bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of the spatial arrangement of habitat patches on the development of fish habitat models in the littoral zone of a Canadian Shield lake
Authors: Brind'Amour Anik , Boisclair Daniel
Published: April 2006

We developed fish habitat models in a Canadian Shield lake using (i) a sampling-site approach based on analytical units having a surface area equal to that of sampling sites (S ~ 200 m2), (ii) a constant-multiple approach in which the analytical units constituted grouping of adjacent sampling sites in units of increasing sizes (e.g., 2S or 3S), and (iii) a habitat-patch approach in which only contiguous sampling sites with similar environmental characteristics were merged. The best models explaining within-lake variations in fish density, biomass, and community structure on the littoral zone were obtained using the constant-multiple approach, but the predictive power of these models was highly variable (0 < R2 < 0.9) compared with the habitat-patch approach (0.27 < R2 < 0.49). For these approaches, intrinsic variables (estimated inside the analytical units) explained on average 16%27% of the variations of fish descriptors compared with 6%32% for extrinsic variables (observed outside analytical units or related to the spatial arrangement of habitat characteristics). Our study suggests that habitat patches are reliable analytical units with which to develop fish-habitat models. Our study also indicates that inclusion of variables that refer to landscape characteristics may significantly improve the predictive power of fish habitat models.
Carbon burial and infill rates in small Western Boreal lakes: physical factors affecting carbon storage
Authors: Squires Margaret M , Mazzucchi David , Devito Kevin J
Published: April 2006

Effects of depression depth (ZT), lake surface elevation (ES), catchment area:lake surface area (AT:AO), trophic status, and surficial geology on sediment burial rates in small Western Boreal Plain lakes were assessed using content and chronology of cores from a relatively large and small lake on each of moraine (M), glaciofluvial (GF), and glaciolacustrine (GL) deposits. Aquatic and terrestrial plant and sediment carbon:nitrogen (C:N) suggested most buried C was aquatic. The rate of long-term total C burial averaged 31 g·m2·year1 (range: 084 g·m2·year1); this was recently 79 g·m2·year1 (range: 40180 g·m2·year1) (higher and more variable rates than previously reported for Boreal lakes). Long-term C accrual rate and sediment depth increased with increasing ZT. In each landform, a relatively low base elevation (EB = ES  ZT) lake began accumulating sediment thousands of years before a high EB lake. GF depressions were deeper and had accrued more C·m2 (and infilled) faster than M and GL lakes; a large GF lake had no organic sediment, perhaps because of large groundwater inputs. Increasing AT:AO corresponded with increasing C accrual rates where precipitation and evaporation dominated (surface runoff infrequent) (M and GL) but not where groundwater dominated (GF lakes) lake water budgets, illustrating the importance of landform and depression characteristics in regionalizing lake-C burial estimates.
Effects of low-head barriers on stream fishes: taxonomic affiliations and morphological correlates of sensitive species
Authors: McLaughlin Robert L , Porto Louise , Noakes David LG , Baylis Jeffrey R , Carl Leon M , Dodd Hope R , Goldstein Jon D , Hayes Daniel B , Randall Robert G
Published: April 2006

Low-head barriers used in the control of parasitic sea lamprey (Petromyzon marinus) in the basin of the Laurentian Great Lakes can alter the richness and composition of nontarget fishes in tributary streams. Identification of taxa sensitive to these barriers is an important step toward mitigating these effects. Upstreamdownstream distributions of fishes in 24 pairs of barrier and reference streams from throughout the basin were estimated using electrofishing surveys. For 48 common species from 34 genera and 12 taxonomic families, 819 species, 516 genera, and 27 families showed evidence of being sensitive to barriers, with the variation in number depending on the statistical measure applied. Barriers did not differentially affect species from certain genera or families, nor did they affect species of certain body form. Therefore, taxonomic affiliation and swimming morphology are not useful for predicting sensitivity to barriers for fishes that co-occurred with sea lampreys but were not sampled adequately by our survey. Our estimates of sensitivity will help fisheries managers make sound, defensible decisions regarding the construction, modification (for fish passage), and removal of small, in-stream barriers.
Size-structured patterns of piscivory of the longfin inshore squid (Loligo pealeii) in the mid-Atlantic continental shelf ecosystem
Authors: Hunsicker Mary E , Essington Timothy E
Published: April 2006

