PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “DNA, BACTERIAL”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 271 records · Page 15Linked to original sources
PubMed2002

Detection and identification of bacterial DNA in patients with cirrhosis and culture-negative, nonneutrocytic ascites.

The current pathogenic theory of spontaneous bacterial peritonitis (SBP) in patients with cirrhosis and ascites suggests that repeated episodes of bacterial translocation (BT) from intestinal lumen to mesenteric lymph nodes followed by systemic seeding are the key steps for the final development of infectious events. However, most of the episodes of systemic bacterial circulation remain undetected. Therefore, we investigated the hypothetical presence of bacteria in blood and/or ascitic fluid (AF) from patients with cirrhosis and sterile (culture negative) AF by means of bacterial DNA (bactDNA) detection and identification. Twenty-eight consecutively admitted patients with cirrhosis and presence of AF were included in the study. BactDNA was detected using a polymerase chain reaction (PCR)-based method. The corresponding bacteria were identified by nucleotide sequencing of purified PCR products. BactDNA was detected simultaneously in blood and AF in 9 patients (32.1%). DNA sequencing allowed the identification of Escherichia coli (n = 7) and Staphylococcus aureus (n = 2). In all cases, the similarity between the sequence found in AF and blood indicated that the bactDNA present in both locations originated from a single clone (single translocation event). Child-Pugh score and basic hemodynamic, clinical, endoscopic, and biochemical characteristics were similar among patients with or without the presence of bactDNA. In conclusion, we have detected bactDNA in serum and AF in 32% of all patients studied, and this likely represents single clone episodes of translocation and systemic seeding. E. coli is the most frequently identified bacteria.

Adult↗
PubMed1976

Identification and study of species specificity of antiphage lipopolysaccharides found in the preparations of bacterial DNA.

A method of isolation of the antiphage agent found in the preparations of bacterial DNA was developed. Chemical analysis of the preparations has shown that according to their qualitative and quantitative composition they are identical to the lipopolysaccharide of the bacterial membrane. On the basis of data on the antiphage activity of the D-LPS from E. coli B and E. coli K12 and on the basis of presumed analogy between the inactivation of the phage by the D-LPS preparations and the phage -- cell interaction it is believed that different parts of the LPS serve as receptors for the phages T7 and T4: O-specific polysaccharide for T4 and core LPS for T7. On the basis of data on the activity of D-LPS of two species of the genus Aerobacter against the phage T7 it is presumed that Aerobacer and Escherichia are related according to the structure of their core LPS.

Coliphages↗
PubMed1976

Identification and study of species specificity of antiphage lipopolysaccharides found in the preparations of bacterial DNA.

A method of isolation of the antiphage agent found in the preparations of bacterial DNA was developed. Chemical analysis of the preparations has shown that according to their qualitative and quantitative composition they are identical to the lipopolysaccharide of the bacterial membrane. On the basis of data on the antiphage activity of the D-LPS from E. coli B and E. coli K12 and on the basis of presumed analogy between the inactivation of the phage by the D-LPS preparations and the phage--cell interaction it is believed that different parts of the LPS serve as receptors for the phages T7 and T4: O-specific polysaccharide for T4 and core LPS for T7. On the basis of data on the activity of D-LPS of two species of the genus Aerobacter against the phage T7 it is presumed that Aerobacer and Escherichia are related according to the structure of their core LPS.

Antiviral Agents↗
PubMed1989

Non-isotopic hybridization assays for bacterial DNA samples.

The background problem associated with the use of streptavidin in detecting biotin-labelled probes hybridized to DNA in crude bacterial extracts has been investigated. We have found that streptavidin binds specifically to a limited number of polypeptides which are difficult to remove by rapid extraction processes. Altering the hybridization and detection protocols results in a marked but not complete reduction of non-specific background in streptavidin-biotin assays. Complete elimination of non-specific background was achieved only when streptavidin was replaced with antibodies for the detection of biotinylated or sulphone-modified probes. The antibody-sulphone and streptavidin-biotin dot blot assays described here require 4.5-5 hours to perform and can detect DNA sequences in samples extracted from 2 x 10(7) cells or fewer.

