Quantitative Analysis of Diepoxybutane Damage within the Chicken β-globin Domain

In industrial polymer and synthetic rubber production facilities, workers are exposed to 1,3-butadiene. This compound is converted in vivo to 1,2,3,4-diepoxybutane (DEB) and has been linked to increased incidences of cancer in these individuals. Carcinogenesis has been attributed to formation of DEB induced DNA interstrand cross-links. Previous studies have demonstrated that DEB cross-links deoxyguanosine residues within 5'-GNC sequences in synthetic DNA, in restriction fragments, and in defined sequence nucleosomes. The current study utilized the polymerase chain reaction (PCR) to examine DEB damage frequencies within nuclear genes, found within "open" regions of chromatin, as compared to regions of unexpressed sequence that reside in tightly packed, "closed" chromatin, to more closely model DEB reactivity in vivo. These initial studies have been performed in chicken liver homogenates. Preliminarily, we have found a dose-dependent DEB lesion-forming response within "open" chromatin. DEB appears to have little-to-no effect upon regions of "closed" chromatin.

Mapping of Diepoxybutane Damage in the Cytochrome b Domain of Mitochondrial DNA and the β-globin Domain of Nuclear Chicken DNA Using Quantitative PCR

Diepoxybutane (DEB), a known industrial carcinogen, reacts with DNA primarily at the N7 position of deoxyguanosine residues and creates interstrand cross-links at the sequence 5'-GNC. Since N7-N7 cross-links cause DNA to fragment upon heating, quantative polymerase chain reaction (QPCR) is being used in this experiment to measure the amount of DEB damage (lesion frequency) with three different targets-mitochondrial (unpackaged), open chromatin region, and closed chromatin region. Initial measurements of DEB damage within these three targets were not consistent because the template DNA was not the limiting reagent in the PCR. Follow-up PCR trials using a limiting amount of DNA are still in progress although initial experimentation looks promising. Sequencing of these three targets to confirm the primer targets has only been successfully performed for the closed chromatin target and does not match the sequence from NIH used to design that primer pair. Further sequencing trials need to be conducted on all three targets to assure that a mitochondrial, open chromatin, and closed chromatin region are actually being amplified in this experimental series.

Fine root isotropy in Eucalyptus grandis plantations. Towards the prediction of root length densities from root counts on trench walls

The objectives of the study were to assess changes in fine root anisotropy and specific root lengths throughout the development of Eucalyptus grandis ( W. Hill ex Maiden) plantations and to establish a predictive model of root length density (RLD) from root intercept counts on trench walls. Fine root densities (<1 mm in diameter) were studied in 6-, 12-, 22-, 28-, 54-, 68- and 72-month-old E. grandis plantations established on deep Ferralsols in southern Brazil. Fine root intercepts were counted on 3 faces of 90-198 soil cubes (1 dm(3) in volume) in each stand and fine root lengths (L) were measured inside 576 soil cubes, sampled between the depths of 10 cm and 290 cm. The number of fine root intercepts was counted on one vertical face perpendicular to the planting row (N(t)), one vertical face parallel to the planting row (N(l)) and one horizontal face (N(h)), for each soil cube sampled. An overall isotropy of fine roots was shown by paired Student's t-tests between the numbers of fine roots intersecting each face of soil cubes at most stand ages and soil depths. Specific root lengths decreased with stand age in the upper soil layers and tended to increase in deep soil layers at the end of the rotation. A linear regression established between N(t) and L for all the soil cubes sampled accounted for 36% of the variability of L. Such a regression computed for mean Nt and L values at each sampling depth and stand age explained only 55% of the variability, as a result of large differences in the relationship between L and Nt depending on stand productivity. The equation RLD=1.89*LAI*N(t), where LAI was the stand leaf area index (m(2) m(-2)) and Nt was expressed as the number of root intercepts per cm(2), made it possible to predict accurately (R(2)=0.84) and without bias the mean RLDs (cm cm(-3)) per depth in each stand, for the whole data set of 576 soil cubes sampled between 2 years of age and the end of the rotation.

