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L Luzzatto

Publications and source records attributed to L Luzzatto.

At least 181 records · Page 10Linked to original sources
PubMed1985

Heterogeneity of T-cell beta-chain gene rearrangements in human leukaemias and lymphomas.

The state of T-cell receptor beta-chain gene rearrangement in human T-cell leukaemias has been analysed. All forms of leukaemia tested (T-CLL, ALL, PLL, Sezary syndrome and ATL) exhibit rearrangements of C beta genes confirming the clonality of these neoplasias. However we find no evidence for common gene rearrangements nor for restricted rearrangement patterns within this type of neoplasia. We find evidence of T-cells with C beta 1 and C beta 2 rearrangements, sometimes associated with Igh JH rearrangements, but several cases of T-cell leukaemia with a marker inversion of chromosome 14 (q11;q32) do not have Igh JH rearrangements. The results suggest that TCR beta gene rearrangement occurs early in T-cell ontogeny but that this rearrangement is most often irrelevant to leukaemogenesis.

Cell Line↗
PubMed1985

Tissue-specific levels of human glucose-6-phosphate dehydrogenase correlate with methylation of specific sites at the 3' end of the gene.

Glucose-6-phosphate dehydrogenase (G6PD) is a ubiquitous enzyme that supplies the cell with NADPH required for a variety of reductive reactions and biosynthetic processes. Therefore, the gene G6PD, located in mammals on the X chromosome, that specifies G6PD can be regarded as a typical housekeeping gene. We have investigated the expression of human G6PD in eight different fetal and adult tissues by determining the level of enzyme activity, the level of G6PD mRNA, and the methylation pattern of the 3' end of the gene, for which we have nucleic acid probes. By combining sequence information with results of Southern blot analysis of DNA samples digested with the methylation-sensitive restriction enzyme Hpa II, we have identified five specific sites that are unmethylated in all tissues examined, a number of sites that are uniformly methylated, and a number of sites that are sometimes methylated. A subset of Hpa II sites, designated on our restriction map as H37-H55, exhibit positive correlation between degree of methylation, level of mRNA, and level of G6PD activity. A comparison of these methylation patterns with those we previously have observed in the G6PD gene on the inactive X chromosome [Toniolo, D., D'Urso, M., Martini, G., Persico, M.G., Tufano, V., Battistuzzi, G. & Luzzatto, L. (1984) EMBO J. 3, 1987-1995] indicates that different sites are associated with X-inactivation and with the regulation of G6PD on the active X chromosome. We conclude that this housekeeping gene is subject to tissue-specific transcriptional regulation, which in turn correlates with methylation of specific sites located at and near the 3' end of the gene.

Gene Expression Regulation↗
PubMed1985

Prolymphocytic leukemia of B cell type: rearranged immunoglobulin (Ig) genes with defective Ig production.

An unusual case of prolymphocytic leukemia of the B cell type (B-PLL) in a 79-year-old patient is reported. The clinical and cytomorphological features of the disease were typical of B-PLL, but membrane and cytoplasmic immunoglobulins (Ig) could not be demonstrated by immunofluorescence techniques; 3% to 4% of the cells were shown to have IgG kappa in the cytoplasm by a more sensitive immunoperoxidase method. The cells were unreactive with a panel of monoclonal antibodies against T cell antigens but they were positive with B cell lineage reagents: FMC4, anti-HLA-Dr determinants; FMC7, which reacts with most B-PLL; anti-B1 and anti-B4, which react with most B cell leukemias. Analysis of Ig genes at the DNA level demonstrated that both heavy-chain alleles and one kappa chain allele were rearranged, confirming that the patient's cells were of B lineage. Chromosome analysis revealed a consistent abnormality, t(17;21)(p11;p11), in all cells and, in addition, a 14q+ marker in 10% of the cells. This study highlights the value of DNA analysis techniques for the characterization of neoplastic B cells. The low rate of expression of Ig genes, despite their rearrangement, suggests that a specific transcriptional or posttranscriptional defect must exist in these cells.

Aged↗
PubMed1984

Specific methylation pattern at the 3' end of the human housekeeping gene for glucose 6-phosphate dehydrogenase.

