Pathologic classification of a late-onset peripheral neuropathy in a spontaneous Labrador retriever dog model.

Late-onset peripheral neuropathy (LPN) is a heritable canine neuropathy commonly found in Labrador retrievers and is characterized by laryngeal paralysis and pelvic limb paresis. Our objective was to establish canine LPN as a model for human hereditary peripheral neuropathy by classifying it as either an axonopathy or myelinopathy and evaluating length-dependent degeneration. We conducted a motor nerve conduction study of the sciatic and ulnar nerves, electromyography (EMG) of appendicular and epaxial musculature, and histologic analysis of sciatic and recurrent laryngeal nerves in LPN-affected and control dogs. LPN-affected dogs exhibited significant decreases in compound muscle action potential (CMAP) amplitude, CMAP area, and pelvic limb latencies. However, no differences were found in motor nerve conduction velocity, residual latencies, or CMAP duration. Distal limb musculature showed greater EMG changes in LPN-affected dogs. Histologically, LPN-affected dogs exhibited a reduction in the number of large-diameter axons, especially in distal nerve regions. In conclusion, LPN in Labrador retrievers is a common, spontaneous, length-dependent peripheral axonopathy that is a novel animal model of age-related peripheral neuropathy that could be used for fundamental research and clinical trials.

Association between military service and Alzheimer's disease neuropathology at autopsy.

INTRODUCTION: Anti-amyloid therapies are at the forefront of efforts to treat Alzheimer's disease (AD). Identifying amyloid risk factors may aid screening and intervention strategies. While veterans face increased exposure to risk factors, whether they face a greater neuropathologic amyloid burden is not well understood. METHODS: Male decedents donating to two Alzheimer's Disease Research Center (ADRC) brain banks from 1986 to 2018 with categorized neuritic plaque density and neurofibrillary tangles (n = 597) were included. Using generalized ordered logistic regression we modeled each outcome's association with military history adjusting for age and death year. RESULTS: Having served in the military (60% of sample) is associated with post mortem neuritic amyloid plaque (for each comparison of higher to lower C scores OR = 1.26; 95% confidence interval [CI] = 1.06-1.49) and tau pathology (B score OR = 1.10; 95% CI = 1.08-1.12). DISCUSSION: This is the first study, to our knowledge, finding increased levels of verified AD neuropathology in those with military service. Targeted veteran AD therapies is a pressing need.

FABP7 drives an inflammatory response in human astrocytes and is upregulated in Alzheimer's disease.

Alzheimer's disease (AD), the most common cause of dementia in the elderly, is characterized by the accumulation of intracellular neurofibrillary tangles, extracellular amyloid plaques, and neuroinflammation. In partnership with microglial cells, astrocytes are key players in the regulation of neuroinflammation. Fatty acid binding protein 7 (FABP7) belongs to a family of conserved proteins that regulate lipid metabolism, energy homeostasis, and inflammation. FABP7 expression is largely restricted to astrocytes and radial glia-like cells in the adult central nervous system. We observed that treatment of primary hippocampal astrocyte cultures with amyloid ß fragment 25-35 (Aß25-35) induces FABP7 upregulation. In addition, FABP7 expression is upregulated in the brain of APP/PS1 mice, a widely used AD mouse model. Co-immunostaining with specific astrocyte markers revealed increased FABP7 expression in astrocytes. Moreover, astrocytes surrounding amyloid plaques displayed increased FABP7 staining when compared to non-plaque-associated astrocytes. A similar result was obtained in the brain of AD patients. Whole transcriptome RNA sequencing analysis of human astrocytes differentiated from induced pluripotent stem cells (i-astrocytes) overexpressing FABP7 identified 500 transcripts with at least a 2-fold change in expression. Gene Ontology enrichment analysis identified (i) positive regulation of cytokine production and (ii) inflammatory response as the top two statistically significant overrepresented biological processes. We confirmed that wild-type FABP7 overexpression induces an NF-κB-driven inflammatory response in human i-astrocytes. On the other hand, the expression of a ligand-binding impaired mutant FABP7 did not induce NF-κB activation. Together, our results suggest that the upregulation of FABP7 in astrocytes could contribute to the neuroinflammation observed in AD.

A Rare Case of Precocious Puberty Secondary to an LH-secreting Pituitary Adenoma.

