去铁胺单独及联合三氧化二砷对裸鼠HL-60细胞移植瘤的抑制作用及其可能机制

目的 探讨去铁胺(DFO)单独及联合三氧化二砷(As2O3)对裸鼠HL-60白血病细胞移植瘤的抑制作用及机制,为临床采用铁螯合剂治疗或辅助治疗白血病提供实验依据.方法 用高致瘤性HL-60细胞建立裸鼠皮下移植瘤模型,随机分为4组:50 mg/kg DFO单药组、3 mg/kg As2O3单药组、联合用药组(50 mg/...     

Virus inactivation of plasma-derived proteins by pasteurization in the presence of guanidine hydrochloride

BACKGROUND: Viruses, among them parvovirus B19 and other small, nonenveloped viruses, may be present in human blood and may contaminate plasma-derived therapeutics. Efficient inactivation or removal of such viruses, especially parvoviruses, represents a current problem and corresponding technologies are under investigation. In this report, such a technology is described. STUDY DESIGN AND METHODS: A recently developed pasteurization of human apolipoprotein A-I (apoA-I), which is performed at 60 degrees C for 10 hours in the presence of guanidine hydrochloride (GdnHCl), was validated by using a series of model viruses, including members of the families parvoviridae and picornaviridae. The model viruses were spiked into the apoA-I- and GdnHCl-containing solutions, and virus inactivation was evaluated by infectivity assays in cell cultures. The mechanism of virus inactivation was studied by virus sedimentation analysis using the picornavirus model. RESULTS: All viruses tested were inactivated to levels below the limit of detection, although different inactivation kinetics were obtained for the different viruses. The mechanism of virus inactivation by this pasteurization was disassembly of the virus particles into single proteins or small noninfectious viral subunits. CONCLUSION: The pasteurization validated in this report has the potential to inactivate a wide range of transfusion-relevant viruses including parvoviruses and picornaviruses.     

2型糖尿病小鼠小脑代谢物的~1H NMR研究

目的:通过离体的高分辨核磁共振氢谱(1H NMR)技术研究2型糖尿病db/db小鼠小脑的代谢变化。方法:采用8只15周龄2型糖尿病模型db/db小鼠为实验组,11只15周龄野生正常小鼠为对照组,对其小脑组织进行离体的1H NMR检测分析。结果:实验组与对照组相比小脑的代谢模式明显不同,甘氨酸(Gly)、天冬氨酸(Asp)、谷氨酸(Glu)、γ-氨基丁酸(GABA)、N-乙酰天门冬氨酸(NAA)、丙氨酸(Ala)等代谢物浓度明显下降,差异有统计学意义(P<0.05或P<0.01);谷氨酰胺(Gln)、牛磺酸(Tau)、乳酸(Lac)等代谢物水平显著上升,差异有统计学意义(P<0.05或P<0.01)。结论:代谢组学结果说明2型糖尿病模型db/db小鼠小脑中糖代谢、氨基酸代谢出现了紊乱,这为进一步认识糖尿病脑病的发病机制提供了线索。     

脊髓损伤后早期小鼠肠道功能的变化

目的探讨脊髓损伤后短期内小鼠肠道功能的变化。方法将105只昆明种小鼠随机分为正常组(A组,n=30)、假手术组(B组,n=30)和模型组(C组,n=45)。A组不作处理,B组仅暴露脊髓,不夹持。C组采用动脉瘤夹夹持T10处脊髓,复制脊髓损伤模型。分别于术后12 h、24 h、48 h测定小鼠回肠肌电慢波及平滑肌收缩力,并做回肠HE染色。结果脊髓损伤后12 h、24h、48 h,C组小鼠肌电频率和振幅低于A组和B组(P0.05),收缩力振幅低于A组和B组(P0.05),但24 h、48 h后收缩力频率高于A组和B组(P0.05)。C组各时间点肠黏膜评分均较A组和B组高(P0.05)。结论小鼠脊髓损伤后早期,肠道平滑肌肌电活动减弱,收缩力减小,肠黏膜轻度损伤。     

Low-dose streptozotocin-induced autoimmune diabetes is under the genetic control of the major histocompatibility complex in mice

Summary In mice, an experimental autoimmune diabetes can be induced by multiple injections with low doses of streptozotocin. Since different mouse strains show a varying susceptibility towards this treatment, we have examined whether the experimental autoimmune diabetes is under the genetic control of the major histocompatibility complex (H-2 complex). Mice of five congenic resistant strains, differing in their genome only at the H-2 region, were identically treated on five consecutive days with 40 mg streptozotocin/kg body weight. Genes at the H-2 complex were found to determine the susceptibility towards the diabetogenic effect of streptozotocin: mice of H-2 haplotype k (B10.BR) developed persistent and strong hyperglycaemia (blood glucose approximately 17 mmol/1), mice of strain B10.A (H-2^a), C57BL/10 (H-2^b) and B10.D2 (H-2^d) reacted with moderate hyperglycaemia (between 11.5 and 15.5 mmol/1), whereas mice of strain B10.S (H-2^s) were resistant to the diabetogenic effect of low-dose streptozotocin except for a small and transient rise of blood glucose levels. It is concluded that genes within the major histocompatibility complex affect the diabetogenic response to multiple low-dose streptozotocin treatment.     

