Cost and risk analysis of heat and chemical treatments.

An economic evaluation of newly developed methods for disinfesting empty grain storage bins by heat treatment will be a useful tool for decision-making by grain storage managers. An economic empirical model of heat treatment and chemical applications was developed using minimization of costs at a target risk level associated with the grain-damaging insects Tribolium castaneum (Herbst), Sitophilus oryzae (L.), and Rhyzopertha dominica (F.). Risk was measured as a deviation below a target mortality goal (Target MOTAD). Insect mortality and air temperature during heat treatment were evaluated for empty storage bins with a full drying floor, along with a similar evaluation of insect mortality for two application rates of a contact pyrethroid insecticide, cyfluthrin 20% active ingredient (AI) wettable powder. A high-output propane heater (29 kW) had the lowest cost and risk level of all heating systems and produced 100% mortality in 2 h for the three insect species at all test locations. An electric duct-heater system (18 kW) also produced 100% mortality at all test locations after 40 h, but it had significantly higher costs. The other heating system configurations in the study had significantly higher risk levels of insect mortality, and the electric systems were not cost-effective. Both chemical rates had low costs and risk levels, with high mortality results.

Characterization of nitric oxide dependent changes in carbohydrate hepatic metabolism during septic shock.

The role of nitric oxide in the alterations of liver carbohydrate metabolism during septic shock has been studied in fed and starved animals injected with bacterial lipopolysaccharide (LPS). One h after LPS injection an hyperglycemic peak was observed followed by hypoglycemia when the plasma nitric oxide concentration increased. However, in animals pharmacologically treated with nitric oxide donors only hypoglycemia was observed. In isolated hepatocytes from LPS treated rats an impairment of the gluconeogenic flux was observed accompanied by a decrease in the mRNA levels of the glucose transporter GLUT-2 and phosphoenolpyruvate carboxykinase, at the time that increased the mRNA levels of the inducible form of nitric oxide synthase. These results suggest that part of the effects observed in response to LPS challenge are due to early signaling molecules (cytokines and other factors molecules) whereas other effects can be attributed to nitric oxide synthesis which in turn has specific effects on hepatic metabolism.