40 research outputs found
Bank resolution and safeguarding the creditors left behind
Not for the first time, the global banking crisis illustrated the vulnerability of banks to a loss of confidence by their depositors, other creditors and counterparties. The experience highlighted the need to have special arrangements for dealing with failing banks - ‘special resolution regime’ — that provides the authorities with the tools necessary to reduce the systemic risks arising from a bank’s failure while at the same time limiting the taxpayers’ exposure to the costs. The United Kingdom’s own Special Resolution Regime for dealing with failing banks and building societies was born out of the difficulties in dealing with the failure of Northern Rock in the autumn of 2007.
Inferring median survival differences in general factorial designs via permutation tests
Factorial survival designs with right-censored observations are commonly
inferred by Cox regression and explained by means of hazard ratios. However, in
case of non-proportional hazards, their interpretation can become cumbersome;
especially for clinicians. We therefore offer an alternative: median survival
times are used to estimate treatment and interaction effects and null
hypotheses are formulated in contrasts of their population versions.
Permutation-based tests and confidence regions are proposed and shown to be
asymptotically valid. Their type-1 error control and power behavior are
investigated in extensive simulations, showing the new methods' wide
applicability. The latter is complemented by an illustrative data analysis
RMST-based multiple contrast tests in general factorial designs
Several methods in survival analysis are based on the proportional hazards
assumption. However, this assumption is very restrictive and often not
justifiable in practice. Therefore, effect estimands that do not rely on the
proportional hazards assumption are highly desirable in practical applications.
One popular example for this is the restricted mean survival time (RMST). It is
defined as the area under the survival curve up to a prespecified time point
and, thus, summarizes the survival curve into a meaningful estimand. For
two-sample comparisons based on the RMST, previous research found the inflation
of the type I error of the asymptotic test for small samples and, therefore, a
two-sample permutation test has already been developed. The first goal of the
present paper is to further extend the permutation test for general factorial
designs and general contrast hypotheses by considering a Wald-type test
statistic and its asymptotic behavior. Additionally, a groupwise bootstrap
approach is considered. Moreover, when a global test detects a significant
difference by comparing the RMSTs of more than two groups, it is of interest
which specific RMST differences cause the result. However, global tests do not
provide this information. Therefore, multiple tests for the RMST are developed
in a second step to infer several null hypotheses simultaneously. Hereby, the
asymptotically exact dependence structure between the local test statistics is
incorporated to gain more power. Finally, the small sample performance of the
proposed global and multiple testing procedures is analyzed in simulations and
illustrated in a real data example
Epidemiologic Relationship between Toscana Virus Infection and Leishmania infantum Due to Common Exposure to Phlebotomus perniciosus Sandfly Vector
Sand flies are recognised vectors of parasites in the genus Leishmania and a number of arthropod-borne viruses, in particular viruses within the genus Phlebovirus, family Bunyaviridae. In southern France, Toscana phlebovirus (TOSV) is recognized as a prominent cause of summer meningitis. Since Leishmania and TOSV have a common vector (Phlebotomus perniciosus), an epidemiologic link has been assumed for a long time. However, there is no scientific evidence of such a link between human leishmaniosis and phleboviral infections. To identify a possible link, we investigated the presence and distribution of antibodies against these two microorganisms (i) in individuals and (ii) at a spatial level in the city of Marseille (south-eastern France). Five hundred sera were selected randomly in the biobank of the Department of Parasitology of the Public Hospitals of Marseille. All sera were previously tested for IgG against Leishmania by Western Blotting, and TOSV IgG were detected by indirect immunofluorescence. The seropositivity rates were 21.4% for TOSV and 28% for Leishmania. Statistical analysis demonstrated that seropositivity for one pathogen was significantly associated with seropositivity to the other pathogen. This result provided the first robust evidence for the existence of an epidemiological relationship between Leishmania infantum and TOSV. Addresses of tested patients were geolocalized and integrated into Geographical Information System software, in order to test spatial relationship between the two pathogens. Spatial analysis did not allow to identify (i) specific patterns for the spatial distribution of positive serological results for TOSV or Leishmania, and (ii) a spatial relationship between Leishmania and TOSV positive serological results. This may reflect the fact that the sample studied was not powerful enough to demonstrate either a spatial clustering or co-location, i.e. that the actual risk exposure area is smaller than the mean of distance between patients in our study (245 m)
Tubulin Binds to the Cytoplasmic Loop of TRESK Background K+ Channel In Vitro.
The cytoplasmic loop between the second and third transmembrane segments is pivotal in the regulation of TRESK (TWIK-related spinal cord K+ channel, K2P18.1, KCNK18). Calcineurin binds to this region and activates the channel by dephosphorylation in response to the calcium signal. Phosphorylation-dependent anchorage of 14-3-3 adaptor protein also modulates TRESK at this location. In the present study, we identified molecular interacting partners of the intracellular loop. By an affinity chromatography approach using the cytoplasmic loop as bait, we have verified the specific association of calcineurin and 14-3-3 to the channel. In addition to these known interacting proteins, we observed substantial binding of tubulin to the intracellular loop. Successive truncation of the polypeptide and pull-down experiments from mouse brain cytosol narrowed down the region sufficient for the binding of tubulin to a 16 amino acid sequence: LVLGRLSYSIISNLDE. The first six residues of this sequence are similar to the previously reported tubulin-binding region of P2X2 purinergic receptor. The tubulin-binding site of TRESK is located close to the protein kinase A (PKA)-dependent 14-3-3-docking motif of the channel. We provide experimental evidence suggesting that 14-3-3 competes with tubulin for the binding to the cytoplasmic loop of TRESK. It is intriguing that the 16 amino acid tubulin-binding sequence includes the serines, which were previously shown to be phosphorylated by microtubule-affinity regulating kinases (MARK kinases) and contribute to channel inhibition. Although tubulin binds to TRESK in vitro, it remains to be established whether the two proteins also interact in the living cell