Our previous studies showed that the passage of the Friend virus complex through rats generated variant MuLVs, designated PVC111, PVC211, PVC321 and PVC441, that induced neurological disorders associated with tremor and paralysis. In this study, we tested the pathogenicity of four different PVC viruses in mice. Although histopathological studies revealed spongiform degeneration in the spinal cords of NFS mice infected with each PVC virus, only PVC441 frequently induced tremor and paralysis. After a long latency, all of these viruses induced leukemia associated with severe anemia. Further studied with PVC441 revealed dose- and age-dependence for tremor induction. In contrast to NFS mice, BALB/c, DBA/2 and C57BL/6 mice infected with PVC441 virus showed no neurological symptoms, although the virus could be isolated from the tissues of central nervous system. Despite the absence of neurological symptoms, a high degree of neuronal degeneration in the lumbar spinal cord was found in PVC441-infected BALB/c mice. A low degree of neuronal degeneration was found in PVC441-infected DBA/2 or C57BL/6 mice. Genetic crosses of these resistant mice with susceptible NFS mice indicated that resistance to tremor induction by PVC441 was dominant in all mouse strains and suggested that various host genes may control the susceptibility of mice to tremor induction by PVC441 virus.

View full abstract

The present study was designed to confirm the usefulness of contrast-enhanced magnetic resonance imaging (MRI) in diagnosing strokes of stroke-prone spontaneously hypertensive rats (SHRSP) and middle cerebral artery (MCA) occlusion, hepatocellular carcinoma and hydronephrosis of each experimental rat model. Male Sprague-Dawley rats (250-500 g), male SHRSP (ca. 250 g) and male F344 rats (ca. 300 g) were used for the investigation. Gadodiamide injection (Omniscan, Daiichi Pharmaceutical Co., Ltd. and Nycomed AS, Norway) was administered intravenously as the contrast agent at a dose of 0.1 mmol/kg except in hydronephrosis, where a dose of 0.05 mmol/kg was used. Magnetic resonance (MR) images were obtained with a 1.5 T or a 2.0 T magnetic field strength MRI unit. The signal intensity of the stroke lesions was increased after administration of gadodiamide injection in SHRSP and MCA-occluded rats. Hepatocellular carcinoma was undetectable without the use of the contrast agent, but the signal intensity of the tumor increased after administration of the gadodiamide injection, allowing the lesions to be detected. The signal intensity of the renal medulla increased in the non-ligated kidney, but not in the hydronephrotic kidney. The information given by the post-contrast images were superior to those obtained from thd pre-contrast images in all the models. Contrast effects in SHRSP and MCA-occluded rats were related to differences in capillary permeability, those in rats with hepatocellular carcinoma depended on differences in vascularity, and those in hydronephrotic rats depended on blood flow and permeability.

View full abstract

Nine-week-old pigs were inoculated intranasally with 6.10×10³ (group 10³), 10⁵ (group 10⁵) and 10⁷ (group 10⁷) colony-forming unit of Actinobacillus pleuropneumoniae (App) serotype 1 designated HA-337 strain, respectively. One pig in group 10⁵ and 2 pigs in group 10⁷ died with dispnea and hemorrhagic pleuropneumonia within 20 to 48 hr post inoculation (PI). All pigs necropsied on 7 days in groups 10⁵ and 10⁷ had focal fibrous pleuropneumonia. Histologically, pulmonary lesions were classified into three stages; peracute, acute and subacute. Fatal cases in group 10⁷ had peracute lesion composed of severe edema, hemorrhage and necrobiosis of alveoli, with mononuclear cells infiltration in the dilated interlobulus. The fatal case in group 10⁵ had acute pulmonary lesion composed of focal or linear infiltration of round and fusiform cells that frequently showed swirling pattern in alveoli. The surviving cases in group 10⁵ and 10⁷ had subacute lesion composed of multifocal pulmonary necrosis surrounded by fibrous tissue. The swirling pattern was clearly seen in demarcation zone. Immunohistochemically, App antigens scattered as intact bacteria in alveoli, dilated interlobular septa and pleura, and lymph vessels in peracute and acute lesions. Areas of necrosis were also stained weakly. Although no antigen was detected in cytoplasm of macrophages and infiltrated cells in peracute lesions, App antigen was detected as positively stained mass in cytoplasm of some macrophages in acute lesions. In subacute lesions, App antigens were recognized as intact bacteria in necrotic areas and among the swirling pattern cells of demarcation zone. Macrophages had App antigens as a large mass of pigment in the cytoplasm in area of fibrosis.