Bacterial Proteins↗
PubMed1992

Control of bacterial DNA supercoiling.

Two DNA topoisomerases control the level of negative supercoiling in bacterial cells. DNA gyrase introduces supercoils, and DNA topoisomerase I prevents supercoiling from reaching unacceptably high levels. Perturbations of supercoiling are corrected by the substrate preferences of these topoisomerases with respect to DNA topology and by changes in expression of the genes encoding the enzymes. However, supercoiling changes when the growth environment is altered in ways that also affect cellular energetics. The ratio of [ATP] to [ADP], to which gyrase is sensitive, may be involved in the response of supercoiling to growth conditions. Inside cells, supercoiling is partitioned into two components, superhelical tension and restrained supercoils. Shifts in superhelical tension elicited by nicking or by salt shock do not rapidly change the level of restrained supercoiling. However, a steady-state change in supercoiling caused by mutation of topA does alter both tension and restrained supercoils. This communication between the two compartments may play a role in the control of supercoiling.

DNA Topoisomerase IV↗
PubMed1996

IFN-gamma promotes IL-6 and IgM secretion in response to CpG motifs in bacterial DNA and oligodeoxynucleotides.

Lymphocyte recognition of characteristic structural features in microbial DNA may contribute to immune defense by promoting protective immune responses. The dinucleotide CpG is significantly under-represented in vertebrate DNA and is usually methylated. In contrast, CpG dinucleotides are generally present at the expected frequency in bacterial DNA and are unmethylated. These unmethylated CpG motifs induce B cells to secrete IL-6 and IgM, and can induce NK and CD4+ T cells to produce the immunoregulatory Th1 cytokine, IFN-gamma. IFN-gamma inhibits IgM secretion that is triggered by a different bacterial product, LPS. The present study demonstrates that in contrast to its antagonistic interaction with LPS, IFN-gamma causes a dose-dependent increase in the level of IgM secretion induced by CpG DNA. Like IgM secretion, B cell secretion of IL-6 more than doubles after the addition of exogenous IFN-gamma. Mice with disrupted IFN-gamma genes produced less than half as much IL-6 and IgM in response to CpG DNA, supporting the hypothesis that CpG-induced IFN-gamma production contributes to the B cell response. In contrast to its promotion of IL-6 and IgM secretion, IFN-gamma did not significantly affect the spleen cell proliferation activated by CpG motifs. These results indicate that IFN-gamma produced by T and NK cells after CpG DNA stimulation contributes to the B cell production of IL-6 and the subsequent Ig production. These studies provide further evidence that the immune system responds to CpG motifs in bacterial DNA by activating a coordinated set of humoral and cellular responses.

Animals↗
PubMed1998

A standardized protocol for the rapid preparation of bacterial DNA for pulsed-field gel electrophoresis.

A rapid method for the preparation of bacterial DNA for pulsed-field gel electrophoresis was developed for Gram-positive and Gram-negative bacteria. This method was accomplished by reducing the time for the cell lysis reaction, restriction endonuclease digestion, and electrophoresis to 1, 1.5, and 18 h, respectively. The whole procedure from the initial bacterial culture plate to the final analysis of restriction fragments can be completed within 24 h. This rapid method was successfully achieved for Staphylococcus aureus, Enterococcus faecalis, Neisseria gonorrhoeae, Salmonella typhimurium, Serratia marcescens, and Stenotrophomonas maltophilia.

Bacteriological Techniques↗
PubMed1986

Screening pesticides for their ability to damage bacterial DNA.

