bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of Ring Implant Surgeries on the Corneal Transplant Queue at a Reference University Hospital in the State of Pará
Authors: Guimarães Glenda Figueira , Filho José Jesu Sisnando D'Araujo , Oliveira Raissa Tereza Casseb , Moraes Evelly Christinne da Silva , Nascimento Kelly Cristina Costa Guedes , Amorim Ryan Jorge , Carvalho Pedro Artur Solano , Chaves Caio Cesar Rodrigues , Rodrigues Bruno Eduardo da silva , Sousa Daniele Salgado de , Lima Vitor Hugo Auzier
Published: March 2024

Keratoconus is a progressive non-inflammatory ectatic dystrophy, characterised by thinning and curving of the cornea, with central or paracentral conical protrusion, which occurs due to a biomechanical failure of the corneal stroma that is no longer able to resist the internal and external pressures exerted. The objective of the study was to analyse the positive impact of performing ring implant surgeries on patients on the corneal transplant waiting list, at the Bettina Ferro de Souza University Hospital (HUBFS), in 2023. Of the 87 intrastromal ring implants performed in 2023, 6 patients were excluded due to lack of complete data to carry out the evaluation of this work, using the total number of patients for this research 81 (100%). It was found that 89% of patients showed an improvement in corrected visual acuity after ring implantation, with approximately half reaching 100% of their visual range, providing a visual acuity of 1.0. This study showed that of the 14 patients enrolled for corneal transplantation with keratoconus who also had an indication for ring implantation, only 4 still required corneal transplantation after the procedure. In this sphere, it was evident that the patients had an improvement in visual acuity, symptoms and postponed or canceled the corneal transplant. However, more research is needed in this field, in order to obtain advances that make this procedure even safer, minimizing the risks inherent to its placement, with a view to improving the patient's quality of life.
Studies on Association of Seed Borne Mycoflora in Different Varieties of Black Gram [Vigna mungo (L.) Hepper] by Incubation Methods
Authors: Netam Kiran , Toppo Nisha , Sahu Suresh Kumar , Shankar Gote Sachin , Verma Sushma , Khare N.
Published: March 2024

The present study was conducted to detect and identify seed-borne pathogenic fungi in some different varieties of black gram and their effect on seed germination. Six varieties of black gram (Indira urd-1, Pratap-1, KU-96, TPU-4, TIU-22) and local variety collected from village for experiment. The Eleven seed associated mycoflora recorded were Aspergillus flavus Aspergillus niger, Fusarium spp., Alternaria spp., Rhizopus spp., Penicillium spp., Curvularia spp., Cladosporium spp., Colletotrichum spp., Chaetomium spp. and Trichoderma spp. were detected and identified from the seeds of  different varieties of black gram  by using the standard blotter method, agar plate method, 2,4-D blotter method, roll paper towel method and deep freeze method. In all these methods, poor germination percentage was recorded in local variety, may be due to the presence of seed associated mycoflora with maximum frequency, whereas KU-96 variety has most extreme germination percentage due to the minimum frequency of seed associated mycoflora as compared to other varieties of black gram taken in the examination.
Numerical Study of a Thermal Plume Developing in a Neutral Environment and in Interaction: Application to Fires Problems
Authors: Yahya Zeinebou , Alharbi Mulook Masoud
Published: March 2024

This study focuses on the mathematical and numerical modelling of how different properties, such as channel length and hot source height, affect the flow of thermal plumes and their interaction with the surrounding environment. Studying the behaviour of a directed thermal plume flow can provide a good visualisation of the control parameters for various applications related to fires and pollutants. To determine the control parameters affecting this flow, it is imperative to initially analyse the flow through a natural convection consisting of a disc-shaped heat source at the inlet of a vertical cylinder using mathematical and numerical methods. The flow in this study is characterised by natural convection, turbulent, steady, two-dimensional and incompressible. Numerical results were obtained via computational fluid dynamics analysis, which is based on mathematical flow modelling using the system of Navier–Stokes equations and the finite volume method.  The SIMPLE algorithm was used for the velocity–pressure coupling. After introducing the concept of Reynolds averaging and analysis, different RANS turbulence models are presented, particularly two-equation models, using the Ansys Fluent software. Comparison of the different profiles revealed the ideal flow control parameters.  An improvement in thermal properties was observed when the height of the heat source was  = 1.5 cm and the vertical length of the channel was D = 20cm.
Structural identifiability analysis of the dynamic gas–liquid film model
Authors: Navarro‐Laboulais J. , Cardona S. C. , Torregrosa J. I. , Abad A. , López F.
Published: June 2006

A structural identification analysis of the dynamic gas–liquid film model is applied to identify its theoretically accessible parameters. The analysis was performed considering the different experimental situations found in nonstationary bubble‐column reactors. The system has been modeled considering both the liquid and the gas phases in a well‐mixed flow regime with a global second‐order irreversible chemical reaction. To describe the mass‐transfer phenomenon at the gas–liquid interface level, chemical reactions and diffusive mass transport were considered simultaneously in the liquid film. The identifiability analysis shows that the simultaneous measurement of concentrations in the liquid and the gas phases is required to determine the parameters. Furthermore, model parameters such as the diffusion coefficients, the specific interfacial area, or the film thickness cannot be uncoupled from other parameters, although the kinetic rate constants could be identified in the fast or slow chemical regimes. It is demonstrated that the specific interfacial area cannot be measured from chemical data coming from a nonstationary bubble‐column reactor. This result is discussed with respect to the classical Danckwerts' method for determination of the interfacial area in gas–liquid equipment. © American Institute of Chemical Engineers AIChE J, 2006
Cerebral representation of the anorectum using functional magnetic resonance imaging
Authors: Bittorf B , Ringler R , Forster C , Hohenberger W , Matzel K E
Published: June 2006

Background

Anorectal continence depends not only on the organs of continence but also on cerebral control. There are relatively few data regarding cerebral processing of anorectal continence.

