Naoaki Matsuki

Positive reactions to common allergens in 42 atopic dogs in Japan.

Clinically important allergens for the diagnosis and treatment of atopic dermatitis vary geographically. In order to identify the most prevalent allergens in atopic dogs in Japan, 42 dogs with a clinical diagnosis of atopy were tested using both in vivo (intradermal skin test (IDST)) and in vitro (antigen-specific IgE assay) allergy tests. Allergens used for IDST included 26 allergen extracts from eight allergen groups: trees, weeds, grasses, house dust mites (HDM), molds, foods, epithelia, and arthropods. Immunodot assay was used to measure antigen-specific IgE against 24 allergens from these eight groups and against fish such as cod and sole. In the 42 dogs, the most common positive allergen reaction was to HDM on both IDST (29/42 dogs or 69%) and in vitro testing (23/42 or 54.8%). The second most frequent positive allergen reaction was to Japanese cedar pollen (21/42 or 50.0% for IDST and 7/42 or 16.7% for in vitro testing). In both tests, less than 20% of dogs had positive reactions to molds or foods. Positive reactions to cat epithelia were frequently found on IDST, but rarely found on in vitro testing. Agreement between the two tests was found in 26 instances: HDM (21 dogs), Japanese cedar pollen (five dogs) and wheat (one dog). In this study, the two most common allergens involved in atopic dermatitis in dogs in Japan were HDM and Japanese cedar pollen.

Hepatic changes in the acute phase of streptozotocin (SZ)-induced diabetes in mice.

We have reported the streptozotocin (SZ)-induced hepatic lesions in the subacute phase (4 to 12 weeks after the treatment), which are characterized by appearance of oncocytic hepatocytes, cytomegalic hepatocytes and bile duct hyperplasia. In this study, we focused on the acute phase (6 to 48 hours after the treatment) of the SZ-induced hepatic lesions of mice to clarify the onset of the hepatic alterations, especially before the induction of hyperglycemia. Livers were taken from 8-week-old Crj:CD-1 (ICR) male mice at 6, 12, 24, 36 and 48 hours after the 200 mg/kg b.w. of SZ-injection. SZ-induced hyperglycemia was noted at 36 and 48 hours after the treatment, but the hepatic changes including lipid peroxidation, mitochondrial swelling, peroxisome proliferation and inhibition of hepatocyte proliferation occurred before the elevation of the serum glucose levels. The present findings indicate the direct effects of SZ on hepatocytes rather than the secondary effects of diabetes, and certain correlations between the hepatocytic changes in the acute phase and those in the subacute one. In addition, ulcer and submucosal edema of the gallbladder were observed at 36 or 48 hours after the SZ-treatment, which can be a novel finding in SZ-treated animal.

Sandhoff disease in a golden retriever dog

A golden retriever dog is described with total hexosaminid ase deficiency and raised GM2-ganglioside in CSF. The animal represents a model for human Sandhoff disease.

A familial spontaneous epileptic feline strain: A novel model of idiopathic/genetic epilepsy

A spontaneous epileptic model of cats has not been described previously. Recently, we identified familial epileptic cats and investigated their clinical features. These epileptic cats are healthy except for the presence of recurrent seizures that are typically a focal limbic seizure with secondary generalization. Furthermore, generalized seizures were induced by vestibular stimulation in some cats. This spontaneous epileptic cat strain may be a valuable model for idiopathic/genetic epilepsy.

Glial fibrillary acidic protein (GFAP) and anti-GFAP autoantibody in canine necrotising meningoencephalitis

To establish clinical markers for canine necrotising meningoencephalitis (nme) and to elucidate its pathogenesis, glial fibrillary acidic protein (gfap) and anti-gfap autoantibodies were measured in the cerebrospinal fluid (csf) of 32 dogs with nme, 23 dogs with other inflammatory central nervous system (cns) diseases, 27 dogs with miscellaneous cns diseases and 25 healthy dogs, including five pugs. The dogs with nme had the highest levels of anti-gfap autoantibodies. The diagnostic sensitivity and specificity of anti-gfap autoantibodies for nme were 91 per cent and 73 per cent, respectively. Some of the dogs with nme and the healthy pugs, had high csf concentrations of gfap, suggesting a breed-specific fragility of astrocytes. The leakage of gfap and the development of autoimmunity may be key to understanding the pathogenesis of nme.

