Distribution of Cerebrovascular Phenotypes According to Variants of the ENG and ACVRL1 Genes in Subjects with Hereditary Hemorrhagic Telangiectasia

Hereditary Hemorrhagic Telangiectasia (HHT) is an autosomal dominant disorder caused, in more than 80% of cases, by mutations of either the endoglin (ENG) or the activin A receptor-like type 1 (ACVRL1) gene. Several hundred variants have been identified in these HHT-causing genes, including deletions, missense and nonsense mutations, splice defects, duplications, and insertions. In this study, we have analyzed retrospectively collected images of magnetic resonance angiographies (MRA) of the brain of HHT patients, followed at the HHT Center of our University Hospital, and looked for the distribution of cerebrovascular phenotypes according to specific gene variants. We found that cerebrovascular malformations were heterogeneous among HHT patients, with phenotypes that ranged from classical arteriovenous malformations (AVM) to intracranial aneurysms (IA), developmental venous anomalies (DVA), and cavernous angiomas (CA). There was also wide heterogeneity among the variants of the ENG and ACVRL1 genes, which included known pathogenic variants, variants of unknown significance, variants pending classification, and variants which had not been previously reported. The percentage of patients with cerebrovascular malformations was significantly higher among subjects with ENG variants than ACVRL1 variants (25.0% vs. 13.1%, p < 0.05). The prevalence of neurovascular anomalies was different among subjects with different gene variants, with an incidence that ranged from 3.3% among subjects with the c.1231C > T, c.200G > A, or c.1120C > T missense mutations of the ACVRL1 gene, to 75.0% among subjects with the c.1435C > T missense mutation of the ACVRL1 gene. Further studies and larger sample sizes are required to confirm these findings.

Surgical Treatment of Middle Cerebral Artery Aneurysms: Hints and Precautions for Young Cerebrovascular Surgeons

BACKGROUND AND OBJECTIVE

 Clipping is still considered the treatment of choice for middle cerebral artery (MCA) aneurysms due to their angioarchitectural characteristics as they are often bifurcation dysplasias, needing a complex reconstruction rather than a simple exclusion. Thus, maintaining this surgical expertise is of paramount importance to train of young cerebrovascular surgeons. To balance for the increasingly limited experience due the worldwide general inclination toward the endovascular approaches, it is important to provide to the young neurosurgeons rules and operative nuances to guide this complex surgery. We describe the technical algorithm we use to teach our residents to approach ruptured and unruptured MCA aneurysms, which may help to develop a procedural memory useful to perform an effective and safe surgery.

MATERIALS AND METHODS

 We reviewed our last 10 years' institutional experience of about 400 cases of ruptured and unruptured MCA aneurysms clipping, analyzing our technical refinements and the difficulties in residents and young neurosurgeons teaching, to establish fundamental key-points and design a didactic algorithm that includes operative instructions and safety rules.

RESULTS

 We recognized seven pragmatic technical key points regarding craniotomy, sylvian fissure opening, basal cisternostomy, proximal vessel control, lenticulostriate arteries preservation, aneurysm neck microdissection, and clipping to use as a didactic algorithm for teaching residents, and as operative instructions for inexperienced neurosurgeons.

CONCLUSION

 In the setting of clipping MCA aneurysms, respect for surgical rules is of paramount importance to perform an effective and safe procedure, ensure the best aneurysm exclusion, and preserve the flow in collaterals and perforators.

Sonic hedgehog is expressed in human brain arteriovenous malformations and induces arteriovenous malformations in vivo

Abnormalities in arterial versus venous endothelial cell identity and dysregulation of angiogenesis are deemed important in the pathophysiology of brain arteriovenous malformations (AVMs). The Sonic hedgehog (Shh) pathway is crucial for both angiogenesis and arterial versus venous differentiation of endothelial cells, through its dual role on the vascular endothelial growth factor/Notch signaling and the nuclear orphan receptor COUP-TFII. In this study, we show that Shh, Gli1 (the main transcription factor of the Shh pathway), and COUP-TFII (a target of the non-canonical Shh pathway) are aberrantly expressed in human brain AVMs. We also show that implantation of pellets containing Shh in the cornea of Efnb2/LacZ mice induces growth of distinct arteries and veins, interconnected by complex sets of arteriovenous shunts, without an interposed capillary bed, as seen in AVMs. We also demonstrate that injection in the rat brain of a plasmid containing the human Shh gene induces the growth of tangles of tortuous and dilated vessels, in part positive and in part negative for the arterial marker αSMA, with direct connections between αSMA-positive and -negative vessels. In summary, we show that the Shh pathway is active in human brain AVMs and that Shh-induced angiogenesis has characteristics reminiscent of those seen in AVMs in humans.

Combined Use of Color Doppler Ultrasound and Contrast-Enhanced Ultrasound in the Intraoperative Armamentarium for Arteriovenous Malformation Surgery

BACKGROUND

Safety and efficacy in surgical treatment of cerebral arteriovenous malformations (AVMs) are dictated by thorough understanding of angioarchitectural features, intraoperative identification of feeding vessels, and appreciation of surrounding eloquent areas. Our aim was to describe the preliminary results of combined application of color Doppler ultrasound (CDUS) and contrast-enhanced ultrasound (CEUS) in a consecutive surgical series of AVM. We pointed out the tool's efficacy in distinguishing feeding from bystander vessels and in identifying pattern of venous drainage. We examined its role as an adjunct for semiquantitative evaluation of the nidus inflow.

METHODS

We used combined CDUS and CEUS in patients surgically treated for cerebral AVMs. We adopted these techniques following a designed protocol to guide safer AVM resection as an adjunct to indocyanine green videoangiography. Intraoperative assessment by ultrasound was performed before, during, and following nidus resection.

RESULTS

Four surgically treated cerebral AVMs availed of the ultrasound protocol. Postoperative conventional angiography showed complete resection of the AVMs. CDUS and CEUS proved to be valuable adjunctive tools to indocyanine green videoangiography and micro-Doppler in properly navigating and discerning vascular structures, especially vessel feeders from bystanders. The protocol allows us to identify flow direction, estimate blood velocity within the nidus, and appreciate flow modifications following temporary clipping. Ultimately, it allows us to evaluate the degree of nidus deafferentation, residual flow, restoration of venous drainage and absence of arteriovenous shunts.

CONCLUSIONS

The CDUS and CEUS protocol is safe and repeatable and works as real-time imaging, further supporting complete surgical resection of AVMs.

