Congenital arachnoid cyst mimicking meningocele

The subject of this report is a rare case of a 5-year-old girl who developed an arachnoid cyst with a bony and dural defect in the parietal convexity. She had no history of head trauma or infection. Surgical exploration revealed the bulging lesion to consist of cerebrospinal fluid-containing spongy subcutaneous tissue and to extend into the bony and dural defect. The arachnoid cyst cavity was found beneath the subcutaneous lesion and was not connected to the adjacent subarachnoid space. Histologically, the subcutaneous tissue contained a complex of sinusoidal channels formed by an abundance of migrating arachnoidal cells, thus mimicking meningocele.

Accelerated reendothelialization with suppressed thrombogenic property and neointimal hyperplasia of rabbit jugular vein grafts by adenovirus-mediated gene transfer of C-type natriuretic peptide

BACKGROUND

Vein graft disease limits the late results of coronary revascularization. C-type natriuretic peptide (CNP) inhibits the growth of vascular smooth muscle cells. Given the effects of CNP on cGMP cascade, we hypothesized that transfected CNP genes modulate endothelial repair and thrombogenicity in the vein graft.

METHODS AND RESULTS

Autologous rabbit jugular vein grafts were incubated ex vivo in a solution of adenovirus vectors containing CNP gene (Ad.CNP) or Escherichia coli lac Z gene (Ad.LacZ) and then interposed in the carotid artery. Reendothelialization, mural thrombi formation, and intima/media ratio were evaluated on the 14th and 28th postoperative days. More reendothelialization was seen in Ad.CNP-infected grafts than in Ad.LacZ-infected grafts both at 14 days (0.81+/-0.05 versus 0.30+/-0.14, P<0.01) and at 28 days (0.96+/-0.01 versus 0.45+/-0.08, P<0.001). The mural thrombus area was smaller in Ad.CNP-infected grafts than in Ad.LacZ-infected grafts. Neointimal thickening was significantly suppressed in the Ad.CNP group. The in vitro wound assay with human coronary artery endothelial cells revealed significant potentiation of the wound repair process by CNP and atrial natriuretic peptide administration.

CONCLUSIONS

Infected Ad.CNP accelerated reendothelialization and suppressed thrombosis and neointimal hyperplasia. The method may potentially prevent vein graft disease in patients undergoing coronary artery revascularization.

MRI evaluation of the diaphragmal opening: using MRI parallel to the transsphenoidal surgical approach

Twenty-six adult diaphragma sellae and infundibulae were examined by MRI parallel to the transsphenonidal surgical plane with attention given to the diaphragmal opening. The diaphragmal opening was observed in 11 cases (42.3%). The anteroposterior diame ter of the opening ranged from 4.0 to 14.0 mm (mean 8.8 mm), and the lateral diameter ranged from 6.0 to 14.0 mm (mean 9.5 mm). In the cases of open diaphragma sellae, the infundibulum tended to be located in the posterior part of the diaphragma sellae but this was not statisticallysignificant. On MRI parallel to the transsphenoidal surgical approach, the anatomy of the dia phragma sellae was well evaluated.

Expression of E-cadherin-catenin complex in human benign schwannomas

The Ca2+-dependent cell adhesion molecule E-cadherin has been known to express in normal and reactive Schwann cells in rodents, and to play an important role in Schwann cell-Schwann cell adhesion and maintenance of peripheral nervous tissue architecture. However, little is known about expression of E-cadherin in schwannomas. The aim of the present study was to investigate the cellular expression and localization of E-cadherin, and its associated protein, alpha E-, alpha N- and beta-catenins in human schwannomas, which are supposed to derive from Schwann cells. We tested the hypothesis that these proteins might show an altered expression/distribution in schwannoma cells which correlates with their neoplastic behavior, including sparse cell-cell contact, as seen those in meningiomas and various carcinomas. In human schwannomas, however, E-cadherin, alpha E-catenin, and beta-catenin were detected by western blotting and immunohistochemistry, whereas alpha N-catenin was not. Immunoprecipitation using anti-E-cadherin antibody resulted in alpha E-catenin forming a complex with E-cadherin. SSCP analysis revealed no mutations in the transmembrane domain or in intracellular catenin-binding site of E-cadherin. These data suggest that the E-cadherin-alpha E-catenin complex is well preserved in human schwannoma cells, which is compatible with its benign behavior, and these molecules might be used as additional cell markers of Schwann cell-derived tumors.

Contrast-enhanced MR angiography (enhanced 3-D fast gradient echo) for diagnosis of cerebral aneurysms

We evaluated contrast-enhanced MRA (enhanced 3-D fast gradient echo, EFGRE3D, with spectral IR) for the identification of unruptured cerebral aneurysms. We examined 22 aneurysms from 15 patients. In its ability to identify aneurysms, contrast-enhanced MRA was superior to 3-D-time of flight (3D-TOF) MRA in 4 instances, equal in 17, and inferior in 1. Contrast-enhanced MRA demonstrated thrombus formation more clearly and accurately than did 3D-TOF MRA. Contrast-enhanced MRA was performed in less than 1 min, and was found to be a useful method for the identification of intracranial aneurysms.

Suppression of membrane-type 1 matrix metalloproteinase (MMP)-mediated MMP-2 activation and tumor invasion by testican 3 and its splicing variant gene product, N-Tes

Using expression cloning to screen a human fetal kidney cDNA library for regulator(s) of pro-matrix metalloproteinase (MMP)-2 processing mediated by membrane-type (MT) 1 MMP, we isolated a cDNA whose product interfered with pro-MMP-2 activation. It encodes the NH(2)-terminal 313-amino acid region of a calcium-binding proteoglycan, testican 3, with a 3-amino acid substitution at the COOH terminus and thus was named N-Tes. N-Tes comprises a signal peptide, a unique domain, a follistatin-like domain, and a Ca(2+)-binding domain but lacks a COOH-terminal thyroglobulin domain and two putative glycosaminoglycan attachment sites of testican 3. Pro-MMP-2 activation by MT3-MMP was also inhibited by the coexpression of N-Tes. Immunoprecipitation analysis demonstrated direct interaction of N-Tes with either MT1-MMP or MT3-MMP. Expression of testican 1 or testican 3 but not testican 2 also inhibited pro-MMP-2 activation by either MT1-MMP or MT3-MMP. Deletion and substitution of amino acids residues in N-Tes revealed that the unique NH(2)-terminal domain of N-Tes is responsible for the inhibition of pro-MMP-2 activation by MT-MMPs. Expression of N-Tes and testican 3 was detected in normal brain but down-regulated in glioma tissues. Transfection of either the N-Tes or testican 3 gene into U251 glioma cells or Madin-Darby canine kidney cells transformed by erbB2 suppressed their invasive growth in collagen gel. These results suggest that both N-Tes and testican 3 would interfere with tumor invasion by inhibiting MT-MMPs.

