Effects of different-intensity laser acupuncture at two adjacent same-meridian acupoints on nitric oxide and soluble guanylate cyclase releases in human.

OBJECTIVES: The aim of this study was to detect the influences of LA at nonacupoint and two adjacent acupoints of pericardium meridian on the releases of NO and sGC in 20 healthy subjects. METHODS: Different intensities (12, 24, 48 mW) of infrared laser were used for irradiating Jianshi (PC5), Ximen (PC4) acupoints and nonacupoint for 20, 40 minutes, respectively. Semi-circular tubes were taped to the skin surface and filled with NO-scavenging compound for 20 minutes to capture NO and sGC, which were measured using spectrophotometry in a blinded fashion. RESULTS: As the increase in the intensity of LA stimulation, the levels of NO releases over acupoints all were significantly increased, NO releases in nonacupoints following the same treatment only changed slightly, sGC amounts were observably enhanced over acupoints, but did not any change in nonacupoint area. Different intensities of LA treatments can sensitively affect the NO and sGC releases over acupoints. This indicated that LA-induced releases of the NO and sGC were specific to acupoints. CONCLUSIONS: This is the first evidence reporting that LA induced significant elevations of NO-sGC releases over acupoints, and the enhanced signal molecules contribute to local circulation, which improves the beneficial effects of the therapy.

Changes in Nitric Oxide Releases of the Contralateral Acupoint during and after Laser Acupuncture at Bilateral Same-Name Acupoints in Human.

OBJECTIVE: The purpose of the study was to examine the effects of laser acupuncture (LA) at right Neiguan (RPC6)/left Neiguan (LPC6) acupoints on the releases of nitric oxide (NO) in the treated and contralateral/nontreated PC6, compared to the nonacupoint control area. METHODS: 24 mW LA at RPC6, LPC6, and nonacupoint in 22 healthy subjects for 40 min: sterilized dialysis tube was taped to the nontreated PC6/nonacupoint during the treatment and immediately taped to the treated and nontreated PC6/nonacupoint after LA removal. NO-scavenging compound was injected into the tube for 40 min to absorb the molecular which was tested by spectrophotometry in a blinded fashion. RESULTS: LA-induced NO releases over PC6 acupoints for the nontreated and treated sides all significantly increased after LA removal, but for the nontreated acupoints they did not change during LA stimulation. LA at RPC6 induced the more release of the NO at contralateral side than stimulating LPC6, but not on nonacupoints. The results suggest that LA-induced NO release over contralateral acupoint and NO release resulting from the lateralized specificity all are different and specific to the acupoint within different time course. CONCLUSIONS: LA-evoked NO release over acupoints could improve the neurogenic, endothelial activity of the vessel wall to further facilitate microcirculation.

Mechanism study of laser cochleostomy-induced early hearing loss in a rat model.

Hearing loss following laser-assisted ear surgery has been reported. However, the mechanism responsible for the hearing loss remains largely speculative. The aim of this study was to investigate the correlation between laser-induced hearing loss and changes in the number of hair cell ribbon synapses and ultrastructure in the cochlea. Laser cochleostomy was performed with a superpulsed carbon dioxide (CO2) laser at 2 and 5 W in Sprague-Dawley rats. Auditory brainstem responses (ABRs) were measured preoperatively and 2 days after surgery. The synapse numbers in apical and middle cochlear turns were quantified. Transmission electron microscopy was employed to further examine the subcellular changes in the cochlea. Click and tonal ABR threshold shifts in both 2 and 5-W groups displayed a frequency-dependent loss within the frequency range measured. Laser cochleostomy induced a significant decrease of synapse numbers in the middle turn in both groups (p < 0.05). Electron microscopy data indicated varying degrees of auditory nerve degeneration in both groups. Auditory nerve degeneration might contribute to laser-caused hearing loss even under low-energy laser cochleostomy. The high-energy laser-induced hearing loss was associated with more reduction of synapse number.

[Effects of laser-assisted cochleostomy on inner hair cell ribbon synapse in rats].

