A facility for cryogenic ion irradiation and in situ characterization of rare-earth barium copper oxide superconducting tapes.

Superconducting magnets based on Rare Earth Barium Copper Oxides (REBCO) offer transformative capabilities in the fields of fusion energy, high energy physics, and space exploration. A challenge shared by these applications is the limited lifetime of REBCO due to radiation damage sustained during operation. Here we present a new ion-beam facility that enables simultaneous cryogenic irradiation and in situ characterization of commercial REBCO tapes. The ion source provides spatially uniform fluxes up to 1018 protons/m2s with kinetic energies up to 3.4 MeV, in addition to helium and higher-Z species. Using this facility, we can induce uniform damage profiles in the first 10-20 µm of REBCO tapes with less than 0.25 appm of hydrogen implanted in REBCO after a dose of 1020 protons/m2. The tape can be held between 20 and 300 K with an accuracy of ±0.1 K and is connected to a four-point probe measuring the critical current, Ic, and critical temperature, Tc, before, during, and after irradiation with transport current ranging from 100 nA to 100 A, and a typical voltage noise less than 0.1 µV. These capabilities are presently used to study the effect of irradiation temperature on REBCO performance change during and after proton bombardment, to assess the possibility of Ic and Tc recovery after irradiation through thermal annealing, and to explore the instantaneous and recoverable suppression of Ic and Tc observed during irradiation.

Linkage of an important gene locus for tuberous sclerosis to a chromosome 16 marker for polycystic kidney disease.

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder of unknown aetiology that affects numerous body systems including skin, brain and kidneys. Some TSC has been linked to chromosome 9, additional TSC genes on chromosomes 11 and 12 have been proposed, but the majority of TSC families remain unlinked. Using TSC families in which data had excluded linkage to chromosome 9, we failed to detect linkage with loci on chromosomes 11, 12 and others. One marker examined was D16S283, the closest locus on the proximal side of the polycystic kidney disease type 1 (PKD1) gene. Linkage between TSC and D16S283 demonstrated a lod score of 9.50 at theta = 0.02 with one family independently presenting a lod score of 4.44 at theta = 0.05. These data reveal an important TSC locus near the region of PKD1 on chromosome 16p13.

Identification of the tuberous sclerosis gene TSC1 on chromosome 9q34.

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder characterized by the widespread development of distinctive tumors termed hamartomas. TSC-determining loci have been mapped to chromosomes 9q34 (TSC1) and 16p13 (TSC2). The TSC1 gene was identified from a 900-kilobase region containing at least 30 genes. The 8.6-kilobase TSC1 transcript is widely expressed and encodes a protein of 130 kilodaltons (hamartin) that has homology to a putative yeast protein of unknown function. Thirty-two distinct mutations were identified in TSC1, 30 of which were truncating, and a single mutation (2105delAAAG) was seen in six apparently unrelated patients. In one of these six, a somatic mutation in the wild-type allele was found in a TSC-associated renal carcinoma, which suggests that hamartin acts as a tumor suppressor.

Suppression of apolipoprotein B production during treatment of cholesteryl ester storage disease with lovastatin. Implications for regulation of apolipoprotein B synthesis.

Cholesteryl ester storage disease (CESD) is characterized by the deficient activity of lysosomal cholesteryl ester (CE) hydrolase, accumulation of LDL-derived CE in lysosomes, and hyperlipidemia. We studied the kinetics of VLDL and LDL apolipoprotein B (apoB), using 125I-VLDL and 131I-LDL, in a 9-yr-old female with CESD and elevated total cholesterol (TC) (271.0 +/- 4.4 mg/dl), triglyceride (TG) (150.0 +/- 7.8 mg/dl), and LDL cholesterol (184.7 +/- 3.4 mg/dl). These studies demonstrated a markedly elevated production rate (PR) of apoB, primarily in LDL, with normal fractional catabolism of apoB in VLDL and LDL. Urine mevalonate levels were elevated, indicative of increased synthesis of endogenous cholesterol. Treatment with lovastatin, a competitive inhibitor of hydroxymethylglutaryl coenzyme A reductase, resulted in significant reductions in TC (196.8 +/- 7.9 mg/dl), TG (100.8 +/- 20.6 mg/dl), and LDL cholesterol (102.0 +/- 10.9 mg/dl). Therapy reduced VLDL apoB PR (5.2 vs. 12.2 mg/kg per d pretreatment) and LDL apoB PR (12.7 vs. 24.2 mg/kg per d pretreatment). Urine mevalonate levels also decreased during therapy. These results indicate that, in CESD, the inability to release free cholesterol from lysosomal CE resulted in elevated synthesis of endogenous cholesterol and increased production of apoB-containing lipoproteins. Lovastatin reduced both the rate of cholesterol synthesis and the secretion of apoB-containing lipoproteins.

