bluuebunny/crossref_metadata_2025 huggingface dataset:
Spectroscopic investigations of the chiral interactions between lipase and the herbicide dichlorprop
Authors: Wen Yue‐Zhong , Yuan Yu‐Li , Shen Chen‐Si , Liu HUI‐Jun , Liu Wei‐Ping
Published: June 2008

The enantioselective interaction between penicillium expansum alkaline lipase and chiral phenoxypropionic acid herbicide dichlorprop was studied by using UV differential spectrophotometry and fluorescence spectrophotometry in the presence of a pH 8, phosphate buffer solution. Chiral differences in the UV absorption and fluorescence spectra of lipase with dichlorprop were detected. (R)‐Dichlorprop interacted the strongest with lipase as measured by both UV absorption and fluorescence spectrophotometry, followed by (Rac)‐dichlorprop, while (S)‐dichlorprop had the weakest interaction. The hydrophobic interaction seem to play the dominant role in the interactions and the (R)‐enantiomer needed the minimum put of energy to drive the endothermic reaction, while the Rac‐type and S‐type compounds needed more for the reaction to take place. In the meantime, the catalytic hydrolysis of FDA with lipase show that (R)‐DCPP could inhibit lipase the most strongly relatively at the same condition, perhaps because (R)‐DCPP had a stronger combining effect and high enantiomeric selectivity on lipase than (Rac)‐DCPP and (S)‐DCPP. Chirality, 2009. © 2008 Wiley‐Liss, Inc.
Fast retinal vessel tree extraction: A pixel parallel approach
Authors: Alonso‐Montes C. , Vilariño D. L. , Dudek P. , Penedo M. G.
Published: June 2008

Early ocular disease diagnosis is an important field in medical research. From the image processing point of view, many strategies and algorithms have been developed to deal with the extraction of the retinal vessel tree. Although reliable and accurate results have been obtained, the main disadvantage in most of these proposals is the high computation effort required. In this paper, a methodology to extract the retinal vessel tree has been developed and tested in a fine‐grain pixel‐parallel processor array. An analysis of the execution time has been made to demonstrate its capabilities regarding the computation speed. Moreover, an analysis of the accuracy using a publicly available database has been made to validate the algorithm performance. Copyright © 2008 John Wiley & Sons, Ltd.
VAMP2 is expressed in myogenic cells during rat development
Authors: Tajika Yuki , Murakami Tohru , Sato Mahito , Kubota Fumitaka , Yorifuji Hiroshi
Published: June 2008

Vesicle‐associated membrane protein 2 (VAMP2) is a member of the SNARE family of proteins that regulate the intracellular vesicle fusion process. This study investigated the developmental expression of VAMP2 in the rat embryo. In the trunk, VAMP2 was primarily found in the heart on embryonic day (E) 10. On E12.5, VAMP2 expression was found in nerve fibers, somites, and heart. In somites, epithelial cells in the dorsomedial lip, and elongated myoblasts in myotome were positive for VAMP2. On E16.5, VAMP2 was expressed in the heart, nerve fibers, and skeletal muscles. In skeletal muscles, multinuclear myotubes were positive for VAMP2. In the head, where muscles are derived both from somitic and non‐somitic origin, VAMP2 was found in myotubes of the extrinsic ocular muscles and masseter muscle on E16.5. These findings suggest the involvement of VAMP2 in the development of skeletal muscles of somitic and non‐somitic origins. Developmental Dynamics 237:1886–1892, 2008. © 2008 Wiley‐Liss, Inc.
Two different mechanisms of planar cell intercalation leading to tissue elongation
Authors: Honda Hisao , Nagai Tatsuzo , Tanemura Masaharu
Published: June 2008

During development, certain cells intercalate with each other towards tissue‐elongation, exemplified in sea‐urchin gut‐elongation, amphibian gastrulation, and Drosophila germ‐band extension. Their mechanism is not universal among intercalation events. To clarify the minimal cellular properties required for cell‐intercalation, we computer‐simulated the process using three‐dimensional geometrical cell‐models. We identified two different mechanisms: (1) cell‐junction‐remodeling by cell‐junction contraction along a specific direction, as observed in Drosophila germ‐band extension, and (2) cell‐shuffling by orientated cell‐extension of bipolar cells, as observed in amphibian gastrulation. The cell‐junction‐remodeling was characterized by well‐defined accumulation of contractile molecules along a specific direction of cell‐junctions. Length contraction of approximately one cell‐junction per cell is enough for the entire tissue‐elongation. The cell‐shuffling was characterised by rhythmic cell‐extension and orientated movement of cytoskeleton within the elongated cells. Furthermore, tissue‐elongation along a polarized axis was limited to a 2.5‐fold increase in the cell‐junction‐remodeling, while no limit was defined for the cell‐shuffling. Developmental Dynamics 237:1826–1836, 2008. © 2008 Wiley‐Liss, Inc.
Loss of the Prader‐Willi syndrome protein necdin causes defective migration, axonal outgrowth, and survival of embryonic sympathetic neurons
Authors: Tennese Alysa A. , Gee Christopher B. , Wevrick Rachel
Published: June 2008

