Sionagh Smith

Stigmatization of AIDS patients by physicians.

A randomly selected sample of physicians in three large cities was asked to read one of four vignettes describing a patient. They then completed a set of objective attitude measures eliciting their reactions to the patient described in the vignette. The vignettes were identical except that the patients illness was identified as either acquired immunodeficiency syndrome (AIDS) or leukemia and the patients sexual preference as either heterosexual or homosexual. Harsh attitude judgements were associated with the AIDS portrayals, as well as much less willingness to interact even in routine conversation when the patients illness was identified as AIDS. Increasing numbers of AIDS patients will be seeking medical attention from physicians in all areas of the country and it will be important for health care professions to develop programs which counter unreasonable stigma and prejudicial attitudes that may be associated with this illness.

A Comparative Review of Melanocytic Neoplasms

Melanoma is a devastating disease frequently encountered within both veterinary and human medicine. Molecular changes linked with neoplastic transformation of melanocytes include mutations in genes that encode proteins intrinsic to the regulatory pathways of two tumor suppressor proteins (retinoblastoma protein and p53), proto-oncogene mutation to oncogenes, altered expression of epithelial cadherin and CD44 adhesion molecules, and upregulation of angiogenic factors and other growth factors. Histologic evaluation of the primary mass is the most common means of diagnosis, with cytology used more frequently to document metastasis. Melanomas highly variable histologic and cytologic patterns can make diagnosis by either method problematic. Adherent epithelioid morphology, including signet ring forms, and nonadherent round and spindle forms are recognized, with pigmentation an inconsistent finding. The site of the tumor, the thickness of the primary tumor or depth of invasion, and the number of mitotic figures per high-power field or per millimeter are used histologically to predict biologic behavior, whereas site and degree of pleomorphism are typically used for cytologic preparations. Diagnosis of amelanotic melanoma can be aided by ancillary diagnostic techniques. Tumor cells are usually positive for vimentin, S100, neuron-specific enolase, and Melan-A, and negative for cytokeratin. Melan-A as a positive marker is not as sensitive as the others are but is likely more specific. Monoclonal antibodies to human melanosome-specific antigens 1 and 5 cross-react with canine antigens for a combined sensitivity rate of 83%. Mouse monoclonal antibody IBF9 specifically recognizes canine melanoma antigen and also has good sensitivity. Serologic markers, including cytokines, cell adhesion molecules, and melanoma-inhibitory activity, are being investigated as potential sentinels of melanoma. Currently, there is no single diagnostic technique capable of differentiating benign from malignant melanocytic neoplasms or predicting survival time.

Medical Students' Attitudes toward AIDS and Homosexual Patients.

More than most diseases, acquired immune deficiency syndrome (AIDS) appears to elicit highly negative, fearful, and prejudicial attitudes. In the study reported here, medical students read one of four patient vignettes. The vignettes were identical in content except that the patient was identified as having either AIDS or leukemia as either homosexual or heterosexual. The students then completed a set of objective measures that assessed their attitudes toward the patient portrayed in the vignette. Multivariate and univariate analyses of variance of their responses revealed that the students held negative and prejudiced attitudes toward both the AIDS and homosexual patients. This finding suggests that medical educators should recognize that many students have stigmatizing, negative attitudes toward homosexuals and patients with AIDS. These educators should promote greater sensitivity, knowledge, and understanding among medical students of those at risk for AIDS and AIDS patients.

Disposal and disease rates in 340 British dairy herds

Data derived from 340 dairy herds, mainly in southern England, between April 1998 and March 1999, showed that the average total culling rate was 22.1 per cent, with 5.6 per cent for infertility, 3.6 per cent for mastitis, 1.7 per cent for lameness, 2.0 per cent for poor milk yield, 3.7 per cent for age and 5.5 per cent for miscellaneous reasons which included death. The average annual rate of assisted calvings was 8.7 per cent, of injury 0.9 per cent, digestive disease 1.3 per cent, ketosis 0.4 per cent, hypomagnesaemia 0.7 per cent, hypocalcaemia 5.3 per cent, mastitis 36.6 per cent, and lameness 23.7 per cent. There was a significant association (P<0.001) between higher rates of mastitis in cows housed in straw yards as opposed to cubicles and also between higher rates of lameness in cows housed in cubicles as opposed to yards (P<0.015). However, there were farms with low rates of mastitis in cows kept in straw yards and low rates of lameness in cows kept in cubicles. Larger herds tended to have more problems with lameness and higher bulk milk somatic cell counts (BMscc). There was a positive association between BMScc and mastitis rate.