Methods

Thirteen healthy subjects underwent rectal distension to cause urge increasing to discomfort during functional magnetic resonance imaging (fMRI). In addition, a painful heat stimulus was applied to the skin of the anterior abdominal wall in the dermatome corresponding to the rectum. Voluntary contraction of the anal sphincter was also performed. Subjective rating of stimulus intensity was recorded. Evaluation of the data used a general linear model with Brain Voyager™.

Results

Subjective sensation of discomfort increased during repeated rectal distension and caused activation in the anterior cingulate gyrus, insula, thalamus and secondary somatosensory cortex seen on fMRI. Perception of rectal urge and discomfort activated the same cerebral regions with differing intensity. Application of a painful thermal stimulus in the corresponding dermatome showed a modification of the response. Voluntary contraction of the anal sphincter led to activation of the motor cortex and increased activity in the supplementary motor cortex and the insula.

Conclusion

Cerebral representation of the anorectum as mapped by fMRI is intricate and reflects the complexity of the continence mechanism.
19F NMR Chemical Shifts Induced by a Helical Peptide
Authors: Kubasik Matthew A. , Daly Erin , Blom Adam
Published: June 2006

19F NMR spectra of two neutral, organic‐soluble helical peptide octamers, each labeled at its N terminus with either 4‐fluorobenzamide or 4‐trifluoromethylbenzamide, in solvents with widely varying dielectric constants have been observed. The peptides are oligomers of α‐aminoisobutyric acid (Aib), which is a residue known to form stable 310 helices in organic solution. In relation to the 19F NMR spectra of a control molecule, the peptide terminating in 4‐fluorobenzamide shows a solvent‐dependent downfield chemical shift of between ∼1.5 and ∼4 ppm, whilst the peptide terminating in 4‐trifluoromethylbenzamide shows only an ∼0.2 ppm chemical shift dependence on the solvent dielectric constant. The experimental observations were compared to calculated values of the electric field generated by the correlation of dipolar amide units through the peptide’s helical conformation. We find the chemical‐shift response of the 4‐fluorobenzamide group to the peptide’s calculated electric field is consistent with the magnitude of 19F chemical shift dispersion observed in proteins.
On the Sequence of Bond Formation in Loline Alkaloid Biosynthesis
Authors: Faulkner Jerome R. , Hussaini Syed R. , Blankenship Jimmy D. , Pal Sitaram , Branan Bruce M. , Grossman Robert B. , Schardl Christopher L.
Published: June 2006

Loline alkaloids are saturated pyrrolizidines with an oxygen bridge between carbon atoms C‐2 and C‐7 and an amino group on C‐1. They are bioprotective alkaloids produced by Epichloë and Neotyphodium species, mutualistic fungal endophytes that are symbiotic with cool‐season grasses. The sequence of bond formation in loline alkaloid biosynthesis was determined by synthesizing deuterated forms of potential intermediates and feeding them to cultures of the endophyte Neotyphodium uncinatum. These cultures incorporated deuterium from labeled N‐(3‐amino‐3‐carboxypropyl)proline and exo‐1‐aminopyrrolizidine into N‐formylloline. The first result suggests that N‐(3‐amino‐3‐carboxypropyl)proline is the first committed intermediate in loline biosynthesis, and the second result demonstrates that the pyrrolizidine rings form before the ether bridge. The incorporation of these two compounds into lolines and the lack of incorporation of several related compounds clarify the order of bond formation in loline alkaloid biosynthesis.
Photoactivation of an Inhibitor of the 12/15‐Lipoxygenase Pathway
Authors: Herre Stephan , Schadendorf Torsten , Ivanov Igor , Herrberger Christian , Steinle Wencke , Rück‐Braun Karola , Preissner Robert , Kuhn Hartmut
Published: June 2006

Lipoxygenases are lipid‐peroxidizing enzymes that have been implicated in the pathogenesis of inflammatory diseases and lipoxygenase inhibitors may be developed as anti‐inflammatory drugs. Structure comparison with known lipoxygenase inhibitors has suggested that (2Z)‐2‐(3‐benzylidene)‐3‐oxo‐2,3‐dihydrobenzo[b]thiophene‐7‐carboxylic acid methyl ester might inhibit the lipoxygenase pathway but we found that it exhibited only a low inhibitory potency for the pure 12/15‐lipoxygenase (IC50=0.7 mM). However, photoactivation, which induces a Z‐to‐E isomerization of the double bond, strongly augmented the inhibitory potency and an IC50 value of 0.021 mM was determined for the pure E isomer. Similar isomer‐specific differences were observed with the recombinant enzyme and its 12‐lipoxygenating Ile418Ala mutant, as well as in intracellular lipoxygenase activity. Structure modeling of the enzyme/inhibitor complex suggested the molecular reasons for this isomer specificity. Since light‐induced isomerization may proceed in the skin, such photoreactive compounds might be developed as potential drugs for inflammatory skin diseases.
Solid‐Supported [2+2+2] Cyclotrimerizations
Authors: Young Douglas D. , Senaiar Ramesh S. , Deiters Alexander
Published: June 2006

