المؤلفون: Libo Xing, Muhammad Azher Nawaz, Jiangping Mao, Muhammad Mobeen Tahir, Shaohuan Li, Xiaoyun Zhang, Dong Zhang, Ke Li, Jianxin Niu, Yu Liu

المصدر: Physiologia Plantarum. 173:867-882

مصطلحات موضوعية: 0106 biological sciences, 0301 basic medicine, Physiology, Vegetative reproduction, Endogeny, Plant Science, Biology, Plant Roots, 01 natural sciences, Transcriptome, 03 medical and health sciences, chemistry.chemical_compound, Cutting, Nitrate, Downregulation and upregulation, Gene Expression Regulation, Plant, Botany, Genetics, Gene, Nitrates, Gene Expression Profiling, Cell Biology, General Medicine, 030104 developmental biology, chemistry, Malus, Rootstock, 010606 plant biology & botany

الوصف: In the process of vegetative propagation of apple rootstocks, the development of adventitious roots (ARs) has crucial importance. Nitrate is an essential nutrient necessary for plant growth; however, the inhibitory effect of high nitrate on ARs formation has not been explored. The physiological and molecular mechanisms underlying ARs inhibition were examined in this study. Stem cuttings of B9 apple rootstock were cultured on two nitrate treatments (T1 = 18.7 mM L-1 and T2 = 37.5 mM L-1 ), where T2 was identified as ARs inhibiting treatment. Morphological and anatomical observations advocating that high availability of nitrate inhibited AR formation by delaying the ARs initiation and emergence stages, where the root number was 287%, and the length was 604.6% lower than the T1 cuttings. Moreover, the contents of endogenous hormones were also elevated in response to T2 at most of the time points, which may cause a hormonal imbalance within the plant body and drive toward ARs inhibition. Furthermore, 3686 genes were differentially expressed by high-throughput sequencing. Out of these, 1797 genes were upregulated, and 1889 genes were downregulated. Approximately 238 genes related to nitrate, hormones, root development, and cell-cycle induction pathways were selected according to their potential to be involved in ARs regulation. This is the first study providing information regarding the inhibitory effect of high nitrate on ARs formation in apple rootstock.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::32ab6c1c1fba18a69e8f9239ee6a171aTest
https://doi.org/10.1111/ppl.13480Test

المؤلفون: Ling Qiu, Dong Xu, Hang Li, Qingzhu Liu, Ke Li, Ying Peng, Jianguo Lin

المصدر: Cell Biology International. 45:1015-1029

مصطلحات موضوعية: Male, 0301 basic medicine, Cell Survival, MAP Kinase Signaling System, Osteoclasts, Bone Marrow Cells, Zoledronic Acid, Mice, 03 medical and health sciences, 0302 clinical medicine, Prenylation, Downregulation and upregulation, Osteogenesis, Osteoclast, medicine, Animals, Viability assay, Phosphorylation, Protein kinase B, Mice, Inbred ICR, Diphosphonates, NFATC Transcription Factors, biology, Chemistry, Macrophages, RANK Ligand, NF-kappa B, Cell Differentiation, Cell Biology, General Medicine, 030104 developmental biology, medicine.anatomical_structure, RANKL, Apoptosis, 030220 oncology & carcinogenesis, biology.protein, Cancer research, Mevalonate pathway, Mitogen-Activated Protein Kinases, Proto-Oncogene Proteins c-akt, Signal Transduction

