Diffusion tensor imaging detects areas of abnormal white matter microstructure in patients with partial ornithine transcarbamylase deficiency.

BACKGROUND AND PURPOSE: OTCD, an X-linked disorder, is the most common of the UCDs. Neonatal onset is associated with uniformly poor outcome. Males with late-onset OTCD show deficits in executive function, motor planning, and working memory. A broad phenotype is observed in heterozygous females. A specific neurobehavioral phenotype with white matter dysfunction and impaired attention and working memory has been described. The extent to which the deficits involve specific pathways in the brain is unknown. We hypothesized that DTI would disclose white matter microstructure in OTCD correlating with cognitive deficits. MATERIALS AND METHODS: Nineteen adults with partial OTCD and 18 adult control subjects ages 19-59 years participated. MR imaging was performed by using a 3T whole-body scanner. Anisotropy was calculated from the eigenvalues of the diffusion tensor by using the FA metric and was compared between the study and control groups. RESULTS: FA of the frontal white matter was significantly decreased in subjects, indicating changes in white matter microstructure. There was an inverse relationship between FA and disease severity, but not with age. CONCLUSIONS: Findings of MR imaging in OTCD are often normal in patients with late-onset disease, heterozygotes, or in those not in hyperammonemic crisis. DTI was more sensitive than FSE T2-weighted imaging for detecting abnormalities in normal-appearing white matter. The extent of abnormality correlated with cognitive deficits. The location of the deficits in the frontal white matter is important because this area connects fibers that are vital to executive function, attention, and working memory.

Evaluation of a long-chain polyunsaturated fatty acid supplemented formula on growth, tolerance, and plasma lipids in preterm infants up to 48 weeks postconceptional age.

BACKGROUND: The last trimester of pregnancy is a period of rapid accretion of long-chain polyunsaturated fatty acids, both in the central nervous system and the body as a whole. Human milk contains these fatty acids, whereas some preterm infant formulas do not. Infants fed formulas without these fatty acids have lower plasma and erythrocyte concentrations than infants fed human milk. Preclinical and clinical studies have demonstrated that single-cell sources (algal and fungal) of long-chain polyunsaturated fatty acids are bioavailable. A balanced addition of fatty acids from these oils to preterm formula results in blood fatty acid concentrations in low birth weight infants comparable to those of infants fed human milk. METHODS: In the present study the growth, acceptance (overall incidence of discontinuation, reasons for discontinuation, overall incidence and type of individual adverse events), and plasma fatty acid concentrations were compared in three groups of infants fed a long-chain polyunsaturated fatty acid-supplemented preterm infant formula, an unsupplemented control formula, or human milk. The study was prospective, double-blind (formula groups only), and randomized (formula groups only). Two hundred eighty-eight infants were enrolled (supplemented formula group, n = 77; control formula group, n = 78; human milk group, n = 133). RESULTS: Anthropometric measurements at enrollment, at first day of full oral feeding, and at both 40 and 48 weeks postconceptional age did not differ between the formula groups, whereas the human milk-fed group initially grew at a lower rate. The incidence of severe adverse events was rare and not significantly different between formula groups. The groups fed either human milk or supplemented formula had long-chain polyunsaturated fatty acid concentrations higher than those in the control formula group. CONCLUSIONS: The results of this study demonstrate the safety and efficacy of a preterm formula supplemented with long-chain polyunsaturated fatty acids from single-cell oils.

Bone turnover in preterm infants.

Total parenteral nutrition is associated with osteopenia in preterm infants. Insufficient calcium and phosphate are likely causes: aluminum contamination is another possible contributing factor as this adversely affects bone formation and mineralization. The study was designed to evaluate changes in biochemical markers of bone turnover in 22 preterm infants receiving total parenteral nutrition in comparison with 19 term infants. We collected urine and serum samples from 22 preterm infants, mean gestational age 29 wk, within 48 h and again at 3 wk of life. We also collected urine samples from 19 term infants, mean gestational age 39 wk, during the first day of life. Bone resorption was assessed by the measurement of urinary pyridinium cross-links by HPLC and ELISA and the N-telopeptide of type I collagen by ELISA. Bone formation was assessed in premature infants by the measurement of serum osteocalcin. The N-telopeptide of type I collagen was higher in the preterm infants compared with term at baseline (p < 0.01). There was no difference between the pyridinium cross-links in the preterm and term infants. All the biochemical markers of bone turnover increased significantly in the preterm infants during the first 3 wk of life, e.g. N-telopeptide was a 153% change from baseline (p < 0.001). Aluminum in the total parenteral nutrition solutions did not cause a decrease in bone formation at the level administered (3-6 microg, 0.1-0.2 micromol x kg(-1) x d(-1)).

Massive intracranial immature teratoma with extracranial extension into oral cavity, nose, and neck.

We present a case of congenital massive intracranial teratoma with extracranial extension into oral cavity, nose, and neck diagnosed by antenatal ultrasonography at 25 weeks of gestation. The fetus was delivered by cesarean section because of massive fetal head size and severe maternal pregnancy-induced hypertension. At necropsy the tumor was found to be an immature teratoma, with no recognizable normal brain tissue. An additional finding was hepatomegaly secondary to extensive extramedullary hematopoiesis. Karyotyping of both the fetus and the teratoma revealed a normal female chromosomal composition: 46,XX.

N-acetylcysteine protects from glutathione depletion in rats exposed to hyperoxia.

BACKGROUND: N-acetylcysteine (NAC) may protect against oxidative injury by providing cysteine for glutathione (GSH) biosynthesis or by direct reactions with electrophiles. We have recently shown that hyperoxic exposure of rats prior to liver perfusion is associated with significant decreases in hepatic GSH and significant changes in biliary amino acid concentrations. We hypothesized that NAC administration during hyperoxic exposure would prevent depletion of hepatic GSH by providing cysteine for GSH biosynthesis. METHODS: NAC was administered during two conditions known to induce GSH depletion: hyperoxic exposure and biochemical inhibition of GSH synthesis using buthionine sulfoximine (BSO). After 48 hours, GSH concentrations in bile, liver and perfusate and biliary amino acid concentrations were determined using isolated perfused liver preparations. RESULTS: Administration of NAC to rats maintained in normoxic or hyperoxic conditions, prior to liver perfusion, resulted in dose-dependent increases in GSH concentrations in bile, liver and perfusate, increases in bile flow rates and changes in biliary amino acid concentrations. When BSO was given concurrently with NAC in normal or hyperoxic conditions, these effects were not observed, and oxidant stress was evident. CONCLUSIONS: NAC prevents oxidant stress during hyperoxic exposure, most likely by supplying cysteine as a precursor for GSH synthesis.

Impact of transfusion guidelines on neonatal transfusions.

BACKGROUND: Preterm infants with birth weights (BW) <1250 gm are given multiple blood transfusions either for replacement of blood loss or for correction of symptomatic anemia of prematurity. OBJECTIVE: To assess the effectiveness of transfusion guidelines in reducing the number of transfusions given to infants with BW <1250 gm. METHODS: This cohort study was conducted at the regional teaching medical center with level III obstetric and neonatal services. Preterm infants with BW <1250 gm and gestational age <32 weeks were admitted to the neonatal intensive care unit during a period of 6 months before and after implementation of transfusion guidelines. The final sample size constituted 39 infants before guidelines (BG) and 41 infants after guidelines (AG). The primary outcome measure was the total number and volume of transfusions given per infant in the first 2 weeks of life and before discharge from the nursery. RESULTS: We observed a significant reduction in the mean number (4.7 to 2.7, p = 0.003) and volume (52 ml to 30 ml, p = 0.0005) of transfusions given per infant in the first 2 weeks of life, as well as a definite trend toward reduction in the total number (10.5 to 8.0, p = 0.08) and volume (156 ml to 119 ml, p = 0.07) of transfusions given before discharge in the BG versus AG, respectively. When all the transfusions given to the 41 infants in the AG group were analyzed for compliance with guidelines, 96% (313 of 328) were observed to be in compliance. CONCLUSION: This study shows that transfusion guidelines are effective in decreasing the number of transfusion given to infants with BW <1250 gm. An indirect benefit of guidelines contributing to a reduced number of transfusions may be a heightened awareness to decrease blood losses.

Hyperoxia and glutathione depletion in the isolated perfused rat liver.

BACKGROUND: Hepatic stores of glutathione may be depleted by hyperoxic exposure or poor nutritional status. We studied the effects of hyperoxia or hepatic glutathione depletion on bile flow rates, and on biliary concentrations of glutathione and amino acids. METHODS: Glutathione depletion was induced in vivo by 1) hyperoxic exposure (O2) for 48 hours, 2) inhibition of glutathione synthesis by treatment with buthionine sulfoximine (BSO), 3) a combination of BSO + O2, or 4) inhibition of cysteine synthesis by propargyglycine (PPG). Livers were then isolated and perfused. RESULTS: Glutathione concentrations in bile, liver, and perfusate were significantly decreased by all treatments. Bile flow was significantly decreased in groups treated with BSO or O2 + BSO, and perfusate LDH was increased by O2 + BSO or PPG. Significant changes in biliary amino acid concentrations included decreased sulfur-containing amino acids and increased branched-chain amino acids in groups treated with BSO, PPG, or O2; and increased essential amino acids in groups treated with O2 or PPG. CONCLUSION: Oxygen exposure or inhibition of glutathione synthesis results in significant decreases in hepatic, perfusate and biliary glutathione concentrations, and increases in biliary amino acids. A decrease in bile flow rate was associated only with the most severe glutathione depletion.

Colonization and infection associated with Malassezia and Candida species in a neonatal unit.

The objectives of this study were to determine, in neonates of < 1250 g birthweight (N = 57), the initial time of skin colonization by Malassezia furfur, rate of colonization by Candida spp., and whether skin colonization by these yeasts was predictive of central line colonization or fungaemia. By age two weeks, 51% of neonates were culture-positive for M. furfur on umbilical or groin skin. During hospitalization, positive skin cultures for M. furfur or Candida spp. were obtained in 70% and 37% of neonates, respectively. Risk factors associated with positive skin cultures were mechanical ventilation and three or more episodes of suspected sepsis. Eight of the 52 infants with central venous catheters, had positive blood cultures withdrawn from the lines; five (62%) of these had positive skin surveillance cultures. Although positive skin cultures for M. furfur, Candida spp., or both were commonly observed in this population, they were not predictive of positive central line cultures or systemic illness.

The acute effects of TNF-alpha on the isolated perfused rat liver.

BACKGROUND: TNF-alpha mediates the hepatic response to sepsis by mechanisms which are not well understood. TNF-alpha is known to stimulate the hepatocellular uptake of specific amino acids in vivo; however, little is known about the direct effects of TNF-alpha on hepatic amino acid or glutathione homeostasis, which is a potential factor in the acute hepatic response to sepsis. METHODS: Using the isolated perfused rat liver, we characterized the effects of TNF-alpha on the secretion of amino acids and glutathione into bile and perfusate. Livers taken from adult male Sprague-Dawley rats were perfused with TNF-alpha at a dose of 1 or 2 micrograms. Bile and perfusate were collected for the quantitation of amino acid and glutathione concentrations. RESULTS: Administration of 2 micrograms TNF-alpha resulted in significant increases in biliary and perfusate concentrations of branched chain, gluconeogenic, and total amino acids. TNF-alpha was also associated with dose-related increases in oxygen uptake, and greater biliary concentrations of glutathione. CONCLUSION: TNF-alpha has direct effects upon hepatic amino acid metabolism, which represent some of the early events involved in the mechanism of response to sepsis.

Nasogastric intubation for nutrition and airway protection in infants with Robin sequence.

Airway obstruction and feeding difficulty associated with Robin sequence may be difficult management problems that require invasive therapeutic measures. We present two cases of infants with airway obstruction who were treated successfully as outpatients by placement of a nasogastric tube for airway maintenance and supplementation of oral feeding. In patients with Robin sequence who have upper airway obstruction and feeding difficulties not resolved by prone positioning, placement of an indwelling nasogastric tube should be considered before an invasive surgical procedure is undertaken.

The effects of light exposure on the in vitro hepatic response to an amino acid-vitamin solution.

BACKGROUND: Administration of parenteral nutrition (PN) that has been irradiated with light is associated with hepatic dysfunction in rats in vivo. Using the isolated perfused rat liver, we report the in vitro hepatic response to a light-exposed amino acid-vitamin (AAV) solution, compared with a light-protected solution. METHODS: The amino acid-vitamin solution (3 g Aminosyn and 2.5 mL MVI-12 added to buffer) was placed under a lamp in a beaker that was covered completely with foil (light-protected) or with a transparent wrap (light-exposed) for 24 hours before liver perfusion. Livers from adult male rats were isolated and perfused with buffer for 30 minutes, with the AAV solution for 60 minutes, and again with buffer for 30 minutes. RESULTS: Infusion with the AAV solution resulted in decreases in bile flow rates. Compared with light-protected groups, light-exposure was associated with significantly lower bile flow rates, significant increases in biliary concentrations of oxidized glutathione (GSSG), and significantly decreased biliary concentrations of free amino acids, including the glutathione precursors glutamate and glycine. CONCLUSIONS: Perfusion of the isolated rat liver with an AAV solution that has been irradiated with light for 24 hours results in a decrease in bile flow rates and an increase in biliary GSSG concentrations, suggesting oxidant stress. Consideration should be given to protecting solutions from light in the clinical setting.

Biliary amino acid and glutathione secretion in response to amino acid infusion in the isolated rat liver.

The intravenous infusion of amino acid solutions has been associated with cholestatic liver injury in hospitalized patients and in laboratory animals. In the isolated rat liver, we recently showed that the acute decrease in bile flow, previously reported by other investigators, is dose related, reversible, and associated with dose-related increases in total biliary amino acid concentrations. In the present study, we characterized the effects of graded infusions of amino acid solutions, with and without taurocholate, on biliary secretion of individual amino acids and glutathione, an important regulator of bile flow. Livers from young adult male rats were perfused with an amino acid solution for 1 hour and allowed to recover for 30 minutes. Infusion of the amino acid solution was associated with dose-related increases in biliary concentrations of most amino acids included in the amino acid solution. Infusion of amino acid solutions resulted in a decreased bile/perfusate ratio of most amino acids, which were secreted into bile in amounts approximating their calculated uptake from the infusate. The inclusion of taurocholate in the infusate was associated with lower biliary concentrations of each individual amino acid and significant decreases in biliary total, reduced, and oxidized glutathione. Further investigation of the relationship between these changes in biliary amino acids and glutathione concentrations and the cholestasis associated with infusion of amino acid solutions may provide insights into the mechanism by which amino acids induce such cholestasis.

Amino acid infusions induce reversible, dose-related decreases in bile flow in the isolated rat liver.

Parenteral infusion of amino acid solutions is known to produce cholestasis in experimental animal models and in the isolated perfused rat liver. To characterize the dose responsiveness and reversibility of amino acid-induced cholestasis, isolated rat livers were perfused with solutions containing 1.5, 3.0, or 6.0 g of amino acids for 1 hour and allowed to recover for 30 minutes. Perfusion of livers resulted in a rapid, dose-related decrease in bile flow (p < .0001 at doses of 3.0 and 6.0 g). When the amino acid solution was discontinued, bile flow recovered to near control rates. Infusion of taurocholate reduced the magnitude of the decrease in bile flow associated with amino acid infusion but did not prevent it. Infusion of amino acid solutions was associated with the following changes in bile: (1) dose-related increases in total free amino acid concentrations; (2) increased osmolarity; (3) increased glucose concentrations; (4) increased potassium concentrations; (5) decreased chloride concentrations; (6) increased oxygen uptake in livers not perfused with added taurocholate; and (7) increased total bile acid concentrations in livers perfused with added taurocholate. Additional investigations are needed to determine whether these associations are attributable to individual amino acids or the total metabolic load of the amino acids.

The changing spectrum of neonatal meningitis over a fifteen-year period.

One hundred seventy-seven cases of neonatal meningitis treated at the University of Texas Medical Branch at Galveston over a 15-year period (1974-1988) were reviewed. Over this period, the incidence of bacterial meningitis decreased, the incidence of aseptic meningitis remained stable, and the diagnosis of enteroviral meningitis increased in frequency. During 1984-1988, enterovirus was the most common cause of meningitis in neonates older than seven days and accounted for one third of all cases of neonatal meningitis. Half of all neonates with bacterial meningitis had negative blood cultures. We recommend that 1) diagnostic lumbar puncture remain part of the routine assessment of the neonate with suspected sepsis, and 2) CSF be cultured for enterovirus as well as for bacteria when a neonate older than seven days presents with suspected sepsis.

Hepatic metabolism of short-chain bile acids. Inversion of the 3-hydroxyl group of isoetianic acid (3 beta-hydroxy-5 beta-androstane-17 beta-carboxylic acid) by the adult rat.

The stereospecificity of mechanisms for hepatic transport of short-chain bile acids has been examined by following the hepatic metabolism and biliary secretion of 3 beta-hydroxy-5 beta-androstane-17 beta-carboxylic acid (isoetianic acid) administered in two different labeled forms to rats prepared with an external biliary fistula. While 93% of the administered [2,2,4,4-3H]isoetianic acid was recovered in bile after 20 h, only 18% of a similar dose of [3 alpha-3H]isoetianic acid was secreted in bile over the same time period. The recovered radioactivity of the latter compound was mainly associated with bile water. With the [2,2,4,4-3H]isoetianic acid, the bulk of the biliary isotope was determined to be in the form of two glucuronide conjugates. Spectral analysis identified these metabolites as the hydroxyl-linked (major) and carboxyl-linked (minor) beta-glucuronides, not of the 3 beta-hydroxy compound administered, but of 3 alpha-hydroxy-5 beta-androstane-17 beta-carboxylic acid (etianic acid), i.e., the products of hydroxyl group inversion. It is concluded that isoetianic acid is efficiently cleared from plasma and conjugated with glucuronic acid after its epimerization to etianic acid. The prevalent, but not complete, loss of the 3-tritium atom and the retention of the 2- and 4-tritium atoms probably indicates a 3-oxo-5 beta-androstane-17 beta-carboxylic acid intermediate with partial return of the label via a limited labeled pool of reduced nicotinamide cofactor.

Multiple congenital anomalies associated with a 47,XXX chromosome constitution.

An infant with a 47,XXX chromosome constitution, who died shortly after birth, had laryngeal atresia, pulmonary hypoplasia, craniofacial anomalies, urogenital malformations including unilateral renal agenesis, hydrometrocolpos and ovarian dysgenesis, and mildly abnormal endochondral ossification. Implications for genetic counseling are presented.

Metabolism of lithocholic acid in the rat: formation of lithocholic acid 3-O-glucuronide in vivo.

Milligram amounts of [3 beta-3H]lithocholic (3 alpha-hydroxy-5 beta-cholanoic) acid were administered by intravenous infusion to rats prepared with a biliary fistula. Analysis of sequential bile samples by thin-layer chromatography (TLC) demonstrated that lithocholic acid glucuronide was present in bile throughout the course of the experiments and that its secretion rate paralleled that of total isotope secretion. Initial confirmation of the identity of this metabolite was obtained by the recovery of labeled lithocholic acid after beta-glucuronidase hydrolysis of bile samples. For detailed analysis of biliary metabolites of [3H]lithocholic acid, pooled bile samples from infused rats were subjected to reversed-phase chromatography and four major labeled peaks were isolated. After complete deconjugation, the two major compounds in the combined first two peaks were identified as murideoxycholic (3 alpha, 6 beta-dihydroxy-5 beta-cholanoic) and beta-muricholic (3 alpha, 6 beta, 7 beta-trihydroxy-5 beta-cholanoic) acids and the third peak was identified as taurolithocholic acid. The major component of the fourth peak, after isolation, derivatization (to the methyl ester acetate), and purification by high pressure liquid chromatography (HPLC), was positively identified by proton nuclear magnetic resonance as lithocholic acid 3 alpha-O-(beta-D-glucuronide). These studies have shown, for the first time, that lithocholic acid glucuronide is a product of in vivo hepatic metabolism of lithocholic acid in the rat.

Evaluation of hexosaminidase activity as a potential biochemical marker in serum for necrotizing enterocolitis.

The presence of increased serum activity of the lysosomal hydrolase hexosaminidase has been suggested to be potentially useful in the diagnosis of neonatal necrotizing enterocolitis (NEC). In the present study, serum activity of hexosaminidase was measured in 19 neonates with NEC and compared to developmental patterns of enzyme activity determined in 61 neonates without NEC. Infants with NEC were studied at intervals starting at the onset of disease and continuing until 6 weeks after diagnosis. In normal infants, serum activity of hexosaminidase increases with increasing gestational and postnatal ages. However, infants with NEC had relatively lower serum hexosaminidase activity than these control infants of similar gestational and postnatal ages. Necrotizing enterocolitis is not associated with increased serum activity of hexosaminidase.

Metabolism of 24-norlithocholic acid in the rat: formation of hydroxyl- and carboxyl-linked glucuronides and effect on bile flow.

24-Norlithocholic (3 alpha-hydroxy-24-nor-5 beta-cholan-23-oic) acid is the lower homologue of lithocholic acid, a potent cholestatic agent. In order to characterize its cholestatic potential and metabolic fate, 3 beta-tritiated 24-norlithocholate was infused intravenously into adult male Sprague-Dawley rats prepared with an external biliary fistula. The results demonstrate that 24-norlithocholate does not induce cholestasis in rats when administered in doses in excess of those necessary for lithocholate to produce cholestasis. Hydroxyl- and carboxyl-linked glucuronides were identified as major metabolites secreted in the bile. Especially noteworthy is the identification of carboxyl-linked glucuronides of mono-, di- and trihydroxylated C23 bile acids. Their total amount (25% of recovered radioactive products) is comparable to that of the hydroxyl-linked glucuronide of 24-norlithocholic acid (41%). In this study, for the first time, a bile acid diglucuronide, substituted both at 3-hydroxyl and carboxyl groups, was detected (11%).

Development of serum hexosaminidase activity in infants.

Serum activity of hexosaminidases A and B has been measured to identify patients with Tay-Sachs and Sandhoff diseases, and may also be influenced by other clinical conditions including neonatal necrotizing enterocolitis. We have characterized the normal developmental pattern of hexosaminidase activity in serum by measuring this enzyme activity in 61 neonates of 27-40 weeks gestation who were followed from birth to age 4-8 weeks. Total serum hexosaminidase activity significantly increased with postnatal and gestational age, and with initiation of enteral feeding. We conclude that serum hexosaminidase activity in infants with clinical conditions that may influence serum activity of this enzyme must be compared to that in normal infants of similar gestational and postnatal ages.