Design and installation of a ferromagnetic wall in tokamak geometry

Low-activation ferritic steels are leading material candidates for use in next-generation fusion development experiments such as a prospective component test facility and DEMO power reactor. Understanding the interaction of plasmas with a ferromagnetic wall will provide crucial physics for these facilities. In order to study ferromagnetic effects in toroidal geometry, a ferritic wall upgrade was designed and installed in the High Beta Tokamak-Extended Pulse (HBT-EP). Several material options were investigated based on conductivity, magnetic permeability, vacuum compatibility, and other criteria, and the material of choice (high-cobalt steel) is characterized. Installation was accomplished quickly, with minimal impact on existing diagnostics and overall machine performance, and initial results demonstrate the effects of the ferritic wall on plasma stability.

MDM2 antagonists synergize broadly and robustly with compounds targeting fundamental oncogenic signaling pathways

While MDM2 inhibitors hold great promise as cancer therapeutics, drug resistance will likely limit their efficacy as single agents. To identify drug combinations that might circumvent resistance, we screened for agents that could synergize with MDM2 inhibition in the suppression of cell viability. We observed broad and robust synergy when combining MDM2 antagonists with either MEK or PI3K inhibitors. Synergy was not limited to cell lines harboring MAPK or PI3K pathway mutations, nor did it depend on which node of the PI3K axis was targeted. MDM2 inhibitors also synergized strongly with BH3 mimetics, BCR-ABL antagonists, and HDAC inhibitors. MDM2 inhibitor-mediated synergy with agents targeting these mechanisms was much more prevalent than previously appreciated, implying that clinical translation of these combinations could have far-reaching implications for public health. These findings highlight the importance of combinatorial drug targeting and provide a framework for the rational design of MDM2 inhibitor clinical trials.

Melatonin implants do not alter estrogen feedback or advance puberty in gilts

Puberty in pigs is often delayed during late summer and autumn, with long daylength the most likely cause. We hypothesised (1) that gilts born around the shortest day would have a later release from the negative feedback actions of estradiol than gilts born around the spring equinox and (2) melatonin treatment would result in an earlier release from estradiol negative feedback and advance the onset of puberty in gilts born around the spring equinox. We first determined the optimal number of estradiol implants required to monitor the release from estradiol negative feedback in ovariectomised gilts. Secondly we determined whether melatonin implants altered negative feedback in 4 cohorts of ovariectomised gilts born between the winter solstice and spring equinox, and in the following year whether melatonin altered the time of the first ovulation in 5 cohorts of intact gilts born between the winter solstice and spring equinox. Plasma LH and FSH increased between 126 and 210d of age (P<0.001) in each cohort (season), but there was no effect of cohort, melatonin treatment or interactions (P>0.05). Age at first detection of elevated plasma progesterone in untreated, intact gilts decreased across the 4 cohorts (P<0.05). Melatonin treatment of intact gilts failed to advance the age of puberty irrespective of their season of birth (P>0.05). In conclusion, while we confirmed that estradiol sensitivity is decreased as gilts age, we failed to demonstrate any effects of season or melatonin on estradiol feedback or melatonin on puberty.

Abstract 3712: HGF mediated resistance to BRAF inhibition in BRAF V600E mutant melanoma xenograft models

Background: A key obstacle in the treatment of cancer is resistance to targeted therapy. Recent reports suggest that growth factors and their receptors may play a role in mediating this resistance. HGF/MET signaling has been shown to play a role in mediating resistance to BRAF inhibitors in BRAF mutant melanoma. We studied the role of HGF/MET in mediating resistance to BRAF inhibition in BRAF mutant melanoma xenografts, comparing models of systemic and local HGF expression and evaluating the ability of a MET inhibitor to reverse HGF mediated resistance. The underlying mechanisms of this resistance were evaluated by monitoring changes in PI3K and MAPK signaling. Our data suggest that elevated local HGF expression may be required for resistance to BRAF inhibition in vivo and that resistance can be reversed by treatment with a MET inhibitor.

