Baculovirus production of fully-active phosphoinositide 3-kinase alpha as a p85alpha-p110alpha fusion for X-ray crystallographic analysis with ATP competitive enzyme inhibitors

Phosphoinositide 3-kinases have been targeted for therapeutic research because they are key components of a cell signaling cascade controlling proliferation, growth, and survival. Direct activation of the PI3Kalpha pathway contributes to the development and progression of solid tumors in breast, endometrial, colon, ovarian, and gastric cancers. In the context of a drug discovery effort, the availability of a robust crystallographic system is a means to understand the subtle differences between ATP competitive inhibitor interactions with the active site and their selectivity against other PI3Kinase enzymes. To generate a suitable recombinant design for this purpose, a p85alpha-p110alpha fusion system was developed which enabled the expression and purification of a stoichiometrically homogeneous, constitutively active enzyme for structure determination with potent ATP competitive inhibitors (Raha et al., in preparation) [56]. This approach has yielded preparations with activity and inhibition characteristics comparable to those of the full-length PI3Kalpha from which X-ray diffracting crystals were grown with inhibitors bound in the active site.

Multiple ganglion cysts (‘cystic ganglionosis’): an unusual presentation in a child

A case of multifocal and recurrent ganglion cysts is described. An 11-year-old boy was referred because of symptomatic cystic masses in the extremities since the age of 2 years. Over the years, he had experienced intermittent appearance of these lesions, which were associated with pain, but without any systemic manifestations. Magnetic resonance imaging (MRI) showed cystic lesions with synovio-capsular thickening along the temporomandibular joints (TMJ), atlanto-axial synovial articulation, and tendons and joints of the right wrist and hand. Histopathological examination of one lesion showed anastomosing fibro-connective tissue surrounded by a wall of smooth muscle and fibrous connective tissue, findings that were consistent with ganglion cyst. The early onset of the disease, as well as the involvement of multiple and unusual sites, including the TMJ, implies a genetic susceptibility to these lesions that we refer to as 'cystic ganglionosis'.

Phase II study of rabbit anti-thymocyte globulin, cyclosporine and granulocyte colony-stimulating factor in patients with aplastic anemia and myelodysplastic syndrome

We investigated efficacy and safety of rabbit anti-thymocyte globulin (rATG), cyclosporine and granulocyte colony-stimulating factor (G-CSF) as first-line therapy for patients with aplastic anemia (AA) and low or intermediate-1 or hypoplastic myelodysplastic syndrome (MDS). rATG 3.5 mg/kg (or 2.5 mg/kg per day for patients >or=55 years with MDS) was given for 5 days. Cyclosporine (5 mg/kg) and G-CSF (5 microg/kg) were given daily and continued for up to 6 months or longer. Responses were assessed about 3 and 6 months after therapy. Thirty-six patients have been enrolled on study and 32 patients treated; 25 were evaluable for a response (13 with AA, 12 with MDS); the rest are too early. The median age was 62 years (range, 20-83) for patients with AA and 63 (range, 42-80) for patients with MDS. Of 13 patients, 12 (92%) patients with AA responded (5 complete response (CR), 7 partial response (PR)), whereas of 12 patients, 4 (33%) patients with MDS responded (1 CR, 3 PR). For patients with AA, the median time to response (TTR) was 93 days (range, 79-623), whereas in the MDS group the median TTR was 111 days (range, 77-139). Grade III/IV toxicities were mainly cytopenias and neutropenic fever. Combination of rATG, cyclosporine and G-CSF is safe and effective as first-line treatment of AA and has significant activity in low-risk MDS.

The advantage of positive text-background polarity is due to high display luminance

Reading text from computer screens is better when text is printed in dark letters on light background (positive polarity) than when it is printed in light letters on dark background (negative polarity). An experiment is presented that tests whether this positive polarity advantage is due to the fact that overall display luminance is typically higher for positive than for negative polarity displays. To this end, text-background polarity and display luminance were manipulated independently. No positive polarity advantage was observed when overall display luminance of positive and negative polarity displays was equivalent. There was only an effect of display luminance, with better performance for the higher-luminance displays. This suggests that the positive polarity advantage is in fact due to the typically higher luminance of positive polarity displays. Readability of text presented on computer screens (e.g. on websites) is better when the overall display luminance level is high, as in positive polarity displays (dark letters on light background). Display polarity per se does not affect readability.

