bluuebunny/crossref_metadata_2025 huggingface dataset:
Emerging indirect and long‐term road salt effects on ecosystems
Authors: Findlay Stuart E.G. , Kelly Victoria R.
Published: March 2011

Widespread use of salts as deicing agents on roads has been perceived as a significant source of environmental and economic damage. Early studies focused on near‐road and short‐term effects where concentrations can exceed several grams per liter. Evidence is accumulating that the use of salts has significant effects over broader areas, longer time frames, and is affecting a range of ecological processes. Concentrations of NaCl can be elevated throughout an ecosystem to >100 mg Cl−/L, which may have nonlethal and possibly subtle effects on sensitive life stages of several organisms. NaCl seems subject to retention within terrestrial and aquatic ecosystems, thus prolonging the actual duration of exposure and leading to elevated warm‐season concentrations when reproduction may be occurring or other sensitive life stages are present. Many of the alternatives to NaCl reduce some of these negative effects, although are currently cost prohibitive for large‐scale use. Some techniques for managing application rates are improvements in technology, while others involve novel mixtures of organic compounds that may have new environmental consequences. The increasing evidence of these widespread and persistent environmental consequences must be brought into decisions on deicing procedures.
The environmental costs of mountaintop mining valley fill operations for aquatic ecosystems of the Central Appalachians
Authors: Bernhardt Emily S. , Palmer Margaret A.
Published: March 2011

Southern Appalachian forests are recognized as a biodiversity hot spot of global significance, particularly for endemic aquatic salamanders and mussels. The dominant driver of land‐cover and land‐use change in this region is surface mining, with an ever‐increasing proportion occurring as mountaintop mining with valley fill operations (MTVF). In MTVF, seams of coal are exposed using explosives, and the resulting noncoal overburden is pushed into adjacent valleys to facilitate coal extraction. To date, MTVF throughout the Appalachians have converted 1.1 million hectares of forest to surface mines and buried more than 2,000 km of stream channel beneath mining overburden. The impacts of these lost forests and buried streams are propagated throughout the river networks of the region as the resulting sediment and chemical pollutants are transmitted downstream. There is, to date, no evidence to suggest that the extensive chemical and hydrologic alterations of streams by MTVF can be offset or reversed by currently required reclamation and mitigation practices.
PHOTOCHEMISTRY OF ACETYLENIC KETONES IN MICELLAR SOLUTIONS AS STUDIED BY PRODUCT‐YIELD‐DETECTED ESR AND TRANSIENT ABSORPTION TECHNIQUES
Authors: Polyakov Nicolai E. , Okazaki Masaharu , Fujiwara Yoshihisa , Tanimoto Yoshifumi , Fukaya Haruhiko
Published: March 2011

The electron spin resonance (ESR) spectra of the transient radical pairs in the photoreduction of 1,5‐diphenyl‐1,4‐pentadiyn‐3‐one (I) and 1,3‐diphenyl‐2‐propyn‐1‐one (II) in sodium dodecyl sulfate (SDS) micellar solutions have been obtained by using the product‐yield‐detected ESR (PYESR) technique. The PYESR spectra, detected by tracing the microwave effect on the spin‐adduct yield as functions of the magnetic field, show the ESR spectra of the ketyl radical of the ketone and SDS radical as the components of the radical pairs. In addition, the growth and the decay processes of the radical pair were observed through detecting the effect of microwave pulse as functions of the delay period between a laser pulse and the off and on time, respectively, of a microwave pulse. The absorption spectra of transient species have also been obtained by using the laser flash photolysis technique. Through the analysis of these data and molecular orbital calculations, the role of acetylenic groups in the photoreactivity of acetylenic ketones is discussed.
MECHANISM OF PHOTOOXYGENATION OF THE CD (II) COMPLEX OF PYROPHEOPHORBIDE A METHYL ESTER
Authors: Curty Christophe , Engel Norbert , Iturraspe José , Gossauer Albert
Published: March 2011

Photooxygenation of (pyropheophorbidato a methyl ester)cadmium (II) was studied using 18,18O2 labeling of the molecular oxygen required for cleavage of the macrocycle. After reductive demetallation of the primary oxidation product (4,5‐dioxo‐4,5‐secopyropheophorbidato a methyl ester)cadmium (II), the isotope content of formylbilinone 4a was analyzed by repeated‐scan fast atom bombardment mass spectrometry. Comparison of the spectroscopic data of the labeled pigment 4a with the statistical probabilities of18 O isotope incorporation calculated for four possible reaction mechanisms clearly proves that photooxidative ring cleavage occurred by the one‐molecule mechanism, i.e. the terminal oxygen atoms of 4a were derived from one oxygen molecule. Furthermore, a study of the exchange of the18 O‐labeled atoms revealed that no exchange occurs within the pH 4.5–9.5 range. In stronger alkaline or acidic solutions, only the oxygen atom of the formyl group is exchanged. Hydrolysis of the methyl ester group of 4a was achieved, without loss of the18 O label on the formyl group, at pH 7.2 in the presence of pig liver esterase.
PHOTO‐CIDNP STUDY OF PYRIMIDINE DIMER SPLITTING I: REACTIONS INVOLVING PYRIMIDINE RADICAL CATION INTERMEDIATES
Authors: Pouwels Petra J. W. , Kaptein Robert , Hartman Rosemarie F. , Rose Seth D.
Published: March 2011

