Increased urinary excretion of bilirubin oxidative metabolites in septic patients: a new marker for oxidative stress in vivo

A Platform for the Synthesis of Oxidation Products of Bilirubin

Bilirubin is the principal product of heme catabolism. High concentrations of the pigment are neurotoxic, yet slightly elevated levels are beneficial. Being a potent antioxidant, oxidative transformations of bilirubin occur in vivo and lead to various oxidized fragments. The mechanisms of their formation, intrinsic biological activities, and potential roles in human pathophysiology are poorly understood. Degradation methods have been used to obtain samples of bilirubin oxidation products for research. Here, we report a complementary, fully synthetic method of preparation. Our strategy leverages repeating substitution patterns in the parent tetracyclic pigment. Functionalized ready-to-couple γ-lactone, γ-lactam, and pyrrole monocyclic building blocks were designed and efficiently synthesized. Subsequent modular combinations, supported by metal-catalyzed borylation and cross-coupling chemistries, translated into the concise assembly of the structurally diverse bilirubin oxidation products (BOXes, propentdyopents, and biopyrrins). The discovery of a new photoisomer of biopyrrin A named lumipyrrin is reported. Synthetic bilirubin oxidation products made available in sufficient purity and quantity will support future in vitro and in vivo investigations.

Caspofungin pharmacokinetics and probability of target attainment in ICU patients in China

OBJECTIVES

Effective antifungal therapy is important to reduce mortality in patients with invasive fungal infections (IFIs). Numerous factors affect pharmacokinetic/pharmacodynamic (PK/PD) parameters in critically-ill patients. To guide individualised administration in critically-ill patients, it is of great significance to determine the population pharmacokinetics of caspofungin.

METHODS

A prospective study in 42 ICU patients with IFIs was conducted in China. A population pharmacokinetic model of caspofungin was established using a non-linear mixed-effects model, which was utilised to investigate the effects of demographic indices, liver function and kidney function on pharmacokinetics. Additionally, appropriate dosages of caspofungin under various scenarios were determined based on MICs and probability of target attainment (PTA) at specific dosages.

RESULTS

In critically-ill Chinese patients, clearance (CL), volume of distribution (V) and area under the curve at steady-state (AUC_ss) of caspofungin were 0.32 L/h, 6.77 L and 135.47 mg•h/L, respectively. Blood albumin and total bilirubin levels were factors affecting CL, while body weight was the only factor affecting V among Chinese people with relatively low weight compared with other populations. A maintenance dose of 50 mg caspofungin achieved a high PTA for treating IFIs caused by Candida albicans (MIC ≤ 0.06 mg/L) and Candida glabrata (MIC ≤ 0.125 mg/L). The maintenance dose of caspofungin should be adjusted to 70-200 mg for IFIs caused by C. albicans (MIC, 0.06-0.125 mg/L). For IFIs caused by Candida parapsilosis, an MIC > 0.03 mg/L is associated with a very low PTA, but higher doses of caspofungin or alternative antifungals need to be further studied.

CONCLUSION

The population pharmacokinetic model established here described well the PK/PD characteristics of caspofungin in critically-ill Chinese patients. These results could guide the formulation of individualised caspofungin dosing regimens for critically-ill patients.

Reference urinary biopyrrin level and physiological variation in healthy young adults: relation of stress by learning

Background

Biopyrrins are end products of oxidation reactions of bilirubin with reactive oxygen, and urinary biopyrrin (UBP) levels might increase under oxidative stress. The authors examined the reference UBP level for healthy adults and its physiological variation in 40 healthy volunteers recruited from among students of our university (20 students each from third-year and fourth-year), and compared the results with data on 8-hydroxy-2-deoxyguanosine (8OHdG).

Methods

UBP and 8OHdG levels could be considered as oxidative stress markers. The UBP levels were measured with a competitive ELISA kit using biopyrrin antibody 24G7, according to the manufacturer's protocol. 8OHdG levels were measured with a Highly Sensitive 8-OHdG Check kit. UBP and 8OHdG measurements were performed in triplicate and means values calculated. For both parameters, creatinine (Cr) correction was performed using urinary creatinine levels measured by an enzymatic method.

