Actin polymerization enhances Pasteurella haemolytica leukotoxicity     

Basaraba RJ  Byerly AN  Mosier DA  Butine MD  Stewart GC  Fenwick BW  Chengappa MM  Highlander SK 《Veterinary microbiology》1999,64(4):307-321

Pasteurella haemolytica leukotoxin is cytotoxic to bovine leukocytes, causing increased cell membrane permeability, osmotic swelling, release of cytosolic proteins and cell lysis. These studies were designed to test if leukotoxin causes release of the cytoskeletal protein, actin, from bovine leukemia cells and if purified actin-influenced bacterial growth or leukotoxin production. Culture supernatants caused a 7-fold decrease in viability of bovine leukemia cells and increased cell permeability that was accompanied by release of beta-actin into the cell culture supernatant. Exposing P. haemolytica to purified actin solutions induced the conversion of monomeric G-actin to polymerized F-actin. This conversion was partially inhibited by bovine P. haemolytica immune, but not pre-immune, serum. Loss of streptomycin resistance following treatment of the organism with acridine orange ablated the polymerizing activity. Incubation of P. haemolytica in the presence of purified F-actin did not affect growth but resulted in culture supernatant that had 3.0-3.9-fold greater leukotoxicity compared to medium alone or medium containing G-actin, heat-denatured actin or albumin. The effect of actin on leukotoxicity was concentration-dependent and directly associated with increases in secreted leukotoxin. The interaction between P. haemolytica and actin is potentially detrimental to the host by inducing polymerization of actin into insoluble filaments and by enhancing leukotoxicity.  相似文献   

A moluccan cockatoo with disseminated cryptococcosis     

B Fenwick  K Takeshita  A Wong 《Journal of the American Veterinary Medical Association》1985,187(11):1218-1219

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Salmonella Brandenburg in non-pregnant 8-month-old sheep     

Clark RG  Swanney S  Hogan MC  Marchant RM  Fenwick SG 《New Zealand veterinary journal》1999,47(6):210

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A case of bovine mastitis caused by Bacillus cereus     

Parkinson TJ  Merrall M  Fenwick SG 《New Zealand veterinary journal》1999,47(4):151-152

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PARTURIENT PARESIS (MILK FEVER) OF COWS: 7. Pre-treatment Heart Rates   总被引：1，自引：0，他引：1  

D. C. Fenwick  B.V.Sc. 《Australian veterinary journal》1969,45(10):456-457

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PARTURIENT PARESIS (MILK FEVER) OF COWS: 2. The Quantity of Calcium Solution used in Treatment and Changes in Heart Beat Characteristics     

D. C. Fenwick  B.V.Sc. 《Australian veterinary journal》1969,45(3):114-117

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Human recombinant interleukin-2 augments in vitro blastogenesis of bovine and porcine lymphocytes   总被引：2，自引：0，他引：2  

J L Stott  B W Fenwick  B I Osburn 《Veterinary immunology and immunopathology》1986,13(1-2):31-38

The recent cloning of the human gene encoding interleukin 2 (IL-2) has provided the means for economical production of large quantities of the pure lymphokine for clinical studies. Human recombinant interleukin 2 (HrIL-2) has been reported to have in vitro and in vivo immunomodulating effects in the murine system, suggesting the cloned gene product has cross-species activity. Bovine and porcine peripheral blood lymphocytes were tested for responsiveness to HrIL-2 in a lymphocyte blastogenesis assay. Not only was the HrIL-2 highly stimulatory but it also reconstituted lymphocyte responsiveness to maximal values following incubation with suboptimal concentrations of mitogen plus exogenous lymphokine. These studies suggest that HrIL-2 has the potential of serving as an in vivo modulator of immunoresponsiveness in domestic species. The contribution to food animal medicine will be considerable if administration of the lymphokine results in augmentation of antigen-specific immune responses when applied as an adjuvant, non-specific booster of pre-existing immunity, or for therapy of immunosuppression.  相似文献   

PARTURIENT PARESIS (MILK FEVER) OF COWS: 4. Rectal Temperature   总被引：1，自引：0，他引：1  

D. C. Fenwick  B.V.Sc. 《Australian veterinary journal》1969,45(3):123-126

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Pulmonary Mycobacterium bovis infection in a dog     

Gay G  Burbidge HM  Bennett P  Fenwick SG  Dupont C  Murray A  Alley MR 《New Zealand veterinary journal》2000,48(3):78-81

AIM: To describe the clinical course of a dog infected with Mycobacterium bovis causing a granulomatous pneumonia. CLINICAL FINDINGS: The dog initially presented with a persistent cough, inappetence and weight loss. Clinical findings included a fever, dyspnoea and tachypnoea, with haematological evidence of a mild neutrophilia and hypoalbuminaemia. Radiographs of the chest demonstrated a concomitant pneumothorax, pleural effusion, and a consolidated area within the left caudal lung lobe. An exploratory thoracotomy revealed this to be a ruptured granulomatous lesion. Subsequent histopathological, microbiological and genetic studies identified M. bovis as the causal agent. CLINICAL SIGNIFICANCE: Mycobacterium bovis infections should be included in the differential diagnosis of pulmonary disease and pleural effusions in dogs living in regions of New Zealand known to have a high incidence of mycobacterial infection in wildlife and farm animals.  相似文献   

Transmission of Brucella ovis from rams to red deer stags     

Ridler AL  West DM  Stafford KJ  Wilson PR  Fenwick SG 《New Zealand veterinary journal》2000,48(2):57-59

AIM: To determine whether B. ovis will transmit from infected rams to non-infected red deer stags (Cervus elaphus) grazing together in the same paddock. METHODS: Six rams artificially infected with B. ovis were grazed with six non-infected 14-month-old red deer stags for a four and a half month period from March 4 to July 20, 1999. Stags were blood sampled at one- to six-weekly intervals to test for B. ovis antibodies using a complement fixation test. Stags that seroconverted were semen sampled to test for B. ovis infection by bacteriological culture. RESULTS: Between day 92 and day 124 of grazing together (June 4 and July 6), sera from five of the six stags became positive in the B. ovis complement fixation test. B. ovis was cultured from semen samples from four of the seropositive stags. CONCLUSIONS: Brucella ovis can be transmitted from infected rams to non-infected stags grazing in the same paddock, suggesting that B. ovis infection in farmed deer in New Zealand initially came from infected rams. Whether transmission occurs from direct contact between rams or stags, or indirectly by environmental contamination needs to be established.  相似文献