The longfin inshore squid (Loligo pealeii) dominates the landings in the USA mid-Atlantic continental shelf region, yet the potential ecological effects of harvesting this species are not known. Because squid feed on a wide variety of prey items, including juvenile stages of commercially important fish species, a full exploration on the predatory role of squid in this ecosystem is warranted. We examined the seasonal diet contents of L. pealeii and evaluated the importance of size constraints in governing patterns of piscivory. Our analyses showed that piscivory was dictated by size constraints, with larger squid demonstrating higher rates of piscivory than small squid. Squid were piscivorous at smaller sizes in the winter and spring than during the summer and autumn. Also, the frequency of piscivory was highest during the winter and spring, coincident with the time period when the number of vulnerable prey species was greatest. Our findings suggest that the frequency and intensity of piscivory are likely to be related to the duration of time that prey are vulnerable to predation, which in turn is dictated by the relative body sizes of L. pealeii and juvenile fishes.
Historical changes in abundance and community structure of warmwater piscivore communities associated with changes in water clarity, nutrients, and temperature
Authors: Robillard M M , Fox M G
Published: April 2006

In this study, we assess changes in the piscivore community of four large, shallow lakes in the Kawartha Lakes region of central Ontario, Canada, over the period from 1980 to 2003 and relate these changes to temporal trends in phosphorus concentration, water clarity, and temperature. Over the 24-year period of data collection, there has been a regional-scale decline in the relative abundance of walleye (Sander vitreus) and an increase in the relative abundance of bass (Micropterus spp.) species. These changes were associated with reductions in phosphorus concentration and increases in water clarity and summer temperature. Results of a comparative field study conducted on 13 regional lakes indicate significant positive associations between concentrations of total phosphorus and chlorophyll a and zooplankton and walleye density. These data suggest that bottom-up effects are limiting walleye abundance either directly or in combination with abiotic conditions that favour bass over walleye.
Comparison and utility of different size-based metrics of fish communities for detecting fishery impacts
Authors: Duplisea Daniel E , Castonguay Martin
Published: April 2006

The use of fish community indicators based on size spectra has become popular in the development of an ecosystem approach to fisheries. Size spectrum theory arose from basic ecological work on energy flow, predatorprey interactions, and biomass standing stock and was later applied to fish communities as lengthfrequency analysis. A multitude of size spectrum indicators have resulted, but it is not clear if they all present similar information. Here we develop a simple framework describing what four size spectra indicators suggest about fish communities, their likely response to fisheries exploitation, their ecological interpretation, and some of their biases. We examined indicators for scientific survey data from six exploited North Atlantic fish communities for the information that they reveal about each community. Each indicator revealed different information and had different biases. Combining indicators for the most impacted system (owing to fisheries and environmental change), the eastern Scotian Shelf, revealed a pattern analogous to Holling's ecological cycle of exploitation, conservation, release, and reorganisation. If this analogy is generally valid, then it suggests that collapsed fish communities are more susceptible to chance events, and recovery is not directly reversible and may not be recoverable (to previous known state) at all if the system moves to an alternative cycle.
Continued disappearance of the benthic amphipod Diporeia spp. in Lake Michigan: is there evidence for food limitation?
Authors: Nalepa Thomas F , Fanslow David L , Foley III Andrew J , Lang Gregory A , Eadie Brian J , Quigley Michael A
Published: April 2006

Benthic surveys were conducted in the southern basin of Lake Michigan and throughout the lake to assess trends in benthic populations, emphasizing recent changes in densities of the benthic amphipod Diporeia spp. and dreissenid mussels. In the southern basin, Diporeia populations declined 89%, 91%, and 45% between 1993 and 2002 at sites <30, 3150, and 5190 m, respectively. Lakewide, the population declined 65% between 19941995 and 2000. Over the same time period, dreissenid densities, particularly Dreissena bugensis, increased. Intensive studies at 45 m sites in the southeastern region examined changes in lipid content, age structure, and benthic food inputs relative to the hypothesis that food limitation was a factor in Diporeia's disappearance. As Diporeia densities declined to zero, lengthweight remained unchanged, and lipid content generally increased. Recruitment still occurred, but the young did not survive to become adults. Based on organic carbon, biogenic silica, and chlorophyll collected in sediment traps and found in the upper sediments, pelagic inputs to the benthic region still occurred. Our field observations and laboratory experiments did not disprove the hypothesis that food limitation from dreissenid filtering activities was the cause of the decline, but direct relationships between the loss of Diporeia and indicators of food availability were difficult to establish.
Empirical analysis and transboundary management for Georges Bank multispecies fishery
Authors: Soboil Mark Lucas , Sutinen Jon G
Published: April 2006

