Adenohypophyseal receptors for LHRH, pituitary content of gonadotropins and plasma concentrations of LH in cyclic, pregnant and postpartum beef cows

Adenohypophyseal concentrations of LHRH receptors, pituitary content of LH and FSH, and plasma concentrations of LH were determined in thirty Hereford, Angus or Hereford-Angus heifers that were randomly assigned by breed and weight to five periods including day 3 of the estrous cycle (CY), pregnant day 120 (P120), 200 (P200), 275 (P275), or day 2 postpartum (PP). Jugular blood samples were collected at 10-min intervals for 8 hr from all cows. Within 2 hr after completion of blood sampling, animals were slaughtered and the pituitary gland frozen at −196 C. LH pulse frequency/8 hr was reduced (P<.05) during gestation (.5, .2, and 1.5 ± .5/8 hr, for P120, P200, and P275, respectively) and PP (.5 ± .5/8 hr) compared to CY (7.8 ± .5/8 hr). Frequency of LH pulses/8 hr was not different (P>.1) among P120, P200 or PP periods but was different (P<.05) between P200 and P275. There were no differences in LH pulse height (P>.1) among periods; however, pulse amplitude was greatest (P<.05) at P120 (1.3 ± .2 ng/ml) and lowest between P200 and PP (.6 to .8 ± .2 ng/ml). Baseline concentrations of plasma LH did not differ (P>.1) among P and PP periods (.3 ± .1 ng/ml), but were lower (P<.05) than in CY animals (.7 ± .1 ng/ml). Concentration of adenohypophyseal LHRH receptors was approximately two-fold greater (P<.05) at P120 (25.85 ± 2.2 fmol/mg) than at all other periods (9.5 to 14.9 ± 2.2 fmol/mg). Pituitary content of LH was greatest at P120 (1.56 ± .11 ug/mg) and lowest (P<.05) at P275 and PP (0.46 to 0.52 ± .11 ug/mg). Pituitary content of FSH was greatest (P<.05) in P (12.7 to 17.0 ± 1.4 ug/mg) and PP (18.3 ± 1.4 ug/mg) vs CY (5.0 ± 1.4 ug/mg) cows and increased from P120 to PP (P<.05). Results indicate that physiological changes occurring during gestation may have an effect on subsequent function of the adenohypophysis in beef cows.     

A radial immunodiffusion enzyme assay for detection of antibody to equine rhinopneumonitis virus (EHV-1) in horse serum

A radial immunodiffusion enzyme assay (RIDEA) was developed for detection and quantitation of antibodies to equine herpes virus-1 (EHV-1) in horse sera. The detection and quantitation of EHV-1 antibody levels were based on the diameter of the radial diffusion zone of specific antibody in each serum sample reacting with EHV-1 antigen. The circular zone was made visible using peroxidase-conjugated rabbit anti-horse immunoglobulin G and a substrate containing hydrogen peroxide. The results of the RIDEA were compared with those of virus neutralization (VN) and enzyme-linked immunosorbent assay (ELISA) and found to be highly correlated. The relative sensitivity and specificity (percentage of agreement with VN test) were found to be 98.2 and 92.5%, respectively. Because the test procedure is relatively easy to perform, the RIDEA could be used as a field test to detect antibodies to EHV-1 in horses.     

Tagging and elimination of plasmids in Salmonella of avian origin

This study compared the effectiveness of a number of procedures designed to label and eliminate plasmids that may play a role in virulence in Salmonella. Twenty strains of Salmonella of 9 serovars were subjected to 3 methods for labelling plasmids with transposons. Strains containing labelled and unlabelled plasmids were exposed to physical and chemical curing agents. Plasmids in 9 of 20 strains of Salmonella were tagged by conjugation with a donor Escherichia coli containing a temperature-sensitive RP4 plasmid that carried the Tn1 transposon. Plasmids in 2 of 5 strains of Salmonella were labelled by conjugation with a donor E. coli that contained a F' tslac::Tn5 plasmid. Transduction of Salmonella with a P22 bacteriophage that carried a temperature-sensitive Tn10 transposon resulted in chromosomal insertion of Tn10 in 2 of 10 strains. Use of chemical curing agents resulted in curing of plasmids in only 6 of 17 strains. Two strains were cured by ethidium bromide, two by a combination of ethidium bromide and novobiocin, two by a combination of imipramine and methylene blue, and none by acridine orange, novobiocin, sodium dodecyl sulfate or rifampicin. In contrast, plasmids in 14 of 17 Salmonella strains were eliminated by incubation at 45.5 degrees C.     

