Objective We developed a method to expand margin of beam aperture for VMAT treatment planning of breast cancer and evaluated its effectiveness in clinic. Methods An expanded VMAT (E-VMAT) plan for breast cancer using Pinnacle39. 10 planning system was made. A small tissue-equivalent bolus was added at the middle of the breast surface as part of the target and the VMAT plan was generated with beam aperture automatically expanded. Then the tissue-equivalent bolus was removed and the final dose distribution was calculated. Ten patients with breast cancer undergoing breast conserving surgery were tested. The dosimetrical metrics and delivery efficiency were compared between the E-VMAT plans and the routine VMAT plans. Results On the BEV view, it was observed that in E-VMAT plans the collimator and MLC leaf positions was extended outside the skin along the anterior-posterior direction of the thorax. There were no significant differences in conformity index and homogeneity index of target volume between the two types of plans and the planned delivery efficiency was consistent (P>0. 05). Conclusions The method established in this study can automatically generate expansion of VMAT beam apertures and prevent missing of target volume due to respiratory motion and/ or setup error of the patient. The method does not require programming skill and available for different treatment planning systems.

Microorganisms are the dominant players driving the degradation and transformation of chloramphenicol (CAP) in the environment. However, little bacterial strains are able to efficiently degrade and mineralize CAP, and the CAP degrading pathways mediated by oxidative reactions remain unclear. In this study, a highly efficient CAP-degrading microbial consortium, which mainly consists of Rhodococcus (relative abundance >70%), was obtained through an enrichment process using CAP-contaminated activated sludge as the inoculum. A bacterial strain CAP-2 capable of efficiently degrading CAP was isolated from the consortium and identified as Rhodococcus sp. by 16S rRNA gene analysis. Strain CAP-2 can efficiently degrade CAP under different nutrient conditions. Based on the biotransformation characteristics of the detected metabolite p-nitrobenzoic acid and the reported metabolites p-nitrobenzaldehyde and protocatechuate by strain CAP-2, a new oxidative pathway for the degradation of CAP was proposed. The side chain of CAP was oxidized and broken to generate p-nitrobenzaldehyde, which was further oxidized to p-nitrobenzoic acid. Strain CAP-2 can be used to further study the molecular mechanism of CAP catabolism, and has the potential to be used in in situ bioremediation of CAP-contaminated environment.
Biodegradation, Environmental ; Chloramphenicol ; RNA, Ribosomal, 16S/genetics* ; Rhodococcus/genetics* ; Sewage

Objective: To investigate the difference of prognostic factors and recurrence rates between papillary thyroid microcarcinoma (PTMC) and lager papillary thyroid carcinoma (PTC) and analyze the clinical pathological characteristics of PTMC suitable for surgery. Methods: A retrospective analysis on the clinicopathological features, expression level of of v-raf murine sarcoma viral oncogene homolog B1 (BRAF) V600E gene mutation and pigment epithelium-derived factor (PEDF), and postoperative follow-up results of the 251 PTC patients who underwent surgical treatment from October 2011 to October 2013, including 169 cases with PTMC and 82 with lager PTC (Tumor diameter>1 cm). Results: The BRAF V600E mutation rates of PTMC and lager PTC patients are 65.1%(110/169)and 78.0% (64/82) respectively, and the difference is statistically significant (P<0.05). The prevalence of extrathyroidal invasion (7.1%) and lymph nodes metastasis (27.2%) of the patients with PTMC were significantly lower than those of the patients with larger PTC (15.9% and 46.3%, respectively)(P<0.01). The follow-up durations for PTMC and lager PTC were (45.6±3.6) months and (45.0±3.4) months, respectively (P>0.05). There was no statistic significance for the difference in age, gender, coexistent hashimoto′s thyroiditis, PEDF expression, and recurrence rate between the patients with PTMC and with larger PTC (P>0.05). The recurrence rate of the patients who have the high risk factors of PTMC was 1.6%(2/122)and that of larger PTC was 4.9% (4/82). Conclusions Extrathyroid invasion, lymph node metastases and BRAF V600E gene mutation are the high risk factors of recurrent PTMC. The same treatment strategy should be considered for PTMC with coexistent high risk factors as that for larger PTC. For PTMC with BRAF V600E gene mutation, earlier surgical treatment is suggested. PTMC patients with BRAF V600E gene mutation and high cell subtype are suggested to undergo total thyroidectomy for the first operation in order to reduce the potential risk of recurrence.