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  • Chemistry  (1,757)
  • Analytical Chemistry and Spectroscopy  (243)
  • Animals  (201)
  • 1
    Publication Date: 2012-06-16
    Description: Autism spectrum disorder (ASD) is a group of conditions characterized by impaired social interaction and communication, and restricted and repetitive behaviours. ASD is a highly heritable disorder involving various genetic determinants. Shank2 (also known as ProSAP1) is a multi-domain scaffolding protein and signalling adaptor enriched at excitatory neuronal synapses, and mutations in the human SHANK2 gene have recently been associated with ASD and intellectual disability. Although ASD-associated genes are being increasingly identified and studied using various approaches, including mouse genetics, further efforts are required to delineate important causal mechanisms with the potential for therapeutic application. Here we show that Shank2-mutant (Shank2(-/-)) mice carrying a mutation identical to the ASD-associated microdeletion in the human SHANK2 gene exhibit ASD-like behaviours including reduced social interaction, reduced social communication by ultrasonic vocalizations, and repetitive jumping. These mice show a marked decrease in NMDA (N-methyl-D-aspartate) glutamate receptor (NMDAR) function. Direct stimulation of NMDARs with D-cycloserine, a partial agonist of NMDARs, normalizes NMDAR function and improves social interaction in Shank2(-/-) mice. Furthermore, treatment of Shank2(-/-) mice with a positive allosteric modulator of metabotropic glutamate receptor 5 (mGluR5), which enhances NMDAR function via mGluR5 activation, also normalizes NMDAR function and markedly enhances social interaction. These results suggest that reduced NMDAR function may contribute to the development of ASD-like phenotypes in Shank2(-/-) mice, and mGluR modulation of NMDARs offers a potential strategy to treat ASD.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Won, Hyejung -- Lee, Hye-Ryeon -- Gee, Heon Yung -- Mah, Won -- Kim, Jae-Ick -- Lee, Jiseok -- Ha, Seungmin -- Chung, Changuk -- Jung, Eun Suk -- Cho, Yi Sul -- Park, Sae-Geun -- Lee, Jung-Soo -- Lee, Kyungmin -- Kim, Daesoo -- Bae, Yong Chul -- Kaang, Bong-Kiun -- Lee, Min Goo -- Kim, Eunjoon -- England -- Nature. 2012 Jun 13;486(7402):261-5. doi: 10.1038/nature11208.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biological Sciences, KAIST, Daejeon 305-701, Korea.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22699620" target="_blank"〉PubMed〈/a〉
    Keywords: Adaptor Proteins, Signal Transducing/*genetics ; Animals ; Antimetabolites/pharmacology ; *Autistic Disorder/genetics/metabolism ; Behavior, Animal/*drug effects/physiology ; Benzamides/*pharmacology ; Cycloserine/*pharmacology ; Disease Models, Animal ; Female ; Male ; Mice ; Mice, Inbred C57BL ; Nerve Tissue Proteins/*genetics ; Pyrazoles/*pharmacology ; Receptors, N-Methyl-D-Aspartate/*agonists/*metabolism
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 2
    ISSN: 0192-8651
    Keywords: Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The relative stabilities of the keto and enol forms [Δ E0 (enol-keto)] and the energy barriers to enolization of the keto forms [Δ E≠ (transition state-keto)] for CH3COR (R = CH3, H, F, and CN) and CH3CHY (Y = CH2, NH, and S) are investigated theoretically by Hartree-Fock and Möoller-Plesset second-order calculations with 6-31G** basis sets. Specific and bulk solvent effects are considered by incorporating one water molecule and applying the self-consistent reaction field (SCRF) method to the reaction system, respectively. The Δ E0MP2 values are all positive, in agreement with the lower stability of the enol form in the gas phase as well as in solution. In contrast to a relatively small effect of specific as well as bulk solvation on Δ E0, there is a large lowering of Δ E≠ (by ca. 30 kcal/mol) when solvent effects are accounted for. In general, both Δ E0 and Δ E≠ are depressed in solution and hence enolization is favored thermodynamically as well as kinetically. The keto form is strongly stabilized by a π donor, whereas the enol isomer is stabilized by a π as well as a σ-acceptor substituent, R. As a result, substituent R = F is the most unfavorable whereas R = CN is the most favorable for the enolization. The water catalyzed enolization in the neutral water proceeds concertedly, but carbon deprotonation is more important than carbonyl-oxygen protonation by water in the rate determining step. © 1997 by John Wiley & Sons, Inc.
    Additional Material: 1 Ill.
