bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantifying hillslope erosion rates and processes for a coastal California landscape over varying timescales
Authors: O'Farrell Colin R. , Heimsath Arjun M. , Kaste James M. 
Published: September 2006

AbstractThe Earth's surface erodes by processes that occur over different spatial and temporal scales. Both continuous, low‐magnitude processes as well as infrequent, high‐magnitude events drive erosion of hilly soil‐mantled landscapes. To determine the potential variability of erosion rates we applied three independent, field‐based methods to a well‐studied catchment in the Marin Headlands of northern California. We present short‐term, basin‐wide erosion rates determined by measuring pond sediment volume (40 years) and measured activities of the fallout nuclides 137Cs and 210Pb (40–50 years) for comparison with long‐term (>10 ka) rates previously determined from in situ‐produced cosmogenic 10Be and 26Al analyses. In addition to determining basin‐averaged rates, 137Cs and 210Pb enable us to calculate point‐specific erosion rates and use these rates to infer dominant erosion processes across the landscape. When examined in the context of established geomorphic transport laws, the correlations between point rates of soil loss from 137Cs and 210Pb inventories and landscape morphometry (i.e. topographic curvature and upslope drainage area) demonstrate that slope‐driven processes dominate on convex areas while overland flow processes dominate in concave hollows and channels. We show a good agreement in erosion rates determined by three independent methods: equivalent denudation rates of 143 ± 41 m Ma−1 from pond sediment volume, 136 ± 36 m Ma−1 from the combination of 137Cs and 210Pb, and 102 ± 25 m Ma−1 from 10Be and 26Al. Such agreement suggests that erosion of this landscape is not dominated by extreme events; rather, the rates and processes observed today are indicative of those operating for at least the past 10 000 years. Copyright © 2006 John Wiley & Sons, Ltd.
The ‘natural’ endpoint of dementia: death from cachexia or dehydration following palliative care?
Authors: Koopmans Raymond T. C. M. , van der Sterren Karin J. M. A. , van der Steen Jenny T. 
Published: October 2006

AbstractObjectivesTo investigate the causes of death in nursing home patients with dementia, and to compare causes of death in patients who survive until the final phase of dementia with those who die before reaching that phase, adjusted for potential confounders.DesignObservational analysis of a cohort of patients with a prospective follow‐up.SettingPsychogeriatric nursing home ‘Joachim en Anna’ in Nijmegen, the Netherlands.ParticipantsEight hundred and ninety dementia patients admitted between 1980 and 1989. All patients were followed until death.MeasurementsThe final phase of dementia was defined as total impairment on 20 items of a functional status questionnaire. Immediate causes of death (part 1a of the Dutch death certificate) were classified by the International Classification of Health Problems in Primary Care.ResultsThe three most important reported immediate causes of death were cachexia/dehydration (35.2%), cardio‐vascular disorders (20.9%) and acute pulmonary diseases (20.1%), mainly pneumonia. Cachexia/dehydration was particularly common as a cause of death of patients who survived to the final phase (53.2%); survival to the final phase of dementia was an independent predictor of cachexia/dehydration as an immediate cause of death with reference to cardiovasculair disorders in multinomial regression adjusted for age at death, gender, and type of dementia.ConclusionPatients who survive to the final phase of dementia are more likely to die from cachexia or dehydration than those who die before. The findings contribute to a debate on what should be reported as the immediate cause of death in dementia including perspectives from a palliative care viewpoint. Copyright © 2006 John Wiley & Sons, Ltd.
Detecting and characterizing reactive metabolites by liquid chromatography/tandem mass spectrometry
Authors: Ma Shuguang , Subramanian Raju 
Published: September 2006

