bluuebunny/crossref_metadata_2025 huggingface dataset:
Overexpression of S100A2 protein as a prognostic marker for patients with stage I non small cell lung cancer
Authors: Wang Huijun , Zhang Zhengdong , Li Ruiyun , Ang K. Kian , Zhang Huazhong , Caraway Nancy P. , Katz Ruth L. , Jiang Feng
Published: March 2005

S100A2, a calcium‐binding protein, recently became of major interest because of its differential expression during transformation and metastasis in various tumors. The purpose of this study was to investigate the prognostic significance of S100A2 expression in the early‐stage non small lung cancer (NSCLC). Immunohistochemical analysis to determine the percentage of cells staining positive for S100A2 was performed on 11 NSCLC tissue microarray slides containing samples from 113 patients with pathologic stage I NSCLC who had undergone curative surgery. S100A2 was expressed in samples from 79 patients (69.9%). Kaplan‐Meier analysis showed that patients whose tumors had positive S100A2 expression had a significantly lower overall survival and disease‐specific survival rate at 5 years after surgery than did patients with negative S100A2 expression (p < 0.001 and p < 0.001, respectively). Age at diagnosis, histologic type of cancer, degree of differentiation and smoking history did not have a statistically significant effect on survival. Multivariate analysis confirmed that S100A2 expression is a better predictor for disease‐specific survival than were other clinical and histologic variables tested. Our results suggested that the expression of the S100A2 protein in stage I NSCLC indicates poor prognosis and may be used to identify patients with early‐stage NSCLC who might benefit from adjuvant treatment. © 2005 Wiley‐Liss, Inc.
Serum cytochrome c indicates in vivo apoptosis and can serve as a prognostic marker during cancer therapy
Authors: Barczyk Katarzyna , Kreuter Michael , Pryjma Juliusz , Booy Evan P. , Maddika Subbareddy , Ghavami Saeid , Berdel Wolfgang E. , Roth Johannes , Los Marek
Published: March 2005

Despite significant progress in cancer therapy, the outcome of the treatment is often unfavorable. Better treatment monitoring would not only allow an individual more effective, patient‐adjusted therapy, but also it would eliminate some of the side effects. Using a cytochrome c ELISA that was modified to increase sensitivity, we demonstrate that serum cytochrome c is a sensitive apoptotic marker in vivo reflecting therapy‐induced cell death burden. Furthermore, increased serum cytochrome c level is a negative prognostic marker. Cancer patients whose serum cytochrome c level was normal 3 years ago have a twice as high probability to be still alive, as judged from sera samples collected for 3 years, analyzed recently and matched with survival data. Moreover, we show that serum cytochrome c and serum LDH‐activity reflect different stages and different forms of cell death. Cellular cytochrome c release is specific for apoptosis, whereas increased LDH activity is an indicator of (secondary) necrosis. Whereas serum LDH activity reflects the “global” degree of cell death over a period of time, the sensitive cytochrome c‐based method allows confirmation of the individual cancer therapy‐induced and spontaneous cell death events. The combination of cytochrome c with tissue‐specific markers may provide the foundation for precise monitoring of apoptosis in vivo, by “lab‐on‐the‐chip” technology. © 2005 Wiley‐Liss, Inc.
Pharmaceutical‐mediated inactivation of p53 sensitizes U87MG glioma cells to BCNU and temozolomide
Authors: Xu G. Wei , Mymryk Joe S. , Cairncross J. Gregory
Published: March 2005

Pifithrin‐α (PFTα) is a small molecule inhibitor of p53. By reversibly blocking apoptosis in response to DNA damage, PFTα protects normal cells from lethal doses of γ‐radiation (Komarov et al., Science, 1999;285:1733–7). We examined the effect of PFTα on the chemosensitivity of a human cancer in which cell cycle arrest, not apoptosis, is the principle cellular consequence of p53 activation. This was of interest because E6 silencing of p53 sensitizes U87MG astrocytic glioma cells to BCNU and temozolomide (TMZ), cytotoxic drugs that are modestly helpful in the treatment of aggressive astrocytic gliomas. We observed that exposure of U87MG cells to PFTα before cytotoxic chemotherapy attenuated p53‐mediated induction of p21WAF1 protein levels, sensitizing U87MG cells to BCNU and TMZ. Sensitization of U87MG cells was associated with G1 arrest, delayed entry into S‐phase and decreased repair of DNA damage by BCNU. Our findings suggest that in addition to protecting normal cells from the toxic effects of radiation and chemotherapy, small molecule inhibitors of p53, like PFTα, might play a role in clinical oncology by sensitizing certain resistant cancers to cytotoxic chemotherapies. © 2005 Wiley‐Liss, Inc.
A forecast comparison of volatility models: does anything beat a GARCH(1,1)?
Authors: Hansen Peter R. , Lunde Asger
Published: March 2005

We compare 330 ARCH‐type models in terms of their ability to describe the conditional variance. The models are compared out‐of‐sample using DM–$ exchange rate data and IBM return data, where the latter is based on a new data set of realized variance. We find no evidence that a GARCH(1,1) is outperformed by more sophisticated models in our analysis of exchange rates, whereas the GARCH(1,1) is clearly inferior to models that can accommodate a leverage effect in our analysis of IBM returns. The models are compared with the test for superior predictive ability (SPA) and the reality check for data snooping (RC). Our empirical results show that the RC lacks power to an extent that makes it unable to distinguish ‘good’ and ‘bad’ models in our analysis. Copyright © 2005 John Wiley & Sons, Ltd.
Phospholipid polymer surfaces reduce bacteria and leukocyte adhesion under dynamic flow conditions
Authors: Patel Jasmine D. , Iwasaki Yasuhiko , Ishihara Kazuhiko , Anderson James M.
Published: March 2005

