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Biomedical subjects

S D Cederbaum

Publications and source records attributed to S D Cederbaum.

At least 19 recordsLinked to original sources
PubMed1992

The pathobiochemistry of uremia and hyperargininemia further demonstrates a metabolic relationship between urea and guanidinosuccinic acid.

To better understand the biosynthesis of guanidinosuccinic acid, we determined urea, arginine, and guanidinosuccinic acid levels in nondialyzed uremic and hyperargininemic patients. These substances were also determined during several years of therapy in one hyperarginiemic patient. Interrelationships of guanidinosuccinic acid levels with their corresponding urea and arginine levels were assessed by linear correlation studies. In uremic patients, a significant positive linear correlation (r = .821, p less than .001) was found between serum urea and guanidinosuccinic acid levels A significant positive linear correlation was also found between serum urea levels and urinary guanidinosuccinic acid levels (r = .828, P less than .001), but not between serum arginine levels and urinary guanidinosuccinic acid levels in hyperargininemic patients. In the intrahyperargininemic patient study, a similar significant positive correlation was found between serum urea levels and the corresponding urinary guanidinosuccinic acid levels (r = .866, P less than .001); the correlation between serum arginine levels and the corresponding urinary guanidinosuccinic acid levels was smaller. The presented analytical findings in uremic and hyperargininemic patients clearly demonstrate a metabolic relationship between urea and guanidinosuccinic acid.

Adult↗
PubMed1992

Deletion in blood mitochondrial DNA in Kearns-Sayre syndrome.

Mitochondrial DNA deletions have been described in the Kearns-Sayre syndrome (KSS) and the Pearson's marrow-pancreas syndrome. In some cases, the same 4,977-bp deletion has been identified in these two very different diseases. Therefore, it is not currently possible to predict the clinical phenotype from the size or location of the deletion. Instead, differential tissue distribution of the deletion has been implicated as one possible determinant of phenotype. In particular, in KSS the deletions have not been detected by Southern blotting in the blood, whereas in Pearson's syndrome they are easily detectable. We describe here an 11-y-old boy with clinically characteristic KSS and a 7.4-kb mitochondrial DNA deletion between nucleotides 7,194 and 14,595. Southern blotting reveals that 75% of the mitochondrial DNA molecules from his peripheral blood have this deletion. This case blurs further the molecular distinction between the KSS and Pearson's marrow-pancreas syndrome, questioning whether tissue distribution is a sufficient explanation for the very different phenotypes of these disorders.

Anemia, Sideroblastic↗
PubMed1991

Effect of an adjacent base on detection of a point mutation by restriction enzyme digestion.

While routinely mapping point mutations within the arginase locus of a collection of hyperargininemic patients, we discovered that a base immediately outside a restriction endonuclease recognition site (TaqI) can eliminate cleavage of this site by this enzyme. The genetic lesion lay in a base immediately flanking a TaqI recognition site within exon 8 of the arginase locus and abolished cutting by approximately 80%. We wish to emphasize the necessity of heeding subtle cues frequently encountered while generating restriction enzyme data, because neither Southern blot maps nor endonuclease digestion of polymerase chain reaction amplified products of exon 8 accurately predicted where the point mutation lay. To our knowledge, this is the first instance of inhibition of cleavage by flanking bases occurring on natural (nonsynthetic) DNA substrates, i.e., within the clinical setting of characterization of a human genetic disorder.

Base Sequence↗
PubMed1990

Guanidino compound analysis as a complementary diagnostic parameter for hyperargininemia: follow-up of guanidino compound levels during therapy.

The aim of this collaborative study was to investigate whether guanidino compound analyses in the biologic fluids can be used as a complementary diagnostic parameter for hyperargininemia. Guanidino compounds were determined in the biologic fluids of all known living hyperargininemic patients using a cation exchange chromatographic system with a fluorescence detection method. The serum arginine, homoarginine, alpha-keto-delta-guanidino-valeric acid, argininic acid, and N-alpha-acetylarginine levels of all the hyperargininemic patients are higher than the normal range. Similar increases were seen for the urinary excretion of alpha-keto-delta-guanidinovaleric acid and argininic acid. Untreated hyperargininemic patients have the highest guanidino compound levels in cerebrospinal fluid. However, even under therapy, the arginine, homoarginine, alpha-keto-delta-guanidinovaleric acid, and argininic acid levels in cerebrospinal fluid are still increased. Protein restriction alone is not sufficient to normalize the hyperargininemia, but protein restriction together with supplementation of essential amino acids with or without sodium benzoate decreases further the arginine levels. However, whereas the argininemia can be normalized, the catabolites of arginine are still increased. We conclude that the urinary amino acid levels may remain normal in hyperargininemia, whereas consistent increases of the guanidino compounds are observed. Thus, guanidino compound analyses can be used as a complementary biochemical diagnostic parameter for hyperargininemia. Although the argininemia can be normalized by therapy, the levels of the catabolites of arginine are still elevated.

Adolescent↗
PubMed1989

Parenteral nutrition in propionic and methylmalonic acidemia.

Although propionic acidemia and methylmalonic acidemia, two disorders of branched-chain amino acid metabolism often complicated by chronic anorexia and vomiting, are not usually treated with parenteral nutrition for fear of amino acid overload and exacerbation of biochemical derangements, we gave long-term parenteral nutrition to two critically ill patients with these disorders. Health and growth were restored, and there was minimal production of abnormal metabolites. The dramatic clinical and biochemical improvement of these patients bolsters the concept that most of the toxic metabolites produced in these diseases are not related to the administered load of nutrient precursors, but rather to endogenous turnover of amino acids, particularly during a chronic catabolic state. Suppression of catabolism can produce striking biochemical and clinical improvement. With appropriate monitoring, parenteral nutrition can be used safely in the management of patients with these disorders.

Amino Acid Metabolism, Inborn Errors↗
PubMed1979

Hyperlysinemia with saccharopinuria due to combined lysine-ketoglutarate reductase and saccharopine dehydrogenase deficiencies presenting as cystinuria.

A 7-year-old boy with speech delay, hyperactive behavior, and minor neurologic abnormalities had been found in the past to have "intermittent cystinuria." A more detailed investigation revealed hyperlysinemia and hyperlysinuria, with lesser increases in urinary excretion of arginine and cystine. The plasma and urine abnormalities increased on a diet of 3 gm of protein/kg body weight/day. Saccharopine, a normal metabolite of lysine not found in the body fluids of normal people, was present in plasma, cerebrospinal fluid, and urine of the patient. Lysine-ketoglutarate reductase and saccharopine dehydrogenase activities were not detectable in extracts of cultured skin fibroblasts. Re-examination of the urine of previously studied cases of this double enzyme deficiency suggests that saccharopinuria of variable degree is the rule and not the exception.

Cells, Cultured↗
PubMed1979

Adsorption of organic acids from amniotic fluid and urine onto silica gel before analysis by gas chromatography and combined gas chromatography/mass spectrometry.

We describe a method for adsorbing organic acids from amniotic fluid and urine specimens onto a column of silica gel before analysis by gas chromatography and by combined gas chromatography/mass spectrometry. Analytical recoveries of individual organic acids by our adsorption method compare favorably with those obtained by a more laborious manual extraction with ethyl acetate. Results for specimens of amniotic fluid and urine show that our method gives better recoveries of most of the organic acids. Furthermore, because citric acid is also extracted in our method without extracting significant amounts of sulfate or phosphate, the method is a suitable alternative to methods involving the use of DEAE-Sephadex for concentrating these acids.

Amniotic Fluid↗