Christian V. Hulzebos

Cyclosporine A-induced reduction of bile salt synthesis associated with increased plasma lipids in children after liver transplantation.

Hyperlipidemia is a common side effect of cyclosporine A (CsA) after solid organ transplantation. CsA also markedly reduces the synthesis rate of bile salts in rats and can inhibit biliary bile salt secretion. It is not known, however, whether CsA inhibits the synthesis of bile salts in humans, and whether the hyperlipidemic effects of CsA are related to bile salt metabolism. Our objective was to assess the effects of CsA on the synthesis rate of bile salts and on plasma triglycerides and cholesterol levels in pediatric liver transplant patients. Before and after discontinuation of CsA treatment after liver transplantation, synthesis rate and pool size of the primary bile salts cholate and chenodeoxycholate were determined using a stable isotope dilution technique and related to plasma lipids. In 6 children (age: 3–16 years) CsA treatment was discontinued at 2 years (median 2.3 years) after liver transplantation. Discontinuation of CsA increased synthesis rate of chenodeoxycholate (+38%, P < .001) and cholate (+21%, P < .05) and the pool size of chenodeoxycholate (+54%, P < .001). Discontinuation of CsA decreased plasma levels of cholesterol (–18%, P < .05) and triglycerides (–23%, P < .05). Bile salt synthesis rate appeared to be inversely correlated with plasma cholesterol (Spearman rank correlation coefficient [rs] = −0.82, P < .01) and plasma triglyceride levels (rs = −0.62, P < .05). In conclusion, CsA inhibits bile salt synthesis and increases plasma concentration of cholesterol and triglycerides in pediatric liver transplant patients. Suppression of bile salt synthesis by long‐term CsA treatment may contribute to hyperlipidemia and thus to increased risk for cardiovascular disease. (Liver Transpl 2004;10:872–880.)

Intestinal Fatty Acid-Binding Protein as a Diagnostic Marker for Complicated and Uncomplicated Necrotizing Enterocolitis: A Prospective Cohort Study

Background Early NEC symptoms are non-specific and diagnostic tests lack discriminative power. Intestinal fatty acid-binding protein (I-FABP), mainly located in small bowel enterocytes, is released into the blood following NEC-associated enterocyte disruption. Aim of this prospective cohort trial was to determine the diagnostic value of I-FABP measured in plasma (I-FABPp) and urine (I-FABPu) for the presence of NEC, to evaluate I-FABP levels during NEC development, and to assess its prognostic value for the progression from suspected to complicated disease. Methods Between 2010 and 2012 we prospectively enrolled neonates with suspected NEC. We measured I-FABP levels eight-hourly from onset of suspected NEC for at least 48 hours, or until surgery. NEC diagnosis was confirmed radiologically or during operation. We defined NEC as complicated if it resulted in surgery and/or death. We determined disease course and diagnostic I-FABP cut-off points. Results The study comprised 37 neonates (24M, 13F), gestational age 28 (24–36) weeks, birth weight 1190 (570–2,400) grams. We found significantly higher I-FABPp and I-FABPu levels in NEC patients (n = 22) than in patients with other diagnoses (n = 15). Cut-off values for diagnosing NEC were 9 ng/mL I-FABPp and 218 ng/mL I-FABPu, with corresponding likelihood ratios (LRs) of 5.6 (95% CI 0.89–35) and 5.1 (95% CI 0.73–36), respectively. I-FABP levels were highest in the first eight hours after symptom onset and gradually decreased over time. Cut-off values for complicated disease were 19 ng/mL I-FABPp and 232 ng/mL I-FABPu, with LRs of 10 (95% CI 1.6–70) and 11 (95% CI 1.6–81), respectively. Conclusions Both plasma and urinary I-FABP levels specifically identify NEC in preterm infants prior to appearance of diagnostic radiological signs suggestive for NEC. Moreover, serial I-FABP measurements accurately predict development of complicated disease.