الوصف: Bisphosphonates (BPs), especially zoledronic acid (ZOL), are clinically used to treat osteolytic bone lesions. However, serious side-effects may be also induced during the therapeutic process. To improve the BPs drugs, here, we investigated the effects of a series of ZOL derivatives with increasing number of methylene linker between the imidazole ring and the P-C-P backbone named IPrDP, IBDP, IPeDP, and IHDP on cell viability and receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclast differentiation, function and apoptosis induction in mouse bone marrow-derived macrophages (BMMs). Our results suggested that IPeDP and IHDP, which contains 4 and 5 methylene linkers, respectively, exerted lower toxicity on BMMs compared with ZOL, IPrDP, and IBDP, which contains 1, 2, and 3 methylene linkers respectively. At concentrations below cytotoxicity threshold, IPeDP and IHDP possessed strong abilities of antiosteoclast formation, antibone absorption, and inducing osteoclast apoptosis, which were similar to ZOL and more powerful than IPrDP and IBDP. The mechanism behind these effects of IPeDP and IHDP might involve the interference of small GTPases prenylation through suppression of mevalonate pathway. The downregulation of JNK and Akt phosphorylation and subsequent inhibition of the expression of c-Fos and NFATc1 might also be involved. Our results supported the potential usage of IPeDP and IHDP to treat bone-related disorders involving increased osteoclastogenesis. Our attempt to extend the methylene linker between the imidazole ring and the P-C-P backbone of ZOL also reveals some regularities between the structure and properties of the BPs drugs.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::caf0a5e94d6ec2e16e83ad8693a21bbcTest
https://doi.org/10.1002/cbin.11546Test

المؤلفون: Shen Ren, Xing-Yue Xu, Jun-nan Hu, Ke-Ke Li, Ying Liu, Wei Li, Shuang Jiang, Zhi Liu, Xiao-jie Gong, Ying-Ping Wang

المصدر: Kaohsiung Journal of Medical Sciences, Vol 36, Iss 9, Pp 732-740 (2020)

مصطلحات موضوعية: Ginsenosides, NF-E2-Related Factor 2, HEK‐293, Panax, cisplatin, Antineoplastic Agents, Pharmacology, Antioxidants, Nephrotoxicity, Lipid peroxidation, 03 medical and health sciences, Ginseng, chemistry.chemical_compound, 0302 clinical medicine, Malondialdehyde, medicine, Humans, Viability assay, bcl-2-Associated X Protein, Cisplatin, lcsh:R5-920, Caspase 3, business.industry, nephrotoxicity, anti‐apoptosis, General Medicine, Glutathione, Caspase 9, Oxidative Stress, HEK293 Cells, Gene Expression Regulation, Proto-Oncogene Proteins c-bcl-2, chemistry, Ginsenoside, 030220 oncology & carcinogenesis, 030211 gastroenterology & hepatology, Reactive Oxygen Species, business, lcsh:Medicine (General), ginsenoside Rk1, Heme Oxygenase-1, Signal Transduction, medicine.drug

الوصف: Cisplatin, as one of the most effective chemotherapeutic agents, its clinical use is limited by serious side effect of nephrotoxicity. Cisplatin‐induced nephrotoxicity is closely related to apoptosis induction and activation of caspase. The present study aimed to explore the potential protective effect of ginsenoside Rk1 (Rk1), a rare ginsenoside generated during steaming ginseng, on cisplatin‐induced nephrotoxicity and the underlying mechanisms in human embryonic kidney 293 (HEK‐293) cells. Our results showed that the reduced cell viability induced by cisplatin could significantly recover by Rk1. Furthermore, glutathione (GSH) as an oxidative index, was elevated and the lipid peroxidation product malondialdehyde (MDA) was significantly decreased after Rk1 treatment compared to the cisplatin group. Additionally, Rk1 can also decrease the ROS fluorescence expression and increase the protein levels of nuclear factor erythroid 2‐related factor 2 (Nrf2) and heme oxygenase‐1 (HO‐1) compared to the cisplatin group, which suggested a suppression of oxidative response. More importantly, the cisplatin‐induced elevated protein levels of Bax, cleaved caspase‐3, cleaved caspase‐9, and decreased protein level of Bcl‐2 were reversed after treatment with Rk1. Our results elucidated the possible protective mechanism of Rk1 for the first time, which may involve in its anti‐oxidation and anti‐apoptosis effects.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::c4faa5b37390f574372dbb20697fb6b0Test
https://doaj.org/article/85cbfe6cd9d64f929e81247089cf13eaTest

المؤلفون: Ran Zhang, Amy M. Fowler, Guang-Hong Chen, Lee G. Wilke, John Garrett, Ke Li, Frederick Kelcz

