A nonadhesive liquid embolic agent of ethylene vinyl alcohol copolymer and ethanol mixture for cerebral arteriovenous malformations. Clinical experience

SUMMARY

We report our experience using our new nonadhesive liquid embolic agent, an ethylene vinyl alcohol copolymer (EVAL)/Ethanol mixture, to treat human arteriovenous malformations (AVM). Between June 1995 and April 2001, 57 patients with confirmed AVM underwent embolization with the EVAL/Ethanol mixture. Using 87 procedures consisting of one to three stages, we embolized 185 feeding arteries to occlude as much of the AVM as possible. Repeated injections under fluoroscopic control could be performed smoothly without encountering cementing of the catheter in the vessel wall. Among 87 procedures undertaken in 57 patients, seven (8.0%) procedures in six patients produced new postembolization symptoms. Resolution of these symptoms occurred within hours or days following four of the seven procedures; permanent neurological deficits remained after three embolization procedures (3.4%). Of the 57 patients, three underwent postembolization radiosurgery, 54 were radically treated with microsurgical extirpation. Histopathological examinations of the 54 specimens disclosed mild inflammation within the embolized lumen without inflammatory reactions in the media or adventitia. Follow-up angiograms obtained three years after they underwent radiosurgery showed that in all three patients the nidus had completely disappeared. The EVAL/Ethanol mixture is handled easily and appears to be an effective and safe embolic agent for the preoperative embolization of AVM.

Correction of a genetic defect in multipotent germline stem cells using a human artificial chromosome

Human artificial chromosomes (HACs) have several advantages as gene therapy vectors, including stable episomal maintenance that avoids insertional mutations and the ability to carry large gene inserts including regulatory elements. Multipotent germline stem (mGS) cells have a great potential for gene therapy because they can be generated from an individual's testes, and when reintroduced can contribute to the specialized function of any tissue. As a proof of concept, we herein report the functional restoration of a genetic deficiency in mouse p53-/- mGS cells, using a HAC with a genomic human p53 gene introduced via microcell-mediated chromosome transfer. The p53 phenotypes of gene regulation and radiation sensitivity were complemented by introducing the p53-HAC and the cells differentiated into several different tissue types in vivo and in vitro. Therefore, the combination of using mGS cells with HACs provides a new tool for gene and cell therapies. The next step is to demonstrate functional restoration using animal models for future gene therapy.

Differentiation between paraclinoid and cavernous sinus aneurysms with contrast-enhanced 3D constructive interference in steady- state MR imaging

BACKGROUND AND PURPOSE

Differentiation between paraclinoid and cavernous sinus aneurysms of the internal carotid artery (ICA) is critical when considering treatment options. The purpose of this study was to determine whether contrast-enhanced (CE) 3D constructive interference in steady state (CISS) MR imaging is useful to differentiate between paraclinoid and cavernous sinus aneurysms.

MATERIALS AND METHODS

This study included 11 aneurysms in 10 consecutive female patients, ranging from 52 to 66 years of age. All aneurysms were adjacent to the anterior clinoid process. After conventional and CE 3D-CISS imaging on a 1.5T MR imaging unit, all patients underwent surgery, and the relationship between the aneurysms and the dura was confirmed. Two neuroradiologists evaluated the location of the aneurysms on CE 3D-CISS images and classified them as intradural, partially intradural, and extradural aneurysms. Operative findings were used as a reference standard. To understand the imaging characteristics, we assessed the boundary and signal intensity of the cavernous sinus, CSF, and carotid artery on the side contralateral to the lesion.

RESULTS

Operative findings disclosed that 5 aneurysms were intradural and 6 were extradural. All except 2 were accurately assessed with CE 3D-CISS imaging. One intradural aneurysm adjacent to a large cavernous aneurysm and 1 cavernous giant aneurysm were assessed as partially intradural. On CE 3D-CISS images, the boundary between the CSF, cavernous sinus, and carotid artery was identified by high signal-intensity contrast in all cases.

CONCLUSION

CE 3D-CISS MR imaging is useful for the differentiation between paraclinoid and cavernous sinus aneurysms.

