bluuebunny/crossref_metadata_2025 huggingface dataset:
Processing of PLP in a model of Pelizaeus‐Merzbacher disease/SPG2 due to the rumpshaker mutation
Authors: McLaughlin Mark , Barrie Jennifer A. , Karim Saadia , Montague Paul , Edgar Julia M. , Kirkham Douglas , Thomson Christine E. , Griffiths Ian R
Published: February 2006

The rumpshaker mutation of the X‐linked myelin proteolipid protein (PLP1) gene causes spastic paraplegia type 2 or a mild form of Pelizaeus‐Merzbacher disease in man. The identical mutation occurs spontaneously in mice. Both human and murine diseases are associated with dysmyelination. Using the mouse model, we show that the low steady state levels of PLP result from accelerated proteasomal degradation rather than decreased synthesis. The T1/2 for degradation of rumpshaker PLP is 11 h compared with 23 h for wild type. A minority of newly synthesized PLP is incorporated into myelin in the correct orientation but at a reduced rate compared with wild type. However, inhibition of proteasomal degradation does not increase the level of PLP incorporated into myelin. As Plp null mice do not have a similar myelin deficiency, it is unlikely that the reduced PLP levels are the main cause of the dysmyelination. Rumpshaker oligodendrocytes also have a reduced level of other myelin proteins, such as MBP, although the mechanisms are not yet defined but are likely to operate at a translational or post‐translational level. © 2006 Wiley‐Liss, Inc.
The relevance of a geriatric sub‐classification of personality disorders in the DSM‐V
Authors: van Alphen S. P. J. , Engelen G. J. J. A. , Kuin Y. , Derksen J. J. L.
Published: February 2006

Little is known about the course of personality disorders across the life span. A major problem is that the current DSM nosology for personality disorders does not account for age‐associated changes in behaviour and interpersonal functioning. This editorial will discuss the main diagnostic bottlenecks when applying the current DSM‐IV‐TR Axis II criteria to older adults. Subsequently, suggestions will be given for future research and the development of a geriatric sub‐classification. Copyright © 2006 John Wiley & Sons, Ltd.
Hippocampal neurogenesis: Opposing effects of stress and antidepressant treatment
Authors: Warner‐Schmidt Jennifer L. , Duman Ronald S.
Published: February 2006

The hippocampus is one of several limbic brain structures implicated in the pathophysiology and treatment of mood disorders. Preclinical and clinical studies demonstrate that stress and depression lead to reductions of the total volume of this structure and atrophy and loss of neurons in the adult hippocampus. One of the cellular mechanisms that could account for alterations of hippocampal structure as well as function is the regulation of adult neurogenesis. Stress exerts a profound effect on neurogenesis, leading to a rapid and prolonged decrease in the rate of cell proliferation in the adult hippocampus. In contrast, chronic antidepressant treatment up‐regulates hippocampal neurogenesis, and could thereby block or reverse the atrophy and damage caused by stress. Recent studies also demonstrate that neurogenesis is required for the actions of antidepressants in behavioral models of depression. This review discusses the literature that has lead to a neurogenic hypothesis of depression and antidepressant action, as well as the molecular and cellular mechanisms that underlie the regulation of adult neurogenesis by stress and antidepressant treatment. © 2006 Wiley‐Liss, Inc.
Changes in late‐winter snowpack depth, water equivalent, and density in Maine, 1926–2004
Authors: Hodgkins Glenn A. , Dudley Robert W.
Published: February 2006

Twenty‐three snow‐course sites in and near Maine, USA, with records spanning at least 50 years through to 2004 were tested for changes over time in snowpack depth, water equivalent, and density in March and April. Of the 23 sites, 18 had a significant decrease (Mann‐Kendall test, p < 0·1) in snowpack depth or a significant increase in snowpack density over time. Data from four sites in the mountains of western Maine–northern New Hampshire with mostly complete records from 1926 to 2004 indicate that average snowpack depths have decreased by about 16% and densities have increased by about 11%. Average snowpack depths and water equivalents in western Maine–northern New Hampshire peaked in the 1950s and 1960s, and densities peaked in the most recent decade. Previous studies in western North America also found a water‐equivalent peak in the third quarter of the 20th century. Published in 2006 by John Wiley & Sons, Ltd.
Microbial habitat dynamics and ablation control on the Ward Hunt Ice Shelf
Authors: Mueller Derek R. , Vincent Warwick F.
Published: February 2006

The Ward Hunt Ice Shelf (83°02′N, 74°00′W) is an ∼40 m thick ice feature that occupies a large embayment along Canada's northernmost coast. Sediments cover 10% of its surface and provide a habitat for diverse microbial communities. These assemblages form an organo‐sedimentary matrix (microbial mat) composed of cold‐tolerant cyanobacteria and several other types of organisms. We investigated the environmental properties (temperature, irradiance, conductivity and nutrient concentration) of the microbial mat habitat and the effect of the microbial mats on the surface topography of the ice shelf. The low albedo of microbial mats relative to the surrounding snow and ice encouraged meltwater production, thereby extending the growth season to 61 days despite only 52 days with mean temperatures above 0 °C. We found large excursions in salinity near the microbial mat during freeze‐up and melt, and 54% of all ponds sampled had conductivity profiles indicating stratification. Nutrient concentrations within the microbial mats were up to two orders of magnitude higher than those found in the water column, which underscores the differences between the microbial mat microenvironment and the overall bulk properties of the cryo‐ecosystem. The average ice surface ablation in the microbial mat‐rich study site was 1·22 m year−1, two times higher than values measured in areas of the ice shelf where mats were less prevalent. We demonstrate with topographic surveys that the microbial mats promote differential ablation and conclude that the cohesive microbial aggregates trap and stabilize sediment, reduce albedo, and thereby influence the surface morphology of the ice shelf. Copyright © 2006 John Wiley & Sons, Ltd.
Boundary‐layer growth and advection of heat over snow and soil patches: modelling and parameterization
Authors: Essery Richard , Granger Raoul , Pomeroy John
Published: February 2006