المصدر: Med Phys

مصطلحات موضوعية: Digital mammography, Computer science, Breast imaging, medicine.medical_treatment, Breast Neoplasms, Article, Imaging phantom, 030218 nuclear medicine & medical imaging, 03 medical and health sciences, 0302 clinical medicine, Data acquisition, medicine, Animals, Humans, Mammography, Computer vision, Image resolution, Mastectomy, medicine.diagnostic_test, Phantoms, Imaging, business.industry, X-Rays, X-ray, General Medicine, Digital Breast Tomosynthesis, Radiography, 030220 oncology & carcinogenesis, X-Ray Phase-Contrast Imaging, Cattle, Artificial intelligence, business, Phase retrieval

الوصف: PURPOSE: A major technical obstacle to bringing x-ray multicontrast (i.e., attenuation, phase, and dark-field) imaging methodology to clinical use is the prolonged data acquisition time caused by the phase stepping procedure. The purpose of this work was to introduce a fast acquisition with seamless stage translation (FASST) technique to a prototype multicontrast breast imaging system for reduced image acquisition time that is clinically acceptable. METHODS: The prototype system was constructed based on a Hologic full-field digital mammography + digital breast tomosynthesis combination system. During each FASST acquisition process, a motorized stage holding a diffraction grating travels continuously with a constant velocity, and a train of 15 short x-ray pulses (35 ms each) was delivered by using the Zero-Degree Tomo mode of the Hologic system. Standard phase retrieval was applied to the 15 subimages without spatial interpolation to avoid spatial resolution loss. The method was evaluated using a physical phantom, a bovine udder specimen, and a freshly resected mastectomy specimen. The FASST technique was experimentally compared with single-shot acquisition methods and the standard phase stepping method. RESULTS: The image acquisition time of the proposed method is 3.7 s. In comparison, conventional phase stepping took 105 s using the same prototype imaging system. The mean glandular dose of both methods was matched at 1.3 mGy. No artifacts or spatial resolution loss was observed in images produced by FASST. In contrast, the single-shot methods led to spatial resolution loss and residual moiré artifacts. CONCLUSIONS: The FASST technique reduces the data acquisition time of the prototype multicontrast x-ray breast imaging system to 3.7 s, such that it is comparable to a clinical digital breast tomosynthesis exam.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::310aad6b367519160bea8cd3594eb59dTest
https://doi.org/10.1002/mp.14297Test

المؤلفون: Charles M. Strother, Ke Li, Guang-Hong Chen

المصدر: Med Phys

مصطلحات موضوعية: Image quality, Computer science, Perfusion Imaging, Statistics as Topic, Perfusion scanning, Computed tomography, Signal-To-Noise Ratio, Signal, Article, 030218 nuclear medicine & medical imaging, 03 medical and health sciences, Dogs, 0302 clinical medicine, Image Processing, Computer-Assisted, medicine, Animals, Cerebral Blood Volume, Humans, medicine.diagnostic_test, Noise (signal processing), Radiation dose, Brain, Statistical model, General Medicine, Variance (accounting), Cerebrovascular Circulation, 030220 oncology & carcinogenesis, Computer Science::Programming Languages, Tomography, X-Ray Computed, Algorithm

الوصف: PURPOSE: The development and clinical employment of a computed tomography (CT) imaging system benefit from a thorough understanding of the statistical properties of the output images; cerebral CT perfusion (CTP) imaging system is no exception. A series of articles will present statistical properties of CTP systems and the dependence of these properties on system parameters. This Part I paper focuses on the signal and noise properties of cerebral blood volume (CBV) maps calculated using a nondeconvolution-based method. METHODS: The CBV imaging chain was decomposed into a cascade of subimaging stages, which facilitated the derivation of analytical models for the probability density function, mean value, and noise variance of CBV. These models directly take CTP source image acquisition, reconstruction, and postprocessing parameters as inputs. Both numerical simulations and in vivo canine experiments were performed to validate these models. RESULTS: The noise variance of CBV is linearly related to the noise variance of source images and is strongly influenced by the noise variance of the baseline images. Uniformly partitioning the total radiation dose budget across all time frames was found to be suboptimal, and an optimal dose partition method was derived to minimize CBV noise. Results of the numerical simulation and animal studies validated the derived statistical properties of CBV. CONCLUSIONS: The statistical properties of CBV imaging systems can be accurately modeled by extending the linear CT systems theory. Based on the statistical model, several key signal and noise characteristics of CBV were identified and an optimal dose partition method was developed to improve the image quality of CBV.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::92a4a7c65fd618d2ad2563ff601781f0Test
https://doi.org/10.1002/mp.13806Test

المؤلفون: Chun-Yu He, Ying Liu, Ke Li, Sining Shen, Hao-Rang Wang, Cheng-Liang Yang

المصدر: Molecular Oncology. 13:2554-2573

مصطلحات موضوعية: 0301 basic medicine, Cancer Research, Cell migration, General Medicine, Biology, medicine.disease_cause, Long non-coding RNA, PVT1, Gene expression profiling, 03 medical and health sciences, 030104 developmental biology, 0302 clinical medicine, Oncology, 030220 oncology & carcinogenesis, microRNA, Genetics, medicine, Cancer research, Molecular Medicine, Gene silencing, Viability assay, Carcinogenesis

الوصف: Accumulating evidence has established that long noncoding RNA (lncRNA) plasmacytoma variant translocation 1 (PVT1) is a tumor regulator in many cancers. Here, we aimed to investigate the possible function of lncRNA PVT1 in esophageal carcinoma (EC) via targeting of microRNA-145 (miR-145). Initially, microarray-based gene expression profiling of EC was employed to identify differentially expressed genes. Moreover, the expression of lncRNA PVT1 was examined and the cell line presenting with the highest level of lncRNA PVT1 expression was selected for subsequent experiments. We then proceeded to examine interaction among lncRNA PVT1, FSCN1, and miR-145. The effect of lncRNA PVT1 on viability, migration, invasion, apoptosis, and tumorigenesis of transfected cells was examined with gain-of-function and loss-of-function experiments. We observed that lncRNA PVT1 was robustly induced in EC. lncRNA PVT1 could bind to miR-145 and regulate its expression, and FSCN1 is a target gene of miR-145. Overexpression of miR-145 or silencing of lncRNA PVT1 was revealed to suppress cell viability, migration, and invasion abilities, while also stimulating cell apoptosis. Furthermore, our in vivo results showed that overexpression of miR-145 or silencing of lncRNA PVT1 resulted in decreased tumor growth in nude mice. In conclusion, our research reveals that down-regulation of lncRNA PVT1 could potentially promote expression of miR-145 to repress cell migration and invasion, and promote cell apoptosis through the inhibition of FSCN1. This highlights the potential of lncRNA PVT1 as a therapeutic target for EC treatment.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::aa8e81789047d7bd6df3778eb925d9cfTest
https://doi.org/10.1002/1878-0261.12555Test

المؤلفون: Qiang Wang, Ke Li, Kenneth Puterbaugh, Stefan Siegel, Jianyong Jiang, J. Young, Yuan-Chuan Tai, Joseph A. O'Sullivan

المصدر: Med Phys

مصطلحات موضوعية: Scanner, Materials science, medicine.diagnostic_test, Detector, Contrast Media, General Medicine, Torso, Article, Imaging phantom, Lyso, 030218 nuclear medicine & medical imaging, 03 medical and health sciences, 0302 clinical medicine, medicine.anatomical_structure, Positron emission tomography, Positron Emission Tomography Computed Tomography, 030220 oncology & carcinogenesis, Image Processing, Computer-Assisted, medicine, Whole Body Imaging, Pinhole (optics), Monte Carlo Method, Sensitivity (electronics), Biomedical engineering

