bluuebunny/crossref_metadata_2025 huggingface dataset:
A taxonomy of model structures for economic evaluation of health technologies
Authors: Brennan Alan , Chick Stephen E. , Davies Ruth
Published: August 2006

Models for the economic evaluation of health technologies provide valuable information to decision makers. The choice of model structure is rarely discussed in published studies and can affect the results produced. Many papers describe good modelling practice, but few describe how to choose from the many types of available models. This paper develops a new taxonomy of model structures. The horizontal axis of the taxonomy describes assumptions about the role of expected values, randomness, the heterogeneity of entities, and the degree of non‐Markovian structure. Commonly used aggregate models, including decision trees and Markov models require large population numbers, homogeneous sub‐groups and linear interactions. Individual models are more flexible, but may require replications with different random numbers to estimate expected values. The vertical axis of the taxonomy describes potential interactions between the individual actors, as well as how the interactions occur through time. Models using interactions, such as system dynamics, some Markov models, and discrete event simulation are fairly uncommon in the health economics but are necessary for modelling infectious diseases and systems with constrained resources. The paper provides guidance for choosing a model, based on key requirements, including output requirements, the population size, and system complexity. Copyright © 2006 John Wiley & Sons, Ltd.
Minimally invasive endoscopic resection of the submandibular gland: A new approach
Authors: Chen Mu‐Kuan , Su Chin‐Chuan , Tsai Yao‐Lung , Chang Cheng‐Chaun
Published: August 2006

Background.

This study evaluates the benefits of a new approach, endoscopic resection of the submandibular gland through the hyoid midline level skin incision by use of an ultrasonically activated scalpel.

Methods.

Twelve operations for patients presenting with submandibular gland disease were performed via minimally invasive endoscopic resection by a single surgeon (M‐KC).

Results.

All 12 submandibular gland resections were successfully performed endoscopically, and no conversions to conventional open resection were necessary. Of the 12 patients who underwent excision, 3, 6, and 3 had mixed tumor, sialoadenitis with sialolithiasis, and chronic sialoadenitis, respectively. The procedures lasted 50 to 125 minutes (median duration, 70 minutes). No complications associated with the operation occurred, and the scar was almost invisible because of its concealed location with the neck in the natural position.

Conclusions.

Endoscopic resection of the submandibular gland is a feasible method for treatment of benign lesions. The main advantages of this procedure are that the small operative scar is concealed in the submental skin crease, resulting in improved cosmetic results and minimization of the possibility of facial nerve injury. © 2006 Wiley Periodicals, Inc. Head Neck, 2006
Genetic programming model for forecast of short and noisy data
Authors: Sivapragasam C. , Vincent P. , Vasudevan G.
Published: August 2006

Though forecasting of river flow has received a great deal of attention from engineers and researchers throughout the world, this still continues to be a challenging task owing to the complexity of the process. In the last decade or so, artificial neural networks (ANNs) have been widely applied, and their ability to model complex phenomena has been clearly demonstrated. However, the success of ANNs depends very crucially on having representative records of sufficient length. Further, the forecast accuracy decreases rapidly with an increase in the forecast horizon. In this study, the use of the Darwinian theory‐based recent evolutionary technique of genetic programming (GP) is suggested to forecast fortnightly flow up to 4‐lead. It is demonstrated that short lead predictions can be significantly improved from a short and noisy time series if the stochastic (noise) component is appropriately filtered out. The deterministic component can then be easily modelled. Further, only the immediate antecedent exogenous and/or non‐exogenous inputs can be assumed to control the process. With an increase in the forecast horizon, the stochastic components also play an important role in the forecast, besides the inherent difficulty in ascertaining the appropriate input variables which can be assumed to govern the underlying process. GP is found to be an efficient tool to identify the most appropriate input variables to achieve reasonable prediction accuracy for higher lead‐period forecasts. A comparison with ANNs suggests that though there is no significant difference in the prediction accuracy, GP does offer some unique advantages. Copyright © 2006 John Wiley & Sons, Ltd.
Seasonal flooding in Bangladesh – variability and predictability
Authors: Chowdhury Md. Rashed , Ward M. Neil
Published: August 2006

At present, Bangladesh has a flood forecasting lead time of only 3 days or so. There is demand for a forecasting lead time of a month to a season. The primary objectives of this paper are to study the variability and predictability of seasonal flooding in Bangladesh, as revealed by large‐scale predictors of the climate across the watersheds. To explore the source of predictability, accessible Bangladesh hydrological indicators are related to large‐scale oceanic variability and to large‐scale atmospheric circulation patterns predicted by general circulation models (GCMs).

Correlation analyses between the flood‐affected area (FAA) for July–September and tropical sea‐surface temperature (SST) indicate connections to tropical Pacific and Indian Ocean SSTs, at a short lead time of a month or so. These are related to El Niño–southern oscillation (ENSO). Correlations between the SSTs of the preceding October–December and the July–September FAA are weaker but notable. Forecasts of the FAA using the leading principal components (PCs) of SST were made, which provided good skill with a lead time of a month or so. The streamflows and rainfall observed in Bangladesh have been added to these prediction models. Finally, the SST PCs were replaced with PCs of GCM prediction fields (precipitation). The prediction models at short lead time that were constructed for FAA were of generally similar levels of skill to that for SST. This is encouraging, as it suggests that linkages with SST can be successfully recovered in a physical model of the climate system in Bangladesh.

