Brain Specimens Research Articles

Peripheral blood regulatory B and T cells are decreased in patients with focal epilepsy

Patients with focal epilepsy of unknown cause (FEoUC) may display T cell infiltration in post-surgery brain specimens and increased serum levels of pro-inflammatory cytokines produced by B and T cells, indicating potential involvement of adaptive immunity. Our study aimed to investigate the peripheral blood distribution of B and T cell subgroups to find clues supporting the distinct organization of adaptive immunity in FEoUC. Twenty-two patients with FEoUC and 25 age and sex matched healthy individuals were included. Peripheral blood mononuclear cells were immunophenotyped by flow cytometry. Expression levels of anti-inflammatory cytokines and FOXP3 were measured by real-time PCR. Carboxyfluorescein succinimidyl ester (CFSE) proliferation assay was conducted using CD4+ T cells. Patients with FEoUC showed significantly decreased regulatory B (Breg), B1a, plasmablast and regulatory T (Treg) cell percentages, and increased switched memory B and Th17 cell ratios. Moreover, CD4+CD25+CD49d− Tregs of FEoUC patients displayed significantly reduced TGFB1 and FOXP3, but increased IL10 gene expression levels. CD4+ helper T cells of patients with FEoUC gave more exaggerated proliferation responses to phytohemagglutinin, anti-CD3 and anti-CD28 stimulation. Patients with FEoUC display increased effector lymphocyte, decreased regulatory lymphocyte ratios, and impaired Treg function and enhanced lymphocyte proliferation capacity. Overall, this pro-inflammatory phenotype lends support to the involvement of adaptive immunity in FEoUC.

Evaluation the Effect of Sonodynamic Therapy with 5-Aminolevulinic Acid and Sodium Fluorescein by Preclinical Animal Study.

Sonodynamic therapy (SDT) is a novel tumor treatment that combines biosafe sonosensitizers and noninvasive focused ultrasound to eradicate solid tumors. Sonosensitizers such as 5-aminolevulinic acid and fluorescein have great potential in tumor treatment. Here, rodent subcutaneous and brain tumor models were used to evaluate the treatment effect of both 5-ALA- and fluorescein-mediated SDT. The subcutaneous tumor growth rates of both SDT groups were significantly inhibited compared with that of the control groups. For intracranial tumors, 5-ALA-SDT treatment significantly inhibited brain tumor growth, while fluorescein-SDT exerted no therapeutic effect in animals. The distribution of fluorescein in the brain tumor region underwent further assessment. Seven days post tumor implantation, experimental animals received fluorescein and were sacrificed for brain specimen collection. Analysis of the dissected brains revealed no fluorescence signals, indicating an absence of fluorescein accumulation in the early-stage glioma tissue. These data suggest that the fluorescein-SDT treatment response is closely related to the amount of accumulated fluorescein. This study reports the equivalent effects of 5-ALA and fluorescein on the treatment of somatic tumors. For orthotopic brain tumor models, tumor vascular permeability should be considered when choosing fluorescein as a sonosensitizer. In conclusion, both fluorescein and 5-ALA are safe and effective SDT sonosensitizers, and the tumor microenvironment and pathologic type should be considered in the selection of adequate sonosensitizers.

Zinc-based fixative as a novel approach for histological preservation: A comparative study with formalin-based fixatives.

Formalin is a widely used histological fixative despite its carcinogenic properties, inadequate nucleic acid preservation, and prolonged fixation time. The study intended to prepare a novel zinc-based fixative that is, formalin-free, and cost-effective, provides optimal preservation, with rapid penetration rates, and enhanced Hematoxylin/Eosin-stained sections. Liver, kidney, brain, and small intestine specimens were collected from 10 adult laboratory rats (Rattus norvegicus) and preserved in formalin 4%, formalin 10%, neutral buffered formalin (NBF), and the experimental EZAT solution. The penetration depth (discolored edges) was measured at 6, 12, 24, and 48 hours. The shrinkage ratio was calculated by measuring the width and length of the samples before and after 48 hours of fixation. The histological evaluation, included staining affinity, cellular outline, cytoplasmic and nuclear attributes, and overall tissue structure, was conducted by a panel of academic experts and rated using a scale of poor (1), fair (2), good (3), very good (4), and excellent (5) grades. The data were later statistically analyzed to determine the significant differences among the tested fixative types. A higher penetration rate was observed with the EZAT solution at 6 and 12 hours' time and the samples reached optimal fixation after 24 hours; with an accelerated diffusion coefficient, and a minimal shrinking effect compared to formalin 10% and NBF. The microscopic evaluation of hematoxylin/eosin-stained sections revealed better staining affinity, refined histological details, and enhanced cytoplasmic and nuclear properties. The overall structural evaluation revealed an excellent microscopic appearance with the EZAT solution compared to formalin-based fixatives. The EZAT fixative should be considered as an everyday preservative in histology and histopathology laboratories. Future studies should be focused on the potential of EZAT in cellular histochemistry and immunohistochemistry practices.

