Immunological clearance of 75Se-labelled Trypanosoma brucei in mice. III. Studies in animals with acute infections.

Using trypanosomes labelled with [75Se]-methionine a series of experiments was conducted to investigate antibody production in mice with acute fulminating T. brucei infections. As measured by the hepatic uptake of radiolabelled parasites, we were unable to demonstrate any evidence of antibody-mediated uptake by the liver in such mice.

Microelisa test for detecting antibodies to rinderpest virus antigens.

A microplate enzyme-linked immunosorbent assay (ELISA) was developed which detected antibodies to a soluble antigen prepared from sonicated rinderpest virus-infected cells. The ELISA detected titres of antibody to the virus in the sera of cattle 3 weeks after immunisation with tissue culture rinderpest virus vaccine which were similar to those detected by the virus neutralisation test. The ELISA test shows potential as a rapid and economic technique for screening large numbers of sera for antibody to rinderpest virus.

Immunological clearance of 75Se-labelled Trypanosoma brucei in mice. II. Mechanisms in immune animals.

Using trypanosomes labelled with [75Se]-methionine a series of experiments was conducted to investigate the respective roles of antibody, macrophage activtion and complement in the removal of trypanosomes from the circulation of immune mice. It was found that clearance in such animals is largely accomplished by antibody-mediated hepatic phagocytosis, which, at least in passively immunized animals, is dependent on opsonization involving C3. No evidence was found to suggest that intravascular lysis or activated macrophages are involved in immune clearance.

Propagation of sepsis in vascular grafts.

Clinical studies have stated that sepsis tends to remain localized at the point of origin in a patent arterial synthetic graft. We have demonstrated in the pig model that in the acute phase, infection will propagate distally in both thrombotic and patent grafts. The propagation of infection is probably intraluminal.

Genetic resistance to Trypanosoma congolense infections in mice.

The mechanisms of genetic resistance or "trypanotolerance" to infection with Trypanosoma congolense were investigated in two strains of mice. One strain C57BL, is outstandingly resistant to most stabilates of T. congolense and can survive for over 80 days, whereas CFLP, in common with most other strains, generally succumbs in less than 20 days.

Evidence of prostaglandin involvement in blastocyst implantation.

Delayed-implantation mice were used to test for local implantation induction effects of prostaglandins E2 and F2 alpha. Evidence of implantation was gathered by microdissection of implantation sites and by scanning electron microscopy. Indomethacin was tested for the ability to interfere with the mechanisms of estrogen-induced, normal implantation.

Evaluating the potential eye irritancy of shampoos.

Synopsis Experience in a large manufacturing unit showed that splashes of undiluted shampoo only produced transient effects in the eyes of production and packaging staff; over the same period, very few complaints of eye irritation were received from shampoo users, none of which were of a serious nature. Predictive testing is needed to make sure that new formulations are not severe eye irritants though rabbit eye testing may tend to exaggerate the likely human response. Detergent concentration is the principal factor influencing findings in the rabbit eye and an active matter content of 2.

Immunological clearance of 75Se-labelled Trypanosoma brucei in mice. I. Aspects of the radiolabelling technique.

A reliable and simple technique for the in vivo labelling of Trypanosoma brucei with [75Se]-methionine was developed. Between 97 and 99% of the radioactivity was protein bound in the trypanosomes and spontaneous elution in vitro was less than 10% over 4 h. The fate of the labelled trypanosomes after i.

Effect of chronic Trypanosoma brucei infection on the course of louping ill virus infection in mice.

The course of louping-ill virus infection in mice chronically infected with Trypanosoma brucei was investigated. The mean survival time of mice infected with virus alone was 10.2 days, compared to 12.

Transfer of matching performance in pigeons.

Three pigeons were given extensive training on three-key simultaneous matching problems using geometric-form and hue stimuli. After acquisition of matching, the birds were tested with pairs of stimuli involving one or both novel members. Matching during the test stimuli occurred less often than during the later stages of the acquisition phase, but more often than would occur if no transfer had taken place.

Immunosuppression in bovine trypanosomiasis: studies with louping-ill vaccine.

The antibody response to louping-ill virus vaccine was examined in mice infected with Trypanosoma brucei and T congolense, and in Ethiopian cattle experimentally infected with T brucei, T congolense and T vivax. In mice the antibody response was completely suppressed, while in cattle infected with T congolense and T vivax the antibody response to the vaccine was only 10 per cent that of uninfected animals. In contrast, the response of cattle infected with T brucei was not significantly reduced, and this was attributed to their relatively light and transient parasitaemias.

The susceptibility of strains of mice to infection with Trypanosoma congolense.

The survival times of a number of strains of mice after infection with a stabilate of Trypanosoma brucei or of T congolense were examined. The mean survival times of all the strains when infected with T brucei TREU 667 ranged from 27 to 63 days. Greater disparity was observed after infection with T congolense GVR1 where the mean survival time ranged from seven (BALB/c) to 74 days (C57 Bl).

The establishment of a laboratory colony of Ixodes holocyclus.

A laboratory colony capable of producing annually 3000 female Ixodes holocyclus was maintained for 3 years. Guinea-pigs were used for larval feeding and bandicoots for nymphs and adults. The methods and equipment employed are described in detail.

H2-producing bacteria in digesting sewage sludge isolated on simmple, defined media.

Twenty percent of bacteria isolated on simple, defined anaerobic media produced H2. Eighty-four percent of these were isolated on glucose. All were Enterobacteriaceae, primarily Citrobacter.

Attempted protection of zebu cattle against trypanosomiasis using a multi-stabilate vaccine.

The protective value of double vaccination with 11 recently isolated stabilates of Trypanosoma congolense given either as live or dead organisms, followed by trypanocidal therapy, was assessed in zebu cattle subsequently challenged by nine of the original stabilates. Both vaccination regimens failed to prevent the animals becoming parasitaemic and eventually succumbing to the infection, although the mean survival times and prepatent periods of the calves which received the live vaccine were longer than those of both the groups which had received the dead vaccine and the challenge controls.