bluuebunny/crossref_metadata_2025 huggingface dataset:
Activation of dorsal horn microglia contributes to diabetes‐induced tactile allodynia via extracellular signal‐regulated protein kinase signaling
Authors: Tsuda Makoto , Ueno Hikaru , Kataoka Ayako , Tozaki‐Saitoh Hidetoshi , Inoue Kazuhide
Published: January 2008

Painful neuropathy is one of the most common complications of diabetes, one hallmark of which is tactile allodynia (pain hypersensitivity to innocuous stimulation). The underlying mechanisms of tactile allodynia are, however, poorly understood. Emerging evidence indicates that, following nerve injury, activated microglia in the spinal cord play a crucial role in tactile allodynia. However, it remains unknown whether spinal microglia are activated under diabetic conditions and whether they contribute to diabetes‐induced tactile allodynia. In the present study, using streptozotocin (STZ)‐induced diabetic rats that displayed tactile allodynia, we found several morphological changes of activated microglia in the dorsal horn. These included increases in Iba1 and OX‐42 labeling (markers of microglia), hypertrophic morphology, the thickness and the retraction of processes, and in the number of activated microglia cells. Furthermore, in the dorsal horn of STZ diabetic rats, extracellular signal‐regulated protein kinase (ERK) and an upstream kinase, Src‐family kinase (SFK), both of which are implicated in microglial functions, were activated exclusively in microglia. Moreover, inhibition of ERK phosphorylation in the dorsal horn by intrathecal administration of U0126, an inhibitor of ERK activation, produced a striking alleviation of existing, long‐term tactile allodynia of diabetic rats. We also found that a single administration of U0126 reduced the expression of allodynia. Together, these results suggest that activated dorsal horn microglia may be a crucial component of diabetes‐induced tactile allodynia, mediated, in part, by the ERK signaling pathway. Thus, inhibiting microglia activation in the dorsal horn may represent a therapeutic strategy for treating diabetic tactile allodynia. © 2008 Wiley‐Liss, Inc.
Renal effects of long‐term lithium therapy in the elderly: a cross‐sectional study
Authors: van Melick Els J. M. , Meinders Arend E. , Hoffman Tonko O. , Egberts Toine C. G.
Published: January 2008

Objectives

To determine the effect of long‐term lithium therapy on glomerular filtration rate (GFR) and maximum renal concentrating capacity (Umax) in the elderly, to identify possible risk factors, to determine the clinical impact of a reduced Umax in this population and in case of polyuria to establish a diagnosis.

Methods

This is a cross‐sectional study with 48 outpatients of 65 years or over (mean 74.8 years), who were treated with lithium for more than 6 months (mean 9.2 years). The GFR was determined with the Cockcroft‐Gault formula (GFR‐CG) and the Umax was measured in a urine sample collected between 3 and 5 h after the patients received 40 μg desmopressin (DDAVP) intranasally.

Results

No relation was found between duration of lithium treatment and GFR‐CG, but there was a significant negative relation between duration of lithium treatment and Umax (B −0.73; CI: −1.249/−0.212); 73% of the patients had a moderate to severe concentrating defect. No other risk factors than duration of lithium therapy were identified. A reduced Umax caused polyuria (>2500 mL/24 h) in 33% but did not cause significant more thirst, incontinence or disturbed sleep.

Conclusions

In this geriatric population a negative relation was found between duration of lithium treatment and Umax. But a reduced Umax did not result in significant more clinical symptoms. In case of polyuria other mechanisms beside nephrogenic diabetes insipidus were found to play a role in this age group. Copyright © 2008 John Wiley & Sons, Ltd.
Modification and testing of a one‐dimensional energy and mass balance model for supraglacial snowpacks
Authors: Fox Andrew M. , Willis Ian C. , Arnold Neil S.
Published: January 2008

A one‐dimensional energy and mass balance snow model (SNTHERM) has been modified for use with supraglacial snowpacks and applied to a point on Haut Glacier d'Arolla, Switzerland. It has been adapted to incorporate the underlying glacier ice and a site‐specific, empirically derived albedo routine. Model performance was tested against continuous measurements of snow depth and meltwater outflow from the base of the snowpack, and intermittent measurements of surface albedo and snowpack density profiles collected during the 1993 and 2000 melt seasons. Snow and ice ablation was simulated accurately. The timing of the daily pattern of meltwater outflow was well reproduced, although magnitudes were generally underestimated, possibly indicating preferential flow into the snowpack lysimeter. The model was used to assess the quantity of meltwater stored temporally within the unsaturated snowpack and meltwater percolation rates, which were found to be in agreement with dye tracer experiments undertaken on this glacier. As with other energy balance studies on alpine valley glaciers, the energy available for melt was dominated by net radiation (64%), with a sizable contribution from sensible heat flux (36%) and with a negligible latent heat flux overall, although there was more complex temporal variation on diurnal timescales. A basic sensitivity analysis indicated that melt rates were most sensitive to radiation, air temperature and snowpack density, indicating the need to accurately extrapolate/interpolate these variables when developing a spatially distributed framework for this model. Copyright © 2008 John Wiley & Sons, Ltd.
Design and field tuning of an upstream controlled canal network SCADA
Authors: Rijo M.
Published: January 2008

This paper presents the design, implementation and field tuning of a SCADA of an irrigation canal network upstream controlled with AMIL gates and equipped with other Neyrpic devices. Besides the hydraulic system, the paper also presents the supervisory and control system and its remote terminal units. The developed and field‐tuned manual and automatic controllers are also presented. The manual controllers – direct and gate position controllers and gate flow controllers – are defined for the main canal intakes in order to permit achievement of predefined flow values or daily flow schedules, and are also defined for a few gate‐controlled canal orifices used to discharge the overflow to the drainage system. The automatic controllers – water depth controllers for a few gate‐controlled canal orifices – are defined in order to automatically prevent canal overtopping.