Melting snow is generally patchy; upward sensible heat fluxes from patches of snow‐free ground warm the air and contribute energy for snowmelt. A simple model is presented for advection of heat over partial snow covers and compared with measurements of temperature profiles over snow and snow‐free ground. Approximations for flux and temperature profiles in the internal boundary layers over snow patches are used to develop parameterizations for local and average surface fluxes into the snow. In comparison with results from the advection model for regular patterns of alternating snow patches and snow‐free ground, a tile model is found to give a good parameterization for average heat fluxes over the whole surface, but it does not match the local fluxes into snow and snow‐free ground separately. An extended tile model that gives better results is developed from the flux profile parameterization. For complex snow‐cover patterns with a fractal distribution of patch sizes, average fluxes are found to be close to those obtained for a regular pattern with an effective patch size linearly related to the average patch size of the complex pattern. Copyright © 2006 Environment Canada. Published by John Wiley & Sons, Ltd.
Relationship between atmospheric circulation and snowpack in the western USA
Authors: Jin Jiming , Miller Norman L. , Sorooshian Soroosh , Gao Xiaogang
Published: February 2006

Snow anomalies in the western USA have a significant impact on water availability, and hence have been widely investigated by many researchers. This study focuses on how anomalous atmospheric circulation affects snowpack accumulation in the western USA. Our results indicate that the mid‐latitude atmospheric circulation anomalies induced by the El Niño–Southern Oscillation (ENSO) tend to drive winter precipitation shifts, leading to an anomalous snowpack distribution in the western USA. The warm phase of ENSO produces increased snowpack in the Southwest, whereas the cold phase generates increased snowpack in the Northwest. The results also indicate that temperature has a secondary impact on the anomalous snowpack distribution during ENSO episodes. Additionally, the atmospheric internal variability‐related Pacific–North American (PNA) pattern is found to affect snow anomalies strongly in the western USA independent from ENSO. The positive phase of the PNA pattern produces colder temperature and stronger precipitation due to the lower pressure in the region, leading to an above‐average snowpack. Conversely, the negative phase of the PNA pattern generates warmer temperature and weaker precipitation resulting from the higher pressure, producing below‐average snowpack in the western USA. The significant findings that result from this study strengthen our understanding of climate and water supply variability in the western USA. Copyright © 2006 John Wiley & Sons, Ltd.
Relationship between passive microwave‐derived snowmelt and surface‐measured discharge, Wheaton River, Yukon Territory, Canada
Authors: Ramage J. M. , McKenney R. A. , Thorson B. , Maltais P. , Kopczynski S. E.
Published: February 2006

Snow volume and melt timing are major factors influencing the water cycle at northern high altitudes and latitudes, yet both are hard to quantify or monitor in remote mountainous regions. Twice‐daily special sensor microwave imager (SSM/I) passive microwave observations of seasonal snow melt onset in the Wheaton River basin, Yukon Territory, Canada (∼60 ° 08′05″N, ∼134 ° 53′45″W), are used to test the idea that melt onset date and duration of snowpack melt–refreeze fluctuations control the timing of the early hydrograph peaks with predictable lags. This work uses the SSM/I satellite data from 1988 to 2002 to evaluate the chronology of melt and runoff patterns in the upper Yukon River basin. The Wheaton River is a small (875 km2) tributary to the Yukon, and is a subarctic, partly glacierized heterogeneous basin with near‐continuous hydrographic records dating back to 1966. SSM/I pixels are sensitive to melt onset due to the strong increase in snow emissivity, and have a robust signal, in spite of coarse (>25 × 25 km2) pixel resolution and varied terrain. Results show that Wheaton River peak flows closely follow the end of large daily variations in brightness temperature of pixels covering the Wheaton River, but the magnitude of flow is highly variable, as might be expected from interannual snow mass variability. Spring rise in the hydrograph follows the end of high diurnal brightness temperature (Tb) amplitude variations (DAV) by 0 to 5 days approximately 90% of the time for this basin. Subsequent work will compare these findings for a larger (7250 km2), unglacierized tributary, the Ross River, which is farther northeast (∼61 ° 59″40″N, ∼132 ° 22″40″W) in the Yukon Territory. These techniques will also be used to try to determine the improvement in melt detection and runoff prediction from the higher resolution (∼15 × 15 km2) advanced microwave scanning radiometer for EOS (AMSR‐E) sensor. Copyright © 2006 John Wiley & Sons, Ltd.
The relationship between microsatellite instability and PTEN gene mutations in endometrial cancer
Authors: Bilbao Cristina , Rodríguez Germán , Ramírez Raquel , Falcón Orlando , León Laureano , Chirino Ricardo , Rivero Juan F. , Falcón Orlando , Díaz‐Chico B. Nicolás , Díaz‐Chico Juan C. , Perucho Manuel
Published: February 2006

