Analysis of fluorine via 19F(n,)20F decay in the presence of a Na interferant using NAA [abstract]

Abstract only availableSociety's concern with the development of innovative diagnostic tools in medicine has prompted a great deal of interest in research. An important area of research includes the development of molecular imaging agents. These agents hold promise for noninvasive in vivo imaging, quantification, and monitoring of important biomarkers for several diseases including atherosclerosis and cancer. This area of research has benefited greatly from instrumental neutron activation analysis. INAA is an analytical technique that is useful for performing quantitative multi-elemental analysis. NAA is superior to other forms of analysis of its ability to simultaneously analyze several elements in a sample and it offers high sensitivity; part per million to low part per billion level. The imaging agent of interest in this project is a lipid encapsulated, liquid perfluorocarbon nanoparticle directly coupled to a selective v3-integrin ligand. The nanoparticle also contains the paramagnetic contrast agent gadolinium linked to the nanoparticle as Gd-DTPA-bis-oleate.1 Utilizing INAA, analysis of this molecular imaging agent for its concentration in biological tissue, specifically, rabbit aortas via a 19F(n, )20F reaction. Measurement of fluorine in tissue is particularly difficult due to fluorine's short half-life (t1/2 = 11s) and sodium's interference via a fast neutron reaction. INAA will also be employed to quantitatively determine the concentration of gadolinium in biological tissues. These measurements will allow for the comparison of Gd to F ratio pre-injection to the Gd to F ratio post-injection. Efficiency of Gd's arrival at the target location will be determined by the comparison of these ratios. (Image included in PDF

Data mining as a tool for environmental scientists

Over recent years a huge library of data mining algorithms has been developed to tackle a variety of problems in fields such as medical imaging and network traffic analysis. Many of these techniques are far more flexible than more classical modelling approaches and could be usefully applied to data-rich environmental problems. Certain techniques such as Artificial Neural Networks, Clustering, Case-Based Reasoning and more recently Bayesian Decision Networks have found application in environmental modelling while other methods, for example classification and association rule extraction, have not yet been taken up on any wide scale. We propose that these and other data mining techniques could be usefully applied to difficult problems in the field. This paper introduces several data mining concepts and briefly discusses their application to environmental modelling, where data may be sparse, incomplete, or heterogenous

Effects of washings and treatments on the usefulness of hair as a biomarker

Abstract only availableHair is a useful matrix for the analysis of many trace elements found in the human body. Studies show that hair can incorporate trace metals into its structure during the growth process. Hair is an attractive monitor because unlike blood serum and urine, it is a metabolic end product and therefore inert. It is collected non-invasively, easily stored and disposed. Many studies in the literature attempt to correlate trace elements measured in hair to health, pollution exposure or to disease. Trace elements in hair can be accurately measured by Instrumental Neutron Activation Analysis (INAA). Hair samples must be cleaned before analysis to remove external contamination, there are many methods of sample cleaning, however there is not a standardized washing procedure. This study investigates pre and post collection cleaning techniques that may alter observed trace element concentrations in the hair. Two separate, post collection washing methods were studied: the International Atomic Energy Agency, IAEA, method, and the University of Missouri Research Reactor, MURR, method. The samples were then analyzed for Se, Ti, Mg, Mn, V, I and Zn using INAA at MURR. Selenium concentrations were unchanged. However, all other elements showed a significant reduction in concentration from the MURR to the IAEA method. It was also hypothesized that pre-collection cleaning with shampoos containing EDTA, a chelating agent, may be responsible for leaching some trace metals from hair. In order to determine the effects of shampoos on the sample, hair from a single subject was treated with three different types of shampoo. Two solutions of each shampoo were prepared in a 1:4, shampoo:water ratio. The hair was then washed in these solutions for either 1 or 24 hours for each type of shampoo. Hair washed with shampoo containing selenium sulfide resulted in a large selenium contamination despite cleaning with both the IAEA and MURR methods. The large variability between the post-collection cleaning techniques shows that a standard preparation method must be established before hair can be accurately used as a biomarker. Further studies must be done to determine if pre-collection shampoo treatment affects the validity of hair as a biomarker for trace elements.NSF-REU/NIH Program in Radiochemistr

Phosphatidylinositol-(4,5)-bisphosphate regulates sorting signal recognition by the clathrin-associated adaptor complex AP2