AbstractMetabolic activation of a drug leading to reactive metabolite(s) that can covalently modify proteins is considered an initial step that may lead to drug‐induced organ toxicities. Characterization of reactive metabolites is critical to designing new drug candidates with an improved toxicological profile. High performance liquid chromatography (HPLC) coupled with mass spectrometry (MS) predominates over all analytical tools used for screening and characterization of reactive metabolites. In this review, a brief description of experimental approaches employed for assessing reactive metabolites is followed by a discussion on the reactivity of acyl glucuronides and acyl coenzyme A thioesters. Techniques for high‐throughput screening and quantitation of reactive metabolite formation are also described, along with proteomic approaches used to identify protein targets and modification sites by reactive metabolites. Strategies for dealing with reactive metabolites are reviewed. In conclusion, we discuss the challenges and future needs in this field of research. Copyright © 2006 John Wiley & Sons, Ltd.
Micromechanical Testing of Individual Collagen Fibrils
Authors: van der Rijt Joost A. J. , van der Werf Kees O. , Bennink Martin L. , Dijkstra Pieter J. , Feijen Jan 
Published: September 2006

AbstractSummary: A novel method based on AFM was used to attach individual collagen fibrils between a glass surface and the AFM tip, to allow force spectroscopy studies of these. The fibrils were deposited on glass substrates that are partly coated with Teflon AF®. A modified AFM tip was used to accurately deposit epoxy glue droplets on either end of the collagen fibril that cross the glass‐Teflon AF® interface, as to such attach it with one end to the glass and the other end to the AFM tip. Single collagen fibrils have been mechanically tested in ambient conditions and were found to behave reversibly up to stresses of 90 MPa. Within this regime a Young's modulus of 2–7 GPa was obtained. In aqueous media, the collagen fibrils could be tested reversibly up to about 15 MPa, revealing Young's moduli ranging from 0.2 to at most 0.8 GPa.
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Polynomial stability of operator semigroups
Authors: Bátkai András , Engel Klaus‐Jochen , Prüss Jan , Schnaubelt Roland 
Published: September 2006

AbstractWe investigate polynomial decay of classical solutions of linear evolution equations. For bounded strongly continuous semigroups on a Banach space this property is closely related to polynomial growth estimates of the resolvent of the generator. For systems of commuting normal operators polynomial decay is characterized in terms of the location of the generator spectrum. The results are applied to systems of coupled wave‐type equations. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Transition of nuclear proteins and chromatin structure in spermiogenesis of Sepia officinalis
Authors: MartÍnez‐Soler F. , Kurtz K. , Ausió J. , Chiva M. 
Published: September 2006

AbstractDuring spermiogenesis of Sepia officinalis histones are directly substituted by a molecule of precursor protamine, which is later transformed into the protamine through a deletion of the amino terminal end. In the present work, it is shown that the pattern of spermiogenic chromatin condensation consists of a phase of “patterning” and a phase of “condensation.” In the phase of patterning, three structural remodelings are produced in the chromatin structure: [somatic‐like chromatin → 18 nm granules → 25 nm fibers → 44 nm fibers]. The first remodeling of the chromatin into granules of 18 nm takes place without the entrance of specific proteins in the spermiogenic nuclei. The second remodeling [granules of 18 nm → fibers of 25 nm] is due to the entrance of the precursor protamine and its interaction with the DNA–histone complex. The third remodeling [fibers of 25 nm → fibers of 44 nm] occurs simultaneously with the disappearance of histones from the chromatin. In the phase of condensation, the fibers of 44 nm coalesce among themselves to form progressively larger aggregates of chromatin. In this phase there are no substantial variations in the nuclear proteins, so that the condensation of the chromatin must respond to posttranscriptional changes of the precursor protamine (dephosphorylation, deletion of the amino‐terminal end). Mol. Reprod. Dev. © 2006 Wiley‐Liss, Inc.
Regulation of MMP‐9 expression and activity in the mouse uterus by estrogen
Authors: Zhang Xuan , Christenson Lane K. , Nothnick Warren B. 
Published: September 2006