This study concludes that seasonal flood prediction in Bangladesh is possible from the unusually warm or cold SST in parts of the tropics. This predictability can be enhanced with the information achievable from monitoring the downstream streamflows (which are generated mainly from upstream rainfall conditions) in advance of the flooding season. Finally, this study recommends formalizing a regional cooperation among the countries in the principal co‐basin areas of the Ganges–Brahmaputra–Meghna to achieve this goal. Copyright © 2006 John Wiley & Sons, Ltd.
Assessment of rainfall‐runoff models based upon wavelet analysis
Authors: Lane Stuart N.
Published: August 2006

A basic hypothesis is proposed: given that wavelet‐based analysis has been used to interpret runoff time‐series, it may be extended to evaluation of rainfall‐runoff model results. Conventional objective functions make certain assumptions about the data series to which they are applied (e.g. uncorrelated error, homoscedasticity). The difficulty that objective functions have in distinguishing between different realizations of the same model, or different models of the same system, is that they may have contributed in part to the occurrence of model equifinality. Of particular concern is the fact that the error present in a rainfall‐runoff model may be time dependent, requiring some form of time localization in both identification of error and derivation of global objective functions. We explore the use of a complex Gaussian (order 2) wavelet to describe: (1) a measured hydrograph; (2) the same hydrograph with different simulated errors introduced; and (3) model predictions of the same hydrograph based upon a modified form of TOPMODEL. The analysis of results was based upon: (a) differences in wavelet power (the wavelet power error) between the measured hydrograph and both the simulated error and modelled hydrographs; and (b) the wavelet phase. Power difference and wavelet phase were used to develop two objective functions, RMSE(power) and RMS(phase), which were shown to distinguish between simulated errors and model predictions with similar values of the commonly adopted Nash‐Sutcliffe efficiency index. These objective functions suffer because they do not retain time, frequency or time‐frequency localization. Consideration of wavelet power spectra and time‐ and frequency‐integrated power spectra shows that the impacts of different types of simulated error can be seen through retention of some localization, especially in relation to when and the scale over which error was manifest. Theoretical objections to the use of wavelet analysis for this type of application are noted, especially in relation to the dependence of findings upon the wavelet chosen. However, it is argued that the benefits of localization and the qualitatively low sensitivity of wavelet power and phase to wavelet choice are sufficient to warrant further exploration of wavelet‐based approaches to rainfall‐runoff model evaluation. Copyright © 2006 John Wiley & Sons, Ltd.
Novel “plum pudding” gels as potential drug‐eluting stent coatings: Controlled release of fluvastatin
Authors: McGillicuddy F.C. , Lynch I. , Rochev Y.A. , Burke M. , Dawson K.A. , Gallagher W.M. , Keenan A.K.
Published: August 2006

This study evaluated novel structural motifs known as “plum pudding” gels as potential drug‐eluting stent coatings. Controlled delivery of a HMG‐CoA reductase inhibitor (statin) from the intravascular stent surface represents a potential therapeutic modality for prevention of in‐stent restenosis (ISR). In this study, gels were comprised of fluvastatin‐loaded thermoresponsive microgel particles containing the relatively hydrophilic N‐isopropylacrylamide (NiPAAm), mixed with the more hydrophobic N‐tert‐butylacrylamide (NtBAAm) in different wt/wt ratios: 85/15, 65/35, and 50/50, randomly dispersed in a 65/35 or 85/15 NiPAAm/NtBAAm copolymer matrix. Fluvastatin release from 5 μm copolymer films was greatest from the most hydrophilic systems and least from the more hydrophobic systems. Release from hydrophobic matrices appeared to be via Fickian diffusion, enabling use of the Stokes–Einstein equation to determine diffusion coefficients. Release from hydrophilic matrices was non‐Fickian. Eluted drug retained its bioactivity, assessed as selective inhibition of human coronary artery smooth muscle cell proliferation. When stainless steel stent wires were coated (25 μm thickness) with fluvastatin‐loaded 65/35 microgels in an 85/15 copolymer matrix, drug elution into static and perfused flow environments followed similar elution profiles. In contrast to elution from copolymer films cast on flat surfaces, diffusion from stent wires coated with hydrophilic and hydrophobic systems both followed Fickian patterns, with slightly larger diffusion coefficients for elution from the flow system. We conclude that manipulation of the relative hydrophobicities of both microgel and matrix components of “plum pudding” gels results in tightly regulated release of fluvastatin over an extended time period relevant to initiation and propagation of ISR. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Synthesis and temperature response analysis of magnetic‐hydrogel nanocomposites
Authors: Frimpong Reynolds A. , Fraser Stew , Zach Hilt J.
Published: August 2006

Magnetically responsive hydrogel networks based on composites of magnetic nanoparticles and temperature responsive hydrogels were developed. These systems show great promise as active components of microscale and nanoscale devices and are expected to have a wide applicability in various biomedical applications. Specifically, nanocomposite hydrogel systems based on the temperature sensitive N‐isopropylacrylamide hydrogels crosslinked with ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, and poly(ethylene glycol) 400 dimethacrylate (PEG400DMA) were synthesized and characterized. The composite systems were synthesized by UV free‐radical polymerization. Iron oxide magnetic nanoparticles were incorporated into the hydrogel systems by polymerizing mixtures of the nanoparticles and monomer solutions. The swelling response of these composite systems to different crosslinking molecular weights, temperature, and the effect of the presence of the magnetic nanoparticles were examined. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2007
Femtosecond two‐photon high‐resolution 3D imaging, spatial‐volume rendering and microspectral characterization of immunolocalized MHC‐II and mLangerin/CD207 antigens in the mouse epidermis
Authors: Tirlapur Uday K. , Mulholland William J. , Bellhouse Brian J. , Kendall Mark , Cornhill J. Fredrick , Cui Zhanfeng
Published: August 2006

