Carmen Silvia Passos Lima

An inherited mutation leading to production of only the short isoform of GATA-1 is associated with impaired erythropoiesis

Acquired somatic mutations in exon 2 of the hematopoietic transcription factor GATA-1 have been found in individuals with Down syndrome with both transient myeloproliferative disorder and acute megakaryoblastic leukemia. These mutations prevent the synthesis of the full-length protein but allow the synthesis of its short isoform, GATA-1s. Experiments in mice suggest that GATA-1s supports normal adult megakaryopoiesis, platelet formation and erythropoiesis. Here we report a mutation, 332G → C, in exon 2 of GATA1, leading to the synthesis of only the short isoform in seven affected males from two generations of a family. Hematological profiles of affected males demonstrate macrocytic anemia, normal platelet counts and neutropenia in most cases. Altogether, data suggest that GATA-1s alone, produced in low or normal levels, is not sufficient to support normal erythropoiesis. Moreover, this is the first study to indicate that a germline splicing mutation does not lead to leukemia in the absence of other cooperating events, such as Down syndrome.

Increased risk for acute myeloid leukaemia in individuals with glutathione S-transferase mu 1 (GSTM1) and theta 1 (GSTT1) gene defects

Abstract: Objectives: Glutathione S‐transferases (GST) modulate the effects of exposure to various cytotoxic and genotoxic agents, including those associated with increased risks of the myelodysplastic syndrome (MDS), acute myeloid leukaemia (AML) and aplastic anemia (AA). Both the GST mu 1 (GSTM1) and GST theta 1 (GSTT1) genes have a null variant allele in which the entire gene is absent. In this study, we tested whether null genotypes for the GSTM1 and GSTT1 genes altered the risks for MDS, AML and AA. Methods: Genomic DNA from 49 MDS, 38 AML and 37 AA patients and 276 controls was analysed using the polymerase chain reaction (PCR). Results: The frequencies of GSTM1 (73.6%) and GSTT1 (34.2%) null genotypes were significantly higher in AML patients than in the controls (36.9 and 18.1%, respectively). A higher frequency of the combined null genotype for both genes was also observed in patients with AML (26.3% compared with 5.0% in the controls). In contrast, no differences in the frequencies of the null genotypes were found among MDS patients, AA patients and the controls. Conclusion: Our observation of a 4.7‐fold (95% CI: 2.1–11.0) and 2.3‐fold (95% CI: 1.0–5.2) increased risk associated with the GSTM1 and GSTT1 null genotypes, respectively, and a 6.6‐fold (95% CI: 2.4–7.9) increased risk associated with the combined null genotype presents preliminary evidence that the inherited absence of this carcinogen detoxification pathway may be an important determinant of AML.

Inhibition of eosinophil chemotaxis by chronic blockade of nitric oxide biosynthesis

The effect of chronic N omega-nitro-L-arginine methyl ester (L-NAME) treatment on the in vivo eosinophil migration induced by bradykinin, platelet-activating factor (PAF), lipopolysaccharide and carrageenin has been investigated in the rat using the pleurisy model. The in vitro (microchemotaxis chamber) eosinophil migration induced by N-formyl-methionyl-leucyl-phenylalanine (fMLP), PAF and zymosan-activated serum was also evaluated in the rat. The eosinophils were obtained from the peritoneal cavity of male Wistar rats and isolated on a discontinuous metrizamide gradient. Chronic inhibition of nitric oxide biosynthesis was achieved by adding L-NAME to the drinking water to give an intake of approximately 75 mumol/rat/day for 4 weeks. Rats treated chronically with L-NAME developed a significant level of hypertension (163 +/- 4.8 mmHg; P < 0.01) compared with animals which received either the same dose of the inactive enantiomer D-NAME (124 +/- 3.2 mmHg) or tap water alone (119 +/- 1.6 mmHg). The intrapleural injection of bradykinin (50 micrograms), PAF (1 microgram), lipopolysaccharide (0.25 microgram) and carrageenin (125 micrograms) into untreated rats in vivo induced a significant level of eosinophil migration by 24 h post-injection. This migration was markedly reduced in L-NAME-treated rats. Eosinophils obtained from untreated rats showed a significant level of migration in vitro in response to fMLP (5 X 10(-8) M), PAF (10(-8) M) and zymosan-activated serum (27 microliters). In contrast, the migration induced by these chemotactic agents was markedly reduced in cells isolated from animals treated chronically with L-NAME. L-Arginine (5.5 mM), but not D-arginine (5.5 mM), restored the ability of eosinophils from L-NAME-treated animals to migrate in response to fMLP. Our results indicate that nitric oxide plays a major role in the in vivo and ex vivo migration of eosinophils.

