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Biomedical subjects

A Villegas

Publications and source records attributed to A Villegas.

At least 37 records · Page 2Linked to original sources
PubMed2000

A new polymorphim (G->A) in the psizeta1 globin gene.

BACKGROUND AND OBJECTIVES: a-globin cluster polymorphisms are obtained with specific restriction enzymes (Xba I, Eco RI, Sac I, Apa I, Bgl II, etc) that can also have implications for genetic analysis. DESIGN AND AND METHODS: We studied three unrelated patients; one from Argentina, one from Spain and one from Australia but of Polish origin. Genomic DNA was digested with several different restriction enzymes and probes, amplified and sequenced with an ABI Prism 310 sequencer. RESULTS: In the three patients an abnormal 26 kb band appeared when they were studied with restriction enzyme Bgl II and z probe. A fragment of 944 bp was amplified with primers that cover from -280 to +714 bp of the recognition sequence of Bgl II enzyme (AGATCT) localized 5' from pseudogene z1. After digestion of this PCR product with Bgl II, two fragments of 714 and 280 bp were produced in normal controls, whereas in patient #1 the PCR fragment was undigested and in patients 2 and 3 both undigested and digested fragments were observed. Sequencing of the PCR fragment showed that in all three patients it was the same polymorphism (G->A) at nucleotide 153171 of the 16 p sequence found in the Bgl II recognition site that changed to AAATCT. INTERPRETATION AND CONCLUSIONS: We describe a new polymorphism in the yz1 first exon Bgl II restriction site (G->A). The polymorphism is associated in cis with haplotype -a3.7. The fragment obtained by PCR enabled us to corroborate the presence of the polymorphism quickly without having to use complicated sequencing techniques.

Adult↗
PubMed1999

[The relationship between the persistence of the BCR/ABL gene and relapse in adult patients with acute lymphoblastic leukemia].

BACKGROUND: The Philadelphia chromosome (Ph') is originated by the t(9;22) which determines the rearrangement BCR/ABL. This rearrangement has been associated with an unfavourable prognosis in patients diagnosed with adult acute lymphoblastic leukaemia (ALL). PATIENTS AND METHODS: The BCR/ABL gene (p210 and p190) was prospectively studied by nested RT-PCR in 17 adult patients diagnosed with ALL BCR/ABL-positive cases were monitored by RT-PCR and cytogenetic techniques over the treatment period (LAL-93 AR protocol). RESULTS: BCR/ABL mRNA was detected in 8 out the 17 patients studied (47%). The Ph' chromosome was detected in 4 cases. Follow-up was completed in 6 out of the 8 BCR/ABL positive cases. PCR only became negative in one patient. The 5 patients with persistently positive BCR/ABL relapsed, whereas the case which became negative was still in complete remission after 24 months follow-up. In 3 out of the 4 Ph' positive patients, the karyotype was normal after induction therapy. CONCLUSIONS: This study clearly demonstrates the usefulness of molecular analysis in the diagnosis and follow-up of ALL compared with conventional cytogenetic techniques. The importance of molecular analysis to assess the efficacy of the treatment used has been emphasized and the poor evolution of BCR/ABL-positive patients has been confirmed.

Adolescent↗
PubMed1999

Cleavage of the ALL1 gene in acute lymphoid leukemia before treatment disappears in relapse.

