Internal Carotid Artery Injection Research Articles

Repurposing mebendazole against triple-negative breast cancer CNS metastasis.

Triple-negative breast cancer (TNBC) often metastasizes to the central nervous system (CNS) and has the highest propensity among breast cancer subtypes to develop leptomeningeal disease (LMD). LMD is a spread of cancer into leptomeningeal space that speeds up the disease progression and severely aggravates the prognosis. LMD has limited treatment options. We sought to test whether the common anti-helminthic drug mebendazole (MBZ) may be effective against murine TNBC LMD. A small-molecule screen involving TNBC cell lines identified benzimidazoles as potential therapeutic agents for further study. In vitro migration assays were used to evaluate cell migration capacity and the effect of MBZ. For in vivo testing, CNS metastasis was introduced into BALB/c athymic nude mice through internal carotid artery injections of brain-tropic MDA-MB-231-BR or MCF7-BR cells. Tumor growth and spread was monitored by bioluminescence imaging and immunohistochemistry. MBZ was given orally at 50 and 100mg/kg doses. MBZ bioavailability was assayed by mass spectrometry. Bioinformatic analysis and migration assays revealed higher migratory capacity of TNBC compared to other breast cancer subtypes. MBZ effectively slowed down migration of TNBC cell line MDA-MB-231 and its brain tropic derivative MDA-MB-231-BR. In animal studies, MBZ reduced leptomeningeal spread, and extended survival in brain metastasis model produced by MDA-MB-231-BR cells. MBZ did not have an effect in the non-migratory MCF7-BR model. We demonstrated that MBZ is a safe and effective oral agent in an animal model of TNBC CNS metastasis. Our findings are concordant with previous efforts involving MBZ and CNS pathology and support the drug's potential utility to slow down leptomeningeal spread.

Abstract Number ‐ 80: Embolization of Carotid Cavernous Fistula Through Occluded Inferior Petrosal Sinus Access

Introduction Carotid cavernous fistula (CCF) is an abnormal communication between arteries and veins within the cavernous sinus. The most common presenting symptoms are proptosis, chemosis, orbital bruit and headache. Visual disturbances such as diplopia, ophthalmoplegia and cranial nerve deficits can also occur. Pulsatile tinnitus is an unusual finding which necessitates further workup in this population. Endovascular obliteration with transvenous embolization for indirect fistulas is the preferred approach for CCF closure. Navigation is achieved through the inferior petrosal sinus or facial and superior ophthalmic vein. Here, we describe a case of carotid cavernous fistula that was successfully treated through occluded right inferior petrosal sinus access using coil and Onyx embolic material. Methods A 56‐year‐old‐male with no past medical history presented with right eye proptosis and pulsatile tinnitus. His eye symptoms progressively worsened with decrease in visual acuity, gaze restriction and exophthalmos which correlated with the resolution of pulsatile tinnitus. MRI demonstrated significant inflammation involving the right orbit and atypical enhancement of basal frontal lobe adjacent to orbit. MRA suggested early opacification of the right superior ophthalmic vein and subtle flow voids in posterior lateral aspect of right cavernous sinus. Further evaluation with cerebral angiogram revealed a Barrow Type D right carotid cavernous fistula supplied by meningo‐hypophyseal branches of bilateral internal carotid arteries and right internal maxillary branch. It demonstrated high flow retrograde shunting in right superior ophthalmic vein and a basal frontal isolated cortical vein. There was near complete occlusion of the right sigmoid sinus and inferior petrosal sinus due to significant thrombus burden as well as stenosis of the right internal jugular vein. Results Patient underwent embolization of right carotid cavernous fistula with transvenous approach. A microcatheter was advanced to the origin of the intercavernous sinus but was not able to cross due to exceptionally small channels connecting both cavernous sinuses. The right internal jugular vein was subsequently identified and injection demonstrated occlusion of right sigmoid sinus due to near complete occlusive thrombus in addition to occlusion of the major channels of the inferior petrosal sinus. The microcatheter was blindly advanced into the inferior petrosal sinus maintaining the symmetry from contralateral inferior petrosal sinus trajectory. We were able to reach the fistulous point in the posterior medial aspect of the right cavernous sinus using an Echelon 1045 microcatheter. Coils were subsequently deployed and fistula was noted to be occluded. Onyx was injected through the microcatheter to avoid recanalization of fistula. A follow‐up left internal carotid artery and right common carotid artery injections confirmed angiographic cure of the fistula. Conclusions Carotid cavernous fistula is a rare but treatable cause of rapidly progressive vision loss with pulsatile tinnitus as an unusual finding. We present a case of challenging access and successful treatment with transvenous approach through near complete occlusion of the inferior petrosal sinus.

