Automated turbidimetric assay of serum apolipoprotein A1 using the COBAS-BIO centrifugal analyzer

An automated turbidimetric procedure for determining serum concentrations of apolipoprotein A1 (apo A1) is described. This procedure allows for rapid, precise and inexpensive assay of apo A1 in large numbers of serum samples.     

甘油内空白法与GPO-POD法检测血清三酰甘油

目的 探讨甘油内空白法与甘油磷酸氧化酶(GPO)-过氧化物酶(POD)法测定生化质控血清中三酰甘油(TG)的差异.方法 采用两种方法测定7个不同品牌共17个批号生化室内质控血清和卫生部2006年常规化学室间质评样本三酰甘油,比较两法测定结果的异同.结果 甘油内空白法与GPO-POD法测定不同品牌不同批次生化室内质控血清三酰甘油的结果无明显相关,Roche与Leadman的TG结果可相差1倍以上;而Aalto和Bio Rad的结果非常相近.不同批次的卫生部室间质评样本结果与此类似.结论 部分品牌的生化质控血清含大量的游离甘油,两法测定质控血清的结果可能出现明显差异.     

Rapid determination of salicylate in serum on a centrifugal analyzer

A bichromatic method is described for the determination of salicylate using a micro centrifugal analyzer. Salicylate was quantitated based on its reaction with ferric ion to produce a violet-colored complex. The method provides sample blanking and allows for rapid determination of salicylate levels in serum.     

Automated fibronectin assay using light-scattering optics on a centrifugal analyzer

We describe an automated, kinetic nephelometric method for fibronectin on the Multistat III F/LS Centrifugal Analyzer (Instrumentation Laboratory Inc., Lexington, MA 02173). Antiserum is diluted with polyethylene glycol. Calibrators and samples are prediluted with potassium phosphate buffer (10 mmol/L, pH 7.0) containing 8.5 g of NaCl per litre. Intensity (I) is read at 5 and 180 s and the resulting delta I plotted against concentration. A non-linear least squares curve fitting and interpolation of results is carried out automatically. Three controls, with values of between 190-370 gave coefficients of variation between 4 and 7 percent, and the sensitivity of the method is to 25 mg/L.     

A one-step determination of serum 5'-nucleotidase using a centrifugal analyzer

We describe a one-step kinetic method for the determination of 5'-nucleotidase (EC 3.1.3.5). Inosine is formed by the hydrolysis of inosine 5'-monophosphate which is catalyzed by seric 5'-nucleotidase, and then is converted to hypoxanthine by nucleoside phosphorylase. Two moles of hydrogen peroxide are formed for each mole of hypoxanthine oxidized to urate by xanthine oxidase. The rate formation of hydrogen peroxide is monitored at 510 nm using the oxidation of the chromogenic system 3,5-dichloro-2-hydroxybenzenesulfonic acid/4-aminophenazone in the presence of peroxidase. beta-Glycerophosphate inhibits the unspecific cleavage of the substrate by alkaline phosphatases. Inorganic phosphate is added to improve the reagent stability, and ferrocyanide to reduce bilirubin interference. Automation of the technique requiring 20 microliter of serum on a centrifugal analyzer is also described.     

北京居民血清游离甘油水平及其对甘油三酯水平分类的影响

目的调查血清游离甘油(FG)水平及其与血清甘油三酯(TG)、年龄、性别等的关系，探讨FG对血清TG水平划分的影响。方法用高效液相色谱法测定480例北京居民血清FG，用酶法测定总甘油(1TrG)，分析FG与TG、年龄和性别的关系及FG对TG水平划分的影响。结果480例北京居民血清FG平均值0．082mmol／L，中位数0．075mmol／L；FG／TG平均值8．0％，中位数6．4％；FG和FG／TG女性明显高于男性；TG和TTG高于目前医学决定水平1．69mmol/L(150mg／d1)的个体分别占22％和25％。结论按新的方案对血清TG水平划分，临床TG测定更需具备去除游离甘油的能力。     

Improved method for measurement of inorganic phosphate in serum with a centrifugal analyzer.

A direct mehtod [Clin. Chim. Acta 46, 113 (1973)] for determination of inorganic phosphate in serum was adapted for use with a centrifugal analyzer. Contamination is minimized and analysis rate maximized by doing the reaction in the reagent wells of the transfer disc and by utilizing the high-speed spectrophotometric and data-reduction capabilities of the centrifugal analyzer. Hemolysis, icterus, and moderate lipemia cause no interference. Grossly lipemic sera and sera from patients with plasma cell dyscrasias can be analyzed by incorporating appropriate blanking and dilution techniques. The method exhibits excellent sensitivity and precision and results correlate well with those from a continuous-flow procedure.     

