Development of an analytical method for the analysis of diflubenzuron in whole blood, plasma, and serum using liquid chromatography tandem mass spectrometry.

The integration of free-range beef livestock into the human food chain has been continuously threatened by outbreaks of babesiosis, which is propagated by ticks that vector the protozoans that cause the disease. The protozoans are spread among livestock by certain species of ticks, known collectively as cattle fever ticks (CFT). Although eliminated from the US in the 1940s, CFT continue to infiltrate the US by crossing the US/Mexico border on stray livestock and wildlife, and infest cattle herds.

Overexpression of ameloblastin in secretory ameloblasts results in demarcated, hypomineralized opacities in enamel.

Developmental defects of the enamel manifest before tooth eruption and include amelogenesis imperfecta, a rare disease of underlying gene mutations, and molar-incisor hypomineralization (MIH), a prevalent disease in children originating from environmental and epigenetic factors. MIH enamel presents as the abnormal enamel marked by loss of translucency, demarcation between the healthy and affected enamel, and reduced mineral content. The pathophysiology of opaque, demarcated enamel lesions is not understood; however, the retention of enamel proteins in the matrix has been suggested.

Electron Doping of Semiconducting MoS Nanosheets by Silver or Gold Nanoclusters.

Semiconducting two-dimensional (2D) materials have potential applications as ultrathin optoelectronic materials. Therefore, being able to precisely modulate the band gap is useful to improving their applicability. Electron doping of the semiconducting materials is one of the successful techniques used to modulate their band gap.

Elevated dietary ω-6 polyunsaturated fatty acids induce reversible peripheral nerve dysfunction that exacerbates comorbid pain conditions.

Chronic pain is the leading cause of disability worldwide and is commonly associated with comorbid disorders. However, the role of diet in chronic pain is poorly understood. Of particular interest is the Western-style diet, enriched with ω-6 polyunsaturated fatty acids (PUFAs) that accumulate in membrane phospholipids and oxidise into pronociceptive oxylipins.

Ethanol-Fixed, Paraffin-Embedded Tissue Imaging: Implications for Alzheimer's Disease Research.

Mass spectrometry imaging (MSI) is rapidly becoming a crucial tool in disease research. Fresh-frozen tissue is ideal for MSI because the protein and lipid structures are undisturbed by chemical fixatives; however, that means long-term preservation is limited. Formalin-fixed paraffin-embedded tissue has a virtually infinite shelf life, but whole proteins are difficult or impossible to image directly.

Mapping and Identification of Native Proteins of Developing Teeth in Mouse Mandibles.

Mass spectrometry imaging is a powerful tool of increasing utility due to its ability to spatially resolve molecular biomarkers directly from sectioned tissues. One hindrance to its universality is that no single protocol is sufficient for every tissue type, fixation, and pretreatment. Mineralized tissues are uniquely challenging as extensive decalcification protocols are necessary to achieve thin sections.

Rapid method towards proteomic analysis of dried blood spots by MALDI mass spectrometry.

Neonatal dried blood spots (DBS) are routinely utilized in the clinical setting as a diagnostic tool for various genetic disorders and infectious diseases. DBS allow for minimally invasive, small volume blood collection and are stored at room temperature. Neonatal whole blood and serum samples can be important in determining genetic risk factors and predicting infantile disease; however, at the present time, limited methods exist for rapidly analyzing DBS samples for their proteomic profile, years after samples have been collected.

Analysis of post-translational modifications in Alzheimer's disease by mass spectrometry.

The roles of post-translational modifications (PTMs) in the onset and progression of disease have been extensively studied for decades. More specifically, various PTMs have been the focus of research in Alzheimer's disease (AD). The two most discussed hallmarks of the disease, senile plaques and tau tangles, are the result of PTMs of the amyloidβ protein precursor (AβPP) and the microtubule stabilizing protein: tau.

Characterization of Proteins Present in Isolated Senile Plaques from Alzheimer's Diseased Brains by MALDI-TOF MS with MS/MS.

The increase of insoluble senile plaques in the brain is a primary hallmark of Alzheimer's disease. The usefulness of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) with tandem MS for the characterization of senile plaques from AD brains and the relevance of the components identified to furthering AD research using MS is discussed. Thirty-three components were reproducibly observed within tryptic aliquots of senile plaques from two different AD brains after sample preparation optimization.

Liquid Chromatography Separation and Mass Spectrometry Detection of Silver-Lipoate Ag(LA) Nanoclusters: Evidence of Isomerism in the Solution Phase.

