94 research outputs found
Integration of Static and Dynamic Analysis Techniques for Checking Noninterference
In this article, we present an overview of recent combinations of deductive program verification and automatic test generation on the one hand and static analysis on the other hand, with the goal of checking noninterference. Noninterference is the non-functional property that certain confidential information cannot leak to certain public output, i.e., the confidentiality of that information is always preserved.
We define the noninterference properties that are checked along with the individual approaches that we use in different combinations. In one use case, our framework for checking noninterference employs deductive verification to automatically generate tests for noninterference violations with an improved test coverage. In another use case, the framework provides two combinations of deductive verification with static analysis based on system dependence graphs to prove noninterference, thereby reducing the effort for deductive verification
Vitamin D-tour : cognition and depression: the role of vitamin D and its interplay with glucose homeostasis
According to recent estimations approximately 35.6 million people have dementia worldwide. Globally, 350 million people experience one or more depressive episodes during their life. As the therapeutic options for dementia and depression are limited, these conditions form a major challenge for public health and society. More and more researchers have initiated research on potential preventive factors for dementia and depression, including the potential effects of nutritional factors. The aim of this PhD-thesis was to study the role of vitamin D and its potential interplay with glucose homeostasis, in the development of cognitive decline and depression, using epidemiological data as well experimental animal data. Chapter 2 recapitulates a debate between vitamin D experts that was organized to make a step towards the harmonization on the formulation of optimal vitamin D intake levels and serum 25(OH)D concentrations across Europe. It was concluded that based on the current evidence-base 25(OH)D concentrations ≥50 nmol/L are sufficient with respect to optimal bone health. For health outcomes beyond bone health evidence was considered insufficient to formulate optimal levels. In order to achieve and maintain a 25(OH)D concentration ≥50 nmol/L, older adults aged ≥65 years were recommended to adhere to a vitamin D intake of 20 μg/day. Chapter 3 shows that there is a high prevalence of 25(OH)D inadequacy in a population of Dutch older adults that participated in the B-PROOF study (n=2857), namely 45% had 25(OH)D concentrations In chapter 4 the associations between 25(OH)D status and global cognitive performance (n=116), depressive symptoms (n=118), and surrogate markers of glucose intolerance (n=593) were evaluated using data of European adults aged 70-75 years. None of the associations reached significance. Studying the potential role of vitamin D in domain-specific cognitive performance and depression in 127 Dutch pre-frail and frail older adults aged ≥65 years (chapter 5), showed an association between 25(OH)D concentration and executive functioning, and a tendency towards an association with information processing speed. Stratification for ‘low’ and ‘high’ fasting glucose concentrations did not suggest an interaction between vitamin D and glucose homeostasis in the association with domain-specific cognitive performance. Moreover, adding fasting glucose or insulin did not substantially influence the associations between 25(OH)D status and domain-specific cognitive performance, and hence a mediation effect of glucose homeostasis was considered unlikely. We furthermore observed associations of 25(OH)D status with attention and working memory (n=787) (chapter 6), depression (n=2839) (chapter 7) and grey matter volume of the brain (n=217) (chapter 8) in a population community-dwelling Dutch older adults aged ≥65 years. Again, these studies did not provide evidence that the associations were modified or mediated by glucose intolerance. However, it should be emphasized that glucose intolerance in these three chapters was defined sub-optimally, specifically using blood samples that may have been collected in a non-fasting state, or by using self-reported diabetes data. Hence, the mediation and interaction effects should be interpreted cautiously. Finally, chapter 9 shows the results of a proof of principle study on the effect of a long-term vitamin D deficiency on cognitive decline and emotional reactivity in old C57BL/6j mice. Modest tendencies were shown for a relation between vitamin D and spatial learning, but these tendencies did not reach significance. Vitamin D deficiency did not affect recognition memory, spatial memory or emotional reactivity. Mice that received a higher dietary fat load, which was given to induce an impaired glucose tolerance, did not respond differently to a vitamin D deficiency than mice that received a low fat diet did. Overall, it is concluded that the evidence for an effect of vitamin D on cognitive performance/decline, depression or brain volume is insufficient to formulate disease specific cut-off values for vitamin D intake or 25(OH)D status. However, given the high prevalence of 25(OH)D concentrations <50 nmol/L we do call for a more active promotion of the current vitamin D intake recommendations.</p
