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Biomedical subjects

S E Snyderman

Publications and source records attributed to S E Snyderman.

At least 19 recordsLinked to original sources
PubMed1997

Newborn screening for homocystinuria.

It is becoming increasingly apparent that pyridoxine responsive homocystinuria patients are being missed by newborn screening programs. The possibility that screening for homocystine, rather than the methionine, might be more effective was investigated by comparing homocystine and methionine levels of non-responsive patients at diagnosis. The plasma methionine levels of 11 infants were much more abnormal than the homocystine levels. Urine homocystine was low or not detectable and always less than methionine. Therefore, methionine determination is much more effective than homocystine determination for newborn screening for homocystinuria. It seems that a second blood specimen at a later age may be required to find the pyridoxine responsive infants.

Homocystine↗
PubMed1995

Molecular basis of phenotypic variation in patients with argininemia.

Argininemia is an autosomal recessive disorder caused by a deficiency in the liver-type arginase enzyme. Clinical manifestations include progressive spastic diplegia and mental retardation. While the quality of life can severely deteriorate in most such patients, some do show remarkable improvement in neurological symptoms while on controlled diets. We examined the thesis that differences in clinical responses to dietary treatment are based on molecular heterogeneity in mutant arginase alleles. Genomic DNAs from 11 patients with argininemia were examined using the polymerase chain reaction, cloning, and sequencing. Nine mutations representing 21/22 mutant alleles were identified in 11 patients with argininemia, and four of these mutations were expressed in vitro to determine the severity of enzymatic defects. We found that these mutations accounted for 64% of the mutant alleles in our patients. Based on findings in vitro expression tests, the mutations can be considered either severe or moderate. Patients with at least one moderate mutant allele responded well to dietary treatment; concentrations of plasma arginine were controlled within 300 microM. In contrast, patients with two severely mutated alleles did not respond to dietary treatment and plasma arginine was over 400 microM. Argininemia is heterogeneous at the molecular level. The degree of clinical improvement during dietary treatment is reflected in the concentration of arginine in plasma, as a measure of metabolic control. Plasma arginine levels during treatment is reflected in the concentration of arginine in plasma, as a measure of metabolic control. Plasma arginine levels during treatment correlated with types of molecular defects in the arginase genes.

Alleles↗
PubMed1995

Baclofen in the treatment of polymyoclonus and ataxia in a patient with homocystinuria.

A patient with homocystinuria due to cystathionine beta-synthase deficiency developed severe progressive polymyoclonus and ataxia. To our knowledge, this is the first time polymyoclonus and ataxia have been reported in association with homocystinuria. Although cerebrovascular thrombosis is usually thought to be responsible for neurologic dysfunction in homocystinuric patients, no infarctions were demonstrated on magnetic resonance imaging scans in our case. We have previously reported that baclofen dramatically improved the polymyoclonus and ataxia in a patient with Unvericht-Lundborg disease. Baclofen given to our patient reversed the polymyoclonus and the ataxia as well. This suggests that patients with polymyoclonus and ataxia, no matter what the etiology, may benefit from the use of baclofen.

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↗
PubMed1987

Successful long term therapy of biopterin deficiency.

A hyperphenylalaninaemic infant, started on dietary therapy at 14 days of age, had severe developmental retardation and neurological abnormalities despite excellent biochemical control. A diagnosis of a deficit in biopterin synthesis was made at five months of age as a result of the following: high neopterin and low biopterin levels in both blood and urine, normal dihydropteridine reductase in the liver and a sharp drop in the plasma phenylalanine level 4 h after the administration of a test dose of tetrahydrobiopterin. Treatment with levodopa, carbidopa and 5-hydroxytryptophan resulted in prompt neurological improvement. This was followed by gradual and sustained development. At present, at the age of 7 years, the child is mentally and physically normal.

5-Hydroxytryptophan↗
PubMed1984

The relationship between the branched chain amino acids and their alpha-ketoacids in maple syrup urine disease.

Plasma branched chain amino acid levels and their respective ketoacid analogues were determined in seven maple syrup urine disease patients ranging in age from 12 h to 12 years. One hundred one pairs were analyzed. There was a high degree of correlation between the amino acid and its ketoacid analogue at every amino acid level. The coefficient of correlation (0.84) was highest for leucine-alpha-ketoisocaproic acid. The ratio of ketoacid analogue to amino acid, (0.87), was also the greatest for leucine. The close correlation implies that adequate monitoring for therapy can be accomplished by the use of the technically simpler and more rapid determination of the plasma branched chain amino acids.

Amino Acids, Branched-Chain↗
PubMed1982

Disseminated ulcerations in allergic eosinophilic gastroenterocolitis.

An infant with allergic eosinophilic gastroenterocolitis is described. The patient presented with vomiting, diarrhea, gastrointestinal bleeding, and failure to thrive. Anemia, hypoproteinemia, and peripheral eosinophilia were also present. Gastrointestinal endoscopy revealed multiple mucosal ulcerations in the stomach, small intestine, and colon. Histological study of the affected areas showed infiltration of the mucosa by eosinophils, increased mucosal IgE plasma cells, and activated intraepithelial lymphocytes. Treatment with corticosteroids resulted in clinical and histological remission.

Child, Preschool↗
PubMed1981

Plasma and cerebrospinal fluid amino acid concentrations in phenylketonuria during the newborn period.

Plasma and cerebrospinal fluid amino acid values were determined in 29 infants 9 to 30 days of age with a confirmed diagnosis of phenylketonuria. Phenylalanine concentrations in plasma and cerebrospinal fluid were markedly elevated; the degree of elevation in the cerebrospinal fluid had a significant relationship to that of the plasma. The only other significant deviations in the plasma were reductions in the threonine and tyrosine values. Cerebrospinal fluid threonine, alanine, and arginine concentrations were reduced, whereas those of serine, isoleucine, and histidine were elevated. This combined deficiency and excess of amino acids in the central nervous system may have a significant effect on protein synthesis at a time in life when this synthesis and turnover is most active.

Amino Acids↗
PubMed1979

The nutritional therapy of histidinemia.

Control of the plasma histidine level in histidinemia is possible with the use of an amino acid mixture free of histidine and a carefully monitored intake of histidine. This regimen is compatible with good physical growth and normal mental development. If further clinical experience demonstrates that widespread nutritional intervention in this disease is warranted, it should be possible to obtain good biochemical control.

Adolescent↗
PubMed1979

The thrombogenicity of 6-azouridine.

The antimetabolite 6-azauridine blocks the de novo synthesis of pyrimidines and causes increased serum levels of several amino acids including homocystine. 6-Azauridine was was withdrawn from clinical use for the treatment of psoriasis because of the occurence of arterial and venous thromboembolic episodes in some psoriatic patients. Utilizing a standard animal model for the recognition of venous and arterial thrombosis, 6-azauridine was demonstrated in this study to cause thrombosis without producing homocystinemia when administered orally or intravenously.

Administration, Oral↗
PubMed1977

Argininemia.

The clinical features of argininemia in two cousins included hyperactivity, spasticity, ataxia, retardation, and repeated attacks of hyperammonemia. Study of a large kindred suggests that arginase-deficiency is transmitted as a Mendelian recessive. Treatment with an essential amino acid mixture with the total nitrogen intake limited to the requirement, controlled the hyperammonemia, reduced the plasma arginine level, and permitted a marked clinical improvement. There has been a significant increase in intelligence levels; the previously retarded children are now approaching the normal range of function.

Amino Acid Metabolism, Inborn Errors↗