bluuebunny/crossref_metadata_2025 huggingface dataset:
Surface characterization and cell response of a PLA/CaP glass biodegradable composite material
Authors: Navarro M. , Engel E. , Planell J. A. , Amaral I. , Barbosa M. , Ginebra M. P.
Published: August 2007

Bioabsorbable materials are of great interest for bone regeneration applications, since they are able to degrade gradually as new tissue is formed. In this work, a fully biodegradable composite material containing polylactic acid (PLA) and calcium phosphate (CaP) soluble glass particles has been characterized in terms of surface properties and cell response. Cell cultures were performed in direct contact with the materials and also with their extracts, and were evaluated using the MTT assay, alkaline phosphatase activity, and osteocalcin measurements. The CaP glass and PLA were used as reference materials. No significant differences were observed in cell proliferation with the extracts containing the degradation by‐products of the three materials studied. A relation between the materials wettability and the material‐cell interactions at the initial stages of contact was observed. The most hydrophilic material (CaP glass) presented the highest cell adhesion values as well as an earlier differentiation, followed by the PLA/glass material. The incorporation of glass particles into the PLA matrix increased surface roughness. SEM images showed that the heterogeneity of the composite material induced morphological changes in the cells cytoskeleton. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Low molecular weight molecules of oyster nacre induce mineralization of the MC3T3‐E1 cells
Authors: Rousseau Marthe , Boulzaguet Hélène , Biagianti Julie , Duplat Denis , Milet Christian , Lopez Evelyne , Bédouet Laurent
Published: August 2007

The nacre layer from the pearl oyster shell is considered as a promising osteoinductive biomaterial. Nacre contains one or more signal molecules capable of stimulating bone formation. The identity and the mode of action of these molecules on the osteoblast differentiation were analyzed. Water‐soluble molecules from nacre were fractionated according to dialysis, solvent extraction, and reversed‐phase HPLC. The activity of a fraction composed of low molecular weight molecules in the mineralization of the MC3T3‐E1 extracellular matrix was investigated. Mineralization of the preosteoblast cells was monitored according to alizarin red staining, Raman spectroscopy, scanning electron microscopy, and quantitative RT‐PCR. Molecules isolated from nacre, ranging from 50 to 235 Da, induced a red alizarin staining of the preosteoblasts extracellular matrix after 16 days of culture. Raman spectroscopy demonstrated the presence of hydroxyapatite (HA) in samples treated with these molecules. Scanning electron microscopy pictures showed at the surface of the treated cells the occurrence of clusters of spherical particles resembling to HA. The treatment of cells with nacre molecules accelerated expression of collagen I and increased the mRNA expression of Runx2 and osteopontin. This study indicated that the nacre molecules efficient in bone cell differentiation are certainly different from proteins, and could be useful for in vivo bone repair. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
T cell subset distributions following primary and secondary implantation at subcutaneous biomaterial implant sites
Authors: Rodriguez Analiz , Voskerician Gabriela , Meyerson Howard , MacEwan Sarah R. , Anderson James M.
Published: August 2007

Synthetic biomaterials are considered to be nonimmunogenic. Therefore, the role that adaptive immunity may play in the host response to implanted synthetic biomaterials has not been extensively studied. Cardinal features of adaptive immunity include specificity and T cell responses, which are greater and more effective with upregulation of activation receptors upon rechallenge. We compared the primary and secondary in vivo host response to three synthetic biomaterials: Elasthane 80A, silicone rubber, and polyethylene terephthalate using a cage implant model in Sprague Dawley rats. The synthetic biomedical polymers were subcutaneously implanted in cages for 14 days. Following explantation of the cages and a 2 week healing period, rats were implanted with cages containing the biomedical polymers for an additional 2 weeks. The cellular exudates within the cages were analyzed 4, 7, and 14 days post primary and secondary implantation by flow cytometry for the following cell types: T cells (inclusive of CD8+, CD4+, and CD4+/CD25+ subsets), B cells, granulocytes, and macrophages. At day 14 following secondary implantation, there was an increase in T cells, granulocytes, and macrophages in the exudates when compared with primary implantation for all groups inclusive of the empty cage control. However, CD4+/CD8+ ratios, the percentage of CD4+CD25+ T cells, and the macrophage surface adhesion/fusion did not vary significantly upon secondary implantation. Despite a quantitative increase in T cells following secondary biomaterial exposure, T cell subset distribution did not change, indicating nonspecific recruitment rather than an adaptive immune response. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Would a rising yen mean global turmoil?
Authors: Tokic Damir , Tokic Stijepko
Published: August 2007

Since 1995, Japan has had low interest rates and a depreciating value of the yen against the U.S. dollar. So global investors have borrowed funds in Japan to invest in other global markets. But any indication of change in fundamentals can cause severe global financial turmoil, warn the authors of this article. They explain what signs investors need to watch to avert disaster, and how investors should protect themselves. © 2007 Wiley Periodicals, Inc.
Role of TIEG1 in biological processes and disease states
Authors: Subramaniam Malayannan , Hawse John R. , Johnsen Steven A. , Spelsberg Thomas C.
Published: August 2007

