年龄相关性白内障晶状体上皮细胞中hTERT的活性表达

目的：探讨hTERT在年龄相关性白内障晶状体上皮细胞（lens epithelial cells,LEC）中的活性表达及在白内障形成中的作用。方法：对40例年龄相关性白内障患者和10例正常LEC中的hTERT进行原位杂交技术检测,并进行比较。结果：年龄相关性白内障LEC中hTERT的阳性表达率明显增高,与正常晶状体组相比,有显著性差异（P〈0.01）。结论：LEC中hTERT活性的变化与年龄相关性白内障的形成密切相关,随着年龄的增长,hTERT的表达活性升高,使LEC发生衰老,从而形成白内障。     

复明眼液对体外诱导的兔晶状体上皮细胞凋亡的影响

目的 探讨中药复明眼液对兔晶状体上皮细胞(1ens epithelial cells,LEC)凋亡的影响。方法 采用H2O2诱导体外培养的兔IEC，用SOD超微量快速测定和TBA荧光法分别检测不同浓度的复明眼液对兔LEC的超氧化物歧化酶(superoxide dismulase,SOD)活性和脂质过氧化物(lipid peroxide,LPO)含量的影响。结果 终浓度400μg/ml、800μg/ml复明眼液可明显降解兔LEC的LPO含量。结论 一定浓度的复明眼液具有提高兔LEC抗氧化作用的能力。保护兔LEC免受氧化损伤的作用，防止兔LEC发生凋亡。     

色素上皮衍生因子在人白内障房水及晶状体上皮细胞中的表达

目的 探讨色素上皮衍生因子(PEDF)在人白内障眼房水及晶状体上皮细胞(LEC)中的表达水平与年龄的关系.方法 收集老年性白内障130例和先天性白内障15例.超声乳化术中取房水,酶联免疫吸附法(ELISA)检测房水PEDF浓度;选上述先天性白内障和老年性白内障高龄者各15例,术中取前囊膜标本用蛋白质免疫印迹法(Western Blot)检测LEC的PEDF表达.结果 患眼房水PEDF平均浓度为(180.9±78.6)ng/ml,且与年龄均呈负相关(r=0.821,P＜0.001);患眼LEC中存在PEDF的蛋白表达,且幼龄组的表达水平远高于高龄组.结论 患眼LEC中存在PEDF活性,其房水及LEC中的PEDF水平均随年龄增加而显著下降,提示PEDF可能以旁分泌和自分泌的方式调节或(和)保护LEC.     

Central role of interferon-beta in thymic events leading to myasthenia gravis

The thymus plays a primary role in early-onset Myasthenia Gravis (MG) mediated by anti-acetylcholine receptor (AChR) antibodies. As we recently showed an inflammatory and anti-viral signature in MG thymuses, we investigated in detail the contribution of interferon (IFN)-I and IFN-III subtypes in thymic changes associated with MG. We showed that IFN-I and IFN-III subtypes, but especially IFN-β, induced specifically α-AChR expression in thymic epithelial cells (TECs). We also demonstrated that IFN-β increased TEC death and the uptake of TEC proteins by dendritic cells.In parallel, we showed that IFN-β increased the expression of the chemokines CXCL13 and CCL21 by TECs and lymphatic endothelial cells, respectively. These two chemokines are involved in germinal center (GC) development and overexpressed in MG thymus with follicular hyperplasia. We also demonstrated that the B-cell activating factor (BAFF), which favors autoreactive B-cells, was overexpressed by TECs in MG thymus and was also induced by IFN-β in TEC cultures.Some of IFN-β effects were down-regulated when cell cultures were treated with glucocorticoids, a treatment widely used in MG patients that decreases the number of thymic GCs.Similar changes were observed in vivo. The injections of Poly(I:C) to C57BL/6 mice triggered a thymic overexpression of IFN-β and IFN-α2 associated with increased expressions of CXCL13, CCL21, BAFF, and favored the recruitment of B cells. These changes were not observed in the thymus of IFN-I receptor KO mice injected with Poly(I:C), even if IFN-β and IFN-α2 were overexpressed.Altogether, these results demonstrate that IFN-β could play a central role in thymic events leading to MG by triggering the overexpression of α-AChR probably leading to thymic DC autosensitization, the abnormal recruitment of peripheral cells and GC formation.     

Possible involvement of c-myc but not ras genes in hepatocellular carcinomas developing after spontaneous hepatitis in LEC rats.

