Austral journal of veterinary sciences, Sep 1, 2017
An adult water chevrotain was euthanized due to severe non-responsive pododermatitis. Incidentall... more An adult water chevrotain was euthanized due to severe non-responsive pododermatitis. Incidentally, multiple to coalescing cholesterol granulomas were identified within the right diencephalon, characterized by the presence of foamy macrophages and cholesterol clefts consistent with encephalic xanthomas. No clinical signs or predisposing conditions associated with this finding were identified. This is the first known report of encephalic xanthomas in this species.
The transmissible spongiform encephalopathies (TSEs) or prion diseases of animals are characteris... more The transmissible spongiform encephalopathies (TSEs) or prion diseases of animals are characterised by CNS spongiform change, gliosis and the accumulation of disease-associated forms of prion protein (PrP(d)). Particularly in ruminant prion diseases, a wide range of morphological types of PrP(d) depositions are found in association with neurons and glia. When light microscopic patterns of PrP(d) accumulations are correlated with sub-cellular structure, intracellular PrP(d) co-localises with lysosomes while non-intracellular PrP(d) accumulation co-localises with cell membranes and the extracellular space. Intracellular lysosomal PrP(d) is N-terminally truncated, but the site at which the PrP(d) molecule is cleaved depends on strain and cell type. Different PrP(d) cleavage sites are found for different cells infected with the same agent indicating that not all PrP(d) conformers code for different prion strains. Non-intracellular PrP(d) is full-length and is mainly found on plasma-lemmas of neuronal perikarya and dendrites and glia where it may be associated with scrapie-specific membrane pathology. These membrane changes appear to involve a redirection of the predominant axonal trafficking of normal cellular PrP and an altered endocytosis of PrP(d). PrP(d) is poorly excised from membranes, probably due to increased stabilisation on the membrane of PrP(d) complexed with other membrane ligands. PrP(d) on plasma-lemmas may also be transferred to other cells or released to the extracellular space. It is widely assumed that PrP(d) accumulations cause neurodegenerative changes that lead to clinical disease. However, when different animal prion diseases are considered, neurological deficits do not correlate well with any morphological type of PrP(d) accumulation or perturbation of PrP(d) trafficking. Non-PrP(d)-associated neurodegenerative changes in TSEs include vacuolation, tubulovesicular bodies and terminal axonal degeneration. The last of these correlates well with early neurological disease in mice, but such changes are absent from large animal prion disease. Thus, the proximate cause of clinical disease in animal prion disease is uncertain, but may not involve PrP(d).
Neuropathology and Applied Neurobiology, Jul 13, 2011
(2011) Neuropathology and Applied Neurobiology 37, 484-499 Neuropathological changes correlate te... more (2011) Neuropathology and Applied Neurobiology 37, 484-499 Neuropathological changes correlate temporally but not spatially with selected neuromodulatory responses in natural scrapie Aim: Neuropathological changes classically associated with sheep scrapie do not always correlate with clinical disease. We aimed to determine if selected neuromodulatory responses were altered during the course of the infection as it has been described in Creutzfeldt-Jakob disease and experimental bovine spongiform encephalopathy. Methods: Hemi-brains from healthy sheep and natural scrapie cases at two stages of infection were examined for biochemical alterations related to the expression of type I metabotropic glutamatergic receptors (mGluR1) and type I adenosine receptors I (A1R), and of selected downstream intermediate signalling targets. Immunohistochemistry for different scrapierelated neuropathological changes was performed in the contralateral hemi-brains. Results: PrP d deposition, spongiform change, astrocytosis and parvalbumin expression were significantly altered in brains from clinically affected sheep compared with preclinical cases and negative controls; the latter also showed significantly higher immunoreactivity for synaptophysin than clinical cases. Between clinically affected and healthy sheep, no differences were found in the protein levels of mGluR 1, while phospholipase Cb1 expression in terminally ill sheep was increased in some brain areas but decreased in others. Adenyl cyclase 1 and A1R levels were significantly lower in various brain areas of affected sheep. No abnormal biochemical expression levels of these markers were found in preclinically infected sheep. Conclusions: These findings point towards an involvement of mGluR1 and A1R downstream pathways in natural scrapie. While classical prion disease lesions and neuromodulatory responses converge in some affected regions, they do not do so in others suggesting that there are independent regulatory factors for distinct degenerative and neuroprotective responses.
