The asymmetry of antimatter in the proton.

The fundamental building blocks of the proton-quarks and gluons-have been known for decades. However, we still have an incomplete theoretical and experimental understanding of how these particles and their dynamics give rise to the quantum bound state of the proton and its physical properties, such as its spin1. The two up quarks and the single down quark that comprise the proton in the simplest picture account only for a few per cent of the proton mass, the bulk of which is in the form of quark kinetic and potential energy and gluon energy from the strong force2. An essential feature of this force, as described by quantum chromodynamics, is its ability to create matter-antimatter quark pairs inside the proton that exist only for a very short time. Their fleeting existence makes the antimatter quarks within protons difficult to study, but their existence is discernible in reactions in which a matter-antimatter quark pair annihilates. In this picture of quark-antiquark creation by the strong force, the probability distributions as a function of momentum for the presence of up and down antimatter quarks should be nearly identical, given that their masses are very similar and small compared to the mass of the proton3. Here we provide evidence from muon pair production measurements that these distributions are considerably different, with more abundant down antimatter quarks than up antimatter quarks over a wide range of momenta. These results are expected to revive interest in several proposed mechanisms for the origin of this antimatter asymmetry in the proton that had been disfavoured by previous results4, and point to future measurements that can distinguish between these mechanisms.

Cognitive and adaptive functioning after liver transplantation for maple syrup urine disease: a case series.

MSUD is a complex metabolic disorder that has been associated with central nervous system damage, developmental delays, and neurocognitive deficits. Although liver transplantation provides a metabolic cure for MSUD, changes in cognitive and adaptive functioning following transplantation have not been investigated. In this report, we present data from 14 patients who completed cognitive and adaptive functioning testing pre- and one yr and/or three yr post-liver transplantation. Findings show either no significant change (n=8) or improvement (n=5) in IQ scores pre- to post-liver transplantation. Greater variability was observed in adaptive functioning scores, but the majority of patients evidenced no significant change (n=8) in adaptive scores. In general, findings indicate that liver transplantation minimizes the likelihood of additional central nervous system damage, providing an opportunity for possible stabilization or improvement in neurocognitive functioning.

The biochemical phenotypes of two inborn errors in the biosynthesis of aldosterone.

Two inborn errors in the methyl oxidation of corticosterone to form aldosterone correspond to the two oxygenation-hydroxylation reactions required for this transformation. Both defects are characterized by overproduction of corticosterone of glomerulosa zone origin and deficient synthesis of aldosterone. In the type 1 corticosterone methyl oxidase defect (CMO I) impairment in the first step is reflected in decreased production of 18-hydroxycorticosterone while in CMO II an impaired second step is characterized by overproduction of 18-hydroxycorticosterone leading to an increased 18-hydroxycorticosterone:aldosterone metabolite ratio as a diagnostic index. This metabolite ratio may be increased somewhat in CMO I but not as much as in CMO II. The absolute value of 18-hydroxycorticosterone is a more reliable discriminator as is the corticosterone:18-hydroxycorticosterone metabolite ratio which is increased in CMO I and decreased in CMO II. On the basis of these findings, a North American kindred is reclassified as CMO I making this defect the more prevalent form in the Western Hemisphere. The two biochemical phenotypes will very likely describe different mutations in the gene encoding cytochrome P-450 CMO.

An autosomal recessive disorder with posterior column ataxia and retinitis pigmentosa.

We report an autosomal recessive form of ataxia that is not allelic to Friedreich's disease in six individuals from a large kindred with family origins traced to a common founder of German-Swiss descent. The disorder begins during early childhood with a concentric contraction of the visual fields and proprioceptive loss. Eventually blindness, a severe sensory ataxia, achalasia, scoliosis, and inanition develop by third decade. Inversion recovery MRIs of the spinal cord in affected individuals demonstrate a hyperintense signal in the posterior columns. Finding the gene responsible for this disorder may aid in our understanding of the mechanisms that cause sensory neuronal degeneration.

