bluuebunny/crossref_metadata_2025_split huggingface dataset:
Water drinking in snakes: Evidence for an esophageal sphincter
Authors: Bels Vincent L. , Kardong Kenneth V. 
Published: June 2005

AbstractDrinking fluids by snakes, as in many amniotes, requires elevation of water from the substrate into the mouth, then passage through the pharynx into the esophagus. A model of oral transport of fluids in snakes, the buccal‐pump mechanism, predicts that snakes possess a functional sphincter guarding retrograde flow of accumulating fluid from the esophagus, and that intraoral transport proceeds sequentially under active pressure generation by the buccal‐pump mechanism. Cineradiographic images and kinematic profiles of fluid transport were analyzed to test these predictions. Our results confirm the following: 1) the presence of a temporary esophageal sphincter, which prevents retrograde passage of fluid from the esophagus back into the mouth. 2) During each rhythmic drinking cycle, positive and negative pressure surges generated by the oropharyngeal cavity first aspirate fluid into the mouth then drive it intraorally, past the esophageal sphincter, and into the esophagus where each pulse of fluid contributes to a growing reservoir of water. 3) The oropharyngeal cavity is functionally divided into anterior and posterior tandem chambers that pump fluid sequentially from one (anterior) to the other (posterior), which then empties into the esophagus. 4) In large snakes, capillarity is not a significant force contributing to intraoral transport of water. These findings support the proposed buccal‐pump models of fluid drinking by snakes. © 1995 Wiley‐Liss, Inc.
Fibroblast growth factor‐2 immunoreactivity is present in the central and peripheral auditory pathways of adult rats
Authors: Silva Vivian Alessandra , Gomide Vânia Canterucci , Chadi Gerson 
Published: June 2005

AbstractRecent findings have pointed out the role of neurotrophic factors in the survival and maintenance of neurons of the auditory system. Basic fibroblast growth factor (bFGF, FGF‐2) is a potent neurotrophic molecule whose actions can be seen in the central and peripheral nervous systems. In the present study, FGF‐2 immunoreactivity was analyzed in the auditory pathways of the adult rat, employing a well‐characterized polyclonal antibody against FGF‐2. In the cochlea, FGF‐2 immunoreactivity was observed in the inner and outer hair cells of the organ of Corti, spiral ganglion neurons, spiral limbus, and stria vascularis. Stereological methods employing optical fractionator revealed the presence of 84.5, 15, and 0.5% of spiral ganglion neurons possessing FGF‐2 immunoreactivity of strong, moderate, and weak intensity, respectively. In the central auditory pathways, FGF‐2 immunoreactivity was found in the cytoplasm of the neurons of the cochlear nuclei, trapezoid body nuclei, medial geniculate nucleus, and inferior colliculus. The two‐color immunoperoxidase method showed FGF‐2 immunoreactivity in the nuclei of astrocytes throughout the central auditory pathway. Computer‐assisted microdensitometric image analysis revealed higher levels of specific mean gray values of FGF‐2 immunoreactivity in the trapezoid body and ventral cochlear nucleus and also in the spiral ganglion and inner hair cells. Sections incubated with FGF‐2 antibody preabsorbed with human recombinant FGF‐2 showed no immunoreaction in the majority of the studied regions, exhibiting only a slight immunoreactive product in the hair cells of the organ of Corti. Furthermore, no changes in immunoreactivity were observed in sections incubated with FGF‐2 antiserum preincubated with human recombinant acidic FGF (FGF‐1). The findings suggest that FGF‐2 may exert paracrine and autocrine actions on neurons of the central and peripheral auditory systems and may be of importance in the mechanism of hearing diseases. J. Morphol. © 2005 Wiley‐Liss, Inc.
Interpretation of butyltin mass spectra using isotope pattern reconstruction for the accurate measurement of isotope ratios from molecular clusters
Authors: Meija Juris , Centineo Giuseppe , Ignacio Garcia Alonso J. , Sanz‐Medel Alfredo , Caruso Joseph A. 
Published: June 2005