Creation of a microsurgical neuroanatomy laboratory and virtual operating room: a preliminary study.

A comprehensive understanding of microsurgical neuroanatomy, familiarity with the operating room environment, patient positioning in relation to the surgery, and knowledge of surgical approaches is crucial in neurosurgical education. However, challenges such as limited patient exposure, heightened patient safety concerns, a decreased availability of surgical cases during training, and difficulties in accessing cadavers and laboratories have adversely impacted this education. Three-dimensional (3D) models and augmented reality (AR) applications can be utilized to depict the cortical and white matter anatomy of the brain, create virtual models of patient surgical positions, and simulate the operating room and neuroanatomy laboratory environment. Herein, the authors, who used a single application, aimed to demonstrate the creation of 3D models of anatomical cadaver dissections, surgical approaches, patient surgical positions, and operating room and laboratory designs as alternative educational materials for neurosurgical training. A 3D modeling application (Scaniverse) was employed to generate 3D models of cadaveric brain specimens and surgical approaches using photogrammetry. It was also used to create virtual representations of the operating room and laboratory environment, as well as the surgical positions of patients, by utilizing light detection and ranging (LiDAR) sensor technology for accurate spatial mapping. These virtual models were then presented in AR for educational purposes. Virtual representations in three dimensions were created to depict cadaver specimens, surgical approaches, patient surgical positions, and the operating room and laboratory environment. These models offer the flexibility of rotation and movement in various planes for improved visualization and understanding. The operating room and laboratory environment were rendered in three dimensions to create a simulation that could be navigated using AR and mixed reality technology. Realistic cadaveric models with intricate details were showcased on internet-based platforms and AR platforms for enhanced visualization and learning. The utilization of this cost-effective, straightforward, and readily available approach to generate 3D models has the potential to enhance neuroanatomical and neurosurgical education. These digital models can be easily stored and shared via the internet, making them accessible to neurosurgeons worldwide for educational purposes.

Brain tropism acquisition: The spatial dynamics and evolution of a measles virus collective infectious unit that drove lethal subacute sclerosing panencephalitis.

It is increasingly appreciated that pathogens can spread as infectious units constituted by multiple, genetically diverse genomes, also called collective infectious units or genome collectives. However, genetic characterization of the spatial dynamics of collective infectious units in animal hosts is demanding, and it is rarely feasible in humans. Measles virus (MeV), whose spread in lymphatic tissues and airway epithelia relies on collective infectious units, can, in rare cases, cause subacute sclerosing panencephalitis (SSPE), a lethal human brain disease. In different SSPE cases, MeV acquisition of brain tropism has been attributed to mutations affecting either the fusion or the matrix protein, or both, but the overarching mechanism driving brain adaptation is not understood. Here we analyzed MeV RNA from several spatially distinct brain regions of an individual who succumbed to SSPE. Surprisingly, we identified two major MeV genome subpopulations present at variable frequencies in all 15 brain specimens examined. Both genome types accumulated mutations like those shown to favor receptor-independent cell-cell spread in other SSPE cases. Most infected cells carried both genome types, suggesting the possibility of genetic complementation. We cannot definitively chart the history of the spread of this virus in the brain, but several observations suggest that mutant genomes generated in the frontal cortex moved outwards as a collective and diversified. During diversification, mutations affecting the cytoplasmic tails of both viral envelope proteins emerged and fluctuated in frequency across genetic backgrounds, suggesting convergent and potentially frequency-dependent evolution for modulation of fusogenicity. We propose that a collective infectious unit drove MeV pathogenesis in this brain. Re-examination of published data suggests that similar processes may have occurred in other SSPE cases. Our studies provide a primer for analyses of the evolution of collective infectious units of other pathogens that cause lethal disease in humans.