Time-domain analysis of piezoelectric impedance-based structural health monitoring using multilevel wavelet decomposition

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

A multisampling time-domain CMOS imager with synchronous readout circuit

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Probing bilinear R-parity violating supergravity at the LHC

We study the collider phenomenology of bilinear R-parity violating supergravity, the simplest effective model for supersymmetric neutrino masses accounting for the current neutrino oscillation data. At the CERN Large Hadron Collider the center-of-mass energy will be high enough to probe directly these models through the search for the superpartners of the Standard Model (SM) particles. We analyze the impact of R-parity violation on the canonical supersymmetry searches-that is, we examine how the decay of the lightest supersymmetric particle (LSP) via bilinear R-parity violating interactions degrades the average expected missing momentum of the reactions and show how this diminishes the reach in the usual channels for supersymmetry searches. However, the R-parity violating interactions lead to an enhancement of the final states containing isolated same-sign di-leptons and trileptons, compensating the reach loss in the fully inclusive channel. We show how the searches for displaced vertices associated to LSP decay substantially increase the coverage in supergravity parameter space, giving the corresponding reaches for two reference luminosities of 10 and 100 fb(-1) and compare with those of the R-parity conserving minimal supergravity model.

A BEM formulation for analysing the coupled stretching-bending problem of plates reinforced by rectangular beams with columns defined in the domain

In this work, a boundary element formulation to analyse plates reinforced by rectangular beams, with columns defined in the domain is proposed. The model is based on Kirchhoff hypothesis and the beams are not required to be displayed over the plate surface, therefore eccentricity effects are taken into account. The presented boundary element method formulation is derived by applying the reciprocity theorem to zoned plates, where beams are treated as thin sub-regions with larger rigidities. The integral representations derived for this complex structural element consider the bending and stretching effects of both structural elements working together. The standard equilibrium and compatibility conditions along interface are naturally imposed, being the bending tractions eliminated along interfaces. The in-plane tractions and the bending and in-plane displacements are approximated along the beam width, reducing the number of degrees of freedom. The columns are introduced into the formulation by considering domain points where tractions can be prescribed. Some examples are then shown to illustrate the accuracy of the formulation, comparing the obtained results with other numerical solutions.

The central repeat domain 1 of Kaposi's sarcoma-associated herpesvirus (KSHV) latency associated-nuclear antigen 1 (LANA1) prevents cis MHC class I peptide presentation

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Effect of Conventional and Resin-modified Glass-Ionomer Liner on Dentin Adhesive Interface of Class I Cavity Walls After Thermocycling

Objective: The aim of this in vitro study was to analyze the effect of glass-ionomer cement as a liner on the dentin/resin adhesive interface of lateral walls of occlusal restorations after thermocycling.Materials and Methods: Occlusal cavities were prepared in 60 human molars, divided into six groups: no liner (1 and 4); glass-ionomer cement (GIC, Ketac Molar Easymix, 3M ESPE) (2 and 5); and resin-modified glass-ionomer cement (RMGIC, Vitrebond, 3M ESPE) (3 and 6). Resin composite (Filtek Z250, 3M ESPE) was placed after application of an adhesive system (Adper Single Bond 2, 3M ESPE) that was mixed with a fluorescent reagent (Rhodamine B) to allow confocal microscopy analysis. Specimens of groups 4, 5 and 6 were thermocycled (5 degrees C-55 degrees C) with a dwell time of 30 seconds for 5000 cycles. After this period, teeth were sectioned in approximately 0.8-mm slices. One slice of each tooth was randomly selected for confocal microscopy analysis. The other slices were sectioned into 0.8 nun x 0.8 mm beams, which were submitted to microtensile testing (MPa). Data were analyzed using two-way ANOVA and Tukey test (p < 0.05).Results: There was no detectedstatistical difference on bond strength among groups (alpha < 0.05). Confocal microscopy analysis showed a higher mean gap size in group 4(12.5 mu m) and a higher percentage of marginal gaps in the thermocycled groups. The RNIGIC liner groups showed the lowest percentage of marginal gaps.Conclusions: Lining with RMGIC resulted in less gap formation at the dentin/resin adhesive interface after artificial aging. RMGIC or GIC liners did not alter the microtensile bond strength of adhesive system/resin composite to dentin on the lateral walls of Class I restorations.

