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Biomedical subjects

S Patrick

Publications and source records attributed to S Patrick.

At least 37 records · Page 2Linked to original sources
PubMed1995

Immunological detection of Bacteroides fragilis in clinical samples.

A monospecific polyclonal antiserum, prepared against Bacteroides fragilis common polysaccharide antigen purified by polyacrylamide gel immunoblot detected B. fragilis, B. thetaiotaomicron, B. ovatus and Prevotella melaninogenica in pus samples from various anatomical sites by immunofluorescence microscopy of the pus. With standard clinical laboratory culture methods, 36% of 147 samples were positive for one or more of the above bacteria. Of these, B. fragilis accounted for 33%. By immunofluorescent labelling of pus with the common antigen antiserum the detection of these bacteria in the samples increased to 50%. All nine of the blood cultures in which B. fragilis was detected by culture contained bacteria positive for the common antigen. Immunofluorescent labelling of pus samples with a selection of monoclonal antibodies specific for surface polysaccharides which are known to be antigenically variable in culture in vitro and in an animal model of infection showed that these polysaccharides are also variable in natural infection. The results indicate that the common polysaccharide antigen, in contrast to the variable surface polysaccharides, is a suitable target for the immunodetection of B. fragilis in clinical samples from a range of anatomical sites.

Animals↗
PubMed1995

EEG and seizure outcome after epilepsy surgery.

The significance of the EEG after epilepsy surgery is not fully understood. We investigated the association between postoperative EEG abnormalities and persistent seizures after epilepsy surgery as they relate to pathologic lesions. Among 254 patients who underwent epilepsy surgery between 1987 and 1991, we identified 78 patients who had mesiotemporal sclerosis (MTS) and 47 patients who had low-grade brain tumors, all of whom had 6- to 18-month postoperative follow-up including EEG. Patients who had other pathology, multiple operations, callosotomy, or hemispherectomy, or who were aged < 18 years or who had insufficient EEG data, were excluded. Patients were classified as having persistent seizures or being seizure-free since operation. EEG abnormalities were abstracted from EEG reports 6-18 months postoperatively. Seizures persisted in 24% of the MTS group and in 27% of the tumor group. Of those with normal EEGs, none of the MTS patients and only 1 of the tumor patients had persistent seizures (p = 0.03 for MTS and p = 0.42 for tumor). Epileptiform discharges and focal slowing were associated with seizure persistence in both groups, but to a significant extent only in the MTS group. In the MTS group, patients who had both epileptiform discharges and focal slowing were more likely to have persistent seizures than were those with either abnormality alone.

Adult↗
PubMed1992

Search for enteric microbial pathogens in patients with ulcerative colitis.

Microbial pathogens were sought in faeces of patients with active ulcerative colitis and again after 3 months treatment. 64 patients were examined during their first episode of ulcerative colitis and 30 with relapse of chronic disease. At presentation, bacterial pathogens were not found; 1 patient had cryptosporidiosis. In 10 patients treatment appeared to result in some loss of colonisation resistance as evidenced by colonisation with beta-haemolytic streptococci, Staphylococcus aureus, candida and Clostridium difficile. Unidentified cytotoxic activity was present in the faeces of 4 patients at presentation and 2 patients during or after treatment. We conclude that enteric infection is an uncommon finding in patients with active ulcerative colitis.

Colitis, Ulcerative↗
PubMed1991

The mortality of children with type 1 (insulin-dependent) diabetes mellitus in Norway, 1973-1988.

The mortality status of all individuals in Norway with the onset of Type 1 (insulin-dependent) diabetes mellitus from 1973 through 1982 and age at onset below 15 years was determined as of 1 July 1988. Of the 1908 cases included in the follow-up, 20 had died (15 males and 5 females) and 10 had emigrated. A two-fold increased risk for early mortality was exhibited among this cohort. Life-table analyses did not find sex or age at onset of Type 1 diabetes to be statistically significant predictors of survival when controlling for diabetes duration. A review of death certificates revealed that accidents and suicides accounted for 40% of the deaths in the total cohort and that this cause of death occurred only among male subjects. Acute diabetes related complications were the underlying causes of death for 35% of the subjects. Diabetic renal disease and death by cardiovascular disease were not documented in this young cohort with a maximum age of 30 years and maximum diabetes duration of 15.5 years. This is the first mortality report of a population-based registered cohort of Type 1 diabetic patients for Norway. While still being at increased risk for premature death, this cohort appears to be at decreased risk of early death when compared to a cohort of young diabetic patients from Oslo, Norway diagnosed in 1925-1955, suggesting improvements in the survival of individuals with Type 1 diabetes in Norway.