Microsatellite instability (MSI) and mutations in the PTEN gene are among the molecular alterations involved in endometrial carcinogenesis. There is conflicting information regarding to their role in this type of tumor. For this reason, we have studied both molecular lesions in a large population‐based series of 205 patients with sporadic endometrial cancer. MSI was found in 41 (20.0%) of the tumors and PTEN mutations were found in 74 (36.1%). There were differences in genotype between tumors with and without MSI. Tumors with MSI showed both a higher frequency of PTEN mutations (58.5% vs. 30.4%) (p = 0.002, Fisher's exact test) and a higher number of insertions or deletions (I/D) of one nucleotide within the mononucleotide tracts of the PTEN gene (45.8% vs. 11.4% out of all I/D, p = 0.005). Conversely, G:C to A:T transitions in CpG dinucleotides were found mostly in microsatellite stable tumors (57.7% vs. 18.2% out of all single‐base substitutions, p = 0.037). Overall, 67.6% of tumors with mutated PTEN exhibited multiple mutations or allelic imbalance (AI). Multiple PTEN mutations in the same tumor were more frequent in tumors with MSI (60% vs. 25.7%); by contrast the presence of AI accompanying PTEN mutation was higher in microsatellite stable tumors (74.3% vs. 40%) (p = 0.028). In addition, patients with both genetic alterations were diagnosed at more advanced stage of progression (54.2% for MSI vs. 20.0% for MSS, p = 0.006), and exhibited a worse prognosis (hazard ratio [95% confidence interval]: 3.0 [1.1–13.1], p = 0.034, log‐rank test) than patients with only the PTEN gene mutated. Our data suggest that the DNA mismatch repair system status influences: (i) both the frequency and the mutational spectrum of PTEN; (ii) the nature of one of the hits that inactivate this tumor‐suppressor gene; and (iii) the clinical condition and behavior of the patients. © 2006 Wiley‐Liss, Inc.
Genetic variation in the COX‐2 gene and the association with prostate cancer risk
Authors: Shahedi K. , Lindström S. , Zheng S.L. , Wiklund F. , Adolfsson J. , Sun J. , Augustsson‐Bälter K. , Chang B.‐L. , Adami H.‐O. , Liu W. , Grönberg H. , Xu J.
Published: February 2006

COX‐2 is a key enzyme in the conversion of arachidonic acid to prostaglandins. The prostaglandins produced by COX‐2 are involved in inflammation and pain response in different tissues in the body. Accumulating evidence from epidemiologic studies, chemical carcinogen‐induced rodent models and clinical trials indicate that COX‐2 plays a role in human carcinogenesis and is overexpressed in prostate cancer tissue. We examined whether sequence variants in the COX‐2 gene are associated with prostate cancer risk. We analyzed a large population‐based case–control study, cancer prostate in Sweden (CAPS) consisting of 1,378 cases and 782 controls. We evaluated 16 single nucleotide polymorphisms (SNPs) spanning the entire COX‐2 gene in 94 subjects of the control group. Five SNPs had a minor allele frequency of more than 5% in our study population and these were genotyped in all case patients and control subjects and gene‐specific haplotypes were constructed. A statistically significant difference in allele frequency between cases and controls was observed for 2 of the SNPs (+3100 T/G and +8365 C/T), with an odds ratio of 0.78 (95% CI = 0.64–0.96) and 0.65 (95% CI = 0.45–0.94) respectively. In the haplotype analysis, 1 haplotype carrying the variant allele from both +3100 T/G and +8365 C/T, with a population frequency of 3%, was also significantly associated with decreased risk of prostate cancer (p= 0.036, global simulatedp‐value = 0.046). This study supports the hypothesis that inflammation is involved in prostate carcinogenesis and that sequence variation within the COX‐2 gene influence the risk of prostate cancer. © 2006 Wiley‐Liss, Inc.
p53 mutation spectra for squamous cell carcinomas at different levels of human bronchial branches
Authors: Shimmyo Takuo , Hashimoto Takehisa , Kobayashi Yasuhito , Miyagi Youhei , Ishikawa Yuichi , Nakagawa Ken , Osada Hiroaki , Tsuchiya Eiju
Published: February 2006

The question of whether squamous cell carcinomas (SCCs) arising in different sites of lung are caused by different etiological factors is of obvious importance for prevention, early detection and effective treatment. We here subclassified a large series of resected SCCs (74 cases) into 3 tumor‐sites, central (main to segmental bronchi), intermediate (subsegmental to sub‐subsegmental) and peripheral (distal to sub‐subsegmental bronchi), and examined relationships with p53 mutational spectra and smoking history to provide clues to etiological factors. The rate for G→A transitions at CpG sites considered to be caused by endogenous mechanism was higher in central (40%) than in intermediate (0%) and peripheral (14%) lesions, in spite of highest percentage of heavy smokers. In contrast, G→T transversions associated with tobacco smoke carcinogens were most frequent (50%) in the intermediate location, although proportions of heavy smoker's ratio were the same among the locations when confined to p53 mutation cases. In the periphery, other mutations were highest (67%) compared with 33 and 50% in the central and intermediate regions, respectively. Thus, different etiological factors may be playing causal roles in the development of SCCs in different locations of bronchial tree. Furthermore, the results suggest that more extensive study of the influence of tobacco smoke carcinogens on endogenous mechanisms is warranted. © 2006 Wiley‐Liss, Inc.
In vivo biostability of polysiloxane polyether polyurethanes: Resistance to biologic oxidation and stress cracking
Authors: Ward Robert , Anderson James , McVenes Rick , Stokes Ken
Published: February 2006

