Orbital Complexity in Intrinsic Magnetic Topological Insulators MnBi_{4}Te_{7} and MnBi_{6}Te_{10}.

Using angle-resolved photoelectron spectroscopy (ARPES), we investigate the surface electronic structure of the magnetic van der Waals compounds MnBi_{4}Te_{7} and MnBi_{6}Te_{10}, the n=1 and 2 members of a modular (Bi_{2}Te_{3})_{n}(MnBi_{2}Te_{4}) series, which have attracted recent interest as intrinsic magnetic topological insulators. Combining circular dichroic, spin-resolved and photon-energy-dependent ARPES measurements with calculations based on density functional theory, we unveil complex momentum-dependent orbital and spin textures in the surface electronic structure and disentangle topological from trivial surface bands. We find that the Dirac-cone dispersion of the topologial surface state is strongly perturbed by hybridization with valence-band states for Bi_{2}Te_{3}-terminated surfaces but remains preserved for MnBi_{2}Te_{4}-terminated surfaces. Our results firmly establish the topologically nontrivial nature of these magnetic van der Waals materials and indicate that the possibility of realizing a quantized anomalous Hall conductivity depends on surface termination.

Biopsy-derived oral keratinocytes - A model to potentially test for oral mucosa radiation sensitivity.

Purpose: To establish stable in vitro growth of keratinocytes from very small biopsy specimens and successfully apply new test systems to determine their radiosensitivity. Materials and Methods: Oral mucosa biopsies (diameter: 1.7 mm) from 15 subjects were immobilized with custom-made cups onto culture plates. Outgrowing cells were tested for cytokeratin 5/14 and Ki67, expanded, radiated at different doses, and seeded onto circumscribed areas before being allowed to spread centrifugally. In this newly developed spreading assay, cell-covered areas were measured by image analysis. For statistical analysis, a linear mixed regression model was used; additionally, results were correlated to the radiation dose applied. Colony forming efficiency (CFE) was used to validate the results. DNA damage repair was analysed by gammaH2AX and 53BP1 foci quantification using immunofluorescence microscopy 24 h and 96 h after irradiation. Results: Stable keratinocyte growth continued for up to 7 weeks in 14 biopsies. Cells spread reliably from an initial 16.6 mm2 up to a median of 119.2 mm2 (range: 54.4-290). Radiated cells spread to only 100.7 mm2 (2 Gy; range: 55.3-266.7); 73.2 mm2 (4 Gy; 15-240.4); 47 mm2 (6 Gy; 2-111.9), and 22.7 mm2 (8 Gy; 0-80). Similarly, CFE decreased from 0.223 (0 Gy) to 0.0028 (8 Gy). Using an individual donor as a random factor, cell spread correlated with CFE, where radiation dose was the main driver (decrease by 0.50, adjusted for area). Upon irradiation with 6 Gy, radiation-induced DNA damage was increased after 24 h in all samples, and even after 96 h in 5 out of 7 samples, as detected by a higher number of gammaH2AX/53BP1 foci in irradiated cells (mean 3.7 for 24 h; mean 0.6 for 96 h). Conclusion: In vitro propagation of keratinocytes derived from a small biopsy is feasible. Radiation impairs cellular migration and proliferation, and the newly described spreading assay allows ranking for cellular radioresistance. The keratinocyte model also supports classical functional assays such as clonogenic survival and DNA double strand repair. The clinical relevance awaits upcoming investigations.

Kink far below the Fermi level reveals new electron-magnon scattering channel in Fe.

Many properties of real materials can be modeled using ab initio methods within a single-particle picture. However, for an accurate theoretical treatment of excited states, it is necessary to describe electron-electron correlations including interactions with bosons: phonons, plasmons, or magnons. In this work, by comparing spin- and momentum-resolved photoemission spectroscopy measurements to many-body calculations carried out with a newly developed first-principles method, we show that a kink in the electronic band dispersion of a ferromagnetic material can occur at much deeper binding energies than expected (Eb = 1.5 eV). We demonstrate that the observed spectral signature reflects the formation of a many-body state that includes a photohole bound to a coherent superposition of renormalized spin-flip excitations. The existence of such a many-body state sheds new light on the physics of the electron-magnon interaction which is essential in fields such as spintronics and Fe-based superconductivity.

Endoscopic sphincterotomy permits interval laparoscopic cholecystectomy in patients with moderately severe gallstone pancreatitis.