Usefulness of the bilirubin/albumin ratio for predicting bilirubin-induced neurotoxicity in premature infants

Unconjugated hyperbilirubinaemia occurs in almost all premature infants and is potentially neurotoxic. Treatment is based on total serum bilirubin (TSB), but treatment thresholds are not evidence based. Free bilirubin (Bf)—that is, not bound to albumin, seems a better parameter for bilirubin neurotoxicity, but measurements of Bf are not available in clinical practice. The bilirubin/albumin (B/A) ratio is considered a surrogate parameter for Bf and an interesting additional parameter in the management of hyperbilirubinaemia. This paper reviewed the evidence supporting the use of B/A ratios for predicting bilirubin-induced neurological dysfunction (BIND) including neurodevelopmental delay in jaundiced premature infants (gestational age less than 32 weeks). A literature search was performed and six publications reviewed regarding B/A ratios in the management and outcome of jaundiced premature infants. No prospective clinical trials had been undertaken to show whether bilirubin-induced neurotoxicity is reduced or whether unnecessary treatment is avoided by using the B/A ratio in addition to TSB. Recently, a randomised controlled trial evaluating the effect of the additional use of the B/A ratio on neurodevelopmental outcome in jaundiced premature infants has been initiated. Based on the prevailing evidence many authorities suggest that the additional use of the B/A ratio may be valuable when evaluating jaundiced premature infants.

Cerebral oxygenation is associated with neurodevelopmental outcome of preterm children at age 2 to 3 years

The aim of the study was to determine whether regional cerebral tissue oxygen saturation (rcSO2) and fractional tissue oxygen extraction (FTOE), using near‐infrared spectroscopy, are associated with neurodevelopmental outcome of preterm infants.

Neonatal side effects of maternal labetalol treatment in severe preeclampsia

OBJECTIVE Labetalol is often used in severe preeclampsia (PE). Hypotension, bradycardia and hypoglycemia are feared neonatal side effects, but may also occur in (preterm) infants regardless of labetalol exposure. We analyzed the possible association between intrauterine labetalol exposure and such side effects. STUDY DESIGN From 1 January 2003 through 31 March 2008, all infants from mothers suffering severe PE admitted to one tertiary care center were included. Severe PE was defined according to the International Society for the Study of Hypertension in Pregnancy (ISSHP) criteria. Infants exposed to labetalol in utero (labetalol infants) were compared with infants, who were not exposed to labetalol (controls). Neonatal records were reviewed for hypotension (RR<mean gestational age in weeks), bradycardia (heartrate<100/min) and hypoglycaemia (glucose<2.7 mmol/L) in the first 48 postnatal hours. RESULTS Of 109 infants, 55 had been exposed to labetalol, whereas 54 were not (controls). Gestational age at delivery and birthweight were similar in both groups (31.8 vs. 32.8 weeks (p=0.06) and 1510 vs. 1639 grams (p=0.25), respectively for the labetalol vs. control group). Hypotension occurred significantly more in conjunction with labetalol exposure (16, (29.1%) vs. 4 (7.4%); p=0.003), irrespective of the route of administration. Patent ductus arteriosus (PDA) was present in 9 (56%) of hypotensive labetalol infants compared to 1 (24%) infant in the hypotensive control group (NS). In a multivariate regression model, labetalol exposure, the need for intubation and PDA appeared independently associated with hypotension (P<0.001). Hypoglycemia occurred in 26 (47.3%) of labetalol infants and in 23 (42.6%) of control infants (p=0.62). Bradycardia occurred in 4 (7.3%) of labetalol infants and in 1 (1.9%) of control infants (p=0.18). Hypoglycemia was more common in premature infants (n=45 (48,9%) vs. n=4 (23.5%), p=0.05) in both labetalol and control infants. CONCLUSION Hypotension is more common after maternal labetalol exposure, regardless of the dosage and route of administration. The need for intubation and the presence of a PDA also play a role. Hypoglycemia is a very common finding in this population and is merely related to prematurity and independent of labetalol exposure as was the incidental occurrence of bradycardia. These findings on the neonatal side effects of maternal labetalol treatment in preeclampsia underline the importance of frequent blood glucose and blood pressure measurements in the first days of life, especially in intubated preterm infants with a PDA.

