Plasma Total Bilirubin Concentration Research Articles

The effect of dietary rumen-protected trans-10,cis-12 conjugated linoleic acid or a milk fat-depressing diet on energy metabolism, inflammation, and oxidative stress of dairy cows in early lactation

The objective of this study was to determine the effects of milk fat depression induced by supplementing conjugated linoleic acid (CLA; trans-10,cis-12 and cis-9,trans-11 CLA) or feeding a higher starch and oil-containing diet (HSO) on metabolic changes in dairy cows after calving. The main hypothesis was that the 2 strategies to decrease milk fat yield could have different effects on performance, energy balance (EB), and inflammatory status in early lactation. Thirty-three Nordic Red dairy cows were used in a randomized block design from 1 to 112 d of lactation and fed one of the following treatments: control (CON), CLA-supplemented diet, or HSO diet. Dry matter intake and milk yield were measured daily whereas milk composition was measured weekly throughout the experiment. Nutrient digestibility, EB, and plasma hormones and metabolites were measured at 3, 7, 11, and 15 wk of lactation in respiration chambers. The HSO diet led to lower intakes of dry matter, neutral detergent fiber, and gross energy compared with CON and CLA diets. The CLA diet and especially the HSO diet resulted in lower energy-corrected milk yield during the first 7 wk of lactation than those fed CON. The EB was numerically higher for HSO and CLA diets compared with CON at wk 3 and 7. Plasma glucose concentration was higher by the CLA diet at wk 3 and by the HSO diet from wk 3 to 15 compared with CON. Plasma nonesterified fatty acids were higher at wk 3 in the CON group (indicating more lipid mobilization) but decreased thereafter to similar levels with the other groups. The HSO-fed cows had higher plasma ceruloplasmin, paraoxonase, and total bilirubin concentrations in the entire experiment and showed the highest levels of reactive oxygen metabolites. These results suggest an increased inflammatory and oxidative stress state in the HSO cows and probably different regulation of the innate immune system. This study provides evidence that milk fat depression induced by feeding HSO (as well as CLA) decreased milk fat secretion and improved EB compared with CON in early lactation. The increase in plasma glucose and paraoxonase levels with the HSO diet may imply a better ability of the liver to cope with the metabolic demand after parturition. However, the negative effect of HSO on feed intake, and the indication of increased inflammatory and oxidative stress warrant further studies before the HSO feeding strategy could be supported as an alternative to improve EB in early lactation.

Cardiomyopathy in patients with type 1 tyrosinemia, and the effect of nitisinone treatment on cardiomyopathy

Purpose: This study aimed to retrospectively evaluate the frequency of cardiomyopathy and its response to routinely used nitisinone treatment in patients with tyrosinemia type 1.
 Materials and Methods: Participants of this descriptive cross-sectional study were Tyrosinemia Type 1 patients who were under the care of a single metabolic unit. The primary outcome of the study was “presence of abnormal echocardiographic findings” at diagnosis and the impact of nitisinone treatment on the detected findings.
 Results: Of the 54 patients enrolled in the study, 21 (38.9%) were female and 33 (61.1%) were male. 41 patients were evaluated using echocardiography at the time of diagnosis. 9 (21.9%) of them had hypertrophic cardiomyopathic alterations varying in severity. In the follow-up period, second echocardiographic examinations revealed improvements in cardiac alterations while on nitisinone treatment. Thirteen patients dropped out of follow-up. Of the remaining 41 patients, 10 (24.4%) patients died in the follow-up period, whereas 31 (75.6%) remained alive. Plasma aspartate aminotransferase (AST), total bilirubin, and direct bilirubin concentrations were significantly higher in patients witj normal cardiac evaluation.
 Conclusion: Echocardiographic examination should be done in all tyrosinemia type 1 patients including those with an absence of cardiac manifestations. The presence of cardiomyopathy may indicate a poor prognosis. Nitisinone is found to have a positive impact on cardiomyopathy in patients with type 1 tyrosinemia.

Protective effect of aqueous leaf extracts of Chromolaena odorata and Tridax procumbens on doxorubicin-induced hepatotoxicity in Wistar rats.

