Matrix effects in clinical analysis: commutability of control materials between the Ektachem, Beckman and SMA 12/60 glucose and urea methods

The effects of the protein matrices of selected human and animal based control materials on the Ektachem, Beckman and SMA 12/60 glucose and urea methods have been investigated by means of commutability studies. The commutability of control materials between the Ektachem and SMA 12/60 was greater than that between the Ektachem and Beckman methods and was similar to that reported for conventional methods. No trends were apparent amongst control sera from different species nor with different total protein levels. Some variation in commutability was found with different batches of Ektachem glucose and urea slides. In addition the effect of lyophilisation of fresh human serum on its analytical behaviour with different experimental batches of Ektachem glucose/urea slides was studied and found to be negligible.

Evaluation of the Kodak Ektachem glucose and urea methods

An evaluation of the Kodak Ektachem glucose and urea methods is described. Aspects evaluated included precision, linearity, accuracy, correlation with routine methods, interferences (haemoglobin, bilirubin, protein, dextran, lipaemia, ethylene-diamine tetraacetic acid, fluoride/oxalate, and heparin), and carryover. Stability and batch-to-batch variation in glucose and urea reagents were also investigated. The performance of the Ektachem glucose and urea methods was shown to be as satisfactory as conventional analytical methods. The requirement to reconstitute control serum samples in a bicarbonate diluent in order to obtain accurate results presents problems for the analysis of lyophilised specimens circulated by external quality assessment schemes. The complex calibration model and the significance of variation in the calibration parameters need further explanation. The Ektachem methods are designed specifically for use with human serum. However, the methods performed satisfactorily with cerebrospinal fluid, pleural effusions, and animal serum but not with urine.

Characterisation of the protein matrix of quality control sera by a high resolution two-dimensional electrophoresis technique

A high resolution two-dimensional electrophoresis technique (Iso-Dalt) has been employed to characterise the protein components of freshly drawn human serum and various human- and animal-based quality control sera. This technique allows a direct comparison to be made between the protein components of different materials. Similarities have been demonstrated between the protein components (protein matrix) of freshly drawn human serum and human-, equine- and bovine-based control sera, though some differences existed between sera from these three sources, mainly in the acidic high molecular weight quadrant and the lipoprotein and haptoglobin regions. The Iso-Dalt technique also revealed differences in the protein matrices of the various human-based quality control sera tested. Differences attributable to manufacturing technique were also discernible by inspection of the two-dimensional maps of the protein matrices. Although characterisation and comparison of protein components of the matrix of serum is difficult, the Iso-Dalt technique has proved a valuable tool in this characterisation and the subsequent assessment of the similarity of quality control sera to human serum. This type of information is valuable when considering the suitability of human- or animal-based sera for use in internal and external quality control procedures.

Comparison of urinary excretion of UV-absorbing constituents in healthy subjects and patients with rheumatoid arthritis using analytical isotachophoresis

Analytical isotachophoresis has been applied to the separation of urinary constituents in healthy controls and patients with rheumatoid and osteoarthritis. Various methods of comparing isotachograms have been investigated. Significant differences have been demonstrated between the pattern of UV-absorbing components in patients with rheumatoid arthritis and healthy subjects.

Pattern of urinary proteins and peptides in patients with rheumatoid arthritis investigated with the Iso-Dalt technique

Characteristic differences in the pattern of urinary proteins and peptides have been found in patients with rheumatoid arthritis, compared with patterns from healthy controls. These differences have been demonstrated with a two-dimensional gel electrophoretic technique (Iso-Dalt) involving isoelectric focusing in the first dimension, followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis in the second dimension. Using simple photographic techniques, one can obtain a composite pattern of the individual protein-stained gels for each group. Comparison of the composite patterns from the rheumatoid arthritis group and the control group revealed several proteins in the urine of the rheumatoid arthritis patients not found in the control group. Two groupings of these proteins were identified: acidic, high-Mr proteins and more basic, low-Mr proteins.

Pattern of urinary proteins and peptides in patients with rheumatoid arthritis investigated with the Iso-Dalt technique

Characteristic differences in the pattern of urinary proteins and peptides have been found in patients with rheumatoid arthritis, compared with patterns from healthy controls. These differences have been demonstrated with a two-dimensional gel electrophoretic technique (Iso-Dalt) involving isoelectric focusing in the first dimension, followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis in the second dimension. Using simple photographic techniques, one can obtain a composite pattern of the individual protein-stained gels for each group. Comparison of the composite patterns from the rheumatoid arthritis group and the control group revealed several proteins in the urine of the rheumatoid arthritis patients not found in the control group. Two groupings of these proteins were identified: acidic, high-Mr proteins and more basic, low-Mr proteins.

Pattern of urinary proteins and peptides in patients with rheumatoid arthritis investigated with the Iso-Dalt technique

Characteristic differences in the pattern of urinary proteins and peptides have been found in patients with rheumatoid arthritis, compared with patterns from healthy controls. These differences have been demonstrated with a two-dimensional gel electrophoretic technique (Iso-Dalt) involving isoelectric focusing in the first dimension, followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis in the second dimension. Using simple photographic techniques, one can obtain a composite pattern of the individual protein-stained gels for each group. Comparison of the composite patterns from the rheumatoid arthritis group and the control group revealed several proteins in the urine of the rheumatoid arthritis patients not found in the control group. Two groupings of these proteins were identified: acidic, high-Mr proteins and more basic, low-Mr proteins.

Mikulicz disease of a minor salivary gland

The third recorded instance of Mikulicz disease of a minor salivary gland is described; this is the first case in which a surgical specimen, in addition to the biopsy specimen, was obtained for microscopic examination. A brief description of the disease and its treatment is also presented.

Urinary metabolites of tryptophan, serotonin and norepinephrine in alcoholics

Levels of tryptamine, 3-methoxy-4-hydroxy phenylethylene glycol, 3-methoxy-4-hydroxy mandelic acid and the tryptamine: 5-hydroxyindole-3-acetic acid ratio differed between alcoholics, healthy volunteers and patients with nonalcoholic liver disease. There was no correlation between amine metabolite levels and results of liver function tests.