Biomedical subjects

Reuben Matalon

Publications and source records attributed to Reuben Matalon.

34 records · Page 2Linked to original sources

PubMed2003

Adeno-associated virus-mediated aspartoacylase gene transfer to the brain of knockout mouse for canavan disease.

Canavan disease (CD) is an autosomal recessive leukodystrophy caused by deficiency of aspartoacylase (ASPA). Deficiency of ASPA leads to elevation of N-acetyl-L-aspartic acid (NAA) in the brain and urine. To explore the feasibility of gene transfer to replace ASPA in CD, we generated a knockout mouse and constructed an AAV vector that encodes human ASPA cDNA (hASPA) followed by green fluorescent protein (GFP) after an intraribosomal entry site. We injected CD mice with rAAV-hASPA-GFP in the striatum and thalamus or injected rAAV-GFP identically into control animals. Three to five months after the injection, we determined the presence of ASPA in the CD mouse brain by ASPA activity assay, GFP expression, and Western blot analysis. While rAAV-GFP-injected animals displayed undetectable levels of ASPA, all detection methods revealed significant ASPA levels in rAAV-hASPA-GFP-injected CD mice. We evaluated the functional effects of rAAV-hASPA-GFP-mediated ASPA expression by standard histological methods, magnetic resonance spectroscopy (MRS) for in vivo NAA levels, and magnetic resonance imaging of CD mice. rAAV-hASPA-injected animals displayed a remarkable lack of spongiform degeneration in the thalamus. However, pathology in sites unrelated to the injected areas showed no improvement in histopathology. The improvement in thalamic neuropathology was also detectable via in vivo MRI. MRS revealed that in vivo NAA levels were also reduced. These data indicate that rAAV-mediated ASPA delivery may be an interesting avenue for the treatment of CD.

Amidohydrolases↗

PubMed2003

High levels of orexin A in the brain of the mouse model for phenylketonuria: possible role of orexin A in hyperactivity seen in children with PKU.

Phenylketonuria (PKU) is a metabolic disorder caused by phenylalanine hydroxylase deficiency leading to increased levels of phenylalanine in the brain. Hyperactivity is reportedly induced by a high level of orexin A, and therefore orexin A content was studied in the PKU mice. Hypothalamus and brain stem had higher levels of orexin A compared to cerebrum and cerebellum both in wild type and PKU mice brains as observed by radioimmunoassay method. Interestingly, all these regions of the brain in PKU mouse showed a higher level of orexin A compared to the wild type. Heart and plasma also had higher levels of orexin A in PKU compared to the wild type. Immunohistochemical analysis revealed an increased number of orexin A-stained cells in the brain and heart of PKU mouse compared to the wild type. This is the first report of increased level of orexin in the PKU mouse brain. Hyperactivity is commonly observed in children with PKU; thus these findings suggest that orexin A is a contributing factor for the hyperactivity.

Animals↗

PubMed2003

Molecular basis of Canavan's disease: from human to mouse.

Canavan's disease is an autosomal recessive disorder caused by aspartoacylase deficiency. The deficiency of aspartoacylase leads to increased concentration of N-acetylaspartic acid in brain and body fluids. The failure to hydrolyze N-acetylaspartic acid causes disruption of myelin, resulting in spongy degeneration of the white matter of the brain. The clinical features of the disease are hypotonia in early life, which changes to spasticity, macrocephaly, head lag, and progressive severe mental retardation. Although Canavan's disease is panethnic, it is most prevalent in the Ashkenazi Jewish population. Research at the molecular level led to the cloning of the gene for aspartoacylase and development of a knockout mouse for Canavan's disease. These developments have afforded new tools for research in the attempts to understand the pathophysiology of Canavan's disease, design new therapies, and explore methods for gene transfer to the central nervous system.

Amidohydrolases↗

PubMed2003

Metabolic changes in the knockout mouse for Canavan's disease: implications for patients with Canavan's disease.