Reproductive performance in sows in relation to Japanese Encephalitis Virus seropositivity in an endemic area
Japanese Encephalitis Virus (JEV) is considered an important reproductive pathogen in pigs. Most studies of the reproductive impact of JEV have been conducted in areas where the disease occurs in seasonal epidemics. In this study, the associations between seropositivity for JEV, measured with an IgG ELISA, and the number of piglets born alive and stillborn were investigated in a tropical area endemic for JEV in Vietnam. Sixty percent of sows from four farms in the Mekong delta of Vietnam were seropositive to JEV and the Odds Ratio for a sow being infected was highest (6.4) in sows above 3.5 years (95% confidence interval 2.2–18.3). There was an association between increasing Optical Density (OD) values from the ELISA and the number of stillborn piglets in sows less than 1.5 years, but no effect of seropositivity could be shown when all sows were studied. OD values had an effect (p = 0.04) on the number of piglets born alive in the statistical analysis only when interacting with the effect of the breeds. An increase in mean OD value of the herd was correlated (p < 0.0001) with an increase in the number of piglets born alive. In this study, there was evidence of a negative association between seropositivity for JEV and the reproductive performance only in sows less than 1.5 years in endemic areas. This could be explained by a year-round infection with the virus, which would lead to immunity in many gilts before their first pregnancy. This, in turn, may imply that JEV infection in pigs is of minor importance for the reproductive performance in endemic areas
A conscious mouse model of gastric ileus using clinically relevant endpoints
BACKGROUND: Gastric ileus is an unsolved clinical problem and current treatment is limited to supportive measures. Models of ileus using anesthetized animals, muscle strips or isolated smooth muscle cells do not adequately reproduce the clinical situation. Thus, previous studies using these techniques have not led to a clear understanding of the pathophysiology of ileus. The feasibility of using food intake and fecal output as simple, clinically relevant endpoints for monitoring ileus in a conscious mouse model was evaluated by assessing the severity and time course of various insults known to cause ileus. METHODS: Delayed food intake and fecal output associated with ileus was monitored after intraperitoneal injection of endotoxin, laparotomy with bowel manipulation, thermal injury or cerulein induced acute pancreatitis. The correlation of decreased food intake after endotoxin injection with gastric ileus was validated by measuring gastric emptying. The effect of endotoxin on general activity level and feeding behavior was also determined. Small bowel transit was measured using a phenol red marker. RESULTS: Each insult resulted in a transient and comparable decrease in food intake and fecal output consistent with the clinical picture of ileus. The endpoints were highly sensitive to small changes in low doses of endotoxin, the extent of bowel manipulation, and cerulein dose. The delay in food intake directly correlated with delayed gastric emptying. Changes in general activity and feeding behavior were insufficient to explain decreased food intake. Intestinal transit remained unchanged at the times measured. CONCLUSION: Food intake and fecal output are sensitive markers of gastric dysfunction in four experimental models of ileus. In the mouse, delayed gastric emptying appears to be the major cause of the anorexic effect associated with ileus. Gastric dysfunction is more important than small bowel dysfunction in this model. Recovery of stomach function appears to be simultaneous to colonic recovery
Gastrodin Inhibits Allodynia and Hyperalgesia in Painful Diabetic Neuropathy Rats by Decreasing Excitability of Nociceptive Primary Sensory Neurons
Painful diabetic neuropathy (PDN) is a common complication of diabetes mellitus and adversely affects the patients’ quality of life. Evidence has accumulated that PDN is associated with hyperexcitability of peripheral nociceptive primary sensory neurons. However, the precise cellular mechanism underlying PDN remains elusive. This may result in the lacking of effective therapies for the treatment of PDN. The phenolic glucoside, gastrodin, which is a main constituent of the Chinese herbal medicine Gastrodia elata Blume, has been widely used as an anticonvulsant, sedative, and analgesic since ancient times. However, the cellular mechanisms underlying its analgesic actions are not well understood. By utilizing a combination of behavioral surveys and electrophysiological recordings, the present study investigated the role of gastrodin in an experimental rat model of STZ-induced PDN and to further explore the underlying cellular mechanisms. Intraperitoneal administration of gastrodin effectively attenuated both the mechanical allodynia and thermal hyperalgesia induced by STZ injection. Whole-cell patch clamp recordings were obtained from nociceptive, capsaicin-sensitive small diameter neurons of the intact dorsal root ganglion (DRG). Recordings from diabetic rats revealed that the abnormal hyperexcitability of neurons was greatly abolished by application of GAS. To determine which currents were involved in the antinociceptive action of gastrodin, we examined the effects of gastrodin on transient sodium currents (INaT) and potassium currents in diabetic small DRG neurons. Diabetes caused a prominent enhancement of INaT and a decrease of potassium currents, especially slowly inactivating potassium currents (IAS); these effects were completely reversed by GAS in a dose-dependent manner. Furthermore, changes in activation and inactivation kinetics of INaT and total potassium current as well as IAS currents induced by STZ were normalized by GAS. This study provides a clear cellular basis for the peripheral analgesic action of gastrodin for the treatment of chronic pain, including PDN
