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Distribution by Scientific Domains

Chemistry	51%
Medical Sciences	14%
Life Sciences	14%
Information Science and Computing	5%
Business, Economics, Finance and Accounting	5%
3 Other Domains	11%

Distribution within Chemistry

Organic Chemistry	60%
General & Introductory Chemistry	27%

Selected Abstracts

Direct Access to Furanosidic Eight-Membered Ulosonic Esters from cis -,,,-Epoxy Aldehydes

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 4 2003
Claudia H. Sugisaki
Abstract Direct access to bicyclic precursors of octulosonic acids is achieved by treatment of differentially (or not) protected ,,,-bis(silyloxy) cis -,,,-epoxy aldehydes with ethyl 2-(trimethylsilyloxy)-2-propenoate in the presence of boron trifluoride,diethyl ether. An X-ray crystallographic structure of a bicycle (compound 33a) was obtained and used to determine the absolute configurations of the different stereogenic centers and thus the diastereoselective preference of the aldol reaction (syn) and the regioselectivity of the epoxide ring-opening (C-6 atom). Functionalization and opening of the bicyclic compound to afford octulosonic analogues in their furanoside forms was studied. An octulosonic 8-phosphate analogue has been synthesized. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source]

Innentitelbild: Direct Access to Isolated Biomolecules under Ambient Conditions (Angew. Chem.

ANGEWANDTE CHEMIE, Issue 13 2010
13/2010)
Sprays mit hohen Dichten an unsolvatisierten Biomolekül-Ionen werden unter Umgebungsbedingungen durch eine neue Methode der Elektrosprayionisation (ESI) erzeugt. R. Zenobi und Mitarbeiter schildern in ihrer Zuschrift auf S.,2408,ff., wie dieses Verfahren die Palette an massenspektrometrischen Techniken zur Untersuchung von Biomolekülen erweitert. [source]

Direct Access to Isolated Biomolecules under Ambient Conditions,

ANGEWANDTE CHEMIE, Issue 13 2010
Konstantin Chingin
Thermisches Verdampfen ist für den Transfer von nichtflüchtigen Substanzen in die Gasphase extrem ineffizient, weil es zu einem raschen chemischen Abbau kommt (links). Daher werden oft weiche Ionisierungsmethoden wie ESI oder MALDI genutzt, um solche Substanzen für die Untersuchung mit MS in die Gasphase zu überführen (rechts). Eine neue Methode wurde nun entwickelt, die isolierte nichtflüchtige Biomoleküle bei Umgebungsbedingungen zugänglich macht. [source]

ChemInform Abstract: Titanium Binolate Catalyzed Aminolysis of meso Aziridines: A Highly Enantioselective and Direct Access to 1,2-Diamines.

CHEMINFORM, Issue 42 2009
Saravanan Peruncheralathan
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

ChemInform Abstract: Direct Access to Anthranilic Acid Derivatives via CO2 Incorporation Reaction Using Arynes.

CHEMINFORM, Issue 2 2009
Hiroto Yoshida
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

ChemInform Abstract: [8 + 2] and [8 + 3] Cyclization Reactions of Alkenyl Carbenes and 8-Azaheptafulvenes: Direct Access to Tetrahydro-1-azaazulene and Cyclohepta[b]pyridinone Derivatives.

CHEMINFORM, Issue 33 2008
Jose Barluenga
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

Asymmetric Catalytic Coupling of Organoboranes, Alkynes, and Imines with a Removable (Trialkylsilyloxy)ethyl Group , Direct Access to Enantiomerically Pure Primary Allylic Amines.

CHEMINFORM, Issue 46 2004
Sejal J. Patel
Abstract For Abstract see ChemInform Abstract in Full Text. [source]

A Rapid and Direct Access to Symmetrical/Unsymmetrical 3,4-Diarylmaleimides and Pyrrolin-2-ones.

CHEMINFORM, Issue 34 2004
Manojit Pal
Abstract For Abstract see ChemInform Abstract in Full Text. [source]

A Direct Access to 3-(2-Oxoalkyl)indoles via Aluminum Chloride Induced C,C Bond Formation.

CHEMINFORM, Issue 33 2004
Manojit Pal
Abstract For Abstract see ChemInform Abstract in Full Text. [source]

Facile Construction and Divergent Transformation of Polycyclic Isoxazoles: Direct Access to Polyketide Architectures.

