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Biomedical subjects

A B Dalen

Publications and source records attributed to A B Dalen.

At least 19 recordsLinked to original sources
PubMed2000

Prevalence of GB virus C (also called hepatitis G virus) markers in Norwegian blood donors.

GB virus C (GBV-C), also called hepatitis G virus (HGV), occurs worldwide, but the clinical significance of this virus is still unclear. Plasma samples from 1,001 blood donors were tested by reverse transcription PCR using primers from the NS5 region and by a commercial enzyme-linked immunosorbent assay (ELISA) for the detection of immunoglobulin G antibodies against the putative envelope of HGV (anti-HGV E2). GBV-C/HGV RNA was present in the plasma from 2.5% of the blood donors, and anti-HGV E2 antibodies could be detected in 10.5% of the samples. Only one of the blood donors with viremia had elevated levels of alanine aminotransferase. Among ELISA-positive donors, there was a significantly higher percentage (16.5%) of individuals who had been treated by acupuncture than individuals who had not been given this treatment (9.4%). No other variables showed significant differences. Screening of medical records from 401 recipients of blood from PCR-positive donors revealed no association with liver disease. Four of 12 partners (33%) were HGV RNA positive, and sequence analyses of the strains showed that four of the couples probably were infected with the same strains, while strains from different couples were not identical. Anti-HGV E2 antibodies were detected in serum samples from four other partners. The prevalence of GBV-C/HGV among blood donors in our region is dramatically higher than the prevalence of hepatitis C virus (0.03%).

Adult↗
PubMed1993

A low oncogenic variant of Friend murine leukemia virus with strong immunosuppressive properties.

Friend leukemia complex (FLC) is known to induce immunosuppression but the use of FLC in studies of immune cells function is disadvantageous since the immunosuppression always is accompanied by an acute erythroleukemia. To obtain immunosuppressive variants of FLC with reduced leukemogenic potential, we isolated T-helper cells from FLC infected mice, and passed lysates of the cells to recipient uninfected mice. A group of these mice developed a condition distinct from the disease induced by FLC. A viral stock prepared from these mice, designated Fd-MIV for friend derived murine immunodeficiency virus, induced a profound suppression of the primary antibody response without acute transformation in adult NMRI mice. Terminally a wasting disease with weight loss, atrophy of the thymus and lymph nodes and renal disease was observed in some mice. Analysis of viral DNA and RNA from infected NIH 3T3 cells showed that Fd-MIV contained at least two viral components, a 8.4 kb friend murine leukemia virus (F-MuLV) and a 7.4 kb mink cell focus (MCF)/xenotropic virus related genome. The 7.4 kb genome was not detected in Fd-MIV infected, immunocompromised mice indicating that the 8.4 kb genome might be responsible for the disease.

Animals↗
PubMed1993

Polyclonal activation of B-lymphocytes and induction of autoimmunity in retrovirus infected NMRI mice.

Polyclonal activation of B-lymphocytes accompanies many retroviral infections. Friend derived murine immunosuppressive virus (Fd-MIV) is a non-defective murine retrovirus which was isolated from T-helper cells from mice infected with the acute transforming retrovirus Friend leukaemia complex (FLC). In contrast to FLC, Fd-MIV does not induce acute transformation of lymphoid and erythroid cells but causes immunosuppression and lymphadenopathy in adult NMRI mice. The effect of Fd-MIV infection on B-lymphocytes was studied. Fd-MIV infection led to a persistent hypergammaglobulinemy with a significant increase in the level of circulating IgG, IgM and immune complexes. In the spleen and lymph nodes, B-lymphocyte proliferation was found. Parallel to the development of hypergammaglobulinemy, autoantibodies to a variety of nuclear and other autoantigens was detected. In conclusion, the Fd-MIV infection leads to a B-lymphocyte dysfunction that has many parallels with AIDS. Furthermore, the Fd-MIV infection seems to represent an example of an autoimmune condition caused by an exogenous infectious agent.

Animals↗
PubMed1985

Isolation of an acidic polysaccharide antigen from Propionibacterium acnes.

An acidic polysaccharide antigen is released from Propionibacterium acnes I and II during growth. The molecular weight of the antigen was heterogeneous and when fractionated on a Sepharose CL-6B column, the antigen was detected at Kav values of between 0.1 and 1.0. The pI of the antigen was below 3.5. Rabbit antiserum raised against purified acidic-polysaccharide agglutinated P. acnes showing that the polysaccharide was a surface antigen. Human antibodies towards whole P. acnes-II organisms were quantitated by an agglutination technique, and antibodies towards purified acidic polysaccharide were quantitated by single radial immunodiffusion. A high prevalence of antibodies against whole bacteria and the acidic polysaccharide was found in sera from healthy individuals. The antibody titre in sera from acne patients was significantly higher than that in sera from blood donors.

Acne Vulgaris↗
PubMed1985

Rabbit antibodies against the major internal protein of a retrovirus-like particle bind to epidermal cells in psoriatic skin. Brief report.

A rabbit antiserum against the major internal protein, p27, of a psoriasis associated retrovirus-like particle has been used in indirect fluorescence microscopy of biopsies from psoriatic skin. The analysis indicate expression of p27 antigen in epithelial cells in psoriatic lesions and in clinically uninvolved psoriatic skin. A reaction of the antiserum with dermal vessel walls in the lesion was also observed.

Animals↗
PubMed1985

The major internal protein, p27, of a retrovirus-like particle is expressed in blood lymphocytes from psoriatic patients.

Retrovirus-like particles were isolated from the urine of a patient with psoriasis. The major internal protein, p27, in these particles was isolated by immunosorbent chromatography and gel filtration on a Sephacryl S-300 column in 6 M guanidine hydrochloride. The protein was purified to homogeneity as judged by SDS-PAGE. A hyperimmune serum with specificity for p27 was obtained by vaccination of a rabbit with purified p27 antigen. This antiserum was used to examine blood lymphocytes for the expression of p27 antigen by indirect immunofluorescence. Between 0.1 and 1 per cent of the lymphocytes obtained from patients with psoriasis showed a bright cytoplasmatic (and membrane) fluorescence while no p27 positive cells could be detected in the preparations from the healthy controls (frequency less than 0.01 per cent). Among the p27 positive psoriatic cells were lymphocytes with markers for T cells, B cells and NK cells.

Animals↗
PubMed1984

Preparative isolation of immune complexes from serum by sucrose gradient ultracentrifugation.

Immune complexes were isolated by ultracentrifugation in sucrose gradients (20-65% (w/w]. the centrifugation procedure was demonstrated to be isopycnic. The banding density of the complexes was influenced by the chemical nature and molecular size of the antigen and by the antigen to antibody ratio. The method was applied for preparative isolation of immune complexes from patients with systemic lupus erythematosus, rheumatoid arthritis, ankylosing spondylitis, psoriatic arthritis, and uncomplicated psoriasis.

Antigen-Antibody Complex↗
PubMed1983

A virus-like particle associated with psoriasis.

Virus-like particles were demonstrated by electron microscopy of specimens from psoriatic plaques. Cell cultures established from plaques released particles, showing the morphological features of a retrovirus, for a prolonged period. The particles had a buoyant density of 1.17 g/cc and contained a surface protein of Mr 70,000 which bound to concanavalin A and therefore probably was of glycoprotein nature. A major internal protein of Mr 30,000 and two minor proteins of Mr 18,000 and 15,000 were detected. The composition of the proteins therefore resembled that of murine C-type retrovirus. Patients with psoriasis release virus-like particles in their urine which have a different morphology to the particles from cell cultures. A similar difference could be observed in particles from cell cultures after treatment with normal urine. Patients with psoriatic arthritis had serum immune complexes. The complexes contained distorted particles which could not be identified as virions on a morphological basis. A radio immunoassay was performed which demonstrated common antigens in the virus-like particles isolated from psoriatic urines, immune complexes and cell cultures.