An 8-year, 7-month-old male presented with puberty symptoms, including a 1.5-year history of facial hair with 9 months of phallic growth, body odor, and acne. Physical examination revealed phallic enlargement but only 4 mL testes bilaterally. Laboratory evaluation revealed markedly elevated LH and testosterone, but a prepubertal FSH level and minimally elevated adrenal androgens. A magnetic resonance imaging scan of the head revealed an anterior pituitary adenoma, and after the patient failed to respond to leuprolide, he was initiated on spironolactone and anastrozole to minimize pubertal progression before transsphenoidal adenomectomy. Postoperatively, the patient had rapid reduction of LH and testosterone, with subsequent cessation of pubertal progression, confirming the diagnosis of an LH-secreting pituitary adenoma despite negative immunoreactivity for LH and FSH. Functioning gonadotroph adenomas are rare and have been documented only in small case series and case reports. When active, these most commonly secrete FSH or co-secrete FSH and LH, and only very rarely result in precocious puberty. Here, we describe a rare case of an isolated LH-secreting functioning gonadotroph adenoma resulting in precocious puberty. This case reinforces the need to critically analyze departures from the typical pubertal sequence and to expand one's differential to include etiologies that can cause unbalanced secretion of gonadotropins.

Malignant Transformation of Recurrent Residual Cerebellopontine Angle Epidermoid Tumor: Significance of Clinical Vigilance and Long-Term Surveillance.

Epidermoid tumors (ET) are slow-growing masses where malignant transformations occur extremely rarely. Malignant transformation warning signs are the rapid-onset, progression, and recurrence of symptoms. The radiologic evidence for malignant transformation is contrast enhancement with rapid growth, observed with magnetic resonance imaging (MRI) or computed tomography scans. Here, we provide a case report of a 68-year-old woman with a long-standing history of left-sided cerebellopontine angle ET who presented with a recent worsening of symptoms, and MRI observation of new ET contrast enhancement. Surgical re-exploration and histopathologic confirmation are mandatory in this setting of recent symptom worsening and MRI observation of rapid mass growth.

Brachial plexus anatomy in the miniature swine as compared to human.

Brachial plexus injury (BPI) occurs when the brachial plexus is compressed, stretched, or avulsed. Although rodents are commonly used to study BPI, these models poorly mimic human BPI due to the discrepancy in size. The objective of this study was to compare the brachial plexus between human and Wisconsin Miniature SwineTM (WMSTM ), which are approximately the weight of an average human (68-91 kg), to determine if swine would be a suitable model for studying BPI mechanisms and treatments. To analyze the gross anatomy, WMS brachial plexuses were dissected both anteriorly and posteriorly. For histological analysis, sections from various nerves of human and WMS brachial plexuses were fixed in 2.5% glutaraldehyde, and postfixed with 2% osmium tetroxide. Subsequently paraffin sections were counter-stained with Masson's Trichrome. Gross anatomy revealed that the separation into three trunks and three cords is significantly less developed in the swine than in human. In swine, it takes the form of upper, middle, and lower systems with ventral and dorsal components. Histological evaluation of selected nerves revealed differences in nerve trunk diameters and the number of myelinated axons in the two species. The WMS had significantly fewer myelinated axons than humans in median (p = 0.0049), ulnar (p = 0.0002), and musculocutaneous nerves (p = 0.0454). The higher number of myelinated axons in these nerves for humans is expected because there is a high demand of fine motor and sensory functions in the human hand. Due to the stronger shoulder girdle muscles in WMS, the WMS suprascapular and axillary nerves were larger than in human. Overall, the WMS brachial plexus is similar in size and origin to human making them a very good model to study BPI. Future studies analyzing the effects of BPI in WMS should be conducted.

Rhesus monkeys as a translational model for late-onset Alzheimer's disease.

Age is a major risk factor for late-onset Alzheimer's disease (AD) but seldom features in laboratory models of the disease. Furthermore, heterogeneity in size and density of AD plaques observed in individuals are not recapitulated in transgenic mouse models, presenting an incomplete picture. We show that the amyloid plaque microenvironment is not equivalent between rodent and primate species, and that differences in the impact of AD pathology on local metabolism and inflammation might explain established differences in neurodegeneration and functional decline. Using brain tissue from transgenic APP/PSEN1 mice, rhesus monkeys with age-related amyloid plaques, and human subjects with confirmed AD, we report altered energetics in the plaque microenvironment. Metabolic features included changes in mitochondrial distribution and enzymatic activity, and changes in redox cofactors NAD(P)H that were shared among species. A greater burden of lipofuscin was detected in the brains from monkeys and humans of advanced age compared to transgenic mice. Local inflammatory signatures indexed by astrogliosis and microglial activation were detected in each species; however, the inflamed zone was considerably larger for monkeys and humans. These data demonstrate the advantage of nonhuman primates in modeling the plaque microenvironment, and provide a new framework to investigate how AD pathology might contribute to functional loss.

MR1 overexpression correlates with poor clinical prognosis in glioma patients.

BACKGROUND: Glioblastoma is the most common adult primary brain tumor with near-universal fatality. Major histocompatibility complex (MHC) class I molecules are important mediators of CD8 activation and can be downregulated by cancer cells to escape immune surveillance. MR1 is a nonclassical MHC-I-like molecule responsible for the activation of a subset of T cells. Although high levels of MR1 expression should enhance cancer cell recognition, various tumors demonstrate MR1 overexpression with unknown implications. Here, we study the role of MR1 in glioma. METHODS: Using multi-omics data from the Cancer Genome Atlas (TCGA), we studied MR1 expression patterns and its impact on survival for various solid tumors. In glioma specifically, we validated MR1 expression by histology, elucidate transcriptomic profiles of MR1 high versus low gliomas. To understand MR1 expression, we analyzed the methylation status of the MR1 gene and MR1 gene-related transcription factor (TF) expression. RESULTS: MR1 is overexpressed in all grades of glioma and many other solid cancers. However, only in glioma, MR1 overexpression correlated with poor overall survival and demonstrated global dysregulation of many immune-related genes in an MR1-dependent manner. MR1 overexpression correlated with decreased MR1 gene methylation and upregulation of predicted MR1 promoter binding TFs, implying MR1 gene methylation might regulate MR1 expression in glioma. CONCLUSIONS: Our in silico analysis shows that MR1 expression is a predictor of clinical outcome in glioma patients and is potentially regulated at the epigenetic level, resulting in immune-related genes dysregulation. These findings need to be validated using independent in vitro and in vivo functional studies.

A Fatal Case of Powassan Virus Encephalitis.

Powassan virus (POWV) is a flavivirus of the tick-borne encephalitis serogroup that causes a rare and potentially life-threatening neuroinvasive disease. Viral transmission occurs during zoonotic spillover from mammals by the bite of an infected tick in endemic regions of North America. The number of reported POWV cases has recently increased in the United States. We report a fatal case of POWV meningoencephalomyelitis in Northern Wisconsin following a documented tick bite. Histologic examination of the brain demonstrated widespread intraparenchymal and perivascular lymphohistocytic infiltration, microglial nodule formation, and marked neuronal degeneration, most severely involving the substantia nigra, anterior horn of spinal cord and cerebellum. Although no viral inclusions were seen in routine light microscopy, electron microscopy identified multiple neurons containing cytoplasmic clusters of virus particles ∼50 nm in diameter. POWV infection was confirmed using immunohistochemical analysis and reverse transcription-polymerase chain reaction. This report demonstrates in detail regional central nervous system involvement and ultrastructural characteristics of Powassan viral particles by transmission electron microscopy, while highlighting the utility of evaluating fixed autopsy tissues in cases of unexplained meningoencephalomyelitis.

Comprehensive analysis of diverse low-grade neuroepithelial tumors with FGFR1 alterations reveals a distinct molecular signature of rosette-forming glioneuronal tumor.

The FGFR1 gene encoding fibroblast growth factor receptor 1 has emerged as a frequently altered oncogene in the pathogenesis of multiple low-grade neuroepithelial tumor (LGNET) subtypes including pilocytic astrocytoma, dysembryoplastic neuroepithelial tumor (DNT), rosette-forming glioneuronal tumor (RGNT), and extraventricular neurocytoma (EVN). These activating FGFR1 alterations in LGNET can include tandem duplication of the exons encoding the intracellular tyrosine kinase domain, in-frame gene fusions most often with TACC1 as the partner, or hotspot missense mutations within the tyrosine kinase domain (either at p.N546 or p.K656). However, the specificity of these different FGFR1 events for the various LGNET subtypes and accompanying genetic alterations are not well defined. Here we performed comprehensive genomic and epigenomic characterization on a diverse cohort of 30 LGNET with FGFR1 alterations. We identified that RGNT harbors a distinct epigenetic signature compared to other LGNET with FGFR1 alterations, and is uniquely characterized by FGFR1 kinase domain hotspot missense mutations in combination with either PIK3CA or PIK3R1 mutation, often with accompanying NF1 or PTPN11 mutation. In contrast, EVN harbors its own distinct epigenetic signature and is characterized by FGFR1-TACC1 fusion as the solitary pathogenic alteration. Additionally, DNT and pilocytic astrocytoma are characterized by either kinase domain tandem duplication or hotspot missense mutations, occasionally with accompanying NF1 or PTPN11 mutation, but lacking the accompanying PIK3CA or PIK3R1 mutation that characterizes RGNT. The glial component of LGNET with FGFR1 alterations typically has a predominantly oligodendroglial morphology, and many of the pilocytic astrocytomas with FGFR1 alterations lack the biphasic pattern, piloid processes, and Rosenthal fibers that characterize pilocytic astrocytomas with BRAF mutation or fusion. Together, this analysis improves the classification and histopathologic stratification of LGNET with FGFR1 alterations.

Attenuation Coefficient Parameter Computations for Tissue Composition Assessment of Carotid Atherosclerotic Plaque in Vivo.

Quantitative ultrasound has been used to assess carotid plaque tissue composition. Here, we compute the attenuation coefficient (AC) in vivo with the optimum power spectral shift estimator (OPSSE) and reference phantom method (RPM), extract AC parameters and form parametric maps. Differences between OPSSE and RPM AC parameters are computed. Relationships between AC parameters, surgical scores and histopathology assessments are examined. Kendall's τ correlations between OPSSE AC and surgical scores are significant, including those between cholesterol and Standard Deviation (adjusted p = 0.038); thrombus and Minimum (adjusted p = 0.002), Maximum (adjusted p = 0.021) and Standard Deviation (adjusted p = 0.001); ulceration and Average (adjusted p = 0.033), Median (unadjusted p = 0.013), Maximum (unadjusted p = 0.039) and Mode (adjusted p = 0.009). The strongest correlations with histopathology are percentage cholesterol and Median OPSSE (unadjusted p = 0.007); percentage hemorrhage and Minimum OPSSE (adjusted p < 0.001); hemosiderin score and Median OPSSE (adjusted p = 0.010); and percentage calcium and Percentage Non-physical RPM Pixels (unadjusted p = 0.014). Kruskal-Wallis H and Dunn's post hoc tests have the ability to distinguish between groups (p < 0.05). Results suggest AC parameters may assist in vivo evaluation of carotid plaque vulnerability.

Proteomic Atlas of the Human Brain in Alzheimer's Disease.

The brain represents one of the most divergent and critical organs in the human body. Yet, it can be afflicted by a variety of neurodegenerative diseases specifically linked to aging, about which we lack a full biomolecular understanding of onset and progression, such as Alzheimer's disease (AD). Here we provide a proteomic resource comprising nine anatomically distinct sections from three aged individuals, across a spectrum of disease progression, categorized by quantity of neurofibrillary tangles. Using state-of-the-art mass spectrometry, we identify a core brain proteome that exhibits only small variance in expression, accompanied by a group of proteins that are highly differentially expressed in individual sections and broader regions. AD affected tissue exhibited slightly elevated levels of tau protein with similar relative expression to factors associated with the AD pathology. Substantial differences were identified between previous proteomic studies of mature adult brains and our aged cohort. Our findings suggest considerable value in examining specifically the brain proteome of aged human populations from a multiregional perspective. This resource can serve as a guide, as well as a point of reference for how specific regions of the brain are affected by aging and neurodegeneration.

Pediatric extraosseous sacral chordoma: case report and literature review of embryonic derivation and clinical implications.

An extraosseous intradural presentation for a sacral chordoma in the pediatric age group has not been reported to date. This is a report on an 11-year-old boy who presented with an extraosseous, intradural sacral chordoma. He underwent gross-total resection and received adjuvant proton beam therapy. Neoplastic transformation of the notochord is reviewed to illustrate the developmental basis for the surgical anatomy and pathogenesis of the classic chordoma variant. Clinical and pathological features are reviewed to differentiate this chordoma presentation from classic osseous chordomas and ecchordosis physaliphora, a related benign developmental notochordal lesion. Finally, the role of developmental signaling in the pathogenesis of chordomas from postembryonic notochordal tissue is discussed.

Molecular Evolution of a Glioblastoma Controlled With Tumor Treating Fields and Concomitant Temozolomide.

Tumor Treating Field (TTFields) therapy has demonstrated efficacy in a Phase 3 study of newly diagnosed glioblastoma (GB) following radiation (RT) and temozolomide (TMZ). We report the appearance of an isolated satellite anterior temporal lobe lesion, 2 months post primary RT/TMZ directed at the primary GB (MGMT methylated) parietal lobe lesion and one adjuvant cycle of TMZ and TTFields. The mean RT dose delivered to the temporal lobe lesion was negligible, i.e., 4.53 ± 0.95 Gy. Mapping of the generated TTFields demonstrated that both lesions were encompassed by a field intensity in a therapeutic range. The temporal lobe lesion remained under the control of TTFields up to 12 months, at which point progression on a T1 contrast MRI resulted in surgery and a definitive diagnosis of GB without MGMT methylation. The primary parietal lobe at this time was in remission. Molecular sequencing on the GB tissue from multiple time points demonstrates clonal evolution of the cancer over time and in response to treatment.

