Levitt's CO breath test in the differential diagnosis of chronic isolated hyperbilirubinemia.

A key component of the differential diagnosis of isolated hyperbilirubinemia (HB) is distinguishing between hemolytic and non-hemolytic types. Routine hemolysis screening markers have unsatisfactory sensitivity and specificity. Erythrocyte (RBC) lifespan shortening, the gold standard marker of hemolysis, is seldomly measured due to the cumbersome and protracted nature of standard methods. A new Levitt's CO breath test method may enable simple, rapid RBC lifespan measurement. In this pilot prospective diagnostic study, Levitt's CO breath test was evaluated to discriminate hemolytic from non-hemolytic HB in adults. One hundred and thirty eligible non-smoking adult patients who were aged 18 or older, referred for chronic (>6 months) isolated HB or had a known diagnosis of isolated HB of a rare cause, were recruited, including 77 with non-hemolytic HB and 53 with hemolytic HB. ROC curve analysis was applied to determine the optimal cutoff for discriminating between hemolytic and non-hemolytic HB, and the performance was calculated. Results showed that the mean RBC lifespan in non-hemolytic HB (93 ± 26 d) was reduced (p= 0.001 vs. normal reference value of 126 d), but longer than that in hemolytic HB (36 ± 17 d;p= 0.001). RBC lifespans did not differ significantly between 26 patients with simple hemolytic HB (32 ± 14 d) and 27 patients with a Gilbert syndrome comorbidity (40 ± 18 d). ROC curve analysis revealed an optimal lifespan cutoff for discriminating between hemolytic and non-hemolytic HB of 60 d (AUC = 0.982), with a diagnostic accuracy of 95.4%, 94.3% sensitivity and 96.1% specificity respectively. These results indicate that Levitt's CO breath test seems to be very sensitive and specific for detecting hemolysis in adult patients with chronic isolated HB, and could enable simple, rapid, and reliable differential diagnosis of isolated HB. A large-scale validation study of the method is warranted.

Hemodiafiltration improves red blood cell lifespan in patients with end-stage renal disease.

INTRODUCTION: Uremic toxin-induced shortening of red blood cell (RBC) lifespan is an important mechanism of anemia in end-stage renal disease (ESRD). Conventional hemodialysis does not improve RBC lifespan; the efficacy of hemodiafiltration (HDF) for alleviating RBC lifespan has not yet been evaluated in patients with ESRD. METHODS: Twenty-three patients with ESRD in maintenance hemodialysis were enrolled. Baseline data for sex, age, dialysis vintage, pre-dialysis hemoglobin (Hb), blood urea nitrogen (BUN), intact parathyroid hormone (iPTH), single pool Kt/V (spKt/V), and plasma indophenol sulfate (IS) were collected. RBC lifespans before and after one session of HDF were compared. The resultant differences were subjected to correlational analyses with baseline data. RESULTS: RBC lifespan increased from 73 (66, 89) days at baseline to 77 (71, 102) days after a single HDF treatment (p = 0.034). Meanwhile, plasma IS concentration decreased from 113.05 (80.67, 133.05) mg/L to 83.87 (62.98, 96.78) mg/L (p < 0.001). RBC lifespan increases correlated negatively with Hb levels. CONCLUSIONS: A single HDF treatment improved RBC lifespan in ESRD patients on maintenance hemodialysis, with more severe pre-HDF anemia at baseline being associated with greater increases in RBC lifespan.

Possible two-photon absorption in the near-infrared region observed by cavity ring-down spectroscopy.

Two-photon absorption spectra are difficult to observe using direct absorption spectroscopy especially in the near-infrared region. Cavity ring-down spectroscopy is a promising absorption spectroscopy technique which has been widely applied to linear and saturated single-photon absorption spectra. In the present study, we report the observation of a possible two-photon absorption in the near-infrared using cavity ring-down spectroscopy, namely a two-photon resonance of methane. Using an optical frequency comb, the single-photon wavenumber of the double-quantum transition has been determined to be 182 207 682.645 MHz with a standard deviation of 75 kHz.

A pilot study: effect of erythrocyte lifespan determined by a modified carbon monoxide breath test on glycosylated hemoglobin interpretation.

