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C Riley

Publications and source records attributed to C Riley.

At least 55 records · Page 3Linked to original sources
PubMed1983

Use of Lucifer yellow VS as a label in fluorescent immunoassays illustrated by the determination of albumin in serum.

The use of a new label for fluoroimmunoassay is described. Lucifer yellow VS is a highly fluorescent vinyl sulphone dye which, under mild conditions, forms covalent bonds with amino and sulphydryl groups but is extremely stable in water. A large Stokes shift (110 nm) and an emission maximum at 540 nm give Lucifer yellow further advantages over the more commonly used labels. The use of the dye as a label has been demonstrated by developing a heterogeneous fluoroimmunoassay for human serum albumin. The fluoroimmunoassay gave comparable results to those obtained using a less specific colorimetric dye-binding assay (r = 0.97, n = 20). The advantages, limitations, and other potential uses of Lucifer yellow are discussed.

Colorimetry↗
PubMed1983

Controlled dispersion analysis: flow-injection analysis without injection.

Flow-injection analysis is a precise, elegant, and economical technique, but its most troublesome feature is the mode of injection of the sample slug. We describe an alternative approach in which the sample is aspirated by the sample probe. In the simplest version the probe normally rests in reagent; when sampling is to take place, the pump is stopped and the probe is transferred to the sample container. The pump makes a predetermined angular movement, the probe is returned to reagent, and the pump is restarted. In more advanced versions the same approach is combined with the merging zone technique. The system is economical, precise, and capable of full automation in a multichannel discretionary analyzer.

Autoanalysis↗
PubMed1982

Zinc and copper determination in microsamples of serum by flow injection and atomic absorption spectroscopy.

A new approach to the direct determination of copper and zinc in serum and plasma is described. The sample is injected into a continuously pumped stream of water which is fed into the nebuliser of an atomic absorption spectrophotometer. Analytical results are obtained as a series of sharp peaks on a chart recorder. Analytical variables have been investigated, and the proposed method gave results comparable to those obtained using a conventional method based on precipitation of serum proteins with trichloroacetic acid. The proposed method takes less time to perform and was found to give more precise results than the conventional method. In addition, the flow injection analysis method can be performed using microsamples (10-100 microliters) and is thus ideally suited for use on children.

Copper↗
PubMed1982

FLow-injection analysis: a new approach to quantitative measurements in clinical chemistry.

Flow-injection analysis, founded on an approach that is entirely different from continuous-flow analysis, involves use of three principles: sample "injection," controlled dispersion of sample (rather than a dispersion retarded with gas bubbles), and reproducible timing. The conditions governing the dispersion of the sample in the flowing carrier stream are considered, and we illustrate how the dispersion can be manipulated to suit particular analytical requirements. Instrumentation and practical aspects of flow-injection analyses are discussed, especially with regard to clinical chemistry applications, and the technique is compared with the more conventional gas-segmented-flow analysis system. We conclude that, because of its speed, economy, and simplicity, flow-injection analysis will eventually replace the gas-segmented approach for many clinical chemistry analyses.

Chemistry, Clinical↗
PubMed1982

Simultaneous enzyme immunoassay of two thyroid hormones.

We describe an enzyme immunoassay in which the two thyroid hormones, triiodothyronine and thyroxin, are measured simultaneously in a single tube. The method involves labeling the two with separate enzymes (beta-galactosidase and alkaline phosphatase, respectively), whose catalyzed reactions can easily be distinguished from each other by absorption spectrophotometry, with o-nitrophenyl-beta-galactoside and phenolphthalein monophosphate as substrates. Performance of this dual assay method compares well with that of conventional single-hapten enzyme-labeled assays, and results compare well with those by two single-hapten radioimmunoassays. The dual assay has certain advantages over single-hapten methods: smaller sample volume, lower reagent cost, and shorter overall assay time. As presented here, the use of enzyme labels to measure two (or more) haptens simultaneously represents a significant advance in the use of immunoassay techniques.

Humans↗
PubMed1982

Direct determination of therapeutic concentrations of lithium in serum by flow-injection analysis with atomic absorption spectroscopic detection.

In this flow-injection system for direct determination of lithium in serum by atomic absorption spectroscopy, the 10-microL sample is manually injected into a continuously flowing non-segmented stream of de-ionized water, which is pumped, via a dispersion tube, to the spectrometer's nebulizer. Controlled dispersion of the sample zone, before it is introduced into the nebulizer, produces the required sample dilution. Effects of varying the length of the dispersion tube, the flow rate, and the sample size were studied. Analytical readout is obtained, in the form of transient peaks, 5 s after sample injection. It is necessary to include physiological concentrations of sodium and potassium in the standard because each of these cations enhances the lithium absorbance signal. Analytical recovery (98.5 to 101%) and CV (about 2%) are good, and results compare well with those obtained by aspiration of prediluted samples (n = 121, r = 0.99).

Chemistry, Clinical↗
PubMed1979

Ileostomy reconstruction.

A study of 47 patients undergoing ileostomy reconstruction is presented. The most common indications were recession (15 patients) and a desire for a continent type of ileostomy (12 patients). Less frequent indications were stenosis (6 patients), parastomal ulceration (6 patients), prolapse (4 patients), unsatisfactory siting (3 patients), and parastomal hernia (1 patient). Refashioning of the ileostomy at the same site was possible in 17 patients, whilst repositioning at a new site was required in 30 cases. In 28 of these laparotomy was carried out to enable repositioning, but in two cases resiting was performed without laparotomy. After the original operation, reconstruction may become necessary at any time from a few months to over 20 years.

Adolescent↗
PubMed1977

Effect of structure on the excretion of steroidal acids in human urine and their potential colorimetric assay as 17-oxogenic steroids.

Following the oral administration of tritiated coricosterone, cortisol, deoxycorticosterone and progesterone to human subjects, 14.9%, 12.8%, 3.4% and 2.1% of the dose was recovered in the acidic metabolite fraction of 48 h urines after conventional hydrolysis and solvent partition. Neutral and acidic 17-oxogenic steroids (17-OGS) excreted in 24 h urines were also measured with the Zimmermann color reaction. The acidic 17-IGS accounted for 14.1%, 16.4% and 12.1% of the fractionated 17-OGS in the urines of normal and pregnant females and normal males respectively. From structural considerations, it was concluded that only 17-hydroxylated steroidal acids, with a 20-hydroxy-21-oic acid side chain and derived predominantly from cortisol, would be estimated as 17-OGS after oxidation with sodium periodate. 17-Dexy steroidal acids resemble the neutral 17-deoxycorticosteroids in undergoing side chain oxication to 17-aldehydes which do not form Zimmermann chromogens. The excretion of both neutral and acidic 17-OGS was suppressible with dexamethasone administration.

17-Ketosteroids↗