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Biomedical subjects

P Stevenson

Publications and source records attributed to P Stevenson.

13 recordsLinked to original sources
PubMed1992

Application of a monoclonal antibody-based antigen detection enzyme-linked immunosorbent assay (antigen ELISA) for field diagnosis of bovine trypanosomiasis at Nguruman, Kenya.

A monoclonal antibody-based, enzyme immunoassay (antigen ELISA) for the detection of species-specific invariant antigens of Trypanosoma congolense, T. vivax or T. brucei in the serum of infected animals was evaluated as a means of diagnosis using bovine field sera from a trypanosomiasis endemic area, Nguruman, Kenya. Circulating trypanosome antigens were detected in 126 (96.2%) of 131 serum samples from animals with parasitologically confirmed diagnosis: 74.8% were positive for antigens of two or three trypanosome species, while 21.4% tested positive for one trypanosome species. When 70 sera from animals (at Nguruman), which had tested negative for trypanosomes by the buffy coat technique, were tested, 35 (50.0%) of them were shown to be antigen-ELISA positive: 24 (34.3%) showing infection with a single species and 11 (15.7%) with mixed infections. The predominant trypanosome species diagnosed in the two herds by antigen ELISA was T. vivax, which was detected in 133 (82.6%) of the 161 sera that tested positive for antigens, followed by T. congolense in 122 (75.8%) sera, with 109 (67.7%) showing evidence of mixed infections with two or three trypanosome species. In single infections, T. vivax exceeded T. congolense by a ratio of 2:1, with T. brucei accounting for less than 1.0%. Evidence for the specificity of the test was provided by analysis of field sera from 100 cattle, from a trypanosomiasis-free area, infected with other haemoparasites (anaplasmosis, babesiosis and theileriosis), which all tested negative in the assay.

Animals↗
PubMed1992

Common antigenic domains in transferrin-binding protein 2 of Neisseria meningitidis, Neisseria gonorrhoeae, and Haemophilus influenzae type b.

There is now considerable evidence to show that in the Neisseria and Haemophilus species, membrane receptors specific for either transferrin or lactoferrin are involved in the acquisition of iron from these glycoproteins. In Neisseria meningitidis, the transferrin receptor appears to consist of two proteins, one of which (TBP 1) has an M(r) of 95,000 and the other of which (TBP 2) has an M(r) ranging from 68,000 to 85,000, depending on the strain; TBP 2 binds transferrin after sodium dodecyl sulfate-polyacrylamide gel electrophoresis and electroblotting, but TBP 1 does not do so. The relative contributions of these two proteins to the binding reaction observed with intact cells and to iron uptake are presently unknown. However, they are being considered as potential components of a group B meningococcal vaccine. Analogous higher- and lower-molecular-weight proteins associated with transferrin binding have been found in N. gonorrhoeae and Haemophilus influenzae. Previous work with polyclonal antibodies raised in mice with whole cells of iron-restricted N. meningitidis showed that the meningococcal TBP 2 exhibits considerable antigenic heterogeneity. Here, we report that antiserum against purified TBP 2 from one strain of N. meningitidis cross-reacts on immunoblotting with the TBP 2 of all meningococcal isolates examined, as well as with the TBP 2 of N. gonorrhoeae. This antiserum also cross-reacted with the TBP 2 of several strains of H. influenzae type b, thus showing the presence of common antigenic domains among these functionally equivalent proteins in different pathogens; no cross-reaction was detected with a purified sample of the human transferrin receptor.

Animals↗
PubMed1991

Control of Fasciola gigantica with triclabendazole in Indonesian cattle.

The efficacy of triclabendazole (TCBZ) against natural infections with Fasciola gigantica was evaluated in a field study using 102 Indonesian cattle. The animals were divided into two groups; one received TCBZ at 12 mg/kg orally every eight weeks for one year while the other remained untreated. Relative to controls the Fasciola faecal egg count in treated animals was significantly reduced (P less than 0.01) to almost zero at all observations. There were no differences between the groups in blood values and body mass gain. Plasma glutamate dehydrogenase (GLDH) levels in treated animals were reduced to within normal values, whereas those in controls remained above normal throughout. Although plasma gamma glutamyl transferase (GGT) levels remained within the normal range in both groups they were consistently higher in control than in treated animals. However, both GLDH and GGT levels in control animals were considerably lower than those reported by others in experimental low-level chronic fasciolosis, which suggests that only mild liver damage was caused by small numbers of F. gigantica in these animals. In addition to considerations of disease prevalence and economic data from abattoirs, control strategies for fasciolosis in Indonesian cattle require an evaluation of losses due to subclinical disease.

Animals↗
PubMed1990

Homidium bromide as a chemoprophylactic for cattle trypanosomiasis in Kenya.

Homidium bromide was used in a strategic chemoprophylactic regime to control trypanosomiasis in Boran cattle in Kenya. Trypanosome infection rates in cattle receiving homidium bromide prophylaxis were compared with those in control cattle which received no prophylaxis but were treated with diminazene aceturate when infected. Homidium bromide was administered twice during the year after which no infections were detected for periods of nineteen weeks and seventeen weeks respectively. The drug sensitivity of the infecting trypanosomes is believed to be a major factor in determining the duration of prophylaxis.

Animals↗
PubMed1979

Toxocara and ascaris infection in British pigs: a serological survey.

A serological survey of growing pigs from farms throughout Great Britain revealed that antibodies to toxocara and ascaris larval antigens were present in 4.5 per cent and 39.3 per cent respectively. Heavy infection with toxocara occurred only rarely and it is considered that this parasite is unlikely to be an important cause of chronic focal interstitial hepatitis. Antibodies to both nematodes were detected more frequently in heavy hogs than in pigs of lighter weight. Reginal differences in the prevalence of antibodies were also observed.

Animals↗
PubMed1979

The influence of environmental temperature on the rate of development of Ascaris suum eggs in Great Britain.

The rate of development of Ascaris suum eggs was recorded during 18 months in England. Every second or third week unembryonated eggs were placed in an unheated animal house and their development was observed at weekly intervals. Eggs underwent no development during November to May. Embryonation was most rapid during June, July and August. The shortest time for eggs to reach the infective stage was two weeks in 1976 and four weeks in 1977. A relationship was apparent between the rate of development of eggs and the seasonal occurrence of pigs in chronic focal interstitial hepatitis, a condition associated with infection by A suum larvae.

Animals↗
PubMed1977

Toxocara infection in pigs. The use of indirect fluorescent antibody tests and an in vitro larval precipitate test for detecting specific antibodies.

An in vitro larval precipitate test using second-stage Toxocara canis larvae and an indirect fluorescent antibody (IFA) test employing cuticles of T. canis larvae as antigen were evaluated using antisera produced in pigs experimentally infected with T. canis, T. cati, Ascaris suum, Toxascaris leonina and Parascaris equorum. The former test was both specific and sensitive and is suggested as a reliable and simple method of detecting Toxocara antibodies in pigs. The latter test was considered unsuitable because of cross-reactions that occurred when sera from pigs infected with other ascarids were tested. An IFA test for Ascaris antibodies, employing cuticles of A. suum larvae as antigen, is described. The degree of specificity of this test suggests that it may be of value in the detection of antibodies to Ascaris in pigs under natural conditions.

Animals↗
PubMed1976

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