SSAO inhibitors suppress hepatocellular tumor growth in mice.

Vascular adhesion protein-1 (VAP-1) is both an endothelial adhesion molecule involved in leukocytes emigration, and an oxidase belonging to the family of semicarbazide-sensitive amine oxidases (SSAOs). The enzyme activity of VAP-1 plays an important role in the migration of myeloid-derived suppressor cells (MDSCs) into tumor site, and SSAO inhibitors can block the function of VAP-1. The effects of SSAO inhibitors on leukocyte infiltration and tumor progression were evaluated in H22 hepatocellular carcinoma-bearing C57BL/6 mice. Tumor weight and volume were measured after SSAO inhibitor treatment. Then, MDSCs recruitment and neo-angiogenesis were determined using immunostaining. SSAO inhibitors significantly blocked the catalytic activity of VAP-1 in tumor, attenuated tumor progression, and reduced neo-angiogenesis. CD11b(+) and Gr-1(+) MDSCs, which normally infiltrate into tumors, were significantly diminished in tumor-bearing mice treated with SSAO inhibitors. The present study demonstrated that SSAO inhibitors might have an anti-tumor effect on hepatocellular carcinoma by inhibiting recruitment of CD11b(+) and Gr-1(+) cells and hindering angiogenesis, which could be attributed to impairing the catalytic activity of VAP-1.

[Determination of trace free copper and zinc in serum samples by graphite furnace atomic absorption spectrometry after two-step precipitation of protein].

A method was developed for the determination of trace free copper and zinc in serum sample by GFAAS after two-step precipitation. The serum and ethanol were mixed with volume ratio of 1 : 2. The mixture was subsequently denatured at 70 degrees C and centrifuged to precipitate proteins. The determination, limit of copper (3sigma) was 1.2 microg x L(-1) and the recovery was 92.3% - 104%, and the determination. Limit of zinc(3sigma) was 0.098 microg x L(-1) and the recovery was 90%-107%. This two-step precipitation method can be used to determine non-protein-bound copper in tumor patients and healthy people.

[Study of protein conformation in solution by tyrosine residues RRS spectrum].

Due to the interference caused by the emission of tryptophan residue, it is hard to use fluorospectrophotometry to detect the spectrometric changes of the tyrosine residue when protein conformation is changed. When the concentration of protein in solution is relatively high, tyrosine residue has a characteristic scattering peak when excited with its K-band wavelength of light. In the present study, the authors established a method for detecting protein conformation changes in solution through the changes (peak height and wavelength shift) of the characteristic scattering peak of tyrosine residue. The method may be used for detecting protein conformation changes in solution caused by the changes of electrolyte, pH, and temperature.