Binding intensity and metal partitioning in soils affected by mining and smelting activities in Minas Gerais, Brazil.

Mining and smelting activities are potential sources of heavy metal contamination, which pose a threat to human health and ecological systems. This study investigated single and sequential extractions of Zn, Pb, and Cd in Brazilian soils affected by mining and smelting activities. Soils from a Zn mining area (soils A, B, C, D, E, and the control soil) and a tailing from a smelting area were collected in Minas Gerais state, Brazil. The samples were subjected to single (using Mehlich I solution) and sequential extractions. The risk assessment code (RAC), the redistribution index (U ts ), and the reduced partition index (I R ) have been applied to the sequential extraction data. Zinc and Cd, in soil samples from the mining area, were found mainly associated with carbonate forms. This same pattern did not occur for Pb. Moreover, the Fe-Mn oxides and residual fractions had important contributions for Zn and Pb in those soils. For the tailing, more than 70 % of Zn and Cd were released in the exchangeable fraction, showing a much higher mobility and availability of these metals at this site, which was also supported by results of RAC and I R . These differences in terms of mobility might be due to different chemical forms of the metals in the two sites, which are attributable to natural occurrence as well as ore processing.

A maize line resistant to herbivory constitutively releases (E) -beta-caryophyllene.

Various pests, such as those in the order Lepidoptera, frequently feed on young maize (Zea mays) plants and pose a significant threat to plant development and survival. To manage this problem, maize generates a wide variety of responses to attack by pests, from activation of wound-response pathways to the release of volatile compounds. Mp708, an inbred line resistant to feeding by the larvae of the fall armyworm (Spodoptera frugiperda J.E. Smith Lepidoptera: Noctuidae), has been developed through traditional breeding methods, but its underlying mechanisms of resistance are still not completely understood. Mp708 has been shown to have a moderately high constitutive expression of jasmonic acid (JA) before infestation by fall armyworm. However, Tx601, a genotype susceptible to feeding by fall armyworm, activates JA pathway only in response to feeding, suggesting that Mp708 is "primed" to respond swiftly to an attack. Current research indicates that fall armyworm show a lack of preference to feeding on Mp708, leading to the hypothesis that volatiles constitutively released by the plant may also play an important role in its resistance. Analysis of volatiles released by Mp708 and Tx601 in the presence and absence of fall armyworm larvae identified (E)-beta-caryophyllene, a terpenoid associated with resistance, released constitutively in Mp708. Fall armyworm fed samples of both Mp708 and Tx601 showed high transcript number of tps23, the gene responsible for the synthesis of (E)-beta-caryophyllene. In addition, fall armyworm larvae show a preference for Tx601 whorl tissue over Mp708 tissue, and the dosage of Tx601 whorl with (E)-beta-caryophyllene repels the fall armyworm.

Randomized controlled trial of atorvastatin in mild to moderate Alzheimer disease: LEADe.

BACKGROUND: There is some evidence that statins may have a protective and symptomatic benefit in Alzheimer disease (AD). The LEADe study is a randomized controlled trial (RCT) evaluating the efficacy and safety of atorvastatin in patients with mild to moderate AD. METHODS: This was an international, multicenter, double-blind, randomized, parallel-group study. Subjects had mild to moderate probable AD (Mini-Mental State Examination score 13-25), were aged 50-90 years, and were taking donepezil 10 mg daily for > or 3 months prior to screening. Entry low-density lipoprotein cholesterol levels (LDL-C) were > 95 and < 195 mg/dL. Patients were randomized to atorvastatin 80 mg/day or placebo for 72 weeks followed by a double-blind, 8-week atorvastatin withdrawal phase. Coprimary endpoints were changes in cognition (Alzheimer's Disease Assessment Scale-Cognitive Subscale [ADAS-Cog]) and global function (Alzheimer's Disease Cooperative Study Clinical Global Impression of Change [ADCS-CGIC]) at 72 weeks. RESULTS: A total of 640 patients were randomized in the study. There were no significant differences in the coprimary endpoints of ADAS-cog or ADCS-CGIC or the secondary endpoints. Atorvastatin was generally well-tolerated. CONCLUSIONS: In this large-scale randomized controlled trial evaluating statin therapy as a treatment for mild to moderate Alzheimer disease, atorvastatin was not associated with significant clinical benefit over 72 weeks. This treatment was generally well-tolerated without unexpected adverse events. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that intensive lipid lowering with atorvastatin 80 mg/day in patients with mild to moderate probable Alzheimer disease (aged 50-90), taking donepezil, with low-density lipoprotein cholesterol levels between 95 and 195 mg/dL over 72 weeks does not benefit cognition (as measured by Alzheimer's Disease Assessment Scale-Cognitive Subscale) (p = 0.26) or global function (as measured by Alzheimer's Disease Cooperative Study Clinical Global Impression of Change) (p = 0.73) compared with placebo.

