bluuebunny/crossref_metadata_2025_split huggingface dataset:
cis‐trans Peptide‐Bond Isomerization in α‐Methylproline Derivatives
Authors: Torbeev Vladimir Y. , Fumi Erik , Ebert Marc‐Olivier , Schweizer W. Bernd , Hilvert Donald 
Published: December 2012

Abstractα‐Methyl‐L‐proline is an α‐substituted analog of proline that has been previously employed to constrain prolyl peptide bonds in a trans conformation. Here, we revisit the cis‐trans prolyl peptide bond equilibrium in derivatives of α‐methyl‐L‐proline, such as N‐Boc‐protected α‐methyl‐L‐proline and the hexapeptide H‐Ala‐Tyr‐αMePro‐Tyr‐Asp‐Val‐OH. In Boc‐α‐methyl‐L‐proline, we found that both cis and trans conformers were populated, whereas, in the short peptide, only the trans conformer was detected. The energy barrier for the cis‐trans isomerization in Boc‐α‐methyl‐L‐proline was determined by line‐shape analysis of NMR spectra obtained at different temperatures and found to be 1.24 kcal/mol (at 298 K) higher than the corresponding value for Boc‐L‐proline. These findings further illuminate the conformationally constraining properties of α‐methyl‐L‐proline.
Ring‐Extended Gramicidin S Analogs Containing cis δ‐Sugar Amino Acid Turn Mimetics with Varying Ring Size
Authors: Knijnenburg Annemiek D. , Spalburg Emile , de Neeling Albert J. , Mars‐Groenendijk Roos H. , Noort Daan , Grotenbreg Gijsbert M. , van der Marel Gijs A. , Overkleeft Herman S. , Overhand Mark 
Published: December 2012

AbstractThis article presents a series of ring‐extended gramicidin S derivatives, 9–14, that have four ornithine residues as polar protonated side chains and one modified turn region containing a mono‐functionalized cis‐δ‐oxetane, δ‐furanoid, or δ‐pyranoid sugar amino acid residue. Of the GS analogs evaluated, we identified compound 7, which contains the mono‐benzyloxy cis‐δ‐pyranoid sugar amino acid, as having a better biological profile than the clinically applied topical antibiotic gramicidin S.
A Study on the Diastereoselective Synthesis of α‐Fluorinated β3‐Amino Acids by α‐Fluorination
Authors: Peddie Victoria , Abell Andrew D. 
Published: December 2012

AbstractThe treatment of a β3‐amino acid methyl ester with 2.2 equiv. of lithium diisopropylamide (LDA), followed by reaction with 5 equiv. of N‐fluorobenzenesulfonimide (NFSI) at −78° for 2.5 h and then 2 h at 0°, gives syn‐fluorination with high diastereoisomeric excess (de). The de and yield in these reactions are somewhat influenced by both the size of the amino acid side chain and the nature of the amine protecting group. In particular, fluorination of N‐Boc‐protected β3‐homophenylalanine, β3‐homoleucine, β3‐homovaline, and β3‐homoalanine methyl esters, 5 and 9–11, respectively, all proceeded with high de (>86% of the syn‐isomer). However, fluorination of N‐Boc‐protected β3‐homophenylglycine methyl ester (16) occurred with a significantly reduced de. The use of a Cbz or Bz amine‐protecting group (see 3 and 15) did not improve the de of fluorination. However, an N‐Ac protecting group (see 17) gave a reduced de of 26%. Thus, a large N‐protecting group should be employed in order to maximize selectivity for the syn‐isomer in these fluorination reactions.
Minimally Competent Lewis Acid Catalysts: Indium(III) and Bismuth(III) Salts Produce Rhamnosides (=6‐Deoxymannosides) in High Yield and Purity
Authors: Coss Clifford , Carrocci Tucker , Maier Raina M. , Pemberton Jeanne E. , Polt Robin 
Published: December 2012