Inhibition of Shp2 suppresses mutant EGFR-induced lung tumors in transgenic mouse model of lung adenocarcinoma

Epidermal growth factor receptor (EGFR) mutants drive lung tumorigenesis and are targeted for therapy. However, resistance to EGFR inhibitors has been observed, in which the mutant EGFR remains active. Thus, it is important to uncover mediators of EGFR mutant-driven lung tumors to develop new treatment strategies. The protein tyrosine phosphatase (PTP) Shp2 mediates EGF signaling. Nevertheless, it is unclear if Shp2 is activated by oncogenic EGFR mutants in lung carcinoma or if inhibiting the Shp2 PTP activity can suppress EGFR mutant-induced lung adenocarcinoma. Here, we generated transgenic mice containing a doxycycline (Dox)-inducible PTP-defective Shp2 mutant (tetO-Shp2CSDA). Using the rat Clara cell secretory protein (CCSP)-rtTA-directed transgene expression in the type II lung pneumocytes of transgenic mice, we found that the Gab1-Shp2 pathway was activated by EGFR^L858R in the lungs of transgenic mice. Consistently, the Gab1-Shp2 pathway was activated in human lung adenocarcinoma cells containing mutant EGFR. Importantly, Shp2CSDA inhibited EGFR^L858R-induced lung adenocarcinoma in transgenic animals. Analysis of lung tissues showed that Shp2CSDA suppressed Gab1 tyrosine phosphorylation and Gab1-Shp2 association, suggesting that Shp2 modulates a positive feedback loop to regulate its own activity. These results show that inhibition of the Shp2 PTP activity impairs mutant EGFR signaling and suppresses EGFR^L858R-driven lung adenocarcinoma.     

Adjuvant treatment with tumor-targeting Salmonella typhimurium A1-R reduces recurrence and increases survival after liver metastasis resection in an orthotopic nude mouse model

Colon cancer liver metastasis is often the lethal aspect of this disease. Well-isolated metastases are candidates for surgical resection, but recurrence is common. Better adjuvant treatment is therefore needed to reduce or prevent recurrence. In the present study, HT-29 human colon cancer cells expressing red fluorescent protein (RFP) were used to establish liver metastases in nude mice. Mice with a single liver metastasis were randomized into bright-light surgery (BLS) or the combination of BLS and adjuvant treatment with tumor-targeting S. typhimurium A1-R. Residual tumor fluorescence after BLS was clearly visualized at high magnification by fluorescence imaging. Adjuvant treatment with S. typhimurium A1-R was highly effective to increase survival and disease-free survival after BLS of liver metastasis. The results suggest the future clinical potential of adjuvant S. typhimurium A1-R treatment after liver metastasis resection.     

Role of promyelocytic leukemia (PML) protein in tumor suppression

The promyelocytic leukemia (PML) gene encodes a putative tumor suppressor gene involved in the control of apoptosis, which is fused to the retinoic acid receptor alpha (RARalpha) gene in the vast majority of acute promyelocytic leukemia (APL) patients as a consequence of chromosomal translocations. The PMLRARalpha oncoprotein is thought to antagonize the function of PML through its ability to heterodimerize with and delocalize PML from the nuclear body. In APL, this may be facilitated by the reduction to heterozygosity of the normal PML allele. To determine whether PML acts as a tumor suppressor in vivo and what the consequences of deregulated programmed cell death in leukemia and epithelial cancer pathogenesis are, we crossed PML(-/-) mice with human cathepsin G (hCG)-PMLRARalpha or mammary tumor virus (MMTV)/neu transgenic mice (TM), models of leukemia and breast cancer, respectively. The progressive reduction of the dose of PML resulted in a dramatic increase in the incidence of leukemia, and in an acceleration of leukemia onset in PMLRARalpha TM. By contrast, PML inactivation did not affect neu-induced tumorigenesis. In hemopoietic cells from PMLRARalpha TM, PML inactivation resulted in impaired response to differentiating agents such as RA and vitamin D3 as well as in a marked survival advantage upon proapoptotic stimuli. These results demonstrate that: (a) PML acts in vivo as a tumor suppressor by rendering the cells resistant to proapoptotic and differentiating stimuli; (b) PML haploinsufficiency and the functional impairment of PML by PMLRARalpha are critical events in APL pathogenesis; and (c) aberrant control of programmed cell death plays a differential role in solid tumor and leukemia pathogenesis.