Ligand-dependent activation of the hedgehog pathway in glioma progenitor cells.

The hedgehog (Hh) signaling pathway regulates progenitor cells during embryogenesis and tumorigenesis in multiple organ systems. We have investigated the activity of this pathway in adult gliomas, and demonstrate that the Hh pathway is operational and activated within grade II and III gliomas, but not grade IV de novo glioblastoma multiforme. Furthermore, our studies reveal that pathway activity and responsiveness is confined to progenitor cells within these tumors. Additionally, we demonstrate that Hh signaling in glioma progenitor cells is ligand-dependent and provide evidence documenting the in vivo source of Sonic hedgehog protein. These findings suggest a regulatory role for the Hh pathway in progenitor cells within grade II and III gliomas, and the potential clinical utility of monitoring and targeting this pathway in these primary brain tumors.

Oculopharyngeal muscular dystrophy in Hispanic New Mexicans.

CONTEXT: Oculopharyngeal muscular dystrophy (OPMD) is a rare myopathy caused by polyalanine triplet repeat expansion in the gene for poly(A) binding protein 2 (PABP2) and is found in isolated cohorts throughout the world. We have observed numerous cases of OPMD in New Mexico. OBJECTIVE: To characterize the clinical, genetic, and demographic features of the OPMD population in New Mexico. DESIGN, SETTING, AND PARTICIPANTS: Cohort study with analysis of outpatient clinic medical records from 1965 to 2001 at the University of New Mexico Hospital and the New Mexico VA Health Care System in Albuquerque, which serve the entire state. MAIN OUTCOME MEASURES: Clinical phenotype, supplemented with genetic confirmation (n = 10 patients) and in-depth clinical evaluations (n = 49 patients). RESULTS: We identified 216 cases of OPMD (99 women and 117 men) from 39 kindreds of New Mexicans spanning up to 4 generations. All patients were Hispanic, and the majority of probands came from northern New Mexico. In patients who had both ocular and pharyngeal muscle weakness, ptosis was just as likely to occur before or concurrent with dysphagia. Proximal limb muscle weakness and gait abnormalities were common and occurred later than ocular or pharyngeal weakness. The clinical expression of OPMD caused marked debility, although life-table analysis showed no decrease in life expectancy compared with unaffected family members (P =.81). Ten individuals from different kindreds were found to have an identical polyalanine triplet repeat expansion ([GCG](9)) in the PABP2 gene. CONCLUSIONS: Individuals in this cohort had clinical and genetic characteristics of classic OPMD. Longevity was not affected, but patients experienced considerable morbidity. The origin of the PABP2 mutation in New Mexican OPMD patients is unclear, although the geographic and genetic isolation of northern New Mexicans with a long ancestry in this region may have contributed to the development of this cohort. This disease cohort represents a large and previously unrecognized health care issue in the state of New Mexico and should serve to raise the awareness of this disorder among clinicians who treat Hispanics in the Southwest and throughout the United States.

Sudden death due to primary diffuse leptomeningeal gliomatosis.

Tumors of the central nervous system are an unusual cause of sudden death. This report describes the sudden death of a presumed healthy 28-year-old woman from primary diffuse leptomeningeal gliomatosis. She presented to an emergency room with headache and vomiting, subsequently became unresponsive and was pronounced dead 14 h later. Autopsy revealed a diffuse extensive infiltrate of well-differentiated astrocytoma in the leptomeninges of the brain and spinal cord without an underlying parenchymal tumor. Primary diffuse leptomeningeal gliomatosis is a rare tumor that arises within the leptomeninges from small neuroglial heterotopic rests that undergo neoplastic transformation. Grossly. this tumor can mimic leptomeningeal carcinomatosis, pachymeningitis, tuberculosis, sarcoidosis, and fungal infections. However, the histologic features of primary diffuse leptomeningeal gliomatosis should allow it to be readily distinguished from grossly similar conditions. The mechanism of death in this case is most likely tumor obstruction of cerebrospinal fluid outflow resulting in the usual complications seen with increased intracranial pressure. Although this tumor is aggressive and is associated with a rapidly progressive fatal course, it has not been previously associated with sudden death.

Intranuclear inclusions in oculopharyngeal muscular dystrophy contain poly(A) binding protein 2.

Intranuclear inclusions are one of the ultrastructural hallmarks of oculopharyngeal muscular dystrophy (OPMD), a disorder caused by small polyalanine (GCG) expansions in the gene that codes for a ubiquitous nuclear protein called poly(A) binding protein 2 (PABP2). We studied OPMD skeletal muscle and found that 1.0 to 10.0% of myocyte nuclei contained discreet PABP2 immunoreactive intranuclear inclusions, providing the first direct evidence of the relation between the proposed gene for OPMD and the pathology of OPMD.

Transglutaminase aggregates huntingtin into nonamyloidogenic polymers, and its enzymatic activity increases in Huntington's disease brain nuclei.

The protein huntingtin (htt), aggregated in neuronal nuclear inclusions, is pathognomonic of Huntington's disease (HD). Constructs, translated in vitro from the N terminus of htt, containing either polyQ23 from a normal individual, or polyQ41 or polyQ67 from an HD patient, were all soluble. Transglutaminase (TGase) crosslinked these proteins, and the aggregations did not have the staining properties of amyloid. More TGase-catalyzed aggregates formed when the polyglutamine domain of htt exceeded the pathologic threshold of polyQ36. Furthermore, shorter htt constructs, containing 135 aa or fewer, formed more aggregates than did larger htt constructs. TGase activity in the HD brain was increased compared with the control, with notable increases in cell nuclei. The increased TGase activity was brain specific. In lymphoblastoid cells from HD patients, TGase activity was decreased. TGase-mediated crosslinking of htt may be involved in the formation of the nonamyloidogenic nuclear inclusions found in the HD brain. The staining properties of nuclear inclusions in the HD brain revealed that they were not amyloid.

Kearns-Sayre syndrome with features of Pearson's marrow-pancreas syndrome and a novel 2905-base pair mitochondrial DNA deletion.

Kearns-Sayre syndrome (KSS) and Pearson's marrow-pancreas syndrome (PMPS) are rare disorders caused by the same molecular defect, one of several deletion mutations in mitochondrial DNA (mtDNA). KSS is an encephalomyopathy with ophthalmoplegia, retinal degeneration, ataxia, and endocrine abnormalities. PMPS is a disorder of childhood characterized by refractory anemia, vacuolization of bone marrow cells, and exocrine pancreas dysfunction. Children with PMPS that have a mild phenotype, or are supported through bone marrow failure, often develop the encephalomyopathic features of KSS. The subject of numerous reports in the neuromuscular, genetic, and pediatric literature in recent years, very few cases of either disorder have ever been studied at autopsy. We report the results of our studies of a patient with clinically documented KSS who presented with renal dysfunction and was found to have a novel mtDNA deletion and degenerative changes in the central nervous system, retina, skeletal muscle, and pancreas.

Intranuclear inclusions and neuritic aggregates in transgenic mice expressing a mutant N-terminal fragment of huntingtin.

Huntington's disease (HD) is an inherited, neurodegenerative disorder caused by the expansion of a glutamine repeat in the N-terminus of the huntingtin protein. To gain insight into the pathogenesis of HD, we generated transgenic mice that express a cDNA encoding an N-terminal fragment (171 amino acids) of huntingtin with 82, 44 or 18 glutamines. Mice expressing relatively low steady-state levels of N171 huntingtin with 82 glutamine repeats (N171-82Q) develop behavioral abnormalities, including loss of coordination, tremors, hypokinesis and abnormal gait, before dying prematurely. In mice exhibiting these abnormalities, diffuse nuclear labeling, intranuclear inclusions and neuritic aggregates, all immunoreactive with an antibody to the N-terminus (amino acids 1-17) of huntingtin (AP194), were found in multiple populations of neurons. None of these behavioral or pathological phenotypes were seen in mice expressing N171-18Q. These findings are consistent with the idea that N-terminal fragments of huntingtin with a repeat expansion are toxic to neurons, and that N-terminal fragments are prone to form both intranuclear inclusions and neuritic aggregates.

Axonal transport of mutant superoxide dismutase 1 and focal axonal abnormalities in the proximal axons of transgenic mice.

Superoxide dismutase 1 (SOD1), a ubiquitously expressed enzyme, detoxifies superoxide radicals and participates in copper homeostasis. Mutations in this enzyme have been linked to a subset of autosomal dominant cases of familial amyotrophic lateral sclerosis (FALS), a disorder characterized by selective degeneration of motor neurons. Transgenic mice expressing FALS mutant human (Hu) SOD1 at high levels develop a motor neuron disease, indicating that mutant Hu SOD1 gains properties that are particularly toxic to motor neurons. In this report, we demonstrate that transgenic mice expressing Hu SOD1 with the G37R FALS mutation, but not mice expressing wild-type enzyme, develop focal increases in immunoreactivity in the proximal axons of spinal motor neurons. This SOD1 immunoreactivity and immunoreactivity to hypophosphorylated neurofilament H epitopes are found adjacent to small vacuoles in axons. Using metabolic radiolabeling methods, we show that mutant G37R HuSOD1 as well as endogenous mouse SOD1 are transported anterograde in slow component b in motor and sensory axons of the sciatic nerve. Together, these findings suggest that anterogradely transported mutant SOD1 may act locally to damage motor axons.

Patients with features similar to Huntington's disease, without CAG expansion in huntingtin.

OBJECTIVE: To describe characteristics of gene-negative patients with clinical features of Huntington's disease (HD), exploring likely etiologies. BACKGROUND: When a direct gene test became definitive for diagnosis of HD, we discovered a number of patients in our clinics in Baltimore, MD, and Cambridge, UK, believed or suspected to have HD who did not have the triplet repeat expansion. METHODS: Patients were examined using standardized instruments, and given full neurologic and psychiatric evaluations. Those negative for HD were tested for dentatorubro-pallidoluysian atrophy, SCA-1, SCA-3, SCA-2, SCA-6, and other conditions as indicated. RESULTS: Of 15 patients, 7 received specific diagnoses or appear to be sporadic cases, 4 have a possible but uncertain relation to HD, and 4 have unknown familial progressive movement disorders. CONCLUSIONS: This last group of patients might be properly described as phenocopies of HD, some of which may be caused by unidentified triplet repeat expansions.

Intranuclear neuronal inclusions in Huntington's disease and dentatorubral and pallidoluysian atrophy: correlation between the density of inclusions and IT15 CAG triplet repeat length.

Huntington's disease (HD) is caused by CAG triplet repeat expansion in IT15 which leads to polyglutamine stretches in the HD protein product, huntingtin. The pathological hallmark of HD is the degeneration of subsets of neurons, primarily those in the striatum and neocortex. Specific morphological markers of affected cells have not been identified in patients with HD, although a unique itranuclear inclusion was recently reported in neurons of transgenic animals expressing a construct encoding the N-terminal part (including the glutamine repeat) of huntingtin (Davies et al., 1997). In order to understand the importance of this finding, we sought for comparable nuclear abnormalities in autopsy material from patients with HD. In all 20 HD cases examined, anti-ubiquitin and N-terminal huntingtin antibodies identified itranuclear inclusions in neurons and the frequency of these lesions correlated with the length of the CAG repeat in IT15. In addition, examination of material from the related HD-like triplet repeat disorder, dentatorubral and pallidoluysian atrophy, also revealed intranuclear neuronal inclusions. These findings suggest that intranuclear inclusions containing protein aggregates may be common feature of the pathogenesis of glutamine repeat neurodegenerative disorders.

Overexpression of human copper, zinc-superoxide dismutase (SOD1) prevents postischemic injury.

Superoxide and superoxide-derived oxidants have been hypothesized to be important mediators of postischemic injury. Whereas copper, zinc-superoxide dismutase, SOD1, efficiently dismutates superoxide, there has been controversy regarding whether increasing intracellular SOD1 expression would protect against or potentiate cellular injury. To determine whether increased SOD1 protects the heart from ischemia and reperfusion, studies were performed in a newly developed transgenic mouse model in which direct measurement of superoxide, contractile function, bioenergetics, and cell death could be performed. Transgenic mice with overexpression of human SOD1 were studied along with matched nontransgenic controls. Immunoblotting and immunohistology demonstrated that total SOD1 expression was increased 10-fold in hearts from transgenic mice compared with nontransgenic controls, with increased expression in both myocytes and endothelial cells. In nontransgenic hearts following 30 min of global ischemia a reperfusion-associated burst of superoxide generation was demonstrated by electron paramagnetic resonance spin trapping. However, in the transgenic hearts with overexpression of SOD1 the burst of superoxide generation was almost totally quenched, and this was accompanied by a 2-fold increase in the recovery of contractile function, a 2.2-fold decrease in infarct size, and a greatly improved recovery of high energy phosphates compared with that in nontransgenic controls. These results demonstrate that superoxide is an important mediator of postischemic injury and that increasing intracellular SOD1 dramatically protects the heart from this injury. Thus, increasing intracellular SOD1 expression may be a highly effective approach to decrease the cellular injury that occurs following reperfusion of ischemic tissues.