Modeling Brain Metastasis by Internal Carotid Artery Injection of Cancer Cells.

Brain metastasis is a cause of severe morbidity and mortality in cancer patients. Critical aspects of metastatic diseases, such as the complex neural microenvironment and stromal cell interaction, cannot be entirely replicated with in vitro assays; thus, animal models are critical for investigating and understanding the effects of therapeutic intervention. However, most brain tumor xenografting methods do not produce brain metastases consistently in terms of the time frame and tumor burden. Brain metastasis models generated by intracardiac injection of cancer cells can result in unintended extracranial tumor burden and lead to non-brain metastatic morbidity and mortality. Although intracranial injection of cancer cells can limit extracranial tumor formation, it has several caveats, such as the injected cells frequently form a singular tumor mass at the injection site, high leptomeningeal involvement, and damage to brain vasculature during needle penetration. This protocol describes a mouse model of brain metastasis generated by internal carotid artery injection. This method produces intracranial tumors consistently without the involvement of other organs, enabling the evaluation of therapeutic agents for brain metastasis.

頭蓋底骨折後遅発性に鼻出血を契機に発見された内頸動脈仮性瘤の1例(A case of delayed discovery of a internal carotid artery pseudoaneurysm by nosebleeds after skull base fracture)

要旨 頭部外傷に伴う頭蓋底骨折はときに仮性動脈瘤を合併する。今回我々は，頭蓋底骨折後受傷時に損傷を認めなかった右内頸動脈に遅発性に仮性動脈瘤を形成した1例を経験したので報告する。症例は74歳の男性。約3mの高さから墜落し顔面を強打した。救急隊接触時，外表上頭部・顔面に外傷を認め，発語不能であったため，重症頭部外傷が疑われ当院へ搬送された。来院時CT検査において右視神経損傷を伴う頭蓋底骨折，脳挫傷，外傷性くも膜下出血，右肩甲骨骨折，多発肋骨骨折を認めたが，仮性動脈瘤は認めなかった。上記各外傷に対し保存的加療を行い，第19病日軽快転医となった。第38病日初回の鼻出血を認めた。第47病日中等量の鼻出血を認め，鼻腔内ガーゼ充填で止血を得た。第79病日より隔日で鼻出血を認めるようになったが，耳鼻科診察では鼻粘膜に特記すべき異常を認めなかった。第84病日多量の鼻出血と血圧低下，冷汗を認め，造影CTで右内頸動脈に仮性動脈瘤を認めたため，当院へ再度転医となった。第85病日右浅側頭動脈–中大脳動脈吻合術および右内頸動脈瘤コイル塞栓術を行い，第90病日MRAで瘤への血流がないことを確認した。第96病日に転医し，第106病日独歩退院となった。本症例では頭部外傷後の鼻出血により，仮性動脈瘤を発見し得た。頭蓋底骨折後の血管評価は受傷時に損傷を認めなくても継時的な画像評価などを慎重に行う必要がある。

Is a trident or a bident? Appearance of a primitive trigeminal artery on sagittal views