Polyether polyurethanes are extremely interesting for use in implantable devices. They are, however, susceptible to autoxidative degradation and stress cracking. One approach to improving biostability is to replace some of the polyether with polysiloxane. Shore 80A polyether polyurethanes with 20% (PS‐20) and 35% (PS‐35) polysiloxane were strained to 400% elongation and implanted in rabbits. Twelve weeks implant showed that both were significantly more biostable than their polysiloxane‐free controls. After 18 months implant, PS‐20 developed some localized tensile fractures. PS‐35 showed no sign of visual damage. Infrared surface analysis does not allow direct evaluation of autoxidation because the SiOSi stretch peaks mask the polyether bands. Secondary indicators suggest possible very slight autoxidation of both PS‐20 and PS‐35 surfaces, but not enough to develop cracks. The polysiloxane‐free controls did show substantial infrared evidence of autoxidation. Molecular weights of long‐term PS‐20 and PS‐35 explants were negligibly lower. In comparison, the polysiloxane‐free control suffered 35% molecular weight loss. Positive and negative controls performed as expected. PS‐20 is recommended for devices that do not sustain high fixed loads. PS‐35 is dramatically more biostable than its unmodified polyether analogues and is recommended for use in chronically implantable devices. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Bioactive glass/polymer composite materials with mechanical properties matching those of cortical bone
Authors: Koleganova Veronika A. , Bernier Suzanne M. , Dixon S. Jeffrey , Rizkalla Amin S.
Published: February 2006

Stress shielding resulting from mismatch in dynamic mechanical properties contributes to the reduced stability of osseous implants. Our objective was to develop biocompatible composites having mechanical properties similar to those of cortical bone. Polymers of urethane dimethacrylate (UDMA) and 2‐hydroxyethyl methacrylate (HEMA, 0–20%) and composites containing bioactive glass particles (70% SiO2, 25% CaO, and 5% P2O5), with or without silane treatment were prepared. Young's moduli of composites containing silane‐treated glass (16 GPa) were significantly greater than those of composites containing untreated glass (12–13 GPa) or of unfilled polymers (5–6 GPa). Bioactive glass reduced water sorption by the composites and incorporation of silane‐treated glass prevented HEMA‐induced increases in water sorption. Osteoblast‐like cells attached equally well to UDMA polymer and composite containing silane‐treated bioactive glass. Thus, silane treatment improved the mechanical properties of bioactive glass composites without compromising biocompatibility. This material has a Young's modulus comparable to that of cortical bone. Therefore, silane‐treated bioactive glass composites, when used as implant or cement materials, would reduce stress shielding and improve implant stability. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Synthetic biodegradable microparticles for articular cartilage tissue engineering
Authors: Thissen H. , Chang K.‐Y. , Tebb T. A. , Tsai W.‐B. , Glattauer V. , Ramshaw J. A. M. , Werkmeister J. A.
Published: February 2006

Articular cartilage tissue engineering procedures require the transplantation of chondrocytes that have been expanded in vitro. The expansion is carried out for a considerable time and can lead to a modulation of cell phenotype. However, microcarrier cultures have been shown to allow cell expansion while maintaining the phenotype. Here, we have used the biodegradable polyester poly(lactide‐co‐glycolide) (PLGA) in the form of microspheres and irregular shaped microparticles with a diameter between 47 and 210 μm. Surface modification of particles was carried out by ammonia plasma treatment and subsequent adsorption of collagen. Alternatively, particles were modified by partial hydrolysis and subsequent immobilization of an amine‐terminated dendrimer. Each surface modification step was characterized by X‐ray photoelectron spectroscopy. The effectiveness of the surface modification procedures was demonstrated by in vitro cell culture experiments using sheep articular cartilage chondrocytes. A significant influence of both the particle shape and the surface chemistry on the proliferation rate was observed while the phenotype was maintained independent of the surface chemistry or particle shape. Chondrocytes cultured on PLGA microspheres were further assessed for cartilage tissue formation in collagen type I gels in nude mice. The tissue that were formed showed the appearance of a hyaline‐like cartilage and the presence of the microspheres substantially reduced the degree of collagen gel contraction over 1–2 months. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Osteoblast response to plasma‐spray porous Ti6Al4V coating on substrates of identical alloy
Authors: Saldaña L. , González‐Carrasco J.L. , Rodríguez M. , Munuera L. , Vilaboa N.
Published: February 2006

We have evaluated the in‐vitro biocompatibility of Ti6Al4V alloy coated by plasma spraying with an identical alloy. These surfaces are widely used in cementless prosthetic components, although osteoblasts behavior on this treated alloy has not been evaluated to date. Cross sectional examination revealed a thick and rough coating of identical composition without sign of delamination. Within the coating, small discontinuities and nonconnected pores were observed. Osteoblast response was evaluated by assessing cell adhesion, proliferation, and differentiation of primary cultures of human osteoblastic cells. Compared to the polished alloy, osteoblast adhesion measured as cell attachment and actin network reorganization was delayed on the plasma‐sprayed surface. Cell proliferation and viability were also impaired on the rough surface. Several informative markers of osteoblastic differentiation such as procollagen I peptide, alkaline phosphatase, osteocalcin, osteoprotegerin, and mineralized nodule formation were evaluated and indicated that the plasma‐sprayed alloy favored a more differentiated phenotype than polished alloy. Taken together, our in vitro results indicate that successful osseointegration of plasma spraying of Ti6Al4V with an identical alloy is mediated by modulation of osteoblastic differentiation and mineralization. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
In vitro and in vivo release of gentamicin from biodegradable discs
Authors: Naraharisetti Pavan Kumar , Guan Lee Herman Chian , Fu Yin‐Chih , Lee Duu‐Jong , Wang Chi‐Hwa
Published: February 2006