AbstractThe fragmentation patterns of butyltin compounds (mono‐, di‐, and tributyltin) in an electron impact ion source were studied using an isotope pattern reconstruction algorithm with emphasis on isotope ratio measurements from molecular clusters. For this purpose, standards of natural tin isotope abundance and a 119Sn‐enriched mixture of the three compounds were both ethylated and propylated using sodium tetraalkylborates. The corresponding mass spectra of the various tetraalkyltin compounds prepared were obtained by GC/MS after their extraction with hexane.The results showed that pure interference‐free molecular clusters were obtained only for certain R3Sn+ ions where no isobaric overlap with R2SnH+ ions occurred (e.g. BuEt2Sn+ overlaps with Bu2SnH+). These ions are ideal candidates for accurate Sn isotope ratio measurements, while isotope pattern perturbing interferences are observed for other molecular fragments down to Sn•+. Isotope pattern reconstruction algorithm thus can be used as an analytical tool to ensure the absence of molecular interferences—a requirement for accurate isotope ratio measurements from molecular clusters. The relevance of these studies for the determination of butyltin compounds in environmental samples by isotope dilution GC/MS is also discussed. Copyright © 2005 John Wiley & Sons, Ltd.
New Enantiomeric Polylactide‐block‐Poly(butylene succinate)‐block‐Polylactides: Syntheses, Characterization and in situ Self‐Assembly
Authors: Jia Lin , Yin Lingzhi , Li Yang , Li Qiaobo , Yang Jing , Yu Jianyong , Shi Zhen , Fang Qiang , Cao Amin 
Published: June 2005

AbstractSummary: In situ self‐assemblies of new biodegradable triblock PLLA‐b‐PBS‐b‐PLLA and PDLA‐b‐PBS‐b‐PDLA have been investigated in acetonitrile solution. At first, two series of PLLA‐b‐PBS‐b‐PLLA and PDLA‐b‐PBS‐b‐PDLA, respectively denoted as the P and Q triblock copolyester series, were prepared with fixed PBS block ($\overline M _{{\rm n},{\rm NMR}}$ = 6.9 kDa) and diverse enantiomeric PLLA/PDLA blocks. Further, their chemical structures and thermal properties were characterized by means of titration, nuclear magnetic resonance spectroscopy (NMR), gel permeation chromatography (GPC), polarimeter, wide‐angle X‐ray diffraction (WAXD) and thermal analytical instruments. When mixing the synthesized enantiomeric copolyester pairs denoted as P1/Q1 – P8/Q8 in acetonitrile solution at 60 °C, in situ self‐assemblies were found to happen for the P4/Q4 to P8/Q8 pairs, bearing longer enantiomeric PLA block lengths. DSC and WAXD analysis of the self‐assembled microparticles demonstrated that PLLA/PDLA racemic crystals were formed for the P5/Q5 – P8/Q8 systems, as evidenced by their melting points over 200 °C, and a new X‐ray diffraction peak detected at 2θ = 11.8°. Moreover, morphological studies by scanning electron microscopy (SEM) indicated the formation of disk‐ or platelet‐like microparticles. It was noted that the diameters of the microparticles self‐assembled in situ decreased from 1.28–1.50 μm down to 480–660 nm, through tailoring the enantiomeric PLA block length. Other factors, such as a central PBS block, the enantiomeric block length and the preparation conditions were suggested to play important roles in the in situ self‐assembly of these enantiomeric triblock copolyesters. These results provide a facile way to self‐assemble hydrophobic, biodegradable microparticles, through tuning the important van der Waals stereocomplexation interactions between two enantiomeric blocks in solution.In situ self‐organisation of new PLLA‐b‐PBS‐b‐PLLA and PDLA‐b‐PBS‐b‐PDLA triblock copolyester pairs in dilute solution.magnified imageIn situ self‐organisation of new PLLA‐b‐PBS‐b‐PLLA and PDLA‐b‐PBS‐b‐PDLA triblock copolyester pairs in dilute solution.
Synthesis of and Structural Studies on Repeating Sequences of Abductin
Authors: Bochicchio Brigida , Jimenez‐Oronoz Felipe , Pepe Antonietta , Blanco Mario , Sandberg Lawrence B. , Tamburro Antonio M. 
Published: June 2005

