[show abstract][hide abstract] ABSTRACT: Canavan's disease (CD) is a fatal pediatric leukodystrophy caused by mutations in aspartoacylase (AspA) gene. Currently, there is no effective treatment for CD; however, gene therapy is an attractive approach to ameliorate the disease. Here, we studied progressive neuropathology and gene therapy in short-lived (≤1 month) AspA(-/-) mice, a bona-fide animal model for the severest form of CD. Single intravenous (IV) injections of several primate-derived recombinant adeno-associated viruses (rAAVs) as late as postnatal day 20 (P20) completely rescued their early lethality and alleviated the major disease symptoms, extending survival in P0-injected rAAV9 and rAAVrh8 groups to as long as 2 years thus far. We successfully used microRNA (miRNA)-mediated post-transcriptional detargeting for the first time to restrict therapeutic rAAV expression in the central nervous system (CNS) and minimize potentially deleterious effects of transgene overexpression in peripheral tissues. rAAV treatment globally improved CNS myelination, although some abnormalities persisted in the content and distribution of myelin-specific and -enriched lipids. We demonstrate that systemically delivered and CNS-restricted rAAVs can serve as efficacious and sustained gene therapeutics in a model of a severe neurodegenerative disorder even when administered as late as P20.Molecular Therapy (2013); doi:10.1038/mt.2013.138.
[show abstract][hide abstract] ABSTRACT: Complex chromosome rearrangements (CCRs) are structural abnormalities involving >2 chromosomes or >3 breakpoints. It has been suggested that the probability of imbalance increases as the number of breakpoints increase. Here we report a 7-month-old, Hispanic girl presenting with cleidocranial dysplasia (CCD) who was found to have a complex chromosome rearrangement of chromosome 6. Fluorescence in situ hybridization studies with bacterial artificial chromosome (BAC) clones showed that the rearrangement involved insertion of 6q into 6p disrupting the "Runt related transcription factor 2 (RUNX2)" gene at chromosome 6p21.1. In addition, a pericentric inversion of chromosome 6 was identified. Despite the complex nature of the rearrangement, no cryptic deletions or duplications could be detected by array comparative genomic hybridization.
European journal of medical genetics 04/2011; 54(4):e394-8. · 1.57 Impact Factor
[show abstract][hide abstract] ABSTRACT: BACKGROUND: We have previously shown an association between polymorphisms of proinflammatory cytokine genes and susceptibility to upper respiratory tract infection and acute otitis media. It has not been known whether polymorphisms or risk factors are associated with the severity of acute otitis media. OBJECTIVE: To evaluate the influences of proinflammatory cytokine gene polymorphisms and other risk factors on severity of acute otitis media following upper respiratory tract infection. METHODS: In a prospective, longitudinal study, children aged 6-35 months were followed for one year for occurrences of upper respiratory tract infection and acute otitis media. Children were studied for TNFα(-308), interleukin (IL)-6(-174) and IL-1β(+3953) polymorphisms, taking into account age, gender, race, family history of otitis, tobacco smoke exposure, breast feeding, day of upper respiratory tract infection at the time of diagnosis and pneumococcal vaccine status. Symptoms and signs of acute otitis media were graded according to a validated scale. The association between acute otitis media clinical severity, polymorphic genotypes, and risk factors were analyzed using statistical models that account for multiple episodes of acute otitis media per child. RESULTS: A total of 295 episodes of acute otitis media in 128 subjects was included. More severe acute otitis media symptoms were associated with young age (P=0.01), family history of acute otitis media (P=0.002), tobacco smoke exposure (P=0.008), and early diagnosis of otitis after onset of upper respiratory tract infection (P=0.02). Among children with a bulging or perforated tympanic membrane (206 episodes, 104 subjects), those who had the IL-1 β(+3953) polymorphism, experienced higher symptom scores (P<0.02). CONCLUSION: This is the first report of the association between risk factors and acute otitis media severity. Risk factors such as tobacco smoke exposure and a positive family history appear to be more significantly associated with acute otitis media severity than proinflammatory gene polymorphisms. Clinical severity may be an important factor contributing to the incidence and costs of acute otitis media, because children with more severe symptoms might be more likely to be brought for a medical visit, receive a diagnosis of acute otitis media, and be prescribed an antibiotic.