Posterior column ataxia with retinitis pigmentosa (AXPC1) maps to chromosome 1q31-q32.

OBJECTIVE: To establish a genetic linkage between highly polymorphic microsatellite loci and the disease locus responsible for an autosomal recessive neurodegenerative syndrome that causes posterior column ataxia and retinitis pigmentosa. BACKGROUND: The authors reported previously a genetic syndrome that causes visual impairment, proprioceptive loss, sensory ataxia, and areflexia in affected individuals from a large, inbred family belonging to a sectarian population that has been genetically semi-isolated from mainstream society for several centuries. METHODS: To find the disease locus responsible for this condition, the authors performed a genome-wide search using genetic loci spaced at 10 to 20-cM intervals spanning human chromosomes (chr) 1-22. Pairwise linkage analysis, multipoint linkage analysis, and haplotype reconstruction were used to delineate the candidate region containing the disease gene. RESULTS: After testing 226 loci that covered the entire genome, the authors identified a maximum lod score of 8.94 at a recombination fraction of 0.00 for locus D1S2692. Additional analyses placed the disease gene, AXPC1, in an 8.3-cM interval flanked by markers D1S2692 and D1S414 on chr 1q31-q32. CONCLUSIONS: This study suggests that a single genetic mutation can cause selective degeneration of the posterior columns of the spinal cord and retina. Finding the gene responsible for this syndrome may increase our understanding of the molecular basis of diseases that affect sensory neurons.

Glutaric aciduria type I: a common cause of episodic encephalopathy and spastic paralysis in the Amish of Lancaster County, Pennsylvania.

We have diagnosed type I glutaric aciduria (GA-I) in 14 children from 7 Old Order Amish families in Lancaster County, Pennsylvania. An otherwise rare disorder, GA-I appears to be a common cause of acute encephalopathy and cerebral palsy among the Amish. The natural history of the disease, which was previously unrecognized in this population, is remarkably variable and ranges from acute infantile encephalopathy and sudden death to static extrapyramidal cerebral palsy to normal adult. Ten patients first manifested the disease between 3 and 18 months at the time of an acute infectious illness. Four of these children died in early childhood, also during acute illnesses. However, there has been little progression of the neurological disease after age 5 years in the surviving children and intellect usually has been preserved, even in children with severe spastic paralysis. When well, patients have plasma glutaric acid concentrations ranging from 4.8 to 14.2 mumol/liter (nl 0-5.6 mumol/liter) and urinary glutaric acid concentrations from 12.5 to 196 mg/g creatinine (nl 0.5-8.4 mg/g creatinine). We have found that GA-I can be diagnosed in the Amish by measurement of urinary glutaric acid concentrations using isotope-dilution gas chromatography/mass spectrometry, whereas the diagnosis can easily be missed by routine urine organic acid gas chromatography.(ABSTRACT TRUNCATED AT 250 WORDS)

3-Hydroxyoctanoic aciduria: identification of a new organic acid in the urine of a patient with non-ketotic hypoglycemia.

A four-month-old child with non-ketotic hypoglycemia and rapidly progressive cirrhosis excreted in her urine large amounts of two unidentified organic acids in addition to a spectrum of saturated, unsaturated, and 3-hydroxy dicarboxylic acids in her urine. Gas chromatography/mass spectrometry of the trimethylsilyl derivative of one of the unknown compounds suggested the structure of 3-hydroxyoctanoic acid, which was confirmed by similar analysis of the authentic compound. The same organic acid was found in the child's plasma. The significance of 3-hydroxyoctanoic aciduria as a possible marker for a primary defect of 3-hydroxy fatty acid metabolism is discussed.

Elective liver transplantation for the treatment of classical maple syrup urine disease.

