Yasuho Taura

A comparative study of gut-associated lymphoid tissue in calf and chicken

The calf contains two types of Peyers patches (PPs): jejunal and ileal. The ileal PP has been thought to be equivalent to the bursa of Fabricius (BF) as a central lymphoid organ. The morphologies of ileal and jejunal PPs in the calf were compared with those of the BF and the caecal tonsil (CT) in the chicken. Immunoglobulin G–positive (IgG+) cells appear in the follicles of them all and exhibited a dendritic appearance after birth. We investigated whether the IgG in these follicles was produced in situ. IgG‐producing cells were detected in the follicular medullas of the jejunal PP and the CT, but not in those of the ileal PP and the BF. CD4+ cells were distributed in the follicular medullas of the jejunal PP and the CT, but not in those of the ileal PP and the BF. The data suggest that Ig class switching occurs in both jejunal PP follicles and CT follicles, but does not occur in either the ileal PP follicles or the bursal follicles. Because CD4+ T cells would be prerequisite for Ig class switching in these follicles, IgG+ cells of the follicular medullas in the ileal PP and the BF would trap immune complexes from the gut lumen. The primary B‐cell repertoire might be selected by gut‐derived antigens in the ileal PP and the BF before seeding the periphery. Anat Rec 266:207–217, 2002.

A comparative study of germinal center: fowls and mammals

The mammalian germinal center is organized into a dark zone containing proliferating centroblasts and a light zone filled with nondividing B cells (called centrocytes), follicular dendritic cells and a few scattered T cells. We clarified these two zones in the chicken germinal center with immunohistology. Proliferating cells and immunoglobulin negative cells were detected in the circumference ring of the chicken germinal center. The central part of the chicken germinal center contained B cells expressing immunoglobulin, follicular dendritic cells and a few T cells. Most of the B cells in the central part of the chicken germinal center did not enter into the S phase. These results suggest that the chicken germinal center is also organized into the dark zone (the circumference ring of germinal center) and the light zone (the central part of germinal center).

Immunobiology of chicken germinal center: I. Changes in surface Ig class expression in the chicken splenic germinal center after antigenic stimulation

The germinal center (GC) develops after antigenic stimulation and is thought to occur at the site of various immune responses. We separated a single GC from chicken spleen after antigenic stimulation. Flow cytometric analysis of the cells derived from a single GC and RT-PCR analysis of Ig mRNA expression in GC was performed. Direct evidence indicates that: (1) there was a considerable difference in the cell population of each GC, (2) the ratio of CD3(+) cells in a GC remains constant at 10-20%, (3) the highest proportion of sIgY(+) cells in a GC occurs 1 week after the time of highest proportion of sIgM(+) cells, and (4) RT-PCR analysis was used to detect IgY mRNA expression in a GC. The continuous existence of CD3(+) cells, the alterations in sIgM(+) and sIgY(+) cell ratios, and the expression of IgY mRNA strongly suggest that Ig class switching occurs in the GC during an immune response.

Development of maternal IgG-free chick obtained from surgically bursectomized hen

IgG-free eggs and chicks were developed, so as to study the role of maternal IgG in the development of the immune system. Surgical bursectomy on the 18th day of incubation deprived chickens of B cells and eliminated IgG synthesis. Bursectomized chickens are usually dead before sexual maturity under conventional conditions. When surgically bursectomized chickens were housed in an isolated clean room and antibiotics were administered to them, they could survive to sexual maturity. Finally, we succeeded in obtaining IgG-free fertilized eggs and maternal IgG-free chicks from surgically bursectomized hens. The amount of yolk IgG in IgG-free eggs was one-ten thousandth less than that in normal eggs. The level of IgM in the serum of maternal IgG-free chicks reached six times higher than that of normal chicks 5 days after hatching.

Clinical observations of Babesia gibsoni infection with low parasitaemia confirmed by PCR in dogs.

