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Biomedical subjects

B Sundquist

Publications and source records attributed to B Sundquist.

At least 37 records · Page 2Linked to original sources
PubMed1984

A non-haemagglutinating isolate of mink enteritis virus.

A virus was isolated from mink showing clinical and pathological signs of mink enteritis. This virus was identified as mink enteritis virus (MEV) from results of serological tests, determination of its density in CsCl (1.415 g cm-3), and morphology, including size (20 nm in diameter). The isolate was designated MEV-S. In contrast to other known MEV strains, the MEV-S isolate has no haemagglutinating (HA) activity with swine red blood cells (RBCs) at 4 degrees C and pH 6.8. Neither was there any HA at other pH values and temperatures, or when horse, bovine and rhesus monkey RBC's were used.

Animals↗
PubMed1983

Assay of detergents by rocket electrophoresis in agarose gels containing red blood cells: "rocket hemolysis".

A method is described for quantitation of charged detergents using their hemolytic property in an electrophoresis assay in agarose gels containing red blood cells. After electrophoresis the zone of hemolysis is directly proportional to the concentration of detergent in the sample. Using this technique we have determined the smallest detectable concentration for the negatively charged detergents, sodium dodecyl sulfate (SDS) and Quil A to about 10 micrograms/ml and 25 micrograms/ml, respectively and the positively charged cetyltrimethylammonium bromide (CTAB) to about 10 micrograms/ml.

Animals↗
PubMed1983

Protein subunit vaccines of parainfluenza type 3 virus: immunogenic effect in lambs and mice.

Protein subunit vaccines were prepared from a mixture of the haemagglutinin (HN) and fusion (F) glycoproteins of parainfluenza type 3 virus (PI-3). The glycoproteins were isolated in three different forms and characterized by their sedimentation coefficients: 30S protein micelles (a complex of several HN and F glycoproteins devoid of detergent and lipid), 18S protein-TX complexes (a complex of several glycoproteins containing the detergent Triton X-100), and 4S protein-TX complexes (probably monomers of the glycoproteins complexed to Triton X-100). These preparations were tested as vaccines in mice and lambs. The immune response in the mice was assayed both in the serum and in extracts from the lungs using an ELISA technique. Both of the multimeric complexes were highly immunogenic. The 30S protein micelles induced a high antibody response after two injections with either 10 or 1 microgram protein. The serum IgG titres reached levels of about 90 micrograms/ml and 40 micrograms/ml respectively. Similar titres were reached with the 18S protein-TX complexes. After two injections of either the 30S or the 18S complexes IgA antibody responses were detected in the lung extracts. The 4S protein-TX complexes were poor immunogens and induced low antibody responses in mice. The lambs were vaccinated with the 30S protein micelles, and the immune response was evaluated serologically and in challenge experiments. The 30S protein micelles in an oil adjuvant induced detectable serum antibody titres as well as protective immunity against the pneumonia caused by the PI-3 virus.

Animals↗
PubMed1983

Production of a feline parvovirusvaccine using monolayer cell systems in roller flasks and microcarriers.

A parvovirus-strain originating from a case of spontaneous panleukopenia has been adapted and propagated in a feline lung fibroblastic cell line. Cultivation of parvovirus infected monolayer cells was carried out in 11 glass flasks containing 50 ml media and on microcarriers in 0.5 - 101 stirring flasks with 0.5-61 media. Harvest of propagated virus from flask monolayer and microcarrier cultures was performed daily for 5 days during one week. The yields of virus antigen per/ml tissue culture media were equal in the two systems, as monitored by hemagglutination and ELISA assays. The seeding and harvesting procedures of virus were found to be simpler with the microcarrier system than with roller flasks. The scaling up is in progress and comparable results have been obtained in 101 scale.

Animals↗
PubMed1981

Goat visna virus: isolation of a retrovirus related to visna virus of sheep.

Choroid plexus (GCP-3) cell cultures were prepared from an adult goat with symptoms of visna. The GCP-3 cell layer had partly fused into large multinucleated giant cells and electronmicrographs showed virus particles morphologically indistinguishable from sheep visna virus (SVV). A virus, designated goat visna virus (GVV), was subsequently purified from the GCP-3 cultures. The virus particles have a density of 1.15 g/ml and a high molecular weight RNA similar in size to that of SVV. A virion-associated DNA polymerase was identified which is stimulated to the same extent as the SVV polymerase by different synthetic RNA and DNA template-primer combinations and which shows the same Mg2+ and Mn2+ stimulation optima. Polypeptide analysis by SDS-PAGE revealed that the virion proteins of GVV and SVV had similar molecular weights. By immunodiffusion tests it was demonstrated that the major internal proteins of GVV and SVV are related. Consequently, we conclude that GVV should be classified as a retrovirus and that it is closely related to visna virus of sheep.

Animals↗
PubMed1979

Phosphonoformate inhibits reverse transcriptase.

