Isolated subacromial bursal fluid on MRI of the shoulder in symptomatic patients: correlation with arthroscopic findings

Fluid in the subacromial bursa (SAB) is a common finding on magnetic resonance (MR) images of the shoulder, and the implications of this finding have not been clarified. We retrospectively reviewed and correlated the MR features with arthroscopic findings in 21 symptomatic patients who had fluid in the SAB on MR imaging without demonstrable rotator cuff tear. Rotator cuff impingement was the most frequent surgical finding (42.9%). Other frequent surgical observations were glenoid labrum abnormality (28.6%), bursitis (19%), and supraspinatus tendinitis (14.3%). Distribution of acromial types was similar to that reported by Bigliani et al., and impingement was evenly distributed among acromial types in our study population. We conclude that in our patient population group the MR finding of isolated SAB fluid in symptomatic patients is highly likely to be associated with the finding of other abnormalities in the shoulder joint at surgery.

Effect of two anticoagulants on leukocyte yield and function, and on lysosomal enzyme activity

We compared acid citrate-dextrose (ACD-B) and heparin to determine which anticoagulant better preserves leukocytes for lysosomal enzyme assays if processing was done immediately or delayed for 24 h or more. Twenty normal subjects had blood drawn into tubes containing either ACD-B or heparin. The leukocytes were isolated by sedimentation in dextran (50 g/L) less than 2, 24, 48, and 72 h later. The most apparent difference was that cell counts indicated a 30% reduction in the number of leukocytes for ACD-B and a 95% reduction for heparin-treated cells at 48 h. The neutrophil function assay indicated that leukocyte processing must be done in less than 24 h regardless of the anticoagulant used, and that heparin is to be preferred. A comparison of heparin and ACD-B for maintenance of the activity of arylsulfatase A (EC 3.2.6.1) and hexosaminidase (EC 3.2.1.50) indicates that there is no effect of anticoagulant. However, at 48 h after venipuncture, there is an 80% reduction in the number of heparin-treated samples that are suitable for use in the assay. Those laboratories doing lysosomal enzyme tests on mailed specimens, which are most often greater than 24 h old, should use ACD-B as anticoagulant.

Effect of two anticoagulants on leukocyte yield and function, and on lysosomal enzyme activity

We compared acid citrate-dextrose (ACD-B) and heparin to determine which anticoagulant better preserves leukocytes for lysosomal enzyme assays if processing was done immediately or delayed for 24 h or more. Twenty normal subjects had blood drawn into tubes containing either ACD-B or heparin. The leukocytes were isolated by sedimentation in dextran (50 g/L) less than 2, 24, 48, and 72 h later. The most apparent difference was that cell counts indicated a 30% reduction in the number of leukocytes for ACD-B and a 95% reduction for heparin-treated cells at 48 h. The neutrophil function assay indicated that leukocyte processing must be done in less than 24 h regardless of the anticoagulant used, and that heparin is to be preferred. A comparison of heparin and ACD-B for maintenance of the activity of arylsulfatase A (EC 3.2.6.1) and hexosaminidase (EC 3.2.1.50) indicates that there is no effect of anticoagulant. However, at 48 h after venipuncture, there is an 80% reduction in the number of heparin-treated samples that are suitable for use in the assay. Those laboratories doing lysosomal enzyme tests on mailed specimens, which are most often greater than 24 h old, should use ACD-B as anticoagulant.

Macroenzyme as a cause of unexplained elevation of aspartate aminotransferase

Aspartate aminotransferase (AST) can exist as a macroenzyme by forming a complex with an immunoglobulin. This immunoglobulin-complexed macromolecule can cause an elevation in serum AST activity, which may be detected on routine blood chemistry analysis and erroneously considered to indicate the presence of liver disease. Clinicians should be aware of this phenomenon so patients are not subjected to unnecessary procedures. In patients with unexplained AST elevation, liver and muscle disease can be biochemically excluded by the finding of normal serum levels of alanine aminotransferase and creatine kinase. The presence of macro-AST can be determined by exclusion chromatography, electrophoresis, and activation assays with pyridoxal 5-phosphate. The elevated AST values can persist for many years.