c-Abl蛋白酪氨酸激酶形成同源二聚体

c-Abl是非受体酪氨酸激酶,它在细胞内被一些基因毒性的、氧化的及其它形式的压力所激活。目前研究证明：应用标记的c-Abl发现其在细胞内可以相互形成同源二聚体,并且一分子c-Abl的N末端区域与相应的另一分子的C末端相互作用形成二聚体。实验进一步表明： cAbl SH3 结构域结合到另一c-Abl 分子富含脯氨酸的C-末端约958-982氨基酸区域。如果去除c-Abl 富含脯氨酸的结构域,就会阻止二聚体的形成。这些结果首先证实了c-Abl在细胞内可以相互形成同源二聚体,并暗示着二聚体的形成可能影响着c-Abl活性的调节。     

Effect of nano-TiO2 on photochemical reaction of chloroplasts of spinach

The effects of nano-TiO₂ (rutile) on the photochemical reaction of chloroplasts of spinach were studied. The results showed that when spinach was treated with 0.25% nano-TiO₂, the Hill reaction, such as the reduction rate of FeCy, and the rate of evolution oxygen of chloroplasts was accelerated and noncyclic photophosphorylation (nc-PSP) activity of chloroplasts was higher than cyclic photophosphorylation (c-PSP) activity, the chloroplast coupling was improved and activities of Mg²⁺-ATPase and chloroplast coupling factor I (CF₁)-ATPase on the thylakoid membranes were obviously activated. It suggested that photosynthesis promoted by nano-TiO₂ might be related to activation of photochemical reaction of chloroplasts of spinach.     

川芎嗪合并硫酸镁治疗妊高征大鼠的疗效及机制探讨

The aim of this study was to evaluate the outcome of treatment of pregnancy--induced hypertension (PIH) in rats by Ligustrazine collaborated with magnesium sulfate. PIH rat models were induced with Nomega-nitro-L-arginine methyl ester (L-NAME) infusing at 7 mg/kg per day via caudal vein for four days, then treated with Ligustrazine, magnesium sulfate, or both for three days. Rat blood pressure level was measured by the tail-cuff method, 24 hours urine protein was also assayed. The blood pressure and urine proteins of grouped PIH rats were recorded before the start and after the termination of therapy. The body length and the weight of fetal rats, the weight of placentals from pregnant rats were measured. The placental tissues, livers, kidneys of rats were investigated with integrated methods such as histopathologic observation with light microscopy, ultrastructural observation with transmission electron microscopy. L-NAME administration in pregnancy rats during the late pregnancy period had resulted in an rise of blood pressure, an increasing of urine protein, death rate of rat fetus, incidence of teratogenesis, and so on. Three groups of PIH rats treated with single magnesium sulfate, Ligustrazine, or Ligustrazine combined with magnesium sulfate showed an obvious dropping of the proteinuria, decompression of blood pressure (p<0.01, p<0.001), especially the treatment efficacy in the group of Ligustrazine combined with magnesium sulfate was more significant effective than other two groups (p<0.01, p<0.001). The treatment with both Ligustrazine and magnesium sulfate could increase the body length of newly born rats, the body weight of tomites and the placental weight, furthermore, reduce the rate of the teratosis of hindlimb-shortness (p<0.001). There were diffuse focal necrosis areas in the livers of PIH rats, their glomerular basement membrane had thickened extensively, the glomerular endothelium had swelled, extensive edema in the epithelia of renal tubule was demonstrated. The decidua and basal zone of the placentae of PIH rats all thickened, the microvilli of trophoblasts decreased. After treatment with ligustrazine especially with both Ligustrazine and magnesium sulfate, the necrosis of hepatocytes disappeared. The thickening of glomerular basement membrane in the group of ligustrazine or both Ligustrazine and magnesium sulfate treatment reduced; Moreover in the latter group the morphology of glomerular endothelium essentially recovered, the edema in cytoplasms of renal tubular epithelium reduced. The placental lesions were also relieved. The present results indicated the therapeutic effect by Ligustrazine collaborated with magnesium sulfate was better than a single use of Ligustrazine or magnesium sulfate. There were pathological alteration involved ischemia and anoxic in the placental tissues of PIH rats, resembled the placental pathological alteration of the human cases with PIH. The treatment with ligustrazine, and especially both Ligustrazine and magnesium sulfate in PIH rats could obviously relieve the lesions in lives, kidneys and placentae.     

中国人胃癌染色体17q21区域基因遗传不稳定性研究

To investigate microsatellite instability (MSI) and loss of heterozygosity (LOH) of locus D17S396, D17S579 and D17S855, and their effect on the expression of nm23H1 and BRCA1 of gastric cancer, which would provide experimental basis for clinical treatment and prognosis analysis of gastric cancer. DNA was extracted from paraffin-embedded materials. Polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) was used to analyze MSI and LOH. Expression of nm23H, and BRCA1 was detected by Envision immuno-histochemistry and Leica-Qwin computer imaging techniques. In the forty cases of gastric cancer, the frequency of MSI, LOH and nm23H1 protein were 20.00%, 17.50% and 55.00% respectively at locus D17S396, while at locus D17S579, the frequency of MSI, LOH and BRCA1 protein were 22.50%, 15.00% and 37.50% respectively; at locus D17S855, the frequency of MSI, LOH and BRCA1 of thirty-seven cases were 18.92%, 18.92%, 37.84% respectively. In tumor node metastasis (TNM) staging, at locus D17S396, D17S579 and D17S855, MSI in stages I + II appeared more frequently than that in stages III + IV, while LOH appeared the contrary tendency. In the group of metastasis of gastric cancer, MSI had a less frequency (5.00%) than that with no metastasis (35.00%, P < 0.05) at locus D17S396, but LOH appeared more frequently (30.00%) than that with no metastasis (5.00%, P < 0.05). At locus D17S579, MSI had an increasing tendency with the degree of tumor differentiation (50.00% in high differentiation cases, 20.00% in middle differentiation cases, and 0% in low differentiation cases, P < 0.05). The frequency of nm23H1 and BRCA1 protein in stages TNM I + II was higher than that in stages TNM III + IV; and that in higher differentiation cases was higher than in poor differentiation cases. The frequency of nm23H1 protein in the group of metastasis (30.00%) was less than that with no metastasis significantly (80.00%, P<0.01). The frequency of nm23H1 protein in the group positive to MSI (87.50%) was higher than that in the group negative to MSI (46.88%, P < 0.05). However, nm23H1 protein in group positive to LOH (14.29%) was lower than that in the group negative to LOH (63.64%, P < 0.05). The frequency of BRCA1 protein in the group positive to MSI (66.67%) was more than that in the group negative to MSI (29.03%, P < 0.05). The results of experiments indicate that MSI and LOH may separately control the development of sporadic colon cancer with different pathways. MSI may be an early period molecule marker for sporadic colon cancer, enhanced expression of nm23H1 protein can effectively inhibit colon cancer metastasis and improve prognosis of sporadic colon cancer patients. By comparison, LOH mostly arises in the late period of sporadic colon cancer and endows a high aggressive and poor prognostic phenotype. nm23H1 protein could effectively restrain gastric cancer metastasis and development; and BRCA1 protein could restain tumor from becoming lower differentiation.     

A novel GTP-binding protein hGBP3 interacts with NIK/HGK

A novel human guanylate-binding protein (GBP) hGBP3 was identified and characterized. Similar as the two human guanylate-binding proteins hGBP1 and hGBP2, hGBP3 has the first two motifs of the three classical guanylate-binding motifs, GXXXXGKS (T) and DXXG, but lacks the N (T) KXD motif. Escherichia coli-expressed hGBP3 protein specifically binds to guanosine triphosphate (GTP). Using a yeast two-hybrid system, it was revealed that the N-terminal region of hGBP3 binds to the C-terminal regulatory domain of NIK/HGK, a member of the group I GCK (germinal center kinase) family. This interaction was confirmed by in vitro glutathione-S-transferase (GST) pull-down and co-immunoprecipitation assays.     

黄土区不同恢复年限草地群落生物量及根冠比对氮添加的响应

大气氮沉降增加作为全球变化的主要环境问题之一,已引发人们的广泛关注,持续的氮沉降对草地生态系统的组成、结构和功能产生重要影响。为深入了解草地恢复进程中群落生物量和根冠比对氮沉降的响应,以黄土区3个不同恢复年限（初期12a、中期28a和后期37a）的天然草地为研究对象,通过设置6个氮添加水平,CK （0）、N1（2.34g m^-2a^-1）、N2（4.67g m^-2a^-1）、N3（9.34g m^-2a^-1）、N4（18.68g m^-2a^-1）、N5（37.35g m^-2a^-1）来测定草地群落地上生物量、地下生物量和总生物量,并计算根冠比和氮响应效率（NRE）。结果表明：（1）地上生物量在恢复中期最大,随氮添加梯度增加,地上生物量在恢复初期和恢复后期呈不显著上升趋势,对氮添加表现为非线性的正响应（ΔNRE>0）,在恢复中期呈不显著下降趋势,对氮添加表现为非线性的负响应（ΔNRE<0）。（2）群落地下生物量对氮添加无显著响应,总生物量只有在恢复后期的N4添加水平下,与对照存在显著差异。（3）根冠比在恢复初期时,N3添加水平下显著高于对照和其他氮添加水平,其余恢复年限对氮添加无显著响应。综上所述,通过分析比较黄土区不同恢复年限草地群落的地上、地下及总生物量和根冠比对氮添加的响应。建议对该区域开展试点实验,实行适应性草地管理,如进行两年一次刈割或轻度放牧（2只羊/hm²）,来探寻更科学有效的管理措施,使草地实现系统性恢复,进而满足生态系统容量和社会需求的变化。     

Gypenosides alleviate myocardial ischemia-reperfusion injury via attenuation of oxidative stress and preservation of mitochondrial function in rat heart

Gypenosides (GP) are the predominant components of Gynostemma pentaphyllum, a Chinese herb medicine that has been widely used for the treatment of chronic inflammation, hyperlipidemia, and cardiovascular disease. GP has been demonstrated to exert protective effects on the liver and brain against ischemia-reperfusion (I/R) injury, yet whether it is beneficial to the heart during myocardial I/R is unclear. In this study, we demonstrate that pre-treatment with GP dose-dependently limits infarct size, alleviates I/R-induced pathological changes in the myocardium, and preserves left ventricular function in a rat model of cardiac I/R injury. In addition, GP pre-treatment reduces oxidative stress and protects the intracellular antioxidant machinery in the myocardium. Further, we show that the cardioprotective effect of GP is associated with the preservation of mitochondrial function in the cardiomyocytes, as indicated by ATP level, enzymatic activities of complex I, II, and IV on the mitochondrial respiration chain, and the activity of citrate synthase in the citric acid cycle for energy generation. Moreover, GP maintains mitochondrial membrane integrity and inhibits the release of cytochrome c from the mitochondria to the cytosol. The cytoprotective effect of GP is further confirmed in vitro in H9c2 cardiomyoblast cell line with oxygen-glucose deprivation and reperfusion (OGD/R), and the results indicate that GP protects cell viability, reduces oxidative stress, and preserves mitochondrial function. In conclusion, our study suggests that GP may be of clinical value in cytoprotection during acute myocardial infarction and reperfusion.     

Prevalence of Sarcopenia and Its Relationship with Sites of Fragility Fractures in Elderly Chinese Men and Women

Objective

Sarcopenia might be associated with bone fragility in elderly individuals. This study aimed to investigate the prevalence of sarcopenia and its association with fragility fracture sites in elderly Chinese patients.

Methods

Patients (322 men and 435 women) aged 65–94 years and with a history of fragility fractures in the ankle, wrist, vertebrae or hip, and healthy men (n = 1263) and women (n = 1057) aged 65–92 years without a history of fractures were enrolled. Whole-body dual energy X-ray absorptiometry was used to analyze skeletal muscle mass index (SMI), fat mass and bone mineral density. Sarcopenia was defined as SMI less than two standard deviations below the mean of a young reference group.

Results

Sarcopenia occurrence varied with fracture location. Sarcopenia was more common in females with vertebral and hip fractures and in men with hip and ankle fractures than in the non-fracture group). Sarcopenia was significantly more prevalent in men with wrist, hip and ankle fractures than in women. SMI was correlated with BMD in different fracture groups. Logistic regression analyses revealed that lower SMI was associated with an increased risk of hip fracture both in men and women and ankle fracture in men.

Discussion

Sarcopenia may be an independent risk factor for hip and ankle fractures in men, and for hip fractures in women.     

Selective growth of a mutant in continuous culture of Bacillus caldolyticus for production of α-amylase

Summary In a continuous culture of Bacillus caldolyticus strain SP, which requires maltose as an inducer for production of -amylase in batch culture, a predominant mutant strain M1 which produced high amounts of -amylase in the absence of maltose in batch culture, developed. The change of cell population from strain SP to strain M1 in maltose-casitone medium was linear with time in the transient state after the change from batch to continuous culture at a dilution rate of 0.17 h^-1, and was completed in about 11 generations of bacterial growth. The dilution rate effect of continuous culture on -amylase activity was almost the same with both strains SP and M1. The maximum -amylase activity of 380 units/ml was observed at an intermediate dilution rate that was 11.5 times higher than -amylase activity at the end of a batch culture using the same medium. It was deduced that the enhancement of -amylase production in continuous culture was attributed partly to the predominant growth of a mutant strain with higher -amylase productivity.