Recently, long-lived, organic radical species have attracted much attention from chemists and material scientists because of their unique electronic properties derived from their magnetic spin and ...singly occupied molecular orbitals. Most stable and persistent organic radicals are heteroatom-centered radicals, whereas carbon-centered radicals are generally very reactive and therefore have had limited applications. Because the physical properties of carbon-centered radicals depend predominantly on the topology of the π-electron array, the development of new carbon-centered radicals is key to new basic molecular skeletons that promise novel and diverse applications of spin materials. This account summarizes our recent studies on the development of novel carbon-centered radicals, including phenalenyl, fluorenyl, and triarylmethyl radicals.
Abstract Background The detailed mechanism of plaque stabilization by statin therapy is not fully understood. Objectives The aim of this study was to assess the effect of lipid-lowering therapy with ...20 mg/day of atorvastatin versus 5 mg/day of atorvastatin on fibrous cap thickness in coronary atherosclerotic plaques by using optical coherence tomography (OCT). Methods Seventy patients with unstable angina pectoris and untreated dyslipidemia were randomized to either 20 mg/day or 5 mg/day of atorvastatin therapy. OCT was performed to assess intermediate nonculprit lesions at baseline and 12-month follow-up. Results Serum low-density lipoprotein cholesterol level was significantly lower during therapy with 20 mg/day compared with 5 mg/day of atorvastatin (69 mg/dl vs. 78 mg/dl; p = 0.039). The increase in fibrous cap thickness was significantly greater with 20 mg/day compared with 5 mg/day of atorvastatin (69% vs. 17%; p < 0.001). The increase in fibrous cap thickness correlated with the decrease in serum levels of low-density lipoprotein cholesterol (R = −0.450; p < 0.001), malondialdehyde-modified low-density lipoprotein (R = −0.283; p = 0.029), high-sensitivity C-reactive protein (R = −0.276; p = 0.033), and matrix metalloproteinase-9 (R = −0.502; p < 0.001), and the decrease in grade of OCT-derived macrophages (R = −0.415; p = 0.003). Conclusions Atorvastatin therapy at 20 mg/day provided a greater increase in fibrous cap thickness in coronary plaques compared with 5 mg/day of atorvastatin. The increase of fibrous cap was associated with the decrease in serum atherogenic lipoproteins and inflammatory biomarkers during atorvastatin therapy. (Effect of Atorvastatin Therapy on Fibrous Cap Thickness in Coronary Atherosclerotic Plaque as Assessed by Optical Coherence Tomography: The EASY-FIT Study; NCT00700037 )
In this study, we developed a simultaneous measurement system for measuring the concentration fluctuations of three species by the light absorption spectrometric method using pulsed laser diodes. The ...conventional method utilizes halogen lamps or continuous laser diodes as light sources for concentration measurements. These light sources require multi-monochromators or dichroic mirrors, which makes these methods rather expensive. However, pulsed laser diodes as the light sources eliminate the need for additional multi-monochromators and dichroic mirrors. A diffusion field consisting of three dye species in an axisymmetric turbulent jet was measured using the developed concentration measurement system. To ascertain the validity of our concentration measurements, we compared the present measurement results with those of a single dye species and previous studies. It was observed that the concentrations of the three dye species were measured accurately by the present measuring system. Therefore, such low-cost concentration measurement systems can be developed and applied in various simultaneous measurements of concentration fluctuations of multiple species such as in turbulent reactive flows.
The synthesis of persistent, neutral organic radicals is challenging because of their inherent reactivities. Herein, we report the synthesis and characterization of a highly congested ...mesityl‐substituted tri(9‐anthryl)methyl (TAntM) radical (1). The scaffold was successfully synthesized by circumventing the steric hindrance imposed by the bulky groups surrounding the central methyl carbon atom. The radical has a threefold propeller structure, and the unpaired electron is mainly localized on the central carbon atom. Owing to its congested structure, 1 is remarkably stable, which facilitated handling under ambient conditions. Evaluation of the dynamic behavior of the TAntM scaffold indicated that the stability is due to the bulky anthryl units and the mesityl substituents. Because of its high persistence, wide‐range absorption, and good reversible redox properties, 1 has promising applications in organic devices.
A highly congested tri(9‐anthryl)methyl radical was successfully synthesized by circumventing the steric hindrance imposed by the bulky groups surrounding the central methyl carbon atom. Owing to its congested structure, the mesityl‐substituted tri(9‐anthryl)methyl radical is remarkably stable, which facilitates its handling under ambient conditions.
We prepared a new overcrowded tristricyclic aromatic ene (TAE) and investigated its external stimuli-responsive behavior for the switching between a closed-shell folded form and an open-shell twisted ...form. Upon photoirradiation, the folded form transforms into the biradical twisted form, whereas by keeping the twisted form in the dark, the reverse reaction gradually occurs at room temperature. This switchable conformational change is analyzed by means of UV–vis and electron spin resonance spectroscopies, cyclic voltammetry, density functional theory calculations, and kinetic studies.