The transition‐metal‐catalyzed [2+2+2] cyclotrimerization of a diyne and an alkyne provides a convergent route to highly‐substituted aromatic rings. This reaction possesses distinct drawbacks, especially low chemo‐ and regioselectivities, which hamper its application in combinatorial synthesis. These problems have been solved by the development of solid‐supported [2+2+2]‐cycloaddition reactions. If conducted on a solid‐support, this reaction enables rapid combinatorial access to diverse sets of carbo‐ and heterocyclic small‐molecule arrays. The scope of this methodology has been investigated by examining different immobilization strategies, different diyne precursors, and a variety of functionalized alkyne reaction partners. Overall, isoindoline, phthalan, and indan libraries were assembled in good to excellent yields and with high purities.
Preparation of Allyltin Reagents Grafted on Solid Support: Clean and Easily Recyclable Reagents for Allylation of Aldehydes
Authors: Chrétien Jean‐Mathieu , Zammattio Françoise , Gauthier Delphine , Le Grognec Erwan , Paris Michaël , Quintard Jean‐Paul
Published: June 2006

The preparation of polymer‐supported allyltin reagents was shown to be possible for both unfunctionalized and functionalized allyl units. These reagents were treated with aldehydes in the presence of cerium(III) or indium(III) salts to afford high yields of homoallylic alcohols, practically uncontaminated with organotin residues (less than 5 ppm). Some mechanism aspects are briefly discussed and the potential for regeneration and reuse of these supported reagents is pointed out.
Self‐Assembly and Molecular Dynamics of Oligoindenofluorenes
Authors: Elmahdy Mahdy M. , Floudas George , Oldridge Luke , Grimsdale Andrew C. , Müllen Klaus
Published: June 2006

The optical properties, self‐assembly mechanism, thermal properties, and the associated molecular dynamics of a series of stable blue‐emitting oligoindenofluorenes up to the polymer were investigated by photoluminescence, wide‐angle X‐ray scattering, polarizing optical microscopy, differential scanning calorimetry, and dielectric spectroscopy. Oligomers of indenofluorenes possess high structural order and form smectic mesophases, as opposed to the nematic mesophases formed in the corresponding oligofluorenes. The α process associated with the liquid‐to‐glass transition displays an asymmetric broadening of relaxation times (non‐Debye process), with a non‐Arrhenius temperature dependence of relaxation times and a strong molecular weight dependence. The low dielectric loss and low ionic conductivity revealed the absence of ketone structural defects, which is consistent with the observed stable blue emission.
New Dinuclear Face‐ and Edge‐Sharing Bioctahedral Ruthenium Compounds Containing 1,2‐Bis(diphenylphosphanyloxy)ethane
Authors: Bravo Jorge , Castro Jesús , García‐Fontán Soledad , Rodríguez‐Martínez M. Carmen , Rodríguez‐Seoane Pilar
Published: June 2006

The bidentate diphosphinite ligand 1,2‐bis(diphenylphosphanyloxy)ethane (L), Ph2P–O–(CH2)2–O–PPh2, can be sequentially incorporated into a series of dinuclear chloro‐bridged ruthenium compounds using [RuCl2(DMSO)4] as a precursor to give the new bioctahedral compounds [Ru2(μ‐Cl)3(DMSO)3Cl(η2‐L)] (1), [Ru2(μ‐Cl)3(DMSO)Cl(η2‐L)2] (2) and [Ru2Cl2(η2‐L)2{η1‐L(O)}2(μ‐Cl)2] (3). Compound 3 contains two partially oxidised diphosphinite ligands that act in a monodentate manner. These compounds can also be obtained by direct reaction of [RuCl2(DMSO)4] with the appropriate stoichiometric amount of L but in the case of 3 (in which prolonged heating is necessary) the reaction affords two mononuclear compounds [RuCl2(η2‐L)(Ph2POPPh2)] (7) and [RuCl(CO)(η2‐L)(Ph2POCH2)] (8), with ligand fragments coordinated to the metal probably originating in metal‐mediated disruptions of L. Reaction of 2 with the monodentate ligands PPh3 – n(OEt)n (n = 1–3) (L′) affords the dinuclear doubly chloro‐bridged compound [Ru2(μ‐Cl)2Cl2(η2‐L)2(L′)2] (4), the dinuclear triply chloro‐bridged compound [{Ru(η2‐L)(L′)}2(μ‐Cl)3]Cl (5) and the mononuclear compound [RuCl2(η2‐L)(L′)2] (6). The solid‐state structures of 2 (transoid isomer), 5 (transoid isomer), 6, 7 and 8 are reported. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Characterization of a Byproduct in the Alkylation of DMIT: Alkylation on the Least Nucleophilic Sulfur Atom
Authors: Petersen Bo M. , Bjernemose Jens K. , Jeppesen Jan O.
Published: June 2006

It is generally accepted that the alkylation of (Et4N)2[Zn(DMIT)2] (1) is a very clean reaction that produces 4,5‐bis(alkylthio)‐1,3‐dithiole‐2‐thiones 4 in very high yields. Although this procedure has been widely used, we have found that, in addition to the 4,5‐bis(alkylthio)‐1,3‐dithiole‐2‐thione products 4, highly unexpected byproducts are formed during the alkylation reaction in which the thione functionalities of DMIT in (Et4N)2[Zn(DMIT)2] (1) are alkylated instead of the more reactive thiolate groups. These byproducts were identified as a novel type of compounds, namely bis(2‐alkylthio‐1,3‐dithiol‐1‐ium‐4,5‐dithiolato)zinc compounds 3, being composed of two identical 2‐alkylthio‐1,3‐dithiol‐1‐ium‐4,5‐dithiolate moieties coordinated to a single zinc(II) atom and were characterized by elemental analyses and different spectroscopic techniques as well as single‐crystal X‐ray structure analyses. A comparison of the physical properties of compounds 3 and (Et4N)2[Zn(DMIT)2] (1) has been carried out. The outcome of these investigations revealed significant differences in the physical properties of these two systems. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Spectroscopic, Structural and Theoretical Investigation of Alkenyl Ruthenium Complexes Supported by Sulfur–Nitrogen Mixed‐Donor Ligands
Authors: Wilton‐Ely James D. E. T. , Wang Ming , Benoit David M. , Tocher Derek A.
Published: June 2006