AbstractSummary:Little data exist on the structure and function of compressible elastomeric proteins such as abductin. An understanding of the underlying structural features of these proteins may lead to the development of a new class of highly tailored “compressible” hydrogels. To that effect, in this work, the structure of abductin was investigated by means of studies on several synthetic peptides corresponding to the most frequent sequences of abductin. In particular, the 10 amino acid abductin peptide sequence FGGMGGGNAG, tandem repeated in the protein, and two related 25 and 40 amino acid polypeptides were synthesized. These peptides were studied with regard to secondary structure, self‐assembly, and polymer morphology. The results obtained with these peptides allow us to propose a preliminary structure‐elasticity relationship for abductin not dissimilar from that currently accepted for elastin.A possible mechanism of elasticity relating abductin to elastin.magnified imageA possible mechanism of elasticity relating abductin to elastin.
Folate Receptor‐Mediated Gene Delivery Using Folate‐Poly(ethylene glycol)‐Poly(L‐lysine) Conjugate
Authors: Cho Kyung Chul , Kim Sun Hwa , Jeong Ji Hoon , Park Tae Gwan 
Published: June 2005

AbstractSummary: For efficient receptor‐mediated gene transfection, a new and simple formulation method based on using PEI and FOLPEGPLL conjugate was presented. Luciferase plasmid DNA and PEI were complexed to form slightly positive‐charged nanoparticles, onto which FOL‐PEG‐PLL conjugate was surface coated. With increasing the coating amount of FOL‐PEG‐PLL conjugate, the FOL‐PEG‐PLL/PEI/DNA complexes exhibited increased surface zeta‐potential values with concomitantly increased diameters, indicating that the PLL part was physically anchored on the surface of preformed PEI/DNA complexes with FOL moieties being exposed on the outside. The formulated complexes exhibited a considerably higher transfection efficiency against FOL receptor over‐expressing KB cells than FOL receptor deficient A549 cells. This was caused by an enhanced cellular uptake of the resultant complexes via a receptor‐mediated endocytosis process. The formulated complexes showed a higher gene expression level, even in the presence of serum, than the PEI/DNA or Lipofectamine/DNA complexes. This was attributed to the PEG chains present on the surface of complexes that could work as a protective shield layer against aggregation caused by non‐specific protein adsorption. The FOL‐PEG‐PLL/PEI/DNA complexes also demonstrated better cell viability than the PEI/DNA complexes.1H NMR spectrum of FOL‐PEG‐PLL conjugate.magnified image1H NMR spectrum of FOL‐PEG‐PLL conjugate.
Water‐Soluble Nanoparticles from Random Copolymer and Oppositely Charged Surfactant, 3
Authors: Kizhakkedathu Jayachandran N. , Nisha C. K. , Manorama Sunkara V. , Maiti Souvik 
Published: June 2005