Sortilin evokes endothelial dysfunction and arterial hypertension through the dysregulation of sphingolipid metabolism and oxidative stress

Background

Sortilin, a member of vacuolar protein sorting domain family Vps10, has been positively correlated with vascular and metabolic disorders in humans. Previous study has shown that, in response to Fas receptor stimulation, sortilin together with acid sphingomyelinase (ASMase) promote the clustering of lipid rafts and subsequent activation of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase in coronary endothelial cells. However, whether sortilin plays a role in endothelial cells function is currently unknown.

Purpose

To assess whether sortilin per se was able to influence vascular function, thereby contributing to the pathogenesis of cardiovascular diseases.

Methods

Pressure myography was used to study vascular reactivity of mesenteric arteries. To investigate the involvement of acid sphingomyelinase (ASM), we performed gene silencing approach and fluorometric activity assay. NADPH oxidase lucigenin assay was used to evaluate oxidative stress in endothelial cells and resistance vessels. The effects of circulating sortilin on cardiovascular system was evaluated by systemic delivery of recombinant sortilin protein to wild-type (WT), sphingosine-1-phosphate receptor 3 (S1P3) and NADPH oxidase 2 (gp91phox/NOX2) deficient mice. Systolic arterial blood pressure (SBP) was noninvasively registered in conscious mice by tail-cuff blood monitoring. Finally, to explore the translational relevance of sortilin, we measured sortilin and NOX2 soluble derived peptide levels using ELISA and quantified sphingosine-1-phosphate (S1P) by liquid chromatography–tandem mass spectrometry (LC-MS/MS) in plasma of hypertensive patients.

Results

Here we demonstrated that sortilin evoked endothelial dysfunction in mesenteric arteries due to increased NADPH oxidase-derived oxidative stress. Knockdown of ASM successfully prevented impairment of endothelial function. Using the inhibitor of sphingosine kinase type 1 (SphK1), sortilin failed to evoke endothelial impairment as well as NADPH oxidase activation. In endothelial cells, sortilin induced S1P-dependent activation of Rac1/NOX2 signaling axis, which was prevented by TY-52156, an antagonist of lysosphingolipid receptor S1P3. In vivo sortilin administration induced arterial hypertension in WT mice. In contrast, genetic deletion of S1P3 and gp91phox/NOX2 resulted in preservation of endothelial function and SBP unchanged levels after 14 days of systemic sortilin administration. Finally, to translate these research findings into a clinical setting, we found that hypertensive patients have higher plasma levels of sortilin, ASMase, S1P and soluble NOX2 derived peptide than normotensive subjects.

Conclusions

These results demonstrate the pathologic role of sortilin in the modulation of endothelial function and arterial blood pressure, suggesting that sortilin and its mediators might represent novel therapeutic targets in vascular diseases and hypertension.

Funding Acknowledgement

Type of funding source: None

Surgical Treatment of Anterior Communicating Artery Aneurysms: Hints and Precautions for Young Cerebrovascular Surgeons

Background Anterior communicating artery (AComA) aneurysms are the most common intracranial aneurysm, accounting for 25 to 38% of all cases. In spite of the advent of modern neurointerventional treatments, they still represent a strong indication for clipping in certain anatomical and clinical conditions. However, AComA aneurysms are the deepest located aneurysms of the anastomotic circle of Willis, with a complex spatial orientation, and they are fed by bilateral branches of the anterior circulations. Although, on one hand, these aneurysms represent the most complex ones of the anterior circulation, on the other hand, the experience of young neurosurgeons is increasingly limited. Therefore, respecting operative guidelines is crucial to achieve the best aneurysm exclusion and avoid fatal intraoperative complications.

Study Objective We describe the technical algorithm we use to teach young neurosurgeons how to approach AComA aneurysms and help them to develop a procedural memory needed to perform an efficient and safe surgery.

Materials and Methods We reviewed our last 10 years of institutional experience of > 200 cases of clipping ruptured and unruptured AComA aneurysms, analyzing our technical refinements and the difficulties in teaching residents and young neurosurgeons how to establish fundamental key points and design a didactic algorithm that includes operative instructions and safety rules.

Results We identified seven pragmatic technical key points regarding craniotomy, cisternostomy, gyrus rectus corticectomy, proximal control, perforators and Heubner preservation, aneurysm neck dissection, and clipping to use in a didactic algorithm for teaching residents and as operative instructions for inexperienced neurosurgeons.

Conclusion In the setting of clipping AComA aneurysms, respect for surgical rules is of paramount importance to perform an efficacious and safe procedure and ensure the best aneurysm exclusion and preservation of neurovascular structures.

Surgical Treatment of Posterior Communicating Artery Aneurysms: Hints and Precautions for Young Cerebrovascular Surgeons

Background In spite of the advent of neurointerventional treatment, different clinical and anatomical features are still strong indications for clipping of posterior communicating artery (PComA) aneurysms. But the experience of young neurosurgeons is increasingly limited, and therefore providing technical operative guidelines is a fundamental prerequisite to achieve the best aneurysm exclusion and avoid perioperative complications.

Study Objective We describe a technical algorithm we use to teach young neurosurgeons how to approach carotid aneurysms that may help them develop a procedural memory and thus perform an efficient and safe surgery.

Material and Methods We reviewed our last 10 years of institutional experience of > 150 cases of clipping ruptured and unruptured PComA aneurysms, analyzing our technical refinements and the difficulties in teaching residents and young neurosurgeons how to establish fundamental key points and design a didactic algorithm that includes operative instructions and safety rules.

Results We recognized seven pragmatic technical key points regarding craniotomy, cisternostomy, proximal and distal control, aneurysm neck dissection, preservation of neurovascular structures, and clipping to use in a didactic algorithm for teaching residents and as operative instructions for inexperienced neurosurgeons.

Conclusion In the setting of clipping PComA aneurysms, respect for surgical rules is of paramount importance to perform an efficacious and safe procedure and ensure the best aneurysm exclusion and preservation of neurovascular structures.

