Biomedical subjects

Masahiko Watanabe

Publications and source records attributed to Masahiko Watanabe.

At least 37 records · Page 2Linked to original sources

PubMed2006

Expression and distribution of JNK/SAPK-associated scaffold protein JSAP1 in developing and adult mouse brain.

The c-Jun N-terminal kinase (JNK) is one of the three major mitogen-activated protein kinases (MAPKs) playing key roles in various cellular processes in response to both extracellular and intracellular stimuli. JNK/SAPK-associated protein 1 (JSAP1 also referred to as JIP3) is a JNK-associated scaffold that controls the specificity and efficiency of JNK signaling cascades. Here we studied its expression in mouse brains. JSAP1 mRNA was expressed in developing and adult brains, showing spatial patterns similar to JNK1-3 mRNAs. In embryos, JSAP1 immunolabeling was intense for progenitor cells in the ventricular zone throughout the brain and in the external granular layer of the cerebellum, and for neurons and glial cells differentiating in the mantle zone. In adults, JSAP1 was distributed in various neurons and Bergmann glia, with higher levels in striatal cholinergic interneurons, telencephalic parvalbumin-positive interneurons and cerebellar Purkinje cells. In these neurons, JSAP1 was observed as tiny particulate staining in spines, dendrites, perikarya and axons, where it was often associated with the smooth endoplasmic reticulum (sER) and cell membrane. Immunoblots revealed enriched distribution in the microsomal fraction and cytosolic fraction. Therefore, the characteristic cellular expression and subcellular distribution of JSAP1 might be beneficial for cells to efficiently link external stimuli to the JNK MAPK pathway and other intracellular machineries.

Adaptor Proteins, Signal Transducing↗

PubMed2006

Phenotyping of sensory and sympathetic ganglion neurons of a galanin-overexpressing mouse--possible implications for pain processing.

The distribution of galanin was studied in the lumbar 5 dorsal root ganglia (DRGs) and spinal cord, superior cervical ganglia (SCGs), and skin of transgenic mice overexpressing galanin under the dopamine beta-hydroxylase (DBH) promoter (GalOE-DBH mice) and in wild type (WT) mice. The DRGs and spinal cord were analysed before and after a unilateral, complete transection (axotomy) of the sciatic nerve and after dorsal rhizotomy. Both galanin protein and transcript were studied by, respectively, immunohistochemistry and in situ hybridization. Increased galanin expression was observed in several small, medium-sized and large DRG neuron profiles (NPs) in the naïve transgenic mouse, frequently in neurons lacking calcitonin gene-related peptide (CGRP) and isolectin B4-binding. This lack of coexistence was particularly evident in the medium-sized/large NPs. In the dorsal horn of the spinal cord, no differences were detected between GalOE-DBH and WT mice, both displaying a strong galanin-positive neuropil in the superficial laminae of the dorsal horn, but the transgenic mice showed a more abundant galanin-positive innervation of the ventral horn. A 12-day dorsal rhizotomy, surprisingly, failed to alter the galanin staining patterns in the dorsal (and ventral) dorsal horn. Unilateral axotomy induced upregulation of galanin in DRG NPs of all sizes in both types of mouse. In the hindpaw skin, a profuse galanin-positive fiber plexus was observed in sweat glands and around blood vessels of the transgenic mice, being much more restricted in WT mice. Finally, GalOE mice exhibited a strong galanin-like immunoreactivity in most SCG NPs. The overexpression of the peptide in DRGs and SCGs was paralleled by increased mRNA levels. The present results show that overexpression of galanin under the control of the DBH promoter does not only occur, as expected in these mice, in noradrenline/adrenaline neurons but also in DRG neurons, particularly in large and medium-sized NPs. To what extent and how this overexpression pattern is related to the previously shown elevated pain threshold under normal and lesion conditions is discussed [Grass, S., Crawley, J.N., Xu, X.J., Wiesenfeld-Hallin, Z., 2003a. Reduced spinal cord sensitization to C-fibre stimulation in mice over-expressing galanin. Eur. J. Neurosci. 17, 1829-1832; Hygge-Blakeman, K., Brumovsky, P., Hao, J.X., Xu, X.J., Hökfelt, T., Crawley, J.N., Wiesenfeld-Hallin, Z., 2004. Galanin over-expression decreases the development of neuropathic pain-like behaviour in mice after partial sciatic nerve injury. Brain Res. 1025, 152-158].

