Bovine abortion associated with infectious bovine rhinotracheitis virus infection     

D P Stubbings  I R Cameron 《The Veterinary record》1981,108(5):101-102

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Immunization of mice and calves against Salmonella dublin with attenuated live and inactivated vaccines.     

C M Cameron  W J Fuls 《The Onderstepoort journal of veterinary research》1976,43(2):31-37

Previous findings, viz. that mice can be successfully immunized against infection with Salmonella dublin with either live or inactivated vaccine, were confirmed. Immunity lasted for at least 12 weeks in mice which had been immunized with inactivated alum-precipitated vaccine. The immunogenicity of inactivated vaccine gradually decreased on storage at 4 degrees C, but this was only detectable if a single injection was used for immunization: 2 injections virtually eliminated this phenomenon. The immunogenicity of live vaccine in mice was not enhanced by levamizole or the simultaneous injection of inactivated organisms. Both live and inactivated vaccines provided immunity in calves. A single injection of lyophilized vaccine, prepared from live rough Salmonella dublin strain (HB 1/17),protected 3 out of 6 calves, while 2 injections of a formalin-inactivated, alum-precipated vaccine, containing 1% packed cells of S. dublin strain 2652 V, protected 5 out of 6 calves against intraduodenal challenge with 2 x 10(9), S. dublin strain 2652 V. Two calves which had been immunized with an inactivated oil adjuvant vaccine were also solidly immune to this challenge. Serum antibody response in calves was poor when measured by the tube agglutination and the haemagglutination tests. Similarly, the sera had only marginal protective values when tested by means of a passive protection test in mice. Antibody titres alone are not a valid measure therefore, for the immune status of immunized animals.  相似文献   

A laboratory device for producing single drops in uniform sizes of 150–450 μm diameter     

Colin R. Merritt  John A. Drinkwater 《Pest management science》1977,8(5):457-462

A device is described which can produce single drops of liquids in uniform sizes. Drop size can be adjusted, and with an aqueous solution of a non-ionic surfactant (“Agral”; 1 ml/litre) sizes 160–490 μm diam. were produced. Suitable techniques of calibration are given. The device is a useful research tool for study of the effects of form of deposit on herbicide performance.  相似文献   

Parotid salivary duct rupture and fistula in the dog and cat     

Colin E. Harvey 《The Journal of small animal practice》1977,18(3):163-168

Three dogs and one cat were diagnosed at the University of Pennsylvania Veterinary Hospital as having parotid salivary duct rupture and fistula as a result of previous surgery. Sialography confirmed the diagnosis. Two animals were treated by ligation, and two by anastomosis of the parotid duct. All four animals returned to normal after treatment.  相似文献   

Effects of skirting on processing characteristics of Targhee wool.     

R W Kott  R H Stobart  C M Hoaglund  C L Johnson  B A Cameron  V M Thomas 《Journal of animal science》1992,70(3):640-645

Ninety mature Targhee ewes were randomly allocated to nine lots. Lots were randomly assigned to three fleece preparation treatments: 1) nonskirted (control); 2) bellies removed, in which bellies and topknots were removed on the shearing floor; and 3) skirted, in which bellies and topknots were removed and remaining fleece was thrown on a table and lightly skirted. Bellies and topknots composed about 6 to 7% of the fleece weight. An additional 6.6% was removed when fleeces were skirted. Top fiber diameters were not affected (P greater than .10) by skirting. Although not significant (P greater than .10), percentage yield, vegetable content, percentage of noilage, top fiber length, and yellowness indexes tended to be most desirable for skirted lots and least desirable for unskirted lots. Lots with bellies removed were intermediate. Removal of bellies reduced vegetable contamination by 8.4%, with an additional reduction of about .5% by further skirting. Skirting reduced the number of fibers less than 25.4 mm (P less than .10) by 42%. Minimal colored fiber contamination of top was observed. One colored fiber per 15 g of top was detected in two lots of the treatment with bellies removed. All other lots contained no colored fibers. All wools evaluated were well below industry limits set for use in high-quality white or pastel fabrics. All skirted lots of wool evaluated in this study had improved processing characteristics for all processing traits evaluated.  相似文献   

Immune response of merino sheep to inactivated Corynebacterium pseudotuberculosis vaccine   总被引：1，自引：0，他引：1  

C M Cameron  J L Minnaar  M M Engelbrecht  M R Purdom 《The Onderstepoort journal of veterinary research》1972,39(1):11-24

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Immunological and chemical characteristics of Corynebacterium pseudotuberculosis cell walls and protoplasm     

C M Cameron  M R Purdom 《The Onderstepoort journal of veterinary research》1971,38(2):83-92