Enzymic measurement of urinary pyrophosphate with a centrifugal analyzer

We describe a simple, rapid, and fully automated technique for measuring urinary pyrophosphates with a centrifugal analyzer (the ENI GEMSAEC). This technique depends on the enzymic magnesium-dependent reaction with UDPG pyrophosphorylase (UTP: alpha-D-glucose-1-phosphate uridylyl transferase, EC 2.7.7.9) and spectrophotometry of the NADPH formed in a combined system of phosphorylation and reduction. Many samples of urine can be analyzed quickly without pretreatment, with high sensitivity (1.3 mA/mumol of substrate) and good reproducibility. The mean within-run coefficient of variation for a 50 mumol/L pyrophosphate solution was 1.4%. We determined the optimum enzyme and magnesium concentrations necessary for use in a 4-min reaction. Because there is no inhibitory effect of chloride and phosphate ions, pyrophosphate can be measured directly in urine, without prior extraction. With this technique, the mean value (and SD) for urinary pyrophosphate excretion by 30 healthy subjects was 39.3 (SD 17.2) mumol/24 h.     

Kinetic measurement of alpha-amylase with a centrifugal analyzer.

We compared results of an enzymic assay for alpha-amylase (EC 3.2 1.1), adapted to a centrifugal analyzer (GEMSAEC), with results by the manual dyed-starch (Phadebas) amylase assay. We assessed linearity and precision, and the stability of the reagent. The kinetic procedure is rapid, precise, requires only 25 microliter of serum, and thus is evidently suited for both pediatric and emergency use.     

Enzymatic determination of acetate in serum or plasma using a centrifugal fast analyser

A simple enzymatic spectrophotometric micromethod is described for direct kinetic assay of acetate in serum or plasma using the Eni-Gemsaec centrifugal fast analyser. The method is based on the transformation of acetate and ATP into acetylphosphate and ADP by acetate kinase (EC 2.7.2.1). ADP is further measured by two coupling reactions involving pyruvate kinase (EC 2.7.1.40) and lactate dehydrogenase (EC 1.1.1.27) with measurement of NADH consumption at 340 nm.The method involves a reagent blank for compensation of reagent deterioration, a preincubation of 3 min without acetate kinase to eliminate any interference due to endogenous pyruvate, and a two-point kinetic protocol with measurements of absorbance at 95 s and 395 s. The analytical performances of the proposed method were investigated using an evaluation scheme proposed by the French Society of Clinical Biology.     

Kinetic determination of serum haptoblobin with a centrifugal analyzer.

We describe a method for determining haptoglobin with a centrifugal analyzer that is based on haptoglobin combining stoichiometrically with hemoglobin to form a complex that has peroxidase-like activity proportional to the quantity of haptoglobin present. Under assay conditions, unbound hemoglobin exhibits only a small fraction of the total peroxidase activity. Activity is measured colorimetrically at 405 nm after reaction with o-dianisdine and ethyl hydrogen peroxide. The procedure is standardized by saturating aknown amount of hemoglobin with a serum whose hemoglobin binding capacity exceeds the amount of hemoglobin in the assay system. The mean and mean within-run precision of our method, determined by performing 17 replicate assays of both a pooled normal serum and a 10-fold dilution of the serum, was 1.13 g/liter (CV, 2.9%), and 106 mg/liter (cv, 5.8%), respectively. The 95 percentile estimate of the normal range by our method is 0.45-1.85 g/liter hemoglobin binding capacity. When results by our automated method were compared to those by a manual method [Scand. J. Clin. Lab. 2nvest. 18, 80 (1965)], the slope of the unweighted linear least-squares regression line was .970 the y-intercept 26 mg/liter, and the correlation coefficient .995.     

Determination of serum 5'-nucleotidase with a centrifugal analyzer.

We describe a multi-point method for the determination of the serum enzyme activity 5'-nucleotidase by means of an NADH sensor reaction. Studies show that the assay may be carried out in one step, without preincubation, by using a GEMSAEC Fast Analyzer.     

Rapid quantitation of serum immunoglobulins with a miniature centrifugal analyzer

For these quantitative turbidimetric assays for immunoglobulins IgG, IgA, and IgM in serum, the reagents used are commercially available in kit form. The two-point assays are performed with a miniature centrifugal analyzer (GEMENI, Electro-Nucleonics, Inc.). The reading taken 5 s after mixing is used to correct for specimen turbidity. Run-to-run precision (CV) was typically 5% (range: 3.0-8.7%). Excellent correlation with radial immunodiffusion was observed for each test (r greater than 0.98 for each test). The dynamic range of each test extends above and below the reference-interval ranges.     

A turbidimetric immunochemical method for determination of serum beta 2-microglobulin using a centrifugal analyzer

A turbidimetric immunochemical method has been developed for quantitation of serum-beta 2-microglobulin. The serum samples are pre-treated with polyethyleneglycol to decrease the background turbidity and a centrifugal analyzer is used for the absorbance measurements. The within-assay coefficient of variation was 4.6% when 58 serum samples with a mean value of 2.0 mg/l were analyzed in duplicate. The sensitivity of the method is below 0.5 mg/l. When serum samples were analyzed by both the turbidimetric method and a radioimmunoassay a correlation coefficient of 0.989 was obtained. The turbidimetric method is simple, cheap and has a high capacity which makes it suitable for routine determinations of serum beta 2-microglobulin in a clinical laboratory.