-
Journal of Hepatology Dec 2021Bilirubin is a tetrapyrrolic compound originating from heme catabolism. Although originally considered only a potentially dangerous waste product, it has become...
Bilirubin is a tetrapyrrolic compound originating from heme catabolism. Although originally considered only a potentially dangerous waste product, it has become increasingly evident that this molecule represents an important modulator of various biological functions in the human body. Bilirubin appears to have versatile functions, from cell signaling (behaving almost like a "real" hormonal substance), modulation of metabolism, to immune regulation, affecting biological activities with apparent clinical and even therapeutic consequences. These activities may be the reason for the lower incidence of diseases of civilisation (cardiovascular diseases, arterial hypertension, diabetes, obesity, metabolic syndrome, certain cancers, autoimmune, and neurodegenerative diseases) observed in individuals with a chronic mild unconjugated hyperbilirubinemia, a typical sign of Gilbert's syndrome. While higher serum concentrations of unconjugated bilirubin may serve as an important protective factor against these diseases, low levels of bilirubin are associated with the opposite effect.
Topics: Bilirubin; Color; Heme; Humans; Hyperbilirubinemia
PubMed: 34153399
DOI: 10.1016/j.jhep.2021.06.010 -
Liver International : Official Journal... May 2008Bilirubin is an endogenous compound that can be toxic under certain conditions but, on the other hand, mild unconjugated hyperbilirubinaemia might protect against... (Review)
Review
Bilirubin is an endogenous compound that can be toxic under certain conditions but, on the other hand, mild unconjugated hyperbilirubinaemia might protect against cardiovascular diseases and tumour development. Serum bilirubin levels are often enhanced under a variety of clinical conditions. These are discussed and the mechanisms are outlined.
Topics: Bilirubin; Humans; Hyperbilirubinemia; Molecular Structure
PubMed: 18433389
DOI: 10.1111/j.1478-3231.2008.01716.x -
Biotechnology Letters Oct 2017Bilirubin detection plays a major role in healthcare. Its high concentration in human serum is lethal and must be determined accurately. Clinically, it is vital for... (Review)
Review
Bilirubin detection plays a major role in healthcare. Its high concentration in human serum is lethal and must be determined accurately. Clinically, it is vital for assessing patients with deleterious health conditions such as jaundice or icterus, hepatitis, mental disorders, cerebral palsy and brain damage especially in the case of neonates. In evaluating the drawbacks regarding the conventional methodology of bilirubin detection, there is need for a superior analytical tool. Bilirubin oxidase (BOx)-based sensors have been designed for the ultrasensitive analysis of bilirubin and quality deliverance of treatment and this review highlights the different mechanisms of bilirubin detection using different modified electrodes. Further, it also addresses the exploitation of highly attractive electrocatalytic properties of elite nanoparticles such as gold and zirconia- coated silica nanoparticles in enhancing the reproducibility and specificity of bilirubin biosensors.
Topics: Bilirubin; Biosensing Techniques; Catalysis; Gold; Humans; Metal Nanoparticles; Models, Molecular; Oxidoreductases Acting on CH-CH Group Donors; Reproducibility of Results; Zirconium
PubMed: 28726079
DOI: 10.1007/s10529-017-2396-0 -
Annals of Clinical Biochemistry Mar 1991The most widely used methods for the assay of total bilirubin in serum are based on a coupling reaction with various diazo dyes in the presence of an accelerating agent.... (Review)
Review
The most widely used methods for the assay of total bilirubin in serum are based on a coupling reaction with various diazo dyes in the presence of an accelerating agent. The 'direct' reaction, without accelerator, gives a good estimate of the conjugated and protein bound (delta) species of bilirubin only if carefully standardized reaction conditions are used. Enzymatic methods based on bilirubin oxidase appear to give similar results, for both total and direct bilirubin, and through difficult to calibrate, spectrophotometric methods can also give reliable results for total bilirubin at the higher concentrations seen in neonates. More sophisticated HPLC or dry-slide techniques are required for the specific assay of the various conjugated and protein-bound species of bilirubin in serum.
Topics: Bilirubin; Chromatography, High Pressure Liquid; Coloring Agents; Diazonium Compounds; Humans; Quality Control; Spectrophotometry
PubMed: 1859150
DOI: 10.1177/000456329102800202 -
Seminars in Fetal & Neonatal Medicine Jun 2010Despite a century of research, several clinically relevant areas of bilirubin biochemistry remain controversial, poorly understood, or unrecognized. These include: (i)... (Review)
Review
Despite a century of research, several clinically relevant areas of bilirubin biochemistry remain controversial, poorly understood, or unrecognized. These include: (i) The structure and molecularity of bilirubin under physiological environments such as membranes, brain tissue and when bound to proteins. Related to this is the large number of structurally different bilirubin species that may occur in blood under pathological conditions and their potential effects on measurements of bilirubin and free bilirubin. (ii) The mechanism of phototherapy, the neurotoxicity of the photoisomers produced and their influence on measurements of bilirubin and free bilirubin. (iii) The role of membrane transporters in the passage of unconjugated bilirubin across the placenta, intestine, vascular epithelium, blood-brain barrier, and into the liver. (iv) Biochemical mechanisms of bilirubin toxicity, pharmacologic prevention of kernicterus, the contribution of bilirubin to antioxidant defenses, and the practical value of free bilirubin measurements for identifying infants at most risk of kernicterus.
Topics: Animals; Bilirubin; Biliverdine; Humans; Hyperbilirubinemia, Neonatal; Infant, Newborn; Liver; Models, Molecular; Phototherapy
PubMed: 19932645
DOI: 10.1016/j.siny.2009.10.005 -
Critical Reviews in Clinical Laboratory... 1991Bilirubin fractions are measured by (1) the direct diazo reaction, (2) high-performance liquid chromatography (HPLC), (3) direct spectrophotometry, and (4) enzymatic... (Comparative Study)
Comparative Study Review
Bilirubin fractions are measured by (1) the direct diazo reaction, (2) high-performance liquid chromatography (HPLC), (3) direct spectrophotometry, and (4) enzymatic methods. HPLC, which effects separation and quantitation of the four bilirubin fractions, is the method of choice, but impractical for routine use. A special application of direct spectrophotometry allows the measurement of unconjugated bilirubin and the sum of bilirubin conjugates. This approach, which provides essentially the same information as HPLC, unfortunately is available only in one clinical analyzer. The direct diazo reaction measures bilirubin conjugates plus delta-bilirubin, albeit not very accurately. Direct diazo methods that measure unconjugated bilirubin as direct could obscure the clinical diagnosis. At acid pH, enzymatic methods measure all direct reacting bilirubins, while at pH 10 only conjugated bilirubins are measured. Because the measurement of conjugated bilirubins is clearly more helpful than that of direct bilirubin in the differential diagnosis of jaundice, direct diazo methods should be replaced by methods specific for bilirubin conjugates.
Topics: Azo Compounds; Bilirubin; Chromatography, High Pressure Liquid; Humans; Molecular Structure; Oxidoreductases; Oxidoreductases Acting on CH-CH Group Donors; Reference Standards; Spectrophotometry
PubMed: 1772588
DOI: 10.3109/10408369109106872 -
Advances in Clinical Chemistry 2010This review examines in vitro and in vivo studies, indicating that bilirubin inhibits lipid oxidation and oxygen radical formation. Experimental and epidemiological... (Review)
Review
This review examines in vitro and in vivo studies, indicating that bilirubin inhibits lipid oxidation and oxygen radical formation. Experimental and epidemiological evidence is presented that suggests that bilirubin may serve as a physiological antioxidant providing protection against cardiovascular disease. Special attention is focused on large prospective studies that noted a strong, inverse relationship between serum bilirubin concentrations and cardiovascular morbidity and mortality even after adjustment for traditional risk factors. Overall, the evidence from these studies suggests that bilirubin, via its antioxidant potential, has antiatherogenic properties, and that serum bilirubin concentrations in the upper portion of the reference interval for the general population may provide some protection against cardiovascular disease, whereas concentrations in the lower portion of the reference interval indicate increased cardiovascular risk.
Topics: Bilirubin; Biomarkers; Cardiovascular Diseases; Humans; Hyperbilirubinemia; Risk Factors
PubMed: 20521440
DOI: 10.1016/s0065-2423(10)50003-9 -
Folia Microbiologica 1991The strong effects of bilirubin on various levels of the immune system are multifactorial. Concerning the mechanisms of these effects, we hypothesize that the primary... (Review)
Review
The strong effects of bilirubin on various levels of the immune system are multifactorial. Concerning the mechanisms of these effects, we hypothesize that the primary causes of the described actions of bilirubin are the direct interaction of bilirubin molecules with cell membranes.
Topics: Bilirubin; Humans; Immunosuppressive Agents
PubMed: 1823644
DOI: 10.1007/BF02814488 -
Nihon Rinsho. Japanese Journal of... Feb 1995
-
World Journal of Gastroenterology Jun 2002In this paper, we summarize the main progresses made in our group in the field of the mechanism of pigment gallstone formation. It was found that after treatment with... (Review)
Review
In this paper, we summarize the main progresses made in our group in the field of the mechanism of pigment gallstone formation. It was found that after treatment with free radicals, bilirubin (BR) was changed into free radical itself, and a semiquinone free radical and a superoxide free radical bound with metal were recognized, which was detected by ESR (electron spin resonance). By the means of NMR (nuclear magnetic resonance) and IR (Infra-red spectra), it was postulated that bilirubin polymerized through the reaction between the vinyl group and the hydroxyl group under the attack of free radicals. It was also found that bilirubin free radical were liable to calcify in a kinetic study. Because of its chemical properties, bilirubin free radical was shown to be cytotoxic to hepatocyte, which was demonstrated based on the following facts: induction of phospholipid peroxidation (LPO), leakage of lactate dehydrogenase (LDH) and decrease of glutathione. As to the mechanism of bilirubin-induced cytotoxicity, it was postulated that the main target of bilirubin free radical was the cell membrane, including phospholipid and membrane bound proteins, especially spectrin, a content of cytoskeleton. Based on the results mentioned above, it was deduced that bilirubin free radical is the key factor that initiates and promotes the formation of pigment gallstone, which is consistent with other researches in recent years.
Topics: Bilirubin; Cholelithiasis; Electron Spin Resonance Spectroscopy; Free Radicals; Humans; Pigments, Biological
PubMed: 12046060
DOI: 10.3748/wjg.v8.i3.413