Flow diversion: what can clinicians learn from animal models?

Introduction: Flow diversion is increasingly used for treating intracranial aneurysms. This article aims to review the evidence obtained from animal models and summarizes the findings that might be of clinical interest.

Methods: From a systematic review of studies published between 2000 and 2016, we extracted the data on the following questions: What roles do aneurysm dimension, morphology, and vascular geometry have on success of flow diversion? What characteristics of a flow diverter can influence aneurysm occlusion? What are the risk factors for jailed branch occlusion?

Results: Flow diversion has been shown to be less effective in occluding large aneurysms with wide or undefined necks, as compared to smaller aneurysms with narrower necks.

Flow diversion of bifurcation aneurysms is more effective when the jailed branch is occluded: an experimental study in a novel canine model.

Background: Flow diverters (FDs) are increasingly used for bifurcation aneurysms. Failure of aneurysm occlusion may be caused by residual flow maintaining patency of the jailed branch along with the aneurysm. Our aim was to test whether endovascular occlusion of the jailed branch could improve efficacy of flow diversion of bifurcation aneurysms.

Compaction of flow diverters improves occlusion of experimental wide-necked aneurysms.

Introduction: Flow diverters (FDs) are increasingly used in the treatment of wide-necked aneurysms.

Objective: To examine the hypothesis that intentional FD compaction might improve aneurysm occlusion rates.

Methods: Bilateral wide-necked carotid aneurysms were created in 12 dogs.

Uncertainty and agreement regarding the role of flow diversion in the management of difficult aneurysms.

Background And Purpose: The role of flow diversion in the management of aneurysms remains unknown. We sought to evaluate the community agreement regarding indications for flow diversion.

Materials And Methods: A portfolio of 35 difficult aneurysm cases was sent to 40 clinicians with varying backgrounds and experience.

Dual-lumen balloon catheters may improve liquid embolization of vascular malformations: an experimental study in Swine.

Background And Purpose: Liquid embolic agents are increasingly used to treat vascular malformations. We sought to assess embolization with these agents by using a dual-lumen balloon catheter in an experimental setting.

Materials And Methods: Eighteen injections of liquid embolic agents were performed in the rete mirabile of swine.

Interobserver agreement in the interpretation of outpatient head CT scans in an academic neuroradiology practice.

Background And Purpose: The repeatability of head CT interpretations may be studied in different contexts: in peer-review quality assurance interventions or in interobserver agreement studies. We assessed the agreement between double-blind reports of outpatient CT scans in a routine academic practice.

Materials And Methods: Outpatient head CT scans (119 patients) were randomly selected to be read twice in a blinded fashion by 8 neuroradiologists practicing in an academic institution during 1 year.

The success of flow diversion in large and giant sidewall aneurysms may depend on the size of the defect in the parent artery.

Background And Purpose: Flow diverters are designed to occlude aneurysms while preserving flow to jailed arterial branches. We postulated that treatment success depended on the size of the aneurysm ostium or defect in the parent artery.

Materials And Methods: Flow diverter expansion and deformation were studied in silicone tubes with wall apertures of various sizes.

Flow diversion of giant curved sidewall and bifurcation experimental aneurysms with very-low-porosity devices.

Objective: Flow diverters (FDs) are increasingly used to treat difficult intracranial aneurysms. The objective of this study was to test whether treatment challenges posed by giant curved sidewall (cSW) and endwall bifurcation (EwB) aneurysms can be overcome with the use of very-low-porosity devices.

Methods: Large and giant EwB (n = 12) and cSW aneurysms (n = 5) were constructed in 17 dogs.

In situ beta-irradiation of a brain arteriovenous malformation model.

Background And Purpose: The treatment of large brain arteriovenous malformations (BAVMs) is challenging, and embolization alone is seldom curative. The study goal is to enhance the efficacy of arteriovenous malformation embolization by adding a beta-emitting isotope to the embolic agent.

Methods: The pig rete mirabile was used as a BAVM model.

Anti-CD28 antibody- and IL-4-induced human T cell proliferation is sensitive to rapamycin.

Rapamycin (RAPA) is a potent immunosuppressant. In this study we investigated the effect of RAPA on T cell proliferation triggered by various stimuli in an in vitro human model. The proliferation of T cells stimulated via an alternative pathway using phorbol myristate acetate (PMA) and anti-CD28 antibody (alpha CD28) in the absence of antigen-presenting cells (APC) was strongly inhibited by RAPA.

