Intestinal NCoR1, a regulator of epithelial cell maturation, controls neonatal hyperbilirubinemia.

Severe neonatal hyperbilirubinemia (SNH) and the onset of bilirubin encephalopathy and kernicterus result in part from delayed expression of UDP-glucuronosyltransferase 1A1 (UGT1A1) and the inability to metabolize bilirubin. Although there is a good understanding of the early events after birth that lead to the rapid increase in serum bilirubin, the events that control delayed expression of UGT1A1 during development remain a mystery. Humanized UGT1 (hUGT1) mice develop SNH spontaneously, which is linked to repression of both liver and intestinal UGT1A1. In this study, we report that deletion of intestinal nuclear receptor corepressor 1 (NCoR1) completely diminishes hyperbilirubinemia in hUGT1 neonates because of intestinal UGT1A1 gene derepression. Transcriptomic studies and immunohistochemistry analysis demonstrate that NCoR1 plays a major role in repressing developmental maturation of the intestines. Derepression is marked by accelerated metabolic and oxidative phosphorylation, drug metabolism, fatty acid metabolism, and intestinal maturation, events that are controlled predominantly by H3K27 acetylation. The control of NCoR1 function and derepression is linked to IKKß function, as validated in hUGT1 mice with targeted deletion of intestinal IKKß. Physiological events during neonatal development that target activation of an IKKß/NCoR1 loop in intestinal epithelial cells lead to derepression of genes involved in intestinal maturation and bilirubin detoxification. These findings provide a mechanism of NCoR1 in intestinal homeostasis during development and provide a key link to those events that control developmental repression of UGT1A1 and hyperbilirubinemia.

Modulation of bilirubin neurotoxicity by the Abcb1 transporter in the Ugt1-/- lethal mouse model of neonatal hyperbilirubinemia.

Moderate neonatal jaundice is the most common clinical condition during newborn life. However, a combination of factors may result in acute hyperbilirubinemia, placing infants at risk of developing bilirubin encephalopathy and death by kernicterus. While most risk factors are known, the mechanisms acting to reduce susceptibility to bilirubin neurotoxicity remain unclear. The presence of modifier genes modulating the risk of developing bilirubin-induced brain damage is increasingly being recognised. The Abcb1 and Abcc1 members of the ABC family of transporters have been suggested to have an active role in exporting unconjugated bilirubin from the central nervous system into plasma. However, their role in reducing the risk of developing neurological damage and death during neonatal development is still unknown.To this end, we mated Abcb1a/b-/- and Abcc1-/- strains with Ugt1-/- mice, which develop severe neonatal hyperbilirubinemia. While about 60% of Ugt1-/- mice survived after temporary phototherapy, all Abcb1a/b-/-/Ugt1-/- mice died before postnatal day 21, showing higher cerebellar levels of unconjugated bilirubin. Interestingly, Abcc1 role appeared to be less important.In the cerebellum of Ugt1-/- mice, hyperbilirubinemia induced the expression of Car and Pxr nuclear receptors, known regulators of genes involved in the genotoxic response.We demonstrated a critical role of Abcb1 in protecting the cerebellum from bilirubin toxicity during neonatal development, the most clinically relevant phase for human babies, providing further understanding of the mechanisms regulating bilirubin neurotoxicity in vivo. Pharmacological treatments aimed to increase Abcb1 and Abcc1 expression, could represent a therapeutic option to reduce the risk of bilirubin neurotoxicity.

Humanized UGT1 Mice, Regulation of UGT1A1, and the Role of the Intestinal Tract in Neonatal Hyperbilirubinemia and Breast Milk-Induced Jaundice.

