Determination of the urinary aglycone metabolites of vitamin K by HPLC with redox-mode electrochemical detection

We describe a method for the determination of the two major urinary metabolites of vitamin K as the methyl esters of their agyclone structures, 2-methyl-3-(3-3-carboxymethylpropyl)-1,4-naphthoquinone (5C-side-chain metabolite) and 2-methyl-3-(5-carboxy-3-methyl-2-pentenyl)-1,4-naphthoquinone (7C-side-chain metabolite), by HPLC with electrochemical detection (ECD) in the redox mode. Urinary salts were removed by reversed-phase (C18) solid phase extraction (SPE) and the predominately conjugated vitamin K metabolites hydrolysed with methanolic HCl. The resultant carboxylic acid aglycones were quantitatively methylated with diazomethane and fractionated by normal-phase (silica) SPE. Final analysis was by reversed-phase (C18) HPLC with a methanol-aqueous mobile phase. Metabolites were detected by amperometric, oxidative ECD of their quinol forms, which were generated by post-column coulometric reduction at an upstream electrode. The assay gave excellent linearity (r2 typically = 0.999) and high sensitivity with an on-column detection limit of <3.5 fmol (<1pg). The inter-assay precision was typically 10%. Metabolite recovery was compared to that of an internal standard (2-methyl-3-(7'-carboxy-heptyl)-1,4-naphthoquinone), added to urine samples just before analysis. Using this methodology we confirmed that the 5C- and 7C-metabolite were major catabolites of both phylloquinone (vitamin K1) and menaquinones (vitamin K2) in humans. We propose that the measurement of urinary vitamin K metabolite excretion is a candidate non-invasive marker of total vitamin K status

Host Selection of the giant willow aphid (Tuberolachnus salignus)

The giant willow aphid [Tuberolachnus salignus (Gmelin)] has recently become noteworthy as a potential pest species due to the increased uptake of willow, its host-plant, for use in growing biomass for energy production. In this paper we describe host selection studies of T. salignus on short rotation coppice (SRC) willow varieties in laboratory bioassays and field experiments. In laboratory olfactometry tests, T. salignus was significantly attracted to certain SRC willow varieties, but not to others. Field trials during 2007 and 2008 showed that T. salignus infestation levels varied significantly on different SRC willow varieties and that levels are highest on the varieties to which they are most strongly attracted in the laboratory bioassays

COMPILATION OF LABORATORY SCALE ALUMINUM WASH AND LEACH REPORT RESULTS

This report compiles and analyzes all known wash and caustic leach laboratory studies. As further data is produced, this report will be updated. Included are aluminum mineralogical analysis results as well as a summation of the wash and leach procedures and results. Of the 177 underground storage tanks at Hanford, information was only available for five individual double-shell tanks, forty-one individual single-shell tanks (e.g. thirty-nine 100 series and two 200 series tanks), and twelve grouped tank wastes. Seven of the individual single-shell tank studies provided data for the percent of aluminum removal as a function of time for various caustic concentrations and leaching temperatures. It was determined that in most cases increased leaching temperature, caustic concentration, and leaching time leads to increased dissolution of leachable aluminum solids

Observation of a topologically non-trivial surface state in half-Heusler PtLuSb (001) thin films.

The discovery of topological insulators, materials with bulk band gaps and protected cross-gap surface states in compounds such as Bi2Se3, has generated much interest in identifying topological surface states (TSSs) in other classes of materials. In particular, recent theoretical calculations suggest that TSSs may be found in half-Heusler ternary compounds. If experimentally realizable, this would provide a materials platform for entirely new heterostructure spintronic devices that make use of the structurally identical but electronically varied nature of Heusler compounds. Here we show the presence of a TSS in epitaxially grown thin films of the half-Heusler compound PtLuSb. Spin- and angle-resolved photoemission spectroscopy, complemented by theoretical calculations, reveals a surface state with linear dispersion and a helical tangential spin texture consistent with previous predictions. This experimental verification of topological behaviour is a significant step forward in establishing half-Heusler compounds as a viable material system for future spintronic devices

Atomic spectrometry updates. Review of advances in elemental speciation

This is the sixth Atomic Spectrometry Update (ASU) to focus specifically on advances in elemental speciation and covers a period of approximately 12 months from December 2012. This review deals with all aspects of the analytical speciation methods developed for: the determination of oxidation states; organometallic compounds; coordination compounds; metal and heteroatom- containing biomolecules, including metalloproteins, proteins, peptides and amino acids; and the use of metal-tagging to facilitate detection via atomic spectrometry. The review does not specifically deal with fractionation, sometimes termed operationally defined speciation. As with all ASU reviews 1-5 the coverage of the topic is confined to those methods that incorporate atomic spectrometry as the measurement technique. However, molecular MS techniques are covered where the use is in parallel or series with atomic spectrometry. As with previous years As and Se speciation continues to dominate current literature. However, research is moving further towards understanding the toxicological and beneficial mechanisms of these two elements. There is also in increase in macromolecular analysis, with a decrease in detection limits for some methodologies, which increases the potential clinical use of the techniques employed. The use of both atomic and molecular spectrometry is well developed in these fields, highlighting the interdisciplinary nature of today's research environment. The trend towards lower cost more rapid analytical methods, often involving non-chromatographic speciation, also continues apace. This journal is © 2014 the Partner Organisations

