bluuebunny/crossref_metadata_2025 huggingface dataset:
Differential effect of NR2A and NR2B subunit selective NMDA receptor antagonists on striato‐pallidal neurons: relationship to motor response in the 6‐hydroxydopamine model of parkinsonism
Authors: Fantin Martina , Auberson Yves P. , Morari Michele
Published: April 2008

We previously demonstrated that NMDA receptors containing the NR2A or NR2B subunits differentially regulate striatal output pathways. We now investigate whether such a differential control is altered under parkinsonian conditions and whether subunit selective antagonists have different abilities to attenuate parkinsonian‐like motor deficits. Three microdialysis probes were simultaneously implanted in the dopamine‐depleted striatum, globus pallidus and substantia nigra reticulata of 6‐hydroxydopamine hemilesioned rats. The NR2A antagonist NVP‐AAM077 perfused in the striatum reduced pallidal GABA, but not glutamate, levels whereas the NR2B antagonist Ro 25‐6981 was ineffective. Neither antagonist affected striatal or nigral amino acid levels. To investigate whether these neurochemical responses were predictive of different antiparkinsonian activities, antagonists were administered systemically and motor activity evaluated in different motor tasks. Neither antagonist attenuated akinesia/bradykinesia in the bar and drag test. However, NVP‐AAM077 dually modulated rotarod performance (low doses being facilitatory and higher ones inhibitory) while Ro 25‐6981 monotonically improved it. Microdialysis revealed that motor facilitating doses reduced pallidal GABA levels while motor inhibiting doses increased them. We conclude that, under parkinsonian conditions, the striato‐pallidal pathway is driven by striatal NR2A subunits. Motor improvement induced by NVP‐AAM077 and Ro 25‐6981 is accomplished by blockade of striatal NR2A and extrastriatal NR2B subunits, respectively.
Partial inhibition of complex I activity increases Ca2+‐independent glutamate release rates from depolarized synaptosomes
Authors: Kilbride Seán M. , Telford Jayne E. , Tipton Keith F. , Davey Gavin P.
Published: April 2008

Mitochondria have been implicated in the pathogenesis of several neurodegenerative disorders and, in particular, complex I (NADH:ubiquinone oxidoreductase, EC 1.6.5.3) activity has been shown to be partially reduced in postmortem studies of the substantia nigra of Parkinson’s disease patients. The present study examines the effect of partial inhibition of complex I activity on glutamate release from rat brain synaptosomes. Following a 40% inhibition of complex I activity with rotenone, it was found that Ca2+‐independent release of glutamate increased from synaptosomes depolarized with 4‐aminopyridine. Highest rates of glutamate release were found to occur between 60–90% complex I inhibition. A similar pattern of increase was shown to occur in synaptosomes depolarized with KCl. The increase in glutamate release was found to correlate to a significant decrease in ATP. Inhibition of complex I activity by 40% was also shown to cause a significant collapse in mitochondrial membrane potential (Δψm). These results suggest that partial inhibition of complex I activity in in situ mitochondria is sufficient to significantly increase release of glutamate from the pre‐synaptic nerve terminal. The relevance of these results in the context of excitotoxicity and the pathogenesis of neurodegenerative disorders is discussed.
Conformational change of the transmembrane helices II and IV of metabotropic glutamate receptor involved in G protein activation
Authors: Yamashita Takahiro , Terakita Akihisa , Kai Toshihiro , Shichida Yoshinori
Published: April 2008

G protein‐coupled receptors are classified into several families on the basis of their amino acid sequences and the members of the same family exhibit sequence similarity but those of different families do not. In family 1 GPCRs such as rhodopsin and adrenergic receptor, extensive studies have revealed the stimulus‐dependent conformational change of the receptor: the rearrangement of transmembrane helices III and VI is essential for G protein activation. In contrast, in family 3 GPCRs such as metabotropic glutamate receptor (mGluR), the inter‐protomer relocation upon ligand binding has been observed but there is much less information about the structural changes of the transmsmbrane helices and the cytoplasmic domains. Here we identified constitutively active mutation sites at the cytoplasmic borders of helices II and IV of mGluR8 and successfully inhibited the G protein activation ability by engineering disulfide cross‐linking between these cytoplasmic regions. The analysis of all possible single substitution mutants of these residues revealed that some steric interactions around these sites would be important to keep the receptor protein inactive. These results provided the model that the conformational changes at the cytoplasmic ends of helices II and IV of mGluR are involved in the efficient G protein coupling.
A Follow‐up Study of Characteristics of Young People that Dropout and Continue Psychotherapy: Service Implications for a Clinic in the Community
Authors: Baruch Geoffrey , Vrouva Ioanna , Fearon Pasco
Published: April 2008

Background:  The paper reports the findings from a follow‐up study of the factors that contribute to whether young people dropout or continue once‐weekly psychotherapy at a voluntary sector psychotherapy service for young people aged 12 to 21 years.

Method:  The study uses data from an ongoing audit of the psychotherapy service that started in 1993; 882 young people were included in the study. Premature termination of treatment was defined as dropping out before the 21st session. Continuation in treatment was defined as remaining in therapy after 20 sessions. Measures and areas of interest used in the study include diagnostic measures, the Youth Self Report Form and Young Adult Self Report Form, demographic characteristics and treatment related information.

Results:  Young people who continued in treatment were more likely to be older, have anxieties about sexual and relationship issues and have higher scores on self‐reported anxiety‐depression. Young people who dropped out of treatment were more likely to be younger, have higher self‐reported delinquency scores, have a diagnosis of hyperactivity‐conduct disorder and be homeless.