Methods: To model systemic HGF expression, mice bearing G361 melanoma xenografts were treated with recombinant adeno-associated virus containing an expression cassette for human HGF (AAV-HGF) or GFP as control. Mice were treated with C-1 (10 mg/kg, QD, PO), a BRAF inhibitor, or vehicle, and tumor growth was monitored. Local HGF expression was modeled using G361 xenografts engineered to express HGF under the control of an inducible promoter (tet-HGF). Mice bearing G361 tet-HGF xenografts, with or without doxycycline, were treated and monitored as described above. A follow up study was performed in G361 tet-HGF xenografts to measure the ability of AMG 337 (20 mg/kg, BID, PO), a selective MET inhibitor, to attenuate the HGF mediated rescue of BRAF inhibition. To monitor effects on the PI3K and MAPK pathways, pAKT and pERK levels were measured in tumors. Plasma and tumor HGF levels were also measured.

Results: Systemic expression of HGF via AAV-HGF treatment failed to rescue G361 xenografts from the growth inhibitory effects of C1. In contrast, local doxycycline-induced expression of HGF in mice harboring G361 tet-HGF xenografts conveyed significant (p&lt;0.001) rescue of tumor growth, suggesting that local HGF expression may be required to mediate BRAF inhibitor resistance. Elevated pAKT and pERK levels were detected in HGF rescued tumors, suggesting that PI3K and MAPK signaling pathways play a role in conveying HGF mediated resistance. Combined treatment with AMG 337 prevented the HGF mediated rescue of BRAF inhibition, confirming the role of MET signaling in this rescue mechanism. Plasma HGF levels in mice from the systemic HGF expression groups exceeded those in the local groups (3,049 and 195 pg/mL). However, tumor HGF levels were higher in the local expression groups compared to the systemic groups (26,400 and 477 pg/mL).

Conclusion: Here we demonstrate the role for HGF/MET signaling in mediating resistance to BRAF inhibitors in melanoma and suggest that monitoring HGF levels may be of clinical utility for predicting response to BRAF inhibition and in defining the opportunity for combination therapy with MET inhibitors.

Citation Format: Keegan Cooke, Guo Huang, Sean Caenepeel, Hong Ma, Cherylene Plewa, Ki Jeong Lee, Angela Coxon, Paul E. Hughes, Pedro Beltran. HGF mediated resistance to BRAF inhibition in BRAF V600E mutant melanoma xenograft models. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3712. doi:10.1158/1538-7445.AM2014-3712

Human and bovine viruses in the Milwaukee River watershed: hydrologically relevant representation and relations with environmental variables

To examine the occurrence, hydrologic variability, and seasonal variability of human and bovine viruses in surface water, three stream locations were monitored in the Milwaukee River watershed in Wisconsin, USA, from February 2007 through June 2008. Monitoring sites included an urban subwatershed, a rural subwatershed, and the Milwaukee River at the mouth. To collect samples that characterize variability throughout changing hydrologic periods, a process control system was developed for unattended, large-volume (56-2800 L) filtration over extended durations. This system provided flow-weighted mean concentrations during runoff and extended (24-h) low-flow periods. Human viruses and bovine viruses were detected by real-time qPCR in 49% and 41% of samples (n=63), respectively. All human viruses analyzed were detected at least once including adenovirus (40% of samples), GI norovirus (10%), enterovirus (8%), rotavirus (6%), GII norovirus (1.6%) and hepatitis A virus (1.6%). Three of seven bovine viruses analyzed were detected including bovine polyomavirus (32%), bovine rotavirus (19%), and bovine viral diarrhea virus type 1 (5%). Human viruses were present in 63% of runoff samples resulting from precipitation and snowmelt, and 20% of low-flow samples. Maximum human virus concentrations exceeded 300 genomic copies/L. Bovine viruses were present in 46% of runoff samples resulting from precipitation and snowmelt and 14% of low-flow samples. The maximum bovine virus concentration was 11 genomic copies/L. Statistical modeling indicated that stream flow, precipitation, and season explained the variability of human viruses in the watershed, and hydrologic condition (runoff event or low-flow) and season explained the variability of the sum of human and bovine viruses; however, no model was identified that could explain the variability of bovine viruses alone. Understanding the factors that affect virus fate and transport in rivers will aid watershed management for minimizing human exposure and disease transmission.