During detailed restriction enzyme mapping of the human X-linked gene Gd, specifying the enzyme glucose 6-phosphate dehydrogenase (G6PD), we have observed the presence, over a 14-kb DNA region spanning across the 3' end of the G6PD transcript, of a large number of methylatable sites. These include 60 HpaII sites, 13 SmaI sites, 22 AvaI sites and 46 HhaI sites. In male leukocyte DNA the majority of HpaII sites are resistant to digestion, indicating that they are in the Cm5CGG form. However, a few sites are found reproducibly unmethylated in 24 samples analyzed. By double and triple digestions we have mapped five unmethylated sites, four of which are within the gene transcript and one distal to the end of transcription. We have also identified a number of sites which are fully methylated, whereas for others the methylation status could not be positively assessed. Thus, in a housekeeping gene expressed in leukocytes, the 3' end is extensively methylated, but some specific sites are unmethylated. In female leukocyte DNA, we found that all sites methylated in males were also methylated. However, of the five sites that are unmethylated in males two are partly methylated in females. This additional site-specific methylation involves approximately 50% of the female leukocyte DNA, and we show evidence that it is associated with the inactive X-chromosome.

Base Sequence↗
PubMed1984

Cytological mapping of the human glucose-6-phosphate dehydrogenase gene distal to the fragile-X site suggests a high rate of meiotic recombination across this site.

The human gene for glucose-6-phosphate dehydrogenase (G6PD) has been subregionally mapped to band Xq28 by segregation analysis in rodent-human somatic cell hybrids [Pai, G. S., Sprinkel, J. A., Do, T. T., Mareni, C. E. & Migeon, B. R. (1980) Proc. Natl. Acad. Sci. USA 77, 2810-2813]. We have previously reported a common type of X-linked mental retardation associated with an inducible fragile site at Xq27-Xq28 segregates in a close linkage relationship with a G6PD variant, but the relative position of G6PD with respect to the fragile site has not yet been established. This fragile-X syndrome has been shown to be closely linked also to a Taq I restriction fragment length polymorphism detected by a cDNA probe for factor IX, and the latter locus has been mapped to the subtelomeric region Xq26-Xq28 [Camerino, G., Mattei, M. G., Mattei, G. F., Jaye, B. & Mandel, J. L. (1983) Nature (London) 306, 701-704]. The in situ hybridization studies reported here provide strong evidence that G6PD is located on the Xq telomeric fragment distal to the fragile site. These observations and the well-established knowledge that the genes for Deutan and Protan colorblindness are closely linked to G6PD, but segregate independently of factor IX deficiency, suggest that the fragile site associated with this type of X-linked mental retardation occurs in a region prone to high frequency of meiotic recombination.

Animals↗
PubMed1984

Congenital dyserythropoietic anaemia type II associated with a new type of G6PD deficiency (G6PD Gabrovizza).

A 6-year-old boy with chronic haemolytic anaemia was found to have glucose 6-phosphate dehydrogenase (G6PD) deficiency and the morphological, ultrastructural and serological features of congenital dyserythropoietic anaemia (CDA) type II. The patient's mother was heterozygous for G6PD deficiency. G6PD from the patient's red cells, upon partial purification and full characterization, was found to be a new variant designated G6PD Gabrovizza. We conclude that two distinct genetic abnormalities coexisted in this patient. We suggest that CDA type II may become clinically more expressed when another abnormality of the erythrocytes coexists.

Anemia, Dyserythropoietic, Congenital↗
PubMed1984

DNA rearrangements of immunoglobulin genes correlate with phenotypic markers in B-cell malignancies.

