the boot-strap and software loading procedures and, most important, off-line printing, the time needed to obtain a complete ECG printout has been longer than that of the reference machine. 3) Archiving and retrieval of ECG: the ECG curves can be saved in original or compressed form: selecting the latter, the noise and non-ECG information is filtered away and the space consumption on disk is reduced: on average, 20 Kb are needed for 10 seconds of signal. The MS200 can be run on a Local Area Network and is prepared for integrating with an existing informative system: we are currently testing the system in this scenery. 4) MS200 includes options for on-line diagnosis, a technology we have not tested in the present work. 5) The only setting allowed for printing full pages is letter size (A4): the quality of printouts is good, with a resolution of 180 DPI.

CONCLUSIONS

In conclusion, the MS200 system seems reliable and safe. In the configuration we tested, it cannot substitute a dedicated ECG equipment: from this point of view, a smaller PCMCIA-type card with a battery-operated notebook PC will be more suitable for clinical uses. Nevertheless, the possibility to log and track ECG records, integrated into the department informative system, may provide a valuable tool for improving access to medical information.

Expression study of survival motor neuron gene in human fetal tissues

In order to investigate the spinal muscular atrophy (SMA) disease processes, the expression of the survival motor neuron gene (SMN) has been analyzed in human fetal tissues using RT-PCR and in situ hybridization. These studies allowed the detection of SMN RNA in all the examined tissues, with no significant variation between different developmental stages. In particular, SMN mRNA was detected in spinal cord (dorsal and ventral portions), skeletal muscle, lung, heart, kidney, liver, and spleen. Moreover, RT-PCR studies demonstrated that the expression pattern of SMN isoforms was similar to that observed in adult tissues. The present data confirm a housekeeping role for the SMN protein and may have implications on the search for early therapeutic strategies.

[Pseudoaneurysm of the left ventricle after mitral valve replacement. Diagnosis 6 years after the intervention]

We present a case of left ventricular pseudoaneurysm diagnosed by chance 6 years after a second surgical intervention on the mitral valve (replacement with a St. Jude prosthesis). A combination of cross sectional and color-Doppler studies led to the correct diagnosis. A transesophageal echocardiographic investigation did not provide further information, while the diagnosis was confirmed by computed tomography with contrast agent. A retrospective analysis of previous examinations revealed that the pseudoaneurysm developed shortly after the mitral valve replacement, remaining stable over the years. The patient was clinically asymptomatic, the size of the pseudoaneurysm did not increase during a 2 years followup, and we decided to follow a conservative treatment.

SMT3A, a human homologue of the S. cerevisiae SMT3 gene, maps to chromosome 21qter and defines a novel gene family

cDNA selection was used to isolate coding sequences from cosmids mapping to the gene-rich telomeric region of human chromosome 21q. A novel cDNA, termed SMT3A, was isolated and mapped between the loci PFKL and D21S171, about 2.2 Mb proximal to the telomere. The predicted protein of 103 amino acids appears to be a homologue of the Saccharomyces cerevisiae SMT3 protein, whose gene was previously isolated as a suppressor of mutations in the MIF2 gene. The yeast MIF2 gene encodes an essential centromeric protein and shows homology to mammalian CENP-C, an integral component of active kinetochores. SMT3A was found to be highly homologous to two other recently isolated human genes, suggesting the presence of a new gene family. Homologous sequences were also found in protozoa, metazoa, and plants. Moreover, all predicted proteins show significant homology to ubiquitin. The proposed role of yeast SMT3 as centromeric protein and the strong evolutionary conservation of the SMT3A gene suggest an involvement of the encoded protein in the function and/or structure of the eukaryotic kinetochore.