A series of molecules bearing both sulfur and nitrogen donors has been investigated as ligands for σ‐alkenyl ruthenium complexes. On deprotonation, the ligands, 4‐amino‐2‐mercaptopyrimidine (HL1), 2‐amino‐5‐mercapto‐1,3,4‐thiadiazole (HL2), 2‐mercaptothiazoline (HL3), 4‐hydroxy‐2‐mercaptopyrimidine (HL4) and 2‐mercaptoquinoline (HL5) all react with alkenyl complexes of the form [RuRCl(CO)(BTD)(PPh3)2] [R = CH=CHC6H5, CH=CHC6H4Me‐4, C(C≡CPh)=CHPh; BTD = 2,1,3‐benzothiadiazole] through loss of chloride and BTD ligands to yield [RuR(L)(CO)(PPh3)2]. Four of these ligands have alternative potential coordination modes and donor groups. In all cases complexation occurs to form four‐membered nitrogen–sulfur chelates with the pendant amino or hydroxy functionality playing no role in coordination. In the case of the 4‐aminopyrimidine‐2‐thiolate (L1) ligand, this was confirmed by a single‐crystal X‐ray study. 2‐Mercaptothiazoline (L3) has the ability to coordinate through two sulfur donors, however, chelation to nitrogen and sulfur donors is preferred as demonstrated by a structural study. This observation is supported by theoretical calculations, which show that a complex displaying the nitrogen–sulfur chelate is of significantly lower energy than one bonded to the ligand through two sulfur donors, despite lone pairs being available in both cases. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Evaluation of the radioprotective effect of Liv 52 in mice
Authors: Jagetia Ganesh C. , Ganapathi Narsipura G. , Venkatesh Ponemone , Rao Nageshwar , Baliga Manjeshwar S.
Published: June 2006

Liv 52 is a mixture of botanicals that is used clinically to treat various hepatic disorders. In this study, the radioprotective activity of Liv 52 was evaluated in mice given whole‐body exposure to different doses of γ‐radiation. In addition, a series of studies was conducted to explore the mechanism of radioprotection. Radioprotection was evaluated by the ability of Liv 52 to reduce both the frequency of bone marrow micronucleated erythrocytes and the lethality produced by 60Co γ‐radiation. Mice were treated by oral gavage once daily for seven consecutive days with 500 mg/kg body weight Liv 52 or carboxymethylcellulose vehicle prior to radiation. Micronucleated polychromatic erythrocytes (MPCEs), micronucleated normochromatic erythrocytes (MNCEs), and the PCE/NCE ratio were measured at 0.25–14 days after exposure to whole‐body radiation doses of 0, 0.5, 1.5, 3.0, or 4.5 Gy; animal survival was monitored after doses of 7, 8, 9, 10, 11, or 12 Gy. Pretreatment of mice with Liv 52 significantly reduced the frequency of radiation‐induced MPCEs and MNCEs. Irradiation reduced the PCE/NCE ratio in a dose‐related manner for up to 7 days following irradiation; Liv 52 pretreatment significantly mitigated against these reductions. Liv 52 treatment also reduced the symptoms of radiation sickness and increased mouse survival 10 and 30 days after irradiation. Liv 52 pretreatment elevated the levels of reduced glutathione (GSH), increased the activities of glutathione transferase, GSH peroxidase, GSH reductase, superoxide dismutase, and catalase, and lowered lipid peroxidation (LPx) and the activities of alanine amino transferase and aspartate aminotransferase 30 min after exposure to 7 Gy of γ‐radiation. Liv 52 pretreatment also reduced radiation‐induced LPx and increased GSH concentration 31 days following the exposure. The results of this study indicate that pretreatment with Liv 52 reduces the genotoxic and lethal effects of γ‐irradiation in mice and suggest that this radioprotection may be afforded by reducing the toxic effects of the oxidative products of irradiation. Environ Mol. Mutagen., 2006. © 2006 Wiley‐Liss, Inc.
A brief overview of mechanisms of mitochondrial toxicity from NRTIs
Authors: Kohler James J. , Lewis William
Published: June 2006

Nucleoside reverse transcriptase inhibitors (NRTIs) in combinations with other antiretrovirals (highly active antiretroviral therapy, HAART) are the cornerstones of AIDS therapy, turning HIV infection into a manageable clinical entity. Despite the initial positive impact of NRTIs, therapeutic experience revealed serious side effects that appeared to originate in the mitochondria and which ultimately manifested as dysfunction of that organelle. It may be reasonable to consider that as the AIDS epidemic continues and as survival with HIV infection is prolonged by treatment with HAART, long‐term side effects of NRTIs may become increasingly common. This consideration may be underscored in children who are born to HIV‐infected mothers who received NRTI therapy in utero during gestation. The long‐term effect of that NRTI exposure in utero is not clear yet. This review examines some proposed mechanisms of NRTI mitochondrial toxicity, including genetic predisposition, defects in mitochondria DNA replication, the encompassing “DNA pol‐γ hypothesis,” the relationship between mitochondrial nucleotide and NRTI pools, mitochondrial DNA mutation and dysfunction, and oxidative stresses related to HIV infection and NRTIs. Mechanisms of mitochondrial toxicity are reviewed with respect to key cell biological, pathological, and pharmacological events. Environ. Mol. Mutagen., 2006. © 2006 Wiley‐Liss, Inc.
The research and development strategy for water utilisation in agriculture–responding to diverse needs of farmers in South Africa
Authors: Backeberg Gerhard R. , Sanewe Andrew J.
Published: June 2006

Major differences exist between the environment in which research is carried out and farming is practised. The challenge for research is to develop an agenda and design projects that address real‐life problems. On a national and regional level, key issues for research include increased productivity of water for crop and livestock production and eradication of hunger and poverty. More specifically, utilisation and development of water resources must therefore be analysed in relation to the needs and requirements of people. People using water in agriculture comprise a diverse group of subsistence, emergent and commercial farmers within interrelated subsectors of agriculture such as irrigated and dryland farming, woodlands and forestry, grasslands and livestock watering, and aquaculture. The strategic implementation plan for research and development (R&D) must determine objectives, adopt a course of action and allocate resources. Taking research into practice must be purposefully managed according to the innovation cycle. Using estimation of crop water requirements and irrigation water scheduling as examples, it is shown that high‐quality research has to be followed by comprehensive knowledge dissemination to achieve successful application. More emphasis should be placed on development through technology exchange, training and extension in order to narrow the gap between research and practice. Copyright © 2006 John Wiley & Sons, Ltd.
Cell mimetic lateral stabilization of outer cell mimetic bilayer on polymer surfaces by peptide bonding and their blood compatibility
Authors: Kaladhar K. , Sharma Chandra P.
Published: June 2006

The biological lipid bilayer membranes are stabilized laterally with the help of integral proteins. We have simulated this with an optimized ternary phospholipid/glycolipid/cholesterol system, and stabilized laterally on functionalized poly methyl methacrylate (PMMA) surfaces, using albumin, heparin, and polyethylene glycol as anchors. We have earlier demonstrated the differences due to orientation and packing of the ternary phospholipid monolayers in relation to blood compatibility (Kaladhar and Sharma, Langmuir 2004;20:11115–11122). The structure of albumin is changed here to expose its interior hydrophobic core by treating with organic solvent. The interaction between the hydrophobic core of the albumin molecule and the hydrophobic core of the lipid molecules is confirmed by incorporating the molecule into bilayer membranes. The secondary structure of the membrane incorporated albumin is studied by CD spectral analysis. The structure of the altered albumin molecule contains more β‐sheet as compared to the native albumin. This conformation is also retained in membranes. The partitioning of the different anchors based on its polarity and ionic interactions in the monolayer is studied from the pressure‐area (π‐A) isotherm of the lipid monolayers at the air/water interface using Langmuir‐Blodgett (LB) trough facility. Such two monolayers are deposited onto the functionalized PMMA surface using LB trough and crosslinked by carbodiimide chemistry. The structure of the deposited bilayer is studied by depth analysis using contact mode AFM in dry conditions. The stabilized bilayer shows stability up to 1 month by contact angle studies. Preliminary blood compatibility studies reveal that the calcification, protein adsorption, as well as blood‐cell adhesion is significantly reduced after the surface modification. The reduced adsorption of ions, proteins, and cells to the modified surfaces may be due to the fluidity of the microenvironment along with the contribution of the mobile PEG groups at the surface and the phosphorylcholine groups of the phospholipids. The stability of the anchored bilayer under low shear stress conditions promises that the laterally stabilized supported bilayer system can be used for low shear applications like small diameter vascular graft and modification of biosensors, and so forth. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
In vitro attachment of osteoblasts on contaminated rough titanium surfaces treated by Er:YAG laser
Authors: Friedmann Anton , Antic Lilly , Bernimoulin Jean‐Pierre , Purucker Peter
Published: June 2006

Microbial contamination of implant surfaces inhibits formation of new osseous tissues. Biocompatibility of sandblasted large grid (SLA) surface, after previous in vitro cocultivation with Porphyromonas gingivalis and concomitant Er:YAG laser irradiation of microorganisms, was tested by attachment of newly cultured osteoblasts. A total of 36 customized titanium cubes with SLA surface were placed into human osteoblast culture for 14 days. After removal of 1 control cube, 35 other cubes were contaminated with precultured P. gingivalis (ATCC33277) and incubated in broth medium for 1 week. Ablation was carried out on 32 cubes. Each side was treated for 23.5 s with a pulsed, water‐cooled laser beam. After irradiation, cubes were again placed into fresh osteoblast culture for 2 weeks. One randomly selected single side per cube was analyzed by scanning electron microscope in 22 cubes. On other 10 cubes, vitality of attached cells was tested with ethidiumbromide staining by fluorescence microscopy. Three negative controls revealed constantly adherent P. gingivalis, and no osteoblasts were detectable after P. gingivalis contamination on the surfaces. Laser‐treated specimens showed newly attached osteoblasts, extending over 50–80% of the surface. Positive control cube (without bacterial contamination) showed over 80% cell coverage of the surface. Vitality of widely stretched osteoblasts was confirmed by FITC staining. Our results indicate that Er:YAG laser was effective in removing P. gingivalis and cell compounds, offering an acceptable surface for new osteoblast attachment. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Attachment of human epithelial cells and periodontal ligament fibroblasts to tooth dentin
Authors: Messer Regina L. W. , Davis Cortney M. , Lewis Jill B. , Adams Yolanda , Wataha John C.
Published: June 2006

