Lower face asymmetry as a marker for developmental instability.

OBJECTIVES: Fluctuating asymmetries in the craniofacial skeleton have been shown to be predictive for mortality from degenerative diseases. We investigate whether lower face asymmetries are a potential marker for the developmental origins of health and disease. METHODS: The lower face of a representative sample of 6654 12- to 17-year old United States (US) adolescents (1966-1970, National Health Examination Survey III) was classified as asymmetric when the mandibular teeth occluded prognathically (forward) or retrognathically (backward) on one side of the face only. It was investigated whether these lower face asymmetries were directional (preferentially to the left or the right) or fluctuating (random left-right distribution) in the US population. RESULTS: Lower face asymmetries affected 1 in 4 of the US adolescents. Unilateral retrognathic dental occlusions were fluctuating asymmetries, had a US prevalence of 17.0% (95% confidence interval: 15.5-18.4) and were associated with race/ethnicity (P < .0001), not with handedness (P < .7607). Unilateral prognathic dental occlusions were directional asymmetries (P < .0001), had a US prevalence of 7.6% (95% confidence interval: 6.4-8.7) and were associated with large household size (P < .001) and handedness (P < .0223). Lower face asymmetries were not associated with distinct heritable traits such as color blindness. CONCLUSIONS: The findings suggest that lower face asymmetries are a marker for environmental stress and cerebral lateralization during early development.

Canine Nervous System Lymphoma Subtypes Display Characteristic Neuroanatomical Patterns.

Primary and secondary nervous system involvement occurs in 4% and 5%-12%, respectively, of all canine non-Hodgkin lymphomas. The recent new classification of canine malignant lymphomas, based on the human World Health Organization classification, has been endorsed with international acceptance. This histological and immunocytochemical classification provides a unique opportunity to study the histologic anatomic distribution patterns in the central and peripheral nervous system of these defined lymphoma subtypes. In this study, we studied a cohort of 37 dogs with lymphoma, which at necropsy had either primary (n = 1, 2.7%) or secondary (n = 36; 97.3%) neural involvement. These T- (n = 16; 43.2%) or B-cell (n = 21; 56.8%) lymphomas were further classified into 12 lymphoma subtypes, with predominant subtypes including peripheral T-cell lymphoma (PTCL) or diffuse large B-cell lymphoma (DLBCL), respectively. This systematic study identified 6 different anatomically based histologically defined patterns of lymphoma infiltration in the nervous system of dogs. Different and distinct combinations of anatomical patterns correlated with specific lymphoma subtypes. Lymphoma infiltration within the meningeal, perivascular, and periventricular compartments were characteristic of DLBCL, whereas peripheral nerve involvement was a frequent feature of PTCL. Similarly cell counts above 64 cells/µL in cerebrospinal samples correlated best with marked meningeal and periventricular lymphoma infiltration histologically. Prospective studies are needed in order to confirm the hypothesis that these combinations of histological neuroanatomic patterns reflect targeting of receptors specific for the lymphoma subtypes at these various sites.

Phenotypic characteristics of adolescents with concave and convex facial profiles - The National Health Examination Survey.

It has been suggested that facial traits are informative on the inherited susceptibility to tuberculosis and obesity, two current global health issues. Our aim was to compare the phenotypic characteristics of adolescents with dental markers for a concave (n=420), a convex (n=978), and a straight (n=3542) facial profile in a nationally representative sample of United States adolescents. The results show that adolescents with a concave facial profile, when compared to a straight facial profile, had an increased waist-to-height ratio (Δ, 1.1 [95% CI 0.5-1.7], p<0.003) and an increased acne prevalence (OR, 1.5 [95% CI 1.2-1.9], p<0.001). Adolescents with a convex facial profile, when compared to a straight facial profile, had an increased prevalence of tuberculosis (OR, 4.3 [95% CI 1.4-13.1], p<0.02), increased ectomorphy (Δ, 0.3 [95% CI 0.2-0.4], p<0.0001), increased left-handedness (OR, 1.4 [95% CI 1.1-1.7], p<0.007), increased color-blindness (OR, 1.7 [95% CI 1.3-2.3], p<0.004), and rhesus ee phenotype (OR, 1.3 [95% CI 1.1-1.5], p<0.008). Adolescents with a concave facial profile, when compared to a convex profile, had increased mesomorphy (Δ, 1.3 [95% CI 1.1-1.5], p<0.0001), increased endomorphy (Δ, 0.5 [95% CI 0.4-0.6], p<0.0001), lower ectomorphy (Δ, 0.5 [95% CI 0.4-0.6], p<0.0001), and lower vocabulary test scores (Δ, 2.3 [95% CI 0.8-3.8], p<0.008). It is concluded that population-based survey data confirm that distinct facial features are associated with distinct somatotypes and distinct disease susceptibilities.

