bluuebunny/crossref_metadata_2025 huggingface dataset:
Progesterone induces Apoptosis in TRAIL‐resistant ovarian cancer cells by circumventing c‐FLIPL overexpression
Authors: Syed Viqar , Mukherjee Kasturi , Godoy‐Tundidor Sonia , Ho Shuk‐Mei
Published: March 2007

Tumor necrosis factor‐related apoptosis‐inducing ligand (TRAIL) holds great potential as an anticancer drug, since it induces selective cell death in cancer cells but not in normal ones. However, cancer cells often acquire resistance to TRAIL, which hinders its clinical efficacy. We previously demonstrated that progesterone triggers apoptosis in human ovarian cancer (OCa) cells. In the present study, we evaluated the prospect of utilizing progestins in combination with TRAIL to enhance cell death in TRAIL‐sensitive (OVCA 420, OVCA 429, and OVCA 433) and ‐resistant (OVCA 432) OCa cell lines. TRAIL sensitivity (60–80% cell kill) bore no correlation with expression of the TRAIL receptors (DR4, DR5) or their decoys (DcR1 and DcR2), but was associated with activation of caspase‐8 and ‐3, and downregulation of the long isoform of FLICE‐like inhibitory protein (c‐FLIPL), an anti‐apoptosis mediator. Small interfering RNA‐mediated knockdown of c‐FLIPL expression restored TRAIL sensitivity in OVCA 432 cells. Induction of c‐FLIPL overexpression increased TRAIL resistance in TRAIL‐sensitive lines. Thus, persistent high level of c‐FLIPL expression likely mediates TRAIL resistance in OCa cells. Treatment of OCa cells with progesterone enhanced TRAIL‐induced cell death (>85%), but only in TRAIL‐sensitive cell lines. Combined treatment with two progestins was superior to single progestin treatment, with progesterone plus medroxyprogesterone acetate (MPA) achieving over 85% cell kill in both TRAIL‐sensitive and ‐resistant OCa cell lines. Significantly, unlike TRAIL, progestin‐induced cell death did not involve c‐FLIPL downregulation. Hence, combined progestin regimens, with or without TRAIL, may serve as an effective therapy for OCa by circumventing the anti‐apoptotic action of c‐FLIPL. J. Cell. Biochem. 102: 442–452, 2007. © 2007 Wiley‐Liss, Inc.
Two‐photon lifetime imaging of fluorescent probes in intact blood vessels: A window to sub‐cellular structural information and binding status
Authors: Douma Kim , Megens Remco T.A. , Reitsma Sietze , Prinzen Lenneke , Slaaf Dick W. , Van Zandvoort Marc A.M.J.
Published: March 2007

Fluorescence lifetime imaging (FLIM) provides a complementary contrast mechanism to fluorescence intensity and ratio imaging in intact tissue. With FLIM the time‐resolved decay in fluorescence intensity of (interacting) fluorophores can be quantified by means of time correlated single photon counting (TCSPC). Here we focus on fluorescence lifetime imaging in intact blood vessels. Requisites for imaging in intact tissue are good penetration depth and limited tissue damage. Therefore, in this pilot‐study, we performed TCSPC‐FLIM using two‐photon laser scanning microscopy to determine, with sub‐cellular resolution, the fluorescence lifetime of two fluorescent probes. First, we focused on the nucleic acid dye SYTO41 in the various compartments of cells in vitro and in situ in the wall of intact mouse carotid arteries. Second, it was assessed whether the interaction of the lectin WGA‐FITC with the endothelial glycocalyx affects its fluorescence lifetime. Results showed comparable mono‐exponential fluorescence lifetimes of SYTO41 in the nuclei of cells in vitro and in situ. The slightly shorter fluorescence lifetime observed in the cytoplasm allowed discrimination of the nuclei. SYTO41 displayed strong mitochondrial staining, as was verified by the mitochondrion‐specific probe CMXRos. In addition, mitochondrial staining by SYTO41 was accompanied by a green shift in emission. In the mitochondrial region, SYTO41 showed a highly bi‐exponential and relatively fast decay, with two distinct lifetime components. It is hypothesized that the fitted bi‐exponential decay can either be contributed to (1) the mathematical approximation of the fluorescence intensity decay or (2) the presence of free and DNA‐bound SYTO41 in the mitochondrial compartment, leading to two lifetime components. The fluorescence lifetime of WGA‐FITC decreased by ∼25% upon binding to the endothelial glycocalyx. From this study, we conclude that FLIM offers an additional contrast mechanism in imaging intact tissue and provides information on binding status between a probe and its ligand. Microsc. Res. Tech., 2007. © 2007 Wiley‐Liss, Inc.
Towards metabolic mapping of the human retina
Authors: Schweitzer D. , Schenke S. , Hammer M. , Schweitzer F. , Jentsch S. , Birckner E. , Becker W. , Bergmann A.
Published: March 2007

