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Biomedical subjects

H L Levy

Publications and source records attributed to H L Levy.

At least 91 records · Page 5Linked to original sources
PubMed1993

The use of gelatin capsules for ingestion of formula in dietary treatment of maternal phenylketonuria.

Maternal phenylketonuria (PKU) represents a high risk for birth defects, including mental retardation, in offspring. Thus, it could cancel gains represented by the prevention of PKU-induced mental retardation in the current generation. Effective dietary treatment of maternal PKU pregnancies could avoid this potentially tragic occurrence. However, dietary compliance is often difficult because a necessary component of the diet, medical nutritional formulas, often have an unpleasant taste and odour. We treated the second pregnancy of a phenylketonuric women who had required extended hospitalization during her first pregnancy because of poor formula tolerance, and who had similar difficulty in the second pregnancy. To alleviate this problem, we developed a system whereby she could pack the formula into gelatin capsules for ingestion. Packing and ingestion of 20 capsules required less than 30 minutes three times a day. With capsules her blood phenylalanine level was almost always within the recommended range of 120-360 mumol/L (2-6 mg/dl) and hospitalization was not required. The phenylalanine content of the capsules was easily accommodated by a small reduction in allowable food. Other amino acid levels, including tyrosine and other essential nutrient levels, were normal. We believe that using gelatin capsules for formula ingestion can be very beneficial in the management of maternal PKU pregnancies and could be extended to the dietary treatment of other inborn errors of metabolism.

Adult↗
PubMed1992

Comparison of phenylketonuric and nonphenylketonuric sibs from untreated pregnancies in a mother with phenylketonuria.

Two children, one with phenylketonuria (PKU) and the other nonphenylketonuric, from untreated pregnancies in a mother with PKU provided the opportunity to compare the degree of damage from maternal PKU between these genotypically different fetuses. Both the phenylketonuric offspring and her nonphenylketonuric sib were microcephalic at birth and had congenital anomalies, esophageal atresia in the former and congenital dislocation of the hip in the latter. However, the phenylketonuric child also had intrauterine growth retardation while the nonphenylketonuric sib had normal weight and length at birth. Both children are mentally retarded with an IQ below 50 in the phenylketonuric child despite early dietary treatment for PKU and an IQ of 54 in the nonphenylketonuric sib. Both children also have hypoplasia of the corpus callosum and enlarged cerebral ventricles. This experience and review of the literature indicates that the residual liver phenylalanine hydroxylase activity of a nonphenylketonuric fetus offers little or no protection from damage in untreated maternal PKU. Consequently, the outcome in maternal PKU is likely to depend on control of the maternal biochemical abnormalities in the mother regardless of whether the fetus has or does not have PKU.

Abnormalities, Multiple↗
PubMed1992

Molecular characterization of two galactosemia mutations and one polymorphism: implications for structure-function analysis of human galactose-1-phosphate uridyltransferase.

We report here the molecular characterization of two galactosemia mutations, L74P and F171S, and one polymorphism, S135L, in human galactose-1-phosphate uridyltransferase (GALT). Both galactosemia mutations result in reduced enzymatic activity when reconstructed in the cDNA and overexpressed. The polymorphism, in contrast, has near normal activity. Both mutations affect evolutionarily conserved residues, suggesting that they are functionally important, while the polymorphism occurs in a nonconserved domain which is presumably not critical for enzymatic function. The F171S mutation is close to the putative active-site nucleophile. Our data further support the notion of molecular heterogeneity of galactosemia and suggest that galactosemia mutations and GALT polymorphisms may be useful tools in highlighting different functional domains in human GALT.

Base Sequence↗
PubMed1992

Prenatal diagnosis of non-ketotic hyperglycinaemia.

Non-ketotic hyperglycinaemia (NKH) is a devastating neurological disease for which there is no effective therapy. Consequently, most couples with a pregnancy known to be at risk for NKH request prenatal diagnosis. We have applied the combination of chorionic villus (CVS) assay for glycine cleavage enzyme activity and determination of amniotic fluid glycine concentration to increase the reliability of prenatal diagnosis for this disorder beyond that of each of these methods alone. All 15 of the at-risk pregnancies monitored had CVS glycine cleavage assay and five also had amniotic fluid glycine measurements. Two cases had no detectable cleavage activity in CVS and one gave uninterpretable enzyme results. Amniotic fluid glycine concentration was increased in all three and NKH was confirmed by abortus tissue assays for cleavage activity and amino acids. The remaining 12 case had activity in CVS (two also had normal amniotic fluid glycine levels) and delivered unaffected infants. Four of these 12 cases had cleavage activities below or at the low end of the normal range, perhaps indicating carrier status. We believe that the combination of CVS glycine cleavage assay and amniotic fluid glycine measurement is currently the best approach to the prenatal diagnosis of NKH.

