bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of microglia in the chick embryo spinal cord: Implications in the regulation of motoneuronal survival and death
Authors: Calderó Jordi , Brunet Núria , Ciutat Dolors , Hereu Marta , Esquerda Josep E.
Published: April 2009

The role of microglia during normal development of the nervous system is still not well understood. In the present study, a chick embryo model was used to examine the development of microglia in the spinal cord and characterize their changes in response to naturally occurring and pathological death of motoneurons (MNs). The microglial response to MN axotomy and the effects of microglial activation on MN survival were also studied. We found that: 1) macrophages/microglial cells were present in the spinal cord at early developmental stages (E3) and that they were recruited after normal and induced MN apoptosis; 2) although many microglial cells were seen phagocytosing apoptotic bodies, a proportion of dying cells were devoid of engulfing microglia; 3) axotomy of mature MNs was accompanied by microglial activation in the absence of MN death; 4) excitotoxic (necrotic) MN death provoked a rapid and massive microglial recruitment with phagocytic activity; 5) lipopolysaccharide‐induced microglial activation in vivo resulted in the death of immature, but not mature, microglia; and 6) overactivation of microglia modulated the survival of mature MNs, either by killing them or by enhancing their vulnerability to die in response to a mild injury. Taken together, these observations indicate that normal microglia do not play an active role in triggering apoptosis of developing MNs. Rather, they act as phagocytes for the removal of dying cells during the process of programmed cell death. © 2009 Wiley‐Liss, Inc.
In vitro analysis of glial cell function in ganglioside‐deficient mice
Authors: Silajdžić Edina , Willison Hugh J. , Furukawa Koichi , Barnett Susan C.
Published: April 2009

Gangliosides are a family of sialic acid–containing glycosphingolipids highly enriched in neuronal and glial membranes, where they play pleiotropic roles in nervous system function. In this glial cell biological study, we used mice deficient in glycosyltransferases involved in ganglioside biosynthesis to gain insights into the possible role of ganglioside overexpression or deficiency on glial cell proliferation, migration, and differentiation in vitro. Primary cultures of olfactory ensheathing cells, oligodendrocyte lineage cells, and Schwann cells isolated from β1,4‐N‐acetylgalactosaminyl (β1,4‐GalNAc) transferase– and α‐2,8‐sialyltransferase‐deficient mice demonstrated subtle differences in their behavior when compared with wild‐type glia. Oligodendrocyte–axonal interactions were investigated in dissociated embryonic mixed spinal cord cultures in which axonal ensheathment with myelin internodes and organized nodes of Ranvier form. In these myelinating cultures, deficiency of complex gangliosides, as found in β1,4‐GalNAc T−/− mice, resulted in the temporal disorganization of Kv and Na+ channels at the nodes of Ranvier, similar to that seen in β1,4‐GalNAc T−/− mice in vivo. These data show that glycosyltransferase deficiency and the consequent ganglioside imbalance has subtle effects on a range of glial cell functions and that in vitro systems can be used to explore these in ways that complement whole animal physiology. Our results are also consistent with the absence of gross neurodevelopmental dysfunction in mice lacking a variety of different gangliosides, suggesting that ganglioside redundancy and substitution are mechanisms that compensate for the lack of a full complement of complex gangliosides. © 2009 Wiley‐Liss, Inc.
Functional and immunocytochemical characterization of D‐serine transporters in cortical neuron and astrocyte cultures
Authors: Shao Zongjun , Kamboj Amit , Anderson Christopher M.
Published: April 2009

D‐serine is an endogenous coagonist of N‐methyl‐D‐aspartate (NMDA) receptors that plays an important role in synaptic function, neuronal development, and excitotoxicity. Mechanisms of D‐serine transport are important in regulation of extracellular D‐serine concentration and therefore of these critical processes. D‐serine can be transported with low affinity through the Na+‐dependent amino acid transporter termedASCT2, whereas high‐affinity D‐serine uptake has been reported through the Na+‐independent transporter termedasc‐1. We investigated immunoreactivity for ASCT2 and asc‐1 and D‐serine transport kinetics in cultured cortical neurons and astrocytes to gain insight into how D‐serine transporters regulate CNS D‐serine levels. Both neurons and astrocytes exhibited low‐affinity Na+‐dependent D‐serine uptake (KT> 1 mM) with broad substrate selectivity that was consistent with uptake through ASCT2. Both neurons and astrocytes also stained positively for ASCT2 in immunocytochemistry studies. Neurons but not astrocytes stained positively for the high‐affinity D‐serine transporter asc‐1, but no evidence of functional asc‐1 could be detected in neurons with conditions that produced such activity in cortical synaptosomes. These data support ASCT2 function in both neuron and astrocyte cultures and identify a discrepancy between observed asc‐1 immunoreactivity and lack of functional asc‐1 activity in neuron cultures. Together these findings further our knowledge of the processes that govern D‐serine regulation. © 2009 Wiley‐Liss, Inc.
Possible promotion of neuronal differentiation in fetal rat brain neural progenitor cells after sustained exposure to static magnetism
Authors: Nakamichi Noritaka , Ishioka Yukichi , Hirai Takao , Ozawa Shusuke , Tachibana Masaki , Nakamura Nobuhiro , Takarada Takeshi , Yoneda Yukio
Published: April 2009

