It has been reported that low-power laser irradiation (LLI) can modulate various biological processes including cell proliferation. We have demonstrated that 808 nm LLI has a potential of suppressive effect on the cell proliferation of human-derived glioblastoma A-172. To reveal whether such an effect has a wavelength-dependency, the present study was designed to examine effects of 405 nm LLI (27 mW) on the A-172 cell proliferation using the same experimental procedures as well as methods. The A-172 cells were cultivated in culture dishes or a 96-well plate. No irradiation was applied in control-group, whereas in experimental group, the center of dish or the selected well was irradiated for 20, 40 and 60 min, respectively. Cells were cultivated in CO₂ incubator for 2 days. The dishes or wells were photographed at pre-, just post-irradiation, 24 and 48 hrs after irradiation with a digital camera. Cell counting was performed on the PC monitor and the ratio of cell proliferation was measured. MTT assay was also applied at 48 hrs after irradiation and viable cells were estimated by means of colorimeter. Both analyses showed that 405 nm LLI provided a significant suppressive effect on the proliferation of A-172 cells (p<0.05 or p<0.01), and that the effect of LLI showed a tendency of dose-dependency. In addition, 405 nm LLI induced a morphological change of A-172 as well as cell death more clearly than those induced by 808 nm LLI application. It is concluded that 808 nm and 405 nm LLIs have a potential of suppressive effect on the cell proliferation of human-derived glioblastoma A-172, but the latter is more effective than the former application. Since 808 nm LLI did not induce a morphological change or cell death but 405 nm LLI did, it is suggested that the effect of 808 nm LLI is based on a retardation of cell cycle whereas that of 405 nm LLI is based on a facilitation of cell death.

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The medical application of femtosecond lasers has certain disadvantage such as a photochemical damage to living tissue caused by multiphoton absorption, which should be addressed. In this study, changes in the UV absorbance of amino acid by femtosecond laser irradiation are investigated. Histidine, which is an essential amino acid, is selected as the sample. The results indicate that a change in UV absorption is observed around 270 nm. The amount of change depends on the peak intensity of the laser, suggesting that the structure of histidine is influenced by multiphoton absorption during the femtosecond laser irradiation.

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It is well-known that majority of the histological type of cervical cancer is squamous cell carcinoma (SCC). Recently, the proportion of adenocarcinoma (AC) cases is increasing in Japan. Concerning the squamous intraepithelial lesion of the cervix, consensus of the treatment was already estallished; namely, both LASER vaporization for dysplastic lesion and cervical conization for CIN3 and FIGO stage Ia1 of SCC are acceptable in order to preserve the patients' fertility. The methods of the cervical conization vary; cold knife, LASER, high-frequency electrical scalpel, ultrasonic scalpel, and loop electrosurgical excision procedure (LEEP). Among these, cervical conization by LASER has a cure rate of almost 100% for CIN3. Besides, conization for stage Ia1 of SCC can avoid hysterectomy if both surgical margin and lymph-vascular space invasion are negative.
However, concerning AC, management of treatment needs extra precaution even though these are at early stages, i.e., adenocarcinoma in situ (AIS) or FIGO stage Ia1. First, early stage of AC is difficult to diagnose under colposcopy compared with squamous lesion. For this reason, correct pathological evaluation like the stromal invasion of cancer tissue is sometimes missing. Diagnosis of microinvasive adenocarcinoma is frequently made in the conization specimen. In “Guidelines for the treatment of cervical cancer (Version year 2007)” by Japan Society of Gynecologic Oncology, hysterectomy is recommended for the treatment of AIS (stage 0) even though surgical margin is negative in conization specimen. The rationale for this recommendation is that glandular epithelial lesion has skip lesion in distant spaces and around 20% of cases have possible remnant lesion in the residual uterus even though surgical margin is negative in conization specimen. Secondly, concerning the microinvasive adenocarcinoma (stage Ia), individualizations of the treatment should be considered by the depth of stromal invasion. Modified radical hysterectomy or radical hysterectomy including pelvic lymphadenectomy is chosen in patients having deep stromal invasion. Total hysterectomy without lymphadenectomy is chosen if the invasion is shallow. Cervical conization is considered if the patient strongly hopes to preserve her fertility.

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Photodynamic diagnosis (PDD) has been applied for the detection of flat lesion of bladder cancer, in particular carcinoma in situ. Recent meta-analysis has revealed PDD has an evidence of improving patient outcome in terms of tumor recurrence as well as finding optically non-visible tumor lesions. This effect may contribute to standardization of the TURBT treatment among institutions. Oral administration of 5-ALA may confer the PDD on the new detection method for other urological malignancies, such as the detection of surgical margin during partial nephrectomy, or radical prostatectomy. Herein, upfront publications concerning PDD on urological malignancies are reviewed in this article.

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Overview of transmission mechanisms, materials, and structures of various optical fibers for medical applications such as laser surgery, optical biopsy, and optical imaging is described. The paper gives explanations about common silica-glass optical fiber and infrared fiberoptics composed of specialty materials. Various properties of hollow optical fibers based on transmission mechanism that is totally different from glass optical fibers are also explained.

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Endoscopic optical coherence tomography (E-OCT) has been improved to measure three-dimensional (3D) sectional imaging advancing performances such as speeds and sensitivities in optical probes and OCT. The low-voltage driven MEMS optical probe with diameter 2.8 mm and length 12 mm was developed with a polarization sensitive OCT to achieve the spatial resolution of 25 μm. 3D sectional images (1.2 × 10 × Depth 1.4 mm) of in vivo human vocal folds have been measured with 15-20s. The carcinomas were distinguished from normal tissues.

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An optical biopsy technique based on optical spectroscopy attracts keen interest of clinicians. The instrument for the optical biopsy needs to have optical fiber probes for in situ measurement in the body. Raman spectroscopy which is suitable for fiber optic applications has high potential in analysis of biological materials. On the other hand, it is difficult to extend Raman spectroscopy into image application. It needs supporting new techniques such as autofluorescence hyper-spectral image to process the Raman data more familiar and useful for the clinicians. The present manuscript discusses prospect and potential of Raman spectroscopy in the practical clinical use.

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Development of minimally invasive medical devices using microfabrication techniques and optical fiber technology have been described. Microfabricaion, polymer coating and mounting micro mechanical structures at the optical fiber end have been performed and mentioned. Development of laser therapeutic tool with movable mirror and thin endoscope with electromagnetic solenoid coil using microfabrication technique and equipment have been mentioned. It is expected that these fabrication techniques and microdevices can enlarge possibility of optical fiber application for minimally invasive medicine.

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In order to understand the physiological function and pathological reactions of cells, microscopic observations of cellular activities at their molecular level deep inside the tissue in the living animal are necessary. To this end, we developed a fiber-coupled confocal microscope which sends a fine imaging bundle to the deep part of the tissue by a penetrating action just like that of an injection needle. Microscopic view can be obtained by the fiber system from the field of 500 μm in width, and 10 cm or more in depth. There are still many problems remaining unsolved. However, none of the problems face the physical limit, and thus are improving rapidly. Several problems associated with temporal and spatial resolutions, and optical sectioning capability were explained, and discussed toward further advancements of the method.

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