Results

A comparison of the UBP levels between different grades revealed that the third-year students under high stress from clinical training and other course work tended to have a higher UBP level than fourth-year students. Therefore, we compared the current UBP levels in fourth-year students (samples collected in 2018) with their UBP level when they were in the third-year (samples collected in 2017) to examine the annual change. We found that the UBP level in 2017 samples was significantly higher than that in 2018 samples (P < 0.05). No difference in the 8OHdG level. Additionally, no effect of menstrual stress on the UBP level was observed.

Conclusions

These results suggest that the UBP levels may be related to school-related stress and menstruation has no effects on urinalysis results.

Analysis of oxidative stress expressed by urinary level of biopyrrins and 8-hydroxydeoxyguanosine in patients with chronic schizophrenia

AIMS

Previous studies have supported the claim that psychological stress induces the production of reactive oxygen species. Several authors have suggested that patients with psychiatric disorders show high levels of oxidative stress markers. We examined different oxidative stress markers in patients with chronic schizophrenia.

METHODS

This study included 29 patients with chronic schizophrenia and 30 healthy volunteers. The concentration of urinary biopyrrins and 8-hydroxydeoxyguanosine (8-OHdG), as measured by enzyme-linked immunosorbent assay, were normalized to the urinary concentration of creatinine. Psychiatric symptoms were assessed by the administration of the Brief Psychiatric Rating Scale (BPRS).

RESULTS

The concentration of biopyrrins in patients with chronic schizophrenia was significantly higher when compared with healthy volunteers. The correlation between biopyrrin level and the duration of illness was highly significant. There were no significant differences in the levels of urinary 8-OHdG between the two groups. In schizophrenic patients, the level of urinary biopyrrins showed correlations with BPRS scores, while the level of urinary 8-OHdG did not show correlations with BPRS.

CONCLUSIONS

Urinary biopyrrins are increased in patients with chronic schizophrenia while urinary 8-OHdG is not increased. These findings suggest that patients with chronic schizophrenia are under the condition of certain oxidative stresses.

Serum total bilirubin elevation is a predictor of the clinicopathological severity of acute appendicitis

PURPOSE

Elevation of the serum total bilirubin (STB) level not stemming from hepatic dysfunction or biliary obstruction may be seen in cases of acute appendicitis. This paper deals with the clinical significance of such elevations.

METHODS

Data from 410 appendectomized patients classified into two groups (a high preoperative STB group and a normal preoperative STB group) were analyzed to reveal the significance of preoperative hyperbilirubinemia. We also examined whether the preoperative STB level might serve as a risk factor for gangrenous appendicitis by a multivariate analysis.

RESULTS

Gangrenous appendicitis was more common in the high preoperative STB group (p < 0.001). The multivariate analysis revealed that an elevated preoperative STB level (odds ratio 1.7919) was a risk factor for gangrenous appendicitis.

CONCLUSION

In patients with an elevated preoperative STB level, it is very likely that the inflammation is severe and that the disease has progressed to a severe condition histopathologically; therefore, meticulous attention should be paid to the selection of the surgical procedure, as well as to the postoperative clinical course.

Tandem mass spectrometry of bilin tetrapyrroles by electrospray ionization and collision-induced dissociation

RATIONALE

Bilins are metabolic products of hosts and bacteria on porphyrins, and are markers of health state and human waste contamination. Although bilin tandem mass spectrometry reports exist, their fragmentation behavior as a function of structure has not been compared, nor has fragmentation been examined as a function of collision energy.

METHODS

The fragmentation of bilins generated by positive ion mode electrospray ionization is examined by collision-induced dissociation (CID). CID on a quadrupole ion trap and on a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer as a function of collision energy is compared. Methyl esterification was used to deduce which product ions contain the inner pyrrole rings. FT-ICR high mass accuracy measurements were used to determine the formulas of the resultant product ions.

RESULTS

The central carbon's bonding to the inner pyrrole rings influences fragmentation. Bilirubin is unique because fragmentation adjacent to the central methylene group between innermost rings predominates, and loss of a terminal pyrrole is observed only with helium collision gas. The other bilins lose the terminal pyrroles first; as CID energy is increased, additional fragmentation due to neutral losses of small molecules such as H(2)O, CO, CO(2), and methanol occurs.

