Hiroyuki Taniyama

Monocarboxylate transporter 1 (MCT1) plays a direct role in short-chain fatty acids absorption in caprine rumen

Despite the importance of short‐chain fatty acids (SCFA) in maintaining the ruminant physiology, the mechanism of SCFA absorption is still not fully studied. The goal of this study was to elucidate the possible involvement of monocarboxylate transporter 1 (MCT1) in the mechanism of SCFA transport in the caprine rumen, and to delineate the precise cellular localization and the level of MCT1 protein along the entire caprine gastrointestinal tract. RT‐PCR revealed the presence of mRNA encoding for MCT1 in all regions of the caprine gastrointestinal tract. Quantitative Western blot analysis showed that the level of MCT1 protein was in the order of rumen ≥ reticulum > omasum > caecum > proximal colon > distal colon > abomasum > small intestine. Immunohistochemistry and immunofluorescence confocal analyses revealed widespread immunoreactive positivities for MCT1 in the caprine stomach and large intestine. Amongst the stratified squamous epithelial cells of the forestomach, MCT1 was predominantly expressed on the cell boundaries of the stratum basale and stratum spinosum. Double‐immunofluorescence confocal laser‐scanning microscopy confirmed the co‐localization of MCT1 with its ancillary protein, CD147 in the caprine gastrointestinal tract. In vivo and in vitro functional studies, under the influence of the MCT1 inhibitors, p‐chloromercuribenzoate (pCMB) and p‐chloromercuribenzoic acid (pCMBA), demonstrated significant inhibitory effect on acetate and propionate transport in the rumen. This study provides evidence, for the first time in ruminants, that MCT1 has a direct role in the transepithelial transport and efflux of the SCFA across the stratum spinosum and stratum basale of the forestomach toward the blood side.

Glial expression of Borna disease virus phosphoprotein induces behavioral and neurological abnormalities in transgenic mice

One hypothesis for the etiology of behavioral disorders is that infection by a virus induces neuronal cell dysfunctions resulting in a wide range of behavioral abnormalities. However, a direct linkage between viral infections and neurobehavioral disturbances associated with human psychiatric disorders has not been identified. Here, we show that transgenic mice expressing the phosphoprotein (P) of Borna disease virus (BDV) in glial cells develop behavioral abnormalities, such as enhanced intermale aggressiveness, hyperactivity, and spatial reference memory deficit. We demonstrate that the transgenic brains exhibit a significant reduction in brain-derived neurotrophic factor and serotonin receptor expression, as well as a marked decrease in synaptic density. These results demonstrate that glial expression of BDV P leads to behavioral and neurobiological disturbances resembling those in BDV-infected animals. Furthermore, the lack of reactive astrocytosis and neuronal degeneration in the brains indicates that P can directly induce glial cell dysfunction and also suggests that the transgenic mice may exhibit neuropathological and neurophysiological abnormalities resembling those of psychiatric patients. Our results provide a new insight to explore the relationship between viral infections and neurobehavioral disorders.

Detection of Borna disease virus in a pregnant mare and her fetus

A pregnant mare showing pyrexia, reduced appetite, ataxia and paresis was euthanized and examined for the presence of Borna disease virus (BDV). Her brain, showing multiple neuronal degeneration and necrosis with hemorrhage, and the histologically normal brain of the fetus were both positive for BDV RNA. The BDV nucleotide sequences were identical in the mare and fetus in the second open reading frame (ORF). This is the first report of the possible vertical transmission of BDV in a horse.