The alpha,beta2,mu2,sigma2 heterotetrameric AP2 complex is recruited exclusively to the phosphatidylinositol-4,5-bisphosphate (PtdIns4,5P(2))-rich plasma membrane where, amongst other roles, it selects motif-containing cargo proteins for incorporation into clathrin-coated vesicles. Unphosphorylated and mu2Thr156-monophosphorylated AP2 mutated in their alphaPtdIns4,5P(2), mu2PtdIns4,5P(2), and mu2Yxxvarphi binding sites were produced, and their interactions with membranes of different phospholipid and cargo composition were measured by surface plasmon resonance. We demonstrate that recognition of Yxxvarphi and acidic dileucine motifs is dependent on corecognition with PtdIns4,5P(2), explaining the selective recruitment of AP2 to the plasma membrane. The interaction of AP2 with PtdIns4,5P(2)/Yxxvarphi-containing membranes is two step: initial recruitment via the alphaPtdIns4,5P(2) site and then stabilization through the binding of mu2Yxxvarphi and mu2PtdIns4,5P(2) sites to their ligands. The second step is facilitated by a conformational change favored by mu2Thr156 phosphorylation. The binding of AP2 to acidic-dileucine motifs occurs at a different site from Yxxvarphi binding and is not enhanced by mu2Thr156 phosphorylation

The Effect of High Intensity Exercise Training Verses Low Intensity Exercise Training on Fractionated Plasma High-Density Lipoprotein Cholesterol

Exercise training is thought to result in an elevation of high-density lipoprotein (HDL) and the cardioprotective subfraction HDL{dollar}\sb2{dollar}. Twenty-five healthy women (39 {dollar}\pm{dollar} 7.8 yrs; 70 {dollar}\pm{dollar} 14 kg) walked two miles three times per week for 12 weeks to examine the effect of exercise intensity on the HDL profile. The L.I. group (N = 12) walked at 60% of the heart rate reserve (HRR) and the H.I. group (N = 13) walked at 80% HRR both maintaining the prescribed distance and frequency. A 22% increase in total HDL (from 32 {dollar}\pm{dollar} 6 to 39 {dollar}\pm{dollar} 8 mg/dl) and a 35% increase in HDL{dollar}\sb2{dollar} (from 14 {dollar}\pm{dollar} 3 to 19 {dollar}\pm{dollar} 9 mg/dl) was elicited as a result of the walking program (p {dollar}\u3c{dollar}.005). Slight increases in HDL{dollar}\sb3{dollar} were also observed. However, no significant differences in total HDL or HDL{dollar}\sb2{dollar} were observed between the L.I. and H.I. groups. These findings demonstrate an exercise induced enhancement of the cardioprotective mechanism thought to be associated with the HDL{dollar}\sb2{dollar} subfraction. Moreover, it appears that walking at 80% of the HRR offers no advantage over walking at 60% of the HRR in enhancing the HDL profile

Neutron activation analysis of mercury in petroleum distillates

Abstract only availableIn liquefied natural gas (LNG) plants and nitrogen rejections units (NRU) that utilize aluminum heat exchangers, mercury (Hg) contaminates can result in corrosion of equipment, poisoning of catalysts, mechanical failure, and gas leakage. The purity of the product streams from these plants is also important due to the fact that many of the resulting products such as naphtha are used as feedstock for ethylene production and various solvents. Analytical methods such as chemical extractions (CE), combustion/trap (CT), atomic fluorescent spectrometry (AFS), and inductively coupled plasma optical emission spectrometry (ICP-OES) have been used to measure mercury in petroleum distillates. These methods require extensive sample preparation. A mercury analytical method that can be applied to distillates in routine operation that minimizes mercury loss from sampling preparation is needed. Neutron Activation Analysis (NAA) is a sensitive analytical technique that can be applied to samples as received. The objective of this work was to develop a NAA procedure for testing Hg in naphtha. Virgin naphtha samples were spiked with Hg at concentrations of 20, 50, 200, 500, 1000 and 1500 ng/g. One set of samples were prepared 3 days prior to irradiation and the second set was prepared and irradiated the same day. Analysis of the samples proved that even at small samples sizes (~800 µl) concentrations of 50 to 1500 ng/g of mercury in naphtha are easily detected and give a linear response. Samples that were prepared and irradiated on the same day showed less Hg loss than those prepared 3 days prior to irradiation. Analysis of multiple (n=5) 200 ng/g samples yielded a precision of 9% RSD. The minimum detectable amount of Hg using this technique is 5 ng.NSF-REU Radiochemistr