Thrombocytopaenia and intraventricular haemorrhage in very premature infants: a tale of two cities

Objective To study whether the incidence of intraventricular haemorrhage (IVH) in very premature infants (<32 weeks gestation) with thrombocytopaenia is lower when using a liberal platelet-transfusion guideline compared with a restrictive guideline. Study design A retrospective cohort study comparing the incidence of IVH in very premature infants with thrombocytopaenia (platelet count <150×109/l) admitted between 2007 and 2008 to two neonatal intensive care unit in The Netherlands. The restrictive platelet-transfusion unit (N=353 infants <32 weeks gestation) transfused only in case of active haemorrhage and a platelet count <50×109/l. The liberal-transfusion unit (N=326 infants <32 weeks gestation) transfused according to predefined platelet count thresholds. Primary outcome was the incidence and severity of IVH in infants with thrombocytopaenia in both units. Results The number of infants with thrombocytopaenia that received a platelet transfusion was significantly lower in the restrictive-transfusion unit compared with the liberal-transfusion unit, 15% (21/145) versus 31% (41/141), (p<0.001). The incidence of IVH in infants with thrombocytopaenia in the restrictive-transfusion and liberal-transfusion units was 30% (44/145) and 29% (41/141), respectively (p=0.81). The incidence of severe IVH (grade 3 or 4) in the restrictive-transfusion and liberal-transfusion units was 8% (12/145) and 11% (16/141), respectively (p=0.38). Conclusion In the restrictive-transfusion unit, the rate of platelet transfusions was significantly lower, but the incidence and severity of IVH was similar to the liberal-transfusion unit.

Severe Neonatal Hyperbilirubinemia in the Netherlands

Background: The occurrence of severe neonatal hyperbilirubinemia (SH) is partly attributed to nonhospitalized perinatal care. The Netherlands have a high frequency of home births and nonhospitalized perinatal care, and the incidence of SH is unknown. Objective: To assess the effects of home births and early hospital discharge on the incidence of SH in term-born infants in the Netherlands. Methods: In this nationwide prospective surveillance study between 2005 and 2009, infants (≥37 weeks GA) were included if total serum bilirubin (TSB) was ≥500 µmol/l or if they received an exchange transfusion when TSB was ≥340 µmol/l. Results: Seventy-one infants had SH (incidence 10.4/100,000); 43 had a TSB ≥500 μmol/l (incidence 6.3/100,000) and 45 (63%) underwent an exchange transfusion. 26% of the infants with SH were born at home, which is similar to 22% of all term infants who are born at home in the Netherlands (p = 0.41). Maximum TSB levels were similar in infants born at home (523 ± 114 μmol/l) and infants born in hospital (510 ± 123 μmol/l; p = 0.70). Of the 51 infants born in hospital, 33 were discharged and readmitted with SH, with maximal TSB levels (567 ± 114 μmol/l), which were higher than in infants who remained hospitalized (406 ± 47 μmol/l; p = 0.0001). Conclusion: The incidence of severe hyperbilirubinemia in term-born infants in the Netherlands is 10.4 per 100,000, which is similar to other developed countries. Home birth and early hospital discharge do not necessarily lead to a higher incidence of SH, provided that perinatal home care is well organized.

Beyond plasma bilirubin: The effects of phototherapy and albumin on brain bilirubin levels in Gunn rats

BACKGROUND & AIMS Severe unconjugated hyperbilirubinemia, as occurs in Crigler-Najjar disease and neonatal jaundice, carries the risk of neurotoxicity. This neurotoxicity is related to the increased passage of free bilirubin (UCB(free)), the fraction of bilirubin that is not bound to plasma proteins, into the brain. We hypothesized that albumin treatment would lower the UCB(free) fraction, and thus decrease bilirubin accumulation in the brain. METHODS We treated chronic (e.g., as a model for Crigler-Najjar disease) and acute hemolytic (e.g., as a model for neonatal jaundice) moderate hyperbilirubinemic Gunn rats with phototherapy, human serum albumin (HSA) or phototherapy+HSA. RESULTS In the chronic model, adjunct HSA increased the efficacy of phototherapy; it decreased plasma UCB(free) and brain bilirubin by 88% and 67%, respectively (p<0.001). In the acute model, adjunct HSA also increased the efficacy of phototherapy; it decreased plasma UCB(free) by 76% (p<0.001) and completely prevented the hemolysis-induced deposition of bilirubin in the brain. Phototherapy alone failed to prevent the deposition of bilirubin in the brain during acute hemolytic jaundice. CONCLUSIONS We showed that adjunct HSA treatment decreases brain bilirubin levels in phototherapy-treated Gunn rats. We hypothesize that HSA decreases these levels by lowering UCB(free) in the plasma. Our results support the feasibility of adjunct albumin treatment in patients with Crigler-Najjar disease or neonatal jaundice.

