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Determination of trace elements in standard reference materials by the ko-standardization method.

The ko-standardization method is suitable for routine multielement determinations by reactor neutron activation analysis (NAA). Investigation of NIST standard reference materials SRM 1571 Orchard Leaves, SRM 1572 Citrus Leaves, and SRM 1573 Tomato Leaves showed the systematic error of 12 certified elements determined to be less than 8%. Thirty-four elements were determined in NIST proposed SRM 1515 Apple Leaves.

Neutron Activation Analysis↗

Selection of patients for biological standardization as exemplified by standardization of mugwort, goosefoot and English plantain pollen allergen extracts/preparations.

The biological activity of a partly purified, biochemically/immunochemically characterized mugwort pollen allergen preparation and crude pollen extracts of mugwort, goosefoot and English plantain was determined by means of skin prick test (SPT). The patient inclusion criteria with mugwort were a well-defined positive clinical history and a positive SPT. Symptoms related to goosefoot/English plantain pollens are difficult to define, as these weeds flower during the grass pollen season. Thus patients tested with these allergens did not fulfill the most important inclusion criterion for so-called biological standardization. To elicit a wheal of the same size as that produced by histamine 1 mg/ml required 100 to 10,000 times more material from these weeds, than from mugwort and other pollen allergen extracts investigated earlier. One thousand Biological Units/ml (BU/ml) corresponded to 8.3 micrograms dry weight (dw/ml) of the crude and 1.8 micrograms dw/ml of the purified mugwort pollen allergen preparation. Only 7/22 goosefoot-and English plantain-tested patients were positive at conjunctival or nasal challenge. All three weeds showed a similar composition with 5-10 allergens by CIE/CRIE analysis and 10-13 by immunoblotting analysis. One dominating allergen (approx. 15,000 d), could be identified for each weed species by protein gel blot after separation by SDS g-PAGE. There was no other explanation for the difference in biological activity than the criteria of selection. If there is no obvious clinical history, which is the main patient inclusion criterion in biological standardization, then additional criteria should be used.

Adolescent↗

Standardization of broth microdilution and disk diffusion susceptibility tests for Actinobacillus pleuropneumoniae and Haemophilus somnus: quality control standards for ceftiofur, enrofloxacin, florfenicol, gentamicin, penicillin, tetracycline, tilmicosin, and trimethoprim-sulfamethoxazole.

Quality control (QC) standards for the in vitro antimicrobial susceptibility testing of two fastidious veterinary pathogens, Actinobacillus pleuropneumoniae and Haemophilus somnus, were developed in a multilaboratory study according to procedures established by the National Committee for Clinical Laboratory Standards for broth microdilution and disk diffusion testing. The medium recommended for the broth microdilution testing is cation-adjusted Mueller-Hinton broth supplemented with 2% lysed horse blood, 2% yeast extract, and 2% supplement C. This medium has been designated veterinary fastidious medium. The medium recommended for the disk diffusion testing is chocolate Mueller-Hinton agar. The recommended QC organisms are A. pleuropneumoniae ATCC 27090 and H. somnus ATCC 700025. The QC MICs of ceftiofur, enrofloxacin, florfenicol, gentamicin, penicillin, tetracycline, tilmicosin, and trimethoprim-sulfamethoxazole were determined for each isolate, as were the zone size ranges. Of the results from the participating laboratories, 94.0% of the zone diameter results and 97.0% of the MIC results fell within the suggested QC ranges for all compounds. These QC guidelines should allow greater accuracy in interpreting results when testing these antimicrobial agents against fastidious pathogens.

Actinobacillus Infections↗

In vitro allergy testing needs better standardization--test results from different laboratories lack comparability mostly due to missing effective standards.

Correct determination of specific IgE is important for the diagnosis of allergic diseases. Different detection systems are supposed to yield similar results of this standardized parameter. In order to investigate this assumption, 40 sera from allergic patients were sent in eight mailings to 23 laboratories over a 2-year period. Three IgE determinations in each serum had to be performed according to laboratory-specific methods. Whereas 'wrong' results were rare with any of the methods and the overall results to a large degree comparable, sensitivity and specificity seemed to vary considerably between antigens, methods, companies and laboratories. According to our observations, better standardization of test reagents and test methods by the suppliers is essential in order to harmonize the test results and to avoid wrong conclusions. At present, the diversity of techniques that are used for IgE determination leads to quite divergent results, and the allergist has to know that. And finally, the legislator is urged to better control these diagnostic tools, because wrong results may lead to life-threatening situations.

