三种含钙矿物抑制剂研究进展及机理

白钨矿与萤石、方解石等含钙矿物表面性质相似,可浮性相近,在浮选体系中难以实现白钨矿与它们的高效分离和有效回收,因此在研究白钨选矿浮选捕收剂的同时,开展对含钙脉石矿物高效分离抑制剂的研究至关重要。文章综述了近年来白钨矿与含钙脉石矿物分离抑制剂的研究现状,详细阐述了多种无机抑制剂和有机抑制剂的抑制机理和应用,并结合当前白钨矿与含钙矿物抑制剂的研究进展,认为开发对含钙矿物具有高效抑制性能的药剂引入特性基团增强抑制剂的亲水性,能达到提高其选择性的目的,最后探讨了抑制剂研究的新方向。

可溶性环氧化物水解酶脲类抑制剂的研究进展

可溶性环氧化物水解酶(Soluble epoxide hydrolases,sEH)是一种能代谢环氧脂肪酸的酶,它在哺乳动物中广泛存在,能将内源性环氧二十碳三烯酸(Epoxyeicosatrienoic acids or EETs)转化为二羟基二十碳三烯酸(Dihydroxy epoxyeicosatrienoic acids or DHETs)。内源性EETs是由花生四烯酸(Arachidonic acid or AA)经细胞色素P450氧化而来,它是生物体内重要的信号分子,具有调节离子转运和基因表达、血管扩张、抗炎等作用。在动物体内,有很多种途径可以降解EETs,其中sEH将EETs代谢为DHETs是最主要的代谢途径,使EETs的浓度降低,生理活性下降,从而使体内的血压升高,并进一步影响肾脏,心脏等功能。研究表明,抑制sEH的活性可治疗多种心血管疾病及炎症。因此开发新型sEH的抑制剂在治疗相关疾病中具有很好的应用价值。主要概述了sEH的抑制剂的作用机理以及抑制剂研究的最新进展,并展望了抑制剂今后的研究方向。

SIRT1机理型抑制剂的合成及活性评价

目的:基于SIRT1机理型抑制剂-硫代乙酰赖氨酸化合物,通过优化硫代酰化基团,以发现更优秀的SIRT1抑制剂。方法:基于类似的合成途径,合成了3个具有不同硫代酰化基团化合物,并通过体外及细胞内实验,评估了它们对SIRT1的抑制活性。结果与结论:发现2个改进的SIRT1小分子抑制剂,化合物3和4具有更优秀的SIRT1抑制剂活性。进一步研究表明,化合物3具有更优秀的抗肿瘤活性。

Anti-cancer effect of iNOS inhibitor and its correlation with angiogenesis in gastric cancer

AIM: To observe the anti-cancer effect of iNOS selective inhibitor (aminoguanidine, AG) and investigate the relationship between iNOS inhibitor and angiogenesis, infiltration or metastasis in MFC gastric cancer xenografts.METHODS: Fifty athymic mice xenograft models were established by inoculating gastric cancer cell MFC subcutaneously. Twenty-four hours later, 0.9% sodium chloride solution, mitomycin, low dosage AG, high dosage AG, mitomycin and AG were administered by intraperitoneal injection respectively. Thus these mice were divided into five groups of 10 each randomly: control group, MMC group,AGL group, AGH group, MMC+AGH group. Two weeks later the mice were killed, and the tumor weight, inhibitory rate were evaluated. Greiss assay was used to detect the nitric oxide levels in plasma. HE and immunohistochemistry staining were used to examine microvessel density (MVD)and the expression of iNOS, VEGF, and PCNA. Apoptosis was detected by using TUNEL assay.RESULTS: The inhibitory rates in MMC+AGH group and AGH group were 52.9% and 47.1% respectively, which is significant statistically compared with that of control group (0). In treatment groups, the cell proliferation index (PI)was lower and apoptosis index was higher than those of control group. Microvessel density, iNOS, and VEGF in MMC+ AGH group were 8.8±2.6, 2.4±1.1, and 2.1±1.4respectively, which is significant statistically compared with those of control group (68.3±10.6, 11.3±1.3, and 10.3±1.6). The NO level in plasma of MMC+ AGH and AGH group were 12.7±2.1 and 12.9±2.0 μmol/L. Compared with that of control group (46.6±2.3 μmol/L), the difference is statistically significant.CONCLUSION: AG has anticancer effect on gastric cancer,and it has positive synergistic effect with chemotherapeutic drugs. It may play important inhibitory roles in angiogenesis of gastric cancer. The anticancer effect of iNOS inhibitors may include inducing cell apoptosis, suppressing cell proliferation and reducing angiogenesis.

Conversion to sirolimus immunosuppression in liver transplantation recipients with hepatocellular carcinoma:Report of an initial experience

