Dose response relationship of Haemophilus pleuropneumoniae aerosols in pigs.

The virulence of Haemophilus pleuropneumoniae was quantitated for ten and 12 week old pigs following aerosol exposure. The volume and concentration of culture aerosolized, the estimated numbers of organisms inhaled by the pigs and the mortality rates at 72 hours postexposure were computed and used to calculate the LD50. There was correlation between the concentration of culture aerosolized, the amount of the estimated inhaled dose and the mortality rates. The ten week old pigs were apparently more susceptible to aerosols of H. pleuropneumoniae than the 12 week old pigs. The LD50 value or a multiple of it appears to be a reasonable basis for a standardized aerosol challenge of the immunity of pigs vaccinated with experimental or commercial H. pleuropneumoniae vaccines.     

Propagation of the rotavirus of neonatal calf diarrhea in fetal intestinal cell cultures.

Bovine fetal intestinal cells were successfully propagated in monolayer cultures for up to 21 passages. Infection of these cells with the rotavirus of neonatal calf diarrhea resulted in a cytopathic effect that was more obvious than in infected bovine fetal kidney cells.     

Humoral and secretory antibodies to Ureaplasma diversum in heifers following subcutaneous vaccination and vaginal infection.

We measured antibody levels in serum and cervicovaginal mucus (CVM) of four heifers vaccinated with two inoculations of killed Ureaplasma diversum strain 2312 in incomplete Freund's adjuvant (IFA) two weeks apart, and six heifers given a placebo. Two weeks later, the vaccinates and four placebo heifers, were challenged by intravaginal inoculation with 6.4 x 10(8) colony-forming units of the homologous U. diversum strain. The remaining two placebo heifers served as unvaccinated, unchallenged controls. Antibody levels in serum and CVM of all heifers were determined by an enzyme-linked immunosorbent assay (ELISA). Vaccination stimulated specific IgG1 and IgG2 responses in serum and CVM but only a slight IgM and no IgA response. In both vaccinate and placebo heifers, subsequent intravaginal challenge resulted in a granular vulvitis (GV) with a predominant IgA response in the CVM. The GV gradually subsided during the 35 day observation period but ureaplasmas were consistently demonstrated by culture. We concluded that subcutaneous vaccination stimulated a specific, albeit nonprotective, IgG response in serum and CVM. In contrast, vaginal infection primarily induced a mucosal IgA response.     

Effect of left hepatic vein ligation on hepatic circulation, function, and microanatomy in dogs.

Eighteen healthy dogs were allotted to 3 groups (n = 6 dogs each). All dogs were evaluated at the beginning of the study by complete physical examination; total and differential WBC counts; serum biochemical analysis (alanine transaminase and alkaline phosphatase activities and bilirubin and albumin concentrations); sulfobromophthalein excretion, ammonia tolerance, and glucagon response testing; portal and intraparenchymal pressure determinations; operative mesenteric portography; and histologic assessment of hepatic biopsy specimens. The left hepatic vein was ligated completely in dogs of groups 1 and 2. Group-3 (control) dogs had a ligature placed loosely around the left hepatic vein. Dogs of groups 1 and 3 were reevaluated 24 hours after surgery by use of the aforementioned hematologic and biochemical tests. Group-1 dogs were reevaluated by use of portal and intraparenchymal pressure determinations, jejunal vein portography, and complete necropsy at 48 hours after surgery. At 4 weeks after surgery, dogs of groups 2 and 3 were reevaluated by use of all aforementioned tests. Results indicated transient hepatic congestion, which resolved by the fourth postoperative week. Longstanding effect on hepatic structure, circulation, or function was not found. We concluded that left hepatic vein ligation in clinically normal dogs does not cause severe or permanent liver damage.     

The value of progesterone, oestradiol benzoate and cloprostenol in controlling the timing of oestrus and ovulation in dairy cows and allowing successful fixed-time insemination

The relative merits of three hormone treatments of dairy cows: (1) intravaginally administered progesterone and oestradiol benzoate; (2) intravaginally administered progesterone and injected cloprostenol; and (3) injected cloprostenol; begun 35-75 days after calving and designed to synchronize oestrus and ovulation and allow successful artificial insemination (AI) at fixed times, have been assessed utilizing information from progesterone concentrations in milk. From this it was concluded that 89% of the cows had ovulated one to three times between calving and the beginning of treatment. Treatment (2) was more effective than (1) in synchronizing ovulation. This was due to the fact that when treatments began early in the ovulation cycle, the requirement for a rapidly effective luteolytic agent was provided by cloprostenol but not by oestradiol benzoate. Treatment (2) was also more effective than (3) in synchronizing ovulation. This is interpreted as meaning that progesterone treatment for 12 days had a beneficial effect in restoring normal cyclic ovarian function in the cows after calving. Whilst cloprostenol administered alone did not have this beneficial effect, there is no evidence that it had a detrimental effect. Based on all cows in treatment groups, the proportion that became pregnant to the fixed-time AI was significantly greater after treatment (2) than after (1), but when based on numbers of cows with synchronized ovulation, there were no significant differences among treatments in the proportions becoming pregnant. The progesterone/cloprostenol treatment had a disadvantage in that when begun during the 11-22 day period of the ovulation cycle, so resulting in a long, total period of suppression of ovulation (mean, 32.1 days), fertility to the fixed-time AI was poor despite effective synchronization of ovulation. Ovulation cycles immediately following the failed, fixed-time AI were normal, both in length and in maximum, luteal-phase progesterone concentration and indicated normal corpus luteum function. Thus the infertility could be ascribed neither to poor timing of AI nor to gross degeneration of follicles prior to their synchronized ovulation following the prolonged suppression of ovulation. The 12-day progesterone treatments when given to anovulatory cows gave, within 5.5 h of their beginning, a concentration of progesterone in milk that was not significantly different from the maximum reached. This concentration declined during the 12 days of the treatment but remained above pretreatment level until 5.5 h after treatment withdrawal; the maximum reached was about half that in normal ovulation cycles.(ABSTRACT TRUNCATED AT 400 WORDS)     

Application of amplified restriction fragment length polymorphism for genetic characterization of colletotrichum pathogens of alfalfa

ABSTRACT Amplified restriction fragment length polymorphism (AFLP) was used to assess the levels of genomic variations among species and isolates of the genus Colletotrichum. Our objective was to characterize at the molecular level two alfalfa pathogens, isolates Arl-NW and 57RR, which are unusually aggressive to anthracnose-resistant alfalfa cultivars and whose taxa has been uncertain based on morphological criteria. The fingerprint patterns obtained were complex but did enable us to place these two isolates within the species C. trifolii and C. gloeosporioides, respectively. The diversity detected with AFLP among and within Colletotrichum species from alfalfa and other crops corroborated their published taxonomy based on morphology, ribosomal DNA sequence, and random amplified polymorphic DNA analyses. Similarity matrices generated with three primer pairs were highly correlated and, thus, were combined to determine the similarity among the fungal species and isolates that were analyzed. Analysis of the data generated with each of the primer pairs individually and application of either distance or parsimony methods supported the placement of these two isolates. The parsimony method of data analysis was more confirmatory in the placement of Phoma medicaginis as an out-group than the distance method, using either simple matching or Jaccard's coefficients to generate the similarity matrices. Our conclusion is that the AFLP technique will be useful for identification of individual isolates within complex genera such as Colletotrichum because of its ability to generate large numbers of polymorphisms and the consistency of polymerase chain reaction amplification.