A new rat model of neonatal bilirubin encephalopathy (kernicterus).

INTRODUCTION: Hemolytic kernicterus, an indirect bilirubin-induced brain dysfunction, is associated with hyper-bilirubinemia in mammalian neonates. In this study, a new model of kernicterus has been developed using intra-peritoneal injections of phenyl hydrazine and subcutaneous injections of sulfisoxazole. These drugs can potentially induce kernicterus in neonatal through changes in hemolysis and hypo-albumin. METHODS: For this purpose, 7-day-old male Wistar rats (n=72; mean weight 11±1g) were used. The animals have been divided into six different groups which received the drugs alone and their combination, and the drugs' solvents and their combination. Biochemical parameters, brain iron and bilirubin, behavioural performance, auditory function and apoptosis were measured using auto-analyser instruments; atomic absorption spectroscopy, Sawasaki, footprint, auditory brainstem response (ABR) and TUNEL test, respectively. RESULT: The drug-injected groups showed a significant reduction in serum haematocrit and an increase in the concentration of brain bilirubin, total and indirect bilirubin as well as TUNEL positive cells in basal ganglia. In addition, the obtained results showed that there was a significant increase in behavioural disturbance and auditory dysfunction in the group injected with the combination of two drugs. CONCLUSION: This kernicterus-induced rat model could perfectly mimic the common conditions of the hyperbilirubinemia in human neonates. This study offers an easy technique to develop more stable models for follow-up studies.

Efficacy of Human Adipose Tissue-Derived Stem Cells on Neonatal Bilirubin Encephalopathy in Rats.

Kernicterus is a neurological syndrome associated with indirect bilirubin accumulation and damages to the basal ganglia, cerebellum and brain stem nuclei particularly the cochlear nucleus. To mimic haemolysis in a rat model such that it was similar to what is observed in a preterm human, we injected phenylhydrazine in 7-day-old rats to induce haemolysis and then infused sulfisoxazole into the same rats at day 9 to block bilirubin binding sites in the albumin. We have investigated the effectiveness of human adiposity-derived stem cells as a therapeutic paradigm for perinatal neuronal repair in a kernicterus animal model. The level of total bilirubin, indirect bilirubin, brain bilirubin and brain iron was significantly increased in the modelling group. There was a significant decreased in all severity levels of the auditory brainstem response test in the two modelling group. Akinesia, bradykinesia and slip were significantly declined in the experience group. Apoptosis in basal ganglia and cerebellum were significantly decreased in the stem cell-treated group in comparison to the vehicle group. All severity levels of the auditory brainstem response tests were significantly decreased in 2-month-old rats. Transplantation results in the substantial alleviation of walking impairment, apoptosis and auditory dysfunction. This study provides important information for the development of therapeutic strategies using human adiposity-derived stem cells in prenatal brain damage to reduce potential sensori motor deficit.

A novel newborn rat kernicterus model created by injecting a bilirubin solution into the cisterna magna.

BACKGROUND: Kernicterus still occurs around the world; however, the mechanism of bilirubin neurotoxicity remains unclear, and effective treatment strategies are lacking. To solve these problems, several kernicterus (or acute bilirubin encephalopathy) animal models have been established, but these models are difficult and expensive. Therefore, the present study was performed to establish a novel kernicterus model that is simple and affordable by injecting unconjugated bilirubin solution into the cisterna magna (CM) of ordinary newborn Sprague-Dawley (SD) rats. METHODS: On postnatal day 5, SD rat pups were randomly divided into bilirubin and control groups. Then, either bilirubin solution or ddH2O (pH = 8.5) was injected into the CM at 10 µg/g (bodyweight). For model characterization, neurobehavioral outcomes were observed, mortality was calculated, and bodyweight was recorded after bilirubin injection and weaning. Apoptosis in the hippocampus was detected by H&E staining, TUNEL, flow cytometry and Western blotting. When the rats were 28 days old, learning and memory ability were evaluated using the Morris water maze test. RESULTS: The bilirubin-treated rats showed apparently abnormal neurological manifestations, such as clenched fists, opisthotonos and torsion spasms. Bodyweight gain in the bilirubin-treated rats was significantly lower than that in the controls (P<0.001). The early and late mortality of the bilirubin-treated rats were both dramatically higher than those of the controls (P = 0.004 and 0.017, respectively). Apoptosis and necrosis in the hippocampal nerve cells in the bilirubin-treated rats were observed. The bilirubin-treated rats performed worse than the controls on the Morris water maze test. CONCLUSION: By injecting bilirubin into the CM, we successfully created a new kernicterus model using ordinary SD rats; the model mimics both the acute clinical manifestations and the chronic sequelae. In particular, CM injection is easy to perform; thus, more stable models for follow-up study are available.

