Engineered platelet cell motors for boosted cancer radiosensitization.

Design of engineered cells to target and deliver nanodrugs to the hard-to-reach regions has become an exciting research area. However, the limited penetration and retention of cell-based carriers in tumor tissue restricted their therapeutic efficiency. Inspired by the enhanced delivery behavior of mobile micro/nanomotors, herein, urease-powered platelet cell motors (PLT@Au@Urease) capable of active locomotion, tumor targeting, and radiosensitizers delivery were designed for boosting radiosensitization. The engineered platelet cell motors were constructed by in situ synthesis and loading of radiosensitizers gold nanoparticles in platelets, and then conjugation with urease as the engine. Under physiological concentration of urea, thrust around PLT@Au@Urease motors can be generated via the biocatalytic reactions of urease, leading to rapid tumor cell targeting and enhanced cellular uptake of radiosensitizers. Encouragingly, in comparison with engineered PLT without propulsion capability (PLT@Au), the self-propelled PLT@Au@Urease motors could significantly increase intracellular ROS level and exacerbate nuclear DNA damage induced by γ-radiation, resulting in a remarkably high sensitization enhancement rate (1.89) than that of PLT@Au (1.08). In vivo experiments with 4 T1-bearing mice demonstrated that PLT@Au@Urease in combination with radiation therapy possessed good antitumor performance. Such an intelligent cell motor would provide a promising approach to enhance radiosensitization and broaden the applications of cell motor-based delivery systems.

LUMO-Mediated Se and HOMO-Mediated Te Nanozymes for Selective Redox Biocatalysis.

Selenium (Se) and tellurium (Te) nanomaterials with novel chain-like structures have attracted widespread interest owing to their intriguing properties. Unfortunately, the still-unclear catalytic mechanisms have severely limited the development of biocatalytic performance. In this work, we developed chitosan-coated Se nanozymes with a 23-fold higher antioxidative activity than Trolox and bovine serum albumin coated Te nanozymes with stronger prooxidative biocatalytic effects. Based on density functional theory calculations, we first propose that the Se nanozyme with Se/Se2- active centers favored reactive oxygen species (ROS) clearance via a LUMO-mediated mechanism, while the Te nanozyme with Te/Te4+ active centers promoted ROS production through a HOMO-mediated mechanism. Furthermore, biological experiments confirmed that the survival rate of γ-irritated mice treated with the Se nanozyme was maintained at 100% for 30 days by inhibiting oxidation. However, the Te nanozyme had the opposite biological effect via promoting radiation oxidation. The present work provides a new strategy for improving the catalytic activities of Se and Te nanozymes.

Design of Monovalent Cerium-Based Metal Organic Frameworks as Bioinspired Superoxide Dismutase Mimics for Ionizing Radiation Protection.

Superoxide dismutase (SOD) is one of the major antioxidants in vivo and is expected to play critical roles on the defense against reactive oxygen species (ROS)-mediated damages, such as ionizing radiation damages. Herein, inspired by the function and structure of natural SODs and cerium oxide nanozymes, two monovalent cerium-based metal organic frameworks (Ce-MOFs), CeIIIBTC and CeIVBTC, were designed for superoxide radical (O2•-) elimination and ionizing radiation protection. These two Ce-MOFs selectively scavenge O2•- and are excellent SOD mimics. Like natural SODs and cerium oxide nanozymes, the SOD-like catalytic mechanism of Ce-MOFs involves a cycle between Ce(IV) and Ce(III). Furthermore, by constructing monovalent Ce-MOFs, we found that high-valent CeIVBTC are more effective SOD-like nanozymes compared to CeIIIBTC. With smaller size, better monodispersity, and more effective SOD-like activity, CeIVBTC nanozymes were further applied for ionizing radiation protection. Both in vitro and in vivo results demonstrated that CeIVBTC nanozymes could efficiently scavenge ROS, prevent cells from γ-ray radiation-induced cell viability decrease and DNA damages, and improve the survival rate of irradiated mice by recovering the bone marrow DNA damage and alleviating oxidative stress of tissues. The protective effect and good biocompatibility of CeIVBTC nanozymes will enable the development of Ce-MOFs-based radioprotectants and facilitate treatment of other ROS-related diseases.