The light‐induced splitting of pyrimidine dimers was studied using the electron acceptor anthraquinone‐2‐sulfonate (AQS) as a photosensitizer. To this end, photochemically induced dynamic nuclear polarization (photo‐CIDNP) experiments were performed on a series of pyrimidine monomers and dimers. The CIDNP spectra demonstrate the existence of both the dimer radical cation, which is formed by electron transfer from the dimer to the photoexcited sensitizer AQS*, and its dissociation product, the monomer radical cation. In spectra of 1,1′‐trimethylene bridged cis,syn pyrimidine dimers, polarization is observed that originates from a spin‐sorting process in the dimer radical pair. This points to a relatively long lifetime of the dimer radical cation involved, which is presumably due to stabilization by the trimethylene bridge. Polarization originating from a dimer radical pair is detected in the spectrum of trans,anti (1,3‐dimethyluracil) dimer as well. The spectra of the bridged pyrimidines also demonstrate the reversibility of the dissociation of dimer radical cation into monomer radical cation, which is concluded from the observation of polarization in the dimer as a result of spin sorting in the monomer radical pair.
EFFECTS OF SHORT PULSES OF BLUE LIGHT ON THE ALKALINIZATION ASSOCIATED WITH THE UPTAKE OF NO3−AND CL−BY THE GREEN ALGAMONORAPHIDIUM BRAUNIIAND RELATED ACTION SPECTRA
Authors: Witt Federico G. , Aparicio Pedro J.
Published: March 2011

InMonoraphidium braunii, uptake of NO3−, NO2−and Cl−is associated with proton transport and triggered by blue light (BL). Only 10 s after cells able to reduce NO3−to NH4+were irradiated with continuous, low‐fluence BL in the presence of NO3−, an alkalinization of the medium began and only became interrupted by switching off the BL with a 60–90 s time lag. With 30 s BL pulses, the NO3−‐dependent alkalinization lasted 3–5 min until it stopped. When the cells were exposed to continuous BL in the presence of Cl−, the alkalinization also started within 10 s but lasted only 3 min. After that, the pH remained constant and decreased when the BL was switched off. With 30 s BL pulses, the Cl−‐dependent alkalinization lasted 3 min and then decreased to its initial value. The NO3−‐dependent alkalinization shown by cells unable to reduce NO3−to NH4+was similar to that observed in the presence of Cl−. These alkalinization rates fit the Bunsen‐Roscoe reciprocity law. With 2 s pulses of high‐fluence BL, the delay time of the NO3‐ or Cl−‐dependent alkalinizations was only 2 s, one of the fastest BL responses reported so far. The action spectra for Cl−and NO3−uptakes proved to be very similar and matched the absorption spectra of flavins, including the 267 nm peak.
DUAL ROLE OF MELANINS AND MELANIN PRECURSORS AS PHOTOPROTECTIVE AND PHOTOTOXIC AGENTS: INHIBITION OF ULTRAVIOLET RADIATION‐INDUCED LIPID PEROXIDATION
Authors: Schmitz Stefan , Thomas Panakkezhum D. , Allen Theresa M. , Poznansky Mark J. , Jimbow Kowichi
Published: March 2011

Ultraviolet radiation (UVR) is one of the risk factors for skin cancer and the main inducer of melanin pigmentation, the major protective mechanism of mammalian skin against radiation damage. The melanin pigments, eumelanin and pheomelanin, are likely to be important in protection against UVR, but their precursors are generally considered as phototoxic. The available data suggest DNA damage as the mechanism of phototoxicity. However, the effect of melanin precursors on membrane damage through lipid peroxidation, another important and probably more relevant (from the point‐of‐view of the melanosomal confinement of these molecules) mechanism of phototoxicity, is not known. As a model system for UVR–melanin–membrane interactions, we irradiated liposomes in the presence of eumelanin, pheomelanin and two of their major precursors, 5,6‐dihydroxyindole (DHI) and 5‐S‐cysteinyldopa (SCD). The presence of the two melanin precursors substantially reduced the formation of lipid peroxidation products resulting from UVR exposure. The antioxidant activity of the melanin precursors was diminished under strong prooxidant conditions (presence of Fe3+). These results suggest that melanin precursors may have an important role in the protection of skin against the harmful effects of UVR including photocarcinogenesis.
Extended long‐term outcomes of cataract surgery
Authors: Mönestam Eva I. , Lundqvist Britta
Published: March 2011

Purpose:  To longitudinally report the changes in visual acuity (VA) and subjective visual function, 10 years after cataract surgery.

Methods:  This population‐based prospective study reviewed 335 patients (85% of survivors) who underwent cataract surgery during a 1‐year period in 1997–98, 289 of whom were also re‐examined. The patients underwent a routine eye examination and answered the same visual function questionnaire (VF‐14), preoperatively, 4 months postoperatively, 5 years and 10 years after surgery.

Results:  Ten years after surgery, the best corrected VA (BCVA) of the operated eye had deteriorated to a median of 0.06 (logMAR) (Snellen acuity: 20/23) from 0.046 (logMAR) (20/22) postoperatively (p = 0.001). More than two‐thirds of the patients had <0.1 logMAR units worsening of BCVA compared with postoperatively. Approximately half of the patients had no deterioration in subjective visual function, and 77% had 10 points decline or less. Twelve per cent of the patients (42/335) had a worsening of more than 30 points. Effect size was calculated for the VF‐14 total score at all three occasions of follow‐up after surgery and was largest approximately 4 months postoperatively. Long‐time follow‐up of 10 years shows still moderate effect size.