Patients with moderately severe gallstone pancreatitis with substantial pancreatic and peripancreatic inflammation, but without organ failure, frequently have an open cholecystectomy to prevent recurrent pancreatitis. In these patients, prophylactic endoscopic retrograde cholangiography (ERC) with endoscopic sphincterotomy (ES) may prevent recurrent pancreatitis, permit laparoscopic cholecystectomy, and decrease risks. The medical records of all patients with pancreatitis undergoing cholecystectomy from 1999-2004 at the University of North Carolina Memorial Hospital were reviewed. Data regarding demographics, clinical course, etiology of pancreatitis, operative and endoscopic interventions, and outcome were extracted. Moderately severe gallstone-induced pancreatitis was defined as pancreatitis without organ failure but with extensive local inflammation. Thirty patients with moderately severe gallstone pancreatitis underwent ERC and ES and were discharged before cholecystectomy. Mean interval between ES and cholecystectomy was 102 +/- 17 days. Cholecystectomy was performed laparoscopically in 27 (90%) patients, open in three (10%) patients, and converted to open in two (7%) patients, with a morbidity rate of 7% (two patients). No patient required drainage of a pseudocyst or developed recurrent pancreatitis. Interval complications resulted in hospital readmission in seven (23%) patients. In conclusion, recurrent biliary pancreatitis in patients with moderately severe gallstone pancreatitis is nil after ERC and ES. Hospital discharge of these patients permits interval laparoscopic cholecystectomy, but close follow-up is necessary in these potentially ill patients.

Fundoplication improves disordered esophageal motility.

Patients with gastroesophageal reflux disease (GERD) and disordered esophageal motility are at risk for postoperative dysphagia, and are often treated with partial (270-degree) fundoplication as a strategy to minimize postoperative swallowing difficulties. Complete (360-degree) fundoplication, however, may provide more effective and durable reflux protection over time. Recently we reported that postfundoplication dysphagia is uncommon, regardless of preoperative manometric status and type of fundoplication. To determine whether esophageal function improves after fundoplication, we measured postoperative motility in patients in whom disordered esophageal motility had been documented before fundoplication. Forty-eight of 262 patients who underwent laparoscopic fundoplication between 1995 and 2000 satisfied preoperative manometric criteria for disordered esophageal motility (distal esophageal peristaltic amplitude < or =30 mm Hg and/or peristaltic frequency < or =80%). Of these, 19 had preoperative manometric assessment at our facility and consented to repeat study. Fifteen (79%) of these patients had a complete fundoplication and four (21%) had a partial fundoplication. Each patient underwent repeat four-channel esophageal manometry 29.5 +/- 18.4 months (mean +/- SD) after fundoplication. Distal esophageal peristaltic amplitude and peristaltic frequency were compared to preoperative data by paired t test. After fundoplication, mean peristaltic amplitude in the distal esophagus increased by 47% (56.8 +/- 30.9 mm Hg to 83.5 +/- 36.5 mm Hg; P < 0.001) and peristaltic frequency improved by 33% (66.4 +/- 28.7% to 87.6 +/- 16.3%; P < 0.01). Normal esophageal motor function was present in 14 patients (74%) after fundoplication, whereas in five patients the esophageal motor function remained abnormal (2 improved, 1 worsened, and 2 remained unchanged). Three patients with preoperative peristaltic frequencies of 0%, 10%, and 20% improved to 84%, 88%, and 50%, respectively, after fundoplication. In most GERD patients with esophageal dysmotility, fundoplication improves the amplitude and frequency of esophageal peristalsis, suggesting refluxate has an etiologic role in motor dysfunction. These data, along with prior data showing that postoperative dysphagia is not common, imply that surgeons should apply complete fundoplication liberally in patients with disordered preoperative esophageal motility.

Complete fundoplication is not associated with increased dysphagia in patients with abnormal esophageal motility.

Abnormal esophageal motility is a relative contraindication to complete (360-degree) fundoplication because of a purported risk of postoperative dysphagia. Partial fundoplication, however, may be associated with increased postoperative esophageal acid exposure. Our aim was to determine if complete fundoplication is associated with increased postoperative dysphagia in patients with abnormal esophageal motor function. Medical records of 140 patients (79 females; mean age 48 +/- 1.1 years) who underwent fundoplication for gastroesophageal reflux disease (GERD) were reviewed retrospectively to document demographic data, symptoms, and diagnostic test results. Of the 126 patients who underwent complete fundoplication, 25 met manometric criteria for abnormal esophageal motility (#30 mm Hg mean distal esophageal body pressure or #80% peristalsis), 68 had normal esophageal function, and 33 had incomplete manometric data and were therefore excluded from analysis. Of the 11 patients who underwent partial fundoplication, eight met criteria for abnormal esophageal motility, two had normal esophageal function, and one had incomplete data and was therefore excluded. After a median follow-up of 2 years (range 0.5 to 5 years), patients were asked to report heartburn, difficulty swallowing, and overall satisfaction using a standardized scoring scale. Complete responses were obtained in 72%. Sixty-five patients who underwent complete fundoplication and had manometric data available responded (46 normal manometry; 19 abnormal manometry). Outcomes were compared using the Mann-Whitney U test. After complete fundoplication, similar postoperative heartburn, swallowing, and overall satisfaction were reported by patients with normal and abnormal esophageal motility. Likewise, similar outcomes were reported after partial fundoplication. This retrospective study found equally low dysphagia rates regardless of baseline esophageal motility; therefore a randomized trial comparing complete versus partial fundoplication in patients with abnormal esophageal motility is warranted.

