Steven P. Segal

Learn More
In the early 1950's, Harris, Mittwoch, Robson, and Warren (1, 2) investigated the mode of inheritance of cystinuria in 27 families by using quantitative determinations of cystine and dibasic amino acids as the genetic marker. Homozygotes were identified by the formation of urinary tract calculi composed of cystine and by gross hyperexcretion of cystine,(More)
Despite restricted ingestion of lactose, patients with galactose-1-phosphate uridyltransferase deficiency have raised concentrations of galactose metabolites in blood and urine. Endogenous production of galactose may underlie this phenomenon. Using isotopically labelled galactose in a continuous intravenous infusion, we employed the steady-state flux method(More)
Uptake of L-proline and glycine by rat renal brushborder membrane vesicles was seen to be osmotically sensitive, pH dependent,and occurred in the absence of proline and glycine metabolism. The uptake system for proline was Na+ gradient dependent, and exhibited a dual system for entry, Km1 = 0.067 mM and Km2 = 5.26 mM. The uptake of glycine was also Na+(More)
ABSTRACT: To assess the role of genetic regulation as a modulating factor in the variability of rat tissue galactose-1-phosphate uridyltransferase (GALT) sp act, we have determined steady state GALT mRNA and sp act in rat liver during postnatal development. Steady state GALT mRNA levels increase from birth to d 5 and subsequently decrease toward adult(More)
OBJECTIVE The study examined whether the prescription practices of clinicians in psychiatric emergency services differed for African-American patients. Prescription of antipsychotic medications and its relation to quality of care was a particular focus. METHODS Data from 442 independently observed evaluations of patients in psychiatric emergency services(More)
The uptake of cystine by vesicles prepared from rat kidney brush borders occurs by two distinct transport systems. The higher affinity system is inhibited by the dibasic amino acids lysine, arginine, and ornithine. The lower affinity system, unaffected by dibasic amino acids, appears to correspond to that observed by studying uptake of cystine by kidney(More)
Uptake of L-cystine by brush-border membrane vesicles isolated from rat renal-cortical tissue was time-dependent and occurred in the absence of cystine reduction. A significant capacity for vesicular binding of cystine was observed. The amount bound increased with time of incubation and could be displaced by thiol reagents. At early time points, cystine(More)
We report a controlled study of intellectual outcome in 16 children with maple syrup urine disease (MSUD) that compares the outcome of MSUD diagnosed after symptoms became apparent with that of MSUD diagnosed prospectively and in unaffected siblings and parents. The mean IQ (+/- SD) score in the children with classic MSUD was 78 +/- 24; however, there were(More)
The effect of cystine dimethylester on the renal handling of phosphate, glucose, alpha-amino nitrogen, amino acids, and protein in vivo and on the uptake of lysine, glycine, taurine, and alpha-methyl glucoside by isolated renal tubules in vitro was studied in adult male rats. Parenteral administration of 400 mumol twice a day for four days of cystine(More)
We have developed a sensitive method that employs high-performance liquid chromatography to separate and quantitate uridine diphosphogalactose (UDPGal) and uridine diphosphoglucose (UDPGlu) in human red blood cells. The trichloracetic acid extracts of red blood cells were chromatographed using a Dionex CarboPac anion-exchange resin and a 20-40% potassium(More)