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Biomedical subjects

S M Brown

Publications and source records attributed to S M Brown.

At least 145 records · Page 8Linked to original sources
PubMed1989

A variant of herpes simplex virus type 2 strain HG52 with a 1.5 kb deletion in RL between 0 to 0.02 and 0.81 to 0.83 map units is non-neurovirulent for mice.

The virulence of a deletion variant of herpes simplex virus type 2 (HSV-2) strain HG52 has been determined by intracranial inoculation of 3-week-old BALB/c mice. The variant JH2604 has a 1.5 kb deletion within each copy of the long repeat region (RL) of the genome between 0 to 0.02 and 0.81 to 0.83 map units. JH2604 is avirulent for mice compared to the parental wild-type virus, and fails to replicate in mouse brain in vivo. Correction of the deletion by marker rescue resulted in the isolation of recombinants which gave LD50 values comparable to those of individual plaque stocks of the parental HG52. Introduction of the deletion into wild-type virus resulted in recombinants which on intracranial inoculation of mice were avirulent. The results imply that sequences within the 3 kb terminal portion of RL are required for virulence of HSV-2 strain HG52.

Animals↗
PubMed1989

A herpes simplex virus type 2 variant in which a deletion across the L-S junction is replaced by single or multiple reiterations of extraneous DNA.

We have isolated and characterized a novel variant of herpes simplex virus type 2 (HSV-2) strain HG52 which has a deletion of 13.5 kb across the L-S junction of the genome, resulting in all of the IRL region, half of the IRS region and the intervening L-S junction 'a' sequence(s) being removed. The deleted DNA has been replaced by single or multiple (up to 14) reiterations of a DNA sequence approximately 1 kb in length. Individual genomes within the population range in size from approximately 12 kb smaller than unit length to unit length or marginally larger. The L component of the genome is fixed in the prototype orientation while the S component inverts inefficiently. The variant is viable in tissue culture, is not temperature-sensitive, demonstrates impaired single-cycle growth characteristics and, apart from altered mobility of a single species (29.5K), its polypeptide profile in infected cells appears normal. Southern blot analysis has failed to identify the inserted sequences as being derived from HSV-2.

Chromosome Deletion↗
PubMed1989

Drug protocols.

Explore the source record for details and available documents.

Cefotaxime↗
PubMed1989

Therapeutic potpourri.

Many older treatments should not be discarded because of newer modalities. Various dermatologic disorders may be controlled effectively by prescribing these older topical agents.

Complementary Therapies↗
PubMed1988

Neurovirulence of individual plaque stocks of Herpes simplex virus type 2 strain HG 52.

The virulence of ten independent plaque stocks of HSV-2 strain HG 52 was determined by intracranial inoculation of 3 week old BALB/c mice. The ten stocks exhibited a range of LD50 which could be grouped into three classes; high (less than 10(3) pfu/mouse), intermediate (10(3)-10(4) pfu/mouse) and low (greater than 10(5) pfu/mouse). Analysis of the ten stocks using six different restriction endonucleases showed no significant variation in the size and distribution of fragments. Isolates from the brains of dead mice had restriction enzyme profiles indistinguishable from the initial infecting virus. The pfu:particle ratios of the virus stocks were comparable. There were no significant differences between the single growth cycle characteristics in vitro of the parental HG 52 and the various plaque purified stocks. In vivo after intracranial inoculation the low virulence stocks grew poorly while those of high virulence grew well. Plaques were picked from the high and low virulence stocks after passage five times in vitro and re-assayed for virulence. In some cases there were differences in the LD50s of passaged plaque isolates from that of parental stock. The restriction enzyme profiles of the passaged plaque isolates remained unchanged. The analysis has clearly demonstrated virulence heterogeneity within a single HSV-2 virus stock.

Animals↗
PubMed1988

Aetiology of acute pharyngitis and clinical response to empirical therapy with erythromycin versus amoxicillin.