OBJECTIVE: To investigate the effects on ribbon synapse of inner hair cells after superpulsed CO2 laser-assisted cochleostomy in SD rats. METHODS: Eighteen SD rats were randomly divided into laser-assisted surgery groups (2 W group and 5 W group), sham-operated group and control group. Ten of those were performed a cochleostomy using superpulsed CO2 laser with a corresponding power. Auditory brainstem responses (ABR) were measured pre-and postoperatively. The ribbon synapses at apical and middle cochlear turns were observed under laser scanning confocal microscope and then were quantified with 3ds Max software. RESULTS: The postoperative ABR thresholds of the 2 W and 5 W groups were larger than the preoperative case (t = -5.65, P < 0.01; t = -4.97, P < 0.01). The synapse number at the middle turn decreased significantly in 5 W group (F = 17.15, P < 0.01), while no significant changes were noted at the apical turn (P > 0.05). There was no statistical difference in 2 W group (P > 0.05). CONCLUSIONS: The superpulsed CO2 laser-assisted cochleostomy with high-power is accompanied by a synaptic injury, while no obvious effects after the low-power laser surgery, which might be a safe strategy to preform cochleostomy.

[Comparative study of time-correlated temperature and back-scattered light intensity for human Hegu acupoint and non-acupoint tissue irradiated by near-infrared laser].

Characteristics and differences of temperature and back-scattered light intensity in different depths of 0.2, 0.4, 0.6, 0.8 and 1 mm for both human Hegu acupoint and non-acupoint tissue irradiated by 808 nm diode laser at the different power of 15, 25 and 35 mW were studied. The temperature and the back-scattered light intensity in different depths of 0.2, 0.4, 0.6, 0.8 and 1 mm for human Hegu acupoint and non-acupoint tissue were measured by using the infrared thermography and optical coherence tomography. The result shows few differences in the temperature and the back-scattered light intensity of human Hegu acupoint and non-acupoint tissue before irradiation. The temperature and back-scattered light intensity of Hegu acupoint and the non-acupoint after irradiation were significantly higher, and the temperature and back-scattered light intensity of Hegu acupoint significantly were higher than the non-acupoint areas. At 0-40 min after the irradiation, the temperature and back-scattered light intensity of Hegu acupoint and the non-acupoint area will fluctuate and gradually decrease with the passage of time. From the results above, it is clearly seen that Hegu acupoint is different from non-acupoint both in the back-scattered light intensity and temperature after irradiation, and Hegu acupoint is more sensitive to laser irradiation than non-acupoint tissue.

[Low level laser irradiation in the visible spectra induces HeLa cells proliferation].

The aim of this in vitro study was to evaluate the effects of low level laser irradiation on the proliferation of HeLa cells using 405 nm diode laser, 514 nm argon laser, 633 nm He-Ne laser, or 785 nm diode laser, The cells were seeded on 96-well microplates for 24 h in 5% fetal bovine serum containing medium, then irradiated with the laser at dose of 100 and 1 000 J x m(-2), respectively. At the time point of 24, 48, 72 h after irradiation, cell viability was assessed by MTT assay. The results show that 405, 633 and 785 nm laser irradiation induces wavelength-dependent and time-dependent proliferation. 633 nm laser irradiation results in a stimulatory proliferation effect that is most significant, whereas 514 nm laser irradiation produces little increase in cell proliferation. Low level laser irradiation increases cell proliferation in a dose-dependent manner. 1 000 J x m(-2) laser irradiation is more effective in increasing cell proliferation than 100 J x m(-2) laser irradiation using 405 nm diode laser, 633 nm He-Ne laser, or 785 nm diode laser, but not as effective as using 514 nm argon laser.

[In vivo reflectance spectroscopy study of different clearing agents on human skin optical clearing].

The changes of skin tissue reflectance spectroscopy before and after being treated with the optical clearing agents of three different types of optical clearing within the wavelength rang of 400-1 000 nm, and the degree of changes in reflectance spectroscopy of each group skin during 0-60 min at 580 nm in vivo were real-time dynamically researched. The reflectance spectroscopy of skin tissue before and after being dealt by the optical clearing agents of glycerol, glucose and propylene glycol was measured using a USB-4000 fiber spectrophotometer at 0, 10, 20, 30, 40, 50 and 60 min. The results showed that the reflectance spectral intensity was distinctly decreased, but the reflectance was significantly increased gradually with the time prolonged. However, different optical clearing agents have different clearing progress. The relative decrease of reflectance of palm skin tissue before and after being dealt by the optical agents of 40% glycerol, 40% glucose and 40% propylene glycol during 10, 20, 30, 40, 50 and 60 min at the wavelength 580 nm is 5%, 7%, 9%, 10%, 11% and 12%, 9%, 13%, 16%, 19%, 21% and 22%, and 14%, 22%, 29%, 32%, 34% and 35%, respectively. The significant improvement in light transmittance and enhancement of light penetration through tissue was demonstrated for all solutions. The effect and processes of optical clearing of skin tissue is not only closely related to the choosing of the clearing agent type, but also related to the treatment time with the skin tissue. The clearing progress of different type optical clearing agent showed the order of 40% propylene glycol, 40% glucose and 40% glycerol.

