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Seminars in Perinatology Jun 2011In 2003, the Chemistry Resource Committee of the College of American Pathologists introduced a new specimen in the Neonatal Bilirubin Survey. The specimen, consisting of...
In 2003, the Chemistry Resource Committee of the College of American Pathologists introduced a new specimen in the Neonatal Bilirubin Survey. The specimen, consisting of human serum enriched with unconjugated bilirubin and thus resembling a clinical specimen, brought about an improvement in the accuracy of the measurement of bilirubin by laboratories participating in the Neonatal Bilirubin Survey. There was also an improvement in the specificity of methods measuring direct bilirubin. However, persisting inaccuracies and variability in laboratory performance have been traced to calibrators consisting of bovine serum spiked with unconjugated bilirubin and ditaurobilirubin; bovine serum causes underestimation of both bilirubins by 8 major chemical analyzers. To eradicate inaccuracy calibrators and Survey specimens should be made in human instead of bovine serum.
Topics: Bilirubin; Chemistry, Clinical; Humans; Infant, Newborn; Isomerism; Reference Values; Reproducibility of Results; Spectrophotometry; United States
PubMed: 21641487
DOI: 10.1053/j.semperi.2011.02.008 -
Hepatology (Baltimore, Md.) Apr 1993
Review
Topics: Animals; Bile; Bilirubin; Biological Transport; Humans; Liver; Models, Biological
PubMed: 8477977
DOI: 10.1002/hep.1840170428 -
Transplantation Jun 2007
Topics: Bilirubin; Biomarkers; Humans; Liver Function Tests; Liver Transplantation; Reperfusion Injury
PubMed: 17589355
DOI: 10.1097/01.tp.0000266996.25289.6c -
Acta Neurochirurgica. Supplement 2008Bilirubin oxidation products (BOXes) have been a subject of interest in neurosurgery because they are purported to be involved in subarachnoid hemorrhage induced...
Bilirubin oxidation products (BOXes) have been a subject of interest in neurosurgery because they are purported to be involved in subarachnoid hemorrhage induced cerebral vasospasm. There is a growing body of information concerning their putative role in vasospasm; however, there is a dearth of information concerning the chemical and biochemical characteristics of BOXes. A clearer understanding of the synthesis, stability and characteristics of BOXes will be important for a better understanding of the role of BOXes post subarachnoid hemorrhage. We used hydrogen peroxide to oxidize bilirubin and produce BOXes. BOXes were extracted and analyzed using conventional methods such as HPLC and mass spectrometry. Characterization of the stability of BOXes demonstrates that light can photodegrade BOXes with a t1/2 of up to 10h depending upon conditions. Mixed isomers of BOXes have an apparent extinction coefficient of epsilon = 6985, and a lambda(max) of 310 nm. BOXes are produced by the oxidation of bilirubin, yielding a mixture of isomers: 4-methyl-5-oxo-3-vinyl-(1,5-dihydropyrrol-2-ylidene)acetamide (BOX A) and 3-methyl-5-oxo-4-vinyl-(1,5-dihydropyrrol-2-ylide-ne)acetamide (BOX B). The BOXes are photodegraded by ambient light and can be analyzed spectrophotometrically with their extinction coefficient as well as with HPLC or mass spectrometry. Their small molecular weight and photodegradation may have made them difficult to characterize in previous studies.
Topics: Bilirubin; Drug Stability; Hydrogen Peroxide; Mass Spectrometry; Models, Molecular; Oxidation-Reduction; Photochemistry
PubMed: 18456996
DOI: 10.1007/978-3-211-75718-5_8 -
The Journal of Clinical Investigation Nov 1969This report describes studies of bilirubin kinetics in 13 healthy young adults. The plasma content of unconjugated bilirubin-(14)C was determined at frequent intervals...
This report describes studies of bilirubin kinetics in 13 healthy young adults. The plasma content of unconjugated bilirubin-(14)C was determined at frequent intervals for 24-30 hr after the intravenous injection of a tracer dose of unconjugated isotopic bilirubin. Fecal and urinary radioactivity were measured for 7 days. During this time cumulative recovery averaged 96% of the injected dose. The plasma curves were processed by digital computer. For the 30 hr experimental period, a sum of three exponentials, with average half-times of 18, 81, and 578 min, was required to describe the data. Using the plasma curve integral method, the hepatic bilirubin clearance (47 +/-10 ml/min, mean +/-SD), the bilirubin production rate (3.8 +/-0.6 mg/kg per day), and the mean red blood cell life span (101 +/-13 days) were calculated directly from the parameters of this function. To gain further insight into the metabolism of unconjugated bilirubin, the data were also used to determine the parameters of a multicompartmental model. In the model proposed, plasma unconjugated bilirubin exchanges with two additional pools one of which is thought to represent extrahepatic extravascular, and the other intrahepatic unconjugated bilirubin. Bilirubin is eliminated from the system via the proposed intrahepatic pool. From the data and the model, pool sizes and exchange rates between compartments were calculated, and the liver: plasma concentration gradient estimated. These studies provide a detailed analysis of the kinetics of unconjugated bilirubin in a healthy normal population and are intended to serve as a reference point for studies of abnormal states.
Topics: Adult; Bile; Bilirubin; Carbon Isotopes; Computers; Erythrocyte Aging; Feces; Female; Humans; Kinetics; Liver; Male; Metabolic Clearance Rate
PubMed: 5824077
DOI: 10.1172/JCI106184 -
Free Radical Biology & Medicine Sep 2010Bilirubin reportedly protects cultured cells from the toxicity of a 10,000-fold molar excess of H(2)O(2). A bilirubin-biliverdin cycling mechanism has been proposed to...
Bilirubin reportedly protects cultured cells from the toxicity of a 10,000-fold molar excess of H(2)O(2). A bilirubin-biliverdin cycling mechanism has been proposed to explain this remarkable effect whereby bilirubin reacts with oxyradicals specifically generating biliverdin, which is then reduced back to bilirubin by NADPH/biliverdin reductase. Chemical evidence for this mechanism was formation of biliverdin during incubation of bilirubin-albumin with 2,2'-azobis(2-amidinopropane) hydrochloride (AAPH) in vitro and the assumption that biliverdin was formed by the reaction of peroxyl radicals with bilirubin. This paper describes spectroscopic studies on the reaction of bilirubin with AAPH in the presence and absence of human serum albumin. Reactions were run in air and also under oxygen-depleted and oxygen-saturated solutions, the former to inhibit peroxyl radical formation, the latter to augment it. The results confirm that degradation of bilirubin, rather than dehydrogenation to biliverdin, predominates in the reaction of bilirubin with peroxyl radicals generated by AAPH thermolysis. They also suggest that biliverdin produced in the presence of albumin is not formed by the reaction of bilirubin with alkyl peroxyl radicals, as previously assumed. The observations undermine the plausibility of the bilirubin-biliverdin recycling mechanism proposed to explain the reported hyperprotective effect of bilirubin on mammalian cells exposed to excess H(2)O(2).
Topics: Amidines; Antioxidants; Bilirubin; Biliverdine; Catalysis; Cytoprotection; Humans; In Vitro Techniques; Oxidants; Oxygen; Spectrum Analysis
PubMed: 20547221
DOI: 10.1016/j.freeradbiomed.2010.06.001 -
Preparative Biochemistry & Biotechnology 2022The UnaG protein is a ligand (unconjugated bilirubin) dependent fluorescence protein isolated from Unagi freshwater eel larvae and expressed as fusion in heterologous...
Investigation of mutations (L41F, F17M, N57E, Y99F_Y134W) effects on the TolAIII-UnaG fluorescence protein's unconjugated bilirubin (UC-BR) binding ability and thermal stability properties.
The UnaG protein is a ligand (unconjugated bilirubin) dependent fluorescence protein isolated from Unagi freshwater eel larvae and expressed as fusion in heterologous expression systems. Bilirubin is a tetrapyrrole molecule mainly produced from heme catabolism by the destruction of erythrocytes in the body. Bilirubin can cause kernicterus, a serious condition associated with permanent neurological damage in neonates with the passage of brain tissue. Different methods have been developed for plasma bilirubin analysis and quantification. The use of UnaG fluorescence protein triggered by bilirubin has become a new approach in bilirubin studies. In this study, we aimed to investigate the biophysical characterization of ligand interactions with the proteins obtained as a result of mutations (UnaG, UnaG, UnaG, and UnaG) on the amino acid sequence of TolAIII-UnaG protein. After the purity levels of the expressed proteins have been analyzed by SDS-PAGE, secondary structures and thermal melting temperatures of the proteins have been examined by circular dichroism spectroscopy. Then determination of excitation and emission points by fluorescence spectroscopy, titration studies have been performed with bilirubin, and dissociation constant was calculated. According to the biophysical characterization studies, UnaG has the highest affinity and stability among the mutants.
Topics: Amino Acid Sequence; Bilirubin; Humans; Infant, Newborn; Ligands; Mutation; Spectrometry, Fluorescence
PubMed: 34319856
DOI: 10.1080/10826068.2021.1952597 -
Archives of Internal Medicine Feb 1971
Topics: Adult; Anemia, Sickle Cell; Bilirubin; Humans
PubMed: 5101152
DOI: No ID Found -
CRC Critical Reviews in Clinical... Jan 1980
Review
Topics: Animals; Bilirubin; Binding Sites; Brain Diseases; Humans; Hydrogen-Ion Concentration; Infant, Newborn; Protein Binding; Protein Conformation; Serum Albumin
PubMed: 6985857
DOI: No ID Found -
Organic Letters Sep 2016Four endogenous products of oxidative bilirubin degradation were isolated and fully characterized. The constitutional isomers belong to the propentdyopents (PDPs). Their...
Four endogenous products of oxidative bilirubin degradation were isolated and fully characterized. The constitutional isomers belong to the propentdyopents (PDPs). Their structures and further oxidative transformations to biologically active bilirubin oxidation end products (Z-BOXes) are reported. Using liquid chromatography-mass spectrometry protocols, PDPs were detected in human bile and gallstones. Given the recent interest in BOXes as effectors in cerebral vasospasms and liver dysfunction, co-occurring PDPs represent an additional potentially active compound class to be considered.
Topics: Bilirubin; Chromatography, Liquid; Humans; Mass Spectrometry; Molecular Structure; Oxidation-Reduction
PubMed: 27528398
DOI: 10.1021/acs.orglett.6b02287