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Biomedical subjects

D G Pritchard

Publications and source records attributed to D G Pritchard.

At least 37 records · Page 2Linked to original sources
PubMed1988

The haematological values of European badgers (Meles meles) in health and in the course of tuberculosis infection.

Captive, healthy, adult badgers have blood containing haemoglobin at 13.3 g/dl, and 8.4 x 10(12)/l red cells with an MCV of 46.2 fl and an MCH of 15.6 pg. They have 5.1 x 10(9) white cells/l of which 3.29 x 10(9) are polymorphs, 1.49 x 10(9) are lymphocytes, 0.26 x 10(9) are monocytes, 0.07 x 10(9) are eosinophils and 0.01 x 10(9) are basophils. These values are somewhat less in adult animals just trapped from the wild, and are lower still in wild cubs. Changes associated with tuberculosis are a rise, and then a fall in red blood count and white blood count, an increase in the proportion of polymorphs and monocytes and a fall in lymphocytes late in the disease. This picture is similar to that seen in widespread, disseminated, tuberculin negative, tuberculosis in humans, a type of disease similar to that occurring in many badgers. BCG vaccination of badgers did not produce any measurable change in the blood picture.

Animals↗
PubMed1988

Seroepidemiology of group B Streptococcus type II antibody specificity.

The specificity of human antibodies for the two major sidechain determinants of the type II group B streptococcal (GBS) polysaccharide was examined in 90 pairs of maternal and cord sera. Using an ELISA system, total antibody was measured against the complete (sialylated) type II antigen and the proportion of antibody against the galactose determinant was estimated by inhibition with free beta-methylgalactopyranoside. Mothers colonized by type II or by other GBS types had higher levels of total specific antibody (means, 3.3 and 4.7 micrograms/ml, respectively) than those not colonized (mean, 2.2 micrograms/ml). Cord sera averaged 1-2 micrograms/ml lower than maternal sera. Colonization with GBS was also associated with higher levels against the galactose determinant (mean, 1.5 micrograms/ml, compared to 0.7 micrograms/ml for those not colonized). The distribution of specificities favoured antibodies against the sialic acid determinant in maternal but not cord sera. Specificity as well as antibody level may play a role in the epidemiology of GBS type II.

Antibodies, Bacterial↗
PubMed1988

Specificity of monoclonal antibodies against group B streptococcus type II and inhibition of their binding by human secretions.

Mouse monoclonal antibodies against the type-specific polysaccharide antigen of type II group B Streptococcus may be divided into two general groups based on their antigen-binding properties. One group of antibodies binds to both intact and desialylated type II antigen and the binding can be inhibited by beta-galactopyranosides. The second group of antibodies react only with intact type II polysaccharide and are not inhibited by beta-galactopyranosides. The binding of antibodies of the first group can also be inhibited by carbohydrate components of normal human secretions that share structural similarities with the type II polysaccharide. The binding of antibodies of one specificity precluded the binding of antibodies of the other specificity, apparently by competing for binding sites within a combining area that includes both determinants.

Animals↗
PubMed1987

Structure of the serotype f polysaccharide antigen of Streptococcus mutans.

The structure of the serotype f polysaccharide antigen of Streptococcus mutans was determined by methylation analysis, periodate oxidation, and partial methanolysis, and the configuration of the anomeric linkages by 13C-n.m.r. spectroscopy, indicating the trisaccharide repeating unit----3)-alpha-L-Rhap-(1----2)-[alpha-D-Glcp-(1----3)]-alpha-L-+ ++Rhap- (1----. The structure of the backbone of the polysaccharide was confirmed by demonstrating immunological identity between the product of Smith degradation of the S. mutans serotype f antigen and the group A-variant streptococcal polysaccharide.

Carbohydrate Conformation↗
PubMed1987

Proton nuclear magnetic resonance measurement of the amide hydrogen exchange rates of group A streptococcal polysaccharide in H2O.