AbstractGlycosylation of decan‐1‐ol (2), (±)‐decan‐2‐ol (3), and (±)‐methyl 3‐hydroxydecanoate (4) with L‐rhamnose peracetate 5 to produce rhamnosides (=6‐deoxymannosides) 6, 7, and 8 in the presence of Lewis acids BF3⋅Et2O, Sc(OTf)3, InBr3, and Bi(OTf)3 was studied (Table 1). While the strong Lewis acids BF3⋅Et2O and Sc(OTf)3 were effective as glycosylation promoters, they had to be used in excess; however, glycosylation required careful control of reaction times and temperatures, and these Lewis acids produced impurities in addition to the desired glycosides. Enantiomerically pure rhamnosides (R)‐1 and (S)‐1 (Fig.) were obtained from L‐rhamnose peracetate 5 and (±)‐benzyl 3‐hydroxydecanoate (9) via the diastereoisomeric rhamnosides 10 (Table 2; Scheme 3). The much weaker Lewis acids InBr3 and Bi(OTfl)3 produced purer products in high yield under a wider range of conditions (higher temperatures), and were effective glycosylation promoters even when used catalytically (<10% catalyst; Table 2). We refer to these Lewis acids as ‘minimally competent Lewis acids’ (cf. Scheme 4).
Design and Synthesis of Nucleoproline Amino Acids for the Straightforward Preparation of Chiral and Conformationally Constrained Nucleopeptides
Authors: Kramer Rolf A. , Bleicher Konrad H. , Wennemers Helma 
Published: December 2012

AbstractA straightforward synthesis of orthogonally protected nucleoproline (Nup) amino acids and their coupling to oligomers are described. A key step is the attachment of alkynylated nucleobases to Fmoc‐protected 4‐azidoproline (Fmoc‐Azp‐OH) by a Cu‐catalyzed 1,3‐dipolar cycloaddition (‘click reaction’). The developed protocol allows preparation of the nucleoprolines in scales of >30 g. Solid‐phase peptide synthesis proved to be straightforward with these Nup amino acids. The resulting oligonucleoproline peptides adopt defined helices, are very well H2O soluble, and show comparable cell‐penetrating properties as recently reported α‐nucleoalanine peptides.
Biochemically and topographically engineered poly(ethylene glycol) diacrylate hydrogels with biomimetic characteristics as substrates for human corneal epithelial cells
Authors: Yañez‐Soto B. , Liliensiek S. J. , Murphy C. J. , Nealey P. F. 
Published: December 2012

AbstractIncorporation of biophysical and biochemical cues into the design of biomaterials is an important strategy for tissue engineering, the design of biomedical implants and cell culture. Hydrogels synthesized from poly(ethylene glycol) diacrylate (PEGDA) were investigated as a platform to simultaneously present human corneal epithelial cells (HCECs)in vitrowith topography and adhesion peptides to mimic the native physical and chemical attributes of the basement membrane underlying the epitheliumin vivo. Hydrogels synthesized from aqueous solutions of 20% PEGDA (Mw= 3400 g/mol) prevented nonspecific cell adhesion and were functionalized with the integrin‐binding peptide Arg‐Gly‐Asp (RGD) in concentrations from 5 to 20 mM. The hydrogels swelled minimally after curing and were molded with ridge and groove features with lateral dimensions from 200 to 2000 nm and 300‐nm depth. HCECs were cultured on topographic surfaces functionalized with RGD and compared with control unfunctionalized topographic substrates. HCEC alignment, either parallel or perpendicular to ridges, was influenced by the culture media on substrates promoting nonspecific attachment. In contrast, the alignment of HCECs cultured on RGD hydrogels showed substantially less dependence on the culture media. In the latter case, the moldable RGD‐functionalized hydrogels allowed for decoupling the cues from surface chemistry, soluble factors, and topography that simultaneously impact HCEC behavior. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2013.
Cell–material interactions on biphasic polyurethane matrix
Authors: Dicesare Patrick , Fox Wade M. , Hill Michael J. , Krishnan G. Rajesh , Yang Shuying , Sarkar Debanjan 
Published: December 2012

AbstractCell–matrix interaction is a key regulator for controlling stem cell fate in regenerative tissue engineering. These interactions are induced and controlled by the nanoscale features of extracellular matrix and are mimicked on synthetic matrices to control cell structure and functions. Recent studies have shown that nanostructured matrices can modulate stem cell behavior and exert specific role in tissue regeneration. In this study, we have demonstrated that nanostructured phase morphology of synthetic matrix can control adhesion, proliferation, organization and migration of human mesenchymal stem cells (MSCs). Nanostructured biodegradable polyurethanes (PU) with segmental composition exhibit biphasic morphology at nanoscale dimensions and can control cellular features of MSCs. Biodegradable PU with polyester soft segment and hard segment composed of aliphatic diisocyanates and dipeptide chain extender were designed to examine the effect polyurethane phase morphology. By altering the polyurethane composition, morphological architecture of PU was modulated and its effect was examined on MSC. Results show that MSCs can sense the nanoscale morphology of biphasic polyurethane matrix to exhibit distinct cellular features and, thus, signifies the relevance of matrix phase morphology. The role of nanostructured phases of a synthetic matrix in controlling cell–matrix interaction provides important insights for regulation of cell behavior on synthetic matrix and, therefore, is an important tool for engineering tissue regeneration. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2013.
Influence of processing parameters on microstructure and biocompatibility of surface laser sintered hydroxyapatite–SiO2 composites
Authors: Kivitz E. , Görke R. , Schilling A. F. , Zhang J. , Heinrich J. G. 
Published: December 2012