This paper reports the results of a bioeconomic evaluation of alternative management strategies for the Georges Bank transboundary multispecies fishery. Because the distribution of the principal groundfish resources on Georges Bank involves substantial movement and migration across the USCanada boundary, the harvest by one country affects the benefits to the other country. An empirically based model of the transboundary multispecies fishery was built to simulate alternative management strategies imposed by each country. The simulations were used to help determine whether the status quo management is superior to any other strategy and, if not, what other strategies are better in terms of economic performance. Our aim is to determine whether there are combinations of US and Canadian harvest policies that would make both countries better off and whether a “winwin” strategy exists in the fishery. The results suggest that there are winwin strategies in terms of economic benefits, but such strategies may not be legally feasible under current fisheries law.
Long-term trends of bloater (Coregonus hoyi) recruitment in Lake Michigan: evidence for the effect of sex ratio
Authors: Bunnell David B , Madenjian Charles P , Croley II Thomas E
Published: April 2006

Long-term population trends are generally explained by factors extrinsic (e.g., climate, predation) rather than intrinsic (e.g., genetics, maternal effects) to the population. We sought to understand the long-term population dynamics of an important native Lake Michigan prey fish, the bloater Coregonus hoyi. Over a 38-year time series, three 10- to 15-year phases occurred (poor, excellent, and then poor recruitment) without high interannual variability within a particular phase. We used dynamic linear models to determine whether extrinsic (winter and spring temperature, alewife predator densities) or intrinsic factors (population egg production, adult condition, adult sex ratio) explained variation in recruitment. Models that included population egg production, sex ratio, winter and spring temperature, and adult bloater condition explained the most variation. Of these variables, sex ratio, which ranged from 47% to 97% female across the time series, consistently had the greatest effect: recruitment declined with female predominance. Including biomass of adult alewife predators in the models did not explain additional variation. Overall our results indicated that bloater recruitment is linked to its sex ratio, but understanding the underlying mechanisms will require additional efforts.
HIGHER DERIVATIVE OPERATORS AS COUNTERTERMS IN ORBIFOLD COMPACTIFICATIONS
Authors: GHILENCEA DUMITRU , LEE HYUN MIN
Published: April 2006

In the context of 5D N = 1 supersymmetric models compactified on S1/Z2 or S1/(Z2×Z2′) orbifolds and with brane-localized superpotential, higher derivative operators are generated radiatively as one-loop counterterms to the mass of the (brane or zero mode of the bulk) scalar field. It is shown that the presence of such operators which are brane-localised is not related to the mechanism of supersymmetry breaking considered (F-term, discrete or continuous Scherk–Schwarz breaking) and initial supersymmetry does not protect against the dynamical generation of such operators. Since in many realistic models the scalar field is commonly regarded as the Higgs field, and the higher derivative operators seem a generic presence in orbifold compactifications, we stress the importance of these operators for solving the hierarchy problem.
SPIN HALL EFFECT
Authors: SCHLIEMANN JOHN
Published: April 2006

The intrinsic spin Hall effect in semiconductors has developed to a remarkably lively and rapidly growing branch of research in the field of semiconductor spintronics. In this article we give a pedagogical overview on both theoretical and experimental accomplishments and challenges. Emphasis is put on the the description of the intrinsic mechanisms of spin Hall transport in III-V zinc-blende semiconductors and on the effects of dissipation.
ARAGONITE TO CALCITE TRANSFORMATION STUDY BY XRD AND ESR STUDIES OF Mn2+ IN FRESHWATER SNAIL SHELLS: P. CANALICULATA LAMARCK
Authors: UDOMKAN N. , LIMSUWAN P. , CHAIMANEE Y.
Published: April 2006