The solvent exchange rates of the acetamido hydrogen of the 2-acetamido-2-deoxy-beta-D-glucopyranosyl unit of group A streptococcal polysaccharide dissolved in H2O have been measured and compared with the corresponding exchange rates in the solvated model compound 1-O-methyl-2-acetamido-2-deoxy-beta-D-glucopyranoside. Amide hydrogen exchange rates were measured at 25 degrees C over a wide pH range by a combination of two separate NMR techniques: the transfer of solvent saturation and the amide hydrogen saturation recovery NMR experiments. The data indicate that the acetamido hydrogen essentially exists in a solvated environment and that its contribution to the conformational stability of this polysaccharide through intramolecular hydrogen bonding is negligible.

Amides↗
PubMed1987

The immune response in two populations of wild badgers naturally infected with bovine tubercle bacilli.

This study describes the immune responses of two defined badger populations; one from East Sussex and another from Staffordshire. The mean in vitro lymphoproliferative response, of all infected badgers from both areas, to Glaxo BCG, was significantly greater than that of healthy animals. The infected badgers had significantly higher antibody levels against mycobacterial antigens, especially New Tuberculin, than did the healthy animals. All the healthy and tuberculous badgers from the Staffordshire area were invariably unreactive to the various preparations used for skin-testing. However, in the East Sussex area, positive reactions were obtained in 10 out of 37 healthy and 7 out of 10 infected animals. This is the first account of positive skin tests in free living badgers. These results support the concept that badgers infected with bovine tubercle bacilli pass through an immunological spectrum throughout much of which they are unlikely to be important sources of infection. In the early stages, tubercle bacilli are excreted from infected wounds, whereas in the later stages, failure of cell-mediated immunity results in excretion of tubercle bacilli from other sites and the badger becomes a potent source of infection.

Animals↗
PubMed1987

Experimental infection of badgers (Meles meles) with Mycobacterium bovis.

The intradermal inoculation of four badgers with small numbers of Mycobacterium bovis resulted in localized lesions with ulceration which slowly healed by 5 months after inoculation. Lesions of generalized tuberculosis were seen in three badgers, one of which died at 17 months post-inoculation and in the remaining two killed 22 months post-inoculation. In the fourth badger lesions were confined to the draining lymph node of the inoculation site but M. bovis was isolated from the liver. Monthly clinical sampling of faeces, urine, tracheal aspirate and inoculation site exudates detected only the excretion of M. bovis from the inoculation site of one badger. There were marked seasonal variations in body weight but significant weight loss was observed during the second year in all four badgers, particularly prior to death. Four badgers inoculated intratracheally with a similar inoculum of M. bovis and another two control badgers showed no evidence of infection with M. bovis.

Animals↗
PubMed1987

The immunological consequences of challenge with bovine tubercle bacilli in badgers (Meles meles).

Optimal conditions were determined for performing antibody measurements (ELISA), lymphocyte transformation tests and, to some extent, skin tests in badgers. These parameters, together with the bacteriological and pathological studies reported previously (Pritchard et al. 1987), were used to follow the course of intradermal and intratracheal challenge of badgers with bovine tubercle bacilli. Two challenge doses were used for each route of infection and two animals received each dose. None of the four animals challenged by the intratracheal method showed any evidence of infection, suggesting that adult badgers may have some resistance to challenge by this method. All four animals challenged intradermally developed lesion of tuberculosis. Immunologically the disease passed through three phases. There was an early phase in which lymphocyte transformation to whole BCG steadily and significantly increased, and skin tests to tuberculin became positive but there was little change in antibody levels. This was followed by an intermediate phase of variable skin responses, fluctuating lymphocyte transformation and significant increase in antibody levels. The final phase, which was only seen in two animals with extensive disease, was associated with changing skin reactions and falling lymphocyte responses, together with a sudden increase in antibody levels. This paper presents the first formal evidence of cell-mediated immunity to tuberculosis in the badger, which may delay onset and prolong the survival of challenged animals.

Animals↗
PubMed1986

Problems associated with the serological diagnosis of Leptospira interrogans serovar hardjo infection in bovine populations.