Efficacy of NiTi rotary instruments in removing calcium hydroxide dressing residues from root canal walls

The aim of this study was to evaluate the efficacy of three rotary instrument systems (K3, ProTaper and Twisted File) in removing calcium hydroxide residues from root canal walls. Thirty-four human mandibular incisors were instrumented with the ProTaper System up to the F2 instrument, irrigated with 2.5% NaOCl followed by 17% EDTA, and filled with a calcium hydroxide intracanal dressing. After 7 days, the calcium hydroxide dressing was removed using the following rotary instruments: G1 - NiTi size 25, 0.06 taper, of the K3 System; G2 - NiTi F2, of the ProTaper System; or G3 - NiTi size 25, 0.06 taper, of the Twisted File System. The teeth were longitudinally grooved on the buccal and lingual root surfaces, split along their long axis, and their apical and cervical canal thirds were evaluated by SEM (×1000). The images were scored and the data were statistically analyzed using the Kruskall Wallis test. None of the instruments removed the calcium hydroxide dressing completely, either in the apical or cervical thirds, and no significant differences were observed among the rotary instruments tested (p > 0.05).

LaTBP1: A Leishmania amazonensis DNA-binding protein that associates in vivo with telomeres and GT-rich DNA using a Myb-like domain

Different species of Leishmania can cause a variety of medically important diseases, whose control and treatment are still health problems. Telomere binding proteins (TBPs) have potential as targets for anti-parasitic chemotherapy because of their importance for genome stability and cell viability. Here, we describe LaTBP1 a protein that has a Myb-like DNA-binding domain, a feature shared by most double-stranded telomeric proteins. Binding assays using full-length and truncated LaTBP1 combined with spectroscopy analysis were used to map the boundaries of the Myb-like domain near to the protein only tryptophan residue. The Myb-like domain of LaTBP1 contains a conserved hydrophobic cavity implicated in DNA-binding activity. A hypothetical model helped to visualize that it shares structural homology with domains of other Myb-containing proteins. Competition assays and chromatin immunoprecipitation confirmed the specificity of LaTBP1 for telomeric and GT-rich DNAs, suggesting that LaTBP1 is a new TBP. (C) 2007 Elsevier B.V. All rights reserved.

The Saccharomyces cerevisiae COQ10 gene encodes a START domain protein required for function of coenzyme Q in respiration

Deletion of the Saccharomyces cerevisiae gene YOL008W, here referred to as COQ10, elicits a respiratory defect as a result of the inability of the mutant to oxidize NADH and succinate. Both activities are restored by exogenous coenzyme Q(2). Respiration is also partially rescued by COQ2, COQ7, or COQ8/ABC1, when these genes are present in high copy. Unlike other coq mutants, all of which lack Q(6), the coq10 mutant has near normal amounts of Q(6) in mitochondria. Coq10p is widely distributed in bacteria and eukaryotes and is homologous to proteins of the aromatic-rich protein family Pfam03654 and to members of the START domain superfamily that have a hydrophobic tunnel implicated in binding lipophilic molecules such as cholesterol and polyketides. Analysis of coenzyme Q in polyhistidine-tagged Coq10p purified from mitochondria indicates the presence 0.032-0.034 mol of Q(6)/mol of protein. We propose that Coq10p is a Q(6)-binding protein and that in the coq10 mutant Q(6) it is not able to act as an electron carrier, possibly because of improper localization.