Adolescent↗
PubMed1991

Flow cytometric analysis of within-strain variation in polysaccharide expression by Bacteroides fragilis by use of murine monoclonal antibodies.

The reactivity of four different monoclonal antibodies (MAbs) with populations of Bacteroides fragilis NCTC 9343, enriched by density gradient centrifugation for a large capsule, small capsule and electron-dense layer (EDL) only visible by electronmicroscopy, was examined. The MAbs reacted strongly with polysaccharides present in both the large capsule- and EDL-enriched populations but not in the small capsule-enriched populations. The pattern of labelling was determined by immunoblotting, immunofluorescence and immuno-electronmicroscopy, and flow cytometry. The MAbs labelled cell membrane-associated epitopes in the large capsule- and EDL-enriched populations and cell-free material in the EDL population. By immunoblotting, ladders of repeating polysaccharide subunits were evident in the EDL population but not in the large capsule population. The proportion of cells labelled within each population was determined by flow cytometry. The reactivity of another MAb with the small capsule population was confirmed by flow cytometry. A qualitative indication of epitope expression was obtained by examination of the flow cytometric profiles. Differential expression of the same saccharide epitope was observed both between and within structurally distinct B. fragilis populations. The MAbs were species-specific and cross-reacted with several recent clinical isolates. These polysaccharides may be relevant to the virulence of B. fragilis.

Animals↗
PubMed1990

Outer membrane proteins of Bacteroides fragilis grown in vivo.

The outer membrane protein (OMP) profiles of four different strains of Bacteroides fragilis, as determined by Coomassie blue stained polyacrylamide gels, were compared after growth in broth culture and in the mouse peritoneal cavity. There was no induction of the expression of large quantities of novel OMP after growth in vivo. Mouse immunoglobulin G and albumin were associated with the bacterial OMP, but could be removed by washing.

Animals↗
PubMed1988

An appraisal of methods used in the examination of retail samples of cows milk.

The use of the methylene blue test for the examination of cows milk was investigated in an inter-laboratory survey. A poor relationship was found between results of these tests and total viable counts. Coliforms were detected in a large number of pasteurized milks, indicating frequent post-pasteurization contamination. No relationship was found between the results of the methylene blue test and the presence of coliforms. Results from this survey highlight the need for reappraisal of the methylene blue test as a statutory method for the examination of milk. A total viable count and coliform test are suggested for providing information regarding dairy hygiene and the quality of the product at the point of retail sale.

Animals↗
PubMed1987

Immunochemical characterization of a polysaccharide antigen of Bacteroides fragilis with an IgM monoclonal antibody.

An IgM mouse monoclonal antibody (McAb) Bf4 was produced to a surface polysaccharide of Bacteroides fragilis NCTC 9343. Immunoblotting showed that McAb Bf4 reacted strongly with a high molecular mass structure which was sensitive to oxidation with periodate but resisted protease treatment. An inhibition enzyme-linked immunosorbent assay (ELISA) indicated that McAb Bf4 did not cross react with the sixteen Bacteroides species and strains tested. Cells of B. fragilis NCTC 9343 recovered from the various interfaces of a Percoll discontinuous density gradient were tested in the inhibition ELISA. Bacteria from the 0-20%, 20-40% and 40-60% interfaces inhibited the ELISA; however, cells from the 60-80% interface did not. Electron microscopy with immunogold labelling showed that McAb Bf4 did not react with the extracellular fibrous network on bacteria recovered from the 0-20% interface, or the extracellular electron dense layer on cells from the 60-80% interface; however, it was associated with a surface structure on cells from the 20-40% interface. Growth in vivo did not enrich for bacteria with this structure.

Antibodies, Monoclonal↗
PubMed1986

Capsulation of in vitro and in vivo grown Bacteroides species.

By centrifugation on a four step Percoll density gradient cells of Bacteroides species could be separated according to the size of extracellular structure. The difference in size was visible by both light and electron microscopy. Two structures were observed on Bacteroides fragilis by electron microscopy, namely a fibrous network and an electron dense layer. An electron dense layer was visible on Bacteroides ovatus only when stained with ruthenium red. B. fragilis cells grown in the mouse peritoneal cavity did not produce a large fibrous network. An electron dense layer was observed on some cells in the presence of ruthenium red stain and cells possessing this layer were phagocytosed in vivo.

Animals↗
PubMed1985

The microbiology of cooked prawns and shrimps on retail sale.