Prader‐Willi syndrome is a neurodevelopmental disorder marked by abnormalities in feeding, drinking, thermoregulation, intestinal motility, and reproduction, suggesting disruption of the autonomic nervous system. Necdin, one of several proteins genetically inactivated in individuals with Prader‐Willi syndrome, is important for the differentiation of central and sensory neurons. We now show that formation, migration, and survival of sympathetic superior cervical ganglion neurons are impaired in Ndn‐null embryos. We observed reduced innervation of superior cervical ganglion target organs, including the submandibular gland, parotid gland, and nasal mucosa. While the formation of other sympathetic chain ganglia is unaffected, axonal extension is impaired throughout the sympathetic nervous system. These results demonstrate a novel role for necdin in cellular migration, in addition to its roles in survival and axon outgrowth. Furthermore, reduced sympathetic function provides a plausible explanation for deficiencies of salivary gland function in individuals with congenital necdin deficiency consequent to Prader‐Willi syndrome. Developmental Dynamics 237:1935–1943, 2008. © 2008 Wiley‐Liss, Inc.
Developmental pathways of eating problems in adolescents
Authors: Aimé Annie , Craig Wendy M. , Pepler Debra , Jiang Depeng , Connolly Jennifer
Published: June 2008

Objective:

To examine the developmental eating trajectories of adolescents and identify psychological correlates and risk factors associated with those trajectories.

Method:

Seven hundred thirty‐nine adolescents completed self‐reported measures of eating problems, internalizing and externalizing behaviors, alcohol and drug use, peer victimization, and depression.

Results:

Five eating trajectories were obtained. The proportions of males and females were the same in the increasing eating problems trajectory. For both genders, internalizing and externalizing problems were identified as associated risk factors of an eating pathology and reporting at least some eating problems was associated with an increased likelihood of psychological problems. Other risk factors found only in boys were frequency of drug use, victimization, and depressive symptoms.

Conclusion:

Externalizing problems in girls and internalizing behaviors in boys with disordered eating should not be overlooked. Atypical eating behaviors in boys are of particular concern since it increases their risk of cooccurring psychopathology. © 2008 by Wiley Periodicals, Inc. Int J Eat Disord 2008
Revisiting differences in individuals with bulimia nervosa with and without a history of anorexia nervosa: Eating pathology, personality, and maltreatment
Authors: Bardone‐Cone Anna M. , Maldonado Christine R. , Crosby Ross D. , Mitchell James E. , Wonderlich Stephen A. , Joiner Thomas E. , Crow Scott J. , Peterson Carol B. , Klein Marjorie H. , le Grange Daniel
Published: June 2008

Objective:

Early research in subtyping bulimia nervosa (BN) by history of anorexia nervosa (AN) generally found more similarities than differences, but recent research and limitations of the early work suggest the need to revisit this approach. We examine differences between women with BN with and without a history of AN regarding eating pathology, personality, and childhood maltreatment.

Method:

Participants were women (aged 18–55) recruited from the community and eating disorder clinics who metDSM‐IVcriteria for BN; 37 had a history of AN and 101 did not. Participants completed questionnaires related to eating disorder pathology, multidimensional perfectionism, multidimensional impulsivity, and childhood maltreatment.

Results:

Women with BN and a history of AN had higher levels of dietary restraint and purging and lower body mass indices as well as higher levels of all forms of childhood neglect and abuse. In contrast, no group differences were found for perfectionism or impulsivity dimensions.

Conclusion:

The group differences in terms of eating pathology and maltreatment have clinical implications. Further research is needed regarding if and how a history of AN among those with BN may reflect different etiological pathways and predict different outcomes. © 2008 by Wiley Periodicals, Inc. Int J Eat Disord 2008
Numbers of scaled and matched accelerograms required for inelastic dynamic analyses
Authors: Hancock Jonathan , Bommer Julian J. , Stafford Peter J.
Published: June 2008

Selecting, scaling and matching accelerograms are critically important to engineering design and assessment, enabling structural response to be determined with greater confidence and through fewer analyses than if unscaled accelerograms are employed. This paper considers the response of an 8‐storey multiple‐degree‐of‐freedom reinforced concrete structure to accelerograms selected, linearly scaled or spectrally matched using five different techniques. The first method consists of selecting real records on the basis of seismological characteristics, while the remaining methods make an initial selection on the basis of magnitude and spectral shape before (1) scaling to the target spectral acceleration at the initial period; (2) scaling to the target spectrum over a range of periods; (3) using wavelet adjustments to match the target spectrum and (4) using wavelet adjustments to match multiple target spectra for multiple damping ratios. The analyses indicate that the number of records required to obtain a stable estimate of the response decreases drastically as one moves through these methods. The exact number varies among damage measures and is related to the predictability of the damage measure. For measures such as peak roof and inter‐storey drift, member end rotation and the Park and Ang damage index, as few as one or two records are required to estimate the response to within ±5% (for a 64% confidence level) if matching to multiple damping ratios is conducted. Bias checks are made using predictive equations of the expected response derived from the results of 1656 nonlinear time‐domain analyses of the structure under the action of unscaled accelerograms. Copyright © 2008 John Wiley & Sons, Ltd.
Combustion of a substitution fuel made of cardboard and polyethylene: influence of the mix characteristics—modeling
Authors: Salvador S. , Quintard M. , David C.
Published: June 2008