Antithrombotic therapy and intracranial bleeding in subjects with sporadic brain arteriovenous malformations: preliminary results from a retrospective study

Whether antithrombotic treatment is safe and/or affects the risk of intracranial bleeding in subjects with sporadic brain arteriovenous malformations (AVMs) is unknown. We conducted a retrospective analysis on the use of antithrombotics among patients affected by brain AVMs in follow-up at our institution. Attention was paid to the type of antithrombotic drug (either antiplatelets or anticoagulants), current or past use, dosage, and duration of treatment. Several clinical and angioarchitectural features of brain AVMs were also taken into consideration. The association between the use of antithrombotics and haemorrhagic onset was analyzed. A total of 77 patients were included in this study. Among them, ten patients were taking antithrombotic drugs at the time of AVM diagnosis. The rate of haemorrhagic onset was not significantly different between subjects who were and were not taking antithrombotic drugs (40 vs 55.2%, p = ns). Among the many clinical and angioarchitectural features analyzed, the only parameter that showed a statistically significant association with haemorrhagic onset was the size of the nidus. Patients who took antithrombotic treatments after being diagnosed with a brain AVM did not show an increased rate of intracranial haemorrhage over time considering a mean follow-up 4 years. In our study, antithrombotic treatment was not associated with increased intracranial bleeding among subjects with brain AVMs. In the presence of a strong clinical indication, antiplatelet and anticoagulant medications should not be denied a priori to patients with brain AVMs. Studies on larger populations are necessary to confirm these data.

Surgical Management of Intracranial Giant Epidermoid Cysts in Adult: A Case-Based Update

Epidermoid cysts (ECs) are benign and slow-growing lesions that account for about 0.2%-2% of all intracranial tumors. Symptoms appear slowly and tumors may have already grown to giant proportions when patients receive their first diagnosis. The optimal treatment for ECs is surgical removal, which includes the total resection of the entire capsule of the lesion in order to minimize the risk of malignant transformation associated with partial removal. However, considering the giant size that the ECs can reach at the time of the diagnosis, and their adherence to the surrounding structures, the risks and benefits of total versus subtotal resections in the short- and long-term patients' outcome are still under debate. Here, we report a case of an extensive giant EC and offer a discussion of its characteristics, surgical management, and postoperative outcome, taking a cue to argue about the recent literature based in the latest case studies.

Electrocardiographic-Guided Technique for Placement of Ventriculoatrial Shunts: A Valid and Cost-Effective Technical Simplification

BACKGROUND

Ventriculoatrial (VA) shunt is a routine technique for the treatment of hydrocephalus. The correct position at the superior vena cava-right atrium junction is generally assessed by radiography. We present the first experience of an alternative, nonradiographic technique to assess the distal end of the VA shunts through an electrocardiographic (EKG) method. The technique has developed from the large experience of central venous catheters (CVC) worldwide; the EKG-guided method is a common and validated alternative to standard radiologic control of the location of the tip of any CVC.

METHODS

Five consecutive patients underwent VA shunt with venous catheter positioned with the EKG-guided technique. The position of the catheter tip was verified by standard chest radiography.

RESULTS

Four men and 1 woman (mean age, 45.4 years) underwent VA shunt for hydrocephalus with the EKG-guided technique. The side of internal jugular vein puncture was the right side in 4 cases and the left side in 1 case. As confirmed by radiography, all VA shunt tips were located within the correct range. There was no radiologic evidence of procedure-related complication or catheters that had to be replaced.

CONCLUSIONS

The EKG-guided technique for VA shunts is as accurate as fluoroscopy, but simpler, more readily available, less expensive, safer, and more cost effective. It reduces the need of radiography and radiologic exposition for both patients and operators. The EKG method may be a valid and cost-effective alternative to standard radiologic control in VA shunts, as for any central venous access device, and could become the preferential method for confirming tip position during VA shunt surgery.

Angio-Architectural Features of High-Grade Intracranial Dural Arteriovenous Fistulas: Correlation With Aggressive Clinical Presentation and Hemorrhagic Risk

BACKGROUND: High-grade dural arteriovenous fistulas (dAVFs) can present shunts with very different angio-architectural characteristics. Specific hemodynamic factors may affect clinical history and determine very different clinical courses.

OBJECTIVES: To evaluate the relationship between some venous angio-architectural features in high-grade dAVFs and clinical presentation. Specific indicators of moderate or severe venous hypertension were analyzed, such as altered configurations of the dural sinuses (by a single or a dual thrombosis), or overload of cortical vessels (restrictions of outflow, pseudophlebitic cortical vessels, and venous aneurysms).

METHODS: The institutional series was retrospectively reviewed (49 cases), and the pattern of venous drainage was analyzed in relationship with clinical presentation (benign/aggressive/hemorrhage).

RESULTS: Thirty-five of 49 cases displayed cortical reflux (high-grade dAVFs). This subgroup displayed a benign presentation in 31.42% of cases, an aggressive in 31.42%, and hemorrhage in 37.14%.

CONCLUSIONS: Our data confirm that within high-grade dAVFs, 2 distinct subpopulations exist according to severity of clinical presentation. Some indicators we examined showed correlation with aggressive nonhemorrhagic manifestations (outflow restriction and pseudophlebitic cortical vessels), while other showed a correlation with hemorrhage (dual thrombosis and venous aneurysms). Current classifications appear insufficient to identify a wide range of conditions that ultimately determine the organization of the cortical venous drainage. Intermediate degrees of venous congestion correlate better with the clinical risk than the simple definition of cortical reflux. The angiographic aspects of venous drainage presented in this study may prove useful to assess dAVF hemodynamic characteristics and identify conditions at higher clinical risk.

Giant Basilar Artery Aneurysm Involving the Origin of Bilateral Posterior Cerebral and Superior Cerebellar Arteries: Neck Reconstruction with pCONus-Assisted Coiling

Giant aneurysms of the basilar artery are rare and are frequently associated with obstructive hydrocephalus and brainstem compression. Treatment still remains a challenge both for neurosurgeons and for interventional neuroradiologists. Cases reported in the literature are anecdotal and, overall, their outcomes are poor. We present the case of a patient with a giant aneurysm of the basilar artery tip, involving the origin of both the posterior cerebral and superior cerebellar arteries, who underwent coiling and ventriculoperitoneal shunting for associated obstructive hydrocephalus. A pCONus ® stent (Phenox; Bochum, Germany) was detached with its petals opened over the ostia of the parent vessels, with the aim being to reconstruct the neck of the aneurysm and to preserve the flow in the parent vessel. Moreover, the presence of the stent was useful to maintain the coils within the dome of the aneurysm. The pCONus is a new neurovascular device that is also useful for treating cases of complex basilar artery aneurysms when the ostia of the parent vessel origin is at the level of the aneurysm neck.