A novel TGFβ Inducible Early Gene‐1 (TIEG1) was discovered in human osteoblast (OB) cells by our laboratory. Over the past decade, a handful of laboratories have revealed a multitude of organismic, cellular, and molecular functions of this gene. TIEG1 is now classified as a member of the 3 zinc finger family of Krüppel‐like transcription factors (KLF10). Other closely related factors [TIEG2 (KLF11) and TIEG3/TIEG2b] have been reported and are briefly compared. As described in this review, TIEG1 is shown to play a role in regulating estrogen and TGFβ actions, the latter through the Smad signaling pathway. In both cases, TIEG1 acts as an inducer or repressor of gene transcription to enhance the TGFβ/Smad pathway, as well at other signaling pathways, to regulate cell proliferation, differentiation, and apoptosis. This review outlines TIEG1's molecular functions and roles in skeletal disease (osteopenia/osteoporosis), heart disease (hypertrophic cardiomyopathy), and cancer (breast and prostate). J. Cell. Biochem. 102: 539–548, 2007. © 2007 Wiley‐Liss, Inc.
Repair of large full‐thickness articular cartilage defects by transplantation of autologous uncultured bone‐marrow‐derived mononuclear cells
Authors: Chang Fei , Ishii Tomoo , Yanai Takaji , Mishima Hajime , Akaogi Hiroshi , Ogawa Takeshi , Ochiai Naoyuki
Published: August 2007

The objective of this study was to investigate the feasibility of autologous uncultured bone marrow‐derived mononuclear cell transplantation in large full‐thickness cartilage regeneration. After fixing with a hinged external fixator, the entire surface of the left tibial plateau was resected and large full‐thickness cartilage defects were formed in 48 rabbits. Animals were divided into four groups: autologous uncultured bone marrow‐derived mononuclear cells with fibrin gel (BMC), autologous uncultured peripheral blood‐derived mononuclear cells with fibrin gel (PBC), fibrin gel alone (GEL), or nothing (CON) transplanted to the articular cavity 7 days after the operation. The rabbits were killed 8 or 12 weeks after the operation. The repair of defects was investigated histologically and scored using a histological and histochemical grading scale that was modified from the International Cartilage Repair Society Visual Histological Assessment Scale. To evaluate the regenerated cartilage, we also morphometrically measured the staining area positive for Safranin‐O or type II collagen and calculated the percentages of the positive staining areas with respect to the regenerated soft tissue area. Histological findings showed that the BMC group had superior cartilage repair compared with the other groups, and that the PBC and CON group showed better cartilage repair than did the GEL group. Histological scores and morphometrical measurements also showed the same results quantitively. The transplantation of autologous uncultured bone marrow‐derived mononuclear cells contributes to articular cartilage repair. The easy and safe method used in this study is potentially viable for clinical application. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:18–26, 2008
Circulating cells with osteogenic potential are physiologically mobilized into the fracture healing site in the parabiotic mice model
Authors: Kumagai Ken , Vasanji Amit , Drazba Judith A. , Butler Robert S. , Muschler George F.
Published: August 2007

Based on the accumulating evidence of osteogenic cells present in the systemic circulation, we hypothesized that circulating osteogenic connective tissue progenitors (CTPs) home to fracture site and contribute to skeletal repair. Parabiotic animals were formed by surgically conjoining transgenic mice constitutively expressing green fluorescent protein (GFP) in no erythroid tissue and syngeneic wild‐type mice. After 3 weeks parabionts, equilibrium in blood chimerism between partners was established. A transverse fibular fracture was made in the contralateral hind limb of the conjoined wild‐type partner. The contribution of circulating cells to the fracture callus was assessed based on analysis of GFP+ cells and co‐localization of alkaline phosphatase (AP) staining nonfracture and at 1, 2, 3, and 4 weeks after fracture. Histomorphometric analysis at the fracture site showed significant increase of GFP+ cells after 2 (5.4%) and 3 (5.6%) weeks compared to nonfractured controls (1.7%). Of the GFP+ cells, percentage of the cells expressing AP activity at 1 (37.4%) and 2 (85.3%) weeks postfracture time was statistically higher than that in nonfractured controls (10.8%). The rate of mobilization of circulating osteogenic CTPs to fracture callus was also examined using 1 week parabionts at week 0–1 and week 1–2 postfracture. There was significant increase of GFP+/AP+ cells from week 0–1 (0.1%) and week 1–2 (1.8%). These data indicate that circulating osteogenic CTPs are mobilized to fracture site and contribute to osteogenesis in the early stage of fracture healing. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:165–175, 2008
Expression profiling reveals alternative macrophage activation and impaired osteogenesis in periprosthetic osteolysis
Authors: Koulouvaris Panagiotis , Ly Khanh , Ivashkiv Lionel B. , Bostrom Mathias P. , Nestor Bryan J. , Sculco Thomas P. , Purdue P. Edward
Published: August 2007

Interactions between periprosthetic cells and prosthetic wear debris have been recognized as an important event in the development of osteolysis and aseptic loosening. Although the ability of wear debris to activate pro‐inflammatory macrophage signaling has been documented, the full repertoire of macrophage responses to wear particles has not been established. Here, we examined the involvement of alternative macrophage activation and defective osteogenic signaling in osteolysis. Using real‐time RT‐PCR analysis of periprosthetic soft tissue from osteolysis patients, we detected elevated levels of expression of alternative macrophage activation markers (CHIT1, CCL18), chemokines (IL8, MIP1 α) and markers of osteoclast precursor cell differentiation and multinucleation (Cathepsin K, TRAP, DC‐STAMP) relative to osteoarthritis controls. The presence of cathepsin K positive multinuclear cells was confirmed by immunohistochemistry. Reduced expression levels of the osteogenic signaling components BMP4 and FGF18 were detected. Expression levels of TNF‐α, IL‐6, and RANKL were unchanged, while the anti‐osteoclastogenic cytokine OPG was reduced in osteolysis patients, resulting in elevated RANKL:OPG ratios. In vitro studies confirmed the role of particulate debris in alternative macrophage activation and inhibition of osteogenic signaling. Taken together, these results suggest involvement in osteolysis of alternative macrophage activation, accompanied by elevated levels of various chemokines. Increased recruitment and maturation of osteoclast precursors is also observed, as is reduced osteogenesis. These findings provide new insights into the molecular pathogenesis of osteolysis, and identify new potential candidate markers for disease progression and therapeutic targeting. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:106–116, 2008
The evolution of the management of regional lymph nodes in melanoma
Authors: Landry Christine S. , McMasters Kelly M. , Scoggins Charles R.
Published: August 2007