Laboratory Diagnosis of Canine GM2-Gangliosidosis using Blood and Cerebrospinal Fluid

In the present study, laboratory techniques were used to diagnose canine GM2-gangliosidosis using blood and cerebrospinal fluid (CSF) that can be collected noninvasively from living individuals. Lysosomal acid β-hexosaminidase (Hex) was measured spectrofluorometrically using 4-methylumbelliferyl N-acetyl-β-d-glucosaminide and 4-methylumbelliferyl 7-(6-sulfo-2-acetamido-2-deoxy-β-d-glucopyranoside) as substrates. Main isoenzymes A and B of Hex in leukocytes were also analyzed using cellulose acetate membrane electrophoresis. GM2-ganglioside in CSF was detected and determined quantitatively by using thin-layer chromatography/enzyme-immunostaining method with anti-GM2-ganglioside antibody. In normal dogs, Hex activities could be determined in leukocytes, serum, and CSF, and the total activities were markedly reduced in all the enzyme sources in a dog with Sandhoff disease. Electrophoresis of a leukocyte lysate from a normal dog showed that the Hex A and Hex B were not separated distinctively with formation of a broad band, whereas there were no bands in electrophoresis of a lysate from a dog with Sandhoff disease, showing a deficiency in the total enzyme activity. GM2-ganglioside could be detected and determined quantitatively in as little as 100 μl of canine CSF. GM2-ganglioside in CSF in a dog with Sandhoff disease increased to 46 times the normal level. In conclusion, the methods in the present study are useful for diagnosis of canine GM2-gangliosidosis. These techniques enable definitive and early diagnosis of canine GM2-gangliosidosis even if tissues and organs cannot be obtained.

Effect of the extracellular matrix on pancreatic endocrine cell function and its biocompatibility in dogs

The effect of the synthetic extracellular matrix (ECM) in a diffusion chamber for a bioartificial endocrine pancreas (Bio-AEP) on pancreatic endocrine cells in vitro and its biocompatibility in dogs were investigated. Two different types of ECM were used: type I collagen treated with low antigen (type I LA), and reconstituted basement membrane matrix (Matrigel) derived from Englbreth-Holm-Swarm (EHS) mouse sarcoma. Matrigel contains growth and differentiation factors and cell adhesion molecules such as laminin, heparan sulfate proteoglycan, and entactin. Purified porcine pancreatic endocrine (PE) cells were suspended in type I LA or Matrigel and then placed into a 12-well culture plate (4 × 107 cells/ml · gel/well). The insulin accumulation from PE cells in Matrigel was significantly greater than that in type I LA (9.3 ± 3.6 mU/well vs. 2.3 ± 1.3 mU/well). When Bio-AEP with Matrigel and PE cells was implanted into the abdominal cavity of a pancreatectomized diabetic dog, the exogenous insulin requirement for maintaining normoglycemia was reduced for the first 4 weeks. However, after 6 weeks of implantation, fasting blood glucose levels suddenly increased. Laparotomy revealed encapsulated Bio-AEP with thick fibrous tissue. Following removal of the Bio-AEP from the abdominal cavity, another Bio-AEP containing type I LA and PE cells was implanted into the same dog. The exogenous insulin requirement was gradually decreased to almost half that of preim-plantation levels. Bio-AEPs containing type I LA or Matrigel, but not PE cells, were implanted into the abdominal cavities of four healthy dogs. After 4 weeks of implantation, the Bio-AEP with Matrigel was encapsulated with fibrous tissue similar to that in the diabetic dog, but the Bio-AEP with type I LA was not. These results indicate that Matrigel may be incompatible with dogs and that the type I LA is more suitable for Bio-AEP.