Primary intracranial leiomyosarcoma in an immunocompetent patient: Case report and review of the literature.

Primary leiomyosarcoma is a rare tumor in the CNS, with few reported cases. Here, we describe a case of a primary intracranial leiomyosarcoma of the tentorium cerebelli. A 43-year-old woman presented with headache, acute vision loss, and difficulty speaking. MRI revealed a large heterogeneous-enhancing occipital mass, which was subsequently resected and diagnosed as a primary intracranial leiomyosarcoma. The patient went onto adjuvant radiotherapy delivering 60 Gy in 30 fractions. These tumors are exceedingly rare in immunocompetent individuals. We reviewed the 16 cases that have been reported in the literature. Surgical resection was the most common treatment (92%) with 53% receiving adjuvant radiation. There currently is no standard treatment regimen for intracranial leiomyosarcomas. Additional case reports that include descriptive treatment approaches with patient outcomes may help ascertain the best approach to treating these malignancies.

Neck Rhabdoid Tumors: Clinical Features and Consideration of Autologous Stem Cell Transplant.

Extrarenal malignant rhabdoid tumors (MRT) have a poor prognosis despite aggressive therapy. Adding high-dose chemotherapy with autologous stem cell rescue (HDC-ASCR) as consolidative therapy for MRT is controversial. We describe 2 patients, age 13 years and 19 months, with unresectable neck MRT. After chemotherapy and radiotherapy, both underwent HDC-ASCR and remain in remission over 4 years later. We reviewed all published cases of neck MRT, and found poorer outcomes and more variable age of presentation and time to progression than MRT at other sites. Neck MRT may represent a higher-risk subset of MRT, and addition of HDC-ASCR merits consideration.

Neurofibromatosis type 1: A neuro-psycho-cutaneous syndrome?

Neurofibromatosis type 1 (NF1) is an inherited disorder often associated with optic nerve gliomas, low-grade brain tumors, and readily visible signs. Though these features are frequently emphasized, the psychosocial and emotional morbidities are often overlooked. We present a patient with depressive disorder resulting in suicide in a patient with NF1.

Histopathologic Validation of Grayscale Carotid Plaque Characteristics Related to Plaque Vulnerability.

Inflammation and angiogenesis play major roles in carotid plaque vulnerability. The purpose of this study was to determine whether gray-scale features of carotid plaques are associated with histologic markers for inflammation. Thirty-eight individuals completed a dedicated research carotid ultrasound exam before carotid endarterectomy. Gray-scale analysis was performed on plaque images to measure plaque echogenicity (gray-scale median [GSM] pixel brightness), plaque area, presence of discrete white areas (DWAs) and the percent of black area near the lumen on any one component of the plaque. Plaques with higher ultrasound GSM had greater percent calcification (p = 0.013) on histopathology. Presence of an ultrasound DWA was associated with more plaque hemosiderin (p = 0.0005) and inflammation (p = 0.019) on histopathology examination. The percent of plaque black area in any one component was associated with a higher score for macroscopic ulceration (p = 0.028). Ultrasound plaque characteristics (GSM, DWAs and black areas) represent histopathologic markers associated with plaque vulnerability. ClinicalTrials.gov identifier: NCT02476396.

The sulci of the inferior surface of the temporal lobe: An anatomical study.

Understanding the anatomy of temporal lobe sulci and their variations can allow for safer neurosurgical approaches. Although the inferior temporal sulci and their relations to each other has been described by several authors, the nomenclature used has not been universal. The aim of this study was to investigate the anatomic features of the three main sulci of the inferior temporal lobe and provide a simple description of complex patterns among these sulci. Sulcal variations and their relations were examined in seventy formalin-fixed, adult cadaveric cerebral hemispheres. We recommend a simple but modified classification specifically for anatomic variations of the rhinal and collateral sulci. Furthermore, we describe the frequency of occipitotemporal sulci that contain 5 and 6 segments, not previously mentioned. The length and depth of all sulci were measured in all samples. Additionally, more detailed results regarding the patterns, courses, connections, relationships and measurements were given. Understanding of the complex anatomy of this clinically important region is of benefit to neurosurgeons, providing necessary guidance for neurosurgical approaches to the inferior surface of the temporal lobe. Clin. Anat. 29:932-942, 2016. © 2016 Wiley Periodicals, Inc.