Specific tandem GG to TT base substitutions induced by acetaldehyde are due to intra-strand crosslinks between adjacent guanine bases

Acetaldehyde is present in tobacco smoke and automotive exhaust gases, is produced by the oxidation of ethanol, and causes respiratory organ cancers in animals. We show both the types and spectra of acetaldehyde-induced mutations in supF genes in double- and single-stranded shuttle vector plasmids replicated in human cells. Of the 101 mutants obtained from the double-stranded plasmids, 63% had tandem base substitutions, of which the predominant type is GG to TT transversions. Of the 44 mutants obtained from the single-stranded plasmids, 39% had tandem mutations that are of a different type than the double-stranded ones. The GG to TT tandem substitutions could arise from intra-strand crosslinks. Our data indicate that acetaldehyde forms intra- as well as inter-strand crosslinks between adjacent two-guanine bases. Based upon the following observations: XP-A protein binds to acetaldehyde-treated DNA, DNA excision repair-deficient xeroderma pigmentosum (XP) cells were more sensitive to acetaldehyde than the repair-proficient normal cells, and a higher frequency of acetaldehyde-induced mutations of the shuttle vectors was found in XP cells than in normal cells, we propose that the DNA damage caused by acetaldehyde is removed by the nucleotide excision repair pathway. Since treatment with acetaldehyde yields very specific GG to TT tandem base substitutions in DNA, such changes can be used as a probe to identify acetaldehyde as the causal agent in human tumors.     

Immunohistochemical quantitation for extracellular matrix proteins in rats with glomerulonephritis induced by monoclonal anti-Thy-1.1 antibody

During clot retraction, platelets interact with fibrin resulting in marked reduction of clot volume. Altered fibrin structure has been reported to affect clot retraction as measured by serum expression. This study was performed to test whether such altered retraction was the result of increased resistance to network collapse or due to decreased force development by platelets. Altered fibrin structure was documented as variation of fibre mass/length ratios (mu) and shifts in clot elastic modulus. The force developed by platelets during clotting was measured directly. Increasing the fibrinogen concentration led to thinner fibre formation (decreased mu), and a linear increase in gel elastic modulus. Over a fibrinogen concentration range of 100 to 400 mg/dl, force development was minimally affected. Force development and clot elastic modulus increased in a linear fashion with increasing platelet concentration. Increasing the calcium concentration from 5 to 20 mM caused a 160% increase in fibrin fibre size (mu), and a 52% decline in clot modulus. Force developed at 1200 s declined by 17%. At 15 mg/ml, dextran and hydroxyethyl starch (HES) also increased mu, and decreased clot modulus; however, both agents markedly reduced force development. Increasing ionic strength or the addition of IgG decreased mu and increased gel elastic modulus. Force development increased modestly with increased ionic strength, did not change with addition of IgG in saline and declined with addition of IgG in maltose. This study indicates that force development is primarily dependent on platelet function while clot modulus depends on both fibrin structure and platelet function.(ABSTRACT TRUNCATED AT 250 WORDS)     

Involvement of PACAP in acid-induced HCO3- response in rat duodenums

A case of Ewing's sarcoma of the bone, arising in the right radius of a 12-year-old girl, which showed unique histologic features after pre-operative treatment, is reported. The light microscopic features of a biopsy sample were those of a small round cell tumor showing positive immunoreaction with antibodies against the product of the MIC 2 gene (O13), neuron-specific enolase, neurofilament, and synaptophysin, but no morphological differentiation. The patient received combined intensive multi-drug chemotherapy and radiation before surgery. Examination of the surgical specimen showed that the tumor was less cellular than that in the biopsy specimen, and was composed mainly of loosely textured large cells mimicking ganglion cells, occasionally forming Homer-Wright rosettes. An immunohistochemical study revealed that neural differentiation was enhanced. Immunoreactivity for Leu-7 also became positive. Although the patient underwent postoperative chemotherapy, she died of multiple lung and bone metastases 30 months after the diagnosis. Autopsy showed that metastatic foci were made up of densely packed small round cells like those seen in the biopsy samples, but associated with prominent Homer-Wright rosettes. To the authors' knowledge, this is the first report of a tumor being replaced almost entirely by ganglion cells after pre-operative chemotherapy and radiotherapy.     