Quick extended x-ray absorption fine structure instrument with millisecond time scale, optimized for in situ applications.

In order to learn about in situ structural changes in materials at subseconds time scale, we have further refined the techniques of quick extended x-ray absorption fine structure (QEXAFS) and quick x-ray absorption near edge structure (XANES) spectroscopies at beamline X18B at the National Synchrotron Light Source. The channel cut Si (111) monochromator oscillation is driven through a tangential arm at 5 Hz, using a cam, dc motor, pulley, and belt system. The rubber belt between the motor and the cam damps the mechanical noise. EXAFS scan taken in 100 ms is comparable to standard data. The angle and the angular range of the monochromator can be changed to collect a full EXAFS or XANES spectrum in the energy range 4.7-40.0 KeV. The data are recorded in ascending and descending order of energy, on the fly, without any loss of beam time. The QEXAFS mechanical system is outside the vacuum system, and therefore changing the mode of operation from conventional to QEXAFS takes only a few minutes. This instrument allows the acquisition of time resolved data in a variety of systems relevant to electrochemical, photochemical, catalytic, materials, and environmental sciences.

Phospholipids block nuclear factor-kappa B and tau phosphorylation and inhibit amyloid-beta secretion in human neuroblastoma cells.

Inflammation and oxidative stress have been shown to play a critical role in the pathophysiology that leads to neurodegeneration. Omega-6 phospholipids, e.g. dilinoleoylphosphatidylcholine (DLPC), have been shown to have anti-inflammatory properties and therefore experiments were undertaken to determine whether DLPC can prevent inflammatory neurodegenerative events in the model neuronal cell line, SH-SY5Y. Tumor necrosis factor (TNF-alpha) and H(2)O(2) activate mitogen-activated protein kinase (MAPK) in SH-SY5Y cells within 5 min and this activation is completely blocked by DLPC (12 microM). DLPC blocks IkappaBalpha phosphorylation in the SH-SY5Y cells and prevents the phosphorylation and activation of nuclear factor-kappa B (NF-kappaB). The phospholipid inhibits induction of MAPK and NF-kappaB in similar fashion to the MEK1/2-inhibitor, U0126 (10 microM). DLPC completely abolishes TNF-alpha, H(2)O(2) and lipopolysaccaride (LPS)-induced neuronal tau phosphorylation. Cellular amyloid precursor protein levels are reduced by DLPC and LPS-induced amyloid-beta expression and secretion in SH-SY5Y cells are completely blocked by DLPC. Taken together, these data suggest that DLPC can act through MAPK to block neuronal inflammatory cascades and prevent potential pathological consequences in the neuronal metabolism of amyloid and tau proteins.

An ATR-FTIR spectroscopic approach for measuring rapid kinetics at the mineral/water interface.

This study presents a methodology for studying rapid kinetic reactions for IR active compounds. In soils, sediments, and groundwater systems a rapid initial chemical reaction can comprise a substantial portion of the total reaction process at the mineral/water interface. Rapid-scan attenuated total reflectance (ATR) Fourier transform infrared (FTIR) spectroscopy is presented here as a new method for collecting rapid in situ kinetic data. As an example of its application, the initial oxidation of arsenite (As III) via Mn-oxides is examined. Using a rapid-scan technique, IR spectra were collected with a time resolution of up to 2.55 s (24 scans, 8 cm(-1) resolution). Through observation and analysis of IR bands corresponding to arsenate (AsV), rapid chemically-controlled As III oxidation is observed (initial pH 6-9) with 50% of the reaction occurring within the first one min. The oxidation of As III is followed by rapid binding of AsV to HMO, at least in part, through surface bound Mn II. The experimental data indicate that rapid-scan FTIR is an effective technique for acquisition of kinetic data, providing molecular scale information for rapid reactions at the solid/liquid interface.

