The principle,structure and classification of magnetron of medical linear accelerator are expatiated.The maintenance of high voltage or the fault of the same kind of magnetron is put forward when the high voltage approaches or is surpassed.The diagnosis method is also given,thus improving the accuracy rate and repair rate and being helpful to medical practice.

Objective:To study the effects of CO_2 pneumoperitoneum on the signal transduction pathways of human cervical carcinoma cell line CasKi. Methods:The imitated CO_2 pneumoperitoneum model was established in vitro. After CasKi cells were exposed to CO_2 pneumoperitoneum at 12,13 or 14mmHg for 2h,the cell growth and expressions of phosphor-ERK and phosphor-Akt were examined by MTT,immunocytochemistry and Western blotting respectively. The untreated CasKi cells served as control. Results:After treatment of CO_2 pneumoperitoneum,the proliferation of human cervical carcinoma cell line CasKi significantly increased,and the expressions of phosphor-ERK and phosphor-Akt also significantly increased(P0.05). Conclusion:Under the pressure and during the exposure time which were often used in operational laparoscopy,CO_2 pneumoperitoneum could activate correlated signal transduction pathways,which may be one reason for the promoting effect of CO_2 pneumoperitoneum on malignant cells growth.

Objective:To introduce a new standardized logMAR visual acuity chart and its clinical application.Methods: The new visual acuity chart and notations were designed based on Weber-Fechner theorem.The E optotype on the chart had 3 limbs of equal length.A regular geometric progression of optotype sizes and distribution was employed to arrange 14 lines with 4 optotypes on each line.The progression rate of optotype size between 2 lines was 10 and the testing distance was 3 m.The visual acuity score could be recorded as logarithm of the minimum angle of resolution(logMAR) notation or decimal notation.The reliability of naked distant measurements with this new chart was tested in one eye of 100 subjects taking the Chinese national standard logarithm visual acuity chart(CSVAC) standard.Results: This new chart overcame the shortcomings of different number of optotypes on each line and fewer optotypes at the top of CSVAC.Several visual acuity notations were adopted and conversion between different notations was very convenient in this new chart.The measurements of this new chart had significant correlation and good agreement with CSVAC.Conclusion: The new standardized logMAR visual acuity chart is reliable,easy to use and accurate.It can be applied in clinical teaching and research of ophthalmology and optometry.

0. 05 ]. However, the level of sFas was significantly higher in the patients with CHF than those of the cardiac function class Ⅰ group [CHF group: 1353. 30 ? 507. 71 (cardiac function class Ⅱ 1154. 85 ? 371.20, class Ⅲ 1412. 88 ? 493. 62, class Ⅳ 1875.67 ? 806. 10) vs. cardiac function class Ⅰ group:983. 11 ? 416.26 pg/ml, P

The effects of methionine-enkephalin (M-EnK) on mitogenic and mixed lymphocyte culture (MLC) proliferation of splenocytes from Zn-deficient, restricted and control mice were evaluated. The data from this experiment showed that M-Enk could suppress the responses of splenocyte from th 3 groups to eoncanavalin A(Con A), but less inhibition was observed in the Zn-deficient group. M-Enk could also enhance the responses to Pokeweed Mitogen (PWM) and decrease the response to Lipopolysaceharide (LPS) in all groups. Alteration of proliferative responses to LPS,Con A and FWM was reversible in the presence of 10 ?mol/L naloxone, indicating that the effect of M-Enk on cellular proliferation was mediated by the opioid receptor. In the proliferation of MLC, the response of lymphocytes from Zndeficient mice was increased in the absence of M-Enk and M-Enk could suppress this increased response. It is therefore concluded that Met-Enk can modify the pattern of mitogenic responses and the alteration in Con A and MLC responses can be influenced by zinc deficiency.

Objective To analyze the correlation between chronic inflammation of vocal cords after the union and obstructive sleep apnea hypopnea syndrome (OSAHS),the predictive value to OSAHS.Methods One hundred and fifty-six cases of OSAHS patients underwent polysomnography (PSG) and fiber laryngoscopy,indexing based on the chronic inflammatory of vocal cords after the union.Apnea-hypopnea index (AHI),the lowest blood oxygen saturation and mean oxygen saturation were compared in different degrees patients.Mild,moderate,severe,very severe degree respectively had 32,70,36,18 cases.The patients were treated according to the cause and 1 and 3 months after treatment to determine efficacy.Results Following severity of chronic inflammation of vocal cords after the union,AHI gradually increased before treatment [mild,moderate,severe,very severe degree degree respectively (11.23 ±4.13),(21.23 ± 13.29),(44.53 ± 10.11),(56.56 ± 12.31) times/h],the lowest oxygen saturation and mean oxygen saturation decreased (mild,moderate,severe,very severe degree respectively 0.914 4 ±0.053 1 and 0.955 0 ± 0.041 2,0.834 2 ± 0.098 6 and 0.913 5 ±0.033 2,0.626 8 ±0.090 4 and 0.863 1 ±0.053 2,0.601 1 ± 0.101 1 and 0.752 1 ± 0.040 1),the differences were statistically significant (P ＜ 0.05).One month after treatment,the total effective rate was 75.64％ (118/156),3 months after treatment was 88.46％ (138/156).Conclusion Chronic inflammatory degree of vocal cords after the union is positively correlated with OSAHS,OSAHS patients according to etiological treatment have a significant effect.

Objective:To explore the changes of serum leptin in chronic congestive heart failure(CHF).Methods:The serum levels of leptin in 46 patients with NYHA cardiac function class Ⅰ and in 39 patients with CHF(14 in class Ⅱ,21 in class Ⅲ and 4 in class Ⅳ)were assessed by radioimmunoassay.Results:The serum contents of leptin were 11.674?6.911?g/l in NYHA class Ⅰ group,11.492?5.649 ?g/l in classⅡ group,7.763?3.321 ?g/l in class Ⅲ group,6.100? 2.657 ?g/l in class Ⅳ group and 9.018?4.519 ?g/l in CHF group.The serum levels of leptin were significantly lower in class Ⅲ group,class Ⅳ group and CHF group,compared with class Ⅰ group,respectively( t =2.185～2.786, P

Alpha fetoprotein(AFP) plays multi-role in regulating the growth of hepatocellular carcinoma cells, because of AFP has a complex molecular structure. AFP not only can promote the proliferation of hepatoma cells, but also can inhibit the immune response in liver cancer patients. Recently, documents showed that AFP has a capability to impair the function of dentritic cells(DCs), and AFP could induce DCs to death. AFP restrain DCs transform to matured antigen presenting cell through regulating the phenotype molecule express in the membrane of DCs, and AFP also influence the expression of tumor necrosis factor family and its receptor in lymphocytes or in hepatoma cells, AFP also could inhibit the activity of caspase in tumor cells, possesses these effects of AFP result in the hepatoma cells escape the immune surveillance.

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Quality assurance of EBCT images is especially important in clinic. Factors influencing the quality of images are so variable and complex that comprehensive consideration should be paid to them. The analyses and researches for such factors as surrounding background, machine's inherent property and scanning parameters are made separately.