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K Emancipator

Publications and source records attributed to K Emancipator.

16 recordsLinked to original sources
PubMed1997

Critical values: ASCP practice parameter. American Society of Clinical Pathologists.

Appropriate use of critical values improves patient outcome by ensuring that physicians are promptly notified of immediate life-threatening conditions. Conversely, overuse squanders resources and actually may impair patient outcome. A generic critical values list derived from interlaboratory surveys is an excellent starting point, but every laboratory must customize its list to meet the needs of the organization that it serves. Category-specific and once-per-period critical values can limit superfluous reporting, but they make the critical values list more complicated. Strict semantic interpretation of critical limits is appropriate. The best ways to report critical values are by telephone and by alphanumeric pager. When required, repeat analysis should precede critical value reporting. Laboratories should avoid reporting invalid results (due to poor specimen integrity, for example) as critical values. An institutional committee initially should approve, and periodically should review and revise, the critical values policy.

Clinical Laboratory Information Systems↗
PubMed1993

A theoretical evaluation of linearity.

The measure of linearity is an important part of the evaluation of a method. According to the NCCLS guidelines (Document EP6-P), results of a linearity experiment are fit to a straight line and judged linear either by visual evaluation, which is subjective, or by the lack-of-fit test. This approach depends on the precision of the method, is not necessarily conclusive, and fails to be quantitative. We define linearity as a measure of how well a first-order (linear) polynomial fits the data compared with a higher-order (nonlinear) polynomial. The major property of a linear polynomial is that the first derivative is a constant. The nonlinearity of a method can be measured by the difference between these two polynomials (first-order and higher-order) at specific values or, as an average, the root-mean difference. This approach is independent of the precision of the assay and is conclusive, quantitative, and objective.

Chemistry, Clinical↗
PubMed1993

A quantitative measure of nonlinearity.

Quantitative measures of the nonlinearity of an analytical method are defined as follows: the "(dimensional) nonlinearity" of a method is the square root of the mean of the square of the deviation of the response curve from a straight line, where the straight line is chosen to minimize the nonlinearity. The "relative nonlinearity" is defined as the dimensional nonlinearity divided by the difference between the maximum and minimum assayed values. These definitions may be used to develop practical criteria for linearity that are still objective. Calculation of the nonlinearity requires a method of curve-fitting. In this article, we use polynomial regression to demonstrate calculations, but the definition of nonlinearity also accommodates alternative nonlinear regression procedures.

Algorithms↗
PubMed1992

Comparison of two automated nephelometers.

The intercalibration precision and linearity were determined for two representative analytes, apolipoprotein A1 (apo A1) and immunoglobulin G (IgG), on the Beckman Array and the Behring Nephelometer 100 (BN-100). For two of nine samples analyzed, poor precision was observed for IgG with the Array. The poor precision for these two samples is attributed to large systematic shifts. A statistical non-linearity was observed for apo A1 with the BN-100, but this non-linearity does not exclude use of this assay for clinical diagnosis. Method comparisons were done for 12 analytes: apo A1, apo B, IgG, IgA, IgM, IgE, C3, C4, albumin, C-reactive protein, alpha-1-antitrypsin, and ceruloplasmin. These comparisons showed proportional biases of > 10% for seven of 12 analytes. Furthermore, correlation coefficients were < 0.96 for seven of 12 analytes. We conclude that comparing results obtained from the two different nephelometers is of only limited value for the individual patient.

Apolipoprotein A-I↗
PubMed1992

Immunohistologic demonstration of myocardial proteins with applications.

The authors used antibodies specific for creatine kinase MB isoenzyme (CK-MB) and myosin light chain-1 (MLC-1) for immunohistologic staining. At appropriate dilutions of antibody, frozen sections of human heart muscle were positive for both CK-MB and MLC-1, whereas sections of human skeletal muscle were negative for both proteins. Staining for both CK-MB and MLC-1 also was demonstrated in an immature teratoma. Furthermore, staining was localized to the rhabdomyosarcomatous elements within the teratoma; other components of the tumor did not stain for CK-MB or MLC-1. Biopsies of skeletal muscle revealed that regenerative, but not intact normal or degenerating, fibers also contained CK-MB and MLC-1. Immunohistologic stains for CK-MB and MLC-1 may be useful as tumor markers and as markers for regenerative muscle fibers.

