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Mestres-Ventura P, Morguet A, de las Heras SGG. Multi-sensor arrays for online monitoring of cell dynamics in in vitro studies with choroid plexus epithelial cells. SENSORS 2012; 12:1383-97. [PMID: 22438715 PMCID: PMC3304117 DOI: 10.3390/s120201383] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Revised: 01/13/2012] [Accepted: 01/17/2012] [Indexed: 12/02/2022]
Abstract
Sensors and multi-sensor arrays are the basis of new technologies for the non-label monitoring of cell activity. In this paper we show that choroid plexus cells can be cultured on silicon chips and that sensors register in real time changes in their activity, constituting an interesting experimental paradigm for cell biology and medical research. To validate the signals recorded (metabolism = peri-cellular acidification, oxygen consumption = respiration; impedance = adhesion, cell shape and motility) we performed experiments with compounds that act in a well-known way on cells, influencing these parameters. Our in vitro model demonstrates the advantages of multi-sensor arrays in assessment and experimental characterization of dynamic cellular events—in this case in choroid plexus functions, however with applicability to other cell types as well.
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Affiliation(s)
- Pedro Mestres-Ventura
- Department of Anatomy and Cell Biology, Saarland University, University Hospital, Bldg. 61, 66421 Homburg, Saar, Germany; E-Mail:
- Department of Human Histology and Pathology, Faculty for Health Sciences, University Rey Juan Carlos I, Av. de Atenas s/n, E-28922 Alcorcón, Madrid, Spain; E-Mail:
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +34-91-488-8622; Fax: +34-91-488-8955
| | - Andrea Morguet
- Department of Anatomy and Cell Biology, Saarland University, University Hospital, Bldg. 61, 66421 Homburg, Saar, Germany; E-Mail:
| | - Soledad García Gómez de las Heras
- Department of Human Histology and Pathology, Faculty for Health Sciences, University Rey Juan Carlos I, Av. de Atenas s/n, E-28922 Alcorcón, Madrid, Spain; E-Mail:
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202
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CNS penetration of intrathecal-lumbar idursulfase in the monkey, dog and mouse: implications for neurological outcomes of lysosomal storage disorder. PLoS One 2012; 7:e30341. [PMID: 22279584 PMCID: PMC3261205 DOI: 10.1371/journal.pone.0030341] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2011] [Accepted: 12/14/2011] [Indexed: 02/03/2023] Open
Abstract
A major challenge for the treatment of many central nervous system (CNS) disorders is the lack of convenient and effective methods for delivering biological agents to the brain. Mucopolysaccharidosis II (Hunter syndrome) is a rare inherited lysosomal storage disorder resulting from a deficiency of iduronate-2-sulfatase (I2S). I2S is a large, highly glycosylated enzyme. Intravenous administration is not likely to be an effective therapy for disease-related neurological outcomes that require enzyme access to the brain cells, in particular neurons and oligodendrocytes. We demonstrate that intracerebroventricular and lumbar intrathecal administration of recombinant I2S in dogs and nonhuman primates resulted in widespread enzyme distribution in the brain parenchyma, including remarkable deposition in the lysosomes of both neurons and oligodendrocytes. Lumbar intrathecal administration also resulted in enzyme delivery to the spinal cord, whereas little enzyme was detected there after intraventricular administration. Mucopolysaccharidosis II model is available in mice. Lumbar administration of recombinant I2S to enzyme deficient animals reduced the storage of glycosaminoglycans in both superficial and deep brain tissues, with concurrent morphological improvements. The observed patterns of enzyme transport from cerebrospinal fluid to the CNS tissues and the resultant biological activity (a) warrant further investigation of intrathecal delivery of I2S via lumbar catheter as an experimental treatment for the neurological symptoms of Hunter syndrome and (b) may have broader implications for CNS treatment with biopharmaceuticals.
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203
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Kalani MYS, Filippidis AS, Rekate HL. Hydrocephalus and aquaporins: the role of aquaporin-1. ACTA NEUROCHIRURGICA. SUPPLEMENT 2012; 113:51-4. [PMID: 22116423 DOI: 10.1007/978-3-7091-0923-6_11] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
INTRODUCTION Aquaporins (AQPs) are membrane proteins that facilitate water and small solute movement in tissues. Hydrocephalus is a major central nervous system disorder associated with defective cerebrospinal fluid (CSF) turnover. Aquaporin-1 (AQP1) is a water channel located mainly at the choroid plexus epithelium and plays an active role in CSF production. The aim of this study is to review the pertinent literature concerning the role of aquaporin-1 in the pathophysiology of hydrocephalus. METHODS We performed a MEDLINE search using the terms aquaporin AND hydrocephalus. The results of the search were further refined to exclude studies not related to aquaporin-1. RESULTS Five studies were identified. Three of these studies utilized an animal model, while only two studies referred to a few human cases of hydrocephalus. Most of the studies indicate that there is a down-regulation of AQP1 expression in choroid plexus in models of hydrocephalus. A small series of human choroid plexus tumors showed that AQP1 expression is up-regulated. In cases of human choroid plexus tumors, there are indications that AQP1 may have alternative physiologic roles, but it is not clear whether this is associated with a specific type of hydrocephalus or the genetic burden of the tumor. CONCLUSION There has been a paucity of research on the link between aquaporins and hydrocephalus. Most studies have relied on animal models. An adaptive and protective role of AQP1 as a regulator of CSF production is proposed in the pathophysiology of hydrocephalus. Further research is needed to clarify if this association exists in humans.
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Affiliation(s)
- M Y S Kalani
- St. Joseph's Hospital and Medical Center, Phoenix, AZ, USA
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204
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Jurjević I, Maraković J, Chudy D, Markelić I, Klarica M, Froebe A, Orešković D. Dependence of cerebrospinal fluid pressure and volume on the changes in serum osmolarity in cats. ACTA NEUROCHIRURGICA. SUPPLEMENT 2012; 114:351-5. [PMID: 22327722 DOI: 10.1007/978-3-7091-0956-4_68] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
OBJECTIVES To study the effect of blood osmolarity on cerebrospinal fluid (CSF) volume and CSF pressure in cats. METHODS Three types of methods were used on anesthetized cats. The first, ventriculo-cisternal perfusion (12.96 μL/min) before and after i.v. application of 20% mannitol; the second, measuring the outflow of CSF by cisternal free drainage; and the third, measuring CSF pressure in the ventricles of an intact CSF system, with the second and third method being performed before and after the i.p. application of a hypo-osmolar substance (distilled water). RESULTS In the first group, the application of 20% mannitol led to a significantly reduced (p < 0.005) outflow volume (from 12.60 ± 0.29 to 0.94 ± 0.09 μL/min). In the second group, the outflow CSF volume significantly increased (p < 0.001) after the application of distilled water (from 18.8 ± 0.3 to 28.2 ± 0.7 μL/min). In the third group, after the application of distilled water, the CSF pressure also significantly increased (p < 0.05; from 8.3 ± 0.8 to 16.1 ± 0.14 cm H(2)O). CONCLUSION We conclude that changes in serum osmolarity change the CSF volume because of the osmotic gradient between the blood and all of the CSF compartments, and also that the change in CSF pressure is closely associated with changes in CSF volume.
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Affiliation(s)
- Ivana Jurjević
- Department of Pharmacology, University of Zagreb School of Medicine, Zagreb, Croatia
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205
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Lobas MA, Helsper L, Vernon CG, Schreiner D, Zhang Y, Holtzman MJ, Thedens DR, Weiner JA. Molecular heterogeneity in the choroid plexus epithelium: the 22-member γ-protocadherin family is differentially expressed, apically localized, and implicated in CSF regulation. J Neurochem 2011; 120:913-27. [PMID: 22092001 DOI: 10.1111/j.1471-4159.2011.07587.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The choroid plexus (CP) epithelium develops from the ependyma that lines the ventricular system, and plays a critical role in the development and function of the brain. In addition to being the primary site of CSF production, the CP maintains the blood-CSF barrier via apical tight junctions between epithelial cells. Here we show that the 22-member γ-protocadherin (γ-Pcdh) family of cell adhesion molecules, which we have implicated previously in synaptogenesis and neuronal survival, is highly expressed by both CP epithelial and ependymal cells, in which γ-Pcdh protein localization is, surprisingly, tightly restricted to the apical membrane. Multi-label immunostaining demonstrates that γ-Pcdhs are excluded from tight junctions, basolateral adherens junctions, and apical cilia tufts. RT-PCR analysis indicates that, as a whole, the CP expresses most members of the Pcdh-γ gene family. Immunostaining using novel monoclonal antibodies specific for single γ-Pcdh proteins shows that individual epithelial cells differ in their apically localized γ-Pcdh repertoire. Restricted mutation of the Pcdh-γ locus in the choroid plexus and ependyma leads to significant reductions in ventricular volume, without obvious disruptions of epithelial apical-basal polarity. Together, these results suggest an unsuspected role for the γ-Pcdhs in CSF production and demonstrate a surprising molecular heterogeneity in the CP epithelium.