Cerebral vascular and blood brain-barrier abnormalities in a mouse model of epilepsy and tuberous sclerosis complex.

Tuberous sclerosis complex (TSC) is a genetic disorder, characterized by tumor formation in the brain and other organs, and severe neurological symptoms, such as epilepsy. Abnormal vascular endothelial growth factor (VEGF) expression may promote angiogenesis in kidney and lung tumors in TSC and has been identified in brain specimens from TSC patients, but the role of VEGF and vascular abnormalities in neurological manifestations of TSC is poorly defined. In this study, we investigated abnormalities in brain VEGF expression, cerebral blood vessel anatomy, and blood-brain barrier (BBB) structure and function in a mouse model of TSC. Tsc1GFAP CKO mice were used to investigate VEGF expression and vascular abnormalities in the brain by Western blotting and immunohistochemical analysis of vascular and BBB markers. Invivo two-photon imaging was used to assess BBB permeability to normally impenetrable fluorescently labeled compounds. The effect of mechanistic target of rapamycin (mTOR) pathway inhibitors, VEGF receptor antagonists (apatinib), or BBB stabilizers (RepSox) was assessed in some of these assays, as well as on seizures by video-electroencephalography. VEGF expression was elevated in cortex of Tsc1GFAP CKO mice, which was reversed by the mTOR inhibitor rapamycin. Tsc1GFAP CKO mice exhibited increased cerebral angiogenesis and vascular complexity in cortex and hippocampus, which were reversed by the VEGF receptor antagonist apatinib. BBB permeability was abnormally increased and BBB-related tight junction proteins occludin and claudin-5 were decreased in Tsc1GFAP CKO mice, also in an apatinib- and RepSox-dependent manner. The BBB stabilizer (RepSox), but not the VEGF receptor antagonist (apatinib), decreased seizures and improved survival in Tsc1GFAP CKO mice. Increased brain VEGF expression is dependent on mTOR pathway activation and promotes cerebral vascular abnormalities and increased BBB permeability in a mouse model of TSC. BBB modulation may affect epileptogenesis and represent a rational treatment for epilepsy in TSC.

High performance mass spectrometry reveals possible kerogen substructures in persistent ancient human brain

The recovery of visually recognizable brain masses from skeletonized human burials is rare; the discovery of an exceptionally well-preserved 2500-year-old brain during excavations at Heslington, Yorkshire, UK, therefore attracted international publicity. Analysis of a lipidic extract of that brain material showed the presence of high molecular weight organic components. To determine whether the presence of such compounds is a common feature of unusually preserved brain specimens, we have carried out high resolution matrix-assisted laser desorption/ionization Fourier transform ion-cyclotron resonance mass spectrometric (MALDI FT-ICR-MS) analyses of lipidic extracts of preserved brain remains from 14 contexts, obtained from four archaeological sites ranging from 200 to 2500 years old. These data allowed elemental formulae for the predominant signals in the resulting spectra to be generated, and a detailed comparison of the resulting very rich dataset was carried out, allowing 38 molecular formulae to be assigned. The components identified across all the sample extracts analysed fell into the same class of large organic molecules as those from the Heslington brain and are generally functionalized with low numbers of heteroatoms (oxygen, nitrogen, or both). These components do not correspond to those identified in adipocere, but instead resemble kerogen substructures, surprisingly formed over historic rather than geological timescales. The presence of such insoluble, inert structures would help explain why brain material in which they are found is persistent. Our results pave the way for further analyses aimed at understanding the processes that take place when brain material is preserved in the archaeological record.

