TEGDMA-induced oxidative DNA damage and activation of ATM and MAP kinases

The development of strategies for the protection of oral tissues against the adverse effects of resin monomers is primarily based on the elucidation of underlying molecular mechanisms. The generation of reactive oxygen species beyond the capacity of a balanced redox regulation in cells is probably a cause of cell damage. This study was designed to investigate oxidative DNA damage, the activation of ATM, a reporter of DNA damage, and redox-sensitive signal transduction through mitogen-activated protein kinases (MAPKs) by the monomer triethylene glycol dimethacrylate (TEGDMA). TEGDMA concentrations as high as 3-5 mm decreased THP-1 cell viability after a 24 h and 48 h exposure, and levels of 8-oxoguanine (8-oxoG) increased about 3- to 5-fold. The cells were partially protected from toxicity in the presence of N-acetylcysteine (NAC). TEGDMA also induced a delay in the cell cycle. The number of THP-1 cells increased about 2-fold in G1 phase and 5-fold in G2 phase in cultures treated with 3-5 mm TEGDMA. ATM was activated in THP-1 cells by TEGDMA. Likewise, the amounts of phospho-p38 were increased about 3-fold by 3 mm TEGDMA compared to untreated controls after a 24 h and 48 h exposure period, and phospho-ERK1/2 was induced in a very similar way. The activation of both MAPKs was inhibited by NAC. Our findings suggest that the activation of various signal transduction pathways is related to oxidative stress caused by a resin monomer. Signaling through ATM indicates oxidative DNA damage and the activation of MAPK pathways indicates oxidative stress-induced regulation of cell survival and apoptosis. (C) 2008 Elsevier Ltd. All rights reserved.

Metabolic adaptations induced by long-term fasting in quails

After up to 21 days without food, adult male quails (Coturnix coturnix japonica) lost about 45% of the initial body weight (100-150 g). As in naturally fast-adapted and larger birds, three phases were identified during prolonged fasting in quails. Phase I lasted 2-3 days and was characterized by a rapid decrease in the rate of body weight loss and high fat mobilization. Phase II was longer and characterized by a slow and steady decline in the rates of body weight loss and of nitrogen excretion. The third (critical) period was marked by an abrupt increase in the rates of body weight loss and of nitrogen excretion. Despite their small size, the duration of phase II in quails was relatively long, a clear advantage for the study of the relationships between the several metabolic events that occur during this crucial adaptative period. Also, the beginning of phase III could be precisely determined. Changes in blood glucose, plasma FFA and triacylglycerols levels, as well as in liver and carcass lipid content were similar to those found in other species of birds. Therefore, quails seem to be a suitable model to investigate the biochemical mechanisms involved in the metabolic adjustments to prolonged food deprivation in non fasting-adapted birds. © 1995.

Protective effect of safranine on the mitochondrial damage induced by Fe(II)citrate: Comparative study with trifluoperazine

In this study, we show that safranine at the concentrations usually employed as a probe of mitochondrial membrane potential significantly protects against the oxidative damage of mitochondria induced by Fe(II)citrate. The effect of safranine was illustrated by experiments showing that this dye strongly inhibits both production of thiobarbituric acid-reactive substances and membrane potential decrease when energized mitochondria were exposed to Fe(II)citrate in the presence of Ca 2+ ions. Similar results were obtained with the lipophylic compound trifluoperazine. It is proposed that, like trifluoperazine, safranine decreases the rate of lipid peroxidation due to its insertion in the membrane altering the physical state of the lipid phase.

Chromosome damage induced by 5-azacytidine under the influence of caffeine or cytosine arabinoside in CHO-K1 (wild-type) and XRS-5 (mutant) cell lines

5-azacytidine (5-azaC) treatment combined with cytosine arabinoside (ara-C) or caffeine were performed in vitro in Chinese hamster cells, CHO-K1 (wild-type) and xrs-5 (mutant) cell lines, in order to compare the cell response to the induction of chromosomal aberrations. Exponentially growing cells were treated with 5-azaC (4-16 uM) for 1 h, the cells were washed and incubated for 7 h, and 500 uM caffeine or 5 uM ara-C were added to the cultures for the last 2 h. In both cell lines, 5-azaC induced a significantly increase (P<0.01) in the frequencies of aberrations; in the combined treatments (5-azaC + Ara-C), a significant reduction (P<0.05) was observed for the aberrations which were randomly distributed. Caffeine had no influence at the same conditions. 5-azaC induced-DNA lesions were probably processed at S/G2 phase in a common pathway in both cell lines, but alternatively, 5-azaC may cause xrs-5 cells to revert to the wild-type.