Neonatal hyperbilirubinemia and the onset of bilirubin encephalopathy and kernicterus result in part from delayed expression of UDP-glucuronosyltransferase 1A1 (UGT1A1) and the ability to metabolize bilirubin. It is generally believed that acute neonatal forms of hyperbilirubinemia develop due to an inability of hepatic UGT1A1 to metabolize efficiently bilirubin for clearance through the hepatobiliary tract. Newly developed mouse models designed to study bilirubin metabolism have led to new insight into the role of the intestinal tract in controlling neonatal hyperbilirubinemia. Humanization of mice with the UGT1 locus (hUGT1 mice) and the UGT1A1 gene provide a unique tool to study the onset of hyperbilirubinemia since the human UGT1A1 gene is developmentally regulated during the neonatal period in hUGT1 mice. A new mechanism outlying developmental expression of intestinal UGT1A1 is presented and its implications in the control of neonatal hyperbilirubinemia discussed. New findings linking breast milk protection against necrotizing enterocolitis and intestinal control of UGT1A1 may help explain the contribution of breast milk toward the development of neonatal hyperbilirubinemia. Our findings outline a new model that includes an active intestinal ROS /IκB kinase/nuclear receptor corepressor 1 loop that can be applied to an understanding of breast milk-induced jaundice.

Melatonin Promotes Brain-Derived Neurotrophic Factor (BDNF) Expression and Anti-Apoptotic Effects in Neonatal Hemolytic Hyperbilirubinemia via a Phospholipase (PLC)-Mediated Mechanism.

BACKGROUND Melatonin therapy shows positive effects on neuroprotective factor brain-derived neurotrophic factor (BDNF) expression and neuronal apoptosis in neonatal hemolytic hyperbilirubinemia. We hypothesized that melatonin promotes BDNF expression and anti-apoptotic effects in neonatal hemolytic hyperbilirubinemia through a phospholipase (PLC)-mediated mechanism. MATERIAL AND METHODS A phenylhydrazine hydrochloride (PHZ)-induced neonatal hemolytic hyperbilirubinemia model was constructed in neonatal rats. Four experimental groups - a control group (n=30), a PHZ group (n=30), a PHZ + melatonin group (n=30), and a PHZ + melatonin+U73122 (a PLC inhibitor) group (n=30) - were constructed. Trunk blood was assayed for serum hemoglobin, hematocrit, total and direct bilirubin, BDNF, S100B, and tau protein levels. Brain tissue levels of neuronal apoptosis, BDNF expression, PLC activity, IP3 content, phospho- and total Ca2+/calmodulin-dependent protein kinase type IV (CaMKIV) expression, and phospho- and total cAMP response element binding protein (CREB) expression were also assayed. RESULTS PHZ-induced hemolytic hyperbilirubinemia was validated by significantly decreased serum hemoglobin and hematocrit as well as significantly increased total and direct serum bilirubin (p<0.05). Neonatal bilirubin-induced neurotoxicity was validated by significantly decreased serum BDNF, brain BDNF, and serum S100B, along with significantly increased serum tau protein (p<0.05). PHZ-induced hemolytic hyperbilirubinemia significantly decreased serum BDNF, brain BDNF, and PLC/IP3/Ca2+ pathway activation while increasing neuronal apoptosis levels (p<0.05), all of which were partially rescued by melatonin therapy (p<0.05). Pre-treatment with the PLC inhibitor U73122 largely abolished the positive effects of melatonin on PLC/IP3/Ca2+ pathway activation, downstream BDNF levels, and neuronal apoptosis (p<0.05). CONCLUSIONS Promotion of BDNF expression and anti-apoptotic effects in neonatal hemolytic hyperbilirubinemia by melatonin largely operates via a PLC-mediated mechanism.

Phototherapy for neonatal hyperbilirubinemia.

Approximately 60 years ago in England, phototherapy for neonatal hyperbilirubinemia was used in clinical practice. It was introduced in Japan approximately 50 years ago. At that time, the mechanism underlying the serum bilirubin concentration decrease by phototherapy was still unknown. The mechanism was identified by chemists, biochemists, and pediatricians. Clarification started with the report that unconjugated bilirubin was excreted into bile after photoirradiation in Gunn rats. After confirmation of the molecular structure of bilirubin on X-ray analysis, the mechanism for bile excretion of unconjugated bilirubin was verified based on geometric configurational photoisomers in the Gunn rat. Finally, the reaction and excretion of structural bilirubin photoisomers was proved to be the main mechanism for the decrease in serum bilirubin during phototherapy for neonatal hyperbilirubinemia, which differs from the mechanism in the Gunn rat. The most effective and safest light source and the optimal method to evaluate phototherapy, however, remain unknown. Moreover, as for bronze baby syndrome, which is a well-known adverse reaction to phototherapy, the etiology is unclear. Hence, we review phototherapy for hyperbilirubinemia including a fundamental understanding of the bilirubin photochemical reactions, and discuss the subclinical carcinogenic risk of phototherapy and the increased mortality rate of extremely low-birthweight infants due to aggressive phototherapy, which is becoming an increasing problem.