Background:The liver is one of the organs affected by doxorubicin toxicity. Therefore, in this study, the potential protective role of aqueous leaf extracts of Chromolaena odorata and Tridax procumbens against doxorubicin-induced hepatotoxicity was investigated.Methods:In order to achieve this, their impact on hepatic biomarkers of oxidative stress, lipid and electrolytes’ profile, and plasma biomarkers of liver functions/integrity were monitored in doxorubicin treated rats. The animals were treated with either metformin (250 mg/kg body weight orally for 14 days) or the extracts (50, 75, and 100 mg/kg orally for 14 days) and/or doxorubicin (15 mg/kg, intraperitoneal, 48 h before sacrifice).Results:The hepatic malondialdehyde, cholesterol, calcium, and sodium concentrations, and plasma activities of alanine and aspartate transaminases and alkaline phosphatase, as well as plasma albumin to globulin ratio of test control were significantly (P < .05) higher than those of all the other groups. However, the plasma albumin, total protein, globulin, and total bilirubin concentrations; hepatic concentrations of ascorbic acid, chloride, magnesium, and potassium; and hepatic activities of catalase, glutathione peroxidase, and superoxide dismutase of test control were significantly (P < .05) lower than those of all the other groups.Conclusions:Pretreatment with the extracts and metformin prevented to varying degrees, doxorubicin-induced hepatic damage, as indicated by the attenuation of doxorubicin-induced adverse alterations in hepatic biomarkers of oxidative stress, lipid and electrolyte profiles, and plasma biomarkers of hepatic function/integrity, and keeping them at near-normal values.

Investigation of Risk Factors Related to the Development of Hepatic Dysfunction in Patients with a Low and Moderate Cardiac Risk During Open-Heart Surgeries.

ObjectiveTo determine the possible risk factors associated with hepatic dysfunction during open-heart surgeries.MethodsAfter excluding 71 patients, 307 patients with possible low and moderate cardiac risk who underwent either coronary artery bypass graft surgery (CABG) (n=176) or valve repair surgery (mitral valve, mitral and aortic valves and/or tricuspid valve) (n=131) were investigated prospectively during a 6-month period. Hyperbilirubinemia is defined as an occurrence of a plasma total bilirubin concentration >34 µmol/L (2 mg/dL) in any measurement during the postoperative period; the patients were divided into groups with or without postoperative hyperbilirubinemia. The collected parameters were: alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP), total bilirubin (TBil), gamma-glutamyl transpeptidase (GGT) and albumin. The parameters were collected preoperatively and postoperatively on days 1, 3 and 7. Preoperative, intraoperative, and postoperative risk factors were investigated. Logistic regression analysis was performed to identify the risk factors for postoperative hyperbilirubinemia.ResultsPostoperative hyperbilirubinemia was observed in 7 of 176 patients (4%) who underwent CABG, and in 11 of 131 patients (8.4%) who underwent valve replacement surgeries. Independent risk factors for early postoperative hyperbilirubinemia were found as: ejection fraction (EF), aortic cross-clamp (ACC) time, intensive care unit stay and extubation time (P<0.001). In comparison to CABG procedures, postoperative hyperbilirubinemia was observed more frequently in patients undergoing valve surgeries (P=0.027).ConclusionLow EF and prolonged ACC time are significant independent risk factors for early postoperative hyperbilirubinemia during open-heart surgeries with cardiopulmonary bypass. Valve surgeries show a higher incidence of hyperbilirubinemia in comparison to CABG.

Dietary squalene supplementation alleviates diquat-induced oxidative stress and liver damage of broiler chickens

