Flexible Phenanthracene Nanotubes for Explosive Detection.

Phenanthracene nanotubes with arylene-ethynylene-butadiynylene rims and phenanthracene walls are synthesized in a modular bottom-up approach. One of the rims carries hexadecyloxy side chains, mediating the affinity to highly oriented pyrolytic graphite. Molecular dynamics simulations show that the nanotubes are much more flexible than their structural formulas suggest: In 12, the phenanthracene units act as hinges that flip the two macrocycles relative to each other to one of two possible sites, as quantum mechanical models suggest and scanning tunneling microscopy investigations prove. Unexpectedly, both theory and experiment show for 13 that the three phenanthracene hinges are deflected from the upright position, accompanied by a deformation of both macrocycles from their idealized sturdy macroporous geometry. This flexibility together with their affinity to carbon-rich substrates allows for an efficient host-guest chemistry at the solid/gas interface opening the potential for applications in single-walled carbon nanotube-based sensing, and the applicability to build new sensors for the detection of 2,4,6-trinitrotoluene via nitroaromatic markers is shown.

Conditional Overall Survival After Diagnosis of Non-Metastatic Colon Cancer: Impact of Laterality, MSI, and KRAS Status.

BACKGROUND: The prognostic relevance of laterality, microsatellite instability (MSI), and KRAS status in colon cancer has been established. However, their effect on conditional overall survival (COS) remains unknown. METHODS: COS is the probability of surviving additional years after a time from diagnosis. The National Cancer Database (2010-2017) was queried for adults with non-metastatic colon cancer and known mutation status undergoing curative resection. COS was investigated at 2 years. RESULTS: Of 4838 patients, 3716 survived at least 2 years: 15% had stage I, 38% stage II, and 46% stage III disease. Fifty-nine percent had a right-sided tumor, 16% were MSI-high, and 37% were mutated KRAS (mKRAS). The proportion of patients alive at 2 years was higher for stage I compared with stage II and III (65 vs. 61 vs. 54%). The 5-year overall survival for stage I-III was 80, 76, and 67% for the initial cohort, and 90, 88, and 86% for those alive at 2 years. After adjustment, higher pathologic T and N stage, tumor deposits, and no chemotherapy were associated with worse COS (p < 0.01). While laterality and MSI status were not associated with COS, mKRAS was independently associated with decreased COS (HR 1.35, 95% CI 1.12-1.62). CONCLUSION: Patients with mKRAS had worse COS, suggesting that these mutations confer an aggressive biologic behavior, with patients remaining at higher risk of death 2 years after diagnosis. Routine evaluation of KRAS status should be considered in patients with non-metastatic disease for prognostication and to identify those who might benefit from modified surveillance protocols.

The Role of Tumor Location on Endoscopic and Surgical Management of Malignant Colon Polyps.

BACKGROUND: Endoscopic polypectomy could be an appropriate, definitive treatment for pathologic T1 (pT1) colon polyps without high-risk features. Prior studies suggested worse prognosis for proximal versus distal advanced-stage colon cancers following curative treatment. However, there is limited evidence on the prognostic impact of tumor location for pT1s. PATIENTS AND METHODS: This was a retrospective cohort study using the Surveillance, Epidemiology, and End Results database to identify adults with T1NxMx or T1N0-3M0/x colon adenocarcinoma from 2000 to 2019. RESULTS: A total of 3398 patients underwent endoscopic polypectomy (17% proximal) and 28,334 had a partial colectomy (49% proximal) for pT1 adenocarcinoma. Following endoscopic polypectomy, 5-year overall and cancer-specific survival rates were 64% and 91% for proximal versus 83% and 96% for distal polyps, compared with 82% and 95% for proximal versus 88% and 97% for distal tumors after colectomy. In multivariable models, there was a greater difference in overall survival between proximal and distal polyps for those who underwent endoscopic versus surgical resection [hazard ratio (HR) 1.73, 95% confidence interval (CI) 1.49-2.02 vs. HR 1.13, 95% CI 1.08-1.18]. Patients with proximal versus distal polyps who underwent polypectomy also exhibited increased cancer-specific mortality (HR 1.94, 95% CI 1.37-2.75). However, cancer-specific survival variations based on tumor location were no longer observed in patients undergoing partial colectomy (HR 1.09, 95% CI 0.98-1.21). CONCLUSIONS: Proximal tumor location was independently associated with worse overall and cancer-specific survival following endoscopic polypectomy. However, after colectomy, the cancer-specific disparity based on tumor laterality was mitigated. These findings suggest that proximal location may be considered a high-risk feature in endoscopic polypectomy.