Lactation estrus induction in multi- and primiparous sows in an Australian commercial pork production system

This study evaluated the effect of full physical boar exposure and split weaning on the incidence of lactation estrus within a large commercial piggery. A total of 299 multiparous (MP; parity 2.5 ± 0.03) and 303 primiparous (PP) sows of Large White × Duroc × Landrace genetics were individually housed in conventional farrowing crates from 1 wk before expected farrowing until weaning on Day 30.7 ± 0.05 postparturition. Before shed entry, sows were allocated randomly within parity to receive either boar exposure (BE; n = 454) or no BE (No BE; n = 149). Sows assigned to receive BE were then allocated to 1 of 2 litter size treatments: litter size unchanged (BE; n = 302) or BE and the litter permanently reduced (split weaned) to 7 piglets (BESPW7; n = 152) on Day 18 of lactation. From Day 18 of lactation until weaning, sows in both BE treatments were taken daily to a detection mating area where they received 15 min of full physical BE and were artificially inseminated at the first observed estrus. Providing sows with BE increased the incidence of lactation estrus, with a further increase observed when litter size was reduced to 7 piglets (16% No BE vs. 62% BE and 75% BESPW7; P < 0.05). Multiparous sows exhibited a greater incidence of lactation estrus than PP sows irrespective of treatment (81 compared to 52%, respectively; P < 0.05). Both MP and PP sows exhibited an increased incidence of lactation estrus when a portion of the litter was removed (MP: 76 vs. 89% and PP: 47 vs. 61%; P < 0.05). Farrowing rates were higher in BE MP sows mated postweaning and all BESPW7 sows mated postweaning when compared to their counterparts mated in lactation (P < 0.05). Percentage live weight loss over the course of lactation was greatest for sows in the No BE compared to the BE and BESPW7 treatments (7.7% ± 0.5 vs. 5.4% ± 0.3 and 4.5% ± 0.4, respectively; P < 0.05). Between Day 17 and weaning, piglets suckling sows in the BESPW7 treatment had a higher average weight gain than piglets suckling sows with a full litter (3.5 ± 0.06 vs. 3.1 ± 0.05 kg; P < 0.05). In conclusion these data suggest that providing MP sows with BE is effective at stimulating a synchronous lactation estrus while PP sows require, in addition to BE, a reduction in suckled litter size to 7 piglets.

Split weaning increases the incidence of lactation oestrus in boar-exposed sows

This study evaluated the effect of split weaning and fence-line boar exposure during lactation on the incidence of lactation oestrus. Large White and Large White × Landrace sows (parity 2.9 ± 0.17; mean ± SEM) were housed in conventional farrowing crates from day -4 to 30 post-parturition. Four treatments (n = 18) were used: control (SPW0): continuous lactation of 10 piglets with all piglets weaned on day 30 of lactation; and three split wean (SPW) treatments with 3 (SPW3), 5 (SPW5) or 7 (SPW7) of the heaviest piglets removed from the sow on day 18 lactation. From day 18 lactation all sows received 15 min daily, fence-line boar exposure in a detection mating area. Fewer sows in the SPW0 treatment (56% (10/18)) expressed a lactation oestrus compared to the SPW3, SPW5, and SPW7 treatments (83%; 89%; 94%, respectively). SPW0 sows had a lower subsequent total born compared to SPW5 or SPW7 sows (8.9 ± 1.1 vs. 12.5 ± 1.0 and 13.1 ± 1.1, respectively). Between day 18 and 30 of lactation, sows in SPW5 and SPW7 gained weight (4.5 ± 1.4 and 1.9 ± 1.4 kg, respectively) whereas SPW0 and SPW3 sows lost weight (4.9 ± 1.4 and 2.9 ± 1.4 kg, respectively) (P<0.05). Split weaned piglets were heavier at day 17 of age by 1.0 kg however by day 40 of age no weight differences were observed between piglets weaned on day 18 compared to day 30 (P<0.05). In conclusion, split weaning coupled with fence-line boar exposure in late lactation induced lactation oestrus in a higher proportion of sows compared to those suckling a normal litter size.