Relationship between metabolic disease and Alzheimer’s disease

AbstractBackgroundDiabetes is an enormous and growing global public health problem, associated with poor health outcomes including dementia. Mechanisms underlying the relationship of diabetes to dementia are less well understood.MethodsWe leveraged several large, ongoing community‐based cohorts of older women and men with and without diabetes, taking part in longitudinal, clinical‐pathologic studies of aging at the Rush Alzheimer’s Disease Center. Participants undergo annual clinical evaluations including detailed neuropsychological testing, and brain autopsy at time of death. We examined the relation of diabetes and related clinical variables (e.g., medications, body mass index [BMI], hypertension), and blood and brain biomarkers of insulin resistance and other measures (e.g., epigenetics), to brain outcomes. Level and change in global cognition and five cognitive domains were based on neuropsychological tests, and dementia status was classified. Postmortem human brain specimens of deceased persons were systematically evaluated for neuropathology, including neurodegenerative (e.g., Alzheimer’s disease [AD]) and cerebrovascular disease (e.g., infarcts).ResultsDiabetes, present in 15‐20% of our cohorts, is associated a two‐fold increased risk of dementia and relates to cognitive decline (particularly in some cognitive domains more than others), and these observations are found in both Black and White participants. Some diabetes‐related clinical variables (e.g., BMI) are associated with faster cognitive decline, while others such as medications (metformin) are associated with slower cognitive decline. Regarding human postmortem neuropathologic outcomes, diabetes is associated with cerebrovascular pathologies, and small subcortical infarcts in particular. But, while we have not found clear associations of diabetes with neurodegenerative pathologies such as AD, some brain molecular markers in the insulin signaling pathway (AKT1) are associated with AD (including amyloid‐beta and tau tangles) and cognition (memory). Recently, using blood and brain specimens, we show that genome‐wide 5‐hydroxymethylcytosine profiling uncovers epigenetic features and biologic pathways related to nucleotide sugar metabolism linking diabetes to diabetes‐associated AD.ConclusionDiabetes is a potentially‐modifiable risk factor for dementia and cognitive decline. Clinical, neuropathologic, and epigenetic factors are at play in the underlying mechanisms. A better understanding of mechanisms will inform future research and offer opportunities for precision medicine and dementia prevention (supported by NIH: R01NS084965, RF1AG059621, RF1AG074549, R01AG022018, P30AG10161, P30AG072975, R01AG15819, R01AG17917).

Clinical value of CSF TMEM106B in familial and sporadic frontotemporal lobar degeneration

AbstractBackgroundTMEM106B, a lysosomal trafficking protein, is an important genetic susceptibility risk factor for frontotemporal lobar degeneration (FTLD). In GRN mutation carriers, minor allele homozygosity in the TMEM106B rs1990622 SNP modulates the risk of FTLD. TMEM106B is often the main component of amyloid fibrils in FTLD with TDP43 aggregates. TMEM106B has been quantified in human brain specimens, but its role as a fluid biomarker is unknown. Here, we investigate the clinical value of CSF TMEM106B in FTLD.MethodsCSF TMEM106B was quantified with SOMAmer proteomics (v3.0, SomaLogic®) in an original cohort of C9orf72, GRN and MAPT symptomatic and asymptomatic mutation carriers and family non‐carrier controls, recruited through ALLFTD (n = 182), and a validation cohort of sporadic neuropathology‐confirmed FTLD‐tau and FTLD‐TDP43, clinically‐diagnosed progressive supranuclear palsy – Richardson syndrome (PSP‐RS) and age‐matched controls (n = 96). CSF TMEM106B was correlated with disease severity, measured by the Frontotemporal Lobar Degeneration module global scores (CDR+NACC/FTLD); brain volume, measured with Bayesian linear mixed‐effect modeling, using age, sex and total‐intracranial volume‐corrected permutations with threshold‐free cluster enhancement; and CSF neurofilament light chain (NfL) measured with Simoa. TMEM106B SOMAmer specificity was validated in cell culture overexpression systems and human brain specimens with high TMEM106B burden.ResultsIn both cohorts, there were no differences in CSF TMEM106B by sex, phenotype or neuropathological diagnosis, except for lower levels in PSP‐RS compared to controls (‐0.31 Log2‐fold change, p < 0.001). CSF TMEM106B did not correlate with age. Regardless of disease‐causing mutation, lower CSF TMEM106B was associated with worse disease severity (Figure 1 and 2). CSF TMEM106B was lower in homozygous TMEM106B rs1990622 protective allelein C9orf2 and MAPT, but not in GRN mutation carriers (Figures 3). CSF TMEM106B showed a trend for inverse correlation with NfL in the whole sample (r = ‐0.135, p = 0.052), and correlated positively with left frontal volume in symptomatic FTLD mutation gene carriers (p < 0.05).ConclusionCSF TMEM106B is quantifiable in CSF in vivo. CSF TMEM106B levels are affected by an interaction of disease severity and FTLD and TMEM106B genotypes. Further work is needed to determine its value as a clinical biomarker.