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Affiliation(s)
- Mark A Lobas
- Department of Biology, The University of Iowa, Iowa City, Iowa, USA
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206
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Wostyn P, van Dam D, Audenaert K, de Deyn PP. Genes involved in cerebrospinal fluid production as candidate genes for late-onset Alzheimer's disease: a hypothesis. J Neurogenet 2011; 25:195-200. [PMID: 22023247 DOI: 10.3109/01677063.2011.620191] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
In rare patients with autosomal dominant, early-onset Alzheimer's disease (AD), pathogenic mutations in the genes encoding β-amyloid precursor protein, and the γ-secretase-complex components presenilin-1 and presenilin-2 appear to result in β-amyloid (Aβ) overproduction. The pathological accumulation of Aβ in the far more common late-onset AD is more likely to be the result of deficient clearance of Aβ. There is evidence that production and turnover of cerebrospinal fluid (CSF) help to clear toxic molecules such as Aβ from the interstitial fluid space of the brain to the bloodstream. CSF production and turnover have been shown to be decreased in aging and in pathological conditions, such as normal pressure hydrocephalus and AD. Reduced formation of CSF, with diminished clearance of Aβ, may play an important role in the onset and progression of AD. If reduced CSF turnover is a risk factor for AD, then its incidence ought to be increased under conditions of CSF circulatory failure. In this paper, the authors hypothesize that genes and variations of genes involved in the CSF production and absorption may contribute to the pathogenesis of late-onset AD.
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Affiliation(s)
- Peter Wostyn
- Department of Psychiatry, PC Sint-Amandus, Beernem, Belgium.
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207
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Blocher J, Eckert I, Elster J, Wiefek J, Eiffert H, Schmidt H. Aquaporins AQP1 and AQP4 in the cerebrospinal fluid of bacterial meningitis patients. Neurosci Lett 2011; 504:23-7. [PMID: 21896312 DOI: 10.1016/j.neulet.2011.08.049] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2011] [Revised: 08/04/2011] [Accepted: 08/22/2011] [Indexed: 12/11/2022]
Abstract
Aquaporins facilitate water transport through cell membranes. Due to the localization of AQP1 and AQP4 in the brain, they might contribute to cerebral edema. Our study aimed to determine whether AQP1 and AQP4 can be measured in cerebrospinal fluid (CSF), and whether there is a difference in AQP1 and AQP4 concentration between patients with bacterial meningitis (BM) and healthy controls. AQP1 and AQP4 concentrations in CSF from 35 patients with BM and 27 controls were analyzed using a commercial ELISA. The mean concentration of AQP1 in CSF was significantly elevated in patients with BM (BM: 3.8±3.4ng/ml, controls: 0.8±0.5ng/ml; p<0.001). AQP4 had a tendency to be increased, however the difference was not significant (BM: 1.8±3.1ng/ml, controls: 0.1±0.2ng/ml; p=0.092). AQP1 and AQP4 in CSF of BM patients were inversely correlated (r=-0.47, p=0.004). We could not find any other correlation between concentration of AQP1 or AQP4 in CSF and CSF leukocytes, lactate, protein, albumin CSF/serum ratio, age, a prediction score, an outcome score or the Glasgow Coma Scale at admission in patients with BM. Control patients displayed a correlation between AQP1 and the albumin CSF/serum ratio (r=0.390, p=0.040). This is the first study that detected AQP1 and AQP4 in CSF. Whether the significant elevation of AQP1 is due to a higher expression and subsequent shedding into CSF or a BM-induced cell damage needs to be determined.
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Affiliation(s)
- J Blocher
- Department of Neurology, University Medical Center Göttingen, Robert-Koch-Str. 40, 37075 Göttingen, Germany
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208
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Paul L, Madan M, Rammling M, Chigurupati S, Chan SL, Pattisapu JV. Expression of aquaporin 1 and 4 in a congenital hydrocephalus rat model. Neurosurgery 2011; 68:462-73. [PMID: 21135737 DOI: 10.1227/neu.0b013e3182011860] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Hydrocephalus occurs because of an imbalance of bulk fluid flow in the brain, and aquaporins (AQPs) play pivotal roles in cerebral water movement as essential mediators during edema and fluid accumulation. AQP1 is a water channel found in the choroid plexus (CP), and AQP4 is expressed at the brain-CSF interfaces and astrocytic end feet; excessive fluid accumulation may involve expression of changes in these AQPs during various stages of hydrocephalus. OBJECTIVE To determine the alterations of CP AQP1 expression in congenital hydrocephalus; detect hydrocephalus-induced AQP1 expression in the cortical parenchyma, ependyma, and pia mater of hydrocephalic animals; and evaluate AQP4 expression in congenital hydrocephalus through progressive stages of the condition. METHODS We evaluated differential expression of AQPs 1 and 4 in the congenital hydrocephalus Texas rat at postnatal days 5, 10, and 26 in isolated CP and cortex by enzyme-linked immunosorbent assay, Western blot, quantitative reverse transcriptase polymerase chain reaction, and immunohistochemistry. RESULTS The CP exhibited a 34% decrease in AQP1 expression in young hydrocephalic pups (postnatal days 5 and 10), which became normal (postnatal day 26) just before death. With advancing hydrocephalus, expression of AQPs 1 and 4 increased at the brain-CSF interfaces; AQP1 was localized to the endothelium of cortical capillaries with increased AQP4 expression in surrounding astrocytes end feet. AQP1 expression level was increased in the pia mater, with prominent AQP4 expression in the subpial layers. Subependymal capillaries expressed AQP1 in the endothelium, with increasing AQP4 expression in surrounding astrocytes. Hydrocephalic animals (postnatal day 26) had significant nonendothelial (CD34) AQP1 expression in the septal nucleus of the basal forebrain, an area affected by increased intracranial pressure. CONCLUSION Biphasic AQP1 expression in the CP with increased AQPs 1 and 4 at the brain-fluid interfaces may indicate compensatory mechanisms to regulate choroidal cerebrospinal fluid secretion and increase parenchymal fluid absorption in the high-pressure hydrocephalic condition.
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Affiliation(s)
- Leena Paul
- Burnett School of Biomedical Science, College of Medicine, University of Central Florida Orlando, Florida, USA.
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209
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Cui Y, Bastien DA. Water transport in human aquaporin-4: molecular dynamics (MD) simulations. Biochem Biophys Res Commun 2011; 412:654-9. [PMID: 21856282 DOI: 10.1016/j.bbrc.2011.08.019] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Accepted: 08/05/2011] [Indexed: 12/15/2022]
Abstract
Aquaporin-4 (AQP4) is the predominant water channel in the central nervous system, where it has been reported to be involved in many pathophysiological roles including water transport. In this paper, the AQP4 tetramer was modeled from its PDB structure file, embedded in a palmitoyl-oleoyl-phosphatidyl-choline (POPC) lipid bilayer, solvated in water, then minimized and equilibrated by means of molecular dynamics simulations. Analysis of the equilibrated structure showed that the central pore along the fourfold axis of the tetramers is formed with hydrophobic amino acid residues. In particular, Phe-195, Leu-191 and Leu-75, form the narrowest part of the pore. Therefore water molecules are not expected to transport through the central pore, which was confirmed by MD simulations. Each monomer of the AQP4 tetramers forms a channel whose walls consist mostly of hydrophilic residues. There are eight water molecules in single file observed in each of the four channels, transporting through the selectivity filter containing Arg-216, His-201, Phe-77, Ala-210, and the two conserved Asn-Pro-Ala (NPA) motifs containing Asn-213 and Asn-97. By using Brownian dynamics fluctuation-dissipation-theorem (BD-FDT), the overall free-energy profile was obtained for water transporting through AQP4 for the first time, which gives a complete map of the entire channel of water permeation.
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Affiliation(s)
- Yubao Cui
- Department of Physics, University of Texas at San Antonio, San Antonio, TX 78249, USA.
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210
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Orešković D, Klarica M. Development of hydrocephalus and classical hypothesis of cerebrospinal fluid hydrodynamics: facts and illusions. Prog Neurobiol 2011; 94:238-58. [PMID: 21641963 DOI: 10.1016/j.pneurobio.2011.05.005] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Revised: 05/13/2011] [Accepted: 05/18/2011] [Indexed: 11/30/2022]
Abstract
According to the classical hypothesis of the cerebrospinal fluid (CSF) hydrodynamics, CSF is produced inside the brain ventricles, than it circulates like a slow river toward the cortical subarachnoid space, and finally it is absorbed into the venous sinuses. Some pathological conditions, primarily hydrocephalus, have also been interpreted based on this hypothesis. The development of hydrocephalus is explained as an imbalance between CSF formation and absorption, where more CSF is formed than is absorbed, which results in an abnormal increase in the CSF volume inside the cranial CSF spaces. It is believed that the reason for the imbalance is the obstruction of the CSF pathways between the site of CSF formation and the site of its absorption, which diminishes or prevents CSF outflow from the cranium. In spite of the general acceptance of the classical hypothesis, there are a considerable number of experimental results that do not support such a hypothesis and the generally accepted pathophysiology of hydrocephalus. A recently proposed new working hypothesis suggests that osmotic and hydrostatic forces at the central nervous system microvessels are crucial for the regulation of interstial fluid and CSF volume which constitute a functional unit. Based on that hypothesis, the generally accepted mechanisms of hydrocephalus development are not plausible. Therefore, the recent understanding of the correlation between CSF physiology and the development of hydrocephalus has been thoroughly presented, analyzed and evaluated, and new insights into hydrocephalus etiopathology have been proposed, which are in accordance with the experimental data and the new working hypothesis.
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Affiliation(s)
- D Orešković
- Ruđer Bošković Institute, Department of Molecular Biology, Bijenička 54, 10 000 Zagreb, Croatia.