A goal of treatment in periodontal therapy is to regenerate a new fibroblastic attachment rather than to repair lost attachment with a long junctional epithelium. To date, there is no evidence that fibroblastic attachment formed during regeneration is stronger or less susceptible to periodontal breakdown than a long junctional epithelial attachment. We measured the rate and strength of attachment of epithelial cells (NHEK) and periodontal ligament fibroblasts (PDLF) cultured individually and cocultured to dentin surfaces to determine which cell type has a faster attachment rate and greater adhesive strength to human dentin, and whether the cell types attach independently. Longitudinal dentin slices were seeded with either PDLF or NHEK for 2 or 24 h. The specimens were placed into a parallel plate flow chamber and defined laminar shear stresses were applied. Shear stress was created by step increases in fluid flow rate. Effluent fluid was collected and cell numbers (detached) were counted using a hemocytometer. Cocultures of PDLF and NHEK at three seeding ratios (10:1, 1:1, 1:10) were also tested. Each cell type attached equally well to polystyrene or dentin. PDLF showed a stronger attachment to polystyrene and dentin at 24 versus 2 h. NHEK attached to polystyrene or dentin equally well at 2 and 24 h. NHEK were more strongly attached after 2 h when compared to PDLF. PDLF were more strongly attached after 24 h versus NHEK. When NHEK and PDLF were seeded together on dentin at a 1:1 ratio, PDLF appeared to be more strongly attached than NHEK at 2 but not 24 h. At a ratio of 10 PDLF:1 NHEK, PDLF appeared to be more strongly attached at 2 and 24 h. At a ratio of 1 PDLF:10 NHEK, NHEK appeared to be more strongly attached at 2 h, but PDLF showed a trend of stronger attachment at 24 h. We conclude that epithelial cells attach more quickly to dentin surfaces than PDLF, but do not demonstrate increased attachment strength over time (PDLF do show increased attachment strength overtime). The purported advantages of periodontal regeneration over periodontal repair are supported by our results. Furthermore, our results support the concept of guided tissue regeneration. On the basis of on cellular competition experiments, epithelial cells and PDLF do not act independently, because epithelial cells enhanced the attachment rate of PDLF. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Mechanical properties of OI type III bone tissue measured by nanoindentation
Authors: Fan Zaifeng , Smith Peter A. , Eckstein Eugene C. , Harris Gerald F.
Published: June 2006

Nanoindentation was used to characterize the intrinsic mechanical properties of bone tissue from eight (8) children with type III Osteogenesis Imperfecta (OI). The bone samples were harvested from the cortex portion at the site of bowing (the mid 2/3 of the shaft of the tibia/femur). Unlike normal bone tissue, OI type III cortical bone exhibited more isotropic material properties. Young's modulus and hardness values measured in the longitudinal direction did not show significant differences from the transverse measurements. No differences were observed in modulus or hardness in an analysis of the cortical and trabecular samples. The deformation patterns of the OI type III bone during nanoindentation were found to be similar to those of normal adult bone in an analysis of the ratio of modulus to hardness. No correlation was found between nanoindentation measurement and age in an analysis of regression. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Mimicking cell–cell interactions at the biomaterial–cell interface for control of stem cell differentiation
Authors: Beckstead Benjamin L. , Santosa Daniel M. , Giachelli Cecilia M.
Published: June 2006

The ability to regulate stem cell proliferation and differentiation has relevance in numerous medical applications, including medical devices, tissue engineering, and regenerative medicine. To control cellular behavior at the biomaterial or scaffold interface, many studies have employed surface modifications that mimic the extracellular matrix. Strikingly absent is the immobilization of cell‐surface ligands to the biomaterial surface. One cell‐to‐cell signaling pathway that has been shown to regulate tissue development and stem cell fate is the Notch pathway. Recently, the Notch signaling pathway was identified as a key regulator of epithelial differentiation. Utilizing this knowledge, we applied an affinity immobilization scheme designed to attach and orient the Notch ligand, Jagged‐1, in an active conformation on a biomaterial surface. When epithelial stem cells were plated on the bound ligand, the Notch/CBF‐1 signaling pathway was stimulated and the cells upregulated both intermediate‐ and late‐stage differentiation markers. In addition, the ligand promoted tight clustering and extensive stratification. Soluble Jagged‐1 showed no Notch/CBF‐1 signaling and very little, if any, cell differentiating activity. The high potency of bound Jagged‐1 suggests that modification of a surface with a Notch ligand presents a powerful method to control stem cell differentiation at the cell–biomaterial interface. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Simulation of phase separation in alcohol/water mixtures using two‐body force field and standard molecular dynamics
Authors: Ferrari E. S. , Burton R. C. , Davey R. J. , Gavezzotti A.
Published: June 2006

Standard molecular dynamics simulations have been carried out on pure alcohols and alcohol/water mixtures. A simple atom–atom force field consisting of Lennard–Jones potentials plus coulombic terms over atomic point charges, but without explicit polarization terms, has been specifically fitted to reproduce several experimental properties of the pure alcohols, and has been used for mixtures by developing combination rules with the TIP3P water model. Densities, enthalpies of vaporization, radial distribution functions, self‐diffusion coefficients, and rotational correlation functions of the pure alcohols are well reproduced and compare favorably with those from more sophisticated force fields. Some key aspects of the phase behaviour are correctly reproduced by the molecular dynamics simulation, showing a distinct demixing process for the n‐butanol/water mixture as opposed to the stability of the t‐butanol/water mixtures. The results demonstrate the ability of a molecular dynamics simulation, even in its standard form and with easily accessible time ranges, but with a carefully optimized force field, to simulate and, to a certain extent, predict the properties of binary mixtures. © 2006 Wiley Periodicals, Inc. J Comput Chem 27: 1211–1219, 2006
Virtual biopsy of the joint tissues using near‐infrared, reflectance confocal microscopy. A pilot study
Authors: Campo‐Ruiz Vanessa , Patel Dinesh , Anderson R. Rox , Delgado‐Baeza Emilio , González Salvador
Published: June 2006