Glycosylated hemoglobin (HbA1c) is an important criterion for the diagnosis of diabetes and an indicator of the blood glucose level. The red blood cell (RBC) lifespan heterogeneity is sufficient to influence the HbA1c interpretation. In this study, we recruited 120 patients with diabetes mellitus and 85 nondiabetic controls. The HbA1c and the RBC lifespan were detected by high-performance liquid chromatography and the advanced carbon monoxide breath detection method, respectively. Potential correlations of gender and age with HbA1c were analyzed and a receiver operator characteristic curve was generated to get the HbA1c cut-off for every RBC lifespan group. It was confirmed that HbA1c has no correlation with gender or age. The correlation formula between the HbA1c diagnostic criteria and RBC lifespan was derived to correct the HbA1c diagnostic criteria using the least-square method. The RBC-lifespan-corrected HbA1c diagnostic criteria provided 100% sensitivity and specificity for the diagnosis of diabetes in the experimental set and was not refuted in the validated set. The diagnostic value of HbA1c is positively correlated with the RBC lifespan, and four patients with hyperglycemia, whose HbA1c values were lower than the general diagnosis criterion of 6.5%, were still considered to be diabetic according to this formula; that is, the application of this formula may help us to eliminate the 2.2% misdiagnosis rate of the current diagnostic criteria. To provide more accurate detection results, the effect of the RBC lifespan needs to be taken into account when HbA1c is used as a clinical indicator.

Carbon monoxide breath test assessment of mild hemolysis in Gilbert's syndrome.

BACKGROUND: Mild hemolysis is difficult to determinate by traditional methods, and its role in Gilbert's syndrome (GS) is unclear. The main aims were to inspect the erythrocyte (RBC) survival in GS by using Levitt's carbon monoxide (CO) breath test and to assess its contribution to unconjugated hyperbilirubinemia. METHODS: Fifty subjects with GS and 1 with type-II Crigler-Najjar syndrome (CN2) received RBC lifespan measurement with Levitt's CO breath test. Mean RBC lifespan was compared with normal referral value. Correlations of serum total bilirubin (TB) with RBC lifespan, blood panel data, demographic factors, and uridine diphosphate glucuronosyltransferase (UGT1A1) mutation load were calculated by Spearman analysis. Susceptibility factors for mild hemolysis were analyzed by multivariate regression analysis. RESULTS: The mean RBC lifespan of the GS subjects was significantly shorter than the normal reference value (95.4 ±â€Š28.9 days vs 126 days; t = -7.504, P < .01), with 30.0% below the lower limit of the normal reference range (75 days). The RBC lifespan of the participant with CN2 was 82 days. Serum TB correlated positively with UGT1A1 mutation load (γ = 0.281, P = .048), hemoglobin (γ = .359, P = .010) and hematocrit (γ = 0.365, P = .010), but negatively with RBC lifespan (γ = -0.336, P = .017). No significant susceptibility factors for mild hemolysis were found. CONCLUSIONS: The results indicate that mild hemolysis indeed, exists in a portion of patients with GS and might serve as an important contributor to unconjugated hyperbilirubinemia in addition to UGT1A1 polymorphism. Further studies on the mechanism and the potential risks in various medical treatments might be wanted.

Red Blood Cell Lifespan Shortening in Patients with Early-Stage Chronic Kidney Disease.

BACKGROUND: Although reduced red blood cell (RBC) lifespan has been reported to be a contributory factor to anemia in patients with end-stage chronic kidney disease (CKD), there are limited data regarding RBC lifespan in early-stage CKD. Serum erythropoietin (EPO) is considered a primary causative factor of renal anemia. The aims of this study were to compare the RBC lifespan, serum EPO levels, and other renal anemia indicators across CKD-stage groups of patients and to analyze the impacts of etiological factors on renal anemia. METHODS: A cohort of 74 non-smoking patients with CKD were enrolled, including 15 in stage 1, 18 in stage 2, 15 in stage 3, 15 in stage 4, and 11 in stage 5. RBC lifespan was determined by CO breath tests. Potential correlations of hemoglobin (Hb) concentration with RBC lifespan, reticulocyte count (Ret), and levels of EPO, ferritin, folic acid, and vitamin B12 were analyzed. RESULTS: CKD progression was associated with decreases in (Hb) and RBC lifespan. RBC lifespan durations in CKD stages 1-5 were 122 ± 50, 112 ± 26, 90 ± 32, 88 ± 28, and 60 ± 24 days, respectively. RBC lifespan means for the stage 3, 4 and 5 groups were significantly shorter than those for the stage 1 and 2 groups. Serum EPO did not differ significantly between the CKD stage groups. (Hb) correlated directly with RBC lifespan (r = 0.372, p = 0.002) and Ret (r = 0.308, p = 0.011), but did not correlate with serum EPO, ferritin, folic acid, or vitamin B12 levels. CONCLUSIONS: Reduced RBC lifespan in early-stage CKD, demonstrated in this study, suggests that increased RBC destruction may play a more important etiological role in renal anemia than other indicators in patients with CKD.

