Proteasomal degradation of cytotoxic necrotizing factor 1-activated rac

The cytotoxic necrotizing factor 1 (CNF1) from Escherichia coli has been shown to activate members of the Rho family by deamidation of glutamine 63. This amino acid is essential for hydrolysis of GTP, and any substitution results in a constitutively active Rho. Activation of Rho induces the formation of stress fibers, filopodia, and membrane ruffles due to activation of RhoA, Cdc42, and Rac, respectively. Here we show that the level of endogenous Rac decreased in CNF1-treated HEK293 and HeLa cells. The amount of mRNA remained unaffected, leaving the possibility that Rac is subject to proteolytic degradation. Treatment of cells with lactacystin, an inhibitor of the 26S proteasome, protected Rac from degradation. We have previously shown that CNF1 activates the c-Jun N-terminal kinase (JNK) only transiently in HeLa cells (M. Lerm, J. Selzer, A. Hoffmeyer, U. R. Rapp, K. Aktories, and G. Schmidt, Infect. Immun. 67:496-503, 1998). Here we show that CNF1-induced JNK activation is stabilized in the presence of lactacystin. The data indicate that Rac is degraded by a proteasome-dependent pathway in CNF1-treated cells.     

Activation of RhoA,B,C by Yersinia Cytotoxic Necrotizing Factor (CNFy) Induces Apoptosis in LNCaP Prostate Cancer Cells

Prostate cancer is the most common malignancy, accounting for about 25% of all incident cases among men in industrialized countries. The human androgen-dependent prostate cancer cell line LNCaP, which is derived from a metastatic lesion of human prostatic adenocarcinoma, is frequently used to study prostate cancer associated signaling pathways in vitro. Recently it was described that Rho GTPase activation in these cells leads to apoptotic responses. We used the bacterial toxins CNFy and CNF1, which specifically and directly activate Rho GTPases by deamidation of a single glutamine. We asked whether these Rho activators could induce apoptosis in LNCaP cells. Our results indicate that RhoA activation, induced by CNFy, does lead to intrinsic apoptosis of the cells. Analysis of the underlying signaling pathway reveals that apoptosis induction requires the activity of Rho kinase (ROCK) and myosin activation, an apoptotic pathway previously identified in cancer stem cells.     

Are faecal markers good indicators of mucosal healing in inflammatory bowel disease?

AIM: To review the published literature concerning the accuracy of faecal inflammatory markers for identifying mucosal healing. METHODS: Bibliographical searches were performed in MEDLINE electronic database up to February 2015,using the following terms: "inflammatory bowel disease","Crohn′s disease","ulcerative colitis","faecal markers","calprotectin","lactoferrin","S100A12","endoscop*","mucosal healing","remission". In addition,relevant references from these studies were also included. Data were extracted from the published papers including odds ratios with 95%CI,P values and correlation coefficients. Data were grouped together according to each faecal marker,Crohn's disease or ulcerative colitis,and paediatric compared with adult study populations. Studies included in this review assessed mucosal inflammation by endoscopic and/or histological means and compared these findings to faecal marker concentrations in inflammatory bowel diseases(IBD) patient cohorts. Articles had to be published between 1990 and February 2015 and written in English. Papers excluded from the review were those where the faecal biomarker concentration was compared between patients with IBD and controls or other disease groups,those where serum biomarkers were used,those with a heterogeneous study population and those only assessing post-operative disease. RESULTS: The available studies show that faecal markers,such as calprotectin and lactoferrin,are promising non-invasive indicators of mucosal healing. However,due to wide variability in study design,especially with regard to the definition of mucosal healing and evaluation of marker cut offs,the available data do not yet indicate the optimal roles of these markers. Thirty-six studies published between 1990 and 2014 were included. Studies comprised variable numbers of study participants,considered CD(15-164 participants) or UC(12-152 participants) separately or as a combined group(11-252 participants). Eight reports included paediatric patients. Several indices were used to document mucosal inflammation,encompassing elevenendoscopic and eight histologic grading systems. The majority of the available reports focused on faecal calprotectin(33 studies),whilst others assessed faecal lactoferrin(13 studies) and one study assessed S100A12. Across all of the biomarkers,there is a wide range of correlation describing the association between faecal markers and endoscopic disease activity(r values ranging from 0.32 to 0.87,P values ranging from 0.0001 to 0.7815). Correlation coefficients are described in almost all studies and are used more commonly than outcome measures such as sensitivity,specificity,PPV and/or NPV. Overall,the studies that have evaluated faecal calprotectin and/or faecal lactoferrin and their relationship with endoscopic disease activity show inconsistent results. CONCLUSION: Future studies should report the results of faecal inflammatory markers in the context of mucosal healing with clear validated cut offs.     

