bluuebunny/crossref_metadata_2025 huggingface dataset:
The velocity of microtubule sliding: Its stability and load dependency
Authors: Ishijima Sumio
Published: August 2007

It is now well understood that ATP‐driven active sliding between the doublet microtubules in the sperm axoneme generates flagellar movement. However, much remains to be learned about how this movement is controlled. Detailed analyses of the flagellar beating of the mammalian spermatozoa revealed that there were two beating modes at a constant rate of microtubule sliding: that is, a nearly constant‐curvature beating in nonhyperactivated spermatozoa and a nearly constant‐frequency beating in hyperactivated spermatozoa. The constant rate of microtubule sliding suggests that the beat frequency and waveform of the flagellar beating are dependently regulated. Comparison of the sliding velocity of several mammalian and sea urchin sperm flagella with their mechanical property clarified that the sliding velocity of the microtubule was determined by the stiffness of the flagellum at its base, and that its relationship was expressed by a logarithmic equation that is similar to the classical force‐velocity equation of the muscle contraction. Data from sea urchin spermatozoa also satisfied the equation, suggesting that the same microtubule sliding system functions in both the mammalian and echinoderm spermatozoa. Cell Motil. Cytoskeleton 2007. © 2007 Wiley‐Liss, Inc.
Mammalian cilia function is independent of the polymeric state of tubulin glycylation
Authors: Dossou Starlette J. Y. , Bré Marie‐Hélène , Hallworth Richard
Published: August 2007

Polyglycylation is a polymeric post‐translational modification of tubulin that is ubiquitous and widely present in cilia and flagella. It consists of the addition of highly variable numbers of glycyl residues as side chains onto the γ carboxyl group of specific glutamyl residues at the C‐termini of α‐ and β‐tubulin. The function of polyglycylation is poorly understood, however, studies in Tetrahymena have shown that the mutation of polyglycylation sites in β‐tubulin resulted in axonemal abnormality or lethality. This suggests that polyglycylation is functionally essential in protists. We hypothesize that polyglycylation is also essential in mammalian cilia and that the extent of polyglycylation has functional significance. In this study, we examined polyglycylation states in ciliated tissues and in mouse tracheal epithelial cell cultures. We utilized two antibodies, TAP 952 and AXO 49, which recognize glutamyl sites possessing monomeric glycylation sites and glutamyl sites possessing polymeric glycylation sites, respectively. Monomeric glycylation sites were observed in cilia of all the ciliated tissues examined but were invariably excluded from the distal tips. In contrast, polymeric glycylation sites were rare, but when observed, they were localized at the bases of cilia. During ciliogenesis, in epithelial cell cultures, monomeric glycylation sites were observed, but the extent of polymeric glycylation sites were variable and were only observed during the early stages of the cultures. Our observations suggest that while monomeric glycylation sites are universal and likely essential in mammalian cilia, polymeric glycylation sites are not required for ciliary beating. Rather, our observations suggest that the number of added glycyl residues increases progressively from the tips of cilia toward their bases. Cell Motil. Cytoskeleton 2007. © 2007 Wiley‐Liss, Inc.
BRAFV600E mutation and p27kip1 expression in papillary carcinomas of the thyroid ≤1 cm and their paired lymph node metastases
Authors: Rodolico Vito , Cabibi Daniela , Pizzolanti Giuseppe , Richiusa Pierina , Gebbia Nicola , Martorana Anna , Russo Antonio , Amato Marco C. , Galluzzo Aldo , Giordano Carla
Published: August 2007

BACKGROUND.

BRAFV600E mutation and p27kip1 expression have been introduced as novel indicators that may predict prognosis in different tumors, as well as in papillary thyroid carcinomas.

METHODS.

Tissue samples from 214 consecutive patients who underwent total or near‐total thyroidectomy with histological diagnosis of papillary thyroid carcinoma (PTC) ≤1 cm were analyzed for BRAFV600E mutation by a real‐time, allele‐specific amplification and for p27kip1 expression by immunohistochemistry.

RESULTS.

The BRAFV600E mutation was detected in 88 of the tumors examined, with significant differences between groups with and without lymph node (LN) metastases; the mean age of patients with BRAFV600E mutation was significantly higher than that of patients without mutations. A significant association was found between low p27Kip1 protein expression and multifocality, bilaterality, and extrathyroidal extension, in addition to LN metastasis. In 42 cases with LN metastases, 23 harbored the BRAFV600E mutation in the metastatic tumor and presented a wider diameter of the largest metastatic area, a higher number of involved LNs, and a higher percentage of metastatic lesions with extracapsular extension of LN (ECE‐LN). A significantly lower mean value of p27Kip1 was observed in LNs harboring the BRAFV600E mutation and in ECE‐LN; an inverse correlation was found between p27Kip1 and the number of metastatic LNs, as well as the diameter of the largest metastatic area in LN.

CONCLUSIONS.

