Suppressive effect of deoxynivalenol, a Fusarium mycotoxin, on bovine and porcine neutrophil chemiluminescence: an in vitro study

We evaluated the immunotoxicity of deoxynivalenol (DON), a Fusarium mycotoxin, on bovine and porcine neutrophils in vitro by using two function parameters, luminol-dependent chemiluminescence and random migration under agarose. A 2-hr DON treatment suppressed the chemiluminescence of bovine and porcine cells by 42% and 35% (on average) at 10(-5)M, and by 19% and 26% at 10(-6)M. Slight suppression was observed at concentrations lower than 10(-6)M. However, after an 18-hr DON treatment, random migration of neutrophils of both species remained unaffected, even at the highest concentration (10(-5)M). Although further extensive studies are needed, to our knowledge this is the first study to have revealed in vitro that DON can affect neutrophil function.     

A spontaneously occurring malignant ovarian Sertoli cell tumor in a young Sprague Dawley rat

Primary ovarian tumors are generally uncommon in rats used in toxicologic studies. A malignant Sertoli cell tumor was present in the ovary of a 19-week-old female Sprague Dawley rat. Macroscopically, the mass was white and firm, 10 × 13 × 17 mm in size, and located in the right ovary. Histopathologically, the mass was composed of nests of pleomorphic cells, which formed seminiferous-like tubules separated by a thin fibrovascular stroma. The tubules were lined by tumor cells, which had basally located nuclei and abundant eosinophilic and vacuolated cytoplasm. In some areas, the tumor cells were arranged in a retiform growth pattern, mimicking a rete testis/ovarii. Disseminated metastases to the surfaces of the mesentery, spleen and liver were also present. Immunohistochemically, many tumor cells were strongly positive for vimentin, estrogen receptor α and Ki 67. Some tumor cells were positive for pancytokeratin and inhibin α. These findings closely resemble those of an ovarian-derived human malignant Sertoli cell tumor. From our review of the literature, we believe this is the first report of a spontaneous malignant Sertoli cell tumor in the ovary of a young laboratory rat. This case might provide useful historical control information for rat toxicity studies.     

Malignant Peritoneal Mesothelioma with a Sarcomatoid Growth Pattern and Signet-Ring-Like Structure in a Female F344 Rat

We report a biphasic malignant mesothelioma in an aged female F344/DuCrlCrlj rat. Macroscopically, multiple pale brown nodules were observed in the abdominal cavity with retention of bloody ascites. Histopathologically, the tumor cells spread over the peritoneum and formed masses on the surface and underlying adipose tissues. The tumor cells dominantly proliferated in a solid, nodular or nest-like pattern with modest amount of fibrillar connective tissues, which contained hyaluronan. The tumor consisted of ovoid, polygonal or spindle-shaped cells that possessed eosinophilic cytoplasms including glycogen; some tumor cells showed a signet-ring-like structure. Multinucleated cells and mitosis were found frequently, and direct invasion to intra-abdominal organs and intravascular metastasis to the liver were observed. Immunohistochemically, keratin and mesothelin were strongly positive in most of tumor cells, while vimentin was mainly positive in spindle-shaped cells. Podoplanin was also positive, particularly in the cell membrane of tumor cells. Electron microscopically, tumor cells showed an intercellular desmosome-like structure, basement membrane and microvillus. We diagnosed the case as a malignant peritoneal mesothelioma with a sarcomatoid growth pattern and signet-ring-like structure.     

PCR detection of Porcine circovirus type 2 DNA in whole blood,serum, oropharyngeal swab,nasal swab,and feces from experimentally infected pigs and field cases

Porcine circovirus type 2 (PCV2) shedding patterns were investigated by polymerase chain reaction (PCR) for the detection of PCV2 DNA, and the diagnostic suitability of a sample for the PCR was examined by using different types of samples. In the experimental infection, sixteen pigs were inoculated intranasally with PCV2. The samples, including oropharyngeal and nasal swabs, feces, whole blood and serum became positive for PCV2 DNA by PCR immediately after the inoculation, and almost all samples remained positive during the observation period, post-inoculation-day 70. Field samples were collected from 313 pigs in five different age groups. The overall percentages of positive samples in the whole blood, nasal swabs, and feces detected by PCR were 30.4%, 19.2%, and 20.4%, respectively. The frequency of positive samples increased after the nursery stages and reached a peak in the 3 to 4-month-old pigs. These results indicate that PCV2 infection may occur after weaning, that PCV2 DNA may be present in whole blood for a long period after infection, and that whole blood and serum are the most suitable sample types for the PCR analysis of PCV2.     

