Radical Caging Strategy for Cholinergic Optopharmacology.

Photo-caged methodologies have been indispensable for elucidating the functional mechanisms of pharmacologically active molecules at the cellular level. A photo-triggered removable unit enables control of the photo-induced expression of pharmacologically active molecular function, resulting in a rapid increase in the concentration of the bioactive compound near the target cell. However, caging the target bioactive compound generally requires specific heteroatom-based functional groups, limiting the types of molecular structures that can be caged. We have developed an unprecedented methodology for caging/uncaging on carbon atoms using a unit with a photo-cleavable carbon-boron bond. The caging/uncaging process requires installation of the CH2-B group on the nitrogen atom that formally assembles an N-methyl group protected with a photoremovable unit. N-Methylation proceeds by photoirradiation via carbon-centered radical generation. Using this radical caging strategy to cage previously uncageable bioactive molecules, we have photocaged molecules with no general labeling sites, including acetylcholine, an endogenous neurotransmitter. Caged acetylcholine provides an unconventional tool for optopharmacology to clarify neuronal mechanisms on the basis of photo-regulating acetylcholine localization. We demonstrated the utility of this probe by monitoring uncaging in HEK cells expressing a biosensor to detect ACh on the cell surface, as well as Ca2+ imaging in Drosophila brain cells (ex vivo).

Venous Hypertension Improved by a Viabahn Stent Graft Blocking Regurgitation to the Periphery of the Basilic Vein in an Elderly Patient Undergoing Hemodialysis: A Case Report.

Although necessary for hemodialysis (HD), arteriovenous grafts (AVG) frequently cause complications. Stenosis resulting in venous hypertension is a concern for physicians. Herein, we describe how venous hypertension was improved by using a Viabahn stent graft in an elderly HD patient. An 86-year-old woman started maintenance HD with a left-arm AVG. Two years later, she was referred to our hospital for treatment of juxta-graft-venous junction (GVJ) stenosis. Because of recurrence of stenosis at the juxta-GVJ, she underwent four percutaneous transluminal angioplasty (PTA) procedures during a period of 9 months. One month after the most recent PTA, the patient had redness, swelling, and pain in her left forearm. Venous hypertension was diagnosed on the basis of angiography findings showing regurgitation to the periphery of the basilic vein and juxta-GVJ stenosis. The stenosed juxta-GVJ was adequately expanded with a 7-mm balloon, and a 7-mm stent graft was inserted into the stenosis site. After successful treatment, there was no regurgitation to the periphery of the basilic vein and no symptoms. This complication should be considered when an AVG is created, because cutting off peripheral veins might prevent venous hypertension. Clinicians should perform regular postoperative monitoring.

Method to Improve Azo-Compound (AAPH)-Induced Hemolysis of Erythrocytes for Assessing Antioxidant Activity of Lipophilic Compounds.

We examined the method of oxidative hemolysis for assessment of antioxidant activity of various compounds, especially lipophilic compounds. 2,2'-Azobis(amidinopropane) dihydrochloride (AAPH) was used as the source of free radicals for the oxidative hemolysis of horse erythrocytes. We found that absorbance at 540 nm is not appropriate for monitoring AAPH-induced hemolysis. Instead, we should use absorbance at 523 nm (an isosbestic point), because AAPH oxidizes the oxygenated hemoglobin to methemoglobin and absorbance at 540 nm does not correctly reflect the amount of released hemoglobin by AAPH-induced hemolysis. The corrected method of AAPH-induced hemolysis was applicable to assess the antioxidant activity of various hydrophilic compounds such as ascorbic acid, (-)-epicatechin, and edaravone. For the assessment of antioxidant activity of lipophilic compounds, we need appropriate dispersing agents for these lipophilic compounds. Among several agents tested, 1,2-dimiristoyl-sn-glycero-3-phosphocholine (DMPC) liposome at a concentration of 0.34 mM was found to be useful. Exogenous α-tocopherol incorporated using DMPC liposome as a dispersing agent was shown to protect erythrocytes from AAPH-induced hemolysis in a concentration-dependent manner.