Cephalometric analysis and long-term outcomes of orthognathic surgical treatment for obstructive sleep apnoea.

The aim of this study was to describe skeletal and posterior airway changes after orthodontic treatment and surgical jaw advancement, and to evaluate whether there is a correlation between increasing advancement and a long-term reduction in obstructive sleep apnoea (OSA). Lateral cephalograms and polysomnography (apnoea-hypopnoea index, AHI) were collected from patients treated with bilateral sagittal split osteotomy (BSSO) or maxillomandibular advancement (MMA) in combination with orthodontics. Patients completed a questionnaire and the Epworth Sleepiness Scale (ESS) to assess long-term outcomes. Descriptive statistics for cephalometric measurements and linear regression were performed to find estimates of the final OSA (AHI and ESS) as a function of mandibular advancement. Forty-three patients with surgical advancement of the maxilla (5.2mm) and mandible (8.3mm) had a 4-mm increase in posterior airway. Thirty-three patients completed the long-term survey (6.3±2.6 years after treatment); 91% reported a reduction of OSA and were pleased with their facial appearance. The maxillomandibular and posterior airway increased. There was no evidence of a linear relationship between greater amounts of mandibular advancement and improvement of OSA. Patients with less than 10mm advancement had successful objective short-term and subjective long-term OSA reduction.

Bilaterally symmetric focal cortical dysplasia in a golden retriever dog.

A 10-year-old golden retriever dog was referred with a 24-h history of generalized seizures. Magnetic resonance imaging of the brain found no abnormalities on 3 mm transverse sections and the dog was subsequently humanely destroyed. Microscopically there was bilaterally symmetrical focal disorganization of cortical grey matter within the tips of the right and left suprasylvian gyri of the temporal cortex. The focal abnormal cortical lamination was characterized by loss of pyramidal neurons with abnormal, irregular, angular, remaining neurons occasionally forming clusters, surrounded by fibrillary astrogliosis and microgliosis and vascular proliferation. These histological findings are consistent with focal cortical dysplasia, a cerebral cortical malformation that causes seizures in people, but not reported previously in the dog.

Temporal and geographic clustering of polyomavirus-associated olfactory tumors in 10 free-ranging raccoons (Procyon lotor).

Reports of primary nervous system tumors in wild raccoons are extremely rare. Olfactory tumors were diagnosed postmortem in 9 free-ranging raccoons from 4 contiguous counties in California and 1 raccoon from Oregon within a 26-month period between 2010 and 2012. We describe the geographic and temporal features of these 10 cases, including the laboratory diagnostic investigations and the neuropathologic, immunohistochemical, and ultrastructural characteristics of these tumors in the affected animals. All 9 raccoons from California were found within a localized geographic region of the San Francisco Bay Area (within a 44.13-km radius). The tight temporal and geographic clustering and consistent anatomic location in the olfactory system of tumor types not previously described in raccoons (malignant peripheral nerve sheath tumors and undifferentiated sarcomas) strongly suggest either a common cause or a precipitating factor leading to induction or potentiation of neuro-oncogenesis and so prompted an extensive diagnostic investigation to explore possible oncogenic infectious and/or toxic causes. By a consensus polymerase chain reaction strategy, a novel, recently reported polyomavirus called raccoon polyomavirus was identified in all 10 tumors but not in the normal brain tissue from the affected animals, suggesting that the virus might play a role in neuro-oncogenesis. In addition, expression of the viral protein T antigen was detected in all tumors containing the viral sequences. We discuss the potential role of raccoon polyomavirus as an oncogenic virus.

