Catabolite regulation of the cytochrome c550-encoding Bacillus subtilis cccA gene

In Gram-positive bacteria, catabolite control protein A (CcpA)-mediated catabolite repression or activation regulates not only the expression of a great number of catabolic operons, but also the synthesis of enzymes of central metabolic pathways. We found that a constituent of the Bacillus subtilis respiratory chain, the small cytochrome c550 encoded by the cccA gene, was also submitted to catabolite repression. Similar to most catabolite-repressed genes and operons, the Bacillus subtilis cccA gene contains a potential catabolite response element cre, an operator site recognized by CcpA. The presumed cre overlaps the -35 region of the cccA promoter. Strains carrying a cccA'-IacZ fusion formed blue colonies when grown on rich solid medium, whereas white colonies were obtained when glucose was present. beta-Galactosidase assays with cells grown in rich medium confirmed the repressive effect of glucose on cccA'-lacZ expression. Introduction of a ccpA or hprK mutation or of a mutation affecting the presumed cccA cre relieved the repressive effect of glucose during late log phase. An additional glucose repression mechanism was activated during stationary phase, which was not relieved by the ccpA, hprK or cre mutations. An interaction of the repressor/corepressor complex (CcpA/seryl-phosphorylated HPr (P-Ser-HPr)) with the cccA cre could be demonstrated by gel shift experiments. By contrast, a DNA fragment carrying mutations in the presumed cccA cre was barely shifted by the CcpA/P-Ser-HPr complex. In footprinting experiments, the region corresponding to the presumed cccA cre was specifically protected in the presence of the CcpA/P-Ser-HPr complex.     

Effect of heterochiral inversions on the structure of a β-hairpin peptide

We study computationally a family of β-hairpin peptides with systematically introduced chiral inversions, in explicit water, and we investigate the extent to which the backbone structure is able to fold in the presence of heterochiral perturbations. In contrast to the recently investigated case of a helical peptide, we do not find a monotonic change in secondary structure content as a function of the number of L- to D-inversions. The effects of L- to D-inversions are instead found to be highly position-specific. Additionally, in contrast to the helical peptide, some inversions increase the stability of the folded peptide: in such cases, we compute an increase in β-sheet content in the aqueous solution equilibrium ensemble. However, the tertiary structures of the stable (folded) configurations for peptides for which inversions cause an increase in β-sheet content show differences from one another, as well as from the native fold of the nonchirally perturbed β-hairpin. Our results suggest that although some chiral perturbations can increase folding stability, chirally perturbed proteins may still underperform functionally, given the relationship between structure and function.     

Breast cancer stromal elastosis is associated with mammography screening detection,low Ki67 expression and favourable prognosis in a population-based study

Squamous cell carcinomas (SCCs) are uncommon, high-grade tumors, predominantly composed of round cells in the prepuce. The aim of this study is to better define the clinicopathologic features of this neoplasm. We conducted cyto-histopathologic analysis on the manifestations of the prepuce SCC by H &; E staining in a terrier mix dog. Grossly, tumor was large, multiple erythematous patch, and ulcerated masses frequently affecting the prepuce and deeply invading to distal prepuce out from the ventro-lateral of penis and the tumor covered by a necrotic discharge. Cytological evaluation of fine-needle aspirates from the cutaneous mass from the prepuce comprised of round nuclei, coarse chromatin pattern, distinct nucleoli and nuclear pleomorphism. Furthermore, the neoplastic cells were pleomorphic, round to caudate in shape, exhibiting prominent anisokaryosis and anisocytosis with rare mitotic features. Microscopically, the lesions were predominantly composed of atypical round cells disposed in interlacing fascicles. Frequent findings include keratin formation, horn pearls, mitoses and cellular atypia. The cells showed distinct borders, ranged from polygonal to round or elongate and had moderate amounts of eosinophilic cytoplasm. The histopathologic features coupled with the cytopathology findings led to a diagnosis of squamous cell carcinoma. To the authors’ knowledge, this is the first time that multiple erythematous plaques have undergone malignant transformation in a terrier mix dog. The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/5748771971272873     

Preoperative Diffusion-Weighted Imaging of Single Brain Metastases Correlates with Patient Survival Times

Background

MRI-based diffusion-weighted imaging (DWI) visualizes the local differences in water diffusion in vivo. The prognostic value of DWI signal intensities on the source images and apparent diffusion coefficient (ADC) maps respectively has not yet been studied in brain metastases (BM).