View full abstract

Two kinds of bovine c-Myb, the 75 kDa full-length (FL) c-Myb from the thymic type of sporadic bovine lymphosarcoma (SBL) cells, and 65 kDa deleted (DEL) c-Myb, which is an internally deleted form (85 amino acids corresponding to the negative regulatory domain) from calf-type SBL were found. To investigate the relationship between internal deletion and transforming capacity, we constructed retroviral vectors carrying cDNA that encoded either FL- or DEL-Myb protein, and transfected them to mouse fetal liver cells. In spite of the high trans-activating capacity of DELMyb, DELMyb and FLMyb showed no significant difference in oncogenic capability by measurement of colony formation in soft agar or in methylcellulose medium. Thus, the internal deletion of the c-myb gene is competent for transactivation but not directly relevant to transformation of mouse hemopoietic cells.

View full abstract

The effects of the excessive administration of the vitamin AD₃E (V-AD₃E) premix, vitamin A (V-A) or vitamin D₃ (V-D₃) on experimental development of Hyena disease in the calves were examined. Hyena disease was recognized in 4 calves, both of the 2 calves administered a high dose of V-AD₃E premix (V-A 3, 000, 000, V-D₃ 300, 000, and V-E 1, 200 I.U./day, V-AD₃E group), 1 of the 2 calves administered a half dose of the V-AD₃E premix, and 1 of the 2 calves administered only V-A (V-A 3, 000, 000 I.U./day, V-A group) when each vitamin was administered orally for 10 days from 1 week after birth. Both of 2 calves administered only V-D₃ (V-D₃ 300, 000 I.U./day) did not developed. In the 4 calves with Hyena disease (Hyena calves), the plasma retinylpalmitate showed high values which was suggesting the hypervitaminosis A, and the epiphysial growth plate was narrow and destroyed structure of column. Compared with the Hyena calf in the V-A group, the Hyena calves in the V-AD₃E group showed earlier appearance time of Hyena disease, lower growth rate and shorter lengths of fore and hind limb bones. In conclusion, the present findings suggested that excessive V-A administration to suckling calves might cause Hyena disease by V-A effects to the epiphysial growth plate, moreover such effects may be promoted by the V-D₃.

View full abstract

In this study fibrinolytic assay systems were used to assess the plasminogen activator (PA) potential and plasmin generating ability of oocyte-cumulus complexes isolated from preovulatory bovine follicles (2-8 mm diameter) and of fertilized oocytes from the day of fertilization up to, and including, the hatched blastocyst stage (day 12). During embryo development, the culture medium was changed every 24 hr and samples examined for PA activity. Irrespective of the stage of maturity, no plasminogen or PA could be detected in unfertilized oocytes from which the cumulus layer had been removed. Both plasminogen and PA were found in the cumulus layer indicating that this, rather than the oocyte, was the source of these proteins in the oocyte-cumulus complex. Following oocyte fertilization, no PA activity was detected in either the developing embryo or in the culture medium before day 7. When the embryos had developed to the expanded blastocyst stage, days 7-8, PA production began with activity being detected in both the embryos and their culture medium. Between days 8 and 12, when embryos had reached the hatched blastocyst stage, the PA activity had increased significantly (p<0.05). Analysis of the culture media confirmed this increase in production of PA activity and, based on zymography, it was estimated that the molecular weight of the PA was 78 k daltons.