Selective class I phosphoinositide 3-kinase inhibitors: optimization of a series of pyridyltriazines leading to the identification of a clinical candidate, AMG 511

The phosphoinositide 3-kinase family catalyzes the phosphorylation of phosphatidylinositol-4,5-diphosphate to phosphatidylinositol-3,4,5-triphosphate, a secondary messenger which plays a critical role in important cellular functions such as metabolism, cell growth, and cell survival. Our efforts to identify potent, efficacious, and orally available phosphatidylinositol 3-kinase (PI3K) inhibitors as potential cancer therapeutics have resulted in the discovery of 4-(2-((6-methoxypyridin-3-yl)amino)-5-((4-(methylsulfonyl)piperazin-1-yl)methyl)pyridin-3-yl)-6-methyl-1,3,5-triazin-2-amine (1). In this paper, we describe the optimization of compound 1, which led to the design and synthesis of pyridyltriazine 31, a potent pan inhibitor of class I PI3Ks with a superior pharmacokinetic profile. Compound 31 was shown to potently block the targeted PI3K pathway in a mouse liver pharmacodynamic model and inhibit tumor growth in a U87 malignant glioma glioblastoma xenograft model. On the basis of its excellent in vivo efficacy and pharmacokinetic profile, compound 31 was selected for further evaluation as a clinical candidate and was designated AMG 511.

Abstract 2805: In vitro characterization of AMG 511, a potent and selective class I PI3K inhibitor for the treatment of cancer

The PI3K signaling pathway is frequently activated in cancer and has been implicated in many aspects of tumor growth and survival. Inhibition of this pathway represents a potential therapeutic path for the treatment of cancer. This study evaluated the in vitro characteristics of AMG 511, a potent and selective pan class I PI3K inhibitor exhibiting IC50 values of 8, 11, 2, and 6 nM against the PI3K β, α, β, and ≤ isoforms respectively. AMG 511 was shown to be inactive against members of the closely related phosphoinositide 3 kinase related kinases (PIKK) family of kinases and did not inhibit mTOR, hVPS34, PI4Kα or PI4Kα in-vitro (IC50 values &gt; 1 μM). In addition, AMG 511 was inactive against a majority of protein kinases (372) in the human kinome as measured by in-vitro binding assays. AMG 511 inhibited PI3K pathway signaling in U87 MG glioblastoma cells as determined by dose-dependent reduction in AKT S473 phosphorylation (IC50 = 4 nM). AKT inhibition resulted in a concomitant reduction in PRAS40 phosphorylation (IC50 = 23 nM), a downstream effector of AKT. Reduced phosphorylation of mTORC1 substrates p70S6K (IC50 = 30 nM) and S6 (IC50 = 70 nM) but not 4EBP1 (T37/46), was also detected in U87 MG cells, suggesting that upstream blockade of PI3K pathway signaling with AMG 511 treatment leads to a selective reduction in downstream mTORC1 activity. Given the well documented role of mTORC1 in cap-dependent translation we profiled AMG 511 in a methionine-analog incorporation assay in U87 MG cells. However, no significant inhibition of bulk translation was observed following treatment with AMG 511 in U87 MG cells. Treatment of U87 MG cells with AMG 511 revealed a pronounced G1 arrest with a concurrent reduction in BrdU+ cells, detectable within 8 hours of treatment. This anti-proliferative effect was fully reversible by 18 hours following washout. In line with these anti-proliferative effects, reduced cyclin D1 levels and elevated p27 levels were detected within 4 hours of treatment. Minimal cell killing effects were detected with AMG 511 treatment in U87 MG cells as measured by induction of cleaved caspase-3 and DNA content &lt; 2N. AMG 511 was profiled across a large panel of tumor cell lines encompassing several tumor types including breast and lung. A majority of the cell lines tested exhibited sensitivity to AMG 511 with a subset exhibiting evidence for cell death upon treatment with AMG 511. Breast cancer cell lines harboring activating mutations in PI3Kα, loss of PTEN, or amplification of Her2 tended to show greater sensitivity to AMG 511 treatment. In conclusion, AMG 511 is a potent and selective pan class I PI3K inhibitor, capable of inhibiting PI3K signaling and inducing robust anti-proliferative effects via a G1 arrest in many tumor cell lines, with evidence of cell killing in a subset of lines.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2805. doi:1538-7445.AM2012-2805

Structure-activity relationships of phosphoinositide 3-kinase (PI3K)/mammalian target of rapamycin (mTOR) dual inhibitors: investigations of various 6,5-heterocycles to improve metabolic stability