Thalidomide plus dexamethasone as a maintenance therapy after autologous hematopoietic stem cell transplantation improves progression-free survival in multiple myeloma

Despite the good response of stem cell transplant (SCT) in the treatment of multiple myeloma (MM), most patients relapse or do not achieve complete remission, suggesting that additional treatment is needed. We assessed the impact of thalidomide in maintenance after SCT in untreated patients with MM. A hundred and eight patients (<70 years old) were randomized to receive maintenance with dexamethasone (arm A; n = 52) or dexamethasone with thalidomide (arm B; n = 56; 200 mg daily) for 12 months or until disease progression. After a median follow‐up of 27 months, an intention to treat analysis showed a 2‐year progression‐free survival (PFS) of 30% in arm A (95% CI 22–38) and 64% in arm B (95% CI 57–71; P = 0.002), with median PFS of 19 months and 36 months, respectively. In patients who did not achieve at least a very good partial response, the PFS at 2 years was significantly higher when in use of thalidomide (19 vs. 59%; P = 0.002). Overall survival at 2 years was not significantly improved (70 vs. 85% in arm A and arm B, respectively; P = 0.27). The addition of thalidomide to dexamethasone as maintenance improved the PFS mainly in patients who did not respond to treatment after SCT. Am. J. Hematol.

N-ras Gene Point Mutations in Brazilian Acute Myelogenous Leukemia Patients Correlate with a Poor Prognosis

The frequency of ras gene mutations varies from 11 to 27% in AML populations from the United States and Europe but it seems that there is no study regarding the frequency of mutated N-ras gene in patients with AML in South America. In order to study the frequency of N-ras gene mutations (exons 1 and 2) in Brazilian patients with AML and to evaluate the possible correlation between the presence of the mutation and clinical features, 40 patients were analyzed. N-ras mutations were identified in DNA samples from eight of 40 AML patients (20%). No significant correlation was found between N-ras mutation and age, sex, race, response to therapy, FAB subtype or occupational exposure. However, the overall survival and AML-free survival were significantly shorter in patients with N-ras mutations than in those without these abnormalities.

Influence of p53 codon 72 exon 4, GSTM1, GSTT1 and GSTP1{*}B polymorphisms in lung cancer risk in a Brazilian population

PURPOSE Glutathione S-transferases (GST) modulates the effects of various cytotoxic and genotoxic agents, particularly those derived from benzo[a]pyrene, which is one of the main tobacco carcinogens. Both the mu 1 (GSTM1) and theta 1 (GSTT1) genes have a null variant allele in which the entire gene is absent. The GSTP1*B allele has an A to G transition at nucleotide 313 (codon 105) in exon 5, causing a change of isoleucine (Ile) to valine (Val), which affects the electrophile binding site of GSTP1 and results in an enzyme with reduced activity. Polymorphisms in these metabolizing enzymes may alter the response to benzo[a]pirene-induced DNA damage. Polymorphisms in p53 may also modulate the risk of lung cancer (LC) carcinogenesis. The aim of our study was to measure the frequency of GSTM1, GSTT1, GSTP1*B and p53 gene polymorphisms in a Brazilian population and determine the possible contribution of these genetic variations to LC risk. PATIENTS AND METHODS Genomic DNA was obtained from 200 Brazilian patients with LC and 264 blood donors (control group). All samples were analyzed by PCR and PCR-RFLP to determine GSTM1, GSTT1, GSTP1*B and p53 codon 72 genotypes. Multiple logistic regressions were used to adjust for confounding factors in this case-control study. RESULTS No statistical significance was observed between GSTM1, GSTT1 and GSTP1*B genetic polymorphisms, either isolated or combined, with LC incidence in the studied population. However, our data showed a higher frequency of p53 codon 72 A/P plus P/P genotype in African-Brazilian than Caucasian-Brazilian patients with LC, and we also found a higher frequency of the P/P genotype of the p53 gene in non-smokers compared to smokers with LC. CONCLUSIONS Genetic polymorphisms of GST and p53 codon 72 did not increase the risk of LC in Brazilian patients. The A/P plus P/P genotype of p53 codon 72 is more common in LC patients with African ethnical background and the P/P genotype more prevalent in non-smoking related LC.

Inflammatory mechanisms underlying the rat pulmonary neutrophil influx induced by airway exposure to staphylococcal enterotoxin type A