Animals↗

PubMed2006

The CB1 cannabinoid receptor is the major cannabinoid receptor at excitatory presynaptic sites in the hippocampus and cerebellum.

Endocannabinoids work as retrograde messengers and contribute to short-term and long-term modulation of synaptic transmission via presynaptic cannabinoid receptors. It is generally accepted that the CB1 cannabinoid receptor (CB1) mediates the effects of endocannabinoid in inhibitory synapses. For excitatory synapses, however, contributions of CB1, "CB3," and some other unidentified receptors have been suggested. In the present study we used electrophysiological and immunohistochemical techniques and examined the type(s) of cannabinoid receptor functioning at hippocampal and cerebellar excitatory synapses. Our electrophysiological data clearly demonstrate the predominant contribution of CB1. At hippocampal excitatory synapses on pyramidal neurons the cannabinoid-induced synaptic suppression was reversed by a CB1-specific antagonist, N-(piperidin-1-yl)-5-(4-iodophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide (AM251), and was absent in CB1 knock-out mice. At climbing fiber (CF) and parallel fiber (PF) synapses on cerebellar Purkinje cells the cannabinoid-dependent suppression was absent in CB1 knock-out mice. The presence of CB1 at presynaptic terminals was confirmed by immunohistochemical experiments with specific antibodies against CB1. In immunoelectron microscopy the densities of CB1-positive signals in hippocampal excitatory terminals and cerebellar PF terminals were much lower than in inhibitory terminals but were clearly higher than the background. Along the long axis of PFs, the CB1 was localized at a much higher density on the perisynaptic membrane than on the extrasynaptic and synaptic regions. In contrast, CB1 density was low in CF terminals and was not significantly higher than the background. Despite the discrepancy between the electrophysiological and morphological data for CB1 expression on CFs, these results collectively indicate that CB1 is responsible for cannabinoid-dependent suppression of excitatory transmission in the hippocampus and cerebellum.

6-Cyano-7-nitroquinoxaline-2,3-dione↗

PubMed2006

Improved methods for ultracryotomy of CNS tissue for ultrastructural and immunogold analyses.

We examined each step of the protocol for ultracryotomy for central nervous system tissue in order to define and overcome some of the methodological difficulties. The following three steps emerged as critical for the method's success: (1) pretreatment of grids to render them hydrophilic immediately before use; (2) careful collection of ultrathin cryosections during ultracryotomy; (3) removal of the appropriate amount of excess poly(vinyl alcohol)-uranyl acetate (PVA-UA) prior to drying after staining with PVA-UA. By taking account of the three critical steps described above, we succeeded in obtaining ultrathin cryosections, including serial sections, with excellent preservation of ultrastructure, as well as semithin cryosections which are useful for evaluating the quality of the samples and for selecting areas of interest for ultrastructural analysis. Cytoplasmic organelles in neurons and glial cells, and the fine structure of synapses and myelinated fibers were well preserved. The localization of gold particles after immunostaining for astrocytic glutamate transporter (GLAST), metabotropic glutamate receptor 1 (mGluR1) and neurofilament protein was consistent with previous reports and ultrastructure was well-preserved in all cases. These findings should be helpful to researchers wishing to carry out ultrastructural and immunogold analyses of cryosections of nervous tissue.

Animals↗

PubMed2006

Laparoscopic Heller myotomy with Toupet fundoplication for achalasia straightens the esophagus and relieves dysphagia.

