Early Hemodynamic Response Assessment of Stereotactic Radiosurgery for a Cerebral Arteriovenous Malformation Using 4D Flow MRI.

Brain AVMs treated with stereotactic radiosurgery typically demonstrate a minimum latency period of 1-3 years between treatment and nidus obliteration. Assessment of treatment response is usually limited to evaluation of AVM nidus structural changes using conventional MR imaging and MRA techniques. This report describes the use of 4D Flow MRI to also measure radiation-induced hemodynamic changes in a Spetzler-Martin grade III AVM, which were detectable as early as 6 months after treatment.

Neuroimaging findings of the post-treatment effects of radiation and chemotherapy of malignant primary glial neoplasms.

Post-treatment radiation and chemotherapy of malignant primary glial neoplasms present a wide spectrum of tumor appearances and treatment-related entities. Radiologic findings of these post-treatment effects overlap, making it difficult to distinguish treatment response and failure. The purposes of this article are to illustrate and contrast the imaging appearances of recurrent tumor from necrosis and to discuss other radiologic effects of cancer treatments. It is critical for radiologists to recognize these treatment-related effects to help direct clinical management.

Inhibitory specificity of the anti-inflammatory myxoma virus serpin, SERP-1.

SERP-1 is a myxoma virus-encoded serpin, secreted from infected cells, that is required for virulence and has anti-inflammatory activity. We report that purified recombinant SERP-1 forms SDS-stable complexes with urokinase-type plasminogen activator (uPA), tissue-type plasminogen activator (tPA), plasmin, thrombin, and factor Xa. N-terminal sequencing confirmed Arg319-Asn320 as the site of reaction. Mutation of these residues to Ala-Ala abolished inhibitory activity but had no effect on the specific cleavage at Thr315-Leu316 seen with elastase and with cathepsin G. Kinetic analysis of the reactions with uPA, tPA, plasmin, thrombin, Xa, and C1s showed second-order rate constants to vary over 3 logs, from kinh = 3 x 10(5) M-1 s-1 with thrombin to approximately 600 M-1 s-1 with C1s, while steady-state inhibition constants ranged from KI = 10 pM with thrombin to approximately 100 nM with C1s. Stoichiometries of inhibition varied between SI = 1.4 +/- 0.1 for uPA to SI = 13 +/- 3 for thrombin. Analysis of the variations in inhibition kinetics shows that when serpins act at low concentrations, comparable with the target protease or with KI (as appears likely for SERP-1 in vivo), inhibitory specificity becomes less dominated by kinh and is increasingly dependent on partitioning within the branched reaction mechanism and on the lifetime of the inhibited complex.