A small-molecule compound targeting CCR5 and CXCR3 prevents airway hyperresponsiveness and inflammation

Asthma is associated with increased numbers of T-cells in the lung. CC chemokine receptor (CCR)5 and CXC chemokine receptor (CXCR)3 have been reported to play important roles in the lung T-cell homing pathway, and may be potential targets for asthma therapy. The aim of the present study was to investigate the role of CCR5 and CXCR3 in allergen-induced acute asthma and to determine whether a novel small-molecule compound, TAK-779, targeting CCR5 and CXCR3 can attenuate allergic airway responses. Mice were sensitised with ovalbumin (OVA). mRNA expression of chemokine receptors in the lung were measured after the challenge with either aerosolised phosphate-buffered saline or OVA. OVA-sensitised mice were also treated with TAK-779. Respiratory function was measured, bronchoalveolar lavage was performed, and blood and lung samples were obtained. OVA challenge increased CCR3, CCR5 and CXCR3 expression in the lung. Treatment with TAK-779 significantly attenuated altered respiratory function and pulmonary allergic inflammation. The beneficial effect was associated with reduced expression of CCR5 and CXCR3 in the lung. These data demonstrate that blockade of CC chemokine receptor 5 and CXC chemokine receptor 3 using TAK-779, a synthetic nonpeptide compound, can prevent the development of asthma features in a mouse model. Thus, CC chemokine receptor 5 and CXC chemokine receptor 3 may be potential targets for asthma therapy.

Up-regulation of proteinase-activated receptor 1 and increased contractile responses to thrombin after subarachnoid haemorrhage

BACKGROUND AND PURPOSE

The mechanism for the development of post-haemorrhagic cerebral vasospasm after subarachnoid haemorrhage (SAH) still remains unknown.

EXPERIMENTAL APPROACH

We investigated the role of thrombin and its receptor PAR1 in the development of hyper-contractility of the basilar artery in a rabbit double haemorrhage model, which received two injections of autologous blood into the cisterna magna.

KEY RESULTS

In the basilar artery isolated from the control rabbits, thrombin, only at 10 units ml(-1), induced a transient endothelium-dependent relaxation and a slight smooth muscle contraction. In SAH, the contractile response to thrombin was markedly enhanced, while the endothelium-dependent relaxant effect of thrombin remained unchanged. The enhancement of the contractile responses was also observed in the absence of endothelium and thrombin induced an enhanced contraction at concentrations higher than 0.3 units ml(-1). The contractile response to PAR1-activating peptide was also enhanced after SAH. However, the contractile responses to high K+ and endothelin-1, and the myofilament Ca2+-sensitivity remained unchanged after SAH. An immunoblot analysis suggested the up-regulation of PAR1 in the smooth muscle of the basilar artery. The heparinization of blood before injection prevented the enhancement of the contractile responses to thrombin and PAR1-activating peptide.

CONCLUSIONS AND IMPLICATIONS

The present study demonstrated, for the first time, that the contractile response of the basilar artery to thrombin was markedly enhanced after SAH. Mechanistically, our findings suggested that the activation of thrombin following hemorrhage up-regulated the expression of PAR1, thereby inducing the hyper-responsiveness to thrombin.

Multiple peripheral middle cerebral artery aneurysms associated with Behcet's disease

We report a 19-year-old woman with Behcet's disease who suffered a subarachnoid hemorrhage and had bilateral peripheral middle cerebral artery aneurysms. After steroid therapy for 3 days, the smaller aneurysm disappeared. The larger aneurysm was excised and the artery reconstructed using a superficial temporary artery graft. Histological examination showed vasculitis restricted to the wall of the aneurysm. This is the first report of arterial reconstruction for an aneurysm associated with Behcet's disease. Steroid therapy before the operation may facilitate repair of the arterial wall.

External Manual Carotid Compression is Effective in Patients with Cavernous Sinus Dural Arteriovenous Fistulae