AbstractSummary: In this report, we investigate the nanoparticle formation between random copolymers (RCPs) of methoxy‐poly(ethylene glycol) monomethacrylate (MePEGMA) and (3‐(methacryloylamino)propyl)trimethylammonium chloride (MAPTAC) and oppositely charged natural surfactants, sodium oleate and sodium laurate, using turbidimetric titration, steady‐state fluorescence, dynamic light scattering, and electron microscopy. Though sodium oleate and sodium laurate are sparingly soluble in water, the nanoparticle complexes formed between the RCPs and these surfactants are soluble in the entire range of compositions studied here, including the stoichiometric electronetural complexes. The spherical nature of these nanoparticle complexes is revealed by electron microscopic (EM) analysis. Dynamic light scattering (DLS) showed that the average diameters of the nanoparticles are in the range 50 to 150 nm, which is supported by EM analysis. Pyrene fluorescence experiments suggested that these soluble nanoparticles have hydrophobic cores, which may solubilize hydrophobic drug molecules. The polarity index (I1/I3) obtained from the pyrene fluorescence spectra and the conductometric measurements showed that the critical concentration of fatty acid salts needed to obtain nanoparticles are in the order of 10−4 M. Further, the complexation of such poorly water‐soluble amphiphilic surfactants with polymers offers a useful method for the immobilization of hydrophobic compounds towards water‐soluble drug carrier formulations.The formation of water‐soluble nanoparticles by the self‐assembly of fatty acid salts upon interacting with oppositely charged poly(ethylene glycol)‐based polyions.magnified imageThe formation of water‐soluble nanoparticles by the self‐assembly of fatty acid salts upon interacting with oppositely charged poly(ethylene glycol)‐based polyions.
New Insights into Lamellar Twisting in Transcrystalline Polyethylene
Authors: Ratner Stanislav , Moret P. Mona , Wachtel Ellen , Marom Gad 
Published: June 2005

AbstractSummary: The morphology of the transcrystalline layer grown by nucleating high density polyethylene on fibers of ultra high molecular weight polyethylene was investigated by microbeam synchrotron X‐ray diffraction. Scanning with a 2 micron step size, it was possible to determine that near the fiber surface, the polymer chains of the transcrystalline layer are oriented at an angle of approx. 41° with respect to the fiber axis. This is consistent with the lamellar fold surface (the {201} plane) being close to perpendicular to the fiber axis. The X‐ray data support gradual twisting of the lamellae about the growth direction (the orthorhombic crystallite b‐axis) at a rate of ∼0.85° per micron of radial distance from the fiber surface.Polarized light micrograph of the transcrystalline layer in a PE/PE composite. The width of the fiber is approximately 20 μm.magnified imagePolarized light micrograph of the transcrystalline layer in a PE/PE composite. The width of the fiber is approximately 20 μm.
Chain Extension and Cyclization of Telechelic Polysarcosines
Authors: Kricheldorf Hans R. , v. Lossow Colin , Schwarz Gert , Fritsch Detlef 
Published: June 2005

AbstractSummary: Sarcosine N‐carboxyanhydride (Sar‐NCA) was polymerized with 1,12‐diaminododecane (DAD) or 1,13‐diamino‐4,7,10‐trioxatridecane (DATT) as initiators, and telechelic blocks having two secondary amino endgroups were obtained. Their structure was proven by 1H NMR and MALDI‐TOF mass spectrometry. The SEC measurements indicated narrow molecular weight distribution with polydispersity indices in the range of 1.1–1.2. These difunctional polysarcosines were reacted with three different coupling agents: 4,4′‐diisocyanatodiphenylmethane (MDI), N‐hydroxysuccinimide sebacate, and sebacoyl bisimidazolide. Although the 1H NMR spectra proved high conversions, only a moderate chain extension was observed. The MALDI‐TOF mass spectra indicated a high extent of cyclization, which limited the chain growth.MALDI‐TOF mass spectrum of a DATT‐initiated polysarcosine after reaction with sebacoyl bisimidazolide.magnified imageMALDI‐TOF mass spectrum of a DATT‐initiated polysarcosine after reaction with sebacoyl bisimidazolide.
Are Electrografted Polymers Chemisorbed or Physisorbed onto their Substrate?
Authors: Cuenot Stéphane , Gabriel Sabine , Jérôme Christine , Jérôme Robert , Duwez Anne‐Sophie 
Published: June 2005

AbstractSummary: AFM‐based single‐molecule force spectroscopy was used to evaluate the mechanical strength of the link between a polymer and the substrate onto which the polymer is electrografted. Poly(N‐succinimidyl acrylate) was electrografted onto gold substrates and brought into contact with an aminothiol‐functionalized AFM tip. Bridging of single polymer chains resulting from the strong coupling between the activated esters on the polymer and amine groups on the tip was investigated. We found that the link between the polymer and the gold substrate can withstand a force far beyond the force characteristic for physisorption on gold.
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Photoinduced Polymerization of Thiophene Using Iodonium Salt
Authors: Yagci Yusuf , Yilmaz Faruk , Kiralp Senem , Toppare Levent 
Published: June 2005

