Acylsulfonamide safety-catch linker : promise and limitations for solid-phase oligosaccharide synthesis

Safety-catch linkers are useful for solid-phase oligosaccharide synthesis as they are orthogonal to many common protective groups. A new acylsulfonamide safety-catch linker was designed, synthesized and employed during glycosylations using an automated carbohydrate synthesizer. The analysis of the cleavage products revealed shortcomings for oligosaccharide synthesis

Aktivität, Populationsdynamik und Diversität Methan oxidierender Bakterien im Reisfeld

Die Methan oxidierenden Bakterien können durch die Umsetzung von Methan die Emission dieses Treibhausgases aus gefluteten Reisfeldern deutlich verringern. Um nähere Erkenntnisse über die Aktivität und Populationsstruktur der Methanotrophen im Reisfeld zu erhalten, wurden Mikrokosmos- und Feldexperimente durchgeführt. Die Ergebnisse dieser beiden Systeme waren qualitativ gut vergleichbar. Der positive Einfluss der Reiswurzel auf die Methanotrophen war durch die Kompartimentierung im Mikrokosmos deutlicher nachzuweisen als im Feld. Die in­situ Methanoxidation hatte sowohl im Feld als auch im Mikrokosmos nur während der ersten Wochen der Vegetationsperiode Einfluss auf die Methanemissionen. Dagegen blieben die Initialraten in Messungen der potentiellen Methanoxidation in Bodensuspensionen auch nach Abnahme der Aktivität in-situ anhaltend hoch. Dies wies auf eine in-situ Limitierung der Methan oxidierenden Bakterien hin, die auf einen Mangel an leichtverfügbaren Stickstoffverbindungen zurückgeführt werden konnte. Die Zellzahl der Methanotrophen nahm während des Wachstums der Reispflanze besonders in Rhizoplane und Homogenisat der Wurzel, aber auch im durchwurzelten Boden zu. Im Mikrokosmos konnte eine in-situ Dominanz der Typ II Methanotrophen in allen Kompartimenten und über die gesamte Vegetationsperiode nachgewiesen werden. Die Zahl der Typ I Methanotrophen erreichte nur in der Rhizoplane Anteile von bis zu 2/3 der Gesamtpopulation. Die Wurzel ist demnach nicht nur für den Erhalt der Grösse, sondern auch der Diversität der Population wichtig. Im Feldversuch wurden beide Familien in vergleichbaren Zellzahlen nachgewiesen. Die Populationsstruktur wies trotz des Wachstums der Methanotrophen keine ausgeprägten Änderungen auf. Für Typ II wurden beide Gattungen (Methylosinus und Methylocystis) nachgewiesen, während für Typ I nur zur Gattung Methylo-bacter ähnliche Sequenzen gefunden wurden. Die Dominanz von Methylobacter könnte auf einen Selektionsvorteil gegenüber anderen Typ I Gattungen zurück-zuführen sein. Da Reisfelder periodisch trocken gelegt werden, erhalten diejenigen Bodenbakterien einen Vorteil, die Trocknungsstress überstehen können. Methylo-bacter ist die einzige Typ I Gattung mit einem trocknungsresistenten Dauersta-dium und auch beide nachgewiesenen Typ II Gattungen bilden entsprechende Dauerstadien. Diese Fähigkeit ermöglichte es ihnen, im Reisfeld zu überdauern und verdeutlichte so die selektiven Auswirkungen der Physiologie auf die Populationsstruktur der Methan oxidierenden Bakterien

Ineffective off-label use of recombinant activated factor VII in a case of bone-marrow transplantation-related gastrointestinal bleeding

BACKGROUND: For patients with a normal coagulation system, who experience serious bleeding, sound evidence for recombinant activated factor VII (rFVIIa) as an effective haemostatic agent is only scarcely available so far from controlled clinical trials. In systematic reviews on the clinical use of rFVIIa, treatment failures were only rarely reported. CASE PRESENTATION: We present a 45-year old, Caucasian male with persistent intestinal bleeding due to enterocolitis associated with cytomegalovirus infection and acute graft-versus-host-disease. He had received allogeneic peripheral blood stem cell transplantation from an unrelated HLA-identical donor because of chronic myelogenous leukaemia diagnosed two years earlier. Bleeding started at day 18 after transplantation with bloody diarrhea, which was treated with multiple transfusions of fresh frozen plasma, platelet, and red blood cell concentrates, and continued relentlessly, despite all efforts, including continued transfusions, high-dose prednisolone, broad antibiotic and antiviral coverage, and tranexamic acid. Recombinant FVIIa was started at boluses of 90–120 μg/kg every 4–8 hours. Despite more than 10 doses, recurrent severe bleeding progressed to refractory shock, multiorgan failure and death. CONCLUSIONS: Little can be concluded from single case reports of clinical improvement, because publication bias in favour of positive effects is likely. Our case suggests that rFVIIa is not a panacea, in particular for severe bleeding after bone-marrow transplantation. As long as rigorous, controlled studies or comprehensive registries are lacking, conventional interventions remain the standard of care in non-haemophilic patients with severe bleeding

ERTS-1 applications to Minnesota land use mapping

Land use class definitions that can be operationally employed with ERTS-1 imagery are being developed with the cooperation of personnel from several state, regional, and federal agencies with land management responsibilities within the state and the University of Minnesota. Investigations of urban, extractive, forest, and wetlands areas indicate that it is feasible to subdivide each of these classes into several sub-classes with the use of ERTS-1 images from one or more time periods

