Dynamic covalently bonded rotaxanes cross-linked by imine bonds between the axle and ring: inverse temperature dependence of subunit mobility.
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Journal Article↗
Biomedical subjects
Takanori Suzuki
Publications and source records attributed to Takanori Suzuki.
Stereospecific change in conformation upon complexation of an exoditopic tetraamide host with a bis(ammonium) guest: chiral recognition and strong CD signaling.
Upon complexation of a rectangular-shaped achiral macrocyclic host with chiral guests, twisting deformation occurs to induce exciton-type bisignated CD, whereas a chiral rectangular host undergoes a similar structural change only with the matching enantiomer of a chiral guest.
Amides↗
Isolation and low-temperature x-ray analysis of intramolecular triarylmethane-triarylmethylium complex: preference for a C-H-bridged unsymmetric structure exhibiting a facile 1,5-hydride shift and charge-transfer interaction.
The intramolecular triarylmethane-methylium complex with an averaged C2v-symmetry was successfully generated by N-methylation of the acridine-acridan hybrid. Theoretical calculation and VT-NMR analyses in solution indicate the unsymmetric geometry for the three-center bond, which was finally confirmed crystallographically. Significant degree of CT interaction is induced through the very short C-H...C+ contact.
Journal Article↗
Tetracyanoanthraquinodimethanes with a chiral amide group: preparation, properties, and charge-transfer photochirogenetic reaction with 1,2-dianisylacenaphthene-1,2-diol.
[reaction: see text] A series of butterfly-shaped tetracyanoanthraquinodimethanes (TCNAQs) with a chiral amide auxiliary 1a-f were prepared from the corresponding anthraquinones. They are stronger acceptors than the unsubstituted derivative and undergo one-wave two-electron reduction. They form weak electron-donor-acceptor (EDA) complexes with the title pinacol 2. Upon charge-transfer excitation of these complexes, dihydro-TCNAQs 3 and 1,8-dianisoylnaphthalene 4 were efficiently formed, the latter of which is the product of a retropinacol reaction via 2+*. Partial enantiodifferentiation of rac-2 was realized during the photoreactions with 2-[(R)-1-phenylethylcarbamoyl]-TCNAQ 1ain CD3CN. Thus, optically active (S,S)-(+)-pinacol 2 (12.3% ee at 54% conversion; 21.5% ee at 70% conversion) was recovered from the photolyzates. This reaction represents a new and rare example of the pseudokinetic resolution of tert-alcohol accompanied by C-C bond fission. Significant differences in the association constants for the diastereomeric EDA complexes are responsible for the observed enantiodifferentiation.
Journal Article↗
Butane-1,4-diyl dications stabilized by steric factors: electrochiroptical response systems based on reversible interconversion between dihydro[5]helicene-type electron acceptors and electron-donating 1,1'-binaphthyls.
Incorporation in the dihydro[5]helicene framework prevents deprotonation of the title dications by steric factors, thus allowing their isolation as deeply colored stable salts. Based on the reversible interconversion with the electron-donating binaphthylic diolefins, they constitute a new class of electrochromic systems, in which C-C bond making/breaking is accompanied by two-electron transfer. Optically pure (R)-binaphthylic donors are interconvertible with the 1,4-dications with the R,R-configuration. The very large molar ellipticity makes it possible for them to be used as electrochiroptical response systems, by which the electrochemical input is transduced into two spectral outputs, i.e. UV-Vis and circular dichroism. Structurally related push-pull-type bis(quinonemethide)s also exhibit a similar multi-output electrochemical response.
Journal Article↗
Multipoint recognition of catecholamines by hydrindacene-based receptors accompanied by the complexation-induced conformational switching.
The molecular recognition of catecholamines by hydrindacene-based receptors 1 and 2, as well as the durene-based receptor 3, and the guest-induced conformational changes are reported. These receptors selectively bind adrenaline and dopamine salts through the guests' ammonium group and 3-hydroxyl group on the aromatic ring. In the case of adrenaline, an additional hydrogen bond with a benzylic hydroxyl group is formed. In 2 % CD3CN/CDCl3, the association constants are of the order of 10(4) M(-1), which is much larger than with guests without the 3-hydroxyl groups (10(3) M(-1)). The two amide groups of receptor 1 can rotate freely around the C(aromatic)--C(amide) bond, whereas the tert-amide in 2 changes between two stable conformations at a slow enough rate to allow detection by (1)H NMR spectroscopy. In the absence of a guest molecule, the syn-conformer is less stable than the anti-conformer. On complex formation with adrenaline, the syn-conformer becomes dominant due to an intramolecular dipole-reversal effect in addition to multipoint hydrogen bonding.