CHEMINFORM, Issue 25 2003
Jeffrey W. Bode
Abstract For Abstract see ChemInform Abstract in Full Text. [source]

[8+2] and [8+3] Cyclization Reactions of Alkenyl Carbenes and 8-Azaheptafulvenes: Direct Access to Tetrahydro-1-azaazulene and Cyclohepta[b]pyridinone Derivatives

CHEMISTRY - AN ASIAN JOURNAL, Issue 4 2008
José Barluenga Prof.
Abstract The reactivity of Fischer alkenyl carbenes toward 8-azaheptafulvenes is examined. Alkenyl carbenes react with 8-azaheptafulvenes with complete regio- and stereoselectivity through formal [8+3] and [8+2] heterocyclization reactions, which show an unprecedented dependence on the C, substituent at the alkenyl carbene complex. Thus, the formal [8+3] heterocyclization reaction is completely favored in carbene complexes that bear a coordinating moiety to give tetrahydrocyclohepta[b]pyridin-2-ones. Otherwise, alkenyl carbenes that lack appropriate coordinating groups undergo a formal [8+2] cyclization with 8-azaheptafulvenes to give compounds that bear a tetrahydroazaazulene structure. A likely mechanism for these reactions would follow well-established models and would involve a 1,4-addition/cyclization in the case of the [8+2] cyclization or a 1,2-addition/[1,2] shift,metal-promoted cyclization for the [8+3] reaction. The presence of a coordinating moiety in the carbene would favor the [1,2] metal shift through transition-state stabilization to lead to the [8+3] product. All these processes provide an entry into the tetrahydroazaazulene and cycloheptapyridone frameworks present in the structure of biologically active molecules. Se ha estudiado la reactividad de alquenilcarbenos de Fischer con 8-azaheptafulvenos. Los alquenilcarbenos reaccionan con 8-azaheptafulvenos a través de reacciones de heterociclación formales [8+3] y [8+2] con completa regioselectividad y estereoselectividad, mostrando una dependencia del sustituyente C, del complejo alquenilcarbeno sin precedentes. Así, en los complejos carbeno que contienen un resto coordinante la reacción de heterociclación formal [8+3] se favorece completamente para dar tetrahidrociclohepta[b]piridin-2-onas. Por otra parte, los alquenilcarbenos que carecen de grupos coordinantes apropiados, experimentan una ciclación formal [8+2] con los 8-azaheptafulvenos para dar compuestos con estructura de tetrahidroazuleno. Un mecanismo probable para estas reacciones se fundamenta en modelos bien establecidos e implica una adición 1,4/ciclación en el caso de la ciclación [8+2] o una adición 1,2/ciclación promovida por una migración 1,2 del metal en el caso de la reacción [8+3]. La presencia de un resto coordinante en el carbeno favorece la migración 1,2 del metal a través de una estabilización del estado de transición, conduciendo al producto [8+3]. Todos estos procesos representan una vía de acceso a los esqueletos de tetrahidroazuleno y cicloheptapiridona presentes en la estructura de moléculas biológicamente activas. [source]

Direct Access to Furanosidic Eight-Membered Ulosonic Esters from cis -,,,-Epoxy Aldehydes

LOVD: Easy creation of a locus-specific sequence variation database using an "LSDB-in-a-box" approach,

HUMAN MUTATION, Issue 2 2005
Ivo F.A.C. Fokkema
Abstract The completion of the human genome project has initiated, as well as provided the basis for, the collection and study of all sequence variation between individuals. Direct access to up-to-date information on sequence variation is currently provided most efficiently through web-based, gene-centered, locus-specific databases (LSDBs). We have developed the Leiden Open (source) Variation Database (LOVD) software approaching the "LSDB-in-a-Box" idea for the easy creation and maintenance of a fully web-based gene sequence variation database. LOVD is platform-independent and uses PHP and MySQL open source software only. The basic gene-centered and modular design of the database follows the recommendations of the Human Genome Variation Society (HGVS) and focuses on the collection and display of DNA sequence variations. With minimal effort, the LOVD platform is extendable with clinical data. The open set-up should both facilitate and promote functional extension with scripts written by the community. The LOVD software is freely available from the Leiden Muscular Dystrophy pages (www.DMD.nl/LOVD/). To promote the use of LOVD, we currently offer curators the possibility to set up an LSDB on our Leiden server. Hum Mutat 26(2), 1,6, 2005. © 2005 Wiley-Liss, Inc. [source]

A toolkit for the characterization of CCD cameras for transmission electron microscopy