Electron spin resonance spectroscopy (ESR) was used to study the Mn 2+ ions in snails of P. canaliculata lamarck (PCL). All these shells are abundant in Thailand. Fractions of aragonite and calcite phase in the shells have been approximately determined by ESR. The PCL shell was ground into fine powders and then four samples were separately annealed for 2 h in air at 400°C, 450°C, 500°C and 600°C, respectively. The phase transition from aragonite to calcite was monitored by X-ray diffractometer (XRD) and electron spin resonance spectrometer (ESR). Our results show that unheated PCL sample is mainly made of aragonite with only a small fraction of calcite. Annealing of the PCL powder sample at the temperature more than 450°C has resulted in the irreversible phase transformation from aragonite to calcite. The analysis of their ESR spectra has shown that Mn 2+ ions partially substituted Ca 2+ in the lattices. Finally, the spin Hamiltonian parameters for Mn 2+ distributed in both aragonite and calcite were evaluated. Our detailed ESR spectral analyses of PCL show that Mn 2+ ions enter Ca 2+ sites during a biomineralization process. Typical simulated ESR parameters of PCL-500 of Mn 2+ at a uniaxial site of calcite are gx=gy=2.078(1), gz=1.999(1), Ax=Ay=87.0 G, Az=89.00 G and D=115 G, respectively. It is thus possible to gain some insight of manganese incorporation into the fresh water shells during the biomineralization process.
ANALYTICAL EXPRESSIONS FOR CORRECTION FACTORS FOR NOISE MEASUREMENTS WITH A FOUR-POINT PROBE
Authors: VANDAMME L. K. J. , LEROY G.
Published: April 2006

The linear four-point probe method is useful to measure the resistivity, by passing a current I14 through the outer probes and by measuring the voltage V23 between the inner probes. The contacts are on a line and denoted by 1, 2, 3, 4, respectively. The sheet resistance for thin layers with thickness t is Rsh = ρ/t (Ω). The sheet resistance is measured as Rsh = (V23/I14). C23 where the correction factor is C23 = π/ln2 = 4.53 for t smaller than s, the distance between probe points. In order to characterize the 1/f noise of a film with a four-point probe we need noise correction factors for the calculation of the conductance noise from the voltage noise between the pair of points, where the current is not passed through. Our calculations of the noise correction factors are based on the general theory for conductance noise investigations with four arbitrarily shaped and placed electrodes. Analytical expressions for noise correction factors Fij and fij are derived and compared with experimental results for the three cases. The subscripts of F and f denote the voltage sensor contacts. The following cases are investigated: 1) I14 and V23, 2) I13 and V24 and 3) I12 and V34. The subscripts in I and V denote the current driver contacts and voltage sensor contacts, respectively. From the calculations and experimental results it follows that: i) case1 (I14 and V23) is the best choice in order to suppress a non-intentional noise contribution from the interface between probe tip and layer, ii) the reciprocity relation is applicable to voltage noise due to conductance fluctuations. The voltage noise SV23 that is observed by passing a constant current I14 through the pair of probes 1, 4 is equal to the voltage noise SV14 if we pass the same current through the contacts 2, 3.

The four-point probe method with the noise correction factors can be recommended to investigate e.g., the conductance noise of conductive polymer layers even with an insulating top layer and without the preparation of rectangular samples with perfect noise-free line contacts. The four-point probe can punch an insulating top layer and allows the measurement of sheet resistance and noise. Several tests show that the noise contributions from the interface between probe tip and layer are negligible. The ratio of the conductance (1/f) noise, Cus, normalized for frequency and area and the sheet resistance gives an indication of the degree of percolation in composite conductive layers.
PULMONARY NODULE DETECTION AND VOLUMETRICAL ANALYSIS WITH LOW DOSE PROTOCOLS: PRELIMINARY EXPERIENCE
Authors: ROSSI PIER LUCA , BALDAZZI GIUSEPPE , BERNARDI TERENZIO , PAGAN LAURA , TESTONI GIOVANNI , ZANNOLI ROMANO , GAVELLI GIAMPAOLO
Published: April 2006

Diagnostic accuracy of a Computed Tomography (CT) exam protocol is dependent both on physical parameters of the CT scanner both on radiologist visualization, so it is fundamental to perform a complete characterization of the "diagnostic system" to define optimal protocol. A psycho-physical approach was performed; a CT procedure that requires scanning repetition of the same anatomical district was analyzed, acquiring every CT image sets with a different Low Dose protocol. Images acquired from 20 patients were post-processing shuffled, codified and scored by expert radiologists. Matching this data with effective dose imparted to patient, it is possible to define an optimized CT protocol. The measurements accuracy was assessed by performing analysis of a dedicated phantom with synthetic nodules. Our CT volumetrical analysis show that optimal Low Dose protocol, associated with volume reconstruction algorithm, is accurate to determine nodule with a diameter of Φ > 1.0 cm and variations in nodule diameters of ΔΦ ≈ 5 mm .
AN ENDOCARDIAL ACCELERATION SENSOR FOR MONITORING CARDIAC FUNCTION OF ISCHEMIC HEARTS
Authors: MARCELLI E. , VANOLI E. , MATTERA G. G. , GAGGINI G. , CERCENELLI L. , PLICCHI G.
Published: April 2006

