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Biomedical subjects

W G Halliday

Publications and source records attributed to W G Halliday.

12 recordsLinked to original sources
PubMed1992

Infection specific prion protein (PrP) accumulates on neuronal plasmalemma in scrapie infected mice.

Prion protein (PrP) is an abundant membrane-associated host protein which accumulates in abnormal, relatively protease-resistant forms in the brains of animals with scrapie and related diseases. Using correlative light and electron microscopy we determined the sites of subcellular localisation of PrP in mice infected with the 87V strain of scrapie. Disease specific accumulation of PrP was observed at light microscopy as amyloid plaques or as diffuse or granular staining within the neuropil, often clearly associated with individual neurons. Serial electron microscopical preparations were immunostained for PrP by the immunogold method. Gold particles were located on amyloid fibrils and on the plasmalemma of neurites at the periphery of plaques and in the neuropil, irrespective of the morphological form of PrP accumulation when viewed by light microscopy. This suggests that amyloid fibrils are formed following the accumulation and aggregation of sub-unit proteins at the plasmalemma and, furthermore, that normal PrP may be converted to its pathological form at this site.

Amyloid↗
PubMed1992

A morphometric and immunohistochemical study of the vestibular nuclear complex in bovine spongiform encephalopathy.

A morphometric and immunohistochemical study of the vestibular nuclear complex was performed on five bovine spongiform encephalopathy (BSE) and five control cow brains. Neurons of the lateral and superior vestibular nuclei were counted at 500-microns intervals in 10-microns-thick sections, using an image analysis system comprising a projection microscope and digitising pad linked to a computer. A bimodal distribution of neuron diameters was recognised in the brains of normal cattle. One population of neurons had a mean diameter of 30 microns and the other had a mean diameter of 60 microns. The vestibular nuclei from BSE cattle had an approximately 50% reduction in total numbers of neurons when compared with controls (P < 0.01). Cattle which were clinically diseased longer had the fewest number of neurons preserved. Diminished numbers of neurons were detected throughout the area studied and affected neurons of all diameters. Immunohistochemical staining for synaptophysin, a protein present in synapses throughout the CNS, showed no significant reduction in axon terminals synapsing with vestibular neurons, including vacuolated neurons of BSE brains, when controls and BSE brains were compared. This suggests that de-afferentation of neurons is not the cause of neuronal loss. Prion protein was detected in the neuropil of the vestibular nuclear complex of BSE brains but not control brains. These studies show that previously unsuspected neuronal loss is a significant feature of BSE.

Animals↗
PubMed1979

Investigations of 'transfer factor' activity in the transfer of immunity to Trichostrongylus axei infections in sheep.

Three investigations are described in which non-dialysed and dialysed leucocyte lysates, 'transfer factor' prepared from the blood of sheep infected with Trichostrongylus axei successfully transferred immunity to challenge infection with that parasite in susceptible lambs. Similar leucocyte lysates from parasite-free lambs failed to transfer a similar resistance to challenge infection. 'Transfer factor' treatment produced a 30--72 per cent reduction in a total worm burden compared to susceptible control lambs. In the first two investigations the donor and recipient lambs were genetically dissimilar and in the third investigation were of different breeds. The resistance transfer was considered to operate independently of immune incompetence.

Animals↗
PubMed1979

Investigation of Haemonchus contortus infections in sheep. Comparison of irradiated larvae and transfer factor treatment.

A comparison is made between the resistance conferred to Haemonchus contortus challenge by irradiated larval treatment and transfer factor (TF) treatment in four-month-old lambs and seven-month-old lambs. As in previous investigations the irradiated larval treatment failed to confer resistance to the four-month-old lambs challenged with 10,000 third stage larvae while similar irradiated larval treatment in seven-month-old lambs reduced the worm burdens by 40 per cent compared to controls. The TF treatment produced a 34 per cent reduction in the challenge infection in the four-month-old lambs and a 45 per cent reduction in the seven-month-old lambs compared to the control lambs. It is concluded that TF activity operates independently of immune competence.

Animals↗
PubMed1978

Haematological and blood chemistry "comparison values" for clinical pathology in poultry.

Twelve blood chemistry values, six haematological values and bodyweight were estimated for six-week-old specific-pathogen-free brown leghorns. Observations were based on 208 birds sampled from 11 groups. Subsequently the same values were estimated for specific pathogen free brown leghorns and broiler hybrids of differing ages. These estimates have been designated "comparison values" and were intended for reference use in clinical pathology. Results were compared with 14 "comparison value" estimated obtained previously for six-week-old commercial broiler hybrids. Haematological values varied with age and type of bird. Differences were observed between bird types in serum protein, serum cholesterol, uric acid, calcium and potassium levels and in weight. The significance of these differences is discussed.

Age Factors↗
PubMed1977

Effect of transportation on blood metabolites in broilers.

1. Groups of 30 broilers from seven flocks were bled and weighed at the farm and a further sample of 10 broilers from each flock was transported from 8 to 16 km to the laboratory prior to bleeding and weighing. 2. One haematological and 11 biochemical analyses were made on each blood sample. 3. Although transportation did lead to significant differences in certain variables, the trends were consistent and sampling following transit is considered acceptable for clinical pathology studies.

Animals↗