p53, p63 and p73 expression and angiogenesis in keratocystic odontogenic tumors

Keratocystic odontogenic tumors (KCOTSs) are odontogenic tumors previously referred to as odontogenic keratocysts. Several studies have reported that KCOT behavior is more like that of a benign neoplasm than a cyst. KCOTs are locally destructive and exhibit a high recurrence rate. The objective of this study is to characterize the expression of p53, p63 and p73 in KCOTs together with the relationship between their expression and KCOT angiogenesis and recurrence. Standard indirect immunohistochemistry using monoclonal antibodies specific to human p53, p63, p73 and CD105 was performed in formalin-fixed paraffin-embedded tissue sections of 39 KCOT samples. Grading of p53, p63 and p73 immunohistochemical staining was divided into three groups, whereas microvessel density (MVD) was presented as the mean +/- standard deviation. Associations between p53, p63 and p73 expression and clinical-pathological parameters were analyzed by Fisher’s exact test, whereas associations among MVD levels, clinical and pathological parameters and p53, p63 and p73 expression were analyzed by the Mann-Whitney U test. Correlations among p53, p63, p73 and MVD levels were analyzed using Spearman’s correlation coefficients. For all analyses, p< 0.05 was considered to indicate statistical significance. p53, p63 and p73 expression was noted in 23, 32 and 26 of 39 KCOT cases, respectively. The mean MVD was 26.7 ± 15.8 per high-power field. In addition, correlations between the expression levels of p53, p63, p73 and MVD in KCOT were examined. Statistically significant positive relationships were noted for all proteins (p<0.001). Three members of the p53 protein family are expressed in KCOTs, and their expression relates to angiogenesis in these tumors

The Role of Bacillithiol in Gram-Positive Firmicutes

Significance: Since the discovery and structural characterization of bacillithiol (BSH), the biochemical functions of BSH-biosynthesis enzymes (BshA/B/C) and BSH-dependent detoxification enzymes (FosB, Bst, GlxA/B) have been explored in Bacillus and Staphylococcus species. It was shown that BSH plays an important role in detoxification of reactive oxygen and electrophilic species, alkylating agents, toxins, and antibiotics. Recent Advances: More recently, new functions of BSH were discovered in metal homeostasis (Zn buffering, Fe-sulfur cluster, and copper homeostasis) and virulence control in Staphylococcus aureus. Unexpectedly, strains of the S. aureus NCTC8325 lineage were identified as natural BSH-deficient mutants. Modern mass spectrometry-based approaches have revealed the global reach of protein S-bacillithiolation in Firmicutes as an important regulatory redox modification under hypochlorite stress. S-bacillithiolation of OhrR, MetE, and glyceraldehyde-3-phosphate dehydrogenase (Gap) functions, analogous to S-glutathionylation, as both a redox-regulatory device and in thiol protection under oxidative stress. Critical Issues: Although the functions of the bacilliredoxin (Brx) pathways in the reversal of S-bacillithiolations have been recently addressed, significantly more work is needed to establish the complete Brx reduction pathway, including the major enzyme(s), for reduction of oxidized BSH (BSSB) and the targets of Brx action in vivo. Future Directions: Despite the large number of identified S-bacillithiolated proteins, the physiological relevance of this redox modification was shown for only selected targets and should be a subject of future studies. In addition, many more BSH-dependent detoxification enzymes are evident from previous studies, although their roles and biochemical mechanisms require further study. This review of BSH research also pin-points these missing gaps for future research. Antioxid. Redox Signal. 28, 445–462

The aldehyde dehydrogenase AldA contributes to the hypochlorite defense and is redox-controlled by protein S-bacillithiolation in Staphylococcus aureus

Staphylococcus aureus produces bacillithiol (BSH) as major low molecular weight (LMW) thiol which functions in thiol-protection and redox-regulation by protein S-bacillithiolation under hypochlorite stress. The aldehyde dehydrogenase AldA was identified as S-bacillithiolated at its active site Cys279 under NaOCl stress in S. aureus. Here, we have studied the expression, function, redox regulation and structural changes of AldA of S. aureus. Transcription of aldA was previously shown to be regulated by the alternative sigma factor SigmaB. Northern blot analysis revealed SigmaB-independent induction of aldA transcription under formaldehyde, methylglyoxal, diamide and NaOCl stress. Deletion of aldA resulted in a NaOCl-sensitive phenotype in survival assays, suggesting an important role of AldA in the NaOCl stress defense. Purified AldA showed broad substrate specificity for oxidation of several aldehydes, including formaldehyde, methylglyoxal, acetaldehyde and glycol aldehyde. Thus, AldA could be involved in detoxification of aldehyde substrates that are elevated under NaOCl stress. Kinetic activity assays revealed that AldA is irreversibly inhibited under H2O2 treatment in vitro due to overoxidation of Cys279 in the absence of BSH. Pre-treatment of AldA with BSH prior to H2O2 exposure resulted in reversible AldA inactivation due to S-bacillithiolation as revealed by activity assays and BSH-specific Western blot analysis. Using molecular docking and molecular dynamic simulation, we further show that BSH occupies two different positions in the AldA active site depending on the AldA activation state. In conclusion, we show here that AldA is an important target for S-bacillithiolation in S. aureus that is up-regulated under NaOCl stress and functions in protection under hypochlorite stress