The authors' data suggested that BRAFV600E mutation and p27Kip1 down‐regulation in cancer cells of PTC ≤1 cm may be factors that facilitate tumor‐cell growth and progression once these are seeded in the LNs. Cancer 2007. © 2007 American Cancer Society.
Management of prostate cancer recurrences after radiation therapy‐brachytherapy as a salvage option
Authors: Allen Gregory W. , Howard Andrew R. , Jarrard David F , Ritter Mark A.
Published: August 2007

Depending on initial prognostic factors, an estimated 10%–60% of men who undergo definitive radiation therapy for prostate cancer may experience a biochemical recurrence. Even though hormonal therapy is standard for metastatic recurrences, no consensus exists on optimal salvage therapy for those recurrences thought confined to the prostate. Salvage treatment options for these local recurrences have historically been limited to salvage prostatectomy, hormonal therapy, or cryotherapy. Salvage prostate brachytherapy, however, uses a widely available technique and may provide another option for attaining disease control in patients with localized failures, although only about 110 cases have been reported in the literature. In this report, the authors have described their own series of salvage brachytherapy cases as well as presented a review of other such series reported in the literature. In addition, the authors included a comprehensive review of published experiences with surgery and cryotherapy as salvage options. It appears that salvage brachytherapy, when combined with careful patient selection, is at least as effective as other salvage options with comparable or potentially fewer treatment‐related side effects. Cancer 2007. © 2007 American Cancer Society.
Changes in cognitive functioning in the year after hematopoietic stem cell transplantation
Authors: Jacobs Sheri R. , Small Brent J. , Booth‐Jones Margaret , Jacobsen Paul B. , Fields Karen K.
Published: August 2007

BACKGROUND.

The current study examined changes in multiple domains of cognitive functioning of hematopoietic stem cell transplantation (HSCT) candidates tested pretransplantation, 6 months posttransplantion, and 12 months posttransplantion.

METHODS.

Using a sequential longitudinal design, 476 patients were randomized to be tested at all 3 timepoints, at 6 and 12 months posttransplantion, or at only 12 months posttransplantion. Participants completed a comprehensive battery of neuropsychologic tests that indexed memory, psychomotor speed, attention, and executive functioning, and provided a total neuropsychologic performance score (TNP).

RESULTS.

The results indicate that performance on cognitive abilities, except for attention, significantly improved across the 1‐year follow‐up period after HSCT. Performance on the TNP and all cognitive domains was superior or equal to population normative values by the 12‐month measurement point. The results also indicate that repeated exposure to tests led to better performance on motor speed and the TNP and that attrition influenced the TNP, such that those who remained in the longitudinal sample exhibited greater longitudinal improvement in scores as compared with patients who left the sample.

CONCLUSIONS.

The findings of the current study suggest that although patients undergoing HSCT experience cognitive deficits during the period just before transplantion, cognitive functioning returns to normative values within a year after transplantion. Cancer 2007. © 2007 American Cancer Society.
Automatic capture and efficient storage of e‐Science experiment provenance
Authors: Barga Roger S. , Digiampietri Luciano A.
Published: August 2007

For the first provenance challenge, we introduce a layered model to represent workflow provenance that allows navigation from an abstract model of the experiment to instance data collected during a specific experiment run. We outline modest extensions to a commercial workflow engine so it will automatically capture provenance at workflow runtime. We also present an approach to store this provenance data in a relational database. Finally, we demonstrate how core provenance queries in the challenge can be expressed in SQL and discuss the merits of our layered representation. Copyright © 2007 John Wiley & Sons, Ltd.
Hypophosphorylated TCR/CD3ζ signals through a Grb2‐SOS1‐Ras pathway in Lck knockdown cells
Authors: Methi Trond , Ngai Jacob , Vang Torkel , Torgersen Knut M. , Taskén Kjetil
Published: August 2007

Despite the loss of proximal TCR‐dependent signaling events, downstream T cell responses are paradoxically augmented in T cells with siRNA‐mediated Lck knockdown (Methi et al., J. Immunol. 2005. 175: 7398–7406). This indicates that alternative Lck‐independent pathways of T cell activation exist or that low levels of Lck elicit other signals than normal T cell activation. Here we report the recruitment of Grb2‐SOS1 to CD3ζ of the TCR complex after prolonged anti‐CD3 (OKT3) stimulation in T cells with Lck knockdown. Grb2 bound to incompletely phosphorylated ITAM1 with the pY‐Y configuration in a solid‐phase assay, but was excluded by ZAP‐70 in the doubly phosphorylated pY‐pY conformation. Ras and ERK1/2 activation was augmented after prolonged stimulation in T cells with Lck knockdown compared to control, leading to increased activation of the proximal IL‐2 promoter (NFAT‐AP‐1). Finally, the phosphorylation of Ras‐GAP was strongly suppressed in Lck knockdown cells, indicating that a Ras negative feedback mechanism is dependent on Lck.
γc cytokines provide multiple homeostatic signals to naive CD4+ T cells
Authors: Masse Guillemette X. , Corcuff Erwan , Decaluwe Hélène , Bommhardt Ursula , Lantz Olivier , Buer Jan , Di Santo James P.
Published: August 2007

Cytokines signaling through receptors sharing the common γ chain (γc), including IL‐2, IL‐4, IL‐7, IL‐9, IL‐15 and IL‐21, are critical for the generation and peripheral homeostasis of B, T and NK cells. To identify unique or redundant roles for γc cytokines in naive CD4+ T cells, we compared monoclonal populations of CD4+ T cells from TCR‐Tg mice that were γ, γ, CD127–/– or CD122–/–. We found that γ naive CD4+ T cells failed to accumulate in the peripheral lymphoid organs and the few remaining cells were characterized by small size, decreased expression of MHC class I and enhanced apoptosis. By over‐expressing human Bcl‐2, peripheral naive CD4+ T cells that lack γc could be rescued. Bcl‐2+ γ CD4+ T cells demonstrated enhanced survival characteristics in vivo and in vitro, and could proliferate normally in vitro in response to antigen. Nevertheless, Bcl‐2+ γ CD4+ T cells remained small in size, and this phenotype was not corrected by enforced expression of an activated protein kinase B. We conclude that γc cytokines (primarily but not exclusively IL‐7) provide Bcl‐2‐dependent as well as Bcl‐2‐independent signals to maintain the phenotype and homeostasis of the peripheral naive CD4+ T cell pool.

