Development and evaluation of assays for the determination of total and pancreatic amylase at 37 degrees C according to the principle recommended by the IFCC.

OBJECTIVES: The aim of our study was a) to optimize assays for measurement of total (T-) and pancreatic (P-)amylase at 37 degrees C based on the principle recommended by the IFCC at 30 degrees C, b) to evaluate the analytical performance of these assays in a multicentric study and c) to establish reference intervals for serum and urine for either method. METHODS: Optimized conditions for 37 degrees C were elaborated with regard to substrate concentration, pH, inorganic additives and glucosidase activity. The cleavage pattern of the EPS substrate was studied by HPLC. Liquid ready-to-use reagents for T- and P-amylase were provided to six European laboratories. RESULTS: The assays showed good performance characteristics (median intraassay CVs 1.0% for T- and 1.3% for P-amylase, median interassay CVs 3.0% for either assay, dynamic range 15-fold URL for T- and 30-fold for P-amylase), high correlation with the previous EPS methods (r > 0.996, slope 0.43, intercept < 5 U/L) in serum, heparin plasma and urine and good analytical specificity of the P-amylase assay (residual S-amylase activity 2.4%). Serum reference ranges were found to be 28 to 100 U/L for T- and 13 to 53 U/L for P-amylase (n = 775); URLs in urine were estimated as 490 U/L or 280 U/g creatinine for males and 450 U/L or 380 U/g creatinine for females with total amylase. CONCLUSION: We believe that these assays based on the 30 degrees C IFCC recommendation represent a further improvement in amylase methodology at 37 degrees C and merit broad application in clinical routine.

Leukocytapheresis: evaluation of a new procedure for the blood cell separator Fresenius AS 104.

For granulocyte separation from peripheral blood with the Fresenius blood cell separator AS 104 a new procedure and a new tubing set were developed and evaluated. Separation is done in cycles of 400 ml of whole blood processed, with continuous blood flow of 50-55 ml/min, speed 750 rpm. HES-450 is added for sedimentation acceleration together with citrate, ratio 1:10. At the end of each cycle granulocytes were pumped out of the separation chamber into the collection container. After processing 13 cycles of 400 ml whole blood/HES-citrate-volume a total yield of 9.20 +/- 2.80 x 10(9) white cells were collected in volumes of 125 ml. 47 +/- 9% of the leukocytes collected were granulocytes, this corresponds to collection of 1.05 +/- 0.09 x 10(9) granulocytes per liter of processed blood. The efficacy of granulocyte collection is 22.5 +/- 5.6%, viability is more than 95%. With this procedure it is possible to collect granulocytes with the blood cell separator Fresenius AS 104 in therapeutical doses.

The lecithin/spingomyelin quotient as determined using a modified method and human placental lactogen in the amniotic fluid. / Der Lezithin/Sphingomyelin-Quotient, bestmmt nach einer modifizierten Methode, und HPL im Fruchtwasser

Thirty amniotic fluid samples in late gestational age were analysed for HPL-values and the L/S-ratio. The pregnant women used in this study were healthy except three patients who developed a rh-incompatibility. The amniotic fluid was only obtained by abdominal amniocentesis. We found a decreasing tendency of the HPL-values in late pregnancy. The L/S-ratio increased. A significant correlation of both values could not be observed. In all three cases of rh-incompatibility the decrease of HPL and the increase of the L/S-ratio occurred obviously earlier and steeper. Further studies will prove the significance of these results.