Cross-sectional study of hepatic CYP1A and CYP3A enzymes in hybrid striped bass, channel catfish and Nile tilapia following oxytetracycline treatment   总被引：1，自引：0，他引：1  

Topic Popovic N  Howell T  Babish JG  Bowser PR 《Research in veterinary science》2012,92(2):283-291

Terramycin for Fish® (oxytetracycline, OTC) is one of three approved drugs for therapeutic treatment of fish in the United States. Nothing is known, however, of the effects of this therapeutic on drug metabolizing enzymes in fish post-treatment. The main purpose of the study was to examine whether the fish CYP1A and CYP3A enzymes would cross-react with antibodies to known mammalian cytochrome P-450 forms (CYP1A1 and CYP3A). Observational feeding studies of OTC effects were conducted in hybrid striped bass, channel catfish and Nile tilapia. Oxytetracycline was mixed into the feed to achieve a daily dose of 82.8 mg per kg body weight at a feeding rate of 1% body weight per day. Hepatic microsomes of each fish were prepared and Western blotting of CYP1A1 and CYP3A4 and enzyme assays of CYP1A2 and CYP3A4 were performed prior to OTC treatment and on post-treatment days 1, 6, 11 and 21. Both goat anti-rat CYP1A1 and rabbit anti-human CYP3A4 showed good cross-reactivity with all three species in this study. All three species exhibited distinct perturbations in one or more of the variables examined on day 1 post-treatment. Immediately following the 10-day medication period, relative liver weight (RLW) of hybrid striped bass was increased 44% and remained elevated through post-treatment day 21. Increased CYP3A4 enzyme activity and protein abundance were noted in channel catfish and Nile tilapia, respectively. This observational approach demonstrated species differences both in control activities and in the timing and extent of hepatic responses to OTC. The unique perturbations of hepatic CYP450 enzymes in different fish species to OTC treatment observed in this study may have relevance for the use of additional antibiotics or other therapeutics used in aquaculture.  相似文献   

Seasonality,floods and droughts structure larval fish assemblages in prairie rivers          下载免费PDF全文

Crystal Garcia  David A. Schumann  Jessica Howell  Brian D.S. Graeb  Katie N. Bertrand  Robert A. Klumb 《Ecology of Freshwater Fish》2018,27(1):389-397

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The influence of breed,age, gender,training level and ambient temperature on forelimb and back temperature in racehorses          下载免费PDF全文

Maria Soroko  Kevin Howell  Krzysztof Dudek  Radomir Henklewski  Paulina Zielińska 《Animal Science Journal》2017,88(2):347-355

A previous thermographic study of racehorses identified 13 regions of interest (ROIs) for monitoring the impact of training. However, that investigation did not consider the influence of breed, age, gender or training intensity level on the temperature of ROIs. The present study adopted a multivariate analysis approach to determine whether the aforementioned factors, along with ambient temperature, significantly influenced ROI temperature in the key body regions. Thermography measurements were obtained from 53 racehorses of three breeds. Horses were in regular training for over 10 months, having 13 thermographic examinations in each racing season. Backward stepwise multiple linear regression indicated that ambient temperature and breed contributed significantly to the model for predicting ROI temperature at all 13 ROIs. Training intensity level contributed significantly to the model only at the thoracic vertebrae, the left third metacarpal bone and left fetlock joint. Neither gender nor age contributed to the model significantly at any ROI. Our data suggest that ambient temperature, breed and training level affect racehorse body surface temperature in some areas of the distal parts of the forelimbs and the back. This contributes to a better understanding of the normal range of thermographic findings in racehorses undergoing intensive training.  相似文献   

Cranberry proanthocyanidins induce apoptosis and inhibit acid-induced proliferation of human esophageal adenocarcinoma cells     

Kresty LA  Howell AB  Baird M 《Journal of agricultural and food chemistry》2008,56(3):676-680

The occurrence of esophageal adenocarcinoma and its only recognized precursor lesion, Barrett's esophagus, has rapidly increased during the past three decades. The precise reason for the rise remains to be elucidated, but increasing rates have been linked to multiple nutritional factors. Plant-based diets have generally been associated with a reduction of risk for esophageal adenocarcinoma and those of animal origin with risk escalation. Moreover, a number of recent in vitro and limited in vivo investigations have reported that cranberry extracts affect multiple cancer-associated processes in breast, colon, prostate, and other cancer cell lines of epithelial origin. Thus, this study sought to investigate the chemopreventive potential of a cranberry proanthocyanidin rich extract (PAC) in SEG-1 human esophageal adenocarcinoma (EAC) cells. PAC pretreatment significantly inhibited the viability and proliferation of EAC cells in a time- and dose-dependent manner. Moreover, PAC (50 microg/mL) significantly inhibited acid-induced cell proliferation of SEG-1 cells. PAC treatment induced cell cycle arrest at the G1 checkpoint and significantly reduced the percentage of SEG-1 cells in S-phase following 24 and 48 h of exposure. PAC treatment also resulted in significant induction of apoptosis. Thus, PAC modulates cell cycle regulation, aberrant proliferation, and apoptosis, all key biological processes altered during progression to esophageal adenocarcinoma. These findings support that further mechanistic studies are warranted to more fully elucidate the inhibitory potential of PAC against esophageal cancer.  相似文献   

