Paul J. Canfield

TOPICAL UROCANIC ACID ENHANCES UV‐INDUCED TUMOUR YIELD AND MALIGNANCY IN THE HAIRLESS MOUSE

Abstract— Epidermal urocanic acid has been postulated to be the mediator of the specific state of immunosuppression induced by UV irradiation, by which UV‐initiated tumour cells are able to evade normal recognition and can survive to grow progressively into malignant tumours. These experiments demonstrate that topical application of UV‐irradiated urocanic acid systemically suppresses the contact type hypersensitivity response to oxazolone in hairless mice. In addition, topically applied urocanic acid markedly increases the overt tumour yield and the degree of malignancy in hairless mice exposed chronically to daily minimally erythema] doses of simulated solar UV light. Topical urocanic acid also increases the number of latent UV‐initiated tumours, detectable by croton oil promotion. Therefore UV photoproducts of urocanic acid can both systemically suppress contact hypersensitivitv in the epidermis, and also enhance early survival of UV‐initiated tumour cells resulting in augmentation of UV photocarcinogenesis.

Cryptococcus neoformans var. gattii in the koala (Phascolarctos cinereus): a review of 43 cases of cryptococcosis.

Details of 11 previously reported cases and 32 new cases of cryptococcosis in captive and wild koalas were analysed. Cryptococcus neoformans var. gattii accounted for all 29 cases in which varietal status was determined. No age or sex predisposition was observed. The respiratory tract was the primary focus of disease in 77% of cases. Although the lower respiratory tract was affected most commonly (60% of cases), 30% of cases had upper respiratory tract lesions and 14% had both. Dissemination was common, especially to the central nervous system (37% cases). Local extension to surrounding tissues was a feature of upper respiratory tract disease. Other tissues showing cryptococcal invasion included lymph nodes (19%), gastrointestinal tract (12%), kidneys (12%), spleen (9%) and skin (7%). Only three cases (7%) had no respiratory tract or central nervous system involvement, two cases of primary skin inoculation and one case of primary lymphadenopathy. Late presentation was a likely factor in the high proportion of cases with disseminated disease (40%). The proportion of koala cases with involvement of the central nervous system, lower respiratory tract and skin, parallels what has been reported for immunocompetent people. Cryptococcosis in the koala appears to be an excellent naturally occurring model for examination of the cryptococcal host-parasite relationship in all species.

Low-Grade Alimentary Lymphoma: Clinicopathological Findings and Response to Treatment in 17 Cases:

Low-grade alimentary lymphoma (LGAL) was diagnosed by histological and immunohistochemical evaluation of full-thickness biopsies from multiple regions of the gastrointestinal tract collected during exploratory laparotomy in 17 cats. The most common clinical signs were weight loss (n=17) and vomiting and/or diarrhoea (n=15). Clinical signs were chronic in 11 cases. Abdominal palpation was abnormal in 12 cats, including diffuse intestinal thickening (n=8), an abdominal mass due to mesenteric lymph node enlargement (n=5) and a focal mural intestinal mass (n=1). The most common ultrasonographic finding was normal or increased intestinal wall thickness with preservation of layering. Ultrasound-guided fine-needle aspirates of mesenteric lymph nodes (n=9) were incorrectly identified as benign lymphoid hyperplasia in eight cats, in which the histological diagnosis from biopsies was lymphoma. There was neoplastic infiltration of more than one anatomic region of the gastrointestinal tract in 16/17 cats. The jejunum (15/15 cats) and ileum (13/14 cats), followed by the duodenum (10/12 cats), were the most frequently affected sites. Twelve cats were treated with oral prednisolone and high-dose pulse chlorambucil, two with a modified Madison–Wisconsin multiagent protocol and three with a combination of both protocols. Thirteen of the 17 cats (76%) had complete clinical remission with a median remission time of 18.9 months. Cats that achieved complete remission had significantly longer median survival times (19.3 months) than cats that did not achieve complete remission (n=4) (4.1 months; P=0.019). The prognosis for cats with LGAL treated with oral prednisolone in combination with high-dose pulse chlorambucil is good to excellent.