Adult↗
PubMed1983

Urine proteins cross-reacting with antiserum against virus-like particles from cultured psoriatic epithelial cells.

Subcellular particles resembling enveloped viruses were isolated from the urine of a psoriatic male. The particles were located at densities between 1.15 and 1.18 g/cc after sucrose gradient centrifugation. The fraction containing purified particles possessed proteins that cross-reacted with an antiserum raised against virus-like particles from a cell culture established from a psoriatic lesion. Analysis of the cross-reacting antigens by concanavalin A fractionation and SDS-PAGE revealed a glycoprotein with Mr 70,000 (gp70) and three smaller molecules with apparent molecular weights of 30,000, 18,000, and 15,000, respectively. These values were identical to those obtained for the virus-like particles isolated from the cell culture with an envelope glycoprotein with molecular weight of 70,000 and three inner proteins. Estimation of the molecular weights for the three smaller molecules by gel filtration in 6M guanidine-hydrochloride gave Mr 27,000, 15,000, and 12,000, respectively, for the three proteins. The designations p27 p15, and p12 are based on the molecular weight estimation by the chromatographic method.

Antigens, Viral↗
PubMed1983

Characterization of virus-like particles from a psoriatic patient with respect to the possible presence of particle-associated RNA and RNA-directed DNA polymerase.

Subcellular particles resembling retroviruses with respect to their morphology, density, and protein composition, and which are present in the urine of a psoriatic patient have been analysed for the presence of high-molecular-weight polyadenylated RNA and RNA-directed DNA polymerase activity. Neither RNA-directed DNA polymerase activity nor high-molecular-weight polyadenylated RNA was detected in preparations containing the purified virus-like particles. This was the case even when the amount of particles analysed exceeded by a factor of 50 or more the amount of avian myeloblastosis virus in which both polymerase activity and RNA were detected.

Humans↗
PubMed1977

The use of homocarnosine as a spacer in indirect haemagglutination.

Homocarnosine (gamma-butyryl-L-histidine) was bound to erythrocytes through the action of glutaraldehyde in order to increase the number of available groups for diazotization on the surface of the cells. Diazotization was performed with tetrazotizized di-o-anisidine (TOD). TOD decomposed rapidly at an alkaline pH. The reagent was stabilized by the use of borate buffers. The presence of homocarnosine on erythrocytes enhanced the coupling of histidine by diazotization. TOD formed bonds of varying lability with alifatic amino and imino groups. This inhibited completely the formation of stable bonds with histidine and tyrosine. The relative amounts of stable bonds formed by TOD and human serum albumin and TOD and gamma-globulin varied inversely with the concentration of the proteins. The two proteins were used as model antigens and the presence of homocarnosine on the surface of the erythrocytes increased the sensitivity of the haemagglutination reaction by a factor of 4-8.

Amino Acids↗
PubMed1976

The effect of glutaraldehyde on the stability of erythrocytes and on virus receptor substances.

Fixation with glutaraldehyde at a concentration above 0.05 per cent for 1 h at neutrality rendered erythrocytes resistant towards surfactants as Triton X-100, Tween-80 and sodium dodecyl sulphate. Fixation of erythrocytes with low concentrations of glutaraldehyde abolished the lytic effect of membrane active proteins as complement, phospholipase C and staphylococcal alpha-toxin. The fixation procedure did not alter significantly the receptor groups on erythocytes for viruses of the ortho- and para-myxo group and rubella virus. The fixation reduced the agglutinability of human O-erythrocytes by reovirus.

Aldehydes↗
PubMed1976

Proteolytic degradation of staphylococcal alpha-toxin.