Basal and inducible expression of metallothionein and heat shock protein 70 genes in bovine articular chondrocytes.

Human metallothionein (MT) and heat shock protein 70 (hsp70) cRNA probes cross-hybridized with the respective bovine mRNAs under high-stringency conditions, suggesting DNA sequence conservation of the two genes. Released primary bovine articular chondrocytes expressed MT and hsp70 mRNAs constitutively at variable levels, suggesting a possible physiological role of these proteins in cartilage. In first-passage chondrocytes both CdCl2 and ZnCl2 induced MT and hsp70 mRNAs.

Effects of nimesulide and naproxen on the degradation and metalloprotease synthesis of human osteoarthritic cartilage.

The aim of this study was to examine the effects of 2 nonsteroidal anti-inflammatory drugs (NSAIDs), nimesulide and naproxen, on the proteoglycan matrix breakdown and metalloprotease synthesis of human osteoarthritic cartilage. The results showed that, under in vitro conditions, these 2 NSAIDs could significantly reduce both the degradation of proteoglycan and stromelysin synthesis. However, only nimesulide had the ability to significantly reduce collagenase synthesis.

Expression of c-fos, c-jun, jun-B, metallothionein and metalloproteinase genes in human chondrocyte.

Normal and osteoarthritic (OA) human articular cartilage chondrocytes, released enzymatically in the presence of 0.5% fetal calf serum, display constitutive expression of early response activating protein (AP-1) genes; c-fos, c-jun and jun-B. Among the late AP-1 responsive genes, total metallothionein (MT) and stromelysin mRNAs were expressed at high levels in both normal and OA chondrocytes, while collagenase and hMT-IIA mRNA levels were elevated only in OA individuals.

Effects of tiaprofenic acid on plasminogen activators and inhibitors in human OA and RA synovium.

The effect of therapeutic and pharmacological concentrations of tiaprofenic acid, a non-steroidal anti-inflammatory drug (NSAID), on the synthesis of the plasminogen activators, urokinase plasminogen activator (uPA) and tissue plasminogen activator (tPA), and the plasminogen activator inhibitors 1 and 2 (PAI-1 and PAI-2), by human synovial membranes isolated from osteoarthritis (OA) and rheumatoid arthritis (RA) sufferers was evaluated. Both forms of plasminogen activator (PA) and PA inhibitor (PAI) were synthesized by the arthritic synovium. PAI-1 and PAI-2 were both synthesized in greater amounts than the plasminogen activators.

Antiproliferative effect of interleukin-4 in B chronic lymphocytic leukemia.

Recombinant interleukin-4 (IL-4) profoundly inhibits the proliferative response of chronic lymphocytic leukemic B cells (B-CLLs) to recombinant interleukin-2 (IL-2). In the present study, we confirmed and extended these data by showing that IL-4 strongly suppresses the [3H]thymidine incorporation by B-CLLs stimulated by recombinant tumor necrosis factor alpha, recombinant interferon alpha, IL-2, and low molecular weight B cell growth factor in the absence of costimulant. Recombinant interleukin-4 inhibits spontaneous DNA synthesis suggesting that it also interferes with the autocrine proliferation of these cells.

1,25(OH)2 vitamin D3 inhibits the CD23 gene expression by human peripheral blood monocytes.

A biologically active form of vitamin D, 1,25(OH)2D3, and a leukocyte surface molecule, CD23, play important roles in immune regulation. The effect of 1,25(OH)2D3 on the CD23 gene expression was examined in this study. The results show that 1,25(OH)2D3 suppresses spontaneous and IL-4-stimulated CD23 synthesis by peripheral blood monocytes.

IgE synthesis by chronic lymphocytic leukemia cells.

The present results indicate that B cells isolated from chronic lymphocytic leukemia (B-CLL) from 11 of 14 patients are capable of specifically producing IgE upon costimulation with IL-4 and hydrocortisone (HC). IgE is detected by intracytoplasmic fluorescence staining and by RIA. Clinical, hematological, and immunological parameters (including Rai stage, WBC, Lc, sIg kappa/lambda, CD5, and CD23 expression) cannot distinguish the IgE responder from the nonresponder patients.