CRISRP/Cas9-Mediated Targeted Mutagenesis of Tomato Polygalacturonase Gene (SlPG) Delays Fruit Softening.

Polygalacturonase (PG) gene has been documented as a key candidate for the improvement of fruit firmness, which is a target trait for tomato production because it facilitates transportation and storage. To reduce the expression of the PG gene, most of the elite commercial tomato varieties were obtained by RNA interference technology. However, this approach of producing commercialized tomatoes by integration of the exogenous gene is controversial. In this work, CRISPR/Cas9 technology was used to induce the targeted mutagenesis of the SlPG gene to delay the softening of tomato fruit. Results showed that the SlPG gene was frameshift mutated by 4 bp deletion, 10 bp deletion, and 1 bp insertion, which generated premature translation termination codons. Compared with wild-type (WT), homozygous T1-generation tomato plants exhibited late fruit softening under natural conditions. Consistent with this phenomenon, the firmness value of WT fruit was lower in slpg mutant fruit, and the physiological loss of water was higher. Collectively, these data demonstrate that the mutation of the SlPG gene delays tomato fruit softening. More importantly, 8 out of 20 transgene-free tomato plants, which were homozygous for null alleles of SlPG, were separated in the T3-generation of line slpgT2-#2. This transgene-free slpg may provide materials for more in-depth research of SlPG functions and the molecular mechanism of fruit softening in tomatoes.

Introduction of Exogenous Glycolate Catabolic Pathway Can Strongly Enhances Photosynthesis and Biomass Yield of Cucumber Grown in a Low-CO2 Environment.

Carbon dioxide (CO2) is very important for photosynthesis of green plants. CO2 concentration in the atmosphere is relatively stable, but it drops sharply after sunrise due to the tightness of the greenhouse and the absorption of CO2 by vegetable crops. Vegetables in greenhouses are chronically CO2 starved. To investigate the feasibility of using genetic engineering to improve the photosynthesis and yield of greenhouse cucumber in a low CO2 environment, five genes encoding glyoxylate carboligase (GCL), tartronic semialdehyde reductase (TSR), and glycolate dehydrogenase (GlcDH) in the glycolate catabolic pathway of Escherichia coli were partially or completely introduced into cucumber chloroplast. Both partial pathway by introducing GlcDH and full pathway expressing lines exhibited higher photosynthetic efficiency and biomass yield than wild-type (WT) controls in low CO2 environments. Expression of partial pathway by introducing GlcDH increased net photosynthesis by 14.9% and biomass yield by 44.9%, whereas the expression of the full pathway increased seed yield by 33.4% and biomass yield by 59.0%. Photosynthesis, fluorescence parameters, and enzymatic measurements confirmed that the introduction of glycolate catabolic pathway increased the activity of photosynthetic carbon assimilation-related enzymes and reduced the activity of photorespiration-related enzymes in cucumber, thereby promoting the operation of Calvin cycle and resulting in higher net photosynthetic rate even in low CO2 environments. This increase shows an improvement in the efficiency of the operation of the photosynthetic loop. However, the utilization of cucumber of low concentration CO2 was not alleviated. This study demonstrated the feasibility of introducing the pathway of exogenous glycolate catabolic pathway to improve the photosynthetic and bio-yield of cucumber in a low CO2 environment. These findings are of great significance for high photosynthetic efficiency breeding of greenhouse cucumber.

[Clinical value of pleural biopsy in the etiological diagnosis of children with pleurisy].