الوصف: Purpose We have developed a second-generation virtual-pinhole (VP) positron emission tomography (PET) device that can position a flat-panel PET detector around a patient's body using a robotic arm to enhance the contrast recovery coefficient (CRC) and detectability of lesions in any region-of-interest using a whole-body PET/computed tomography (CT) scanner. Methods We constructed a flat-panel VP-PET device using 32 high-resolution detectors, each containing a 4 × 4 MPPC array and 16 × 16 LYSO crystals of 1.0 × 1.0 × 3.0 mm3 each. The flat-panel detectors can be positioned around a patient's body anywhere in the imaging field-of-view (FOV) of a Siemens Biograph 40 PET/CT scanner by a robotic arm. New hardware, firmware and software have been developed to support the additional detector signals without compromising a scanner's native functions. We stepped a 22 Na point source across the axial FOV of the scanner to measure the sensitivity profile of the VP-PET device. We also recorded the coincidence events measured by the scanner detectors and by the VP-PET detectors when imaging phantoms of different sizes. To assess the improvement in the CRC of small lesions, we imaged an elliptical torso phantom measuring 316 × 228 × 162 mm3 that contains spherical tumors with diameters ranging from 3.3 to 11.4 mm with and without the VP-PET device. Images were reconstructed using a list mode Maximum-Likelihood Estimation-Maximization algorithm implemented on multiple graphics processing units (GPUs) to support the unconventional geometries enabled by a VP-PET system. The mean and standard deviation of the CRC were calculated for tumors of different sizes. Monte Carlo simulation was also conducted to image clusters of lesions in a torso phantom using a PET/CT scanner alone or the same scanner equipped with VP-PET devices. Receiver operating characteristic (ROC) curves were analyzed for three system configurations to evaluate the improvement in lesion detectability by the VP-PET device over the native PET/CT scanner. Results The repeatability in positioning the flat-panel detectors using a robotic arm is better than 0.15 mm in all three directions. Experimental results show that the average CRC of 3.3, 4.3, and 6.0 mm diameter tumors was 0.82%, 2.90%, and 5.25%, respectively, when measured by the native scanner. The corresponding CRC was 2.73%, 6.21% and 10.13% when imaged by the VP-PET insert device with the flat-panel detector under the torso phantom. These values may be further improved to 4.31%, 9.65% and 18.01% by a future dual-panel VP-PET insert device if DOI detectors are employed to triple its detector efficiency. Monte Carlo simulation results show that the tumor detectability can be improved by a VP-PET device that has a single flat-panel detector. The improvement is greater if the VP-PET device employs a dual-panel design. Conclusions We have developed a prototype flat-panel VP-PET device and integrated it with a clinical PET/CT scanner. It significantly enhances the contrast of lesions, especially for those that are borderline detectable by the native scanner, within regions-of-interest specified by users. Simulation demonstrated the enhancement in lesion detectability with the VP-PET device. This technology may become a cost-effective solution for organ-specific imaging tasks.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::aece3d569e02c32d3c231de9d0e69ba1Test
https://doi.org/10.1002/mp.13724Test

المؤلفون: John Hayes, Ke Li, Ran Zhang, Juan P. Cruz-Bastida, Guang-Hong Chen, Daniel Gomez-Cardona

المصدر: Medical Physics. 46:3013-3024

مصطلحات موضوعية: Quality Control, Image quality, Computer science, Anisotropic diffusion, Noise reduction, Gaussian, Signal-To-Noise Ratio, Imaging phantom, 030218 nuclear medicine & medical imaging, law.invention, 03 medical and health sciences, symbols.namesake, 0302 clinical medicine, law, Hounsfield scale, Humans, Image resolution, Filtration, Phantoms, Imaging, Truncated mean, General Medicine, Radiographic Image Enhancement, Noise, 030220 oncology & carcinogenesis, symbols, Tomography, X-Ray Computed, Algorithm