BACKGROUND: A standard procedure for the treatment of achalasia remains to be established. We assessed the usefulness of a laparoscopic Heller myotomy with a Toupet fundoplication (LHT). METHODS: LHT was performed in 30 patients (12 men, 18 women; mean age, 41.8 y) who had esophageal achalasia with severe dysphagia. Caution was exercised when the esophagus was pulled downward and straightened. Symptoms and esophageal function were evaluated before and after surgery. RESULTS: The esophagus was straightened surgically in 22 (88%) of 25 patients with esophageal curvature on preoperative esophagography. The dysphagia score decreased to 1.7 +/- 1.2 (mean +/- SD) points from a preoperative value of 10. The lower esophageal sphincter pressure decreased significantly. Two patients (7%) had esophageal diverticula as postoperative sequelae. Pathologic acid reflex was noted in 3 patients (12%). CONCLUSIONS: LHT is a useful procedure for straightening the esophagus, reducing lower esophageal sphincter pressure, and relieving dysphagia in patients with achalasia.

Adult↗

PubMed2006

Interaction between stromal fibroblasts and colorectal cancer cells in the expression of vascular endothelial growth factor.

BACKGROUND: Vascular endothelial growth factor (VEGF), a potent angiogenic factor, has been implicated in metastasis of colorectal cancer (CRC). The present study aimed to clarify whether cancer-stromal interaction induces the production of VEGF. MATERIALS AND METHODS: Human colonic fibroblasts (CCD-18Co) and CRC (SW480, SW620) cells were analyzed in this study. The cell cycle of colonic fibroblasts during co-culture was analyzed by flow cytometry. VEGF and TGF-beta1 released into the conditioned media in co-culture models were measured. Northern blot with human specific VEGF probe was performed to identify the expression of VEGF in this model. RESULTS: Co-culture of colonic fibroblasts with CRC cells increased the viability of fibroblasts during co-culture. Cell cycle analysis revealed that most of the fibroblasts co-cultured with CRC cells were arrested at G1 phase and few cells were in sub-G1 phase that indicates apoptosis. Although VEGF protein was detected in the culture media of all of the monocultures, co-cultivation of CRC with fibroblasts resulted in synergistic increase of VEGF production compared with monocultures. However TGF-beta1 protein was not detected in any conditioned medium. VEGF mRNA was detected in both CRC and fibroblasts. Under co-culture condition, an abundance of VEGF mRNA expression was noted in fibroblasts relative to CRC cells. CONCLUSIONS: The present study suggests that CRC manipulates the host stroma to suppress apoptosis and up-regulate VEGF production.

Apoptosis↗

PubMed2006

Biological effects of anhydrobiosis in an African chironomid, Polypedilum vanderplanki on radiation tolerance.

PURPOSE: Anhydrobiotic organisms are known to have an extremely high tolerance against a range of stresses. However, the functional role of anhydrobiosis in radiation tolerance is poorly understood, especially in development following irradiation. The present study aims to evaluate effects of anhydrobiosis on radiation tolerance in an anhydrobiotic insect, Polypedilum vanderplanki. MATERIALS AND METHODS: Larval survival (48 h), anhydrobiotic ability, metamorphosis and reproduction after exposure to 1-9000 Gy of gamma-rays at the larval stage were compared between anhydrobiotic (dry) and normal (wet) phases. RESULTS: Wet larvae were killed in a dose-dependent manner at doses higher than 2000 Gy, and all died within 8 h after 4000 Gy exposure. In contrast, dry larvae survived even 5000 Gy, and some of them still tolerated 7000 Gy and were alive at 48 h after rehydration. Moreover, greater radiotolerance of dry larva, compared to wet ones, was demonstrated in terms of metamorphoses. However, anhydrobiosis did not protect against radiation damage in terms of producing viable offspring. CONCLUSION: These results indicate that anhydrobiosis enhances radiotolerance, resulting in increases of successful metamorphoses.

Animals↗

PubMed2006

Radiation tolerance in the tardigrade Milnesium tardigradum.