An evaluation of 1-hexadecylpyridinium chloride as a decontaminant in the primary isolation of Mycobacterium bovis from bovine lesions

For the primary isolation of Mycobacterium bovis from bovine lesions, 1-hexadecylpyridinium chloride (HPC) at a concentration of 0.75% was as effective as 2% NaOH in controlling the growth of contamination. The advantages of using HPC over NaOH are that it is a rapid one-step procedure not requiring neutralisation with acid, it is less toxic to M. bovis thus increasing isolation rates, and it promotes the earlier appearance of colonies.     

Monoclonal antibodies to canine adenoviruses 1 and 2 that are type-specific by virus neutralization and immunofluorescence

Monoclonal antibodies were produced against the Mirandola strain of canine adenovirus Type 1 (CAV-1) and the Manhattan strain of canine adenovirus Type 2 (CAV-2). The monoclonal antibodies were used in vitro in virus neutralization (VN) assays and in indirect fluorescent antibody (IFA) tests to examine several strains of each virus type. Out of 36 monoclonal antibodies produced against the Mirandola strain, 18 were type-specific for CAV-1 by IFA and 13 of those neutralized the virus in vitro. The other 18 antibodies bound both CAV-1 and CAV-2 by IFA; however, 7 of those specifically neutralized only CAV-1. The 160 monoclonal antibodies made against the Manhattan strain of CAV-2 yielded 77 type-specific antibodies by IFA, of which 39 neutralized only CAV-2 in vitro. The remaining 83 antibodies recognized both CAV-1 and CAV-2 by IFA, with 3 of those neutralizing both viral types. The hemagglutination inhibition (HI) test was performed on a selected monoclonal antibody from each specificity group. Although Type 1 CAV could be readily differentiated from Type 2 CAV by using type-specific monoclonal antibodies in the IFA or VN tests, strains within each type could not be differentiated. This is the first report of neutralizing monoclonal antibodies for a mammalian adenovirus.     

Feline immunodeficiency virus, feline leukaemia virus, Toxoplasma gondii, and intestinal parasitic infections in Taiwanese cats

A population consisting of 70 breeder cats, 43 clinical cases, and 16 feral cats was examined for the presence of Toxoplasma gondii, feline immunodeficiency virus (FIV), and feline leukaemia virus (FeLV). No oocysts of T. gondii were observed in 96 faecal samples; faecal samples were not available from the feral cats. Other intestinal parasites identified included Isospora felis (three cats), Isospora rivolta (five), Dipylidium canium (two), Toxocara cati (four), Toxascaris leonina (one), and Ancylostoma sp. (two). Using a kinetics-based enzyme-linked immunosorbent assay on 117 sera including all the feral cats, nine had antibody to T. gondii antigen, three for antigens to FIV, and seven to the p27 antigen of FeLV. Of the nine cats with antibody to T. gondii, only one was also infected with FIV.     

Recent advances in laboratory models for evaluation of helminth chemotherapy

Extensive research on nematodes of veterinary importance has resulted in new tests based on incubation of parasitic nematodes in culture media, with a variety of detection systems including visual observation, inhibition of aggregation, reduced secretion of acetylcholinesterase and electronic motility measurements. There has been a proliferation of tests to detect benzimidazole resistant nematodes including egg embryonation, egg hatch, larval motility, differences in esterases, and tubulin binding by labelled benzimidazoles. A simple larval development test, which detects resistance to all types of anthelmintics, is likely to become the preferred test for evaluation of resistance in nematodes of grazing animals. By contrast the relative unimportance of trematodes and cestodes from a commercial point of view has resulted in few recent developments in models for evaluating chemotherapy. But the emergence of drug resistant strains of both schistosomes and liver fluke indicates the need for simple tests to detect resistance.     

A biotyping scheme for Salmonella livingstone

Salmonella livingstone is one of the more common salmonella serotypes isolated in the United Kingdom. The characterization of 70 different isolates of S. livingstone using biochemical tests and plasmid profile analysis is described. The isolates could be divided into four groups by their ability to grow in d-tartrate, l-tartrate and Stern's glycerol. Further subdivision was achieved by the use of plasmid profile analysis; 24 of the isolates possessed light plasmids (less than 9.5 MD) and four possessed heavy plasmids (greater than 30 MD). The combination of biotyping and plasmid profile analysis can be used as the basis of a scheme to 'fingerprint' S. livingstone for epidemiological studies.     

Observations on the treatment of necrobacillosis in wallabies

Clinical experience of 73 cases of necrobacillosis in red-necked wallabies (Macropus rufogriseus) over a 6-year period is reviewed. Diagnostic methods and the medical and surgical treatment options are detailed. It is suggested that survival curves are necessary to assess the outcome of treatment.