SUMMARY

External manual carotid compression is a non-invasive method to treat patients with cavernous sinus dural arteriovenous fistulae (CSDAVF). We studied a group of patients with CSDAVF to identify factors that made cure by compression therapy possible. We treated 23 patients with CS-DAVF without cortical venous drainage or a recent decline in visual acuity by compression therapy. All were followed up by magnetic resonance angiography (MRA) at one, three, six, and 12 months after treatment and the characteristics of the imaging findings, their neurological symptoms, and the patterns of symptom improvement were examined. In group A (n=8), cure was achieved by manual carotid compression; in the other 15 patients (group B), cure was not obtained. Group B manifested significantly higher ocular pressure and a significantly longer interval between symptom onset and treatment by manual carotid compression. In group A, venous drainage was via the superior orbital vein (SOV) with/without involvement of the inferior petrosal sinus (IPS); closure of the CS-DAVF occurred within 4.1 months after the start of treatment. In three patients symptom improvement progressed steadily and gradually. The other five cured patients experienced transient worsening of their symptoms at two to four months after the start of treatment, these resolved within four to seven months. Manual carotid compression was effective in patients without retrograde venous CS-DAVF drainage or a severe decline in visual acuity. The factors that rendered cure by compression therapy possible were lower ocular pressure and a shorter interval between symptom onset and the start of treatment. Venous drainage in those patients was exclusively via the SOV without involvement of the IPS.

Therapeutic effect of a new immunosuppressive agent, everolimus, on interleukin-10 gene-deficient mice with colitis

A limited number of therapeutic strategies are currently available for patients with inflammatory bowel disease (IBD). In particular, the maintenance therapy after remission in Crohn's disease (CD) is not satisfactory and new approaches are needed. Interleukin-10 gene-deficient (IL-10-/-) mice, a well-characterized experimental model of CD, develop severe chronic colitis due to an aberrant Th1 immune response. Everolimus, an inhibitor of the mammalian target of rapamycin (mTOR), a new immunosuppressive reagent, has been used successfully in animal models for heart, liver, lung and kidney transplantation. In the present study, we examined the efficacy of everolimus in the treatment of chronic colitis in an IL-10-/- mouse model. Everolimus was administered orally for a period of 4 weeks to IL-10-/- mice with clinical signs of colitis. The gross and histological appearances of the colon and the numbers, phenotype and cytokine production of lymphocytes were compared with these characteristics in a control group. The 4-week administration of everolimus resulted in a significant decrease in the severity of colitis, together with a significant reduction in the number of CD4+ T cells in the colonic lamina propria as well as IFN-gamma production in colonic lymphocytes. Everolimus treatment of established colitis in IL-10-/- mice ameliorated the colitis, probably as a result of decreasing the number of CD4+ T cells in the colonic mucosa and an associated reduction in IFN-gamma production.

Pharmacological activity and structural analysis of a benzamide (TKS159) and its optical isomers in an in vitro study and in an in vivo study in mice

We previously conducted an in vitro study of 4-amino-5-chloro-2-methoxy-N-(1-ethyl-2-hydroxymethyl-4-pyrrolidinyl)benzamide (2S,4S)-(1, TKS159) and its three optical isomers (2S,4R)-(2), (2R,4S)-(3) and (2R,4R)-(4) with respect to their binding ability to the 5-HT(4) receptors, as well as an in vivo study on their gastric emptying-accelerating ability in rats. Consequently, we reported that steric configuration at positions 2 and 4 of the pyrrolidine ring is important in determining their pharmacological activity. The optical isomer (2R,4S)-(3) exhibited the most potent binding ability. However, the compound (2S,4S)-(1, TKS159) exhibited the most potent gastric emptying-accelerating ability in rats. A difference was thus found between binding ability and gastric emptying-accelerating ability in rats. Therefore, we conducted an in vitro study of TKS159 (1) and its three optical isomers to examine their agonistic activity on the 5-HT(4) receptors, as well as an in vivo study in mice to examine their gastric emptying-accelerating ability. Consequently, a tendency for correlation was found between the activity and the ability. TKS159 (1) exhibited the most potent pharmacological activity, well reflecting the results from the previous in vivo study in rats. Furthermore, the present in vitro and in vivo studies reverified the importance of steric configuration at positions 2 and 4 of the pyrrolidine ring. In addition, we also made an X-ray crystallographic analysis of the optical isomer (2R,4S)-(3), which has the S-configuration at position 4 similar to TKS159 (1), and discussed molecular structures in conjunction with the previously reported results from the X-ray crystallographic analysis of TKS159 (1).

Clinical evaluation of cellulose porous beads for the therapeutic embolization of meningiomas

BACKGROUND AND PURPOSE

Cellulose porous beads (CPBs) are a new, exceptionally uniformly sized, nonabsorbable embolic agent. We evaluated their efficacy in the preoperative embolization of meningiomas.

