Abstract
Skin samples from twenty-nine cases of naturally occurring, serologically confirmed, canine leishmaniasis were examined by H&E staining, immunohistochemistry (IHC) for Leishmania amastigotes, and polymerase chain reaction (PCR) for Leishmania DNA. Skin biopsies showed a chronic mononuclear inflammatory infiltrate with a wide range of severity. The sensitivity of PCR was 82.8%, IHC was 62.1% and H&E was 44.8% for detection of organisms. Samples were obtained from the ear, nose and abdomen. Results from the various anatomic sites did not reveal any statistically significant differences although parasites were more easily detected in samples from the ear than from the nose or abdomen. All three techniques yielded positive results even in asymptomatic dogs. The authors conclude that PCR is the best method for diagnosing Leishmania infection from paraffin-embedded tissues. Obtaining skin samples from the ear appears to be sufficient and is usually less traumatic than samples from the nose or abdomen.
Xavier SC, Andrade HM, Hadad SJ. Comparison of paraffin-embedded skin biopsies from different anatomical regions as sampling methods for detecting Leishmania infection in dogs using histological, immunohistochemical and PCR methods. BMC Vet Res
It has been known for many years that ingestion of bracken fern (Pteridium aquilinum) is associated with bladder tumors in cattle, likely due in part to the ptaquiloside toxin in the plant. The authors of this report studied bladders from 433 cattle that were rejected at slaughter due to bladder lesions at an abattoir in São Miguel Island, where bracken fern grows in pastures. Ninety percent of the cattle had hematuria. From the 433 cattle they analyzed 1337 tissue sections in order to classify the spectrum of bladder lesions associated with bracken fern. Lesions were classified as inflammatory lesions, non-neoplastic epithelial abnormalities, and tumors. Inflammatory lesions included polypoid and follicular cystitis. The most frequent non-neoplastic epithelial abnormalities were transitional cell hyperplasia, von Brunn's nests, cystitis cystica and glandular metaplasia. These were often associated with neoplastic conditions. Tumors were present in 870 of the lesions examined, and more than half of the bladders contained multiple tumors. The majority (62%) was of epithelial origin, and 52% were malignant. Transitional cell carcinoma was the most frequent malignant tumor, while hemangioma was the most frequent mesenchymal tumor. The authors described several growth patterns that were not previously reported in bladders of cattle, such as inverted papilloma and papillary neoplasms of apparently low malignant potential.
Carvalho T, Pinto C, Peleteiro MC. Urinary bladder lesions in bovine enzootic haematuria. J Comp Pathol
Several studies have implicated antibiotic use as a risk factor in development of breast cancer in humans. In this study HER-2/neu transgenic mice were used to evaluate the effects of long-term exposure to gentamicin or metronidazole/ciprofloxacin in drinking water. Mice receiving metronidazole/ciprofloxacin were three times more likely to develop mammary tumors than controls, while mice receiving gentamicin had only a slightly higher rate of tumor occurrence. However, the tumors in mice receiving gentamicin grew much faster than those in control mice. Furthermore, mice in both antibiotic groups showed morphologic changes in their mammary glands, including increased numbers of lobules and increased ductal branching. Those in the metronidazole/ciprofloxacin group also had epithelial hyperplasia which reduced the lumens of the buds. The mechanism by which antibiotic administration influences mammary tissue growth is not known, but the authors speculate that it may be related to alterations in normal intestinal flora with secondary effects on estrogen-related metabolites.
Rossini A, Rumio C, Sfondrini L, et al. Influence of antibiotic treatment on breast carcinoma development in Proto-neu transgenic mice. Cancer Res
Feline mesotheliomas are rare tumors with morphologic variants of epithelioid, fibrosarcomatous (fibrous), or biphasic types. For these reasons, they often present a diagnostic challenge. The authors of this study performed immunohistochemical analysis on ten cases of feline mesothelioma and ultrastructural analyses on four of these cases in order to determine which of these modalities may be useful as a diagnostic adjunct to routine H&E staining. Eight of ten cases involved the pleura, and six tumors had metastasized. Similar to canine and human mesotheliomas, all tumors showed positive staining for both cytokeratin AE1/AE3 and vimentin. Two tumors were positive for cytokeratin 5/6 and three were positive for carcinoembryonic antigen (CEA). Six samples (five epithelioid type and one fibrous type) were positive for HBME-1, an antibody that reacts with an antigen on both normal and neoplastic mesothelial microvilli. All tumors were negative for desmin and calretinin. Ultrastructural analysis on four epithelioid tumors showed abundant microvilli, intercellular desmosomal attachments and intermediate filaments. The authors conclude that dual positivity for cytokeratin AE1/AE3 and vimentin is a useful tool in the diagnosis of feline mesothelioma. HMBE-1 may be useful in cases where reactive hyperplasia can be ruled out, as it would also give a positive result. Ultrastructural examination can be useful in determining the cell of origin.
Bacci B, Morandi F, De Meo M, Marcato PS. Ten cases of feline mesothelioma: An immunohistochemical and ultrastructural study. J Comp Pathol
Texel sheep are noted for their muscle development and leanness. Investigators sought to determine the genetic basis for these economically important traits. Their initial genome scan indicated potential involvement of the myostatin (GDF8) gene but no significant differences in the coding region were found when Texel sheep were compared to other breeds. The authors then discovered a guanine to adenosine (G to A) transition in the myostatin 3′ untranslated region which creates a target site for two microRNAs highly expressed in skeletal muscle. MicroRNAs have recently received much attention due to their wide-ranging effects in normal development and in various disease conditions. MicroRNAs are short (19–25 basepair) non-protein-coding RNAs that regulate expression of many messenger RNAs. In Texel sheep the interaction between microRNAs and the altered target site in the myostatin 3′ untranslated region results in reduced myostatin protein in skeletal muscle cells, leading to muscular hypertrophy.
Clop A, Marcq F, Takeda H, et al. A mutation creating a potential illegitimate microRNA target site in the myostatin gene affects muscularity in sheep. Nat Genet