Kanji Nakai

Inhibition of experimental vasospasm by pretreatment with ultraviolet light irradiation in a rat femoral artery model.

OBJECTIVEChronic cerebral vasospasm is resistant to conventional treatments despite recent advances in treatment modalities. We studied the preventive effect of ultraviolet (UV) irradiation on development of vasospasm and its mechanism in a rat femoral artery model. METHODSThe rat femoral artery model for vasospasm was used in this investigation (n = 108). The femoral arteries were divided into four groups: empty and no irradiation (control), UV irradiation (UV group), blood placement (VS group), and blood placement after UV irradiation (VS + UV group). Luminal area was measured, and smooth muscle cell counts in the medial layer of the vessel wall were obtained. An immunohistochemical study was performed with cross sections of fixed femoral arteries at 12 hours and 1, 3, 5, 7, and 49 days after blood placement. The rings of femoral arteries on Day 7 were subjected to pharmacological study. RESULTSPretreatment with UV irradiation (VS + UV group) resulted not only in significant inhibition of chronic vasospasm but also in a significant decrease in smooth muscle cells compared with the VS group on Days 5 and 7. The UV-treated arteries (UV and VS + UV groups) exhibited a significant number of Bax- and Bcl-2-positive cells on Days 5 and 7, but few CPP-32 positive cells were observed at the same time points. In the pharmacological study, contractile response to KCl or phenylephrine was reduced significantly in the UV-treated arteries. CONCLUSIONThese results imply that UV irradiation prevents chronic vasospasm and suggest that UV-induced cell death plays an important role in the preventive effect without causing complications during the chronic period.

Heat and Photolytic Nitric Oxide are Essential Factors for Light-induced Vascular Tension Changes

Abstract.Light induces various vascular tension changes, but these phenomena and their mechanisms remain controversial. We hypothesise that photocontraction results from the thermal effect, and that photorelaxation results from the non-thermal effect of photochemical nitric oxide generation. The isometric tension of a rat aortic ring was measured during laser light irradiation at various wavelengths with constant heat generation. Visible irradiation (458 nm, 514.5 nm) induced either photorelaxation (the tension increment was −20% of the contracted state induced by noradrenaline) or photocontraction (+7.8%); UV irradiation (351 nm) induced only photorelaxation (−41%), and near-IR irradiation (800 nm) produced only photocontraction (+11%). In the vascular tissue, photocontraction increased with deposited light energy, which was proportional to the temperature elevation. Simply heating the vascular tissue also resulted in vasocontraction. Photorelaxation by UV occurred even in the absence of endothelium, and was significantly reduced to 49% of control levels of photorelaxation by the guanylate cyclase inhibitor, methylene blue. Photorelaxation was not reduced by the nitric oxide synthetase inhibitors, Nω-monomethyl-l-arginine (l-NMMA) and Nω-nitro-l-arginine methyl ester (l-NAME). We conclude that photocontraction is produced by the thermal effect resulting from deposited light energy. Photorelaxation might be induced by endothelium-independent nitric oxide generation, which seems to result from the photochemical effect due to photon energy.

Successful treatment of a thrombosed posterior cerebral artery aneurysm causing obstructive hydrocephalus

The authors report a 49-year-old man who presented with obstructive hydrocephalus caused by a thrombosed posterior cerebral artery aneurysm. He underwent an endoscopic third ventriculostomy for the obstructive hydrocephalus followed by endovascular occlusion for the aneurysm. To our knowledge, this is the first report of a thrombosed posterior cerebral artery aneurysm presenting with obstructive hydrocephalus treated by the combination of endoscopic and endovascular techniques.

Long-term Effects of UV Light on Contractility of Rat Arteries In Vivo¶

Several studies have shown that UV irradiation may be effective for preventing vascular restenosis or vasospasm. However, the long‐term effects of UV light on the physiological properties of vessels such as arterial tension have not been elucidated. We therefore studied the long‐term effects of UV using rat carotid arteries treated with UV‐B light (wavelength = 313 nm, total energy = 14 mJ/mm2). The animals were sacrificed at 1, 7 and 14 days after UV light exposure, and the carotid arteries were studied by light microscopy and the contractile responses of isolated arterial rings were recorded under isometric tension. UV treatment had induced a substantial loss of smooth muscle cells (SMC) along the entire circumference of the media on days 7 and 14, whereas loss of SMC on day 1 was negligible. Contractile responses of arteries that had been exposed to UV light were significantly reduced on days 1, 7 and 14. The susceptibility of UV‐treated arteries to phenylephrine and prostaglandin F2α was significantly decreased on days 1 and 7, but decreased susceptibility was not seen on day 14. Acetylcholine‐induced relaxations were not altered by UV treatment. These results suggest that the long‐term effect of UV light is an attenuation of smooth muscle contractility without impairment of endothelial function.

Uncooled infrared camera for the noninvasive visualization of the vascular flow in an anastomotic vessel during neurological surgery: technical note.

We herein present our experience to assess intraoperative confirmation of vascular patency with an uncooled infrared camera in extracranial–intracranial (EC-IC) bypass surgery. This camera had distinguishing characteristics, including its small size, light weight, and adequate temperature resolution (< 0.022 degrees). We used a simplified zoom germanium lens as a preliminary study to verify the potential of using this camera to assess the vascular flow of the end-to-side anastomosis model in rats. In addition, we evaluated the vascular flow in continuous clinical series using this infrared camera during EC-IC bypass in 14 patients (17 sides). This infrared camera offers real-time information on the vascular patency of end-to-side anastomosis vessels of all relevant diameters. The spatial resolution and image quality are satisfactory, and the procedure can be safely repeatable. We have shown that the infrared camera could be a new and feasible technology for intraoperative imaging of the vascular flow and is considered to be clinically useful during cerebrovascular surgery.

Ultraviolet light attenuates vasospasm development: Low intensity 325 nm illumination in animal model

We studied whether prophylactic low-intensity ultraviolet light (UV) irradiation reduces development of delayed cerebral vasospasm in rabbit model. Eleven rabbits had carotid angiography and placement of silicon sheaths around the right common carotid artery (CCA). Just before the placement, CCAs of 6 in the 11 animals were adventitiously exposed to UV (10 mJ/mm2) emitted from a helium-cadmium laser (wavelength equals 325 nm). Sheaths were filled with autologous blood in all of 11 animals. Vasospasm developed 24 to 48 hours (Day 2) later. The CCA luminal diameter without UV irradiation was 77% of the Day 0 state. The prophylactic laser treatment reduced the development of vasospasm, 90% of the Day 0 state. Histological examination of the treated CCA revealed extended smooth muscle cells. There was no endothelial damage. These results suggest that UV is effective for prophylaxis of cerebral vasospasm.

Relief of vasospasm by intravascular ultraviolet irradiation

We investigated the photovasorelaxation with intravascular transluminal irradiation using in vivo model. A 2.5 Fr. catheter was inserted in the femoral artery of a rabbit under anesthesia. A 400 micrometers diameter quartz fiber was inserted through the catheter. The catheter was withdrawn from the distal end to the proximal end of the exposed femoral artery without laser irradiation in order to observe the mechanical dilation by the procedure. The femoral artery lumen was irradiated by a Helium-Cadmium(He-Cd) laser (wavelength; 325 nm) with 8 mW through the fiber during 30 s. We carried out that the laser irradiation produced vasorelaxation (185% on the average) compared with mechanical vasodilation (150% on the average) with angiography. The results suggest that intravascular transluminal irradiation with low-power UV laser might be applicable to the relief of acute arterial vasospasm.