Vegetables, eaten fresh or boiled, are an important diet relished in many local Nigerian cuisines and delicacies. Increasing their production has therefore become a prime focus of governments in Nigeria. In the process of production, metals capable of impairing the health of consumers are inadvertently picked up. Studies were therefore conducted to determine the presence of cadmium (Cd), lead (Pb) and mercury (Hg) in fresh and boiled leafy vegetables grown in farms close (proximal) to highways (PS) and those distant from highways (DS). Composite samples of fresh lettuce (Lactuca sativa), fresh Amaranthus (Amaranthus speciosa), boiled A. speciosa, soil, irrigation water, and manure from farms located at the two sites were analyzed by Atomic Absorption Spectrophotometry (AAS). The results show that the fresh vegetables grown on sites close to highways (PS) had higher levels of Cd and Pb (0.313 microg g(-1), 16.933 microg g(-1) for Cd and Pb respectively in fresh Amaranthus, and 0.877 microg g(-1), 16.833 microg g(-1) for Cd and Pb respectively in Raw Lettuce) than those from DS farms (0.20 microg g(-1), 8.33 microg g(-1) for Cd and Pb respectively in fresh Amaranthus and 0.266 microg g(-1), 8.00 microg g(-1) for Cd and Pb respectively in Raw Lettuce). The irrigation water at the PS farms contained more Pb but similar levels of Cd and Hg. Soil from the PS was slightly more acidic (pH = 6.32 + 0.08) than those from the DS (pH = 6.49 + 0.02). Soils of PS farms gave very high Pb levels (4.13 microg g(-1)). Boiling had an effect on the levels of Cd and Pb but not Hg in Amaranthus, irrespective of the site of production. Cadmium (Cd) increased from 0.2 microg g(-1) to 1.036 microg g(-1) before and after boiling respectively in DS samples, while it increased from 0.3131 microg g(-1) to 1.037 microg g(-1) in samples from PS farms before and after boiling respectively. The level followed similar trend. Pb increased from 8.33 microg g(-1) to 5.667 microg g(-1) before and after boiling respectively in samples from DS whereas it decreased from 16.933 microg g(-1) to 14.20 microg g(-1) before and after boiling respectively in samples from the PS.

The pH values of both cooked and uncooked ogi and koko samples were determined and the survival rate of four diarrhoeagenic agents, enteroinvasive Escherichia coli, Salmonella typhi, Shigella flexneri, and Vibrio cholerae were studied after they were seeded into cooked ogi and koko. Analysis of the pH of the cooked inoculated samples showed that there was a slight increase in pH (decrease in acidity) during storage for 48 h and 37 degrees C (from 3.5 to 3.7 for ogi and from 3.7 to 4.1 for koko). The study also showed that ogi had a slightly lower pH value than koko both before and after cooking. In both cases, the cooked samples had a slightly lower pH value than the uncooked samples. The pH value of ogi ranged from 3.0 to 3.6 and that of koko from 3.5 to 3.9. The survival experiment showed that the inoculated enteric pathogens were inhibited in cooked ogi and koko during storage for 24-48 h. The antibacterial effect of cooked koko was more pronounced, on the four enteric pathogens studied, than that of cooked ogi. Except for Shigella flexneri and E. coli in ogi, non of the other bacteria studied was recovered after 24 h.

This study aims to determine the ability of zinc sulphate to inhibit growth of Shigella in vitro and test the hypothesis that the isolates recovered from Nigerian children with low plasma zinc concentration are more sensitive than the marginal plasma zinc isolates. The effect of zinc sulphate on extracellular protease secretion was also investigated. A total of 15 Shigella isolates recovered from the stool samples of 117 diarrheic children at various health centers in Lagos, Nigeria were tested for sensitivity to zinc sulphate in vitro by agar dilution method. Plasma zinc concentration was determined spectrophotometrically to enable stratification of the patients into two zinc arms: low (plasma zinc <9.2 ?mol/L) and marginal (plasma zinc: 9.2?4 ?mol/L). The in vitro effect of zinc sulphate on extracellular protease secretion based on azocasein hydrolysis in these isolates was also determined. Isolates of Shigella dysenteriae and Shigella flexneri were found to be more sensitive to zinc sulphate (minimum inhibitory concentration = 0.89?0.98 ? 0.03?0.06 mg/mL) than the isolates of Shigella sonnei and Shigella boydii (minimum inhibitory concentration = 1.13?1.4 ? 0.06?0.1 mg/mL (P < 0.05). The late logarithmic growth kinetics of these isolates also produced similar response to zinc sulphate in vitro. The observed zinc sulphate-induced growth inhibition of the Shigella isolates tested was further found to be associated with a decline in their extracellular protease secretion in both zinc arms. Zinc sulphate elicits in vitro inhibition of growth and serogroups-dependent decline in extracellular protease activity among Shigella isolates from Nigerian children irrespective of their systemic zinc levels. We conclude that zinc sulphate may have potentials to be used as a shigellocidal and anti-virulent agent in the management of shigellosis in children.