s-Indacene Revisited: Modular Synthesis and Modulation of Structures and Molecular Orbitals of Hexaaryl Derivatives.

Though s-indacene is an intriguing antiaromatic hydrocarbon of 12 π-electrons, it has been underrepresented due to the lack of efficient and versatile methods to prepare stable derivatives. Herein we report a concise and modular synthetic method for hexaaryl-s-indacene derivatives bearing electron-donating/-accepting groups at specific positions to furnish C2h-, D2h-, and C2v-symmetric substitution patterns. We also report the effects of substituents on their molecular structures, frontier molecular orbital (MO) levels, and magnetically induced ring current tropicities. Both theoretical calculations and X-ray structure analyses indicate that the derivatives of the C2h-substitution pattern adopt different C2h structures with significant bond length alternation depending on the electronic property of the substituents. Due to the nonuniform distribution of the frontier MOs, their energy levels are selectively modulated by the electron-donating substituents. This leads to the inversion of the HOMO and HOMO-1 sequences with respect to those of the intrinsic s-indacene as theoretically predicted and experimentally proven by the absorption spectra at visible and near-infrared regions. The NICS values and the 1H NMR chemical shifts of the s-indacene derivatives indicate their weak antiaromaticity. The different tropicities are explained by the modulation of the HOMO and HOMO-1 levels. In addition, for the hexaxylyl derivative, weak fluorescence from the S2 excited state was detected due to the large energy gap between the S1 and S2 states. Notably, an organic field-effect transistor (OFET) fabricated using the hexaxylyl derivative exhibited moderate hole carrier mobility, a result which opens the door for optoelectronic applications of s-indacene derivatives.

Dianion and Dication of Tetracyclopentatetraphenylene as Decoupled Annulene-within-an-Annulene Models.

The dianion and dication of tetramesityl-substituted tetracyclopentatetraphenylene, a circulene consisting of alternating five- and six-membered rings, have been generated by reduction with alkali metals and oxidation with antimony(V) halides, respectively. They are theoretically predicted to adopt double annulenoid structures called annulene-within-an-annulene models in which the outer and inner conjugation circuits are significantly decoupled. The theoretical structures were experimentally proven by X-ray crystallographic analyses and the electronic configurations were supported by MCD spectra. Based on the 13 C NMR chemical shifts, negative and positive charges are shown to be located mainly at the outer periphery, indicating that the dianion and dication have delocalized 22-π and 18-π electron outer perimeters, respectively, and 8-π electron structure at the inner ring. Notably, the dianion has an open-shell character, whereas the dication has a closed-shell ground state.

9,10-Dihydro- as-indacenodithiophenes: Isomers with an as-Indacene Core.

Two isomers of 9,10-dihydro- as-indacenodithiophenes (DIDTs) and the corresponding diketones having an as-indacene core were synthesized. Their thermal, photophysical, and electrochemical properties were investigated, revealing that they depend on the direction of the fusion of the thiophene rings. For the DIDTs, the effect of the mode of ring fusion on the physical properties is discussed by comparison with the previously reported derivatives of DIDT isomers with an s-indacene core. The observed difference between the highest occupied molecular orbital (HOMO)/lowest unoccupied molecular orbital (LUMO) levels of the DIDT isomers is ascribed to the efficiency of π-conjugation, which depends on α- or ß-linkage between the terminal thiophenes with the central benzene ring. In addition, the effect of the peripheral aromatic ring (thiophene or benzene) is elucidated by comparison with indeno[2,1- a]fluorene (DIF) bearing an as-indacene core. The HOMO levels of DIDTs are significantly raised compared to that of structurally related DIF because of electron-donating character of the thiophene rings. For the DIDT diketones, structural effect due to the proximate carbonyl groups is discussed by comparison with the isomers with remote carbonyl groups. In diketones bearing proximate carbonyl groups, the LUMO levels are destabilized owing to antibonding interaction between the carbonyl oxygen atoms, resulting in approach of the LUMO and LUMO+1 energy levels.

