Influence of alumina on mineralogy and environmental properties of zinc-copper smelting slags

An iron-silicate slag, from a zinc-copper smelting process, and mixtures of this slag with 5wt%, 10wt%, and 15wt% alumina addition were re-melted, semi-rapidly solidified, and characterized using scanning electron microscopy equipped with energy dispersive spectroscopy, and X-ray diffraction. The FactSageTM6.2 thermodynamic package was applied to compare the stable phases at equilibrium conditions with experimental characterization. A standard European leaching test was also carried out for all samples to investigate the changes in leaching behaviour because of the addition of alumina. Results show that the commonly reported phases for slags from copper and zinc production processes (olivine, pyroxene, and spinel) are the major constituents of the current samples. A correlation can be seen between mineralogical characteristics and leaching behaviours. The sample with 10wt% alumina addition, which contains high amounts of spinels and lower amounts of the other soluble phases, shows the lowest leachabilities for most of the elements.     

Small,novel proteins from the mistletoe <Emphasis Type="Italic">Phoradendron tomentosum</Emphasis> exhibit highly selective cytotoxicity to human breast cancer cells

Four novel proteins (phoratoxins C–F) have been isolated from the North American mistletoe Phoradendron tomentosum. The amino acid sequences of these phoratoxins were determined unambiguously using a combination of Edman degradation and trypsin enzymatic digestion, and by electrospray ionization tandem mass spectrometry sequencing. Phoratoxins C, E and F consist of 46 amino acid residues; and phoratoxin D of 41. All proteins had six cysteines, similar to the earlier described phoratoxins A and B, which are thionins. The cytotoxicity of each protein was evaluated in a human cell line panel that represented several cytotoxic drug-resistance mechanisms. For the half-maximal inhibitory concentrations (IC₅₀ values) of the different cell lines in the panel, correlation with those of standard drugs was low. The most potent cytotoxic phoratoxin C was further tested on primary cultures of human tumor cells from patients. The solid tumor samples from breast cancer cells were 18 times more sensitive to phoratoxin C than the tested hematological tumor samples. Received 30 September 2002; received after revision 28 October 2002; accepted 7 November 2002 RID="*" ID="*"Corresponding author.     

Leukotrienes are potent constrictors of human bronchi

Slow reacting substance of anaphylaxis (SRS-A) is released by various stimuli, including immunological challenge, and has long been considered an important mediator of immediate hypersensitivity reactions, such as bronchoconstriction in allergic asthma. Recently, slow reacting substances from several tissues have been identified and characterized as members of a newly discovered group of substances, the leukotrienes. Leukotrienes are generated from arachidonic acid and other polyunsaturated fatty acids in a pathway initially involving a lipoxygenase-catalysed oxygenation at C-5 (Fig. 1). This differs from the synthesis of prostaglandins and thromboxanes, where the initial transformation of arachidonic acid is catalysed by a cyclo oxygenase (Fig. 1). Recently, leukotriene C4(LTC4:5(S)-hydroxy,6(R)-S-glutathionyl-7,9-trans, 11,14-cis-eicosatetraenoic acid) and D4(LTD4:5(S)-hydroxy,6(R)-S-cysteinyl-glycyl-7,9-trans,11,14-cis-eicosatetraenoic acid) were found to have biological effects in several bioassay systems, which are strikingly similar to those previously reported for impure extracts of SRS-A. Here we report the remarkable contractile activity of both LTC4 and LTD4 on isolated human bronchi, which further emphasizes the possibility that leukotrienes are potent mediators of bronchoconstriction in man.     

Retrospective determination of radon in houses

In the 1970s it was statistically proved that exposure to radon daughter products caused lung cancer in miners. High concentrations of radon daughters have since been found in houses. Any epidemiological radon study begun today is hampered because relevant exposure data are difficult to obtain owing to the long latency period between exposure and tumour manifestation. Here I present a method for measuring cumulative radon daughter levels, which takes advantage of the fact that the first long-lived radon daughter (210Pb, half-life 22 yr) becomes firmly attached to glass surfaces in a house. By measuring the surface activity concentration of the alpha-emitter 210Po, the time-integrated radon, or radon daughter, concentration can be estimated. Thus, indoor glass can act as a long-term retrospective or prospective exposure meter for radon in dwellings.