Semi-automated direct colorimetric measurement of creatine kinase isoenzyme MB activity after extraction from serum by use of a CK-MB-specific monoclonal antibody.

This semi-automated colorimetric assay for the MB isoenzyme of creatine kinase (EC 2.7.3.

Effect of tetrasodium EDTA on enzymatic determinations of urinary oxalate.

We studied the effects of pretreating urine samples with tetrasodium EDTA (TEDTA) before measuring urinary oxalate with an enzymatic kit (Sigma). Mean analytical recovery of added oxalic acid was only 49% (SD +/- 13%) when the assay was performed as recommended by the manufacturer, but treating samples with TEDTA improved recoveries (96 +/- 10%). In 20 unselected 24-h urine samples assayed with and without TEDTA treatment, the mean oxalate concentrations were significantly (P less than 0.

Constancy of serum angiotensin-converting enzyme activity in normal and complicated pregnancy.

Angiotensin-converting enzyme occupies a central position in the dynamics of the renin-angiotensin system. We prospectively studied serum angiotensin-converting enzyme activity in 112 women at various stages of pregnancy and in the postpartum period because converting enzyme levels have not been well documented in pregnant women with medical disorders which might be expected to influence intravascular volume or blood pressure. Enzyme activity is lower during pregnancy than it is in the same population at 6 weeks postpartum.

Lidocaine stability in cardioplegic solution stored in glass bottles and polyvinyl chloride bags.

The stability of lidocaine hydrochloride in buffered cardioplegic solutions stored in glass and polyvinyl chloride bags was studied. Concentrations of lidocaine (incorporated as the hydrochloride salt) were measured in buffered cardioplegic solutions containing potassium chloride, sodium bicarbonate, dextrose, and sodium chloride. Solutions were stored at 22 +/- 2 degrees C and 4 degrees C in glass bottles and 500-ml and 250-ml polyvinyl chloride (PVC) containers; some 250-ml PVC bags were underfilled to study the effects of varying surface area-volume ratios.