Light-induced electric dipole relaxation in synthetic and natural alexandrite

We present results of thermally stimulated depolarization current (TSDC) measurements in synthetic and natural alexandrite, which show TSDC bands related to the presence of electric dipoles in both types of samples. Synthetic material shows a wide TSDC band with a peak at 179 K, which can be fitted by two distinct relaxing dipole distributions. For natural alexandrite the TSDC band has a maximum around 195 K and can be fitted by three different distributions. Both samples present one of the calculated curves with a peak about 179 K, with activation energy of 0.57 eV and constant relaxation time of 1 × 10-14 sec. Photo-induced TSDC shows that TSDC bands can also be generated by simultaneous application of light and an electric field at 77 K.

In vitro propagation of Maytenus ilicifolia (Celastraceae) as potential source for antitumoral and antioxidant quinomethide triterpenes production. A rapid quantitative method for their analysis by reverse-phase high-performance liquid chromatography

Cell culture of Maytenus ilicifolia were established in order to produce and to quantify the antitumoral and antioxidant quinonemethide triterpenes. In vitro calli were induced from leaf explants of native plants and cultured in semi-solid medium under controlled conditions of humidity, temperature and photoperiod. The quinonemethide triterpenes showed maximum accumulation in the logarithmic phase growth of the cell culture. A rapid, sensitive and reliable reverse-phase HPLC method was used for quantitative determination of the antitumoral and antioxidant quinonemethide triterpenes, 22β-hydroxymaytenin and maytenin in callus of Maytenus ilicifolia. Well resolved peaks with good detection response and linearity in the range 1.0 - 100 μg/mL were obtained. This quantitative work was performed by an external standard method.

Phase transformations in the Cu-Al alloy with Ag addition

The effect of Ag addition on the phase transformations that occur in the Cu-10% Al alloy was studied using differential thermal analysis, scanning electron and optical microscopies and energy dispersive X-ray analysis. The results indicated that Ag addition is responsible for the separation of the reverse martensitic transformation in two stages, and for the refinement of the α-phase grains. The relative amount of the β1 martensitic phase, retained on slow cooling (above 2 K min-1 of cooling rate), and the relative fraction of phase α2 are increased. The solubility limit of Ag in the matrix is close to 6 mass% and at this concentration the maximum stability of the β-phase is reached. © 2005 Akadémiai Kiadó, Budapest.

The investigation of α→β phase transition in poly(vinylidene fluoride) (PVDF)

The phase transition from the non-polar α-phase to the polar β-phase of poly(vinylidene fluoride) (PVDF) has been investigated using micro-Raman spectroscopy, which is advantageous for being a non-destructive technique. Films of α-PVDF were subjected to stretching under controlled rates and at 80°C, the transition to β-PVDF being monitored by the decrease in the Raman band at 794 cm-1 characteristic of the α-phase, with the concomitant increase in the 839 cm-1 band characteristic of the β-phase. Poling with negative corona discharge was found to affect the a-PVDF morphology improving the Raman bands related to this crystalline phase. This effect is minimized for films stretched to higher ratios. Significantly, corona-induced effects could not be observed with the other experimental techniques, viz. X-ray diffraction and infrared spectroscopy.

Oral stomatitis induced by endogenous progesterone: Case report

Oral stomatitis induced by endogenous progesterone is a rare clinical condition which may be associated with cutaneous involvement. That is probably due to the peak of progesterone production during the luteal phase of the menstrual cycle. In the present case report, a 21-year-old patient displayed recurrent ulcerative lesions located on the buccal mucosa or the upper lip, on a monthly basis since the age of 15. Such lesions would always manifest themselves on the second day until the end of the menstrual cycle. © 2009 Informa UK Ltd All rights reserved.

Measurement of phase and amplitude modulations in Sb-Based Films

In this work we studied the changes of the optical constants of films in the binary system Sb2O3-Sb2S3 induced by light in the VIS-UV. The measurements were performed before and after homogeneous irradiation of the films to a Hg lamp and in real time during the holographic exposure of the samples (at 458nm). Changes of the absorption coefficient (amplitude grating) and refractive index (phase grating) were measured simultaneously using the self-diffraction using the holographic setup. Besides the films presented a strong photodarkening effect under homogeneous irradiation, the samples holographically exposed presented only refractive index modulations. None amplitude modulation was measured in real time for spatial frequencies of about 1000 l/mm. © 2009 SPIE.

Effects of fatigue induced by prolonged gait when walking on the elderly

Purpose. Fatigue has been pointed as a fall risk in the elderly; however, the effects of prolonged gait on neuromuscular recruitment and on its pattern remain unknown. The aim of this study was to evaluate the effects of prolonged gait on neuromuscular recruitment levels and spatial-temporal gait variables. Methods. Eight healthy older women (age: 72.63 ± 6.55 years) walked at their preferred walking speed for twenty minutes on a treadmill. The Root Mean Square (RMS) from the vastus-lateralis, femoral biceps, tibialis anterior and lateral gastrocnemius muscles were determined at the first and last minute of the test during the moments of Heel Strike (HS), Terminal Stance and Terminal Swing (TS). In addition, coactivation in the knee and ankle as well as the stride cadence and length were measured in the test. The two RMS data (taken at the first and last minute) were compared by means of a Student's t-test. Results. Twenty minutes of walking induced fatigue in the subjects, as observed through an increase in RMS, notably during the HS and TS. Coactivation was also influenced by the prolonged gait test. The only gait phase where a risk of falling was enhanced was the HS. Nonetheless, subjects developed strategies to maintain a safe motor pattern, which was evidenced by an increase in stride length and a decrease in stride cadence. Conclusion. Tests lasting just twenty minutes on a treadmill were enough to induce fatigue in older adults. However, the level of fatigue was not enough to present a danger or fall risk to elderly individuals.