Persistence of infection can occur when the host immune response is compromised because of the presence of a foreign implant. Surface modification of biomaterials with phospholipid polymers may enhance biocompatibility and reduce incidence of infection by impeding bacterial and leukocyte adhesion. A rotating disk model, which generates shear stress from 0 to 18 dynes/cm2, was used to characterize adhesion of neutrophils, monocytes, and bacteria in phosphate‐buffered saline (PBS) or 25% human serum on polyethylene terephthalate surfaces coated with a phospholipid polymer, poly[ω‐methacryloyloxyalkyl phosphorylcholine (MAPC)‐co‐n‐butyl methacrylate (BMA)]. The material designated PMB30 contains a methylene chain length, (CH2)n, of n = 2, whereas PMHB30 contains a chain length of n = 6. In PBS, bacterial adhesion was shear stress dependent with the lowest bacterial density observed on PMB30. However, the presence of serum proteins eliminated shear stress and surface chemistry effects in addition to bacterial adhesion reduced to <10% of adhesion in PBS. Trends for leukocyte adhesion in serum demonstrated shear dependence with PMB30 exhibiting the lowest cell density throughout the range of shear stresses. In conclusion, modification of the polyethylene terephthalate surfaces with phospholipid polymers resulted in reduced bacterial and leukocyte adhesion. Furthermore, shortening the methylene chain length of the MAPC copolymer most effectively reduced adhesion. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res 73A: 359–366, 2005
Pexiganan‐incorporated collagen matrices for infected wound‐healing processes in rat
Authors: Gopinath D. , Kumar M. Senthil , Selvaraj D. , Jayakumar R.
Published: March 2005

The use of peptide‐based drugs is limited by their rapid degradability and toxicity at high concentration during their therapeutic application. These problems could be managed by the use of a peptide delivery agent for sustained release in the site of action. Collagen is one of the most proven biomaterials of good biocompatibility with an exceptional ligand encapsulating property. In this work, we have shown that pexiganan, an antimicrobial, 22‐amino‐acid peptide could be incorporated and delivered to the wound‐healing site against bacterial strains Pseudomonas aeruginosa and Staphylococcus aureus. The release profiles of pexiganan collagen films with different collagen concentration were studied. The release of pexiganan from 2.5% w/w of collagen film showed a sustainable activity over 72 h with effective antimicrobial concentrations. Pexiganan‐incorporated collagen (PIC)‐treated groups were compared with open wound (OW)‐ and collagen film (CF)‐treated rats. PIC‐treated animals showed a diminishing level of bacterial growth as compared with OW‐ and CF‐treated animals. The biochemical parameters such as hydroxyproline, protein, DNA, uronic acid, hexosamine, SOD, and catalase content in the granulation tissue of the healing wound revealed increased proliferation of cells involved in tissue reconstruction in PIC‐treated groups when compared with OW‐ and CF‐treated groups. Furthermore, spectroscopic studies suggested that collagen structure is not perturbed by pexiganan incorporation. This study provides rationale for application of collagen membrane for antimicrobial peptide delivery in infected wounds. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res 73A: 320–331, 2005
Effects of amphotericin B on ion transport proteins in airway epithelial cells
Authors: Jornot Lan , Rochat Thierry , Caruso Assunta , Lacroix Jean‐Silvain
Published: March 2005

Topical intranasal application of the antifungal Amphotericin B (AmphoB) has been shown as an effective medical treatment of chronic rhinosinusitis. Because this antibiotic forms channels in lipid membranes, we considered the possibility that it affects the properties and/or cell surface expression of ion channels/pumps, and consequently transepithelial ion transport. Human nasal epithelial cells were exposed apically to AmphoB (50 μM) for 4 h, 5 days (4 h daily), and 4 weeks (4 h daily, 5 days weekly) and allowed to recover for 18–48 h. AmphoB significantly reduced transepithelial potential difference, short‐circuit current, and the amiloride‐sensitive current. This was not due to generalized cellular toxicity as judged from normal transepithelial resistance and mitochondrial activity, but was related to inhibitory effects of AmphoB on ion transport proteins. Thus, cells exposed to AmphoB for 4 h showed decreased apical epithelial sodium channels (ENaC) activity with no change in basolateral Na+K+‐ATPase activity and K+ conductance, and reduced amount of αENaC, α1‐Na+K+‐ATPase, and NKCC1 proteins at the cell membrane, but no change in mRNA levels. After a 5‐day treatment, there was a significant decrease in Na+K+‐ATPase activity. After a 4‐week treatment, a decrease in basolateral K+ conductance and in αENaC and α1‐Na+K+‐ATPase mRNA levels was also observed. These findings may reflect a feedback mechanism aimed to limit cellular Na+ overload and K+ depletion subsequently to formation of AmphoB pores in the cell membrane. Thus, the decreased Na+ absorption induced by AmphoB resulted from reduced cell surface expression of the ENaC, Na+K+‐ATPase pump and NKCC1 and not from direct inhibition of their activities. © 2005 Wiley‐Liss, Inc.
Group III metabotropic glutamate receptor activation inhibits Ca2+ influx and nitric oxide synthase activity in bone marrow stromal cells
Authors: Foreman Megan A. , Gu Yuchun , Howl John D. , Jones Sarah , Publicover Stephen J.
Published: March 2005

