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J R Stokes

Publications and source records attributed to J R Stokes.

7 recordsLinked to original sources
PubMed2002

Producer breeding objectives and optimal sire selection.

Information from an online survey of dairy producers was used to determine how important producers perceived three different objectives in the breeding problem. The objectives were: maximizing expected net merit of the progeny, minimizing the expected progeny inbreeding coefficient, and minimizing semen expenditure. Producers were asked to rank the three objectives and then to weight the importance of each objective relative to the others. This information was then used to determine weights to be used in a multiple-objective integer program designed to select individual mates for a herd of 76 Jersey cows with known genetic background and cow net merit. The results of the multiple-objective models show that rank and relative importance of producer objectives can affect the portfolio of sires selected. Producers whose primary objective was to maximize expected net merit had a range of average expected progeny net merit of $306 to $310, but the level of expected progeny inbreeding was from 6.99 to 10.45%, with a semen cost per conception of $35 to $41. For producers who selected minimizing progeny inbreeding as the primary goal in their breeding programs, the range of inbreeding was from 6.11 to 6.60%, with lower net merit range of $274 to $301 and semen expenditure of $30 to $37 per conception. One producer selected minimizing semen cost as the primary objective. For that producer's portfolio, the semen cost was $27 per conception and net merit was $288, with a progeny inbreeding coefficient of 10.68%. The results of this research suggest that producer information and goals have a substantial impact on the portfolio of sires selected by that producer to attain these goals.

Animals↗
PubMed2001

Using multiple objective programming in a dairy cow breeding program.

Multiple-objective programming was used to examine the effects various objectives had on the optimal portfolio of sires chosen for a given breeding problem in a Jersey cow dairy herd. It was assumed that the dairy producer had the following three objectives in the breeding decision: to maximize Net Merit, to minimize inbreeding, and to minimize total expenditure on semen. Integer programming models of these three single objectives were estimated to provide the ideal and anti-ideal values for use in several multiple-objective programming models. The integer multiple-objective models examined the interactions and costs of tradeoffs between the three single objectives in a model framework designed to minimize the maximum deviations from the single-objective optima. A model with equal weights on each objective resulted in a decrease of 3% in average inbreeding but also reduced average Net Merit by $170 from the single-objective optima. A second model, where the weight on Net Merit was twice that of inbreeding and semen cost, decreased Net Merit by $100 and reduced inbreeding by 2% from the single objective optima. The results of the multiple-objective programming models show that reducing the inbreeding coefficient for a group of sires purchased will decrease the Net Merit. However, the results generated also demonstrate that the weights placed on each objective by the dairy producer substantially affect the optimal levels of each objective within the multiple-objective model.

Algorithms↗
PubMed2000

Cannabis (hemp) positive skin tests and respiratory symptoms.

BACKGROUND: We have noted several patients who had rhinitis and/or asthma symptoms when exposed to Cannabis plants in the summer months. Cannabis plants are common in the Midwest. OBJECTIVES: To examine whether Cannabis might be a clinically important allergen, we determined Cannabis pollination patterns in the Omaha area for 5 years, the prevalence of skin test positivity, and the association with respiratory symptoms. METHODS: Airborne Cannabis (and other weed) pollens were collected using a Rotorod air impactor, and pollen counts were done using a standardized protocol. RESULTS: Measurable Cannabis pollen count was not recorded until the last 2 weeks of July. Peak pollination typically occurred during mid- to late-August, and comprised up to 36% of the total pollen counts. Cannabis pollen was not observed after mid-September. To determine the prevalence of skin test positivity, we added Cannabis to the multi-test routine skin test battery. Seventy-eight of 127 patients tested (61%) were skin test positive. Thirty of the 78 patients were randomly selected to determine if they had allergic rhinitis and/or asthma symptoms during the Cannabis pollination period. By history, 22 (73%) claimed respiratory symptoms in the July through September period. All 22 of these subjects were also skin test positive to weeds pollinating during the same period as Cannabis (ragweed, pigweed, cocklebur, Russian thistle, marsh elder, or kochia). CONCLUSIONS: The strong association between skin test reactivity, respiratory symptoms, and pollination period suggests that Cannabis could be a clinically important aeroallergen for certain patients and should be further studied.

Air Pollutants↗
PubMed1998

Attenuation of virus-induced airway dysfunction in rats treated with imiquimod.

Viral respiratory infections cause acute airway abnormalities consisting of inflammation and physiological dysfunction in both animals and humans. It is likely that inflammatory cell products, such as cytokines, contribute substantially to viral-induced airway dysfunction. We hypothesized that imiquimod, an immune response enhancing agent that induces interferon-alpha, would attenuate the development of airway dysfunction during acute viral illness in rats. Adult Brown Norway rats were inoculated with parainfluenza type 1 (Sendai) virus or sterile vehicle, and treated with either imiquimod or water. Respiratory system resistance (Rrs), arterial oxygen tension (Pa,O2), lung viral titres and bronchoalveolar lavage (BAL) leucocyte counts were measured in anaesthetized, paralysed, ventilated rats. Virus-infected, water-treated rats had a significant decrease in Pa,O2 and had significant increases in leucocyte count and Rrs when compared to both the virus-infected, imiquimod-treated, (Pa,O2, p = 0.03; leucocyte count, p = 0.02; and Rrs, p = 0.009) and noninfected, water-treated rats (Pa,O2, p = 0.007; leucocyte count, p = 0.001; and Rrs, p = 0.01). In addition, imiquimod suppressed BAL eosinophils in both virus-infected (p = 0.02) and noninfected (p = 0.001) groups, and lowered overall virus titres (p = 0.03). Thus, both virus-induced airway inflammation and physiological dysfunction were attenuated significantly by imiquimod treatment in this animal model. By further delineating mechanisms by which infections induce airway dysfunction in animal models, more specific pharmacological interventions can be developed for the treatment of virus-induced asthma.

Adjuvants, Immunologic↗
PubMed1997

The bridging bronchus. Successful diagnosis and repair.

Anomalies of bronchial branching are infrequent and may be difficult to diagnose. The bridging bronchus is a rarely reported anomaly that may not be as sporadic as once thought. We describe an infant with respiratory distress whose right middle and lower lobes were supplied by a bridging bronchus arising from the left main bronchus. The airway anatomy was defined using flexible and rigid bronchoscopy and helical computed tomographic scanning, enabling successful surgical repair. We review current literature on the bridging bronchus as well as the possible embryological basis for this defect.

Bronchi↗