Profile of proteins complexed with circulating DNA of a lung cancer patient.
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Biomedical subjects
Publications and source records attributed to M da G Carvalho.
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We have verified the presence of line-1 retrotransposon (L1) in plasma DNA in 15/17 brain tumor (glioma) patients and in 6/6 healthy people by applying PCR amplification of part of the L1 5' end. The same samples were separately amplified for K-ras. Results suggested that L1 sequences are circulating throughout the body. We hypothesized the participation of transposable elements such as L1 in a putative DNA release mechanism.
Small amounts of plasma-free DNA have been observed both in healthy individuals and in patients with various diseases such as systemic lupus erythematosus, rheumatoid arthritis, viral hepatitis, and cancer. This communication demonstrates that septic patients also release DNA in plasma. After DNA extraction from plasma, exon 1 of the K-ras gene was amplified by PCR and products were analyzed by dot-blot hybridization. Plasmas from polytraumatic patients and control healthy individuals were used for comparisons with septic patients. Our results show that septic patients present DNA in their plasma. As far as we know, this is the first evidence of circulating DNA in septic patients.
Mayaro virus (alphavirus) infection of Aedes albopictus cells results in inhibition of cell protein synthesis and viral proteins are preferably synthesized. When infected cells are heat shocked, however, there is also an inhibition of viral protein synthesis, and there is preferential synthesis of heat shock proteins. Based on these observations, the distribution of Mayaro viral RNA in polysomes and the association of p34 (capsid protein) with ribosomal fractions of the cells under such conditions have been analyzed. During infection, the viral RNA is mainly observed in light polysomes (60% of total viral RNA in the cell) and also in heavy polysomes (13%). However, when infected cells are heat-shocked, the viral RNA is strongly mobilized from heavy polysomes to the light polysomes fraction and an enrichment in the unbound fraction can be noticed. The amount of p34 associated with the ribosomal fraction was also shown to be decreased in the heat shocked cells. These data lead to the suggestion that two mechanisms could be involved in the inhibition of Mayaro virus protein synthesis in response to heat shock: (1) mobilization of Mayaro virus RNA from heavy to light polysomes; (2) a decrease in the amount of the p34 within the ribosomal fraction.
In total, 86 enterococcal strains including representatives of most of the described species were tested for the ability to agglutinate human, sheep, and rabbit erythrocytes. Five strains did not react with any of the erythrocytes tested, and 81 (94.2%) strains agglutinated only rabbit erythrocytes. The hemagglutination titers ranged from 2 to 64. Loss of the hemagglutination activity was observed when rabbit erythrocytes were treated with trypsin or neuraminidase. Trypsin treatment of the bacterial suspensions also caused loss of the agglutination ability. On the other hand, heat treatment of bacterial suspensions increased the efficiency of the interactions, and higher titers were obtained. Assays for inhibition of hemagglutination were performed with alpha-D-fucose, alpha-D-galactose, beta-D-galactose, D-glucose, N-acetyl-galactosamine, N-acetyl-glucosamine, N-acetylneuraminic acid, N-acetylneuraminic acid-lactose, and fetuin. Only fetuin was able to inhibit the hemagglutination reactions. The results showed that hemagglutination properties are common to the different enterococcal species tested. They also suggest that enterococci possess hemagglutinins of proteic and non-proteic nature that are involved in the attachment to sialic acid-containing receptors on the surface of rabbit erythrocytes.
A total of 330 enterococci strains isolated from several human (272 strains) and animal (27) clinical specimens and environmental sources (31) in Brazil were identified to species level. Major human sources included urine (48.5%), blood (15.8%), and wounds (9.5%). Human isolates were identified as Enterococcus faecalis (90.0%), E. faecium (6.9%), E. gallinarum (1.1%), E. durans (0.8%), E. casseliflavus (0.4%), E. raffinosus (0.4%), and E. mundtii (0.4%). Strains isolated from animals were composed of E. hirae (40.7%), E. faecalis (33.3%), E. faecium (18.5%), and E. casseliflavus (7.5%). Among environmental isolates, 42.0% were E. faecalis, 35.4% E. faecium, 13.0% E. hirae, 6.4% E. casseliflavus, and 3.2% E. durans. Antimicrobial susceptibility tests were performed for 200 strains. Overall, high-level resistance (HLR) to aminoglycosides was found in 66 (33.0%) of the strains tested. HLR to gentamicin was detected in 11.5% of the strains, whereas 19.0% of the strains showed HLR to streptomycin and 26.0% showed HLR to kanamycin. Five (22.7%) of the E. faecium strains were resistant to ampicillin [minimum inhibitory concentration (MIC) > 32 micrograms/ml]. Vancomycin MIC50 and MIC90 were 2 and 4 micrograms/ml, respectively; only eight strains (identified as E. casseliflavus or E. gallinarum) had MIC of 8 micrograms/ml. No beta-lactamase activity was detected by the nitrocefin test.
We addressed the question how temperature elevation inhibits Mayaro virus replication in Aedes albopictus infected cells. The morphology and macromolecular changes induced by temperature, infection and high serum concentration were investigated in these cells. Cells incubated with 2 and 10% serum at 28 degrees C disclosed an intense vacuolization and inhibition of [35S]methionine incorporation in a time-dependent manner. 34 and 50 kDa viral structural proteins were detected 24 h after infection. In contrast, an inhibition of viral proteins synthesis occurred when infected cells were kept at 37 degrees C (heat-shock conditions). Total cellular RNA was isolated from mock and infected cells incubated at 28 or 37 degrees C. Northern blot analysis with a Mayaro genomic probe coding for viral structural proteins showed a decrease in the amount of viral 26S RNA in stressed cells when compared to those kept at 28 degrees C. Taken together, these results suggest that the inhibition of viral proteins synthesis in response to temperature elevation is associated with a decrease in the amount of subgenomic 26S RNA.
Incubation of Aedes albopictus cells infected with Mayaro virus at 37 degrees C causes inhibition of virus replication. During the first hour post infection (p.i.) incubation at 37 degrees C inhibited cellular and virus proteosynthesis. A preferential translation of heat shock proteins 82 kD and 70 kD was observed. After incubations longer than 1 hr at 37 degrees C, a switch to normal pattern of cell protein synthesis occurred without recovery of virus proteosynthesis. In addition, preferential synthesis of three major virus proteins of 62 kD, 50 kD and 34 kD was observed, when infected cells incubated at 37 degrees C were shifted down to 28 degrees C.
We analyzed alterations in CDKN2 in gliomas from an ethically mixed population and correlated the results with patients clinical data. We screened for methylation at CDKN2 and for microsatellite instability (MSI) and loss of heterozygosity (LOH) in the region 9p21-22 using 4 markers. We found: 3/30 (10%) cases with CDKN2-methylated gliomas; an average of 4% of MSI; and 24.5% of LOH in the region 9p21-22. Methylation of CDKN2 was only detected in patients showing high-grade gliomas with short survival. MSI and LOH in the region 9p21-22 were detected in patients showing high-grade gliomas with short survival and in one patient with a recurrent low-grade astrocytoma grade II who died from the disease after 3 years, indicating that such alterations represent poor prognosis.