Biomedical subjects
Publications and source records attributed to R W Cook.
Hens were exposed to small-particle aerosols containing different concentrations of Salmonella enteritidis phage type 4. They developed a systemic infection and some birds were still excreting the organism in the faeces when killed 28 days after infection. S enteritidis was present for a similar period in a wide range of alimentary tract issues and in the ovary and oviduct.
Interstitial pneumonia unrelated to Pneumocystis carinii or other infections was observed histopathologically in 5 of 25 rhesus monkeys infected with simian immunodeficiency virus (SIV). The predominant lesion was lymphocytic infiltration of interalveolar septa and hyperplasia of peribronchial and perivascular lymphoid tissue. Immunohistochemical staining using a panel of antibodies against human T and B lymphocytes, macrophages, and immunoglobulins showed that peribronchial aggregates and interstitial infiltrates were predominantly B cells, whereas perivascular masses consisted mainly of T cells. One animal with a primary B-cell lymphoma of the spinal cord had secondary plasmacytoid lymphomatous nodules throughout the lung which were accompanied locally by reactive B-cell lymphoid follicles. Another animal also had large areas of diffuse alveolar fibrosis and epithelial metaplasia to a bronchiolar type. In two monkeys, branches of the pulmonary arteries showed intimal proliferation and organizing occlusive thrombi, some of which were mineralized.
The pathological changes associated with ageing and simian immunodeficiency virus (SIV) infection in groups of immature, adult and ageing Rhesus monkeys were studied. Eighty three per cent (5 of 6) of uninfected ageing animals had hyperplasia of the prostate, 33 per cent (2 of 6) had mild prostatitis and in 66 per cent (4 of 6) there were calcified concretions in the seminal vesicles. The testes were normal and showed active spermatogenesis. In the SIV-infected animals, two types of lesion occurred; the most common, in 81 per cent (18 of 22 monkeys), was the presence of focal lymphoid infiltrations in the epididymis, prostate or seminal vesicles. The other was hypospermatogenesis (23 per cent, 4 of 17) with degeneration of seminiferous tubules. Immunocytochemical staining demonstrated that the lymphoid masses contained approximately equal numbers of B and T lymphocytes, but the majority of diffusely scattered cells were T lymphocytes. Staining for SIV antigen identified small numbers of positive lymphocytes and macrophages in all tissues.
Pneumocystis carinii pneumonia occurred in 6 of 17 rhesus monkeys infected with simian immunodeficiency virus and was studied by immunohistochemistry and by scanning and transmission electron microscopy. A monoclonal antibody/streptavidin-biotin-peroxidase staining method was highly sensitive for detecting the organisms in small, early lesions and was much more sensitive and specific than traditional silver impregnation methods. Reprocessing of paraffin wax-embedded lung tissue for scanning electron microscopy and use of a video printer to produce a photographic montage of light microscopic lesions allowed the same areas of tissue to be examined and compared by both methods. The ultrastructural morphology of P. carinii in the rhesus monkey was identical to that in man, as were the histological and electron microscopic lesions, including pulmonary fibrosis. Trophozoites were seen attached to alveolar type I epithelium mainly by intimate apposition to the plasma membrane, but scanning electron microscopy also showed attachment by elongated filopodia. Few macrophages were present in infected alveoli, and though phagocytosis followed by digestion of P. carinii trophozoites was observed, it appeared to occur at a very low level.
Two Rhesus monkeys infected with simian immunodeficiency virus for 15 and 24 months developed generalized oedema and one became jaundiced. At necropsy, the liver and pancreas were hard and irregular and the gall bladder was thickened. Histopathological examination showed extensive fibrosis of the pancreas, loss of exocrine acini and marked proliferation of ductules. Numerous cryptosporidia were present on the duct epithelium. The liver of both animals had widespread cirrhosis, bile duct proliferation and cholangitis. Cryptosporidia were found in many bile ducts and on the hyperplastic gall bladder epithelium. Lymph nodes and spleen of both animals showed depletion of cortical and paracortical elements characteristic of advanced immunodeficiency virus infection.