Previous experimental studies demonstrated that in normal hearts, Peak Endocardial Acceleration (PEA), during isovolumic contraction phase, measured with an endocardial sensor (Best, Sorin) in the right ventricle (RV), tracks changes of left ventricular (LV) contractility. Aim of the study: To assess if PEA also tracks LV contractility changes in ischemic hearts resulting from coronary microembolizations (ME). Methods: Under general anaesthesia, six adult beagle dogs (12 ± 2 kg) were instrumented for chronic monitoring of LV pressure, ECG and PEA. Latex beads mixed with fluoroscopy dye were injected into the circumflex coronary artery to cause LV ischemia. Before and after ME, incremental dobutamine infusions were performed to evaluate the contractile response to adrenergic stimulation. Results: A significant correlation between PEA and LVdP /dt max was observed before and after ME. Such a strong correlation was maintained even during adrenergic stimulation (r = 0.83 to 0.99, p < 0.001). The sensor PEA appears to be an effective means for the chronic monitoring of the mechanical function of ischemic hearts.
INTRAVASCULAR ULTRASOUND PALPOGRAPHY: A NEW METHOD FOR THE DETECTION OF THE VULNERABLE PLAQUE
Authors: SAIA FRANCESCO , SCHAAR JOHANNES A. , MASTIK FRITS , DE KORTE CHRIS L. , CORNACCHIA SAMANTHA , DE FEYTER PIM J. , SERRUYS PATRICK W. , VAN DER STEEN ANTONIUS F. W.
Published: April 2006

Acute coronary syndromes originate from atherosclerotic plaque rupture and subsequent developement of coronary thrombosis. Available screening and diagnostic methods are insufficient to identify the atherosclerotic plaques that will rupture and precipitate the coronary event. We developed a new intracoronary diagnostic method based on intravascular ultrasound (IVUS) examination to evaluate the local mechanical properties of atherosclerotic plaques namely IVUS-elastography/palpography. The relationships between local strain, histological features of vulnerability, clinical presentation, and clinical markers of instability were assessed.
IMPLANTABLE SENSORS TO ASSESS CARDIAC FUNCTION
Authors: PLICCHI G. , MARCELLI E. , CERCENELLI L.
Published: April 2006

The quest to discover effective methodologies to monitor the course of disease and response to therapeutic agents in patients with chronic heart failure continues. Clinical trials of specific therapeutic agents have shown efficacy in large groups of patients, but the outcome even with the most effective agents is recognized to be heterogeneous for largely unexplained reasons. The idea that the treatment of individual patients with heart failure could be guided by serial measurements of surrogate end points for mortality and morbidity remains attractive to clinicians. A new approach for clinicians is the guiding of heart failure care by hemodynamic implantable sensors, and in this paper, a brief review of the implantable technologies available to assess cardiac function for monitoring the course of chronic heart failure (CHF) is presented. Early results suggest that measurements arising from these implantable devices should help in guiding the long-term management of CHF patients. Careful consideration of measurements to make, end points to assess, and therapy in control patients will be essential in validating new approaches.
FINITE ELEMENT SIMULATIONS OF THE PHYSIOLOGICAL AORTIC ROOT AND VALVE SPARING CORRECTIONS
Authors: SONCINI MONICA , VOTTA EMILIANO , ZINICCHINO SILVIA , BURRONE VALERIA , FUMERO ROBERTO , MANGINI ANDREA , LEMMA MASSIMO , ANTONA CARLO , REDAELLI ALBERTO
Published: April 2006