•Recognition of a persistent primitive trigeminal artery (PPTA) is of clinical significance due to its association with aneurysms and several vascular variants in addition to preoperative planning.•Characteristic appearance of PPTA on MR sagittal images of the brain resembles the Greek letter tau (two prongs) and was linked to Neptune’s trident (three prongs).•Use of a bident sign as a more visually and mythologically precise description of the appearance of PPTA. A 50 year old male with an incidental finding on the MRI brain (Fig. 1).Fig. 2A) Lateral digitally subtracted catheter angiogram of a selected internal carotid artery (arrow) injection demonstrating the persistent trigeminal artery (arrowhead) passing posteriorly to join the basilar artery (open arrow). B) Cropped view of the painting “Concilio degli dei” by Raffaello Sanzio da Urbino depicting Hades holding a bident (left), next to his brother Poseidon holding a trident (middle) [10]. Zeus (right) is also pictured, without a spear.View Large Image Figure ViewerDownload Hi-res image Download (PPT) A.fetal posterior cerebral arteryB.persistent trigeminal arteryC.persistent hypoglossal arteryD.persistent otic arteryE.persistent proatlantal artery Answer on page 240 Is a trident or a bident? Appearance of a primitive trigeminal artery on sagittal viewsJournal of Clinical NeuroscienceVol. 75PreviewA persistent primitive trigeminal artery (PPTA) is the remnant of the embryonic arterial circulation in adults and is the most common type of the persistent carotid-vertebrobasilar anastomoses (with frequency 0.1–0.6%); followed by persistent hypoglossal artery (0.02–0.1%), persistent proatlantal artery and otic artery, which existence, however, remains controversial [6,7]. A PPTA arises from the proximal cavernous part of the ICA and courses posteriorly to join the basilar artery. Recognition of a PPTA is of clinical significance due to its association with aneurysms and several vascular variants [1,4]. Full-Text PDF Erratum to “Is a trident or a bident? Appearance of a primitive trigeminal artery on sagittal views – Question and Is a trident or a bident? Appearance of a primitive trigeminal artery on sagittal views – Answer” [J. Clin. Neurosci. 75C (2020) 204–205 and 240–241]Journal of Clinical NeuroscienceVol. 78PreviewThe publisher regrets to inform readers that there was an error in the article title for both the question and answer articles. The correct title is ‘Is it a trident or a bident? Appearance of a persistent primitive trigeminal artery on sagittal views – Question’ and ‘Is it a trident or a bident? Appearance of a persistent primitive trigeminal artery on sagittal views – Answer’ respectively. Full-Text PDF

Safety of Intraventricular rt-PA for Pan-Ventricular IVH Caused by a Ruptured AVM: A Case Report.

Intraventricular recombinant tissue plasminogen activator (IVT rt-PA) has improved outcomes for intraventricular hemorrhage (IVH). Patients with suspected or untreated arteriovenous malformations (AVMs) have been excluded from clinical trials. We present a patient with IVH secondary to a ruptured AVM safely treated with IVT rt-PA. A 48-year-old Hispanic male with a history of dermatomyositis presented to the emergency department with sudden left-sided weakness. En route to computed tomography (CT), he became lethargic. Computed tomography revealed extensive IVH with acute hydrocephalus, which was treated with the placement of external ventricular drain with clinical improvement. Computed tomography angiogram performed did not reveal AVM. Cerebral digital subtraction angiogram (DSA) was planned due to suspicion of AVM. Prior to DSA, patient became acutely lethargic. Computed tomography imaging revealed worsening hydrocephalus. External ventricular drain was noted to be draining. Repeat CT revealed improved hydrocephalus but with left lateral ventricle dilatation. Risks and benefits of IVT rt-PA were discussed with the family and a decision was made to treat. Three doses of 1 mg IVT rt-PA were administered with resolution of midline blood and lateral ventricular dilatation with clinical improvement. Digital subtraction angiogram revealed early draining vein on right internal carotid artery injection draining into the inferior sagittal sinus representing ruptured AVM without clear nidus. Repeat DSA with possible embolization was planned after discharge. In spite of additional in-hospital complications, the patient gradually improved and was ultimately discharged home. Our case supports the idea that the use of IVT rt-PA following an IVH caused by an underlying AVM could be further explored in carefully designed clinical trials.

