Cancer cells hijack and remodel existing metabolic pathways for their benefit. Argininosuccinate synthase (ASS1) is a urea cycle enzyme that is essential in the conversion of nitrogen from ammonia and aspartate to urea. A decrease in... more
Cancer cells hijack and remodel existing metabolic pathways for their benefit. Argininosuccinate synthase (ASS1) is a urea cycle enzyme that is essential in the conversion of nitrogen from ammonia and aspartate to urea. A decrease in nitrogen flux through ASS1 in the liver causes the urea cycle disorder citrullinaemia. In contrast to the well-studied consequences of loss of ASS1 activity on ureagenesis, the purpose of its somatic silencing in multiple cancers is largely unknown. Here we show that decreased activity of ASS1 in cancers supports proliferation by facilitating pyrimidine synthesis via CAD (carbamoyl-phosphate synthase 2, aspartate transcarbamylase, and dihydroorotase complex) activation. Our studies were initiated by delineating the consequences of loss of ASS1 activity in humans with two types of citrullinaemia. We find that in citrullinaemia type I (CTLN I), which is caused by deficiency of ASS1, there is increased pyrimidine synthesis and proliferation compared with citrullinaemia type II (CTLN II), in which there is decreased substrate availability for ASS1 caused by deficiency of the aspartate transporter citrin. Building on these results, we demonstrate that ASS1 deficiency in cancer increases cytosolic aspartate levels, which increases CAD activation by upregulating its substrate availability and by increasing its phosphorylation by S6K1 through the mammalian target of rapamycin (mTOR) pathway. Decreasing CAD activity by blocking citrin, the mTOR signalling, or pyrimidine synthesis decreases proliferation and thus may serve as a therapeutic strategy in multiple cancers where ASS1 is downregulated. Our results demonstrate that ASS1 downregulation is a novel mechanism supporting cancerous proliferation, and they provide a metabolic link between the urea cycle enzymes and pyrimidine synthesis.
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The duodenal string test capsule is a cheap and simple device used for sampling the contents of the upper gastrointestinal tract. Its major applications in pediatrics are in diagnosis of enteric parasitic infestations, confirmation of... more
The duodenal string test capsule is a cheap and simple device used for sampling the contents of the upper gastrointestinal tract. Its major applications in pediatrics are in diagnosis of enteric parasitic infestations, confirmation of contaminated small-bowel syndrome, diagnosis of Salmonella infection, and assessment of neonatal cholestasis. Pediatricians should be aware of this invaluable diagnostic aid.
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A pseudocyst of the pancreas in a 6-year-old girl persisted for 2 months despite bowel rest and nutritional support. Following percutaneous introduction of a catheter into the cyst under ultrasound guidance and external catheter drainage... more
A pseudocyst of the pancreas in a 6-year-old girl persisted for 2 months despite bowel rest and nutritional support. Following percutaneous introduction of a catheter into the cyst under ultrasound guidance and external catheter drainage for 11 days, the pseudocyst resolved completely and permanently. Nonoperative percutaneous techniques for drainage of pancreatic pseudocysts in children may be an effective alternative to surgical intervention.
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L-2-hydroxyglutaric aciduria (L-2-HGA) is a rare inherited autosomal recessive neurometabolic disorder caused by mutations in the gene encoding L-2-hydroxyglutarate dehydrogenase. An assay to evaluate L-2-hydroxyglutarate dehydrogenase... more
L-2-hydroxyglutaric aciduria (L-2-HGA) is a rare inherited autosomal recessive neurometabolic disorder caused by mutations in the gene encoding L-2-hydroxyglutarate dehydrogenase. An assay to evaluate L-2-hydroxyglutarate dehydrogenase (L-2-HGDH) activity in fibroblast, lymphoblast and/or lymphocyte lysates has hitherto been unavailable. We developed an L-2-HGDH enzyme assay in cell lysates based on the conversion of stable-isotope-labelled L-2-hydroxyglutarate to 2-ketoglutarate, which is converted into L-glutamate in situ. The formation of stable isotope labelled L-glutamate is therefore a direct measure of L-2-HGDH activity, and this product is detected by liquid chromatography-tandem mass spectrometry. A deficiency of L-2-HGDH activity was detected in cell lysates from 15 out of 15 L-2-HGA patients. Therefore, this specific assay confirmed the diagnosis unambiguously affirming the relationship between molecular and biochemical observations. Residual activity was detected in cells derived from one L-2-HGA patient. The L-2-HGDH assay will be valuable for examining in vitro riboflavin/FAD therapy to rescue L-2-HGDH activity.
