Quantitative turbidimetric assay for determining myoglobin evaluated.

A recently introduced turbidimetric immunoassay using shell/core particles for determination of myoglobin (Turbiquant Myoglobin, Behringwerke, Marburg, Germany) was evaluated on the Behring Turbitimer analyzer. Intra-assay CV varied between 1.0% and 3.2%; interassay CV was between 2.0% and 3.6%. Linear results were obtained between 2.8 nmol/L and 36.7 nmol/L. Manual dilution in saline solution allowed measurement of myoglobin concentrations up to 25,400 nmol/L. In the tested range, no high-dose 'hook' effect was observed. Haemolysis interfered with the assay when haemoglobin concentrations exceeded 2 g/L. The occurrence of error codes due to the presence of triglycerides was shown to depend on particle size. Repeat assays on diluted samples were necessary at triglyceride concentrations of 2.3 mmol/L for post-prandial chylomicrons (200-1000 nm), and at 11-31 mmol/L for very-low density lipoprotein-triglycerides (80-200 nm). No significant interferences of haptoglobin, bilirubin, iodine containing contrast media, and rheumatoid factors were detected for the assay. Treatment of lipaemic samples with Lipoclean (Behringwerke) resulted in lower myoglobin values. Simultaneously drawn serum and heparin-plasma samples gave comparable myoglobin results. However, values obtained in EDTA- or citrate-treated plasma samples occasionally differed significantly from serum values. The upper reference limit for myoglobin concentration was 4.2 nmol/L. The turbidimetric assay correlated well with a radioimmunoassay (Byk-Sangtec; r = 0.892) and with the automated nephelometric assay (Behringwerke; r = 0.944). Values obtained by turbidimetry were comparable to those obtained by the latex agglutination test (Behringwerke).

Automated quantification of creatine kinase MB isoenzyme in serum by radial partition immunoassay, with use of the Stratus analyzer.

We evaluated the analytical and clinical performances of a new radial partition immunoassay for measuring the mass concentration of creatine kinase (CK)-MB in serum. All pipetting, washes, incubations and data reduction were performed in 8 min by the Stratus (Dade) fluorometric analyzer. Within-assay and between-assay CVs were respectively 5.5% and 8.4% at 21 micrograms/L, and 4.2% and 3.4% at 48 micrograms/L. Assaying serial dilutions of serum samples with high CK-MB concentrations demonstrated excellent linearity. Results of the Stratus technique correlated well (n = 115, r = 0.98) with those of the Tandem-E CKMB II assay. There was no interference from hemolysis, bilirubin, rheumatoid factor, or added CK-MM (up to 3500 U/L); consequently, CK-MB can be determined in undiluted serum, even in the presence of high total CK activity. The mean CK-MB concentration in 105 blood donors was 1.9 (SD 1.3) micrograms/L. For seven myocardial infarction patients who received prompt fibrinolytic therapy, the mean CK-MB concentration was 4.5 (SD 1.8) micrograms/L at admission, and maximum concentrations, 119 (SD 94) micrograms/L, were recorded 16 h later. CK-MB returned to concentrations less than 10 micrograms/L within 72 h.

[The role of plasma alpha 1-glycoprotein acid in the binding of aminopyrine]. / Rôle de l' alpha 1-glycoprotéine acide plasmatique dans la fixation de l'aminopyrine.

Under certain pathological conditions the binding of various substances by serum proteins is altered. The plasma concentrations of alpha 1-acid glycoprotein, also known as orosomucoid are reported to be elevated in stressful situation and in certain disease states like acute myocardial infarction. The binding of aminopyrine to serum proteins and alpha 1-acid glycoprotein was determined using equilibrium dialysis. It appears that alpha 1-acid glycoprotein has specific binding sites for aminopyrine. Aminopyrine was also bound to other serum proteins. On addition the results indicate that an increase of alpha 1-acid glycoprotein to concentrations such as those seen in some pathological states does not really alter the percent of aminopyrine bind to serum proteins.

The value of serum CK-MB and myoglobin measurements for assessing perioperative myocardial infarction after cardiac surgery.

In 41 patients who underwent coronary bypass surgery, creatine kinase (CK)-MB mass concentration was repeatedly measured in serum during and after the intervention using a new two-site immunoenzymetric assay (IEMA). Serum CK-MB activity was determined with the use of four different techniques: immunoinhibition, immunoinhibition-immunoprecipitation, column chromatography and electrophoresis. Myoglobin (Mb) was also measured in each specimen by radioimmunoassay. In the 33 patients who followed a completely uneventful postoperative course, the cumulated CK-MB release was, on the average, 12.2-fold less than after acute myocardial infarction. The CK-MB peak concentrations using the IEMA were 33 +/- 3 micrograms/l (X +/- SEM) and occurred 6.4 +/- 0.5 h after the intervention was started; CK-MB levels had decreased to 2.9 +/- 0.4 micrograms/l at the end of the first postoperative day. The evolution of the CK-MB concentration was parallel to that of the enzyme activity. The serum Mb maximum concentrations (518 +/- 39 micrograms/l) were reached after 3.3 +/- 0.1 h. The other eight patients developed perioperative myocardial infarction (PMI); in this group, the cumulated CK-MB release was higher, and the serum CK-MB postoperative curves were of three different types. The patients with delayed CK-MB peaks (type I pattern) or sustained elevations (type III) of this isoenzyme also showed increased serum Mb levels at the end of the first postoperative day. The PMI patients with early (10 h) CK-MB elevations (type II) did not demonstrate abnormal serum Mb levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Serum creatine kinase isoenzyme MB concentration after endomyocardial biopsy.

Serum total creatine kinase (CK), CK-MB and myoglobin (Mb) were serially determined in 17 patients who underwent endomyocardial biopsy. Mean total CK levels increased from 36 +/- 27 U/l 30 min before biopsy to a maximum of 112 +/- 77 U/l 8 h following the procedure (p less than 0.05). Similarly, Mb concentrations rose from 57 +/- 55 micrograms/l to 119 +/- 57 micrograms/l 30 min after biopsy (p less than 0.05). Normalization of total CK and Mb levels occurred within 16 and 8 h, respectively. A new immunoenzymetric assay (IEMA) was used to measure the mass concentration of the CK-MB molecule. The initial CK-MB levels were 0.2 +/- 0.4 microgram/l; a small but significant elevation was recorded as early as 2 h after biopsy (1.6 +/- 1.5 micrograms/l, p less than 0.05). CK-MB returned to initial concentration 16 h after the beginning of the procedure. Comparison with the maximum CK-MB levels recorded in 16 myocardial infarction patients (258 +/- 172 micrograms/l, range 90-680 micrograms/l) indicated that the modest increase of CK-MB level detected after biopsy probably reflects a limited endomyocardium lesion at the sampling site, excluding any significant myocardial damage. Total CK and Mb, which showed more pronounced elevations than CK-MB, are likely to originate from other sources than the myocardium.

Differentiating muscle damage from myocardial injury by means of the serum creatine kinase (CK) isoenzyme MB mass measurement/total CK activity ratio.

We immunoenzymometrically measured creatine kinase (CK) isoenzyme MB in extracts of myocardium and in homogenates of five different skeletal muscles. CK-MB concentrations in the former averaged 80.9 micrograms/g wet tissue; in the skeletal muscles it varied widely, being (e.g.) 25-fold greater in diaphragm than in psoas. CK-MB in skeletal muscles ranged from 0.9 to 44 ng/U of total CK; the mean for myocardium was 202 ng/U. In sera from 10 trauma and 36 burn patients without myocardial involvement, maximum ratios for CK-MB mass/total CK activity averaged 7 (SEM 1) ng/U and 18 (SEM 6) ng/U, respectively. Except for an infant (220 ng/U), the highest ratio we found for serum after muscular damage was 38 ng/U. In contrast, the mean maximum ratio determined in 23 cases of acute myocardial infarction exceeded 200 ng/U. Among seven determinations performed 8 to 32 h after onset of symptoms, each infarct patient demonstrated at least one ratio greater than or equal to 110 ng/U. Ratios observed after infarct were unrelated to treatment received during the acute phase. We propose a CK-MB/total CK ratio of 80 ng/U as the cutoff value for differentiating myocardial necrosis from muscular injury.

[Development of urea, creatinine and creatinine clearance as a function of age and sex]. / Evolution, en fonction de l'âge et du sexe, de l'urée, de la créatinine et de la clairance de la créatinine.

Serum urea and creatinine concentrations were determined in 150 healthy subjects. The formula of Cockcroft and Gault was used in order to calculate creatinine clearance. Such estimation of creatinine clearance is widely used as a parameter for individualization of dosage of drugs secreted primary via the kidneys. The effects of age and sex were then assessed on serum urea, serum creatinine and on creatinine clearance.