The last two decades have seen sweeping changes in the surgical approach to melanoma. Traditionally, patients without evidence of nodal metastases were considered for elective lymph node dissection. This approach placed many patients at risk of morbidity while many derived no benefit. As investigators gained a deeper understanding of melanoma and lymphatic biology, newer methods of managing regional lymph nodes were sought. The advent of sentinel node biopsy has radically changed the approach to melanoma. J. Surg. Oncol. 2007;96:316–321. © 2007 Wiley‐Liss, Inc.
Conviviality and everyday life: the appeal of new areas of London for visitors
Authors: Maitland Robert
Published: August 2007

Literature on tourism development in converted cities or new districts of polycentric cities emphasises planned processes to create attractions, often resulting in standardised tourism zones. The demands and experience of tourists themselves have been neglected. Qualitative research with overseas visitors to new tourism areas suggests that character and sense of place that visitors enjoy derives from a combination of unlike elements, ‘lashed up’ to create a distinctive place, in which everyday life plays an important role. Rather than familiar stories of conflict between ‘hosts’ and ‘guests’, the emphasis in some areas is on conviviality among different groups of city users. Copyright © 2007 John Wiley & Sons, Ltd.
Linear functionals on nonlinear spaces and applications to problems from viscoplasticity theory
Authors: Pompe Waldemar
Published: August 2007

A classical result in the theory of monotone operators states that ifCis a reflexive Banach space, and an operatorA:C→C*is monotone, semicontinuous and coercive, thenAis surjective. In this paper, we define the ‘dual space’C*of a convex, usually not linear, subsetCof some Banach spaceX(in general, we will haveC*⊃X*) and prove an analogous result. Then, we give an application to problems from viscoplasticity theory, where the natural space to look for solutions is not linear. Copyright © 2007 John Wiley & Sons, Ltd.
Hydrolyzed fumonisins HFB1 and HFB2 are acylated in vitro and in vivo by ceramide synthase to form cytotoxic N‐acyl‐metabolites
Authors: Seiferlein Michaela , Humpf Hans‐Ulrich , Voss Kenneth A. , Sullards M. Cameron , Allegood Jeremy C. , Wang Elaine , Merrill Alfred H.
Published: August 2007

Fumonisins B1 and B2 (FB1 and FB2) are the most abundant members of the fumonisins ‐ mycotoxins that are produced by Fusarium verticillioides and are natural inhibitors of ceramide synthase. Their hydrolyzed forms, HFB1 and HFB2 (also called AP1 and AP2) are found in some foods, and they are not only inhibitors of ceramide synthase but also undergo acylation by this enzyme. This study characterized the conversion of HFB1 and HFB2 by ceramide synthase to their respective N‐acylated metabolites using rat liver microsomes and palmitoyl‐CoA or nervonoyl‐CoA as cosubstrates, and examined animals that had been dosed with hydrolyzed fumonisins to ascertain if acylation occurs in vivo. Using an HPLC‐MS/MS method that allowed the sensitive and selective detection of the acylation products, both HFB1 and HFB2 were found to be metabolized in vitro to nervonoyl‐ or palmitoyl‐HFB1 and ‐HFB2 (i. e. C24:1‐HFB1/2 and C16‐HFB1/2, respectively). The apparent vmax was considerably higher for formation of C24:1HFB1 (157 pmol/min/mg protein) than for formation of C16HFB1 (8.7 pmol/min/mg protein). The acylation products also inhibited ceramide synthase and significantly reduced the number of viable cells in an in vitro [3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT)] assay using a human colonic cell line (HT29). Furthermore, HPLC‐MS/MS analysis of tissues from rats given intraperitoneal doses of HFB1 confirmed that formation of N‐acyl‐HFB1 occurs in vivo to produce metabolites with fatty acids of various chain lengths. The contribution of acylated HFB1 and HFB2 metabolites to fumonisin toxicity in vivo warrants further investigation.
An NMR, IR and theoretical investigation of 1H Chemical Shifts and hydrogen bonding in phenols
Authors: Abraham Raymond J. , Mobli Mehdi
Published: August 2007

