Acute Myeloblastic Leukemia and Myelodysplastic Syndrome: Azacitidine for Prophylactic and Preventive Purposes after Allogeneic Hematopoietic Stem Cell Transplantation

Aim. To evaluate the effectiveness of preventive and prophylactic post-transplantation therapy using azacitidine (5-AZA) in patients at high risk of post-transplantation relapse. Methods. 136 patients were included in the study performed by the pairwise comparison: 68 of them received 5-AZA after allo-HSCT and 68 patients were included in the historical control group. 5-AZA was prescribed for prophylactic or preventive purposes. The results were assessed according to the OS, RR, EFS, DUM, and relapse-free and GVHR-free survival. Results. 1-year OS was 76 % in the 5-AZA group (95% CI 60–84 %) and 44 % in the reference group (95% CI 33–55 %) (p = 0.001); 2-year OS was 63 % (95% CI 39–67 %) and 37 % (95% CI 26–48 %) (p = 0.007), respectively. The relapse rate (RR) in the 5-AZA group was 34 % (95% CI 22–46 %) during 1 year and 51 % (95% CI 38–64 %) in the reference group (p = 0.02). 1- and 2-year disease unrelated mortality (DUM) was similar: 5 % in the 5-AZA group (95% CI 0.1–14.0 %) and 25 % (95% CI 13–37 %) in the reference group (p = 0.005). 1-year EFS was 76 % in the 5-AZA group (95% CI 61–85 %) and 44 % in the reference group (95% CI 33–55 %) (p = 0.001); 2-year EFS was 63 % (95% CI 39–67 %) and 37 % (95% CI 26–48 %) (p = 0.01), respectively. 1-year relapse-free and GVHR-free survival was 55 % in the 5-AZA group (95% CI 41–69 %) and 28 % in the reference group (95% CI 17–39 %) (p = 0.001); 2-year relapse-free and GVHR-free survival was 47 % (95% CI 32–62 %) and 27 % (95% CI 17–37 %) (p = 0.002), respectively. Conclusion. The use of 5-AZA for prophylactic and preventive purposes after allo-HSCT does not increase the risk of GVHR and DUM, does not suppress the GVL effect and can be used in combination with the donor lymphocyte infusion (DLI). The therapy with 5-AZA is safe during the early period after allo-HSCT. The drug does not suppress the GVL effect and can be used in high risk patients to prevent early post-transplantation relapse. The use of 5-AZA in combination with DLI does not increase the incidence of severe GVHR

Light-Dependant Biostabilisation of Sediments by Stromatolite Assemblages

For the first time we have investigated the natural ecosystem engineering capacity of stromatolitic microbial assemblages. Stromatolites are laminated sedimentary structures formed by microbial activity and are considered to have dominated the shallows of the Precambrian oceans. Their fossilised remains are the most ancient unambiguous record of early life on earth. Stromatolites can therefore be considered as the first recognisable ecosystems on the planet. However, while many discussions have taken place over their structure and form, we have very little information on their functional ecology and how such assemblages persisted despite strong eternal forcing from wind and waves. The capture and binding of sediment is clearly a critical feature for the formation and persistence of stromatolite assemblages. Here, we investigated the ecosystem engineering capacity of stromatolitic microbial assemblages with respect to their ability to stabilise sediment using material from one of the few remaining living stromatolite systems (Highborne Cay, Bahamas). It was shown that the most effective assemblages could produce a rapid (12–24 h) and significant increase in sediment stability that continued in a linear fashion over the period of the experimentation (228 h). Importantly, it was also found that light was required for the assemblages to produce this stabilisation effect and that removal of assemblage into darkness could lead to a partial reversal of the stabilisation. This was attributed to the breakdown of extracellular polymeric substances under anaerobic conditions. These data were supported by microelectrode profiling of oxygen and calcium. The structure of the assemblages as they formed was visualised by low-temperature scanning electron microscopy and confocal laser microscopy. These results have implications for the understanding of early stromatolite development and highlight the potential importance of the evolution of photosynthesis in the mat forming process. The evolution of photosynthesis may have provided an important advance for the niche construction activity of microbial systems and the formation and persistence of the stromatolites which came to dominate shallow coastal environments for 80% of the biotic history of the earth

The origin of multicellularity in cyanobacteria

Background: Cyanobacteria are one of the oldest and morphologically most diverse prokaryotic phyla on our planet. The early development of an oxygen-containing atmosphere approximately 2.45 - 2.22 billion years ago is attributed to the photosynthetic activity of cyanobacteria. Furthermore, they are one of the few prokaryotic phyla where multicellularity has evolved. Understanding when and how multicellularity evolved in these ancient organisms would provide fundamental information on the early history of life and further our knowledge of complex life forms. Results: We conducted and compared phylogenetic analyses of 16S rDNA sequences from a large sample of taxa representing the morphological and genetic diversity of cyanobacteria. We reconstructed ancestral character states on 10,000 phylogenetic trees. The results suggest that the majority of extant cyanobacteria descend from multicellular ancestors. Reversals to unicellularity occurred at least 5 times. Multicellularity was established again at least once within a single-celled clade. Comparison to the fossil record supports an early origin of multicellularity, possibly as early as the “Great Oxygenation Event” that occurred 2.45 - 2.22 billion years ago. Conclusions: The results indicate that a multicellular morphotype evolved early in the cyanobacterial lineage and was regained at least once after a previous loss. Most of the morphological diversity exhibited in cyanobacteria today —including the majority of single-celled species— arose from ancient multicellular lineages. Multicellularity could have conferred a considerable advantage for exploring new niches and hence facilitated the diversification of new lineages

Space Telescope and Optical Reverberation Mapping Project. IX. Velocity–Delay Maps for Broad Emission Lines in NGC 5548

In this contribution, we achieve the primary goal of the active galactic nucleus (AGN) STORM campaign by recovering velocity–delay maps for the prominent broad emission lines (Lyα, C iv, He ii, and Hβ) in the spectrum of NGC 5548. These are the most detailed velocity–delay maps ever obtained for an AGN, providing unprecedented information on the geometry, ionization structure, and kinematics of the broad-line region. Virial envelopes enclosing the emission-line responses show that the reverberating gas is bound to the black hole. A stratified ionization structure is evident. The He ii response inside 5–10 lt-day has a broad single-peaked velocity profile. The Lyα, C iv, and Hβ responses extend from inside 2 to outside 20 lt-day, with double peaks at ±2500 km s−1 in the 10–20 lt-day delay range. An incomplete ellipse in the velocity–delay plane is evident in Hβ. We interpret the maps in terms of a Keplerian disk with a well-defined outer rim at R = 20 lt-day. The far-side response is weaker than that from the near side. The line-center delay $\tau =(R/c)(1-\sin i)\approx 5$ days gives the inclination i ≈ 45°. The inferred black hole mass is MBH ≈ 7 × 107 M⊙. In addition to reverberations, the fit residuals confirm that emission-line fluxes are depressed during the "BLR Holiday" identified in previous work. Moreover, a helical "Barber-Pole" pattern, with stripes moving from red to blue across the C iv and Lyα line profiles, suggests azimuthal structure rotating with a 2 yr period that may represent precession or orbital motion of inner-disk structures casting shadows on the emission-line region farther out

Bandwidth-Limited Picosecond Pulses from an Injection GaAlAs DH Laser with an External Dispersive Cavity

Mode locking of semiconductor lasers with external dispersive cavities is investigated both experimentally and theoretically. The external cavity consists of a microscope objective and a diffraction grating. Bandwidth-limited tunable picosecond pulses (FWHM about 3 ps and Δτ · Δυ= 0.30) are obtained with such a configuraton. The pulse duration is measured by a second-harmonic generation (SHG) correlation method and an ultrafast streak camera. Theoretical investigations of mode locking based on the time-domain approach and pulse propagation through the elements of the ring laser cavity are carried out. The laser medium is considered to be divided into two parts-the amplifying and absorbing regions. The steady state pulse parameters (duration, energy, and asymmetry) are derived from the computer simulation and are compared with the experiment. The effects of gain and absorber saturation are included in the treatment. Copyright © 1985 by The Institute of Electrical and Electronics Engineers, Inc

DIRECT DETECTION OF PICOSECOND PULSES EMITTED BY AN INJECTION LASER WITH ACTIVE MODE LOCKING.

An Agat-SF linear-scan streak image-converter camera was used to record output pulses of 2. 7 psec duration generated by an injection laser with an external dispersive resonator operated in the active mode-locking regime. The duration of the pulses was determined by the reciprocal of the spectral width and the product of the duration and the spectral width was 0. 30

Subpicosecond Pulse Generation by a Tandem-Type AlGaAs DH Laser with Colliding Pulse Mode Locking

Experimental results of colliding pulse mode locking (CPM) of a double-contact AlGaAs DH injection laser with an external cavity are presented. The laser has two amplifying sections and a passive umpumped segment located between them which exhibited saturable absorption action. Ultrashort pulses propagating in opposite directions collided in the absorber and pulse shortening occurred. Bursts of 0.8 ps IFWHM) pulses at a 710 MHz repetition rate are obtained by means of CPM. The pulse duration is measured by a second harmonic generation correlation method and an ultra fast streak camera. Copyright © 1986 by The Institute of Electrical and Electronics Engineers, Inc