[Gastric cancer detection using kubelka-Munk spectral function of DNA and protein absorption bands].

Differential diagnosis for epithelial tissues of normal human gastric, undifferentiation gastric adenocarcinoma, gastric squamous cell carcinomas, and poorly differentiated gastric adenocarcinoma were studied using the Kubelka-Munk spectral function of the DNA and protein absorption bands at 260 and 280 nm in vitro. Diffuse reflectance spectra of tissue were measured using a spectrophotometer with an integrating sphere attachment. The results of measurement showed that for the spectral range from 250 to 650 nm, pathological changes of gastric epithelial tissues induced that there were significant differences in the averaged value of the Kubelka-Munk function f(r infinity) and logarithmic Kubelka-Munk function log[f(r infinity)] of the DNA absorption bands at 260 nm between epithelial tissues of normal human stomach and human undifferentiation gastric cancer, between epithelial tissues of normal human stomach and human gastric squamous cell carcinomas, and between epithelial tissues of normal human stomach and human poorly differentiated cancer. Their differences were 68.5% (p < 0.05), 146.5% (p < 0.05), 282.4% (p < 0.05), 32.4% (p < 0.05), 56.00 (p < 0.05) and 83.0% (p < 0.05) respectively. And pathological changes of gastric epithelial tissues induced that there were significant differences in the averaged value of the Kubelka-Munk function f(r infinity) and logarithmic Kubelka-Munk function log[f(r infinity)] of the protein absorption bands at 280 nm between epithelial tissues of normal human stomach and human undifferentiation gastric cancer, between epithelial tissues of normal human stomach and human gastric squamous cell carcinomas, and between epithelial tissues of normal human stomach and human poorly differentiated cancer. Their differences were 86.8% (p < 0.05), 262.9% (p < 0.05), 660.1% (p < 0.05) and 34% (p < 0.05), 72. 2% (p < 0.05), 113.5% (p < 0.05) respectively. And pathological changes of gastric epithelial tissues induced that there were significant differences in the averaged value of the Kubelka-Munk function f(r infinity) and logarithmic Kubelka-Munk function log[f(r infinity)] of the carotene absorption bands at 480 nm between epithelial tissues of normal human stomach and human undifferentiation gastric cancer, between epithelial tissues of normal human stomach and human gastric squamous cell carcinomas, and between epithelial tissues of normal human stomach and human poorly differentiated cancer. Their differences were 59.5% (p < 0.05), 73% (p < 0.05), 258.9% (p < 0.05), 118.7% (p < 0.05), 139.2% (p < 0.05), and 324. 6% (p < 0.05) respectively. It is obvious that pathological changes of gastric epithelial tissues induced that there were significant changes in the contents of the DNA, protein and beta-carotene of gastric epithelial tissues. The conclusion can be applied to rapid, low-cost and noninvasive the optical biopsy for gastric cancer and provides a useful reference.

[Spectral characteristics of normal breast samples in the 350-850 nm wavelength range].

Spectral characteristics of normal female breast samples in the 350-850 nm wavelength range were measured using a UV/Vis/NIR spectrophotometer system with integrating sphere attachment for measuring the diffuse reflectance and transmittance. The optical properties of normal breast tissue in vitro were obtained by the inverse adding doubling method. And then the optical penetration depths in this spectral range were analyzed based on the principle of tissue optics. The results show that the reduced scattering coefficient of normal female breast tissue is significantly higher than the absorption coefficient in the 350-850 nm wavelength range. The reduced scattering coefficient decreases with the wavelength increment. It reaches maximum at shorter wavelengths with a decrease at longer wavelengths and ranges from 9.731 mm(-1) at 350 nm to 1.476 mm(-1) at 850 nm. The absorption coefficient of normal breast tissue is about from 0.798 mm(-1) at 350 nm to 0.102 mm(-1) at 850 nm. The maximal and minimal values are at 350 nm and 850 nm respectively. An absorption peak for the normal breast tissue is at 410 nm of wavelength with the value of 0.506 mm(-1), which belongs to hemoglobin. The absorption coefficient remains relatively constant when the wavelength is longer than 600 nm. The optical penetration depth increases with the wavelength increment and ranges about from 0.199 mm at 350 nm to 1.439 mm at 850 nm. Deep penetration depth noted in normal breast samples, especially at longer wavelengths, reflects the weak absorption and reduced scattering at these wavelengths. The calculated optical parameters of normal breast samples by the inverse adding doubling method agree well with the Monte Carlo simulations. This study may be useful for breast optical biopsy or the optical diagnosis of breast diseases.