Size-Increased All-Phenylene Molecular Spoked Wheels - A Combined Theoretical and Experimental Approach.

A lateral expansion of molecular spoked wheels (MSWs) based on an all-phenylene backbone is described. The MSWs contain a central hub, six spokes and a rim that is formed by a sixfold Yamamoto coupling of the respective non-cyclized dodecabromo precursor yielding MSWs with up to 30 phenylene rings in the perimeter. Attempts to prepare compounds of such size without flexible side groups at the spokes were unsuccessful, most probably due to an aggregation and accompanying oligomerization of the precursors during the cyclization. To overcome these problems, fluorene units are inserted into the spokes. These contain additional alkyl chains and lead to a curvature of the wheels. Quantum chemical calculations on the mechanism of the Yamamoto coupling leads to geometry and strain-related criteria for the successful rim closure to the respective MSW. Subsequently, MSWs are prepared with four and even six phenylene units at each edge of the hexagonal wheels. The resulting MSWs are characterized by spectroscopic methods, and additionally some of them are visualized via scanning tunneling microscopy (STM).

Management and staging of anal adenocarcinoma in the United States: a population-based analysis.

BACKGROUND: Anal adenocarcinoma is rare with no standardized treatment regimen or staging system. Therefore, different combinations of chemotherapy, radiation, and surgery are used in management. Within the staging system, tumor stage can be based on the depth of invasion, as for rectal adenocarcinoma, or size, as in anal squamous cell carcinoma. This study aimed to analyze patterns of care and clinically available staging systems for anal adenocarcinoma using a national database. METHODS: Adults diagnosed with anal adenocarcinoma were identified in the Surveillance, Epidemiology, and End Results database (2004-2019). In addition, 6 different treatment regimens were identified. Stages were categorized according to the American Joint Committee on Cancer classifications of rectal adenocarcinoma and anal squamous cell carcinoma. RESULTS: Of 1040 patients, 48% were female, the median age was 67 years, and 18% had distant metastases. Chemoradiotherapy + abdominoperineal resection was the most common treatment regimen (22%). Moreover, 5-year overall survival (OS) and disease-specific survival (DSS) were the highest for local excision only (67% and 85%) and the lowest in the alternative group (34% and 48%). After adjustment, the treatment groups that did not include surgery were associated with worse 5-year OS. In multivariable analysis, the T stage based on depth of invasion showed incrementally lower OS for T2 and T3 anal adenocarcinomas. CONCLUSION: Omission of surgical resection in combination with chemoradiotherapy was associated with worse OS and DSS, suggesting the relevance of surgery in anal adenocarcinoma management. Prognostically, rectal staging based on depth of invasion better discriminated between T stages, indicating that providers should consider using this system in practice.

A population-based analysis on the incidence of metachronous colon cancer after endoscopic resection of advanced adenomas with high-grade dysplasia: does location matter?

BACKGROUND: Advanced adenomas (AAs) with high-grade dysplasia (HGD) represent a risk factor for metachronous neoplasia, with guidelines recommending short-interval surveillance. Although the worse prognosis of proximal (vs distal) colon cancers (CCs) is established, there is paucity of evidence on the impact of laterality on the risk of subsequent neoplasia for these AAs. METHODS: Adults with HGD adenomas undergoing polypectomy were identified in the Surveillance, Epidemiology, and End Results database (2000-2019). Cumulative incidence of malignancy was estimated using the Kaplan-Meier method. Fine-Gray models assessed the effect of patient and disease characteristics on CC incidence. RESULTS: Of 3199 patients, 26% had proximal AAs. A total of 65 cases of metachronous adenocarcinoma were identified after polypectomy of 35 proximal and 30 distal adenomas with HGD. The 10-year cumulative incidence of CC was 2.3%; when stratified by location, it was 4.8% for proximal vs 1.4% for distal adenomas. Proximal location was significantly associated with increased incidence of metachronous cancer (adjusted hazard ratio, 3.32; 95% CI, 2.05-5.38). CONCLUSION: Proximal location of AAs with HGD was associated with >3-fold increased incidence of metachronous CC and shorter time to diagnosis. These data suggest laterality should be considered in the treatment and follow-up of these patients.