Transformation of non-neuritic into neuritic plaques during AD progression drives cortical spread of tau pathology via regenerative failure

Extracellular amyloid-β (Aβ) plaques and intracellular aggregates of tau protein in form of neurofibrillary tangles (NFT) are pathological hallmarks of Alzheimer’s disease (AD). The exact mechanism how these two protein aggregates interact in AD is still a matter of debate. Neuritic plaques (NP), a subset of Aβ plaques containing dystrophic neurites (DN), are suggested to be unique to AD and might play a role in the interaction of Aβ and tau. Quantifying NP and non-NP in postmortem brain specimens from patients with increasing severity of AD neuropathological changes (ADNC), we demonstrate that the total number of Aβ plaques and NP increase, while the number of non-NP stagnates. Furthermore, investigating the correlation between NP and NFT, we identified unexpected brain region-specific differences when comparing cases with increasingly more severe ADNC. In neocortical regions NFT counts increase in parallel with NP counts during the progression of ADNC, while this correlation is not observed in hippocampus. These data support the notion that non-NP are transformed into NP during the progression of ADNC and indicate that NP might drive cortical NFT formation. Next, using spatial transcriptomics, we analyzed the gene expression profile of the microenvironment around non-NP and NP. We identified an upregulation of neuronal systems and Ca-dependent event pathways around NP compared to non-NP. We speculate that the upregulation of these transcripts may hint at a compensatory mechanism underlying NP formation. Our studies suggest that the transformation of non-NP to NP is a key event in ADNC progression and points to regenerative failure as a potential driving force of this process.

Brain Pathways in LIS1-Associated Lissencephaly Revealed by Diffusion MRI Tractography.

Lissencephaly (LIS) is a rare neurodevelopmental disorder with severe symptoms caused by abnormal neuronal migration during cortical development. It is caused by both genetic and non-genetic factors. Despite frequent studies about the cortex, comprehensive elucidation of structural abnormalities and their effects on the white matter is limited. The main objective of this study is to analyze abnormal neuronal migration pathways and white matter fiber organization in LIS1-associated LIS using diffusion MRI (dMRI) tractography. For this purpose, slabs of brain specimens with LIS (n = 3) and age and sex-matched controls (n = 4) were scanned with 3T dMRI. Our high-resolution ex vivo dMRI successfully identified common abnormalities across the samples. The results revealed an abnormal increase in radially oriented subcortical fibers likely associated with radial migration pathways and u-fibers and a decrease in association fibers in all LIS specimens.

Neuroanatomy in virtual reality: Development and pedagogical evaluation of photogrammetry-based 3D brain models.

Anatomy studies are an essential part of medical training. The study of neuroanatomy in particular presents students with a unique challenge of three-dimensional spatial understanding. Virtual Reality (VR) has been suggested to address this challenge, yet the majority of previous reports have implemented computer-generated or imaging-based models rather than models of real brain specimens. Using photogrammetry of real human bodies and advanced editing software, we developed 3D models of a real human brain at different stages of dissection. Models were placed in a custom-built virtual laboratory, where students can walk around freely, explore, and manipulate (i.e., lift the models, rotate them for different viewpoints, etc.). Sixty participants were randomly assigned to one of three learning groups: VR, 3D printed models or read-only, and given 1 h to study the white matter tracts of the cerebrum, followed by theoretical and practical exams and a learning experience questionnaire. We show that following self-guided learning in virtual reality, students demonstrate a gain in spatial understanding and an increased satisfaction with the learning experience, compared with traditional learning approaches. We conclude that the models and virtual lab described in this work may enhance learning experience and improve learning outcomes.

