重庆市低收入群体子女教育消费内部结构分析

本文以低收入群体的教育消费为研究对象,对重庆市低收入群体教育消费内部结构、水平进行数量分析,在此 基础上,进行比较分析,研究重庆市低收入群体教育消费的水平和结构等现状特征和表现,提出改善低收入群体教育消费的 政策建议。

Assessment of hepatocellular carcinoma vascularity before and after transcatheter arterial chemoembolization by using first pass perfusion weighted MR imaging

AIM:To assess the vascularity of hepatocellular carcinoma (HCC) before and after transcatheter arterial chemoembolization (TACE) with the quantitative parameters obtained by first pass perfusion weighted MR imaging (FP-MRI). METHODS:Seventeen consecutive patients with one to three lesions in liver underwent FP-MRI before treatment. FP-MRI was also performed one,three,six,nine months, and one year after TACE.The baseline signal intensity (SO) of pre-TACE and one month after TACE was analyzed,the vascularity of HCC assessed by steepest slope of the signal intensity versus time curves (SS) was blindly correlated with their DSA feature and clinical outcome. RESULT:No significant difference was found on baseline signal intensity (S0) between pre-TACE and one month after TACE (F=0.309,P=0.583),The SS (mean,32% per second) of lesion one month after TACE was lower than that of pre-TACE (mean,69% per second),but with no statistical significance (F=3.067,P=0.092).When local recurrence occurred,the time intensity curves became steeper.The vascularity of HCC before and after TACE graded by SS closely correlated with that by DSA (K=0.453,P<0.05). CONCLUSION:FP-MRI is a useful criterion for selecting effective interventional treatment for patients with HCC in their initial treatment and during follow up.

Changes of tumor microcirculation after transcatheter arterial chemoembolization:First pass perfusion MR imaging and Chinese ink casting in a rabbit model

AIM: To observe the change of tumor microcirculation after transcatheter arterial chemoembolization (TACE) with bletilla microspheres by using first pass perfusion MR imaging (FP) and Chinese ink casting.METHODS: VX2 carcinoma cells were surgically implanted into the left and right lobes of liver of 30 New Zealand white rabbits, which were divided into 3 groups at random. Emulsion of lipiodol mixed with mitomydn C, and 5-FU bletilla microspheres were injected into the hepatic artery respectively, and saline was used as control agent. MR imaging was performed with turbo-flash sequence 14 d after tumor implantation and 7 d after interventional therapy. The steepest slopes (SS) of the signal intensity versus time curves were created for quantitative analysis, 7.5% Chinese ink gelatin solution was injected through ascending artery (17 cases) or portal vein(2 cases) for lesion microvessel area (MVA) measurement after the last MRI examination.The correlation between perfusion imaging and MVA was studied blindly.RESULTS: The SS values at the rim of tumor in lipiodol group (mean, 49% per second) and bletilla group (mean,35% per second) were significantly decreased (P<0.05) as compared with control group (mean, 124% per second), no difference was found between lipiodol and bletilla groups(P>0.05). In lipiodol group, the MVAs (24 974±11 836μm^2) in the center of the tumor were significantly smaller than those of the control group (35 510±15 675 μm^2) (P<0.05),while the MVAs (80 031±22 745 μm^2) around the tumor were significantly increased because small and dense plexuses appeared around the tumor which correlated to intense reaction of granulation tissue. None of the vessels was seen in the tumor in bletilla group, the peripheral MVAs of the tumor were significantly smaller than those of the control group (P<0.05) and lipiodol group (P<0.05). There was a good correlation between SS and MVAs in control group (rsl, 0.985, P<0.0001) and bletilla group (rsl, 0.743,P<0.05), the correlation was not significant in lipiodol group(rsl, 0.527, P>0.05).CONCLUSION: TACE with bletilla microspheres may enhance its anti-tumor effect by inhibiting the angiogenesis,and FP-MRI provides useful information to assess the TACE effect by depicting tumor vascularization and perfusion,