An 8.5-year-old girl with classical maple syrup urine disease (MSUD) required liver transplantation for hypervitaminosis A and was effectively cured of MSUD over an 8-year clinical follow-up period. We developed a collaborative multidisciplinary effort to evaluate the effects of elective liver transplantation in 10 additional children (age range 1.9-20.5 years) with classical MSUD. Patients were transplanted with whole cadaveric livers under a protocol designed to optimize safe pre- and post-transplant management of MSUD. All patients are alive and well with normal allograft function after 106 months of follow-up in the index patient and a median follow-up period of 14 months (range 4-18 months) in the 10 remaining patients. Leucine, isoleucine and valine levels stabilized within 6 hours post-transplant and remained so on an unrestricted protein intake in all patients. Metabolic cure was documented as a sustained increase in weight-adjusted leucine tolerance, normalization of plasma concentration relationships among branched-chain and other essential and nonessential amino acids, and metabolic and clinical stability during protein loading and intercurrent illnesses. Costs and risks associated with surgery and immune suppression were similar to other pediatric liver transplant populations.

Restriction endonuclease analysis of the DNA from varicella-zoster virus: stability of the DNA after passage in vitro.

DNA was extracted from nucleocapsids isolated from WI-38 cells infected with two different strains of varicella-zoster virus (VZV). The DNAs were treated with each of six restriction endonucleases (EcoRI, HindIII, Bg/I, Bg/II, Sal I and Bam-HI) and small, but reproducible differences in restriction endonuclease patterns were observed. These strains were passaged in WI-38 cells and in primary guinea-pig embryo (GPE) cells, followed by restriction endonuclease analysis of the DNAs. No changes were observed in the restriction prpofile of the DNA of one of the strains (VZV-KMcC) after 46 passages in WI-38 cells but small differences were observed after 72 passages. No changes were observed after 30 passages of another strain (VZV-AW) in WI-38 cells. Twenty passages of VZB-KMcC in GPE cells did result in minor alterations of its DNA. It was concluded that VZV DNA was sufficiently stable after multiple passages in WI-38 cells to make restriction endonuclease analysis a valuable epidemiological tool for strain differentiation.

3-Methylcrotonyl-coenzyme A carboxylase deficiency in Amish/Mennonite adults identified by detection of increased acylcarnitines in blood spots of their children.

Isolated 3-methylcrotonyl coenzyme A carboxylase (MCC) deficiency was documented in four adult women from the Amish/Mennonite population of Lancaster County, Pennsylvania. Metabolic and enzymatic investigations in these individuals were instituted after the detection of abnormal acylcarnitine profiles in blood spots obtained from their newborn children, in whom MCC activity was normal.

Gene structure and mutations of glutaryl-coenzyme A dehydrogenase: impaired association of enzyme subunits that is due to an A421V substitution causes glutaric acidemia type I in the Amish.

The structure of the human glutaryl coenzyme A dehydrogenase (GCD) gene was determined to contain 11 exons and to span approximately 7 kb. Fibroblast DNA from 64 unrelated glutaric acidemia type I (GA1) patients was screened for mutations by PCR amplification and analysis of SSCP. Fragments with altered electrophoretic mobility were subcloned and sequenced to detect mutations that caused GA1. This report describes the structure of the GCD gene, as well as point mutations and polymorphisms found in 7 of its 11 exons. Several mutations were found in more than one patient, but no one prevalent mutation was detected in the general population. As expected from pedigree analysis, a single mutant allele causes GA1 in the Old Order Amish of Lancaster County, Pennsylvania. Several mutations have been expressed in Escherichia coli, and all produce diminished enzyme activity. Reduced activity in GCD encoded by the A421V mutation in the Amish may be due to impaired association of enzyme subunits.

Abnormal hepatic sinusoidal bile acid transport in an Amish kindred is not linked to FIC1 and is improved by ursodiol.