[Colon adenoma detection using Kubelka-Munk spectral function of DNA and protein bands].

Differential diagnosis of human colon adenoma was studied using the Kubelka-Munk spectral function of the DNA and protein absorption bands at 260 and 280 nm in vitro. Diffuse reflectance spectra of tissue were measured using a spectrophotometer with an integrating sphere attachment. The results of measurement showed that for the spectral range from 590 to 1 064 nm pathological changes of colon epithelial tissues were induced so that there were significant differences in the averaged values of the Kubelka-Munk function f(r infinity) and logarithmic Kubelka-Munk function log [f(r infinity)] of the DNA absorption bands at 260 nm between normal and adenomatous colon epithelial tissues, and the differences were 218% (p < 0.05) and 68.5% (p < 0.05) respectively. Pathological changes of colon epithelial tissues were induced so that there were significant differences in the averaged values of the Kubelka-Munk function f(r infinity) and logarithmic Kubelka-Munk function log [f(r infinity)] of the protein absorption bands at 280 nm between normal and adenomatous colon epithelial tissues, and the differences were 208% (p < 0.05) and 59.0% (p < 0.05) respectively. Pathological changes of colon epithelial tissues were induced so that there were significant differences in the averaged values of the Kubelka-Munk function f(r infinity) and logarithmic Kubelka-Munk function log [f(r infinity)] of the beta-carotene absorption bands at 480 nm between normal and adenomatous colon epithelial tissues, and the differences were 41.7% (p < 0.05) and 32.9% (p < 0.05) respectively. Obviously, pathological changes of colon epithelial tissues were induced so that there were significant changes in the contents of the DNA, protein and beta-carotene of colon epithelial tissues. The conclusion can be applied to rapid, low-cost and noninvasive optical biopsy of colon adenoma, and provides a useful reference.

[Measurement of nasopharyngeal carcinoma tissue ex vivo by Raman spectroscopy].

Raman spectroscopy has shown its potential and advantages in detecting molecular changes associated with tissue pathology, which makes it possible to diagnose with optical methods non-invasively and real-time. A compact and rapid near-infrared (NIR)Raman system was developed using 785 nm diode laser, volume phase technology (VPT)holographic grating system and NIR intensified charge-coupled device (CCD)with a specially designed Raman fibre probe which can effectively reduce the interference of fluorescence and Rayleigh scattering, maximize the ability of Raman collection as well as correct the image aberration of a planar grating diffraction. Adopting this method, signal-to-noise ratio has been greatly improved and human tissue signals can be acquired in a short time. Raman signals from fat and musculature of fresh pork were measured and referenced for further optimization, then Raman spectra of nasopharyngeal carcinoma in vitro and the effect of storage time on them were measured in 1-5 s and discussed. The sensitivities and performance of the system will be further enhanced and more Raman data will be acquired and compared between normal and cancerous nasopharyngeal tissue, expecting to discover the statistical characteristics, which will benefit the diagnosis and treatment of early nasopharyngeal carcinoma or other tumors.

[Reflectance spectroscopy study of low-frequency ultrasound and glycerol on skin optical clearing].

