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Purpose: Inhibition of the protein kinase mammalian target of rapamycin (mTOR) is being evaluated for treatment of a variety of malignancies. However, the effects of mTOR inhibitors are cytostatic and standard size criteria do not reliably identify responding tumors. The aim of this study was to evaluate whether response to mTOR inhibition could be assessed by positron emission tomography (PET) imaging of tumor metabolism. Experiment Design: Glucose, thymidine, and amino acid utilization of human glioma cell lines with varying degrees of sensitivity to mTOR inhibition were assessed by measuring in vitro uptake of [18F]fluorodeoxyglucose ([18F]FDG), [18F]fluorothymidine ([18F]FLT), and [3H]l-tyrosine before and after treatment with the mTOR inhibitor rapamycin. The tumor metabolic activity in vivo was monitored by small-animal PET of tumor-bearing mice. The mechanisms underlying changes in metabolic activity were analyzed by measuring expression and functional activity of enzymes and transporters involved in the uptake of the studied imaging probes. Results: In sensitive cell lines, rapamycin decreased [18F]FDG and [18F]FLT uptake by up to 65% within 24 hours after the start of therapy. This was associated with inhibition of hexokinase and thymidine kinase 1. In contrast, [3H]l-tyrosine uptake was unaffected by rapamycin. The effects of rapamycin on glucose and thymidine metabolism could be imaged noninvasively by PET. In sensitive tumors, [18F]FDG and [18F]FLT uptake decreased within 48 hours by 56 ± 6% and 52 ± 8%, respectively, whereas there was no change in rapamycin-resistant tumors. Conclusions: These encouraging preclinical data warrant clinical trials evaluating [18F]FDG and [18F]FLT-PET for monitoring treatment with mTOR inhibitors in patients.

The objective of this study was to elucidate the mechanisms by which nebivolol, a cardio-selective beta-adrenergic receptor antagonist, inhibits rat aortic smooth muscle cell (RASMC) proliferation. Nebivolol was compared with DETA-NO and S-nitroso-N-acetylpenicillamine (SNAP), two nitric oxide (NO) donor agents, and alpha-difluoromethylornithine (DFMO), a known inhibitor of ornithine decarboxylase (ODC). All four test agents inhibited RASMC proliferation in a concentration-dependent manner, with nebivolol being the most potent (IC(50) = 4.5 microM), whereas atenolol, another relatively selective beta(1)-blocker, was inactive. DFMO, nebivolol, and DETA-NO interfered with cell proliferation in a cell-density-dependent manner, the lower the cell density the greater the inhibition of cell proliferation. The cytostatic effects of nebivolol and DETA-NO were completely independent of cyclic GMP, as neither ODQ (cytosolic guanylyl cyclase inhibitor) nor zaprinast (cyclic GMP phosphodiesterase inhibitor) affected the antiproliferative action of nebivolol or DETA-NO. The cytostatic effects of nebivolol, SNAP, and DFMO were largely prevented by the addition of excess putrescine, but not ornithine, to cell cultures. Moreover, nebivolol caused a marked reduction in the intracellular levels of putrescine, spermidine, and spermine. Like DFMO, nebivolol and DETA-NO interfered with the G(1)-phase to S-phase cell cycle transition in RASMC. These observations confirm previous findings that DFMO and NO interfere with RASMC proliferation by inhibiting ODC and polyamine production and provide evidence that nebivolol works by the same mechanism.