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Financial and organizational support needed to expand veterinary pathology training programs     

Harris RK  Rousseaux CG 《Veterinary clinical pathology / American Society for Veterinary Clinical Pathology》2005,34(3):178-178

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Production of eosinophil chemoattractant activity by ovine gastrointestinal nematodes     

Wildblood LA  Kerr K  Clark DA  Cameron A  Turner DG  Jones DG 《Veterinary immunology and immunopathology》2005,107(1-2):57-65

Eosinophilia is a well documented feature of helminth infections but the precise nature of the interaction between parasite and eosinophil remains an enigma. This paper describes experiments demonstrating that ruminant gastrointestinal trichostrongyles produce potent chemoattractant activity for ovine bone marrow-derived eosinophils in vitro. This activity was initially identified as a constituent of whole worm extracts of third and fourth larval (L3, L4), and adult stages of Teladorsagia circumcincta, and adult Haemonchus contortus. Similar activity was detected in excretory/secretory (E/S) material derived from live T. circumcincta L3. Subsequently, by adapting the assay technique to incorporate live worms directly into the system, it was shown that L3 of both T. circumcincta and H. contortus produced eosinophil chemoattractant activity. In contrast, neither whole worm extracts, or E/S preparations from mixed stages of the free-living nematode Caenorhabditis elegans contained eosinophil chemoattractant activity, and there was no evidence of chemoattractant production by live C. elegans. The results described are challenging to the traditional dogma that eosinophils are host-protective effector cells, and raise the intriguing possibility that ovine nematodes actively encourage recruitment of eosinophils. Local eosinophil-mediated mucosal damage, comparable to that seen in the asthmatic lung, may then provide a permissive local microenvironment for the parasite. Moreover, if they prove important for pathogenicity, nematode chemoattractants could offer future potential as novel therapeutic targets.  相似文献   

The host-parasite relationship in bovine neosporosis     

Innes EA  Wright S  Bartley P  Maley S  Macaldowie C  Esteban-Redondo I  Buxton D 《Veterinary immunology and immunopathology》2005,108(1-2):29-36

Infection with the protozoan parasite Neospora caninum is thought to be a major cause of reproductive failure in cattle worldwide. Cattle infected with the parasite are three to seven times more likely to abort compared to uninfected cattle. The parasite may be transmitted to cattle through the ingestion of oocysts that are shed in the faeces of acutely infected dogs (definitive host of N. caninum) or by congenital infection from mother to foetus via the placenta. Interestingly, transplacental transmission can occur over consecutive pregnancies and congenitally infected heifers can transmit the parasite to their own offspring. This repeated vertical transmission observed in naturally infected cattle suggests that cattle do not easily develop effective immunity to the parasite, presenting a significant challenge to the development of a control strategy based on vaccination. Neosporosis is a disease of pregnancy and studying the bovine maternal and foetal immune responses during pregnancy will help us to understand the change in the balance between the parasite and the host that may result in disease of the foetus. Studies in non-pregnant cattle and in murine models of infection have shown the importance of T-helper 1-type immune responses involving pro-inflammatory cytokines, such as IFNgamma and IL-12, in limiting intracellular multiplication of the parasite. During pregnancy, changes occur in the immune system allowing the mother to accept the foetal allograft. Research in other species has stressed the crucial role of T-helper 2-type cytokines at the materno-foetal interface in maintaining the pregnancy and regulating the potentially damaging effect of Th-1 responses. Studies in cattle have shown that cell proliferation and IFNgamma responses may be significantly down-regulated around mid-gestation. This may mean that cattle are less able to cope with N. caninum infection at this time and are more likely to transmit the parasite to the foetus. Another important factor is the gestational age and hence immuno-competence of the foetus at the time of infection. Early in gestation, N. caninum infection of the placenta and subsequently the foetus usually proves fatal, whereas infection occurring in mid to late pregnancy may result in the birth of a congenitally infected but otherwise healthy calf. Studies of foetal immune responses have shown that at 14 weeks of gestation, lymphocytes only respond to mitogen, while by 24 weeks (mid-gestation), they respond to antigen by proliferating and releasing IFNgamma. Clearly, there are several factors influencing the outcome of N. caninum infection in pregnancy: the timing, quantity and duration of parasitaemia, the effectiveness of the maternal immune response and the ability of the foetus to mount an immune response against the parasite. The challenge is to design a vaccine that will prevent foetal infection by N. caninum. This is likely to involve a fine balancing act with the immune system that will allow intervention in a manner that will tip the host-parasite balance in favour of the host without compromising the pregnancy.  相似文献