AbstractMatrix metalloproteinases (MMPs) are spatiotemporally expressed in the uterus across normal estrous and menstrual cycles and are known to participate in the extensive endometrial tissue remodeling. MMP‐9/gelatinase B is one of the major MMPs found in the uterus that modulates uterine biology during various reproductive processes. Although it seems that uterine MMP‐9 is under ovarian steroid hormonal control, there are conflicting reports regarding steroidal hormonal regulation of MMP‐9 expression, and there is little information on the effects of estrogen in vivo in this respect. We therefore examined the steroidal regulation of MMP‐9 within the mouse uterus. Female mice (2–3 months old) were ovariectomized and treated with estradiol‐l7β (E2) or E2 + progesterone (P4) and uterine gelatinase activity and expression were determined. Gelatin zymography revealed that E2 alone or in combination with P4 increased MMP‐9 activation, whereas Northern analysis showed that E2 decreased MMP‐9 steady state mRNA expression and an estrogen receptor antagonist ICI‐182, 780 blocked this effect. In contrast, uterine MMP‐2 expression and activity were not affected by steroidal treatments. Pretreatment with a transcription inhibitor actinomycin D or translation inhibitor cycloheximide indicates that E2 regulates uterine MMP‐9 at multiple points, involving transcriptional and posttranscriptional control as well as modulation of inhibitor activities. Collectively, these data suggest that E2 regulates uterine MMP‐9 expression and activity in vivo via a complex mechanism. This estrogen regulation of MMP‐9 activity may play an important role in uterine tissue remodeling. Mol. Reprod. Dev. © 2006 Wiley‐Liss, Inc.
Characterization and differential expression of vascular endothelial growth factor isoforms and receptors in swine corpus luteum throughout estrous cycle
Authors: Ribeiro Luciana Andrea , Bacci Maria Laura , Seren Eraldo , Tamanini Carlo , Forni Monica 
Published: September 2006

AbstractCorpus luteum (CL) undergoes growth and regression during each estrous cycle; these processes are accompanied by growth and regression of the luteal vascular bed. Vascular endothelial growth factor (VEGF) is the main regulator of angiogenesis, inducing endothelial cell proliferation, migration, vascular permeability, and vessel lumen formation. VEGF presents several isoforms that are produced by alternative splicing of the same mRNA transcript. We determined by real time RT‐PCR the expression patterns of VEGF isoform and receptor mRNAs, as well as the VEGF protein levels in pig CL throughout a whole estrous cycle. Four novel VEGF isoforms (VEGF144, VEGF147, VEGF182, and VEGF164b) were found for the first time in swine and the seven identified isoforms can be grouped in four different patterns of expression. The most expressed splice variants were VEGF120 and VEGF164. All isoforms showed their highest mRNA levels in newly formed CLs (day 1), followed by a decrease during mid‐late luteal phase (days 10–17), except for VEGF182, VEGF188 and VEGF144 that showed a differential regulation during late luteal phase (day 14) or at luteolysis (day 17). VEGF protein levels paralleled the most expressed and secreted VEGF120 and VEGF164 isoforms. The VEGF receptors mRNAs showed a different pattern of expression in relation to their ligands, increasing between day 1 and 3 and gradually decreasing during the mid‐late luteal phase. The differential regulation of VEGF isoforms may suggest specific physiological roles for some of them, particularly in angioregression occurring during the apoptotic structural luteolysis. Mol. Reprod. Dev. © 2006 Wiley‐Liss, Inc.
Plectin defects in epidermolysis bullosa simplex with muscular dystrophy
Authors: McMillan J.R. , Akiyama M. , Rouan F. , Mellerio J.E. , Lane E.B. , Leigh I.M. , Owaribe K. , Wiche G. , Fujii N. , Uitto J. , Eady R.A.J. , Shimizu H. 
Published: September 2006

AbstractEpidermolysis bullosa simplex with muscular dystrophy (EBS‐MD, MIM 226670) is caused by plectin defects. We performed mutational analysis and immunohistochemistry using EBS‐MD (n = 3 cases) and control skeletal muscle to determine pathogenesis. Mutational analysis revealed a novel homozygous plectin‐exon32 rod domain mutation (R2465X). All plectin/HD1‐121 antibodies stained the control skeletal muscle membrane. However, plectin antibodies stained the cytoplasm of type II control muscle fibers (as confirmed by ATPase staining), whereas HD1‐121 stained the cytoplasm of type I fibers. EBS‐MD samples lacked membrane (n = 3) but retained cytoplasmic HD1‐121 (n = 1) and plectin staining in type II fibers (n = 3). Ultrastructurally, EBS‐MD demonstrated widening and vacuolization adjacent to the membrane and disorganization of Z‐lines (n = 2 of 3) compared to controls (n = 5). Control muscle immunogold labeling colocalized plectin and desmin to filamentous bridges between Z‐lines and the membrane that were disrupted in EBS‐MD muscle. We conclude that fiber‐specific plectin expression is associated with the desmin‐cytoskeleton, Z‐lines, and crucially myocyte membrane linkage, analogous to hemidesmosomes in skin. Muscle Nerve, 2006
Down‐regulation of torp4a, encoding the Drosophila homologue of torsinA, results in increased neuronal degeneration
Authors: Muraro Nara I. , Moffat Kevin G. 
Published: September 2006

