Near-infrared fluorescence tattooing: a new approach for endoscopic marking of tumors in minimally invasive colorectal surgery using a persistent near-infrared marker.

INTRODUCTION: Intraoperative accurate localization of tumors in the lower gastrointestinal tract is essential to ensure oncologic radicality. In minimally invasive colon surgery, tactile identification of tumors is challenging due to diminished or absent haptics. In clinical practice, preoperative endoscopic application of a blue dye (ink) to the tumor site has become the standard for marking and identification of tumors in the colon. However, this method has the major limitation that accidental intraperitoneal spillage of the dye can significantly complicate the identification of anatomical structures and surgical planes. In this work, we describe a new approach of NIR fluorescent tattooing using a near-infrared (NIR) fluorescent marker instead of a blue dye (ink) for endoscopic tattooing. METHODS: AFS81x is a newly developed NIR fluorescent marker. In an experimental study with four domestic pigs, the newly developed NIR fluorescent marker (AFS81x) was used for endoscopic tattooing of the colon. 7-12 endoscopic submucosal injections of AFS81x were placed per animal in the colon. On day 0, day 1, and day 10 after endoscopic tattooing with AFS81x, the visualization of the fluorescent markings in the colon was evaluated during laparoscopic surgery by two surgeons and photographically documented. RESULTS: The detection rate of the NIR fluorescent tattoos at day 0, day 1, and day 10 after endoscopic tattooing was 100%. Recognizability of anatomical structures during laparoscopy was not affected in any of the markings, as the markings were not visible in the white light channel of the laparoscope, but only in the NIR channel or in the overlay of the white light and the NIR channel of the laparoscope. The brightness, the sharpness, and size of the endoscopic tattoos did not change significantly on day 1 and day 10, but remained almost identical compared to day 0. CONCLUSION: The new approach of endoscopic NIR fluorescence tattooing using the newly developed NIR fluorescence marker AFS81x enables stable marking of colonic sites over a long period of at least 10 days without compromising the recognizability of anatomical structures and surgical planes in any way.

Choice of test stimulus matters for pitch matching performance: Comparison between pure tone and narrow band noise.

Chronic tinnitus, a symptom of high prevalence, is a persistent hearing sensation in the absence of an external sound source. Recent electrophysiological studies indicate that tinnitus generation is to a high degree the result of maladaptive plasticity in the central auditory pathway. The pitch of the tinnitus sensation can be assessed by performing a pitch matching procedure. In the most frequent "tonal tinnitus" type pure tones are used as test stimuli. However, in the case of tonal tinnitus not a single malfunctioning neuron, but rather a population of neighbouring neurons is involved in the generation process of tinnitus and patients typically perceive their tinnitus as a sound having a prominent centre frequency with some spectral extent. Thus, the question arises, why not to use narrow band noise (NBN) instead of pure tones as test stimuli in pitch matching procedures? To investigate this, we first evaluated the pitch matching performance of healthy subjects. In a recursive two alternative choice testing, driven by a computer based automated procedure, the subjects were asked to match the pitch of two sounds. In a crosswise design, NBNs and pure tones were used both as target and as test stimuli. We were able to show that across all four possible combinations the pitch matching performance was least favourable when a sinusoidal sound had to be matched to an NBN target. Even though matching two sinusoidal sounds results in the lowest error, considering that the tinnitus percept typically includes some spectral extent, an NBN should be preferably used as a test stimulus against a pure tone.

Use of sequence variation in three highly variable regions of the mitochondrial DNA for the discrimination of allogeneic platelets.

BACKGROUND: Human mitochondrial DNA (mtDNA) polymorphisms can be used to detect allogeneic transfused platelets. To increase the number of informative polymorphisms we investigated three hypervariable regions (HVR1, HVR2, and HVR3) within the displacement loop (D-loop) region of the mtDNA. STUDY DESIGN AND METHODS: mtDNA was obtained from 119 unrelated blood donors. Forward and reverse primers were designed and conditions optimized to amplify and sequence the template mtDNA by dye terminator cycle sequencing. RESULTS: We established a sequencing protocol for all three HVRs of the mtDNA. Polymorphic sites were found in all three regions: 66 in HVR1, 44 in HVR2, and 18 in HVR3. Combining the sequence information of HVR1, -2, and -3 resulted in 105 different genotypes of which 95 were unique. We were able to discriminate between two randomly chosen individuals with a random match probability of 1.2 percent. CONCLUSION: The D-loop region of mtDNA contains a wealth of informative molecular markers for chimerism and survival studies after transfusions of cellular blood components.