Two-Photon Absorption Properties of Self-Assemblies of Butadiyne-Linked Bis(Imidazolylporphyrin)

Supramolecular porphyrin self-assemblies have been prepared from butadiyne-linked bis(imidazolylporphyrin) by complementary coordination of imidazole to zinc, and their two-photon absorption (2PA) and higher-order nonlinear absorption properties were investigated over femtosecond time scales using an open-aperture Z-scan method. The self-assembled porphyrin dimer of the conjugated monozinc bisporphyrin 7D was shown to have a large 2PA cross section (7.6 x 10(3) GM, where 1 GM = 10(-50) cm(4) s molecule(-1) photon(-1)) at 887 nm. By comparison of this result with that for a meso-meso-linked porphyrin array without the butadiyne connection (3.7 x 10(2) GM at 964 nm), it was demonstrated that the predominant factor in this significant enhancement of the cross section was the expansion of porphyrin-porphyrin pi-conjugation. Self-coordination and monozinc metalation were also found to be contributing factors. Furthermore, a novel self-assembled porphyrin polymer 8P consisting of a biszinc complex with a mean molecular weight of M(n) = 1.5 x 10(5) Da was shown to exhibit an extraordinarily large two-photon absorption cross section (4.4 x 10(5) GM at 873 nm). Nanosecond Z-scan experiments for 7D and 8P were also undertaken and resulted in the measurement of large effective 2PA cross sections, including the excited-state absorption (2.1 x 10(5) GM for 7D and 2.2 x 10(7) GM for 8P, respectively). Finally, three-photon absorption was observed by femtosecond Z-scan experiments at 1188 nm (7.1 x 10(-89) m(6) s(2)) and 1282 nm (1.8 x 10(-89) m(6) s(2)), an observation which is the first of its kind in porphyrin chemistry.

Abrasion resistance of titanium nitride coatings formed on titanium by ion-beam-assisted deposition

To improve the physical properties of the pure titanium surface, thin titanium nitride (TiN) films were deposited by means of ion-beam-assisted deposition. Film structure was confirmed as TiN by X-ray diffraction analysis. Surface hardness and abrasion resistance were significantly improved on TiN-coated specimens. Five combinations of oral hygiene instruments and materials were applied to the specimens as simulations of the oral environment. Treatment with the metal scaler and ultrasonic scaler severely changed the surface features and significantly increased the surface roughness parameters on pure titanium controls, whereas only small scratches and dull undulations were seen on the TiN-coated specimens. Profilometric tracings and scanning electron micrographs demonstrated the improved abrasion resistance of the TiN-coated specimens.

Second Hyperpolarizability (γ) of Singlet Diradical System: Dependence of γ on the Diradical Character

The dependence of the second hyperpolarizability (gamma) on the diradical character (y) for singlet diradical systems is investigated using a model compound, the p-quinodimethane (PQM) molecule with different both-end carbon-carbon (C-C) bond lengths, by several ab initio molecular orbital and density functional theory methods. The diradical character based on UHF calculations indicates that at equilibrium geometry PQM is in a singlet ground state and primarily exhibits a quinoid structure, whereas the diradical character increases when increasing both-end C-C bond lengths. At the highest level of approximation, that is, using the UCCSD(T) method with the 6-31G+diffuse p (zeta = 0.0523) basis set, the longitudinal static gamma of PQM presents a maximum value for intermediate diradical character (y approximately 0.5) while the gamma values are larger for intermediate and large diradical character (y approximately 0.5-0.7) than for small diradical character (y < 0.2). This feature suggests that the gamma values of singlet diradical systems in the intermediate and somewhat strong correlation regimes are significantly enhanced as compared to those in the weak correlation regime. These results are substantiated by a complementary study of the variation in gamma upon twisted ethylene.

New chromophores from click chemistry for two-photon absorption and tuneable photoluminescence

New multipolar derivatives built from triazole moieties that combine full transparency and strong TPA in the visible region as well as fully tuneable fluorescence have been designed; such chromophores open a new route for optical limiting.