The SCADA system also monitors the outflows at the main canals – the most important canal top side weirs, canal terminal weirs and automatic Neyrpic siphons. The flow equations used in the computing of flow in real time inside the developed controllers and the monitoring units were field tuned using collected data readings from a monostatic Doppler current meter. The tuning parameters are also defined and presented. Copyright © 2008 John Wiley & Sons, Ltd.
Helical domain collagen substrates mineralization in simulated body fluid
Authors: Falini Giuseppe , Fermani Simona , Palazzo Barbara , Roveri Norberto
Published: January 2008

Helical domain collagen substrates had been mineralized using simulated body fluid. They had an increasing level of structural organization; being in the form of gel, film, and uniaxial deformed film. The experiments were carried out for different periods of time and the obtained composite materials were characterized in their mineral content. Apatite precipitation was detected. The results show that the helical domain collagen substrates partially inhibit the in vitro apatite precipitation processes, but the amount and the crystallinity of deposited mineral can be controlled by the different assemblies of the helical domain collagen fibers. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Biocompatibility of a functionally graded bioceramic coating made by wide‐band laser cladding
Authors: Weidong Zhu , Qibin Liu , Min Zheng , Xudong Wang
Published: January 2008

The application of plasma spray is the most popular method by which a metal‐bioceramic surface composite can be prepared for the repair of biological hard‐tissue, but this method has disadvantages. These disadvantages include poor coating‐to‐substrate adhesion, low mechanical strength, and brittleness of the coating. In the investigation described in this article, a gradient bioceramic coating was prepared on a Ti‐6Al‐4V titanium alloy surface using a gradient composite design and wide‐band laser cladding techniques. Using a trilayer‐structure composed of a substratum, an alloy and bioceramics, the coating was chemically and metallurgically bonded with the substratum. The coating, which contains β‐tricalcium phosphate and hydroxyapatite, showed favorable biocompatibility with the bone tissue and promoted in vivo osteogenesis. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Guided growth of smooth muscle cell on poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate) scaffolds with uniaxial microtubular structures
Authors: Chen Song , Wang Pei‐Pei , Wang Jin‐Peng , Chen Guo‐Qiang , Wu Qiong
Published: January 2008

Scaffolds of biopolyester poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate) (PHBHHx) with uniaxial microtubular structure were successfully prepared by directional freezing and phase‐separation techniques. These special structures guided the rabbit aorta smooth muscle cells (RaSMCs) to grow along the tubular structure. The structure of the scaffolds including tubular size and architecture, as well as scaffold mechanical properties could be adjusted by changing the PHBHHx concentration, PHBHHx solvent, and phase‐separation temperature. In addition, the scaffolds demonstrated anisotropic mechanical properties, with much more improved strength along the longitudinal direction of the microtubules compared with those along the transverse direction. Three‐day and 7‐day cell culture of RaSMCs seeded on the scaffolds with different microtubular sizes showed similar cellular metabolic activity but different cell distribution and morphology owing possibly to different scaffold tubular sizes. The scanning electron microscopy and H&E staining demonstrated that RaSMCs were guided to grow along the microtubular structures of scaffolds prepared from the 2.5% or 3.0% PHBHHx/benzene solution. This study demonstrated the possibility of using PHBHHx scaffolds to achieve guided cell growth. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
A preliminary study on MeO‐PEG‐PLGA‐PEG‐OMe nanoparticles as intravenous carriers
Authors: Duan Yourong , Xu Jinping , Lin Yunzhu , Yu Hui , Gong Tao , Li Yaogang , Zhang Zhirong
Published: January 2008

To develop an intravenous nanoparticle delivery system for a cancer drug (i.e., DHAQ, mitoxantrone), the synthesis of a biodegradable polyester polymer with hydrophilic polyethylene glycol chains, preparation of DHAQ‐loaded nanoparticles from such polymer and biodistribution of the drug‐loaded particles were investigated in this article. Biodegradable monomethoxy poly(ethylene glycol)‐poly (lactide‐co‐glycolide)‐monomethoxy poly(ethylene glycol) (MeO‐PEG‐PLGA‐PEG‐OMe, PELGE) copolymers were synthesized by ring‐opening polymerization as the drug carriers. A double emulsion method with dextran‐70 as an emulsifier was employed to prepare the nanoparticles. DHAQ‐PELGE nanoparticles and free DHAQ were employed for the in vivo biodistribution studies after intravenous administration through the tail veins in mice. At various time intervals, the mice were sacrificed and several organs and tissues harvested, including hearts, livers, spleens, lungs, kidneys, and blood. The DHAQ concentrations in the collected tissues and plasmas were determined using high performance liquid chromatography. The DHAQ concentrations in mice plasmas in the experimental groups were significantly higher than those in the control group and 3.72% of total administrations dosages (TAD) of these particles with DHAQ remained in circulation even 96 h after intravenous injection. Compared with the free DHAQ, DHAQ‐loaded PELGE nanoparticles had longer circulation properties. Further research should be done for intravenous injection of this material as drug carriers. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Primary sequence of ionic self‐assembling peptide gels affects endothelial cell adhesion and capillary morphogenesis
Authors: Sieminski A. L. , Semino C. E. , Gong H. , Kamm R. D.
Published: January 2008

