Search PubMed⌕ Search

Biomedical subjects

S D Neill

Publications and source records attributed to S D Neill.

At least 73 records · Page 4Linked to original sources
PubMed1988

Excretion of Mycobacterium bovis by experimentally infected cattle.

Three groups, each of five calves, four to seven months old, were inoculated intranasally with different numbers of Mycobacterium bovis. Infection was established readily in the calves which received an inoculum containing either 10(6) or 10(4) colony forming units (cfu). After every infection there was a lag period during which the organisms could not be isolated from specimens of nasal mucus. All the animals excreted M bovis and the time of commencement, quantity and duration of excretion appeared to be related to the inoculation dose. Excretion continued for many weeks, and for two calves excretion became intermittent over many months. All the calves which were given inocula of 92 cfu failed to develop the disease and no immunological responses were detected; however, M bovis was isolated from nasal secretions from one of these animals 100 days after inoculation.

Animals↗
PubMed1988

A major outbreak of botulism in cattle being fed ensiled poultry litter.

Eighty of a group of 150 housed beef cattle showed classical signs of botulism after eating a batch of ensiled poultry litter. Sixty-eight of the animals died and Clostridium botulinum type C toxin was detected in 18 of 22 sera examined. C botulinum organisms were isolated from the ensiled litter and type C toxin was demonstrated in samples of decomposed poultry carcases present in the litter. This outbreak of bovine botulism was the most serious to have been recorded in Europe and was the first associated with feeding ensiled poultry litter.

Animal Feed↗
PubMed1988

The thermal stability of oligonucleotide duplexes is sequence independent in tetraalkylammonium salt solutions: application to identifying recombinant DNA clones.

In solutions of tetraalkylammonium salts the melting temperature of oligonucleotide duplexes is independent of nucleotide sequence and thus GC content. Data quantitating the destabilizing effects of various mismatches in these solvents are also presented. The results are in accord with theories on DNA melting and establish conditions under which oligonucleotides can be used as hybridization probes with predictable and controllable specificity.

Base Sequence↗
PubMed1988

Infectious agents in respiratory disease of housed, fattening lambs in Northern Ireland.

A two-year longitudinal, microbiological and pathological survey of respiratory disease in lambs housed for fattening at three-and-a-half to four months of age was undertaken. In the first year samples of nasal mucus and blood were taken from lambs each week for the first nine weeks after entry to a fattening unit and each week one lamb was examined post mortem. In the second year two additional fattening units were included in the survey, when samples of blood and nasal mucus were taken from lambs twice weekly for three weeks after entry and two lambs from each unit were examined post mortem eight to 11 days after entry to the unit. In both years the lambs had a nasal discharge and were coughing. Mycoplasma ovipneumoniae and Pasteurella haemolytica were the organisms most consistently isolated from the lungs, trachea and nasal mucus. Mycoplasma arginini and parainfluenza-3 virus were also isolated. Post mortem examination lesions of atypical, pasteurella-type and parasitic pneumonias were seen. In the second year an abattoir survey of pneumonia lesions was undertaken. Areas of pulmonary consolidation were seen in 27.5 per cent, bands of consolidation in 47.5 per cent and muellerius-type lesions in 28 per cent of the lungs examined. No significant correlation was found between the slaughter weights of the lambs and the extent of the lung lesions at slaughter.

Animals↗
PubMed1988

Mycobacterium bovis in the anterior respiratory tracts in the heads of tuberculin-reacting cattle.

Twenty-five of 50 randomly selected tuberculin-reacting cattle were confirmed as tuberculous in the laboratory. All 25 cattle had macroscopic lesions in lymph nodes associated with the respiratory tracts but only one had lung lesions. M bovis was isolated from the anterior respiratory tracts in the heads of four of the 25 tuberculous animals and from a nostril lesion found in a fifth. For at least three of these five animals, the intervals between the final tuberculin test and their previously negative tests indicated that infection had established relatively rapidly. Four of them had been tuberculin tested solely because they were animals in contiguous 'at risk' herds. It would appear that although M bovis can be isolated from the anterior respiratory tracts in the heads of tuberculin-reacting cattle, it is unlikely that primary foci of infection exist in regions other than the lungs or associated tissues. The study demonstrates the potential for reactors with lesions to excrete M bovis and the continued importance of infected cattle in the epidemiology and eradication of the disease.

Animals↗
PubMed1987

The use of aminopeptidase substrate specificity profiles to identify leptospires.

Thirty reference Leptospira strains and twelve leptospire-like cultures were examined for aminopeptidase activity using twenty-two aminoacyl-beta-naphthylamide substrates. Aminopeptidase activity was demonstrated in extracts of each of the cultures and their substrate specificity profiles compared using several computer analysis procedures. The specificity profiles were consistent for each of the strains examined. Leptospira were readily differentiated from non Leptospira strains. This was supported by DNA base ratios calculated for the strains. Of the non Leptospira strains, seven appeared similar to the "L. illini" cultured included. Two of these strains, which included the strain "L. parva" sp. nov., formed a subgroup of this "L. illini" group. Substrate specificity profiles for the L. interrogans and L. biflexa strains examined were also different from each other.

Aminopeptidases↗
PubMed1987

Retroviral vector gene expression in F9 embryonal carcinoma cells.

