BDS Dual-Frequency Carrier Phase Multipath Hemispherical Map Model and Its Application in Real-Time Deformation Monitoring.

The BDS multipath delay error is highly related to the surrounding monitoring environment, which cannot be eliminated or mitigated by applying the double difference observation model. In the actual monitoring environment, due to the complexity of the BDS constellation, it is difficult for existing algorithms to consider GEO, IGSO, MEO and other different orbital types of satellites for real-time and efficient multipath error reduction. Therefore, we propose a novel BDS dual-frequency multipath error reduction method for real deformation monitoring for BDS considering various satellite orbit types. This method extracts the single error residual of each satellite based on the assumption of "zero mean" and divides the appropriate grid density of GEO and IGSO/MEO, respectively, to construct a dual-frequency multipath hemispherical map model suitable for BDS satellites with different orbital types. This method can realize the multipath error elimination of the observed values of different orbits and different frequencies. The results of simulation experiments and real deformation monitoring data demonstrate that this method can effectively eliminate low-frequency multipath delay errors in the observation domain and coordinate domain. After multipath correction, the precision of the horizontal coordinates and height coordinates are 1.7 mm and 4.6 mm. The precision of the horizontal coordinate and height coordinate is increased by 50% and 60%, respectively. The fixed rate of ambiguity increased by 5-7%.

Radioprotective effect of X-ray abdominal FLASH irradiation: Adaptation to oxidative damage and inflammatory response may be benefiting factors.

BACKGROUND: Ultrahigh dose-rate irradiation (FLASH-IR) was reported to be efficient in tumor control while reducing normal tissue radiotoxicity. However, the mechanism of such phenomenon is still unclear. Besides, the FLASH experiments using high energy X-ray, the most common modality in clinical radiotherapy, are rarely reported. This study aims to investigate the radiobiological response using 6 MV X-ray FLASH-IR or conventional dose-rate IR (CONV-IR). METHODS: The superconducting linac of Chengdu THz Free Electron Laser (CTFEL) facility was used for FLASH-IR, a diamond radiation detector and a CeBr3 scintillation detector were used to monitor the time structure and dose rate of FLASH pulses. BALB/c nude mice received whole abdominal 6 MV X-ray FLASH-IR or CONV-IR, the prescribed dose was 15 Gy or 10 Gy and the delivered absolute dose was monitored with EBT3 films. The mice were either euthanized 24 h post-IR to evaluate acute tissue responses or followed up for 6 weeks to observe late-stage responses and survival probability. Complete blood count, histological analyses, and measurement of cytokine expression and redox status were performed. RESULTS: The mean dose rate of >150 Gy/s and instantaneous dose rate of >5.5 × 105  Gy/s was reached in FLASH-IR at the center of mice body. After 6 weeks' follow-up of mice that received 15 Gy IR, the FLASH group showed faster body weight recovery and higher survival probability than the CONV group. Histological analysis showed that FLASH-IR induced less acute intestinal damage than CONV-IR. Complete blood count and cytokine concentration measurement found that the inflammatory blood cell counts and pro-inflammatory cytokine concentrations were elevated at the acute stage after both FLASH-IR and CONV-IR. However, FLASH irradiated mice had significantly fewer inflammatory blood cells and diminished pro-inflammatory cytokine at the late stage. Moreover, higher reactive oxygen species (ROS) signal intensities but significantly reduced lipid peroxidation were found in the FLASH group than in the CONV group in the acute stage. CONCLUSIONS: The radioprotective effect of 6 MV X-ray FLASH-IR was observed. The differences in inflammatory responses and redox status between the two groups may be the factors responsible for reduced radiotoxicities following FLASH-IR. Further studies are required to thoroughly evaluate the impact of ROS on FLASH effect.

Characterization and Transcriptome Analysis of a Long-Chain n-Alkane-Degrading Strain Acinetobacter pittii SW-1.