Immunohistochemical evaluation of a malignant intestinal carcinoid in a dog

An intestinal carcinoid with multiple metastases was identified in a 5-year-old male Shih Tzu with a clinical history of anemia, fatigue, anorexia, vomiting, intermittent diarrhea, intestinal bleeding, and progressive emaciation. There was a yellowish-white mass 15 mm in diameter in the anterior jejunum and white nodules consistent with metastases in many organs. Histopathologically, the mass consisted of neoplastic cells arranged in lobules, trabeculae, or closely interdigitating islands of cells. Neoplastic cells were generally polygonal with round hyperchromatic nuclei, modest amounts of eosinophilic cytoplasm, and eosinophilic cytoplasmic granules. Mitoses were common. Rosette formations of tumor cells were apparent in metastatic tumors. Immunohistochemically, tumor cells stained positive for cytokeratin 13, synaptophysin, protein gene product 9.5, neuron-specific enolase, chromogranin A, calcitonin gene-related peptide, serotonin (5-HT), and Leu-7. Serum 5-HT concentrations for this dog were increased 10-fold compared with those of normal dogs. All findings were consistent with a diagnosis of a malignant intestinal carcinoid.

Immunohistochemical Detection of Inhibin-α, -βB, and -βA Chains and 3β-hydroxysteroid Dehydrogenase in Canine Testicular Tumors and Normal Testes:

Immunohistochemical detection of inhibin-α, -βA and -βB chains and 3β-hydroxysteroid dehydrogenase (HSD) was carried out on primary testicular tumors from 15 dogs and normal testes from three adult dogs. Histopathologically, the tumors were composed of three types: Leydig cell tumors in five dogs, Sertoli cell tumors in five dogs, and seminoma in five dogs. In normal testes, immunostaining against inhibin-α, -βA, and -βB chains and 3β-HSD revealed positive reactivity in the cytoplasm of Leydig cells. In testicular tumors, immunoreactive cells against inhibin-α, -βA, and -βB chains and 3β-HSD were localized in all Leydig cell tumors but not in any Sertoli cell tumors or seminomas. The results of radioimmunoassay for plasma inhibin in dogs with Leydig cell tumors showed higher concentrations than those in dogs with Sertoli cell tumors and seminomas and those in normal dogs. The concentration of inhibin in the plasma was markedly decreased by the surgical removal of the Leydig cell tumor in one dog. Our findings suggest that inhibin is synthesized by normal and neoplastic Leydig cells in the canine testis, and the secreted inhibin may be inhibin A and inhibin B.

High prevalence of Borna disease virus in domestic cats with neurological disorders in Japan

A total of 15 (T-1-T-15) domestic cats with neurological disorders in Tokyo area were examined for association with Borna disease virus (BDV). None had detectable antibodies to feline immunodeficiency virus (FIV), feline leukemia virus, feline infectious peritonitis virus and Toxoplasma gondii, and only cat T-8 had detectable antibody to FIV. Serological and molecular epidemiological studies revealed a significantly high prevalence of BDV infection in these cats: antibodies against BDV p24 and/or p40 proteins in 10/15 (66.7%) and p24 and/or p40 RNA in peripheral blood mononuclear cells in 8/15 (53.3%). Further, in situ hybridization and immunohistochemistry analyses of the autopsied brain samples derived from one of the cats (T-15) revealed BDV RNA predominantly in neuronal cells in restricted regions, such as olfactory bulb and medulla of cerebrum. Thus, BDV is present in Japanese domestic cats with neurological disorders at a high prevalence.

High susceptibility of Mongolian gerbil (Meriones unguiculatus) to Borna disease virus

Borna disease virus (BDV) is a neurotropic enveloped virus with a nonsegmented, single-, negative-stranded RNA genome. This virus induced encephalitis in experimentally infected adult rats, but in newborn rats BDV established a persistent, tolerant infection with no apparent clinical signs. Here, we report evidence that newborn Mongolian gerbils (Meriones unguiculatus) are more susceptible to experimental intracranial inoculation of horse-derived BDV in persistently infected MDCK cells, compared with similar inoculation in newborn rats. All inoculated newborn gerbils, but not rats, died 30 days after infection. Reverse transcriptase-polymerase chain reaction amplified BDV-specific sequences in several regions including the brain. Histopathological analysis revealed apparent inflammatory reactions in the brains of inoculated gerbils but not rats, although similar levels of BDV RNA were detected in both gerbil and rat brains. BDV-specific antigen and RNA were identified predominantly in neurons in the brains by immunohistochemistry with antibodies to BDV and in situ hybridization with BDV-specific riboprobes, respectively. BDV in the gerbil brain was easily rescued by co-cultivation of the brain homogenate with human oligodendroglioma cells. Thus, gerbils seem to be a useful animal model for studying BDV-induced pathogenesis in the brain.

