Objective To find a novel operative modality with sphincter preservation in the treatment of middle and low rectal carcinoma. Methods Pull through lower resection was performed on 28 rectal cancer patients. The distance between the anal verge and the lower margin of the tumor was 6～8cm(20 patients) or 8～10cm(8 patients), including 8 patients in Dukes A stage, 16 Dukes B and 4 Dukes C. The resected line from tumor distal margin was 2cm, 3cm, and 4cm, respectively. Results There was no operative death, anastomotic fistula or anastomotic stenosis in these cases. Mean follow up period was 30 months. Local recurrence was found in two cases (7.1%) 18 months after the operation, and 26 cases were cancer free till the end of the follow up. Defecation was satisfactorily controlled 8～12 weeks after the operation. Conclusions Pull through Welch procedure could meet the criterion of the radical resection of rectal carcinoma,and keep the internal and external sphincter muscles intact in the superior lower anterior resection. The normal defecationcan can maintain after the operation due to the preservation of internal and external sphincter muscles.

Objective To evaluate target-volume coverage and organ at risk (OAR) protection achieved with conventional radiotherapy (CRT), three dimensional eonformal radiotherapy (3DCRT) , and intensity-modulated radiotherapy(IMRT) through dosimetric comparison in patients with cervical cancer after hysterectomy. Methods The planning CT scans of 10 patients treated with pelvic radiation after hysterectomy for cervical cancer were used to generate CRT,3DCRT and IMRT plans for this study. Clinical target volume(CTV) was contoured on the individual axial CT slices of every patient. The CTV was then uniformly expanded by 1.0 cm to create the planning target volume (PTV). The small bowel, rectum, bladder, bone marrow, ovaries, and femoral heads were outlined for the organ at risk (OAR) evaluation. The CRT ,3DCRT and IMRT plans were generated using commercial planning software. CRT plan was prescribed to deliver 45 Gy to the reference point,while IMRT and 3DCRT plans were 45 Gy to 95% of the FFV. Isodose line and dose volume histograms(DVH) were used to evaluate the dose distribution in CTV and OAR. Results For 10 patients, the average volume of CTV receiving the prescribed dose of CRT was significantly lower than 3DCRT( Q = 8.27,P ＜ 0.01 ) and IMRT( Q = 8.37, P ＜ 0.01 ), respectively. Comparing with the CRT plan,the 3DCRT and IMRT plans notably reduced the volume of bowel at 30 and 45 Gy levels. The IMRT plan significantly spared rectum and bladder at 30 and 45 Gy levels comparing with the CRT ( P ＜ 0.01 ) and 3DCRT( P ＜ 0.05 ) plans,while the 3DCRT plan significantly spared rectum and bladder at 45 Gy level comparing with the CRT( P ＜0.01 ) plans. For 4 patients with ovarian transposition, the average doses of ovary over 3 Gy were 2 patients with the 3DCRT and IMRT plans, and 2 with all three plans. Conclusions IMRT and 3DCRT are superior to CRT in improving dose coverage of target volume and sparing of OAR ,while IMRT being the best. The superiority of IMRT and 3DCRT is obvious in sparing bone marrow at high dose levels. IMRT,3DCRT and CRT could not spare the transposed ovary effectively.

Objective To investigate the relationship between dose-volume histogram (DVH) parameters and the late side effects (LSE) of the rectum in external-beam radiotherapy combined with computed tomography (CT)-based brachytherapy for locally advanced cervical cancer.Methods From 2008 to 2011,18 patients with stage ⅡB-ⅢB cervical cancer received external-beam radiotherapy and CTbased brachytherapy.The DVH parameters of high-risk clinical target volume (HR CTV) D90,point A dose,and D1 cm3 and D2 cm3 of the rectum and bladder were calculated by Oncentra HDR treatment planning system.Survival outcomes were followed up and rectal LSE were evaluated by RTOG/EORTC grades.Results The point A dose and HR CTV D90 were (93.0 ± 5.5) Gy and (73.6 ± 11.9) Gy,respectively.The median follow-up was 26 months.No recurrence was found during follow-up.Eight patients had mild and moderate rectal LSE,and their rectum D2 cm3 and D1 cm3 were significantly higher than those of patients without mild and moderate rectal LSE (D2 cm3:(87.4 ± 3.8) Gy vs.(75.8 ± 7.4) Gy,P =0.004 ; D1 cm3:(96.4±6.6) Gy vs.(80.5± 7.1) Gy,P=0.001).Conclusions HR CTV D90 in CT-based brachytherapy for locally advanced cervical cancer might be lower than that in the MRI-based plan.Rectum D2 cm3 is recommended to be less than 75 Gy.

