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Biomedical subjects

D G Pritchard

Publications and source records attributed to D G Pritchard.

At least 55 records · Page 3Linked to original sources
PubMed1986

Tuberculosis in East Sussex. IV. A systematic examination of wild mammals other than badgers for tuberculosis.

A detailed investigation of the possible role of wild mammals, other than badgers, in the maintenance of Mycobacterium bovis in an area on the South Downs of East Sussex was carried out over 3 years. Estimates of population sizes were made where possible and minimum sample sizes were selected to be 95% certain of including at least one infected animal if the prevalence was at least 5%. Samples of wild mammals were taken from populations which had the highest potential direct or indirect contact rate with known infected badgers. M. bovis was not isolated from any of the 15 species of wild mammals. It was concluded that badgers are able to maintain M. bovis in an area independently of other species, and that in the area studied other species were not a source of infection for the cattle herds.

Animal Population Groups↗
PubMed1985

Structure of the group-specific polysaccharide of group E Streptococcus.

The structure of the group-specific polysaccharide of group E Streptococcus was determined by methylation, periodate oxidation, and partial methanolysis, and the configuration of the anomeric linkages by 1H- and 13C-n.m.r. spectroscopy. The trisaccharide repeating unit----2)-alpha-L-Rhap-(1----3)-[beta-D-Glcp-(1----2)]-alpha-L -Rhap-(1----was determined.

Carbohydrate Conformation↗
PubMed1985

Seroepidemiological studies of group B Streptococcus type II.

In the course of prospective epidemiological studies of group B streptococcal (GBS) colonization and infection, we surveyed 401 paired maternal and cord sera (obtained at delivery) and 23 sera from patients with systemic type II infection for IgG antibody to GBS type II. Type II carriers were more likely to have antibody (greater than 2 micrograms/ml) than were those carrying other GBS types, whereas noncolonized patients were the least likely to have antibody. The overall prevalence of levels of antibody greater than 2 micrograms/ml was estimated to be approximately 6%, on the basis of assay results of the 401 maternal-cord pairs and adjusted for known-colonization status for the entire population of 8,928 deliveries that occurred during the study period. The majority of patients with infection had antibody levels less than 2 micrograms/ml. Five patients, however, had antibody present at levels ranging from 2.7 to 5.8 micrograms/ml. These findings suggest that "antibody deficiency" was widespread and was not by itself a useful determinant of risk for disease caused by GBS type II.

Antibodies, Bacterial↗
PubMed1985

C-reactive protein binds leishmanial excreted factors.

Excreted factors from Leishmania tropica and Leishmania donovani are precipitated by human and rabbit C-reactive protein. The reaction is calcium dependent and appears to be similar to that reported to occur between C-reactive protein and various galactans. The absence of phosphate and N-acetyl galactosamine suggests that the reaction is not the result of any similarity of the excreted factors to pneumococcal C-polysaccharide.

Antigens, Protozoan↗
PubMed1984

Interaction of group B streptococcal type-specific polysaccharides with wheat germ agglutinin and other lectins.

The group B streptococci (GBS) are known to have type-specific polysaccharides rich in N-acetylneuraminic acid end groups, which are thought to be important immunological determinants. Wheat germ agglutinin (WGA) has affinity for N-acetylneuraminic acid as well as N-acetylglucosamine, and readily precipitates the type but not the group polysaccharide. A WGA-Sepharose affinity column was used to isolate complete type polysaccharides of representative strains of the 4 major GBS types. WGA, other lectins, and rabbit antisera were then used to characterize the products of various extraction procedures and chemical degradations, including mild acid hydrolysis and treatment with neuraminidase. Results of lectin binding studies were consistent with proposed chemical structures of types Ia, Ib and II. Differences were noted, however, between the cross-reactive antigens of pneumococcus type 14 and the desialated GBS type III polysaccharide. Although structurally similar, indirect evidence from lectin binding studies suggest that these antigens may not be identical.

Animals↗
PubMed1984

Characterization of the group-specific polysaccharide of group B Streptococcus.

