bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mimicking the cell membrane with block copolymer membranes
Authors: Zhang Xiaoyan , Tanner Pascal , Graff Alexandra , Palivan Cornelia G. , Meier Wolfgang 
Published: March 2012

AbstractCell membranes are essential barriers in Nature. To understand their properties and functions and to develop desirable applications, a simple and elegant approach is to study membranes that mimic the cell membrane. Lipid bilayers represent simple models that are physiologically representative when in the form of mixtures of various lipids, but they are not adequately stable even when covered with amphipathic proteins or when combined with polymers, thus preventing technological applications. This makes necessary the design of completely synthetic membranes. In this respect, amphiphilic copolymers that self‐assemble under dilute aqueous conditions and generate supramolecular polymer vesicles or films are ideal candidates for synthetic membranes. Their versatility in terms of chemistry and properties (permeability, mechanical stability, thickness), if appropriately designed, enable the insertion of biological molecules, such as membrane proteins and biopores, or the attachment of biomolecules at their surfaces. Here, we present the domain of synthetic membranes based on amphiphilic copolymers beginning with their generation and up to their applications in medicine, the food industry, and technology. Even though significant progress has been made in combining them with membrane proteins, open questions remain with respect to desired properties that could accommodate biological molecules and support further development of the field, from both the point of view of fundamental understanding and of applications. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Methylol‐functional benzoxazines as precursors for high‐performance thermoset polymers: Unique simultaneous addition and condensation polymerization behavior
Authors: Baqar Mohamed , Agag Tarek , Ishida Hatsuo , Qutubuddin Syed 
Published: March 2012

AbstractA new class of high‐performance resins of combined molecular structure of both traditional phenolics and benzoxazines has been developed. The monomers termed as methylol‐functional benzoxazines were synthesized through Mannich condensation reaction of methylol‐functional phenols and aromatic amines, including methylenedianiline (4,4′‐diaminodiphenylmethane) and oxydianiline (4,4′‐diaminodiphenyl ether), in the presence of paraformaldehyde. For comparison, other series of benzoxazine monomers were prepared from phenol, corresponding aromatic amines, and paraformaldehyde. The as‐synthesized monomers are characterized by their high purity as judged from 1H NMR and Fourier transform infrared spectra. Differential scanning calorimetric thermograms of the novel monomers show two exothermic peaks associated with condensation reaction of methylol groups and ring‐opening polymerization of benzoxazines. The position of methylol group relative to benzoxazine structure plays a significant role in accelerating polymerization. Viscoelastic and thermogravimetric analyses of the crosslinked polymers reveal high Tg (274–343 °C) and excellent thermal stability when compared with the traditional polybenzoxazines. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
One‐pot synthesis of hyperbranched glycopolymers by RAFT polymerization
Authors: Wei Zhenke , Hao Xiaojuan , Gan Zhihua , Hughes Timothy C. 
Published: March 2012

AbstractSoluble hyperbranched glycopolymers were prepared by copolymerization of glycan monomers with reversible addition‐fragmentation chain transfer polymerization (RAFT) inimers in a simple one‐pot reaction. Two novel RAFT inimers, 2‐(methacryloyloxy)ethyl 4‐cyano‐4‐(phenylcarbonothioylthio)pentanoate (MAE‐CPP) and 2‐(3‐(benzylthiocarbonothioylthio)propanoyloxy)ethyl acrylate (BCP‐EA) were synthesized and used to prepare hyperbranched glycopolymers. Two types of galactose‐based saccharide monomers, 6‐O‐methacryloyl‐1,2:3,4‐di‐O‐isopropylidene‐D‐galactopyranose (proGal‐M) and 6‐O‐(2′‐acrylamido‐2′‐methylpropanoate)‐1,2:3,4‐di‐O‐isopropylidene‐D‐galactopyranose (proGal‐A), containing a methacrylate and an acrylamide group, respectively, were also synthesized and polymerized under the mediation of the MAE‐CPP and BCP‐EA inimers, respectively. In addition, hyperbranched poly(proGal‐M), linear poly(proGal‐A), and hyperbranched poly(proGal‐A) were generated and their polymerization kinetics were studied and compared. An unexpected difference was observed in the kinetics between the two monomers during polymerization: the relationship between polymerization rate and concentration of inimer was totally opposite in the two monomer–inimer systems. Branching analysis was conducted by using degree of branching (DB) as the measurement parameter. As expected, a higher DB occurred with increased inimer content. Furthermore, these polymers were readily deprotected by hydrolysis in trifluoroacetic acid solution resulting in water‐soluble polymers. The resulting branched glycopolymers have potential as biomimetics of polysaccharides. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Photoinitiated RAFT polymerization of vinyl acetate
Authors: Ham Min‐kyoung , HoYouk Ji , Kwon Yong‐Ku , Kwark Young‐Je 
Published: March 2012