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  • 3
    Publication Date: 2016-01-19
    Description: Many procedures in modern clinical medicine rely on the use of electronic implants in treating conditions that range from acute coronary events to traumatic injury. However, standard permanent electronic hardware acts as a nidus for infection: bacteria form biofilms along percutaneous wires, or seed haematogenously, with the potential to migrate within the body and to provoke immune-mediated pathological tissue reactions. The associated surgical retrieval procedures, meanwhile, subject patients to the distress associated with re-operation and expose them to additional complications. Here, we report materials, device architectures, integration strategies, and in vivo demonstrations in rats of implantable, multifunctional silicon sensors for the brain, for which all of the constituent materials naturally resorb via hydrolysis and/or metabolic action, eliminating the need for extraction. Continuous monitoring of intracranial pressure and temperature illustrates functionality essential to the treatment of traumatic brain injury; the measurement performance of our resorbable devices compares favourably with that of non-resorbable clinical standards. In our experiments, insulated percutaneous wires connect to an externally mounted, miniaturized wireless potentiostat for data transmission. In a separate set-up, we connect a sensor to an implanted (but only partially resorbable) data-communication system, proving the principle that there is no need for any percutaneous wiring. The devices can be adapted to sense fluid flow, motion, pH or thermal characteristics, in formats that are compatible with the body's abdomen and extremities, as well as the deep brain, suggesting that the sensors might meet many needs in clinical medicine.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kang, Seung-Kyun -- Murphy, Rory K J -- Hwang, Suk-Won -- Lee, Seung Min -- Harburg, Daniel V -- Krueger, Neil A -- Shin, Jiho -- Gamble, Paul -- Cheng, Huanyu -- Yu, Sooyoun -- Liu, Zhuangjian -- McCall, Jordan G -- Stephen, Manu -- Ying, Hanze -- Kim, Jeonghyun -- Park, Gayoung -- Webb, R Chad -- Lee, Chi Hwan -- Chung, Sangjin -- Wie, Dae Seung -- Gujar, Amit D -- Vemulapalli, Bharat -- Kim, Albert H -- Lee, Kyung-Mi -- Cheng, Jianjun -- Huang, Younggang -- Lee, Sang Hoon -- Braun, Paul V -- Ray, Wilson Z -- Rogers, John A -- F31MH101956/MH/NIMH NIH HHS/ -- Howard Hughes Medical Institute/ -- England -- Nature. 2016 Feb 4;530(7588):71-6. doi: 10.1038/nature16492. Epub 2016 Jan 18.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA. ; Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA. ; Department of Neurological Surgery, Washington University School of Medicine, St Louis, Missouri 63110, USA. ; KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 136-701, Republic of Korea. ; Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA. ; Department of Engineering Science and Mechanics, Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802, USA. ; Institute of High Performance Computing, Singapore 138632, Singapore. ; Department of Anesthesiology, Washington University School of Medicine, St Louis, Missouri 63110, USA. ; Department of Biomicrosystem Technology, Korea University, Seoul 136-701, South Korea. ; Department of Biochemistry and Molecular Biology, Korea University College of Medicine, Seoul 136-713, South Korea. ; Weldon School of Biomedical Engineering, School of Mechanical Engineering, The Center for Implantable Devices, Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, USA. ; School of Mechanical Engineering, Purdue University, West Lafayette, Indiana 47907, USA. ; Department of Mechanical Engineering, Civil and Environmental Engineering, Materials Science and Engineering, and Skin Disease Research Center, Northwestern University, Evanston, Illinois 60208, USA. ; Department of Biomedical Engineering, College of Health Science, Korea University, Seoul 136-703, South Korea. ; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26779949" target="_blank"〉PubMed〈/a〉
    Keywords: *Absorbable Implants/adverse effects ; Administration, Cutaneous ; Animals ; Body Temperature ; Brain/*metabolism/surgery ; Electronics/*instrumentation ; Equipment Design ; Hydrolysis ; Male ; Monitoring, Physiologic/adverse effects/*instrumentation ; Organ Specificity ; Pressure ; *Prostheses and Implants/adverse effects ; Rats ; Rats, Inbred Lew ; *Silicon ; Telemetry/instrumentation ; Wireless Technology/instrumentation
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 4
    ISSN: 0887-624X
    Keywords: dinuclear metallocene ; polysiloxane bridge ; heterogenation ; ethylene polymerization ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The polymerization of ethylene was studied by using a series of polysiloxane-bridged dinuclear zirconocenes [(SiMe2O)nSiMe2(C5H4)2][(C9H7)ZrCl2]2 (7, n = 1; 8, n = 2; 9, n = 3), the corresponding mononuclear zirconocene (C5H5)(C9H7)ZrCl2, 10, and the pentamethylene-bridged dinuclear zirconocene [(CH2)5(C5H4)2][(C9H7)-ZrCl2]2, 13. From the polymerization studies using these catalysts it was found that (i) activities of the polysiloxane dinuclear zirconocenes 7-9 wre lower than that of the corresponding mononuclear zirconocene 10, (ii) molecular weights of polyethylenes produced by the dinuclear metallocenes are greater than that of polyethylene produced by the mononuclear metallocene, (iii) the complex 9 holding the longest bridging ligand exhibited the highest activity but produced a polymer having the smallest molecular weight among the polysiloxane-bridged dinuclear zirconocenes, and (iv) the pentamethylene-bridged dinuclear metallocene 13 showed higher activity than the complexes 7-9 and the mononuclear zirconocene 10. The formation of the lowest molecular weight of polyethylene by 9 was attributed to the influence of electron withdrawal caused by the Lewis acid-base interaction between the acidic aluminum of the cocatalyst and the basic oxygen at the polysiloxane linkage as well as the lack of a steric problem. An increase in steric congestion around the metal center led to not only a decrease in catalytic activity due to preventing facile monomer access to the active site but also an increase in the molecular weight of polyethylenes due to supressing β-H elimination. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 3717-3728, 1997