Surgical pathology of spinal schwannomas: a light and electron microscopic analysis of tumor capsules

OBJECTIVE

Although spinal schwannomas are often encountered, the pathology of the tumor capsule has not been reported. In this study, we describe the ultrastructural pathology of the tumor capsule of spinal schwannomas.

METHODS

In 18 patients who underwent total removal of spinal schwannomas (C2-conus), the tumor capsule was collected and examined by light and electron microscopy.

RESULTS

The thickness of the tumor capsule ranged from 15 to 800 microm (mostly 30-100 microm) and was composed of three layers from the surface to the center: 1) a thinly stretched nerve tissue layer; 2) a fibrous layer of fibrocytes, abundant collagen fibers, and tumor vessels; and 3) a thin transitional layer intermingled with fibrous components and tumor cells. The thickness of each layer varied in different regions of the surface. There was no clear separation between the tumor capsule and the neoplastic tissue, even on the electron microscopic level. A number of nerve fibers ran through the fibrous layer and beneath the capsule as well as in the nerve tissue layer.

CONCLUSION

Compared with vestibular schwannomas, which have been reported to be covered by an extremely thin layer (3-5 microm) of connective tissue, spinal schwannomas were well encapsulated. The capsule was composed of three distinct components; however, the cleavage between thin capsule and tumor cells was indistinct, and the thickness of the axon-containing capsule varied from site to site. Therefore, resection of the nerve of tumor origin, rather than enucleation, would be justified to avoid tumor recurrence. Surgeons should be aware of this pathology when performing the procedure.

Paramedian supracerebellar transtentorial approach for a medial tentorial meningioma with supratentorial extension: technical case report

OBJECTIVE AND IMPORTANCE

The choice of surgical approach to treat medial tentorial meningiomas is crucial and sometimes difficult to make. Although the subtemporal approach is most commonly used for lesions that extend mostly supratentorially, it risks injury to the vein of Labbé or the veins coursing along the subtemporal surface. To avoid venous injury, a medial tentorial meningioma was removed transtentorially through the infratentorial space via the paramedian supracerebellar transtentorial (PSCTT) approach.

CLINICAL PRESENTATION

A 35-year-old right-handed woman presented with a generalized convulsion. Magnetic resonance imaging scans revealed a left medial tentorial meningioma with supratentorial extension at the dominant hemisphere. The main venous drainage route from the ipsilateral temporal lobe was a sphenopetrosal vein.

INTERVENTION

An operation was performed with the patient in a sitting position, and the tumor was resected totally via the paramedian supracerebellar transtentorial approach without perioperative complications.

CONCLUSION

The paramedian supracerebellar transtentorial approach is useful for supratentorially located medial tentorial meningiomas without retraction of the temporal lobe and without damage to the vein of Labbé or the sphenopetrosal vein.

Calpain-dependent proteolysis of merlin occurs by oxidative stress in meningiomas: a novel hypothesis of tumorigenesis

BACKGROUND

The purpose of this study is to indicate that oxidative stress may contribute to occurrence of meningiomas. Recently, it was reported that aside from the neurofibromatosis type 2 (NF2) gene mutations, the calpain-dependent proteolysis of the NF2 gene product, merlin might be closely related to the development of certain NF2-related tumors. Although meningiomas are well known to occur more frequently in aged persons, it still remains unknown why calpain activation occurs predominantly in them. Because the production of free radicals with aging might be one of the causes of calpain activation especially in leptomeningeal cells being devoid of blood supply, the authors examined the relations between mu-calpain activation and merlin proteolysis induced by the oxidative stress.

METHODS

The authors examined 12 patient-derived sporadic meningiomas and their primary cultured cells. Malignant glioma cell line (U-251MG), which had no relation to NF2, was used as a control. They were exposed to hydrogen peroxide (H2O2) for 1 hour. After oxidative stress, they were examined by Western blot and immunofluorescence microscopic analyses.

RESULTS

Despite the consistent expressions of activated mu-calpain in 11 of 12 meningioma tissues, this calpain activation completely disappeared after culture; instead the full-length merlin appeared again in 8 of 11 cases. The treatment of cultured cells with hydrogen peroxide induced both mu-calpain-dependent cleavage of merlin and reduction of an intrinsic calpain inhibitor calpastatin. Such proteolysis was significantly blocked by a specific calpain inhibitor, Z-LLal. The full-length merlin was immunocytochemically colocalized with activated mu-calpain at the plasma membrane, and, after mu-calpain activation, the fragment of merlin translocated to the perinuclear cytoplasm or into the nucleus.

CONCLUSIONS

These findings suggest that oxidative stress-induced activation of mu-calpain causes proteolysis of merlin conceivably to impair cell adhesion and/or contact inhibition of meningioma cells.

Contrast-enhanced fluid-attenuated inversion recovery MRI is useful to detect the CSF dissemination of glioblastoma

We present three cases of glioblastoma with CSF dissemination that contrast-enhanced fluid-attenuated inversion recovery MRI was sensitive enough to detect compared with contrast-enhanced T1-weighted MRI. An autopsy was performed on one patient, and its histologic findings proved the existence of CSF dissemination.