AbstractA photoinitiation process was investigated to develop a rapid and well‐controlled RAFT polymerization method applied to vinyl acetate (VAc) using methyl (ethoxycarbonothioyl)sulfanyl acetate (MESA) and bis(2,4,6‐trimethylbenzoyl)phenylphosphine oxide as the RAFT agent and photoinitiator, respectively. MESA was selected as the photochemically inert RAFT agent to minimize photolysis of the thiocarbonylthio groups during polymerization. Poly(vinyl acetate) with a prespecified well‐controlled molecular weight (MW) and a narrow MW distribution was successfully synthesized. The polymerization reaction proceeded as a living polymerization and was remarkably rapid compared with approaches that use thermally initiated processes with a very short induction period. A detailed kinetic study of the mechanism underlying the polymerization reaction, however, revealed that the chain ends containing xanthate moieties were not perfectly stable upon UV‐irradiation, and they generated radicals via homolytic cleavage. This reaction appeared to proceed by a combination of a degenerative transfer RAFT mechanism and a dissociation‐combination mechanism. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Glu121‐Lys319 salt bridge between catalytic and N‐terminal domains is pivotal for the activity and stability of Escherichia coli aminopeptidase N
Authors: Gumpena Rajesh , Kishor Chandan , Ganji Roopa Jones , Jain Nishant , Addlagatta Anthony 
Published: March 2012

AbstractEscherichia coli aminopeptidase N (ePepN) belongs to the gluzincin family of M1 class metalloproteases that share a common primary structure with consensus zinc binding motif (HEXXH‐(X18)‐E) and an exopeptidase motif (GXMEN) in the active site. There is one amino acid, E121 in Domain I that blocks the extended active site grove of the thermolysin like catalytic domain (Domain II) limiting the substrate to S1 pocket. E121 forms a part of the S1 pocket, while making critical contact with the amino‐terminus of the substrate. In addition, the carboxylate of E121 forms a salt bridge with K319 in Domain II. Both these residues are absolutely conserved in ePepN homologs. Analogous Glu‐Asn pair in tricon interacting factor F3 (F3) and Gln‐Asn pair in human leukotriene A4 hydrolase (LTA4H) are also conserved in respective homologs. Mutation of either of these residues individually or together substantially reduced or entirely eliminated enzymatic activity. In addition, thermal denaturation studies suggest that the mutation at K319 destabilizes the protein as much as by 3.7°C, while E121 mutants were insensitive. Crystal structure of E121Q mutant reveals that the enzyme is inactive due to the reduced S1 subsite volume. Together, data presented here suggests that ePepN, F3, and LTA4H homologs adopted a divergent evolution that includes E121‐K319 or its analogous pairs, and these cannot be interchanged.
The folding pathway of glycosomal triosephosphate isomerase: Structural insights into equilibrium intermediates
Authors: Guzman‐Luna Valeria , Garza‐Ramos Georgina 
Published: March 2012