AbstractEarly‐onset torsion dystonia is a dominant motor disorder linked to mutations in torsinA. TorsinA is weakly related to a superfamily of chaperone‐like proteins. The function of the torsin group remains largely unknown. Here we use RNAi and over‐expression to analyze the function of torp4a, the only Drosophila torsin. Targeted down‐regulation in the eye causes progressive degeneration of the retina. Conversely, over‐expression of torp4a protects from age‐related degeneration. In the retinas of young animals, a correlation with the lysosome‐related organelle, the pigment granule, is also observed. Lowering torp4a causes an increase in pigment granules, while over‐expression causes loss of granules. We have performed a screen for genetic interactors of torp4a identifying a number mutants, including two members of the AP‐3 complex. Other genetic interactors found included genes related to actin and myosin function. Our findings implicate the Drosophila torsin, torp4a, to function with molecules consistent with already predicted roles in the endoplasmic reticulum/nuclear envelope compartment, and have identified potential new interactions with AP‐3 like components. © 2006 Wiley Periodicals, Inc. J Neurobiol, 2006
Breeding status affects motoneuron number and muscle size in naked mole‐rats: Recruitment of perineal motoneurons?
Authors: Seney Marianne , Goldman Bruce D. , Forger Nancy G. 
Published: September 2006

AbstractNaked mole‐rats live in large colonies and exhibit a strict reproductive hierarchy. Each colony has one breeding female and one to three breeding males; all other individuals are nonreproductive subordinates. Subordinates show a remarkable lack of sex differences in behavior and anatomy, but can become reproductive if removed from the colony. We recently reported that the striated perineal muscles and their innervating motoneurons, which are sexually dimorphic in all other mammals examined to date, are not dimorphic in subordinate naked mole‐rats. Here we asked whether sexual differentiation of this neuromuscular system occurs when a subordinate becomes a breeder. The size and number of cells within Onuf's nucleus (homologue of the rat spinal nucleus of the bulbocavernosus) as well as perineal muscle volume were examined in subordinate and breeding naked mole‐rats of both sexes. Sex differences in perineal motoneurons were not observed, regardless of social status. To our surprise, however, counts of motoneurons in Onuf's nucleus were increased ∼30% in breeders of both sexes. This was accompanied by a reciprocal decrease in cells in Onuf's nucleus that were characterized by small soma size, and lacked a clear nucleus or nucleolus. Although not exhibiting typical motoneuron morphology, some of these small cells were positive for the motoneuron marker, SMI‐32. The neuronal changes correlate with increased perineal muscle volumes in breeders. We propose that small, relatively undifferentiated cells are recruited to the pool of large Onuf's nucleus motoneurons when subordinate naked mole‐rats become breeders. © 2006 Wiley Periodicals, Inc. J Neurobiol, 2006
Fabrication of high‐performance, gradient‐refractive‐index plastic rods with surfmer‐cluster‐stabilized nanoparticles
Authors: Liu Jui‐Hsiang , Yang Po‐Chih , Chiu Yi‐Hong 
Published: September 2006