We have investigated the configuration of immunoglobulin (Ig) genes in leukaemic cells in 17 patients with B-cell leukaemias (11 chronic lymphocytic leukaemias (B-CLL); 4 prolymphocytic leukaemias (B-PLL), and two hairy cell leukaemias (HCL)). In addition we studied four patients with T chronic lymphocytic leukaemia (T-CLL); four patients with acute leukaemia (3 acute lymphoblastic leukaemias (ALL), and 1 mixed acute leukaemia (M.AL)); and six patients with chronic granulocytic leukaemias in blastic crisis (CGL.BC). The heavy chain genes (H) were analysed by using probes for the constant region of the mu chains (C mu) and for the joining region (JH). The light chain genes were analysed by using probes for the constant region of the kappa (C kappa) and lambda (C lambda) chains. We have found rearranged Ig genes in all cases of B-CLL, B-PLL and HCL, but in none of the patients with T-CLL. In one case of HCL, both mu genes were deleted, indicating that in this case the class switch has taken place. In four out of six cases with either ALL or lymphoid CGL.BC and in one case of M.AL, an Ig gene rearrangement was also found. No rearrangement was detected in two cases of myeloid CGL.BC. When the combination of rearrangement versus germ-line configuration was considered, a variety of patterns emerge, but in no case did we find a L chain gene rearranged without at least one H chain gene being rearranged as well. Whereas in the majority of cases of B-CLL only one H chain gene is rearranged, in nearly all cases of B-PLL both H chain genes are rearranged. By systematic analysis of restriction fragment sizes of rearranged genes, we have established that a large number of different variable regions for the H chain (VH) are involved in Ig gene rearrangement in B-cell malignancies. Our data confirm that testing for Ig gene rearrangement may be the most sensitive and specific test for identifying leukaemic cells of B lineage.

B-Lymphocytes↗
PubMed1984

Two populations of erythroid cell progenitors in paroxysmal nocturnal hemoglobinuria.

We have grown erythroid cell colonies from two patients with paroxysmal nocturnal hemoglobinuria (PNH). At 11 to 13 days, individual bursts were picked and incubated for 24 hours with 3H-leucine in order to label total cell protein (mainly hemoglobin). After appropriate washing, each burst was subjected to a miniaturized acidified serum test, and lysis was measured by the release of radioactivity. In bursts from normal controls, lysis was 19% +/- 13% SD. By contrast, of 58 bursts from PNH patients, 14 had lysis similar to that of controls (mean 15.4% +/- 10.6%), while 44 had lysis ranging from 42.2% to 85.8% (mean 70.3% +/- 10.4%). Colonies sensitive to acidified serum were acetylcholinesterase (AchE) negative, whereas normal colonies were AchE-positive. Thus, based on two independent criteria, a dual population of erythroid burst-forming units (BFU-E) can be demonstrated in PNH. These data confirm directly the somatic mutation model of the pathogenesis of PNH, and by these methods the relative sizes of the normal and the PNH cell populations can be measured at the level of the erythroid cell precursors.

Acetylcholinesterase↗
PubMed1984

Partial purification and characterization of the messenger RNA for human glucose-6-phosphate dehydrogenase.

Glucose-6-phosphate dehydrogenase (G6PD) is a household enzyme that accounts, in many cells, for about 0.03% of cellular protein. We have developed an assay for G6PD-specific mRNA based on in vitro translation of RNA from human fibroblasts and immunoprecipitation of the translation products with an anti-G6PD antiserum. By making use of this assay, G6PD mRNA has been purified 50 to 100-fold in three steps. We estimate that the mRNA encoding G6PD constitutes less than 0.02% of total poly(A)+ RNA in human fibroblasts. The size of the G6PD mRNA has been established in denaturing conditions as being in the range between 2800 and 3200 nucleotides. This has been confirmed by Northern blot analysis. Since the G6PD coding sequence is estimated to be about 1491 nucleotides, the G6PD mRNA has long untranslated sequences, most of which is at the 3' end and which may be heterogeneous in length. The sequence of the last 608 nucleotides of this mRNA has been determined.

Cells, Cultured↗
PubMed1983

Tropical medicine: recent advances in malaria and other protozoal diseases.

Two recent developments in the field of trypanosomiasis and malaria are presented: 1) A novel mode of gene expression has been discovered in trypanosomes which enables the parasite to change its surface antigenicity with each new wave of parasitaemia, thus making an effective host response impossible. 2) The possibility to cultivate Plasmodium falciparum in vitro allows studies on the interaction of parasites and red cells, on drug resistance and on surface antigens.- Research in tropical diseases has given important contributions to biology and medicine in general. Basic research on the other hand is necessary to fight successfully tropical disease which are still common and often fatal.

Antigens, Surface↗
PubMed1983

Thalassemia.

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Gene Expression Regulation↗
PubMed1983

Genetic variation in the host and adaptive phenomena in Plasmodium falciparum infection.