Journal of Veterinary Internal Medicine, Feb 4, 2016
Background: In children, frequent congenital malformations with concomitant agenesis of the corpu... more Background: In children, frequent congenital malformations with concomitant agenesis of the corpus callosum are diagnosed by neuroimaging in association with other cerebral malformations, including interhemispheric cysts and ventriculomegaly. Similar studies providing full characterization of brain defects by in vivo magnetic resonance imaging (MRI), and correlations with the pertinent anatomic pathologic examinations are absent in veterinary medicine. Hypothesis/Objectives: Congenital brain defects underlie the neurologic signs observed in Toyger cats selectively bred for a short ear phenotype. Animals: Using proper pedigree analysis and genetic evaluations, 20 related Oriental-derived crossbred Toyger cats were evaluated. Seven clinically healthy (carrier) cats and 13 clinically affected cats that had neurologic signs, short ear phenotype and concomitant complex brain anomalies were studied. Methods: Complete physical and neurologic examinations and MRI were performed in all clinically healthy and affected cats. Postmortem and histopathologic examinations were performed in 8 affected cats and 5 healthy cats. Results: Neurologic and MRI investigations confirmed 13 clinically affected cats with structural brain abnormalities. Ventriculomegaly with frequent concomitant supratentorial interhemispheric, communicating ventricular type-1b cysts and multiple midline and callosal malformations were detected in all cats displaying neurologic signs. Genetic analysis confirmed autosomal recessive mode of inheritance with no chromosomal abnormalities. Conclusions and Clinical Importance: Neuroanatomic dissections and histopathology were helpful for evaluation of abnormalities in midline brain structures, and for the full characterization of cysts. However, MRI was more sensitive for detection of small cysts. In this feline model, MRI diagnosis had extremely good correlation with pathologic abnormalities noted in the subset of animals that were examined by both modalities.
Acute intoxication with organophosphates (OPs) can trigger status epilepticus followed by persist... more Acute intoxication with organophosphates (OPs) can trigger status epilepticus followed by persistent cognitive impairment and/or electroencephalographic abnormalities. Neuroinflammation is widely posited to influence these persistent neurological consequences. However, testing this hypothesis has been challenging, in part because traditional biometrics preclude longitudinal measures of neuroinflammation within the same animal. Therefore, we evaluated the performance of noninvasive positron emission tomography (PET), using the translocator protein (TSPO) radioligand [ 18 F]PBR111 against classic histopathologic measures of neuroinflammation in a preclinical model of acute intoxication with the OP diisopropylfluorophosphate (DFP). Adult male Sprague Dawley rats administered pyridostigmine bromide (0.1 mg/kg, im) 30 min prior to administration of DFP (4 mg/kg, sc), atropine sulfate (2 mg/kg, im) and 2-pralidoxime (25 mg/kg, im) exhibited moderate-to-severe seizure behavior. TSPO PET performed prior to DFP exposure and at 3, 7, 14, 21, and 28 days postexposure revealed distinct lesions, as defined by increased standardized uptake values (SUV). Increased SUV showed high spatial correspondence to immunohistochemical evidence of neuroinflammation, which was corroborated by cytokine gene and protein expression. Regional SUV metrics varied spatiotemporally with days postexposure and correlated with the degree of neuroinflammation detected immunohistochemically. Furthermore, SUV metrics were highly correlated with seizure severity, suggesting that early termination of OP-induced seizures may be critical for attenuating subsequent neuroinflammatory responses. Normalization of SUV values to a cerebellar reference region improved correlations to all outcome measures and seizure severity. Collectively, these results establish TSPO PET using [ 18 F]PBR111 as a robust, noninvasive tool for longitudinal monitoring of neuroinflammation following acute OP intoxication.
Late onset of hereditary cerebellar cortical abiotrophy has been described in a large variety of ... more Late onset of hereditary cerebellar cortical abiotrophy has been described in a large variety of canine breeds. In some reported conditions, the cerebellar lesion is combined with degeneration of other systems. Here we describe a new hereditary cerebellar cortical degeneration in eight adult American Staffordshire and Pit Bull Terriers. The neuronal degeneration in these animals not only affects Purkinje cells of the cerebellum but also certain thalamic nuclei. In addition, nerve cell loss appears to be associated with a lysosomal storage disease, which is restricted to the affected cell populations. The stored material was histologically and ultrastructurally identified as fluorescent lipopigment. Since animals were euthanized at various stages of the disease, it could be shown that lysosomal storage preceded neuronal loss. Selective involvement of restricted neuronal populations is highly unusual in ceroid lipofuscinoses. It remains to be determined if the present neurodegenerative disease is caused by a primary or secondary neuronal ceroid lipofuscinosis.
Similar to organophosphate (OP) nerve agents, diisopropylfluorophosphate (DFP) rapidly and irreve... more Similar to organophosphate (OP) nerve agents, diisopropylfluorophosphate (DFP) rapidly and irreversibly inhibits acetylcholinesterase, leading to convulsions that can progress to status epilepticus (SE). However, in contrast to the OP nerve agents, the long-term consequences of DFP-induced SE are not well known. Thus, we characterized the spatiotemporal profile of neuropathology during the first 2 months following acute DFP intoxication. Adult, male Sprague Dawley rats administered pyridostigmine bromide (0.1 mg/kg, im) 30 min prior to successive administration of DFP (4 mg/kg, sc), atropine sulfate (2 mg/kg, im), and 2-pralidoxime (25 mg/kg, im), exhibited moderate-to-severe seizure behavior, yet survived until euthanized at 0.5 to 60 days post exposure. Analyses of brains and hearts stained with hematoxylin-eosin, or of brains immunostained for neuronal nuclei (NeuN), glial fibrillary acidic protein (GFAP), or ionized binding adapter molecule 1 (IBA1), revealed progressive neuronal cell death, neuroinflammation, and tissue remodeling across limbic brain regions and the cerebral cortex, with no detectable pathology in the cerebellum or the heart. The lesion type and progression varied according to brain region and time after exposure. Across multiple brain regions, neuronal necrosis peaked after the first week, and neuroinflammation persisted at least 2 months after intoxication. Notably, mineralization was observed at later times in the thalamus, and to a more limited extent, in the hippocampus. Lesion severity was influenced by the initial seizure severity, and spontaneous recurrent seizures were associated with more severe brain damage. These findings parallel descriptions of neuropathology in preclinical models of acute intoxication with OP nerve agents, and other seizurogenic chemicals, suggesting conserved mechanisms of pathology downstream of chemical-induced SE.