LEC (Long-Evans with a cinnamon-like coat color) rats develop hepatocellular carcinomas (HCCs) spontaneously. We examined mutations of codons 12, 13, and 61 of the Ha-ras, Ki-ras, and N-ras genes in four HCCs by the polymerase chain reaction (PCR)-single-stranded DNA direct sequencing method. No ras gene mutations were observed, suggesting that ras activation is not involved in spontaneous hepatocarcinogenesis in LEC rats. The expression of mRNAs for c-myc, Ha-ras, c-raf, and the protein phosphatase 2A alpha gene (PP-2A alpha) was also examined in the four HCCs by northern blot analysis. Three of the four HCCs had c-myc expression levels approximately 30-fold higher than that in the liver of control Long-Evans rats with an agouti coat color (LEA), a sibling line of LEC rats, while the remaining HCC had an expression level sevenfold higher than that of control. In contrast, the expression levels of the Ha-ras, c-raf, and PP-2A alpha genes were the same as those in the livers of control rats. Studies of c-myc expression and mitotic index in five other HCCs, two hyperplastic nodules, and two nontumorous portions of livers of HCC-bearing LEC rats that had chronic-phase hepatitis suggested that the high level of c-myc gene expression was not due only to increased cell proliferation but might possibly be more integrally involved in hepatocarcinogenesis.     

High Sensitivity of LEC Rats with Chronic Hepatitis to Hepatocarcinogenesis: Decreases in Unscheduled and Replicative DNA Synthesis of the Hepatocytes

We carried out the following three experiments to clarify the mechanism of hepatocarcinogenesis in Long-Evans Cinnamon (LEC) rats. (1) Sensitivity to diethylnitrosamine (DEN): LEC rats (8 and 25 weeks old) without and with hepatitis and age-matched F344 rats were administered an intraperitoneal injection of a low dose of DEN. Eight weeks after the injection, the numbers of glutathione-S-transferase placental-form (GST-P)-positive foci in the 33-week-old LEC rat liver were significantly higher than those in the livers of the other three groups of rats. (2) Potential for unscheduled DNA synthesis (UDS): Isolated hepatocytes of 25-week-old LEC rats with chronic hepatitis showed about one-third the level of UDS induced by UV irradiation, as compared to that of age-matched F344 rats, while no significant difference was found between the UDS of isolated hepatocytes of 8-week-old LEC rats and age-matched F344 rats. (3) Potential for proliferation: Isolated hepatocytes from 8-week-old LEC rats responded well to epidermal growth factor (EGF) in culture, to almost the same degree as F344 rat hepatocytes, while a remarkable decrease in the responsiveness of hepatocytes isolated from 25-week-old LEC rats to EGF was found. These results suggested that LEC rat hepatocellular carcinoma could be naturally initiated after the onset of hepatitis by carcinogens contaminating food and the environment, probably due to the reduction of DNA repair activity, after which initiated hepatocytes selectively proliferate in response to growth stimuli endogenously produced as a result of continuous loss of hepatocytes (chronic hepatitis), because of a decrease in growth activity of non-initiated hepatocytes.     

Long-Evans A and C Rat Strains Susceptible to Clastogenic Effects of Chemicals in the Bone Marrow Cells

The Clastogenic responses to direct- and indirect-acting carcinogens in bone marrow cells of LEA, LEC, Wistar and SD rats were compared. The frequency of chromosome aberrations (CA) induced by n -butyl-N-nitrosourea or methylmethanesulfonate (MMS), which does not need metabolic activation, was significantly higher in both LEA and LEC rats than in Wistar or SD rats. When bone marrow cells of each rat strain were exposed to MMS in vitro , they also showed the same tendency in CA frequency. Therefore, the high sensitivity of both LEA and LEC rats to the Clastogenic effects of direct-acting carcinogens seems to result from the sensitivity of the bone marrow cells themselves. On the other hand, the CA frequency induced by 7,12-dimethylbenz[a]anthracene (DMBA) or aflatoxin bi (AFB₁), which requires metabolic activation, was lower in LEC rats than in the other 3 strains. The CA frequency induced by DMBA or AFB₁ in LEC rats fed Cu-free diet since birth (Cu-free LEC rats) was higher than that in LEC rats given normal diet and lower than that in LEA rats, although the difference was statistically significant only between Cu-free LEC rats and LEC rats treated with DMBA. The copper concentrations in the livers of LEA, Cu-free LEC and LEC male rats aged 4 weeks were 5.0 ±0.4, 33 ±7.7 and 106±3.4 μg/g wet weight, respectively. These results suggest that the lower sensitivity of LEC rats to the Clastogenic effects of indirect-acting carcinogens may be due to the effect of the large amount of copper accumulated in LEC rat liver.     

LEC法在某新建项目职业病危害预评价中的应用

目的探讨作业条件危险性评价(LEC法)在某新建冶金项目职业病危害预评价中的应用。方法根据L-发生事故的可能性,E-人体暴露在危险环境中的频繁程度,C-一旦发生事故可能造成的损失后果;以3个因素分值的乘积D来评价危险性的大小。结果项目初期评价指数在20～70,属于一般危险;在采取了相应防护措施后评价指数小于20,属于稍有危险,可以接受的项目。结论在采取一定的防护和管理措施的情况下,该建设项目可以减少发生职业病危害的风险。