Canavan's disease is an autosomal recessive disorder caused by aspartoacylase deficiency, which leads to accumulation of N-acetylaspartic acid in the brain and blood and an elevated level of N-acetylaspartic acid in the urine. The brain of patients with Canavan's disease shows spongy degeneration. How the enzyme deficiency and elevated N-acetylaspartic acid cause the pathophysiology observed in Canavan's disease is not obvious. The creation of a knockout mouse for Canavan's disease is being used as a tool to investigate metabolic pathways in the mouse and correlate them with the patients with Canavan's disease. The level of glutamate is lower in the knockout mouse brain than in the wild-type mouse brain, similar to what we have found in children with Canavan's disease, and so are the levels of gamma-aminobutyric acid (GABA). The level of aspartate is higher in the Canavan's disease mouse brain. The activity of aspartate aminotransferase, an enzyme involved in the malate-aspartate shuttle, is lower in the Canavan's disease mouse brain. The lower weight of the Canavan's disease mouse was in direct proportion to low total-body fat and bone mineral density. These changes might be similar to what is seen in patients with Canavan's disease and could have therapeutic implications.

Animals↗

PubMed2003

Mild elevation of N-acetylaspartic acid and macrocephaly: diagnostic problem.

Patients with slightly increased excretion of N-acetylaspartic acid in urine, together with macrocephaly, present a dignostic dilemma for Canavan's disease. We describe a 13-year-old male patient with macrocephaly, mild developmental delay, increased signal intensity in the basal ganglia bilaterally, partial cortical blindness, and retinitis pigmentosa. Although the clinical course and magnetic resonance imaging findings did not resemble typical Canavan's disease, N-acetylaspartic acid excretion in the patient's urine was slightly elevated, 99.90 +/- 4.00 microg/mg creatinine, whereas the normal control range was < 83 microg/mg creatinine. Cultured skin fibroblasts from the patient showed no aspartoacylase activity. Cloning of genomic DNA isolated from the patient's fibroblasts showed an intronic mutation, specifically deletion of -2A and -3C at the acceptor site of exon 3 and disrupting the normal splicing of the gene. A second mutation was found in exon 6, 863 A-->G in aspartoacylase complementary DNA, causing a tyrosine-to-cysteine (Y288C) amino acid substitution. Expression of the mutation on exon 6 showed normal aspartoacylase activity. These data suggest that expression of the mutation may help to understand the enzyme defect in a patient with slightly increased N-acetylaspartic acid excretion.

Adolescent↗

PubMed2003

Research design, organization, and sample characteristics of the Maternal PKU Collaborative Study.

OBJECTIVE: The Maternal PKU Collaborative Study (MPKUCS) was initiated in 1984 by the National Institute of Child Health and Human Development (NICHD). The purpose was to assess the efficacy of dietary restriction of phenylalanine in reducing morbidity in offspring of women with hyperphenylalaninemia (HPA). A contract was awarded to Childrens Hospital Los Angeles as the Coordinating Center to provide implementation of the research protocol, data collection, and analysis. METHODS: The Study included four regional contributing centers: Childrens Hospital Los Angeles (Western Region), Boston Children's Hospital (Northeast Region), University of Illinois (Midwest Region), and University of Texas Medical Branch, Galveston (Southeast Region). Within each region, many participating clinics were responsible for obstetric care, treatment, and monitoring protocols. In 1985, Canada joined the MPKUCS, and in 1992, Germany entered. They were selected because they provided dietary supplies and strong professional services. Acquisition began in 1984 and ended in October 1995. The study included 574 pregnancies in women with HPA and 100 control subjects matched on age, race, parity, and weeks of gestation. The sample included women with blood phenylalanine values >240 micromol/L, 66% of whom had classical PKU, 22% had atypical PKU, and 12% had mild HPA. Informed consents were obtained on all participants. The women ranged in age from 15 to 36 years of age, with a mean age at conception of 23 years. Teenage pregnancies accounted for 19%. Seventy-five percent graduated from high school. Offspring included 416 newborns, 317 of whom were evaluated at 4 years of age and 289 at 6 to 7 years. Follow-up involved medical, nutritional, psychosocial, and psychological assessments. CONCLUSION: Women with PKU treated before conception and in control of their blood phenylalanine levels between 120 and 360 micromol/L (2-6 mg) exhibited normal pregnancies and neonatal outcome. Surprisingly, women who achieved control in the recommended range by 8 weeks of pregnancy also had a normal fetal outcome.

Adolescent↗

PubMed2003

The Maternal Phenylketonuria International Study: 1984-2002.