EXTH-10. QUAD-DM1: A HIGHLY POTENT DRUG CONJUGATE FOR BREAST CANCER AND BREAST CANCER BRAIN METASTASIS TREATMENT

Abstract Triple-negative breast cancer (TNBC) remains an unmet need in medicine. Previously, we and others found that interleukin 13 receptor alpha 2 (IL-13RA2), EphA2, EphA3 and EphB2 receptors are over-expressed in almost all patients with glioblastoma (GBM). We performed a first-of-a-kind Phase I clinical trial in dogs with spontaneous gliomas using a cocktail of cytotoxins targeting IL-13RA2 and EphA2 receptor. The majority of dogs experienced >50% of tumor regression; four dogs exhibited >92% tumor shrinkage and several dogs became long-term survivors. Next, we pursued the novel idea of targeting four tumor-associated receptors, instead of two, with one pharmaceutical compound. To this end, we produced a multivalent ligand, termed QUAD. More recently, we found that a conjugate of QUAD with emtansine (DM1), a microtubule-disrupting agent, demonstrated a specific killing potency on GBM cells, in low picomolar range. Unexpectedly, we observed that human breast cancer cells are also highly responsive to this drug candidate. We thus examined the presence of the four receptors in breast cancer cells and tissue micro-arrays, including involved lymph nodes, and in paired primary tumor - brain metastases, spanning two molecular subtypes of breast cancer: TNBC and HER2+. We found that the four targeted receptors are expressed in almost all breast cancer and related metastases to brain specimens, based on the expression levels for the genes and the gene products. Furthermore, the breast cancer cell lines like HC1806, MDA-MB-468, MDA-MB-231, BT549, and the breast metastatic cell line MDA-MB-231-BRM cells are killed at up to picomolar concentrations of QUAD-DM1. MDA-MB-231 tumors growing in mammary pads of athymic mice responded significantly to QUAD-DM1 given intravenously; QUAD recognizes murine receptors similarly to human. Thus, QUAD-DM1 is a novel type of a multivalent drug conjugate for the treatment of breast cancer and its brain metastases, which is applicable, but not exclusively, to TNBC.

High-resolution open-top axially swept light sheet microscopy

BackgroundOpen-top light-sheet microscopy (OT-LSM) is a specialized microscopic technique for the high-throughput cellular imaging of optically cleared, large-sized specimens, such as the brain. Despite the development of various OT-LSM techniques, achieving submicron resolution in all dimensions remains.ResultsWe developed a high-resolution open-top axially swept LSM (HR-OTAS-LSM) for high-throughput and high-resolution imaging in all dimensions. High axial and lateral resolutions were achieved by using an aberration-corrected axially swept excitation light sheet in the illumination arm and a high numerical aperture (NA) immersion objective lens in the imaging arm, respectively. The high-resolution, high-throughput visualization of neuronal networks in mouse brain and retina specimens validated the performance of HR-OTAS-LSM.ConclusionsThe proposed HR-OTAS-LSM method represents a significant advancement in the high-resolution mapping of cellular networks in biological systems such as the brain and retina.

Epigenetics of Autism Spectrum Disorders: A Multi-level Analysis Combining Epi-signature, Age Acceleration, Epigenetic Drift and Rare Epivariations Using Public Datasets.

Epigenetics of Autism Spectrum Disorders (ASD) is still an understudied field. The majority of the studies on the topic used an approach based on mere classification of cases and controls. The present study aimed at providing a multi-level approach in which different types of epigenetic analysis (epigenetic drift, age acceleration) are combined. We used publicly available datasets from blood (n = 3) and brain tissues (n = 3), separately. Firstly, we evaluated for each dataset and meta-analyzed the differential methylation profile between cases and controls. Secondly, we analyzed age acceleration, epigenetic drift and rare epigenetic variations. We observed a significant epi-signature of ASD in blood but not in brain specimens. We did not observe significant age acceleration in ASD, while epigenetic drift was significantly higher compared to controls. We reported the presence of significant rare epigenetic variations in 41 genes, 35 of which were never associated with ASD. Almost all genes were involved in pathways linked to ASD etiopathogenesis (i.e., neuronal development, mitochondrial metabolism, lipid biosynthesis and antigen presentation). Our data support the hypothesis of the use of blood epi-signature as a potential tool for diagnosis and prognosis of ASD. The presence of an enhanced epigenetic drift, especially in brain, which is linked to cellular replication, may suggest that alteration in epigenetics may occur at a very early developmental stage (i.e., fetal) when neuronal replication is still high.

