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Biomedical subjects

A P de Souza

Publications and source records attributed to A P de Souza.

At least 19 recordsLinked to original sources
PubMed2005

Tropical maize germplasm: what can we say about its genetic diversity in the light of molecular markers?

Knowledge about genetic variability of a crop allows for more efficient and effective use of resources in plant improvement programs. The genetic variation within temperate maize has been studied extensively, but the levels and patterns of diversity in tropical maize are still not well understood. Brazilian maize germplasm represents a very important pool of genetic diversity due to many past introductions of exotic material. To improve our knowledge of the genetic diversity in tropical maize inbred lines, we fingerprinted 85 lines with 569 AFLP bands and 50 microsatellite loci. These markers revealed substantial variability among lines, with high rates of polymorphism. Cluster analysis was used to identify groups of related lines. Well-defined groups were not observed, indicating that the tropical maize studied is not as well organized as temperate maize. Three types of genetic distance measurements were applied (Jaccard's coefficient, Modified Rogers' distance and molecular coefficient of coancestry), and the values obtained with all of them indicated that the genetic similarities were small among the lines. The different coefficients did not substantially affect the results of cluster analysis, but marker types had a large effect on genetic similarity estimates. Regardless of genetic similarity coefficient used, estimates based on AFLPs were poorly correlated with those based on SSRs. Analyses using AFLP and SSR data together do not seem to be the most efficient manner of assessing variability in highly diverse materials because the result was similar to using AFLPs alone. It was seen that molecular markers can help to organize the genetic variability and expose useful diversity for breeding purposes.

Brazil↗
PubMed2005

Analysis of the MMP-9 (C-1562 T) and TIMP-2 (G-418C) gene promoter polymorphisms in patients with chronic periodontitis.

BACKGROUND: Matrix metalloproteinases (MMP)-9 is an important member of the matrix metalloproteinase family. A functional polymorphism has been described in the promoter region of the human MMP-9 gene. A C-to-T base exchange at -1562 creates two different alleles, and the C/T and T/T genotypes promote high activity of the MMP-9 gene promoter, increasing the risk for inflammatory diseases. The metalloproteinase-2 tissue inhibitor (TIMP-2) regulates the activity of MMPs in the extracellular matrix, and a polymorphism at the -418 position of the TIMP-2 gene promoter has been found in a Sp-1 binding site. In this study we have investigated the association between the above-mentioned polymorphisms and chronic periodontitis severity. METHODS: Genomic DNA from oral mucosa of 100 subjects was amplified by polymerase chain reaction and analysed by restriction endonuclease digestion. The significance of the differences in observed frequencies of polymorphisms in moderate and severe disease and healthy groups was assessed by chi(2) test (p<0.05). RESULTS: No association was observed between the polymorphism in the promoter region of MMP-9 (p=0.6693) and chronic periodontitis. The analysis of TIMP-2 showed that the G/G genotype was found at a frequency of 99%. CONCLUSION: The results show that the polymorphism in the promoter region of MMP-9 gene is not associated with chronic periodontitis. The high frequency of GG genotype in the TIMP-2 gene promoter in the population studied did not allow any conclusion regarding its effect on chronic periodontitis.

Adult↗
PubMed2004

Inhibition of human pulpal gelatinases (MMP-2 and MMP-9) by zinc oxide cements.

The interaction between metal ions and the oral environment is a major subject matter in dental research. Matrix metalloproteinases (MMPs) have been implicated in several pathological and physiological processes such as, periodontal tissue destruction, root caries, dentin calcification and pulpal inflammation. The aim of this work was to test the effect of zinc released from zinc oxide-eugenol (ZOE) cements, on the activity of the major pulpal gelatinolytic MMPs. Pulpal explants were cultured overnight in Dulbecco's Modified Eagle Medium and the activity of secreted enzymes was analysed by gelatin zymography in buffer conditioned with diverse ZOE cements. Phenanthroline, a zinc chelator, was used to revert the inhibition of MMPs caused by zinc. The major gelatinolytic proteinases present in the conditioned media were characterized as MMP-2 and MMP-9 by immunoprecipitation. All ZOE cements inhibited MMPs activity, whereas phenanthroline could partially revert the inhibition caused by plain ZOE and Intermediate Restorative Material (IRM).

