Modelling the contamination of lettuce with Escherichia coli O157:H7 from manure-amended soil and the effect of intervention strategies

Aims: A growing number of foodborne illnesses has been associated with the consumption of fresh produce. In this study, the probability of lettuce contamination with Escherichia coli O157:H7 from manure-amended soil and the effect of intervention strategies was determined. Methods and Results: Pathogen prevalence and densities were modelled probabilistically through the primary production chain of lettuce (manure, manure-amended soil and lettuce). The model estimated an average of 0·34 contaminated heads per hectare. A minimum manure storage time of 30 days and a minimum fertilization-to-planting interval of 60 days was most successful in reducing the risk. Some specific organic farming practices concerning manure and soil management were found to be risk reducing. Conclusions: Certain specific organic farming practices reduced the likelihood of contamination. This cannot be generalized to organic production as a whole. However, the conclusion is relevant for areas like the Netherlands where there is high use of manure in both organic and conventional vegetable production. Significance and Impact of the Study: Recent vegetable-associated disease outbreaks stress the importance of a safe vegetable production chain. The present study contributed to this by providing a first estimate of the likelihood of lettuce contamination with E. coli O157:H7 and the effectiveness of risk mitigation strategies.     

Peroxidation of lipids from liver mitochondria during pneumonia

Inflammation of the respiratory system leads to an increase in the relative content of lipids in the liver mitochondria and to an activation of initial stages of their peroxidation. Antioxidative activity of the postmitochondrial liver fraction is in the inverse relation to the concentration of acyl residues with the conjugated diene structures. But the malonic dialdehyde level decreases during the lung inflammation development from 3 days to 3 months. These changes may be explained by respiratory mitochondria chain reconstruction due to an increase in the lipid utilization in the oxidative phosphorylation reactions.     

Preparation of bioindicators for controlling the efficacy of sterilization processes

A test microbe for the control of the efficacy of vacuum steam sterilization was selected. Conditions for the spore cultivation were developed. The optimal bioindicator composition, test microbe loading, nutrient medium, pH indicator, carbohydrates and a carrier were defined.     

Effects of oxymethacil on microcirculation and neuronal impulse activity in the cat cerebral cortex in acute fosfakol poisoning]

By using the methods of vital microscopy and extracellular registration of the neuronal activity the effect of oxymethacil (OM) on microcirculation and NSA in cat brain cortex was studied after grave poisoning by organophosphate paraoxon. The rapid depression of NSA together with the pronounced disturbances of microcirculation in cortical vessels were showed after intravenous injection of paraoxon (0.8 mg/kg). The prophylactic injection of OM (5 mg/kg) induced protective effect on the studied parameters. This effect was more pronounced when OM injection was combined with the M-cholinolytic amyzyl. The present data show the reasonableness of antioxidants using for the correction of a brain functional condition damaged by organophosphates.     

Electrogenicity at the donor/acceptor sides of cyanobacterial photosystem I

To study electrogenesis the photosystem I particles fromSynechococcus elongatus were incorporated into asolectin liposomes, and fast kinetics of laser flash-induced electric potential difference generation has been measured by a direct electrometric method in proteoliposomes adsorbed on a phospholipid-impregnated collodion film. The photoelectric response has been found to involve three electrogenic stages associated with (i) iron-sulfur center F_x reduction by the primary electron donor P700, (ii) electron transfer between iron-sulfur centers F_x and F_A/F_B, and (iii) reduction of photo-oxidized P700⁺ by reduced cytochromec ₅₅₃. The relative magnitudes of phases (ii) and (iii) comprised about 20% of phase (i).