Twenty-six pesticides and pesticide degradation products were screened (125 micrograms - 2000 micrograms) for their ability to induce unrepairable damage to bacterial DNA. Three repair test systems were utilized in this study, the Salmonella typhimurium (TA1538/TA1978), the E. coli K-12 (Pol A1+/Pol1-) and the E. coli WP2 (WP2, WP2uvrA, WP67, CM611 and CM571). Aldicarb (1000 micrograms), benomyl (250 micrograms), 2-aminobenzimidazole (2000 micrograms), captan (125 micrograms), fenazalor (500 micrograms), 5,6-dichloro-2-trifluoromethylbenzimidazole (NC-2983) (250 micrograms), isothymol (250 micrograms), maleic hydrazide (1000 micrograms), pentachloronitrobenzene (1000 micrograms) were DNA-damaging to one or more bacterial test systems. Isothymol and NC-2983 affected all three test systems. Chlorinated hydrocarbon insecticides, some being recognized as carcinogens, did not produce a zone of inhibition in any of the tester strains possibly due to their poor solubility and diffusion in the agar overlay. It was concluded that these tests can be performed along with bacterial reversion tests to complement each other as short-term screening tests for potential carcinogens and mutagens.

DNA Damage↗
PubMed1983

[Presence in the composition of bacterial DNA of covalently bound RNA fragments].

The nucleotide composition of chromosome and plasmid DNA free of hybrid RNA isolated from resting Escherichia coli cells preliminary cultivated with the help of [14C] uracil has been studied. It has been established that DNA contains [14C]uracil side by side with adenine, thymine, guanine and cytosine. It confirms the presence of RNA fragments in the composition of bacterial DNA which are connected with it covalently.

Bacillus subtilis↗
PubMed1999

Analysis of the Kveim-Siltzbach test reagent for bacterial DNA.

The sarcoid spleen-derived reagent for the Kveim-Siltzbach test (KST) elicits a sarcoid-specific, granulomatous, cutaneous response used to establish the diagnosis of sarcoidosis. In the context of the ongoing discussion of a bacterial cause of sarcoidosis we asked the question whether bacterial DNA could be found in the KST reagent. For this purpose two different KST reagents, an identical preparation from a normal spleen, and a native sarcoid spleen were analyzed by polymerase chain reaction (PCR) employing universal primers detecting conserved DNA sequences coding for bacterial ribosomal 16S RNA. Neither KST reagents, the control preparation, nor the spleen yielded a positive signal, indicating that the preparations are free of bacterial contamination. Because the KST reagent elicits granuloma, these results do not support the hypothesis of a bacterial cause of sarcoid granuloma.

Conserved Sequence↗
PubMedDate not supplied

[The use of random amplification of polymorphous bacterial DNA for the typing of bacteria in the genus Citrobacter].

To obtain the profiles of randomly amplified DNA, isolated from bacteria of the genus Citrobacter, the method of polymerase chain reaction was used. Nine oligonucleotides were evaluated for the possibility of their use as primers for the amplification of random polymorphous sequences of DNA; of these, 2 oligonucleotides which generated profiles, sufficiently reproducible and typical for different C. freundii and C. diversus strains, were selected. The possibility of using the above oligonucleotides in pair for amplification of species-specific fragments of polymorphous bacterial DNA for typing was shown.

Base Sequence↗
PubMed2003

Identification of mixed bacterial DNA contamination in broad-range PCR amplification of 16S rDNA V1 and V3 variable regions by pyrosequencing of cloned amplicons.

Using a sensitive and rapid method combining broad-range PCR amplification of bacterial 16S rDNA fragments and pyrosequencing for detection, identification and typing, we have found contaminating bacterial DNA in our reagents used for PCR. Identified bacteria are the water-borne bacterial genera Pseudomonas, Stenotrophomonas, Xanthomonas, Ralstonia and Bacillus. Our results are in concordance with recent reports of contaminated industrial water systems. In light of this conclusion, we believe that there is a need for increased awareness of possible contamination in uncertified widely used molecular biology reagents, including ultra-pure water. Since sequence-based 16S rDNA techniques are used in a variety of settings for bacterial typing and the characterization of microbial communities, we feel that future certification of molecular biology reagents, as free of nucleic acids, would be advantageous.

Bacteria↗
PubMed2003

Antitumor therapy with bacterial DNA and toxin: complete regression of established tumor induced by liposomal CpG oligodeoxynucleotides plus interleukin-13 cytotoxin.

Despite urgent need, no single strategy has been widely effective at controlling the growth of rapidly progressive solid tumors. We demonstrate here a potent antitumor therapy using modified bacterial DNA and toxin. Treatment of human head and neck cancer established as xenografts in athymic mice with immunostimulatory CpG oligodeoxynucleotides encapsulated in sterically stabilized cationic liposome [(CpG ODN)(SSCL)] and recombinant interleukin-13 Pseudomonas exotoxin (IL13-PE) significantly reduced the tumor growth followed by complete regression in most animals. The antitumor activity of (CpG ODN)(SSCL) was dependent on natural killer cells that infiltrated within tumors. Interestingly, IL13-PE enhanced (CpG ODN)(SSCL)-induced natural killer cell activity and cytokine production in vivo and in vitro. These data strongly suggest that a combination of innate immune activation by (CpG ODN)(SSCL) and tumor-directed targeting by IL13-PE is a novel approach for human cancer immunotherapy.

Animals↗
PubMed1996

Modulation of renal disease in autoimmune NZB/NZW mice by immunization with bacterial DNA.

Preautoimmune New Zealand Black/White (NZB/NZW) mice immunized with Escherichia coli (EC) double standard (ds) DNA produce antibodies that bind mammalian dsDNA and display specificities similar to spontaneous lupus anti-DNA. Since calf thymus (CT) dsDNA fails to induce these antibodies, these results suggest a special potency of foreign DNA in inducing serological manifestations of lupus in a susceptible host. To assess the effects of DNA immunization on clinical manifestations in NZB/NZW mice, we measured renal disease and survival of mice immunized with either (a) EC dsDNA as complexes with methylated bovine serum albumin (mBSA) in adjuvant; (b) CT dsDNA with mBSA in adjuvant; (c)mBSA alone in adjuvant; or (d) unimmunized. After immunization with EC dsDNA, NZB/NZW mice developed significant levels of anti-dsDNA antibodies. Nevertheless, these mice had less proteinuria, nitrate/nitrite excretion, and glomerular pathology than mice immunized with either mBSA alone, CT dsDNA/mBSA complexes, or unimmunized mice. Survival of the EC dsDNA immunized mice was significantly increased compared with the other mice. Furthermore, immunization of mice after the onset of anti-DNA production and proteinuria stabilized nephritis and prolonged survival. The improvement in renal disease occurred despite the expression of autoantibodies that bound mammalian dsDNA as well as glomerular antigens. These results suggest that bacterial DNA has immunological properties that attenuate murine lupus despite the induction of pathogenic antibodies.

Animals↗
PubMed2000

[Detection of bacterial DNA in blood with three pairs of primers].

OBJECTIVE: To develop a stable and sensitive method to detect gut-derived bacterial DNA present in the blood. METHODS: Blood culture and PCR were performed simultaneously when temperature of patients (n = 23) was higher than 38.5 degrees C after laparotomy. PCR was performed after DNA extraction, target genes being beta-lactosidase gene of Escherichia coli(E. coli), glutamine synthase gene of Bacteroides Fragilitas, and 16SrRNA gene of most pathogenic bacteria. DNA of standard strains of E. coli and Bacteroides Fragilitas served as positive controls, blank control as negative controls, and healthy volunteers (n = 20) served as normal controls. We performed PCR twice with part of the samples (n = 20) in order to test the repetition of this method. RESULTS: The repetition rate of PCR was 95%. Three of blood cultures were positive (13.0%, 3/23), the corresponding positive ratio of PCR was 43.5% (10/23) which was higher than that of the blood culture (P = 0.016). CONCLUSION: PCR is more sensitive than blood culture in detection of bacteremia.

Bacterial Translocation↗