Clear cell ependymoma in a dog.

A 13-year-old, mixed breed dog presented with a 1-month history of seizures. Magnetic resonance imaging of the brain revealed a 2.2 × 1.0 × 0.9 cm ovoid and elongate cystic mass within the white matter of the left frontal lobe extending caudally from the cribriform plate to the rostral left lateral ventricle. Three fractions of stereotactic radiotherapy were administered and resulted in reduction of the volume of the tumour; however, the clinical signs failed to improve. On post-mortem examination, a single mass 1.5 × 0.3 × 1 cm was found within the left frontal lobe. It consisted of gelatinous, grey, friable tissue bordering a central empty cavity. Microscopical evaluation revealed polygonal neoplastic cells with distinct cytoplasmic borders and one or more intracytoplasmic solid, brightly eosinophilic, sharply defined globules. Immunohistochemically, the neoplastic cells expressed glial fibrillary acidic protein and S100 but were negative for pan cytokeratin, vimentin, olig-2 and synaptophysin. Ultrastructurally, neoplastic cells had dense whorls of intracytoplasmic intermediate filaments and were connected by multiple intermittent long zonula adherens-type junctions. Based on these findings, a diagnosis of clear cell ependymoma was made. This is the first report of this subtype in the dog.

A grade IV glioblastoma with an oligodendroglial component (GBM-O) in a horse.

A 4-year-old Dutch warmblood mare was presented with a 10-month history of ataxia and proprioceptive deficits. Computed tomography defined a large, non-contrast enhancing mass in the left cerebral hemisphere. Necropsy examination revealed a tumour that effaced much of the piriform and temporal lobes. Microscopically the lesion was classified as a grade IV glioblastoma with an oligodendroglial component (GBM-O). The tumour was composed of highly pleomorphic cells organized in different patterns within a fibrillary stroma. There were multiple foci of necrosis. At the periphery of the tumour neoplastic oligodendroglioma-like cells were embedded in an extracellular mucinous matrix. Most neoplastic cells were strongly immunoreactive for glial fibrillary acidic protein; however, the oligodendroglioma cells did not express this marker. Cells forming microvascular proliferations were positively labelled for expression of factor VIII and smooth muscle actin. All neoplastic cells were negative for Neu-N and synaptophysin. The proliferation index was up to 5%. All neoplastic cells and normal brain tissue from the horse were uniformly negative for expression of epidermal growth factor receptor (EGFR), EGFR vIII mutant and the phosphatase and tensin homologue (PTEN) compared with positive control human GBM tissue. To our knowledge this is the first report of a GBM-O in the horse.

Expression of the tumor suppressor genes NF2, 4.1B, and TSLC1 in canine meningiomas.

Meningiomas are common primary brain tumors in dogs; however, little is known about the molecular genetic mechanisms involved in their tumorigenesis. Several tumor suppressor genes have been implicated in meningioma pathogenesis in humans, including the neurofibromatosis 2 (NF2), protein 4.1B (4.1 B), and tumor suppressor in lung cancer-1 (TSLC1) genes. We investigated the expression of these tumor suppressor genes in a series of spontaneous canine meningiomas using quantitative real-time reverse transcription polymerase chain reaction (RT-PCR) (NF2; n = 25) and western blotting (NF2/merlin, 4.1B, TSLC1; n = 30). Decreased expression of 4.1B and TSLC1 expression on western blotting was seen in 6/30 (20%) and in 15/30 (50%) tumors, respectively, with 18/30 (60%) of meningiomas having decreased or absent expression of one or both proteins. NF2 gene expression assessed by western blotting and RT-PCR varied considerably between individual tumors. Complete loss of NF2 protein on western blotting was not seen, unlike 4.1B and TSLC1. Incidence of TSLC1 abnormalities was similar to that seen in human meningiomas, while perturbation of NF2 and 4.1B appeared to be less common than reported for human tumors. No association was observed between tumor grade, subtype, or location and tumor suppressor gene expression based on western blot or RT-PCR. These results suggest that loss of these tumor suppressor genes is a frequent occurrence in canine meningiomas and may be an early event in tumorigenesis in some cases. In addition, it is likely that other, as yet unidentified, genes play an important role in canine meningioma formation and growth.