Semiconductor axial nanowire heterostructures are important for realizing the high-performance nano-photonics and opto-electronics devices. Although different IV and III-V semiconductor axial nanowire heterostructures have been successfully prepared in recent decade, few of them focused on the optical properties, such as the waveguide, due to their low light emission efficiencies. The II-VI semiconductor nanowires grown by chemical vapor deposition strategy, such as CdS, CdSe and their alloys, can act as nanoscale waveguide, nanolasers, etc., because of their high optical gains and atomically smooth surfaces. However, it is still a challenge to growing the high-quality II-VI semiconductor axial nanowire heterostructures, owning to the poor controllability of the vapor growth techniques. Here, the CdS/CdSSe axial nanowire heterostructures are prepared with well controlled CVD method under the catalysis of annealed Au nanoparticles. The scanning electron microscope characterization shows that the wires have smooth surfaces with Au particles at the tips, indicating the vapor-liquid-solid growth mechanism for the nanowire heterostructures. The microscope images of the dispersed wires illuminated with a 405 nm laser show that the red and the green segment align axially with a sharp interface, demonstrating the axial alignment of CdS and CdSSe segments. The position related micro-photoluminescence spectra exhibit near band edge emissions of CdS and CdSSe without obvious emission from defect states, which suggests that the wires have highly crystalline quality. The waveguide of the nanowire heterostructures is studied through respectively locally exciting the two ends of the wire with a focused 488 nm laser. The local illuminations at both the CdS end and the CdSSe end result in red emission at the corresponding remote ends of the wires, with the emission intensity of the former being one order lower than that of the later, which is caused by the reabsorption of the green light emission (from CdS segment) in the CdSSe segment. This indicates the asymmetric waveguide in these heterosturctures, which implies that the CdS/CdSSe nanowire heterostructures have the potential applications in the photodiode. Under the pumping of 470 nm femtosecond laser, dual-color (red and green) lasing is realized based on these wires, with the lasing threshold of red light lasing being lower than that of the green one, which results from the larger round-trip loss for the green light arising from the self-absorption in CdSSe segment. To prove that the light can be transfer between the two segments with different refractivities, the waveguide of the nanowire heterostructure is simulated by the COMSOL. The result shows that the light can effectively propagate between CdS and CdSSe segments, which ensures the light-matter interaction in the axial CdS/CdSSe nanowire heterostructures as discussed above. These high-quality CdS/CdSSe axial nanowire heterostructures can be found to have the potential applications in photodiodes, dual-color nanolasers and photodetectors.

Arginase, which exists as the isoforms arginase I and II, catalyzes the hydrolysis of arginine to ornithine and urea. Ornithine is the principal precursor for production of polyamines, which are required for cell proliferation. Rat aortic smooth muscle cells (RASMC) contain constitutive arginase I, and arginase inhibitors cause inhibition of cell proliferation. The objective of this study was to determine whether the elevated expression of arginase I in RASMC causes increased cell proliferation. RASMC were stably transfected with either rat arginase I cDNA or a β-galactosidase control expression plasmid. Western blots and arginase enzymatic assays revealed high-level expression of cytosolic arginase I in arginase I-transfected RASMC. Moreover, this observation was associated with the increased production of urea and polyamines and higher rates of RASMC proliferation. The two selective inhibitors of arginase, N G -hydroxy- l -arginine and S -(2-boronoethyl)- l -cysteine, inhibited arginase and decreased the production of urea and polyamines in arginase I-transfected RASMC, all of which were associated with the inhibition of cell proliferation. This study demonstrates that elevated arginase I expression increases RASMC proliferation by mechanisms involving increased production of polyamines. These observations suggest that arginase I plays a potentially important role in controlling RASMC proliferation.

The objectives of this study were to determine whether rat aortic smooth muscle cells (RASMC) express arginase and to elucidate the possible mechanisms involved in the regulation of arginase expression. The results show that RASMC contain basal arginase I (AI) activity, which is significantly enhanced by stimulating the cells with either interleukin (IL)-4 or IL-13, but arginase II (AII) expression was not detected under any condition studied here. We further investigated the signal transduction pathways responsible for AI induction. AI mRNA and protein levels were enhanced by addition of forskolin (1 μM) and inhibited by H-89 (30 μM), suggesting positive regulation of AI by a protein kinase A pathway. Genistein (10 μg/ml) and sodium orthovanadate (Na3VO4; 10 μM) were used to investigate the role of tyrosine phosphorylation in the control of AI expression. Genistein inhibited, whereas Na3VO4enhanced the induction of AI by IL-4 or IL-13. Along with immunoprecipitation and immunoblot analyses, these data implicate the JAK/STAT6 pathway in AI regulation. Dexamethasone (Dex) and interferon (IFN)-γ were investigated for their effects on AI induction. Dex (1 μM) and IFN-γ (100 U/ml) alone had no effect on basal AI expression in RASMC, but both reduced AI induction by IL-4 and IL-13. In combination, Dex and IFN-γ abolished AI induction by IL-4 and IL-13. Finally, both IL-4 and IL-13 significantly increased RASMC DNA synthesis as monitored by [3H]thymidine incorporation, demonstrating that upregulation of AI is correlated with an increase in cell proliferation. Blockade of AI induction by IFN-γ, H-89, or genistein also blocked the increase in cell proliferation. These observations are consistent with the possibility that upregulation of AI might play an important role in the pathophysiology of vascular disorders characterized by excessive smooth muscle growth.