The change in 1H NMR chemical shifts upon hydrogen bonding was investigated using both experimental and theoretical methods. The 1H NMR spectra of a number of phenols were recorded in CDCl3 and DMSO solvents. For phenol, 2‐ and 4‐cyanophenol and 2‐nitrophenol the OH chemical shifts were measured as a function of concentration in CDCl3. The plots were all linear with concentration, the gradients varying from 0.940 (phenol) to 7.85 (4‐cyanophenol) ppm/M because of competing inter‐ and intramolecular hydrogen bonding. Ab initio calculations of a model acetone/phenol system showed that the OH shielding was linear with the H…OC distance (R) for R < 2.1 Å with a shielding coefficient of − 7.8 ppm/Å and proportional to cos2φ where φ is the H…OCC dihedral angle. Other geometrical parameters had little effect. It was also found that the nuclear shielding profile is unrelated to the hydrogen bonding energy profile. The dependence of the OH chemical shift on the π density on the oxygen atom was determined as ca 40 ppm/π electron. This factor is similar to that for NH but four times the value for sp2 hybridized carbon atoms. The introduction of these effects into the CHARGE programme allowed the calculation of the 1H chemical shifts of the compounds studied. The CHARGE calculations were compared with those from the ACD database and from GIAO calculations. The CHARGE calculations were more accurate than other calculations both when all the shifts were considered and also when the OH shifts were excluded. The calculations from the ACD and GIAO approaches were reasonable when the OH shifts were excluded but not as good when all the shifts were considered. The poor treatment of the OH shifts in the GIAO calculations is very likely due to the lack of explicit solvent effects in these calculations. Copyright © 2007 John Wiley & Sons, Ltd.
Complete 1H NMR spectral fingerprint of huperzine A
Authors: Niemitz Matthias , Laatikainen Reino , Chen Shao‐Nong , Kleps Robert , Kozikowski Alan P. , Pauli Guido F.
Published: August 2007

Complete analysis of the 1H NMR spectrum of huperzine A, 1‐amino‐13‐ethylidene‐11‐methyl‐6‐aza‐tricyclo[7.3.1.02, 7]trideca‐2(7),3,10‐trien‐5‐one, a Lycopodium alkaloid and anti‐Alzheimer drug lead containing an ABCD(E)(MN)(OP)X3Y3–type system of 15 nonexchangeable proton spins, is reported for the first time, and earlier assignments are corrected. The complete 1H parameter set of 11 chemical shifts clarifies the diastereotopism of both methylene groups, and provides a total of 38 observed H,H‐couplings including 31 long‐range (4–6J) connectivities. The NMR data is consistent with the comparatively rigid alicyclic backbone predicted by molecular mechanics calculations, and forms the basis for 1H NMR fingerprint analysis for the purpose of dereplication, purity analysis, and elucidation of structural analogs. Copyright © 2007 John Wiley & Sons, Ltd.
3‐Oxo‐12α‐hydroxyfriedelane from Maytenus gonoclada: structure elucidation by 1H and 13C chemical shift assignments and 2D‐NMR spectroscopy
Authors: Oliveira Mauro Lúcio G. , Duarte Lucienir Pains , Silva Grácia Divina F. , Filho Sidney Augusto Vieira , Knupp Vagner Fernandes , Alves Fernando Gomes P.
Published: August 2007

The compounds 3‐oxofriedelane (1), 3β‐hydroxyfriedelane (2), 3,11‐dioxofriedelane (3), 3,16‐dioxofrie delane (4) and 3‐oxo‐12α‐hydroxyfriedelane (5) were isolated from the hexane extract of Maytenus gonoclada Mart. (Celastraceae) leaves. Structural formula and the stereochemistry of the new pentacyclic triterpene 3‐oxo‐12α‐hydroxyfriedelane (5) were established through 1H and 13C NMR and DEPT 135 spectral data including 2D experiments (HMBC, HMQC, COSY, and NOESY) and mass spectrometry (GC‐MS). Copyright © 2007 John Wiley & Sons, Ltd.
Nodular‐type muscle sarcoidosis developing after a dog bite
Authors: Koide Y. , Ishihara H. , Kanda F.
Published: August 2007

We report a 46‐year‐old woman who experienced swelling of the right thigh around the wound caused by a dog bite. Physical findings, laboratory findings, imaging studies, and muscle biopsy showed that this was nodular‐type muscle sarcoidosis. This is an unusual case of sarcoidosis, and the possibility is discussed that a dog bite may serve as a trauma to trigger sarcoidosis in genetically predisposed individuals. Muscle Nerve, 2007
Multiscale aggregating discontinuities: A method for circumventing loss of material stability
Authors: Belytschko Ted , Loehnert Stefan , Song Jeong‐Hoon
Published: August 2007

New methods for the analysis of failure by multiscale methods that invoke unit cells to obtain the subscale response are described. These methods, called multiscale aggregating discontinuities, are based on the concept of ‘perforated’ unit cells, which exclude subdomains that are unstable, i.e. exhibit loss of material stability. Using this concept, it is possible to compute an equivalent discontinuity at the coarser scale, including both the direction of the discontinuity and the magnitude of the jump. These variables are then passed to the coarse‐scale model along with the stress in the unit cell. The discontinuity is injected at the coarser scale by the extended finite element method. Analysis of the procedure shows that the method is consistent in power and yields a bulk stress–strain response that is stable. Applications of this procedure to crack growth in heterogeneous materials are given. Copyright © 2007 John Wiley & Sons, Ltd.
Outcomes of a two‐drug chemotherapy regimen for intraocular retinoblastoma
Authors: Zage Peter E. , Reitman Aaron J. , Seshadri Roopa , Weinstein Joanna L. , Mets Marilyn B. , Zeid Janice Lasky , Greenwald Mark J. , Strauss Lewis C. , Goldman Stewart
Published: August 2007

Background

Retinoblastoma is the most common intraocular tumor of childhood. Vision salvage rates in advanced cases are less than ideal, and the optimal treatment for intraocular retinoblastoma has not been established. We report the results of an institutional retinoblastoma treatment trial to determine the vision salvage rates and toxicity of a regimen combining carboplatin and etoposide with focal retinal therapy.

Procedure

Twenty‐nine patients diagnosed with retinoblastoma in 48 eyes were treated between 1992 and 2004 with at least six cycles of carboplatin and etoposide combined with focal retinal therapy.

