Sérgio Paulo Bydlowski

Color and genomic ancestry in Brazilians: a study with forensic microsatellites.

The population of Brazil, formed by extensive admixture between Amerindians, Europeans and Africans, is one of the most variable in the world. We have recently published a study that used ancestry-informative markers to conclude that in Brazil, at an individual level, color, as determined by physical evaluation, was a poor predictor of genomic ancestry, estimated by molecular markers. To corroborate these findings we undertook the present investigation based on data from 12 commercially available forensic microsatellites that were utilized to estimate the personal genomic origin for each of 752 individuals from the city of São Paulo, belonging to different Brazilian color categories (275 Whites, 192 Intermediates and 285 Blacks). The genotypes permitted the calculation of a personal likelihood-ratio estimator of African or European ancestry. Although the 12 marker set proved capable of discriminating between European and African individuals, we observed very significant overlaps among the three color categories of Brazilians. This was confirmed quantitatively using a Bayesian analysis of population structure that did not demonstrate significant genetic differentiation between the three color groups. These results corroborate and validate our previous conclusions using ancestry-informative markers that in Brazil at the individual level there is significant dissociation of color and genomic ancestry.

DNA tests probe the genomic ancestry of Brazilians

We review studies from our laboratories using different molecular tools to characterize the ancestry of Brazilians in reference to their Amerindian, European and African roots. Initially we used uniparental DNA markers to investigate the contribution of distinct Y chromosome and mitochondrial DNA lineages to present-day populations. High levels of genetic admixture and strong directional mating between European males and Amerindian and African females were unraveled. We next analyzed different types of biparental autosomal polymorphisms. Especially useful was a set of 40 insertion-deletion polymorphisms (indels) that when studied worldwide proved exquisitely sensitive in discriminating between Amerindians, Europeans and Sub-Saharan Africans. When applied to the study of Brazilians these markers confirmed extensive genomic admixture, but also demonstrated a strong imprint of the massive European immigration wave in the 19th and 20th centuries. The high individual ancestral variability observed suggests that each Brazilian has a singular proportion of Amerindian, European and African ancestries in his mosaic genome. In Brazil, one cannot predict the color of persons from their genomic ancestry nor the opposite. Brazilians should be assessed on a personal basis, as 190 million human beings, and not as members of color groups.

Synthesis and Characterization of a Metal Complex Containing Naringin and Cu, and its Antioxidant, Antimicrobial, Antiinflammatory and Tumor Cell Cytotoxicity

The antioxidant activity of flavonoids is believed to increase when they are coordinated with transition metal ions. However, the literature on this subject is contradictory and the outcome seems to largely depend on the experimental conditions. In order to understand the contribution of the metal coordination and the type of interaction between a flavonoid and the metal ion, in this study a new metal complex of Cu (II) with naringin was synthesized and characterized by FT-IR, UV-VIS, mass spectrometry (ESI-MS/MS), elemental analysis and 1H-NMR. The results of these analyses indicate that the complex has a Cu (II) ion coordinated via positions 4 and 5 of the flavonoid. The antioxidant, anti-inflammatory and antimicrobial activities of this complex were studied and compared with the activity of free naringin. The Naringin-Cu (II) complex 1 showed higher antioxidant, anti-inflammatory and tumor cell cytotoxicity activities than free naringin without reducing cell viability.

Características biológicas das células-tronco mesenquimais

Celulas-tronco sao celulas indiferenciadas. Como tal, apresentam uma serie de caracteristicas que as tornam candidatas a utilizacao terapeutica. As principais caracteristicas das celulas-tronco sao a capacidade de autorrenovacao e de se diferenciarem em diversos tipos celulares. Desta forma, acredita-se que celulas-tronco presentes nos diferentes tecidos tenham papel regenerativo quando estes sofrem uma lesao ou injuria. Entre os tecidos conhecidos por apresentarem celulas-tronco apos a vida pos-natal, a medula ossea foi a mais estudada, por muitos anos, como fonte tanto de celulas-tronco hematopoeticas quanto de celulas-tronco mesenquimais, tambem denominadas de celulas mesenquimais estromais da medula ossea ou celulas estromais mesenquimais multipotentes. Estas celulas sao um grupo de celulas clonogenicas, presentes no estroma da medula ossea, que, quando submetidas a diferentes estimulos apropriados, sao capazes de se diferenciarem em varias linhagens de celulas, como a osteogenica, a condrogenica e a adipogenica e, possivelmente, em outros tipos celulares nao mesodermicos, como celulas neurais ou hepatocitos. Nesta revisao, as principais caracteristicas das celulas-tronco mesenquimais serao abordadas, incluindo os marcadores moleculares e de membrana, as caracteristicas de divisao e de diferenciacao, a heterogeneidade e as aplicacoes clinicas potenciais.

