The Effects of Long-term Storage on Commonly Measured Serum Analyte Levels.

BACKGROUND: Cohort studies typically bank biospecimens for many years before assay and investigators do not know whether levels of analytes have degraded. METHODS: We collected control samples from 22 nonstudy participants using the same enrollment criteria and specimen collection, processing, and storage protocols as The Sister Study. Serum samples were assayed for 21 analytes at collection and 6 years later. For each sample, the difference between the result at baseline and at 6 years was calculated for each analyte. RESULTS: Some of the analytes experienced a marked decrease in concentration after 6 years of frozen storage in liquid nitrogen vapor, compared with their baseline value. The confidence interval for the mean paired difference excluded 0 for 8 of the 21 analytes tested (aspartate transaminase, total cholesterol, estradiol, glucose, high-density lipoprotein [HDL] cholesterol, luteinizing hormone, protein, and triglycerides). Two analytes, lactate dehydrogenase and sex hormone binding globulin, increased substantially in concentration over time (confidence interval excluded 0). For compounds substantially affected by storage time, the internal laboratory control variance was greater than the estimated mean percent change for HDL cholesterol and luteinizing hormone, indicating that extent of degradation for these analytes did not exceed technical variation. CONCLUSIONS: Despite evidence for systematic changes over long-term storage, correlations between baseline and later measures were high with little relation between size of the correlation and estimated mean difference across time points. QC experiments to assess the impact of long-term storage on anticipated analytes of interest are important in planning cohort studies with banked samples.

A Biospecimen Proficiency Testing Program for Biobank Accreditation: Four Years of Experience.

Biobanks produce and distribute biospecimens, ensuring their fitness for purpose and accurately qualifying them before distribution. In their efforts toward professionalization, biobanks can nowadays seek certification or accreditation. One of the requirements of these standards is regular participation in Proficiency Testing (PT) programs. An international PT program has been developed and provided to biobanks and other laboratories that perform specific tests to qualify different types of biospecimens. This PT program includes biospecimen testing schemes, as well as biospecimen processing interlaboratory exercises. This PT program supports the development of biobank quality assurance by providing the possibility to assess biobank laboratory performance and useful insights into biobank laboratory method performance characteristics and thus fulfill the demands from accreditation authorities.

Assays for Qualification and Quality Stratification of Clinical Biospecimens Used in Research: A Technical Report from the ISBER Biospecimen Science Working Group.

This technical report presents quality control (QC) assays that can be performed in order to qualify clinical biospecimens that have been biobanked for use in research. Some QC assays are specific to a disease area. Some QC assays are specific to a particular downstream analytical platform. When such a qualification is not possible, QC assays are presented that can be performed to stratify clinical biospecimens according to their biomolecular quality.

Repository Planning, Design, and Engineering: Part I--Infrastructure.

This is a two-part review describing the planning, engineering, and design considerations for building a new repository for biological and environmental samples. Part I addresses the physical infrastructure requirements for a repository; Part II will cover equipment and costing. Planning for construction of a new repository is a complex process requiring comprehensive preplanning and adherence to many regulatory and safety requirements. Guidance and a planning timeline are provided for many of the physical aspects and large capital acquisition costs for the expansion of an existing repository, or the creation of a new repository facility, using an available unoccupied building such as a former warehouse. This article provides a comprehensive set of information about every aspect of repository construction and operation to be considered in the planning process, and also addresses all aspects of designing and constructing a new repository in an existing structure. The engineering and design parameters for the repository are discussed in detail.

Repository Planning, Design, and Engineering: Part II-Equipment and Costing.

Part II of this article discusses and provides guidance on the equipment and systems necessary to operate a repository. The various types of storage equipment and monitoring and support systems are presented in detail. While the material focuses on the large repository, the requirements for a small-scale startup are also presented. Cost estimates and a cost model for establishing a repository are presented. The cost model presents an expected range of acquisition costs for the large capital items in developing a repository. A range of 5,000-7,000 ft(2) constructed has been assumed, with 50 frozen storage units, to reflect a successful operation with growth potential. No design or engineering costs, permit or regulatory costs, or smaller items such as the computers, software, furniture, phones, and barcode readers required for operations have been included.

Quality management of biorepositories.

Biomedical investigators require high quality human tissue to support their research; thus, an important aspect of the provision of tissues by biorepositories is the assurance of high quality and consistency of processing specimens. This is best accomplished by a quality management system (QMS). This article describes the basis of a QMS program designed to aid biorepositories that want to improve their operations. In 1983, the UAB Tissue Collection and Biobanking Facility (TCBF) introduced a QMS program focused on providing solid tissues to support a wide range of research; this QMS included a quality control examination of the specific specimens provided for research. Similarly, the Division of Laboratory Sciences at the Centers for Disease Control and Prevention (CDC) introduced a QMS program for their laboratory analyses, focused primarily on bodily fluids. The authors of this article bring together the experience of the QMS programs at these two sites to facilitate the development or improvement of quality management systems of a wide range of biorepositories.

Identification of evidence-based biospecimen quality-control tools: a report of the International Society for Biological and Environmental Repositories (ISBER) Biospecimen Science Working Group.

Control of biospecimen quality that is linked to processing is one of the goals of biospecimen science. Consensus is lacking, however, regarding optimal sample quality-control (QC) tools (ie, markers and assays). The aim of this review was to identify QC tools, both for fluid and solid-tissue samples, based on a comprehensive and critical literature review. The most readily applicable tools are those with a known threshold for the preanalytical variation and a known reference range for the QC analyte. Only a few meaningful markers were identified that meet these criteria, such as CD40L for assessing serum exposure at high temperatures and VEGF for assessing serum freeze-thawing. To fully assess biospecimen quality, multiple QC markers are needed. Here we present the most promising biospecimen QC tools that were identified.

Standard preanalytical coding for biospecimens: review and implementation of the Sample PREanalytical Code (SPREC).

The first version of the Standard PREanalytical Code (SPREC) was developed in 2009 by the International Society for Biological and Environmental Repositories (ISBER) Biospecimen Science Working Group to facilitate documentation and communication of the most important preanalytical quality parameters of different types of biospecimens used for research. This same Working Group has now updated the SPREC to version 2.0, presented here, so that it contains more options to allow for recent technological developments. Existing elements have been fine tuned. An interface to the Biospecimen Reporting for Improved Study Quality (BRISQ) has been defined, and informatics solutions for SPREC implementation have been developed. A glossary with SPREC-related definitions has also been added.

Standard preanalytical coding for biospecimens: defining the sample PREanalytical code.

BACKGROUND: Management and traceability of biospecimen preanalytical variations are necessary to provide effective and efficient interconnectivity and interoperability between Biobanks. METHODS: Therefore, the International Society for Biological and Environmental Repositories Biospecimen Science Working Group developed a "Standard PREanalytical Code" (SPREC) that identifies the main preanalytical factors of clinical fluid and solid biospecimens and their simple derivatives. RESULTS: The SPREC is easy to implement and can be integrated into Biobank quality management systems and databases. It can also be extended to nonhuman biorepository areas. Its flexibility allows integration of new novel technological developments in future versions. SPREC version 01 is presented in this article. CONCLUSIONS AND IMPACT: Implementation of the SPREC is expected to facilitate and consolidate international multicenter biomarker identification research and biospecimen research in the clinical Biobank environment.

Unexplained decline in the prevalence of anemia among US children and women between 1988-1994 and 1999-2002.

BACKGROUND: The current anemia burden among US preschool children and women of childbearing age has not been documented. OBJECTIVE: We used data from National Health and Nutrition Examination Surveys 1988-1994 and 1999-2002 to examine recent anemia changes. DESIGN: We calculated the prevalence of anemia (hemoglobin < 11.0 g/dL at <24 mo, <11.1 g/dL at 24-59 mo, and <12.0 g/dL for women), iron deficiency anemia (anemia plus abnormal value >or=2: serum ferritin, transferrin saturation, and erythrocyte protoporphyrin), and high blood lead (>or=10 microg/dL) with anemia among children 12-59 mo and women 20-49 y in both surveys. Among women, we also calculated the prevalence of folate deficiency (erythrocyte folate < 317.2 nmol/L) with anemia and high C-reactive protein (>10 mg/L) with anemia. Multiple logistic regression was used to compare anemia prevalence between surveys, with control for race and age. RESULTS: Anemia declined significantly in children (from 8.0% to 3.6%; OR: 0.4; 95% CI: 0.3, 0.7) and women (10.8% to 6.9%; OR: 0.6; CI: 0.4, 0.7), but the prevalence of iron deficiency anemia did not change significantly in children (1.5% compared with 1.2%; OR: 0.7; 95% CI: 0.4, 1.5) or women (4.9% compared with 4.1%; OR: 0.8; 95% CI: 0.6, 1.1). Folate deficiency with anemia declined significantly in women (from 4.1% to 0.5%; OR: 0.1; 95% CI: 0.1, 0.2), but logistic regression models and standardization indicated that none of the known possible anemia causes could account for the decline in total anemia in children or women. CONCLUSIONS: The prevalence of anemia declined significantly among US women and children between 1988-1994 and 1999-2002, but this decline was not associated with changes in iron or folate deficiency, inflammation, or high blood lead.

Homocysteine and vitamin B(12) concentrations and mortality rates in type 2 diabetes.

OBJECTIVE: To assess the role of homocysteine as a risk factor for mortality in diabetic subjects. METHODS: Homocysteine, vitamin B(12), and folate concentrations were measured in stored sera of 396 diabetic Pima Indians aged > or = 40 years when examined between 1982 and 1985. Vital status was assessed through 2001. RESULTS AND CONCLUSIONS: Over a median follow-up of 15.7 years, there were 221 deaths-76 were due to cardiovascular disease (CVD), 36 to diabetes/nephropathy and 34 to infections. Homocysteine was positively associated with mortality from all causes (hazard rate ratio (HRR) for highest versus lowest tertile of homocysteine = 1.70, 95% confidence interval (CI) 1.18-2.46), from diabetes/nephropathy (HRR = 2.39, 95% CI 0.94-6.11) and from infectious diseases (HRR = 3.39, 95% CI 1.19-9.70), but not from CVD (HRR = 1.16, 95% CI 0.62-2.17) after adjustment for age, sex and diabetes duration. Homocysteine correlated with serum creatinine (r = 0.50), and the relationships with mortality rates were not significant after adjustment for creatinine. Vitamin B(12) was positively associated with all-cause mortality (HRR for 100 pg/mL difference adjusted for age, sex and diabetes duration = 1.15, 95% CI 1.08-1.22) and death from diabetes/nephropathy (HRR = 1.27, 95% CI 1.10-1.46). The association between homocysteine and mortality in type 2 diabetes is not causal, but is confounded by renal disease in Pima Indians.

Biochemical indicators of B vitamin status in the US population after folic acid fortification: results from the National Health and Nutrition Examination Survey 1999-2000.

BACKGROUND: Mandatory folic acid fortification of cereal-grain products was introduced in the United States in 1998 to decrease the risk that women will have children with neural tube defects. OBJECTIVE: The objective was to determine the effect of folic acid fortification on concentrations of serum and red blood cell (RBC) folate, serum vitamin B-12, and plasma total homocysteine (tHcy) and methylmalonic acid (MMA) in the US population. DESIGN: Blood was collected from a nationally representative sample of approximately 7300 participants aged > or = 3 y in the National Health and Nutrition Examination Survey (NHANES) during 1999-2000 and was analyzed for these B vitamin-status indicators. The results were compared with findings from the prefortification survey NHANES III (1988-1994). RESULTS: The reference ranges (5th-95th percentiles) were 13.1-74.3 nmol/L for serum folate, 347-1167 nmol/L for RBC folate, and 179-738 pmol/L for serum vitamin B-12. For plasma tHcy and MMA, the reference ranges for serum vitamin B-12-replete participants with normal serum creatinine concentrations were 3.2-10.7 mumol/L and 60-210 nmol/L, respectively. The prevalence of low serum folate concentrations (<6.8 nmol/L) decreased from 16% before to 0.5% after fortification. In elderly persons, the prevalence of high serum folate concentrations (>45.3 nmol/L) increased from 7% before to 38% after fortification; 3% had marginally low serum vitamin B-12 concentrations (<148 pmol/L) and 7% had elevated plasma MMA concentrations (>370 nmol/L). Seventy-eight percent of the US population had plasma tHcy concentrations <9 micromol/L. CONCLUSIONS: Every segment of the US population appears to benefit from folic acid fortification. Continued monitoring of B vitamin concentrations in the US population is warranted.

Hematological and iron-related analytes--reference data for persons aged 1 year and over: United States, 1988-94.

OBJECTIVES: This report presents national estimates of hematologic and iron-related analytes for persons 1 year of age and over, by age, sex, and race/ethnicity. METHODS: The analysis is based on data from the third National Health and Nutrition Examination Survey (NHANES III) (1988-94), which was designed to provide information on the health and nutritional status of the civilian noninstitutionalized U.S. population. The sample used for these analyses included the 26,372 participants who had laboratory tests. RESULTS: This report provides mean, standard error of the mean, median, and percentile laboratory values for the U.S. population, 1988-94, for hematological and iron-related analytes. In addition, percentage distributions are provided. CONCLUSIONS: Data on hematological and iron analytes provide reference values for clinical and longitudinal comparisons.

Selenium and colorectal adenoma: results of a pooled analysis.

BACKGROUND: Secondary analyses of data from a large randomized clinical trial have suggested that intake of the trace element selenium reduces risk of colorectal neoplasia, but epidemiologic studies have not shown a consistent protective association. METHODS: We conducted a combined analysis of data from three randomized trials--the Wheat Bran Fiber Trial, the Polyp Prevention Trial, and the Polyp Prevention Study--which tested the effects of various nutritional interventions for colorectal adenoma prevention among participants who recently had an adenoma removed during colonoscopy. Selenium concentrations were measured from blood specimens from a total of 1763 trial participants, and quartiles of baseline selenium were established from the pooled data. To estimate the association between baseline selenium and colorectal adenoma risk, odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using logistic regression modeling. All statistical tests were two-sided. RESULTS: Individual study results among participants whose blood selenium concentrations were in the highest versus the lowest quartile varied in magnitude (Polyp Prevention Trial: OR = 0.67, 95% CI = 0.43 to 1.05; P(trend) = .21; Wheat Bran Fiber Trial: OR = 0.66, 95% CI = 0.40 to 1.10; P(trend) = .13, and Polyp Prevention Study: OR = 0.57, 95% CI = 0.34 to 0.95, P(trend) = .04). Analyses of the pooled data showed that individuals whose blood selenium values were in the highest quartile (median = 150 ng/mL) had statistically significantly lower odds of developing a new adenoma compared with those in the lowest quartile (OR = 0.66, 95% CI = 0.50 to 0.87; P(trend) = .006). CONCLUSIONS: The inverse association between higher blood selenium concentration and adenoma risk supports previous findings indicating that higher selenium status may be related to decreased risk of colorectal cancer.

Prospective study of serum selenium concentrations and esophageal and gastric cardia cancer, heart disease, stroke, and total death.