Cotrimoxazole and neonatal kernicterus: a review.

Sulfamethoxazole (SMX) and trimethoprim (TMP) individually and a combination known as cotrimoxazole (SMX-TMP) are widely used for the treatment of protozoan and bacterial infections. SMX-TMP is also one of the widely used antibiotics administered orally in neonates, along with gentamicin injection, for treating pneumonia and sepsis by home-based healthcare providers in Asian countries. Although the use of this drug has successfully reduced neonate mortality, there is a concern for it causing neurotoxicity. Previous clinical studies with sulfisoxazole have demonstrated occurrence of kernicterus in neonates. This sulfonamide is thought to displace bilirubin from its albumin-binding sites in plasma leading to an elevation of plasma bilirubin, which crosses the blood-brain barrier, reaches central neurons to cause kernicterus. We performed an extensive review of clinical and animal studies with cotrimoxazole, which showed no reported incidences of kernicterus with SMX-TMP use in neonates. EndNote, BasicBiosis, Embase, PubMed and Toxline database searches were conducted using specific keywords yielding 74 full-length articles relevant to the review. This review has taken into account various factors, including the disease itself, direct effects of the drug and its metabolism through conjugation and acetylation through a thorough review of the literature to examine the potentials of SMX-TMP to cause kernicterus in neonates. SMX-TMP in oral doses administered to neonates for 7-10 days is unlikely to cause kernicterus. Also, this review recommends warranting the need of future studies using animal models and clinical studies in humans to address SMX-TMP toxicity.

Elevated levels of bilirubin and long-term exposure impair human brain microvascular endothelial cell integrity.

The pathogenesis of encephalopathy by unconjugated bilirubin (UCB) seems to involve the passage of high levels of the pigment across the blood-brain barrier (BBB) and the consequent damage of neuronal cells. However, it remains to be clarified if and how the disruption of BBB occurs by UCB. We used confluent monolayers of human brain microvascular endothelial cells (HBMEC) to explore the sequence of events produced by UCB. A cell line and primary cultures of HBMEC were exposed to 50 or 100 µM UCB, in the presence of 100 µM human serum albumin, to mimic moderate and severe jaundice, for 1-72 h. UCB caused loss of cell viability in a concentration-dependent manner. UCB inhibited the secretion of interleukin-6, interleukin-8, monocyte chemoattractant protein-1 and vascular endothelial growth factor at early time points, but enhanced their secretion at later time points. Upregulation of mRNA expression, particularly by 100 µM UCB, preceded cytokine secretion. Other early events include the disruption of glutathione homeostasis and the increase in endothelial nitric oxide synthase expression followed by nitrite production. Prolonged exposure to UCB upregulated the expression of ß-catenin and caveolin-1. In conclusion, elevated concentrations of UCB affect the integrity of HBMEC monolayers mediated by oxidative stress and cytokine release. UCB also induced increased expression of caveolin-1, which has been associated with BBB breakdown, and ß-catenin, probably as an attempt to circumvent that impairment. These findings provide a basis for target-directed therapy against brain endothelial injury caused by UCB.

Quantification of gait in dystonic Gunn rats.

Spontaneously jaundiced Gunn rats exposed to sulfadimethoxine develop bilirubin encephalopathy (kernicterus) with hearing loss and dystonia, closely resembling the human syndrome. We recently characterized the electromyographic activity in this animal model supporting our clinical impression of dystonia. The objective of this study was to develop a simple, non-invasive method to quantify the motor deficits in dystonic rodents. On postnatal day 16, Gunn rats were treated with 100mg/kg of sulfadimethoxine or saline. On postnatal day 31, the ventral view of the animals was videotaped while the animals walked inside a Plexiglas chamber. Individual video frames were reviewed and specific gait parameters including hindlimb spread, step length ratio variability, stance/swing ratio and walking speed were compared between dystonic and non-dystonic jaundiced and non-jaundiced littermates. Data analysis demonstrated statistically significant increases in hindlimb spread and step length ratio variability and decreases in walking speed in dystonic animals as compared to controls. This study demonstrates a valuable technique to objectively characterize dystonia in Gunn rats, which could have wide use for other experimental movement disorders as well.