Effect of Hemodialysis on the Red Blood Cell Life Span in Patients with End-Stage Kidney Disease.

The aim of this study was to use a CO breath test to investigate hemodialysis effects on red blood cell lifespan in patients with chronic kidney disease. A cohort of 17 non-smoking men with end-stage kidney disease undergoing hemodialysis via a polysulfone dialysis membrane (as opposed to a traditional cellulose acetate membrane) were subjected to a repeated Levitt's CO breath test to compare red blood cell lifespan before vs. after dialysis. None of the patients showed significant fluctuations in endogenous CO concentration during the dialysis procedure. The mean red blood cell lifespan was 66.0 ± 31.0 days before dialysis and 72.0 ± 26.0 days after dialysis, with no significant difference between the assessment time points (P > 0.05). In conclusion, dialysis using a polysulfone membrane did not appear to disrupt red blood cells or reduce their lifespan in patients with end-stage kidney disease.

Human erythrocyte lifespan measured by Levitt's CO breath test with newly developed automatic instrument.

Existing standard techniques for erythrocyte (RBC) lifespan measurement, such as quantitation of labeling with isotopes or biotin, are cumbersome and time-consuming. Given that endogenous CO originates mainly from degraded RBCs, a team lead by Levitt developed a CO breath test to enable more efficient RBC lifespan estimation. The purpose of this study was to evaluate the reliability of Levitt's CO breath test method with our newly developed automatic instrument. RBC lifespan measurements conducted by Levitt's CO breath test method were conducted in 109 healthy subjects and 91 patients with chronic hemolytic anemia. In healthy subjects, the RBC lifespan was 126 ± 26 days, similar to values obtained with classical standard labeling methods. RBC lifespan did not differ significantly between males and females or between juveniles and adults, and did not correlate with age. To our knowledge, this datum represents an RBC lifespan average for the largest sample to date. In subjects with hemolytic anemia, RBC lifespan was 29 ± 14 days, which is significantly shorter than that of the healthy subjects (p = 0.001). Using 75 days as a cut-off, diagnostic accuracy for hemolytic anemia in the present study sample was 100%. In conclusion, the present results indicate that Levitt's CO breath test is an ideal method for human RBC lifespan measurement, and the newly developed automatic instrument is reliable and convenient for clinical practice.

Rapid CO breath test screening of drugs for protective effects on ribavirin-induced hemolysis in a rabbit model: a pilot study.

Hemolytic anemia is a major side effect of ribavirin antiviral treatment for chronic hepatitis C. Ribavirin dose reduction may compromise the antiviral response and erythropoietin can take several weeks to alleviate anemia. The purpose of the present study was to screen potentially protective drugs against ribavirin-induced hemolytic anemia in a rabbit model, using our modified CO breath test for measuring erythrocyte (RBC) lifespan, the gold standard diagnostic index of hemolysis. Fifteen rabbits were divided randomly into five groups (N = 3/group): one vehicle control group, one ribavirin (only)-treated (RBV) group, and three groups initially treated with ribavirin only, followed by a combination of ribavirin with prednisone (RBV + Pred), polyene phosphatidyl choline (RBV + PPC), or reduced glutathione (RBV + GSH). RBC lifespan was calculated from accumulated CO measured in a closed rebreath apparatus, blood volume measured by the Evan's blue dye (EBD) dilution test, and hemoglobin concentration data. The RBC lifespan was normal in the vehicle control group (44-60 d), but reduced significantly in all of the ribavirin-treated groups before the addition of screened drugs (17-35 d). RBC lifespan rebounded significantly with the addition of glutathione, but not with the addition of prednisone or polyene phosphatidyl choline. A similar overall drug effect pattern was seen in the hemoglobin concentration and reticulocyte count data. In conclusion, the results of this pilot study indicate that reduced glutathione can attenuate ribavirin-induced hemolytic anemia, and that the RBC lifespan measured with our modified rapid CO breath test is feasible and reliable for use in animal studies.