Assessment of web crippling design provisions for application to proprietary soldier beams

Structures used for temporary works are lightweight so that they are easy to transport, erect and dismantle. Particular care should be taken in their design as local instabilities could arise due to their thin-walled nature. This article presents 12 tests on proprietary soldier beams subjected to two concentrate opposing loads applied simultaneously. The geometry of the proprietary beams feature cold-formed C-shaped sections with web holes connected back to back with internal spacers. In the absence of design rules for application to such members, the experimental results are used in the present investigation to assess the suitability of the provisions for the web crippling design of coldformed steel members as well as existing design methods from the literature, which account for the effect of perforations in the web. Experimental and predicted resistances are compared and design recommendations are provided.Leada Acro

6S RNA regulation of relA alters ppGpp levels in early stationary phase

6S RNA is a small, non-coding RNA that interacts directly with σ70-RNA polymerase and regulates transcription at many σ70-dependent promoters. Here, we demonstrate that 6S RNA regulates transcription of relA, which encodes a ppGpp synthase. The 6S RNA-dependent regulation of relA expression results in increased ppGpp levels during early stationary phase in cells lacking 6S RNA. These changes in ppGpp levels, although modest, are sufficient to result in altered regulation of transcription from σ70-dependent promoters sensitive to ppGpp, including those promoting expression of genes involved in amino acid biosynthesis and rRNA. These data place 6S RNA as another player in maintaining appropriate gene expression as cells transition into stationary phase. Independent of this ppGpp-mediated 6S RNA-dependent regulation, we also demonstrate that in later stationary phase, 6S RNA continues to downregulate transcription in general, and specifically at a subset of the amino acid promoters, but through a mechanism that is independent of ppGpp and which we hypothesize is through direct regulation. In addition, 6S RNA-dependent regulation of σS activity is not mediated through observed changes in ppGpp levels. We suggest a role for 6S RNA in modulating transcription of several global regulators directly, including relA, to downregulate expression of key pathways in response to changing environmental conditions

A theoretical and experimental study of the bowstring arch

Imperial Users onl

Innovative bridge deck with reduced reinforcement and strain -hardening fiber -reinforced cementitious composites.

Since corrosion of steel reinforcements in concrete is a major factor in the deterioration of bridge decks, this research proposes a new bridge deck system in which the top reinforcement is totally eliminated and instead, a strain-hardening fiber reinforced cement composite (or HPFRCC) is used. With the HPFRC matrix, the restraining resistance provided by the fibers, acts isotropically, thus temperature and shrinkage reinforcements are not needed. Also, the fibers help reduce crack widths, therefore minimizing ingress of corrosive agents. The bottom reinforcement is kept continuous and placed far away from the surface of the deck to prevent contact with penetrating corrosive agents, if any. This research deals with verifying the possibility of implementing this new system in real bridges. It comprises both experimental and analytical investigations. The first phase of the experimental work consists of testing the mechanical properties of HPFRC composites in order to better understand their behavior. The results obtained are used for modeling the proposed bridge deck system. The second phase of the experimental program includes the testing of thirteen two-span continuous beams simulating slab slices of bridge decks to evaluate their behavior. Parameters investigated included three types of fibers (Spectra, Torex, PVA), three types of reinforcements (steel bars, prestressing strands, CFRP), and two design concepts (reinforced concrete, prestressed concrete). The analytical work focused mainly on predicting the overall response of the proposed deck system with the combined use of nonlinear section analysis and nonlinear member analysis. Based on the findings, the proposed deck system works as anticipated. Indeed, with strain-hardening matrices, a plastic hinge mechanism formed under increasing load, leading to a response better than that of conventional reinforced concrete decks, even though the top reinforcement was eliminated, also, the proposed deck system showed higher inelastic stiffness, higher energy absorption, and higher ductility. Fibers in the HPFRC matrices help improve deck serviceability; under maximum service load, smaller permanent deflection and rotation as well as smaller crack width were observed in comparison to conventional reinforced concrete deck. Design recommendations are provided and conclusions are finally drawn.Ph.D.Applied SciencesCivil engineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/123557/2/3096067.pd

Review of Past Research on Scaffold Systems (No. R905)

This article presents an overview Of scaffold research and current practice in the design Of scaffold systems. It covers brief description Of scaffold systems including types Of joints and materials currently used. Also, types Of analysis, loads, initial geometric imperfections, and modelling Of complex joints are described. The prediction Of the ultimate load Of scaffold systems derived from simplified equations and their failure modes are shown. In addition, the article explains the design of scaffold systems based on British and Australian standards as well as how effective lengths and bracings commonly apply. The recommendations are provided for modelling, analysis and design Of scaffold systems