Appropriate choice of biomaterial supports is critical for the study of capillary morphogenesis in vitro as well as to support vascularization of engineered tissues invivo. Self‐assembling peptides are a class of synthetic, ionic, oligopeptides that spontaneously assemble into gels with an ECM‐like microarchitecture when exposed to salt. In this paper, the ability of four different self‐assembling peptide gels to promote endothelial cell adhesion and capillary morphogenesis is explored. Human umbilical vein endothelial cells (HUVECs) were cultured within ionic self‐assembling peptide family members, RAD16‐I ((RADA)4), RAD16‐II ((RARADADA)2), KFE‐8 ((FKFE)2), or KLD‐12 ((KLDL)3). HUVECs suspended in RAD16‐I or RAD16‐II gels elongated and formed interconnected capillary‐like networks resembling in vivo capillaries, while they remained round and formed clusters within KFE‐8 or KLD‐12 gels. As HUVECs attach to RAD16‐I and RAD16‐II significantly better than the other peptides, these differences appear to be explained by differences in cell adhesion. Although adhesion likely occurs via bound adhesion proteins, there appears to be no difference in protein binding to the peptides investigated. Results indicate that, although these oligopeptides have similar mechanisms of self‐ assembly, their primary sequence can greatly affect cell adhesion. Additionally, a subset of these biomimetic ECM‐like materials support capillary morphogenesis and thus may be useful for supporting vascularization. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Evaluation of cell affinity on poly(L‐lactide) and poly(ε‐caprolactone) blends and on PLLA‐b‐PCL diblock copolymer surfaces
Authors: Ajami‐Henriquez Diana , Rodríguez Mónica , Sabino Marcos , Castillo R. Verónica , Müller Alejandro J. , Boschetti‐de‐Fierro Adriana , Abetz Clarissa , Abetz Volker , Dubois Philippe
Published: January 2008

An evaluation of cell proliferation and adhesion on biocompatible film supports was performed. A series of films were compression molded from commercially available poly (L‐lactide), PLLA, and poly(ε‐caprolactone), PCL, and from their melt mixed blends (PLLA/PCL blends). These were compared with compression molded films of PLLA‐b‐PCL model diblock copolymers. The samples were analyzed by differential scanning calorimetry (DSC), contact angle measurements, and scanning force microscopy (SFM). Cell adhesion and proliferation were performed with monkey derived fibroblasts (VERO) and with osteoblastic cells obtained either enzymatically or from explants cultures of Sprague–Dawley rat calvaria. Migration studies were performed with bone explants of the same origin. The results obtained indicate that although all materials tested were suitable for the support of cellular growth, a PLLA‐b‐PCL diblock copolymer sample with 93% PLLA was significantly more efficient. This sample exhibited a unique surface morphology with long range ordered domains (of the order of 2–3 μm) of edge‐on PLLA lamellae that can promote “cell contact guidance.” The influence of other factors such as chemical composition, degree of crystallinity, and surface roughness did not play a major role in determining cell preference toward a specific surface for the materials employed in this work. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Study on the biocompatibility of novel terpolyester poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate‐co‐3‐hydroxyhexanoate)
Authors: Liang Yan‐Sheng , Zhao Wei , Chen Guo‐Qiang
Published: January 2008

Terpolyester poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate‐co‐3‐hydroxyhexanoate) (PHBVHHx) containing 5.3 mol % 3‐hydroxyvalerate (3‐HV) and 10.2 mol % 3‐hydroxyhexanoate was obtained via microbial synthesis using recombinant Aeromonas hydrophila. For the first time in vitro biocompatibility of the terpolyester was evaluated in comparison with poly(L‐lactic acid), poly (3‐hydroxybutyrate), poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate), and poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate) (PHBHHx). Scanning electron microscopy showed whorls‐like morphology only on PHBVHHx film surface. Methylthiazol tetrazolium assay demonstrated that PHBVHHx was better than the above four materials in promoting cell attachment and proliferation of fibroblast cell line L929 and osteoblast cell line MC3T3, respectively. Histological study using rabbits proved that PHBVHHx was a fairly harmless implantable biomaterial. Thus, PHBVHHx with an adjustable mechanical properties, combined with its biocompatibility, are in the process of developing into a new generation of bioimplant material. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Enhanced chondrocyte densities on carbon nanotube composites: The combined role of nanosurface roughness and electrical stimulation
Authors: Khang Dongwoo , Park Grace E. , Webster Thomas J.
Published: January 2008

Simultaneous incorporation of intrinsic nanosurface roughness and external electrical stimulation may maximize the regeneration of articular cartilage tissue more than on nanosmooth, electrically nonstimulated biomaterials. Here, we report enhanced functions of chondrocytes (cartilage synthesizing cells) on electrically and nonelectrically stimulated highly dispersed carbon nanotubes (CNT) in polycarbonate urethane (PCU) compared to, respectively, stimulated pure PCU. Specifically, compared to conventional longitudinal (or vertical) electrical stimulation of chondrocytes on conducting surfaces which require high voltage, we developed a lateral electrical stimulation across CNT/PCU composite films of low voltage that enhanced chondrocyte functions. Chondrocyte adhesion and long‐term cell densities (up to 2 days) were enhanced (more than 50%) on CNT/PCU composites compared to PCU alone without electrical stimulation. This study further explained why by measuring greater amounts of initial fibronectin adsorption (a key protein that mediates chondrocyte adhesion) on CNT/PCU composites which were more hydrophilic (than pure PCU) due to greater nanometer roughness. Importantly, the same trend was observed and was even significantly enhanced when chondrocytes were subjected to electrical stimulation (more than 200%) compared to nonstimulated CNT/PCU. For this reason, this study provided direct evidence of the positive role that conductive CNT/PCU films can play in promoting functions of chondrocytes for cartilage regeneration. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
In vitro evaluation of nanosized carbonate‐substituted hydroxyapatite and its polyhydroxyethylmethacrylate nanocomposite
Authors: Huang J. , Best S. M. , Brooks R. A. , Rushton N. , Bonfield W.
Published: January 2008