Immunohistological staining of lymphoid tissue in four Australian marsupial species using species cross-reactive antibodies

Antibodies raised against evolutionarily conserved intracytoplasmic peptide sequences of human T and B lymphocyte antigens and an antibody raised specifically against koala serum IgG were assessed for their capacity for immunoperoxidase staining of formalin fixed lymphoid tissues of koalas (Phascolarctos cinereus), common brushtail possums (Trichosurus vulpecula), common ringtail possums (Pseudocheirus peregrinus) and tammar wallabies (Macropus eugenii). Utilizing microwave pretreatment and a streptavidin biotin‐horseradish peroxidase method for histochemical staining, polyclonal anti‐human CD3 (for T cells), monoclonal anti‐human CD5 (for T cells), monoclonal anti‐human CD79b cy (for B cells) and polyclonal anti‐koala IgG (for plasma cells) consistently stained lymphoid elements in a wide range of tissues from all four marsupial species. Monoclonal anti‐human CD79a cy (for B cells) stained lymphoid elements in only brushtail possums.

Disseminated Mycobacterium Genavense Infection in a FIV-Positive Cat

An 8-year-old FIV-positive Australian cat was presented with coughing, periocular alopecia, pyrexia and inappetence. Skin scrapings demonstrated Demodex cati mites. Antibiotics were administered and it was treated successfully for periocular demodectic mange, but the cat continued to exhibit respiratory signs and lose weight. Further investigation revealed an ascarid infection and active chronic inflammation of undetected cause affecting the lower airways. Repetitive treatment with pyrantel failed to eradicate the ascarid infection. The cat became cachectic and developed moist ulcerative dermatitis of the neck, severe non-regenerative anaemia, leucopenia and thrombocytopenia. Necropsy and histopathology revealed mycobacteriosis affecting skin, lungs, spleen, lymph nodes, liver and kidney. Attempted culture of frozen tissues at a mycobacteria reference laboratory was unsuccessful. Paraffin-embedded, formalin-fixed tissue was retrieved and examined using PCR to amplify part of the 16S rRNA gene. A diagnosis of disseminated Mycobacterium genavense infection was made based on the presence of acid fast bacteria in many tissues and partial sequence of the 16S rRNA gene. Although M genavense has been identified previously as a cause of disseminated disease in AIDS patients, this is the first report of infection in a cat. It was suspected that the demodecosis, recurrent ascarid infections and disseminated M genavense infection resulted from an immune deficiency syndrome consequent to longstanding FIV infection.

Haematological, biochemical and selected acute phase protein reference intervals for weaned female Merino lambs

BACKGROUND Merino lambs are currently the subject of much research into the welfare aspects of mulesing and mulesing alternatives. OBJECTIVE Obtain haematology, biochemistry and acute phase protein reference intervals using modern methodologies for female Merino lambs. METHOD Blood was collected from 50, weaned, 9- to 16-week-old, female Merino lambs. Haematology and biochemistry panels were performed using routine automated methods. The acute phase proteins, fibrinogen, serum amyloid A and haptoglobin, were also measured using commercially available techniques. The reference intervals were determined to be the central 95% of results. RESULTS Differences in the concentrations for some analytes were seen when compared with reported studies in sheep, but may be explained by the use of sheep of a different signalment, as well as different methodologies for analyte measurement. Overall, most analytes gave similar values to those previously reported in other studies. Notable exceptions were alkaline phosphatase, phosphate and globulins, for which the different results were often attributed to the younger age of the sheep in the present study, and platelets and creatine kinase, for which the elevated levels may have been a result of stress and muscle exertion associated with blood collection and husbandry practices. CONCLUSION Established haematological, biochemical and acute phase protein reference intervals are necessary for the investigation of the systemic impact of mulesing and mulesing alternatives and for the investigation of systemic diseases affecting weaned, 9- to 16-week-old, female Merino lambs in general.

Histopathological and immunohistochemical investigation of naturally occurring chlamydial conjunctivitis and urogenital inflammation in koalas (Phascolarctos cinereus)

Formalin-fixed conjunctival and urogenital (urinary bladder, urogenital sinus and prostate or penis, or both) samples obtained from 29 free-living koalas were examined histopathologically and immunohistochemically for the presence and character of inflammation and for evidence of chlamydiae. Five koalas had no inflammation at any site examined and were chlamydia-negative. Twenty-four koalas had inflammation at one or more sites and 18 were positive for chlamydiae by serology or antigen detection tests, or both. Histopathological and immunohistochemical findings were consistent with those seen in chlamydial infections in other species. The inflammatory infiltrate was most dense in the lamina propria-submucosa and, in most tissues, predominantly consisted of lymphocytes and plasma cells. Neutrophils and macrophages were variable in number. Lymphocytes in uninflamed and inflamed tissues consisted largely of T cells. B lymphocytes and plasma cells were mainly distributed immediately beneath the epithelium, but T cells were widely distributed. MHC H-positive lymphoid cells were present in variable numbers and, in some inflamed tissue samples, epithelial cell labelling was also seen. Chlamydial inclusion bodies were uncommon in routinely stained sections. Immunoperoxidase labelling for chlamydiae was positive in 16 of 52 inflamed tissues. The proportion of positive test results for chlamydial antigen by any method was directly related to the severity of inflammation.

