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V Bakken

Publications and source records attributed to V Bakken.

At least 19 recordsLinked to original sources
PubMed2004

Expression of the beta-adhesin part of HRgpA in Sprague Dawley rats induces a specific antibody response.

The beta-adhesin part of the Porphyromonas gingivalis W50 (ATCC 53978) protease HRgpA was cloned in an eukaryotic expression vector and expressed in COS-7 cells. The monoclonal antibody MAb (61BG1.3), specific for the hemagglutinating domain of beta-adhesin, recognized the expressed beta-adhesin in the transfected cells both by immunoblot and immunofluorescence. Sprague Dawley rats were immunized intramuscularly with beta-adhesin encoding expression plasmid and expression plasmid without beta-adhesin insert. Skeletal muscle tissue at the site of immunization in the beta-adhesin immunized animals was shown to express this protein. The immunization induced a beta-adhesin-specific antibody response. Sera from the immunized animals were tested for hemagglutination inhibiting activity. Due to high natural inhibiting activity in all rat sera tested, no increased hemagglutination inhibition was detected in sera from the beta-adhesin immunized animals.

Adhesins, Bacterial↗
PubMed2001

A single transition state serves two mechanisms: an ab initio classical trajectory study of the electron transfer and substitution mechanisms in reactions of ketyl radical anions with alkyl halides.

Molecular dynamics has been used to investigate the reaction of a series of ketyl anion radicals and alkyl halides, CH2O(*)(-) + CH3X (X = F, Cl, Br) and NCCHO(*)(-) + CH3Cl. In addition to a floppy outer-sphere transition state which leads directly to ET products, there is a strongly bound transition state that yields both electron transfer (ET) and C-alkylated (SUB(C)) products. This common transition state has significant C-- C bonding and gives ET and SUB(C) products via a bifurcation on a single potential energy surface. Branching ratios have been estimated from ab initio classical trajectory calculations. The SUB(C) products are favored for transition states with short C--C bonds and ET for long C--C bonds. ET reactivity can be observed even at short distances of r(C)(-)(C) = ca. 2.4 A as in the transition state for the reaction NCCHO(*)(-) + CH3Cl. Therefore, the ET/SUB(C) reactivity is entangled over a significant range of the C--C distance. The mechanistic significance of the molecular dynamics study is discussed.

Journal Article↗
PubMed2001

The heat shock response of Fusobacterium nucleatum.

The heat-shock response of the oral Gram-negative bacterium Fusobacterium nucleatum was examined. Different strains of F. nucleatum were grown at 37 C. 42 degrees C and 48 C in the presence of [35S]methionine. Cellular proteins synthesised after shifts to higher temperatures were analysed by SDS-PAGE and autoradiography. Strains ATCC 10953, F1, F3 and Fev1 exhibited heat-shock response, and major proteins were observed at 60, 70 and 90 kDa. but increased protein synthesis was also observed for other proteins. Immunoblot analysis, using a panel of antibodies directed to epitopes on different known heat-shock proteins revealed cross-reactive proteins, indicating homology between Escherichia coli, Mycobacterium leprae and F. nucleatum heat shock proteins.

Autoradiography↗
PubMed2001

Whole blood concentrations of organochlorines as a dose metric for studies of the glaucous gull (Larus hyperboreus).

In order to examine if whole blood concentrations of organochlorines (OCs) is an appropriate dosimetric parameter for use in ecotoxicological studies of free-living birds, a number of incubating glaucous gulls (Larus hyperboreus) were repeatedly sampled within and between subsequent breeding seasons. The wet weight concentrations of selected OCs, differing in persistence and fat solubility, were compared and it was assessed to what extent present concentrations could be predicted from concentrations previously measured in the individuals. There were only a few significant differences in the blood concentrations of the selected OCs within and between seasons. The most persistent compound, polychlorinated biphenyl (PCB)-153, showed a low interindividual variability, and between seasons, 70% of the variance could be explained by the level in the previous year, while changes in body condition and blood lipid percentage were of less importance. For PCB-101, the predictability of the present blood concentration from the previous concentration was lower than for PCB-153, and changes in body condition and blood lipid percentage explained a higher proportion of the variance. The present level of alpha-hexachlorocyclohexane (HCH) could not be predicted from the previous level. Sex did not explain any significant proportion of the variance in OC concentrations when previous level and changes in body mass and blood lipid were included in the statistical models. Thus, for the most persistent OCs, concentration in the blood of incubating glaucous gulls is representative for the interindividual differences over time and whole blood concentrations of OCs appear adequate as a dose metric in ecotoxicological studies.