Nanometer scale carbonate‐substituted hydroxyapatite (nanoCHA) particles were prepared and examined using transmission electron microscopy, which revealed their polycrystalline nature with a rod‐like morphology (20–30 nm in width and 50–80 nm in length). In vitro cytotoxicity study showed that there was some evidence of lactate dehydrogenase (LDH) release when macrophages were in contact with high concentrations of nanoCHA particles. The levels of LDH release decreased significantly with a reduction in nanoCHA concentration. A similar trend was observed for the inflammatory cytokine TNF‐α. nanoCHA particles with high carbonate content induced a high level of TNF‐α release. Biological testing using a human osteoblast (HOB) cell model found that HOB cells were able to grow and proliferate on a nanoCHA deposited surface. Well organized actin fibers were observed for HOB cells in contact with nanoCHA particles with low carbonate content and the cell proliferation rate was higher on these particles in comparison with those of high carbonate nanoCHA particles. Therefore, low carbonate nanoCHA particles were incorporated into poly‐(2‐hydroxyethylmethacrylate) matrix to make a nanocomposite. It was found that the nanoCHA composite was hydrophilic and became rubber‐like after hydration. Both 20 wt % and 40 wt % composites were able to induce the formation of bone‐like apatite after immersion in simulated body fluid. A high bioactivity of the composite was obtained with high loading of the nanoCHA filler. These results demonstrate the potential of formulating nanocomposites for biomedical applications. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
In vitro oxidation of high polydimethylsiloxane content biomedical polyurethanes: Correlation with the microstructure
Authors: Hernandez Rebeca , Weksler Jadwiga , Padsalgikar Ajay , Runt James
Published: January 2008

The resistance to in vitro metal ion oxidation of a polydimethylsiloxane (PDMS)‐containing thermoplastic polyurethane elastomer (Elast‐Eon™) is compared with that of a polyurethane consisting of the same hard segment chemistry and content, but with aliphatic polycarbonate soft segments (PCU). Scanning electron microscopy and attenuated total reflectance Fourier transform infrared spectroscopy were used to assess changes in surface morphology and chemistry. The extent of bulk degradation was assessed indirectly by dynamic mechanical analysis and small‐angle X‐ray scattering experiments. The findings indicate that Elast‐Eon™ is more resistant to oxidation than the PCU, because of the presence of the PDMS soft segments as well as its phase separated microstructure. The PCU exhibits a rather high degree of intermixing between hard and soft segments, rendering the hard segments dissolved or trapped in the soft phase more susceptible to oxidative conditions. By contrast, we propose that the existence of a completely phase separated PDMS soft phase in Elast‐Eon™ protects the remainder of the segments from oxidation. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
New method for routine production of L‐[methyl‐11C]methionine: in loop synthesis
Authors: Gómez Vanessa , Gispert Juan Domingo , Amador Víctor , Llop Jordi
Published: January 2008

A fast, clean and reproducible method for the manufacture of the radiotracer L‐[methyl‐11C]methionine is reported. The reaction at room temperature of the non‐radioactive precursor L‐homocysteine (1 mg solution in ethanol/water 50/50) with [11C]CH3I in an HPLC loop led to the formation of the desired radiotracer with a high radiochemical yield (38.4±4.1% end of synthesis) in a short production time (12 min). Radiochemical purity of the final radiotracer was 99.9±0.05%. Specific activities in the range 11–45 GBq/µmol were obtained. The presence of the undesired enantiomer (D‐[methyl‐11C]methionine) was not detected in any of the cases. Copyright © 2008 John Wiley & Sons, Ltd.
Histological analysis of achilles tendons in an overuse rat model
Authors: Glazebrook Mark A. , Wright James R. , Langman Maxine , Stanish William D. , Lee J. Michael
Published: January 2008

The purpose of this study was to design an animal model that induces histological changes in Achilles tendons consistent with those cited in the literature for human Achilles tendon disease. Sprague‐Dawley rats were subjected to 10° uphill treadmill running on a custom‐designed rodent treadmill and at a speed of 17 meters per minute for 1 h, five times per week, over a 12‐week treatment period. Subsequent histological analysis revealed alterations in the rat Achilles tendon that were generally consistent with those described in the literature for diseased human tendon tissues. These features include: decreased collagen fiber organization, more intense collagen staining, and increased cell nuclei numbers. Interestingly, though, immunohistochemical cell typing suggests that the observed increased cellularity does not include a significant inflammatory component but is secondary to increased numbers of endothelial cells (i.e., vascularization) and fibroblasts. These histological features likely represent a biological repair/remodeling response resulting from overuse running. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:840–846, 2008
Chemical characterization of polyol ester aviation lubricant residues
Authors: Bartl P. , Völkl C. , Kaiser M.
Published: January 2008

