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Biomedical subjects

E M Brosious

Publications and source records attributed to E M Brosious.

8 recordsLinked to original sources
PubMed1979

Quantitation of hemoglobin A2. An interlaboratory study.

In the 1976 hemoglobinopathy proficiency testing survey of the Center for Disease Control (CDC), whole-blood samples from hematologically normal adults and from individuals heterozygous for beta-thalassemia were shipped to survey participants. The object of this survey was to determine the state of the art for technics used to quantitate hemoglobin A2 (Hb A2) and to test the ability of laboratories to differentiate between blood samples having normal Hb A2 levels and those having elevated levels (i.e., those from individuals with beta-thalassemia trait). The results of Hb A2 quantitation obtained from 183 volunteer participant laboratories were compared with those obtained from 24 reference laboratories. Individual values varied greatly among laboratories and among methods for both normal and elevated Hb A2 samples. The results returned by many laboratories were not within 2 SD of the reference laboratory mean and also were not sufficiently accurate to differentiate between the normal blood samples and those with beta-thalassemia trait. The results suggest that methods for quantitating Hb A2 need to be standardized and a suitable method for determining laboratory performance found.

Blood Chemical Analysis↗
PubMed1979

Quantitation of hemoglobin F. An interlaboratory study.

Samples of whole blood from four hematologically normal adults and from two individuals with increased fetal hemoglobin levels were shipped to laboratories participating in the 1976 and 1977 Center for Disease Control (CDC) hemoglobinopathy proficiency testing surveys. The data from these surveys were used to evaluate the interlaboratory variability of current methods used to quantitate hemoglobin F (Hb F). Results of Hb F quantitation obtained from more than 100 laboratories than voluntarily participated in the survey were compared with those obtained from 21 reference laboratories. Individual values for all samples varied greatly among laboratories and among methods. Results returned by most of the laboratories were outside two standard deviations of the reference laboratory mean and were not accurate enough to differentiate between a normal level and an increased, abnormal level.

Fetal Hemoglobin↗
PubMed1978

Microchromatographic methods for hemoglobin A2 quantitation compared.

On 20 consecutive work days during four weeks, one technologist performed 24 microchromatographic determinations of hemoglobin A2 (Hb A2) by each of four methods: the Efremov procedure requiring Tris/HCl buffer, the original Huisman technique with use of glycine developer, and two commercial test kits in which a modified glycine developer is used. The bloood samples tested were obtained from 12 adults with no hematological abnormality and from 12 beta-thalassemia carriers previously diagnosed by familial and hematologic studies. Results by the first method and the two commercial kits (one from Helena Laboratories and one from Isolab, Inc.) did not differ significantly in precision for either the normal or beta-thalassemia trait samples. For both sample types, the second method yielded larger coefficients of variation than those obtained with the other methods. Moreover, the second method was the only one with which values overlapped for normal samples and samples with above-normal Hb A2 concentrations.

Chromatography, Ion Exchange↗
PubMed1977

Preparation and use of a quality control hemolysate for microchromatographic determinations of hemoglobin A2.

Compared with other methods for determining hemoglobin A2 (Hb A2) levels, the new microchromatography procedures are fast, easy laboratory technics useful for quantitating Hb A2 that can be readily monitored for quality control of results. A reliable method for preparing a stable hemolysate control for monitoring the accuracy and precision of Hb A2 microchromatographic procedures is described. The recombination of purified hemoglobin fractions in known concentrations and the addition of potassium cyanide and carbon monoxide produce a control solution that gives stable hemoglobin A2 values for at least 40 weeks. Variability among six reference laboratories was small.

Chromatography↗
PubMed1976

Effects of hemoglobin F levels, KCN, and storage on the isopropanol precipitation test for unstable hemoglobins.

Although the isopropanol precipitation test is a commonly used and sensitive test for detecting unstable hemoglobins, false-positive reactions are frequently observed. In this study, the storage temperature of the test samples, type of stored sample amount of fetal hemoglobin (Hb F) in the sample, and presence of potassium cyanide (KCN) in the hemolysate preparation all affected the accuracy of the test. The addition of 2% KCN to samples before testing eliminated or greatly reduced false-positive reactions. Hb F levels greater than 4% caused false-positive results. When specimens with Hb F levels less than 4% were stored at 4C and as whole blood, they showed no false-positive reaction for as long as two weeks. However, duplicate specimens stored as whole blood but unrefrigerated and those stored as hemolysates showed false-positive reactions after three days.

1-Propanol↗
PubMed1976

Use of blood specimens collected on filter paper in screening for abnormal hemoglobins.

Both cellulose acetate electrophoresis and citrate agar electrophoresis were performed on 834 blood samples collected on filter paper in Jamaica and shipped for testing to the National Hemoglobinopathy Standardization Laboratory at the U.S. National Center for Disease Control. Additionally, 30 blood samples collected locally were stored on filter paper, in microhematocrit capillary tubes, and as whole blood specimens; at selected times the samples were tested for stability to determine the best sample-collection technique for hemoglobin electrophoresis. Results were most nearly accurate when both cellulose acetate electrophoresis and citrate agar testing were used. The methods are easy to perform, but results are unreliable if the blood samples on filter paper are stored at 4 degrees C for longer than two weeks before they are tested.

Agar↗