BACKGROUND:Previous studies show that the fracture resistant force of endodonticaly treated teeth can be improved by post. But this idea has been controversial in recent years. Many scholars believe that the root canal preparation might weaken dental root the post increases the risk of tooth fracture. OBJECTIVE: To evaluate the fracture resistance ability of severe wedge-shaped-defect premolar to oblique loading, which was restored with fiber reinforced composite posts by different therapy methods. METHODS:A total of 50 human maxilary premolars were randomly divided into five groups, with ten teeth in each group. They were given folowing treatments: Group A: 10 untreated premolars; Rest 40 premolars of Groups B, C, D and E were prepared 1/3 bucco-lingual distance for artificial severe wedge-shaped defects at the buccal cervix. Group B: untreated severe wedge-shaped defects premolars; Group C: severe wedge-shaped defects premolars were endodonticaly treated, remaining dentin over hang above the wedge shaped defect, LuxaPost posts reinforced in buccal canal and lingual canal, LuxaCore composite resin restored dentin defect; Group D: severe wedge-shaped defects premolars were endodonticaly treated, LuxaPost posts reinforced in buccal canal and lingual canal, LuxaCore composite resin restored dentin defect, and then covered with ful metal crown; Group E: severe wedge-shaped defects premolars were endodonticaly treated, removing dentin over hang above the wedge shaped defect, LuxaPost posts reinforced in buccal canal and lingual canal, restored with LuxaCore composite resin, and then covered with ful metal crown. Fracture resistance of each specimen was measured in each group. RESULTS AND CONCLUSION: The fracture strength of each group were Group A (1 002.69±147.62) N, Group B (439.28±66.34) N, Group C (958.30±101.23) N, Group D (1 207.09±143.48) N, and Group E (1 056.44±139.30) N. Group D had the highest fracture strength (P < 0.01), while Group B had the lowest fracture strength (P < 0.01). There were no significant difference among the fracture strength of Group A, Group C and Group E. Our findings indicated that the fracture resistance of the severe wedge-shaped defected premolar can be improved by fiber reinforced composite post and dentin above wedge shaped defect remained.

The clustered regularly interspaced short palindrome repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) system is a versatile genome editing tool with high efficiency. A guide sequence of 20 nucleotides (nt) is commonly used in application of CRISPR/Cas9; however, the relationship between the length of the guide sequence and the efficiency of CRISPR/Cas9 in porcine cells is still not clear. To illustrate this issue, guide RNAs of different lengths targeting the EGFP gene were designed. Specifically, guide RNAs of 17 nt or longer were sufficient to direct the Cas9 protein to cleave target DNA sequences, while 15 nt or shorter guide RNAs had loss-of-function. Full-length guide RNAs complemented with mismatches also showed loss-of-function. When the shortened guide RNA and target DNA heteroduplex (gRNA:DNA heteroduplex) was blocked by mismatch, the CRISPR/Cas9 would be interfered with. These results suggested the length of the gRNA:DNA heteroduplex was a key factor for maintaining high efficiency of the CRISPR/Cas9 system rather than weak bonding between shortened guide RNA and Cas9 in porcine cells.
Base Sequence ; Complement System Proteins ; CRISPR-Cas Systems ; DNA ; Genome ; Nucleotides ; RNA, Guide ; Swine