One hundred and eighty-nine adults with acute pharyngitis had culture and serological evaluation for group A beta haemolytic streptococci (GABHS), Mycoplasma pneumoniae, and Branhamella catarrhalis. Sixteen patients had evidence for infection with GABHS, none for M. pneumoniae, and one for B. catarrhalis. For those with GABHS, there was no significant difference between empirical treatment by erythromycin or amoxicillin. For those without GABHS, empirical treatment with erythromycin appeared to result in a statistically significant reduction in cough and a noticeable but less than significant reduction of other symptoms when compared to empirical treatment with amoxicillin. The new formulation of erythromycin utilized in this study (PCE) may be associated with a reduction in gastrointestinal intolerance from that reported with other erythromycin products.

Amoxicillin↗
PubMed1988

Generation of a herpes simplex virus type 2 variant devoid of XbaI sites: removal of the 0.91 map coordinate site results in impaired synthesis of glycoprotein G-2.

Herpes simplex virus (HSV) type 2 (strain HG52) has four XbaI sites at map coordinates (m.c.) 0.45, 0.7, 0.91 and 0.94, i.e. two in the unique long and two in the unique short regions of the genome. Previously, we had isolated a genome containing only the 0.45 and 0.94 XbaI sites. Here we report the isolation of a mutant (JH2611) in which all four XbaI sites have been removed using an enrichment selection procedure, without any loss of viability. Removal of each site has been shown to be due to a base change or small undetectable deletion/insertion of less than 100 bp. In HSV-1, the XbaI site at 0.45 m.c. is in an open reading frame coding for a polypeptide of 14K. Both the 0.7 and 0.94 m.c. HSV-2 XbaI sites are in intergenic positions. The 0.91 m.c. XbaI site has been shown to be within the coding sequence of the glycoprotein gG-2. Synthesis of gG-2 by JH2611 and two other mutants, JH2610 (formerly HG52X163X3) and JH2609 (formerly HG52X163X21), in which the 0.91 m.c. site has been deleted was analysed by immunoprecipitation using the gG-2-specific monoclonal antibodies AP1 and LP5 and the anti-peptide serum 14713. In the mutants JH2610 and JH2611 neither gG-2 nor its precursor were detected but the monoclonal antibodies detected two polypeptides migrating above the normal positions of gG-2 and the gG-2 precursor; these were not precipitated by the anti-peptide serum. With the mutant JH2609 neither gG-2 nor its precursors could be detected by either the monoclonal antibodies or the anti-peptide serum. The results strongly suggest that gG-2 is non-essential for the growth of HSV-2 in vitro.

Chromosome Deletion↗
PubMed1987

Growth and characterization of rabbit corneal cells in vitro.

Primary organ cultures of rabbit corneal epithelium, stroma, and endothelium were established by microdissection. Secondary cultures of epithelial cells, keratocytes, and endothelial cells were established by serial passage. The doubling time for epithelial cells and keratocytes was 18 h, and endothelial cells doubled their number in 5 days. Ultrastructural studies demonstrated characteristic morphological, nuclear, and cytoplasmic features of corneal epithelial cells, keratocytes, and endothelial cells and confirmed the identity of the cell lines. The purity of the three distinct cell types was ascertained by indirect immunofluorescence techniques, using antibodies against keratin, which identified epithelial cells, and fibronectin, which identified keratocytes and endothelial cells. The indirect immunofluorescence technique represents a simple method to screen an aliquot of a cell suspension and determine the purity of corneal cells grown in vitro.

Animals↗
PubMed1987

Three mutants of herpes simplex virus type 2: one lacking the genes US10, US11 and US12 and two in which Rs has been extended by 6 kb to 0.91 map units with loss of Us sequences between 0.94 and the Us/TRs junction.

