Type Three Secretion System-Dependent Microvascular Thrombosis and Ischemic Enteritis in Human Gut Xenografts Infected with Enteropathogenic Escherichia coli

Enteropathogenic Escherichia coli (EPEC) is a leading cause of severe intestinal disease and infant mortality in developing countries. Virulence is mediated by a type three secretion system (T3SS), causing the hallmark attaching and effacing (AE) lesions and actin-rich pedestal formation beneath the infecting bacteria on the apical surface of enterocytes. EPEC is a human-specific pathogen whose pathogenesis cannot be studied in animal models. We therefore established an EPEC infection model in human gut xenografts in SCID mice and used it to study the role of T3SS in the pathogenesis of the disease. Following EPEC O127: H6 strain E2348/69 infection, T3SS-dependent AE lesions and pedestals were demonstrated in all infected xenografts. We report here the development of T3SS-dependent intestinal thrombotic microangiopathy (iTMA) and ischemic enteritis in similar to 50% of infected human gut xenografts. Using species-specific CD31 immunostaining, we showed that iTMA was limited to the larger human-mouse chimeric blood vessels, which are located between the muscularis mucosa and circular muscular layer of the human gut. These blood vessels were massively invaded by bacteria, which adhered to and formed pedestals on endothelial cells and aggregated with mouse neutrophils in the lumen. We conclude that endothelial infection, iTMA, and ischemic enteritis might be central mechanisms underlying severe EPEC-mediated disease

A Characterization of Scale Invariant Responses in Enzymatic Networks

An ubiquitous property of biological sensory systems is adaptation: a step increase in stimulus triggers an initial change in a biochemical or physiological response, followed by a more gradual relaxation toward a basal, pre-stimulus level. Adaptation helps maintain essential variables within acceptable bounds and allows organisms to readjust themselves to an optimum and non-saturating sensitivity range when faced with a prolonged change in their environment. Recently, it was shown theoretically and experimentally that many adapting systems, both at the organism and single-cell level, enjoy a remarkable additional feature: scale invariance, meaning that the initial, transient behavior remains (approximately) the same even when the background signal level is scaled. In this work, we set out to investigate under what conditions a broadly used model of biochemical enzymatic networks will exhibit scale-invariant behavior. An exhaustive computational study led us to discover a new property of surprising simplicity and generality, uniform linearizations with fast output (ULFO), whose validity we show is both necessary and sufficient for scale invariance of enzymatic networks. Based on this study, we go on to develop a mathematical explanation of how ULFO results in scale invariance. Our work provides a surprisingly consistent, simple, and general framework for understanding this phenomenon, and results in concrete experimental predictions

Serum amyloid A (SAA): a novel biomarker for uterine serous papillary cancer

BACKGROUND: Uterine serous papillary carcinoma (USPC) is a biologically aggressive variant of endometrial cancer. We investigated the expression of Serum Amyloid A (SAA) and evaluated its potential as a serum biomarker in USPC patients. METHODS: SAA gene and protein expression levels were evaluated in USPC and normal endometrial tissues (NEC) by real-time PCR, immunohistochemistry (IHC), flow cytometry and by a sensitive bead-based immunoassay. SAA concentration in 123 serum samples from 51 healthy women, 42 women with benign diseases, and 30 USPC patients were also studied. RESULTS: SAA gene expression levels were significantly higher in USPC when compared with NEC (mean copy number by RT\u2013PCR\ubc162 vs 2.21; P\ubc0.0002). IHC revealed diffuse cytoplasmic SAA protein staining in USPC tissues. High intracellular levels of SAA were identified in primary USPC cell lines evaluated by flow cytometry and SAA was found to be actively secreted in vitro. SAA concentrations (mgml 1) had a median (95% CIs) of 6.0 (4.0\u20138.9) in normal healthy females and 6.0 (4.2\u20138.1) in patients with benign disease (P\ubc0.92). In contrast, SAA values in the serum of USPC patients had a median (95% CI) of 15.6 (9.2\u201356.2), significantly higher than those in the healthy group (P\ubc0.0005) and benign group (P\ubc0.0006). Receiver operating characteristics (ROC) analysis of serum SAA to classify advanced- and early-stage USPC yielded an area under the ROC curve of 0.837 (P\ubc0.0024). CONCLUSION: SAA is not only a liver-secreted protein but is also a USPC cell product. SAA may represent a novel biomarker for USPC to assist in staging patients preoperatively, and to monitor early-disease recurrence and response to therapy

Study of cosolvent-induced α-chymotrypsin fibrillogenesis: Does protein surface hydrophobicity trigger early stages of aggregation reaction?

The misfolding of specific proteins is often associated with their assembly into fibrillar aggregates, commonly termed amyloid fibrils. Despite the many efforts expended to characterize amyloid formation in vitro, there is no deep knowledge about the environment (in which aggregation occurs) as well as mechanism of this type of protein aggregation. Alpha-chymotrypsin was recently driven toward amyloid aggregation by the addition of intermediate concentrations of trifluoroethanol. In the present study, approaches such as turbidimetric, thermodynamic, intrinsic fluorescence and quenching studies as well as chemical modification have been successfully used to elucidate the underlying role of hydrophobic interactions (involved in early stages of amyloid formation) in α-chymotrypsin-based experimental system. © 2009 Springer Science+Business Media, LLC

Tourism Destination Management: A Collaborative Approach

Collaboration is a key factor of sustainable growth across territories and industrial sectors. Tourism, one of the largest industries in the world, has been subject to strongest innovation in the last years. Main reasons of this reside both in the availability of new ICTs - Information and Communication Technologies - and organizational models, which directly connect tourists among them and with service providers, and in the always more personalized supply of tourism experience. Tourism destinations can benefit of such innovations if they are able to reorganize the territorial tourism offer around different pattern of collaboration in order to give 2.0 tourists opportunities to live an augmented tourism experience. This paper deals with the possible forms of collaborative networks that can rise within a destination with a focus on relationships between services delivered by the Tourism Destination and the requests of services at the different phases of the tourist 2.0 lifecycle

Performance of a multianalyte test as an aid for the diagnosis of ovarian cancer in symptomatic women

Background: Concomitant with the development of in vitro diagnostic multivariate index assays (IVDMIAs) to improve the diagnostic efficiency of ovarian cancer detection is the need to identify appropriate biostatistical approaches to assess improvements in risk predication. In this study, we assessed the utility of three different approaches for comparing diagnostic efficiency of an ovarian cancer multivariate assay in a retrospective case control phase 2 biomarker trial. The control cohort included both disease-free women and women with benign gynecological conditions to more accurately reflect the target population of symptomatic women

Differential Gene Expression Regulated by Oscillatory Transcription Factors

Cells respond to changes in the internal and external environment by a complex regulatory system whose end-point is the activation of transcription factors controlling the expression of a pool of ad-hoc genes. Recent experiments have shown that certain stimuli may trigger oscillations in the concentration of transcription factors such as NF-B and p53 influencing the final outcome of the genetic response. In this study we investigate the role of oscillations in the case of three different well known gene regulatory mechanisms using mathematical models based on ordinary differential equations and numerical simulations. We considered the cases of direct regulation, two-step regulation and feed-forward loops, and characterized their response to oscillatory input signals both analytically and numerically. We show that in the case of indirect two-step regulation the expression of genes can be turned on or off in a frequency dependent manner, and that feed-forward loops are also able to selectively respond to the temporal profile of oscillating transcription factors