1,872 research outputs found
Influencing European Corn Borer (Lepidoptera: Crambidae) Aggregation Sites in Small Grain Crops
Reliable methods to attract European corn borer, Ostrinia nubilalis (Hübner), adults to small grain crops could be used to aggregate moths into small well-defined areas for control purposes or could be used in a resistance management program for delaying potential O. nubilalis resistance to transgenic corn. The objective of this research was to determine whether small-grain crops could be managed to influence O. nubilalis aggregation behavior. In farmer-managed oat, Atena sativa (L.), fields, more O. nubilalis adults were attracted to high-density patches of oat compared with standard patches of oat; no difference was found between patches of high-density oat and brome, Bromus spp. Numbers of O. nubilalis moths found in 6 barley, Hordeum vulgare (L.), and legume treatments (1995), and 4 oat/legume treatments (1996) were significantly different. The highest number of O. nubilalis adults were observed in barley planted with alfalfa, Medicago sativa (L.), followed by barley planted with crimson clover, Trifolium incarnatum(L.), barley planted with berseem, Trifolium alexandrinum (L.), barley planted with black medic, Medicago lupulina (L.), barley alone, and barley planted with lespedeza, Lespedeza stipulacea (Maximowicz). Double-planted oat attracted the highest number of O. nubilalis adults followed by oat planted with crimson clover, oat planted with alfalfa, and single-planted oat. Each study suggests that there is a positive correlation between moth aggregation and canopy area. Suggestions are made that timing canopy closure of a small-grain crop with peak O. nubilalis flight should maximize O. nubilalis aggregation and should thereby increase the efficacy of any control measures
Regulation of bombesin-stimulated cyclooxygenase-2 expression in prostate cancer cells
BACKGROUND: Cyclooxygenase-2 (COX-2) and the bombesin (BBS)-like peptide, gastrin-releasing peptide (GRP), have been implicated in the progression of hormone-refractory prostate cancer; however, a mechanistic link between the bioactive peptide and COX-2 expression in prostate cells has not been made. RESULTS: We report that BBS stimulates COX-2 mRNA and protein expression, and the release of prostaglandin E(2 )from the GRP receptor (GRPR)-positive, androgen-insensitive prostate cancer cell line, PC-3. BBS-stimulated COX-2 expression is mediated, in part, by p38(MAPK )and PI3 kinase (PI3K)/Akt pathways, and blocked by a GRPR antagonist. The PI3K/Akt pathway couples GRPR to the transcription factor, activator protein-1 (AP-1), and enhanced COX-2 promoter activity. Although BBS stimulates nuclear factor-kappaB (NF-κB) in PC-3, NF-κB does not regulate GRPR-mediated COX-2 expression. The p38(MAPK )pathway increases BBS-stimulated COX-2 expression by slowing the degradation of COX-2 mRNA. Expression of recombinant GRPR in the androgen-sensitive cell line LNCaP is sufficient to confer BBS-stimulated COX-2 expression via the p38(MAPK )and PI3K/Akt pathways. CONCLUSIONS: Our study establishes a mechanistic link between GRPR activation and enhanced COX-2 expression in prostate cancer cell lines, and suggests that inhibiting GRPR may, in the future, provide an effective therapeutic alternative to non-steroidal anti-inflammatory drugs for inhibiting COX-2 in patients with recurrent prostate cancer
Seeds of Change: Corn Seed Mixtures for Resistance Management and Integrated Pest Management
The use of mixtures of transgenic insecticidal seed and nontransgenic seed to provide an in-field refuge for susceptible insects in insect-resistance-management (IRM) plans has been considered for at least two decades. However, the U.S. Environmental Protection Agency has only recently authorized the practice. This commentary explores issues that regulators, industry, and other stakeholders should consider as the use of biotechnology increases and seed mixtures are implemented as a major tactic for IRM. We discuss how block refuges and seed mixtures in transgenic insecticidal corn, Zea mays L., production will influence integrated pest management (IPM) and the evolution of pest resistance. We conclude that seed mixtures will make pest monitoring more difficult and that seed mixtures may make IRM riskier because of larval behavior and greater adoption of insecticidal corn. Conversely, block refuges present a different suite of risks because of adult pest behavior and the lower compliance with IRM rules expected from farmers. It is likely that secondary pests not targeted by the insecticidal corn as well as natural enemies will respond differently to block refuges and seed mixtures
Inhibition of hydrogen sulfide biosynthesis sensitizes lung adenocarcinoma to chemotherapeutic drugs by inhibiting mitochondrial DNA repair and suppressing cellular bioenergetics