Langerhans cells (LCs) play a sentinel role by initiating both adaptive and innate immune responses to antigens pertinent to the skin. With the discovery of various LCs markers including antibodies to major histocompatibility complex class II (MHC‐II) molecules and CD1a, intracellular presence of racket‐shaped “Birbeck granules,” and very recently Langerin/CD207, LCs can be readily distinguished from other subsets of dendritic cells. Femtosecond two‐photon laser scanning microscopy (TPLSM) in recent years has emerged as an alternative to the single photon‐excitation based confocal laser scanning microscope (CLSM), particularly for minimally‐invasive deep‐tissue 3D and 4D vital as well as nonvital biomedical imaging. We have recently combined high resolution two‐photon immunofluorescence (using anti MHC‐II and Langerin/CD207 antibodies) imaging with microspectroscopy and advanced image‐processing/volume‐rendering modalities. In this work, we demonstrate the use of this novel state‐of‐the‐art combinational approach to characterize the steady state 3D organization and spectral features of the mouse epidermis, particularly to identify the spatial distribution of LCs. Our findings provide unequivocal direct evidence that, in the mouse epidermis, the MHC‐II and mLangerin/CD207 antigens do indeed manifest a high degree of colocalization around the nucleus of the LCs, while in the distal dendritic processes, mLangerin/CD207 antigens are rather sparsely distributed as punctuate structures. This unique possibility to simultaneously visualize high resolution 3D‐resolved spatial distributions of two different immuno‐reactive antigens, namely MHC‐II and mLangerin/CD207, along with the nuclei of LCs and the adjacent epidermal cells can find interesting applications. These could involve aspects associated with pragmatic analysis of the kinetics of LCs migration as a function of immuno‐dermatological responses during (1) human Immunodeficiency virus disease progression, (2) vaccination and targeted gene therapy, (3) skin transplantation/plastic surgery, (4) ultraviolet and other radiation exposure, (5) tissue‐engineering of 3D skin constructs, as well as in (6) cosmetic industry, to unravel the influence of cosmeceuticals. Microsc. Res. Tech., 2006. © 2006 Wiley‐Liss, Inc.
Intensity‐based signal separation algorithm for accurate quantification of clustered centrosomes in tissue sections
Authors: Fleisch Markus C. , Maxwell Christopher A. , Kuper Claudia K. , Brown Erika T. , Barcellos‐Hoff Mary Helen , Costes Sylvain V.
Published: August 2006

Centrosomes are small organelles that organize the mitotic spindle during cell division and are also involved in cell shape and polarity. Within epithelial tumors, such as breast cancer, and some hematological tumors, centrosome abnormalities (CAs) are common, occur early in disease etiology, and correlate with chromosomal instability and disease stage. In situ quantification of CA by optical microscopy is hampered by overlap and clustering of these organelles, which appear as focal structures. CA has been frequently associated with Tp53 status in premalignant lesions and tumors. Here the authors described an approach to accurately quantify centrosome frequencies in tissue sections and tumors, independently of background or noise levels. Applying simple optical rules in nondeconvolved conventional 3D images of stained tissue sections, the authors showed that they could evaluate more accurately and rapidly centrosome frequencies than with traditional investigator‐based visual analysis or threshold‐based techniques. The resulting population‐based frequency of centrosomes per nucleus could then be used to approximate the proportion of cells with CA in that same population. This was done by taking into account baseline centrosome amplification and proliferation rates measured in the tissue. Using this technique, the authors showed that 20–30% of cells have amplified centrosomes in Tp53 null mammary tumors. Microsc. Res. Tech., 2006. © 2006 Wiley‐Liss, Inc.
Head and neck cancer cells are efficiently infected by Ad5/35 hybrid virus
Authors: Suominen Elina , Toivonen Raine , Grenman Reidar , Savontaus Mikko
Published: August 2006

Background

Clinical gene therapy trials using standard Ad5‐based vectors have thus far demonstrated limited efficacy, most likely due to low expression levels of adenoviral receptors on tumor cells. We sought to analyze adenoviral receptor expression levels on primary head and neck squamous cell carcinoma (HNSCC) cells and to determine whether adenoviral retargeting to the CD46 receptor via the Ad5/35 system would increase therapeutic potential for HNSCC.

Methods

We used flow cytometric analyses to determine adenoviral receptor expression levels on nine primary HNSCC cells collected from cancer patients. Adenoviruses Ad5.LacZ and Ad5/35.LacZ were used to analyze the differences in viral transduction both in vitro and in a HNSCC tumor mouse model.

Results

Flow cytometric analyses demonstrated uniformly high CD46 expression in all cells studied (85–99%). In contrast, coxsackievirus and adenovirus receptor (CAR) expression was substantially lower and highly variable (1.6–62%). αv integrin expression was between 39–98%. In situ stainings for β‐galactosidase gene expression demonstrated that Ad5/35.LacZ was clearly more effective than Ad5.LacZ in transducing primary HNSCC cells. Quantification of β‐galactosidase expression revealed up to 65 times higher transgene expression from Ad5/35.LacZ than Ad5.LacZ. In vivo, β‐galactosidase expression was detected in a substantial area after a single intratumoral injection of Ad5/35.LacZ, whereas injection with Ad5.LacZ resulted in gene expression only in a few cells.

Conclusions

Our results demonstrate that the low and variable CAR expression levels limit the therapeutic efficacy of Ad5‐based strategies for HNSCC. In contrast, the effective in vivo transduction capacity of Ad5/35 warrants further development of this vector for the treatment of head and neck cancer. Copyright © 2006 John Wiley & Sons, Ltd.
Significance of the perfusion‐diffusion mismatch in chronic cerebral ischemia
Authors: Surikova Irina , Meisel Stefanie , Siebler Mario , Wittsack Hans‐Jörg , Seitz Rüdiger J.
Published: August 2006

Purpose

To determine whether the perfusion deficit could predict brain infarction in patients with chronic cerebral ischemia who experienced recurring episodes of neurological symptoms and showed a perfusion‐diffusion mismatch on magnetic resonance (MR) images.

Materials and Methods

In 53 consecutive patients (38 males and 15 females, 62 ± 13 years old) with ischemia in the middle cerebral artery (MCA) territory, lesion volumetry was performed on parametric maps of the time‐to‐peak, the cerebral blood volume, and diffusion‐weighted (DW) images. The infarct lesions were assessed on follow‐up T2‐weighted (T2W) MR images after eight days. Cerebrovascular changes were determined by time‐of‐flight (TOF) MR angiography (MRA). Inferential and correlation statistics were used.

Results

Patients with chronic ischemic brain disease (N = 39) who presented with a severe perfusion‐diffusion mismatch in the presence of a normal cerebral blood volume had no or small brain infarctions as found on follow‐up T2W images. MRA revealed widespread abnormalities of the basal cerebral arteries compatible with brain perfusion abnormalities. In contrast, in acute stroke patients (N = 14) the deficit of cerebral perfusion predicted the infarct lesion in the T2W images.

Conclusion

Our results suggest that in chronic cerebral ischemia the normal blood volume was maintained despite the depression of cerebral perfusion and recurring minor insults. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.
MR spectroscopy: Predicting long‐term neuropsychological outcome following pediatric TBI
Authors: Babikian Talin , Freier M. Catherin , Ashwal Stephen , Riggs Matt L. , Burley Todd , Holshouser Barbara A.
Published: August 2006

Purpose

To identify useful acute indicators of long‐term neurocognitive outcome beyond clinical variables for children and adolescents treated for a traumatic brain injury (TBI).

Materials and Methods

The efficacy of magnetic resonance spectroscopy (MRS) acquired 6 ± 4 days after TBI in 20 children/adolescents in predicting intellectual and neuropsychological functioning one to four years post injury was assessed. Short echo‐time single voxel MRS (SVS) from normal‐appearing brain was compared to intermediate echo‐time multivoxel MR spectroscopic imaging (MRSI) from normal‐appearing and visibly‐injured brain acquired through the level of the corpus callosum (CC).

Results

N‐acetyl aspartate (NAA) was moderate to strongly correlated with cognitive scores. Mean NAA/creatine (Cre) from MRSI alone explained over 40% of the variance in cognitive scores and 18% of the variance above and beyond demographic and clinical variables alone. Mild to moderate associations were noted between SVS metabolites (glutamate/glutamine [Glx] and myoinositol [mI]) and cognitive scores, with no such associations apparent for choline (Cho) or Cre. Exploratory analyses revealed trends for regional neuroimaging data and specific cognitive abilities.

Conclusion

Acute MR spectroscopy of the pediatric brain injury patient improves prognostic ability and may provide valuable information for early treatment and intervention planning. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.
Desipramine prevents the sustained increase in corticotropin‐releasing hormone‐like immunoreactivity induced by repeated immobilization stress in the rat central extended amygdala
Authors: Santibañez Marcos , Gysling Katia , Forray María Inés
Published: August 2006

Clinical and experimental studies have shown that the activation of corticotropin‐releasing hormone (CRH) and noradrenergic systems mediate stress‐induced anxiety. Repeated immobilization stress (RIS) has been shown to induce long‐lasting anxiety behavior and changes in noradrenaline turnover. The present work was aimed at studying the effect of RIS on the in situ expression of CRH‐LI in the central extended amygdala and paraventricular nucleus of the hypothalamus (PVN). Our results showed that RIS for 15 days induces a significant increase of CRH‐LI expression in the central extended amygdala. The increase in CRH‐LI expression in the central extended amygdala was sustained even after a 25‐day stress‐free period. The concomitant administration of desipramine (DMI), a specific noradrenaline uptake inhibitor, fully prevented the RIS‐induced increase in CRH expression. RIS also induced an increase of CRH‐LI expression in the PVN that was prevented by the concomitant DMI administration. In contrast to the sustained effect observed in the central extended amygdala, the RIS‐induced increase of CRH‐LI expression in the PVN was nonlasting. DMI administration also prevented the RIS‐induced increase of adrenal gland weight. The present findings showing that RIS induces a sustained increase of CRH expression in the central extended amygdala suggest that the repeated activation of CRH neurons and CRH receptors in the central extended amygdala may underlie the long‐lasting anxiety behavior induced by RIS. Further studies should address the mechanisms involved in the effect of DMI and its eventual relevance in the therapeutic actions of DMI. © 2006 Wiley‐Liss, Inc.
Neuroprotective role of ERK1/2 and ERK5 in a dopaminergic cell line under basal conditions and in response to oxidative stress
Authors: Cavanaugh Jane E. , Jaumotte Juliann D. , Lakoski Joan M. , Zigmond Michael J.
Published: August 2006

