Biomedical subjects

W E Neeley

Publications and source records attributed to W E Neeley.

35 records · Page 2Linked to original sources

PubMed1982

Fetal hemoglobin: optimum conditions for its estimation by alkali denaturation.

Alkali denaturation is the most commonly used technic to estimate fetal hemoglobin in red blood cells. The Betke and colleagues method (Nature 184: 1959; 1877-78) using cyanmethemoglobin (HiCN) was recommended by an International Committee for Standardization in Hematology for fetal hemoglobin levels between 2 and 40%. We showed that precision with samples containing up to 5% fetal hemoglobin can be considerably improved by measuring the absorbance of HiCN at 420 nm rather than at 540 nm because the molar absorptivity is 10 times greater in the Soret band. To determine optimum conditions for the assay, we studied the kinetics and stoichiometry of conversion of hemoglobin to HiCN with various concentrations and mixtures of ferricyanide, kinetics of alkali denaturation, ammonium sulfate precipitation of denatured HiCN, filtration as opposed to centrifugation for separating denatured HiCN, stability of HiCn in water and KCN solutions, and linearity of absorbance in the Soret band. With our modified procedure, the CV with normal amounts (less than 1%) of fetal hemoglobin improved from 28% to 8.7%. The CVs with 6.8% and 55% fetal hemoglobin were 7.0-4.4% respectively, and linear estimates were obtained with cells containing up to 50% fetal hemoglobin. We conclude that our modified alkali denaturation procedure yields reliable and reproducible estimates of fetal hemoglobin over a wide range of concentrations.

Adult↗

PubMed1981

An instrument for digital matrix photometry.

A new instrument was conceived and designed for quantitative measurement of chromophoric areas or colored spots such as are produced in (e.g.) thin-layer chromatography. The areas to be measured are subdivided grid-like into small subunits, and the absorbance of each of these is measured. The sum of absorbances for all subunits is directly proportional to the total amount of light-absorbing substances in a spot. The absorbances of the subunits are measured with a photodetector that contains hundreds of microscopically small photodiodes, arranged in a precise geometric array. The photodiode array is interfaced with a computer via an analog-to-digital converter for numerically integrating the individual signals from each photodiode. With this analytical system, quantitation of light-absorbing substance is accurate and precise for areas of different sizes, shapes, and internal irregularity.

Chromogenic Compounds↗

PubMed1977

Determination of "true" serum creatinine by high-performance liquid chromatography combined with a continuous-flow microanalyzer.

We coupled a high-performance liquid chromatograph with a continuous-flow microanalyzer to produce a system for specifically determinig "true" creatinine in urine and serum specimens. A selective microbore pellicular cation-exchange column and a single eluting sodium citrate buffer are used to separate the noncreatinine but Jaffé-positive constituents from the creatinine in normal and experimental specimens. The effluent is analyzed continuously, on-line, the alkaline picrate complex being developed and measured in the microanalyzer. Physiological samples, reference standards, and internal control specimens are assayed in 6-min intervals subsequent to the initial injection. The relationship between concentration and peak are is linear for creatinine standards between 5 and 10 mg/liter. Specimen volumes ranging from 1 to 25 microliters, and containing creatinine in amounts exceeding 5 ng per injected sample, can be assayed with this system.

Chromatography, High Pressure Liquid↗

PubMed1976

High-performance colorimeter with an electronic bubble gate for use in miniaturized continuous-flow analyzers.

We describe a high-performance colorimeter with an electronic bubble gate for use with miniaturized continuous-flow analyzers. The colorimeter has a flow-through cuvette with optically flat quartz windows that allows a bubbled stream to pass freely without any breakup or retention of bubbles. The fluid volume in the light path is only 1.8 mul. The electronic bubble gate selectively removes that portion of the photodector signal produced by the air bubbles passing through the flow cell and allows that portion of the signal attributable to the fluid segment to pass to the recorder. The colorimeter is easy to use, rugged, inexpensive, and requires minimal adjustments.

Autoanalysis↗

PubMed1975

Improved direct colorimetric method for the determination of total serum globulins.

1. A direct, fast, and efficient manual method is described for determining total serum globulins. The procedure is based on the reaction of tryptophan residues with glyoxylic acid in the presence of an oxidizing agent to produce a highly colored 4-carboline derivative. 2. A single, odorless reagent is employed and Beer's law is obeyed up to at least 7 g/100 ml of globulin at 565 nm. 3. Results of parallel assays demonstrate good agreement between our method and a reference cellulose acetate electrophoretic method and poor agreement with a HABA dye binding method.

Azo Compounds↗

PubMed1975