The protocol for evaluation of β-end in plasma was performed according to the guidelines in β-end ELISA kit (Catalog Number EDRF.96, MD Biosciences, Inc. USA). 500 μl of plasma was acidified with 500 μl of 1% trifluoroacetic acid (TFA) and mixed, then centrifuged at 10,000 × g for 20 min at 4degrees C. We then equilibrated a SEP-Column (200 mg of C18) by washing with 60% acetonitrite in 1% TFA (1,000 μl) followed 3 times with 1% trifluoroacetic acid (3000 μl). We loaded the acidified plasma solution onto the pre-treated C-18 SEP- Column, slowly washed the column with 1% trifluoroacetic acid and collected eluant. We evaporated the eluant to dryness in a centrifugal concentrator and collected this in a polypropylene tube and kept he dried sample at -20 degress C. In the ELISA system, the dried sample was reconstituted with assay buffer and a 50 μl of sample, 25 μl of primary anti-serum, and 25 μl of biotinlyated β-end was loaded into each wells. After incubation for 2 hr at room temperature, wells were washed washed three times, and dried. We then added 100 μl of diluted SA-HRP solution in each well, except for the blank, and incubated for 1 hr at room temperature. The plate was washed again three times and dried. Finally, we added 100 μl of TMB solution to each well, and incubated for 1 hr at room temperature. The reaction was stopped with 2N HCL and absorbance read at 450 nm. The concentration of β-end was calculated with the standard curve of standard β-end (0.01-1,000 ng/mL).