Chelating Agents↗
PubMed2003

Analysis of the TGF-beta1 promoter polymorphism (C-509T) in patients with chronic periodontitis.

BACKGROUND: A polymorphism in the promoter region of the transforming growth factor beta-1 (TGF-beta1) gene was described at position -509. This polymorphism represents a C-to-T base exchange, which creates a YY1 consensus sequence in an area involved with down transcription regulation. This polymorphism has been associated with risk for asthma and allergies. In this study we investigated the association between this polymorphism and chronic periodontitis severity. METHODS: Genomic DNA from oral mucosa of 87 Caucasian subjects was amplified by PCR, and digested with Eco81I restriction endonuclease. The alleles were separated by polyacrylamide gel electrophoresis. The differences in genotype distribution from those expected by Hardy-Weinberg equilibrium, and the significance of the differences in observed frequencies of the polymorphism in moderate and severe disease and healthy groups were assessed by the chi2 test. RESULTS: There was a difference in the presence of the different alleles and genotypes among the healthy, moderate and severe periodontitis groups. The allele T was seen at 57.7% in the group with severe periodontitis and 37.8% and 35.4% in the healthy group and moderate periodontitis group, respectively (p=0.0387). The genotype T/T was found at 38.5% in the group with severe periodontitis, and at a frequency of 8% in the healthy group (p=0.0258). CONCLUSION: These results demonstrate that the polymorphism at bp -509 in the TGF-beta1 promoter may have a small effect on the modulation of the inflammatory process during periodontitis.

Adult↗
PubMed2003

Polymorphism at position -174 of IL-6 gene is associated with susceptibility to chronic periodontitis in a Caucasian Brazilian population.

BACKGROUND: Interleukin-6 (IL-6) is a multifunctional cytokine that mediates inflammatory tissue destruction. A G to C substitution at position -174 in the promoter of IL-6 gene reduces in vitro transcription of IL-6. This polymorphism has been associated with inflammatory diseases like chronic arthritis. OBJECTIVE: The aim of this study was to investigate the association between the IL-6-174 polymorphism and susceptibility to chronic periodontitis in Brazilians. MATERIAL AND METHODS: Eighty-four nonsmoking subjects over 25 years (mean age 42.4) were divided according to the severity level of periodontal disease: 36 healthy individuals (control group), 24 subjects with moderate and 24 with severe periodontitis. Genomic DNA was obtained from epithelial cells through a mouthwash with 3% glucose and scraping of oral mucosa. The samples were analyzed for IL-6-174 polymorphism using PCR-RFLP. The significance of the differences in the frequencies of the polymorphism in the control and groups with periodontitis was assessed by chi2 test (p<0.05). RESULTS: Differences were found between control and groups with periodontitis in the genotype (p=0.0036, OR=3.0) and in the allele (p=0.0838, OR=1.9) frequencies. CONCLUSION: We concluded that the IL-6-174 polymorphism is associated with susceptibility to chronic periodontitis in the population studied.

Adult↗
PubMed2003

MMP-1 promoter polymorphism: association with chronic periodontitis severity in a Brazilian population.

BACKGROUND: A single nucleotide polymorphism was described in the promoter region of the human MMP-1 gene, and this polymorphism has been associated with risk of cancer metastasis and inflammatory diseases. In this paper, we studied the possible relationship between the MMP-1 promoter polymorphism and the severity of chronic periodontitis. METHODS: Genomic DNA from oral mucosa was amplified by PCR and analyzed by restriction endonuclease. The alleles were separated by polyacrylamide gel electrophoresis. The significance of the differences in observed frequencies of polymorphism in moderate and severe disease and healthy groups was assessed by Chi-squared test. RESULTS: In the healthy group, the 2G allele was observed with a frequency of 48.7%, while in severely diseased patients the 2G allele was seen in 69.2% (P = 0.0344). The genotype 2G/2G was found in 46.15% of the group with severe periodontitis, and 24.3% and 25.0%, respectively, of the healthy and moderate groups (P = 0.0647). CONCLUSION: These results show that a polymorphism in the promoter region of MMP-1 gene is associated with the severe chronic periodontitis phenotype in non-smokers.

Adult↗
PubMed2003

Absence of interferon-gamma-inducible gene IGTP does not significantly alter the development of chagasic cardiomyopathy in mice infected with Trypanosoma cruzi (Brazil strain).