Decreased Glutathione S-transferase Level and Neonatal Hyperbilirubinemia Associated with Glucose-6-phosphate Dehydrogenase Deficiency: A Perspective Review.

Classically, genetically decreased bilirubin conjugation and/or hemolysis account for the mechanisms contributing to neonatal hyperbilirubinemia associated with glucose-6-phosphate dehydrogenase (G6PD) deficiency. However, these mechanisms are not involved in most cases of this hyperbilirubinemia. Additional plausible mechanisms for G6PD deficiency-associated hyperbilirubinemia need to be considered. Glutathione S-transferases (GST) activity depends on a steady quantity of reduced form of glutathione (GSH). If GSH is oxidized, it is reduced back by glutathione reductase, which requires the reduced form of nicotinamide adenine dinucleotide phosphate (NADPH). The main source of NADPH is the pentose phosphate pathway, in which G6PD is the first enzyme. Rat kidney GSH, rat liver GST, and human red blood cell GST levels have been found to positively correlate with G6PD levels in their respective tissues. As G6PD is expressed in hepatocytes, it is expected that GST levels would be significantly decreased in hepatocytes of G6PD-deficient neonates. As hepatic GST binds bilirubin and prevents their reflux into circulation, hypothesis that decreased GST levels in hepatocytes is an additional mechanism contributing to G6PD deficiency-associated hyperbilirubinemia seems plausible. Evidence for and against this hypothesis are discussed in this article hoping to stimulate further research on the role of GST in G6PD deficiency-associated hyperbilirubinemia.

Reduced Myelination and Increased Glia Reactivity Resulting from Severe Neonatal Hyperbilirubinemia.

Bilirubin-induced neurologic dysfunction (BIND) and kernicterus has been used to describe moderate to severe neurologic dysfunction observed in children exposed to excessive levels of total serum bilirubin (TSB) during the neonatal period. Here we use a new mouse model that targets deletion of the Ugt1 locus and the Ugt1a1 gene in liver to promote hyperbilirubinemia-induced seizures and central nervous system toxicity. The accumulation of TSB in these mice leads to diffuse yellow coloration of brain tissue and a marked cerebellar hypoplasia that we characterize as kernicterus. Histologic studies of brain tissue demonstrate that the onset of severe neonatal hyperbilirubinemia, characterized by seizures, leads to alterations in myelination and glia reactivity. Kernicterus presents as axonopathy with myelination deficits at different brain regions, including pons, medulla oblongata, and cerebellum. The excessive accumulation of TSB in the early neonatal period (5 days after birth) promotes activation of the myelin basic protein (Mbp) gene with an accelerated loss of MBP that correlates with a lack of myelin sheath formation. These changes were accompanied by increased astroglial and microglial reactivity, possibly as a response to myelination injury. Interestingly, cerebellum was the area most affected, with greater myelination impairment and glia burden, and showing a marked loss of Purkinje cells and reduced arborization of the remaining ones. Thus, kernicterus in this model displays not only axonal damage but also myelination deficits and glial activation in different brain regions that are usually related to the neurologic sequelae observed after severe hyperbilirubinemia.

Identification of neonatal haemolysis: an approach to predischarge management of neonatal hyperbilirubinemia.