Expression of dominant-negative form of Ets-1 suppresses fibronectin-stimulated cell adhesion and migration through down-regulation of integrin alpha5 expression in U251 glioma cell line

Ets transcription factors are associated with tumor malignancy. We reported previously that the stable transfection of the dominant-negative form of Ets-1 (Ets-DN) in the glioma cell line U251 induced down-regulation of urokinase-type plasminogen activator mRNA expression and invasiveness (M. Nakada et al., J. Neuropathol. Exp. Neurol., 58: 329-334, 1999). Here we analyzed effects of Ets-DN expression on cell adhesion, migration, and phosphorylation of focal adhesion kinase. U251 cells expressing Ets-DN (U251-DN) showed reduced cell adhesion, spreading, and extension of actin stress fibers on dishes coated with fibronectin but not on dishes coated with collagen. Migration of U251-DN cells was found to be significantly inhibited compared with that of parental cells when examined by wound-induced migration assay on fibronectin-coated dishes. Phosphorylation levels of focal adhesion kinase in U251-DN cells were also attenuated on dishes coated with fibronectin. Reduced expression level of integrin alpha5 subunit in U251-DN cells was demonstrated by semiquantitative reverse transcription-PCR analysis. Semiquantitative reverse transcription-PCR of surgical samples of brain tumors revealed that the expression level of Ets-1 mRNA correlated with that of integrin alpha5 mRNA in glioma. The experimental metastatic ability of U251-DN cells examined in chick embryo was considerably lower than that of parental cells. These results suggest that Ets-1 contributes to glioma malignancy by up- regulating expression of the integrin alpha5 subunit, which composes integrin alpha5beta1 and mediates intracellular signaling and the subsequent acceleration of the invasive process, including cell adhesion and migration.

Homozygous deletion of INK4a/ARF genes and overexpression of bcl-2 in relation with poor prognosis in immunocompetent patients with primary central nervous system lymphoma of the diffuse large B-cell type

Only a few reports have been published on molecular genetic alterations in primary central nervous system lymphomas (PCNSLs) of the diffuse large B-cell type and no reports have addressed the correlation between the genetic alterations and clinical course of the patients with this neoplasm. Thus, the molecular background of the PCNSL and its importance for the clinical course of the patients are still unclear. We investigated a series of 14 patients with PCNSL to determine structural alterations of the INK4a/ARF, MDM2, and TP53 genes, the status of bcl-2 and bcl-6 protein expression, and the clinical course of the patients (i.e. their survival time after diagnosis). No structural alterations of MDM2 and TP53 genes were found. Only INK4a/ARF genes whose expression affects both the p161NK4a-Rb and p14ARF-mdm2-p53 pathways in the regulation for cell cycle and apoptosis, showed an alteration of the homozygous deletions at a high frequency (nine of 14 patients: 64%). This specific alteration was not related with the bcl-6 expression, but a relation was shown with overexpression of the bcl-2 anti-apoptotic protein (p = 0.036, chi-square test), as well as a shorter patient survival (p = 0.044, Wilcoxon test). There was only a tendency, not a significant correlation, in which the patients with bcl-2 overexpression resulted in poor prognosis (p = 0.149). The present study is the first to suggest that the INK4a/ARF gene homozygous deletions and overexpression of the bcl-2 protein may be correlated with each other and together serve as important predictors for the prognosis of patients with PCNSL.

Coordinate regulation of endothelin and adrenomedullin secretion by oxidative stress in endothelial cells

To elucidate the significance of oxidative stress in the modulation of endothelial functions, we examined the effects of H(2)O(2) on the expression of two endothelium-derived vasoactive peptides, endothelin (ET) and adrenomedullin (Am), and their interaction. H(2)O(2) dose dependently suppressed ET secretion and ET-1 mRNA expression in bovine carotid endothelial cells (ECs). Menadion sodium bisulfate, a redox cycling drug, also decreased ET secretion in a dose-dependent manner. Catalase, a H(2)O(2) reductase, and dl-alpha-tocopherol (vitamin E) significantly inhibited H(2)O(2)-induced suppression of ET secretion. Downregulation of ET-1 mRNA under oxidative stress was regulated at the transcriptional level. In contrast, H(2)O(2) increased Am secretion (and its mRNA expression) accompanied by the augmentation of cAMP production. Am, as well as 8-bromo-cAMP and forskolin decreased ET secretion in a dose-dependent fashion. Furthermore, an anti-Am monoclonal antibody that we developed abolished H(2)O(2)-induced suppression of ET secretion at 6-24 h after the addition of H(2)O(2). H(2)O(2) increased the intracellular Ca(2+) concentration ([Ca(2+)](i)). Moreover, treatment with ionomycin, a Ca(2+) ionophore, and thapsigargin, an inhibitor of endoplasmic reticulum ATPase, decreased ET secretion dose dependently for 3 h. These results suggest that the production of ET was decreased via activation of the Am-cAMP pathway and by the elevation of [Ca(2+)](i) under oxidative stress. These findings elucidate the coordinate expression of two local vascular hormones, ET and Am, under oxidative stress, which may protect against vascular diseases.

Thiazolidinediones, peroxisome proliferator-activated receptor gamma agonists, regulate endothelial cell growth and secretion of vasoactive peptides