Osteomyelitis is an infection of the bone and successful treatment involves the removal of the affected bone and the tissue by a surgical procedure following prolonged systemic and local antibiotic therapy for 4 to 6 weeks. The current local treatment is done by poly methyl methacrylate (PMMA) beads loaded with gentamicin and PMMA, being nondegradable, is to be removed by a second surgical procedure. The current study aims to develop a biodegradable composition that gives sustained release and hence reducing the need for a second surgery. Gentamicin‐loaded discs were produced by compressing microparticle–gentamicin mixture obtained by spray drying a mixture of gentamicin in a solution of a biodegradable polymer. Different copolymers of poly (DL‐lactic‐co‐glycolic acid) (PLGA) were used to study the effect of copolymer ratio and the hydrophilic–hydrophobic nature of the polymer. Theoretical drug loading up to 25% were studied and it was observed that 10% drug loading was optimum for gentamicin to be used as solid in spray drying. The results showed that about 60% of the drug is released in about 5 to 6 days and the remaining drug is released in about 30 days in total. An in vivo study was carried on rabbit femur and the local area and systemic concentration of gentamicin was monitored. It was observed that the local area concentration of gentamicin was above minimum inhibitory concentration for more than 20 days and this was also validated by computer simulations. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Functional properties and performance of new and reprocessed coronary angioplasty balloon catheters
Authors: Fedel Mariangela , Tessarolo Francesco , Ferrari Paolo , Lösche Christian , Ghassemieh Nikou , Guarrera Giovanni Maria , Nollo Giandomenico
Published: February 2006

The need of health costs control has prompted the reuse of devices originally manufactured for single use only. To assess reprocessing feasibility of disposable medical devices, hygienic, technical, and functional aspects must be taken into account in addition to economical, ethical, and legal implications. This study aims to characterize coronary angioplasty catheters and to evaluate performance changes induced by reprocessing. Multiple analysis including crossing profile, slipperiness, compliance, mechanical, and burst pressure tests were performed at different steps of the protocol on 25 catheters reprocessed up to two times. The results highlighted that both use and reprocessing can affect the features of angioplasty catheters. Mechanical stress caused by clinical inflation and thermal–chemical stress undergone by polymers during cleaning and sterilization procedures caused partial modifications of material properties, inducing an overall shrinking effect on balloons. Compliance tests reported a maximum variation of 6.2% from nominal values, showing the conformity of reprocessed devices with manufacturers' original specifications (±10%). The burst pressure of reprocessed devices was 80% higher than the rated burst pressure certified by manufacturers, thus reducing concerns of breakage during reuse. A strict dependence on device model in the behavior of catheters was found, especially for balloons crossing profile and slipperiness. Main changes occurred after the first reprocessing cycle, while a second cleaning and sterilization did not introduce further significant alterations. On the whole, the magnitude of modifications introduced up to two reprocessing cycles did not compromise catheters performance. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Biodegradable and complexed microspheres used for sustained delivery and activity protection of SOD
Authors: Wang Ye , Gao Jian‐Qing , Zheng Cai‐Hong , Xu Dong‐Hang , Liang Wen‐Quan
Published: February 2006

To develop a new protein delivery system for superoxide dismutase (SOD), biodegradable materials like poly(DL‐lactide‐co‐glycolide) (PLGA), alginate, and chitosan were used for preparing PLGA microspheres and alginate–chitosan microspheres, which were used for encapsulating protein. Alginate–chitosan microspheres showed much higher entrapment efficiency (91.08% ± 1.28%) than that of PLGA microspheres (36.42% ± 1.81%). In vitro release study showed that SOD presented a sustained release character in the preparation of these biodegradable materials. After 15 days, 43.72% ± 0.43% of protein was released from alginate–chitosan microspheres, while there was 62.96% ± 3.95% of protein release from PLGA microspheres. However, alginate–chitosan demonstrated that it was a better material to control the burst release of protein from microspheres. Furthermore, SOD activity in microspheres was evaluated, and the results showed that microspheres protected the activity of protein to some extent. Finally, PLGA–alginate–chitosan complex microspheres were constructed and the release character in vitro demonstrated that this preparation could not only prolong the release of drug but also decrease the burst release. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Can accelerated aqueous aging simulate in vivo oxidation of gamma‐sterilized UHMWPE?
Authors: Mazzucco Daniel C. , Dumbleton John , Kurtz Steven M.
Published: February 2006

