bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fabrication and Characterization of Nanostructured and Thermosensitive Polymer Membranes for Wound Healing and Cell Grafting
Authors: Wang L.‐S. , Chow P.‐Y. , Phan T.‐T. , Lim I. J. , Yang Y.‐Y. 
Published: May 2006

AbstractNanostructured, transparent, and thermosensitive membranes synthesized by bicontinuous microemulsion polymerization of N‐isopropylacrylamide (NIPAAm), methyl methacrylate (MMA), and 2‐hydroxyethyl methacrylate (HEMA) using a polymerizable nonionic surfactant, ω‐methoxy poly(ethylene oxide)40 undecyl α‐methacrylate macromonomer have recently been reported. In this study, the synthesis and characterization of membranes with various compositions are presented in detail, focusing on the effects of environmental temperature and membrane composition on surface hydrophilicity, cell attachment, and detachment. The membranes synthesized with differing compositions have a nanoporous structure, and are transparent and thermosensitive in their swelling ratio and cell‐attachment characteristics. Decreasing the environmental temperature and the MMA content leads to an increase in the wettability of the membrane surface. In addition, both L929 murine neoplastic fibroblasts and primary human dermal fibroblasts can attach to and detach from the membranes with varying temperature. High cell‐attachment and ‐detachment efficiencies are achieved by optimizing membrane composition and environmental temperature. In addition, the membranes do not show significant cytotoxicity. These membranes have great potential for the construction of a new generation of dressings and cell‐delivery systems for wound healing.
Preparation, characteristics, and flocculation behavior of modified palygorskite–polyacrylamide ionic hybrids
Authors: Wang Meng , Qian Jinwen , Zheng Baoqing , Yang Wuyuan 
Published: May 2006

AbstractA novel inorganic–organic hybrid with modified palygorskite (MPGS) and acrylamide was prepared with a heterogeneous redox initiator system composed of a reductive agent (MPGS) together with an oxidant (Ce4+). The MPGS–polyacrylamide (PAM) hybrids were characterized by X‐ray diffraction, 1H‐NMR, Fourier transform infrared spectroscopy, conductometry, viscometry, and size exclusion chromatography. The MPGS–PAM hybrid could be a starlike and ionic bond hybrid. The ionization behavior of the MPGS–PAM hybrid in deionized water depended strongly on its coil dimension and the palygorskite content in the hybrid. The flocculation performance of the MPGS–PAM hybrid in a kaolin suspension was also related to its intrinsic viscosity and the palygorskite content and was better than that of PAM, except for that of the MPGS–PAM hybrid with a high palygorskite content. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1494–1500, 2006
β‐lactoglobulin as a potential modulator of intestinal activity and morphology in neonatal piglets
Authors: Sutton Leonard F. , Alston‐Mills Brenda 
Published: May 2006

AbstractStudies were conducted to determine the effects of the whey protein β‐lactoglobulin (blg) on the intestinal development and intestinal morphology in neonatal piglets. Two trials (5 and 28 days) were conducted on piglets in three separate groups. One group served as a control group while the remaining two were experimental groups based on diets. The two experimental diets were a bovine colostrum powder, one with supplementation with blg and the other without. The control group remained suckling on a sow. All groups were weaned on day 20 and placed onto a solid commercial piglet diet. Enzymatic activity, total DNA synthesis, crypt depth, and villus height were all parameters used to evaluate the effect of blg. Piglets fed a diet supplement with blg had the greatest total DNA after 5 days. Sow‐reared piglets had the greatest intestinal morphology development with regards to villus height. No significant differences were found in enzymatic activity between treatments. Anat Rec Part A 288A:601–608, 2006. © 2006 Wiley‐Liss, Inc.
Effects of growth rate on cell extract performance in cell‐free protein synthesis
Authors: Zawada James , Swartz James 
Published: May 2006