Results

The response rate of eyes after six cycles of chemotherapy was 85.4%. Twenty‐two eyes were enucleated, but only seven eyes received EBRT. The vision salvage rate without EBRT was 82.6% for eyes with Reese‐Ellsworth (R‐E) groups I–IV tumors and 20% for eyes with R‐E group V tumors. The vision salvage rate without EBRT for eyes with Murphree groups A and B tumors was 77.3% but was only 26.9% for eyes with groups C and D tumors. Acute side effects were minimal.

Conclusions

The combination of carboplatin and etoposide with focal therapy is a well‐tolerated regimen that has acceptable vision salvage rates for R‐E groups I–IV and Murphree groups A and B retinoblastoma. This combination avoids the use of EBRT and the toxicity of additional chemotherapy agents. However, patients with R‐E group V and Murphree groups C and D retinoblastoma have poorer outcomes and require more intensive therapy. Pediatr Blood Cancer 2008;50:567–572. © 2007 Wiley‐Liss, Inc.
Errorless learning: Review and practical application for teaching children with pervasive developmental disorders
Authors: Mueller Michael M. , Palkovic Christine M. , Maynard Cynthia S.
Published: August 2007

Errorless learning refers to a variety of discrimination learning techniques that eliminate or minimize responding to incorrect choices. This article describes experimental roots of errorless learning and applied errorless strategies. Specifically, previous research on stimulus fading, stimulus shaping, response prevention, delayed prompting, superimposition with stimulus fading, and superimposition with stimulus shaping are discussed. Educational applications for children with Pervasive Developmental Disorders (PDD) are presented for each technique so that school psychologists, educators, and teachers working with children with PDD can understand the underpinnings and practical applications of errorless techniques to use in skill acquisition programming in school settings. © 2007 Wiley Periodicals, Inc. Psychol Schs 44: 691–700, 2007.
Physician collaboration involving students with Autism Spectrum Disorders
Authors: Ellis Cynthia R. , Lutz Richard E. , Schaefer G. Bradley , Woods Kathryn E.
Published: August 2007

Each year, an increasing number of children and adolescents are diagnosed with an Autism Spectrum Disorder (ASD). ASDs involve impairment to an individual's social, language, and behavioral functioning. Due to the complexity of this disorder, a comprehensive, multidisciplinary assessment and treatment approach is recommended in order to meet the unique needs of these individuals. This article discusses the role of the medical team in this interdisciplinary process and provides a review of the biomedical issues encountered by this population, including associated medical conditions and medically based treatment options. A case example is also described demonstrating the collaborative treatment approach that is recommended when working with individuals with ASDs. © 2007 Wiley Periodicals, Inc. Psychol Schs 44: 737–747, 2007.
Eine Filmkamera für Moleküle. Bewegung von Atomkernen in Molekülen
Authors: Ergler Thorsten , Rudenko Artem , Moshammer Robert , Ullrich Joachim
Published: August 2007

Eine weiterentwickelte Femtosekunden‐Laserspektroskopie erlaubt es erstmals, die Dynamik des Deuterium‐Moleküls als Film zu visualisieren. Es ist eines der schnellsten molekularen Systeme in der Natur. Bei dem Verfahren ionisiert ein starker Pumppuls das Molekül zunächst einfach, ein Probepuls schließlich vollständig, so dass es explodiert. Die Variation des Zeitabstands zwischen beiden Pulsen erlaubt in Kombination mit einem Reaktionsmikroskop die präzise Vermessung der Moleküldynamik in Raum und Zeit. Alternativ stößt der erste Puls das neutrale D2‐Molekül an, ohne es zu ionisieren. In diesem Fall schwingt es als “Quantenpendel”, das auch zur Basis eines neuen Zeitstandards werden könnte. Die Technik soll es in Zukunft ermöglichen, chemische Reaktionen auf der Quantenebene zu manipulieren. Erste Experimente an Methan laufen bereits.
Pierre Gassendi und die Kopernikanische Zeitenwende. Das erste Großexperiment der Physik
Authors: Risch Matthias
Published: August 2007

Das heliozentrische Weltbild konnte sich lange Zeit nicht durchsetzen, weil aus der auf Aristoteles fußenden Impetus‐Theorie gefolgert wurde, die Erde sei unbewegt. Die Schiffsexperimente des Franzosen Pierre Gassendi im Jahre 1640 sowie seine Experimente mit dem Fallrad widerlegten diese Bewegungstheorie. Sie ebneten damit dem heliozentrischen Weltbild und moderner experimenteller Wissenschaft den Weg.
Die Flüssigmetall‐Neutronenquelle MEGAPIE
Authors: Fazio Concetta
Published: August 2007

Der verbrauchte Kernbrennstoff aus Atomkraftwerken enthält eine Reihe von Radionukliden mit langer Halbwertszeit und hoher Radiotoxizität. Das Forschungszentrum Karlsruhe untersucht gemeinsam mit europäischen Partnern, wie man die Transurane umwandeln (transmutieren) kann, um diesen langen Zeitraum auf einige hundert Jahre zu verkürzen. Am Schweizer Paul Scherrer Institut wurde hierzu kürzlich das Megawatt‐Pilot‐Experiment (MEGAPIE) erfolgreich durchgeführt. MEGAPIE ist eine intensive Neutronenquelle, wie sie als wichtige Großkomponente in Anlagen eingesetzt werden soll, in denen langlebige Isotope durch Neutronenbeschuss umgewandelt werden.
Proteomic analysis of differentially expressed proteins in Penaeus vannamei hemocytes upon Taura syndrome virus infection
Authors: Chongsatja Phattara‐orn , Bourchookarn Apichai , Lo Chu Fang , Thongboonkerd Visith , Krittanai Chartchai
Published: August 2007