Oxidation of ultrahigh molecular weight polyethylene (UHMWPE) γ‐sterilized arthroplasty components occurs in vivo. Though accelerated in vitro protocols have been developed to test the relative oxidation resistance of various types of UHMWPE, it is desirable to develop an accelerated aging protocol that more closely approximates the in vivo environment. The goal of this study was to investigate the effects of temperature, solute, and oxygen partial pressure in aqueous media on the oxidation of γ‐sterilized UHMWPE, as the basis for the development of improved accelerated aging protocols. The accelerated oxidation behavior of γ‐sterilized GUR 1150 was studied at 60 and 70°C in an open vessel filled with distilled water or PBS in equilibrium with a controlled partial pressure of oxygen. The extent of oxidation was assessed using standardized mechanical and chemical evaluation techniques (small punch and Fourier transform infrared spectroscopy). Accelerated oxidation of UHMWPE was achieved in aqueous environments; however, both clinically relevant and nonrelevant oxidation species (e.g., aldehydes) were observed for long aging times at 60°C, and for all aging times at 70°C. These findings point the way to the development of an accelerated aging protocol. The current data, considered in conjunction with real‐time aging studies, suggest that a temperature between body temperature and 60°C may accelerate oxidative degradation without altering the oxidative patterns encountered in vivo. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
BOLD signal in the motor cortex shows a correlation with the blood volume of brain tumors
Authors: Lüdemann Lutz , Förschler Annette , Grieger Wolfgünter , Zimmer Claus
Published: February 2006

Purpose

To investigate whether and how the blood‐oxygenation‐level–dependent (BOLD) functional MRI (fMRI) signal is modified by brain tumors.

Materials and Methods

The BOLD signal depends on the perfusion, which in turn may be affected in the presence of a tumor. Some studies have demonstrated a reduced BOLD signal in the tumor‐bearing hemisphere. The BOLD signal variation in the motor cortex area was studied with finger tapping in a brain tumor group and a control group. An a priori volume‐of‐interest (VOI)‐based method was applied that allows quantification of the mean BOLD signal amplitude and extent of activated volume. BOLD signal amplitude and activated volume were correlated with the extent of edema, a mass effect on the central sulcus, tumor volume, distance of tumor to somatosensory cortex, and tumor blood volume.

Results

In the tumor group the ipsilateral activated volume was reduced by 21% (P = 0.025) and the mean signal amplitude was reduced by 16% (P = 0.004). The mean BOLD signal amplitude shows a significant correlation with the total intratumoral blood volume (P = 0.014).

Conclusion

We concluded that the peritumoral perfusion was reduced resulting due to a tumor aspirating perfusion (steal phenomenon). J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.
Vertebrae adjacent to spinal bone lesion are inconsistent reference markers: A magnetic resonance spectroscopic viewpoint
Authors: Rumpel Helmut , Chan Ling Ling , Chan Lai Peng , Png Meng Ai , Tan Raymond K.L. , Lim Winston E.H.
Published: February 2006

Purpose

To ascertain the suitability of vertebrae adjacent to spinal bone lesions as a signal intensity reference on MRI, and compare the MR spectroscopic appearance of vertebral body compression fractures due to malignant tumor infiltration, bone weakening (e.g., osteoporosis), and/or minor trauma.

Materials and Methods

Twenty‐five patients with spinal compression fractures underwent routine spinal MRI with an additional 1H MRS study protocol to assess the percent fat fraction of the compressed vertebrae as well as the adjacent bony environment. Peak areas for water and total lipid were calculated from short‐TE single‐voxel 1H MR spectra using the LCModel analyzing tool.

Results

There were consistent water‐only patterns in the fractured vertebra suggesting either near complete marrow replacement by malignant tissue or local edematous fluid/hemorrhage within the marrow spaces. However, the adjacent vertebrae showed a wide range of patterns from a dominant lipid signal to the inverse of a pronounced water level. These results far exceed the normal variation expected based on age and sex.

Conclusion

The results suggest that the adjacent vertebrae may not be an accurate reference, especially in diffusion‐weighted imaging (DWI), because of the large difference between the two compartments. Furthermore, in the case of gradient‐echo measurements, the in‐phase vs. opposed‐phase effects are significant. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.
Effects of green tea extract on the quality of bread made from unfrozen and frozen dough processes
Authors: Wang Rong , Zhou Weibiao , Yu Huei‐Huei , Chow Weng‐Fai
Published: February 2006

Two different green tea extracts (GTE‐A and ‐B) as a rich source of tea catechins were incorporated into a no‐time bread‐making process, where bread made from the unfrozen and frozen dough processes was compared by specific volume and texture profile. GTE‐A and ‐B both exhibited significant effects on bread volume and firmness, but to a different extent. GTE‐A with higher content of tea catechins (73%) at a level of 1.5 g kg−1 flour was found to lead to a significant reduction in bread volume in unfrozen dough process and an increment in firmness during storage for 4 days at ambient temperature (22 °C). GTE‐B, with a lower content of catechins (60%), had relatively mild effects on the bread quality. Significantly negative effects were evident starting at a higher level of 5.0 g kg−1 flour in unfrozen dough process. Frozen storage showed more predominant deteriorating effects than the GTEs over a period of 9 weeks frozen storage at −20 °C. Copyright © 2006 Society of Chemical Industry
Grafting to improve nitrogen‐use efficiency traits in tobacco plants
Authors: Ruiz Juan M , Rivero Rosa M , Cervilla Luis M , Castellano Rosa , Romero Luis
Published: February 2006

Nitrate plays a major role in the yield and quality of tobacco plants. This work explored the nitrogen‐use efficiency (NUE) and how it can be affected by grafting. Two experiments were designed: in the first, using six commercial tobacco cultivars, the best cultivar for the NUE was selected and analysed for foliar NO3− content, total N, nicotine and nitrate reductase (NR) activity. The results showed the cultivar H‐20 to have the best performance on NUE. It was further featured by the highest NR activity and total N and by the lowest NO3− and nicotine content, resulting in the highest foliar leaf biomass production and quality. In the second experiment it was tested whether the cultivar H‐20 could be used as rootstock to improve the NUE of the other cultivars under study. The results showed that the grafted plants had improved the NO3− assimilation with respect to non‐grafted plants. Hence grafting tobacco plants can be used as a quick and effective method to improve NUE, which has beneficial implications for human health and for a reduction in environmental pollution. Copyright © 2006 Society of Chemical Industry
Structural Studies on Syndiotactic 1,2‐Poly(1,3‐butadiene) by X‐Ray Measurements and Molecular Mechanics Calculations
Authors: Napolitano Roberto , Pirozzi Beniamino , Esposito Simona
Published: February 2006