Objective To investigate the relationship between the channel design of tandem-andovoid (T&O) applicator and the doses to organs at risk (OARs) and target volume in three-dimensional brachytherapy for advanced cervical carcinoma.Methods The data on 15 patients with advanced cervical carcinoma treated with three-dimensional brachytherapy in our hospital from 2015 to 2016 were collected,and 30 randomly selected high-dose-rate titanium T&O plans were retrospectively studied.CT-guided,conformal brachytherapy plans were generated.To simulate T&O applicator,the tandem applicator was virtually compared with the T&O plans with the target volume and OARs remaining unchanged.The DVH parameters of the rectum,bladder,and sigmoid were compared using the paired t test.Results For T&O plans and tandem applicator plans,the mean D2cc of the rectum was 387.8±96.8 cGy and 340.8±88.1 cGy,respectively;the mean D2cc of the bladder was 443.2± 87.5 cGy and 719.4± 243.0 cGy,respectively;the mean D2cc of the sigmoid was 330.3±88.8 cGy and 383.1±105.6 cGy,respectively.In the T&O plans,the doses to the rectum,bladder,and sigmoid were within the limits (rectum:D2cc ≤ 500 cGy;bladder:D2cc ≤ 550 cGy;sigmoid:D2c ≤ 500 cGy),while D2cc of the bladder and sigmoid was higher or partially higher than the limits.T&O plans showed a significant reduction in bladder D2cc and sigmoid D2cc compared with the tandem applicator plans (all P＜0.05).Conclusions Compared with tandem applicator plans,plans using T&O applicator provide significant sparing of bladder and sigmoid tissues in three-dimensional brachytherapy for cervical carcinoma,but the toxicities require further investigation.

To investigate the RNA interference (RNAi) effect induced by vector-derived small interfering RNA (siRNA) targeting the three gatekeeper genes (Rad52, Ku70, Ku80) and screen the more effective target sites from candidates for further research, by using siRNA design tools online, we selected 2 candidate sequences directed to every gatekeeper gene. According to the sequences, six vector-derived siRNAs (denoted psiRNA1-6) and one mocking psiRNA7 were constructed. Among them, psiRNA1 and psiRNA2 targeted Rad52, psiRNA3 and psiRNA4 to Ku70, psiRNA5 and psiRNA6 to Ku80. The mocking psiRNA7 was used as control. After sequence identification, the seven plasmids were transfected into HepG2 cell line. siRNA-induced silencing of gatekeeper genes was determined by using RT-PCR at RNA level and Western Blot at protein level. The results showed that the six plasmids specifically targeting the coding region of gatekeeper genes were successfully designed and constructed. To some extent, the six plasmids could reduce the expression of target gene. Comparatively, the plasmid-derived siRNA psiRNA1, psiRNA4 and psiRNA5 were more effective than their counterparts. The results suggest that the gene silencing efficiency of siRNA is different, depending on their targeted region, and siRNA may provide us with practical tools for further study on the three gatekeeper genes, i.e. Rad52, Ku70, Ku80.

To investigate the RNA interference (RNAi) effect induced by vector-derived small interfering RNA (siRNA) targeting the three gatekeeper genes (Rad52, Ku70, Ku80) and screen the more effective target sites from candidates for further research, by using siRNA design tools online,we selected 2 candidate sequences directed to every gatekeeper gene. According to the sequences, six vector-derived siRNAs (denoted psiRNA1-6) and one mocking psiRNA7 were constructed. Among them, psiRNA1 and psiRNA2 targeted Rad52, psiRNA3 and psiRNA4 to Ku70, psiRNA5 and psiRNA6 to Ku80. The mocking psiRNA7 was used as control. After sequence identification, the seven plasmids were transfected into HepG2 cell line. siRNA-induced silencing of gatekeeper genes was determined by using RT-PCR at RNA level and Western Blot at protein level. The results showed that the six plasmids specifically targeting the coding region of gatekeeper genes were successfully designed and constructed. To some extent, the six plasmids could reduce the expression of target gene.Comparatively, the plasmid-derived siRNA psiRNA1, psiRNA4 and psiRNA5 were more effective than their counterparts. The results suggest that the gene silencing efficiency of siRNA is different,depending on their targeted region, and siRNA may provide us with practical tools for further study on the three gatekeeper genes, i.e. Rad52, Ku70, Ku80.

In order to screen potential mRNA locations of P gene in which targeting siRNAs can effectively inhibit HBV expression, 5 recombinant plasmids containing 4 targeting-specific siRNA fragments and a control were prepared and transfected into 2.2.15 cells respectively. The expression levels of HBx mRNA, HBs mRNA and HBc mRNA were detected by RT-PCR. The concentrations of the hepatitis B virus antigens, including HBsAg and HBeAg harvested from the culture supernatant of transfected 2.2.15 cells, were measured by ELISA. X protein was tested by Western blot. The results showed that four siRNAs against distinct mRNA locations of HBV polymerse gene had different inhibitory effects on their targeted mRNA. The plasmid-derived psiRNAl and psiRNA2 could effectively inhibit the transcription and translation of HBs gene, whereas the inhibitory efficiency of psiRNA3, psiRNA4 for HBe gene was much higher than that of psiRNA1 and psiRNA2. In comparison to the rest of psiRNAs in this study, psiRNA4 was the most effective to suppress the transcription and translation of HBx. It is suggested that siRNA can be considered as a powerful therapeutic agent for reducing HBV expression. The siRNAs against HBV polymerase are effective largely depending on the location of targeted sites. To enhance inhibitory efficiency, hunting for high effective target in polymerase gene is necessary and feasible.