AIM: Relative contributions of increased production [by end-tidal carbon monoxide concentrations (ETCOc)] and decreased elimination of bilirubin to predischarge hour-specific total bilirubin (TB) levels were assessed in healthy late-preterm and term newborns. Secondly, we report predischarge ETCOc ranges to guide clinical management of hyperbilirubinemia. METHODS: TB and ETCOc (≤3 timepoints) determinations of newborns aged between six hours and <6 days (n = 79) were stratified by postnatal age epochs. Hyperbilirubinemia risk was assessed by plotting TB values as a function of ETCOc. RESULTS: Stratifications of ETCOc (in ppm, mean, median and interquartile ranges) by postnatal age epochs (0-24, 24-48 and 48-72) were as follows: 2.0, 1.9, 1.8-2.2 (n = 11); 1.6, 1.5, 1.1-2.0 (n = 58); and 2.0, 1.8, 1.6-2.3 (n = 9), respectively. Infants with ETCOc ≥ 2.5 were at high risk, between 1.5 and 2.5 at moderate risk and ≤1.5 were at low risk. Risk due to haemolysis alone was not independent (p < 0.01). For infants with TB >75th percentile (n = 31), 23% had ETCO ≤1.5, and 77% had ETCOc > 1.5 (p < 0.00003). CONCLUSION: Near-simultaneous ETCOc and TB measurements in infants with TB >75th percentile accurately identify haemolytic hyperbilirubinemia.

An hour-specific transcutaneous bilirubin nomogram for Mongolian neonates.

UNLABELLED: Transcutaneous bilirubin (TcB) nomograms have been developed for different populations. However, the TcB level, rate of rise and peak varies among countries and ethnicities. The aim of this study was to establish an hour-specific TcB nomogram for healthy term and late preterm Mongolian neonates during the first 144 h after birth. A total of 5084 TcB measurements from 1297 healthy neonates (gestational age ≥35 weeks, birth weight ≥2000 g) were obtained from October 2012 to October 2013. All measurements were performed using the Jaundice Meter, the JM-103 at 6 to 144 postnatal hours. Mongolian infants had the following characteristics: 27.1 % were delivered by cesarean section, 17.8 % had a birth weight >4000 g, and >90 % were being breastfed. TcB percentiles for each designated time point were calculated for the development of an hour-specific nomogram. TcB levels increased most rapidly in the first 24 h and less rapidly from 24 to 78 h, reaching a plateau after 78 h for the 50th percentile. TcB levels of Mongolian neonates for each time point were higher than those of previous studies. CONCLUSION: The higher values of the TcB nomogram for Mongolian neonates may be due to their Asian ethnicity and exclusive breastfeeding. WHAT IS KNOWN: • TcB nomograms for neonatal jaundice screening have been established for many countries and ethnicities. The pattern of the TcB nomogram varies by country and ethnicity. What is New: • A TcB nomogram for neonates of Mongolian ethnicity at 6-144 postnatal hours was created and it had higher values than those in previous studies.

Usefulness of (1) H-MRS in differentiating bilirubin encephalopathy from severe hyperbilirubinemia in neonates.

PURPOSE: To evaluate the usefulness of (1) H-MRS in differentiating bilirubin encephalopathy from severe hyperbilirubinemia in neonates. MATERIALS AND METHODS: There were 11 patients enrolled in the neonatal bilirubin encephalopathy (NBE) group, 8 patients in the neonatal hyperbilirubinemia (NH) group, and 9 healthy, age-matched neonates were included as controls. All patients and controls underwent (1) H-MRS and conventional magnetic resonance (MR) sequences. The spectroscopic regions of interest were the bilateral basal ganglia and the thalamus, and a spatial resolution of 1.0 cm(3) was obtained. RESULTS: Peak-area ratios of NAA/Cr and NAA/ Cho in the basal ganglia were found to be significantly lower for the NBE group compared with the NH and control groups (P < 0.05). In contrast, there was no significant difference in the NAA/Cr ratios calculated for basal ganglia of the NH and control groups. Peak-area ratios of NAA/Cr and NAA/Cho in the thalamus were decreased for the NBE group compared with the NH and control groups, but the differences were not significant (P > 0.05). There was a significant correlation between NAA/Cr ratios for basal ganglia and the total serum bilirubin (TSB) peak level in the NBE group (P < 0.05). CONCLUSION: (1) H-MRS is useful in the differential diagnosis of NBE from severe hyperbilirubinemia in neonates, especially when the symptoms of NBE are atypical (subtle) and MRI does not reveal clear abnormalities.