Dendrimer-immobilized culture surface as a tool to evaluate formation of cellular cytoskeleton of anchorage-dependent cells

Anchorage-dependent cultivation of human epithelial and keratinocyte cells was carried out on surfaces modified with synthesized dendrimers. Notable elongation of the epithelial cells was recognized on the culture surface immobilized with a dendrimer having D-glucose as a functional ligand, but not when a dendrimer having L-glucose was used or when the dendrimer was ligand-free. This morphological change was attributable to a temporary grasping of the cells at the D-glucose moiety via a glucose transporter-mediated mechanism present in the cell membrane. Following visualization of the actin filaments of the cells, it was considered that the cellular elongation on the D-glucose-bound dendrimer surface reflected the degree of formation of the cellular cytoskeleton. The cellular roundness was calculated by means of image analysis of the individual cells and employed as a parameter to evaluate the formation of the cellular cytoskeleton. In the culture of keratinocytes on the D-glucose-bound dendrimer surface, it was demonstrated that the decrease in the ratio of elongated cells (i.e., cells with a low roundness value) was correlated with the deterioration in the growth potential associated with cellular senescence.     

Multi-rigid-body dynamics and online model predictive control for transformable multi-links aerial robot*

Transformable multi-links aerial robots have great potentials in application relying on the transformable features to change its shape during the flight. Compared to traditional quadrotor robots, transformable multi-links robots are equipped with servo motor between links. To simplify the non-linear dynamic system, the previous work restricts the robot to transform in very slow speed so that the robot could be approximated as a quadrotor robot at each time point. However, tradeoff comes as the dynamic performance is given up. In this paper, we come up with a new framework combining of computationally efficient non-linear model predictive controller and motion primitive to optimize thrust force and joints trajectory of the multi-links aerial robot. Finally, we verify our framework with fast transformation motions and table tennis task which requires dynamic performance.     

Shear properties of metal-free wooden load-bearing walls using plywood jointed with a combination of adhesive tape and wood dowels

In this study, the potential of wood-only (metal-free) load-bearing walls was proposed and tested based on the idea of using the same type of material throughout wherever possible while improving basic properties such as strength, sound insulation, and heat insulation. Specifically, a technique was tested of combining pressure sensitive adhesive tape and wood dowels in place of nails for load-bearing structures with panel reinforcement represented by wood-frame construction. For this paper, its strength was evaluated by conducting in-plane shear tests, which revealed that the initial rigidity and maximum load of the proposed test specimens were greater than that of specimens using nails for jointing. However, the shear load factor, which is calculated based on some strength parameters and which forms the foundation of housing strength design, was slightly lower than that of the nail-jointed specimen. This was because there was a large decline in post-collapse resistance and a lower calculated absorbed energy caused by brittleness. The early detachment of panels was also revealed as a problem in the tests.     

Anaerobic Biodegradation Tests of Poly(lactic acid) under Mesophilic and Thermophilic Conditions Using a New Evaluation System for Methane Fermentation in Anaerobic Sludge

Anaerobic biodegradation tests of poly(lactic acid) (PLA) powder were done at the thermophilic (55 °C) and mesophilic temperature (35 °C) under aquatic conditions [total solid concentrations of the used sludge were 2.07% (at 55 °C) and 2.24% (at 35 °C)] using a newly developed evaluation system. With this system, the evolved biogas is collected in a gas sampling bag at atmospheric pressure. This method is more convenient than using a pressure transducer or inverted graduated cylinder submerged in water. PLA was degraded about 60% in 30 days, about 80% in 40 days and about 90% in 60 days at 55 °C. On the other hand, the PLA degradation started in 55 days at 35 °C and degradation rate was much slower than at 55 °C.     

Distractor devaluation effect in the attentional blink: Direct evidence for distractor inhibition.

When two targets (T1 and T2) are embedded in rapid serial visual presentation (RSVP), T2 is often missed (attentional blink, AB) if T2 follows T1 by less than 500 ms. Some have proposed that inhibition of a distractor following T1 contributes to the AB, but no direct evidence supports this proposal. This study examined distractor inhibition by assessing a distractor devaluation effect where inhibited items were evaluated less positively than controls. Experiments 1 and 2 showed that a distractor presented just after T1 was evaluated less favorably when T2 was misidentified, independently of stimulus characteristics. Experiment 3 produced distractor devaluation in T2 incorrect trials when the evaluated distractor was the second item after T1. In contrast, a distractor presented before T1 was not devaluated (Experiment 4). Experiment 5 demonstrated that participants could not recognize presented distractors after an RSVP task, rejecting the possibility that memorized distractors were devalued. Results show a relationship between the devaluation of distractors following T1 and the AB, providing the first direct evidence of the distractor inhibition during the AB. (PsycINFO Database Record (c) 2010 APA, all rights reserved)