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F Brown

Publications and source records attributed to F Brown.

At least 19 recordsLinked to original sources
PubMed1996

Evaluation of HER-2 neu oncoprotein expression as a prognostic indicator of local recurrence in conservatively treated breast cancer: a case-control study.

PURPOSE: The purpose of this study is to determine the prognostic significance of overexpression of the HER-2 neu oncoprotein with respect to local relapse following conservative surgery and radiation therapy (CS + RT). METHODS AND MATERIALS: Twenty consecutive patients who sustained a local recurrence as the first and only site of failure following CS + RT comprised the case population base for this study. Only patients who received no adjuvant systemic chemotherapy or tamoxifen were selected for analysis. Following the identification of 20 consecutive local-relapse patients, the patient database was searched for 20 matching control patients who did not sustain a local relapse. Each control patient was matched to the index case with respect to age, menopausal status, follow-up, primary histology, axillary nodal status, and primary tumor size. Both index cases and the matched control group received full course radiation therapy, to a total dose of 64 Gy to the tumor bed. The paraffin-embedded blocks of the original primary tumor of the local-relapse cases and the primary tumor of 20 matched controls were processed for immunohistochemical staining of the HER-2 neu oncoprotein. Each slide was rated on the 3-point scale, 0 representing no stain, 1+ indicating light staining, and 2+ denoted heavy staining (overexpression). RESULTS: Of the 20 index cases, with each of the matched controls, 16 were evaluable for analysis. The 4 cases that were eliminated had inadequate paraffin-embedded material in either the case or the match control for adequate staining. By design of the study, the index case group and control group had similar ages (52 years index vs. 51.4 control), follow-up (10.8 years index vs. 10.5 years control), and histologies. For the immunostaining, a value of 2+ was considered to denote high activity and overexpression, and 0 and 1+ were considered negative values. Using these criteria, a total of 9 of the 16 index cases (56%) exhibited overexpression of HER-2 neu oncoprotein, and only 3 of the 16 control cases (18%) demonstrated high immunoreactivity. The difference in immunostaining between the index and control cases was statistically significant by a Pierson chi-square analysis at the p = 0.03 level. CONCLUSIONS: In this matched case-control study, overexpression of the HER-2 neu oncoprotein appears to have prognostic significance with respect to local relapse in the conservatively treated breast. The correlation of overexpression of HER-2 neu by multivariable analysis with other prognostic factors for local recurrence warrants further investigation. The clinical implications of the study are discussed.

Adult↗
PubMed1996

Absence of protein 2C from clarified foot-and-mouth disease virus vaccines provides the basis for distinguishing convalescent from vaccinated animals.

We have recently reported that cattle and pigs which have been vaccinated against foot-and-mouth disease can be distinguished from convalescent animals by the absence of antibodies to viral non-structural protein 2C (Lubroth and Brown, Res. Vet. Sci., 1995, 59, 70-78(1)). In this study, we show that the absence of 2C antibodies from the sera of vaccinated animals can be explained by the association of this viral protein with cellular debris which is separated from the virus harvest prior to inactivation of the supernatant for vaccine production. This serological marker can be of great value in countries where the disease occurs or in the veterinary regulatory arena when livestock are transported across borders, since it can be used to identify convalescent, persistently infected animals and vaccinates exposed to wild-type virus variants which have infected the vaccinated animals.

Animals↗
PubMed1996

Chimeric hepatitis B virus core particles as probes for studying peptide-integrin interactions.

An RGD-containing epitope from the foot-and-mouth disease virus (FMDV) VP1 protein was inserted into the e1 loop of the hepatitis B virus core (HBc) protein. This chimeric protein was expressed at high levels in Escherichia coli and spontaneously assembled into virus-like particles which could be readily purified. These fusion particles elicited high levels of both enzyme-linked immunosorbent assay- and FMDV-neutralizing antibodies in guinea pigs. The chimeric particles bound specifically to cultured eukaryotic cells. Mutant particles carrying the tripeptide sequence RGE in place of RGD and the use of a competitive peptide, GRGDS, confirmed the critical involvement of the RGD sequence in this binding. The chimeric particles also bound to purified integrins, and inhibition by chain-specific anti-integrin monoclonal antibodies implicated alpha 5 beta 1 as a candidate cell receptor for both the chimeric particle and FMDV. Some serotypes of FMDV bound to beta 1 integrins in solid- phase assays, and the chimeric particles competed with FMDV for binding to susceptible eukaryotic cells. Thus, HBc particles may provide a simple, general system for exploring the interactions of specific peptide sequences with cellular receptors.