The aim of this study was to explore the protective effects of squalene supplementation on growth performance, oxidative status, and liver function of diquat-challenged broilers. One hundred forty-four 1-day-old male Ross 308 broiler chicks were allocated to 3 groups, and each group consisted of 6 replicates of 8 birds each. The three groups were as follows: 1) nonchallenged broilers fed with a basal diet (control group), 2) diquat-challenged broilers fed a basal diet, and 3) diquat-challenged broilers fed with a basal diet supplemented with 1.0 g/kg of squalene. Broilers were intraperitoneally injected with 20 mg/mL of diquat solution at a dosage of 1 mL/kg of BW or an equivalent amount of saline at 20 d. Compared with the control group, weight gain and BW change rate during 24 h after injection were decreased by diquat challenge (P < 0.05), and the diquat-induced compromised growth performance was improved by squalene supplementation (P < 0.05). Diquat administration reduced plasma superoxide dismutase activity and increased malondialdehyde accumulation and glutathione peroxidase activity in both plasma and the liver (P < 0.05). In contrast, plasma glutathione peroxidase activity in diquat-challenged broilers was reduced by squalene supplementation (P < 0.05). The hepatic glutathione level was reduced by diquat administration (P < 0.05), whereas its level in plasma and the liver of diquat-challenged broilers was increased by squalene supplementation (P < 0.05). The relative liver weight of broilers was increased by diquat challenge (P < 0.05), with its value being intermediate in the squalene-supplemented group (P > 0.05). The plasma aminotransferase activities and total bilirubin concentration were increased by diquat challenge (P < 0.05), which were reduced by squalene supplementation (P < 0.05). The mRNA abundance of hepatic nuclear factor erythroid 2–related factor 2 (P < 0.05) was upregulated by diquat treatment, regardless of squalene supplementation. The mRNA abundance of hepatic glutathione peroxidase 1 and B-cell lymphoma/leukemia 2–associated X protein was upregulated by diquat challenge (P < 0.05), which was reversed by squalene administration (P < 0.05). Squalene increased NAD(P)H quinone dehydrogenase 1 mRNA abundance and decreased caspase 3 mRNA abundance in the liver of diquat-challenged broilers (P < 0.05). The results suggested that squalene can increase weight gain, improve oxidative status, and alleviate liver injury in diquat-challenged broilers.

Blood parameters in fattening pigs from two genetic types fed diet with three different protein concentrations.

The study aimed to evaluate possible differences between two genetic groups (GG) of pigs, fed diets varying in dietary CP level, in hematological and biochemical plasma profiles. The study was carried out in an experimental farm and involved 36 barrows (average BW 129 ± 11 kg) from two GG: group A (18 Italian Duroc boars × Italian Large White sows) and group D (18 DanBred Duroc), fed three experimental diets: a conventional diet and two low-protein diets (LP1 and LP2). A digestibility/balances trial was carried out on 12 pigs A and 12 pigs D that were housed individually in metabolic cages during four digestibility/balances periods. The experimental design was a factorial design, with 3 diets × 2 GG × 4 periods. The experiment lasted 56 d. Blood was sampled from jugular vein in the morning before feed distribution from all barrows in pens at the start and the end of the experimental period; a supplementary blood sample was collected from the 24 pigs at the end of the four digestibility periods (six pigs per period). Blood was analyzed for hematological and biochemical parameters and serum protein profile using automated analyzers. The GG D showed lower white blood cells (WBC), lymphocyte, and monocyte counts than A group. The GG affected several plasma metabolite concentrations: triglycerides, creatinine, Cl, Fe, alkaline phosphatase, and tartrate-resistant acid phosphatase activities were higher in D groups, while urea, albumin, Ca, Na, total bilirubin, and albumin as percentage of total protein were lower than A group. On the contrary, the dietary protein level neither affects WBC nor their populations; only a trend was reported for erythrocytes (red blood cell) and platelets. The diet affected only plasma urea and total bilirubin concentrations.

Evaluation of potential predictor variables for PCR assay diagnosis of Anaplasma phagocytophilum infection in equids in Northern California.

OBJECTIVE To identify clinical or clinicopathologic variables that can be used to predict a positive PCR assay result for Anaplasma phagocytophilum infection in equids. ANIMALS 162 equids. PROCEDURES Medical records were reviewed to identify equids that underwent testing for evidence of A phagocytophilum infection by PCR assay between June 1, 2007, and December 31, 2015. For each equid that tested positive (case equid), 2 time-matched equids that tested negative for the organism (control equids) were identified. Data collected included age, sex, breed, geographic location (residence at the time of testing), physical examination findings, and CBC and plasma biochemical analysis results. Potential predictor variables were analyzed by stepwise logistic regression followed by classification and regression tree analysis. Generalized additive models were used to evaluate identified predictors of a positive test result for A phagocytophilum. RESULTS Total lymphocyte count, plasma total bilirubin concentration, plasma sodium concentration, and geographic latitude were linear predictors of a positive PCR assay result for A phagocytophilum. Plasma creatine kinase activity was a nonlinear predictor of a positive result. CONCLUSIONS AND CLINICAL RELEVANCE Assessment of predictors identified in this study may help veterinarians identify equids that could benefit from early treatment for anaplasmosis while definitive test results are pending. This information may also help to prevent unnecessary administration of oxytetracycline to equids that are unlikely to test positive for the disease.

