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Biomedical subjects

L J Kricka

Publications and source records attributed to L J Kricka.

At least 109 records · Page 6Linked to original sources
PubMed1985

Phenols as enhancers of the chemiluminescent horseradish peroxidase-luminol-hydrogen peroxide reaction: application in luminescence-monitored enzyme immunoassays.

Certain phenol derivatives, including p-iodophenol and p-phenylphenol, enhance light emission from the horseradish peroxidase-catalyzed oxidation of cyclic diacyl hydrazides such as luminol. The light emission decays slowly (glowing for several minutes) and its intensity may be greater than 1000-fold that of the unenhanced reaction. The enhanced system enables rapid, sensitive assay of peroxidase conjugates. We describe its application in immunoassays for human choriogonadotropin, digoxin, and factor VIII-related antigen. Luminescent quantification of peroxidase labels has been directly incorporated into immunoassays based on beads, tubes, or microtiter plates, used in conjunction with photodetectors such as photomultiplier tubes or instant photographic film. Enhancement with phenol derivatives exceeds that achieved with 6-hydroxybenzothiazole derivatives and depends on pH and enhancer concentration. Emission spectra of phenol-enhanced and unenhanced reactions are remarkably similar, suggesting that the enhancers do not act as more efficient emitters but exert their action earlier in the complex reaction between peroxidase, oxidant, and luminol.

Antigens↗
PubMed1984

Enhanced luminescent enzyme immunoassays for rubella antibody, immunoglobulin E and digoxin.

A novel firefly luciferin- enhanced luminescent procedure for the quantitation of horseradish peroxidase labels has been directly incorporated into established enzyme immunoassays. The procedure is rapid and sensitive and uses readily available reagents. Light emission from the enhanced reaction is high and relatively constant and thus easily measured. The luminescence procedure has been successfully incorporated into immunometric assays for rubella antibody and human IgE and into a competitive immunoassay for digoxin.

Animals↗
PubMed1984

An enhanced chemiluminescence enzyme immunoassay for serum progesterone.

A competitive enhanced luminescent enzyme immunoassay for serum progesterone is described, which is based on a 11 alpha-hydroxyprogesterone 11-hemisuccinyl-horseradish peroxidase conjugate and a black polystyrene microtitre plate sensitised with anti-progesterone IgG. Bound label was determined using a mixture of 4-iodophenol, luminol and peroxide, and the light emitted from the wells of the plate quantitated using a luminescent plate reader. The assay was sensitive (detection limit 0.5 pg), precise (CV 2.7 - 9.0% in the concentration range 4.3-67.7 nM) and showed good correlation (r = 0.99) with a conventional radioimmunoassay.

Horseradish Peroxidase↗
PubMed1984

Iron deficiency in a Northern Thai population: the effects of iron supplements studied by means of plasma ferritin estimations.

Iron deficiency is a common problem, particularly in developing countries, but traditional laboratory methods of detecting this condition are unreliable. The prevalence of iron deficiency in a Northern Thai population (pre-school, school children, adult women) has been assessed by means of plasma ferritin concentrations. The results were compared with prevalences based on blood haemoglobin concentrations. Estimations of prevalences based on plasma ferritin values were 10-24% in non-vegetarian and 49-71% in vegetarian groups, whilst those based on blood haemoglobin were 11-21% (non-vegetarian) and 24-50% (vegetarian). Dietary supplementation with iron produced dramatic rises in plasma ferritin in all of the groups studied. The effects on blood haemoglobin concentration and haematocrit were less marked. These results highlight the extent of iron deficiency in a Thai population and demonstrate the sensitivity of plasma ferritin as a test for detecting this condition and assessing the response to dietary supplementation.

Adolescent↗
PubMed1984

Effects of changes in dietary sodium intake on normotensive subjects with and without a genetic predisposition to essential hypertension.

Twenty-two young normotensive male subjects, 12 with an established family history of essential hypertension, were put on a low-followed by a high-sodium diet. Plasma from each dietary period was tested for inhibitory activity on Na-K-ATPase using three different techniques: measurement of 22Na efflux rate, measurement of 3H ouabain binding characteristics and a bioluminescent adenosine triphosphate assay. The high-sodium diet was associated with a diminished ouabain-sensitive sodium efflux rate constant in the whole group; however, no circulating inhibitor could be detected in the plasma. Those with and those without a family history of essential hypertension were indistinguishable. The results suggest that young normotensive individuals with a genetic predisposition to essential hypertension do not produce a circulating inhibitor of sodium-potassium adenosine triphosphatase (Na-K-ATPase) in response to a high-sodium challenge.

Adenosine Triphosphate↗
PubMed1984

Acetaldehyde-hemoglobin adducts: an unreliable marker of alcohol abuse.

