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1.
INTRODUCTION Telomeres are distinctive DNA-protein struc-tures that cap the ends of linear chromosomes.It is very important to keep the chromosomes stabilization.Telomerase activity is closely linked to attainment of cellular immortality,a step in carcinogenesis,while lack of such activity contributes to cellular senes-cence.Telomerase is activated in more than85%ofmalignant tumors(Hiayma et al.,1997).Human te-lomeric repeat binding factor1(TRF1)is a telomere associated with proteins a…  相似文献   

2.
１ＩｎｔｒｏｄｕｃｔｉｏｎＤｉｆｅｒｅｎｔｉａｌｅｑｕａｔｉｏｎｓｗｉｔｈｔｕｒｎｉｎｇｐｏｉｎｔｓｅｘｉｓｔｗｉｄｅｌｙｉｎｍａｎｙｐｒｏｂｌｅｍｓｏｆｍａｔｈｅｍａｔｉｃｓｐｈｙｓｉｃｓ,ｓｏｔｈｅｓｅｐｒｏｂｌｅｍｓａｒｅｖｅｒｙｉｍｐｏｒｔａ...  相似文献   

3.
INTRODUCTION With the development of modern electronics,there is a growing trend of designing a low-voltagehigh precision current reference in many mixed-signaland analog circuits such as data converters (Mehr andSinger, 2000; Oh et al., 2004), oscillators and PLLs(Razavi, 2001; Banba and Shiga, 1999). Low-costreasons need the reference to be realized in simplestandard CMOS logic process technology, withoutresorting to the use of BiCMOS process and specialdevices such as floating-g…  相似文献   

4.
Objective: To investigate the influence of lead exposure on the immune function of lymphocytes and erythrocytes in preschool children. Materials and methods: A group of 217 children three to six years of age from a rural area were given a thorough physical examination and the concentration of lead in blood samples taken from each subject was determined. The indices of lymphocyte immunity (CD 3CD 4, CD 3CD 8, CD 4CD 8, CD-3CD 19) and erythrocyte immunity (RBC-C3b, RBC-IC, RFER, RFIR, CD35 and its average fluorescence intensity) of 40 children with blood lead levels above 0.483 μmol/L were measured and compared with a control group. Results: The blood lead levels of the 217 children ranged from 0.11 μmol/L to 2.11 μmol/L. The CD 3CD 4and CD 4CD 8 cells were lower (P＜0.01) and the CD 3CD 8 cells were higher in the lead-poisoned subjects than those in the control group (P＜0.05). CD 3 and CD-3CD 19 did not show significant differences. Although the RBC-C3b rosette forming rate was lower and the RBC-IC rosette forming rate was higher in the lead-poisoned group, this difference could not be shown to be statistically significant (P＞0.05). RFIR was found to be lower in the lead-poisoned group (P＜0.01). Compared with the control group, the positive rate of CD35 was not found to be significantly different in a group of 25 lead-poisoned children (P＞0.05), while the average fluorescence intensity was lower in the lead-poisoned group (P＜0.05). Conclusion: Lead exposure can result in impaired immune function of T lymphocytes and erythrocytes in preschool children.  相似文献   

5.
Turmeric has long been used as a spice and food colouring agent in Asia. In the present investigation, the antimutagenic potential of curcumin was evaluated in Allium cepa root meristem cells. So far there is no report on the biological properties of curcumin in plant test systems. The root tip cells were treated with sodium azide at 200 and 300 μg/ml for 3 h and curcumin was given at 5, 10 and 20 μg/ml for 16 h, prior to sodium azide treatment. The tips were squashed after colchicine treatment and the cells were analyzed for chromosome aberration and mitotic index. Curcumin induces chromosomal aberration in Allium cepa root tip cells in an insignificant manner, when compared with untreated control. Sodium azide alone induces chromosomal aberrations significantly with increasing concentrations. The total number of aberrations was significantly reduced in root tip cells pretreated with curcumin. The study reveals that curcumin has antimutagenic potential against sodium azide induced chromosomal aberrations in Allium cepa root meristem cells. In addition, it showed mild cytotoxicity by reducing the percentage of mitotic index in all curcumin treated groups, but the mechanism of action remains unknown. The antimutagenic potential of curcumin is effective at 5 μg/ml in Allium cepa root meristem cells.  相似文献   

