Publications by authors named "Dirk Keene"

A 52-year-old woman presented with decreased vision, diplopia, esotropia, proptosis, and right orbital pain. Clinical examination was suspicious for an orbital mass and additionally revealed a thyroid gland mass. Imaging studies showed an enhancing mass within the right lateral rectus muscle and a heterogeneous mass in the left lobe of the thyroid gland.

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Several lines of evidence support immune response in brain as a mechanism of injury in Alzheimer disease (AD). Moreover, immune activation is heightened in apolipoprotein E (APOE) ε4 carriers; inhibitors of prostaglandin (PG) synthesis show a partially protective effect on AD risk from APOE ε4; and genetic variants in triggering receptor expressed on myeloid cells 2 (TREM2) are a rare but potent risk for AD. We tested the hypothesis that APOE ε4 inheritance modulates both the PGE2 pathway and TREM2 expression using primary murine microglia from targeted replacement (TR) APOE3/3 and APOE4/4 mice.

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Recent studies underline the potential relevance of microglial innate immune activation in Alzheimer disease. Primary mouse microglia that lack prostaglandin E2 receptor subtype 2 (EP2) show decreased innate immune-mediated neurotoxicity and increased amyloid β (Aβ) peptide phagocytosis, features that were replicated in vivo. Here, we tested the hypothesis that scavenger receptor CD36 is an effector of EP2-regulated Aβ phagocytosis.

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A 26-year-old patient with recurrent choriocarcinoma of the testis presented with headache and progressive left homonymous hemianopsia. On initial MRI a grade 4 arteriovenous malformation (AVM) was identified in the right occipital lobe, which was further characterized by catheter angiography. Continued worsening of the headache in the following days prompted a follow-up MRI, which revealed a new T2 hypointense nodule and adjacent vasogenic edema in the periphery of the AVM.

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A 26-year-old patient with recurrent choriocarcinoma of the testis presented with headache and progressive left homonymous hemianopsia. On initial MRI a grade 4 arteriovenous malformation (AVM) was identified in the right occipital lobe, which was further characterized by catheter angiography. Continued worsening of the headache in the following days prompted a follow-up MRI, which revealed a new T2 hypointense nodule and adjacent vasogenic edema in the periphery of the AVM.

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Introduction: Autoimmune lymphocytic hypophysitis associates predominantly with other autoimmune endocrinopathies and is most commonly treated with glucocorticoids and/or decompressive pituitary surgery. Here we report a new association and treatment modality for lymphocytic hypophysitis.

Methods: A 52-year-old woman presented with scleritis, uveitis, facial palsy, and central diabetes insipidus, accompanied by thickened pituitary stalk and enlarged pituitary on cranial MRI.

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Frontotemporal dementia (FTD) is a neurodegenerative disease with devastating changes in behavioral performance and social function. Mutations in the progranulin gene (GRN) are one of the most common causes of inherited FTD due to reduced progranulin expression or activity, including in brain where it is expressed primarily by neurons and microglia. Thus, efforts aimed at enhancing progranulin levels might be a promising therapeutic strategy.

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Apolipoprotein E (apoE) is well known as a regulator of cholesterol homeostasis, and is increasingly recognized to play a prominent role in the modulation of innate immune response, including cell-to-cell communication and migration. Alzheimer's disease (AD) is a slowly progressive neurodegenerative disorder characterized by neuroinflammation that appears to be an important component of the pathophysiology of the disease. Astrocytes are the majority cell type in brain, exerting significant influence over a range of central nervous system activities, including microglial-mediated neuroinflammatory responses.

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Synaptic dysfunction is thought to have an important role in the pathophysiology of neurodegenerative diseases, such as Alzheimer's disease (AD) and Lewy body disease (LBD). To improve our understanding of synaptic alterations in health and disease, we investigated synaptosomes prepared from post-mortem human cerebral cortex, putamen (PT), and two regions of the caudate nucleus, dorso-lateral (DL) and ventro-medial (VM), regions commonly affected in AD and LBD. We observed that the fraction of synaptosomal particles with reactivity for dopamine transporter (DAT) was significantly reduced in the PT and VM caudate of patients with neuropathological diagnosis of LBD.

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Background: Dementia is a common feature in both Huntington's disease (HD) and Alzheimer's disease (AD), as well as in the general elderly population. Few studies have examined elderly HD patients with dementia for neuropathologic evidence of both HD and AD.

Objective: We present neuropathological findings in a retrospective case series of 15 elderly HD patients (ages 60-91 years), 11 of whom had prominent clinical dementia.

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An important pathologic hallmark of Alzheimer's disease (AD) is neuroinflammation, a process characterized in AD by disproportionate activation of cells (microglia and astrocytes, primarily) of the non-specific innate immune system within the CNS. While inflammation itself is not intrinsically detrimental, a delicate balance of pro- and anti-inflammatory signals must be maintained to ensure that long-term exaggerated responses do not damage the brain over time. Non-steroidal anti-inflammatory drugs (NSAIDs) represent a broad class of powerful therapeutics that temper inflammation by inhibiting cyclooxygenase-mediated signaling pathways including prostaglandins, which are the principal mediators of CNS neuroinflammation.

