Speckle tracking echocardiography for evaluation of myocardial functions before and after mitral valvuloplasty in dogs.

Background: Myxomatous mitral valve disease (MMVD) is the most common acquired heart disease in dogs. Mitral valvuloplasty (MVP) addresses regurgitation, but the pre- and postoperative changes in myocardial function remain uncertain.

Objectives: This study evaluated myocardial motion before and after MVP using two-dimensional speckle-tracking echocardiography (2D-STE).

Functional molecular models of photosynthesis.

This perspective focuses on functional models of photosynthesis to achieve molecular photocatalytic systems that mimic photosystems I and II (PSI and PSII). A long-lived and high-energy electron-transfer state of 9-mesityl-10-methylacridinium ion (Acr-Mes) has been attained as a simple and useful model of the photosynthetic reaction center. Acr-Mes has been used as an effective photoredox catalyst for photocatalytic hydrogen evolution and regioselective reduction of NAD(P) from plastoquinone analogs as a molecular functional model of PSI.

Identification, Characterization, and Electronic Structures of Interconvertible Cobalt-Oxygen TAML Intermediates.

The reaction of Li[(TAML)Co]·3HO (TAML = tetraamido macrocyclic tetraanionic ligand) with iodosylbenzene at 253 K in acetone in the presence of redox-innocent metal ions (Sc(OTf) and Y(OTf)) or triflic acid affords a blue species , which is converted reversibly to a green species upon cooling to 193 K. The electronic structures of and have been determined by combining advanced spectroscopic techniques (X-band electron paramagnetic resonance (EPR), electron nuclear double resonance (ENDOR), X-ray absorption spectroscopy/extended X-ray absorption fine structure (XAS/EXAFS), and magnetic circular dichroism (MCD)) with theoretical studies. Complex is best represented as an = 1/2 [(Sol)(TAML)Co---OH(LA)] species (LA = Lewis/Brønsted acid and Sol = solvent), where an = 1 Co(III) center is antiferromagnetically coupled to = 1/2 TAML, which represents a one-electron oxidized TAML ligand.

Scandium Ion-Promoted Electron-Transfer Disproportionation of 2-Phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-Oxide (PTIO) in Acetonitrile and Its Regeneration Induced by Water.

2-Phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide (PTIO), a persistent nitronyl nitroxide radical, has been used for the detection and trapping of nitric oxide, as a redox mediator for batteries, for the activity estimation of antioxidants, and so on. However, there is no report on the reactivity of PTIO in the presence of redox-inactive metal ions. In this study, it is demonstrated that the addition of scandium triflate, Sc(OTf) (OTf = OSOCF), to an acetonitrile (MeCN) solution of PTIO resulted in an electron-transfer disproportionation to generate the corresponding cation (PTIO) and anion (PTIO), the latter of which is suggested to be stabilized by Sc to form [(PTIO)Sc].

Photocatalytic CO Reduction Using an Osmium Complex as a Panchromatic Self-Photosensitized Catalyst: Utilization of Blue, Green, and Red Light.

The photocatalytic reduction of carbon dioxide (CO) represents an attractive approach for solar-energy storage and leads to the production of renewable fuels and valuable chemicals. Although some osmium (Os) photosensitizers absorb long wavelengths in the visible-light region, a self-photosensitized, mononuclear Os catalyst for red-light-driven CO reduction has not yet been exploited. Here, we discovered that the introduction of an Os metal to a PNNP-type tetradentate ligand resulted in the absorption of light with longer-wavelength (350-700 nm) and that can be applied to a panchromatic self-photosensitized catalyst for CO reduction to give mainly carbon monoxide (CO) with a total turnover number (TON) of 625 under photoirradiation (λ≥400 nm).

Artificial Photosynthesis for Regioselective Reduction of NAD(P) to NAD(P)H Using Water as an Electron and Proton Source.