Ethnicity and glutathione S-transferase (GSTM1/GSTT1) polymorphisms in a Brazilian population

The distribution of polymorphisms related to glutathione S-transferases (GST) has been described in different populations, mainly for white individuals. We evaluated the distribution of GST mu (GSTM1) and theta (GSTT1) genotypes in 594 individuals, by multiplex PCR-based methods, using amplification of the exon 7 of CYP1A1 gene as an internal control. In São Paulo, 233 whites, 87 mulattos, and 137 blacks, all healthy blood-donor volunteers, were tested. In Bahia, where black and mulatto populations are more numerous, 137 subjects were evaluated. The frequency of the GSTM1 null genotype was significantly higher among whites (55.4%) than among mulattos (41.4%; P = 0.03) and blacks (32.8%; P < 0.0001) from São Paulo, or Bahian subjects in general (35.7%; P = 0.0003). There was no statistically different distribution among any non-white groups. The distribution of GSTT1 null genotype among groups did not differ significantly. The agreement between self-reported and interviewer classification of skin color in the Bahian group was low. The interviewer classification indicated a gradient of distribution of the GSTM1 null genotype from whites (55.6%) to light mulattos (40.4%), dark mulattos (32.0%) and blacks (28.6%). However, any information about race or ethnicity should be considered with caution regarding the bias introduced by different data collection techniques, specially in countries where racial admixture is intense, and ethnic definition boundaries are loose. Because homozygous deletions of GST gene might be associated with cancer risk, a better understanding of chemical metabolizing gene distribution can contribute to risk assessment of humans exposed to environmental carcinogens.

Metabolism of a cholesterol-rich microemulsion (LDE) in patients with multiple myeloma and a preliminary clinical study of LDE as a drug vehicle for the treatment of the disease

PurposePreviously we have shown that cholesterol-rich microemulsions that bind to LDL receptors have the ability to concentrate in acute myeloid leukemia cells and in ovarian and breast carcinomas. Thus, LDE may be used as a vehicle for drugs directed against neoplastic cells. Indeed, we subsequently showed that when carmustine is associated with LDE the toxicity of the drug is significantly reduced in patients with advanced cancers. The aim of the present study was to verify whether LDE may be taken up by multiple myeloma cells and whether patients with multiple myeloma respond to treatment with LDE associated with carmustine.MethodsA total of 131 consecutive volunteer patients with recently diagnosed multiple myeloma classified as clinical stage IIIA had their plasma lipid profile determined. LDE plasma kinetics were performed in 14 of them. Cell uptake of LDE and the cytotoxicity of carmustine associated with the emulsion were evaluated in a multiple myeloma cell line. A pharmacokinetic study of LDE-carmustine was performed in three patients. Finally, an exploratory clinical study of LDE-carmustine (carmustine dose 180 mg/m2 body surface every 4 weeks) was performed in seven untreated multiple myeloma patients.ResultsLDL cholesterol was lower in the 131 multiple myeloma patients than in healthy controls and the fractional clearance rate (FCR, in units per minute) in the 14 multiple myeloma patients was twice that in 14 paired healthy control subjects. Moreover, entry of LDE into multiple myeloma cells was shown to be mediated by LDL receptors. Taken together, these findings indicate that LDE may target multiple myeloma. The exploratory clinical study showed that gammaglobulin decreased by 10-70% (mean 36%) after three cycles and by 25-75% (mean 44%) after six cycles. Furthermore, there was amelioration of symptoms in all patients. Cholesterol concentrations increased after treatment, suggesting that the treatment resulted in at least partial destruction of neoplastic cells with receptor upregulation. Side effects of the treatment were negligible.ConclusionsBecause it targets multiple myeloma and, when associated with an antineoplastic agent, produces therapeutic responses in patients with fewer side effects, LDE has the potential for use as a drug vehicle in the treatment of the disease.

The Phylogeography of African Brazilians

Background/Aims: Approximately four million Africans were taken as slaves to Brazil, where they interbred extensively with Amerindians and Europeans. We have previously shown that while most White Brazilians carry Y chromosomes of European origin, they display high proportions of African and Amerindian mtDNA lineages, because of sex-biased genetic admixture. Methods: We studied the Y chromosome and mtDNA haplogroup structure of 120 Black males from Sao Paulo, Brazil. Results: Only 48% of the Y chromosomes, but 85% of the mtDNA haplogroups were characteristic of sub-Saharan Africa, confirming our previous observation of sexually biased mating. We mined literature data for mtDNA and Y chromosome haplogroup frequencies for African native populations from regions involved in Atlantic Slave Trade. Principal Components Analysis and Bayesian analysis of population structure revealed no genetic differentiation of Y chromosome marker frequencies between the African regions. However, mtDNA examination unraveled considerable genetic structure, with three clusters at Central-West Africa, West Africa and Southeast Africa. A hypothesis is proposed to explain this structure. Conclusion: Using these mtDNA data we could obtain for the first time an estimate of the relative ancestral contribution of Central-West (0.445), West (0.431) and Southeast Africa (0.123) to African Brazilians from Sao Paulo. These estimates are consistent with historical information.