CONCLUSIONS

Based on these observations, fragmentation schemes for the bilins are proposed that are strongly dependent on the molecular structure and collision energy; only bilirubin fragmentation is influenced significantly by the collision gas used. This report should have value in identification of this class of molecules for biomarker detection.

Urinary biopyrrins: potential biomarker for monitoring of the response to treatment with anxiolytics

During periods of psychological stress, excess amounts of free radicals are produced. Bilirubin oxidative metabolites (biopyrrins; BOM) are generated from bilirubin as a result of its scavenging action against free radicals. We investigated whether the urinary excretion of biopyrrins is altered by anxiolytics. In the present study, mice were immobilized for a period of 6 hr. Alprazolam (0.1-1 mg/kg of body-weight) was administered 30 min. before subjecting the animals to acute stress. The BOM concentrations in urine and the corticosterone levels in serum were measured by ELISA with an anti-bilirubin antibody and EIA, respectively. We observed an increase in urinary biopyrrins in stressed mice in comparison with non-stressed mice and a decrease after the treatment of stressed animals with alprazolam. A correlation between urinary BOM and serum corticosterone levels was found. Urinary levels of biopyrrins might be used to assess the response to anxiolytics prescribed during acute stress periods.

Sepsis biomarkers: a review

INTRODUCTION

Biomarkers can be useful for identifying or ruling out sepsis, identifying patients who may benefit from specific therapies or assessing the response to therapy.

METHODS

We used an electronic search of the PubMed database using the key words "sepsis" and "biomarker" to identify clinical and experimental studies which evaluated a biomarker in sepsis.

RESULTS

The search retrieved 3370 references covering 178 different biomarkers.

CONCLUSIONS

Many biomarkers have been evaluated for use in sepsis. Most of the biomarkers had been tested clinically, primarily as prognostic markers in sepsis; relatively few have been used for diagnosis. None has sufficient specificity or sensitivity to be routinely employed in clinical practice. PCT and CRP have been most widely used, but even these have limited ability to distinguish sepsis from other inflammatory conditions or to predict outcome.

Relationship between treatment resistance to hemoperfusion using a polymyxin B-immobilized fiber column and oxidative stress

Recently, the existence of a relationship was reported between the severity of lung injury and the serum level of F2-isoprostane, a known oxidative stress marker. Recent reports have suggested that direct hemoperfusion with a polymyxin B-immobilized fiber column (DHP-PMX) may improve the oxygenation in patients with acute lung injury and acute respiratory distress syndrome. Because cases of septic shock associated with respiratory diseases have poor outcomes, we selected cases of septic shock associated with respiratory disease to review the characteristics of the treatment-resistant cases. We treated 13 septic shock cases due to respiratory disease using DHP-PMX. The patients were separated into 2 groups for analysis from oxygenation effect immediately after DHP-PMX: A group (7 cases) PaO2/FiO2 ratio increased more than 20%; B group (6 cases) PaO2/FiO2 ratio did not increase more than 20%. Factors were measured before DHP-PMX. The average Acute Physiology and Chronic Health Evaluation II score was 31.2 +/- 9.4, and the average sequential organ failure assessment score was 15.1 +/- 5.3 before DHP-PMX. Four patients survived and 9 died. Only the F2-Isoprostane level was significantly high in B group (p = 0.0228). A relationship between F2-Isoplostane and rebellious cases by DHP-PMX in severe respiratory disease patients became clear.

Increased urinary excretion of biopyrrins, oxidative metabolites of bilirubin, in patients with schizophrenia

During periods of psychological stress, excess amounts of free radicals are produced, and they play an important role in the pathophysiological process. Bilirubin oxidative metabolites, biopyrrins, are generated from bilirubin as a result of this scavenging action against free radicals. We investigated whether the urinary excretion of biopyrrin is altered during the psychotic state in patients with schizophrenia. Biopyrrin concentrations in urine of 15 patients with schizophrenia and 100 age-matched healthy subjects were measured by enzyme-linked immunosorbent assay with an anti-bilirubin antibody. Urine samples were obtained from the patients on first admission (acute state), 1 month after admission (sub-acute state), and on discharge (remission state). Urinary concentrations of biopyrrins in patients with schizophrenia on admission were significantly higher than those in the controls. Response to treatment was associated with a significant decrease in the concentrations of biopyrrins. Moreover, urinary concentrations of biopyrrins were still significantly higher in patients with schizophrenia in the sub-acute and remission states than in the controls. These results demonstrated an increase in urinary biopyrrins in patients with schizophrenia and a decrease with recovery from the psychotic state. These findings indicate that the urinary biopyrrin level is a possible indicator that can be useful in the continuous monitoring of psychotic states in clinical practice.

Urinary excretion of oxidative metabolites of bilirubin in subjects with Gilbert syndrome

BACKGROUND AND AIM

Bilirubin is a potent endogenous antioxidant substance. Recent data suggest a direct relationship exists between urinary excretion of biopyrrins, a novel group of bilirubin oxidative metabolites, and severity of oxidative stress. The aim of this study was to evaluate urinary excretion of biopyrrins in subjects with Gilbert syndrome.

METHODS

The study included patients with Gilbert syndrome (n = 33) and healthy blood donors (n = 25). In all subjects complete biochemical tests were conducted along with analysis of urinary excretion of biopyrrins. Linear and logistic regression analyses were used for multiple adjustments of possible confounders/modifiers.

RESULTS

As expected, high serum bilirubin levels were found in the Gilbert syndrome group as compared to controls (27.8 +/- 9.7 vs 9.9 +/- 3.0 micromol/L, P < 0.001). In contrast, urinary levels of biopyrrins were substantially lower in the Gilbert syndrome group as compared to normobilirubinemic control subjects (19.9 +/- 26.0 vs 90.2 +/- 139.1 U/g urinary creatinine, P < 0.001). The Gilbert syndrome group also had very low prevalence odds ratios for urinary biopyrrins above the median of the control values even after adjustment for possibly confounding factors (odds ratio 0.18, 95% confidence interval 0.33-0.94; P = 0.042).

CONCLUSIONS

An inverse relationship was demonstrated between serum bilirubin level and urinary excretion of biopyrrins, which is presumably due to antioxidative effects of elevated serum bilirubin levels in Gilbert syndrome.

Diurnal variation of biopyrrin excretion in random urine specimens is not corrected by creatinine

Circulating bilirubin is thought to function as a physiological antioxidant. One of the decomposition products of this process is the biopyrrins, which include two regioisomers: biotripyrrin-a (1,14,15,17-tetrahydro-2,7,13-trimethyl-1,14-deoxy-3-vinyl-16H-tripyrrin-8,12-dipropionic acid) and biotripyrrin-b (1,14,15,17-tetrahydro-3,7,13-trimethyl-1,14-deoxy-3-vinyl-16H-tripyrrin-8,12-dipropionic acid). We measured biopyrrins in random urine specimens and investigated whether the biopyrrin values obtained were valid when expressed as a ratio of the creatinine (Cr) concentrations. All of the random urine specimens collected over 48 hr were from presumably healthy adults. We measured the biopyrrins by means of an enzyme-linked immunosorbent assay (ELISA) using an anti-bilirubin monoclonal antibody. When the values were expressed in terms of the ratio to Cr, the within-day coefficient of variation (%CV) of the excretion of biopyrrins was reduced to 27%+/-10% (P<0.05) from 59%+/-27%. However, assay values on random or spot urine specimens were unreliable because of the large %CV. The biopyrrin concentrations only in the first-morning-urine specimens in terms of both absolute amounts and ratios to Cr significantly reflected those in a 24-hr urine specimen (P<0.001). Concentrations in a random urine specimen voided at the second collection or later did not correlate with the concentration in a 24-hr urine specimen (P>0.05), even if their values were corrected by Cr. The amounts of biopyrrins excreted in 24-hr urine specimens were significantly correlated with the 24-hr cortisol excretion (P<0.001) but not to uropepsin (P>0.05).

The Heme Catabolic Pathway and its Protective Effects on Oxidative Stress‐Mediated Diseases

Bilirubin, the principal bile pigment, is the end product of heme catabolism. For many years, bilirubin was thought to have no physiological function other than that of a waste product of heme catabolism--useless at best and toxic at worst. Although hyperbilirubinemia in neonates has been shown to be neurotoxic, studies performed during the past decade have found that bilirubin has a number of new and interesting biochemical and biological properties. In addition, there is now a strong body of evidence suggesting that bilirubin may have a beneficial role in preventing oxidative changes in a number of diseases including atherosclerosis and cancer, as well as a number of inflammatory, autoimmune, and degenerative diseases. The results also suggest that activation of the heme oxygenase and heme catabolic pathway may have beneficiary effects on disease prevention either through the action of bilirubin or in conjunction with bilirubin. If so, it may be possible to therapeutically induce heme oxygenase, increase bilirubin concentrations, and lower the risk of oxidative stress-related diseases.

Social stress increases biopyrrins, oxidative metabolites of bilirubin, in mouse urine

We investigated whether or not three kinds of social stress (isolation, crowding, and confrontation) increase urinary excretion of biopyrrins, oxidative metabolites of bilirubin, in mice. Male BALB/c mice (4 weeks old) were housed 5 per cage for 10 days. After acclimatization, mice were exposed to the above mentioned three kinds of psychosocial stress. Mouse blood and urine samples were collected after 2, 7, and 30 days of stress. Serum levels of corticosterone and urinary levels of biopyrrins were determined by EIA and ELISA, respectively. Adrenal hypertrophy, significant increases in serum concentration of corticosterone and in urinary excretion of biopyrrins were observed in mice exposed to these types of social stress for 7 days. These levels decreased after 30 days, though they were still rather high compared to the control group. These results suggested that social stress causes oxidative stress and that biopyrrins could be useful biomarkers of psychosocial stress.

Urinary excretion of biopyrrins, oxidative metabolites of bilirubin, increases in patients with psychiatric disorders

Several authors have suggested that psychological stress induces the production of reactive oxygen species (ROS). Several studies have supported the idea that bilirubin exerts antioxidative effects in vivo, and it was reported psychological stress provokes bilirubin oxidation in vivo [Yamaguchi T., Shioji I., Sugimoto A., Yamaoka M., 2002. Psychological stress increases bilirubin metabolites in human urine. Biochem. and Biophys. Res. Commun. 293, 517-520]. We investigated whether the concentration of bilirubin oxidative metabolites (biopyrrins) is increased in urine from patients with psychiatric disorders. The concentration of biopyrrins in urine of 25 patients with psychiatric disorders (schizophrenia, 15; depression, 10) was compared with 96 healthy volunteers. The concentrations of biopyrrins, as measured by enzyme-linked immunosorbent assay, were normalized to the urinary concentration of creatinine. The concentration of biopyrrins in patients with psychiatric disorders (schizophrenia and depression) was significantly higher than that of healthy volunteers. In schizophrenia, biopyrrins levels correlated with scores of the Brief Psychiatric Rating Scale (BPRS), and in depression, biopyrrins levels correlated with scores of the Hamilton Depression Rating Scale (HAM-D). These finding suggest that psychotic states are associated with an increase in the oxidative metabolites of bilirubin in human urine.

Oxidative stress and altered antioxidant defenses in children with acute exacerbation of atopic dermatitis

The underlying mechanisms of skin inflammation in atopic dermatitis (AD) are not completely understood. The purpose of the present study was to examine the involvement of oxidative stress and antioxidant defenses in children with acute exacerbation of AD. We studied 13 children who were hospitalized for acute exacerbation of AD with purulent skin infection by Staphylococcal aureus (age, 1.5 to 10.0 years), and 28 age-matched healthy subjects (controls). Urine samples obtained from the patients on admission, on 2nd and 7th-9th hospital days, as well as from the controls were analyzed for 8-hydroxy-2'-deoxyguanosine (8-OHdG) (a marker of oxidative DNA damage), acrolein-lysine adducts (a marker of lipid peroxidation), bilirubin oxidative metabolites (BOM) (a marker of antioxidant activity of bilirubin under oxidative stress) and nitrite/nitrate (NO(x)(-)) (a marker of endogenous nitric oxide production). Of these, urinary concentrations of 8-OHdG, acrolein-lysine adducts and BOM, but not NO(x)(-), were significantly higher in AD children on admission than those in control subjects. Response to treatment was associated with significant falls in the concentrations of 8-OHdG and acrolein-lysine adducts. Urinary concentrations of acrolein-lysine adducts, but not 8-OHdG, were still significantly higher in AD patients on the 7th-9th hospital day relative to the control. Urinary BOM remained almost constant and significantly high in AD children during hospitalization. Our findings indicate that oxidative stress and altered antioxidant defenses are involved in the pathophysiology of acute exacerbation of AD, and that suppression of oxidative stress might be a potentially useful strategy for the treatment of AD.

Oxidant and antioxidant activities in childhood meningitis

Animal studies have provided substantial evidence for a key role of reactive oxygen species, nitric oxide and its related compounds in the complex pathophysiology of bacterial meningitis. However, there is little information on changes in the redox status in human meningitis. In the present study, we evaluated the redox status and oxidative stress in the central nervous system of children with meningitis. Oxidant and antioxidant activities were assessed from cerebrospinal fluid levels of acrolein-lysine adducts (a marker of lipid peroxidation), nitrite (a marker of nitric oxide production) and bilirubin derivatives (a marker of antioxidant activity of bilirubin). All these markers were several times higher in children during the early phase of bacterial meningitis compared with those of children without meningitis and patients with aseptic meningitis. In the bacterial meningitis group, the levels of bilirubin derivatives correlated significantly with those of acrolein-lysine adducts and nitrite. Acrolein-lysine adducts and nitrite decreased significantly as the patients started to respond to treatment but bilirubin derivatives remained elevated. In conclusion, our data indicate the enhancement of both oxidant and antioxidant activities in the central nervous system of children with early bacterial meningitis, but not in those with aseptic meningitis. Clinical and laboratory improvement may be associated with a decrease in oxidant activities in the central nervous system.

Psychological stress increases bilirubin metabolites in human urine

Some authors have suggested that psychological stress induces the production of reactive oxygen species (ROS). Some studies have supported that bilirubin exerts anti-oxidative effects in vivo. However, it is not known whether ROS induced by psychological stress provoke bilirubin oxidation in vivo. We investigated if the concentration of bilirubin oxidative metabolite (BOM), a bilirubin oxidative metabolite, increased in urine from subjects exposed to psychological stress. Sixty healthy male volunteers working in a pharmaceutical company were divided into a Group I which did not attend a conference, a Group II which attended a conference but did not deliver a speech, and a Group III which attended a conference and delivered speeches in the presence of the company executives. Subjective stress was scored (self-rating score) after subjects in Group III delivered their speeches at the conference. Urine was collected on the next day. The BOM concentrations, as measured by enzyme-linked immunosorbent assay, were normalized to the urinary concentration of creatinine. The concentration of BOM in Group III was significantly higher compared to that in Groups I and II (p<0.01 and p<0.05, respectively). Furthermore, in Group III, the concentration of BOM correlated with the self-rating stress score (r=0.53, p<0.01). These findings suggest that emotional stimuli are associated with an increase in the oxidative metabolites of bilirubin in human urine, and that BOMs could be useful markers of psychological stress.

Urinary excretion of 8-iso-PGF(2 alpha) in three patients during sepsis, recovery and state of health

Sepsis is known to be associated with oxidative stress. Novel markers of oxidative stress are now believed to be F2-isoprostanes which are produced in situ in phospholipids and subsequently released into circulation and excreted in the urine. This study, therefore, sought to investigate whether the excretion of the isoprostane, 8-iso-PGF(2 alpha), is elevated during sepsis. The excretion of 8-iso-PGF(2 alpha), in the 24 h urine of three patients was studied in the septic stage, during mobilisation and in the state of health by a radioimmunological method. Extrapolating the urinary excretion of 8-iso-PGF(2 alpha) over time showed an insignificant variation in the excretion values during 24 h. The amount of mean 24 h urinary 8-iso-PGF(2 alpha) was about similar in the septic stage and in the state of health but increased remarkably during mobilisation in two of the patients. We suggest that mobilisation of septic patients can be associated with an increase of oxidative stress which may stem from an increase in oxygen consumption and/or from a depletion of antioxidants leading to the enhanced formation of free radicals.