Quantum Hall effect in hydrogenated graphene.

The quantum Hall effect is observed in a two-dimensional electron gas formed in millimeter-scale hydrogenated graphene, with a mobility less than 10 cm2/V·s and corresponding Ioffe-Regel disorder parameter (k(F)λ)(-1) ≫ 1. In a zero magnetic field and low temperatures, the hydrogenated graphene is insulating with a two-point resistance of the order of 250h/e2. The application of a strong magnetic field generates a negative colossal magnetoresistance, with the two-point resistance saturating within 0.5% of h/2e2 at 45 T. Our observations are consistent with the opening of an impurity-induced gap in the density of states of graphene. The interplay between electron localization by defect scattering and magnetic confinement in two-dimensional atomic crystals is discussed.

Ureteric embolization for lower urinary tract fistulae: use of two amplatzer vascular plugs and N-butyl cyanoacrylate employing the "sandwich" technique.

PURPOSE: This study describes and evaluated the effectiveness of occluding distal ureters in the clinical setting of urinary vaginal (vesicovaginal or enterovesicovaginal) fistulae utilizing a new technique which combines Amplatzer vascular plugs and N-butyl cyanoacrylate. MATERIALS: This is a retrospective study (January 2007-December 2010) of patients with urinary-vaginal fistulae undergoing distal ureter embolization utilizing an Amplatzer-N-butyl cyanoacrylate-Amplatzer sandwich technique. An 8-12-mm type-I or type-II Amplatzer vascular plug was delivered using the sheath and deployed in the ureter distal to the pelvic brim. Instillation of 0.8-1.5 cc of N-butyl cyanoacrylate into ureter proximal to the Amplatzer plug was performed. This was followed by another set of 8-12-mm type-I or type-II Amplatzer vascular plugs in a technique referred to as the "sandwich technique." RESULTS: Five ureters in three patients were occluded utilizing the above-described technique during the 4-year study period. Mean maximum size Amplatzer used per ureter was 10.8 mm (range, 8-12). One ureter required three Amplatzer plugs and the rest required two. Two patients (3 ureters) were clinically successful with complete resolution of symptoms in 36-48 h. The third patient (2 ureters) was partly successful and required a second Amplatzer-N-butyl cyanoacrylate sandwich technique embolization. The mean clinical follow-up was 11.3 months (range, 1.7-29.2). CONCLUSIONS: The Amplatzer-N-butyl cyanoacrylate-Amplatzer sandwich technique for occluding the distal ureter is safe and effective with a quick (probably due to the N-butyl cyanoacrylate) and durable (probably due to the Amplatzer plugs) clinical response.

Rheolytic Thrombectomy with or without Adjunctive Indwelling Pharmacolysis in Patients Presenting with Acute Pulmonary Embolism Presenting with Right Heart Strain and/or Pulseless Electrical Activity.

Purpose. To evaluate the safety and efficacy of the Possis rheolytic thrombectomy with or without indwelling catheter-directed pharmacolysis for the treatment of massive pulmonary embolus in patients presenting with right heart strain and/or a pulseless electrical activity (PEA). Materials and Methods. Retrospective review of patients undergoing pulmonary pharmacolysis was performed (07/2004-06/2009). Pre- and posttreatment Miller index scoring weres calculated and compared. Patients were evaluated for tPA doses, ICU stay, hospital stay, and survival by Kaplan-Meier analysis. Results. 11 patients with massive PE were found, with 10/11 presenting with a Miller score of >17 (range: 16-27, mean: 23.2). CTPA and/or echocardiographic evidence of right heart strain was found in 10/11 patients. 3 (27%) patients presented with a PEA event. Two (18%) patients had a contraindication to pharmacolysis and were treated with mechanical thrombectomy alone. The intraprocedural mortality was 9% (n = 1/11). Of the 10 patients who survived the initial treatment, 7 patients underwent standard mechanical thrombectomy initially, while 5 received power pulse spray mechanical thrombectomy. Eight of these 10 patients underwent adjunctive indwelling catheter-directed thrombolysis. The mean catheter-directed infusion duration was 18 hours (range of 12-26 hours). The average intraprocedural, infusion, and total doses of tPA were 7 mg, 19.7 mg, and 26.7 mg, respectively. There was a 91% (10/11) technical success rate. The failure was the single mortality. Average reduction in Miller score was 9.5 or 41% (P = 0.009), obstructive index of 6.4 or 47% (P = 0.03), and perfusion index of 2.7 or 28% (P = 0.05). Average ICU and hospital stay were 7.4 days (range 2-27 days) and 21.3 days (range 6-60 days), respectively. Intent to treat survival was 90% at 6, 12, and 18 months. Conclusion. Rheolytic thrombectomy with or without adjunctive catheter-directed thrombolysis provides a safe and effective method for treatment of acute PE in patients who present with right heart strain and/or a PEA event.

Endovascular therapy for patients with renal angiomyolipoma presenting with retroperitoneal haemorrhage.

We report our experience treating four patients with acutely bleeding angiomyolipoma (AML) of sizes between 4 and 12 cm who were managed with endovascular embolisation with a mean follow-up of 10 months. In our case series, we demonstrate that endovascular embolisation in the acute setting for bleeding AMLs is a viable treatment option. AML should be in the differential diagnosis of acutely bleeding renal masses, even when there is no fat assessed by computed tomography (CT) imaging in the renal mass.