Functional alterations are first signs of a starting pathological process. A device that measures parameter for the characterization of the metabolism at the human eye‐ground would be a helpful tool for early diagnostics in stages when alterations are yet reversible. Measurements of blood flow and of oxygen saturation are necessary but not sufficient. The new technique of auto‐fluorescence lifetime measurement (FLIM) opens in combination with selected excitation and emission ranges the possibility for metabolic mapping. FLIM not only adds an additional discrimination parameter to distinguish different fluorophores but also resolves different quenching states of the same fluorophore. Because of its high sensitivity and high temporal resolution, its capability to resolve multi‐exponential decay functions, and its easy combination with laser scanner ophthalmoscopy, multi‐dimensional time‐correlated single photon counting was used for fundus imaging. An optimized set up for in vivo lifetime measurements at the human eye‐ground will be explained. In this, the fundus fluorescence is excited at 446 or 468 nm and the time‐resolved autofluorescence is detected in two spectral ranges between 510 and 560 nm as well as between 560 and 700 nm simultaneously. Exciting the fundus at 446 nm, several fluorescence maxima of lifetime t1 were detected between 100 and 220 ps in lifetime histograms of 40° fundus images. In contrast, excitation at 468 nm results in a single maximum of lifetime t1 = 190 ± 16 ps. Several fundus layers contribute to the fluorescence intensity in the short‐wave emission range 510–560 nm. In contrast, the fluorescence intensity in the long‐wave emission range between 560 and 700 nm is dominated by the fluorescence of lipofuscin in the retinal pigment epithelium. Comparing the lateral distribution of parameters of a tri‐exponential model function in lifetime images of the fundus with the layered anatomical fundus structure, the shortest component (t1 = 190 ps) originates from the retinal pigment epithelium and the second lifetime (t2 = 1,000 ps) from the neural retina. The lifetime t3 ≈ 5.5 ns might be influenced by the long decay of the fluorescence in the crystalline lens. In vitro analysis of the spectral properties of expected fluorophores under the condition of the living eye lightens the interpretation of in vivo measurements. Taking into account the transmission of the ocular media, the excitation of NADH is unlikely at the fundus. Microsc. Res. Tech., 2007. © 2007 Wiley‐Liss, Inc.
Simultaneous two‐photon fluorescence correlation spectroscopy and lifetime imaging of dye molecules in submicrometer fluidic structures
Authors: Petrášek Zdeněk , Krishnan Madhavi , Mönch Ingolf , Schwille Petra
Published: March 2007

Fluorescence correlation spectroscopy (FCS) is a very sensitive technique that can be used, e.g., for the measurement of low concentrations and for the investigation of transport of fluorescent molecules. Fluorescence lifetime imaging (FLIM) provides spatially resolved information about molecular fluorescence lifetimes reflecting the interactions of the molecules with their environment. We have applied simultaneous two‐photon FCS and FLIM to probe the behavior of fluorescent molecules diffusing in submicrometer silicon oxide channels. Our measurements reveal differences in fluorescence lifetimes compared to bulk solution that result from the effects of confinement and the presence of interfaces. Confinement also affects diffusional characteristics of fluorophores as reflected in fluorescence autocorrelation functions. These possible consequences of both spatial confinement and the presence of interfaces between media with different refractive indices on the diffusion and fluorescence lifetime of molecules in nanostructures are discussed in general. Microsc. Res. Tech., 2007. © 2007 Wiley‐Liss, Inc.
Fluorescence detection with high time resolution: From optical microscopy to simultaneous force and fluorescence spectroscopy
Authors: Gaiduk Alexander , Kühnemuth Ralf , Felekyan Suren , Antonik Matthew , Becker Wolfgang , Kudryavtsev Volodymyr , Sandhagen Carl , Seidel Claus A.M.
Published: March 2007

Picosecond time‐resolution fluorescence signal detection over many hours is possible using the time‐correlated single photon counting (TCSPC) technique. Advanced TCSPC with clock oscillator set by the pulsed laser and data analysis provides a tool to investigate processes in single molecules on time scale from picoseconds to seconds. Optical imaging techniques combined with TCSPC allow one to study the spatial distribution of fluorescence properties in solution and on a surface. Mechanical manipulation of a single macromolecule by means of an atomic‐force microscope makes it possible to detect fluorescence signal changes as a function of mechanical conformations of a fluorescent dye attached to a single DNA molecule. Microsc. Res. Tech., 2007. © 2007 Wiley‐Liss, Inc.
Multi‐dimensional fluorescence lifetime and FRET measurements
Authors: Biskup Christoph , Zimmer Thomas , Kelbauskas Laimonas , Hoffmann Birgit , Klöcker Nikolaj , Becker Wolfgang , Bergmann Axel , Benndorf Klaus
Published: March 2007

When and where proteins associate with each other in living cells are key questions in many biological research projects. One way to address these questions is to measure the extent of Förster resonance energy transfer (FRET) between proteins that have been labeled with appropriate donor and acceptor fluorophores. When both proteins interact, donor and acceptor fluorophores are brought into close vicinity so that the donor can transmit a part of its excitation energy to the acceptor. As a result, both the intensity and the lifetime of the donor fluorescence decrease, whereas the intensity of the acceptor emission increases. This offers different approaches to determine FRET efficiency: One is to detect changes in the intensity of donor and acceptor emission, the other is to measure changes in the lifetime of the donor molecule. One important advantage of the fluorescence lifetime approach is that it allows to distinguish between free and associated donor molecules. However, like intensity measurements it lacks an intrinsic control ensuring that changes in the measured parameters are only due to FRET and not other quenching processes. Here, we show how this limitation can be overcome by spectrally resolved fluorescence lifetime measurements in the time domain. One technique is based on a streak camera system, the other technique is based on a time‐correlated‐single‐photon‐counting approach. Both approaches allow biologists to record both donor and acceptor fluorescence emitted by the sample in a single measurement. Microsc. Res. Tech., 2007. © 2007 Wiley‐Liss, Inc.
Large‐scale, Uniform DNA Network on 11‐mercaptoundecanoic Acid Modified Gold (111) Surface: Atomic Force Microscopy Study
Authors: Song Yonghai , Wang Li , Sun Lanlan , Wei Gang , LIU ZHIGUO , Wang Li , Li Zhuang
Published: March 2007

