We report an unusual case, which may provide insight into the etiology and pathogenesis of dural arteriovenous malformation.
A 24-year-old woman presented with hemorrhage into a pilocytic astrocytoma of the collicular plate. Angiography was normal and the tumor was surgically resected. She developed sigmoid sinus thrombosis and a transverse/sigmoid sinus dural arteriovenous fistula 11 months after this and was found to have protein S deficiency. The fistula was not treated. Angiography 4 years later was unchanged.
This report illustrates an acquired etiology of a dural arteriovenous fistula. To our knowledge this is the first reported case of postoperative sigmoid sinus thrombosis along with arteriovenous fistula in a patient with previously undetected protein S deficiency.
"Several studies have shown that dural AVF is associated with thrombosis of the involved sinus.9,10 One possible mechanism for the development of acquired dural AVF is that increased venous pressure after sinus thrombosis opens intrinsic channels between the cerebral arteries and venous sinuses.11 Another is that increased venous pressure may elicit local ischemia and increase ischemia-related angiogenesis.12 "
[Show abstract][Hide abstract] ABSTRACT: Carotid cavernous fistula (CCF) is an abnormal communication between the carotid artery and the cavernous sinus. The pathogenesis of spontaneous CCF remains unclear, although sinus thrombosis is known to be a predisposing factor for dural arteriovenous fistula. Because spontaneous CCFs are mainly of the dural type, we considered that thrombogenic conditions, such as, protein S deficiency might be associated with CCF.
A 42-year-old woman complained of conjunctival injection and retro-orbital pain that first appeared 1-month before visiting our hospital. She had no history of head trauma or intracranial surgery. Exophthalmos and chemosis were observed in her left eye, which also had lower visual acuity and higher intraocular pressure than the right eye. Magnetic resonance images and cerebral angiography revealed a left dural CCF. Her protein S was low, at 41% (normal range: 70-140%), but other hematologic values related to coagulation were normal. Her symptoms were relieved after initial transvenous coil embolization. However, a newly developed sixth-nerve palsy was detected 4 days after initial embolization. Follow-up angiography revealed a minimal shunt, and thus transvenous coil embolization was repeated. Two days later, the ophthalmoplegia started reducing, and 1-month later it had almost disappeared.
To the best of our knowledge, this is the first report of spontaneous dural CCF in a Korean patient with concurrent protein S deficiency. Interestingly, transient sixth-nerve palsy developed after transvenous coil embolization in this patient. This additional symptom caused by the residual fistula was relieved after additional transarterial embolization.
[Show abstract][Hide abstract] ABSTRACT: Our understanding of the pathogenesis of arteriovenous malformations (AVMs) and arteriovenous fistulas (AVFs) has been limited by the lack of adequate animal models. In this study we evaluate the time course of angiographic, hemodynamic and histopathological changes in an arteriovenous fistula in rats as a potential model.
An arteriovenous fistula was created by a side-to-end anastomosis of the common carotid artery (CCA) to the external jugular vein (EJV). The animals underwent angiography of the fistula and were sacrificed 1, 7, 21, 42 or 90 days later. Flow and pressure measurements were performed in the CCA and ipsi- and contralateral EJV and detailed histological examination of whole mount sections of the fistula and cranium were done on fixed sections. Immunohistochemistry for CD31, smooth muscle alpha-actin and Ki-67 were performed.
Hemodynamic changes occur immediately after fistula formation creating a stable high flow, low resistant state. This induces a gradual increase in the inner diameter of the EJV and transverse sinus followed by a decrease in size of the transverse sinus. This decrease is associated with increased expression of alpha-actin in the wall of the sinus. The fistula becomes angiographically and histologically stable after 21 days.
This model describes the time course of hemodynamic and histopathological changes after occur after AVF formation. Stabilization after 21 days makes it an attractive model for mechanistic and therapeutic studies of AVFs.
[Show abstract][Hide abstract] ABSTRACT: Genetic vaccinations, gene therapy, and manufacturing of therapeutic proteins would benefit from promoter sequences that provide improved or prolonged expression levels. The cytomegalovirus (CMV) promoter is one of the most potent promoters known to date, and no previous examples of improved activity of this promoter by sequence mutagenesis have been reported. This study describes directed molecular evolution of CMV promoters derived from two human and two nonhuman primate strains of CMV by DNA shuffling and screening. Libraries of chimeric promoters were screened and analyzed for expression levels and immune responses, using plasmid DNA vectors encoding luciferase and beta-galactosidase. The results indicate that high functional diversity among CMV promoters can be generated, and the chimeric promoters selected after two rounds of DNA shuffling and particularly designed screening assays provided approximately 2-fold increased luciferase reporter gene expression and anti-beta-galactoside antibody response in vivo when compared with wild-type promoters. Sequence analysis of the shuffled promoters identified several mutations potentially contributing to the observed enhanced or reduced promoter activities and identified a 42-nucleotide region that appears obsolete for the functioning of the CMV promoter. Taken together, these data demonstrate the feasibility of generating diverse promoter sequences by DNA shuffling and screening methods, and provide novel structure- function information about CMV promoters. DNA shuffling and screening technologies provide a new approach to promoter optimization and development of optimal expression vectors for genetic vaccinations, gene therapy, and protein expression.
Human Gene Therapy 08/2005; 16(7):881-92. DOI:10.1089/hum.2005.16.881 · 3.76 Impact Factor
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