To understand molecular responses of crustacean hemocytes to virus infection, we applied 2‐DE proteomics approach to investigate altered proteins in hemocytes of Penaeus vannamei during Taura syndrome virus (TSV) infection. At 24 h postinfection, quantitative intensity analysis and nano‐LC‐ESI‐MS/MS revealed 11 forms of 8 proteins that were significantly up‐regulated, whereas 9 forms of 5 proteins were significantly down‐regulated in the infected shrimps. These altered proteins play important roles in host defense (hemocyanin, catalase, carboxylesterase, transglutaminase, and glutathione transferase), signal transduction (14‐3‐3 zeta), carbohydrate metabolism (acetylglucosamine pyrophosphorylase), cellular structure and integrity (beta‐tubulin, beta‐actin, tropomyosin, and myosin), and ER‐stress response (protein disulfide isomerase). Semiquantitative RT‐PCR and Western blot analysis confirmed the upregulation of 14‐3‐3 at both mRNA and protein levels. Interestingly, several altered protein spots were identified as fragments of hemocyanin. Mass spectrometric analysis showed that the hemocyanin spots at acidic and basic regions represented the C‐ and N‐terminal hemocyanin fragments, respectively. As three‐quarters of C‐terminal fragments were up‐regulated, whereas two‐thirds of N‐terminal hemocyanin fragments were down‐regulated, we therefore hypothesize that C‐ and N‐terminal hemocyanin fragments may have differential roles in hemocytes. Further investigation of these data may lead to better understanding of the molecular responses of crustacean hemocytes to TSV infection.
Control of photoisomerization of CC double bond by hydrogen bonding and photoinduced hydrogen atom transfer
Authors: Azechi Yousuke , Takemura Keiko , Shinohara Yoshihiro , Nishimura Yoshinobu , Arai Tatsuo
Published: August 2007

Olefins with a phenathroline ring and a pyrrole ring were prepared and hydrogen atom transfer reaction in the excited singlet state was observed. The tautomer produced in the excited singlet state has lifetime of 30–50 ps for cis‐1 and c,t‐2 and with fluorescence maximum at longer wavelength region at 640 nm. The compound 1 exhibited photochromic behavior with its absorption maximum changing between 380 nm and 440 nm, while 2 exhibited only the small change of the absorption spectra on photoirradiation. Copyright © 2007 John Wiley & Sons, Ltd.
Acceleration effect of five‐membered cyclic dithiocarbonate on an epoxy–amine curing system
Authors: Horikiri Masashi , Sudo Atsushi , Endo Takeshi
Published: August 2007

A bifunctional cyclic five‐membered dithiocarbonate (DTC), having a bisphenol A structure, was found to be an effective accelerator for a epoxy–amine curing system comprised of bisphenol A diglycidyl ether and amine‐terminated polypropylene glycol. The acceleration effect was evaluated by monitoring the time‐dependence of the storage modulus of the reaction mixture with a dynamic mechanical analyzer. The reactions involved in the curing system were investigated in detail by performing a series of model reactions using the corresponding monofunctional monomers. This investigation revealed that (1) DTC reacted with amine rapidly, (2) the reaction afforded the corresponding adduct having a thiourethane and thiol moieties, and (3) the thiol reacted rapidly with epoxide. The thiourethane moiety incorporated into the resulting adduct effectively catalyzed the reaction of epoxide and amine, and this catalysis was the predominant mechanism for the acceleration effect arisen by the addition of DTC. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4606–4611, 2007
Synthesis and characterization of spherical and hemispherical polyepoxide micrometer‐sized particles of narrow size distribution by a single‐step swelling of uniform polystyrene template microspheres with glycidyl methacrylate
Authors: Omer‐Mizrahi Melany , Margel Shlomo
Published: August 2007

Polystyrene template microspheres of narrow size distribution were prepared by dispersion polymerization of styrene in a mixture of ethanol and 2‐methoxy ethanol. Spherical and hemispherical polystyrene/poly(glycidyl methacrylate) microspheres of narrow size distribution were prepared by a single‐step swelling of the polystyrene template microspheres with the swelling solvent monomer glycidyl methacylate, followed by polymerization of the monomer within the swollen template microspheres at 73 °C. Uniform polystyrene/poly(glycidyl methacylate‐ethylene glycol dimethacrylate) polyepoxide composite microspheres were synthesized similarly, substituting glycidyl methacylate for glycidyl methacylate and ethylene glycol dimethacrylate. Uniform crosslinked poly(glycidyl methacylate‐ethylene glycol dimethacrylate) polyepoxide microspheres have been prepared by dissolution of the PS template polymer of the former composite microspheres. Particles with different properties, for example size, size distribution, shape, surface morphology, surface area, and so forth, were prepared by changing various parameters belonging to the swelling and/or polymerization steps, for example, volume of the swelling monomer/s and/or the swelling solvent dibutyl phthalate. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4612–4622, 2007
Polylactide compositions. II. Correlation between morphology and main properties of PLA/calcium sulfate composites
Authors: Pluta Miroslaw , Murariu Marius , Da Silva Ferreira Amália , Alexandre Michael , Galeski Andrzej , Dubois Philippe
Published: August 2007

