Glioblastoma multiforme: clinical findings, magnetic resonance imaging, and pathology in five dogs

Although glioblastoma multiforme (GBM), a World Health Organization grade IV astrocytoma, is the most common primary brain tumor in humans, in dogs GBM is relatively rare, accounting for only about 5% of all astrocytomas. This study presents combined clinical, neuroimaging, and neuropathologic findings in five dogs with GBM. The five dogs, aged from 5 to 12 years, were presented with progressive neurologic deficits that subsequent clinical neurologic examination and neuroimaging studies by magnetic resonance imaging (MRI), localized to space occupying lesions in the brain. MRI features of the tumors included consistent peritumoral edema (n = 5), sharp borders (n = 4), ring enhancement (n = 3), heterogenous T2-weighted signal intensity (n = 3), iso- to hypointense T1-weighted images (n = 5), necrosis (n = 5), and cyst formation (n = 2). Two tumors were diagnosed clinically using a computed tomography-guided stereotactic biopsy procedure. At necropsy all the tumors resulted in, on transverse sections, a prominent midline shift and had a variegated appearance due to intratumoral necrosis and hemorrhage. Histologically, they had serpentine necrosis with glial cell pseudopalisading and microvascular proliferation, features which distinguish human GBM from grade III astrocytomas. Immunoreactivity of tumor cells for glial fibrillary acidic protein was strongly positive in all cases, whereas 60% and 40% of the tumors also expressed epidermal growth factor receptor and vascular endothelial growth factor, respectively. These canine GBMs shared many diagnostic neuroimaging, gross, microcopic, and immunoreactivity features similar to those of human GBMs.     

Canine intraspinal meningiomas: imaging features, histopathologic classification, and long-term outcome in 34 dogs

BACKGROUND: Meningioma is the most common primary intraspinal nervous system tumor in dogs. Clinical findings, clinicopathologic data, and treatment of these tumors have been reported sporadically, but little information is available regarding cerebrospinal fluid (CSF) analysis, histologic tumor grade, or efficacy of radiation therapy as an adjunct to cytoreductive surgery. ANIMALS: Dogs with histologically confirmed intraspinal meningiomas (n = 34). METHODS: A retrospective study of dogs with intraspinal meningiomas between 1984 and 2006 was carried out. Signalment, historical information, physical examination, clinicopathologic data, radiation therapy protocols, surgery reports, and all available images were reviewed. All tumors were histologically classified and graded as defined by the international World Health Organization classification scheme for central nervous system tumors. RESULTS: Intraspinal mengiomas in dogs are most common in the cervical spinal cord but can be found throughout the neuraxis. Location is correlated with histologic grade, with grade I tumors more likely to be in the cervical region than grade II tumors. Myelography generally shows an intradural extramedullary compressive lesion. On magnetic resonance imaging, the masses are strongly and uniformly contrast enhancing and a dural tail often is present. CSF analysis usually shows increased protein concentration with mild to moderate mixed pleocytosis. Surgical resection is an effective means of improving neurologic status, and adjunctive radiation therapy may lead to an improved outcome. CONCLUSIONS AND CLINICAL IMPORTANCE: Biopsy is necessary for definitive diagnosis, but imaging and CSF analysis can suggest a diagnosis of meningioma. Treatment of meningiomas with surgery and radiation therapy can result in a fair to excellent prognosis.     

Magnetic resonance imaging and histological classification of intracranial meningiomas in 112 dogs

BACKGROUND: Intracranial meningiomas are the most common primary brain tumors in dogs. Classification of meningiomas by tumor grade and subtype has not been reported, and the value of magnetic resonance imaging (MRI) characteristics for predicting tumor subtype and grade has not been investigated. HYPOTHESIS: Canine intracranial meningiomas are a heterogenous group of tumors with differing histological subtypes and grades. Prediction of histopathological classification is possible based on MRI characteristics. ANIMALS: One hundred and twelve dogs with a histological diagnosis of intracranial meningioma. METHODS: Retrospective observational study. RESULTS: Meningiomas were overrepresented in the Golden Retriever and Boxer breeds with no sex predilection. The incidence of specific tumor grades was 56% benign (Grade I), 43% atypical (Grade II), and 1% malignant (Grade III). Grade I histological subtypes included meningothelial (43%), transitional (40%), microcystic (8%), psammomatous (6%), and angiomatous (3%). No statistically significant (P < .05) associations were found among tumor subtype or grade and any of the MRI features studied. CONCLUSIONS AND CLINICAL IMPORTANCE: Meningiomas in dogs differ from their counterparts in humans mainly in their higher incidence of atypical (Grade II) tumors observed. MRI characteristics do not allow for prediction of meningioma subtype or grade, emphasizing the necessity of histopathology for antemortem diagnosis. The higher incidence of atypical tumors in dogs may contribute to the poorer therapeutic response in dogs with meningiomas as compared with the response in humans with meningiomas.     

Modeling the Exchanges of Energy, Water, and Carbon Between Continents and the Atmosphere

Atmospheric general circulation models used for climate simulation and weather forecasting require the fluxes of radiation, heat, water vapor, and momentum across the land-atmosphere interface to be specified. These fluxes are calculated by submodels called land surface parameterizations. Over the last 20 years, these parameterizations have evolved from simple, unrealistic schemes into credible representations of the global soil-vegetation-atmosphere transfer system as advances in plant physiological and hydrological research, advances in satellite data interpretation, and the results of large-scale field experiments have been exploited. Some modern schemes incorporate biogeochemical and ecological knowledge and, when coupled with advanced climate and ocean models, will be capable of modeling the biological and physical responses of the Earth system to global change, for example, increasing atmospheric carbon dioxide.     

Linkage of the gene for the scrapie-associated fibril protein (PrP) to the Sip gene in Cheviot sheep

The gene Sip with two alleles, sA and pA, is the major gene determining the incubation period of scrapie in its natural host, sheep. Two lines of Cheviot sheep have been bred which differ in their response to experimental infection with SSBP/1 scrapie. The negative line have a decreased incidence of disease caused by SSBP/1 and are SippApA. The positive line have an increased incidence of disease and the majority are either SipsAsA or SipsApA; it is not possible to distinguish between the two genotypes on the basis of scrapie incubation time because the sA allele is fully dominant with SSBP/1 scrapie. There are also rare SippApA segregants in the positive line. The major protein (PrP) of scrapie-associated fibrils is encoded by a cellular gene and a cDNA copy of the hamster PrP mRNA has been used to analyse the restriction fragment length polymorphism of the two lines of Cheviot sheep. Two polymorphisms of the sheep PrP gene were found, by using HindIII and EcoRI, which appear to act as markers for the alleles of Sip. Using these polymorphisms it is now possible to assign a Sip genotype to the sheep in the Cheviot flock. Preliminary results from Anglo-Nubian goats and a cow are also reported.     

Use of terminal restriction fragment length polymorphism (T-RFLP) for identification of phytoplasmas in plants

A terminal restriction fragment analysis (T-RFLP) technique was developed for the simple and rapid detection and diagnosis of phytoplasmas in plants. The selected primers amplified part of the 23S rRNA gene to provide improved resolution between the taxonomic groups compared to conventional restriction enzyme analysis of the 16S rRNA. Using the restriction enzymes Bsh 12361 and Mse I on the PCR products, and fragment analysis in the range 68–640 bp, the technique was tested on 37 isolates from 10 of the 16Sr groups. Distinct and unambiguous T-RFLP profiles were produced for nine of the 10 taxonomic groups, such that almost all isolates within a group shared the same profile and could be distinguished from isolates in other groups. The technique also identified the presence of mixtures of phytoplasmas from different groups in samples. Furthermore, the primers were devised to amplify a terminal restriction fragment (TRF) product of a specific defined size (461 bp) from the host plant chloroplast DNA, so that there was a built-in internal control in the procedure to show that the absence of a phytoplasma peak in a sample was the result of no detectable phytoplasma being present, not the result of PCR inhibition. This method offers the possibility of simultaneously detecting and providing a taxonomic grouping for phytoplasmas in test samples using a single PCR reaction.     

RADIATION INDUCED VERTEBRAL OSTEOSARCOMA FOLLOWING TREATMENT OF AN INTRADURAL EXTRAMEDULLARY SPINAL CORD TUMOR IN A DOG

A 2-year-old neutered female Rottweiler diagnosed with an intradural extramedullary spinal cord tumor at T12-T13 was successfully treated with cytoreductive surgery followed by Cobalt 60 teletherapy. The dog was euthanised 5-and-a-half years later following diagnosis of an osteosarcoma involving the L1 and L2 vertebrae. Evidence of the initial tumor was not present at necropsy. The vertebral neoplasm fulfilled all of the accepted criteria for a radiation induced tumor. It was concluded that adjunctive irradiation should be considered for treatment of intradural extramedullary tumors of young dogs when total surgical resection is not possible. Although tumor induction is a rare late effect of radiation therapy, the risk of this occurrence should be considered when irradiating young animals. Radiation induced tumors in dogs have been associated with coarse fractionation schemes, or when large intraoperative doses have been administered. A lower dose per fraction, e.g., 3 Gy/fraction or less, is advisable when irradiating young dogs or any dog in which the life expectancy is 3-5 or more years after irradiation.