View full abstract

The effect of serum thymic factor (FTS) was evaluated from the immunoresponse augmented in canine monocytes and polymorphonuclear cells (PMN) using the chemiluminescence technique. FTS did not affect the number of leukocytes and differential count of leukocytes. CL activity of the whole blood was significantly elevated by FTS from 72 hr to 120 hr after administration (p<0.05), and that at 96 hr after administration was about 3-fold higher than that before the administration. The CL response of PMN was significantly elevated by FTS administration from 24 hr to 96 hr after administration (p<0.05), and that at 48 hr after administration was about 7-fold higher than prior treatment. FTS also significantly elevated the CL response of monocyte from 24 hr to 96 hr after administration (p<0.01), and the CL count of monocyte in 24 hr and 48 hr was about 100-fold higher than that before FTS administration. These findings suggested that FTS may be efficacious and useful immuno-potentiator for canine monocytes and PMN.

View full abstract

Spermatogenic cycle in the testis of the Japanese black bear (Selenarctos thibetanus japonicus) was studied by light and transmission electron microscopy. By light microscopy, spermatids were allocated into eleven steps based on morphological changes in the nucleus and the acrosome of spermatids. Cellular associations of the seminiferous epithelium were allocated into eight stages based on the changes in the nucleus and acrosome of spermatids, appearance of meiotic figures and time of spermiation. Cross-sections of the seminiferous tubule seldom contained more than one type of stage. Spermatids at steps 1-2 had the well-developed Golgi complex. The crescent-shaped Golgi complex was accompanied by the acrosome extending over the nucleus at steps 3-5. At step 6, spermatids faced the base, and the outer membrane of the acrosome converged upon the plasma membrane of spermatids. The acrosome projected into the cytoplasm of Sertoli cells at step 9. At step 11, most of the cytoplasm was phagocytosed by Sertoli cells, and spermatids were released in the lumen to become spermatozoa.

View full abstract

The pattern of neuropeptide Y (NPY)- and vasoactive intestinal polypeptide (VIP)-immunoreactive (IR) innervation was investigated in the cerebral arterial tree and choroid plexus of the newt by the use of an indirect immunofluorescence technique combined with chemical sympathectomy (6-OHDA). The data presented here, in conjunction with histochemical data reported previously, showed the following characteristic features of cerebrovascular innervation in this urodelan species. (1) The cerebral arterial tree and choroid plexus had unbalanced NPY-IR and VIP-IR innervation, characterized by the absence or a markedly lesser density of VIP-IR nerves. (2) All or nearly all of the NPY-IR nerves were sympathetic in nature. (3) A few cerebral perivascular NPY-IR nerves in some individuals originated from the sympathetic NPY-IR nerve cells intrinsic to the major cerebral arteries of the anterior circulatory system. (4) Acetylcholinesterase-positive neurons lacking both NPY and VIP immunoreactivities are a major nerve type in cerebrovascular parasympathetic innervation. The preferential NPY-IR innervation of the plexus microvascular-epithelial regions must be considered in relation to its special functions, such as the regulation of microcirculation, and cerebrospinal fluid (CSF) production and transportation. CSF is vital for the movement of nutrients and metabolites in the newt brain.

View full abstract

To elucidate the role of T cell subpopulations in the protective cell-mediated immune response at the initial phase of infection with Babesia microti (BM) and B.rodhaini (BR), the changes in the course of infection and anti-parasite delayed type hypersensitivity (DTH) response after BM or BR inoculation were investigated in Lyt-2⁺ T cell- or L3T4⁺ T cell-depleted mice. Depletion of Lyt-2⁺ T cells strongly enhanced the resistance to BM infection, whereas it increased the susceptibility to BR infection. In contrast, depletion of L3T4⁺ T cells increased susceptibility to BM infection, while it enhanced resistance to BR infection. The anti-parasite DTH response in BM-infected mice was significantly enhanced by depletion of Lyt-2⁺ T cells, while significantly reduced by depletion of L3T4⁺ T cells. No effects of depletion of either Lyt-2⁺ or L3T4⁺ T cells on DTH response was observed in BR-infected mice. From these results, it was suggested that the roles of Lyt-2⁺ and L3T4⁺ T cells in the protective cell-mediated immune response at the initial phase of infection were different between BM- and BR-infected mice, resulting in the difference in their course of infection.

