Adjuvant therapy in primary GIST: state-of-the-art.

BACKGROUND: The management of primary gastrointestinal stromal tumours (GISTs) has evolved with the introduction of adjuvant therapy. Recently reported results of the SSG XVIII/AIO trial by the Scandinavian Sarcoma Group (SSG) and the German Working Group on Medical Oncology (AIO) represent a significant change in the evidence for adjuvant therapy duration. The objectives of this European Expert Panel meeting were to describe the optimal management and best practice for the systemic adjuvant treatment of patients with primary GISTs. MATERIALS AND METHODS: A panel of medical oncology experts from European sarcoma research groups were invited to a 1-day workshop. Several questions and discussion points were selected by the organising committee prior to the conference. The experts reviewed the current literature of all clinical trials available on adjuvant therapy for primary GISTs, considered the quality evidence and formulated recommendations for each discussion point. RESULTS: Clinical issues were identified and provisional clinical opinions were formulated for adjuvant treatment patient selection, imatinib dose, duration and patient recall, mutational analysis and follow-up of primary GIST patients. Adjuvant imatinib 400 mg/day for 3 years duration is a standard treatment in all patients with significant risk of recurrence following resection of primary GISTs. Patient selection for adjuvant therapy should be based on any of the three commonly used patient risk stratification schemes. R1 surgery (versus R0) alone is not an indication for adjuvant imatinib in low-risk GIST. Recall and imatinib restart could be proposed in patients who discontinued 1-year adjuvant imatinib within the previous 3 months and may be considered on a case-by-case basis in patients who discontinued within the previous year. Mutational analysis is recommended in all cases of GISTs using centralised laboratories with good quality control. Treatment is not recommended in an imatinib-insensitive D842V-mutated GIST. During adjuvant treatment, patients are recommended to be clinically assessed at 1- to 3-month intervals. Upon discontinuation, computed tomography scan (CT) scans are recommended every 3 to 4 months for 2 years when the risk of relapse is highest, followed by every 6 months until year 5 and annually until year 10 after treatment discontinuation. CONCLUSIONS: Key points in systemic adjuvant treatment and clinical management of primary GISTs as well as open questions were identified during this European Expert Panel meeting on GIST management.

Magnetoresistance of rolled-up Fe3Si nanomembranes.

Magnetotransport of individual rolled-up Fe(3)Si nanomembranes is investigated in a broad temperature range from 4.2 K up to 300 K in pulsed magnetic fields up to 55 T. The observed magnetoresistance (MR) has the following pronounced features: (i) MR is negative in the investigated intervals of temperature and magnetic field; (ii) its magnitude increases linearly with the magnetic field in a low-field region and reveals a gradual trend to saturation when the magnetic field increases; (iii) the MR effect becomes more pronounced with increasing temperature. These dependences of MR on the magnetic field and temperature are in line with predictions of the spin-disorder model of the spin-flip s-d interaction assisted with creation or annihilation of magnons, which is expected above a certain critical temperature. Comparison of the MR features in rolled-up and planar samples reveals a substantial increase of the critical temperature in the rolled-up tube, which is attributed to a new geometry and internal strain arising in the rolled-up nanomembranes, influencing the electronic and magnetic properties of the material.

Thermodynamic properties and neutron diffraction studies of silver ferrite AgFeO2.

We present thermodynamic and neutron scattering data on silver ferrite AgFeO(2). The data imply that strong magnetic frustration Θ/T(N)∼10 and magnetic ordering arise via two successive phase transitions at T(2) = 7 K and T(1) = 16 K. At T

High mobility in LaAlO3/SrTiO3 heterostructures: origin, dimensionality, and perspectives.

We have investigated the dimensionality and origin of the magnetotransport properties of LaAlO3 films epitaxially grown on TiO2-terminated SrTiO3(001) substrates. High-mobility conduction is observed at low deposition oxygen pressures (P(O2)<10(-5) mbar) and has a three-dimensional character. However, at higher P(O2) the conduction is dramatically suppressed and nonmetallic behavior appears. Experimental data strongly support an interpretation of these properties based on the creation of oxygen vacancies in the SrTiO3 substrates during the growth of the LaAlO3 layer. When grown on SrTiO3 substrates at low P(O2), other oxides generate the same high mobility as LaAlO3 films. This opens interesting prospects for all-oxide electronics.

Aharonov-Bohm conductance modulation in ballistic carbon nanotubes.

We report on magnetoconductance experiments in ballistic multiwalled carbon nanotubes threaded by magnetic fields as large as 55 T. In the high temperature regime (100 K), giant modulations of the conductance, mediated by the Fermi level location, are unveiled. The experimental data are consistently analyzed in terms of the field-dependent density of states of the external shell that modulates the injection properties at the electrode-nanotube interface, and the resulting linear conductance. This is the first unambiguous experimental evidence of Aharonov-Bohm effect in clean multiwalled carbon nanotubes.

