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Biomedical subjects

G Bukholm

Publications and source records attributed to G Bukholm.

At least 37 records · Page 2Linked to original sources
PubMed1993

Microinjection of HEp-2 cells with coxsackie B1 virus RNA enhances invasiveness of Shigella flexneri only after prestimulation with UV-inactivated virus.

Coxsackie B1 virus induces increased susceptibility to invasion by Shigella flexneri when HEp-2 cells are inoculated with the complete virus. When RNA from the same virus was microinjected into cells, virus RNA was synthesized and new virus particles were formed, but the transfected RNA had no effect on bacterial invasiveness. However, when the cells were prestimulated with UV-inactivated virus, the microinjected RNA induced an additional enhancement of bacterial invasiveness. Microinjected whole virus particles did not replicate and did not induce any change in bacterial invasiveness. The results indicate that an initial event in virus multiplication is necessary to achieve an effect of transfected viral RNA on invasion of S. flexneri.

Cytosol↗
PubMed1992

Coxsackie B1 virus-induced changes in cell membrane-associated functions are not responsible for altered sensitivity to bacterial invasiveness.

To analyze the possible mechanisms by which coxsackie B1 virus infection affects the invasiveness of Shigella flexneri, we have studied the influence of intracellular levels of Na+ and K+, ATPase activity, cytoplasmic membrane potential, cAMP level and cell communication through gap junctions. 3h after adsorption of viable or UV-inactivated coxsackie B1 virus the Na(+)-K+ gradient of the cell collapsed, ATPase activity decreased, the cytoplasmic membranic potential-dependent tetraphosphonium ion uptake were reduced. No changes in cAMP or intercellular cell communication were observed. S. flexneri invasiveness in HEp-2 cell pretreated with viable or UV-inactivated coxsackie B 1 virus was enhanced, but bacterial invasiveness was unchanged in K(+)-depleted HEp-2 cells, cell cultures with high intracellular Na+ content or ouabain pre-treated cells compared to control cells. We found no correlation between the enhanced bacterial invasiveness in the early phase of coxsackie B 1 virus infection in HEp-2 cell cultures and intracellular K+ depletion, high intracellular Na+ content, inhibited Na(+)-K+ ATPase activity or membranic depolarization.

Cell Communication↗
PubMed1992

Correlation between Coxsackie B1 virus replication and enhanced invasiveness of Shigella flexneri.

Coxsackie B1 virus infection enhances the susceptibility of cultured HEp-2 cells to Shigella flexneri invasiveness. This can be reproduced partially with UV-inactivated virus, particularly the effect observed shortly after viral inoculation. The following phases of viral multiplication were correlated with the enhancing effect: uncoating of viral particles, synthesis of viral RNA and proteins, and assembly of newly produced virus particles. Uncoating of virus particles was completed within 60 min. This process was not correlated with the development of the early effect on invasiveness. Intact virus capsids seem to be necessary to enhance bacterial invasiveness in the early phase of virus infection. Separated capsid proteins had no effect either when applied to the cell surface or when microinjected into the cells. Virus protein synthesis was not required for the virus effect on bacterial invasiveness in the early infection phase, but it seems to be necessary in the late phase.

Cells, Cultured↗
PubMed1991

[Diagnosis of cytomegalovirus infections in hospitalized patients].

Rapid detection of cytomegalovirus (CMV) infections, especially in immunocompromised patients, is important and sometimes lifesaving. We describe one year's experience of using a combination of several methods: detection of "immediate early" CMV antigen in blood, detection of "early" virus antigen after brief incubation in cell culture, detection of viral DNA by polymerase chain reaction, regular culture in human embryo fibroblasts, and serological detection of IgM and IgG antibodies. A quick and early diagnosis was achieved by all three rapid methods. However, none of the methods is sufficiently sensitive or specific to allow it to be used alone. A combination of several methods is recommended in order to achieve maximum efficiency and safety.