Data combining sequential bacteriology and serology from a longitudinal study of a dairy herd were used to demonstrate the limitations of serology as a diagnostic method in cross-sectional sampling of bovine populations. Whole-herd point serological prevalences showed considerable variation over a two-year sampling period (38.8 to 76.2 per cent), and this was mainly due to varying age-specific prevalence. Owing to the rapid decline in titres and the varying persistence of infection, point serological prevalences failed to approximate to cumulative infection rates (either past or present) at different times of the year. A higher estimate of the number of susceptible animals in the herd than is the case results in inaccurate information on true incidence rates and can confuse assessments of the susceptibility of different age groups, especially if only small numbers are sampled. A sampling exercise demonstrated that a 10-cow sample usually provided little useful information other than establishing the presence or absence of hardjo in the herd. Increasing the sample size markedly improved epidemiological information, investigations of clinical disease, assessments of vaccination needs and public health tracebacks. Preferably 10 sera from each of the yearling, first calver, second calver and older age groups should be tested. Serology was an inadequate indicator of infection in individual animals. Group geometric mean titres taken from a mean serological response curve were shown to have limited application in the interpretation of field data, unless infection had occurred in the previous two months.

Animals↗
PubMed1986

Characterization of the serotype e polysaccharide antigen of Streptococcus mutans.

The structure of the Streptococcus mutans serotype e polysaccharide was studied in order to determine the chemical basis of the immunological cross-reactions observed between it and the streptococcal group E polysaccharide. The chemical structure was established using methylation analysis, periodate oxidation, partial methanolysis and 13C NMR spectroscopy. The polysaccharide was found to consist of a polyrhamnose backbone of alternating 2- and 3-linked alpha-L-rhamnose units and sidechain beta-D-glucosyl units linked to the 2-position of rhamnose units in the backbone. This structure of the oligosaccharide repeating unit of the S. mutans serotype e polysaccharide was identical to that of the group-specific polysaccharide of group E Streptococcus. Possible explanations for the previously reported differences in these two polysaccharides are discussed.

Chemical Phenomena↗
PubMed1986

Tuberculosis in East Sussex. I. Outbreaks of tuberculosis in cattle herds (1964-1984).

The history and epidemiology of bovine tuberculosis in cattle herds in East Sussex are described. Since 1960, following the compulsory eradication scheme for tuberculosis, the incidence of herd infection has been low. The epidemiological features of herd infection have been sporadic incidents, with only small numbers of cattle becoming infected in the majority of incidents. There was no evidence of endemic Mycobacterium bovis infection in the cattle population in East Sussex in recent years, but a low risk of infection for cattle on the South Downs, from badgers, was apparent.

Animals↗
PubMed1986

Tuberculosis in East Sussex. II. Aspects of badger ecology and surveillance for tuberculosis in badger populations (1976-1984).

Following the disclosure of Mycobacterium bovis infection in badgers in East Sussex in 1976, badgers have been examined from and around farms on which cattle have become infected, but with no other attributable source of infection. These farms are confined to the downland of the south-west of the county and M. bovis has been confirmed in badger populations utilising their land. The available evidence indicates that M. bovis infection in badgers is also confined to this area. A detailed study in one area on the South Downs suggested that M. bovis is endemic in the badger population and therefore presents a continued risk for cattle occupying the area.

Animals↗
PubMed1986

Tuberculosis in East Sussex. III. Comparison of post-mortem and clinical methods for the diagnosis of tuberculosis in badgers.

Following epidemiological and ecological studies of a defined badger population in an area of East Sussex, removal of all badgers by cage trapping was attempted. Trapping was incomplete due to the activities of protesters. Forty-seven badgers were caught from the eight social groups. All badgers were examined clinically and samples of faeces, urine and tracheal aspirate were taken, together with swabs from any bite wounds, for bacteriological examinations. Forty-five animals were skin tested using whole killed cells of Mycobacterium bovis strain AN5, bovine PPD Weybridge and new human tuberculin. Skin test results were recorded after 24 and 72 h. All badgers were killed and subjected to a post-mortem and bacteriological examination. M. bovis was detected in 10 (21.3%) badgers at post-mortem and in 2 badgers from clinical samples. Four social groups were infected. Positive skin test results were recorded at 72 h with bovine PPD (2 micrograms and 20 micrograms/ml), strain AN5 (1 mg/ml) and human tuberculin (2 micrograms/ml), but not with human tuberculin at 20 micrograms/ml. Histological sections of the skin test reactions showed the cellular types typical of delayed-type hypersensitivity. The skin test reactions observed were neither sensitive nor specific enough to be of practical value.

Age Factors↗