In photosynthesis, four electrons and four protons taken from water in photosystem II (PSII) are used to reduce NAD(P) to produce NAD(P)H in photosystem I (PSI), which is the most important reductant to reduce CO. Despite extensive efforts to mimic photosynthesis, artificial photosynthesis to produce NAD(P)H using water electron and proton sources has yet to be achieved. Herein, we report the photocatalytic reduction of NAD(P) to NAD(P)H and its analogues in a molecular model of PSI, which is combined with water oxidation in a molecular model of PSII.

Water-Induced Regeneration of a 2,2-Diphenyl-1-picrylhydrazyl Radical after Its Scandium Ion-Promoted Electron-Transfer Disproportionation in an Aprotic Medium.

A neutral, stable radical, 2,2-diphenyl-1-picrylhydrazyl radical (DPPH), has been frequently used to estimate the activity of antioxidants for more than 60 years. However, the number of reports about the effect of metal ions on the reactivity of DPPH is quite limited. We have recently reported a unique electron-transfer disproportionation of DPPH to produce the DPPH cations (DPPH) and anions (DPPH) upon the addition of scandium triflate [Sc(OTf) (OTf = OSOCF)] to an acetonitrile (MeCN) solution of DPPH.

A Case of Nail Yellow Discoloration due to Topical Treatment of Onychomycosis with Luliconazole 5% Nail Solution.

A woman in her 70s had onychomycosis that was treated with topical luliconazole solution. Her nails changed color to yellow due to the treatment and exposure to sunlight. Avoidance of sunlight and continuous application of luliconazole resolved the discoloration and were effective for the treatment of onychomycosis one year after the first visit.

Redox catalysis photoinduced electron transfer.

This perspective article highlights redox catalysis of organic and inorganic molecules photoinduced electron transfer, which is well exploited for a number of important photoredox reactions including hydrogen evolution, water oxidation and a number of synthetic applications. Organic and inorganic photoredox catalysis is also combined with thermal transition metal redox catalysis to achieve overall photocatalytic redox reactions, which would otherwise not be possible by using photoredox catalysis or thermal redox catalysis alone. Both thermodynamic and kinetic data are discussed to understand the photoinduced electron-transfer processes of organic and inorganic photoredox catalysts in the light of the Marcus theory of electron transfer, providing a comprehensive and valuable guide for employing organic and inorganic redox catalysts photoinduced electron transfer.

Use of Singlet Oxygen in the Generation of a Mononuclear Nonheme Iron(IV)-Oxo Complex.

Nonheme iron(III)-superoxo intermediates are generated in the activation of dioxygen (O) by nonheme iron(II) complexes and then converted to iron(IV)-oxo species by reacting with hydrogen donor substrates with relatively weak C-H bonds. If singlet oxygen (O) with ca. 1 eV higher energy than the ground state triplet oxygen (O) is employed, iron(IV)-oxo complexes can be synthesized using hydrogen donor substrates with much stronger C-H bonds.

A Contrasting Effect of Acid in Electron Transfer, Oxygen Atom Transfer, and Hydrogen Atom Transfer Reactions of a Nickel(III) Complex.

There have been many examples of the accelerating effects of acids in electron transfer (ET), oxygen atom transfer (OAT), and hydrogen atom transfer (HAT) reactions. Herein, we report a contrasting effect of acids in the ET, OAT, and HAT reactions of a nickel(III) complex, [Ni(PaPy*)] () in acetone/CHCN (v/v 19:1). was synthesized by reacting [Ni(PaPy*)] () with magic blue or iodosylbenzene in the absence or presence of triflic acid (HOTf), respectively.

Surgical treatment for left atrial rupture due to myxomatous mitral valve disease in three dogs: A case report.

Introduction: Myxomatous mitral valve degeneration (MMVD) is an acquired heart disease which sometimes result in pulmonary oedema and left atrial rupture. In previous reports, left atrial rupture has been non-surgically controlled and its prognosis investigated. There is, however, no report concerning surgically treated left atrial rupture with mitral valvuloplasty and follow-up results.

Crucial Roles of a Pendant Imidazole Ligand of a Cobalt Porphyrin Complex in the Stoichiometric and Catalytic Reduction of Dioxygen.