AbstractA novel method was developed with surfmer‐cluster‐stabilized silver nanoparticles to prepare high‐performance, gradient‐refractive‐index (GRIN) plastic rods based on methyl methacrylate. To fabricate the GRIN plastic rods, a novel polymerizable surfactant (surfmer) of 4‐(11‐acryloxyundecyloxy)benzoic acid (AUBA) was synthesized. Silver nanoparticles were prepared with a reverse micelle method in the presence of the novel surfmer. During the fabrication of the silver nanoparticles, the sodium salt of AUBA was formed. GRIN plastic rods were fabricated through centrifugal polymerization and then were heat‐treated at 100 °C under 0.1 Torr for 24 h to remove residual monomers and water. The distribution of the surfmer‐cluster‐stabilized nanoparticles inside the plastic rods was studied with transmission electron microscopy (TEM). The real‐image transmission through the fabricated rods was also confirmed. The results obtained in this investigation suggested that the control of the distribution of surfmer‐cluster‐stabilized nanoparticles could be used to fabricate GRIN rods. Furthermore, the existence of the crosslink‐like surfmers increased the thermal stability of the plastic rods. The GRIN distribution of the rods was established by the dispersion of nanoparticles inside the plastic rods through TEM analysis, refractive‐index analysis, and real‐image transmission. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5933–5942, 2006
Cyclic insulin‐regulated aminopeptidase (IRAP)/AT4 receptor ligands
Authors: Axén Andreas , Lindeberg Gunnar , Demaegdt Heidi , Vauquelin Georges , Karlén Anders , Hallberg Mathias 
Published: September 2006

AbstractThe angiotensin IV receptor (AT4 receptor) is the insulin‐regulated aminopeptidase enzyme (IRAP, EC 3.4.11.3). This membrane‐spanning enzyme belongs to the M1 family of zinc‐dependent metallo‐peptidases. It has been proposed that AT4 receptor ligands exert their physiological effects by binding to the active site of IRAP and thereby inhibiting the catalytic activity of the enzyme. The biological activity of a large series of linear angiotensin IV analogs was previously disclosed. Herein, the synthesis and biological evaluation of a series of angiotensin IV analogs, encompassing macrocyclic ring systems of different sizes, are presented. It is demonstrated that disulfide cyclizations of angiotensin IV can deliver ligands with high IRAP/AT4 receptor affinity. One ligand, with an 11‐membered ring system (4), inhibited human IRAP and aminopeptidase N (AP‐N) activity with similar potency as angiotensin IV but was considerably more stable than angiotensin IV toward enzymatic degradation. The compound provides a promising starting point for further optimization toward more drug‐like derivatives. The cyclic constrained analogs allowed us to propose a tentative bioactive conformation of angiotensin IV and it seems that the peptide adopts an inverse γ‐turn at the C‐terminal. Copyright © 2006 European Peptide Society and John Wiley & Sons, Ltd.
FEM modelling of surface acoustic wave in diamond layered structure
Authors: Le Brizoual L. , Sarry F. , Moreira F. , Elmazria O. 
Published: September 2006

AbstractThis paper describes a general finite element method (FEM) for the AC steady state analysis of two‐dimensional piezoelectric devices. The method is applied to a diamond based surface acoustic wave (SAW) layered structure. We determined the penetration depth of the elastic waves corresponding to ZnO layer of 1 µm thick and spatial periodicity of 4 µm. The structure admittance response shows six peaks corresponding to the mode 0, 1 and 2. The penetration depth in diamond is around 8 µm except for the mode 2 where it reaches 12 µm. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
First‐principles characterization of amorphous carbon nitride systems: structural and electronic properties
Authors: Titantah J. T. , Lamoen D. 
Published: September 2006

AbstractA series of carbon nitride structures have been generated, by using a classical potential in a Metropolis Monte Carlo liquid quench procedure. The resulting structures are relaxed further using the density functional theory approach. Structures are generated for various mass densities and varying N/C ratio so that all possible C–N bonding configurations are produced. Structural analysis of the equilibrated structures are performed and the effect of nitrogen inclusion on the formation of curved carbon systems is evidenced. Density of states and energy‐loss near‐edge structure calculations show that nitrogen incorporation modifies the valence and conduction bands of amorphous carbon (a‐C). X‐ray photoelectron spectroscopy (XPS) calculations within the first‐principles methodology are also performed on the generated a‐C nitride systems. Depending on the carbon bonding configuration, the carbon 1s energies are found to vary from 283 eV to 288 eV while those of nitrogen are found to range from 397 eV to 402 eV. The experimentally observed N 1s XPS features of a‐C nitride systems are correlated with the nitrogen bonding state with carbon, the degree of delocalization of the nitrogen lone pair and the C–N bond length. In particular, our calculations support the interpretation of the N 1s feature at an energy of about 398.4 eV to two‐coordinated N atoms whose immediate neighbors enhance a delocalization of the N lone pair of electrons. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)