Fluoreno[2,3-b]fluorene vs Indeno[2,1-b]fluorene: Unusual Relationship between the Number of π Electrons and Excitation Energy in m-Quinodimethane-Type Singlet Diradicaloids.

The dimesityl derivative of fluoreno[2,3-b]fluorene (6b) was synthesized and its structure and physical properties were investigated to elucidate the effects of its enhanced open-shell character, which was predicted theoretically in comparison with the smaller congener indeno[2,1-b]fluorene (5b). All structural and physical properties are in accordance with the theoretical predictions and can be interpreted in terms of the resonance contributors. The most remarkable spectroscopic property is the larger excitation energy of 24π-electron hydrocarbon 6b than that of 20π-electron system 5b in their lowest energy absorption bands of electronic spectra, a trend that is contrary to the well-known feature for common, alternant aromatic hydrocarbons. The theoretical basis of this unusual behavior was elucidated on the basis of the balance between the diradical character, exchange integral, and HOMO-LUMO gap and was confirmed by a complete-active-space configuration-interaction method with two electrons in two orbitals for the corresponding parent hydrocarbons 5a and 6a.

Non-alternant non-benzenoid kekulenes: the birth of a new kekulene family.

"Kekulene" is a doughnut-like shaped polycyclic aromatic hydrocarbon consisting of cyclically arrayed benzene rings. It has attracted a great deal of theoretical interest because it is regarded as an ideal model to study conjugation circuits of π electrons, i.e. whether they delocalize locally in benzene rings or globally throughout the molecule. Though kekulene was synthesized in 1978, it was the only known compound of this class of compounds for a long time. Recently, new kekulene-related molecules, septulene, which is a non-alternant benzenoid hydrocarbon, and a tetracyclopentatetraphenylene (TCPTP) derivative belonging to non-alternant non-benzenoid hydrocarbons, were synthesized. This article presents theoretical and experimental aspects of kekulene-related molecules focusing on the viewpoint of conjugation circuits by classifying them into three types: benzenoid kekulenes including kekulene itself and septulene, yet unknown anti-kekulene and non-alternant non-benzenoid kekulenes represented by TCPTP.

Association of left atrial reservoir function with left atrial structural remodeling related to left ventricular dysfunction in asymptomatic patients with hypertension: evaluation by two-dimensional speckle-tracking echocardiography.

Left atrial (LA) structural and functional abnormalities are vital steps on the pathway toward heart failure with preserved ejection fraction in asymptomatic patients. The purpose of this study was to assess the relationship of LA function, particularly reservoir function, with LA structural remodeling related to the left ventricular (LV) dysfunction in asymptomatic patients with hypertension (HT) using conventional, tissue Doppler, and 2-D speckle-tracking echocardiography. Fifty age-matched healthy individuals and 140 patients with HT, including 75 with LA volume index (LAVI)<29 ml/m2 (normal LA group) and 65 with LAVI≥29 ml/m2 (large LA group), were enrolled. We defined peak early diastolic transmitral flow velocity/peak early diastolic mitral annular motion velocity (E/e')/peak systolic LA strain (S-LAs) as LA diastolic stiffness. The LV mass index, relative LV wall thickness, peak atrial systolic transmitral flow velocity, LA total, active, and passive emptying volume indexes, and E/e'/S-LAs were greatest, and S-LAs, peak early diastolic LA strain, peak systolic LV longitudinal strain and circumferential strain rate, and peak early diastolic LV radial strain rate were lower in the large LA group compared with control and/or normal LA group. Multivariate linear regression analysis revealed that aging, LA remodeling, and LV systolic and diastolic dysfunction are defined as strong predictors related to increased LA diastolic stiffness in the large LA group. HT alters LA dynamics significantly, with resultant increased LA volume and diastolic stiffness related to LV diastolic and systolic dysfunction, even in asymptomatic patients. Earlier treatment with renin–angiotensin system inhibitors may improve abnormal LA-LV interaction in this patient population.

Tetracyclopenta[def,jkl,pqr,vwx]tetraphenylene: a potential tetraradicaloid hydrocarbon.

