Toxic effects in the Gunn rat of combined treatment with bilirubin and orotic acid

Hyperbilirubinemia exaggerates endotoxin-induced hypothermia

Systemic inflammation is accompanied by an increased production of reactive oxygen species (ROS) and by either fever or hypothermia (or both). To study aseptic systemic inflammation, it is often induced in rats by the intravenous administration of bacterial lipopolysaccharide (LPS). Knowing that bilirubin is a potent ROS scavenger, we compared responses to LPS between normobilirubinemic Gunn rats (heterozygous, asymptomatic; J/+) and hyperbilirubinemic Gunn rats (homozygous, jaundiced; J/J) to establish whether ROS mediate fever and hypothermia in aseptic systemic inflammation. These two genotypes correspond to undisturbed versus drastically suppressed (by bilirubin) tissue accumulation of ROS, respectively. A low dose of LPS (10 μg/kg) caused a typical triphasic fever in both genotypes, without any intergenotype differences. A high dose of LPS (1,000 μg/kg) caused a complex response consisting of early hypothermia followed by late fever. The hypothermic response was markedly exaggerated, whereas the subsequent fever response was strongly attenuated in J/J rats, as compared to J/+ rats. J/J rats also tended to respond to 1,000 μg/kg with blunted surges in plasma levels of all hepatic enzymes studied (alanine aminotransferase, aspartate aminotransferase, gamma-glutamyl transferase), thus suggesting an attenuation of hepatic damage. We propose that the reported exaggeration of LPS-induced hypothermia in J/J rats occurs via direct inhibition of nonshivering thermogenesis by bilirubin and possibly via a direct vasodilatatory action of bilirubin in the skin. This hypothermia-exaggerating effect might be responsible, at least in part, for the observed tendency of J/J rats to be protected from LPS-induced hepatic damage. The attenuation of the fever response to 1,000 μg/kg could be due to either direct actions of bilirubin on thermoeffectors or the ROS-scavenging action of bilirubin. However, the experiments with 10 μg/kg strongly suggest that ROS signaling is not involved in the fever response to low doses of LPS.

Management of hyperbilirubinemia and prevention of kernicterus in 20 patients with Crigler-Najjar disease

We summarize the treatment of 20 patients with Crigler-Najjar disease (CND) managed at one center from 1989 to 2005 (200 patient-years). Diagnosis was confirmed by sequencing the UGTA1A gene. Nineteen patients had a severe (type 1) phenotype. Major treatment goals were to maintain the bilirubin to albumin concentration ratio at <0.5 in neonates and <0.7 in older children and adults, to avoid drugs known to displace bilirubin from albumin, and to manage temporary exacerbations of hyperbilirubinemia caused by illness or gallstones. A variety of phototherapy systems provided high irradiance over a large body surface. Mean total bilirubin for the group was 16+/-5 mg/dl and increased with age by approximately 0.8 mg/dl per year. The molar ratio of bilirubin to albumin ranged from 0.17 to 0.75 (mean: 0.44). The overall non-surgical hospitalization rate was 0.12 hospitalizations per patient per year; one-half of these were for neonatal hyperbilirubinemia and the remainder were for infectious illnesses. Ten patients (50%) underwent elective laproscopic cholecystectomy for cholelithiasis. No patient required invasive bilirubin removal or developed bilirubin-induced neurological damage under our care. Visual acuity and color discrimination did not differ between CND patients and age-matched sibling controls. Four patients treated with orthotopic liver transplantation were effectively cured of CND, although one suffered significant transplant-related complications.Conclusions. While patients await liver transplantation for CND, hyperbilirubinemia can be managed safely and effectively to prevent kernicterus. Lessons learned from CND can be applied to screening and therapy of non-hemolytic jaundice in otherwise healthy newborns.

Changes in body temperature after administration of antipyretics, LSD, delta 9-THC, CNS depressants and stimulants, hormones, inorganic ions, gases, 2,4-DNP and miscellaneous agents

This survey concludes a series of complications of data from the literature, primarily published since 1965, on thermoregulatory effects of antipyretics in afebrile as well as in febrile subjects, LSD and other hallucinogens, cannabinoids, general CNS depressants, CNS stimulants including xanthines, hormones, inorganic ions, gases and fumes, 2,4-dinitrophenol and miscellaneous agents including capsaicin, cardiac glycosides, chemotherapeutic agents, cinchona alkaloids, cyclic nucleotides, cycloheximide, 2-deoxy-D-glucose, dimethylsulfoxide, insecticides, local anesthetics, poly I:poly C, spermidine and spermine, sugars, toxins and transport inhibitors. The information listed includes the species used, route of administration and dose of drug, the environmental temperature at which the experiments were performed, the number of tests, the direction and magnitude of body temperature change and remarks on the presence of special conditions such as age or lesions, or on the influence of other drugs, such as antagonists, on the response to the primary agents.