Field-induced length changes in the spin-liquid candidate κ-(BEDT-TTF) 2Cu 2(CN) 3

Measurements of the coefficient of thermal expansion on the spin-liquid candidate κ-(BEDT-TTF) 2Cu 2(CN) 3 have revealed distinct and strongly anisotropic lattice effects around 6 K - a possible spin liquid instability. In order to study the effects of a magnetic field on the low-temperature spin-liquid state, dilatometric measurements have been conducted both as a function of temperature at B = const. and as a function of field at T = const. While the 6 K anomaly is found to be insensitive to magnetic fields B ≤ 10 T, the maximum field applied, surprisingly strong B -induced effects are observed for magnetic fields applied along the in-plane b-axis. Above a threshold field of 0.5 T < B c ≤ 1 T, a jump-like anomaly is observed in the b-axis lattice parameter. This anomaly, which is located at 8.7 K at B = 1 T, grows in size and shifts to lower temperatures with increasing the magnetic field. Although the anomaly bears resemblance to a first-order phase transition, the lack of hysteresis suggests otherwise. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A transmission line model developed directly in phase domain

The phases of a transmission line are tightly coupled due to mutual impedances and admittances of the line. One way to accomplish the calculations of currents and voltages in multi-phase lines consists in representing them in modal domain, where its n coupled phases are represented by their n propagation modes. The separation line in their modes of propagation is through the use of a modal transformation matrix whose columns are eigenvectors associated with the parameters of the line. Usually, this matrix is achieved through numerical methods which do not allow the achievement of an analytical model for line developed directly in the phases domain. This work will show an analytical model for phase currents and voltages of the line and results it will be applied to a hypothetical two-phase. It will be shown results obtained with that will be compared to results obtained using a classical model. © 2012 IEEE.

Decay of photo-induced conductivity in Sb-doped SnO2 thin films, using monochromatic light of about bandgap energy

Doping tin dioxide (SnO2) with pentavalent Sb5+ ions leads to an enhancement in the electrical conductivity of this material, because Sb5+ substitutes Sn4+ in the matrix, promoting an electronic density increase in the conduction band, due to the donor-like nature of the doping atom. Results of computational simulation, based on the Density Functional Theory (DFT), of SnO2:4%Sb and SnO2:8%Sb show that the bandgap magnitude is strongly affected by the doping concentration, because the energy value found for 4 at%Sb and 8 at%Sb was 3.27 eV and 3.13 eV, respectively, whereas the well known value for undoped SnO2 is about 3.6 eV. Sb-doped SnO2 thin films were obtained by the sol-gel-dip-coating technique. The samples were submitted to excitation with below theoretical bandgap light (450 nm), as well as above bandgap light (266 nm) at low temperature, and a temperature-dependent increase in the conductivity is observed. Besides, an unusual temperature and time dependent decay when the illumination is removed is also observed, where the decay time is slower for higher temperatures. This decay is modeled by considering thermally activated cross section of trapping centers, and the hypothesis of grain boundary scattering as the dominant mechanism for electronic mobility. © 2012 Elsevier B.V. All rights reserved.

Chemoprotective activity of the isoflavones, genistein and daidzein on mutagenicity induced by direct and indirect mutagens in cultured HTC cells

Isoflavones are phenolic compounds widely distributed in plants and found in a high percentage in soybeans. They have important biological properties and are regarded as potential chemopreventive agents. The aim of this study was to verify the preventive effect of two soy isoflavones (genistein and daidzein) by a micronucleus assay, analysis of GST activity, and real-time RT-PCR analysis of GSTa2 gene expression. Mutagens of direct (doxorubicin) and indirect (2-aminoanthracene) DNA damage were used. Hepatoma cells (HTC) were treated with genistein or daidzein for 26 h at noncytotoxic concentrations; 10 μM when alone, and 0.1, 1.0 and 10 μM when combined with genotoxic agents. The micronucleus test demonstrated that both isoflavones alone had no genotoxic effect. Genistein showed antimutagenic effects at 10 μM with both direct and indirect DNA damage agents. On phase II enzyme regulation, the current study indicated an increase in total cytoplasmic GST activity in response to genistein and daidzein at 10 μM supplementation. However, the mRNA levels of GSTa2 isozymes were not differentially modulated by genistein or daidzein. The results point to an in vitro antimutagenic activity of genistein against direct and indirect DNA damage-induced mutagenicity. © 2012 Springer Science+Business Media B.V.