Research Interests: Genetics, Nutrition, Research Design, Glutamate, Humans, and 19 moreStable Isotope, Calibration, Animals, Cell, Tandem Mass Spectrometry, High Performance Liquid Chromatography, Enzyme, Implementation, Clinical Sciences, High Pressure Liquid Chromatography, Rats, Liquid Chromatography, Deficiency, Assay, Lymphocytes, Human Fibroblasts, Autosomal Recessive, Deficit, and fibroblasts
Peroxisomes perform a multitude of biosynthetic and catabolic functions, many of which are related to lipid metabolism. Peroxisomal disorders result either from deficiency of a single peroxisomal enzyme or protein, or from a defect in the... more
Peroxisomes perform a multitude of biosynthetic and catabolic functions, many of which are related to lipid metabolism. Peroxisomal disorders result either from deficiency of a single peroxisomal enzyme or protein, or from a defect in the complex mechanism of peroxisomal biogenesis, resulting in deficiency of several or multiple peroxisomal functions. These can be assessed by a battery of biochemical assays, enabling a biochemical phenotype to be defined that is specific and diagnostic for each of the peroxisomal disorders. Some peroxisomal disorders have unique and specific clinical phenotypes, which may be diagnostic. Others share patterns of clinical abnormalities (particularly neurological dysfunction, craniofacial dysmorphism, skeletal defects, sensory deafness, retinopathy) consistent with defined clinical phenotypes, but with considerable overlap and heterogeneity. To a certain extent, the clinical features of a particular disorder reflect the accumulation or deficiency of sp...
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Giardia lamblia infection was identified in 33 of 89 (37%) 3-month-old to 3-yr-old children who were followed with monthly stool examinations for up to 12 months in a day care center. The infection was mainly asymptomatic and usually... more
Giardia lamblia infection was identified in 33 of 89 (37%) 3-month-old to 3-yr-old children who were followed with monthly stool examinations for up to 12 months in a day care center. The infection was mainly asymptomatic and usually associated with prolonged carriage of the parasite. There were no significant differences for height and weight achievements and mean hemoglobin values between Giardia-positive and Giardia-negative children. However, Giardia-positive children tended to achieve higher weight and height for age than Giardia-negative children; weight for age was above the 50th percentile in 69% of Giardia-positive vs. 40% of Giardia-negative children (alpha = 0.01). Giardia-positive children tended to have fewer symptoms related to the gastrointestinal and respiratory tracts as recorded by a weekly questionnaire. Lactase deficiency was detected by breath hydrogen testing in 8 of 26 Giardia-positive vs. only 1 of 21 Giardia-negative children (P less than 0.02). Healthy day care children with asymptomatic Giardia infection show no disadvantage and perhaps even an advantage in nutritional status and freedom from other illnesses.
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Simultaneous occurrence of Henoch-Schönlein purpura (HSP) in family members is not well documented. We describe simultaneous onset of HSP in two sisters 1 day after the wearing of new synthetic slippers. Such an occurrence of the disease... more
Simultaneous occurrence of Henoch-Schönlein purpura (HSP) in family members is not well documented. We describe simultaneous onset of HSP in two sisters 1 day after the wearing of new synthetic slippers. Such an occurrence of the disease implies a common cause, however, in most patients the search for a causative agent is usually futile. There was no clear evidence of infection in our patients. The association of the appearance of the disease with the use of the slippers in our patients could indicate a possible, although unlikely, cause for their HSP.
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The ribosomal RNA (rRNA) genes in Giardia lamblia are present as short tandem arrays of a 5.6 Kb repeat unit on at least six telomeres. Four of these telomeres have the same overall organisation comprising a domain ranging in size from 25... more
The ribosomal RNA (rRNA) genes in Giardia lamblia are present as short tandem arrays of a 5.6 Kb repeat unit on at least six telomeres. Four of these telomeres have the same overall organisation comprising a domain ranging in size from 25 to 300 Kb, delineated chromosome internally by a conserved island of restriction enzyme sites. Cloned lines of G. lamblia derived from the WB strain contain polymorphic subsets of chromosomes encoding rRNA genes. However, changes in the size of the rRNA telomere domains of these polymorphic chromosomes alone cannot account for the total size changes in the chromosomes. The rearrangement events are very frequent: 60% of subcloned lines had discrete rearranged karyotypes that differed from each other, suggesting either an estimated rearrangement rate that may be as high as 3% per division or a cloning-induced rearrangement event. The extreme plasticity of the genome has obvious implications for the maintenance of a functional genome and the control of gene expression in Giardia.