Minipterional Craniotomy for Treatment of Unruptured Middle Cerebral Artery Aneurysms. A Single-Center Comparative Analysis with Standard Pterional Approach as Regard to Safety and Efficacy of Aneurysm Clipping and the Advantages of Reconstruction

Pterional craniotomy (PT) has long been the standard approach for the treatment of middle cerebral artery (MCA) aneurysms, even though it may cause temporalis muscle atrophy, facial nerve injury, and masticatory difficulties. Minipterional craniotomy (MPT) is an alternative approach that may provide the same surgical corridor, limiting the risk of postoperative esthetic and functional complications. From January 2011 to December 2014 we consecutively performed 68 craniotomies for surgical treatment of unruptured MCA aneuryms: 37 were standard PT and 31 were MPT. There were no significant differences in mean age, sex, and aneurysm topography between the two groups. The mean skin incision length was 14 cm in the PT group and 6 cm in the MPT group. According to the Glasgow Outcome Scale (GOS) and modified Rankin Scale (mRS), there were no significant differences in clinical outcome at discharge or follow-up between the two groups. Also, the rates of complete aneurysm exclusion were comparable. However, the number of patients complaining of masticatory disorders was higher among those treated with PT. Finally, the number of complications observed in the PT group was higher than that in the MPT group, but only the differences in mean hospitalization length and necessity for a dural patch for reconstruction were statistically significant. In conclusion, the MPT approach is a safe and effective alternative to the standard PT for the treatment of unruptured MCA aneurysms.

Genome-wide association study of sporadic brain arteriovenous malformations

BACKGROUND

The pathogenesis of sporadic brain arteriovenous malformations (BAVMs) remains unknown, but studies suggest a genetic component. We estimated the heritability of sporadic BAVM and performed a genome-wide association study (GWAS) to investigate association of common single nucleotide polymorphisms (SNPs) with risk of sporadic BAVM in the international, multicentre Genetics of Arteriovenous Malformation (GEN-AVM) consortium.

METHODS

The Caucasian discovery cohort included 515 BAVM cases and 1191 controls genotyped using Affymetrix genome-wide SNP arrays. Genotype data were imputed to 1000 Genomes Project data, and well-imputed SNPs (>0.01 minor allele frequency) were analysed for association with BAVM. 57 top BAVM-associated SNPs (51 SNPs with p<10(-05) or p<10(-04) in candidate pathway genes, and 6 candidate BAVM SNPs) were tested in a replication cohort including 608 BAVM cases and 744 controls.

RESULTS

The estimated heritability of BAVM was 17.6% (SE 8.9%, age and sex-adjusted p=0.015). None of the SNPs were significantly associated with BAVM in the replication cohort after correction for multiple testing. 6 SNPs had a nominal p<0.1 in the replication cohort and map to introns in EGFEM1P, SP4 and CDKAL1 or near JAG1 and BNC2. Of the 6 candidate SNPs, 2 in ACVRL1 and MMP3 had a nominal p<0.05 in the replication cohort.

CONCLUSIONS

We performed the first GWAS of sporadic BAVM in the largest BAVM cohort assembled to date. No GWAS SNPs were replicated, suggesting that common SNPs do not contribute strongly to BAVM susceptibility. However, heritability estimates suggest a modest but significant genetic contribution.

Endovascular Treatment of the Posterior Cerebral Artery Aneurysms: Single-Center Experience and a Systematic Review

BACKGROUND

Endovascular treatment of posterior cerebral artery aneurysms is challenging because of the particular features of posterior circulation vessels. We performed a systematic review of the literature, to assess safety and efficacy associated to their endovascular treatment.

METHODS

Through a literature search, we identified 20 studies that met our inclusion criteria. We also performed a retrospective analysis of patients treated at our institution during the last 10 years. Demographics, angiographic features, clinical presentation, and outcome were extracted from each study. Data were combined using a random effects model and heterogeneity was assessed by I(2).

RESULTS

We retrieved 7 patients from our institutional series and 246 from the literature. Overall, 253/259 patients/aneurysms were included in this study. A selective coiling was performed in 27% of cases, a stent-assisted coiling in 2%, and a parent artery occlusion in 62%. Immediate complete/near-complete occlusion was obtained in 96% of cases and maintained in 90% at follow-up. No differences were observed between ruptured and unruptured aneurysms. Ischemic complications were reported in 15% of cases, although the most frequent was a hemianopsia in 7%; a hemiparesis was reported in only 2% of cases. Mortality was overall 1%. Ischemic complications were more frequent among patients who underwent nonselective treatment (P < 0.01).

CONCLUSIONS

Endovascular treatment of posterior cerebral artery aneurysms is associated with increased degree of occlusion and low recurrence rate. However, a parent artery occlusion implies complications, even although most of them are minor events such as hemianopsia.

Bilateral flow changes after extracranial-intracranial bypass surgery in a complex setting of multiple brain-feeding arteries occlusion: The role of perfusion studies

We report on a symptomatic case in which the whole intracranial blood supply was provided by a single vertebral artery as both internal carotid arteries were occluded and the contralateral vertebral artery was severely hypoplasic. The patient was treated by a flow-augmentation extracranial-intracranial bypass. Preoperative perfusion studies were essential in tailoring surgical strategy. Keypoints of the paper are contralateral perfusion changes after unilateral bypass surgery. The patient experienced a total recovery from symptoms and a bilateral improvement in brain perfusion, probably as consequence of post-operative hemodynamic rearrangement.

Association between polymorphisms rs1333040 and rs7865618 of chromosome 9p21 and sporadic brain arteriovenous malformations

BACKGROUND

The chromosomal locus 9p21 is a novel genetic marker for a variety of cardiovascular and cerebrovascular diseases. In a recent study, we have demonstrated an association between the single nucleotide polymorphism (SNP) rs1333040C>T on chromosome 9p21 and sporadic brain arteriovenous malformations (BAVMs). Here, we extended our analysis to an additional SNP on chromosome 9p21 (rs7865618A>G) and increased our sample size including BAVMs from two different Italian neurosurgical centers.

METHODS

We studied 206 patients with sporadic BAVMs and 171 unaffected controls. Genomic DNA was isolated from peripheral blood and the rs1333040C>T and rs7865618A>G polymorphisms were assessed by PCR-RFLP using the BsmI and MspI restriction endonucleases, respectively. For each SNP, we performed dominant, recessive, and additive genetic models.

RESULTS

The distribution of the three possible genotypes of rs1333040 (TT, TC and CC) was statistically different between cases and controls (p = 0.0008). The TT genotype was significantly associated with BAVMs both in the dominant (p = 0.013) and recessive (p = 0.012) models. The T allele was significantly associated with BAVMs in the additive model (p = 0.002). Also the distribution of the three possible genotypes of rs7865618 (GG, AG and AA) was statistically different between cases and controls (p = 0.005), and the GG genotype and G allele were significantly associated with BAVMs in the dominant (p = 0.032), recessive (p = 0.007), and additive models (p = 0.009). We also detected a significant association between BAVMs with large nidus size and the GG genotype and G allele of rs7865618 and the TT genotype of rs1333040. A deep venous drainage was instead associated with the TT genotype of the rs1333040 and the GG genotype of the rs7865618. The occurrence of bleeding was associated with the TT genotype and T allele of rs1333040, while the presence of seizures appeared associated with the GG genotype of rs7865618.

