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Biomedical subjects

H F Bassett

Publications and source records attributed to H F Bassett.

At least 19 recordsLinked to original sources
PubMed2006

Comparison of fetal and maternal inflammatory responses in the ovine placenta after experimental infection with Chlamydophila abortus.

Placentae from 13 pregnant ewes infected intravenously with Chlamydophila abortus, together with placentae from nine uninfected control ewes, were examined at 14, 21 or 28 days post-inoculation (p.i.). Chlamydial inclusions were present in the trophoblast at 14 days p.i. and were widespread by 21 days p.i. Chorioallantoic lesions (oedema, arteritis and thrombosis) were severe at 28 days p.i., the changes being particularly marked in the membrane surrounding placentomes. Lymphocytes constituted only a small proportion of the cellular infiltrate in the chorioallantois; neutrophil infiltration of the chorionic surface was evident where the trophoblast layer had sloughed, whereas macrophages represented the predominant cell type in the deeper stroma. In contrast, on the maternal side of the placenta, chlamydial inclusions were sparse at all timepoints, and even at 28 days p.i., lesions were restricted to focal endometritis at the placentomal limbus and occasional foci of septal necrosis. T lymphocytes were numerous within endometrial and septal lesions, the infiltrate consistently containing more CD8(+) than CD4(+) cells. The fetal response to chlamydial invasion of the placenta was innate in character, whereas the maternal response appeared to represent an acquired, chlamydia-specific immune response.

Animals↗
PubMed2006

Survey for transmissible spongiform encephalopathies in Irish pigs fed meat and bone meal.

Samples of brain and lymphoid tissues from 1107 meat and bone meal-fed, culled adult pigs from 24 Irish farms were examined for evidence of transmissible spongiform encephalopathy (TSE) by histopathological, immunohistochemical and Western blotting techniques. No evidence of deposits of abnormal prion protein suggesting the presence of TSE was found. Neuropil vacuolation was apparent in the rostral colliculus in 64 per cent of the brains examined and neuronal vacuolation was present in the dorsal vagal nucleus in 15.4 per cent of the brains. However, similar lesions have been described in pigs used as controls in a bovine spongiform encephalopathy challenge experiment. Age-related changes were also observed, including spheroids in the funicular nucleus of 24.5 per cent of the pigs, deposits of lipofuscin in the trigeminal neurons of 13.75 per cent, and mineral deposits in the walls of vessels in the dorsal vagal nucleus of 0.6 per cent. Low-grade non-suppurative inflammatory changes of uncertain origin were observed in 4 per cent of the animals.

Animal Feed↗
PubMed2006

Age-related and non-age-related changes in 100 surveyed horse brains.

Brains from 100 horses, aged 2-25 years, were systematically examined by histopathology at 46 different neuroanatomical sites. The horses were sourced from a slaughterhouse (group A, n = 57), from a kennel that collected dead animals, and from 2 diagnostic laboratories (group B, n = 43). All horses from group A and 26 horses from group B were examined by a veterinarian in the period before death. None of the horses were known to exhibit clinical signs suggestive of neurologic disease. Among the main changes identified were vacuolation in the neuropil (n = 73), neurons (n = 32), white matter (n = 31), and focal perivascular lymphoid cell infiltrates (n = 35). Spheroids were frequently seen (n = 91), and 10 horses each had more than 10 spheroids in the cuneate or gracile nucleus. Statistically significant age-related changes noted included intraneuronal (n = 97) and glial or extracellular lipofuscin deposition (n = 41), hemosiderin deposition around blood vessels (n = 60), and calcium depositions (n = 24). One horse had low-grade nonsuppurative meningoencephalitis; Alzheimer type II cells were detected in the brains of 2 horses. Hyalinized vessel walls in the cerebellum were observed in 1 horse. It was concluded that some histopathologic changes are a frequent feature in equine brains, which has implications for the pathologists involved in equine neurology and disease surveillance.

Aging↗
PubMed2005

Rechallenge of previously-infected pregnant ewes with Chlamydophila abortus.

In an attempt to ascertain the means whereby previous exposure to Chlamydophila (C.) abortus can protect against the re-occurrence of enzootic abortion of ewes (EAE), ten previously-exposed ewes were intravenously rechallenged with a large infective dose of C. abortus during pregnancy. The patterns of development of chlamydial placentitis and its sequelae closely resembled that observed following first-time challenge of previously-naïve ewes, although placentitis appeared to develop more slowly following rechallenge infection and none of the rechallenged ewes aborted. Chorioallantoic and foetal pathology and foetal immune responses were qualitatively similar whilst the local maternal response to C. abortus infection of the endometrium did not appear to differ in rechallenged and first-time challenged sheep. This demonstrates that if C. abortus reaches the foetal side of the placenta, a stereotypical response is elicited, regardless of the status of maternal immunity. Therefore it appears that in natural circumstances, acquired immunity of the dam protects against the re-occurrence of EAE by preventing the causative agent from reaching the susceptible foetal trophoblast.

Abortion, Veterinary↗
PubMed2002

A study of greyhounds with tonsillar enlargement and a history of poor racing performance.