6.
Disturbances in the metabolism of lipoprotein profiles and oxidative stress in hemodialyzed (HD) and post-renal transplant (Tx) patients are proatherogenic, but elevated concentrations of plasma high-density lipoprotein (HDL) reduce the risk of cardiovascular disease. We investigated the concentrations of lipid, lipoprotein, HDL particle, oxidized low-density lipoprotein (ox-LDL) and anti-ox-LDL, and paraoxonase-1 (PON-1) activity in HD (n=33) and Tx (n=71) patients who were non-smokers without active inflammatory disease, liver disease, diabetes, or malignancy. HD patients had moderate hypertriglyceridemia, normocholesterolemia, low HDL-C, apolipoprotein A-I (apoA-I) and HDL particle concentrations as well as PON-1 activity, and increased ox-LDL and anti-ox-LDL levels. Tx patients had hypertriglyceridemia, hypercholesterolemia, moderately decreased HDL-C and HDL particle concentrations and PON-1 activity, and moderately increased ox-LDL and anti-ox-LDL levels as compared to the reference, but ox-LDL and anti-ox-LDL levels and PON-1 activity were more disturbed in HD patients. However, in both patient groups, lipid and lipoprotein ratios (total cholesterol (TC)/HDL-C, LDL-C/HDL-C, triglyceride (TG)/HDL-C, HDL-C/non-HDL-C, apoA-I/apoB, HDL-C/apoA-I, TG/HDL) were atherogenic. The Spearman’s rank coefficient test showed that the concentration of ox-LDL correlated positively with HDL particle level (R=0.363, P=0.004), and negatively with TC (R=−0.306, P=0.012), LDL-C (R=−0.283, P=0.020), and non-HDL-C (R=−0.263, P=0.030) levels in Tx patients. Multiple stepwise forward regression analysis in Tx patients demonstrated that ox-LDL concentration, as an independent variable, was associated significantly positively with HDL particle level. The results indicated that ox-LDL and decreased PON-1 activity in Tx patients may give rise to more mildly-oxidized HDLs, which are less stable, easily undergo metabolic remodeling, generate a greater number of smaller pre-β-HDL particles, and thus accelerate reverse cholesterol transport, which may be beneficial for Tx patients. Further studies are necessary to confirm this.  相似文献   

7.
１　Ｉｎｔｒｏｄｕｃｔｉｏｎ　Ｓｉｎｇｕｌａｒｌｙｐｅｒｔｕｒｂｅｄｄｉｆｆｅｒｅｎｔｉａｌｅｑｕａｔｉｏｎｓｗｉｔｈｔｕｒｎｉｎｇｐｏｉｎｔｓａｒｅｖｅｒｙｉｍｐｏｒｔａｎｔｆｏｒｍａｔｈｅｍａｔｉｃｉａｎｓａｎｄｐｈｙｓｉｃｉｓｔｓｓｉｎｃｅｔｈｅｓｅｐｒｏｂｌｅｍｓｅｘｉｓｔｗｉｄｅｌｙｉｎｍａｎｙｐｒｏｂｌｅｍｓｏｆｐｈｙｓｉｃｓ．ＴｈｅｐｒｏｂｌｅｍｓｗｉｔｈｔｕｒｎｉｎｇｐｏｉｎｔｓｗｅｒｅｓｔｕｄｉｅｄｂｙＷｅｎｔｚａｌ,Ｋｒａｍｅｒｓ,Ｂｕｌｌｏｕｎｉｎ［１］,Ｌａｎｇｅｒ,Ａ…  相似文献   