CONCLUSIONS

SNPs of the 9p21 region, in addition to be genetic markers for coronary artery disease, stroke, and intracranial aneurysms, are associated with sporadic BAVMs. These results extend and strengthen the role of the 9p21 chromosomal region as a common risk factor for cerebrovascular diseases.

Association between the rs1333040 polymorphism on the chromosomal 9p21 locus and sporadic brain arteriovenous malformations

BACKGROUND

Single nucleotide polymorphisms (SNPs) on chromosome 9p21 have been recently associated with intracranial aneurysms and stroke. In this study, we tested the association between the rs1333040C>T polymorphism on the 9p21 locus and sporadic brain arteriovenous malformations (BAVMs).

METHODS

We studied 78 patients with sporadic BAVMs and 103 unaffected controls. Genomic DNA was isolated from peripheral blood and the rs1333040C>T polymorphism was assessed by PCR-restriction fragment length polymorphism using the BsmI restriction endonuclease.

RESULTS

We found that the distribution of the three genotypes (TT/TC/CC) of the rs1333040 polymorphism was significantly different between cases and controls (p=0.02). Using dominant, recessive and additive genetic models, we found that the TT genotype and the T allele were significantly more common in the BAVM group than in controls. We also evaluated whether the rs1333040 polymorphism was associated with prototypical angio-architectural features of BAVMs (such as nidus size, venous drainage pattern and Spetzler-Martin grading) and with the occurrence of seizures and bleeding. We detected a significant association between the homozygous T allele in the recessive model and BAVMs with a nidus >4 cm in diameter. Deep venous drainage was significantly more frequent among subjects carrying at least one T allele in the dominant model. Patients with seizures showed a significant association with the TT genotype and the T allele in all genetic models examined whereas those who experienced intracranial bleeding showed a significant association with the T allele in the trend model.

CONCLUSIONS

This is the first study demonstrating an association between an SNP of the 9p21 region and sporadic BAVMs. Our results emphasise the relevance of this chromosomal locus as a common risk factor for various forms of cerebrovascular diseases.

In vivo laser assisted microvascular repair and end-to-end anastomosis by means of indocyanine green-infused chitosan patches: a pilot study

BACKGROUND AND OBJECTIVES

Laser-based repairing techniques offer several advantages respect to standard suturing in microsurgery. In this work we evaluate the applicability and feasibility of two innovative laser-based approaches for microvascular repair and anastomoses: (1) laser-assisted vascular repair (LAVR); (2) laser-assisted end-to-end vascular anastomosis (LAVA). All these procedures have been executed by the use of diode laser irradiation and chitosan-patches infused with Indocyanine Green (ICG).

STUDY DESIGN/MATERIALS AND METHODS

Experiments were performed on 30 rabbits. Twenty animals underwent LAVR and 10 end-to-end LAVA procedures. In the LAVR group, a 5-mm longitudinal cut was performed on the common carotid artery (CCA), then an ICG-infused chitosan patch was topically applied and laser-soldered over the arterial lesion. In the LAVA group the end-to-end anastomosis was executed on CCA by means of application of the three interrupted sutures and subsequent laser soldering of the ICG-infused patch. Animals underwent different follow-up periods (2, 7, 30, and 90 days). At the end of every follow-up, the animals were re-anesthetized and a microdoppler analysis was performed in order to check patency of the treated vessels. Then soldered segments were excised and subjected to histological and ultrastructural evaluations.

RESULTS

At the end of surgery no bleeding from the treated segment was observed; all the treated vessels were patent. At the end of follow-up periods, no signs of perivascular haemorrhage were found. An intraoperative microdoppler evaluation assessed the patency of all the treated vessels. Histology showed a good reorganization of the vascular wall structures and an early endothelial regeneration was observed by SEM.

CONCLUSIONS

Our study demonstrated the efficacy of laser tissue soldering by means of ICG-infused chitosan patches for the in vivo repairing of microvascular lesions and end-to-end anastomoses. This approach offers several advantages over conventional suturing methods and is technically easy to perform, minimizing the surgical trauma to vessels.

Relevance of bleeding pattern on clinical appearance and outcome in patients with hemorrhagic brain arteriovenous malformations

Although several descriptions of the angioarchitectural features of brain arteriovenous malformations (AVMs) associated with higher hemorrhagic risk have been reported, the prognostic value of the different bleeding patterns still needs to be elucidated. This study evaluated the influence on clinical appearance and outcome of the parenchymal and non-parenchymal (subarachnoid hemorrhage-SAH-and intraventricular hemorrhage-IVH) bleedings associated with ruptured AVMs. Clinical records and neuroradiological examinations of 30 patients with hemorrhagic AVMs were reviewed in order to identify their angioarchitectural features and the associated bleeding pattern. These data along with demographic characteristics and treatment modality were dichotomized and their relationship with clinical status at admission and follow-up was tested. IVH as well as parenchymal hematomas larger than 20 cm(3) appeared associated with a severe clinical status at admission, whereas SAH involving basal cisterns was significantly associated with unfavorable outcome. Age, sex and angioarchitectural features did not show significant association with the severity of the prognosis. However, none of these bleeding patterns appeared as an independent risk factor of poor outcome at multivariate analysis. In conclusion, our data emphasized the possibility that non-parenchymal bleeding may worsen the outcome of patients with hemorrhagic AVMs.