Mountain and meadow: A reconstruction of long-term pastoralist ecology in the Kashmir Valley

The cultural history of the Kashmir Valley in the Western Himalayas spans at least 4500 years, beginning with some of the known Neolithic Agricultural villages in the mountainous regions of the northern Indian Subcontinent. The development of agriculture in the valley, and subsequent periods of cultural expansion have been attributed to economic growth that capitalised on warm-humid climate phases in the region, often followed by periods of supposed social collapse driven by the onset of cold-arid conditions. More recently, Kashmiri archaeologists have argued that these near-Malthusian interpretations result from a methodological focus on a handful of large sites, and that the Kashmir Valley contains multiple ecological niches suitable for a wide range of economic or ecological adaptation. This study seeks to build on palaeoenvironmental and archaeological data that suggests a more complex picture of social and ecological change in the valley. Rather than using archaeological remains, this study draws on environmental signatures of pastoralist usage, enrichment or modification of environmental niches at middle and high altitudes, primarily on the western flank of the Kashmir Valley. These data include changes in pollen spectra, charcoal and fungal spore accumulation or sediment deposition that are indicative of pastoralist activity in mountain regions, and are interpreted through the lens of niche construction theory. The results indicate that pastoralist land usage in the upland areas of Kashmir was spatially and temporally discontinuous, and likely entangled with other environmental and historical processes. Stronger signatures for pastoralism often appear contemporary with drier conditions and periods of regional agricultural intensification, indicating that upland summer season herding may be an adaptive strategy to mitigate other ecological or economic pressures

Reviewing the Palaeoenvironmental Record to Better Understand Long-Term Human-Environment Interaction in Inner Asia During the Late Holocene

The Middle to Late Holocene spread of agropastoralism throughout Eurasia not only subjected domesticated taxa to stressors associated with novel environments but also induced changes in these environments following the introduction of these social-ecological systems. The mountainous region of Inner Asia comprises various steppe, meadow, and forest landscapes where zooarchaeological evidence suggests occupation by herding populations as early as 7,000 years Before Present (BP). Recent archaeobotanical findings indicate the introduction of cropping and the development of agropastoralism around 4,500 BP. Here, we review and synthesize palaeoenvironmental studies and data to examine anthropogenic impacts and modifications of these landscapes. From around 4,000 BP, we find significant changes in palynomorph, charcoal, sediment, and other proxy data, related to the introduction of agriculture to the region, with later intensifications in land use indicators at around 2,000 and 1,000 BP. We note that these impacts are not uniform or continuous through and across the records and may be evidence of shifting phases of occupation and landscape management. This temporal and spatial variability may also be a response to shifts in moisture availability due to long-term Holocene changes in the intensity of the summer monsoon and Westerly circulation systems. Changes in arboreal pollen indicate the development of intensified use of forest resources in the region, which we identify as a topic for future investigation. Based on these data, we stress the long-term human paleoecology in the study area and argue that traditional agropastoralist systems should be considered in future programs of landscape conservation in the region. This study also emphasizes the importance of future local scale multiproxy studies into past anthropogenic changes within the Inner Asian landscape

Nutritional Skewing of Conceptus Sex in Sheep: Effects of a Maternal Diet Enriched in Rumen-Protected Polyunsaturated Fatty acids (PUFA)

doi:10.1186/1477-7827-6-21Evolutionary theory suggests that in polygynous mammalian species females in better body condition should produce more sons than daughters. Few controlled studies have however tested this hypothesis and controversy exists as to whether body condition score or maternal diet is in fact the determining factor of offspring sex. Here, we examined whether maternal diet, specifically increased n-6 polyunsaturated fatty acid(PUFA) intake, of ewes with a constant body condition score around the time of conception influenced sex ratio.The research was supported by USDA/CSREES/NRI Grant 2001-35203- 10693 (to RMR) and a Life Sciences Molecular Biology Fellowship, University of Missouri (partial salary support for MPG)