Phase I/II study of idarubicin (Ida), high-dose ara-C, and sorafenib (S) in patients (pts) younger than 65 years with acute myeloid leukemia (AML)

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Background: S is an oral multi-kinase inhibitor with activity against the Raf/ERK/MEK pathway and FLT3. It selectively induces apoptosis in FLT3-mutant human AML cell lines at nM concentrations. Methods: Objectives of this study are to determine the tolerability and efficacy of combination of S with chemotherapy. Ara-C 1.5 g/m2 over 24 hrs daily x 4 (x 3 for pts over 60) and Ida 12 mg/m2 daily x 3 are administered with S. In the phase I part, pts with relapsed AML were treated with escalating doses of S (400 mg qod, 400 mg daily, 400 mg bid) for 7 days during induction, and 400 mg bid was established as safe. Pts achieving CR receive up to 5 courses of consolidation with Ida 8 mg/m2 daily x 2 and Ara-C 0.75 g/m2 daily x 3 in addition to S 400 mg bid for up to 28 days per cycle repeated every 4 to 6 weeks. Maintenance is with S 400 mg bid for up to a year. Results: 10 pts (median age 34, range 21–58) with relapsed AML (median prior therapy 2, range 1–6) were treated in the phase I . 7 were FLT3-ITD positive. 4 achieved CR; 6 failed. In the phase II part, 45 pts (12 with FLT3-ITD and 2 with FLT3-TKD) were treated. Median age is 53 (range 18 - 65). Cytogenetics were diploid in 19, +8 in 5, -5/-7 in 5, 11q23 in 2, other in 14. Median presentation WBC was 4.9 x 109/L (range 0.6 - 122.7 x 109/L). 8 pts were FLT3-ITD+/NPM1-. 40 pts are evaluable for response and 85% achieved CR (n = 30) or CRp (n = 4) (13 of 14 FLT3 mutated pts); 5 pts are too early (1 FLT3 mutated). Most frequent grade 3 and higher related adverse events: hyperbilirubinemia (5), rash and hand-foot syndrome (3), raised transaminases (2), diarrhea (2), hypertension (2). With a median f/u of 5.4 mo (range, 0.5 - 11.3), the probability of survival at 6 mo is 81.6%. 5 pts have relapsed; median CR duration has not been reached, (range; 0.2+ - 10.6+ mo). Among pts with FLT3 mutation, 4 have relapsed and 9 remain in CR. Plasma inhibitory assay was performed using day 7 samples from 10 pts; mutant FLT3 was suppressed by all with 5-fold more potent suppression against mutant versus wild-type FLT3. Conclusions: S can be safely combined with IA; it has a high CR rate in frontline therapy of younger pts with AML, in particular those with FLT3 mutations. Correlative studies confirm potent activity of S against FLT3 signaling.

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Global-scale analyses of chemical ecology and population genetics in the invasive Argentine ant

Ants are some of the most abundant and ecologically successful terrestrial organisms, and invasive ants rank among the most damaging invasive species. The Argentine ant is a particularly well-studied invader, in part because of the extreme social structure of introduced populations, known as unicoloniality. Unicolonial ants form geographically vast supercolonies, within which territorial behaviour and intraspecific aggression are absent. Because the extreme social structure of introduced populations arises from the widespread acceptance of conspecifics, understanding how this colonymate recognition occurs is key to explaining their success as invaders. Here, we present analyses of Argentine ant recognition cues (cuticular hydrocarbons) and population genetic characteristics from 25 sites across four continents and the Hawaiian Islands. By examining both hydrocarbon profiles and microsatellite genotypes in the same individual ants, we show that native and introduced populations differ in several respects. Both individual workers and groups of nestmates in the introduced range possess less diverse chemical profiles than ants in the native range. As previous studies have reported, we also find that introduced populations possess much lower levels of genetic diversity than populations in the native range. Interestingly, the largest supercolonies on several continents are strikingly similar to each other, suggesting that they arose from a shared introduction pathway. This high similarity suggests that these geographically far-flung ants may still recognize and accept each other as colonymates, thus representing distant nodes of a single, widely distributed supercolony. These findings shed light on the behaviour and sociality of these unicolonial invaders, and pose new questions about the history and origins of introduced populations.

A simple assay for detection of small-molecule redox activity

In addition to selecting molecules of pharmacological interest, high-throughput screening campaigns often generate hits of undesirable mechanism, which cannot be exploited for drug discovery as they lead to obvious problems of specificity and developability. Examples of undesirable mechanisms are target alkylation/acylation and compound aggregation. Both types of "promiscuous" mechanisms have been described in the literature, as have methods for their detection. In addition to these mechanisms, compounds can also inhibit by oxidizing susceptible enzyme targets, such as metalloenzymes and cysteine-using enzymes. However, this redox phenomenon has been documented infrequently, and an easy method for detecting this behavior is missing. In this article, the authors describe direct proof of small-molecule oxidation of a cysteine protease by liquid chromatography/tandem mass spectrometry, develop a simple assay to predict this oxidizing behavior by compounds, and show the utility of this assay by demonstrating its ability to distinguish nuisance redox compounds from well-behaved inhibitors in 3 historical GlaxoSmithKline drug discovery efforts.