Association between methylene tetrahydrofolate reductase and glutathione S-transferase M1 gene polymorphisms and chronic myeloid leukemia in a Brazilian population.

Chronic myeloid leukemia is a hematopoietic stem cell disorder that causes uncontrolled proliferation of white blood cells. Although the clinical and biological aspects are well documented, little is known about individual susceptibility to this disease. We conducted a case-control study analyzing the prevalence of the polymorphisms MTHFR C677T, MTHFR A1298C, del{GSTM1}, del{GSTT1}, and haptoglobin in 105 patients with chronic myeloid leukemia (CML) and 273 healthy controls, using PCR-based methods. A significant association with risk of developing CML was found for MTHFR 1298AA (odds ratio (OR) = 1.794; 95% confidence interval (CI) = 1.14-2.83) and GSTM1 non-null (OR = 1.649; 95%CI = 1.05-2.6) genotypes, while MTHFR 1298AC (OR = 0.630; 95%CI = 0.40-0.99) and GSTM1 null (OR = 0.606; 95%CI = 0.21-0.77) genotypes significantly decreased this risk. There appeared to be selection for heterozygosity at the MTHFR 1298 locus. The considerable range of variation in this and other human populations may be a consequence of distinctive processes of natural selection and adaptation to variable environmental conditions. The Brazilian population is very mixed and heterogeneous; we found these two loci to be associated with CML in this population.

Evidence for an association between haptoglobin and MnSOD (Val9Ala) gene polymorphisms in essential hypertension based on a Brazilian case-control study.

Essential hypertension is a complex and multifactorial trait; genetic and environmental factors interact to produce the final phenotype. Studies have demonstrated association of hypertension with varied gene polymorphisms. However, demonstration of common genetic causes in the general population remains elusive. We investigated a possible association between hypertension and haptoglobin, angiotensin I-converting enzyme (ACE), glutathione S-transferases GSTM1 and GSTT1, MnSOD (Val9Ala), CAT (-21A/T), and GPX1 (Pro198Leu) gene polymorphisms in an urban Brazilian population group from Brasília. Although ACE has been reported to be one of the main polymorphisms associated with hypertension, we found no association with ACE's specific genotypes. However, a possible association with Hp1-1 and MnSOD Val/Ala genotypes suggests that, at least for the Brazilian population, polymorphisms related to oxidative stress should be more deeply investigated.

Antioxidant effect of haptoglobin phenotypes against DNA damage induced by hydrogen peroxide in human leukocytes.

Human haptoglobin is classified into three major phenotypes: Hp1-1, Hp2-1 and Hp2-2; there are two autosomal alleles Hp*1 and Hp*2, and the Hp*1 allele has two subtypes, Hp*1F and Hp*1S. Haptoglobin acts as an antioxidant, preventing hemoglobin-driven oxidative damage. We used the comet assay to examine oxidative damage to DNA induced by hydrogen peroxide in human leukocytes; we also looked for differences in the antioxidant capacity of haptoglobin subtypes. Haptoglobin genotypes were determined through allele-specific polymerase chain reaction, visualized on a polyacrylamide gel. The Hp1-1 genotype had the least DNA damage; this indicates that Hp alleles differ in their protective effects against oxidative damage. Among Hp*1 alleles, Hp*1F was the most protective.

Dietary carotenoid-rich pequi oil reduces plasma lipid peroxidation and DNA damage in runners and evidence for an association with MnSOD genetic variant -Val9Ala.

Physical training induces beneficial adaptations; however, exhausting exercise increases reactive oxygen species generation, resulting in damage to DNA and tissues. Pequi (Caryocar brasiliense), a fruit of the Brazilian Cerrado, contains a carotenoid-rich oil. We investigated whether pequi oil had antioxidant effects in runners. Evaluations were made after outdoor races before and after ingestion of 400 mg pequi-oil capsules for 14 days. Blood samples were taken after races and submitted to comet and TBARS assays and biochemical analyses of creatine kinase (CK), aspartate aminotransferase (AST) and alanine aminotransferase (ALT). To determine if the protective effects of pequi-oil were influenced by antioxidant enzyme genotypes, MnSOD (-Val9Ala), CAT (-21A/T) and GPX1 (Pro198Leu) gene polymorphisms were also investigated. Pequi oil was efficient in reducing tissue injuries evaluated for AST and ALT, particularly in women, and in reducing DNA damages in both sexes. Except for CK levels, the results were influenced by MnSOD genotypes; heterozygous excess was related to less DNA damage, tissue injury and lipid peroxidation, besides presenting a better response to pequi oil against exercise-induced damage.

First Report of Anthracnose Caused by Colletotrichum gloeosporioides on Gueroba in Brazil.

Gueroba (Syagrus oleracea (Mart.) Becc.), a member of the family Arecaceae, is an important native palm tree in central Brazil and has great potential as a cultivated crop and ornamental plant (1). In July 1999, anthracnose symptoms were observed on several gueroba plants growing in a field in Planaltina, Federal District. Leaves showed spots or small circular to irregular, brown-to-black necrotic lesions, which generally coalesced as symptoms progressed. Tissue sections from leaves with symptoms were plated aseptically on potato dextrose agar (PDA). A fungus was consistently isolated from leaves of symptomatic plants and was identified as Colletotrichum gloeosporioides (Penzig) Penzig & Sacc. by P. F. Cannon of CABI Bioscience, Egham, UK, where a culture (IMI 384186) has been deposited. An isolate was tested for pathogenicity by inoculating 20 plants at the two-leaf stage by placing a mycelial PDA plug from a 10-day-old fungal culture on a previously wounded leaf. Noninoculated plants served as controls. Plants were enclosed in a plastic bag and incubated for 4 days at 26 ± 2°C and ≈100% relative humidity. Ten days after inoculation, plants developed leaf lesions similar to those observed in the field. Symptoms did not develop on the control plants. C. gloeosporioides was reisolated from 95% of the inoculated leaves, completing Koch's postulates. The pathogenicity test was repeated with the same results. To our knowledge, this is the first report of C. gloeosporioides causing anthracnose on gueroba in Brazil. Reference: (1) H. Lorenzi. Page 288 in: Árvores Brasileiras. Plantarum. Nova Odessa, Brazil 1998.