See accompanying commentary: http://dx.doi.org/10.1002/eji.200737721
PD‐L2 expression extends beyond dendritic cells/macrophages to B1 cells enriched for VH11/VH12 and phosphatidylcholine binding
Authors: Zhong Xuemei , Tumang Joseph R. , Gao Wenda , Bai Chunyan , Rothstein Thomas L.
Published: August 2007

B1 B cells are the major source of natural antibody that is essential for innate immunity. The B1 repertoire is skewed toward production of phosphatidylcholine (PtC)‐binding VH11 and VH12 immunoglobulin that plays a key role in immune defense against bacterial infection. Programmed death‐ligand 2 (PD‐L2) is a ligand for the immunosuppressive receptor programmed death‐1 (PD‐1). It has been reported that expression of PD‐L2 is restricted to dendritic cells and macrophages in mice. Here we show that 50–70% of resting peritoneal B1 cells express PD‐L2, which is not present or inducible on conventional B2 B cells or PD‐L2– B1 cells. Although PD‐L2+ and PD‐L2– B1 cells are similar in proliferative responses and spontaneous immunoglobulin secretion, PD‐L2+ B1 cells are highly enriched for expression of VH11 and VH12 genes and encompass the bulk of PtC‐binding B1 cells. These findings extend the range of known PD‐L2 expression to B cells and show that B1 cells identified by this marker express a specific repertoire associated with anti‐bacterial immunity.
Nickel Complexes with N2O Donor Ligands: Syntheses, Structures, Catalysis and Magnetic Studies
Authors: Chakraborty Jishnunil , Nandi Mahasweta , Mayer‐Figge Heike , Sheldrick William S. , Sorace Lorenzo , Bhaumik Asim , Banerjee Pradyot
Published: August 2007

Two new terephthalato‐bridged tetranuclear polymeric NiII complexes, namely [Ni4L41(μ‐tp‐κ4‐O)(H2O)2(μ‐tp‐κ2‐O)]·2C2H5OH·CH3OH·3H2O (1) and [Ni4L42(μ‐tp‐κ4‐O)(H2O)2(μ‐tp‐κ2‐O)]·3H2O (2) [L1 = N‐(3‐aminopropyl)‐5‐bromosalicylaldimine and L2 = N‐(3‐aminopropyl)salicylaldimine], are reported along with the syntheses and structures of the dicyanoargentate‐bridged polymeric complexes [Ni(L1)(H2O){Ag(CN)2}]α (3) and [Ni(L3)(MeOH){Ag(CN)2}]α (4) [L3 = N‐(3‐amino‐2,2‐dimethylpropyl)‐5‐bromosalicylaldimine]. All four complexes are found to be effective heterogeneous catalysts for the epoxidation of alkenes such as styrene, α‐methylstyrene and cyclohexene in the presence of tert‐butyl hydroperoxide. The variable‐temperature magnetic susceptibility measurements (300–2 K) of complex 1 show a fair degree of antiferromagnetic coupling between the NiII centers.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Facile Synthesis of Flexible Bis(pyrazol‐1‐yl)alkane and Related Ligands in a Superbasic Medium
Authors: Potapov Andrei S. , Domina Galina A. , Khlebnikov Andrei I. , Ogorodnikov Vladimir D.
Published: August 2007

Flexible ligands 1,3‐bis(pyrazol‐1‐yl)propanes, bis[2‐(pyrazol‐1‐yl)ethyl] ethers, and bis[2‐(3,5‐dimethylpyrazol‐1‐yl)ethyl]amine were prepared by a facile procedure involving the reaction of pyrazoles with 1,3‐dibromopropane, bis(2‐chloroethyl) ether or bis(2‐chloroethyl)amine hydrochloride in a superbasic medium (dimethyl sulfoxide/potassium hydroxide). Reaction of bis(2‐chloroethyl)amine and pyrazole unexpectedly led to 1,4‐bis[2‐(pyrazol‐1‐yl)ethyl]piperazine. The corresponding 4,4′‐diiodo‐substituted bis(pyrazole) derivatives were prepared by oxidative iodination with I2/HIO3/H2SO4 in acetic acid. Vilsmeier–Haak formylation of some of the prepared compounds yielded the corresponding dialdehydes.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Basic Ionic Liquids: Facile Solvents for Carbon–Carbon Bond Formation Reactions and Ready Access to Palladium Nanoparticles
Authors: Ye Chengfeng , Xiao Ji‐Chang , Twamley Brendan , LaLonde Aaron D. , Grant Norton M. , Shreeve Jean'ne M.
Published: August 2007

A basic ionic liquid was selected to serve as both the solvent and base for Heck, “copper‐free” Sonogashira reactions, and for homocoupling reactions of terminal alkynes. The ionic liquids with tertiary aliphatic amines are effective solvents for these reactions. Under reflux conditions, eight equivalent basic ionic liquids and Pd(OAc)2 in THF or acetone produced palladium colloids with diameters of (2.6 ± 0.3) or (3.7 ± 0.5) nm, respectively. Preliminary results for Knoevenagel condensations are also reported.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Cytogenetic effects of commercial formulations of deltamethrin and/or isoproturon on human peripheral lymphocytes and mouse bone marrow cells
Authors: Chauhan Lalit K.S. , Kumar Munish , Paul Bhola N. , Goel Sudhir K. , Gupta Shrawan K.
Published: August 2007