A tumor located in the optic nerve extended through the optic chiasm, involving the hypophysis an... more A tumor located in the optic nerve extended through the optic chiasm, involving the hypophysis and the hypothalamic area in a 3.5-year-old male Boxer dog. It showed a biphasic pattern in which numerous highly fibrillated, well-differentiated pilocytic areas were intermingled with pleomorphic, microcystic tumor tissue. Immunohistochemical analysis of the tumor revealed that most of the neoplastic cells were immunoreactive for S-100 protein, with less intensity for glial fibrillary acidic protein (GFAP) and vimentin. A diagnosis of anaplastic astrocytoma was made on the basis of the histopathologic findings and immunohistochemical results. Moreover, there were similarities with the malignant variant of pilocytic astrocytoma described in human adults as an optic chiasmatic-hypothalamic glioma.
Interest in the proper neuropathological and molecular characterization of bovine spongiform ence... more Interest in the proper neuropathological and molecular characterization of bovine spongiform encephalopathy (BSE) has increased since asymptomatic and atypical cases were detected in the cattle population by active disease surveillance. In this respect we investigated a total of 95 conWrmed BSE cases originating from diVerent active and passive surveillance categories (clinical suspects, emergency-slaughter, fallen stock and routinely slaughter) in Switzerland for their neuropathological and molecular phenotype. We looked for measurable diVerences between these categories in lesion proWle, severity of spongiform change, degree of astrocytosis as well as immunohistochemical and molecular patterns of the disease-associated isoform of the prion protein (PrP d) in the caudal brainstem. Our results indicate signiWcantly higher intensities of spongiform change in clinically aVected compared to asymptomatic BSE cases. Similar eVects were in trend observed for the intensities of PrP d deposition and astrocytosis, whereas the frequencies of morphological PrP d types and the molecular patterns in Western immunoblot were not diVerent. Importantly, none of the animals included in this study revealed features of atypical BSE. Taken together, this study suggests that both clinically aVected as well as asymptomatic Swiss BSE cases in cattle share the neuropathological and molecular phenotype of classical BSE and that asymptomatic classical BSE cases are at a pre-clinical stage of the disease rather than representing a true sub-clinical form of BSE.
Acute intoxication with organophosphates (OPs) can trigger seizures that progress to status epile... more Acute intoxication with organophosphates (OPs) can trigger seizures that progress to status epilepticus, and survivors often exhibit chronic neuropathology, cognitive impairment, affective disorders, and/or electroencephalographic abnormalities. Understanding how acute injury transitions to persistent neurological sequelae is critical to developing medical countermeasures for mitigating damage following OP-induced seizures. Here, we used in vivo magnetic resonance imaging (MRI) to monitor the spatiotemporal patterns of neuropathology for 1 month after acute intoxication with diisopropylfluorophosphate (DFP). Adult male Sprague Dawley rats administered pyridostigmine bromide (0.1 mg/kg, im) 30 min prior to successive administration of DFP (4 mg/kg, sc), atropine sulfate (2 mg/kg, im), and 2-pralidoxime (25 mg/kg, im) exhibited moderate-to-severe seizure behavior. T2-weighted and diffusion-weighted MR imaging prior to DFP exposure and at 3, 7, 14, 21, or 28 days postexposure revealed prominent lesions, tissue atrophy, and ventricular enlargement in discrete brain regions. Lesions varied in intensity and/or extent over time, with the overall magnitude of injury strongly influenced by seizure severity. Importantly, lesions detected by MRI correlated spatially and temporally with histological evidence of brain pathology. Analysis of histogram parameters extracted from frequency distributions of regional apparent diffusion coefficient (ADC) values identified the standard deviation and 90th percentile of the ADC as robust metrics for quantifying persistent and progressive neuropathological changes. The interanimal and interregional variations observed in lesion severity and progression, coupled with potential reinjury following spontaneous recurrent seizures, underscore the advantages of using in vivo imaging to longitudinally monitor neuropathology and, ultimately, therapeutic response, following acute OP intoxication.
The increasing specificity of novel druggable targets coupled with the complexity of emerging the... more The increasing specificity of novel druggable targets coupled with the complexity of emerging therapeutic modalities for treating human diseases has created a growing need for nonhuman primates (NHPs) as models for translational drug discovery and nonclinical safety assessment. In particular, NHPs are critical for investigating potential unexpected/undesired on-target and off-target liabilities associated with administration of candidate biotherapeutics (nucleic acids, proteins, viral gene therapy vectors, etc.) to treat nervous system disorders. Nervous system findings unique to or overrepresented in NHPs administered biomolecule-based (“biologic”) test articles include mononuclear cell infiltration in most neural tissues for all biomolecule classes as well as neuronal necrosis with glial cell proliferation in sensory ganglia for certain viral vectors. Such test article-related findings in NHPs often must be differentiated from procedural effects (e.g., local parenchymal or meningeal reactions associated with an injection site or implanted catheter to administer a test article directly into the central nervous system) or spontaneous background findings (e.g., neuronal autophagy in sensory ganglia).
Journal of Veterinary Internal Medicine, Nov 1, 2013
Background: Canine necrotizing meningoencephalitis (NME) is a fatal, noninfectious inflammatory d... more Background: Canine necrotizing meningoencephalitis (NME) is a fatal, noninfectious inflammatory disease of unknown etiology. NME has been reported only in a small number of dog breeds, which has led to the presumption that it is a breed-restricted disorder. Hypothesis/Objectives: Our objective was to describe histopathologically confirmed NME in dog breeds in which the condition has not been reported previously and to provide preliminary evidence that NME affects a wider spectrum of dog breeds than previously reported. Animals: Four dogs with NME. Methods: Archives from 3 institutions and from 1 author's (BS) collection were reviewed to identify histopathologically confirmed cases of NME in breeds in which the disease has not been reported previously. Age, sex, breed, survival from onset of clinical signs, and histopathologic findings were evaluated. Results: Necrotizing meningoencephalitis was identified in 4 small dog breeds (Papillon, Shih Tzu, Coton de Tulear, and Brussels Griffon). Median age at clinical evaluation was 2.5 years. Histopathologic abnormalities included 2 or more of the following: lymphoplasmacytic or histiocytic meningoencephalitis or encephalitis, moderate-to-severe cerebrocortical necrosis, variable involvement of other anatomic locations within the brain (cerebellum, brainstem), and absence of detectable infectious agents. Conclusions and Clinical Importance: Until now, NME has only been described in 5 small dog breeds. We document an additional 4 small breeds previously not shown to develop NME. Our cases further illustrate that NME is not a breedrestricted disorder and should be considered in the differential diagnosis for dogs with signalment and clinical signs consistent with inflammatory brain disease.
Las encelopatias espongiformes Transmisibles (ETT)son un grupop de enfermedades en las que la pro... more Las encelopatias espongiformes Transmisibles (ETT)son un grupop de enfermedades en las que la proteina prionica celular normal(PrPc) se transforma en un isoforma patogenica resistente(PrPress). Esta proteina patogenica se acumula en el sistema nervioso central (SNC)causando una degenaracion de curso cronico, progresivo y fatal. En este estudio se presentan los resultados obtenidos en el estudio inmunoquimico de tres casos de vacas diagnosticados como positivos frente a la EEB por el Laboratori de Referencia en Malalties Prionicas de Catalunya (PRIOCAT). Los resultados del Western-Blotting de estos tres animales presentaron en el obex el patron tipico de las tres bandas entre 25-35 KD. Se detecto PrP total en todas las areas analizadas y la distribucion de PrPress vario entre los animales siendo los resultados similares en todo el tronco encefalico incluido el nucleo caudado hasta la medula espinal. No obstante se observaron algunas diferencias entre estos animales
Canine distemper virus commonly infects free-ranging, terrestrial mesopredators throughout the Un... more Canine distemper virus commonly infects free-ranging, terrestrial mesopredators throughout the United States. Due to the immunosuppressive effects of the virus, concurrent opportunistic infections are also common. Among these, secondary systemic protozoal infections have been described in a number of species. We report an unusual presentation of necrotizing encephalitis associated with Sarcocystis sp in four raccoons and one skunk concurrently infected with canine distemper virus. Lesions were characterized by variably sized necrotizing cavitations composed of abundant mineral admixed with inflammatory cells and protozoa. Sarcocystis sp was confirmed via immunohistochemistry using a monoclonal antibody to Sarcocystis neurona. The pathologic changes are similar to lesions in human AIDS patients infected with Toxoplasma gondii.
Data associating quantitative viral load with severity, clinical signs and survival in equine her... more Data associating quantitative viral load with severity, clinical signs and survival in equine herpesvirus-1 myeloencephalopathy (EHM) have not been reported. To report the clinical signs, treatment, and temporal progression of viral loads in 7 horses with naturally occurring EHM and to examine the association of these factors with survival. Retrospective case series. The population included 7 horses with EHM presented to the University of California, Davis William R. Pritchard Veterinary Medical Teaching Hospital from May to September 2011. Horses were graded using a neurological grading scale. Daily quantitative PCR was performed on nasal secretions and whole blood. Treatment, survival, outcome and histopathology were reported. At presentation, one horse was neurological grade 5/5, 3 were grade 4/5 and 3 were grade 3/5. All were treated with anti-inflammatory drugs, valacyclovir and management in a sling if necessary. All were infected with equine herpesvirus-1 of DNA polymerase D7...