Evidence for the existence of condensed-phase isomers of silver-lipoate clusters, Ag(LA), where LA = (R)-α lipoic acid, was obtained by reversed-phase ion-pair liquid chromatography with in-line UV-vis and electrospray ionization (ESI)-MS detection. All components of a raw mixture were separated according to surface chemistry and increasing size via reversed-phase gradient HPLC methods and identified by their corresponding m/z ratio by ESI in the negative ionization mode. Aqueous and methanol mobile-phase mixtures, each containing 400 mM hexafluoroisopropanol (HFIP)-15 mM triethylamine (TEA), were employed to facilitate the interaction between the clusters and stationary phase via formation of ion-pairs.

Incubation with Cu(II) and Zn(II) salts enhances MALDI-TOF mass spectra of amyloid-beta and α-synuclein toward in vivo analysis.

Insoluble senile plaque aggregates are indicative of Alzheimer's disease pathology. A similar phenomenon occurs in Parkinson's disease with the build-up of Lewy bodies. The analysis of senile plaques, and other brain samples, from Alzheimer's disease and Parkinson's disease patients by matrix-assisted laser desorption/ionization mass spectrometry has advantages but also presents obstacles because of the nature of the processes utilized in isolation procedures and storage.

Molecular Mapping Alzheimer's Disease: MALDI Imaging of Formalin-fixed, Paraffin-embedded Human Hippocampal Tissue.

A method for the molecular mapping of formalin-fixed, paraffin-embedded human hippocampal tissue affected by Alzheimer's disease (AD) is presented. This approach utilizes imaging mass spectrometry (IMS) with matrix-assisted laser desorption/ionization (MALDI). The usefulness of this technique in comparing diseased nor mal tissue at the molecular level while continuing to maintain topological and morphological integrity is evident in the preliminary findings.

Selection and Identification of Molecular Gold Clusters at the Nano(gram) Scale: Reversed Phase HPLC-ESI-MS of a Mixture of Au-Peth MPCs.

Recent advances in cluster synthesis make it possible to produce an enormous variety molecule-like MPCs of size, composition, shape, and surface-chemical combinations. In contrast to the significant growth in the synthetic capability to generate these materials, progress in establishing the physicochemical basis for their observed properties has remained limited. The main reason for this has been the lack of the analytical capability to generate and measure samples of suitably high (molecular) purity; such capability is also essential to support therapeutic and diagnostic MPC development.

Capillary Liquid Chromatography Mass Spectrometry Analysis of Intact Monolayer-Protected Gold Clusters in Complex Mixtures.

In some respects, large noble-metal clusters protected by thiolate ligands behave as giant molecules of definite composition and structure; however, their rigorous analysis continues to be quite challenging. Analysis of complex mixtures of intact monolayer-protected clusters (MPCs) by liquid chromatography mass spectrometry (LC-MS) could provide quantitative identification of the various components present. This advance is critical for biomedical and toxicological research, as well as in fundamental studies that rely on the identification of selected compositions.

Laser-Induced In-Source Decay Applied to the Determination of Amyloid-Beta in Alzheimer's Brains.

A method for the analysis of amyloid-beta peptides in isolated plaques and intact tissue sections affected by Alzheimer's disease (AD) is presented. This method employs matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometry and the inherent laser-induced in-source decay (ISD) that occurs coupled with imaging mass spectrometry (IMS) to investigate the composition of these samples eliminating the need for other confirmational MS/MS techniques. These results demonstrate this technique's usefulness for the identification of amyloid-beta peptides in tissue and isolated senile plaques from AD patients using the reproducible fragmentation pattern demonstrated via the laser-induced ISD of synthetic amyloid-beta peptide clips (1-40, 1-42).

Collision-induced dissociation of monolayer protected clusters Au144 and Au130 in an electrospray time-of-flight mass spectrometer.

Gas-phase reactions of larger gold clusters are poorly known because generation of the intact parent species for mass spectrometric analysis remains quite challenging. Herein we report in-source collision-induced dissociation (CID) results for the monolayer protected clusters (MPCs) Au144(SR)60 and Au130(SR)50, where R- = PhCH2CH2-, in a Bruker micrOTOF time-of-flight mass spectrometer. A sample mixture of the two clusters was introduced into the mass spectrometer by positive mode electrospray ionization.

Structure & bonding of the gold-subhalide cluster I-Au144Cl60[z].