AIDS-related MR hyperintensity of the basal ganglia.

PURPOSE: Our goal was to describe the MR imaging appearance and clinical pathologic correlates of bilateral basal ganglia hyperintensity in acquired immunodeficiency syndrome (AIDS). METHODS: Medical records and laboratory data were reviewed retrospectively in nine cases of bilateral basal ganglia hyperintensity on long-repetition-time MR images. Opportunistic infections of the central nervous system were excluded by clinical and laboratory data. Postmortem neuropathologic examination was obtained in two cases. RESULTS: All patients presented acutely with new seizures or changes in mental status. A history of drug abuse was elicited in seven of the nine remaining patients. Renal failure was present in six cases. Symmetric bilateral caudate and putamen hyperintensity on T2-weighted images was found in all cases with variable extension to the surrounding white matter, thalamus, and brain stem. Postmortem neuropathologic examination in two cases revealed numerous microinfarcts in a distribution similar to the MR signal abnormalities. CONCLUSION: The MR appearance of basal ganglia hyperintensity in this series of AIDS patients represents ischemic tissue injury. We propose that this clinicopathologic entity is precipitated by the combined effects of human immunodeficiency virus infection and drug use, particularly cocaine and/or associated toxic contaminants.

Pathogenesis of neurodegenerative diseases associated with expanded glutamine repeats: new answers, new questions.

Eight diseases are now known to be caused by an expansion mutation of the trinucleotide repeat CAG encoding glutamine. Each disease is caused by a CAG expansion in a different gene, and the genes bear no similarity to each other except for the presence of the repeat. Nonetheless, the essential feature of all of these disorders is neurodegeneration in a set of overlapping cortical and subcortical regions. Disease age of onset, and in some cases severity, is correlated with repeat length. These and other observations have led to the hypothesis that CAG expansion causes disease by a toxic gain-of-function of the encoded stretch of polyglutamine residues. Expansion-induced abnormalities of cytoskeletal function or neuronal signalling processes may contribute to the pathogenic process. In addition, theoretical and experimental analysis of the chemistry of uninterrupted stretches of glutamine residues suggest that polyglutamine-containing proteins or protein fragments may aggregate, via a "polar zipper", into beta pleated sheets. Recent findings have now established the presence of such aggregates in selected regions of brain from affected individuals, in transgenic mice expressing expanded repeats, and in isolated cells transfected with expanded repeats. The aggregates are most prominently manifest as neuronal intranuclear inclusion bodies. As the investigation of the link between these inclusions and cell dysfunction and death continues, it is possible that new avenues for therapeutic intervention will emerge.

Brain capillary telangiectasia: MR imaging appearance and clinicohistopathologic findings.

PURPOSE: To demonstrate the clinical and magnetic resonance (MR) imaging findings of brain capillary telangiectasia and compare them with postmortem specimens. MATERIALS AND METHODS: MR images obtained in and clinical histories of 18 adult patients with a presumed diagnosis of capillary telangiectasia examined within 3 years were retrospectively reviewed. All patients had undergone MR imaging with conventional T1- and T2-weighted spin-echo sequences and gadolinium-enhanced T1-weighted and susceptibility-sensitive gradient-echo (GRE) sequences. No biopsies had been performed. Fourteen patients had undergone clinical and MR imaging follow-up (median, 11 months). Postmortem tissues from three cases of histopathologically confirmed capillary telangiectasia were imaged. RESULTS: All lesions were small, homogeneously enhancing, and hypo- to isointense on T1-weighted images and iso- to slightly hyperintense on proton-density- and T2-weighted images. None was hypointense on proton-density- or T2-weighted images. All lesions showed marked GRE signal loss. None had changed at follow-up. Two patients had multiple classic cerebral cavernous angiomas. The three specimens showed no abnormal susceptibility and contained no hemosiderin at tissue analysis. CONCLUSION: Capillary telangiectasia has mild contrast material enhancement but is otherwise undetectable on conventional MR images. It lacks the "hemosiderin rim" of cavernous angioma and demonstrates increased susceptibility only on GRE images, likely owing to blood oxygen-level-dependent contrast. GRE is essential in diagnosing brain capillary telangiectasia, which could otherwise be misdiagnosed as neoplasia, subacute infarction, or demyelination.

Huntington's disease and dentatorubral-pallidoluysian atrophy: proteins, pathogenesis and pathology.

