Functional Implication of Dp71 in Osmoregulation and Vascular Permeability of the Retina

Functional alterations of Müller cells, the principal glia of the retina, are an early hallmark of most retina diseases and contribute to their further progression. The molecular mechanisms of these reactive Müller cell alterations, resulting in disturbed retinal homeostasis, remain largely unknown. Here we show that experimental detachment of mouse retina induces mislocation of the inwardly rectifying potassium channels (Kir4.1) and a downregulation of the water channel protein (AQP4) in Müller cells. These alterations are associated with a strong decrease of Dp71, a cytoskeleton protein responsible for the localization and the clustering of Kir4.1 and AQP4. Partial (in detached retinas) or total depletion of Dp71 in Müller cells (in Dp71-null mice) impairs the capability of volume regulation of Müller cells under osmotic stress. The abnormal swelling of Müller cells In Dp71-null mice involves the action of inflammatory mediators. Moreover, we investigated whether the alterations in Müller cells of Dp71-null mice may interfere with their regulatory effect on the blood-retina barrier. In the absence of Dp71, the retinal vascular permeability was increased as compared to the controls. Our results reveal that Dp71 is crucially implicated in the maintenance of potassium homeostasis, in transmembraneous water transport, and in the Müller cell-mediated regulation of retinal vascular permeability. Furthermore, our data provide novel insights into the mechanisms of retinal homeostasis provided by Müller cells under normal and pathological conditions

Learning to live together: mutualism between self-splicing introns and their hosts

Group I and II introns can be considered as molecular parasites that interrupt protein-coding and structural RNA genes in all domains of life. They function as self-splicing ribozymes and thereby limit the phenotypic costs associated with disruption of a host gene while they act as mobile DNA elements to promote their spread within and between genomes. Once considered purely selfish DNA elements, they now seem, in the light of recent work on the molecular mechanisms regulating bacterial and phage group I and II intron dynamics, to show evidence of co-evolution with their hosts. These previously underappreciated relationships serve the co-evolving entities particularly well in times of environmental stress

A Novel Method to Verify Multilevel Computational Models of Biological Systems Using Multiscale Spatio-Temporal Meta Model Checking

Insights gained from multilevel computational models of biological systems can be translated into real-life applications only if the model correctness has been verified first. One of the most frequently employed in silico techniques for computational model verification is model checking. Traditional model checking approaches only consider the evolution of numeric values, such as concentrations, over time and are appropriate for computational models of small scale systems (e.g. intracellular networks). However for gaining a systems level understanding of how biological organisms function it is essential to consider more complex large scale biological systems (e.g. organs). Verifying computational models of such systems requires capturing both how numeric values and properties of (emergent) spatial structures (e.g. area of multicellular population) change over time and across multiple levels of organization, which are not considered by existing model checking approaches. To address this limitation we have developed a novel approximate probabilistic multiscale spatio-temporal meta model checking methodology for verifying multilevel computational models relative to specifications describing the desired/expected system behaviour. The methodology is generic and supports computational models encoded using various high-level modelling formalisms because it is defined relative to time series data and not the models used to generate it. In addition, the methodology can be automatically adapted to case study specific types of spatial structures and properties using the spatio-temporal meta model checking concept. To automate the computational model verification process we have implemented the model checking approach in the software tool Mule (http://mule.modelchecking.org). Its applicability is illustrated against four systems biology computational models previously published in the literature encoding the rat cardiovascular system dynamics, the uterine contractions of labour, the Xenopus laevis cell cycle and the acute inflammation of the gut and lung. Our methodology and software will enable computational biologists to efficiently develop reliable multilevel computational models of biological systems

Corticotropin-Releasing Factor (CRF) Sensitization of Ethanol Withdrawal-Induced Anxiety-Like Behavior is Brain Site Specific and Mediated by CRF-1 Receptors: Relation to Stress-Induced SensitizationS⃞

