Mary Fowkes

AAV8-mediated gene therapy prevents induced biochemical attacks of acute intermittent porphyria and improves neuromotor function.

Acute intermittent porphyria (AIP), an autosomal dominant hepatic porphyria due to half-normal hydroxymethylbilane synthase (HMB-synthase) activity, is manifested by life-threatening acute neurological attacks that are precipitated by factors that induce heme biosynthesis. The acute attacks are currently treated with intravenous hemin, but a more continuous therapy is needed, particularly for patients experiencing frequent attacks. Thus, a recombinant AAV8-based serotype vector expressing murine HMB-synthase driven by liver-specific regulatory elements was generated and its effectiveness to prevent the biochemical induction of an acute attack was evaluated in an AIP mouse model. Intraperitoneal administration of the adeno-associated viral (AAV) vector resulted in a rapid and dose-dependent increase of HMB-synthase activity that was restricted to the liver. Stable expression of hepatic HMB-synthase was achieved and wild-type or greater levels were sustained for 36 weeks. When heme synthesis was periodically induced by a series of phenobarbital injections, the treated mice did not accumulate urinary delta-aminolevulinic acid (ALA) or porphobilinogen (PBG), indicating that the expressed enzyme was functional in vivo and prevented induction of the acute attack. Further, rotarod performance and footprint analyses improved significantly. Thus, liver-directed gene therapy provided successful long-term correction of the hepatic metabolic abnormalities and improved neuromotor function in the murine model of human AIP.

Differential gene expression in patients with amyotrophic lateral sclerosis.

Abstract Our objective was to analyze gene expression pattern in muscles from patients with amyotrophic lateral sclerosis (ALS) and multifocal motor neuropathy (MMN) compared to controls. Biopsied skeletal muscles from three ALS, three MMN and three control subjects had total RNA extracted and subjected to genome-wide gene expression analysis using Affymetrix GeneChip Exon 1.0 ST array. The most significant expression pattern differences were confirmed with RT-PCR in four additional ALS patients. Results showed that over 3000 genes were identified across the groups using q < 10%. Among 50 genes that were overexpressed only in the ALS group were: leucine-rich repeat kinase-2, follistatin, collagen type XIX alpha-1, ceramide kinase-like, sestrin-3 and CXorf64. No genes were significantly overexpressed in MMN alone. Underexpressed genes only in ALS included actinin α3, fructose-1,6-bisphosphatase-2 and homeobox C10; whereas only in MMN: hemoglobin A1 and CXorf64. Ankyrin repeat domain-1 was overexpressed in both groups. Underexpressed genes in both groups included myosin light chain kinase-2, enolase-3 and 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase-1. Validation analysis using RT-PCR confirmed the data for leucine-rich repeat kinase-2, follistatin, collagen type XIX alpha-1, ceramide kinase-like, sestrin-3 and CXorf64. In conclusion, there is differential tissue-specific gene expression in patients with ALS relative to MMN and controls. Further studies are necessary to evaluate the identified genes in larger patient groups and different tissues.

Human habenula segmentation using myelin content

The habenula consists of a pair of small epithalamic nuclei located adjacent to the dorsomedial thalamus. Despite increasing interest in imaging the habenula due to its critical role in mediating subcortical reward circuitry, in vivo neuroimaging research targeting the human habenula has been limited by its small size and low anatomical contrast. In this work, we have developed an objective semi-automated habenula segmentation scheme consisting of histogram-based thresholding, region growing, geometric constraints, and partial volume estimation steps. This segmentation scheme was designed around in vivo 3 T myelin-sensitive images, generated by taking the ratio of high-resolution T1w over T2w images. Due to the high myelin content of the habenula, the contrast-to-noise ratio with the thalamus in the in vivo 3T myelin-sensitive images was significantly higher than the T1w or T2w images alone. In addition, in vivo 7 T myelin-sensitive images (T1w over T2*w ratio images) and ex vivo proton density-weighted images, along with histological evidence from the literature, strongly corroborated the in vivo 3 T habenula myelin contrast used in the proposed segmentation scheme. The proposed segmentation scheme represents a step toward a scalable approach for objective segmentation of the habenula suitable for both morphological evaluation and habenula seed region selection in functional and diffusion MRI applications.

Primary CNS plasmablastic lymphoma: Report of a case with CSF cytology, flow cytometry, radiology, histological correlation, and review of the literature

Plasmablastic lymphoma (PBL) is a rare subtype of diffuse large B cell lymphoma and commonly presents as an oral mass in HIV patients. Extraoral PBL has been reported, including one case of primary central nervous system PBL (PCNSPBL). The cytological features of PBL have been described, including cerebrospinal fluid (CSF) cytology findings for secondary CNS involvement by PBL. The etiology of PCNSPBL is still unknown. We report here the CSF cytology of a PCNSPBL, which shows a hypercellular specimen composed of markedly atypical, singly dispersed plasmacytoid cells with frequent abnormal mitoses and binucleation. The neoplastic cells are positive for CD138. Flow cytometry of the CSF specimen demonstrates a monoclonal neoplastic cell population, which is CD138 positive, kappa light chain positive, lambda light chain negative, and CD19 negative. Molecular analysis and immunohistochemical stains on a tissue biopsy confirmed the diagnosis and reveal concurrent infections with Epstein‐Barr virus and human polyomavirus JC virus. Clinical and radiological correlations are reported, and the literature is reviewed. To the best of our knowledge, this is the first case report for CSF cytology of a PCNSPBL, demonstrating the utility of the cytological examination in the triage and diagnosis of this disease. Because of its dismal prognosis, it is critical for cytopathologists to be aware of the entity and recognize the neoplastic cells in CSF specimen. This report also emphasizes the importance of clinical and radiological correlation in the diagnosis of this lethal disease. Diagn. Cytopathol. 2011.

ACTH-producing remnants following apoplexy of an ACTH-secreting pituitary macroadenoma

Describe a case of apoplexy of an ACTH-producing pituitary adenoma which resulted not only in an empty sella with concurrent hypothyroidism, hypoprolactinemia, and hypogonadism but persistent hypercortisolemia from two distinct extrasellar remnants of the original adenoma. Review the literature to identify other similar cases. The patient’s medical history, physical exam, lab data, imaging exams and histopathological results were analyzed and compiled into a case report, and an extensive review of the literature was performed. Endocrinological data revealed hypercortisolism and an elevated ACTH with an otherwise suppressed pituitary axis. A pituitary MRI showed a macroadenoma in the left cavernous sinus in addition to an empty sella. An octreotide scan revealed lesions in the left sella turcica and the right sphenoid sinus. Tissue samples of both lesions stained positive for ACTH and negative for GH, prolactin, FSH, LH, and TSH. The lesions were surgically removed, and the patient treated with radiation and ketoconazole. This resulted in a significant decrease in ACTH and cortisol as well as a marked improvement in blood glucose control. The review of literature revealed the absence of any similar cases in the past. The patient presented with apoplexy of an ACTH-secreting pituitary macroadenoma with two hormonally active extrasellar remnants. Several cases in the literature describe recurrence of Cushing’s disease following infarction of ACTH-secreting adenomas. This is the first documented case of infarction of an ACTH-producing adenoma resulting in two distinct ACTH-producing remnants without recurrence of the original adenoma.

Prospective Isolation and Comparison of Human Germinal Matrix and Glioblastoma EGFR+ Populations with Stem Cell Properties

Summary Characterization of non-neoplastic and malignant human stem cell populations in their native state can provide new insights into gliomagenesis. Here we developed a purification strategy to directly isolate EGFR+/− populations from human germinal matrix (GM) and adult subventricular zone autopsy tissues, and from de novo glioblastoma (GBM) resections, enriching for cells capable of binding EGF ligand (LBEGFR+), and uniquely compared their functional and molecular properties. LBEGFR+ populations in both GM and GBM encompassed all sphere-forming cells and displayed proliferative stem cell properties in vitro. In xenografts, LBEGFR+ GBM cells showed robust tumor initiation and progression to high-grade, infiltrative gliomas. Whole-transcriptome sequencing analysis confirmed enrichment of proliferative pathways in both developing and neoplastic freshly isolated EGFR+ populations, and identified both unique and shared sets of genes. The ability to prospectively isolate stem cell populations using native ligand-binding capacity opens new doors onto understanding both normal human development and tumor cell biology.

Identification of a novel RASD1 somatic mutation in a USP8-mutated corticotroph adenoma

Cushings disease (CD) is caused by pituitary corticotroph adenomas that secrete excess adrenocorticotropic hormone (ACTH). In these tumors, somatic mutations in the gene USP8 have been identified as recurrent and pathogenic and are the sole known molecular driver for CD. Although other somatic mutations were reported in these studies, their contribution to the pathogenesis of CD remains unexplored. No molecular drivers have been established for a large proportion of CD cases and tumor heterogeneity has not yet been investigated using genomics methods. Also, even in USP8-mutant tumors, a possibility may exist of additional contributing mutations, following a paradigm from other neoplasm types where multiple somatic alterations contribute to neoplastic transformation. The current study utilizes whole-exome discovery sequencing on the Illumina platform, followed by targeted amplicon-validation sequencing on the Pacific Biosciences platform, to interrogate the somatic mutation landscape in a corticotroph adenoma resected from a CD patient. In this USP8-mutated tumor, we identified an interesting somatic mutation in the gene RASD1, which is a component of the corticotropin-releasing hormone receptor signaling system. This finding may provide insight into a novel mechanism involving loss of feedback control to the corticotropin-releasing hormone receptor and subsequent deregulation of ACTH production in corticotroph tumors.