AbstractThe guanidine hydrochloride‐induced conformational transitions of glycosomal triosephosphate isomerase (TIM) were monitored with functional, spectroscopic, and hydrodynamic measurements. The equilibrium folding pathway was found to include two intermediates (N2↔I2↔2M↔2U). According to this model, the conformational stability parameters of TIM are as follows: ΔGI2‐N2 = 5.5 ± 0.6, ΔG2M‐I2=19.6 ± 1.6, and ΔG2U‐2M = 14.7 ± 3.1 kcal mol−1. The I2 state is compact (αSR = 0.8); it is able to bind 8‐anilinonaphthalene‐1‐sulfonic acid ANS and it is composed of ∼45% of α‐helix and tertiary structure content compared with the native enzyme; however, it is unable to bind the transition‐state analog 2‐phosphoglycolate. Conversely, the 2M state lacks detectable tertiary contacts, possesses ∼10% of the native α‐helical content, is significantly expanded (αSR = 0.2), and has low affinity for ANS. We studied the effect of mutating cysteine residues on the structure and stability of I2 and 2M. Three mutants were made: C39A, C126A, and C39A/C126A. The replacement of C39, which is located at β2, was found to be neutral. The I2–C126A state, however, was prone to aggregation and exhibited an emission maximum that was 3‐nm red‐shifted compared with the I2–wild type, indicating solvent exposure of W90 at β4. Our results suggest that the I2 state comprises the (βα)1‐4β5 module in which the conserved C126 residue located at β5 defines the boundary of the folded segment. We propose a folding pathway that highlights the remarkable thermodynamic stability of this glycosomal enzyme. Proteins 2012; © 2012 Wiley Periodicals, Inc.
First‐principles calculations of spontaneous polarization for TTF‐QBrCl3
Authors: Ishibashi Shoji , Horiuchi Sachio , Kumai Reiji , Terakura Kiyoyuki 
Published: March 2012

AbstractWe have evaluated spontaneous polarization for TTF‐QBrCl3, whose crystal structure is similar to that of TTF‐CA, by first‐principles calculations. The obtained results are compared with those for closely related materials TTF‐CA and TTF‐BA and found to have some similarities to those for TTF‐CA. No magnetic state is found and polarization grows non‐linearly with the adiabatic switching parameter λ when the system varies from the virtual paraelectric state to the actual ferroelectric state. The evaluated spontaneous polarization values are in the same range as the experimental ones.
RECRUITMENT AND SUCCESSIONAL DYNAMICS DIVERSIFY THE SHIFTING HABITAT MOSAIC OF AN ALASKAN FLOODPLAIN
Authors: Mouw J. E.B. , Chaffin J. L. , Whited D. C. , Hauer F. R. , Matson P. L. , Stanford J. A. 
Published: March 2012

ABSTRACTWe measured plant recruitment patterns, successional dynamics, and biophysical processes on laterally expansive floodplains of the Kwethluk River, Alaska. The main channel of this gravel‐bed river frequently avulses and possesses an anabranching plan form. Fluvial processes were interactive with life history processes of riparian plants in determining initial stages of primary succession. Reproductive strategies and herbivory became important factors later in succession. We conducted plant age and compositional surveys to assess patterns of propagule deposition. We found that dispersal strategies of species were an important factor influencing recruitment patterns. Flood‐dispersed seeds resulted in even‐aged cohorts of species persistently segregated in space, based on age data. Sediment characteristics and inundation potential had little influence on seedling distributions. Recruitment was also segregated on the basis of dispersal strategy. At the heads of bars, where vegetative propagules (live drift wood) were entombed during floods, the distributions of species were random. This size‐selective nature of recruitment persisted through time. Vegetation age and distribution patterns were further diversified by the river's legacy of gravel deposition that diversified the primary successional pathway: one associated with ridges and another with swales. Interactions between these pathways and beaver herbivory initiated secondary succession. We used satellite imagery to quantify the extent of floodplain influenced by herbivory and to assess the importance of this driver of secondary succession. We also used high‐resolution aerial imagery and randomly selected sites to provide an unbiased analysis. We classified this imagery to quantify the spatial extent of herbivory and its influence on the initiation of secondary succession. The results showed, in addition to recruitment and successional dynamics, the flood‐plain habitat mosaic was diversified by the initiation of secondary succession. Patch and species composition within the vegetation mosaics were significantly different than those portions of the floodplain engaged in primary succession. Copyright © 2012 John Wiley & Sons, Ltd.
Primary Blast Injuries—An Updated Concise Review
Authors: Yeh Daniel Dante , Schecter William P. 
Published: March 2012

AbstractBlast injuries have been increasing in the civilian setting and clinicians need to understand the spectrum of injury and management strategies. Multisystem trauma associated with combined blunt and penetrating injuries is the rule. Explosions in closed spaces increase the likelihood of primary blast injury. Rupture of tympanic membranes is an inaccurate marker for severe primary blast injury. Blast lung injury manifests early and should be managed with lung‐protective ventilation. Blast brain injury is more common than previously appreciated.
Subcuticular Absorbable Suture with Subcutaneous Drainage System Prevents Incisional SSI after Hepatectomy for Hepatocellular Carcinoma
Authors: Tsujita Eiji , Yamashita Yo‐ichi , Takeishi Kazuki , Matsuyama Ayumi , Tsutsui Shin‐ichi , Matsuda Hiroyuki , Taketomi Akinobu , Shirabe Ken , Ishida Teruyoshi , Maehara Yoshihiko 
Published: March 2012

