Analytical performance and comparability of the determination of cholesterol by 12 Lipid-Research Clinics.

1977 ◽  
Vol 23 (9) ◽  
pp. 1744-1752 ◽  
Author(s):  
K Lippel ◽  
S Ahmed ◽  
J J Albers ◽  
P Bachorik ◽  
G Cooper ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Lipid Research Clinic ◽  
Cholesterol Concentration ◽  
Entire Group ◽  
Lipid Research ◽  
Collaborative Studies ◽  
Control Serum ◽  
Control Procedures ◽  
And Control

Abstract Twelve Lipid-Research Clinic laboratories performed automated cholesterol analyses on four control-serum pools of known cholesterol concentration, using the Liebermann-Burchard reaction. The analyses were done during a two-year period, with the same standards, methodology, and quality-control procedures. Estimates of analytical bias, variability, and short- and long-term trends for each instrument and for the entire group of LRC instruments are presented. High accuracy, precision, and interlaboratory comparability were achieved through the rigorous standardization and control of the entire analytical procedure. The significance of these results for long-term collaborative studies is discussed. Individual laboratory biases averaged from 0.5 to 2.0% below Abell-Kendall reference values. Between-run variability was about equal to within-run variability and inter-laboratory variation was substantially less than intra-laboratory variation. The total standard deviation for all instruments was about 0.04 g/liter. Only 8-15% of this variation was due to differences between instruments. The between-instrument standard deviation ranged from 0.011 to 0.015 g/liter; the between-run, within-instrument standard deviation ranged from 0.023 to 0.030 g/liter; and within-run standard deviation ranged from 0.023 to 0.028 g/liter. The significance of the achieved results for long-term collaborative studies is discussed.

Analytical performance and comparability of the determination of triglycerides by 12 Lipid Research Clinic laboratories.

1978 ◽  
Vol 24 (2) ◽  
pp. 330-338 ◽  
Author(s):  
S Ahmed ◽  
K Lippel ◽  
P Bachorik ◽  
J Albers ◽  
J Williams ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Lipid Research Clinic ◽  
Entire Group ◽  
Lipid Research ◽  
Collaborative Studies ◽  
Control Serum ◽  
Control Procedures ◽  
Long Term Trends ◽  
And Control

Abstract Twelve Lipid Research Clinic laboratories performed automated fluorometric triglyceride analyses on four control serum pools of known concentration by a modified Hantzsch reaction. The analyses were done during a two-year period, with use of common standards, methodology, and quality-control procedures. Estimates of analytical bias, variability, and short- and long-term trends for each instrument and for the entire group of LRC instruments are presented. High accuracy, precision, and interlaboratory comparability were achieved through rigorous standardization and control of the entire analytical procedure. Individual instrument biases varied from an average of 4.9% below to 1.0% above reference values. Between-run variability was often less than within-run variability and interlaboratory variation was substantially less than intralaboratory variation. The total standard deviation for all instruments ranged from 37 to 63 mg/liter. Only 5 to 14% of this variation was due to differences among instruments. The among-instruments standard deviation ranged from 12 to 17 mg/liter; the between-run, within-instrument standard deviation ranged from 29 to 46 mg/liter, and within-run standard deviation from 27 to 40 mg/liter. The significance of the results for long-term collaborative studies is discussed.

External quality-control survey of cholesterol analyses performed by 12 lipid research clinics.

1978 ◽  
Vol 24 (9) ◽  
pp. 1477-1484 ◽  
Author(s):  
K Lippel ◽  
S Ahmed ◽  
J J Albers ◽  
P Bachorik ◽  
R Muesing ◽  
...  
Keyword(s):  
Quality Control ◽  
Automated Analysis ◽  
Cholesterol Concentration ◽  
Lipid Research ◽  
External Quality Control ◽  
External Quality ◽  
Accuracy And Precision ◽  
Control Survey ◽  
Report Accuracy

Abstract We report accuracy and precision achieved in the automated analysis for cholesterol in a long-term multilaboratory study, presenting and evaluating the significance of data accumulated by 12 Lipid Research Clinics (LRC's) in the analysis of 18 unknown surveillance pools during three years. The average bias for all pools and for 13 autoAnalyzer II (Technicon Instruments Corp., Tarrytown, N.Y. 10591) instruments in the 12 clinics was -0.41% (range -1.2 to +0.3%), as compared to values established by reference methodology. The regression equation relating observed cholesterol values (y) to reference values (x) was: y = 0.35 + 0.977x. The bias varied from pool to pool (-2.3 to +5.3%), positive biases being observed for pools with cholesterol concentrations less than 1.4 g/liter, and negative biases for those pools with higher concentrations. Total standard deviations ranged between 25 and 75 mg/liter, and total CV's for most individual instruments were between 1 and 3%. Of the variability for a particular pool, less than 20% was due to differences among instruments, and within- and between-run variabilities were approximately equal. These trends were the same as those previously observed [Clin. Chem. 23, 1744 (1977)] in the analysis of bench control pools of known cholesterol concentration.

An enzymatic triglyceride method that is suitable for long-term population studies.

1978 ◽  
Vol 24 (2) ◽  
pp. 326-329 ◽  
Author(s):  
D F Koehler ◽  
B W Steele ◽  
M M Azar ◽  
K Kuba ◽  
M E Dempsey
Keyword(s):  
Correlation Coefficient ◽  
Population Studies ◽  
Lipid Research Clinic ◽  
Lipid Research ◽  
Suitable Alternative ◽  
Clinical Specimens ◽  
Methodological Problems

Abstract An enzymatic triglyceride method has been shown to be a suitable alternative to the Lipid Research Clinics' extraction/fluorometry method in long-term population studies. Correlation of results obtained with this method by this laboratory (y-axis) and by the Minneapolis Lipid Research Clinic Laboratory (x-axis) during a nine-week standardization period produced a curve with an intercept of -72 mg/liter, a slope of 1.019, and a correlation coefficient of r=0.996 (n=47). During this standardization period certain methodological problems were observed and corrected. An increase in background in certain clinical specimens, caused by spontaneous degradation of NADH, was observed, accurately measured, and taken into account when appropriate.

Comparison of estimates of long-term analytical variation derived from subject samples and control serum.

1977 ◽  
Vol 23 (1) ◽  
pp. 100-104 ◽  
Author(s):  
G Z Williams ◽  
E K Harris ◽  
G M Widdowson
Keyword(s):  
Alkaline Phosphatase ◽  
The Other ◽  
Destructive Effect ◽  
Control Serum ◽  
Weekly Sample ◽  
The Difference ◽  
And Control ◽  
Analytical Variation ◽  
Linear Trends

Abstract Variation in the assays of uniform control serum commonly are assumed to represent day-to-day analytical variation. To test this assumption, we compared the differences between results of serum aliquots assayed immediately for 12 constituents and frozen aliquots accumulated and assayed on a single day with the results of control serum variation from the same period. One aliquot of each weekly sample was stored frozen. Eleven subjects were sampled for 12 weeks. Storage at --20 degrees C for 15 weeks had a mild destructive effect on two enzymes in serum. The control serum data revealed significant linear trends in magnesium (upwards) and alkaline phosphatase (downwards) that substantially increased the respective variances. In the other 10 constituents tested, comparison of variances indicated that long-term (weeks) variation in control serum assays is similar to the difference of variation between aliquots assayed immediately and those frozen and assayed at the same time. For these constituents, this finding justifies the use of control serum to estimate long term analytical variation.

Production and Control of Reference Materials for Water Microbiology

1991 ◽  
Vol 24 (2) ◽  
pp. 53-56 ◽  
Author(s):  
K. A. Mooijman ◽  
A. H. Havelaar ◽  
J. A. Hoekstra ◽  
N. G. W. N. van Strijp-Lockefeer
Keyword(s):  
Reference Materials ◽  
Milk Powder ◽  
Contamination Level ◽  
Long Term Stability ◽  
Collaborative Studies ◽  
Water Microbiology ◽  
Challenge Tests ◽  
Short Time ◽  
And Control

Reference materials for water microbiology were prepared by spray-drying milk, artificially contaminated with a known test strain. The resulting highly contaminated milk powder was mixed with sterile milk powder to a contamination level of 2000-3000 cfu/g. Gelatin capsules were filled with the mixture (0.2 g/capsule) to produce the reference materials. Test strains used were: WR1 Escherichia coli, WR3 Enterobacter cloacae, WR63 Enterococcus faecium and WR51 Staphylococcus spec. Optimalization of the mixing procedure and aging of the highly contaminated milk powder resulted in relatively homogeneous and stable reference materials. Short-time challenge tests at “high” temperatures (30 and 37 °C) may be predictive for long-term stability at “low” temperatures (4-6 °C). Reference materials with strain WR3 were stable for one week at 30 °C and for at least 6 months at 4-6 °C. Possible applications of the reference materials are: quality control of routine measurements, comparison of the efficiency of different culturing methods and as a standardized sample in collaborative studies.

Suppressed, but Not Forgotten

2011 ◽  
Vol 70 (1) ◽  
pp. 5-11 ◽  
Author(s):  
Beat Meier ◽  
Anja König ◽  
Samuel Parak ◽  
Katharina Henke
Keyword(s):  
Memory Trace ◽  
Thought Suppression ◽  
Test Phase ◽  
Indirect Test ◽  
Final Test ◽  
Test Experiment ◽  
And Control ◽  
Cue Words ◽  
The Impact

This study investigates the impact of thought suppression over a 1-week interval. In two experiments with 80 university students each, we used the think/no-think paradigm in which participants initially learn a list of word pairs (cue-target associations). Then they were presented with some of the cue words again and should either respond with the target word or avoid thinking about it. In the final test phase, their memory for the initially learned cue-target pairs was tested. In Experiment 1, type of memory test was manipulated (i.e., direct vs. indirect). In Experiment 2, type of no-think instructions was manipulated (i.e., suppress vs. substitute). Overall, our results showed poorer memory for no-think and control items compared to think items across all experiments and conditions. Critically, however, more no-think than control items were remembered after the 1-week interval in the direct, but not in the indirect test (Experiment 1) and with thought suppression, but not thought substitution instructions (Experiment 2). We suggest that during thought suppression a brief reactivation of the learned association may lead to reconsolidation of the memory trace and hence to better retrieval of suppressed than control items in the long term.

Strengthening of occupational health promotion by the German Prevention Health Care Act

2019 ◽  
pp. 188-190
Author(s):  
Diana Hart
Keyword(s):  
Public Health ◽  
Health Care ◽  
Health Promotion ◽  
Primary Prevention ◽  
Occupational Health ◽  
Life Expectancy ◽  
Prevention And Control ◽  
Occupational Health Promotion ◽  
And Control

All countries are faced with the problem of the prevention and control of non-communicable diseases (NCD): implement prevention strategies eff ectively, keep up the momentum with long term benefi ts at the individual and the population level, at the same time tackling hea lth inequalities. Th e aff ordability of therapy and care including innovative therapies is going to be one of the key public health priorities in the years to come. Germany has taken in the prevention and control of NCDs. Germany’s health system has a long history of guaranteeing access to high-quality treatment through universal health care coverage. Th r ough their membership people are entitled to prevention and care services maintaining and restoring their health as well as long term follow-up. Like in many other countries general life expectancy has been increasing steadily in Germany. Currently, the average life expectancy is 83 and 79 years in women and men, respectively. Th e other side of the coin is that population aging is strongly associated with a growing burden of disease from NCDs. Already over 70 percent of all deaths in Germany are caused by four disease entities: cardiovascular disease, cancer, chronic respiratory disease and diabetes. Th ese diseases all share four common risk factors: smoking, alcohol abuse, lack of physical activity and overweight. At the same time, more and more people become long term survivors of disease due to improved therapy and care. Th e German Government and public health decision makers are aware of the need for action and have responded by initiating and implementing a wide spectrum of activities. One instrument by strengthening primary prevention is the Prevention Health Care Act. Its overarching aim is to prevent NCDs before they can manifest themselves by strengthening primary prevention and health promotion in diff erent sett ings. One of the main emphasis of the Prevention Health Care Act is the occupational health promotion at the workplace.

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