Cell membranes in tissue can be permeabilized by applying photomechanical waves (PMWs) that are generated by irradiating a laser-absorbing material with an intense pulsed laser. In the present work, we attempted to deliver small interfering RNAs (siRNAs) for silencing the expression of intermediate filament proteins, which suppress axonal regeneration, into the injured spinal tissues of rats by applying PMWs. Functional recovery was assessed daily by an open-field test. The treatment led to significant improvement of locomotive function from five days post-injury for the rats with PMW-mediated siRNAs delivery, when compared with those with spinal cord injury (SCI) alone and those with siRNA injection after SCI. This would be due to the delivery of siRNAs into the deeper spinal tissue by the effect of PMWs. This was well revealed by the separate experiment using fluorescent probe-labeled siRNA.

View full abstract

Photodynamic therapy (PDT) and photodynamic diagnosis (PDD) have attracted much attention as relatively noninvasive methods for cancer treatment and diagnosis, and new photosensitizers with a property of high accumulation in tumors have been extensively investigated. The use of a drug-delivery system (DDS) for the delivery of photosensitizers is a promising approach for improved safety and enhanced efficacy of PDT and PDD. We established a novel DDS-type photosensitizer, a dendrimer photosensitizer-encapsulated polymeric micelle. In this review, the design of the agent and its usefulness in PDT and PDT are shown.

View full abstract

[in Japanese]

View full abstract

In recent year, cervical cancer has been increased in young women, so fecundity-conserving therapy, such as cervical conization and radical trachelectomy, is important. Various kinds of cervical conization procedures are available; LASER, cold knife, loop electrosurgical excision procedure (LEEP), ultrasonic scalpel. LASER vaporization is an advantage for hemostasis. Conization for carcinoma in situ and microinvasive squamous carcinoma, stage ⅠA1 could be final treatment without hysterectomy. However, with regard to microinvasive adenocarcinoma, management of treatment needs extra precaution.

View full abstract

Photodynamic therapy (PDT) is a conservative treatment modality using the combination of a photosensitizer possessing high tumor affinity and irradiation with laser at a low intensity low level laser emission and which enables selective destruction of cancerous or dysplastic cells while preserving the uterus. The indications for PDT in Japan are early stage lung cancer (including a part of advanced or recurrent lung cancer), early stage superficial esophageal cancer, early stage superficial gastric cancer, and dysplasia and early stage cervical cancer of the uterine cervix. Porfimer sodium (Photofrin) is approved in Japan as the photosensitizer for the gynecologic cancer. Excimer Dye Laser and YAG-OPO laser are approved in Japan as the laser apparatus for PDT. In this paper, I will describe current status and future perspectives of the PDT for early stage cancer and dysplasia of the uterine cervix, PDT in the foreign countries, and R&D status of the second generation of PDT for the uterine cervical cancer in Japan.

View full abstract

We have developed endoscopic laser irradiation devices for minimal invasive laser therapy of twin-to-twin transfusion syndrome, which is circulatory derangement between twin fetuses. In this paper we propose three devices, 1) a miniature bending laser manipulator, 2) a composite-type optical fiberscope to irradiate center point of the fiberscopic image, 3) a laser steering endoscope to locate ablation point in the endoscopic image. These technologies are not only applicable to near-future fetal surgery but also to general surgery.

View full abstract

While conventional ultrasonic testing and cytodiagnosis have not been shown to be sufficiently valid for early diagnosis and treatment essential to improve endometrial cancer treatment, laser therapy facilitates observation and treatment of the narrow part of the uterine body, which is difficult to approach. The quality of images produced by a minimally invasive laser therapy system developed by the Japan Atomic Energy Agency is similar to that obtained with existing hysteroscopes. Further, it is easier to irradiate a laser beam onto target tissues. This technology may provide a new therapeutic strategy for endometrial cancer.

View full abstract

Photodynamic therapy (PDT) has been established as a useful treatment for early stage cancer and dysplasia of uterine cervix. Multidisciplinary therapy is necessary for recurrent lesion of cervical cancer after hysterectomy. However, many cases are repeat recurrence, and it is difficult to complete treatment after radiation therapy. Occasionally surgical treatment such as total pelvic exenteration makes patient’s condition worse in terms of quality of life. PDT can be performed without systemic side effect, and it was suggested that PDT would become one of the effective treatment modalities for recurrent cervical cancer. We expect PDT could yield excellent result in recurrent cervical cancer as part of our new therapeutic strategy.

View full abstract

[in Japanese]

View full abstract

Many kinds of lasers have been used in medical applications, and new laser technologies will also adopted for photo-diagnostics and photo-therapy. In these special review articles, we tried to introduce the new laser technologies. As an introductory review, traditional and standard line-up of medical lasers is reviewed from a point of users’ view.

View full abstract

The progress of micro solid-state photonics has been offered the tremendous advantages in the microchip laser as a high brightness giant pulse laser. Successfully developed mega watt sub-ns pulse microchip lasers are opening new fields in the pulse gaped sub-ns region. In this paper, we’d like to review our giant-pule microchip laser and its nonlinear wavelength conversion properties.

View full abstract

Er-doped fluoride grass fiber lasers are expected to be put into practical use as a high-power laser source in the 2.7-μm band. This article provides a technical overview of the mid-infrared Er fiber lasers, and reviews several state-of-the-art fiber lasers.

View full abstract

Selective laser melting (SLM) is a rapid prototyping (RP) technique that allows producing complex three-dimensional parts rapidly from CAD (computer aided design) models by sintering successive thin layers of powder with a laser beam. In the industrial world, especially, SLM with a metallic powder is a practical method for trial manufacturing and development of molding dies and mechanical parts and for quick manufacture of limited runs of end products. In the medical world, SLM is also an attractive option for manufacturing various custom-made implants. In this review article, we introduce the principles, characteristics and technical trends of the SLM process using biomaterials. We also partially introduce the results of our research into the SLM process using pure titanium, a metallic biomaterial.

View full abstract

Since 2004, fractional laser devices have been developed and these have been applied to skin rejuvenation, wrinkle treatment, scar treatment and so on. Now there are various types of fractional laser devices (1440 nm, 1540 nm, 1550nm, 1927 nm, 2790 nm and 10600 nm) developed by manufacturer of lasers. Each fractional laser system has the high optical technologies and it is necessary for users to understand the optical characteristics of system for better clinical results.

View full abstract