Nanotechnology and vascular neurosurgery: an in vivo experimental study on microvessels repair using laser photoactivation of a nanostructured hyaluronan solder

Sealing tissues by laser in neurosurgical procedures may overcome problems related to the use of conventional suturing methods which can be associated with various degrees of vascular wall damage. Despite the significant experimental and clinical achievements of the past, a standardized clinical application of laser-welding technology has not yet been implemented. The main problem is related to the use of common organic chromophores. A substantial breakthrough in the laser welding of biological tissues may come from the advent of nanotechnologies. In this paper we describe an experimental study, to confirm the feasibility of an innovative laser-assisted vascular repair (LAVR) technique based on diode laser irradiation and subsequent photoactivation of a hyaluronan solder embedded with near infrared (NIR) absorbing gold nanorods (GNRs), and to analyze the induced closuring effect in a follow-up study performed in animal model. Twenty New Zealand rabbits underwent closure of a 3-mm longitudinal incision performed on the common carotid artery (CCA) by means of 810 nm diode laser irradiation, in conjunction with the topical application of an optimized GNR composite. Effective closure of the arterial wound was accomplished by using very low laser intensity (30 W/cm2). The average CCA occlusion time was as low as 50 sec. Animals underwent different follow-up periods (2, 8, 30 days). After follow-up, they were re-anesthetized, the patency of the treated vessels was tested (Doppler analysis) and then the irradiated vessels were excised and subjected to histological evaluations. Morphological examinations of the samples documented the integrity of the vascular wall. No host reaction to nanoparticles occurred. Collagen and elastic fibers returned to their normal architecture 30 days after treatment. A Scanning Electron Microscopy (SEM) examination and immuno-histochemical analysis demonstrated a full re-endothelization of the vessel walls. We thus confirmed that a laser-based approach is technically easy to perform, and provides several advantages, such as a simplification of the surgical procedure, a reduction in the operative time, and the suppression of bleeding. The use of GNRs improves the selectivity of welding and minimizes the surgical trauma to vessels, resulting in an optimal healing process.

Present status and new perspectives in laser welding of vascular tissues

The laser welding of biological tissues is a particular use of lasers in surgery. The technique has been proposed since the 1970s for surgical applications, such as repairing blood vessels, nerves, tendons, bronchial fistulae, skin and ocular tissues. In vascular surgery, two procedures have been tested and optimized in animal models, both ex vivo and in vivo, in order to design different approaches for blood vessels anastomoses and for the repair of vascular lesions: the laser-assisted vascular anastomosis (LAVA) and the laser-assisted vessel repair (LAVR). Sealing tissues by laser may overcome the problems related to the use of conventional closuring methods that are generally associated with various degrees of vascular wall damage that can ultimately predispose to vessel thrombosis and occlusion. In fact, the use of a laser welding technique provides several advantages such as simplification of the surgical procedure, reduction of the operative time, suppression of bleeding, and may guarantee an optimal healing process of vascular structures, very similar to restitutio ad integrum. Despite the numerous preclinical studies performed by several research groups, the clinical applications of laser-assisted anastomosis or vessel repair are still far off. Substantial breakthrough in the laser welding of biological tissues may come from the advent of nanotechnologies. Herein we describe the present status and the future perspectives in laser welding of vascular structures.

Intraparenchymal recurrence of a dural meningioma: association with rhabdoid alterations with aggressive biological and clinical behaviour

A 47-year-old man underwent surgery for syncytial meningioma. Twelve months later neuroimaging demonstrated recurrence, showing an intra-axial ring-enhanced cystic lesion in the site of previous surgery. High-grade glioma was suspected. Neuropathologist's diagnosis was 'intraparenchymal rhabdoid meningioma'. The case raises questions about behaviour of meningiomas and their differential diagnosis with gliomas.

Pathological enlargement of midbrain Virchow-Robin spaces: a rare cause of obstructive hydrocephalus

Midbrain multiloculated cystic formations can rarely origin by enlargement of Virchow-Robin spaces surrounding mesencephalo-thalamic artery and branches of the collicular and accessory collicular arteries. They can determine several pictures of midbrain syndrome and obstructive hydrocephalus. The authors describe a 38 year-old man affected by a Benedikt's syndrome related to a midbrain multicystic formation. Clinical course, differential diagnosis, and therapeutic choice are here also briefly discussed.

In vivo carotid artery closure by laser activation of hyaluronan-embedded gold nanorods

We prove the first application of near-infrared-absorbing gold nanorods (GNRs) for in vivo laser closure of a rabbit carotid artery. GNRs are first functionalized with a biopolymeric shell and then embedded in hyaluronan, which gives a stabilized and handy laser-activable formulation. Four rabbits undergo closure of a 3-mm longitudinal incision performed on the carotid artery by means of a 810-nm diode laser in conjunction with the topical application of the GNRs composite. An effective surgery is obtained by using a 40-W/cm(2) laser power density. The histological and electron microscopy evaluation after a 30-day follow-up demonstrates complete healing of the treated arteries with full re-endothelization at the site of GNRs application. The absence of microgranuloma formation and/or dystrophic calcification is evidence that no host reaction to nanoparticles interspersed through the vascular tissue occurred. The observation of a reshaping and associated blue shift of the NIR absorption band of GNRs after laser treatment supports the occurrence of a self-terminating process, and thus of additional safety of the minimally invasive laser procedure. This study underlines the feasibility of using GNRs for in vivo laser soldering applications, which represents a step forward toward the introduction of nanotechnology-based therapies in minimally invasive clinical practices.

An experimental study on minimally occlusive laser-assisted vascular anastomosis in bypass surgery: the importance of temperature monitoring during laser welding procedures

Laser welding has been proposed as an alternative technique to conventional stitching in microvascular anastomosis, with the advantages of improving the vascular healing process and reducing the risk of malfunction of a bypass. Our group recently proposed a laser-assisted end-to-side anastomotic technique, providing the advantages of laser welding and reducing the occlusion time of the recipient vessel, that is important in neurosurgical bypass procedures, in order to reduce the risk of cerebral ischemia. This in vivo study focuses on the control of the temperature dynamics developing in the welded tissue. A jugular vein graft was harvested and implanted on the rabbit carotid artery by means of two end-to-side anastomosis. Laser welding procedure was then carried out to implant the bypass. A real-time monitoring of the temperature during welding was performed with an infrared thermocamera, in order to control the laser-induced heating effect on the external surface of the vessel walls. The temperature analysis highlighted the dynamic of the heating effect in space and time and enabled us to define an optimal temperature range in operative conditions. The temperature control provided safe tissue heating confined within the directly irradiated area, with negligible damage to surrounding tissues, as well as effective sealing and welding of the vessel edges at the anastomotic sites. The average occlusion time of the carotid artery was about 11 minutes. After a follow-up of 30 days, all the bypasses were patent and no signs of thrombosis or leak point pressure were present, thus confirming the safety of this laser-assisted anastomotic procedure.

Occipital ganglio-neuroblastoma in an adult

INTRODUCTION

Ganglioneuroblastomas (GNBs) are embryonic neoplasms, whose behaviour are not well established; 80% of cases occur in the first decade, while only two cases in the adulthood had been reported.