Acute vagotomy does not augment the systemic inflammatory response in patients with peptic ulcer disease.

Recent accumulating evidence suggests that the vagus nerve modulates the response to peripheral immunologic stimuli and that intact vagal mediation decreases the systemic inflammatory response. We hypothesized that patients who had vagotomy for complicated peptic ulcer disease would be at increased risk of an enhanced systemic inflammatory response compared to patients that did not have a vagotomy as part of their operative treatment. Ninety-six patients were identified from 1985 to 2000 and their medical records were reviewed. Patients were assigned to three groups based on the performance of a truncal vagotomy: truncal vagotomy (TV; N = 62 patients), nontruncal vagotomy (NTV; N = 34 patients), or a subgroup of the TV group, acute truncal vagotomy (ATV; N = 40 patients). Operative indications in the NTV and ATV groups were perforation (94% vs 47%) and bleeding (6% vs 53%). Systemic or organ-specific complications did not differ between groups (NTV vs ATV), and the sepsis (24% vs 23%) and mortality rates (29% vs 20%) were similar. The ICU and hospital length of stay did not differ substantially among the groups. This clinical study demonstrated that acute truncal vagotomy does not increase the risk of the systemic inflammatory response in surgical patients with complicated peptic ulcer disease.

Eczema mimicking child abuse: a case of mistaken identity.

Many skin conditions can mimic child abuse by burning. Multidisciplinary evaluation of suspicious burns helps prevent both the underreporting and the misdiagnosis of child abuse by burning. We report a case of pediatric eczema mimicking an abusive burn.

Ski promotes tumor growth through abrogation of transforming growth factor-beta signaling in pancreatic cancer.

OBJECTIVE: We hypothesized that human pancreatic cancer resists TGF-beta signaling and cell death through increased Ski expression. SUMMARY BACKGROUND DATA: Ski is an oncogenic protein that acts as a TGF-beta repressor and prevents related gene transcription. Previous work suggests that Ski acts as an oncoprotein in melanoma and esophageal cancer. Ski expression and function have not been determined in human pancreatic cancer. METHODS: Immunohistochemistry and immunoblots assessed Ski expression in human pancreatic cancer. Panc-1 cells were treated with or without Ski siRNA, and Ski and Smad protein expression, transcriptional reporter activation, and growth assays were determined. Panc-1 cells were inoculated in the flank of nude mice and tumor volume and histology assessed after administration of Ski siRNA or control vector. RESULTS: Ski was abundantly expressed in human pancreatic cancer specimens assessed by immunohistochemistry (91%) and immunoblot analysis (67%). Panc-1 cells exhibited nascent Ski expression that was maximally inhibited 48 hours after transfection with Ski siRNA. TGF-beta transcriptional activity was increased 2.5-fold in Ski siRNA-treated cells compared with control (P < 0.05). Ski siRNA increased TGF-beta-induced Smad2 phosphorylation and p21 expression. Panc-1 growth in culture was decreased 2-fold at 72 hours. A Ski siRNA expression vector injected into nude mice resulted in a 5-fold decrease in growth. CONCLUSION: Inhibition of Ski through RNA interference restored TGF-beta signaling and growth inhibition in vitro, and decreased tumor growth in vivo.

The natural history of pancreatitis-induced splenic vein thrombosis.

OBJECTIVE: To determine the natural history of pancreatitis-induced splenic vein thrombosis with particular attention to the risk of gastric variceal hemorrhage. SUMMARY BACKGROUND DATA: Previous studies have suggested that splenic vein thrombosis results in a high likelihood of gastric variceal bleeding and that splenectomy should be performed to prevent hemorrhage. Recent improvements in cross-sectional imaging have led to the identification of splenic vein thrombosis in patients with minimal symptoms. Our clinical experience suggested that gastric variceal bleeding in these patients was uncommon. METHODS: A computerized index search from 1993 to 2002 for the medical records of patients with a diagnosis of pancreatitis was performed. Fifty-three patients with a diagnosis of pancreatitis and splenic vein thrombosis were identified. The medical records of these patients were reviewed, and follow-up was completed, including the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC-QLQ). RESULTS: Gastrosplenic varices were identified in 41 patients (77%) with varices evident on computed tomography (CT) in 40 of 53 patients, on esophagogastroduodenoscopy (EGD) in 11 of 36 patients, and on both CT and EGD in 10 of 36 patients. This risk of variceal bleeding was 5% for patients with CT-identified varices and 18% for EGD-identified varices. Overall, only 2 patients (4%) had gastric variceal bleeding and required splenectomy. Functional quality of life was better than historical controls surgically treated for chronic pancreatitis. CONCLUSION: Gastric variceal bleeding from pancreatitis-induced splenic vein thrombosis occurs in only 4% of patients; therefore, routine splenectomy is not recommended.