Biocontrol and Growth Promotion Potential of Bacillus subtilis CTXW 7-6-2 against Rhizoctonia solani that Causes Tobacco Target Spot Disease.

Fungal diseases form perforated disease spots in tobacco plants, resulting in a decline in tobacco yield and quality. The present study investigated the antagonistic effect of Bacillus subtilis CTXW 7-6-2 against Rhizoctonia solani, its ability to promote the growth of tobacco seedlings, and the expression of disease resistance-related genes for efficient and eco-friendly plant disease control. Our results showed that CTXW 7-6-2 had the most vigorous growth after being cultured for 96 h, and its rate of inhibition of R. solani growth in vitro was 94.02%. The volatile compounds produced by CTXW 7-6-2 inhibited the growth of R. solani significantly (by 96.62%). The fungal growthinhibition rate of the B. subtilis CTXW 7-6-2 broth obtained after high-temperature and no-high-temperature sterile fermentation was low, at 50.88% and 54.63%, respectively. The lipopeptides extracted from the B. subtilis CTXW 7-6-2 fermentation broth showed a 74.88% fungal growth inhibition rate at a concentration of 100 mg/l. Scanning and transmission electron microscopy showed some organelle structural abnormalities, collapse, shrinkage, blurring, and dissolution in the R. solani mycelia. In addition, CTXW 7-6-2 increased tobacco seedling growth and improved leaf and root weight compared to the control. After CTXW 7-6-2 inoculation, tobacco leaves showed the upregulation of the PDF1.2, PPO, and PAL genes, which are closely related to target spot disease resistance. In conclusion, B. subtilis CTXW 7-6-2 may be an efficient biological control agent in tobacco agriculture and enhance plant growth potential.

[Diagnostic value of dual-head 18F-FDG imaging in metastatic lesion with unknown primary tumour].

OBJECTIVE: To investigate the diagnostic value of dual-head (18)F-fluorodeoxyglucose ((18)F-FDG) imaging in metastatic lesion with unknown primary tumour (UPT). METHODS: Seventy patients with UPT underwent dual-head (18)F-FDG imaging after iv (18)F-FDG 1.85 MBq/kg. The primary tumour was diagnosed according to the FDG uptake and T/N value. RESULTS: Of the 70 patients, the primary tumour was identified by positive FDG imaging and finally confirmed pathologically in 58 patients (82.9%), and 12 patients had a negative FDG imaging (17.1%). Forty-two of the 58 positive patients were found to have lung cancer (72.4%). Among the 12 negative patients, their primary tumour was then identified by other diagnostic procedures in 5 patients (41.7%), in 1 patient, the primary site was detected during follow-up, however, the primary tumour was never detected in the rest 6 patients. CONCLUSION: Dual-probe (18)F-FDG imaging is a simple, quick, non-invasive and sensitive technique with an accuracy over 80% in the diagnosis of unknown primary tumour. The lung is found to be the most frequent primary site. Dual-probe (18)F-FDG imaging can be recommended as the first diagnostic choice for UPT.

[A new applicator with regulatable air bag designed for intracavitary brachytherapy of nasopharyngeal carcinoma].

BACKGROUND & OBJECTIVE: Nasopharynx applicator used in intracavitary brachytherapy plays an important role in the radiotherapy of nasopharyngeal carcinoma (NPC), its quality affects the efficiency of treatment. This study was to design a new applicator for clinical use. METHODS: An inexpensive, reusable, and flexible latex nasopharynx applicator was designed. An air bag was placed at 15 mm from the foreside of the applicator, clung to the tube. The edge of air bag is tangent to the axis of tube. When the bag was full of air, the tube would hunch reversely,close to nasopharyngeal vault. After introduced into nasopharynx through middle nasal meatus, the applicator could be fixed in suitable position by its rotation, and air bag regulation, and confirmed its position by simulation. RESULTS: A total of 221 patients with NPC were treated with external beam radiation therapy in our hospital, and boosted HDR brachytherapy using this new applicator. The response rate was 92.6% in the primary tumor group (200/216), and 100% in the recurrent tumor group (5/5). Mucosal necrosis in the posterior or anterior wall of nasopharynx occurred in 5 patients, 8 patients experienced nasal congestion and nasal synechia. CONCLUSIONS: This new nasopharynx applicator is easy to operate, painless, and well dosage-distributed. Mucosal necrosis is likely due to higher fractional dose.