Economic impact of community-acquired and nosocomial lower respiratory tract infections in young children in Germany

Data on the economic burden of lower respiratory tract infections (LRTI) in young children are lacking in Germany. The objective of the cost-of-illness study was to estimate the economic impact of community-acquired LRTI and nosocomial LRTI as well as of infections due to respiratory syncytial virus (RSV), parainfluenza viruses (PIV) and influenza viruses (IV). The economic analysis is part of the PRI.DE study, a prospective, multi-centre, population-based epidemiological study on the impact of LRTI in children aged 0 to 36 months in Germany. The analysis includes children with community-acquired infections (1329 cases treated as outpatients, 2039 cases treated as inpatients) and nosocomial infections (90 cases). Medical services consumed were generated by chart abstraction and parental expenses data by telephone interviews within four weeks after physician visit or hospitalisation. Costs were evaluated from following perspectives: third party payer, parent and society. Total costs for outpatient treatment are €123 per LRTI case. Stratified by virus type, total costs per case are €163 (RSV), €100 (PIV) and €223 (IV). Total costs per hospitalised LRTI case amount to €2579. Stratified by virus type, total costs per case are €2772 (RSV), €2374 (PIV) and €2597 (IV). Total costs per nosocomial case are €2814. Economic burden due to LRTI is €213 million annually. It is concluded that treatment of LRTI in children up to age three causes a considerable economic burden in Germany. Presented results are the first data describing the economic burden of LRTI in young children assessed by means of the incidence data for Germany. This cost-of-illness study provides basic data for further decision-making, focusing on the economic assessment of preventive strategies for RSV, PIV and IV infections.     

Prospective population-based study of viral lower respiratory tract infections in children under 3 years of age (the PRI.DE study)

Population-based incidence data from Europe on the disease burden of lower respiratory tract infections (LRTI) due to respiratory syncytial viruses (RSV), parainfluenza viruses (PIV) and influenzaviruses (IV) are lacking, especially with respect to the disease burden. In a 2-year prospective multicentre study of children aged <3 years in Germany, we registered population-based cases as outpatients (n=2386), inpatients (n=2924), and nosocomially-acquired (n=141). Nasopharyngeal secretions were tested for viral RNA. The annual incidence for physician visits per 100 children for all LRTI was 28.7, RSV 7.7, PIV 3.8 and IV 1.1. Annual hospitalisation rates per 10⁵ children were for all LRTI 2941, RSV 1117, PIV 261 and IV 123. Annual nosocomial cases per 10⁵ hospital days were for all LRTI 79, RSV 29, PIV 9 and IV 1.5. All five children (0.27%) who died had an underlying disease and four were nosocomially acquired. Conclusion: Hospitalisation rates due to lower respiratory tract infections in healthy children were similar to those reported elsewhere; the rates for outpatient visits were approximately ten times higher.     