Perceptions of Selected Undergraduate Medical Students in the Philippines on the Effectiveness of the Combined Use of Plastinated and Formalin-preserved Brains in Neuroanatomy Education: A Cross-sectional Study.

Neuroanatomy is both terrifying to learn and problematic to teach, and the different methods of neuroanatomical education have their own strengths and weaknesses. In this cross-sectional study, we evaluated the perception of undergraduate medical students towards the combined use of plastinated and formalin-preserved brain specimen in their neuroanatomy course. A bridging program was designed for students whose medical education was interrupted by the COVID-19 pandemic in order to reinforce the knowledge and understanding of anatomy that they acquired in a virtual environment. A total of 175 first year medical students participated in this learning activity, which included seven stations in neuroanatomy spread across two hours, and covered the anatomy of the circle of Willis, brainstem, cranial nerves, spinal cord, internal cerebrum, and external cerebrum. To evaluate short-term learning, the students were asked to take a quiz containing 10 multiple-choice questions before and after the learning activity. In addition, the students also answered a survey containing 11 Likert-type questions asking about their perception of the learningactivity. Following the learning activity, mean test scores increased from 4.73 (SD 1.74) to 5.32 (SD 1.52; mean difference 0.59, p = 0.008). Majority of the students (mean 81%, range 43-93%) had a neutral or positive perception of plastinated brain specimen, and on factor analysis, plastinated brain specimen were found to be both practical and useful for learning neuroanatomy. However, the participants perceived plastinated brain specimen alone to be insufficient for learning neuroanatomy, and a multimodal approach to learning neuroanatomy is ideal. Plastinated brain specimens were found to be an effective complement to formalin-preserved brain, and these should be used by medical schools when designing neuroanatomy learning activities for their students.

Frequencies of 4 tumor-infiltrating lymphocytes potently predict survival in glioblastoma, an immune desert.

GBM is an aggressive grade 4 primary brain tumor (BT), with a 5%-13% 5-year survival. Most human GBMs manifest as immunologically "cold" tumors or "immune deserts," yet the promoting or suppressive roles of specific lymphocytes within the GBM tumor microenvironment (TME) is of considerable debate. We used meticulous multiparametric flow cytometry (FC) to determine the lymphocytic frequencies in 102 GBMs, lower-grade gliomas, brain metastases, and nontumorous brain specimen. FC-attained frequencies were compared with frequencies estimated by "digital cytometry." The FC-derived data were combined with the patients' demographic, clinical, molecular, histopathological, radiological, and survival data. Comparison of FC-derived data to CIBERSORT-estimated data revealed the poor capacity of digital cytometry to estimate cell frequencies below 0.2%, the frequency range of most immune cells in BTs. Isocitrate dehydrogenase (IDH) mutation status was found to affect TME composition more than the gliomas' pathological grade. Combining FC and survival data disclosed that unlike other cancer types, the frequency of helper T cells (Th) and cytotoxic T lymphocytes (CTL) correlated negatively with glioma survival. In contrast, the frequencies of γδ-T cells and CD56bright natural killer cells correlated positively with survival. A composite parameter combining the frequencies of these 4 tumoral lymphocytes separated the survival curves of GBM patients with a median difference of 10 months (FC-derived data; P < .0001, discovery cohort), or 4.1 months (CIBERSORT-estimated data; P = .01, validation cohort). The frequencies of 4 TME lymphocytes strongly correlate with the survival of patients with GBM, a tumor considered an immune desert.

Determination of causes of adult deaths using minimally invasive tissue sampling in Gandaki province of Nepal: a multicenter hospital-based study