OBJECTIVE: The purpose of this report is to review the obstetric medical, psychological, and nutritional aspects and outcome of the women and offspring enrolled in the Maternal Phenylketonuria Study, which was established to assess the efficacy of a phenylalanine (Phe)-restricted diet in preventing the morbidity associated with this disorder. METHODS: A total of 382 women with hyperphenylalaninemia (HPA) were enrolled in the study and completed 572 pregnancies. Outcome measures were analyzed with chi2, Fisher exact text, analysis of variance, t test, Wilcoxon nonparametric test, and multiple logistic regression. Outcome measures were stratified according to maternal HPA classification and the time when dietary control was achieved. RESULTS: Optimal birth outcomes occurred when maternal blood Phe levels between 120 and 360 micromol/L were achieved by 8 to 10 weeks of gestation and maintained throughout pregnancy (trimester averages of 600 micromol/L). Mothers with mild HPA achieved similar birth outcomes as mothers who were in control preconceptually and those in control by 8 to 10 weeks of pregnancy. CONCLUSIONS: Before conception, counseling and early entrance into a prenatal care program is essential in achieving optimal fetal outcome in women with HPA. The achievement of pre- and periconceptional dietary control with a Phe-restricted diet significantly decreased morbidity in the offspring of women with HPA.

Analysis of Variance↗

PubMed2003

Impact of the phenylalanine hydroxylase gene on maternal phenylketonuria outcome.

OBJECTIVE: The aim of the present study was to examine to what extent maternal and offspring phenylalanine hydroxylase (PAH) genotypes in conjunction with maternal IQ and dietary control during pregnancy are related to cognitive development in offspring of women with phenylketonuria (PKU). METHODS: PAH gene mutations were determined in 196 maternal PKU subjects and their offspring. The women were grouped according to PAH genotype, which predicts the metabolic phenotype (severe PKU, mild PKU, and mild hyperphenylalaninemia [MHP]). IQ was determined in both the mothers (Wechsler Adult Intelligence Scale-Revised at >18 years) and their children (Wechsler Intelligence Scale for Children-Revised at > or = 6-7 years of age). RESULTS: According to PAH genotypes, 62% of the women exhibited severe PKU, 19% exhibited mild PKU, and 19% exhibited MHP. Maternal IQ increased, and the assigned phenylalanine (Phe) levels decreased with decreasing severity of PAH genotype. In offspring of mild maternal PKU, multiple regression analysis showed offspring IQ to be significantly related to maternal IQ but not to Phe exposure during pregnancy, which was <750 micromol/L in all cases of mild PKU. In offspring of mothers with severe PKU and average Phe exposure during pregnancy of 360 to 750 micromol/L, multiple regression analysis revealed both maternal IQ and Phe exposure to be significant predictors of offspring IQ. When average Phe exposure was <360 micromol/L, cognitive development was normal (mean IQ: 105), whereas an average Phe exposure of >750 micromol/L severely depressed offspring IQ (mean IQ: 56) in this group regardless of maternal IQ. It could not be documented that the offspring PAH genotype affects cognitive development. CONCLUSION: Female individuals with severe PKU should be offered a diet for a lifetime. If good metabolic control is established, then women with PKU will have children with IQ scores that are not influenced by their disease.

Analysis of Variance↗

PubMed2003

Pregnancy experiences in the woman with mild hyperphenylalaninemia.

OBJECTIVE: A major issue in maternal phenylketonuria (MPKU) has been whether maternal non-PKU mild hyperphenylalaninemia (MHP) is teratogenic. Such untreated pregnancies and their outcomes are presented on this report. METHODS: Enrolled pregnancies in which the untreated prepregnancy assigned phenylalanine level (APL) was no more than 600 micro mol/L were included in the Maternal PKU Collaborative Study and were followed according to protocol. RESULTS: Forty-eight enrolled women with non-PKU MHP had mean APL 408 +/- 114 micromol/L. They had a total of 58 pregnancies that resulted in live births. Fifty were untreated. Maternal phenylalanine (Phe) levels in the untreated pregnancies decreased during pregnancy for average Phe exposure of 270 +/- 84 micromol/L, virtually identical to the level of 269 +/- 136 micromol/L in the 8 treated pregnancies. Birth measurements in the 50 offspring from untreated pregnancies were within normal limits with z scores of -0.25 for weight, 0.28 for length, and -0.63 for head circumference, although birth head circumference was negatively correlated with maternal APL (r = -0.30). Only 1 offspring had congenital heart disease. Offspring IQ was 102 +/- 15 compared with 96 +/- 14 in the mothers with untreated pregnancies and with 109 +/- 21 in control offspring. CONCLUSION: Maternal non-PKU MHP no more than 600 micromol/L does not require dietary therapy. The naturally lower Phe level during pregnancy seems to protect against teratogenesis.