Discovering neutrinoless double-beta decay in the era of precision neutrino cosmology

We evaluate the discovery probability of a combined analysis of proposed neutrinoless double-beta decay experiments in a scenario with normal ordered neutrino masses. The discovery probability strongly depends on the value of the lightest neutrino mass, ranging from zero in case of vanishing masses and up to 80-90% for values just below the current constraints. We study the discovery probability in different scenarios, focusing on the exciting prospect in which cosmological surveys will measure the sum of neutrino masses. Uncertainties in nuclear matrix element calculations partially compensate each other when data from different isotopes are available. Although a discovery is not granted, the theoretical motivations for these searches and the presence of scenarios with high-discovery probability strongly motivates the proposed international, multi-isotope experimental program

Sonoluminescing air bubbles rectify argon

The dynamics of single bubble sonoluminescence (SBSL) strongly depends on the percentage of inert gas within the bubble. We propose a theory for this dependence, based on a combination of principles from sonochemistry and hydrodynamic stability. The nitrogen and oxygen dissociation and subsequent reaction to water soluble gases implies that strongly forced air bubbles eventually consist of pure argon. Thus it is the partial argon (or any other inert gas) pressure which is relevant for stability. The theory provides quantitative explanations for many aspects of SBSL.Comment: 4 page

Theta-Vacuum of the Bosonized Massive Light-Front Schwinger Model

The massive Schwinger model in bosonic representation is quantized on the light front using the Dirac--Bergmann method. The non-perturbative theta- vacuum in terms of coherent states of the gauge-field zero mode is derived and found to coincide with the massless case. On the other hand, the mass term becomes highly non-linear due to the constrained zero mode of the scalar field. A non-trivial mixing between the normal-mode and zero-mode sectors of the model is crucial for the correct calculation of the theta-dependence of the leading order mass correction to the chiral condensate.Comment: 9 pages, LaTe

Towards Solving QCD in Light-Cone Quantization -- On the Spectrum of the Transverse Zero Modes for SU(2)

The formalism for a non-abelian pure gauge theory in (2+1) dimensions has recently been derived within Discretized Light-Cone Quantization, restricting to the lowest {\it transverse} momentum gluons. It is argued why this model can be a paradigm for full QCD. The physical vacuum becomes non-trivial even in light-cone quantization. The approach is brought here to tractable form by suppressing by hand both the dynamical gauge and the constraint zero mode, and by performing a Tamm-Dancoff type Fock-space truncation. Within that model the Hamiltonian is diagonalized numerically, yielding mass spectra and wavefunctions of the glue-ball states. We find that only color singlets have a stable and discrete bound state spectrum. The connection with confinement is discussed. The structure function of the gluons has a shape like $[{x(1-x)}] ^{1\over 3}$. The existence of the continuum limit is verified by deriving a coupled set of integral equations.Comment: 1 Latex file & 9 Postscript files; tarred, compressed and uuencode

Novel Approaches Reveal that \u3cem\u3eToxoplasma gondii\u3c/em\u3e Bradyzoites within Tissue Cysts Are Dynamic and Replicating Entities \u3cem\u3eIn Vivo\u3c/em\u3e

Despite their critical role in chronic toxoplasmosis, the biology of Toxoplasma gondii bradyzoites is poorly understood. In an attempt to address this gap, we optimized approaches to purify tissue cysts and analyzed the replicative potential of bradyzoites within these cysts. In order to quantify individual bradyzoites within tissue cysts, we have developed imaging software, BradyCount 1.0, that allows the rapid establishment of bradyzoite burdens within imaged optical sections of purified tissue cysts. While in general larger tissue cysts contain more bradyzoites, their relative occupancy was typically lower than that of smaller cysts, resulting in a lower packing density. The packing density permits a direct measure of how bradyzoites develop within cysts, allowing for comparisons across progression of the chronic phase. In order to capture bradyzoite endodyogeny, we exploited the differential intensity of TgIMC3, an inner membrane complex protein that intensely labels newly formed/forming daughters within bradyzoites and decays over time in the absence of further division. To our surprise, we were able to capture not only sporadic and asynchronous division but also synchronous replication of all bradyzoites within mature tissue cysts. Furthermore, the time-dependent decay of TgIMC3 intensity was exploited to gain insights into the temporal patterns of bradyzoite replication in vivo. Despite the fact that bradyzoites are considered replicatively dormant, we find evidence for cyclical, episodic bradyzoite growth within tissue cysts in vivo. These findings directly challenge the prevailing notion of bradyzoites as dormant nonreplicative entities in chronic toxoplasmosis and have implications on our understanding of this enigmatic and clinically important life cycle stage. IMPORTANCE: The protozoan Toxoplasma gondii establishes a lifelong chronic infection mediated by the bradyzoite form of the parasite within tissue cysts. Technical challenges have limited even the most basic studies on bradyzoites and the tissue cysts in vivo. Bradyzoites, which are viewed as dormant, poorly replicating or nonreplicating entities, were found to be surprisingly active, exhibiting not only the capacity for growth but also previously unrecognized patterns of replication that point to their being considerably more dynamic than previously imagined. These newly revealed properties force us to reexamine the most basic questions regarding bradyzoite biology and the progression of the chronic phase of toxoplasmosis. By developing new tools and approaches to study the chronic phase at the level of bradyzoites, we expose new avenues to tackle both drug development and a better understanding of events that may lead to reactivated symptomatic disease