Conclusion:  These results confirm the effectiveness of cataract extraction, offering good long‐term visual rehabilitation for the majority of the patients. The most common cause for large functional loss after 10 years is age‐related macular degeneration.
Design of Compliant Thermal Actuators Using Structural Optimization Based on the Level Set Method
Authors: Yamada Takayuki , Yamasaki Shintaro , Nishiwaki Shinji , Izui Kazuhiro , Yoshimura Masataka
Published: March 2011

Compliant mechanisms are designed to be flexible to achieve a specified motion as a mechanism. Such mechanisms can function as compliant thermal actuators in micro-electromechanical systems by intentionally designing configurations that exploit thermal expansion effects in elastic material when appropriate portions of the mechanism structure are heated or are subjected to an electric potential. This paper presents a new structural optimization method for the design of compliant thermal actuators based on the level set method and the finite element method (FEM). First, an optimization problem is formulated that addresses the design of compliant thermal actuators considering the magnitude of the displacement at the output location. Next, the topological derivatives that are used when introducing holes during the optimization process are derived. Based on the optimization formulation, a new structural optimization algorithm is constructed that employs the FEM when solving the equilibrium equations and updating the level set function. The re-initialization of the level set function is performed using a newly developed geometry-based re-initialization scheme. Finally, several design examples are provided to confirm the usefulness of the proposed structural optimization method.
Thermal Hot Spot and Corrosion Damage in Conical Pressure Components
Authors: Adibi-Asl R. , Seshadri R.
Published: March 2011

Structural integrity of an in-service component containing damage such as corrosion and thermal hot spot has to be evaluated regularly so as to certify the acceptance and safety of continued service of the component. In this paper, limit load solutions of a damaged conical shell, particularly local wall thinning and thermal hot spot, is investigated. The derived solutions are based on identifying the regions in the damaged component that directly participate in the plastic action (kinematically active). The concepts of reference volume and decay length are employed to identify the kinematically active regions in the damaged conical shell. The different solutions proposed in this paper are compared with the elastic-plastic finite element analysis. The results indicate that proposed solutions can be used with acceptable accuracy to make integrity assessment decisions.
Explicit Inversion of Stodola’s Area-Mach Number Equation
Authors: Majdalani Joseph , Maicke Brian A.
Published: March 2011

Stodola’s area-Mach number relation is one of the most widely used expressions in compressible flow analysis. From academe to aeropropulsion, it has found utility in the design and performance characterization of numerous propulsion systems; these include rockets, gas turbines, microcombustors, and microthrusters. In this study, we derive a closed-form approximation for the inverted and more commonly used solution relating performance directly to the nozzle area ratio. The inverted expression provides a computationally efficient alternative to solutions based on traditional lookup tables or root finding. Here, both subsonic and supersonic Mach numbers are obtained explicitly as a function of the area ratio and the ratio of specific heats. The corresponding recursive formulations enable us to specify the desired solution to any level of precision. In closing, a dual verification is achieved using a computational fluid dynamics simulation of a typical nozzle and through Bosley’s formal approach. The latter is intended to confirm the truncation error entailed in our approximations. In this process, both asymptotic and numerical solutions are compared for the Mach number and temperature distributions throughout the nozzle.
A Nonlinear Three-Dimensional Coupled Fluid-Sediment Interaction Model for Large Seabed Deformation
Authors: Nakamura Tomoaki , Yim Solomon C.
Published: March 2011

A nonlinear three-dimensional two-way coupled fluid-sediment interaction model is developed in this study. The model is composed of a generalized Navier–Stokes solver (GNS) with a volume of fluid module for air-water interface tracking and a sediment transport module (STM) for fluid-sediment interface tracking. The GNS model is based on the finite difference method with a turbulent stress model of large-eddy simulation to compute incompressible viscous multiphase flows. The STM is used to compute nonlinear sediment bed profile change due to bed-load sediment transport. A two-way coupling scheme connecting GNS with STM is implemented at each time step to ensure the fluid-sediment interaction. For validation, the fluid-sediment interaction model is applied to predict cross-shore profile change of a sloping beach due to breaking solitary waves, and the resulting predictions are examined and compared with the measured data from a set of hydraulic tests. It is found that the fluid-sediment interaction model predicts reasonably well the sediment transport and the resulting beach profile change. The sensitivity of model parameters involving the sediment transport to the beach profile change is analyzed. Finally, the fluid-sediment interaction model is applied to predict local scour in front of a quay wall due to a jet flow to demonstrate its applicability to general three-dimensional problems.
Effect of Turbulent Prandtl Number on Convective Heat Transfer to Turbulent Flow of a Supercritical Fluid in a Vertical Round Tube
Authors: Mohseni Mahdi , Bazargan Majid
Published: March 2011

A two-dimensional numerical model is developed to study the effect of the turbulent Prandtl number Prt on momentum and energy transport in a highly variable property flow of supercritical fluids in a vertical round tube. Both regimes of enhanced and deteriorated heat transfer have been investigated. The equations of the Prt leading to the best agreement with the experiments in either regime of heat transfer were specified. The results of this study show that the increase in the Prt causes the heat transfer coefficients to decrease. When the buoyancy force increases, a better agreement with the experimental data is reached if values lower than 0.9 are used for the Prt. A decrease in the Prt values results in an increase in turbulent activities. From the effect that the Prt has on heat transfer coefficients, it may be deduced that the buoyancy effects in the upward flow of a supercritical fluid lead to the decrease in the Prt value and hence to the increase in the heat transfer coefficients. Furthermore, the value of the Prt in the laminar viscous sublayer as expected does not have a significant effect on heat transfer rate. The effect of the turbulence model on the extent to which the Prt influences the rate of heat transfer is also examined. The results obtained are shown to be valid regardless of the turbulence model used.
Isoconstrained Parallel Generators of Schoenflies Motion
Authors: Lee Chung-Ching , Hervé Jacques M.
Published: March 2011