Bonding between resin luting cement and glass infiltrated alumina-reinforced ceramics with silane coupling agent

The purpose of this study was to evaluate the shear bond strengths of three dual-cured resin luting cements (Linkmax HV, Panavia Fluoro Cement, and RelyX ARC) to glass-infiltrated alumina-reinforced ceramic material and the effect of four silane coupling agents (Clearfil Porcelain Bond, GC Ceramic Primer, Porcelain LinerM, and Tokuso Ceramic Primer) on the bond strength. The two type-shaped of In-Ceram alumina ceramic glass-infiltrated specimens were untreated or treated with one of the four ceramic primers and then cemented together with one of the three dual-cured resin luting cements. Half of the specimens were stored in water at 37 degrees C for 24 h and the other half thermocycled 20,000 times before shear bond strength testing. Surface treatment by all silane coupling agents improved the shear bond strength compared with non-treatment. The specimens treated with Clearfil Porcelain Bond showed significantly greater shear bond strength than any of the other three silane coupling agents regardless of resin luting cements and thermocycling except for the use of Panavia Fluoro Cement at 20,000 thermocycles. When the alumina-reinforced ceramic material was treated with any silane coupling agent except GC Ceramic Primer and cemented with Linkmax HV, no significant differences in bond strength were noted between after water storage and after 20,000 thermocycles. After 20,000 thermocycles, all specimens except for the combined use of Clearfil Porcelain Bond or GC Ceramic Primer and Linkmax HV and GC Ceramic Primer and Panavia Fluoro Cement showed adhesive failures at the ceramic-resin luting cement interface.

Ictal magnetoencephalographic study in a patient with ring 20 syndrome

OBJECTIVE

To report the ictal magnetoencephalography (MEG) in a patient with ring chromosome 20 mosaicism, a rare chromosomal anomaly associated with intractable epilepsy.

METHODS

MEG and simultaneous EEG were recorded with a 204 channel whole head MEG system. Ten habitual seizures occurred during the acquisition, which was done twice. The equivalent current dipoles (ECDs) for ictal discharges on MEG were calculated using a single dipole model. The ECDs were superimposed on a magnetic resonance image.

RESULTS

During the seizures, EEG showed prolonged bursts of 5-6 Hz high voltage slow waves with spike components, dominantly in the bilateral frontal region. MEG showed epileptiform discharges corresponding to the ictal EEG. Ictal discharges on MEG were dominant in the frontal area in the initial portion, and then spread in the bilateral temporal area in the middle of the seizure. ECDs obtained from the spikes of the initial portion were clustered in the medial frontal lobe.

CONCLUSIONS

The source of the ictal MEG was localised in the medial frontal lobe. The findings suggest that the mechanism underlying epilepsy in this case might be similar to medial frontal lobe epilepsy. Ictal MEG is a valuable tool for detecting the site of seizure onset.

Strong two-photon absorption of self-assembled butadiyne-linked bisporphyrin

Two-photon absorption (2PA) properties of self-assembled porphyrins were investigated. The butadiyne-linked porphyrin array exhibited a 20 times larger 2PA cross section than the meso-meso-linked self-assembled array due to the expansion of pi-conjugation. Higher-order nonlinear absorption was also observed in the former porphyrin.

Antioxidant property of metallothionein in fasted mice

Metallothionein (MT) is a low-molecular-weight and sulfur-rich protein that is induced by not only heavy metals but also physiological stresses such as fasting and restraint stresses. Although MT plays a role as a radical scavenger and a regulator of metabolism of metals, the biological function of MT induced by fasting stress has not been elucidated. In this study, we investigated the antioxidative role of MT in fasted mice. In fasted mice, the lipid peroxidation level of the liver was elevated by 24-h fasting stress, and pre-induction of hepatic MT by Zn diminished hepatic lipid peroxidation. Although 24-h fasting stress induced MT synthesis in the liver, other antioxidants such as catalase, manganese-superoxide dismutase (Mn-SOD), and glutathione peroxidase (GSHPx) were not activated in the liver. Moreover, the hepatic MT level was still elevated by fasting stress after seven cycles of repetition of alternate fasting and feeding every 24 h, but the activities of catalase, Mn-SOD and GSHPx were unchanged. These results indicate that MT induced by fasting stress plays partly as an antioxidant.

Impact of aging on the development of hepatocellular carcinoma in patients with hepatitis C virus infection in Japan

BACKGROUND

It is difficult to study the long-term outcome of hepatitis C virus (HCV) infection because chronic infection is often asymptomatic and duration of the disease is prolonged. The clinical outcome of HCV infection remains unclear in patients of advanced age.

METHODS

Among 575 patients consecutively diagnosed with hepatocellular carcinoma (HCC) from 1988 to 1999 at Hiroshima University, we examined 430 with HCV. We studied the differences between males and females in the following characteristics: age at first diagnosis of HCC, Child grade, various tumour factors, history of blood transfusion, duration to development of HCC, and history of alcohol intake.

RESULTS

The incidence of HCC patients with HCV increased in elderly persons, including female patients. Background liver function was significantly better for female patients (P < 0.001). In both genders, the duration between blood transfusion and diagnosis of HCC was significantly shorter when the patients received blood transfusion at an older age (P < 0.001). In habitual drinkers, the average age at first diagnosis of HCC was significantly younger (P < 0.001), and duration to development of HCC significantly shorter (P < 0.05). The percentage of atomic bomb survivors among HCV-positive HCC patients was significantly higher than that among HCV-negative HCC patients (P < 0.05).

CONCLUSIONS

Patients with HCV might exhibit slow disease progression and develop HCC finally with aging regardless of gender. Patients of advanced age with HCV, even female patients, should therefore be closely followed.

Property of metallothionein as a Zn pool differs depending on the induced condition of metallothionein

Metallothionein (MT) is a low-molecular-weight, cysteine-rich, heavy metal-binding protein with several putative physiological functions as a radical scavenger and a regulator of metabolism of Zn. Although the induction of hepatic MT by a wide range of stressors is a well-known phenomenon, little is known about the role of MT in stressful situations. Since MT regulates Zn metabolism, we investigated the differences between affinities of MT for Zn in various stressful conditions in this study. Divalent cadmium ions are capable of displacement of Zn from MT in vitro. Therefore, we assayed the binding of Zn to MT induced by various stimuli using in vivo administration of Cd. MT was induced by paraquat (PQ), a reactive oxygen generator, fasting stress and restraint stress. Apo-MT induced by them bound to Zn in vivo. Zn, which bound to MT induced by PQ, was displaced by the administration of Cd. However, Zn that had bound to MT induced by fasting stress and restraint stress was not displaced by Cd. Moreover, we assessed the in vivo affinity of Zn to MT induced by fasting stress under the condition of subchronic Cd exposure. Cd was administered to mice by subcutaneously implanted Alzet osmotic minipumps, which released constant amounts of Cd over a 14-day period. After 4 days, mice were fasted for 24 h and hepatic MT was examined. Interestingly, it was found that Zn had displaced Cd bound to MT. These findings indicate that the affinity of MT for Zn differs depending on the stimulus by which MT was induced. This is the first report on differences in the properties of MT depending on the stimulus used to induce MT.

Change in cytoskeletal phenotype and extracellular matrix production of muscularis mucosae during early invasive colorectal adenocarcinoma

Bundles of eosinophilic spindle cells are often found in histological preparations of the stroma of invasive colorectal adenocarcinomas. To clarify their significance, especially during the early invasive phase, we histologically and immunohistochemically studied 33 submucosally invasive colorectal adenocarcinomas in terms of their relationship with the muscularis mucosa, their cytoskeletal phenotype, and their production of extracellular matrix (ECM). Histological continuity between bundles of eosinophilic spindle cells and the muscularis mucosa was identified in 19 out of 33 adenocarcinomas (57.6%). With respect to their cytoskeletal phenotypes, the expression of alpha-smooth muscle actin (alpha-SMA) did not differ between the muscularis mucosa and the eosinophilic spindle cells, whereas the expression of desmin and high molecular weight caldesmon (h-CD) of the eosinophilic spindle cells was decreased compared with that of the muscularis mucosa (p<0.05). Definitive type I procollagen (procollagen I) expression was identified, at least in part, in 16 out of 20 (80%) areas of the eosinophilic spindle cells that were continuous with the muscularis mucosa, and in 26 out of 29 (89.7%) areas of the eosinophilic spindle cells that were not. These findings suggest that the muscularis mucosa is the origin of the eosinophilic spindle cells, that they undergo phenotypic changes separately from the smooth muscle, that is, myofibroblastic changes, and that they contribute to carcinomatous stroma formation through production of an ECM component. These findings should be taken into consideration when determining the level of submucosal invasion by colorectal adenocarcinomas.