Advia 1650 system

Serum high-sensitivity C-reactive protein (hs-CRP) was measured with an ADVIA 1650 system (Bayer, Tarrytown, NY, USA) using a commercially available, high-sensitivity CRP-Latex(II) X2 kit (Seiken Laboratories Ltd., Tokyo, Japan), which allows detection of CRP in the 0.001–31 mg/dL range, as described in a previous report [31 (link)]. Plasma concentrations of interleukin-6 (IL-6), IL-1β, and tumor necrosis factor-α (TNF-α) were measured using the Quantikine® HS ELISA Kit (R&D systems, Inc., Minneapolis, MN, USA), according to the manufacturer's instructions. The resulting color reaction was measured using the iMark™ microplate absorbance reader (Bio-Rad Laboratories, Hercules, CA, USA). The wavelength correction was set to 490 and 560 nm.

Plasma oxidized LDL (oxLDL) was measured using an enzyme immunoassay (Mercodia, Uppsala, Sweden). The resulting color reaction was measured using the iMark™ microplate absorbance reader (Bio-Rad Laboratories, Hercules, CA, USA). The wavelength correction was set to 450 nm and 540 nm. Serum high-sensitivity C-reactive protein (hs-CRP) was measured with an ADVIA 1650 system (Bayer, Tarrytown, NY, USA) using a commercially available, high-sensitivity CRP-Latex(II) X2 kit (Seiken Laboratories Ltd., Tokyo, Japan). Plasma tumor necrosis factor-α (TNF-α) was measured using human Quantikine HS ELISA Kit (R&D system, Minneapolis, MN USA). The resulting color reaction was measured using the iMark microplate absorbance reader (Bio-Rad Laboratories, Hercules, CA, USA). The wavelength correction was set to 490 nm and 560 nm. White blood cell counts were determined using the HORIBA ABX diagnostic (HORIBA ABX SAS, Parc Euromedicine, France).

Body fat was measured with a dual-energy X-ray absorptiometer (QDR 4500A; Hologic Inc., Waltham, MA, USA). Well-trained observers manually measured blood pressure with a mercury sphygmomanometer (Baumanometer; Baum, Copiague, NY, USA). During the survey, a random urine sample was collected. All samples were refrigerated and transported to the central laboratory within 24 h. Urinary sodium levels were measured using the ion-selective electrode method. Serum and urine creatinine levels were assessed with the Jaffe reaction and measured with an automatic analyzer (ADVIA 1650 system; Bayer Health Care, Tarrytown, NY, USA). Blood samples were immediately refrigerated, transported to the Central Testing Institute in Seoul, Korea, and analyzed within 24 h. The serum levels of creatinine and the lipid and liver enzyme profiles were determined using a Hitachi 7600 automated chemistry analyzer (Hitachi, Tokyo, Japan) using the indicated methods. Fasting insulin (INS-IRMA; Biosource, Nivelles, Belgium) was measured by an immunoradiometric assay. Homeostasis model assessment of insulin resistance (HOMA-IR) values were calculated using the following formula: fasting [plasma glucose (mg/dL) × fasting insulin (mIU/mL)]/22.5 [15 (link)].