Animals↗
PubMed1996

Constitutive activation of a single effector pathway: evidence for multiple activation states of a G protein-coupled receptor.

A cysteine-to-phenylalanine mutation in the third transmembrane domain of the alpha 1B-adrenergic receptor constitutively activates the receptor, resulting in G protein coupling in the absence of agonist and activation of only a single effector pathway (phospholipase C but not phospholipase A2). This mutant receptor displays a higher affinity for the catecholamines, norepinephrine, and epinephrine, as well as for other phenethylamines, but not for imidazolines, a class of structurally distinct alpha agonists. Dose-response studies demonstrate a higher potency and intrinsic activity of phenethylamines for polyphosphoinositide turnover but not for arachidonic acid release. Imidazolines have wild-type potencies and intrinsic activities for both pathways. These data indicate that a single receptor subtype forms multiple conformations (i.e., exhibits induced conformational pleiotropy) for G protein interactions (high affinity states) that are specific for a particular G protein/effector pathway and that multiple binding sites exist for agonists, which promote or induce these specific interactions. Pharmacological diversity may, thus, be achieved through a single receptor by the development of compounds that induce a single activated conformer. This has major ramifications for the eventual development of signaling-specific therapeutics.

Adrenergic alpha-Antagonists↗
PubMed1995

Scanning tunnelling microscopy studies of beta-amyloid fibril structure and assembly.

Alzheimer's disease is in part characterised by the deposit of beta-amyloid peptide in the form of fibrils in the brain. In this study, the scanning tunnelling microscope (STM) has been used to provide high resolution images of synthetic fibril structure and formation as a function of time. Short fibrils are observed following brief peptide incubation times. At longer incubation periods ribbon like filaments were observed. These results suggest that beta-amyloid self-assembly is an ordered process, with a correlation between time of incubation and length of beta-amyloid filament growth.

Amino Acid Sequence↗
PubMed1995

Characterization of an acid-resistant mutant of foot-and-mouth disease virus.

A foot-and-mouth disease virus mutant which is stable at pH 6.4 has been isolated from a virus of serotype A. In contrast to the parent (P) virus, which gave a mixture of large and small plaques in BHK21 cells and in a bovine kidney cell line, the acid-resistant (AR) virus gave small plaques which did not increase markedly in size after 24 hr. The infectivity titer of the acid-resistant virus was about 100-fold lower in suckling mice than in BHK21 cells, whether the inoculation was made intraperitoneally or intracerebrally, whereas the parent virus gave similar titers in both systems. Furthermore, in mice the AR virus reached its end point two to three times more slowly. The diameter of the AR virus was almost 20% less than that of the P virus and it had a more distinct topography, but the two viruses cosedimented in sucrose gradients. However, the buoyant density in CsCl of the AR virus was slightly lower (1.42 compared with 1.43 g/cc) in coruns. The RNAs and capsid proteins of the two viruses gave similar profiles in sucrose gradients and by SDS-PAGE, respectively. However, isoelectric focusing of the capsid proteins revealed considerable differences between the two viruses. Whereas the P virus gave four protein bands, corresponding to VP1-VP4, the AR virus gave one band for VP4, two for VP3, two for VP2, and four for VP1. Sequence analysis of the genes coding for the capsid protein regions of the two viruses showed four changes (one silent), resulting in an Ala-3-->Ser substitution in VP1 and Glu-131-->Lys and Asp-133-->Ser substitutions in VP2.

Animals↗
PubMed1995

Aggregation state and neurotoxic properties of Alzheimer beta-amyloid peptide.

The behaviour of synthetic batches of beta-amyloid (beta A) 1-40 peptide in solution has been studied. The effects of beta A1-40 on a PC12 cell toxicity assay was dependent upon the time of preincubation of an aqueous solution of the peptide before application to the cells. Fibrillization of the beta A1-40, quantitatively assessed by the binding of Congo red to amyloid fibrils, also increased in a time dependent manner over the 168 h incubation period studied. The degree of Congo red binding, in the absence of any preincubation, differed between two synthetically distinct batches of the peptide. The rate of development of fibril formation during subsequent incubation also differed between the two batches and appeared to parallel the effects on cell viability. Infra-red spectroscopic analysis revealed beta-sheet formation for both batches and other more subtle conformational differences between the peptides. Electron microscope examination of the batches of beta A1-40 confirmed the difference in occurrence and development of fibrils. At high magnification, fibrils of both batches exhibited a helical structure. The results suggest that the development of neurotoxicity of beta A1-40 is related to the fibrillar state of the peptide.