Conclusions:  The study of treatment termination has demonstrated the value of service audit and has led to a significant change in clinical practice.
Being here and there: in‐betweeness, double absence, and the making of a multi‐layered academic citizenship
Authors: Rossi Ugo
Published: April 2008

In this commentary I contribute to the ongoing debate about changing conditions of academic labour by sharing my personal experience as a fixed‐term scholar dealing with an in‐between positionality within the academia. This intervention is intended, on the one hand, to shed light on the condition of an increasing number of early career geographers today, which has not been highlighted by the literature so far; on the other hand, it pursues the more ambitious goal of providing reflections on the potential of a multi‐layered academic citizenship in contemporary Europe.
Effects of Artificial Roosts for Frugivorous Bats on Seed Dispersal in a Neotropical Forest Pasture Mosaic
Authors: KELM DETLEV H. , WIESNER KERSTIN R. , HELVERSEN OTTO von
Published: April 2008

Abstract:  In the Neotropics ongoing deforestation is producing open and heavily fragmented landscapes dominated by agriculture, mostly plantations and cattle pastures. After some time agriculture often becomes uneconomical and land is abandoned. Subsequent habitat regeneration may be slow because seed inputs are restricted by a lack of incentives—such as suitable roost sites—for seed dispersers to enter deforested areas. Increasing environmental awareness has fostered growing efforts to promote reforestation. Practical and cost‐efficient methods for kick‐starting forest regeneration are, however, lacking. We investigated whether artificial bat roosts for frugivorous bat species can attract these key seed dispersers to deforested areas, thereby increasing seed rain. We installed artificial bat roosts in a forest‐pasture mosaic in the Costa Rican Atlantic lowlands and monitored bat colonization and seed dispersal. Colonization occurred within a few weeks of installation, and 10 species of bats occupied the artificial roosts. Five species of frugivorous or nectarivorous bats colonized artificial roosts permanently in both primary habitat and in deforested areas, in numbers similar to those found in natural roosts. Seed input around artificial roosts increased significantly. Sixty‐nine different seed types, mostly of early‐successional plant species, were transported by bats to artificial roosts in disturbed habitats. The installation of artificial bat roosts thus successfully attracted frugivorous bats and increased seed inputs into degraded sites. This method is likely to speed up early‐vegetation succession, which in turn will attract additional seed dispersers, such as birds, and provide a microhabitat for seeds of mid‐ and late‐successional plants. As well as supporting natural forest regeneration and bat conservation, this cost‐efficient method can also increase environmental awareness among landowners.
Current Trends in Plant and Animal Population Monitoring
Authors: MARSH DAVID M. , TRENHAM PETER C.
Published: April 2008

Abstract:  Animal and plant population monitoring programs are critical for identifying species at risk, evaluating the effects of management or harvest, and tracking invasive and pest species. Nevertheless, monitoring activities are highly decentralized, which makes it difficult for researchers or conservation planners to get a good general picture of what real‐world monitoring programs actually entail. We used a Web‐based survey to collect information on population monitoring programs. The survey focused on basic questions about each program, including motivations for monitoring, types of data being collected, spatiotemporal design of the program, and reasons for choosing that design. We received responses from 311 people involved in monitoring of various species and used these responses to summarize ongoing monitoring efforts. We also used responses to determine whether monitoring strategies have changed over time and whether they differed among monitoring agencies. Most commonly, monitoring entailed collection of count data at multiple sites with the primary goal of detecting trends. But we also found that goals and strategies for monitoring appeared to be diversifying, that area‐occupied and presence–absence approaches appeared to be gaining in popularity, and that several other promising approaches (monitoring to reduce parameter uncertainty, risk‐based monitoring, and directly linking monitoring data to management decisions) have yet to become widely established. We suggest that improved communication between researchers studying monitoring designs and those who are charged with putting these designs into practice could further improve monitoring programs and better match sampling designs to the objectives of monitoring programs.
Synchronous peak Barrovian metamorphism driven by syn‐orogenic magmatism and fluid flow in southern Connecticut, USA
Authors: LANCASTER P. J. , BAXTER E. F. , AGUE J. J. , BREEDING C. M. , OWENS T. L.
Published: April 2008

Recent work in Barrovian metamorphic terranes has found that rocks experience peak metamorphic temperatures across several grades at similar times. This result is inconsistent with most geodynamic models of crustal over‐thickening and conductive heating, wherein rocks which reach different metamorphic grades generally reach peak temperatures at different times. Instead, the presence of additional sources of heat and/or focusing mechanisms for heat transport, such as magmatic intrusions and/or advection by metamorphic fluids, may have contributed to the contemporaneous development of several different metamorphic zones. Here, we test the hypothesis of temporally focussed heating for the Wepawaug Schist, a Barrovian terrane in Connecticut, USA, using Sm–Nd ages of prograde garnet growth and U–Pb zircon crystallization ages of associated igneous rocks. Peak temperature in the biotite–garnet zone was dated (via Sm–Nd on garnet) at 378.9 ± 1.6 Ma (2σ), whereas peak temperature in the highest grade staurolite–kyanite zone was dated (via Sm–Nd on garnet rims) at 379.9 ± 6.8 Ma (2σ). These garnet ages suggest that peak metamorphism was pene‐contemporaneous (within error) across these metamorphic grades. Ion microprobe U–Pb ages for zircon from igneous rocks hosted by the metapelites also indicate a period of syn‐metamorphic peak igneous activity at 380.6 ± 4.7 Ma (2σ), indistinguishable from the peak ages recorded by garnet. A 388.6 ± 2.1 Ma (2σ) garnet core age from the staurolite–kyanite zone indicates an earlier episode of growth (coincident with ages from texturally early zircon and a previously published monazite age) along the prograde regional metamorphic T–t path. The timing of peak metamorphism and igneous activity, as well as the occurrence of extensive syn‐metamorphic quartz vein systems and pegmatites, best supports the hypothesis that advective heating driven by magmas and fluids focussed major mineral growth into two distinct episodes: the first at c. 389 Ma, and the second, corresponding to the regionally synchronous peak metamorphism, at c. 380 Ma.
INTER‐ AND INTRASPECIFIC COMMUNITY STRUCTURE WITHIN THE DIATOM GENUS PSEUDO‐NITZSCHIA (BACILLARIOPHYCEAE)1
Authors: Hubbard Katherine A. , Rocap Gabrielle , Armbrust E. Virginia
Published: April 2008