BK virus encephalopathy and sclerosing vasculopathy in a patient with hypohidrotic ectodermal dysplasia and immunodeficiency

Human BK polyomavirus (BKV) is reactivated under conditions of immunosuppression leading most commonly to nephropathy or cystitis; its tropism for the brain is rare and poorly understood. We present a unique case of BKV-associated encephalopathy in a man with hypohidrotic ectodermal dysplasia and immunodeficiency (HED-ID) due to IKK-gamma (NEMO) mutation, who developed progressive neurological symptoms. Brain biopsy demonstrated polyomavirus infection of gray and white matter, with predominant involvement of cortex and distinct neuronal tropism, in addition to limited demyelination and oligodendroglial inclusions. Immunohistochemistry demonstrated polyoma T-antigen in neurons and glia, but expression of VP1 capsid protein only in glia. PCR analysis on both brain biopsy tissue and cerebrospinal fluid detected high levels of BKV DNA. Sequencing studies further identified novel BKV variant and disclosed unique rearrangements in the noncoding control region of the viral DNA (BKVN NCCR). Neuropathological analysis also demonstrated an unusual form of obliterative fibrosing vasculopathy in the subcortical white matter with abnormal lysosomal accumulations, possibly related to the patient’s underlying ectodermal dysplasia. Our report provides the first neuropathological description of HED-ID due to NEMO mutation, and expands the diversity of neurological presentations of BKV infection in brain, underscoring the importance of its consideration in immunodeficient patients with unexplained encephalopathy. We also document novel BKVN NCCR rearrangements that may be associated with the unique neuronal tropism in this patient.

High-resolution temporal and regional mapping of MAPT expression and splicing in human brain development

The microtubule associated protein tau plays a critical role in the pathogenesis of neurodegenerative disease. Recent studies suggest that tau also plays a role in disorders of neuronal connectivity, including epilepsy and post-traumatic stress disorder. Animal studies have shown that the MAPT gene, which codes for the tau protein, undergoes complex pre-mRNA alternative splicing to produce multiple isoforms during brain development. Human data, particularly on temporal and regional variation in tau splicing during development are however lacking. In this study, we present the first detailed examination of the temporal and regional sequence of MAPT alternative splicing in the developing human brain. We used a novel computational analysis of large transcriptomic datasets (total n = 502 patients), quantitative polymerase chain reaction (qPCR) and western blotting to examine tau expression and splicing in post-mortem human fetal, pediatric and adult brains. We found that MAPT exons 2 and 10 undergo abrupt shifts in expression during the perinatal period that are unique in the canonical human microtubule-associated protein family, while exon 3 showed small but significant temporal variation. Tau isoform expression may be a marker of neuronal maturation, temporally correlated with the onset of axonal growth. Immature brain regions such as the ganglionic eminence and rhombic lip had very low tau expression, but within more mature regions, there was little variation in tau expression or splicing. We thus demonstrate an abrupt, evolutionarily conserved shift in tau isoform expression during the human perinatal period that may be due to tau expression in maturing neurons. Alternative splicing of the MAPT pre-mRNA may play a vital role in normal brain development across multiple species and provides a basis for future investigations into the developmental and pathological functions of the tau protein.

Immunohistochemical Detection of Motor Endplates in the Long-Term Denervated Muscle

Background We have demonstrated that the native motor zone (NMZ) within a muscle is an ideal target for performing nerve‐muscle‐endplate band grafting (NMEG) to restore motor function of a denervated muscle. This study was designed to determine spatiotemporal alterations of the myofibers, motor endplates (MEPs), and axons in the NMZ of long‐term denervated muscles for exploring if NMEG‐NMZ technique would have the potential for delayed reinnervation. Methods Sternomastoid (SM) muscles of adult female Sprague‐Dawley rats (n = 21) were experimentally denervated and denervation‐induced changes in muscle weight, myofiber size, MEPs, and intramuscular nerve axons were evaluated histomorphometrically and immunohistochemically at the end of 3, 6, and 9 months after denervation. The values obtained from the ipsilateral normal side served as control. Results The denervated SM muscles exhibited a progressive reduction in muscle weight (38%, 31%, and 19% of the control) and fiber diameter (52%, 40%, and 28% of the control) for 3‐, 6‐, and 9‐month denervation, respectively. The denervated MEPs were still detectable even 9 months after denervation. The mean number of the denervated MEPs was 79%, 65%, and 43% of the control in the 3‐, 6‐, and 9‐month denervated SM, respectively. Degenerated axons in the denervated muscles became fragmented. Conclusions Persistence of MEPs in the long‐term denervated SM suggests that some surgeries targeting the MEPs such as NMEG‐NMZ technique should be effective for delayed reinnervation. However, more work is needed to develop strategies for preservation of muscle mass and MEPs after denervation.