Mutation responsible for congenital photosensitivity and hyperbilirubinemia in Southdown sheep.

OBJECTIVE To identify the genetic cause for congenital photosensitivity and hyperbilirubinemia (CPH) in Southdown sheep. ANIMALS 73 Southdown sheep from a CPH research flock and 48 sheep of various breeds from commercial flocks without CPH. PROCEDURES Whole-genome sequencing was performed for a phenotypically normal Southdown sheep heterozygous for CPH. Heterozygous variants within Slco1b3 coding exons were identified, and exons that contained candidate mutations were amplified by PCR assay methods for Sanger sequencing. Blood samples from the other 72 Southdown sheep of the CPH research flock were used to determine plasma direct and indirect bilirubin concentrations. Southdown sheep with a plasma total bilirubin concentration < 0.3 mg/dL were classified as controls, and those with a total bilirubin concentration ≥ 0.3 mg/dL and signs of photosensitivity were classified as mutants. Sanger sequencing was used to determine the Slco1b3 genotype for all sheep. Genotypes were compared between mutants and controls of the CPH research flock and among all sheep. Protein homology was measured across 8 species to detect evolutionary conservation of Slco1b. RESULTS A nonsynonymous mutation at ovine Chr3:193,691,195, which generated a glycine-to-arginine amino acid change within the predicted Slco1b3 protein, was significantly associated with hyperbilirubinemia and predicted to be deleterious. That amino acid was conserved across 7 other mammalian species. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested a nonsynonymous mutation in Slco1b3 causes CPH in Southdown sheep. This disease appears to be similar to Rotor syndrome in humans. Sheep with CPH might be useful animals for Rotor syndrome research.

The Bilirubin Binding Panel: A Henderson-Hasselbalch Approach to Neonatal Hyperbilirubinemia.

Poor plasma bilirubin binding increases the risk of bilirubin neurotoxicity in newborns with hyperbilirubinemia. New laboratory tests may soon make it possible to obtain a complete bilirubin binding panel when evaluating these babies. The 3 measured components of the panel are the plasma total bilirubin concentration (BTotal), which is currently used to guide clinical care; the bilirubin binding capacity (BBC); and the concentration of non-albumin bound or free bilirubin (BFree). The fourth component is the bilirubin-albumin equilibrium dissociation constant, KD, which is calculated from BTotal, BBC, and BFree The bilirubin binding panel is comparable to the panel of components used in the Henderson-Hasselbalch approach to acid-base assessment. Bilirubin binding population parameters (not prospective studies to determine whether the new bilirubin binding panel components are better predictors of bilirubin neurotoxicity than BTotal) are needed to expedite the clinical use of bilirubin binding. At any BTotal, the BFree and the relative risk of bilirubin neurotoxicity increase as the KD/BBC ratio increases (ie, bilirubin binding worsens). Comparing the KD/BBC ratio of newborns with BTotal of concern with that typical for the population helps determine whether the risk of bilirubin neurotoxicity varies significantly from the inherent risk at that BTotal Furthermore, the bilirubin binding panel individualizes care because it helps to determine how aggressive intervention should be at any BTotal, irrespective of whether it is above or below established BTotal guidelines. The bilirubin binding panel may reduce anxiety, costs, unnecessary treatment, and the likelihood of undetected bilirubin neurotoxicity.

Supplementation with l-arginine stabilizes plasma arginine and nitric oxide metabolites, suppresses elevated liver enzymes and peroxidation in sickle cell anaemia

The effect of l-arginine on liver function in SCD has received little or no attention. The effect of a chronic, oral, low-dose supplementation with l-arginine (1gm/day for 6 weeks) on some liver enzymes, lipid peroxidation and nitric oxide metabolites was studied in 20 normal (non-sickle cell anaemia; NSCA) subjects and 20 sickle cell anaemia (SCA) subjects. Ten milliliters of blood was withdrawn from an ante-cubital vein for the estimation of plasma arginine concentration ([R]), alanine aminotransaminase (ALT), aspartate aminotransaminase (AST) and alkaline phosphatase (ALP), plasma total bilirubin concentration [TB], malondialdehyde concentration [MDA] and nitric oxide metabolites concentration [NOx]. Before supplementation, ALT, AST, ALP (p<0.05 respectively) and TB (p<0.001) were higher in SCA subjects than in NSCA subjects. [R] and [NOx] were higher in NSCA subjects (p<0.001 and p<0.05 respectively). Supplementation caused greater percent increases in [R], and [NOX] in SCA than in NSCA subjects (p<0.001 in each case). l-Arginine caused greater percent reductions in ALT and AST in SCA subjects but greater percent reduction in ALP in NSCA subjects (p<0.001 in each case). Changes in [MDA] and [TB] in the two groups were similar. Study shows that chronic, oral, low-dose supplementation with l-arginine improved liver function, oxidative stress, plasma arginine concentration and nitric oxide metabolites levels in NSCA and SCA subjects. Responses in SCA subjects to l-arginine were more sensitive than in NSCA subjects.

Atorvastatin treatment increases plasma bilirubin but not HMOX1 expression in stable angina patients

Background. In vitro and animal studies indicate that statins increase heme oxygenase-1 gene (HMOX1) expression, which then, presumably, increases plasma bilirubin concentration. However, clinical confirmation that statins concomitantly increase HMOX1 expression and plasma bilirubin concentration is lacking. We hypothesized that in patients with stable angina atorvastatin therapy (20 mg/day for 10 weeks) concomitantly increases total bilirubin concentration and HMOX1 expression, as assessed non-invasively by plasma analysis. Methods. In 44 patients with stable angina plasma concentrations of total bilirubin, HMOX1 mRNA and HMOX1 protein were measured before and after the statin treatment, as well as plasma concentrations of oxidized low-density lipoprotein (OxLDL), malondialdehyde (MDA), monocyte chemoattractant protein (MCP-1) and C-reactive protein (CRP). Results. Atorvastatin treatment increased total bilirubin concentration (median 6.95 μmol/L vs. 8.55, + 23.02%; p < 0.001), but did not change plasma HMOX1 mRNA and HMOX1 protein concentrations. Plasma concentrations of OxLDL (− 31.85%, p < 0.001), MCP-1 (− 16.20%, p = 0.020) and CRP (− 7.32%, p = 0.010) were decreased but MDA was not decreased (15.32%, p = 0.107). Within subjects, increment of plasma bilirubin concentration did not correlate with the changes in HMOX1 mRNA and protein concentrations, but correlated with low-density lipoprotein cholesterol decrement (r = − 0.374, p = 0.012). Bilirubin increment did not correlate with the changes in oxidative and inflammatory markers. Conclusion. Our prospective observational trial finally confirms that atorvastatin (20 mg/day for 10 weeks) increases plasma total bilirubin concentration. However, it seems that this effect is HMOX1-independent.

Haemato-Biochemical and Oxidative Responses of Adult Wistar Rats to Methanolic Extracts of Abrus precatorius Linn Leaves

In the present study, we explored the hematological, biochemical and oxidative chanes caused by the administration of 70% methanolic leaf extracts of A. precatorius to adult wistar rats in sub-acute and sub chronic study of 28 and 90 days respectively. Treatment with varying doses of the extract caused a significant increase in red blood cell counts and packed cell volume when compared to the control values. The biochemical parameters studied at the end of the 28-day treatment varied within the control range, however, following the 90-day treatment the parameters showed significant upward derangement, especially serum alanine aminotransferase, aspartate aminotransferase, mean plasma total bilirubin concentrations and mean plasma conjugated bilirubin concentrations, indicative of organ injury. The extract at all doses provided significant protection against hepatic lipid peroxidation and increased antioxidant enzyme activities such as superoxide dismutase, catalase, and glutathione peroxidase. In conclusion, the extract had positive haematopoietic property but should not be taken for a long time due to its effect on the liver enzymes. Also the extract has shown potential as an antioxidant and thus may be useful in the prevention of diseases caused by oxidative stress.