Biopsy↗
PubMed1992

In vitro inactivation of bacterial endotoxin by human lipoproteins and apolipoproteins.

A chromogenic Limulus amebocyte lysate assay was used to measure the recovery of 1 endotoxin unit of endotoxin per ml. Purified human high-density lipoprotein, low-density lipoprotein, and apolipoprotein A1 (apo A1) at a maximum concentration of 1 g of protein per liter reduced the recovery to less than 40% of baseline in a both dose- and time-dependent manner and in the absence of other serum components. Furthermore, the lapine fever response to a dose of 1 ml of 5-ng/ml endotoxin per kg was reduced by greater than 0.5 degrees C (P less than 0.005) when the solution was preincubated in vitro with 0.5 g of apo A1 per liter. By the Limulus test, a maximum concentration of 0.01 g of apolipoprotein B (apo B) per liter (which contained deoxycholate, a known endotoxin-disaggregating agent) reduced recovery to 0% in a dose- but not time-dependent manner. In heat-inactivated (56 degrees C, 1 h) normal human serum, high-density lipoprotein cholesterol (P less than 0.005) and apo A1 (P less than 0.05) correlated inversely with endotoxin recovery, but, paradoxically, apo B correlated directly with endotoxin recovery (P less than 0.05), while low-density lipoprotein cholesterol showed no significant correlation. INTRALIPID alone had no effect on endotoxin recovery. Addition of a maximum of 10 g of INTRALIPID per liter to 0.0042 g of apo B per liter increased endotoxin recovery from approximately 30 to 80% (P less than 0.001), but addition of INTRALIPID to 0.25 g of apo A1 per liter decreased recovery from approximately 30 to 20% (P less than 0.001). We conclude that (i) lipoproteins are endotoxin inactivators; (ii) this ability of lipoproteins may be modulated by their lipid component (lipid-endotoxin interaction); (iii) apo A1 is capable of directly inactivating endotoxin (protein-endotoxin interaction).

Animals↗
PubMed1992

Low bias in assayed values of lipoprotein antigens--lipoprotein(a) and apolipoproteins A-I and B--in midday postprandial blood specimens compared with morning fasting specimens.

Two-hour postprandial specimens have a -14% proportional bias for lipoprotein(a) [Lp(a)], a -0.035 g/L systematic bias for apolipoprotein (apo) A-I, and a -9% proportional bias for apo B, compared with values in 12-h fasting specimens. Although a physiological hemodilution appears to account for a portion of these biases, other major factors must be implicated for Lp(a) and apo B. Even after dilutional effects are controlled for, assayed values of Lp(a) are 11-13% lower, and assayed values of apo B are 8-9% lower, in postprandial specimens than in fasting specimens. Therefore, the time of collection of a blood sample relative to the last meal can significantly affect assayed values of lipoprotein antigens. Further studies are needed to determine whether these observations result from a physiological sequestering of lipoproteins in the postprandial state or from negative interferences affecting the assays of lipoprotein antigens.

Apolipoprotein A-I↗
PubMed1990

Diagnosis of ectopic pregnancy by the rate of increase of choriogonadotropin in serum: diagnostic criteria compared.

We compare three methods for using the rate of change of human choriogonadotropin (hCG) concentration in serum to diagnose ectopic pregnancy. With Method I, the lower limit for the rate of increase of serum hCG in normal pregnancy is 66% per 48 h. With Method II, a different lower limit of normal is specified for each of four discrete sampling intervals of hCG. With Method III, the lower limit of normal is determined by a continuous discriminant function of the initial hCG concentration. If the initial hCG concentration is less than or equal to 2000 int. units/L (Second International Standard), all three methods have acceptable diagnostic efficiencies, and there are no statistically significant differences among conclusions from the methods. None of the three methods performs satisfactorily if the initial hCG concentration is greater than 2000 int. units/L. We recommend Method I because it is simpler than the other two.

Chorionic Gonadotropin↗
PubMed1990

Bromide interference: is less really better?

Increased serum bromide may result from the ingestion of various drugs and from environmental exposures. Chloride methods that are less susceptible to bromide interference have a clinical disadvantage in that they are less likely to arouse suspicion in cases of bromide toxicity. When there is a clinical suspicion of bromide toxicity, differences among various analyzers in the amount of interference caused by bromide may be exploited to confirm this suspicion and to estimate the concentration of bromide in serum.