Experimental hemolysis model to study bilirubin encephalopathy in rat brain.

None of experimental models used to study the toxic effect of unconjugated bilirubin brain accumulation, reproduce the conditions in which the hyperbilirubinemia is a consequence of a hemolytic process, i.e. when important amounts of bilirubin and iron are released. The aim was to develop an animal model to determine the role of bilirubin and iron, in the encephalopathy secondary to a hemolytic disease. Male Wistar rats 7 days old (n=30) were treated with phenylhydrazine as hemolytic at 75 mg/kg body weight intraperitoneally for 2 days and euthanized 24 h after the last dose. Hemoglobin, hematocrit, serum and brain bilirubin, serum iron and lipoperoxidation products, as well as neuronal damage and iron positive staining were evaluated and compared among treated and untreated (n=10) animals. The animals with induced hemolysis showed significant reduction in hemoglobin and hematocrit, increased concentration of total and conjugated bilirubin, as well as of serum iron and lipid peroxidation products. The neuronal damage in treated animals included the presence of altered neurons spread out among normal cells, as well as of iron-staining positive cells. With the use of appropriated pharmacological procedures, the characteristics of the model can be useful to dissect the participation of both bilirubin and iron, on the bilirubin encephalopathy secondary to hemolysis.

Safety and toxicity of sulfadoxine/pyrimethamine: implications for malaria prevention in pregnancy using intermittent preventive treatment.

Plasmodium falciparum infection during pregnancy is strongly associated with maternal anaemia and low birth weight, contributing to substantial morbidity and mortality in sub-Saharan Africa. Intermittent preventive treatment in pregnancy with sulfadoxine/pyrimethamine (IPTp-SP) has been one of the most effective approaches to reduce the burden of malaria during pregnancy in Africa. IPTp-SP is based on administering >or=2 treatment doses of sulfadoxine/pyrimethamine to pregnant women at predefined intervals after quickening (around 18-20 weeks). Randomised, controlled trials have demonstrated decreased rates of maternal anaemia and low birth weight with this approach. The WHO currently recommends IPTp-SP in malaria-endemic areas of sub-Saharan Africa. However, implementation has been suboptimal in part because of concerns of potential drug toxicities. This review evaluates the toxicity data of sulfadoxine/pyrimethamine, including severe cutaneous adverse reactions, teratogenicity and alterations in bilirubin metabolism. Weekly sulfadoxine/pyrimethamine prophylaxis is associated with rare but potentially fatal cutaneous reactions. Fortunately, sulfadoxine/pyrimethamine use in IPTp programmes in Africa, with 2-4 treatment doses over 6 months, has been well tolerated in multiple IPTp trials. However, sulfadoxine/pyrimethamine should not be administered concurrently with cotrimoxazole given their redundant mechanisms of action and synergistic worsening of adverse drug reactions. Therefore, HIV-infected pregnant women in malaria endemic areas who are already receiving cotrimoxazole prophylaxis should not also receive IPTp-SP. Although folate antagonist use in the first trimester is associated with neural tube defects, large case-control studies have demonstrated that sulfadoxine/pyrimethamine administered as IPTp (exclusively in the second and third trimesters and after organogenesis) does not result in an increased risk of teratogenesis. Folic acid supplementation is recommended for all pregnant women to reduce the rate of congenital anomalies but high doses of folic acid (5 mg/day) may interfere with the antimalarial efficacy of sulfadoxine/pyrimethamine. However, the recommended standard dose of folic acid supplementation (0.4 mg/day) does not affect antimalarial efficacy and may provide the optimal balance to prevent neural tube defects and maintain the effectiveness of IPTp-SP. No clinical association between sulfadoxine/pyrimethamine use and kernicterus has been reported despite the extensive use of sulfadoxine/pyrimethamine and related compounds to treat maternal malaria and congenital toxoplasmosis in near-term pregnant women and newborns. Although few drugs in pregnancy can be considered completely safe, sulfadoxine/pyrimethamine - when delivered as IPTp - has a favourable safety profile. Improved pharmacovigilance programmes throughout Africa are now needed to confirm its safety as access to IPTp-SP increases. Given the documented benefits of IPTp-SP in malaria endemic areas of Africa, access to this treatment for pregnant women should continue to expand.

