Biomedical subjects
Publications and source records attributed to T L Rothwell.
In order to localize protective antigens in Trichostrongylus colubriformis, adult worms were microdissected and the capacity of worm tissues to protect guinea pigs against infection examined. The results suggest that T. colubriformis protective antigens are widely distributed in the body and are not concentrated in the intestine or glandular structures.
The cultivation of bone marrow was used to quantitate the levels of eosinophil differentiation factors (EDF) produced in conditioned medium (CM) by incubation of mesenteric lymph node cells (MLNC) with mitogens or specific antigens from the intestinal nematode parasite, Trichostrongylus colubriformis. In liquid cultures with 20 units ml-1 recombinant murine interleukin-5 (IL-5), bone marrow cells (BMC) from either normal or infected donors contained less than 5% eosinophils and differentiated to greater than 50% eosinophils over 2-3 weeks. Conditioned medium from 3-4 week infected donors produced between 20 and 50% eosinophils when donor MLNC were stimulated with the specific antigen preparation SP3, but macrophages predominated when using CM from MLNC incubated with Concanavalin A (ConA). CM from MLNC of challenged donors incubated with SP3 produced 30-70% eosinophils in BMC assays, with highest levels induced by CM from high responder (HR) donors. Marrow from parasitized or normal donors gave rise to comparable proportions of eosinophils. CM was also produced from LNC of donors given protein or parasite antigens in adjuvant where between 28 and 35% eosinophils were produced in culture. There were no differences between activities attributable to the antigen, but Freund's complete adjuvant induced earlier differentiation of BMC than alum-induced CM. The results confirm that high levels of EDF activity are specifically induced by parasitic infection, and can also be produced by intraperitoneal and subcutaneous inoculation of adjuvanted antigens. Consistent with the greater eosinophilia exhibited by HR guinea pigs to infection with T.colubriformis L3, their MLNC also produced the highest levels of EDF activity.
Research in laboratory animals suggests that eosinophil numbers in some cutaneous reactions may reveal inherent differences in resistance to parasite infection. An intradermal injection with 10 microgram of the mitogen phytohaemagglutinin, followed by counting eosinophils in the deep dermis of skin biopsies removed 24 hours later, appears to be a practical and reproducible way of comparing the ability of individual sheep to marshal eosinophils in a tissue. This procedure will allow study of the relationship between eosinophil response and resistance to parasite infection in sheep.
Outbred guinea pigs became infected with the mite Trixacarus caviae (Acarina, Sarcoptidae) when introduced into an infected colony. Mite numbers were highest after one month, then fell progressively. Infected guinea pigs developed a neutrophilia, monocytosis, eosinophilia and basophilia. Despite pronounced reactive changes in the superficial lymph nodes, infected guinea pigs developed only a mild dermatitis. In contrast, home bred animals, susceptible to T. caviae acquired many mites and developed a severe chronic dermatitis. Trixacaral manage in guinea pigs offers considerable potential for the study of mite infections in man and animals.
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Trichostrongylus colubriformis infective larvae were subjected to various levels of gamma-irradiation and administered to guinea pigs. The worms surviving were subsequently counted. Irradiation with 12.9 C kg-1 inhibited worm establishment but lower doses neither influenced worm establishment nor survival.
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Approximately 40% of exsheathed Haemonchus contortus larvae administered to guinea pigs established in the stomach and developed into fourth stage larvae. Most worms were then lost between 5 and 7 days after infection and the guinea pigs were resistant to a second infection. Haemorrhage, oedema and infiltration with inflammatory cells, especially eosinophils, developed in the stomach wall of infected guinea pigs and reactive hyperplastic changes occurred in the gastric lymph node. H. contortus infection of guinea pigs has some potential as a model for study of the pathology, immunology and chemotherapy of gastric nematodiasis.
Guinea pigs with genetically determined resistance or susceptibility to infection with the nematode parasite Trichostrongylus colubriformis were allowed to become infected with the sarcoptid mite Trixacarus caviae. Compared with nematode-susceptible guinea pigs, nematode-resistant animals had larger populations of mites and developed a more severe dermatitis, with greater mast cell hyperplasia and many more infiltrating eosinophils. The results suggest that animals bred for resistance to one parasite may have greater susceptibility to other parasites.
A siliceous pneumoconiosis was detected in two dogs by light microscopical, transmission electron microscopical and elemental analysis methods. Aluminium and silicon were the predominant elements and were present in macrophages associated with airways and vessels. The significance and origin of the deposits are discussed.
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In a survey of dogs in Sydney, mastocytomas (16.1%) and histiocytomas (14.0%) were the most common in a total of 1,000 skin neoplasms. The basal cell and appendage group provided 25.5% of the neoplasms. The prevalence of the various neoplasms, the age of affected dogs, the proportion in the sexes, the common sites of occurrence and prevalence in the different breeds were broadly similar to findings in surveys in other countries, except that in the Syndeny dogs there was a greater prevalence of histiocytomas and haemangiopericytomas, a more common occurrence of histiocytomas in mature dogs, an occurrence of histiocytomas in similar numbers on the head, trunk and limbs, and a remarkably common development of squamous cell carcinomas in Dalmatians.
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A four-year-old castrated male domestic shorthair cat with recent onset of lethargy and depression was found to have hypokalaemia, low plasma bicarbonate concentration and a urine pH of 7. Subsequent findings of hyperchloraemic metabolic acidosis with failure to produce acid urine led to a diagnosis of distal renal tubular acidosis. Pyelonephritis associated with Escherichia coli infection of the urinary tract was also diagnosed. The urinary tract infection was eliminated by antibiotic treatment. For two years subsequently, the clinical effects of distal renal tubular acidosis have been controlled by oral administration of potassium bicarbonate, although some biochemical abnormalities have persisted.
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