Substantial Effect of Efavirenz Monotherapy on Bilirubin Levels in Healthy Volunteers

BackgroundEfavirenz exhibits multiple interactions with drug-metabolizing enzymes and transporters, and for this reason efavirenz-based HIV therapy is associated with altered pharmacokinetics of coadministered drugs. Probably by the same mechanism, efavirenz-based HIV therapy affects the disposition of endogenous compounds, but this effect is difficult to directly link with efavirenz because it is used in combination with other drugs. ObjectivesTo explore the effect of efavirenz monotherapy on biochemical laboratory values in a clinical trial of healthy volunteers. MethodsMen and women (aged 18–49 years) with body mass index ≤32 who were assessed to be healthy based on medical history, physical examination, and standard laboratory screening received a single (600 mg) and multiple doses (600 mg/d for 17 days) of efavirenz orally. This trial was designed to determine the pharmacokinetics and drug interactions of efavirenz. As part of this study, analysis of serum chemistries that were measured at study entry (screening) and 1 week after completion of the multiple dose study (exit) is reported. ResultsData from 60 subjects who fully completed and 13 subjects who partially completed the study are presented. Total bilirubin was substantially reduced at exit (by ~30%, with large intersubject variability) compared with screening values (P < 0.0001). The percent changes were in part explained by the intersubject differences in baseline total bilirubin because there was a significant correlation between baseline (screening) values and percent change at exit (r = 0.50; P < 0.0001). Hemoglobin and absolute neutropenia were also substantially decreased at exit compared with screening, but this may be due to intensive blood sampling rather than direct effect of efavirenz on these parameters. No significant correlation was found between percent change in hemoglobin versus percent change in bilirubin, indicating the effect of efavirenz on bilirubin is independent of its effects on hemoglobin. ConclusionsEfavirenz monotherapy significantly lowers plasma total bilirubin concentration in healthy volunteers independent of its effect on hemoglobin, probably through its effects on bilirubin metabolism and transport (uptake and efflux). These findings help explain reversal by efavirenz of hyperbilirubinemia induction observed by some protease inhibitor antiretroviral drugs (eg, atazanavir). Besides its well-documented role on drug interactions, efavirenz may alter the disposition of endogenous compounds relevant in physiologic homeostasis through its interaction with drug metabolizing enzymes and/or drug transporters. ClinicalTrials.gov identifier: NCT00668395.

Hepatoprotective, Antioxidant, and Ameliorative Effects of Ginger (Zingiber officinale Roscoe) and Vitamin E in Acetaminophen Treated Rats

ABSTRACTGinger is a remedy known to possess a number of pharmacological properties. This study investigated efficacy of ginger pretreatment in alleviating acetaminophen-induced acute hepatotoxicity in rats. Rats were divided into six groups; negative control, acetaminophen (APAP) (600 mg/kg single intraperitoneal injection); vitamin E (75 mg/kg), ginger (100 mg/kg), vitamin E + APAP, and ginger + APAP. Administration of APAP elicited significant liver injury that was manifested by remarkable increase in plasma alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), arginase activities, and total bilirubin concentration. Meanwhile, APAP significantly decreased plasma total proteins and albumin levels. APAP administration resulted in substantial increase in each of plasma triacylglycerols (TAGs), malondialdhyde (MDA) levels, and total antioxidant capacity (TAC). However, ginger or vitamin E treatment prior to APAP showed significant hepatoprotective effect by lowering the hepatic marker enzymes (AST, ALT, ALP, and arginase) and total bilirubin in plasma. In addition, they remarkably ameliorated the APAP-induced oxidative stress by inhibiting lipid peroxidation (MDA). Pretreatment by ginger or vitamin E significantly restored TAGs, and total protein levels. Histopathological examination of APAP treated rats showed alterations in normal hepatic histoarchitecture, with necrosis and vacuolization of cells. These alterations were substantially decreased by ginger or vitamin E. Our results demonstrated that ginger can prevent hepatic injuries, alleviating oxidative stress in a manner comparable to that of vitamin E. Combination therapy of ginger and APAP is recommended especially in cases with hepatic disorders or when high doses of APAP are required.

Bilirubin Binding Contributes to the Increase in Total Bilirubin Concentration in Newborns With Jaundice

This study tests the hypothesis that the hourly rate of increase in plasma bilirubin concentration (DeltaBT) would increase significantly with increasing binding avidity. The plasma total bilirubin concentration (B(T)), unbound bilirubin concentration, and albumin concentration values for healthy newborns with jaundice (<or=100 hours of age, >or=35 weeks of gestation, and >or=2.5 kg at birth) were obtained from medical records. DeltaBT (in milligrams per deciliter per hour) was calculated as the slope of BT versus age (in hours). Binding avidity was quantified as the product of the albumin concentration and its bilirubin binding constant (K). Linear correlation was used to test the hypothesis that DeltaBT would increase significantly with K.albumin concentration. The ranges of BT, unbound bilirubin concentration, albumin concentration, and K values for the 21 patients studied were 7.6 to 28.5 mg/dL, 0.53 to 2.52 microg/dL, 2.9 to 4.6 g/dL, and 38 to 163 L/micromol, respectively. DeltaBT correlated significantly with K.albumin concentration (r2=0.23; P=.026). Plasma bilirubin binding avidity contributes significantly to DeltaBT. This component of DeltaBT is associated with a lower risk of bilirubin neurotoxicity, and studies aimed at incorporating plasma bilirubin binding avidity measurements into the algorithms used for management of newborn jaundice seem warranted.

Unbound (Free) Bilirubin: Improving the Paradigm for Evaluating Neonatal Jaundice

The serum or plasma total bilirubin concentration (B(T)) has long been the standard clinical laboratory test for evaluating neonatal jaundice, despite studies showing that B(T) correlates poorly with acute bilirubin encephalopathy (ABE) and its sequelae including death, classical kernicterus, or bilirubin-induced neurological dysfunction (BIND). The poor correlation between B(T) and ABE is commonly attributed to the confounding effects of comorbidities such as hemolytic diseases, prematurity, asphyxia, or infection. Mounting evidence suggests, however, that B(T) inherently performs poorly because it is the plasma non-protein-bound (unbound or free) bilirubin concentration (B(f)), rather than B(T), that is more closely associated with central nervous system bilirubin concentrations and therefore ABE and its sequelae. This article reviews (a) the complex relationship between serum or plasma bilirubin measurements and ABE, (b) the history underlying the limited use of B(f) in the clinical setting, (c) the peroxidase method for measuring B(f) and technical and other issues involved in adapting the measurement to routine clinical use, (d) clinical experience using B(f) in the management of newborn jaundice, and (e) the value of B(f) measurements in research investigating bilirubin pathochemistry. Increasing evidence from clinical studies, clinical experience, and basic research investigating bilirubin neurotoxicity supports efforts to incorporate B(f) expeditiously into the routine evaluation of newborn jaundice.

Unbound bilirubin predicts abnormal automated auditory brainstem response in a diverse newborn population

The objective of this study was to determine if plasma unbound or 'free' bilirubin concentration (B(f)) measured during the first 30 days of life is associated with subsequent abnormal hearing screening testing by automated auditory brainstem response (AABR) in a diverse population of newborns. An observational study of newborns receiving AABR, plasma total bilirubin concentration (TBC) and B(f) measurements and without underlying conditions known to affect hearing was conducted. Logistic regression was used to determine associations between abnormal AABR and B(f) or TBC. The impacts of a variety of clinical factors on the regression model were also assessed. A total of 191 patients with birth weights and gestations ranging from 406 to 4727 g and 24 to 42 weeks, respectively, were studied. Among them, 175 (92%) had normal (bilateral PASS) AABR and 16 had abnormal AABR (6 had unilateral REFER AABR, and 10 had bilateral REFER AABR). Mean TBC was not significantly different in babies with normal or abnormal AABR, but mean B(f) was greater in the latter group (1.76 versus 0.93 microg per 100 ml, respectively, P=0.012). B(f), but not TBC, was associated with an abnormal AABR (B(f) adjusted odds ratio 3.3, 95% CI 1.8 to 6.1). Comparing receiver-operating characteristics curves, the B(f)/TBC ratio was a better predictor of an abnormal AABR than B(f) alone. Intraventricular hemorrhage was the only confounding clinical variable. An abnormal AABR is associated with an elevated B(f) or B(f)/TBC ratio, but not the TBC alone. The prevalence of bilirubin neurotoxicity as a cause of audiological dysfunction may be underestimated if the TBC alone is used to assess the severity of newborn jaundice.

