The development of cystathionase activity during the first year of life

The development of hepatic cystathionase (EC 4.4.1.1) activity is dependent both upon the gestational age of the infant and the postnatal age. Full-term infants are born with greater hepatic cystathionase activity than pre-term infants, and the activity increases rapidly after birth reaching mature levels at about 3 months of age. Prematurely born infants have lower hepatic cystathionase activity at birth and like the full-term, the activity increases after birth. Cystathionase activity is not isolated to the liver. In both premature and full-term infants, it is present in the kidneys, and adrenals, but of little significance in the pancreas. These in vitro measurements of cystathionase activity indicate that the premature infant is potentially capable of endogenous cysteine production if provided with adequate methionine.

Intravenous nitrogen and energy intakes required to duplicate in utero nitrogen accretion in prematurely born human infants

In order to determine the intravenous energy and nitrogen intakes required to achieve intrauterine rates of nitrogen accretion and growth, 30 studies were completed in 22 premature infants who were provided with various intakes of amino acids and energy (glucose +/- lipid) by peripheral vein infusion. At constant nitrogen intake, increasing energy intake (as lipid) from 50 to 80 nonprotein kcal/kg/day resulted in significant increases in nitrogen retention and weight gain. Increasing nitrogen intake from 494 to 655 mg/kg/day at constant low energy intake (mean = 53 kcal/kg/day) had no effect on nitrogen retention or weight change; however, at higher energy intakes (mean = 81 kcal/kg/day) increasing nitrogen intake correlated significantly with increasing nitrogen retention. At energy intakes greater than 70 kcal/kg/day the major determinant of nitrogen retention was nitrogen intake. When energy intake was greater than 70 kcal/kg/day, the infusion of nitrogen providing 430 to 560 mg/kg/day (2.7 to 3.5 gm protein/kg/day) resulted in the duplication of intrauterine nitrogen accretion rates.

Cysteine supplementation to cysteine-free intravenous feeding regimens in newborn infants

To determine if cysteine is an essential amino acid for the intravenously fed newborn infant, growth parameters, nitrogen balance, plasma sulfur amino acid levels, and urinary amino acid excretion of premature and term infants were measured in the presence or absence of infused cysteine. Control intravenous formulations provided amino acids, including adequate methionine, carbohydrate, lipid, minerals, vitamins, and trace elements to all infants. Group and pair-matched comparisons showed that nitrogen retention, weight change, and growth in length and head circumference were not affected by cysteine supplementation of 77 mg/kg/24 h. The failure of cysteine supplementation to alter nitrogen retention was independent of postnatal age or gestational age. Plasma 1/2 cystine concentration was increased by 60% in the supplemented group with a concomitant 3-fold increase in urinary excretion of 1/2 cystine and taurine, but not of urinary methionine or cystathionine. Cysteine-supplemented infants exhibited a small increase in 3-methylhistidine excretion compared to pair-matched controls, suggesting that either an increase in muscle protein catabolism or an increase in muscle mass may have occurred.

Friedreich's ataxia with nephrotic syndrome and convulsive disorder: clinical and neurophysiological studies with renal and nerve biopsies and an autopsy

In a sibship of four, Friedreich's ataxia and minimal lesion nephrotic syndrome occurred in two siblings, a third sibling had Friedreich's ataxia, but no evidence of nephrotic syndrome; the fourth sibling had neither condition. The chance of Freidreich's ataxia and minimal lesion nephrotic syndrome occurring in two siblings is small, and suggested a common immunological abnormality. High dose prednisone and antimetabolites given for the nephrotic syndrome did not appear to affect the course of Friedreich's ataxia. The two siblings with Friedrich's ataxia and nephrotic syndrome developed epilepsy at age 15 years. All three children with Friedreich's ataxia had abnormal electroencephalograms (EEGs). These epileptiform EEG abnormalities were probably inherited from the mother, who had spike wave epilepsy. The neurologic deficits of Friedreich's ataxia, in turn, may have allowed the EEG trait to be expressed as a seizure disorder. The progressive ataxia and epileptic, sometimes myoclonic, seizures in these patients and the dentate nucleus changes in the autopsied patient were consistent with the diagnosis of dyssynergia cerebellaris myoclonica. This suggested that the latter disorder may represent a coincidence of two genetic entities: Friedreich's ataxia and spike wave epilepsy.