Adenomatous polyposis coli gene large deletions in Iranian patients with familial adenomatous polyposis.

Context: Familial adenomatous polyposis (FAP) is one type of hereditary colon cancer with a large number of precancerous polyps that initiation to growth in childhood and adolescent. Mutation in adenomatous polyposis coli (APC) gene is the cause of FAP. Aims: The aim of the current study was to standardize multiplex ligation probe amplification (MLPA) method in screening of APC large deletions for the first time in Iranian patients with FAP. Subjects and Methods: Deoxyribonucleic acid was extracted from 34 FAP patients by saluting out method. All patients were screened for APC large deletions whit MLPA and for the positive results, respective region was investigated by polymerase chain reaction sequencing. All genetic alterations were doubled checked in two separated rounds of MLPA. Results: The detection rate of large fragment deletions in APC was 5.8% (2/34). Both of the Iranian patients had deletion in the middle and the end of exon 15, however, comparing of clinical features between patient with the large deletion and patients without deletion did not show any significant difference in each variable including, age at diagnosis, signs of disease and poly type. Conclusions: It seems that exon 15 of APC gene is probably the hotspot region in Iranian FAP patients. Association of genotype/phenotype is well known in FAP patients, but in this study statistical analyses did not show a significant difference in each considerable factor between patients with and without large deletions. It seems better to consider MLPA as an initial step to screening APC mutations.

Evidence for control of mercury accumulation rates in Canadian High Arctic lake sediments by variations of aquatic primary productivity.

Climate warming in the 20th Century has had profound effects on the limnology of High Arctic lakes, including substantial increases in autochthonous primary productivity (APP). Here, we report organic carbon and Hg core profiles from two lakes which support the hypothesis that 20th Century increases in sedimentary Hg at these latitudes were largely driven by APP increases, via Hg scavenging by algae and/or suspended detrital algal matter. Hydrocarbons quantitatively released by thermal cracking of algal-derived organic matter ("S2" carbon) were used to reconstruct past APP. Variation of S2 flux accounted for 87-91% of the variance in total Hg flux in the study lakes since 1854. Mercury and S2 carbon were also associated during the pre-Industrial Period, co-varying by as much as 30% during past warm/cool periods. As a test of the hypothesis, predicted values for 20th Century [Hg] were derived from pre-1900 Hg-S2 relationships. Measured 20th Century [Hg] was on average only 6-11% higher than that predicted in one lake, and 33% higher in the other. S2-normalization of [Hg] in the latter lake suggested that 78% of the average increase in 20th Century [Hg] could be explained by scavenging. These findings suggest that the atmospheric contribution of long-range anthropogenic Hg to High Arctic lakes may have been overestimated by several-fold because of this climate-driven process, and was responsible for no more than 22% of the 20th Century [Hg] increase in the study lakes.

Improved and selective platinum recovery from spent alpha-alumina supported catalysts using pretreated anionic ion exchange resin.

Improved and selective recovery of platinum from a spent dehydrogenation platinum alpha-alumina supported catalyst using a strong basic ion exchange resin is reported. Platinum and other precious metal group (PMG) complexes are leached using concentrated hydrochloric acid along with about 0.20 vol.% nitric acid as an oxidizing agent from de-coked and crushed spent catalyst. Effects of hydrochloric acid concentration, time, and temperature in leaching stage are investigated. The strong basic anionic resin is treated by sodium hydroxide solution to replace chloride anion by hydroxyl group ion. The supernatant of the leaching process is passed through a fixed column of hydroxylated strong base anionic resin. The treated resin on which the platinum complex is adsorbed is dried and burned in an oxidizing atmosphere at 750-800 degrees C. The recovered gray metallic powder is mainly platinum. Results compared with those obtained from untreated anionic resin show that adsorption of platinum complexes onto the treated anionic resin is more selective and the yield of separation is considerably improved. The breakthrough curves of the pretreated anion exchanger and that of untreated exchange resin reveals that the capacity of the hyroxilated resin is decreased by about 14%. These breakthrough curves can be used for calculation of height of a practical exchange plate (HPEP) for design purposes.

Speciation and mass-balance of mercury from pulverized coal fired power plants burning western Canadian subbituminous coals.

This report summarizes the results of a study carried out on six pulverized coal-fired power plants in western Canada burning subbituminous coal for the mass-balance and speciation of mercury. The main objectives of this study were to: determine the total gaseous mercury (TGM) emitted from stacks of power plants using the Ontario Hydro method; identify the speciation of emitted mercury such as metallic (Hg(0)) and gaseous elemental (GEM) mercury; and perform mass-balance calculations of mercury for milled-coal, bottom ash, electrostatic precipitators (ESP) fly ash and stack-emitted mercury based on three tests. Sampling of mercury was carried out using the Ontario Hydro method and mercury was determined using the USEPA method 7473 by cold vapor atomic absorption (CVAAS). The sample collection efficiencies confirmed that both oxidized and the elemental mercury had been successfully sampled at all power plants. The total gaseous mercury emitted (TGM) is 6.95-15.66 g h(-1) and is mostly in gaseous elemental mercury (GEM, Hg(0)) form. The gaseous elemental mercury is emitted at a rate of 6.59-12.62 g h(-1). Reactive gaseous mercury (RGM, Hg(2+)) is emitted at a rate of 0.34-3.68 g h(-1). The rate of emission of particulate mercury (Hg(p)) is low and is in the range 0.005-0.076 g h(-1). The range of mass-balances for each power plant is more similar to the variability in measured mercury emissions, than to the coal and ash analyses or process data. The mass-balance calculations for the six power plants, performed on results of the three tests at each power plant, are between 86% and 123%, which is acceptable and within the range 70-130%. The variation in mass-balance of mercury for the six power plants is mostly related to the variability of coal feed rate.

Monitoring the distribution and deposition of trace elements associated with a zinc-lead smelter in the Trail area, British Columbia, Canada.

The atmospheric deposition and regional dispersion pattern of the elements As, Cd, Cu, Hg, Pb and Zn, emitted from Pb-Zn smelters at Trail, British Columbia, Canada, were studied for a period of two years using the passive collection moss-monitoring method. Concentrations of these elements in moss bags, exposed to atmospheric deposition for three months, were first corrected for geogenic input and then site-specific local background level to produce common background elemental concentrations for all monitoring stations. The results of this study indicate that the deposition of these elements is greatest in proximity to the smelter and decreases with an increase in distance. The regional dispersion pattern generally varies seasonally, with the magnitude of variation being dependent on the element under study and the location of the monitoring station. Overall, the deposition of these elements (as registered by moss-monitoring stations) appears to be a complex phenomenon involving various factors such as meteorological conditions (prevailing wind direction and precipitation), physiography (topography, valley shape and orientation) and in-process activities at the smelters (production level, emission control efficiency and the geochemistry of feed). However, the results of this study indicate that, on an annual basis, in-process activities, particularly production levels of Pb and Zn and the quantity of emissions from the stack, are more directly related to the observed deposition of the elements than any of the other factors.

Monitoring the species of arsenic, chromium and nickel in milled coal, bottom ash and fly ash from a pulverized coal-fired power plant in western Canada.

The concentration of As, Cr and Ni and their speciation (As3+;5+, Cr3+;6+ and Ni0;2+) in milled coal, bottom ash and ash collected by electrostatic precipitator (ESP) from a coal fired-power plant in western Canada were determined using HGAAS, ICP-AES and XANES. The chemical fractionation of these elements was also determined by a sequential leaching procedure, using deionized water, NH4OAC and HCI as extracting agents. The leachate was analyzed by ICP-AES. Arsenic in the milled coal is mostly associated with organic matter, and 67% of this arsenic is removed by ammonium acetate. This element is totally removed from milled coal after extraction with HCI. Arsenic occurs in both the As3+ and the As5+ oxidation states in the milled coal, while virtually all (>90%) of the arsenic in bottom ash and fly ash appears to be in the less toxic arsenate (As5+) form. Both Ni and Cr in the milled coal are extracted by HCI, indicating that water can mobilize Ni and Cr in an acidic environment. The chromium is leached by water from fly ash as a result of the high pH of the water, which is induced during the leaching. Ammonium acetate removes Ni from bottom ash through an ion exchange process. Chromium in milled coal is present entirely as Cr3+, which is an essential human trace nutrient. The Cr speciation in bottom ash is a more accentuated version of the milled coal and consists mostly of the Cr3+ species. Chromium in fly ash is mostly Cr3+, with significant contamination by stainless-steel from the installation itself.

Historical variation of elements with respect to different geochemical fractions in recent sediments from Pigeon Lake, Alberta, Canada.

Geochemical analysis of elements and organic matter were conducted on vertical profiles of the recent sediments from Pigeon Lake, Alberta, Canada, to determine historical variations in elemental content of the sediments as related to their geochemical fractions. The elements are grouped according to their affinity with different geochemical fractions, by using cluster analysis and sequential extraction experiments. As a result, four elemental fractions were identified: clastic mineral detritus; carbonate; organic; and elements that show less similarity to the previous groups perhaps due to anthropogenic input or the influence of other fractions, such as oxyhydroxides. Following the identification of geochemical fractions in the sediments, a three-step normalizing method was applied using parameters that represent each geochemical fraction. These normalizing techniques appear to be important in verifying whether the variation of elements is indeed the result of anthropogenic and/or natural activities. The normalized data are correlated with the recent history of human activity and natural events near Pigeon Lake. Given the age of the lake sediments, this correlation indicates that the depth profiles of elements after being normalized to the organic and carbonate fractions reflect the variation of detrital input into the lake. However, the former mainly corresponds to the coarse-grained clastic minerals originating from high-energy erosion as the result of natural events (e.g., flooding), whereas the latter corresponds to the low-energy erosion of the fine particles (enriched in lithophile elements) due to deforestation in the drainage basin. Normalizing to the clastic mineral detritus fraction results in the increase of heavy metals in the uppermost part of the sediment profiles, which coincides with industrial activities during the past two decades in central Alberta. However, the concentration of these elements is negligible, as compared to the quantities released by geogenic processes (erosion).