A tetramesityl derivative of hitherto unknown tetracyclopenta[def,jkl,pqr,vwx]tetraphenylene (TCPTP), which is a potential tetraradicaloid hydrocarbon, was synthesized. Theoretical calculations based on spin-flip time-dependent density functional theory predict that the closed-shell D2h form of TCPTP is more stable than the open-shell D4h form with its slightly tetraradical character. The tetramesityl derivative (Mes)4 -TCPTP exhibits remarkable antiaromaticity as a result of the peripheral 20-π-electron circuit, which causes an absorption maximum at a long wavelength and a small HOMO-LUMO gap. In solution, (Mes)4 -TCPTP most likely adopts rapidly equilibrating D2h structures that interconvert via the D4h transition state. X-ray crystallographic analysis showed (Mes)4 -TCPTP as an approximate D2h structure.

Influence of comorbid cardiovascular risk factors on left atrial-left ventricular interaction in asymptomatic patients: clinical application of two-dimensional speckle-tracking echocardiography.

Previous studies have examined the negative impacts of individual cardiovascular risk (CVR) factors on left atrial (LA)-left ventricular (LV) interaction, whereas the combined effects of these risk factors are insufficiently elucidated. We studied 176 asymptomatic patients with CVR factors and age-matched 50 healthy individuals by conventional and 2-dimensional speckle-tracking echocardiography. The patients were classified into 2 groups according to the number of CVR factors: one risk factor (single) group (n = 79) and 2 or more risk factors (comorbid) group (n = 97). The peak early diastolic transmitral flow velocity (E)/peak early diastolic mitral annular motion velocity (e')/peak systolic LA strain (S-LAs) was used as a surrogate for LA stiffness during ventricular systole. The E/e'/S-LAs was greatest in the comorbid group. The peak systolic LV circumferential and radial strains, peak early diastolic LV radial strain rate, and peak early diastolic LA strain and strain rate were lower in the comorbid group than in the single group. Multivariate regression analysis identified age, body mass index, systolic blood pressure, end-systolic LV diameter, peak systolic mitral annular motion velocity (s'), and peak systolic LV radial strain in the comorbid group, and peak atrial systolic transmitral fl ow velocity and s' in the single group, as independent predictors of E/e'/S-LAs. Subtle LA and LV dysfunction with individual CVR factors were more aggravated with the comorbid conditions in asymptomatic patients.

Preparation of paper scintillators and their effective use in radiation testing for α- and ß- particles in radioactive liquid, solid, and gas contaminants.

A paper scintillator, which is composed of an organic scintillator encapsulated in silica nanoparticles adsorbed on three types of micrometer-size silica fine powder (scintillator-silica FP), was prepared by a paper making method. The scintillator-silica FP was found to be distributed throughout the paper scintillator, as shown in its emission images. Surface photoluminescence spectra depended on the amount of scintillator-silica FP and were assigned to the radioluminescence excited upon irradiation with ß-particles of 45Ca. The onset channels of the pulse height spectra of 3H, 63Ni, 14C, 45Ca, 204Tl, and 32P indicated their dependence on linear energy from 18.6 to 1711 keV using the H mode in LSC-7400 for the paper scintillator to detect their maximum ß-particles energies. The paper scintillator could also detect α-particles from 211At, and its pulse height spectrum was wider than that of a liquid scintillator (LS). Radon gas in air was collected using a gas sampler with the paper scintillator, and radiation from daughter nuclides was detected for 10 days. The adsorption/absorption of tritiated water onto/into the paper scintillator after dipping, dropping, and immersing the paper scintillator into tritiated water led to the detection of ß-particles under different conditions of tritiated water for determining whether the radioactivity in the solution, is high or low. The paper scintillator smeared with tritiated contaminants detected tritium without requiring an LS, which is used in a smear paper.

Paper Scintillator Incorporated with Scintillator-Silica Fine Powders: Photophysical Characterization and Proof of Concept Demonstration of Tritium Detection.