Binding Sites↗
First stable 7,7,8,8-tetraaryl-o-quinodimethane: isolation, X-ray structure, electrochromic response of 9,10-bis(dianisylmethylene)-9,10-dihydrophenanthrene.
Oxidative cyclization of 2,2'-bis(dianisylethenyl)biphenyl yielded the dicationic salt of phenanthrene-9,10-diylbis(dianisylmethylium), which in turn afforded the severely congested title molecule as the first stable tetraaryl-o-quinodimethane derivative upon reduction.
Journal Article↗
Kinetic stabilization of the o-quinoidal 3,4-benzotropone system.
Kinetic stabilization of the o-quinoidal 3,4-benzotropone system was investigated. The parent 3,4-benzotropone undergoes rapid [pi8 + pi10] dimerization in fluid solution even at -78 degree C while triptycene-fused derivative having a tert-butyl group at the C6 position of the tropone moiety was found to be stable indefinitely under similar conditions. The relative importance of the triptycene moiety and the tert-butyl group in for the kinetic stabilization was evaluated.
Cycloheptanes↗
Positive homotropic allosteric binding of benzenediols in a hydrindacene-based exoditopic receptor: cooperativity in amide hydrogen bonding.
The preparation and complexation properties of a hydrindacene-based exoditopic receptor, that exhibits a positive homotropic allosteric binding process toward benzenediols, are described. The exoditopic receptors form 1:2 complexes with resorcinols, catechol, and 3-hydroxybenzyl alcohol with K2/K1 = 3-33. Both the entropy and the enthalpy terms are important in this allosteric system; the crystallographic studies provide the first clear evidence that the cooperativity in amide hydrogen bonding by polarization contributes to the positive homotropic allosteric binding property.
Allosteric Regulation↗
Pi-extended o-quinoidal tropone derivatives: experimental and theoretical studies of naphtho[2,3-c]tropone and anthro[2,3-c]tropone.
pi-Extended o-quinoidal tropone derivatives, naphtho[2,3-c]tropone (3) and anthro[2,3-c]tropone (4), have been investigated theoretically as well as experimentally. The geometrical optimization of 3,4 and related compounds at the B3LYP level employing 6-31G* basis set as well as the GIAO calculations at the RHF level employing the 6-31+G* basis set have been performed to evaluate the contributions of the polarized resonance forms to these molecules. The GIAO calculated NICS(1) values indicate that the aromaticities of the tropone rings of o-quinoidal 3 and 4 are significantly increased as compared with that of parent tropone (1) at the expense of the fused benzenoid rings, consistent with the significant electronic polarization of these molecules in the ground state. On the other hand, the fusion of a benzene or naphthalene ring to the 2,3- or 4,5-position of tropone leads to diminution of aromaticity in the resulting tropone moiety. Experimentally, irradiation of 6,7-(2',3'-naphtho)bicyclo[3.2.0]hepta-3,6-dien-2-one (10) in a rigid glass at -196 degrees C leads to the formation of, which exhibits a characteristic UV-Vis absorption extending to 700 nm and undergoes rapid [pi 12 + pi 14] dimerization upon thawing the glass. In contrast, 6,7-(2',3'-anthro)bicyclo[3.2.0]hepta-3,6-dien-2-one (11) showed no sign of isomerization to 4 under the same reaction conditions.
Journal Article↗
Incidence of bladder cancer discovered by urethrocystoscopy at prostate biopsy: extraordinary high incidence of tiny bladder cancer in elderly males.
In order to clarify the incidence of bladder cancer with and without prostate cancer, we investigated bladder cancer discovered incidentally by urethrocystoscopy at prostate biopsy. Between April 1997 and December 2003, 498 patients who were suspected prostate cancer were performed prostate biopsy and urethrocystoscopy simultaneously. We investigate possible invasion of prostate cancer into the urethra or bladder mucosa as well as bladder cancer, including other benign lesions of the bladder by urethrocystoscopy. Prostate cancer was confirmed in 175 (35.1%) of the 498 patients histologically, and bladder cancer was discovered incidentally in 12 patients (2.4 %). The incidence of bladder cancer in patients with prostate cancer of 2.3% (4/175) was not significantly different from that in patients without prostate cancer, which was 2.5% (8/323). Superficial and those with a size less than 1 cm were noted in 11 patients (92%) and 10 patients (83%) respectively. High incidence rate of bladder cancer with prostate cancer was reported previously, however, there was no study to compare the incidence rate of bladder cancer between cases with and without prostate cancer. The present study suggests that asymptomatic tiny bladder cancer may be present at an unexpectedly high incidence rate in elderly males.