Austral journal of veterinary sciences, Sep 1, 2017
An adult water chevrotain was euthanized due to severe non-responsive pododermatitis. Incidentall... more An adult water chevrotain was euthanized due to severe non-responsive pododermatitis. Incidentally, multiple to coalescing cholesterol granulomas were identified within the right diencephalon, characterized by the presence of foamy macrophages and cholesterol clefts consistent with encephalic xanthomas. No clinical signs or predisposing conditions associated with this finding were identified. This is the first known report of encephalic xanthomas in this species.
The transmissible spongiform encephalopathies (TSEs) or prion diseases of animals are characteris... more The transmissible spongiform encephalopathies (TSEs) or prion diseases of animals are characterised by CNS spongiform change, gliosis and the accumulation of disease-associated forms of prion protein (PrP(d)). Particularly in ruminant prion diseases, a wide range of morphological types of PrP(d) depositions are found in association with neurons and glia. When light microscopic patterns of PrP(d) accumulations are correlated with sub-cellular structure, intracellular PrP(d) co-localises with lysosomes while non-intracellular PrP(d) accumulation co-localises with cell membranes and the extracellular space. Intracellular lysosomal PrP(d) is N-terminally truncated, but the site at which the PrP(d) molecule is cleaved depends on strain and cell type. Different PrP(d) cleavage sites are found for different cells infected with the same agent indicating that not all PrP(d) conformers code for different prion strains. Non-intracellular PrP(d) is full-length and is mainly found on plasma-lemmas of neuronal perikarya and dendrites and glia where it may be associated with scrapie-specific membrane pathology. These membrane changes appear to involve a redirection of the predominant axonal trafficking of normal cellular PrP and an altered endocytosis of PrP(d). PrP(d) is poorly excised from membranes, probably due to increased stabilisation on the membrane of PrP(d) complexed with other membrane ligands. PrP(d) on plasma-lemmas may also be transferred to other cells or released to the extracellular space. It is widely assumed that PrP(d) accumulations cause neurodegenerative changes that lead to clinical disease. However, when different animal prion diseases are considered, neurological deficits do not correlate well with any morphological type of PrP(d) accumulation or perturbation of PrP(d) trafficking. Non-PrP(d)-associated neurodegenerative changes in TSEs include vacuolation, tubulovesicular bodies and terminal axonal degeneration. The last of these correlates well with early neurological disease in mice, but such changes are absent from large animal prion disease. Thus, the proximate cause of clinical disease in animal prion disease is uncertain, but may not involve PrP(d).
Neuropathology and Applied Neurobiology, Jul 13, 2011
(2011) Neuropathology and Applied Neurobiology 37, 484-499 Neuropathological changes correlate te... more (2011) Neuropathology and Applied Neurobiology 37, 484-499 Neuropathological changes correlate temporally but not spatially with selected neuromodulatory responses in natural scrapie Aim: Neuropathological changes classically associated with sheep scrapie do not always correlate with clinical disease. We aimed to determine if selected neuromodulatory responses were altered during the course of the infection as it has been described in Creutzfeldt-Jakob disease and experimental bovine spongiform encephalopathy. Methods: Hemi-brains from healthy sheep and natural scrapie cases at two stages of infection were examined for biochemical alterations related to the expression of type I metabotropic glutamatergic receptors (mGluR1) and type I adenosine receptors I (A1R), and of selected downstream intermediate signalling targets. Immunohistochemistry for different scrapierelated neuropathological changes was performed in the contralateral hemi-brains. Results: PrP d deposition, spongiform change, astrocytosis and parvalbumin expression were significantly altered in brains from clinically affected sheep compared with preclinical cases and negative controls; the latter also showed significantly higher immunoreactivity for synaptophysin than clinical cases. Between clinically affected and healthy sheep, no differences were found in the protein levels of mGluR 1, while phospholipase Cb1 expression in terminally ill sheep was increased in some brain areas but decreased in others. Adenyl cyclase 1 and A1R levels were significantly lower in various brain areas of affected sheep. No abnormal biochemical expression levels of these markers were found in preclinically infected sheep. Conclusions: These findings point towards an involvement of mGluR1 and A1R downstream pathways in natural scrapie. While classical prion disease lesions and neuromodulatory responses converge in some affected regions, they do not do so in others suggesting that there are independent regulatory factors for distinct degenerative and neuroprotective responses.
