Investigating the potential role of vitamin E in modulating the immunosuppressive effects of tylvalosin and florfenicol in broiler chickens.

Tylvalosin (TVS) is a third-generation macrolide drug used for prophylaxis and treatment of mycoplasma, however; it is supposed to possess an immunosuppressive effect. In the current study, the immunosuppressive effect of TVS and florfenicol (FFC) and the potential immunomodulatory role of Vit E were investigated. The experiment included one day old chick groups treated with either TVS, FFC, Vit E, TVS/Vit E, FFC/Vit E and control non-treated group. Chicks were vaccinated with inactivated H9N2 avian influenza (AI) vaccine and humoral antibody titers to viral antigen as well as innate immunity (serum lysozyme activity and nitric oxide levels) were evaluated. Total and differential leucocytic counts, serum liver enzymes level, blood leucocytic DNA damage and cellular area percentages within the lymphoid organs were also screened. Treatment with TVS and FFC significantly decreased immune response of chickens while treatment with Vit E improved the humoral immune response at 4 and 5weeks post-vaccination. Vit E also significantly increased the cellular immune response. The combination of Vit E with either TVS or FFC modulated their immunosuppressive effect and resulted in mild immunostimulatory effects. TVS alone induced a genotoxic effect on chickens' blood leucocytes and the genotoxicity was inhibited by combination of TVS with Vit E. Histopathology revealed that chickens treated with either TVS or FFC exhibited toxic effect on the lymphatic tissues.

Combining time and intensity effects in assessing operator information-processing load.

A quantitative description of the human information processor is required for predicting operator workload and performance from the simulated task time line data generated by task network models and related methods. Although many models of workload exist, few appear to be well founded in theory or to provide a satisfactory basis for a quantitative representation of operator load. Adherents of both time- and intensity-based models of operator load individually claim success for their methods, which might suggest that both factors are operating in determining operator workload and performance. This paper describes a study that explicitly investigates the relationship between a time-based factor and an intensity-based factor (amount of information to be processed) within a simulated air traffic control environment. A model is developed that posits that the load on the human information-processing system results directly from the ratio of the time necessary to process the required information to the time allowable for making a decision. This ratio, which can be identified with time pressure, determines subjective estimates of workload as well as operator performance. The model is tested against the data from the air traffic control simulation.

Traffic and noise in children's wards.

OBJECTIVE: To measure pedestrian traffic volumes and noise levels in paediatric open bay areas and discuss their impact on the care of sick children. METHODS: Between August and October 1992, we recorded the number and duration of entrances to two open bay areas comprising eight and ten beds respectively in a ward for infants and a ward for older children. Eight 24-hour periods (1200 to 1200) Friday to Saturday were assessed. Noise levels in decibels dB(A) were measured at 15-minute intervals. RESULTS: In an average 24-hour period, 5.5 (SD +/- 1.3) patients in the infants' ward and 9.5 (SD +/- 0.6) patients in the children's ward received 617 (SD +/- 85) and 683 (SD +/- 64) visits by 104 (SD +/- 20) and 110 (SD +/- 2) individuals respectively. The maximum numbers of visits per hour were 57 (SD +/- 14) and 54 (SD +/- 8) visits between 1500 and 1600 hours on Friday for each ward. Visits tended to be brief; 225 (SD +/- 23) and 217 (SD +/- 34) visits were of less than one minute's duration. The maximum noise levels of 57.3 dB(A) (SD +/- 6.3) and 64.6 dB(A) (SD +/- 3.5) occurred at 1000 Saturday and 1900 Friday and coincided with peak traffic volumes. CONCLUSIONS: Open bay areas generate high traffic volumes and coincident noise. Consideration should be given to either modifying or abolishing open bay areas and to general noise control measures.