When F9 embryonal carcinoma (EC) cells are infected with retroviral vectors, the efficiency of expression of selectable genes is considerably lower than that in mouse fibroblasts infected with the same retroviral vectors. In this study, several retroviral vectors with regulatory sequences placed immediately 5' to a selectable gene were constructed, packaged, and used to infect mouse fibroblasts and F9 EC cells. With selection as an assay, there was a hierarchy of relative expression in F9 cells compared with that in mouse fibroblasts. These internally placed regulatory sequences are the source of the mRNAs detected in F9 EC cells, while both retroviral long-terminal-repeat promoters and internal promoters are the source of steady-state mRNAs in mouse fibroblasts. This effect was observable with both the internally placed herpes simplex virus thymidine kinase promoter and the Moloney murine leukemia virus promoter.

Animals↗
PubMed1986

Pulmonary lesions and Mycobacterium bovis excretion from the respiratory tract of tuberculin reacting cattle.

Although it is generally recognised that tuberculous lesions are present in lymph nodes associated with the respiratory tract in approximately 90 per cent of reactors with confirmed infection, lung lesions are found in only 1 to 2 per cent of such cases during abattoir examination. When lung lesions are not detected, it has been claimed that such cattle are non-excretors and thus unimportant in the epidemiology of the disease. In this study the lungs of 55 reactor cattle were sliced into sections approximately 0.5 cm thick. Tuberculous lesions were evident in over 70 per cent of lungs from reactors with concurrent lesions in lymph nodes of the respiratory system. Further, M bovis was isolated from single samples of nasal and, or, tracheal mucus taken at slaughter in 19 per cent of confirmed cases. Several of these reactors had a clear tuberculin test less than six months previously indicating recent infection. This study confirms the continued importance of the infected bovine in the epidemiology and current eradication of bovine tuberculosis. It is suggested that all tuberculous cattle with lesions in respiratory lymph nodes, rather than being regarded as non-excretors, should be considered as possible excretors and thus important sources of infection for other cattle both within and between herds.

Animals↗
PubMed1986

Bovine leptospirosis: experimental serovar hardjo infection.

Almost the full range of clinical signs observed in pregnant cattle naturally infected with Leptospira interrogans serovar hardjo was observed in this experimental study in which 22 heifers were infected by intraplacentome inoculation with serovar hardjo strains. These features included abortion, mummification, stillbirth, premature and term birth of weak calves and full-term birth of live apparently healthy calves. Leptospires were demonstrated in all but three calves by culture and or immunofluorescence.

Animals↗
PubMed1985

Aminopeptidase activity in arginine-utilizing Mycoplasma spp.

In an examination of arginine-utilizing Mycoplasma species, simple fluorogenic and chromogenic tests were used to demonstrate high levels of arginine aminopeptidase activity in unwashed, unconcentrated broth and agar cultures in all strains of 5 species and low levels of activity in all strains of 14 species. Four species contained strains which exhibited either high or low levels of activity.

Aminopeptidases↗
PubMed1985

Excretion of Leptospira interrogans serovar hardjo following calving or abortion.

Leptospira interrogans serovar hardjo was demonstrated in the vaginal discharges of 12 experimentally infected heifers for up to eight days after abortion or calving. Organisms were recovered from the oviducts of heifers examined at slaughter eight to 22 days after calving or 32 to 91 days after infection. They were also recovered from the uteri of four heifers eight to 22 days after calving.

Abortion, Veterinary↗
PubMed1984

Contagious equine metritis--use of gas liquid chromatography in identifying the causal agent.

Cellular fatty acid compositions of contagious equine metritis isolates and three reference Haemophilus equigenitalis cultures were determined by gas chromatography. The chromatographic data were standardised and normalised fatty acid methyl ester (FAME) profiles were produced. The profiles were compared visually and similarity indices were determined using a computer peak matching method. There was little difference between the profiles of the three reference strains, each strain being characterised by three major fatty acids; C 18:1, C 16:0 and 30H-C 14:0. Variations in cultural conditions had no significant effect on the FAME profiles. The identification of laboratory isolates using the technique was in agreement with the presumptive identification based on the currently recommended tests and an improvement on the confirmatory serological identification. The FAME profiles provided confirmation of identity where it was not possible to use the presently recommended serological procedures. The authors recommend the gas chromatography technique for use in the diagnostic laboratory as an adjunct to the presently accepted identification methods.

Animals↗
PubMed1983

Aminopeptidase activity of Leptospira strains.

A total of 15 cultures of Leptospira were examined for aminopeptidase activity using 22 aminoacyl-beta-naphthylamde substrates. Activity was demonstrated in each of the cultures. Extracts from serovars of Leptospira interrogans preferentially hydrolysed the same range of substrates. The level of hydrolysis of the preferred substrates for the seven strains of L. interrogans was distinctively higher than that demonstrated for the six Leptospira biflexa strains. Extracts from cultures of Leptospira illini and Leptospira parva sp. nov. exhibited profiles different to those demonstrated for the other 13 leptospiral cultures examined.

Aminopeptidases↗
PubMed1983

Leptospiral infection in aborted equine foetuses.

During an investigation of equine abortion, leptospiral infection was demonstrated in nine out of 22 foetuses examined by immunofluorescence and culture. Strains belonging to four serogroups (Australis, Pomona, Hebdomadis and Icterohaemorrhagiae) were isolated. The age of leptospira infected foetuses ranged from six months to term.

Abortion, Veterinary↗