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  • 5
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Data reported here and previously indicate that when dextrin is hydrolyzed in the presence of immobilized glucoamylase, use of a larger average molecular weight substrate leads to lower overall rates of hydrolysis, while the maltose concentration during the bulk of the reaction and the maximum glucose concentration are lower than when the soluble form of the enzyme is employed under the same conditions. Computer simulation of the system demonstrated that all three observations were caused by pore diffusion limitation: the first by slow diffusion of substrate, the second by slow diffusion of intermediates, and the third by slow diffusion of glucose. Follow-up experiments with glucoamylase immobilized to particles of different sizes confirmed this finding, as results with the smallest beads were identical to those with soluble glucoamylase.
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  • 6
    ISSN: 1022-1336
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Two kinds of the trisiloxane-bridged dinuclear titanium metallocene-type complexes were synthesized. They are monocyclopentadienyl and biscyclopentadienyl dinuclear titanocenes with trisiloxane bridges. The above complexes with modified methylaluminoxane (MMAO) cocatalyst initiate the polymerizations of ethylene and styrene to produce high-density polyethylene and syndiotactic polystyrene. In addition, a copolymer of ethylene and styrene was obtained.
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  • 7
    ISSN: 1022-1336
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The disiloxane-bridged zirconocene complexes, tetramethyldisiloxanediylbis (cyclopentadienyl)zirconium dichloride and tetramethyldisiloxanediylbis(cyclopentadienyl) dimethylzirconium initiate the homopolymerization of ethene as well as the copolymerization of ethene and α-olefin with a modified methylaluminoxane as cocatalyst. The catalyst systems give resonable activity but the molecular weight of polyethene decreases drastically with increasing polymerization temperature.
    Additional Material: 2 Ill.
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  • 8
    ISSN: 0268-2575
    Keywords: penicillin G ; emulsion liquid membrane ; decomposition ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: To confirm the applicability for the extraction of penicillin G by an emulsion liquid membrane (ELM), the degree of decomposition of penicillin G during extraction was theoretically calculated. Decomposition was less than 1% provided that the initial sodium carbonate concentration in the internal phase was correctly determined, which proved the applicability of the ELM process. The procedure to determine the initial carbonate concentration in the internal phase was also described in order that the pH in the internal phase should be within the relatively stable range for penicillin G at the end of the extraction.
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  • 9
    ISSN: 0268-2575
    Keywords: penicillin G ; emulsion liquid membrane ; optimum extraction conditions ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Penicillin G extraction by an emulsion liquid membrane (ELM) was investigated. The effects of surfactants, diluents, and carrier mixtures, together with their combined effects on the initial extraction rate and the emulsion stability were examined. Surfactants, diluents, and carriers used were Span80 (sorbitan monooleate)/ECA4360J (nonionic polyamine), n-butyl acetate/kerosene, and DOA (dioctylamine)/Amberlite LA-2 (secondary amine), respectively. The optimum extraction conditions were found to be 20% (v/v) of Span80 in ECA4360J as a surfactant, kerosene as a diluent and Amberlite LA-2 as a carrier.
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  • 10
    ISSN: 0887-624X
    Keywords: polyimides ; electrooptics ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Aromatic polyimides with side chain nonlinear optical chromophores have been investigated through a facile two-step synthetic route. First, various poly(hydroxy imide)s have been synthesized by direct thermal imidization of diaminophenol dihydrochloride salt and aromatic dianhydride monomers. The resulting polyimides bearing phenolic hydroxy groups were found to react easily with the terminal hydroxy group on the chromophores via the Mitsunobu condensation to give corresponding polyimides with high optical nonlinearities and good solubility in common organic solvents. Detailed physical properties showed that these polyimides have a molecular weight (Mw) of 31,000 and high glass transition temperature above 220°C, ensuring a long-term alignment stability at elevated temperature. The electrooptic coefficients, r33, of the electrically poled polymer films were in the range 1.8-7.6 pm/V at 1.3 μm. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 301-307, 1998
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