Therapeutic manipulation of the gasotransmitter hydrogen sulfide (H(2)S) has recently been proposed as a novel targeted anticancer approach. Here we show that human lung adenocarcinoma tissue expresses high levels of hydrogen sulfide (H(2)S) producing enzymes, namely, cystathionine beta-synthase (CBS), cystathionine gamma lyase (CSE) and 3-mercaptopyruvate sulfurtransferase (3-MST), in comparison to adjacent lung tissue. In cultured lung adenocarcinoma but not in normal lung epithelial cells elevated H(2)S stimulates mitochondrial DNA repair through sulfhydration of EXOG, which, in turn, promotes mitochondrial DNA repair complex assembly, thereby enhancing mitochondrial DNA repair capacity. In addition, inhibition of H(2)S-producing enzymes suppresses critical bioenergetics parameters in lung adenocarcinoma cells. Together, inhibition of H(2)S-producing enzymes sensitize lung adenocarcinoma cells to chemotherapeutic agents via induction of mitochondrial dysfunction as shown in in vitro and in vivo models, suggesting a novel mechanism to overcome tumor chemoresistance
Design and fabrication of 3D-printed anatomically shaped lumbar cage for intervertebra disc (IVD) degeneration treatment
Spinal fusion is the gold standard surgical procedure for degenerative spinal conditions when conservative therapies have been unsuccessful in rehabilitation of patients. Novel strategies are required to improve biocompatibility and osseointegration of traditionally used materials for lumbar cages. Furthermore, new design and technologies are needed to bridge the gap due to the shortage of optimal implant sizes to fill the intervertebral disc defect. Within this context, additive manufacturing technology presents an excellent opportunity to fabricate ergonomic shape medical implants. The goal of this study is to design and manufacture a 3D-printed lumbar cage for lumbar interbody fusion. Optimisations of the proposed implant design and its printing parameters were achieved via in silico analysis. The final construct was characterised via scanning electron microscopy, contact angle, x-ray micro computed tomography (μCT), atomic force microscopy, and compressive test. Preliminary in vitro cell culture tests such as morphological assessment and metabolic activities were performed to access biocompatibility of 3D-printed constructs. Results of in silico analysis provided a useful platform to test preliminary cage design and to find an optimal value of filling density for 3D printing process. Surface characterisation confirmed a uniform coating of nHAp with nanoscale topography. Mechanical evaluation showed mechanical properties of final cage design similar to that of trabecular bone. Preliminary cell culture results showed promising results in terms of cell growth and activity confirming biocompatibility of constructs. Thus for the first time, design optimisation based on computational and experimental analysis combined with the 3D-printing technique for intervertebral fusion cage has been reported in a single study. 3D-printing is a promising technique for medical applications and this study paves the way for future development of customised implants in spinal surgical applications
Glial cell line-derived neurotrophic factor influences proliferation of osteoblastic cells
Little is known about the role of neurotrophic growth factors in bone metabolism. This study investigated the short-term effects of glial cell line-derived neurotrophic factor (GDNF) on calvarial-derived MC3T3-E1 osteoblasts. MC3T3-E1 expressed GDNF as well as its canonical receptors, GFRα1 and RET. Addition of recombinant GDNF to cultures in serum-containing medium modestly inhibited cell growth at high concentrations; however, under serum-free culture conditions GDNF dose-dependently increased cell proliferation. GDNF effects on cell growth were inversely correlated with its effect on alkaline phosphatase (ALP) activity showing a significant dose-dependent inhibition of relative ALP activity with increasing concentrations of GDNF in serum-free culture medium. Live/dead and lactate dehydrogenase assays demonstrated GDNF did not significantly affect cell death or survival under serum-containing and serum-free conditions. The effect of GDNF on cell growth was abolished in the presence of inhibitors to GFR α 1 and RET indicating that GDNF stimulated calvarial osteoblasts via its canonical receptors. Finally, this study found that GDNF synergistically increased tumor necrosis factor-α (TNF-α)-stimulated MC3T3-E1 cell growth suggesting that GDNF interacted with TNF-α-induced signaling in osteoblastic cells. In conclusion, this study provides evidence for a direct, receptor-mediated effect of GDNF on osteoblasts highlighting a novel role for GDNF in bone physiology. \ud
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The binary near-Earth asteroid (175706) 1996 FG3 - An observational constraint on its orbital evolution
Using our photometric observations taken between 1996 and 2013 and other
published data, we derived properties of the binary near-Earth asteroid
(175706) 1996 FG3 including new measurements constraining evolution of the
mutual orbit with potential consequences for the entire binary asteroid
population. We also refined previously determined values of parameters of both
components, making 1996 FG3 one of the most well understood binary asteroid
systems. We determined the orbital vector with a substantially greater accuracy
than before and we also placed constraints on a stability of the orbit.