Staphylococcal alpha-toxin of mol.wt. 39,000 was degraded at an alkaline pH by staphylococcal extracellular proteases resulting in the formation of three relatively stable intermediates with mol.wt. 27,500, 23,500 and 12,000. The intermediate with mol.wt. 27,500 which existed in two charged forms, was isolated by column chromatography and found to be non-haemolytic. Furthermore, it could be obtained by proteolysis of alpha-toxin (mol.wt. 39,000) with chymotrypsin in low concentrations. This intermediate was further degraded by trypsin to the protein with mol.wt. 23,500 and 12,000.

Alkalies↗
PubMed1976

A simple procedure for the purification of staphylococcal alpha-toxin.

Staphylococcal alpha-toxin was produced in a fluid medium based on acid hydrolysed casein using strain Wood 46. alpha-Toxin and several other proteins were precipitated from bacteria-free culture supernatants by heating at 60 degrees C for 20 min. The process was influenced by the pH of the solution. The toxin was completely inactivated and the precipitate contained a number of proteins if the pH of the solution was adjusted to 4.0-5.0. Heat precipitation of solutions having a pH of 6.0-7.0 resulted in a partial inactivation of alpha-toxin. The precipitates at this pH contained less of the additional proteins and had higher relative amounts of alpha-toxin than precipitates formed at a lower pH. The precipitate was dissolved in 8 M urea with the resultant activation of the haemolysin. Pure alpha-toxin with a molecular weight of 39,000 was obtained by electrophoresis in 8 M urea at pH 8.6 in ordinary tubes for polyacrylamide electrophoresis. The separation time was 45 min. The minor component of alpha-toxin with a pI of 7.4 could be demonstrated by the same method. A non-haemolytic protein with a molecular weight of 27,500 which existed in at least two charged forms, was shown to have an antigenic relationship to the toxin with a molecular weight of 39,000.

Bacterial Toxins↗
PubMed1976

Spontaneous alpha-toxin mutants of Staphylococcus aureus.

Prolonged cultivation of strain Wood 46 in fluid cultures resulted in a selection of mutants with low or no haemolytic activity. In one group of mutants, four out of five strains showed no production of alpha-toxin when examined by polyacrylamide gel electrophoresis and by double diffusion in agar. Two major extracellular proteins which have been identified by other methods as degradation products of alpha-toxin were also absent. The absence of alpha-toxin did not affect growth in fluid or solid media. Fibrinolysin was produced by these mutants but at a much lower rate than by the wild type. A second group of mutants was characterized by a slow rate of growth on rabbit blood agar and showed a heterogeneous extracellular protein pattern. These mutants had a high growth rate in fluid medium consisting of acid hydrolysed proteins. Production of fibrinolysin was absent or low in three out of four mutants in the second group. The slow growth and low production of alpha-haemolysin in rabbit blood agar probably was caused by deficient extracellular proteolytic activity of the mutants.

Bacterial Proteins↗
PubMed1975

Multiple forms of staphylococcal alpha-toxin.

A group of proteins was readily extracted at neutrality from trichloroacetic acid precipitates of staphylococcal culture filtrate supernatants, while alpha-toxin was dissolved and activated by treating the precipitate with 8 M urea, with acidic buffers or by heating to 90-100 degrees C at neutrality. Heat activation of the precipitate produced a relatively pure alpha-toxin with a molecular weight of 39,000. alpha-Toxin was eluted together with three other proteins on hydroxyl apatite chromatography, and evidence was obtained for an association between the four proteins. On isoelectric focusing a haemolytic fraction was obtained at pH 6.2, probably due to acid activation of the precipitate formed at the cathodic end of the column. The alpha-haemolytic fractions with pI's of 7.4 and 8.6 were shown to consist of alpha-toxin only when analyzed by acrylamide electrophoresis in the presence of sodium dodecyl sulphate. The haemolytic component with a pI of 9.2 contained two additional components of molecular weights of 27,500 and 18,000. Chromatography of this material on Sephadex G-200 showed that alpha-toxin and the two proteins appeared as a high molecular complex.

Chromatography, Gel↗