UFD1L, a developmentally expressed ubiquitination gene, is deleted in CATCH 22 syndrome

The CATCH 22 acronym outlines the main clinical features of 22q11.2 deletions (cardiac defects, abnormal facies, thymic hypoplasia, cleft palate and hypocalcemia), usually found in DiGeorge (DGS) and velo-cardio-facial (VCFS) syndromes. Hemizygosity of this region may also be the cause of over 100 different clinical signs. The CATCH 22 locus maps within a 1.5 Mb region, which encompasses several genes. However, no single defect in 22q11.2 hemizygous patients can be ascribed to any gene so far isolated from the critical region of deletion. We have identified a gene in the CATCH 22 critical region, whose functional features and tissue-specific expression suggest a distinct role in embryogenesis. This gene, UFD1L, encodes the human homolog of the yeast ubiquitin fusion degradation 1 protein (UFD1p), involved in the degradation of ubiquitin fusion proteins. Cloning and characterization of the murine homolog (Ufd1l) showed it to be expressed during embryogenesis in the eyes and in the linear ear primordia. These data suggest that the proteolytic pathway that recognizes ubiquitin fusion proteins for degradation is conserved in vertebrates and that the UFD1L gene hemizygosity is the cause of some of the CATCH 22-associated developmental defects.

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.

Prediction of myotonic dystrophy clinical severity based on the number of intragenic [CTG]n trinucleotide repeats

We carried out a genotype-phenotype correlation study, based on clinical findings in 465 patients with myotonic dystrophy (DM), in order to assess [CTG] repeat number as a predictive test of disease severity. Our analysis showed that the DM subtypes defined by strict clinical criteria fall into three different classes with a log-normal distribution. This distribution is useful in predicting the probability of specific DM phenotypes based on triplet [CTG] number. This study demonstrates that measurement of triplet expansions in patients' lymphocyte DNA is highly valuable and accurate for prognostic assessment.

cDNA characterization and chromosomal mapping of two human homologues of the Drosophila dishevelled polarity gene

The Drosophila dishevelled gene (dsh) encodes a secreted glycoprotein, which regulates cell proliferation, acting as a transducer molecule for developmental processes, including segmentation and neuroblast specification. We have isolated and characterized cDNA clones from two different human dsh-homologous genes, designated as DVL-1 and DVL-3. DVL-1 and DVL-3 putative protein products show 64% amino acid identity. The DVL-1 product is 50% identical to dsh and 92% to a murine dsh homologue (Dvl-1). Both human DVL genes are widely expressed in fetal and adult tissues, including brain, lung, kidney, skeletal muscle and heart. DVL-1 locus maps to chromosome 1p36 and DVL-3 to chromosome 3q27. DVL-1 locus on chromosome 1 corresponds to the murine syntenic region where Dvl-1 is located. DVL-1 and DVL-3 are members of a human dsh-like gene family, which is probably involved in human development. Although the precise role of these genes in embryogenesis is only conjectural at present, the structural and evolutionary characteristics suggest that mutations at their loci may be involved in neural and heart developmental defects.

Human homologue sequences to the Drosophila dishevelled segment-polarity gene are deleted in the DiGeorge syndrome

DiGeorge syndrome (DGS) is a developmental defect of some of the neural crest derivatives. Most DGS patients show haploinsufficiency due to interstitial deletions of the proximal long arm of chromosome 22. Deletions of 22q11 have also been reported with patients with the velocardio-facial syndrome and familial conotruncal heart defects. It has been suggested that the wide phenotype spectrum associated with 22q11 monosomy is a consequence of contiguous-gene deletions. We report the isolation of human cDNAs homologous to the Drosophila dishevelled (dsh) segment-polarity gene. Sequences homologous to the 3' UTR of these transcripts (DVL-22) were positioned within the DGS critical region and were found to be deleted in DGS patients. Human DVL mRNAs are expressed in several fetal and adult tissues, including the thymus and, at high levels, the heart. Two transcripts, 3.2 and 5kb, were detected, in northern blot analysis, with different expression patterns in the surveyed tissues when different cDNAs were used. The isolated cDNAs exhibit high amino acid homology with the mouse and Xenopus Dvl-1 gene, the only other vertebrate dsh homologues so far isolated. The pivotal role of dsh in fly development suggests an analogous key function in vertebrate embryogenesis of its homologue genes. Since DGS may be due to perturbation of differentiation mechanisms at decisive embryological stages, a Dsh-like gene in the small-region overlap (SRO) might be a candidate for the pathogenesis of this disorder.