In order to decrease the generation of radioactive waste, it is of interest to develop a scintillator capable of absorbing tritiated solutions for efficient detection of low-energy ß-particles from tritium. In this work, paper scintillator incorporated with scintillator-silica fine powders (FPs), which is composed of scintillator-silica nanoparticles (NPs) attached to silica FP, was fabricated and evaluated. The scintillator-silica NPs contained liquid scintillators benzoic acid, 2,5-diphenyloxazole (PPO), and 1,4-bis(5-phenyloxazol-2-yl) benzene (POPOP). Photophysical characterization was executed by means of photoluminescence, fluorescence lifetime, quantum efficiency, and radioluminescence under X-ray excitation. POPOP emission was confirmed by absorbing the emissions from benzoic acid and PPO. Radioluminescence results confirmed POPOP emission. Fluorescence lifetime analysis yielded a 1.29 ± 0.01 ns main fast decay (64.2%) combined with a 4.00 ± 0.04 ns slower decay (35.8%). The combined luminescence results suggested that most POPOP in the paper scintillator was solvated. At 301 nm, the average quantum efficiency from both faces of the paper scintillator was about 4%, and at 370 nm, it was about 11%. The paper scintillator detected 3H ß-particles by dipping the paper scintillator into tritiated water without a liquid scintillator. The counting efficiency depended on water content in the paper scintillator, and it increased to above 10% for tritium activity less than 200 dpm since it was preferentially adsorbed by vapor pressure isotopic effect and isotopic exchanged tritium on the surface of the scintillator-silica FP in the paper scintillator.

Negative impact of cardiovascular risk factors on left atrial and left ventricular function related to aortic stiffness--new application of 2-dimensional speckle-tracking echocardiography.

BACKGROUND: The aim of the present study was to detect earlier the negative effect of cardiovascular risk (CVR) factors on left atrial (LA) and left ventricular (LV) function related to abdominal aortic (AAO) stiffness using 2-dimensional speckle-tracking echocardiography (2DSTE) in asymptomatic patients. METHODS AND RESULTS: One hundred and twelve patients with CVR factors and 56 healthy individuals were studied. 2DSTE data were acquired for determination of LA and LV myocardial and AAO wall deformations. LA volume index, LV mass index, ratio of early diastolic transmitral flow to mitral annular velocity (E/e')/peak systolic LA strain (S-LAs), and AAO stiffness were greater, and peak early diastolic LV longitudinal strain rate (SR-LVe) was lower in the patient group. Among the significantly correlated variables with AAO stiffness on univariate analysis, multivariate linear regression analysis identified SR-LVe and (E/e')/S-LAs in the patient group, and only age in the healthy group, as independent predictor of AAO stiffness. CONCLUSIONS: Structural and functional changes in the LA and LV and AAO stiffening were accelerated with CVR factors, and higher AAO stiffness was associated with deteriorated LA compliance and impaired LV relaxation in asymptomatic patients with CVR factors. 2DSTE has a potential for earlier detection of abnormal LA and LV function related to increased AAO stiffness.

Vascular aging of common carotid artery and abdominal aorta in clinically normal individuals and preclinical patients with cardiovascular risk factors: diagnostic value of two-dimensional speckle-tracking echocardiography.

Increased arterial stiffness is becoming an increasing health care problem as the population ages. Our aim was to detect the vascular aging of common carotid artery (CCA) and abdominal aorta (AAO) more easily and earlier using two-dimensional speckle-tracking echocardiography, and to evaluate the regional differences in mechanical properties related to changes in aging between the two arteries in preclinical patients. Twenty-nine clinically normal individuals and 68 preclinical patients with cardiovascular risk factors were examined. The peak circumferential strains were measured from the short-axis views of the CCA and AAO, and each stiffness ß was determined. The CCA and AAO diameters increased with advanced age, and the latter diameter was widely distributed in patients of 50 years or older. The mean strain and stiffness index of the AAO were greater and lower, respectively, than those of the CCA at all ages. The CCA and AAO strains decreased with age, expressing dramatic declines before the fifth decade of life. The CCA and AAO stiffness indices increased with age, expressing rapid ascents after the fifth decade of life, particularly in the AAO. The best markers of subclinical arterial aging were strain in younger persons and stiffness in older individuals. Two-dimensional speckle-tracking echocardiography is a new tool that can be used to directly and easily evaluate arterial function.