PURPOSE: Tardigrades are known to survive high doses of ionizing radiation. However, there have been no reports about radiation effects in tardigrades under culture conditions. In this study, we investigated tolerance of the tardigrade, Milnesium tardigradum, against gamma-rays and heavy ions by determining short-term or long-term survival, and reproductive ability after irradiation. MATERIALS AND METHODS: Hydrated and anhydrobiotic animals were exposed to gamma-rays (1000 - 7000 Gy) or heavy ions (1000 - 8000 Gy) to evaluate short-term survival at 2, 24 and 48 h post-irradiation. Long-term survival and reproduction were observed up to 31 days after irradiation with gamma-rays (1000 - 4000 Gy). RESULTS: At 48 h after irradiation, median lethal doses were 5000 Gy (gamma-rays) and 6200 Gy (heavy ions) in hydrated animals, and 4400 Gy (gamma-rays) and 5200 Gy (heavy ions) in anhydrobiotic ones. Gamma-irradiation shortened average life span in a dose-dependent manner both in hydrated and anhydrobiotic groups. No irradiated animals laid eggs with one exception in which a hydrated animal irradiated with 2000 Gy of gamma-rays laid 3 eggs, and those eggs failed to hatch, whereas eggs produced by non-irradiated animals hatched successfully. CONCLUSION: M. tardigradum survives high doses of ionizing radiation in both hydrated and anhydrobiotic states, but irradiation with >1000 Gy makes them sterile.

Animals↗

PubMed2006

Estimation of radiation tolerance to high LET heavy ions in an anhydrobiotic insect, Polypedilum vanderplanki.

PURPOSE: Anhydrobiotic larvae of Polypedilum vanderplanki are known to show an extremely high tolerance against a range of stresses. We have recently reported that this insect withstands exposure to high doses of gamma-rays (linear energy transfer [LET] 0.2 keV/microm). However, its tolerance against high LET radiation remains unknown. The aim of this study is to characterize the tolerance to high-LET radiations of P. vanderplanki. MATERIALS AND METHODS: Larval survival and subsequent metamorphoses were compared between anhydrobiotic (dry) and non-anhydrobiotic (wet) samples after exposure to 1 - 7000 Gy of three types of heavy ions delivered from the azimuthally varying field (AVF) cyclotron with LET values ranging from 16.2 - 321 keV/microm. The tolerance against 4He ions was also compared among three chironomid species. RESULTS: At all LET values measured, dry larvae consistently showed greater radiation tolerance than hydrated larvae, perhaps due to the presence of high concentrations of the disaccharide trehalose in anhydrobiotic animals, and the radiation-induced damage became evident at lower doses as development progressed. Relative biological effectiveness (RBE) values based on the median inhibitory doses reached a maximum at 116 keV/microm (12C), and the maximum RBE clearly increased as development progressed. Lower D0 (dose to reduce survival from relative value 1.00 - 0.37 on the exponential part of the survival curve), and higher Dq (quasi-threshold dose) were found in individuals exposed to 4He ions, compared to gamma-rays, and in P. vanderplanki larvae compared to non-anhydrobiotic chironomids. CONCLUSION: Anhydrobiosis potentiates radiation tolerance in terms of larval survival, pupation and adult emergence of P. vanderplanki exposed to high-LET radiations as well as to low-LET radiation. P. vanderplanki larvae might have more efficient DNA damage repair after radiation than other chironomid species.

Animals↗

PubMed2006

Intramedullary spinal cord metastasis: a clinical and imaging study of seven patients.