BACKGROUND: We previously reported an inverse association between prediagnostic serum selenium concentrations and the risk of esophageal squamous cell carcinoma (ESCC) and gastric cardia cancer (GCC) but not gastric noncardia cancer (GNCC) in a nested study from the Nutrition Intervention Trial in Linxian, China. OBJECTIVE: We examined the relation between baseline serum selenium and the subsequent risk of death from ESCC, GCC, GNCC, heart disease (HD), stroke, and total death over 15 y of follow-up (1986-2001). DESIGN: We measured baseline serum selenium concentrations in 1103 subjects randomly selected from a larger trial cohort. We identified 516 deaths during the 15-y follow up, including 75 from ESCC, 36 from GCC, 116 from HD, and 167 from stroke. Relative risks (RRs) and 95% CIs were estimated by using Cox proportional hazards regression models. Reported RRs estimated the change in risk conferred by a 25% increase in serum selenium relative to the population distribution. All estimates were adjusted for sex, age, smoking, drinking, and serum cholesterol. RESULTS: We found significant inverse associations between baseline serum selenium and death from ESCC (RR: 0.83; 95% CI: 0.71, 0.98) and GCC (0.75; 0.59, 0.95). Trends toward inverse associations were noted for death from HD (0.89; 0.78, 1.01; P = 0.07), but no association was noted for total death (0.96; 0.90, 1.02) or stroke (0.99; 0.88, 1.11). CONCLUSION: Population-wide selenium supplementation in the region of China with low serum selenium and high incidences of ESCC and GCC merits serious consideration.

Determination of folate vitamers in human serum by stable-isotope-dilution tandem mass spectrometry and comparison with radioassay and microbiologic assay.

BACKGROUND: Current clinical methods for folate give different results and cannot measure the various forms of folate. We developed an isotope-dilution tandem mass spectrometric method coupled to liquid chromatography (LC/MS/MS) as a candidate reference method for 5-methyltetrahydrofolic acid (5MeTHF), 5-formyltetrahydrofolic acid (5FoTHF), and folic acid (FA) in human serum. METHODS: We quantitatively isolated folates from 275 microL of serum with a phenyl solid-phase extraction cartridge, then detected and quantified them in stabilized serum extracts by positive-ion electrospray ionization LC/MS/MS. We used an isocratic mobile phase of acetic acid in organic solvent on a C(8) analytical column. (13)C-labeled folates were used as internal standards. RESULTS: Limits of detection in serum were 0.13 (5MeTHF), 0.05 (5FoTHF), and 0.07 (FA) nmol/L. Within- and between-run imprecision (CV) was <7% for 5MeTHF and <10% for 5FoTHF at concentrations >0.5 nmol/L, and <10% for FA at concentrations >2.0 nmol/L. Total folate (TFOL) concentrations determined by competitive protein binding radioassay were approximately 9% lower than results obtained with LC/MS/MS. The microbiologic assay gave approximately 15% higher TFOL results with FA calibrator and no difference with 5MeTHF calibrator. The mean (SD) [range] TFOL in 42 sera was 35.5 (17.8) [6.5-75.6] nmol/L. Thirty-two samples with TFOL <50 nmol/L had, on average, 93.3% 5MeTHF, 2.3% FA, and 4.4% 5FoTHF. Ten samples with TFOL >50 nmol/L had, on average, 81.7% 5MeTHF, 15.7% FA, and 2.5% 5FoTHF. CONCLUSIONS: This stable-isotope-dilution LC/MS/MS method can quantify 5MeTHF, 5FoTHF, and FA in serum. Currently used clinical assays agree with this candidate reference method.

Prospective study of serum vitamin E levels and esophageal and gastric cancers.

Participants in the General Population Trial, a randomized nutrition intervention trial in Linxian, China, who received a combination of selenium, beta-carotene, and vitamin E supplements, had statistically significantly lower cancer mortality rates than those who did not receive the supplements. In the current study, we used a case-cohort design to examine the association between pre-trial serum vitamin E levels and the risks of developing esophageal and gastric cancers during the trial. We measured serum alpha- and gamma-tocopherol and cholesterol levels in 1072 case patients with incident esophageal squamous cell carcinoma (ESCC), gastric cardia cancer (GCC), or gastric noncardia cancer (GNCC) and in 1053 control subjects. The relative risks for comparisons of the highest to the lowest quartiles of serum alpha-tocopherol were 0.63 (95% confidence interval [CI] = 0.44 to 0.91) for ESCC, 0.84 (95% CI = 0.55 to 1.26) for GCC, and 2.05 (95% CI = 0.89 to 4.75) for GNCC. Serum gamma-tocopherol level was not associated with the incidence of any of these cancers. Our findings provide support for the role of alpha-tocopherol in the etiology of upper gastrointestinal cancers.