Nitric oxide (NO) is pivotal to bone physiology. In the central nervous system constitutive, Ca2+‐calmodulin regulated NO synthase activity and glutamate signalling are intimately linked. Since L‐glutamate signalling occurs in bone and is implicated in bone regulation, we have investigated the effect of L‐glutamate on NO synthase in bone‐derived cells. Treatment of marrow stromal cells with L‐glutamate reduced basal NO synthase activity by 40%. Imaging showed that L‐glutamate caused a rapid, usually localised and slowly‐reversible fall in [Ca2+]i. This effect was resistant to disruption of intracellular Ca2+ stores but sensitive to extracellular La3+ or omission of extracellular Ca2+, demonstrating that glutamate acts by inhibition of membrane Ca2+ influx. The only previous description of such an effect of L‐glutamate is via activation of the group III receptor, mGluR6, in the retina. Using Western blotting and RT‐PCR we detected mGluR6 protein and transcripts in marrow stromal cells. The effects of L‐glutamate on NOS activity and [Ca2+]i in marrow stromal cells were abolished by a group III mGluR inhibitor, (S)‐2‐amino‐2‐methyl‐4‐phosphonobutyric acid. Recording of membrane potential showed that, similarly to the effects of retinal mGluR6 activation, L‐glutamate induced membrane hyperpolarisation (−16 ± 2 mV), which was also sensitive to group III mGluR inhibition. L‐glutamate had no effect on cAMP levels. We conclude that activation of a group III mGluR in bone marrow stromal cells inhibits a Ca2+‐permeable plasma membrane channel, reducing [Ca2+]i and suppressing generation of NO. These observations directly link bone L‐glutamate signalling to processes central to bone growth and regulation. © 2005 Wiley‐Liss, Inc.
Osteoprotegerin (OPG) is localized to the Weibel‐Palade bodies of human vascular endothelial cells and is physically associated with von Willebrand factor
Authors: Zannettino A.C.W. , Holding C.A. , Diamond P. , Atkins G.J. , Kostakis P. , Farrugia A. , Gamble J. , To L.B. , Findlay D.M. , Haynes D.R.
Published: March 2005

Recent studies demonstrate roles for osteoprotegerin (OPG) in both skeletal and extra‐skeletal tissues. Although its role in preventing osteoclast (OC) formation and activity is well documented, emerging evidence suggests a role of OPG in endothelial cell survival and the prevention of arterial calcification. In this communication, we show that vascular endothelial cells in situ, and human umbilical vein endothelial cells (HUVEC) in vitro, express abundant OPG. In HUVEC, OPG co‐localizes with P‐selectin and von Willebrand factor (vWF), within the Weibel‐Palade bodies (WPB). Treatment of HUVEC with the pro‐inflammatory cytokines, tumor necrosis factor (TNF)‐α and IL‐1β, resulted in mobilization from the WPBs and subsequent secretion of OPG protein into the culture supernatant. Furthermore, TNF‐α treatment of HUVEC resulted in a sustained increase in OPG mRNA levels and protein secretion over the 24‐h treatment period. Reciprocal immunoprecipitation experiments revealed that while not associated with P‐Selectin, OPG is physically complexed with vWF both within the WPB and following secretion from endothelial cells. Interestingly, this association was also identified in human peripheral blood plasma. In addition to its interaction with vWF, we show that OPG also binds with high avidity to the vWF reductase, thrombospondin (TSP‐1), raising the intriguing possibility that OPG may provide a link between TSP‐1 and vWF. In summary, the intracellular localization of OPG in HUVEC, in association with vWF, together with its rapid and sustained secretory response to inflammatory stimuli, strongly support a modulatory role in vascular injury, inflammation and hemostasis. © 2005 Wiley‐Liss, Inc.
Cooperation between antioxidants and 1,25‐dihydroxyvitamin D3 in induction of leukemia HL60 cell differentiation through the JNK/AP‐1/Egr‐1 pathway
Authors: Wang Qing , Salman Hagar , Danilenko Michael , Studzinski George P.
Published: March 2005

Vitamin D derivatives have demonstrated anti‐cancer activity, but their clinical use is precluded by hypercalcemia. Previously, we found that carnosic acid potentiates differentiation of human leukemia cells induced by low concentrations of 1alpha,25‐dihydroxyvitamin D3 (1,25D3). In this study, we investigated if this effect is a general property of antioxidants, and whether there is a common mechanism whereby antioxidants potentiate monocytic differentiation. We found that all antioxidants tested enhanced differentiation‐related cell cycle arrest induced by a low (1 nM) concentration of 1,25D3. Addition of antioxidants to 1,25D3 activated the JNK pathway as indicated by increased phosphorylation of c‐jun and ATF‐2, although each compound alone had a minimal effect. Antioxidants also enhanced the 1,25D3‐induced AP‐1 DNA binding and transactivation ability. Expression of Egr‐1 and c‐fos was increased by combinations of antioxidants and 1,25D3, in parallel with the activation of the JNK pathway. The potentiation of differentiation by antioxidants was inhibited by JNK inhibitor SP600125 and a dominant negative JNK 1/2 construct, and Egr‐1 and c‐fos expression was proportionally decreased, suggesting that JNK pathway regulates these transcription factors. While potentiating the prodifferentiation effect of 1,25D3, antioxidants did not promote the elevation of basal levels of intracellular calcium by 1,25D3. The results indicate that JNK‐AP1 pathway has an important role in the potentiation of 1,25D3‐induced differentiation by antioxidants, and regulates expression of Egr‐1 and c‐fos. Combinations of antioxidants with 1,25D3 should be further evaluated for use in cancer chemoprevention and therapy. © 2005 Wiley‐Liss, Inc.
Nowhere zero 4‐flow in regular matroids
Authors: Lai Hong‐Jian , Li Xiangwen , Poon Hoifung
Published: March 2005

Jensen and Toft 8 conjectured that every 2‐edge‐connected graph without a K5‐minor has a nowhere zero 4‐flow. Walton and Welsh 19 proved that if a coloopless regular matroid M does not have a minor in {M(K3,3), M*(K5)}, then M admits a nowhere zero 4‐flow. In this note, we prove that if a coloopless regular matroid M does not have a minor in {M(K5), M*(K5)}, then M admits a nowhere zero 4‐flow. Our result implies the Jensen and Toft conjecture. © 2005 Wiley Periodicals, Inc. J Graph Theory
Late Pleistocene Palaeoenvironments of the Southern Lake Agassiz Basin, USA
Authors: Yansa Catherine H. , Ashworth Allan C.
Published: March 2005