BackgroundMinimally Invasive Tissue Sampling (MITS) has been successfully used to establish the cause of death in low- and middle-income countries, mostly in stillbirths and neonates. The objective of this study was to determine the causes of death among adults using MITS in the Gandaki province of Nepal and to find out the contribution of MITS to identify the causes of death.MethodsA multicentric hospital-based pilot study was conducted to enroll 100 cases of adult deaths. The specimens of cerebrospinal fluid, blood, brain, lungs, and liver tissue were collected utilizing MITS. These specimens underwent standard histopathological, serological, and microbiological analyses. The findings from MITS, and if available, clinical records and forensic autopsy findings were compiled and the cause of death panel identified the causes of death. The final cause of death allocated to each case was based on the WHO International Medical Certificate of Death.ResultsAmong a total of 100 cases enrolled during the study period, infectious cause attributed to the immediate cause of death in 77 (77%), cardiovascular in 10 (10%), neurological in 8 (8%), malignancy in two (2%), and gastrointestinal and hepatobiliary cause in one (1%) case. The mean age of the cases was 50.8 ± 15.9 years and 76 (76%) were males. MITS established the cause of death in the causal chain of events in 81(81%) cases and identified the cause of death significantly more with infectious than non-infectious causes (p < 0.001).ConclusionsMITS was useful in establishing the cause of death in the majority of adult deaths and the most common cause was infectious disease. Our findings suggest that MITS can be a valuable and alternative tool for mortality surveillance in low-resource settings, where complete diagnostic autopsies are less accepted or less prioritized.

Mapping the individual human cortex using multidimensional MRI and unsupervised learning.

Human evolution has seen the development of higher-order cognitive and social capabilities in conjunction with the unique laminar cytoarchitecture of the human cortex. Moreover, early-life cortical maldevelopment has been associated with various neurodevelopmental diseases. Despite these connections, there is currently no noninvasive technique available for imaging the detailed cortical laminar structure. This study aims to address this scientific and clinical gap by introducing an approach for imaging human cortical lamina. This method combines diffusion-relaxation multidimensional MRI with a tailored unsupervised machine learning approach that introduces enhanced microstructural sensitivity. This new imaging method simultaneously encodes the microstructure, the local chemical composition and importantly their correlation within complex and heterogenous tissue. To validate our approach, we compared the intra-cortical layers obtained using our ex vivo MRI-based method with those derived from Nissl staining of postmortem human brain specimens. The integration of unsupervised learning with diffusion-relaxation correlation MRI generated maps that demonstrate sensitivity to areal differences in cytoarchitectonic features observed in histology. Significantly, our observations revealed layer-specific diffusion-relaxation signatures, showing reductions in both relaxation times and diffusivities at the deeper cortical levels. These findings suggest a radial decrease in myelin content and changes in cell size and anisotropy, reflecting variations in both cytoarchitecture and myeloarchitecture. Additionally, we demonstrated that 1D relaxation and high-order diffusion MRI scalar indices, even when aggregated and used jointly in a multimodal fashion, cannot disentangle the cortical layers. Looking ahead, our technique holds the potential to open new avenues of research in human neurodevelopment and the vast array of disorders caused by disruptions in neurodevelopment.

Microstructural Neurodegeneration of the Entorhinal-Hippocampus Pathway along the Alzheimer's Disease Continuum.

Conventional neuroimaging biomarkers for the neurodegeneration of Alzheimer's disease (AD) are not sensitive enough to detect neurodegenerative alterations during the preclinical stage of AD individuals. We examined whether neurodegeneration of the entorhinal-hippocampal pathway could be detected along the AD continuum using ultra-high-field diffusion tensor imaging and tractography for ex vivo brain tissues. Postmortem brain specimens from a cognitively unimpaired individual without AD pathological changes (non-AD), a cognitively unimpaired individual with AD pathological changes (preclinical AD), and a demented individual with AD pathological changes (AD dementia) were scanned with an 11.7T diffusion magnetic resonance imaging. Fractional anisotropy (FA) values of the entorhinal layer II and number of perforant path fibers counted by tractography were compared among the AD continuum. Following the imaging analyses, the status of myelinated fibers and neuronal cells were verified by subsequent serial histological examinations. At 250μm (zipped to 125μm) isotropic resolution, the entorhinal layer II islands and the perforant path fibers could be identified in non-AD and preclinical AD, but not in AD dementia, followed by histological verification. The FA value of the entorhinal layer II was the highest among the entorhinal laminae in non-AD and preclinical AD, whereas the FA values in the entorhinal laminae were homogeneously low in AD dementia. The FA values and number of perforant path fibers decreased along the AD continuum (non-AD>preclinical AD > AD dementia). We successfully detected neurodegenerative alterations of the entorhinal-hippocampal pathway at the preclinical stage of the AD continuum.