The model proposed in this paper describes the combustion of a porous medium subjected to a radiative heat flux at its surface. There is no forced convection of air through the medium; hence this situation corresponds to the one encountered at the surface of fuel elements such as pellets, bricks or ballots, inside a furnace or kiln. Ash is not removed from the surface. No assumption is madea prioriin terms of the limiting phenomena. The medium is composed of cardboard and polyethylene (PE). Based on previous experimental work (Fuel2004;83:451–462), the material is assumed to be a macroscopically homogeneous porous medium. Local thermal equilibrium is also assumed. Most of the parameters required for the modeling were determined from specific experiments. Good predictions of the sample mass evolution and of the temperature levels inside the sample body were obtained for a large range of densities and PE content. A devolatilization front of about 20 mm first propagates inside the medium. The volatile matter flux is advected to the surface, which leads to the formation of the flame above the surface. Then a second char oxidation front propagates, starting from the surface. The front thickness is approximately 25 mm under the experimental conditions. Copyright © 2008 John Wiley & Sons, Ltd.
Effects of anterior cingulate fissurization on cognitive control during stroop interference
Authors: Huster Rene J. , Wolters Carsten , Wollbrink Andreas , Schweiger Elisabeth , Wittling Werner , Pantev Christo , Junghofer Markus
Published: June 2008

The midcingulate cortex, as part of the more anteriorly located cingulate regions, is thought to play a major role in cognitive processes like conflict monitoring or response selection. Regarding midcingulate fissurization, the occurrence of a second or paracingulate sulcus is more common in the left than in the right hemisphere and has been shown to be associated with an advantageous performance on tests of executive functions. However, the cognitive mechanisms underlying such behavioral differences are completely unknown. The current study addressed this issue by comparing subjects with a low and a high degree of left hemispheric midcingulate fissurization while collecting behavioral as well as electrophysiological correlates of Stroop interference. A high degree of fissurization was associated with decreased behavioral Stroop interference accompanied by a stronger and prolonged frontal negative potential to incongruent trials starting around 320 ms. This increased frontal negativity is assumed to reflect an enhanced activity of a conflict monitoring system located in the midcingulate cortex. In contrast and starting around 400 ms, subjects with low fissurization revealed an increased positivity over parieto‐occipital regions suggesting a compensatory need for enhanced effortful cognitive control in this group. These results contribute to the understanding of the neuronal implementation of individual differences regarding attentional mechanisms. Hum Brain Mapp 2009. © 2008 Wiley‐Liss, Inc.
Effect of handedness on fMRI activation in the medial temporal lobe during an auditory verbal memory task
Authors: Cuzzocreo Jennifer L. , Yassa Michael A. , Verduzco Guillermo , Honeycutt Nancy A. , Scott David J. , Bassett Susan Spear
Published: June 2008

Several studies have shown marked differences in the neural localization of language functions in the brains of left‐handed individuals when compared with right‐handers. Previous experiments involving functional lateralization have demonstrated cerebral blood flow patterns that differ concordantly with subject handedness while performing language‐related tasks. The effect of handedness on function in specific stages of memory processing, however, is a largely unexplored area. We used a paired‐associates verbal memory task to elicit activation of neural areas related to declarative memory, examining the hypothesis that there are differences in activation in the medial temporal lobe (MTL) between handedness groups. 15 left‐handed and 25 right‐handed healthy adults were matched for all major demographic and neuropsychological variables. Functional and structural imaging data were acquired and analyzed for group differences within MTL subregions. Our results show that activation of the MTL during declarative memory processing varies with handedness. While both groups showed activation in left and right MTL subregions, the left‐handed group showed a statistically significant increase in the left hippocampus and amygdala during both encoding and recall. No increases in activation were found in the right‐handed group. This effect was found in the absence of any differences in performance on the verbal memory task, structural volumetric disparities, or functional asymmetries. This provides evidence of functional differences between left‐handers and right‐handers, which extends to declarative memory processes. Hum Brain Mapp 2009. © 2008 Wiley‐Liss, Inc.
Source estimates for MEG/EEG visual evoked responses constrained by multiple, retinotopically‐mapped stimulus locations
Authors: Hagler Donald J. , Halgren Eric , Martinez Antigona , Huang Mingxiong , Hillyard Steven A. , Dale Anders M.
Published: June 2008

Studying the human visual system with high temporal resolution is a significant challenge due to the limitations of the available, noninvasive measurement tools. MEG and EEG provide the millisecond temporal resolution necessary for answering questions about intracortical communication involved in visual processing, but source estimation is ill‐posed and unreliable when multiple; simultaneously active areas are located close together. To address this problem, we have developed a retinotopy‐constrained source estimation method to calculate the time courses of activation in multiple visual areas. Source estimation was disambiguated by: (1) fixing MEG/EEG generator locations and orientations based on fMRI retinotopy and surface tessellations constructed from high‐resolution MRI images; and (2) solving for many visual field locations simultaneously in MEG/EEG responses, assuming source current amplitudes to be constant or varying smoothly across the visual field. Because of these constraints on the solutions, estimated source waveforms become less sensitive to sensor noise or random errors in the specification of the retinotopic dipole models. We demonstrate the feasibility of this method and discuss future applications such as studying the timing of attentional modulation in individual visual areas. Hum Brain Mapp, 2009. © 2008 Wiley‐Liss, Inc.
Enhancing action by sulfated hyaluronan on connexin‐26, ‐32, and ‐43 gene expressions during the culture of normal human astrocytes
Authors: Ahmed Saifuddin , Tsuchiya Toshie , Nagahata‐Ishiguro Misao , Sawada Rumi , Banu Nasreen , Nagira Tsutomu
Published: June 2008