AIM： To report a retrospective analysis of preliminary results of 36 patients who received sirolimus （SRL, Rapamune, rapamycin） in a consecutive cohort of 248 liver allograft recipients. METHODS： Thirty-six liver transplant patients with hepatocellular carcinoma （HCC） who were switched to SRL- based immunosuppression therapy from tacrolimus were enrolled in this study. The patients who were diagnosed as advanced HCC before orthotopic liver transplantation （OLT） were divided into group A （n = 11）, those who were found to have HCC recurrence and/or metastasis after OLT were assigned to group B （n = 18）, and those who developed renal insuffidency caused by caldneurin inhibitor （CNI） were assigned to group C （n = 7） after OLT. RESULTS： The patients were followed up for a median of 10.4 mo （range, 3.8-19.1 mo） after conversion to SRL therapy and 12.3 mo （range, 5.1-34.4 too） after OLT. Three patients developed mild acute cellular rejection 2 wk after initiating SRL therapy, which was fully reversed after prednisolone pulse therapy. In group A, only 1 patient was found to have HCC recurrence and metastasis 12 mo after OLT. In group B, 66.7% （12/18） patients （2 with progressive tumor, 7 with stable tumor and 3 without tumor） were still alive due to conversing to SRL and/ or resection for HCC recurrence at the end of a median follow-up of 6.8 mo post conversion and 10.7 mo posttransplant. In group C, no HCC recurrence was demonstrated in 7 patients, and renal function became normal after SRL therapy. Thrombocytopenia （n = 2）, anemia （n = 8）, and oral aphthous ulcers （n = 7） found in our cohort were easily manageable. CONCLUSION： The conversion to SRL-based immunosuppression may inhibit the recurrence and metastasis of HCC and improve CNI-induced renal insufficiency in OLT patients with HCC.

Control of zinc corrosion in acidic media: Green fenugreek inhibitor

Fenugreek seeds extract was examined as a green corrosion inhibitor for Zn in 2.0 mol/L H2SO4 and 2.0 mol/L HClsolutions by mass loss and electrochemical measurements. Scanning electron microscope （SEM） images show that the surfacedamage is decreased in the presence of the inhibitor. X-rays photoelectron spectroscopy （XPS） analysis was performed to identify thecorrosion product, ZnO, and to prove the inhibitor adsorption mechanism. The maximum inhibition efficiency values are 90.7% after1 h and 66.6% after 0.5 h by 200 mL/L of fenugreek extract in H2SO4 and HCl solutions, respectively. Addition of I^- ion greatlyimproves the inhibition efficiency of fenugreek seeds extract for Zn corrosion in HCl due to the synergistic effect. Potentiodynamicpolarization and EIS measurements prove the inhibition ability of fenugreek for Zn corrosion in HCl as indicated by the decreasedcorrosion current density and increased charge transfer resistance values in the presence of fenugreek.

Epigenetics of proteasome inhibition in the liver of rats fed ethanol chronically

AIM： TO examine the effects of ethanol-induced proteasome inhibition, and the effects of proteasome inhibition in the regulation of epigenetic mechanisms.METHODS： Rats were fed ethanol for 1 mo using the Tsukamoto-French model and were compared to rats given the proteasome inhibitor PS-341 （Bortezomib, Velcade^TM） by intraperitoneal injection. Microarray analysis and real time PCR were performed and proteasome activity assays and Western blot analysis were performed using isolated nuclei.RESULTS： Chronic ethanol feeding caused a significant inhibition of the ubiquitin proteasome pathway in the nucleus, which led to changes in the turnover of transcriptional factors, histone-modifying enzymes, and, therefore, affected epigenetic mechanisms. Chronic ethanol feeding was related to an increase in histone acetylation, and it is hypothesized that the proteasome proteolytic activity regulated histone modifications by controlling the stability of histone modifying enzymes, and, therefore, regulated the chromatin structure, allowing easy access to chromatin by RNA polymerase, and, thus, proper gene expression. Proteasome inhibition by PS-341 increased histone acetylation similar to chronic ethanol feeding. In addition, proteasome inhibition caused dramatic changes in hepatic remethylation reactions as there was a significant decrease in the enzymes responsible for the regeneration of S-adenosylmethionine, and, in particular, a significant decrease in the betaine-homocysteine methyltransferase enzyme. This suggested that hypomethylation was associated with proteasome inhibition, as indicated by the decrease in histone methylation.CONCLUSION： The role of proteasome inhibition in regulating epigenetic mechanisms, and its link to liver injury in alcoholic liver disease, is thus a promising approach to study liver injury due to chronic ethanol consumption.

Pathogenesis of NSAID-induced gastric damage:Importance of cyclooxygenase inhibition and gastric hypermotility

This article reviews the pathogenic mechanism of nonsteroidal anti-inflammatory drug(NSAID)-induced gastric damage,focusing on the relation between cyclooxygenase(COX) inhibition and various functional events.NSAIDs,such as indomethacin,at a dose that inhibits prostaglandin(PG) production,enhance gastric motility,resulting in an increase in mucosal permeability,neutrophil infiltration and oxyradical production,and eventually producing gastric lesions.These lesions are prevented by pretreatment with PGE 2 and antisecretory drugs,and also via an atropine-sensitive mechanism,not related to antisecretory action.Although neither rofecoxib(a selective COX-2 inhibitor) nor SC-560(a selective COX-1 inhibitor) alone damages the stomach,the combined administration of these drugs provokes gastric lesions.SC-560,but not rofecoxib,decreases prostaglandin E 2(PGE 2) production and causes gastric hypermotility and an increase in mucosal permeability.COX-2 mRNA is expressed in the stomach after administration of indomethacin and SC-560 but not rofecoxib.The up-regulation of indomethacin-induced COX-2 expression is prevented by atropine at a dose that inhibits gastric hypermotility.In addition,selective COX-2 inhibitors have deleterious influences on the stomach when COX-2 is overexpressed under various conditions,including adrenalectomy,arthritis,and Helicobacter pylori-infection.In summary,gastric hypermotility plays a primary role in the pathogenesis of NSAID-induced gastric damage,and the response,causally related with PG deficiency due to COX-1 inhibition,occurs prior to other pathogenic events such as increased mucosal permeability;and the ulcerogenic properties of NSAIDs require the inhibition of both COX-1 and COX-2,the inhibition of COX-1 upregulates COX-2 expression in association with gastric hypermotility,and PGs produced by COX-2 counteract the deleterious effect of COX-1 inhibition.