DEVELOPMENTAL AND CELLULAR FUNCTIONS OF DELTA-CATENIN

Catenins have diverse and powerful roles in embryogenesis, homeostasis or disease progression, as best exemplified by the well-known beta-catenin. The less studied delta-catenin likewise contains a central Armadillo-domain. In common with other p120 sub-class members, it acts in a variety of intracellular compartments and modulates cadherin stability, small GTPase activities and gene transcription. In mammals, delta-catenin exhibits neural specific expression, with its knock-out in mice correspondingly producing cognitive defects and synaptic dysfunctions. My work instead employed the amphibian, Xenopus laevis, to explore delta-catenin’s physiological functions in a distinct vertebrate system. Initial isolation and characterization indicated delta-catenin’s expression in Xenopus. Unlike the pattern observed for mammals, delta-catenin was detected in most adult Xenopus tissues, although enriched in embryonic structures of neural fate as visualized using RNA in-situ hybridization. To determine delta-catenin’s requirement in amphibian development, I employed anti-sense morpholinos to knock-down gene products, finding that delta-catenin depletion results in developmental defects in gastrulation, neural crest migration and kidney tubulogenesis, phenotypes that were specific based upon rescue experiments. In biochemical and cellular assays, delta-catenin knock-down reduced cadherin levels and cell adhesion, and impaired activation of RhoA and Rac1, small GTPases that regulate actin dynamics and morphogenetic movements. Indeed, exogenous C-cadherin, or dominant-negative RhoA or dominant-active Rac1, significantly rescued delta-catenin depletion. Thus, my results indicate delta-catenin’s essential roles in Xenopus development, with contributing functional links to cadherins and Rho family small G proteins. In examining delta-catenin’s nuclear roles, I identified delta-catenin as an interacting partner and substrate of the caspase-3 protease, which plays critical roles in apoptotic as well as non-apoptotic processes. Delta-catenin’s interaction with and sensitivity to caspase-3 was confirmed using assays involving its cleavage in vitro, as well as within Xenopus apoptotic extracts or mammalian cell lines. The cleavage site, a highly conserved caspase consensus motif (DELD) within Armadillo-repeat 6 of delta-catenin, was identified through peptide sequencing. Cleavage thus generates an amino- (1-816) and carboxyl-terminal (817-1314) fragment each containing about half of the central Armadillo-domain. I found that cleavage of delta-catenin both abolishes its association with cadherins, and impairs its ability to modulate small GTPases. Interestingly, the carboxyl-terminal fragment (817-1314) possesses a conserved putative nuclear localization signal that I found is needed to facilitate delta-catenin’s nuclear targeting. To probe for novel nuclear roles of delta-catenin, I performed yeast two-hybrid screening of a mouse brain cDNA library, resolving and then validating its interaction with an uncharacterized KRAB family zinc finger protein I named ZIFCAT. My results indicate that ZIFCAT is nuclear, and suggest that it may associate with DNA as a transcriptional repressor. I further determined that other p120 sub-class catenins are similarly cleaved by caspase-3, and likewise bind ZIFCAT. These findings potentially reveal a simple yet novel signaling pathway based upon caspase-3 cleavage of p120 sub-family members, facilitating the coordinate modulation of cadherins, small GTPases and nuclear functions. Together, my work suggested delta-catenin’s essential roles in Xenopus development, and has revealed its novel contributions to cell junctions (via cadherins), cytoskeleton (via small G proteins), and nucleus (via ZIFCAT). Future questions include the larger role and gene targets of delta-catenin in nucleus, and identification of upstream signaling events controlling delta-catenin’s activities in development or disease progression.

Molecular evolution of primate immunodeficiency viruses and hepatitis delta virus

Primate immunodeficiency viruses, or lentiviruses (HIV-1, HIV-2, and SIV), and hepatitis delta virus (HDV) are RNA viruses characterized by rapid evolution. Infection by primate immunodeficiency viruses usually results in the development of acquired immunodeficiency syndrome (AIDS) in humans and AIDS-like illnesses in Asian macaques. Similarly, hepatitis delta virus infection causes hepatitis and liver cancer in humans. These viruses are heterogeneous within an infected patient and among individuals. Substitution rates in the virus genomes are high and vary in different lineages and among sites. Methods of phylogenetic analysis were applied to study the evolution of primate lentiviruses and the hepatitis delta virus. The following results have been obtained: (1) The substitution rate varies among sites of primate lentivirus genes according to the two parameter gamma distribution, with the shape parameter $\alpha$ being close to 1. (2) Primate immunodeficiency viruses fall into species-specific lineages. Therefore, viral transmissions across primate species are not as frequent as suggested by previous authors. (3) Primate lentiviruses have acquired or lost their pathogenicity several times in the course of evolution. (4) Evidence was provided for multiple infections of a North American patient by distinct HIV-1 strains of the B subtype. (5) Computer simulations indicate that the probability of committing an error in testing HIV transmission depends on the number of virus sequences and their length, the divergence times among sequences, and the model of nucleotide substitution. (6) For future investigations of HIV-1 transmissions, using longer virus sequences and avoiding the use of distant outgroups is recommended. (7) Hepatitis delta virus strains are usually related according to the geographic region of isolation. (8) Evolution of HDV is characterized by the rate of synonymous substitution being lower than the nonsynonymous substitution rate and the rate of evolution of the noncoding region. (9) There is a strong preference for G and C nucleotides at the third codon positions of the HDV coding region. ^

Three-dimensional Vortex Structures on Heated Micro-lattice in a Gas

This paper addresses the microscale heat transfer problem from heated lattice to the gas. A micro-device for enhanced heat transfer is presented and numerically investigated. Thermal creep induces 3-D vortex structures in the vicinity of the lattice. The gas flow is in the slip flow regime (Knudsen number Kn⩽0.1Kn⩽0.1). The simulations are performed using slip flow Navier–Stokes equations with boundary condition formulations proposed by Maxwell and Smoluchowski. In this study the wire thicknesses and distances of the heated lattice are varied. The surface geometrical properties alter significantly heat flux through the surface.

The Effects of Flowline Length Evolution on Chemistry-Delta O-18 Profiles from Penny Ice Cap, Baffin Island, Canada

The isotopic and chemical signatures for ice-age and Holocene ice from Summit, Greenland and Penny Ice Cap, Baffin Island, Canada, arc compared. The usual pattern of low delta(18)O, high Ca2+ and high Cl- is presented in the Summit records, but Penny Ice Cap has lower than present Cl- in its ice-age ice. A simple extension of the Hansson model (Hansson, 1994) is developed and used to simulate these signatures. The low ice-age Cl- from Penny Ice Cap is explained by having the ice-age ice originating many thousands of km inland near the centre of the Laurentide ice sheet and much further from the marine sources. Summit's flowlines all start close to the present site. The Penny Ice Cap early-Holocene delta(18)O's had to be corrected to offset the Laurentide meltwater distortion. The analysis suggests that presently the Summit and Penny Ice Cap marine impurity originates about,500 km away, and that presently Penny Ice Cap receives a significant amount of local continental impurity.

Combined systemic and local morpholino treatment rescues the phenotype of the SMA Delta 7 mouse model

Spinal muscular atrophy (SMA) is a childhood fatal motor neuron disease caused by mutations in the Survival Motor Neuron 1 (SMN1) gene, currently without effective treatment. One possible therapeutic approach is the use of antisense oligonucleotides (ASOs) to redirect the splicing of a paralogous gene, SMN2, to increase the production of functional SMN protein. A range of ASOs with different chemical properties is suitable for these applications, including a morpholino (MO) variant, which has a particularly excellent safety, and efficacy profile. We used a 25- nt MO oligomer sequence against the ISS-N1 region of SMN2 (HSMN2Ex7D(-10-34)) with superior efficacy to previously described sequences also in transgenic SMA Δ7 mice. The combined local and systemic administration of MO (bare or conjugated to octa-guanidine) is necessary to increase full-length SMN expression, leading to robust neuropathological features improvement and survival rescue. Additionally, several snRNA levels that are dysregulated in SMA mice could be restored by MO treatment. These results demonstrate that MO therapy is efficacious and can result in phenotypic rescue. These data provide important insights for the development of therapeutic strategies in SMA patients.

Measurement of isolated-photon pair production in pp collisions at sqrts=7 TeV with the ATLAS detector

The ATLAS experiment at the LHC has measured the production cross section of events with two isolated photons in the final state, in proton-proton collisions at root s = 7 TeV. The full data set collected in 2011, corresponding to an integrated luminosity of 4.9 fb(-1), is used. The amount of background, from hadronic jets and isolated electrons, is estimated with data-driven techniques and subtracted. The total cross section, for two isolated photons with transverse energies above 25 GeV and 22 GeV respectively, in the acceptance of the electromagnetic calorimeter (vertical bar eta vertical bar < 1.37 and 1.52 < vertical bar eta vertical bar 2.37) and with an angular separation Delta R > 0.4, is 44.0(-4.2)(+3.2) pb. The differential cross sections as a function of the di-photon invariant mass, transverse momentum, azimuthal separation, and cosine of the polar angle of the largest transverse energy photon in the Collins-Soper di-photon rest frame are also measured. The results are compared to the prediction of leading-order parton-shower and next-to-leading-order and next-to-next-to-leading-order parton-level generators.