Peripheral ethanolamine plasmalogen deficiency: a logical causative factor in Alzheimer's disease and dementia.

Although dementia of the Alzheimer's type (DAT) is the most common form of dementia, the severity of dementia is only weakly correlated with DAT pathology. In contrast, postmortem measurements of cholinergic function and membrane ethanolamine plasmalogen (PlsEtn) content in the cortex and hippocampus correlate with the severity of dementia in DAT. Currently, the largest risk factor for DAT is age. Because the synthesis of PlsEtn occurs via a single nonredundant peroxisomal pathway that has been shown to decrease with age and PlsEtn is decreased in the DAT brain, we investigated potential relationships between serum PlsEtn levels, dementia severity, and DAT pathology. In total, serum PlsEtn levels were measured in five independent population collections comprising >400 clinically demented and >350 nondemented subjects. Circulating PlsEtn levels were observed to be significantly decreased in serum from clinically and pathologically diagnosed DAT subjects at all stages of dementia, and the severity of this decrease correlated with the severity of dementia. Furthermore, a linear regression model predicted that serum PlsEtn levels decrease years before clinical symptoms. The putative roles that PlsEtn biochemistry play in the etiology of cholinergic degeneration, amyloid accumulation, and dementia are discussed.

Hyperaccumulator Alyssum murale relies on a different metal storage mechanism for cobalt than for nickel.

The nickel (Ni) hyperaccumulator Alyssum murale has been developed as a commercial crop for phytoremediation/phytomining Ni from metal-enriched soils. Here, metal co-tolerance, accumulation and localization were investigated for A. murale exposed to metal co-contaminants. A. murale was irrigated with Ni-enriched nutrient solutions containing basal or elevated concentrations of cobalt (Co) or zinc (Zn). Metal localization and elemental associations were investigated in situ with synchrotron X-ray microfluorescence (SXRF) and computed-microtomography (CMT). A. murale hyperaccumulated Ni and Co (> 1000 microg g(-1) dry weight) from mixed-metal systems. Zinc was not hyperaccumulated. Elevated Co or Zn concentrations did not alter Ni accumulation or localization. SXRF images showed uniform Ni distribution in leaves and preferential localization of Co near leaf tips/margins. CMT images revealed that leaf epidermal tissue was enriched with Ni but devoid of Co, that Co was localized in the apoplasm of leaf ground tissue and that Co was sequestered on leaf surfaces near the tips/margins. Cobalt-rich mineral precipitate(s) form on leaves of Co-treated A. murale. Specialized biochemical processes linked with Ni (hyper)tolerance in A. murale do not confer (hyper)tolerance to Co. A. murale relies on a different metal storage mechanism for Co (exocellular sequestration) than for Ni (vacuolar sequestration).

Influence of water quality on cholesterol induced systemic pathology.

Reduced systemic pathology was identified in cholesterol-fed rabbits administered distilled water compared to animals drinking local tap water; this included pathology of the liver and spleen. Studies directed at determining the effect of the trace metals aluminum, copper and zinc on cholesterol-induced systemic pathology were undertaken. As previously reported copper added to distilled drinking water (0.12 PPM) increased Alzheimer-like pathology in the brain, but did not augment pathology of the spleen or liver. Aluminum added to distilled water (0.36 PPM) administered to drink exacerbated cholesterol-induced hepatic pathology but not splenic pathology, and addition of 0.36 PPM zinc to the distilled drinking water failed to affect pathology of either the liver or spleen. The overall increase in both central and systemic pathology observed among cholesterol-fed rabbits administered tap water seems to be due to different trace metal contaminants occurring in tap water.

Trace copper levels in the drinking water, but not zinc or aluminum influence CNS Alzheimer-like pathology.