Strain sw-1, isolated from 7619-m seawater of the Mariana Trench, was identified as Acinetobacter pittii by 16S rRNA gene and whole-genome sequencing. A. pittii sw-1 was able to efficiently utilize long-chain n-alkanes (C18-C36), but not short- and medium-chain n-alkanes (C8-C16). The degradation rate of C20 was 91.25%, followed by C18, C22, C24, C32, and C36 with the degradation rates of 89.30%, 84.03%, 80.29%, 30.29%, and 13.37%, respectively. To investigate the degradation mechanisms of n-alkanes for this strain, the genome and the transcriptome analyses were performed. Four key alkane hydroxylase genes (alkB, almA, ladA1, and ladA2) were identified in the genome. Transcriptomes of strain sw-1 grown in C20 or CH3COONa (NaAc) as the sole carbon source were compared. The transcriptional levels of alkB and almA, respectively, increased 78.28- and 3.51-fold in C20 compared with NaAc, while ladA1 and ladA2 did not show obvious change. The expression levels of other genes involved in the synthesis of unsaturated fatty acids, permeases, membrane proteins, and sulfur metabolism were also upregulated, and they might be involved in n-alkane uptake. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) confirmed that alkB expression was significantly induced by C20, C24, and C32, and almA induction extent by C24 and C32 was higher than that with C20. Furthermore, ladA2 expression was only induced by C32, and ladA1 expression was not induced by any of n-alkanes. In addition, A. pittii sw-1 could grow with 0%-3% NaCl or 8 out of 10 kinds of the tested heavy metals and degrade n-alkanes at 15 °C. Taken together, these results provide comprehensive insights into the degradation of long-chain n-alkanes by Acinetobacter isolated from the deep ocean environment.

Magnetic resonance-based synthetic computed tomography images generated using generative adversarial networks for nasopharyngeal carcinoma radiotherapy treatment planning.

BACKGROUND AND PURPOSE: To investigate the feasibility of synthesizing computed tomography (CT) images from magnetic resonance (MR) images using generative adversarial networks (GANs) for nasopharyngeal carcinoma (NPC) intensity-modulated radiotherapy (IMRT) planning. MATERIALS AND METHODS: Conventional T1-weighted MR images and CT images were acquired from 173 NPC patients. The MR and CT images of 28 patients were randomly chosen as the independent tested set. The remaining images were used to build a conditional GAN (cGAN) and a cycle-consistency GAN (cycleGAN). A U-net was used as the generator in cGAN, whereas a residual-Unet was used as the generator in cycleGAN. The cGAN was trained using the deformable registered MR-CT image pairs, whereas the cycleGAN was trained using the unregistered MR and CT images. The generated synthetic CT (SCT) images from cGAN and cycleGAN were compared with the true CT images with respect to their Hounsfield Unit (HU) discrepancy and dosimetric accuracy for NPC IMRT plans. RESULTS: The mean absolute errors within the body were 69.67 ±â€¯9.27 HU and 100.62 ±â€¯7.39 HU for the cGAN and cycleGAN, respectively. The 2%/2-mm γ passing rates were (98.68 ±â€¯0.94)% and (98.52 ±â€¯1.13)% for the cGAN and cycleGAN, respectively. Meanwhile, the absolute dose discrepancies within the regions of interest were (0.49 ±â€¯0.24)% and (0.62 ±â€¯0.36)%, respectively. CONCLUSION: Both cGAN and cycleGAN could swiftly generate accurate SCT volume images from MR images, with high dosimetric accuracy for NPC IMRT planning. cGAN was preferable if high-quality MR-CT image pairs were available.

Knockdown of cathepsin L sensitizes ovarian cancer cells to chemotherapy.

Ovarian cancer is a leading gynecological malignancy associated with high mortality. The development of acquired drug resistance is the primary cause of chemotherapy failure in the treatment of ovarian cancer. To examine the mechanism underlying paclitaxel resistance in ovarian cancer and attempt to reverse it, the present study induced a TAX-resistant ovarian cancer cell line, SKOV3/TAX. Cathepsin L (CTSL) has been found to be overexpressed in ovarian cancer. The aim of the present study was to investigate the possible involvement of CTSL in the development of TAX resistance in ovarian cancer. CTSL expression was knocked down in SKOV3 ovarian cancer cells and their phenotypic changes were analyzed. The effects of silenced CTSL on the resistant cell line were investigated by proliferation and apoptosis analysis compared with control SKOV3 cells. CTSL was more highly expressed in SKOV3/TAX cells compared with SKOV3 cells. Paclitaxel treatment downregulated the expression of CTSL in SKOV-3 but not in the paclitaxel-resistant SKOV3/TAX cells. CTSL small hairpin RNA (shRNA) knockdown significantly potentiated apoptosis induced by paclitaxel compared with SKOV3/TAX cells transfected with control shRNA, suggesting that CTSL contributes to paclitaxel resistance in ovarian cancer cells and that CTSL silencing can enhance paclitaxel-mediated cell apoptosis. Thus, CTSL should be explored as a candidate of therapeutic target for modulating paclitaxel sensitivity in ovarian cancer.