Objective:To investigate the clinical application of carbon nanoparticles mapping lymph nodes in curative resection for colorectal carcinoma.Methods:Patients diagnosed with colorectal cancer before operation and undergoing radical surgery with intact postoperative pathological data in the Sixth Affiliated Hospital, Sun Yat-sen University from March 2016 to March 2018 were included in this retrospective case-control study. Those who were diagnosed with ileus, recurrent carcinoma or underwent emergency operation were excluded. A total of 1421 cases were included, with 156 cases in the carbon nanoparticles mapping group and 1265 cases in the control group. Using 1∶3 case control matching based on gender, weight, TNM staging and neoadjuvant chemotherapy, 145 and 435 cases were finally recruited in the carbon nanoparticles mapping group and control group, respectively. Patients in the carbon nanoparticles mapping group underwent preoperative colonoscopy with carbon nanoparticles submucosal injection 2.4 (1.0 - 14.0) days before operation. Carbon nanoparticles of 0.25 ml was injected at 4 points (3, 6, 9 and 12 o'clock each) 0.5-1.0 cm around the tumor. The number of eliminated lymph node, number of positive lymph node and positive rate between the two groups were compared, and the number of eliminated lymph node in different subgroups of T stage, N stage, TNM stage and neoadjuvant chemotherapy was analyzed and compared.Results:After case control matching, total number of eliminated lymph nodes in the carbon nanoparticles mapping group was significantly higher than that in the control group (22.2±11.2 vs. 19.0±9.5, t=3.025, P=0.003). However, no statistically significant differences were found in the number of positive lymph node and lymph node positive rate between two groups (all P>0.05). Subgroup analysis showed that as compared to the control group, total number of eliminated lymph nodes in the carbon nanoparticles mapping group was significantly higher in T3 stage subgroup (median: 22 vs. 18, Z=2.435, P=0.015), N0 stage subgroup (median: 20.5 vs. 17.5, Z=2.772, P=0.006), TNM II stage subgroup (median: 23.5 vs. 19.0, Z=2.654, P=0.008) and neoadjuvant chemotherapy (median: 22.5 vs. 13.0, Z=3.287, P=0.001), while compared to the control group, the number of positive lymph node (median: 4.0 vs. 6.5, Z=-2.530, P=0.011) and the lymph node metastasis degree (median: 16% vs. 31%, Z=-2.862, P=0.004) were lower in the carbon nanoparticles mapping group in N2 subgroup. Conclusion:Carbon nanoparticles mapping lymph nodes can effectively enhance the number of eliminated lymph nodes in curative resection for colorectal cancer.

Objective:To investigate the clinical application of carbon nanoparticles mapping lymph nodes in curative resection for colorectal carcinoma.Methods:Patients diagnosed with colorectal cancer before operation and undergoing radical surgery with intact postoperative pathological data in the Sixth Affiliated Hospital, Sun Yat-sen University from March 2016 to March 2018 were included in this retrospective case-control study. Those who were diagnosed with ileus, recurrent carcinoma or underwent emergency operation were excluded. A total of 1421 cases were included, with 156 cases in the carbon nanoparticles mapping group and 1265 cases in the control group. Using 1∶3 case control matching based on gender, weight, TNM staging and neoadjuvant chemotherapy, 145 and 435 cases were finally recruited in the carbon nanoparticles mapping group and control group, respectively. Patients in the carbon nanoparticles mapping group underwent preoperative colonoscopy with carbon nanoparticles submucosal injection 2.4 (1.0 - 14.0) days before operation. Carbon nanoparticles of 0.25 ml was injected at 4 points (3, 6, 9 and 12 o'clock each) 0.5-1.0 cm around the tumor. The number of eliminated lymph node, number of positive lymph node and positive rate between the two groups were compared, and the number of eliminated lymph node in different subgroups of T stage, N stage, TNM stage and neoadjuvant chemotherapy was analyzed and compared.Results:After case control matching, total number of eliminated lymph nodes in the carbon nanoparticles mapping group was significantly higher than that in the control group (22.2±11.2 vs. 19.0±9.5, t=3.025, P=0.003). However, no statistically significant differences were found in the number of positive lymph node and lymph node positive rate between two groups (all P>0.05). Subgroup analysis showed that as compared to the control group, total number of eliminated lymph nodes in the carbon nanoparticles mapping group was significantly higher in T3 stage subgroup (median: 22 vs. 18, Z=2.435, P=0.015), N0 stage subgroup (median: 20.5 vs. 17.5, Z=2.772, P=0.006), TNM II stage subgroup (median: 23.5 vs. 19.0, Z=2.654, P=0.008) and neoadjuvant chemotherapy (median: 22.5 vs. 13.0, Z=3.287, P=0.001), while compared to the control group, the number of positive lymph node (median: 4.0 vs. 6.5, Z=-2.530, P=0.011) and the lymph node metastasis degree (median: 16% vs. 31%, Z=-2.862, P=0.004) were lower in the carbon nanoparticles mapping group in N2 subgroup. Conclusion:Carbon nanoparticles mapping lymph nodes can effectively enhance the number of eliminated lymph nodes in curative resection for colorectal cancer.