Interferon-gamma (IFN-gamma) contributes to host resistance during acute infection with Trypanosoma cruzi, the causative agent of Chagas' disease. Inducibly expressed guanosine triphosphatase (IGTP), a 48-kDa guanosine triphosphatase (GTPase), is a member of a family of GTPase proteins inducibly expressed by IFN-gamma. The expression pattern of IGTP suggests that it may mediate IFN-gamma-induced responses in a variety of cell types. IGTP has been demonstrated to be important for control of Toxoplasma gondii infection but not for resistance against Listeria monocytogenes. We evaluated the role of IGTP in development of chronic chagasic cardiomyopathy in IGTP null mice and C57X129sv (wild type [WT]) mice infected with the Brazil strain for 6 mo. There was no significant difference in parasitemia or cardiac histopathology between null and WT mice. Right ventricular remodeling was observed in infected IGTP null mice, suggesting that IGTP does not significantly alter the course of T. cruzi infection.

Animals↗
PubMed2001

Marchantia polymorpha mitochondrial orf identifies transcribed sequence in angiosperm mitochondrial genome.

Heterologous hybridizations performed using nine Marchantia polymorpha mitochondrial orfs and the sdh4 gene against angiosperm mtDNA suggested that three of them and the sdh4 gene have been conserved in the mitochondrial genome of different angiosperm species. Solanum tuberosum mtDNA fragments, which hybridized to M. polymorpha orf207 and sdh4 gene, were cloned, sequenced, and their expressions evaluated by Northern and RT-PCR. Hybridizing fragments to sdh4 gene and orf207 from potato mtDNA were shown to be transcribed, but only in the case of sdh4 gene was there homology between the protein encoded by the DNA sequence from M. polymorpha and the potato mitochondrial genome. M. polymorpha orf207 showed little similarity to an open reading frame from potato mtDNA, named here orf78. The putative proteins encoded by both orf207 and orf78 were not related, indicating that these orfs do not constitute homologous sequences.

Amino Acid Sequence↗
PubMed2000

Mapping analysis of the Xylella fastidiosa genome.

A cosmid library was made of the 2.7 Mb genome of the Gram-negative plant pathogenic bacterium Xylella fastidiosa and analysed by hybridisation mapping. Clones taken from the library as well as genomic restriction fragments of rarely cutting enzymes were used as probes. The latter served as a backbone for ordering the initial map contigs and thus facilitated gap closure. Also, the co-linearity of the cosmid map, and thus the eventual sequence, could be confirmed by this process. A subset of the eventual clone coverage was distributed to the Brazilian X.FASTIDIOSA: sequencing network. Data from this effort confirmed more quantitatively initial results from the hybridisation mapping that the redundancy of clone coverage ranged between 0 and 45-fold across the genome, while the average was 15-fold by experimental design. Reasons for this not unexpected fluctuation and the actual gaps are being discussed, as is the use of this effect for functional studies.

Brazil↗
PubMed2000

Enzymatic markers of heart lesion in mice infected with Trypanosoma cruzi and submitted to benznidazole chemotherapy.

Creatine kinase (CK total and CK-MB) were studied as markers of lesion progression induced by Trypanosoma cruzi infection. After 3 weeks mice infected with 10(4) parasites showed an increase in both enzyme levels and in their frequency distribution. A trend to increase was already detected in the 2nd week. A short duration per os treatment with benznidazole (Bz) prevented the occurrence of tissue lesions, since no changes were observed in enzymes. However, in the 4th week, about 40% of Bz-treated mice showed an increase in CK-MB, as did those that survived until the 8th week. Long-term treatment with Bz in drinking water of mice infected with 10(2) parasites showed, after 32 weeks, a partial reversion of the occurrence of high CK-MB levels from 85.7% to 50%. We found a positive correlation between inflammatory infiltrates and CK-MB levels, indicating that this marker could be useful to monitor the occurrence of experimental chagasic myocarditis.

Animals↗
PubMed2000

Inhibition of human gingival gelatinases (MMP-2 and MMP-9) by metal salts.