Astrocyte proliferation is strictly controlled during development and in the adult nervous system. In this study, we examined the role of sulfated hyaluronan (SHya) in the proliferation and differentiation of normal human astrocytes (NHAs). Cells were cultured with different concentrations of SHya for 7 days, and the number of viable cells and the presence of neural cell‐specific genes were determined to assess their proliferation and development, respectively. With SHya, cell proliferation increased nonsignificantly. Furthermore, remarkable enhancing action by SHya on connexin‐26, ‐32, and ‐43 gene expressions were observed during the culture of NHAs. It has been suggested that a fraction of NHAs have neural precursor activity that gives rise to astrocytes themselves, oligodendrocytes, and neurons. Our results clearly demonstrated that the expression of specific genes for neural precursor cells, astrocytes, neurons, and oligodendrocytes was significantly increased to 50 μg/mL in SHya‐treated cultures when compared with that of the control culture. These findings suggest that SHya plays an important role in the proliferation and differentiation of NHAs and in the production of a novel material for tissue engineering. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Effects of PEG hydrogel crosslinking density on protein diffusion and encapsulated islet survival and function
Authors: Weber Laney M. , Lopez Christina G. , Anseth Kristi S.
Published: June 2008

The rational design of immunoprotective hydrogel barriers for transplanting insulin‐producing cells requires an understanding of protein diffusion within the hydrogel network and how alterations to the network structure affect protein diffusion. Hydrogels of varying crosslinking density were formed via the chain polymerization of dimethacrylated PEG macromers of varying molecular weight, and the diffusion of six model proteins with molecular weights ranging from 5700 to 67,000 g/mol was observed in these hydrogel networks. Protein release profiles were used to estimate diffusion coefficients for each protein/gel system that exhibited Fickian diffusion. Diffusion coefficients were on the order of 10−6–10−7 cm2/s, such that protein diffusion time scales (td = L2/D) from 0.5‐mm thick gels vary from 5 min to 24 h. Adult murine islets were encapsulated in PEG hydrogels of varying crosslinking density, and islet survival and insulin release was maintained after two weeks of culture in each gel condition. While the total insulin released during a 1 h glucose stimulation period was the same from islets in each sample, increasing hydrogel crosslinking density contributed to delays in insulin release from hydrogel samples within the 1 h stimulation period. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Ethyl‐cyanoacrylate is acutely nontoxic and provides sufficient bond strength for anastomosis of peripheral nerves
Authors: Rickett Todd , Li Jianming , Patel Meenal , Sun Wenjing , Leung Gary , Shi Riyi
Published: June 2008

Anastomosis is a common technique for the union of severed nerve trunks. This is commonly performed with sutures, a process that can be both time consuming and injurious to tissue. One promising alternative to suturing is the use of adhesives to join the severed segments. Cyanoacrylate‐based glues have been used clinically as a surgical adhesive for soft tissues. However, the acute effects of these glues on nerve electrophysiology and the tensile strength of the rejoined tissues have not been evaluated. Using a guinea pig model, we analyzed the mechanical properties of transected sciatic nerves repaired with epineural application of ethyl‐cyanoacrylate and the short term consequences of cyanoacrylate application on impulse conduction. Results showed that nerves coapted with ethyl‐cyanoacrylate were capable of bearing in vivo forces. Additionally, no acute effects on conduction were observed in uninjured sciatic nerves exposed to ethyl‐cyanoacrylate. In conjunction with long term in vivo reports from literature, the current results support the use of cyanoacrylates in nerve repair. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Composite implantation of mesenchymal stem cells with endothelial progenitor cells enhances tissue‐engineered bone formation
Authors: Usami Kazutada , Mizuno Hirokazu , Okada Kunihiko , Narita Yuji , Aoki Mika , Kondo Takahisa , Mizuno Daiki , Mase Junji , Nishiguchi Hiroaki , Kagami Hideaki , Ueda Minoru
Published: June 2008

For successful tissue engineering, neovascularization of the implanted tissue is critical. Factors generated by endothelial cells are also considered crucial for the process of osteogenesis. The direct effects of supplementing tissue engineered constructs with cultured endothelial progenitor cells (EPCs) for enhancing bone regeneration have not been reported. In this study, we investigated the potential of EPCs to facilitate neovascularization in implants and evaluated their influence on bone regeneration. The influence of EPC soluble factors on osteogenic differentiation of mesenchymal stem cells (MSCs) was tested by adding EPC culture supernatant to MSC culture medium. To evaluate the influence of EPCs on MSC osteogenesis, canine MSCs‐derived osteogenic cells and EPCs were seeded independently onto collagen fiber mesh scaffolds and co‐transplanted to nude mice subcutaneously. Results from coimplant experiments were compared to implanted cells absent of EPCs 12 weeks after implantation. Factors from the culture supernatant of EPCs did not influence MSC differentiation. Coimplanted EPCs increased neovascularization and the capillary score was 1.6‐fold higher as compared to the MSC only group (p < 0.05). Bone area was also greater in the MSC + EPC group (p < 0.05) and the bone thickness was 1.3‐fold greater in the MSC + EPC group than the MSC only group (p < 0.05). These results suggest that soluble factors generated by EPCs may not facilitate the osteogenic differentiation of MSCs; however, newly formed vasculature may enhance regeneration of tissue‐engineered bone. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Acute paraplegia in a patient with AIDS and a normal CSF examination
Authors: Lunn M. P. T. , Clarke C. , Aldeen T.
Published: June 2008

We report a case of tuberculous myeloradiculitis in a patient with AIDS. The case highlights the difficulty in reaching a diagnosis for the neurological symptoms of a patient with a normal CSF examination and the need for HIV screening of immune‐compromised patients with myeloradiculitis. Journal of Hospital Medicine 2008;3:279–280. © 2008 Society of Hospital Medicine.
Sleepiness in critical care nurses: Results of a pilot study
Authors: Surani Salim , Subramanian Shyam , Babbar Harsh , Murphy Jane , Aguillar Raymond
Published: June 2008

BACKGROUND:

Sleep deprivation, compounded by circadian disruptions, is a common problem in health care workers. Sleepiness in nurses has important implications for patients as well as nurses' own safety.

OBJECTIVE:

The objective of the study was to assess comprehensively sleepiness levels in post‐night‐shift nurses.

METHODS:

Post‐night‐shift nurses in the ICU and on general floors (medicine and surgery) were assessed using subjective (Epworth Sleepiness Scale [ESS]) and objective (Mean Sleep Latency Test [MSLT]) measures.

RESULTS:

ESS was abnormal (>8) in 7 of 10 ICU nurses compared with 2 of 10 floor nurses (P < .005), and mean ESS score was also higher (8.7 ± 3.9 vs. 5.6 ± 2.1, respectively; P = 0.042). MSLT values for the first nap period were in the pathologic range in the ICU nurses compared with the floor nurses (4.65 ± 5.5 vs. 10.85 ± 7.4 minutes, respectively; P < .05).

CONCLUSIONS:

Post‐night‐shift RNs working in the ICU have a pathologic degree of sleepiness. Journal of Hospital Medicine 2008;3:200–205. © 2008 Society of Hospital Medicine.
Influence of physician specialty on outcomes after acute ischemic stroke
Authors: Gillum Leslie Allison , Johnston S. Claiborne
Published: June 2008

BACKGROUND:

Specialist care has been shown to improve outcomes for several complex medical conditions. For patients with ischemic stroke, prior studies have suggested that admission to the care of neurologists is associated with better outcomes, but these studies may have incompletely controlled for confounding prognostic differences.

OBJECTIVE:

The objective of this study was to evaluate whether admission to the care of a neurologist is associated with improvement in outcomes of stroke patients after controlling for initial prognostic differences.

DESIGN:

This was a retrospective cohort study.

SETTING:

Participating in the study were 113 U.S. academic hospitals.

PATIENTS:

Demographic and clinical data for all ischemic stroke patients admitted through emergency departments from 1997 to 1999 were collected from an administrative database.

MEASUREMENTS:

In traditional analyses, we evaluated attending physician specialty as a predictor of in‐hospital mortality. In grouped‐treatment (GT) analyses, a method based on the instrumental variable approach that bypasses selection bias, the hospital rate of stroke admission to neurologists was used as the predictor. We used generalized estimating equations for all analyses, adjusting for demographics, urgency, comorbid illness severity, and treatment volume.

RESULTS:

Of 26,925 ischemic stroke patients, 60% were admitted to the care of neurologists. In univariate analysis, risk of in‐hospital mortality in cases admitted to neurologists (4.6%) was lower than that for those admitted to generalists (9.5%; P < .001). Adjustment for individual‐level characteristics did not alter the association (0.60 OR, 95% CI, 0.50–0.72; P < .001). However, no advantage to neurologist admission was demonstrated in GT analysis, with mortality rates similar at hospitals admitting different proportions of ischemic stroke cases to neurologists (1.02 OR, 95% CI, 0.79–1.30; P = .90).

CONCLUSIONS:

Differences in ischemic stroke outcomes between neurologists and generalists may be a result of differences in initial prognosis because outcomes are no better at hospitals that admit patients to the care of neurologists more frequently. Journal of Hospital Medicine 2008;3:184–192. © 2008 Society of Hospital Medicine.
History of mass spectrometry at the Olympic Games
Authors: Hemmersbach Peter
Published: June 2008

Mass spectrometry has played a decisive role in doping analysis and doping control in human sport for almost 40 years. The standard of qualitative and quantitative determinations in body fluids has always attracted maximum attention from scientists. With its unique sensitivity and selectivity properties, mass spectrometry provides state‐of‐the‐art technology in analytical chemistry. Both anti‐doping organizations and the athletes concerned expect the utmost endeavours to prevent false‐positive and false‐negative results of the analytical evidence.

