Analysis of the Albumin Cobalt Binding (ACB) test as an adjunct to cardiac troponin I for the early detection of acute myocardial infarction.

Human albumin has the ability to bind cobalt at the N-terminus. The exposure of circulating albumin to ischemic tissue alters the ability of albumin to bind cobalt, probably through a mechanism involving free-radical production. The Albumin Cobalt Binding (ACB) test measures the alteration in albumin metal binding, and elevation of the ACB test is thought to be an early indicator of myocardial ischemia. In a previous multicenter study of chest pain patients presenting to the emergency department (ED), this test demonstrated high negative predictive value and sensitivity in the sample collected at presentation for predicting cardiac troponin I (cTnI)-negative or cTnI-positive results 6-24 h later. Since the completion of that report, the European Society of Cardiology (ESC) and the American College of Cardiology (ACC) have redefined the criteria for the diagnosis of acute myocardial infarction (AMI). The data from the multicenter ACB study were re-examined using the new diagnostic criteria for AMI to determine if combining the ACB test with troponin improved the sensitivity of either assay used alone for early diagnosis of AMI. Assay values were compared to either the final discharge diagnosis made at each site or to a diagnosis of AMI using the strict application of the ESC/ACC guidelines. Using the criterion of physician's discharge diagnosis and using blood collected at ED presentation, the cTnI test alone had a sensitivity of 23.9%, and the ACB test alone had a sensitivity of 39.1%, but the sensitivity significantly increased to 55.9% (p < 0.001 over cTnI alone) when both tests were used in combination. The sensitivity of the combination of ACB and cTnI tests at the 1- to 6-h time-point was 86.7% and at the >6- to 12-h time-point was 93.5%, but they were not significantly improved over the cTnI test alone. In conclusion, using the new ESC/ACC criteria, the combination also resulted in a statistically significant higher diagnostic sensitivity on blood collected at presentation. These data indicate a possible role of the ACB test in the early triage of patients with chest pain.

Multicenter clinical and analytical evaluation of the AxSYM troponin-I immunoassay to assist in the diagnosis of myocardial infarction.

We evaluated the AxSYM troponin I (cTnI) immunoassay for assisting in the detection of acute myocardial infarction (AMI). At four sites, the total imprecision (CV) over 20 days was 6.3-10.2%. The minimum detectable concentration was 0.14 +/- 0.05 microgram/L. Comparison of cTnI measurements between the AxSYM and Stratus (n = 406) over the dynamic range of the AxSYM assay demonstrated good correlation, r = 0.881, with a proportional bias: AxSYM cTnI = 3.50(Stratus cTnI) - 1. 10. The confidence intervals (95%) for the slope and intercept were 3.39-3.64 and -1.32 to -0.95, respectively. The expected cTnI concentration in healthy individuals was /=96%, in skeletal muscle injury, chronic renal disease, and same-day noncardiac surgery patients.

Analytical evaluation and comparison of Dupont aca lactate dehydrogenase-1 (LD1) isoenzyme assay diagnostic efficiency for acute myocardial infarction detection with other LD1 methods and aca CK-MB. A two-site study.

The purpose of this study was to examine the analytical characteristics of a rapid new assay for lactate dehydrogenase 1 (LD1) isoenzyme on the Dupont aca analyzer and the diagnostic efficiency of LD1 for detection of acute myocardial infarction (AMI) when used alone and with creatine kinase MB (CKMB). Total aca LD1 assay precision, with percent coefficients of variation (%CVs) of less than 3.2% from 56 U/L to 469 U/L LD1, across fifty assay days was excellent. Linearity was confirmed from 0 to 332 U/L and no detectable calibration drift was noted from 5 to 489 U/L over a ninety-day period. The aca LD1 results compared well with Roche Isomune-LD1, Abbott Spectrum A-Gent, Helena electrophoresis, and Beckman electrophoresis LD1 methods, giving r's from 0.987 to 0.994, slopes from 0.94 to 1.65, and y-intercepts from -2.95 to 6.94 U/L. Examination of 450 ambulatory subjects, about equally distributed by sex, yielded a 43 +/- 14 U/L aca LD1 patient reference interval. Serum samples from 159 consecutive patients at the University of Tennessee Memorial Hospital and 96 patients at Allentown Hospital, submitted for AMI detection assistance, were assayed in a single-blind study for LD1 and ion-exchange CKMB by Dupont aca methods, which provide automated results in ten minutes whenever needed. The aca LD1 assay yielded a clinical sensitivity of 89% and specificity of 95% for AMI with a decision threshold of 120 U/L. The diagnostic efficiency of the aca LD1 assay was 94% at 120 U/L, which equaled or exceeded that of the three comparative LD1 methods. The predictive value of positive (PV+) and negative (PV-) results on the first sample collected were 80% and 85% for aca LD1, 65% and 90% for aca ion-exchange CKMB, and 83% and 90% when both tests were combined. Significantly, the PV+ and PV- results when two or more samples were assayed was improved to 88% and 95% for aca LD1, relatively constant at 65% and 97% for aca ion-exchange CKMB, and dramatically improved to 95% and 100% when both CKMB and LD1 tests were combined. The results from these two medical centers show that the aca LD1 assay provides useful clinical information for AMI diagnosis when employed alone or in combination with aca CKMB. These results also suggest that LD1 should be included in biochemical evaluations for AMI to attain optimal predictive values of results.