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211
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Wostyn P, Van Dam D, Audenaert K, De Deyn PP. Increased Cerebrospinal Fluid Production as a Possible Mechanism Underlying Caffeine's Protective Effect against Alzheimer's Disease. Int J Alzheimers Dis 2011; 2011:617420. [PMID: 21660211 PMCID: PMC3109764 DOI: 10.4061/2011/617420] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2010] [Revised: 03/12/2011] [Accepted: 03/29/2011] [Indexed: 12/22/2022] Open
Abstract
Alzheimer's disease (AD), the most common type of dementia among older people, is characterized by the accumulation of β-amyloid (Aβ) senile plaques and neurofibrillary tangles composed of hyperphosphorylated tau in the brain. Despite major advances in understanding the molecular etiology of the disease, progress in the clinical treatment of AD patients has been extremely limited. Therefore, new and more effective therapeutic approaches are needed. Accumulating evidence from human and animal studies suggests that the long-term consumption of caffeine, the most commonly used psychoactive drug in the world, may be protective against AD. The mechanisms underlying the suggested beneficial effect of caffeine against AD remain to be elucidated. In recent studies, several potential neuroprotective effects of caffeine have been proposed. Interestingly, a recent study in rats showed that the long-term consumption of caffeine increased cerebrospinal fluid (CSF) production, associated with the increased expression of Na+-K+ ATPase and increased cerebral blood flow. Compromised function of the choroid plexus and defective CSF production and turnover, with diminished clearance of Aβ, may be one mechanism implicated in the pathogenesis of late-onset AD. If reduced CSF turnover is a risk factor for AD, then therapeutic strategies to improve CSF flow are reasonable. In this paper, we hypothesize that long-term caffeine consumption could exert protective effects against AD at least in part by facilitating CSF production, turnover, and clearance. Further, we propose a preclinical experimental design allowing evaluation of this hypothesis.
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Affiliation(s)
- Peter Wostyn
- Department of Psychiatry, PC Sint-Amandus, Reigerlostraat 10, 8730 Beernem, Belgium
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212
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Surash S, Nemeth P, Chakrabarty A, Chumas P. The conjugation of an AQP1-directed immunotoxin in the study of site-directed therapy within the CNS. Childs Nerv Syst 2011; 27:811-8. [PMID: 21104258 DOI: 10.1007/s00381-010-1336-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2010] [Accepted: 11/09/2010] [Indexed: 11/28/2022]
Abstract
PURPOSE The water channel, aquaporin (AQP)1, is highly specific to the choroid plexus (CP) epithelium within the brain. It is therefore a potential target through which therapeutic agents could be selectively directed to the CP. Here we describe the conjugation of a monoclonal antibody (mAb), raised against an extra-cellular domain of AQP1, to the A chain of ricin (RCA). This reagent should allow study of a highly specific chemical lesion of the CP. METHODS A published method was used to couple the anti-AQP1 mAb to the A chain of ricin using an SPDP cross-linker. The conjugate was purified by Superdex S-200 chromatography. Column fractions were analysed by SDS-PAGE and Western blotting. Fractions containing conjugate were assayed for cytotoxicity on rat CP cells in culture, using a WST-1 viability assay to assess cell death. RESULTS SDS-PAGE and Western blotting demonstrated separation of conjugated anti-AQP1 mAb from unconjugated ricin by the Superdex column. Cultured rat CP cells were killed with an IC(50) of 1.81 μg/ml when exposed to the anti-AQP1 mAb-RCA conjugation reaction products. Selectivity of this reagent was demonstrated by the higher IC(50) exhibited by non-AQP1-expressing primary fibroblast cultures and cultures exposed to the reaction products from the non-specific IgG-RCA conjugation attempt. CONCLUSION We have been able to demonstrate selective cytotoxicity in vitro of an anti-AQP1 mAb-RCA conjugate. We hope that this work will generate further interest in the use of this site-specific conjugate to target the CP in conditions such as hydrocephalus, tumours that arise from here, and other AQP1-expressing tumours.
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Affiliation(s)
- Surash Surash
- Department of Neurosurgery, The General Infirmary at Leeds, Great George Street, Leeds, LS1 3EX, UK.
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213
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Wostyn P, Audenaert K, De Deyn PP. Choroidal Proteins Involved in Cerebrospinal Fluid Production may be Potential Drug Targets for Alzheimer's Disease Therapy. PERSPECTIVES IN MEDICINAL CHEMISTRY 2011; 5:11-7. [PMID: 21487536 PMCID: PMC3072647 DOI: 10.4137/pmc.s6509] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Alzheimer’s disease is known to be the most common form of dementia in the elderly. It is clinically characterized by impairment of cognitive functions, as well as changes in personality, behavioral disturbances and an impaired ability to perform activities of daily living. To date, there are no effective ways to cure or reverse the disease. Genetic studies of early-onset familial Alzheimer’s disease cases revealed causative mutations in the genes encoding β-amyloid precursor protein and the γ-secretase-complex components presenilin-1 and presenilin-2, supporting an important role of β-amyloid in the pathogenesis of Alzheimer’s disease. Compromised function of the choroid plexus and defective cerebrospinal fluid production and turnover, with diminished clearance of β-amyloid, may play an important role in late-onset forms of Alzheimer’s disease. If reduced cerebrospinal fluid turnover is a risk factor for Alzheimer’s disease, then therapeutic strategies to improve cerebrospinal fluid flow are reasonable. However, the role of deficient cerebrospinal fluid dynamics in Alzheimer’s disease and the relevance of choroidal proteins as potential therapeutic targets to enhance cerebrospinal fluid turnover have received relatively little research attention. In this paper, we discuss several choroidal proteins, such as Na+-K+ ATPase, carbonic anhydrase, and aquaporin 1, that may be targets for pharmacological up-regulation of cerebrospinal fluid formation. The search for potentially beneficial drugs useful to ameliorate Alzheimer’s disease by facilitating cerebrospinal fluid production and turnover may be an important area for future research. However, the ultimate utility of such modulators in the management of Alzheimer’s disease remains to be determined. Here, we hypothesize that caffeine, the most commonly used psychoactive drug in the world, may be an attractive therapeutic candidate for treatment of Alzheimer’s disease since long-term caffeine consumption may augment cerebrospinal fluid production. Other potential mechanisms of cognitive protection by caffeine have been suggested by recent studies.
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Affiliation(s)
- Peter Wostyn
- Department of Psychiatry, PC Sint-Amandus, Reigerlostraat 10, 8730 Beernem, Belgium
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214
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Gonzalez AM, Leadbeater WE, Burg M, Sims K, Terasaki T, Johanson CE, Stopa EG, Eliceiri BP, Baird A. Targeting choroid plexus epithelia and ventricular ependyma for drug delivery to the central nervous system. BMC Neurosci 2011; 12:4. [PMID: 21214926 PMCID: PMC3025905 DOI: 10.1186/1471-2202-12-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2010] [Accepted: 01/07/2011] [Indexed: 01/30/2023] Open
Abstract
Background Because the choroid plexus (CP) is uniquely suited to control the composition of cerebrospinal fluid (CSF), there may be therapeutic benefits to increasing the levels of biologically active proteins in CSF to modulate central nervous system (CNS) functions. To this end, we sought to identify peptides capable of ligand-mediated targeting to CP epithelial cells reasoning that they could be exploited to deliver drugs, biotherapeutics and genes to the CNS. Methods A peptide library displayed on M13 bacteriophage was screened for ligands capable of internalizing into CP epithelial cells by incubating phage with CP explants for 2 hours at 37C and recovering particles with targeting capacity. Results Three peptides, identified after four rounds of screening, were analyzed for specific and dose dependant binding and internalization. Binding was deemed specific because internalization was prevented by co-incubation with cognate synthetic peptides. Furthermore, after i.c.v. injection into rat brains, each peptide was found to target phage to epithelial cells in CP and to ependyma lining the ventricles. Conclusion These data demonstrate that ligand-mediated targeting can be used as a strategy for drug delivery to the central nervous system and opens the possibility of using the choroid plexus as a portal of entry into the brain.
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Affiliation(s)
- Ana Maria Gonzalez
- School of Experimental Medicine and Dentistry, University of Birmingham, Edgbaston, UK
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215
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Johanson CE, Stopa EG, McMillan PN. The blood-cerebrospinal fluid barrier: structure and functional significance. Methods Mol Biol 2011; 686:101-131. [PMID: 21082368 DOI: 10.1007/978-1-60761-938-3_4] [Citation(s) in RCA: 136] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The choroid plexus (CP) of the blood-CSF barrier (BCSFB) displays fundamentally different properties than blood-brain barrier (BBB). With brisk blood flow (10 × brain) and highly permeable capillaries, the human CP provides the CNS with a high turnover rate of fluid (∼400,000 μL/day) containing micronutrients, peptides, and hormones for neuronal networks. Renal-like basement membranes in microvessel walls and underneath the epithelium filter large proteins such as ferritin and immunoglobulins. Type IV collagen (α3, α4, and α5) in the subepithelial basement membrane confers kidney-like permselectivity. As in the glomerulus, so also in CP, the basolateral membrane utrophin A and colocalized dystrophin impart structural stability, transmembrane signaling, and ion/water homeostasis. Extensive infoldings of the plasma-facing basal labyrinth together with lush microvilli at the CSF-facing membrane afford surface area, as great as that at BBB, for epithelial solute and water exchange. CSF formation occurs by basolateral carrier-mediated uptake of Na+, Cl-, and HCO3-, followed by apical release via ion channel conductance and osmotic flow of water through AQP1 channels. Transcellular epithelial active transport and secretion are energized and channeled via a highly dense organelle network of mitochondria, endoplasmic reticulum, and Golgi; bleb formation occurs at the CSF surface. Claudin-2 in tight junctions helps to modulate the lower electrical resistance and greater permeability in CP than at BBB. Still, ratio analyses of influx coefficients (Kin) for radiolabeled solutes indicate that paracellular diffusion of small nonelectrolytes (e.g., urea and mannitol) through tight junctions is restricted; molecular sieving is proportional to solute size. Protein/peptide movement across BCSFB is greatly limited, occurring by paracellular leaks through incomplete tight junctions and low-capacity transcellular pinocytosis/exocytosis. Steady-state concentration ratios, CSF/plasma, ranging from 0.003 for IgG to 0.80 for urea, provide insight on plasma solute penetrability, barrier permeability, and CSF sink action to clear substances from CNS.