N-(6-(6-Chloro-5-(4-fluorophenylsulfonamido)pyridin-3-yl)benzo[d]thiazol-2-yl)acetamide (1) is a potent and efficacious inhibitor of PI3Kα and mTOR in vitro and in vivo. However, in hepatocyte and in vivo metabolism studies, 1 was found to undergo deacetylation on the 2-amino substituent of the benzothiazole. As an approach to reduce or eliminate this metabolic deacetylation, a variety of 6,5-heterocyclic analogues were examined as an alternative to the benzothiazole ring. Imidazopyridazine 10 was found to have similar in vitro potency and in vivo efficacy relative to 1, while only minimal amounts of the corresponding deacetylated metabolite of 10 were observed in hepatocytes.

Phospshoinositide 3-kinase (PI3K)/mammalian target of rapamycin (mTOR) dual inhibitors: discovery and structure-activity relationships of a series of quinoline and quinoxaline derivatives

The phosphoinositide 3-kinase (PI3K) family catalyzes the ATP-dependent phosphorylation of the 3'-hydroxyl group of phosphatidylinositols and plays an important role in cell growth and survival. There is abundant evidence demonstrating that PI3K signaling is dysregulated in many human cancers, suggesting that therapeutics targeting the PI3K pathway may have utility for the treatment of cancer. Our efforts to identify potent, efficacious, and orally available PI3K/mammalian target of rapamycin (mTOR) dual inhibitors resulted in the discovery of a series of substituted quinolines and quinoxalines derivatives. In this report, we describe the structure-activity relationships, selectivity, and pharmacokinetic data of this series and illustrate the in vivo pharmacodynamic and efficacy data for a representative compound.

Nutritional restriction of pre-pubertal liveweight gain impairs ovarian follicle growth and oocyte developmental competence of replacement gilts

The objective was to investigate the effects of moderate restriction of pre- and peri-pubertal liveweight gain on ovarian development and oocyte meiotic competence. At 70 d of age, and 27.7 ± 0.4 kg liveweight (LW), 64 Large White/Landrace crossbred gilts were allocated to two treatment groups (n = 32 gilts/treatment); one group was fed to attain a LW of 70 kg at 161 d of age (LIGHT), while the other group was fed to reach 100 kg LW (HEAVY). At 161 d of age, half of the gilts in each group (n = 16) were fed to gain LW at 0.5 kg/d (LOW), while the remaining half (n = 16) were fed to gain LW at 1.0 kg/d (HIGH) between 161 and 175 d of age, at which point they were killed and ovaries collected. For each gilt, surface antral follicles were counted and aspirated according to three size categories: 1-2.9 mm (small); 3-6 mm (medium); and > 6 mm (large). Follicles were pooled for each size class and treatment. Cumulus-oocyte-complexes (COC) recovered from small and medium follicles were matured in vitro (IVM) for 44 to 46 h, and meiotic maturation assessed. There was an effect of treatment (LIGHT versus HEAVY) on the number of medium sized follicles: 25.1 ± 2.59 versus 34.3 ± 2.60 (P < 0.05). The ovaries of LOW gilts had more small follicles and fewer medium follicles compared to those of HIGH gilts: 92.8 ± 8.35 versus 59.8 ± 5.24, and 25.1 ± 2.59 versus 32.5 ± 2.86 (P < 0.05). Target LW at 161 d did not affect meiotic progression of oocytes. However, LOW compared to HIGH LW gain between 161 and 175 d resulted in fewer oocytes reaching MII (0.40 versus 0.54; P < 0.05). In conclusion, moderately restricting feed intake impaired follicle growth beyond 3 mm and reduced oocyte meiotic competence. Further, although a carry-over effect of long-term feed restriction on follicle growth was evident, acute changes in feed intake during the 14 d prior to ovary collection had the greatest effect on oocyte nuclear maturation in vitro.

Motesanib inhibits Kit mutations associated with gastrointestinal stromal tumors

Background

Activating mutations in Kit receptor tyrosine kinase or the related platelet-derived growth factor receptor (PDGFR) play an important role in the pathogenesis of gastrointestinal stromal tumors (GIST).