OBJECTIVES: The interaction between metal ions and the oral environment is a major subject matter in dental research. Matrix metalloproteinases (MMPs) have been implicated in several pathologic oral processes such as periodontal tissue destruction, root caries, tumour invasion and temporomandibular joint disorders. The aim of this work was to test the effect of Zn, Cu, Sn and Hg ions on the activity of the major gingival gelatinolytic MMPs. METHODS: Gingival explants were cultured overnight in DMEM and the activity of secreted enzymes was analyzed by gelatin zymography in buffers containing different metal ion concentrations. The major gelatinolytic proteinases present in the conditioned media were characterized as MMP-2 and MMP-9 by immunoprecipitation with specific antibodies. The eletrophoretic bands were scanned and the transmittance values were analyzed with the Sigmagel software (Sigma). RESULTS: ZnSO4 was a strong inhibitor of MMP-2 (I50 = 15 microM) and MMP-9 (I50 = 40 microM), whereas CuSO4, HgSO4 and SnCl2 showed less efficient inhibition potential. SIGNIFICANCE: Our findings show that the activity of oral tissue MMPs may be modulated by metal ions present in the oral environment. Therefore, the accumulation of metals in connective tissue may interfere with the formation and resorption of the extracellular matrix components.

Adult↗
PubMed2000

Fluoride effect on the activity of enamel matrix proteinases in vitro.

Dental fluorosis is common in individuals exposed to different sources of fluoride during tooth development. The mechanism causing this enamel defect is still unknown. Enamel matrix proteinases play a central role in the maturation of dental enamel, and inhibition of these enzymes by fluoride has been one explanation for dental fluorosis. We have investigated the effect of fluoride on the activity of enamel matrix proteinases using a colorimetric assay, casein zymography, and an enamel protein degradation assay. Fluoride (625 microM to 10 mM) inhibited neither the enzymatic activity of the crude matrix extract nor the activity of individual enamel enzymes separated by SDS-PAGE. The proposition that fluoride could directly inhibit enzymes was not confirmed in this study.

Analysis of Variance↗
PubMed2000

Effect of lead, cadmium and zinc on the activity of enamel matrix proteinases in vitro.

Environmental contamination with heavy metals leads to their uptake by the body. Dental tissues are known to harbor metals in concentrations related to the exposure at the time of dentin or enamel formation. Several enzymes involved in the metabolism of extracellular matrix components have been shown to be inhibited by excess metal ions. Enamel matrix proteinases seem to play a central role in the maturation of dental enamel, and inhibition of these enzymes by metals could interfere with amelogenesis. We have investigated the effect of lead, cadmium and zinc on the activity of enamel matrix proteinases using a colorimetric assay, casein and gelatin zymography, and an assay of enamel protein degradation in vitro. All three metals inhibited the proteolysis, as shown by the three methods employed, in concentrations as low as 110 microM. This study showed that contaminant metals can inhibit proteinolysis when a crude enamel extract containing enamel proteases is tested in vitro. Therefore, the presence of heavy metals in enamel matrix could interfere with amelogenesis due to alteration in normal proteolysis.

Amelogenesis↗
PubMed1994

Targeted development of microsatellite markers from inter-Alu amplification of YAC clones.

Primary genetic maps based on highly informative markers are now available. The local density of these markers may, however, not be sufficient. There is thus a need for new means to generate polymorphic markers from targeted regions of the genome. This can be achieved by selectively cloning and sequencing (CA)n-positive human inter-Alu sequences from targeted YAC clones. This method was tested on 21 YACs and led to the development of seven new polymorphic microsatellite markers.

Base Sequence↗
PubMed1994

Mapping of a chromosome 15 region involved in limb girdle muscular dystrophy.

A gene responsible for an autosomal recessive form of limb girdle muscular dystrophy (LGMD2, MIM number 253600) has been localized on chromosome 15. After genotyping additional markers of this chromosome, two were found to flank the disease locus within an interval that was assessed as 7 centiMorgans. The screening of the CEPH YAC libraries with the corresponding probes allowed the isolation of YACs which were used in fluorescence in situ hybridization to define the LGMD2 cytogenetic interval as 15q15.1-15q21.1. Four different approaches were pursued for the establishment of the physical map of this area which allowed the assembly of an uninterrupted YAC contig spanning an estimated 10-12 megabases, with an average STS resolution of 140 kb or for the 25 polymorphic microsatellites on this map, of 400 kb. Twelve genes and 25 genetic markers were positioned in this contig, which is constituted of a minimum of 10 clones.

Chromosome Mapping↗