Effect of prior sporidesmin intoxication on the pancreopathy associated with zinc oxide toxicity.

Aim: To demonstrate the effect of prior sporidesmin-induced liver injury on the pancreopathy of zinc-induced toxicity.

Methods: Four groups, each of 15 sheep, were given 2 x 2 treatments of sporidesmin (0.3 mg/kg bodyweight spread over 3 consecutive days prior to zinc) and zinc (200 mg Zn/kg bodyweight as ZnO spread over 24 days) starting 4 days after the end of sporidesmin dosing.

Urinary excretion of immunoreactive sporidesmin metabolites in sheep in relation to factors influencing susceptibility to sporidesmin intoxication.

Aim: To study the urinary disposition of orally administered sporidesmins A and D in sheep and identify factors influencing their kinetics, particularly the influence of breeding for resistance and susceptibility to sporidesmin, the mycotoxin responsible for the hepatogenous photosensitisation, facial eczema.

Methods: A competitive ELISA was used to monitor urinary output of immunoreactive metabolites after the intraruminal administration, to female Romney sheep, of either sporidesmin A or sporidesmin D, the nontoxic analogue. Preliminary characterisation of metabolites was carried out using HPLC with fractions monitored by ELISA.

Effect of the mycotoxins penitrem, paxilline and lolitrem B on the electromyographic activity of skeletal and gastrointestinal smooth muscle of sheep.

The electromyographic (EMG) activity of skeletal muscle was investigated as a method of recording the tremorgenic activity of the mycotoxins penitrem, paxilline and lolitrem B in sheep. EMG recordings were made concurrently from the abomasal antrum and duodenum to study the effects of these tremorgens on smooth muscle of the gut. Penitrem (2.

A simple gag for the intragastric dosing of guinea pigs (Cavia porcellus).

A simple gag has been designed and tested which enables the intragastric intubation of the guinea pig by one person without the use of sedation or light anaesthesia. The system described was used successfully for the daily dosing of materials to 7 guinea-pigs for 14 days without discomfort, aspiration or any injury to the upper gastro-intestinal tract.

Sequential changes in the development of the pancreatic lesion of zinc toxicosis in sheep.

Forty-two 10-month-old castrated male sheep were dosed with zinc oxide to study the pathogenesis of the pancreatic lesion. For 4 weeks, the sheep were dosed three times per week with 240 mg Zn (as ZnO)/kg body weight/dose, and seven groups of six sheep each were necropsied at 4, 7, 14, 21, 28, 56, and 112 days after the start of dosing. Plasma zinc concentrations rose rapidly to 2.

Facial eczema in goats: the toxicity of sporidesmin in goats and its pathology.

Groups of six goats were orally dosed with sporidesmin at rates of 0.3, 0.6, 1.

Carcinogenicity of bracken fern (Pteridium esculentum) in New Zealand.

Bracken fern (Pteridium esculentum) was harvested from two sites LB and TB one of which (TB) was on a central North Island New Zealand farm where bovine enzootic haematuria (BEH) was known to occur. The fern was dried, ground and incorporated (25% w/w) into a pelleted diet and fed to female rats for a total of 162 days. Fifteen weeks later when the rats were autopsied it was found that numerous tumours, mainly of the ileum and urinary bladder were present in the animals fed the bracken fern from the TB site.

Pithomyces chartarum spore counts in rumen contents and faeces of sheep exposed to autumn pasture at three different grazing pressures.

Three groups, each of 18 lambs were grazed during autumn in paddocks which had been divided longitudinally by temporary fencing to give twofold differences in grazing intensity between the groups. During the period when spore numbers were elevated the high grazing pressure (HGP) group lost some body weight (-34 g/day). The low grazing pressure (LGP) group gained +90 g/day and the intermediate grazing pressure (IGP) group gained weight slightly (+14 g/day).

Effect of oral doses of zinc oxide on the secretion of pancreatic juice and bile in sheep.

Three sheep were given zinc oxide three times a week for six weeks at a dose rate of 240 mg zinc kg-1. The pancreatic injury resulting from the zinc oxide dosing varied from minor to severe. There was a large reduction in the rate of flow of pancreatic juice and in the concentrations of protein and amylase in the pancreatic juice from the extensively injured pancreas.

The influence of chemical form of zinc on the effects of toxic intraruminal doses of zinc to sheep.

The EDTA, sulphate and oxide compounds of zinc were administered to sheep as a single intraruminal dose (480, 240 or 120 mg Zn per kg body weight) or as thrice-weekly doses (240 mg Zn per kg body weight per dose) for 4 weeks. In the single-dose experiment, serum zinc concentrations rose most rapidly, were highest and fell most rapidly in those animals receiving zinc EDTA. In the sheep receiving the sulphate, serum zinc concentrations were high and stayed high for 2 or 3 days.

Anti-intermediate filament antibody in mice infected with Plasmodium berghei.

Fifteen mice (CBA) were infected with lethal Plasmodium berghei and the development of anti-intermediate filament antibody (anti-IF) studied. Sera from all the infected animals reacted with the cytoplasmic network of intermediate filaments (IF) in the human epidermal laryngeal carcinoma (HEp2) cell line, as demonstrated by indirect immunofluorescence. Sera from 5 control animals injected with 10(4) unparasitized red cells showed no anti-IF reactivity.

Electrophoretic behaviour of blood and synovial fluid lymphocytes in rheumatoid arthritis.

Probit analysis of the electrophoretic mobilities of human blood lymphocytes identifies at least three main subpopulations. According to their rate of movement in an electrical field, the subpopulations are referred to as the fast, intermediate and slow cell distributions. Lymphocytes of the fast and intermediate populations appear to be T cells, while the slow cell population includes cells with B cell characteristics.

The structural requirements for immunoglobulin aggregates to localize in germinal centres.

The capacity of non-heat-aggregated monoclonal human immunoglobulins of different classes, to localize in murine splenic germinal centres within 24 h of intravenous injection has been investigated. It has been shown that at least trimerization of polyclonal IgG must occur before any germinal centre trapping is manifest. Studies of complement fixation by these IgG preparations in vivo, together with studies of the germinal centre trapping of various monoclonal immunoglobulins, have indicated that the sole structural requirement for germinal centre localization of immunoglobulin aggregates is the ability to fix complement.

Reduction of trapping of aggregated human IgG in germinal centers by mitogens.

The effect of nonspecific mitogens on the trapping of 125I-labeled aggregated human IgG (125I-AHGG) in germinal centers (GC) of mouse spleens has been investigated by both radioactivity uptake and immunofluorescence. Phytohemagglutinin and concanavalin A (Con A) significantly decreased trapping. Lipopolysaccharide produced less inhibition, and pokeweed mitogen had no significant effect.

Complement dependence of localisation of aggregated IgG in germinal centres.

In vivo decomplementation of mice with cobra factor completely prevented trapping of aggregated human IgG within splenic germinal centres. Observations of the intrasplenic position of the aggregated material within 8 hr of its injection into normal and decomplemented mice suggest that the early phase of localisation in germinal centres depends on binding to lymphocyte C3 receptors.