Based on the Lie-group-algebraic properties of the displacement set, the 4DOF primitive generators of the Schoenflies motion termed X-motion for brevity are briefly recalled. An X-motion includes 3DOF spatial translation and any 1DOF rotation provided that the axes are parallel to a given direction. The serial concatenation of two generators of 4DOF X-motion produces a 5DOF motion called double Schoenflies motion or X-X-motion for brevity, which includes 3DOFs of translations and any 2DOFs of rotations if the axes are parallel to two independent vectors. This is established using the composition product of two Lie subgroups of X-motion. All possible 5DOF serial chains with distinct general architectures for the generation of X-X-motion are comprehensively introduced in the beginning. The parallel setting between a fixed base and a moving platform of two 5DOF X-X limbs, under particular geometric conditions, makes up a 4DOF isoconstrained parallel generator (abbreviated as IPG-X) of a Schoenflies motion set. “Isoconstrained” is synonymous with “nonoverconstrianed,” and the corresponding chains are trivial chains of the 6D group of general 6DOF motions and can move in the presence of manufacturing errors. Moreover, related families of IPG-Xs are also deducted by using the reordering or the commutation of the factor method, which yields more 5D subsets of displacements containing also the X-motion of the end effector. In that way, several novel general-type architectures of 4DOF parallel manipulators with potential applications are synthesized systematically in consideration of the actuated pairs near the fixed base.
Independent quality assurance of a helical tomotherapy machine using the dose magnifying glass
Authors: Wong J. H. D. , Hardcastle N. , Tomé W. A. , Bayliss A. , Tolakanahalli R. , Lerch M. L. F. , Petasecca M. , Carolan M. , Metcalfe P. , Rosenfeld A. B.
Published: March 2011

Purpose:

Helical tomotherapy is a complex delivery technique, integrating CT image guidance and intensity modulated radiotherapy in a single system. The integration of the CT detector ring on the gantry not only allows patient position verification but is also often used to perform various QA procedures. This convenience lacks the rigor of a machine‐independent QA process.

Methods:

In this article, a Si strip detector, known as the Dose Magnifying Glass (DMG), was used to perform machine‐independent QA measurements of the multileaf collimator alignment, leaf open time threshold, and leaf fluence output factor (LFOF).

Results:

The DMG measurements showed good agreements with EDR2 film for the MLC alignment test while the CT detector agrees well with DMG measurements for leaf open time threshold and LFOF measurements. The leaf open time threshold was found to be approximately 20 ms. The LFOF measured with the DMG agreed within error with the CT detector measured LFOF.

Conclusions:

The DMG with its 0.2 mm spatial resolution coupled to TERA ASIC allowed real‐time high temporal resolution measurements of the tomotherapy leaf movement. In conclusion, DMG was shown to be a suitable tool for machine‐independent QA of a tomotherapy unit.
On the use of the MLC dosimetric leaf gap as a quality control tool for accurate dynamic IMRT delivery
Authors: Mei Xiangyang , Nygren Ian , Villarreal‐Barajas J. Eduardo
Published: March 2011

Purpose:

MLC leaf gap consistency is critical for the accurate delivery of dynamic IMRT plans. It is estimated that a systematic MLC leaf gap change of 0.6 mm will result in a 2% change to the equivalent uniform dose to a clinical target volume for a typical head and neck sliding window (SW) IMRT plan. The aim of this work is to use the measured dosimetric leaf gap (DLG) to verify the dosimetric reproducibility of dynamically delivered SW IMRT plans. This study focuses on Varian linacs equipped with the 120 Millennium MLC and the Eclipse™ treatment planning system (TPS), but can be extended to other linac/MLC/TPS combination.

Methods:

An ionization chamber, a diode array, and an electronic portal imaging device (EPID) were used to assess the DLG in zero (central axis), one, and two dimensions, respectively. The DLG for zero and two dimensions was derived from measurements of SW fields of decreasing width (2, 1.5, 1, and 0.5 cm). The DLG in one dimension was measured directly from a single SW sweeping across a linear diode array. This one‐dimensional DLG measurement was based on the full width at half maximum (FWHM) of the dose rate versus time spectrum.

Results:

The DLG derived from ion chamber measurements at central axis agrees to within 0.1 mm, with the DLG measured directly from the FWHM of dose rate versus time spectrum. The measured DLG depends on the control points used for the MLC SW fields. When two control points were used, the DLG measured at central axis showed an increase of 0.6 mm with respect to the same measurements performed using three or more control points. The two‐dimensional distribution of DLG obtained using the EPID identified leaf gap errors as small as ±0.2 mm in isolated areas away from central axis.

Conclusions:

Comprehensive measurements of the DLG in 0D, 1D, and 2D provide an accurate assessment of DLG value required during TPS commissioning. These DLG measurements can also be used as a quality control tool to quantify changes of the MLC calibration and leaf gap consistency, which is critical for the accurate delivery of dynamically delivered SW IMRT plans.
Human Pluripotent Stem Cells: Decoding the Naïve State
Authors: Li Wenlin , Ding Sheng
Published: March 2011

Human stem cells exist in functionally distinct states that must be deciphered before these versatile reagents can be used to transform medicine.
Fetal DNA: A Needle in the Haystack
Authors: Evans-Molina Carmella
Published: March 2011

A fetal epigenetic footprint in mothers’ blood paves the way for noninvasively diagnosing Down’s syndrome.
Molecular Cancer Screening Comes Alive
Authors: Lin Richard J.
Published: March 2011