Starting from calcium sulfate (gypsum) as fermentation by‐product of lactic acid production process, high performance composites have been produced by melt‐blending polylactide (PLA, L/D isomer ratio of 96:4) and β‐anhydrite II (AII) filler, that is, calcium sulfate hemihydrate previously dehydrated at 500 °C. Characterized by attractive mechanical and thermal properties due to good filler dispersion throughout the polyester matrix, these composites are interesting for potential use as biodegradable rigid packaging. Physical characterization of selected composites filled with 20 and 40 wt % AII has been performed and compared to processed unfilled PLA with similar amorphous structure. State of dispersion of the filler particles and interphase characteristic features have been investigated using light microscopy (LM) and scanning electron microscopy (SEM). Addition of AII did not decrease PLA thermal stability as revealed by thermogravimetry analyses (TGA) and allowed reaching a slight increase of PLA crystallizability during melt crystallization and upon heating from the glassy, amorphous state (DSC). It was found by thermomechanical measurements (DMTA) that the AII filler increased pronouncedly storage modulus (E′) of the composites in comparison with PLA in a broad temperature range. The X‐ray investigations showed stable/unchanged crystallographic structure of AII during processing with molten PLA and in the composite system. The notable thermal and mechanical properties of PLA–AII composites are accounted for by the good filler dispersion throughout the polyester matrix confirmed by morphological studies, system stability, and favorable interactions between components. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2770–2780, 2007
Rheological properties of HyperMacs—long‐chain branched analogues of hyperbranched polymers
Authors: Dodds Jonathan M. , De Luca Edoardo , Hutchings Lian R. , Clarke Nigel
Published: August 2007

HyperMacs are long chain branched analogues of hyperbranched polymers, differing only in the sense that they have polymer chains, rather than monomers between branch points. Although the building blocks for HyperMacs and AB2 macromonomers can be well defined in terms of molecular weight and polydispersity, the nature of the coupling strategy adopted for the synthesis of the HyperMacs results in branched polymers with a distribution of molecular weights and architectures. Melt rheology showed polystyrene HyperMacs to be thermorheologically simple, obeying William–Landel–Ferry behavior. Zero shear viscosities of the polymers were shown to increase with average molecular weight and the melts display shear‐thinning behavior. HyperMacs showed little evidence for relaxation by reptation and the rheological behavior agreed well with the Cayley tree model for hierarchical relaxation in tube models of branched polymers. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2762–2769, 2007
Mutagenesis study of rice nonspecific lipid transfer protein 2 reveals residues that contribute to structure and ligand binding
Authors: Cheng Chao‐Sheng , Chen Ming‐Nan , Lai Yen‐Ting , Chen Ting , Lin Ku‐Feng , Liu Yaw‐Jen , Lyu Ping‐Chiang
Published: August 2007

Plant nonspecific lipid transfer protein 2 (nsLTP2) is a small (7 kDa) protein that binds lipid‐like ligands. An inner hydrophobic cavity surrounded by α‐helices is the defining structural feature of nsLTP2. Although nsLTP2 structures have been reported earlier, the detailed mechanisms of ligand binding and lipid transfer remain unclear. In this study, we used site‐directed mutagenesis to determine the role of various hydrophobic residues (L8, I15, F36, F39, Y45, Y48, and V49) in the structure, stability, ligand binding, and lipid transfer activity of rice nsLTP2. Three single mutations (L8A, F36A, and V49A) drastically alter the native tertiary structure and perturb ligand binding and lipid transfer activity. Therefore, these three residues are structurally important. The Y45A mutant, however, retains a native‐like structure but has decreased lipid binding affinity and lipid transfer activity, implying that this aromatic residue is critical for these biological functions. The mutants, I15A and Y48A, exhibit quite different ligand binding affinities. Y48 is involved in planar sterol binding but not linear lysophospholipid association. As for I15A, it had the highest dehydroergosterol binding affinity in spite of the lower lipid binding and transfer abilities. Our results suggest that the long alkyl side chain of I15 would restrict the flexibility of loop I (G13‐A19) for sterol entry. Finally, F39A can markedly increase the exposed hydrophobic surface to maintain its transfer efficiency despite reduced ligand binding affinity. These findings suggest that the residues forming the hydrophobic cavity play various important roles in the structure and function of rice nsLTP2. Proteins 2008. © 2007 Wiley‐Liss, Inc.
Energy minimization in low‐frequency normal modes to efficiently allow for global flexibility during systematic protein–protein docking
Authors: May Andreas , Zacharias Martin
Published: August 2007

Protein–protein association can frequently involve significant backbone conformational changes of the protein partners. A computationally rapid method has been developed that allows to approximately account for global conformational changes during systematic protein–protein docking starting from many thousands of start configurations. The approach employs precalculated collective degrees of freedom as additional variables during protein–protein docking minimization. The global collective degrees of freedom are obtained from normal mode analysis using a Gaussian network model for the protein. Systematic docking searches were performed on 10 test systems that differed in the degree of conformational change associated with complex formation and in the degree of overlap between observed conformational changes and precalculated flexible degrees of freedom. The results indicate that in case of docking searches that minimize the influence of local side chain conformational changes inclusion of global flexibility can significantly improve the agreement of the near‐native docking solutions with the corresponding experimental structures. For docking of unbound protein partners in several cases an improved ranking of near native docking solutions was observed. This was achieved at a very modest (∼2‐fold) increase of computational demands compared to rigid docking. For several test cases the number of docking solutions close to experiment was also significantly enhanced upon inclusion of soft collective degrees of freedom. This result indicates that inclusion of global flexibility can facilitatein silicoprotein–protein association such that a greater number of different start configurations results in favorable complex formation. Proteins 2008. © 2007 Wiley‐Liss, Inc.
Loop modeling: Sampling, filtering, and scoring
Authors: Soto Cinque S. , Fasnacht Marc , Zhu Jiang , Forrest Lucy , Honig Barry
Published: August 2007