An unusual cause of massive hemoptysis

A 65-year old woman presented with recurrent hemoptysis. Four years earlier she had been treated (surgery plus radio-chemotherapy) for a cervical esophageal cancer with regional lymph nodes metastasis. Endoscopies showed areas of recent bleeding in the right pharynx. A 3D reconstruction from a CT angiogram of the neck vessels demonstrated a right internal carotid artery (ICA) pseudo-aneurysm. Selective endovascular occlusion of the aneurysm was planned. However, the patient had a recurrence of severe haemoptysis during coiling. A selective right ICA injection showed an extravascular jet of contrast medium filling the pharynx. Occlusion of the ICA and the pseudo-aneurysm (trapping) was performed as quickly as possible successfully staunching the bleed. Selective left ICA injection confirmed occlusion of the right ICA and satisfactory cross filling through the anterior communicating artery. The woman was discharged and the hemoptysis never recurred.

Initial clinical experience with near-infrared spectroscopy in assessing cerebral tissue oxygen saturation in cerebral vasospasm before and after intra-arterial verapamil injection

Cerebral vasospasm is a devastating complication after subarachnoid hemorrhage. The use of cerebral tissue oxygen saturation (SctO2) to non-invasively assess changes in cerebral tissue perfusion induced by intra-arterial (IA) verapamil treatment has not been described to our knowledge. A total of 21 consecutive post-craniotomy patients scheduled for possible IA verapamil treatment of cerebral vasospasm were recruited. The effect of IA verapamil injection on SctO2 being continuously monitored on both the left and right forehead was investigated. Comparisons between changes in SctO2 monitored on the ipsilateral and contralateral forehead in relationship to the side of internal carotid artery (ICA) injection were performed. A total of 47 IA verapamil injections (15 left ICA, 18 right ICA, and 14 vertebral artery injections) during 18 neurointerventional procedures in 13 patients were analyzed. IA verapamil administration led to both increases and decreases in SctO2. Changes in SctO2 ipsilateral to the ICA injection side were more pronounced (p=0.02 and 0.07 for left and right ICA injections, respectively) and favored compared to contralateral SctO2 changes. We were unable to obtain reliable measurements on the side ipsilateral to the craniotomy during four procedures in three patients, presumably secondary to pneumocephalus. The local cerebral vasodilating effect of IA verapamil injection is suggested by the differential changes in SctO2 ipsilateral and contralateral to the ICA injection side. The inconsistent changes in SctO2 and the limitations of applying cerebral oximetry in this patient population needs to be recognized.

Chronic intermittent hypoxia increases sympathetic control of blood pressure: role of neuronal activity in the hypothalamic paraventricular nucleus

Like humans with sleep apnea, rats exposed to chronic intermittent hypoxia (CIH) experience arterial hypoxemias and develop hypertension characterized by exaggerated sympathetic nerve activity (SNA). To gain insights into the poorly understood mechanisms that initiate sleep apnea/CIH-associated hypertension, experiments were performed in rats exposed to CIH for only 7 days. Compared with sham-treated normoxic control rats, CIH-exposed rats (n = 8 rats/group) had significantly increased hematocrit (P < 0.001) and mean arterial pressure (MAP; P < 0.05). Blockade of ganglionic transmission caused a significantly (P < 0.05) greater reduction of MAP in rats exposed to CIH than control rats (n = 8 rats/group), indicating a greater contribution of SNA in the support of MAP even at this early stage of CIH hypertension. Chemical inhibition of neuronal discharge in the hypothalamic paraventricular nucleus (PVN) (100 pmol muscimol) had no effect on renal SNA but reduced lumbar SNA (P < 0.005) and MAP (P < 0.05) more in CIH-exposed rats (n = 8) than control rats (n = 7), indicating that CIH increased the contribution of PVN neuronal activity in the support of lumbar SNA and MAP. Because CIH activates brain regions controlling body fluid homeostasis, the effects of internal carotid artery injection of hypertonic saline were tested and determined to increase lumbar SNA more (P < 0.05) in CIH-exposed rats than in control rats (n = 9 rats/group). We conclude that neurogenic mechanisms are activated early in the development of CIH hypertension such that elevated MAP relies on increased sympathetic tonus and ongoing PVN neuronal activity. The increased sensitivity of Na(+)/osmosensitive circuitry in CIH-exposed rats suggests that early neuroadaptive responses among body fluid regulatory neurons could contribute to the initiation of CIH hypertension.