Each of the glutamine repeat neurodegenerative diseases has a particular pattern of pathology largely restricted to the CNS. However, there is considerable overlap among the regions affected, suggesting that the diseases share pathogenic mechanisms, presumably involving the glutamine repeats. We focus on Huntington's disease (HD) and Dentatorubral-pallidoluysian atrophy (DRPLA) as models for this family of diseases, since they have striking similarities and also notable differences in their clinical features and pathology. We review the pattern of pathology in adult and juvenile onset cases. Despite selective pathology, the disease genes and their protein products (huntingtin and atrophin-1) are widely expressed. This presents a central problem for all the glutamine repeat diseases-how do widely expressed gene products give rise to restricted pathology? The pathogenic effects are believed to occur via a "gain of function" mechanism at the protein level. Mechanisms of cell death may include excitotoxicity, metabolic toxicity, apoptosis, and free radical stress. Emerging data indicate that huntingtin and atrophin-1 may have distinct protein interactions. The specific interaction partners may help explain the selective pathology of these diseases.

Elevated free nitrotyrosine levels, but not protein-bound nitrotyrosine or hydroxyl radicals, throughout amyotrophic lateral sclerosis (ALS)-like disease implicate tyrosine nitration as an aberrant in vivo property of one familial ALS-linked superoxide dismutase 1 mutant.

Mutations in superoxide dismutase 1 (SOD1; EC 1.15.1.1) are responsible for a proportion of familial amyotrophic lateral sclerosis (ALS) through acquisition of an as-yet-unidentified toxic property or properties. Two proposed possibilities are that toxicity may arise from imperfectly folded mutant SOD1 catalyzing the nitration of tyrosines [Beckman, J. S., Carson, M., Smith, C. D. & Koppenol, W. H. (1993) Nature (London) 364, 584] through use of peroxynitrite or from peroxidation arising from elevated production of hydroxyl radicals through use of hydrogen peroxide as a substrate [Wiedau-Pazos, M., Goto, J. J., Rabizadeh, S., Gralla, E. D., Roe, J. A., Valentine, J. S. & Bredesen, D. E. (1996) Science 271, 515-518]. To test these possibilities, levels of nitrotyrosine and markers for hydroxyl radical formation were measured in two lines of transgenic mice that develop progressive motor neuron disease from expressing human familial ALS-linked SOD1 mutation G37R. Relative to normal mice or mice expressing high levels of wild-type human SOD1, 3-nitrotyrosine levels were elevated by 2- to 3-fold in spinal cords coincident with the earliest pathological abnormalities and remained elevated in spinal cord throughout progression of disease. However, no increases in protein-bound nitrotyrosine were found during any stage of SOD1-mutant-mediated disease in mice or at end stage of sporadic or SOD1-mediated familial human ALS. When salicylate trapping of hydroxyl radicals and measurement of levels of malondialdehyde were used, there was no evidence throughout disease progression in mice for enhanced production of hydroxyl radicals or lipid peroxidation, respectively. The presence of elevated nitrotyrosine levels beginning at the earliest stages of cellular pathology and continuing throughout progression of disease demonstrates that tyrosine nitration is one in vivo aberrant property of this ALS-linked SOD1 mutant.

Dentatorubral and pallidoluysian atrophy (DRPLA). Clinical and neuropathological findings in genetically confirmed North American and European pedigrees.

Dentatorubral and pallidoluysian atrophy (DRPLA) is an autosomal dominant disorder that clinically overlaps with Huntington's disease (HD) and manifests combinations of chorea, myoclonus, seizures, ataxia, and dementia. DRPLA is caused by a CAG triplet repeat (CTG-B37) expansion coding for polyglutamine on chromosome 12 and exhibits the genetic phenomenon of anticipation. This neurodegenerative disease has only rarely been reported in non-Japanese pedigrees, and there are only a few neuropathological studies in genetically confirmed patients. We report 10 cases of DRPLA from two North American and two British pedigrees in which CTG-B37 expansions have been demonstrated within each kindred (54-83 repeats), individually in 8 of the 10 cases, and describe the neuropathological findings in 4 cases. Members of DRPLA kindreds have a wide range of clinical phenotypes and markedly variable ages at onset. The neuropathological spectrum is centered around the cerebellifugal and pallidofugal systems, but neurodegenerative changes can be found in many nuclei, tracts, and systems. Evidence of CTG-B37 triplet repeat expansion should be sought in HD-like cases that are negative for expanded triplet repeats within the HD IT15 gene or in autopsy cases with degeneration of the dentatorubral or pallidoluysian systems.