Large‐scale, uniform plasmid deoxyribonucleic acid (DNA) network has been successfully constructed on 11‐mercaptoundecanoic acid modified gold (111) surface using a self‐assembly technique. The effect of DNA concentration on the characteristics of the DNA network was investigated by atomic force microscopy. It was found that the size of meshes and the height of fibers in the DNA network could be controlled by varying the concentration of DNA with a constant time of assembly of 24 h. Microsc. Res. Tech., 2007. © 2007 Wiley‐Liss, Inc.
Clinical two‐photon microendoscopy
Authors: König K. , Ehlers A. , Riemann I. , Schenkl S. , Bückle R. , Kaatz M.
Published: March 2007

Two‐photon medical imaging has found its way into dermatology as an excellent method for noninvasive skin cancer detection without need of contrast agents as well as for in situ drug screening of topically‐applied cosmetical and pharmaceutical components. There is an increasing demand to apply the multiphoton technology also for deep‐tissue skin imaging as well as for intracorporal imaging. We report on the first clinical use of multiphoton endoscopes, in particular of a miniaturized rigid two‐photon GRIN lens endoscope. The microendoscope was attached to the multiphoton tomograph DermaInspect and employed to detect the extracellular matrix proteins collagen and elastin in the human dermis of volunteers and patients with ulcera by in vivo second harmonic generation and in vivo two‐photon autofluorescence. Microsc. Res. Tech., 2007. © 2007 Wiley‐Liss, Inc.
Localization of Fatty Acids with Selective Chain Length by Imaging Time‐of‐Flight Secondary Ion Mass Spectrometry
Authors: Richter Katrin , Nygren Håkan , Malmberg Per , Hagenhoff Birgit
Published: March 2007

Localization of fatty acids in biological tissues was made by using TOF‐SIMS (time‐of‐flight secondary ion mass spectrometry). Two cell‐types with a specific fatty acid distribution are shown. In rat cerebellum, different distribution patterns of stearic acid (C18:0), palmitic acid (C16:0), and oleic acid (C18:1) were found. Stearic acid signals were observed accumulated in Purkinje cells with high intensities inside the cell, but not in the nucleus region. The signals colocalized with high intensity signals of the phosphocholine head group, indicating origin from phosphatidylcholine or sphingomyelin. In mouse intestine, high palmitic acid signals were found in the secretory crypt cells together with high levels of phosphorylinositol colocalized in the crypt region. Palmitic acid was also seen in the intestinal lumen that contains high amounts of mucine, which is known to be produced in the crypt cells. Linoleic acid signals (C18:2) were low in the crypt region and high in the villus region. Oleic acid signals were seen in the villi and stearic acid signals were ubiquitous with no specific localization in the intestine. We conclude that the results obtained by using imaging TOF‐SIMS are consistent with known brain and intestine biochemistry and that the localization of fatty acids is specific in differentiated cells. Microsc. Res. Tech., 2007. © 2007 Wiley‐Liss, Inc.
Comparative observations on the cyst shells of seven Artemia strains from China
Authors: Wang Sufeng , Sun Shichun
Published: March 2007

The quiescent Artemia cysts of seven geographical origins in China were examined with scanning and transmission electron microscopes. SEM observations on cysts of these Artemia strains showed that the surface topography of cyst shells could be categorized into 6 types: complete smooth surface; smooth surface with sparsely distributed glabrate humps; surface with densely arranged wart‐like humps that are composed of packed minute tubercles; rugged surface, with densely arranged tubercles not piling up to form larger humps; shallow‐pocked surface; and surface with numerous and densely spaced pore‐like fossulae. Some of the patterns were strain specific [e.g., cysts from Ga Hai (GH) are characterized by having a surface with wart‐like ornaments that are composed of packed minute tubercles, rugged surface is only found in Chengkou (CK) cysts], and apparent intrastrain variation of cyst surface topography was found in Xizang (XZ), Jingyu Hu, and Xie Chi (SIN) strains. TEM studies on the ultrastructure of cyst shells revealed an apparent divergence in the structure of outer cuticular membrane (OCM) among Artemia strains. In CK, Aqqikkol Hu (AQK), SIN, and GH strains, it is a normal, asymmetrical, and multi‐layered structure similar to those described in previous works. In XZ, JYH, and Lagkor Co (LGC) strains, however, the OCM is not obviously multi‐layered and the borderlines between OCM and adjacent layers seem indistinct. The present results suggest that the diversity of the surface topography of Artemia cysts may be an available tool for identifying certain Artemia strains as well as for tracking the origins of some Artemia cysts, and the hypoplastic OCM may be a characteristic of the species A. tibetiana. Microsc. Res. Tech., 2007. © 2007 Wiley‐Liss, Inc.
Immunohistochemical localization of angiotensin II receptor types 1 and 2 in the mesenteric artery from spontaneously hypertensive rats
Authors: Diniz Carmen , Leal Sandra , Logan Karen , Rocha‐Pereira Carolina , Soares Ana Sofia , Rocha Eduardo , Gonçalves Jorge , Fresco Paula
Published: March 2007

Angiotensin II plays a crucial role in the control of blood pressure, acting at AT1or AT2receptors, and can act as a potent vasoconstrictor of the peripheral vasculature inducing hypertrophy, hyperplasia, or both, in resistance arteries. The aim of the present study was to investigate whether the pattern of distribution of angiotensin AT1and AT2receptors on mesenteric artery sections differs in spontaneously hypertensive rats (SHR) versus their respective controls (Wistar–Kyoto [WKY] rats). Immunohistochemistry using anti‐AT1or anti‐AT2antibodies was performed on perfused‐fixed/paraffin‐embedded mesenteric arteries from SHR and WKY rats. 3,3′‐Diaminobenzidine tetrahydrochloride (DAB; activated by hydrogen peroxide) staining revealed distinct AT1and AT2labeling of all artery layers (adventitia, media and intima) from WKY rats, whereas in SHR an abundant AT1labeling was found in both intima and adventitia and a sparser labeling in the media. There was a vast reduction of AT2labeling throughout all layers. These results suggest a crucial role for AT2receptors in the pathogenesis of hypertension. Microsc. Res. Tech., 2007. © 2007 Wiley‐Liss, Inc.
Predominance of supraspinal innervation of the left ovary
Authors: Tóth Ida E. , Wiesel Ory , BoldogkőI Zsolt , Bálint Kamill , Tapaszti Zsuzsa , Gerendai Ida
Published: March 2007