A novel method for efficient delivery of stem cells to the ischemic brain

IntroductionRat middle cerebral artery occlusion (MCAO) model is the most commonly used animal model in ischemic stroke studies. In the model, to increase the amount of stem cells or drugs to enter the brain after delivery into the internal carotid artery (ICA), the pterygopalatine artery (PPA) is occluded. However, PPA occlusion is a technically demanding procedure which often causes complications.MethodsIn this study, we developed an ICA injection needle to facilitate easy and efficient delivery of stem cells to the ischemic brain through the ICA without the need of PPA occlusion. We injected methylene blue and fluorescence dye DiI-labeled human mesenchymal stem cells (DiI-hMSCs) into the ICA in rats with the ICA injection needle (without PPA ligation) or the conventional micro-injection needle (with PPA ligation) and assessed their distributions.ResultsWhen methylene blue was injected, evident blue stains were found in the brain of the injection side particularly the middle cerebral artery (MCA)-supplied areas but not in the PPA supplied areas. Similarly, when DiI-hMSCs were injected, the cells largely appeared in the MCA-supplied tissues, which were similar in quantity compared to conventional micro-injection needle injection with PPA occlusion. Moreover, hMSCs injected with the ICA needle or the micro-injection needle similarly improved the functional recovery of the infarcted brain.ConclusionsOur results indicate that the ICA injection needle is easy to use and efficient in delivering cells to the ischemic brain tissue in rat MCAO model.

Characterisation of Walker 256 breast carcinoma cells from two tumour cell banks as assessed using two models of secondary brain tumours

BackgroundMetastatic brain tumours are a common end stage of breast cancer progression, with significant associated morbidity and high mortality. Walker 256 is a rat breast carcinoma cell line syngeneic to Wistar rats and commonly used to induce secondary brain tumours. Previously there has been the assumption that the same cancer cell line from different cell banks behave in a similar manner, although recent studies have suggested that cell lines may change their characteristics over time in vitro.MethodsIn this study internal carotid artery injection and direct cerebral inoculation models of secondary brain tumours were used to determine the tumorigenicity of Walker 256 cells obtained from two cell banks, the American Type Culture Collection (ATCC), and the Cell Resource Centre for Medical Research at Tohoku University (CRCTU).ResultsTumour incidence and volume, plus immunoreactivity to albumin, IBA1 and GFAP, were used as indicators of tumorigenicity and tumour interaction with the host brain microenvironment. CRCTU Walker 256 cells showed greater incidence, larger tumour volume, pronounced blood–brain barrier disruption and prominent glial response when compared to ATCC cell line.ConclusionsThese findings indicate that immortalised cancer cell lines obtained from different cell banks may have diverse characteristics and behaviour in vivo.

Cognitive Deficits and Delayed Neuronal Loss in a Mouse Model of Multiple Microinfarcts

Microinfarcts are a common clinical feature of the aging brain, particularly in patients with cognitive decline or vascular or Alzheimer's dementia. However, the natural history of these lesions remains largely unexplored. Here we describe a mouse (C57BL/6J) model of multiple diffuse microinfarcts induced by unilateral internal carotid artery injection of cholesterol crystals (40-70 μm). Microinfarcts were spread throughout the deep cortex, subcortical tissue, and hippocampus and were comprised of a core positive for CD68 (a marker for reactive microglia and macrophages), surrounded by large regions of glial fibrillary acidic protein-positive reactive astrogliosis. Widespread reactive gliosis, including mislocalization of the astrocytic water channel aquaporin 4 persisted long after injury, recovering only after 1 month after stroke. Within the cortex, neuronal cell death progressed gradually over the first month, from ∼35% at 3 d to 60% at 28 d after stroke. Delayed demyelination was also observed in lesions, beginning 28 d after stroke. These findings demonstrate that microinfarct development follows a distinct course compared to larger regional infarcts such as those induced by middle cerebral artery occlusion. The long-lasting gliosis, delayed neuronal loss, and demyelination suggest that the therapeutic window for microinfarcts may be much wider (perhaps days to weeks) than for larger strokes.