Macroscopic plant remains, pollen, insect and mollusc fossils recovered from a cut bank on the Red River in North Dakota, USA, provide evidence that an extensive wetland occupied the southern basin of Lake Agassiz from 10 230 to 9900 14C yr BP. Marsh‐dwelling plants and invertebrates had colonised the surface of a prograding delta during the low‐water Moorhead Phase of Lake Agassiz. A species of Salix (willow) was abundant along distributary channels, and stands of Populus tremuloides (aspen), Ulmus sp. (elm), Betula sp. (birch), and Picea sp. (spruce) grew on the better‐drained sand bars and beach ridges. Most of the species of plants, insects, and molluscs represented as fossils are within their existing geographic ranges. Based on a few species with more northerly distributions, mean summer temperature may have been about 1–2°C lower than the present day. No change in species composition occurred in the transition from the Younger Dryas to Preboreal. At the time that the wetland existed, Lake Agassiz was draining either eastward to the North Atlantic Ocean or northwestward to the Arctic Ocean. The wetland was drowned during the Emerson Phase transgression that resulted in meltwater draining southward to the Gulf of Mexico after 9900 14C yr BP. Copyright © 2005 John Wiley & Sons, Ltd.
An earth systems approach to understanding the tectonic and cultural landscapes of linked marine embayments: Avon‐Heathcote Estuary (Ihutai) and Lake Ellesmere (Waihora), New Zealand
Authors: McFadgen Bruce G. , Goff James R.
Published: March 2005

An earth systems study of the Avon‐Heathcote Estuary (Ihutai), New Zealand, shows that tectonic activity has a marked direct and indirect control upon its geomorphology and human settlement in the area. We discuss the Late Holocene history of the embayment in relation to large earthquakes and their after‐effects. Of particular note is the rapid fluvial transfer of sand to the coast causing dune formation and a more delayed pulse of coarser sediment causing channel avulsion of the Waimakariri River. While dune system development seems to occur soon after tectonic activity, river channel avulsion, spit/barrier formation and ongoing geomorphological changes may well relate to periods of tectonic activity that occurred 100–200 years previously. The interaction between these two sediment delivery systems causes significant, and often rapid, changes to coastal geomorphology and ecosystems that have serious implications for human populations living at or near the coast. We show a more region‐wide picture of the direct and indirect effects of tectonic activity, by comparing two embayments that represent coastal points of entry at opposite ends of the Waimakariri River floodplain: the Avon‐Heathcote Estuary (Ihutai) and Lake Ellesmere (Waihora). Copyright © 2005 John Wiley & Sons, Ltd.
Volcanic ash layers from the Last Glacial Termination in the NGRIP ice core
Authors: Mortensen Anette K. , Bigler Matthias , Grönvold Karl , Steffensen Jørgen P. , Johnsen Sigfús J.
Published: March 2005

The tephrochronological record of the 1400–1640 m depth (∼10 000–16 000 calendar ice core years before present) of the NGRIP ice core has been established by particle screening of selected samples. Ash was identified in 20 samples. Correlation with ice, marine and terrestrial records from volcanic source regions in the northern hemisphere positively identifies the Saksunarvatn Ash and the Vedde Ash (Ash Zone 1). Major element chemistry of the remaining identified ash layers mainly points towards an Icelandic origin. This tephrochronological record provides new important marker horizons for correlating the timing of the climatic changes associated with the Last Glacial Termination within the North Atlantic region, as well as outlining more details concerning the frequency and composition of volcanic eruptions occurring at this deglaciation. Copyright © 2005 John Wiley & Sons, Ltd.
Pleistocene geochronologies for fluvial sedimentary sequences: an archaeologist's perspective
Authors: Hosfield R. T. , Chambers J. C.
Published: March 2005

Current models of Pleistocene fluvial system development and dynamics are assessed from the perspective of European Lower and Middle Palaeolithic stone tool assemblages recovered from fluvial secondary contexts. Fluvial activity is reviewed both in terms of Milankovitch‐scale processes across the glacial/interglacial cycles of the Middle and Late Pleistocene, and in response to sub‐Milankovitch scale, high‐frequency, low‐magnitude climatic oscillations. The chronological magnitude of individual phases of fluvial activity is explored in terms of radiocarbon‐dated sequences from the Late Glacial and early Holocene periods.

It is apparent that fluvial activity is associated with periods of climatic transition, both high and low magnitude, although system response is far more universal in the case of the high magnitude glacial/interglacial transitions. Current geochronological tools do not permit the development of high‐resolution sequences for Middle Pleistocene sediments, while localised erosion and variable system responses do not facilitate direct comparison with the ice core records. However, Late Glacial and early Holocene sequences indicate that individual fluvial activity phases are relatively brief in duration (e.g. 102 and 103 yr). From an archaeological perspective, secondary context assemblages can only be interpreted in terms of a floating geochronology, although the data also permit a reinvestigation of the problems of artefact reworking. Copyright © 2005 John Wiley & Sons, Ltd.
Two-phonon resonant hyper-Raman scattering treatment in a CdS
crystal
Authors: Semenova L E , Prokhorov K A
Published: March 2005

A theoretical treatment for the hyper-Raman scattering
(HRS) by 2LO phonons in CdS is presented when incident frequency
is near the two-photon resonance with excitonic states. The cross
section for the two-phonon HRS as a function of the photon energy
of exciting radiation is calculated.
Getting it together: The leadership challenge of mergers and acquisitions
Authors: Stahl Günter K.
Published: March 2005