In the process of generating restriction endonuclease site deletion mutants, we have isolated and characterized three mutants of herpes simplex virus type 2 (HSV-2), strain HG52, with large genomic deletions in Us and TRs. The deleted sequences (7.5 kb) extend from 0.94 map coordinates (m.c.) to 0.99 m.c. and are presumed to contain the HSV-2 gene equivalents of US10, 11 and 12, one copy of immediate early (IE) gene 3 and one copy of an origin of replication (ORIs). One of the mutants (HG52X163X12) has a simple deletion whereas in the two others (HG52X163X14 and HG52X163X21) the deleted sequences have been replaced by inverted duplications of Us/IRs sequences between 0.83 and 0.91 m.c. such that the molecules have short region inverted repeats extended by 6 kb on either side. All three are viable, stable and grow in tissue culture indicating that the polypeptides coded by the HSV-2 genes equivalent to US10, 11 and 12 are non-essential for lytic growth in BHK21/C13 cells. In addition the lack of one copy of the HSV-2 equivalent of IE gene 3 and ORIs in HG52X163X12 shows that only one copy of each suffices for viability. However the temperature restriction of the mutants at 38.5 degrees C suggests that one or more of the polypeptides coded by the deleted sequences may be required in conjunction with another polypeptide(s) for viral growth or stability at the higher temperature.

Animals↗
PubMed1987

Deletion and duplication variants around the long repeats of herpes simplex virus type 1 strain 17.

Three variants of herpes simplex virus type 1 strain 17 were isolated. One variant had a deletion of 2.5 X 10(6) Mr in IRL/UL and 0.8 X 10(6) Mr in TRL such that sequences were deleted from both long repeats. The deletion in UL removed the 20K and 22K open reading frames. The second variant had a deletion of 3.5 X 10(6) Mr in IRL/UL which again removed the 20K and 22K open reading frames. The third variant had a similar deletion in UL, but in this case the deleted sequences were replaced by sequences from the left end of UL, such that the long repeat was extended by 3 X 10(6) Mr and the overall genome size by 2 X 10(6) Mr. All three variants grew almost normally in vitro. The analysis of 11 isolates with extensive variation in the long repeats outside the 'a' sequence is also reported.

Biological Evolution↗
PubMed1987

Herpes simplex virus type 1 latency in rabbit corneal cells in vitro: reactivation and recombination following intratypic superinfection of long term cultures.

Herpes simplex virus type 1 (HSV-1) has been isolated from explanted human corneas after cultivation in vitro. To determine whether HSV-1 is persistent or latent in corneal cells, a system to study HSV-1 infection of rabbit corneal cells in vitro was developed. By elevation of the incubation temperature to 42 degrees C before and during HSV-1 infection it was shown that both keratocytes and epithelial cells support a nonproductive rather than a productive infection. On subsequent temperature reduction to 37 degrees C, infectious virus was released from both cell types. Addition of the viral inhibitor acycloguanosine during the last 5 days of a 14 day incubation at 42 degrees C did not reduce the frequency of viral shedding following transfer to 37 degrees C, indicating that corneal cells support a latent as opposed to persistent infection. Cultures which failed to shed virus spontaneously up to 29 days post-inoculation were superinfected at 37 degrees C, with an XbaI site deletion mutant of HSV-1. Restriction endonuclease analysis of progeny identified both the initial infecting virus and recombinants between the parental and superinfecting genomes.

Animals↗
PubMed1987

Generation of a herpes simplex virus type 1 variant devoid of XbaI sites.

Using both selection enrichment and site-directed mutagenesis, a herpes simplex virus type 1 (HSV-1) strain 17 genome lacking all four XbaI sites has been generated. The site at 0.45 map units which lies within the gene coding for a polypeptide of 28,000 molecular weight was removed by selection enrichment, while the site at 0.29 map units which lies within the gene coding for glycoprotein H was removed by site-directed mutagenesis. The parental virus from which these two XbaI sites were deleted had previously had the sites at 0.07 and 0.63 map units removed through selection enrichment. The variant devoid of XbaI sites (X4) showed normal growth characteristics; its phenotype was normal apart from the absence of the thymidine kinase protein, which is believed to be unrelated to the loss of XbaI sites.