Pseudo‐nitzschia‐specific PCR primers (PnAll F/R) were designed to amplify a polymorphic region of the internal transcribed spacer 1 (ITS1) from at least 11 Pseudo‐nitzschia species. The primers were used to generate environmental clone libraries from Puget Sound, Washington, and Vancouver Island, British Columbia, to confirm that the primers were specific for Pseudo‐nitzschia and to determine the extent of ITS1 sequence diversity within individual species. All environmental ITS1 sequences generated with PnAll primers displayed the greatest similarity to known Pseudo‐nitzschia ITS1 sequences. The length of cloned ITS1 fragments differed among species but was conserved within a species. Intraspecific genotypes exhibited <3% sequence divergence for seven of the 10 species detected in clone libraries. Several ITS1 genotypes unique to the Pacific Northwest were identified in environmental samples, and other genotypes were more broadly distributed. The Pseudo‐nitzschia primers were also used to develop an automated ribosomal intergenic spacer analysis (ARISA) to rapidly identify Pseudo‐nitzschia species in environmental samples based on species‐specific variation in the length of the targeted ITS1 region. The ARISA peaks were then associated with the environmental clone sequences for Pseudo‐nitzschia species. Surveying the genetic composition of communities at both the inter‐ and intraspecific levels will enhance our understanding of Pseudo‐nitzschia bloom dynamics.
Innate Differences in the Expression of Brain‐Derived Neurotrophic Factor in the Regions Within the Extended Amygdala Between Alcohol Preferring and Nonpreferring Rats
Authors: Prakash Anand , Zhang Huaibo , Pandey Subhash C.
Published: April 2008

Background:  Animal lines such as alcohol‐preferring (P) and nonpreferring (NP) rats appear to be suitable animal models to investigate the biological basis of alcohol‐drinking behaviors. The extended amygdala serves as a neuroanatomical substrate for alcohol‐drinking behaviors. Brain‐derived neurotrophic factor (BDNF) in the amygdala has been implicated in alcohol‐drinking behaviors; however, its expression in the extended amygdala of P and NP rats is unknown. Therefore, we examined the basal expression of BDNF in the extended amygdala of alcohol naïve P and NP rats.

Methods:  We determined the basal mRNA and protein levels of BDNF by in situ RT‐PCR and immuno‐histochemical procedure, respectively, in the amygdaloid [central nucleus of amygdala (CeA), medial nucleus of amygdala (MeA), and basolateral amygdala (BLA)], nucleus accumbal (NAc shell and core), and bed nucleus of stria terminalis (BNST) [lateral BNST (lBNST), medial BNST (mBNST), and ventral BNST (vBNST)] brain structures of P and NP rats. In addition, we examined the localization of BDNF in neurons using double‐immunofluorescence labeling of BDNF with neuron‐specific nuclear protein (NeuN) and also determined the number of NeuN‐positive neurons in the amygdaloid structures of P and NP rats.

Results:  The mRNA and protein levels of BDNF were found to be significantly lower in both the CeA and MeA, but not in the BLA, of P compared with NP rats. We also found that BDNF was expressed in neurons in the amygdaloid structures of P and NP rats. In addition, we found that the number of NeuN‐positive neurons was similar in the amygdaloid structures of P and NP rats. Interestingly, the mRNA and protein levels of BDNF were also significantly lower in the lBNST, mBNST, and vBNST of P compared with NP rats. On the other hand, mRNA and protein levels of BDNF were similar in the NAc shell and core structures of P and NP rats.

Conclusions:  P and NP rats are selectively bred for higher and lower alcohol preference, respectively; therefore it is possible that lower BDNF levels in the amygdaloid and BNST structures may be associated with the excessive alcohol‐drinking behaviors of P rats.
Smart Labels for Waste and Resource Management
Authors: Binder Claudia R. , Quirici Raffaele , Domnitcheva Svetlana , Stäubli Beat
Published: April 2008

This article explores the potential of RFID (radio frequency identification device) for improving the current waste and resource management system in Switzerland. It presents the following three possible options for utilizing RFID tags to support waste management processes: “at source automation” (using a “smart” trash can), “end of pipe I” (combination of the current system with an additional separation of recyclables before incineration), and “end of pipe II” (replacement of the current recycling infrastructure by sorting at the incineration plant). These options tackle the waste and resource management chain during different processes (i.e., waste generation, waste separation, and treatment). Based on an MFA (material flow analysis), we performed a multicriteria assessment of these options with experts from the waste management sector.