AbstractSilica‐doped hydroxyapatite (HA) is a promising material concerning biocompatibility to natural bone, bioactivity and osteoconductive characteristics. HA exhibits phase transformations during sintering which are attendant to the change in volume and thermal strain. To avoid cracks during sintering, the exact knowledge of the phase transition temperatures is necessary. The sintering behavior of HA can be improved by adding amorphous silica with a low coefficient of thermal expansion. Therefore, the phase transformations in the system HA–SiO2 were analyzed by using differential scanning calorimetry followed by quantitative phase analysis by X‐ray diffraction with the Riedveld method. The maximum sintering temperature without reversible phase transformation was defined as 1265°C. In laser surface sintered (LSS) samples, amorphous SiO2, HA, and Si‐α‐TCP (or α‐TCP) were detected. By comparison, only crystalline phases, such as cristobalite, HA, β‐TCP, and Si‐α‐TCP (or α‐TCP), were determined after furnace sintering. Scanning electron microscopy micrographs of furnace sintered and LSS samples show the differences in the resulting microstructures. Biocompatibility was determined by measuring cell activity of osteoblasts cultivated on four laser‐sintered materials in the HA–SiO2 system in comparison to normal cell culture plastic. Cell proliferation was similar on all surfaces. The level of the cell activity on day 8 varied depending on the composition of the material and increased linearly as the amorphous SiO2 content rose. Taken together a laser‐based method to develop novel biocompatible HA–SiO2 ceramics with adjustable properties and possible applications as orthopedic bioceramics are discussed. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2013.
Starved for Credit? Bank Lending Strategies and Constraints
Authors: Sagner James S. 
Published: December 2012

AbstractMergers and acquisitions (M&As) often require financing and bank loans. But the problem that corporations face in obtaining loans hasn't been much relieved in the years since the 2008 credit crisis. The author of this article, a financial consultant, reports that clients are constantly complaining about the difficulty in obtaining financing. And many clients blame the banks for their plight. This article discusses the complex issues impacting this situation and strategies that corporate treasurers can take to cope with the problem. © 2013 Wiley Periodicals, Inc.
U.S. Firms: Still Too Much Cash?
Authors: Marcum Bill , Martin Dale R. , Strickland Deon 
Published: December 2012

AbstractU.S. firms have been accumulating cash fairly steadily since the 1980s. Has this changed four years after the “official” end of the recession? And are both large and small firms continuing to retain cash? © 2013 Wiley Periodicals, Inc.
Auditing Treasury Operations: Risks and Traps
Authors: Nogler George , Jang Inwon 
Published: December 2012

AbstractAuditing a company's treasury operations can now be a maze of risks and traps. For a small company, a treasury audit may be as simple as verifying the cash balances. But today's increasingly complex global financial environment produces many challenges for the auditor. The authors discuss the situation and suggest how auditors can better cope with it. © 2013 Wiley Periodicals, Inc.
Repeated subrupture overload causes progression of nanoscaled discrete plasticity damage in tendon collagen fibrils
Authors: Veres Samuel P. , Harrison Julia M. , Lee J. Michael 
Published: December 2012

AbstractA critical feature of tendons and ligaments is their ability to resist rupture when overloaded, resulting in strains or sprains instead of ruptures. To treat these injuries more effectively, it is necessary to understand how overload affects the primary load‐bearing elements of these tissues: collagen fibrils. We have investigated how repeated subrupture overload alters the collagen of tendons at the nanoscale. Using scanning electron microscopy to examine fibril morphology and hydrothermal isometric tension testing to look at molecular stability, we demonstrated that tendon collagen undergoes a progressive cascade of discrete plasticity damage when repeatedly overloaded. With successive overload cycles, fibrils develop an increasing number of kinks along their length. These kinks—discrete zones of plastic deformation known to contain denatured collagen molecules—are accompanied by a progressive and eventual total loss ofD‐banding along the surface of fibrils, indicating a loss of native molecular packing and further molecular denaturation. Thermal analysis of molecular stability showed that the destabilization of collagen molecules within fibrils is strongly related to the amount of strain energy dissipated by the tendon after yielding during tensile overload. These novel findings raise new questions about load transmission within tendons and their fibrils and about the interplay between crosslinking, strain‐energy dissipation ability, and molecular denaturation within these structures. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31: 731–737, 2013
Biomechanical and rheological characterization of mild intervertebral disc degeneration in a large animal model
Authors: Detiger Suzanne E.L. , Hoogendoorn Roel J.W. , van der Veen Albert J. , van Royen Barend J. , Helder Marco N. , Koenderink Gijsje H. , Smit Theo H. 
Published: December 2012