In abstinent alcoholics, stress induces negative affect—a response linked to craving and relapse. In rats, repeated stresses at weekly intervals before 5-day ethanol diet sensitize withdrawal-induced anxiety-like behavior (“anxiety”) that is blocked by a corticotrophin-releasing factor 1 (CRF-1)-receptor antagonist. Current experiments were performed to identify brain sites that support CRF involvement in stress sensitization of ethanol withdrawal-induced anxiety-like behavior. First, different doses of CRF microinjected weekly into the central amygdala (CeA) before ethanol exposure produced a dose-related sensitization of anxiety during ethanol withdrawal. Subsequently, CRF microinjection into the basolateral amygdala, dorsal raphe nucleus (DRN), or dorsal bed nucleus of the stria terminalis (d-BNST) also sensitized ethanol withdrawal-induced anxiety. In contrast, sensitization of ethanol withdrawal-induced anxiety was not observed after weekly CRF administration into the ventral-BNST, CA1-hippocampal region, or hypothalamic-paraventricular nucleus. Then, experiments documented the CRF receptor subtype responsible for CRF and stress sensitization of withdrawal-induced anxiety. Systemic administration of a CRF-1 receptor antagonist before CRF microinjection into the CeA, DRN, or d-BNST prevented CRF-induced sensitization of anxiety during ethanol withdrawal. Furthermore, repeated microinjections of urocortin-3, a CRF-2 receptor agonist, into the CRF-positive sites did not sensitize anxiety after withdrawal from ethanol. Finally, microinjection of a CRF-1 receptor antagonist into the CeA, DRN, or d-BNST before stress blocked sensitization of anxiety-like behavior induced by the repeated stress/ethanol withdrawal protocol. These results indicate that CRF released by stress acts on CRF-1 receptors within specific brain regions to produce a cumulative adaptation that sensitizes anxiety-like behavior during withdrawal from chronic ethanol exposure

Cancer-Related Symptom Clusters, Eosinophils, and Survival in Hepatobiliary Cancer: An Exploratory Study

CONTEXT: The study of symptom clusters is gaining increased attention in the field of oncology in an attempt to improve the quality of life of patients diagnosed with cancer. OBJECTIVES: The aims of the present study were to: (1) determine the prevalence and distribution of pain, fatigue, and symptoms of depression and their covariation as a cluster in people with hepatobiliary carcinoma; (2) characterize how variation in each individual symptom and/or their covariation as a cluster are associated with changes in immunity; and (3) determine if the symptom clusters, and associated biomarkers, are related to survival in people diagnosed with hepatobiliary carcinoma. METHODS: Two hundred and six participants diagnosed with hepatobiliary carcinoma completed a battery of standardized questionnaire measuring cancer-related symptoms. Peripheral blood leukocytes were measured at diagnosis, three- and six-month follow-ups. Survival was measured from the date of diagnosis to death. RESULTS: Cancer-related symptoms were prevalent and two-step hierarchical cluster analyses yielded three clusters. High levels of pain, fatigue, and depression were found to be associated with elevated eosinophil percentages (F[1,78]=3.1, P=0.05) at three-month and six-month follow-ups using repeated measures ANOVA. Using multivariate latent growth curve modeling, pain was the primary symptom associated with elevated eosinophil percentages between diagnosis and six months (z=2.24, P=0.05). Using Cox regression, vascular invasion and age were negatively associated with survival (Chi-square=21.6, P=0.03). While stratifying for vascular invasion, Kaplan Meier survival analysis was performed and eosinophil levels above the median for the sample were found to be related to increased survival in patients with and without vascular invasion (Breslow Chi-square=4.9, P=0.03). Symptom clusters did not mediate the relationship between eosinophils and survival. CONCLUSION: Cancer-related symptoms, particularly pain and depression, were associated with increased percentages of eosinophils. The presence of symptoms may reflect tumor cell death and be indicative of response to treatment, or other processes, in patients with hepatobiliary carcinoma