Mergers, acquisitions, and strategic alliances are supposed to create new, stronger organizations, but history shows that such combinations often fall far short of expectations. Cross‐border integrations, such as those between Western and Eastern companies, are particularly difficult to manage. Here the CEOs of two multinational firms that have been there talk about the factors that set winning corporate combinations apart from the rest.
Personal bonds: Whether serving rich or poor, trust is the key
Authors: Jenkins Joyce
Published: March 2005

Comparing the views of leaders in two major financial institutions in Asia—one serving the very rich, the other the very poor—it seems that despite hugely different client bases, they have many more issues in common than one might think.
Three‐Dimensionally Ordered Macroporous Syndiotactic Polystyrene: Preparation and Characterization
Authors: Yan Weidong , Li Haiqing , Shen Xiaoli
Published: March 2005

Summary: Three‐dimensionally ordered macroporous (3DOM) syndiotactic polystyrenes with pore size in the range of 71–286 nm were fabricated by means of silica templates using (dbm)2Ti(OPh)2/MAO catalytic system. The resulting materials were characterized by NMR, SEM, powder X‐ray diffraction, GPC and DSC. The results indicated that the 3DOM syndiotactic polystyrenes were highly syndiotactic, and the pore contraction increased when the average pore diameter decreased. Compared with bulk syndiotactic polystyrenes, 3DOM syndiotactic polystyrene possessed lower molecular weight, narrower molecular weight distribution, and lower crystallinity and melting temperature.

SEM image of 3DOM syndiotactic polystyrene, the inset shows the detail of the cavities.

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SEM image of 3DOM syndiotactic polystyrene, the inset shows the detail of the cavities.
Formaldehyde‐Free Wood Adhesives from Decayed Wood
Authors: Li Kaichang , Geng Xinglian
Published: March 2005

Summary: Extensive studies using mussel adhesive protein as a formaldehyde‐free, strong, and water‐resistant adhesive model revealed that a combination of a polymer with catechol moieties and a polymer with amino groups could serve as a strong and water‐resistant wood adhesive. This study demonstrated that the treatment of abundant and readily available brown‐rot‐fungus‐decayed wood with NaBH4 followed by mixing with polyethylenimine resulted in a formaldehyde‐free, strong, and water‐resistant wood adhesive.

Lignin is demethylated by brown‐rot fungi and then reduced using NaBH4.

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Lignin is demethylated by brown‐rot fungi and then reduced using NaBH4.
Chiral Crystal Structure of Racemic Binaphthyl Poly(ether ketone) Macrocycles
Authors: Wang Xing , Liu Na , Cao Hui , Liu Wei , Chen Chunhai , Zhang Wanjin , Wei Yen
Published: March 2005

Summary: The crystal structure of rigid, hollow, racemic binaphthyl poly(ether ketone) macrocycles has been elucidated by single crystal X‐ray analysis. Multitudinal interactions were identified within the chiral space group P212121. The structural analysis revealed that this macrocyclic compound contains an elliptic chiral cavity with a size of 9.80 × 5.18 Å, which is similar to that of cyclodextrins. The knowledge about the interaction sites and the structure of the binaphthyl‐based macrocycle provides a unique opportunity to understand its molecular or chiral recognition properties.

Space‐filling representation of the single (R)‐macrocycle.

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Space‐filling representation of the single (R)‐macrocycle.
Solid‐State 1H NMR Studies of Degradable Poly(ethylene oxide) Based Hydrogels
Authors: Naraghi Kaynoush , Meurer Bernard , Lutz Pierre J.
Published: March 2005

Summary: Hydrogels, the elastic chains of which are constituted of a short central poly(1,3‐dioxolane) (PDXL) block surrounded by two hydrophilic poly(ethylene oxide) (PEO) blocks, were obtained by free radical homopolymerization of α,ω–methacryloyloxy PEO‐block‐1,3‐PDXL‐block‐PEO macromonomers. The central PDXL block is known to be sensitive to acidic degradation due to the presence of acetal groups. Once swollen to equilibrium, these hydrogels were characterized for their equilibrium swelling degree and their mechanical properties and network degradation studies were carried out.

Representation proposed for the breaking of a PEO‐block‐PDXL‐block‐PEO block copolymer.

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Representation proposed for the breaking of a PEO‐block‐PDXL‐block‐PEO block copolymer.
Cover Picture: Macromol. Theory Simul. 3/2005
Authors: Chaffey‐Millar Hugh , Busch Markus , Davis Thomas P. , Stenzel Martina H. , Barner‐Kowollik Christopher
Published: March 2005

Cover: The picture shows an abstract and generic star polymer with six arms, produced via the RAFT process. This is overlayed with the main equation relating to the statistical convolution of arm MWDs to form star MWDs. On top of this is a simulated MWD from stars with varying numbers of arms. Further details can be found in the Full Paper by H. Chaffey‐Millar, M. Busch, M. H. Stenzel, T. P. Davis, and C. Barner‐Kowollik* on page 143.
E1A‐F is overexpressed early in human colorectal neoplasia and associated with cyclooxygenase‐2 and matrix metalloproteinase‐7
Authors: Boedefeld William M. , Soong Richie , Weiss Heidi , Diasio Robert B. , Urist Marshall M. , Bland Kirby I. , Heslin Martin J.
Published: March 2005