The group-specific polysaccharide of the group B Streptococcus was isolated by nitrous acid extraction followed by gel filtration on Sepharose 6B and chromatography on DEAE-Bio-Gel A. It was composed of rhamnose, galactose, N-acetylglucosamine, and glucitol phosphate. Mild periodate oxidation of the polysaccharide resulted in a rapid reduction in molecular weight, indicating that the glucitol was located in the backbone of the polymer. High-resolution 31P NMR showed the presence of a single type of phosphodiester bond in the molecule. Methylation analysis and several specific chemical degradations were done to determine sugar linkages. The basic structure of the group B polysaccharide consists of a backbone of 2-linked rhamnose, 2,4-linked rhamnose, and glucitol phosphate, and side chains of rhamnose(1----3)galactose(1----3)N-acetylglucosamine linked to the 4-position of a rhamnose in the backbone.

Chemical Phenomena↗
PubMed1984

LPS regulation of the immune response: separate mechanisms for murine B cell activation by lipid A (direct) and polysaccharide (macrophage-dependent) derived from Bacteroides LPS.

Lipopolysaccharide (LPS) derived from Bacteroides fragilis has been reported to stimulate mitogenic responses in spleen cell cultures from the classical LPS-hyporesponsive C3H/HeJ mouse strain; however, we have shown that purified splenic B cells from C3H/HeJ mice are hyporesponsive to phenol-water extracted LPS from B. fragilis ATCC 25285 (B-LPS). In the present study, B-LPS and its purified lipid A and polysaccharide components were tested for their ability to induce mitogenic and polyclonal IgM synthesis in spleen cell and purified splenic B cell cultures from classical LPS-responsive and -hyporesponsive mice. Mitogenic responses to B-LPS and E. coli K235 LPS(Ph) of whole spleen cells (2 X 10(5) cells/culture) or purified B cells (5 X 10(5) cells/culture) from classical LPS-responsive mouse strains (C3H/HeN, BALB/c, C57BL/6J, C57BL/10Sn, and DBA/2), F1 mice (derived from crosses between LPS responsive and C3H/HeJ mice), and classical LPS-hyporesponsive mice (C3H/HeJ and C57BL/10ScN) were high, intermediate, and low, respectively. When a higher number of whole spleen cells (5 X 10(5) cells/well) were cultured, B-LPS induced high mitogenic responses in C3H/HeN, intermediate responses in F1, and lower but significant responses in C3H/HeJ cultures. Similar results were obtained when polyclonal IgM synthesis was assessed in cultures containing 1 X 10(6) cells/culture. In contrast, the purified lipid A component of B-LPS failed to induce mitogenic responses in either whole spleen or purified B cell cultures. The addition of purified splenic B cells from C3H/HeJ mice to C3H/HeN or C3H/HeJ splenic adherent cells resulted in mitogenic responses to B-LPS, implying that the hyporesponsiveness to B-LPS seen in whole spleen cell cultures from C3H/HeJ mice at the lower cell concentration was due to limiting numbers of M phi. When splenic B cells and M phi from either C3H/HeN or C3H/HeJ mice were incubated with the lipid A or the polysaccharide moiety of B-LPS, lipid A induced mitogenic responses only in C3H/HeN cultures, whereas the polysaccharide moiety induced similar responses in both C3H/HeN and C3H/HeJ cultures. These results suggest that Bacteroides lipid A does not stimulate B cells from the classical LPS-hyporesponsive C3H/HeJ mouse strain, whereas the polysaccharide moiety of B-LPS is biologically active and mediates B cell stimulation via M phi.

Animals↗
PubMed1983

Protection of mice from experimental infection with type III group B Streptococcus using monoclonal antibodies.

Mouse hybridoma antibodies of several major classes against group B streptococcus type III have been produced. Mice were immunized with either whole heat-killed or acid-treated organisms to obtain antibodies against both the complete (sialated) or incomplete (nonsialated) forms of the type III polysaccharide. Resulting monoclonal antibodies showed exclusive specificity for either the complete or incomplete antigen. The ability of these antibodies to protect mice from a lethal challenge of live type III organisms was tested with a mucin model that permitted use of very small inocula given intraperitoneally with antibody and mucin. Antibodies specific for the nonsialated antigen were not protective, whether of IgM, IgG2a, or IgG3 isotypes. Antibodies specific for the complete antigen were, however, highly protective, including monoclonals of IgM, IgG2a, and IgA isotypes. These mouse monoclonal antibodies against group B streptococci that are directed against either complete or incomplete antigenic determinants, and include isotypes other than IgM, should be particularly useful for studying the mechanism of protection against experimental infection.