Epigenetic signatures help to predict risk of bladder cancer.
Elongin B-Mediated Epigenetic Alteration of Viral Chromatin Correlates with Efficient Human Cytomegalovirus Gene Expression and Replication
Authors: Hwang Jiwon , Saffert Ryan T. , Kalejta Robert F.
Published: March 2011

Elongins B and C are members of complexes that increase the efficiency of transcriptional elongation by RNA polymerase II (RNAPII) and enhance the monoubiquitination of histone H2B, an epigenetic mark of actively transcribed genes. Here we show that, in addition to its role in facilitating transcription of the cellular genome, elongin B also enhances gene expression from the double-stranded DNA genome of human cytomegalovirus (HCMV), a pathogenic herpesvirus. Reducing the level of elongin B by small interfering RNA- or short hairpin RNA-mediated knockdown decreased viral mRNA expression, viral protein accumulation, viral DNA replication, and infectious virion production. Chromatin immunoprecipitation analysis indicated viral genome occupancy of the elongating form of RNAPII, and monoubiquitinated histone H2B was reduced in elongin B-deficient cells. These data suggest that, in addition to the previously documented epigenetic regulation of transcriptional initiation, HCMV also subverts cellular elongin B-mediated epigenetic mechanisms for enhancing transcriptional elongation to enhance viral gene expression and virus replication.

IMPORTANCE
The genetic and epigenetic control of transcription initiation at both cellular and viral promoters is well documented. Recently, the epigenetic modification of histone H2B monoubiquitination throughout the bodies of cellular genes has been shown to enhance the elongation of RNA polymerase II-initiated transcripts. Mechanisms that might control the elongation of viral transcripts are less well studied. Here we show that, as with cellular genes, elongin B-mediated monoubiquitination of histone H2B also facilitates the transcriptional elongation of human cytomegalovirus genes. This and perhaps other epigenetic markings of actively transcribed regions may help in identifying viral genes expressed during
in vitro
latency or during natural infections of humans. Furthermore, this work identifies a novel, tractable model system to further study the regulation of transcriptional elongation in living cells.
Impact of a smoking ban in public places: a rapid assessment in the Seychelles: Table 1
Authors: Viswanathan Bharathi , Plumettaz Chloé , Gedeon Jude , Bovet Pascal
Published: March 2011

Background

We assessed the impact of a smoking ban in hospitality venues in the Seychelles 9 months after legislation was implemented.

Methods

Survey officers observed compliance with the smoking ban in 38 most popular hospitality venues and administered a structured questionnaire to two customers, two workers and one manager in each venue.

Results

Virtually no customers or workers were seen smoking in the indoor premises. Patrons, workers and managers largely supported the ban. The personnel of the hospitality venues reported that most smokers had no difficulty refraining from smoking. However, a third of workers did not systematically request customers to stop smoking and half of them did not report adequate training. Workers reported improved health. No substantial change in the number of customers was noted.

Conclusion

A ban on public smoking was generally well implemented in hospitality venues but some less than optimal findings suggest the need for adequate training of workers and strengthened enforcement measures. The simple and inexpensive methodology used in this rapid survey may be a useful approach to evaluate the implementation and impact of clean air policy in low and middle-income countries.
The cyanobacterial bicarbonate transporter BicA: its physiological role and the implications of structural similarities with human SLC26 transportersThis paper is one of a selection of papers published in a Special Issue entitled CSBMCB 53rd Annual Meeting — Membrane Proteins in Health and Disease, and has undergone the Journal’s usual peer review process.
Authors: Price G. Dean , Howitt Susan M.
Published: March 2011

The cyanobacterial Na+-dependent HCO3–transporter BicA is a member of the ubiquitous and important SulP/SLC26 family of anion transporters found in eukaryotes and prokaryotes. BicA is an important component of the cyanobacterial CO2concentrating mechanism, an adaptation that contributes to cyanobacteria being able to achieve an estimated 25% of global primary productivity, largely in the oceans. The human SLC26 members are involved in a range of key cellular functions involving a diverse range of anion transport activities including Cl–/HCO3–, I–/HCO3–, and SO42–/HCO3–exchange; mutations in SLC26 members are known to be associated with debilitating diseases such as Pendred syndrome, chondrodysplasias, and congenital chloride diarrhoea. We have recently experimentally determined the membrane topology of BicA using the phoA–lacZ reporter system and here consider some of the extrapolated implications for topology of the human SLC26 family and the Sultr plant sulphate transporters.
Structural analysis of the Na+/H+ exchanger isoform 1 (NHE1) using the divide and conquer approachThis paper is one of a selection of papers published in a Special Issue entitled CSBMCB 53rd Annual Meeting — Membrane Proteins in Health and Disease, and has undergone the Journal’s usual peer review process.
Authors: Lee Brian L. , Sykes Brian D. , Fliegel Larry
Published: March 2011

