Detection of ER stress in vivo by Raman spectroscopy.

The endoplasmic reticulum (ER) is an organelle in which most membrane and secretory proteins are synthesized. If these proteins are not folded correctly, unfolded proteins accumulate in the ER lumen, causing a cellular situation known as ER stress. Recently, many studies on the relationship between ER stress and diseases have been reported.

Endoscopic observation of N-methyl-N'-nitro-N-nitrosoguanidine-induced gastric carcinogenesis in rat using a newly-developed flexible endoscope.

Endoscopy can be used for sequential observation of gastric carcinogenesis in animal models. In the present study, we applied endoscopic examination and biopsy technique on N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced stomach cancer in rats using a newly-developed flexible 2.5 mm endoscope.

Improvement and analysis of a micro Raman probe.

A micro Raman probe (MRP) with a 600 microm diameter, which we previously reported as the narrowest achieved to date, was further improved by introducing high-quality optical filters and a collecting lens at the tip. We fabricated the MRP with a high collection efficiency, a wider collection wavelength, and a high signal-to-noise ratio. We compared two types of probes: one with a lens-tipped end and one with a flat tip.

In vivo Raman study of the living rat esophagus and stomach using a micro-Raman probe under an endoscope.

A small endoscope system equipped with a micro Raman probe is developed for in vivo Raman measurements in living rats. The measurements are done under anesthesia and artificial respiration to minimize the impact on the rats. Raman spectra of living rat esophagus and stomach are successfully measured.

Intravascular Raman spectroscopic catheter for molecular diagnosis of atherosclerotic coronary disease.

An intravascular catheter for Raman spectroscopic detection and analysis of coronary atherosclerotic disease has been developed. The catheter, having an outer diameter of 2 mm, consisted of a side-view-type micro-Raman probe, an imaging fiber bundle, a working channel (injection drain), and a balloon. By inflating the balloon, the probe was brought close to the inner wall of a modeled blood flow system and detected a phantom target buried in the wall.

Fluorescence-suppressed Raman technique for quantitative analysis of protein solution using a micro-Raman probe, the shifted excitation method, and partial least squares regression analysis.

A practical Raman analyzing technique with suppression of the strong fluorescent background in order to obtain quantitative information is proposed in the present study. The technique is based on the shifted excitation method and partial least squares regression (PLSR) analysis. The Raman system consists of a single Raman spectrometer, a background-free electrically tunable Ti:Sapphire laser (BF-ETL), and a micro-Raman probe (MRP).

Raman probe using a single hollow waveguide.

A simple Raman probe was realized using a single flexible hollow waveguide (HW). A HW coated with a silver film, which had reasonable transmission and little optical background noise, was used as a bidirectional transmission fiber for both the excitation and collection of Raman scattered light. The HW itself generated no Raman scattering or fluorescence noise during transmission.

Micro-optical fiber probe for use in an intravascular Raman endoscope.

We believe that we have developed the narrowest optical-fiber Raman probe ever reported, 600 microm in total diameter, that can be inserted into coronary arteries. The selection of suitable optical fibers, filters, and a processing method is discussed. Custom-made filters attached to the front end of a probe eliminate the background Raman signals of the optical fiber itself.