Owing to the prevalence of the JAK2V617F mutation in myeloproliferative neoplasms (MPNs), its constitutive activity, and ability to recapitulate the MPN phenotype in mouse models, JAK2V617F kinase is ...an attractive therapeutic target. We report the discovery and initial characterization of the orally bioavailable imidazopyridazine, LY2784544, a potent, selective and ATP-competitive inhibitor of janus kinase 2 (JAK2) tyrosine kinase. LY2784544 was discovered and characterized using a JAK2-inhibition screening assay in tandem with biochemical and cell-based assays. LY2784544 in vitro selectivity for JAK2 was found to be equal or superior to known JAK2 inhibitors. Further studies showed that LY2784544 effectively inhibited JAK2V617F-driven signaling and cell proliferation in Ba/F3 cells (IC50=20 and 55 nM, respectively). In comparison, LY2784544 was much less potent at inhibiting interleukin-3-stimulated wild-type JAK2-mediated signaling and cell proliferation (IC50=1183 and 1309 nM, respectively). In vivo, LY2784544 effectively inhibited STAT5 phosphorylation in Ba/F3-JAK2V617F-GFP (green fluorescent protein) ascitic tumor cells (TED50=12.7 mg/kg) and significantly reduced (P<0.05) Ba/F3-JAK2V617F-GFP tumor burden in the JAK2V617F-induced MPN model (TED50=13.7 mg/kg, twice daily). In contrast, LY2784544 showed no effect on erythroid progenitors, reticulocytes or platelets. These data suggest that LY2784544 has potential for development as a targeted agent against JAK2V617F and may have properties that allow suppression of JAK2V617F-induced MPN pathogenesis while minimizing effects on hematopoietic progenitor cells.
Glycogen synthase kinase-3 (GSK3) is involved in signaling from the insulin receptor. Inhibitors of GSK3 are expected to effect lowering of plasma glucose similar to insulin, making GSK3 an ...attractive target for the treatment of type 2 diabetes. Herein we report the discovery of a series of potent and selective GSK3 inhibitors. Compounds 7 − 12 show oral activity in an in vivo model of type II diabetes, and 9 and 12 have desirable PK properties.
MDL 105,212 has been identified as a potent, nonpeptide NK-1 and NK-2 receptor antagonist that inhibits effects of substance P and neurokinin A in vitro and in vivo (Kudlacz et al., 1996). In the ...present study, the compound inhibited capsaicin-induced respiratory effects after p.o. administration (5-50 mg/kg) to conscious guinea pigs; nearly complete inhibition of dyspnea and cough was observed 1 hr after 50 mg/kg p.o., and efficacy persisted for approximately 11 hr. MDL 105,212 reduced pulmonary insufflation pressure and microvascular leakage in ovalbumin-sensitized animals in response to antigen-challenge relative to vehicle-treated animals. Attenuation of early-phase allergic responses may result from MDL 105,212 inhibition of antigen-induced histamine release from sensitized guinea pig lung observed in vitro. Airway hyperresponsiveness to methacholine occurred 24 hr after antigen-challenge in ovalbuminsensitized guinea pigs; this effect was inhibited by pretreatment with MDL 105,212 (50 mg/kg p.o.) 1 hr before ovalbumin exposure without affecting increased bronchoalveolar lavage eosinophil numbers. These data suggest that sensory neuropeptides play a role in some aspects of allergic airway responses and that tachykinin receptor antagonists may be useful in treatment of atopic respiratory diseases.
We have identified and characterized a novel, potent, nonselective tachykinin receptor antagonist, MDL 105,212A (R)-1-2-3-(3,4- dichlorophenyl)-1-(3,4,5-trimethoxybenzoyl)-pyrrolidin-3-yl -ethyl- ...4-phenylpiperidine-4-carboxamide, hydrochloride. The compound binds with low nanomolar affinity and species specificity to human NK-1 and NK-2 receptors as well as to guinea pig NK-3 receptors. In vitro functional assays are consistent with potent competitive antagonism of substance P-(SP) or neurokinin A-(NKA) induced 3H-inositol phosphate accumulation in NK-1 or NK-2 monoreceptor cell lines with pA2 values of 8.19 and 8.67, respectively. Its ability to inhibit SP, NKA and capsaicin-mediated respiratory effects was examined in guinea pigs in vivo. MDL 105,212A attenuated SP-induced airway plasma protein extravasation (ED50 = 0.20 mg/kg, i.v.), NKA-induced respiratory collapse (ED50 = 5 mg/kg, i.v) and inhibited capsaicin-induced increases in pulmonary insufflation pressure (ED50 = 0.5 mg/kg, i.v.). Conscious guinea pigs responded to capsaicin aerosol exposure with dyspnea, coughs and gasps (significant respiratory events) and plasma protein extravasation. MDL 105,212A inhibited these responses in a dose-dependent manner after i.v. (ED50 = 5 mg/kg) or oral (ED50 = 50 mg/kg) administration. These data suggest that MDL 105,212A is a potent NK-1 and NK-2 receptor antagonist based on in vitro activity and its ability to inhibit SP and NKA mediated respiratory effects in vivo after exogenous administration or endogenous release and hence may be a useful therapeutic agent in neuroinflammatory disorders such as asthma in which a role for both tachykinins in the pathogenesis of the disease has been postulated.