International journal of pediatric otorhinolaryngology 03/2011; · 0.85 Impact Factor
[show abstract][hide abstract] ABSTRACT: Canavan disease is a fatal neurological disease without any effective treatments to slow the relentless progress of this disorder. Enzyme replacement therapy has been used effectively to treat a number of metabolic disorders, but the presence of the blood-brain-barrier presents an additional challenge in the treatment of neurological disorders. Studies have begun with the aim of establishing a treatment protocol that can effectively replace the defective enzyme in Canavan disease patients. The human enzyme, aspartoacylase, has been cloned, expressed and purified, and the surface lysyl groups modified through PEGylation. Fully active modified enzymes were administered to mice that are defective in this enzyme and that show many of the symptoms of Canavan disease. Statistically significant increases in brain enzyme activity levels have been achieved in this animal model, as well as decreases in the elevated substrate levels that mimic those found in Canavan disease patients. These results demonstrate that the modified enzyme is gaining access to the brain and functions to correct this metabolic defect. The stage is now set for a long term study to optimize this enzyme replacement approach for the development of a treatment protocol.
Molecular Genetics and Metabolism 02/2011; 102(2):176-80. · 2.83 Impact Factor
[show abstract][hide abstract] ABSTRACT: Canavan disease (CD) is a neurodegenerative disease, caused by a deficiency in the enzyme aspartoacylase (ASPA). This enzyme has been localized to oligodendrocytes; however, it is still undefined how ASPA deficiency affects oligodendrocyte development. In normal mice the pattern of ASPA expression coincides with oligodendrocyte maturation. Therefore, postnatal oligodendrocyte maturation was analyzed in ASPA-deficient mice (CD mice). Early in development, CD mice brains showed decreased expression of neural cell markers that was later compensated. In addition, the levels of myelin proteins were decreased along with abnormal myelination in CD mice compared to wild-type (WT). These defects were associated with increased global levels of acetylated histone H3, decreased chromatin compaction and increased GFAP protein, a marker for astrogliosis. Together, these findings strongly suggest that, early in postnatal development, ASPA deficiency affects oligodendrocyte maturation and myelination.
Neurobiology of Disease 11/2010; 40(2):432-43. · 5.62 Impact Factor
[show abstract][hide abstract] ABSTRACT: Goldenhar syndrome, also called hemifacial microsomia or oculo-auriculo-verterbal dysplasia (OAVS) (MIM 164210), is a birth defect involving the first and second branchial arch derivatives with an incidence of 1/5000. The variable phenotype includes mostly unilateral deformity of the external ear and small ipsilateral half of the face with epibulbar dermoid and vertebral anomalies. A genome-wide search in one family suggested linkage to a region of 10.7 cM on chromosome 14q32; however, no candidate genes have been identified. We report on a 9-month old with OAVS and a pericentric inversion of chromosome 14 which he inherited from his phenotypically normal mother. Fluorescence in-situ hybridization analysis with bacterial artificial chromosome clones from chromosome 14 showed the breakpoint on 14q maps distal to 14q21.2, thus confirming the cytogenetic breakpoints. In light of previous linkage studies mapping OAVS to 14q, we propose that the long arm breakpoint in our proband disrupted a potential candidate gene for OAVS resulting in his clinical phenotype.