8.
In order to comply with the requirements for a drug listed in China, the study was developed to compare the pharmacokinetics and relative bioavailability of two different enteric formulations of omeprazole (OPZ) in healthy Chinese subjects. A total of 32 volunteers participated in the study. Plasma concentrations were analyzed by nonstereospecific liquid chromatography/tandem mass spectrometric (LC-MS/MS) method. After administration of a single 40-mg dose of the two OPZ formulations, the comparative bioavailability was assessed by calculating individual AUC0−t (the area under the concentration-time curve from time zero to the last measurable concentration), AUC0−∞ (the area under the concentration-time curve extrapolated to infinity), C max (the maximum observed concentration), and T peak (the time to C max) values of OPZ, 5-hydroxyomeprazole (OH-OPZ), and omeprazole sulfone (OPZ-SFN), respectively. The 90% confidence intervals (CIs) of AUC0−t , AUC0−∞, and C max were 85.4%–99.0%/88.8%–98.6%/87.6%–99.4%, 85.5%–99.2%/89.0%–98.6%/88.5%–101.3%, and 72.3%–87.6%/79.6%–91.1%/88.4%–99.1% for OPZ/OH-OPZ/OPZ-SFN, respectively, and T peak values did not differ significantly. In this study, the test formulation of OPZ in fasting healthy Chinese male volunteers met the Chinese bioequivalance standard to the reference formulation based on AUC, C max, and T peak.  相似文献   

9.
INTRODUCTION Throughout this paper, we shall work with a filtered complete probability space (?,F,(Ft),P) sat-isfying the usual conditions. Let B=(Bt)t≥0 be a stan-dard Brownian motion with B0=0. Denote by ú the set of all non-negative real numbers. Recall that a diffusion process X starting at x≥0 is called the square of a Bessel process of dimension δ>0 if d X t = δd t 2 | X t |d Bt , X 0= x, (1) Clearly, this equation has a unique non-negative strong solution X, i.e., …  相似文献   

10.
Exchange coupling and magnetization reversal mechanism in two series of Co_xNi_(1-x)/CoO(30 nm)(x=0.2 and 0.4)bilayers are studied by vector magnetometer.Two components of magnetization are measured parallel and perpendicular to the applied field.At low temperatures,coercivity H_c∝(t_(FM))~(-n),n=1.5 and 1.38 for x=0.2 and 0.4,respectively,in agreement with the random field model.At room temperature,the coercivity is nearly proportional to the inverse FM layer thickness.In addition to the exchange field and the coercivity,the characteristic of the magnetization reversal mechanism was found to change with temperature.At temperatures below 180 K,magnetization reversal process along the unidirectional axis is accompanied only by nucleation and pinning of domain wall while magnetization rotation is also involved at high temperatures.  相似文献   

11.
Sap flow and environmental conditions were monitored at two Eucalyptus (Eucalyptus urophylla S.T. Blake) plantations at Hetou and Jijia, located in Leizhou, Zhanjiang, Guangdong Province. It was found that daily sap flux density (SFD) of Eucalyptus was closely related to daily atmospheric vapor pressure deficit (VPD) (R 2=0.76, P=0.01 at Hetou and R 2=0.7021, P=0.01 at Jijia) at both sites. No significant relationship existed between daily SFD and mean daily air temperature at both sites. Daily SFD varied with wind speed Y=−17585X 3+15147X 2−1250.7X+2278.4 (R 2=0.68; P=0.01) at Hetou and Y=−101.67X 3−1.65X 2−376.4X+1914.8 (R 2=0.40, P=0.05) at Jijia, where Y was daily SFD, X was daily wind speed. Experimental observations yielded the following data: (1) the critical lower and upper daily VPD threshold were 0 and 2 kPa, within which daily SFD varied from 540±70 L/(m2·d) to 4739±115 L/(m2·d) at Hetou site, from 397±26 L/(m2·d) to 3414±191 L/(m2·d) at Jijia site; (2) Diurnal SFDs at Hetou site were much higher under low relative humidity (<30%) and slightly lower under high relative humidity (>80%) compared with those at the Jijia site; (3) The upper and lower threshold of daily and diurnal RAD for the optimal water use of E. urophylla plantations were 18±2.7 and 2±1 MJ/(m2·d), 669 and 0 J/(cm2·h) during the observation period. Project supported by Knowledge Innovation Funds from Chinese Academy of Sciences (Nos. KSCX2-SW-120, KZCX1-SW-01-01A3) and the Key Project of Guangdong Natural Science Foundation (No. 010567), China  相似文献   

12.
This study assessed the effect of the course cycle on theoretical knowledge of dental morphology and the dental carving ability of dental students. Thirty-two dental students from the third semester (initial cycle) and 30 students from the eighth and tenth semesters of the dental course (end cycle) had their theoretical knowledge on dental morphology assessed using a questionnaire with ten closed questions. Their dental carving ability was also assessed using wax carvings in macro models of plaster (for the third [S3] and eight [S8] semesters) and natural-sized artificial teeth (for the tenth [S10] semester). The teeth chosen for the dental carving activity were #16 and #47. The scores were statistically analyzed using the t-test, Kruskal–Wallis test, and Mann–Whitney test (α = 0.05). Students from the initial cycle presented better theoretical knowledge than the other groups did (P < 0.007). No significant differences in carving score were found between the initial and end cycles (P > 0.05), although S10 students obtained a higher score for teeth #16 and #47 (P < 0.05). Natural-sized artificial teeth received a higher evaluation score in dental carvings than the macro models (P < 0.001). Within the limits of this study, it was possible to conclude that students from the initial cycle (S3) presented higher theoretical knowledge, whereas no difference in carving ability was observed between the initial and end cycles. The tenth semester (S10) students performed dental carvings with better quality. Furthermore, carvings in natural-sized artificial teeth presented better quality compared with the macro models.  相似文献   

13.
To assess the influence of cyclosporin A (CsA) and tacrolimus (FK506) on mycophenolic acid (MPA) and correlation analysis of the pharmacokinetic parameters and patient characteristics, clinical outcome in Chinese kidney transplant recipients, the pharmacokinetics of 1000 mg mycophenolate mofetil (MMF) twice daily was measured by high-performance liquid chromatography (HPLC). PKS (Pharmaceutical Kinctics Software) 1.0.2 software package was used for the calculation of pharmacokinetic parameters. The meanC max,t max, and AUC(0–12) were (21.88±10.52) μg/ml, (1.20±0.95) h, and (52.546±13.215) μg·h/ml, respectively. The level of AUC(0–12) in the FK506 group was significantly higher than that in the CsA group. MPA appeared not to be affected by renal function. MPA AUC(0–12) showed statistically significant difference according to the patient's gender. Project (No. 20040462) supported by the Foundation of Education Bureau of Zhejiang Province, China  相似文献   

14.
1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　Ｔｈｅｆｕｎｄａｍｅｎｔａｌｐｈｙｓｉｃａｌｍｅｔａｌｌｕｒｇｙｏｆｔｈｅｒｍｏｍｅｃｈａｎｉｃａｌｐｒｏｃｅｓｓｉｎｇ(ＴＭＰ)ｈａｓｂｅｃｏｍｅｍｕｃｈｂｅｔｔｅｒｕｎｄｅｒｓｔｏｏｄｏｖｅｒｔｈｅｌａｓｔｔｗｏｄｅｃａｄｅｓ[1～8].ＩｔｉｓｗｅｌｌｃｏｍｍｏｎｌｙｒｅｃｏｇｎｉｚｅｄｔｈａｔｔｈｅｍｉｎｕｔｅａｄｄｉｔｉｏｎｏｆｓｔｒｏｎｇｃａｒｂｏｎｉｔｒｉｄｅｏｒｎｉｔｒｉｄｅｆｏｒｍｉｎｇｅｌｅｍｅｎｔｓｓｕｃｈａｓＮｂ,ＴｉａｎｄＶｔａｋｅｓｖｅｒｙｉｍｐ…  相似文献   