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Affiliation(s)
- Conrad E Johanson
- Department of Clinical Neuroscience, Alpert Medical School at Brown University, Providence, RI, USA
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216
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Yokozawa T, Lee YA, Cho EJ, Matsumoto K, Park CH, Shibahara N. Anti-aging effects of oligomeric proanthocyanidins isolated from persimmon fruits. Drug Discov Ther 2011; 5:109-18. [DOI: 10.5582/ddt.2011.v5.3.109] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Takako Yokozawa
- Organization for Promotion of Regional Collaboration, University of Toyama
- Institute of Natural Medicine, University of Toyama
| | - Young A Lee
- Institute of Natural Medicine, University of Toyama
| | - Eun Ju Cho
- Department of Food Science and Nutrition, Pusan National University
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217
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Filippidis AS, Kalani MYS, Rekate HL. Hydrocephalus and aquaporins: lessons learned from the bench. Childs Nerv Syst 2011; 27:27-33. [PMID: 20625739 DOI: 10.1007/s00381-010-1227-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2010] [Accepted: 07/01/2010] [Indexed: 11/30/2022]
Abstract
PURPOSE Hydrocephalus is a common disorder of defective cerebrospinal fluid (CSF) turnover. The identification of the aquaporin water channels (AQPs) led to the study of their role in the composition of biological fluids including CSF. The purpose of this study is to review the potential role of aquaporins in the pathogenesis, compensation, and possibly treatment of hydrocephalus. METHODS We performed a MEDLINE search using the terms "aquaporin AND hydrocephalus." The search returned a total of 20 titles. Eleven studies fulfilled the criteria for this review. RESULTS Most studies were performed in animal models. The expression of AQPs in hydrocephalus is significantly altered. Aquaporin-1 levels at the choroid plexus are decreased in most models of hydrocephalus while CSF production and intracranial pressure are reduced in AQP1 knockout mice. In contrast, the expression of AQP4 in hydrocephalus is increased at its sites of expression. Aquaporin-4 knockout mice show a decreased clearance of brain edema via blood-CSF and blood-brain barrier (BBB) pathways and decreased survival in hydrocephalus models. CONCLUSIONS Aquaporin-1 is highly expressed at the choroid plexus and is related to CSF production. Aquaporin-4 is expressed at the ependyma, glia limitans, and at the perivascular end feet processes of astrocytes of the BBB, facilitating the water movement across these tissue interfaces. The observations obtained from animal studies and few cases in humans indicate an adaptive and protective role of AQPs in hydrocephalus by decreasing CSF production and increasing edema clearance. Aquaporins are attractive targets for the pharmaceutical treatment of hydrocephalus.
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Affiliation(s)
- Aristotelis S Filippidis
- Division of Neurological Surgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, 350 West Thomas Road, Phoenix, AZ 85013, USA
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218
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Johanson C, Stopa E, McMillan P, Roth D, Funk J, Krinke G. The distributional nexus of choroid plexus to cerebrospinal fluid, ependyma and brain: toxicologic/pathologic phenomena, periventricular destabilization, and lesion spread. Toxicol Pathol 2010; 39:186-212. [PMID: 21189316 DOI: 10.1177/0192623310394214] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Bordering the ventricular cerebrospinal fluid (CSF) are epithelial cells of choroid plexus (CP), ependyma and circumventricular organs (CVOs) that contain homeostatic transporters for mediating secretion/reabsorption. The distributional pathway ("nexus") of CP-CSF-ependyma-brain furnishes peptides, hormones, and micronutrients to periventricular regions. In disease/toxicity, this nexus becomes a conduit for infectious and xenobiotic agents. The sleeping sickness trypanosome (a protozoan) disrupts CP and downstream CSF-brain. Piperamide is anti-trypanosomic but distorts CP epithelial ultrastructure by engendering hydropic vacuoles; this reflects phospholipidosis and altered lysosomal metabolism. CP swelling by vacuolation may occlude CSF flow. Toxic drug tools delineate injuries to choroidal compartments: cyclophosphamide (vasculature), methylcellulose (interstitium), and piperazine (epithelium). Structurally perturbed CP allows solutes to penetrate the ventricles. There, CSF-borne pathogens and xenobiotics may permeate the ependyma to harm neurogenic stem cell niches. Amoscanate, an anti-helmintic, potently injures rodent ependyma. Ependymal/brain regions near CP are vulnerable to CSF-borne toxicants; this proximity factor links regional barrier breakdown to nearby periventricular pathology. Diverse diseases (e.g., African sleeping sickness, multiple sclerosis) take early root in choroidal, circumventricular, or perivascular loci. Toxicokinetics informs on pathogen, anti-parasitic agent, and auto-antibody distribution along the CSF nexus. CVOs are susceptible to plasma-borne toxicants/pathogens. Countering the physico-chemical and pathogenic insults to the homeostasis-mediating ventricle-bordering cells sustains brain health and fluid balance.
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219
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Damkier HH, Brown PD, Praetorius J. Epithelial pathways in choroid plexus electrolyte transport. Physiology (Bethesda) 2010; 25:239-49. [PMID: 20699470 DOI: 10.1152/physiol.00011.2010] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
A stable intraventricular milieu is crucial for maintaining normal neuronal function. The choroid plexus epithelium produces the cerebrospinal fluid and in doing so influences the chemical composition of the interstitial fluid of the brain. Here, we review the molecular pathways involved in transport of the electrolytes Na+, K+, Cl-, and HCO3(-)across the choroid plexus epithelium.
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Affiliation(s)
- Helle H Damkier
- Department of Anatomy and the Water and Salt Research Center, Aarhus University, Aarhus C, Denmark
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220
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Leenen FH. The central role of the brain aldosterone–“ouabain” pathway in salt-sensitive hypertension. Biochim Biophys Acta Mol Basis Dis 2010; 1802:1132-9. [DOI: 10.1016/j.bbadis.2010.03.004] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2009] [Revised: 03/02/2010] [Accepted: 03/07/2010] [Indexed: 11/29/2022]
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221
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Suon S, Zhao J, Villarreal SA, Anumula N, Liu M, Carangia LM, Renger JJ, Zerbinatti CV. Systemic treatment with liver X receptor agonists raises apolipoprotein E, cholesterol, and amyloid-β peptides in the cerebral spinal fluid of rats. Mol Neurodegener 2010; 5:44. [PMID: 21034469 PMCID: PMC2988784 DOI: 10.1186/1750-1326-5-44] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2010] [Accepted: 10/29/2010] [Indexed: 11/12/2022] Open
Abstract
Background Apolipoprotein E (apoE) is a major cholesterol transport protein found in association with brain amyloid from Alzheimer's disease (AD) patients and the ε4 allele of apoE is a genetic risk factor for AD. Previous studies have shown that apoE forms a stable complex with amyloid β (Aβ) peptides in vitro and that the state of apoE lipidation influences the fate of brain Aβ, i.e., lipid poor apoE promotes Aβ aggregation/deposition while fully lipidated apoE favors Aβ degradation/clearance. In the brain, apoE levels and apoE lipidation are regulated by the liver X receptors (LXRs). Results We investigated the hypothesis that increased apoE levels and lipidation induced by LXR agonists facilitates Aβ efflux from the brain to the cerebral spinal fluid (CSF). We also examined if the brain expression of major apoE receptors potentially involved in apoE-mediated Aβ clearance was altered by LXR agonists. ApoE, cholesterol, Aβ40, and Aβ42 levels were all significantly elevated in the CSF of rats after only 3 days of treatment with LXR agonists. A significant reduction in soluble brain Aβ40 levels was also detected after 6 days of LXR agonist treatment. Conclusions Our novel findings suggest that central Aβ lowering caused by LXR agonists appears to involve an apoE/cholesterol-mediated transport of Aβ to the CSF and that differences between the apoE isoforms in mediating this clearance pathway may explain why individuals carrying one or two copies of APOE ε4 have increased risk for AD.
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Affiliation(s)
- Sokreine Suon
- Department of Neurosymptomatic Disorders, Merck Research Laboratories, West Point, PA 19486, USA.
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222
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Bagnat M, Navis A, Herbstreith S, Brand-Arzamendi K, Curado S, Gabriel S, Mostov K, Huisken J, Stainier DYR. Cse1l is a negative regulator of CFTR-dependent fluid secretion. Curr Biol 2010; 20:1840-5. [PMID: 20933420 DOI: 10.1016/j.cub.2010.09.012] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2010] [Revised: 08/05/2010] [Accepted: 09/02/2010] [Indexed: 01/26/2023]
Abstract
Transport of chloride through the cystic fibrosis transmembrane conductance regulator (CFTR) channel is a key step in regulating fluid secretion in vertebrates [1, 2]. Loss of CFTR function leads to cystic fibrosis [1, 3, 4], a disease that affects the lungs, pancreas, liver, intestine, and vas deferens. Conversely, uncontrolled activation of the channel leads to increased fluid secretion and plays a major role in several diseases and conditions including cholera [5, 6] and other secretory diarrheas [7] as well as polycystic kidney disease [8-10]. Understanding how CFTR activity is regulated in vivo has been limited by the lack of a genetic model. Here, we used a forward genetic approach in zebrafish to uncover CFTR regulators. We report the identification, isolation, and characterization of a mutation in the zebrafish cse1l gene that leads to the sudden and dramatic expansion of the gut tube. We show that this phenotype results from a rapid accumulation of fluid due to the uncontrolled activation of the CFTR channel. Analyses in zebrafish larvae and mammalian cells indicate that Cse1l is a negative regulator of CFTR-dependent fluid secretion. This work demonstrates the importance of fluid homeostasis in development and establishes the zebrafish as a much-needed model system to study CFTR regulation in vivo.
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Affiliation(s)
- Michel Bagnat
- Department of Cell Biology, Duke University School of Medicine, Durham, NC 27710, USA.
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223
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Effect of osmolarity on CSF volume during ventriculo-aqueductal and ventriculo-cisternal perfusions in cats. Neurosci Lett 2010; 484:93-7. [DOI: 10.1016/j.neulet.2010.07.058] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2010] [Revised: 07/09/2010] [Accepted: 07/21/2010] [Indexed: 10/19/2022]
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224
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Ishikawa A, Kono K, Sakae R, Aiba T, Kawasaki H, Kurosaki Y. Altered electrolyte handling of the choroid plexus in rats with glycerol-induced acute renal failure. Biopharm Drug Dispos 2010; 31:455-63. [PMID: 20848389 DOI: 10.1002/bdd.726] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2010] [Revised: 08/10/2010] [Accepted: 08/11/2010] [Indexed: 11/08/2022]
Abstract
The altered electrolyte handling of the choroid plexus was investigated in rats with acute renal failure (ARF) using lithium and rubidium as surrogate markers for sodium and potassium, respectively. Firstly, the transport of these two markers from the plasma to cerebrospinal fluid (CSF) was evaluated after they were concurrently injected into the femoral vein. As a result, their disposition from the plasma to CSF was shown to decrease in ARF rats, but the relationship profile between those two markers was not different from that observed in normal rats, indicating that the decreased disposition of lithium and rubidium occurs without affecting the stoichiometric balance. To clarify the mechanisms accounting for the decreased disposition, an inhibition study was then performed. When bumetanide, an inhibitor of the Na(+) /K(+) /2Cl(-) co-transporter, was directly introduced into the cerebroventricle prior to lithium and rubidium being intravenously administered, a marked increase in the markers' disposition was observed. However, such an increased disposition did not occur when bumetanide was injected into the femoral vein. Other inhibitors, such as amiloride for the Na(+) /H(+) exchanger and ouabain for Na(+) /K(+) -ATPase, did not show any effects on marker disposition regardless of the inhibitor being administered into either the cerebroventricle or femoral vein. These findings suggest that the decreased marker disposition in ARF rats is due to an increased efflux process of the choroid plexus mediated by the Na(+) /K(+) /2Cl(-) co-transporter. That is, electrolyte efflux from the CSF to plasma increases, and thereby the electrolyte influx from the plasma to CSF is counteracted.
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Affiliation(s)
- Atsuko Ishikawa
- Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8530, Japan
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225
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The formation of cerebrospinal fluid: Nearly a hundred years of interpretations and misinterpretations. ACTA ACUST UNITED AC 2010; 64:241-62. [DOI: 10.1016/j.brainresrev.2010.04.006] [Citation(s) in RCA: 229] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2010] [Revised: 04/16/2010] [Accepted: 04/16/2010] [Indexed: 11/17/2022]
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226
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Epidermal growth factor targeting of bacteriophage to the choroid plexus for gene delivery to the central nervous system via cerebrospinal fluid. Brain Res 2010; 1359:1-13. [PMID: 20732308 DOI: 10.1016/j.brainres.2010.08.044] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2010] [Revised: 08/09/2010] [Accepted: 08/16/2010] [Indexed: 10/19/2022]
Abstract
Because the choroid plexus normally controls the production and composition of cerebrospinal fluid and, as such, its many functions of the central nervous system, we investigated whether ligand-mediated targeting could deliver genes to its secretory epithelium. We show here that when bacteriophages are targeted with epidermal growth factor, they acquire the ability to enter choroid epithelial cells grown in vitro as cell cultures, ex vivo as tissue explants or in vivo by intracerebroventricular injection. The binding and internalization of these particles activate EGF receptors on targeted cells, and the dose- and time-dependent internalization of particles is inhibited by the presence of excess ligand. When the phage genome is further reengineered to contain like green fluorescent protein or firefly luciferase under control of the cytomegalovirus promoter, gene expression is detectable in the choroid plexus and ependymal epithelium by immunohistochemistry or by noninvasive imaging, respectively. Taken together, these data support the hypothesis that reengineered ligand-mediated gene delivery should be considered a viable strategy to increase the specificity of gene delivery to the central nervous system and bypass the blood-brain barrier so as to exploit the biological effectiveness of the choroid plexus as a portal of entry into the brain.
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227
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Survival defects of Cryptococcus neoformans mutants exposed to human cerebrospinal fluid result in attenuated virulence in an experimental model of meningitis. Infect Immun 2010; 78:4213-25. [PMID: 20696827 DOI: 10.1128/iai.00551-10] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cryptococcus neoformans is a fungal pathogen that encounters various microenvironments during growth in the mammalian host, including intracellular vacuoles, blood, and cerebrospinal fluid (CSF). Because the CSF is isolated by the blood-brain barrier, we hypothesize that CSF presents unique stresses that C. neoformans must overcome to establish an infection. We assayed 1,201 mutants for survival defects in growth media, saline, and human CSF. We assessed CSF-specific mutants for (i) mutant survival in both human bronchoalveolar lavage (BAL) fluid and fetal bovine serum (FBS), (ii) survival in macrophages, and (iii) virulence using both Caenorhabditis elegans and rabbit models of cryptococcosis. Thirteen mutants exhibited significant survival defects unique to CSF. The mutations of three of these mutants were recreated in the clinical serotype A strain H99: deletions of the genes for a cation ATPase transporter (ena1Δ), a putative NEDD8 ubiquitin-like protein (rub1Δ), and a phosphatidylinositol 4-kinase (pik1Δ). Mutant survival rates in yeast media, saline, and BAL fluid were similar to those of the wild type; however, survival in FBS was reduced but not to the levels in CSF. These mutant strains also exhibited decreased intracellular survival in macrophages, various degrees of virulence in nematodes, and severe attenuation of survival in a rabbit meningitis model. We analyzed the CSF by mass spectrometry for candidate compounds responsible for the survival defect. Our findings indicate that the genes required for C. neoformans survival in CSF ex vivo are necessary for survival and infection in this unique host environment.
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228
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Helland CA, Aarhus M, Knappskog P, Olsson LK, Lund-Johansen M, Amiry-Moghaddam M, Wester K. Increased NKCC1 expression in arachnoid cysts supports secretory basis for cyst formation. Exp Neurol 2010; 224:424-8. [DOI: 10.1016/j.expneurol.2010.05.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2010] [Revised: 04/20/2010] [Accepted: 05/06/2010] [Indexed: 10/19/2022]
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229
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Alvarez JI, Cayrol R, Prat A. Disruption of central nervous system barriers in multiple sclerosis. Biochim Biophys Acta Mol Basis Dis 2010; 1812:252-64. [PMID: 20619340 DOI: 10.1016/j.bbadis.2010.06.017] [Citation(s) in RCA: 231] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2010] [Revised: 06/10/2010] [Accepted: 06/28/2010] [Indexed: 12/30/2022]
Abstract
The delicate microenvironment of the central nervous system (CNS) is protected by the blood-brain barrier (BBB) and the blood-cerebrospinal fluid barrier (BCB). These barriers function in distinct CNS compartments and their anatomical basis lay on the junctional proteins present in endothelial cells for the BBB and in the choroidal epithelium for the BCB. During neuroinflammatory conditions like multiple sclerosis (MS) and its murine model experimental autoimmune encephalomyelitis (EAE), activation or damage of the various cellular components of these barriers facilitate leukocyte infiltration leading to oligodendrocyte death, axonal damage, demyelination and lesion development. This manuscript will review in detail the features of these barriers under physiological and pathological conditions, particularly when focal immune activation promotes the loss of the BBB and BCB phenotype, the upregulation of cell adhesion molecules (CAMs) and the recruitment of immune cells.
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Affiliation(s)
- Jorge Ivan Alvarez
- Neuroimmunology Research Laboratory, Center of Excellence in Neuromics, CHUM-Notre-Dame Hospital, Faculty of Medicine, Université de Montréal, Montréal, Québec, Canada
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230
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Li A, Choi YS, Dziema H, Cao R, Cho HY, Jung YJ, Obrietan K. Proteomic profiling of the epileptic dentate gyrus. Brain Pathol 2010; 20:1077-89. [PMID: 20608933 DOI: 10.1111/j.1750-3639.2010.00414.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The development of epilepsy is often associated with marked changes in central nervous system cell structure and function. Along these lines, reactive gliosis and granule cell axonal sprouting within the dentate gyrus of the hippocampus are commonly observed in individuals with temporal lobe epilepsy (TLE). Here we used the pilocarpine model of TLE in mice to screen the proteome and phosphoproteome of the dentate gyrus to identify molecular events that are altered as part of the pathogenic process. Using a two-dimensional gel electrophoresis-based approach, followed by liquid chromatography-tandem mass spectrometry, 24 differentially expressed proteins, including 9 phosphoproteins, were identified. Functionally, these proteins were organized into several classes, including synaptic physiology, cell structure, cell stress, metabolism and energetics. The altered expression of three proteins involved in synaptic physiology, actin, profilin 1 and α-synuclein was validated by secondary methods. Interestingly, marked changes in protein expression were detected in the supragranular cell region, an area where robust mossy fibers sprouting occurs. Together, these data provide new molecular insights into the altered protein profile of the epileptogenic dentate gyrus and point to potential pathophysiologic mechanisms underlying epileptogenesis.