[show abstract][hide abstract] ABSTRACT: The NIPSNAP (4-nitrophenylphosphatase domain and non-neuronal SNAP25-like protein homolog 1) proteins belong to a highly conserved family of proteins of unknown function. We found that NIPSNAP1 binds to the branched-chain alpha-keto acid (BCKA) dehydrogenase enzyme complex, which is disrupted in maple syrup urine disease, a disease of branched-chain amino acid catabolism that results in neurological dysfunction. Phenylketonuric (PKU) and epileptic mice show altered expression of NIPSNAP1 in the brain. Therefore, the distribution and localization of NIPSNAP1 in rat brain was determined. Results show that NIPSNAP1 is expressed exclusively in neurons including pyramidal neurons in the cerebral cortex, Purkinje neurons in the cerebellum and motor neurons in the spinal cord. Dopaminergic neurons in midbrain and noradrenergic neurons in the brainstem, which are affected in PKU, also express NIPSNAP1. NIPSNAP1 is found to be localized in the mitochondrial matrix and can bind dihydrolipoyl-transacylase and -transacetylase components of the BCKA and pyruvate dehydrogenase complexes in vitro. Our data provide the first experimental evidence for a strictly neuronal expression of this mitochondrial protein in the rat nervous system.
European Journal of Neuroscience 08/2010; 32(4):560-9. · 3.75 Impact Factor
[show abstract][hide abstract] ABSTRACT: Loss of the oligodendrocyte (OL)-specific enzyme aspartoacylase (ASPA) from gene mutation results in the sponginess and loss of white matter (WM) in Canavan disease (CD). This study addresses the fate of OLs during the pathophysiology of CD in an adult ASPA knockout (KO) mouse strain. Massive arrays of neural stem/progenitor cells, immunopositive for PSA-NCAM, nestin, vimentin, and NG2, were observed within the severely affected spongy WM of the KO mouse brain. In these mice, G1-->S cell cycle progression was confirmed by an increase in cdk2-kinase activity, a reduction in mitotic inhibitors p21(Cip1) and p27(Kip1), and an increase in bromodeoxyuridine (BrdU) incorporation. Highly acetylated nuclear histones H2B and H3 were detected in adult KO mouse WM, suggesting the existence of noncompact chromatin as seen during early development. Costaining for BrdU- or Ki67-positive cells with markers for neural progenitors confirmed a continuous generation of OL lineage cells in KO WM. We observed a severe reduction in 21.5- and 18.5-kDa myelin basic protein and PLP/DM20 proteolipid proteins combined with a decrease in myelinated fibers and a perinuclear retention of myelin protein staining, indicating impairment in protein trafficking. Death of OLs, neurons, and astrocytes was identified in every region of the KO brain. Immature OLs constituted the largest population of dying cells, particularly in WM. We also report an early expression of full-length ASPA mRNA in normal mouse brain at embryonic day 12.5, when OL progenitors first appear during development. These findings support involvement of ASPA in CNS development and function.
Journal of Neuroscience Research 09/2009; 87(15):3415-27. · 2.97 Impact Factor
[show abstract][hide abstract] ABSTRACT: We previously reported an association between tumor necrosis factor alpha (TNFalpha)(-308)and interleukin (IL)-6(-174) polymorphisms and otitis susceptibility by history. Acute otitis media occurs most commonly as a complication of upper respiratory tract infection (URI); it is not clear why some children develop acute otitis media after URI and others do not. Our objective was to prospectively evaluate the association of TNFalpha(-308)and IL-6(-174) polymorphisms with URI and with acute otitis media development after URI.
Children aged 6-35 months were prospectively followed for occurrences of URI and acute otitis media. Blood or buccal mucosa samples were collected for DNA extraction to determine cytokine genotypes. Active and passive surveillance was used to capture all URI episodes during the 1-year follow-up period in order to study the rate of acute otitis media following URI. Data were analyzed using SAS software (SAS Institute) and general estimating equations modeling.
Two hundred forty-two children were followed over 2689 patient-months and had DNA genotyped; 1235 URI episodes occurred, and 392 (32%) were complicated by acute otitis media. Children who had IL-6(-174) polymorphism had a higher susceptibility to URI during the study period (incidence density ratio, 1.24) and were more likely to meet established otitis susceptibility criteria (P < .01). Presence of TNFalpha(-308) polymorphism was associated with increased risk for acute otitis media after an episode of URI (odds ratio, 1.43).
TNFalpha(-308) and IL-6(-174) genotypes are associated with increased risk for symptomatic URI and acute otitis media following URI. Future studies may be designed to carefully look at the interaction of these genetic polymorphisms with modifiable environmental risk factors.
[show abstract][hide abstract] ABSTRACT: A favorable response, indicated by decline of blood phenylalanine (Phe) in patients with phenylketonuria (PKU), to orally administered 6-R-L-erythro-5, 6, 7, 8-tetrahydrobiopterin (BH4) has been reported in many countries following the first publication in 1999. In this review, we describe the experience in the United States with PKU patients and their response to BH4. A significant response to BH4 is arbitrarily considered as a decrease of 30% or greater of blood Phe concentration 24 h after administration of BH4. In our studies, 18 of 37 patients with PKU (49%) responded to oral BH4 by >30% decrease in blood Phe concentration. Four PKU patients responded with a decrease of blood Phe concentration between 17.3 and 26.3%. It is suggested that patients with sufficient response to BH4 are candidates who will benefit from BH4 as it becomes available for PKU management. In a separate trial, 20 patients with PKU were screened with ascending doses of BH4: 10, 20, and 40 mg/kg. A favorable response was found in 10 subjects (50%) after 10 mg/kg BH4 and 14 subjects (70%) after 20 mg/kg BH4. There was no additional advantage to 40 mg/kg BH4. A 1-wk trial with 10 and 20 mg/kg BH4 in the same 20 patients showed blood Phe concentrations lowest after 7 d of BH4. The BH4-responsive patients were genotyped and most were compound heterozygotes with 1 mild mutation on 1 allele, responsible for the increase of the residual activity of Phe hydroxylase when BH4 was added. Individuals with the same genotype exhibit different responses upon administration of BH4, attributed to epigenetic factors, such as the metabolic makeup of the individual. Patients with PKU, regardless of their genotype or classification, need to be screened for response to BH4. The majority of patients are identified by 10 mg/kg BH4.
[show abstract][hide abstract] ABSTRACT: The growing use of N-acetylaspartate as an indicator of neuronal viability has fostered interest in the biological function(s) of this unusual amino acid derivative. In considering the various physiological roles that have been proposed for this relatively abundant molecule one is obliged to take into account its unusual metabolic compartmentalization, according to which synthesis and storage occur in the neuron and hydrolytic cleavage in the oligodendrocyte. The latter reaction, catalyzed by aspartoacylase (ASPA), produces acetyl groups plus aspartate and has been proposed to occur in both soluble and membranous subfractions of white matter. Our study supports such bimodal occurrence and we now present immunoblot, proteomic, and biochemical evidence that the membrane-bound form of ASPA is intrinsic to purified myelin membranes. This was supported by a novel TLC-based method for the assay of ASPA. That observation, together with previous demonstrations of numerous lipid-synthesizing enzymes in myelin, suggests utilization of acetyl groups liberated by myelin-localized ASPA for lipid synthesis within the myelin sheath. Such synthesis might be selective and could explain the deficit of myelin lipids in animals lacking ASPA.
Journal of Neurochemistry 05/2007; 101(2):448-57. · 3.97 Impact Factor
[show abstract][hide abstract] ABSTRACT: The Spontaneously Epileptic Rat (SER), a double-mutant for tremor and zitter mutations, shows spontaneous occurrences of absence-like and tonic seizures. Several lines of evidence suggest that the combined effect of Aspa and Atrn mutations is the most likely cause of the epileptic phenotype of the SER. To address this issue, we produced a new double-mutant mouse line carrying both homozygous Aspa-knockout and Atrn(mg-3J) mutant alleles. The Aspa/Atrn double-mutant mice exhibited absence-like and tonic seizures that were characterized by the appearance of 5-7 Hz spike-wave-like complexes and low voltage fast waves on EEGs. These results demonstrate directly that the simultaneous loss of the Aspa and Atrn gene functions causes epileptic seizures in the mouse and suggest that both Aspa and Atrn deficiencies might be responsible for epileptic seizures in the SER.