Alzheimer Disease↗
PubMed1995

Identification of native foot-and-mouth disease virus non-structural protein 2C as a serological indicator to differentiate infected from vaccinated livestock.

Cattle and pigs which have been vaccinated against foot-and-mouth disease can be distinguished from convalescent animals by radio-immunoprecipitation and sodium dodecyl sulphate polyacrylamide gel electrophoresis of the virus-induced proteins reacting with the respective sera. Baby hamster kidney cells infected with foot-and-mouth disease virus (FMDV) (serotype A24) were labelled with 35S-methionine and the virus-induced proteins were precipitated with sera from vaccinated and subsequently challenged animals, convalescent animals retained for over 300 days, animals vaccinated or infected with viruses belonging to all serotypes of FMDV, and animals infected with encephalomyocarditis (EMC) or porcine or bovine enteroviruses. In addition to the structural proteins of the virus, the non-structural proteins 2C, 3ABC, 3C, 3CD and 3D were precipitated by convalescent sera, but only 3D was precipitated by serum from vaccinated animals. Proteins L, 2C and 3C were precipitated only after challenge with a heterotypic virus (serotype O1 Tunisia), indicating that virus replication of the challenge virus had taken place. No precipitation was detected with sera from EMC or enterovirus-infected animals. The results indicate that protein 2C, and to a lesser extent the polypeptide 3ABC, could be used to differentiate potential carrier convalescent animals from vaccinated livestock.

Animals↗
PubMed1995

Antigenic variants in a plaque-isolate of foot-and-mouth disease virus: implications for vaccine production.

The occurrence of many subtypes within a serotype of foot-and-mouth disease virus (FMDV) makes it difficult to control the disease by vaccination. Although inactivated vaccines are used successfully in many countries, the appearance in the field of antigenic variants against which the vaccines do not confer protection is a constant problem in vaccine manufacture. We had found previously a mixture of antigenic variants in a field isolate of serotype A12. In this report we demonstrate the presence of two variants in a plaque-isolate from this mixture. The second variant was detected only when the growth conditions were altered. Our observation points to the problems which may be encountered in the large scale growth of a virus for vaccine production.

Amino Acid Sequence↗
PubMed1995

Stabilising oral poliovaccine at high ambient temperatures.

The oral poliovaccine strains lose infectivity when they are stored above refrigerator temperatures. These losses increase rapidly at the high temperatures encountered in tropical countries, thus causing problems if the cold chain is inadequate. Attempts to minimise these losses have generally relied on the addition of salts such as MgCl2. In this paper we show that the fall in infectivity, which is due to the hydrolysis of the genomic RNA by the RNA polymerase within the virus particle, can be greatly inhibited by the suppression of this enzymatic activity. This can be achieved simply by reducing the pH below 7.

DNA-Directed RNA Polymerases↗
PubMed1995

Structure and immunogenicity of experimental foot-and-mouth disease and poliomyelitis vaccines.

The physico-chemical properties and immunogenicity of experimental vaccines against foot-and-mouth disease (FMD) and poliomyelitis, prepared by treatment of the viruses with N-acetylethyleneimine (AEI), formaldehyde or neutral red, have been studied. None of these reagents affects the rate of sedimentation of the particles or their reaction with antibody against the major immunogenic sites. FMD vaccines prepared by inactivation with AEI or neutral red, behaved like the untreated virus, in that they were disrupted on lowering the pH below 7. The RNA of the AEI-inactivated virus was degraded into slowly sedimenting molecules. Unlike AEI-inactivated virus, from which all the RNA could be extracted with phenol-SDS, the recovery from the neutral red inactivated virus was variable and was sometimes as low as 40%; this RNA gave a heterogenous profile in sucrose gradients. The capsid proteins in the AEI preparation migrated in SDS-PAGE to the same positions as those of untreated virus, but in the neutral red preparation there was evidence of cross-linking. In contrast, the formaldehyde-inactivated vaccine was stable below pH 7 and the RNA could not be released by extraction with phenol-SDS at pH 5, because the capsid proteins had become cross-linked and/or linked to the RNA. As with foot-and-mouth disease virus (FMDV), poliovirus which had been inactivated with formaldehyde did not release its RNA on extraction with phenol-SDS and the capsid proteins were also cross-linked. Surprisingly, although AEI cleaved the viral RNA slowly in situ, the virus was no longer infectious after 6 h. Neutral red did not reduce the infectivity of the virus. All of the preparations gave similar levels of neutralizing antibody after a single inoculation. The high levels obtained with the formaldehyde-inactivated vaccines have implications for the processing of fixed particles by the antigen-presenting cells.