A 3-D model of the aortic root was developed consisting of aortic valve, sinus of Valsalva and aortic duct. Through finite element modeling, the mechanical behavior of the valve was investigated simulating four different configurations: physiological (baseline), aneurysmatic and corrected with two different sparing techniques, named after David and Yacoub, respectively. These surgical procedures imply the replacement of the sinus of Valsalva with a synthetic graft, inside which the cusps are resuspended. The final goal of this study consisted in the assessment of the mechanical effects of sinuses aneurysm on the whole root, as well as the effectiveness of the two aforementioned techniques in restoring valve functionality and normal stress values on the root substructures. Based on the assumption of three-leaflet symmetry, only one third of the aortic root was modeled. Two cardiac cycles were simulated and the mechanical behavior of the aortic root was evaluated in terms of stress pattern, contact pressure and contact areas observed during leaflets coaptation and when contact between the leaflet and the graft occurs. Both the sparing techniques are able to restore coaptation of the aortic valve, but for the David procedure, contact between the leaflet and the graft wall was detected.
BIOMECHANICS OF THE INTACT AND REPLACED HUMAN ANKLE JOINT
Authors: CORAZZA FEDERICO , PARENTI-CASTELLI VINCENZO , STAGNI RITA , CAPPELLO ANGELO , O'CONNOR JOHN J. , LEARDINI ALBERTO
Published: April 2006

The main objective of the study was to develop advanced biomechanical models of the intact human ankle complex. It was also aimed at designing a total ankle replacement which would better reproduce the physiological function of the joint. Passive flexion was analyzed in a number of lower-leg preparations with stereophotogrammetry and radiostereometry. The articular surfaces and fibres within the calcaneofibular and tibiocalcaneal ligaments were observed to prescribe the changing positions of bones, ligaments and instantaneous axis of rotation. Joint motion included rolling as well as sliding. Computer-based models elucidated this kinematics at the intact joint, and how changing positions of the centre of rotation and muscle lines of action affect lever arm length at different flexion angles. The mechanical response of the joint to anterior drawer and talar tilt tests was explained in terms of fibre recruitment. The experimental evidence and the geometrical models gave the basis for the design of a novel ankle replacement. A three-component, convex-tibia prosthesis was developed with articular surface shapes that are compatible with the geometry of the ligaments. The proposed prosthesis based on ligament/shape compatibility is showing encouraging results in initial implantation.
Saucer-shaped sill with lobate morphology revealed by 3D seismic data: implications for resolving a shallow-level sill emplacement mechanism
Authors: Hansen Dorthe Møller , Cartwright Joe
Published: April 2006

We use 3D seismic data to describe the 3D geometry of a large igneous intrusion, the Solsikke Compound Sill, and address a number of issues related to sill emplacement. The Solsikke Compound Sill formed by amalgamation of a number of sills and exhibits a complex internal morphology dominated by saucer-shaped depressions and linear discontinuities. One of the saucer-shaped sub-elements of the compound sill, the Solsikke Lobate Sill, has a previously unrecognized morphology. It has a basal feeder and consists of a bifurcating network of interlinked lobe-shaped sill segments. We propose two models for the development of this intrusive style based on analogues from igneous systems and hydrofracturing experiments. The lobate pattern indicates that the Solsikke Lobate Sill was fed at its deepest point and adopted its geometry through outwards and upwards propagation. The feeder location is coincident with a fault intersection, suggesting that magma transport from the underlying source exploited the zone surrounding the intersection.
Geometry and regional significance of Neoproterozoic (Cadomian) structures of the Narcea Antiform, NW Spain
Authors: Díaz García F.
Published: April 2006

The Narcea Antiform is located at the hinterland-to-foreland transition of the Variscan belt in the NW of the Iberian massif. It consists of an antiformal stack of fault-propagation folds that developed in the hanging wall of allochthonous thrust sheets during the first Variscan deformation event in the Palaeozoic rocks. The Neoproterozoic Narcea Slates Formation, cropping out in the core of the Narcea Antiform, records a Cadomian deformation event that formed large asymmetric NW-vergent folds, with related axial planar cleavage, developed in the lower greenschist facies. These folds are truncated by the Lower Cambrian angular unconformity. Lower Cambrian conglomerates contain pebbles with predepositional microstructures that are widespread in the underlying Neoproterozoic rocks. The Narcea Antiform provides valuable information concerning major tectonic Cadomian events. The large-scale, near-recumbent Cadomian folds developed between 560 and 540 Ma. Top-to-the-NW kinematics can be deduced for the Cadomian plate convergence (transverse to the Variscan convergence) in present coordinates. It was followed shortly afterwards by large displacements along the northern Gondwana margin that resulted in its accretion alongside the essentially undeformed Neoproterozoic rocks of the Central Iberian Zone before Early Cambrian times.
Immunomodulation by 17β-estradiol in bivalve hemocytes
Authors: Canesi Laura , Ciacci Caterina , Lorusso Lucia Cecilia , Betti Michele , Guarnieri Tiziana , Tavolari Simona , Gallo Gabriella
Published: April 2006

In mammals, estrogens have dose- and cell-type-specific effects on immune cells and may act as pro- and anti-inflammatory stimuli, depending on the setting. In the bivalve mollusc Mytilus, the natural estrogen 17β-estradiol (E2) has been shown to affect neuroimmune functions. We have investigated the immunomodulatory role of E2 in Mytilus hemocytes, the cells responsible for the innate immune response. E2 at 5–25 nM rapidly stimulated phagocytosis and oxyradical production in vitro; higher concentrations of E2 inhibited phagocytosis. E2-induced oxidative burst was prevented by the nitric oxide (NO) synthase inhibitor NG-monomethyl-l-arginine and superoxide dismutase, indicating involvement of NO and O2−; NO production was confirmed by nitrite accumulation. The effects of E2 were prevented by the antiestrogen tamoxifen and by specific kinase inhibitors, indicating a receptor-mediated mechanism and involvement of p38 MAPK and PKC. E2 induced rapid and transient increases in the phosphorylation state of PKC, as well as of a aCREB-like (cAMP responsive element binding protein) transcription factor, as indicated by Western blot analysis with specific anti-phospho-antibodies. Localization of estrogen receptor-α- and -β-like proteins in hemocytes was investigated by immunofluorescence confocal microscopy. The effects of E2 on immune function were also investigated in vivo at 6 and 24 h in hemocytes of E2-injected mussels. E2 significantly affected hemocyte lysosomal membrane stability, phagocytosis, and extracellular release of hydrolytic enzymes: lower concentrations of E2 resulted in immunostimulation, and higher concentrations were inhibitory. Our data indicate that the physiological role of E2 in immunomodulation is conserved from invertebrates to mammals.
Functional MRI of the kidney: tools for translational studies of pathophysiology of renal disease
Authors: Prasad Pottumarthi V.
Published: April 2006

Magnetic resonance imaging (MRI) provides exquisite anatomic detail of various organs and is capable of providing additional functional information. This combination allows for comprehensive diagnostic evaluation of pathologies such as ischemic renal disease. Noninvasive MRI techniques could facilitate translation of many studies performed in controlled animal models using technologies that are invasive to humans. Such a translation is being recognized as essential because many proposed interventions and drugs that prove efficacious in animal models fail to do so in humans. In this article, we review the state-of-the-art functional MRI technique as applied to the kidneys.
Microbial nucleic acids pay a Toll in kidney disease
Authors: Pawar Rahul D. , Patole Prashant S. , Wörnle Markus , Anders Hans-Joachim
Published: April 2006

Nucleic acids provide more than the genetic code that determines the morphological and functional phenotype of microbes and eukaryotes. In fact, nucleic acids have immunomodulatory functions as they are recognized by a set of pattern-recognition receptors that initiate and modulate immune responses in the host. Toll-like receptor (TLR)-3 recognizes double-stranded RNA, TLR7 and TLR8 recognize single-stranded RNA, CpG-DNA is a ligand for TLR9, and all of these TLRs are expressed in the nephritic kidney. In this review, we summarize recent advances in this field and discuss new hypotheses for the pathogenesis of kidney diseases that are triggered by infectious organisms.
Role of renal cortical cyclooxygenase-2 expression in hyperfiltration in rats with high-protein intake
Authors: Yao Bing , Xu Jie , Qi Zhonghua , Harris Raymond C. , Zhang Ming-Zhi
Published: April 2006

Renal cortical cyclooxygenase-2 (COX-2) is restricted to the macula densa and adjacent cortical thick ascending limbs (MD/cTALH). Renal cortical COX-2 increases in response to diabetes and renal ablation, both of which are characterized by hyperfiltration and reduced NaCl delivery to the MD due to increased proximal NaCl reabsorption. High-protein intake also induces hyperfiltration and decreases NaCl delivery to the MD due to increased NaCl reabsorption proximally. We investigated whether high protein induces cortical COX-2 and whether cortical COX-2 contributes to high protein-induced hyperfiltration and increased intrarenal renin biosynthesis. Cortical COX-2 increased after protein loading but decreased after protein restriction. COX-2 inhibition attenuated high protein-induced hyperfiltration but had no effect on high protein-induced intrarenal renin elevation. Therefore, induction of cortical COX-2 contributed to high protein-induced hyperfiltration but not intrarenal renin elevation. In the kidney cortex, neuronal nitric oxide synthase (nNOS) is also localized to the MD, and interactions between intrarenal nNOS and COX-2 systems have been proposed. Cortical COX-2 elevation seen in salt restriction was blocked by nNOS inhibiton. Cortical nNOS expression also increased after protein loading, and inhibition of nNOS activity completely reversed high protein-induced cortical COX-2 elevation and hyperfiltration. These results indicate that NO is a mediator of high protein-induced cortical COX-2 elevation and suggest that both intrarenal nNOS and COX-2 systems appear to regulate afferent arteriolar tone and subsequent hyperfiltration seen in high-protein intake.
Splenectomy impairs diffusive oxygen transport in the lung of dogs
Authors: Dane D. Merrill , Hsia Connie C. W. , Wu Eugene Y. , Hogg Richard T. , Hogg Deborah C. , Estrera Aaron S. , Johnson Robert L.
Published: April 2006