BACKGROUND & AIMS: The mechanism for abnormal hepatic bile acid transport was investigated in an 18-month-old Amish boy who presented with pruritus, poor growth, and severe bleeding episodes. Serum bilirubin, gamma-glutamyltranspeptidase, and cholesterol levels were normal, but prothrombin time and partial thromboplastin time were prolonged and bone alkaline phosphatase level was elevated. METHODS AND RESULTS: Cholic acid plus chenodeoxycholic acid levels measured by capillary gas-chromatography were 32 times higher than control in serum (34.7 vs. 1.1+/-0.4 microg/dL) but were not detected in liver and were reduced in gallbladder bile. Treatment with ursodiol, a more hydrophilic bile acid, improved pruritus, produced 37% weight gain, and after 2 years reduced serum primary bile acid concentrations about 85%, while accounting for 71% of serum and 24% of biliary bile acid conjugates. On ursodiol therapy, hepatic bile acid synthesis was enhanced 2-fold compared with controls, and microscopy revealed chronic hepatitis without cholestasis. Three younger sisters with elevated serum bile acids responded positively to ursodiol. Microsatellite markers for the FIC1 (gene for Byler's disease) region in these 4 children were inconsistent with linkage to FIC1. CONCLUSIONS: Conjugated cholic acid and chenodeoxycholic acid were synthesized in the liver and secreted into bile but could not reenter the liver from portal blood and accumulated in serum. In contrast, unconjugated ursodiol entered the liver and was conjugated and secreted into bile. Thus, the enterohepatic circulation of all conjugated bile acids was interrupted at the hepatic sinusoidal basolateral membrane. Unconjugated ursodiol bypassed the hepatic uptake block to enlarge the biliary and intestinal bile acid pools. A mutation in FIC1 recognized among the Amish and linkage of the disorder to FIC1 were excluded.

A novel nemaline myopathy in the Amish caused by a mutation in troponin T1.

The nemaline myopathies are characterized by weakness and eosinophilic, rodlike (nemaline) inclusions in muscle fibers. Amish nemaline myopathy is a form of nemaline myopathy common among the Old Order Amish. In the first months of life, affected infants have tremors with hypotonia and mild contractures of the shoulders and hips. Progressive worsening of the proximal contractures, weakness, and a pectus carinatum deformity develop before the children die of respiratory insufficiency, usually in the second year. The disorder has an incidence of approximately 1 in 500 among the Amish, and it is inherited in an autosomal recessive pattern. Using a genealogy database, automated pedigree software, and linkage analysis of DNA samples from four sibships, we identified an approximately 2-cM interval on chromosome 19q13.4 that was homozygous in all affected individuals. The gene for the sarcomeric thin-filament protein, slow skeletal muscle troponin T (TNNT1), maps to this interval and was sequenced. We identified a stop codon in exon 11, predicted to truncate the protein at amino acid 179, which segregates with the disease. We conclude that Amish nemaline myopathy is a distinct, heritable, myopathic disorder caused by a mutation in TNNT1.

Diagnosis and management of glutaric aciduria type I.

Glutaric aciduria type I (GA1) is a preventable cause of acute brain damage in early childhood, leading to a severe dystonic-dyskinetic disorder that is similar to cerebral palsy and ranges from extreme hypotonia to choreoathetosis to rigidity with spasticity. Degeneration of the putamen and caudate typically occurs between 6 and 18 months of age and is probably linked to changes in metabolic demand caused by normal maturational changes and superimposed catabolic stress. Recognition of this biochemical disorder before the brain has been injured is essential to outcome. Diagnosis depends upon the recognition of relatively non-specific physical findings such as hypotonia, irritability and macrocephaly, and on performance of urine organic acid quantification by gas chromatography--mass spectrometry or selective searches of urine or blood specimens by tandem mass spectrometry for glutarylcarnitine. The diagnosis may also be suggested by characteristic findings on neuroimaging. In selected patients diagnosis can only be reached by enzyme assay. Specific current management by the authors of this paper includes pharmacological doses of L-carnitine, as well as dietary protein restriction. Metabolic decompensation must be treated aggressively to avoid permanent brain damage. Multicentre studies are needed to establish best methods of diagnosis and optimal therapy of this disorder.