A Modified Carbon Monoxide Breath Test for Measuring Erythrocyte Lifespan in Small Animals.

This study was to develop a CO breath test for RBC lifespan estimation of small animals. The ribavirin induced hemolysis rabbit models were placed individually in a closed rebreath cage and air samples were collected for measurement of CO concentration. RBC lifespan was calculated from accumulated CO, blood volume, and hemoglobin concentration data. RBC lifespan was determined in the same animals with the standard biotin-labeling method. RBC lifespan data obtained by the CO breath test method for control (CON, 49.0 ± 5.9 d) rabbits, rabbits given 10 mg/kg·d(-1) of ribavirin (RIB10, 31.0 ± 4.0 d), and rabbits given 20 mg/kg·d(-1) of ribavirin (RIB20, 25.0 ± 2.9 d) were statistically similar (all p > 0.05) to and linearly correlated (r = 0.96, p < 0.01) with the RBC lifespan data obtained for the same rabbits by the standard biotin-labeling method (CON, 51.0 ± 2.7 d; RIB10, 33.0 ± 1.3 d; and RIB20, 27.0 ± 0.8 d). The CO breath test method takes less than 3 h to complete, whereas the standard method requires at least several weeks. In conclusion, the CO breath test method provides a simple and rapid means of estimating RBC lifespan and is feasible for use with small animal models.

[Determination of glyphosate in air of workplaces by ion chromatography].

OBJECTIVE: To establish a method for determining glyphosate in the air of workplaces by ion chromatography. METHODS: Ultra-fine glass fiber filter paper was used to collect glyphosate from the workplace air. After being ultrasonically eluted with deionized water, samples were determined by ion chromatography using a conductivity detector. RESULTS: Within the range of 0.05-1.00 mg/L, a linear relationship was found with a limit of detection of 0.003 mg/m(3). The minimum detectable concentration was 0.000 41 mg/m(3) (calculated by sampling 75 L of air). For three different concentrations of glyphosate, the intra-batch relative standard deviations (RSDs) were 1.8%, 1.6%, and 0.8%, respectively, and the inter-batch RSDs were 1.9%, 2.1%, and 2.2%, respectively. The recovery rate ranged from 94.8% to 97.4%. The elution efficiency ranged from 94.5% to 96.7%. The sampling efficiency was 100%. Samples could be stored at room temperature for at least 7 days. CONCLUSION: This presented method meets the requirements of Guide for establishing occupational health standards-Part 4: Determination methods of air chemicals in workplace and is feasible for determination of glyphosate in the air of workplaces.

Dietary exposure of the Chinese population to acrylamide.

OBJECTIVE: To assess the current status of the acrylamide in the Chinese food supply, the dietary acrylamide exposure in the Chinese population and to estimate the public health risks of the current consumption. METHODS: The acrylamide content in the total diet study (TDS) food samples was analyzed using an LC-MS/MS method. Based on the analytical results, the dietary exposure calculations were performed using a deterministic method, combining mean acrylamide concentrations from the food group composite with their associated food consumptions. RESULTS: Acrylamide was detected in 43.7% of all samples collected and acrylamide concentration varied from ND to 526.6 µg/kg. The estimated dietary intakes of acrylamide among Chinese general population given as the mean and the 95th percentile (P95) were 0.286 and 0.490 µg•kg(-1) bw•day(-1), respectively. The margins of exposure (MOEs) for the population calculated using both benchmark dose lower confidence limit for a 10% extra risk of tumors in animals (BMDL10) 0.31 and 0.18 µg•kg(-1) bw•day(-1), were 1069 and 621 for the mean dietary exposure, and 633 and 367 for the high dietary exposure respectively. CONCLUSION: These MOE values might indicate a human health concern on acrylamide for Chinese population. Efforts should continue to reduce acrylamide levels in food in order to reduce the dietary risks to the human health.

[Resident dietary exposure of cadmium in Jiangsu province].

