This study compared two test methods used to evaluate the flexural strength of resin-based dental composites. The two test methods evaluated were the three-point bending test4 and the biaxial flexural test. Materials used in this investigation were from the same manufacturer (3M ESPE) and included microfill (A110), minifill (Z100 and Filtek Z250), polyacid modified (F2000), and flowable [Filtek Flowable (FF)] composites. Flexural strength was determined with the use of both test methods after 1 week of conditioning in water at 37 degrees C. Data were analyzed with the use of an ANOVA/Scheffe test and an independent-samples t test at significance level 0.05. Mean flexural strength (n = 7) ranged from 66.61 to 147.21 and 67.27 to 182.81 MPa for three-point bending and ball-on-three-ball biaxial test methods, respectively. In both test methods, Z100 was significantly stronger than all other composites evaluated. In the three-point bending test, flexural strength of Z250 was significantly higher than A110, F2000 and FF, and FF was significantly stronger than A110 and F2000. The biaxial test method arrived at the same conclusions except that there was no significant difference between Z250 and FF. Pearson's correlation revealed a significantly (p < 0.01) positive and good correlation (R2 = 0.72) in flexural strength between the two test methods. Although the biaxial test has the advantage of utilizing small specimens, the low reproducibility of this test method does not support the proposition that it is a more reliable test method when compared to the ISO three-point bending test.

The population structure of the Bacillus cereus group (52 strains of B. anthracis, B. cereus, and B. thuringiensis) was investigated by sequencing seven gene fragments (rpoB, gyrB, pycA, mdh, mbl, mutS, and plcR). Most of the strains were classifiable into two large subgroups in six housekeeping gene trees but not in the plcR tree. In addition, several consistent clusters were identified, which were unrelated to species distinction. Moreover, interrelationships among these clusters were incongruent in each gene tree. The incongruence length difference test and split decomposition analyses also showed incongruences between genes, suggesting horizontal gene transfer. The plcR gene was observed to have characteristics that differed from those of the other genes in terms of phylogenetic topology and pattern of sequence diversity. Thus, we suggest that the evolutionary history of the PlcR regulon differs from those of the other chromosomal genes and that recombination of the plcR gene may be frequent. The homogeneity of B. anthracis, which is depicted as an independent lineage in phylogenetic trees, is suggested to be of recent origin or to be due to the narrow taxonomic definition of species.The Bacillus cereus group, which is a subdivision of the genus Bacillus, includes the closely related species Bacillus anthracis, Bacillus cereus, and Bacillus thuringiensis (22). However, their pathogenic potentials and disease spectrums are quite different despite their genetic relatedness. B. cereus is an opportunistic pathogen and causes several types of infections in humans. It is frequently isolated as a contaminant of milk, cereals, and various other foods, and it produces an emetic toxin and one or several enterotoxins. On the other hand, B. thuringiensis is primarily an insect pathogen, and it produces intracellularly insecticidal crystal toxins of different specificities during sporulation or in the stationary phase, which is the only established difference between it and B. cereus (7). B. anthracis causes the potentially lethal disease anthrax, and it has been identified as a nonhemolytic, nonmotile, penicillin-sensitive, encapsulated bacterium. B. anthracis is important in that it is considered a potential biological weapon (26). The genes causing the lethal effect of anthrax are located on two large virulence plasmids, pXO1 and pXO2 (26).The genomes of these three species show high levels of similarity; for example, they share almost identical 16S ribosomal DNA sequences (2), although an association of a distinct type of 16S ribosomal DNA sequence with B. anthracis was recently reported (30). Although several phenotypes (such as capsule, lack of hemolysis, lack of motility, and susceptibility to gamma phage) and biochemical tests can differentiate B. anthracis from B. cereus and B. thuringiensis (38), species delimitation is unclear. In fact, they were suggested to be one species based on a multilocus enzyme electrophoresis (MLEE) result (14) and by the presence of an S-layer on the cell surface (24). Therefore, an ...

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When we treated rat bone marrow stromal cells (rBMSCs) with neuronal differentiation induction media, typical unfolded protein response (UPR) was observed. BIP/GRP78 protein expression was time-dependently increased, and three branches of UPR were all activated. ATF6 increased the transcription of XBP1 which was successfully spliced by IRE1. PERK was phosphorylated and it was followed by eIF2α phosphorylation. Transcription of two downstream targets of eIF2α, ATF4 and CHOP/GADD153, were transiently up-regulated with the peak level at 24 h. Immunocytochemical study showed clear coexpression of BIP and ATF4 with NeuN and Map2, respectively. UPR was also observed during the neuro-