OBJECTIVES: Intramedullary spinal cord metastasis (ISCM) is a rare complication of cancer. This complication has been studied by magnetic resonance imaging (MRI) more frequently in the clinical context to improve the survival time of cancer patients. However, the number of the reports of its clinical management or radiographic findings is small. To investigate the clinical and imaging characteristics of ISCM, seven cases of ISCM of a nonneurogenic origin were examined retrospectively. METHOD: Data regarding the site of the primary neoplasm, location of other metastases, initial symptoms, interval from the original diagnosis of cancer to the onset of neurologic symptoms, time course from initial symptoms to urinary retention, MRI data, and outcome after radiologic or surgical intervention were investigated. RESULTS: Five patients had lung cancer metastases, and one each had breast or uterine cancer metastases. The progression of neurologic deficit was rapid, and the average period between the occurrence of initial symptoms and urinary retention was 25 days. The averaged survival period from the diagnosis of ISCM was 5 months in three patients. (One patient is alive, and the data could not be obtained in another three patients.) MRI characteristics were useful for diagnosis, including large high signal intensity areas on T2-weighted images and strong ring or inhomogeneous enhancement on gadopentetate dimeglumine-enhanced T1-weighted images. Surgery was performed on two patients, but total removal could not be achieved. Radiotherapy was effective in treating neurologic deficit in five patients. CONCLUSION: Surgical treatment is seldom indicated for ISCM, and radiotherapy is recommended as soon as possible after a diagnosis is made from MRI.

Aged↗

PubMed2006

Correlation of enhanced cell turnover with prognosis of gastrointestinal stromal tumors of the stomach: relevance of cellularity and p27kip1.

The aim of the present study was to determine whether expression of molecules associated with cell cycle regulation and apoptosis might reflect tumor grade and patients' prognosis of gastrointestinal stromal tumor (GIST). Forty-nine cases of gastric GIST were divided into three grades; low, intermediate, and high risk. Ki-67, cyclin A, cyclin D1, cyclin E, p16(Ink4), p21(Waf1), p27(Kip1), cyclin-dependent kinase (cdk)2, cdk4 and single-strand DNA (ssDNA) were immunohistochemically stained and assessed. Ki-67, ssDNA, cyclin A and cdk2 had higher labeling indices (LI) in high-risk than in low-risk cases. Cyclin E expression was greater in the intermediate- than in the low-risk grade. On Kaplan-Meier analysis, tumor size, necrosis, cellularity, Ki-67, ssDNA, and cyclin A LI were significantly correlated with disease-free survival. Necrosis, cellularity, and Ki-67 LI were significant as prognostic factors on univariate, and Ki-67 LI on multivariate Cox hazard tests. Within the high-risk grade, high cellularity and low p27(Kip1) subgroups had the worst prognosis. The histological grade is related to cell turnover, assessed in terms of Ki-67, ssDNA, cyclin A, cyclin E, and cdk2 levels. Ki-67, ssDNA, and cyclin A are useful for prediction of prognosis, with cellularity and p27(Kip1) expression as further prognostic factors in high-risk cases.

Aged↗

PubMed2006

Diacylglycerol kinase zeta is involved in the process of cerebral infarction.

Diacylglycerol kinase (DGK) is an enzyme that phosphorylates a second messenger diacylglycerol (DG) and is involved in a variety of pathophysiological cellular responses. We have previously reported that DGKzeta may be involved in the selective vulnerability of hippocampal CA1 neurons in transient forebrain ischemia. In this study we aimed to further elucidate functional implications of DGK isozymes in the cerebral cortex suffering from infarction using a focal ischemic model. In the early phase of 90 min of middle cerebral artery occlusion, DGKzeta-immunoreactivity is reduced rapidly in the nucleus of cortical neurons in the ischemic core, while DGKiota and other neuronal proteins such as MAP-2 and NeuN remain intact. This suggests that rapid disappearance of DGKzeta in ischemic neurons is a quite early event precedent to neuronal degeneration in response to ischemia. Furthermore, in the late inflammatory phase of infarction DGKzeta-immunoreactivity is detected in non-neuronal cells including factor VIII-positive endothelial cells and ED-1-positive phagocytic cells. The present study suggests that DGKzeta may play roles in various processes of ischemic brain damage including neuronal death and non-neuronal inflammatory response.

Animals↗

PubMed2006

Distinct expression of Cbln family mRNAs in developing and adult mouse brains.