The assessment of ten experts in the waste management field regarding the proposed options for batteries and electrical appliances showed that, from an ecological perspective, the implementation of RFID in waste management would be desirable and would lead to an improvement in the current recycling rate in Switzerland for the goods studied. From an economic perspective, new investments would be required in the range of 1 to 5 times the maintenance costs of the current separate collection system. From a social perspective, the utilization of RFID tags in the waste management process was ambiguous. In particular, the end of pipe II option would, on the one hand, significantly improve convenience for consumers. On the other hand, experts see privacy and, what is more, social responsibility as being under threat. The experts considered the ecological and social aspects to be more relevant than the economic ones, preferring the end of pipe I option over the other options and the status quo.
Value of Real Time Three‐Dimensional Echocardiography in Patients with Hypertrophic Cardiomyopathy: Comparison with Two‐Dimensional Echocardiography and Magnetic Resonance Imaging
Authors: Bicudo Letícia S. , Tsutsui Jeane M. , Shiozaki Afonso , Rochitte Carlos E. , Arteaga Edmundo , Mady Charles , Ramires José A. F. , Mathias Jr Wilson
Published: April 2008

Real time three‐dimensional echocardiography (RT3DE) has been demonstrated to be an accurate technique to quantify left ventricular (LV) volumes and function in different patient populations. We sought to determine the value of RT3DE for evaluating patients with hypertrophic cardiomyopathy (HCM), in comparison with cardiac magnetic resonance imaging (MRI). Methods: We studied 20 consecutive patients with HCM who underwent two‐dimensional echocardiography (2DE), RT3DE, and MRI. Parameters analyzed by echocardiography and MRI included: wall thickness, LV volumes, ejection fraction (LVEF), mass, geometric index, and dyssynchrony index. Statistical analysis was performed by Lin agreement coefficient, Pearson linear correlation and Bland‐Altman model. Results: There was excellent agreement between 2DE and RT3DE (Rc = 0.92), 2DE and MRI (Rc = 0.85), and RT3DE and MRI (Rc = 0.90) for linear measurements. Agreement indexes for LV end‐diastolic and end‐systolic volumes were Rc = 0.91 and Rc = 0.91 between 2DE and RT3DE, Rc = 0.94 and Rc = 0.95 between RT3DE and MRI, and Rc = 0.89 and Rc = 0.88 between 2DE and MRI, respectively. Satisfactory agreement was observed between 2DE and RT3DE (Rc = 0.75), RT3DE and MRI (Rc = 0.83), and 2DE and MRI (Rc = 0.73) for determining LVEF, with a mild underestimation of LVEF by 2DE, and smaller variability between RT3DE and MRI. Regarding LV mass, excellent agreement was observed between RT3DE and MRI (Rc = 0.96), with bias of−6.3 g (limits of concordance = 42.22 to−54.73 g). Conclusion: In patients with HCM, RT3DE demonstrated superior performance than 2DE for the evaluation of myocardial hypertrophy, LV volumes, LVEF, and LV mass.
Differences in Echocardiographic Assessment with Standard Doppler and Tissue Doppler Imaging of Left Ventricular Filling Pressure in Idiopathic and Ischemic Dilated Cardiomyopathy
Authors: Costanzo Pierluigi , Prastaro Maria , Perrino Cinzia , Caiazzo Gianluca , Monda Cinzia , Guerra Giuseppina , Iorio Annamaria , Gargiulo Paola , Chiariello Massimo , Perrone‐Filardi Pasquale
Published: April 2008

Background: In idiopathic and ischemic dilated cardiomyopathy (DCM) there are differences in left atrial and ventricular relaxation. We assessed the hypothesis of an influence of these dissimilarities in assessing left ventricular filling pressure (LVFP) in these two DCMs by standard Doppler and tissue Doppler imaging. In particular, we focused on early transmitral flow to early diastolic motion velocity of mitral annulus ratio (E/Ea), useful to estimate normal or elevated LVFP. However, when found in intermediate range (8–15), its role is unclear. Methods and Results: We evaluated 26 patients with ischemic and 21 patients with idiopathic DCM. To validate the echocardiographic estimation of LVFP, a sample (12 patients) underwent LVFP assessment by catheterization. In idiopathic DCM, E/Ea directly related to duration of retrograde pulmonary venous flow (ARd) (r = 0.66 P = 0001). In ischemic DCM E/Ea inversely related only to systolic to diastolic velocity ratio of pulmonary venous flow (S/D) (r =−0.56 P = 0002). After a mean follow up of 6 months, by a second echocardiogram we observed a direct relation between E/Ea and ARd percentage variation (r = 0.52 P = 0.02) in idiopathic DCM group, whereas in the ischemic DCM group there was an inverse relation between E/Ea and S/D percentage variation (r =−0.59 P = 0.02).Conclusions: In conclusion, ARd in idiopathic and S/D in ischemic DCM might be used as specific additional information to estimate LVFP when E/Ea falls within intermediate range.
Is There Any Relationship between Metabolic Parameters and Left Ventricular Functions in Type 2 Diabetic Patients without Evident Heart Disease?
Authors: Yazici Mehmet , Ozdemir Kurtulus , Gonen Mustafa Sait , Kayrak Mehmet , Ulgen Mehmet Siddik , Duzenli Mehmet Akif , Yazici Raziye , Soylu Ahmet , Gok Hasan
Published: April 2008

Background: The aim of the present study was to evaluate left ventricle (LV) systolic and diastolic function, using tissue Doppler echocardiography (TDE) and color M‐mode flow propagation velocity, in relation to blood glucose status in normotensive patients with type 2 diabetes mellitus (T2DM) who had no clinical evidence of heart disease. Methods: Seventy‐two patients with T2DM (mean age 49.1 ± 9.8 years) without symptoms, signs or history of heart disease and hypertension, and 50 ages matched healthy controls (mean age 46.1 ± 9.8 years) had echocardiography. Systolic and diastolic LV functions were detected by using conventional echocardiography, TDE and mitral color M‐mode flow propagation velocity (VE). Fasting blood glucose level (FBG) after 8 hours since eating a meal, postprandial blood glucose level (PPG), and HbA1C level were determined. The association of FBG, PPG and HbA1C with the echocardiographic parameters was investigated. Results: It was detected that although systolic functions of two groups were similar, diastolic functions were significantly impaired in diabetics. No relation of FBG and PPG with systolic and diastolic functions was determined. However, HbA1C was found to be related to diastolic parameters such as E/A, Em/Am, VE and E/VE (β=−0.314, P = < 0.05; β=–0.230, P < 0.05; β=–0.602, P < 0.001, β= 0.387, P < 0.005, respectively). In addition to HbA1C, LV, diastolic functions were also correlated with age and diabetes duration. Conclusion: Diastolic LV dysfunction may develop even in absence of ischemia, hypertension, and LVH in T2DM. FBG and PPG have no effect on LV functions, but HbA1C levels may affect diastolic parameters.
Effect of fibroblast growth factor‐1 on the expression of early growth response‐1 in human periodontal ligament cells
Authors: Tamura I. , Chaqour B. , Howard P. S. , Ikeo T. , Macarak E. J.
Published: April 2008

Background and Objectives: Early growth response‐1 is a nuclear transcription factor implicated in regulating cell proliferation. Fibroblast growth factor‐1 is the prototypic fibroblast growth factor involved in the proliferation and differentiation of various cell types. Expression of early growth response‐1 induced by fibroblast growth factor‐1 thus may be very important for cell growth, during both development and wound healing in oral tissue. However, little is known about the expression and kinetics of early growth response‐1 in fibroblast growth factor‐1‐stimulated oral cells. The aim of this study was to investigate the effects of fibroblast growth factor‐1 on the expression of early growth response‐1 in human periodontal ligament cells.

Material and Methods: Periodontal ligament cells were cultured in medium containing 1, 10 or 100 ng/mL of fibroblast growth factor‐1 for 45 min or with 10 ng/mL of fibroblast growth factor‐1 for 15, 30, 45, 60 or 120 min. The proliferation of periodontal ligament cells was evaluated by measuring 5‐bromo‐2′‐deoxyuridine incorporation. The expression of early growth response‐1 mRNA and protein, and the localization of early growth response‐1 protein, were examined by western blotting, northern blotting and immunocytostaining.

Results: 5‐Bromo‐2′‐deoxyuridine incorporation correlated directly with increases in fibroblast growth factor‐1 concentration, and 5‐bromo‐2′‐deoxyuridine incorporation peaked 45 min after starting treatment. Early growth response‐1 protein was expressed in response to a concentration of fibroblast growth factor‐1 as low as 1 ng. Peak expression of early growth response‐1 mRNA was observed at 15 min and that of early growth response‐1 protein at 60 min. The 140‐kDa early growth response‐1 protein was not detected in the nuclear fraction, and the peak expression of the 80‐kDa early growth response‐1 protein occurred at 60 min. Early growth response‐1 localized in or around the nucleus at 30 min.

Conclusion: These results show that a concentration of fibroblast growth factor‐1 as low as 1 ng induces the expression of early growth response‐1 protein, and that the 80‐kDa early growth response‐1 protein functions in the nucleus of periodontal ligament cells treated with fibroblast growth factor‐1.
For Better or for Worse: Complexins Regulate SNARE Function and Vesicle Fusion
Authors: Brose Nils
Published: April 2008

In contrast to constitutive secretion, SNARE‐mediated synaptic vesicle fusion is controlled by multiple regulatory proteins, which determine the Ca2+sensitivity of the vesicle fusion process and the speed of excitation–secretion coupling. Complexins are among the best characterized SNARE regulators known to date. They operate by binding to trimeric SNARE complexes consisting of the vesicle protein synaptobrevin and the plasma membrane proteins syntaxin and SNAP‐25. The question as to whether complexins facilitate or inhibit SNARE‐mediated fusion processes is currently a matter of significant controversy. This is mainly because of the fact that biochemical experimentsin vitroand studies on vertebrate complexinsin vivohave yielded apparently contradictory results. In this review, I provide a summary of available data on the role of complexins in SNARE‐mediated vesicle fusion and attempt to define a model of complexin function that incorporates evidence for both facilitatory and inhibitory roles of complexins in SNARE‐mediated fusion.
Functional variation in the 3′ untranslated region of the serotonin transporter in human and rhesus macaque
Authors: Vallender E. J. , Priddy C. M. , Hakim S. , Yang H. , Chen G.‐L. , Miller G. M.
Published: April 2008

The serotonin system underlies a wide variety of behavioral traits and its dysregulation is the cause of numerous neuropsychiatric disorders. Among genes involved in the system, the serotonin transporter (SERT) is integral and has been repeatedly shown to be associated with disease as well as being a primary drug target. In addition to promoter region variation, we identify here variation in a regulatory region in the 3′ untranslated region (UTR) of the SERT gene in both humans and rhesus macaques. We comprehensively survey the 3′ UTR of SLC6A4 in Indian‐origin rhesus macaques to identify three single nucleotide polymorphisms (SNPs) creating two haplotypes, both derived from an ancestral sequence, that represent the vast majority of the alleles in the population. Through the use of a luciferase reporter gene assay, we are able to show that not only do these alleles have differential effects on gene expression, modulated through changes in messenger
RNA stability, but that different commonly occurring SNPs in the human 3′ UTR also have similar effects. This finding not only offers additional insight into the regulation, and thus dysregulation, of SERT expression, but also suggests the role of natural selection in maintaining both high and low SERT expression levels broadly across populations of multiple primate species.
Intermittent hypoxia is a key regulator of cancer cell and endothelial cell interplay in tumours
Authors: Toffoli S. , Michiels C.
Published: April 2008

Solid tumours are complex structures in which the interdependent relationship between tumour and endothelial cells modulates tumour development and metastasis dissemination. The tumour microenvironment plays an important role in this cell interplay, and changes in its features have a major impact on tumour growth as well as on anticancer therapy responsiveness. Different studies have shown irregular blood flow in tumours, which is responsible for hypoxia and reoxygenation phases, also called intermittent hypoxia. Intermittent hypoxia induces transient changes, the impact of which has been underestimated for a long time. Recent in vitro and in vivo studies have shown that intermittent hypoxia could positively modulate tumour development, inducing tumour growth, angiogenic processes, chemoresistance, and radioresistance. In this article, we review the effects of intermittent hypoxia on tumour and endothelial cells as well as its impacts on tumour development.
Using Rheology to Achieve Co‐Extrusion of Cement‐Based Materials with Graded Cellular Structures
Authors: Chen Yunbo , Struble Leslie J. , Paulino Glaucio H.
Published: April 2008

Co‐extrusion involves simultaneous extrusion of multiple layers and can be used to produce functionally graded materials whose layers have different properties. Rheological control is vital for successful co‐extrusion. During extrusion, flow in the barrel and die land in a ram extruder should be plug‐like, while the paste should be sheared and uniformly elongated in the die entry region. In the barrel of the extruder, the paste flow velocity field was inferred by direct observation of the paste left in the barrel, and evidence for plug flow in the barrel was seen only at low‐extrudate velocities. In the die land, the Benbow nonlinear model was employed to assess the paste flow behavior, and plug flow was achieved only when the shear stress applied to the paste by the die land wall was smaller than its yield stress. For co‐extrusion, a simple method using thin‐walled tubes was found to be effective to prepare layered feedrods. Functionally graded cellular structures of cement‐based materials were successfully co‐extruded by using a low‐extrudate velocity when the paste had decreasing shear viscosity from inner to outer layers.
Erosion–Corrosion‐Resistant Titanium Diboride Cermets for High‐Temperature Process Applications
Authors: Chun Chang Min , Bangaru Narasimha‐Rao V. , Thirumalai Neeraj , Peterson John R. , Fowler Christopher J. , Antram Robert L.
Published: April 2008

Reactor vessels and internals used for high‐temperature processes such as in refining and chemical industries are exposed to aggressive fluids often containing hard catalyst particles moving at high velocities. The protection of these vessels and internals against erosion‐ and corrosion‐induced material degradation is a technological challenge. The life span of the state–of‐the‐art monolithic refractory liners currently in use is limited by excessive mechanical attrition of the liner from high‐velocity solid particle impingement, mechanical cracking, and spalling. The advanced TiB2‐stainless‐steel (SS) cermets are designed for chemical stability required for long‐term service and offer an order of magnitude higher erosion resistance over the state‐of‐the‐art, high fracture toughness (K1C∼12 MPa m1/2) and excellent corrosion resistance (kp∼1.9 × 10−11 g2/cm4/s at 800°C in air). Materials, design, microstructure, key mechanical properties, erosion, and corrosion resistance of the newly developed TiB2‐SS cermets are presented.
Low‐Temperature Firing and Microwave Dielectric Properties of Ca[(Li1/3Nb2/3)0.8Ti0.2]O3−δ Ceramics with ZnB2O4 Glass Addition
Authors: Pang Li‐Xia , Wang Hong , Zhou Di , Zhou Huan‐Fu , Yao Xi
Published: April 2008

Low‐temperature sintered Ca[(Li1/3Nb2/3)0.8Ti0.2]O3−δ microwave dielectric ceramics with ZnB2O4 glass (ZBG) addition were prepared by the conventional solid state reaction method. The sintering behavior, microstructure, and microwave dielectric properties of Ca[(Li1/3Nb2/3)0.8Ti0.2]O3−δ ceramics with ZBG addition were investigated. The ZBG addition lowered the densified temperature of Ca[(Li1/3Nb2/3)0.8Ti0.2]O3−δ ceramics from 1150°C to 940°C. The dielectric constants of Ca[(Li1/3Nb2/3)0.8Ti0.2]O3−δ ceramics decreased from 40 to 34 and the temperature coefficient of resonant frequency (τf) changed gradually from +12.7 to −25.7 ppm/°C as ZBG addition increased from 0 to 8 wt%. The Qf values increased greatly from 20,500 GHz of pure Ca[(Li1/3Nb2/3)0.8Ti0.2]O3−δ to 26,900 GHz when 5 wt% ZBG was added. Ca[(Li1/3Nb2/3)0.8Ti0.2]O3−δ ceramics with 8 wt% ZBG addition sintered at 940°C show good microwave dielectric properties with ɛr∼32.5, Qf∼20,600 GHz, and τf∼−25.7 ppm/°C. The relationship between dielectric properties and microstructure was also discussed.
Preparation of a Nanoscale/SOFC‐Grade Yttria‐Stabilized Zirconia Material: A Quasi‐Optimization of the Hydrothermal Coprecipitation Process
Authors: Chang Yang‐Chuang , Lee Maw‐Chwain , Kao Wei‐Xin , Lin Tai‐Nan
Published: April 2008

Yttria‐stabilized zirconia (YSZ) is the key material for an electrolyte of a solid oxide fuel cell (SOFC). In order to prepare a nanoscale/SOFC‐grade 8YSZ material, the hydrothermal coprecipitation process is intensively investigated for process improvement and product identification. From the characterization results of the 8YSZ product, the operation conditions were selected for process optimization. The criteria used in optimization condition determination were the reproducibility of the 8YSZ product and the particle size, the crystallinity, as well as the operation simplicity. Experimental results showed that a nanoscale/SOFC‐grade 8YSZ powder was directly prepared. The quasi‐optimum conditions of the process are proposed.
Influence of Wet Mechanical Mixing on Microstructure and Vickers Hardness of Nanocrystalline Ceramic–Metal Composites
Authors: Kumagai Tatsuo , Hongo Kazuhiro
Published: April 2008

Nanocrystalline (nc) ceramic–metal composite bulk samples have been fabricated by consolidation of mixture of attrition‐milled (AM) amorphous base ceramic ((ZrO2–3 mol% Y2O3)–20 mol% Al2O3) and AM amorphous base metallic (Ti–48 mol% Al) powders using a pulse‐current pressure sintering system. Microstructural observations revealed that the ceramic and metallic colonies appear blocky in morphology in the composite bulk samples, and both the ceramic and the metallic colonies consist of a large number of equiaxed fine grains with the sizes of 78–82 and 81–86 nm, respectively. Mechanical mixing treatments by wet ball milling in ethanol before consolidation process are effective for refinement of the ceramic and metallic colonies. In all the obtained composite bulk samples, the ceramic colonies consist of the dominant phase of tetragonal (t) ZrO2 solid solution (ss) together with the minor phases of monoclinic (m) ZrO2ss and α‐Al2O3. On the other hand, the dominant phase in the metallic colonies changes from Ti3Al (α2) to Tiss (α) with an increase in the t‐ZrO2ss volume fraction by abrasion of 3 mol% yttria‐stabilized tetragonal polycrystalline zirconia balls during wet mechanical mixing treatments. Such a phase transformation from α2 to α is considered to be due to the decrease in the aluminum content in the metallic colonies by combination of aluminum with oxygen (i.e., the formation of α‐Al2O3), which is probably taken from ethanol (C2H5OH) into the powders during wet mechanical mixing treatments. The obtained nc composite bulk samples show good Vickers hardness values, which are considerably higher than those estimated from the rule of mixture.
Nanosecond‐Laser Postprocessing of Millisecond‐ Laser‐Machined Zirconia (Y‐TZP) Surfaces
Authors: Parry Jonathan P. , Shephard Jonathan D. , Dear Fraser C. , Jones Nick , Weston Nick , Hand Duncan P.
Published: April 2008

Millisecond‐pulsed Nd:YAG laser systems can be used for high‐speed cutting of ceramics, due to the high average power available. However, due to the relatively long pulse duration (0.3–5 ms), millisecond laser‐machining is predominantly a thermal, melt‐eject process. The quality of the finished surface is limited by a redeposited melt and a heat‐affected zone, in particular surface cracking. Shorter pulse duration lasers can provide a better surface finish but with a significantly longer processing time. This paper presents a method of improving the finish of millisecond‐machined yttria‐stabilized tetragonal zirconia polycrystal surfaces by postprocessing with a nanosecond‐pulsed laser. Nanosecond machining was carried out directly onto the as‐cut surface produced after millisecond processing, yielding a dramatic improvement of the surface finish in a relatively short time.
Fracture Toughness Enhancement for Alumina Systems: A Review
Authors: Ighodaro Osayande L. , Okoli Okenwa I.
Published: April 2008

Investigations have been carried out to determine ways of tailoring ceramic materials in order that one or more toughening mechanisms are activated in service. Microstructural manipulations, as well as composite formulations involving metallic, intermetallics, and ceramic phases have been used with ceramic matrices. Macrostructurally, laminated structures and functional gradient materials (FGMs) have also been formulated to enhance mechanical properties. Although significant improvements in material properties have been reported, ceramics are still below their projected positions on the materials map. This article presents a review of research activities pursuant to improving fracture toughness of alumina matrix systems and the enhancements achieved.
Low‐Pressure Injection Molding of Ceramic Springs
Authors: Krindges Israel , Andreola Raquel , Perottoni Cláudio A. , Zorzi Janete E.
Published: April 2008

Injection molding has important advantages over other methods for the production of advanced ceramic parts with complex shapes. In this work, low‐pressure injection molding was used to produce helical ceramic springs using two different kinds of molds. The ceramic powders used were submicrometer‐sized alumina and partially stabilized zirconia. Sintered alumina and zirconia springs were obtained free of defects, with densities from 96% to 99% of the theoretical value. In preliminary mechanical tests, these ceramic springs supported axial deformations up to 10% before failure.
Polyphagy and Obligate Myrmecophily in the Butterfly Hallonympha paucipuncta (Lepidoptera: Riodinidae) in the Neotropical Cerrado Savanna
Authors: Kaminski Lucas A.
Published: April 2008

This study analyzes host plant use and obligate myrmecophily in Hallonympha paucipuncta, an endemic butterfly of the Cerrado. Larvae of H. paucipuncta are polyphagous, using at least 19 species of plants in 10 families. All larvae found were being tended by Crematogaster ants. Spatial distribution of larvae and tending ants were strongly aggregated, suggesting an influence of ants on oviposition and/or larval survival. Implications of obligate myrmecophily in the evolution of polyphagy in Riodinidae are discussed.
Functional Significance of Interspecific Variation inBurmeisteraFlower Morphology: Evidence from Nectar Bat Captures in Ecuador
Authors: Muchhala Nathan
Published: April 2008

What causes flowers to diverge? While a plant's primary pollinator should strongly influence floral phenotype, selective pressures may also be exerted by other flower visitors or competition with other plants for pollination. Species of the primarily bat‐pollinated genusBurmeistera(Campanulaceae) frequently cooccur, with up to four species in a given site, and broadly overlap in flowering phenology, typically flowering throughout the year. The genus displays extensive interspecific variation in floral morphology in the degree that the reproductive parts (anthers and stigma) are exserted outside of the corolla, and species can be roughly classified as either long or short‐exserted. I tested two hypotheses regarding the functional significance of such variation: (1) exsertion lengths correspond to pollination by bat species of different sizes; and (2) variation serves to partition pollinator's bodies spatially and thus reduces interspecific pollen transfer. I captured bats in Ecuador to evaluate the identity and location of theBurmeisterapollen they were carrying. Results show that exsertion does not correspond to specialization on different pollinators; different bat species carried pollen of both flower types just as frequently. In support of the second hypothesis, pollen from flowers of different exsertion lengths was found to occur on different regions of bats' heads. This may serve to reduce competition for pollination among coexistingBurmeistera.
Reduced Photoperiod Induces Partially Synchronous Flowering in an Understory Rain Forest Herb, Begonia urophylla in Costa Rica
Authors: Rivera Jeanette , Cozza John
Published: April 2008

The monoecious understory herb Begonia urophylla blooms in the dry season at Las Cruces, Costa Rica, and bloom is partially synchronized. A laboratory experiment investigated reduced photoperiod as an unambiguous cue for flowering. The inductive period was 3 weeks for flowers but less for bud formation. Variation in bloom time may be an adaptation to enhance fitness gain of plants, such as B. urophylla, with sequential male and female phases.
Genetic Structure in Remnant Populations of an Endangered AndeanMagnolia
Authors: López‐A Diana M. , Bock Brian C. , Bedoya Gabriel
Published: April 2008

By genetically characterizing adult individuals, we documented the presumed prefragmentation population structure of an endangered Andean tree,Magnolia espinalii. Our sample included all known surviving individuals for this species. Genetic diversity was high, but genetic distance was not related to geographic distance between sites.Magnolia espinaliiapparently was originally distributed in numerous semi‐isolated demes. The lack of evidence of recruitment around most adults in this species suggests a fragmentation‐related disruption of their reproductive ecology. Artificial propagation projects should obviously attempt to involve all 23 known surviving trees.
A Model Stomach System to Investigate Disintegration Kinetics of Solid Foods during Gastric Digestion
Authors: Kong F. , Singh R.P.
Published: April 2008

ABSTRACT:  Knowledge of the disintegration kinetics of food particulates in the human stomach is essential for assessing the bioaccessibility of nutrients in solid foods and understanding stomach emptying. The objective of this study was to develop a model stomach system and to investigate the kinetics of food disintegration. Our system consisted mainly of a turntable and a jacketed glass chamber containing simulated gastric juice in which plastic beads were added to simulate food particulates as well as provide a suitable mechanical destructive force on food samples. The mechanical force on the samples was simultaneously measured using the load cell of a TA‐XT2 texture analyzer. Cylindrical carrots and ham samples were used as representative foods. The system is capable of simulating the in vivo stomach in terms of providing a wide range of continuous and periodic forces comparable to those measured in vivo. The modified power exponential function of the form yt= 1 – (1 –e−kt)β, where yt is the mass retention ratio at time t, provided a reasonable description for the disintegration performance of tested foods. The mass retention curve can be either a sigmoidal decay with an initial delay or an exponential decay, which are decided largely by the hardness of the foods during digestion and the extent of physical force acting on the foods. A good match was observed between the kinetics of food disintegration and in vivo stomach emptying.
Stationary‐Increment Variance‐Gamma and t Models: Simulation and Parameter Estimation
Authors: Finlay Richard , Seneta Eugene
Published: April 2008

We detail a method of simulating data from long range dependent processes with variance‐gamma or t distributed increments, test various estimation procedures [method of moments (MOM), product‐density maximum likelihood (PMLE), non‐standard minimumχ2and empirical characteristic function estimation] on the data, and assess the performance of each. The investigation is motivated by the apparent poor performance of the MOM technique using real data (Tjetjep & Seneta, 2006); and the need to assess the performance of PMLE for our dependent data models. In the simulations considered the product‐density method performs favourably.
Tests of Bivariate Exchangeability
Authors: Modarres Reza
Published: April 2008

We discuss the hypothesis of bivariate exchangeability and show that testing bivariate exchangeability is related to the two‐sample testing of equality of distribution functions. We consider three test statistics based on the ordering of the Euclidean interpoint distances. The runs test of exchangeability counts the runs among the observations and their mirror images on the minimal spanning tree. The nearest neighbour test of exchangeability is based on the number of nearest neighbour type coincidences among the observations and their folded images on the plane. The rank test of exchangeability compares the within and between ranks of the interpoint distances. We also consider the sign test of exchangeability, which uses the signs of the observations in specific regions, and a bootstrap test of exchangeability based on the maximum distance between the mirror images. We compare the power of these methods in a Monte Carlo study which shows different power orderings of the methods, depending on the alternative hypothesis.