Mounting evidence suggests copper may influence the progression of Alzheimer's disease by reducing clearance of the amyloid beta protein (Abeta) from the brain. Previous experiments show that addition of only 0.12 PPM copper (one-tenth the Environmental Protection Agency Human consumption limits) to distilled water was sufficient to precipitate the accumulation of Abeta in the brains of cholesterol-fed rabbits (1). Here we report that addition of copper to the drinking water of spontaneously hypercholesterolemic Watanabe rabbits, cholesterol-fed beagles and rabbits, PS1/APP transgenic mice produced significantly enhanced brain levels of Abeta. In contrast to the effects of copper, we found that aluminum- or zinc-ion-supplemented distilled water did not have a significant effect on brain Ab accumulation in cholesterol-fed rabbits. We also report that administration of distilled water produced a reduction in the expected accumulation of Ab in three separate animal models. Collectively, these data suggest that water quality may have a significant influence on disease progression and Ab neuropathology in AD.

Circulating cholesterol levels, apolipoprotein E genotype and dementia severity influence the benefit of atorvastatin treatment in Alzheimer's disease: results of the Alzheimer's Disease Cholesterol-Lowering Treatment (ADCLT) trial.

CONTEXT: Recent evidence suggests that treatment of mild-to-moderate Alzheimer's disease (AD) with atorvastatin provides significant benefit on the Alzheimer Disease Assessment Scale-Cognitive (ADAS-cog) after 6 months. OBJECTIVE: To determine if benefit on ADAS-cog performance produced by atorvastatin is influenced by severity of cognitive impairment, circulating cholesterol levels, or apolipoprotein E genotype. DESIGN: A double-blind, placebo-controlled, randomized (1:1) trial with a 1-year exposure to atorvastatin calcium or placebo. SETTING: A single-site study at the clinical research center of the Sun Health Research Institute. PARTICIPANTS: Ninety-eight individuals with mild-to-moderate AD (MMSE score of 12-28) provided informed consent, and 67 were randomized. Stable dose use of cholinesterase inhibitors, estrogen and vitamin E was allowed, as was the use of many other medications in the treatment of co-morbidities. Participants using cholesterol-lowering medications or being treated for major depression or a psychiatric condition were excluded. INTERVENTION: Once daily atorvastatin calcium (80 mg; two 40 mg tablets) or placebo. MAIN OUTCOME MEASURES: A primary outcome measure was change ADAS-cog sub-scale score. Secondary outcome measures included scores on the MMSE, and circulating cholesterol levels. The Apolipoprotein E genotype was established for each participant. RESULTS: A significant positive effect on ADAS-cog performance occurred after 6 months of atorvastatin therapy compared with placebo. This positive effect was more prominent among individuals entering the trial with, (i) higher MMSE scores, (ii) cholesterol levels above 200 mg/dl or (iii) if they harbored an apolipoprotein-E-4 allele compared with participants not responding to atorvastatin treatment. Individuals in the placebo group tended to experience more pronounced deterioration if their cholesterol levels exceeded 200 mg/dl or they harbored an apolipoprotein-E-4 allele. CONCLUSION: Atorvastatin therapy may be of benefit in the treatment of mild-to-moderately affected AD patients, but the level of benefit produced may be predicated on earlier treatment, an individual's apolipoprotein E genotype or whether the patient exhibits elevated cholesterol levels.

Statin therapy in Alzheimer's disease.

Previous studies have suggested that statin therapy may be of benefit in treating Alzheimer's disease (AD). We initiated a double-blind, placebo-controlled, randomized (1:1) trial with a 1-year exposure to once-daily atorvastatin calcium (80 mg; two 40 mg tablets) or placebo among individuals with mild-to-moderate AD [Mini-Mental State Examination (MMSE) score of 12-28]. Stable dose use of cholinesterase inhibitors, estrogen and vitamin E was allowed, as was the use of most other medications in the treatment of co-morbidities. We demonstrated that atorvastatin treatment produced significantly (P = 0.003) improved performance on cognition and memory after 6 months of treatment (ADAS-cog) among patients with mild-to-moderate AD. This superior effect persisted at 1 year (P = 0.055). This positive effect on the ADAS-cog performance after 6 months of treatment was more prominent among individuals entering the trial with higher MMSE scores (P = 0.054). Benefit on other clinical measures was identified in the atorvastatin-treated population compared with placebo. Accordingly, atorvastatin therapy may be of benefit in the treatment of mild-to-moderately affected AD patients, but the level of benefit produced may be predicated on earlier treatment. Evidence also suggests that atorvastatin may slow the progression of mild-to-moderate AD, thereby prolonging the quality of an afflicted individual's life.

Spatial and temporal variability of arsenic solid-state speciation in historically lead arsenate contaminated soils.