The structure and bonding of the gold-subhalide compounds Au144Cl60([z]) are related to those of the ubiquitous thiolated gold clusters, or Faradaurates, by iso-electronic substitution of thiolate by chloride. Exact I-symmetry holds for the [z] = [2+,4+] charge-states, in accordance with new electrospray mass spectrometry measurements and the predicted electron shell filling. The high symmetry facilitates analysis of the global structure as well as the bonding network, with some striking results.

Structure of the thiolated Au130 cluster.

The structure of the recently discovered Au130-thiolate and -dithiolate clusters is explored in a combined experiment-theory approach. Rapid electron diffraction in scanning/transmission electron microscopy (STEM) enables atomic-resolution imaging of the gold core and the comparison with density functional theory (DFT)-optimized realistic structure models. The results are consistent with a 105-atom truncated-decahedral core protected by 25 short staple motifs, incorporating disulfide bridges linking the dithiolate ligands.

STEM Electron Diffraction and High Resolution Images Used in the Determination of the Crystal Structure of Au(SR) Cluster.

Determination of the total structure of molecular nanocrystals is an outstanding experimental challenge that has been met, in only a few cases, by single-crystal X-ray diffraction. Described here is an alternative approach that is of most general applicability and does not require the fabrication of a single crystal. The method is based on rapid, time-resolved nanobeam electron diffraction (NBD) combined with high-angle annular dark field scanning/transmission electron microscopy (HAADF-STEM) images in a probe corrected STEM microscope, operated at reduced voltages.

Organocopper complexes during roxarsone degradation in wastewater lagoons.

Background, Aim, And Scope: Organoarsenical-containing animal feeds that promote growth and resistance to parasites are mostly excreted unchanged, ending up in nearby wastewater storage lagoons. Earlier work documented the partial transformation of organoarsenicals, such as, 3-nitro-4-hydroxyphenylarsonic acid (roxarsone) to the more toxic inorganic arsenate [As(V)] and 3-amino-4-hydroxyphenylarsonic acid (3-AHPAA). Unidentified roxarsone metabolites using liquid chromatography coupled to inductively coupled plasma mass spectrometry (LC/ICP-MS) were also inferred from the corresponding As mass balance.

Nitrous oxide supersaturation at the liquid/air interface of animal waste.

Concentrated animal feeding operations around the globe generate large amounts of nitrous oxide (N(2)O) in the surrounding atmosphere. Liquid animal waste systems have received little attention with respect to N(2)O emissions. We hypothesized that the solution chemistry of animal waste aqueous suspensions would promote conditions that lead to N(2)O supersaturation at the liquid/air interface.

Induction of lead-binding phytochelatins in vetiver grass [Vetiveria zizanioides (L.)].

Elevated lead (Pb) concentrations in residential houseyards around house walls painted with Pb-based pigments pose serious human health risks, especially to children. Vetiver grass (Vetiveria zizanioides L.) has shown promise for use in in situ Pb phytoremediation efforts.

An experimental and theoretical investigation into the hydrolysis of dichloro(ethylenediamine)platinum(II) via electrospray mass spectrometry and density functional theory.

Dichloro(ethylenediamine)platinum(II), Pt(en)Cl(2), was dissolved in H(2)O and D(2)O, and the resulting aqueous solutions were electrosprayed into a quadrupole ion-trap mass spectrometer. A series of major and minor ionic hydrolysis products were detected. These ions were then subjected to collision-induced dissociation.

Analysis of phytochelatin complexes in the lead tolerant vetiver grass [Vetiveria zizanioides (L.)] using liquid chromatography and mass spectrometry.

Ethylenediamene tetraacetic acid (EDTA) has been used to mobilize soil lead (Pb) and enhance plant uptake for phytoremediation. Chelant bound Pb is considered less toxic compared to free Pb ions and hence might induce less stress on plants. Characterization of possible Pb complexes with phytochelatins (PCn, metal-binding peptides) and EDTA in plant tissues will enhance our understanding of Pb tolerance mechanisms.

Do lagoons near concentrated animal feeding operations promote nitrous oxide supersaturation?

Animal wastewater lagoons nearby concentrated animal feeding operations (CAFOs) represent the latest tendency in global animal farming, severely impacting the magnitude of greenhouse gas emissions, including nitrous oxide (N(2)O). We hypothesized that lagoon wastewater could be supersaturated with N(2)O as part of incomplete microbial nitrification/denitrification processes, thereby regulating the N(2)O partitioning in the gaseous phase. The objectives of this study were: (i) to investigate the magnitude of dissolved N(2)O concentrations in the lagoon; and (ii) to determine the extent to which supersaturation of N(2)O occurs in wastewater lagoons.