Immunoreactivity of standards and reference preparations used in the radioimmunoassay of follicle-stimulating and luteinizing hormones in serum.
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Follicle Stimulating Hormone↗
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The serology of Pseudomonas aeruginosa analysed by means of quantitative immunoelectrophoretic methods. V. Thermostability, resistance to degradation by plasmin activity and storage conditions of a polyvalent P. aeruginosa reference standard-antigen.
The stability of a polyvalent Pseudomonas aeruginosa antigen (St-Ag) was analysed under different experimental conditions by quantitative immunoelectrophoretic methods. St-Ag did not undergo proteolytic degradation by plasmin which is present in the corresponding polyvalent rabbit antiserum (St-Ab) against St-Ag. Storage at -30 degrees C for up to 4 years caused no qualitative changes in St-Ag and, after 1 year, only minor quantitative changes could be revealed. Repeated thawing and freezing caused no changes in St-Ag whereas storage at 4 degrees C, or at room temperature, caused gradual degradation of most of the antigens of St-Ag, beginning after 1 week. Heating up to 40 degrees C for 2 min did not change St-Ag, but heating for longer periods of time or at higher temperatures gradually destroyed most of the antigens of St-Ag. The most thermostable antigen in St-Ag was number 37 which is related to the group specific O antigens.
Antigens, Bacterial↗
The serology of Pseudomonas aeruginosa analysed by means of quantitative immunoelectrophoretic methods. III. Reproducibility of a polyvalent P. aeruginosa reference standard-antigen.
The reproducibility of a polyvalent Pseudomonas aeruginosa antigen (St-Ag) composed of a mixture of antigens from 4 O groups of this bacterium has been studied. Ten batches of St-Ag were produced, and each of these and each of the 10 batches of antigens from the 4 strains of P. aeruginosa were compared with St-Ag batch 1 by means of quantitative immunoelectrophoretic methods and a polyvalent antiserum (St-Ab) raised against St-Ag. Fifty-three of the 55 antigens of St-Ag were stable and could be reproduced with reasonable precision in all 10 batches, and 3 of the 4 strains of P. aeruginosa were stable in antigen composition in all batches. One of the strains (0-5A) had lost 2 antigens in the last 5 batches, and the concentrations of 7 other antigens were simultaneously changed, reflecting a smooth-rough dissociation. The disappearance of the 2 antigens in the latest 5 batches of 0-5A was also reflected in similar changes in the antigen composition of the latest 5 batches of St-Ag.
Antigens, Bacterial↗
Lactate-to-pyruvate or pyruvate-to-lactate assay for lactate dehydrogenase: a re-examination.
The pyruvate-to-lactate assay for determining lactate dehydrogenase (EC 1.1.1.27) can now yield linearity equal to or better than that obtained by the lactate-to-pyruvate assay. In addition, there are significant advantages to the pyruvate-to-lactate reaction: (a) a greater change in absorbance per unit time, which allows more accurate spectrophotometric readout; (b) lower reactant concentrations are required, which substantially reduces the cost per assay; (c) solid reagents are used to prepare the assay solution; and (d) reagent solutions are more stable. However, impurities present in commercial NADH preparations may substantially affect measured lactated dehydrogenase activities; therefore, a Standard Reference Material for NADH is being developed for issuance by the National Bureau of Standards.
L-Lactate Dehydrogenase↗
Ossification of femoral head in infancy. I. Normal standards.
Observations made in 455 Malmö infants with assumedly normal ossification of the femoral heads were used for establishing reference standards for the age at onset of the ossification and for the size of the ossification centers according to sex and age.
Age Factors↗
Energy-dispersive x-ray fluorescence spectroscopy and inductively coupled plasma emission spectrometry evaluated for multielement analysis in complex biological matrices.
