Gas-phase synthesis of [OU-X]+ (X = Cl, Br and I) from a UO22+ precursor using ion-molecule reactions and an [OUCH]+ intermediate.

Difficulty in the preparation of gas-phase ions that include U in middle oxidation states(III,IV) have hampered efforts to investigate intrinsic structure, bonding and reactivity of model species. Our group has used preparative tandem mass spectrometry (PTMS) to synthesize a gas-phase U-methylidyne species, [OUCH]+, by elimination of CO from [UO2(CCH)]+ [M. J. van Stipdonk, I. J. Tatosian, A. C. Iacovino, A. R. Bubas, L. Metzler, M. C. Sherman and A. Somogyi, J. Am. Soc. Mass Spectrom., 2019, 30, 796-805], which has been used as an intermediate to create products such as [OUN]+ and [OUS]+ by ion-molecule reactions. Here, we investigated the reactions of [OUCH]+ with a range of alkyl halides to determine whether the methylidyne is a also a useful intermediate for production and study of the oxy-halide ions [OUX]+, where X = Cl, Br and I, formally U(IV) species for which intrinsic reactivity data is relatively scarce. Our experiments demonstrate that [OUX]+ is the dominant product ion generated by reaction [OUCH]+ with neutral regents such as CH3Cl, CH3CH2Br and CH2CHCH2I.

Intrinsic reactivity of [OUCH]+ : Apparent synthesis of [OUS]+ by reaction with CS2.

RATIONALE: Building on our report that collision-induced dissociation (CID) can be used to create the highly reactive U-alkylidyne species [O=U≡CH]+ , our goal was to determine whether the species could be as an intermediate for synthesis of [OUS]+ by reaction with carbon disulfide (CS2 ). METHODS: Cationic uranyl-propiolate precursor ions were generated by electrospray ionization, and multiple-stage CID in a linear trap instrument was used to prepare [O=U≡CH]+ . Neutral CS2 was admitted into the trap through a modified He inlet and precision leak valves. RESULTS: The [O=U≡CH]+ ion reacts with CS2 to generate [OUS]+ . CID of [OUS]+ causes elimination of the axial sulfide ligand to generate [OU]+ . Using isotopically labeled reagent, we found that [OUS]+ reacts with O2 to create [UO2 ]+ . CONCLUSIONS: [O=U≡CH]+ proves to be a useful reagent ion for synthesis of [OUS]+ , a species that to date has only been created by gas-phase reactions of U+ and U2+ . Dissociation of [OUS]+ to create [OU]+ , but not [US]+ , and the efficient conversion of the species into [UO2 ]+ , is consistent with the relative differences in U-O and U-S bond energies.

Nasopharyngeal granulomatous mass after radiotherapy for nasopharyngeal carcinoma.

OBJECTIVE: To evaluate the diagnosis, management and nasal endoscopic surgical outcome of nasopharyngeal granulomatous mass in post-radiation nasopharyngeal carcinoma (NPC) patients. MATERIALS AND METHODS: A total of 23 cases of granulomatous mass after radiotherapy for NPC from 2008 to 2013 treated with nasal endoscopic surgery were retrospectively reviewed. RESULTS: Radiotherapy dose (p=0.036) and chemotherapy (p<0.001) correlated with the latency period after the treatment against NPC. The symptoms of the 23 patients before the treatment were nonspecific including nasal obstruction, purulent discharge, headache, epistaxis, foreign body sensation and/or hearing impairment. 12 patients (52.2%) were misdiagnosed to be recurrence of NPC by imaging examination (CT/MRI). After the endoscopic surgery treatment, 18 patients were disease free while the other 5 patients had developed a recurrence. Four of those five recurrent patients were cured with the repeated treatment. Histologic findings of granulation tissue with fibrin and inflammatory cells were found in all of the patients. CONCLUSIONS: In situ granulomatous masses in post-radiation NPC patients are very prone to be misdiagnosed as recurrence of nasopharyngeal carcinoma. Chemotherapy is a significant independent factor affecting latency period (p=0.029). The nasal endoscopic surgery is an effective therapy for post-radiation nasopharyngeal granuloma; surgery can not only alleviate symptoms, what is more important, but it also helps to confirm the diagnosis.

Impact of different surgical and postoperative adjuvant treatment modalities on survival of sinonasal malignant melanoma.

BACKGROUND: The role of postoperative adjuvant treatment for sinonasal malignant melanoma remains unclear. This study evaluates the impact of three different surgical and postoperative adjuvant treatment modalities: surgery alone(open and endoscopic approaches), surgery plus radiotherapy and surgery, radiotherapy plus chemotherapy on survival of patients with primary sinonasal malignant melanoma (SMM). METHODS: The data of 69 patients who underwent primary surgical treatments at Eye & ENT hospital of Fudan University between January 1st, 2000 and December 31st, 2010 were retrospectively reviewed. Survival comparison of different surgical and postoperative adjuvant treatment modalities (surgery alone, surgery plus radiotherapy and surgery, radiotherapy plus chemotherapy), as well as survival comparison between open and endoscopic surgical approaches were performed. Curves depicting survival were performed using Kaplan-Meier method. Statistical analysis was performed using log-rank test software SPSS19 and p < .05 is considered as statistically significant. RESULTS: The median overall survival time was found to be 18 months for surgery alone (27 cases), 32 months for surgery plus radiotherapy (24 cases), 42 months for surgery, radiotherapy plus chemotherapy (18 cases). The 3 and 5 year survival rates for groups mentioned above were 14.8% and 5.6%, 45.1% and 31.6%, 55% and 32.1%, respectively. Statistical significances were found not only between surgery alone and surgery plus radiotherapy treatment group (P = 0.012), but also surgery alone and surgery, radiotherapy plus chemotherapy group (P = 0.002). There was no statistically significant survival difference found between the two different surgical approaches (41 cases for open approach and 28 cases for endoscopic approach). CONCLUSIONS: Sinonasal malignant melanoma is a disease with a poor prognosis. Patients who underwent surgery plus radiotherapy or surgery, radiotherapy plus chemotherapy had better survival outcomes than those underwent surgery alone. Endoscopic approach provided similar survival outcome as an open approach.