Development of persistent intestinal infection and excretion of Lawsonia intracellularis by piglets

Challenge experiments using Lawsonia intracellularis as oral inocula have established its aetiological role in porcine proliferative enteropathy. Thirty piglets, in four groups, were weaned at 21 days of age and inoculated orally at 24 days. Six piglets were challenged with 1.0 x 10(8) L intracellularis strain 916/91 (NCTC 12657) passaged 12 times in vitro, six with 5.0 x 10(8) of the same strain, seven with 3.0 x 10(8) L intracellularis strain LR 189/5/83, passaged nine times, and 11 controls were dosed with sucrose-potassium glutamate buffer. An immunofluorescence assay for L intracellularis was applied to faecal smears and a polymerase chain reaction (PCR) incorporating L intracellularis-specific primers was applied to extracts of bacterial DNA derived from the faeces samples. Up to five pigs in each challenge group excreted detectable L intracellularis in faeces, in samples taken between two and 10 weeks after challenge. Some of the pigs had up to 7 x 10(8) L intracellularis g-1 faeces. The average weight gains of the higher dose challenge groups were moderately below those of the control pigs between three and nine weeks after challenge; diarrhoea was also observed in six pigs, two to four weeks after challenge. Numerous L intracellularis were detected in the intestines of all the pigs challenged with strain LR 189/5/83 and two of the pigs challenged with 916/91, but not in other tissues.

A role for solvents in the toxicity of agricultural organophosphorus pesticides

Organophosphorus (OP) insecticide self-poisoning is responsible for about one-quarter of global suicides. Treatment focuses on the fact that OP compounds inhibit acetylcholinesterase (AChE); however, AChE-reactivating drugs do not benefit poisoned humans. We therefore studied the role of solvent coformulants in OP toxicity in a novel minipig model of agricultural OP poisoning. Gottingen minipigs were orally poisoned with clinically relevant doses of agricultural emulsifiable concentrate (EC) dimethoate, dimethoate active ingredient (AI) alone, or solvents. Cardiorespiratory physiology and neuromuscular (NMJ) function, blood AChE activity, and arterial lactate concentration were monitored for 12 h to assess poisoning severity. Poisoning with agricultural dimethoate EC40, but not saline, caused respiratory arrest within 30 min, severe distributive shock and NMJ dysfunction, that was similar to human poisoning. Mean arterial lactate rose to 15.6 [SD 2.8] mM in poisoned pigs compared to 1.4 [0.4] in controls. Moderate toxicity resulted from poisoning with dimethoate AI alone, or the major solvent cyclohexanone. Combining dimethoate with cyclohexanone reproduced severe poisoning characteristic of agricultural dimethoate EC poisoning. A formulation without cyclohexanone showed less mammalian toxicity. These results indicate that solvents play a crucial role in dimethoate toxicity. Regulatory assessment of pesticide toxicity should include solvents as well as the AIs which currently dominate the assessment. Reformulation of OP insecticides to ensure that the agricultural product has lower mammalian toxicity could result in fewer deaths after suicidal ingestion and rapidly reduce global suicide rates.

Treatment and prevention of porcine proliferative enteropathy with oral tiamulin

The effect of an oral treatment or prevention programme, incorporating the antibiotic tiamulin, on the development of proliferative enteropathy in experimentally challenged pigs was studied. Twenty weaner pigs were challenged orally with a virulent inoculum of Lawsonia intracellularis strain LR189/5/83, a British isolate of the causative agent of porcine proliferative enteropathy, and seven control pigs were dosed with a buffer solution. Seven of the 20 challenged pigs were left untreated; they gained less weight than the controls and three of them developed mild to moderate diarrhoea two weeks after the challenge. All seven developed lesions, six visible grossly, of proliferative enteropathy, and numerous intracellular L intracellularis were detected in sections of the intestines examined three weeks after the challenge. To test a ‘prevention’ dosing strategy for tiamulin, six of the challenged pigs were dosed orally with 50 ppm tiamulin, incorporated in a 2 per cent stabilised premix, given from two days before the challenge until they were euthanased. To test a ‘treatment’ strategy, the remaining group of seven challenged pigs were dosed orally with 150 ppm tiamulin given in the premix from seven days after challenge until they were euthanased. All the control pigs and the 13 pigs treated with tiamulin, either before or after challenge, remained clinically normal and had no specific lesions of proliferative enteropathy in sections of the intestines examined post mortem.