Cytomegalovirus Infections↗
PubMed1991

Microinjected Coxsackie B1 virus does not replicate in HEp-2 cells.

Coxsackie B1 virus did not replicate when microinjected into HEp-2 cells. Replication was assayed by production of infectious virus particles, synthesis of viral RNA, and lysis of cells. The same virus preparation initiated replication when it was inoculated into HEp-2 cells similarly to that by microinjected purified coxsackie B1 virus RNA.

Cell Death↗
PubMed1991

Sampling efficiency in the diagnosis of Helicobacter pylori infection and chronic active gastritis.

The methods and sampling procedures used in the diagnosis of Helicobacter pylori infection and chronic active gastritis were evaluated. Five biopsy specimens for bacteriological cultivation and three specimens for histological examination were obtained endoscopically from a defined area of the gastric antral mucosae of 83 patients. An increase in the number of biopsy specimens for cultivation from one to five revealed only one more H. pylori-infected patient. H. pylori was isolated from 31 of 83 patients. Three technically adequate samples for histological examination were obtained from each of 74 patients. Of these 74 patients, chronic active gastritis was diagnosed by demonstration of typical histological changes in all three specimens from each of 20 patients, in two of three specimens from each of 3 patients, and in one of three specimens from 1 patient. The results indicate that one biopsy specimen is sufficient for the isolation of H. pylori, whereas several specimens may be necessary for the histological diagnosis. Chronic active gastritis was found in four patients not infected with H. pylori; on the other hand, H. pylori was isolated from nine patients who showed no signs of chronic active gastritis in any of three samples.

Adolescent↗
PubMed1990

Interferon treatment reduces endocytosis of virus and facultatively intracellular bacteria in various cell lines.

Previous studies have shown that interferons (IFNs) specifically interact with a number of cells cultured in vitro and reduce the invasiveness of facultatively intracellular bacteria. IFN treatment also reduced the internalization of vesicular stomatitis virus (VSV) in cell cultures. Here we show that the anti-invasive effect of IFN on bacteria is eliminated in an L-cell variant where its effect on the uptake of vesicular stomatitis virus is lost. The data strongly suggest that the anti-invasive effect of IFN is mediated through inhibition of endocytosis.

Animals↗
PubMed1990

Coxsackie B1 virus infection enhances the bacterial invasiveness, the phagocytosis and the membrane permeability in HEp-2 cells.

To analyze the effect of coxsackie B1 virus infection on bacterial invasiveness, phagocytosis and cytoplasma membrane permeability, we have studied invasiveness of Shigella flexneri, unspecific phagocytosis of latex particles and release of the non-metabolizible amino acid, alpha-aminoisobutyric acid (AIB). Virus infection enhanced invasiveness of S. flexneri and phagocytosis of latex beads and increased plasma membrane permeability as measured by release of AIB. The effect on all three functions increased with virus concentration, but the kinetics were different. During the early phase of virus infection there was no difference between the effect on invasiveness, phagocytosis and permeability in cell cultures pretreated with viable or with UV-inactivated virus. However, after 6 h, 5 h and 2 h respectively, there was an increased response in cell cultures pretreated with viable virus compared to cells inoculated with UV-inactivated virus. The results indicate that the virus effect on bacterial invasiveness is a function of several parameters, including phagocytosis and membrane function changes.

Cell Line↗
PubMed1990

Genetic evidence that the yopA gene-encoded Yersinia outer membrane protein Yop1 mediates inhibition of the anti-invasive effect of interferon.

