Herbicide safety relative to common targets in plants and mammals     

Shaner DL 《Pest management science》2004,60(1):17-24

Most modern herbicides have low mammalian toxicity. One of the reasons for this safety is that the target site for the herbicides is not often present in mammals. There are approximately 20 mechanisms of action that have been elucidated for herbicides. Of these, some do share common target sites with mammals. The mechanisms include formation of free radicals, protoporphyrinogen oxidase (PROTOX), glutamine synthetase (GS) and 4-hydroxyphenylpyruvate dioxygenase (HPPD). PROTOX, HPPD and GS inhibitors have been shown to inhibit these enzymes in both plants and mammals and there are measurable effects in mammalian systems. However, the consequences of inhibiting a common target site in plants can be quite different than in animals. What may be a lethal event in plants, eg inhibition of HPPD, can have a beneficial effect in mammals, eg treatment for tyrosinemia type I. These chemicals also have low mammalian toxicity due to rapid metabolism and/or excretion of the herbicide from mammalian systems.  相似文献   

Learning and teaching innovations in the veterinary undergraduate curriculum at Glasgow     

Dale VH  Johnston PE  Sullivan M 《Journal of veterinary medical education》2003,30(3):221-225

  相似文献   

Prevention of persistent infection in calves by vaccination of dams with noncytopathic type-1 modified-live bovine viral diarrhea virus prior to breeding     

Dean HJ  Hunsaker BD  Bailey OD  Wasmoen T 《American journal of veterinary research》2003,64(5):530-537

OBJECTIVE: To determine the ability of a modified-live virus (MLV) bovine viral diarrhea virus (BVDV) type 1 (BVDV1) vaccine administered to heifers prior to breeding to stimulate protective immunity that would block transmission of virulent heterologous BVDV during gestation, thus preventing persistent infection of a fetus. ANIMAL: 40 crossbred Angus heifers that were 15 to 18 months old and seronegative for BVDV and 36 calves born to those heifers. PROCEDURE: Heifers were randomly assigned to control (n = 13) or vaccinated (27) groups. The control group was administered a multivalent vaccine where-in the BVDV component had been omitted. The vaccinated heifers were administered a single dose of vaccine (IM or SC) containing MLV BVDV1 (WRL strain). All vaccinated and control heifers were maintained in pastures and exposed to BVDV-negative bulls 21 days later. Thirty-five heifers were confirmed pregnant and were challenge exposed at 55 to 100 days of gestation by IV administration of virulent BVDV1 (7443 strain). RESULTS: All control heifers were viremic following challenge exposure, and calves born to control heifers were persistently infected with BVDV. Viremia was not detected in the vaccinated heifers, and 92% of calves born to vaccinated heifers were not persistently infected with BVDV. CONCLUSIONS AND CLINICAL RELEVANCE: These results document that vaccination with BVDV1 strain WRL protects fetuses from infection with heterologous virulent BVDV1.  相似文献   

Patterns of mycoplasma shedding in the milk of dairy cows with intramammary mycoplasma infection     

Biddle MK  Fox LK  Hancock DD 《Journal of the American Veterinary Medical Association》2003,223(8):1163-1166

OBJECTIVE: To determine patterns of mycoplasma shedding in the milk of dairy cows with intramammary mycoplasma infection. DESIGN: Prospective clinical trial. ANIMALS: 10 Holstein cows with intramammary mycoplasma infection. PROCEDURE: Milk samples were collected from each cow daily for 28 days and plated on mycoplasma agar to evaluate shedding patterns. To determine whether enrichment improved recovery of organisms, some samples were also inoculated in mycoplasma enrichment medium and incubated for 4 days prior to plating. Somatic cell count (SCC) was determined in samples collected weekly. RESULTS: Mycoplasma organisms were not isolated from 81 of 280 (29%) composite milk samples, but > 10(6) colonies/mL were obtained from 151 (54%). Similarly, mycoplasma organisms were not isolated from 433 of 1,008 (43%) quarter milk samples, but > 10(6) colonies/mL were obtained from 392 (39%). For 71 of 104 (68%) samples, mycoplasma organisms were isolated both following direct plating and following enrichment; for 24 of 104 (23%), mycoplasma organisms were isolated only following enrichment; and for 9 of 104 (9%), mycoplasma organisms were isolated only after direct plating. There was a linear correlation between logarithm of the SCC and logarithm of the number of colony-forming units of mycoplasma per milliliter of milk for composite and quarter milk samples. CONCLUSIONS AND CLINICAL RELEVANCE: Shedding of organisms was inconsistent in dairy cows with intramammary mycoplasma infection, increasing the risk of misdiagnosis if multiple milk samples are not tested.  相似文献   

Harlequin ichthyosis in two greater kudu (Tragelaphus strepsiceros)     

Chittick EJ  Olivry T  Dalldorf F  Wright J  Dale BA  Wolfe BA 《Veterinary pathology》2002,39(6):751-756

