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  1. Article ; Online: TDP-43 and tau concurrence in the entorhinal subfields in primary age-related tauopathy and preclinical Alzheimer's disease.

    Llamas-Rodríguez, Josué / Oltmer, Jan / Marshall, Michael / Champion, Samantha / Frosch, Matthew P / Augustinack, Jean C

    Brain pathology (Zurich, Switzerland)

    2023  Volume 33, Issue 4, Page(s) e13159

    Abstract: Phosphorylated tau (p-tau) pathology correlates strongly with cognitive decline and is a pathological hallmark of Alzheimer's Disease (AD). In recent years, phosphorylated transactive response DNA-binding protein (pTDP-43) has emerged as a common ... ...

    Abstract Phosphorylated tau (p-tau) pathology correlates strongly with cognitive decline and is a pathological hallmark of Alzheimer's Disease (AD). In recent years, phosphorylated transactive response DNA-binding protein (pTDP-43) has emerged as a common comorbidity, found in up to 70% of all AD cases (Josephs et al., Acta Neuropathol, 131(4), 571-585; Josephs, Whitwell, et al., Acta Neuropathol, 127(6), 811-824). Current staging schemes for pTDP-43 in AD and primary age-related tauopathy (PART) track its progression throughout the brain, but the distribution of pTDP-43 within the entorhinal cortex (EC) at the earliest stages has not been studied. Moreover, the exact nature of p-tau and pTDP-43 co-localization is debated. We investigated the selective vulnerability of the entorhinal subfields to phosphorylated pTDP-43 pathology in preclinical AD and PART postmortem tissue. Within the EC, posterior-lateral subfields showed the highest semi-quantitative pTDP-43 density scores, while the anterior-medial subfields had the lowest. On the rostrocaudal axis, pTDP-43 scores were higher posteriorly than anteriorly (p < 0.010), peaking at the posterior-most level (p < 0.050). Further, we showed the relationship between pTDP-43 and p-tau in these regions at pathology-positive but clinically silent stages. P-tau and pTDP-43 presented a similar pattern of affected subregions (p < 0.0001) but differed in density magnitude (p < 0.0001). P-tau burden was consistently higher than pTDP-43 at every anterior-posterior level and in most EC subfields. These findings highlight pTDP-43 burden heterogeneity within the EC and the posterior-lateral subfields as the most vulnerable regions within stage II of the current pTDP-43 staging schemes for AD and PART. The EC is a point of convergence for p-tau and pTDP-43 and identifying its most vulnerable neuronal populations will prove key for early diagnosis and disease intervention.
    MeSH term(s) Humans ; Alzheimer Disease/pathology ; Tauopathies/pathology ; tau Proteins/metabolism ; DNA-Binding Proteins/metabolism ; Entorhinal Cortex/metabolism ; Brain/pathology
    Chemical Substances tau Proteins ; DNA-Binding Proteins
    Language English
    Publishing date 2023-04-10
    Publishing country Switzerland
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 1051484-3
    ISSN 1750-3639 ; 1015-6305
    ISSN (online) 1750-3639
    ISSN 1015-6305
    DOI 10.1111/bpa.13159
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article: Pentad: A reproducible cytoarchitectonic protocol and its application to parcellation of the human hippocampus.

    Williams, Emily M / Rosenblum, Emma W / Pihlstrom, Nicole / Llamas-Rodríguez, Josué / Champion, Samantha / Frosch, Matthew P / Augustinack, Jean C

    Frontiers in neuroanatomy

    2023  Volume 17, Page(s) 1114757

    Abstract: Introduction: The hippocampus is integral for learning and memory and is targeted by multiple diseases. Neuroimaging approaches frequently use hippocampal subfield volumes as a standard measure of neurodegeneration, thus making them an essential ... ...

    Abstract Introduction: The hippocampus is integral for learning and memory and is targeted by multiple diseases. Neuroimaging approaches frequently use hippocampal subfield volumes as a standard measure of neurodegeneration, thus making them an essential biomarker to study. Collectively, histologic parcellation studies contain various disagreements, discrepancies, and omissions. The present study aimed to advance the hippocampal subfield segmentation field by establishing the first histology based parcellation protocol, applied to
    Methods: The protocol focuses on five cellular traits observed in the pyramidal layer of the human hippocampus. We coin this approach the pentad protocol. The traits were: chromophilia, neuron size, packing density, clustering, and collinearity. Subfields included were CA1, CA2, CA3, CA4, prosubiculum, subiculum, presubiculum, parasubiculum, as well as the medial (uncal) subfields Subu, CA1u, CA2u, CA3u, and CA4u. We also establish nine distinct anterior-posterior levels of the hippocampus in the coronal plane to document rostrocaudal differences.
    Results: Applying the pentad protocol, we parcellated 13 subfields at nine levels in 22 samples. We found that CA1 had the smallest neurons, CA2 showed high neuronal clustering, and CA3 displayed the most collinear neurons of the CA fields. The border between presubiculum and subiculum was staircase shaped, and parasubiculum had larger neurons than presubiculum. We also demonstrate cytoarchitectural evidence that CA4 and prosubiculum exist as individual subfields.
    Discussion: This protocol is comprehensive, regimented and supplies a high number of samples, hippocampal subfields, and anterior-posterior coronal levels. The pentad protocol utilizes the gold standard approach for the human hippocampus subfield parcellation.
    Language English
    Publishing date 2023-02-09
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2452969-2
    ISSN 1662-5129
    ISSN 1662-5129
    DOI 10.3389/fnana.2023.1114757
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Stereology neuron counts correlate with deep learning estimates in the human hippocampal subregions.

