Bilirubin oxidation products, oxidative stress, and intracerebral hemorrhage

Abstract

Hematoma and perihematomal regions after intracerebral hemorrhage (ICH) are biochemically active environments known to undergo potent oxidizing reactions. We report facile production of bilirubin oxidation products (BOXes) via hemoglobin/Fenton reaction under conditions approximating putative in vivo conditions seen following ICH. Using a mixture of human hemoglobin, physiological buffers, unconjugated solubilized bilirubin, and molecular oxygen and/or hydrogen peroxide, we generated BOXes, confirmed by spectral signature consistent with known BOXes mixtures produced by independent chemical synthesis, as well as HPLC-MS of BOX A and BOX B. Kinetics are straightforward and uncomplicated, having initial rates around 0.002 microM bilirubin per microM hemoglobin per second under normal experimental conditions. In hematomas from porcine ICH model, we observed significant production of BOXes, malondialdehyde, and superoxide dismutase, indicating a potent oxidizing environment. BOX concentrations increased from 0.084 +/- 0.01 in fresh blood to 22.24 +/- 4.28 in hematoma at 72h, and were 11.22 +/- 1.90 in adjacent white matter (nmol/g). Similar chemical and analytical results are seen in ICH in vivo, indicating the hematoma is undergoing similar potent oxidations. This is the first report of BOXes production using a well-defined biological reaction and in vivo model of same. Following ICH, amounts of unconjugated bilirubin in hematoma can be substantial, as can levels of iron and hemoglobin. Oxidation of unconjugated bilirubin to yield bioactive molecules, such as BOXes, is an important discovery, expanding the role of bilirubin in pathological processes seen after ICH.

External ventricular drainage alone versus endoscopic surgery for severe intraventricular hemorrhage: a comparative retrospective analysis on outcome and shunt dependency

“…4,8,16,20,26,36,37,51 Intraventricular blood brings about multiple noxious effects 10,13 on the brain causing impairment of CSF circulation, 29 intracranial hypertension, 19 and acute 14 or delayed hydrocephalus. 15 Mortality estimates for IVH range from 50% to 80%.…”

“…24 Blood may remain for weeks after hemorrhage; acute clots obstruct ventricular CSF pathways, and clot degradation products obstruct extraventricular CSF pathways. When present, blood degradation products continue to contribute to patients' poor clinical statuses 5,6,[9][10][11] and are responsible for chronic shunt-dependent hydrocephalus in more than 30% of them. [15][16][17]30 At present, reduction in the ventricular clot size seems to be the only method for reducing mortality rates after the ICH has stabilized.…”

Bilirubin and its Oxidation Products Damage Brain White Matter

“…Although direct effects of BOXes on white matter were not assessed here, the importance of BOXes is supported by studies detecting BOXes in brain tissue around experimental ICH. 12,32 Compounds with other molecular weights were identified and their contribution to toxicity needs to be determined.…”

Effects of the blood components on the AMPA and NMDA synaptic responses in brain slices in the onset of hemorrhagic stroke

“…As is known, after a cerebral hemorrhage, oxidations in the hematoma produce a cocktail of dangerous metabolites released into the brain's parenchyma (Wagner et al 2003;Clark et al 2008). To investigate if excitation of glutamatergic EPSPs and inhibition of GABA B ergic IPSPs observed in piriform cortex in the onset of perfusion with autologous blood was dependent on the influence of different products of blood (clot) degradation, we performed experiments to examine the changes of synaptic activity in slices under the influence of the fractions derived from the blood centrifugation.…”