Field-Induced gap due to four-spin exchange in a spin ladder

The effect of the four-spin cyclic exchange interaction at each plaquette in the $S=1/2$ two-leg spin ladder is investigated at T=0, especially focusing on the field-induced gap. The strong rung coupling approximation suggests that it yields a plateau at half of the saturation moment ($m=1/2$) in the magnetization curve, which corresponds to a field-induced spin gap with a spontaneous breaking of the translational symmetry. A precise phase diagram at $m=1/2$ is also presented based on the level spectroscopy analysis of the numerical data obtained by Lanczos method. The boundary between the gapless and plateau phases is confirmed to be of the Kosterlitz-Thouless (KT) universality class.Comment: 10 pages, 3 eps figures (embedded), to be published in J. Phys.: Cond. Matte

Spontaneous closure of an aggressive non-traumatic dural arteriovenous fistula

Background: We describe a case of a non-traumatic dural arteriovenous fistula (dAVF) with cortical venous reflux (CVR) that closed spontaneously with simultaneous intracerebral hemorrhage. We reviewed the literature to discuss about the mechanism of spontaneous closure and an optimal timing of treatment for aggressive dAVF with benign presentation. Case description: A 71-year-old woman presented with right ocular conjunctival hyperemia and diplopia without history of trauma. The initial digital subtraction angiography (DSA) demonstrated a right cavernous sinus dAVF, Borden type III, with a single feeder of anterior branch of the right middle meningeal artery, shunting at the posterior part of the right cavernous sinus wall, and draining into the right superficial middle cerebral vein, not into the right superior ophthalmic vein. Because of CVR, endovascular therapy was planned. Two months later, she was admitted to our hospital presenting generalized convulsion. CT scan showed a multilobulated hematoma in the right frontal lobe. The control DSA revealed disappearance of the dAVF. She had a cognitive dysfunction as a sequele of hemorrhage. Conclusions: In the literature, spontaneous closures of non-traumatic dAVF with CVR were reported in 21 cases. It may cause neurological sequele as the present case experienced. The mechanism of spontaneous closure is unknown and may include factors to be elucidated. We recommend prompt diagnosis and treatment for patients with dAVF with CVR even if associated with benign onset

The global DNA methylation surrogate LINE-1 methylation is correlated with MGMT promoter methylation and is a better prognostic factor for glioma.

Gliomas are the most frequently occurring primary brain tumor in the central nervous system of adults. Glioblastoma multiformes (GBMs, WHO grade 4) have a dismal prognosis despite the use of the alkylating agent, temozolomide (TMZ), and even low grade gliomas (LGGs, WHO grade 2) eventually transform to malignant secondary GBMs. Although GBM patients benefit from promoter hypermethylation of the O(6)-methylguanine-DNA methyltransferase (MGMT) that is the main determinant of resistance to TMZ, recent studies suggested that MGMT promoter methylation is of prognostic as well as predictive significance for the efficacy of TMZ. Glioma-CpG island methylator phenotype (G-CIMP) in the global genome was shown to be a significant predictor of improved survival in patients with GBM. Collectively, we hypothesized that MGMT promoter methylation might reflect global DNA methylation. Additionally in LGGs, the significance of MGMT promoter methylation is still undetermined. In the current study, we aimed to determine the correlation between clinical, genetic, and epigenetic profiles including LINE-1 and different cancer-related genes and the clinical outcome in newly diagnosed 57 LGG and 54 GBM patients. Here, we demonstrated that (1) IDH1/2 mutation is closely correlated with MGMT promoter methylation and 1p/19q codeletion in LGGs, (2) LINE-1 methylation levels in primary and secondary GBMs are lower than those in LGGs and normal brain tissues, (3) LINE-1 methylation is proportional to MGMT promoter methylation in gliomas, and (4) higher LINE-1 methylation is a favorable prognostic factor in primary GBMs, even compared to MGMT promoter methylation. As a global DNA methylation marker, LINE-1 may be a promising marker in gliomas

JCOG0911 INTEGRA study: a randomized screening phase II trial of interferonβ plus temozolomide in comparison with temozolomide alone for newly diagnosed glioblastoma

Purpose: This study explored the superiority of temozolomide (TMZ) + interferonβ (IFNβ) to standard TMZ as treatment for newly diagnosed glioblastoma (GBM) via randomized phase II screening design.Experimental design: Eligibility criteria included histologically proven GBM, with 50% of the tumor located in supratentorial areas, without involvement of the optic, olfactory nerves, and pituitary gland and without multiple lesions and dissemination. Patients in the TMZ + radiotherapy (RT) arm received RT (2.0 Gy/fr/day, 30 fr) with TMZ (75 mg/m², daily) followed by TMZ maintenance (100–200 mg/m²/day, days 1–5, every 4 weeks) for 2 years. Patients in the TMZ + IFNβ + RT arm intravenously received IFNβ (3 MU/body, alternative days during RT and day 1, every 4 weeks during maintenance period) and TMZ + RT. The primary endpoint was overall survival (OS). The planned sample size was 120 (one-sided alpha 0.2; power 0.8).Results: Between Apr 2010 and Jan 2012, 122 patients were randomized. The median OS with TMZ + RT and TMZ + IFNβ + RT was 20.3 and 24.0 months (HR 1.00, 95% CI 0.65–1.55; one-sided log rank P = 0.51). The median progression-free survival times were 10.1 and 8.5 months (HR 1.25, 95% CI 0.85–1.84). The incidence of neutropenia with the TMZ + RT and the TMZ + IFNβ + RT (grade 3–4, CTCAE version 3.0) was 12.7 versus 20.7% during concomitant period and was 3.6 versus 9.3% during maintenance period. The incidence of lymphopenia was 54.0 versus 63.8% and 34.5 versus 41.9%.Conclusions: TMZ + IFNβ + RT is not considered as a candidate for the following phase III trial, and TMZ + RT remained to be a most promising treatment. This trial was registered with the UMIN Clinical Trials Registry: UMIN000003466