The in vitro culture of Plasmodium falciparum, after synchronization, lends itself well to an analysis of the asexual schizogonic cycle. We have found in this system that DNA synthesis and RNA synthesis are associated mainly with the trophozoite stage, with the latter peaking slightly ahead of the former. Distinctive patterns of protein synthesis are seen at serial times along the cycle, with a number of 'stage-specific' bands identifiable on SDS gels. The fate of the infection can be influenced by the genotype of the host cell. Thus, glucose-6-phosphate dehydrogenase (G6PD)-deficient erythrocytes are invaded normally, but maturation of intracellular parasites is delayed and impaired. However, the parasites that do develop will then have a normal behaviour in their next rounds in G6PD-deficient cells, suggesting that an adaptive change has taken place. These results fit well with the relative protection against P. falciparum in vivo of girls heterozygous for G6PD deficiency but not of hemizygous G6PD-deficient boys.

Animals↗
PubMed1983

Regulation of glucose 6-phosphate dehydrogenase expression in CHO-human fibroblast somatic cell hybrids.

Human--hamster somatic cell hybrids have been obtained by fusion of a CHO line (NA31) doubly deficient in hypoxanthine guanine phosphoribosyltransferase and glucose 6-phosphate dehydrogenase (G6PD) with normal G6PD(+) human fibroblasts. Analysis of NA31 extracts has revealed that, although G6PD activity is nearly absent, significant activity can be detected with 2-deoxyglucose 6-phosphate as substrate, so that the mutant and normal forms of the enzyme can both be easily detected. The cell hybrids obtained express human G6PD. The human G6PD subunits are distributed in homodimeric molecules as well as in human--hamster heterodimeric molecules. However, whereas the amount of hamster G6PD subunits present in the hybrid is similar to that in the hamster parental cells, the amount of human G6PD subunits is decreased by 3- to 10-fold when compared to the human parental cell. These results indicate that either the expression of the G6PD gene or the stability of the gene product is altered in the hybrid. By mutagenesis and selection in diamide (a substance that oxidizes intracellular glutathione), we have isolated a clone with a 3- to 5-fold increase in human G6PD activity. This derivative may have an increased rate of expression of the human G6PD structural gene.

Animals↗
PubMed1983

Familial erythrocytosis with over-production of erythropoietin.

A family is described in which the father and son had erythrocytosis associated with a normal Hb oxygen affinity. Growth of erythroid colonies in vitro (BFU-E) exhibited normal erythropoietin dependence. In the son there was an enlarged erythroid precursor compartment, while the father (who had been treated by busulphan) showed marked reduction of circulating BFU-Es. Serum erythropoietin (Epo), estimated by radio-immunoassay, was 96 miu/ml in the son and 360 miu/ml in the father (normal 25, SD 6, n = 46). We conclude that erythrocytosis in this family is due to a genetically determined hyper-production of Epo. The finding in the father of a high Hb level associated with increased Epo and decreased BFU-Es might support the hypothesis that red cell mass is regulated by Epo at the level of bone marrow CFU-Es rather than BFU-Es.

Adult↗
PubMed1982

Pyruvate kinase deficiency: characterization of two new genetic variants.

Pyruvate kinase (PK) has been purified from the red blood cells of two sisters who had suffered severe chronic non-spherocytic haemolytic anaemia since infancy, and of one patient who had haemolytic anaemia during pregnancy. The two sisters showed remarkable clinical improvement following splenectomy. The enzyme from their red cells was found to exhibit low activity (about 25% of normal) in crude haemolysates, low affinity for the substrate, phosphoenol pyruvate (PEP), and high sensitivity to fructose-1,6-diphosphate (FDP) activation. This PK differs from previously reported variants and it is provisionally designated PK 'Torre Annunziata'. The enzyme from the other patient had near-normal activity in crude haemolysates, slight changes in kinetics with respect to the substrate, PEP, and with respect to the effects of FDP, ATP and pH, and a markedly reduced thermostability. This PK also differs from previously reported variants and it is provisionally designated PK 'Torre del Greco'. During the course of this study an improved method for purification of PK using Cibacron blue sepharose has been developed.

Adult↗