Congenitally defective aldosterone biosynthesis in humans: inactivation of the P-450C18 gene (CYP11B2) due to nucleotide deletion in CMO I deficient patients.

CYP11B2, the gene coding for steroid 18-hydroxylase (P-450C18), has been recently shown to be the same gene as that for corticosterone methyl oxidase type I and type II (CMO I & II) which were previously postulated to catalyze the final two steps in the biosynthesis of aldosterone in humans. Molecular genetic analysis of CYP11B2 of three patients affected with CMO I deficiency has revealed that deletion of 5 nucleotides occurs exclusively in exon 1, resulting in a frameshift to form a stop codon in the same exon. Thus, P-450C18 is not produced at all due to the mutation, causing a complete lack of aldosterone biosynthesis in the patients. Restriction fragment length polymorphism analysis has demonstrated that the patients are homozygous and the unaffected parent is heterozygous as for the mutation, indicating that CMO I deficiency is inherited in an autosomal recessive manner. These results provide the molecular genetic basis for the characteristic biochemical phenotype of CMO I deficient patients.

Brain magnetic resonance imaging in suspected extrapyramidal cerebral palsy: observations in distinguishing genetic-metabolic from acquired causes.

Experienced clinicians recognize that some children who appear to have static cerebral palsy (CP) actually have underlying genetic-metabolic disorders. We report a series of patients with motor disorders seen in children with extrapyramidal CP in whom brain magnetic resonance imaging abnormalities provided important diagnostic clues in distinguishing genetic-metabolic disorders from other causes. One cause of static extrapyramidal CP, hypoxic-ischemic encephalopathy at the end of a term gestation, produces a characteristic pattern of hyperintense signal and atrophy in the putamen and thalamus. Other signal abnormalities and atrophy in the putamen, globus pallidus, or caudate can point to genetic-metabolic diseases, including disorders of mitochondrial and organic acid metabolism. Progress in understanding and treating genetic diseases of the developing brain makes it essential to diagnose disorders that masquerade as static CP. Brain magnetic resonance imaging is a useful diagnostic tool in the initial evaluation of children who appear to have CP.

Successful infection of the common marmoset (Callithrix jacchus) with human varicella-zoster virus.

The common marmoset, Callithrix jacchus, can be infected with human varicella-zoster virus (VZV), both wild-type strain KMcC and attenuated vaccine strain Oka/Merck. Infection was accomplished with either whole-cell-associated or cell extract VZV by combined oral-nasal-conjunctival application and was characterized by substantial and persistent anti-VZV antibody responses. The infectivity of VZV for marmosets was destroyed by treatment of inocula with heat or UV light. Diluted inocula with as few as 40 PFU/ml were infectious for marmosets. The lungs were demonstrated to be a major site of viral replication; both the presence of viral antigens and signs of pneumonia were demonstrated in lung tissues. Four serial passages of VZV KMcC were carried out in C. jacchus by a process of in vitro isolation and culturing of VZV from infected lung tissue and reapplication of the cultured isolates to fresh animals. The isolated viruses were identified as VZV both serologically and by restriction endonuclease analyses. The C. jacchus infectivity model should prove useful for determining the efficacy of subunit and live recombinant VZV vaccines as well as for the study of zoster.

Antibody assays suitable for assessing immune responses to live varicella vaccine.

An enzyme-linked immunosorbent assay for antibodies to varicella-zoster virus (VZV), using purified viral glycoproteins as antigen (gpELISA), was compared with other assays for measuring vaccine-induced antibody responses. The gpELISA was more sensitive than conventional assays, proved highly specific for VZV and agreed well with an assay for neutralizing antibody activity. It was successfully applied to large-scale testing of live varicella vaccine in humans.