Insulin resistance has been highlighted as a common causal factor for glucose intolerance, hypertension and dyslipidemia, all of which are cardiovascular risk factors. A new class of antidiabetic agents, thiazolidinediones (TZDs), has been developed and demonstrated to improve insulin sensitivity. TZDs are high affinity ligands for peroxisome proliferator-activated receptor gamma (PPARgamma), the crucial transcription factor for adipocytes. Recent studies showed that PPARgamma is also expressed in monocytes/macrophages and is suggested to be involved in atherosclerosis. We could detect PPARgamma gene transcript in several cultured endothelial cells (human aortic endothelial cells (HAoECs), human coronary artery endothelial cells (HCAECs), human umbilical vein endothelial cells (HUVECs) and bovine carotid artery endothelial cells (BAECs)) as well as human coronary arteries we examined. Since endothelial dysfunction is critical for atherosclerosis, we investigated the effects of TZDs, troglitazone (TRO) and pioglitazone (PIO), on endothelial cell growth and secretion of C-type natriuretic peptide (CNP), which we demonstrated as a novel endothelium-derived relaxing peptide, and endothelin (ET), a potent vasoconstrictor, using HAoECs, HCAECs, HUVECs and BAECs. When all these cultured endothelial cells were daily treated with TRO and PIO for 5 days, both TRO and PIO (10(-8)M) significantly stimulated (3)H-thymidine incorporation of all these endothelial cells. In contrast, higher dose of TRO and PIO (10(-5)M) significantly suppressed DNA synthesis. TRO and PIO also exerted the compatible effect on the increase of cell numbers. TRO and PIO significantly enhanced CNP secretion from BAECs. In contrast, ET secretion from BAECs was suppressed by both TRO and PIO in a dose-dependent manner. The results of the present study suggest that TZDs modulate endothelial functions, including regulation of endothelial cell growth and secretion of endothelium-derived vasoactive substances, which affect vascular tone and remodeling in the process of atherosclerosis.

CT during selective arteriography: anatomical assessment of unruptured intracranial aneurysms before endovascular treatment

Our aim was to investigate the usefulness of helical CT during selective angiography (CT arteriography) in pretreatment assessment of unruptured intracranial aneurysms. We studied 47 unruptured aneurysms in 34 prospectively recruited patients for whom endovascular embolisation was initially considered. As pretreatment assessment, we performed rotational digital subtraction angiography (DSA) followed by CT arteriography. The findings on axial source images (axial images) and reconstructed three-dimensional CT angiography (3D-CTA) of CT arteriography were compared to those of rotational DSA, with particular attention to the neck of the aneurysm and arterial branches adjacent to it. Information provided by CT arteriography was more useful than that of rotational DSA as regards the neck in 25 (53%) of 47 cases and as regards branches in 18 (49%) of 37 aneurysms. On axial images, small arteries such as the anterior choroidal artery were seen in some cases. CT arteriography can provide valuable additional information about unruptured aneurysms, which cannot be obtained by rotational DSA alone. This technique is useful for obtaining anatomical information about aneurysm anatomy and for deciding the therapeutic strategy.

Blood-brain barrier transport of H1-antagonist ebastine and its metabolite carebastine

The transport mechanism of the non-sedative H1-antagonist ebastine and its first-pass carboxylic acid metabolite carebastine at the blood-brain barrier (BBB) was studied. In rats, the brain uptake index (BUI) value of [14 C]carebastine was significantly lower than that of [14 C]ebastine. The BUI value of [14 C]carebastine was greatly increased by the addition of non-labeled carebastine. The steady-state uptake of [14 C]carebastine by P-glycoprotein-overexpressing K562/ADM cells was significantly lower than that by their parental drug-sensitive cell line K562. The decreased steady-state uptake of [14 C]carebastine by K562/ADM cells was reversed by verapamil. Steady-state uptake of [14 C]carebastine by primary cultured bovine brain capillary endothelial cells (bovine BCECs) was increased in the presence of metabolic inhibitors and verapamil. Non-labeled carebastine increased the steady-state uptake of a P-glycoprotein substrate, [3 H]vincristine, by bovine BCECs. The initial uptake of [3 H]mepyramine by bovine BCECs and RBEC1 (an immortalized cell line from rat brain capillary endothelial cells) was strongly inhibited by ebastine, while zwitterionic carebastine was slightly inhibitory. The values of brain-to-plasma unbound concentration ratio (Kp,f) in mdr1a(-/-) mice were increased 5.3-fold and 4.2-fold for [14 C ebastine and for [14 C]carebastine, respectively, compared with those in mdr1a(+/+) mice. Non-radiolabeled carebastine increased the Kp,f values of [14 C]carebastine in both types of mice. In conclusion, carebastine was shown to be a substrate for P-glycoprotein-mediated efflux from the brain at the BBB. A second efflux system may also be involved. The relatively low affinity of the uptake transport system for carebastine also limits the brain distribution of ebastine/carebastine.

Malignant transformation of a gangliocytoma/ganglioglioma into a glioblastoma multiforme: a molecular genetic analysis. Case report

A gangliocytoma/ganglioglioma with no atypical or malignant features was subtotally resected from the right temporal lobe of a 16-year-old woman. A second resection was performed 8 years later to treat a locally recurrent lesion with increased cellularity that was diagnosed as a World Health Organization Grade II ganglioglioma on the basis of neuropathological examination. Molecular analysis of the recurrent tumor revealed a TP53 gene mutation, but no amplification of the epidermal growth factor receptor (EGFR) gene. Radiotherapy (60 Gy) was administered after the second resection. The patient returned 1 year later with a second focal recurrence. The specimen obtained during the third resection of tumor exhibited exclusively astrocytic differentiation, cellular pleomorphism with multinucleated cells, high mitotic activity, and endothelial proliferation. Therefore, the tumor was diagnosed to be a glioblastoma multiforme (GBM). Molecular analysis of tumor DNA from the second recurrent tumor demonstrated the presence of the TP53 mutation, which previously had been observed in the first recurrent tumor, but again no evidence of EGFR amplification. Findings demonstrate that the presence of TP53 mutation in progressed gangliogliomas should be interpreted as a progression-associated mutation rather than a consequence of treatment. This is the first report to indicate that the molecular pathways of gangliocytomas/gangliogliomas progressing to become GBMs may parallel those of diffuse astrocytomas progressing to become GBMs.

Improved cerebral perfusion and metabolism after stenting for basilar artery stenosis: technical case report

OBJECTIVE

Recent advances in stent technology have allowed the introduction of more flexible stents that may be tracked more easily in the intracranial vessels. We present a patient with improved cerebral blood flow and metabolism as assessed by positron emission tomography after stent-assisted angioplasty for symptomatic basilar artery stenosis.