The Olympic Games play an important role in international sport today and are milestones for technical development in doping analysis. This review of the part played by mass spectrometry in doping control from Munich 1972 to Beijing 2008 Olympics gives an overview of how doping analysis has developed and where we are today.

In recognizing the achievements made towards effective doping control, it is of the utmost importance to applaud the joint endeavours of the World Anti‐Doping Agency, the International Olympic Committee, the international federations and national anti‐doping agencies to combat doping. Advances against the misuse of prohibited substances and methods, which are performance‐enhancing, dangerous to health and violate the spirit of sport, can be achieved only if all the stakeholders work together. Copyright © 2008 John Wiley & Sons, Ltd.
Physical Gelation of Amphiphilic Poly(N‐isopropylacrylamide): Influence of the Hydrophobic Groups
Authors: Wintgens Véronique , Amiel Catherine
Published: June 2008

The self‐assembling properties of hydrophobically modified (N‐isopropylacrylamide) have been investigated by dynamic light scattering and rheological measurements. Size of the globules and transmission of the solutions vary strongly in the same range of temperature. The presence of hydrophobic groups leads to contraction of the globules' size compared to poly(N‐isopropylacrylamide) (PNIPAM). The viscoelastic properties of the samples in aqueous solution have been investigated as a function of copolymer concentration, structure of the hydrophobic group (dodecyl or adamantyl group), substitution level (1–5%) and over a temperature range covering the lower critical solution temperature (LCST). At high concentration and high level of adamantyl substitution, gelation is observed several degrees before the phase transition. A physical network is formed due to the strong hydrophobic interactions, and this physical gel undergoes phase transition without macroscopic phase separation.

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Contractive Polymeric Complex Micelles as Thermo‐Sensitive Nanopumps
Authors: Wang Huan , An Yingli , Huang Nan , Ma Rujiang , Li Junbo , Shi Linqi
Published: June 2008

Complex micelles were obtained from PS‐b‐PNIPAM‐b‐PAA micelles and PEG‐b‐P4VP block copolymers via the strong electrostatic interaction and hydrogen bonding between PAA and P4VP blocks in water. The PS block formed the core and the PAA/P4VP complex shell functioned as a semi‐permeable membrane which could control the permeation of small molecules. Between the core and shell, the large fluid‐filled space that was formed with the thermoresponsive PNIPAM gel could retain the loaded drug for a long period of time. With increasing temperature, the shrinkage of the PNIPAM coils pumped the drug out of the complex micelles. The complex micelles functioned as a contractive “nanopump”, which could potentially be applied as a thermosensitive controlled release system.

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A Methodology for Investigating Protein Adhesion and Adsorption to Microarrayed Combinatorial Polymers
Authors: Taylor Michael , Urquhart Andrew J. , Anderson Daniel G. , Williams Philip M. , Langer Robert , Alexander Morgan R. , Davies Martyn C.
Published: June 2008

Here, we report the use of fluorescently labelled proteins to study protein adsorption to microarrayed synthetic polymers for the first time, indicating that this method is appropriate for the study of protein adsorption on these arrays. To investigate protein adhesion directly we use atomic force microscopy (AFM) to measure the force of adhesion between a protein‐coated probe and the arrayed polymers. Both approaches show promise as methods for screening protein interactions with polymers in a microarray format. Comparison of these very different measures of protein–surface interactions indicate a good correlation.

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Supramolecular Nanoscaled Self‐Assembly of Bifunctional Cyclodextrin and Trifunctional Melamine Precursors
Authors: Choi Sung‐Ho , Jung Hyun‐Ho , Kim Jae‐Il , Furusho Horotoshi , Geckeler Kurt E
Published: June 2008

A new type of guest–core supramolecular networks via inclusion complexation of nanoscaled building blocks such as bifunctional cyclodextrin (CD) derivatives and trifunctional melamine derivatives were prepared. By using AFM and an adoption of the cryo‐TEM technique under high acceleration voltage the nanoscale supramolecular network structure, nexus units, and CD molecules could be visualized. In addition to the 2‐D 1H NMR rotating frame Overhauser effect spectroscopy (ROESY) experiments, theoretical studies on the molecular docking of the CDs and the melamine derivative have been conducted to elucidate the thermodynamic properties by the two‐layered integrated molecular orbital and molecular mechanics (ONIOM) method, which combines both quantum mechanics and molecular mechanics (QM/MM) calculations.