Antitumor effect of Gefitinib, an epidermal growth factor receptor tyrosine kinase inhibitor, combined with cytotoxic agent on murine hepatocellular carcinoma

AIM: To investigate the inhibitory effect of gefitinib combined with cytotoxic agent cisplatin (CDDP) on hepatocellular carcinoma (HCC). METHODS: Female Kunming mice and H22 hepatocarcinoma cells were used. Gefitinib at daily dose of 100 mg/kg body weight (BW) or lecithin liquid was given by gastrogavage once a day for 5 or 10 successive days. CDDP or normal saline (NS) was administered intraperitoneally (i.p.) once a day for 5 successive days. Mice were randomly divided into control group (lecithin, or NS, i.p.), CDDP group (daily dose, 1.2 mg/kg BW; d1-5, or d6-10), Gefitinib (d1-5, or d6-10, or d1-10), and Gefitinib combined with CDDP groups. The inhibitory rate (IR) of tumor, net BW, spleen index (SI), thymus index (TI) and the amount of peripheral blood cells of mice were detected on the 12th experiment day. RESULTS: The growth of HCC in mice was inhibited by Gefitinib alone (IR: 41% in d1-10 group and 30% in d1-5 group, respectively) or CDDP alone (IR: 32-54% in d1-5 group or d6-10 group). The highest inhibitory effect (IR: 56%) on HCC growth was observed in Gefitinib (d1-10) combined with CDDP (d1-5) group. Higher inhibition was also observed in CDDP (d1-5) followed by Gefitinib (d6-10) group than that in Gefitinib (d1-5) followed by CDDP (d6-10) group (IR: 61% vs 36%, P<0.01) in the independent study. Net BW, SI, TI and the amount of blood cells of mice in Gefitinib alone group were not significantly different from those in control groups. CONCLUSION: Gefitinib can significantly inhibit the growth of murine H22 hepatocellular carcinoma. If Gefitinib is used after CDDP treatment in animal experiments, the inhibitory effect could be enhanced.

Immune tolerance in pancreatic islet xenotransplantation

AIM: To observe the effect of tail vein injection with donor hepatocytes and/or splenoo/tes on the islet xenotransplantation rejection.METHODS: New-born male pigs and BALB/C mice were selected as donors and recipients respectively. Islet xenotransplantation was performed in recipients just after the third time of tail vein injection with donor hepatocytes and/or splenocytes.Macrophage phagocytosis, NK(natural killing cell) killing activity, T lymphocyte transforming function of spleen cells,antibody forming function of B lymphocytes, and T lymphocyte subsets were taken to monitor transplantation rejection. The effects of this kind of transplantation were indicated as variation of blood glucose and survival days of recipients.RESULTS: The results showed that streptozotocin (STZ) could induce diabetes mellitus models of mice. The preinjection of donor hepatocytes, splenocytes or their mixture by tail vein injection was effective in preventing donor islet transplantation from rejection, which was demonstrated by the above-mentioned immunological marks. Each group of transplantation could decrease blood glucose in recipients and increase survival days. Pre-injection of mixture of donor hepatocytes and splenocytes was more effective in preventing rejection as compared with that of donor hepatocyte or splenocyte pre-injection respectively.CONCLUSION: Pre-injection of donor hepatocytes, splenocytes or their mixture before donor islet transplantation is a good way in preventing rejection.

Construction of a metastasis-associated gene subtracted cDNA library of human colorectal carcinoma by suppression subtraction hybridization

AIM: To construct a differentially-expressed gene subtracted cDNA library from two colorectal carcinoma (CRC) cell lines with different metastatic phenotypes by suppression subtractive hybridization.METHODS: Two cell lines of human CRC from the same patient were used. SW620 cell line showing highly metastatic potential was regarded as tester in the forward subtractive hybridization, while SW480 cell line with lowly metastatic potential was treated as tester in the reverse hybridization. Suppression subtractive hybridization (SSH) was employed to obtain cDNA fragments of differentially expressed genes for the metastasis of CRC. These fragments were ligated with T vectors, screened through the blue-white screening system to establish cDNA library.RESULTS: After the blue-white screening, 235 white clones were picked out from the positive-going hybridization and 232 from the reverse. PCR results showed that 200-700 bp inserts were seen in 98% and 91% clones from the forward and reverse hybridizations, respectively.CONCLUSIONS: A subtractive cDNA library of differentially expressed genes specific for metastasis of CRC can be constructed with SSH and T/A cloning techniques.

