Progressive myopathy in an inducible mouse model of oculopharyngeal muscular dystrophy.

The genetic basis of oculopharyngeal muscular dystrophy (OPMD) is a short expansion of a polyalanine tract (normal allele: 10 alanines, mutant allele: 11-17 alanines) in the nuclear polyadenylate binding protein PABPN1 which is essential for controlling poly(A) tail length in messenger RNA. Mutant PABPN1 forms nuclear inclusions in OPMD muscle. To investigate the pathogenic role of mutant PABPN1 in vivo, we generated a ligand-inducible transgenic mouse model by using the mifepristone-inducible gene expression system. Induction of ubiquitous expression of mutant PABPN1 resulted in skeletal and cardiac myopathy. Histological changes of degenerative myopathy were preceded by nuclear inclusions of insoluble PABPN1. Downregulation of mutant PABPN1 expression attenuated the myopathy and reduced the nuclear burden of insoluble PABPN1. These results support association between mutant PABPN1 accumulation and degenerative myopathy in mice. Resolution of myopathy in mice suggests that the disease process in OPMD patients may be treatable.

Practical neuropathology synoptic reporting for central nervous system tumors.

CONTEXT: Synoptic reporting for central nervous system (CNS) tumors has never been formally addressed, and neuropathologists lack practical templates that they can adapt to their laboratory information system to be compliant with College of American Pathologists (CAP) standards. OBJECTIVES: To provide practical synoptic report templates designed for CNS tumors that allow for easy data extraction and CAP compliance and improve the reporting of CNS tumors. DATA SOURCES: Review of literature and synoptic report format experience in our practice. CONCLUSIONS: Synoptic reporting of required elements is a recently introduced standard for CNS tumors. It is difficult to use a universal non-CNS tumor synoptic report template for CNS tumors because they are heavily weighted to include items not important or required for CNS tumors, such as margins and the TNM classification system. In addition, the CAP CNS protocol, published in 2008, is an immense comprehensive document that is not conducive to simple inclusion in a narrative report. We describe our experience using a synoptic template for CNS tumors that includes all required elements, is tailored to the practice of neuropathology, and can easily be adapted to other laboratory information systems. Because of the multidisciplinary nature of CNS tumor diagnoses, neuropathologists typically collect clinical, demographic, and imaging data on all CNS tumor cases. These data can readily be entered into a primary synoptic report that could replace our standard narrative report.

Immunohistochemical analysis of metastatic neoplasms of the central nervous system.

Metastatic neoplasms to the central nervous system are often encountered in the practice of surgical neuropathology. It is not uncommon for patients with systemic malignancies to present to medical attention because of symptoms from a brain metastasis and for the tissue samples procured from these lesions to represent the first tissue available to study a malignancy from an unknown primary. In general surgical pathology, the evaluation of a metastatic neoplasm of unknown primary is a very complicated process, requiring knowledge of numerous different tumor types, reagents, and staining patterns. The past few years, however, have seen a remarkable refinement in the immunohistochemical tools at our disposal that now empower neuropathologists to take an active role in defining the relatively limited subset of neoplasms that commonly metastasize to the central nervous system. This information can direct imaging studies to find the primary tumor in a patient with an unknown primary, clarify the likely primary site of origin in patients who have small tumors in multiple sites without an obvious primary lesion, or establish lesions as late metastases of remote malignancies. Furthermore, specific treatments can begin and additional invasive procedures may be prevented if the neuropathologic evaluation of metastatic neoplasms provides information beyond the traditional diagnosis of "metastatic neoplasm." In this review, differential cytokeratins, adjuvant markers, and organ-specific antibodies are described and the immunohistochemical signatures of metastatic neoplasms that are commonly seen by neuropathologists are discussed.

Cytomegalovirus ventriculoencephalitis in a peripheral blood stem cell transplant recipient.

Cytomegalovirus encephalitis occurs rarely in transplant recipients. We describe a patient with cytomegalovirus ventriculoencephalitis who had a very high CSF viral load but a low peripheral blood viral load. No resistance mutations were present in cerebrospinal fluid viral DNA, whereas DNA from blood showed a resistance mutation in the UL54 gene but not in the UL97 gene. Viral replication was intense in the brain ependyma and periventricular areas without evidence of peripheral cytomegalovirus disease. The data provide evidence for compartmentalization of cytomegalovirus infection. Levels of ganciclovir and foscarnet in the cerebrospinal fluid may be inadequate for treatment, even for some drug-susceptible strains, and, together with periventricular replication, may explain the disparity between cerebrospinal fluid viral load and peripheral blood viral load.

Prolonged survival and decreased abnormal movements in transgenic model of Huntington disease, with administration of the transglutaminase inhibitor cystamine.

An expanded polyglutamine domain in huntingtin underlies the pathogenic events in Huntington disease (HD), characterized by chorea, dementia and severe weight loss, culminating in death. Transglutaminase (TGase) may be critical in the pathogenesis, via cross-linking huntingtin. Administration of the TGase competitive inhibitor, cystamine, to transgenic mice expressing exon 1 of huntingtin containing an expanded polyglutamine repeat, altered the course of their HD-like disease. Cystamine given intraperitoneally entered brain where it inhibited TGase activity. When treatment began after the appearance of abnormal movements, cystamine extended survival, reduced associated tremor and abnormal movements and ameliorated weight loss. Treatment did not influence the appearance or frequency of neuronal nuclear inclusions. Unexpectedly, cystamine treatment increased transcription of one of the two genes shown to be neuroprotective for polyglutamine toxicity in Drosophila, dnaj (also known as HDJ1 and Hsp40 in humans and mice, respectively). Inhibition of TGase provides a new treatment strategy for HD and other polyglutamine diseases.

July 2001: 58-year-old man with a temporal bone mass.

The July 2001 Case of the Month (COM). A 58-year-old man with right ear hearing loss since childhood presented with a two year history of dizziness and vertigo. Neuroradiological studies showed a large mass arising from the petrous portion of the temporal bone. The lesion was resected and microscopic examination revealed a cholesterol granuloma with a small component of cholesteatoma. It is important to distinguish between cholesterol granuloma and cholesteatoma because of treatment differences. However, these two entities can occasionally be seen together and rare giant variants have been described.

Evidence for a role for transglutaminase in Huntington's disease and the potential therapeutic implications.

Transglutaminase (TGase) activity is increased in affected regions of brains from patients with Huntington's disease (HD). TGase activity is particularly elevated in the nucleus compared with the cytoplasm from these brains. Gamma-glutaminyl-lysyl cross-links have been detected in nuclear inclusions in HD brain, indicating that TGase may play a prominent role in the aggregation of huntingtin (htt). Attempts to ameliorate experimental disease, via inhibition of TGase in transgenic models of HD in mice, are under investigation.

Genetic ablation of the t-SNARE SNAP-25 distinguishes mechanisms of neuroexocytosis.

Axon outgrowth during development and neurotransmitter release depends on exocytotic mechanisms, although what protein machinery is common to or differentiates these processes remains unclear. Here we show that the neural t-SNARE (target-membrane-associated-soluble N-ethylmaleimide fusion protein attachment protein (SNAP) receptor) SNAP-25 is not required for nerve growth or stimulus-independent neurotransmitter release, but is essential for evoked synaptic transmission at neuromuscular junctions and central synapses. These results demonstrate that the development of neurotransmission requires the recruitment of a specialized SNARE core complex to meet the demands of regulated exocytosis.