Animals↗
PubMed1997

Immune responses in mice after gastric and subcutaneous immunization with BCG.

Mucosal immunization can induce immune responses different from those induced by systemic immunization. In this study, murine immune responses were analysed after immunization through gastric and subcutaneous routes with Mycobacterium bovis BCG. The number of circulating cells secreting antigen-specific immunoglobulins (Ig), and the number of gamma interferon (IFN-gamma) secreting cells in spleen-cell cultures after in vitro stimulation with mycobacterial antigens were analysed at the single cell level by the ELISPOT method. Levels of antigen-specific antibodies in sera were determined by ELISA. In the subcutaneously immunized mice the authors found approximately 100 times more splenic cells secreting antigen-specific IgG than in gastrically immunized mice or control mice. Their levels of antigen-specific IgG in sera were 66-6700 times higher than in sera from gastrically immunized mice or control mice. In contrast, the numbers of IFN-gamma producing cells in spleen-cell cultures after in vitro activation with BCG were equally high in the immunized groups of mice, and for both groups higher than in non-immunized controls. Furthermore, IFN-gamma producing cells could be demonstrated in gastrically immunized animals even without in vitro activation. The results demonstrate that gastric immunization with the BCG vaccine can induce a systemic T cell-mediated immune response against mycobacterial antigens.

Animals↗
PubMed1996

Induction of systemic murine B-cell responses by Fusobacterium nucleatum and Porphyromonas gingivalis.

The purpose of this study was to examine the antigenic abilities of Fusobacterium nucleatum strain ATCC 25586 and Porphyromonas gingivalis strain W50 black inbred BALB/cABom mice immunized subcutaneously. Furthermore, we aimed to analyze whether the outer membranes (OM) and whole cells (WC) of F. nucleatum or P. gingivalis had an effect on the levels of antibody response and whether a combination of both could either enhance or suppress the B-cell response. A single-cell assay, solid-phase enzyme-linked immunospot (ELISPOT), was used to analyze the splenic B-cell response (immunoglobulin A (IgA), IgG and IgM). Enzyme-linked immunosorbent assay (ELISA) and immunoblotting were used to verify the specific antibody response in the sera. A statistically significant lower level of spontaneous antibody production was observed in the group immunized with P. gingivalis OM compared with groups immunized with F. nucleatum and saline. The specific antibody titers measured by ELISA indicated that the bacterial preparations were able to induce IgG and IgM response. The preparations containing P. gingivalis OM induced higher humoral response than the preparations containing P. gingivalis WC, but for F. nucleatum such a difference was not observed. The prominent proteins revealed had apparent molecular masses of 40 kDa for F. nucleatum and 115, 55-56 and 43 kDa for P. gingivalis; whereas the immunoreactive proteins were 70, 65 and 40 kDa for mice immunized with F. nucleatum and 115, 55-56, 43 and 33-34 kDa for mice immunized with P. gingivalis. Quantitative analysis of B-cell response at the single cell level with ELISPOT revealed that some component(s) of P. gingivalis OM may have a suppressive ability on splenocytes incubated for a short time.

Animals↗
PubMed1996

Taxonomy, biology, and periodontal aspects of Fusobacterium nucleatum.