Human fetal astrocytes as an ex vivo gene therapy vehicle for delivering biologically active nerve growth factor.

The therapeutic use of neurotrophic factors for neurodegenerative diseases is promising, however, optimal methods for continuous delivery of these substances to the human central nervous system (CNS) remains problematic. One approach would be to graft genetically engineered human cells that continuously secrete high levels of a biologically produced and processed neurotrophic factor. This ex vivo gene therapy approach has worked well in animal models of neurodegenerative diseases using a variety of nonneuronal cell types to deliver the transgene. In our studies, we have been investigating the potential of astrocytes, a cell type normally present in the CNS, as a vehicle for ex vivo gene therapy. Here, we demonstrate that astrocytes in the human fetal cortex can be isolated and efficiently infected with an amphotropic retrovirus harboring mouse beta-nerve growth factor (NGF). These transduced astrocytes express high levels of NGF mRNA and secrete bioactive NGF protein as demonstrated by stimulation of neurite outgrowth from adrenal chromaffin cells. NGF ELISA showed that these astrocytes secrete NGF protein at a rate of 41 ng/day per 10(5) cells after 2 weeks in vitro, whereas NGF is undetectable in medium conditioned by normal astrocytes. These data suggest that human fetal astrocytes can be used for delivering biologically produced neurotrophic factors to the human CNS.

Clinical, neuropathological and genetic aspects of the tuberous sclerosis complex.

Tuberous sclerosis complex (TSC) is an autosomal dominant syndrome in which patients develop hamartomatous lesions in the nervous system and a host of other organs. While considerable experience has been gained in defining the clinical spectrum of TSC, a number of nosological questions remain. Neuropathological studies have continued to refine our knowledge of the nervous system abnormalities that characterize TSC. Molecular genetic studies have implicated two chromosomal regions in the genesis of TSC, one on chromosome 9q and the other on chromosome 16p. The chromosome 16p gene, designated TSC2, has been cloned, although its function remains speculative. The identification of the TSC1 gene on chromosome 9q, along with functional studies and mutational analyses of both TSC genes, will likely provide fascinating insights into the pathogenesis of TSC.

Schwannomatosis: a clinical and pathologic study.

Schwannomas are benign nerve sheath tumors that most commonly occur singularly in otherwise normal individuals. Multiple schwannomas in a single patient are most often seen in neurofibromatosis 2 (NF2), but several recent reports suggest that schwannomatosis may also be a distinct clinical entity. We studied the clinical, radiographic, and pathologic features of 14 patients with multiple schwannomas who did not have vestibular schwannoma diagnostic of NF2. Most patients had peripheral nerve tumors that presented with pain. Many also had spinal nerve root and cranial nerve tumors. Three had multiple tumors limited to a single limb. We found that these 14 individuals did not exhibit phenotypic overlap with the neurofibromatoses. Only 1 of 14 patients had a positive family history. We conclude that patients with multiple schwannomas, who do not have vestibular schwannoma, comprise a distinct clinical problem, but further molecular genetic analysis is needed to define the pathophysiology of this disorder.

CT imaging in adults with neurofibromatosis-1: frequent asymptomatic plexiform lesions.

OBJECTIVE: The authors examined the incidence and radiologic characteristics of plexiform neurofibromas in neurofibromatosis-1 (NF-1) to define a cohort at greatest risk for malignant nerve-sheath tumors. BACKGROUND: Plexiform neurofibromas are a frequent complication of NF-1. They can impair function, produce disfigurement, and be the site for the development of malignant nerve-sheath tumors. The incidence and natural history of plexiform neurofibromas is unknown. METHODS: CT imaging of the chest, abdomen, and pelvis was performed in 91 of 125 consecutive adults (age, > or = 16 years) with NF-1. RESULTS: Twenty percent of patients had plexiform neurofibromas of the chest in the paraspinal, mediastinal, or supraclavicular area. Approximately 40% of patients had abnormal abdominal/pelvic scans. The paraspinal, sacral plexus, sciatic notch, and perirectal regions were the most common sites. Most plexiform neurofibromas were asymptomatic. Imaging also revealed a number of tumors, including malignant nerve-sheath tumors, adrenal tumors, carcinoids, and schwannomas. CONCLUSIONS: The frequency of plexiform lesions and other tumors in NF-1 indicates that clinicians should monitor young adults carefully; however, imaging characteristics alone cannot reliably distinguish benign from malignant lesions.

Intracerebral implantation of nerve growth factor-producing fibroblasts protects striatum against neurotoxic levels of excitatory amino acids.

With the exception of L-DOPA pharmacological treatment in Parkinson's disease, the neurodegenerative diseases lack effective treatment. Previous studies of neurodegenerative diseases suggest that symptoms arise secondary to defects in local neuronal circuitry and cannot be treated effectively with systemic drug delivery. Therefore, a promising treatment is the application of fetal or genetically engineering cells which protect or replace neurons in deficient regions. Engineered cells can be derived from cell lines or grown from recipient host fibroblasts or other cells, then modified to produce and secrete substances at a specific area of the brain. A previous study using parallel intracerebral infusions of nerve growth factor and an excitotoxic amino acid into the rat striatum demonstrated a protective effect of nerve growth factor on neurons [Aloe L. (1987) Biotechnology 5, 1085-1086]. In order to further test this paradigm, we have utilized a biological delivery system of nerve growth factor by implanting fibroblasts into the rat striatum which secrete high levels of nerve growth factor, prior to infusing the neurotoxins quinolinate or quisqualate. Animals in this group had smaller lesions than did a group implanted with a similar non-nerve growth factor-producing graft. In addition, marked neuronal sparing was noted within areas of lesions in those animals containing a nerve growth factor-producing graft. These results indicate that implantation of genetically engineered nerve growth factor-secreting cells can be used to protect neurons at a specific target from excitotoxin-induced lesions.

Interstitial deletion of the short arm of chromosome 3 (3p14).

Deletions of 3p usually involve the terminal portion (3p25). An interstitial deletion of a proximal 3p segment (3p14) was detected at amniocentesis. The clinical and cytogenetic characteristics of this case and of three previously published cases are reviewed. Cardiovascular and gastrointestinal malformations have not been reported before in association with this particular chromosome abnormality.

Do NF1 gene deletions result in a characteristic phenotype?

Neurofibromatosis-1 (NF1) is an autosomal dominant disorder with marked variability of expression. Analysis of the NF1 gene (NF1) has detected a variety of mutations without any clear correlation with phenotype. However, deletions which remove all of NF1 have been reported in a small number of patients who have minor facial abnormalities, mental retardation, learning disabilities, and early or excessive burden of cutaneous or plexiform neurofibromas. The purpose of this study was to determine whether these phenotypic traits are associated with whole gene deletions. Out of 406 of our NF1 patients, 70 patients had manifestations previously associated with gene deletions. Thirty-five of these patients from 26 families were available for study. By fluorescence in situ hybridization (FISH) analysis, 4 were found to have deletions of the entire gene, including 2 sporadic cases, 1 familial case, and 1 case where family history could not be verified. In addition, the mother of the familial case was found to be mosaic for the deletion. Our results suggest that although large NF1 deletions occur with relatively high frequency in patients with certain findings, the presence of a deletion cannot be predicted solely on the basis of clinical phenotype.

Cholesteryl ester storage disease: pathologic changes in an affected fetus.

The prenatal diagnosis of cholesteryl ester storage disease, a rare autosomal recessive disorder, was made by demonstration of deficient lysosomal acid lipase activity in cultured amniocytes from an at-risk fetus. The histochemical and ultrastructural changes in the affected fetus (at 17 gestational weeks) are described and compared to findings in liver and duodenal biopsy specimens from a 9-year-old homozygous female. Massive lysosomal cholesterol and lipid accumulation was demonstrated in fetal hepatocytes, adrenal cells and syncytiotrophoblasts. Of particular note was the observation of extensive necrosis in the fetal adrenal glands. Necrosis of the adrenals may precede the calcification observed in some patients with cholesteryl ester storage disease and in most patients with Wolman disease, an allelic variant due to lysosomal acid lipase deficiency. Fibrosis of the liver and lipid accumulation in macrophages in liver and duodenum, which were present in the 9-year-old homozygote, were not observed in the affected fetus, and therefore, may represent later manifestations of the disease.

Descriptive analysis of tibial pseudarthrosis in patients with neurofibromatosis 1.

Five percent of individuals with neurofibromatosis type 1 (NF1) present with congenital long bone pseudarthrosis (PA). In large series, 50-80% of patients with congenital long bone PA also have NF1. Very little information exists on the natural history and pathogenesis of PA in NF1. This report is a descriptive analysis of a large series of patients with NF1 and tibial bowing or PA. Study A is a case-control study using the National Neurofibromatosis Foundation International Database (NNFFID). Eighty-five patients with PA were compared to a control group from the same database. There was a statistically significant male predominance of NF1 cases with PA (54 males to 31 females), compared to controls (85 males to 87 females) (chi2 = 4.0, P = 0.046, using a two-tailed test with Yates' correction). There was no significant difference in the clinical presentation of NF1 manifestations in NF1 patients with PA than in NF1 patients without PA. Of the affected individuals with PA, there were 24 de novo cases and 21 familial cases (9 through maternal and 12 through paternal inheritance). Questions that could not be answered by Study A were addressed by a partially overlapping case-series report, Study B, in which data on 75 cases ascertained through questionnaires completed by NF center directors were collected. From Study B we determined that half of the patients who had a fracture sustained it before age 2, and approximately 16% of the pseudarthrosis patients had an amputation. Our data indicate a male predominance and no parent-of-origin effect. Male gender may be a susceptibility factor for pseudarthrosis in NF1.

Grafting genetically modified cells into the rat brain: characteristics of E. coli beta-galactosidase as a reporter gene.

The utility of grafting genetically modified cells to the mammalian brain was examined using the E. coli beta-galactosidase gene (lacZ) as a reporter gene in retroviral infection. Following implantation of the infected cells to the brain, lacZ continued to be expressed in vivo and could be detected easily with enzyme histochemistry. However, beta-galactosidase-positive cells were also observed in control grafts which had not been infected with the virus. This false-positive staining was found to be endogenous lysosomal activity associated with macrophage infiltration presumably induced by the damage associated with grafting. The E. coli gene product was distinguished from cellular lysosomal beta-galactosidase by using immunohistochemical staining with an antibody specific for E. coli beta-galactosidase. With this antibody, retrovirus-infected cells could be distinguished in the brain, and no false positives were observed in non-infected cells. We conclude that E. coli beta-galactosidase is a useful reporter gene for determining the fate of implanted cells to the brain if appropriate caution is taken to distinguish it from cellular beta-galactosidase by immunocytochemical procedures.

Effects of biologically delivered NGF, BDNF and bFGF on striatal excitotoxic lesions.

Immortalized rat fibroblasts, genetically altered to secrete NGF, BDNF, and bFGF, were implanted in rat brain near the striatum 7 days before striatal infusion of excitotoxic quantities of an NMDA-receptor agonist. Analysis of striatal damage 7 days after lesioning revealed that implantation of NGF-secreting cells reduced the size of the excitotoxic lesions by more than 80% when compared with control cells, while implanting of bFGF-secreting cells caused a 30% decrease in excitotoxic lesion size. BDNF-secreting fibroblasts caused no protective sparing in the striatum in this lesion model. This finding shows that biological delivery of NGF and bFGF by grafting of genetically altered cells protects against glutamate toxicity in the adult striatum while grafting of BDNF-producing cells does not. Such observations begin to define a spectrum of neurotrophic agents able to mitigate the cell loss seen in neurodegeneration.