Effect of an increase in left ventricular pressure overload on left atrial-left ventricular coupling in patients with hypertension: a two-dimensional speckle tracking echocardiographic study.

BACKGROUND: Two-dimensional speckle tracking echocardiography (2DSTE) has recently been applied to evaluate left atrial (LA) function in addition to left ventricular (LV) function. However, whether 2DSTE can provide insight into LA-LV interaction related to an increase in LV pressure overload remains unknown. METHODS: One hundred five asymptomatic patients with hypertension were studied by conventional, pulsed and tissue Doppler, and 2DSTE. Hypertensive patients were classified into 2 groups according to the ratio of early diastolic to atrial systolic velocity (E/A) of transmitral flow: E/A ≥ 1 (n = 37) and E/A < 1 (n = 68). We used (E/peak early diastolic mitral annular motion velocity [e'])/peak systolic LA strain (S-LAs) and E/e', as parameters of LA stiffness during ventricular systole and LV diastolic stiffness, respectively. RESULTS: The peak early diastolic LV longitudinal strain rate, and peak early diastolic LA strain and strain rate were lower in the E/A < 1 group than in the E/A ≥ 1 group. The E/e'/S-LAs and E/e' were greater in the E/A < 1 group. In the E/A < 1 group, systolic blood pressure (SBP) correlated with LV wall thickness parameters, A, e', E/e', peak early diastolic LV longitudinal strain rate, and E/e'/S-LAs. Multivariate regression analysis indicated that A, E/e', and E/e'/S-LAs were defined as strong predictors related to SBP. CONCLUSION: In patients with hypertension, an elevation in SBP leads to increased LA stiffness during ventricular systole and LV diastolic stiffness, in association with continued and further advanced LV diastolic dysfunction. 2DSTE is considered a sensitive tool for detecting abnormal LA-LV coupling related to an increased LV pressure overload.

[Proposal of a cloud chamber experiment using diagnostic X-ray apparatus and an analysis assisted by a simulation code].

A cloud chamber is a radiation detector that can visualize the tracks of charged particles. In this study, we developed a middle-type cloud chamber for use in practical training using a diagnostic X-ray apparatus. Because our cloud chamber has a heater to vaporize ethanol and features antifogging glass, it is possible to observe the vapor trails for a long time without the need for fine adjustments. X-rays with a tube voltage of 40 kV or of 120 kV (with a 21-mm aluminum filter) were irradiated at the chamber and the various phenomena were observed. We explain these phenomena in terms of the range of electrons and/or interactions between X-rays and matter and conclude that our analysis is consistent with analysis using the Monte Carlo simulation code EGS5.

Selective detection of fast and thermal neutrons in mixed-radiation fields using tungsten-silica and gold-iodine-silica nanoparticles and their boron-loaded aqueous dispersions.

Tungsten-silica and gold-iodine-silica nanoparticles and their boron-loaded aqueous dispersions were used to selectively detect fast and thermal neutrons in mixed-radiation fields generated by a cyclotron on the order of mSv at a neutron flux of 1.0 ×106(neutron/sec∙cm2). The photo-image intensity, fluorescence spectra, absorption spectra, and XRD of their aqueous dispersions were measured immediately and eighteen days after irradiation. The immediate measurements of photo-image intensity and fluorescence spectral area ratios for gold-iodine-silica nanoparticle aqueous dispersions indicated the dose dependence of photo-image intensity and fluorescence spectral area ratios. Measurements of the relative fluorescence and absorption spectral areas of gold-iodine-silica nanoparticle aqueous dispersions 18 days after irradiation also showed similar dose dependences. The precipitates of gold-iodine-silica nanoparticles showed a linear relationship between the XRD peak ratio and the dose with a correlation coefficient of 0.9. The photo-image intensities, fluorescence spectral area, absorption spectral area, and XRD peak ratios were found to be affected by fast and thermal neutrons. Simple methods of fluorescence, absorption, and XRD measurements are proposed for the selective detection of fast and thermal neutrons in mixed-radiation fields.

Early Prediction of Radiotherapeutic Efficacy in a Mouse Model of Non-Small Cell Lung Carcinoma Using 18F-FLT and 18F-FDG PET/CT.

This study investigated the usefulness of [18F]-3'-deoxy-3'-fluorothymidine (18F-FLT) and [18F]-fluoro-2-deoxy-D-glucose (18F-FDG) positron emission tomography (PET)/computed tomography (CT) imaging for predicting the therapeutic efficacy of non-small cell lung cancer (NSCLC) irradiation at an early stage after radiation treatment. Mice were xenografted with the human lung adenocarcinoma line A549 or large cell lung cancer line FT821. Tumour uptake of 18F-FLT and 18F-FDG was imaged using PET/CT before and 1 week after irradiation. In A549 tumours, 18F-FLT uptake was significantly decreased, and 18F-FDG uptake was unchanged post-irradiation compared with pre-irradiation. In FT821 tumours, uptake of both 18F-FLT and 18F-FDG uptake was substantially decreased post-irradiation compared with pre-irradiation. In both xenografts, tumour volumes in the irradiated groups were significantly decreased compared with those in the control group. 18F-FLT is expected to contribute to individual NSCLC therapy because it accurately evaluates the decrease in tumour activity that cannot be captured by 18F-FDG. 18F-FDG may be useful for evaluating surviving cells without being affected by the inflammatory reaction at an extremely early stage, approximately 1 week after irradiation. Combined use of 18F-FLT and 18F-FDG PET/CT imaging may increase the accurate prediction of radiotherapy efficacy, which may lead to improved patient outcomes and minimally invasive personalised therapy. J. Med. Invest. 70 : 361-368, August, 2023.

Properties of signal intensities observed with individual probes of GeneChip Rat Gene 1.0 ST Array, an affymetric microarray system.

For proper evaluation of the results of microarray experiments, it is important to understand how the signal intensities of individual probes are determined. Our previous studies revealed that signal intensities of individual probes in the Agilent array system (code G4131F) are largely dependent upon the location of the probes in the mRNA. In the present study, we examined the properties of signal intensities of individual probes in an Affymetrix array system (GeneChip Rat Gene 1.0 ST Array), in which a random primer fused to the T7 promoter sequence is employed. Distinct from the Agilent array system, individual probes used in this Affymetrix array system did not show the probe-location effects, but gave relatively diverse signal intensities. However, the diversities of the signal intensities of these individual probes were not due to experimental error.

Early detection of abnormal left atrial-left ventricular-arterial coupling in preclinical patients with cardiovascular risk factors: evaluation by two-dimensional speckle-tracking echocardiography.

AIMS: Data are lacking on the left atrial (LA)-left ventricular (LV)-arterial coupling for evaluating the functional abnormalities in the left heart disease, whereas LA-LV or LV-arterial coupling has been recognized. This study was designed to earlier detect the abnormal LA-LV-arterial coupling using two-dimensional speckle-tracking echocardiography (2DSTE) in patients with cardiovascular risk factors and no overt cardiovascular disease. METHODS AND RESULTS: We studied 30 age-matched healthy individuals and 64 preclinical patients with cardiovascular risk factors, who measured carotid arterial intima-media thickness and stiffness ß by M-mode ultrasonography, and strain and strain rate of the LA and LV walls by 2DSTE. The stiffness ß and LA volume index (LAVI) were greater in the patient group than in the control group. However, the peak systolic LV longitudinal strain, peak systolic and early diastolic LV longitudinal strain rates, peak systolic and early diastolic LA strains and strain rates, and peak atrial systolic LA strain rate were lower in the patient group. There were correlations between the stiffness ß and the age, pulse pressure, LAVI, peak early diastolic LV longitudinal strain rate, and all LA strains and strain rate variables. Multivariate regression analysis indicated that peak early diastolic LV longitudinal strain rate and peak LA strain rate during ventricular systole are defined as strong predictors related to stiffness ß. CONCLUSION: Impaired LA and LV relaxation in the longitudinal direction are early signs of abnormal LA-LV coupling related to arterial stiffness in preclinical patients with cardiovascular risk factors. 2DSTE enables the quantitative assessment of the LA and LV function, and can be considered a sensitive tool for detecting the abnormal LA-LV-arterial coupling.

