PubMed Health⌕ Search

Biomedical subjects

V Dessi

Publications and source records attributed to V Dessi.

14 recordsLinked to original sources
PubMed2002

Abnormal mRNA splicing resulting from consensus sequence splicing mutations of ATP7B.

More than 200 Wilson disease (WD) disease-causing mutations have been defined to date. Missense mutations are largely prevalent while splice-site mutations are limited in number. Most reside in the splice donor or acceptor sites and only a minority are detected in splicing consensus sequences. Furthermore, only a few splicing mutations have been studied at the RNA level to date. In this study, using the RT-PCR method we performed the molecular characterization of four consensus splice-site mutations identified by DNA analysis in patients with WD. One of them, previously described 1707+3insT, occurred at position 3 in the donor splice site of intron 4, while the other three, 2122-8T>G, 2866-6T>G, and 3061-12T>A, are novel and occurred in the acceptor splice sites of introns 7, 12, and 13, respectively. Analysis revealed a prevalently abnormal splicing in the samples carrying the mutations compared to the normal controls. Comparison of RNA splicing with normal controls in liver and lymphocytes further suggests that abnormal splicing of the WD gene is also present and differentially regulated in normal tissues. The results produced in this study strongly suggest that DNA mutations residing in the consensus sequence of WD gene splice sites result in the WD phenotype by interfering with the production of the normal WD protein. Further studies are necessary to better quantify the amount of different transcripts produced by these mutations, and establish their correlation with the disease phenotype.

Adenosine Triphosphatases↗
PubMed1999

Molecular characterization of wilson disease in the Sardinian population--evidence of a founder effect.

Wilson disease (WD) in the Sardinian population has an approximate incidence of 1:7,000 live births. Mutation analysis of the WD gene in this population reported in our previous articles led us to the characterization of two common mutations and a group of 13 rare mutations accounting for the molecular defect of 8.5, 7.9, and 15.1% of the WD chromosomes. However, molecular analysis of the WD chromosomes containing the most common haplotype, which accounts for 60.5% of the WD chromosomes, failed to define the disease-causing mutation. In this study, we characterized the promoter and the 5' UTR of the WD gene sequence and carried out a mutation analysis in this DNA region from patients with the most common haplotype. The promoter is contained in a GC-rich island and shows a TATA and a CAAT consensus sequence as well as potential binding sites for transcription factors and metal response elements. In all the analyzed 92 chromosomes with this haplotype, we detected a single mutation consisting of a 15-nt deletion from position -441 to position -427 relative to the translation start site. Expression assays demonstrated a 75% reduction in the transcriptional activity of the mutated sequence compared to the normal control. By adding this mutation to those that have been already characterized, we have now defined the molecular defect in 92% of the WD chromosomes in Sardinians. The high frequency, the expected prevention by preclinical diagnosis and early treatment of the devastating effect of WD on the nervous system and liver tissue, and the feasibility to detect most of molecular defects by DNA analysis indicate that WD in the Sardinian population should be added to the list of diseases currently detected by newborn screening.

5' Untranslated Regions↗
PubMed1999

Mutation analysis in patients of Mediterranean descent with Wilson disease: identification of 19 novel mutations.

In this study, we report further results of mutation analysis of the ATP7B gene in Wilson disease (WD) patients of Mediterranean origin. A total of 136 WD chromosomes, 73 of which were of Italian, 43 of Turkish, 18 of Sardinian, and two of Spanish origin, were analysed and the mutation characterised in 84.5% of them. We found 50 different mutations of which 19 are novel, including three nonsense, one frameshift, and 15 missense mutations. The mutations detected were rare and mostly found in the compound heterozygous state together with other mutations and only rarely in homozygosity. Most of these mutations lie in the transmembrane and ATP binding loop regions. These data expand our knowledge of both the structure-function relationships of the WD protein and the molecular pathology of WD, thus improving our capability of prevention and genetic counselling.

Adenosine Triphosphatases↗
PubMed1998

Early and severe neurological features in a Wilson disease patient compound heterozygous for two frameshift mutations.

UNLABELLED: We describe a patient with Wilson disease who presented at 11 years of age with neurological symptoms and subsequent rapid progression of neurological impairment but absent hepatic manifestations. Molecular analysis showed compound heterozygosity for two frameshift mutations, 2299insC and 214delAT, which most likely result in an absent or inactive protein product. Mutation-phenotypic analysis indicates that this genotype does not explain the severe phenotype, suggesting the presence of modifying factors. CONCLUSION: Wilson disease may present even in childhood or adolescence with neurological abnormalities in the absence of hepatic manifestations.

Child↗
PubMed1995

Molecular pathology and haplotype analysis of Wilson disease in Mediterranean populations.