Tumors affecting the spinal cord of cats: 85 cases (1980-2005).

OBJECTIVE To determine the prevalence of lymphosarcoma and other tumors affecting the spinal cord of cats and to relate specific types of tumors with signalment, history, and clinical findings. DESIGN Retrospective case series. ANIMALS 85 cats with tumors affecting the spinal cord. PROCEDURES Medical records of cats with histologically confirmed primary or metastatic tumors of the spinal cord or tumors causing spinal cord disease by local extension from adjacent tissues examined between 1980 and 2005 were reviewed. Data on signalment; clinical history; results of neurologic examination, diagnostic imaging, and clinical pathologic evaluation; and location of tumor within the spinal cord were obtained from medical records and analyzed by use of logistic regression models. RESULTS Lymphosarcoma was the most common tumor and affected the spinal cord in 33 (38.8%) cats, followed by osteosarcoma in 14 (16.5%) cats. Cats with lymphosarcoma were typically younger at initial examination, had a shorter duration of clinical signs, and had lesions in more regions of the CNS than did cats with other types of tumors. In 22 of 26 (84.6%) cats with lymphosarcoma, the tumor was also found in extraneural sites. CONCLUSIONS AND CLINICAL RELEVANCE Data for spinal cord tumors in this population of cats were analyzed by logistic regression analysis, which effectively distinguished cats with lymphosarcoma from cats with other types of tumors. Additional clinical information reported here will help to increase the index of suspicion or definitive antemortem diagnosis of spinal cord tumors of cats.

Cerebral Vascular Hamartomas in Five Dogs

Vascular hamartomas are considered developmental lesions rather than true neoplasms. Reports of such anomalies in the canine brain are scarce, and their classification is confusing. This case series of vascular hamartomas from the brains of five dogs was characterized using histochemistry and immunohistochemistry, in addition to gross and microscopic findings. All five hamartomas were located in the telencephalon, three in the pyriform lobe, without any predilection for the left or right side. Each hamartoma consisted of a proliferation of thin-walled vessels which varied in caliber. These vessels were elastin-negative, with varying amounts of collagen and no muscular component. In four of the five hamartomas, lining cells were actin- and factor VIII-positive. All five hamartomas contained glial fibrillary acid protein (GFAP)-positive parenchyma at moderate to high frequency, and four contained neurofilament-positive axons between component vessels. This report shows that vascular hamartomas in the canine brain are structural malformations for which immunohistochemistry is useful for accurate classification.

Questionnaire survey of proliferative enteropathy on British pig farms

Risk factors for proliferative enteropathy were investigated by means of a postal questionnaire survey of randomly selected British pig farms. Replies were received from 319 (56 per cent) of the 569 questionnaires posted, representing 1.5 per cent of the total number of pig farms in Britain. Thirty-one per cent of the farms had experienced at least one episode of proliferative enteropathy within the previous three years, usually confirmed by their veterinary surgeon. There was a strong association for the occurrence of proliferative enteropathy in herds of over 500 sows (P<0.005) and in herds with enzootic pneumonia (P<0.01). Outbreaks had occurred in five of the six nucleus herds surveyed, the other had only 80 sows. Outbreaks occurred in 32 of 69 herds that had obtained their replacement boars from nucleus herds (P<0.05), suggesting that infected boars may carry the disease into distant herds. The use of either fully slatted (P<0.05) or fully meshed floors (P<0.01) above sunken pits in buildings used to house pigs immediately after weaning, and the use of partially (P<0.05) or fully slatted floors (P<0.05) in buildings used to house pigs two to six months old, were risk factors for outbreaks of proliferative enteropathy, compared with the use of straw bedding or solid floors. The destocking of entire buildings containing pigs two to four months old before the introduction of fresh pigs, was associated with a reduced risk (P<0.05), but the destocking of selected pens rather than the whole building had no such association. The type of diet, or feeding or watering system and the types of buildings used were not identified as risk factors.