Acetaldehyde reacts with hemoglobin in vitro to produce acetaldehyde-hemoglobin adducts, but we could not detect these in the blood of 20 alcoholics, either by cation-exchange chromatography or agar gel electrophoresis. Thus, contrary to previous reports, this test is not a reliable marker of alcohol abuse. Nuclear magnetic resonance and gas chromatographic-mass spectroscopic analysis of acetaldehyde revealed the presence of aldehydic impurities. Formation of adducts in vitro may thus result from the reaction of hemoglobin with these impurities or with acetaldehyde condensation products (aldol) or from acetaldehyde condensation/dehydration products (crotonaldehyde).

Acetaldehyde↗
PubMed1983

Coimmobilized multienzymes: an in vitro model for cellular processes.

Two different systems of multienzymes have been coimmobilized onto Sepharose and shown to be catalytically active. The first system consists of the five enzymes that catalyze the conversion of glucose 1-phosphate to 1,3-diphosphoglycerate along with the bacterial enzymes which are used to monitor NADH production by light emission. The NADH:FMN oxidoreductase-luciferase enzymes act to "pull" the reactions by continually oxidizing the NADH formed. The second system consisted of the 11 enzymes necessary for the conversion of glucose to alcohol and the bacterial enzymes. In the presence of excess glucose this immobilized system was able to produce 4068 nmol of alcohol per gram of Sepharose-enzymes in 4 h. Using the same system, if 3-phosphoglycerate was used as the substrate, 6552 nmol of alcohol were formed. These multienzyme immobilized systems are models that are uniquely suited for comparative studies of metabolic processes that occur in intact cells.

Animals↗
PubMed1983

Automated bioluminescent assays for NADH, glucose 6-phosphate, primary bile acids, and ATP.

An automated flow system for the bioluminescent assay of various metabolites have been developed. The enzymes used in the assays have been coimmobilized onto Sepharose and packed into small flow cells. Assays for NADH, glucose 6-phosphate, and primary bile acids utilize the bacterial NADH:FMN oxidoreductase/luciferase and either glucose-6-phosphate dehydrogenase or 7 alpha-hydroxysteroid dehydrogenase. ATP assays were performed using immobilized firefly luciferase. In general, the lower limit of detection of the metabolites was at the picomole level, and light intensity was proportional to the substrate concentration from several picomoles to several hundred picomoles. The reproducibility was good with coefficient of variations in the range of 2-5%. The carryover was less than 5% and 30 samples per hour could be assayed. The flow cells were reusable for up to 700 consecutive assays. The major factor limiting their continued use was bacterial contamination of the Sepharose. The results obtained for serum primary bile acids using the bioluminescent assay wer in good agreement with independent measurements on the same samples using gas-liquid chromatography. The immobilized firefly luciferase system was successfully used to measure high levels of bacteria in urine specimens.

Adenosine Triphosphate↗
PubMed1982

Ultrathinfilm immunoelectrophoresis.

Immunoelectrophoresis (Laurell-rocket) in ultrathinfilm gels has been applied to the determination of human serum albumin in a model study. Agarose gels of 0.24 mm thickness were used and optimum electrophoretic conditions were determined. Precision was assessed and comparison with conventional immunoelectrophoresis and a chemical method was made. Though precision was poor (CV 4-6%) improvements in dispensing small volumes (0.2 microliter) should change this. Good correlation between methods (correlation coefficient 0.89-0.97) was obtained. The advantages of the technique are speed of analysis and low reagent costs.

Blood Protein Electrophoresis↗
PubMed1982

Bioluminescence measurement of primary bile acids using immobilized 7 alpha-hydroxysteroid dehydrogenase: application to serum bile acids.

A simple, rapid, and sensitive bioluminescence method for measuring primary bile acids has been developed and validated. The method is based on enzymatic dehydrogenation of bile acids using a bacterial 7 alpha-hydroxysteroid dehydrogenase that is co-immobilized on Sepharose 4B beads with NADH:FMN oxidoreductase and a bacterial luciferase. The assay is specific for 7 alpha-hydroxy bile acids and has a detection limit of 0.5 pmol/tube, with a linear range of 0.5-50 pmol/tube. The assay shows good precision (6-8% intra-assay; 8-10% inter-assay). The values obtained with the bioluminescence assay showed good agreement with those obtained by gas-liquid chromatography, radioimmunoassay, or endpoint enzymatic assays. When applied to the measurement of serum bile acids, there was no interference from serum albumin, and the effect of other dehydrogenase activity in serum could be eliminated by heating the sample prior to assay. Since the method is rapid (1 minute), extremely sensitive (requires only 10 microliters of serum), and specific, it appears to be the best method currently available for the measurement of serum primary bile acids.

Bile Acids and Salts↗