View full abstract

The effects of ventilation at positive end-expiratory pressure (PEEP) on extravascular lung water (EVLW) and cardiopulmonary function were studied in dogs with experimental severe hydrostatic pulmonary edema, which was generated by inflating a left atrial balloon and simultaneously injecting warm 5% glucose solution into the pulmonary artery. The EVLW was measured by the double indicator dilution method using heat and sodium ions. All the dogs were ventilated at zero end-expiratory pressure (ZEEP) until the EVLW had increased by 200-300% (maximal edema), when they were divided into two groups, one of which (n=6) was ventilated at a PEEP of 10cmH₂O throughout the 4 hr study period (PEEP group) and the other (n=6) was maintained at ZEEP during their survival period (ZEEP group). All the dogs in the PEEP group survived ventilation for 4 hr, whereas all those in the ZEEP group died within 3 hr, (2 within 1 hr, 1 between 1 and 2 hr and 3 between 2 and 3 hr). The EVLW of the PEEP group remained unchanged throughout the 4 hr study period, whereas that of the ZEEP group showed a tendency to increase. The arterial oxygen tension (PaO₂) increased significantly throughout the 4 hr period of ventilation in the PEEP group but tended to decrease in the ZEEP group. In conclusion, PEEP improves gaseous exchange, but does not decrease the EVLW in dogs with experimental severe hydrostatic edema.

View full abstract

We developed an enzyme-linked immunosorbent assay (ELISA) to detect antibodies against PRRS virus in swine sera. The ELISA antigen was prepared from MARC-145 cells infected with PRRS virus. The results from serial serum samples from experimentally infected and random swine indicated that the ELISA was more sensitive than indirect fluorescent and immunoperoxidase monolayer assays. Since the ELISA enables many sera to be simultaneously and rapidly tested, it was useful for detection antibodies against PRRS virus in swine sera.

View full abstract

We developed a sensitive and specific method, reverse transcriptase-polymerase chain reaction (RT-PCR) method, for detection of turkey rhinotracheitis virus (TRTV). Two sets of primers were designed from F protein gene sequence of TRTV 3B strain. Sensitivity of detection by nested PCR with the primers corresponded to 0.4 TCID₅₀. Applying this method to a field case of swollen head syndrome (SHS), TRTV could be detected directly from chicken trachea and turbinates. It was identified that this method was very useful to examine the relation of TRTV and SHS.

View full abstract

The chemiluminescence response of cervine neutrophils to various stimuli was investigated in comparison with that of bovine and human homologues. The cervine cells showed a strong and consistent response, as observed in other species, to opsonized zymosan, phorbol myristate acetate and concanavalin A. The cells, however, like bovine homologues, failed to respond to n-formyl-methionyl-leucyl-phenylalanine which is a potent stimulant of human neutrophils.

View full abstract

Two types of chicken egg yolk antibody samples for oral passage trials in calves were prepared; (1) hydroxypropyl methylcellulose phthalate (HPMCP) antibody powder (HAP) - a powder produced by spray-drying a supernatant obtained after precipitation of lipids from egg yolk with HPMCP and (2) control antibody powder (CAP) - a powder produced from an antibody solution without HPMCP. Antibody activity and pattern of distribution of both antibody preparations in the gastrointestinal tract of calves were compared by enzyme-linked immunosorbent assay. At 2 hr post administration, anti-K99 fimbrial antibodies from both the CAP and the HAP were detected in the abomasum of calves with titers of 1:128 and 1:256, respectively. However, at 4 hr, anti-K99 fimbrial titers of the CAP and the HAP were reduced to 1:2 and 1:64, respectively, due to digestion in the abomasum. These results indicated that the egg yolk antibody powder with HPMCP was more resistant against gastric juice in the stomach, thereby, ensuring a transfer of functional antibodies to the small intestine of calves after oral administration.