AbstractBiomechanical properties of healthy and degenerated nucleus pulposus (NP) are thought to be important for future regenerative strategies for intervertebral disc (IVD) repair. However, which properties are pivotal as design criteria when developing NP replacement materials is ill understood. Therefore, we determined and compared segmental biomechanics and NP viscoelastic properties in normal and mildly degenerated discs. In eight goats, three lumbar IVDs were chemically degenerated using chondroitinase ABC (CABC), confirmed with radiography and MRI after euthanasia 12 weeks post‐operative. Neutral zone (NZ) stiffness and range of motion (ROM) were determined sagitally, laterally, and rotationally for each spinal motion segment (SMS) using a mechanical testing device. NPs were isolated for oscillatory shear experiments; elastic and viscous shear moduli followed from the ratio between shear stress and strain. Water content was quantified by weighing before and after freeze‐drying. Disc height on radiographs and signal intensity on MRI decreased (6% and 22%, respectively, p < 0.01) after CABC treatment, confirming that chemical degeneration provides a good model of disc degeneration. Furthermore, CABC‐injected IVDs had significantly lower NZ stiffness and larger ROM in lateral bending (LB) and axial rotation (AR) than controls. Rheometry consistently revealed significantly lower (10–12%) viscoelastic moduli after mild degeneration within goats, though the inter‐animal differences were relatively large (complex modulus ∼12 to 41 kPa). Relative water content in the NP was unaffected by CABC, remaining at ∼75%. These observations suggest that viscoelastic properties have a marginal influence on mechanical behavior of the whole SMS. Therefore, when developing replacement materials the focus should be on other design criteria, such as biochemical cues and swelling pressure. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31: 703–709, 2013
Tonsilloplasty versus tonsillectomy in children with sleep‐disordered breathing: Short‐ and long‐term outcomes
Authors: Chaidas Konstantinos S. , Kaditis Athanasios G. , Papadakis Chariton E. , Papandreou Nikolaos , Koltsidopoulos Petros , Skoulakis Charalampos E. 
Published: December 2012

Objectives/HypothesisAdenoidectomy and tonsillectomy (TE) is the standard treatment for obstructive sleep‐disordered breathing (SDB) in children with adenotonsillar hypertrophy. Tonsilloplasty (TP) is a new surgical technique that includes partial TE. The purpose of this study was to assess the short‐ and long‐term outcomes of TP compared to TE.Study DesignA comparison study.MethodsChildren with SDB and tonsillar hypertrophy underwent TP or TE. The two groups were compared regarding immediate postoperative course and long‐term effects.ResultsFifty‐one children (age, 6.3 ± 2.5 years) underwent TE, and 50 children (age, 5.9 ± 2.1 years) had TP. The TP group had significantly less intraoperative bleeding compared to the TE group (25.6 ± 8.2 vs. 38.3 ± 12.3 mL, P < .001). Subjects with TP were pain free earlier than children with TE (4.5 ± 0.4 vs. 7.7 ± 0.4 days, P < .001) and returned to a normal diet sooner (3.8 ± 0.2 vs. 7.1 ± 0.3 days, P < .001). By the 3rd to 4th postoperative night, upper airway obstruction was relieved in all participants. Six years postoperatively, 48 of 51 children in the TE group and 43 of 50 children in the TP group participated in a telephone survey. No significant differences were found between the two groups regarding the frequency of recurrent snoring (30.2% in TP vs. 25% in TE), apneas (4.7% vs. 0%), and upper airway infections per year (P > .05).ConclusionsTP is an alternative surgical method for treatment of SDB related to tonsillar hypertrophy with favorable postoperative course and comparable long‐term results.Level of Evidence2c.
Differential proteomics identifies PDIA3 as a novel chemoprevention target in human colon cancer cells
Authors: Ménoret Antoine , Drew David A. , Miyamoto Shingo , Nakanishi Masako , Vella Anthony T. , Rosenberg Daniel W. 
Published: December 2012

AbstractChemoprevention offers a promising strategy to prevent or delay the development of various cancers. Critical to this approach is the identification of molecular targets that may track with chemopreventive efficacy. To address this issue, we screened a panel of chemoprevention agents, including resveratrol, epigallocatechin‐3‐gallate, ursodeoxycholic acid, and sulindac sulfide for their effects on human colon cancer cell viability. Resveratrol elicited the most potent effect in HCT116 cells and was selected for further study. Proteomic PF 2D maps were generated from HCT116 cells treated with resveratrol versus vehicle alone. Analysis of proteomic maps using tandem mass spectrometry (MS) identified a panel of differentially modified proteins. Two proteins, actin and Hsp60, were previously shown in other cell culture systems to be affected by resveratrol, validating our approach. PDIA3, RPL19, histone H2B and TCP1β were uniquely identified by our proteomic discovery platform. PDIA3 was of particular interest given its potential role in regulating chemosensitivity of cancer cells. Total levels of PDIA3 in HCT116 cells were unchanged following 24 h of resveratrol treatment, confirmed by Western blot analysis. Immunoprecipitation of PDIA3 revealed a new set of client proteins following resveratrol treatment, including α, β, and δ‐catenins, and cellular fractionation identified decreased nuclear localization of α‐catenin by resveratrol. These data establish differential proteomic mapping as a powerful tool for identifying novel molecular targets of chemopreventive agents. © 2012 Wiley Periodicals, Inc.
Reconstruction of large composite buccal defects using single soft tissue flap—analysis of functional outcome
Authors: Kekatpure Vikram D. , Manjula B.V. , Mathias Smita , Trivedi Nirav P. , Selvam Sumithra , Kuriakose Moni Abraham 
Published: December 2012

AbstractResection of advanced gingivo‐buccal tumors results in a posterolateral mandibular and large soft tissue defect. Because of large soft tissue requirement, these defects are difficult to reconstruct using a single osteocutaneous flap. A double free flap reconstruction of such defects is recommended. However, double flap may not be feasible in certain situations. In this study, we objectively evaluated functional and cosmetic outcomes following single soft‐tissue flap reconstruction in a group of patients where double flap reconstruction was not feasible. Patient and defect characteristics were obtained from charts. The speech and swallowing functions of patients were prospectively assessed by a dedicated therapist. The cosmetic outcome of reconstruction was evaluated by an independent observer. Fifty‐six patients with large soft tissue and segmental posterolateral mandible defect, reconstructed with anterolateral thigh or pectoralis major flap from May 2009 till December 2010 were included. In this series, none of the flaps were lost; two patients with pectoralis major flap developed partial skin paddle loss. Most of the patients developed mandibular drift; however, majority of these patients had no postoperative trismus. All patients resumed regular or soft solid oral diet. The mean speech intelligibility was more than 70%. Majority of patients had satisfactory cosmetic outcome. The defects were classified into regions resected to develop a reconstruction algorithm for optimal reconstruction using a free or pedicle flap. In conclusion, patients with large oro‐mandibular defect undergoing single soft tissue flap reconstruction have satisfactory functional and cosmetic outcome. © 2012 Wiley Periodicals, Inc. Microsurgery, 2013.
Latissimus dorsi flap harvest with a short incision
Authors: Tan Onder , Aydin Osman Enver , Cinal Hakan , Barin Ensar Zafer , Algan Said , Kuduban Selma Denktas , Kara Murat , Inaloz Akin 
Published: December 2012

AbstractLatissimus dorsi (LD) flap is one of the most common options utilized in reconstructive armamentarium. In this report, we present our experience on harvest of the full LD muscle flap through a short incision. Twelve free and two pedicled full LD muscle flaps were raised in 14 patients (9 males and 5 females). In this technique, an oblique incision was placed 5–7 cm caudal to axillary apex, beginning from the posterior axillary line, so as to center the neurovascular hilus. The length of incision was 10 cm in adults and 8 cm in children. Mean dissection time was 45 min. All flaps survived totally. Seroma formation developed in two cases and treated with syringe aspiration and compressive dressing. In late postoperative period, donor site scars became inconspicuous and patient satisfaction was high. Short incision technique may be a good option to overcome scar problems in donor site of the LD flap. The technique reduces the dissection time and does not require sophisticated surgical devices and skill, when compared to endoscopic LD flap harvesting from the literature. © 2012 Wiley Periodicals, Inc. Microsurgery, 2013.