CLINICAL PRESENTATION

A 62-year-old man, who had undergone left superficial temporal artery to middle cerebral artery bypass surgery for left internal carotid artery occlusion 10 years previously, presented with dizziness, blurred vision, and memory disturbance. Angiography revealed severe stenosis of the proximal basilar artery. Positron emission tomographic scans revealed decreased cerebral blood flow associated with increased oxygen extraction fraction in the entire brain, particularly in the posterior circulation and the left middle cerebral artery territory. Despite medical treatment, the patient experienced worsening visual disturbance and right-sided motor weakness.

INTERVENTION

Ticlopidine and aspirin were used as antiplatelet agents. In addition, we used argatroban, which is a direct thrombin inhibitor, as an anticoagulant during the procedure. Predilation with a coronary artery balloon was performed, followed by placement of a GFX 3- by 8-mm stent (Arterial Vascular Engineering, Santa Rosa, CA), with excellent angiographic results. The patient made a good neurological recovery, and the postoperative positron emission tomographic scan demonstrated increases in both cerebral blood flow and cerebral metabolic rate of oxygen with a normalization of oxygen extraction fraction.

CONCLUSION

Stent-assisted angioplasty can provide a favorable clinical course as well as improved cerebral perfusion and metabolism for a patient with basilar artery stenosis. Long-term follow-up data and additional clinical experience are required to assess the durability of this approach.

C-type natriuretic peptide induces redifferentiation of vascular smooth muscle cells with accelerated reendothelialization

We recently reported that C-type natriuretic peptide (CNP) occurs in vascular endothelial cells and acts as a vascular-type natriuretic peptide. In the present study, we stimulated the cGMP cascade in proliferating smooth muscle cells (SMCs), in which particulate guanylate cyclase-B, the specific receptor for CNP, is predominantly expressed, by use of an adenovirus encoding rat CNP cDNA (Ad.CNP). In the Ad.CNP-treated cultured SMCs, CNP caused the growth inhibition of SMCs at G(1) phase with an early increase of p21(CIP1/WAF1) expression and subsequent upregulation of p16(INK4a). The expression of smooth muscle myosin heavy chain-2, which is the molecular marker of highly differentiated SMCs, was reinduced in the Ad.CNP-treated SMCs. The Ad.CNP-treated SMCs also reexpressed particulate guanylate cyclase-A, which shows high affinity to atrial and brain natriuretic peptide and is exclusively expressed in well-differentiated SMCs. CNP, which was overexpressed in rabbit femoral arteries in vivo at the time of balloon injury, significantly suppressed neointimal formation. Furthermore, an enhancement of the expression of smooth muscle myosin heavy chain-2 occurred in the residual neointima. In addition, early regeneration of endothelial cells was observed in the Ad.CNP-infected group. Thus, stimulation of cGMP cascade in proliferating dedifferentiated SMCs can induce growth inhibition and redifferentiation of SMCs with accelerated reendothelialization.

The use of dynamic mechanical analysis to assess the viscoelastic properties of human cortical bone

The purpose of this study was to examine the use of a dynamic mechanical analyzer (DMA) system to study the viscoelastic nature of bone. Cortical bone specimens from human femora were tested isothermally for 150 min at 37 degrees C and the loss factor (tan delta) and storage modulus (E') were measured. To explore the effects of test conditions on tan delta and E', different levels of applied stress, two specimen sizes, and two hydration conditions (wet and vacuum-dried) were evaluated. Finally, nonisothermal tests were performed, wherein specimens were heated up to 70 degrees C at different heating rates: 1 degrees C/min, 3 degrees C/min, and 5 degrees C/min. The results indicated that a threshold level of minimum applied stress was required to obtain repeatable and relatively constant values of tan delta. Specimen size did not significantly affect tan delta although it influenced E'. Moisture content had a significant effect on tan delta; vacuum-dried specimens exhibited a lower tan delta compared to wet specimens. Lastly, heating rates influenced tan delta values with lower rates producing more consistent results. The study demonstrated that DMA can be used as an effective tool to test bone.

Aneurysm clipping after partial endovascular embolization for ruptured cerebral aneurysms

SUMMARY

The aim of this study was to investigate the advantages and disadvantages of a two-stage treatment for ruptured cerebral aneurysms; partial embolization in acute stage followed by clipping in chronic stage of subarachnoid hemorrhage. Between April 1997 and August 1999, twenty ruptured cerebral aneurysms were initially treated endovasculary using Guglielmi detachable coils in our institution. Among them, complete embolization could not be achieved in 6 lesions. For these lesions, subsequent clipping was added. The radiological and operative findings, and outcomes of these cases were retrospectively reviewed. In 1 case, rerupture occurred during the endovascular procedure. Rerupture was not observed in any cases in the postembolization period. In 2 cases, complications related to the clipping but not the endovascular procedure occurred. These complications included impaired visual acuity for unverified reasons, and memory disturbance due to sacrifice of a perforator arising from the anterior communicating artery. In 3 cases, coil extraction was needed during the clipping, because the loops of the coil extended into the residual neck. Complications related to coil extraction were not observed in these 3 cases. Acute partial embolization of ruptured aneurysm appears to be effective for the prevention of subsequent rerupture during the subacute period, in which treatment for vasospasm should be performed, and the clipping procedure. However, in the case of relatively large aneurysms, small arteries or other normal structures behind the aneurysm cannot be observed directly during surgery, because of the immovability of the embolized aneurysm. Further, complete clip closure is impossible when loops of coil herniate into the neck. In such situations, coil extraction with or without resection of the aneurysm might be necessary, and care must be taken not to damage parent artery and surrounding vessels.