Birth Weight↗

PubMed2003

Future role of large neutral amino acids in transport of phenylalanine into the brain.

OBJECTIVE: The treatment of phenylketonuria (PKU) in children and adults has been difficult because of erosion of dietary adherence, leading to poor school performance, impairment of executive functioning, loss of IQ, and deterioration of white matter in the brain. Mutant PKU mice produced by exposure to N-ethyl-N'-nitrosourea (ENU) were used to examine the effect of large neutral amino acid (LNAA) supplementation on brain and blood phenylalanine (Phe). METHODS: Mice with PKU, genotype ENU 2/2 with features of classical PKU, were supplemented with LNAA while on a normal diet. Two dosages of LNAA were given 0.5 g/kg and 1.0 g/kg by gavage. Blood Phe was determined in the experimental, control, and sham-treated mice. Brain Phe was determined by magnetic resonance spectroscopy after perchloric acid extraction. Branched-chain amino acid transferase (BCAT) was determined in brain as a marker for energy metabolism. RESULTS: Blood Phe was reduced in the LNAA-treated mice by an average of 15% (0.5 g/kg) and 50% (1.0 g/kg) in 48 hours. There was a sustained decrease in the blood Phe levels over a 6-week trial. The untreated mice and sham-treated mice maintained high blood Phe throughout the experiments. Brain Phe level determined by magnetic resonance spectroscopy showed a decline of 46% after the LNAA treatment. BCAT levels were lower (33%) in the ENU 2/2 mice compared with wild-type. The BCAT normalized in mice with PKU that were treated with LNAA. CONCLUSION: The results suggest that giving LNAA lowered brain and blood Phe levels in mice with PKU. Energy metabolism generated from BCAT also improved in mice with PKU after treatment with LNAA. Data from the mice suggest that LNAA should be considered among the strategies to treat PKU in humans.

Amino Acids, Neutral↗

PubMed2002

DOOR syndrome: deficiency of E1 component of the 2-oxoglutarate dehydrogenase complex.

Four patients from three families with the clinical features of DOOR syndrome (onycho-osteodystrophy, dystrophic thumbs, sensorineural deafness, and increased urinary levels of 2-oxoglutarate) are the subjects of this report. Our report deals with the autosomal recessive form of the disease, wherein the activity of 2-oxoglutarate decarboxylase (E1(0)) in fibroblasts and white blood cells of the patients is decreased. The activity of E1(0) in all patients' fibroblasts and white blood cells was significantly lower compared to the controls. This study demonstrates for the first time that E1(0) deficiency is an important biochemical marker for the autosomal recessive form of DOOR syndrome.

Abnormalities, Multiple↗

PubMed2002

Canavan disease prenatal diagnosis and genetic counseling.

Canavan disease is a severe leukodystrophy more common among Ashkenazi Jews. The enzyme defect, apartoacylase, has been identified, and the gene cloned. Only two mutations account for over 98% of all Jewish alleles with Canavan disease. The carrier frequency among healthy Jews is 1:37-58. Carrier detection and prenatal diagnosis can be accurately carried out using molecular analysis. When mutations are unknown, analysis of amniotic fluid for NAA using stable isotope dilution technique can be used for prenatal diagnosis.

Canavan Disease↗

PubMed2002

Founder mutation R245H of Sanfilippo syndrome type A in the Cayman Islands.

Sanfilippo A syndrome is an autosomal recessive lysosomal storage disease. This disease was reported in the Cayman Islands population with carrier frequency of 1/7 to 1/10 in the West Bay district of Grand Cayman. The carrier testing of Sanfilippo A disease for families at risk was carried out using the thermal characteristics of sulfamidase activity. In the present study, a search for mutations in the sulfamidase gene in an index family was performed. In addition, 77 individuals, relatives of children with Sanfilippo A syndrome, were also studied by single-strand conformation polymorphism (SSCP), restriction fragment-length polymorphism (RFLP) analyses, and sequencing. A single mutation, G746A (R245H), was found in the family, with the patient being homozygous and both parents and 1 of the 3 siblings being carriers. Among the 77 family members of the patient with Sanfilippo syndrome, the same mutation was found among carriers of the disease. The finding of a single mutation supports the idea of a founder effect, which facilitates accurate carrier identification of Sanfilippo A syndrome in the population of Cayman Islands.