Detection of post-menopausal women with low bone mineral density and elevated biochemical markers of bone turnover by panoramic radiographs.

OBJECTIVES: The detection of an eroded mandibular cortex on panoramic radiographs and questionnaire-based screening tools show similar diagnostic efficacies for identifying osteoporosis in post-menopausal women. We evaluated whether both tools also have similar diagnostic performances in identifying women with osteoporosis and elevated biochemical markers of bone turnover who have a high risk of fracture. METHODS: Urinary N-telopeptide cross-links of type I collagen (NTx) (corrected for creatinine) and serum levels of total non-bone-specific alkaline phosphatase (ALP) were measured in 99 post-menopausal women aged 44-70 years (mean +/- standard deviation (SD), 54.6 +/- 5.2 years) who underwent bone mineral density (BMD) assessment and panoramic radiography. BMD was measured at the lumbar spine and femoral neck using dual energy X-ray absorptiometry. The Female Osteoporosis Self-assessment Tool for Asia (FOSTA), which is based on age and weight, was used as the questionnaire-based screening tool. Osteoporosis was defined as a BMD T-score of -2.5 or less at either the lumbar spine or the femoral neck. RESULTS: Urinary NTx and serum ALP were significantly associated with cortical erosion, but not with the FOSTA. The areas under the receiver operating characteristics (ROC) curve for identifying participants with osteoporosis were 0.784 for FOSTA and 0.827 for the detection of cortical erosion, and for identifying participants with osteoporosis and elevated urinary NTx they were 0.700 for FOSTA and 0.807 for the detection of cortical erosion. CONCLUSIONS: Our results suggest that panoramic radiography is superior to questionnaire-based screening for identifying women who are at high risk of fracture.

Choroid plexus tumors in 56 dogs (1985-2007).

BACKGROUND: Choroid plexus tumors (CPTs) comprise approximately 10% of all primary brain tumors in dogs. The clinical utility of magnetic resonance imaging (MRI), cerebrospinal fluid (CSF) analysis, or both in the presumptive diagnosis of CPTs has not been determined. OBJECTIVES: To report MRI and CSF findings in dogs with CPT and determine if there are distinguishing features that allow clinical discrimination between the tumor grades. ANIMALS: Fifty-six client-owned dogs with naturally occurring CPT. METHODS: Retrospective case series. The inclusion criterion was histologically confirmed CPT. Blinded review of cranial MRI and cisternal CSF analysis was performed. RESULTS: Thirty-six of 56 dogs had a choroid plexus carcinoma (CPC) and 20 had a choroid plexus papilloma (CPP). Golden Retrievers were overrepresented compared with the hospital population (frequency 3.7 times that expected, confidence interval 95%= 2.0-6.7, P< .0002). Median CSF protein concentration in CPCs (108 mg/dL, range 27-380 mg/dL) was significantly higher than in CPPs (34 mg/dL, range 32-80 mg/dL) (P= .002). Only dogs with CPCs had a CSF protein concentration >80 mg/dL. Cytological evidence of malignancy in CSF was seen in 7 of 15 CPCs. Only CPCs had evidence of intraventricular or subarachnoid metastases on MRI. CONCLUSIONS AND CLINICAL IMPORTANCE: MRI, CSF analysis or both can help to differentiate between CPPs and CPCs, and may provide valuable prognostic and pretreatment information.

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.

Vascular endothelial growth factor mRNA expression and peritumoral edema in canine primary central nervous system tumors.

