Developmental influence of unconjugated hyperbilirubinemia and neurobehavioral disorders

The relationship between preoperative serum indirect bilirubin and postoperative delirium in geriatric patients undergoing joint replacement

BACKGROUND

Postoperative delirium (POD) is one of the most common complications in geriatric patients following surgery. Physiological concentration of bilirubin possesses anti-inflammatory, antioxidant and neuroprotective effects, which are important protective mechanisms against POD. This study aimed to explore the relationship between preoperative serum bilirubin and POD in geriatric patients undergoing joint replacement.

METHODS

Geriatric patients who underwent hip or knee joint replacement surgery under intrathecal anesthesia were included. These patients had American Society of Anesthesiologists (ASA) grades I to III. The patients with a history of psychiatric or neurological disorders, infectious diseases or sepsis, hemolytic anemia, liver diseases, performed general anesthesia or intrathecal anesthesia combined with general anesthesia, or insufficient surgical information were excluded. Patients' age, gender, weight, height, ASA classification, liver function and bilirubin within one week before surgery, preoperative Mini-Mental State Examination (MMSE) scores, surgical type, dosage of medications, intraoperative bleeding volume, postoperative average numeric rating scale (NRS) pain scores, the occurrence of POD and Delirium Rating Scale-Revised-98 (DRS-R-98) scores for POD were collected.

RESULTS

A total of 269 patients were eligible for inclusion in the study, with 23.05% (62/207) exhibiting POD. Patients with POD exhibited higher age and ASA classification, and had lower weight, serum total serum bilirubin (TBIL) and indirect bilirubin (IBIL) within one week before surgery, and preoperative MMSE scores (all p < 0.05). Univariate logistic regression analysis showed that the above variables were correlated with the occurrence of POD (all p < 0.05). Multivariate logistic regression analysis revealed that age was a risk factor (p < 0.001, OR = 1.14, 95% CI [1.07-1.21]), while weight (p = 0.041, OR = 0.96, 95% CI [0.92-0.99]), IBIL levels within one week before surgery (p = 0.012, OR = 0.65, 95% CI [0.47-0.91]) and preoperative MMSE scores (p < 0.001, OR = 0.84, 95% CI [0.78-0.91]) served as protective factors against the occurrence of POD. The serum IBIL concentration within one week before surgery was performed receiver operating characteristic (ROC) curve analysis. The estimated cutoff value for predicting the occurrence of POD was 6.65 μmol/L, and area under the curve (AUC) was 0.63. Patients with preoperative serum IBIL concentration below 6.65 μmol/L had a higher incidence of POD.

CONCLUSION

Patients with lower preoperative serum IBIL levels exhibited a higher incidence of POD in geriatric patients undergoing joint replacement. Low serum IBIL was a risk factor and a predictor for the occurrence of POD.

Bilirubin Triggers Calcium Elevations and Dysregulates Giant Depolarizing Potentials During Rat Hippocampus Maturation

Neonatal hyperbilirubinemia may result in long-lasting motor, auditory and learning impairments. The mechanisms responsible for the localization of unconjugated bilirubin (UCB) to specific brain areas as well as those involved in potentially permanent central nervous system (CNS) dysfunctions are far from being clear. One area of investigation includes exploring how hyperbilirubinemia determines neuronal alterations predisposing to neurodevelopmental disorders. We focused on the hippocampus and pyramidal cell dysregulation of calcium homeostasis and synaptic activity, with a particular focus on early forms of correlated network activity, i.e., giant depolarizing potentials (GDPs), crucially involved in shaping mature synaptic networks. We performed live calcium imaging and patch clamp recordings from acute hippocampal slices isolated from wild-type rats exposed to exogenous high bilirubin concentration. We then explored the impact of endogenous bilirubin accumulation in hippocampal slices isolated from a genetic model of hyperbilirubinemia, i.e., Gunn rats. Our data show in both models an age-dependent dysregulation of calcium dynamics accompanied by severe alterations in GDPs, which were strongly reduced in hippocampal slices of hyperbilirubinemic rats, where the expression of GABAergic neurotransmission markers was also altered. We propose that hyperbilirubinemia damages neurons and affects the refinement of GABAergic synaptic circuitry during a critical period of hippocampal development.

Effect of chest shielding during phototherapy for hyperbilirubinemia on symptomatic patent ductus arteriosus - a double-blind randomized placebo-controlled trial

BACKGROUND

Meta-analysis of randomized trials suggests that phototherapy is associated with patent ductus arteriosus (PDA). We hypothesized that chest shielding during phototherapy would decrease the incidence of symptomatic PDA (sPDA) compared to sham shielding.

METHODS

A single center, double-blind, randomized, placebo-controlled trial was performed to evaluate the effect of chest shielding during phototherapy on sPDA in infants ≤ 29 weeks gestational age (GA) or with birth weight (BW) ≤ 1000 g. Infants were randomized to either chest shield (with aluminum foil, intervention group) or sham shield (without aluminum foil, control group) during phototherapy. The primary outcome was sPDA during the period 24 h after phototherapy initiation until 3 days after phototherapy cessation.

RESULTS

160 infants were randomized with 10 infants withdrawn from each group due to shield placement after phototherapy initiation. Of 140 infants analyzed, the mean GA and BW was 26.6 weeks and 872 g, respectively. There was no difference in the incidence of sPDA between the intervention (n = 70) and control group (n = 70) (10% vs 11%, respectively, adjusted odds ratio 0.78, 95% CI:0.33-1.82; p = 0.57).

CONCLUSIONS

Chest shielding during phototherapy had no effect on sPDA in infants ≤ 29 weeks GA or with BW ≤ 1000 g.

TRIAL REGISTRATION

http://clinicaltrials.gov , Identifier: NCT02552927.

IMPACT

Meta-analysis of randomized clinical trials suggests that chest shielding during phototherapy used for hyperbilirubinemia may decrease the incidence of patent ductus arteriosus. The effect of chest shielding during phototherapy on symptomatic patent ductus arteriosus has not been evaluated in a double-blind randomized trial. In this double-blind, randomized, placebo-controlled trial, chest shielding during phototherapy was not associated with a decreased incidence of symptomatic patent ductus arteriosus in premature infants.

Severe neonatal hyperbilirubinaemia in European and Indian subcontinent descendent newborns: a retrospective cohort study

Neonatal hyperbilirubinaemia is more common in Asian-descendent populations, but differences in disease severity are poorly reported. Our study aimed to compare neonatal hyperbilirubinaemia severity between European and Indian subcontinent descendent newborns. We conducted a single-centre retrospective cohort study including newborns admitted with unconjugated hyperbilirubinaemia (January 2016 to December 2021). Patients were followed during admission, comparing those with European ancestry (control group) and Indian subcontinent ancestry (India, Pakistan, Bangladesh and Nepal) (study group). The primary outcome was severe hyperbilirubinemia (TSB > 25 mg/dL, phototherapy > 6 h or need for exchange transfusion [ET]), and the secondary was TSB levels. Adjusted analysis for potential confounding factors was performed using binary logistic regression models. Of 110 newborns included, 27 (24.5%) had Indian subcontinent ancestry. Occurrence of TSB > 25 mg/dL was significantly higher in the study group (22.2% vs. 4.8%, p = 0.006), while no differences were noted in exposure to phototherapy > 6 h and ET therapy. Logistic regression models for confounding factors adjustment showed Indian subcontinent ancestry as an independent risk factor for TSB > 25 mg/dL (OR 7.49, CI 95% [1.23-45.50]). The study group revealed also higher absolute values of TSB both at admission (22.0 mg/dL vs. 19.6 mg/dL, p = 0.013) and at discharge (13.6 mg/dL vs. 11.4 mg/dL, p = 0.005). Conclusion: Our findings suggest that newborns with Indian subcontinent ancestry might show a higher risk for the development of severe hyperbilirubinemia compared to European ancestry newborns. Implementing earlier treatment thresholds in this subset of patients may help prevent severe hyperbilirubinemia.  What is Known: • Indian subcontinent descendent populations have high incidence of neonatal hyperbilirubinaemia but data regarding its severity are scarce. What is New: • This article shows that, compared to European descendent newborns, Indian subcontinent descendent newborns might be at higher risk for severe hyperbilirubinaemia.

Effect of intravenous immunoglobulin on the management of Rh- and ABO-mediated hemolytic disease of the newborn

BACKGROUND

Regarding the close association between neonatal hyperbilirubinemia and occurrence of pathological jaundice as a cause of neurotoxicity and kernicterus, the present study aimed to evaluate the use of intravenous immunoglobulin (IVIG) in neonates with hyperbilirubinemia.

METHODS

A retrospective case-control study of blood group O mothers and their ABO and Rh newborns was conducted. Medical records that included total serum bilirubin levels of 79 patients with hemolytic disease of the newborn (HDN) from between 2017 and 2020 were reviewed. Neonates who were eligible to receive immunoglobulin based on the American Academy of Pediatrics (AAP) guidelines were classified as cases and the rest were included as the Control Group.

RESULTS

The mean total bilirubin in relation to hemoglobin levels in IVIG-treated neonates was significantly lower than in non-IVIG-treated neonates (13.98 ± 4.23 mg/dL versus 16.61 ± 2.68 mg/dL; p-value = 0.002). Although females had longer hospitalizations in both IVIG-treated (3.81 ± 1.28 versus 3.54 ± 1.30 days; p-value = 0.509) and non-IVIG-treated (3.43 ± 0.811 versus 3.19 ± 0.75 days; p-value = 0.361) groups compared to males, this difference was not significant between the groups. Although four neonates with ABO incompatibility required packed red blood cells, all infants were managed medically and no deaths occurred during the course of treatment. Moreover, no exchange transfusion or adverse effects of IVIG were observed.

CONCLUSION

The results from the present study revealed that IVIG administration is a useful procedure for the management of bilirubin encephalopathy with greater opportunity to reduce exchange transfusion requirements for neonatal hyperbilirubinemia.

Dynamic whole-transcriptome landscape of acute bilirubin encephalopathy in newborns

Hyperbilirubinemia in newborns may progress to acute bilirubin encephalopathy (ABE), posing short- and long-term health risks. Despite extensive research identifying numerous mRNAs, lncRNAs, circRNAs, and miRNAs associated with brain injury, their roles in neonatal bilirubin-induced brain injury remain elusive. This study employed whole-transcriptome sequencing to ascertain the differentially expressed (DE) RNA profiles in a newborn ABE rat model, followed by bioinformatic analysis. A time-series competing endogenous RNA (ceRNA) regulatory network was established, and the expression trends of 9 arbitrarily chosen RNAs were verified through quantitative real-time polymerase chain reaction(qRT-PCR). In comparison with the control group, we identified 595, 888, and 1448 DE mRNAs; 22, 37, and 37 DE miRNAs; 1945, 1869, and 1997 DE lncRNAs; and 31, 28, and 36 DE circRNAs at 6 h, 12 h, and 24 h, respectively. Predominantly, these DERNAs contribute to biological functions and pathways associated with inflammation, immunity, metabolism, cell death, and neurodevelopmental regulation. Moreover, we constructed ceRNA networks of DE lncRNA/circRNA-DE miRNA-DE mRNA based on time series. The qRT-PCR expression trends for the selected 9 RNAs were generally similar to the RNA-seq outcomes. This investigation uniquely delineated the temporal expression patterns of mRNA and non-coding RNA in ABE, establishing ceRNA networks and identifying potential molecular mechanisms underlying bilirubin-induced hippocampal damage. Nonetheless, further studies are warranted to corroborate these findings in humans.

Bilirubinemia and retinopathy of prematurity in infants ≤ 29 weeks' gestational age

BACKGROUND

Bilirubin is a known antioxidant. We hypothesized that the degree of bilirubinemia is inversely associated with oxidative stress-mediated retinopathy of prematurity (ROP).

METHODS

A prospective study was performed to determine if bilirubinemia is associated with ROP in infants ≤ 29 wks' gestational age and birth weights ≤ 1000 g. Total serum bilirubin (TSB) levels were measured at least twice daily during the first week and at least daily during the second week to determine peak and mean TSB levels. The outcomes were the incidence and severity of ROP.

RESULTS

Of 193 infants studied, 110 developed ROP: 53 had mild (stage 1 in zone 2 or 3); 31 had moderate (stage 2 in zone 2 or 3); and 26 had severe ROP ( ≥ stage 3 in any zone or any stage in zone 1). Mean TSB levels were associated with the severity (adjusted odds ratio [AOR] 0.68, 95% confidence interval [CI]:0.47-0.98, p = 0.04), but not with the incidence of ROP (AOR 0.81, 95% CI:0.52-1.27, p = 0.3). Peak TSB levels were also associated with the severity (AOR 0.71, 95% CI:0.52-0.96, p = 0.02), but not with the incidence of ROP (AOR 0.71, 95% CI:0.48-1.01, p = 0.07).

CONCLUSIONS

Bilirubinemia may be protective against severity of ROP.

IMPACT

Retinopathy of prematurity (ROP) is a disease mediated by oxidative stress. Increasing antioxidant status may decrease the incidence and severity of ROP. Bilirubin is a known antioxidant; however, findings from observational studies evaluating the role of bilirubinemia against the incidence and/or severity of ROP in premature infants are conflicting. Our findings from this prospective study suggests that bilirubinemia may be protective against the severity of ROP.

Neonatal hyperbilirubinemia and repercussions on neurodevelopment: A systematic review

BACKGROUND

Accumulation of bilirubin above normal levels is considered a neurological risk factor for both premature and full-term newborns. This systematic review aimed to determine the effect of neonatal hyperbilirubinemia on neurodevelopment in preterm and full-term newborns.

METHODS

PubMed, EMBASE, Cochrane Library, CINAHL, PsycINFO, Scopus and Lilacs databases were searched for articles published until 1 June 2022. The quality of cohort and case-control studies was assessed with the Newcastle-Ottawa Scale, and the MINCir scale was used to evaluate the methodological quality of therapy studies or the therapeutic procedures. Premature neonates without neurological conditions and those born at term with hyperbilirubinemia as the sole risk factor were included. Studies reporting one or more neurodevelopmental outcomes were included with an inter-group comparison of a hyperbilirubinemia group versus a non-hyperbilirubinemia or non-pathological hyperbilirubinemia group. The main outcomes were auditory function, visual function, cognitive function, motor function, behavior, global development and neurological risk.

RESULTS

The search identified 951 studies, 19 of which (n = 2210 newborns) were finally included. Fifteen of the cohort and case-control studies presented low risk of bias, and six studies showed high methodological quality. Within the preterm population, hyperbilirubinemia as the sole risk factor was not shown to affect neurodevelopment. Auditory, neurological and motor development alterations were found in the population of full-term newborns with hyperbilirubinemia, which were more evident during the first year of life.

CONCLUSIONS

Elevated bilirubin levels may be a trigger for the onset of neurodevelopmental disorders in full-term infants during the first year of life. More studies are warranted in the preterm population with hyperbilirubinemia to draw conclusions about its impact on their neurodevelopment.

An investigation of motor development and sensory processing skills in infants with a history of hyperbilirubinemia

BACKGROUND

Hyperbilirubinemia is a clinical picture frequently occurring in the neonatal period and may negatively affect the development of infants.

AIMS

To evaluate term infants with hyperbilirubinemia in terms of both motor development and sensory processing skills and to compare them with their healthy peers without hyperbilirubinemia.

STUDY DESIGN

A cross-sectional study.

SUBJECTS

Children born at term, aged 10-18 months, with and without a history of hyperbilirubinemia were included in the study.

OUTCOME MEASURES

After demographic information was recorded, motor development was evaluated with the Peabody Motor Development Scale-2 and sensory processing skills were evaluated with the Test of Sensory Function in Infant.

RESULTS

A total of 42 children (mean ± SD age of the children 13.07 ± 1.47 months, 22 with hyperbilirubinemia and 20 without hyperbilirubinemia) were included in the study. A statistically significant difference was found in the gross motor (p = 0.02), fine motor (p = 0.03), and total motor (p = 0.017) development scores of the Peabody Motor Development Scale-2 and in the adaptive motor functions (p = 0.004), visual tactile integration (p < 0.001), and total scores (p = 0.004) of The Test of Sensory Function in Infant in favor of the control group.

CONCLUSIONS

The motor and sensory processing skills of children born at term with hyperbilirubinemia may be negatively affected. Infants with hyperbilirubinemia should be evaluated from the early period not only in terms of motor but also sensory processing skills and should be supported with appropriate intervention programs.

Bilirubin and Redox Stress in Age-Related Brain Diseases

Cellular redox status has a crucial role in brain physiology, as well as in pathologic conditions. Physiologic senescence, by dysregulating cellular redox homeostasis and decreasing antioxidant defenses, enhances the central nervous system's susceptibility to diseases. The reduction of free radical accumulation through lifestyle changes, and the supplementation of antioxidants as a prophylactic and therapeutic approach to increase brain health, are strongly suggested. Bilirubin is a powerful endogenous antioxidant, with more and more recognized roles as a biomarker of disease resistance, a predictor of all-cause mortality, and a molecule that may promote health in adults. The alteration of the expression and activity of the enzymes involved in bilirubin production, as well as an altered blood bilirubin level, are often reported in neurologic conditions and neurodegenerative diseases (together denoted NCDs) in aging. These changes may predict or contribute both positively and negatively to the diseases. Understanding the role of bilirubin in the onset and progression of NCDs will be functional to consider the benefits vs. the drawbacks and to hypothesize the best strategies for its manipulation for therapeutic purposes.

Inflammation, Dopaminergic Brain and Bilirubin

Dopamine is a well-known neurotransmitter due to its involvement in Parkinson's disease (PD). Dopamine is not only involved in PD but also controls multiple mental and physical activities, such as the pleasure of food, friends and loved ones, music, art, mood, cognition, motivation, fear, affective disorders, addiction, attention deficit disorder, depression, and schizophrenia. Dopaminergic neurons (DOPAn) are susceptible to stressors, and inflammation is a recognized risk for neuronal malfunctioning and cell death in major neurodegenerative diseases. Less is known for non-neurodegenerative conditions. Among the endogenous defenses, bilirubin, a heme metabolite, has been shown to possess important anti-inflammatory activity and, most importantly, to prevent DOPAn demise in an ex vivo model of PD by acting on the tumor necrosis factor-alpha (TNFα). This review summarizes the evidence linking DOPAn, inflammation (when possible, specifically TNFα), and bilirubin as an anti-inflammatory in order to understand what is known, the gaps that need filling, and the hypotheses of anti-inflammatory strategies to preserve dopamine homeostasis with bilirubin included.

Bilirubin-Induced Transcriptomic Imprinting in Neonatal Hyperbilirubinemia

Recent findings indicated aberrant epigenetic control of the central nervous system (CNS) development in hyperbilirubinemic Gunn rats as an additional cause of cerebellar hypoplasia, the landmark of bilirubin neurotoxicity in rodents. Because the symptoms in severely hyperbilirubinemic human neonates suggest other regions as privileged targets of bilirubin neurotoxicity, we expanded the study of the potential impact of bilirubin on the control of postnatal brain development to regions correlating with human symptoms. Histology, transcriptomic, gene correlation, and behavioral studies were performed. The histology revealed widespread perturbation 9 days after birth, restoring in adulthood. At the genetic level, regional differences were noticed. Bilirubin affected synaptogenesis, repair, differentiation, energy, extracellular matrix development, etc., with transient alterations in the hippocampus (memory, learning, and cognition) and inferior colliculi (auditory functions) but permanent changes in the parietal cortex. Behavioral tests confirmed the presence of a permanent motor disability. The data correlate well both with the clinic description of neonatal bilirubin-induced neurotoxicity, as well as with the neurologic syndromes reported in adults that suffered neonatal hyperbilirubinemia. The results pave the way for better deciphering the neurotoxic features of bilirubin and evaluating deeply the efficacy of new therapeutic approaches against the acute and long-lasting sequels of bilirubin neurotoxicity.

A Novel Drug with Potential to Treat Hyperbilirubinemia and Prevent Liver Damage Induced by Hyperbilirubinemia: Carbon Dots Derived from Platycodon grandiflorum

Platycodon grandiflorum (PG) is a traditional Chinese medicine with a long history, but its active compounds have not been reported. In this study, novel carbon dots (CDs), PG-based CDs (PGC-CDs), were discovered and prepared from PG via calcinations and characterized by transmission electron microscopy; high-resolution transmission electron microscopy; X-ray diffraction, fluorescence, ultraviolet-visible, and Fourier-transform infrared spectrometers; X-ray photoelectron spectroscopy; and high-performance liquid chromatography. In addition, the safety and antioxidant activity of PGC-CDs was evaluated by RAW264.7 cells and LO2 cells. The therapeutic effects of PGC-CDs on hyperbilirubinemia and liver protection were evaluated in a bilirubin-induced hyperbilirubinemia mice model. The experiment confirmed that the diameter range of PGC-CDs was from 1.2 to 3.6 nm. PGC-CDs had no toxicity to RAW264.7 cells and LO2 cells at a concentration of 3.91 to 1000 µg/mL and could reduce the oxidative damage of cells caused by H2O2. PGC-CDs could inhibit the increase levels of bilirubin and inflammation factors and increase the levels of antioxidants and survival rate, demonstrating that PGC-CDs possessed anti-inflammatory and anti-oxidation activity. PGC-CDs may reduce the content of bilirubin, so as to reduce a series of pathological lesions caused by bilirubin, which has potential in treating hyperbilirubinemia and preventing liver damage induced by hyperbilirubinemia.

In Utero Antiretroviral Exposure and Risk of Neurodevelopmental Problems in HIV-Exposed Uninfected 5-Year-Old Children

Studies have observed neurodevelopmental (ND) challenges among young children perinatally HIV-exposed yet uninfected (CHEU) with in utero antiretroviral (ARV) exposure, without clear linkage to specific ARVs. Atazanavir (ATV) boosted with ritonavir has been a preferred protease inhibitor recommended for pregnant women, yet associations of ATV with ND problems in CHEU have been reported. Studies among early school-age children are lacking. The pediatric HIV/AIDS cohort study (PHACS) surveillance monitoring for antiretroviral therapy (ART) toxicities (SMARTT) study evaluated 5-year-old monolingual English-speaking CHEU using the behavior assessment system for children, Wechsler preschool and primary scales of intelligence, and test of language development-primary. A score ≥1.5 standard deviations worse than population norms defined a signal within each domain. Analyses of risk for signals were stratified by timing of any ARV initiation. Associations between ARV exposure and risk of ND signals were assessed using proportional odds models, adjusting for confounders. Among 230 children exposed to ARVs at conception, 15% had single and 8% had multiple ND problems; ATV exposure was not associated with higher risk of signals [adjusted cumulative odds ratio (cOR) = 0.66, confidence interval (CI): 0.28-1.56]. However, among 461 children whose mothers initiated ARVs during pregnancy, 21% had single and 12% had multiple ND problems; ATV exposure was associated with higher risk of signals (cOR = 1.70, CI: 0.82-3.54). The specific regimen tenofovir/emtricitabine/ATV was associated with higher risk (cOR = 2.31, CI: 1.08-4.97) relative to regimens using a zidovudine/lamivudine backbone combined with non-ATV ARVs. It remains important to monitor neurodevelopment of CHEU during early childhood and investigate the impact and the role of timing of in utero exposure to specific ARVs.

Effects of bilirubin on the development and electrical activity of neural circuits

In the past several decades, bilirubin has attracted great attention for central nervous system (CNS) toxicity in some pathological conditions with severely elevated bilirubin levels. CNS function relies on the structural and functional integrity of neural circuits, which are large and complex electrochemical networks. Neural circuits develop from the proliferation and differentiation of neural stem cells, followed by dendritic and axonal arborization, myelination, and synapse formation. The circuits are immature, but robustly developing, during the neonatal period. It is at the same time that physiological or pathological jaundice occurs. The present review comprehensively discusses the effects of bilirubin on the development and electrical activity of neural circuits to provide a systematic understanding of the underlying mechanisms of bilirubin-induced acute neurotoxicity and chronic neurodevelopmental disorders.

A prediction model for short-term neurodevelopmental impairment in preterm infants with gestational age less than 32 weeks

Introduction

Early identification and intervention of neurodevelopmental impairment in preterm infants may significantly improve their outcomes. This study aimed to build a prediction model for short-term neurodevelopmental impairment in preterm infants using machine learning method.

Methods

Preterm infants with gestational age  < 32 weeks who were hospitalized in The Maternal and Child Health Hospital of Guangxi Zhuang Autonomous Region, and were followed-up to 18 months corrected age were included to build the prediction model. The training set and test set are divided according to 8:2 randomly by Microsoft Excel. We firstly established a logistic regression model to screen out the indicators that have a significant effect on predicting neurodevelopmental impairment. The normalized weights of each indicator were obtained by building a Support Vector Machine, in order to measure the importance of each predictor, then the dimension of the indicators was further reduced by principal component analysis methods. Both discrimination and calibration were assessed with a bootstrap of 505 resamples.

Results

In total, 387 eligible cases were collected, 78 were randomly selected for external validation. Multivariate logistic regression demonstrated that gestational age(p = 0.0004), extrauterine growth restriction (p = 0.0367), vaginal delivery (p = 0.0009), and hyperbilirubinemia (0.0015) were more important to predict the occurrence of neurodevelopmental impairment in preterm infants. The Support Vector Machine had an area under the curve of 0.9800 on the training set. The results of the model were exported based on 10-fold cross-validation. In addition, the area under the curve on the test set is 0.70. The external validation proves the reliability of the prediction model.

Conclusion

A support vector machine based on perinatal factors was developed to predict the occurrence of neurodevelopmental impairment in preterm infants with gestational age  < 32 weeks. The prediction model provides clinicians with an accurate and effective tool for the prevention and early intervention of neurodevelopmental impairment in this population.

Models of bilirubin neurological damage: lessons learned and new challenges

OBJECTIVE

Jaundice (icterus) is the visible manifestation of the accumulation of bilirubin in the tissue and is indicative of potential toxicity to the brain. Since its very first description more than 2000 years ago, many efforts have been undertaken to understand the molecular determinants of bilirubin toxicity to neuronal cells to reduce the risk of neurological sequelae through the use of available chemicals and in vitro, ex vivo, in vivo, and clinical models. Although several studies have been performed, important questions remain unanswered, such as the reasons for regional sensitivity and the interplay with brain development. The number of new molecular effects identified has increased further, which has added even more complexity to the understanding of the condition. As new research challenges emerged, so does the need to establish solid models of prematurity.

METHODS

This review critically summarizes the key mechanisms of severe neonatal hyperbilirubinemia and the use of the available models and technologies for translational research.

IMPACT

We critically review the conceptual dogmas and models used for studying bilirubin-induced neurotoxicity. We point out the pitfalls and translational gaps, and suggest new clinical research challenges. We hope to inform researchers on the pro and cons of the models used, and to help direct their experimental focus in a most translational research.

Bilirubin-Induced Neurological Damage: Current and Emerging iPSC-Derived Brain Organoid Models

Bilirubin-induced neurological damage (BIND) has been a subject of studies for decades, yet the molecular mechanisms at the core of this damage remain largely unknown. Throughout the years, many in vivo chronic bilirubin encephalopathy models, such as the Gunn rat and transgenic mice, have further elucidated the molecular basis of bilirubin neurotoxicity as well as the correlations between high levels of unconjugated bilirubin (UCB) and brain damage. Regardless of being invaluable, these models cannot accurately recapitulate the human brain and liver system; therefore, establishing a physiologically recapitulating in vitro model has become a prerequisite to unveil the breadth of complexities that accompany the detrimental effects of UCB on the liver and developing human brain. Stem-cell-derived 3D brain organoid models offer a promising platform as they bear more resemblance to the human brain system compared to existing models. This review provides an explicit picture of the current state of the art, advancements, and challenges faced by the various models as well as the possibilities of using stem-cell-derived 3D organoids as an efficient tool to be included in research, drug screening, and therapeutic strategies for future clinical applications.

Vascular network expansion, integrity of blood-brain interfaces, and cerebrospinal fluid cytokine concentration during postnatal development in the normal and jaundiced rat

BACKGROUND

Severe neonatal jaundice resulting from elevated levels of unconjugated bilirubin in the blood induces dramatic neurological impairment. Central oxidative stress and an inflammatory response have been associated with the pathophysiological mechanism. Cells forming the blood-brain barrier and the choroidal blood-CSF barrier are the first CNS cells exposed to increased plasma levels of unconjugated bilirubin. These barriers are key regulators of brain homeostasis and require active oxidative metabolism to fulfill their protective functions. The choroid plexus-CSF system is involved in neuroinflammatory processes. In this paper, we address the impact of neonatal hyperbilirubinemia on some aspects of brain barriers. We describe physiological changes in the neurovascular network, blood-brain/CSF barriers integrities, and CSF cytokine levels during the postnatal period in normobilirubinemic animals, and analyze these parameters in parallel in Gunn rats that are deficient in bilirubin catabolism and develop postnatal hyperbilirubinemia.

METHODS

Gunn rats bearing a mutation in UGT1a genes were used. The neurovascular network was analyzed by immunofluorescence stereomicroscopy. The integrity of the barriers was evaluated by [14C]-sucrose permeability measurement. CSF cytokine levels were measured by multiplex immunoassay. The choroid plexus-CSF system response to an inflammatory challenge was assessed by enumerating CSF leukocytes.

RESULTS

In normobilirubinemic animals, the neurovascular network expands postnatally and displays stage-specific regional variations in its complexity. Network expansion is not affected by hyperbilirubinemia. Permeability of the blood-brain and blood-CSF barriers to sucrose decreases between one- and 9-day-old animals, and does not differ between normobilirubinemic and hyperbilirubinemic rats. Cytokine profiles differ between CSF and plasma in all 1-, 9-, and 18-day-old animals. The CSF cytokine profile in 1-day-old animals is markedly different from that established in older animals. Hyperbilirubinemia perturbs these cytokine profiles only to a very limited extent, and reduces CSF immune cell infiltration triggered by systemic exposure to a bacterial lipopeptide.

CONCLUSION

The data highlight developmental specificities of the blood-brain barrier organization and of CSF cytokine content. They also indicate that a direct effect of bilirubin on the vascular system organization, brain barriers morphological integrity, and inflammatory response of the choroid plexus-CSF system is not involved in the alteration of brain functions induced by severe neonatal jaundice.

Molecular Genetic Screening of Neonatal Intensive Care Units: Hyperbilirubinemia as an Example

Objective

To explore the clinical value of newborn genomic screening (nGS) for neonatal intensive care units (NICU) infants (taking neonatal hyperbilirubinemia as an example).

Methods

Dried blood spots (DBSs) were collected after 72 hours of birth. The tandem mass spectrometry (TMS) screening and Angel Care genomic screening (GS, based on Targeted next-generation sequencing) were performed at the same time.

Results

Ninety-six hyperbilirubinemia newborns were enrolled in this study and none was identified with inborn errors of metabolism (IEM) by TMS, while 6 infants (6.25%, 6/96) were suspected to have a genetic disorder by Angel Care, including 2 cases of glucose-6-phosphate dehydrogenase deficiency (G6PD), and 1 case of maple syrup urine disease type 1B (MSUD1B), autosomal recessive deafness 1A (DFNB1A), Leber hereditary optic neuropathy (LHON), thyroid dyshormonogenesis 6 (TDH6) each. In addition, 44 infants (45.8%) were detected having at least one variant which conferred a carrier status for a recessive childhood-onset disorder. A total of 33 out of 60 variants (55.0%) reported for carrier status were pathogenic (P), 24 (40.0%) were likely pathogenic (LP), and 3 variants were variant of uncertain significance (VUS). Top six common genes of carrier status were GJB2, DUOX2, PRODH, ATP7B, SLC12A3, SLC26A4. Two newborns showed abnormalities in elementary screening of TMS, but were confirmed as false positive after recall. Their results of Angel Care did not found abnormality.

Conclusion

Using neonatal hyperbilirubinemia as an example, genome sequencing screening can find more evidence of genetic variation in NICU newborns, and “Angel Care” is an effective method.

Normalizing hyperactivity of the Gunn rat with bilirubin-induced neurological disorders via ketanserin

BACKGROUND

Severe neonatal hyperbilirubinemia has been known to cause the clinical syndrome of kernicterus and a milder one the syndrome of bilirubin-induced neurologic dysfunction (BIND). BIND clinically manifests itself after the neonatal period as developmental delay, cognitive impairment, and related behavioral and psychiatric disorders. The complete picture of BIND is not clear.

METHODS

The Gunn rat is a mutant strain of the Wistar rat with the BIND phenotype, and it demonstrates abnormal behavior. We investigated serotonergic dysfunction in Gunn rats by pharmacological analyses and ex vivo neurochemical analyses.

RESULTS

Ketanserin, the 5-HT2AR antagonist, normalizes hyperlocomotion of Gunn rats. Both serotonin and its metabolites in the frontal cortex of Gunn rats were higher in concentrations than in control Wistar rats. The 5-HT2AR mRNA expression was downregulated without alteration of the protein abundance in the Gunn rat frontal cortex. The TPH2 protein level in the Gunn rat raphe region was significantly higher than that in the Wistar rat.

CONCLUSIONS

It would be of value to be able to postulate that a therapeutic strategy for BIND disorders would be the restoration of brain regions affected by the serotonergic dysfunction to normal operation to prevent before or to normalize after onset of BIND manifestations.

IMPACT

We demonstrated serotonergic dysregulation underlying hyperlocomotion in Gunn rats. This finding suggests that a therapeutic strategy for bilirubin-induced neurologic dysfunction (BIND) would be the restoration of brain regions affected by the serotonergic dysfunction to normal operation to prevent before or to normalize after the onset of the BIND manifestations. Ketanserin normalizes hyperlocomotion of Gunn rats. To our knowledge, this is the first study to demonstrate a hyperlocomotion link to serotonergic dysregulation in Gunn rats.

Breastfeeding Insufficiencies: Common and Preventable Harm to Neonates

Insufficient milk intake in breastfed neonates is common, frequently missed, and causes preventable hospitalizations for jaundice/hyperbilirubinemia, hypernatremia/dehydration, and hypoglycemia - accounting for most U.S. neonatal readmissions. These and other consequences of neonatal starvation and deprivation may substantially contribute to fully preventable morbidity and mortality in previously healthy neonates worldwide. Previous advanced civilizations recognized this problem of breastfeeding insufficiencies and had an infrastructure to solve it: Wetnursing, shared nursing, and prelacteal feeding traditions used to be well-organized and widespread. Modern societies accidentally destroyed that infrastructure. Then, modern reformers missing a few generations of direct knowledge transmission about safe breastfeeding invented a new, historically anomalous conception of breastfeeding defined in terms of exclusivity. As that new intervention has become increasingly widespread, so too have researchers widely reported associated possible harms of the longer neonatal starvation/deprivation and later infant under-nutrition periods that it creates when breastfeeding is insufficient. Early insufficient nutrition/hydration has possible long-term effects including neurodevelopmental consequences such as attention deficit hyperactivity disorder, autism, cerebral palsy, cognitive and developmental delay, epilepsy, hearing impairment, kernicterus, language disorder, mood disorders, lower IQ, and specific learning disorder. Current early infant feeding guidelines conflict with the available evidence. Recent reform efforts have tended to focus on using more technology and measurement to harm fewer neonates instead of proposing the indicated paradigm shift in early infant feeding to prevent more harm. The scientific evidence is already sufficient to mandate application of the precautionary principle to feed neonates early, adequate, and often milk before mothers' milk comes in and whenever signs of hunger persist, mitigating possible risks including death or disability. In most contexts, the formula is the best supplementary milk for infants at risk from breastfeeding insufficiencies. National-level reviews of scientific evidence, health policy, and research methods and ethics are needed to initiate the early infant feeding paradigm shift that the data already support. Policy experiments and related legislative initiatives might also contribute to the shift, as insurers might decline or be required by law to decline reimbursing hospitals for costs of this type of preventable hospitalization, which otherwise generates profit.

The Association between Serum Bilirubin and Kernicterus Spectrum Disorder: A Systematic Review and Meta-Analysis

BACKGROUND

Total serum bilirubin (TSB) is used in managing neonates with jaundice, but clear evidence on its association with major outcomes is lacking.

OBJECTIVES

We evaluated the association between TSB and kernicterus spectrum disorder (KSD).

METHODS

We searched PubMed, EMBASE, and CENTRAL till July 2021. Two authors independently selected relevant cohort studies, extracted data (CHARMS checklist), assessed risk of bias (RoB) (QUIPS tool), and rated certainty-of-evidence (Grades of Recommendation, Assessment, Development, and Evaluation). We pooled adjusted odds ratio (aOR) (random-effect) via generic inverse variance methods.

RESULTS

From 2,826 records retrieved, we included 37 studies (n = 648,979). Fifteen studies had low, 16 moderate, and 6 high RoB, with majority having concerns on confounder adjustment and statistical analysis. Twenty-two studies contributed meta-analysis data, and 15 were summarized narratively. TSB appears associated with KSD in infants with certain risk factors (aOR 1.10, 95% CI: 1.07-1.13; 5 studies [n = 4,484]). However, TSB (aOR 1.10, 95% CI: 0.98-1.23; 1 study [n = 34,533]) or hyperbilirubinemia (aOR 1.00, 95% CI: 0.51-1.95; 2 studies [n = 56,578]) have no clear association with kernicterus or neurological diagnosis in overall neonatal population (moderate-certainty-evidence). One study shows that infants with hyperbilirubinemia appear likelier to develop attention-deficit disorder (aOR 1.90, 95% CI: 1.10-3.28) and autistic spectrum disorder (aOR 1.60, 95% CI: 1.03-2.49, n = 56,019) (low-certainty-evidence). Certain clinical factors appear associated with KSD, although very few studies contributed to the analyses.

CONCLUSIONS

Despite the importance of this question, there is insufficient high-quality evidence on the independent prognostic value of TSB for adverse neurodevelopmental outcomes in most neonatal populations. Future studies should incorporate all known risk factors alongside TSB in a multivariable analysis to improve certainty-of-evidence.

Molecular Physiology and Pathophysiology of Bilirubin Handling by the Blood, Liver, Intestine, and Brain in the Newborn

Bilirubin is the end product of heme catabolism formed during a process that involves oxidation-reduction reactions and conserves iron body stores. Unconjugated hyperbilirubinemia is common in newborn infants, but rare later in life. The basic physiology of bilirubin metabolism, such as production, transport, and excretion, has been well described. However, in the neonate, numerous variables related to nutrition, ethnicity, and genetic variants at several metabolic steps may be superimposed on the normal physiological hyperbilirubinemia that occurs in the first week of life and results in bilirubin levels that may be toxic to the brain. Bilirubin exists in several isomeric forms that differ in their polarities and is considered a physiologically important antioxidant. Here we review the chemistry of the bilirubin molecule and its metabolism in the body with a particular focus on the processes that impact the newborn infant, and how differences relative to older children and adults contribute to the risk of developing both acute and long-term neurological sequelae in the newborn infant. The final section deals with the interplay between the brain and bilirubin and its entry, clearance, and accumulation. We conclude with a discussion of the current state of knowledge regarding the mechanism(s) of bilirubin neurotoxicity.

A Gunn rat model of preterm hyperbilirubinemia

BACKGROUND

The impact of bilirubin in preterm infants is poorly understood. An animal model would assist in improving understanding. The Gunn rat lacks uridine diphosphate-glucuronylsyl transferase 1 and can be made acutely hyperbilirubinemic by injection of sulfodimethoxine (sulfa), a drug that displaces bilirubin from albumin and thus increases free bilirubin.

METHODS

On postnatal day (P) 5, Gunn rats either heterozygous (Nj) or homozygous (jj) for glucuronosyltransferase activity were injected with either saline or sulfa. Behavior and cerebellar weight were measured.

RESULTS

Pups did not show any signs of acute bilirubin encephalopathy. Pup weight dropped significantly on P8 only in the jj-sulfa group. Behavior was affected only in the jj-sulfa group. Cerebellar weight was significantly less in the jj-sulfa group.

CONCLUSION

The Gunn rat pup model may be a good model to study hyperbilirubinemia in preterm infants.