Standard noninvasive imaging techniques applied to joints provide gross morphological features, insufficient for assessing histological detail. On the other hand, biopsying is invasive, time consuming, and may involve unwanted processing artifacts. Near‐infrared reflectance confocal microscopy is a technique that allows serial, high‐resolution optical sectioning through intact tissues without employing exogenous fluorescent stains. The aim of this work was to evaluate the potential utility of near‐infrared reflectance confocal microscopy for providing immediate histological information on meniscus, articular cartilage, epiphyseal plate, bone, muscle, and tendon. Images from near‐infrared reflectance confocal microscopy were compared with mirror routine histology sections. Characteristic architectural features were readily visualized in the three dimensions of space. Additionally, the use of experimental contrast agents highlighted the localization of nuclei. Limitations include penetration depth and minor optical artifacts. In conclusion, near‐infrared reflectance confocal microscopy is a useful technique for immediate, nondestructive, serial “virtual” sectioning through intact tissues, being thus a potential adjunct to current imaging techniques in orthopedics. Microsc. Res. Tech., 2006. © 2006 Wiley‐Liss, Inc.
Rank‐tolerance graph classes
Authors: Golumbic Martin Charles , Jamison Robert E.
Published: June 2006

In this article we introduce certain classes of graphs that generalize
ϕ‐tolerance chain graphs. In a rank‐tolerance representation of a graph, each vertex is assigned two parameters: a rank, which represents the size of that vertex, and a tolerance which represents an allowed extent of conflict with other vertices. Two vertices are adjacent if and only if their joint rank exceeds (or equals) their joint tolerance. This article is concerned with investigating the graph classes that arise from a variety of functions, such as min, max, sum, and prod (product), that may be used as the coupling functions ϕ and ρ to define the joint tolerance and the joint rank. Our goal is to obtain basic properties of the graph classes from basic properties of the coupling functions.

We prove a skew symmetry result that when either ϕ or ρ is continuous and weakly increasing, the (ϕ,ρ)‐representable graphs equal the complements of the (ρ,ϕ)‐representable graphs. In the case where either ϕ or ρ is Archimedean or dual Archimedean, the class contains all threshold graphs. We also show that, for min, max, sum, prod (product) and, in fact, for any piecewise polynomial ϕ, there are infinitely many split graphs which fail to be representable.

In the reflexive case (where ϕ = ρ), we show that if ϕ is nondecreasing, weakly increasing and associative, the class obtained is precisely the threshold graphs. This extends a result of Jacobson, McMorris, and Mulder [10] for the function min to a much wider class, including max, sum, and prod.

We also give results for homogeneous functions, powers of sums, and linear combinations of min and max. © 2006 Wiley Periodicals, Inc. J Graph Theory
The generalized acyclic edge chromatic number of random regular graphs
Authors: Gerke Stefanie , Greenhill Catherine , Wormald Nicholas
Published: June 2006

The r‐acyclic edge chromatic number of a graph is defined to be the minimum number of colors required to produce an edge coloring of the graph such that adjacent edges receive different colors and every cycle C has at least min(|C|, r) colors. We show that (r − 2)d is asymptotically almost surely (a.a.s.) an upper bound on the r‐acyclic edge chromatic number of a random d‐regular graph, for all constants r ≥ 4 and d ≥ 2. © 2006 Wiley Periodicals, Inc. J Graph Theory 53: 101–125, 2006
Correlation between the bone marrow blood perfusion and lipid water content on the lumbar spine in female subjects
Authors: Chen Wei‐Tsung , Shih Tiffany Ting‐Fang
Published: June 2006

Purpose

To assess the marrow lipid water ratio (LWR) and spectral line width (LW) of lumbar vertebra by proton MR spectroscopy (1H MRS) and correlate with the marrow blood perfusion (MBP) by contrast‐enhanced dynamic MRI (dMRI) in female subjects.

Materials and Methods

A total of 50 female subjects were included. Single‐voxel 1H MRS was measured at the L3 vertebrae. In the dMRI study, the maximum enhancement percentage (Emax) and enhancement slope were calculated from time‐intensity curves. Pearson's correlation was calculated to explore the association of 1H MRS, age, and perfusion parameters. Partial correlation was then used to control confounder effect.

Results

LWR was negatively correlated with Emax (r = –0.72; P < 0.0001), but positively correlated with age (r = 0.63; P < 0.0001). Lipid LW was negatively correlated with age (r = –0.33; P <0.05), but positively correlated with Emax (r = 0.4; P < 0.05). After adjusting for the age effect by partial correlation, marrow LWR still negatively correlated with Emax (r = –0.63; P < 0.0001). After adjusting for the Emax effect, marrow LWR still positively correlated with age (r = 0.37; P < 0.05).

Conclusion

After controlling the age factor, the LWR and water LW has significant negative correlation with vertebral BMP. Further investigation is needed to explore the relationship between bone marrow fat metabolism and angiogenesis. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.
Passive catheter visualization in magnetic resonance–guided endovascular therapy using multicycle projection dephasers
Authors: Draper Jonathan N. , Lauzon M. Louis , Frayne Richard
Published: June 2006

Purpose

To improve upon the conventional projection dephaser (PD) method of background suppression and evaluate the use of multicycle projection dephasers to improve catheter conspicuity in background‐suppressed MR images.