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Glutaric aciduria type 1 (GA1) and D-2-hydroxyglutaric aciduria ( D-2-HGA) are cerebral organic acidurias characterized by the excretion of 3-hydroxyglutaric and D-2-hydroxyglutaric acids, respectively. GA1 is caused by a deficiency of... more
Glutaric aciduria type 1 (GA1) and D-2-hydroxyglutaric aciduria ( D-2-HGA) are cerebral organic acidurias characterized by the excretion of 3-hydroxyglutaric and D-2-hydroxyglutaric acids, respectively. GA1 is caused by a deficiency of glutaryl-CoA dehydrogenase encoded by the GCDH gene; the biochemical and genetic basis of D-2-HGA is unknown. We diagnosed GA1 in the son of consanguineous Palestinian parents, and D-2-HGA in his sister and brother. All three siblings were neurologically and developmentally normal. A small but abnormal increase in excretion of D-2-hydroxyglutaric acid was also found in the sibling with GA1. These observations suggested a possible pathophysiological link between these two disorders. The sibling with GA1 was homozygous whilst his siblings with D-2-HGA were heterozygous for a 1283 C>T missense mutation (T416I) in exon 11 of the GCDH gene. However, sequence analysis of the GCDH gene in 8 additional unrelated patients with D-2-HGA and 3 with combined D/ L-2-HGA did not reveal any pathogenic mutations. The biochemical and genetic basis of D-2-HGA remains to be determined.
Research Interests: Humans, Mutation, Female, Male, Siblings, and 4 moreNewborn Infant, Neuropediatrics, Neurosciences, and Child preschool
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Giardia lamblia infection was documented by jejunal biopsy in a previously healthy 2-year-old boy with acute onset of hypoproteinemia due to protein-losing enteropathy. All symptoms and abnormal laboratory findings resolved with... more
Giardia lamblia infection was documented by jejunal biopsy in a previously healthy 2-year-old boy with acute onset of hypoproteinemia due to protein-losing enteropathy. All symptoms and abnormal laboratory findings resolved with anti-Giardia therapy. This is only the second case report of giardiasis with documented protein-losing enteropathy. Further application of the fecal alpha 1-antitrypsin assay may help to clarify the relationship between Giardia infection and protein-losing enteropathy and its role in development of malnutrition.
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A child with chronic granulomatous disease developed an antral-pyloric obstruction, followed a month later by a postbulbar duodenal obstruction. At both areas, there was no evidence of an anatomical lesion, and some improvement in the... more
A child with chronic granulomatous disease developed an antral-pyloric obstruction, followed a month later by a postbulbar duodenal obstruction. At both areas, there was no evidence of an anatomical lesion, and some improvement in the passage of barium was observed following glucagon and metoclopramide administration. Presumably, symptoms have resulted from a functional disturbance of gastrointestinal motility.
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A 19-month-old girl with developmental delay was found to have moderately elevated plasma citrulline and mildly elevated plasma arginine concentrations. Dietary history revealed that she consumed large quantities of watermelon (Citrullus... more
A 19-month-old girl with developmental delay was found to have moderately elevated plasma citrulline and mildly elevated plasma arginine concentrations. Dietary history revealed that she consumed large quantities of watermelon (Citrullus vulgaris), a fruit containing high free citrulline and arginine concentrations. In order to determine whether the patient's high watermelon intake could account for her elevated plasma citrulline and arginine concentrations, we studied the response of plasma citrulline and arginine to ingestion of watermelon in six healthy adult volunteers. All developed markedly elevated plasma citrulline (mean maximum 593 micromol/L, range 386-1069) and moderately elevated plasma arginine (mean maximum 199 micromol/L, range 128-251). Physicians and laboratory personnel performing metabolic investigations should be aware of watermelon-induced citrullinaemia. Its hallmarks are elevated plasma citrulline, and to a lesser extent arginine, in the absence of orotic or arginosuccinic aciduria or hyperammonaemia. This phenomenon has implications for the management of patients with urea cycle and related disorders.