ACTA CRYSTALLOGRAPHICA SECTION D, Issue 1 2010
M. Vulovic
Charge-coupled devices (CCD) are nowadays commonly utilized in transmission electron microscopy (TEM) for applications in life sciences. Direct access to digitized images has revolutionized the use of electron microscopy, sparking developments such as automated collection of tomographic data, focal series, random conical tilt pairs and ultralarge single-particle data sets. Nevertheless, for ultrahigh-resolution work photographic plates are often still preferred. In the ideal case, the quality of the recorded image of a vitrified biological sample would solely be determined by the counting statistics of the limited electron dose the sample can withstand before beam-induced alterations dominate. Unfortunately, the image is degraded by the non-ideal point-spread function of the detector, as a result of a scintillator coupled by fibre optics to a CCD, and the addition of several inherent noise components. Different detector manufacturers provide different types of figures of merit when advertising the quality of their detector. It is hard for most laboratories to verify whether all of the anticipated specifications are met. In this report, a set of algorithms is presented to characterize on-axis slow-scan large-area CCD-based TEM detectors. These tools have been added to a publicly available image-processing toolbox for MATLAB. Three in-house CCD cameras were carefully characterized, yielding, among others, statistics for hot and bad pixels, the modulation transfer function, the conversion factor, the effective gain and the detective quantum efficiency. These statistics will aid data-collection strategy programs and provide prior information for quantitative imaging. The relative performance of the characterized detectors is discussed and a comparison is made with similar detectors that are used in the field of X-ray crystallography. [source]

The platelet window: examining receptor regulated second messenger processes in psychosis and depression

ACTA NEUROPSYCHIATRICA, Issue 6 2003
M Berk
Peripheral markers of psychiatric illness provide a potentially important window into the pathophysiology of a number of psychiatric illnesses. Direct access to pathophysiological processes is fraught with difficulty. However, receptor-regulated second messenger-mediated calcium shifts are an accessible and practical method by which to examine changes in a clinical population. This is possible because platelets and neurons share some physiological features. The platelet intracellular calcium response to receptor stimulation has previously been used as a peripheral marker of psychiatric illness across a range of neurotransmitters, including serotonin, dopamine and glutamate. This review considers the specificity and selectivity of this response and its use in psychotic and mood disorders. [source]

A Windows-based interface for teaching image processing

COMPUTER APPLICATIONS IN ENGINEERING EDUCATION, Issue 2 2010
Melvin Ayala
Abstract The use of image processing in research represents a challenge to the scientific community interested in its various applications but is not familiar with this area of expertise. In academia as well as in industry, fundamental concepts such as image transformations, filtering, noise removal, morphology, convolution/deconvolution among others require extra efforts to be understood. Additionally, algorithms for image reading and visualization in computers are not always easy to develop by inexperienced researchers. This type of environment has lead to an adverse situation where most students and researchers develop their own image processing code for operations which are already standards in image processing, a redundant process which only exacerbates the situation. The research proposed in this article, with the aim to resolve this dilemma, is to propose a user-friendly computer interface that has a dual objective which is to free students and researchers from the learning time needed for understanding/applying diverse imaging techniques but to also provide them with the option to enhance or reprogram such algorithms with direct access to the software code. The interface was thus developed with the intention to assist in understanding and performing common image processing operations through simple commands that can be performed mostly by mouse clicks. The visualization of pseudo code after each command execution makes the interface attractive, while saving time and facilitating to users the learning of such practical concepts. © 2009 Wiley Periodicals, Inc. Comput Appl Eng Educ 18: 213,224, 2010; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.20171 [source]

Statistical optimization of octree searches

COMPUTER GRAPHICS FORUM, Issue 6 2008
Rener Castro
Abstract This work emerged from the following observation: usual search procedures for octrees start from the root to retrieve the data stored at the leaves. But as the leaves are the farthest nodes to the root, why start from the root? With usual octree representations, there is no other way to access a leaf. However, hashed octrees allow direct access to any node, given its position in space and its depth in the octree. Search procedures take the position as an input, but the depth remains unknown. This work proposes to estimate the depth of an arbitrary node through a statistical optimization of the average cost of search procedures. As the highest costs of these algorithms are obtained when starting from the root, this method improves on both the memory footprint by the use of hashed octrees, and execution time through the proposed optimization. [source]