Adult↗
Electrochiroptical response of 2,2'-(2,2-diarylethenyl)binaphthyl-type electron donors that undergo reversible C-C bond formation/breaking upon two-electron transfer.
2,2'-[2,2-Bis(4-dimethylaminophenyl)ethenyl]biphenyl (1) is a strong electron donor that undergoes oxidative C-C bond formation to give a stable dication rac-2(2+), the 9,10-dihydrophenanthrene derivative substituted with two bis(4-dimethylaminophenyl)methylium chromophores. This dication salt regenerates the starting diolefin 1 by reductive C-C bond breaking, thus realizing a new electrochromic system with high electrochemical bistability and a vivid change in color from yellow to deep blue. Similarly, the binaphthylic diolefin rac-3 and the helicene-type dication rac-4(2+) are interconvertible upon two-electron transfer. Both the UV-vis and CD spectra changed drastically upon electrochemical transformation between optically pure 3 and 4(2+), which represents a new electrochiroptical system.
Journal Article↗
Functionalization and kinetic stabilization of the [4]paracyclophane system and aromaticity of its extremely bent benzene ring.
Kinetic stabilization of the [4]paracyclophane skeleton by the introduction of substituents, which serve to sterically hinder reactions at the reactive bridgehead sites, and properties of the resultant [4]paracyclophanes are investigated in this study. Modification of the property of [4]paracyclophane by functionalization is also intended. [4]Paracyclophanes are designed to be derived from the corresponding Dewar benzene isomers via their photochemical aromatization, and the requisite 1,4-bridged Dewar benzenes bearing sterically demanding functional groups are prepared. Irradiation of these precursors under matrix isolation at 77 K leads to the formation of [4]paracyclophanes, which exhibit characteristic electronic absorption spectra. The half-lives of the generated species vary widely from less than 1 min at -90 degrees C to 0.5 h at -20 degrees C, depending on the type of substituents and the pattern of substitution. One of the derivatives, 24, is stable enough and its content in the irradiated mixture is high enough to permit the measurement of the (1)H NMR spectrum. The recorded spectrum, which is reproduced very well by theoretical calculations using the GIAO method at the hybrid HF-DFT (B3LYP/6-31+G*) level, suggests the sustenance of rather strong diatropicity in its severely bent benzene moiety. Calculations on the bent benzene whose geometry is constrained to that calculated for 24 support that aromaticity is retained to a significant extent as compared to that of planar benzene, as judged by the magnetic criteria of aromaticity, that is, diamagnetic susceptibility exaltation and nucleus-independent chemical shift. The reason for the retention of aromaticity despite the severe bending of the benzene ring is discussed. Cyclophane 24 is so strained that it exceeds the corresponding Dewar benzene precursor in energy and thermally reverts to the latter with a half-life of 15 +/- 5 min at -20 degrees C (DeltaG++ = 18.3 +/- 0.3 kcal mol(-1)).
Journal Article↗
Preliminary results of a monitoring system to confirm the preservation of cavernous nerves.
BACKGROUND: It is important to preserve the neurovascular bundle (NVB) during nerve-sparing surgery. This article presents the preliminary results of our monitoring system for the postoperative preservation of erectile function. METHODS: In 15 patients undergoing radical prostatectomy and 20 patients undergoing radical cystoprostatectomy, intraoperative electrical stimulation along the NVB was performed to measure changes in intracavernous pressure before and after prostate removal. Seven of the radical prostatectomy patients and eight of the radical cystoprostatectomy patients underwent nerve-sparing surgery. Postoperative erectile function was evaluated in 25 patients not receiving adjuvant hormonal therapy. RESULTS: The NVB was judged to be preserved at least on one side electrophysiologically in 14 of 15 patients. Pathologically, three patients had pT3 cancer. Postoperatively, sufficient erectile function was demonstrated using the International Index of Erectile Function 5 in three patients, nocturnal penile tumescence in three patients, and a questionnaire or an interview in three patients. The other patients were incompletely erectile. None of the 11 patients not receiving adjuvant hormonal therapy, in whom NVB was not preserved, were erectile. CONCLUSION: If the successful criterion of nerve-sparing surgery is defined as a change in intracavernous pressure of 4 cm H2O or more being observed at least unilaterally, and the successful criteria of erectile function preservation includes being sufficiently erectile as revealed by an interview, the sensitivity of our system was 69.2% (9/13) and the specificity was 100% (12/12). Neither adverse reactions to the measurement, nor inadequacy of cancer excision accompanying NVB sparing, were observed. These results suggest that our system can predict postoperative erectile function fairly accurately.
Aged↗
Coaggregation among nonflocculating bacteria isolated from activated sludge.
Thirty-two strains of nonflocculating bacteria isolated from sewage-activated sludge were tested by a spectrophotometric assay for their ability to coaggregate with one other in two-membered systems. Among these strains, eight showed significant (74 to 99%) coaggregation with Acinetobacter johnsonii S35 while only four strains coaggregated, to a lesser extent (43 to 65%), with Acinetobacter junii S33. The extent and pattern of coaggregation as well as the aggregate size showed good correlation with cellular characteristics of the coaggregating partners. These strains were identified by sequencing of full-length 16S rRNA genes. A. johnsonii S35 could coaggregate with strains of several genera, such as Oligotropha carboxidovorans, Microbacterium esteraromaticum, and Xanthomonas spp. The role of Acinetobacter isolates as bridging organisms in multigeneric coaggregates is indicated. This investigation revealed the role of much-neglected nonflocculating bacteria in floc formation in activated sludge.
Acinetobacter↗
Supramolecular graphyne: a C(sp)-H...N hydrogen-bonded unique network structure of 2,4,6-triethynyl-1,3,5-triazine.
The crystallization of 2,4,6-triethynyl-1,3,5-triazine (2) leads to a pi-stacked layered structure of a C(sp)-H...N hydrogen-bonded unique hexagonal network structure, which may be regarded as a supramolecular analogue of a hitherto unknown graphyne network: in-plane intermolecular interactions are short and linear H...N contacts (2.31 and 2.34 A) and the interlayer separation is 3.23 A.
Journal Article↗
Autopsy findings of patients with urological neoplasms.
BACKGROUND: A study was carried out to gain extensive understanding of the disease status in patients who had suffered and died of urological neoplasms. METHODS: The subjects were 524 patients who had died at the Department of Urology of Gunma Cancer Center. The autopsy rate for each urological, neoplasm, the extent of the disease, and incidental diseases were analyzed. RESULTS: Autopsies were performed in 27.1% (142/524) of the patients. Frequent metastatic sites were the lymph nodes, bone, and lung in prostate neoplasms; the lymph nodes, liver, and lung in bladder neoplasms; and the lymph nodes, lung, and bone in kidney neoplasms. In the 116 patients with these three major urological neoplasms, the autopsy findings of all patients were compatible with progression of the disease, except for 5 cases (acute myocardial infarction in 2 and liver failure in 3). Multiple primary cancers were seen in 21.6% (25/116), and other cancers that caused death, apart from those at urological sites, were confirmed in 7 patients (pancreas in 2, and esophagus, lung, gallbladder, liver, and uterus in 1 patient each). CONCLUSION: Autopsies revealed the macroscopic and microscopic extent of the disease and the presence of incidental disease beyond the diagnosis made in the patient's lifetime.
Adolescent↗
Tumor-associated tissue eosinophilia of penile cancer.
BACKGROUND: Tumor-associated tissue eosinophilia (TATE) occurs in many kinds of cancer. This study analyzed whether TATE improves the survival of penile cancer patients. METHODS: In 17 patients with penile cancer, survival was compared between the TATE-positive group and the TATE-negative group. Tissue eosinophils were observed by transmission electron microscopy. RESULTS: In all cases, 5-year survival was 72.9% in the TATE-positive group (n = 8) and 38.9% in the TATE-negative group (n = 9; P = 0.131). In stage III and IV, it was 60% in the TATE-positive group (n = 5) and 0% in the TATE-negative group (n = 5; P = 0.058). Transmission electron microscopy images revealed the vigorous infiltration of tissue eosinophils. CONCLUSIONS: It is suggested that TATE improves the survival of patients with advanced penile cancer. However, a greater number of subjects is needed to prove statistical significance.
Eosinophilia↗