15.
Seeds of a Chinese traditional medicine plant, Cochinchina momordica were used in the present study for the improvement of influenza vaccine （HSN 1） in chicken. Crude extraction from Cochinchina momordica seed （ECMS） was obtained by ethanol extraction method. In experiment No. 1, two weeks old chickens were immunized with influenza vaccine （HSN1） alone or combined with ECMS （5, 10, 20, 40 and 80 μg/dose）. Serum IgG antibody levels （by ELISA） as well as effects on dally weight gain were measured on 0, 7, 14 and 28th day after immunization. Results revealed that all ECMS groups numerically increased the antibody levels while 10 and 20 μg/dose groups significantly （P〈0.05） enhanced total IgG antibody on day 28, when compared with control. Average daily weight gain was also significantly higher in 20 μg/dose ECMS group. Adjuvant effect was also confirmed in experiment No. 2 when chickens were immunized with 20 μg/dose ECMS and antibody titer was measured through hemagglutination inhibition （HI）. It is concluded that ECMS has potential to improve the immune responses and deserve further study as an adjuvant.  相似文献   

16.
Let K be a closed convex subset of a real reflexive Banach space E, T：K→K be a nonexpansive mapping, and f：K→K be a fixed weakly contractive （may not be contractive） mapping. Then for any t∈（0, 1）, let x1∈K be the unique fixed point of the weak contraction x1→tf（x）＋（1-t）Tx. If T has a fixed point and E admits a weakly sequentially continuous duality mapping from E to E^＊, then it is shown that {xt} converges to a fixed point of T as t→0. The results presented here improve and generalize the corresponding results in （Xu, 2004）.  相似文献   

17.
This study describes the sense-making behaviors of sixth- and seventh-grade students (n = 46 dyads) as they read and discussed expository articles in print and digital formats. Most dyads approached the digital text as if it were static and linear, despite the availability of hyperlinks. Reading through (or covering) the text was the most commonly observed behavior, occurring in 89% of the coded intervals in the print condition and 76% of intervals in the digital condition. Students were observed discussing a variety of cognitive and metacognitive strategies. The most common strategies were process monitoring, summarizing, connecting, and reacting. The dyads used at least one overt sense-making strategy in about 50% of the intervals when reading the print text and about 65% of the intervals with the digital text. Previewing and progress monitoring, which serve important planning and self-regulative functions, were used more frequently in the digital condition. Regression analyses show that several collaborative behaviors were associated with text comprehension, as measured by a researcher-designed multiple choice test, in the print condition but not in the digital condition. These included word recognition monitoring (β = 1.84; SE = 0.90; p = .05), summarizing (β = 2.43; SE = 1.21; p = .05), and connecting (β = −5.20; SE = 2.06; p = .02) at the student level and attending to illustrations (γ = −7.08; SE = 2.17; p = .003) at the dyad level. In both conditions, prior reading achievement and prior knowledge were strong predictors of comprehension.  相似文献   

18.
The present study focused on investigating the effectiveness of instruction via newly developed teaching materials based on cooperative learning when compared to a traditional approach, on ninth grade students’ understanding of metallic bonding. Fifty-seven ninth grade science students from two science classes in the same high school participated in this study. The same teacher taught metallic bonding with cooperative learning to an experimental group (N = 28) and with a traditional teacher centred approach to a control group (N = 29). Students’ conceptual understanding of metallic bonding was measured using the Metallic Bonding Concept Test. The results from the Student’s t test indicated that the mean score of the students in the experimental group was significantly higher in the experimental group (78.60, SD = 8.62), than in the control group (54.33, SD = 9.11) after treatment. In the light of the results from the concept test and individual interviews, the misconceptions related to metallic bonding were found less in the experimental group than traditional. Five of these misconceptions were firstly identified in this study. The individual interviews which were done with students from experimental group immediately after the instruction showed that students had positive perceptions about their cooperative work experiences.  相似文献   