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Affiliation(s)
- Aiqing Li
- Key Lab. for Organ Failure Research, Education Ministry of P.R. China, Southern Medical University, Guangzhou, China
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231
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Wang HW, Amin MS, El-Shahat E, Huang BS, Tuana BS, Leenen FHH. Effects of central sodium on epithelial sodium channels in rat brain. Am J Physiol Regul Integr Comp Physiol 2010; 299:R222-33. [DOI: 10.1152/ajpregu.00834.2009] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We evaluated the effects of intracerebroventricular (icv) infusion of Na+-rich artificial cerebrospinal fluid (aCSF), with or without the mineralocorticoid receptor (MR) blocker spironolactone, on epithelial Na+ channel (ENaC) subunits and regulators, such as MR, serum/glucocorticoid-inducible kinase 1, neural precursor cells expressed developmentally downregulated 4-like gene, 11β-hydroxylase, and aldosterone synthase, in brain regions of Wistar rats. The effects of icv infusion of the amiloride analog benzamil on brain tissue and CSF Na+ concentration ([Na+]) were also assessed. In the choroid plexus and ependyma of the anteroventral third ventricle, ENaC subunits are present in apical and basal membranes. Na+-rich aCSF increased β-ENaC mRNA and immunoreactivity in the choroid plexus and increased α- and β-ENaC immunoreactivities in the ependyma. Na+-rich aCSF increased α- and β-ENaC-gold-labeled particles in the microvilli of the choroid plexus and in basolateral membranes of the ependyma. Spironolactone only prevented the increase in β-ENaC immunoreactivity in the choroid plexus and ependyma. In the supraoptic nucleus, paraventricular nucleus, and subfornical organ, Na+-rich aCSF did not affect mRNA expression levels of the studied genes. Benzamil significantly increased CSF [Na+] in the control, but not Na+-rich, aCSF group. In contrast, benzamil prevented the increase in hypothalamic tissue [Na+] by Na+-rich aCSF. These results suggest that CSF Na+ upregulates ENaC expression in the brain epithelia, but not in the neurons of hypothalamic nuclei. ENaC in the choroid plexus and ependyma appear to contribute to regulation of Na+ homeostasis in the brain.
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Affiliation(s)
- Hong-Wei Wang
- Hypertension Unit, University of Ottawa Heart Institute, Ottawa, Ontario, Canada
| | - Md Shahrier Amin
- Hypertension Unit, University of Ottawa Heart Institute, Ottawa, Ontario, Canada
| | - Esraa El-Shahat
- Hypertension Unit, University of Ottawa Heart Institute, Ottawa, Ontario, Canada
| | - Bing S. Huang
- Hypertension Unit, University of Ottawa Heart Institute, Ottawa, Ontario, Canada
| | - Balwant S. Tuana
- Hypertension Unit, University of Ottawa Heart Institute, Ottawa, Ontario, Canada
| | - Frans H. H. Leenen
- Hypertension Unit, University of Ottawa Heart Institute, Ottawa, Ontario, Canada
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232
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Hughes AL, Pakhomova A, Brown PD. Regulatory volume increase in epithelial cells isolated from the mouse fourth ventricle choroid plexus involves Na+–H+ exchange but not Na+–K+–2Cl− cotransport. Brain Res 2010; 1323:1-10. [DOI: 10.1016/j.brainres.2009.12.094] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2009] [Revised: 12/03/2009] [Accepted: 12/20/2009] [Indexed: 10/19/2022]
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233
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Abstract
Administration of synthetic or purified peptides directly into the brain ventricles is a method commonly used by neuroscientists for exploring physiological and behavioral functions of gene products. i.v. administration is controlled by the blood-brain barrier, which limits its effectiveness, and current approaches for acute or chronic intracerebroventricular delivery have significant technical drawbacks resulting from both the chemical properties of the delivered substance and the experimental procedures. Here we describe a genetic approach for the delivery of secreted peptides or proteins into the cerebrospinal fluid (CSF). Using a choroid plexus-specific promoter, we established a lentiviral-based system, which offers inducible and reversible delivery of a gene product into the CSF. The functionality of this system was demonstrated by using the overexpression of the two established neuropeptides, corticotropin-releasing factor and gonadotropin-releasing hormone, modulating anxiety-like behavior and estrus cycle, respectively. We show that this choroid plexus-specific lentiviral-based system is a reliable, effective, and adaptable research tool for intracerebroventricular delivery.
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234
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Liu W, Liu Y, Qin XJ, Schmidt S, Hauser MA, Allingham RR. AQP1 and SLC4A10 as candidate genes for primary open-angle glaucoma. Mol Vis 2010; 16:93-7. [PMID: 20101282 PMCID: PMC2810210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Accepted: 01/15/2010] [Indexed: 12/05/2022] Open
Abstract
PURPOSE Recent evidence supports the role of reduced cerebrospinal fluid (CSF) pressure in the pathogenesis of primary open-angle glaucoma (POAG). We investigated the association of variants in two candidate genes that are important in CSF production, aquaporin 1 (AQP1) and solute carrier family 4, sodium bicarbonate transporter, member 10 (SLC4A10), with POAG in the Caucasian population. METHODS POAG subjects (n=382) met the criteria of glaucomatous optic neuropathy with consistent visual field loss. Intraocular pressure was not used as an inclusion criterion. Control subjects (n=363) did not meet any of the inclusion criteria and had no family history of glaucoma. Eleven tagging single nucleotide polymorphisms (SNPs) for AQP1 and SLC4A10 were genotyped in the POAG and control subjects, using allelic discrimination assays. Genotype frequencies were compared between the POAG and control subjects, using logistic regression adjusted for gender. RESULTS There was no statistically significant difference in genotype frequencies between POAG and control subjects for any of the tested SNPs in AQP1 and SLC4A10 (p>0.05). CONCLUSIONS There was no association between common sequence variants in the AQP1 or SLC4A10 genes and POAG in the Caucasian population. This is the first study to investigate the association between these two candidate genes and increased risk for POAG.
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Affiliation(s)
- Wenjing Liu
- Center for Human Genetics, Duke University Eye Center, Duke University Medical Center, Durham, NC
| | - Yutao Liu
- Center for Human Genetics, Duke University Eye Center, Duke University Medical Center, Durham, NC
| | - Xue-Jun Qin
- Center for Human Genetics, Duke University Eye Center, Duke University Medical Center, Durham, NC
| | - Silke Schmidt
- Center for Human Genetics, Duke University Eye Center, Duke University Medical Center, Durham, NC
| | - Michael A. Hauser
- Center for Human Genetics, Duke University Eye Center, Duke University Medical Center, Durham, NC
- Department of Ophthalmology, Duke University Eye Center, Duke University Medical Center, Durham, NC
| | - R. Rand Allingham
- Center for Human Genetics, Duke University Eye Center, Duke University Medical Center, Durham, NC
- Department of Ophthalmology, Duke University Eye Center, Duke University Medical Center, Durham, NC
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235
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Choroid plexus: biology and pathology. Acta Neuropathol 2010; 119:75-88. [PMID: 20033190 DOI: 10.1007/s00401-009-0627-8] [Citation(s) in RCA: 232] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2009] [Revised: 12/12/2009] [Accepted: 12/12/2009] [Indexed: 12/24/2022]
Abstract
The choroid plexus is an epithelial-endothelial vascular convolute within the ventricular system of the vertebrate brain. It consists of epithelial cells, fenestrated blood vessels, and the stroma, dependent on various physiological or pathological conditions, which may contain fibroblasts, mast cells, macrophages, granulocytes or other infiltrates, and a rich extracellular matrix. The choroid plexus is mainly involved in the production of cerebrospinal fluid (CSF) by using the free access to the blood compartment of the leaky vessels. In order to separate blood and CSF compartments, choroid plexus epithelial cells and tanycytes of circumventricular organs constitute the blood-CSF-brain barrier. As non-neuronal cells in the brain and derived from neuroectoderm, choroid plexus epithelia are defined as a subtype of macroglia. The choroid plexus is involved in a variety of neurological disorders, including neurodegenerative, inflammatory, infectious, traumatic, neoplastic, and systemic diseases. Abeta and Biondi ring tangles accumulate in the Alzheimer's disease choroid plexus. In multiple sclerosis, the choroid plexus could represent a site for lymphocyte entry in the CSF and brain, and for presentation of antigens. Recent studies have provided new diagnostic markers and potential molecular targets for choroid plexus papilloma and carcinoma, which represent the most common brain tumors in the first year of life. We here revive some of the classical studies and review recent insight into the biology and pathology of the choroid plexus.
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236
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Nowakowski A, Alonso-Martín S, González-Manchón C, Larrucea S, Fernández D, Vilar M, Cerdán S, Ayuso MS, Parrilla R. Ventricular enlargement associated with the panneural ablation of the podocalyxin gene. Mol Cell Neurosci 2010; 43:90-7. [DOI: 10.1016/j.mcn.2009.09.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2009] [Revised: 09/14/2009] [Accepted: 09/25/2009] [Indexed: 10/20/2022] Open
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237
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Rouault TA, Zhang DL, Jeong SY. Brain iron homeostasis, the choroid plexus, and localization of iron transport proteins. Metab Brain Dis 2009; 24:673-84. [PMID: 19851851 PMCID: PMC2788140 DOI: 10.1007/s11011-009-9169-y] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2009] [Accepted: 08/04/2009] [Indexed: 11/27/2022]
Abstract
Maintenance of appropriate iron homeostasis in the brain is important, but the mechanisms involved in brain iron uptake are incompletely understood. Here, we have analyzed where messenger RNAs that encode iron transport proteins are expressed in the brain, using the Allen Brain atlas, and we conclude that several important iron transporters are highly expressed in the choroid plexus. Based on recent estimates of the surface area of the choroid plexus and on MRI imaging studies of manganese uptake in the brain, we propose that the choroid plexus may have a much greater role than has been previously appreciated in brain iron transport.
