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Objective: The Paris System for Reporting Urinary Cytology considered the nuclear-to-cytoplasmic (N:C) ratio as the most important cytomorphological feature for detecting high-grade urothelial carcinoma (HGUC) cells. Few quantitative studies have been conducted on other features although quantitative studies on the N:C ratio have been reported. Therefore, this study quantitatively analysed important cytomorphological features in distinguishing benign reactive cells from HGUC cells., Methods: We analysed 2866 cells from the urine of 52 patients. A digital image analyser was used to quantitatively measure the nuclear area, cell area, N:C ratio, and nuclear roundness for HGUC cells and benign reactive cells. Additionally, the diagnostic value of quantitative cytomorphological criteria in HGUC cells was evaluated by the receiver operating characteristic curve., Results: The area under the curve for the prediction of HGUC cells for all cells and the top five cells was in the following order: nuclear area (0.920 and 0.992, respectively), N:C ratio (0.849 and 0.977), cell area (0.781 and 0.920), and nuclear roundness (0.624 and 0.605). The best cutoff value of the N:C ratio to differentiate HGUC cells from benign reactive cells was 0.438, and using the N:C ratio of 0.702, the positive predictive value obtained was 100%., Conclusions: Our study indicated that nuclear area is a more important cytomorphological criterion than the N:C ratio for HGUC cell detection. Moreover, extracted data of the top five cells were more valuable than the data of all cells, which can be helpful in the routine practice and future criteria definition in urine cytology., (© 2023 John Wiley & Sons Ltd.)

The development of anion sensors for selective detection of a specific anion is a crucial research topic. We previously reported a selective photo-induced colorimetric reaction of 1-methyl-3-( N -(1,8-naphthalimidyl)ethyl)imidazolium (MNEI) having a cationic receptor in the presence of molecules having multiple carboxy groups, such as succinate, citrate, and polyacrylate. However, the mechanism underlying this reaction was not clarified. Here, we investigate the photo-induced colorimetric reaction of N -[2-(trimethylammonium)ethyl]-1,8-naphthalimide (TENI), which has a different cationic receptor from MNEI and undergoes the photo-induced colorimetric reaction, and its analogues to clarify the reaction mechanism. The TENI analogues having substituents on the naphthalene ring provide important evidence, suggesting that the colorimetric chemical species were radical anions generated via photo-induced electron transfer from carboxylate to the naphthalimide derivative. The generation of the naphthalimide-based radical anion is verified by 1 H NMR and cyclic voltammetry analyses, and photo-reduction of methylene blue is mediated by TENI. In addition, the role of the cationic receptor for the photo-induced colorimetric reaction is investigated with TENI analogues having different hydrophilic groups instead of the trimethylammonium group. Interestingly, the photo-induced colorimetric reaction is observed in a nonionic analogue having a polyethylene glycol group, indicating that the colorimetric reaction does not require a cationic receptor. On the other hand, we reveal that the trimethylammonium group stabilizes the radical anion species. These generation and stabilization phenomena of naphthalimide-based radical anion species will contribute to the development of sophisticated detection systems specific for carboxylate., Competing Interests: The authors declare no competing financial interest., (© 2021 The Authors. Published by American Chemical Society.)

We have evaluated the strength of intramolecular hydrogen bond in a protein based on molecular dynamics and quantum chemical calculation. To estimate the intramolecular hydrogen bond strength in okadaic acid (OA), we analyzed the influence of solvent and protonation states on the hydrogen bond and the entire structure. We performed molecular dynamics calculation and analyzed the strength of the hydrogen bond by measuring bond length and bond angle. The stable structure differs depending on the kind of solvent used and the protonation state of OA. Using the mean interaction energy from the quantum chemical calculation, hydrogen bond length and angle were investigated against bond energy. Although dielectric constant slightly depends on bond energy, the estimation of the intramolecular hydrogen bond strength in OA is possible even in a protein environment. The Coulomb interaction between OA and surrounding arginine produced a more negatively charged O1 in OA. The hydrogen bond energy in the deprotonated state is larger than that in the protonated state.

1-Methyl-3-(N-(1,8-naphthalimidyl)ethyl)imidazolium (MNEI) has potential as a versatile sensor that can measure the electronegativity of anions based on the fluorescence intensity upon irradiation. To clarify the factors that determine the fluorescence intensity, constrained density functional theory (CDFT) was applied to explore the electron transfer (ET) states of MNEI halide species (MNEI-X; X = F, Cl, Br, I). According to the CDFT potential energy surface, intra-molecular ET (S M1 ) states on MNEI are responsible for the intensity of absorption and fluorescence spectra. However, inter-molecular ET (S ET ) states between MNEI and X are certainly responsible for fluorescence quenching. Hence, the energetic difference between the S M1 state and the S ET state (ΔE M1_ET ) is a crucial factor that determines the fluorescence intensity in the spectra of MNEI-X complexes. ΔE M1_ET decreases as the electronegativity of X decreases (i.e., F > Cl > Br > I). This explains the fluorescence intensity of MNEI-X.

We have investigated the dependencies of various computational methods in the calculation of acid dissociation constants (pK a values) of certain chemical groups found in protonatable amino acids based on our previous scheme [ Matsui ; Phys. Chem. Chem. Phys. 2012 , 14 , 4181 - 4187 ]. By changing the quantum chemical (QC) method (Hartree-Fock (HF) and perturbation theory, and composite methods, or exchange-correlation functionals in density functional theory (DFT)), basis sets, solvation models, and the cavities used in the solvent models, we have exhaustively tested about 2,200 combinations to find the best combination for pK a estimation among them. Of the tested parameters, the choice of the basis set and cavity is the most crucial to reproduce experimental values compared to other factors. Concerning the basis set, the inclusion of diffuse functions is quite important for carboxyl, thiol, and phenol groups judging from the mean absolute errors (MAEs) measured from the experimental values. Of the cavity models, between the Pauling, Klamt, and the universal force field (UFF) definitions, the UFF defined cavity is the best choice, resulting in the smallest MAEs. Concerning the QC methods, hybrid DFTs and range-separated DFTs always provide better results than pure DFTs and HF. As a result, we found that LC-ϖPBE/6-31+G(d) with PCM-SMD/UFF provides the best pK a estimation with a MAE within 0.15 pK a units.

Electron transfer (ET) states of 1-methyl-3-(N-(1,8-naphthalimidyl)ethyl)imidazolium iodide are responsible for its photophysics. Investigation of an ET state based on constrained density functional theory (CDFT) revealed that nonradiative decay from the ET excited state is mediated by the interaction of the iodine atom with the 1,8-naphthalimide or the imidazolium group.

Poly-paraphenylenevinylene (PPV), a material used in organic light-emitting diodes (OLEDs), for which improving the efficiency is an important issue. In general, the molecular orientations of organic compounds in the crystal form are an essential factor determining electron and hole transfer, which are closely related to the efficiency of OLEDs. We have investigated the effects of the rotation of each molecule and the intermolecular distance in the dimer system of PPV, which consists of donor and acceptor molecules, on its charge-recombination process by performing constrained density functional calculations. Starting from the structure of the crystal, it was clarified that the rotation of the donor decreases the charge-recombination factor, to nearly zero, while that of the acceptor increases it to about 10(6) s(-1). We found that this is caused by the repulsive interaction between the donor and acceptor molecules and the formation of a transport pathway resulting from the acceptor rotation.

We have designed a novel 1,8-naphthalimide derivative with an open space for an anion. Computational calculation has predicted that the space could trap various anion species and photo-induced charge transfer depending on the anion's electrophilic properties. Indeed, the fluorescence behaviour of the 1,8-naphthalimide derivative complexes with each anion is consistent with the computational prediction.

Singlet-oxygen [O2((1)Δg)] generation by valence-excited thiophene (TPH) has been investigated using multireference Møller-Plesset second-order perturbation (MRMP2) theory of geometries optimized at the complete active space self-consistent field (CASSCF) theory level. Our results indicate that triplet TPH(1(3)B2) is produced via photoinduced singlet TPH(2(1)A1) because 2(1)A1 TPH shows a large spin-orbit coupling constant with the first triplet excited state (1(3)B2). The relaxed TPH in the 1(3)B2 state can form an exciplex with O2((3)Σg(-)) because this exciplex is energetically more stable than the relaxed TPH. The formation of the TPH(1(3)B2) exciplex with O2((3)Σg(-)) whose total spin multiplicity is triplet (T1 state) increases the likelihood of transition from the T1 state to the singlet ground or first excited singlet state. After the transition, O2((1)Δg) is emitted easily although the favorable product is that from a 2 + 4 cycloaddition reaction.

Functional regulation of myoglobin (Mb) is thought to be achieved through the heme environment furnished by nearby amino acid residues, and subtle tuning of the intrinsic heme Fe reactivity. We have performed substitution of strongly electron-withdrawing perfluoromethyl (CF(3)) group(s) as heme side chain(s) of Mb to obtain large alterations of the heme electronic structure in order to elucidate the relationship between the O(2) affinity of Mb and the electronic properties of heme peripheral side chains. We have utilized the equilibrium constant (pK(a)) of the "acid-alkaline transition" in metmyoglobin in order to quantitatively assess the effects of the CF(3) substitutions for the electron density of heme Fe atom (rho(Fe)) of the protein. The pK(a) value of the protein was found to decrease by approximately 1 pH unit upon the introduction of one CF(3) group, and the decrease in the pK(a) value with decreasing the rho(Fe) value was confirmed by density functional theory calculations on some model compounds. The O(2) affinity of Mb was found to correlate well with the pK(a) value in such a manner that the P(50) value, which is the partial pressure of O(2) required to achieve 50% oxygenation, increases by a factor of 2.7 with a decrease of 1 pK(a) unit. Kinetic studies on the proteins revealed that the decrease in O(2) affinity upon the introduction of an electron-withdrawing CF(3) group is due to an increase in the O(2) dissociation rate. Since the introduction of a CF(3) group substitution is thought to prevent further Fe(2+)-O(2) bond polarization and hence formation of a putative Fe(3+)-O(2)(-)-like species of the oxy form of the protein [Maxwell, J. C.; Volpe, J. A.; Barlow, C. H.; Caughey, W. S. Biochem. Biophys. Res. Commun. 1974, 58, 166-171], the O(2) dissociation is expected to be enhanced by the substitution of electron-withdrawing groups as heme side chains. We also found that, in sharp contrast to the case of the O(2) binding to the protein, the CO association and dissociation rates are essentially independent of the rho(Fe) value. As a result, the introduction of electron-withdrawing group(s) enhances the preferential binding of CO to the protein over that of O(2). These findings not only resolve the long-standing issue of the mechanism underlying the subtle tuning of the intrinsic heme Fe reactivity, but also provide new insights into the structure-function relationship of the protein.