PubMed Health⌕ Search

Biomedical subjects

L J Kricka

Publications and source records attributed to L J Kricka.

At least 127 records · Page 7Linked to original sources
PubMed1981

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.

Autoanalysis↗
PubMed1981

Sensitive sandwich enzyme immunoassay for serum ferritin on microtitre plates.

A solid-phase sandwich enzyme immunoassay for serum ferritin is described. The assay procedure was simple, showed good precision, and was suitable for the routine determination of serum ferritin concentration in a clinical laboratory. The assay compared well with a conventional radioimmunoassay for ferritin. The assay was extremely sensitive and had a detection limit of 2.2pg.

Ferritins↗
PubMed1980

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.

Animals↗
PubMed1980

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.

Arthritis, Rheumatoid↗
PubMed1980

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.

Animals↗
PubMed1980

Variability in the adsorption properties of microtitre plates used as solid supports in enzyme immunoassay.

We evaluated the variability in the amount of protein adsorbed onto the surface of individual wells of an assortment of microtitre plates by use of procedures involving enzyme-protein conjugates. Coefficients of variation in adsorbed protein ranged from 5.2 to 29.5%. Microtitre plates show a distinct "edge effect"; wells at the edges of a plate adsorb more protein than those in the interior, which markedly affects results from immunoassays involving such plates. In a sandwich enzyme immunoassay the results for an individual sample varied by +/- 18%; in a competitive assay, values read from different calibration curves in the same plate varied by +/- 11%. Scanning electron microscopy and birefringence studies demonstrated no marked physical differences between individual wells on a plate. The variability in the amount of protein adsorbed onto the surface of individual wells on the same microtitre plate seriously affects the reliability and interpretation of results of immunoassays in which such plates are used as solid supports.

Alkaline Phosphatase↗
PubMed1980

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.

Arthritis, Rheumatoid↗
PubMed1979

Thermal characteristics of microtitre plates used in immunological assays.

Thermal studies of various types of microtitre plate have shown that wells at the edges of a plate have different thermal characteristics from those in the centre. This may contribute to the 'edge effect' observed when such plates are used as solid supports for protein immunobilisation in immunoassays.

Antigen-Antibody Reactions↗
PubMed1979

Spectral analysis of urinary reactions: a preliminary study based on a novel concept.

The concept of spectral analysis of urinary reactions (a range of simple chemical tests combined with pattern analysis) is described. A preliminary study in which we used 10 nonspecific tested on untimed urine specimens from 20 controls and 20 diabetics, matched for age and sex, suggested that a combination of these tests could be used to separate diabetics from healthy subjects. This combination, however, did not prove satisfactory for a further group of 13 diabetics. Closer examination revealed that factors such as therapy and glycosuria affected the results of these tests. This approach, which should extend the usefulness of urinalysis, may prove viable when larger groups, and possibly a different set of tests, are used to establish a more robust combination of tests.

Adult↗
PubMed1979

Analytical luminescence: its potential in the clinical laboratory.

The various types of chemiluminescent and bioluminescent reactions are described. Applications of luminescence in the analysis of substancs of clinical interest are surveyed. The advantages, disadvantages, and prospects for luminescent assays are discussed.

Adenosine Triphosphate↗
PubMed1978

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.

Adult↗
PubMed1977

A method for enhancing the stability of thiol-containing enzymes immobilised on nylon.

The limited stability of immobilised enzymes is a major factor restricting their use in clinical chemistry. The immobilisation procedure described here affords a simple method of enhancing the stability of certain enzymes immobilised on nylon. Studies with alcohol dehydrogenase and glyceraldehyde-3-phosphate dehydrogenase have indicated that a significant increase in stability can be obtained using this immobilisation procedure as compared with conventional procedures. As anticipated the immobilisation procedure was unsatisfactory for oxidases such as glucose oxidase.

Alcohol Oxidoreductases↗
PubMed1976

The application of thin-layer gel filtration chromatography in the rapid assessment of protein-protein coupling reactions.

The use of enzymes as markers when covalently coupled to various antigens or antibodies has wide application in medical science. A variety of bifunctional reagents has been used to produced the conjugates, and there have been some attempts to investigate the conditions of reaction necessary to obtain good coupling, whilst preserving the biological function of the molecules. The present study describes the influence of coupling conditions on the coupling of a alpha-amylase and albumin by a range of commercially available bifunctional coupling reagents, and the application of thin-layer gel filtration chromatography for the rapid qualitative/semi-quantitative assessment of coupling reactions.

Albumins↗
PubMedDate not supplied

Effect of enhancers on the pyridopyridazine-peroxide-HRP reaction.

4-Substituted phenyl boronic acids (e.g., 4-iodo, 4-bromo, 4-phenyl) are effective enhancers of the horseradish peroxidase (Type VIA) catalysed chemiluminescent oxidation of various pyrido[3,4-d]pyridazine-1,4(2H,3H)dione derivatives. The most effective combination was 4-biphenylboronic acid and 8-amino-5-chloro-7-phenylpyrido[3,4-d]- pyridazine-1,4(2H,3H)dione. Generally, the intensity of light emission in the presence of peroxidase was higher with the pyridopyridazines than with sodium luminol. However, the blank light emission was much lower with sodium luminol than with the pyridopyridazines. A synergistic enhancement phenomenon was demonstrated for the combination of a 4-iodophenol and a 4-biphenylboronic acid enhancer with 8-amino-5-chloro-7-phenylpyrido[3,4-d]pyridazine-1,4(2H,3H) dione. The combination of these two enhancers produced a light emission intensity in an assay for 5 fmol of peroxidase that was 25% higher than expected from the sum of the individual light intensities.

Boronic Acids↗