The Impact of Regulation FD on Institutional Investor Informativeness

FINANCIAL MANAGEMENT, Issue 3 2010
Douglas O. Cook
Although there is conflicting evidence and resulting skepticism regarding the value provided by professional investment management, Gibson, Safieddine, and Sonti (2004) document institutional investor informativeness relative to seasoned equity offering (SEO) purchases. We find that Regulation Fair Disclosure's significantly reduces institutional investors' ability to identify mispriced SEO firms. Informativeness is diminished not by investors following analysts who have experienced a reduction in forecasting accuracy, but limiting investors' direct access to private information. This information loss is replaced by reliance on a greater number of public information variables resulting in less consideration for prudence proxies and a liquidity motive and more for higher price momentum. [source]

The Development of a Convergent and Efficient Enantioselective Synthesis of the Bengamides via a Common Polyol Intermediate

HELVETICA CHIMICA ACTA, Issue 12 2002
Robert
An efficient, general synthetic route to the bengamide family of antitumor agents from a common polyol thioester is described. Consecutive aldol condensations afford the protected polyol thioester side chain suitable for coupling to the bengamides. A novel chiral-phase-transfer-catalyzed enantioselective alkylation affords the properly functionalized caprolactams required for the synthesis of more-complex members of the bengamide family. Use of the methyl 2-naphthyl ether protecting group, compatible with the boron Lewis acids required for enantioselective aldol condensation, allows direct access to all the bengamides. [source]

A metric for space

HIPPOCAMPUS, Issue 12 2008
Edvard I. Moser
Abstract Not all areas of neuronal systems investigation have matured to the stage where computation can be understood at the microcircuit level. In mammals, insights into cortical circuit functions have been obtained for the early stages of sensory systems, where signals can be followed through networks of increasing complexity from the receptors to the primary sensory cortices. These studies have suggested how neurons and neuronal networks extract features from the external world, but how the brain generates its own codes, in the higher-order nonsensory parts of the cortex, has remained deeply mysterious. In this terra incognita, a path was opened by the discovery of grid cells, place-modulated entorhinal neurons whose firing locations define a periodic triangular or hexagonal array covering the entirety of the animal's available environment. This array of firing is maintained in spite of ongoing changes in the animal's speed and direction, suggesting that grid cells are part of the brain's metric for representation of space. Because the crystal-like structure of the firing fields is created within the nervous system itself, grid cells may provide scientists with direct access to some of the most basic operational principles of cortical circuits. © 2008 Wiley-Liss, Inc. [source]

Recognition-Controlled Assembly of Nanoparticles Using Photochemically Crosslinked Recognition-Induced Polymersomes,

ADVANCED MATERIALS, Issue 16 2006
J. Thibault
Photocrosslinking of recognition-induced polymersomes provides robust hollow spheres with tunable sizes from 3 to 15,,m (see figure). These capsules selectively integrate complementary nanoparticles into their walls, providing direct access to assemblies. [source]

Modeling and simulation of mixed traffic on a prioritized shared medium

INTERNATIONAL JOURNAL OF NETWORK MANAGEMENT, Issue 1 2003
Jeffrey J. Evans
Network access systems (NAS) such as digital loop carriers (DLC) are increasingly utilizing a shared medium, such as Hybrid Fiber Coax (HFC) to provide point-to-multi-point access from the public switched telephone network (PSTN) to the end user (consumer). New services, such as direct access to the packet switched network (PSN, WWW) have been added to DLC equipment in such a way as to provide for a prioritized set of services over a shared medium in an effort to take advantage of otherwise unused bandwidth. The introduction of such services requires the modeling and analysis of these network access systems. This becomes complex when considering the variability in different service type traffic characteristics. This work identifies a traffic engineering problem of prioritized circuit switched and packet switched (PSTN/PSN) traffic over the same shared medium as it may relate to "perceived" quality of service (QoS). Copyright © 2002 John Wiley & Sons, Ltd. [source]

Zinc-Salen-Catalyzed Asymmetric Alkynylation of Alkyl Acylsilanes

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2009
Feng-Quan Li
Abstract Optically active tertiary propargylic alcohols are useful and versatile building blocks in organic synthesis, and their direct access by enantioselective addition of alkyne nucleophiles to ketones has achieved significant progress over the last ten years. In view of the potential applications of acylsilanes as useful synthetic equivalents of aldehydes, we described a general catalytic enantioselective addition of terminal alkynes to alkyl acylsilanes. After reaction optimization involving variation of solvent, temperature, catalyst ratio and various catalysts screen, the in situ generated Zn-salen complex was chosen as catalyst. With hexane as solvent, the silylated tertiary propargylic alcohols were obtained in satisfactory yields and ees for both aliphatic and aromatic alkynes. [source]