The effects on phytoplankton and limnetics of two different types of suspended sediments and their interactions with P loading were tested in a small North Carolina piedmont lake. Limnocorrals were ...used in a complete, triplicated six-treatment, blocked design. Treatments were loaded with P, kaolinitic clay (K), K+P, montmorillonitic clay (M), and M+P. M caused more turbidity and stayed in suspension longer than K. Consequently, the light-dependent parameters, net community productivity (NCP), chlorophyll concentration, and algal density were lowest in the M and highest in the P treatment. Combined P and clay loading promoted clearing for both sediments and mitigated their effects on algal densities and NCP. Flagellated algae and nonfilamentous cyanophytes dominated the control community. The P treatment had blooms of Anabaena. Without fertilization, both clays resulted in sparse, flagellate-dominated communities. The M+P community, like that of the P treatment, was dominated by Anabaena, but total algal densities were suppressed. In contrast, the K+P community lacked Anabaena and was similar to the control in algal quantity and composition.
Acute myeloid leukemia (AML) is a life-threatening malignancy with limited treatment options in chemotherapy-refractory patients. A first-in-human dose study was designed to investigate a safe and ...biologically effective dose range for LY2457546, a novel multikinase inhibitor, in patients with relapsed AML.
In this nonrandomized, open-label, dose escalation Phase I study, LY2457546 was administered orally once a day. Safety, pharmacokinetics, changes in phosphorylation of target kinases in AML blasts, and risk of drug-drug interactions (DDI) were assessed.
Five patients were treated at the starting and predicted minimal biologically effective dose of 50 mg/day. The most commonly observed adverse events were febrile neutropenia, epistaxis, petechiae, and headache. The majority of adverse events (81%) were Grade 1 or 2. One patient had generalized muscle weakness (Grade 3), which was deemed to be a dose-limiting toxicity. Notably, the pharmacokinetic profile of LY2457546 showed virtually no elimination of LY2457546 within 24 hours, and thus prevented further dose escalation. No significant DDI were observed. Ex vivo flow cytometry studies showed downregulation of the phosphoproteins, pcKIT, pFLT3, and pS6, in AML blasts after LY2457546 administration. No medically relevant responses were observed in the five treated patients.
No biologically effective dose could be established for LY2457546 in chemotherapy-resistant AML patients. Lack of drug clearance prevented safe dose escalation, and the study was terminated early. Future efforts should be made to develop derivatives with a more favorable pharmacokinetic profile.
The traditional view of the planktonic food web describes consumption of inorganic nutrients by photoautotrophic phytoplankton, which in turn supports zooplankton and ultimately higher trophic ...levels. Pathways centred on bacteria provide mechanisms for nutrient recycling. This structure lies at the foundation of most models used to explore biogeochemical cycling, functioning of the biological pump, and the impact of climate change on these processes. We suggest an alternative new paradigm, which sees the bulk of the base of this food web supported by protist plankton communities that are mixotrophic - combining phototrophy and phagotrophy within a single cell. The photoautotrophic eukaryotic plankton and their heterotrophic microzooplankton grazers dominate only during the developmental phases of ecosystems (e.g. spring bloom in temperate systems). With their flexible nutrition, mixotrophic protists dominate in more-mature systems (e.g. temperate summer, established eutrophic systems and oligotrophic systems); the more-stable water columns suggested under climate change may also be expected to favour these mixotrophs. We explore how such a predominantly mixotrophic structure affects microbial trophic dynamics and the biological pump. The mixotroph-dominated structure differs fundamentally in its flow of energy and nutrients, with a shortened and potentially more efficient chain from nutrient regeneration to primary production. Furthermore, mixotrophy enables a direct conduit for the support of primary production from bacterial production. We show how the exclusion of an explicit mixotrophic component in studies of the pelagic microbial communities leads to a failure to capture the true dynamics of the carbon flow. In order to prevent a misinterpretation of the full implications of climate change upon biogeochemical cycling and the functioning of the biological pump, we recommend inclusion of multi-nutrient mixotroph models within ecosystem studies.
In January 2003, the US Environmental Protection Agency sponsored a “roundtable discussion” to develop a consensus on the relationship between eutrophication and harmful algal blooms (HABs), ...specifically targeting those relationships for which management actions may be appropriate. Academic, federal, and state agency representatives were in attendance. The following seven statements were unanimously adopted by attendees based on review and analysis of current as well as pertinent previous data:
(1)
Degraded water quality from increased nutrient pollution promotes the development and persistence of many HABs and is one of the reasons for their expansion in the U.S. and other nations;
(2)
The composition–not just the total quantity–of the nutrient pool impacts HABs;
(3)
High-biomass blooms must have exogenous nutrients to be sustained;
(4)
Both chronic and episodic nutrient delivery promote HAB development;
(5)
Recently developed tools and techniques are already improving the detection of some HABs, and emerging technologies are rapidly advancing toward operational status for the prediction of HABs and their toxins;
(6)
Experimental studies are critical to further the understanding about the role of nutrients in HABs expression, and will strengthen prediction and mitigation of HABs; and
(7)
Management of nutrient inputs to the watershed can lead to significant reduction in HABs.
Supporting evidence and pertinent examples for each consensus statement are provided herein.
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