The new antiviral substance phosphonoformate (PFA) has been tested in a cell-free system for its effect on reverse transcriptases from an avian retrovirus (avian myeloblastosis virus, AMV) and from mammalian retroviruses (Rauscher leukaemia virus, RMuLV; bovine leukaemia virus; baboon endogenous virus; simian sarcoma virus; visna virus). The observed inhibitory effect of PFA has been compared with that of a structurally related substance, phosphonoacetate (PAA). Phosphonoformate, at a concentration of 100 microM, reduced the activities of all the above mentioned polymerases by 90% when (rA)n.(dT)10 was used as a template/primer. The dose-response curves for AMV and RMuLV polymerases primed with (rA)n.(dT)10 showed PFA to be a 1000-fold more active than PAA; the RMuLV polymerase activity was reduced to 50% after incubation with 0.7 microM-PFA and 0.7 mM-PAA, respectively. There was no difference in PFA inhibition of virus-associated and purified reverse transcriptase activity. Results with various synthetic templates showed that both the RNA- and the DNA-dependent polymerase activities of reverse transcriptase were inhibited by PFA. The endogenous polymerase activity of AMV was inhibited to 50% at 100 microM-PFA, while PAA had no effect. The PFA inhibition was dependent on whether Mg2+ or Mn2+ was used as divalent cation in the assay. Phosphonoformate arrested DNA synthesis immediately after being added to the assay system. The mechanism of inhibition of the AMV polymerase was non-competitive with respect to substrate and template and the apparent inhibition constants were 16 microM and 9 microM, respectively.

Animals↗
PubMed1979

Phosphonoformate inhibition of visna virus replication.

Phosphonoformate (PFA) inhibits multiplication of visna virus in sheep choroid plexus cells; a 50% reduction of virus yield was obtained by 20 to 80 microM PFA. Morphological changes, such as syncytial formation and cell degeneration, could be reversibly prevented by PFA. Cell growth was not significantly affected at 500 microM PFA, although prolonged treatment with 2 mM PFA did arrest cell growth. Cell-free reverse transcriptase activity primed with various synthetic template-primers was inhibited about 90% in the presence of 100 microM PFA. The results from kinetic experiments suggested that reverse transcriptase was utilized early but not late in the infection cycle. A structurally related substance, phosphonoacetate, did not inhibit visna virus multiplication and had no inhibitory effect on reverse transcriptase activity at a concentration of 500 microM.

Animals↗
PubMed1977

Characterization of mRNA-protein complexes from mammalian cells.

In a previous report we described the use of oligo(dT)-cellulose for the isolation of mRNA-protein complexes from EDTA-dissociated polysomes extracted from normally growing or adenovirus infected KB-cells (I). Experiments presented here provide evidence that proteins involved in these complexes bind specifically to mRNA since: a) the proteins and mRNA cosediment through sucrose gradients, b) they adsorb and elute from oligo(dT)-cellulose together, and c) analysis of the products from ribonuclease digestion experiments show that the poly (A) end and a separate small fraction of the mRNA are resistant to the enzymes and attached to protein.

Adenoviridae↗
PubMed1977

Effect of homopolyribonucleotides on messenger ribonucleoprotein particles.

A discrete set of polypeptides copurify with and appear to be specifically attached to mRNA from polysomes of eukaryotic cells. This report describes the effect of homopolyribonucleotides on mRNA-protein complexes separated from ribosome subunits by oligo(dT)-cellulose chromatography. It is shown that poly (U) and poly (A) can release mRNA-protein complexes adsorbed to oligo(dT)-cellulose, whereas poly (C) and poly(I) are much less effective in this process. Analysis of polyribonucleotide released material showed that poly(U) effectively dissociated the mRNA-protein complexes while poly(A) caused no or only partial derangement of these particles. The specificities seen in the polyribonucleotide effects in turn suggest a high degree of specificity in the interaction between the proteins and mRNA.

Adenoviridae↗
PubMed1977

Dental caries and restorations in teenagers. I. Index and score system for radiographic studies of proximal surfaces.

An index and a score system for radiographical longitudinal studies of caries progression on proximal tooth surfaces are presented and compared with the DF-surface system. Generally, a good correlation between DF-surface differences and scores was found in a three-year study on teenagers. However, the score system seems to forward better means for a detailed study of the individual.

Adolescent↗
PubMed1977

Dental caries and restorations in teenargers. II. A longitudinal radiographic study of the caries increment of proximal surfaces among urban teenagers in Sweden.

Within a group of 16 year old school children leaving the regular school dental care, the number of carious lesions and fillings in proximal tooth surfaces was radiographically studied, using an index system. Three years later, the same individuals were re-examined. The results showed that intact surfaces and surfaces with small carious lesions were more resistant to change than others. A minority of the individuals was found to be responsible for a majority of the lesions established during the three year interval. Generally, the progress of caries was slow.

Adolescent↗