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Orbital neoplasms in adults may be categorized on the basis of location and histologic type. Imaging features of these lesions often reflect their tissue composition. Cavernous malformations (also known as cavernous hemangiomas), although not true neoplasms, are the most common benign adult orbital tumor.

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Article Synopsis
  • Ataxia telangiectasia (AT) and ataxia oculomotor apraxia type 2 (AOA2) are genetic disorders related to DNA integrity, with AT leading to a significantly shortened lifespan due to cancer risks, while AOA2 has a more uncertain prognosis.
  • A case study highlights a woman with variant AT who lived to 48 with pancreatic cancer, suggesting her unique mutations may contribute to a longer-than-expected life and an unusual cancer type for AT.
  • Two siblings with AOA2, carrying novel mutations, lived into their 70s, indicating that while AOA2 can cause severe motor issues, it may also allow for a much longer lifespan compared to AT.
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A 16-year-old girl with worsening vision, new OD visual field deficits, and tumor in right orbital apex underwent biopsy and surgical excision. Orbital imaging revealed an apical tumor causing bony erosion. Histopathology confirmed the diagnosis of nodular fasciitis.

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The human apolipoprotein E (APOE) gene plays an important role in lipid metabolism. It has three common genetic variants, alleles ε2/ε3/ε4, which translate into three protein isoforms of apoE2, E3 and E4. These isoforms can differentially influence total serum cholesterol levels; therefore, APOE has been linked with cardiovascular disease.

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Apolipoprotein E4 (APOE4) genotype is the strongest genetic risk factor for late-onset Alzheimer disease and confers a proinflammatory, neurotoxic phenotype to microglia. Here, we tested the hypothesis that bone marrow cell APOE genotype modulates pathological progression in experimental Alzheimer disease. We performed bone marrow transplants (BMT) from green fluorescent protein-expressing human APOE3/3 or APOE4/4 donor mice into lethally irradiated 5-month-old APPswe/PS1ΔE9 mice.

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Alzheimer's disease (AD) is an age-related condition characterized by accumulation of neurotoxic amyloid β peptides (Aβ) in brain and retina. Because bone marrow transplantation (BMT) results in decreased cerebral Aβ in experimental AD, we hypothesized that BMT would mitigate retinal neurotoxicity through decreased retinal Aβ. To test this, we performed BMT in APPswe/PS1ΔE9 double transgenic mice using green fluorescent protein expressing wild type (wt) mice as marrow donors.

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Myeloablative (MyA) bone marrow transplantation (BMT) results in robust engraftment of BMT-derived cells in the central nervous system (CNS) and is neuroprotective in diverse experimental models of neurodegenerative diseases of the brain and retina. However, MyA irradiation is associated with significant morbidity and mortality and does not represent a viable therapeutic option for the elderly. Non-myeloablative (NMyA) BMT is less toxic, but it is not known if the therapeutic efficacy observed with MyA BMT is preserved.

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Background: The objective of this study was to report a diagnostic dilemma in a patient with multifocal choroiditis. This is a case report study.

Findings: A 68-year-old female presented with new onset of floaters in both eyes and diagnosed with bilateral panuveitis.

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Alzheimer's disease (AD) neuropathology is characterized by innate immune activation primarily through prostaglandin E2 (PGE2) signaling. Dedicator of cytokinesis 2 (DOCK2) is a guanyl nucleotide exchange factor expressed exclusively in microglia in the brain and is regulated by PGE2 receptor EP2. DOCK2 modulates microglia cytokine secretion, phagocytosis, and paracrine neurotoxicity.

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Cannabinoid receptor 1 (CB(1) receptor) controls several neuronal functions, including neurotransmitter release, synaptic plasticity, gene expression and neuronal viability. Downregulation of CB(1) expression in the basal ganglia of patients with Huntington's disease (HD) and animal models represents one of the earliest molecular events induced by mutant huntingtin (mHtt). This early disruption of neuronal CB(1) signaling is thought to contribute to HD symptoms and neurodegeneration.

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The mitogenic and second-messenger signals that promote cell proliferation often proceed through multienzyme complexes. The kinase-anchoring protein Gravin integrates cAMP and calcium/phospholipid signals at the plasma membrane by sequestering protein kinases A and C with G protein-coupled receptors. In this report we define a role for Gravin as a temporal organizer of phosphorylation-dependent protein-protein interactions during mitosis.

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Pulmonary veno-occlusive disease is a rare condition with limited treatment options. The pathological hallmark of the disease is occlusion of pulmonary venules and small veins in the lobular septa. The etiology of the disease remains obscure.

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