The arsenic (As) solid-state speciation (i.e., oxidation state, precipitates, and adsorption complexes) is one of the most important factors controlling dissolved As concentrations at As contaminated sites. In this case study, two representative subsurface samples (i.e., oxidized and semi-reduced sites) from former lead arsenate contaminated soils in the northeastern United States were chosen to investigate the effects of aging on As retention mechanisms using multiscale spectroscopic techniques. X-ray powder diffraction (XRD), synchrotron based microfocused (micro) XRD, in situ micro-synchrotron based X-ray fluorescence spectroscopy (SXRF), and micro-X-ray absorption near edge structure (XANES) spectroscopy were used to compliment the final bulk X-ray absorption spectroscopy (XAS) analyses. In the sample from an oxic area, As is predominantly (approximately 71%) present as As(V) adsorbed onto amorphous iron oxyhydroxides with a residue (approximately 29%) of an original contaminant, schultenite (PbHAsO4). Contrarily, there is no trace of schultenite in the sample from a semi-reduced area. Approximately 25% of the total As is present as adsorbed phases on amorphous iron oxyhydroxide and amorphous orpiment (As2S3). The rest of the fractions (approximately 46%) were identified as As(V)-Ca coprecipitates. This study shows that aging effects can significantly alter the original chemical constituent (schultenite) in soils, resulting in multi and site-specific As solid-state speciation. The variability in spatial and temporal scale may be important in assessing the environmental risk and in developing in situ remediation technologies.

Arsenate adsorption mechanisms at the allophane-water interface.

We investigated arsenate (As(V)) reactivity and surface speciation on amorphous aluminosilicate mineral (synthetic allophane) surfaces using batch adsorption experiments, powder X-ray diffraction (XRD), and X-ray absorption spectroscopy (XAS). The adsorption isotherm experiments indicated that As(V) uptake increased with increasing [As-(V)]0 from 50 to 1000 microM (i.e., Langmuir type adsorption isotherm) and that the total As adsorption slightly decreased with increasing NaCl concentrations from 0.01 to 0.1 M. Arsenate adsorption was initially (0-10 h) rapid followed by a slow continuum uptake, and the adsorption processes reached the steady state after 720 h. X-ray absorption spectroscopic analyses suggest that As(V) predominantly forms bidentate binuclear surface species on aluminum octahedral structures, and these species are stable up to 11 months. Solubility calculations and powder XRD analyses indicate no evidence of crystalline Al-As(V) precipitates in the experimental systems. Overall, macroscopic and spectroscopic evidence suggest that the As(V) adsorption mechanisms at the allophane-water interface are attributable to ligand exchange reactions between As-(V) and surface-coordinated water molecules and hydroxyl and silicate ions. The research findings imply that dissolved tetrahedral oxyanions (e.g., H2PO42- and H2AsO4(2-)) are readily retained on amorphous aluminosilicate minerals in aquifer and soils at near neutral pH. The inner-sphere adsorption mechanisms might be important in controlling dissolved arsenate and phosphate in amorphous aluminosilicate-rich low-temperature geochemical environments.

Effects of dissolved carbonate on arsenate adsorption and surface speciation at the hematite--water interface.