Summary: Two samples of syndiotactic l,2‐poly(1,3‐butadiene) with different constitutional and configurational regularities were characterized by DSC analysis and X‐ray powder diffraction. Possible models of the crystal structure were obtained by molecular mechanics calculations performed with various sets of potential functions. X‐ray powder profiles calculated for these models were in good agreement with experiments. The agreement between simulated and experimental X‐ray powder profiles was improved by taking into account, in the calculated models, the presence of configurational defects. This indicates that configurational defects can be included in the crystal phase.

Projection along the b axis of a portion of the crystal structure of sPBD12 containing a [mm] triad in the energy minimum.

magnified image

Projection along the b axis of a portion of the crystal structure of sPBD12 containing a [mm] triad in the energy minimum.
Improved gradient‐echo 3D magnetic resonance imaging using pseudo‐echoes created by frequency‐swept pulses
Authors: Park Jang‐Yeon , DelaBarre Lance , Garwood Michael
Published: February 2006

Frequency‐swept pulses are not typically employed to excite spins in NMR. When used for selective excitation in MRI, such pulses do not produce a proper echo because the phase of the transverse magnetization varies in a quadratic manner across the slice or slab. Previously, frequency‐swept pulses such as the chirp pulse have been shown to offer an approach to reduce the peak radiofrequency power required for excitation. It has also been shown that chirp excitation produces a unique type of echo (dubbed “pseudo‐echo” here) and images can be generated from the resultant pseudo‐echoes using a quadratic reconstruction method (J.G. Pipe, Magn Reson Med 1995;33:24–33). The present work describes a general theory and methods for exciting spins with other types of frequency‐swept pulses (HSn pulses), which offer the advantage of delivering better excitation profiles than the chirp pulse. Here, pseudo‐echoes are produced with HSn pulses in conventional gradient‐echo 3D MRI, and high‐quality images are reconstructed using standard fast Fourier transformation. An optional apodization procedure using a sliding window function is also introduced. When the dynamic range of the analog‐to‐digital converter is limiting, signal‐to‐noise ratio of pseudo‐echo imaging is superior to that obtained with standard excitations. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
Detection of myocardial capillary orientation with intravascular iron‐oxide nanoparticles in spin‐echo MRI
Authors: Vignaud Alexandre , Rodriguez Ignacio , Ennis Daniel B. , DeSilva Ranil , Kellman Peter , Taylor Joni , Bennett Eric , Wen Han
Published: February 2006

In mammalian hearts the capillaries are closely aligned with the muscle fibers. We report our observation of a main‐field direction‐dependent contrast in MR spin‐echo (SE) images of the heart in the presence of Ferumoxtran‐10, an intravascular iron‐oxide nanoparticle contrast agent (CA). We describe a novel MRI method for mapping the preferential orientation of capillaries in the myocardial wall. The eigenvector corresponding to the minimum eigen value of the R2 relaxation rate tensor is consistent with the expected orientation of the capillary network. Preliminary results also demonstrate the feasibility of this method for in vivo application to rodent imaging. Magn Reson Med, 2006. Published © 2006 Wiley‐Liss, Inc.
Eosinophilia, myositis, and myasthenia gravis associated with a thymoma
Authors: Avni Irit , Sharabi Yehonatan , Sadeh Menachem , Buchman Aron S.
Published: February 2006

Hypereosinophilia has been associated with a wide variety of systemic disorders, including myositis. Myositis develops in a minority of patients with myasthenia gravis associated with a thymoma. We present a patient who developed a life‐threatening myopathy in which testing demonstrated the concurrence of hypereosinophilia, myositis, and myasthenia gravis associated with thymoma. Thymoma‐associated T‐cell abnormalities may well have contributed to this rare association. This case underscores the need to reevaluate constantly the presumed cause of clinical complaints, as more than one cause may be present. Muscle Nerve, 2006
A mathematical programming approach for improving the robustness of least sum of absolute deviations regression
Authors: Giloni Avi , Sengupta Bhaskar , Simonoff Jeffrey S.
Published: February 2006

This paper discusses a novel application of mathematical programming techniques to a regression problem. While least squares regression techniques have been used for a long time, it is known that their robustness properties are not desirable. Specifically, the estimators are known to be too sensitive to data contamination. In this paper we examine regressions based on Least‐sum of Absolute Deviations (LAD) and show that the robustness of the estimator can be improved significantly through a judicious choice of weights. The problem of finding optimum weights is formulated as a nonlinear mixed integer program, which is too difficult to solve exactly in general. We demonstrate that our problem is equivalent to a mathematical program with a single functional constraint resembling the knapsack problem and then solve it for a special case. We then generalize this solution to general regression designs. Furthermore, we provide an efficient algorithm to solve the general nonlinear, mixed integer programming problem when the number of predictors is small. We show the efficacy of the weighted LAD estimator using numerical examples. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2006
Typeness of personality profiles: a continuous person‐centred approach to personality data
Authors: Asendorpf Jens B.
Published: February 2006