This study was conducted to evaluate the potential of pyrolysis gas chromatography/mass spectrometry in the electron impact and the chemical ionisation mode to characterize the chemical nature of solid deposits of polyol ester aviation lubricants generated in a laboratory test. Pyrolysis products can be unambiguously identified or plausibly derived using previous results on the structure of oligomeric aging products. Experience gained from model esters can easily transferred to fully formulated lubricants. The results are complemented by 13C‐NMR data and thermal analysis which elucidate the heterogeneity of the deposits. Copyright © 2008 John Wiley & Sons, Ltd.
Plant‐derived polyphenols attenuate lipopolysaccharide‐induced nitric oxide and tumour necrosis factor production in murine microglia and macrophages
Authors: Shanmugam Kirubakaran , Holmquist Lina , Steele Megan , Stuchbury Grant , Berbaum Katrin , Schulz Oliver , Benavente García Obdulio , Castillo Julián , Burnell Jim , Garcia Rivas Vernon , Dobson Geoff , Münch Gerald
Published: January 2008

Lipopolysaccharides released during bacterial infections induce the expression of pro‐inflammatory cytokines and lead to complications such as neuronal damage in the CNS and septic shock in the periphery. While the initial infection is treated by antibiotics, anti‐inflammatory agents would be advantageous add‐on medications. In order to identify such compounds, we have compared 29 commercially available polyphenol‐containing plant extracts and pure compounds for their ability to prevent LPS‐induced up‐regulation of NO production. Among the botanical extracts, bearberry and grape seed were the most active preparations, exhibiting IC50 values of around 20 μg/mL. Among the pure compounds, IC50 values for apigenin, diosmetin and silybin were 15, 19 and 12 μM, in N‐11 murine microglia, and 7, 16 and 25 μM, in RAW 264.7 murine macrophages, respectively. In addition, these flavonoids were also able to down‐regulate LPS‐induced tumour necrosis factor production. Structure‐activity relationships of the flavonoids demonstrated three distinct principles: (i) flavonoid‐aglycons are more potent than the corresponding glycosides, (ii) flavonoids with a 4′‐OH substitution in the B‐ring are more potent than those with a 3′‐OH‐4′‐methoxy substitution, (iii) flavonoids of the flavone type (with a C2=C3 double bond) are more potent than those of the flavanone type (with a at C2‐C3 single bond).
MRI in ocular drug delivery
Authors: Li S. Kevin , J. Lizak Martin , Jeong Eun‐Kee
Published: January 2008

Conventional pharmacokinetic methods for studying ocular drug delivery are invasive and cannot be conveniently applied to humans. The advancement of MRI technology has provided new opportunities in ocular drug‐delivery research. MRI provides a means to non‐invasively and continuously monitor ocular drug‐delivery systems with a contrast agent or compound labeled with a contrast agent. It is a useful technique in pharmacokinetic studies, evaluation of drug‐delivery methods, and drug‐delivery device testing. Although the current status of the technology presents some major challenges to pharmaceutical research using MRI, it has a lot of potential. In the past decade, MRI has been used to examine ocular drug delivery via the subconjunctival route, intravitreal injection, intrascleral injection to the suprachoroidal space, episcleral and intravitreal implants, periocular injections, and ocular iontophoresis. In this review, the advantages and limitations of MRI in the study of ocular drug delivery are discussed. Different MR contrast agents and MRI techniques for ocular drug‐delivery research are compared. Ocular drug‐delivery studies using MRI are reviewed. Copyright © 2008 John Wiley & Sons, Ltd.
An investigation of human brain tumour lipids by high‐resolution magic angle spinning 1H MRS and histological analysis
Authors: Opstad Kirstie S. , Bell B. Anthony , Griffiths John R. , Howe Franklyn A.
Published: January 2008

NMR‐visible lipid signals detected in vivo by 1H MRS are associated with tumour aggression and believed to arise from cytoplasmic lipid droplets. High‐resolution magic angle spinning (HRMAS) 1H MRS and Nile Red staining were performed on human brain tumour biopsy specimens to investigate how NMR‐visible lipid signals relate to viable cells and levels of necrosis across different grades of glioma. Presaturation spectra were acquired from 24 adult human astrocytoma biopsy samples of grades II (8), III (2) and IV (14) using HRMAS 1H MRS and quantified using LCModel to determine lipid concentrations. Each biopsy sample was then refrozen, cryostat sectioned, and stained with Nile Red, to determine the number of lipid droplets and droplet size distribution, and with Haematoxylin and Eosin, to determine cell density and percentage necrosis. A strong correlation (R = 0.92, P < 0.0001) was found between the number of Nile Red‐stained droplets and the ∼1.3 ppm lipid proton concentration by 1H MRS. Droplet sizes ranged from 1 to 10 µm in diameter, and the size distribution was constant independent of tumour grade. In the non‐necrotic biopsy samples, the number of lipid droplets correlated with cell density, whereas in the necrotic samples, there were greater numbers of droplets that showed a positive correlation with percentage necrosis. The correlation between 1H MRS lipid signals and number of Nile Red‐stained droplets, and the presence of lipid droplets in the non‐necrotic biopsy specimens provide good evidence that the in vivo NMR‐visible lipid signals are cytoplasmic in origin and that formation of lipid droplets precedes necrosis. Copyright © 2008 John Wiley & Sons, Ltd.
Preparation and characterization of thermally stable poly(amide‐urea)s functionalized with anthraquinone chromophore
Authors: Mehdipour‐Ataei Shahram , Bahri‐Laleh Naeemeh
Published: January 2008