In order to find a non-invasive way to improve the efficacy of skin optical clearing with topically applied optical clearing agents, the authors researched the changes of reflectance spectroscopy of skin tissues before and after being dealt by low-frequency ultrasound and osmotic active chemical agents within the wavelength range of 400-860 nm, and the degree of changes in reflectance spectroscopy of each group skin during 0-15 min and 15-30 min at 580 nm. The measurements were performed using a AvaSpec-2048 optical fiber spectrometer with integrating-sphere setup. The results of measurements showed that there were a few changes of the reflectance spectroscopy of skin tissues in the control group (Group 1) (The skin tissue was dealt with nothing. ) during the whole observation; But in the Group 2 (The skin tissue was dealt with only low-frequency ultrasound), it was found that the reflectance of the skin tissue showed a significant increase comparing 15 min with 0 min, but the changes in reflectance of the tissues slowly restored the original form following the longer time since the ultrasound stopping; There was also a very fast changes in reflectance of the skins in the Group 3 (the skin were dealt with only 80% glycerol) compared with that in the Group 1. The authors also found that there was a very distinct decrease in the reflectance of skin tissues dealt with both low-frequency ultrasound and 80% glycerol group (Group 4), especially during the 0-15 min, and its speed was 4.0 times that of the Group 1 and 2. 3 times that of Group 3 (During 0-15 min, the reflectance of skin tissues in the Group 1 decreased 1.896%; the reflectance of skin tissue in the Group 3 decreased 3.316%; the reflectance of skin tissues in the Group 4 decreased 7.551%). From the above results, it can be clearly seen that the low-frequency ultrasound and 80% glycerol not only have synergistic effect on optical clearing of skin tissue in vitro, but can change the optical clearing of the skin tissue in a short time.

[Comparative study of reflectance spectroscopy of human laogong acupoint and non-acupoint tissues irradiated by near-infrared laser].

Characteristics and differences of reflectance spectroscopy of human Laogong acupoint and non-acupoint tissues before and after irradiation by different power of laser were studied in the spectral range from 400 to 1 000 nm. A wavelength 808 nm semiconductor laser was used for irradiation at the power of 20, 50 and 100 mW for ten minutes. Reflectance spectra of human Laogong acupoint and non-acupoint tissues were measured by using an AvaSpec-2048 optical fiber spectroscopy with an integrating sphere attachment. The result shows that before irradiation the shape of the reflectance spectra of Laogong acupoint and non-acupoint is similar, they have the same troughs at 423, 544, 577 and 980 nm, and the reflectance for Laogong acupoint and non-acupoint at these wavelengths is 17.1%, 26.1%, 25.9% and 35.0%, and 17.1%, 27.6%, 28.1% and 36.5% respectively. But from 475 to 1 000 nm, the reflectance of Laogong acupoint is smaller than that of non-acupoint. After being irradiated by semiconductor laser at the power of 20, 50 and 100 mW, there is a very significant decrease in the reflectance of Laogong acupoint compared to that before irradiation, and the higher the power, the lower the reflectance. But there is just a small decrease in the reflectance for non-acupoint compared to that before irradiation. From the above results, it is clearly seen that Laogong acupoint is different from non-acupoint on reflectance spectroscopy, and Laogong acupoint is more sensitive to laser irradiation than non-acupoint tissue.

Differences in optical transport properties between human meridian and non-meridian.

This study is to present a new scheme for the detection of human meridian system non-invasively. The optical transport properties along the pericardium meridian and a non-meridian path about 1 cm away from the meridian were measured non- invasively on 20 healthy people in vivo. 633 nm, 658 nm and 785 nm red lasers were used for irradiation, and the diffuse light emittances at different points on meridian and non-meridian directions were collected respectively and compared. Our study suggested that the light propagation characteristics along both the meridian and non-meridian directions conformed to the Beer's exponential attenuation law. Statistical analysis of the results suggested that the optical properties of human meridian differ from those of the surrounding tissue (p < 0.05), and the light attenuation is less when propagating along the pericardium meridian than along the non-meridian direction. These findings not only confirmed the objective existence of acupuncture meridians, but also shed new light on the understanding of meridians.

Appearance of human meridian-like structure and acupoints and its time correlation by infrared thermal imaging.

The meridians and acupoints of human bodies at natural condition are investigated among 30 healthy volunteers by infrared thermal imaging technique. The results give clear evidence of the existence of infrared radiant tracks along human meridian courses. The time dependent evolution of the infrared radiant track is observed for the first time. The time rhythm of acupoints is also studied. Our findings not only support the view that infrared radiant tracks along human meridian courses is a normal vital and physiological phenomenon appearing in human beings, but also offer a potential method for noninvasive diagnostic by studying the physiological function and pathological change of meridians or acupoints by means of thermography.

[The impact of blood content in skin tissue on skin spectra].

Based on the analysis of skin structure, and the production mechanism of fluorescence and reflectance spectra, six-layer optical models for skin of different blood content in both upper blood plexus and deep blood plexus were developed, and Monte Carlo simulation was made. The result shows that (1) Both fluorescence and reflectance spectra could reflect the change of blood content in skin tissue; (2) The impact of blood content in upper blood plexus on skin spectra intensity is large, while the impact of blood content in deep blood plexus on skin spectra intensity is small; (3) Fluorescence and reflectance spectra could be used to detect or analyze change of blood content in skin tissue, especially to test the treatment and tune of dermatosis with plexus or blood pathological changes in upper dermis.

[Comparison of light attenuation characteristics and optical penetration depths between native and coagulated human liver tissues].

A double-integrating-spheres and IAD method were used to study the differences in the optical penetration depths (OPDs) and light attenuation (LA) native and coagulated human liver tumors and liver tissues at the wavelengths of 680, 720, 780, 810, 850 and 890 nm of Ti: Sapphire laser. The results of measurement showed that the OPDs for native and coagulated human liver tumors and liver tissues at six different wavelengths obviously increase with increasing laser wavelength, the OPDs of coagulated human liver tumors and liver tissues at six different wavelengths were significantly smaller than that of native human liver tumors and liver tissues at the same wavelength respectively (P<0.05), and the OPDs of native and coagulated human liver tumors at six different wavelengths were significantly bigger than that of native and coagulated human liver tissues at the same wavelength respectively (P<0.05). The LA for native and coagulated human liver tumors and liver tissues at six different wavelengths obviously decreases with increasing laser wavelength, and the LA for coagulated human liver tumors and liver tissues at six different wavelengths is significantly bigger than that for native human liver tumors and liver tissues at the same wavelength respectively (P<0.05). The LA for native and coagulated human liver tumors at six different wavelengths is significantly bigger than that for native and coagulated human liver tissue at the same wavelength respectively (P<0.05).

[Fluorescence spectral characteristics of human blood and its endogenous fluorophores].

The three-dimensional fluorescence spectra and excitation-emission matrix of human blood were measured, and an attempt was made to exploit the endogenous fluorophores of major peaks in the UV and visible. The result indicates that the absorption peaks of human blood appear at 274, 345, 415, 541 and 576 nm. Based on the analysis of fluorescence excitation-emission matrix, the major emission peaks of human blood occur at excitation-emission wavelength pairs of 260-630, 280-340, 340-460 and 450-520 nm, which are attributed to endogenous porphyrins, tryptophan, reduced nicotinamide adenine dinucleotide (NADH) or reduced nicotinamide adenine dinucleotide phosphate (NADPH), and flavin adenine dinucleotide (FAD), respectively. These results can be used to analyze and explain the effect of blood on the distortion of fluorescence signal of human tissues for optical diagnosis.

[Fourier transform infrared and near-infrared Raman spectra of human red blood cell].

The human red blood cell was studied by Fourier transform infrared and near-infrared Raman spectroscopy.The assignment of the characteristic groups of human red blood cell structure was basically confirmed. At the same time, the authors observed that the intensity of different Raman shift signal has different varying law when the power of laser is changing. Near-infrared laser Raman spectroscopy combined with infrared spectroscopy is an effective method to study the structure of human red blood cell.

Autofluorescence excitation-emission matrices for diagnosis of colonic cancer.

AIM: To investigate the autofluorescence spectroscopic differences in normal and adenomatous colonic tissues and to determine the optimal excitation wavelengths for subsequent study and clinical application. METHODS: Normal and adenomatous colonic tissues were obtained from patients during surgery. A FL/FS920 combined TCSPC spectrofluorimeter and a lifetime spectrometer system were used for fluorescence measurement. Fluorescence excitation wavelengths varying from 260 to 540 nm were used to induce the autofluorescence spectra, and the corresponding emission spectra were recorded from a range starting 20 nm above the excitation wavelength and extending to 800 nm. Emission spectra were assembled into a three-dimensional fluorescence spectroscopy and an excitation-emission matrix (EEM) to exploit endogenous fluorophores and diagnostic information. Then emission spectra of normal and adenomatous colonic tissues at certain excitation wavelengths were compared to determine the optimal excitation wavelengths for diagnosis of colonic cancer. RESULTS: When compared to normal tissues, low NAD(P)H and FAD, but high amino acids and endogenous phorphyrins of protoporphyrin IX characterized the high-grade malignant colonic tissues. The optimal excitation wavelengths for diagnosis of colonic cancer were about 340, 380, 460, and 540 nm. CONCLUSION: Significant differences in autofluorescence peaks and its intensities can be observed in normal and adenomatous colonic tissues. Autofluorescence EEMs are able to identify colonic tissues.