AbstractSummary: Thiophene was polymerized by means of UV irradiation using diphenyliodonium hexafluorophosphate as a photoinitiator. An initiation mechanism involving electron transfer from photochemically generated onium radical cations to thiophene was proposed. N‐Ethoxy‐2‐methylpyridinium hexafluorophosphate and triphenylsulfonium hexafluorophosphate were also found to be effective in facilitating the polymerization of thiophene. Polymerization is accompanied with the film formation on the surface of the reaction tube. The photochemically obtained polymers were characterized by FT‐IR, DSC, and SEM analyses and compared with those obtained by oxidative and electrochemical means. Electrical conductivities of the samples were measured by four‐probe technique.Photograph of the polymerization mixture containing thiophene and iodonium salt in CH2Cl2 before (a), after 5 min of irradiation (b), and dried film (c).magnified imagePhotograph of the polymerization mixture containing thiophene and iodonium salt in CH2Cl2 before (a), after 5 min of irradiation (b), and dried film (c).
Streptomycin and EDTA decrease the number of desmin‐negative fibers following stretch injury
Authors: Willems Mark E. T. , Stauber William T. 
Published: June 2005

AbstractStreptomycin and ethylene diamine tetraacetic acid (EDTA) were used to examine the role of extracellular calcium in stretch‐induced muscle injury. Streptomycin was injected in one group of rats, three times daily for 8 days (S, 300 mg.kg−1.day−1 intraperitoneally). In another group, EDTA was administered (150 mg.kg−1 IP) 20 min before and 24 h after the injury protocol. Untreated rats (C) served as controls. Muscle injury was produced by 40 stretches of active dorsiflexor muscles by ankle rotation from 80° to 130° (velocity 1.75 rad.s−1). Ten minutes after the injury protocols, all animals lost the same amount of isometric force at both low and high stimulation frequencies (20 HZ; S, 56 ± 6%; EDTA, 47 ± 7%; C, 55 ± 4%) and 120 HZ; S, 11 ± 3%, EDTA, 13 ± 3%; C, 11 ± 3%). Tibialis anterior (TA) muscles were removed after 48 h for morphometric analysis. In both streptomycin‐and EDTA‐treated rats, the percent of injured (i.e., desmin‐negative) myofibers in TA was reduced compared to untreated, injured muscles (S, 0.35 ± 0.08%; EDTA, 0.64 ± 0.19%; C, 1.81 ± 0.43%). Thus, streptomycin and EDTA treatment did not alter the development of muscle weakness (i.e., isometric force deficit), but almost abolished the histopathologic changes. This study shows that the mechanisms for muscle weakness and histopathologic changes (inflammation) following repeated muscle strains can largely be dissociated from each other and helps explain why there is no correlation between isometric force deficits and the number of pathologic cells. Muscle Nerve, 2005
Acquired nucleic acid changes may trigger sporadic amyotrophic lateral sclerosis
Authors: Armon Carmel 
Published: June 2005

AbstractThis article brings together evidence to support the hypothesis that acquired nucleic acid changes are the proximate causes, “triggers,” or “initiators” of sporadic amyotrophic lateral sclerosis (ALS). Clinical features that support this hypothesis include focal onset and spread, and the individualized rate of progression. Clues from the epidemiology of sporadic ALS include the increase in its incidence with age, suggesting accrual of time‐dependent changes, and the emergence of smoking, a known carcinogen, as its first “more likely than not” exogenous risk factor. The identification of any exogenous risk factor suggests that a large proportion of sporadic cases have a triggering mechanism susceptible to that factor. Ingestion of the products of cycad circinalis has been hypothesized to be implicated in causing Western Pacific ALS. Cycad contains both neurotoxic factors and carcinogens. The dissimilarity of Western Pacific ALS from neurotoxic diseases suggests a greater likelihood that the effects of DNA alkylation are its proximate cause. Muscle Nerve, 2005
Corrosion studies of polyaniline/coconut oil poly(esteramide urethane) coatings
Authors: Ahmad Sharif , Ashraf S. M. , Riaz Ufana 
Published: June 2005