OBJECTIVE: To investigate the clinical value of pleural biopsy in the etiological diagnosis of pleurisy in children. METHOD: Totally 213 cases with pleurisy, who underwent pleural biopsy and hospitalized in Children's Hospital of Chongqing Medical University from January 2007 to April 2014 were enrolled into this study. Clinical symptoms, imaging manifestations, pleural fluid characteristics, the results of pleural biopsy and postoperative complications were retrospectively analyzed to evaluate the clinical value and security of pleural biopsy in making the etiological diagnosis of pleurisy. RESULT: (1) Of the 213 cases, 144 were boys and 69 were girls, their mean age was (6. 5 ± 4. 1) years. (2) Two hundred and thirteen patients had a surgical pleural biopsy under general anesthesia, the cause of 97 cases (45. 5%) were made clear by histopathological examination, including 35 purulent pleurisy, 55 tuberculous pleurisy and 7 paragonimus infection. For the remaining 83 (41. 3%) cases a final diagnosis was made based on the full analysis of clinical data, including 63 cases of purulent pleurisy, 3 cases of tuberculous pleurisy and 17 cases of paragonimiasis pleurisy but for 33 patients no exact cause was found at the end. (3) The mean operating time of the biopsy was (1. 4 ± 0. 6) hours. Seventy one (33. 3%) patients required blood transfusion during or after the operation. Thirty one (14. 6%) cases used the ventilator after surgery, and the ventilator supporting time was (6. 6 ± 5. 8) hours on average. The wound healing reached grade A in 200 cases (93. 9%), grade B in 13 cases (14. 6%). Postoperative complications included pneumothorax in 92 cases (43. 2%), subcutaneous emphysema in 18 cases (8. 5%), bronchopleural fistula in 3 cases(1. 4%). The average days of hospitalization was (17. 7 ± 7. 1) d. CONCLUSION: Pleural biopsy is of great diagnostic value in the etiological diagnosis and differential diagnosis of pleurisy in children, and it is considered reasonable to be used in the clinical practice when appropriate.

[Clinical value of pleural biopsy in the diagnosis of children with tuberculous pleurisy].

OBJECTIVE: To explore the value of pleural biopsy in the diagnosis of tuberculous pleurisy in children. METHOD: Fifty-one cases with tuberculous pleurisy, whose diagnosis was established according to the clinical diagnostic criteria of the child pulmonary tuberculosis formulated by the Chinese Medical Association (CMA) in 2006, after pleural biopsy hospitalized in Children's Hospital of Chongqing Medical University from Jan. 1, 2007 to Jan. 1, 2013 were enrolled into this study. Clinical symptoms, history traits, laboratory examination, imaging tests, pleural fluid characteristics and the results of pleural biopsy were retrospectively analyzed. Medical records of the cases who were diagnosed with tuberculous pleurisy by histological examination were reviewed to assess tuberculosis detection rate of pleural biopsy and to get the percentage of cases with a preoperative diagnosis inconsistent with the final diagnosis. RESULT: There were 35 boys and 16 girls, and the mean age was (9.7 ± 3.5) years. The common symptoms included fever (82%), cough (71%) , chest pain (23%), weakness (10%) and shortness of breath (10%); 27% (14/51) children had shown tuberculosis toxic symptoms; 76% (39/51) patients had BCG vaccination history; 12% (6/51) cases had a history of contact with tuberculosis patients. The positive rates of the tuberculin skin test, serum tuberculosis antibody detection, detection of Mycobacterium tuberculosis DNA by polymerase chain reaction, acid-fast bacillus test of sputum (or gastric juice) smear, acid-fast bacilli (AFB) smear and culture of pleural effusion were respectively 61% (20/33), 6% (3/46), 0 (0/12), 4% (1/27), 22% (7/32). Pleural effusion was found by using imaging tests in 50 cases, among whom 28 cases (55%) with encapsulated effusion, and the multilocular cysts separated by fibrous tissue in 12 patients (23%) . Other features included pleural thickening (53%) , hilar and mediastinal lymph-nodes enlargement (14%) and white nodules of calcification (10%) . Thoracocentesis was performed in 31 cases, and pleural effusion obtained from which were exudative. The cell count, mainly mononuclear cells, increased in 28 patients (90%) . Among the 51 children investigated, 47 (92%) were histologically diagnosed to be tuberculous pleurisy. The typical pathologic changes of tuberculosis (caseous necrosis, granulomas, Langhans' giant cells and inflammatory cell infiltration) were observed in 40 cases, granulomatous inflammation without caseous necrosis were the main manifestations in 7 other patients. The pathological changes of the remaining 4 cases were not consistent with the pathological characteristics of tuberculosis. All 47 cases were given a preoperative diagnosis of tuberculous pleurisy (32%), purulent pleurisy (51%) and pleural effusion of unknown origin (17%) respectively before pleural biopsy. Therefore, the tuberculosis detection rate of pleural biopsy was 92%, and the preoperative misdiagnosis rate was 68%. CONCLUSION: Pleural biopsy was of great diagnostic value for children with tuberculous pleurisy.