Hyperbilirubinemia and kernicterus

Evaluating the relationship between aEEG findings and two-year prognosis in neonates with severe hyperbilirubinemia

OBJECTIVE

Identifying factors that can better predict the prognosis of neonates with hyperbilirubinemia is important. In this study, we aimed to evaluate the relationship between electroencephalography (EEG) findings and two-year prognosis in neonates with severe hyperbilirubinemia.

METHODS & MATERIALS

In a cohort prospective study, we studied neonates with a total serum bilirubin level of higher than 18 mg/dL, who were admitted to the neonatal intensive care unit (NICU) of Ghaem hospital, Mashhad, Iran. EEG was recorded upon admission, for all neonates. Patients' data, including demographic characteristics, admission information, and pregnancy and birth data were gathered by obtaining history from parents and studying case files. Also, the relationship between initial EEG findings and final developmental status was assessed.

RESULTS

Mean and standard deviation age of patients were 5.46 ± 3.13 days and average serum total bilirubin level was 23.97 ± 4.34 mg/dL at admission. Our findings revealed a significant correlation between the presence of trace alternant on EEG and developmental delay (P = .001). Presence of trace alternant waves on initial EEG at admission was significantly associated with developmental delay in the two year (P = .005).

CONCLUSION

These results indicate a relationship between developmental prognosis and the severity of hyper bilirubinemia in neonates. Also, our findings show that the presence of trace alternate waves on the initial EEG is significantly associated with developmental delay of the neonate in the future.

Portosystemic shunt placement reveals blood signatures for the development of hepatic encephalopathy through mass spectrometry

Elective transjugular intrahepatic portosystemic shunt (TIPS) placement can worsen cognitive dysfunction in hepatic encephalopathy (HE) patients due to toxins, including possible microbial metabolites, entering the systemic circulation. We conducted untargeted metabolomics on a prospective cohort of 22 patients with cirrhosis undergoing elective TIPS placement and followed them up to one year post TIPS for HE development. Here we suggest that pre-existing intrahepatic shunting predicts HE severity post-TIPS. Bile acid levels decrease in the peripheral vein post-TIPS, and the abundances of three specific conjugated di- and tri-hydroxylated bile acids are inversely correlated with HE grade. Bilirubins and glycerophosphocholines undergo chemical modifications pre- to post-TIPS and based on HE grade. Our results suggest that TIPS-induced metabolome changes can impact HE development, and that pre-existing intrahepatic shunting could be used to predict HE severity post-TIPS.

Pre- and Post-Portosystemic Shunt Placement Metabolomics Reveal Molecular Signatures for the Development of Hepatic Encephalopathy

Hepatic encephalopathy (HE) is a common complication of advanced liver disease causing brain dysfunction. This is likely due to the accumulation of unfiltered toxins within the bloodstream. A known risk factor for developing or worsening HE is the placement of a transjugular intrahepatic portosystemic shunt (TIPS), which connects the pre-hepatic and post-hepatic circulation allowing some blood to bypass the dysfunctional liver and decreases portal hypertension. To better understand the pathophysiology of post-TIPS HE, we conducted a multi-center prospective cohort study employing metabolomic analyses on hepatic vein and peripheral vein blood samples from participants with cirrhosis undergoing elective TIPS placement, measuring chemical modifications and changes in concentrations of metabolites resulting from TIPS placement. In doing so, we identified numerous alterations in metabolites, including bile acids, glycerophosphocholines, and bilirubins possibly implicated in the development and severity of HE.

Cord blood albumin as a predictor of neonatal jaundice

Background and Aim

Bilirubin can have a toxic effect on the brain, so newborns must be carefully checked to identify those who may develop significant hyperbilirubinemia and bilirubin encephalopathy (kernicterus). The study aimed to determine if cord blood albumin could be utilized to predict the onset of significant newborn jaundice in healthy-term babies.

Patients and Methods

A cohort study was carried out in AL-Zahraa teaching hospital in AL-Najaf city during the period from January 1 to November 1, 2020. A randomized 100 full-term healthy neonates were enrolled. A blood sample was drawn by milking the cord and sent for serum albumin estimation. Patients were then followed up on the third and fifth days of life for total serum bilirubin (TSB).

Results

Out of 100 healthy-term neonates that were included in this study, 60 of them had low cord blood albumin (<2.8 g/dl), and 40 of them had normal cord blood albumin (≥2.8 g/dl) with an age range of 1-5 days. There is a statistically significant difference between low cord blood albumin and significant neonatal jaundice on the third day with a 5 times more risk of developing significant jaundice than neonates with normal cord blood albumin.

Conclusion

Cord blood albumin levels are sensitive to predicting subsequent neonatal jaundice in the healthy term newborn.

Bilirubin Encephalopathy

PURPOSE OF REVIEW

Hyperbilirubinemia is commonly seen in neonates. Though hyperbilirubinemia is typically asymptomatic, severe elevation of bilirubin levels can lead to acute bilirubin encephalopathy and progress to kernicterus spectrum disorder, a chronic condition characterized by hearing loss, extrapyramidal dysfunction, ophthalmoplegia, and enamel hypoplasia. Epidemiological data show that the implementation of universal pre-discharge bilirubin screening programs has reduced the rates of hyperbilirubinemia-associated complications. However, acute bilirubin encephalopathy and kernicterus spectrum disorder are still particularly common in low- and middle-income countries.

RECENT FINDINGS

The understanding of the genetic and biochemical processes that increase the susceptibility of defined anatomical areas of the central nervous system to the deleterious effects of bilirubin may facilitate the development of effective treatments for acute bilirubin encephalopathy and kernicterus spectrum disorder. Scoring systems are available for the diagnosis and severity grading of these conditions. The treatment of hyperbilirubinemia in newborns relies on the use of phototherapy and exchange transfusion. However, novel therapeutic options including deep brain stimulation, brain-computer interface, and stem cell transplantation may alleviate the heavy disease burden associated with kernicterus spectrum disorder. Despite improved screening and treatment options, the prevalence of acute bilirubin encephalopathy and kernicterus spectrum disorder remains elevated in low- and middle-income countries. The continued presence and associated long-term disability of these conditions warrant further research to improve their prevention and management.

Oridonin alleviates hyperbilirubinemia through activating LXRα-UGT1A1 axis

Hyperbilirubinemia is a serious hazard to human health due to its neurotoxicity and lethality. So far, successful therapy for hyperbilirubinemia with fewer side effects is still lacking. In this study, we aimed to clarify the effects of oridonin (Ori), an active diterpenoid extracted from Rabdosia rubescens, on hyperbilirubinemia and revealed the underlying molecular mechanism in vivo and in vitro. Here, we showed that liver X receptor alpha (LXRα) deletion eliminated the protective effect of Ori on phenylhydrazine hydrochloride-induced hyperbilirubinemia mice, indicating that LXRα acted as a key target for Ori treatment of hyperbilirubinemia. Ori significantly increased the expression of LXRα and UDP-glucuronosyltransferase 1A1 (UGT1A1) in the liver of wild-type (WT) mice, which were lost in LXRα^-/- mice. Ori or LXR agonist GW3965 also reduced lipopolysaccharide/D-galactosamine-induced hyperbilirubinemia via activating LXRα/UGT1A1 in WT mice. Liver UGT1A1 enzyme activity was elevated by Ori or GW3965 in WT mice. Further, Ori up-regulated LXRα gene expression, increased its nuclear translocation and stimulated UGT1A1 promoter activity in HepG2 cells. After silencing LXRα by siRNA, Ori-induced UGT1A1 expression was markedly reduced in HepG2 cells and primary mouse hepatocytes. Taken together, Ori stimulated the transcriptional activity of LXRα, resulting in the up-regulation of UGT1A1. Therefore, Ori or its analogs might have the potential to treat hyperbilirubinemia-related diseases through modulating LXRα-UGT1A1 signaling.