    Oltmer, Jan / Rosenblum, Emma W / Williams, Emily M / Roy, Jessica / Llamas-Rodriguez, Josué / Perosa, Valentina / Champion, Samantha N / Frosch, Matthew P / Augustinack, Jean C

    Scientific reports

    2023  Volume 13, Issue 1, Page(s) 5884

    Abstract: Hippocampal subregions differ in specialization and vulnerability to cell death. Neuron death and hippocampal atrophy have been a marker for the progression of Alzheimer's disease. Relatively few studies have examined neuronal loss in the human brain ... ...

    Abstract Hippocampal subregions differ in specialization and vulnerability to cell death. Neuron death and hippocampal atrophy have been a marker for the progression of Alzheimer's disease. Relatively few studies have examined neuronal loss in the human brain using stereology. We characterize an automated high-throughput deep learning pipeline to segment hippocampal pyramidal neurons, generate pyramidal neuron estimates within the human hippocampal subfields, and relate our results to stereology neuron counts. Based on seven cases and 168 partitions, we vet deep learning parameters to segment hippocampal pyramidal neurons from the background using the open-source CellPose algorithm, and show the automated removal of false-positive segmentations. There was no difference in Dice scores between neurons segmented by the deep learning pipeline and manual segmentations (Independent Samples t-Test: t(28) = 0.33, p = 0.742). Deep-learning neuron estimates strongly correlate with manual stereological counts per subregion (Spearman's correlation (n = 9): r(7) = 0.97, p < 0.001), and for each partition individually (Spearman's correlation (n = 168): r(166) = 0.90, p <0 .001). The high-throughput deep-learning pipeline provides validation to existing standards. This deep learning approach may benefit future studies in tracking baseline and resilient healthy aging to the earliest disease progression.
    MeSH term(s) Humans ; Deep Learning ; Image Processing, Computer-Assisted/methods ; Hippocampus ; Neurons ; Brain
    Language English
    Publishing date 2023-04-11
    Publishing country England
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 2615211-3
    ISSN 2045-2322 ; 2045-2322
    ISSN (online) 2045-2322
    ISSN 2045-2322
    DOI 10.1038/s41598-023-32903-y
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Assessing individual variability of the entorhinal subfields in health and disease.

    Oltmer, Jan / Greve, Douglas N / Cerri, Stefano / Slepneva, Natalya / Llamas-Rodríguez, Josue / Iglesias, Juan Eugenio / Van Leemput, Koen / Champion, Samantha N / Frosch, Matthew P / Augustinack, Jean C

    The Journal of comparative neurology

    2023  Volume 531, Issue 18, Page(s) 2062–2079

    Abstract: Investigating interindividual variability is a major field of interest in neuroscience. The entorhinal cortex (EC) is essential for memory and affected early in the progression of Alzheimer's disease (AD). We combined histology ground-truth data with ... ...

    Abstract Investigating interindividual variability is a major field of interest in neuroscience. The entorhinal cortex (EC) is essential for memory and affected early in the progression of Alzheimer's disease (AD). We combined histology ground-truth data with ultrahigh-resolution 7T ex vivo MRI to analyze EC interindividual variability in 3D. Further, we characterized (1) entorhinal shape as a whole, (2) entorhinal subfield range and midpoints, and (3) subfield architectural location and tau burden derived from 3D probability maps. Our results indicated that EC shape varied but was not related to demographic or disease factors at this preclinical stage. The medial intermediate subfield showed the highest degree of location variability in the probability maps. However, individual subfields did not display the same level of variability across dimensions and outcome measure, each providing a different perspective. For example, the olfactory subfield showed low variability in midpoint location in the superior-inferior dimension but high variability in anterior-posterior, and the subfield entorhinal intermediate showed a large variability in volumetric measures but a low variability in location derived from the 3D probability maps. These findings suggest that interindividual variability within the entorhinal subfields requires a 3D approach incorporating multiple outcome measures. This study provides 3D probability maps of the individual entorhinal subfields and respective tau pathology in the preclinical stage (Braak I and II) of AD. These probability maps illustrate the subfield average and may serve as a checkpoint for future modeling.
    MeSH term(s) Humans ; Hippocampus/pathology ; Magnetic Resonance Imaging/methods ; Entorhinal Cortex ; Alzheimer Disease/diagnostic imaging ; Alzheimer Disease/pathology
    Language English
    Publishing date 2023-09-12
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 3086-7
    ISSN 1096-9861 ; 0021-9967 ; 0092-7317
    ISSN (online) 1096-9861
    ISSN 0021-9967 ; 0092-7317
    DOI 10.1002/cne.25538
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: Entorhinal Subfield Vulnerability to Neurofibrillary Tangles in Aging and the Preclinical Stage of Alzheimer's Disease.