Significance of volume embolization ratio as a predictor of recanalization on endovascular treatment of cerebral aneurysms with guglielmi detachable coils

SUMMARY

The purposes of this study are, firstly, to define the relationship between volume embolization ratio (VER) and degree of angiographical occlusion in endovascular treatment with Guglielmi detachable coils, and secondly, to examine influences of neck and dome sizes of aneurysms on the VER and the angiographical treatment result, and thirdly, to determine the relationship between the VER and the recanalization of coiled aneurysms. Fifty-two aneurysms in 46 patients were examined. VER ranged 8.1-31.9% (mean 18.5%). The mean VERs of each categories based on angiographical treatment results were 23.1% in complete occlusion, 16.1% in neck remnant and 12.2% in incomplete occlusion, respectively. The VER correlated significantly with both neck and dome size, while the angiographical treatment result was only affected by neck size. Five aneurysms showed aneurysmal recanalization among followed-up 41 aneurysms. All recanalized aneurysms were large, and their VERs were in range of 10.4-17.6%. Measurement of VER is useful to estimate the degree of occlusion objectively and to predict the aneurysmal recanalization. A small aneurysms with a small neck is relatively easy to achieve high VER and angiographical complete occlusion, with the consequence of less recanalization. On the other hand, a large aneurysm is liable to recanalize due to low VER, even if there was little filling of contrast medium in the aneurysmal cavity.

Roles of membrane type 1 matrix metalloproteinase and tissue inhibitor of metalloproteinases 2 in invasion and dissemination of human malignant glioma

OBJECT

Acquisition of invasive and metastatic potentials through proteinase expression is an essential event in tumor progression. Among proteinases, matrix metalloproteinases (MMPs) are thought to play a key role in tumor progression through the degradation of the extracellular matrix. In the present study, the authors examined the role of MMP-2 (gelatinase A) and membrane type 1 MMP (MT1-MMP), an activator of the zymogen of MMP-2, proMMP-2, together with tissue inhibitors of metalloproteinases (TIMP-1 and TIMP-2) in the invasion of astrocytic tumors in humans.

METHODS

Analyses performed using sandwich enzyme immunoassays demonstrated that the production levels of pro-MMP-2 and TIMP-1, but not TIMP-2, are significantly higher in glioblastomas multiforme than in other grades of astrocytic tumors. Quantitative reverse transcription-polymerase chain reaction indicated that MT1-MMP is expressed predominantly in glioblastoma tissues, and its expression levels are significantly enhanced as tumor grade increases. In addition, the expression levels and proMMP-2 activation ratio were remarkably higher in glioblastomas associated with cerebrospinal fluid (CSF) dissemination than in those not associated with CSF dissemination. In contrast, an examination of TIMP-2 levels showed a reverse correlation. Like MT1-MMP, TIMP-1 and TIMP-2 were immunolocalized to neoplastic cells in glioblastoma samples. To study the roles of these molecules in the invasion of astrocytic tumors more fully, stable transfectants expressing the MT1-MMP gene were developed in a U251 human glioblastoma cell line. The MT1-MMP transfectants displayed prominent activation of proMMP-2 and invasive growth in three-dimensional collagen gel; however, mock transfectants and parental cells displayed noninvasive growth without the activation. The invasion and gelatinolytic activity of the transfectants were completely inhibited by addition of recombinant TIMP-2, but not recombinant TIMP-1.

CONCLUSIONS

These results indicate that MT1-MMP may contribute to tumor invasion and CSF dissemination of glioblastoma cells on the basis of an imbalance of TIMP-2.

KB-R7943, a selective Na+/Ca2+ exchange inhibitor, protects against ischemic acute renal failure in mice by inhibiting renal endothelin-1 overproduction

We investigated whether the preischemic or postischemic treatment with KB-R7943, a novel and selective Na+/Ca2+ exchange inhibitor, has renal protective effects in mice with ischemic acute renal failure (ARF). Ischemic ARF was induced by clamping the left renal pedicle for 45 min followed by reperfusion, 2 weeks after contralateral nephrectomy. Renal function was markedly diminished 24 h after reperfusion. Preischemic treatment with KB-R7943 attenuated the ARF-induced renal dysfunction. The ischemia/reperfusion-induced renal dysfunction was also overcome by postischemic treatment with KB-R7943. Histopathologic examination of the kidneys of ARF mice revealed severe renal damage such as tubular necrosis, proteinaceous casts in tubuli, and medullary congestion. Histologically evident damage and Ca2+ deposition in necrotic tubular epithelium were improved by preischemic treatment with KB-R7943. In addition, preischemic treatment with KB-R7943 significantly suppressed the increment of endothelin-1 (ET-1) content in the kidney at 2, 6, and 24 h after reperfusion. These findings suggest that Ca2+ overload via the reverse mode of Na+/Ca2+ exchange, followed by renal ET-1 overproduction, plays an important role in the pathogenesis of the ischemia/reperfusion-induced ARF. KB-R7943 may prove to be an effective therapeutic agent for cases of ischemic ARF in humans.

Pre- or post-ischemic treatment with a novel Na+/Ca2+ exchange inhibitor, KB-R7943, shows renal protective effects in rats with ischemic acute renal failure

We investigated the effects of pre- or post-ischemic treatment with KB-R7943, a new Na+/Ca2+ exchange inhibitor, on ischemic acute renal failure (ARF) in rats, and these were compared with the effects of verapamil. Ischemic ARF was induced by clamping the left renal pedicle for 45-min followed by reperfusion, 2 weeks after contralateral nephrectomy. Renal function markedly decreased 24 h after reperfusion. Pre-ischemic treatment with KB-R7943 or verapamil attenuated the ARF-induced renal dysfunction. The ischemia/reperfusion-induced renal dysfunction was overcome by post-ischemic treatment with KB-R7943 but not with verapamil. Histopathological examination of the kidney of ARF rats revealed severe renal damage, and suppression of the damage was seen with post-ischemic treatment with KB-R7943. KB-R7943 markedly suppressed the increment of endothelin-1 (ET-1) content in the kidney at 2, 6, and 24 h after reperfusion. No significant changes in Na+/Ca2+ exchanger protein expression in renal tissue were observed with 45-min ischemia, 6 h after reperfusion and KB-R7943 treatment. These results suggest that Ca2+ overload via the reverse mode of Na+/Ca2+ exchange, followed by ET-1 overproduction, seems to play an important role in the pathogenesis of the ischemia/reperfusion-induced ARF. KB-R7943, which is effective in both cases of pre- and post-ischemic treatments, may prove to be an effective therapeutic agent for cases of ischemic ARF.

cGMP-dependent protein kinase phosphorylates and inactivates RhoA

Small GTPase Rho and cGMP/cGMP-dependent protein kinase (cGK) pathways exert opposing effects in specific systems such as vascular contraction and growth. However, the direct interaction between these pathways has remained elusive. We demonstrate that cGK phosphorylates RhoA in vitro at Ser188, the same residue phosphorylated by cAMP-dependent protein kinase. In HeLa cells transfected with constitutively active cGK (C-cGK), stress fiber formation induced by lysophosphatidic acid or V14RhoA was blocked. By contrast, C-cGK failed to inhibit stress fiber formation in cells transfected with mutant RhoA with substitution of Ser188 to Ala. C-cGK did not affect actin reorganization induced by Rac1 or Rho-associated kinase, one of the effectors for RhoA. Furthermore, C-cGK expression inhibited the membrane translocation of RhoA. Collectively, our findings suggest that cGK phosphorylates RhoA at Ser188 and inactivates RhoA signaling. The physiological relevance of the direct interaction between RhoA and cGK awaits further investigation.

Serial neuroimaging of a growing thrombosed giant aneurysm of the distal anterior cerebral artery--case report

An 81-year-old female presented with a giant aneurysm of the distal anterior cerebral artery (A3) which grew from a small saccular aneurysm to a huge aneurysm within 36 months before manifesting as a mass lesion. The thrombosed portion of the aneurysm showed growth, whereas the aneurysmal cavity did not change in size. Computed tomography and magnetic resonance imaging showed new bleeding in the thrombosed portion. Hemorrhage into the thrombus and/or aneurysmal wall might have caused the aneurysmal growth. She refused surgery and was discharged with no deficits. Distal anterior cerebral artery aneurysm which shows neuroimaging signs of growth requires regular follow up as such lesions may become giant before manifesting clinical symptoms.

Ruptured irregularly shaped aneurysms: pseudoaneurysm formation in a thrombus located at the rupture site

OBJECT

The authors describe the clinical, radiological, and pathological findings of ruptured cerebral aneurysms with irregular configurations.

METHODS

Eight patients with subarachnoid hemorrhage due to ruptured irregularly shaped aneurysms were examined. The preoperative radiological findings in these cases were compared with the pathological and operative findings of endovascular or open surgery. All of the aneurysms exhibited delayed opacification and delayed washout of contrast medium from the irregularly shaped portion of the aneurysm on digital subtraction angiography and/or helical computerized tomography scanning. Endovascular embolization with platinum coils was attempted in the first four patients who underwent treatment. In three of these patients the aneurysm ruptured again during the endovascular procedure. In the fourth patient an intraaneurysm thrombus was observed during the procedure and clipping was performed. In the subsequent four patients, three underwent clipping without complication and one underwent partial aneurysm embolization because of poor general status. A thrombus adjacent to the aneurysm dome was observed in the patients who underwent open surgery. Pathological examination of the operative specimens revealed a pseudoaneurysm-like cavity in the thrombus that was adherent to the aneurysm.

CONCLUSIONS

Ruptured irregularly shaped aneurysms may be accompanied by fragile pseudoaneurysm-like cavities located at the rupture point. Because these aneurysms have a high risk of repeated rupture during an endovascular procedure, advancing microinstruments to the weaker portion of the aneurysm should be avoided.

Flk1-positive cells derived from embryonic stem cells serve as vascular progenitors

Interaction between endothelial cells and mural cells (pericytes and vascular smooth muscle) is essential for vascular development and maintenance. Endothelial cells arise from Flk1-expressing (Flk1+) mesoderm cells, whereas mural cells are believed to derive from mesoderm, neural crest or epicardial cells and migrate to form the vessel wall. Difficulty in preparing pure populations of these lineages has hampered dissection of the mechanisms underlying vascular formation. Here we show that Flk1+ cells derived from embryonic stem cells can differentiate into both endothelial and mural cells and can reproduce the vascular organization process. Vascular endothelial growth factor promotes endothelial cell differentiation, whereas mural cells are induced by platelet-derived growth factor-BB. Vascular cells derived from Flk1+ cells can organize into vessel-like structures consisting of endothelial tubes supported by mural cells in three-dimensional culture. Injection of Flk1+ cells into chick embryos showed that they can incorporate as endothelial and mural cells and contribute to the developing vasculature in vivo. Our findings indicate that Flk1+ cells can act as 'vascular progenitor cells' to form mature vessels and thus offer potential for tissue engineering of the vascular system.

De novo spinal teratoma after treatment of an intracranial germ cell tumor

The authors report an extremely rare case of de novo spinal teratoma after treatment for intracranial germ cell tumor. A 17-year-old male developed pain of bilateral lower extremities and urinary retention 18 months after complete remission of intracranial mixed germ cell tumor. Magnetic resonance imaging revealed a huge spinal tumor associated with spina bifida occulta. Total resection was performed, and histogenetical findings led to the diagnosis of a mature teratoma with normal p16 gene, whereas analysis of intracranial tumor showed p16 deletion. The spinal anomaly and genetic analysis strongly suggest that the spinal teratoma was a de novo tumor rather than a metastasis or dissemination of the original intracranial germ cell tumor.

Increased expression of deoxyribonucleic acid methyltransferase gene in human astrocytic tumors

The relationship between the grade of astrocytic tumor and the expression of deoxyribonucleic acid methyltransferase (DNA-MTase) gene was examined. The levels of DNA-MTase messenger ribonucleic acid (mRNA) were measured by semiquantitative reverse transcriptase-polymerase chain reaction in surgical specimens from 12 astrocytic tumors (4 astrocytomas, 6 anaplastic astrocytomas, and 2 glioblastomas) and two normal brain tissues, and in four glioma cell lines. Compared to normal brain tissues, the levels of DNA-MTase mRNA were increased by 16- to 55-fold in low grade astrocytomas, and significantly increased by 200- to 4500-fold in high grade astrocytomas (anaplastic astrocytomas and glioblastomas) and more than 4500-fold in glioma cell lines. In situ hybridization with paraffin-embedded surgical specimens of human astrocytic tumors showed DNA-MTase mRNA was abundantly expressed in high grade astrocytomas. The detection of increased DNA-MTase expression in astrocytic tumor indicates involvement in the tumorigenesis and suggests that blocking of this change with specific inhibitors may offer new therapeutic strategies for malignant astrocytic tumors.