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Affiliation(s)
- Tracey A Rouault
- Molecular Medicine Program, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
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238
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Narita K, Kawate T, Kakinuma N, Takeda S. Multiple primary cilia modulate the fluid transcytosis in choroid plexus epithelium. Traffic 2009; 11:287-301. [PMID: 19958467 DOI: 10.1111/j.1600-0854.2009.01016.x] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Functional defects in cilia are associated with various human diseases including congenital hydrocephalus. Previous studies suggested that defects in cilia not only disrupt the flow of cerebrospinal fluid (CSF) generated by motile cilia in ependyma lining the brain ventricles, but also cause increased CSF production at the choroid plexus. However, the molecular mechanisms of CSF overproduction by ciliary dysfunction remain elusive. To dissect the molecular mechanisms, choroid plexus epithelial cells (CPECs) were isolated from porcine brain. These cells expressed clusters of primary cilia on the apical surface. Deciliation of CPECs elevated the intracellular cyclic AMP (cAMP) levels and stimulated basolateral-to-apical fluid transcytosis, without detrimental effects on other morphological and physiological features. The primary cilia possessed neuropeptide FF (NPFF) receptor 2. In deciliated cells, the responsiveness to NPFF was reduced at nanomolar concentrations. Furthermore, CPECs expressed NPFF precursor along with NPFFR2. An NPFFR antagonist, BIBP3226, increased the fluid transcytosis, suggesting the presence of autocrine NPFF signaling in CPECs for a tonic inhibition of fluid transcytosis. These results suggest that the clusters of primary cilia in CPECs act as a sensitive chemosensor to regulate CSF production.
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Affiliation(s)
- Keishi Narita
- Department of Anatomy and Cell Biology, Interdisciplinary School of Medicine & Engineering, University of Yamanashi, 1110 Shimo-Kateau, Chuo, Yamanashi 409-3898, Japan
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239
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Oligomeric proanthocyanidins improve memory and enhance phosphorylation of vascular endothelial growth factor receptor-2 in senescence-accelerated mouse prone/8. Br J Nutr 2009; 103:479-89. [PMID: 19822031 DOI: 10.1017/s0007114509992005] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Senescence-accelerated mouse prone/8 (SAMP8), a murine model of accelerated senescence, shows age-related deficits in learning and memory. We investigated the effect of oligomeric proanthocyanidins (oligomers) on memory impairment using the SAMP8 model involving the oral administration of oligomers for 5 weeks. To analyse memory improvement in SAMP8, we performed Morris water maze, object location and object recognition tests. The oral administration of oligomers improved spatial and object recognition impairment in SAMP8. Expressions of phosphorylated neurofilament-H (P-NF-H, axon marker), microtubule-associated proteins (MAP) 2a and 2b (MAP2; dendrite marker) and synaptophysin were increased in the brains of SAMP8-administered oligomers. In particular, the expression of P-NF-H was significantly elevated in the hippocampal CA1. This indicates that oligomers result in an increase in the densities of axons, dendrites and synapses. To investigate the protective mechanisms of oligomers against brain dysfunction with ageing, we carried out a receptor tyrosine kinase phosphorylation antibody array, and clarified that the administration of oligomers led to an increase in the phosphorylation of vascular endothelial growth factor receptor (VEGFR)-2, suggesting the neuroprotective role of oligomers. The phosphorylation of VEGFR-2 was more greatly increased in the hypothalamus and choroid plexus than in other brain regions of SAMP8. Memory in oligomer-treated mice was impaired by SU1498, a VEGFR-2-specific antagonist. Elucidating the relationship between memory impairment with ageing and VEGFR-2 signalling may provide new suggestions for protection against memory deficit in the ageing brain.
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240
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Amin MS, Reza E, Wang H, Leenen FH. Sodium Transport in the Choroid Plexus and Salt-Sensitive Hypertension. Hypertension 2009; 54:860-7. [DOI: 10.1161/hypertensionaha.108.125807] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
To elucidate the role of epithelial sodium channels (ENaCs) and Na
+
-K
+
-ATPase in Na
+
transport by the choroid plexus, we studied ENaC expression and Na
+
transport in the choroid plexus. Lateral ventricle choroid plexuses were obtained from young male Wistar, Dahl salt–resistant (SS.BN13), and Dahl salt–sensitive (SS/MCW) rats on a regular (0.3%) or high- (8.0%) salt diet. The effects of ENaC blocker benzamil and Na
+
-K
+
-ATPase blocker ouabain on sodium transport were evaluated by measuring the amounts of retained
22
Na
+
and by evaluating intracellular [Na
+
] with Sodium Green fluorescence. In Wistar rats, ENaC distribution was as follows: microvilli, 10% to 30%; cytoplasm, 60% to 80%; and basolateral membrane, 5% to 10%. Benzamil (10
−8
m
) decreased
22
Na
+
retention by 20% and ouabain (10
−3
m
) increased retention by 40%, whereas ouabain and benzamil combined caused no change. Similar changes were noted in intracellular [Na
+
]. In Dahl rats on a regular salt diet, intracellular [Na
+
] was similar, but the amount of retained
22
Na
+
was less in sensitive versus resistant rats. High salt did not affect ENaC mRNA or protein, nor the benzamil induced decreases in retained
22
Na
+
or intracellular [Na
+
] in either strain. However, high salt increased intracellular [Na
+
] and attenuated the increase in uptake of
22
Na
+
by ouabain in resistant but not sensitive rats, suggesting a decrease in Na
+
-K
+
-ATPase activity only in resistant rats. These findings suggest that both ENaC and Na
+
-K
+
-ATPase regulate Na
+
transport in the choroid plexus. Aberrant regulation of Na
+
transport and of Na
+
-K
+
-ATPase activity, but not of ENaCs, might contribute to the increase in cerebrospinal fluid [Na
+
] in Dahl salt-sensitive rats on a high-salt diet.
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Affiliation(s)
- Md Shahrier Amin
- From the Hypertension Unit (M.S.A., E.R., H.W., F.H.H.L.), University of Ottawa Heart Institute, Ottawa, Ontario, Canada; Department of Cellular and Molecular Medicine (M.S.A., E.R., F.H.H.L.), University of Ottawa, Ottawa, Ontario, Canada
| | - Erona Reza
- From the Hypertension Unit (M.S.A., E.R., H.W., F.H.H.L.), University of Ottawa Heart Institute, Ottawa, Ontario, Canada; Department of Cellular and Molecular Medicine (M.S.A., E.R., F.H.H.L.), University of Ottawa, Ottawa, Ontario, Canada
| | - Hongwei Wang
- From the Hypertension Unit (M.S.A., E.R., H.W., F.H.H.L.), University of Ottawa Heart Institute, Ottawa, Ontario, Canada; Department of Cellular and Molecular Medicine (M.S.A., E.R., F.H.H.L.), University of Ottawa, Ottawa, Ontario, Canada
| | - Frans H.H. Leenen
- From the Hypertension Unit (M.S.A., E.R., H.W., F.H.H.L.), University of Ottawa Heart Institute, Ottawa, Ontario, Canada; Department of Cellular and Molecular Medicine (M.S.A., E.R., F.H.H.L.), University of Ottawa, Ottawa, Ontario, Canada
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241
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Adijanto J, Banzon T, Jalickee S, Wang NS, Miller SS. CO2-induced ion and fluid transport in human retinal pigment epithelium. ACTA ACUST UNITED AC 2009; 133:603-22. [PMID: 19468075 PMCID: PMC2713148 DOI: 10.1085/jgp.200810169] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
In the intact eye, the transition from light to dark alters pH, [Ca2+], and [K] in the subretinal space (SRS) separating the photoreceptor outer segments and the apical membrane of the retinal pigment epithelium (RPE). In addition to these changes, oxygen consumption in the retina increases with a concomitant release of CO2 and H2O into the SRS. The RPE maintains SRS pH and volume homeostasis by transporting these metabolic byproducts to the choroidal blood supply. In vitro, we mimicked the transition from light to dark by increasing apical bath CO2 from 5 to 13%; this maneuver decreased cell pH from 7.37 ± 0.05 to 7.14 ± 0.06 (n = 13). Our analysis of native and cultured fetal human RPE shows that the apical membrane is significantly more permeable (≈10-fold; n = 7) to CO2 than the basolateral membrane, perhaps due to its larger exposed surface area. The limited CO2 diffusion at the basolateral membrane promotes carbonic anhydrase–mediated HCO3 transport by a basolateral membrane Na/nHCO3 cotransporter. The activity of this transporter was increased by elevating apical bath CO2 and was reduced by dorzolamide. Increasing apical bath CO2 also increased intracellular Na from 15.7 ± 3.3 to 24.0 ± 5.3 mM (n = 6; P < 0.05) by increasing apical membrane Na uptake. The CO2-induced acidification also inhibited the basolateral membrane Cl/HCO3 exchanger and increased net steady-state fluid absorption from 2.8 ± 1.6 to 6.7 ± 2.3 µl × cm−2 × hr−1 (n = 5; P < 0.05). The present experiments show how the RPE can accommodate the increased retinal production of CO2 and H2O in the dark, thus preventing acidosis in the SRS. This homeostatic process would preserve the close anatomical relationship between photoreceptor outer segments and RPE in the dark and light, thus protecting the health of the photoreceptors.
