The ubiquitin-specific protease USP47 is a novel beta-TRCP interactor regulating cell survival.

Ubiquitin-specific proteases (USPs) are a subclass of cysteine proteases that catalyze the removal of ubiquitin (either monomeric or chains) from substrates, thus counteracting the activity of E3 ubiquitin ligases. Although the importance of USPs in a multitude of processes, from hereditary cancer to neurodegeneration, is well established, our knowledge on their mode of regulation, substrate specificity and biological function is quite limited. In this study we identify USP47 as a novel interactor of the E3 ubiquitin ligase, Skp1/Cul1/F-box protein beta-transducin repeat-containing protein (SCF(beta-Trcp)). We found that both beta-Trcp1 and beta-Trcp2 bind specifically to USP47, and point mutations in the beta-Trcp WD-repeat region completely abolished USP47 binding, indicating an E3-substrate-type interaction. However, unlike canonical beta-Trcp substrates, USP47 protein levels were neither affected by silencing of beta-Trcp nor modulated in a variety of processes, such as cell-cycle progression, DNA damage checkpoint responses or tumor necrosis factor (TNF) pathway activation. Notably, genetic or siRNA-mediated depletion of USP47 induced accumulation of Cdc25A, decreased cell survival and augmented the cytotoxic effects of anticancer drugs. In conclusion, we showed that USP47, a novel beta-Trcp interactor, regulates cell growth and survival, potentially providing a novel target for anticancer therapies.

Synthesis of thick optical thin-film filters with a layer-peeling inverse-scattering algorithm.

We present an efficient and accurate method for synthesis of optical thin-film structures. The method is based on a differential inverse-scattering algorithm and considers therefore both phase and amplitude reflectance data. We apply the algorithm to the synthesis of filters with arbitrary index layers and two-material filters consisting of only high- and low-index layers. The layered structure is approximated by a stack of discrete reflectors with equal distance between all reflectors. This mirror stack is in turn determined from the desired, complex reflection spectrum by a layer-peeling inverse-scattering algorithm. The complexity of the design algorithm is approximately the same as that of the forward problem of computing the spectrum from a known structure.

Phase reconstruction from reflectivity in fiber Bragg gratings.

It is shown that a recently proposed phase-retrieval technique for Bragg gratings [Opt. Lett. 22, 93 (1997); J. Lightwave Technol. 15, 1314 (1997)] is not well suited for gratings with imperfections. The reconstructed group delay is in many cases not a more accurate estimate than the simulated group delay of the perfect, designed grating, independently of how small the errors in the grating structure are. The error in the group delay may be especially large near the zeros in the reflection spectrum.

Measuring the group delay of fiber Bragg gratings by use of end-reflection interference.

A new, simple method for characterization of fiber Bragg gratings is proposed. The group delay of the grating is obtained from measurement of the spectral reflectivity response of a grating that is interfering with a bare-fiber end reflection.

High-reflectivity fiber-optic bandpass filter designed by use of the iterative solution to the Gel'fand-Levitan-Marchenko equations.

A fiber Bragg grating bandpass filter has been investigated. The profile of the 3.1-cm-long grating was synthesized for high reflectivity and low dispersion by use of the iterative solution to the Gel'fand-Levitan-Marchenko equations. A grating designed according to this synthesis was written into a boron-codoped germanosilica fiber. The measured spectral response was in good agreement with simulations. The achieved in-band reflection was 97%, and the passband ripple was only 0.06 dB.

Evidence for the involvement of ecto-5'-nucleotidase (CD73) in drug resistance.

Increased ecto-5'-nucleotidase (ecto-5'NT) protein expression in several multidrug-resistant (MDR) cell lines, documented previously by our group, suggests that this enzyme is involved in drug resistance. Here, Northern blot analysis of selected cell lines and their MDR variants positively correlated ecto-5'NT protein with its mRNA expression. An inhibitor of ecto-5'NT enzymatic activity, alpha,beta-methyleneadenosine 5'-diphosphate (AMP-CP), was used to determine if functionally active enzyme had a role in drug resistance. AMP-CP (0.3 mM) reversed the resistance of ecto-5'NT-positive MDR cells (MCF7/A6, L1210/A) to doxorubicin, whereas it did not affect the doxorubicin sensitivity of the ecto-5'NT-negative parental cell lines or that of 2 ecto-5'NT-negative MDR cell lines (HL60/VCR and A2780/DX5). Furthermore, AMP-CP increased rhodamine uptake and inhibited rhodamine efflux from ecto-5'NT-positive MDR cells without affecting ecto-5'NT-negative MDR cells. The presence of exogenous adenosine (0.5 microM) circumvented AMP-CP-induced inhibition of rhodamine efflux from EL4/ADM cells. AMP-CP inhibited the growth of the ecto-5'NT-positive L1210/A MDR cells but had no effect on the growth of the parental cell line. Determination of intracellular ATP levels indicated that MDR cells which had increased ecto-5'NT expression also had a lower intracellular ATP level than their parental cells. Our results suggest that, in certain MDR cell lines, ecto-5'NT serves as a required accessory molecule in resistance mediated by ATP-dependent mechanisms and that growth-sustaining nucleosides are provided by this salvage pathway.

Sinusitis of the maxillary antrum.

Twenty-four adults with clinical evidence of sinusitis were studied by 65 needle punctures of the maxillary antrum. Fourteen of 15 sinuses with normal transillumination and 19 of 26 that were dull had normal aspirates, whereas 24 of 24 that were opaque had abnormal aspirates (P less than 0.001). Marked mucosal thickening as determined radiologically (Water's view) was associated with abnormal aspirates whereas lesser mucosal thickening was not (P less than 0.001). In acute sinusitis, there was a strong correlation between high aspirate leukocyte counts (greater than 1000 per cubic millimeter) and infection as manifested by bacterial titers of greater than 10(5) per milliliter or the isolation of virus fungus (P greater than 0.001). Anterior-nasal-swab cultures correlated poorly with direct aspirate culters. Organisms frequently recovered from the sinus included Haemophilus influenzae, Strepto coccus pneumoniae, and anaerobic bacteria. Rhinovirus was recovered twice. Antibiotics were usedful in patients with acute sinusitis if the organism was sensitive in vitro (P less than 0.001).