Effects of dissolved carbonate on arsenate [As(V)] reactivity and surface speciation at the hematite-water interface were studied as a function of pH and two different partial pressures of carbon dioxide gas [P(CO2) = 10(-3.5) atm and approximately 0; CO2-free argon (Ar)] using adsorption kinetics, pseudo-equilibrium adsorption/titration experiments, extended X-ray absorption fine structure spectroscopic (EXAFS) analyses, and surface complexation modeling. Different adsorbed carbonate concentrations, due to the two different atmospheric systems, resulted in an enhanced and/or suppressed extent of As(V) adsorption. As(V) adsorption kinetics [4 g L(-1), [As(V)]0 = 1.5 mM and I = 0.01 M NaCl] showed carbonate-enhanced As(V) uptake in the air-equilibrated systems at pH 4 and 6 and at pH 8 after 3 h of reaction. Suppressed As(V) adsorption was observed in the air-equilibrated system in the early stages of the reaction at pH 8. In the pseudo-equilibrium adsorption experiments [1 g L(-1), [As(V)]0 = 0.5 mM and I = 0.01 M NaCI], in which each pH value was held constant by a pH-stat apparatus, effects of dissolved carbonate on As(V) uptake were almost negligible at equilibrium, but titrant (0.1 M HCl) consumption was greater in the air-equilibrated systems (P(CO2) = 10(-3.5) atm) than in the CO2-free argon system at pH 4-7.75. The EXAFS analyses indicated that As(V) tetrahedral molecules were coordinated on iron octahedral via bidentate mononuclear ( 2.8 A) and bidentate binuclear (approximately equal to 3.3 A) bonding at pH 4.5-8 and loading levels of 0.46-3.10 microM m(-2). Using the results of the pseudo-equilibrium adsorption data and the XAS analyses, the pH-dependent As(V) adsorption under the P(CO2) = 10(-3.5) atm and the CO2-free argon system was modeled using surface complexation modeling, and the results are consistent with the formation of nonprotonated bidentate surface species at the hematite surfaces. The results also suggest that the acid titrant consumption was strongly affected by changes to electrical double-layer potentials caused by the adsorption of carbonate in the air-equilibrated system. Overall results suggest that the effects of dissolved carbonate on As(V) adsorption were influenced by the reaction conditions [e.g., available surface sites, initial As(V) concentrations, and reaction times]. Quantifying the effects of adsorbed carbonate may be important in predicting As(V) transport processes in groundwater, where iron oxide-coated aquifer materials are exposed to seasonally fluctuating partial pressures of CO2(g).

Arsenic speciation and reactivity in poultry litter.

Recent U.S. government action to lower the maximum concentration levels (MCL) of total arsenic (As) (10 ppb) in drinking water has raised serious concerns about the agricultural use of As-containing biosolids such as poultry litter (PL). In this study, solid-state chemical speciation, desorbability, and total levels of As in PL and long-term amended soils were investigated using novel synchrotron-based probing techniques (microfocused (micro) synchrotron X-ray fluorescence (SXRF) and micro-X-ray absorption near-edge structure (XANES) spectroscopies) coupled with chemical digestion and batch experiments. The total As levels in the PL were as high as approximately 50 mg kg(-1), and As(II/III and V) was always concentrated in abundant needle-shaped microscopic particles (approximately 20 microm x 850 microm) associated with Ca, Cu, and Fe and to a lesser extent with S, Cl, and Zn. Post-edge XANES features of litter particles are dissimilar to those of the organo-As(V) compound in poultry feed (i.e., roxarsone), suggesting possible degradation/transformation of roxarsone in the litter and/or in poultry digestive tracts. The extent of As desorption from the litter increased with increasing time and pH from 4.5 to 7, but at most 15% of the total As was released after 5 d at pH 7, indicating the presence of insoluble phases and/or strongly retained soluble compounds. No significant As accumulation (< 15 mg kg(-1)) was found in long-term PL-amended agricultural surface soils. This suggests that As in the PL may have undergone surface and subsurface transport processes. Our research results raise concerns about long-term PL amendment effects on As contamination in surrounding soil-water environments.

HMG-CoA reductase inhibitors (statins) in the treatment of Alzheimer's disease and why it would be ill-advise to use one that crosses the blood-brain barrier.

Increased circulating cholesterol has been long linked to an increased risk of coronary artery disease (CAD), and is now linked to an increased risk of developing Alzheimer s disease (AD). We first showed the neuropathologic link between CAD and AD as increased incidence of cerebral senile plaques in both disorders. We then showed that AD-like neuropathology occurred in the brains of cholesterol-fed rabbits; including increased -amyloid (Ab). Currently there are a number of transgenic mouse models of AD that exhibit enhanced Ab pathology if cholesterol diet is administered. Culture studies clearly show that excess cholesterol enhances beta-metabolism of amyloid precursor protein (APP) and production of -amyloidogenic peptides, and that sufficiently reducing cholesterol levels by inhibition of synthesis completely inhibits all beta-metabolism of APP. Our finding that the elevated levels of Ab in rabbits fed cholesterol diet could be cleared from the brain by resuming a control diet prompted the hypothesis that lowering cholesterol levels in the blood of AD patients may be of some clinical benefit. Pilot data suggests that therapeutically lowering circulating cholesterol may attenuate Ab production in the cholesterol-fed rabbit brain, may stabilize cognitive performance in mildly impaired AD patients, and may reduce the risk of developing AD. Accordingly, we have initiated a double-blind treatment trial evaluating Atorvastatin Na+ among 120 mild-to-moderately impaired AD subjects randomized to one of two groups receiving placebo or active drug once a day. Atorvastatin is one of a general class of HMG-CoA reductase inhibitor drugs called statins that lower cholesterol by inhibition of synthesis. We chose to use Atorvastatin in this AD Treatment Trial because it does not cross the blood-brain-barrier, and believe it would be ill-advised to use a statin that does. This position stems from the observations that excess cholesterol inhibits cholesterol synthesis and increases Ab production, that Ab kills cells in part by inhibiting cholesterol synthesis, and that statins acting at the neuronal level could further exacerbate degeneration in AD by further inhibition of necessary cholesterol synthesis.