Chromosome Deletion↗
PubMed1987

A herpes simplex virus type 1 variant which fails to synthesize immediate early polypeptide VmwIE63.

We report the isolation of a variant (X2D) of herpes simplex virus type 1 strain 17 which has a deletion of 5 X 10(6) mol. wt. in the long unique and long inverted repeat regions, such that one copy of the immediate early (IE) gene 1 and two unique open reading frames coding for polypeptides of 20K and 22K are deleted. The mutant X2D synthesizes reduced levels of VmwIE110, and also apparently fails to synthesize VmwIE63, at both the protein and RNA levels, despite there being no apparent deletion in the coding or controlling regions of the IE2 gene. X2D also fails to synthesize the thymidine kinase polypeptide but exhibits normal growth characteristics in tissue culture.

Chromosome Deletion↗
PubMed1987

Recovery of herpes simplex virus from the corneas of experimentally infected rabbits.

Rabbits were inoculated in the left cornea with one of three strains of herpes simplex virus (HSV) i.e. HSV-1 strain 17, HSV-1 strain McKrae, HSV-2 strain HG52, or with and HSV-1 McKrae/HSV-2 HG52 recombinant R40/2. Fifty-nine to 67 days after inoculation trigeminal ganglia and corneas were explanted and screened for release of infectious virus. Virus was isolated from all left trigeminal ganglia after organ culture irrespective of viral strain. Virus was isolated from three of 16 corneas of animals inoculated with HSV-1 strain McKrae and from one of four corneas from animals inoculated with the HSV-1/HSV-2 recombinant. The isolation of HSV from explanted corneas, after between 15 and 35 days in organ culture suggests that the cornea may be a site additional to dorsal root ganglia where latent HSV can reside in rabbits.

Animals↗
PubMed1987

Early congenital syphilis and severe haematological disturbance.

The early clinical signs and symptoms of congenital syphilis are diverse but, if undiagnosed, signs of the disease may subside until the late stigmata appear. We report a case that illustrates that the haematological signs and symptoms may be so severe as to mimic a diagnosis of leukaemia or disseminated malignant disease.

Diagnosis, Differential↗
PubMed1986

Chemical spill exposure assessment.

POSSM, the PCB On-Site Spill Model, is a contaminant transport model developed to predict environmental concentrations associated with a chemical spill. The model predicts daily changes in chemical concentrations on a spill site (e.g., in soil and on vegetation) and losses of chemical due to volatilization, surface runoff/soil erosion, and leaching to groundwater. Spill areas consisting of soil/vegetation and/or an impervious surface (e.g., asphalt and concrete) can be analyzed, as can different spill cleanup practices. POSSM is used to analyze exposure levels associated with a hypothetical capacitor spill. While the model was developed for PCB spills, it is generally applicable to a number of organic compounds.

Accidents↗
PubMed1986

Herpes simplex virus type 1 persistence and latency in cultured rabbit corneal epithelial cells, keratocytes, and endothelial cells.

Cell cultures of rabbit corneal epithelium, keratocytes, and endothelium were used to determine the lytic cycle of herpes simplex virus type 1. Viral growth was fastest in epithelial cells. A novel HSV-1 in-vitro latency system was established in the three distinct cell types. Cell cultures were inoculated at low multiplicities of infection with HSV-1. Temperature manipulation alone was used to induce and reactivate latent HSV-1 infections. The presence of cellular stress proteins was demonstrated at supraoptimal temperatures. All cell types were capable of maintaining latent viral infections under these conditions. Viral persistence was present in 20% of epithelial cell cultures at supraoptimal temperatures, but not in keratocyte cultures or endothelial cell cultures.

Animals↗