CLINICAL REPORT

This 60-year-old female presented with a 2-month history of headache, vertigo, amnesia. A right brachio-crural hemiparesis, right homonymous hemianopsia and sensorial dysphasia was evident. A CT scan revealed a left occipital lesion. MRI scan was not performed because the patient had an anal sphincter stimulator. Three years before thyroidectomy for a follicular carcinoma was performed. A total body CT scan was negative. A left occipital craniotomy was carried out and a solid mass was totally excised. A diagnosis of GNB was made from histopathological examination and immunohistochemistry. Post-operatively the patient recovered from the hemiparesis while the visual disturbances persisted. She underwent fractioned radiotherapy (60 Gy) and chemotherapy with Temozolomide. She remained disease free 18 months after diagnosis. A CT scan showed no evidence of recurrence.

DISCUSSION

Recent observations suggest that in spite of an embryonal appearance, these tumours are circumscribed and have a better prognosis than malignant gliomas.

Minimally occlusive laser vascular anastomosis (MOLVA): experimental study

BACKGROUND

Temporary occlusion of an intracranial artery during microvascular anastomosis is a major risk factor in cerebrovascular surgery. A new laser vascular welding technique that minimizes the occlusion time of the recipient vessel has been developed and is described in this report.

METHOD

A new minimally occlusive technique of end-to-side microvascular anastomosis was developed employing a diode laser in association with the application of a chromophore in our experimental model of double end-to-side anastomosis. The implantation of a vein graft on the patent carotid artery was obtained through the application of three interrupted sutures at each anastomotic site; the carotid was then clamped, two arteriotomies were performed, followed by the application of a fourth suture and of the laser welding procedure on each anastomosis. Monitoring of the temperature at the site of the anastomosis was introduced in order to control the welding technique.

FINDINGS

The time of the clamping of the carotid artery was 12 min to perform two end-to-side anastomoses (i.e., 6 min for each anastomosis). All bypasses were patent after a follow-up of 90 days and histological study confirmed good preservation of the vascular wall.

CONCLUSIONS

Our laser-assisted technique of vascular anastomosis reduces the duration of the clamping of the recipient artery down to 6 min. This technique can minimize the risk of cerebral ischemia associated with occlusion of a recipient artery in intracranial bypass procedures, promoting an improved vascular healing process with a lower risk of thrombosis and occlusion.

Diode laser-assisted carotid bypass surgery: an experimental study with morphological and immunohistochemical evaluations

OBJECTIVE

Conventional suturing methods of microvascular anastomosis are associated with various degrees of vascular wall damage that can lead to thrombosis and bypass occlusion. An experimental model of double end-to-side venous graft anastomosis on the common carotid artery was set up to compare conventional suturing methods with a low-power diode laser vascular welding technique.

METHODS

The experiments were performed on 40 rabbits that underwent implantation of a 15-mm segment of jugular vein on the common carotid artery. The proximal end-to-side suture was performed by eight interrupted stitches; the distal suture, which was done using a laser welding technique, was supported by four stay sutures. The animals were evaluated after 2 days (n = 15), 9 days (n = 15), and 30 days (n = 10). The vascular segments were excised and subjected to histological, immunohistochemical, and ultrastructural evaluation.

RESULTS

The average clamping time to perform both anastomoses was 35 minutes. At the end of the follow-up period, one case of complete occlusion was observed after 9 days and one case was observed after 30 days. Surgical observations and pathological evaluation indicated that adoption of the laser welding technique reduced operative time and bleeding. Histologically, a reduction of thrombosis, inflammation, myointimal hyperplasia, and dystrophic calcification was observed in laser-assisted anastomoses. A better preservation of the endothelium was also evident in laser-treated anastomoses. The observed differences were deemed statistically significant (P < 0.05).

CONCLUSION

Our study demonstrated the efficacy of diode laser welding in improving surgical techniques of high-flow bypass and in reducing the vascular wall damage observed with conventional methods.

Middle cerebral artery dolichoectasia in a young woman with a previous stroke

We observed a 32-year-old female who had suffered from a left hemisphere ischemic stroke with right hemiparesis at the age of seven. At that time, a CT scan demonstrated a left ischemic lesion in nucleo-capsular region and a cerebral angiogram documented a complete occlusion of the supraclinoid segment of the internal carotid artery. When we observed the patient neurological examination demonstrated a moderate right brachio-crural hemiparesis. A brain MRI showed an old ischemic lesion involving the left nucleo-capsular and 'flow voids' suggestive for a vascular malformation in the left sylvian region. A cerebral rotational angiogram with 3-D reconstructions demonstrated a dolichoectatic left middle cerebral artery with an unusual 'corkscrew' aspect. Middle cerebral artery dolichoectasia is a rare pathological condition that may manifest with a stroke. The patients with intracranial arterial dolichoectasia (IADE) are most often hypertensive elderly men, and, to the best of our knowledge, an ischemic stroke associated with IADE has never been reported in children.

Intracranial meningiomas associated with non-traumatic chronic subdural hematoma

BACKGROUND

Non-traumatic subdural hematomas are very rarely associated with intracranial meningiomas. Pathophysiological mechanisms of such an association are not yet fully understood.

CASE DESCRIPTION

We report on two patients harboring an intracranial meningioma and ipsilateral non-traumatic chronic subdural hematoma. Their history was negative for risk factors for subdural hematoma. Both patients were submitted to surgery for evacuation of the subdural collection. The presence of the meningioma was discovered during surgery. A second operation was necessary in our first case.

CONCLUSIONS

We retrospectively analyzed our radiological data and the literature to provide some features that may help in the pre-operative diagnosis of a meningioma in patients presenting with a chronic subdural hematoma. Furthermore the mechanisms responsible for this association are discussed on the basis of our pathological evidence.

Ganglioglioma arising in a Peutz-Jeghers patient: a case report with molecular implications

The Peutz-Jeghers syndrome (PJS), an autosomal dominant disorder caused by inactivating germline mutations in the serine-threonine kinase gene LKB1, is characterized by mucocutaneous pigmentation, multiple gastrointestinal hamartomatous polyps, and by an increased risk for developing tumors involving several different organs. To date, no brain tumors have been described in PJS patients. In this report, we describe a case of ganglioglioma in a 22-year-old PJS patient. Single-strand conformation polymorphism-Heteroduplex analysis evidenced an abnormal pattern in exon 6 of the LKB1 gene. Sequencing revealed a 821delTinsAC mutation creating a termination codon 29 nucleotides downstream (p.Asn274fsX11). RNA studies showed an out-of-frame LKB1 isoform derived from the wild type allele and generated by exon 4 skipping. Since the LKB1 gene is expressed in the fetal and adult brain, our data would suggest its likely involvement in the pathogenesis of a subset of gangliogliomas.

