Biomedical subjects

H Merrick

Publications and source records attributed to H Merrick.

4 recordsLinked to original sources

PubMed1990

A silicon sensor-based filtration immunoassay using biotin-mediated capture.

A sensitive sandwich immunoassay for human chorionic gonadotropin (hCG) was developed with biotin-mediated filtration capture and silicon sensor detection. A high density of biotin on the membrane assured efficient capture of complexes containing streptavidin and analyte. Capture efficiency was not affected over a wide range of filtration flow rates or biotin concentrations. The assay utilized the pH sensing ability of the light addressable potentiometric sensor (LAPS) for the detection of urease-antibody conjugates. A LAPS reader was constructed which allowed the enzyme conjugate to be detected in approximately 1 microliter volumes. Effects from variations in detection volume were studied. 10 pg of hCG could be detected in an assay time of 20 min with four standard deviations separation from background. Comparison to a commercial RIA was made.

Antibodies, Monoclonal↗

PubMed1990

Glucose metabolism and colorectal carcinoma.

We evaluated nine patients with colorectal cancer and six control patients in a postabsorptive state in an attempt to define the effect of cancer on glucose turnover, oxidation, recycling, and resting metabolic expenditures (RME). The glucose kinetics were determined using a double-labeled [U-14C] glucose and [6-3H] glucose, and energy expenditures were measured by indirect calorimetry. In addition, we also measured the same parameters in the cancer patient group on a total parenteral nutrition (TPN)-glucose system on the fourth day before and on the fifth day after removal of tumor. In the postabsorptive state, glucose turnover and oxidation rates were similar in the cancer and control group; however, the mean glucose pool size of the cancer group was 47% larger than the control group and was statistically significant (P = .05). Glucose recycling was also two times the control group and was statistically significant (P = .05). The recycling of glucose, both preoperatively and postoperatively, continued in the face of infused glucose; however, the rate was suppressed compared with the fasting cancer group. Postabsorptive RME of the cancer group did not differ from those predicted by the Harris-Benedict equation. Following a 4-day infusion of TPN-glucose that supplied a mean of two times the patients' energy needs, the preoperative cancer group showed a mean increase in RME of 25.6% and a 31.58% increase on the fifth postoperative day of TPN-glucose, presumably due to increased lipogenesis and to a much lesser extent from the increased protein synthesis (4 g positive N balance).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1987

An internal clock reaction used in a one-step enzyme immunochromatographic assay of theophylline in whole blood.

We describe the development and performance of a second-generation enzyme immunochromatography method for visually quantifying theophylline in whole blood without the use of instrumentation. We have developed the novel concept of an internal chemical clock reaction to combine the capillary-migration and color-generation protocol of the two-step immunochromatographic assay into a single-step, simultaneous protocol. The two assay components are (a) chromatographic paper to which glucose oxidase (EC 1.1.3.4) and monoclonal antibody to theophylline have been immobilized, and (b) an enzyme reagent consisting of glucose, dicarboxidine, ascorbate, and theophylline-labeled horseradish peroxidase (EC 1.11.1.7). The ascorbate acts as an internal clock by inhibiting premature color formation until the ascorbate has been completely consumed in the peroxidase-mediated reaction. Color is then generated rapidly, producing a clearly visible front on the paper. Performance evaluations of the 20-min one-step assay show very good precision, analytical recovery, specificity, and accuracy. This simplified protocol is reliable and convenient for therapeutic drug monitoring in the physician's office.

Antibodies, Monoclonal↗

PubMed1985

Enzyme immunochromatography--a quantitative immunoassay requiring no instrumentation.

We describe a novel test-strip immunoassay for quantifying drugs in biological fluids. This enzyme immunochromatographic ("immunograph") method combines many features of the enzyme-channeling homogeneous immunoassay with immunochromatography and capillary migration to provide a non-separation, non-instrumental assay for theophylline in which quantification is based on the spatial distribution of enzyme label rather than on the modulation of enzyme activity. Sample antigen and hapten-enzyme conjugate are combined and moved by capillary action up a paper strip on which specific antibody has been immobilized. After color development, the assay result is evaluated by measuring the height of the colored zone on the test strip. Quantification is not a function of enzyme activity, so the method is relatively insensitive to sample matrix effects, enzyme instability, temperature, and incubation timing. Either whole blood or plasma can be used as sample. Results correlate well with those by established instrumental methods. The simple, rapid (15 min), two-incubation protocol is well suited for on-site testing in non-laboratory environments.

Animals↗