Kazufumi Nakamura

Optical frequency domain ranging by a frequency-shifted feedback laser

This paper describes the theoretical and experimental study of a new technique for optical frequency domain ranging (OFDR) by a frequency-shifted feedback (FSF) laser. In conventional OFDR, a frequency chirped single-mode laser is used as a light source to convert a distance into a beat frequency, and a tradeoff exists between measurement range and resolution. The FSF laser output consists of periodically generated chirped frequency components whose chirp rate is faster than 100 PHz/s (P=10/sup 15/), By use of the FSF laser, the tradeoff is removed and long-distance high-resolution OFDR is realized In the experiment, a distance of 18.5 km was measured with a resolution of 20 mm.

Basigin Mediates Pulmonary Hypertension by Promoting Inflammation and Vascular Smooth Muscle Cell Proliferation

Rationale: Cyclophilin A (CyPA) is secreted from vascular smooth muscle cells (VSMCs) by oxidative stress and promotes VSMC proliferation. However, the role of extracellular CyPA and its receptor Basigin (Bsg, encoded by Bsg) in the pathogenesis of pulmonary hypertension (PH) remains to be elucidated. Objective: To determine the role of CyPA/Bsg signaling in the development of PH. Methods and Results: In the pulmonary arteries of patients with PH, immunostaining revealed strong expression of CyPA and Bsg. The pulmonary arteries of CyPA+/– and Bsg+/– mice exposed to normoxia did not differ in morphology compared with their littermate controls. In contrast, CyPA+/– and Bsg+/– mice exposed to hypoxia for 4 weeks revealed significantly reduced right ventricular systolic pressure, pulmonary artery remodeling, and right ventricular hypertrophy compared with their littermate controls. These features were unaltered by bone marrow reconstitution. To further evaluate the role of vascular Bsg, we harvested pulmonary VSMCs from Bsg+/+ and Bsg+/– mice. Proliferation was significantly reduced in Bsg+/– compared with Bsg+/+ VSMCs. Mechanistic studies demonstrated that Bsg+/– VSMCs revealed reduced extracellular signal–regulated kinase 1/2 activation and less secretion of cytokines/chemokines and growth factors (eg, platelet-derived growth factor-BB). Finally, in the clinical study, plasma CyPA levels in patients with PH were increased in accordance with the severity of pulmonary vascular resistance. Furthermore, event-free curve revealed that high plasma CyPA levels predicted poor outcome in patients with PH. Conclusions: These results indicate the crucial role of extracellular CyPA and vascular Bsg in the pathogenesis of PH.

Novel PMD measurement method based on OFDR using a frequency-shifted feedback fiber laser

We propose a new method to measure polarization mode dispersion (PMD) in optical fibers based on optical frequency domain reflectometry technique. In this method the PMD is directly determined from the beat frequency generated by interference between lights from the Fresnel reflection at the end of the device under test, which makes the measurement at single end of the device possible. An automated PMD measurement system is demonstrated on polarization maintaining fibers with a frequency-shifted feedback fiber laser as a light source.

TRPM4 Mutation in Patients With Ventricular Noncompaction and Cardiac Conduction Disease

Left ventricular noncompaction (LVNC) is characterized by abnormally prominent trabeculations and deep intertrabecular recesses in the left ventricle.1 LVNC can range from asymptomatic to end-stage heart failure and lethal arrhythmias, which lead to sudden cardiac death. Mutations associated with sarcomere proteins, ion channels, and developmental transcription factors have been identified in patients with LVNC.1nnThe proband was diagnosed with incomplete right bundle branch block at 5 years old. At 16 years old, he was diagnosed with complete right bundle branch block and frequent premature ventricular contraction. At 25 years old, he was diagnosed with complete atrioventricular block and left ventricular dysfunction, and a permanent pacemaker was implanted. His echocardiogram exhibited prominent trabeculations and deep intertrabecular recesses in the apical to midventricular lateral wall. The noncompacted zone/compacted zone ratio was 2.3 (Figure A). Subsequently, symptoms of left ventricular dysfunction became progressively more severe despite medication and cardiac resynchronization therapy, and he eventually died of heart failure. The autopsy findings showed dilated ventricular lumen, whitish and filamentous prominent trabeculations in the ventricle, and thin compacted myocardium (Figure B). Microscopic findings showed displacement of the atrioventricular node by a fatty tissue (Figure C) and loss of the Purkinje fibers. Thickened endocardium and subendocardial fibrosis were seen, and fibrosis of trabeculae and interventricular septum were more prominent than previously reported cases.2 Mild anastomosing broad trabeculae and staghorn-like endocardial lined spaces were seen (Figure D). A fibrous band was not apparent. These findings were consistent with LVNC …

Improvement of a measurement range of optical frequency domain reflectometry by a frequency-shifted feedback laser

Summary form only given. Optical reflectometry is of importance in various fields such as diagnostics of optical communication network, fiber optic sensors and so on. To implement these applications, it is favorable to achieve a better spatial resolution than 1 cm over an operating range of tens of kilometers. Such performance, however, has not yet been reported as far as we know. Recently we demonstrated an optical frequency domain reflectometry (OFDR) using a frequency-shifted feedback (FSF) laser, and a distance of 3.7 km was measured with a spatial resolution of 9.4 mm. In the paper we demonstrate a long distance (>10 km), high resolution (/spl sim/1 cm) OFDR by the FSF laser.