Richard W. Erbe

Food reinforcement, the dopamine D2 receptor genotype, and energy intake in obese and nonobese humans.

The authors measured food reinforcement, polymorphisms of the dopamine D2 receptor (DRD2) and dopamine transporter (DAT1) genes, and laboratory energy intake in 29 obese and 45 nonobese humans 18-40 years old. Food reinforcement was greater in obese than in nonobese individuals, especially in obese individuals with the TaqI A1 allele. Energy intake was greater for individuals high in food reinforcement and greatest in those high in food reinforcement with the TaqI A1 allele. No effect of the DAT1 genotype was observed. These data show that individual differences in food reinforcement may be important for obesity and that the DRD2 genotype may interact with food reinforcement to influence energy intake.

Newborn screening for Krabbe disease: the New York State model.

Krabbe disease is a rare inherited neurologic disorder affecting the central and peripheral nervous systems. The disease has four phenotypes: early infantile, later onset, adolescent, and adult. The only known treatment is hematopoietic stem cell transplantation, which is, in the early infantile form of the disease, most beneficial if performed before onset of clinical symptoms. In August 2006, New York State began screening all newborns for Krabbe disease. A rapid and accurate technique for assessing galactocerebrosidase activity and performing DNA mutation analysis had been developed. Interpreting these results was limited, however, because neither enzyme activity nor genetic mutation reliably predicts phenotype. A series of initiatives were therefore developed by a multidisciplinary group of neurologists, geneticists, metabolic pediatricians, neurodevelopmental pediatricians, and transplant physicians (the Krabbe Consortium of New York State) to enhance the effectiveness of the newborn screening program. A standardized clinical evaluation protocol was designed based on the available literature, criteria for transplantation for the early infantile phenotype were formulated, a clinical database and registry was developed, and a study of developmental and functional outcomes was instituted. This multidisciplinary standardized approach to evaluating infants who have positive results on newborn screening may serve as a model for other states as they begin the process of screening for Krabbe disease and other lysosomal storage disorders.

Phenylketonuria in adulthood: a collaborative study.

During 1967–1983, the Maternal and Child Health Division of the Public Health Services funded a collaborative study of 211 newborn infants identified on newborn screening as having phenylketonuria (PKU). Subsequently, financial support was provided by the National Institute of Child Health and Human Development (NICHD). The infants were treated with a phenylalanine (Phe)-restricted diet to age 6 years and then randomized either to continue the diet or to discontinue dietary treatment altogether. One hundred and twenty-five of the 211 children were then followed until 10 years of age. In 1998, NICHD scheduled a Consensus Development Conference on Phenylketonuria and initiated a study to follow up the participants from the original Collaborative Study to evaluate their present medical, nutritional, psychological, and socioeconomic status.Fourteen of the original clinics (1967–1983) participated in the Follow-up Study effort. Each clinic director was provided with a list of PKU subjects who had completed the original study (1967–1983), and was asked to evaluate as many as possible using a uniform protocol and data collection forms. In a subset of cases, magnetic resonance imaging and spectroscopy (MRI/MRS) were performed to study brain Phe concentrations.The medical evaluations revealed that the subjects who maintained a phenylalanine-restricted diet reported fewer problems than the diet discontinuers, who had an increased rate of eczema, asthma, mental disorders, headache, hyperactivity and hypoactivity. Psychological data showed that lower intellectual and achievement test scores were associated with dietary discontinuation and with higher childhood and adult blood Phe concentrations. Abnormal MRI results were associated with higher brain Phe concentrations. Early dietary discontinuation for subjects with PKU is associated with poorer outcomes not only in intellectual ability, but also in achievement test scores and increased rates of medical and behavioural problems.

Translation and translocation of defined RNA messengers

Abstract A purified system for protein synthesis, derived from Esherichia coli , makes use of small, synthetic mRNAs initiated by the fMet ‡ codon, AUG, followed by a sequence of 3, 6 or 9 uridylic acid residues. These di-, tri- and tetra-codons direct the binding of fMet- and Phe-tRNA to ribosomes and the synthesis of the corresponding fMet-initiated di-, tri- and tetrapeptides. This system, directing the synthesis of unique and conveniently detected oligopeptide products, has permitted us to correlate the soluble elements required for protein synthesis with specific steps in the translation of initial and succeeding codons. Complete translation of these small mRNAs has certain of the stringent requirements necessary for the accurate cell-free translation of naturally occurring RNA messengers. Thus, initiation factors, fMet-tRNA and GTP must be provided. After recognition of the first codon and formation of the initial complex, one of two transfer factors, in the presence of GTP, catalyzes a binding reaction in which the second (first internal) codon is recognized. This permits formation of the dipeptide, fMet-Phe, but does not permit translation of succeeding codons. A second transfer factor, probably an enzyme, participates in a translocation reaction in which the third codon is made available for translation, apparently displacing the second codon at the recognition site on the ribosome. In addition, the complex formed between peptidyl-tRNA, mRNA and ribosome is stabilized, possibly by translocation of the peptidyl-tRNA from a site of lesser affinity to one of greater affinity on the ribosome. The role of GTP in the translocation reaction will be certain only when it has been uncoupled from its participation in the binding reaction. Once requirements for translation of the third codon have been met no further additions are necessary for elongation of the peptide chain.

Inherited Gastrointestinal-Polyposis Syndromes

Isolated polyps in the gastrointestinal tract, particularly in the colon, are relatively common, whereas only occasionally do patients have large numbers of polyps. Many of these patients have one ...

