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Biomedical subjects

J Dancis

Publications and source records attributed to J Dancis.

At least 55 records · Page 3Linked to original sources
PubMed1983

The prognosis of hyperlysinemia: an interim report.

Ten patients with familial hyperlysinemia with lysine-ketoglutarate reductase deficiency, identified through newborn screening programs or family surveys, were selected for review. Ages ranged from 2 to 24 years when last examined. A low-protein diet had been administered to two patients, which reduced the plasma lysine levels from 20 mg per dl or more to about 12 mg per dl. The rest were untreated. Mental development was judged normal or above average in nine. Mildly subnormal performance in three was considered appropriate to family and social background. No adverse mental or physical effects could be attributed to the hyperlysinemia. A normal child has been born to a mother with hyperlysinemia, indicating that the fetus may develop normally despite exposure to high lysine levels.

Adolescent↗
PubMed1982

Comparative rates of metabolism of pipecolic acid in several animal species.

1. The rate of metabolism of pipecolic acid, measured in liver and kidney, varied 1000 fold among 10 animal species. Degradation of L-pipecolic acid by kidney in rat and mouse was 0.11 and 0.31 pmoles/min/mg protein, respectively; in monkey and human. 3.0 and 6.5; in guinea-pig and rabbit 101 and 106. 2. Activity with D-pipecolic acid was consistently 50-60% higher than the L-isomer except in the rabbit. 3. Degradation of L-lysine presumably through the saccharopine-alpha-aminoadipic acid pathway, was effective in all species, contrasting with the variable performance in the pipecolic acid-alpha-aminoadipic acid pathway.

Animals↗
PubMed1981

Transfer of urea, sodium, and chloride across the perfused human placenta.

Clearance indices (clearance of experimental material: clearance of antipyrine, CI) across the perfused human placenta were determined for urea, sodium, and chloride. The selected materials are of relatively small molecular weight and are water soluble. Clearance of urea was determined under conditions of net transfer and of exchange and no difference was detected. Sodium and chloride clearances were measured as exchange rates. The CI were: urea, 0.32 and 0.38 toward fetus and mother, respectively); sodium, 0.28; and chloride, 0.41 (measured toward the fetus). Recalculation of data as the diffusion limitation (LD) facilitated comparison with data in the literature on the monkey, rabbit, and sheep. LD for urea was comparable among the four species whereas the sheep placenta differed, sharply limiting the diffusion of sodium and chloride. The discrepancy in the sheep between urea and sodium indicates that the low transfer rate of the latter cannot be explained by the "thickness" of the syndesmochorial placenta, as is often stated. Inferences concerning nitrogen metabolism in the fetus have been derived by others from data on transplacental urea gradients and urea clearance. Available data in the human are incomplete but are consistent with amino acids providing approximately 10% of fetal energy needs, with glucose serving as the predominant substrate.

Animals↗
PubMed1981

The metabolism of D- and L-pipecolic acid in the rabbit and rat.

The metabolism of D- and L-pipecolic acid has been investigated in rabbits and rats. A rapid evolution of 14CO2 followed the injection of either D- or L-pipe[6-14C]colic acid into rabbits. Rabbit kidney slices degraded to CO2 both isomers of lysine and of pipecolic acid. Rabbit liver was effective with only the L-isomers. In the rat, very little of injected L-pipecolic acid was catabolized to CO2, and large amounts were excreted unchanged into the urine, L-Lysine was efficiently metabolized to CO2 by rat liver and kidney slices but not D-lysine or either isomer of pipecolic acid. Rat kidney converted D-lysine to L-pipecolic acid. The L-isomer was identified by co-precipitation of the radioactive product with authentic compounds.

Amino Acids↗
PubMed1980

Placental transfer of steroids: effect of binding to serum albumin and to placenta.

The transfer rates and placental retention of a series of steroids were measured using an in vitro perfusion system of an isolated cotyledon of human placenta. The steroids were added to the maternal inflow and rates of appearance in maternal and fetal outflows were measured, from which data were calculated the transfer rate and placental retention. With a low concentration of albumin (0.01 g/dl) in the maternal and fetal perfusates, transfer rates of diethylstilbestrol and ethynylestradiol were initially low, with considerable retention of the steroids within the placenta. Transfer rates increased with duration of perfusion. With high concentrations of albumin (1 g/dl), placental retention was greatly reduced and transfer rates very rapidly reached high levels. Albumin in the fetal circulation was the effective factor in increasing transfer rate; maternal albumin reduced it. The results with estrone and progesterone were qualitatively similar but not as striking, posssibly because of the large endogenous concentrations of these two hormones. Placental retention of dexamethasone, a more polar steroid that does not bind to placenta and binds poorly to albumin, was low and there was little difference between transfer from low- and high-protein perfusates.

Biological Transport↗
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

Secretory proteins in the perfused human placenta.

A relatively simple perfusion technique of human placenta has been applied to the study of secretory proteins. Preferential secretion into the maternal circulation of human chorionic gonadotropin (HCG), human chorionic somatomammotropin (HCS), follicle-stimulating hormone (FSH), and placental alkaline phosphatase has been demonstrated, contrasting with the bidirectional secretion of progesterone. Evidence is presented for the net synthesis of HCS during perfusion. The technique offers advantages in the study of synthesis and secretion of placental materials.

Alkaline Phosphatase↗
PubMed1979

Familial hyperlysinemia: enzyme studies, diagnostic methods, comments on terminology.

Enzyme assays of skin fibroblasts from five children with familial hyperlysinemia from unrelated families are added to the previous report of three children from two unrelated families. In all instances there was a deficiency in lysine-ketoglutarate reductase, saccharopine dehydrogenase, and saccharopine oxidoreductase activities. To complete the studies on the enzymes associated with familial hyperlysinemia, saccharopine oxidoreductase was partially purified from human liver and characterized. The activity did not separate from that of lysine-ketoglutarate reductase or saccharopine dehydrogenase. A simple screening test for familial hyperlysinemia is described based on the evolution of 14CO2 from lysine-14C by skin fibroblasts. The test differentiated, without overlap, seven patients with familial hyperlysinemia from control subjects. The relation of the two genetic entities involving lysine degradation, familial hyperlysinemia and saccharopinuria, is discussed. It is suggested that familial hyperlysinemia, type I, be applied to patients with major defects in lysine-ketoglutarate reductase and saccharopine dehydrogenase, and that familial hyperlysinemia, type II, to be used to designate patients in whom significant amounts of lysine-ketoglutarate reductase are retained. The nomenclature would be consistent with that of an analogous disease, orotic aciduria.

Amino Acid Metabolism, Inborn Errors↗
PubMed1978

The transfer and metabolism of corticosteroids in the perfused human placenta.

The transfer and metabolism of cortisol, prednisolone, betamethasone, and dexamethasone were investigated in vitro in the perfused human placenta. Maternal and fetal circuits were established but the steroid was added to the former only. The clearance expressed as a fraction of the antipyrine transfer rate varied from 0.27 to 0.50, but there were no significant differences among the four steroids. All the steroids were metabolized extensively to their respective 11-ketosteroids and again there were no material differences among the steroids. The metabolic conversions of dexamethasone and betamethasone were far greater in the perfused placenta than in minced placenta. From the standpoint of placental transfer and metabolism, as observed in the perfusion studies, none of the four corticosteroids offers a decisive advantage in the antepartum maturation of the fetal pulmonary surfactant system.

Antipyrine↗