Hour-specific nomogram for transcutaneous bilirubin in Japanese neonates.

BACKGROUND: The measurement of transcutaneous bilirubin (TcB) is very important to screen for hyperbilirubinemia in newborns. Until now, however, there has been no hour-specific, percentile-based TcB nomogram during the early neonatal period in Japanese neonates. The aim of this study was to develop a TcB nomogram within 72 h of birth in Japanese neonates. METHODS: A total of 3152 TcB measurements for 181 healthy Japanese neonates (gestational age ≥36 weeks, birthweight ≥2300 g) were obtained within 72 h of birth. All measurements were performed with a Konica Minolta jaundice meter, the JM-103. A nomogram curve was plotted to show the trend of TcB level over time. RESULTS: The nomogram curves rose almost linearly for all percentiles until 72 h after birth. CONCLUSION: An hour-specific, percentile-based TcB nomogram during the first 72 h after birth in Japanese neonates was successfully developed. Because Japanese neonates have higher and later peak bilirubin, an original hour-specific 97.5th percentile-based TcB nomogram may be needed to identify early-onset jaundice and manage neonatal hyperbilirubinemia.

The effect of phototherapy on fecal calprotectin levels.

OBJECTIVE: Fetal calprotectin levels increase in the early stages of necrotizing enterocolitis. Although the effects of several factors on fetal calprotectin have been studied, the effect of phototherapy is not known. In this study, we analyzed the effect of phototherapy on fetal calprotectin levels. METHODS: Ninety breast-fed newborns (46 male, 44 female) who were hospitalized for indirect hyperbilirubinemia and treated with phototherapy were included to the study. Forty-two of them were term and 44 of them were preterm. Newborns treated with phototherapy (n = 53) constituted the phototherapy group (29 preterm, 24 term) and 37 newborns who did not receive phototherapy (19 preterm, 18 term) constituted the control group. Fecal samples were collected 24 hours after phototherapy had been started. Fecal samples (100 mg) were weighed with sensitive scales and preserved at -80°C after buffering with a special solution. All samples were studied at the same time with a fecal calprotectin kit by using enzyme-linked immunosorbent assay. RESULTS: There were no statistically significant difference between fecal calprotectin levels of term and preterm babies who received phototherapy and babies who did not receive phototherapy. CONCLUSION: There was no effect of 24-hour phototherapy on fecal calprotectin levels in preterm and term newborns.

Bronze baby syndrome.

An in-depth review of jaundice in the newborn was covered in this column in the September/October 2007 issue. This article will include a brief review of bilirubin formation and discuss what is currently known about bronze baby syndrome (BBS). This column will include a short review of bilirubin formation and conclude with an unusual case study of a patient who developed BBS in the absence of direct hyperbilirubinemia.

[Neonatal hyperbilirubinemia and molecular mechanisms of jaundice]. / Vrozené hyperbilirubinemie a molekulární mechanizmy zloutenky.

The introductory summarises the classical path of heme degradation and classification of jaundice. Subsequently, a description of neonatal types of jaundice is given, known as Crigler Najjar, Gilberts, DubinJohnson and Rotor syndromes, emphasising the explanation of the molecular mechanisms of these metabolic disorders. Special attention is given to a recently discovered molecular mechanism of the Rotor syndrome. The mechanism is based on the inability of the liver to retrospectively uptake the conjugated bilirubin fraction primarily excreted into the blood, not bile. A reduced ability of the liver to uptake the conjugated bilirubin contributes to the development of hyperbilirubinemia in common disorders of the liver and bile ducts and to the toxicity of xenobiotics and drugs using transport proteins for conjugated bilirubin.

Risk factors for hyperbilirubinemia in breastfed term neonates.

