耐万古霉素微生物筛选模型

为获得耐万古霉素的肠球菌和金葡球菌，利用紫外线对Enterococcus faecalis458和Staphylococcus aureus9918进行诱变，确定在不同处理中以紫外线照射30s为最佳。最后获得对万古霉素中敏的E．faecalis458 V20和S．aureus9918 V16，药物敏感性试验表明前者对青霉素G钾和红霉素耐药，而后者对青霉素G钾、红霉素、苯唑青霉素钠和氨苄青霉素钠耐药。两者对万古霉素的耐药性在无药培养基上传10代后略微下降。     

D-peptide inhibitors of the p53–MDM2 interaction for targeted molecular therapy of malignant neoplasms

The oncoproteins MDM2 and MDMX negatively regulate the activity and stability of the tumor suppressor protein p53, conferring tumor development and survival. Antagonists targeting the p53-binding domains of MDM2 and MDMX kill tumor cells both in vitro and in vivo by reactivating the p53 pathway, promising a class of antitumor agents for cancer therapy. Aided by native chemical ligation and mirror image phage display, we recently identified a D-peptide inhibitor of the p53-MDM2 interaction termed ^DPMI-α (TNWYANLEKLLR) that competes with p53 for MDM2 binding at an affinity of 219 nM. Increased selection stringency resulted in a distinct D-peptide inhibitor termed ^DPMI-γ (DWWPLAFEALLR) that binds MDM2 at an affinity of 53 nM. Structural studies coupled with mutational analysis verified the mode of action of these D-peptides as MDM2-dependent p53 activators. Despite being resistant to proteolysis, both ^DPMI-α and ^DPMI-γ failed to actively traverse the cell membrane and, when conjugated to a cationic cell-penetrating peptide, were indiscriminately cytotoxic independently of p53 status. When encapsulated in liposomes decorated with an integrin-targeting cyclic-RGD peptide, however, ^DPMI-α exerted potent p53-dependent growth inhibitory activity against human glioblastoma in cell cultures and nude mouse xenograft models. Our findings validate D-peptide antagonists of MDM2 as a class of p53 activators for targeted molecular therapy of malignant neoplasms harboring WT p53 and elevated levels of MDM2.     

地塞米松在大鼠创伤性休克中的作用

本实验选用Ｗｉｓｔａｒ大鼠，复制创作性休克的动物模型，观察致伤体体内脂质过氧化物含量和纤维结合蛋白水平的变化以及地塞米松对创伤性休克的治疗作用。结果显示，大鼠致伤后１２０ｍｉｎ血浆ＭＤＡ含量即明显增加，而血浆纤维结合蛋白水平则明显降低；若使用地塞米治疗，可使致伤后的血流动力学大为改善。     

Anti-tumor and apoptotic effects in vitro and in vivo of a traditional Chinese medicine prescription

Background  Zhongfei Mixture (ZM), a traditional Chinese medicine, exploited from the clinical experience, has mainly been used for the treatment of advanced lung cancer since it was produced in 1983. However, little research has been conducted on its anti-tumor mechanism. In this study, we aimed to investigate the anti-tumor and apoptotic effects of ZM in vitro and in vivo.

Methods  The growth inhibition effect of ZM on A549 cells was evaluated by MTT assay. Morphological observation and clone forming tests were performed to determine the effect of ZM on cell viability. Cell cycle distribution and apoptosis were analyzed by flow cytometry. In addition, the in vivo anti-proliferation activity of ZM was evaluated using mice bearing Lewis lung carcinoma. Further, the apoptosis of cells in tumor tissue was determined by the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assay, and the expression of Ki-67 protein in tumor tissues was analyzed by En-Vision immuno-histochemistry staining.

Results  ZM exerted an obvious inhibitory effect on proliferation of A549 cells. It arrested A549 cells in G₂-M phase and induced apoptosis. Compared with 3.02% and 5.32% in control group, the percentages of cells arrested in G₂-M phase were 19.20% and 19.58% in 7.94 mg/ml ZM treated A549 cells at 24 hours and 48 hours. Moreover, the apoptosis rate increased from 0.18% to 18.01% after ZM treatment for 48 hours. ZM also significantly inhibited tumor growth in the tumor-implanted mice. Compared with saline control group, the effects of ZM showed significant tumor growth inhibition (P <0.05). Furthermore, ZM could down-regulate the expression of Ki-67 in tumor tissue in mice bearing Lewis lung carcinoma.

Conclusions  Our results indicated that ZM has notable anti-tumor effect and the effects of ZM in moderate dose groups were superlative both in vitro and in vivo. The possible mechanism of ZM might be associated with arresting cell cycle in G₂-M phase as well as down-regulating Ki-67 expression in tumor tissues.

