Chemiluminescence assay of serum alkaline phosphatase and phosphoprotein phosphatases.
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Alkaline Phosphatase↗
Biomedical subjects
B J Hallaway
Publications and source records attributed to B J Hallaway.
Chemiluminescence screening assays for erythrocytes and leukocytes in urine.
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Erythrocytes↗
A laboratorian's perspective on evaluation and implementation of new laboratory tests.
New assay development should be directed toward answering fundamental clinical questions. Caveats that must be considered before initiating assay development projects are: New assays should allow the clinician to interact with and treat a patient more effectively, thereby improving medical outcome; and new assays should facilitate recapture of system resources, enabling cost savings or reinvestment of resources. Defining the clinical questions and consideration of the caveats permit a means of prioritizing assay development activities. Laboratorians are faced with evaluating several types of development activities that lead to assay implementation in routine clinical testing. Assays can be prioritized for up-grading to newer cost-effective technologies, provided the changes maintain or improve analytical and clinical performance. Predicting which research assay will have future value is difficult when clinical performance is not fully validated. However, such assay development has the greatest potential for changing the delivery of healthcare by a clinician.
Biomarkers↗
HDL subparticles and coronary artery disease in NIDDM.
Decreased HDL cholesterol levels are associated with an increased risk of coronary artery disease (CAD) in non insulin dependent diabetes mellitus (NIDDM). The aim of this study was to compare HDL subparticles with apo A-I (LpAI) and those with apo A-I and apo A-II (LpAI/AII) in subjects with and without NIDDM and to study the relationship between HDL subparticles and CAD in NIDDM. Lipids, apo A-I and HDL subparticles were measured in 240 subjects with NIDDM and in 248 age and gender matched controls. Subjects with NIDDM had higher triglyceride levels (2.5 +/- 1.8 vs. 1.4 +/- 0.8 mmol/1, P < 0.001), lower HDL cholesterol (0.9 +/- 0.3 vs. 1.2 +/- 0.3 mmol/l, P < 0.001), apo A-I (124.7 +/- 22.4 vs. 139.8 +/- 24.1 mg/dl, P < 0.001) and LpAI/AII (82.4 +/- 18.2 vs. 94.9 +/- 16.7 mg/dl, P < 0.001) in comparison to controls. LpAI levels were similar in both groups. Diabetic subjects with CAD (n = 109) had higher triglycerides (2.7 +/- 1.9 vs. 2.3 +/- 1.8 mmol/l, P = 0.02) and lower HDL cholesterol (0.8 +/- 0.2 vs. 1.0 +/- 0.3 mmol/l, P <0.001), apo A-I (115.5 +/- 20.1 vs. 132.3 +/- 21.4 mg/dl, P < 0.001), LpAI (40.2 +/- 9.1 vs. 44.4 +/- 12.4 mg/dl, P = 0.06), and LpAI/AII levels (75.4 +/- 18.0 vs. 88.3 +/- 16.2 mg/dl, P < 0.001) in comparison to diabetic subjects without CAD (n = 131). In a multivariate analysis, apo A-I was found to be the best predictor of CAD in subjects with NIDDM. In conclusion, reduced HDL cholesterol levels found in NIDDM are, principally, due to reduced concentrations of apo A-I and apo A-II-containing particles (LpAI/AII). While LpAI and LpAI/AII levels were lower in NIDDM subjects with CAD, plasma apo A-I is the best predictor of CAD in NIDDM.
Aged↗
The role of lipoprotein A-I and lipoprotein A-I/A-II in predicting coronary artery disease.
The aim of this study was to examine the role of HDL subparticles with apolipoprotein (apo) A-I alone (LpA-I) and with apoA-I and apoA-II (LpA-I/A-II) in predicting coronary artery disease. Concentrations of these HDL subparticles were compared in 184 subjects with angiographically confirmed significant coronary artery disease (> 50% stenosis of at least one vessel) and 191 age- and sex-matched control subjects without clinical coronary artery disease. LpA-I and LpA-I/A-II were measured with magnetic beads coated with anti-apoA-II antibodies to separate particles containing apoA-II from plasma. Total plasma cholesterol and triglyceride levels were similar in both groups. Although subjects with coronary artery disease had lower HDL cholesterol, plasma apoA-I, LpA-I, and LpA-I/A-II than age- and sex-matched control subjects without coronary artery disease, plasma apoA-I was the best predictor of coronary artery disease. In conclusion, LpA-I and LpA-I/A-II are lower in subjects with coronary artery disease but do not add to plasma apoA-I in predicting the presence of coronary artery disease.
Aged↗
Immunomagnetic separation of subpopulations of apolipoprotein A-I.
OBJECTIVE: This study was undertaken to measure the subfractions of high-density lipoprotein (HDL) in patients with diabetes or coronary artery disease and in normal control subjects. DESIGN: A new immunomagnetic separation technique was used to characterize the lipid profile in four groups: (1) control subjects, (2) patients with diabetes but no coronary artery disease (CAD), (3) those with CAD only, and (4) those with both diabetes and CAD. MATERIAL AND METHODS: To study the individual roles of the two discrete HDL subpopulations of particles--LpAI/AII (apolipoprotein [apo] A-I associated with A-II) and LpAI (apo A-I without A-II)--in lipoprotein metabolism, we developed an immunomagnetic separation technique using magnetic beads coated with antibodies to human apo A-II. The beads bind particles that contain both apo A-II and apo A-I and are precipitated by a magnetic field. LpAI levels were measured in the supernatant by performing an apo A-I radioimmunoassay. LpAI/AII levels were determined by subtracting the LpAI levels from total plasma apo A-I. RESULTS: In comparison with control subjects, patients with diabetes, CAD, or both had significantly decreased levels of LpAI/AII. LpAI levels were normal in patients with diabetes without CAD but significantly lower than control values in those with diabetes and CAD. CONCLUSION: Our findings suggest that both subpopulations of HDL particles have implications in the development of atherosclerosis in patients with and without diabetes.
Adult↗
Separation of high-density lipoproteins into apolipoprotein E-poor and apolipoprotein E-rich subfractions by fast protein liquid chromatography using a heparin affinity column.
The aim of this paper is to describe a new methodology for the separation of human high-density lipoproteins (HDL) into apolipoprotein (apo) E-poor and apo E-rich subfractions by fast protein liquid chromatography (FPLC) using a heparin affinity column. Recoveries for apolipoproteins AI, AII, CI, CII, CIII, and E were 68.9, 74.7, 71.9, 73.5, 40.0, and 55.8%, respectively. We provide suggestive evidence that apo E-rich HDL is produced from apo E-poor HDL by the displacement of apo AI by apo E. Apo E-poor HDL was the predominant fraction. The molar ratio of apo E to apo AI in apo E-poor HDL was 0.02 and 0.01 for the subjects studied while in apo E-rich HDL it was 1.86 and 1.25. The molar ratios of the C apolipoproteins to apo AI are markedly different between the subfractions.
Apolipoproteins↗
Apolipoprotein B quantified by particle-concentration fluorescence immunoassay.
We have developed a particle-concentration fluorescence immunoassay (PCFIA) for estimating apolipoprotein (apo) B concentrations in plasma. A two-step antigen-detection system with a polyclonal antibody to apo B bound to carboxyl-polystyrene particles binds the antigen, and a fluorescein-labeled monoclonal antibody detects the bound apo B. Narrow-cut low-density lipoproteins (d = 1.03-1.05 kg/L) were used as the primary standard. The assay compares well with the enzyme-linked immunosorbent assay. The PCFIA gives parallel responses with low-density lipoprotein, very-low-density lipoproteins, and plasma samples, and can be fully automated and completed in 3 h. In a pilot study of patients with diabetes, coronary artery disease (CAD), or both, we found statistically significant differences in apo B concentrations for patients with both CAD and diabetes compared with those for patients with diabetes alone or for control subjects (P < 0.01).
Apolipoproteins B↗
Apolipoproteins and coronary artery disease.
In this study, we compared the relative utility of plasma levels of cholesterol, triglycerides, high-density lipoprotein (HDL) cholesterol, and apolipoproteins in identifying men with angiographically significant coronary artery disease in a combined sample of consecutive male patients undergoing coronary angiography (N = 304) and healthy, normal male control subjects (N = 135). The plasma apolipoprotein levels were measured by using specific radioimmunoassays. We found that plasma levels of apolipoprotein A-I, followed by those of apolipoproteins A-II and B, were better discriminators than plasma cholesterol, triglycerides, or HDL cholesterol levels for identifying those with coronary artery disease. In confirmation of previous findings, the presence of coronary artery disease resulted in lower levels of apolipoproteins A-I and A-II and HDL cholesterol and higher levels of apolipoprotein B, cholesterol, and triglycerides. Linear and quadratic discriminant function analysis demonstrated that by using the age of the patients and apolipoprotein A-I, A-II, and B levels, one could correctly classify patients either as being normal or as having angiographically significant coronary artery disease in more than 75% of the cases. Thus, plasma apolipoprotein levels (especially A-I and A-II) may be considerably better markers for coronary artery disease than traditional lipid determinations.
Adult↗
Use of a quality-control plasma sample to decrease interassay variation in radioimmunoassays of apolipoprotein A-I.
The apolipoprotein A-I (apo A-I) radioimmunoassay established in our laboratory involves use of purified apo A-I as the primary standard for quantifying apo A-I in plasma and a pooled plasma (quality-control sample) as a secondary standard to decrease interassay variation. The measured values for apo A-I increased over time as the labeled antigen degraded. We observed these results in two separate studies: (a) apo A-I in plasma from 16 subjects was measured 12 times during four months, and (b) apo A-I in a single pooled plasma was measured 48 times during 10 months. We show that use of a quality-control plasma sample as a secondary standard decreased interassay variation, which was, in part, ascribable to degradation of the labeled antigen.
Adult↗