Localization of eNOS in the olfactory epithelium of the rat

Nitric oxide (NO) is a free radical and produced from L-arginine by nitric oxide synthase (NOS). Since NO is recently suggested to be involved in olfactory perception, the expression of eNOS, an isoform of NOS, was examined in the rat olfactory epithelium. The activity of NADPH-diaphorase was also examined as a marker of NOS. In the dorsomedial region of the nasal cavity, intensely positive reactions for NADPH-diaphorase were observed in the entire cytoplasm of sensory cells (olfactory cells). By immunohistochemistry, intensely positive reactions for eNOS were also found in the dorsomedial region of the nasal cavity. These reactions were observed on the free border of the olfactory epithelium. By immunoelectron microscopy, positive reactions for eNOS were found in the cilia of olfactory cells. In addition, in situ hybridization analysis of the olfactory epithelium revealed the expression of eNOS mRNA in the olfactory cells. These results indicate the presence of eNOS in the olfactory cells of the rat, and differential expression of eNOS in the olfactory epithelium depending on the regions of the nasal cavity. In addition, NO produced by eNOS may be involved in olfactory perception in the cilia of olfactory cells.     

N -Methyl- N -nitrosourea-induced Renal Tumors in Rats: Immunohistochemical Comparison to Human Wilms Tumors

N-Methyl-N-nitrosourea (MNU)-induced renal tumors in rats and Wilms tumors in humans were compared. Renal mesenchymal tumors (RMTs) and nephroblastomas (blastemal and epithelial components) in female Lewis rats treated with a single intraperitoneal injection of 50 mg/kg MNU at birth and Wilms tumors (blastemal, epithelial and mesenchymal components) in humans were analyzed for the expression of pancytokeratin (CK), vimentin, p63, α-smooth muscle actin (SMA), desmin, S-100, CD57, CD117/c-kit, Wilms tumor 1 protein (WT1) and β-catenin. The mesenchymal components of rat RMTs and human Wilms tumors expressed vimentin, SMA and β-catenin. The blastemal components of rat nephroblastomas and human Wilms tumors expressed vimentin, CD117/c-kit and β-catenin. The epithelial components of rat nephroblastomas and human Wilms tumors expressed vimentin and β-catenin. WT1 was expressed in different cellular components of rat tumors as compared with human Wilms tumors; the expression was seen in mesenchymal tumors and blastemal components of nephroblastomas in rats and epithelial components in human Wilms tumors. CK, p63 and CD57 were not expressed in rat RMTs or nephroblastomas, while CK and WT1 were expressed in epithelial components and CD57 was expressed in blastemal and epithelial components of human Wilms tumors. Rat and human tumors were universally negative for the expression of desmin and S-100. The immunohistochemical characteristics of rat renal tumors and human Wilms tumors may provide valuable information on the differences in renal oncogenesis and biology between the two species.     

Changes in the anatomy of surface and liquid uptake of wood after laser incising

The effects of laser incising on the surface of heat-affected zones (HAZs) and liquid uptake of wood were examined. Deep pin holes were incised on the tangential section of the wood with a laser beam of 1 kW in power with varied pulse widths, and the HAZs of the holes were investigated using scanning electron microscopy. The length of liquid uptake passing through HAZs surfaces was then measured. It was observed that the HAZs were unable to maintain normal porous structure, and smooth surfaces such as that of wood charcoal were also not observed. This is because the composite of the middle lamella completely melted, which led to a decrease in the length of liquid uptake. In addition, the release of high gas-pressure and thermal energy during the laser-incising process did not damage the tylose and the aspirated pit in the longitudinal direction. Because of this, the liquid movement remained blocked. However, the incising holes provided additional liquid-intake points, resulting in greater intake capacity. Moreover, it was observed that improvement of liquid impregnation is related to hole diameter.     

Ophiostomatoid fungi associated with bark beetles onAbies veitchii in wave-regenerated forests

Relationships between tree mortality and bark beetle infestation onAbies veitchii at the wave-regenerated forest in Mt. Asahi, Okuchichibu area were investigated. Most of the firs with green needles and newly developed current year’s shoots in the dieback zone were heavily infested by bark beetles before the death of the trees. After heavy infestation of beetles, about half of the infested firs died within the year, and the other half died in the next year. When the species composition of bark beetles and associated ophiostomatoid fungi were investigated in Mt. Asahi and also at a typical wave-regenerated forest in Mt. Shimagare, Yatsugatake area,Cryphalus montanus andC. piceae were dominant beetle species for Mt. Asahi and Mt. Shimagare, respectively.Ophiostoma subalpinum andO. europhioides were dominant fungal species at both wave-generated forests. BecauseO. subalpinum was detected more frequently from deeper areas of sapwood thanO. europhioides, it was suggested that the fungal species may accelerate the death of stressed firs in wave-regenerated forests. Contribution No. 169, Laboratory of Plant Parasitic Mycology, Institute of Agriculture and Forestry, University of Tsukuba.