Limited distribution of new quinolone antibacterial agents into brain caused by multiple efflux transporters at the blood-brain barrier

Transport of new quinolone antibacterial agents (quinolones) at the blood-brain barrier (BBB) was studied in vitro by using immortalized rat brain capillary endothelial cells RBEC1, and in vivo by using the brain perfusion method in rats and multidrug-resistant mdr1a/1b gene-deficient mice. The permeability coefficient of grepafloxacin measured by brain perfusion was increased by an excess of unlabeled grepafloxacin, suggesting a participation of a saturable BBB efflux system. Uptake coefficients of [(14)C]grepafloxacin, [(14)C]sparfloxacin, and [(14)C]levofloxacin by RBEC1 cells at the steady state were increased in the presence of the unlabeled quinolones. The steady-state uptake of [(14)C]grepafloxacin was increased in the presence of various quinolones. Brain distributions of [(14)C]grepafloxacin and [(14)C]sparfloxacin evaluated in terms of the brain-to-plasma free concentration ratio in mdr1a/1b gene-deficient mice were significantly higher than those in wild-type mice, demonstrating an involvement of P-glycoprotein as the efflux transporter. Anionic compounds, including 4, 4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS) and genistein, increased the steady-state uptake of [(14)C]grepafloxacin by RBEC1 cells. Because [(14)C]grepafloxacin was transported by multidrug resistance-associated protein (MRP), in MRP1-overexpressing cells and because RBEC1 and primary cultured brain capillary endothelial cells expressed MRP1, this protein may be an additional efflux transporter for quinolones. Furthermore, the permeability coefficient of [(14)C]grepafloxacin across the BBB was increased by DIDS or in the absence of bicarbonate ions in the brain perfusion method. DIDS or bicarbonate ion did not affect MRP1 function. Accordingly, the brain distribution of quinolones is restricted by the action of multiple efflux transporters, including P-glycoprotein, MRP1, and an unknown anion exchange transporter.

Altered gene expression of uncoupling protein-2 and -3 in stroke-prone spontaneously hypertensive rats

BACKGROUND

Uncoupling proteins (UCPs) are the inner mitochondrial membrane-associated proteins, which dissipate the proton gradient and generate heat instead of ATP. The involvement of UCPs in energy expenditure and glucose metabolism has been suggested. Recently, we succeeded in cloning of rat UCP2 and UCP3.

OBJECTIVE

The aim of this study was to elucidate the pathophysiological role of UCP2 and UCP3 in hypertension associated with hyperglycemia in stroke-prone spontaneously hypertensive rats (SHR-SP).

METHODS

UCP2 and UCP3 mRNA levels of cardiac and gastrocnemius muscles in SHR-SP and Wistar-Kyoto (WKY) rats were determined at 6 weeks (prehypertensive stage) and at 15 weeks (hypertensive stage).

RESULTS

UCP2 and UCP3 mRNA levels in the heart of SHR-SP at 6 weeks were significantly higher than those of WKY rats (1.6-fold, 3.6-fold, respectively). These tendencies did not change in the heart at 15 weeks. UCP2 and UCP3 mRNA levels in the skeletal muscle of SHR-SP at 6 weeks were significantly higher than those of WKY rats (1.4-fold, 2.4-fold, respectively). In contrast, at 15 weeks, UCP2 and UCP3 mRNA levels in the skeletal muscle of SHR-SP were significantly lower than those of WKY rats (70 and 36% of WKY rats, respectively). Therefore, the decrease of UCP2 and UCP3 in the skeletal muscle was observed with the concomitant development of hypertension in SHR-SP. UCP2 mRNA levels in the epididymal fat of SHR-SP at 15 weeks were similar to that of WKY rats.

CONCLUSIONS

Altered gene expression of UCP2 and UCP3 might be related to some pathophysiological aspects in hypertension and glucose metabolism in SHR-SP.

Expression of multidrug resistance-associated protein (MRP) in human gliomas

Drug resistance is a major clinical problem in the chemotherapy of human gliomas. The multidrug resistance-associated protein (MRP), a membrane transporter related to non-P-glycoprotein multidrug resistance, is overexpressed in some drug-selected cancer cell lines. To investigate whether MRP is involved in the intrinsic drug resistance of human gliomas, surgical specimens of 20 gliomas (11 glioblastomas, 6 anaplastic astrocytomas, and 3 astrocytomas), 3 normal brain specimens, and 4 glioma cell lines (U87MG, U251MG, U373MG, and T98G) were analyzed. The expression of MRP was studied by RT-PCR and immunohistochemistry in the surgical specimens. The MRP expression levels in the cell lines were assessed by the quantitative RT-PCR and Western blot analyses. Sensitivity to adriamycin (ADM), etoposide (VP-16), cisplatin (CDDP), and 1-(4-amino-2-methyl-5-pyrimidinyl) methyl-3-(2-chloroethyl)-3-nitrosourea (ACNU), were determined by MTT assay, and antisense treatment was evaluated in the cell lines. The expression of MRP was detected in 9 of 11 glioblastomas and 3 of 6 anaplastic astrocytomas. The quantitative analyses of the cell lines revealed that the MRP mRNA and protein levels were increased 4.5-fold in the T98G cells as compared to U87MG. T98G cells showed the highest resistance to all drugs. Western blot analysis revealed that treatment with the antisense oligonucleotide reduced the level of MRP expression to 25% of the sense oligonucleotide treatment in T98G cells. The sensitivity to ADM, VP-16 and CDDP was significantly increased in the antisense-treated cells as compared with the sense-treated cells. These results suggest that the MRP expression may be related to the intrinsic multidrug resistance in human gliomas.