[show abstract][hide abstract] ABSTRACT: Tetrahydrobiopterin (BH4) is a co-factor that enhances the activity of other enzymes, and this co-factor level is found to be affected in phenylketonuria (PKU), an amino acid metabolism disorder. The present study was aimed at understanding the effect of BH4 on mutations in the regulatory domain of phenylalanine hydroxylase (PAH). Among 14 patients, 5 patients were classical PKU, 3 were atypical PKU, and 6 were mild PKU. All of these patients had at least one mutation in the regulatory domain. Patients were given 10 mg/kg BH4, and the response of blood phenylalanine (Phe) levels was monitored following treatment. The level of blood Phe decreased after BH4 treatment in all of the patients. These studies suggest that mutations in the regulatory domain also responded to BH4 even if the patient had classical PKU.
[show abstract][hide abstract] ABSTRACT: Susceptibility to otitis media results from complex interactions among genetic factors of the host, exposure to pathogens, and environmental influences. The objective of this study was to study the role of single-nucleotide polymorphisms of regulatory elements of proinflammatory cytokine genes tumor necrosis factor-alpha(-308), interleukin-1beta(+3953), and interleukin-6(-174), in susceptibility to recurrent otitis media in childhood.
A total of 505 children (296 otitis media susceptible, 209 nonsusceptible as control) were enrolled at 2 sites (Texas and Kentucky). DNA of the children was studied for specific single-nucleotide polymorphisms by restriction fragment length polymorphism assay and confirmed by gene sequencing.
In the overall study group, tumor necrosis factor-alpha(-308) and interleukin-6(-174) heterozygous or homozygous polymorphisms (high cytokine-producing genotypes) were significantly associated with otitis media susceptibility. The same association was found in a match-paired subgroup of 384 subjects. In the overall study group, there was a significant step-wise increase in otitis media susceptibility with increasing number of concomitant polymorphic genotypes. Simultaneous combination of tumor necrosis factor-alpha(-308) and interleukin-6(-174) polymorphisms further increased the risk for otitis media susceptibility. These 2 polymorphic genotypes also were associated with the increased risk for tympanostomy tube placement. Children who had tumor necrosis factor-alpha(-308) polymorphism and were breastfed for <1 month or exposed to cigarette smoke were more likely to be otitis media susceptible.
Our data suggest that tumor necrosis factor-alpha(-308) and interleukin-6(-174) polymorphisms are associated with increased risk for otitis media susceptibility and placement of tympanostomy tubes. Environmental factors such as breastfeeding may modify the risk for otitis media susceptibility in polymorphic individuals.
[show abstract][hide abstract] ABSTRACT: Pompe disease (glycogen storage disease type II) is a glycogen storage disease caused by a deficiency of the lysosomal enzyme, acid maltase/acid alpha-1,4 glucosidase (GAA). Deficiency of the enzyme leads primarily to intra-lysosomal glycogen accumulation, primarily in cardiac and skeletal muscles, due to the inability of converting glycogen into glucose. Enzyme replacement therapy (ERT) has been applied to replace the deficient enzyme and to restore the lost function. However, enhancing the enzyme activity to the muscle following ERT is relatively insufficient. In order to enhance GAA activity into the muscle in Pompe disease, efficacy of hyaluronidase (hyase) was examined in the heart, quadriceps, diaphragm, kidney, and brain of mouse model of Pompe disease. Administration of hyase 3000 U/mouse (intravenous) i.v. or i.p. (intraperitoneal) and 10 min later recombinant human GAA (rhGAA) 20 mg/kg i.v. showed more GAA activity in hyase i.p. injected mice compared to those mice injected with hyase via i.v. Injection of low dose of hyase (3000 U/mouse) or high dose of hyase (10,000 U/mouse) i.p. and 20 min or 60 min later 20 mg/kg rhGAA i.v. increased GAA activity into the heart, diaphragm, kidney, and quadriceps compared to hyase untreated mice. These studies suggest that hyase enhances penetration of enzyme into the tissues including muscle during ERT and therefore hyase pretreatment may be important in treating Pompe disease.
Biochemical and Biophysical Research Communications 12/2006; 350(3):783-7. · 2.41 Impact Factor