Methods

This study investigated the activity of motesanib, an inhibitor of vascular endothelial growth factor receptors (VEGFR) 1, 2, and 3; PDGFR; and Kit, against primary activating Kit mutants and mutants associated with secondary resistance to imatinib. Single- and double-mutant isoforms of Kit were evaluated for their sensitivity to motesanib or imatinib in autophosphorylation assays and in Ba/F3 cell proliferation assays.

Results

Motesanib inhibited Kit autophosphorylation in CHO cell lines expressing primary activating mutations in exon 9 (AYins503-504, IC₅₀ = 18 nM) and exon 11 (V560 D, IC₅₀ = 5 nM; Δ552-559, IC₅₀ = 1 nM). Motesanib also demonstrated activity against kinase domain mutations conferring imatinib resistance (V560D/V654A, IC₅₀ = 77 nM; V560D/T670I, IC₅₀ = 277 nM; Y823 D, IC₅₀ = 64 nM) but failed to inhibit the imatinib-resistant D816V mutant (IC₅₀ > 3000 nM). Motesanib suppressed the proliferation of Ba/F3 cells expressing Kit mutants with IC₅₀ values in good agreement with those observed in the autophosphorylation assays.

Conclusions

In conclusion, our data suggest that motesanib possesses inhibitory activity against primary Kit mutations and some imatinib-resistant secondary mutations.

Mixing gilts in early pregnancy does not affect embryo survival

There is general acceptance that mixing sows during the first 3 weeks of gestation is detrimental to embryo development and survival. However, there is a paucity of data describing the influence of group housing and remixing during the first 14 days of gestation on pregnancy outcomes. Using 96 purebred maternal (Large White)/terminal (Duroc) line gilts, the current study determined the effects of regrouping, and the timing of regrouping, during the pre-implantation period on embryo mortality. The study was conducted in 2 blocks, with 12 gilts allocated to each of 4 treatments in each block. At 175 days of age, the combination of PG600 and 20 min of daily physical boar contact was used to stimulate puberty, with boar contact resuming 12 days after first detection of oestrus and gilts receiving two artificial inseminations (AIs), 24 h apart, at their second oestrus. After their first AI gilts were allocated to one of four treatment groups (n=12 gilts/treatment). Gilts in one treatment group were housed individually in stalls (STALL). The remaining gilts continued to be housed in their pre-AI groups and were either not remixed (NOMIX), or remixed to form new groups on day 3/4 (RMIXD3/4) or day 8/9 (RMIXD8/9) of gestation (day 0=day of first detection of second oestrus and first insemination). Group-housed gilts were housed in groups of 6, with a space allowance of 2.4 m2/gilt. All gilts were fed once a day (2.2 kg/gilt). Reproductive tracts were collected on day 26.6+/-0.13 of gestation, and the number of corpora lutea (CL) and viable embryos counted. Pregnancy rate was similar across all treatments, averaging 94.5% across the four treatment groups. The number of embryos present on day 26 of gestation was unaffected by housing treatments (P>0.05); gilts in the STALL, NOMIX, RMIXD3/4 and RMIXD8/9 groups possessed 13.2+/-0.67, 12.9+/-0.66, 14.1+/-0.46 and 13.8+/-0.57 embryos, respectively. Similarly, embryo survival rates were 0.91+/-0.04, 0.85+/-0.04, 0.91+/-0.02 and 0.87+/-0.05 for the STALL, NOMIX, RMIXD3.4 and RMIXD8/9 groups, respectively (P>0.05). In conclusion, the current data indicate that individually housing gilts immediately after their first AI does not improve embryo survival. There also appear to be no adverse effects on embryo development or survival when group-housed, mated gilts are remixed during the first 10 days of gestation.

Synthesis, structural analysis, and SAR studies of triazine derivatives as potent, selective Tie-2 inhibitors

A novel class of selective Tie-2 inhibitors was derived from a multi-kinase inhibitor 1. By reversing the amide connectivity and incorporating aminotriazine or aminopyridine hinge-binding moieties, excellent Tie-2 potency and KDR selectivity could be achieved with 3-substituted terminal aryl rings. X-ray co-crystal structure analysis aided inhibitor design. This series was evaluated on the basis of potency, selectivity, and rat pharmacokinetic parameters.