Cholesterol Synthesis and De Novo Lipogenesis in Premature Infants Determined by Mass Isotopomer Distribution Analysis

Premature infants change from placental supply of mainly carbohydrates to an enteral supply of mainly lipids earlier in their development than term infants. The metabolic consequences hereof are not known but might have long-lasting health effects. In fact, knowledge of lipid metabolism in premature infants is very limited. We have quantified de novo lipogenesis and cholesterogenesis on d 3 of life in seven premature infants (birth weight, 1319 ± 417 g; gestational age, 30 ± 2 wk). For comparison, five healthy adult subjects were also studied. All subjects received a 12-h [1-13C] acetate infusion, followed by mass isotopomer distribution analysis (MIDA) on lipoprotein-palmitate and plasma unesterified cholesterol. The fraction of lipoprotein-palmitate synthesized at the end of the infusion period was 5.4 ± 3.9% in infants, which was in the same range as found in adult subjects on a normal diet, suggesting that hepatic de novo lipogenesis is not a major contributor to fat accumulation in these premature neonates. The fractional contribution of newly synthesized cholesterol to plasma unesterified cholesterol was 7.4 ± 1.3% after a 12-h infusion. The calculated rate of endogenous cholesterol synthesis was 31 ± 7 mg/kg/d, a value approximately three times higher than that found in adult subjects (10 ± 6 mg/kg/d). These results indicate that the cholesterol-synthesizing machinery is well developed in premature infants.

Bilirubin-albumin binding, bilirubin/albumin ratios, and free bilirubin levels: where do we stand?

Treatment for unconjugated hyperbilirubinemia is predominantly based on one parameter, i.e., total serum bilirubin (TSB) levels. Yet, overt kernicterus has been reported in preterm infants at relatively low TSB levels, and it has been repeatedly shown that free unconjugated bilirubin (freeUCB) levels, or bilirubin/albumin (B/A) ratios for that matter, are more closely associated with bilirubin neurotoxicity. In this article, we review bilirubin-albumin binding, UCBfree levels, and B/A ratios in addition to TSB levels to individualize and optimize treatment especially in preterm infants. Methods to measure bilirubin-albumin binding or UCBfree are neither routinely performed in Western clinical laboratories nor incorporated in current management guidelines on unconjugated hyperbilirubinemia. For bilirubin-albumin binding, this seems justified because several of these methods have been challenged, and sufficiently powered prospective trials on the clinical benefits are lacking. Technological advances in the measurement of UCBfree may provide a convenient means for integrating UCBfree measurements into routine clinical management of jaundiced infants. A point-of-care method, as well as determination of UCBfree levels in various newborn populations, is desirable to learn more about variations in time and how various clinical pathophysiological conditions affect UCBfree levels. This will improve the estimation of approximate UCBfree levels associated with neurotoxicity. To delineate the role of UCBfree in the management of jaundiced (preterm) infants, trials are needed using UCBfree as treatment parameter. The additional use of the B/A ratio in jaundiced preterms has been evaluated in the Bilirubin Albumin Ratio Trial (BARTrial; Clinical Trials: ISRCTN74465643) but failed to demonstrate better neurodevelopmental outcome in preterm infants <32 weeks assigned to the study group. Awaiting a study in which infants are assigned to be managed solely on the basis of their B/A ratio (with TSB excluded ) versus TSB levels alone-and determining which group does better-the additional use of the B/A ratio in the management of hyperbilirubinemia in preterms is not advised. In conjunction with TSB levels, other parameters possibly allow for more accurate prediction of bilirubin toxicity. Yet, different methodologies for estimating these parameters exist, and sufficiently powered, prospective clinical trials supporting their clinical benefit, i.e., reduced bilirubin neurotoxicity when using these parameters, are lacking. Their use in addition to TSB needs to be prospectively evaluated, especially in preterm neonates, and preferentially in randomized clinical trials, which include specific risk factors and assessment of clinical relevant outcome measures for detecting those infants at risk of bilirubin toxicity.