Visual screening versus transcutaneous bilirubinometry for predischarge jaundice assessment

Comparison of visual screening with transcutaneous bilirubinometry (TcB) in identifying neonates with plasma total bilirubin (PTB) > or =75th percentile. In 100 paired readings PTB was 34 +/- 24 micromol/L higher than the TcB counterpart. A TcB reading of 154 micromol/L was therefore regarded as equivalent to a PTB of 188 micromol/L, corresponding to the 75th percentile at 48 h. Predischarge, all newborns were evaluated for jaundice, first by visual inspection and then transcutaneously. PTB was ordered as indicated by visual assessment or if the TcB reading was > or =154 micromol/L. Of 346 newborns tested, 25 (7.2%) had a PTB concentration > or =75th percentile. Forty-nine had PTB determinations based on TcB compared with 83 by visual assessment. However, a similar number of affected newborns was identified by each method (21/25 (84%) by visual screening vs. 18/25 (72%) by TcB). PTB concentrations of those who had been chosen by TcB were higher than those selected visually (202 +/- 24 micromol/L vs. 186 +/- 31 micromol/L). A practical method for predischarge detection of neonates with plasma total bilirubin concentration > or = 75th percentile, implementing transcutaneous bilirubinometry, is described. The transcutaneous technique required fewer blood tests than visual assessment for similar yield.

Unbound Bilirubin Concentration is Associated With Abnormal Automated Auditory Brainstem Response for Jaundiced Newborns

This study was conducted to determine whether incidental jaundice affects automated auditory brainstem response results. We reviewed the medical charts of jaundiced newborns of > or = 34 weeks of gestation who underwent automated auditory brainstem response testing within 4 hours of plasma total bilirubin concentration and unbound bilirubin concentration measurements. We tested the hypothesis that the likelihood of abnormal automated auditory brainstem response results would increase as total bilirubin and unbound bilirubin concentrations increased. Forty-four infants with proximate total bilirubin concentration, unbound bilirubin concentration, and automated auditory brainstem response measurements were identified, and 4 (9%) had bilateral refer automated auditory brainstem response results. The mean total bilirubin concentration of 21.4 mg/dL (SD: 4.0 mg/dL; range: 14.4-29.5 mg/dL) for the 40 infants with bilateral pass automated auditory brainstem response results was not significantly different from that of 23.0 mg/dL (range: 14.9-33.1 mg/dL) for the 4 infants with bilateral refer automated auditory brainstem response results. However, the mean unbound bilirubin concentration of 1.32 microg/dL (range: 0.22-2.99 microg/dL) for the 40 infants with bilateral pass results was significantly lower than the mean of 2.62 microg/dL (range: 0.88-4.41 microg/dL) for the 4 infants with bilateral refer results. Logistic regression showed that increasing unbound bilirubin concentrations but not increasing total bilirubin concentrations were associated with of bilateral refer automated auditory brainstem response results. The probability of bilateral refer automated auditory brainstem response results increases significantly with increasing unbound bilirubin concentrations but not with increasing total bilirubin concentrations. Because unbound bilirubin concentrations are also more closely correlated with bilirubin neurotoxicity than are total bilirubin concentrations, bilateral refer automated auditory brainstem response results for jaundiced newborns may indicate increased risk of bilirubin neurotoxicity, in addition to the possibility of congenital deafness.

Changes in markers of muscle damage, inflammation and HSP70 after an Ironman triathlon race

We investigated the effects of an Ironman triathlon race on markers of muscle damage, inflammation and heat shock protein 70 (HSP70). Nine well-trained male triathletes (mean +/- SD age 34 +/- 5 years; VO(2peak) 66.4 ml kg(-1) min(-1)) participated in the 2004 Western Australia Ironman triathlon race (3.8 km swim, 180 km cycle, 42.2 km run). We assessed jump height, muscle strength and soreness, and collected venous blood samples 2 days before the race, within 30 min and 14-20 h after the race. Plasma samples were analysed for muscle proteins, acute phase proteins, cytokines, heat shock protein 70 (HSP70), and clinical biochemical variables related to dehydration, haemolysis, liver and renal functions. Muscular strength and jump height decreased significantly (P < 0.05) after the race, whereas muscle soreness and the plasma concentrations of muscle proteins increased. The cytokines interleukin (IL)-1 receptor antagonist, IL-6 and IL-10, and HSP70 increased markedly after the race, while IL-12p40 and granulocyte colony-stimulating factor (G-CSF) were also elevated. IL-4, IL-1beta and tumour necrosis factor-alpha did not change significantly, despite elevated C-reactive protein and serum amyloid protein A on the day after the race. Plasma creatinine, uric acid and total bilirubin concentrations and gamma-glutamyl transferase activity also changed after the race. In conclusion, despite evidence of muscle damage and an acute phase response after the race, the pro-inflammatory cytokine response was minimal and anti-inflammatory cytokines were induced. HSP70 is released into the circulation as a function of exercise duration.