Fifteen greyhounds with tonsillar enlargement were subjected to detailed investigation. Affected greyhounds exhibited coughing, poor racing performance and tonsillar lymphoid hyperplasia over a period of months. Each of the 15 affected animals had evidence of respiratory tract disease. Twelve had non-specific respiratory tract disease, two had pneumonia and one had pulmonary infiltration with eosinophils (PIE). Histopathological examination of the tonsils from affected dogs revealed that greyhounds with tonsillar enlargement are more likely to have tonsillar lymphoid hyperplasia than tonsillitis. As a result, lymphoid hyperplasia would be a suitable term to describe this tonsillar condition. Respiratory tract diseases, rather than tonsillar hyperplasia, was the more likely cause of the poor racing performance of affected dogs. The aetiological relationship, if any, between respiratory disease and tonsillar enlargement is unclear from this study and requires further investigation.

Animals↗
PubMed1998

The distribution of lymphocyte subsets in normal ovine skin.

The distribution of lymphocyte subsets in the skin of clinically normal sheep was studied using monoclonal antibodies to OvCD5, OvCD4, OvCD8, WC1, and CD45RA. Four different anatomical sites were examined in each of 38 sheep. Four different age groups ranging from 7 to 10-day-old lambs to 12 to 14-month-old adults were represented. The majority of lymphocytes in all age groups and at all sites were angiocentrically located within the superficial dermis. Total lymphocyte numbers at each site increased with age. The predominant cell type identified at all sites was WC1+ and the proportion of lymphocytes of this phenotype was significantly higher at wooled sites. Only occasional CD45RA +/- cells were present in any section.

Aging↗
PubMed1996

Effect of dietary restriction on cell-mediated immune responses in cattle infected with Mycobacterium bovis.

Nine M. bovis-infected cattle on a diet deficient in both protein and energy for 133 days lost approximately 17% of their original body weight. However, dietary restriction did not result in any significant reduction in skin sensitivity to PPD, in vitro production of IFN-gamma or lymphocyte blastogenesis. The number of circulating BoCD4+ cells and B cells were similar in both the malnourished and the control cattle. However, significantly lower numbers (P < 0.01) of circulating BoCD2+ cells, BoCD8+ cells, WC1+ gamma delta T cells and ACT2+ cells were found in the malnourished cattle. With the exception of inorganic phosphate, the changes in plasma biochemical parameters were unremarkable.

Animals↗
PubMed1996

A sequential study of the bovine tuberculin reaction.

The sequential histopathological and immunocytochemical changes that characterize the tuberculin reaction were studied in 13 cattle experimentally sensitized to Mycobacterium bovis, and 14 cattle naturally infected with M. bovis. There were two distinct, temporally related patterns of morphological change that were similar for both groups of cattle. The first phase, between 6 hr and 24 hr after the intradermal injection of purified protein derivative (PPD), was characterized by a perivascular aggregation of WC1+ gamma delta T cells and neutrophils and the presence of leucocytoclastic vasculitis within the papillary dermis. The second phase of the reaction was characterized by increased numbers of infiltrating BoCD4+ cells, BoCD8+ cells and macrophages, as well as an increase in expression of the interleukin-2 (IL-2) receptor and the ACT2 antigen. Macrophages were the most numerous infiltrating leucocytes between 24 hr and 72 hr after the intradermal injection of PPD. At 72 hr, the reaction was characterized by intense perivascular cuffing with BoCD4+ cells, BoCD8+ cells and macrophages; gamma delta T cells and neutrophils were a minor component of the reaction and leucocytoclastic vasculitis was no longer observed. No B cells were detected in the dermis throughout the period of study. The increase in skin thickness was primarily because of inflammatory oedema that was contained within the area by a meshwork of fibrin deposited around the collagen bundles of the reticular dermis.

Animals↗
PubMed1995

Effect of a recent injection of purified protein derivative on diagnostic tests for tuberculosis in cattle infected with Mycobacterium bovis.

The intradermal injection of avian and bovine purified protein derivative into 15 Mycobacterium bovis-infected cattle reduced the capacity of a second single intradermal comparative tuberculin test carried out seven days later to predict accurately the animals' infection status (P < 0.001). In vitro lymphyocyte blastogenesis was also reduced (P < 0.05) but the in vitro production of interferon-gamma was unaffected.

Animals↗
PubMed1995

Effects of dexamethasone on cell-mediated immune responses in cattle sensitized to Mycobacterium bovis.

Systemic administration of dexamethasone led to a significant reduction in the size of the tuberculin reaction in response to intradermal injection of bovine purified protein derivative in 18 cattle experimentally sensitized to Mycobacterium bovis (P < 0.01) and 8 cattle naturally infected with M bovis (P < 0.001). The reaction in 6 of the 7 M bovis infected cattle that received dexamethasone was classified as negative for the standard interpretation of the single intradermal comparative tuberculin test. Significantly fewer BoCD2+ (P < 0.05) and BoCD4+ T cells (P < 0.001) were present at the reaction site and in blood of dexamethasone-treated cattle, compared with untreated control cattle. Significantly fewer cells expressing the interleukin-2 receptor and WC1+ gamma delta T cells (P < 0.001), and a significantly greater number of cells expressing the ACT2 antigen (P < 0.05) were found at the reaction site in dexamethasone treated cattle than in controls. The number of BoCD8+ T cells at the reaction site and in blood was not significantly affected by administration of dexamethasone. In vitro production of interferon-gamma by lymphocytes incubated with bovine purified protein derivative also was significantly lower (P < 0.01) in the dexamethasone treated cattle.

Animals↗