SAMHD1 expression contributes to doxorubicin resistance and predicts survival outcomes in diffuse large B-cell lymphoma patients

Diffuse large B-cell lymphoma (DLBCL) is a commonly diagnosed, aggressive non-Hodgkin's lymphoma. While R-CHOP chemoimmunotherapy is potentially curative, about 40% of DLBCL patients will fail, highlighting the need to identify biomarkers to optimize management. SAMHD1 has a dNTPase-independent role in promoting resection to facilitate DNA double-strand break (DSB) repair by homologous recombination. We evaluated the relationship of SAMHD1 levels with sensitivity to DSB-sensitizing agents in DLBCL cells and the association of SAMHD1 expression with clinical outcomes in 79 DLBCL patients treated with definitive therapy and an independent cohort dataset of 234 DLBCL patients. Low SAMHD1 expression, Vpx-mediated, or siRNA-mediated degradation/depletion in DLBCL cells was associated with greater sensitivity to doxorubicin and PARP inhibitors. On Kaplan-Meier log-rank survival analysis, low SAMHD1 expression was associated with improved overall survival (OS), which on subset analysis remained significant only in patients with advanced stage (III-IV) and moderate to high risk (2-5 International Prognostic Index (IPI)). The association of low SAMHD1 expression with improved OS remained significant on multivariate analysis independent of other adverse factors, including IPI, and was validated in an independent cohort. Our findings suggest that SAMHD1 expression mediates doxorubicin resistance and may be an important prognostic biomarker in advanced, higher-risk DLBCL patients.

Lasing emission from an evaporating layered microdroplet

We report the first observations, to our knowledge, of lasing emission from a single, evaporating, layered, micrometer-sized droplet. The droplet consists of an ~7.9-microm-radius glass core covered by a liquid shell of an initial 3 x 10(-4) M Rhodamine 6G dye-doped glycerin/water solution. After pumping by a doubled (532 nm) Nd:YAG pulsed laser, droplet lasing occurs over a range of shell thicknesses from ~14.5 to ~0.4 microm. At the smallest shell thickness, a dramatic increase in both the number and intensity of the lasing peaks occurs, in addition to a large (>40-nm) blue shift in the spectral bandwidth of lasing emission. A discussion of possible enhancement mechanisms responsible for these novel findings is given.

Observation of suppression of morphology-dependent resonances in singly levitated micrometer-sized droplets

Suppression of morphology-dependent resonances of the light elastically scattered by a laser-illuminated, micrometer-sized droplet is reported. A single nonabsorbing droplet is levitated by using an electrodynamic quadrupole trap, and the scattered light is monitored as the droplet slowly evaporates. The size of the droplet is approximated by using the instability characteristics of the electrodynamic trap. To determine the refractive index and droplet radius precisely, the experimental scattering curve is fitted to a scattering curve that is generated from Mie theoretical calculations. The procedure is then repeated for absorbing droplets. The quality factor Q of each experimental resonance is determined and used to quantify the suppression effect. A dramatic suppression of narrow resonances occurs with increased absorption, whereas little or no effect is seen in moderate to broad resonances.