Visual constraints in written word recognition: evidence from the optimal viewing-position effect

JOURNAL OF RESEARCH IN READING, Issue 3 2005
Marc Brysbaert
In this paper we review the literature on visual constraints in written word processing. We notice that not all letters are equally visible to the reader. The letter that is most visible is the letter that is fixated. The visibility of the other letters depends on the distance between the letters and the fixation location, whether the letters are outer or inner letters of the word, and whether the letters lie to the left or to the right of the fixation location. Because of these three factors, word recognition depends on the viewing position. In languages read from left to right, the optimal viewing position is situated between the beginning and the middle of the word. This optimal viewing position is the result of an interplay of four variables: the distance between the viewing position and the farthest letter, the fact that the word beginning is usually more informative than the word end, the fact that during reading words have been recognised a lot of times after fixation on this letter position and the fact that stimuli in the right visual field have direct access to the left cerebral hemisphere. For languages read from right to left, the first three variables pull the optimal viewing position towards the right side of the word (which is the word beginning), but the fourth variable counteracts these forces to some extent. Therefore, the asymmetry of the optimum viewing-position curve is less clear in Hebrew and Arabic than in French and Dutch. [source]

The production of provitamin A-rich vegetables in home-gardens as a means of addressing vitamin A deficiency in rural African communities

JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 3 2007
Mieke Faber
Abstract Vitamin A deficiency remains a public health problem in the developing world. The highest prevalence of vitamin A deficiency is in Africa and Asia (>30%). Dietary modification, a long-term strategy to address vitamin A deficiency, complements food fortification and vitamin A supplementation programmes. Provitamin A carotenoids from foods of plant origin are more affordable than preformed vitamin A from animal foods, and many resource-poor households rely on yellow/orange-fleshed vegetables and fruits and dark-green leafy vegetables as their main source of vitamin A. The provitamin A carotenoid content in plant foods varies widely and differences among cultivars of the same food exist. Several factors influence the bioavailability of provitamin A carotenoids. The potential contribution of plant foods to vitamin A status depends on the retention of provitamin A carotenoids after storage, preparation and processing. Home-gardens can provide households with direct access to provitamin A-rich vegetables that are not readily available or within their financial reach. The components and critical issues of home-garden projects are described. Copyright © 2006 Society of Chemical Industry [source]

The making of fetal surgery

PRENATAL DIAGNOSIS, Issue 7 2010
Jan A. Deprest
Abstract Fetal diagnosis prompts the question for fetal therapy in highly selected cases. Some conditions are suitable for in utero surgical intervention. This paper reviews historically important steps in the development of fetal surgery. The first invasive fetal intervention in 1963 was an intra-uterine blood transfusion. It took another 20 years to understand the pathophysiology of other candidate fetal conditions and to develop safe anaesthetic and surgical techniques before the team at the University of California at San Francisco performed its first urinary diversion through hysterotomy. This procedure would be abandoned as renal and pulmonary function could be just as effectively salvaged by ultrasound-guided insertion of a bladder shunt. Fetoscopy is another method for direct access to the feto-placental unit. It was historically used for fetal visualisation to guide biopsies or for vascular access but was also abandoned following the introduction of high-resolution ultrasound. Miniaturisation revived fetoscopy in the 1990s, since when it has been successfully used to operate on the placenta and umbilical cord. Today, it is also used in fetuses with congenital diaphragmatic hernia (CDH), in whom lung growth is triggered by percutaneous tracheal occlusion. It can also be used to diagnose and treat urinary obstruction. Many fetal interventions remain investigational but for a number of conditions randomised trials have established the role of in utero surgery, making fetal surgery a clinical reality in a number of fetal therapy programmes. The safety of fetal surgery is such that even non-lethal conditions, such as myelomeningocoele repair, are at this moment considered a potential indication. This, as well as fetal intervention for CDH, is currently being investigated in randomised trials. Copyright © 2010 John Wiley & Sons, Ltd. [source]

Credit Availability and the Structure of the Homebuilding Industry

REAL ESTATE ECONOMICS, Issue 4 2008
Brent W. Ambrose
We investigate the role of disruptions to the structure of the homebuilding industry due to fluctuations in the availability of bank credit. We find a sustained decline in the large private homebuilder market share series over the period from 1988 to 1993 when many banks with deteriorated health reduced their lending in order to raise capital ratios. Regression analysis at the metropolitan statistical area level supports the hypothesis that, in areas where banks were less well capitalized and had more problem construction loans, the market shares of large private homebuilders that relied primarily on bank credit to finance their production suffered at the expense of the public homebuilders that had better access to external funds, in large part due to their direct access to public capital markets. [source]