الوصف: Purpose In previous works, it has been demonstrated that for filtered backprojection (FBP) reconstruction-based computed tomography (CT) images, the measured CT numbers are biased and the bias level decreases with increasing radiation dose. Low-dose scans typically include noise reduction schemes to reduce noise level. The purpose of this work was to investigate the potential impact of different noise reduction schemes on the CT number bias. Methods Three different filtration methods: Gaussian, adaptive trimmed mean (ATM), and anisotropic diffusion (AD) were implemented to reduce noise. All filters were independently applied in three different domains: raw counts, log-processed sinogram, or reconstructed image domain. A quality assurance phantom was scanned on a benchtop CT cone beam CT system, at dose levels ranging from 0.6 to 4.0 mGy. The conventional FBP reconstructions were performed to reconstruct CT images for the study of CT number biases. The CT number bias of different material inserts in the phantom was then measured. To further study the overall impact of CT number bias together with the potential consequences of noise reduction schemes on both the spatial resolution and noise characteristics, the task-based detectability of a high-contrast and high spatial resolution imaging task was used as an example to assess the performance of each noise reduction scheme. To qualitatively assess the impact of these noise reduction schemes on image, an anthropomorphic head phantom was also scanned on the benchtop CT system and processed with the above noise reduction schemes to generate images for demonstration. Results Our results demonstrated the following major findings: (a) CT number bias can be significantly reduced when the noise reduction schemes are implemented in the raw counts domain; CT number bias cannot be reduced when these noise reduction schemes are implemented either in the reconstructed image domain or in the log-processed sinogram domain. (b) The extent of CT number bias reduction is dependent on both the material composition and noise reduction parameters. (c) The overall impact of the noise reduction schemes can be studied using the task-based detectability analysis framework and this framework can be used to select the appropriate parameters in each noise reduction scheme to optimize the performance for a given imaging task. Conclusions Noise reduction schemes can be used to considerably reduce CT number bias when they are implemented in the raw counts domain; however, their application cannot be arbitrarily extended to either the log-processed sinogram data domain or image domain. Trade-offs between bias reduction and overall image quality must be studied for an optimal performance of a given imaging task.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::c746e6848d2c5d951ca2d7a8a2fc7289Test
https://doi.org/10.1002/mp.13549Test

المؤلفون: Joseph A. O'Sullivan, Yuan-Chuan Tai, Jianyong Jiang, Ke Li, Sergey Komarov

المصدر: Medical Physics. 46:1798-1813

مصطلحات موضوعية: Physics, Photomultiplier, business.industry, Image quality, Detector, General Medicine, Iterative reconstruction, Lyso, Imaging phantom, 030218 nuclear medicine & medical imaging, 03 medical and health sciences, 0302 clinical medicine, Optics, Sampling (signal processing), 030220 oncology & carcinogenesis, Front panel, business