The objective of this study was to elucidate the mechanism by which cyclic AMP increases arginase activity in cultured human Caco-2 tumor cells. Caco-2 cells were incubated for 24 h in the presence of 8-bromo cyclic AMP or forskolin, and the cells were harvested, lysed, and assayed for total arginase activity. Both test agents increased arginase activity by twofold, and this was attributed to the induction of the arginase II isoform. Both arginase II mRNA and protein showed increased expression in response to 8-bromo cyclic AMP and forskolin, and these effects were inhibited by H-89 (protein kinase A inhibitor), enhanced by okadaic acid (phosphatase inhibitor), and enhanced by 1-methyl-3-isobutylxanthine (cyclic nucleotide phosphodiesterase inhibitor). Cyclic GMP did not appear to be involved in arginase II induction. These observations indicate that cyclic AMP stimulates arginase II gene expression by mechanisms involving activation of protein kinase A and consequent activation of appropriate transcription factors.

In an attempt to identify potent inhibitors of inducible (type II) NO synthase (iNOS) for use in cell culture systems, we found that two S-substituted isothioureas were very potent in cell culture but one such compound also interfered with the induction of NO synthase. S-Ethylisothiourea (EITU) and S-aminoethylisothiourea (AEITU) were found to be much more potent than NG-methylarginine, NG-nitroarginine methy lester, or aminoguanidine as inhibitors of NO production by cultured RAW 264.7 cell macrophages activated by lipopolysaccharide (LPS). The approximate EC50 values as inhibitors of NO production, assessed by 24-h accumulation in cell culture media, were 10 microM (EITU), 30 microM (AEITU), 300 microM (NG-methylarginine), and 1000 microM (aminoguanidine). EITU was found to inhibit NO production by activated macrophages without interfering with the induction of iNOS. More specifically, EITU failed to influence transcription of iNOS mRNA (Northern blot analysis), translation of iNOS protein (pulse experiments), or degradation of translated iNOS protein (pulse-chase experiments). In contrast, however, AEITU interfered markedly with the induction of iNOS by mechanisms attributed to inhibition of translation of iNOS mRNA into functional protein as well as acceleration of degradation of already translated iNOS protein. These observations indicate that AEITU should not be used in cell culture experiments where the intent is solely to assess the consequences of inhibition of iNOS catalytic activity.

In the paper, an determinant approach of divergence was provided based on the research of stability of unscented Kalman filter(UKF). The criterion and determinant method of filter divergence based on the definition of stability were brought forward. The divergence of the filter can be confirmed based on the 3 determinant conditions. It is a determinant method based on the whole filter process. It not only conquers the disadvantage of sensitive to outlier, but also improves the ability of resist outlier. It is benefit to decrease the misjudging risk and to enhance the reliability and veracity. The results of simulation indicate the veracity and validity of the method.