For several decades, most physicians have believed that acute coronary syndrome (ACS) is caused by coronary thrombosis resulting from rupture of vulnerable plaque characterized by a thin fibrous cap ...overlying a large necrotic core and massive inflammatory cell infiltration. However, nearly one-third of ACS cases are caused by plaque erosion characterized by intact fibrous cap, less or absent necrotic core, less inflammation, and large lumen. Because of the limitations of current imaging modalities, including angiography and intravascular ultrasound, the importance of plaque erosion as a cause of acute coronary events is less well known. Optical coherence tomography (OCT) as an emerging modality with extremely high resolution is the only intravascular imaging modality available for identification of plaque erosion in vivo, which provides new insight into the mechanism of ACS. More importantly, the introduction of OCT to clinical practice enables us to differentiate the patients with ACS caused by plaque erosion from those caused by plaque rupture, thereby providing precise and personalized therapy based on the different underlying mechanisms. We systematically review the morphological characteristics of plaque erosion identified by OCT and its implications for the management of ACS.
The aim of this study was to assess agreement between optical coherence tomography (OCT) and histopathology for healed coronary plaques (HCPs) in human coronary arteries ex vivo, and to evaluate the ...prevalence and characteristics of HCPs in vivo.
Ex vivo OCT images were co-registered with histopathology in 144 cross-sections with ≥50% stenosis. Of these, 30 randomly selected pairs were employed to define morphological features of OCT for HCPs (OCT-derived HCPs); the remaining 114 pairs were used to evaluate the accuracy of OCT in detecting histologically-defined HCPs. In a clinical study, 60 target lesions from 60 patients with stable ischemic heart disease were divided into 2 groups according to the presence or absence of OCT-derived HCPs. Plaque characteristics were compared between the two groups.
In the autopsy study, an OCT-derived HCP was defined as a plaque with heterogeneous signal-rich layers of different optical signal density. The sensitivity, specificity, positive predictive value, and negative predictive value of OCT-derived HCP to detect histologically-defined HCPs were 81%, 98%, 93%, and 93%, respectively. In the clinical study, 46 (77%) had OCT-derived HCPs. Both microvessels and macrophages were more frequently identified in OCT-derived HCPs compared to their counterparts (43% vs. 0%; p<0.01, 70% vs. 21%; p<0.01, respectively).
An ex vivo OCT image has a good agreement with histology for HCPs detection. HCPs were frequently identified by OCT in target lesions in stable ischemic heart disease patients. OCT may be a useful intracoronary imaging for HCPs detection in vivo.
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•Despite histopathological evidence, there is a lack of the definition in vivo characterizing healed coronary plaques (HCPs).•In a validation study, an ex vivo optical coherence tomography (OCT) image has a good agreement with histology for the detection of HCPs.•In a clinical study, HCPs were not infrequently identified by OCT in vivo in stable ischemic heart disease patients.
The synthesis of phenalenyl‐endcapped 5cumulene as a cumulene‐based singlet biradical and the spin correlation changes of one‐dimensional aggregates are described. The high propensity for ...self‐aggregation of phenalenyl rings and the introduction of bulky substituents into the appropriate positions led to the formation of a one‐dimensional chain assembly. Single‐crystal X‐ray structural analysis indicated that the bond length alternation of the cumulene chain increased with decreasing temperature, along with improved overlapping of the phenalenyl rings. Variable‐temperature Raman spectroscopy and magnetic susceptibility measurements revealed that a localized spin pair within the molecule decouples at low temperatures, and a continuum spin system involving intra‐ and intermolecular spin–spin interactions emerges in the one‐dimensional chain.
A singlet biradical based on 5cumulene end‐capped with phenalenyl moieties was synthesized. The strong π–π stacking tendency of phenalenyl units led to controlled self‐assembly, with the formation of one‐dimensional chain assemblies. Variable‐temperature structural and Raman spectroscopic studies demonstrated that intramolecular spin pairs forming cumulene bonds coupled intermolecularly to form a continuum spin system at low temperatures (see picture).
Background:Acute myocardial infarction (AMI) is caused by coronary plaque rupture (PR), plaque erosion (PE), or calcified nodule (CN). We used optical coherence tomography (OCT) to compare stent ...expansion immediately after primary percutaneous coronary intervention (PCI) in patients with AMI caused by PR, PE, or CN.Methods and Results:In all, 288 AMI patients were assessed by OCT before and immediately after PCI, performed with OCT guidance according to OPINION criteria for stent sizing and optimization. The frequency of OCT-identified PR (OCT-PR), OCT-PE, and OCT-CN was 172 (60%), 82 (28%), and 34 (12%), respectively. Minimum stent area was smallest in the OCT-CN group, followed by the OCT-PE and OCT-PR groups (mean ±SD 5.20±1.77, 5.44±1.78, and 6.44±2.2 mm2, respectively; P<0.001), as was the stent expansion index (76±13%, 86±14%, and 87±16%, respectively; P=0.001). The frequency of stent malapposition was highest in the OCT-CN group, followed by the OCT-PR and OCT-PE groups (71%, 38%, and 27%, respectively; P<0.001), as was the frequency of stent edge dissection in the proximal reference (44%, 23%, and 10%, respectively; P<0.001). The frequency of tissue protrusion was highest in the OCT-PR group, followed by the OCT-PE and OCT-CN groups (95%, 88%, and 85%, respectively; P=0.036).Conclusions:Stent expansion was smallest in the OCT-CN group, followed by the OCT-PR and OCT-PE groups. Plaque morphology in AMI culprit lesions may affect stent expansion immediately after primary PCI.
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