الوصف: Purpose We investigated the feasibility of a novel positron emission tomography (PET) system that provides near real-time feedback to an operator who can interactively scan a patient to optimize image quality. The system should be compact and mobile to support point-of-care (POC) molecular imaging applications. In this study, we present the key technologies required and discuss the potential benefits of such new capability. Methods The core of this novel PET technology includes trackable PET detectors and a fully three-dimensional, fast image reconstruction engine implemented on multiple graphics processing units (GPUs) to support dynamically changing geometry by calculating the system matrix on-the-fly using a tube-of-response approach. With near real-time image reconstruction capability, a POC-PET system may comprise a maneuverable front PET detector and a second detector panel which can be stationary or moved synchronously with the front detector such that both panels face the region-of-interest (ROI) with the detector trajectory contoured around a patient's body. We built a proof-of-concept prototype using two planar detectors each consisting of a photomultiplier tube (PMT) optically coupled to an array of 48 × 48 lutetium-yttrium oxyorthosilicate (LYSO) crystals (1.0 × 1.0 × 10.0 mm3 each). Only 38 × 38 crystals in each arrays can be clearly re-solved and used for coincidence detection. One detector was mounted to a robotic arm which can position it at arbitrary locations, and the other detector was mounted on a rotational stage. A cylindrical phantom (102 mm in diameter, 150 mm long) with nine spherical lesions (8:1 tumor-to-background activity concentration ratio) was imaged from 27 sampling angles. List-mode events were reconstructed to form images without or with time-of-flight (TOF) information. We conducted two Monte Carlo simulations using two POC-PET systems. The first one uses the same phantom and detector setup as our experiment, with the detector coincidence re-solving time (CRT) ranging from 100 to 700 ps full-width-at-half-maximum (FWHM). The second study simulates a body-size phantom (316 × 228 × 160 mm3 ) imaged by a larger POC-PET system that has 4 × 6 modules (32 × 32 LYSO crystals/module, four in axial and six in transaxial directions) in the front panel and 3 × 8 modules (16 × 16 LYSO crystals/module, three in axial and eight in transaxial directions) in the back panel. We also evaluated an interactive scanning strategy by progressively increasing the number of data sets used for image reconstruction. The updated images were analyzed based on the number of data sets and the detector CRT. Results The proof-of-concept prototype re-solves most of the spherical lesions despite a limited number of coincidence events and incomplete sampling. TOF information reduces artifacts in the reconstructed images. Systems with better timing resolution exhibit improved image quality and reduced artifacts. We observed a reconstruction speed of 0.96 × 106 events/s/iteration for 600 × 600 × 224 voxel rectilinear space using four GPUs. A POC-PET system with significantly higher sensitivity can interactively image a body-size object from four angles in less than 7 min. Conclusions We have developed GPU-based fast image reconstruction capability to support a PET system with arbitrary and dynamically changing geometry. Using TOF PET detectors, we demonstrated the feasibility of a PET system that can provide timely visual feedback to an operator who can scan a patient interactively to support POC imaging applications.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::e1e30efe8b1e9040580dcc0fd09dbb77Test
https://doi.org/10.1002/mp.13397Test

المؤلفون: Ke Li, Mingyu Han, Yuan Meng, Hui Wang, Jiangping Mao, Dong Zhang

المصدر: Physiologia Plantarum. 166:663-676

مصطلحات موضوعية: 0106 biological sciences, 0301 basic medicine, Cytokinins, Physiology, Endogeny, Plant Science, Plant Roots, 01 natural sciences, 03 medical and health sciences, chemistry.chemical_compound, Cutting, Auxin, Genetics, Primordium, Abscisic acid, chemistry.chemical_classification, Indoleacetic Acids, Chemistry, fungi, food and beverages, Cell Biology, General Medicine, Cell cycle, Cell biology, 030104 developmental biology, Malus, Cytokinin, Rootstock, Abscisic Acid, 010606 plant biology & botany

الوصف: Cytokinin (CK) inhibits adventitious root (AR) formation in stem cuttings. Little is known, however, about the mechanism underlying the inhibitory effect. In this study, 2 mg l-1 of exogenous 6-benzyl adenine (6-BA) was administered to 3 and 7-day-old apple rootstocks 'M.26' cuttings (3 and 7 days 6-BA) by transferring them from a rooting medium containing indole-3-butanoic acid to the medium containing 6-BA. Anatomical and morphological observations revealed that the exogenous application of 6-BA inhibited primordia formation in the 3 days 6-BA but not the 7 days 6-BA group. The concentration of auxin (IAA), the ratios of IAA/CK and IAA/abscisic acid were lower in 3 days 6-BA than in 7 days 6-BA. Expression analysis of genes known to be associated with AR formation was also analyzed. In the 3 days 6-BA group, high level of CK inhibited the synthesis and transport of auxin, as a result, low endogenous auxin level suppressed the auxin signaling pathway genes, as were other AR development and cell cycle related genes; all of which had an inhibitory impact on AR primordium formation. On the contrary, low CK level in the 7 days 6-BA, reduced the inhibitory impact on auxin levels, leading to an upregulated expression of genes known to promote AR primordia formation. Collectively, our data indicated that 3-7 days is the time period in which AR primordia formation occurs in cuttings of 'M.26' and that the inhibition of AR development by CK is due to the suppression of AR primordia development over 3-7 days period after culturing in rooting medium.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::ff69a2fb7cb1ce7767e2526a0960cc35Test
https://doi.org/10.1111/ppl.12817Test