Studies suggest the expression of cyclooxygenase‐2 (COX‐2) and matrilysin (MMP‐7) increase in the early stages of colorectal carcinogenesis, however their interaction with other molecular markers is poorly understood. Results from cell line studies and mouse models suggest polyomavirus enhancer activator 3 (PEA3) may play a role in the activation of COX‐2 and MMP‐7 promoters. However, the role of E1A‐F, the human homolog of murine PEA3, in colorectal cancer (CRC) development has not been elucidated. In this study, we used real‐time reverse transcription (RT)‐polymerase chain reaction (PCR) to measure the levels of E1A‐F, COX‐2, and MMP‐7 in matched normal mucosa, adenomas, and/or carcinomas from 128 patients. Our results demonstrate significant overexpression of E1A‐F and MMP‐7 in adenomas and E1A‐F, COX‐2, and MMP‐7 in carcinomas. In carcinomas, E1A‐F expression was significantly associated with both COX‐2 and MMP‐7 overexpression. These results suggest E1A‐F is overexpressed in early stages of human CRC development and may be an important factor in the overexpression of COX‐2 and MMP‐7. © 2005 Wiley‐Liss, Inc.
Ka‐band 1‐W PHEMT MMIC power amplifiers on 2mil‐thick GaAs substrates
Authors: Huang C. W. , Chang S. J. , Wu W. , Wu C. L. , Chang C. S.
Published: March 2005

A fully matched Ka‐band wideband pseudomorphic high‐electron‐mobility transistor (PHEMT) 1‐W monolithic millimeter‐wave integrated circuit (MMIC) high‐power amplifier (HPA) without any external circuit is developed. The two‐stage HPAs are prepared on 2‐mil GaAs substrates with a small chip size of 3.46 × 2.9 mm. At least 10‐dB small‐signal gain, 29.5 dBmP−1dB, 31‐dBmPsat, and better than 12‐dB output return loss. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 45: 181–185, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20764
Convergence of Gaussian‐beam modes in corrugated conical horns
Authors: Martín‐Jiménez F. , García E. , O'Sullivan C. , De Haro L. , López Fernández J. A. , Tercero F. , Sierra‐Castañer M. , Martín‐Pintado J.
Published: March 2005

Gaussian beam‐mode expansion with only the fundamental mode does not work properly when the angular region of interest is wide. It is necessary to use higher‐order mode for the expansion. A study of the convergence of these higher order modes is presented for the case of a corrugated conical horn. Conclusions about the number of modes necessary for good accuracy are given. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 45: 199–203, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20769
Contrast‐enhanced MRI with new biodegradable macromolecular Gd(III) complexes in tumor‐bearing mice
Authors: Zong Yuda , Wang Xinghe , Goodrich K. Craig , Mohs Aaron M. , Parker Dennis L. , Lu Zheng‐Rong
Published: March 2005

The structures of polydisulfide‐based biodegradable macromolecular Gd(III) complexes were modified to improve their in vivo retention time and MRI contrast enhancement. Steric hindrance was introduced around the disulfide bonds to control their access to free thiols in order to alter the degradation rate of the copolymers. Two new macromolecular agents, (Gd‐DTPA)‐cystine copolymers (GDCP) and (Gd‐DTPA)‐cystine diethyl ester copolymers (GDCEP), were prepared. Both agents were readily degraded in vitro and in vivo by the disulfide‐thiol exchange reaction, but at a slow rate. The introduction of COOH and COOEt groups slowed down the degradation of the copolymers in the incubation with 15 μM cysteine. Metabolic degradation products were identified by matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF) mass spectrometry in the urine samples from rats injected with the agents. The T1 relaxivity (r1) was 5.43 mM−1s−1 for GDCP, and 5.86 mM−1s−1 for GDCEP, respectively, at 3T. MRI contrast enhancement of both agents was studied in nude mice bearing MDA‐BM‐231 human breast carcinoma xenografts, on a Siemens Trio 3T scanner. The modified agents resulted in more significant contrast enhancement in the blood pool and tumor periphery than (Gd‐DTPA)‐cystamine copolymers (GDCC) and a low‐molecular‐weight control agent, Gd‐(DTPA‐BMA), at a dose of 0.1 mmol‐Gd/kg. The results demonstrate that the structural modification of the biodegradable macromolecular Gd(III) complexes resulted in a relatively slow degradation of the macromolecules and significantly improved in vivo contrast enhancement. The modified agents show promise for use in investigations of blood pool and cancer by contrast‐enhanced (CE) MRI. Magn Reson Med 53:835–842, 2005. © 2005 Wiley‐Liss, Inc.
Magnetic resonance imaging of inflammation with a specific selectin‐targeted contrast agent
Authors: Boutry Sébastien , Burtea Carmen , Laurent Sophie , Toubeau Gérard , Vander Elst Luce , Muller Robert N.
Published: March 2005

E‐selectin‐targeted contrast enhancement of blood vessels in inflamed tissues was investigated with a new contrast agent, Gd‐DTPA‐B(sLex)A, which was recently obtained by grafting a synthetic mimetic of sialyl‐Lewisx, an E‐selectin ligand, onto Gd‐DTPA. The pharmacokinetics, biodistribution, and potential to image inflammation by MRI of this E‐selectin‐targeted contrast agent were evaluated. The inhibition (by 15–34%) produced by Gd‐DTPA‐B(sLex)A on Sialyl Lex‐PAA‐biotin binding to E‐selectin confirmed the specific interaction of the new contrast agent with this adhesion molecule. Gd‐DTPA‐B(sLex)A was tested at a dose of 0.1 mmol/kg b.w. on mice and rats in a fulminant hepatitis model induced by the co‐administration of D‐galactosamine and E. coli lipopolysaccharide. A significant and prolonged contrast enhancement between blood vessels and liver parenchyma was obtained in pathological conditions, which attests to the specificity of the agent for E‐selectin. The prolonged vascular residence (48.9 min in hepatitis vs. 29.8 min in healthy animals), as evidenced by the pharmacokinetic characterization, suggests that Gd‐DTPA‐B(sLex)A interacts with the specific receptors expressed during inflammation. The biodistribution of the compound indicates its retention in inflamed liver by both specific mechanisms and nonspecific accumulation due to the necrotic lesions. The same mechanisms are invoked to account for its retention in the spleen. Magn Reson Med 53:800–807, 2005. © 2005 Wiley‐Liss, Inc.
Numerical solution of the Bloch equations provides insights into the optimum design of PARACEST agents for MRI
Authors: Woessner Donald E. , Zhang Shanrong , Merritt Matthew E. , Sherry A. Dean
Published: March 2005