    Llamas-Rodríguez, Josué / Oltmer, Jan / Greve, Douglas N / Williams, Emily / Slepneva, Natalya / Wang, Ruopeng / Champion, Samantha / Lang-Orsini, Melanie / Fischl, Bruce / Frosch, Matthew P / van der Kouwe, André J W / Augustinack, Jean C

    Journal of Alzheimer's disease : JAD

    2022  Volume 87, Issue 3, Page(s) 1379–1399

    Abstract: Background: Neurofibrillary tangle (NFT) accumulation in the entorhinal cortex (EC) precedes the transformation from cognitive controls to mild cognitive impairment and Alzheimer's disease (AD). While tauopathy has been described in the EC before, the ... ...

    Abstract Background: Neurofibrillary tangle (NFT) accumulation in the entorhinal cortex (EC) precedes the transformation from cognitive controls to mild cognitive impairment and Alzheimer's disease (AD). While tauopathy has been described in the EC before, the order and degree to which the individual subfields within the EC are engulfed by NFTs in aging and the preclinical AD stage is unknown.
    Objective: We aimed to investigate substructures within the EC to map the populations of cortical neurons most vulnerable to tau pathology in aging and the preclinical AD stage.
    Methods: We characterized phosphorylated tau (CP13) in 10 cases at eight well-defined anterior-posterior levels and assessed NFT density within the eight entorhinal subfields (described by Insausti and colleagues) at the preclinical stages of AD. We validated with immunohistochemistry and labeled the NFT density ratings on ex vivo MRIs. We measured subfield cortical thickness and reconstructed the labels as three-dimensional isosurfaces, resulting in anatomically comprehensive, histopathologically validated tau "heat maps."
    Results: We found the lateral EC subfields ELc, ECL, and ECs (lateral portion) to have the highest tau density in semi-quantitative scores and quantitative measurements. We observed significant stepwise higher tau from anterior to posterior levels (p < 0.001). We report an age-dependent anatomically-specific vulnerability, with all cases showing posterior tau pathology, yet older individuals displaying an additional anterior tau burden. Finally, cortical thickness of each subfield negatively correlated with respective tau scores (p < 0.05).
    Conclusion: Our findings indicate that posterior-lateral subfields within the EC are the most vulnerable to early NFTs and atrophy in aging and preclinical AD.
    MeSH term(s) Aging ; Alzheimer Disease/diagnostic imaging ; Alzheimer Disease/pathology ; Entorhinal Cortex/pathology ; Humans ; Neurofibrillary Tangles/pathology ; Tauopathies/diagnostic imaging ; Tauopathies/pathology ; tau Proteins/metabolism
    Chemical Substances tau Proteins
    Language English
    Publishing date 2022-02-24
    Publishing country Netherlands
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 1440127-7
    ISSN 1875-8908 ; 1387-2877
    ISSN (online) 1875-8908
    ISSN 1387-2877
    DOI 10.3233/JAD-215567
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: Quantitative and histologically validated measures of the entorhinal subfields in

    Oltmer, Jan / Slepneva, Natalya / Llamas Rodriguez, Josue / Greve, Douglas N / Williams, Emily M / Wang, Ruopeng / Champion, Samantha N / Lang-Orsini, Melanie / Nestor, Kimberly / Fernandez-Ros, Nídia / Fischl, Bruce / Frosch, Matthew P / Magnain, Caroline / van der Kouwe, Andre J W / Augustinack, Jean C

    Brain communications

    2022  Volume 4, Issue 3, Page(s) fcac074

    Abstract: Neuroimaging studies have routinely used hippocampal volume as a measure of Alzheimer's disease severity, but hippocampal changes occur too late in the disease process for potential therapies to be effective. The entorhinal cortex is one of the first ... ...

    Abstract Neuroimaging studies have routinely used hippocampal volume as a measure of Alzheimer's disease severity, but hippocampal changes occur too late in the disease process for potential therapies to be effective. The entorhinal cortex is one of the first cortical areas affected by Alzheimer's disease; its neurons are especially vulnerable to neurofibrillary tangles. Entorhinal atrophy also relates to the conversion from non-clinical to clinical Alzheimer's disease. In neuroimaging, the human entorhinal cortex has so far mostly been considered in its entirety or divided into a medial and a lateral region. Cytoarchitectonic differences provide the opportunity for subfield parcellation. We investigated the entorhinal cortex on a subfield-specific level-at a critical time point of Alzheimer's disease progression. While MRI allows multidimensional quantitative measurements, only histology provides enough accuracy to determine subfield boundaries-the pre-requisite for quantitative measurements
    Language English
    Publishing date 2022-03-25
    Publishing country England
    Document type Journal Article
    ISSN 2632-1297
    ISSN (online) 2632-1297
    DOI 10.1093/braincomms/fcac074
    Database MEDical Literature Analysis and Retrieval System OnLINE

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