Two new diamines containing bulky anthraquinone pendant units were prepared via reactions of 1‐ and 2‐aminoanthraquinone with 3,5‐dinitrobenzoylchloride and a subsequent reduction of their nitro groups. A novel series of highly organosoluble poly(amide‐urea)s were synthesized from the reactions of the prepared diamines with various commercially available diisocyanates via a step‐growth addition reaction process in N‐methyl‐2‐pyrrolidone (NMP). The effects of two factors (time and temperature) on the reaction were studied to optimize the conditions for the preparation of high molecular weight polymers. All poly(amide‐urea)s were characterized by Fourier Transform Infrared (FTIR) and 1H‐nuclear magnetic resonance (NMR) spectroscopies and elemental analysis. The resulting poly(amide‐urea)s had inherent viscosities in the range of 0.54–0.73 dl/g. They exhibited excellent solubility in polar solvents. The temperature for 10% weight loss of the polymers in air was all above 285°C, their residues were more than 36% at 700°C in air, and their Tg values were in the range of 148–190°C. According to the wide‐angle X‐ray diffraction (WAXD), the polymers were almost amorphous. The optical properties of poly(amide‐urea)s measured by ultraviolet–visible (UV–Vis) spectroscopy showed absorption maxima at 303–429 nm. Copyright © 2008 John Wiley & Sons, Ltd.
Subunit–subunit interactions in the human 26S proteasome
Authors: Chen Chuan , Huang Caoxin , Chen Shouhui , Liang Jie , Lin Wenbo , Ke Guifen , Zhang Hongxin , Wang Bing , Huang Jian , Han Zeguang , Ma Lixin , Huo Keke , Yang Xiaoming , Yang Pengyuan , He Fuchu , Tao Tao
Published: January 2008

Ubiquitin‐dependent proteolysis is mediated by the proteasome. To understand the structure and function of the human 26S proteasome, we cloned complete ORFs of 32 human proteasome subunits and conducted a yeast two‐hybrid analysis of their interactions with each other. We observed that there are 114 interacting‐pairs in the human 26S proteasome. About 10% (11/114) of these interacting‐pairs was confirmed by the GST‐pull down analysis. Among these observed interacting subunits, 58% (66/114) are novel and the rest 42% (48/114) has been reported previously in human or in other species. We observed new interactions between the 19S regulatory particle and the β‐rings of the 20S catalytic particle and therefore proposed a modified model of the 26S proteasome.
Natural orbital functional description of van der Waals interactions: A case study of the effect of the basis set for the helium dimer
Authors: Piris Mario , Lopez Xabier , Ugalde Jesus M.
Published: January 2008

We report on natural orbital functional calculations of the potential energy curve of the helium dimer. The performance of the recently proposed natural orbital functional (Piris et al. J Chem Phys 2007, 126, 214103) for the treatment of van der Waals interactions is assessed with respect to the increase of the number functions of the augmented correlation consistent polarized valence basis set series. Satisfactory converged towards the experimental equilibrium distance and binding energy is observed with the increase of the number of functions of the basis set. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
Water flow through nanopore
Authors: Di Leo Julio Marañón , Marañón Julio
Published: January 2008

A molecular dynamics simulation of water flow through a prismatic surface of van der Waals particles at 300 K is reported. The application of different pressure gradients to a water produces a large spectrum of average velocities from Poiseuille to turbulent flow. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
Laser ablation synthesis of phosphorus sulphides, selenides and ternary PpSqSer clusters from various precursors
Authors: Houška Jan , Alberti Milan , Havel Josef
Published: January 2008

Laser ablation (LA) synthesis with simultaneous time‐of‐flight mass spectrometric (TOF MS) analysis was used to examine the formation and composition of ternary PpSqSer clusters. Clusters formed by LA of various precursors are singular, binary and ternary. Formation of negative or positive singly charged Pp, Sq and Ser clusters, where P (p = 1–249), P (p = 1–191), S (q = 1–15), S (q = 1–12), Se (r = 1–8) and Se (r = 1–9), was identified. High numbers of binary PpSq, SqSer (35) or ternary PpSqSer (138) clusters were formed by LA synthesis from the various mixtures. Most of the ternary PpSqSer clusters were formed either from a mixture of P4S3 with selenium (grey) or from a mixture of SeS2 with red phosphorus. In total, 138 new ternary PpSqSer clusters were identified. The conditions for the formation of such possible prospective nano‐materials are given. Copyright © 2008 John Wiley & Sons, Ltd.
Vacuum: a void full of questions
Authors: Paparazzo Ernesto
Published: January 2008

This paper discusses views of vacuum proposed by Greek philosophers in the time span ranging from the 5th century B.C. to the 6th century A.D. The Eleatic Melissus (5th century B.C.) denied the existence of vacuum. The Early Atomist Leucippus, his followers and Epicurus asserted that the full (matter) and the empty (vacuum) are the irreducible elements of the universe. While the Early Atomists emphasized the metaphysical status of vacuum, which they defined as that which is ‘the nothing’ or ‘the non‐existent’, Epicurus was mostly concerned with stating that it was a sort of fluid medium with an ‘intangible nature’, which allowed material objects to move within it by yielding to them. Plato held that a vacuum does not exist, apart from small interstices in matter. Aristotle rejected the existence of both vacuum and the motion of a body in it. Also, the Stoics denied its existence, except outside the cosmos. These philosophical views are compared with the notion of a vacuum relevant to a typical surface science experiment. Copyright © 2008 John Wiley & Sons, Ltd.
Spectroscopic investigations of the role of Ge in modifying the Si to SiC conversion process
Authors: Pezoldt Jörg , Nader Richard , Zgheib Charbel , Ecke Gernot , Pieterwas Ralph , Stauden Thomas , Wöhner Thomas , Masri Pierre
Published: January 2008

