The effect of granulosa cells on maturation, fertilization and cleavage in vitro

Addition of granulosa cells (GC) (1.10(6)/ml) affected maturation of non-ovulatory oocytes of cattle and caused delay in nuclear maturation (60.8 versus 35.3 or 37.1 percent). In vitro use of pre-incubated GC in the process of maturation led to higher rates of fertilisation (49.4 versus 25.2 or 21.0 percent) and of cleavage (29.6 versus 13.3 or 9.1 percent). No explanation has yet been found for different oocyte behaviours in response to use of fresh or pre-incubated GC. Transfer of seven embryos from maturation with GC as well as in vitro fertilisation and development to four recipients resulted in the birth of one female calf.     

Pathophysiology of the periparturient egg rise in sheep: the role of prolactin

The involvement of prolactin in the periparturient rise in the faecal nematode egg count in sheep was investigated. Ostertagia circumcincta larvae (5000 third stage larvae three times weekly) were administered to adult immune ewes from three weeks before parturition to three weeks afterwards. Ten ewes were injected twice daily with 2-bromo-alpha-ergocryptine (bromocriptine), an antagonist of prolactin secretion, for two weeks starting two days after lambing while 10 ewes remained untreated. Bromocriptine treatment was initiated approximately two weeks pre partum in three other ewes. Plasma pepsinogen concentrations rose significantly by one week after the start of O circumcincta larval challenge in all the ewes but faecal egg counts remained negative until approximately one week post partum. Plasma prolactin concentration was reduced to a very low level in all bromocriptine treated ewes but this did not alter the dynamics of the periparturient rise in faecal egg counts. Neither cell-mediated nor humoral immunity of the ewes, as assessed by their sensitivity to BCG inoculation and by antibody titre raised against horse red blood cells, respectively, were impaired during the rise in faecal egg count, nor were these parameters altered by manipulation of plasma prolactin concentration. Lamb growth rate was not retarded by low plasma prolactin concentration in the bromocriptine treated ewes. These results are not consistent with the generally held hypothesis that elevated plasma prolactin concentration is directly associated with the periparturient rise.     

Chirality of the sulphoxide metabolites of fenbendazole and albendazole in sheep

Two prochiral sulphide drugs, fenbendazole (FBZ) and albendazole (ABZ) were administered orally to sheep. Blood samples were analysed for parent drug and S-oxidation metabolites and the chirality of the sulphoxide metabolites was determined. The plasma concentrations of the enantiomers of the sulphoxides were never a racemate. On the contrary, the ratios were greater than 1 as soon as the sulphoxide compounds could be detected in plasma. They subsequently increased linearly throughout the time course of the kinetics, reaching the level 86:14 after FBZ and 95:5 after ABZ treatment. The major enantiomer represented 74% and 86% of the total AUC of SO.FBZ and SO.ABZ, respectively.     

Toxoplasmosis and other causes of abortions in sheep from north central United States

Between 1983 and 1989, we examined 1,201 aborted fetuses and dead lambs from the north central United States. Toxoplasmosis was diagnosed in 17.5%, campylobacteriosis in 9.9%, chlamydiosis in 4.7%, and miscellaneous infections in 15.1%. Inflammatory lesions suggestive of infectious causes were seen in 13%. Noninfectious causes were identified in 6.1%, and a diagnosis was not reached in 33.3%. An agglutination test was used to detect Toxoplasma gondii-specific antibodies in ovine fluids. Toxoplasma gondii antibodies were detected in 223 of 1,064 (20.9%) fluids from fetuses and dead lambs. Of 201 seropostive (greater than or equal to 16) fetuses and lambs, T gondii antibody titers (reciprocal) were 16 (21 fetuses and lambs), 32 (10 fetuses and lambs), 64 (2 fetuses and lambs), 128 (7 fetuses and lambs), 256 (9 fetuses and lambs), 512 (5 fetuses and lambs), 1,024 (15 fetuses and lambs), 2,048 (13 fetuses and lambs), 4,096 (13 fetuses and lambs), 8,196 (13 fetuses and lambs), 16,392 (19 fetuses and lambs), and greater than or equal to 32,784 (74 fetuses and lambs).     

Ultrastructural pathogenesis of the PRRS virus

Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) was first isolated in swine alveolar macrophages (SAMs) and has subsequently been reported to replicate in other cell lines. Entry of the virus inside the cell takes place by receptor-mediated endocytosis. Following the entry of the virus into the cell, several not completely understood changes take place. PRRSV has been reported to be an apoptotic-inductor virus both in vivo and in vitro. Interestingly, it has been suggested that PRRSV-induced apoptosis occurs in cells other than those in which PRRSV replicates by a bystander mechanism. In this paper the ultrastructural pathogenesis of PRRSV will be reviewed.     

Arthroscopic removal of patellar fracture fragments in horses: five cases (1989-1998)

OBJECTIVE: To evaluate the use of arthroscopy as the primary method for removal of large patellar fracture fragments. DESIGN: Retrospective study. ANIMALS: 5 performance horses of various breeds with patellar fractures. PROCEDURE: Clinical signs of lameness, external evidence of injury, and radiography were used to diagnose and determine fracture orientation. Arthroscopy of the stifle joint was performed on the affected limb with the horse positioned in dorsal recumbency and under general anesthesia. Progress after surgery was determined by evaluating medical records and via telephone conversations with owners. RESULTS: 4 of 5 horses had fractures of the medial aspect of the patella and 1 horse had a fracture of the lateral aspect of the patella. There were no postoperative complications with the joint or the arthroscopic portal incisions. Recovery periods ranged from 3 to 5 months. All horses recovered completely from surgery, and performed at the same or higher level of competition as before arthroscopy. CONCLUSIONS AND CLINICAL RELEVANCE: Femoropatellar joint arthroscopy is a favorable means by which evaluation of the stifle joint and removal of large fracture fragments can be achieved with negligible postoperative complications.     