Atomic spectrometry update: Review of advances in elemental speciation

This is the 12th Atomic Spectrometry Update (ASU) to focus on advances in elemental speciation and covers a period of approximately 12 months from December 2018. This ASU review deals with all aspects of the analytical atomic spectrometry speciation methods developed for: the determination of oxidation states; organometallic compounds; coordination compounds; metal and heteroatom-containing biomolecules, including metalloproteins, proteins, peptides and amino acids; and the use of metal-tagging to facilitate detection via atomic spectrometry. As with all ASU reviews the focus of the research reviewed includes those methods that incorporate atomic spectrometry as the measurement technique. However, because speciation analysis is inherently focused on the relationship between the metal(loid) atom and the organic moiety it is bound to, or incorporated within, atomic spectrometry alone cannot be the sole analytical approach of interest. For this reason molecular detection techniques are also included where they have provided a complementary approach to speciation analysis. This year the number of publications concerning As speciation has fallen by about half, as have studies on Se speciation. Growth areas continue to be Hg and ‘biomolecules’, with the number of reports concerning halogen and sulfur speciation also rising. The number of elements covered this year is again over 20, showing the breadth of the elemental speciation field

Studying Cat (Felis catus) Diabetes: Beware of the Acromegalic Imposter

Naturally occurring diabetes mellitus (DM) is common in domestic cats (Felis catus). It has been proposed as a model for human Type 2 DM given many shared features. Small case studies demonstrate feline DM also occurs as a result of insulin resistance due to a somatotrophinoma. The current study estimates the prevalence of hypersomatotropism or acromegaly in the largest cohort of diabetic cats to date, evaluates clinical presentation and ease of recognition. Diabetic cats were screened for hypersomatotropism using serum total insulin-like growth factor-1 (IGF-1; radioimmunoassay), followed by further evaluation of a subset of cases with suggestive IGF-1 (>1000 ng/ml) through pituitary imaging and/ or histopathology. Clinicians indicated pre-test suspicion for hypersomatotropism. In total 1221 diabetic cats were screened; 319 (26.1%) demonstrated a serum IGF-1>1000 ng/ml (95% confidence interval: 23.6-28.6%). Of these cats a subset of 63 (20%) underwent pituitary imaging and 56/63 (89%) had a pituitary tumour on computed tomography; an additional three on magnetic resonance imaging and one on necropsy. These data suggest a positive predictive value of serum IGF-1 for hypersomatotropism of 95% (95% confidence interval: 90-100%), thus suggesting the overall hypersomatotropism prevalence among UK diabetic cats to be 24.8% (95% confidence interval: 21.2-28.6%). Only 24% of clinicians indicated a strong pre-test suspicion; most hypersomatotropism cats did not display typical phenotypical acromegaly signs. The current data suggest hypersomatotropism screening should be considered when studying diabetic cats and opportunities exist for comparative acromegaly research, especially in light of the many detected communalities with the human disease

Skeletal trade-offs in coralline algae in response to ocean acidification

Ocean acidification is changing the marine environment, with potentially serious consequences for many organisms. Much of our understanding of ocean acidification effects comes from laboratory experiments, which demonstrate physiological responses over relatively short timescales. Observational studies and, more recently, experimental studies in natural systems suggest that ocean acidification will alter the structure of seaweed communities. Here, we provide a mechanistic understanding of altered competitive dynamics among a group of seaweeds, the crustose coralline algae (CCA). We compare CCA from historical experiments (1981-1997) with specimens from recent, identical experiments (2012) to describe morphological changes over this time period, which coincides with acidification of seawater in the Northeastern Pacific. Traditionally thick species decreased in thickness by a factor of 2.0-2.3, but did not experience a change in internal skeletal metrics. In contrast, traditionally thin species remained approximately the same thickness but reduced their total carbonate tissue by making thinner inter-filament cell walls. These changes represent alternative mechanisms for the reduction of calcium carbonate production in CCA and suggest energetic trade-offs related to the cost of building and maintaining a calcium carbonate skeleton as pH declines. Our classification of stress response by morphological type may be generalizable to CCA at other sites, as well as to other calcifying organisms with species-specific differences in morphological types

Limited hybridization between introduced and Critically Endangered indigenous tilapia fishes in northern Tanzania

Hybridization between introduced and indigenous species can lead to loss of unique genetic resources and precipitate extinction. In Tanzania, the Nile tilapia (Oreochromis niloticus) and blue-spotted tilapia (Oreochromis leucostictus) have been widely introduced to non-native habitats for aquaculture and development of capture fisheries. Here, we aimed to quantify interspecific hybridization between these introduced species and the indigenous species Oreochromis esculentus, Oreochromis jipe and Oreochromis korogwe. In the Pangani basin, several hybrids were observed (O. niloticus × O. jipe, O. leucostictus × O. jipe, O. niloticus × O. korogwe), although hybrids were relatively uncommon within samples relative to purebreds. Hybrids between the native O. jipe × O. korogwe were also observed. In the Lake Victoria basin, no evidence of hybrids was found. Analysis of body shape using geometric morphometrics suggested that although purebreds could be discriminated from one another, hybrids could not be readily identified on body and head shape alone. These results provide the first evidence of hybridization between the introduced species and the Critically Endangered O. jipe in Tanzania. Given uncertainty regarding benefits of introduced species over large-bodied indigenous species in aquaculture and capture fisheries, we suggest that future introductions of hybridization-prone species should be carefully evaluated