In our previous studies using the viral transneuronal tracing technique we demonstrated the spinal and supraspinal components of the ovarian innervation. Since increasing number of data indicate the presence of morphological and functional laterality in the control of gonadal functions, we aimed to investigate whether cerebral structures trans‐synaptically involved in the innervation of the ovary exhibit asymmetry or not. In one of the studies the left or the right ovary was injected with the red fluorescent protein expressing pseudorabies virus and the number of infected “red” autofluorescent neurons from the right and the left ovary was compared. In another study in order to have distinct labeling of cell groups connected with the right‐ and left‐sided ovary in the same animal, a dual viral labeling was applied. The left‐ and right‐sided ovary were inoculated with genetically engineered pseudorabies virus expressing a red fluorescent protein or a green fluorescent protein gene. Viral infection of brain nuclei including the dorsal vagal nucleus, caudal raphe nuclei, A5 noradrenergic cell group, hypothalamic paraventricular nucleus, from the left ovary in each case was enhanced when compared with labeling from the right gonad. Data suggest a predominance in the supraspinal innervation of the left ovary. Microsc. Res. Tech., 2007. © 2007 Wiley‐Liss, Inc.
Identification of starch grains in microscopic images based on granulometric operations
Authors: Tong Chong‐Sze , Choy Siu‐Kai , Zhao Zhong‐Zhen , Liang Zhi‐Tao , Chen Hubiao
Published: March 2007

This study demonstrates the feasibility of feature extraction and similarity measurement for the identification of starch grains, which are often found in microscopic images of Chinese Materia Medica (CMM) and as such is an important feature for use in the authentication of CMM with abundance of starch grains and otherwise without other special microscopic characteristics. Our proposed image signature, namely, the size distribution, indicates that it is effective to characterize starch grains in microscopic images of those CMM. Experimental results in a small scale study show that the recognition rate for the proposed signature using different measures of discrepancy is around 90%, which is considered very good while the benchmark wavelet‐based energy signature has only about 60% recognition. Moreover, the extraction of the size distribution only requires moderate level of computational complexity. In this study, our proposed image signature provides greater accuracy and flexibility in capturing starch grains information for the authentication of CMM, compared with other existing preliminary identification approach in which manual image segmentation is necessary. Microsc. Res. Tech., 2007. © 2007 Wiley‐Liss, Inc.
New method for the treatment of sperm samples for ultrastructural study based on the use of animal tissues as biological containers
Authors: Junquera Concepción , Colás Carmen , Martínez‐Ciriano Carmen , Serrano Pedro , Castiella Tomás , Cebrian‐Perez José A. , Muiño‐Blanco Teresa
Published: March 2007

The study of the ultrastructure of spematozoa by means of transmission electron microscopy (TEM) often presents with problems of interpretation according to the method employed, depending on whether samples are either centrifuged previously to the fixation or immersed in viscous gels. The major problems of interpretation are changes in the location of vesicles originated during the maturation process and modifications in the adsorption of seminal plasma proteins to the sperm membrane surface. The aim of our study is to communicate an original new method for the treatment of spermatozoa for ultrastructural study. Our method is based on the use of animal tissues as biological containers, inside which the spermatic suspensions are included. We developed this method using fresh sperm samples taken from mature Rasa Aragonesa rams. As biological container, we used 2.5‐cm long segments of the intestine of 1‐week‐old chickens (Gallus gallus) (diameter around 4 mm). In order to avoid any influence of digestive enzymes of the mucosa on the sperm surface, we put each intestine fragment inside out by means of microdissection forceps under a bifocal optical microscope and cold light. One of the edges was tied with thin suture silk. The sperm suspension was injected in the optimal experimental condition and amount. Finally, the still‐open edge of the intestine segment was tied with silk in the same way as the other segment edge. By using this technique, we can perform a suitable morphological study at an ultrastructural level. In addition, the functional relationship of the ultrastructural components of the target cells is correctly preserved. Microsc. Res. Tech., 2007. © 2007 Wiley‐Liss, Inc.
Promises of transformation: just how different are international development NGOs?
Authors: Mowles Chris
Published: March 2007

This article argues that there is a growing convergence between development INGOs and private sector organisations in the way that values are taken up as an instrument of management. Rather than promoting the exploration of difference, managers encourage employees to set aside their concerns and have faith in the organisational mission. In this way they exercise control without appearing to do so, and avoid dealing with the day to day difficulty of undertaking the work. Instead managers feel obliged to promise transformation, because of the increased marketisation and professionalisation of development. The article offers an alternative understanding of values as a profoundly social phenomenon requiring reflection and negotiation through and with others. Copyright © 2007 John Wiley & Sons, Ltd.
Impartiality through bureaucracy? A Sri Lankan approach to managing values
Authors: McCourt Willy
Published: March 2007

This article starts from a crux in Alan Thomas's model of development management: that values‐based development management may require the coercion of employees whose values are different. It uses a case study of Sri Lanka's attempt to inculcate the value of impartiality in staffing, focusing on the restoration of the independence of the Service Commissions. The article concludes that values‐based management is likeliest to succeed in the public sector, whose democratic legitimacy allows politicians to impose values in the form of behavioural norms. Ironically, such management is more complicated in the NGO sector, whose uncertain legitimacy means that managers must negotiate values with staff who may have competing values of their own. Copyright © 2007 John Wiley & Sons, Ltd.
The role of contestation in NGO partnerships
Authors: Harrison Tom
Published: March 2007

In this article I use a case study of the relationship between an international non‐government development organisation (NGO) and one of its local partner NGOs to question the desirability of basing NGO partnerships on the principle of subsidiarity. I argue that devolving maximum control to the local NGO in accordance with the principle of subsidiarity would have conflicted with the interests and expectations of both the international NGO and its local partner. As a result, there was occasional but significant contestation between these organisations about what sort of relationship was most compatible with the principle of partnership and what role each party should play within that relationship. I argue that such contestation over what constitutes partnership has the potential to contribute to the realisation of this value‐laden term by involving all parties in defining the nature of their relationship. Copyright © 2007 John Wiley & Sons, Ltd.
Steering across scales: applying a strategic‐relational approach to a study of land mobilisation for road widening in Kochi
Authors: Chettiparamb Angelique
Published: March 2007

This paper argues for the relevance of paying attention to structuring participation processes across scales as one of the ways in which participation of multi‐organisational partnerships that involve conflicting interests might be managed. Issue wise the paper deals with problems in connection with land mobilisation for road widening in complex and concentrated high value urban settings. It discusses a case study of plan implementation involving individual landowners, the land development market, the local government, other governmental and non‐governmental organisations and the state government, which together achieved objectives that seemed impossible at first sight. In theoretical terms, the paper engages with Jessop's (2001) Strategic‐Relational Approach (SRA), arguing for its potential for informing action in a way that is capable of achieving steering outputs. The claim for SRA is demonstrated by re‐examining the case study. The factors that come through as SRA is applied are drawn out and it is suggested that the theory though non‐deterministic, helps guide action by highlighting certain dynamics of systems that can be used for institutional intervention. These dynamics point to the importance of paying attention to scale and the way in which participation and negotiation processes are structured so as to favour certain outcomes rather than others. Copyright © 2007 John Wiley & Sons, Ltd.
Primary afferent dendrite degeneration as a cause of tinnitus
Authors: Bauer Carol A. , Brozoski Thomas J. , Myers Kristin
Published: March 2007

Chronic tinnitus affects millions of people, but the mechanisms responsible for the development of this abnormal sensory state remain poorly understood. This study examined the type and extent of cochlear damage that occurs after acoustic trauma sufficient to induce chronic tinnitus in rats. Tinnitus was evaluated by using a conditioned suppression method of behavioral testing. Cochlear damage was assessed 6 months after acoustic trauma. There was minimal loss of inner and outer hair cells in the exposed cochleas of subjects demonstrating evidence of tinnitus. However, a significant loss of large‐diameter fibers in the osseous spiral lamina of exposed cochleas of trauma subjects was observed. The significance of this finding in the context of a model of tinnitus is discussed. © 2007 Wiley‐Liss, Inc.
On the reliability of 13C metabolic modeling with two‐compartment neuronal‐glial models
Authors: Shestov Alexander A. , Valette Julien , Uğurbil Kâmil , Henry Pierre‐Gilles
Published: March 2007

Metabolic modeling of 13C NMR spectroscopy (13C MRS) data using two‐compartment neuronal‐glial models enabled non‐invasive measurements of the glutamate‐glutamine cycle rate (VNT) in the brain in vivo. However, the reliability of such two‐compartment metabolic modeling has not been examined thoroughly. This study uses Monte‐Carlo simulations to investigate the reliability of metabolic modeling of 13C positional enrichment time courses measured in brain amino acids such as glutamate and glutamine during [1‐13C]‐ or [1,6‐13C2]glucose infusion. Results show that the determination of VNT is not very precise under experimental conditions typical of in vivo NMR studies, whereas the neuronal TCA cycle rate VTCA(N) is determined with a much higher precision. Consistent with these results, simulated 13C positional enrichment curves for glutamate and glutamine are much more sensitive to the value of VTCA(N) than to the value of VNT. We conclude that the determination of the glutamate‐glutamine cycle rate VNT using 13C MRS is relatively unreliable when fitting 13C positional enrichment curves obtained during [1‐13C] or [1,6‐13C2]glucose infusion. Further developments are needed to improve the determination of VNT, for example using additional information from 13C‐13C isotopomers and/or using glial specific substrates such as [2‐13C]acetate. © 2007 Wiley‐Liss, Inc.
p‐Type Semiconducting Dendrimers Bearing Thiophenyl Peripheral Moieties: Effect of Alkyl Chains on Molecular Packing Geometry
Authors: Kim Kyung Hwan , Chi Zhenguo , Cho Min Ju , Jin Jung‐Il , Choi Dong Hoon , Paek Sang Hyon
Published: March 2007

First generation thiophene‐labeled conjugated dendrimers have been synthesized through the Heck coupling reaction between the 5‐vinyl‐[2,2′]bithio‐ phenyl derivative and 1,2,4,5‐tetrabromo‐benzene as a core. One dendrimer has hexyl groups at the periphery and the other does not have it. They display a considerably better solubility than the linear conjugated oligothiophene. We observe drastic spectral change in a film state of dendrimer due to crystallization and a high extent of intermolecular interaction. Effect of peripheral alkyl groups on the intermolecular interaction and lamella orderness was investigated using two dendrimers.
Ultrathin Ferroelectric P(VDF/TrFE) Copolymer Film in Low‐Cost Non‐Volatile Data Storage Applications
Authors: Lee Jong Soon , Prabu A. Anand , Chang You Min , Kim Kap Jin
Published: March 2007

Ultrathin ferroelectric P(VDF/TrFE(72/28) films were used in the fabrication of metal‐ferroelectric polymer‐metal single bit device with special emphasis on the formation of uniform film surface, faster dipole switching time under an external electric field, and longer memory retention time. FTIR‐GIRAS and AFM were used complementarily in analyzing the changes in chain orientation and surface crystalline morphology with varying sample preparation methods. It was found that the magnitudes of remnant polarization and coercive field are highly related to the degree of chain orientation along the conductive substrate surface. The cast‐ annealed sample showed the highest polarization and the smallest coercive field. DC‐EFM technique was successfully used to ‘write and erase’ the data bit on the ultrathin P(VDF/TrFE) film by applying a dc bias voltage much larger than coercive voltage with different polarities and the data bit state could be read by measuring the piezoelectric response of the cantilever with a lock‐in amplifier by applying an ac modulating voltage whose Vpp is much less than the coercive voltage.
Thermally Stable Photo‐Crosslinking Polymers Bearing Cinnamate Groups for Liquid Crystal Alignment
Authors: Sung Oh Hyun , Cho Seung Hyun , Kim Whan Gun , Song Ki Gook , Paek Sang Hyon , Lee Jun Young
Published: March 2007

Optically ansiotropic photo‐crosslinking polymers were synthesized through reaction between different kinds of epoxy resins and cinnamic acids. Optical anisotropy of the polymer film exposed to linearly polarized UV light (LPUVL) was confirmed from the polarized UV‐Visible spectra. The polymer films irradiated by LPUVL showed anisotropic absorbance in the polarized UV‐Visible spectra, while the polymer irradiated by unpolarized UV exhibited isotropic absorbance. It was also confirmed that the polymer film exposed to LPUVL could align liquid crystals (LC). LC cell fabricated using the polymer films irradiated by LPUVL showed the anisotropic polar diagram, implying that the polymer films may be applied as the photoalignment layer for LC display.
Solid State Photoluminescence Property of a Novel POSS‐Based Material Having Carbazole
Authors: Imae Ichiro , Kawakami Yusuke , Ooyama Yousuke , Harima Yutaka
Published: March 2007

Octakis[2‐carbazol‐9‐yl]ethyldimethylsiloxy]silsesquioxane (POSS‐Cz) was newly synthesized and its photoluminescence properties in both solution and solid states were investigated. POSS‐Cz showed monomeric emission peak not only in solution state but also in solid state. This result suggests that the introduction of octasilsesquioxane core will suppress the aggregation of carbazole even in solid state.
Cyclodextrin‐Induced Fluorescence Enhancement of an Ionic Polyacetylene Having Phenylethylpyridinium Groups
Authors: Lee Sang‐Mi , Lee Ji‐Seok , Kim Jong‐Man
Published: March 2007

A phenylethylpyridinium substituted polyacetylene PA‐PEP has been prepared in a straight forward manner by the reaction of 2‐ethylnylpyridine with (2‐bromoethyl)benzene. The UV‐visible maximum of this ionic polyacetylene undergoes a bathochromic shift in the presence of β‐cyclodextrin. In contrast, a negligible bathochromic shift is observed in the presence of α‐ or γ‐cyclodextrin. In addition, the most prominent enhancement fluorescence intensity of the polyacetylene was observed with β‐cyclodextrin when it interacts with cyclodextrins. It is proposed that the observed fluorescence perturbations are a consequence of the inclusion complex formed between β‐cyclodextrin and the polyacetylene side‐chain.
Preparation of a Sensing Membrane for C‐Reactive Protein
Authors: Kim Huyn‐Chul , Lee Soo‐Keun , Sohn Young‐Soo , Ryu Hong‐Kun , Jeong Sang Won
Published: March 2007

11,11′‐dithiobis(undecanyl succinate) (DS11SACOOH) was synthesized to develop a new surface for immobilization of proteins or antibodies on a gold substrate. DS11SACOOH is a bifunctional linker that has a disulfide group to form SAM (self‐assembled monolayer) on a gold substrate and two carboxylic moieties for reaction with biomolecules such as peptide, DNA, etc. After preparation of SAM on a gold‐coated quartz cell with DS11SACOOH, the SAM surface was activated with NHS (N‐hydroxysuccimide). The terminal NHS ester was reacted with anti‐CRP (C‐reactive protein). The binding behavior of CRP on the surface was monitored by use of SPR (surface plasmon resonance) sensor system.
Preparation and Characterization of Bone Cements Incorporated with Montmorillonite
Authors: Kwon Soon Yong , Kim Sung Soo
Published: March 2007

Bone cements incorporated with montmorillonite (MMT) were prepared in an attempt to improve their mechanical properties. The cements were characterized using particle size analysis, gel permeation chromatography, viscosity measurements, unreacted monomer analysis, X‐ray diffraction, transmission electron microscopy, energy‐dispersive X‐ray spectroscopy, and mechanical properties. The average particle size and molecular weight of the PMMA powders used were 47 µm and 100,000 g/mol, respectively. The incorporation of MMT led to an increase in viscosity of the bone cement but did not severely affect its setting temperature or the amount of residual monomer. Regardless of the MMT mixing methods used, in this case MMT being mixing in liquid and powder components, sodium MMT (SMMT) was not well dispersed in the bone cements, which was believed to be due to its hydrophilicity. Organophilic MMT (OMMT) was better dispersed in the liquid component than in the powder component. The compressive and tensile strength of the bone cement containing the OMMT mixed into the liquid component were significantly higher than those of the bone cement without MMT (p < 0.05).
Surface Characteristics of Plasma‐Treated PLGA Nanofibers
Authors: Park Ko Eun , Lee Kuen Yong , Lee Seung Jin , Park Won Ho
Published: March 2007

PLGA nanofibers were prepared by an electrospinning method (mean diameter, 340 nm) and treated with plasma in the presence of either oxygen or ammonia gas to modify the surface of the nanofibers. The surface hydrophilicity of electrospun PLGA nanofibers was greatly increased by plasma treatment, which was confirmed by contact angle measurement. XPS analysis demonstrates that the number of polar groups on the surface of PLGA nanofibers after plasma treatment was increased, and this was considered to contribute to the enhanced surface hydrophilicity of the nanofibers. This approach to controlling the surface properties and structures of nanofibers could be useful in the design and tailoring of novel synthetic extracellular matrices for tissue engineering applications.
Anticancer Drug‐Phospholipid Conjugate for Enhancement of Intracellular Drug Delivery
Authors: Hwang Taewon , Han Hee Dong , Song Chung Kil , Seong Hasoo , Kim Jung Hyun , Chen Xiaoyuan , Shin Byung Cheol
Published: March 2007

Tumor specific delivery of anti‐cancer drugs is one of the major challenges faced by drug development processes. In this study, we prepared a doxorubicin (DOX)‐conjugated liposome (DCL) by incorporating the newly synthesized DSPE‐PEG2000‐DOX (DPD) into liposomes as a lipid component and tested its anti‐tumor activity in vivo. DPD was synthesized by coupling DOX to DSPE‐PEG2000‐COOH via amide linkage and the chemical structure of resulting DPD was confirmed by 1H‐NMR analysis. DCL having liposome size of 130 nm was prepared through thin film cast‐hydration method. DCL was found to have significantly higher cellular uptake than conventional liposomes as confirmed by flow cytometry analysis. Anti‐tumor activity of DCL against murine B16F10 melanoma tumor‐bearing mice revealed that DCL inhibits tumor growth more efficiently than the conventional liposomes, presumably attributed to DOX mediated endocytosis process.
New Sol‐Gel Transition Hydrogels Based on Pluronic‐Mimicking Copolymers Grafted with Oligo(lactic acids)
Authors: Lee Yuhan , Park Sung Young , Chung Hyun Jung , Park Tae Gwan
Published: March 2007

A novel type of poly(ethylene oxide)‐poly(propylene oxide)‐poly(ethylene oxide) (PEO‐PPO‐PEO) triblock copolymers grafted with oligo(D,L‐lactic acid) (OLA) on the middle PPO segment was synthesized. The Pluronic‐mimicking copolymers exhibited gel‐to‐sol transitions with increasing temperature over a wide range of copolymer concentrations, and formed more stable hydrogel structures than Pluronic F127 copolymer in aqueous solution. The gel‐to‐sol phase transition temperature was controllable depending on chain length of the grafted OLA on the PPO chain. The gel‐to‐sol transition occurring with raising temperature was attributed to thermal destabilization and expansion of the inner hydrophobic core, which disturbed the packing order of spherical micelles required for physical gelation. The OLA grafted Pluronic mimicking hydrogels not only showed highly retarded erosion at 37 °C but also sustained protein release profiles, compared to Pluronic F127 hydrogel.
Receptor‐Mediated Gene Delivery Using Chitosan Derivatives in Vitro and in Vivo
Authors: Kim Tae‐Hee , Jiang Hu‐Lin , Nah Jae‐Woon , Cho Myung‐Haing , Akaike Toshihiro , Cho Chong‐Su
Published: March 2007

The development of an efficient targeted gene delivery system into cells is an important strategy for the advancement of gene therapy. The targeted gene delivery system is especially important in non‐viral gene transfer which shows the relative low transfection efficiency. And it also opens the possibility of selective delivery of therapeutic plasmids to specific tissues. Chitosan has been investigated as a non‐viral vector because it has several advantages such as biocompatibility, biodegradability and low toxicity with high cationic potential. However, low specificity and low transfection efficiency of chitosan need to be overcome prior to clinical trial. In this review, we focused on the specific ligand modification of chitosan for enhancement of cell specificity and transfection efficiency via receptor‐mediated endocytosis in vitro and in vivo.
Preparation of Biodegradable Polymer Scaffolds with Dual Pore System for Tissue Regeneration
Authors: Park Kwideok , Jung Hyun Jung , Son Jun Sik , Park Ki Dong , Kim Jae‐Jin , Ahn Kwang‐Duk , Han Dong Keun
Published: March 2007

Biodegradable polymer scaffolds that have dual pores on the matrix were successfully prepared using a combination of gas foaming and phase separation methods. PLLA and PLGA were dissolved in dioxane/water at the ratios of 90/10, 87/13, or 85/15 (v/v), respectively. Sodium bicarbonate was then added to the polymer solution and freezed‐dried, then subjected to a gas foaming process. Dual pore scaffolds have two distinct pore sizes: large pores in 200∼300 µm and small ones in 5∼20 µm, with the interconnected structure. Their porosities were ranged from 92 to 98%, significantly higher than those of unipore scaffold (90%). Two variables, water content (10, 13, and 15%) and freeze‐drying temperature (FDT; −196, −70, and −20 °C), were introduced during the scaffold preparation. Mechanical compressive strength decreased as the polymer solution was gradually diluted with water (100/0 to 85/15, v/v). Earlier weight loss of the different scaffolds was found with FDT at −20 °C but the final result was the same, regardless of different FDTs used. These dual pore polymer scaffolds may thus be useful in tissue engineering applications.
Dye Sensitized Solar Cell Using Polymer Electrolytes Based on Poly(ethylene oxide) with an Ionic Liquid
Authors: Singh Pramod K. , Kim Ki‐Il , Park Nam‐Gyu , Rhee Hee‐Woo
Published: March 2007

Polymer electrolytes were prepared by doping PEO:KI/I2 with an ionic liquid (IL) 1‐ethyl 3‐methylimidazolium thiocyanate (EMImSCN). FTIR confirmed composite nature while X‐ray diffraction (XRD) measurement affirmed the reduction in crystallinity, when IL was added. The ionic conductivity was improved by the addition of IL. The photoelectrochemical effect of the IL–doping in the terms of the current density Jsc and efficiency of a dye sensitized solar cells (DSSC) has also been discussed.
Development of Solid‐State Alkaline Electrolytes for Solid Alkaline Fuel Cells
Authors: Park Jin‐Soo , Park Gu‐Gon , Park Seok‐Hee , Yoon Young‐Gi , Kim Chang Soo , Lee Won Yong
Published: March 2007

Solid‐state alkaline electrolytes were prepared from chloromethylated polysuflone (CMPSf) and a number of mono‐ and diamine compounds for solid alkaline fuel cell (SAFC) applications. Chloromethyl‐groups as substituents for aromatic nuclei were introduced to an aromatic polymer in the presence of a Friedel‐Crafts catalyst and then the basic groups into polymer by amination using N‐trimethylamine (TMA) and N,N,N′,N′‐tetraemethylhexanediamine (TMHDA). The properties of the solid‐state alkaline electrolytes were invetigated in terms of OH– conductivity, water content and thermal stability.
PMMA Encapsulated Silica Particles by Dispersion Polymerization in Supercritical Carbon Dioxide
Authors: Park Eun Ju , Kim Won Soo , Hwang Ha Soo , Park Chan , Lim Kwon Taek
Published: March 2007

PMMA encapsulated silica particles were synthesized by the dispersion polymerization of MMA in supercritical carbon dioxide (scCO2). Nanosized silica particles pretreated with 3‐(trimethoxysilyl) propyl methacrylate (γ‐MPS) were used as seeds in the polymerization. Polymeric stabilizer, poly(dimethylsiloxane)‐b‐poly (methacrylic acid) (PDMS‐b‐PMA) copolymer provided sufficient stabilization to the silica/PMMA composite latexes in scCO2 to produce spherical particles. SEM and TEM analysis revealed that the composite particles have core‐shell type morphology.
In‐situ Crosslinked Polymer Electrolyte Membranes from Thermally Reactive Oligomers for Direct Methanol Fuel Cells
Authors: Park Sam Dae , Chang Yoon Ju , Jung Jin Chul , Lee Wonmok , Chang H. , Kim Haekyoung
Published: March 2007

Thermally reactive ally‐terminated sulfonated oligosulfone was easily synthesized and made it possible to fabricate crosslinked membrane with high ionic group contents for direct methanol fuel cells. The crosslinked network structures of rigid rod sulfonated polyarylene sulfone showed high suppression of swelling with high sulfonation degree of 70%, which gave excellent properties for direct methanol fuel cell applications. The proposed membranes gave unprecedented reduction in methanol cross‐over (less than 3% of Nafion 112) and high ionic conductivity (∼80% of Nafion 112).
Conductivity Behaviour of Nanocomposite Polymer Electrolytes: Role of Fumed Silica and Plasticizer
Authors: Sekhon S. S. , Sharma J. P. , Park J. S.
Published: March 2007

Polymer electrolytes obtained by the complexation of ammonium bifluoride (NH4HF2) with polyethylene oxide (PEO) have been studied. The addition of propylene carbonate (PC) results in conductivity enhancement by two orders of magnitude and shows conductivity of 1.4 × 10−4 S/cm at 25 °C, whereas the addition of fumed silica results in conductivity enhancement and show conductivity of 1.19 × 10−5 S/cm at 25 °C. However simultaneous addition of plasticizer (PC) and fumed silica to polymer electrolytes has been found to result in higher conductivity of 1.55 × 10−4 S/cm at 25 °C alongwith better mechanical properties. The complexation of NH4HF2 with PEO, formation of ion aggregates and their dissociation with the addition of PC has also been studied by FTIR.
Preparation of Buckyball‐Shaped Conducting Polythiophene by the Gamma Radiation‐Induced Polymerization Method
Authors: Karim Mohammad Rezaul , Lee Chul Jae , Kim Hee Jin , Bhuiyan Md Tauhidul Islam , Lee Mu Sang
Published: March 2007

We report on a fascinating morphology; giant spherical conducting polythiophene by the in‐situ gamma radiation‐induced chemical polymerization method. The resultant micron‐size buckyball‐shaped polymer structures were identified by high resolution transmission electron microscopy and scanning electron microscopy. Different characterizations e.g. elemental analysis, Fourier transform infrared, x‐ray diffraction, and x‐ray photoelectron spectroscopy were utilized to prove that the new morphological conducting polythiophene was synthesized successfully by this novel method.
High‐K and Low Loss Bi1.5Zn1.0Nb1.5O7/Polyimide Composite Films for Application in Embedded Capacitors
Authors: Choi Seung‐Hoon , Kim Il‐Doo , Hong Jae‐Min , Oh Seong‐Guen
Published: March 2007

We report on the role of Bi1.5Zn1.0Nb1.5O7 (BZN) ceramic fillers in notably reducing the dielectric loss of BZN/polyimide composite films manufactured for application in flexible RF embedded capacitors. The composite films were synthesized using a colloidal process. INAAT (isopropyl tris(N‐amino‐ethyl aminoethyl)titanate) was used as a coupling agent for homogeneous dispersion of BZN particles into a polyimide matrix. The BZN/polyimide composite films (BZN content at 50 Vol%) exhibited a low dielectric loss of 0.0369 at 12 MHz while retaining a high dielectric constant of 14.75.