Combined use of magnetometry and spectroscopy for identifying magnetofossils in sediments

Identification of the mineral remains of magnetotactic bacteria (MTB),known as magnetofossils, is of particular interest because theiroccurrence can be used for environmental and climatic reconstructions.Single-domain magnetite particles, which are biomineralized in the cellbody of MTB, have characteristic properties that can be used to detecttheir fossil remains. Acquisition of anhysteretic and isothermalremanent magnetization (ARM and IRM), first-order reversal curve (FORC)diagrams, and ferromagnetic resonance (FMR) spectra were used to detectthe magnetic mineral inventory in Holocene lake sediments. A comparativeanalysis in terms of the discriminatory power of these methods ispresented. The FORC diagrams contain two distinct features: a sharphorizontal ridge centered on the horizontal axis B-c and a feature withsymmetric spread along the vertical B-b axis. The coercivity spectraderived from the central ridge coincides with that derived from ARM andIRM acquisition curves and is compatible with the presence ofnoninteracting linear chains of single-domain magnetite. The secondfeature on FORC diagrams is indicative of interacting particles inclusters. In the FMR spectra from bulk sediment, two populations areseparated empirically based on the FORC information. An asymmetricsignal is taken to describe the population, which contains single-domainparticles in clusters. Empirical spectral separation of thiscontribution results in FMR spectra that are similar to those of intactMTB, which strongly suggests that a fraction of linear magnetosomechains is present. Combination of FMR and FORC results demonstrates thestrong potential of these methods for identifying magnetofossils, basedon alignment and interaction patterns of magnetic particles

Quantitative 18F-AV1451 Brain Tau PET Imaging in Cognitively Normal Older Adults, Mild Cognitive Impairment, and Alzheimer's Disease Patients

Recent developments of tau Positron Emission Tomography (PET) allows assessment of regional neurofibrillary tangles (NFTs) deposition in human brain. Among the tau PET molecular probes, 18F-AV1451 is characterized by high selectivity for pathologic tau aggregates over amyloid plaques, limited non-specific binding in white and gray matter, and confined off-target binding. The objectives of the study are (1) to quantitatively characterize regional brain tau deposition measured by 18F-AV1451 PET in cognitively normal older adults (CN), mild cognitive impairment (MCI), and AD participants; (2) to evaluate the correlations between cerebrospinal fluid (CSF) biomarkers or Mini-Mental State Examination (MMSE) and 18F-AV1451 PET standardized uptake value ratio (SUVR); and (3) to evaluate the partial volume effects on 18F-AV1451 brain uptake.Methods: The study included total 115 participants (CN = 49, MCI = 58, and AD = 8) from the Alzheimer's Disease Neuroimaging Initiative (ADNI). Preprocessed 18F-AV1451 PET images, structural MRIs, and demographic and clinical assessments were downloaded from the ADNI database. A reblurred Van Cittertiteration method was used for voxelwise partial volume correction (PVC) on PET images. Structural MRIs were used for PET spatial normalization and region of interest (ROI) definition in standard space. The parametric images of 18F-AV1451 SUVR relative to cerebellum were calculated. The ROI SUVR measurements from PVC and non-PVC SUVR images were compared. The correlation between ROI 18F-AV1451 SUVR and the measurements of MMSE, CSF total tau (t-tau), and phosphorylated tau (p-tau) were also assessed.Results:18F-AV1451 prominently specific binding was found in the amygdala, entorhinal cortex, parahippocampus, fusiform, posterior cingulate, temporal, parietal, and frontal brain regions. Most regional SUVRs showed significantly higher uptake of 18F-AV1451 in AD than MCI and CN participants. SUVRs of small regions like amygdala, entorhinal cortex and parahippocampus were statistically improved by PVC in all groups (p < 0.01). Although there was an increasing tendency of 18F-AV-1451 SUVRs in MCI group compared with CN group, no significant difference of 18F-AV1451 deposition was found between CN and MCI brains with or without PVC (p > 0.05). Declined MMSE score was observed with increasing 18F-AV1451 binding in amygdala, entorhinal cortex, parahippocampus, and fusiform. CSF p-tau was positively correlated with 18F-AV1451 deposition. PVC improved the results of 18F-AV-1451 tau deposition and correlation studies in small brain regions.Conclusion: The typical deposition of 18F-AV1451 tau PET imaging in AD brain was found in amygdala, entorhinal cortex, fusiform and parahippocampus, and these regions were strongly associated with cognitive impairment and CSF biomarkers. Although more deposition was observed in MCI group, the 18F-AV-1451 PET imaging could not differentiate the MCI patients from CN population. More tau deposition related to decreased MMSE score and increased level of CSF p-tau, especially in ROIs of amygdala, entorhinal cortex and parahippocampus. PVC did improve the results of tau deposition and correlation studies in small brain regions and suggest to be routinely used in 18F-AV1451 tau PET quantification

High-Throughput Analysis of In-Vitro Cytochrome P450 Inhibition Samples Using Mass Spectrometry Coupled with an Integrated Liquid Chromatography and Autosampler System

No Abstrac

Chaetomorpha philippinensis

A new marine microfilamentous green alga, Chaetomorpha philippinensis Leliaert sp. nov., is described as an epiphyte on Chaetomorpha vieillardii from shallow subtidal habitats in the Philippines. Phylogenetic analyses of large subunit rDNA and rDNA internal transcribed spacer (ITS) sequences show that the new tropical species is sister to the cold-water Chaetomorpha norvegica, from which it is genetically clearly distinct but morphologically almost indistinguishable. Chaetomorpha philippinensis is characterized by minute, straight or curved, unbranched, erect filaments up to 300 mu m long and 7-17 mu m in diameter, attached by a basal, hapteroid holdfast. Filaments in culture are similar in morphology but grow considerably longer with slightly larger cells. The cylindrical cells are multinucleate with up to eight nuclei (up to 18 in culture). Cells contain a single, parietal, lobed chloroplast with numerous small perforations and one to several pyrenoids. Zoosporangia develop by transformation of apical and subapical cells with zoids emerging through a domed pore in the apical, middle or basal part of the cell