Anal canal duplication: a retrospective analysis of 12 cases from two European pediatric surgical departments.

Anal canal duplication (ACD) represents an extremely rare intestinal congenital anomaly of unknown origin. Usually evidenced within 2 years of age, nearly 45% of reported cases present associated malformations such as presacral mass, anorectal malformation (ARM) and genitourinary anomalies. The confirmative diagnosis is histopathological, with evidence of an anal mucosal lining (squamous +/- transitional epithelium), surrounded from a smooth muscle coat and anal glands. We review a conjoined experience from two European pediatric surgical departments. From 1970 to 2005, 12 patients were observed, seven in Pescara, Italy (1997-2005), five in Barcelona, Spain (1970-2004) - mean age at diagnosis 17.8 months, range 0-60; M:F = 1:11. Clinical presentation, diagnostic-surgical approach, and complications were reviewed. According to clinical presentation, patients could be divided in three age groups: asymptomatic (mean age 4.8 months, six patients - one with an associated complex genitourinary malformation, one with a presacral mature teratoma, one with ACD evidenced hysthologically on a retroanal mass removed during the correction of an ARM), mildly symptomatic - constipation, mucous discharge (mean age 29.2 months, four patients - one with associated presacral ependymoma and intestinal neuronal dysplasia type B, one with presacral mass) and complicated - perineal abscess, recurrent fistula (mean age 34 months, two patients). In 11 cases a perianal orifice was evident (ten posteriorly located). The pelvic-MRI was the preferred diagnostic tool in Pescara (5/7, with presacral mass in two patients), fistulography in Barcelona (5/5), where one presacral mass was discovered intraoperatively. Eleven patients underwent surgical removal of the ACD (five perineal approach, five posterior sagittal approach, and one PSARP). Histopathological findings confirmed the diagnosis in operated cases (11). The parents of the male patient denied the consent to surgical treatment. The only major post-operative complication was a sphincteric insufficiency (one case), surgically treated. When facing a perianal orifice, attention should be paid to ACD, particularly in female patients with coexistent genitourinary or intestinal malformations. Pelvic US and MRI are the gold standard to evidence the not rarely associated presacral mass. Surgical early removal (mucosectomy or perineal/posterior sagittal approach, depending on length of ACD and associated presacral mass) is warranted, also in asymptomatic patients, because of the risk of inflammatory complications and cancer (the latter reported in literature in adults).

Hopping conductivity in CaCu(2)O(3) single crystals.

The resistivity, ρ, of the spin-ladder compound CaCu(2)O(3) is investigated between T∼130-450 K. The ρ(T) data measured for [Formula: see text] (along the Cu-O-Cu leg) and [Formula: see text] (along the Cu-O-Cu rungs), ρ(a)(T)>ρ(b)(T), exhibit an activated dependence, similar in both directions and characterized by a nearest-neighbour hopping followed by a variable-range hopping (VRH) regime when T is decreased. A detailed analysis of ρ(T) demonstrates that conventional d-dimensional models of the hopping conductivity, based on the electron localization in disordered systems, cannot interpret the experimental data at any d = 1, 2 or 3, leading to the mismatch of the characteristic energies and/or unphysical values of the characteristic length scales. The observed VRH conductivity law on the low-temperature interval, lnρ∼T(-3/4), contradicts the models above, too. Instead, it is found that this law can be substantiated and the correct matching of the energy and length scales can be found within a model of Fogler et al (2004 Phys. Rev. B 69 035413) by treating CaCu(2)O(3) as a three-dimensional array of quasi-one-dimensional electron crystals.

Gate-dependent magnetoresistance phenomena in carbon nanotubes.

We report on the first experimental study of the magnetoresistance of double-walled carbon nanotubes under a magnetic field as large as 50 T. By varying the field orientation with respect to the tube axis, or by gate-mediated shifting the Fermi level position, evidence for unconventional magnetoresistance is presented and interpreted by means of theoretical calculations.

Quantization of the Hall conductivity well beyond the adiabatic limit in pulsed magnetic fields.

We measure the Hall conductivity, sigma(xy), on a Corbino geometry sample of a high-mobility AlGaAs/GaAs heterostructure in a pulsed magnetic field. At a bath temperature about 80 mK, we observe well expressed plateaux in sigma(xy) at integer filling factors. In the pulsed magnetic field, the Laughlin condition of the phase coherence of the electron wave functions is strongly violated and, hence, is not crucial for sigma(xy) quantization.