AbstractCell‐free protein synthesis is a useful research tool and now stands poised to compete with in vivo expression for commercial production of proteins. However, both the extract preparation and protein synthesis procedures must be scaled up. A key challenge is producing the required amount of biomass that also results in highly active cell‐free extracts. In this work, we show that the growth rate of the culture dramatically affects extract performance. Extracts prepared from cultures with a specific growth rate of 0.7/h or higher produced approximately 0.9 mg/mL of chloramphenicol acetyl transferase (CAT) in a batch reaction. In contrast, when the source culture growth rate was 0.3/h, the resulting extract produced only 0.5 mg/mL CAT. Examination of the ribosome content in the extracts revealed that the growth rate of the source cells strongly influenced the final ribosome concentration. Polysome analysis of cell‐free protein synthesis reactions indicated that about 22% of the total 70S ribosomes are in polysomes for all extracts regardless of growth rate. Furthermore, the overall specific production from the 70S ribosomes is about 22 CAT proteins per ribosome over the course of the reaction in all cases. It appears that rapid culture growth rates are essential for producing a productive extract. However, growth rate does not seem to influence specific ribosome activity. Rather, the increase in extract productivity is a result of a higher ribosome concentration. These results are important for cell‐free technology and also suggest an assay for intrinsic in vivo protein synthesis activity. © 2006 Wiley Periodicals, Inc.
Sequencing batch membrane biofilm reactor for simultaneous nitrogen and phosphorus removal: Novel application of membrane‐aerated biofilm
Authors: Terada Akihiko , Yamamoto Tetsuya , Tsuneda Satoshi , Hirata Akira 
Published: May 2006

AbstractA sequencing batch membrane biofilm reactor (SBMBfR) was developed for simultaneous carbon, nitrogen, and phosphorus removal from wastewater. This reactor was composed of two functional parts: (1) a gas‐permeable membrane on which a nitrifying biofilm formed and (2) a bulk solution in which bacteria, mainly denitrifying polyphosphate‐accumulating organisms (DNPAOs), were suspended. The reactor was operated sequentially under anaerobic condition and then under membrane aeration condition in one cycle. During the anaerobic period, organic carbon was consumed by DNPAOs; this was accompanied by phosphate release. During the subsequent membrane aeration period, nitrifying bacteria utilized oxygen supplied directly to them from the inside of the membrane. Consequently, the nitrite and nitrate products diffused into the bulk solution, where they were used by DNPAOs as electron acceptors for phosphate uptake. In a long‐term sequencing batch operation, the mean removal efficiencies of total organic carbon (TOC), total nitrogen (T‐N), and total phosphorus (T‐P) under steady‐state condition were 99%, 96%, and 90%, respectively. In addition, fluorescence in situ hybridization (FISH) clearly demonstrated the difference in bacterial community structure between the membrane biofilm and the suspended sludge: ammonia‐oxidizing bacteria belonging to the Nitrosomonas group were dominant in the region adjacent to the membrane throughout the operation, and the occupation ratio of the well‐known polyphosphate‐accumulating organism (PAO) Candidatus “Accumulibacter phosphates” in the suspended sludge gradually increased to a maximum of 37%. © 2006 Wiley Periodicals, Inc.
Intermolecular Insertion of an N,N‐Heterocyclic Carbene into a Nonacidic CH Bond: Kinetics, Mechanism and Catalysis by (K‐HMDS)2 (HMDS=Hexamethyldisilazide)
Authors: Lloyd‐Jones Guy C. , Alder Roger W. , Owen‐Smith Gareth J. J. 
Published: May 2006