Enhanced activation of RVLM-projecting PVN neurons in rats with chronic heart failure

Previous studies have indicated that there is increased activation of the paraventricular nucleus (PVN) in rats with chronic heart failure (CHF); however, it is not clear if the preautonomic neurons within the PVN are specifically overactive. Also, it is not known if these neurons have altered responses to baroreceptor or osmotic challenges. Experiments were conducted in rats with CHF (6-8 wk after coronary artery ligation). Spontaneously active neurons were recorded in the PVN, of which 36% were antidromically activated from the rostral ventrolateral medulla (RVLM). The baseline discharge rate in RVLM-projecting PVN (PVN-RVLM) neurons from CHF rats was significantly greater than in sham-operated (sham) rats (6.0 ± 0.6 vs. 2.6 ± 0.3 spikes/s, P < 0.05). Picoinjection of the N-methyl-D-aspartate (NMDA) receptor antagonist D,L-2-amino-5-phosphonovaleric acid significantly decreased the basal discharge of PVN-RVLM neurons by 80% in CHF rats compared with 37% in sham rats. Fifty-two percent of spontaneously active PVN-RVLM neurons responded to changes in the mean arterial pressure (MAP). The changes in discharge rate in PVN-RVLM neurons after a reduction in MAP (+52 ± 7% vs. +184 ± 61%) or an increase in MAP (-42 ± 8% vs. -71 ± 6%) were significantly attenuated in rats with CHF compared with sham rats. Most PVN-RVLM neurons (63%), including all barosensitive PVN-RVLM neurons, were excited by an internal carotid artery injection of hypertonic NaCl (2.1 osmol/l), whereas a smaller number (7%) were inhibited. The increase in discharge rate in PVN-RVLM neurons to hypertonic stimulation was significantly enhanced in rats with CHF compared with sham rats (134 ± 15% vs. 92 ± 13%). Taken together, these data suggest that PVN-RVLM neurons are more active under basal conditions and this overactivation is mediated by an enhanced glutamatergic tone in rats with CHF. Furthermore, this enhanced activation of PVN-RVLM neurons may contribute to the altered responses to baroreceptor and osmotic challenges observed during CHF.

E-053 Anomalous origin of the middle meningeal artery from mid-basilar artery

IntroductionThe middle meningeal artery (MMA) most commonly originates from the maxillary artery and travels through the foramen spinosum. Most variants have been noted to originate from the ophthalmic artery or...

Amelioration of endothelial damage/dysfunction is a possible mechanism for the neuroprotective effects of Rho-kinase inhibitors against ischemic brain damage

We investigated the neuroprotective effects of fasudil's active metabolite, hydroxyfasudil, a Rho-kinase inhibitor, in a rat stroke model in which endothelial damage and subsequent thrombotic occlusion were selectively induced in perforating arteries. By examining the effects on the endothelial damage/dysfunction, we thought to explore the mechanism of Rho-kinase inhibitors. Hydroxyfasudil (10 mg/kg, i.p., once daily for 3 days) significantly improved neurological functions and reduced the size of the infarct area produced by internal carotid artery injection of sodium laurate in a rat cerebral microthrombosis model. Treatment with fasudil or hydroxyfasudil concentration-dependently inhibited tumor necrosis factor α-induced tissue factor expression on the surface of cultured human umbilical vein endothelial cells. They also inhibited thrombin-induced endothelial hyperpermeability. The present findings suggest that hydroxyfasudil is efficacious in preventing brain damage associated with cerebral ischemia, and is partially responsible for fasudil's cytoprotective potential. The results also suggest that the therapeutic benefits against ischemic injury of Rho-kinase inhibitors are attributed, at least in part, to activity upon endothelial damage/dysfunction.