AbstractBackgroundThe effectiveness of subcuticular absorbable suture with subcutaneous drainage to decrease the risk of postoperative incisional surgical site infection (SSI) in hepatocellular carcinoma (HCC) patients was evaluated.MethodsA total of 149 patients with HCC who underwent hepatectomy (Hx) were retrospectively investigated. Patients were divided into two groups: the patients with subcuticular suture combined with subcutaneous drainage (the drainage group; 61 patients) and the patients with nylon suture without subcutaneous drainage (the nylon group; 88 patients). After the operations, the complication rate of postoperative incisional SSI was analyzed and compared between the two groups.ResultsIn the drainage group the rate of incisional SSI was significantly lower compared to the nylon group: 14–3 % (p = 0.033), respectively. Patients with incisional SSI needed significantly longer postoperative hospital care than the patients without incisional SSI: 28 versus 15 days (p < 0.005). Multivariate analysis revealed that subcuticular absorbable suture with subcutaneous drainage significantly reduced the occurrence of incisional SSI (odds ratio; 0.15; p = 0.034).ConclusionsWe have demonstrated that the subcuticular suture with subcutaneous drainage is effective in preventing incisional SSI in patients undergoing Hx for HCC.
Double Omental Flap Reduced Perianastomotic Collections and Relaparotomy Rates after Pancreaticoduodenectomy with Pancreaticogastrostomy
Authors: Rosso Edoardo , Lopez Patricia , Roedlisch Marie Noel , Narita Masato , Oussoultzoglou Elie , Bachellier Philippe 
Published: March 2012

AbstractIntroductionIn an attempt to reduce the perioperative morbidity after pancreaticoduodenectomy, the results of double omental flap (DOF) after pancreaticoduodenectomy (PD) with pancreaticogastrostomy (PG) were compared to a standard technique.MethodsFrom January 2009 to December 2009, 61 patients underwent PD with PG for pancreatic adenocarcinoma in our department. Perioperative data were prospectively recorded, and postoperative outcome of patients who underwent or not a DOF (group DOF+ = 33 and group DOF− = 28, respectively) was analyzed.ResultsThe overall postoperative mortality was 1.6 % (n = 1). The overall postoperative morbidity rate was 27.8 % (n = 17). PF occurred in eight (13.1 %) patients and was grade A in six (9.8 %) patients. Clinically relevant PF (grade B and C) occurred in two (3.2 %) patients. The univariate analysis showed that in the DOF+ groups there was a significant reduction of perianastomotic collections (P = 0.034) and a significant reduction of the relaparotomy rate (P = 0.05).DiscussionThe DOF contributed to reduce the rate of perianastomotic collections as well as the rate of relaparotomy.ConclusionsA DOF should be considered a further step toward a reduction of surgical‐related complications after PD with PG.
Laparoscopic Appendectomy Outcomes on the Weekend and During the Week are no Different: A National Study of 151,774 Patients
Authors: Worni Mathias , Østbye Truls , Gandhi Mihir , Rajgor Dimple , Shah Jatin , Shah Anand , Pietrobon Ricardo , Jacobs Danny O. , Guller Ulrich 
Published: March 2012

AbstractBackgroundThe “weekend effect” is defined as increased morbidity and mortality for patients admitted on weekends compared with weekdays. It has been observed for several diseases, including myocardial infarction and renal insufficiency; however, it has not yet been investigated for laparoscopic appendectomy in acute appendicitis—one of the most prevalent surgical diagnoses.MethodsThe present study is based on the Nationwide Inpatient Sample (NIS) from 1999 to 2008. The following outcomes were compared between patients undergoing laparoscopic appendectomy for acute appendicitis admitted on weekdays versus weekends: severity of appendicitis, intraoperative and postoperative complications, conversion rate, in‐hospital mortality, and length of hospital stay. Unadjusted and risk‐adjusted generalized linear regression analyses were performed.ResultsOverall, 151,774 patients were included, mean age was 39.6 years, 52.6% (n = 79,801) were male, and 25.3% (n = 38,317) were admitted on weekends. After risk adjustment, the conversion rate was lower [odds ratio (OR): 0.94, p = 0.004, number needed to harm (NNH): 244], whereas pulmonary complications (OR: 1.12, p = 0.028, NNH: 649) and reoperations (OR: 1.21, p = 0.013, NNH: 1,028) were slightly higher on weekends than on weekdays. Overall postoperative complications (OR: 1.03, p = 0.24), mortality (OR: 1.37, p = 0.075) and length of hospital stay (mean on weekday: 2.00 days, weekends: 2.01 days, p = 0.29) were not statistically different.ConclusionsThe present investigation provides evidence that no clinically significant “weekend effect” for patients undergoing laparoscopic appendectomy exists. Therefore, hospital or staffing policy changes are not justified based on the findings from this large national study.
Evidence of serologic activity in chronic hepatitis B after surface antigen (HBsAg) seroclearance documented by conventional HBsAg assay
Authors: Seto Wai-Kay , Tanaka Yasuhito , Wong Danny Ka-Ho , Lai Ching-Lung , Shinkai Noboru , Yuen John Chi-Hang , Tong Teresa , Fung James , Hung Ivan Fan-Ngai , Yuen Man-Fung 
Published: March 2012

Abstract

Background
Possible serologic activity after hepatitis B surface antigen (HBsAg) seroclearance documented by conventional assays in chronic hepatitis B (CHB) has not been thoroughly investigated.

Methods
We determined the levels of serum hepatitis B virus (HBV) DNA, hepatitis B core-related antigen (HBcrAg), and linearized HBsAg (CLEIA prototype) in 329 CHB patients (72.0% male) after HBsAg seroclearance was documented by a conventional HBsAg assay.

Results
The median interval between presentation and HBsAg seroclearance was 69.4 months. The median age at HBsAg seroclearance was 50 years. Assays for serum HBV DNA, HBcrAg, and linearized HBsAg were performed at a median time interval of 11.2 months after HBsAg loss. Linearized HBsAg and HBcrAg were detectable in 85 (25.8%) and 69 (21%) patients, respectively, and one or both serologic markers were detectable in 133 patients (40.4%). Serum HBV DNA was detectable in only 7 patients (2.1%). There was no correlation between linearized HBsAg and HBcrAg levels (r = 0.095, p = 0.924). The incidences of detectable linearized HBsAg and HBcrAg did not differ between patient samples taken at 6–12 and >12 months after HBsAg seroclearance (p = 0.146 and 0.079, respectively). Among patients with detectable serologic markers, median levels of linearized HBsAg (p = 0.581) and HBcrAg (p = 0.951) did not significantly change with time after HBsAg seroclearance.

Conclusion
Using novel HBcrAg and linearized HBsAg assays, viral serologic activity after HBsAg seroclearance was demonstrated in more than 40% of CHB patients. These tests have potential applications in diagnosing and prognosticating CHB patients with HBsAg seroclearance.
Singleton pregnancy outcomes after assisted and non‐assisted reproductive technology in infertile patients
Authors: Tsutsumi Ryo , Fujimoto Akihisa , Osuga Yutaka , Ooi Nagisa , Takemura Yuri , Koizumi Minako , Yano Tetsu , Taketani Yuji 
Published: March 2012

AbstractPurposeSingleton pregnancy after assisted reproductive technology (ART) has been associated with higher risks of adverse pregnancy outcome than naturally conceived singleton pregnancy. This study was to elucidate whether the ART procedure is responsible for abnormal pregnancy outcome comparing those after ART and non‐ART in infertile patients.MethodsWe compare the singleton pregnancy outcome of infertile patients in our university hospital between 2000 and 2008 following ART (351 pregnancies) and non‐ART (213 pregnancies) procedures. Pregnancy outcome parameters were incidence of pregnancy induced hypertension, placenta previa, placental abruption, cesarean delivery, preterm birth, very preterm birth, stillbirth, low birth weight and very low birth weight.ResultsMost of the pregnancy outcome parameters were not significantly different between the ART group and the non‐ART group. Only placenta previa was significantly higher in the ART group than in the non‐ART group (odds ratio 4.0; 95 % CI 1.2–13.7).ConclusionsART procedure may itself be a risk factor for the development of placenta previa. Some of the abnormal perinatal outcomes that had been previously attributed to ART, however, may be due to the baseline characteristics of infertile patients.