Cbln1 belongs to the C1q and tumour necrosis factor superfamily, and plays crucial roles as a cerebellar granule cell-derived transneuronal regulator for synapse integrity and plasticity in Purkinje cells. Although Cbln2-Cbln4 are also expressed in the brain and could form heteromeric complexes with Cbln1, their precise expressions remain unclear. Here, we investigated gene expression of the Cbln family in developing and adult C57BL mouse brains by reverse transcriptase-polymerase chain reaction (RT-PCR), Northern blot, and high-resolution in situ hybridization (ISH) analyses. In the adult brain, spatial patterns of mRNA expression were highly differential depending on Cbln subtypes. Notably, particularly high levels of Cbln mRNAs were expressed in some nuclei and neurons, whereas their postsynaptic targets often lacked or were low for any Cbln mRNAs, as seen for cerebellar granule cells/Purkinje cells, entorhinal cortex/hippocampus, intralaminar group of thalamic nuclei/caudate-putamen, and dorsal nucleus of the lateral lemniscus/central nucleus of the inferior colliculus. In the developing brain, Cbln1, 2, and 4 mRNAs appeared as early as embryonic day 10-13, and exhibited transient up-regulation during the late embryonic and neonatal periods. For example, Cbln2 mRNA was expressed in the cortical plate of the developing neocortex, displaying a high rostromedial to low caudolateral gradient. In contrast, Cbln3 mRNA was selective to cerebellar granule cells throughout development, and its onset was as late as postnatal day 7-10. These results will provide a molecular-anatomical basis for future studies that characterize roles played by the Cbln family.

Aging↗

PubMed2006

Abundant distribution of TARP gamma-8 in synaptic and extrasynaptic surface of hippocampal neurons and its major role in AMPA receptor expression on spines and dendrites.

Transmembrane alpha-amino-3-hydroxyl-5-isoxazolepropionate (AMPA) receptor regulatory proteins (TARPs) play pivotal roles in AMPA receptor trafficking and gating. Here we examined cellular and subcellular distribution of TARP gamma-8 in the mouse brain. Immunoblot and immunofluorescence revealed the highest concentration of gamma-8 in the hippocampus. Immunogold electron microscopy demonstrated dense distribution of gamma-8 on the synaptic and extrasynaptic surface of hippocampal neurons with very low intracellular labeling. Of the neuronal surface, gamma-8 was distributed at the highest level on asymmetrical synapses of pyramidal cells and interneurons, whereas their symmetrical synapses selectively lacked immunogold labeling. Then, the role of gamma-8 in AMPA receptor expression was pursued in the hippocampus using mutant mice defective in the gamma-8 gene. In the mutant cornu ammonis (CA)1 region, synaptic and extrasynaptic AMPA receptors on dendrites and spines were severely reduced to 35-37% of control levels, whereas reduction was mild for extrasynaptic receptors on somata (74%) and no significant decrease was seen for intracellular receptors within spines. In the mutant CA3 region, synaptic AMPA receptors were reduced mildly at asymmetrical synapses in the stratum radiatum (67% of control level), and showed no significant decrease at mossy fiber-CA3 synapses. Therefore, gamma-8 is abundantly distributed on hippocampal excitatory synapses and extrasynaptic membranes, and plays an important role in increasing the number of synaptic and extrasynaptic AMPA receptors on dendrites and spines, particularly, in the CA1 region. Variable degrees of reduction further suggest that other TARPs may also mediate this function at different potencies depending on hippocampal subregions, input sources and neuronal compartments.

Animals↗

PubMed2006

Involvement of the ATR- and ATM-dependent checkpoint responses in cell cycle arrest evoked by pierisin-1.