In an inter-laboratory survey, 148 samples of cooked prawns and shrimps were obtained at the point of sale to the consumer. Salmonellae and Vibrio parahaemolyticus were not detected. Yersinia enterocolitica was isolated from three samples. Results for total viable count and presence of Escherichia coli and Staphylococcus aureus complied well with available guidelines for imported cooked prawns, suggesting that the risk of food poisoning from retail samples of these foods in the South of England is minimal.

Decapoda↗
PubMed1984

The microbiology of selected retail food products with an evaluation of viable counting methods.

In an inter-laboratory survey, the pour plate, surface spread, agar droplet and spiral plate methods were used in parallel with the surface drop method for enumeration of micro-organisms in foods. Good agreement was obtained between all surface methods of enumeration, but there was poor agreement between molten agar methods and the surface drop method. A total of 1143 samples of food that were ready for consumption at the point of retail sale were examined. Eight types of food products were chosen: meat pasties, sausage rolls, real-cream slices, synthetic-cream slices, mayonnaise-based coleslaws, faggots, patés and continental sausages. The results of this survey suggest that the upper limit for an acceptable viable count should vary according to the food product. Salmonellae were not isolated on any occasion. Potentially harmful organisms were not isolated at levels expected to constitute a public health hazard. Information concerning the nature of the product, the total viable count, the presence or absence of pathogenic, toxigenic or indicator organisms, the spectrum of the bacterial flora and the relative predominance of each organism must all be considered when assessing the microbiological acceptability of retail 'ready to eat' products.

Bacillus cereus↗
PubMed1984

The growth and survival of capsulate and non-capsulate Bacteroides fragilis in vivo and in vitro.

The growth of capsulate and non- capsulate Bacteroides fragilis in chambers implanted in the mouse peritoneal cavity was compared. Capsulate and essentially non- capsulate (less than 1% capsulate ) populations of B. fragilis strains NCTC9343 and NCTC10584 consistently grew exponentially to greater than 10(9) cfu/ml within 24 h in vivo, and low numbers of capsulate bacteria were maintained in the essentially non- capsulate population; however, the degree of capsulation of the capsulate population decreased by more than 60%. B. fragilis ATCC23745 differed from strains NCTC9343 and NCTC10584 in that growth was unpredictable and only occurred in some of the implanted chambers. Capsule production by cells of strain ATCC23745 varied from chamber to chamber: sometimes the proportion of capsulate cells increased after prolonged implantation. This could occur with either an increase or decrease in viable numbers in vivo and also after in-vitro incubation of this strain in chambers. The survival of capsulate and non- capsulate B. fragilis strains NCTC9343 and ATCC23745 was compared in aerobic and anaerobic conditions in vitro. In anaerobic conditions, capsulate and non- capsulate strain NCTC9343 survived equally well, whereas capsulate ATCC23745 survived better than its non- capsulate variants. Capsulate populations of both strains survived better than non- capsulate in aerobic conditions.

Aerobiosis↗
PubMed1984

Phagocytic and serum killing of capsulate and non-capsulate Bacteroides fragilis.

The relative susceptibilities of capsulate and non- capsulate variants of Bacteroides fragilis to serum and phagocytic killing were investigated. The capsule of B. fragilis did not confer resistance to serum killing. Phagocytic killing of non- capsulate B. fragilis occurred at bacterial concentrations of 1 X 10(6) and 1 X 10(7) cfu/ml. Capsulate B. fragilis organisms were also phagocytosed and killed at a concentration of 1 X 10(6) cfu/ml, but phagocytosis and killing were impaired at a concentration of 1 X 10(7) cfu/ml.

Bacteroides fragilis↗
PubMed1983

Type A and type B attentional responses to aesthetic stimuli: effects on mood and performance.

Recent investigations of the Type A coronary-prone behavior pattern have found that Type A's focus their attention on a central task and actively inhibit attention to peripheral distracting stimuli. This attentional difference has resulted in greater performance for Type A's than for Type B's. However, research on aesthetic stimuli suggests that the focused attention of Type A's may not always be adaptive for solving frustrating cognitive tasks, particularly when paying attention to a peripheral stimulus could enhance performance by reducing negative emotions. Simple, predictable, aesthetic stimuli can have a soothing effect, which reduces negative emotions and enhances performance. The present study found that Type B's had improved affect and performance from attending to a soothing peripheral stimulus (simplex melodies) while working on a frustrating cognitive task. Neither the performance nor the affect of Type A's was influenced by the simplex music, because they apparently suppressed paying attention to these melodies.

Achievement↗