Simultaneous quantification of delta-9-THC, THC-acid A, CBN and CBD in seized drugs using HPLC-DAD

An HPLC-DAD method for the quantitative analysis of Δ(9)-tetrahydrocannabinol (THC), Δ(9)-tetrahydrocannabinolic acid-A (THCA-A), cannabidiol (CBD), and cannabinol (CBN) in confiscated cannabis products has been developed, fully validated and applied to analyse seized cannabis products. For determination of the THC content of plant material, this method combines quantitation of THCA-A, which is the inactive precursor of THC, and free THC. Plant material was dried, homogenized and extracted with methanol by ultrasonication. Chromatographic separation was achieved with a Waters Alliance 2695 HPLC equipped with a Merck LiChrospher 60 RP-Select B (5μm) precolumn and a Merck LiChroCart 125-4 LiChrospher 60 RP-Select B (5μm) analytical column. Analytes were detected and quantified using a Waters 2996 photo diode array detector. This method has been accepted by the public authorities of Switzerland (Bundesamt für Gesundheit, Federal Office of Public Health), and has been used to analyse 9092 samples since 2000. Since no thermal decarboxylation of THCA-A occurs, the method is highly reproducible for different cannabis materials. Two calibration ranges are used, a lower one for THC, CBN and CBD, and a higher one for THCA-A, due to its dominant presence in fresh plant material. As provider of the Swiss proficiency test, the robustness of this method has been tested over several years, and homogeneity tests even in the low calibration range (1%) show high precision (RSD≤4.3%, except CBD) and accuracy (bias≤4.1%, except CBN).

The impacts of volcanic aerosol on stratospheric ozone and the Northern Hemisphere polar vortex: separating radiative-dynamical changes from direct effects due to enhanced aerosol heterogeneous chemistry

After major volcanic eruptions the enhanced aerosol causes ozone changes due to greater heterogeneous chemistry on the particle surfaces (HET-AER) and from dynamical effects related to the radiative heating of the lower stratosphere (RAD-DYN). We carry out a series of experiments with an atmosphere–ocean–chemistry–climate model to assess how these two processes change stratospheric ozone and Northern Hemispheric (NH) polar vortex dynamics. Ensemble simulations are performed under present day and preindustrial conditions, and with aerosol forcings representative of different eruption strength, to investigate changes in the response behaviour. We show that the halogen component of the HET-AER effect dominates under present-day conditions with a global reduction of ozone (−21 DU for the strongest eruption) particularly at high latitudes, whereas the HET-AER effect increases stratospheric ozone due to N2O5 hydrolysis in a preindustrial atmosphere (maximum anomalies +4 DU). The halogen-induced ozone changes in the present-day atmosphere offset part of the strengthening of the NH polar vortex during mid-winter (reduction of up to −16 m s-1 in January) and slightly amplify the dynamical changes in the polar stratosphere in late winter (+11 m s-1 in March). The RAD-DYN mechanism leads to positive column ozone anomalies which are reduced in a present-day atmosphere by amplified polar ozone depletion (maximum anomalies +12 and +18 DU for present day and preindustrial, respectively). For preindustrial conditions, the ozone response is consequently dominated by RAD-DYN processes, while under present-day conditions, HET-AER effects dominate. The dynamical response of the stratosphere is dominated by the RAD-DYN mechanism showing an intensification of the NH polar vortex in winter (up to +10 m s-1 in January). Ozone changes due to the RAD-DYN mechanism slightly reduce the response of the polar vortex after the eruption under present-day conditions.

Intravenous Delta-9-Tetrahydrocannabinol to Prevent Postoperative Nausea and Vomiting: A Randomized Controlled Trial.

BACKGROUND Evidence suggests that cannabinoids can prevent chemotherapy-induced nausea and vomiting. The use of tetrahydrocannabinol (THC) has also been suggested for the prevention of postoperative nausea and vomiting (PONV), but evidence is very limited and inconclusive. To evaluate the effectiveness of IV THC in the prevention of PONV, we performed this double-blind, randomized, placebo-controlled trial with patient stratification according to the risk of PONV. Our hypothesis was that THC would reduce the relative risk of PONV by 25% compared with placebo. METHODS With IRB approval and written informed consent, 40 patients at high risk for PONV received either 0.125 mg/kg IV THC or placebo at the end of surgery before emergence from anesthesia. The primary outcome parameter was PONV during the first 24 hours after emergence. Secondary outcome parameters included early and late nausea, emetic episodes and PONV, and side effects such as sedation or psychotropic alterations. RESULTS The relative risk reduction of overall PONV in the THC group was 12% (95% confidence interval, -37% to 43%), potentially less than the clinically significant 25% relative risk reduction demonstrated by other drugs used for PONV prophylaxis. Calculation of the effect of treatment group on overall PONV by logistic regression adjusted for anesthesia time gave an odds ratio of 0.97 (95% confidence interval, 0.21 to 4.43, P = 0.97). Psychotropic THC side effects were clinically relevant and mainly consisted of sedation and confusion that were not tampered by the effects of anesthesia. The study was discontinued after 40 patients because of the inefficacy of THC against PONV and the finding of clinically unacceptable side effects that would impede the use of THC in the studied setting. CONCLUSIONS Because of an unacceptable side effect profile and uncertain antiemetic effects, IV THC administered at the end of surgery before emergence from anesthesia cannot be recommended for the prevention of PONV in high-risk patients.