Association between staphylococcal infection and pathogenesis of upper airways disease has been reported. This study aimed to investigate the mechanisms underlying the rat pulmonary inflammation induced by airway exposure to staphylococcal enterotoxin A (SEA). SEA (0.3–10 ng trachea−1) caused dose‐dependent neutrophil accumulation in BAL fluid, reaching maximal responses at 4 h (25‐fold increase for 3 ng trachea−1). Significant accumulation of both lymphocytes and macrophages in BAL fluid was also observed at 4 h (2.1‐ and 1.9‐fold increase, respectively, for 3 ng trachea−1). At later times (16 h), neutrophil counts in bone marrow (immature forms) and peripheral blood increased by 63 and 81%, respectively. SEA failed to directly induce chemotaxis and adhesion of isolated neutrophils. Analysis of mRNA expression for iNOS, COX‐2 and CINC‐2 in lung tissue showed an upregulation of these enzymes, which paralleled elevated levels of LTB4, PGE2, TNF‐α, IL‐6 and NO2− in BAL fluid. Expression of CINC‐1 was unchanged, whereas CINC‐3 was reduced in SEA‐treated rats. Incubation of isolated alveolar macrophages with SEA (3 μg ml−1) resulted in significant elevations of TNF‐α and NO2− levels in the cell supernatants. Dexamethasone (0.5 mg kg−1), celecoxib (3 mg kg−1) and compound 1400 W (5 mg kg−1) markedly reduced SEA‐induced lung neutrophil influx and NO2− levels in BAL fluid. The lipoxygenase inhibitor AA‐861 (100 μg kg−1) partly inhibited the neutrophil influx in SEA‐treated rats without modifying the NO2− levels. None of these treatments reduced the number of mononuclear cells in BAL fluid (except of dexamethasone, which abolished the increased lymphocyte counts). Our study shows that airways exposure to SEA results in marked neutrophil influx through mechanisms involving increased expressions of CINC‐2, iNOS and COX‐2, as well as enhanced production of NO, PGE2, LTB4, TNF‐α and IL‐6.

Polymorphisms in the 5′- and 3′-untranslated region of the VEGF gene and sporadic breast cancer risk and clinicopathologic characteristics

AbstractThe wild and the variant alleles of the C936T and G634C vascular endothelial grow factor (VEGF) polymorphisms seem to be linked to higher angiogenic phenotype than the remaining alleles and may act on breast cancer (BC) origin. We investigated the influence of the VEGF C936T and G634C polymorphisms on the occurrence and clinicopathologic characteristics of sporadic breast cancer (SBC) in 235 patients and 235 controls. Peripheral blood samples of all individuals were analysed by the polymerase chain reaction for identification of genotypes and by enzyme-linked immunosorbent assay (ELISA) for quantification of serum VEGF levels. The variant 634CC genotype isolated (16.2% versus 10.7%, P  = 0.01) and in combination with the wild 936CC genotype (10.6% versus 5.5%, P  = 0.01) were more common in patients than in controls. The carriers of the respective genotypes were under a 2.20-fold and a 3.08-fold increased risks for the disease. Additionally, the frequency of the wild 936CC genotype was higher in patients with tumours of histological grade III compared to those with tumours of I+II histological grades (84.0% versus 64.7%, P  = 0.004) and in patients with positive oestrogen receptor tumours compared to those with tumours lacking oestrogen receptor expression (84.7% versus 73.9%, P  = 0.02). Similar serum values of VEGF were seen in patients and controls with the distinct genotypes of the VEGF. The data suggest that the VEGF wild 936CC and the variant 634CC genotypes constitute inherited determinants of SBC and SBC aggressiveness in Brazil, but are not significant predictors of circulating VEGF levels.

Camptothecins Compared with Etoposide in Combination with Platinum Analog in Extensive Stage Small Cell Lung Cancer: Systematic Review with Meta-Analysis

Introduction: Superiority of camptothecin regimens over etoposide—both combined with platinum analogs—in extensive disease small cell lung cancer has been a matter of debate with contradictory findings in randomized trials. A systematic review was sought to elucidate this issue. Methods: Randomized controlled trials comparing first-line camptothecin-platinum doublets versus etoposide-platinum doublets in patients with extensive disease small cell lung cancer were searched in MEDLINE, EMBASE, LILACS, and CENTRAL databases, European Society of Medical Oncology, American Society of Clinical Oncology, and International Association for the Study of Lung Cancer meeting sites. Meta-analyses were performed using fixed-effects model. Subgroup analyses were undertaken comparing each type of camptothecin to etoposide-based regimens. The outcomes of interest were overall survival (OS), progression-free survival (PFS), response rate (RR), and toxicities. Results: Eight studies (3086 patients) were included. The meta-analysis of topotecan regimens (TP) was not reliable due to impending heterogeneity. Meta-analysis of trials testing irinotecan combinations (IP) versus etoposide regimens (EP; 1561 patients) stated an OS improvement in favor of IP arm, though with considerable heterogeneity, whose origin seemed to be a Japanese trial. In the analyses without that study (1407 patients left), IP brought a significant improvement in OS (hazard ratio = 0.87; 95% confidence interval 0.78–0.97; p = 0.02; I2 = 0). IP also increased PFS (hazard ratio = 0.83; 95% confidence interval 0.73–0.95; p = 0.006; I2 = 0%). There was no impact in RR (absolute RR 56% with IP; 53% with EP; p = 0.17). IP caused more diarrhea (p < 0.0001) but less hematological toxicities (p < 0.001) than EP. Conclusions: The present meta-analysis demonstrates statistically significant OS and PFS benefits of IP over EP regimens in western and eastern patients. Specific characteristics of safety profile should be taken into account when administrating IP chemotherapy.

Long-term hydroxyurea therapy in beta-thalassaemia patients.

Objective: The study aimed to investigate the use of hydroxyurea (HU) for the treatment of beta‐thalassaemia (β‐thal) patients.