A cobalt porphyrin complex with a pendant imidazole base ([(L )Co ]) is an efficient catalyst for the homogeneous catalytic two-electron reduction of dioxygen by 1,1'-dimethylferrocene (Me Fc) in the presence of triflic acid (HOTf), as compared with a cobalt porphyrin complex without a pendant imidazole base ([(L )Co ]). The pendant imidazole ligand plays a crucial role not only to provide an imidazolinium proton for proton-coupled electron transfer (PCET) from [(L )Co ] to O in the presence of HOTf but also to facilitate electron transfer (ET) from [(L )Co ] to O in the absence of HOTf. The kinetics analysis and the detection of intermediates in the stoichiometric and catalytic reduction of O have provided clues to clarify the crucial roles of the pendant imidazole ligand of [(L )Co ] for the first time.

Heme compound II models in chemoselectivity and disproportionation reactions.

Heme compound II models bearing electron-deficient and -rich porphyrins, [Fe(O)(TPFPP)(Cl)] (1a) and [Fe(O)(TMP)(Cl)] (2a), respectively, are synthesized, spectroscopically characterized, and investigated in chemoselectivity and disproportionation reactions using cyclohexene as a mechanistic probe. Interestingly, cyclohexene oxidation by 1a occurs at the allylic C-H bonds with a high kinetic isotope effect (KIE) of 41, yielding 2-cyclohexen-1-ol product; this chemoselectivity is the same as that of nonheme iron(iv)-oxo intermediates. In contrast, as observed in heme compound I models, 2a yields cyclohexene oxide product with a KIE of 1, demonstrating a preference for C[double bond, length as m-dash]C epoxidation.

Hemodynamic Effects of Protamine Infusion in Dogs with Myxomatous Mitral Valve Disease Undergoing Mitral Valvuloplasty.

Protamine, an antagonizing agent to heparin, is indispensable for dogs undergoing cardiopulmonary bypass. Protamine-induced hypotension (PIH) during cardiac anesthesia has been reported in humans. The purpose of this study was to describe the hemodynamic effect of protamine administration in dogs during cardiac surgery in clinical cases.

Acid Catalysis in the Oxidation of Substrates by Mononuclear Manganese(III)-Aqua Complexes.

Acids are known to enhance the reactivities of metal-oxygen intermediates, such as metal-oxo, -hydroperoxo, -peroxo, and -superoxo complexes, in biomimetic oxidation reactions. Although metal-aqua (and metal-hydroxo) complexes have been shown to be potent oxidants in oxidation reactions, acid effects on the reactivities of metal-aqua complexes have never been investigated previously. In this study, a mononuclear manganese(III)-aqua complex, [(dpaq)Mn(OH)] (; dpaq = 2-[bis(pyridin-2-ylmethyl)]amino--quinolin-8-ylacetamidate with an NO substituent at the 5 position), which is relatively stable in the presence of triflic acid (HOTf), is used in the investigation of acid-catalyzed oxidation reactions by metal-aqua complexes.

Molecular Photocatalytic Water Splitting by Mimicking Photosystems I and II.

In nature, water is oxidized by plastoquinone to evolve O and form plastoquinol in Photosystem II (PSII), whereas NADP is reduced by plastoquinol to produce NADPH and regenerate plastoquinone in Photosystem I (PSI), using homogeneous molecular photocatalysts. However, water splitting to evolve H and O in a 2:1 stoichiometric ratio has yet to be achieved using homogeneous molecular photocatalysts, remaining as one of the biggest challenges in science. Herein, we demonstrate overall water splitting to evolve H and O in a 2:1 ratio using a two liquid membranes system composed of two toluene phases, which are separated by a solvent mixture of water and trifluoroethanol (HO/TFE, 3:1 v/v), with a glass membrane to combine PSI and PSII molecular models.

Tunneling in the Hydrogen-Transfer Reaction from a Vitamin E Analog to an Inclusion Complex of 2,2-Diphenyl-1-picrylhydrazyl Radical with β-Cyclodextrin in an Aqueous Buffer Solution at Ambient Temperature.

