Objective To investigate the stability and comparability of recombinant human muscle creatine kinase isozyme(CK-MM)in different matrix,and to find out a suitable matrix as a reference material for application of CK measurement system.Methods The stability of the recombinant CK-MM was observed by measuring its catalytic activity in self-made matrix,anti-freeze additive matrix,the certified reference material(CRM)matrix and human serum matrix respectively.For understanding the commutability among different measurement system total CK catalytic activity in various concentration of human serum and the catalytic activity of recombinant CK-MM in different matrix specimen were measured with IFCC recommended reference method and routine reagent produced by Roche and Zhongsheng Diagnostic Company respectively.Results The recombinant CK-MM was stable for 25 days in the self-made matrix,23 days in CRM matrix and at least 240 days in antifreeze additive matrix stored at-20 ℃.The recombinant enzyme protein in self-made matrix and CRM matrix was commutable.Low concentrations of recombinant CK-MM in human serum and in anti-freeze additive matrix were also commutable.Conclusion The recombinant CK-MM had good stability and commutability in either self-made matrix or CRM matrix.It might be used as a candidate reference material for the determination of total creatine kinase in serum.

BNP (B-type natriuretic peptide) and NT-proBNP (N-terminal pro-B-type natriuretic peptide) are peptide hormones secreted by the heart.Recently, many researches have described that BNP and NT-proBNP were useful markers for the diagnosis of heart failure.We should develop these assays correctly on the basis of full understanding of biological characteristics and guide clinical use for them in medical laboratories.

Chronic kidney disease ( CKD) has become a pandemic.Laboratory assay takes the important role in early diagnosis of CKD.We should develop these assays correctly on the basis of full understanding of CKD and guide clinical use for them in laboratory medicine.

Objective To analyze the performance of a rapid immunofluorescence assay for plasma NT-proBNP. Methods Human plasma NT-proBNP was measured by RAMP in 264 healthy cases and 78 patients with heart failure. The precision, stability, linearity and interference factors of RAMP were evaluated according to the protocold from America CLSI. Meanwhile, the results were compared with those obtained by Elecsys. Results Functional sensitivity of RAMP in 20% CV and 10% CV were 48 ng/L and 57 ng/L respectively. The linear range was 18-8 000 ng/L. NT-proBNP in plasma samples detected by RAMP were stable at room temperature for 24 hours, 4 ℃ for 3 days and - 20 ℃ for 20 days. No influences on results were observed throughout three freeze-thaw cycles. The results measured by RAMP were compared between EDTA-K2 anticoagulant plasma and heparin anticoagulant plasma, which showed that YEDTA-K2 =0. 953 9 Xheparin + 0. 365 2 ( R2 = 0. 982, P < 0. 01, n = 40 ). The results of EDTA-K2 and heparin anticoagulant plasma using RAMP and Elecsys showed no significant difference( P ＞0. 05). Slight hemolysis( Hb 2 g/L)had small effect on the results of PAMP and Elecsys assays and deviations of them were below 5%. However median and heavy hemolysis( Hb 3-4 g/L )obviously influenced the results with deviation were more than 15%. The values measured by RMAP fell from 390 ng/L to 82 ng/L, and those measured by Elecsys method fell from 390 ng/L to 178 ng/L when 3 different concentrations of triacylglycerol were added, the values measured by two methods fell from 7 777 ng/L to 7 741 ng/L when bilirubin ( 16-330 μmol/L) was added. The anti-interference ability of RAMP method was similar to Elecsys. Results detected with two methods in 45 EDTA-K2 anticoagulant plasma samples were analyzed with Passing and Bablok regression.The regression equation was YRAMP = 0. 972 8XElecsys - 0. 035 2 (R2 = 0. 994, P ＞ 0. 05, n = 45 ). When heparin anticoagulant plasma samples increased to 78 samples, Passing and Bablok regression equation showed:YRAMP= 0. 983 2XElecsys - 0. 037 6 ( R2 = 0. 991, P ＞ 0. 05, n = 78 ). NT-proBNP levels in healthy adults were elevated along with age and related to the gender. The median value of female[105(60-120) ng/L] was higher than that of male [59 ( 44-91 ) ng/L, Z = 3. 264, P < 0. 01] significantly. Conclusions RAMP method has good repeatability, outstanding stability, and broad linear range. The results detected by RAMP is consistent with results detected by Elecsys.

