Fusulinids are the most diverse, abundant and geographically widespread Paleozoic foraminifera which are widely considered to possess a "homogeneously microgranular" test microstructure composed of subangular grains of several micrometers in size. However, this texture appears to be a diagenetic artifact. Here we describe well-preserved Devonian calcareous fusulinids (Nanicella) from the Holy Cross Mountains (HCM) in central Poland. Foraminifera from Poland in which the primary nature of tests have not been masked by diagenesis are composed of low magnesium calcite spherical grains up to about 100 nanometers in diameter, identical to those observed in Recent and fossil hyaline foraminifera (Rotaliida, Globothalamea). These data call the paradigm of microgranular test microstructure of Foraminifera into question, and suggest a possible phylogenetic relationship between globothalamids and some fusulinids.
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http://dx.doi.org/10.1038/s41598-017-15666-1 | DOI Listing |
Alzheimers Dement
December 2024
Laboratory of Alzheimer's Neuroimaging and Epidemiology - LANE, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, Brescia, Italy.
Background: This study investigated microstructural features of the locus coeruleus to entorhinal cortex pathway (LC-EC) in relation to amyloid (A), tau (T), neurodegeneration (N) markers and cognitive impairment in memory clinic patients.
Method: 124 participants were recruited from the Geneva Memory Clinic (n=30 cognitively unimpaired - CU; n=80 MCI and n=14 dementia - CI) and underwent clinical assessment, 3T MRI scan including diffusion weighted imaging, amyloid PET, and tau PET. Diffusivity indices (fractional anisotropy - FA, mean, axial and radial diffusivities - MD, AxD, RD) were assessed in the LC-EC pathway using a probabilistic atlas.
Alzheimers Dement
December 2024
Glenn Biggs Institute for Alzheimer's & Neurodegenerative Diseases, San Antonio, TX, USA.
Background: Peak-width of skeletonized mean diffusivity (PSMD) is an emerging biomarker of cerebral small vessel disease (cSVD)-related vascular contributions to cognitive impairment and dementia (VCID). Higher PSMD values reflect greater white matter microstructural damage, and prior research has related PSMD to sporadic and monogenic forms of cSVD and worse cognitive function. Therefore, we proposed PSMD as a risk stratification biomarker for VCID.
View Article and Find Full Text PDFAlzheimers Dement
December 2024
Dementia Research Centre, UCL Queen Square Institute of Neurology, London, UK.
Background: Parkinson's (PD) is common and debilitating with over half of patients progressing to postural instability, dementia or death within 10 years. However, onset and rate of progression is highly variable, reflecting heterogeneity in underlying pathology, and biomarker studies to-date have been limited to a single modality or assessed patients with established cognitive impairment.
Method: We assessed multimodal neuroimaging and plasma biomarkers in 98 PD patients (mean disease duration at baseline 4.
Alzheimers Dement
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Wisconsin Alzheimer's Disease Research Center, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA.
Background: While magnetic resonance imaging (MRI) markers of neurodegeneration are nonspecific to Alzheimer's disease (AD) pathology, they have been correlated with cognitive dysfunction, and therefore, provide important information pertaining to disease staging. Neurodegeneration in AD is commonly assessed with macrostructural measures of brain atrophy, such as hippocampal volume. However, recent investigations have shown that markers of neural microstructure derived from diffusion MRI (DWI) may provide supplementary insight into the progression of AD pathophysiology.
View Article and Find Full Text PDFBackground: Recent advancements in molecular positron emission tomography (PET) enable precise tracking of tau pathology in Alzheimer's disease (AD). Tau pathology typically begins focally in the medial temporal lobe, rapidly expanding due to amyloid-β (Aβ) influence. This expansion may lead to neurodegeneration along connected pathways to the tau epicenters, resulting in cognitive decline.
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