BACKGROUND AND OBJECTIVE: ALL1 gene rearrangements are frequently found in secondary acute leukemias (ALs). A site-specific cleavage of the ALL1 gene in a consensus sequence for topoisomerase II recognition has been considered to be the initial step leading to ALL1 rearrangement and subsequent therapy-related AL. The aim of the present study was to evaluate this cleavage in our patients, to analyze whether it is a laboratory-produced artefact and to check whether it persists or causes a real ALL1 gene rearrangement at relapse. DESIGN AND METHODS: We studied ALL1 rearrangement in 74 cases of AL before treatment by Southern blot avoiding room temperature exposure or delay in processing the samples which could produce ALL1 cleavage. DNA was available for two cases with ALL1 cleavage; it was analyzed by three different Southern blots in one and two in the other. One case with ALL1 cleavage was also studied in relapse. RESULTS: The presence of the cleavage of the ALL1 DNA was found in 3 of 74 (4%) patients. Two of these three patients had the ALL1 cleavage in three and two different analyses. One case was positive for ALL1 cleavage at diagnosis, but negative for both ALL1 cleavage and ALL1 rearrangement at relapse. INTERPRETATION AND CONCLUSIONS: The fact that a constant pattern was obtained from the same patients in different DNA preparations, supports the notion that ALL1 cleavage is not a laboratory artefact. The absence of the cleavage in a sample from a relapsed patient suggests that the subclone with the ALL1 cleavage, in this case, did not play a clear role in the pathogenesis of disease recurrence.

Acute Disease↗
PubMed1999

Erythropoietin plus granulocyte colony-stimulating factor in the treatment of myelodysplastic syndromes. Identification of a subgroup of responders. The Spanish Erythropathology Group.

BACKGROUND AND OBJECTIVE: Anemia leading to transfusion is probably the most important problem in patients with myelodysplastic syndromes (MDS). Human recombinant erythropoietin (rHuEpo) and granulocyte colony-stimulating factor (G-CSF) have been used to treat patients with anemia of MDS, but fewer than 50% respond. The aim of this work was to evaluate the benefit of rHuEpo +/- G-CSF treatment and to isolate the response predictive variables in a group of selected patients with MDS. DESIGN AND METHODS: A non-randomized multicenter trial was carried out in 32 patients with MDS. The inclusion criteria were age >= 18 years, refractory anemia (RA) or refractory anemia with ringed sideroblasts, Hb <= 100 g/L or receiving transfusions and serum erythropoietin <= 250 U/L. These patients were treated with subcutaneous rHuEpo (300 U/kg) three times a week for 8 weeks. In the case of partial response (PR) or no response (NR) subcutaneosly administered G-CSF (1 microg/kg) three times a week was added to the rHuEpo for 8 more weeks. If the patient achieved complete response (CR) or PR in the second phase, he was included in a follow-up phase of 24 weeks in which the dose of growth factors was tapered down. Several variables, including the score published by the Scandinavian-American group, were used as possible predictive variables. RESULTS: An erythroid response was observed in 16 patients (50%); in 12 it was a CR and in 4 it was a PR. During the period of rHuEpo administration, 7 CR and 4 PR (34.4%) were documented. Of the 14 patients in whom G-CSF was added to rHuEpo, 7 (50%) responded (3 CR and 4 PR). No major side-effects associated with growth factors were observed. The multivariate analysis showed that of the different variables evaluated only the Scandinavian-American response score was significant with a relative probability of response of 11.8 (95% confident intervals: 2.5-53) when this score was > +1 (77% of cases responded). In contrast, when this score was <= 1 only 15 % of the cases responded. INTERPRETATION AND CONCLUSIONS: Use of the Scandinavian-American response score is to be recommended in a patient-oriented approach to treating MDS cases with the Epo and G-CSF. Treatment with rHuEpo and G-CSF is safe, its main drawback being its cost. However, a long-term study evaluating the regimen's cost-benefit ratio is warranted.

Adult↗
PubMed1999

Identification of the Hb Lepore phenotype by HPLC.