COMPARISON OF EXPERIMENTAL RAT MODELS OF EARLY BRAIN INJURY AFTER SUBARACHNOID HEMORRHAGE

To investigate acute pathophysiological changes after subarachnoid hemorrhage (SAH) in rats and compare endovascular perforation and double blood injection models for studies of early brain injury after SAH. Rat SAH was induced by endovascular perforation of the internal carotid artery (n = 41) or double injection of autologous blood into the cisterna magna (n = 23). Effects of SAH on arterial blood pressure, intracranial pressure, cerebral artery dimensions, and cerebral blood flow were measured. Neuronal death was assessed 24 hours after SAH. SAH was more severe in the endovascular perforation model (4-fold greater hemoglobin content on the basal brain surface), and mortality was greater (47%) than in the blood injection model (0%). Intracranial pressure increases were faster and greater in the perforation model. Correspondingly, cerebral blood flow reductions were greater after perforation than in the blood injection model, particularly in middle cerebral artery-supplied regions (32 +/- 16 versus 65 +/- 18 mL/100 g/min, P < 0.01). Diffuse neuronal death occurred in all rats in the perforation model but more seldom after blood injection. Anterior cerebral artery diameter and cross sectional area were significantly decreased on day 1 after SAH induction (52 +/- 21% and 22 +/- 16% of control values; P < 0.001) in the perforation model but not after blood injection. The perforation model produced more severe pathophysiological changes than the double blood injection, and it mimics human SAH in having an injured blood vessel and direct hemorrhagic brain lesion under arterial blood pressure. Therefore, endovascular perforation seems more suitable for study of acute SAH sequelae. However, further model refinement is required to reduce the high mortality rate.

Experimental Study on Targeted Methotrexate Delivery to the Rabbit Brain via Magnetic Resonance Imaging-Guided Focused Ultrasound

The purpose of this study was to investigate the effects of targeted and reversible disruption of the blood-brain barrier (BBB) by magnetic resonance imaging (MRI)-guided focused ultrasound (FUS) and delivery of methotrexate (MTX) to the rabbit brain. The brains of 20 rabbits were sonicated by MRI-guided FUS at different exposure times, and then Evans blue extravasation, contrast-enhanced MRI, and histologic examination were performed to determine the optimal exposure time for reversible BBB disruption with minimal damage. Five rabbits were sonicated at the optimal exposure time after MTX was injected intravenously (IV); the targeted locations were included in the sonicated group, and the nontargeted contralateral counterparts were included in the IV control group. Five other rabbits were not subjected to sonication and were administered internal carotid artery (ICA) injections of MTX; the specimens of the counterpart brain tissue were harvested as the ICA group. The MTX concentration in all of the specimens was determined by high-performance liquid chromatography. The MTX concentration in the sonicated group (mean +/- SD, 7.412 +/- 1.471 microg/g of tissue) was notably higher than that in both the IV control group (0.544 +/- 0.084 microg/g) and ICA group (1.984 +/- 0.65 microg/g; P <.01). Magnetic resonance imaging-guided FUS can disrupt the BBB reversibly and deliver IV administered MTX to targeted brain locations; it brings about a greater than 10-fold increase in the drug level and is much more effective (approximately 3.7-fold) than drug delivery through the ICA without sonication. This may facilitate the development of improved treatment methods for central nervous system disorders.

