High prevalence of enterohemorrhagic Escherichia coli (EHEC) O157 from cattle in selected regions of Japan

The prevalence of enterohemorrhagic Escherichia coli (EHEC) O157 was examined in bovine faeces. EHEC O157 was isolated from the faeces of 42 (13.0%) of 324 cattle. Of the 4 farms and the facilities tested, the 3 farms and the facilities were found positive for EHEC O157. The highest isolation rate among the farms was 33.7%. The prevalence of EHEC O157 in heifers was higher than that in calves and other cattle. No cattle positive for EHEC O157 showed any clinical signs except 2 calves with diarrhea in a veterinary hospital. Almost all isolates possessed the stx gene, and Stx-positive strains carrying both stx(1) and stx(2) genes were predominant. These results indicate that EHEC O157 are distributed in bovine faeces, and that dairy and beef farms in selected regions of Japan are heavily contaminated with the organisms.     

Endoscopic findings on alimentary lymphoma in 7 dogs

Alimentary lymphoma was evaluated endoscopically in 7 dogs and a histopathological examination was made to detect the origin of neoplastic lymphocytes in 5 dogs. A solitary mass in the rectum (1 case), irregular cobblestone appearance in the duodenum (4 cases) and a moderate irregular appearance resembling lymphocytic-plasmacytic enteritis (2 cases) were endoscopically detected. Endoscopic ultrasonography demonstrated increased thickness of the duodenal wall in 2 cases examined. Neoplastic lymphocytes of alimentary lymphoma proved to originate in T cells in all 5 cases examined by immunohistochemical analysis.     

Expression of nerve growth factor (NGF), and its receptors trkA and p75 in ovaries of the cyclic golden hamster (Mesocricetus auratus) and the regulation of their production by luteinizing hormone

In the present study, changes in localization of nerve growth factor (NGF) and its receptors, trkA and p75 in the ovary were investigated during the estrous cycle of the golden hamster. The effect of LH surge on changes in localization of NGF, trkA and p75 in the ovary was also investigated. NGF and its receptors trkA and p75 were localized in oocytes, granulosa cells and theca cells of various stages of follicles throughout the estrous cycle. NGF and its two receptors were also present in numerous interstitial cells and luteal cells. The number of interstitial cells staining positively for NGF and its two receptors was greater in ovaries of day 1 (day 1=day of ovulation) than the other days during the estrous cycle. Treatment with the antiserum against luteinizing hormone releasing hormone (LHRH-AS) at 1100 h on day 4 completely blocked ovulation. There were few positive reactions for NGF and its two receptors in interstitial cells 24 hr after LHRH-AS injection. The effect of LHRH-AS treatment was blocked by a single injection of 10 IU human chorionic gonadotropin. The distinct widespread distribution of NGF and its two receptors in the ovary of golden hamsters suggest that NGF may be an important growth factor for regulation of ovarian function. Furthermore, the LH surge may be an important factor for inducing production of NGF and its two receptors in interstitial cells of the cyclic golden hamster.     

In vitro culture of mouse preantral follicles using membrane inserts and developmental competence of in vitro ovulated oocytes

To develop a reliable follicle culture system, mouse preantral follicles 150-200 microm in diameter were cultured individually for 5 or 6 days in membrane inserts or in droplets, and then induced to ovulate with hCG (Experiment 1). The nuclear maturation and developmental competence of the oocytes that ovulated from the follicles cultured in inserts were determined (Experiment 2). There was no significant difference between the two culture systems in the survival rate (83 and 77%). However, follicles cultured in inserts showed a higher ovulation rate (63%) than those cultured in droplets (39%, P<0.05). About 80% of the oocytes that ovulated from the follicles cultured in inserts were at the metaphase II stage. After in vitro fertilization, 75 and 48% of in vitro ovulated oocytes cleaved and developed into blastocysts, respectively. These results demonstrate that the insert culture system is superior to the droplet culture system in terms of follicular growth and ovulation, and can be used to investigate the growth and ovulation of follicles in vitro.     

The development of a sensitive enzyme immunoassay for the determination of estrone and estradiol-17beta in bovine blood plasma based on the same homologous combination with antiserum and steroid-enzyme conjugate

The development of a sensitive enzymeimmunoassay (EIA) for the determination of estrone (E1) and estradiol-17beta (E2 beta) in bovine plasma is described. The assay is a homologous double-antibody EIA with E2beta 17hemisuccinate (HS) as hapten for the immunoreactive reagent. The antiserum was raised against E2beta 17HS bovine serum albumin conjugate in the rabbit, and E2beta 17HS-horseradish peroxidase was used as steroid-enzyme conjugate. Each estrogen EIA was distinguished only by using the each working standard and sample for the EIA. Bovine plasma E1 and E2beta were extracted and purified before EIA. The antiserum was used at 1:1,750,000 dilutions for EIA. Estrone and E2beta showed high cross-reactivity with the antiserum (E1: 350.7%, E2beta:100%). The sensitivities were <0.03 pg/well for E1 and <0.12 pg/well for E2beta. Recovery rates of E1 and E2beta added to bovine blood plasma were 94.5% and 93.9%, respectively. The precision for EIA of estrogens was below 9.7%. The profiles of either estrogen as determined by EIA corresponded closely well with follicle dynamics in the cow during the estrous cycles and with placental function in pregnant animals. In conclusion, our new EIA can be applied with sufficient sensitivities, recovery and precision for the routine analysis of E1 and E2beta concentrations in bovine plasma.     

Testicular compensatory hypertrophy related to hemicastration in prepubertal dogs

Several studies have reported that the plasma testosterone (T) level and semen volume are compensated after hemicastration (HEC) in adult dogs, but that the sperm count is not. Nevertheless, the effects of HEC in prepubertal dogs have not been reported. In this study, HEC was performed at 16 weeks of age in 8 male beagles, and the function of the residual testis was investigated until 48 weeks of age. The testis volume was consistently higher in the HEC group than the control (CON) group. After 40 weeks of age, compensatory hypertrophy was observed, with a mean testis volume of 125% of that in the CON group (p<0.05). Furthermore, the semen volume and plasma testosterone (T) level were similar to those in the CON group, suggesting functional compensation, but the sperm count was not compensated. These results showed that the testis volume, semen volume, and plasma T level were compensated after HEC in prepubertal dogs, but the spermatogenic function was not.     

Molecular cloning and sequencing of the cDNA encoding the feline FcgammaRIIIA (CD16) homologue

We amplified the cDNA encoding the feline FcgammaRIIIA (CD16) homologue from peripheral blood mononuclear cells by polymerase chain reaction and cloned two forms of FCGR3A cDNA. Sequencing analysis revealed that the open reading frame of feline FCGR3A cDNA consists of 750 or 747 base pairs encoding 250 or 249 amino acid residues, respectively. Comparison of the predicted amino acid sequence of feline FCGR3A cDNA with those of other mammalians' homologues revealed that the extracellular domain has a relatively low homology. However, the cytoplasmic domain contained an 8-amino acid motif, Leu-Phe-Val-Val-Asp-Thr-Gly-Leu, which was considered to interact with an accessory molecule such as the gamma chain of Fc receptors for IgE to form heterodimeric complexes.