Energy-dispersive x-ray spectroscopy and inductively coupled plasma emission spectrometry were evaluated as methods for routine multielement analysis of biological material. Standard samples included Standard Reference Materials (National Bureau of Standards), compounded mixtures, and supplements that provided a wide range of elemental concentrations for analysis. Elements included in this study were Zn, Pb, Ni, Mn, Fe, Mg, Cu, Ca, As, Se, Br, Rb, and Sr. Standards were analyzed as unknowns by participating laboratories. The two methods were evaluated for sensitivity, precision, and accuracy, and the results compared to those obtained for atomic absorption spectrometric analysis of identical standard unknowns. Both methods compared favorably and both were determined to be highly reliable for such an application. Advantages and disadvantages of each method are compared and discussed.
Animals↗
Radioimmunoassay for the simultaneous detection and quantitation of hepatitis B surface antigen and of the homologous antibody.
A solid-phase radioimmunoassay procedure is presented, which allows the simultaneous detection and quantitation of HB, Ag and of anti-HBs. This procedure involves short preliminary incubation of test sera and of negative controls with a standard HB, Ag. The standard HBs Ag is diluted, according to preliminary assays, in order to yield a count ratio to negative controls of 10 to 1. Therefore, a value of 10 is ascribed to the counts of positive controls (standard HBs, Ag + HBs-negative serum) and counts of all test sera are proportionally related. The values obtained are denominated HBs Units. Test sera are considered to be positive for HBs Ag or anti-HBs when the corresponding HBs Units are significantly higher or lower, respectively, than the average value of standard antigen controls. Including the reference standard HBs Ag controls in each set of assays ensures the quantitative reproducibility of results among different assays and among different laboratories. Titres of serum HBs Ag and anti-HBs can be expressed as end-point dilutions, simply by plotting the corresponding HBs Units on a nomography. This was drawn according to the indications emerging from analysis of the radioimmunoassay kinetics. Laboratory assays and the practical application of the combined procedure over several thousands determinations showed that the binding capacity of the solid-phase substrate used (small antibody-coated polystyrene tubes) is extremely homogeneous. Such homogeneity accounts for a very high accuracy and reproducibility of quantitative results.
Antibodies↗
A simple and rapid technic for radioimmunoassay and calculation of plasma steroid concentrations.
A simple RIA technic for plasma steroids is described: Extraction residues or reference standards are dissolved in 20 microliter ethyl alcohol, or 20 microliter of alcoholic plasma extracts are given directly into RIA tubes; 500 microliter tracer solution, containing a known tracer mass, and, after mixing, 500 microliter antiserum solution or buffer solution are added, followed by 20 min incubation at room temperature and 20 min standing in an ice bath. Free from bound activity is separated by charcoal coated florisil or silicagel. Plasma steroid levels are calculated by a simple equation. An immunologic equivalent to the tracer mass present in the reaction mixture serves as reference value. Drawing of standard curves is not necessary for every assay. The linear transformation used here allows the number of reference standards to be reduced. So also single samples can be analyzed with relatively low effort.
Estradiol↗
Human pituitary gonadotropin index. I. Standardized LRH test criteria for evaluation of functional amenorrhea.
LRH test were carried out by giving 339 amenorrheic women and 74 normally menstruating volunteers an intravenous injection of 25 mug LRH (Hoe 471). Plasma LH and FSH were measured by RIA in two laboratories (Tuebingen and Ulm) using two standard reference preparations: LER 907 and 2nd IRP-HMG. The average conversion factors between the two standard preparations were calculated at 5.0 for LH and 25.0 for FSH. Furthermore, the estradiol-17beta levels were measured in 139 out of the 339 patients immediately before and 60 minutes after LRH injection. Taking the episodic and cyclic plasma gonadotropin fluctuations into consideration a shorthand system classifying the gonadotropin baseline (BI-BIV) and LH responses to 25 mug LRH (R0-R2) has been established and is referred to as Human Pituitary Gonadotropin Index (HPGI). It is possible to achieve reproducible gonadotropin results in two different laboratories using two different standard reference preparations. Two separate, randomly selected groups of amenorrheic women were found to have the same percent distribution of the HPGI. A correlation coefficient of r equal 0.67 between basal and LRH stimulated plasma LH levels does not sufficiently characterize the individual LH response behavior. A significant increase of plasma LH and FSH within the test period (60') reveals that the iv administration of 25 mug LRH represents an adequate dose for the LRH test in women. The HPGI which characterizes the functional state of gonadostat, may become a useful diagnostic index for evaluating women with anovulatory disease before, during, and after therapy.