We analyzed mutations and defined the chromosomal haplotype in 127 patients and Mediterranean descent who were affected by Wilson disease (WD), 39 Sardinians, 49 Italians, 33 Turks, and 6 Albanians. Haplotypes were derived by use of the microsatellite markers D13S301, D13S296, D13S297, and D13S298, which are linked to the WD locus. There were five common haplotypes in Sardinians, three in Italians, and two in Turks, which accounted for 85%, 32%, and 30% of the WD chromosomes, respectively. We identified 16 novel mutations: 8 frameshifts, 7 missense mutations, and 1 splicing defect. In addition, we detected the previously described mutations: 2302insC, 3404delC, Arg1320ter, Gly944-Ser, and His1070Gin. Of the new mutations detected. two, the 1515insT on haplotype I and 2464delC on haplotype XVI, accounted for 6% and 13%, respectively, of the mutations in WD chromosomes in the Sardinian population. Mutations H1070Q, 2302insC, and 2533delA represented 13%, 8%, and 8%, respectively, of the mutations in WD chromosomes in other Mediterranean populations. The remaining mutations were rare and limited to one or two patients from different populations. Thus, WD results from some frequent mutations and many rare defects.

Albania↗
PubMed1993

Application of the MAILA technique to the study of human anti-HLA monoclonal antibody specificity.

The monoclonal antibody-specific immobilization of lymphocyte antigens (MAILA) assay was developed to detect antibodies present in human alloantisera against antigens of different major histocompatibility complex loci, particularly of class II specificity. The MAILA assay has been used in our laboratory to the determination of the type of HLA molecule recognized by human monoclonal antibodies 91C2 (anti-A2 + 28), 34F11 (anti-DQ1), and 2A2 (anti-DQ1 + 4 + short DQ7), using well characterized monomorphic as well as polymorphic murine monoclonals for the specific immobilization of HLA molecules. Results obtained show that the MAILA assay is also a valuable tool for the determination of specific human MHC locus products recognized by human monoclonal antibodies.

Animals↗
PubMed1993

A human monoclonal antibody reacting against HLA-DQ1-, DQ4-, and a subset of DQ7-bearing cells.

Human mAb 2A2 recognizes an epitope present in the HLA-DQ1 + 4 specifications and also on several DQ7-positive cells. We have investigated the extra reactions of this monoclonal reagent on a wider panel of DQ1-, DQ4-negative/DQ7-positive B-cell lines. The results obtained support the existence of two subtypes of the HLA-DQ7 specificity on the basis of their reactivity with human mAb 2A2; the DQ7/2A2-positive variant has been found in 12 of 29 BCLs positive for the DR11 antigen, and in four of eight BCLs bearing DR4-DQ7 haplotypes. It has also been detected in the DR12-positive cells assayed and in several unusual DR/DQ7 combinations not commonly found in Caucasoid populations, including the DR13-DwHAG and DR14-Dw16 haplotypes. Results from competition binding assays between 2A2 and well-characterized murine anti-DQ polymorphic mAbs suggest that the epitope recognized by human mAb 2A2 on DQ1- or DQ4-bearing haplotypes is located on the DQ beta chains of such specificities, being amino acid residues 54-55, the potential binding site of antibody 2A2, whereas the binding site on DQ7 antigens cannot be explained on the basis of known amino acid sequences.

Amino Acid Sequence↗
PubMed1990

Characterization of three human monoclonal antibodies specific for polymorphic class I and class II HLA antigens.

Three human monoclonal antibodies were derived from a single polytransfused patient awaiting renal transplantation. In microcitotoxicity assays, the patient's serum displayed strong positive reactions against greater than 90% of a panel of cells representing the known HLA specificities. The donor's peripheral blood lymphocytes were infected with Epstein-Barr virus, cloned, and supernatants of the virus transformed cultures were screened for the presence of IgG antilymphocyte reactivity utilizing an enzyme-linked immunosorbent assay method. Positive cultures were recloned and fused with the human-mouse heteromyeloma SHM. Supernatants from three clones were selected for alloreactivity and characterized by indirect immunofluorescent staining and fluoroactivated cell sorter analysis on homozygous typing cells, including those from the Tenth International Histocompatibility Workshop core panel and on cell lines derived from selected families. Data obtained demonstrate that two human monoclonal antibodies have DQw1 specificity, one of them being reactive against several DQw7-positive cell lines, while one monoclonal antibody is specific for the A2 + A28 class I MHC antigens. Anti-DQw1 antibodies were of different light-chain subtypes.

Antibodies, Monoclonal↗
PubMed1989

Use of bispecific hybrid antibodies for the development of a homogeneous enzyme immunoassay.