The sodium/proton exchanger isoform 1 (NHE1) is an ubiquitous plasma membrane protein that regulates intracellular pH by removing excess intracellular acid. NHE1 is important in heart disease and cancer, making it an attractive therapeutic target. Although much is known about the function of NHE1, current structural knowledge of NHE1 is limited to two conflicting topology models: a low-resolution molecular envelope from electron microscopy, and comparison with a crystal structure of a bacterial homologue, NhaA. Our laboratory has used high-resolution nuclear magnetic resonance (NMR) spectroscopy to investigate the structures of individual transmembrane helices of NHE1 — a divide and conquer approach to the study of this membrane protein. In this review, we discuss the structural and functional insights obtained from this approach in combination with functional data obtained from mutagenesis experiments on the protein. We also compare the known structure of NHE1 transmembrane segments with the structural and functional insights obtained from a bacterial sodium/proton exchanger homologue, NhaA. The structures of regions of the NHE1 protein that have been determined have both similarities and specific differences to the crystal structure of the NhaA protein. These have allowed insights into both the topology and the function of the NHE1 protein.
Interactions of mouse glycophorin A with the dRTA-related mutant G719D of the mouse Cl–/HCO3–exchanger Ae1This paper is one of a selection of papers published in a Special Issue entitled CSBMCB 53rd Annual Meeting — Membrane Proteins in Health and Disease, and has undergone the Journal’s usual peer review process.
Authors: Stewart Andrew K. , Chebib Fouad T. , Akbar Syed W. , Salas Maria J. , Sonik Rajan A. , Shmukler Boris E. , Alper Seth L.
Published: March 2011

The AE1 mutation G701D, associated with recessive distal renal tubular acidosis (dRTA), produces only minimal erythroid phenotype, reflecting erythroid-specific expression of stimulatory AE1 subunit glycophorin A (GPA). GPA transgene expression could theoretically treat recessive dRTA in patients and in mice expressing cognate Ae1 mutation G719D. However, human (h) GPA and mouse (m) Gpa amino acid sequences are widely divergent, and mGpa function in vitro has not been investigated. We therefore studied in Xenopus oocytes the effects of coexpressed mGpa and hGPA on anion transport by erythroid (e) and kidney (k) isoforms of wild-type mAe1 (meAe1, mkAe1) and of mAe1 mutant G719D. Coexpression of hGPA or mGpa enhanced the function of meAe1 and mkAe1 and rescued the nonfunctional meAe1 and mkAe1 G719D mutants through increased surface expression. Progressive N-terminal truncation studies revealed a role for meAe1 amino acids 22–28 in GPA-responsiveness of meAe1 G719D. MouseN-cyto/humanTMDand humanN-cyto/mouseTMDkAE1 chimeras were active and GPA-responsive. In contrast, whereas chimera mkAe1N-cyto/hkAE1 G701DTMDwas GPA-responsive, chimera hkAE1N-cyto/mkAe1 G719DTMDwas GPA-insensitive. Moreover, whereas the isolated transmembrane domain (TMD) of hAE1 G701D was GPA-responsive, that of mAe1 G719D was GPA-insensitive. Thus, mGpa increases surface expression and activity of meAe1 and mkAe1. However, the G719D mutation renders certain mAe1 mutant constructs GPA-unresponsive and highlights a role for erythroid-specific meAe1 amino acids 22–28 in GPA-responsiveness.
Mechanism of tumor resistance to cisplatin mediated by the copper transporter ATP7BThis paper is one of a selection of papers published in a Special Issue entitled CSBMCB 53rd Annual Meeting — Membrane Proteins in Health and Disease, and has undergone the Journal’s usual peer review process.
Authors: Dmitriev Oleg Y.
Published: March 2011

The Wilson disease protein (ATP7B) is a copper-transporting ATPase that is responsible for regulating copper homeostasis in human tissues. ATP7B is associated with cancer resistance to cisplatin, one of the most widely used anticancer drugs. This minireview discusses the possible mechanisms of tumor resistance to cisplatin mediated by ATP7B. Cisplatin binds to the N-terminal cytosolic domain of ATP7B, which contains multiple copper-binding sites. Active platinum efflux catalyzed by ATP7B is unlikely to significantly contribute to cisplatin resistance in vivo. Transient platinum sequestration in the metal-binding domain followed by transfer to an acceptor protein or a low molecular weight compound is proposed as an alternative mechanism of cisplatin detoxification in the cell.
Report on the Bicarbonate Transport Satellite Meeting at the 53rd Annual Meeting of the Canadian Society of Biochemistry, Molecular and Cellular Biology
Authors: Reithmeier Reinhart A.F. , Casey Joseph R.
Published: March 2011

The Bicarbonate Transport Meeting was held as a satellite meeting of the 53rd Annual Meeting of the Canadian Society of Biochemistry, Molecular and Cellular Biology (CSBMCB): Membrane Proteins in Health and Disease. The meeting covered the modern history of bicarbonate transporter proteins and brought together the major workers in the field. Ron Kopito recounted the story of the first determination of the amino acid sequence for a bicarbonate transporter, AE1/Band 3, 25 years earlier while working with Harvey Lodish at Harvard, while Tomohiro Yamaguchi and Teruhisa Hirai presented up-to-date data on AE1 structure obtained using electron crystallography. The meeting further spanned the spectrum of bicarbonate transporters, with sessions devoted to Cl–/HCO3– exchangers, Na+/HCO3– co-transporters, the link to carbonic anhydrase, and the SLC26 family of bicarbonate transporters expressed broadly in humans, yeast, and bacteria.
Physiological and Therapeutical Roles of Ginger and Turmeric on Endocrine Functions
Authors: Al-Suhaimi Ebtesam A. , Al-Riziza Noorah A. , Al-Essa Reham A.
Published: March 2011