Vascular endothelial growth factor (VEGF) is an important regulator of tumor angiogenesis and vascular permeability, and has been implicated both in progression of central nervous system (CNS) tumors and development of vasogenic peritumoral edema. A retrospective study was done to characterize the levels of expression of the 3 major canine VEGF isoforms (VEGF(120), VEGF(164), VEGF(188)) in a variety of spontaneous canine CNS tumors using quantitative TaqMan reverse transcription real-time polymerase chain reaction. Presence and degree of peritumoral edema also were determined in sampled tumors using magnetic resonance imaging (MRI). Increased expression of VEGF relative to normal cerebral cortex tissue was seen predominantly in high grade astrocytic (grade IV) and oligodendroglial (grade III) tumors, with lower expression in low grade astrocytomas (grade II) and meningiomas (grade I). All 3 major VEGF isoforms were present; VEGF(164) was the predominant isoform, particularly in the tumors with the highest VEGF expression. Peritumoral edema was present in all tumor types; however, a significant association between the extent of peritumoral edema and the level of VEGF expression was not apparent.

Tuberculous meningoencephalitis in a pregnant woman presenting 7 years after removal of a cerebral granuloma.

We describe the unusual case of a young woman with a history of seizures and a granulomatous, likely tuberculous brain lesion that was surgically removed. She had an uneventful recovery without any additional therapy other than anti-epileptics. Seven years later, she presented during pregnancy with culture-confirmed tuberculous meningoencephalitis. This case highlights the spectrum of tuberculous central nervous system disease and the challenges in diagnosis.

Mercury speciation analyses in HgCl(2)-contaminated soils and groundwater--implications for risk assessment and remediation strategies.

Since the 19th century, mercury(II)chloride (HgCl(2)) has been used on wood impregnation sites to prevent wooden poles from decay, leaving behind a legacy of highly contaminated soil/aquifer systems. Little is known about species transformation and mobility of HgCl(2) in contaminated soils and groundwater. At such a site the behaviour of HgCl(2) in soils and groundwater was investigated to assist in risk assessment and remediation. The soil is low in organic carbon and contains up to 11,000 mg Hg/kg. Mercury (Hg) concentrations in groundwater decrease from 230 to 0.5 microg/l within a distance of 1.3 km. Hg species transformations in soil and aqueous samples were analysed by means of solid-phase Hg pyrolysis and CV-AAS. In aqueous samples, Hg species were distinguished between ionic/reactive Hg and complex-bound Hg. Potential mobility of Hg in soils was studied through batch experiments. Most Hg in the soil is matrix-bound HgCl(2), whereas in the aquifer secondary formation to Hg(0) could be observed. Aqueous Hg speciation in groundwater and soil solutions shows that an average of 84% of soluble Hg exists as easily reducible, inorganic Hg species (mostly HgCl(2)). The proportion of complex-bound Hg increases with distance due to the transformation of inorganic HgCl(2). The frequent occurrence of Hg(0) in the aquifer suggests the formation and degassing of Hg(0), which is, in addition to dilution, an important process, lowering Hg concentrations in the groundwater. High percentage of mobile Hg (3-26%) and low seepage fluxes will result in continuous Hg release over centuries requiring long-term groundwater remediation. Results of soluble Hg speciation suggest that filtering materials should be adapted to ionic Hg species, e.g. specific resins or amalgamating metal alloys.

[Meningoradiculitis caused by herpes simplex virus type 2]. / Meningoradiculitis door herpes-simplexvirus type 2.

A 24-year-old immune-competent woman was admitted to hospital with a three-day history of fever and headache. On examination bilateral facial nerve palsy, lumbosacral radicular pain, reduced sacral sensibility and urinary retention were found. Open perianal lesions were suspect for genital herpes. The symptoms were compatible with a meningoradiculitis including a sacral polyradiculitis. On testing, cerebrospinal fluid was found to be abnormal with a lymphocytic cell reaction. Polymerase chain reaction (PCR) of cerebrospinal fluid and of the perianal lesions was positive for herpes simplex virus type 2 (HSV-2). An MRI scan showed colouration of part of the cauda equina. The patient was treated by intravenous injections of acyclovir 10 mg/kg t.i.d. for 21 days, after which she completely recovered. HSV-2 infection of the nervous system can cause lymphocytic, and sometimes recurrent meningitis as well as sacral polyradiculitis. It may also occur without any symptomatic genital herpes infection. A positive result from a PCR test of the cerebrospinal fluid confirms this diagnosis. Treatment with acyclovir should be started as soon as possible.