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Affiliation(s)
- Jeffrey Adijanto
- Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, MD 20742, USA
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242
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Abbott NJ, Patabendige AAK, Dolman DEM, Yusof SR, Begley DJ. Structure and function of the blood-brain barrier. Neurobiol Dis 2009; 37:13-25. [PMID: 19664713 DOI: 10.1016/j.nbd.2009.07.030] [Citation(s) in RCA: 3153] [Impact Index Per Article: 210.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2009] [Revised: 07/13/2009] [Accepted: 07/25/2009] [Indexed: 02/08/2023] Open
Abstract
Neural signalling within the central nervous system (CNS) requires a highly controlled microenvironment. Cells at three key interfaces form barriers between the blood and the CNS: the blood-brain barrier (BBB), blood-CSF barrier and the arachnoid barrier. The BBB at the level of brain microvessel endothelium is the major site of blood-CNS exchange. The structure and function of the BBB is summarised, the physical barrier formed by the endothelial tight junctions, and the transport barrier resulting from membrane transporters and vesicular mechanisms. The roles of associated cells are outlined, especially the endfeet of astrocytic glial cells, and pericytes and microglia. The embryonic development of the BBB, and changes in pathology are described. The BBB is subject to short and long-term regulation, which may be disturbed in pathology. Any programme for drug discovery or delivery, to target or avoid the CNS, needs to consider the special features of the BBB.
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Affiliation(s)
- N Joan Abbott
- King's College London, Blood-Brain Barrier Group, Pharmaceutical Science Division, Hodgkin Building, Guy's Campus, London SE1 1UL, UK.
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243
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Thiéry JC, Lomet D, Bougoin S, Malpaux B. Turnover rate of cerebrospinal fluid in female sheep: changes related to different light-dark cycles. Cerebrospinal Fluid Res 2009; 6:9. [PMID: 19653900 PMCID: PMC2731051 DOI: 10.1186/1743-8454-6-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2009] [Accepted: 08/04/2009] [Indexed: 04/18/2024] Open
Abstract
BACKGROUND Sheep are seasonal breeders. The key factor governing seasonal changes in the reproductive activity of the ewe is increased negative feedback of estradiol at the level of the hypothalamus under long-day conditions. It has previously been demonstrated that when gonadotropin secretions are inhibited during long days, there is a higher concentration of estradiol in the cerebrospinal fluid (CSF) than during short days. This suggests an involvement of the CSF and choroid plexus in the neuroendocrine regulatory loop, but the mechanisms underlying this phenomenon remain unknown. One possible explanation of this difference in hormonal content is an effect of concentration or dilution caused by variations in CSF secretion rate. The aim of this study was thus to investigate changes in the CSF turnover rate related to light-dark cycles. METHODS The turnover rate of the CSF was estimated by measuring the time taken for the recovery of intraventricular pressure (IVP) after removal of a moderate volume (0.5 to 2 ml) of CSF (slope in mmHg/min). The turnover rate was estimated three times in the same group of sheep: during a natural period of decreasing day-length corresponding to the initial period when gonadotropin activity is stimulated (SG1), during a long-day inhibitory period (IG), and finally during a short-day stimulatory period (SG2). RESULTS The time taken and the speed of recovery of initial IVP differed between groups: 8 min 30 sec, 0.63 +/- 0.07 mmHg/min(SG1), 11 min 1 sec, 0.38 +/- 0.06 mmHg/min (IG) and 9 min 0 sec, 0.72 +/- 0.15 mmHg/min (SG2). Time changes of IVP differed between groups (ANOVA, p < 0.005, SG1 different from IG, p < 0.05). The turnover rate in SG2: 183.16 +/- 23.82 mul/min was not significantly different from SG1: 169. 23 +/- 51.58 mul/min (Mann-Whitney test, p = 0.41), but was significantly different from IG: 71.33 +/- 16.59 mul/min (p = 0.016). CONCLUSION This study shows that the turnover rate of CSF in ewes changes according to the light-dark cycle; it is increased during short day periods and reduced in long day periods. This phenomenon could account for differences in hormonal concentrations in the CSF in this seasonal species.
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Affiliation(s)
- Jean-Claude Thiéry
- UMR: INRA – CNRS – Université François Rabelais de Tours – Haras nationaux 37380 Nouzilly, France
| | - Didier Lomet
- UMR: INRA – CNRS – Université François Rabelais de Tours – Haras nationaux 37380 Nouzilly, France
| | - Sylvain Bougoin
- UMR: INRA – CNRS – Université François Rabelais de Tours – Haras nationaux 37380 Nouzilly, France
| | - Benoit Malpaux
- UMR: INRA – CNRS – Université François Rabelais de Tours – Haras nationaux 37380 Nouzilly, France
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244
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Sibley CP. Understanding placental nutrient transfer--why bother? New biomarkers of fetal growth. J Physiol 2009; 587:3431-40. [PMID: 19417095 PMCID: PMC2742272 DOI: 10.1113/jphysiol.2009.172403] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2009] [Accepted: 04/30/2009] [Indexed: 12/13/2022] Open
Abstract
The placenta, in general and the physiology of maternofetal nutrient transfer is under-researched compared to other organs with epithelial transport function, as evidenced, for example, by publication numbers. This report provides reasons why more researchers should become involved in this topic. First, the syncytiotrophoblast, the transporting epithelium of the placenta, though having many basic cell physiology properties similar to those of other transporting epithelia, has several properties which are markedly different. Better information on these might help fundamental understanding of how epithelia in general function as well as improving knowledge of how the syncytiotrophoblast operates. Second, the synctiotrophoblast has a key role in controlling fetal growth, not only by transporting nutrients and waste products of metabolism but also because it increasingly appears to be one site, perhaps even the dominant site, in which integration of, sometimes conflicting, signals between mother and fetus takes place. Finally, better understanding of placental nutrient transfer and especially of how it is regulated by maternal and fetal signals could provide better information on the placental phenotype in fetal growth disorders--information which might contribute to providing better biomarkers which the obstetrician could use to improve early diagnosis of these disorders.
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Affiliation(s)
- C P Sibley
- Maternal and Fetal Health Research Centre, Research School of Clinical and Laboratory Sciences, University of Manchester, Research Floor, St Mary's Hospital, Manchester M13 OJH, UK.
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245
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246
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Ooi LY, Walker BR, Bodkin PA, Whittle IR. Idiopathic intracranial hypertension: Can studies of obesity provide the key to understanding pathogenesis? Br J Neurosurg 2009; 22:187-94. [DOI: 10.1080/02688690701827340] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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247
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Changes in cerebrospinal fluid nerve growth factor levels during chick embryonic development. J Clin Neurosci 2009; 16:1334-7. [PMID: 19581095 DOI: 10.1016/j.jocn.2009.03.023] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2008] [Revised: 03/15/2009] [Accepted: 03/18/2009] [Indexed: 02/02/2023]
Abstract
In the early stages of brain development, cells within the ependymal lining of the neural tube are thought to secrete cerebrospinal fluid (CSF), the so-called neural tube fluid (NTF), whereas before fusion of the neural folds, the neuroepithelium that lines the inside of the neural tube is in contact with amniotic fluid. As the neural tube closes, a membrane formed from these cells invaginates to form the specialized choroid plexus. The choroid plexus is a highly vascularized epithelial cell structure that secretes proteins, including growth factors, into the CSF. Embryonic CSF (e-CSF) contains high concentrations of proteins compared to adult CSF. CSF has been reported to contain nerve growth factor (NGF) and other neurotrophic factors. In this study, total protein concentration and NGF level in e-CSF samples from chick embryos were measured using a dye-based protein assay, enzyme-linked immunosorbent assay (ELISA) and Western blot. The total protein concentration and NGF levels in the CSF decreased from days E10 to E16. There was a rapid increase in total protein content on days E17 and E18, and thereafter the levels decreased from day E19 to day E21. Days E17 and E18 coincide with the onset of neuron migration, proliferation and organization of the cytoarchitecture of the developing cerebral cortex. After that time the total protein concentration and NGF levels decrease until hatching. Since CSF is in contact with the cerebral cortical germinal epithelium, changes in the protein concentration in the CSF could affect neuroepithelial cell proliferation, survival and migration. It is concluded that NGF is not only a constant component of CSF during chick embryogenesis but it might also be involved in cerebral cortical development.
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248
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Wood A. A Darwinian perspective: Vomiting, the meninges and increased intracranial pressure. Med Hypotheses 2009; 73:123-4. [DOI: 10.1016/j.mehy.2009.02.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2009] [Accepted: 02/01/2009] [Indexed: 10/21/2022]
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249
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Lowery LA, Sive H. Totally tubular: the mystery behind function and origin of the brain ventricular system. Bioessays 2009; 31:446-58. [PMID: 19274662 DOI: 10.1002/bies.200800207] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
A unique feature of the vertebrate brain is the ventricular system, a series of connected cavities which are filled with cerebrospinal fluid (CSF) and surrounded by neuroepithelium. While CSF is critical for both adult brain function and embryonic brain development, neither development nor function of the brain ventricular system is fully understood. In this review, we discuss the mystery of why vertebrate brains have ventricles, and whence they originate. The brain ventricular system develops from the lumen of the neural tube, as the neuroepithelium undergoes morphogenesis. The molecular mechanisms underlying this ontogeny are described. We discuss possible functions of both adult and embryonic brain ventricles, as well as major brain defects that are associated with CSF and brain ventricular abnormalities. We conclude that vertebrates have taken advantage of their neural tube to form the essential brain ventricular system.
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Affiliation(s)
- Laura Anne Lowery
- Whitehead Institute for Biomedical Research, Nine Cambridge Center, Cambridge, MA 02142, USA
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250
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Linninger AA, Xenos M, Sweetman B, Ponkshe S, Guo X, Penn R. A mathematical model of blood, cerebrospinal fluid and brain dynamics. J Math Biol 2009; 59:729-59. [DOI: 10.1007/s00285-009-0250-2] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2008] [Revised: 01/13/2009] [Indexed: 10/21/2022]
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