Animals↗
PubMed1983

Haemorrhagic syndrome of cattle associated with the feeding of sweet vernal (Anthoxanthum odoratum) hay containing dicoumarol.

An outbreak of a haemorrhagic diathesis in cattle fed home produced hay is described. A similar syndrome was reproduced experimentally in calves by feeding them the hay. The experimental disease was characterised by increased prothrombin and partial thromboplastin times while the leucocyte and erythrocyte counts remained normal until the terminal haemorrhage. The calves ate well and grew well until the rapid onset of progressive weakness, stiff gait, mucosal pallor, tachycardia, tachypnoea and haematomata ending in sudden death. The absence of blood coagulation was seen at necropsy while petechial, ecchymotic and free haemorrhages were found in most organs. Particularly striking were massive ecchymotic haemorrhages on the peritoneal surface of the rumen, a bloody, gelatinous mass enveloping each kidney and extensive bruising, haemorrhage and haematomata in the subcutis of the limbs. In a second feeding trial the effects of various preparations of vitamin K1 and vitamin K3 were investigated. Oral administration of large quantities of vitamin K1 reduced the elevated prothrombin time; vitamin K3 acted less consistently. Analysis of the hay for trichothecene mycotoxins was negative but floral analysis revealed that sweet vernal grass (Anthoxanthum odoratum) comprised about 80 per cent of the hay. Dicoumarol was detected in the hay and in the serum and ruminal contents of the experimental calves. The diagnosis, treatment, control and importance of this syndrome in the United Kingdom are discussed.

Animal Feed↗
PubMed1983

Immunization of animals with gal E mutants of "Salmonella typhimurium".

A galactose epimeraseless (gal E) mutant of Salmonella typhimurium was investigated in mice, calves and poultry for its suitability as a live vaccine. In mice a very highly significant difference in the mortality rates was observed when vaccinated and non-vaccinated animals were challenged with virulent strains of S. typhimurium and S. dublin. In calves, doses of 10(6) and above of gal E mutant injected subcutaneously provided highly significant protection in terms of mortality and prevalence of symptoms when challenged orally with S. typhimurium. Renal lesions were found in a number of calves and studies were undertaken to investigate their pathogenesis. The results of these studies suggested that gal E. mutants were unlikely to produce the renal lesions. When day-old chicks were vaccinated orally with live gal E mutant of S. typhimurium and challenged orally 14 days later there was a statistically significant reduction in faecal shedding, in the salmonella carrier status at slaughter and in the numbers of salmonellae in the broiler house environment. The vaccine however, had a significant effect on the live weight gain of the birds.

Animals↗
PubMed1981

Effect of air filtration on respiratory disease in intensively housed veal calves.

The effect of a recirculating air filter unit on concentrations of airborne bacteria, clinical and subclinical respiratory disease and production performance of veal calves was studied over a period of one year. Six groups of 28 calves in sheds with internally filtered air were paired by age and time of entry with six similar groups in non-filtered sheds; they were also compared with 23 groups, each of 28 calves, in non-filtered sheds present in the unit during the period of study. Mean aerial bacteria concentration in filtered sheds was reduced by 44.9 per cent (P less than 0.0001). A comparison of unfiltered and filtered sheds on a paired basis showed that the number of animals requiring antibiotic treatment for respiratory disease was reduced by 19.3 per cent (P greater than 0.05). The number of repeat courses of treatment was reduced by 28.9 per cent (P less than 0.025) and total antibiotic usage was reduced by 34.8 per cent (P less than 0.025). At slaughter the average area of lung consolidation in calves from filtered sheds was reduced by 38.4 per cent (P less than 0.025. When all the 644 calves in the unit from 23 non-filtered sheds were compared with the 168 calves in the six filtered sheds the reduction in first treatments, repeat courses and total treatments were 19.7 per cent (P less than 0.025), 28.3 per cent (P less than 0.025) and 31.6 per cent (P less than 0.025) respectively. Air filtration was therefore associated with a reduction in both incidence and severity of clinical and subclinical disease in calves. Both treatment for respiratory disease and area of lung consolidation at slaughter were directly related to reductions in daily weight gain. The economic effect of respiratory disease on veal calves is briefly discussed.

Air Microbiology↗