Recently, increasing attention has been paid to quantum mechanical behavior in biology. In this study, we investigated the involvement of quantum mechanical tunneling in the hydrogen-transfer reaction from Trolox, a water-soluble analog of vitamin E (α-tocopherol), to 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) in a phosphate buffer solution (0.05 M, pH 7.

Enthalpy-Entropy Compensation Effect in Oxidation Reactions by Manganese(IV)-Oxo Porphyrins and Nonheme Iron(IV)-Oxo Models.

"Enthalpy-Entropy Compensation Effect" (EECE) is ubiquitous in chemical reactions; however, such an EECE has been rarely explored in biomimetic oxidation reactions. In this study, six manganese(IV)-oxo complexes bearing electron-rich and -deficient porphyrins are synthesized and investigated in various oxidation reactions, such as hydrogen atom transfer (HAT), oxygen atom transfer (OAT), and electron-transfer (ET) reactions. First, all of the six Mn(IV)-oxo porphyrins are highly reactive in the HAT, OAT, and ET reactions.

Deeper Understanding of Mononuclear Manganese(IV)-Oxo Binding Brønsted and Lewis Acids and the Manganese(IV)-Hydroxide Complex.

Binding of Lewis acidic metal ions and Brønsted acid at the metal-oxo group of high-valent metal-oxo complexes enhances their reactivities significantly in oxidation reactions. However, such a binding of Lewis acids and proton at the metal-oxo group has been questioned in several cases and remains to be clarified. Herein, we report the synthesis, characterization, and reactivity studies of a mononuclear manganese(IV)-oxo complex binding triflic acid, {[(dpaq)Mn(O)]-HOTf} (-HOTf).

Identifying Intermediates in Electrocatalytic Water Oxidation with a Manganese Corrole Complex.

Water nucleophilic attack (WNA) on high-valent terminal Mn-oxo species is proposed for O-O bond formation in natural and artificial water oxidation. Herein, we report an electrocatalytic water oxidation reaction with Mn tris(pentafluorophenyl)corrole () in propylene carbonate (PC). O was generated at the Mn potential with hydroxide, but a more anodic potential was required to evolve O with only water.

Effects of reaction environments on radical-scavenging mechanisms of ascorbic acid.

The effects of reaction environments on the radical-scavenging mechanisms of ascorbic acid (AscH) were investigated using 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) as a reactivity model of reactive oxygen species. Water-insoluble DPPH was solubilized by β-cyclodextrin (β-CD) in water. The DPPH-scavenging rate of AscH in methanol (MeOH) was much slower than that in phosphate buffer (0.

A Mononuclear Non-Heme Manganese(III)-Aqua Complex in Oxygen Atom Transfer Reactions via Electron Transfer.

Metal-oxygen complexes, such as metal-oxo [M(O)], -hydroxo [M(OH)], -peroxo [M(O)], -hydroperoxo [M(OOH)], and -superoxo [M(O)] species, are capable of conducting oxygen atom transfer (OAT) reactions with organic substrates, such as thioanisole (PhSMe) and triphenylphosphine (PhP). However, OAT of metal-aqua complexes, [M(OH)], has yet to be reported. We report herein OAT of a mononuclear non-heme Mn(III)-aqua complex, [(dpaq)Mn(OH)] (, dpaq = 2-[bis(pyridin-2-ylmethyl)]amino--quinolin-8-yl-acetamidate), to PhSMe and PhP derivatives for the first time; it is noted that no OAT occurs from the corresponding Mn(III)-hydroxo complex, [(dpaq)Mn(OH)] (), to the substrates.

Acid-promoted hydride transfer from an NADH analogue to a Cr(iii)-superoxo complex via a proton-coupled hydrogen atom transfer.

The sequential transfer of an electron, a proton and an electron in a hydride transfer from dihydronicotinamide adenine dinucleotide (NADH) and its analogues has never been separated well. In addition, the effect of acids on hydride transfer from an NADH analogue to a metal-superoxo species has yet to be reported. We report herein the first example of an acid-promoted hydride transfer from an NADH analogue, 10-methyl-9,10-dihydroacridine (AcrH), to a Cr(iii)-superoxo complex, [(TMC)Cr(O)], in the presence of HOTf in MeCN at 233 K.