The cytogenetic effects of deltamethrin (DEL) and/or isoproturon (ISO) were examined in human lymphocytes and mouse bone marrow cells. Peripheral lymphocytes were exposed to DEL (2.5, 5, 10, or 20 μM), ISO (25, 50, 100, or 200μM), or DEL + ISO (2.5 + 25, 5 + 50, 10 + 100, or 20 + 200 μM) and cytogenic effects were evaluated via chromosomal aberrations (CA) and the cytokinesis‐block micronucleus assay (CBMN). Mice were orally gavaged to single dose of DEL (6.6 mg/kg), ISO (670 mg/kg), or DEL+ISO (6.6 + 670 mg/kg) for 24 hr or to DEL (3.3 mg/kg/day), ISO (330 mg/kg/day), or DEL + ISO (3.3 + 330 mg/kg/day) for 30 days and analyzed for CA. DEL induced a significant frequency of CA at 10 μM whereas ISO (25–100μM) alone, or in combination with DEL, did not show any significant effect. Micronucleus (MN) induction was observed to be concentration‐dependent though significant frequencies were observed at 5 μM DEL, 100 μM ISO, or 5 + 50 μM DEL + ISO. In mice, DEL inhibited the mitotic index (MI) significantly (P < 0.001) at 24 hr while ISO alone, or in combination with DEL, did not cause any statistically significant effect. Following a 24 hr exposure, DEL and ISO alone induced significant (P < 0.01) frequencies of CA, whereas DEL + ISO in combination did not. Furthermore, 30 days exposure of ISO significantly inhibited the MI (P < 0.02 or < 0.01) and induced CA while DEL alone, or in combination with ISO, resulted in no significant effect on CA or the MI. The present findings indicate that the in vitro and in vivo exposure of a commercial formulation of DEL can cause genotoxic effects in mammals. However, the coexposure of DEL and ISO did not show additive effects, but instead demonstrated somewhat reduced genotoxicity. Environ. Mol. Mutagen., 2007. © 2007 Wiley‐Liss, Inc.
Dynamics of soil erosion rates and controlling factors in the Northern Ethiopian Highlands – towards a sediment budget
Authors: Nyssen Jan , Poesen Jean , Moeyersons Jan , Haile Mitiku , Deckers Jozef
Published: August 2007

This paper analyses the factors that control rates and extent of soil erosion processes in the 199 ha May Zegzeg catchment near Hagere Selam in the Tigray Highlands (Northern Ethiopia). This catchment, characterized by high elevations (2100–2650 m a.s.l.) and a subhorizontal structural relief, is typical for the Northern Ethiopian Highlands. Soil loss rates due to various erosion processes, as well as sediment yield rates and rates of sediment deposition within the catchment (essentially induced by recent soil conservation activities), were measured using a range of geomorphological methods. The area‐weighted average rate of soil erosion by water in the catchment, measured over four years (1998–2001), is 14·8 t ha−1 y−1, which accounts for 98% of the change in potential energy of the landscape. Considering these soil loss rates by water, 28% is due to gully erosion. Other geomorphic processes, such as tillage erosion and rock fragment displacement by gravity and livestock trampling, are also important, either within certain land units, or for their impact on agricultural productivity. Estimated mean sediment deposition rate within the catchment equals 9·2 t ha−1 y−1. Calculated sediment yield (5·6 t ha−1 y−1) is similar to sediment yield measured in nearby catchments. Seventy‐four percent of total soil loss by sheet and rill erosion is trapped in exclosures and behind stone bunds. The anthropogenic factor is dominant in controlling present‐day erosion processes in the Northern Ethiopian Highlands. Human activities have led to an overall increase in erosion process intensities, but, through targeted interventions, rural society is now well on the way to control and reverse the degradation processes, as can be demonstrated through the sediment budget. Copyright © 2007 John Wiley & Sons, Ltd.
Investigating parabolic and nebkha dune formation using a cellular automaton modelling approach
Authors: Nield Joanna M. , Baas Andreas C. W.
Published: August 2007

Vegetation plays an important role in shaping the morphology of aeolian dune landscapes in coastal and semi‐arid environments, where ecogeomorphic interactions are complex and not well quantified. We present a Discrete ECogeomorphic Aeolian Landscape model (DECAL) capable of simulating realistic looking vegetated dune forms, permitting exploration of relationships between ecological and morphological processes at different temporal and spatial scales. The cellular automaton algorithm applies three simple rules that lead to self‐organization of complex dune environments, including nebkhas with distinctive deposition tails that form in association with mesquite‐type shrubs, and hairpin (long‐walled) parabolic dunes with trailing ridges that evolve from blowouts in association with vegetation succession. Changing the conditions of simulations produces differing landscapes that conform qualitatively to observations of real‐world dunes. The model mimics the response of the morphology to changes in sediment supply, vegetation distribution, density and growth characteristics, as well as initial disturbances. The introduction of vegetation into the model links spatial and temporal scales, previously dimensionless in bare‐sand cellular automata. Grid resolutions coarser than the representative size of the modelled vegetation elements yield similar morphologies, but when cell size is reduced to much smaller dimensions, the resultant landscape evolution is dramatically different. The model furthermore demonstrates that the relative response characteristics of the multiple vegetation types and their mutual feedback with geomorphological processes impart a significant influence on landscape equilibria, suggesting that vegetation induces a characteristic length scale in aeolian environments. This simple vegetated dune model illustrates the power and versatility of a cellular automaton approach for exploring the effects of interactions between ecology and geomorphology in complex earth surface systems. Copyright © 2007 John Wiley & Sons, Ltd.
Secotioid Agaricales (Basidiomycetes) from Mongolia
Authors: Dörfelt H. , Gube M.
Published: August 2007

A recapitulation of all findings of Mongolian secotioid Agaricales is given. Four species are known: Montagnea arenaria, Montagnea haussknechtii, Endoptychum agaricoides and Gyrophragmium dunalii. Two out of them, M. haussknechtii and E. agaricoides, are reported for the first time in Mongolia. An overview of distribution and systematic relationships of the taxa is given. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Beiträge zur Pilzflora von Mecklenburg‐Vorpommern (Deutschland), 6. Folge
Authors: Kreisel H.
Published: August 2007

Aus der Region Mecklenburg‐Vorpommern (Nordostdeutschland) werden Funde von 89 Arten Macromyceten und phytoparasitischen Pilzen mitgeteilt. Einige Taxa werden erstmals für die Region nachgewiesen, einige andere nach Jahrzehnten wiedergefunden. Die Verbreitung von neun dieser Arten wird auf Rasterkarten dargestellt. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
E‐cadherin abnormalities resulting from CPG methylation promoter in metastatic and nonmetastatic oral cancer
Authors: de Moraes Renato Vieira , Oliveira Denise Tostes , Landman Gilles , de Carvalho Fabrício , Caballero Otávia , Nonogaki Suely , Nishimoto Inês , Kowalski Luis Paulo
Published: August 2007

Background.

This study aims to compare the alterations in the methylation profiles of E‐cadherin in oral cancer, especially in tumors with lowest metatastic potential.

Methods.

Nine oral verrucous carcinomas (VCs), 20 oral well‐differentiated squamous cell carcinomas without lymph node involvement (SCC‐pN0), and 17 with lymph node involvement (SCC‐pN+) were analyzed using methylation‐specific polymerase chain reaction and immunohistochemical expression of E‐cadherin gene.

Results.

The immunohistochemical expression of E‐cadherin in VC was significantly higher (p = .016) when compared with SCC‐pN0 and SCC‐pN+ groups. The E‐cadherin gene methylation was not correlated with its abnormal immunohistochemical expression in VC and SCC‐pN0. All tumors of the SCC‐pN+ group with unmethylated E‐cadherin gene showed significant loss of E‐cadherin immunoexpression (p = .044).

Conclusions.

The E‐cadherin gene methylation presence in tumors with lowest invasive and metastatic potential, such as VC, suggests the early involvement of this epigenetic event in the multistep progression of the oral carcinogenesis. © 2007 Wiley Periodicals, Inc. Head Neck, 2008
Space–time rainfall variability in the Paute basin, Ecuadorian Andes
Authors: Celleri Rolando , Willems Patrick , Buytaert Wouter , Feyen Jan
Published: August 2007

Despite the importance of mountain ranges as water providers, knowledge of their climate variability is still limited, mostly due to a combination of data scarcity and heterogeneous orography. The tropical Andes share many of the main features of mountain ranges in general, and are subject to several climatic influences that have an effect on rainfall variability. Although studies have addressed the large‐scale variation, the basin scale has received little attention. Thus, the purpose of this study was to obtain a better understanding of rainfall variability in the tropical Andes at the basin scal, utilizing the Paute River basin of southern Ecuador as a case study. Analysis of 23 rainfall stations revealed a high spatial variability in terms of: (i) large variations of mean annual precipitation in the range 660–3400 mm; (ii) the presence of a non‐monotonic relation between annual precipitation and elevation; and (iii) the existence of four, sometimes contrasting, rainfall regimes. Data from seven stations for the period 1964–1998 was used to study seasonality and trends in annual, seasonal and monthly precipitation. Seasonality is less pronounced at higher elevations, confirming that in the páramo region, the main water source for Andean basins, rainfall is well distributed year round. Additionally, during the period of record, no station has experienced extreme concentrations of annual rainfall during the wet season, which supports the concept of mountains as reliable water providers. Although no regional or basin‐wide trends are found for annual precipitation, positive (negative) trends during the wet (dry) season found at four stations raises the likelihood of both water shortages and the risk of precipitation‐triggered disasters. The study demonstrates how variable the precipitation patterns of the Andean mountain range are, and illustrates the need for improved monitoring. Copyright © 2007 John Wiley & Sons, Ltd.
Stream network modelling using lidar and photogrammetric digital elevation models: a comparison and field verification
Authors: Murphy Paul N. C. , Ogilvie Jae , Meng Fan‐Rui , Arp Paul
Published: August 2007

A conventional, photogrammetrically derived digital elevation model (DEM; 10 m resolution) and a light detection and ranging (lidar)‐derived DEM (1 m resolution) were used to model the stream network of a 193 ha watershed in the Swan Hills of Alberta, Canada. Stream networks, modelled using both hydrologically corrected and uncorrected versions of the DEMs and derived from aerial photographs, were compared. The actual network, mapped in the field, was used as verification. The lidar DEM‐derived network was the most accurate representation of the field‐mapped network, being more accurate even than the photo‐derived network. This was likely due to the greater initial point density, accuracy and resolution of the lidar DEM compared with the conventional DEM. Lidar DEMs have great potential for application in land‐use planning and management and hydrologic modelling. The network derived from the hydrologically corrected conventional DEM was more accurate than that derived from the uncorrected one, but this was not the case with the lidar DEM. Copyright © 2007 John Wiley & Sons, Ltd.
Effects of postnatal ethanol exposure on neurotrophic factors and signal transduction pathways in rat brain
Authors: Fattori Vittorio , Abe Shin‐ichi , Kobayashi Kumiko , Costa Lucio G. , Tsuji Ryozo
Published: August 2007

Exposure to ethanol during development induces severe brain damage, resulting in a number of CNS dysfunctions including microencephaly and mental retardation. Potential targets of ethanol‐induced neurotoxicity include neurotrophic factors and their signal transduction pathways. In the present study, rat pups were given ethanol at the dose of 5 g kg−1 via gavage from postnatal day (PND) 5 to 8, and mRNA expression of nerve growth‐factor (NGF), brain‐derived neurotrophic factor (BDNF), and neurotrophic factor‐3 (NT‐3) in the cerebral cortex was examined, with attention to signal transduction, on PND 8. The mRNA level of BDNF was decreased by ethanol while those of NGF or NT‐3 were not changed. Brain weights were decreased and the levels of phospho‐MAPK, phospho‐p70S6K and phospho Akt were decreased while phosphor‐PKCζ and phospho‐CREB remained unchanged. These results suggest that BDNF and its related signal pathways involving Akt, MAPK and p70S6K are potential targets of ethanol‐induced developmental neurotoxicity. Copyright © 2007 John Wiley & Sons, Ltd.
Fiber density of electrospun gelatin scaffolds regulates morphogenesis of dermal–epidermal skin substitutes
Authors: Powell H. M. , Boyce S. T.
Published: August 2007

Porous, nowoven fibrous gelatin scaffolds were prepared using electrospinning. Electrospun scaffolds with varying fiber diameter, interfiber distance, and porosity were fabricated by altering the concentration of the electrospinning solution. Solution concentration was a significant predictor of fiber diameter, interfiber distance, and porosity with higher solution concentration correlated with larger fiber diameters and interfiber distances. The potential of electrospun gelatin as a scaffolding material for dermal and epidermal tissue regeneration was also evaluated. Interfiber distances >5.5 μm allowed deeper penetration of human dermal fibroblasts into the scaffold, whereas cells in scaffolds with more densely packed fibers were able to infiltrate only into the upper regions. Scaffolds with interfiber distances ≤10 μm exhibited well‐stratified dermal and epidermal layers including a continuous basal keratinocyte layer. These scaffolds were shown to form a keratinized layer like in normal skin, which acts as a barrier to infection and fluid loss. Interfiber distances between 5 and 10 μm appear to yield the most favorable skin substitute in vitro, demonstrating high cell viability, optimal cell organization, and excellent barrier formation. These results demonstrate the feasibility of electrospun gelatin as a scaffold for dermal–epidermal composite skin substitutes. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Bioglass®‐derived glass–ceramic scaffolds: Study of cell proliferation and scaffold degradation in vitro
Authors: Chen Q. Z. , Efthymiou A. , Salih V. , Boccaccini A. R.
Published: August 2007

Cell support function as well as cell proliferation on highly porous Bioglass®‐derived glass–ceramic scaffolds (designed for bone tissue engineering) have been assessed in vitro using osteoblast‐like cells (MG 63) cultured for up to 6 days. The biodegradation and mechanical stability of the scaffolds in the cell‐culture medium have also been investigated. It was found that the scaffolds had excellent cell supporting ability, with cells effectively infiltrating into and surviving at the center of the scaffolds. A quantitative study using the AlamarBlue™ assay revealed that the proliferation of cells on the glass–ceramic materials was comparable to that on the noncrystallized Bioglass®. While the crystalline phase in the glass–ceramic scaffolds transformed into a biodegradable amorphous calcium phosphate phase during cell culture, the mechanical strength of the scaffolds was maintained when compared with that of scaffolds incubated in simulated body fluid or immersed in cell‐free culture medium. It is believed that the attached cells and collagen secreted by cells could fill the micropores and microcracks on the surface of the foam struts, thus contributing to the mechanical stability of the degrading scaffolds. In summary, the developed glass–ceramic scaffolds possess the most essential features of a scaffold for bone tissue engineering: they are capable to support and foster relevant cells, able to provide temporary mechanical function, and biodegradable. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Mechanical, tribological, and biocompatibility properties of ZrN‐Ag nanocomposite films
Authors: Kertzman Z. , Marchal J. , Suarez M. , Staia M.H. , Filip P. , Kohli P. , Aouadi S.M.
Published: August 2007

Nanocomposite films of ZrN‐Ag were produced by reactive unbalanced magnetron sputtering, and their structural, chemical, mechanical, tribological, haemocompatibility, and antibacterial properties were studied as a function of film composition. The films formed a dense and homogeneous microstructure whereby nanocrystals of Ag are distributed evenly throughout the ZrN matrix. For small additions of silver, the hardness was found to increase, whereas the elastic modulus was found to decrease drastically. In the process of optimizing the deposition conditions, three kinds of coatings were prepared on 316 L surgical steel and tested by accelerated electrochemical polarization tests in order to detect the influence of Ag and the value of the bias potential on the corrosion performance of the system. Films produced under the optimum deposition conditions were, subsequently, deposited on medical grade Ti‐Al‐V and worn against ball‐bearing steel using a ball‐on‐disk tribotester in bovine serum and were found to have superior tribological properties compared with single‐phase ZrN coatings. The haemocompatibility of the films was assessed by investigating the adsorption of human serum albumin and fibrinogen on samples with different phase compositions. Quantification of the protein adsorption was carried out using spectroscopic ellipsometry, which confirmed the haemocompatibility of the films. Antibiotic activity of the films was quantified by incubating the films in bacterial cultures, namely, Staphylococcus epidermis, Staphylococcus aureus, and Escherichia coli. Films with a silver content > 10% exhibited superior antibacterial activity compared with the uncoated samples. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Effects of topographical surface modifications of electron beam melted Ti‐6Al‐4V titanium on human fetal osteoblasts
Authors: Ponader Sabine , Vairaktaris Eleftherios , Heinl Peter , Wilmowsky Cornelius v. , Rottmair Andreas , Körner Carolin , Singer Robert F. , Holst Stefan , Schlegel Karl A. , Neukam Friedrich W. , Nkenke Emeka
Published: August 2007

The aim of the study was to assess the suitability of different Ti‐6Al‐4V surfaces produced by the electron beam melting (EBM) process as matrices for attachment, proliferation, and differentiation of human fetal osteoblasts (hFOB 1.19). Human osteoblasts were cultured in vitro on smooth and rough‐textured Ti‐6Al‐4V alloy disks. By means of cell number and vitality and SEM micrographs cell attachment and proliferation were observed. The differentiation rate was examined by using quantitative real‐time PCR analysis for the gene expression of alkaline phosphatase (ALP), type I collagen (Coll‐I), bone sialoprotein (BSP) and osteocalcin (OC). After 3 days of incubation there was a significant higher vitality (p < 0.02) and proliferation (p < 0.02) of hFOB cells on smooth surfaces (Ra = 0.077 μm) and compact surfaces with adherent partly molten titanium particles on the surface (Ra ≤ 24.9 μm). On these samples cells spread over almost the whole surface. On porous surfaces with higher Ra values, cell proliferation was reduced significantly. Quantitative real‐time PCR analysis showed that the expression of osteogenic differentiation markers was not influenced by surface characteristics. Gene expression did not differ more than twofold for the different samples. Compact titanium samples with adherent partly molten titanium particles on the surface (Ra ≤ 24.9 μm) fabricated by the EBM process turned out to be best suited for cell proliferation, while highly rough surfaces (Ra ≥ 56.9 μm) reduced proliferation of hFOB cells. Surface characteristics of titanium can easily be changed by EBM in order to further improve proliferation. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Sp3‐Mediated VEGF regulation is dependent on phosphorylation by extra‐cellular signals regulated kinases (Erk)
Authors: Pagès Gilles
Published: August 2007

We have previously demonstrated that phosphorylation by Erk of Sp1 was essential for its full activity in the context of the VEGF promoter. Here, we show that Sp3, which, as Sp1, belongs to the GC‐rich binding transcription factor family, is also phosphorylated by Erk in vitro on serine 73. We have established cell lines in which expression of wild‐type Sp3 or a serine 73 to alanine (S73A) mutant is controlled by tetracycline. One of these cells lines also express the Raf:ER chimera which permits stimulation of Erk by tamoxifen. Difference in electrophoretic mobility and antibody directed against the phosphorylated serine 73 demonstrate that it is phosphorylated in vivo. Wild‐type Sp3 half‐life is increased upon Erk activation but the S73 is poorly implicated in this mechanism suggesting that Erk‐dependent Sp3 stability depends on other(s) domain(s) of the protein. Electro‐mobility shift assays and utilization of Gal4/Sp3 chimeric proteins show that Erk does not alter Sp3 DNA binding capacity but enhances its transcriptional activity. The S73A mutant Sp3 posses a reduced activity in Erk‐stimulated cells. In the inducible cell lines, expression of wild‐type form of Sp3 increases VEGF production whereas the S73A form has a reduced potential reflecting its lower transcriptional activity. Altogether our results described a new link between constitutive Erk activity and the regulation of VEGF expression two common denominators implicated in tumor angiogenesis. J. Cell. Physiol. 213: 454–463, 2007. © 2007 Wiley‐Liss, Inc.
Chemical characterization of medium‐chain‐length polyhydroxyalkanoates (PHAs) recovered by enzymatic treatment and ultrafiltration
Authors: Kathiraser Yasotha , Aroua Mohamed Kheireddine , Ramachandran Kadathur B , Tan Irene Kit Ping
Published: August 2007

BACKGROUND: Medium‐chain‐length polyhydroxyalkanoates (PHAs) are biodegradable polyesters accumulated intracellularly as energy resources by bacterial species such as Pseudomonas putida. The most popular method for PHA recovery is solvent extraction using trichloromethane (chloroform) and methyl alcohol (methanol). An alternative method is enzymatic treatment, which eliminates usage of these hazardous solvents. This research focuses on the characterization of PHAs recovered by enzymatic treatments and ultrafiltration. Comparisons are made with conventional solvent extracted PHA.

RESULTS: The purity of PHA in water suspension recovered by enzymatic treatments as analyzed by gas chromatography was 92.6%. Enzymatically recovered PHA was comparable to conventional solvent‐extracted PHA, which had a purity of 95.5%. PHA was further characterized for functional group analysis, structural composition analysis and molecular weight determination. It was found that the molecular weight of the PHA recovered by enzymatic treatment was less than solvent‐extracted PHA, probably due to degradation of the lipopolysaccharide layer. However, functional group and structural composition analyses showed similar results for PHA recovered by both methods.

CONCLUSION: PHAs recovered through enzymatic digestion treatment have good comparability with solvent‐extracted PHAs. Thus enzymatic digestion has great potential as an alternative recovery method. Copyright © 2007 Society of Chemical Industry
Imaging of lung ventilation and respiratory dynamics in a single ventilation cycle using hyperpolarized He‐3 MRI
Authors: Holmes James H. , Korosec Frank R. , Du Jiang , O'Halloran Rafael L. , Sorkness Ronald L. , Grist Thomas M. , Kuhlman Janet E. , Fain Sean B.
Published: August 2007

Purpose

To image respiratory dynamics and three‐dimensional (3D) ventilation during inhalation, breath‐hold, and exhalation for evaluation of obstructive lung disease using a single dose of hyperpolarized (HP) He‐3 during MRI.

