[Impact of polyamidoamine dendrimer liposome on the cellular uptake and cytotoxicity of colonic cancer cells].

OBJECTIVE: To evaluate the effects of polyamidoamine dendrimer (PAMAM) liposome as gene carriers on the cellular uptake and its cytotoxicity in colonic cancer cell. METHODS: The liposome modified PAMAM was synthesized with liposome and polyamidoamine dendrimer. Plasmid PEGFP-N1 was mixed with the liposome-modified PAMAM or unmodified PAMAM to form nanoparticle complexes. The shape and size of the nanoparticle complexes were observed by transmission electron microscope and the zeta potential was measured by analytical tool. The encapsulating efficiency was determined by ultraviolet spectrophotometer in centrifuging method. After the cell lines SW620 (colonic cancer cell), MCF-7 (breast cancer cell), ECV304 (vascular endothelial cell) were transfected by the two kinds of PAMAM nanoparticle complexes, the flow cytometry was used to determine the uptake of enhanced green fluorescent protein (EGFP) gene. The cytotoxicity of PAMAM liposome nanoparticles and PAMAM nanoparticles was evaluated by MTT assay. RESULTS: The diameter of liposome modified PAMAM complex was (192 ± 16) nm, and that of PAMAM complex was (189 ± 19) nm (P > 0.05); and the zeta potential of liposome modified PAMAM complex was higher than that of PAMAM complex [(42 ± 7) mV vs. (32 ± 7) mV, P < 0.05]. There was no significant difference in envelopment rate between the two groups [(82 ± 7)% vs. (84 ± 6)%, P > 0.05]. After the colonic cancer cell line SW620 was transfected with the two kinds of PAMAM nanoparticle complexes, the cellular uptake of the cells with the liposome-modified PAMAM complex was significantly higher than that of the cell with PAMAM complex (P < 0.05). The cellular survival rate of the cell lines with liposome-modified PAMAM complex was significantly higher than that of cell lines with PAMAM complex (P < 0.05). CONCLUSION: The liposome modified PAMAM can improve gene transfection efficiency and suppress its cytotoxicity.

[Manufacture and application of laparoscopic extraperitoneal sigmoid colostomy].

OBJECTIVE: To investigate the safety and feasibility of laparoscopic extraperitoneal sigmoid colostomy. METHODS: Thirty-six patients with low rectal cancer undergoing laproscopic abdominoperineal resection from July 2011 to July 2012 were prospectively enrolled in the study and randomly divided into extraperitoneal colostomy group(EPC, n=18) and internal peritoneal colostomy group(IPC, n=18). Follow-up period was 4-16 (median, 7) months and postoperative complications were compared between two groups. RESULTS: One case in EPC group was converted to IPC because of poor blood supply of the proximal sigmoid, who was eliminated from the subsequent analysis. Compared with the IPC group, the surgery time was longer in EPC group [(25.3±8.5) min vs. (14.7±6.4) min], while the difference was not statistically significant(P>0.05). Each group had 1 case of stoma ischemia, who both received the colostomy reconstructive surgery. The incidence of stoma edema was significantly higher in EPC group[35.3%(6/17) vs. 0, P<0.05). The early postoperative complications rate did not significantly different between the two groups[58.8%(10/17) vs. 27.8%(5/18), P>0.05]. The late postoperative complications rate was 22.2%(4/18) in IPC group, including 1 case of stoma prolapse, 1 case of stoma stenosis and 2 cases of parastomal hernia. No later postoperative complication occurred in EPC group. CONCLUSION: Extraperitoneal sigmoid colostomy is an easy and safe procedure with lower late complications as compared to internal peritoneal sigmoid colostomy.

[Study on accuracy of endoscopic polyp size measurement by disposable graduated biopsy forceps].

OBJECTIVE: To study the accuracy of endoscopic polyp size measurement by disposable graduated biopsy forceps (DGBF). METHODS: Accurate gradation of 1 mm was made in the wire of disposable graduated biopsy forceps, which was used to measure the size of tumors under endoscopy. Fifty-eight polyps from 43 patients underwent endoscopy in our department from May to June 2013 were enrolled. Size of polyp was measured and compared among DGBF, routine estimation and direct measurement after resection. The accuracy of polyp size measurement was investigated by four colonoscopists who had finished at least 2000 procedures of colonoscopy. RESULTS: The mean diameter of post-polypectomy measurement was (1.02±0.84) cm. Diameter was less than 1 cm in 36 polyps, 1 to 2 cm in 15, and over 2 cm in 7. The mean diameter of visual estimation was (1.29±1.07) cm, and the difference was significant as compared with actual size (P=0.000). The mean diameter measured by DGBF was (1.02±0.82) cm, and the difference was not significant as compared with actual size (P=0.775). The ratio of visual estimation to actual size was 1.29±0.31, and DGBF estimation to actual size was 1.02±0.11 with significant difference (P=0.000). The accurate rate of DGBF in estimating polyp size was 77.6% (45/58), which was obviously higher as compared to visual estimation [19.0% (11/58), P=0.000]. CONCLUSION: The accuracy of DGBF as a scale in the estimation of poly size increases as compared to visual estimation.

[Distribution characteristics of colorectal neoplasm in 4450 patients and implication for colorectal cancer screening].

OBJECTIVE: To study the distribution characteristics of colorectal neoplasm and evaluate the implication for colorectal cancer screening. METHODS: A total of 17,939 colonoscopies were performed in the National Center of Colorectal Surgery between October 2004 and June 2009. Characteristics of colorectal neoplasm including anatomical distribution, sex, and age were investigated. RESULTS: Colorectal neoplasm was found in 24.8% (4450/17,939) of the patients during colonoscopy, including adenomatous polyp (n=3410, 19.0%) and adenocarcinoma (n=1040, 5.8%). The prevalence of colorectal neoplasm was higher in male and significantly increased in patients older than 40 years. 63.3% of the lesions located at the distal colon (sigmoid colon and rectum) and 36.7% at the proximal colon (36.7%). In patients with adenomatous polyp, 52.8% (1802/3410) of the lesions were at the distal colon, 30.8% (1049/3410) at the proximal colon, and 16.4% (559/3410) at both distal and proximal colon. In patients with carcinoma (n=1040), 921 (88.6%) lesions located at the distal colon, 118 (11.3%) at the proximal colon, and 1 (0.1%) at both segments. CONCLUSION: Sigmoidoscopy is inadequate for colorectal cancer screening as compared to colonoscopy.

[Indications for colonoscopy examination and its disease distribution: a report of 5690 cases].

OBJECTIVE: To explore the indications for colonoscopy examination and the distribution of diagnostic diseases. METHOD: From Jan. 2000 to Dec. 2004, 5960 patients received colonoscopy examination in our colorectal center. The indications for colonoscopy examination and the distribution of its diagnostic diseases were analyzed. RESULTS: There were 3096 males and 2594 females,and the mean age was (52+/-15) years. The reasons for colonoscopy included hemafecia (26.9%), atypical abdominal pain (25.8%), diarrhea or increased frequency of stool (11.1%), anal tenesmus or discomfort (7.6%), constipation (7.0%),mucous or bloody purulent stool (3.0%), intra-rectal mass or abdominal mass on physical examination (0.9%), re- examination after colonoscopic polypectomy (10.9%), re-examination after operation for colorectal cancer(1.5%), simple health examination (2.2%). Colonoscope reached the cecum in 97.7% of the cases,and at least one disease was found in 2283 cases (40.1%). Among them,colorectal cancer accounted for 10.3%, colorectal polyps 19.6%, ulcerative colitis 4.3%, and Crohn's disease 0.5% respectively. CONCLUSION: The indications for colonoscopy are too strict to screen the early stage colorectal cancer. Colonoscopy should be performed in the cases with symptoms such as bloody stool, diarrhea, abdominal pain, constipation, or with colorectal polyps, after operation for colorectal cancer,or as members of hereditary colorectal cancer family.