HEp-2 cell monolayers were challenged with genetic variants of Yersinia pseudotuberculosis YPIII(pIB1) and Yersinia enterocolitica W22708(pYL4). Both strains were represented by (i) variants harboring the 70-kilobase virulence plasmid, (ii) their isogenic plasmid-cured derivatives, and (iii) two transposon mutants constructed by insertional inactivation of the plasmid genes encoding outer membrane protein Yop1 and Ca2+ dependency in strains YPIII(pIB1) and W22708(pYL4). When the HEp-2 cells were pretreated with recombinant alpha interferon subtype A, all invasive variants of Y. enterocolitica and Y. pseudotuberculosis, except those variants which expressed Yop1, showed a significantly reduced ability to localize intracellularly. The anti-invasive effect of interferon was abolished when the gene was expressed or when a sterile filtered sonic extract of a Yop1-producing strain was added to the cell cultures. To obtain further evidence of a potential role of Yop1, a DNA fragment encoding Yop1 cloned into the vector pBR322 was used. After introduction of the resultant recombinant plasmid pYMS2 into the plasmid-cured variant YPIII and the Yop1-negative transposon mutant YPIII(pIB102) of Y. pseudotuberculosis, both transformants regained the ability to produce Yop1 and showed complete inhibition of the interferon effect. Moreover, the sterile sonic extract of an Escherichia coli strain, which carried pYMS2, neutralized the anti-invasive effect of interferon. The results provide direct genetic evidence that Yop1 mediates inhibition of the anti-invasive effect of interferon in HEp-2 cell cultures. The results also demonstrated that Yop1 itself reduces the ability of Yersinia spp. to localize intracellularly in HEp-2 cells.

Adhesins, Bacterial↗
PubMed1990

Identification of Haemophilus aphrophilus and Actinobacillus actinomycetemcomitans by DNA-DNA hybridization and genetic transformation.

DNA-DNA hybridization was used to identify clinical isolates as Haemophilus aphrophilus or Actinobacillus actinomycetemcomitans. Some of the isolates were naturally competent for genetic transformation and were also used as DNA recipients for identification of other isolates. The results obtained by hybridization were supported by interstrain-to-intrastrain transformation ratios. Distinction between the closely related species H. aphrophilus and A. actinomycetemcomitans was generally clear-cut by both methods. Distinction of H. aphrophilus and A. actinomycetemcomitans from type and reference strains of a diversity of species in the family Neisseriaceae and other gram-negative species was also demonstrated by both methods. This is the first description of the identification of clinical isolates of H. aphrophilus or A. actinomycetemcomitans by using them as recipients in genetic transformation. The results suggest that this is a reliable system for identification of new clinical isolates belonging to these taxonomic entities.

Actinobacillus↗
PubMed1990

Neisseria meningitidis group B capsular polysaccharide. Bacterial content and release in relation to categories of infection and filtrability of released endotoxin.

A total of 41 Neissera meningitidis isolates were analyzed for capsular polysaccharide (CP) and lipopolysaccharide (LPS) release and filtrability. Twenty-two of these isolates were serogroup B from blood or cerebrospinal fluid of patients, five were group B isolates from healthy throat carriers, and 14 were nongroupable (acapsular) meningococcal isolates from healthy carriers. Filtration of liquid whole-cell cultures through cellulose acetate-nitrate filters resulted in distinctly lower LPS filtrate activity for acapsular than for capsular meningococci (p less than 0.001). On the other hand, when polysulfone membrane filtration was performed, filtrates from acapsular and capsular meningococci contained LPS in similar amounts. These results indicate that LPS-containing particles released from acapsular isolates are larger or more aggregated than corresponding CP- and LPS-containing particles released from capsular isolates. The LPS released from acapsular isolates apparently are more efficiently retained by adsorption to cellulose acetate-nitrate. From the capsular isolates comparatively more CP than LPS appeared to be released, as related to cell-bound amounts. The total amounts of CP and released, filtrable LPS through cellulose acetate-nitrate filters were both relatively low and had similar values for capsular carrier meningococci and systemic isolates from mild meningococcal disease. The amount of CP released and passing this type of membrane was significantly higher for systemic isolates from severe septicemia than from mild meningococcal disease (p = 0.03).

Enzyme-Linked Immunosorbent Assay↗
PubMed1990

A unique plasmid profile characterizing Salmonella enteritidis isolates from patients and employees in a hospital.

