Triskelion Structured Colloidal Quantum Dots.

We show, using density functional theory and ab initio molecular dynamics, that certain small colloidal quantum dots with a mixed nanocrystal core capped with achiral surface ligands spontaneously form a triskelion (from the Greek, three-legged) structure with (approximate) C3 symmetry that can be dynamically stable at room temperature when additionally capped with small amine ligands. Furthermore, the nanocrystal core also forms a triskelion structure. The focus of our study is a colloidal quantum dot with a Cd16Se7Te3 core (and a charge of +12) capped with negatively charged surface ligands to achieve charge neutrality-in the simplest instance, 12 Cl--to form the colloidal quantum dot Cd16Se7Te3Cl12. The small size of the core (for which almost all atoms are surface atoms), the high positive charge that destabilizes the core, the mixed (Cd/Te) composition that creates mechanical strain in the core, and the inclusion of precisely three Te atoms in the predominantly Se core all play critical roles in the spontaneous formation of the triskelion structure.

Critical lower-limb ischemia: the diagnostic performance of dual-phase injection MR angiography (including high-resolution distal imaging) compared with digital subtraction angiography.

PURPOSE: To prospectively compare contrast-enhanced (CE) magnetic resonance (MR) angiography against digital subtraction angiography (DSA) in patients with critical lower-limb ischemia. MATERIALS AND METHODS: Thirty patients with critical lower limb ischemia underwent both CE MR angiography and DSA. CE MR angiography commenced with a dedicated high-resolution study of the below-knee arteries followed by a three-station bolus-chase examination. Two blinded observers recorded the severity of the most significant stenosis within each arterial segment. Interobserver agreement was calculated and, with DSA as the reference standard, the sensitivity and specificity of CE MR angiography for the detection of significant stenosis (>or=50% luminal narrowing) or occlusion was calculated. RESULTS: All 390 arterial segments were scored by both observers. Sensitivity was higher in the distal segments (92%-96%) compared with the proximal segments (69%-79%). Specificity was similar in distal (90%-91%) and more proximal segments (86%-96%). Overall, interobserver agreement was excellent (kappa = 0.95 for CE MR angiography and DSA) and was superior within the distal segments. Twenty-eight segments that were considered occluded on DSA were shown to be patent on CE MR angiography and 16 segments that were considered occluded on CE MR angiography were shown to be patent on DSA. CONCLUSIONS: In patients with critical lower-limb ischemia, CE MR angiography with high-resolution distal imaging is highly accurate for assessment of the below-knee arteries. Both DSA and CE MR angiography may identify patent vessels that are considered occluded based on the other modality.

Uterine-artery embolization versus surgery for symptomatic uterine fibroids.

BACKGROUND: The efficacy and safety of uterine-artery embolization, as compared with standard surgical methods, for the treatment of symptomatic uterine fibroids remain uncertain. METHODS: We conducted a randomized trial comparing uterine-artery embolization and surgery in women with symptomatic uterine fibroids. The primary outcome was quality of life at 1 year of follow-up, as measured by the Medical Outcomes Study 36-Item Short-Form General Health Survey (SF-36). RESULTS: Patients were randomly assigned in a 2:1 ratio to undergo either uterine-artery embolization or surgery, with 106 patients undergoing embolization and 51 undergoing surgery (43 hysterectomies and 8 myomectomies). There were no significant differences between groups in any of the eight components of the SF-36 scores at 1 year. The embolization group had a shorter median duration of hospitalization than the surgical group (1 day vs. 5 days, P<0.001) and a shorter time before returning to work (P<0.001). At 1 year, symptom scores were better in the surgical group (P=0.03). During the first year of follow-up, there were 13 major adverse events in the embolization group (12%) and 10 in the surgical group (20%) (P=0.22), mostly related to the intervention. Ten patients in the embolization group (9%) required repeated embolization or hysterectomy for inadequate symptom control. After the first year of follow-up, 14 women in the embolization group (13%) required hospitalization, 3 of them for major adverse events and 11 for reintervention for treatment failure. CONCLUSIONS: In women with symptomatic fibroids, the faster recovery after embolization must be weighed against the need for further treatment in a minority of patients. (ISRCTN.org number, ISRCTN23023665 [controlled-trials.com].)

Bronchopleural fistula treated with a covered wallstent.

Bronchopleural fistula is a well-recognized complication of pneumonectomy, which presents a difficult challenge to the thoracic surgeon. We report the successful treatment of a bronchopleural fistula after right pneumonectomy for lung cancer, using a covered esophageal stent.

Results of a retrospective multicenter trial of the Viatorr expanded polytetrafluoroethylene-covered stent-graft for transjugular intrahepatic portosystemic shunt creation.

PURPOSE: To report the results of a multicenter experience with the Viatorr expanded polytetrafluoroethylene-covered stent-graft for transjugular intrahepatic portosystemic shunt (TIPS) creation in which patency and clinical outcome were evaluated. MATERIALS AND METHODS: One hundred consecutive patients with portal hypertension, with a mean age of 52 years (range, 22-86 years), underwent implantation of the Viatorr TIPS stent-graft at one of three hospital centers. The indications for TIPS creation were variceal bleeding (n = 81) and refractory ascites (n = 19). Twenty patients had Child-Pugh class A disease, 46 had class B disease, and 34 had class C disease. Eighty-seven patients underwent de novo TIPS placements, with 13 treated for recurrent TIPS stenosis. Sixty-two patients were available for follow-up portal venography and portosystemic pressure gradient (PSG) measurement commencing 6 months after Viatorr stent-graft placement. RESULTS: The technical success rate was 100%. TIPS creation resulted in an immediate decrease in mean PSG (+/-SD) from 21 mm Hg +/- 6 to 7 mm Hg +/- 3. Acute repeat intervention (within 30 days) was required for portal vein thrombosis (n = 1), continued bleeding (n = 3), and encephalopathy (n = 1). The all-cause 30-day mortality rate was 12%. Two patients developed acute severe refractory encephalopathy, which led to death in one case. New or worsening encephalopathy was identified in 14% of patients. The incidence of recurrent bleeding was 8%. The cumulative survival rate at 1 year was 65%. Sixty-two patients available for venographic follow-up had a mean PSG of 9 mm Hg +/- 5 at a mean interval of 343 days (range, 56-967 days). There were four stent-graft occlusions (6%) and seven hemodynamically significant stenoses (11%), four within the stent-graft and three in the non-stent-implanted hepatic vein. The primary patency rate at 1 year by Kaplan-Meier analysis was 84%. CONCLUSIONS: This retrospective multicenter experience with the Viatorr stent-graft confirms the preliminary findings of other investigators of good technical results and improved patency compared with bare stents. Early mortality and symptomatic recurrence rates are low by historical standards. The theoretical increase in TIPS-related encephalopathy was not demonstrated. Longer-term follow-up will be required to determine whether the additional cost of the Viatorr stent-graft will be offset by reduced surveillance and repeat intervention.