Overexpression of ETS2 in human esophageal squamous cell carcinoma

AIM: To study the expression pattern of ETS2 (erythroblastosisvirus oncogene homolog 2) in human esophageal squamouscell carcinoma (ESCC).METHODS: Reverse transcription polymerase chain reaction(RT-PCR) and Northern blot were performed to examinethe expression level of ETS2 mRNA in 37 pairs of ESCCtissue samples. Western blot and immunohistochemistrywere carried out to check the expression level of ETS2 proteinin 30 pairs of ESCC tissue specimens.RESULTS: RT-PCR and Northern blot analysis showed thatETS2 mRNA upregulated in 75.7 % (28/37) examined ESCCtissues relative to matched normal tissues. From those 37cases, 14 cases were randomly selected to perform Westernblot and the results revealed that ETS2 protein overexpressedin 71.4 % (10/14) checked ESCC tissues compared with thecorresponding normal tissues. Moreover, the expressionpatterns of ETS2 protein in those 14 cases were identical tothose of ETS2 mRNA displayed by RT-PCR or Northern Blot.Immunohistochemistry analysis showed that the expressionlevel of ETS2 protein rose in 75 % (12/16) tumor epithelialcells contrasted to the normal cells. Altogether the expressionlevel of ETS2 protein increased in 73.3 % (22/30) checkedESCC tissue samples contrary to their normal counterparts.CONCLUSION: The results suggested that ETS2overexpressed in paired human ESCC tissue samples at bothmRNA and protein levels and may be associated with thetumorigenesis of esophagus.

Molecular Simulation of Hydrogen Adsorption Density in Single-Walled Carbon Nanotubes and Multilayer Adsorption Mechanism

The adsorption of hydrogen onto single-walled carbon nanotubes (SWCNTs) was studied by molecular dynamics (MD) sim'lation. It was found that the hydrogen molecules distribute regularly inside and outside of the tube. Density distribution was computed for H2 molecule. Theoretical analysis of the result showed the multilayer adsorption mechanism of SWCNTs. The storage of H2 in SWCNTs is computed, which provides essential theoretical reference for further study of hydrogen adsorption in SWCNTs.

Friction and Wear Characteristics of Brush Plating Ni/nano-Al2O3 Composite Coating under Sand-Containing Oil

Ni-matrix composite coating containing AI2O3 nano-particles is prepared by brush plating. The effects of the nano-particles on the microstructure, microhardness and tribological properties of the composite coating under the lubrication of a diesel oil containing sand are investigated. The results show that the microstructure of the composite coating is finer than that of the pure nickel coating due to the codeposition of the nano-particles. When the nano-particle concentration in the electroplating bath reaches 20 g/L, the microhardness, and wear resistance of the composite coating is as much as 1.6 times and 1.3-2.5 times of those of the pure nickel coating respectively. The main hardening mechanism of the composite coating is superfine crystal grain strengthening and dispersion strengthening. The composite coating is characterized by scuffing as it slides against Si3N4 under the present test conditions.

Development and application of automated vicarious calibration system

In order to improve the frequency and precision of radiometric calibration, the automated vicarious calibration system（AVCS） is developed and deployed at the Dunhuang test site to perform vicarious calibration without the in situ manned measurements. The surface and atmospheric parameters are automatically collected by AVCS.An absolute radiometric calibration approach based on AVCS is proposed. Six successful calibrations of the Aqua Moderate Resolution Imaging Spectroradiometer（MODIS） are conducted. The results are in good agreement with the on-board calibration system with all the relative differences less than 4%. It enables us to monitor the change of a sensor over long time scales.