Large Interarcuate Spaces in the Cervical Vertebral Column of the Tyrolean Mountain Sheep

ANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 1 2003
E. Turkof
Summary Large interarcual spaces have been described between the arcus vertebrae C5/C6 and C6/C7 in the cervical vertebral column of Nubian goats. This aperture enables direct access to spinal cord and rootlets without the need to perform a hemilaminectomy. The present study was performed in order to determine whether these large interarcual spaces can also be found in the vertebral column of the Tyrolean mountain sheep, as this small ruminant, which is anatomically very similar to the Nubian goat, is frequently used for experimental purposes at the Surgical University Clinic in Austria. The carcasses of 10 sheep (six females, four males; range of age: 2.5,6 years, range of weight: 52,89 kg) were dissected and the vertebral column was exposed. All 10 sheep showed elliptic openings between the fourth cervical and the first thoracal vertebrae. Three sheep had additional openings between the first and the second thoracal vertebrae. All openings were covered solitarily by the ligamentum flavum and under this ligamentum lay the spinal cord without any further osseous or ligamentous protection. These findings are not mentioned in the common textbooks of veterinary anatomy and deserve attention, as they can be a step forward towards non-traumatic experimental surgery on the spinal cord. [source]

Localizing central nervous system immune surveillance: Meningeal antigen-presenting cells activate T cells during experimental autoimmune encephalomyelitis

ANNALS OF NEUROLOGY, Issue 4 2009
Pia Kivisäkk MD
Objective The onset of neurological signs in experimental autoimmune encephalomyelitis is tightly associated with infiltration and reactivation of T cells in the central nervous system. The anatomic localization of the initial T cell-antigen-presenting cell (APC) interactions leading to reactivation of T cells in the central nervous system is, however, still unclear. We hypothesized that activated CD4+ T cells gain direct access to the subarachnoid space and become reactivated on encounter with cognate antigen in this compartment. Methods C57Bl/6 mice were immunized with MOG35-55, and interactions between CD4+ T cells and major histocompatibility class II+ APCs in the subarachnoid space were investigated using flow cytometry, confocal microscopy of leptomeningeal whole-mount preparations, time-lapse microscopy of leptomeningeal explants, and in vitro proliferation assays. Results CD4+ T cells, polarized to produce Th1/Th17 cytokines, accumulated in the subarachnoid space early during the course of experimental autoimmune encephalomyelitis, before CD4+ T cells were detected in the spinal cord parenchyma. At this time point, leptomeningeal but not parenchymal CD4+ T cells incorporated bromodeoxyuridine, indicating local proliferation of CD4+ T cells in the subarachnoid space. Time-lapse microscopy indicated that these CD4+ T cells actively scanned the tissue and interacted with local major histocompatibility class II+ APCs, resulting in long-lasting interactions between CD4+ T cells and major histocompatibility class II+ APCs, suggestive of immunological synapses. Interpretation These results support the concept that immune surveillance of the central nervous system involves the subarachnoid space and indicate that the leptomeninges play an important role in experimental autoimmune encephalomyelitis initiation. Ann Neurol 2009;65:457,469 [source]

Design and Test of a Vascular Access Device

ARTIFICIAL ORGANS, Issue 5 2000
Gijsbertus Jacob Verkerke
Abstract: Transarterial left ventricular assist devices (LVADs), such as the Hemopump, IABP, and PUCA-pump, are meant to be introduced into the body via the femoral or axillary artery without major surgery. For certain applications, introduction is performed directly into the aorta via an open thorax procedure. A prototype of a vascular access device has been realized that allows direct access into the aorta as an alternative for the common surgical graft anastomosis suturing technique. The device consists of a metal tube acting as a circular knife to cut a hole in the aortic wall, a screw to store the removed part of the aortic wall, and a plastic tube that is introduced through the hole and tightly connected to the aortic wall. The device could be placed without aortic clamping. The device has been tested on a slaughterhouse porcine aorta. A low-pressurized aorta appeared to be the worst case; thus, two animal experiments in the low-pressurized pulmonary artery were performed. No leakage occurred for pressures between 40 and 300 mm Hg. [source]