Identification of clinical biomarkers for pre-analytical quality control of blood samples.

BACKGROUND: Pre-analytical conditions are key factors in maintaining the high quality of biospecimens. They are necessary for accurate reproducibility of experiments in the field of biomarker discovery as well as achieving optimal specificity of laboratory tests for clinical diagnosis. In research at the National Biobank of Korea, we evaluated the impact of pre-analytical conditions on the stability of biobanked blood samples by measuring biochemical analytes commonly used in clinical laboratory tests. METHODS: We measured 10 routine laboratory analytes in serum and plasma samples from healthy donors (n = 50) with a chemistry autoanalyzer (Hitachi 7600-110). The analyte measurements were made at different time courses based on delay of blood fractionation, freezing delay of fractionated serum and plasma samples, and at different cycles (0, 1, 3, 6, 9) of freeze-thawing. Statistically significant changes from the reference sample mean were determined using the repeated-measures ANOVA and the significant change limit (SCL). RESULTS: The serum levels of GGT and LDH were changed significantly depending on both the time interval between blood collection and fractionation and the time interval between fractionation and freezing of serum and plasma samples. The glucose level was most sensitive only to the elapsed time between blood collection and centrifugation for blood fractionation. Based on these findings, a simple formula (glucose decrease by 1.387 mg/dL per hour) was derived to estimate the length of time delay after blood collection. In addition, AST, BUN, GGT, and LDH showed sensitive responses to repeated freeze-thaw cycles of serum and plasma samples. CONCLUSION: These results suggest that GGT and LDH measurements can be used as quality control markers for certain pre-analytical conditions (eg, delayed processing or repeated freeze-thawing) of blood samples which are either directly used in the laboratory tests or stored for future research in the biobank.

Effect of glucose ingestion in plasma markers of inflammation and oxidative stress: analysis of 16 plasma markers from oral glucose tolerance test samples of normal and diabetic patients.

Sixteen plasma markers of inflammation and oxidative stress were measured during OGTT in 54 subjects. Leptin, RBP4, CRP, OPN, ANG, MDC, and MCSF concentrations significantly decreased during OGTT (P<0.05). IL6, IL8, and MCP3 concentrations significantly increased during OGTT (P<0.05). These results provide evidence that glucose ingestion affects systemic inflammation and oxidative stress.

A genome-wide association study identifies a breast cancer risk variant in ERBB4 at 2q34: results from the Seoul Breast Cancer Study.

INTRODUCTION: Although approximately 25 common genetic susceptibility loci have been identified to be independently associated with breast cancer risk through genome-wide association studies (GWAS), the genetic risk variants reported to date only explain a small fraction of the heritability of breast cancer. Furthermore, GWAS-identified loci were primarily identified in women of European descent. METHODS: To evaluate previously identified loci in Korean women and to identify additional novel breast cancer susceptibility variants, we conducted a three-stage GWAS that included 6,322 cases and 5,897 controls. RESULTS: In the validation study using Stage I of the 2,273 cases and 2,052 controls, seven GWAS-identified loci [5q11.2/MAP3K1 (rs889312 and rs16886165), 5p15.2/ROPN1L (rs1092913), 5q12/MRPS30 (rs7716600), 6q25.1/ESR1 (rs2046210 and rs3734802), 8q24.21 (rs1562430), 10q26.13/FGFR2 (rs10736303), and 16q12.1/TOX3 (rs4784227 and rs3803662)] were significantly associated with breast cancer risk in Korean women (Ptrend < 0.05). To identify additional genetic risk variants, we selected the most promising 17 SNPs in Stage I and replicated these SNPs in 2,052 cases and 2,169 controls (Stage II). Four SNPs were further evaluated in 1,997 cases and 1,676 controls (Stage III). SNP rs13393577 at chromosome 2q34, located in the Epidermal Growth Factor Receptor 4 (ERBB4) gene, showed a consistent association with breast cancer risk with combined odds ratios (95% CI) of 1.53 (1.37-1.70) (combined P for trend = 8.8 × 10-14). CONCLUSIONS: This study shows that seven breast cancer susceptibility loci, which were previously identified in European and/or Chinese populations, could be directly replicated in Korean women. Furthermore, this study provides strong evidence implicating rs13393577 at 2q34 as a new risk variant for breast cancer.

Initial effect of an elastic chest band during inspiratory exercise on chest function improvement in people with limited rib mobility: a randomized controlled pilot trial.

BACKGROUND AND PURPOSE: While performing respiratory training, an elastic chest band has great benefits for clinical use due to its safety and easy application. However, to our knowledge, there is no published data on the clinical use of an elastic chest band into inspiratory training for people with limited rib mobility. This study aimed to investigate the effects of an elastic chest band integrated into inspiratory exercise for people with decreased chest function. METHOD: Sixteen subjects with limited rib mobility were randomly assigned to either experimental group (EG) or control group (CG), with eight subjects in each group. All subjects received an inspiratory exercise using incentive spirometer for 30 minutes. For the subjects of the EG, an elastic chest band was incorporated into the inspiratory exercises to provide compressive resistance to the chest. The chest function was measured using an electronic spirometer to determine the vital capacity (VC), tidal volume (TV), inspiratory reserve volume (IRV), expiratory reserve volume, forced vital capacity (FVC), forced expiratory volume (FEV), FEV in 1-second (FEV1) and the ratio of FEV1 to FVC (FEV1 %). RESULTS: Significant differences were found for the VC, TV, IRV, FVC and FEV1 between pre-test and post-test in the two groups (p < 0.05). Further, the changes in the values of VC (0.47 L vs. 0.22 L), FVC (0.55 L vs. 0.25 L) and FEV1 (0.65% vs. 0.21%) in the EG subjects were significantly greater than those in the CG subjects (p < 0.05). CONCLUSIONS: These findings suggest that an elastic chest band combined with inspiratory exercise produces additional positive effect on improving chest function in people with limited rib mobility.

Proteomic analysis of the effect of storage temperature on human serum.

This study examined the effect of storage temperature on the protein profile of human serum. Serum samples were stored for > or =7 days at -80 degrees C, -20 degrees C, 4 degrees C, and room temperature prior to proteomic analysis. Serum protein fractionations by SDS-PAGE, including high and low molecular weight (MW) proteins, showed that several bands had different intensities after storage at higher temperatures. Fractionations by 2-dimensional gel electrophoresis (2-DE) indicated that approximately 60 protein spots had changed significantly after storage at higher temperatures. These proteins included C3/C4, alpha2-macroglobulin, and alpha1B glycoprotein, based on identification by MS and MS/MS. The profile of the low MW serum proteins, analyzed using SELDI ProteinChip Arrays (IMAC3 and Q10), was also significantly changed after storage at higher temperatures. These results indicate that the higher storage temperatures have a significant influence on serum protein profiles regardless of MW. Based on these findings, serum specimens should be preferably be stored at -80 degrees C before proteomic analysis.