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L-2-hydroxyglutaric aciduria (L-2-HGA) is a rare inherited autosomal recessive neurometabolic disorder caused by mutations in the gene encoding L-2-hydroxyglutarate dehydrogenase. An assay to evaluate L-2-hydroxyglutarate dehydrogenase... more
L-2-hydroxyglutaric aciduria (L-2-HGA) is a rare inherited autosomal recessive neurometabolic disorder caused by mutations in the gene encoding L-2-hydroxyglutarate dehydrogenase. An assay to evaluate L-2-hydroxyglutarate dehydrogenase (L-2-HGDH) activity in fibroblast, lymphoblast and/or lymphocyte lysates has hitherto been unavailable. We developed an L-2-HGDH enzyme assay in cell lysates based on the conversion of stable-isotope-labelled L-2-hydroxyglutarate to 2-ketoglutarate, which is converted into L-glutamate in situ. The formation of stable isotope labelled L-glutamate is therefore a direct measure of L-2-HGDH activity, and this product is detected by liquid chromatography-tandem mass spectrometry. A deficiency of L-2-HGDH activity was detected in cell lysates from 15 out of 15 L-2-HGA patients. Therefore, this specific assay confirmed the diagnosis unambiguously affirming the relationship between molecular and biochemical observations. Residual activity was detected in cells derived from one L-2-HGA patient. The L-2-HGDH assay will be valuable for examining in vitro riboflavin/FAD therapy to rescue L-2-HGDH activity.
Research Interests: Genetics, Nutrition, Research Design, Glutamate, Humans, and 19 moreStable Isotope, Calibration, Animals, Cell, Tandem Mass Spectrometry, High Performance Liquid Chromatography, Enzyme, Implementation, Clinical Sciences, High Pressure Liquid Chromatography, Rats, Liquid Chromatography, Deficiency, Assay, Lymphocytes, Human Fibroblasts, Autosomal Recessive, Deficit, and fibroblasts
Research Interests: Vitamins, Islam, Humans, Child, Mutation, and 6 moreFemale, Male, Jews, Clinical Sciences, Coenzyme Q, and Child preschool
... Pedia-trics 9 : 748 9. Miler ME (1969) Phagocytosis in the new-born infant: humoral and cellular factors. ... 1 Department of Pediatrics, University of Milan z Fleming Laboratory 3 Department of Microbiology ICP Milan 4... more
... Pedia-trics 9 : 748 9. Miler ME (1969) Phagocytosis in the new-born infant: humoral and cellular factors. ... 1 Department of Pediatrics, University of Milan z Fleming Laboratory 3 Department of Microbiology ICP Milan 4 "Regina Elena" Hospital, Department of Neonatology, Milan ...
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Research Interests: Adolescent, Humans, Smooth muscle, Muscular Dystrophy, Female, and 12 moreMuscular Dystrophies, Male, Duchenne Muscular Dystrophy, Clinical Sciences, Adult, Public health systems and services research, Degeneration, Neuromuscular diseases, Gastrointestinal motility, Gastrointestinal Transit Time, Transit Time, and Small Intestine
A 6-year-old girl presented with acute thrombocytopenic purpura. Hepatitis B surface antigenaemia was present at the time of this illness, and 8 weeks later she developed acute icteric hepatitis B. Screening for hepatitis B virus should... more
A 6-year-old girl presented with acute thrombocytopenic purpura. Hepatitis B surface antigenaemia was present at the time of this illness, and 8 weeks later she developed acute icteric hepatitis B. Screening for hepatitis B virus should be considered in children with apparently idiopathic thrombocytopenic purpura.
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Non-ketotic hyperglycinaemia (NKH) is a devastating neurometabolic disorder leading, in its classical form, to early death or severe disability and poor quality of life in survivors. Affected neonates may need ventilatory support during a... more
Non-ketotic hyperglycinaemia (NKH) is a devastating neurometabolic disorder leading, in its classical form, to early death or severe disability and poor quality of life in survivors. Affected neonates may need ventilatory support during a short period of respiratory depression. The transient dependence on ventilation dictates urgency in decision-making regarding withdrawal of therapy. The occurrence of patients with apparent transient forms of the disease, albeit rare, adds uncertainty to the prediction of clinical outcome and dictates that the current practice of withholding or withdrawing therapy in these neonates be reviewed. Both bioethics and law take the view that treatment decisions should be based on the best interests of the patient. The medical-ethics approach is based on the principles of non-maleficence, beneficence, autonomy and justice. The law relating to withholding or withdrawing life-sustaining treatment is complex and varies between jurisdictions. Physicians treating newborns with NKH need to provide families with accurate and complete information regarding the disease and the relative probability of possible outcomes of the neonatal presentation and to explore the extent to which family members are willing to take part in the decision making process. Cultural and religious attitudes, which may potentially clash with bioethical and juridical principles, need to be considered.