Endothelial cell dysfunction correlates differentially with survival in primary and secondary pulmonary hypertension.

BACKGROUND Plasma von Willebrand factor antigen (vWF:Ag) has been used as a marker of endothelial perturbation in a number of vascular disorders. In this study, vWF:Ag was determined as an attempt to evaluate the severity of endothelial cell dysfunction in primary pulmonary hypertension (PPH) and congenital heart disease-associated pulmonary hypertension (CHD-PH) comparatively and to determine its impact on short-term survival. METHODS AND RESULTS Clinical, hemodynamic, and biochemical data were obtained from 11 patients with PPH and 24 with CHD-PH. Patient groups were similar in terms of age and pulmonary artery pressure. vWF:Ag was measured by electroimmunodiffusion. Patients were followed up for 1 year and at that time, data collected at the beginning of the study were subjected to univariate and multivariate analyses. vWF:Ag was increased in patients (normal reference value 87% +/- 23% activity, mean +/- SD), with higher levels in the PPH group (231% +/- 89%) in comparison with the CHD-PH group (127% +/- 68%) (P <.001). Multivariate analysis showed that survival was influenced by the underlying cause of pulmonary hypertension and vWF:Ag levels but not by patient age, sex, or pulmonary artery pressure. Seven of 10 nonsurvivors but only 4 of 25 survivors had PPH (P =.007). vWF:Ag was 255% +/- 90% in the nonsurvivor group and 121% +/- 54% in the survivors (P <.001). CONCLUSIONS Our findings suggest that short-term survival is related to the severity of endothelial cell dysfunction in pulmonary hypertension. In addition, exceedingly high vWF:Ag levels in PPH might reflect a particular pattern of endothelial cell dysfunction that could be associated with decreased short-term life expectancy in this disorder compared with secondary forms of pulmonary hypertension.

Polymorphisms in the methylenetetrahydrofolate reductase and methionine synthase reductase genes and homocysteine levels in Brazilian children

Hyperhomocysteinemia is a risk factor for thrombosis, and methylenetetrahydrofolate reductase (MTHFR) and methionine synthase reductase (MTRR) polymorphisms, folate, and B12 levels could contribute to plasma homocysteine (Hcy) variation. Although well established in adults, few studies have been performed in childhood. In this study, we investigated association of polymorphisms C677T and A1298C in the MTHFR gene and A66G in the MTRR gene with Hcy levels in children. These polymorphisms, as well as Hcy, folate, and vitamin B12 levels were investigated in 220 normal children with ages ranging from 1 to 8 years. Plasma Hcy, folate, and vitamin B12 levels were normal in all children. None of the polymorphisms could be considered an independent risk factor for hyperhomocysteinemia during childhood. The median Hcy levels in 37 children (17%) doubly heterozygous for C677T and A1298C mutations in the MTHFR gene were not different from the other genotypes. However, the association of the different genotypes with Hcy, folate, and vitamin B12 levels demonstrated significant P‐values. The folate levels demonstrated a statistically significant decrease (P = 0.0477) from the C677T mutation in the MTHFR gene (TT genotype) when compared to the other groups. Folate was the only independent risk factor for hyperhomocysteinemia. Thus, monitoring the concentrations of folate would be more helpful for evaluating hyperhomocysteinemia and for preventing cardiovascular disease.

Evaluation of Distinct Freezing Methods and Cryoprotectants for Human Amniotic Fluid Stem Cells Cryopreservation

Amniotic fluid (AF) was described as a potential source of mesenchymal stem cells (MSCs) for biomedicine purposes. Therefore, evaluation of alternative cryoprotectants and freezing protocols capable to maintain the viability and stemness of these cells after cooling is still needed. AF stem cells (AFSCs) were tested for different freezing methods and cryoprotectants. Cell viability, gene expression, surface markers, and plasticity were evaluated after thawing. AFSCs expressed undifferentiated genes Oct4 and Nanog; presented typical markers (CD29, CD44, CD90, and CD105) and were able to differentiate into mesenchymal lineages. All tested cryoprotectants preserved the features of AFSCs however, variations in cell viability were observed. In this concern, dimethyl sulfoxide (Me2SO) showed the best results. The freezing protocols tested did not promote significant changes in the AFSCs viability. Time programmed and nonprogrammed freezing methods could be used for successful AFSCs cryopreservation for 6 months. Although tested cryoprotectants maintained undifferentiated gene expression, typical markers, and plasticity of AFSCs, only Me2SO and glycerol presented workable viability ratios.