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Biomedical subjects

F Brown

Publications and source records attributed to F Brown.

At least 181 records · Page 10Linked to original sources
PubMed1984

Relationship of encephalomyocarditis virus to cricket paralysis virus of insects.

Cricket paralysis virus was shown to share common antigen(s) with encephalomyocarditis virus (Cardiovirus: Picornaviridae), a virus normally associated with mammals. These viruses must be regarded now as being related strains of one and the same virus. These results pose interesting questions for the taxonomy and ecology of small RNA viruses.

Animals↗
PubMed1984

Genetically engineered vaccines: problems and promises.

Determinants of important protective antigens from a variety of viral, bacterial and parasite pathogens have been successfully cloned and expressed in novel hosts using recombinant DNA techniques. The use of these cloned determinants in the development of new vaccines, including immunologically defined subunit vaccines, genetically defined live attenuated vaccines, and synthetic peptide vaccines is described.

Animals↗
PubMed1983

Synthetic peptides mimic subtype specificity of foot-and-mouth disease virus.

The major immunogen of foot-and-mouth disease virus (FMDV) is located between amino acids 141-160 of the capsid protein VP1. Synthetic peptides corresponding to the major immunogenic region give good neutralising antibody responses and protection in guinea pigs. To define more precisely the immunogenic site of the virus, we have examined serological differences between subtypes of the A serotype using synthetic peptides covering the 141-160 region. We show that these synthetic peptides carry determinants which mimic the subtype specificity of the virus. The correlation between these results and predictive structural models, based on the amino acid sequence, is discussed.

Amino Acid Sequence↗
PubMed1983

Isolation and characterization of a trypsin-like serine proteinase from the membranes of Walker 256 carcino-sarcoma cells.

A serine proteinase was isolated from Walker-256-carcino-sarcoma plasma-membrane-enriched preparations by affinity chromatography employing soya-bean trypsin inhibitor as the ligand. This enzyme was termed 'memsin' owing to its membrane location and trypsin-like substrate specificity. Analysis of this preparation by steric-exclusion high-pressure liquid chromatography (h.p.l.c.) resulted in a single peak of enzyme activity. Calculations of the rates of inactivation of memsin by peptidyl-chloromethanes and comparison with rate constants obtained with other serine proteinases indicated that memsin closely resembled trypsin and acrosin. Digestion of oxidized ribonuclease by memsin and analysis of the resulting peptides by h.p.l.c. yielded a chromatogram that was very similar to one generated by a tryptic digest of oxidized ribonuclease. This enzyme could possibly play a role in tumour-cell invasion.

Animals↗
PubMed1983

Effect of vesicular stomatitis virus and Semliki Forest Virus on uptake of nutrients and intracellular cation concentration.

BHK-21 cells showed an increased ability to concentrate 2-deoxy-D-glucose (dGlc) 2 to 3 h after infection with vesicular stomatitis virus (VSV) or Semliki Forest virus (SFV), which began to be released at 2 and 3 h post-infection respectively; uptake of other nutrients was not affected in this way. Intracellular Na+ was either unchanged (VSV-infected cells) or increased (SFV-infected cells); K+ content was unchanged. These results do not support the current hypothesis that a non-specific increase in membrane permeability occurs in cells infected with rhabdoviruses or togaviruses.

Animals↗
PubMed1983

Characteristics of an adenylate cyclase coupled beta 2-adrenergic receptor in a smooth muscle tumor cell line.

We have shown that binding of 3H-dihydroalprenolol ( [3H] DHA) to DDT1 MF-2 cells and cell membranes was of high affinity, saturable, stereoselective and reversible. The [3H]DHA dissociation constants were 0.63 +/- 0.15 nM (n = 6) and 0.83 +/- 0.04 nM (n = 5) for intact cells and cell membranes, respectively, with a binding site concentration for cells of 27,300 +/- 5,200 sites/cell (n = 6) and for membranes 468 +/- 24 fmoles/mg protein (n = 5). The order of agonist competition for the [3H]-DHA binding site of DDT1 cell membranes was isoproterenol (Ki = 0.20 +/- 0.07 microM) greater than epinephrine (Ki = 0.4 +/- 0.2 microM) greater than norepinephrine (Ki = 66.5 +/- 5.15 microM) consistent with a beta 2-adrenergic receptor interaction. Zinterol, a beta 2-selective antagonist, (Ki = 0.05 +/- 0.01 microM) was 18X more effective than metoprolol, a beta 1-selective antagonist (Ki = 0.9 +/- 0.1 microM), in competing for the DHA binding site. A nonlinear iterative curve fitting analysis of zinterol and metoprolol binding isotherms indicated that (p greater than 0.05) DDT1 cells possess a pure population of beta 2-adrenergic receptors. Finally, we have shown that DDT1 MF-2 cell beta 2-adrenergic receptor is functionally coupled to adenylate cyclase via a G/F protein complex as demonstrated in part by a guanine nucleotide requirement for isoproterenol stimulation of adenylate cyclase activity. In addition, guanine nucleotide mediated a reduction in the affinities of isoproterenol and epinephrine for the [3H]DHA binding site.