Bromides↗
PubMed1989

Sensitivity, specificity, and reproducibility of four measures of laboratory turnaround time.

The authors studied the performance of four measures of laboratory turnaround time: the mean, median, 90th percentile, and proportion of tests reported within a predetermined cut-off interval (proportion of acceptable tests [PAT]). Measures were examined with the use of turnaround time data from 11,070 stat partial thromboplastin times, 16,761 urine cultures, and 28,055 stat electrolyte panels performed by a single laboratory. For laboratories with long turnaround times, the most important quality of a turnaround time measure is high reproducibility, so that improvement in reporting speed can be distinguished from random variation resulting from sampling. The mean was found to be the most reproducible of the four measures, followed by the median. The mean achieved acceptable precision with sample sizes of 100-500 tests. For laboratories with normally rapid turnaround times, the most important quality of a measure is high sensitivity and specificity for detecting whether turnaround time has dropped below standards. The PAT was found to be the best measure of turnaround time in this setting but required sample sizes of at least 500 tests to achieve acceptable accuracy. Laboratory turnaround time may be measured for different reasons. The method of measurement should be chosen with an eye toward its intended application.

Electrolytes↗
PubMed1988

Analytical versus clinical sensitivity and specificity in pregnancy testing.

A typical urine pregnancy test with the enzyme-linked immunoassay for human chorionic gonadotropin (Tandem Icon human chorionic gonadotropin) was performed as was a qualitative serum radioimmunoassay for human chorionic gonadotropin when the positive cutoff for the latter was set at 30 IU/L. There was 99.5% concordance between the two methods when performed on 871 simultaneous urine and serum specimens. Although the serum radioimmunoassay can detect levels of human chorionic gonadotropin as low as 10 IU/L, in this study the majority of patients with serum levels between 10 and 30 IU/L were not pregnant on clinical follow-up. Of nine patients with adequate clinical follow-up, a negative urine pregnancy test result, and a serum human chorionic gonadotropin level between 10 and 30 IU/L, only one proved to be pregnant. The Tandem Icon human chorionic gonadotropin urine test is sufficient for routine pregnancy testing and to rule out the need for immediate intervention in cases of ectopic pregnancy.

Chorionic Gonadotropin↗
PubMed1988

Secretion of creatine kinase MB isoenzyme by an immature teratoma with predominant rhabdomyosarcomatous elements.

A 37-year-old man with metastatic immature (malignant) teratoma with prominent rhabdomyosarcomatous elements had markedly increased activity of creatine kinase (EC 2.7.3.2) MB in serum. There was no electrocardiographic evidence of infarction or ischemia, and autopsy revealed no myocardial infarction, significant coronary atherosclerosis, myocarditis, or invasion of the heart by tumor. A high proportion of the creatine kinase activity in a homogenate of the tumor was attributable to the MB isoenzyme. Persistent increases of creatine kinase-MB and an unusually high MB isoenzyme activity, out of proportion to total creatine kinase activity, may indicate a nonmyocardial origin of this isoenzyme.

Adult↗
PubMed1985

Hidden and classical 19S IgM rheumatoid factor in a juvenile rheumatoid arthritis patient.

Hidden 19S IgM rheumatoid factors (RF), i.e., 19S IgM RF which can be detected in the IgM containing fraction after acid gel filtration of serum, are found in 59-68% of patients with juvenile rheumatoid arthritis (JRA). Their presence generally correlates with disease activity. We describe a 12 year-old female with a polyarticular onset of JRA who, during her first 15 months of disease, was seronegative but had hidden RF titers of 1:128----1:256. Inhibition studies on her hidden RF showed specificity for HIgG greater than RIgG and equal specificity for the human IgG subclasses (IgG1 = IgG3). In the second and third year of disease, she became seropositive with RF titers varying from 1:40 to 1:320 while her hemolytic titers on her IgM fractions were decreased from 1:128 to 1:32. Inhibition studies now demonstrated a higher avidity for RIgG; and HIgG3 inhibited more than HIgG1. These studies documented for the first time a JRA patient who early in the disease was negative for RF and positive for hidden RF, and who later became seropositive.

Arthritis, Juvenile↗