Evaluation Studies as Topic↗

Medical computing standards ASTM (American Society for Testing and Materials) Committee E-31. A review of published standards and current projects February, 1992.

This document describes the activities of ASTM Committee E-31 in the area of standards for computer systems in medical applications. Some of these efforts have already culminated in published standards, some are well along in the development process, and some are just getting started.

Clinical Laboratory Information Systems↗

[Reporting studies of diagnostic accuracy according to a standard method; the Standards for Reporting of Diagnostic Accuracy (STARD)].

The objective of the 'Standards for Reporting of Diagnostic Accuracy' (STARD) initiative is to improve the reporting of studies of diagnostic accuracy, so as to allow readers to assess the potential for bias in a study and to evaluate the generalibility of its results. The group searched the literature to identify publications on the appropriate conduct and reporting of diagnostic studies. This was used to draw up a list of potential items. During a consensus meeting, a group of researchers, medical journal editors, and members of professional organisations reduced this list to a usable checklist. Wherever possible, evidence from the literature was used to justify the decisions made. The search for published guidelines about diagnostic research yielded 33 previously published checklists, from which a list of 75 potential items was extracted. At the consensus meeting, participants shortened the list to a 25-item checklist. A generic flow diagram was drawn up to provide guidance on the method for including patients, the order in which tests were to be conducted and the number of patients to undergo the test being evaluated, the reference standard, or both. A scientific publication can only be assessed when the reporting is both correct and complete. Use of the checklist and flow diagram will improve the quality of reports produced, to the advantage of clinicians, researchers, reviewers, journal editors and other interested parties.

Algorithms↗

[Problems in standardization of the immunochemical detection of plasma proteins. I. International reference standards for plasma proteins. II. Immunochemical relation of measurement signals and values].

When the results of plasmaprotein determination--dependent on the reagents, methods and other factors--are expressed in international units (IU) a better comparison of the results between different labs is possible. By this means and using the corresponding reference values and reference intervals the reliability of the interpretation of laboratory data will increase. The situation regarding the WHO IRP's for plasma proteins (approx. 20 parameters) and the relation from IU to mg in the reagents of the Behringwerke AG are reported. The overlability of WHO IRP's has not allowed yet to achieve an optimal standardization of the immunochemical methods for measurement of plasma proteins. This depends especially on the complexity of the antigen-antibody reaction. The relationship between the measured signal and the hence obtained value will be discussed in details in the second part of this paper. Hereby especially the reciprocal interdependence between physicochemical properties of proteins and the deriving immunochemical behaviour as well as the dependence of the results from the quality of the antibodies-containing reagents are also considered. Possible solutions for a better control system of the plasma protein determination by using the so called master calibrators as internal support for validation will be presented. Furthermore, general immunochemical postulates and rules for optimization of the standardization of plasma protein determination will be proposed and discussed.

Antigen-Antibody Complex↗

Preparation, characterization and storage of human ferritin for use as a standard for the assay of serum ferritin. International Committee for Standardization in Haematology (Expert Panel on Iron).

This paper describes studies on the source, preparation, characterization and storage of human ferritin for use as a standard for the immunoassay of serum ferritin. Ferritin was prepared from the liver or spleen by methods including either ultracentrifugation or cadmium sulphate crystallization. Preparations were characterized by polyacrylamide gel electrophoresis in dissociating and non-dissociating buffers, iso-electric focusing, analysis of amino acid composition and measurement of protein content. The protein content of solutions of liver or spleen ferritin may be determined by the method of Lowry with bovine serum albumin as standard. Lyophilization under carefully controlled conditions in buffer containing high concentrations of albumin provides a stable preparation of ferritin. Accelerated degradation and collaborative immunological studies of two lyophilized preparations of ferritin, one from liver and one from spleen, indicate that either is an acceptable reference material.

Ferritins↗

[Studies on "Fast Green FCF Standard" for the dye standard on the National Institute of Health Sciences].

The raw material for Fast Green FCF was tested for preparation of the "Fast Green FCF Standard (C.I. 42053)". Analytical data obtained were as follows: paper chromatography, only one spot is observed; arsenic content, 0.38 microgram/g; chloride content, 0.11%; sulfate content, 3.30%; heavy metals, lead, 8.0 micrograms/g, manganese, 28.1 micrograms/g, and chromium, 1.6 micrograms/g; infrared spectra, 1575 cm-1, 1169 cm-1, and 1033 cm-1; loss on drying, 2.39%; assay, 93.0% by the titanium trichloride titration. Based on the above results, the raw material was authorized as the Dye Standard of National Institute of Health Sciences.

Coloring Agents↗

Standards of nutritional care in pediatric oncology: results from a nationwide survey on the standards of practice in pediatric oncology. A Children's Oncology Group study.

BACKGROUND: The prevalence of malnutrition in children with cancer ranges between 8% and 60%. Malnutrition is strongly associated with the nature of treatment and increases an individual's risk of infection. Clinical studies have suggested that nutrition intervention may decrease toxicity and improve survival in the oncology population. In order to identify the standards of practice in the nutritional management of a child with cancer, we conducted an international survey in institutions that are part of the Children's Oncology Group (COG) consortium. PROCEDURE: Surveys were submitted to 233 participating COG institutions. We requested one member in three disciplines complete the survey: physician, registered dietitian, and nurse or nurse practitioner. The survey was returned to the nutrition sub-committee of COG. RESULTS: Fifty-four percent of institutions responded to the survey. We found no consistency in the provision of nutrition services. Assessment of nutritional status does not routinely occur and different indices are employed to indicate the nutrition status of a patient. Institutions rely upon different guidelines when categorizing malnutrition. When nutrition intervention is clinically indicated, a variety of approaches are employed. CONCLUSIONS: This survey did not find standardized nutrition protocols being employed in the pediatric oncology population. The effect of varied nutrition practices on the quality of life, toxicity, and outcome in children with cancer is unknown. Prior to the initiation of clinical trials, uniform guidelines need to be developed and validated. Future clinical trials need to investigate the most efficacious method of nutrition assessment and intervention and its effect on quality of life, toxicity, and survival in children with cancer.

Child↗

Quantitative analysis using gas chromatography/combustion/isotope ratio mass spectrometry and standard addition of intrinsically labelled standards (SAIL)--application to isoflavones in foods.

We have investigated a novel application of gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) for the quantitative analysis of the isoflavones in food matrices. Previous methods have been hampered by the lack of analytical standards to introduce early enough in the extraction procedure to allow compensations for losses at all stages of the procedure. In this work we have produced standard materials that can be added at the initial extraction, by intrinsically labelling soya plants by growing them in an atmosphere enriched in the stable isotope of carbon in CO(2). On analysis these plants were shown to contain phytoestrogens at a high (up to 20%) level of enrichment. The dried plant material has been used to estimate the isoflavone concentrations of a set of spiked flours. For daidzein the methodology was shown to produce results comparable to those achieved by GC/MS techniques. The method was less successful for genistein, possibly due to the greater fragility of this compound under the conditions required for the analysis.

Carbon Isotopes↗

Impact of standard procedures and clinical standards on cost-effectiveness and intensive care unit performance in adult patients after cardiac surgery.

OBJECTIVE: To investigate the impact of organizational procedures on intensive care unit (ICU) performance and cost-effectiveness after cardiac surgery. DESIGN: Prospective study. SETTING: Cardiothoracic ICU at a university hospital. PATIENTS: Thousand five hundred twenty-six consecutive patients over a period of 18 months. INTERVENTIONS: The first 6 months were used as the control period. Afterwards selected organizational changes were introduced, such as written standard procedures, time schedules and discharge reports. MEASUREMENTS: Demographic data, surgical procedures, length of ICU and hospital stay and hospital outcome were recorded. Severity of illness was assessed daily using Acute Physiology and Chronic Health Evaluation (APACHE II), Simplified Acute Physiology Score (SAPS II) and Organ Failure Score (OFS). Intensity of treatment and nursing care was monitored by the Therapeutic Intervention Scoring System (TISS). RIYADH ICU Program (RIP 5.0) was used to determine the relationship of observed to predicted mortality (standardized mortality ratio SMR) and the effective costs per survivor. MAIN RESULTS: SMR decreased continuously after the establishment of new management procedures while all other factors all other factors remained unchanged. Comparing outcome according to APACHE II on ICU admission demonstrated a significantly increased ICU performance in high risk patients with an APACHE II of 20-30 points (p < 0.05) while effective costs per survivor decreased significantly from DM 29,988 to DM 13,568 DM (p < 0.05). CONCLUSIONS: Organizational changes can improve ICU performance and cost-effectiveness after cardiac surgery. The RIP may be used to monitor the clinical and economical effects of change.

APACHE↗

Diagnostic value of Q waves outside standard precordial lead points in left anterior myocardial infarction undetectable by standard 12-lead electrocardiogram.

Body surface potential maps were recorded for 52 patients with solitary anterior myocardial infarction and 57 normal subjects. All patients had pure anterior wall asynergy on a left ventriculogram but no diagnostic Q wave on the standard 12-lead electrocardiogram. Q wave (greater than 30 msec) distributions on the body surface of the patients and normals were compared. The frequency of Q waves in the area above V1-V2 and in the right middle chest was significantly higher in patients than in normals. The sensitivity of Q waves for asynergy in leads from both these areas was 19-60%. The positive predictive value was 67-94%. The frequency of Q waves was significantly higher in severe asynergy than in mild asynergy. A combination of two selected unipolar leads from these areas yielded a sensitivity and specificity of 33% and 95%, respectively. With a combination of three leads, these values were 42% and 93% and with four leads 48% and 88%, respectively. The results indicate that several unipolar leads from the area above V1-V2 and from the right middle chest in addition to the standard 12-lead electrocardiogram may improve the electrocardiographic diagnostic accuracy of myocardial infarction.

Electrocardiography↗

Comparison of three methods of antifungal susceptibility testing with the proposed NCCLS standard broth macrodilution assay: lack of effect of phenol red. National Committee for Clinical Laboratory Standards.

Three microtiter plate adaptations of the NCCLS proposed standard for antifungal susceptibility testing were evaluated and compared to the NCCLS broth macrodilution method. Thirteen different fungi, including yeasts and moulds were studied. The first microtiter based method was performed exactly as described for the tube dilution assay, with the exception of performance of the assay in 100 microliter in wells of the microtiter plate. The second assay was the same as the first, except for the deletion of phenol red from the RPMI 1640. The third microtiter assay was based on the reduction of the formazan dye, XTT, after only 24 hours of incubation. All three microtiter methods compared favorably with the macrodilution method, when visually read after either 24 or 48 hours of incubation. Minimum inhibitory concentrations obtained by the XTT assay were usually lower than those obtained by the methods requiring a visual end point determination. Results were reproducible and comparable to those obtained with the NCCLS method. We conclude that microtiter plate adaptation of the NCCLS proposed standard is feasible and the presence of phenol red does not alter the results with the drugs tested. A 24 hour assay using XTT may provide a quicker and more quantitative method of susceptibility testing of fungi. Further investigation of this approach is warranted.

Fungi↗

New technology, old standards: disparate activated clotting time measurements by the Hemochron Jr compared with the standard Hemochron.

BACKGROUND: Accurate control of the anticoagulation level is important for safe initiation of cardiopulmonary bypass. Using the Hemochron Jr., we consistently noted a higher than customary heparin dose required to achieve an activated clotting time (ACT) that, according to the literature and our quality standards, should be more than 480 seconds. This study was designed to determine whether there existed a significant difference in ACT values measured by the newer Hemochron Jr. and the older Hemochron 801 assay system. METHODS: A total of 30 patients underwent cardiovascular surgical procedures requiring heparinization (300 U/kg). Multiple samples for measurement of the ACT were obtained from all patients before heparinization, after heparinization, during cardiopulmonary bypass, and after protamine administration. Arterial samples were collected, and ACT was determined simultaneously on the same sample using both Hemochron Jr. and Hemochron 801. Activated clotting time data were analyzed with a linear mixed model using an unstructured variance-covariance matrix. RESULTS: Descriptive statistics on all heparinized patients revealed that the Hemochron Jr. yielded ACT results that on average were 121.28 seconds lower than the determination by the standard Hemochron 801 on the same sample of blood. This difference was -139.04 in on-pump cases and -90.51 in off-pump cases, primarily a function of the fact that higher heparin doses and therefore longer ACTs were used in patients having operations using the heart-lung machine. From the linear mixed model, the estimated average paired difference between the Hemochron Jr. and Hemochron 801 was found to be -86.03, yielding a highly significant test statistic (t(28) = -6.18; p < 0.0001). CONCLUSIONS: Lower ACT values determined by Hemochron Jr. are consistent with higher, clinically acceptable ACT values as measured by the Hemochron 801. These findings would suggest that safe levels of anticoagulation are determined in part by the specific assay used.

Blood Coagulation Tests↗

Evaluation of the H-point standard additions method (HPSAM) and the generalized H-point standard additions method (GHPSAM) for the UV-analysis of two-component mixtures.

The H-point standard additions method (HPSAM) and two versions of the generalized H-point standard additions method (GHPSAM) are evaluated for the UV-analysis of two-component mixtures. Synthetic mixtures of anhydrous caffeine and phenazone as well as of atovaquone and proguanil hydrochloride were used. Furthermore, the method was applied to pharmaceutical formulations that contain these compounds as active drug substances. This paper shows both the difficulties that are related to the methods and the conditions by which acceptable results can be obtained.

Anti-Inflammatory Agents, Non-Steroidal↗

Paper standard gamble: a paper-based measure of standard gamble utility for current health.

OBJECTIVES: To develop and validate a paper-based instrument that is simple to administer and produces a reliable estimate of patient standard gamble (SG) utilities for current health status. METHODS: A 1-page paper questionnaire instrument, paper standard gamble (PSG), was designed to estimate SG utilities. We performed two studies to assess the validity of PSG. First we compared PSG and SG utilities for current health in patients with prostate cancer. They randomly received either PSG followed by SG or vice versa, always with an intervening SF-12. In the second validity study, we assessed the test-retest reliability of PSG by administering it to prostate cancer patients twice, at least 2 weeks apart. RESULTS: In the first study, utilities were assessed in 64 men (32 per SG/PSG order group). A paired-comparison t test suggested no difference between SG and PSG (mean difference = -0.007; 95% confidence interval (Cl), -0.022 to 0.008). The concordance correlation coefficient was 0.92 (95% Cl, 0.79 to 0.99). In the second study, test and retest PSGs were available for 184 patients. The concordance correlation coefficient was 0.88 (95% Cl, 0.73 to 0.94). CONCLUSIONS: These data suggest that PSG may serve as a reliable substitute for SG when current health utility is of interest. PSG may have particular advantages for acquisition of health-related quality-of-life data in longitudinal studies.

Aged↗

Changes in rowing ergometer, weight lifting, vertical jump and isokinetic performance in response to standard and standard plus plyometric training programs.

The purpose of this study was to compare standard (S-weight plus rowing ergometer training) and standard plus plyometric (S+P-weight plus rowing ergometer training, plus plyometric exercises) programs on sport-specific and non sport-specific tests. Twenty-four female rowers completed the weight training or the weight training plus plyometric exercises three times per week and rowing ergometer training four times per week, 1 hr per session for 9 wks. Analysis of variance tests were used to compare S (n = 11; 5 novice and 6 experienced rowers) and S+P (n = 13; 7 novice and 6 experienced rowers) programs on the following sport-specific tests: 1) time to row 2,500 m and 2) distance rowed in 90 s; and on the following non sport-specific tests: 1) leg press, 1 RM, 2) leg press endurance, 3) bench pull 1 RM, 4) bench pull endurance, 5) vertical jump, 6-9) isokinetic knee extensor peak and average power during concentric and eccentric muscle actions and 10) angle of occurrence of peak torque during concentric muscle actions (isokinetic knee extension). Although experienced oarswomen scored significantly higher than did novice oarswomen on eight of 12 tests (p < 0.04), both levels of rower responded similarly to training. No significant differences were observed post-training between the S and S+P training programs (p > 0.05). These results do not discount the value of plyometric exercises, but indicate that the jump exercises used offered no advantages to intercollegiate oarswomen.

Body Weight↗