Ixodes ticks belonging to the Ixodes ricinus complex encode a family of anticomplement proteins.

The alternative pathway of complement is an important innate defence against pathogens including ticks. This component of the immune system has selected for pathogens that have evolved countermeasures. Recently, a salivary protein able to inhibit the alternative pathway was cloned from the American tick Ixodes scapularis (Valenzuela et al., 2000; J. Biol. Chem. 275, 18717-18723). Here, we isolated two different sequences, similar to Isac, from the transcriptome of I. ricinus salivary glands. Expression of these sequences revealed that they both encode secreted proteins able to inhibit the complement alternative pathway. These proteins, called I. ricinus anticomplement (IRAC) protein I and II, are coexpressed constitutively in I. ricinus salivary glands and are upregulated during blood feeding. Also, we demonstrated that they are the products of different genes and not of alleles of the same locus. Finally, phylogenetic analyses demonstrate that ticks belonging to the Ixodes ricinus complex encode a family of relatively small anticomplement molecules undergoing diversification by positive Darwinian selection.

Canine intraneural perineurioma.

A 6-year-old castrated German Shepherd Dog was presented with a 6-month history of progressive, nonpainful, left pelvic limb paresis. Magnetic resonance imaging revealed atrophy of left-sided epaxial and hypaxial muscles from L5-L7 and an enlarged L5 spinal nerve. Exploratory hemi-laminectomy revealed focally and cylindrically thickened L5 and L6 nerve roots. Histologic evaluation of a surgical biopsy specimen from the L6 dorsal nerve root, and the L5 nerve roots after later amputation revealed distended hypercellular fascicles. This distension was due to widely separated axons surrounded by concentric lamellations formed by neoplastic perineurial cells and their processes. These pseudo-onion bulbs were separated from each other by a basophilic myxoid stroma. The perineurioma cell processes were immunonegative for S-100 (alpha and beta chains) and collagen IV, but were immunoreactive for laminin. The central axons were also immunoreactive for NF-200 and S-100. The proliferative index of the perineurioma cells, as determined by MIB-1 immunoreactivity, was about 3%. Ultrastructurally, the widely separated, interdigitating perineurioma cell processes were connected by desmosomal-like junctional complexes to form continuous circles. Their processes were covered by a discontinuous basal lamina. Each centrally placed axon was normally, thinly, or completely unmyelinated and was surrounded by a normal Schwann cell. These morphologic and immunologic features distinguish this lesion from hypertrophic neuropathy and were consistent with intraneural perineurioma.

Expression of receptor tyrosine kinases VEGFR-1 (FLT-1), VEGFR-2 (KDR), EGFR-1, PDGFRalpha and c-Met in canine primary brain tumours.

Inhibition of tumour growth and angiogenesis by targeting key growth factor receptors is a promising therapeutic strategy for central nervous system tumours. Characterization of these growth factor receptors in canine primary brain tumours has not been done. Using quantitative real-time TaqMan polymerase chain reaction (PCR), we evaluated the expression of messenger RNA (mRNA) for five tyrosine kinase growth factor receptors (vascular endothelial growth factor receptor [VEGFR]-1, VEGFR-2, endothelial growth factor receptor [EGFR]-1, platelet-derived growth factor receptor a [PDGFRa], and c-Met) relative to normal cerebral cortex in 66 spontaneous canine primary brain tumours. Increased expression of VEGFR-1 and VEGFR-2 mRNA was greatest in grade IV astrocytomas (glioblastoma multiforme) and grade III (anaplastic) oligodendrogliomas. EGFR-1 mRNA expression was more consistently increased than the other receptors in all tumour types, while increased PDGFRa mRNA expression was mostly restricted to oligodendrogliomas. The similarities in increased expression of these tyrosine kinase growth factor receptors in these canine tumours, as compared to data from their human counterparts, suggest that common molecular mechanisms may be present.