Indications for predismissal testing with arrhythmia-induction in patients receiving an implantable cardioverter defibrillator

Arrhythmia induction during implantation of cardioverter defibrillators (ICD) is a standard procedure. However, controversy exists regarding the need for routine arrhythmia induction before discharge from hospital (pre-hospital discharge (PHD) test). In order to reduce the number of tests we identified risk factors that predict relevant ICD malfunction. METHODS AND RESULTS: 965 patients receiving a first device implantation (n=724) or device/system replacement (n=241) between 1998 and 2004 were analysed. During implantation 176 (18%) complications (intraoperative undersensing of induced arrhythmias, unsuccessful arrhythmia-therapy or low DFT safety margin) occurred. Frequent (>4 times) intraoperative lead repositioning due to low sensing values was present in 44 patients (5%). 9% of the patients with first ICD implantation, 21% with device replacement and 27% with system replacement developed complications during PHD testing with arrhythmia induction. Intraoperative complications, although corrected during implantation, were independent risk factors for malfunction during PHD testing (p<0.05). Additional predictors for malfunction were intraoperative lead repositioning (>4 times) and a history of both VF and VT (p<0.05). Patients without intraoperative complications rarely developed malfunction during PHD testing (3.7% first device, 6.25% system replacement). Only in patients undergoing device replacement was a higher risk for failure (13%) evident. No risk factors could be identified for these subgroups. CONCLUSION: Routine arrhythmia induction during PHD is recommended in ICD patients with intraoperative complications, although corrected during implantation, as well as frequent intraoperatives lead repositioning. Patients undergoing device/system replacement uncomplicated implantation are not generally at low risk for device failure.     

Tenascin C and tenascin R similarly prevent the formation of myelin membranes in a RhoA‐dependent manner,but antagonistically regulate the expression of myelin basic protein via a separate pathway

Membrane formation and the initiation of myelin gene expression are hallmarks of the differentiation of oligodendrocytes from their precursors. Here, we compared the roles of the two related extracellular matrix (ECM) glycoproteins Tenascin C (Tnc) and Tenascin R (Tnr) in oligodendrocyte differentiation. Oligodendrocyte precursors from Tnr‐deficient mice exhibited reduced differentiation, as revealed by retarded expression of myelin basic protein (MBP) in culture. This could be rescued with purified Tnr. In contrast, when we cultured oligodendrocytes on a Tnc‐containing, astrocyte‐derived ECM, they barely expressed MBP. This inhibition could be overcome when we used ECM from astrocytes deficient for Tnc, suggesting that Tnc inhibits differentiation. In contrast to their antagonistic effect on differentiation, both Tnc and Tnr similarly inhibited morphologic maturation. When oligodendrocytes were cultured on the purified glycoproteins, process elaboration and membrane expansion were reduced. Both Tnc and Tnr interfered with the activation of the small GTPase RhoA. Conversely, RhoA and Rac1 activation induced by cytotoxic necrotizing factor 1 (CNF1) increased the formation of myelin membranes, whereas Y27632‐mediated inhibition of the Rho‐cascade prevented it without, however, affecting the fraction of MBP‐expressing cells. Because Tnc and Tnr play antagonistic roles for differentiation and comparably inhibit morphologic maturation, we conclude that independent molecular pathways regulate these processes. © 2009 Wiley‐Liss, Inc.     

Verbal coding and visual memory in aphasics

Fluent and non-fluent aphasics, non-aphasic brain-damaged patients, schizophrenics, and normal controls were tested in a non-verbal visual retention task (object-drawings, snowflakes). All groups of neurological and psychiatric patients scored lower than normal controls under a rehearsal condition. Differences levelled off when a distractor task was interpolated. While fluent aphasics were impaired with both the object-drawings and the snowflakes, non-fluent aphasics were impaired only with the latter. Results are discussed with respect to the verbal-encoding hypothesis and other theories of aphasia.     

Cytotoxic Necrotizing Factors (CNFs)-A Growing Toxin Family

The Escherichia coli Cytotoxic Necrotizing Factors, CNF1, CNF2, CNF3 and CNFY from Yersinia pseudotuberculosis belong to a family of deamidating toxins. CNFs deamidate glutamine 63/61 in the switch II region of Rho GTPases that is essential for GTP hydrolysing activity. Deamidation leads to constitutive activation of Rho GTPases. However, cellular mechanisms like proteasomal degradation of the activated Rho proteins restrict the action of the GTPases. This review describes the differences between the toxin family members concerning expression, cellular entry and substrate specificity.