Specifically, the ecliptic longitude and latitude of the orbital pole are
266{\deg} and -83{\deg}, respectively, with the mean radius of the uncertainty
area of 4{\deg}, and the orbital period is 16.1508 +/- 0.0002 h (all quoted
uncertainties correspond to 3sigma). We looked for a quadratic drift of the
mean anomaly of the satellite and obtained a value of 0.04 +/- 0.20 deg/yr^2,
i.e., consistent with zero. The drift is substantially lower than predicted by
the pure binary YORP (BYORP) theory of McMahon and Scheeres (McMahon, J.,
Scheeres, D. [2010]. Icarus 209, 494-509) and it is consistent with the theory
of an equilibrium between BYORP and tidal torques for synchronous binary
asteroids as proposed by Jacobson and Scheeres (Jacobson, S.A., Scheeres, D.
[2011]. ApJ Letters, 736, L19). Based on the assumption of equilibrium, we
derived a ratio of the quality factor and tidal Love number of Q/k = 2.4 x 10^5
uncertain by a factor of five. We also derived a product of the rigidity and
quality factor of mu Q = 1.3 x 10^7 Pa using the theory that assumes an elastic
response of the asteroid material to the tidal forces. This very low value
indicates that the primary of 1996 FG3 is a 'rubble pile', and it also calls
for a re-thinking of the tidal energy dissipation in close asteroid binary
systems.Comment: Many changes based on referees comment
Derivation of some translation-invariant Lindblad equations for a quantum Brownian particle
We study the dynamics of a Brownian quantum particle hopping on an infinite
lattice with a spin degree of freedom. This particle is coupled to free boson
gases via a translation-invariant Hamiltonian which is linear in the creation
and annihilation operators of the bosons. We derive the time evolution of the
reduced density matrix of the particle in the van Hove limit in which we also
rescale the hopping rate. This corresponds to a situation in which both the
system-bath interactions and the hopping between neighboring sites are small
and they are effective on the same time scale. The reduced evolution is given
by a translation-invariant Lindblad master equation which is derived
explicitly.Comment: 28 pages, 4 figures, minor revisio
A Comparison of Maize Stalk Rot Occurrence in Bt and Non-Bt Hybrids
Stalk rots, caused by a complex of fungal species, are among the most widespread and destructive diseases of maize. Larvae of the European corn borer (ECB) (Ostrinia nubilalis) promote stalk rot development by creating entry points for fungi, serving as vectors of pathogens, and causing physiological stress that may predispose plants to stalk decay. Field experiments were conducted in 1998, 1999, and 2000 to determine whether the use of transgenic Bt hybrids expressing insecticidal proteins would influence stalk rot symptoms (pith disintegration, pith discoloration, and lodging). Five hybrids representing different Bt types (or “Bt events”) (176, BT11, MON810, DBT418, and CBH351) were paired with their near-isogenic, non-Bt counterparts and subjected to treatments of manual and natural infestation with ECB larvae. Manual infestation resulted in significantly more ECB tunneling than natural infestation in 1998 and 1999 and significantly more lodging in 1998. There were significant linear correlations between ECB injury and stalk rot symptoms in non-Bt hybrids in 1998 and 1999, but not in 2000. A standard foliar insecticide treatment for ECB did not significantly affect stalk rot symptoms. In 1998, Bt hybrids had significantly less ECB tunneling, stalk discoloration, pith disintegration, and lodging compared with non-Bt hybrids, but these effects depended upon the Bt event and the infestation treatment. Similar but less pronounced effects of Bt events were observed in 1999. The 2000 results were more variable; the amount of pith disintegration was significantly lower but discoloration was significantly higher in the BT11 hybrid compared with its non-Bt counterpart, and the amount of lodging was significantly higher in the event 176 hybrid compared with its non-Bt counterpart. The ratio of stalk strength to grain weight did not consistently differ between Bt and non-Bt hybrids. These results indicate that, although specific Bt events in some years may cause reductions in stalk rot, the overall effect of Bt transformation on stalk rot occurrence is highly variable
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