Cavernous hemangioma extending to extracranial, intracranial, and orbital regions

✓ Extraaxial cavernous hemangiomas are rare intracranial lesions that can be located in different cranial compartments. Extension across different tissue planes such as the subcutaneous tissue, skull, orbital cavity, intracranial dura mater, and extracranial trigeminal divisions within the same patient has not been previously reported.

This 32-year-old woman suffered left exophthalmos, left sixth nerve palsy, and trigeminal neuropathy. Magnetic resonance imaging studies revealed an extensive multicompartmental lesion, with enhancement following Gd administration.

A left orbitopterional approach allowed removal of several cavernomatous lesions located in the orbit, frontotemporal dura, and lateral wall of the cavernous sinus. A histologically based diagnosis of extraaxial cavernous hemangioma was made. In the postoperative period the patient experienced a regression of her symptoms.

The authors report on a case of cavernous hemangioma with a unique extension to different intracranial/extracranial compartments. Although radical removal of the lesion was not feasible, partial excision allowed for satisfactory clinical control of the patient's symptoms.

Effects of thyroid state on H2O2 production by rat heart mitochondria: sites of production with complex I- and complex II-linked substrates

This work was designed to determine possible effects of altered thyroid states on rates and sites of H 2 O 2 production by rat heart mitochondria. Rates of O 2 consumption and H 2 O 2 release, capacities to remove the peroxide, lipid peroxidation, cytochrome oxidase activities and ubiquinone levels were determined in heart mitochondria from euthyroid, hypothyroid, and hyperthyroid rats. Hypothyroidism decreased, whereas hyperthyroidism increased the rates of O 2 consumption and H 2 O 2 release during both state 4 and state 3 respiration with Complex I- or Complex II-linked substrates. The percentage of O 2 released as H 2 O 2 was not significantly affected by thyroid state. However, the mitochondrial capacity to remove H 2 O 2 increased in the transition from hypothyroid to hyperthyroid state, which indicates that H 2 O 2 production did not modify in proportion to the rate of O 2 consumption. The thyroid-state-linked changes in H 2 O 2 production were well correlated with the levels of hydroperoxides. Rates of H 2 O 2 release in the presence of respiratory inhibitors indicated that changes in the H 2 O 2 production occurred at both sites at which H 2 O 2 was generated in euthyroid state. This result and the observation that ubiquinol levels and cytochrome oxidase activities increase in the transition from hypothyroid to hyperthyroid state suggest that the modifications of H 2 O 2 production are due to a modulation by thyroid hormone of mitochondrial content of autoxidisable electron carriers.

Multifocal cerebral hemangio-endothelioma. Case report and review of the literature

BACKGROUND

Intracranial hemangio-endotheliomas (HE) are rare vascular tumours that present histological features and biological behaviour of an intermediate malignancy. We report the first case of primary HE presenting as multiple intracranial masses.

CASE DESCRIPTION

The patient is a 20-year-old female who presented with paresis of the left arm. Magnetic Resonance imaging (MRI) showed multiple lesions in both frontal lobes. Total surgical excision of the tumours was obtained; a histological diagnosis of hemangio-endothelioma was made. Five months later, MRI scan showed new intradiploic skull lesions whereas a scintigraphic study revealed multicentric extracranial bone involvement. Treatment based on interferon-alpha (IFN-alpha) administration was undertaken; this produced partial regression of the lesions. Approximately three years after the first operation, the patient is in good clinical condition.

CONCLUSIONS

Surgery continues to play the leading role in the treatment of intracranial HE. However, adjuvant therapy with IFN represents a new and well-tolerated therapeutic method for residual intracranial lesions as well as multicentric extracranial disease.

Occipital condylar fractures: a review

The purpose of this review article is to summarize the epidemiology, pertinent anatomy, mechanisms of injury, and classification systems of occipital condylar fractures (OCFs), as well as their clinical presentation and screening, the importance of computed tomography (CT) for detection, and current treatment options. The authors emphasize the rate of occurrence of OCFs, which may be detected in as many as 16% of patients with craniocervical injury. Clinical presentation is not specific, and OCF is not readily diagnosed at physical examination. Failure to diagnose may result in substantial morbidity, and thus accurate diagnosis is mandatory for both therapeutic and medicolegal implications. The diagnosis is most likely to be made with CT. Thin-section CT technique is the method of choice to evaluate the traumatized craniocervical junction. OCFs should be suspected in all patients sustaining high-energy blunt trauma to the head and/or upper cervical spine, resulting from axial loading, lateral bending and/or rotation, and/or direct blow. Besides a CT study assessing potential intracranial injuries, these patients require CT of the craniocervical junction. Radiologists should be aware of the types of OCFs and associated injuries.

Craniovertebral junction malformation and rotational occlusion of the vertebral artery

An unusual case of rotational occlusion of a non-dominant vertebral artery (VA) is presented. This clinical syndrome is associated for the first time with a complex craniovertebral junction malformation. Rotational occlusion of the VA is usually asymptomatic, vertebro-basilar insufficiency has been rarely observed in cases of involvement of a dominant VA, and concomitant occlusion or hypoplasia of the contralateral artery. Diagnosis of rotational VA occlusion is based on haemodynamic demonstration of the effects of head rotation. The importance of the awareness of this syndrome is stressed.

Characterization of caveolae from rat heart: localization of postreceptor signal transduction molecules and their rearrangement after norepinephrine stimulation

Caveolae are plasma membrane subcompartments that have been implicated in signal transduction. In many cellular systems, caveolae are rich in signal transduction molecules such as G proteins and receptor-associated tyrosine kinases. An important structural component of the caveolae is caveolin. Recent evidence show that among the caveolin gene family, caveolin-3 is expressed in skeletal and cardiac muscle and caveolae are present in cardiac myocyte cells. Both the ANP receptor as well as the muscarinic receptor have been localized to the caveolae of cardiac myocytes in culture. These findings prompted us to conduct a further analysis of cardiac caveolae. In order to improve our understanding of the mechanisms of signal transduction regulation in cardiac myocytes, we isolated cardiac caveolae by discontinuous sucrose density gradient centrifugation from rat ventricles and rat neonatal cardiocytes. Our analysis of caveolar content demonstrates that heterotrimeric G proteins, p21ras and receptor-associated tyrosine kinases are concentrated within these structures. We also show that adrenergic stimulation induces an increase in the amount of diverse alpha- and beta-subunits of G proteins, as well as p21ras, in both in vivo and in vitro experimental settings. Our data show that cardiac caveolae are an important site of signal transduction regulation. This finding suggests a potential role for these structures in physiological and pathological states.