     

Comparative study of pulmonary responses to nano- and submicron-sized ferric oxide in rats

Ferric oxide (Fe(2)O(3)) nanoparticles are of considerable interest for application in nanotechnology related fields. However, as iron being a highly redox-active transition metal, the safety of iron nanomaterials need to be further studied. In this study, the size, dose and time dependent of Fe(2)O(3) nanoparticle on pulmonary and coagulation system have been studied after intratracheal instillation. The Fe(2)O(3) nanoparticles with mean diameters of 22 and 280 nm, respectively, were intratracheally instilled to male Sprague Dawley rats at low (0.8 mg/kgbw) and high (20 mg/kgbw) doses. The toxic effects were monitored in the post-instilled 1, 7 and 30 days. Our results showed that the Fe(2)O(3) nanoparticle exposure could induce oxidative stress in lung. Alveolar macrophage (AM) over-loading of phagocytosed nanoparticle by high dose treatment had occurred, while the non-phagocytosed particles were found entering into alveolar epithelial in day 1 after exposure. Several inflammatory reactions including inflammatory and immune cells increase, clinical pathological changes: follicular hyperplasia, protein effusion, pulmonary capillary vessel hyperaemia and alveolar lipoproteinosis in lung were observed. The sustain burden of particles in AM and epithelium cells has caused lung emphysema and pro-sign of lung fibrosis. At the post-instilled day 30, the typical coagulation parameters, prothrombin time (PT) and activated partial thromboplastin time (APTT) in blood of low dose 22 nm-Fe(2)O(3) treated rats were significantly longer than the controls. We concluded that both of the two-sized Fe(2)O(3) particle intratracheal exposure could induce lung injury. Comparing with the submicron-sized Fe(2)O(3) particle, the nano-sized Fe(2)O(3) particle may increase microvascular permeability and cell lysis in lung epitheliums and disturb blood coagulation parameters significantly.     

Recent advances in lymphatic targeted drug delivery system for tumor metastasis

The lymphatic system has an important defensive role in the human body. The metastasis of most tumors initially spreads through the surrounding lymphatic tissue and eventually forms lymphatic metastatic tumors; the tumor cells may even transfer to other organs to form other types of tumors. Clinically, lymphatic metastatic tumors develop rapidly. Given the limitations of surgical resection and the low effectiveness of radiotherapy and chemotherapy, the treatment of lymphatic metastatic tumors remains a great challenge. Lymph node metastasis may lead to the further spread of tumors and may be predictive of the endpoint event. Under these circumstances, novel and effective lymphatic targeted drug delivery systems have been explored to improve the specificity of anticancer drugs to tumor cells in lymph nodes. In this review, we summarize the principles of lymphatic targeted drug delivery and discuss recent advances in the development of lymphatic targeted carriers.     

Acute toxicity of nano- and micro-scale zinc powder in healthy adult mice

The purpose of this study is to evaluate the acute toxicity of oral exposure to nanoscale zinc powder in mice. The healthy adult male and female mice were gastro-intestinally administered at a dose of 5 g/kg body weight with two size particles, nanoscale zinc (N-Zn) and microscale zinc (M-Zn) powder, while one group mice treated with sodium carboxy methyl cellulose was used as the control. The symptoms and mortality after zinc powder treatment were recorded. The effects of particles on the blood-element, the serum biochemical level and the blood coagulation were studied after 2 weeks of administration. The organs were collected for histopathological examination. The N-Zn treated mice showed more severe symptoms of lethargy, vomiting and diarrhea in the beginning days than the M-Zn mice. Deaths of two mice occurred in the N-Zn group after the first week of treatment. The mortalities were confirmed by intestinal obstruction of the nanoscale zinc aggregation. The biochemical liver function tests of serum showed significantly elevated ALT, AST, ALP, and LDH in the M-Zn mice and ALT, ALP, and LDH in the N-Zn mice compared with the controls (P<0.05), which indicated that the liver damage was probably induced by both micro- and nano-scale zinc powders. The clinical changes were observed in the two treated group mice as well. The levels of the above enzymes were generally higher in the M-Zn mice than in the N-Zn mice, which implied that M-Zn powder could induce more severe liver damage than N-Zn. The biochemical renal function tests of serum BUN and CR in the M-Zn mice markedly increased either compared with the N-Zn mice or with the controls (P<0.05), but no significant difference was found between the N-Zn and the control mice. However, severe renal lesions were found by the renal histopathological examination in the N-Zn exposed mice. Therefore, we concluded that severe renal damage could occur in the N-Zn treated mice, though no significant change of blood biochemical levels occurred. Blood-element test showed that in the N-Zn mice, PLT and RDW-CV significantly increased, and HGB and HCT significantly decreased compared to the controls, which indicated that N-Zn powder could cause severe anemia. Besides the pathological lesions in the liver, renal, and heart tissue, only slight stomach and intestinal inflammation was found in all the zinc treated mice, without significant pathological changes in other organs.