Nile Blue Can Photosensitize DNA Damage through Electron Transfer

The mechanism of DNA damage photosensitized by Nile blue (NB) was studied using ³²P-5′-end-labeled DNA fragments. NB bound to the DNA strand was possibly intercalated through an electrostatic interaction. Photoirradiated NB caused DNA cleavage at guanine residues when the DNA fragments were treated with piperidine. Consecutive guanines, the underlined G in 5′-<u>G</u>G and 5′-<u>GG</u>G, were selectively damaged through photoinduced electron transfer. The fluorescence lifetime of NB was decreased by guanine-containing DNA sequence, supporting this mechanism. Single guanines were also slightly damaged by photoexcited NB, and DNA photodamage by NB was slightly enhanced in D₂O. These results suggest that the singlet oxygen mechanism also partly contributes to DNA photodamage by NB. DNA damage photosensitized by NB via electron transfer may be an important mechanism in medicinal applications of photosensitizers, such as photodynamic therapy in low oxygen

What Kind of Capsule Endoscope Is Suitable for a Controllable Self-Propelling Capsule Endoscope? Experimental Study Using a Porcine Stomach Model for Clinical Application (with Videos)

<div><p>Background</p><p>We have been developing the Self-Propelling Capsule Endoscope (SPCE) that allows for controllability from outside of the body and real-time observation. What kind of capsule endoscope (CE) is suitable for a controllable SPCE is unclear and a very critical point for clinical application. We compared observing ability of three kinds of SPCEs with different viewing angles and frame rates.</p><p>Methods</p><p>Eleven buttons were sewed in an excised porcine stomach. Four examiners controlled the SPCE using PillCamSB2, -ESO2, and -COLON2 (Given Imaging Ltd., Israel), for 10 minutes each with the aim of detecting as many buttons and examining them as closely as possible. The ability to find lesions was assessed based on the number of detected buttons. The SPCE-performance score (SPS) was used to evaluate the ability to examine the lesions in detail.</p><p>Results</p><p>The SPCE-ESO2, -COLON2, and -SB2 detected 11 [interquartile range (IQR): 0], 10.5 (IQR, 0.5), and 8 (IQR, 1.0) buttons, respectively. The SPCE-ESO2 and -COLON2 had a significantly better ability to detect lesions than the -SB2 (p < 0.05). The SPCE-ESO2, -COLON2, and -SB2 had significantly different SPS values of 22 (IQR, 0), 16.5 (IQR, 1.5), and 14 (IQR, 1.0), respectively (p < 0.05 for all comparisons; SPCE-SB2 vs. -ESO2, -SB2 vs. -COLON2, and -ESO2 vs. -COLON2).</p><p>Conclusions</p><p>PillCamESO2 is most suitable in different three CEs for SPCE for examining lesions in detail of the stomach.</p></div

Driving system for the self-propelling capsule endoscope (SPCE), which uses a magnetic field (New MiniMermaid system).

<p>Driving system for the self-propelling capsule endoscope (SPCE), which uses a magnetic field (New MiniMermaid system).</p

In total, 11 buttons with different colors were sewed to the mucosal side of the porcine stomach model.

<p>The image in the lower right panel is the stomach model, which was opened along the greater curvature after the experiment.</p

(a) The body of a self-propelling capsule endoscope (SPCE). (b) A patient undergoes SPCE examination using the New MiniMermaid system. (c) The SPCE maneuver is conducted by a controller.

<p>(a) The body of a self-propelling capsule endoscope (SPCE). (b) A patient undergoes SPCE examination using the New MiniMermaid system. (c) The SPCE maneuver is conducted by a controller.</p

Examples of the images and their associated self-propelling capsule endoscope-performance scores.

<p>The score is the sum of the points given to each button as follows: 2 points were given if the buttons could be approached and observed closely; 1 point was given if the buttons came into view but could not be approached closely; and no points were given if the buttons could not be detected.</p