Chronic kidney disease (CKD) is a general term for heterogeneous disorders affecting kidney structure and function.It can be detected by routine laboratory tests.Acute kidney injury ( AKI),previously referred to as acute renal failure(ARF), represents a persistent problem in clinical medicine.Despite significant improvements in therapeutics,the mortality and morbidity associated with AKI remain high.A major reason for this is the lack of markers for early diagnosis of AKI.In this paper,we discuss recommendations for AKI and CKD laboratory assessment and management,and future challenges.( Chin J Lab Med,2012,35:773-779)

0.5). Conclusions There is an increasing trend of resistin level in healthy volunteers and patients with obesity, diabetes mellitus and hyperthyroidism in order Resistin also was a positive and an inverse correlation with BMI and resistance index respectively. These results support the hypothesis of Steppan that resistin causes insulin resistance and links obesity to diabetes, and that the high level of resistin in hyperthyroidism can help to explain the phenomenon of its insulin resistance.

74 years were associated with increased cardiac events too(HR = 5.40,95%CI:2.16~11.52,P=0.0002).NYHA classification, LVEF, cTnT?cTnI and CK-MB were not independently predictive of cardiac events.Conclusions Measurement of NT-proBNP in patients with CHF can help to identify patients at higher risk for cardiac events .

Objective To evaluate the analytical variables of the reversed-phase high pressure liquid chromatography (HPLC) with 5-Fluorouracil(5-Fu) as an internal standard for determining creatinine in human serum and urine. The method was used as a candidate reference method for accuracy assessment of routine creatinine test kits.Methods We tested the accuracy, precision, linearity of the reversed-phase HPLC.We analyzed split samples of a panel of 85 patients’ serum and 94 patients’ urine and compared the results of the routine test kits and HPLC by means of bias plots (percentage differences of results) and standard linear regression.Results The linear range of HPLC method was up to 2 210 ?mol/L, the within-run CV(n=5) was below 2.5% and the between-day CV(n=10) was less than 4.5%. The analytical recovery rate was 96.3%～102.4%. All of the test kits correlated very well with HPLC.Conclusions We recommend the reversed-phase HPLC with 5-Fu as an internal standard as a candidate reference method for determining creatinine in human serum and urine.The enzymatic method with creatininase coupled sarcosine oxidase is suitable for routine work in clinical laboratories.

Objective To investigate the influence of renal function on serum NT-proBNP in the diagnosis of chronic heart failure by observing the relationship between eGFR and NT-proBNP in serum and comparing cutoff values of NT-proBNP in different eGFR levels.Methods 297 elderly participants were enrolled in the study, including 106 inpatients with heart failure and 191 healthy controls in the corresponding period.The concentration of NT-proBNP was determined by an automated electrochemiluminescence immunoassay on Roche Elecsys 2010.Estimated glomerular filtration rate (eGFR) was calculated using the Levey-modified Modification of Diet in Renal Disease formula. The diagnosis of clinical physician was considered to be the golden standard for heart failure.Results Serum NT-proBNP levels were significantly higher in subjects with renal dysfunction compared with those with normal renal function for heart failure patients [829.1 (202.4 ~ 3725.5) ng/L vs. 227.2 (111.1 ~ 964.2) ng/L, P

Objective To compare the clinical effect of valsartan/amlodipine combination or irbesartan/hydrochlorothiazide(HCTZ)combination in very elderly hypertensives.Methods After a 4-week placebo period,94 hypertensives,aged 75-89 years were random given valsartan 160 mg/amlodipine 5 mg or irbesartan 300 mg/HCTZ 12.5 mg for 24 weeks according to a rospective study.After 4 weeks,amlodipine or HCTZ was doubled in non-responders.Patients were checked every 4 weeks.At each visit,sitting,lying and standing blood pressure(BP),systolic BP(SBP)and diastolic BP(DBP)were measured. At the end of placebo period and treatment period,electrolytes and uric acid were evaluated.Results Blood pressure was significantly decreased in both treatment groups,however,there was no statistical significance between two groups.BP changes from lying to standing position were significantly greater in the irbosartan/HCTZ group(-17.2/-9.1 mmHg)than that in the valsartan/amlodipine group(-10.1/-1.9 mmHg,t=2.14,P＜0.05 for SBP and t=3.11,P＜0.01 for DBP vs.irbesartan/HCTZ).Potassium significantly decreased and uric acid significantly increased(-0.4 mmol/L,t = 2.33,P＜ 0.05 and+29.7μ mol/L,t =2.54,P＜0.05 vs.baseline,respectively)only in the irbesartan/HCTZ group.Conclusions Both combinations had similarly effective in reducing clinical BP in very elderly hypertensives.However,valsartan/amlodipine offered some advantage and less pronounced BP orthostatic changes and absence of metabolic adverse effects.