Effect of dietary lipid on UV light carcinogenesis in the hairless mouse.

Abstract— Isocaloric feeding of diets varying in lipid content to albino hairless mice has shown that their susceptibility to skin tumorigenesis induced by simulated solar UV light was not affected by the level of polyunsaturated fat, 5% or 20%. However a qualitative effect of dietary lipid was demonstrated. Mice fed 20% saturated fat were almost completely protected from UV tumorigenesis when compared with mice fed 20% polyunsaturated fat. Multiple latent tumours were detected in the saturated fat‐fed mice by subsequent dietary replenishment, suggesting that a requirement for dietary unsaturated fat exists for the promotion stage of UV‐induced skin carcinogenesis.

Histological and immunohistological investigation of lymphoid tissue in the platypus (Ornithorhynchus anatinus).

The gross and histological appearance and the distribution of T and B lymphocytes and plasma cells are described for lymphoid tissues obtained from 15 platypuses. The spleen was bilobed and surrounded by a thick capsule of collagen, elastic fibres and little smooth muscle. White pulp was prominent and included germinal centres and periarterial lymphoid sheaths. Red pulp contained haematopoietic tissue. A thin lobulated thymus was located within the mediastinum overlying the heart. The cortex of lobules consisted of dense aggregates of small and medium lymphocytes, scattered macrophages and few reticular epithelial cells. In the medulla, Hassalls corpuscles were numerous, lymphocytes were small and less abundant, and reticular cells were more abundant than in the cortex. Lymphoid nodules scattered throughout loose connective tissue in cervical, pharyngeal, thoracic, mesenteric and pelvic sites measured 790±370 μm (mean±S.D., n = 39) in diameter, the larger of which could be observed macroscopically. These consisted of single primary or secondary follicles supported by a framework of reticular fibres. Macrophages were common in the germinal centres. The platypus had a full range of gut‐associated lymphoid tissue. No tonsils were observed macroscopically but histologically they consisted of submucosal follicles and intraepithelial lymphocytes. Peyers patches were not observed macroscopically but histologically they consisted of several prominent submucosal secondary follicles in the antimesenteric wall of the intestine. Caecal lymphoid tissue consisted of numerous secondary follicles in the submucosa and densely packed lymphocytes in the lamina propria. Bronchus‐associated lymphoid tissue was not observed macroscopically but was identified in 7 of 11 platypus lungs assessed histologically. Lymphoid cells were present as primary follicles associated with bronchi, as aggregates adjacent to blood vessels and as intraepithelial lymphocytes. The distribution of T lymphocytes, identified with antihuman CD3 and CD5, and B lymphocytes and plasma cells, identified with antihuman CD79a and CD79b and antiplatypus immunoglobulin, within lymphoid tissues in the platypus was similar to that described in therian mammals except for an apparent relative paucity of B lymphocytes. This study establishes that the platypus has a well‐developed lymphoid system which is comparable in histological structure to that in therian mammals. It also confirms the distinctiveness of its peripheral lymphoid tissue, namely lymphoid nodules. Platypus lymphoid tissue has all the essential cell types, namely T and B lymphocytes and plasma cells, to mount an effective immune response against foreign antigens.

Elevation of immunoglobulin deposition in the synovial membrane of dogs with cranial cruciate ligament rupture

Synovial membrane biopsies were collected from 32 dogs with spontaneous cranial cruciate ligament rupture and seven control dogs. The subclasses of immunoglobulins in the synovial membrane of both the diseased and control dogs were examined with immunohistochemistry in combination with image analysis. IgG deposition was four-fold higher and IgM was eight-fold higher in dogs with spontaneous cranial crucial ligament (CrCL) rupture. These findings support the theory that there is an immune component to the inflammation associated with canine CrCL rupture. Further investigation is required to determine if these immune or inflammatory responses in CrCL rupture joints are the primary factor in ligament rupture or if they develop secondary to ligament rupture and instability.