Hyperpolarization-Activated Current (Ih) in Ganglion-Cell Photoreceptors
Intrinsically photosensitive retinal ganglion cells (ipRGCs) express the photopigment melanopsin and serve as the primary retinal drivers of non-image-forming visual functions such as circadian photoentrainment, the pupillary light reflex, and suppression of melatonin production in the pineal. Past electrophysiological studies of these cells have focused on their intrinsic photosensitivity and synaptic inputs. Much less is known about their voltage-gated channels and how these might shape their output to non-image-forming visual centers. Here, we show that rat ipRGCs retrolabeled from the suprachiasmatic nucleus (SCN) express a hyperpolarization-activated inwardly-rectifying current (Ih). This current is blocked by the known Ih blockers ZD7288 and extracellular cesium. As in other systems, including other retinal ganglion cells, Ih in ipRGCs is characterized by slow kinetics and a slightly greater permeability for K+ than for Na+. Unlike in other systems, however, Ih in ipRGCs apparently does not actively contribute to resting membrane potential. We also explore non-specific effects of the common Ih blocker ZD7288 on rebound depolarization and evoked spiking and discuss possible functional roles of Ih in non-image-forming vision. This study is the first to characterize Ih in a well-defined population of retinal ganglion cells, namely SCN-projecting ipRGCs
High prevalence of antibiotic resistance in commensal Escherichia coli among children in rural Vietnam
Acquisition and Evolution of Plant Pathogenesis–Associated Gene Clusters and Candidate Determinants of Tissue-Specificity in Xanthomonas
is a large genus of plant-associated and plant-pathogenic bacteria. Collectively, members cause diseases on over 392 plant species. Individually, they exhibit marked host- and tissue-specificity. The determinants of this specificity are unknown. lineage. genome and indicate that differentiation with respect to host- and tissue-specificity involved not major modifications or wholesale exchange of clusters, but subtle changes in a small number of genes or in non-coding sequences, and/or differences outside the clusters, potentially among regulatory targets or secretory substrates
Pan-cancer analysis of whole genomes
Cancer is driven by genetic change, and the advent of massively parallel sequencing has enabled systematic documentation of this variation at the whole-genome scale(1-3). Here we report the integrative analysis of 2,658 whole-cancer genomes and their matching normal tissues across 38 tumour types from the Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium of the International Cancer Genome Consortium (ICGC) and The Cancer Genome Atlas (TCGA). We describe the generation of the PCAWG resource, facilitated by international data sharing using compute clouds. On average, cancer genomes contained 4-5 driver mutations when combining coding and non-coding genomic elements; however, in around 5% of cases no drivers were identified, suggesting that cancer driver discovery is not yet complete. Chromothripsis, in which many clustered structural variants arise in a single catastrophic event, is frequently an early event in tumour evolution; in acral melanoma, for example, these events precede most somatic point mutations and affect several cancer-associated genes simultaneously. Cancers with abnormal telomere maintenance often originate from tissues with low replicative activity and show several mechanisms of preventing telomere attrition to critical levels. Common and rare germline variants affect patterns of somatic mutation, including point mutations, structural variants and somatic retrotransposition. A collection of papers from the PCAWG Consortium describes non-coding mutations that drive cancer beyond those in the TERT promoter(4); identifies new signatures of mutational processes that cause base substitutions, small insertions and deletions and structural variation(5,6); analyses timings and patterns of tumour evolution(7); describes the diverse transcriptional consequences of somatic mutation on splicing, expression levels, fusion genes and promoter activity(8,9); and evaluates a range of more-specialized features of cancer genomes(8,10-18).Peer reviewe
Measurement of the Ratio of b Quark Production Cross Sections in Antiproton-Proton Collisions at 630 GeV and 1800 GeV
We report a measurement of the ratio of the bottom quark production cross
section in antiproton-proton collisions at 630 GeV to 1800 GeV using bottom
quarks with transverse momenta greater than 10.75 GeV identified through their
semileptonic decays and long lifetimes. The measured ratio
sigma(630)/sigma(1800) = 0.171 +/- .024 +/- .012 is in good agreement with
next-to-leading order (NLO) quantum chromodynamics (QCD)
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