19.
A laboratory incubation experiment was conducted to study the effect of copper as cupric sulfate (CuSO4.5H2O), and lead as lead acetate (Pb (OAc)2) on the size of the microbial biomass in red soil. The metals were applied, separately at six different levels: Cu at 50, 100, 200, 300, 400, and 600 μg·g−1 soil and Pb at 100, 200, 400, 600, 800, and 1000 μg·g−1 soil. In comparison to uncontaminated soil, the microbial biomass carbon (Cmic) and biomass nitrogen (Nmic) decreased sharply in soils contaminated with Cu and Pb. The microbial biomass C:N ratio in the metal contaminated soil was observed to be considerably higher than that in untreated control. Between the two tested metals, Cu displayed greater biocidal effect on microbial biomass carbon and nitrogen than Pb, showing their relative toxicity in the order: Cu≫Pb. Project (No. 49671050) supported by National Natural Science Foundation of China. Wa’el Mohamad—Former Ph. D. Student of Zhejiang University and is working in Ministry Of Agriculture (P. O. box. 2099), Amman, Jordan.  相似文献   

20.
Sevoflurane postconditioning reduces myocardial infarct size.The objective of this study was to examine the role of the phosphatidylinositol-3-kinase(PI3K)/Akt pathway in anesthetic postconditioning and to determine whether PI3K/Akt signaling modulates the expression of pro-and antiapoptotic proteins in sevoflurane postconditioning.Isolated and perfused rat hearts were prepared first,and then randomly assigned to the following groups:Sham-operation(Sham),ischemia/reperfusion(Con),sevoflurane postconditioning(SPC),Sham plus 100 nmol/L wortmannin(Sham+Wort),Con+Wort,SPC+Wort,and Con+dimethylsulphoxide(DMSO).Sevoflurane postconditioning was induced by administration of sevoflurane(2.5%,v/v) for 10 min from the onset of reperfusion.Left ventricular developed pressure(LVDP),left ventricular end-diastolic pressure(LVEDP),maximum increase in rate of LVDP(+dP/dt),maximum decrease in rate of LVDP(?dP/dt),heart rate(HR),and coronary flow(CF) were measured at baseline,R30 min(30 min of reperfusion),R60 min,R90 min,and R120 min.Creatine kinase(CK) and lactate dehydrogenase(LDH) were measured after 5 min and 10 min reperfusion.Infarct size was determined by triphenyltetrazolium chloride staining at the end of reperfusion.Total Akt and phosphorylated Akt(phospho-Akt),Bax,Bcl-2,Bad,and phospho-Bad were determined by Western blot analysis.Analysis of variance(ANOVA) and Student-Newman-Keuls' test were used to investigate the significance of differences between groups.The LVDP,±dP/dt,and CF were higher and LVEDP was lower in the SPC group than in the Con group at all points of reperfusion(P0.05).The SPC group had significantly reduced CK and LDH release and decreased infarct size compared with the Con group [(22.9±8)% vs.(42.4±9.4)%,respectively;P0.05].The SPC group also had increased the expression of phospho-Akt,Bcl-2,and phospho-Bad,and decreased the expression of Bax.Wortmannin abolished the cardioprotection of sevoflurane postconditioning.Sevoflurane postconditioning may protect the isolated rat heart.Activation of PI3K and modulation of the expression of pro-and antiapoptotic proteins may play an important role in sevoflurane-induced myocardial protection.  相似文献   

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