Somatic evolution and global expansion of an ancient transmissible cancer lineage

The canine transmissible venereal tumor (CTVT) is a cancer lineage that arose several millennia ago and survives by "metastasizing" between hosts through cell transfer. The somatic mutations in this cancer record its phylogeography and evolutionary history. We constructed a time-resolved phylogeny from 546 CTVT exomes and describe the lineage's worldwide expansion. Examining variation in mutational exposure, we identify a highly context-specific mutational process that operated early in the cancer's evolution but subsequently vanished, correlate ultraviolet-light mutagenesis with tumor latitude, and describe tumors with heritable hyperactivity of an endogenous mutational process. CTVT displays little evidence of ongoing positive selection, and negative selection is detectable only in essential genes. We illustrate how long-lived clonal organisms capture changing mutagenic environments, and reveal that neutral genetic drift is the dominant feature of long-term cancer evolution.

Expression of p53 protein, Jaagsiekte sheep retrovirus matrix protein, and surfactant protein in the lungs of sheep with pulmonary adenomatosis

Ovine pulmonary adenocarcinoma (OPA) is a naturally occurring cancer in sheep that is caused by the Jaagsiekte sheep retrovirus (JSRV). Because the pathologic and epidemiologic features of OPA are similar to those of bronchoalveolar carcinoma in humans, OPA is considered a useful animal model for pulmonary carcinogenesis. In this study, 3,512 lungs from various breeds of sheep were collected and macroscopically examined. OPA was identified in 30 sheep, and samples of these animals were further examined by histologic, immunohistochemical (p53 protein, surfactant protein A [SP-A], proliferating cell nuclear antigen [PCNA], JSRV matrix protein [MA]), and PCR methods. Papillary or acinar adenocarcinomas were detected microscopically in the affected areas. Immunoreactivity for p53 PAb240 was detected in 13 sheep, whereas p53 DO-1 was not detected in any of the OPA animals. PCNA immunoreactivity was recorded in 27 animals. SP-A and JSRV MA protein was immunopositive in all 30. JSRV proviral DNA was detected by PCR analysis in all of the lung samples collected from OPA animals. In addition, the pulmonary SP-A levels were increased in tumor cells. The results of this study suggest that PCNA and p53 protein expression may be useful indicators in monitoring malignancy of pulmonary tumors.

Rat liver fibrosis regresses better with pegylated interferon alpha2b and ursodeoxycholic acid treatments than spontaneous recovery

BACKGROUND/AIMS

Fibrosis and cirrhosis are common complications of chronic liver diseases. An imbalance between fibrogenesis and fibrolysis results in scarring of the liver parenchyma. We aimed to investigate the possible antifibrotic effectiveness of a newly modified interferon molecule peginterferon alpha2b (PEG-IFNalpha2b) which has better antiviral activity, and ursodeoxycholic acid (UDCA).

METHODOLOGY

Liver fibrosis was established on 60 male Sprague Dawley rats with CCl4 in 12 weeks. After cessation of CCl4 Group I was left for spontaneous recovery. Group II was treated with PEG-IFN 1.5 microg/kg/week, Group III with UDCA 25 mg/kg/day and Group IV with combination of both drugs. All rats were killed at week 16. Histopathologic fibrosis scores, tissue hydroxyproline, TIMP-1 and MMP-13 levels were determined. Hepatic stellate cell apoptosis was detected by dual staining with TUNEL technique and anti-alpha smooth muscle actin.

RESULTS

Fibrosis scores were lower in Group II, III and IV than Group I (p<0.05 for group I vs. II and III; p<0.01 for group I vs. IV). Tissue hydroxyproline levels were significantly decreased in Group II, III and IV when compared to Group I (p<0.05 for group I vs. II, p<0.01 for group I vs. III and IV). Lower liver TIMP-1 and higher MMP-13 levels were measured in Group II, III, and Group IV than Group I (p<0.01 for TIMP-1 and p<0.01, for MMP). Activated HSC apoptosis was significantly increased in Group II, III and IV when compared to Group I (p<0.01, for all). There was significantly higher apoptosis in Group II than Group III and IV (p<0.01).

CONCLUSION

Treatment with both PEG-IFNalpha2b and UDCA improved CCl4 induced rat liver fibrosis. Significantly higher effects were obtained using these agents in combination.

Diffuse mesenteric lipodystrophy (massive fat necrosis) in a cat

Clinical, radiographic, and pathological findings of diffuse mesenteric lipodystrophy in a 3-year-old, female domestic short-haired cat are described. The animal had fallen from a height of approximately 20 metres 6 weeks previously, after which it developed respiratory distress and anorexia. The cat was thin, exhausted and had rapid, shallow, open-mouthed breathing. Serial upper gastrointestinal contrast radiographs showed a prolonged transit time of the contrast medium due to restricted gastric emptying, and filling defects of the duodenojejunal portions of the small intestines. The cranial abdominal cavity contained large, firm, white masses that adhered to most of the anterior abdominal organs. The intestinal walls were completely surrounded by large, hard, lobulated masses of lipomatous tissue. The masses were characterised histologically by extensive areas of coagulative necrosis of adipocytes containing foci of saponification. The lesions resembled those of massive fat necrosis or lipomatosis in cattle, pigs and deer.

Generalized tuberculosis in a 45 day-old calf

The objectives of the present study were to describe pathomorphological and immunohistochemical features of generalized natural tuberculosis in a 45 day-old female calf. The characteristic lesion of tuberculosis was productive type which was located in the lung, liver, and especially in the lymph nodes (mediastinal, bronchial, mesenterial, portal, prescapular, renal and caudal sternal lymph nodes). Mycobacterium bovis antigens were seen generally in the cytoplasma and around the macrophages, rarely in necrotic areas and Langhans giant cells by avidin-biotin complex peroxidase method.

Immunohistochemical and histopathological studies of fixed rabies virus in goats

The purpose of this study was to systematically demonstrate and compare the pathological and immunohistochemical changes in goats which were infected by a fixed rabies virus that was used in vaccine production. In the histopathological examinations, varying degrees of inflammatory, degenerative and necrotic changes were detected in the central nervous system. In the preparations stained by the immunoperoxidase (IP) method, intra- and/or extracellular viral antigens were observed on the cerebellum, cornu ammonis, thalamus, pons, nucleus caudatus, spinal cord, medulla oblongata, Gasserian ganglion, eye and retropharyngeal lymph nodes. In the preparations stained by the immunofluorescence (IF) method, intra- and/or extracellular viral antigens were seen in the same locations with the exception of the retropharyngeal lymph nodes. It was also observed that the antigens were qualitatively and quantitatively well stained with both methods. However, the visibility of antigens in the retropharyngeal lymph nodes and eye, and the facilities of applying made the IP method much more advantageous than the IF method.