Natalia M. Leonardi

In vivo iron and zinc deficiency diminished T- and B-selective mitogen stimulation of murine lymphoid cells through protein kinase C-mediated mechanism

Zinc and iron are crucial mineral components of human diet, because their deficiency leads to several disorders, including alterations of the immune function. It has been demonstrated, in both humans and rodents, that a diminished number of lymphoid cells and a loss of lymphocyte activity accompany deprivation of these essential minerals. The aim of this work was to analyze if iron and/or zinc imbalances regulate lymphocyte activity and the intracellular signals involved in the effect. Mice from the BALB/c strain were fed with iron- and/or zinc-deficient or mineral-supplemented diets, according to the American Institute of Nutrition Rodent Diets. Levels of iron and zinc were assessed in blood, liver, or bone samples. Selective mitogen stimulation of T- and B-lymphocytes were performed. We found a diminished proliferative response in T- and B-lymphocytes from zinc- and/or iron-deficient animals with respect to controls. These effects were related to decreased mitogen-induced translocation of protein kinase C (PKC) activity to cell membranes on both cell types from all animals fed with deficient diets. Our results demonstrate that iron and zinc deficiencies affect both T- and B-lymphocyte function by PKC-dependent mechanisms.

Stabilized ferrous gluconate as iron source for food fortification: bioavailability and toxicity studies in rats.

The iron bioavailability and acute oral toxicity in rats of a ferrous gluconate compound stabilized with glycine (SFG), designed for food fortification, was studied in this work by means of the prophylactic method and the Wilcoxon method, respectively. For the former studies, SFG was homogenously added to a basal diet of low iron content, reaching a final iron concentration of 20.1±2.4 mg Fe/kg diet. A reference standard diet using ferrous sulfate as an iron-fortifying source (19.0±2.1 mg Fe/kg diet) and a control diet without iron additions (9.3±1.4 mg Fe/kg diet) were prepared in the laboratory in a similar way. These diets were administered to three different groups of weaning rats during 23 d as the only type of solid nourishment. The iron bioavailability of SFG was calculated as the relationship between the mass of iron incorporated into hemoglobin during the treatment and the total iron intake per animal. This parameter resulted in 36.6±6.2% SFG, whereas a value of 35.4±8.0% was obtained for ferrous sulfate. The acute toxicological studies were performed in two groups of 70 female and 70 male Sprague-Dawley rats that were administered increasing doses of iron from SFG. The LD50 values of 1775 and 1831 mg SFG/kg body wt were obtained for female and male rats, respectively, evidencing that SFG can be considered as a safe compound from a toxicological point of view.

Determination of relative bioavailability of zinc in a petit suisse cheese using weight gain and bone zinc content in rats as markers

The aim of the study was to determine the relative bioavailability of zinc gluconate stabilized with glycine in a Petit Suisse cheese from an infant dessert. Weight gain and bone zinc content were the nutritional responses evaluated for the diets of different zinc content: 2 ppm (basal) and 5, 10, and 30 ppm from zinc gluconate stabilized with glycine and zinc sulfate. Nonlinear regression analysis of the fitted curves for weight gain determined a relative zinc bioavailability of 100% for the Ymax ratio and 96% for Ymax/t1/2 ratio for zinc gluconate stabilized with glycine (R2=0.7996 for zinc sulfate and 0.8665 for zinc gluconate stabilized with glycine). The slope ratio analysis from linear regression of femur zinc determined a relative zinc bioavailability of 93% for zinc gluconate stabilized with glycine (R2=0.8693 for zinc sulfate and 0.8307 for zinc gluconate stabilized with glycine). Zinc gluconate stabilized with glycine has similar bioavailability as zinc sulfate in a Petit Suisse cheese nutritional matrix, with the advantage that the stabilized compound does not modify the sensorial characteristics of the fortified cheese.

Normal growth rate in rats is recovered after a period of zinc deficiency by restoration of zinc supply by means of a zinc-fortified Petit Suisse cheese

Fortification of a Petit Suisse cheese with zinc sulfate and zinc gluconate stabilized with glycine was used as a tool to overcome zinc-deficiency effects on total-body growth and skeletal growth. Animals were divided in 4 groups of 10 rats: basal (B), control (C), depletion-repletion 1 (DR1), and depletion-repletion 2 (DR2). These four groups were fed with four diets: basal (2 ppm Zn), control (30 ppm Zn), DR1, and DR2; they received a basal diet for 14 d and a control diet for the other 14 d of the experiment, using zinc sulfate for DR1 and zinc gluconate stabilized with glycine for DR2. After 28 d of the experiment, total-body weight and weight gain of the control and DR1 and DR2 animals were not statistically different (p<0.05), Femur weight and femur zinc content of DR1 and DR2 did not achieve the values of control animals (p<0.05), but they were higher than that of basal animals. Our results show that restoration of dietary zinc levels by means of food fortification normalized weight gain, as an indicator of total-body growth, and presented a trend to normalize bone weight, as a marker of skeletal growth, in young rats and independently of the zinc source used.

Iron bioavailability from fortified fluid milk and petit suisse cheese determined by the prophylactic-preventive method

In this research, we measure the iron bioavailability of micronized ferric orthophosphate when it is used to fortify low-fat fluid milk enriched with calcium and petit suisse cheese using the prophylactic-preventive method in rats. Four groups of male weaned rats received a basal diet (control diet; 6.5 ppm Fe), a reference standard diet (SO4Fe; 18.2 ppm Fe), a basal diet using iron-fortified fluid milk as the iron source (milk diet; Fe ppm 17.9), and a basal diet using iron-fortified petit suisse cheese as the iron source (cheese diet; 18.0 ppm Fe) for 22 d. The iron bioavailability of the different sources was calculated as the ratio between the mass of iron incorporated into hemoglobin during the experiment and the total iron intake per animal. The relative biological values with regard to the reference standard (RBV%) were 61% and 69% for the milk and cheese diet, respectively. These results show that according to this method, the iron bioavailability in both fortified foods can be considered as medium bioavailability rates.

Radioactivity Decontamination of Materials Commonly Used as Surfaces in General-Purpose Radioisotope Laboratories

In accord with as-low-as-reasonably-achievable and good-manufacturing-practice concepts, the present study evaluated the efficiency of radioactivity decontamination of materials commonly used in laboratory surfaces and whether solvent spills on these materials affect the findings. Methods: Four materials were evaluated: stainless steel, a surface comprising one-third acrylic resin and two-thirds natural minerals, an epoxy cover, and vinyl-based multipurpose flooring. Radioactive material was eluted from a 99Mo/99mTc generator, and samples of the surfaces were control-contaminated with 37 MBq (100 μL) of this eluate. The same procedure was repeated with samples of surfaces previously treated with 4 solvents: methanol, methyl ethyl ketone, acetone, and ethanol. The wet radioactive contamination was allowed to dry and then was removed with cotton swabs soaked in soapy water. The effectiveness of decontamination was defined as the percentage of activity removed per cotton swab, and the efficacy of decontamination was defined as the total percentage of activity removed, which was obtained by summing the percentages of activity in all the swabs required to complete the decontamination. Results: Decontamination using our protocol was most effective and most efficacious for stainless steel and multipurpose flooring. Moreover, treatment with common organic solvents seemed not to affect the decontamination of these surfaces. Decontamination of the other two materials was less efficient and was interfered with by the organic solvents; there was also great variability in the overall results obtained for these other two materials. Conclusion: In expanding our laboratory, it is possible for us to select those surface materials on which our decontamination protocol works best.

Validation of a Paper Chromatographic Methodology as an Alternative for Determination of the Radiochemical Purity of Na18F

The aim of the present work was to validate a paper chromatography system as an alternative way to determine the radiochemical purity of Na18F. Methods: The evaluated parameters were specificity, limit of quantification, measurement interval, linearity, precision, accuracy, and robustness. Results: The proposed method proved to be linear (P > 0.05; r2 = 1.000), precise (relative SD, 8.6%), accurate (mean recovery, 95.9%; relative SD, 1.5%–1.8%), and robust under different conditions since no influence of the operative variables on the chromatographic performance was observed. Conclusion: This system can be used as a reliable alternative method to determine the radiochemical purity of Na18F samples that can be easily performed in PET radiopharmacies at low cost.