Solid-state speciation of natural and alum-amended poultry litter using XANES spectroscopy.

While alum amendments have shown to be effective in lowering water-soluble phosphate levels in poultry litter, the mechanism by which this occurs is not fully known. To determine the solid-state speciation of phosphate in litter samples, experiments were conducted with X-ray absorption near edge structure (XANES) spectroscopy. XANES analysis reveals that, in unamended samples, phosphate is present as weakly bound inorganic as well as some organic phosphate, with some dicalcium phosphate-type calcium phosphates also present. When alum is applied in the houses, XANES results suggest that it precipitates out as amorphous Al(OH)3 and then reacts with phosphate via an adsorption mechanism. No evidence was found of aluminum phosphate precipitation in any samples.

Mechanisms of selenate adsorption on iron oxides and hydroxides.

Selenate (SeO4(2-)) is an oxyanion of environmental importance because of its toxicity to animals and its mobility in the soil environment. It is known that iron(III) oxides and hydroxides are important sorbents for SeO4(2-) in soils and sediments, but the mechanism of selenate adsorption on iron oxides has been the subject of intense debate. Our research employed Extended X-ray absorption fine structure and attenuated total reflectance-Fourier transform infrared spectroscopies to determine SeO4(2-) bonding mechanisms on hematite, goethite, and hydrous ferric oxide (HFO). It was learned that selenate forms only inner-sphere surface complexes on hematite but forms a mixture of outer- and inner-sphere surface complexes on goethite and HFO. This continuum of adsorption mechanisms is strongly affected by both pH and ionic strength. These results suggest that adsorption experiments should be conducted on several different iron oxides and over a wide range of reaction conditions to accurately assess the reactivity of oxyanions on iron oxides.

Zinc speciation in a smelter-contaminated soil profile using bulk and microspectroscopic techniques.

A soil profile contaminated as a result of Zn smelting operations from the historic Palmerton, PA smelting facility was characterized using X-ray absorption fine structure spectroscopy (XAFS) and X-ray diffraction (XRD) as bulk techniques, coupled with electron microprobe (EM), and microfocused XAFS as microscopic techniques to determine the chemical forms of Zn and elucidate its geochemical fate. The black, organic matter-rich topsoil contained 6200 mg/ kg Zn and was strongly acidic (pH 3.2). Bulk XAFS revealed that about 2/3 of Zn was bound in franklinite and 1/3 bound in sphalerite. Both minerals may have been aerially deposited from the smelter operation. Microspectroscopy detected also minor amounts of Zn adsorbed to Fe and Mn (hydr)oxides as inner-sphere sorption complexes, which may have formed after weathering of the Zn minerals. About 10% of the total Zn in this sample could be easily leached. In contrast, the yellowish, loamy subsoil contained less Zn (890 mg/kg) and had a higher pH of 3.9. XAFS revealed that Zn was mostly bound to Al-groups and to a lesser extent to Fe and Mn (hydr)oxides. Minor amounts of outer-sphere complexes or organic matter-bound Zn species could also be detected. About 70% of the total Zn content could be easily leached, indicating that outersphere sorption complexes have been underestimated and/ or inner-sphere sorption complexes are weak due to the low pH. The Zn forms in the subsoil most likely derive from weathering of the Zn minerals in the topsoil. Due to the lack of minerals incorporating Zn and due to the low pH, the availability of Zn in the subsoil is as high as in the topsoil, while the total concentration is almost 1 order of magnitude smaller.