The spleen acts as an erythrocyte reservoir in highly aerobic species such as the dog and horse. Sympathetic-mediated splenic contraction during exercise reversibly enhances convective O2 transport by increasing hematocrit, blood volume, and O2-carrying capacity. Based on theoretical interactions between erythrocytes and capillary membrane (Hsia CCW, Johnson RL Jr, and Shah D. J Appl Physiol 86: 1460–1467, 1999) and experimental findings in horses of a postsplenectomy reduction in peripheral O2-diffusing capacity (Wagner PD, Erickson BK, Kubo K, Hiraga A, Kai M, Yamaya Y, Richardson R, and Seaman J. Equine Vet J 18, Suppl: 82–89, 1995), we hypothesized that splenic contraction also augments diffusive O2 transport in the lung. Therefore, we have measured lung diffusing capacity (DlCO) and its components during exercise by a rebreathing technique in six adult foxhounds before and after splenectomy. Splenectomy eliminated exercise-induced polycythemia, associated with a 30% reduction in maximal O2 uptake. At any given pulmonary blood flow, DlCO was significantly lower after splenectomy owing to a lower membrane diffusing capacity, whereas pulmonary capillary blood volume changed variably; microvascular recruitment, indicated by the slope of the increase in DlCO with respect to pulmonary blood flow, was also reduced. We conclude that splenic contraction enhances both convective and diffusive O2 transport and provides another compensatory mechanism for maintaining alveolar O2 transport in the presence of restrictive lung disease or ambient hypoxia.
Calmodulin Regulates Current Density and Frequency-Dependent Inhibition of Sodium Channel Nav1.8 in DRG Neurons
Authors: Choi Jin-Sung , Hudmon Andy , Waxman Stephen G. , Dib-Hajj Sulayman D.
Published: April 2006

Sodium channel Nav1.8 produces a slowly inactivating, tetrodotoxin-resistant current, characterized by recovery from inactivation with fast and slow components, and contributes a substantial fraction of the current underlying the depolarizing phase of the action potential of dorsal root ganglion (DRG) neurons. Nav1.8 C-terminus carries a conserved calmodulin-binding isoleucine–glutamine (IQ) motif. We show here that calmodulin coimmunoprecipitates with endogenous Nav1.8 channels from native DRG, suggesting that the two proteins can interact in vivo. Treatment of native DRG neurons with a calmodulin-binding peptide (CBP) reduced the current density of Nav1.8 by nearly 65%, without changing voltage dependency of activation or steady-state inactivation. To investigate the functional role of CaM binding to the IQ motif in the Nav1.8 C-terminus, the IQ dipeptide was substituted by DE; we show that this impairs the binding of CaM to the IQ motif. Mutant Nav1.8IQ/DE channels produce currents with roughly 50% amplitude, but with unchanged voltage dependency of activation and inactivation when expressed in DRG neurons from Nav1.8-null mice. We also show that blocking the interaction of CaM and Nav1.8 using CBP or the IQ/DE substitution causes a buildup of inactivated channels and, in the case of the IQ/DE mutation, stimulation even at a low frequency of 0.1 Hz significantly enhances the frequency-dependent inhibition of the Nav1.8 current. This study presents, for the first time, evidence that calmodulin associates with a sodium channel, Nav1.8, in native neurons, and demonstrates a regulation of Nav1.8 currents that can significantly affect electrogenesis of DRG neurons in which Nav1.8 is normally expressed.
Cloning and functional characterization of a superfamily of microbial inwardly rectifying potassium channels
Authors: Sun Si , