<p> The study of free iron oxides in soils has for many years been an important area of research in the soil science. The development of many standard procedures over the years has free iron oxides. This study presents a systematic review of {a) the development of chemical processes and iron deposits in the podzolic group of soils, a major Canadian soil group in which free iron oxides deposits are found; {b) a review of the theory and experimental data behind some of the most widely accepted procedures of iron extraction; (c) a systematic review of four of the major methods of free iron extraction through experimental and statistical analysis employing soil samples from Thor Lake, N.W.T. The results of this study show that the most useful method for free iron oxide extraction is one that is independent of complexing variables such as pH, C.E.C., temperature and time.<p> / Thesis / Bachelor of Arts (BA)

Nitric oxide (NO) and carbon monoxide (CO) gases, alone or with oxalate, phytate, or ethylenediaminetetraacetate (EDTA) were tested for antibotulinal activity as substitutes for sodium nitrite in ground pork inoculated with spores of Clostridium botulinum, then abused by storage at 277°C. Nitric oxide with 250 ppm oxalate or phytate was most inhibitory, while NO alone was as effective as 156 ppm sodium nitrite for inhibition of gas and botulinal toxin production in the meat system. All swollen samples contained very low levels of residual nitrite, but nitroso heme and soluble iron content did not change compared with unswollen samples of the same treatment while total heme content decreased slightly. Binding iron in the meat system did not appear to be sufficient for botulinal inhibition. Apparently, residual nitrite must be present to react directly with the botulinal cell, inhibiting growth. NO gas would not be a practical subsitute for sodium nitrite in curing, since nitrite itself is formed when meat is blended in the presence of this gas. Neither could CO be used in meat curing, since the pink color of raw, CO-treated meat disappeared after cooking. More importantly, all samples treated with CO swelled rapidly and contained botulinal toxin.

Although nitrite is a known inhibitor of Clostridium botulinum in cured meats, the mechanism of inhibition is not understood. The observation has been made that iron is required for growth of C. botulinum and that the role of nitrite may be to alter the pathway of iron uptake by these organisms. Since the color change in cured meats is due to the binding of nitrite to the heme group of meat pigments, it was hypothesized that nitrite may also be tying up an essential iron source, heme. This experiment was an investigation of the possibility that myoglobin added to a meat system would stimulate growth and toxin production by C. botulinum much more than myoglobin that had been nitrosylated before inclusion in the product. Treatments were included to compare the effects of a heme iron source, myoglobin, with that of an ionic source, ferric chloride. To help understand the role of free iron in botulinal growth, several treatments contained a metal ion chlator, ethylenediaminetetraacetic acid (EDTA). Nitrite caused a definite delay of growth, as evidenced by gas bubbles, when compared with a non-nitrite system. Addition of ferric chloride resulted in an increase in the rate of of appearance of swollen samples, although growth was enhanced even more when myoglobin was added. When nitrosylated myoglobin was included, growth was inhibited more than in the treatment with nitrite alone. EDTA inhibited growth of C. botulinum but a conclusion should not be made with respect to the chelation of iron since EDTA chelates many other metals. Residual nitrite levels had declined to below 10 ppm by the time swelling occurred. Although swelling did not occur until nitrite had declined in the products, the absence of nitrite alone did not allow growth and toxin production. Since nitrosylated myoglobin and EDTA inhibited botulinal growth even after residual nitrite had declined, it is possible that the inhibitory action of nitrite is creating a nutritional deficiency for C. botulinum.

Charles University in Prague Faculty of Pharmacy in Hradec Králové Department of Biochemical Sciences Candidate: Lucie Liptáková Supervisor: RNDr. Pavlína Hašková, Ph.D. Title of master thesis: In vitro study of newly synthesized potential cardioprotective drugs Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are in an organism generated under normal or pathological conditions. There are antioxidant mechanisms, which protects the organism from their harmful effect. In case of imbalance between ROS/RNS production and antioxidant mechanisms, an oxidative stress is initiated. The oxidative stress is involved in the pathogenesis of many diseases, including cardiovascular desease. In consequence of higher presence of mitochondria and lower presence of antioxidants cardiomyocytes are more sensitive to the oxidative stress. Iron, by catalysing radical's reactions, significantly participates on formation and development of oxidative stress. Elimination of the free iron by iron chelators is one option how to prevent or moderate oxidative stress. The aim of this master theses was to study cardioprotective effect in presence of H2O2 and own toxicity of newly synthetized aroylhydrazone iron chelators (H21, H22, H23, H24, H25 and H26) on rat embryotic cardiomyoblasts H9c2. Protective and toxic...