Paramagnetic lanthanide complexes that display unusually slow water exchange between an inner sphere coordination site and bulk water may serve as a new class of MRI contrast agents with the use of chemical exchange saturation transfer (CEST) techniques. To aid in the design of paramagnetic CEST agents for reporting important biological indices in MRI measurements, we formulated a theoretical framework based on the modified Bloch equations that relates the chemical properties of a CEST agent (e.g., water exchange rates and bound water chemical shifts) and various NMR parameters (e.g., relaxation rates and applied B1 field) to the measured CEST effect. Numerical solutions of this formulation for complex exchanging systems were readily obtained without algebraic manipulation or simplification. For paramagnetic CEST agents of the type used here, the CEST effect is relatively insensitive to the bound proton relaxation times, but requires a sufficiently large applied B1 field to highly saturate the Ln3+‐bound water protons. This in turn requires paramagnetic complexes with large Ln3+‐bound water chemical shifts to avoid direct excitation of the exchanging bulk water protons. Although increasing the exchange rate of the bound protons enhances the CEST effect, this also causes exchange broadening and increases the B1 required for saturation. For a given B1, there is an optimal exchange rate that results in a maximal CEST effect. This numerical approach, which was formulated for a three‐pool case, was incorporated into a MATLAB nonlinear least‐square optimization routine, and the results were in excellent agreement with experimental Z‐spectra obtained with an aqueous solution of a paramagnetic CEST agent containing two different types of bound protons (bound water and amide protons). Magn Reson Med 53:790–799, 2005. © 2005 Wiley‐Liss, Inc.
Addressing efficiency and residual magnetization cross talk in multi‐slice 2D steady‐state free precession imaging of the heart
Authors: Slavin Glenn S. , Rettmann Dan W.
Published: March 2005

This work presents an efficient method for achieving steady state in multi‐slice 2D balanced steady‐state free precession (SSFP) imaging of cardiac function. With current techniques, data acquisition for each slice is preceded by one or two heartbeats of dummy excitations. Depending on the number of heartbeats required for data acquisition, these dummy heartbeats can represent a large fraction of the total imaging time. As described here, FIESTA‐SP (FIESTA with steady‐state preparation) increases the imaging efficiency to nearly 100% by eliminating dummy heartbeats. Steady state for each slice is achieved using a linear flip angle series of excitations during the first cardiac phase of the first heartbeat for each slice. Because imaging proceeds immediately from one slice to the next, a heretofore‐unseen issue arises where residual magnetization from each slice contaminates subsequent acquisitions. Accelerating the approach to steady state for each slice and eliminating slice cross talk are important for both multi‐slice and interactive real‐time imaging. Magn Reson Med 53:965–969, 2005. © 2005 Wiley‐Liss, Inc.
Generalized scalar measures for diffusion MRI using trace, variance, and entropy
Authors: Özarslan Evren , Vemuri Baba C. , Mareci Thomas H.
Published: March 2005

This paper details the derivation of rotationally invariant scalar measures from higher‐rank diffusion tensors (DTs) and functions defined on a unit sphere. This was accomplished with the use of an expression that generalizes the evaluation of the trace operator to tensors of arbitrary rank, and even to functions whose domains are the unit sphere. It is shown that the mean diffusivity is invariant to the selection of tensor rank for the model used. However, this rank invariance does not apply to the anisotropy measures. Therefore, a variance‐based, general anisotropy measure is proposed. Also an information theoretical parametrization of anisotropy is introduced that is frequently more consistent with the meaning attributed to anisotropy. We accomplished this by associating anisotropy with the amount of orientational information present in the data, regardless of the imaging technique used. Using a simplified model of fibrous tissue, we simulated anisotropy values with varying orientational complexity and tensor models. Simulations suggested that a lower‐rank tensor model may produce artificially low anisotropy values in voxels with complex structure. This was confirmed with a spin‐echo experiment performed on an excised rat brain. Magn Reson Med 53:866–876, 2005. © 2005 Wiley‐Liss, Inc.
Real‐time magnetic resonance with physiologic monitoring for improved scan localization
Authors: Stainsby Jeffrey A. , Sussman Marshall S. , Flexman Molly L. , Wright Graham A.
Published: March 2005

Imaging of the coronary arteries at diagnostic resolutions is made difficult due to cardiac and respiratory motion during data acquisition. Cardiac gating and respiratory gating or breath holding are effective ways to reduce the effects of motion. The optimal cardiac and respiratory timings vary widely across individuals. This work presents a real‐time magnetic resonance imaging approach with physiologic monitoring that can be used to predict the optimal timings on a subject‐by‐subject basis during a brief real‐time prescan. The feasibility of this approach at determining the optimal cardiac trigger delay and respiratory phase is demonstrated. Magn Reson Med 53:954–959, 2005. © 2005 Wiley‐Liss, Inc.
Mathematical framework for simulating diffusion tensor MR neural fiber bundles
Authors: Leemans A. , Sijbers J. , Verhoye M. , Van der Linden A. , Van Dyck D.
Published: March 2005