Materials and Methods

Passive visualization of endovascular catheters in MR images is compared using two background suppression techniques: 1) the conventional PD method and 2) the multicycle PD method. Contrast‐filled 4‐French (1.3 mm) catheters were imaged in homogeneous and heterogeneous phantoms, and in the common carotid artery of a canine using a modified spoiled gradient echo imaging sequence. We used catheter‐to‐background contrast (ranging from –100% to 100%) as the metric to compare background suppression techniques.

Results

In the homogeneous and heterogeneous phantoms, the contrast was –6.9% (catheter darker than background) and 15.0%, respectively, using the conventional PD method, and 50.6% and 44.0%, respectively, using the multicycle PD method. In the canine carotid artery, the contrast was –3.1% using the conventional PD method and 53.0% using the multicycle PD method.

Conclusion

This work shows that multicycle projection dephasers improve catheter conspicuity over the conventional PD method. The multicycle PD method has potential for use in guiding endovascular procedures. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.
Discrepancy‐based adaptive regularization for GRAPPA reconstruction
Authors: Qu Peng , Wang Chunsheng , Shen Gary X.
Published: June 2006

Purpose

To develop a novel regularization method for GRAPPA by which the regularization parameters can be optimally and adaptively chosen.

Materials and Methods

In the fit procedures in GRAPPA, the discrepancy principle, which chooses the regularization parameter based on a priori information about the noise level in the autocalibrating signals (ACS), is used with the truncated singular value decomposition (TSVD) regularization and the Tikhonov regularization, and its performance is compared with the singular value (SV) threshold method and the L‐curve method, respectively by axial and sagittal head imaging experiments.

Results

In both axial and sagittal reconstructions, normal GRAPPA reconstruction results exhibit a relatively high level of noise. With discrepancy‐based choices of parameters, regularization can improve the signal‐to‐noise ratio (SNR) with only a very modest increase in aliasing artifacts. The L‐curve method in all of the reconstructions leads to overregularization, which causes severe residual aliasing artifacts. The 10% SV threshold method yields good overall image quality in the axial case, but in the sagittal case it also leads to an obvious increase in aliasing artifacts.

Conclusion

Neither a fixed SV threshold nor the L‐curve are robust means of choosing the appropriate parameters in GRAPPA reconstruction. However, with the discrepancy‐based parameter‐choice strategy, adaptively regularized GRAPPA can be used to automatically choose nearly optimal parameters for reconstruction and achieve an excellent compromise between SNR and artifacts. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.
Comparison between intravenous and intraarterial contrast injections for dynamic 3D MRI of liver tumors in the VX2 rabbit model
Authors: Larson Andrew C. , Rhee Thomas K. , Deng Jie , Wang Dingxin , Sato Kent T. , Salem Riad , Paunesku Tatjana , Woloschak Gayle , Mulcahy Mary F. , Li Debiao , Omary Reed A.
Published: June 2006

Purpose

To test the hypothesis that catheter‐directed intraarterial (IA) contrast agent injection increases tumor enhancement and conspicuity compared to intravenous (IV) injection.

Materials and Methods

Eight VX2 liver tumors were grown in five rabbits. After positioning a catheter in the hepatic artery, we performed 3D inversion recovery GRE MRI after IA and IV gadopentetate‐dimeglumine contrast injections at doses of 0.04 and 0.1 mmol/kg, respectively. Peak enhancement (signal‐to‐noise ratio (SNR)) and conspicuity (contrast‐to‐noise ratio (CNR)) were measured for each acquisition.

Results

The peak SNR and CNR were 21.7 ± 5.8 and 17.0 ± 4.8 (mean ± SD) after IA injection, and 16.9 ± 10.2 and 6.2 ± 2.6 after IV injection. The IA CNR was significantly greater than the IV CNR (P < 0.05), with a >60% increase in CNR for each tumor. For six of the eight tumors the IA SNR was greater than the IV SNR, but statistical significance was not achieved due to the small sample size of the study (P = 0.07).

Conclusion

We demonstrated the feasibility of using IA injection techniques to improve tumor conspicuity. This strategy could be employed to enhance the detection of small liver tumors or to conserve contrast agent in future MRI‐guided transcatheter liver therapies. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.
Analytical and semipreparative high performance liquid chromatography separation of stereoisomers of novel 3,4‐dihydropyrimidin‐4(3H)‐one derivatives on the immobilised amylose‐based Chiralpak IA chiral stationary phase
Authors: Cirilli Roberto , Ferretti Rosella , Gallinella Bruno , La Torre Francesco , Mai Antonello , Rotili Dante
Published: June 2006

Direct HPLC separation of stereoisomers of three novel 5‐methyl‐2‐(alkylthio)‐6‐(2,6‐difluorophenylalkyl)‐3,4‐dihydropyrimidin‐4(3H)‐ones endowed with antiviral and potential antiproliferative and morphological differentiation activity against melanoma cells was performed by using the new immobilised amylose‐based Chiralpak IA chiral stationary phase. Stereoselective conditions were achieved using normal phase eluents containing “non‐standard” solvents such as ethyl acetate, methyl tert‐butyl ether, or dichloromethane. In order to study the chiroptical properties of single stereoisomers, mg‐scale separations were performed on analytical and semipreparative size Chiralpak IA columns in combination with ethyl acetate‐based eluents.