Pierisin-1 identified from the cabbage butterfly, Pieris rapae, is a novel mono-ADP-ribosylating toxin that transfers the ADP-ribose moiety of NAD at N(2) of dG in DNA. Resulting mono-ADP-ribosylated DNA adducts cause mutations and the induction of apoptosis. However, little is known about checkpoint responses elicited in mammalian cells by the formation of such bulky DNA adducts. In the present study, it was shown that DNA polymerases were blocked at the specific site of mono-ADP-ribosylated dG, which might lead to the replication stress. Pierisin-1 treatment of HeLa cells was found to induce an intra-S-phase arrest through both ataxia telangiectasia mutated (ATM) and Rad3-related (ATR) and ATM pathways, and ATR pathway also contributes to a G(2)-M-phase delay. In the colony survival assays, Rad17(-/-) DT40 cells showed greater sensitivity to pierisin-1-induced cytotoxicity than wild-type and ATM(-/-) DT40 cells, possibly due to defects of checkpoint responses, such as the Chk1 activation. Furthermore, apoptotic 50-kb DNA fragmentation was observed in the HeLa cells, which was well correlated with occurrence of phosphorylation of Chk2. These results thus suggest that pierisin-1 treatment primarily activates ATR pathway and eventually activates ATM pathway as a result of the induction of apoptosis. From these findings, it is suggested that mono-ADP-ribosylation of DNA causes a specific type of fork blockage that induces checkpoint activation and signaling.

ADP Ribose Transferases↗

PubMed2006

Laparoscopic low anterior resection for rectal cancer.

More so than with other types of colon cancer, rectal cancer is associated with a range of laparoscopic surgical techniques. Treatment of cancer of the lower rectum requires favorable operative fields, minimal contact with the tumor during dissection, and delicate surgical procedures to avoid nerve damage. Such surgery thus requires immobilizing the trunk so the patient can be repositioned as needed, placing ports at appropriate locations, as well as careful handling of surgical equipment. To minimize the risk of disseminating cancer cells during the procedure, the surgery should be restricted to patients with early-stage cancer. The most difficult surgical procedure is resection of the lower rectum. While safe resection of the intestinal tract was difficult using previously available surgical equipment, newly developed equipment makes today's resections much safer and easier. Indications for surgical intervention should be broadened carefully, based on a deeper understanding of the surgical anatomy within the pelvis and on various relevant oncological and technical factors.

Colorectal Surgery↗

PubMed2005

Maintenance of presynaptic function by AMPA receptor-mediated excitatory postsynaptic activity in adult brain.

Activity-dependent synaptic modification occurs in both developing and mature animals. For reliable information transfer and storage, however, once established, synapses must be maintained stably. We investigated how chronic blockade of neuronal activity or alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-type glutamate receptors affects excitatory climbing fiber (CF) to Purkinje cell (PC) synapses in adult mouse cerebellum. Both treatments caused reduced glutamate concentration transient at the synaptic cleft, decreased frequency of quantal excitatory postsynaptic current, and diminished CF innervation of PC shaft dendrites but no change in CF's release probability. These results indicate that, in the mature cerebellum, AMPA receptor-mediated excitatory postsynaptic activity maintains CF's functional glutamate-release sites and its innervation of PC shaft dendrites.

Anesthetics, Local↗

PubMed2005

Impaired cerebellar functions in mutant mice lacking DNER.

DNER is a transmembrane protein carrying extracellular EGF repeats and is strongly expressed in Purkinje cells (PCs) in the cerebellum. Current study indicated that DNER functions as a new Notch ligand and mediates the functional communication via cell-cell interaction. By producing and analyzing knockout mice lacking DNER, we demonstrate its essential roles in functional and morphological maturation of the cerebellum. The knockout mice exhibited motor discoordination in the fixed bar and rota-rod tests. The cerebellum from the knockout mice showed significant retardation in morphogenesis and persistent abnormality in fissure organization. Histochemical and electrophysiological analyses detected that PCs retained multiple innervations from climbing fibers (CFs) in the mutant cerebellum. Synaptic transmission from parallel fibers (PFs) or CFs to PCs was apparently normal, while glutamate clearance at the PF-PC synapses was significantly impaired in the mutant mice. Moreover, the protein level of GLAST, the glutamate transporter predominantly expressed in Bergmann glia (BG), was reduced in the mutant cerebellum. Our results indicate that DNER takes part in stimulation of BG maturation via intercellular communication and is essential for precise cerebellar development.

Animals↗