According to local information of images, region- based image retrieval is the focus of recent research works, as the approaches based global features can not achieve the expectation querying results. The objects of interest generally occupy only one small part of images, so the image segmentation with different object regions must be conducted for the region-based image retrieval schemes. However, accurate object segmentation is still beyond current computer vision technique. Here, we proposed one feasible image retrieval scheme based the hierarchical uniform segmentations, which avoid the complexity of image segmentations. Firstly, the querying image is segmented into equal blocks at different hierarchical levels, and the more blocks with larger hierarchical levels. Then, according to the similar metrics of these different size blocks to the expectation image into segmentations, the images containing querying objects can be retrieved with information about scales and locations of query objects in retrieved images. Finally, the proposed image retrieval schemes are tested by experiments via database with 500 images, and the retrieval accuracy can achieve 78% for the optimal similar metric threshold, and is comparable to that of region-based schemes.

The users' retrieval words are distinguished, judged, and classified by utilizing the intelligence character of agent, and the concept of topic derivation is introduced. Some subtopics, which are derived from the known topic, are submitted to the Agent for searching, therefore, the retrieval results could be classified according to the topics and be convenient for user to choose. The test demonstrates that in combination the fixed topic and the topics we recommend, the knowledge warehouse is enriched for perfecting the procedure of topicderivation, the retrieval range is narrowed and the local memory is reduced.

Postoperative myocardial global dysfunction causes mortality and morbidity in cyanotic congenital defects. This study investigates whether leukocyte depletion during coronary perfusion following reoxygenation can maintain endothelial and myocyte function, or less oxidant damage in a porcine neonatal model. After 30 minutes hypoxemia, 13 piglets underwent 60 minutes reoxygenation. The aorta was clamped and coronary reperfusion was either with normal blood (N=6), or leukocyte free blood by an inline filter (N=7). Cardiac function and endothelial response were assessed before and after cardiopulmonary bypass (CPB). Contractile recovery was improved by leukocyte depletion. Additionally, the antioxidant reserve capacity reserved more (534 36 versus 772 91; p0.05) than reoxygenation without a leukocyte-depleting filter. Leukocyte depletion returned more extreme relaxation to acetylcholine (71.8 20.4% versus 41.2 9.8%; p0.05), but did not change the endothelium-independent relaxation to sodium nitroprusside in either group. Activated leukocytes release oxygen free radicals that play a role in deterioration of the endothelial/myocardial function after reoxygenation and this deterioration in cyanotic heart diseases may be avoided by the use of the leukocyte-depleting filter.

The objective of this study was to elucidate the role and mechanism of nitric oxide (NO) synthase (NOS) in modulating the growth of the Caco-2 human colon carcinoma cell line. The two novel observations reported here are, first, that NG-hydroxy-l-arginine (NOHA) inhibits Caco-2 tumor cell proliferation, likely by inhibiting arginase activity, and, second, that NO causes cytostasis by mechanisms that might involve inhibition of ornithine decarboxylase (ODC) activity. Both arginase and ODC are enzymes involved in the conversion of arginine to polyamines required for cell proliferation. Cell growth was monitored by cell count, cell protein analysis, and DNA synthesis. NOHA (1–30 μM) and NO in the form of DETA/NO (1–30 μM) inhibited cell proliferation by 30–85%. The cytostatic effect of NOHA was prevented by addition of excess ornithine, putrescine, spermidine, or spermine to cell cultures, whereas the cytostatic effect of NO (DETA/NO) and α-difluoromethylornithine (ODC inhibitor) was unaffected by ornithine but was prevented by putrescine, spermidine, or spermine. The cytostatic effect of NOHA appeared to be independent of its conversion to NO, and the effect of NO appeared to be independent of cGMP. NOHA inhibited urea production by Caco-2 cells and inhibited arginase catalytic activity (85% at 3 μM), whereas NO (DEA/NO and SNAP) inhibited ODC activity (≥60% at 30 μM) without affecting arginase activity. Coculture of Caco-2 cells with lipopolysaccharide/cytokine-activated rat aortic endothelial cells markedly slowed Caco-2 cell proliferation, and this was blocked by NOS inhibitors. These observations that NOHA and NO may inhibit sequential steps in the arginine-polyamine pathway suggest a novel biological role for NOS in the inhibition of cell proliferation of certain tumor cells and possibly other cell types.