Adolescent↗
An improved gas-liquid chromatographic procedure for the determination of amitriptyline and nortriptyline levels in plasma using nitrogen-sensitive detectors.
An improved gas-liquid chromatographic procedure for the plasma level determination of amitriptyline and nortriptyline using nitrogen-sensitive detectors is described. Derivatization of the secondary amines using trifluoroacetic anhydride greatly improves the response and reproducibility of the assay. Plasma samples containing as little as 5 ng/ml of amitriptyline and nortriptyline can be assayed precisely and reproducibly, using protriptyline as internal reference standard.
Amitriptyline↗
Standardization of serum protein analyses.
A brief historical review is presented of the development of bovine serum albumin as a standard for the determination of serum total protein. Bovine serum albumin is now available as a standard reference material from the National Bureau of Standards. Also reviewed is the present status of the immunoglobulin standards.
Biuret Reaction↗
Reference preparation to standardize results of serological tests for rheumatoid factor.
The variance of between-laboratory results for rheumatoid factor tests was reduced through the use of a reference serum preparation. Two separate proficiency testing surveys have shown reduction of 58 to 81% in variance with samples of differing levels and composition. Reduction of variance was seen in data from laboratories in which the same methods and reagents were used, but greater reduction in variance was seen in results from laboratories using different methods and reagents. This study demonstrates that comparability of results of rheumatoid factor tests can be significantly improved through the use of a standard reference serum preparation and that confidence in such results can therefore be increased. A serum rheumatoid factor level of approximately 50 IU/ml is equivalent to a titer of 160 in the Singer-Plotz latex test, which has traditionally been accepted as evidence of rheumatoid arthritis.
Arthritis, Rheumatoid↗
Application of linear programming to dose optimization in intracavitary implant therapy.
Linear programming can be used to optimize intracavitary brachytherapy for carcinoma of the cervix. A method has been developed which gives meaningful output and is described. A set of reference points were necessary in addition to the standard reference points. Point A as well as an array of points for adjacent radiation sensitive normal structures were used in order to obtain isodose curves conforming to those commonly used for therapy. In addition, arbitrary upper and lower limits of dose at selected points were needed and were set to conform to systems commonly used clinically for intracavitary therapy. It was immediately evident that a wide variety of loadings can be used that deliver appropriate or improved doses to reference points while minimizing normal tissue dose. The loadings represent arrangements which are not commonly used in many clinics but offer potential for clinical use.
Brachytherapy↗
Serum standards for the bioassay of aminoglycosides in cerebrospinal fluid.
Four diluents were compared as reference standards for the assay of gentamicin in cerebrospinal fluid (CSF): human CSF, human serum, distilled water, and 150 mmol NaCl/4.5 mmol CaCl2. Standards prepared in pooled human serum were the best alternative to CSF for the assay of gentamicin and were also useful for the assay of tobramycin, netilmicin, amikacin, and sisomicin. The pH (6.0-9.8) of CSF did not alter the results of the assay.
Aminoglycosides↗
A comparison of serum electrolyte results by Technicon's Flame III and Flame IV AutoAnalyser system.
A comparison of Technicon's (Technicon, Tarrytown, N. Y., 10591) Flame III and Flame IV electrolyte Auto-Analyzer systems for the determination of Na+, K+, Cl- and CO2 in serum is described. Results from the Flame IV are determined over three periods of time and compared to those of the referee Flame III system. The Optional Digital Printer and Linearizer Modules are not used with the described system. The Flame IV AutoAnalyzer is calibrated with a multi-point calibration technique (aqueous reference standards) rather than the single-point calibration technique (albumin reference material) used by the AutoAnalyzer II. Results for the Flame IV are shown to be comparable with those for the Flame III.