White matter (WM) fiber tractography (i.e., the reconstruction of the 3D architecture of WM fiber pathways) is known to be an important application of diffusion tensor magnetic resonance imaging (DT‐MRI). For the quantitative evaluation of several fiber‐tracking properties, such as accuracy, noise sensitivity, and robustness, synthetic ground‐truth DT‐MRI data are required. Moreover, an accurate simulated phantom is also required for optimization of the user‐defined tractography parameters, and objective comparisons between fiber‐tracking algorithms. Therefore, in this study a mathematical framework for simulating DT‐MRI data, based on the physical properties of WM fiber bundles, is presented. We obtained a model of a WM fiber bundle by parameterizing the various features that characterize this bundle. We then evaluated three different synthetic DT‐MRI models using experimental data in order to test the proposed methodology, and to determine the optimum model and parameter settings for constructing a realistic simulated DT‐MRI phantom. Several examples of how the mathematical framework can be applied to compare fiber‐tracking algorithms are presented. Magn Reson Med 53:944–953, 2005. © 2005 Wiley‐Liss, Inc.
Flip angle calculation for consistent contrast in spoiled gradient echo imaging
Authors: Busse Reed F.
Published: March 2005

In spoiled gradient echo sequences, the T1‐weighting of image contrast is strongly affected by a nonlinear interaction of two sequence parameters, repetition time (TR) and flip angle (α). If α is not properly adjusted to compensate for variation in TR due to changing resolution, bandwidth, or number of slices, any optimization of contrast‐to‐noise may be compromised. Currently, there is no direct way to compare or reproduce the contrast properties of one sequence to another with a different TR. Here, it is demonstrated that for short TRs α may be calculated and automatically adjusted such that relative contrast—the shape of the signal‐versus‐T1 curve—remains consistent and signal scales proportionally to √TR in all tissues. TR is then free to vary to accommodate a range of sequence parameters without impacting relative contrast and the T1‐weighting of one sequence can be compared to, or reproduced in, another study with a different TR. Magn Reson Med 53:977–980, 2005. © 2005 Wiley‐Liss, Inc.
Exchange‐influenced T2ρ contrast in human brain images measured with adiabatic radio frequency pulses
Authors: Michaeli Shalom , Gröhn Heidi , Gröhn Olli , Sorce Dennis J. , Kauppinen Risto , Springer Charles S. , Uğurbil Kâmil , Garwood Michael
Published: March 2005

Transverse relaxation in the rotating frame (T2ρ) is the dominant relaxation mechanism during an adiabatic Carr–Purcell (CP) spin‐echo pulse sequence when no delays are used between pulses in the CP train. The exchange‐induced and dipolar interaction contributions (T2ρ,ex and T2ρ,dd) depend on the modulation functions of the adiabatic pulses used. In this work adiabatic pulses having different modulation functions were utilized to generate T2ρ contrast in images of the human occipital lobe at magnetic field of 4 T. T2ρ time constants were measured using an adiabatic CP pulse sequence followed by an imaging readout. For these measurements, adiabatic full passage pulses of the hyperbolic secant HSn (n = 1 or 4) family having significantly different amplitude—and frequency—modulation functions were used with no time delays between pulses. A dynamic averaging (DA) mechanism (e.g., chemical exchange and diffusion in the locally different magnetic susceptibilities) alone was insufficient to fully describe differences in brain tissue water proton T2ρ time constants. Measurements of the apparent relaxation time constants (T) of brain tissue water as a function of the time between centers of pulses (τcp) at 4 and 7 T permitted separation of the DA contribution from that of dipolar relaxation. The methods presented assess T2ρ relaxation influenced by DA in tissue and provide a means to generate T2ρ contrast in MRI. Magn Reson Med 53:823–829, 2005. © 2005 Wiley‐Liss, Inc.
Dynamic autocalibrated parallel imaging using temporal GRAPPA (TGRAPPA)
Authors: Breuer Felix A. , Kellman Peter , Griswold Mark A. , Jakob Peter M.
Published: March 2005

Current parallel imaging techniques for accelerated imaging require a fully encoded reference data set to estimate the spatial coil sensitivity information needed for reconstruction. In dynamic parallel imaging a time‐interleaved acquisition scheme can be used, which eliminates the need for separately acquiring additional reference data, since the signal from directly adjacent time frames can be merged to build a set of fully encoded full‐resolution reference data for coil calibration. In this work, we demonstrate that a time‐interleaved sampling scheme, in combination with autocalibrated GRAPPA (referred to as TGRAPPA), allows one to easily update the coil weights for the GRAPPA algorithm dynamically, thereby improving the acquisition efficiency. This method may update coil sensitivity estimates frame by frame, thereby tracking changes in relative coil sensitivities that may occur during the data acquisition. Magn Reson Med 53:981–985, 2005. Published 2005 Wiley‐Liss, Inc.
Variability of metabolite yield using STEAM or PRESS sequences in vivo at 3.0 T, illustrated with myo‐inositol
Authors: Kim Hyeonjin , Thompson Richard B. , Hanstock Christopher C. , Allen Peter S.
Published: March 2005

Using as an example the myo‐inositol (mI) band at ∼3.6 ppm in the proton spectrum from brain, an evaluation is presented that highlights the difficulties of quantifying metabolites with strongly coupled spins with either STEAM or PRESS and demonstrates some advantages of prospective sequence analysis when measuring their concentrations. The analysis emphasizes the variation in coupled‐spin signal yield and lineshape, compared with that of uncoupled singlets such as N‐acetylaspartate, a variation that differs from one metabolite spin system to another. This difference in variation between a target metabolite (e.g., mI) and its contaminating background metabolites (e.g., glutamate and taurine, etc.) is shown to provide in certain circumstances a substantial reduction in background contamination (both metabolite and macromolecule) while maintaining sufficient signal‐to‐noise ratio for precise quantification. For example, sequence times are demonstrated, both for STEAM and for PRESS, that, relative to the short echo‐time sequences typical in the literature, enhance the signal to metabolite background of the 3.6‐ppm band of mI by factors of 1.7 and 1.3, respectively, essentially eliminate the macromolecular baseline, and yet in vivo retain an S/N ∼ 10 in both cases. Magn Reson Med 53:760–769, 2005. © 2005 Wiley‐Liss, Inc.