AbstractThe reaction of 2‐[13C]‐1‐ethyl‐3‐isopropyl‐3,4,5,6‐tetrahydropyrimidin‐1‐ium hexafluorophosphate ([13C1]‐1‐PF6) with a slight excess (1.03 equiv) of dimeric potassium hexamethyldisilazide (“(K‐HMDS)2”) in toluene generates 2‐[13C]‐3‐ethyl‐1‐isopropyl‐3,4,5,6‐tetrahydropyrimid‐2‐ylidene ([13C1]‐2). The hindered meta‐stable N,N‐heterocyclic carbene [13C1]‐2 thus generated undergoes a slow but quantitative reaction with toluene (the solvent) to generate the aminal 2‐[13C]‐2‐benzyl‐3‐ethyl‐1‐isopropylhexahydropyrimidine ([13C1]‐14) through formal CH insertion of C(2) (the “carbene carbon”) at the toluene methyl group. Despite a significant pKa mismatch (ΔpKa 1+ and toluene estimated to be ca. 16 in DMSO) the reaction shows all the characteristics of a deprotonation mechanism, the reaction rate being strongly dependent on the toluene para substituent (ρ=4.8(±0.3)), and displaying substantial and rate‐limiting primary (kH/kD=4.2(±0.6)) and secondary (kH/kD=1.18(±0.08)) kinetic isotope effects on the deuteration of the toluene methyl group. The reaction is catalysed by K‐HMDS, but proceeds without cross over between toluene methyl protons and does not involve an HMDS anion acting as base to generate a benzyl anion. Detailed analysis of the reaction kinetics/kinetic isotope effects demonstrates that a pseudo‐first‐order decay in 2 arises from a first‐order dependence on 2, a first‐order dependence on toluene (in large excess) and, in the catalytic manifold, a complex noninteger dependence on the K‐HMDS dimer. The rate is not satisfactorily predicted by equations based on the Brønsted salt‐effect catalysis law. However, the rate can be satisfactorily predicted by a mole‐fraction‐weighted net rate constant: −d[2]/dt=({x2 kuncat}+{(1−x2) kcat})[2]1[toluene]1, in which x2 is determined by a standard bimolecular complexation equilibrium term. The association constant (Ka) for rapid equilibrium–complexation of 2 with (K‐HMDS)2 to form [2(K‐HMDS)2] is extracted by nonlinear regression of the 13C NMR shift of C(2) in [13C1]‐2 versus [(K‐HMDS)2] yielding: Ka=62(±7) M−1; δC(2) in 2=237.0 ppm; δC(2) in [2(K‐HMDS)2]=226.8 ppm. It is thus concluded that there is discrete, albeit inefficient, molecular catalysis through the 1:1 carbene/(K‐HMDS)2 complex [2(K‐HMDS)2], which is found to react with toluene more rapidly than free 2 by a factor of 3.4 (=kcat/kuncat). The greater reactivity of the complex [2(K‐HMDS)2] over the free carbene (2) may arise from local Brønsted salt‐effect catalysis by the (K‐HMDS)2 liberated in the solvent cage upon reaction with toluene.
Structural information from quadrupolar nuclei in solid state NMR
Authors: Ashbrook Sharon E. , Duer Melinda J. 
Published: May 2006

AbstractSolid‐state NMR has become the method of choice for determining details of molecular‐level structure in heterogeneous systems. Though spin‐1/2 nuclei still form the core of most such studies, quadrupolar nuclei are increasingly being used. This review assesses what is currently possible, from achieving high‐resolution spectra for quadrupolar nuclei (a prerequisite for most structure determination work), to forming correlation spectra which give qualitative details of spatial proximity of nuclei and the determination of internuclear distances, between quadrupolar spins and quadrupolar and spin‐1/2 nuclei. Examples are given of each method discussed, and the advantages and disadvantages of the various experiments for different possible applications are assessed. © 2006 Wiley Periodicals, Inc. Concepts Magn Reson Part A 28A: 183–248, 2006.
Characterization of melanocyte‐specific inducible Cre recombinase transgenic mice
Authors: Bosenberg Marcus , Muthusamy Viswanathan , Curley David P. , Wang Zhenxiong , Hobbs Cara , Nelson Betsy , Nogueira Cristina , Horner James W. , DePinho Ronald , Chin Lynda 
Published: May 2006

AbstractConditional Cre‐mediated recombination has emerged as a robust method of introducing somatic genetic alterations in an organ‐specific manner in the mouse. Here, we generated and characterized mice harboring a 4‐hydroxytamoxifen (OHT)‐inducible Cre recombinase‐estrogen receptor fusion transgene under the control of the melanocyte‐specific tyrosinase promoter, designated Tyr::CreERT2. Cre‐mediated recombination was induced in melanocytes in a spatially and temporally controlled manner upon administration of OHT and was documented in embryonic melanoblasts, follicular bulb melanocytes, dermal dendritic melanocytes, epidermal melanocytes of tail skin, and in putative melanocyte stem cells located within the follicular bulge. Functional evidence suggestive of recombination in follicular melanocyte stem cells included the presence of Cre‐mediated recombination in follicular bulb melanocytes 1 year after topical OHT administration, by which time several hair cycles have elapsed and the melanocytes residing in this location have undergone multiple rounds of apoptosis and replenishment. These Tyr:: CreERT2 transgenic mice represent a useful resource for the evaluation of melanocyte developmental genetics, the characterization of melanocyte stem cell function and dynamics, and the construction of refined mouse models of malignant melanoma. genesis 44:262–267, 2006. Published 2006 Wiley‐Liss, Inc.
Cancer progression by non‐clonal chromosome aberrations
Authors: Heng Henry H.Q. , Bremer Steven W. , Stevens Joshua , Ye Karen J. , Miller Fred , Liu Gou , Ye Christine J. 
Published: May 2006