Nerve growth factor released by transgenic astrocytes enhances the function of adrenal chromaffin cell grafts in a rat model of Parkinson's disease.

Previous studies have demonstrated that astrocytes genetically modified to express recombinant nerve growth factor (NGF) support the survival and neuronal transdifferentiation of intrastriatal adrenal chromaffin cell grafts at 2 weeks post-transplantation [15]. The present study was performed to determine whether these effects would be maintained at longer times post-transplantation and, if so, whether the co-grafts would reduce rotational behavior in the unilateral 6-hydroxydopamine-lesioned rat. In the present study, we have demonstrated that primary type I rat astrocytes infected with a replication-defective retrovirus conferring expression of a mouse beta-NGF cDNA sequence secrete NGF at a rate that is approximately 40-fold higher than that of controls (i.e., 8.0 vs. 0.2 pg NGF/h/10(5) cells, respectively). The genetically modified astrocytes were also found to express recombinant NGF following intrastriatal transplantation, as indicated by a 23% increase in striatal NGF content compared with controls, measured at 4 weeks post-transplantation. When NGF-producing astrocytes and adrenal chromaffin cells were co-grafted into the dopamine-denervated striatum of the unilateral 6-hydroxydopamine-lesioned rat, the chromaffin cells displayed extensive neurite outgrowth and a 5-12-fold increase in survival compared to controls at 10 weeks post-grafting. These effects were paralleled by a 60% reduction of apomorphine-induced rotational behavior, suggesting a partial normalization of striatal function. These results suggest that genetically modified astrocytes promote the prolonged survival and function of adrenal chromaffin cell grafts in a rat model of Parkinson's disease.

The use of genetically altered astrocytes to provide nerve growth factor to adrenal chromaffin cells grafted into the striatum.

Transplantation of adrenal chromaffin cells into the striatum of Parkinson's disease patients is unlikely to become a reliable therapy unless techniques are devised to improve cell survival. To address this issue, we investigated the use of genetically altered astrocytes that constitutively secrete beta-nerve growth factor (NGF) to provide trophic support for adrenal chromaffin cells grafted into the dopamine-denervated striatum of the rat. Primary rat astrocytes were altered genetically in vitro by infection with a retroviral vector harboring a mouse beta-NGF transgene under constitutive long terminal repeat transcriptional control. Confluent cultures of these genetically altered astrocytes secrete NGF into their culture medium at a rate of approximately 9 pg/10(5) cells/h. This rate of NGF secretion is at least 10-fold higher than that of confluent sister cultures of uninfected astrocytes. The effects of the NGF-secreting astrocytes on the survival and neuronal transformation of dissociated adrenal chromaffin cells were assessed in vitro and following transplantation into the dopamine-denervated striatum of the adult rat. In vitro experiments demonstrated that neuritic outgrowth is stimulated when postnatal day 12 chromaffin cells are grown on a monolayer of the genetically altered astrocytes. When co-grafted with genetically altered astrocytes, young postnatal chromaffin cells displayed extensive neuritic outgrowth within the host brain 2 weeks postimplantation, whereas chromaffin cells grafted alone or with normal astrocytes retain an endocrine-like morphology. Survival of the chromaffin cells is also enhanced 3-6-fold when co-grafted with the genetically altered astrocytes. In addition, the neuronally transformed chromaffin cells appear to lose adrenergic properties as assessed by diminished immunoreactivity to the adrenergic marker, phenylethanolamine-N-methyltransferase. Although their survival is also enhanced approximately 4-fold relative to controls, adult chromaffin cells do not convert to a neuronal morphology when co-grafted with the genetically altered astrocytes. These studies demonstrate that rat astrocytes carrying a mouse NGF transgene provide trophic support for intrastriatal chromaffin cell grafts.

Tuberous sclerosis.