Plasmid profiling was used as an epidemiological tool during a period of frequent Salmonella enteritidis infection in a hospital. S. enteritidis was isolated from 22 patients and employees. Isolates from 18 persons harbored one 29 and one 36 megadalton (MDa) plasmid. The 29 MDa plasmid has not been previously described in this species and was not found in 54 control strains of S. enteritidis from other sources. The respective restriction endonuclease digest fragments of the 36 and the 29 MDa plasmids were always identical. This plasmid pattern thus served as a marker for the isolates from the outbreak.

Humans↗
PubMed1989

[Gene technology in medical microbiology--epidemiology and diagnosis].

Genetic approaches have been helpful in investigating the epidemiology of infectious diseases. There are many examples in which analysis of plasmid profiles or restriction endonuclease patterns have been used successfully in epidemiological tracing to identify sources of infection and determine the size of an outbreak. A number of genetic probes are presently commercially available to diagnostic microbiological laboratories. Probes have been developed for detection of virulence factors, antibiotic resistance, and for qualitative and quantitative determination of specific pathogens in clinical samples. This technology is currently in the process of being considerably modified and improved, which has already made it an attractive alternative to conventional methods.

Bacterial Infections↗
PubMed1989

Adhesiveness and invasiveness of staphylococcal species in a cell culture model.

A model was established for the study of adhesiveness and invasiveness of staphylococcal species. Five collection strains from each of the species Staphylococcus aureus, S. epidermidis, and S. saprophyticus and 26 fresh isolates from patients with urinary tract infections were tested for adhesiveness and invasiveness in HEp-2 cell cultures. All the strains of S. saprophyticus were able to invade the cells and localize intracellularly in the cultures, whereas the invasive potential among the strains of S. aureus and S. epidermidis was lower. The number of adhesive bacteria was also highest among the S. saprophyticus strains, whereas S. epidermidis was the least adhesive. The model may be suitable for further study of urinary tract infection strains.

Bacterial Adhesion↗
PubMed1989

Differentiation of some species of Neisseriaceae and other bacterial groups by DNA-DNA hybridization.

DNA-DNA hybridization using total genomic DNA probes may represent a way of differentiating between miscellaneous bacterial species. This was studied with type and reference strains of 20 species in Moraxella, Kingella, and other selected Gram-negative groups. Both radioactive and biotin labelling were employed. Most of the species examined were easily distinguished, such as Moraxella (Branhamella) catarrhalis, M.(B.) ovis, M. atlantae, M. phenylpyruvica, M. osloensis, Neisseria elongata, N. meningitidis, Kingella kingae, K. indologenes, K. dentrificans, Oligella urethralis, Eikenella corrodens, Cardiobacterium hominis, Haemophilus aphrophilus, Actinobacillus actinomycetemcomitans, Gardnerella vaginalis, and DF-2. This reflected the extent of the genetic distances between them as a basis for identification by hybridization. There was some clustering in the Moraxella group. Especially the closely related Moraxella nonliquefaciens, M. lacunata and M. bovis showed strong hybridization affinities. This leads to potential problems in distinguishing these three species from each other by DNA-DNA hybridization with total genomic probes alone.

DNA Probes↗
PubMed1989

DNA-DNA hybridization incompatibility of Campylobacter pylori with other Campylobacter and Wolinella species.

DNA-DNA hybridization in solution was used to characterize 23 human isolates of Campylobacter pylori. The 23 isolates showed DNA affinity with the type strain (NCTC 11637). The relative binding ratios varied between 0.83 and 1. Type strains of C. coli (NCTC 11366), C. jejuni (NCTC 11351), C. laridis (NCTC 11352), C. sputorum subsp. sputorum (ATCC 35980), Wolinella recta (NCTC 11489) and W. succinogenes (ATCC 29543) showed relative binding ratios less than 0.01 compared to the C. pylori type strain. The results suggest that C. pylori is a homogenous taxonomic unit distinctly separated from these other species.

Bacteria↗