METHODS

In 141 consecutive patients, we used CPBs (200-microm diameter) for the preoperative embolization of meningiomas. We selected patients whose tumors were > or =4 cm with 50% of blood to the tumor supplied by the external carotid artery (ECA). All patients underwent a provocation test before embolization. The percentage of blood supplied to the tumor by the internal carotid artery and ECA was determined angiographically. Nonenhanced areas on postembolization MR imaging were calculated. Intraoperative blood loss, units of blood transfusion, and hemostasis at the time of surgery were recorded for each patient. The interval between embolization and surgery was intentionally longer than 7 days.

RESULTS

Of the 141 patients, 128 underwent CBP embolization. Eleven patients had positive provocation test results, and 2 had vasospasm; they were not CBP embolized. In 72% of the patients CBP embolization achieved reduction in the flow of the feeding artery by more than 50%. The nonenhanced area on MR imaging was not significantly correlated with the degree of ECA supply or devascularization. The interval between embolization and surgery was 8-26 days (mean, 9.9 days). The longer this interval, the greater was the tumor-softening effect and the rate of tumor removal.

CONCLUSIONS

CPBs may be useful for the preoperative embolization of meningiomas. To increase the efficacy of CPB embolization, the interval to surgery should be at least 7 days.

Engineering of Escherichia colil-serine O-acetyltransferase on the basis of crystal structure: desensitization to feedback inhibition by l-cysteine

L-Serine O-acetyltransferase (SAT) from Escherichia coli catalyzes the first step of L-cysteine synthesis in E.coli and is strictly inhibited by the second step product, L-cysteine. To establish a fermentation process to produce L-cysteine, we embarked on a mutational study of E.coli SAT to desensitize the feedback inhibition by L-cysteine. The crystal structure and the reaction mechanism of SAT from E.coli have shown that the substrate L-serine and the inhibitor L-cysteine bind to the identical region in the SAT protein. To decrease the affinity for only L-cysteine, we first built the structure model of L-serine-binding SAT on the basis of the crystal structure with bound L-cysteine and compared these two structures. The comparison showed that the Calpha of Asp92 underwent a substantial positional change upon the replacement of L-cysteine by L-serine. We then introduced various amino acid substitutions at positions 89-96 around Asp92 by randomized, fragment-directed mutagenesis to change the position of the Asp92. As a result, we successfully obtained mutant SATs which have both extreme insensitivity to an inhibition by L-cysteine (the concentration that inhibits 50% activity; IC(50) = 1,100 micromol/l, the inhibition constant; K(i) = 950.0 micromol/l) and extremely high emzymatic activities.

Evaluation of the Stability of Small Ruptured Aneurysms with a Small Neck after Embolization with Guglielmi Detachable Coils. Correlation between Coil Packing Ratio and Coil Compaction

SUMMARY

It is difficult to predict the compaction of Guglielmi detachable coils (GDC) after endovascular surgery for aneurysms. Therefore, we studied the relationship between the coil packing ratio and compaction in 62 patients with acute ruptured intracranial aneurysms that were small (< 10 mm) had a small neck (< 4 mm) and were coil-embolized with GDC-10. We recorded the maximum prospective coil length, L, as the length that correspond with the volume of packed coils occupying 30% of the aneurysmal volume. L was calculated as L (cm) = 0.3 x a x b x c and the coil packing ratio expressed as packed coil length/L x 100, where a, b, and c are the aneurysmal height, length, and width in mm, respectively. Angiographic followup studies were performed at three months and one and two years after endovascular surgery. Of the 62 patients, 16 (25.8%) manifested angiographic coil compaction (ten minor and six major compactions); the mean coil packing ratio was 51.9 +/- 13.4%. The mean coil packing ratio in the other 46 patients was 80.5 +/- 20.2% and the difference was statistically significant (p < 0.01). In all six patients with major compaction the mean packing ratio was below 50%. We detected 93.8% of the compactions within 24 months of coil placement. In patients with small, necked aneurysms, the optimal coil packing ratio could be identified with the formula 0.3 x a x b x c. The probability of compaction was significantly higher when the coil packing ratio was under 50%. To detect coil compaction post-embolization, follow-up angiograms must be examined regularly for at least 24 months.