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Engineering of Covalently Immobilized Gradients of RGD Peptides on Hydrogel Scaffolds: Effect on Cell Behaviour
Authors: Guarnieri Daniela , Borzacchiello Assunta , De Capua Antonia , Ruvo Menotti , Netti Paolo A.
Published: June 2008

Summary:The aim of this study has been to design a system for the preparation of Polyethylene‐glycol (PEG) based hydrogels with a controlled spatial distribution of covalently immobilised RGD adhesion signals in order to control and guide cell response for tissue engineering application. Gradients of immobilised RGD peptides were characterized by confocal microscopy analysis. Moreover, the effect of RGD spatial distribution on cell behaviour was evaluated by using mouse embryo fibroblasts NIH3T3. In particular, we observed cell adhesion and migration of fibroblasts seeded on RGD gradient compared to cells on control hydrogels having an uniform distribution of RGD. Our data suggest that a linear gradient of covalently immobilised adhesion signals affects cell behaviour. In particular, cells feel RGD gradient and oriented themselves and move along gradient direction.
Determination of Water and Solute Transport in Polyacrylamide Gels
Authors: Brahm Jesper , Lessel Robert , Ditlev Sisse , Schmidt Richard
Published: June 2008

Summary:Water exchange between five polyacrylamide gels (Bulkamid®, Aquamid®, Rectamid®, HV‐PAAG, Acuvue) with a physiological salt solution was determined by means of tritium‐labeled water. Urea and chloride exchange was also determined in Acuvue. The method was a modified version to measure rapid transport processes in red blood cells. The study shows that water and solutes easily exchange between the hydrogel under study and the surrounding medium, independent of the solid polymer content (2.5–40 wt%) and an over ten‐fold variation of the cross‐linking density.
The invisible reality of arthritis: A qualitative analysis of an online message board
Authors: Hadert Aimee , Rodham Karen
Published: June 2008

Background and aim: Living with a chronic illness, such as arthritis, creates many psychosocial stressors, which can be difficult to cope with. Exploring the interactions which take place on an online message board for people with arthritis may provide insight into both the social support offered, as well as highlighting the groups' needs that perhaps are not being met in a more formal ‘offline’ setting. The aim of this study was to investigate how and why an arthritis online message board was used.

Methods: A retrospective three‐month period of discussions posted on an online message board for people who have arthritis was downloaded into a word document. Collecting data in this manner ensured that completed discussions were captured. Eighty‐seven initial messages and 981 replies were analysed. The discussions were analysed using interpretive phenomenological analysis.

Results: Four master themes were identified. Firstly, the invisible reality of the condition; secondly, information exchange, whereby users of the message board were shown to be both seeking and providing information; thirdly, while users praised the support they received from family and friends, the support offered and received online was considered to provide additional benefits. Finally, the message board allowed users to share (primarily negative) emotions which they felt unable to express in their offline worlds.

Conclusion and implications: Patients do not always understand the information being offered by health care professionals, and they do not have the confidence to ask for clarification. Health care professionals need to ensure that they find a way of checking levels of patient understanding. Failure to do so means that patients may turn to alternative sources, which may not provide accurate information. The study also showed that people with arthritic conditions find it difficult to express how they are feeling in their offline world; furthermore, they find it difficult to ask for support from their significant others, preferring instead to ‘suffer in silence’ and seek support from the online community, potentially further isolating them from the support of those in their offline world. There is scope for such patients to be both empowered and educated, so that they are better able to ask for the help they need, which in turn will help to counteract the danger of isolation. Copyright © 2008 John Wiley & Sons, Ltd.
Step size adjustment and extrapolation for time‐stepping schemes in non‐smooth dynamics
Authors: Studer C. , Leine R. I. , Glocker Ch.
Published: June 2008

In this paper we use step size adjustment and extrapolation methods to improve Moreau's time‐stepping scheme for the numerical integration of non‐smooth mechanical systems, i.e. systems with impact and friction. The scheme yields a system of inclusions, which is transformed into a system of projective equations. These equations are solved iteratively. Switching points are time instants for which the structure of the mechanical system changes, for example, time instants for which a sticking friction element begins to slide. We show how switching points can be localized and how these points can be resolved by choosing a minimal step size. In order to improve the integration of non‐smooth systems in the smooth parts, we show how the time‐stepping method can be used as a base integration scheme for extrapolation methods, which allow for an increase in the integration order. Switching points are processed by a small time step, while time intervals during which the structure of the system does not change are computed with a larger step size and improved integration order. The overall algorithm, which consists of a time‐stepping module, an extrapolation module and a step size adjustment module, is discussed in detail and some examples are given. Copyright © 2008 John Wiley & Sons, Ltd.
Experimental characterization and morphology investigation of composites based on high‐density and low‐density polyethylene reinforced with non‐crimp‐stitched glass fabrics
Authors: Sarıkanat Mehmet , Çeçen Volkan , Erden Seçkin , Baltacı Aysun
Published: June 2008

In this study, the effects of matrix material on mechanical properties were investigated in glass fiber reinforced high‐density and low‐density polyethylene composites. Also, in order to compare the fiber configuration effect on anisotropic behavior, unidirectional and biaxial glass fabrics were used as reinforcement material. Composite laminates were manufactured via the compression molding technique. Tensile and three‐point bending flexural tests were conducted up to failure on specimens cut out in different directions. Extensive fracture photomicrographs were presented for observing the failure modes (e.g. delamination) of the composites resulting from a variety of loading conditions. In addition, Scanning electron micrographs of postfractured surfaces of composites were interpreted in an attempt to explain the failure mechanisms (adhesive or cohesive failure) of the composites. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers
Preparation and mechanical properties of waterborne polyurethane/carbon nanotube composites
Authors: Zhao Cai‐Xia , Zhang Wei‐De , Sun Dong‐Cheng
Published: June 2008