Loss of motor function in Parkinson's disease is due in part to degeneration of dopamine (DA) neurons. Pharmacological evidence suggests that the mitogen‐activated protein kinase signaling pathways involving extracellular signal‐regulated kinases (ERKs) play important roles in neuroprotection of DA neurons. However, the relative roles of the several ERK isoforms in the viability of DA neurons have not yet been determined. In the present study, we investigated the contributions of ERK5, as well as ERK1/2, to MN9D cell survival under basal conditions and in response to 6‐hydroxydopamine (6‐OHDA). We observed that U0126, an inhibitor of ERK activation, decreased basal survival of these cells. To differentiate between ERK1/2 and ERK5, cells were transfected with a dominant negative form of either ERK5 or MEK1, the upstream activator of ERK1/2. Transfection of MN9D cells with either dominant negative construct mimicked U0126, reducing cell survival. Moreover, transfection of the cells in such a way as to increase ERK5 or ERK1/2 activity inhibited 6‐OHDA‐induced cell death, although this effect was significant only in the case of ERK1/2 activation. These studies suggest that activations of ERK5 and ERK1/2 both promote basal DA cell survival and that ERK1/2 also protects DA cells from oxidative stress. These are the first studies to demonstrate a role for ERK5 in DA neuronal survival and to investigate the relative roles of ERK1/2 and ERK5 in basal DA survival and neuroprotection from oxidative stress. © 2006 Wiley‐Liss, Inc.
Knockdown of amyloid precursor protein normalizes cholinergic function in a cell line derived from the cerebral cortex of a trisomy 16 mouse: An animal model of down syndrome
Authors: Opazo Patricia , Saud Katherine , de Saint Pierre Michelle , Cárdenas Ana María , Allen David D. , Segura‐Aguilar Juan , Caviedes Raúl , Caviedes Pablo
Published: August 2006

We have generated immortal neuronal cell lines from normal and trisomy 16 (Ts16) mice, a model for Down syndrome (DS). Ts16 lines overexpress DS‐related genes (App, amyloid precursor protein; Sod1, Cu/Zn superoxide dismutase) and show altered cholinergic function (reduced choline uptake, ChAT expression and fractional choline release after stimulation). As previous evidence has related amyloid to cholinergic dysfunction, we reduced APP expression using specific mRNA antisense sequences in our neuronal cell line named CTb, derived from Ts16 cerebral cortex, compared to a cell line derived from a normal animal, named CNh. After transfection, Western blot studies showed APP expression knockdown in CTb cells of 36% (24 hr), 40.4% (48 hr), and 50.2% (72 hr) compared to CNh. Under these reduced APP levels, we studied 3H‐choline uptake in CTb and CNh cells. CTb, as reported previously, expressed reduced choline uptake compared to CNh cells (75%, 90%, and 69% reduction at 1, 2, and 5 min incubation, respectively). At 72 hr of APP knockdown, choline uptake levels were essentially similar in both cell types. Further, fractional release of 3H‐choline in response to glutamate, nicotine, and depolarization with KCl showed a progressive increase after APP knockdown, reaching values similar to those of CNh after 72 hr of transfection. The results suggest that APP overexpression in CTb cells contributes to impaired cholinergic function, and that gene knockdown in CTb cells is a relevant tool to study DS‐related dysfunction. © 2006 Wiley‐Liss, Inc.
Bcl2 enhances survival of newborn neurons in the normal and ischemic hippocampus
Authors: Sasaki Tsutomu , Kitagawa Kazuo , Yagita Yoshiki , Sugiura Shiro , Omura‐Matsuoka Emi , Tanaka Shigeru , Matsushita Kohji , Okano Hideyuki , Tsujimoto Yoshihide , Hori Masatsugu
Published: August 2006

Neuronal progenitors in the adult hippocampus continually proliferate and differentiate to the neuronal lineage, and ischemic insult promotes hippocampal neurogenesis. However, newborn neurons show a progressive reduction in numbers during the initial few weeks, therefore, enhanced survival of newborn neurons seems to be essential for therapeutic strategy. Bcl‐2 is a crucial regulator of programmed cell death in CNS development and in apoptotic and necrotic cell death. Therefore, we tested whether Bcl‐2 overexpression enhances survival of newborn neurons in the adult mouse hippocampus under normal and ischemic conditions. Many newborn neurons in the hippocampal dentate gyrus undergo apoptosis. Human Bcl‐2 expression in NSE‐bcl‐2 transgenic mice began at the immature neuronal stage and remained constant in surviving mature neurons. Bcl‐2 significantly increased survival of newborn neurons under both conditions, but particularly after ischemia, with decreased cell death of newborn neurons in NSE‐bcl‐2 transgenic mice. We also clarified the effect by Bcl‐2 overexpression of enhanced survival of newborn neurons in primary hippocampal cultures with BrdU labeling. These findings suggest that Bcl‐2 plays a crucial role in adult hippocampal neurogenesis under normal and ischemic conditions. © 2006 Wiley‐Liss, Inc.
Age‐dependent modulation of hippocampal long‐term potentiation by antioxidant enzymes
Authors: Watson J.B. , Arnold M.M. , Ho Y.‐S. , O'Dell T.J.
Published: August 2006

Oxidative stress has long been associated with normal aging and age‐related neurodegenerative disorders such as Alzheimer's disease (AD) and Parkinson's disease (PD). However, it is now evident that reactive oxygen species (ROS) such as superoxide (O) and hydrogen peroxide (H2O2) also play pivotal roles in normal cell signaling. The focus of the present study was to examine the effects of the antioxidant enzymes CuZnSOD (SOD1) and catalase, which produce and remove H2O2, respectively, on long‐term potentiation (LTP) forms of synaptic plasticity during aging. Consistent wth previous studies, LTP, when induced in vitro in CA1 of the hippocampus with a high‐frequency stimulation protocol, is significantly reduced in slices from older mice (22–26 months) relative to younger mice (2–4 months). Neither knockout of the endogenous catalase gene (Cat KO) nor acute enzymatic treatment with SOD1 altered LTP in slices from adult mice. Conversely, enzymatic applications of SOD1 inhibited LTP in slices from older mice. A much different set of results emerges with exogenous applications of catalase to hippocampal slices. Catalase significantly inhibited LTP in slices from adult mice but reversed age‐related LTP deficits in slices from older mice. Measurements of H2O2 showed that exogenous treatments with catalase lowered H2O2 in synapse‐enriched synaptoneurosome (SN) fractions prepared from adult mice. Notably, SNs from both Cat KO and old mice were deficient in removing extracellular challenges of H2O2. Overall, the results suggest that dynamic alterations in extracellular H2O2 metabolism affect synaptic plasticity in the hippocampus during aging. © 2006 Wiley‐Liss, Inc.
Study of the influence of some organics as thiourea derivatives and butindiol in steel pickling baths
Authors: Fernández Díaz L. M. , Bendick O. , Ostwald C. , Appel T.
Published: August 2006

The corrosion inhibition effect of the following organic additives: 2‐butin‐1,4‐diol (BD), N,N′‐dimethylthiourea (DMTU), N,N′‐diethylthiourea (DETU) and N,N′‐diisopropylthiourea (DITU), in steel pickling baths (sulphuric acid solutions) was studied by means of weight loss and electrochemical measurements like open circuit potential (OCP), polarization curves and impedance spectroscopy (EIS). A significant decrease in the corrosion rate was observed in presence of the investigated compounds depending on the nature and the concentration of the additives. The weight loss experiments show an inhibitory efficiency that reaches values beyond 98 %. The protective effect increases with the enlargement of the lateral chain size in the case of the thioureas. The electrochemical experiments show also a protective effect of the organic additives against corrosion. Their adsorptive behaviour is found to follow the Langmuir model.
Poly(amine‐amide‐imide)s Bearing Pendent N‐Carbazolylphenyl Moieties: Synthesis and Electrochromic Properties
Authors: Liou Guey‐Sheng , Chen Hwei‐Wen , Yen Hung‐Ju
Published: August 2006

Summary: A series of novel poly(amine‐amide‐imide)s with pendent N‐carbazolylphenyl units that have inherent viscosities of 0.45–0.66 dL · g−1 are prepared from various aromatic bis(trimellitimide)s and the new carbazole‐based aromatic diamine, 4,4′‐diamino‐4″‐N‐carbazolyltriphenylamine, by direct polycondensation. All the polymers are readily soluble in polar organic solvents. Flexible, amorphous, and deep reddish films of poly(amine‐amide‐imide)s can be obtained by solution casting, and have useful levels of thermal stability associated with high glass transition temperatures (307–343 °C), 10% weight‐loss temperatures in excess of 500 °C, and char yields at 800 °C in nitrogen higher than 65%. These polymers exhibit a maximum UV‐vis absorption at 300 nm with a fluorescence emission maxima around 449–454 nm in N‐methyl‐2‐pyrrolidinone solution. The hole‐transporting and electrochromic properties are examined by electrochemical and spectroelectrochemical methods. Cyclic voltammograms of the poly(amine‐amide‐imide) films cast onto an indium tin oxide‐coated glass substrate exhibit a reversible oxidation at 0.84 V and irreversible oxidation redox couples at 1.27 V versus Ag/AgCl in acetonitrile solution, and reveal good stability of electrochromic characteristics, with a color change from yellowish to green at applied potentials ranging from 0.00 to 0.95 V.

Structure and properties of PAI‐2M (bottom left: cyclic voltammetry; bottom right: potential‐step absorptometry).

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Structure and properties of PAI‐2M (bottom left: cyclic voltammetry; bottom right: potential‐step absorptometry).
Multicyclic Polyethers Derived from Tetra(bromomethyl)methane and Flexible Diphenols
Authors: Kricheldorf Hans R. , Schellenberg Johann , Schwarz Gert
Published: August 2006

Summary: Soluble multicyclic polyethers have been prepared by the polycondensation of tetra(bromomethyl)methane with various diphenols. The influence of the diphenol on the competition between cyclization and chain growth (yielding insoluble gels) is studied for feed ratios of 2/1 (a2/b4 monomer) and high conversions. With 4‐tert‐butylcatechol or 2,2′‐dihydroxy‐1,1′‐binaphthyl, mainly monomeric spiro‐cycles are formed. Soluble multicycles free of end‐groups are only obtained from α,ω‐bis(3‐hydroxyphenoxy) alkanes. The structure of the reaction products has been characterized by 1H NMR spectroscopy and MALDI‐TOF mass spectrometry. As characteristic properties of the compact multicyclic structure, low solution viscosities in combination with high polydispersities are found. DSC measurements prove an amorphous character with glass‐transition temperatures in the range of 45–85 °C.

Formation of soluble multicyclic oligoethers.

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Formation of soluble multicyclic oligoethers.
Cover Picture: Macromol. Chem. Phys. 17/2006
Authors: Takeuchi Daisuke , Okada Takeshi , Kuwabara Junpei , Osakada Kohtaro
Published: August 2006

Cover: Palladium complexes initiate the living copolymerization of CO with methylenecyclopropane with a dihydroanthrene group, and produce polymers containing cis‐fused six‐membered ring. Bases such as DBU induce epimerization of the monomer unit to afford the polymer with trans‐fused rings selectively. Further details can be found in the Full Paper by D. Takeuchi, T. Okada, J. Kuwabara, and K. Osakada* on page 1546.
Kinetics and Mechanistic Investigation of Hydrotalcite‐Catalyzed Melt Synthesis of Poly(ethylene terephthalate)
Authors: El‐Toufaili Faissal‐Ali , Feix Gunter , Reichert Karl‐Heinz
Published: August 2006

Summary: Hydrotalcite‐catalyzed polycondensation of BHET was studied by thermogravimetry to elucidate the kinetics. The reaction was found to follow second‐order kinetics with respect to hydroxyl end groups. The overall activation energy of the polycondensation was found to decrease with increasing catalyst concentration before it leveled out to the value of 93 kJ · mol−1 at high catalyst concentration. This is a result of the uncatalyzed reaction that takes place parallel to the catalyzed one. The activation energy of the uncatalyzed path was found to be 156 kJ · mol−1. IR spectroscopy and XRD showed that the monomer intercalates between the layers of hydrotalcite at the beginning of the reaction enabling the complexation of oxygen‐containing functional groups with the hydroxide groups of the catalyst. Based on these findings a polycondensation mechanism is proposed. One end group of the monomer is activated in the form of alkoxide that counterbalances the positive charge of the hydrotalcite layer. This alkoxide group attacks an ester carbonyl group fixed close to it, generating a new ester bond and a glycoxide species. The role of hydrotalcite is to activate the reactants, rendering the attacking hydroxyl group more nucleophilic and the ester carbonyl group more electrophilic, and at the same time fixing the reactant together in a favorable geometry.

Intercalation of BHET in the gallery of HT layers in a twisted alkoxide form.

magnified image

Intercalation of BHET in the gallery of HT layers in a twisted alkoxide form.
A three‐dimensional transmission line with coplanar waveguide features
Authors: Farcich Nick J. , Asbeck P.M.
Published: August 2006

A new type of coplanar‐like transmission line is presented based on using the available third dimension to extend the surface area of the center conductor and ground planes. A prototype 3D coplanar line was fabricated using polydimethylsiloxane as the substrate material. Experimental and full‐wave electromagnetic simulation results confirm the structure's viability as a low loss, reduced phase velocity microwave waveguide that also has good dispersion characteristics. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2189–2192, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21881
An SRR based microwave absorber
Authors: Bilotti Filiberto , Nucci Luca , Vegni Lucio
Published: August 2006

In this letter, the authors present the design of a resonant microwave absorber made by a proper array of split ring resonators (SRRs). The physical mechanism behind the operation of the proposed component is based on the SRR resonance, arising when the structure is excited by a properly polarized impinging wave. A resistive sheet, located nearby the resonating SRRs, absorbs the electromagnetic energy of the incoming field, without destroying the resonance condition of the SRRs. The two relevant features of the proposed absorber are its electrical thickness, which is very small compared with the operating wavelength, and the lack of a metallic backing, which represent a common part of conventional absorber layouts. The full‐wave simulations presented in the paper confirm the effectiveness of the proposed absorber for microwave applications. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2171–2175, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21891
Fibre Bragg grating interrogation based on high‐birefringence fibre loop mirror for strain temperature discrimination
Authors: Frazão O. , Marques L. M. , Baptista J. M.
Published: August 2006

In this work, we present a fiber Bragg grating interrogation based on high‐birefringence fiber loop mirror for strain–temperature discrimination. Due to spectral response of the optical filters it is possible to determine the variation of the wavelength and the optical power of the Bragg grating sensor when subject to strain or temperature. Maximum errors of ±0.4°C and ±12 με are reported over 80°C and 2000 με measurement ranges. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2326–2328, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21894
Performance analysis of bidirectional hybrid WDM/SCM‐PON link based on reflective semiconductor optical amplifier
Authors: Kim Tae‐Young , Kang Jeung‐Mo , Han Sang‐Kook
Published: August 2006

The effect of noise on the transmission performance of an RSOA‐utilized bidirectional hybrid WDM/SCM‐PON link is experimentally analyzed. The link used in experiment allows 33‐km bidirectional transmission with 622‐Mbps NRZ signal for downstream and 20‐Mbps SCM signal at 1.5‐GHz RF carrier for upstream. In the link, the RSOA is used as a remodulator in optical network unit (ONU), which plays an important role in the overall noise characteristic of the link. Experimental results show that by properly controlling the gain of the RSOA, the effect of backreflection and backscattering noise can be reduced. Experimental results also suggest that both the uplink and the downlink signals should be modulated to reduce the effect of noise. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2301–2309, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21896
Electromagnetic energy in absorptive and dispersive medium based on the assembly of atomic oscillators
Authors: Cao Haibo , Cui Tie Jun
Published: August 2006

On the basis of the idealized structure of an atomic medium described by an assembly of independent oscillators, expressions for the stored electric and magnetic energy densities in absorptive and dispersive medium are derived. Such formulas are also valid for a left‐handed medium (LHM), where the permittivity and permeability are simultaneously less than zero within a frequency band. These formulas are completely equivalent to those derived from a general definition of electromagnetic energy density using the classical electromagnetics. It has been shown that the stored energy densities, no matter in a right‐handed medium or in a left‐handed medium, are always positive. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2288–2291, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21899
Study of a CPW‐fed circular slot antenna for UWB communications
Authors: Consoli Fabrizio , Maimone Fabio , Barbarino Sebastiano
Published: August 2006

A numerical and experimental study of a circular‐slot antenna, fed by a coplanar waveguide with a rectangular stub, is proposed in this paper for ultra‐wideband communications. The antenna impedance bandwidth, phase linearity, gain and radiation patterns are presented, together with the time‐domain impulse response. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2272–2277, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21900
Performance comparison between uniformly and nonuniformly spaced adaptive antennas with respect to tolerance to pointing errors
Authors: Al‐Ka'bi Amin , Bialkowski Marek E. , Homer John
Published: August 2006

The paper presents theoretical and experimental investigations into performances of narrowband uniformly and nonuniformly spaced adaptive linear dipole array antennas that are subjected to pointing errors. The analysis focuses on the array's output Signal to Interference plus Noise Ratio. The presence of mutual coupling between the array elements is taken into account. It is shown that the array's tolerance to pointing errors can be enhanced by controlling the interelement spacing. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2233–2237, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21904
Compact ultra‐wideband planar tapered slot antenna for use in a microwave imaging system
Authors: Abbosh A. M. , Kan H. K. , Bialkowski M. E.
Published: August 2006

The design of an ultra‐wideband planar tapered slot antenna for use in a circular cylindrical microwave imaging system is presented. The antenna was designed assuming high dielectric substrate material Rogers RT6010LM to achieve its compact size. The developed antenna element (50 × 50 mm2) features a 10‐dB return loss bandwidth from 2.75 GHz to more than 11 GHz. The gain of the antenna is between 3.5 and 9.4 dBi over the 3–10 GHz band. The experimental tests showed that the manufactured antenna element supports transmission of narrow pulses with negligible distortions, as required in the microwave imaging system. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2212–2216, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21906
Reactive loaded microstrip leaky wave antenna for low cost beam steering applications
Authors: Augustin Gijo , Shynu S. V. , Mohanan P. , Aanandan C. K. , Vasudevan K.
Published: August 2006

A novel fixed frequency beam scanning microstrip leaky wave antenna is reported. The beam scanning at fixed frequency is achieved by reactive loading. Simulation and measured results shows frequency scanability of 80° as well as fixed frequency beam steering of 68° over the −10 dB impedance band of 4.56–5.06 GHz © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2299–2301, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21912
Compact LTCC bandpass filter design with controllable transmission zeros in the stopband
Authors: Deng Jianhua , Wang Bing‐Zhong , Gan Tiguo
Published: August 2006

Method of designing a modified Chebyshev bandpass filter with controllable transmission zeros in the stopband is described. A novel compact structure of this kind of filter with a transmission zero located at higher stopband for low temperature co‐fired ceramic implementation is proposed. The filter has promising potential applications in miniaturized wireless communication systems. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2261–2264, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21916
Growth and studies of optical properties of double‐doped In:Fe:LiTaO3 crystal
Authors: Ma Decai , Wang Biao , Fang Shuangquan , Zhang Tao , Wang Rui , Wei Yuan
Published: August 2006

In:Fe:LiTaO3 crystals were grown in an air atmosphere using the Czochralski method. The photorefractive properties were measured by the two‐wave coupling experiments, and light‐induced scattering was used to characterize the optical damage. It was found that the photorefractive response speed of In:Fe:LiTaO3 was about four times faster than that of Fe:LiTaO3, and the resistance ability to optical damage was drastically improved. The increase in damage resistance and faster response speed could be attributed to the Fe3+ losing their electron acceptor properties and, therefore, an increase in photoconductivity. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2227–2230, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21919
Wide band dumbbell‐shaped patch antenna
Authors: Jacob K. Francis , Suma M. N. , Joseph Manoj , Mohanan P.
Published: August 2006

The design and radiation characteristics of a wide band dumbbell‐shaped patch excited by planar strip monopole with truncated ground plane is proposed in this letter. The antenna can be easily modified for dual band operation by adjusting the location of the patch over the planar monopole. The antenna offers a bandwidth of 35 and 9% at 3.2 and 5.3 GHz bands, respectively. The overall area of the antenna including the 50 Ω line feed is only 65 × 65 mm2. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2295–2296, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21926