AbstractThe establishment of the correct conceptual framework is vital to any scientific discipline including cancer research. Influenced by hematologic cancer studies, the current cancer concept focuses on the stepwise patterns of progression as defined by specific recurrent genetic aberrations. This concept has faced a tough challenge as the majority of cancer cases follow non‐linear patterns and display stochastic progression. In light of the recent discovery that genomic instability is directly linked to stochastic non‐clonal chromosome aberrations (NCCAs), and that cancer progression can be characterized as a dynamic relationship between NCCAs and recurrent clonal chromosome aberrations (CCAs), we propose that the dynamics of NCCAs is a key element for karyotypic evolution in solid tumors. To support this viewpoint, we briefly discuss various basic elements responsible for cancer initiation and progression within an evolutionary context. We argue that even though stochastic changes can be detected at various levels of genetic organization, such as at the gene level and epigenetic level, it is primarily detected at the chromosomal or genome level. Thus, NCCA‐mediated genomic variation plays a dominant role in cancer progression. To further illustrate the involvement of NCCA/CCA cycles in the pattern of cancer evolution, four cancer evolutionary models have been proposed based on the comparative analysis of karyotype patterns of various types of cancer. J. Cell. Biochem. © 2006 Wiley‐Liss, Inc.
Biological significance and development of practical synthesis of biotin
Authors: Seki Masahiko 
Published: May 2006

AbstractBiotin (1), a water‐soluble B series vitamin, distributes widely in microorganisms, plants, and animals. Biosynthesis of 1 involves five steps sequence starting from pimelic acid. The last step, a transformation from dethiobiotin (DTB) to 1, includes an iron clusters‐mediated radical process. The compound 1 is a cofactor of carboxylation enzymes and plays crucial roles in the metabolism of fatty acids, sugars, and α‐amino acids. In addition to the increasing application to feed additives, recent reports have revealed that 1 enhances insulin secretion in animals, suggesting it for a promising therapeutic candidate for an anti‐diabetes drug. The remarkably strong affinity of 1 with avidin and streptavidin has been extensively applied for such technologies as photoaffinity labeling. Among the number of approaches to 1 so far developed in 50 years, a synthesis using L‐cysteine and thiolactone as a starting material and a key intermediate, respectively, represents one of the best routes leading to 1, because of short steps, high yield, use of inexpensive reagents, and ease of operation. © 2006 Wiley Periodicals, Inc. Med Res Rev, 26, No. 4, 434–482, 2006
Lipid signal extraction by SLIM: Application to 1H MR spectroscopic imaging of human calf muscles
Authors: Dong Zhengchao , Hwang Jong‐Hee 
Published: May 2006

AbstractThe measurement of intramyocellular lipid (IMCL) using in vivo 1H MRS is important for better understanding muscle physiology. However, the accurate measurement of IMCL in muscle adjacent to subcutaneous fat (SF) and bone marrow (BM) is often hampered by contaminations from the fat. In this article a new postacquisition processing method is proposed that selectively removes unwanted lipid signals based on the spectral localization by imaging (SLIM) technique, which can localize spectra from arbitrarily shaped regions. The effectiveness of this lipid extraction method is demonstrated by both computer simulation and in vivo experiments in the human calf. The advantage of this method is that unwanted lipid signal, such as SF signal, can be selectively and completely removed. After the contaminating fat signals are removed, the quality of muscle spectra adjacent to SF improves such that it becomes comparable to that in uncontaminated muscle regions in 1H MRSI of the calf. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
Supportive employment for individuals with chronic schizophrenia: the case for a National Health Service community‐based sheltered workshop
Authors: Creegan Shelagh , Williams Fiona L.R. 
Published: May 2006

AbstractA pilot project was established from 1992 to 1994 to provide people with chronic schizophrenia living in Dundee, Scotland, with a National Health Service sheltered workshop that would be fully integrated into the local business community. Of the 43 clients who attended the sheltered workshop, 38 agreed to take part in the project. Typical attenders were single, middle‐aged men with schizophrenia. Twenty‐five per cent had spent more than two years in hospital; 75% had been unemployed for more than five years. The clients' use of National Health Service day facilities more than halved while attending the workshop. Their hospital readmission rates were low (16%) compared with the local readmission rates for people with schizophrenia in Dundee (86%). A training approach based on the general principles of social skills training contributed to positive vocational outcomes for one‐third of the workshop clients.The findings suggest that the onus of responsibility for providing work for many individuals with schizophrenia remains with the National Health Service, and in particular, occupational therapy. Occupational therapy staff must assess their clients effectively and provide quality training leading to opportunities for paid employment. These results have implications for the training of occupational therapy staff and also for the staffing structure in sheltered workshops. Copyright © 1997 Whurr Publishers Ltd.
A qualitative study of amlodipine and its related compounds by electrospray ionization tandem mass spectrometry
Authors: Gibbons John , Pugh Jonathan , Dimopoulos‐Italiano Gina , Pike Richard 
Published: May 2006

