Performance of a photoelectron momentum microscope in direct- and momentum-space imaging with ultraviolet photon sources.

The Photoelectron-Related Image and Nano-Spectroscopy (PRINS) endstation located at the Taiwan Photon Source beamline 27A2 houses a photoelectron momentum microscope capable of performing direct-space imaging, momentum-space imaging and photoemission spectroscopy with position sensitivity. Here, the performance of this microscope is demonstrated using two in-house photon sources - an Hg lamp and He(I) radiation - on a standard checkerboard-patterned specimen and an Au(111) single crystal, respectively. By analyzing the intensity profile of the edge of the Au patterns, the Rashba-splitting of the Au(111) Shockley surface state at 300 K, and the photoelectron intensity across the Fermi edge at 80 K, the spatial, momentum and energy resolution were estimated to be 50 nm, 0.0172 Å-1 and 26 meV, respectively. Additionally, it is shown that the band structures acquired in either constant energy contour mode or momentum-resolved photoemission spectroscopy mode were in close agreement.

Erratum: Cilostazol eliminates radiation-resistant glioblastoma by re-evoking big conductance calcium-activated potassium channel activity.

[This corrects the article on p. 1148 in vol. 11, PMID: 33948351.].

Cilostazol eliminates radiation-resistant glioblastoma by re-evoking big conductance calcium-activated potassium channel activity.

In spite of radio- and chemotherapy, glioblastoma (GBM) develops therapeutic resistance leading to recurrence and poor prognosis. Therefore, understanding the underlying mechanisms of resistance is important to improve the treatment of GBM. To this end, we developed a radiation-resistant cell model by exposure to consecutive periods of irradiation. Simultaneously, single high-dose irradiation was introduced to determine "when" GBM developed consecutive irradiation-induced resistance (CIIR). We found that CIIR promoted TGF-ß secretion, activated pro-survival Akt, and downregulated p21 in a p53-independent manner. Furthermore, CIIR upregulated multidrug-resistant proteins, resulting in temozolomide resistance. CIIR GBM also enhanced cell mobility and accelerated cell proliferation. The big-conductance calcium-activated potassium channel (BK channel) is highly expressed and activated in GBM. However, CIIR diminishes BK channel activity in an expression-independent manner. Cilostazol is a phosphodiesterase-3 inhibitor for the treatment of intermittent claudication and was able to reverse CIIR-induced BK channel inactivation. Paxilline, a BK channel blocker, promoted cell migration and proliferation in parental GBM cells. In contrast, Cilostazol inhibited CIIR-induced cell motility, proliferation, and the ability to form tumor spheres. Moreover, we established a radiation-resistant GBM in vivo model by intracranially injecting CIIR GBM cells into the brains of NOD/SCID mice. We found that Cilostazol delayed tumor in vivo growth and prolonged survival. As such, inactivation of the BK channel assists GBM in developing radiation resistance. Accordingly, restoring BK channel activity may be an effective strategy to improve therapeutic efficacy, and cilostazol could be repurposed to treat GBM.

Isolated osteoradionecrosis of the dens mimicking metastasis of nasopharyngeal carcinoma after radiotherapy.

Nasopharyngeal carcinoma (NPC) is common in southern China, and radiotherapy remains the mainstay of treatment. A rare late complication of this treatment is the development of osteoradionecrosis (ORN), which seldom involves the cervical spine. We describe a 47-year-old female with undifferentiated carcinoma of the nasopharynx, stage II (T2N0M0), who had undergone radiotherapy 51 months prior, and complained of a twitching headache on neck flexion/extension. Imaging studies, including MRI and 18-fluoro-2-deoxyglucose positron emission tomography scan, suggested the diagnosis of cervical spinal metastasis. However, plasma Epstein-Barr virus DNA was undetectable, favoring absence of tumor recurrence. The patient underwent atlantoaxial sublaminar wiring for an unstable spine and a subsequent transoral biopsy, the histopathologic diagnosis of ORN. The postoperative clinical course was uneventful and follow-up MRI, 2 years later, revealed gradual resolution of the lesion. To our knowledge this is the first report of an isolated ORN lesion of the dens confirmed surgically in a patient with a history of previously treated NPC, a lesion at the cervical spine, and inconclusive imaging and biological marker results. We recommend that ORN be suspected until proven otherwise in a previously irradiated patient.

Outcome of surgical management of persistent or recurrent neck mass in patients with nasopharyngeal carcinoma after radiotherapy.

Nasopharyngeal carcinoma (NPC) patients may have persistent or recurrent neck masses following radiotherapy. The clinicopathological features for these two subgroups are not fully characterized, however. In this study, we reviewed our experiences in patients with neck masses underwent either local excision or neck dissection. Between 1990 and 2004, 37 NPC patients who had persistent (n=18) or recurrent (n=19) neck masses following radiotherapy were enrolled. The clinical and pathological parameters were measured. Squamous cell carcinoma was found in the resected specimens of 72.2% of the patients (13/18) with persistent neck mass and 89.5% of the analogs with the recurrent form (17/19). Extra-nodal tumor extension was noted in 53.8% (7/13) of persistent neck malignancies and 64.7% (11/17) of the recurrent variants. At the time of the neck surgery, individuals with persistent neck malignancies had fewer concomitant distant failures (23.1%, 3/13) as compared to their counterparts with the recurrent form (58.8%, 10/17) (P=0.07). At the end of the follow-up, however, the rates of local and/or distant failures were both high for the persistent (92.3%, 12/13) and recurrent groups (76.5%, 13/17). In conclusion, following radiotherapy for NPC, both persistent and recurrent neck masses were associated with a high rate of squamous cell carcinoma. Although patients with persistent neck malignancies have significantly fewer additional sites of failures at the time of their neck surgeries, they tend to develop local and/or distant recurrences later during follow-up.

Experience in fractionated stereotactic body radiation therapy boost for newly diagnosed nasopharyngeal carcinoma.

PURPOSE: Radiotherapy is the most effective treatment for nasopharyngeal carcinoma (NPC). The aim of this study is to evaluate the efficacy and toxicity of fractionated stereotactic body radiation therapy (SBRT) boost for NPC. METHODS AND MATERIALS: Sixty-four patients with newly diagnosed, nonmetastatic NPC were treated with conventional radiotherapy 64.8-68.4 Gy followed by fractionated SBRT boost 12-15 Gy between January 2002 and July 2004. Most patients (72%) presented with Stage III-IV disease. Fifty-two patients also received cisplatin-based concurrent (38) or neoadjuvant (14) chemotherapy. The major endpoints were local control, overall survival, and complications. RESULTS: All patients finished the planned dose of radiotherapy. After a median follow-up of 31 months (range, 22-54), 15 patients developed tumor recurrences--3 in the nasopharynx, 4 in the neck, 5 in distant sites, 1 in both nasopharynx and neck, 2 in the neck and a distant site. The 3-year actuarial rate of local control was 93.1%, regional control 91.4%, freedom from distant metastasis 90.3%, and overall survival 84.9%, respectively. There were no Grade 4 acute or chronic radiation-related complications. CONCLUSIONS: Fractionated SBRT boost for NPC is technically feasible and provides good local control without any severe complications.