Amino Acid Metabolism, Inborn Errors↗
PubMed1992

Characterization of two missense mutations in human galactose-1-phosphate uridyltransferase: different molecular mechanisms for galactosemia.

We report the molecular characterization of two novel galactosemia mutations that exhibit different molecular phenotypes. Both are of the missense type with low or no residual enzyme activity. The R148W mutation results in an unstable protein, although messenger RNA is still produced. In contrast, the L195P mutation produces stable but inactive immunoreactive protein. The R148W mutation alters an amino acid that is not evolutionarily conserved, while the L195P mutation affects a well-conserved residue nine amino acids down-stream from the putative active site nucleophile. These mutations provide evidence that different mechanisms can result in galactosemia: destabilizing mutations in any given area of the protein and missense mutations in conserved domains of the enzyme resulting in low or no activity. These two mutant alleles represent the fifth and sixth galactosemia mutations and confirm the hypothesis that galactosemia results from a multiplicity of mutations at the molecular level.

Amino Acid Sequence↗
PubMed1992

Maternal phenylketonuria collaborative study, obstetric aspects and outcome: the first 6 years.

OBJECTIVE: The purpose of this study was to evaluate the efficacy of a phenylalanine-restricted diet in reducing fetal morbidity associated with maternal hyperphenylalaninemia in women of childbearing age with blood phenylalanine levels greater than 240 mumol/L (greater than 4 mg/dl) on an unrestricted diet. STUDY DESIGN: Two hundred thirteen pregnant women with hyperphenylalaninemia that resulted in 134 live births have been enrolled in the study. Outcome measures were subject to the chi 2 test, Fisher exact test, analysis of variance, t test, or Wilcoxon nonparametric test for analysis. RESULTS: Optimal fetal outcome appeared to occur when blood phenylalanine levels less than 600 mumol/L (less than 10 mg/dl) were achieved by 8 to 10 weeks' gestation and maintained throughout pregnancy (trimester averages of less than or equal to 360 mumol/L (less than or equal to 6 mg/dl). Initiation of dietary therapy during the third trimester of pregnancy appears to have little beneficial effect on the fetus. CONCLUSIONS: Preconceptual counseling and early entrance into a prenatal care program is essential in achieving optimal fetal outcome in women with hyperphenylalaninemia.

Congenital Abnormalities↗
PubMed1992

Intentional infantile ethylene glycol poisoning presenting as an inherited metabolic disorder.

A 6-month-old girl was hospitalized on three occasions for irritability, vomiting, acidosis, and hypotonia. During the third hospitalization hyperglycinemia and urinary glycolic acid were detected. Ethylene glycol was discovered in the infant's blood and bottled formula. Clinicians must consider ethylene glycol intoxication as a cause of recurrent infantile metabolic acidosis.

Acidosis↗
PubMed1991

Agoraphobia in phenylketonuria.

We describe agoraphobia as a complication of phenylketonuria (PKU) in young adults. The five patients have classic PKU and received phenylalanine-restricted diet only in childhood. Only one has normal intelligence. All but one were also depressed. All were anxious. Three of the five had initiated the phenylalanine-restricted diet after 3 months of age. Two returned to the phenylalanine-restricted diet with dramatic reduction of symptoms. The frequency of manifestations of agoraphobia was also examined in 50 young women with PKU enrolled in a longitudinal study of psychosocial factors in maternal PKU, 47 of their acquaintances and 49 women with diabetes. All were administered a test of agoraphobic-avoidant behaviour. The women with PKU appeared to be more prone to social withdrawal and fear of leaving home. Twenty per cent were within the agoraphobia range of the Mobility Inventory. Those still on diet and those with non-PKU hyperphenylalaninaemia reported less avoidant behaviour than those who had terminated the diet in childhood. These results suggest that young adults with PKU are at risk for agoraphobia but that return to the phenylalanine-restricted diet may be an effective treatment.