Influence of stocking density, artificial dusk and group size on the perching behaviour of broilers

1. Perching behaviour of Ross broiler chickens was studied in order to increase the available space at the floor level. Pens (36 m2) were equipped with wooden perches mounted 20 and 33 cm above the litter (5 cm perch length per bird). 2. The influences of stocking density (22 vs 11 birds/m2, experiment 1) and of a 10 min artificial dusk (17 birds/m2, experiment 2) were tested in a 2x2 factorial design (n=4 by treatment) including control pens without perches. In experiment 3, perching behaviour between 2 different group sizes (1020 vs 4590 birds, 17 birds/m2, no replicates) was compared. 3. The percentage of perching birds (PPB) was assessed by scan sampling observations during the 20 to 22 h light period (8 observations per d, 5 d a week, from week 3). In experiment 2, infra-red video recording was performed at the time lights were dimmed and during the dark period. In experiment 1, carcase lesions were noted. In experiment 2, tibia breaking strength of frequently perching birds was compared with controls. Birds were weighed before slaughter and food conversion was calculated. 4. PPB increased with age and density (P<0.01) and was highest at the 22 birds/m2 density during week 6 (mean=10.6%, maximum=13.5%). PPB was not influenced by a 10-min artificial dusk. In experiment 3, PPB was slightly lower during weeks 5 and 6 in the large group size compared to the small group size (6.8% vs 7.9% respectively in week 6). 5. Prevalence of carcase lesions and tibia breaking strengths were unrelated to perch usage. Final body-weights were not influenced by the presence of perches except at the 22 birds/m2 density where males were slightly heavier in the control pens compared with males in pens equipped with perches (2096 g vs 2051 g, P=0.015). Food conversion was independent of the presence of perches.     

Expression of the porcine beta2-adrenergic receptor in Chinese hamster ovary cells

The gene for the porcine beta2-adrenergic receptor (pbeta2AR) was transfected into Chinese hamster ovary (CHO) cells for expression. Fourteen stable cell lines were obtained and exhibited receptor densities ranging from 12 to 2,371 fmol/mg membrane protein. The receptor density was not correlated with estimates of gene copy number obtained by Southern hybridization. The pbeta2AR in CHO cells exhibited saturable binding of [125I]CYP (Kd = 14.5 pM) and stereospecificity for (-)- and (+)-isoproterenol. The relative affinities for (-)-isoproterenol (ISO), (-)-epinephrine (EPI), and (-)-norepinephrine (NEPI) were ISO > EPI > NEPI, which are characteristic of beta2AR. The affinity values for these ligands were similar to those in other species. Binding of ISO, EPI, and NE revealed two affinity states of the betaAR; the high-affinity state was eliminated by adding Gpp(NH)p, a nonhydrolyzable GTP analogue. Binding of the antagonist propranolol modeled to only one affinity state, and Gpp(NH)p did not affect binding. Multiple affinity states are characteristic of agonist-induced coupling of betaAR with G-proteins, and the data suggest that the cloned pbetaAR is functionally competent. Data confirm that the pbeta2AR is the pig version of beta2AR. Stable CHO cell lines will be useful for characterization of pbeta2AR and screening and designing potential drugs that may be used to enhance pig production.     

The in vitro secretion of acetylcholinesterase by adult stages of Heligmosomoides polygyrus: the effects of broad-spectrum anthelmintics

The secretion of acetylcholinesterase (AChE) by female and male Heligmosomoides polygyrus was studied in different in vitro culture media. AChE secretion was increased in the presence of fetal calf serum or bovine serum albumin (BSA). In the absence of crowding effects, specific AChE activity in excretion/secretion products was higher for male (2.41 +/- 0.07 mumol min-1 l-1 mg-1) than for female (0.56 +/- 0.04 mumol min-1 mg-1) worms but on a per nematode basis both sexes showed comparable rates of secretion. Acetylthiocholine iodide was the favoured substrate of the enzyme. When the nematodes were incubated in vitro with albendazole (ABZ), ricobendazole (RBZ), mebendazole (MBZ), levamisole (LVM), morantel (MRT) or ivermectin (IVM), at concentrations from 1 mM to 10 nM, in RPMI medium for 2 or 6 h and then transferred to a drug-free medium (RPMI medium supplemented with 0.5% BSA) for 24 h or continuously exposed to the drugs in supplement-free medium (24 h), the concentration- and time-dependent inhibitory effects on AChE secretion were observed. The continued exposure to the drugs for all incubation periods (with a single exception for LVM 1 mM) produced the highest levels of inhibition. Under these conditions, the concentrations inhibiting the secretion of AChE by 50% (IC50) relative to drug-free controls were estimated. The IC50 values ranged from 0.012 microM (IVM) to 2.96 microM (MRT). The potential of this bioassay for the selective primary evaluation of new compounds with broad-spectrum anti-nematodal activity is discussed.