Materials and Methods

A single 2D‐3D projections inside Z encoding (PRIZE)‐2D acquisition was performed that consisted of a rapid 2D radial acquisition phase during inhalation of the HP He‐3, a 3D acquisition phase during a breath‐hold interval, and finally the same 2D radial acquisition during a forced exhalation maneuver followed by tidal breathing. The 3D PRIZE acquisition was comprised of radial sampling in the coronal plane and Fourier encoding in the patient's anterior–posterior direction. Nine patients with mild/moderate to severe asthma were studied (two individuals were studied twice) using this technique.

Results

Breath‐hold and dynamic imaging results showed physiological abnormalities and were compared with results from standard spirometry, body plethysmography, and computed tomography (CT). Dynamic images depicted regions of differential gas clearance and trapping observed during and after forced exhalation that were corroborated as regions of air trapping on CT imaging.

Conclusion

The 2D‐3D PRIZE‐2D acquisition allowed for 3D depiction of ventilation during a breath‐hold, as well as detection of gas trapping. Imaging results were confirmed with spirometry, body plethysmography, and CT. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
Three dimensional myoarchitecture of the human tongue determined in vivo by diffusion tensor imaging with tractography
Authors: Gaige Terry A. , Benner Thomas , Wang Ruopeng , Wedeen Van J. , Gilbert Richard J.
Published: August 2007

Purpose

To study the anatomical relationships involving the intrinsic and extrinsic myofiber populations of the human tongue employing diffusion tensor imaging (DTI) with tractography.

Materials and Methods

Images of the human tongue in vivo were obtained using a twice‐refocused spin echo DTI pulse sequence at 1.5T, isotropic 3 × 3 × 3 mm3 voxels, b‐value 500 seconds/mm2, and 90 different diffusion sensitizing gradient directions. Multivoxel tracts were generated along the vectors, corresponding to the directions of maximal diffusion in each voxel. The data was visualized using custom fiber tracking software and images compared with known anatomy.

Results

DTI tractography depicts the complete three‐dimensional (3D) myoarchitecture of the human tongue, specifically demonstrating the geometric relationships between the intrinsic and extrinsic myofiber populations. These results define the manner in which key extrinsic fiber populations merge with the longitudinally‐, transversely‐, and vertically‐aligned intrinsic fibers.

Conclusion

The current results display for the first time the use of DTI tractography in vivo to visualize the complete structural anatomy of the human tongue and allow us to consider fundamental structure‐function relationships. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
Superparamagnetic iron oxides and low molecular weight gadolinium chelates are synergistic for direct visualization of advanced liver fibrosis
Authors: Hughes‐Cassidy Fiona , Chavez Alyssa D. , Schlang Adrienne , Hassanein Tarek , Gamst Anthony , Wolfson Tanya , Sirlin Claude
Published: August 2007

Purpose

To compare the contrast‐to‐noise ratio (CNR) of advanced liver fibrosis on nonenhanced (NE), gadolinium enhanced (Gd), superparamagnetic iron oxides enhanced (SPIO), and combined contrast‐enhanced (CCE) spoiled gradient echoes (SGEs).

Materials and Methods

This retrospective study assessed 83 consecutive patients with cirrhosis and 10 consecutive patients without fibrosis. All patients had NE, Gd, SPIO, and CCE images at 1.5T. A total of six breathhold SGE sequences with varying imaging parameters were assessed. MR images were evaluated qualitatively and, in 15 cirrhotics who underwent liver transplantation, compared to gross pathology. CNR of fibrosis to background liver was compared across sequences and contrast enhancement types.

Results

In cirrhotic patients, CCE images on all sequences showed fibrosis as a meshwork of high‐signal 1‐mm to 3‐mm thick reticulations surrounding 2‐mm to 5‐mm low‐signal regenerative nodules. Fibrosis was less visible on Gd and SPIO images and was barely visible on NE images. CNR was significantly higher for CCE than for NE, Gd, or SPIO images in eight of nine comparisons (P < 0.0001–0.05). The liver had a homogeneous appearance in subjects without fibrosis.

Conclusion

CCE imaging depicts advanced liver fibrosis with higher CNR than NE, Gd, or SPIO SGEs. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
Linear free energy relationships in CN bond dissociations in molecular ions of 4‐substituted N‐(2‐furylmethyl)anilines in the gas phase
Authors: Solano Espinoza Eduardo A. , Stashenko Elena , Martínez Jairo , Mora Uriel , Kouznetsov Vladimir
Published: August 2007

The substituent effect on the reactivity of the CN bond of molecular ions of 4‐substituted N‐(2‐furylmethyl)anilines toward two dissociation pathways was studied. With this aim, six of these compounds were analyzed by mass spectrometry using electron ionization with energies between 7.8 and 69.9 eV. Also, the UB3LYP/6‐31G (d,p) and UHF/6‐31G (d, p) levels of theory were used to calculate the critical energies (reaction enthalpies at 0 K) of the processes that lead to the complementary ions [C5H5O]+ and [M − C5H5O]+, assuming structures that result from the heterolytic and homolytic CN bond cleavages of the molecular ions, respectively. A kinetic approach proposed in the 1960s was applied to the mass spectral data to obtain the relative rate coefficients for both dissociation channels from ratios of the peak intensities of these ions. Linear relationships were obtained between the logarithms of the relative rate coefficients and the calculated critical energies and other thermochemical properties, whose slopes showed to be conditioned by the energy provided to the compounds within the ion source. Moreover, it was found that the dissociation that leads to [C5H5O]+ is a process strongly dependent upon the electron withdrawing or donating properties of the substituent, favored by those factors that destabilize the molecular ion. On the contrary, the dissociation that leads to [M − C5H5O]+ is indifferent to the polar electronic effects of the substituent. The abundance of both products was governed by the rule of Stevenson–Audier, according to which the major ion is the one of less negative electronic affinity. Copyright © 2007 John Wiley & Sons, Ltd.