Is it necessary to give calcium infusion during the exchange transfusion in newborns?

OBJECTIVES

We aimed to evaluate total serum calcium (TSC) and ionized serum calcium (ISC) levels and their effects on clinical outcomes in neonates underwent exchange transfusion (ET).

METHOD

In this study, the data of newborn infants who underwent ET due to hyperbilirubinemia in a third level neonatal intensive care unit (NICU) were retrospectively analyzed. The patients were monitored by electrocardiogram during ET. Cardiac and respiratory rates, peripheral oxygen saturation, blood pressure values ​​and clinical findings as convulsion, tremor, hypertonia, laryngospasm, cyanosis and apnea were recorded in ET observation forms. The infants with no symptoms of hypocalcemia during the procedure were not routinely given IV calcium gluconate. TSC and ISC measured at the beginning, at the end and 24 h after the end of ET were evaluated retrospectively.

RESULTS

Data of 36 newborn patients were evaluated. Median gestational age was 39 (35-40) weeks, mean birthweight was 2840 ± 841 (mean ± SD) grams. During the ET, desaturation was observed in five patients(13.9 %), sinus bradycardia in six(16.7 %), tachypnea in two(5.5 %), sinus tachycardia in one(2.8 %), and rare ventricular extrasystoles in one(2.8 %). Hypocalcaemia was not detected in any of the patients at the beginning of ET. Hypocalcemia was observed in two cases (5.5 %) at the end of ET. There was no statistically significant difference between the TSC and ISC levels at the beginning of ET, at the end and at the end of 24 h.

CONCLUSION

As a result, routine intravenous (IV) calcium administration seems to be unnecessary provided that vital signs and neurological status are closely monitored during ET.

Amplitude of low-frequency fluctuation may be an early predictor of delayed motor development due to neonatal hyperbilirubinemia: a fMRI study

BACKGROUND

Acute bilirubin encephalopathy or kernicterus is the worst consequence of brain damage caused by the elevation of total unbound serum bilirubin (TSB) in neonates. The present study aimed to visualize the characteristic brain regions of neonates with hyperbilirubinemia (HB) using functional magnetic resonance imaging (fMRI) and to measure the amplitude of low-frequency fluctuation (ALFF) values.

METHODS

This was a prospective cohort study, which included newborns with HB who were hospitalized at the Children's Hospital of Fudan University. The control group included neonates admitted with neonatal simple wet lung or pneumonia without neurological disease or brain injury. Newborns were divided into a severe hyperbilirubinemia group (SHB), moderate HB group, and control group based on TSB levels. The newborns completed routine MRI combined with fMRI scans and brainstem auditory evoked potentials (BAEPs) during their hospitalization.

RESULTS

A total of 251 newborns were included in this study. There were 45 patients in the SHB group, 65 in the HB group, and 141 in the control group. The average ALFF value in the basal ganglia region in the SHB group was the highest, which was greater than that in the HB and control groups (P<0.001). The ALFF increased with an increase in TSB concentration. Based on the results of the Bayley Scales of infant development assessment, we further found that the most significant difference in ALFF remained in the basal ganglia region between newborns with motor development scores above 70 (including 70) and below 70. Correlation analysis revealed a strong negative correlation between motor development scores and ALFF (r=-0.691, P<0.001). When ALFF alone was used to predict motor development, the sensitivity was 89%. When ALFF was combined with TSB and BEAP results, the area under the ROC curve was the largest (AUC =0.85). The sensitivity and specificity of the model were 67.86% and 90.77%, respectively.

CONCLUSIONS

The ALFF value may be able to serve as an early imaging biomarker and has a greater sensitivity than TSB or BAEP results in predicting long-term motor development (18 m) in HB.

Repurposing Immunomodulatory Imide Drugs (IMiDs) in Neuropsychiatric and Neurodegenerative Disorders

Neuroinflammation represents a common trait in the pathology and progression of the major psychiatric and neurodegenerative disorders. Neuropsychiatric disorders have emerged as a global crisis, affecting 1 in 4 people, while neurological disorders are the second leading cause of death in the elderly population worldwide (WHO, 2001; GBD 2016 Neurology Collaborators, 2019). However, there remains an immense deficit in availability of effective drug treatments for most neurological disorders. In fact, for disorders such as depression, placebos and behavioral therapies have equal effectiveness as antidepressants. For neurodegenerative diseases such as Parkinson's disease and Alzheimer's disease, drugs that can prevent, slow, or cure the disease have yet to be found. Several non-traditional avenues of drug target identification have emerged with ongoing neurological disease research to meet the need for novel and efficacious treatments. Of these novel avenues is that of neuroinflammation, which has been found to be involved in the progression and pathology of many of the leading neurological disorders. Neuroinflammation is characterized by glial inflammatory factors in certain stages of neurological disorders. Although the meta-analyses have provided evidence of genetic/proteomic upregulation of inflammatory factors in certain stages of neurological disorders. Although the mechanisms underpinning the connections between neuroinflammation and neurological disorders are unclear, and meta-analysis results have shown high sensitivity to factors such as disorder severity and sample type, there is significant evidence of neuroinflammation associations across neurological disorders. In this review, we summarize the role of neuroinflammation in psychiatric disorders such as major depressive disorder, generalized anxiety disorder, post-traumatic stress disorder, and bipolar disorder, as well as in neurodegenerative disorders, such as Parkinson's disease and Alzheimer's disease, and introduce current research on the potential of immunomodulatory imide drugs (IMiDs) as a new treatment strategy for these disorders.

Hemolysis due to Alpha-Hemolytic Enterococcus Urinary Infection: A Rare Cause of Early and Severe Unconjugated Hyperbilirubinemia in a Neonate

The reason for reporting this case is to remind that some microorganisms may cause hemolysis leading to early and severe hyperbilirubinemia by secreting hemolysin in cases; where bilirubin levels cannot be successfully decreased despite effective phototherapy, intravenous immunoglobulin, and even exchange transfusion, or in cases of increased rebound bilirubin (although urinary tract infection is associated with increased conjugated bilirubin fraction and prolonged jaundice). The most common causes of hemolysis are ABO/Rh incompatibility and enzyme deficiencies such as glucose-6-phosphate dehydrogenase (G6PDH), pyruvate kinase (PK), and galactose-1-phosphate uridyltransferase (GALT). Our patient was a male infant, weighing 3,160 g, at 38 + 4 gestational week; he was referred to our unit with total bilirubin level of 14.7 mg/dL recorded at the postnatal 20th hour and was initiated treatment with intensive phototherapy and prepared for exchange transfusion. The G6PD, PK, and GALT enzyme levels studied at the postnatal 96th hour and reducing substances in urine were detected to be normal/negative, whereas complete urinalysis revealed pyuria (7 leukocytes per each high power field). α-hemolysis-producing 105 colony-forming unit/mL Enterobacter cloacae grew on blood agar in the urine culture. As reported in our case, hemolysin-secreting α and β-hemolytic bacteria can lead to severe and early hemolysis and unconjugated hyperbilirubinemia, as in blood type incompatibility and enzyme deficiencies.

Exchange transfusion for neonatal hyperbilirubinemia: A multicenter, prospective study of Turkish Neonatal Society

Objective

The frequency of neonatal exchange transfusion has declined in recent years, but is still performed in many countries. The procedure is associated with complications. The aim of the study was to determine the clinical features and etiologies of infants with hyperbilirubinemia who underwent exchange transfusion and evaluate the adverse events and clinical outcomes.

Material and Methods

We performed a secondary analysis of the multicenter Turkish Neonatal Jaundice Online Registry data. Otherwise healthy newborns born ≥35 weeks of gestation who were hospitalized for jaundice and underwent exchange transfusion were included.

Results

One-hundred thirty-two patients with a mean serum bilirubin level on admission of 24.9±9.1 mg/dL were enrolled in the study. The most common cause for exchange transfusion was hemolytic jaundice (63.6%), followed by lack of proper feeding (12.9%). It was found that the infants with lack of proper feeding were discharged earlier from the maternity ward (p=0.02), but they were admitted to hospital later (p<0.001) with a higher bilirubin level (p=0.001), and geater weight loss (p=0.04). The reported rate of adverse events associated with exchange transfusion was 11.4%. The most common complication was thrombocytopenia (40%). None of the infants died during the procedure. Acute bilirubin encephalopathy was reported in 13 (9.8%) patients.

Conclusion

Severe hyperbilirubinemia requiring exchange transfusion and acute bilirubin encephalopathy are still challenging problems in neonatal periodin our country. The policies including blood group analysis of pregnant women, programs informing parents about breastfeeding and jaundice, and monitoring bilirubin levels of high-risk newborns should be developed to reduce the necessitating for exchange transfusion and to avoid related complications.

A Neglected and Promising Predictor of Severe Hyperbilirubinemia Due to Hemolysis: Carboxyhemoglobin

Aims: We investigated the relationship between total serum bilirubin (TSB) and carboxyhemoglobin (COHb) in term neonates with detected and treated hemolysis within a particular time frame with the aim of augmenting the case for early diagnosis and prevention of morbidity in hemolysis. Materials and Methods: The study group comprised term newborns who were above the 95th percentile for TSB, underwent intravenous immunoglobulin (IVIG) or applied total exchange transfusion due to hemolysis. Newborns without hemolysis who were above the 95th TSB percentile and required phototherapy comprised the control group. Results: At a cutoff COHb value of 2.2%, 80.8% sensitivity, 95.5% specificity, 18.1 likelihood ratio, positive predictive value of 94.7%, and negative predictive value of 83.2% were identified. Conclusion: We found that COHb is a sensitive and specific method for detecting hemolysis, and it can be used in the early diagnosis of hemolytic diseases causing early and severe hyperbilirubinemia.

Case study on the use of intensive pediatric neurorehabilitation in the treatment of kernicterus

Background

Kernicterus Spectrum Disorder (KSD) is the result of prolonged bilirubin toxicity resulting in widespread neurological injury. Once the bilirubin levels are normalized the encephalopathy becomes static, however the consequences of the injury can have life-long effects. The sequelae of KSD include motor impairments, auditory deficits, dental dysplasia, and potentially cognitive impairments. While KSD is a rare diagnosis, particularly in developed countries, there is evidence that there may be a global increase in incidence (Hansen, Semin Neonatol 7:103–9, 2002; Johnson, J Perinatol 29:S25–45, 2009; Kaplan etal. Neonatology 100:354–62, 2011; Maisels, Early Hum Dev 85:727–32, 2009; Olusanya etal., Arch Dis Child 99:1117–21, 2014; Steffensrud, Newborn Infant Nurs Rev 4:191–200, 2004). The literature on the treatment of various specific sequelae of KSD is varied, but in general specific therapeutic efforts to improve motor skills are not evidenced-based. The following is a case report on the use of Acquire therapy, an intensive neuromotor intervention, to ameliorate some of the motor-function deficits secondary to KSD.

Case presentation

This case-report presents the results of two intensive therapeutic intervention sessions in one male child with KSD. Treatments occurred at 28 and 34 months. The child presented with fine and gross motor deficits as well as communication delays. Each session consisted of daily therapy for 4 h each weekday for 3 weeks. The child was assessed before and after treatment with 2 standardized measures, the Gross Motor Function Measure (GMFM) and The Bayley Scales of Infant and Toddler Development (Bayley).

Conclusions

The GMFM at the 1st assessment was 34, 74at the 2nd assessment (after intervention 1), and 64 at the third assessment and 104 at the 4th assessment (after intervention 2). The Bayley at the 3rd assessment was 18, and 38 at the 4th assessment (after intervention 2).

Review of bilirubin neurotoxicity I: molecular biology and neuropathology of disease

Despite the availability of successful prevention strategies to prevent excessive hyperbilirubinemia, the neurological sequelae of bilirubin neurotoxicity (BNTx) still occur throughout the world. Kernicterus, encephalopathy due to BNTx, is now understood to be a spectrum of severity and phenotypes known as kernicterus spectrum disorder (KSD). A better understanding of the selective neuropathology and molecular biology of BNTx and using consistent clinical definitions of KSDs as outcome measure can lead to more accurately predicting the risk and causes of BNTx and KSDs. In Part I of our two-part review, we will summarize current and recent advances in the understanding of the selective neuropathology and molecular biology of the disease. Herein we emphasize the role of unbound, free unconjugated bilirubin as well as genetic contributions to the susceptibility BNTx and the development of KSDs. In Part II, we focus on current and possible novel methods to prevent BNTx and ABE and treat ABE and KSDs.

Bilirubin-Induced Oxidative Stress Leads to DNA Damage in the Cerebellum of Hyperbilirubinemic Neonatal Mice and Activates DNA Double-Strand Break Repair Pathways in Human Cells

Unconjugated bilirubin is considered a potent antioxidant when present at moderate levels. However, at high concentrations, it produces severe neurological damage and death associated with kernicterus due to oxidative stress and other mechanisms. While it is widely recognized that oxidative stress by different toxic insults results in severe damage to cellular macromolecules, especially to DNA, no data are available either on DNA damage in the brain triggered by hyperbilirubinemia during the neonatal period or on the activation of DNA repair mechanisms. Here, using a mouse model of neonatal hyperbilirubinemia, we demonstrated that DNA damage occurs in vivo in the cerebellum, the brain region most affected by bilirubin toxicity. We studied the mechanisms associated with potential toxic action of bilirubin on DNA in in vitro models, which showed significant increases in DNA damage when neuronal and nonneuronal cells were treated with 140 nM of free bilirubin (Bf), as determined by γH2AX Western blot and immunofluorescence analyses. Cotreatment of cells with N-acetyl-cysteine, a potent oxidative-stress inhibitor, prevented DNA damage by bilirubin, supporting the concept that DNA damage was caused by bilirubin-induced oxidative stress. Bilirubin treatment also activated the main DNA repair pathways through homologous recombination (HR) and nonhomologous end joining (NHEJ), which may be adaptive responses to repair bilirubin-induced DNA damage. Since DNA damage may be another important factor contributing to neuronal death and bilirubin encephalopathy, these results contribute to the understanding of the mechanisms associated with bilirubin toxicity and may be of relevance in neonates affected with severe hyperbilirubinemia.

Neuroinflammation and ER-stress are key mechanisms of acute bilirubin toxicity and hearing loss in a mouse model

Hyperbilirubinemia (jaundice) is caused by raised levels of unconjugated bilirubin in the blood. When severe, susceptible brain regions including the cerebellum and auditory brainstem are damaged causing neurological sequelae such as ataxia, hearing loss and kernicterus. The mechanism(s) by which bilirubin exerts its toxic effect have not been completely understood to date. In this study we investigated the acute mechanisms by which bilirubin causes the neurotoxicity that contributes to hearing loss. We developed a novel mouse model that exhibits the neurological features seen in human Bilirubin-Induced Neurological Dysfunction (BIND) syndrome that we assessed with a behavioural score and auditory brainstem responses (ABR). Guided by initial experiments applying bilirubin to cultured cells in vitro, we performed whole genome gene expression measurements on mouse brain tissue (cerebellum and auditory brainstem) following bilirubin exposure to gain mechanistic insights into biochemical processes affected, and investigated further using immunoblotting. We then compared the gene changes induced by bilirubin to bacterial lipopolysaccharide (LPS), a well characterized inducer of neuroinflammation, to assess the degree of similarity between them. Finally, we examined the extent to which genetic perturbation of inflammation and both known and novel anti-inflammatory drugs could protect hearing from bilirubin-induced toxicity. The in vitro results indicated that bilirubin induces changes in gene expression consistent with endoplasmic reticulum (ER) stress and activation of the unfolded protein response (UPR). These gene changes were similar to the gene expression signature of thapsigargin–a known ER stress inducer. It also induced gene expression changes associated with inflammation and NF-κB activation. The in vivo model showed behavioural impairment and a raised auditory threshold. Whole genome gene expression analysis confirmed inflammation as a key mechanism of bilirubin neurotoxicity in the auditory pathway and shared gene expression hallmarks induced by exposure to bacterial lipopolysaccharide (LPS) a well-characterized inducer of neuroinflammation. Interestingly, bilirubin caused more severe damage to the auditory system than LPS in this model, but consistent with our hypothesis of neuroinflammation being a primary part of bilirubin toxicity, the hearing loss was protected by perturbing the inflammatory response. This was carried out genetically using lipocalin-2 (LCN2)-null mice, which is an inflammatory cytokine highly upregulated in response to bilirubin. Finally, we tested known and novel anti-inflammatory compounds (interfering with NF-κB and TNFα signalling), and also demonstrated protection of the auditory system from bilirubin toxicity. We have developed a novel, reversible, model for jaundice that shows movement impairment and auditory loss consistent with human symptoms. We used this model to establish ER-stress and inflammation as major contributors to bilirubin toxicity. Because of the rapid and reversible onset of toxicity in this novel model it represents a system to screen therapeutic compounds. We have demonstrated this by targeting inflammation genetically and with anti-inflammatory small molecules that offered protection against bilirubin toxicity. This also suggests that anti-inflammatory drugs could be of therapeutic use in hyperbilirubinemia.

Biliverdin Reductase inhibitors did not improve severe unconjugated hyperbilirubinemia in vivo

We aimed to identify potent biliverdin reductase (BVRA) inhibitors as a novel concept for the treatment of severe unconjugated hyperbilirubinemia. 1280 FDA-approved compounds were screened in vitro for their ability to inhibit human and rat BVRA activity and 26 compounds were identified as BVRA inhibitors. Montelukast and Disulfiram were selected as potentially clinically applicable drugs and tested to reduce serum unconjugated bilirubin (UCB) levels in the Ugt1a1-deficient rat, a model for chronic unconjugated hyperbilirubinemia. Oral administration of Disulfiram was toxic in the Ugt1a1-deficient rat (weight loss, transaminase elevation). Oral Montelukast administration led to low serum concentrations and did not alter serum UCB levels. Intraperitoneal injections of Montelukast resulted in concentrations up to 110 μmol/L in serum and 400 μmol/L in the liver. Still, serum UCB levels remained unaltered. This first study on biliverdin reductase inhibition as a novel concept for treatment of unconjugated hyperbilirubinemia identified putative in vitro BVRA inhibitors. Montelukast, the clinically most suitable inhibitor, did not result in reduction of serum UCB in the Ugt1a1-deficient rat. The proposed treatment strategy will not result in amelioration of severe unconjugated hyperbilirubinemia in humans without the identification or development of more potent BVRA inhibitors.

Therapeutic Plasma Exchange in Neonates and Infants: Successful Use of a Miniaturized Machine

Therapeutic plasma exchange (TPE) in neonates and small infants is a treatment method at the forefront that may become a potentially life-saving procedure in a wide array of severe conditions. Indications for TPE in the pediatric population have been mainly derived from adult literature, with neonatal hyperbilirubinemia being the most notable exception. The only alternative to TPE in small pediatric patients is manual blood exchange transfusion, which, however, bears an unacceptably high risk of severe complications. Still, technical issues due to extracorporeal circulation in neonates have burdened TPE so far, since machines developed for adults require a relatively large blood volume to operate. We in this study, describe our preliminary experience of TPE for treating 2 potentially life-threatening conditions in neonatal age. To overcome the aforementioned limitations, plasmapheresis was performed in both cases using a machine specifically designed for patients weighing less than 10 kg.

Developmental, Genetic, Dietary, and Xenobiotic Influences on Neonatal Hyperbilirubinemia

Hyperbilirubinemia, caused by the accumulation of unconjugated bilirubin, is one of the most common clinical diagnoses in both premature and term newborns. Owing to the fact that bilirubin is metabolized solely through glucuronidation by UDP-glucuronosyltransferase (UGT) 1A1, it is now known that immaturity of UGT1A1, in combination with the overproduction of bilirubin during the developmental stage, acts as a bottleneck to bilirubin elimination and predisposes the infant to high total serum bilirubin levels. Although neonatal jaundice is mostly benign, excessively high levels of serum bilirubin in a small percentage of newborns can cause bilirubin-induced neurologic dysfunction, potentially leading to permanent brain damage, a condition known as kernicterus Although a large portion of hyperbilirubinemia cases in newborns are associated with hemolytic diseases, we emphasize here the impaired ability of UGT1A1 to eliminate bilirubin that contributes to hyperbilirubinemia-induced neurotoxicity in the developmental stage. As a series of hereditary UGT1A1 mutations have been identified that are associated with UGT1A1 deficiency, new evidence has verified that delayed expression of UGT1A1 during the early stages of neonatal development is a tightly controlled event involving coordinated intrahepatic and extrahepatic regulation. This review recapitulates the progress that has been made in recent years in understanding the causes and physiopathology of severe hyperbilirubinemia, investigating molecular mechanisms underlying bilirubin-induced encephalopathy, and searching for potential therapies for treating pathologic hyperbilirubinemia. Several animal models have been developed to make it possible to examine bilirubin-induced neurotoxicity from multiple directions. Moreover, environmental factors that may alleviate or worsen the condition of hyperbilirubinemia are discussed.

A Hypothesis for Using Pathway Genetic Load Analysis for Understanding Complex Outcomes in Bilirubin Encephalopathy

Genetic-based susceptibility to bilirubin neurotoxicity and chronic bilirubin encephalopathy (kernicterus) is still poorly understood. Neonatal jaundice affects 60–80% of newborns, and considerable effort goes into preventing this relatively benign condition from escalating into the development of kernicterus making the incidence of this potentially devastating condition very rare in more developed countries. The current understanding of the genetic background of kernicterus is largely comprised of mutations related to alterations of bilirubin production, elimination, or both. Less is known about mutations that may predispose or protect against CNS bilirubin neurotoxicity. The lack of a monogenetic source for this risk of bilirubin neurotoxicity suggests that disease progression is dependent upon an overall decrease in the functionality of one or more essential genetically controlled metabolic pathways. In other words, a “load” is placed on key pathways in the form of multiple genetic variants that combine to create a vulnerable phenotype. The idea of epistatic interactions creating a pathway genetic load (PGL) that affects the response to a specific insult has been previously reported as a PGL score. We hypothesize that the PGL score can be used to investigate whether increased susceptibility to bilirubin-induced CNS damage in neonates is due to a mutational load being placed on key genetic pathways important to the central nervous system's response to bilirubin neurotoxicity. We propose a modification of the PGL score method that replaces the use of a canonical pathway with custom gene lists organized into three tiers with descending levels of evidence combined with the utilization of single nucleotide polymorphism (SNP) causality prediction methods. The PGL score has the potential to explain the genetic background of complex bilirubin induced neurological disorders (BIND) such as kernicterus and could be the key to understanding ranges of outcome severity in complex diseases. We anticipate that this method could be useful for improving the care of jaundiced newborns through its use as an at-risk screen. Importantly, this method would also be useful in uncovering basic knowledge about this and other polygenetic diseases whose genetic source is difficult to discern through traditional means such as a genome-wide association study.

Bilirubin-Induced Audiologic Injury in Preterm Infants

Although hyperbilirubinemia is extremely common among neonates and is usually mild and transient, it sometimes leads to bilirubin-induced neurologic damage (BIND). The auditory pathway is highly sensitive to the effects of elevated total serum/plasma bilirubin (TB) levels, with damage manifesting clinically as auditory neuropathy spectrum disorder. Compared to full-term neonates, preterm neonates are more susceptible to BIND and suffer adverse effects at lower TB levels with worse long-term outcomes. Furthermore, although standardized guidelines for management of hyperbilirubinemia exist for term and late preterm neonates, similar guidelines for neonates less than 35 weeks gestational age are limited.

Audiologic impairment associated with bilirubin-induced neurologic damage

Hyperbilirubinemia occurs commonly in neonates and is usually mild and transient, with no long-lasting sequelae. However, bilirubin-induced neurologic damage may occur in some infants. The auditory pathway is the most sensitive part of the central nervous system to bilirubin-induced toxicity, and permanent sequelae may result from only moderately elevated total serum/plasma bilirubin levels. The damage to the auditory system occurs primarily within the brainstem and cranial nerve VIII, and manifests clinically as auditory neuropathy spectrum disorder.

Movement disorders due to bilirubin toxicity

Advances in the care of neonatal hyperbilirubinemia have led to a decreased incidence of kernicterus. However, neonatal exposure to high levels of bilirubin continues to cause severe motor symptoms and cerebral palsy (CP). Exposure to moderate levels of unconjugated bilirubin may also cause damage to the developing central nervous system, specifically the basal ganglia and cerebellum. Brain lesions identified using magnetic resonance imaging following extreme hyperbilirubinemia have been linked to dyskinetic CP. Newer imaging techniques, such as diffusion tensor imaging or single-photon emission computed tomography, allow quantification of more subtle white matter injury following presumed exposure to unbound bilirubin, and may explain more subtle movement disorders. New categories of bilirubin-induced neurologic dysfunction, characterized by subtle bilirubin encephalopathy following moderate hyperbilirubinemia, have been implicated in long-term motor function. Further research is needed to identify subtle impairments resulting from moderate-severe neonatal hyperbilirubinemia, to understand the influence of perinatal risk factors on bilirubin toxicity, and to develop neuroprotective treatment strategies to prevent movement disorders due to bilirubin toxicity.

End-tidal carbon monoxide and hemolysis

Hemolytic disease in newborns can result from a number of conditions, which can place such infants at an increased risk for the development of severe hyperbilirubinemia. Because the catabolism of heme produces equimolar amounts of carbon monoxide (CO) and bilirubin, measurements of end-tidal breath CO (corrected for ambient CO) or ETCOc can serve as an index of hemolysis as well as of bilirubin production from any cause. Elevated levels of ETCOc have been correlated with blood carboxyhemoglobin levels and thus hemolysis. However, the detection of hemolysis can be a clinically challenging problem in newborns. Here, we describe the importance of determining ETCOc levels and their application in identifying infants at risk for developing hyperbilirubinemia associated with hemolysis and other causes of increased bilirubin production.

Age-dependent pattern of cerebellar susceptibility to bilirubin neurotoxicity in vivo in mice

Neonatal jaundice is caused by high levels of unconjugated bilirubin. It is usually a temporary condition caused by delayed induction of UGT1A1, which conjugates bilirubin in the liver. To reduce bilirubin levels, affected babies are exposed to phototherapy (PT), which converts toxic bilirubin into water-soluble photoisomers that are readily excreted out. However, in some cases uncontrolled hyperbilirubinemia leads to neurotoxicity. To study the mechanisms of bilirubin-induced neurological damage (BIND) in vivo, we generated a mouse model lacking the Ugt1a1 protein and, consequently, mutant mice developed jaundice as early as 36 hours after birth. The mutation was transferred into two genetic backgrounds (C57BL/6 and FVB/NJ). We exposed mutant mice to PT for different periods and analyzed the resulting phenotypes from the molecular, histological and behavioral points of view. Severity of BIND was associated with genetic background, with 50% survival of C57BL/6‑Ugt1^−/− mutant mice at postnatal day 5 (P5), and of FVB/NJ-Ugt1^−/− mice at P11. Life-long exposure to PT prevented cerebellar architecture alterations and rescued neuronal damage in FVB/NJ-Ugt1^−/− but not in C57BL/6-Ugt1^−/− mice. Survival of FVB/NJ-Ugt1^−/− mice was directly related to the extent of PT treatment. PT treatment of FVB/NJ-Ugt1^−/− mice from P0 to P8 did not prevent bilirubin-induced reduction in dendritic arborization and spine density of Purkinje cells. Moreover, PT treatment from P8 to P20 did not rescue BIND accumulated up to P8. However, PT treatment administered in the time-window P0–P15 was sufficient to obtain full rescue of cerebellar damage and motor impairment in FVB/NJ-Ugt1^−/− mice. The possibility to modulate the severity of the phenotype by PT makes FVB/NJ-Ugt1^−/− mice an excellent and versatile model to study bilirubin neurotoxicity, the role of modifier genes, alternative therapies and cerebellar development during high bilirubin conditions.

Subthalamic nucleus involvement in children: a neuroimaging pattern-recognition approach

A neuroimaging-based pattern-recognition approach has been shown to be very helpful in the diagnosis of a wide range of pediatric central nervous system diseases. Few disorders may selectively affect the subthalamic nucleus in children including Leigh syndrome, succinic semialdehyde dehydrogenase deficiency, kernicterus, chronic end-stage liver failure and near total hypoxic-ischemic injury in the full-term neonates. The consideration of the constellation of clinical history and findings as well as additional neuroimaging findings should allow planning the appropriate diagnostic tests to make the correct diagnosis in children with involvement of the subthalamic nucleus.

[Pathological jaundice of the newborn at Bonzola Mbuji-Mayi hospital, Democratic Republic of Congo]

L'ictère néonatal, bien qu'il soit souvent très banal, ne doit pas pour autant être négligé car il peut relever des étiologies variées et avoir des significations différentes au point de devenir pathologique. Au cours d'une étude rétro-prospective descriptive, les auteurs analysent les aspects épidemio-cliniques, thérapeutiques et évolutifs des ictères néonataux pathologiques à l'Unité des Urgences Néonatales de Bonzola à Mbuji-Mayi (RD Congo) sur une période de 5 ans. La fréquence est de 4,9% avec une incidence annuelle de 24 cas/an. La prédominance masculine est notée avec un sexe ratio de 1,1. Ces ictères sont précoces (31,1%) et tardif (17,5%). Les principales causes sont dans 81,6% des cas dominées par les infections (42,5%) et, incompatibilité fœto-maternelle (39,1%). La symptomatologie habituelle est notée: ictère franc et pâleur cutanéo-muqueuse (100%), urines jaunes foncées (62,5%), signes neurologiques (42,5%) et généraux (47,5%). Le traitement était à la fois étiologique (60%) et symptomatique ou d'appoint (40%) et a consisté dans l'association antibiotiques avec transfusion et/ou exsanguino-transfusion (24,2%), antibiothérapie seule (35,8%), inducteurs enzymatiques (35%) et photothérapie (5%). L’évolution a été bonne dans 82,3% des cas contre 9,3% des décès.

Bilirubin mediated oxidative stress involves antioxidant response activation via Nrf2 pathway

Unconjugated bilirubin (UCB) is responsible for neonatal jaundice and high level of free bilirubin (Bf) can lead to kernicterus. Previous studies suggest that oxidative stress is a critical component of UCB-induced neurotoxicity. The Nrf2 pathway is a powerful sensor for cellular redox state and is activated directly by oxidative stress and/or indirectly by stress response protein kinases. Activated Nrf2 translocates to nucleus, binds to Antioxidant Response Element (ARE), and enhances the up-regulation of cytoprotective genes that mediate cell survival. The aim of the present study was to investigate the role of Nrf2 pathway in cell response to bilirubin mediated oxidative stress in the neuroblastoma SH-SY5Y cell line. Cells exposed to a toxic concentration of UCB (140 nM Bf) showed an increased intracellular ROS levels and enhanced nuclear accumulation of Nrf2 protein. UCB stimulated transcriptional induction of ARE-GFP reporter gene and induced mRNA expression of multiple antioxidant response genes as: xCT, Gly1, γGCL-m, γGCL-c, HO-1, NQO1, FTH, ME1, and ATF3. Nrf2 siRNA decreased UCB induced mRNA expression of HO1 (75%), NQO1 (54%), and FTH (40%). The Nrf2-related HO-1 induction was reduced to 60% in cells pre-treated with antioxidant (NAC) or specific signaling pathway inhibitors for PKC, P38α and MEK1/2 (80, 40 and 25%, respectively). In conclusion, we demonstrated that SH-SY5Y cells undergo an adaptive response against UCB-mediated oxidative stress by activation of multiple antioxidant response, in part through Nrf2 pathway.

MRI Findings in a Dog with Kernicterus

A severe increase in total bilirubin coincided with a decline in neurologic status to comatose in a 9 yr old spayed female mixed-breed dog being treated for immune-mediated hemolytic anemia. MRI of the brain was performed to investigate potential causes for the neurologic signs. MRI revealed bilaterally symmetrical hyperintensities within the caudate nuclei, globus pallidus, thalamus, deep cerebellar nuclei, and cortical gray matter on T2-weighted and fluid-attenuated inversion recovery (FLAIR) sequences, which coincided with areas of bilirubin deposition and neuronal necrosis (kernicterus) identified on necropsy examination. This is the second case report of an adult dog exhibiting kernicterus, and the first report to document MRI findings associated with that condition. Kernicterus is an uncommonly reported complication of hyperbilirubinemia in dogs, but is potentially underreported due to difficulties in recognizing subtle lesions and distinguishing kernicterus from other potential causes of neurologic abnormalities with readily available antemortem tests. MRI may be helpful in supporting the diagnosis of kernicterus.

Heme oxygenase-1 as a target for TGF-β in kidney disease

Transforming growth factor-β (TGF-β) is a multifunctional regulatory cytokine that is implicated in a variety of kidney diseases, including diabetic nephropathy and chronic transplant rejection, where it promotes stimulation of the extracellular matrix deposition, cell proliferation, and migration. TGF-β exerts its biological functions largely via its downstream complex signaling molecules, Smad proteins. Paradoxically, TGF-β also is essential for normal homeostasis and suppression of inflammation through mechanisms that are yet to be fully elucidated. One feasible mechanism by which TGF-β may exert its beneficial properties is through induction of heme oxygenase-1 (HO-1). Induction of this redox-sensitive enzyme is known to be cytoprotective through its potent antioxidant, anti-inflammatory, and anti-apoptotic properties in different conditions including several kidney diseases. In this overview, recent advances in our understanding of the role of TGF-β in kidney disease, its molecular regulation of HO-1 expression, and the potential role of HO-1 induction as a therapeutic modality in TGF-β-mediated kidney diseases are highlighted.

Vestibular evoked myogenic potentials in term newborn infants with severe hyperbilirubinemia

BACKGROUND

The aim of this study was to determine the effects of severe hyperbilirubinemia on vestibular evoked myogenic potentials (VEMP).

METHODS

A prospective study was designed. Seventeen term infants who suffered from severe hyperbilirubinemia in the first 5 postnatal days of age were included in the study group. The control group consisted of 17 healthy term infants. Audiological evaluation was performed, including tympanometry and transient evoked otoacoustic emissions, and VEMP tests.

RESULTS

All newborns passed audiological evaluation. Biphasic waveforms of VEMP were obtained in all of the 34 infants who had been tested. Both latencies of p13 and n23 were significantly delayed in the severe hyperbilirubinemia group (P < 0.05).

CONCLUSION

This pilot is the first study to show that severe hyperbilirubinemia causes delay in VEMP latencies. We suggest that severe hyperbilirubinemia might affect the vestibular nuclei or the integrity of the inferior vestibular nerve and vestibulospinal tract. Further studies need to explain the relation between hyperbilirubinemia and the vestibular system.

Disruption of the serotonergic system after neonatal hypoxia-ischemia in a rodent model

Identifying which specific neuronal phenotypes are vulnerable to neonatal hypoxia-ischemia, where in the brain they are damaged, and the mechanisms that produce neuronal losses are critical to determine the anatomical substrates responsible for neurological impairments in hypoxic-ischemic brain-injured neonates. Here we describe our current work investigating how the serotonergic network in the brain is disrupted in a rodent model of preterm hypoxia-ischemia. One week after postnatal day 3 hypoxia-ischemia, losses of serotonergic raphé neurons, reductions in serotonin levels in the brain, and reduced serotonin transporter expression are evident. These changes can be prevented using two anti-inflammatory interventions; the postinsult administration of minocycline or ibuprofen. However, each drug has its own limitations and benefits for use in neonates to stem damage to the serotonergic network after hypoxia-ischemia. By understanding the fundamental mechanisms underpinning hypoxia-ischemia-induced serotonergic damage we will hopefully move closer to developing a successful clinical intervention to treat neonatal brain injury.

Rescue of bilirubin-induced neonatal lethality in a mouse model of Crigler-Najjar syndrome type I by AAV9-mediated gene transfer

Crigler-Najjar type I (CNI) syndrome is a recessively inherited disorder characterized by severe unconjugated hyperbilirubinemia caused by uridine diphosphoglucuronosyltransferase 1A1 (UGT1A1) deficiency. The disease is lethal due to bilirubin-induced neurological damage unless phototherapy is applied from birth. However, treatment becomes less effective during growth, and liver transplantation is required. To investigate the pathophysiology of the disease and therapeutic approaches in mice, we generated a mouse model by introducing a premature stop codon in the UGT1a1 gene, which results in an inactive enzyme. Homozygous mutant mice developed severe jaundice soon after birth and died within 11 d, showing significant cerebellar alterations. To rescue neonatal lethality, newborns were injected with a single dose of adeno-associated viral vector 9 (AAV9) expressing the human UGT1A1. Gene therapy treatment completely rescued all AAV-treated mutant mice, accompanied by lower plasma bilirubin levels and normal brain histology and motor coordination. Our mouse model of CNI reproduces genetic and phenotypic features of the human disease. We have shown, for the first time, the full recovery of the lethal effects of neonatal hyperbilirubinemia. We believe that, besides gene-addition-based therapies, our mice could represent a very useful model to develop and test novel technologies based on gene correction by homologous recombination.

The need for technologies to prevent bilirubin-induced neurologic dysfunction syndrome

Dramatic improvements in the overall socioeconomic conditions have yet to impact the unacceptably high maternal (approximately 1500 maternal deaths daily, worldwide) and neonatal morbidity and mortality (more than 10,000 deaths per daily 200,000 live-births, worldwide) in the developing nations. Thus, nations with emerging markets have unique health-societal needs. All infants require a safer transition from a birthing facility to home during the first week after birth and providing for a nurturing environment to prevent neonatal illnesses is integral to "good clinical practice." The unmonitored occurrence of severe hyperbilirubinemia and kernicterus are emblematic of a fractured maternal child healthcare system. The "know-do" gaps that span private versus public health care systems in the emerging markets have led us to conclude that building an interdisciplinary leadership approach to provide innovative strategies and affordable technologies will help bridge and access existing social barriers in the micro- and macro-health environments. Thus, unfettered access, global benchmarks, and culturally relevant strategies are dependent on evidence-based affordable technologies to successfully transform societal health care practices. Implementation of jaundice-related technologies should serve as a template for other affordable newborn health products.

The clinical syndrome of bilirubin-induced neurologic dysfunction

We believe that the syndrome of bilirubin-induced neurologic dysfunction [BIND] represents a spectrum of neurologic manifestations among vulnerable infants who have experienced an exposure to bilirubin of lesser degree than generally described in previous publications. Clinical neuro-motor manifestations extend to a range of subtle processing disorders with objective disturbances of visual-motor, auditory, speech, cognition, and language among infants with a previous history of moderate-to-severe hyperbilirubinemia of varied duration. Confounding effects include prematurity, hemolysis, perinatal-neonatal complications, altered bilirubin-albumin binding, severity and duration of bilirubin exposure, and the individual vulnerability of the infant related to genetic, family, social, and educational predilection, regardless of the cause of neonatal jaundice. Tools to better assess BIND specific domains of multisensory processing disorders, identified by pyschometric, audiologic, speech, language and visual-motor, and neuromotor examination would allow for prospective surveillance of infants at risk for the syndrome.

Evaluation of oxidant and antioxidant status in infants with hyperbilirubinemia and kernicterus

Objective: The objective of the present study was to determine oxidant and antioxidant status in infants with hyperbilirubinemia and/or kernicterus and to find whether there is a relationship between bilirubin level and oxidant/antioxidant status. Patients: The study includes 69 full-term newborns (neonates with hyperbilirubinemia needing phototherapy [Group 1, n = 36] and neonates with kernicterus [Group 2, n = 33]) and 25 age-matched healthy newborn. Results: Plasma total antioxidant capacity (TAC) and serum total oxidant status (TOS) were significantly higher in Groups 1 and 2 than the control group. There was a significant difference between Group 1 and control cases for malondialdehyde (MDA; p < 0.001). Total free sulfhydryl group (TTHI) values were significantly elevated in Group 1 compared to Group 2 and control cases. Correlation analysis showed that the correlation between total bilirubin (TB) and TAC, TOS, MDA and oxidative stress index may be expressed by a quadratic curve. After phototherapy, a statistically significant increase in nitrite level was observed. Conclusion: We demonstrated that the relationship between serum TB and antioxidants and oxidative stress could be expressed by a quadratic correlation curve.

Modulation of Mrp1 (ABCc1) and Pgp (ABCb1) by bilirubin at the blood-CSF and blood-brain barriers in the Gunn rat

Accumulation of unconjugated bilirubin (UCB) in the brain causes bilirubin encephalopathy. Pgp (ABCb1) and Mrp1 (ABCc1), highly expressed in the blood-brain barrier (BBB) and blood-cerebrospinal fluid barrier (BCSFB) respectively, may modulate the accumulation of UCB in brain. We examined the effect of prolonged exposure to elevated concentrations of UCB on expression of the two transporters in homozygous, jaundiced (jj) Gunn rats compared to heterozygous, not jaundiced (Jj) littermates at different developmental stages (2, 9, 17 and 60 days after birth). BBB Pgp protein expression was low in both jj and Jj pups at 9 days (about 16-27% of adult values), despite the up-regulation in jj animals (2 and 1.3 fold higher than age matched Jj animals at P9 and P17-P60, respectively); Mrp1 protein expression was barely detectable. Conversely, at the BCSFB Mrp1 protein expression was rather high (60-70% of the adult values) in both jj and Jj at P2, but was markedly (50%) down-regulated in jj pups starting at P9, particularly in the 4(th) ventricle choroid plexuses: Pgp was almost undetectable. The Mrp1 protein down regulation was accompanied by a modest up-regulation of mRNA, suggesting a translational rather than a transcriptional inhibition. In vitro exposure of choroid plexus epithelial cells obtained from normal rats to UCB, also resulted in a down-regulation of Mrp1 protein. These data suggest that down-regulation of Mrp1 protein at the BSCFB, resulting from a direct effect of UCB on epithelial cells, may impact the Mrp1-mediated neuroprotective functions of the blood-cerebrospinal fluid barrier and actually potentiate UCB neurotoxicity.

Acute hyperbilirubinaemia induces presynaptic neurodegeneration at a central glutamatergic synapse

There is a well-established link between hyperbilirubinaemia and hearing loss in paediatrics, but the cellular mechanisms have not been elucidated. Here we used the Gunn rat model of hyperbilirubinaemia to investigate bilirubin-induced hearing loss. In vivo auditory brainstem responses revealed that Gunn rats have severe auditory deficits within 18 h of exposure to high bilirubin levels. Using an in vitro preparation of the auditory brainstem from these rats, extracellular multi-electrode array recording from the medial nucleus of the trapezoid body (MNTB) showed longer latency and decreased amplitude of evoked field potentials following bilirubin exposure, suggestive of transmission failure at this synaptic relay. Whole-cell patch-clamp recordings confirmed that the electrophysiological properties of the postsynaptic MNTB neurons were unaffected by bilirubin, with no change in action potential waveforms or current-voltage relationships. However, stimulation of the trapezoid body was unable to elicit large calyceal EPSCs in MNTB neurons of hyperbilirubinaemic rats, indicative of damage at a presynaptic site. Multi-photon imaging of anterograde-labelled calyceal projections revealed axonal staining and presynaptic profiles around MNTB principal neuron somata. Following induction of hyperbilirubinaemia the giant synapses were largely destroyed. Electron microscopy confirmed loss of presynaptic calyceal terminals and supported the electrophysiological evidence for healthy postsynaptic neurons. MNTB neurons express high levels of neuronal nitric oxide synthase (nNOS). Nitric oxide has been implicated in mechanisms of bilirubin toxicity elsewhere in the brain, and antagonism of nNOS by 7-nitroindazole protected hearing during bilirubin exposure. We conclude that bilirubin-induced deafness is caused by degeneration of excitatory synaptic terminals in the auditory brainstem.

Universal bilirubin screening for severe neonatal hyperbilirubinemia

To reduce the incidence of severe neonatal hyperbilirubinemia affecting newborns with jaundice in the United States and to prevent kernicterus, there is a need to implement proven prevention strategies for severe neonatal hyperbilirubinemia as recommended in the 2004 American Academy of Pediatrics Guidelines for newborns >35 weeks gestational age. The purpose of universal predischarge bilirubin screening is to identify infants with bilirubin levels >75th percentile for age in hours and track those with rapid rates of bilirubin rise (>0.2 mg per 100 ml per h). Early identification has been reported to predict severe hyperbilirubinemia and allow for evidence-based targeted interventions. A systems approach is likely to reduce the preventable causes of acute bilirubin encephalopathy. To do so, highest priority should be given to (i) designating extreme hyperbilirubinemia (total serum bilirubin >427 μmol l(-1) or >25 mg per 100 ml) as a reportable condition by laboratories and health-care providers through public health mandates; (ii) implementation of Joint Commission's Sentinel Report for kernicterus; (iii) nursing outreach to communities for education of prospective parents; (iv) development of clinical pathways to monitor, evaluate and track infants with extreme hyperbilirubinemia; and (v) societal awareness. These efforts should be monitored by a state and national surveillance system in order to critically improve the timeliness and completeness of notifications and to allow evaluation and interventions at the policy and individual family level.

The significance of measurement of serum unbound bilirubin concentrations in high-risk infants

BACKGROUND

In the management of neonatal hyperbilirubinemia, total bilirubin (TB) concentration is not specific enough to predict the brain damage caused by bilirubin toxicity. Unbound bilirubin (UB) easily passes the blood-brain barrier and causes neurotoxicity. We aimed to evaluate whether serum UB concentration would be a useful predictor of bilirubin encephalopathy in high-risk infants.

METHODS

We measured the serum TB and UB concentrations of 388 newborn infants treated with phototherapy or exchange transfusion for their hyperbilirubinemia at Takatsuki General Hospital between January 2002 and October 2003. Peak serum TB and UB levels and UB/TB ratios were studied on each birthweight group: below 1500 g (very low birthweight), 1500 g-2499 g (low birthweight), above 2500 g (normal birthweight); and several clinical factors influencing hyperbilirubinemia were also studied.

RESULTS

Peak serum TB and UB levels increased with increasing birthweight, while UB/TB ratios decreased. The very low birthweight group showed higher UB levels and UB/TB ratios despite lower TB levels in intraventricular hemorrhage or severe infection compared to those in the others. The low birthweight and normal birthweight groups showed higher TB and UB levels in cases of hemolytic disease of the newborn compared to non-hemolytic disease of the newborn cases. Eight of 44 cases showed high UB levels accompanied by abnormal auditory brainstem responses, one of whom subsequently developed ataxic cerebral palsy with hearing loss, whereas the other seven showed transient abnormalities of auditory brainstem responses by the treatment of exchange transfusion or phototherapy.

CONCLUSION

The UB measurement was considered to be significant for the assessment of the risk of bilirubin neurotoxicity and the appropriate intervention for hyperbilirubinemia in high-risk infants.

Screening for severe neonatal hyperbilirubinemia

Screening for severe neonatal hyperbilirubinemia is integral to newborn care. Predischarge risk assessment relies on documentation of visual jaundice: age at onset and progression; identification of clinical risk such as late prematurity and bruising; with determination of total bilirubin (blood or transcutaneous assay) adjusted for age in hours. Along with promotion of breastfeeding, coordination between birthing hospital and medically supervised outpatient follow-up, a systems approach allows for a safer and effective means to prevent adverse effects of extreme hyperbilirubinemia.

Minocycline: a neuroprotective agent for hypoxic-ischemic brain injury in the neonate?

Minocycline is a second-generation tetracycline and a potential neuroprotective intervention following brain injury. However, despite the recognized beneficial effects of minocycline in a multitude of adult disease states, the clinical application of minocycline in neonates is contentious. Tetracyclines, as a class, are not usually administered to neonates, but there is compelling evidence that minocycline reduces brain injury after neonatal hypoxic-ischemic brain injury. This Review focuses on the evidence for minocycline use in neonates by considering aspects of pharmacology, drug regimens, functional outcomes, and mechanisms of action.