Lipoprotein lipid concentrations and cardiovascular risk in women with polycystic ovary syndrome.

Twenty-nine patients with polycystic ovary syndrome (PCOS) and 30 normal women had lipoprotein lipid and androgen profiles compared after a 12-h fast. Both PCOS and normal women were evaluated in the proliferative phase of the cycle. PCOS patients had higher serum LH to FSH ratios [2.0 +/- 1.3 (+/- SEM) vs. 0.6 +/- 0.1), higher testosterone (T; 66 +/- 5 vs. 33 +/- 2 ng/ml), higher free T (1.1 +/- 1 vs. 0.4 +/- 0.02 ng/dl), and higher dehydroepiandrosterone sulfate (291 +/- 28 vs. 140 +/- 12 micrograms/dl) levels, and lower T-estrogen-binding globulin-binding capacity (1.5 +/- 0.2 vs. 2.2 +/- 0.1 micrograms/dl) than normal women (all P less than 0.05). The PCOS patients had higher mean serum triglycerides [122 +/- 11 (+/- SEM) 63 +/- 3 mg/dl] and very low density lipoprotein cholesterol levels (24 +/- 2 vs. 13 +/- 1 mg/dl), but lower high density lipoprotein cholesterol levels (43 +/- 2 vs. 58 +/- 2 mg/dl; P less than 0.05). While PCOS patients were heavier and more sedentary and their diets were higher in saturated fat and lower in fiber (P less than 0.01, respectively), the differences in lipoprotein lipid concentrations could not be attributed to body weight. T-estrogen-binding globulin-binding capacity correlated with high density lipoprotein cholesterol in PCOS patients (r = 0.42; P = 0.025) after adjusting for weight. We conclude that hyperandrogenemia in women may result in a male pattern of lipoprotein lipid concentrations. These findings suggest that PCOS patients may have increased atherogenic potential.

Nucleotide and prostaglandin cycling in canine cyclic hematopoiesis.

Bone marrow cells were collected from normal dogs, normal dogs made neutropenic with cyclophosphamide, and 11 dogs affected with cyclic hematopoiesis (CH) on 3 consecutive days of separate 12- to 14-day cycles. The mononuclear marrow cells from both groups of control dogs and from the CH dogs on each of 12-cycle days were cultured for 2.5 hr in serum-free media. The amounts of prostaglandins (PGF2 alpha and PGE) and cyclic GMP (cGMP) measured in the media were found to vary with the cycle in the CH dog. PGF2 alpha was highest as the dogs recovered from the neutropenia and lowest 4 days before the onset of the next neutropenic episode. Cyclic GMP was lowest 4-5 days before the onset of neutropenia, then dramatically increased as the neutropenic period approached. Cyclic GMP was highest when PGF2 alpha was lowest. Normal dogs, made neutropenic with a single dose of cyclophosphamide, had elevations of PGF2 alpha but not PGE or cGMP during the recovery period of active granulopoiesis.

Amniotic fluid phosphatidylglycerol: a predictor of fetal lung maturity using conventional one-dimensional thin-layer chromatography.

We present a retrospective comparative analysis of 209 amniotic fluid samples and the neonatal outcome. The presence of phosphatidylglycerol in 159 transabdominal amniotic fluid samples and the associated lung status indicated a 98% prediction rate for absence of respiratory distress syndrome with 1.8% false-positive results corrected to 0%. Twenty-nine vaginal pool samples were 72% predictive of outcome with false-positive results corrected to 14%. These cases were mild, and if a phosphatidylglycerol level of greater than 3% is used to indicate lung maturity, the corrected false-positive rate is 0%. False-negative results are also corrected and discussed. We believe that predicting neonatal respiratory distress syndrome by phosphatidylglycerol determination, using readily available conventional one-dimensional thin-layer chromatography, is clinically reliable and can aid in determining the maturity of the lung regardless of site of fluid collection.

A rate nephelometric phenobarbital and phenytoin assay: analytical and correlation studies of a new single-point calibration immunoprecipitation inhibition method.