AbstractAdvancements in the area of conducting polymers have been towards their application as effective corrosion protective coatings to replace the use of heavy metals as additives in the coatings industries, which are now considered to be an environmental as well as health hazard. With the aim to utilize a sustainable resource based polymer for the development of an anti‐corrosive conducting coating material, coconut oil based conducting blend coatings of polyaniline and poly(esteramide urethane) were prepared by loading different ratios (2, 4 and 8 wt%) of polyaniline in poly(esteramide urethane). Then their physico‐chemical, thermal, morphological, conductivity and anti‐corrosive coating characteristics were investigated. The effect of a 2 year environmental aging process on the coated samples was analyzed by thermal methods as well as by corrosion studies. Results showed that the corrosion protective performance of the blend coatings was far superior than that of plane poly(esteramide urethane). These coatings showed enhanced corrosion protection in acid as well as alkaline environments upto 360 and 192 hr respectively. Conductivity of the blends was found to be in the range 2.5 × 10−5–5.7 × 10−4 S/cm−1. An increase in the thermal stability of the blend coatings and a decrease in their conductivity was noticed in the aged samples which was attributed to the crosslinking effect. The corrosion protective performance of the coatings remained almost unaffected even after 2 years of aging. Copyright © 2005 John Wiley & Sons, Ltd.
Novel high performance RTM bismaleimide resin with low cure temperature for advanced composites
Authors: Gu Aijuan 
Published: June 2005

AbstractA novel performance matrix, coded as LCRTM, with low cure and post‐cure temperature (≤ 200°C) for fabricating advanced polymer composites via resin transfer molding (RTM), was successfully developed, made up of 4,4′‐bismaleimidodiphenylmethane (BDM) and N‐allyl diaminodiphenylether (ADDE). Investigations show that the stoichiometry of BDM and ADDE has great effect on the processing and performance parameters of the resultant resins. In the case of the optimum formulation (the mole ratio of BDM and ADDE is 1:0.55), the injection temperature range is between 70–82°C, and the pot life at 80°C is 300 min, moreover, the cured resin has desirable thermal and mechanical properties after being cured at 200°C for 6 hr, reflecting a great potential as high performance matrices for fabricating advanced composites via the RTM technique. Copyright © 2005 John Wiley & Sons, Ltd.
Poly(L‐histidine) with several aminoethyl groups for a new pH‐sensitive DNA carrier
Authors: Asayama Shoichiro , Sekine Takashi , Hamaya Ai , Kawakami Hiroyoshi , Nagaoka Shoji 
Published: June 2005

AbstractIn this study, poly(L‐histidine) with several aminoethyl groups, i.e. aminated poly(L‐histidine), is reported to be able to make complexes with DNA and to transfect cells in vitro in the presence of serum. The present study was performed to determine whether the pH of the medium had an influence on the complex formation with DNA, on the cell membrane fusion activity and on the transfection efficiency. Agarose gel retardation assays proved that the polyion complex formation of the aminated poly(L‐histidine) with DNA was affected by pH of the medium, owing to the basicity (protonation–deprotonation) of the imidazole groups with a pKa value around 6.0. Hemolysis assay showed that the resulting DNA complex enhanced membrane disruptive ability at endosomal pH. The aminated poly(L‐histidine) gene carrier demonstrated significant transfection efficacy which was decreased by the inclusion of chloroquine as an endosomolytic agent. These results suggest that the aminated poly(L‐histidine) promises to be a new pH‐sensitive DNA carrier for endosomal escape. Copyright © 2005 John Wiley & Sons, Ltd.