The protein kinase Chk2, the mammalian homolog of the budding yeast Rad53 and fission yeast Cds1 checkpoint kinases, is phosphorylated and activated in response to DNA damage by ionizing radiation (IR), UV irradiation, and replication blocks by hydroxyurea (HU). Phosphorylation and activation of Chk2 are ataxia telangiectasia-mutated (ATM) dependent in response to IR, whereas Chk2 phosphorylation is ATM-independent when cells are exposed to UV or HU. Here we show that in vitro, ATM phosphorylates the Ser-Gln͞Thr-Gln (SQ͞TQ) cluster domain (SCD) on Chk2, which contains seven SQ͞TQ motifs, and Thr68 is the major in vitro phosphorylation site by ATM. ATM-and Rad3-related also phosphorylates Thr68 in addition to Thr26 and Ser50, which are not phosphorylated to a significant extent by ATM in vitro. In vivo, Thr68 is phosphorylated in an ATM-dependent manner in response to IR, but not in response to UV or HU. Substitution of Thr68 with Ala reduced the extent of phosphorylation and activation of Chk2 in response to IR, and mutation of all seven SQ͞TQ motifs blocked all phosphorylation and activation of Chk2 after IR. These results suggest that in vivo, Chk2 is directly phosphorylated by ATM in response to IR and that Chk2 is regulated by phosphorylation of the SCD.

Blister-type and saccular-type aneurysms have different shapes and wall characteristics. The saccular type can be treated by clipping, whereas the blister type requires clipping on wrapping material. ICA trunk aneurysms may be a better designation to express the diversity of these aneurysms, rather than ICA blood blister-like or anterior or dorsal wall aneurysms.

Background and Purpose-About one half of those who develop adult-onset moyamoya disease experience intracranial hemorrhage. Despite the extremely high frequency of rebleeding attacks and poor prognosis, measures to prevent rebleeding have not been established. The purpose of this study is to determine whether extracranial-intracranial bypass can reduce incidence of rebleeding and improve patient prognosis. Methods-This study was a multicentered, prospective, randomized, controlled trial conducted by 22 institutes in Japan.Adult patients with moyamoya disease who had experienced intracranial hemorrhage within the preceding year were given either conservative care or bilateral extracranial-intracranial direct bypass and were observed for 5 years. Primary and secondary end points were defined as all adverse events and rebleeding attacks, respectively. Results-Eighty patients were enrolled (surgical, 42; nonsurgical, 38). Adverse events causing significant morbidity were observed in 6 patients in the surgical group (14.3%) and 13 patients in the nonsurgical group (34.2%). Kaplan-Meier survival analysis revealed significant differences between the 2 groups (3.2%/y versus 8.2%/y; P=0.048). The hazard ratio of the surgical group calculated by Cox regression analysis was 0.391 (95% confidence interval, 0.148-1.029).Rebleeding attacks were observed in 5 patients in the surgical group (11.9%) and 12 in the nonsurgical group (31.6%), significantly different in the Kaplan-Meier survival analysis (2.7%/y versus 7.6%/y; P=0.042). The hazard ratio of the surgical group was 0.355 (95% confidence interval, 0.125-1.009). Conclusions-Although statistically marginal, Kaplan-Meier analysis revealed the significant difference between surgical and nonsurgical group, suggesting the preventive effect of direct bypass against rebleeding. Clinical Trial Registration

Background and Purpose-The Middle Cerebral Artery Embolism Local Fibrinolytic Intervention Trial (MELT) Japan was organized to determine the safety and clinical efficacy of intraarterial infusion of urokinase (UK) in patients with stroke within 6 hours of onset. Methods-Patients with ischemic stroke presenting within 6 hours of onset and displaying occlusions of the M1 or M2 portion of the middle cerebral artery on carotid angiography were randomized to the UK or control groups. Clinical outcome was assessed by the modified Rankin Scale, National Institutes of Health Stroke Scale, and Barthel Index. Results-The Independent Monitoring Committee recommended stopping the trial after approval of intravenous infusion of recombinant tissue plasminogen activator in Japan. A total of 114 patients underwent randomization, 57 patients in each group. Background characteristics were comparable between the 2 groups. The primary end point of favorable outcome (modified Rankin Scale 0 to 2) at 90 days was somewhat more frequent in the UK group than in the control group (49.1% and 38.6%, OR: 1.54, 95% CI: 0.73 to 3.23) but did not reach a significant level (Pϭ0.345). However, excellent functional outcome (modified Rankin Scale 0 to 1) at 90 days, a preplanned secondary end point, was more frequent in the UK group than in the control group (42.1% and 22.8%, Pϭ0.045, OR: 2.46, 95% CI: 1.09 to 5.54). There were significantly more patients with National Institutes of Health Stroke Scale 0 or 1 at 90 days in the UK group than the control group (Pϭ0.017). The 90-day cumulative mortality was 5.3% in the UK group and 3.5% in the control group (Pϭ1.000), and intracerebral hemorrhage within 24 hours of treatment occurred in 9% and 2%, respectively (Pϭ0.206). Conclusions-The trial was aborted prematurely and the primary end point did not reach statistical significance.Nevertheless, the secondary analyses suggested that intraarterial fibrinolysis has the potential to increase the likelihood of excellent functional outcome.