Possible Fenthion Toxicity in Magpies (Pica pica)          下载免费PDF全文

J. Hanson  J. Howell 《The Canadian veterinary journal. La revue veterinaire canadienne》1981,22(1):18-19

Unusual mortality in magpies (Pica pica) is described. Dead or sick birds were discovered in proximity to cattle in Alberta feedlots. Subsequent examinations indicated magpies were being exposed to fenthion, an organophosphate used on cattle for control of warble larvae and lice. The possibility of toxicity with fenthion is suggested.  相似文献   

West Nile virus infection of Thoroughbred horses in South Africa (2000-2001)     

Guthrie AJ  Howell PG  Gardner IA  Swanepoel RE  Nurton JP  Harper CK  Pardini A  Groenewald D  Visage CW  Hedges JF  Balasuriya UB  Cornel AJ  MacLachlan NJ 《Equine veterinary journal》2003,35(6):601-605

REASONS FOR PERFORMING STUDY: West Nile virus (WNV) infection is endemic in southern Africa. With the recent emergence of WNV infection of horses in Europe and the USA the present study was performed to estimate the risk of seroconversion to WNV in a cohort of 488 young Thoroughbred (TB) horses. OBJECTIVES: To estimate the risk of seroconversion to WNV among a cohort of South African TB yearlings sold at the 2001 National Yearling Sales (NYS) and to determine whether the risk varied geographically. Two horses were also infected with a recent South African isolate of WNV to evaluate its virulence in horses. METHODS: Serum samples were collected from the cohort of 488 TB yearlings at the 2001 NYS. Serum samples that were collected from the same horses at the time that they were identified were sourced from our serum bank. Sera from 243 of the dams that were collected at the time that the foals were identified were also sourced from our serum bank. These sera were subjected to serum neutralisation (SN) tests for antibody to WNV. RESULTS: Approximately 11% of yearlings seroconverted to WNV on paired serum samples collected from each animal approximately 12 months apart. Studfarms with WNV-seropositive yearlings were widely distributed throughout South Africa and SN tests on sera from their dams indicated that exposure to WNV was even more prevalent (75%) in this population. Neurological disease was not described in any of the horses included in this study and 2 horses inoculated with a recent lineage 2 South African isolate of WNV showed no clinical signs of disease after infection and virus was not detected in their blood. CONCLUSIONS: Infection of horses with WNV is common in South Africa, but infection is not associated with neurological disease. POTENTIAL RELEVANCE: In contrast to recent reports from Europe, North Africa, Asia and North America, the results of our field and experimental studies indicated that exposure of horses to the endemic southern African strains of WNV was not associated with neurological disease.  相似文献   

The application of improved techniques to the identification of strains of bluetongue virus   总被引：3，自引：0，他引：3  

P G Howell  N A Kümm  M J Botha 《The Onderstepoort journal of veterinary research》1970,37(1):59-66

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Histochemical study of the accumulation of copper in the liver of sheep     

J S Kumaratilake  J M Howell 《Research in veterinary science》1987,42(1):73-81

Six Merino sheep were dosed orally with a 0.2 per cent solution of copper sulphate, six others were undosed controls. Liver biopsies were obtained and stained for copper by the p-dimethylaminobenzylidene rhodanine (DMABR), rubeanic acid (RA) and ferricyanide (FCN) methods for examination by light microscopy. The initial and most marked accumulations of copper were found within the hepatocytes of the centrilobular zones. Increased copper loading resulted in copper deposition extending through the midlobular to the periportal zones. The deposition of copper was unequal between hepatocytes and with increasing copper loading isolated hepatocytes became packed with copper containing granules. Copper appeared within Kupffer cells and macrophages of portal triads. The first Kupffer cells to be positively stained and the greatest number of such cells were adjacent to the central veins. Accumulation of copper was demonstrated with hepatocytes at copper concentrations equivalent to 44.3 micrograms copper g-1 liver wet weight. The FCN method provided a more satisfactory demonstration of intracellular copper than the RA technique and the latter was better than the DMABR method. However, the DMABR technique provided the clearest morphological details.  相似文献   

Inclusion body hepatitis in chickens.   总被引：4，自引：1，他引：3       下载免费PDF全文

J Howell  D W MacDonald    R G Christian 《The Canadian veterinary journal. La revue veterinaire canadienne》1970,11(5):99-101

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The occurrence of Paramyxovirus yucaipa in Canadian poultry.   总被引：1，自引：0，他引：1       下载免费PDF全文

G Lang  A Gagnon    J Howell 《The Canadian veterinary journal. La revue veterinaire canadienne》1975,16(8):233-237

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