Value of Golgi protein 73 monoclonal antibody in diagnosis of hepatocellular carcinoma / 中国医学科学院学报

<p><b>OBJECTIVE</b>To explore the sensitivity and specificity of Golgi protein 73 (GP73) monoclonal antibody in the diagnosis of hepatocellular carcinoma (HCC).</p><p><b>METHODS</b>Self-prepared GP73 monoclonal antibody was used as the primary antibody for detecting the serum GP73 levels in healthy controls(n=31)and HCC patients (n=59). The baseline level of the healthy controls was determined by semiquantitative analysis. The results were compared with those from GP73 polyclonal antibody and alpha-fetoprotein (AFP).</p><p><b>RESULTS</b>The GP73 level of healthy controls was 1.2 (0.9-1.7) relative unit (RU), which was significantly lower than that of HCC patients [5.7 (2.5-7.8) RU] (P<0.001) with monoclonal antibody. Using polyclonal antibody, the GP73 level of HCC patients was also significantly higher than healthy controls [7.8 (3.0-12.4) RU vs. 1.1 (1.0-2.0) RU, P<0.001]. The sensitivity and specificity of GP73 monoclonal antibody in diagnosis of HCC were 84.7% and 93.5%; on the contrary, those of GP73 polyclonal antibody were 78.0% and 93.5%, respectively. The sensitivity and specificity of AFP (67.8% and 74.2%, respectively) in the HCC patients were markedly lower than those of GP73. Logistic regression analysis showed that the odds ratio (OR) of GP73 monoclonal antibody was 7.18 and that of GP73 polyclonal antibody was 1.51.</p><p><b>CONCLUSIONS</b>Our self-prepared monoclonal antibody can effectively detect GP73 serum level in HCC patients, and has higher sensitivity and specificity than AFP. It may be superior to the currently used GP73 polyclonal antibody. The results lay the foundation for the further development of ELISA methods by using this monoclonal antibody.</p>

Glycosylation-induced depolarization facilitates subthreshold membrane oscillation in injured primary sensory neurons.

Subthreshold membrane potential oscillations (SMPO) in the injured dorsal root ganglion (DRG) neurons are involved in the generation of spontaneous activity, which can directly evoke neuropathic pain. Nerve injury usually triggers the synthesis of large quantities of membrane protein in nerve injured DRG neurons. Membrane proteins are glycosylated by addition of sugars, especially negatively charged sialic acid residues, which may depolarize the resting membrane potential (Vm), open voltage-gated channels in injured neurons, and cause spontaneous activity. In the present study, we aimed to determine if increased negative charge on the cell surface, carried by the sialic acid residues, could contribute to the generation of SMPO in injured DRG neurons. Intracellular recording was performed in DRG neurons following chronic constrictive injury (CCI) of the sciatic nerve. Results indicated that both A- and C-type injured DRG neurons exhibited a higher incidence of SMPO and more depolarized Vm than those of the control neurons. Ca(2+), Mg(2+), Mn(2+), or poly-lysine, a positively charged organic compound, when topically applied to the DRG, not only reduced SMPO but also caused a rapid hyperpolarizing shift in Vm. Topical application of neuraminidase to selectively remove sialic acid residues on the extracellular membrane normalized the depolarized Vm and inhibited both spontaneous and evoked SMPO. However, application of Ca(2+), Mg(2+), Mn(2+) or neuraminidase had no effect on excitability and Vm in normal neurons. The results demonstrated that the increase in negatively charged sialic acid residues on the extracellular membrane of neuronal somata is a critical factor in the generation of SMPO and hyperexcitability in injured sensory neurons.

Sialic acid contributes to generation of ectopic spontaneous discharges in rats with neuropathic pain.

Ectopic spontaneous discharges (ESD) of teased myelinated fibers were recorded from the sciatic nerve proximal to the site of 'chronic constriction nerve injury' in the rat. Ca(2+), Mg(2+), Mn(2+), Ni(2+), La(3+) and some positively charged organic compounds (hexamethonium and poly-lysine) when applied topically to the injured site abolished or significantly reduced the rate of ESD. After enzymatic removal of sialic acid by neuraminidase (2 units/ml), the ESD was silenced in 11, reduced in four and unchanged in four of 19 fibers. However, divalent cations failed to depress the reappeared ESD evoked by 4-aminopyridine in the desialylated silenced fibers. Moreover, the mean incidence of ESD was significantly reduced after neuraminidase treatment. These results indicate that an increase in negative charges on the external membrane surface of injured neuron caused by sialylation is a key factor in ESD generation.