AbstractA comprehensive structural analysis of amlodipine and certain related compounds was performed by electrospray ionization tandem mass spectrometry. Triple quadrupole and quadrupole time‐of‐flight instruments were used to provide collision‐induced dissociation and accurate mass measurement for selected product and second‐generation product ions. A unique ion rearrangement was observed, which was found to be characteristic of certain dihydropyridines. This study provides a fundamental understanding of the fragmentation of these compounds. The structural elucidation of an unknown impurity is presented as an example. Copyright © 2006 John Wiley & Sons, Ltd.
Identification of isocephalomannine in the presence of cephalomannine isomers and alkali metal ion adducts in a paclitaxel active pharmaceutical ingredient using electrospray tandem mass spectrometry
Authors: Vivekanandan Kannan , Swamy Madugundu Guru , Prasad Sudhanand , Mukherjee Rama , Burman Anand C. 
Published: May 2006

AbstractA strategy is developed for the identification of isocephalomannine in the presence of alkali metal ion adducts and other cephalomannine isomers in a paclitaxel active pharmaceutical ingredient. Intact molecular ion analyses and a sub‐structural study have been performed for the differentiation of isocephalomannine (2‐debenzoylpaclitaxel‐2‐pentenoate) from cephalomannine and 7‐epi‐cephalomannine. A comparative study of the cephalomannine isomers was carried out using molecular ions (MS) and fragmentation patterns (MS/MS) for sub‐structural analysis. An attempt has been made to identify isocephalomannine in Cremophor® EL formulations. Copyright © 2006 John Wiley & Sons, Ltd.
Ionic liquid matrices with phosphoric acid as matrix additive for the facilitated analysis of phosphopeptides by matrix‐assisted laser desorption/ionization mass spectrometry
Authors: Tholey Andreas 
Published: May 2006

AbstractMatrix‐assisted laser desorption/ionization mass spectrometry (MALDI‐MS) is a powerful tool for the analysis and characterization of protein phosphorylation on the peptide level. In this study, the applicability of ionic liquid matrices (ILM) formed by combination of the crystalline MALDI matrix 2,5‐dihydroxybenzoic acid (DHB) with pyridine or n‐butylamine was tested for the analysis of phosphopeptides. Low ionization efficiency in both positive and negative ion mode was observed in acid‐free sample preparations. Upon addition of 0.1% trifluoroacetic acid (TFA), ion formation was increased, but analogously to the situation described earlier for pure DHB, best results were obtained upon use of 1% phosphoric acid as matrix additive. The samples prepared in this way were significantly more homogeneous than preparations with pure DHB, thus avoiding the need for time‐consuming search for hot spots. Other characteristics like metastable fragmentation of phosphopeptides did not differ from that observed in classical preparations. The limits of detection for synthetic phosphopeptides and singly or multiply phosphorylated peptides from tryptic digests of α‐ and β‐casein were comparable with those obtained when using pure DHB; in some cases even higher signal intensities could be observed in the ILM. The use of ILM in combination with 1% phosphoric acid as matrix additive significantly facilitates analysis of phosphopeptides by MALDI‐MS. Copyright © 2006 John Wiley & Sons, Ltd.
The crystal structure of Mycobacterium tuberculosis adenylate kinase in complex with two molecules of ADP and Mg2+ supports an associative mechanism for phosphoryl transfer
Authors: Bellinzoni Marco , Haouz Ahmed , Graña Martin , Munier‐Lehmann Hélène , Shepard William , Alzari Pedro M. 
Published: May 2006

AbstractThe crystal structure of Mycobacterium tuberculosis adenylate kinase (MtAK) in complex with two ADP molecules and Mg2+ has been determined at 1.9 Å resolution. Comparison with the solution structure of the enzyme, obtained in the absence of substrates, shows significant conformational changes of the LID and NMP‐binding domains upon substrate binding. The ternary complex represents the state of the enzyme at the start of the backward reaction (ATP synthesis). The structure is consistent with a direct nucleophilic attack of a terminal oxygen from the acceptor ADP molecule on the β‐phosphate from the donor substrate, and both the geometry and the distribution of positive charge in the active site support the hypothesis of an associative mechanism for phosphoryl transfer.