We describe a fast and accurate protocol, LoopBuilder, for the prediction of loop conformations in proteins. The procedure includes extensive sampling of backbone conformations, side chain addition, the use of a statistical potential to select a subset of these conformations, and, finally, an energy minimization and ranking with an all‐atom force field. We find that the Direct Tweak algorithm used in the previously developed LOOPY program is successful in generating an ensemble of conformations that on average are closer to the native conformation than those generated by other methods. An important feature of Direct Tweak is that it checks for interactions between the loop and the rest of the protein during the loop closure process. DFIRE is found to be a particularly effective statistical potential that can bias conformation space toward conformations that are close to the native structure. Its application as a filter prior to a full molecular mechanics energy minimization both improves prediction accuracy and offers a significant savings in computer time. Final scoring is based on the OPLS/SBG‐NP force field implemented in the PLOP program. The approach is also shown to be quite successful in predicting loop conformations for cases where the native side chain conformations are assumed to be unknown, suggesting that it will prove effective in real homology modeling applications. Proteins 2008. © 2007 Wiley‐Liss, Inc.
Molecular basis of inhibitory peptide maurotoxin recognizing Kv1.2 channel explored by ZDOCK and molecular dynamic simulations
Authors: Yi Hong , Qiu Su , Cao Zhijian , Wu Yingliang , Li Wenxin
Published: August 2007

Inhibitory peptide‐channel interactions have been utilized to characterize both channels and peptides; however, the fundamental basis for these interactions remains elusive. Here, combined computation methods were employed to study the specific binding of maurotoxin (MTX) peptide to Kv1.2 channel. In the first stage, numerous predicted complexes were generated by docking an ensemble of all 35 NMR conformations of MTX to Kv1.2 channel with ZDOCK program. Then the resulted complexes were clustered and classified into four main binding modes, based on experimental information and interaction energy analysis after the energy minimization and molecular dynamics (MD) simulations. By examining the stability of the plausible candidates through unrestrained MD simulations and calculation of the binding free energies, a final reasonable MTX‐Kv1.2 complex was identified, with an overall high degree of correlation between the calculation and experiment on mutational effects. In the obtained complex structure model, MTX mainly used its β‐sheet domains to associate the channel mouth instead of the well‐recognized functionally important S5P linkers of Kv1.2 channel. Structure analysis characterized that the most essential Tyr32residue of MTX was surrounded by a “pocket” formed by many nonpolar and polar residues of Kv1.2 channel, and revealed a pore‐blocking Lys23and an important Lys7stabilized by strong electrostatic interactions with Asp379of Kv1.2. Furthermore, a stepwise structural arrangement for both ligand and receptor was found to accompany the tighter interaction of MTX into the target channel. The starting conformation of MTX, the side‐chain conformation of the most important residue Tyr32, and proper introduction of flexibility for candidate complexes were demonstrated to be considerably important factors for obtaining the final reasonable complex structure model. All these findings should not only be helpful for identifying more plausible K+channel‐inhibitory peptide complex structures, but also provide intrinsically valuable structural biology information to interpret binding affinities, specificities, and diversity of K+channel‐nature toxin interactions. Proteins 2008. © 2007 Wiley‐Liss, Inc.
Luminescence and laser Raman studies on gamma‐irradiated RbI:Sm3+ crystals
Authors: Manimozhi P. K. , Muralidharan G.
Published: August 2007

This paper reports results of the photoluminescence (PL), thermoluminescence (TL) optical absorption and laser Raman scattering (LRS) studies on RbI:Sm3+ crystals. Sm when doped in the RbI crystals is found to enter in the trivalent state. Interestingly, it is found that the samarium ions act as electron traps and as electron donors as well on gamma irradiation. TL emission studies confirm this interesting be‐havior. The PL spectrum exhibits the characteristic red/orange emission of the Sm ions corresponding to 4G5/2 → 6H9/2 (red) and 4G5/2 → 6H7/2 (orange) transitions. The TL glow indicates that the process is due to two different kinds of traps. Z3 centers are observed on optical treatment and a TL glow peak attributable to them is identified. Aggregation of V centers during the TL process is observed. Laser Raman scattering (LRS) of gamma‐irradiated crystals contains two lines at 111 cm–1 and at 150 cm–1 attributable to I–3 (ions). On prolonged irradiation to γ‐rays, RbI:Sm3+ crystals exhibit a strong line at 180 cm–1, which is attributable to I–5 (ions). TL emission spectra contain the Sm3+ emissions. From PSL and TL emission studies, the TL process is identified to be due to the thermal release of F electrons and their recombination with their counterparts. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Study of molecular dynamics and phase transitions in trimethylammonium trichlorogermanate using 1H NMR and DSC measurements
Authors: Mallikarjunaiah K. J. , Ramesh K. P. , Damle R.
Published: August 2007

(CH3)3NHGeCl3 is prepared, characterized and studied by 1H NMR and differential scanning calorimetry to understand the molecular dynamics and phase transitions. The proton spin lattice relaxation time (T1) is measured at 20.53 MHz in the temperature range 391–5.2 K employing a home‐made pulsed NMR spectrometer. The T1 results show that (CH3)3NHGeCl3 undergoes several phase transitions in the temperature range 391–50 K. Both T1 data and DSC thermograms support the occurrence of phase transitions at 272 K and around 323 K. T1 data are analyzed in three temperature regions using standard models. The T1 variations in the intermediate temperature region 272–100 K are attributed to the hindered reorientations of symmetric groups (CH3 and (CH3)3NH). A broad asymmetric T1 minimum in the temperature region 45–20 K is attributed to quantum rotational tunneling of the methyl groups. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)