Optimizing cecal views during colonoscopy using patient position change.

BACKGROUND: Patient positioning has been found to be a simple technique to improve luminal distention and visualization during colonoscopy. This study examined which position provided the cleanest image of the cecum using the Boston Bowel Prep Scale (BBPS) and the best view of the cecum overall as ranked by blinded assessors. METHODS: A sample of 90 sets of cecal images were obtained from patients undergoing a non-urgent colonoscopy. Each set included cecal images of patients while lying in three positions-right lateral decubitus, left lateral decubitus, and supine. Two authors reviewed these sets of images and excluded those that were unclear. A third author, blinded to the position, selected the final 33 sets of images. Two experienced endoscopists completed a blinded survey of each image set. They used the BBPS to assess and score each image as the primary outcome measure. The endoscopists also ranked each image set in terms of the best overall view of the cecum. Data were collected using Qualtrics software. Nonparametric tests were used to analyze the data using SPSS software (v.25). A p-value of ≤ 0.05 was considered significant. RESULTS: The BBPS showed a significant difference between patient positions when tested by Kruskal-Wallis. Subsequent Mann Whitney U tests indicated that the right lateral decubitus position was ranked higher than left lateral decubitus or supine positions. There was no significant difference in the left and supine positions. Cohen's Kappa suggested moderate agreement between raters. The raters also favored the right lateral position over the other positions when assessing overall image preference displaying the cecum. CONCLUSION: These results indicate that positioning patients in the right lateral decubitus position provides the best view of the cecum during colonoscopy.

A randomized controlled trial comparing right and left lateral decubitus starting position on outcomes in colonoscopy.

BACKGROUND: Patient positioning in colonoscopy has been proposed as a simple and inexpensive technique to increase luminal distention and improve navigation through the large bowel. We sought to determine if the right lateral (RL) starting position compared to the standard left lateral (LL) starting position could improve outcomes in colonoscopy. METHODS: We conducted a randomized controlled trial of 185 patients who were undergoing an elective colonoscopy. Patients were randomized to either a right lateral decubitus starting position or a left lateral decubitus starting position and the primary outcome measure was cecal intubation time. Secondary outcome measures included cecal intubation rate, patient discomfort, and sedation dosage. All colonoscopists who had successfully completed a colonoscopy skills improvement course were included in the trial. A sample size was calculated prior to the start of the study and outcomes were analyzed using univariate and multiple regression analyses. RESULTS: A total of 94 patients were randomized to RL starting position and 91 patients were randomized to LL starting position. No difference was found in time to cecal intubation comparing the RL starting position (542.6 s, SD 360.7 s) to LL starting position (497.85 s, SD 288.3 s) (p = 0.354). Variables associated with prolonged cecal intubation time included female gender, General Surgery specialty, less than 5 years of endoscopist experience, a high patient discomfort score, amount of water used, and number of position changes required to reach the cecum. There was no difference in any of the secondary outcome measures aside from the amount of midazolam used, with more midazolam used for patients starting in the right lateral decubitus position. CONCLUSION: This study failed to show an association between cecal intubation time and patient position comparing right and left lateral starting position.

AID, APOBEC3A and APOBEC3B efficiently deaminate deoxycytidines neighboring DNA damage induced by oxidation or alkylation.

BACKGROUND: AID/APOBEC3 (A3) enzymes instigate genomic mutations that are involved in immunity and cancer. Although they can deaminate any deoxycytidine (dC) to deoxyuridine (dU), each family member has a signature preference determined by nucleotides surrounding the target dC. This WRC (W = A/T, R = A/G) and YC (Y = T/C) hotspot preference is established for AID and A3A/A3B, respectively. Base alkylation and oxidation are two of the most common types of DNA damage induced environmentally or by chemotherapy. Here we examined the activity of AID, A3A and A3B on dCs neighboring such damaged bases. METHODS: Substrates were designed to contain target dCs either in normal WRC/YC hotspots, or in oxidized/alkylated DNA motifs. AID, A3A and A3B were purified and deamination kinetics of each were compared between substrates containing damaged vs. normal motifs. RESULTS: All three enzymes efficiently deaminated dC when common damaged bases were present in the -2 or -1 positions. Strikingly, some damaged motifs supported comparable or higher catalytic efficiencies by AID, A3A and A3B than the WRC/YC motifs which are their most favored normal sequences. Based on the resolved interactions of AID, A3A and A3B with DNA, we modeled interactions with alkylated or oxidized bases. Corroborating the enzyme assay data, the surface regions that recognize normal bases are predicted to also interact robustly with oxidized and alkylated bases. CONCLUSIONS: AID, A3A and A3B can efficiently recognize and deaminate dC whose neighbouring nucleotides are damaged. GENERAL SIGNIFICANCE: Beyond AID/A3s initiating DNA damage, some forms of pre-existing damaged DNA can constitute favored targets of AID/A3s if encountered.