UNLABELLED: Increased breastfeeding was suggested as a contributing factor to significant hyperbilirubinemia. The aim of this study was to identify the risk factors associated with jaundice in exclusively breastfed term neonates. We retrospectively reviewed all consecutively live-born neonates from August 2009 to July 2010 who had complete outpatient department (OPD) follow-up at ≤14 days old. Hyperbilirubinemia was defined as a transcutaneous bilirubin (TcB) value of ≥15 mg/dl. During the study period, there were 718 deliveries, of which 152 neonates were transferred to the special care nursery or neonatal intensive care unit; 566 neonates were discharged from the nursery, and 243 neonates were excluded: 83 did not return to the OPD, 46 were older than 14 days at OPD follow-up, 44 were <37 weeks of gestational age, and 70 had been fed formula. In total, 323 neonates were enrolled and classified into the hyperbilirubinemic (114 neonates) and non-hyperbilirubinemic groups (209 neonates). The gender, gestational age, Apgar score, age at nursery discharge, birth weight, and body weight at nursery discharge and at OPD were comparable between the two groups. TcB values at nursery discharge were positively correlated with TcB values in the OPD. Infants with hyperbilirubinemia exhibited significantly greater body weight loss from birth to the OPD follow-up and significantly less body weight gain from nursery discharge to OPD follow-up. CONCLUSION: High TcB values at nursery discharge and a smaller body weight gain are associated with hyperbilirubinemia in term neonates who are exclusively breastfed.

Inhibitory effect of 5ß-pregnane-3α,20ß-diol on transcriptional activity and enzyme activity of human bilirubin UDP-glucuronosyltransferase.

Prolonged unconjugated hyperbilirubinemia in infants associated with breast milk feeding is a common pediatric problem known as breast milk jaundice (BMJ). A polymorphic mutation (G71R) of bilirubin UDP-glucuronosyltransferase (UGT1A1) is a known cause of BMJ on the infantile side, but the responsible components of breast milk are not currently known. We analyzed the inhibitory effect of 5ß-pregnane-3α,20ß-diol (pregnanediol) on transcriptional activity and enzyme activity of UGT1A1. To this end, we constructed two types of expression vectors. One type comprised vectors including the upstream enhancer-promoter sequence of UGT1A1 for WT and variant type (-3279T>G with A(TA)7TAA), used in studying transcriptional regulation. The other type comprised vectors including cDNA of UGT1A1 for WT and the G71R variant, used in studying enzyme activity. In an in vitro expression study, pregnanediol did not affect the transcriptional activity of UGT1A1 enhancer-promoter complex of WT and variant type, even with coexistence of transcriptional factors such as constitutive androstane receptor or pregnane X receptor. In contrast, in the presence of 100 µM pregnanediol, bilirubin glucuronidation of G71R-UGT1A1 was reduced to 51% of WT. We suggest that pregnanediol is a cause of breast milk jaundice in carriers of G71R.

Transcutaneous bilirubin nomogram for predicting neonatal hyperbilirubinemia in healthy term and late-preterm Chinese infants.

Identifying infants that will develop significant hyperbilirubinemia with the risk of kernicterus, and planning appropriate follow-up strategies, is particularly challenging. In this study, 36,921 transcutaneous bilirubin (TcB) measurements were obtained from 6,035 healthy neonates (gestational age ≥ 35 weeks and birth weight ≥ 2,000 g) between January 1 and December 31, 2009. All measurements were performed with the JM-103 bilirubinometer at designated times between 0 and 168 postnatal hours. TcB percentiles were calculated and used to develop an hour-specific nomogram. The rate of increase in TcB was higher during the first 72 h of age, after which levels declined to a plateau by 72-108 h of age. We constructed a TcB nomogram by using the 40th, 75th, and 95th percentile values of TcB for every 12 h of the studied interval. The 75th percentile curve of the nomogram may be an ideal cutoff point for intensive follow-up of the neonate for hyperbilirubinemia as it carries very high sensitivity (78.7%) and negative predictive value (98.5%). The specificity (45.7%) and positive predictive value (15.5%) decreased to reach their lowest levels at the 40th percentile. Of the neonates in the high-risk zone, 167 (48.8%) infants had persistent subsequent hyperbilirubinemia post-discharge, compared with 292 (27.0%) infants in the high-intermediate-risk zone at discharge. One-hundred and seventeen (5.5%) infants in the low-intermediate-risk zone moved into the high-risk zone during follow-up. No newborn infants in the low-risk zone became high-risk during follow-up. We provide an hour-specific TcB nomogram to predict neonatal hyperbilirubinemia in healthy term and late-preterm Chinese infants.