The influence of Ge on the conversion process of Si to SiC was studied by depositing Ge and C on Si(111) followed by a stepwise annealing procedure. After the annealing step, the carbon deposited on the surface was completely converted into SiC. In the case of Ge predeposition, the SiC amount detected by XPS, AES and ellipsometry was lower compared to the reference sample in which no Ge was predeposited on the Si(111) surface. Therefore, Ge lowers the probability of SiC formation in the early stages. During the conversion process, Ge diffuses into the Si substrate and is mainly located near the SiCSi interface with a concentration of around 2.5–3%. As a result of a complex alloying process promoted by interdiffusion of C and Ge as well as SiC nucleation, a thin 3C‐SiC layer is formed on top of a Si1−xGex buffer layer. Copyright © 2008 John Wiley & Sons, Ltd.
Characterization of surface oxide layers formed on FeAl alloys by annealing under different atmospheres
Authors: Suzuki Shigeru , Yamamoto Takamichi , Shinoda Kozo , Sato Shigeo
Published: January 2008

XPS and SIMS were used for characterizing the surface oxide layers formed on FeAl alloys during annealing under atmospheres with different partial pressures of oxygen, which were controlled by H2O/H2 ratios in the gas. The XPS results showed that an aluminum oxide (Al2O3) layer was formed on the surfaces of samples annealed at a high temperature under a low partial pressure of oxygen, while such a layer was not formed on the surfaces of samples annealed under a high partial pressure of oxygen. SIMS depth profiles showed that the surfaces of samples annealed at high temperatures under a low partial pressure of oxygen were covered with a thin Al2O3 layer of approximately 50 nm thickness. It was also shown that oxygen penetrated the samples annealed under a high partial pressure of oxygen, and the depth profile of oxygen was correlated with that of aluminum. This indicates that internal oxidation of aluminum occurs in the samples annealed under a high partial pressure of oxygen. Grazing‐incidence X‐ray diffraction (GIXD) was also employed for analyzing the structure of the Al2O3 layer formed on the surface of samples annealed under a low partial pressure of oxygen. Copyright © 2008 John Wiley & Sons, Ltd.
Monte Carlo computations of the electron backscattering coefficient for bulk targets and surface thin films
Authors: Dapor Maurizio
Published: January 2008

Monte Carlo computations of the electron backscattering coefficient as a function of the primary energy in the range 500 eV–5 keV for several bulk targets (Al, Si, Cr, Ni, Cu, Ge, Au) are provided. Monte Carlo simulated backscattering coefficients from several surface thin layers are also provided as a function of the electron primary energy and film thicknesses. While the elastic scattering cross‐sections have been calculated by the relativistic partial wave expansion method, the stopping power data utilized by the Monte Carlo code are taken from the literature. Copyright © 2008 John Wiley & Sons, Ltd.
Aussteifung von Gebäudehüllen durch randverklebte Glasscheiben
Authors: Wellershoff Frank
Published: January 2008

Das Streben nach immer transparenteren Gebäudehüllen mit immer filigraneren Tragstrukturen weckt den Wunsch, die Verglasung als aussteifendes Element zu nutzen und Kräfte in der Scheibenebene abzutragen. Besonders geeignet erscheinen hierfür Stabgitterschalen mit viereckigen Maschen. Bei diesem Tragwerkstyp werden ebene oder gekrümmte Flächen durch ein Netz aus Stäben gebildet. Zur Minimierung der Stabquerschnitte und der Montagekosten können die Stäbe in der Schalenebene gelenkig aneinander geschraubt werden. Nach dem heutigen Stand der Technik wird dieser Stabgitterschalentyp durch diagonale Zugstäbe oder vorgespannte Seile in der Schalenebene stabilisiert. Diese Diagonalelemente könnten entfallen, wenn die Aussteifung von der Verglasung übernommen würde.

Bei dem hier betrachteten System werden die Verglasungselemente als Schubfelder aktiviert. Hierzu werden die Glasscheiben umlaufend mit den viereckigen Stabgittermaschen verklebt. Für dieses System wurden Details konzipiert und das Tragverhalten der Anschlüsse sowie der Glasscheiben zwischen den Gittermaschen und der Verglasung untersucht und Bemessungsmodelle entwickelt. Diese berücksichtigen die Verbundwirkung von Verbundglasscheiben und die Interaktion von Aussteifungskräften in der Scheibenebene mit den Plattenbelastungen senkrecht zur Scheibenebene.
Wirtschaftliche Bemessung von Druckstäben aus gewalzten I‐Profilen mit dem Kappa‐Verfahren
Authors: Kindmann Rolf , Wolf Christian
Published: January 2008

Im Vordergrund des Aufsatzes steht die Beurteilung der κ‐Werte für Druckstäbe aus gewalzten I‐Profilen. Anhand rechnerisch ermittelter κ‐Werte werden die Genauigkeit überprüft und vorhandene Reserven aufgezeigt. Zur Ausnutzung dieser Reserven wird neben der Angabe der genauen κ‐Werte eine neue Knickspannungslinie “ab” vorgeschlagen. Sie ermöglicht für typische Stützenprofile mit h/b ≤ 1,2, also für baupraktisch besonders interessante Anwendungsfälle, eine wirtschaftlichere Bemessung als bisher.
Berechnung von Flüssigkeitsbehältern unter Erdbebeneinwirkung
Authors: Habenberger Jörg
Published: January 2008