The pathogenic potential of Fusobacterium nucleatum and its significance in the development of periodontal diseases, as well as in infections in other organs, have gained new interest for several reasons. First, this bacterium has the potential to be pathogenic because of its number and frequency in periodontal lesions, its production of tissue irritants, its synergism with other bacteria in mixed infections, and its ability to form aggregates with other suspected pathogens in periodontal disease and thus act as a bridge between early and late colonizers on the tooth surface. Second, of the microbial species that are statistically associated with periodontal disease, F. nucleatum is the most common in clinical infections of other body sites. Third, during the past few years, new techniques have made it possible to obtain more information about F. nucleatum on the genetic level, thereby also gaining better knowledge of the structure and functions of the outer membrane proteins (OMPs). OMPs are of great interest with respect to coaggregation, cell nutrition, and antibiotic susceptibility. This review covers what is known to date about F. nucleatum in general, such as taxonomy and biology, with special emphasis on its pathogenic potential. Its possible relationship to other periodontal bacteria in the development of periodontal diseases and the possible roles played by OMPs are considered.

Amino Acid Sequence↗
PubMed1994

Identification of Renibacterium salmoninarum surface proteins by radioiodination.

Surface exposed proteins of Renibacterium salmoninarum were identified by radiolabelling whole bacterial cells with 125I, followed by SDS-PAGE and autoradiography. The most prominent bands had molecular masses of approximately 57 kDa and 22 kDa; in addition, some less intensively labelled bands were detected. Polyclonal sera raised against the 22 kDa protein did not react with the 57 kDa protein. N-terminal amino acid sequence analysis of the purified 22 kDa protein showed no similarity with the sequence of the 57 kDa protein.

Amino Acid Sequence↗
PubMed1994

Heat shock response in Actinobacillus actinomycetemcomitans.

The heat shock response in Actinobacillus actinomycetemcomitans, a capnophilic Gram-negative bacterial species that is implicated in the development of certain forms of periodontitis, was characterized. Different strains of A. actinomycetemcomitans were grown at 37, 42 and 48 degrees C in the presence of 35S-methionine. The bacterial cells were lysed, run on SDS-PAGE and subsequently blotted on nitrocellulose paper. After autoradiography of the blots, several protein bands from the cultures at 42 degrees C showed an increased intensity; major bands were observed at 90, 70, and 60 kDa, but increased protein synthesis was also detected at 54, 28 and 17 kDa. Nitrocellulose blots were also incubated with a panel of monoclonal and polyclonal antibodies directed to epitopes on different heat shock proteins. Strong reactivity was found with several antibodies at the position corresponding to a molecular mass of 60 kDa. The protein is probably the GroEL homologue in A. actinomycetemcomitans, a member of the 'common bacterial antigen' family.

Aggregatibacter actinomycetemcomitans↗
PubMed1994

Comparative detection frequency of 6 putative periodontal pathogens in Sudanese and Norwegian adult periodontitis patients.

Twenty-five sudanese and 18 norwegian adult periodontitis patients were selected to participate in this study. The purpose was to compare cultivation results of Porphyromonas gingivalis, Prevotella intermedia, Actinobacillus actinomycetemcomitans, Fusobacterium nucleatum, and Capnocytophaga species as well as various enteric rods in both populations. In addition, DNA probe analysis was used to identify P. gingivalis, P. intermedia, A. actinomycetemcomitans, F. nucleatum, and Bacteroides forsythus in the Sudanese patients and results were compared with those obtained by cultivation. The paper point technique was used to sample 99 sites in the Sudanese group (4 paper points/site) and 119 sites in the Norwegian patients (3 paper points/site). In the Sudanese subjects, the fourth paper point was used for the DNA probe analysis. The chi-square test and the Wilcoxon signed rank test were used to test for statistically significant differences between Sudanese and Norwegian cultivation results as well as between cultivation and DNA results in the Sudanese group. Cultivation results indicated that the Sudanese subjects had significantly lower prevalence of P. gingivalis, P. intermedia, and F. nucleatum (P < 0.01), significantly higher prevalence of Capnocytophaga species (P < 0.05), and similar prevalence of A. actinomycetemcomitans. Almost all Sudanese subjects tested positive for various enteric rods, while none of the Norwegians did so. The extent to which unrestricted use of antibiotics and transport media influenced the levels of enteric species is not known, however.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Microbial associations of 4 putative periodontal pathogens in Sudanese adult periodontitis patients determined by DNA probe analysis.

The few previous cultivation studies on the in vivo associations between various periodontal microbial species have shown several positive and negative associations. The present investigation utilized DNA probe analysis to examine possible in vivo associations between the periodontal pathogens Porphyromonas gingivalis, Prevotella intermedia, Fusobacterium nucleatum, and Bacteroides forsythus in subgingival plaque samples obtained from 25 Sudanese untreated adult periodontitis patients. The standard paper point technique was used to sample 99 sites with a mean probing depth of 6.8 mm (range 6.0 to 10.0). Microbial associations were determined by detecting the effect of the presence or absence of one species (effector) on the occurrence of the other 3 species (target). The Wilcoxon signed rank test was used to examine variations in occurrence of each target bacteria in the presence or absence of the effector. In addition, the Spearman's rank correlation test was used to assess the relationship between the level of each bacteria to that of the other 3. Results showed bacterial associations with the following effector-on-target effects: F. nucleatum (P < 0.01 Wilcoxon; P < 0.001 Spearman) >> P. gingivalis (P < 0.01 Wilcoxon; P < 0.001 Spearman), and B. forsythus (P < 0.05 Wilcoxon; P < 0.001 Spearman) > P. intermedia (P < 0.01 Spearman). The study demonstrated positive associations between the 4 species investigated, while no neutral or negative associations were revealed. The most striking finding was the effect exerted by F. nucleatum on the colonization of P. intermedia; P. intermedia was never detected in a site unless F. nucleatum was also present.

Adult↗
PubMed1990

Diisopropylfluorophosphate-binding proteins in the outer membrane of Fusobacterium nucleatum: strain variations.

Six strains of Fusobacterium nucleatum were tested for their ability to react with [3H]diisopropylfluorophosphate (DFP), a serine protease inhibitor. Several cytoplasmic proteins were labelled but the strongest labelling was regularly observed in a few outer membrane proteins. The number and the molecular mass of the proteins detected varied according to the strain tested. A 61 kDa protein was labelled in all strains tested, including the two type strains ATCC 10953 and ATCC 25586. A 65 kDa protein was particularly strongly labelled in strains Fev1 and F6.

Bacterial Outer Membrane Proteins↗
PubMed1990

Outer membrane proteins of Actinobacillus actinomycetemcomitans and Haemophilus aphrophilus studied by SDS-PAGE and immunoblotting.

This investigation characterized and compared outer membrane proteins (OMP) of the closely related Actinobacillus actinomycetemcomitans and Haemophilus aphrophilus by means of SDS-PAGE patterns and reactions on immunoblots with rabbit antiserum against A. actinomycetemcomitans FDC Y4. Reactions with serum from a patient with Papillon Lefévre syndrome (PLS), from whom periodontal wild strains of A. actinomycetemcomitans had been isolated, were also studied. OMP were purified with selective solubilization from lyophilized cells of 10 wild and 4 reference strains of A. actinomycetemcomitans and 4 reference strains of H. aphrophilus. OMP profiles from wild and reference strains of A. actinomycetemcomitans were similar while those from A. actinomycetemcomitans and H. aphrophilus differed. The most prominent difference was absence of a heat modifiable protein in H. aphrophilus strains. Immunoblotting revealed strong common antigens in most strains, including a heat modifiable protein with mol wt 34 kDa, as well as a 29 kDa and a 16.5 kDa protein. Treatment with pronase and sodium periodate confirmed the protein nature of the major OMP antigens.

Actinobacillus↗
PubMed1990

Growth conditions and outer membrane proteins of Fusobacterium nucleatum.

Fusobacterium nucleatum strains ATCC 10953, ATCC 25586, F1 F3, F6, and Fev1 were grown in different media. The influence of growth conditions on the outer membrane proteins (OMPs) was analyzed by sodium dodecyl sulfate--polyacrylamide gel electrophoresis (SDS-PAGE). There were no apparent differences in the outer membrane protein profiles when cells in the same phase of growth in various rich media were compared. Differences, however, were observed between early logarithmic phase and stationary phase cells. Thus several proteins were only synthesized during late logarithmic and stationary phase. Synthesis of some of these proteins, in particular a 65K and a 14K protein, seemed to depend on the presence of peptides in the medium. In a complete medium, these proteins were synthesized after depletion of some amino acids, and peptides were then utilized.

Autoradiography↗
PubMed1989

Purification and partial characterization of a major outer-membrane protein of Fusobacterium nucleatum.

The major outer-membrane proteins of 40-41 kDa were identified by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) in Fusobacterium nucleatum strains ATCC 10953, ATCC 25586, F3, F6 and Fev1. The proteins were purified by preparative gel electrophoresis. Their behaviour in gel filtration and gel electrophoresis, their sensitivity to proteolytic enzymes, and their amino acid composition were investigated. The purified proteins were partly sequenced from the N-terminal end. A 36.5 kDa portion was protected against extrinsic proteolytic (trypsin, chymotrypsin or pronase) digestion of whole cells. This polypeptide was isolated and partially sequenced from the N-terminal end. From these data and data from extrinsic iodination it was concluded that the N-terminal end of the protein is probably exposed on the surface of the cell. A database search revealed amino acid sequence similarity in an Ala-Pro-rich region of outer-membrane protein A (OmpA) in other Gram-negative bacteria.

Amino Acid Sequence↗
PubMed1989

Outer membrane proteins as major antigens of Fusobacterium nucleatum.

The immunochemical reactions of rabbit polyclonal antibodies directed to different preparations of Fusobacterium nucleatum i.e, whole cells, peptidoglycan associated proteins, a peptidoglycan-protein complex and a purified 40 kiloDalton (kDa) protein, were investigated on outer membrane preparations of Fusobacterium species and a restricted number of Leptotrichia buccalis after their separation on sodium dodecyl sulphate polyacrylamide gels and electrotransfer to nitrocellulose. All F. nucleatum strains had identical reaction patterns with the immune sera tested. Surface exposed parts of a restricted number of proteins with apparent molecular weights at 70 kDa (a doublet band), 60 kDa, 55 kDa and 40 kDa seemed to be major immunogens. Antigenic related proteins either of identical or slightly deviating electrophoretic mobilities to the 40-kDa protein were observed with the other members of Bacteroidaceae tested. The characteristic 70-kDa protein doublet seemed to be restricted to F. nucleatum although single protein bands of near identical molecular weights belonging to the other species tested also reacted. The data also indicate that the 60-kDa and 55-kDa polypeptides might be present in other species of Fusobacterium.

Animals↗
PubMed1989

Utilization of amino acids and peptides by Fusobacterium nucleatum.

Fusobacterium nucleatum strains ATCC 10953, Fevl, F1, F3, and F6 utilized amino acids, in particular glutamate, histidine, and aspartate were common to all strains. Strain differences were observed in the utilization of threonine, serine, lysine, tyrosine, and methionine, and only strain ATCC 10953 utilized all these amino acids. The glutamate and histidine pools were in all cases fully depleted before the other amino acids were attacked and at the same time all strains except 10953 started to utilize peptides at a noticeable rate. For strain Fevl, glutamyl- and aspartyl-containing peptides seemed to be of considerable nutritional importance, and this strain did not grow on a medium based on amino acids alone. On the other hand, strain 10953 did not utilize any peptides to a noticeable extent, and it could grow on an amino acid based medium.

Amino Acids↗