2004). In preliminary experiments, this PCR was able to detect approximately 10 B gibsoni-infected red blood cells in 1 μl of peripheral blood. All 35 animals with B gibsoni infection were positive by the PCR. To confirm the PCR findings, nucleotide sequences of randomly selected products of the B gibsoni-specific PCR were determined by direct sequence analysis, using the method described by Inokuma and others (2003). All the analysed sequences showed 100 per cent homology with B gibsoni Asia-1 (GenBank accession number AF175300). The animals with IMHA showed an acute onset of signs similar to those of B gibsoni infection, such as haemolytic and regenerative anaemia, icterus, anorexia or haematuria, at presentation. All eight animals with IMHA were found to be negative for B gibsoni infection by PCR. The information obtained for the 35 babesiosis cases and eight IHMA cases included histories and the findings of physical examination, complete blood counts, serum biochemical analysis and abdominal radiography. To compare the data from the dogs with low parasitaemia with the data from those with moderate to severe parasitaemia or with IMHA cases, chisquared tests and one-way analysis of variance were performed by using StatView v 5.0 (Hulinks). When the clinical and laboratory findings of the Babesia-infected animals showing low parasitaemia were compared with those of the dogs with moderate to severe parasitaemia, there were no significant differences between the two groups (Table 1). Although the numbers of dogs that showed icterus and the mean total bilirubin level in dogs with more severe parasitaemia were slightly higher than those of the dogs with low parasitaemia, the differences were not significant. Oxidative damage to erythrocytes induced by B gibsoni infection is thought to result in severe anaemia even in the presence of low parasitaemia (Otsuka and others 2002). Overall, the degree of parasitaemia in the B gibsoni-infected dogs did not relate to the clinical and laboratory findings. The clinical and laboratory findings in the dogs with B gibsoni infection with low parasitaemia were also compared with Clinical observations of Babesia gibsoni infection with low parasitaemia confirmed by PCR in dogs

Primary chondrosarcoma in the skull of a dog.

Chondrosarcoma of the skull is a rare primary malignant tumor that is slow-growing, but locally aggressive. A 5-year-old, golden retriever was presented to our hospital with a swelling in the left side of her head, and the swelling had slowly enlarged over the previous month. There were no significant changes on the neurological examination. A computed tomography scan revealed a large mass involving bone destruction and prominent matrix mineralization. T1-weighted magnetic resonance imaging showed a slightly low-signal intensity area and a T2-weighted image revealed marked, high-signal intensity. There was compression of the adjacent brain parenchyma. Histopathological examination confirmed the lesion to be a chondrosarcoma.

Malignant mixed tumor in the salivary gland of a cat.

The presence of a malignant mixed tumor, also known as a carcinosarcoma, in the salivary gland is very rare. Such tumors, which are typically aggressive, are characterized by the presence of carcinomatous and sarcomatous components. A 9-year-old neutered female domestic short-haired cat presented with swelling in the right mandibular lesion that had rapidly enlarged over the previous 3 weeks. Physical examination revealed a large, fluctuated and painless subcutaneous swelling that was associated with a firm mass. Radiographs of the head revealed a soft-tissue density that involved faint circular calcific opacity. Contrast-enhanced computed tomography revealed that the peripheral capsulated cystic area had a contrast enhanced region without bone lysis. The cat received a total excision of the mass and postoperative radiotherapy. Histopathological analysis of the mass revealed that it was a malignant mixed tumor. Metastasis to the lung was discovered 7 weeks later, at which time treatment was stopped.

Application of ventriculoperitoneal shunt as a treatment for hydrocephalus in a dog with syringomyelia and Chiari I malformation

A twenty-month-old Chihuahua male dog was presented to us suffering with ataxia. Based on the physical examination, X-ray and magnetic resonance imaging (MRI) examinations, we diagnosed the dog with hydrocephalus, Chiari I malformation and syringomyelia. Treatment consisted of internal medical treatment and the placement of a ventriculoperitoneal (VP) shunt. The ventricular dilatation was relieved and the dog improved neurologically; however, the Chiari I malformation and syringomyelia remained after surgically positioning the VP shunt.

Surgical Management of Combined Hydrocephalus, Syringohydromyelia, and Ventricular Cyst in a Dog

Combined hydrocephalus, syringohydromyelia, and a ventricular cyst were found by magnetic resonance imaging in a 7-month-old, male miniature dachshund with gait abnormalities and altered mentation. Clinical signs did not improve with prednisone therapy. Ventriculoperitoneal shunting improved the clinical signs and anatomical abnormalities. Repeated operations were needed to replace the ventricular drainage tube at 3 and 31 months after the first surgery. The animal died suddenly with severe tonic-clonic, generalized seizures 3 weeks after the third operation. Ventriculoperitoneal shunting may be a viable treatment for syringohydromyelia associated with hydrocephalus.

A new hepatic encephalopathy model to monitor the change of neural amino acids and astrocytes with behaviour disorder.

Background/Aims: To elucidate the pathogenesis of hepatic encephalopathy (HE), we developed a new HE model with behaviour disorder.