Zur Berechnung der Interaktionsschwingung von Flüssigkeit und zylindrischer Behälterwand wird im Anhang A des Eurocode 8, Teil 4 ein Iterationsverfahren vorgeschlagen, das den Flüssigkeitsdruck als erhöhte effektive Dichte der “trockenen” Behälterwand berücksichtigt. Um dabei auftretende Singularitäten am Behälterfuß zu vermeiden, sind zusätzliche Maßnahmen erforderlich. Im vorliegenden Beitrag wird ein alternativer Ansatz vorgeschlagen, der diese Singularitäten umgeht und einfacher in der Anwendung ist. Die Methode wird auf eine Serie von Behältern angewendet und mit Ergebnissen anderer Untersuchungen verglichen.
Some thermal properties of methyl malvalate, methyl sterculate, and their dihydro derivatives
Authors: White J. L. , Zarins A. , Feuge R. O.
Published: January 2008

Abstract and Summary

Methyl esters of cyclopropene acids, malvalic and sterculic, and their dihydro derivatives, were highly purified and examined for melting points, poly‐morphic behavior, heats of fusion, and dilatometric behavior. Results revealed that the quickly chilled forms of the unsaturated methyl esters underwent a rapid monotropic transformation. The dihydro derivatives exhibited no detectable polymorphism. The melting dilation for methyl malvalate was signifi‐cantly below the previously reported dilations of other fatty acid methyl esters.
Surface active properties of combinations of soap and lime soap dispersing agents
Authors: Weil J. K. , Linfield W. M.
Published: January 2008

Abstract and Summary

Surface tension versus log concentration curves were obtained for combinations of a variety of lime soap dispersing agents (LSDA) with sodium oleate. Salient features of the curves for these mixtures were: (a) criticial micelle concentration (CMC) close to that for LSDA alone; (b) absence of a surface tension minimum or substantial reduction in the minimum, which was often found with LSDA alone; (c) surface tension values above the CMC very close to those found for soap alone above its CMC; and (d) slope below the CMC greater than that for soap alone, more like that for soap with alkali added or lime soap dispersing agent alone. Higher CMC values were confirmed by dye solubilization measurements. The surface tension curves provided further evidence for the mixed micellar nature of soap‐LSDA mixtures and suggested that the addition of LSDA to soap increased the surface concentration of surfactant.
Ion exchange resins and ethyleneimine polymer as antioxidants II: Autoxidation products
Authors: Ikeda Nobuo , Fukuzumi Kazuo
Published: January 2008

Abstract and Summary

The antioxidant effects of ion exchange resins and ethyleneimine polymer on the autoxidation products of methyl linoleate in a heterogeneous reaction system are discussed. Results from analyses of the various autoxidation products from linoleate samples with and without the antioxidants showed that the addi‐tion of the antioxidants did not change the original autoxidation mechanism of methyl linoleate. How‐ever, the antioxidants did retard the autoxidation in response to their antioxidant activity and, compared with a linoleate control, changed the yields of some autoxidized products such as an increased amount of conjugated diene hydroperoxides in linoleate samples with added ion exchange resins.
Analytical13C NMR: A rapid, nondestructive method for determining the cis,trans composition of catalytically treated unsaturated lipid mixtures
Authors: Pfeffer Philip E. , Luddy Francis E. , Unruh Joseph , Shoolery James N.
Published: January 2008

Abstract and Summary

High resolution natural abundance 13C Fourier transform nuclear magnetic resonance (NMR) has been found to be an effective tool for the rapid and direct determination of the cis/trans composition in partially hydrogenated and isomerized unsaturated lipids. With the eis and trans allylic carbon resonances as representative probes for double bond stereo‐chemistry. Evaluation of the cis/trans composition of complex, positionally isomerized mixtures can be made without the necessity of carrying out detailed analyses of multishift olefinic carbon resonances. Migration of double bonds in monoenes and polyenes and formation of conjugated unsaturation in cata‐lytically treated fats are discussed and assessed as possible sources of error in the evaluation of cis/trans isomer ratios. Carbon spin lattice relaxation times T1 were measured for both cis and trans allylic reson‐ances in isomeric mixtures of varying composition to assure quantitative intensity relationships. 13C NMR compositional analysis of complex mixtures is demonstrated.
Long‐term Outcome of Reoperations for Medullary Thyroid Carcinoma
Authors: Fialkowski Elizabeth , DeBenedetti Mary , Moley Jeffrey
Published: January 2008

Background

Most patients with medullary thyroid carcinoma (MTC) have persistent disease after primary surgery, as evidenced by calcitonin elevation. Previous reports showed that reoperation on selected patients yields immediate calcitonin normalization in one‐third of patients. Long‐term follow‐up data are needed to assess the outcome in such patients. This report aims to provide 8– to 10–year follow‐up on reoperations for persistent or recurrent MTC.

Methods

An Internal Review Board (IRB) approved database on patients treated for MTC has been prospectively maintained. This database was reviewed to report follow‐up data on calcitonin levels and survival.

Results

Between 1992 and 2006, 148 patients underwent reoperations for recurrent or persistent MTC (55 patients had 59 reoperations for palliation, and 93 patients had 105 reoperations for cure). Of the 93 patients operated on for cure (44 with hereditary MTC, 49 with the sporadic form), 8–10‐year follow‐up data were available on 56. Four patients died of disease (4.3% of 93). Two died of unrelated causes, and were excluded from calcitonin outcome analysis. Fourteen patients of 54 (26.0%) have unstimulated calcitonin levels of < 10 pg/ml at 8–10 years. Eleven additional patients (20.4%) have levels < 100 pg/ml. None of these 25 patients (46.4%) have radiologic recurrence.

Conclusions

Previous reports demonstrated the low morbidity of reoperation for MTC in experienced hands, and success was determined by lowering of calcitonin levels. Follow‐up data demonstrate that at least one third of such patients have long‐term eradication of their disease following reoperation, as evidenced by biochemical and imaging studies.