We have previously shown significant potentiation of Ca2+ influx mediated by N‐methyl‐D‐aspartate receptors, along with decreased microtubules‐associated protein‐2 (MAP2) expression, in hippocampal neurons cultured under static magnetism without cell death. In this study, we investigated the effects of static magnetism on the functionality of neural progenitor cells endowed to proliferate for self‐replication and differentiate into neuronal, astroglial, and oligodendroglial lineages. Neural progenitor cells were isolated from embryonic rat neocortex and hippocampus, followed by culture under static magnetism at 100 mT and subsequent determination of the number of cells immunoreactive for a marker protein of particular progeny lineages. Static magnetism not only significantly decreased proliferation of neural progenitor cells without affecting cell viability, but also promoted differentiation into cells immunoreactive for MAP2 with a concomitant decrease in that for an astroglial marker, irrespective of the presence of differentiation inducers. In neural progenitors cultured under static magnetism, a significant increase was seen in mRNA expression of several activator‐type proneural genes, such as Mash1, Math1, and Math3, together with decreased mRNA expression of the repressor type Hes5. These results suggest that sustained static magnetism could suppress proliferation for self‐renewal and facilitate differentiation into neurons through promoted expression of activator‐type proneural genes by progenitor cells in fetal rat brain. © 2009 Wiley‐Liss, Inc.
Desacyl‐ghrelin and synthetic GH‐secretagogues modulate the production of inflammatory cytokines in mouse microglia cells stimulated by β‐amyloid fibrils
Authors: Bulgarelli Ilaria , Tamiazzo Laura , Bresciani Elena , Rapetti Daniela , Caporali Simona , Lattuada Donatella , Locatelli Vittorio , Torsello Antonio
Published: April 2009

Data from Alzheimer's disease (AD) patients and AD animal models demonstrate the accumulation of inflammatory microglia at sites of insoluble fibrillar β‐amyloid protein (fAβ) deposition. It is known that fAβ binds to CD36, a type B scavenger receptor also involved in internalization of oxidized low‐density lipoprotein (LDL), and initiate a signaling cascade that regulates microglial recruitment, activation, and secretion of inflammatory mediators leading to neuronal dysfunction and death. The recent demonstration of a binding site for the growth hormone secretagogues (GHS) on CD36 prompted us to ascertain whether ghrelin and synthetic GHS could modulate the synthesis of inflammatory cytokines in fAβ‐activated microglia cells. We demonstrate that N9 microglia cells express the CD36 and are a suitable model to study the activation of inflammatory cytokines synthesis. In fact, in N9 cells exposed to fAβ25–35 for 24 hr, the expression of interleukin (IL)‐1β and IL‐6 mRNA significantly increased. Interestingly, 10−7 M desacyl‐ghrelin, hexarelin, and EP80317 in the nanomolar range effectively counteracted fAβ25–35 stimulation of IL‐6 mRNA levels, whereas ghrelin was ineffective. Similarly, the effects of fAβ25–35 on IL‐1β mRNA levels were attenuated by desacyl‐ghrelin, hexarelin, and EP80317, but not ghrelin. Because we have observed that the specific GHS receptor GHS‐R1a is not expressed in N9 cells, the actions of GHS should be mediated by different receptors. Reportedly, hexarelin and EP80317 are capable of binding the CD36 in mouse macrophages and reducing atherosclerotic plaque deposition in mice. We conclude that desacyl‐ghrelin, hexarelin, and EP80317 might interfere with fAβ activation of CD36 in microglia cells. © 2009 Wiley‐Liss, Inc.
Sustained hydrogen peroxide stress decreases lactate production by cultured astrocytes
Authors: Liddell Jeff R. , Zwingmann Claudia , Schmidt Maike M. , Thiessen Anette , Leibfritz Dieter , Robinson Stephen R. , Dringen Ralf
Published: April 2009

Oxidative stress and disrupted energy metabolism are common to many pathological conditions of the brain. Because astrocytes play an important role in the glucose metabolism of the brain, we have investigated whether sustained oxidative stress affects astroglial glucose metabolism with cultured primary rat astrocytes as a model system. Cultured astrocytes were exposed to a sustained concentration of approximately 50 μM H2O2 in the presence of [U‐13C]glucose, and cellular and extracellular contents of lactate and glucose were analysed by enzymatic assays and NMR spectroscopy. Exposure of the cells to sustained H2O2 stress for up to 120 min significantly lowered the rate of lactate accumulation in the media to 61% ± 14% of that in cultures incubated without peroxide. In addition, the ratio of lactate release to glucose consumption was lowered in peroxide‐treated astrocytes to 77% ± 13% of that in control cells, and the specific activity of glyceraldehyde‐3‐phosphate dehydrogenase had declined to about 10% of control cells within 90 min. In addition, the 13C enrichment of intracellular and extracellular [13C]lactate was about 30% and 95%, respectively, and was not affected by the presence of peroxide, demonstrating that two metabolic pools of lactate are present in cultured astrocytes. The decreased rate of lactate production by astrocytes that have been exposed to peroxide stress is a new example of an alteration by oxidative stress of an important metabolic pathway in astrocytes. Such alterations could contribute to the pathological conditions that have been connected with oxidative stress and disrupted energy metabolism in the brain. © 2009 Wiley‐Liss, Inc.
Activated retinal glia promote neurite outgrowth of retinal ganglion cells via apolipoprotein E
Authors: Lorber Barbara , Berry Martin , Douglas Michael R. , Nakazawa Toru , Logan Ann
Published: April 2009

In the present study, we investigated the role and mechanism through which activated retinal glia stimulate retinal ganglion cell (RGC) neurite outgrowth. We have found that the level of retinal glial activation correlates directly with enhanced RGC neurite outgrowth after a preconditioning intravitreal Zymosan injection. Reduction in the number of activated glia in primary rat retinal cultures led to significantly reduced RGC neurite outgrowth. Glial‐related neurite outgrowth appears to be, at least in part, mediated via apolipoprotein E (ApoE), which is expressed by activated retinal astrocytes and Müller glia. ApoE‐deficient mice showed significantly reduced RGC neurite outgrowth potential after intravitreal Zymosan injection compared with age‐matched wild‐type animals. These observations suggest that ApoE, expressed by activated retinal glia, stimulates RGC neurite outgrowth after intravitreal Zymosan injection. © 2009 Wiley‐Liss, Inc.
Insulin‐like growth factor‐I‐stimulated Akt phosphorylation and oligodendrocyte progenitor cell survival require cholesterol‐enriched membranes
Authors: Romanelli Robert J. , Mahajan Kedar R. , Fulmer Clifton G. , Wood Teresa L.
Published: April 2009

Previously we showed that insulin‐like growth factor‐I (IGF‐I) promotes sustained phosphorylation of Akt in oligodendrocyte progenitor cells (OPCs) and that Akt phosphorylation is required for survival of these cells. The direct mechanisms, however, by which IGF‐I promotes Akt phosphorylation are currently undefined. Recently, cholesterol‐enriched membranes (CEMs) have been implicated in regulation of growth factor‐mediated activation of the PI3K/Akt pathway and survival of mature oligodendrocytes; however, less is know about their role in OPC survival. In the present study, we investigate the role of CEMs in IGF‐I‐mediated Akt phosphorylation and OPC survival. We report that acute disruption of membrane cholesterol with methyl‐β‐cyclodextrin results in altered OPC morphology and inhibition of IGF‐I‐mediated Akt phosphorylation. We also report that long‐term inhibition of cholesterol biosynthesis with 25‐hydroxycholesterol blocks IGF‐I stimulated Akt phosphorylation and cell survival. Moreover, we show that the PI3K regulatory subunit, p85, Akt, and the IGF‐IR are sequestered within cholesterol‐enriched fractions in steady‐state stimulation of the IGF‐IR and that phosphorylated Akt and IGF‐IR are present in cholesterol‐enriched fractions with IGF‐I stimulation. Together, the results of these studies support a role for CEMs or “lipid rafts” in IGF‐I‐mediated Akt phosphorylation and provide a better understanding of the mechanisms by which IGF‐I promotes OPC survival. © 2009 Wiley‐Liss, Inc.
Effects of the Tibetan Plateau on the Asian summer monsoon: a numerical case study using a regional climate model
Authors: Song Jee‐Hey , Kang Hyun‐Suk , Byun Young‐Hwa , Hong Song‐You
Published: April 2009

To understand impacts of the Tibetan Plateau (TP) upon the Asian summer monsoon (ASM), including both the Indian summer monsoons (ISM) and East Asian summer monsoons (EASM), a series of numerical experiments using the National Centers for Environmental Prediction (NCEP) regional spectral model (RSM) are conducted with various TP heights ranging from the flat surface (1.2 km) to 140% of the actual height. It was found that an increase in the TP height leads to an increase in the simulated ISM precipitation over northern India and conversely a decrease in the height leads to a decrease in precipitation. This sensitivity is associated with both the thermal and dynamical effects of the TP; however, although the ISM precipitation over India is affected by the changes in atmospheric circulation, it is not directly affected by the thermal effect. The thermal effect of surface heating plays a role in developing positive vorticity with a consequent increase in monsoon precipitation over northern India. The width of the plateau also seems to be associated with the intensity of the sensitivity for the ISM region. For the EASM region, the orographic effect caused by changes in the lower‐atmospheric circulation and its link with upper‐atmospheric circulation are crucial to the monsoon circulation and precipitation. With increased TP height, the monsoon precipitation moves inland in a northwestward direction, which qualitatively follows the previous findings based on general circulation models (GCMs), but with a detailed dynamical mechanism in linkage between the lower‐ and upper‐atmospheric circulation in the regional climate modelling (RCM) framework in this study. Copyright © 2009 Royal Meteorological Society
Rules of engagement in turbulent times: How Verizon Wireless uses a robust HR portal for employee communication
Authors: Poglianich Antonio , Antonek Matt
Published: April 2009

Turbulent times such as these will test the resilience of many companies' communication capabilities, particularly for rapid response with consistent messaging to focus and engage a wary and distracted workforce on the many challenges ahead. The answer may be an HR portal like that at Verizon Wireless, where it is a core part of an engagement strategy that is the envy of the industry. The article discusses the importance of engagement for organizational and business performance; the role communication can play in driving engagement; and five principles for accomplishing this. The article goes on to explore how Verizon Wireless has developed and positioned its HR portal for rapid as well as sustained messaging, personalization, and self‐service tools that all help define the employee experience. © 2009 Wiley Periodicals, Inc.
Creating growth with externalization of R&D results—the spin‐along approach
Authors: Rohrbeck René , Döhler Mario , Arnold Heinrich
Published: April 2009

After a long period of restructuring and outsourcing, companies are increasingly looking for new growth opportunities. Growth with existing products or by expansion in new markets is limited. Therefore, companies are searching for ways to expand their activities in new businesses. A frequently used tool of multinational enterprises is corporate venturing. Within corporate venturing, a further differentiation can be made between internal venturing and external venturing. Internal venturing promotes business ideas generated within the organization, whereas external venturing integrates business ideas developed outside the company.

This article presents a special case of corporate venturing: the spin‐along approach of Deutsche Telekom Laboratories. It can be seen as a combination of internal and external venturing. In the spin‐along approach, employees of the corporate research and development (R&D) department are encouraged to take their technology or business idea external by founding a separate company. Successful companies might later be bought and integrated back into Deutsche Telekom. © 2009 Wiley Periodicals, Inc.
Formation of cartilage repair tissue in articular cartilage defects pretreated with microfracture and covered with cell‐free polymer‐based implants
Authors: Erggelet Christoph , Endres Michaela , Neumann Katja , Morawietz Lars , Ringe Jochen , Haberstroh Kathrin , Sittinger Michael , Kaps Christian
Published: April 2009

The aim of our study was to evaluate the mid‐term outcome of a cell‐free polymer‐based cartilage repair approach in a sheep cartilage defect model in comparison to microfracture treatment. Cell‐free, freeze‐dried implants (chondrotissue®) made of a poly‐glycolic acid (PGA) scaffold and hyaluronan were immersed in autologous serum and used for covering microfractured full‐thickness articular cartilage defects of the sheep (n = 4). Defects treated with microfracture only served as controls (n = 4). Six months after implantation, cartilage implants and controls were analyzed by immunohistochemical staining of type II collagen, histological staining of proteoglycans, and histological scoring. Histological analysis showed the formation of a cartilaginous repair tissue rich in proteoglycans. Histological scoring documented significant improvement of repair tissue formation when the defects were covered with the cell‐free implant, compared to controls treated with microfracture. Immunohistochemistry showed that the cell‐free implant induced cartilaginous repair tissue and type II collagen. Controls treated with microfracture showed marginal formation of a mixed‐type repair tissue consisting of cartilaginous tissue and fibro‐cartilage. Covering of microfractured defects with the cell‐free polymer‐based cartilage implant is suggested to be a promising treatment option for cartilage defects and improves the regeneration of articular cartilage. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27:1353–1360, 2009
CD44 deficiency improves healing tendon mechanics and increases matrix and cytokine expression in a mouse patellar tendon injury model
Authors: Ansorge Heather L. , Beredjiklian Pedro K. , Soslowsky Louis J.
Published: April 2009

CD44 plays an important role in inflammation and healing. Previous studies investigated its role in inflammatory diseases and skin wounds; however, the role of CD44 in tendon healing is unknown. Therefore, we investigated the effect of CD44 in the healing of the patellar tendon in a knockout mouse model. We hypothesized that in comparison to wild‐type counterparts, CD44 knockout mice would have decreased material parameters, increased organization, decreased expression of proinflammatory cytokines, and increased expression of matrix components during healing. These hypotheses were tested through an in vivo surgical model and mechanical, organizational, and gene expression analyses. Material strength and tissue organization were significantly improved in the CD44 knockout mouse. This could be attributed to increased expression of cytokines and matrix components that are also elevated in regenerative healing. Our study showed that the absence of CD44 in a mouse patellar tendon injury creates an environment that is conducive to regenerative healing through altered gene expression, resulting in superior material properties and reduced cross‐sectional area. Therefore, limiting the role of CD44 may improve healing parameters in adult tendon injury. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27:1386–1391, 2009
Material properties are related to stress fracture callus and porosity of cortical bone tissue at affected and unaffected sites
Authors: Entwistle Rachel C. , Sammons Sara C. , Bigley Robert F. , Hazelwood Scott J. , Fyhrie David P. , Gibeling Jeffery C. , Stover Susan M.
Published: April 2009

Stress fractures are overuse injuries of bone that affect elite athletes and military recruits. One response of cortical bone to stress fracture is to lay down periosteal callus. The objectives of this study were to determine if material properties are different among bones with different stages of stress fracture callus, at both a callus site and at a distal site. Cortical specimens were mechanically tested to determine their stress–strain response. Material property differences were examined using nonparametric and regression analyses. At the callus site, material properties were low during the earliest stages of callus, higher with increasing callus maturity, but dropped at the late stage of callus. At the distal site, the material properties were low during early stages of callus and approached, or returned to, those of bones without callus during the late stages of callus. The effects of stress fracture and bone callus are not limited to the focal site of stress fracture. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27:1272–1279, 2009
The effect of rapamycin on bone growth in rabbits
Authors: Phornphutkul Chanika , Lee Mark , Voigt Cliff , Wu Ke‐Ying , Ehrlich Michael G. , Gruppuso Philip A. , Chen Qian
Published: April 2009

mTOR is a nutrient‐sensing protein kinase that regulates numerous cellular processes. Our prior studies using the mTOR inhibitor, rapamycin, indicate an important role for mTOR in chondrogenesis. We extended our observations to a physiological, in vivo model of bone growth, direct infusion of rapamycin into the proximal tibial growth plates of rabbits. Rapamycin or DMSO vehicle was infused directly into growth plates by an osmotic minipump for 8 weeks. Tibial growth was followed radiographically. At the end of the experiment, growth plates were recovered for histological analysis. Six animals were studied. No untoward effects of rapamycin infusion were found. Bone growth of limbs exposed to rapamycin was slower than control limbs, particularly during the period of most rapid growth. Histological analysis revealed that growth plate height in the rapamycin‐infused limbs was reduced. Both the hypertrophic and proliferative zones were significantly smaller in the rapamycin‐infused limbs. Direct infusion of rapamycin into proximal tibial growth plates decreased the size of the growth plate and inhibited overall long bone growth. Rapamycin appears to affect both the proliferative and hypertrophic zones of the tibial growth plate. Our results indicate that nutrients may exert a direct effect on long bone growth via mTOR‐mediated modulation of chondrogenesis at the growth plate. and suggest that the possible inhibitory effects of rapamycin on skeletal growth warrant further attention before its use in children. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res
In defence of the meltwater (megaflood) hypothesis for the formation of subglacial bedform fields
Authors: Shaw John
Published: April 2009

Characteristics of large‐scale fluting and hummocky terrain on the Canadian Prairies test glacial and meltwater hypotheses for landform genesis. These tests defend the meltwater model. Neither sedimentary nor glaciotectonic processes can fully explain such erosional landforms. Province‐scale flow paths, which mark palaeo‐ice streams and subglacial flood routes, contain large‐scale fluting with flanking hummock terrain. Antecedent relief causes these paths to differ from other flood landscapes such as the Scablands. Proponents of the glacial hypothesis use an invalid analogy between Icelandic and Prairie landsystems. They suggest that groove‐ploughing formed large‐scale fluting, and that ice pushing created hummocky terrain. However, landform location, form, and extent, surface lags, truncated architecture, and landform associations favour the meltwater hypothesis. A simple thought experiment and clear understanding of the principle of least number of assumptions answer the criticisms that meltwater forms cannot cross‐cut and that the meltwater hypothesis disregards proper hypothesis testing. An example of cross‐cutting erosional marks supports this theory. No narrow tract of smoothed terrain with fluting terminates at the glacially thrust Neutral Hills, negating an important point in the glacial hypothesis. While neither the glacial hypothesis nor postglacial winnowing explain boulder and cobble lags with percussion marks, meltwater processes explain them well. Copyright © 2009 John Wiley & Sons, Ltd.
Reconstruction of the East China Sea palaeoenvironment at 16 ka by comparison of fossil and modern Faviidae corals from the Ryukyus, southwestern Japan
Authors: Mishima Mari , Kawahata Hodaka , Suzuki Atsushi , Inoue Mayuri , Okai Takashi , Omura Akio
Published: April 2009

We conducted paired measurements of the Sr/Ca ratio and oxygen and carbon stable isotopes of a fossil Faviidae coral specimen (MYK90), age 16 ka, collected from near Miyako Island, the Ryukyus, southwestern Japan. Our study aimed to reconstruct the palaeoenvironment in the East China Sea at 16 ka by comparing the fossil sample with modern Faviidae corals. Our data with annual or longer time resolution may be very suitable for palaeoceanographic reconstruction, although no general calibration method for Faviidae corals has been reported. Our calibration showed that the annual mean sea surface temperature was approximately 5°C lower and sea surface salinity (SSS) at the study site was locally higher at 16 ka than at present. Even though the mouths of the Yellow and Changjiang rivers were east of their present locations because sea level was much lower, our results suggest that the influence of the terrestrial water discharge may not have extended to Miyako Island. Weak summer monsoon activity during the last glacial, which decreased summer precipitation over the Asian continent, and an enhanced winter monsoon, which may have led to more evaporation, likely contributed to the inferred high SSS at the study site. Copyright © 2009 John Wiley & Sons, Ltd.
Temperature‐dependent Raman spectra of Ba2BiSbO6 ceramics
Authors: Castro Manoel Carvalho , Carvalho Edson Firmino Viana , Paraguassu Waldeci , Ayala Alejandro Pedro , Snyder Frank C. , Lufaso Michael W. , Paschoal Carlos William de Araujo
Published: April 2009

In this work, we have performed Raman scattering measurements in Ba2BiSbO6 ceramics in the temperature range from 10 to 573 K. The Raman spectra were examined using group theory to analyze the decomposition of the reducible representation of the vibrational modes and with a virtual octahedral model. At room temperature, five modes were observed. At low temperatures, the spectra subtly showed the rhombohedral–monoclinic phase transition, which was identified by changes in the Raman intensity of the bending and symmetrical stretching SbO6 octahedral modes. The cubic–rhombohedral phase transition was not clearly evident in the high‐temperature Raman data. Copyright © 2009 John Wiley & Sons, Ltd.
Lineshape analysis of stimulated Raman spectra of the near‐nozzle region of free jet expansions
Authors: Ramos Ángel , Santos Julio , Abad Laura , Bermejo Dionisio , Herrero Víctor J. , Tanarro Isabel
Published: April 2009

An anomalous lineshape of stimulated Raman spectra obtained from the region very close to the nozzle of supersonic pulsed expansions of nitrogen is presented. High‐resolution Raman spectra of the Q branch of the fundamental vibration mode of N2 have been recorded from two different nitrogen expansions at T0 = 295 K and P0 = 1.5–3.5 bar, the lasers crossing the jet axis in the range z/D = 0.25–1.25, where D is the effective nozzle diameter. The combination of Doppler shifts and strong gradients of density and temperature in the near‐nozzle region yield an inhomogeneous broadening and a double peak structure of the recorded Raman line profiles. The comparison of the experimental results with the simulation of the Raman spectrum from this region provides valuable information about the near‐nozzle flow field. The lineshape described here is different from another reported previously in the literature, which is based on a depletion of the density of free molecules on the axis due to condensation. Copyright © 2009 John Wiley & Sons, Ltd.
Raman spectroscopy of Cu doping in Zn1−xCoxO diluted magnetic semiconductor
Authors: Hoang Luc Huy , Hien Nguyen Thi Minh , Hai Nguyen Hoang , Hai Pham Van , Khoi Nguyen The , Yang In‐Sang
Published: April 2009

The room‐temperature ferromagnetism and the Raman spectroscopy of the Cu‐doped Zn1−xCoxO powders prepared by the sol–gel method are reported. The x‐ray diffraction (XRD) data confirmed that the wurtzite structure of ZnO is maintained for ZnO doped with Co below 10 at%. The magnetization–field curves measured at room temperature demonstrated that all Co‐doped ZnO powders were paramagnetic. Ferromagnetic ordering is observed for the samples doped with Cu in Zn0.98Co0.02O and strongly depends on the concentration of Cu. The relative strength of the second‐order LO peak to the first‐order one in the Raman spectra, which is related to the carrier concentration, of the Cu‐doped Zn0.98Co0.02O powder is strongly correlated with the saturation magnetic moment of the system. This seems to be in favor of the Ruderman‐Kittel‐Kasuya‐Yosida (RKKY) or double exchange mechanism of the ferromagnetism in this system. Copyright © 2009 John Wiley & Sons, Ltd.
Towards a rational drug design: Raman micro‐spectroscopy analysis of prostate cancer cells treated with an aqueous extract of Nerium Oleander
Authors: Saha A. , Yakovlev V. V.
Published: April 2009

Raman spectroscopy is an efficient optical technique used to identify and grade cancer on the basis of the molecular composition of the cell. In this work Raman spectroscopy is used to study the chemical alteration occurring inside a prostate cancer cell as a result of a treatment with a low‐concentration aqueous extract of Nerium Oleander. The results show that Nerium Oleander affects the protein and lipid concentration of cancer cells. Copyright © 2009 John Wiley & Sons, Ltd.
Microstructural characteristics and corrosion property of non‐chromate surface treatments on AZ91D magnesium alloy
Authors: Chen B. , Li Q. , Gao H. , Fan J. M. , Tan X.
Published: April 2009

Chromate conversion coatings can be successfully used for corrosion protection of magnesium alloys. However, the environmental laws have imposed severe restrictions on chromate use in many countries. In this study, a novel protective environmental‐functionally gradient coating was formed on AZ91D magnesium alloy by non‐chromate surface treatments, which consisted of pre‐etching followed by cerium‐based chemical conversion before applying the sol–gel CeO2 film. It was determined by the analysis of X‐ray diffraction that the gradient coating was mainly composed of CeO2. The calculation, based on the Scherrer formula, further revealed the formation of nanocrystalline structure in the coating. Scanning electron microscopy (SEM) observations showed that the coating was homogeneous and compact, no obvious cracked structure occurred. According to the immersion tests, potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS) tests, the corrosion resistance of AZ91D magnesium alloy was found to be greatly improved by means of this novel environmental‐functionally gradient coating.
Maleimide Functionalized Poly(ε‐caprolactone)‐block‐poly(ethylene glycol) (PCL‐PEG‐MAL): Synthesis, Nanoparticle Formation, and Thiol Conjugation
Authors: Ji Shengxiang , Zhu Zhengxi , Hoye Thomas R. , Macosko Christopher W.
Published: April 2009

Carboxylic acid terminated poly(ε‐caprolactone)s (PCL‐COOHs) with narrow polydispersity were synthesized and coupled with poly(ethylene glycol) (HO–PEG–OH) to afford PCL‐PEG–OH copolymers. The hydroxyl groups in the PCL‐PEG–OHs were then converted to maleimide groups to afford maleimide terminated PCL‐PEG‐MALs that contained 70–90% maleimide functionality. Nanoparticles with maleimide functionality on their surfaces were prepared by impingement mixing. Particle sizes and size distributions were determined by dynamic light scattering. Conjugation of reduced glutathione with model maleimides and two MAL‐functional nanoparticles was also demonstrated. The amount of accessible maleimide on the particle surface was measured using Ellman's reagent to range between ≈51–67%.

magnified image
Synthesis and Characterization of Block Copolymers of Polyoxyethylene and Polylactide with Different Architectures
Authors: Mai Shao‐min , Abbot Annie , Norton David , McKean Robert , Ryan Anthony J.
Published: April 2009

Diblock and triblock copolymers were prepared from polyethylene glycol (PEG, $\overline M _{\rm n}$ = 2 000), L‐lactide and D,L‐lactide. A novel method was developed to prepare high‐molecular‐weight multiblock copolymers by transesterification of a PEG/succinic acid polyester with poly(L‐lactide). Molecular weights were monitored by GPC and overall composition was checked by 1H NMR. Crystallinity, bulk microstructure, and the glass transition were investigated by DSC and simultaneous SAXS/WAXS/DSC, and surface properties by measurement of advancing contact angle. It is found that the crystallization of the poly(ethylene oxide) (PEO) block is very much affected by the position of the PEO block in the copolymer and by the length and the state of the polylactide block. Both DSC and WAXS showed that the crystallization of PEG2000 block was very much suppressed when covalently bonding to polylactide (PLA) blocks. These methods also confirmed good miscibility between amorphous PLA and PEG blocks. The preparation of fiber by electrospinning demonstrates the target application of the multiblock copolymers in tissue engineering.

magnified image
Microstructure and Molecular Interaction in Glycerol Plasticized Chitosan/Poly(vinyl alcohol) Blending Films
Authors: Liang Songmiao , Huang Qingrong , Liu Linshu , Yam Kit L.
Published: April 2009

Exploring some basic interactions in blending systems is of great significance for designing a blend with controlled structure and properties. This work attempts to analyze microstructure and molecular interaction in glycerol plasticized chitosan/poly(vinyl alcohol) blends by atomic force microscopy, differential scanning calorimetry and ATR‐FTIR spectroscopy. Our results show that the blending films are aggregated by spherical chitosan/poly(vinyl alcohol) blending nanoparticles. The size and aggregation behavior of these particles are closely related to glycerol content. The presence of glycerol gives rise to a continuous closing in Tg of poly(vinyl alcohol) and chitosan components, suggesting an improved miscibility of the blend. Strong hydrogen bonding interaction in the blend is observed and further distinguished by peak resolution. Moreover, more interesting evidence on the effect of glycerol in the blends is provided by monitoring the structure evolution of the blend at different blending steps using atomic force microscopy. The formation of strong hydrogen bonding network among glycerol molecules and polymer matrix was considered as the main driving force to result in the changes in the microstructure and miscibility of the blend.

magnified image
Distribution conventionality in the movie sector: an econometric analysis of cinema supply
Authors: Collins Alan , Scorcu Antonello E. , Zanola Roberto
Published: April 2009

This paper empirically analyzes the impact of several factors on a ‘conventionality index (CI)’ in the specific context of the cinema exhibition sector. To our knowledge, it is the first time that a standard CI has been constructed for this purpose. Econometric analysis of the determinants of variation in this index provides decision‐makers with an empirical focus for analyzing distributional aspects of the movie exhibition market, with particular emphasis on product differentiation. Specifically, (i) do cinemas based in a city area have a different or ‘specialized’ focus in contrast to cinemas in small towns? or (ii) do multiplexes have a different or more specialized focus in comparison with cinemas? To this end, cross‐sectional econometric models are estimated to help analyze these effects in three Italian regions for a sample of cinemas covering the 2006 season. Copyright © 2009 John Wiley & Sons, Ltd.
Status of groundwater arsenic contamination in the state of West Bengal, India: A 20‐year study report
Authors: Chakraborti Dipankar , Das Bhaskar , Rahman Mohammad Mahmudur , Chowdhury Uttam Kumar , Biswas Bhajan , Goswami A. B. , Nayak Bishwajit , Pal Arup , Sengupta Mrinal Kumar , Ahamed Sad , Hossain Amir , Basu Goutam , Roychowdhury Tarit , Das Dipankar
Published: April 2009

Since 1988 we have analyzed 140 150 water samples from tube wells in all 19 districts of West Bengal for arsenic; 48.1% had arsenic above 10 μg/L (WHO guideline value), 23.8% above 50 μg/L (Indian Standard) and 3.3% above 300 μg/L (concentration predicting overt arsenical skin lesions). Based on arsenic concentrations we have classified West Bengal into three zones: highly affected (9 districts mainly in eastern side of Bhagirathi River), mildly affected (5 districts in northern part) and unaffected (5 districts in western part). The estimated number of tube wells in 8 of the highly affected districts is 1.3 million, and estimated population drinking arsenic contaminated water above 10 and 50 μg/L were 9.5 and 4.2 million, respectively. In West Bengal alone, 26 million people are potentially at risk from drinking arsenic‐contaminated water (above 10 μg/L). Studying information for water from different depths from 107 253 tube wells, we noted that arsenic concentration decreased with increasing depth. Measured arsenic concentration in two tube wells in Kolkata for 325 and 51 days during 2002–2005, showed 15% oscillatory movement without any long‐term trend. Regional variability is dependent on sub‐surface geology. In the arsenic‐affected flood plain of the river Ganga, the crisis is not having too little water to satisfy our needs, it is the crisis of managing the water.
Arsenic speciation in cattail (Typha latifolia) using chromatography and mass spectrometry
Authors: Lu Xiufen , Nguyen Nena , Gabos Stephan , Le X. Chris
Published: April 2009

Typha latifolia, commonly known as cattail, is widely used as traditional food and medicinal ingredients by indigenous people. There have been concerns over the high levels of total arsenic in cattail plants, but the chemical species of arsenic in cattail have not been characterized. We describe here the determination of arsenic species in the various compartments of cattail. Average concentrations of total arsenic from 9 to 19 cattail plants were 1120 μg/kg (range 68–2600 μg/kg) in the fine (hairy) roots, 575 μg/kg (range 16–1400) in the skin of tuber, 26 μg/kg (range 2–82) in the core of the tuber, 6 μg/kg (range 5–12) in the stem, and 420 μg/kg (range 4–1970) in the whole tuber. Speciation analysis using strong anion exchange, ion pairing, and strong cation exchange chromatography separation with MS detection revealed the presence of inorganic arsenite, arsenate, dimethylarsinic acid, and monomethylarsonic acid. The two inorganic arsenic species accounted for >80% of the total arsenic. Further analyses of arsenic and iron concentrations showed a strong correlation between arsenic and iron in the fine roots and skin. These results suggest that arsenic and iron are colocalized (codeposited) in the skin of the cattail plants, consistent with the previous findings. The level of exposure to arsenic from the use of cattail as food and medicine can be substantially reduced by removing the skin of cattail.
Impact of arsenic on nucleotide excision repair: XPC function, protein level, and gene expression
Authors: Nollen Maike , Ebert Franziska , Moser Jill , Mullenders Leon H. F. , Hartwig Andrea , Schwerdtle Tanja
Published: April 2009

The ubiquitous occurrence of the human carcinogen arsenic results in multiple exposure possibilities to humans. The human diet, especially drinking water, is the primary source of inorganic arsenic intake in the general population. The ingested arsenic is metabolized to methylated derivatives; some of these metabolites are today considered to be more toxic than the inorganic species. Various modes of action have been proposed to contribute to arsenic carcinogenicity; inhibition of nucleotide excision repair (NER), removing DNA helix distorting DNA adducts induced by environmental mutagens, is likely to be of primary importance. Here, we report that arsenite and its metabolite monomethylarsonous acid (MMA(III)) strongly decreased expression and protein level of Xeroderma pigmentosum complementation group C (XPC), which is believed to be the principle initiator of global genome NER. This led to diminished association of XPC to sites of local UVC damage, resulting in decreased recruitment of further NER proteins. Additionally Xeroderma pigmentosum complementation group E protein (XPE) expression was reduced, which encodes for another important NER protein and similarly to XPC is regulated by the activity of the transcription factor p53. In summary, our data demonstrate that in human skin fibroblasts arsenite and even more pronounced MMA(III) interact with XPC expression, resulting in decreased XPC protein level and diminished assembly of the NER machinery.
A DFT and AIM analysis of the spin–spin couplings across the hydrogen bond in the 2‐fluorobenzamide and related compounds
Authors: Alkorta Ibon , Elguero José , Limbach Hans‐Heinrich , Shenderovich Ilja G. , Winkler Tammo
Published: April 2009

In 1975 a large number of coupling constants were measured in 2‐fluorobenzamide labeled with15N. Some of them were assigned to couplings through intramolecular NH···F hydrogen bonds (HBs). These couplings change dramatically when CDCl3is replaced by DMSO‐d6. In this theoretical paper we provide density functional theory (DFT) calculations that justify the existence of a weak HB in the absence of solvent, while solvents that act as HB acceptors break down the intramolecular hydrogen bond (IMHB) of 2‐fluorobenzamide. Atoms in molecules (AIM) analyses and Steiner‐Limbach plots were used to analyze the structure of the compounds. Copyright © 2009 John Wiley & Sons, Ltd.
Development of functional LH Receptors on pig cumulus–oocyte complexes cultured in vitro by a novel two‐step culture system
Authors: Procházka Radek , Nĕmcová Lucie , Nagyová Eva , Scsuková Son̆a , Mlynarc̆íková Alz̆beta
Published: April 2009

We show in the present study that freshly isolated pig cumulus–oocyte complexes (COCs) display a limited response to LH, as assessed by the expression of hyaluronan synthase 2 (Has2) mRNA, activation of protein kinase A (PKA), production of hyaluronic acid (HA) and progesterone, cumulus cell expansion and resumption of meiosis. These data indicate that freshly isolated COCs do not possess a sufficient number of functional LH receptors (LHR). However, the expression of Lhr significantly increased during the culture of COCs in vitro in a medium supplemented with FSH. Assuming that the effect of FSH on LHR induction is mediated via cAMP signaling pathways, we developed a new culture system, in which the COCs were pre‐cultured for 72 hr in a medium supplemented with dbcAMP. The pre‐cultured COCs remained in the germinal vesicle stage, their cumulus investment underwent a dramatic increase in size and gap junctions between the cumulus cells were preserved. The stimulation of such COCs with either FSH or LH led to the resumption and completion of meiosis, activation of PKA, expression of Has2, synthesis of large amounts of HA and progesterone, and extensive expansion of cumulus cells. We conclude that the formation of functional LHR is stimulated in cumulus cells during the culture in vitro in a cAMP‐dependent pathway. The dbcAMP‐treated COCs thus represent a new model in which the resumption of meiosis and cumulus expansion can be induced exclusively by the action of recombinant LH. Mol. Reprod. Dev. 76: 751–761, 2009. © 2009 Wiley‐Liss, Inc.
Methodology for Kinetic Modeling of Atom Transfer Radical Polymerization
Authors: D'hooge Dagmar R. , Reyniers Marie‐Françoise , Marin Guy B.
Published: April 2009

A methodology for kinetic modeling of atom transfer radical polymerization is developed allowing to calculate the monomer conversion, the fraction of polymer molecules having end group functionality, the full molar mass distribution (MMD) of the dormant polymer and the number, mass, and z based average molar mass of the dead and dormant polymer. The developed methodology is based on an extension of the method of moments and allows an accurate description of the contribution of the polymer molecules with a high molar mass to the MMD of the polymer. Diffusional limitations on all considered reaction steps are systematically accounted for. Simulation results are in good agreement with experimental observations. Moreover, the methodology allows a detailed description of the broadness and the skewness of the MMD of the polymer.

magnified image
Gradient Copolymers by ATRP in Semibatch Reactors: Dynamic Monte Carlo Simulation
Authors: Al‐Harthi Mamdouh , Khan Masihullah J. , Abbasi Sarfraz H. , Soares João B. P.
Published: April 2009

We developed a dynamic Monte Carlo model for ATRP in semibatch reactors. Semibatch reactors can be used to produce gradient copolymers even if the difference between the reactivity ratios of the comonomers is not significant by using different comonomer feed policies. The model was used to predict average molecular weights, polydispersity index, copolymer composition and complete distributions of molecular weight, chemical composition, and comonomer sequence length at any polymerization time. Two case studies, poly[styrene‐co‐(methyl methacrylate)] and poly[acrylonitrile‐co‐(methyl methacrylate)], were chosen to demonstrate the effect of comonomer feed compositions on the final chemical composition distribution of the copolymer.

magnified image