Hybrid bispecific monoclonal antibodies reacting with carcinoembryonal antigen (CEA) and with the E. coli enzyme beta-galactosidase (GZ) were produced by fusion of hybridomas or chemical linkage of half-antibodies. Since the original anti-GZ antibody used in these experiments was capable of protecting GZ from thermal denaturation, it was possible, by hybridizing it with two different non-competitive anti-CEA antibodies, to design a homogeneous enzyme immunoassay for quantitation of CEA. In fact, a mathematical analysis of the reaction indicates that, under appropriate concentrations of the reactants, circular complexes can be formed which contain the two hybrid antibodies, the GZ enzyme and the CEA antigen. The stability of these complexes can be expected to be substantially greater than that of the more labile CEA-free GZ-antibody complexes, prompting a significant increase in the amount of enzyme molecules which are bound to antibody and are consequently protected from thermal denaturation. These expectations were supported by experimental results: under appropriate conditions, heat-resistant enzyme activity was indeed proportional to concentration of CEA in the range up to 75 ng/ml. As predicted by theory, however, in the presence of excess CEA - in fact at CEA concentrations which are higher than those of possible clinical relevance - circular complexes tended to open up, leading to a marked prozone effect.

Antibodies, Monoclonal↗
PubMed1986

Selective reversal of H-2-linked genetic unresponsiveness to lysozymes. II. Alteration in the T helper/T suppressor balance, owing to gene(s) linked to Ir-2, leads to responsiveness in BALB.B.

Immune responsiveness to lysozyme in H-2b mice is under the control of H-2-linked Ir genes, with T suppressor (Ts) cells playing a dominant role in strains such as C57BL/6 (B6), C57BL/10 and A.BY. However, non-H-2-genes were found to be capable of specific reversal of the effect of the H-2-linked genes in responsiveness to chicken lysozyme (HEL), but not to human lysozyme (HUL). Therefore, studies were performed to identify any lesion in the suppressor circuit in BALB.B. It was known that HUL-induced suppressor cells could cross-suppress the anti-HEL response in B10.Q mice, which are responsive to HEL but nonresponsive to HUL. Similarly, BALB.B Ts cells were able to suppress the anti-HEL response, using as T helper (Th) source a T cell line (BB-1), derived from HEL-primed BALB.B periaortic and inguinal lymph node cells. A protocol designed to examine the in vivo suppression by the use of HUL-induced suppressor cells also demonstrated a significant suppression of the anti-HEL response. Since the suppressive circuitry seemed intact in the BALB.B, the possibility was examined that a step in T-B cell collaboration was more efficient in this strain than in the B6 nonresponder. With a B6-derived HEL-specific T cell line, BO1H, the B cell and antigen-presenting (B/APC) populations from B6 required addition of concanavalin A supernatant for anti-HEL antibody formation, whereas BALB.B B/APC were capable of responding to HEL in culture without the addition of concanavalin A supernatant. In agreement with this finding, when B/APC cell populations from BALB.B and B6 were compared for their extent of anti-HEL responsiveness, as measured with BB-1 Th cells, BALB.B B/APC populations responded significantly higher than B6 populations when the responses were activated by picogram/nanogram amounts of HEL. The response level of (BALB.B X B6)F1 B/APC measured in the same assay resembled that of B6. However, when HEL was used at the microgram level, both B6 and BALB.B strains responded equivalently. The above data are consistent with the expression of the reversing non-H-2 Ir gene(s) resulting from the balance of antigen presentation to Th and Ts cells in the H-2b mouse. In the B6, processing and handling of antigen may be inefficient in activating response-enhancing Th, and more effective in triggering Ts cells, while the reverse may be true for the BALB.B.

Animals↗
PubMed1986

Difference in sensitivity to cyclosporine in vitro of human alloreactive lines and clones.

The effectiveness of cyclosporine (CsA) as immunosuppressive agent in human kidney graft rejection is well established. However, in spite of efforts to maintain optimal plasma levels, a fraction of transplanted patients undergo rejection episodes and/or irreversible chronic rejection. This suggests that immunosuppression by CsA cannot control the alloreactive response if there is a high degree of histoincompatibility for HLA or non-HLA antigens, or it has little effect on the "high responder" patient. Both possibilities are difficult to test in the human system. A third hypothesis, the existence of individual CsA resistance, was tested by evaluating the in vitro inhibitory activity of CsA on alloreactive T cell lines from several individuals. A different degree of in vitro sensitivity to the drug was observed among alloreactive lines generated from different individuals and among clones obtained from the same bulk line. The variability at the individual level and at the clonal level may account for the onset of CsA-resistant rejection assuming that in vivo a positive selection in the presence of the drug occurs and allows for the resistant clones, if present, to dominate the sensitive ones.

Cell Line↗