Effect of different examination conditions on image quality and quantitative value of amyloid positron emission tomography using 18F-flutemetamol.

OBJECTIVE: The recommended start time for 18F-flutemetamol amyloid positron emission tomography (PET) examination is 60-120 min after 18F-flutemetamol injection, while an acquisition time of 10-30 min is generally recommended. We aimed to elucidate the effects of different examination conditions on image quality, diagnostic ability, and quantitative value of amyloid PET using 18F-flutemetamol. METHODS: We acquired data on a Discovery PET/computed tomography 710 scanner using Hoffman brain and pillar phantoms with 20 MBq of 18F for 30 min. The images were reconstructed into 10-, 20-, and 30-min periods. The ordered subset-expectation maximization algorithm was used for image reconstruction, which uses a 2- or 4-mm Gaussian filter and a combination of iteration and subset numbers. The percentage contrast and coefficient of variation (CV; as the image noise) were used as physical evaluation indices for reconstructed images, and images with superior contrast and low image noise were selected for clinical evaluation. The imaging data of 15 symptomatic patients (n = 7 and n = 8 for positive and negative diagnoses of Alzheimer's disease, respectively) were reconstructed under the phantom study conditions. Radiographers visually evaluated and ranked the clinical images based on the overall contrast and image noise, and nuclear medicine specialists diagnosed Alzheimer's disease. We compared the standardized uptake value ratio (SUVR) obtained with different acquisition conditions. RESULTS: The basic study using the phantom revealed high convergence of contrast and image noise in five patterns of acquisition time and filter strengths. Regarding visual evaluation, the use of a 2-mm Gaussian filter caused difficulties in diagnosis because the brain parenchymal accumulation was mottled with high image noise. Differences in image quality and diagnostic ability due to different examination times were not significant. Differences in the SUVR were not significant in patients with a negative Alzheimer's disease diagnosis; in patients with a positive diagnosis, the SUVR showed significant fluctuation depending on the acquisition conditions. CONCLUSION: The differences in image quality and diagnostic performance due to the differences in 10-min acquisition time were not significant; however, of note, SUVR showed significant fluctuation depending on the acquisition conditions in patients diagnosed with Alzheimer's disease.

Possible mechanisms of left ventricular torsion evaluated by cardioreparative effects of telmisartan in patients with hypertension.

AIMS: Left ventricular (LV) torsion may be an important component of normal LV systolic function. However, its mechanics remain unresolved. Two-dimensional (2-D) strain imaging is increasingly used to quantify LV torsion in the clinical setting. Telmisartan has cardioreparative effects, including attenuation of subendocardial myocardial fibrosis and improvement of LV remodelling. To clarify the mechanisms of LV torsion, in the present study, we evaluated changes in LV longitudinal deformation and torsion after medication with telmisartan using 2-D strain imaging in patients with hypertension (HT). METHODS AND RESULTS: Telmisartan (20-40 mg daily) was administered to 37 previously untreated patients with HT. Two-dimensional strain echocardiography was performed after medication had been continued for 1-2 months with normal values for blood pressure (BP) (phase I) and for 12 months (phase II). In the phase II, relative LV wall thickness, LV mass index, LV torsion, and torsional rate were reduced, whereas the mean peak systolic longitudinal strain and strain rate were increased, compared to the phase I. LV torsion correlated well with relative LV wall thickness, but not LV mass index. CONCLUSION: Our results obtained from cardioreparative effects of telmisartan suggested that LV torsion is associated with systolic longitudinal deformation related to subendocardial myocardial fibrosis, and/or LV concentric hypertrophy-related difference in torques between the subendocardial and subepicardial sides.