Quantitative study on appearance of microvessels in spectral endoscopic imaging.

Increase in abnormal microvessels in the superficial mucosa is often relevant to diagnostic findings of neoplasia in digestive endoscopy; hence, observation of superficial vasculature is crucial for cancer diagnosis. To enhance the appearance of such vessels, several spectral endoscopic imaging techniques have been developed, such as narrow-band imaging and blue laser imaging. Both techniques exploit narrow-band blue light for the enhancement. The emergence of such spectral imaging techniques has increased the importance of understanding the relation of the light wavelength to the appearance of superficial vasculature, and thus a new method is desired for quantitative analysis of vessel visibility in relation to the actual structure in the tissue. Here, we developed microvessel-simulating phantoms that allowed quantitative evaluation of the appearance of 15-µm-thick vessels. We investigated the relation between the vascular contrast and light wavelength by the phantom measurements and also verified it in experiments with swine, where the endoscopically observed vascular contrast was investigated together with its real vascular depth and diameter obtained by microscopic observation of fluorescence-labeled vessels. Our study indicates that changing the spectral property even in the wavelength range of blue light may allow selective enhancement of the vascular depth for clinical use.

Interlaboratory validation of the modified murine local lymph node assay based on adenosine triphosphate measurement.

INTRODUCTION: The murine local lymph node assay (LLNA) is a well-established alternative to the guinea pig maximization test (GPMT) or Buehler test (BT) for the assessment of the skin sensitizing ability of drugs and chemicals. Daicel Chemical Industries Ltd. has developed a modified LLNA based on the adenosine triphosphate (ATP) content (LLNA-DA). We conducted 2 interlaboratory validation studies to evaluate the reliability and relevance of LLNA-DA. METHODS: The experiment involved 17 laboratories, wherein 14 chemicals were examined under blinded conditions. In the first study, 3 chemicals were examined in 10 laboratories and the remaining 9 were examined in 3 laboratories. In the second study, 1 chemical was examined in 7 laboratories and the remaining 4 chemicals were examined in 4 laboratories. The data were expressed as the ATP content for each chemical-treated group, and the stimulation index (SI) for each chemical-treated group was determined as the increase in the ATP content relative to the concurrent vehicle control group. An SI of 3 was set as the cut-off value for exhibiting skin sensitization activity. RESULTS: The results of the first study obtained in the experiments conducted for the 3 chemicals that were examined in all the 10 laboratories and for 5 of the remaining 9 chemicals were sufficiently consistent with small variations in their SI values. The sensitivity, specificity, and accuracy of LLNA-DA against those of GPMT/BT were 7/8 (87.5%), 3/3 (100%), and 10/11 (90.9%), respectively. In the second study, all the 5 chemicals studied demonstrated acceptably small interlaboratory variations. DISCUSSION: In the first study, a large variation was observed for 2 chemicals; in the second study, this variation was small. It was attributed to the application of dimethylsulfoxide as the solvent for the metallic salts. In conclusion, these 2 studies provide good evidence for the reliability of the LLNA-DA.