Antitumor activity of ZD6474 in a metastatic orthotopic brain tumor model

The objective of this study was to examine the antitumor effect of ZD6474, an orally available inhibitor of the vascular endothelial growth factor receptor-2 (VEGFR-2) and the epidermal growth factor receptor (EGFR), on tumor growth in an orthotopic metastatic brain tumor model. In order to determine the antitumor mechanism of ZD6474 treatment, in vitro and in vivo studies were performed. Human breast carcinoma cells (MDA-MB-435) were injected using direct intracranial (IC) inoculation (5x105 cells/100 µl) and internal carotid artery (ICA) injection (5x104 cells/100 µl) in Balb/c-nu female mice. Daily oral treatment with ZD6474 (50 mg/kg) was initiated on day 14 after the establishment of micrometastasis. Mice (n=12 per group) were sacrificed on day 28. Western blot analysis revealed that the autophosphorylation of EGFR and Akt was increasingly decreased with ZD6474 treatment in lung and brain endothelial cells and the MDA-MB-435 cell line. MTT assay also showed that the in vitro antitumor activity of ZD6474 was dependent on EGFR tyrosine kinase inhibition at a higher dose. Daily oral treatment with ZD6474 led to marked inhibition of metastatic tumor growth in the ICA injection and the direct IC inoculation models (median size 3.5 mm3, range 1.6-13.9 mm3) as compared to the control group (median size 62.4 mm3, range 11.5-206.9 mm3). These results suggest that simultaneous inhibition of both the EGFR and VEGFR-2 signaling pathways has a valuable therapeutic effect through its inhibition of the growth of metastatic brain tumors.

Comparison of metastatic brain tumour models using three different methods: the morphological role of the pia mater

As methods of cancer diagnosis and treatment progress, interest in metastatic brain tumours continues to increase. There are many studies using various methods of animal model and we considered that each model reflects different pathological processes because of the unique composition of the brain. We prepared metastatic brain tumour models using three different methods. In this study, we attempted to elucidate the roles of the pia mater in brain metastasis. The metastatic foci showed an angiocentric pattern, forming collars of neoplastic cells, and were designated 'perivascular proliferations'. Furthermore, we observed neoplastic cells that infiltrated the brain parenchyma, the border of which had become indistinct. These were labelled 'invasive proliferations'. The internal carotid artery injection model reflects haematogenous metastasis. In this model, both perivascular and invasive proliferations were observed. The intrathecal injection model reflects leptomeningeal carcinomatosis. In this model, metastasis to the meninges was observed. In the stereotactic injection model, the tumour proliferation at the injection site and the infiltration into the brain parenchyma were observed. The pia-glial membrane serves as a scaffold when neoplastic cells spread to the perivascular space forming angiocentric pattern. The pia-glial membrane is found between the brain parenchyma and blood vessels. Blood vessels penetrate the brain through tunnels known as perivascular spaces that are covered by pia mater. Three different methods which we prepared reflect three different pathological processes. Our findings suggest that the pia mater is a critical factor in brain metastasis.

5-HT activates vagal afferent cell bodies in vivo: Role of 5-HT 2 and 5-HT 3 receptors

Occipital artery (OA) injections of 5-HT elicit pronounced reductions in heart rate and mean arterial blood pressure (MAP) in urethane-anesthetized rats by activation of vagal afferent cell bodies in the ipsilateral nodose ganglion. In contrast, internal carotid artery (ICA) and i.v. injections elicit similar cardiovascular responses by activation of peripheral vagal afferent terminals. The aim of this study was to examine the roles of 5-HT 3 and 5-HT 2 receptors in the 5-HT-induced activation of vagal afferent cell bodies and peripheral afferent terminals in urethane-anesthetized rats. OA, ICA and i.v. injections of 5-HT elicited dose-dependent reductions in heart rate and MAP that were virtually abolished after i.v. administration of the 5-HT 3 receptor antagonists, MDL 7222 or ICS 205-930. The responses elicited by the OA injections of 5-HT were markedly diminished after i.v. injection of the 5-HT 2 receptor antagonists, xylamidine or ketanserin, whereas the responses elicited by i.v. or ICA injections of 5-HT were not affected. The present findings suggest that (1) 5-HT 3 and 5-HT 2 receptor antagonists gain ready access to nodose ganglion cells upon i.v. administration, and (2) functional 5-HT 3 and 5-HT 2 receptors exist on the cell bodies of vagal afferent neurons mediating the cardiovascular responses elicited by OA injections of 5-HT. These findings also support a wealth of evidence that 5-HT 3 receptors exist on the peripheral terminals of vagal afferents, and although they do not discount the possibility that 5-HT 2 receptors exist on peripheral vagal afferent terminals, it appears that activation of these receptors does not have pronounced effects on 5-HT 3 receptor activity on terminals that mediate the hemodynamic responses to 5-HT.