Amino Acid Substitution↗

PubMedDate not supplied

Aspartoacylase gene knockout in the mouse: impact on reproduction.

Canavan disease (CD) is an autosomal recessive disorder caused by aspartoacylase (ASPA) gene mutations resulting enzyme deficiency. The homozygous knockout mouse for CD showed symptoms similar observed in patients with CD. Canavan disease leads to early death. Therefore, a role of ASPA in reproduction was investigated using the mouse model for CD. Homozygous (KO/KO) pups, produced by mating female heterozygous (KO/+) mouse with KO/+ males had approximately 12% death incidence rates in the first 2 months of life. KO/KO mothers mated with KO/+ males showed fetal death. KO/KO mothers produced fewer offspring compared to KO/+ mothers. These data suggest that ASPA is necessary for normal reproduction and postnatal survival.

Amidohydrolases↗

PubMedDate not supplied

Canavan disease: a monogenic trait with complex genomic interaction.

Canavan disease (CD) is an inherited leukodystrophy, caused by aspartoacylase (ASPA) deficiency, and accumulation of N-acetylaspartic acid (NAA) in the brain. The gene for ASPA has been cloned and more than 40 mutations have been described, with two founder mutations among Ashkenazi Jewish patients. Screening of Ashkenazi Jews for these two common mutations revealed a high carrier frequency, approximately 1/40, so that programs for carrier testing are currently in practice. The enzyme deficiency in CD interferes with the normal hydrolysis of NAA, which results in disruption of myelin and spongy degeneration of the white matter of the brain. The clinical features of the disease are macrocephaly, head lag, progressive severe mental retardation, and hypotonia in early life, which later changes to spasticity. A knockout mouse for CD has been generated, and used to study the pathophysiological basis for CD. Findings from the knockout mouse indicate that this monogenic trait leads to a series of genomic interaction in the brain. Changes include low levels of glutamate and GABA. Microarray expression analysis showed low level of expression of GABA-A receptor (GABRA6) and glutamate transporter (EAAT4). The gene Spi2, a gene involved in apoptosis and cell death, showed high level of expression. Such complexity of gene interaction results in the phenotype, the proteome, with spongy degeneration of the brain and neurological impairment of the mouse, similar to the human counterpart. Aspartoacylase gene transfer trial in the mouse brain using adenoassociated virus (AAV) as a vector are encouraging showing improved myelination and decrease in spongy degeneration in the area of the injection and also beyond that site.

Amidohydrolases↗

PubMedDate not supplied

Biopterin responsive phenylalanine hydroxylase deficiency.

PURPOSE: Phenylketonuria (PKU) is an autosomal recessive disorder caused by mutations in the phenylalanine hydroxylase (PAH) gene. There have been more than 400 mutations identified in the PAH gene leading to variable degrees of deficiency in PAH activity, and consequently a wide spectrum of clinical severity. A pilot study was undertaken to examine the response to 6-R-l-erythro-5,6,7,8-tetrahydrobiopterin (BH4) in patients with atypical and classical PKU. METHODS: PAH gene mutation analysis was performed using denaturing gradient gel electrophoresis and gene sequencing. Patients with classical, atypical, or mild PKU were orally given BH4 10 mg/kg. Blood phenylalanine and tyrosine levels were determined using tandem MS/MS at 0 hours, 4 hours, 8 hours, and 24 hours intervals. RESULTS: Thirty-six patients were given a single oral dose of 10 mg/kg of BH4. Twenty one patients (58.33%) responded with a decrease in blood phenylalanine level. Of the patients that responded, 12 were classical, 7 atypical, and 2 mild. The mean decline in blood phenylalanine at 24 hours was > 30% of baseline. There were 15 patients who did not respond to the BH4 challenge, 14 of those had classical and one had atypical PKU. Mapping the mutations that responded to BH4 on the PAH enzyme showed that mutations were in the catalytic, regulatory, oligomerization, and BH4 binding domains. Five patients responding to BH4 had mutations not previously identified. CONCLUSION: The data presented suggest higher than anticipated number of PKU mutations respond to BH4, and such mutations are on all the domains of PAH.

Administration, Oral↗