View full abstract

An ELISA test for the detection of antibody against S.suis type 2 in pigs was developed and applied to field sera. The best sensitivity and specificity of ELISA were obtained when a purified polysaccharide antigen was used. It showed no cross reaction with sera against other serotypes of S.suis and other pathogenic bacteria. A total of 264 sera were collected from 20 pig farms and examined with the antibody against S.suis type 2. In the affected farms, 17.0% of pigs tested were positive, 9.8% in the adjacent farms, but only 3.4% in the free farms. The difference of the positive percentages between the affected and the free farms was statistically significant (P<0.05).

View full abstract

Apart from apoptosis, a type of parenchymal cell death by the cell protruding into the capillary lumen was observed in the adrenal gland of normal Sprague-Dawley rats. Ultrathin sections were prepared in the conventional manner and were examined by electron microscopy. The protruded cells (p-cells) had the electron lucent cytoplasm and the p-cells with ruptured cell membranes were observed in the cabillaries. The egress of p-cells was either through the endothelial gaps, or following the rupture of capillary endothelia. The cytoplasmic matrices of the dying p-cells were seen to scatter in the cabillary lumen where the nuclei, mitochondria and granules remained morphologically intact. The p-cells were seen in the capillaries of medulla, but restricted to those of zona reticularis in the cortex.

View full abstract

Nucleotide sequence, 1713nt in length, of porcine reproductive and respiratory syndrome virus (PRRSV) isolated in Japan was determined. The sequence encompassed 3 overlapping open reading frames (ORFs), ORF5 to ORF7. These ORFs encodes major structural proteins of PRRSV. The deduced amino acid sequence of each ORF showed higher than 87.5% identity with an American isolate, and lower (54.6 to 80.5%) identity with an European isolate. This result supported a previous report about antigenic characteristics of the EDRD-1 strain. Leader-body junction sequence in subgenomic mRNA of the EDRD-1 strain was determined by sequencing cDNA clones of subgenomic RNAs. A common sequence motif of 5 nucleotide, represented by UA(A/G)CC, was identified as the junction sequence.

View full abstract

Congestive heart failure resulted from bilateral atrioventricular insufficiency was diagnosed in two, small breed, intact male aged dogs. In both cases, the clinical signs were mainly associated with right heart failure, while those related to left heart failure were seldom observed. Radiographic and echocardiographic examinations revealed the dilatation of the right heart due to tricuspid valve insufficiency. Mitral regurgitation was also observed without pulmonary hypertension. Both patients responded to medications of diuretics, methyldigoxin and angiotensin converting enzyme inhibitor. As congestive signs deteriorated, they became unresponsive to the treatment. Ultimately, the dogs died 9 and 13 months later from the first admission.

View full abstract

Four cytopathogenic viruses were isolated in CPK cells derived from porcine kidneys from tonsils and lungs of 3 of 15 pigs affected with porcine reproductive and respiratory syndrome virus. Physicochemically and morphologically, the isolates were similar to a coronavirus. The isolates were not distinguished from transmissible gastroenteritis virus (TGEV) by a neutralization test using polyclonal antibodies, but differentiated from TGEV by monoclonal antibodies capable of discriminating between TGEV and porcine respiratory coronavirus (PRCV), indicating that the isolates were PRCV. In a serological survey of 30 serum samples each collected from about 50 days old pigs in the 2 affected farms, 29 (97%) and 15 (50%) sera were positive for neutralizing antibody against the isolate with the titers ranging from 2 to 64, respectively.

View full abstract