Animals↗
PubMed1995

Differences in qualitative brain morphology findings in schizophrenia, major depression, bipolar disorder, and normal volunteers.

This study examined the frequency and type of qualitative brain morphologic anomaly as a function of sex and diagnosis. Magnetic resonance imaging brain scans were evaluated by an experienced neuroradiologist blind to diagnosis. The scans of 325 individuals (108 schizophrenic, 20 schizoaffective, 27 major depressive, 20 bipolar and 150 healthy volunteers) were categorized into one of five groups: normal, hyperintensity signals, volume loss, ventricular anomaly or "other" abnormality. Schizophrenic men had significantly more morphologic anomalies, especially of the lateral ventricles than healthy male volunteers. Schizophrenic women did not differ from healthy women. Schizoaffective patients of both sexes, male depressive and female bipolar patients were also characterized by higher rates of brain anomalies. Independent of diagnosis, women were more likely than men to have hyperintensity signals among individuals with positive scan findings. The overall rate of brain morphologic anomalies is significantly higher among male schizophrenic patients than healthy volunteers; this is not specific to male schizophrenics, however, suggesting a global sex effect. Type of anomaly may differ by sex and give us clues about sex differences in the pathophysiology of psychopathology.

Adult↗
PubMed1994

Circular dichroism, molecular modeling, and serology indicate that the structural basis of antigenic variation in foot-and-mouth disease virus is alpha-helix formation.

Seven antigenic variants obtained from a single field isolate of foot-and-mouth disease virus, serotype A12, differ only at residues 148 and 153 in the immunodominant loop of viral protein VP1. Synthetic peptides corresponding to the region 141-160 are highly immunogenic. UV circular dichroism shows that (i) in aqueous solution the peptides are nearly identical, but in 100% trifluoroethanol they display helix-forming properties which correlate well with their serological crossreactivities for anti-peptide sera, and (ii) these properties are insensitive to substitutions at position 153, except for proline, but are highly sensitive to substitutions at position 148. This pattern can be explained by the effects of these substitutions on the amphiphilic character and positions of helices postulated in the region 146-156. Molecular models indicate that residues 147, 148, 150, 151, 153-155, and 157 are most likely to interact with residues of the antibody paratopes. The data are consistent with the existence of an inverse gamma-turn around Pro-153, and a beta-turn at the cell-attachment site at residues 145-147.

Amino Acid Sequence↗
PubMed1994

The Leeuwenhoek Lecture, 1993. Peptide vaccines: dream or reality?

Small fragments of micro-organisms which elicit protective immune responses have now been identified for several disease-causing agents. This major advance has made it possible to envisage the chemical synthesis of vaccines which could replace those in current use and may also furnish products which cannot be made by traditional methods. In my lecture I will illustrate the principles involved by describing the advances made with synthetic vaccines for foot-and-mouth disease, hepatitis B and malaria.

Animals↗
PubMed1994

Foot-and-mouth disease virus particles contain replicase protein 3D.

An antibody against the Escherichia coli-expressed RNA polymerase of foot-and-mouth disease virus (FMDV) reacts with the virus in ELISA and radioimmunoprecipitation experiments and with a protein of the disrupted virus particle in an immunoblot analysis. Treatment of the virus with trypsin, which cleaves capsid protein VP1 and a 56-kDa polypeptide present in trace amount in the particles, reduces the level of the reaction in ELISA and radioimmunoprecipitation and eliminates the immunoblot reaction. Electron microscopy showed that only approximately 20% of the virus particles reacted with the anti-polymerase antibody, whereas most reacted with an antibody against the immunodominant G-H loop of the virus. In the presence of ammonium ions, the expressed polymerase degrades the RNA of the virus into molecules sedimenting at approximately 12 S, indicating that it can act as a hydrolytic as well as a polymerizing enzyme. Moreover, the RNA in trypsin-treated virus particles is degraded when incubated at 37 degrees C, suggesting that the cleaved 56-kDa protein still possesses hydrolytic activity. In addition, the anti-polymerase antibody, which inhibits the polymerase activity of the E. coli-expressed protein, also partially inhibits the hydrolytic activity of the previously described endonuclease of the virus particle, suggesting that this enzyme is identical with the polymerase or forms part of it.

Antibodies, Viral↗