[Discussion about risk and management of Chinese patent medicine with double identity].

Chinese patent medicine with double identity was a special phenomenon, and many preparations not only were prescription drugs but also over the counter ( OTC) drugs, which brought a lot of trouble. Based on statistics of list of OTC medicines of CFDA, related varieties, route of administration and functions of these drugs were searched. The causes of insufficient were analyzed and the potential risk was investigated. To ensure the safety of drug usage for the patient, risk management system should be set up by improving the technical requirements for registration, improving the drug labels and manuals, playing the role of pharmacists in pharmacy services and raising awareness of doctor and patient for these drugs.

Cathepsin L is involved in proliferation and invasion of ovarian cancer cells.

Cathepsin L (CTSL) is a lysosomal cysteine protease that has been found to be overexpressed in ovarian cancer (OC). The aim of the present study was to investigate the possible involvement of CTSL in the development of OC. In this study, RNA interference with a CTSL small hairpin RNA (CTSL-shRNA), and a plasmid carrying CTSL were used to identify the effects of this enzyme on the regulation of the malignant behavior of OC cells. OV-90 and SKOV3 human ovarian cancer cell lines were selected as cell models in vitro and in vivo. The results showed that downregulation of CTSL significantly inhibits the proliferative and invasive capability of SKOV3 cells, and that upregulation of CTSL in OV-90 cells leads to opposite effects. Compared with parental OC cells, cells in which CTSL was silenced exhibited a reduced capacity to develop into tumors in nude mice, while the growth of tumor xenografts derived from these cells was markedly constrained. In conclusion, the results suggested that CTSL contributes to the proliferation and metastasis of OC, and that CTSL may be a novel molecular target for OC treatment.

[Construction of a melon genetic map with fruit and seed QTLs].

A genetic map of melon was constructed using 143 F2 population developed from a cross between two distant lines Ano2 of Japan and Hami melon K413. The map contains 12 linkage groups and 142 markers, including 121 AFLPs, 16 SSRs, 3 STSs, 2 trait markers and covers 1 014.2 cM. Composite interval mapping (CIM) method was used to detect QTLs involved in melon fruit and seed traits: fruit length (FL), fruit width (FW), fruit shape (length/width, FS), centre sugar (CS), edge sugar (ES), flesh texture (FT), seed length (SL), seed width (SW), seed shape (SS), and seed weight (SW). The result showed that Flesh was located between AFLP markers NDAA and NCFA on C9. A total of 25 QTLs were detected for other traits and some QTLs were co-located with each other. The QTLs Sl5.1, Sw5.1, and Swt5.1 located on linkage C5 between NCA and N73C explained a significant portion of associated phenotypic variation (R2=17%, 19%, 23%). The allele from Ano2 obviously suppressed the length, width, and weight of melon seed; the QTLs between N73A and NFDA on C8 were involved in seed width, shape, and weight; the QTL Fs8.1 on C8 was detected using both F2 and F3 fruit data and explained a significant portion of phenotypic variation 25% and 19%. Fs8.1 showed partly dominant, and the allele from Ano2 sup-pressed elongation of fruit to form round melon. The QTLs related to centre sugar, edge sugar, and fruit texture were also detected in this research.

[Evaluation of jaws-only intensity-modulated radiation therapy for nasopharyngeal carcinoma].

OBJECTIVE: To investigate the feasibility and efficiency of jaws-only intensity-modulated radiation therapy (JO-IMRT) in treatment of nasopharyngeal carcinoma (NPC) using direct aperture optimization (DAO) technique and the independent jaws of linear accelerator. METHODS: Both JO-IMRT and MLC-IMRT were planed in 10 NPC cases. The differences in the target coverage and dose uniformity, as well as the total monitor units and delivery times of the two IMRT plans were compared. RESULTS: All the tested plans met the clinical requirement of the designed simplified IMRT (sIMRT). The conformal index (CI) of JO-IMRT and MLC-IMRT were 0.941±0.015 and 0.981±0.013, respectively (P<0.001), showing a minor superiority of MLC-IMRT. While controlling the total segment numbers to approach the limitation of sIMRT, the two therapies showed a total MU of 474.3 and 419.6 (P<0.05) with delivery times of 8.0 and 7.5 min (P<0.01), respectively. The efficiency of JO-IMRT was slightly lower than that of MLC-IMRT. CONCLUSION: JO-IMRT can meet the sIMRT requirement in NPC treatment, and is feasible as an alternative treatment modality for the centers not equipped with MLC in their accelerators.