The natural product ginger (Zingiber officinale) has active constituents gingerol, Shogaol and Zerumbone, while turmeric (Curcuma longa) contains three active major curcuminoids, namely, curcumin, demethoxycurcumin, and bisdemethoxycurcumin. They have the same scientific classification and are reported to have anti-inflammatory and many therapeutic effects. This article reviews the physiological and therapeutic effects of ginger and turmeric on some endocrine gland functions, and signal pathways involved to mediate their actions. With some systems and adipose tissue, ginger and turmeric exert their actions through some/all of the following signals or molecular mechanisms: (1) through reduction of high levels of some hormones (as: T4, leptin) or interaction with hormone receptors; (2) by inhibition of cytokines/adipokine expression; (3) acting as a potent inhibitor of reactive oxygen species (ROS)-generating enzymes, which play an essential role between inflammation and progression of diseases; (4) mediation of their effects through the inhibition of signaling transcription factors; and/or (5) decrease the proliferative potent by down-regulation of antiapoptotic genes, which may suppress tumor promotion by blocking signal transduction pathways in the target cells. These multiple mechanisms of protection against inflammation and oxidative damage make ginger and curcumin particularly promising natural agents in fighting the ravages of aging and degenerative diseases, and need to be paid more attention by studies.
Effects of Long-Term Tai Chi Practice on Balance and H-Reflex Characteristics
Authors: Guan Hongwei , Koceja David M.
Published: March 2011

The purpose of the present study was to examine the effects of long-term Tai Chi practice on postural balance and H-reflex. Sixteen healthy volunteers, eight with three or more years of experience in Tai Chi training (Tai Chi Group-TCG), and eight with no experience in Tai Chi training (Control Group-CG) participated in the study. Postural sways were measured under four experimental conditions: (1) Standing still with eyes open (EO); (2) Standing still with eyes closed (EC); (3) Standing and turning head to left and right with eyes open (EOT); and (4) Standing and turning head to left and right with eyes closed (ECT). Paired reflex depression (PRD) of the soleus muscle was measured under two conditions: supine and standing. Less significant postural sway was observed in the TCG than in the CG under four conditions including EO, EC, EOT, and ECT (p < 0.01). The TCG demonstrated 14.1%, 30.6%, 33.3% and 22.7% less postural sway, respectively. Significant PRD change from a supine to standing position was observed between TCG and CG (p < 0.05). A significant correlation between PRD change (from supine to standing) and years of Tai Chi practice was observed (r = 0.80, p < 0.05). The findings of this study support the positive effects of Tai Chi exercise on balance control under different conditions. Long-term Tai Chi exercisers also demonstrated different reflex modulation from a supine to standing position, and long-term Tai Chi practice may lead to a change of PRD modulation as neuroadaptation.
Hepatic PTP1B Expression Involvement in the Effects of Chinese Medicine Formula Xiao-Gao-Jiang-Zhuo Using an Obese Rat Model
Authors: Li Min , Chang Bai , Zhen Zhong , Qin Pei-Jie , Liu Wen-Ke , Tong Xiao-Lin
Published: March 2011

In this study, we investigated the effects of a Chinese herbal medicine formula Xiao-Gao-Jiang-Zhuo (XGJZ) in obese rats induced by a high-fat diet. Ten male rats in the normal group were fed with a standard diet. Another 50 male obese rats were induced by a 12-week high-fat diet feeding, and were randomly divided into five groups (n = 10 per group): the model group, the high-dose XGJZ group, the middle-dose XGJZ group, the low-dose XGJZ group, and the sibutramine group. After 14 weeks of treatment, body weight, abdominal fat, blood lipid and serum insulin level were measured, and the protein and gene expression of PTP1B in liver tissue was tested. Our data showed that the body weight of the high-dose and middle-dose groups and the sibutramine group had significant differences in comparison with the model group (p < 0.05), and all three dose groups had significantly reduced abdominal fat (p < 0.05). The triglyceride level of the three dose groups and the sibutramine group, and the total cholesterol level of the middle-dose group were all significantly reduced (p < 0.05). The serum insulin of the high-dose and middle-dose groups also decreased significantly (p < 0.05). The expression of hepatic PTP1B mRNA of the three dose groups decreased significantly in comparison with the model group (p < 0.05 or 0.01). The expression of hepatic PTP1B protein of the high-dose and middle-dose groups decreased significantly (p < 0.05). Our data suggested that XGJZ can modulate the body weight, abdominal fat and blood lipid in the obese rats, and this modulation might improve insulin resistance by inhibiting the PTP1B signal pathway.
MONOPOLE SHIFT IN ODD NEUTRON-RICH F ISOTOPES: A SHELL MODEL DESCRIPTION
Authors: SRIVASTAVA P. C. , MEHROTRA I.
Published: March 2011

Monopole shift in the proton states in odd neutron-rich F isotopes has been studied with neutron number changing from N = 10 to 20 for three different interactions. The variation of monopole shift point out towards appearance of shell closure at N = 14 and N = 16 and its disappearance at N = 20. Low lying states of odd F isotopes have also been calculated in the limited configuration space of sd shells for these interactions.
ENERGY AND MASS GENERATION
Authors: SIDHARTH B. G.
Published: March 2011

Modifications in the energy–momentum dispersion laws due to a noncommutative geometry, have been considered in recent years. We examine the oscillations of extended objects in this perspective and find that there is now a "generation" of energy.
β-DECAY OF KEY TITANIUM ISOTOPES IN STELLAR ENVIRONMENT
Authors: NABI JAMEEL-UN , BAKHADIR IRGAZIEV
Published: March 2011