Adult↗
PubMed1991

Characterization of a novel biochemical abnormality in galactosemia: deficiency of glycolipids containing galactose or N-acetylgalactosamine and accumulation of precursors in brain and lymphocytes.

Classic galactosemia, an inborn error of human galactose metabolism, is characterized by a deficiency of the enzyme galactose-1-phosphate uridyltransferase (GALT). The current model for the pathophysiology of this disease ascribes most of its symptoms to the toxicity of intracellular galactose-1-phosphate (Gal-1-P), one of the substrates of GALT which accumulates in the untreated disease state. Recently, a reduction in the intracellular concentration of UDP-Gal (uridine diphosphogalactose), one of the products of GALT, has been described in treated galactosemic patients. We investigated whether galactosemic patients might also have reduced amounts of those macromolecules that depend on UDP-Gal for their biosynthesis. We report a reduction in glycolipids that contain either galactose or its derivative N-acetylgalactosamine and an accumulation of the precursors to these compounds in the brain of a neonate with galactosemia. We also found an imbalance in glycolipids in galactosemic lymphoblasts. This novel biochemical abnormality observed in galactosemic patients is not addressed by dietary galactose-restriction therapy and could explain some of the chronic neurologic and other complications of galactosemia.

Acetylgalactosamine↗
PubMed1991

Psychosocial factors in maternal phenylketonuria: prevention of unplanned pregnancies.

BACKGROUND: Women with phenylketonuria (PKU) not treated prior to conception can have a pregnancy that results in serious fetal damage. In this report, factors associated with preventing unplanned (and hence late treated) pregnancies are described. METHODS: Subjects included 60 phenylketonuric women and two comparison groups composed of female acquaintances and diabetic women. All were interviewed and administered tests of intelligence, general well-being, knowledge, and personality. RESULTS: Thirty-five percent of the sexually active women with PKU used contraception only sporadically. The variables that best predicted reported frequency of birth control use were the extent to which women felt social support to use contraception (r = .64) along with positive attitudes about birth control (r = .66) and knowledge of family planning (r = .43). For the comparison groups, a different pattern of variables predicted contraceptive use, with locus of control figuring most prominently for the diabetics (r = .39) and social support for birth control being most important for the acquaintances (r = .46). CONCLUSIONS: As more girls with PKU enter childbearing ages, there will be an increased need for specific programs that address psychosocial factors in maternal PKU.

Adolescent↗
PubMed1991

Histidase and histidinemia. Clinical and molecular considerations.

Histidase (histidine ammonia-lyase, EC 4.3.1.3) catalyzes the deamination of L-histidine to trans-urocanic acid in the liver and skin of mammals. Histidase deficiency results in increased histidine and histamine in blood, and decreased urocanic acid in blood and skin. In this review we discuss current research on: (1) the mechanism of formation of an unusual residue, dehydroalanine, at the active site of histidase; and (2) the role of urocanic acid as an ultraviolet light-induced immunoregulator in the skin, and the implications of urocanic acid deficiency for human histidinemia. Genetic mechanisms that may account for the 1% of histidinemic patients with neurological impairments are considered briefly.

Alanine↗
PubMed1991

Detection of phenylketonuria in the very early newborn blood specimen.

Early hospital discharge of newborns is leading to collection of the newborn screening blood specimen during the first day of life in increasing numbers of newborns. There is concern that neonates with phenylketonuria who are tested this early may be missed. To examine this question, the authors screened specimens collected during the first 24 hours of life from 23 neonates at risk for hyperphenylalaninemia. The blood phenylalanine level in each of the 6 neonates with phenylketonuria and a seventh with mild hyperphenylalaninemia was greater than 2 mg/dL as early as 4 hours of age and 6 mg/dL or greater by 24 hours of age. A newborn screening phenylalanine cutoff level of 2 mg/dL would have identified all of these neonates within the first 24 hours of life, but a cutoff level of 4 mg/dL would have missed 2 of the 6 with phenylketonuria before 24 hours of life. Newborn screening programs should adopt a blood phenylalanine level of 2 mg/dL as the cutoff for suspicion of phenylketonuria and request for a second specimen. Breast-fed affected neonates had higher early blood phenylalanine elevations than formula-fed neonates, perhaps reflecting the higher protein (phenylalanine) content of colostrum.

Bottle Feeding↗