A new single-point calibration immunoprecipitation inhibition rate nephelometric assay for phenobarbital (PB) and phenytoin (PT) has been evaluated on the Beckman ICS-II analyzer. Within-run precision (n = 20) coefficients of variation (CV) were less than 4.0% for PB (10-44 micrograms/ml) and less than 5.7% for PT (12-34 micrograms/ml). Between-run precision CVs of pooled sera (n = 20) assay were less than 4.2% for PB (7.5-33.8 micrograms/ml) and less than 8.7% for PT (4.5-17.8 micrograms/ml). Linearity and recoveries were good over a broad range of drug levels for both assays. Excellent correlation was found with existing PB, ICS vs. EMIT on the IL Multistat III MCA (y = 1.26 + 1.00x; r = 0.994), ICS vs. Dupont aca (y = 0.832 + 1.01x; r = 0.997), and ICS vs. GLC (y = 0.08 + 0.99x; r = 0.998) methods, and PT, ICS vs. MCA (y = -1.76 + 1.04x; r = 0.985), ICS vs. aca (y = -2.02 + 1.054x; r = 0.987), and ICS vs. GLC (y = -0.26 + 0.990x; r = 0.999) methods. These assays were found to provide accurate drug analyses, good stat or batching capability, and good correlation with existing methods.

Performance of a new rate-nephelometric assay for rheumatoid factor, and its correlation with tube-titer results for human sera and synovial fluid.

We evaluated a rate-nephelometric assay for rheumatoid factor (RF), as developed for use with the Beckman Immunochemistry System (ICS). Within- run precision (CV) for low-, mid-, and high-dilution samples (60-400 kilo-int. units/L) was 3.5, 1.5, and 1.6%; between-run precision was 3.4%. Analytical linearity was excellent. Biological interference resulted in some degree of nonlinearity in more than 70% of the patients' samples tested. Sensitivities were 96.5 and 94.1% and specificities were 98.5 and 95.3% for the ICS RF and Wampole slide methods, respectively, for a clinically defined population of 170 patients. Results for 100 ICS RF-positive samples correlated well with concomitantly measured Calbiochem-Behring tube-titers. Weekly measurement of Calbiochem-Behring. Hyland Diagnostics, and ICL Scientific tube-titer values for RF along with the ICS RF values on samples from the same patients indicated stable ICS RF values but showed at least +/- 1 tube dilution variances both within and between the tube-titer methods. Therefore, it may not be appropriate to compare a precise new method with a relatively imprecise comparison method. Treatment of RF-positive samples with dithiothreitol, which disrupts the pentameric character of immunoglobulin M, rendered the samples negative by repeat ICS RF assay and confirmed the method's specificity for pentameric immunoglobulin M-RF. Serum RF concentration as determined by ICS paralleled changes in clinical symptoms in a patient treated with both effective and relatively ineffective regimens, which suggests a useful role for the assay in monitoring efficacy of clinical treatment.

Change in plasma cAMP and catecholamines in men subjected to the same relative amount of physical work stress.

This study has shown, for the first time, that the change in plasma adenosine 3',5' cyclic monophosphate (cAMP), from accommodation or trough levels, correlates highly in both progressive and continuous work stress experiments with epinephrine (E) at 0.990 and 0.898, and norepinephrine (NE) at 0.954 and 0.927, respectively, in men subjected to the same relative, rather than absolute, stress levels. All three analytes increased significantly (p less than 0.05) by the time each subject had reached 80% of their Vo2 max in the progressive experiments and after working at 80% of their Vo2 max continuously for 10 min. In no case did plasma cAMP rise before the catecholamines. The possible significance of these observations to net perceived relative physiological stress are discussed.

Simultaneous measurement of lecithin, sphingomyelin, phosphatidylglycerol, phosphatidylinositol, phosphatidylethanolamine, and phosphatidylserine in amniotic fluid.

A one-dimensional thin-layer chromatographic method is described by which the ratios and proportions of lecithin, sphingomyelin, phosphatidylglycerol, phosphatidylinositol, phosphatidylethanolamine, and phosphatidylserine in amniotic fluid may be simultaneously determined. Commercial chromatographic plates, 10 X 7.5 cm, pretreated with cupric chloride, are used. The solvent system is chloroform/methanol/ammonium hydroxide (30/17/1.5 by vol). The plates are sprayed with a cupric acetate (350 g/L)/phosphoric acid (80 mL/L) reagent and charred on a hot plate to make the phospholipids visible. The percentage of each phospholipid present is determined by direct reflectance or transmission densitometry. The correlation coefficients for the lecithin/sphingomyelin, phosphatidylinositol/sphingomyelin, and phosphatidylglycerol/sphingomyelin ratios of the two scanning methods are 0.971, 0.980, and 0.955, respectively, for between-day analyses.