Systemic atherosclerosis in dogs: histopathological and immunohistochemical studies of atherosclerotic lesions

Histopathological and immunohistochemical studies were carried out on five cases of canine systemic atherosclerosis. The five animals were male, and showed hypercholesterolaemia and hypertriglyceridaemia on biochemical analysis of plasma. Histopathologically, atherosclerotic lesions were seen in the aorta and muscular arteries in many organs, including the heart, spleen, kidneys, lungs, pancreas, alimentary tract, urogenital organs, eyes, prostate and urinary bladder. The lesions were characterized by the deposition of lipids and infiltration of lipid-laden foamy cells in the tunica intima and tunica media, sometimes forming fibrofatty plaques, containing abundant sudanophilic material, cholesterol clefts and mineralized material. The lesions started in the tunica intima and extended to the tunica media and tunica adventitia. Immunohistochemical examination with canine apolipoprotein B-100 (CApoB-100) antibody identified the lipids containing low density lipoprotein. Immunoreactivity to CApoB-100 antibody was recognized in the tunica intima, lipid-laden foamy cell cytoplasm and smooth muscle cells in the tunica media, and fibrofatty plaque. These histopathological and immunohistochemical features were similar to those of human atherosclerotic lesions.

Chlamydial infection in canine atherosclerotic lesions.

We attempted to detect chlamydial antigens in canine atherosclerotic lesions from seven dogs by immunohistochemical technique using anti-Chlamydia psittaci (C. psittaci) polyclonal and anti-C. pneumoniae monoclonal antibodies. Immunopositive signals to both antibodies were recognized in the atherosclerotic lesions of the aortas, coronary and splenic arteries of all dogs. Positive signals were found in the foamy cytoplasm of infiltrated macrophages and extracellular matrices in the lesions. In some lesions, cytoplasm of the endothelial cells and smooth muscle cells was also immunopositive against both antibodies. By electron microscopy, chlamydial microorganisms were found in the cytoplasm of endothelial cells and smooth muscle cells. Using polymerase chain reaction (PCR), detection of C. pneumoniae DNAs were performed in the spleen, heart (coronary arteries) and kidney in one of the seven dogs. Positive 314 bp PCR products were obtained in all samples of the dog. These results confirmed the presence of viable Chlamydiae in atheromas and supported the conclusion that the organism may be an active factor in the pathogenesis of canine, as well as human atherosclerosis.

Localized Amyloidosis in Canine Mammary Tumors

Histopathologic and immunohistochemical examinations were performed on localized amyloidosis associated with mammary tumors in two dogs. These tumors were identified as adenoma and adenocarcinoma. An acellular, amorphous pale eosinophilic material (amyloid) was observed in the lumina of acini lined by neoplastic cells and in the stroma of the tumors. Concentrically laminated pale eosinophilic bodies (corpora amylacea) were also found in the lumina of the acini. Amyloid and corpora amylacea stained positively with Congo red with and without 5% potassium permanganate pretreatment and revealed a green birefringence under polarized light. Corpora amylacea showed an occasional Maltese-cross pattern. Immunohistochemically, amyloid and corpora amylacea usually stained positively with anti-bovine α-casein antibody but negatively with anti-human amyloid AA, anti-bovine κ-light and λ-light chains, anti-human lactoferrin, anti-human transferrin, anti-human secretory component, and anti-human polyglucosan antibodies. These findings suggested that the amyloid deposition in these canine mammary tumors was related to lactating casein.