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The histological lesions were studied in seven rhesus and three cynomolgus monkeys infected with simian immunodeficiency virus for periods ranging from nine weeks to 18 months. Lymphoreticular changes included hyperplasia, follicular involution and depletion, and one animal had amyloidosis of the spleen. Hyperplastic changes also took place in mucosa-associated lymphoid tissue and infiltrations occurred in the vaginal mucosa of one animal, which could be significant in sexual transmission of the infection. The range of opportunistic infections was small compared with that in human AIDS patients, although two monkeys had Pneumocystis carinii pneumonia. Enterocolitis was a common finding and brown adipose tissue was transformed into a large vacuolated type. Lesions of the central nervous system were found in five of nine monkeys, and consisted of foci of glial activity and perivascular and meningeal lymphocytic infiltration. A lymphoma involving the lumbar spinal cord developed in one animal.
Streptococcus suis was recovered from 9 outbreaks of septicaemia and meningitis in weaned pigs between 1979 and 1983. Fifteen isolates from 7 outbreaks were identified as S. suis type 9, and 3 isolates from 2 outbreaks as S. suis type 2. Three further isolates of S. suis type 2 and an isolate of S. suis type 3 were recovered from cases of bronchopneumonia in weaned pigs from 4 other piggeries.
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Electrocardiograms were recorded from 4 calves with cardiomyopathy and woolly haircoat syndrome (CWH), a lethal autosomal recessive trait of Poll Hereford cattle and from 9 unaffected calves. Electrocardiograms of calves with CWH were characterised by multifocal ventricular premature contractions which occurred singly, in pairs, in runs and as episodes of ventricular tachycardia. Bigeminal rhythms were recorded occasionally. The frequency of ventricular premature contractions ranged from 5 to 120.min-1. Ventricular premature contractions in calves with CWH were attributed to myocardial degeneration and fibrosis which were observed grossly and microscopically. Electrocardiograms in unaffected calves were characterised by normal sinus rhythm and by variation in the morphology of wave forms between animals. The durations of the various wave forms were less than those previously recorded from adult cattle.
A syndrome in cattle of diarrhoea and death associated with enteric Yersinia pseudotuberculosis infection is described. Outbreaks occurred during winter and early spring in adult cattle grazing pastures waterlogged by recent flooding or persistent heavy rain. Antibiotic therapy was effective early in the course of the syndrome. At necropsy there was severe acute enterocolitis, and bacteria consistent with Y. pseudotuberculosis were observed in the lesions. This organism could usually be isolated from the intestines of affected animals but was recovered less often from other organs. Representative isolates were identified as Y. pseudotuberculosis serotype III. The association of this syndrome with waterlogged pastures and low temperatures suggests that these conditions favour transmission of Y. pseudotuberculosis infection in cattle. The role of Y. pseudotuberculosis as primary pathogen requires confirmation.
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A method was devised for surgical removal of the pyloric antrum in 3-week-old rats. Contrary to published experiences with older rats, it was found that ligation of right and left gastroepiploic arteries was not necessary in young animals. Erythrocytes and fluids were routinely administered postoperatively, and recovered animals were denied access to water and food for 2 and 3 days, respectively. When the rats were fasted overnight prior to surgery, the recovery rate was 87% (27 of 31 attempted). Surgical sites were intact and showed minimal adhesions 2 months later. When overnight fasting was omitted, only 57% survived (8 of 14 attempted), because extensive manipulations were necessary to remove gastric contents, and this often produced shock.
A 10-month-old female, Wire-haired Pointing Griffon dog had a hamartoma of the hypothalamus. Episodes of sudden flaccid collapse had increased in frequency and duration for 7 months. Cerebrospinal fluid pressure was normal. A flat, pedunculated mass, 2.5 X 3.0 X 0.9 cm, covered the brain stem between the pituitary gland and pons. Its 1.2-cm-diameter connection to the hypothalamus obliterated the mammillary bodies and extended to the tuber cinereum, distorting the hypothalamus and displacing the third ventricle which also divided the rostral part of the mass. The tissue of the hamartoma resembled gray matter with bullous cytoplasmic vacuolation of many neurons, spongiform change, gemistocytosis and microscopic foci of calcification.
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Dermatophilosis was diagnosed in 2 of 13 captive polar bears (Thalarctos maritimus), causing generalized dermatitis of 3 years' and 6 months' duration, respectively. Progressive clinical signs included yellowing and darkening of the hair, pruritus, encrustation of skin, and reluctance to bathe. Dramatic resolution of lesions occurred during 8 weeks of twice-weekly intramuscular treatment with long-acting penicillin.
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