Amongst iron regime nuclei, β-decay rates on titanium isotopes are considered to be important during the late phases of evolution of massive stars. The key β-decay isotopes during presupernova evolution were searched from available literature and a microscopic calculation of the decay rates were performed using the proton–neutron quasiparticle random phase approximation (pn-QRPA) theory. As per earlier simulation results, electron capture and β-decay on certain isotopes of titanium are considered to be important for the presupernova evolution of massive stars. Earlier the stellar electron capture rates and neutrino energy loss rates due to relevant titanium isotopes were presented. In this paper we finally present the β-decay rates of key titanium isotopes in stellar environment. The results are also compared against previous calculations. The pn-QRPA β-decay rates are bigger at high stellar temperatures and smaller at high stellar densities compared to the large scale shell model results. This study can prove useful for the core-collapse simulators.
MICROSCOPICAL ANALYSIS OF THE REACTION CROSS-SECTIONS OF 11Li+12C and 22C+12C ELASTIC SCATTERING
Authors: IBRAHEEM AWAD A.
Published: March 2011

Total reaction cross-sections of the two neutron halo nuclei 11Li and 22C elastic scattering from 12C target at E = 30–1000 MeV/nucleon have been analyzed using the eikonal phase shift based, for the first time, on the semi-phenomenological nucleon density. The obtained results reasonably agree with those of previous theoretical calculations as well as the corresponding experimental data.
LIFETIME OF 26S AND A LIMIT FOR ITS 2p DECAY ENERGY
Authors: FOMICHEV A. S. , MUKHA I. G. , STEPANTSOV S. V. , GRIGORENKO L. V. , LITVINOVA E. V. , CHUDOBA V. , EGOROVA I. A. , GOLOVKOV M. S. , GORSHKOV A. V. , GORSHKOV V. A. , KAMINSKI G. , KRUPKO S. A. , PARFENOVA YU. L. , SIDORCHUK S. I. , SLEPNEV R. S. , TER-AKOPIAN G. M. , WOLSKI R. , ZHUKOV M. V.
Published: March 2011

The unknown isotope 26 S , expected to decay by two-proton (2p) emission, was studied theoretically and searched experimentally. The structure of this nucleus was examined within the relativistic mean field (RMF) approach. A method for taking into account the many-body structure in the three-body decay calculations was developed. The results of the RMF calculations were used as an input for the three-cluster decay model optimized for the study of a possible 2p decay branch of this nucleus. The experimental search for 26 S was performed by fragmentation of a 50.3 A MeV 32 S beam. No events of a particle-stable 26 S or 25 P (a presumably proton-unstable subsystem of 26 S ) were observed. Based on the obtained production systematics, an upper half-life limit of T1/2<79 ns was established from the time-of-flight through the fragment separator. Together with the theoretical lifetime estimates for two-proton decay, this gives a decay energy limit of Q2p>640 keV for 26 S . Analogous limits for 25 P are found as T1/2 < 38 ns and Qp>110 keV . In the case that the one-proton emission is the main branch of the 26 S decay, a limit Q2p>230 keV would follow for this nucleus. According to these limits, it is likely that 26 S resides in the picosecond lifetime range.
THE PATH TO IMPROVED REACTION RATES FOR ASTROPHYSICS
Authors: RAUSCHER THOMAS
Published: March 2011

This review focuses on nuclear reactions in astrophysics and, more specifically, on reactions with light ions (nucleons and α particles) proceeding via the strong interaction. It is intended to present the basic definitions essential for studies in nuclear astrophysics, to point out the differences between nuclear reactions taking place in stars and in a terrestrial laboratory, and to illustrate some of the challenges to be faced in theoretical and experimental studies of those reactions. The discussion revolves around the relevant quantities for astrophysics, which are the astrophysical reaction rates. The sensitivity of the reaction rates to the uncertainties in the prediction of various nuclear properties is explored and some guidelines for experimentalists are also provided.
ANALYTICAL SOLUTIONS FOR VIBRATION OF SIMPLY SUPPORTED NONLOCAL NANOBEAMS WITH AN AXIAL FORCE
Authors: LI C. , LIM C. W. , YU J. L. , ZENG Q. C.
Published: March 2011

This paper presents exact, analytical solutions for the transverse vibration of simply supported nanobeams subjected to an initial axial force based on nonlocal elasticity theory. Classical continuum theory is inherently size independent while nonlocal elasticity exhibits size dependence. The latter has significant effects on bending moment, which results in a conceptually different definition of a new effective nonlocal bending moment with respect to the corresponding classical bending moment. A sixth-order partial differential governing equation is subsequently obtained. The effects of nonlocal nanoscale on the vibration frequencies and mode shapes are considered and analytical solutions are solved. Effects of the nonlocal nanoscale and dimensionless axial force including axial tension and axial compression on the first three mode frequencies are presented and discussed. It is found that the nonlocal nanoscale induces higher natural frequencies and stiffness of the nano structures.
DERIVATIONS ON MORITA RINGS AND GENERALIZED DERIVATIONS
Authors: AL-NOFAYEE S. , NAUMAN S. K.
Published: March 2011

In this note, derivations on Morita rings (generalized matrix rings) are introduced and generalized derivations on rings are proved to be Morita invariant without involvement of any homology theory.
ON A THEOREM OF HUPPERT
Authors: SHI JIANGTAO , ZHANG CUI
Published: March 2011

A well-known theorem of Huppert states that a finite group is soluble if its every proper subgroup is supersoluble. In this paper, we proved the following result: let G be a finite group. (1) If G has exactly n non-supersoluble proper subgroups, where 0 ≤ n ≤ 7 and n ≠ 5, then G is soluble. (2) G is a non-soluble group with exactly five non-supersoluble proper subgroups if and only if all non-supersoluble proper subgroups are conjugate maximal subgroups and G/Φ(G) ≅ A5, where Φ(G) is the Frattini subgroup of G. Furthermore, we also considered the influence of the number of non-abelian proper subgroups on the solubility of finite groups.