Magnetic resonance volumetry of the hippocampus in familial spontaneous epileptic cats

A strain of familial spontaneous epileptic cats (FSECs) with typical limbic seizures was identified in 2010. The electroencephalographic features suggested that an epileptogenic zone is present in the mesial temporal structures (i.e., amygdala and/or hippocampus). In this study, visual evaluations and quantitative analyses were performed by using 3D MR hippocampal volumetry in comparing FSECs with age-matched controls. Visual hippocampal asymmetries were seen in 8 of 14 (57.1%) FSECs. The FSEC group showed a significantly higher asymmetric ratio (4.15%) than the control group (0.99%). The smaller side of hippocampal volume (HV) (0.206 cm(3)) in FSECs was significantly smaller than the mean HV in controls (0.227 cm(3)). However, the means of left and right HVs and total HVs in FSECs showed no differences because the laterality of hippocampal atrophy was different in each individual. Therefore, since FSECs represent a true model of spontaneous epilepsy, hippocampal volumetry should be evaluated in each individual as well as in human patients. The significant asymmetry of HV suggests the potential for hippocampal atrophy in FSECs.

Electroencephalographic features of familial spontaneous epileptic cats

A feline strain of familial spontaneous epileptic cats (FSECs) with typical limbic seizures was identified in 2010, and have been maintained as a novel animal model of genetic epilepsy. In this study, we characterized the electroencephalographic (EEG) features of FSECs. On scalp EEG under sedation, FSECs showed sporadic, but comparatively frequent interictal discharges dominantly in the uni- or bilateral temporal region. Bemegride activation was performed in order to evaluate the predisposition of epileptogenicity of FSECs. The threshold doses of the first paroxysmal discharge, clinical myoclonus and generalized convulsion in FSECs were significantly lower than those in control cats. Chronic video-intracranial EEG monitoring revealed subclinical or clinical focal seizures with secondarily generalization onset from the unilateral amygdala and/or hippocampus. Clinical generalized seizures were also recorded, but we were unable to detect the onset site. The results of the present study show that FSECs resemble not only feline kindling or the kainic acid model and El mouse, but also human familial or sporadic mesial temporal lobe epilepsy. In addition, our results indicate that FSECs are a natural and valuable model of mesial temporal lobe epilepsy.

Magnetic Resonance Findings of the Corpus Callosum in Canine and Feline Lysosomal Storage Diseases

Several reports have described magnetic resonance (MR) findings in canine and feline lysosomal storage diseases such as gangliosidoses and neuronal ceroid lipofuscinosis. Although most of those studies described the signal intensities of white matter in the cerebrum, findings of the corpus callosum were not described in detail. A retrospective study was conducted on MR findings of the corpus callosum as well as the rostral commissure and the fornix in 18 cases of canine and feline lysosomal storage diseases. This included 6 Shiba Inu dogs and 2 domestic shorthair cats with GM1 gangliosidosis; 2 domestic shorthair cats, 2 familial toy poodles, and a golden retriever with GM2 gangliosidosis; and 2 border collies and 3 chihuahuas with neuronal ceroid lipofuscinoses, to determine whether changes of the corpus callosum is an imaging indicator of those diseases. The corpus callosum and the rostral commissure were difficult to recognize in all cases of juvenile-onset gangliosidoses (GM1 gangliosidosis in Shiba Inu dogs and domestic shorthair cats and GM2 gangliosidosis in domestic shorthair cats) and GM2 gangliosidosis in toy poodles with late juvenile-onset. In contrast, the corpus callosum and the rostral commissure were confirmed in cases of GM2 gangliosidosis in a golden retriever and canine neuronal ceroid lipofuscinoses with late juvenile- to early adult-onset, but were extremely thin. Abnormal findings of the corpus callosum on midline sagittal images may be a useful imaging indicator for suspecting lysosomal storage diseases, especially hypoplasia (underdevelopment) of the corpus callosum in juvenile-onset gangliosidoses.