BACKGROUND AND DESIGN: Tuberous sclerosis (TS) is a genetic disease with prominent cutaneous and brain involvement whose clinical and molecular genetics are reviewed. OBSERVATIONS: Tuberous sclerosis is a systemic disorder (incidence one in 10,000) characterized by benign growths (hamartias and hamartomas) in multiple organ systems. Involvement of the brain can result in persistent seizures and mental retardation; skin involvement includes facial angiofibromas, subungual fibromas, hypomelanotic macules, forehead fibrous plaques, and Shagreen's patches. Approximately 60% of TS occurs as apparent sporadic cases. In families, it has autosomal dominant inheritance with high penetrance (approximately 95%), with careful clinical and radiologic evaluation. Genetic linkage analysis indicates that about half of all TS families show linkage to chromosome 9q34, and about half to chromosome 16p13. There are no distinguishing features in the two groups of families showing linkage to the two genomic regions, nor strong evidence for a third causative gene. Positional cloning efforts for both chromosomal regions have limited the region containing the gene to about 1 to 2 million bases. CONCLUSIONS: Identification of the two TS genes should illuminate the pathogenesis of TS and provide opportunities for genetic counseling, prenatal diagnosis, and therapeutic intervention.

Deep sylvian fissure meningioma without dural attachment in an adult: case report.

Meningiomas are thought to arise from arachnoid cap or meningothelial cells that not only cluster on the surface of pacchionian granulations but also can cover the arachnoid membrane in other locations. This frequent apposition to the dura mater probably accounts for the usual attachment of the neoplasm to this layer. We report a deep sylvian fissure meningioma without dural attachments in the right hemisphere of an adult patient. The patient initially presented with simple partial seizures. Magnetic resonance imaging revealed a contrast-enhancing circular mass in the superior aspect of the insular region, deep to the inferior parietal lobule. Surgical exploration confirmed the absence of dural attachments. Microscopically, the tumor was found to be a sparsely cellular meningioma with an extensive collagenous matrix. A survey of the literature reveals that the majority of cases of meningiomas without dural attachments occur either in children or below the tentorium. Extremely rare cases of supratentorial meningiomas without dural attachment have been described in adults. The uncommon locations of these tumors at sites distant from the dura mater is postulated to reflect the rare occurrence of arachnoidal cap cells in the Virchow-Robin spaces along the cerebral vasculature or in pial layers distant from the dura mater.

Local protective effects of nerve growth factor-secreting fibroblasts against excitotoxic lesions in the rat striatum.

Neurotrophic factors, such as nerve growth factor (NGF), in addition to their role in neuronal development, have protective effects on neuronal survival. Intracerebral implantation of cells genetically altered to secrete high levels of NGF is also found to promote neuronal survival in experimental lesioning models of the brain. The range of activity for such biological delivery systems has not yet been well described either spatially or temporally. Therefore, the authors chose to study the local and distant protective effects of an NGF-secreting rat fibroblast cell line implanted in an excitotoxic lesion model of Huntington's disease. They found that preimplantation of NGF-secreting fibroblasts placed within the corpus callosum reduced the maximum cross-sectional area of a subsequent excitotoxic lesion in the ipsilateral striatum by 80% when compared to the effects of a non-NGF-secreting fibroblast graft, and by 83% when compared to excitotoxic lesions in ungrafted animals (p < 0.003). However, NGF-secreting cells placed in the contralateral corpus callosum failed to affect striatal lesion size significantly when compared to contralateral or ipsilateral non-NGF-secreting cell implants. Of note, fibroblasts were clearly visible within the graft site at 7 and 18 days after implantation; however, few cells within the grafts stained positively for NGF peptide or for the messenger ribonucleic acid (mRNA) encoding the transfected NGF gene-construct at either time point. These results show that biological delivery systems for NGF appear to have a profound but local effect on neuronal excitotoxicity, which will necessitate careful neurosurgical placement for maximum effect. Furthermore, the ability of this genetically altered cell line to synthesize NGF mRNA and peptide appears to decrease spontaneously in vivo, a characteristic that will need to be addressed before this method of biological delivery can be utilized as a treatment for chronic degenerative diseases.