[Inhibitory effects of recombinant adenovirus carrying human endostatin gene on the growth of human pancreatic carcinoma xenograft in nude mice].

OBJECTIVE: To evaluate the inhibitory effect of recombinant adenovirus carrying human endostatin gene (Ad-endo) on the growth of human pancreatic carcinoma xenograft in nude mice. METHODS: The expression of endostatin in human pancreatic carcinoma Capan-2 cells was examined by RT-PCR after infection with Ad-endo. The supernatants of Capan-2 cells were collected after 48 h of infection with Ad-endo as the conditioned medium for human umbilical vein endothelial cells (HUVECs), whose proliferation in vitro was assayed. Capan-2 cell xenografts were established to determine the antitumoral effects of Ad-endo in vivo. The intratumoral microvessel density (MVD) was evaluated using CD31 staining. RESULTS: The expression of endostatin gene was detected by PT-PCR in infected Capan-2 cells. The conditioned medium from Ad-endo-infected cells significantly inhibited HUVEC proliferation (P<0.05). Ad-endo significantly suppressed the growth of Capan-2 tumor xenografts in nude mice (P<0.05), and the MVD decreased significantly in the treated tumor (P<0.05) as compared with that in the control group. CONCLUSION: Adenovirus carrying human endostatin gene produces inhibitory effects on the growth of human pancreatic carcinoma tumors in nude mice.

[Measurements and comparisons for data of small beams of linear accelerators].

BACKGROUND AND OBJECTIVE: Accurate data acquisition is very important to establish a reliable dose calculation model of the treatment planning system for small radiation fields in intensity modulated radiation therapy (IMRT) and stereotactic radiotherapy (SRT). This study was to analyze and compare small-field measurements using different methods and ionization chambers. METHODS: Three types of farmer chambers were used, with active volumes of 0.65 cc, and 0.13 cc, 0.01 cc, respectively. The beam data, including the total scatter factor (Scp), collimator scatter factor (Sc), tissue-maximum ratio (TMR), were acquired in a 30 cm x 30 cm x 30 cm3 water phantom under two linear accelerators. Measurements were performed at accelerating potentials of 4, 6, and 8 MV with the beam size ranging from 1 cm x 1 cm to 10 cm x 10 cm. The measurements were analyzed and compared. RESULTS: For the beam size of >or=3 cm x 3 cm, the differences in Scp and Sc measurements of the 0.65 cc, 0.13 cc and 0.01 cc ion chambers were within 0.8%, while the differences were much greater for the beam size of less than 3 cm x 3 cm (the maximum difference reached 64%). Using 4, 6 and 8 MV X-rays, Sc measured by the 0.13 cc chamber with an elongated source-to-surface distance (SSD) (>150 cm) were 25.4%, 6.9%, 24.6%, and 1.4%, 1.4%, 2.2% greater than those measured by a standard SSD (100 cm) for 1 cm x 1 cm and 2 cm x 2 cm beams respectively; although there was no significant difference in Sc measurements for the beams of >or=2 cm x 2 cm using the elongated SSD of the 0.13 cc and the 0.01 cc ion chambers, Sc measured by the 0.13 cc ion chamber were 0.2%, 8.5%, 3.4% less than those measured by the 0.01 cc ion chamber for the 1 cm x 1 cm beam. For the 1 cm x 1 cm beam, the TMR of the depth deeper than 15 cm measured with the 0.01 cc ion chamber was about 4% different compared with that measured with the 0.13 cc ion chamber; for radiation fields of >or=2 cm x 2 cm, the differences of TMR between the 0.01 cc and 0.13 cc chambers were within 1%. For the radiation fields of >or=3 cm x 3 cm, the measured TMR values had a good consistency with the calculated values obtained from the percentage depth doses (PDDs) at the depth of 0 to 15 cm; but the two values were obviously different at the depths of deeper than 15 cm (>2%). CONCLUSIONS: For the measurement of small fields, the choice of a suitable detector is important due to the lack of lateral electron equilibrium. Misuse of the detector may affect the accuracy of the measurements for small radiation fields. When the lateral electron equilibrium is not established, the size of the detector used to measure the absorbed dose on the central axis should be considerably smaller than the field size.