BACKGROUND AND OBJECTIVE: Hb Lepore is a structurally abnormal hemoglobin in which the abnormal globin chain is a hybrid or fused globin chain (db). Three different Lepore hemoglobins have been identified, differing from each other in the point at which the db fusion occurs; Hb Lepore Hollandia (d22/b50), Hb Lepore Baltimore (d59/b86) and Hb Lepore Boston (d87/b116). In Spain only Hb Lepore Boston and Hb Lepore Baltimore have been identified. Hb Lepore is easily detected by electrophoretic and chromatographic studies, whereas the type of Hb Lepore is distinguished by chromatography of tryptic peptides of abnormal db chain. In this work, we show an easier chromatography technique for identifying the Hb Lepore phenotype. DESIGN AND METHODS: Thirteen different unrelated families (23 patients) from different parts of Spain were studied. The existence of Hb Lepore was diagnosed by standard methodology and quantified by ionic exchange HPLC. The globin chains were studied by reversed phase HPLC, which showed us the phenotype of Hb Lepore; this phenotype was corroborated by a gold standard test using molecular biology techniques. The statistical analysis was designed to determine the behavior of the quantitative (hematologic) variables using the independent variable (Hb Lepore Baltimore or Hb Lepore Boston) categorized by Student's t-test for independent groups. The distribution of the variable was established using theoretical models and the variance homogeneity hypothesis was tested. The validity of the hematologic data was estimated by creating a receiver operating characteristic (ROC) curve. RESULTS: In the study of globin chains by reversed phase HPLC, in 14 patients (8 families) three peaks were eluted; they corresponded to a, b and db globin chains. In these cases when DNA was studied by PCR followed by digestion with the restriction enzyme Pvu II, the phenotype of Hb Lepore was identified as being the Boston variant, whereas in the rest of patients (9 in total), the peak identified with hybrid chain globin (db) was not present and the molecular study showed that these patients were heterozygotes for Hb Lepore Baltimore. INTERPRETATION AND CONCLUSIONS: The study of globin chains by reversed phase HPLC is sufficient to know the phenotype of Hb Lepore and thus tedious techniques such as chromatography of tryptic digestion product of db abnormal chains are not essential, a particularly important consideration in those laboratories that do not have the possibility of carrying out molecular biology studies. Neverteheless, we should continue to use a gold standard molecular biology test in cases of prenatal diagnosis because this technique is the most exact and reproducible that we have.

Chromatography, High Pressure Liquid↗
PubMed1998

Occurrence of BCR-ABL rearrangement in a Philadelphia chromosome-negative patient with 5q and 13q deletions and myeloproliferative syndrome.

We report the case of a patient with a myeloproliferative syndrome and traits of myelodysplasia and myelofibrosis whose karyotype showed 5q and 13q deletions, as well as Philadelphia chromosome negativity. A molecular biology study performed by Southern blot, with a probe covering the M-bcr region, led to detection of three bands other than the germinal ones, which hints at the possible existence of two cut points in the M-bcr region of an allele, or participation of both alleles. The patient presented a complex hematological picture, which might be explained on the basis of the cytogenetic and molecular findings.

Blotting, Southern↗
PubMed1998

[Usefulness of molecular screening in childhood lymphoblastic leukemias].

PURPOSE: To demonstrate that a molecular screening by reverse transcriptase polymerase chain reaction (RT-PCR) of TEL/AML1, E2A/PBX1 and BCR/ABL genes in pediatric acute lymphoblastic leukaemia is a rapid method that allows one to exceed the percentage of adult patients with the BCR/ABL rearrangement. PATIENTS AND METHODS: 12 Spanish children with acute lymphoblastic leukaemia were studied, 11 of them newly diagnosed and 1 relapsed. The patients were between 18 months and 10 years old. Bone marrow aspiration was collected between april and december 1996, RNA was isolated and cDNA was subjected to PCR amplification for TEL/AML1, E2A/PBX1 and BCR/ABL genes. Normal ABL and E2A genes were studied as amplification controls. RESULTS: One of these hybrid genes was found in 33.3% of patients studied. TEL/AML1 in two cases (16.6%), E2A/PBX1 in one case (8.3%) and BCR/ABL in another one (8.3%). CONCLUSIONS: On the basis of these data it would be useful to achieve a molecular screening of TEL/AML1, E2A/PBX1 and BCR/ABL genes in pediatric acute lymphoblastic leukaemia for allowing a molecular classification in a great percentage of patients that exceed the BCR/ABL positivity in adults.

Aneuploidy↗