A Phase 3 Trial of Sebelipase Alfa in Lysosomal Acid Lipase Deficiency

BACKGROUND Lysosomal acid lipase is an essential lipid-metabolizing enzyme that breaks down endocytosed lipid particles and regulates lipid metabolism. We conducted a phase 3 trial of enzyme-replacement therapy in children and adults with lysosomal acid lipase deficiency, an underappreciated cause of cirrhosis and severe dyslipidemia. METHODS In this multicenter, randomized, double-blind, placebo-controlled study involving 66 patients, we evaluated the safety and effectiveness of enzyme-replacement therapy with sebelipase alfa (administered intravenously at a dose of 1 mg per kilogram of body weight every other week); the placebo-controlled phase of the study was 20 weeks long and was followed by open-label treatment for all patients. The primary end point was normalization of the alanine aminotransferase level. Secondary end points included additional disease-related efficacy assessments, safety, and side-effect profile. RESULTS Substantial disease burden at baseline included a very high level of low-density lipoprotein cholesterol (≥190 mg per deciliter) in 38 of 66 patients (58%) and cirrhosis in 10 of 32 patients (31%) who underwent biopsy. A total of 65 of the 66 patients who underwent randomization completed the double-blind portion of the trial and continued with open-label treatment. At 20 weeks, the alanine aminotransferase level was normal in 11 of 36 patients (31%) in the sebelipase alfa group and in 2 of 30 (7%) in the placebo group (P=0.03), with mean changes from baseline of -58 U per liter versus -7 U per liter (P<0.001). With respect to prespecified key secondary efficacy end points, we observed improvements in lipid levels and reduction in hepatic fat content (P<0.001 for all comparisons, except P=0.04 for triglycerides). The number of patients with adverse events was similar in the two groups; most events were mild and were considered by the investigator to be unrelated to treatment. CONCLUSIONS Sebelipase alfa therapy resulted in a reduction in multiple disease-related hepatic and lipid abnormalities in children and adults with lysosomal acid lipase deficiency. (Funded by Synageva BioPharma and others; ARISE ClinicalTrials.gov number, NCT01757184.).

The long-term outcomes of presymptomatic infants transplanted for Krabbe disease: Report of the workshop held on July 11 and 12, 2008, Holiday Valley, New York

Krabbe disease (globoid cell leukodystrophy) is an autosomal recessive disorder of white matter resulting from deficiency of galactosylceramide beta-galactosidase (GALC) and the consequent accumulation of galactosylceramide and psychosine. Although most patients present within the first 6 months of life, i.e., the early infantile or “classic” phenotype, others present later in life including in adolescence and adulthood. The only available treatment for infants with early infantile Krabbe disease is hematopoietic cell transplantation (HCT), typically using umbilical cord blood. Although transplanted children are far better neurologically than they would have been had they followed the typical fulminant course of early infantile Krabbe disease, anecdotal reports have surfaced suggesting that the majority of presymptomatic children transplanted for Krabbe disease have developed motor and language deterioration. The cause and extent of the deterioration is unknown at this time. With the advent of universal newborn screening for Krabbe disease in New York State and the projected start of screening in Illinois in 2010, understanding the outcome of treatment becomes of paramount importance. Thus, the purpose of this workshop was to bring together child neurologists, geneticists, neurodevelopmental pediatricians, transplanters, neuroradiologists, neurophysiologists, developmental neurobiologists, neuroscientists, and newborn screeners to review the results of the transplantation experience in humans and animals and, if neurologic deterioration was confirmed, develop possible explanations as to causation. This workshop was the first attempt at a multicenter crossdiscipline evaluation of the results of HCT for Krabbe disease. A broad range of individuals participated, including clinicians, academicians, and authorities from the National Institutes of Health, American College of Medical Genetics, and Department of Health and Human Services.

Inborn Errors of Folate Metabolism

(First of Two Parts) SINCE 1961, five and possibly six new disorders have been attributed to congenital defects in the uptake or utilization of folic acid, an essential vitamin in man. Although the...

Attitudes toward abortion among parents of children with cystic fibrosis.

BACKGROUND DNA prenatal diagnosis for cystic fibrosis (CF) has been available for parents of affected children since late 1985. METHODS Using anonymous questionnaires, we surveyed 395 parents of children with CF at 12 New England CF centers with regard to 12 maternal or family situations and 11 fetal characteristics; 271 (68%) responded. RESULTS The majority supported legal abortion in the first trimester for all 23 situations; 58% would abort for severe mental retardation (MR), 40% would abort for a genetic disorder leading to death before age five years, 41% for a child bedridden for life, 35% for moderate MR, 20% for CF and 17% for a severe incurable disorder starting at age 40 years. Few would abort for a disorder starting at age 60 years, for genetic susceptibility to alcoholism or for sex selection. Variables most strongly related to abortion for CF were attitudes of spouse, respondents siblings, and CF doctor toward abortion for CF as well as infrequent attendance at religious services. CONCLUSIONS Prenatal diagnosis may not reduce substantially the number of CF births to parents of CF children because most do not accept abortion for CF.

Reversion to methionine independence by malignant rat and SV40-transformed human fibroblasts.

Abstract Although many lines of malignant and transformed cells are unable to grow in folate- and cobalamin-supplemented medium in which methionine is replaced by homocysteine its immediate metabolic precursor, rare cells from these lines regained the normal ability to grow under these conditions. Six revertant lines, one from Walker-256 rat breast carcinoma cells and five from SV40-transformed human fibroblasts, have been characterized with regard to growth and three measures of methionine biosynthetic capacity: methionine synthetase and methylenetetrahydrofolate reductase activities in cell extracts, and uptake of label from [5- 14 C]methyltetrahydrofolate by intact cells. When all three measures of methionine biosynthetic capacity were considered, two revertants isolated from SV40-transformed cells had regained the ability to grow like normal cells in homocysteine medium without substantial changes in these measures. Increased methionine biosynthesis thus is not a prerequisite to reversion of the methionine auxotrophy present in the transformed parental lines.