Methods

We included into this retrospective analysis all patients operated for single BM at our institution between 2002 and 2010, in whom presurgical DWI and BM tissue samples were available. We recorded relevant clinical data, assessed DWI signal intensity and apparent diffusion coefficient (ADC) values and performed histopathological analysis of BM tissues. Statistical analyses including uni- and multivariate survival analyses were performed.

Results

65 patients (34 female, 31 male) with a median overall survival time (OS) of 15 months (range 0–99 months) were available for this study. 19 (29.2%) patients presented with hyper-, 3 (4.6%) with iso-, and 43 (66.2%) with hypointense DWI. ADCmean values could be determined in 32 (49.2%) patients, ranged from 456.4 to 1691.8*10⁻⁶ mm²/s (median 969.5) and showed a highly significant correlation with DWI signal intensity. DWI hyperintensity correlated significantly with high amount of interstitial reticulin deposition. In univariate analysis, patients with hyperintense DWI (5 months) and low ADCmean values (7 months) had significantly worse OS than patients with iso/hypointense DWI (16 months) and high ADCmean values (30 months), respectively. In multivariate survival analysis, high ADCmean values retained independent statistical significance.

Conclusions

Preoperative DWI findings strongly and independently correlate with OS in patients operated for single BM and are related to interstitial fibrosis. Inclusion of DWI parameters into established risk stratification scores for BM patients should be considered.     

Hand preferences on unimanual and bimanual tasks in Tonkean macaques (Macaca tonkeana)

This is the first study to examine hand preferences in Tonkean macaques on a bimanual task. One of our objectives was to continue the move toward greater task standardization, in order to facilitate comparisons between species and studies on handedness. The main aim was to test and determine task robustness, by varying intra‐task complexity. To this end, we administered several different tasks to the subjects: two unimanual tasks (grasping task featuring items of different sizes) and three coordinated bimanual tasks (tube task involving different materials, weights, and diameters). Although we found no significant hand preference in either task at the group level, the macaques were more strongly lateralized for small items than for large ones in the unimanual grasping task. Moreover, the absence of a correlation between these two versions of the unimanual task confirmed the weakness of this grasping task for assessing handedness. Regarding the bimanual tube task, no difference was found between the three versions in either the direction or the strength of hand preference. Moreover, the highly correlated hand preferences between these three versions suggest that the tube task provides a more robust means of measuring manual preferences. Am J Phys Anthropol 152:315–321, 2013. © 2013 Wiley Periodicals, Inc.     

Ezrin/Radixin/Moesin Are Required for the Purinergic P2X7 Receptor (P2X7R)-dependent Processing of the Amyloid Precursor Protein

The amyloid precursor protein (APP) can be cleaved by α-secretases in neural cells to produce the soluble APP ectodomain (sAPPα), which is neuroprotective. We have shown previously that activation of the purinergic P2X7 receptor (P2X7R) triggers sAPPα shedding from neural cells. Here, we demonstrate that the activation of ezrin, radixin, and moesin (ERM) proteins is required for the P2X7R-dependent proteolytic processing of APP leading to sAPPα release. Indeed, the down-regulation of ERM by siRNA blocked the P2X7R-dependent shedding of sAPPα. We also show that P2X7R stimulation triggered the phosphorylation of ERM. Thus, ezrin translocates to the plasma membrane to interact with P2X7R. Using specific pharmacological inhibitors, we established the order in which several enzymes trigger the P2X7R-dependent release of sAPPα. Thus, a Rho kinase and the MAPK modules ERK1/2 and JNK act upstream of ERM, whereas a PI3K activity is triggered downstream. For the first time, this work identifies ERM as major partners in the regulated non-amyloidogenic processing of APP.