Journal of Veterinary Internal Medicine, Feb 4, 2016
Background: In children, frequent congenital malformations with concomitant agenesis of the corpu... more Background: In children, frequent congenital malformations with concomitant agenesis of the corpus callosum are diagnosed by neuroimaging in association with other cerebral malformations, including interhemispheric cysts and ventriculomegaly. Similar studies providing full characterization of brain defects by in vivo magnetic resonance imaging (MRI), and correlations with the pertinent anatomic pathologic examinations are absent in veterinary medicine. Hypothesis/Objectives: Congenital brain defects underlie the neurologic signs observed in Toyger cats selectively bred for a short ear phenotype. Animals: Using proper pedigree analysis and genetic evaluations, 20 related Oriental-derived crossbred Toyger cats were evaluated. Seven clinically healthy (carrier) cats and 13 clinically affected cats that had neurologic signs, short ear phenotype and concomitant complex brain anomalies were studied. Methods: Complete physical and neurologic examinations and MRI were performed in all clinically healthy and affected cats. Postmortem and histopathologic examinations were performed in 8 affected cats and 5 healthy cats. Results: Neurologic and MRI investigations confirmed 13 clinically affected cats with structural brain abnormalities. Ventriculomegaly with frequent concomitant supratentorial interhemispheric, communicating ventricular type-1b cysts and multiple midline and callosal malformations were detected in all cats displaying neurologic signs. Genetic analysis confirmed autosomal recessive mode of inheritance with no chromosomal abnormalities. Conclusions and Clinical Importance: Neuroanatomic dissections and histopathology were helpful for evaluation of abnormalities in midline brain structures, and for the full characterization of cysts. However, MRI was more sensitive for detection of small cysts. In this feline model, MRI diagnosis had extremely good correlation with pathologic abnormalities noted in the subset of animals that were examined by both modalities.
Acute intoxication with organophosphates (OPs) can trigger status epilepticus followed by persist... more Acute intoxication with organophosphates (OPs) can trigger status epilepticus followed by persistent cognitive impairment and/or electroencephalographic abnormalities. Neuroinflammation is widely posited to influence these persistent neurological consequences. However, testing this hypothesis has been challenging, in part because traditional biometrics preclude longitudinal measures of neuroinflammation within the same animal. Therefore, we evaluated the performance of noninvasive positron emission tomography (PET), using the translocator protein (TSPO) radioligand [ 18 F]PBR111 against classic histopathologic measures of neuroinflammation in a preclinical model of acute intoxication with the OP diisopropylfluorophosphate (DFP). Adult male Sprague Dawley rats administered pyridostigmine bromide (0.1 mg/kg, im) 30 min prior to administration of DFP (4 mg/kg, sc), atropine sulfate (2 mg/kg, im) and 2-pralidoxime (25 mg/kg, im) exhibited moderate-to-severe seizure behavior. TSPO PET performed prior to DFP exposure and at 3, 7, 14, 21, and 28 days postexposure revealed distinct lesions, as defined by increased standardized uptake values (SUV). Increased SUV showed high spatial correspondence to immunohistochemical evidence of neuroinflammation, which was corroborated by cytokine gene and protein expression. Regional SUV metrics varied spatiotemporally with days postexposure and correlated with the degree of neuroinflammation detected immunohistochemically. Furthermore, SUV metrics were highly correlated with seizure severity, suggesting that early termination of OP-induced seizures may be critical for attenuating subsequent neuroinflammatory responses. Normalization of SUV values to a cerebellar reference region improved correlations to all outcome measures and seizure severity. Collectively, these results establish TSPO PET using [ 18 F]PBR111 as a robust, noninvasive tool for longitudinal monitoring of neuroinflammation following acute OP intoxication.
Late onset of hereditary cerebellar cortical abiotrophy has been described in a large variety of ... more Late onset of hereditary cerebellar cortical abiotrophy has been described in a large variety of canine breeds. In some reported conditions, the cerebellar lesion is combined with degeneration of other systems. Here we describe a new hereditary cerebellar cortical degeneration in eight adult American Staffordshire and Pit Bull Terriers. The neuronal degeneration in these animals not only affects Purkinje cells of the cerebellum but also certain thalamic nuclei. In addition, nerve cell loss appears to be associated with a lysosomal storage disease, which is restricted to the affected cell populations. The stored material was histologically and ultrastructurally identified as fluorescent lipopigment. Since animals were euthanized at various stages of the disease, it could be shown that lysosomal storage preceded neuronal loss. Selective involvement of restricted neuronal populations is highly unusual in ceroid lipofuscinoses. It remains to be determined if the present neurodegenerative disease is caused by a primary or secondary neuronal ceroid lipofuscinosis.
Similar to organophosphate (OP) nerve agents, diisopropylfluorophosphate (DFP) rapidly and irreve... more Similar to organophosphate (OP) nerve agents, diisopropylfluorophosphate (DFP) rapidly and irreversibly inhibits acetylcholinesterase, leading to convulsions that can progress to status epilepticus (SE). However, in contrast to the OP nerve agents, the long-term consequences of DFP-induced SE are not well known. Thus, we characterized the spatiotemporal profile of neuropathology during the first 2 months following acute DFP intoxication. Adult, male Sprague Dawley rats administered pyridostigmine bromide (0.1 mg/kg, im) 30 min prior to successive administration of DFP (4 mg/kg, sc), atropine sulfate (2 mg/kg, im), and 2-pralidoxime (25 mg/kg, im), exhibited moderate-to-severe seizure behavior, yet survived until euthanized at 0.5 to 60 days post exposure. Analyses of brains and hearts stained with hematoxylin-eosin, or of brains immunostained for neuronal nuclei (NeuN), glial fibrillary acidic protein (GFAP), or ionized binding adapter molecule 1 (IBA1), revealed progressive neuronal cell death, neuroinflammation, and tissue remodeling across limbic brain regions and the cerebral cortex, with no detectable pathology in the cerebellum or the heart. The lesion type and progression varied according to brain region and time after exposure. Across multiple brain regions, neuronal necrosis peaked after the first week, and neuroinflammation persisted at least 2 months after intoxication. Notably, mineralization was observed at later times in the thalamus, and to a more limited extent, in the hippocampus. Lesion severity was influenced by the initial seizure severity, and spontaneous recurrent seizures were associated with more severe brain damage. These findings parallel descriptions of neuropathology in preclinical models of acute intoxication with OP nerve agents, and other seizurogenic chemicals, suggesting conserved mechanisms of pathology downstream of chemical-induced SE.
