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Biomedical subjects

S Kida

Publications and source records attributed to S Kida.

At least 19 recordsLinked to original sources
PubMed2002

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.

Adult↗
PubMed2001

Tocopherol-associated protein is a ligand-dependent transcriptional activator.

Vitamin E is a term that encompasses a group of potent, lipid-soluble, chain-breaking antioxidants. Structural analysis reveals that molecules having vitamin E activity include four isomers (alpha, beta, gamma, and delta) of both tocopherols and tocotrienols. Alpha-tocopherol has been shown to have the highest biological vitamin E activity in mammalian tissues based on fetal resorption assays, and it reverses vitamin E deficiency symptoms. Although the molecular functions fulfilled specifically by alpha-tocopherol have yet to be fully described, it is unlikely that they are limited to general antioxidant functions. Here we show the functional characterization of alpha-tocopherol associated protein, TAP, which displays significant sequence similarity to the alpha-tocopherol transfer protein. Ligand competition analysis showed that recombinant TAP binds to alpha-tocopherol but not to other isomers of tocopherols. Using GFP fusion protein expression system, we observed that TAP translocates from cytosol to nuclei in alpha-tocopherol-dependent fashion. Transient transfection experiment showed that TAP activates transcription of the reporter gene in alpha-tocopherol-dependent manner. These results suggest that the biological function of alpha-tocopherol is not only as an antioxidant but also as a transcriptional regulator of gene expression via association with a transcription factor TAP.

Amino Acid Sequence↗
PubMed2001

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.

Adult↗
PubMed2001

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.

Brain↗
PubMed2001

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.

Adolescent↗
PubMed2000

Cerebellar hemorrhage after coil embolization for a ruptured vertebral dissecting aneurysm.

BACKGROUND: We present a case of ruptured vertebral dissecting aneurysm that exhibited cerebellar hemorrhage after successful embolization of the vertebral artery including the dissected site. CASE PRESENTATION: A 59-year-old man suffered a sudden onset of severe occipital headache when he looked up. Computed tomography demonstrated subarachnoid hemorrhage. Angiography revealed a right vertebral dissecting aneurysm distal to the posterior inferior cerebellar artery. Endovascular embolization of the aneurysm was performed with preservation of the posterior inferior cerebellar artery. The next day, the patient suffered a cerebellar hemorrhage in the vermis. The intracranial pressure was controlled by external ventricular drainage. The patient was discharged with mild cerebellar ataxia and bilateral abducens nerve palsy. CONCLUSION: In a case of vertebral dissecting aneurysm distal to the posterior inferior cerebellar artery, blood circulation in the vertebral arterial system may change after embolization of the aneurysm. In our case, the preserved posterior inferior cerebellar artery might have been hemodynamically stressed postoperatively, resulting in cerebellar hemorrhage. Therefore, strict control of blood pressure is essential in the acute stage after occlusion of the aneurysm.

Aneurysm, Ruptured↗
PubMed2000

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.

Adult↗
PubMed1999

Cervical lymph nodes play the role of regional lymph nodes in brain tumour immunity in rats.

Recent physiological and anatomical studies have demonstrated that a major fraction of brain interstitial and cerebrospinal fluid drains into cervical lymph nodes (CLN) in a number of experimental animals. To investigate the role of CLN in brain tumour immunity, temporal profiles of MHC class II molecule expression and T lymphocyte subsets in brain tumours, CLN and other lymphoid tissues were analysed by immunocytochemistry. A total of 64 Wistar rats weighing 250 g were used. Two weeks after the transplantation of C6 glioma cells (10(6) cells/1 microl) into a rat brain, expression of MHC class II molecules was induced in the brain and all systemic lymphoid tissues examined. However, the subsequent appearance of CD4 or CD8 positive cells was strictly confined to CLN, and coincided with the infiltration of such cells into the brain tumour 2 weeks after transplantation. In the group of animals in which cervical lymphadenectomy was followed by intracerebral transplantation of C6 glioma cells, infiltration of CD4 or CD8 positive cells into the brain tumour was delayed until 3 weeks after the transplantation, and the production of such cells was by the spleen. These results suggest that CLN act as regional lymph nodes in brain tumour immunity.

Animals↗
PubMed1999

Isolated histiocytosis X of the pituitary stalk.

A case of histiocytosis X granuloma localized in the pituitary stalk is reported. Coronal and sagittal magnetic resonance imaging views were useful to determine the precise size and location of the mass lesion. The diagnosis was established immunohistochemically and the patient was treated with low-dose irradiation therapy. After irradiation, the patient improved well without endocrine replacement treatment. The pituitary stalk recovered its normal size with no evidence of recurrence on MRI at 7-year follow-up. We emphasize the importance of MRI before initiating therapy to evaluate the pituitary mass lesion and the effectiveness of low-dose irradiation for isolated histiocytosis X.

Adult↗
PubMed1998

Middle cerebral artery occlusion in the rat causes a biphasic production of immunoreactive interleukin-1beta in the cerebral cortex.

Interleukin-1beta (IL-1beta) has been implicated in the sequence of events leading to neuronal cell death. We have used an ultrasensitive, highly specific immunometric assay for rat IL-1beta to determine the pattern of protein expression in the rat cerebral cortex following middle cerebral artery occlusion. In the ipsilateral cerebral cortex there was a biphasic pattern of production with a rapid early phase of IL-1beta expression followed by a delayed phase at 4 h which was sustained for up to 72 h. There was a similar but smaller expression of IL-1beta in the contralateral cortex. Sham operated animals showed no IL-1beta expression. These results provide further evidence to show that IL-1beta is expressed in the rat cerebral cortex following cerebral ischaemia.

Animals↗
PubMed1998

CREB and memory.

The cAMP responsive element binding protein (CREB) is a nuclear protein that modulates the transcription of genes with cAMP responsive elements in their promoters. Increases in the concentration of either calcium or cAMP can trigger the phosphorylation and activation of CREB. This transcription factor is a component of intracellular signaling events that regulate a wide range of biological functions, from spermatogenesis to circadian rhythms and memory. Here we review the key features of CREB-dependent transcription, as well as the involvement of CREB in memory formation. Evidence from Aplysia, Drosophila, mice, and rats shows that CREB-dependent transcription is required for the cellular events underlying long-term but not short-term memory. While the work in Aplysia and Drosophila only involved CREB function in very simple forms of conditioning, genetic and pharmacological studies in mice and rats demonstrate that CREB is required for a variety of complex forms of memory, including spatial and social learning, thus indicating that CREB may be a universal modulator of processes required for memory formation.

Animals↗
PubMed1997

Restricted expression of a member of the transcription elongation factor S-II family in testicular germ cells during and after meiosis.

Whether expression of transcription elongation factors is regulated during development has not been investigated, though genes encoding elongation factor S-II are transcribed in a tissue-specific manner. We investigated the expression profile of tissue-specific S-II during development using an isolated cDNA, termed mouse S-II-T1, whose transcripts are detected almost exclusively in testis. Three experiments were performed with various types of germ and somatic cells in testis to determine in which cells S-II-T1 is expressed. (1) Expression of S-II-T1 is markedly reduced in the testes of adult WBB6F1-W/Wv mutant mice which lack testicular germ cells, indicating its expression is specific to testicular germ cells. (2) The onset of mouse S-II-T1 mRNA appearance in testis is seen about 10-14 days after birth, which is consistent with the start of meiotic events, suggesting that S-II-T1 is not transcribed in premeiotic and early meiotic cells such as spermatogonia, leptotene spermatocytes, or zygotene spermatocytes. (3) Mouse S-II-T1 transcripts accumulate in meiotic pachytene spermatocytes and are detected in postmeiotic haploid cells such as round and elongated spermatids during spermatogenesis, as shown by fractionation of testicular germ cells at four different stages. These results indicate that expression of mouse S-II-T1 is restricted to testicular germ cells during and after meiosis in the course of spermatogenesis. This is the first report that expression of a transcription elongation factor in particular cells is regulated in a stage-specific manner in the course of development.

Amino Acid Sequence↗
PubMed1997

Membranous ultrastructure of human arachnoid cells.

The ultrastructure of arachnoid cell membranes was investigated by conventional transmission EM and by freeze-fracture techniques in human arachnoid granulations. Arachnoid cells showed widespread membrane specialization in the granulations including the formation of desmosomes, gap junctions, tight junctions, intermediate junctions, hemidesmosome-like structures, and micropinocytotic vesicles. However, the extent of the specialization varied from portion to portion; this was clearly shown on freeze-fracture replicas. Numerous extracellular cisterns were separated by cytoplasmic bodies or slender processes, joined by these junctional complexes. Uncoated and coated vesicles were abundant along the surface of extracellular cisterns representing the pathway of CSF. Complexes of branching tight junctions were comprised of 1-50 particle strands, which formed elaborate meshworks accompanied by numerous gap junctions and desmosomes. Micropinocytotic vesicles were often concentrated in the arachnoid cell cluster up to 40 per microm2, which is equivalent to the concentration in brain capillary endothelial cells. The results of this study clearly suggest that arachnoid cells in arachnoid granulations are not only tightly adherent to form a firm structure for the passage of CSF, but that the arachnoid cells lining the CSF pathway show intense cell-cell communication and pinocytotic activity. This high transcellular activity probably reflects active transports or secretion of certain molecules by arachnoid cells.

Adolescent↗