Two greater kudu calves (Tragelaphus strepsiceros) born 7 years apart were found with fissures and thickened, scaly, cutaneous plates covering over 80% of their bodies. One was dead at presentation, and the other was euthanized shortly after birth. Both animals shared a common sire. On necropsy, chemosis, ectropion, eclabium, and bilateral valgus deformities of the tarsal joints were observed in one calf, presumed to be secondary to the plates restricting normal fetal development. The principal microscopic lesion was severe lamellar orthokeratosis, with focal mild parakeratosis. Ultrastructural epidermal lesions included the absence of normal lamellar granules, large dilated endoplasmic reticulum, and abnormal retention of organelles and vesicles. Gross, histopathologic, and electron microscopic findings in both kudu calves were consistent with those of harlequin ichthyosis, a rare dermatosis of humans believed to have an autosomal recessive inheritance pattern. The underlying genetic and molecular abnormality and heritability of this condition in this greater kudu herd were not determined.  相似文献   

Using the world wide web to develop key professional skills in veterinary undergraduates     

Dale VH 《Journal of veterinary medical education》2002,29(4):231-240

This paper outlines the pedagogical and practical reasons for developing two interactive online pathology modules for use by third-year undergraduates in veterinary medicine at the University of Glasgow: namely, to further students' understanding of general and systems pathology, as well as their acquisition of key professional skills, and to provide access to a core-elective system of education and to subsequent employment and lifelong learning.  相似文献   

Using focus groups for continuing veterinary medical education needs assessment and program planning     

Moore DA  Klingborg DJ  Brenner JS  Gotz AA 《Journal of veterinary medical education》2002,29(2):101-104

Needs assessments are essential to educational program development. Methods of needs assessment include environmental scans, surveys, and focus groups. Focus groups are valuable and acceptable tools to identify learner needs. The method is a qualitative research technique that is most useful to identify the range of opinions or ideas on a topic. The purposes of this paper are to explore the literature in focus groups for continuing education research, to provide information on the reasons and methods to conduct focus groups, and to present findings of participants' views of the focus group process.  相似文献   

Possible recombination of tomato-infecting begomoviruses in Thailand     

Sopid Sawangjit  Orawan Chatchawankanphanich  Pissawan Chiemsombat  Tipvadee Attathom  James Dale  Supat Attathom 《Journal of General Plant Pathology》2005,71(4):314-318

Nucleotide sequences of the three distinct Tomato yellow leaf curl Thailand virus (TYLCTHV) strains (CM, NK, SK) were analyzed for recombination events. Recombination detection program analyses and a sequence alignment survey provided evidence of recombination between AC1 sequences of TYLCV, TYLCTHV-[MM], and TYLCTHV-[NK] as major parents and of ToLCLV, ToLCTWV, and TYLCTHV-[SK] as minor parents of TYLCTHV-[NK], -[SK], -[CM], respectively. The results further support the notion that interspecies recombination may play a significant role in geminivirus diversity and their emergence as important pathogens.  相似文献   

Taenia taeniaeformis: effectiveness of staining oncospheres is related to both temperature of treatment and molecular weight of dyes utilized     

Chapalamadugu KC  Busboom JR  Nelson ML  Hancock DD  Tang J  Jasmer DP 《Veterinary parasitology》2008,151(2-4):203-211

Methods to determine viability of taeniid oncospheres following treatments with potential lethality have practical application in efforts to control transmission. Here we investigated several methods, in lieu of infectivity studies, to assess oncosphere viability and determine lethal temperature treatment regimens. In the first experiment, a standard treatment to exshell oncospheres with 0.5% hypochlorite was assessed for influence on oncosphere recovery of Taenia taeniaeformis eggs. Recovery of eggs and exshelled oncospheres decreased with increasing time in hypochlorite, which indicated that hypochlorite can damage eggs and oncospheres, translating into potential overestimation of lethality of experimental treatments. Losses in hypochlorite were accentuated when eggs were pretreated at 75 degrees C, but not lower temperatures, including 65 degrees C, indicating a sharp threshhold between 65 degrees C and 75 degrees C where eggs and oncospheres became hypersensitive to subsequent hypochlorite treatment. To further investigate this change in relation to temperature, non-vital (acridine orange, AO) and vital (propidium iodide, PI; trypan blue, TB) dyes were used to assess staining of oncospheres (exshelled or not) under conditions ranging from room temperature up to 95 degrees C. The behaviors of dyes as related to internal staining of oncospheres were described using non-linear regression and a sigmoid four-parametric model to determine the inflection point (T50). Each of the dyes differed significantly in T50 estimates, e.g. AO (69.22+/-0.53), PI (73.89+/-0.52) and TB (79.43+/-0.45). For these dyes, the T50 increased in relation to the increasing molecular weight of the dyes. Collectively, the results suggested that barriers to chemical permeability exist in eggs that breakdown incrementally with increasing temperatures above 65 degrees C. This staining behavior and the likelihood that the temperatures involved are above a lethal threshhold clarify a basic limitation in the use of vital dyes to assess oncosphere viability. The results may be relevant to other Taenia spp.  相似文献   

SAMOATM: one company's approach to herbicide-resistant weed management     

Dale L. Shaner  David A. Feist  E. James Retzinger 《Pest management science》1997,51(3):367-370

SAMOA (Second Active Mode of Action) is a program that was developed by American Cyanamid as a way to prevent/delay selection of resistance to the imidazolinones and to manage resistant weed populations if they are selected. The program consisted of three major components, all of which had to be implemented for the program to be successful. These components comprised educating sales persons, distributors and farmers on resistance management, developing efficacious and cost-effective tank mixtures or sequential programs and providing incentives for using this program. ©1997 SCI  相似文献