Use of citric acid for heavy metals extraction from contaminated sewage sludge for land application.

Recent studies revealed that organic acids such as citric and oxalic acids seemed to be more promising as chemical extracting agents for removal of heavy metals from contaminated sludge, since they are biodegradable and can attain a higher metal extraction efficiency at mildly acidic pH compared to other extracting agents. Results of a lab-scale study on the efficiency of citric acid in the extraction of chromium (Cr), copper (Cu), lead (Pb), nickel (Ni) and zinc (Zn) from anaerobically digested sludge, revealed that citric acid seemed to be highly effective in extracting Cr (at 100%), Cu (at 88%), Ni (at 98%) and Zn (at 100%) at pH 2.33, mostly at 5 days leaching time except for Cu and Zn, which are at 1 day and 2 h contact times respectively. Lead removal at the same pH was also high at 95% but at a longer leaching time of 11 days. At pH 3, citric acid seemed to be highly effective in extracting Pb (at 100%) at 1 day leaching time, although higher removals were also attained for Ni (70%) and Zn (80%) at only 2 h leaching time. Chemical speciation studies showed that Cr, Cu and Ni in the sludge sample seem to predominate in residual fractions, while Pb and Zn were found mostly bound to organic and inorganic matter forms, hence the potential of the sludge for land application.     

PCR-based procedures in detection and DNA-fingerprinting of Salmonella from samples of animal origin

The usefulness of selected PCR-protocols for the detection of Salmonella in 117 samples of animal origin (17 raw minced meat, 27 raw chicken meat, 8 raw sausages, and 25 egg samples, as well as 18 poultry faecal, and caecal swabs samples) and DNA-fingerprinting typing is shown. To establish an accurate PCR-procedure for Salmonella detection the following parameters were evaluated: two pre-PCR concentration procedures, centrifugation and immunomagnetic separation (IMS) using Dynabeads anti- Salmonella; the specificity and sensitivity of 10 sets of primers; and different conditions of the amplification reaction. In light of the results obtained from the use of PCR-based procedures alone or in combination with conventional methods, the following findings can be underlined: First, IMS is more efficient than centrifugation in the recovery of Salmonella. Second, the selected IMS/PCR-detection protocol is less time-consuming (45 h) than the IMS/culture procedure (90 h), and a good concordance between them was found when the Kappa coefficient was calculated (0·87). Third, PCR-ribotyping technique showed a very low discrimination power, being able to differentiate only three profiles. Fourth, RAPD technique using specific primers supports previous works in which it was proposed as a simple and useful tool for discriminating isolates between and within serotypes. Fifth, The efficiency, rapidity, and flexibility of the PCR-protocols applied were high, and they can be performed using two PCR-programs and the same basic equipment.     

Compulsory notification of cysticercosis in Ribeir?o Preto-SP, Brazil

Cysticercosis is a severe public health problem in several regions of Asia, Africa and Latin America. Epidemiologic studies based on the frequency of cases observed in specialized neurology, neurosurgery and computed tomography services, at autopsy and in seroepidemiologic studies do not permit the determination of the true prevalence of the disease in the population. The objective of the present study was to investigate the prevalence of cysticercosis by compulsory notification. The coefficient of prevalence was 54 cases/100,000 inhabitants in the municipality of Ribeir?o Preto. The results also indicated that cysticercosis is not under control in our region since 21% of cases presented the active form of the disease. Compulsory notification proved to be a valuable resource for the epidemiologic study of cysticercosis, also permitting the mapping of more affected areas for a better direction of prevention strategies.     

Breast-feeding and the nutritional status of nursing children in Chile

4-Pentafluoroethylumbelliferyl-beta-D-glucoside is proposed as an efficient substrate for human leukocyte acid beta-glucosidase. Its synthesis is described. This substrate was compared directly with 4-trifluoromethylumbelliferyl-beta-D-glucoside synthesized by us earlier and with 4-methylumbelliferyl-beta-D-glucoside which is commonly used for acid beta-glucosidase activity assay. The specific activity of acid beta-glucosidase with 4-pentafluoroethylumbelliferyl-beta-D-glucoside was 3- and 8-fold higher than it was with the substrates mentioned above. The kinetic parameters KM and VMAX for human leukocyte acid beta-glucosidase with the three substrates was determined. One possible application of the newly synthesized substrate is its use in the diagnosis of acid beta-glucosidase hereditary deficiency (Gaucher's disease).     

Influence of cooking and drying processes at different temperatures on the nutritive value of the protein of mussels (Mytilus edulis)

The effect of steam cooking (96 degrees C for 15 minutes) and drying at two temperatures, 70 degrees C and 110 degrees C, on nutritive value of mussel protein was studied. The measurements were carried out by nitrogen balance techniques in growing rats, and the nutritional parameters studied were: CD, BV and NPU. The crude digestibility (CD) values were: 87 +/- 1 and 82 +/- 1, and the biological values (BV), 80 +/- 1 and 74 +/- 1 for raw mussels, dried at 70 degrees C and at 110 degrees C respectively. This implies a significant decrease in the protein nutritive values of the mussel dried at a higher temperature. Cooking prior to drying significantly improved the digestibility and the biological value of the mussel's protein. In effect, improvement was so great, that the different drying temperatures did not affect the previously cooked product in a different way; therefore, the CD (94 +/- 1 and 94 +/- 1) and the BV (90 +/- 1 and 90 +/- 2) were the same for the mussel's protein, cooked and dried at 70 degrees C or at 110 degrees C.