J J Hopwood

South Australian Health and Medical Research Institute, Adelaide Hills, South Australia, Australia

Are you J J Hopwood?

Claim your profile

Publications (418)1720.68 Total impact

  • Paul J Trim · John J Hopwood · Marten F Snel
    [Show abstract] [Hide abstract]
    ABSTRACT: Heparan sulfate (HS) is a complex oligosaccharide that is a marker of a number of diseases, most notably several of the mucopolysaccharidoses (MPS). It is a very heterogeneous compound and its quantification at physiological concentrations in patient samples is challenging. Here, we demonstrate novel derivatization chemistry for depolymerization/desulfation and alkylation of HS based on butanolysis. The resultant alkylated disaccharides are quantifiable by LC-MS/MS. This new method is at least 70-fold more sensitive than a previously published methanolysis method. Disaccharide yield over time is compared for methanolysis, ethanolysis, and butanolysis. Maximum disaccharide concentration was observed after 2 h with butanolysis and 18 h with ethanolysis whereas a maximum was not reached over the 24 h of the experiment with methanolysis. The sensitivity of the new technique is illustrated by the quantification of HS in 5 μL urine samples from MPS patients and healthy controls. HS was quantifiable in all samples including controls. Disaccharide reaction products were further characterized using exact mass MS/MS.
    Analytical Chemistry 08/2015; 87(18). DOI:10.1021/acs.analchem.5b01743 · 5.64 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: MPS IIIA is an inherited neurodegenerative lysosomal storage disorder characterized by cognitive impairment, sleep-wake cycle disturbance, speech difficulties, eventual mental regression and early death. Neuropathological changes include accumulation of heparan sulfate and glycolipids, neuroinflammation and degeneration. Pre-clinical animal studies indicate that replacement of the deficient enzyme, sulfamidase, via intra-cerebrospinal fluid (CSF) injection is a clinically-relevant treatment approach, reducing neuropathological changes and improving symptoms. Given that there are several routes of administration of enzyme into the CSF (intrathecal lumbar, cisternal and ventricular), determining the effectiveness of each injection strategy is crucial in order to provide the best outcome for patients. We delivered recombinant human sulfamidase (rhSGSH) to a congenic mouse model of MPS IIIA via each of the three routes. Mice were euthanized 24h or one-week post-injection; the distribution of enzyme within the brain and spinal cord parenchyma was investigated, and the impact on primary substrate levels and other pathological lesions determined. Both ventricular and cisternal injection of rhSGSH enable enzyme delivery to brain and spinal cord regions, with the former mediating large, statistically significant decreases in substrate levels and reducing microglial activation. The single lumbar CSF infusion permitted more restricted enzyme delivery, with no reduction in substrate levels and little change in other disease-related lesions in brain tissue. While the ventricular route is the most invasive of the three methods, this strategy may enable the widest distribution of enzyme within the brain, and thus requires further exploration. Copyright © 2015 Elsevier Inc. All rights reserved.
    Molecular Genetics and Metabolism 03/2015; 115(1). DOI:10.1016/j.ymgme.2015.03.002 · 2.63 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Recombinant vectors based on adeno-associated virus serotype 8 (AAV8) have been successfully used in the clinic and hold great promise for liver-directed gene therapy. Pre-existing immunity against AAV8 or the development of antibodies against the therapeutic transgene product might negatively affect the outcomes of gene therapy. In the prospect of an AAV8-mediated, liver-directed gene therapy clinical trial for Mucopolysaccharidosis VI (MPS VI), a lysosomal storage disorder due to arylsulfatase B (ARSB) deficiency, we investigated in a multiethnic cohort of MPS VI patients the prevalence of neutralizing antibodies (Nab) to AAV8 and the presence of ARSB cross-reactive immunologic material (CRIM), which will either affect the efficacy of gene transfer or the duration of phenotypic correction. Thirty-six MPS VI subjects included in the study harbored 45 (62.5%) missense, 13 (18%) nonsense, 9 (12.5%) frameshift (2 insertions and 7 deletions), and 5 (7%) splicing ARSB mutations. The detection of ARSB protein in twenty-four patients out of 34 (71%) was predicted by the type of mutations. Pre-existing Nab to AAV8 were undetectable in 19/33 (58%) analyzed patients. Twelve out of 31 patients (39%) tested were both negative for Nab to AAV8 and CRIM-positive. In conclusion, this study allows estimating the number of MPS VI patients eligible for a gene therapy trial by intravenous injections of AAV8.
    Human Gene Therapy 02/2015; 26(3). DOI:10.1089/hum.2014.109 · 3.76 Impact Factor
  • Source
    Kerryn Mason · Peter Meikle · John Hopwood · Maria Fuller
    [Show abstract] [Hide abstract]
    ABSTRACT: Heparan sulfate (HS) catabolism begins with endo-degradation of the polysaccharide to smaller HS oligosaccharides, followed by the sequential action of exo-enzymes to reduce these oligosaccharides to monosaccharides and inorganic sulfate. In mucopolysaccharidosis type IIIA (MPS IIIA) the exo-enzyme, N-sulfoglucosamine sulfohydrolase, is deficient resulting in an inability to hydrolyze non-reducing end glucosamine N-sulfate esters. Consequently, partially degraded HS oligosaccharides with non-reducing end glucosamine sulfate esters accumulate. We investigated the distribution of these HS oligosaccharides in tissues of a mouse model of MPS IIIA using high performance liquid chromatography electrospray ionization-tandem mass spectrometry. Oligosaccharide levels were compared to total uronic acid (UA), which was used as a measure of total glycosaminoglycan. Ten oligosaccharides, ranging in size from di- to hexasaccharides, were present in all the tissues examined including brain, spleen, lung, heart, liver, kidney and urine. However, the relative levels varied up to 10-fold, suggesting different levels of HS turnover and storage. The relationship between the di- and tetrasaccharides and total UA was tissue specific with spleen and kidney showing a different disaccharide:total UA ratio than the other tissues. The hexasaccharides showed a stronger correlation with total UA in all tissue types suggesting that hexasaccharides may more accurately reflect the storage burden in these tissues.
    12/2014; 4(4):1088-100. DOI:10.3390/metabo4041088
  • [Show abstract] [Hide abstract]
    ABSTRACT: Intracerebrospinal fluid (CSF) infusion of replacement enzyme is under evaluation for amelioration of disease-related symptoms and biomarker changes in patients with the lysosomal storage disorder mucopolysaccharidosis type IIIA (MPS IIIA; www.clinicaltrials.gov ; NCT#01155778; #01299727). Determining the optimal dose/dose-frequency is important, given the invasive method for chronically supplying recombinant protein to the brain, the main site of symptom generation. To examine these variables, we utilised MPS IIIA Huntaway dogs, providing recombinant human sulphamidase (rhSGSH) to young pre-symptomatic dogs from an age when MPS IIIA dog brain exhibits significant accumulation of primary (heparan sulphate) and secondary (glycolipid) substrates. Enzyme was infused into CSF via the cisterna magna at one of two doses (3 mg or 15 mg/infusion), with the higher dose supplied at two different intervals; fortnightly or monthly. Euthanasia was carried out 24 h after the final injection. Dose- and frequency-dependent reductions in heparan sulphate were observed in CSF and deeper layers of cerebral cortex. When we examined the amount of immunostaining of the general endo/lysosomal marker, LIMP-2, or quantified activated microglia, the higher fortnightly dose resulted in superior outcomes in affected dogs. Secondary lesions such as accumulation of GM3 ganglioside and development of GAD-reactive axonal spheroids were treated to a similar degree by both rhSGSH doses and dose frequencies. Our findings indicate that the lower fortnightly dose is sub-optimal for ameliorating existing and preventing further development of disease-related pathology in young MPS IIIA dog brain; however, increasing the dose fivefold but halving the frequency of administration enabled near normalisation of disease-related biomarkers.
    Journal of Inherited Metabolic Disease 11/2014; 38(2). DOI:10.1007/s10545-014-9790-8 · 3.37 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Injection of lysosomal enzyme into cisternal or ventricular cerebrospinal fluid (CSF) has been carried out in 11 lysosomal storage disorder models, with each study demonstrating reductions in primary substrate and secondary neuropathological changes, and several reports of improved neurological function. Whilst acute studies in mucopolysaccharidosis (MPS) type II mice revealed that intrathecally-delivered enzyme (into thoraco-lumbar CSF) accesses the brain, the impact of longer-term treatment of affected subjects via this route is unknown. This approach is presently being utilized to treat children with MPS types I, II and III. Our aim was to determine the efficacy of repeated intrathecal injection of recombinant human sulfamidase (rhSGSH) on pathological changes in the MPS IIIA dog brain. The outcomes were compared with those in dogs treated via intra-cisternal or ventricular routes. Control dogs received buffer or no treatment. Significant reductions in primary/secondary substrate levels in brain were observed in dogs treated via all routes, although the extent of the reduction differed regionally. Treatment via all CSF access points resulted in large reductions in microgliosis in superficial cerebral cortex, but only ventricular injection enabled amelioration in deep cerebral cortex. Formation of glutamic acid decarboxylase-positive axonal spheroids in deep cerebellar nuclei was prevented by treatment delivered via any route. Anti-rhSGSH antibodies in the sera of some dogs did not reduce therapeutic efficacy. Our data indicates the capacity of intra-spinal CSF-injected rhSGSH to circulate within CSF-filled spaces, penetrate into brain and mediate a significant reduction in substrate accumulation and secondary pathology in the MPS IIIA dog brain.
    Experimental Neurology 09/2014; 263. DOI:10.1016/j.expneurol.2014.09.008 · 4.70 Impact Factor
  • Source
    Paul J. Trim · Adeline A. Lau · John J. Hopwood · Marten F. Snel
    [Show abstract] [Hide abstract]
    ABSTRACT: RATIONALEDetermination of genotype can be difficult, especially during the early stages of developing an animal model, e.g. when PCR primers are not yet available. An increase or decrease in specific metabolites can be used as a surrogate marker for genotype; for instance, in homozygous MPS IIIA mice heparan sulphate (HS) is increased. METHODSA simple method was developed for extracting and depolymerising HS from mouse toe tissue using methanolysis under acidic conditions. The sample was lyophilised and resuspended in methanolic HCl. The reaction products are desulphated disaccharides and readily analysable by liquid chromatography/tandem mass spectrometry (LC/MS/MS) in positive ion multiple reaction monitoring mode. Measurements were normalised to a spiked deuterated HS internal standard and to endogenous chondroitin sulphate (CS). RESULTSHS was measured in toe tissue taken from 30 mice in three groups of 10 (normal controls, MPS IIIA homozygotes and heterozygotes). A significant difference was observed between the MPS IIIA homozygotes and the other two groups, making it possible to identify mice with the MPS IIIA genotype based on the measurement of HS. Normalisation to CS was shown to correct for sample variability and reaction efficiency. CONCLUSIONS Analysis of toe tissue provides a simple and rapid way of determining a storage phenotype at 5 to 7 days of age. Significantly, this method does not require any additional samples to be taken from animals, as it utilises tissue that is a by-product of toe clipping, a method that is routinely used to permanently identify mice. Copyright © 2014 John Wiley & Sons, Ltd.
    Rapid Communications in Mass Spectrometry 04/2014; 28(8). DOI:10.1002/rcm.6861 · 2.25 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Lysosomal storage disorders are a large group of inherited metabolic conditions resulting from the deficiency of proteins involved in lysosomal catabolism, with resulting accumulation of substrates inside the cell. Two-thirds of these disorders are associated with a neurodegenerative phenotype and, although few therapeutic options are available to patients at present, clinical trials of several treatments including lysosomal enzyme replacement are underway. Although animal studies indicate the efficacy of pre-symptomatic treatment, it is largely unknown whether symptomatic disease-related pathology and functional deficits are reversible. To begin to address this, we used a naturally-occurring mouse model with Sanfilippo syndrome (mucopolysaccharidosis type IIIA) to examine the effectiveness of intracisternal cerebrospinal fluid enzyme replacement in early, mid- and symptomatic disease stage mice. We observed a disease-stage-dependent treatment effect, with the most significant reductions in primary and secondary substrate accumulation, astrogliosis and protein aggregate accumulation seen in mucopolysaccharidosis type IIIA mice treated very early in the disease course. Affected mice treated at a symptomatic age exhibited little change in these neuropathological markers in the time-frame of the study. Microgliosis was refractory to treatment regardless of the age at which treatment was instigated. Although longer-term studies are warranted, these findings indicate the importance of early intervention in this condition.
    European Journal of Neuroscience 04/2014; 39(12). DOI:10.1111/ejn.12557 · 3.18 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The premature stop codon mutations, Q70X and W402X, are the most common α-L-iduronidase gene (IDUA) mutations in mucopolysaccharidosis type I (MPS I) patients. Read-through drugs have been used to suppress premature stop codons, and this can potentially be used to treat patients who have this type of mutation. We examined the effects of aminoglycoside treatment on the IDUA mutations Q70X and W402X in cultured cells and show that 4,5-disubstituted aminoglycosides induced more read-through for the W402X mutation, while 4,6-disubstituted aminoglycosides promoted more read-through for the Q70X mutation: lividomycin (4,5-disubstituted) induced a 7.8-fold increase in α-L-iduronidase enzyme activity for the W402X mutation; NB54 (4,5-disubstituted) induced a 3.7 fold increase in the amount of α-L-iduronidase enzyme activity for the W402X mutation, but had less effect on the Q70X mutation, whereas gentamicin (4,6-disubstituted) had the reverse effect on read-through for both mutations. The predicted mRNA secondary structural changes for both mutations were markedly different, which may explain these different effects on read-through for these two premature stop codons.
    11/2013; 13. DOI:10.1007/8904_2013_270
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Sonic Hedgehog (Shh) signaling is crucial for growth, cell fate determination, and axonal guidance in the developing nervous system. Although the receptors Patched (Ptch1) and Smoothened (Smo) are required for Shh signaling, a number of distinct co-receptors contribute to these critical responses to Shh. Several membrane-embedded proteins such as Boc, Cdo, and Gas1 bind Shh and promote signaling. In addition, heparan sulfate proteoglycans (HSPGs) have also been implicated in the initiation of Shh responses. However, the attributes of HSPGs that function as co-receptors for Shh have not yet been defined. Here, we identify HSPGs containing a glypican 5 core protein and 2-O-sulfo-iduronic acid residues at the nonreducing ends of the glycans as co-receptors for Shh. These HSPG co-receptors are expressed by cerebellar granule cell precursors and promote Shh binding and signaling. At the subcellular level, these HSPG co-receptors are located adjacent to the primary cilia that act as Shh signaling organelles. Thus, Shh binds to HSPG co-receptors containing a glypican 5 core and 2-O-sulfo-iduronic acid to promote neural precursor proliferation.
    Journal of Biological Chemistry 07/2013; 288(36). DOI:10.1074/jbc.M112.438937 · 4.57 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Characteristic cardiac valve abnormalities and left ventricular hypertrophy are present in untreated patients with mucopolysaccharidosis type VI (MPS VI). Cardiac ultrasound was performed to investigate these findings in subjects during long-term enzyme replacement therapy (ERT) with recombi-nant human arylsulfatase B (rhASB, rhN-acetylgalactosamine 4-sulfatase, galsulfase, Naglazyme®). Studies were conducted in 54 subjects before ERT was begun and at specific intervals for up to 96 weeks of weekly infusions of rhASB at 1 mg/kg during phase 1/2, phase 2, and phase 3 trials of rhASB. At baseline, mitral and aortic valve obstruction was present and was significantly greater in those ≥12 years of age. Mild mitral and trace aortic regurgitation were present, the former being significantly greater in those <12 years. Left ventricular hy-pertrophy, with averaged z-scores ranging from 1.6–1. ≥12 years. After 96 weeks of ERT, ventricular septal hyper-trophy regressed in those <12 years. For those ≥12 years, septal hypertrophy was unchanged, and aortic regurgitation increased statistically but not physiologically. Obstructive gradients across mitral and aortic valves remained unchanged. The results suggest that long-term ERT is effective in reducing intraventricular septal hypertrophy and preventing progres-sion of cardiac valve abnormalities when administered to those <12 years of age.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Patients with some neurological lysosomal storage disorders (LSD) exhibit improved clinical signs following bone marrow transplantation (BMT). The failure of mucopolysaccharidosis (MPS) type IIIA patients and adult mice with the condition to respond to this treatment may relate to factors such as impaired migration of donor-derived cells into the brain, insufficient enzyme production and/or secretion by the donor-derived microglial cells, or the age at which treatment is initiated. To explore these possibilities, we treated neonatal MPS IIIA mice with whole unfractionated bone marrow and observed that nucleated blood cell reconstitution occurred to a similar degree in MPS IIIA mice receiving green fluorescent protein (GFP)-expressing normal (treatment group) or MPS IIIA-GFP marrow (control group) and normal mice receiving normal-GFP marrow (control group). Further, similar distribution patterns of GFP(+) normal or MPS IIIA donor-derived cells were observed throughout the MPS IIIA mouse brain. We demonstrate that N-sulfoglucosamine sulfohydrolase (SGSH), the enzyme deficient in MPS IIIA, is produced and secreted in a manner proportional to that of other lysosomal enzymes. However, despite this, overall brain SGSH activity was unchanged in MPS IIIA mice treated with normal marrow and the lysosomal storage burden in whole brain homogenates did not decrease, most likely due to donor-derived cells comprising <0.24% of total recipient brain cells in all groups. This suggests that the failure of MPS IIIA patients and mice to respond to BMT may occur as a result of insufficient donor-derived enzyme production and/or uptake by host brain cells.
    02/2013; 8:121-32. DOI:10.1007/8904_2012_169
  • [Show abstract] [Hide abstract]
    ABSTRACT: Mucopolysaccharidosis IIIA (MPS IIIA) is a lysosomal storage disorder caused by a deficiency in the activity of the lysosomal hydrolase, sulphamidase, an enzyme involved in the degradation of heparan sulphate. MPS IIIA patients exhibit progressive mental retardation and behavioural disturbance. While neuropathology is the major clinical problem in MPS IIIA patients, there is little understanding of how lysosomal storage generates this phenotype. As reduced neuronal communication can underlie cognitive deficiencies, we investigated whether the secretion of neurotransmitters is altered in MPS IIIA mice; utilising adrenal chromaffin cells, a classical model for studying secretion via exocytosis. MPS IIIA chromaffin cells displayed heparan sulphate storage and electron microscopy revealed large electron-lucent storage compartments. There were also increased numbers of large/elongated chromaffin granules, with a morphology that was similar to immature secretory granules. Carbon fibre amperometry illustrated a significant decrease in the number of exocytotic events for MPS IIIA, when compared to control chromaffin cells. However, there were no changes in the kinetics of release, the amount of catecholamine released per exocytotic event, or the amount of Ca(2+) entry upon stimulation. The increased number of large/elongated granules and reduced number of exocytotic events suggests that either the biogenesis and/or the cell surface docking and fusion potential of these vesicles is impaired in MPS IIIA. If this also occurs in central nervous system neurons, the reduction in neurotransmitter release could help to explain the development of neuropathology in MPS IIIA.
    Neuroscience 09/2012; 227. DOI:10.1016/j.neuroscience.2012.09.034 · 3.36 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Characteristic cardiac valve abnormalities and left ventricular hypertrophy are present in untreated patients with mucopolysaccharidosis type VI (MPS VI). Cardiac ultrasound was performed to investigate these findings in subjects during long-term enzyme replacement therapy (ERT) with recombinant human arylsulfatase B (rhASB, rhN-acetylgalactosamine 4-sulfatase, galsulfase, Naglazyme®). Studies were conducted in 54 subjects before ERT was begun and at specific intervals for up to 96 weeks of weekly infusions of rhASB at 1 mg/kg during phase 1/2, phase 2, and phase 3 trials of rhASB. At baseline, mitral and aortic valve obstruction was present and was significantly greater in those ≥12 years of age. Mild mitral and trace aortic regurgitation were present, the former being significantly greater in those <12 years. Left ventricular hypertrophy, with averaged z-scores ranging from 1.6-1.9 SD greater than normal, was present for ages both <12 and ≥12 years. After 96 weeks of ERT, ventricular septal hypertrophy regressed in those <12 years. For those ≥12 years, septal hypertrophy was unchanged, and aortic regurgitation increased statistically but not physiologically. Obstructive gradients across mitral and aortic valves remained unchanged. The results suggest that long-term ERT is effective in reducing intraventricular septal hypertrophy and preventing progression of cardiac valve abnormalities when administered to those <12 years of age.
    Journal of Inherited Metabolic Disease 06/2012; 36(2). DOI:10.1007/s10545-012-9481-2 · 3.37 Impact Factor
  • Source
    G Dawson · M Fuller · K M Helmsley · J J Hopwood
    [Show abstract] [Hide abstract]
    ABSTRACT: Allogenic stem cell transplantation can reduce lysosomal storage of heparan sulfate-derived oligosaccharides by up to 27 % in Sanfilippo MPS3a brain, but does not reduce the abnormal storage of sialolactosylceramide (G(M3)) or improve neurological symptoms, suggesting that ganglioside storage is in a non-lysosomal compartment. To investigate this further we isolated the Triton X100-insoluble at 4 °C, lipid raft (LR) fraction from a sucrose-density gradient from cerebral hemispheres of a 7 month old mouse model of Sanfilippo MPS3a and age-matched control mouse brain. HPLC/MS/MS analysis revealed the expected enrichment of normal complex gangliosides, ceramides, galatosylceramides and sphingomyelin enrichment in this LR fraction. The abnormal HS-derived oligosaccharide storage material was in the Triton X100-soluble at 4 °C fractions (8-12),whereas both GM3 and sialo[GalNAc]lactosylceramide (GM2) were found exclusively in the LR fraction (fractions 3 and 4) and were >90 % C18:0 fatty acid, suggesting a neuronal origin. Further analysis also revealed a >threefold increase in the late-endosome marker bis (monoacylglycerol) phosphate (>70 % as C22:6/22:6-BMP) in non-LR fractions 8-12 whereas different forms of the proposed BMP precursor, phosphatidylglycerol (PG) were in both LR and non-LR fractions and were less elevated in MPS3a brain. Thus heparan sulfate-derived oligosaccharide storage is associated with abnormal lipid accumulation in both lysosomal (BMP) and non-lysosomal (GM3 and GM2) compartments.
    Neurochemical Research 04/2012; 37(6):1372-80. DOI:10.1007/s11064-012-0761-x · 2.59 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Mucopolysaccharidosis (MPS) VI is due to a deficiency in the activity of N-acetylgalactosamine 4-sulfatase (4S), also known as arylsulfatase B. Previously, retroviral vector (RV)-mediated neonatal gene therapy reduced the clinical manifestations of MPS I and MPS VII in mice and dogs. However, sulfatases require post-translational modification by sulfatase-modifying factors. MPS VI cats were injected intravenously (i.v.) with a gamma RV-expressing feline 4S, resulting in 5 ± 3 copies of RV per 100 cells in liver. Liver and serum 4S activity were 1,450 ± 1,720 U/mg (26-fold normal) and 107 ± 60 U/ml (13-fold normal), respectively, and were directly proportional to the liver 4S protein levels for individual cats. This study suggests that sulfatase-modifying factor (SUMF) activity in liver was sufficient to result in active enzyme despite overexpression of 4S. RV-treated MPS VI cats achieved higher body weights and longer appendicular skeleton lengths, had reduced articular cartilage erosion, and reduced aortic valve thickening and aortic dilatation compared with untreated MPS VI cats, although cervical vertebral bone lengths were not improved. This demonstrates that therapeutic expression of a functional sulfatase protein can be achieved with neonatal gene therapy using a gamma RV, but some aspects of bone disease remain difficult to treat.
    Molecular Therapy 03/2012; 20(5):898-907. DOI:10.1038/mt.2012.9 · 6.23 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Glycogen storage in the α-glucosidase knockout((6neo/6neo)) mouse recapitulates the biochemical defect that occurs in the human condition; as such, this mouse serves as a model for the inherited metabolic deficiency of lysosomal acid α-glucosidase known as Pompe disease. Although this model has been widely used for the assessment of therapies, the time course of glycogen accumulation that occurs as untreated Pompe mice age has not been reported. To address this, we developed a quantitative method involving amyloglucosidase digestion of glycogen and quantification of the resulting free glucose by liquid chromatography/electrospray ionization-tandem mass spectrometry. The method was sensitive enough to measure as little as 0.1 μg of glycogen in tissue extracts with intra- and interassay coefficients of variation of less than 12%. Quantification of glycogen in tissues from Pompe mice from birth to 26 weeks of age showed that, in addition to the accumulation of glycogen in the heart and skeletal muscle, glycogen also progressively accumulated in the brain, diaphragm, and skin. Glycogen storage was also evident at birth in these tissues. This method may be particularly useful for longitudinal assessment of glycogen reduction in response to experimental therapies being trialed in this model.
    Analytical Biochemistry 02/2012; 421(2):759-63. DOI:10.1016/j.ab.2011.12.026 · 2.22 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Mucopolysaccharidosis VI (MPS-VI) is caused by a deficiency in N-acetylgalactosamine-4-sulfatase activity, resulting in lysosomal accumulation of partially degraded glycosaminoglycans (GAGs). Compressive myelopathy in early-onset MPS-VI patients has been partly attributed to thickening of the dura mater following engorgement with GAG. In this study, we therefore tested whether the dural abnormalities could be prevented in a feline model of the disorder. All intrathecal injections (IT-INJs) were well tolerated. MPS-VI cats treated with IT-INJ of recombinant human N-acetylgalactosamine-4-sulfatase (rhASB) exhibited reduced vacuolation in the dural fibroblasts, diminished levels of sulfated-N-acetylhexosamine (HNAc(+S)) in the cerebrospinal fluid (CSF) and no hind-limb paresis. Serum anti-rhASB antibodies remained low in MPS-VI cats treated with intravenous enzyme replacement therapy (IV-ERT) and increased slightly in normal cats treated with IT-INJ of rhASB alone. Anti-rhASB antibodies in CSF remained undetectable. These data indicate that repeated IT-INJ of rhASB can safely prevent GAG storage in MPS-VI dura. Cats were assigned to three groups: (i) receiving weekly IV-ERT of rhASB from birth plus six monthly IT-INJs of rhASB from age 2 months; (ii) receiving six monthly IT-INJs of vehicle; or (iii) untreated. Additional normal cats received five fortnightly IT-INJs of rhASB or vehicle alone.
    Pediatric Research 01/2012; 71(1):39-45. DOI:10.1038/pr.2011.13 · 2.31 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: To investigate and characterise an inborn error of metabolism in a dog with skeletal and ocular abnormalities. A 2.5-year-old small male Miniature Poodle-like dog was presented with gross joint laxity and bilateral corneal opacities. Clinical examination was augmented by routine haematology, serum chemistry, radiographs, pathology, enzymology and molecular genetic studies. Euthanasia was requested when the dog was 3 years of age because of progressively decreasing quality of life. Radiology revealed generalised epiphyseal dysplasia, malformed vertebral bodies, luxation/subluxation of appendicular and lumbosacral joints with hypoplasia of the odontoid process and hyoid apparatus. These clinical and radiographic findings, together with a positive urinary Berry spot test for mucopolysaccharides, and metachromatic granules in leucocytes, were indicative of a mucopolysaccharidosis (MPS), a lysosomal storage disease. Histological lesions included vacuolation of stromal cells of the cornea, fibroblasts, chondrocytes, macrophages and renal cells. The brain was essentially normal except for moderate secondary Wallerian-type degeneration in motor and sensory tracts of the hind brain. Dermatan sulphate-uria was present and enzymology revealed negligible activity of N-acetylgalactosamine-4-sulphatase, also known as arylsulphatase B, in cultured fibroblasts and liver tissue. A novel homozygous 22 base pair (bp) deletion in exon 1 of this enzyme's gene was identified (c.103_124del), which caused aframe-shift and subsequent premature stop codon. The "Wisdom pure breed-mixed breed" test reported the dog as a cross between a Miniature and Toy Poodle. The clinicopathological features are similar to those of MPS type VI as previously described in dogs, cats and other species, and this clinical diagnosis was confirmed by enzymology and molecular genetic studies. This is an autosomal recessively inherited lysosomal storage disease. The prevalence of MPS VI in Miniature or Toy Poodles in New Zealand and elsewhere is currently unknown. Due to the congenital nature of the disorder, malformed pups may be subject to euthanasia without investigation and the potential genetic problem in the breed may not be fully recognised. The establishment of a molecular genetic test now permits screening for this mutation as a basis to an informed breeding policy.
    New Zealand veterinary journal 11/2011; 60(3):183-8. DOI:10.1080/00480169.2011.642791 · 1.26 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Mucopolysaccharidosis type IIIA (MPS-IIIA) is a severe neurodegenerative lysosomal storage disorder caused by a deficiency of N-sulfoglucosamine sulfohydrolase (SGSH) activity with subsequent accumulation of partially-degraded heparan sulfate and other glycolipids. In this study, we have evaluated a gene therapy approach using a helper-dependent canine adenovirus vector that expresses human SGSH as a means of delivering sustained transgene expression to the brain. Initial testing in a mixed neural cell culture model demonstrated that the vector could significantly increase SGSH activity in transduced cells, resulting in near-normalization of heparan sulfate-derived fragments. While administration of vector by direct injection into the brain of adult MPS-IIIA mice enabled transgene expression for at least 8.5 months post-treatment, it was only in discrete areas of brain. Heparan sulfate storage was reduced in some regions following treatment, however there was no improvement in secondary neuropathological changes. These data demonstrate that helper-dependent canine adenovirus vectors are capable of neural transduction and mediate long-term transgene expression, but increased SGSH expression throughout the brain is likely to be required in order to effectively treat all aspects of the MPS-IIIA phenotype.
    Gene 09/2011; 491(1):53-7. DOI:10.1016/j.gene.2011.09.004 · 2.14 Impact Factor

Publication Stats

11k Citations
1,720.68 Total Impact Points


  • 2014–2015
    • South Australian Health and Medical Research Institute
      Adelaide Hills, South Australia, Australia
  • 2013
    • University of South Australia 
      • School of Pharmacy and Medical Sciences
      Tarndarnya, South Australia, Australia
  • 2002–2013
    • University of Adelaide
      • Discipline of Paediatrics
      Tarndarnya, South Australia, Australia
    • Hacettepe University
      • Department of Medical Biology
      Engüri, Ankara, Turkey
  • 1993–2011
    • Women`s and Children`s Hospital
      Tarndarnya, South Australia, Australia
    • University of Zurich
      Zürich, Zurich, Switzerland
    • University of Greifswald
      Griefswald, Mecklenburg-Vorpommern, Germany
  • 2008
    • Institut Marqués, Spain, Barcelona
      Barcino, Catalonia, Spain
  • 2004
    • Children's Hospital & Research Center Oakland
      Oakland, California, United States
  • 1999
    • Tufts University
      Бостон, Georgia, United States
    • University of Melbourne
      • Department of Biochemistry and Molecular Biology
      Melbourne, Victoria, Australia
  • 1996
    • Lund University
      Lund, Skåne, Sweden
  • 1982–1995
    • Royal Adelaide Hospital
      • Department of Chemical Pathology
      Tarndarnya, South Australia, Australia
  • 1991
    • Universität Ulm
      Ulm, Baden-Württemberg, Germany
  • 1989
    • Johns Hopkins University
      • Department of Pediatrics
      Baltimore, Maryland, United States
  • 1983
    • SickKids
      Toronto, Ontario, Canada
  • 1975
    • University of Chicago
      • Pritzker School of Medicine
      Chicago, Illinois, United States
  • 1974
    • Monash University (Australia)
      Melbourne, Victoria, Australia