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Background:Stimulation of the nervous system plays a central role in brain development and neurodevelopmental outcomes. Thalamocortical and corticocortical development is diminished in premature infants and correlated to electroencephalography (EEG) progression. The purpose of this study was to determine the effects of orocutaneous stimulation on the modulation of spectral edge frequency fc= 90% (SEF-90), which is derived from EEG recordings in preterm infants.Methods:A total of 22 preterm infants were randomized to experimental and control conditions. Pulsed orocutaneous stimulation was presented during gavage feedings begun at ~32?wk postmenstrual age. The SEF-90 was derived from two-channel EEG recordings.Results:Compared with the control condition, the pulsed orocutaneous stimulation produced a significant reorganization of SEF-90 in the left (P = 0.005) and right (P < 0.0001) hemispheres. Notably, the left and right hemispheres showed a reversal in the polarity of frequency shift, demonstrating hemispheric asymmetry in the frequency domain. Pulsed orocutaneous stimulation also produced a significant pattern of short-term cortical adaptation and a long-term neural adaptation manifested as a 0.5 Hz elevation in SEF-90 after repeated stimulation sessions.Conclusion:This is the first study to demonstrate the modulating effects of a servo-controlled oral somatosensory input on the spectral features of EEG activity in preterm infants.

Extract: Urea cycle function was evaluated in liver obtained from six patients with Reye's syndrome and from five control subjects. Reye's syndrome patients demonstrated normal activities for the extramitochondrial portion of the urea cycle, but showed marked abnormalities of the mitochondrial enzymes, i.e., carbamyl phosphate synthetase (CPS) and ornithine transcarbamylase (OTC) (Tables 2, 3). CPS activity was reduced to less than 15% of control values in all four patients from whom tissues was obtained during the first 72 hr after the onset of encephalopathy. Two patients from whom tissue was not obtained until after 9 days of symptoms showed no reduction in CPS activity. The OTC activity was also reduced (3–67% of control values) in the four patients from whom tissue was obtained early in the illness. In addition, greater than 60% reduction in Vmaxand Kmfor carbamyl phosphate was noted in all four patients in whom sample size permitted kinetic analysis, including both patients in whom CPS and OTC activity were not markedly reduced. The same kinetic abnormality as well as decreased CPS activity were experimentally produced in normal rat liver incubated in the presence of 1.0 mM 4-pentenoic acid, a short chain fatty acid and known hepatic mitochondrial toxin (Table 4).Speculation: Abnormalities of the mitochondrial portion of the urea cycle are a frequent occurrence in Reye's syndrome. This appears to be an acquired and reversible process that can probably be produced by a number of etiologic agents, of which endogenous or exogenous short chain fatty acids may be included.

Extract: We have described a patient with ornithine transcarbamylase (OTC) deficiency. The clinical course and pedigree substantiate the X-linked transmission of the defect with varying degrees of illness in females. Because orotic aciduria accompanied hyperammonemia in the patient, orotic acid was measured as an indication of a partial OTG deficiency after ammonia and protein loading in members of the patient's family. Both the mother, an obligate carrier, and an aunt, the only symptomatic female in this pedigree, had hyperammonemia after the ingestion of ammonium chloride. They also had significant orotic aciduria after a protein load as did the two female cousins whose ammonium tolerance was normal. The maternal grandmother excreted a large amount of orotic acid in her urine relatively consistently. These data suggest that the two female cousins and the maternal grandmother are asymptomatic female heterozygotes despite their normal ammonium loading tests.Speculation: Protein loading in the form of a relatively palatable and innocuous meal, followed by determination of orotic acid content in urine, may prove to be a sensitive, noninvasive, and easy means to identify female carriers of ornithine transcarbamylase deficiency.

Extract: At 15 days after birth, the small intestine of the rat showed a striking increase in relative weight, an increased depth of intestinal crypts, an elevation of the mitotic and the labeling index of crypt cells, and a decrease in the ratio of height of the villi to depth of the crypts.Metabolically, the biological half-life of 14C phenylalanine incorporated into protein was decreased in the intestine of 21-day-old rats compared with that of the 32-day-old rat. With autoradiography, a decreased half-life of 3H-leucine in crypt cells was noted in rats 5 and 21 days of age, compared with fully weaned rats 32 days of age. These observations indicated that protein turnover is not completely dependent on cellular turnover in suckling rats.Artificial feeding of suckling rats from 9 to 15 days of age produced an increase in the relative weight, mitotic index, depth of crypts, and activity of invertase in the jejunum. Prolonged administration of hydrocortisone to newborn rats resulted in similar changes in the duodenum and in the jejunum, but not in the ileum. These changes could be related to an increased rate of cellular migration along the villi of the duodenum and the jejunum. It was concluded that both diet and hormones were important factors in the marked changes in intestinal cell proliferation and differentiation observed at weaning.Speculation: The usual changes in cellular proliferation and differentiation of the intestinal mucosa of the weanling rat and the observation that these changes can be stimulated precociously suggest that the intestinal tract of suckling rats could be used to investigate further those factors important to the control of cell differentiation. Since cell turnover increases to adult levels after 15 days of age, the observed increase in protein turnover in suckling and in weanling rats, compared with that of adult rats, suggests that at these ages protein turnover is not coordinated with cell turnover.

Ritodrine hydrochloride (RH) is a β-adrenergic, tocolytic agent. RH activates adenyl cyclase which generates cyclic adenosine monophosphate (cAMP). cAMP is reported to increase hepatic heme oxygenase (HO) activity. Because increased hepatic HO activity has been associated with increased hepatic early-labeled bilirubin (ELB) production, we studied the effect of RH on total bilirubin formation (TBF). Litters of Wistar rats (< 12 hrs old) were divided into groups (3 rats each) of equal weight and given 2 SQ injections of RH (35 mg/kg) or saline at 7 and 5 hrs prior to injection of a radio-labeled hepatic heme precursor, δ-ALA-5-14C (0.6 μCi/12.3 nmol) (t=0). 14CO was collected continuously and was quantitated at t=1, 2, 3, 4, 6, 8, and 12 hrs. The excretion rate of carbon monoxide (VeCO), an index of TBF, was determined at t=0, 2, 4, 6, 8, and 12 hrs. At t=12 hrs, the animals were decapitated and blood and liver were collected. Plasma bilirubin (mg/dl) was measured by a UB Analyzer and HO activity(nmoles bili/min/10 mg prot) was determined spectrophotometrically.Our results suggest that, although high dose RH administration in rats increases hepatic HO activity and ELB, these changes are minimal and the effect of RH on TBF is small.

The enteric epithelium of the suckling rat undergoes dramatic functional and cytokinetic changes at the time of weaning. Evidence suggesting that this redifferentiation is preprogrammed and intrinsic has been obtained by surgical transplants of fetal intestines. In an attempt to alter this redifferentiation a 60% proximal intestinal resection was performed on suckling rats at 10 days of age. Animals surviving for 2 months were compared with sex and weight matched littermates who had undergone laparotomy or laparotomy with transection. The residual intestine was increased in diameter and weight per unit length, but not significantly lengthened. The segmental increase in weight was primarily accomplished by hyperplasia as evidenced by parallel increases in total protein and DNA content. This increase in cell number was associated with a modest increase in the segmental sucrase and maltase activities in the residual ileum. However, when expressed as activity per unit DNA, sucrase and maltase concentrations in the residual ileum were indistinguishable from control ileal segments. Lactase activity virtually disappeared from all segments of the residual intestine in resected animals. These results lend in vivo support to the concept of a fixed intrinsic program of enteric redifferentiation.

The brush border membrane of the immature rat intestine contains lactase and maltase as the predominant sugar hydrolases, through the suckling period of the animal. These enzymes were isolated in high purity (lactase S.A. 23, maltase S.A. 58) from infant rat intestine and monospecific antisera (rabbit) were prepared to each. Brush border membranes from 15-day old rats were isolated in excess of 25-fold purification (using lactase as a membrane marker enzyme) by procedures yielding membranes at 2 to 3-fold greater purity from infant rat intestine than reported previously (Galand and Forstner, Biochem.J.(1974)144:293).Incubation of brush border membranes with anti-maltase and anti-lactase resulted in binding of each antibody in stoichiometric equivalence to that obtained with the respective pure enzyme. Thus, it could be concluded that each of the sugar hydrolases exist on the membrane fully exposed and equally available to antibody as is the free enzyme in solution. Furthermore, the binding of antibody to one did not affect the immuno-titration curve of the other nor its extractability by papain or Triton X-100. Each of the sugar hydrolases, therefore, is a brush border membrane surface component, which is independently placed in relation to the other and arranged so that its unique antigenic determinants are fully available for immunoreactivity.(Supported by N.I.H. grants HD-49, HD-02147, HD-00391, CA-14917.)

The recently developed technique of gas chromatography (GC) - mass spectrometry (MS) - supported by computer has considerably improved the analysis of physiologic fluids. This study attempted to demonstrate the value of the GC-MS-computer system in the investigation of urinary metabolite patterns in two metabolic problems of prematurity, viz, transient tyrosinemia and late metabolic acidosis. A total of 124 24-hours urine specimens were analyzed in 9 infants. Transient tyrosinemia, characterized by 5-10 fold increases over basal excretion of urinary tyrosine, p-OHphenyllactate and p-OHphenylpyruvate, was noted in 5 of the infants. Several infants had fluctuating levels of urinary tyrosine metabolites although dietary protein intake remained constant at 3-4 gm/kg/day and ascorbic acid at 50 mg/day. Sporadic testing can understimate the actual incidence of transient tyrosinemia. Late metabolic acidosis was seen in 4 infants, but bore no relation to transient tyrosinemia. The ratio of urinary net acid to urea excretion increased with increasing base deficit, implying a non-protein origin of the metabolic acid. No unique metabolic patterns were characteristic of late metabolic acidosis. The use of GC-MC-computer systems is a promising technique for metabolic studies of premature infants.

High molecular weight precursor forms of various intestinal brush border enzymes have been demonstrated by pulse-labelling of intestinal explants maintained in culture. In the present study we have examined in vivo precursor forms of rat intestinal lactase. Fasted infant rats were injected (IP) with [35S]-methionine and killed after 0.5, 2, 4, and 18 H. The short fast was necessary to maximize incorporation of label. Lactase forms were isolated from Triton X-100 extracts of the intestinal homogenates by immunoprecipitation techniques using highly selective antisera. The isolated enzyme forms were separated by SDS-electrophoresis and examined by fluorography. Labelling within 30 min occurred in precursor forms of apparent mol. wts of 170, 125, and 90 Kd. A further precursor form of 200 Kd appeared within 2 H. All labelled precursor forms were no longer evident by 4 H. Apparent labelled brush border forms of lactase of 220, 130, and 95 Kd were evident by 2 H and were still present after 18 H. Using similar methodology, we have examined precursors of sucrase-isomaltase, with confirmation of existence of mature and immature precursor forms of 250 and 240 Kd respectively. Demonstration of lactase precursor forms determined in vivo provides confirmation of similar in vitro findings. These studies are consistent with the initial intra-cellular synthesis of high molecular weight precursor forms of lactase with subsequent transfer to brush border sites.