Hyperbilirubinemia in the newborn.

After completing this article, readers should be able to: 1. List the risk factors for severe hyperbilirubinemia. 2. Distinguish between physiologic jaundice and pathologic jaundice of the newborn. 3. Recognize the clinical manifestations of acute bilirubin encephalopathy and the permanent clinical sequelae of kernicterus.4. Describe the evaluation of hyperbilirubinemia from birth through 3 months of age. 5. Manage neonatal hyperbilirubinemia, including referral to the neonatal intensive care unit for exchange transfusion.

Neuroprotection of taurine against bilirubin-induced elevation of apoptosis and intracellular free calcium ion in vivo.

Previous work has shown that taurine protected neurons against unconjugated bilirubin (UCB)-induced neurotoxicity by preventing cell apoptosis and maintaining intracellular Ca²âº homeostasis in primary neuron culture. This study investigates the neurotoxicity of hyperbilirubinemia and neuroprotection of taurine in a clinically relevant murine model in vivo. A hyperbilirubinemia baby mice model was established by intraperitoneal injection with UCB. After 24 h, the neural apoptotic level, transcriptional activity of caspase-3, and iCa²âº concentration were detected. It was found that UCB injection significantly increased both intracellular free Ca²âº concentrations and the activities of proapoptosis protease caspase-3, which is related to the elevation of neural apoptosis level. When baby mice were pretreated with 7.5 or 15 mg/kg body weight (bw) taurine for 4 h and then exposed to UCB, apoptotic death was significantly attenuated through down-regulation of activity of caspase-3 and i[Ca²âº] in the brain. From these observations, it was concluded that taurine limits bilirubin-induced neural damage by inhibiting iCa²âº overload as well as decreasing activation of proapoptotic proteases caspase-3. This study might contribute to the development of taurine as a broad-spectrum agent for preventing and/or treating neural damage in neonatal jaundice.

Variants of organic anion transporter polypeptide 2 gene are not risk factors associated with severe neonatal hyperbilirubinemia.

OBJECTIVES: This study aimed to determine the prevalence of four variants of organic anion transporter polypeptide 2 (OATP2) gene, and their association with severe hyperbilirubinemia. DESIGN: Observational study. SETTING: A tertiary university unit. PATIENTS: Term infants of Chinese descent. METHODS: 175 infants, consisting of 65 admitted for treatment of severe hyperbilirubinemia (with serum bilirubin levels > 250 mmol/L at age 1-2 days or > 300 micromol/L at age > or = 3 days) and 110 randomly selected inborn infants without severe hyperbilirubinemia during their first month of life, were recruited. Their blood samples were subjected to sequencing analysis of exon 4 and exon 5 of OATP2 gene for detection of c.388A > G, c.521T > C, c.571T > C and c.597C > T variants. RESULTS: The c.388A > G variant was the most common, and the c.521 T > C was least common, being present in 90.9% and 26.9% of the infants, respectively. Forward logistic regression analysis showed that the only significant risk factors associated with severe hyperbilirubinemia among these Chinese infants were: exclusive breast feeding (adjusted odds ratio (OR) = 12.5, 95% C.I.: 2.9, 53.4; p = 0.001), infants with homozygous 211 variant of the UDPG 1A1 gene (adjusted OR = 37.7, 95% C.I.: 4.4, 324.1; p = 0.001), and G6PD enzyme level < 8.5 IU/g Hb (adjusted OR = 7.3, 95% C.I.: 3.1, 17.5; p < 0.00001). Gestational age, G6PD mutation status, actual G6PD enzyme level, and the 4 variants of the OATP2 gene mutation were not significant risk factors. CONCLUSION: Variants of OATP2 gene were not significant risk factors associated with severe hyperbilirubinemia in Malaysian Chinese infants.