OBJECTIVE: To investigate the resident dietary cadmium exposure in Jiangsu province and assess its safety. METHODS: Cadmium concentration of 229 food items under 12 food groups were obtained from the food surveillance program in Jiangsu province between 2001 and 2006. Food consumption data of 778 food items of 3938 residents who were classified into four age groups (< 7, 7-, 13-, 18-) were got from the Nutrition and Health Status Survey of the Jiangsu resident in 2002 by 24 h dietary recall on three consecutive days. Dietary cadmium exposures for the residents of different age groups were obtained by using both point estimation and simple distribution estimation through integrating the two datasets above. The safety of dietary cadmium exposure was assessed. RESULTS: Point estimation showed that the average dietary cadmium intakes of different age groups ranged from 5.7 to 8.6 microg/kg, accounting for 567.1% - 857.1% of the provisional tolerable daily intake (PTDI, 1.0 microg/kg). Result of simple distribution method showed mean daily cadmium exposure of different age groups ranged from 0.2 to 0.4 microg/kg, accounting for 20% - 40% of PTDI. Mean weekly cadmium exposure ranged from 1.4 to 2.5 microg/kg, accounting for 20% - 35.7% of the provisional tolerable weekly intake (PTWI, 7.0 microg/kg). The mean daily dietary cadmium exposure for different groups were as follows: < 7, 0.4 microg/kg; 7-, 0.3 microg/kg; 13-, 0.2 microg/kg; 18-, 0.2 microg/kg. Differences of daily dietary cadmium exposures among groups were significant (F = 69.0, P < 0.05). The mean weekly dietary cadmium exposure for different groups were: < 7, 2.5 microg/kg; 7-, 2.0 microg/kg; 13-, 1.4 microg/kg; 18-, 1.4 microg/kg. Differences of weekly dietary cadmium exposures among groups were also significant (F = 41.6, P < 0.05). The P97.5 of daily cadmium exposure for < 7 and 7- were 1.4 and 1.2 microg/kg, respectively, both of which were higher than PTDI. The P99.0 of daily cadmium exposure for 13- and 18- were 1.3 and 1.1 microg/kg, respectively. The daily dietary exposure from cereals for different age groups were 21.5 - 253.4 microg/kg, occupying 42.2% - 47.8% of the total daily exposure. Vegetables were 8.0 - 119.4 microg/kg, occupying 14.6% - 20.1%. CONCLUSION: The average level of dietary cadmium exposures for residents in Jiangsu province calculated by simple distribution estimation were much lower than that calculated by point estimation and were considered to be at no risk. P97.5 or P99.0 of daily or weekly dietary cadmium exposure of different age groups exceeded PTWI and PTDI. The main food types of dietary cadmium exposure were cereals and vegetables.

[Development and verification of Chinese dietary exposure evaluation model software].

OBJECTIVE: To develop the dietary exposure evaluation model software accredited of Chinese intellectual property rights and to verify the rationality and accuracy of the results from the probabilistic model in Chinese dietary exposure evaluation model software according to international standards. METHODS: The software of SAS was used to build various evaluation model based on the data from Chinese dietary survey and the chemical compound in food surveillance and to design an operation interface. The results from probabilistic dietary exposure model for children 2 - 7 years old were compared with that from duplicate portion study of 2-7 years children dietary exposure in Jinhu, Jiangsu province in order to analyze the rationality of model. The results from probabilistic model of dietary exposure were compared with the results from @Risk software to verify the correction of the probabilistic model by using the same data of randomly selected 10 000 study subjects from national dietary survey. While, the mean drift was used as an internal index to illustrate the accuracy of the computation. RESULTS: Chinese dietary exposure evaluation software was developed successfully. On the rationality, the results from probabilistic model were lower than that from the point estimation (e.g., cucumber: the result of point estimation of acephate was 4.78 microg x kg(-1) x d(-1), while the results of probabilistic model which was 0.39 microg x kg(-1) x d(-1)). Meanwhile the results from probabilistic model were higher than the results of duplicate portion study (on the P95, the result of probabilistic model of Pb exposure in children was 11.08 microg x kg(-1) x d(-1), while the results of duplicate portion study was 5.75 microg x kg(-1) x d(-1)). On accuracy, the results from @Risk and the probabilistic model were highly consistent (on the P95, the result of probabilistic assessment of acephate diet exposure was 4.27 microg x kg(-1) x d(-1), while the results of duplicate portion study was 4.24 microg x kg(-1) x d(-1)), and the mean drift was of random distribution, the drift region varied from 0.05% to 11.9%. CONCLUSION: The results computed by the software of Chinese dietary exposure evaluation model are reliable and reasonable, which is a meaningful step to improve the dietary exposure evaluation technique in China.