Evolution of a Highly Selective and Potent 2-(Pyridin-2-yl)-1,3,5-triazine Tie-2 Kinase Inhibitor

Inhibition of angiogenesis is a promising and clinically validated approach for limiting tumor growth and survival. The receptor tyrosine kinase Tie-2 is expressed almost exclusively in the vascular endothelium and is required for developmental angiogenesis and vessel maturation. However, the significance of Tie-2 signaling in tumor angiogenesis is not well understood. In order to evaluate the therapeutic utility of inhibiting Tie-2 signaling, we developed a series of potent and orally bioavailable small molecule Tie-2 kinase inhibitors with selectivity over other kinases, especially those that are believed to be important for tumor angiogenesis. Our earlier work provided pyridinyl pyrimidine 6 as a potent, nonselective Tie-2 inhibitor that was designed on the basis of X-ray cocrystal structures of KDR inhibitors 34 (triazine) and 35 (nicotinamide). Lead optimization resulted in pyridinyl triazine 63, which exhibited >30-fold selectivity over a panel of kinases, good oral exposure, and in vivo inhibition of Tie-2 phosphorylation.

Increasing the age of gilts at first boar contact improves the timing and synchrony of the pubertal response but does not affect potential litter size

One hundred and ninety-two Large White/Landrace crossbred gilts were used in this study. The study was conducted in two blocks, with 16 gilts allocated to each of six treatments in each block. The treatments compared the effects on puberty attainment of commencing boar exposure at 161, 182 or 203 days of age, and the effect of first mating gilts at either the pubertal or second oestrus on ovulation rate and early embryo survival. Boar contact took place in a detection-mating area (DMA), and consisted of 20 min/day of full contact with a vasectomized boar greater than ten months of age. Gilts were artificially inseminated at the allocated oestrus, with the reproductive tracts collected at 22.8+/-0.4 days after first mating (mean+/-S.E.M.), and the numbers of corpora lutea and viable embryos recorded. The age at which gilts attained puberty increased with the age at which boar exposure commenced. Mean gilt ages at puberty were 179.5+/-1.6, 191.7+/-1.2 and 210.3+/-0.9 days, respectively, when boar contact commenced at 161, 182 and 203 days of age, P<0.01. Mean days-to-puberty was significantly shorter when boar contact began at 182 and 203 days of age compared to 161 days of age (10.4+/-1.2 and 8.3+/-0.9 days versus 18.9+/-1.5 days, respectively, P<0.01). Similarly, commencing boar exposure at 182 or 203 days of age as opposed to 161 days of age significantly increased the proportion of gilts attaining puberty within 10 days of start of boar exposure (0.67 and 0.70 versus 0.24, P<0.01). Mean days-to-puberty and the synchrony of puberty attainment were similar when boar contact commenced at 182 and 203 days of age. There was no significant effect of mating oestrus or age of gilts at mating on ovulation rate, embryo number or embryo survival. In conclusion, the current data indicate that the timing and synchrony of puberty attainment is significantly improved when first boar exposure of gilts is delayed until 182 days of age. Further, it is evident that within the age range investigated, delaying first mating until the second oestrus does not significantly increase either ovulation rate or embryo number at day 20 post-mating.

C-terminal sequences in R-Ras are involved in integrin regulation and in plasma membrane microdomain distribution

The small GTPases R-Ras and H-Ras are highly homologous proteins with contrasting biological properties, for example, they differentially modulate integrin affinity: H-Ras suppresses integrin activation in fibroblasts whereas R-Ras can reverse this effect of H-Ras. To gain insight into the sequences directing this divergent phenotype, we investigated a panel of H-Ras/R-Ras chimeras and found that sequences in the R-Ras hypervariable C-terminal region including amino acids 175-203 are required for the R-Ras ability to increase integrin activation in CHO cells; however, the proline-rich site in this region, previously reported to bind the adaptor protein Nck, was not essential for this effect. In addition, we found that the GTPase TC21 behaved similarly to R-Ras. Because the C-termini of Ras proteins can control their subcellular localization, we compared the localization of H-Ras and R-Ras. In contrast to H-Ras, which migrates out of lipid rafts upon activation, we found that activated R-Ras remained localized to lipid rafts. However, functionally distinct H-Ras/R-Ras chimeras containing different C-terminal R-Ras segments localized to lipid rafts irrespective of their integrin phenotype.