Autoanalysis↗
Biologically active luteinizing hormone (LH) in plasma: II. Comparison with immunologically active LH levels throughout the human menstrual cycle.
The levels of biologically active luteinizing hormone were determined by an in vitro bioassay method in plasma samples collected daily over a complete menstrual cycle from 12 menstruating women. These cycles were normal according to a number of criteria, including daily plasma levels of oestradiol, 17-hydroxyprogesterone and progesterone. Immunoreactive LH was estimated in the same 12 cycles by a radio-immunoassay (RIA) procedure (HCG-RIA) using an HCG antiserum and iodinated HCG. The 2nd IRP of HMG was selected as standard although significant deviations from parallelism were found with 7 out of the 12 plasma pools studied. The use of the 1st IRP of human pituitary gonadotrophins (FSH and LH (ICSH)) for bioassay (herafter HPG-1st IRP) as standard in this system resulted invariably in invalid assays, due to lack of parallelism. Immunoreactive LH was also measured in 8 of the 12 cycles by a RIA procedure (HLA-RIA) using a human LH antiserum and iodinated human LH of pituitary origin. Results are expressed in terms of the HPG-1st IRP. The plasma levels of biologically and immunologically active LH were qualitatively similar throughout the menstrual cycle. However, the LH levels measured by the bioassay invariably exceeded those estimated by the RIA procedures. The biological to immunological (B/I) ratio over the entire menstrual cycle (312 comparisons) was 5.5 with 95% confidence limits at 5.2 and 5.8 when the HCG-RIA system was employed. Using the HLH-RIA system (208 comparisons), the corresponding ratio was 6.4 (6.0:6.9). When regression lines were calculated using the bioassay results as the independent variable and the RIA results as the dependent variable, the 95% confidence limits of the regression lines did not include the origin. Furthermore,, in keeping with the high B/I ratios, the slopes of the two regression lines and their conficence limits differed markedly from unity. It is concluded that although qualitatively similar profiles were observed between the biological and immunological activities throughtout the menstrual cycle, two aspects require further attention. Firstly, the elevated B/I ratios together with the behaviour of the dose-effect lines obtained with different standards in the various RIA systems suggest that presently available reference standard preparations of pituitary and/or urinary origin are not suitable for the assay of LH in human plasms. Secondly, from the regression analyses of the biological and immunological activities it is infered that the RIA methods detect immunological activity which is not associated with biological activity. If so, the validity of these RIA procedures for specifically measuring low levels of biologically active LH in plasma may be in question.
Adult↗
International Committee for Standardization in Haematology. Recommendations for reference method for haemoglobinometry in human blood (ICSH standard EP 6/2: 1977) and specifications for international haemiglobincyanide reference preparation (ICSH standard EP 6/3: 1977).
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Cyanides↗
Which radiographic plane should be used to quantify the distal tibia angle on weightbearing CT images?
BACKGROUND: Precise quantification of distal tibial alignment is essential for planning corrective osteotomies and ankle joint replacement surgery. The lateral distal tibial angle (LDTA) is the principal radiographic parameter used for this purpose. While LDTA is increasingly measured on weightbearing cone-beam CT (WBCT) using two-dimensional coronal slices, the optimal measurement plane remains unclear. METHODS: In this retrospective comparative study, full-leg WBCT scans of patients scheduled for supramalleolar osteotomy (n = 20; mean age 47 ± 12.8 years) were analyzed. LDTA was measured on three coronal planes of the distal tibial plafond (anterior edge, mid-dome, posterior edge) and compared with semi-automated three-dimensional (3D) tibial alignment measurements as the reference standard. RESULTS: Mid-dome LDTA showed no significant difference from the 3D reference (p > 0.05) and demonstrated excellent agreement. Anterior measurements significantly overestimated LDTA, while posterior measurements underestimated it (both p < 0.05), with only fair agreement. CONCLUSION: LDTA should be measured at the mid-dome of the distal tibial plafond on WBCT to ensure accurate and reproducible alignment assessment. LEVEL OF EVIDENCE: Level III - Retrospective Comparative Study.
Humans↗