A tumor located in the optic nerve extended through the optic chiasm, involving the hypophysis an... more A tumor located in the optic nerve extended through the optic chiasm, involving the hypophysis and the hypothalamic area in a 3.5-year-old male Boxer dog. It showed a biphasic pattern in which numerous highly fibrillated, well-differentiated pilocytic areas were intermingled with pleomorphic, microcystic tumor tissue. Immunohistochemical analysis of the tumor revealed that most of the neoplastic cells were immunoreactive for S-100 protein, with less intensity for glial fibrillary acidic protein (GFAP) and vimentin. A diagnosis of anaplastic astrocytoma was made on the basis of the histopathologic findings and immunohistochemical results. Moreover, there were similarities with the malignant variant of pilocytic astrocytoma described in human adults as an optic chiasmatic-hypothalamic glioma.
Interest in the proper neuropathological and molecular characterization of bovine spongiform ence... more Interest in the proper neuropathological and molecular characterization of bovine spongiform encephalopathy (BSE) has increased since asymptomatic and atypical cases were detected in the cattle population by active disease surveillance. In this respect we investigated a total of 95 conWrmed BSE cases originating from diVerent active and passive surveillance categories (clinical suspects, emergency-slaughter, fallen stock and routinely slaughter) in Switzerland for their neuropathological and molecular phenotype. We looked for measurable diVerences between these categories in lesion proWle, severity of spongiform change, degree of astrocytosis as well as immunohistochemical and molecular patterns of the disease-associated isoform of the prion protein (PrP d) in the caudal brainstem. Our results indicate signiWcantly higher intensities of spongiform change in clinically aVected compared to asymptomatic BSE cases. Similar eVects were in trend observed for the intensities of PrP d deposition and astrocytosis, whereas the frequencies of morphological PrP d types and the molecular patterns in Western immunoblot were not diVerent. Importantly, none of the animals included in this study revealed features of atypical BSE. Taken together, this study suggests that both clinically aVected as well as asymptomatic Swiss BSE cases in cattle share the neuropathological and molecular phenotype of classical BSE and that asymptomatic classical BSE cases are at a pre-clinical stage of the disease rather than representing a true sub-clinical form of BSE.
Acute intoxication with organophosphates (OPs) can trigger seizures that progress to status epile... more Acute intoxication with organophosphates (OPs) can trigger seizures that progress to status epilepticus, and survivors often exhibit chronic neuropathology, cognitive impairment, affective disorders, and/or electroencephalographic abnormalities. Understanding how acute injury transitions to persistent neurological sequelae is critical to developing medical countermeasures for mitigating damage following OP-induced seizures. Here, we used in vivo magnetic resonance imaging (MRI) to monitor the spatiotemporal patterns of neuropathology for 1 month after acute intoxication with diisopropylfluorophosphate (DFP). Adult male Sprague Dawley rats administered pyridostigmine bromide (0.1 mg/kg, im) 30 min prior to successive administration of DFP (4 mg/kg, sc), atropine sulfate (2 mg/kg, im), and 2-pralidoxime (25 mg/kg, im) exhibited moderate-to-severe seizure behavior. T2-weighted and diffusion-weighted MR imaging prior to DFP exposure and at 3, 7, 14, 21, or 28 days postexposure revealed prominent lesions, tissue atrophy, and ventricular enlargement in discrete brain regions. Lesions varied in intensity and/or extent over time, with the overall magnitude of injury strongly influenced by seizure severity. Importantly, lesions detected by MRI correlated spatially and temporally with histological evidence of brain pathology. Analysis of histogram parameters extracted from frequency distributions of regional apparent diffusion coefficient (ADC) values identified the standard deviation and 90th percentile of the ADC as robust metrics for quantifying persistent and progressive neuropathological changes. The interanimal and interregional variations observed in lesion severity and progression, coupled with potential reinjury following spontaneous recurrent seizures, underscore the advantages of using in vivo imaging to longitudinally monitor neuropathology and, ultimately, therapeutic response, following acute OP intoxication.
The increasing specificity of novel druggable targets coupled with the complexity of emerging the... more The increasing specificity of novel druggable targets coupled with the complexity of emerging therapeutic modalities for treating human diseases has created a growing need for nonhuman primates (NHPs) as models for translational drug discovery and nonclinical safety assessment. In particular, NHPs are critical for investigating potential unexpected/undesired on-target and off-target liabilities associated with administration of candidate biotherapeutics (nucleic acids, proteins, viral gene therapy vectors, etc.) to treat nervous system disorders. Nervous system findings unique to or overrepresented in NHPs administered biomolecule-based (“biologic”) test articles include mononuclear cell infiltration in most neural tissues for all biomolecule classes as well as neuronal necrosis with glial cell proliferation in sensory ganglia for certain viral vectors. Such test article-related findings in NHPs often must be differentiated from procedural effects (e.g., local parenchymal or meningeal reactions associated with an injection site or implanted catheter to administer a test article directly into the central nervous system) or spontaneous background findings (e.g., neuronal autophagy in sensory ganglia).
Journal of Veterinary Internal Medicine, Nov 1, 2013
Background: Canine necrotizing meningoencephalitis (NME) is a fatal, noninfectious inflammatory d... more Background: Canine necrotizing meningoencephalitis (NME) is a fatal, noninfectious inflammatory disease of unknown etiology. NME has been reported only in a small number of dog breeds, which has led to the presumption that it is a breed-restricted disorder. Hypothesis/Objectives: Our objective was to describe histopathologically confirmed NME in dog breeds in which the condition has not been reported previously and to provide preliminary evidence that NME affects a wider spectrum of dog breeds than previously reported. Animals: Four dogs with NME. Methods: Archives from 3 institutions and from 1 author's (BS) collection were reviewed to identify histopathologically confirmed cases of NME in breeds in which the disease has not been reported previously. Age, sex, breed, survival from onset of clinical signs, and histopathologic findings were evaluated. Results: Necrotizing meningoencephalitis was identified in 4 small dog breeds (Papillon, Shih Tzu, Coton de Tulear, and Brussels Griffon). Median age at clinical evaluation was 2.5 years. Histopathologic abnormalities included 2 or more of the following: lymphoplasmacytic or histiocytic meningoencephalitis or encephalitis, moderate-to-severe cerebrocortical necrosis, variable involvement of other anatomic locations within the brain (cerebellum, brainstem), and absence of detectable infectious agents. Conclusions and Clinical Importance: Until now, NME has only been described in 5 small dog breeds. We document an additional 4 small breeds previously not shown to develop NME. Our cases further illustrate that NME is not a breedrestricted disorder and should be considered in the differential diagnosis for dogs with signalment and clinical signs consistent with inflammatory brain disease.
Las encelopatias espongiformes Transmisibles (ETT)son un grupop de enfermedades en las que la pro... more Las encelopatias espongiformes Transmisibles (ETT)son un grupop de enfermedades en las que la proteina prionica celular normal(PrPc) se transforma en un isoforma patogenica resistente(PrPress). Esta proteina patogenica se acumula en el sistema nervioso central (SNC)causando una degenaracion de curso cronico, progresivo y fatal. En este estudio se presentan los resultados obtenidos en el estudio inmunoquimico de tres casos de vacas diagnosticados como positivos frente a la EEB por el Laboratori de Referencia en Malalties Prionicas de Catalunya (PRIOCAT). Los resultados del Western-Blotting de estos tres animales presentaron en el obex el patron tipico de las tres bandas entre 25-35 KD. Se detecto PrP total en todas las areas analizadas y la distribucion de PrPress vario entre los animales siendo los resultados similares en todo el tronco encefalico incluido el nucleo caudado hasta la medula espinal. No obstante se observaron algunas diferencias entre estos animales
Canine distemper virus commonly infects free-ranging, terrestrial mesopredators throughout the Un... more Canine distemper virus commonly infects free-ranging, terrestrial mesopredators throughout the United States. Due to the immunosuppressive effects of the virus, concurrent opportunistic infections are also common. Among these, secondary systemic protozoal infections have been described in a number of species. We report an unusual presentation of necrotizing encephalitis associated with Sarcocystis sp in four raccoons and one skunk concurrently infected with canine distemper virus. Lesions were characterized by variably sized necrotizing cavitations composed of abundant mineral admixed with inflammatory cells and protozoa. Sarcocystis sp was confirmed via immunohistochemistry using a monoclonal antibody to Sarcocystis neurona. The pathologic changes are similar to lesions in human AIDS patients infected with Toxoplasma gondii.
Data associating quantitative viral load with severity, clinical signs and survival in equine her... more Data associating quantitative viral load with severity, clinical signs and survival in equine herpesvirus-1 myeloencephalopathy (EHM) have not been reported. To report the clinical signs, treatment, and temporal progression of viral loads in 7 horses with naturally occurring EHM and to examine the association of these factors with survival. Retrospective case series. The population included 7 horses with EHM presented to the University of California, Davis William R. Pritchard Veterinary Medical Teaching Hospital from May to September 2011. Horses were graded using a neurological grading scale. Daily quantitative PCR was performed on nasal secretions and whole blood. Treatment, survival, outcome and histopathology were reported. At presentation, one horse was neurological grade 5/5, 3 were grade 4/5 and 3 were grade 3/5. All were treated with anti-inflammatory drugs, valacyclovir and management in a sling if necessary. All were infected with equine herpesvirus-1 of DNA polymerase D7...
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