Diagnosis with spiral CT imaging before gastric carcinoma surgery

This study was carried out to study multi-slice spiral CT imaging for patients with gastric carcinoma and explore the values of multi-slice spiral CT imaging in staging prior to gastric carcinoma (GC) surgery. Forty-eight patients with GC underwent multi-slice spiral CT, and the scanning results were compared with the pathological results. The similarity of the results was observed, and the accuracy was calculated. Of 48 patients, 8 did not undergo surgery because of metastasis. In the diagnosis of the remaining 40 patients, the sensitivity of multi-slice spiral CT in the diagnosis of staging of invasive depth of GC was 77.5%; κ = 0.642 in the analysis of consistency; there was no significant difference with the pathological results (p >0.05). The overall accuracy of diagnosis for stage N was 80%. The accuracy of multi-slice CT in detecting distant metastasis of GC was 87.5%. Multi-slice spiral CT can determine and evaluate various metastases of GC. The diagnostic results obtained using multi-slice spiral CT was probably consistent with the pathological results.

[Effects of composition of mobile phases on retention behavior of solutes in hydrophobic interaction chromatography]

The retention behavior of aromatic alcohol homologues in hydrophobic interaction chromatography (HIC) was investigated for the first time. The differences in retention behavior between proteins and small solutes, and the eluted range and ability of different salts to small solutes and biopolymers, are elucidated with the parameter Z of the stoichiometric displacement retention model. The retention of aromatic alcohols follows the homologue rule. By the comparison of the changes of Z in different salt solutions, it is found that for small molecules the salt type only changes the hydration degree; but for proteins, it not only changes the hydration of proteins and stationary phase, but also affects the conformation of protein molecules near the contact regions between the protein and the stationary phase surface.

[Study on optimization of the required amount of mobile phase for preparative unit of simultaneous renaturation and purification of proteins]

Based on the stoichiometric displacement model for retention (SDM-R) in high performance liquid chromatography(HPLC), the biopolymer retentions are mainly dominated by displacer's concentration in mobile phase. According to this conclusion, an equation is presented for evaluating the minimum amount of mobile phase used for the preparative purpose with the unit of simultaneous renaturation and purification of proteins (USRPP) by linear gradient elution. Furthermore, the resolution and refolding efficiency of lysozyme were found to be independent of the flow-rate and gradient time when the amount of mobile phase was kept constant. The conclusions were tested by experiments and a good coincidence was obtained.

[Study on quantitative relationship between retention parameters of solutes in reversed-phase liquid chromatography]

A quantitative relationship between lg I (a constant relating to the affinity of one mole of solute to stationary phase) and Z (total moles of organic solvent released at the contact region as one mole solute adsorbed by stationary phase) in the stoichiometric displacement model for retention (SDM-R) of solute was compared with the corresponding relationship in Snyder's Equation in reversed-phase liquid chromatography (RPLC). It was found that the relationship from SDM-R was more exact than that from Snyder's Equation. The linearity depends on the ranges of both lg I and lg Kw0. The broader the range, the better the linearity is. This conclusion conflicts to that reported in references in which the linearity only exists either when one factor dominates solute retention, or when it is completely dominated by statistics. The linear relationship in SDM-R and in Snyder's Equation was found valid not only for homologues but also for non-homologues.

[Study on the rule of solvent strength in reversed-phase liquid chromatography]

Based on the physical meanings of Z (total moles of the released solvent at the contact region between solute and stationary phase), and j(the slope of the linear plot of lg I versus Z, a constant relating to the affinity of organic solvent to the stationary phase) of stoichiometric displacement model for retention (SDM-R) of solute in liquid chromatography(LC), both Z and j could be employed to characterize solvents, therefore, Z value only can be used as a characterization parameter for fixed solute and stationary phase. However, the parameter j is independent of solutes. As long as phase is given, j can be employed as a new characterization parameter of organic solvent strength in LC. With the homologues of methanol, ethanol and n-propanol as organic solvents in mobile phase and n-alkylalcohols as solutes, both the SDM-R and Snyder's empirical equation were tested, and compared with the corresponding parameters obtained from Snyder's empirical equation. With S [the slope of the linear plot of lg k' (k' is capacity factor) vs psi(volume fraction of organic solvent in mobile phase)] and lg kw0(the intercept of this plot), it was found that the two linear plots with the SDM-R, lg k' vs the composition of mobile phase and lg I vs Z were better than the corresponding plots with Snyder's empirical equation. The results indicate that Z, lg I and j decrease with the increase in the molecular size of the organic solvent of the homologue. This fact indicates that the solvent strength in LC depends on the size of solvent molecules. And the greater the solvent molecules, the stronger the solvent strength is. Furthermore the solvent strength was found to follow homologous rule. The j value may become a new parameter for the characterization of organic solvent strength in LC.

[Studies on retention behaviour of biopolymers on silica-based binding stationary phase in the mobile phase of acetic acid-water]

The reversed-phase chromatographic method consisting of acetic acid-water as a new mobile phase for separating biopolymers on ODS column is presented. The new mobile phase may overcome the weak points of irreversible adsorption in chromatographic separation to some degree and difficulty in concentrating proteins with lyophylization and reduce the three-component (organic solvent, ion-pairing agent and water) of typical mobile phase to two component system. Based on the retention and Z (the number of solvent molecules involving in the displacement from stationary-phase surface), log I (a constant relating to the affinity of 1 mol of solute to the bonded stationary phase), and j (a constant relating to the affinity of 1 mol of solvent to the bonded stationary phase), the elution strength of acetic acid-water mobile phase was found to be stronger than that of methanol-water-TFA. From a good linear relationship between log I and Z, it can be concluded that the interaction force between proteins and RPLC stationary phase with acetic acid-water as mobile phase is non-selective hydrophobic interaction forces. In addition, the molecular conformations of protein in acetic acid-water and methanol-trifluoroacetic acid-water were found to be different.

[Thermodynamic characteristics of stoichiometric displacement linear parameter log I in reversed-phase liquid chromatography]

Based on the physical meaning of each term in the linear parameter log I (a constant correlating the affinity of solute to stationary phase) of stoichiometric displacement model for retention(SDM-R) of solute, the thermodynamic characteristics of log I of solute in reversed-phase liquid chromatography (RPLC) were investigated theoretically. This point was tested by experimental data with two linear relationships: (1) plot of log I vs 1/T (T is absolute temperature) with apolar, polar small solutes and proteins; (2) plot of log I vs log Po/w (partition coefficient of solute between n-octanol and water) with apolar and polar small solutes. From the comparison of the magnitude of partition coefficient between small solute and proteins, a phenomenon that the resolution of small solutes depends on column length but that of proteins almost to be independent of column length is quantitatively explained.

[The application of liquid chromatography in genetic engineering]

The recent development of the molecular conformation, renaturation and intermediates on therapeutic proteins produced in biotechnology is reviewed. It also includs the quality control and in preparation of the therapeutic proteins in large scale by liquid chromatography in down-stream technology. This review includes 42 references.