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In an attempt to study the variation of associations between HLA and rheumatoid disease a population of 44 Ashkenazi and 29 non-Ashkenazi patients with Rheumatoid Arthritis were tested for HLA-A, B, C and DR antigens and compared with the... more
In an attempt to study the variation of associations between HLA and rheumatoid disease a population of 44 Ashkenazi and 29 non-Ashkenazi patients with Rheumatoid Arthritis were tested for HLA-A, B, C and DR antigens and compared with the relevant control groups. In contrast to the results obtained in Middle European or North American Caucasians, Rheumatoid Arthritis in Israel is not associated with B15 and Cw3, indicating that it is very unlikely that B- and C-locus antigens are involved in coding for disease susceptibility for RA. The allele DR4 which is found associated with RA in almost all populations tested so far was in the total patient group (47.9%) slightly but not significantly more frequent than in the control group (38.3%). This difference was entirely due to a nonsignificant increase in the frequency of DR4 in the Ashkenazi patients (54.5%) compared to controls (40%), while the frequency of DR4 in non-Ashkenazi patients and controls was virtually identical (38.0% vs 36.7%). Another surprising finding was that the frequency of HLA-DR1, which has been reported to be increased in different populations of patients with RA was found to be completely normal in the present study on Israeli patients. The alleles of the Bf and the GLO system did not show any significant difference between patients and controls.(ABSTRACT TRUNCATED AT 250 WORDS)
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Hyperargininemia is a progressive neurometabolic disorder caused by deficiency of hepatic cytosolic arginase I, resulting from mutations in the ARG1 gene. We diagnosed arginase deficiency in a three-year-old male child of first-cousin... more
Hyperargininemia is a progressive neurometabolic disorder caused by deficiency of hepatic cytosolic arginase I, resulting from mutations in the ARG1 gene. We diagnosed arginase deficiency in a three-year-old male child of first-cousin Palestinian Arab parents. Prenatal diagnosis of an unaffected fetus was achieved in the second trimester of a subsequent pregnancy by cordocentesis and analysis of arginase activity in fetal erythrocytes. ARG1 mutation analysis in the proband revealed homozygosity for a deletion of 10,753 bp extending from the first intron to beyond the poly (A) site of the gene. This is the first gross deletion in the ARG1 gene to be identified and the first mutation to be described in an arginase-deficient patient of this ethnic origin. The identification of the ARG1 deletion in this family enabled first-trimester prenatal diagnosis in a subsequent pregnancy by multiplex PCR analysis performed on chorionic villous DNA.
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Research Interests: Genetics, Humans, Mutation, Female, Male, and 6 moreFatty Acid Oxidation, Infant, Clinical Sciences, L-carnitine, Adult, and Organic Acid
Research Interests: Molecular Genetics, Adolescent, Disease susceptibility, Early Childhood, Humans, and 21 moreChild, Mice, Female, Animals, Inborn errors of metabolism, Male, Jews, Fatty Acid Oxidation, Infant, Phenotype, Respiratory Failure, Clinical Sciences, Newborn Infant, Spectrum, White matter, Adult, Base Sequence, Developmental delay, Recombinant Proteins, Congenital abnormalities, and Founder Effect
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Research Interests: Electron Microscopy, Cognition, Spectroscopy, Treatment Outcome, Creatine, and 20 moreMolecular Genetics, Magnetic Resonance Spectroscopy, Adolescent, Mental Retardation, Humans, Child, Adaptive behavior, Female, Male, Mitochondrial Respiratory Chain, Tandem Mass Spectrometry, Clinical Sciences, Cognitive Function, Mitochondrial, Metabolic Disorder, Clinical Presentation, L, Nucleotides, Organic Acid, and Creatine Phosphate
The rare autosomal recessive disorder pyridoxine 5'-phosphate oxidase (PNPO) deficiency is a recently described cause of neonatal and infantile seizures. Clinical evaluation, and biochemical and genetic... more
The rare autosomal recessive disorder pyridoxine 5'-phosphate oxidase (PNPO) deficiency is a recently described cause of neonatal and infantile seizures. Clinical evaluation, and biochemical and genetic testing, were performed on a neonate with intractable seizures who did not respond to anticonvulsant drugs and pyridoxine. Sequencing of the PNPO gene revealed a novel homozygous c.284G>A transition in exon 3, resulting in arginine to histidine substitution and reduced activity of the PNPO mutant to 18% relative to the wild type. This finding enabled molecular prenatal diagnosis in a subsequent pregnancy, accurate genetic counseling in the large inbred family, and population screening.