Waterborne polyurethane (WBPU) and multiwalled carbon nanotubes (CNTs) composite films with 0–4.0 wt% CNTs were prepared by ultrasonic dispersion of carboxylic acid‐functionalized CNTs in WBPU followed by emulsion casting process. The elongations at break of the WBPU/CNTs composites increase with the incorporation of CNTs. The tensile strength and crystallinity of the nanocomposite films with lower CNTs contents (<2 wt%) increase obviously; while the tensile strengths of the composites with more CNTs (≥2 wt%) decrease, in contrast to the pure PU film. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations indicated that the CNTs are uniformly dispersed in the composites incorporated with lower CNTs contents (≤1.5 wt%). However, aggregation of CNTs increased with increasing CNTs content in the WBPU/CNTs composites, causing the macrophase separation. The dispersion state of the CNTs affects the crystallinity of the PU matrix and the phase separation of the composites, which are two key factors to influence the mechanical properties of the WBPU/CNTs composites. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
Deterioration in mechanical properties of glass fiber‐reinforced nylon 6,6 composites by aqueous calcium chloride mixture solutions
Authors: Dhevi D. Manjula , Choi Chang Woo , Prabu A. Anand , Kim Kap Jin
Published: June 2008

In this article, nylon 6,6 (NY66) and glass fiber‐(30 wt%) reinforced NY66 (GFNY66) specimens were immersed in various aqueous calcium chloride (aq. CaCl2) mixture solutions at different thermal conditions for varying intervals of time, and analyzed using attenuated total reflection‐infrared (ATR‐IR) spectroscopy, inductively coupled plasma (ICP), energy dispersive X‐ray (EDX), gel permeation chromatography (GPC), and mechanical studies. ICP data revealed increasing concentration of absorbed Ca2+ ions with increasing immersion time resulting in disruption of intra‐ and intermolecular H‐bonding as confirmed using ATR‐IR results. From EDX data, the ratio of Ca2+ and Cl− ions absorbed by NY66 was calculated and found to follow its stoichiometric equivalence. GPC data exhibited less reduction in Mn and Mw for aq. CaCl2‐treated NY66 specimens suggesting the absence of any significant chemical degradation, but the occurrence of only physical changes involving H‐bond breakage and the formation of new CO···Ca2+ dative bond in NY66 matrix. The mechanical properties of GFNY66 samples treated with various types of aq. CaCl2 solutions exhibited pronounced deterioration, possibly due to the interfacial failure between glass fiber and NY66 matrix. The results obtained from this study were quite useful toward understanding the degradation mechanism in NY66 and GFNY66 caused by various aq. CaCl2 mixture solutions, and will be helpful in improving the mechanical properties of recycled NY66. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
Toughness and reinforcement of diglycidyl ether of bisphenol‐A by hyperbranched poly(trimellitic anhydride‐butanediol glycol) ester epoxy resin
Authors: Zhang Daohong , Chen Yukun , Jia Demin
Published: June 2008

Hyperbranched epoxy resin shows best comprehensive performance in epoxy resin system and is considered as a kind of toughness and reinforcement additive. This article reports on the use of novel hyperbranched poly(trimellitic anhydride‐butanediol glycol) ester epoxy resin (HTBE) prepared by us as a functional additive to an epoxy amine resin system. The effect of molecular weight and content of the HTBE on the performance of the diglycidyl ether of bisphenol‐A (DGEBA)/HTBE hybrid resin are discussed in detail, and their performance has maximum with the increase of content and molecular weight of HTBE. The impact strength and fracture toughness of the hybrid resin containing 9 wt% second generation of HTBE are 48.2 kJ/m2 and 2.71 MPa m1/2, and which almost are 2.77 and 1.5 times of DGEBA performance respectively. Furthermore, the tensile and flexural strength can also be enhanced about 17%. The fracture surface micrograph of hybrid resin shows no microphase separation of the HTBE/DGEBA blends that facilitates an enhanced interaction to achieve excellent toughness and strength enhancement of the cured systems by scanning electron microscope (SEM). A novel situ reinforcing and toughening mechanism and model are discovered and confirmed by SEM, molecular simulation, and dynamic mechanical thermal analysis technology. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
High‐performance composite from epoxy and glass fibers: Morphology, mechanical, dynamic mechanical, and thermal analysis
Authors: Hameed Nishar , Sreekumar P.A. , Valsaraj V.S. , Thomas Sabu
Published: June 2008

Diglycidyl ether of bisphenol‐A type epoxy resin cured with diamino diphenyl sulfone was used as the matrix for fiber‐reinforced composites to get improved mechanical and thermal properties for the resulting composites. E‐glass fiber was used for fiber reinforcement. The morphology, tensile, flexural, impact, dynamic mechanical, and thermal properties of the composites were analyzed. The tensile, flexural, and impact properties showed dramatic improvement with the addition of glass fibers. Dynamic mechanical analysis was performed to obtain the Tg of the cured matrix as well as the composites. The improved thermal stability of the composites was clear from the thermogravimetric analysis. Scanning electron micrographs were taken to understand the interfacial adhesion between the fiber and the matrix. The values of mechanical properties were compared with modified epoxy resin composite system. Predictive models were applied using various equations to compare the mechanical data obtained theoretically and experimentally. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers