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Two international apolipoprotein A-1 and B (apoA-1 and apoB) surveys were conducted in 1983 and 1986 with use of a lyophilized serum measured by 55 and 91 participants, respectively. The chief source of variability in both surveys was among laboratories, but among-method variation was significant for apoB. Comparing the 1986 with the 1983 findings, we saw a 60% decrease in apoA-1 variability among laboratories, and a similar decrease (53%) was found for apoB. Evaluation of individual measurements suggests that some collaborators may have adjusted their calibrators toward the consensus values published in 1983.

ConclusionsThe leukocytosis-promoting factor (LPF) of inflammatory exudates when studied electrophoretically in a Tiselius apparatus appears to be distributed primarily between the a and 0.2 globulins of exudates.

The distribution of the ratios of plasma high-density lipoprotein cholesterol (HDL-C) to total cholesterol (TC) and of HDL-C to low-density lipoprotein cholesterol (LDL-C) are presented for 6900 white and 495 black examinees greater than 4 years old. Measurements were obtained during the visit 2 survey of the Lipid Research Clinics (LRC) Program Prevalence Study, and correspond to a 15% random sample of 60,502 participants screened during the LRC visit 1 survey. Age-specific means, medians, and selected percentiles are given by sex and by gonadal hormone use in white women. Apparent in these cross-sectional data was a consistent age-related decline in the ratio of HDL-C to TC for white male participants, from a mean of 0.360 in the age group 5 to 9 to a mean of 0.211 in the age group 50 to 54. Thereafter the mean ratio increased slightly. In white women not using gonadal hormones the age-related decline in the ratio was only evident starting at the age group 35 to 39, from which it declines from 0.329 to 0.258 in the age group 55 to 59. White women using gonadal hormones showed very minor age-related changes in the HDL-C/TC ratio, varying around a mean of 0.300. The number of blacks examined was low and thus the racial comparisons must be interpreted with caution. For each gender, age-related trends were similar in black and white study participants. Black men, however, had a higher percentage of TC carried as HDL-C than white men in all age groups examined. Black women had a higher percentage of TC in HDL-C than white women only below age 20; in the adult age range no appreciable differences were seen. Pearson correlation coefficients between the lipid, lipoprotein, and lipoprotein ratios are presented. The ratio HDL-C/TC correlated highly with the ratio HDL-C/LDL-C (greater than 0.92 for all groups) and the former may be a more conveniently determined surrogate for the latter. Although not exhaustive regarding the information it conveys about a lipid pattern, the ratio HDL-C/TC has the advantage of summarizing complex associations into a single numerical approximation.

Data on the distribution of triglyceride and total, LDL and HDL cholesterol are presented for age groups 40 yr and older. The populations represented came from Framingham, Albany, Honolulu, San Francisco, Evans County and Puerto Rico. They include white, Japanese and black persons and both sexes. Blood samples and lipid measurements were obtained after overnight fast by a common protocol as part of a cooperative study of lipoprotein phenotyping. Means, medians, standard deviations and 95th percentiles are given as well as intercorrelations among the various lipids. Average cholesterol levels ranged from 200 mg/dl (Puerto Rican men) to over 240 mg/dl (Framingham women). Average triglyceride levels ranged from less than 100 mg/dl (Evans County) to an average of 175 mg/dl (Japanese men). For men aged 50–69 triglyceride levels were higher in Puerto Rico than in Albany or Framingham, despite much lower levels of serum cholesterol. The 95th percentile for LDL cholesterol in age groups with at least 100 persons ranged from 196 to 209 mg/dl for men and between 221 and 228 mg/dl for women. The 95th percentile for triglyceride, however, varied greatly by age and population from as low as 249 mg/dl to as high as 451 mg/dl.

The most common biochemical procedures employed in studies on atherosclerosis are those that measure lipids, lipoproteins, and associated metabolic products (1). At present, determinations of cholesterol and triglyceride levels appear to be more useful in the clinical classification of hyperlipidemia and hyperlipoproteinemia and in characterizing the patient with a risk factor. Determination of the lipoprotein concentration and the level of lipoprotein apoproteins and enzymes, however, provides a clearer and more definite picture of the patient’s lipid metabolic state. Other biochemical procedures for plasma constituents, such as hormones, coagulation factors, and constituents associated with other risk factors, are measured to detect or follow suspected risk factors and complications or sequelae of atherosclerosis. Standardization of all of these tests is essential if results obtained by laboratories participating in clinical and epidemiological studies are to be comparable.

(1973). Methods for Determining the Amount of Glucose in Blood. CRC Critical Reviews in Clinical Laboratory Sciences: Vol. 4, No. 2, pp. 101-145.

Results of a one-stage prothrombin time proficiency testing program are reported. Fifty-three participating laboratories using various technics and reagents performed onestage prothrombin time tests on four plasma specimens. These results were compared with determinations performed by eight reference laboratories. Basing acceptability of performance on the reference laboratory data, approximately 80% of participant results were satisfactory. Significant interlaboratory variability in the test results reported in seconds was noted in both reference and participating laboratories. This variability was attributed to differences among thromboplastin reagents and technics of test performance. Presentation of test results as prothrombin ratios (specimen test in seconds/control test in seconds) reduced these differences by partially compensating for the above mentioned variables.

A modification of the Technicon-N-24 method for serum cholesterol is described. It is possible to obtain precise results which agree on the average with those obtained with the reference Abell-Kendall method. The level of cholesterol found by the AutoAnalyzer method depends primarily on the ratio of the rates of flow of the lipid extract to that of the premixed color reagent and the time of heating of the color reaction at 95C. In this modification, the flow rate of isopropyl alcohol extract of sample or standard is kept at 0.9 ml/min and the ratio of flow of extract to that of premixed color reagent is maintained between 1∶10 and 1∶12 while the time of heating of the color reaction is maintained between 95 and 120 sec. Other conditions necessary for precise results are discussed. The precision obtained on the average in several experiments ranged from 2.2 to 2.7 mg% as standard deviation between duplicates.

Publisher Summary Ultracentrifugation and electrophoresis have emerged as the analytical methods of choice for human serum and have contributed a system of nomenclature that is used as a standard for all protein solutions. Ultracentrifugal methodology has progressed through continuous improvement of instruments, techniques, and interpretive procedures, till the use of satisfactory commercially available high-speed ultracentrifuges, both analytical and preparatory, in characterization of human serum proteins. Electrophoresis, an outgrowth of fundamental studies on transference numbers and application to proteins of the moving-boundary phenomena observed in an electric field, has become a procedure of many types. The success of ultracentrifugation and electrophoresis in revealing new components of human serum and other body fluids has at the same time produced problems concerning nomenclature, identification of normal components, and determination of normal values. This chapter discusses electrophoretic analytical methodology and ultracentrifugal analytical methods. In analytical ultracentrifugation, the sedimentation properties of protein particles are measured by either the sedimentation velocity or sedimentation equilibrium methods.

The National Cholesterol Education Program has recommended that all laboratories be consistent, precise, and accurate in the reporting and measurement of blood cholesterol levels. In a follow-up to a 1984 survey study, we assessed the changes in reporting procedures for measurements of blood lipid levels in 16 clinical laboratories in Nebraska. Using human serum reference materials of known cholesterol concentrations provided by the Centers for Disease Control, we also assessed the precision and accuracy of measurement of blood cholesterol levels in clinical laboratories in Nebraska. Fourteen of the 16 laboratories restudied in 1987 had altered the reference range for total serum cholesterol since 1984,86% of whom lowered the upper limit of the reference range. Eleven of 16 laboratories expressed reference ranges for total serum cholesterol in terms of patient age in 1987, while only 7 of 20 did in 1984. Gender-based reference ranges increased from 0 to 5 from 1984 to 1987. Similar trends were seen in the reporting of high-density lipoprotein cholesterol and triglyceride concentrations. Reporting procedures varied greatly; only 1 laboratory used National Cholesterol Education Program risk levels for measuring total serum cholesterol levels. Fifteen laboratories met the National Cholesterol Education Program recommendation for precision (coefficient of variation, ≤5%) and 78% of laboratories obtained results that satisfied the current recommendation for accuracy (within 5% of "true value," as determined by the Centers for Disease Control). ( JAMA . 1989;262:83-88)

Useful laboratory interpretation depends on 3 factors: a valid sample, an accurate method and a specific interpretation. A, valid sample may be affected by a number of conditions. For example, precollection conditions are important. Among the circumstances that influence the precollection condition are the patient’s life-style, diet, exercise and medication, especially diuretics. Intercurrent illness can also alter a patient’s lipid levels; e.g., cholesterol levels drop dramaticaily in the weeks after a myocardial infarction. Several factors that influence collection conditions deserve consideration. For example, if a person is recumbent for 20 minutes before a sample is taken, there can be a 15% change in the cholesterol value. If the tourniquet is applied too tightiy for longer than 2 minutes, a change of 2 to 10% in the value can result. In addition, the anticoagulant used in the vacuum container can dramatically affect the sample. Heparin does not cause any difference between plasma or serum; however, versene causes a 3 to 5% difference. Oxalate creates an 8% difference, and citrate and fluoride can cause changes of as much as 12 and 18%, respectively. When using plasma, a full tube should always be collected. The source of the blood also affects the cholesterol level; there are differences between arterial and venous blood. With regard to laboratory conditions, the measurement will be affected by the handling, storage and shipment of the specimen. In addition, the laboratory should have stable material with which to perform its analysis.

Excerpt Prior to World War II, atherosclerosis was regarded primarily as an aging process, rather than as a disease entity. Although chemical analyses of atheromata by Windaus in 19101revealed thei...

This book is a summary of the proceedings of the conference sponsored by the International Committee for Standardization in Hematology which was held in New York in 1968 and of the International Symposium on Standardization of Hematological Methods held in Milan in 1968. It is a pleasure to find discussions of the work of international experts on quality control and standardization in hematology compiled in one book. The first conference concentrated on the standardization of the determination of hemoglobin because worldwide experiences are now documented and essential basic approaches and requirements have become well delineated. The second conference presented the progress made in other areas of hematology, such as cell counts, coagulation, and enzyme assays. The well thought-out organization of the symposia led to logical presentation of material, problems, and criticisms. Discussion on a given subject is easily located. During the first conference, different international groups critically examined the preparation

A problem of major proportions in the treatment of the secondary aspects of the deeper burns is the presence in the burned area of devitalized or injured tissues. The tissues involved depend on the site and depth of the burn, but for practical purposes the chief component for consideration consists of a mass of interlacing collagen fibers which extend throughout the dermis to connect with like material in the subcutaneous tissue and between the muscle fibers. The material, whether treated with severe coagulatory agents, simple ointments or wet dressings, forms a strongly adherent layer which separates but slowly from the tissues beneath. This layer constitutes a serious impediment to management of the case. Infection is liable to develop within the material or beneath it. Further, even if infection does not occur, the layer may impede healing and preparation of the area for skin grafting. It would appear that occasions might