Adenylyl Cyclases↗
PubMed1982

Characterization of Theiler's murine encephalomyelitis virus RNA.

Theiler's murine encephalomyelitis viruses are usually included in the enterovirus genus of the family Picornaviridae, although there is little physicochemical evidence to support this classification. In this report, the size of the RNA of highly virulent and less virulent representatives of the Theiler's group of viruses has been determined by sucrose gradient centrifugation and electrophoresis in agarose to be the same as that of other enteroviruses. The absence of a poly(C) residue provides evidence that these viruses are not cardioviruses or aphthoviruses. The base composition of the two members are similar to each other but differ from those of other enteroviruses. However the one- and two-dimensional maps of the ribonuclease T1 hydrolysates of the two virus RNAs show considerable differences despite their close serological similarity. Virus-specified RNA synthesis in cells infected with the more virulent strain of the virus was almost 10 times greater than that induced by the less virulent strain, in accord with the yields of virus particles.

Base Composition↗
PubMed1982

Nature of the antibody response to the foot-and-mouth disease virus particle, its 12S protein subunit and the isolated immunizing polypeptide VP1.

Inoculation of inactivated 146S foot-and-mouth disease virus particles into guinea-pigs elicited the formation of neutralizing antibody and the serum had a 10-fold higher titre in radioimmunoassay (RIA) with 146S particles than with the 12S virus subunit. In contrast, a single inoculation of the 12S subunit or the isolated polypeptide VP1 elicited the formation of antibody having a much lower titre in RIA with the 146S particle than with the 12S subunit and low or undetectable neutralizing activity. However, sera from guinea-pigs given two or more inoculations of the 12S subunit or VP1 had neutralizing activity. The level in the anti-VP1 serum was lower than that in the anti-12S serum and both were much lower than that in animals receiving two inoculations of the 146S particle. The neutralizing activity elicited by the three antigens was absorbed by the homologous antigen. In contrast, neither the 12S subunit nor VP1 absorbed the anti-146S neutralizing antibody and VP1 did not absorb the anti-12S subunit neutralizing antibody. However, the 12S subunit partly absorbed the neutralizing activity elicited by VP1. The results are compatible with a model in which the 146S particle elicits a spectrum of neutralizing antibodies which are completely absorbed by the homologous particle but only partially by the 12S subunit or VP1. The results are discussed in relation to the structural features required for the production of neutralizing antibody.

Animals↗
PubMed1982

Application of RNase T1 one- and two-dimensional analyses to the rapid identification of foot-and-mouth disease viruses.

The analysis of several isolates of foot-and-mouth disease virus by RNase T1 fingerprinting of the 32P-labeled RNA is described. It has been shown that use of the 35S induced RNA instead of the virus particle RNA has two advantages. (i) About 40 times more radioactivity is incorporated into the induced RNA. (ii) The RNA can be prepared much more rapidly, thus increasing the value of the technique in rapid diagnosis. One-dimensional maps, in which the RNase T1 oligonucleotides are separated according to size, have been shown to provide a valuable screening method for distinguishing between viruses. Those viruses giving similar one-dimensional maps also gave similar two-dimensional maps. The value of using the length of the polycytidylic acid tract of foot-and-mouth disease virus as a diagnostic tool is also discussed.

Aphthovirus↗
PubMed1981

Molecular cloning of foot and mouth disease virus genome and nucleotide sequences in the structural protein genes.

Foot and mouth disease virus (FMDV), of the family Picornaviridae, consists of a single-stranded RNA (approximately 8,000 nucleotides), the translation of which is initiated on the 3' side of a 150-nucleotide poly(C) tract and yields a single polyprotein which is processed by host cell proteases into four primary products (Fig. 1). One or more virus-specified proteases further cleave these into the final products, the capsid proteins (VP1-4) being derived from the precursor p88 (for review see ref. 5). There are seven serotypes of the virus and as it has been shown that the immunizing activity of FMDV particles is associated primarily with VP1 (refs 6, 7), it seems likely that antigenic variation in FMDV is a result of changes in the structure of this protein. To further our understanding of this variation and as a first step in the possible development of FMDV vaccines from genetically manipulated microorganisms, we report here the construction and analysis of recombinant plasmids containing cDNA copies of the RNA. Comparison of the deduced amino acid sequence with the known polypeptide sequences shows that the NH2-termini of VP2 and VP3 are conserved between the A and O serotypes whereas that of VP1 (the immunizing antigen) varies by as much as 42% between serotypes.

Amino Acid Sequence↗