I propose a new method of analysing personality profiles based on multiple traits. Personality profiles are regressed within individuals on prototypic profiles for personality types. To increase reliability, empirical Bayes estimates as obtained from hierarchical linear modelling (HLM) are used. The regression coefficients are interpreted as typeness, the extent to which the individual personality profile deviates from the mean profile in the sample consistent with the deviations of the personality types. These continuous parameters of typeness are subsequently used in between‐person analyses. This method was applied to two studies of Big Five profiles that were related to prototypic profiles for overcontrollers and undercontrollers. The typeness parameters, if reliable, showed a longitudinal stability and an external validity similar to the Big Five scales. The merits and limits of the proposed approach for the description of, and prediction from, personality are discussed. Copyright © 2006 John Wiley & Sons, Ltd.
Proteomic identification of alterations in metabolic enzymes and signaling proteins in hypokalemic nephropathy
Authors: Thongboonkerd Visith , Chutipongtanate Somchai , Kanlaya Rattiyaporn , Songtawee Napat , Sinchaikul Supachok , Parichatikanond Paisal , Chen Shui‐Tein , Malasit Prida
Published: February 2006

Hypokalemic nephropathy caused by prolonged K+ deficiency is associated with metabolic alkalosis, polydipsia, polyuria, growth retardation, hypertension, and progressive tubulointerstitial injury. Its pathophysiology, however, remains unclear. We performed gel‐based, differential proteomics analysis of kidneys from BALB/c mice fed with high‐normal‐K+ (HNK), low‐normal‐K+ (LNK), or K+‐depleted diet for 8 wk (n = 6 in each group). Plasma K+ levels were 4.62 ± 0.35, 4.46 ± 0.23, and 1.51 ± 0.21 mmol/L for HNK, LNK, and KD mice, respectively (p < 0.0001; KD vs. others). With comparable amounts of food intake, the KD mice drank significantly more water than the other two groups and had polyuria. Additionally, the KD mice had growth retardation, metabolic alkalosis, markedly enlarged kidneys, renal tubular dilation, intratubular deposition of amorphous and laminated hyaline materials, and tubular atrophy. A total of 33 renal proteins were differentially expressed between the KD mice and others, whereas only eight proteins were differentially expressed between the HNK and LNK groups, as determined by quantitative intensity analysis and ANOVA with Tukey's post hoc multiple comparisons. Using MALDI‐MS and/or quadrupole‐TOF MS/MS, 30 altered proteins induced by K+‐depletion were identified as metabolic enzymes (e.g., carbonic anhydrase II, aldose reductase, glutathione S‐transferase GT41A, etc.), signaling proteins (14–3‐3 ε, 14–3‐3 ζ, and cofilin 1), and cytoskeletal proteins (γ‐actin and tropomyosin). Some of these altered proteins, particularly metabolic enzymes and signaling proteins, have been demonstrated to be involved in metabolic alkalosis, polyuria, and renal tubular injury. Our findings may lead to a new road map for research on hypokalemic nephropathy and to better understanding of the pathophysiology of this medical disease when the functional and physiological significances of these altered proteins are defined.
The early responses of Arabidopsis thaliana cells to cadmium exposure explored by protein and metabolite profiling analyses
Authors: Sarry Jean‐Emmanuel , Kuhn Lauriane , Ducruix Céline , Lafaye Alexandra , Junot Christophe , Hugouvieux Véronique , Jourdain Agnès , Bastien Olivier , Fievet Julie B. , Vailhen Dominique , Amekraz Badia , Moulin Christophe , Ezan Eric , Garin Jérôme , Bourguignon Jacques
Published: February 2006

To get more insight into plant cell response to cadmium (Cd) stress, both proteomic and metabolomic “differential display” analyses were performed on Arabidopsis thaliana cells exposed to different concentrations of the toxic chemical. After a 24 h treatment, soluble proteins extracted from untreated and treated cells were separated by 2‐D‐PAGE and image analyses were performed to quantify and compare protein levels. Proteins up‐ and down‐regulated in response to Cd were identified by MS and mapped into specific metabolic pathways and cellular processes, highlighting probable activation of the carbon, nitrogen, and sulfur metabolic pathways. For some of these proteins, Northern blot and RT‐PCR analyses were performed to test transcript accumulation in response to Cd. In parallel, metabolite profiling analyses by LC coupled to ESI MS were initiated to better characterize the metabolic adaptation to the chemical stress. This study revealed that the main variation at the metabolite level came from the presence of six different families of phytochelatins, in A. thaliana cells treated with Cd, whose accumulation increases with Cd concentrations. Taken together these data provide an overview of the molecular and cellular changes elicited by Cd exposure.
Human colostrum: Identification of minor proteins in the aqueous phase by proteomics
Authors: Palmer David J. , Kelly Van C. , Smit Anne‐Marie , Kuy Sulee , Knight Catriona G. , Cooper Garth J.
Published: February 2006

Human colostrum is an important source of protective, nutritional and developmental factors for the newborn. We have investigated the low abundance proteins in the aqueous phase of human colostrum, after depletion of the major proteins secretory IgA, lactoferrin, alpha‐lactalbumin and HSA by immunoabsorption, using 2‐D LC and gel‐based proteomic methods. One hundred and fifty‐one proteins were identified, 83 of which have not been previously reported in human colostrum, or milk. This is the first comprehensive proteomic analysis of human colostrum produced during the first 48 h of lactation.