[Investigation of Coptis chinensis on jaundice of glucose-6-phosphate dehydrogenase (G6PD) deficient neonates from Guigang, Guangxi province].

OBJECTIVE: To investigate the effect of Coptis chinensis on jaundice of G6PD deficient neonates. METHOD: 122 G6PD deficient neonates with jaundice who were in People' s Hospital of Guigang of Guangxi province from January 1999 to October 2004 were divided into two groups: C. chinensis group (62 neonates with C. chinensis administration before jaundice' s appearance) and none C. chinensis group (60 neonates without C. chinensis administration before jaundice' s appearance). The initial time, duration of jaundice, hemoglobin and serum bilirubin level and the incidence of kernicterus were analyzed between the two groups. RESULT: The initial time of jaundice is significantly later and the duration of jaundice is markedly shorter in the neonates with C. chinensis than that without C. chinensis. Simultaneously, the level of hemoglobin is significantly increased, and there is a low tendency of serum total bilirubin and direct bilirubin level in C. chinensis group as compared to that in none C. chinensis group. Moreover, there is no kernicterus in C. chinensis group and no difference in the treating result out of hospital between the two groups. CONCLUSION: Our results do not support the view that C. chinensis could aggravate jaundice of G6PD deficient neonates.

Somatosensory and brainstem auditory evoked potentials in the Gunn rat model of acute bilirubin neurotoxicity.

Brainstem auditory evoked potentials (BAEPs) are a sensitive indicator of bilirubin neurotoxicity. Somatosensory evoked potentials (SEPs) have been proposed as another measure of toxicity, though the lemniscal pathways that generate the SEP are not involved in kernicterus. In 16 to 17-d-old jaundiced (jj) Gunn rats, serial BAEPs and SEPs were obtained up to 8 h after acute bilirubin toxicity. jjs were injected with 150 mg/kg sulfadimethoxine to displace bilirubin into brain tissue (n = 8); littermate controls were jjs given saline (n = 4) and nonjaundiced given sulfadimethoxine or saline (n = 7). After anesthesia, BAEP and SEP recordings were obtained at baseline and serially after injection. SEPs to median nerve stimulation were recorded from surface electrodes over the brachial plexus (Erb's) and contralateral parietal cortex, and subtracted to obtain central conduction time (CCT). There were no statistically significant different baseline values between groups. Baseline BAEP I, I-II, and I-III were 1.22 +/- 0.13, 1.11 +/- 0.12, and 2.10 +/- 0.15 ms, and SEP Erb's and CCT were 1.48 +/- 0.20 and 5.59 +/- 0.50 ms, respectively (n = 19). At 6.8 +/- 1.5 h after injection BAEP I, I-II, and I-III increased 0.10 +/- 0.08, 0.18 +/- 0.17, and 0.56 +/- 0.33 ms over baseline, respectively (p = 0.005, 0.01, and 0.001, respectively, paired, 1-tailed t-tests), in experimental but not control groups. SEP Erb's decreased slightly, -0.06 +/- 0.04 ms in experimental and -0.08 +/- 0.08 ms in control groups, while CCT did not change significantly. BAEPs were completely abolished in two jjs with no SEP changes. When injection of sulfonamide induced significant peripheral and central BAEP abnormalities in jaundiced rats, no SEP abnormalities occurred. SEPs assess proprioception but not other somatosensory function or sensory integration. The results demonstrate the selectivity of acute bilirubin toxicity for the auditory nervous system.

Displacement of bilirubin from albumin by berberine.

A study was made of the effect of berberine, the major ingredient of the Chinese herb huanglian (coptis chinensis) reported to pose some risk for kernicterus among jaundiced newborn Chinese infants, on the protein binding of bilirubin, using the peroxidase kinetic method. Berberine was found in vitro, as to its displacing effect on a molar basis, to be about tenfold superior to phenylbutazone, a known potent displacer of bilirubin, and about hundredfold to papaverine, a berberine-type alkaloid. The chronic intraperitoneal administration of berberine (10 and 20 micrograms/g) daily for 1 week to adult rats (mixed breed of Wistar and Sprague-Dawley) resulted in a significant decrease in mean bilirubin serum protein binding, due to an in vivo displacement effect and a persistent elevation in steady-state serum concentrations of unbound and total bilirubin, possibly due to inhibition of metabolism. The use of the herb and other traditional Chinese medicines containing a high proportion of berberine is best avoided in jaundiced neonates and pregnant women.

[The risks of pyrimethamine-sulfadoxine combination in the prenatal treatment of toxoplasmosis]. / Les risques de l'association pyriméthamine-sulfadoxine dans le traitement anténatal de la toxoplasmose.

Some of the alternative treatments to avoid termination of pregnancy in cases where the fetus is affected by toxoplasmosis is to treat it as soon as the diagnosis has been made. The authors who already have experience of using pyrimethamine with sulfadoxoine (Fansidar) in the post-natal treatment of congenital infection, thought after reviewing the literature that this association of drugs would be harmless if applied during pregnancy. The principal risk that arises in the fetus is the teratogenicity of each of the components of pyrimethamine and sulfadoxine and also their associations. In animals pyrimethamine can increase the frequency of cleft palates probably because of its antifolinic action but there is no formal proof that it is teratogenic in human beings. Furthermore, the theoretical risk of karnicerus in the new born using the Sulfonamide has not been demonstrated. In the mother the main but rare risk (1 in 75,000) seems to be for the production of severe skin lesions such as Lyell and Stevens-Johnson which could be brought about by sulfonamides, but not particularly sulfadoxine.

Risk factors associated with kernicterus in the newborn infant: importance of benzyl alcohol exposure.

The prevalence of kernicterus in our neonatal intensive care unit (NICU) decreased from more than 2/1000 live births in 1980 to none in 1984. To clarify predictors of kernicterus, we examined the medical records of infants born during that time who died between 2 and 28 days of age. Infants were divided into three groups: those with kernicterus, all born before June 10, 1982 (n = 29); contemporaneous controls (n = 28); and infants born after June 10, 1982 (n = 32). Benzyl alcohol was not used after June 10, 1982. Kernicteric infants were more likely than contemporaneous controls to have seizures (p less than 0.001). Indices of pulmonary disease, arterial partial pressure of carbon dioxide and end-expiratory pressure on the ventilator were higher after 1982. However, exposure to benzyl alcohol was not different in kernicteric infants and contemporaneous controls, suggesting that benzyl alcohol exposure was not the explanation for the decrease in the prevalence of kernicterus in our NICU.

Relationship of benzyl alcohol to kernicterus, intraventricular hemorrhage, and mortality in preterm infants.

Intraventricular hemorrhage and death in preterm neonates has been associated with the use of fluid containing benzyl alcohol, a bacteriostatic agent, to flush intravascular catheters. The hospital and autopsy records of infants admitted to a nursery during the last 18 months that benzyl alcohol was in use (218 patients) were reviewed and compared with those of infants admitted in the first 18 months after benzyl alcohol was withdrawn (232 patients). The volume of flush solution administered to each patient was estimated. Exposure to benzyl alcohol was significantly associated with the development of kernicterus (P less than .005), and intraventricular hemorrhage (P less than .000,000,5). Kernicterus did not develop in any patient after benzyl alcohol was withdrawn. Many patients with kernicterus or intraventricular hemorrhages received small daily volumes of fluid containing benzyl alcohol. Withdrawal of benzyl alcohol from clinical use had no demonstrable effect on mortality. Medications intended for neonatal use should not contain benzyl alcohol. Our data indicate that patients not exposed to benzyl alcohol have a greatly reduced risk of kernicterus. If this finding is confirmed by other investigators, present indications for exchange transfusions in preterm infants with moderate elevations of serum bilirubin should be reconsidered.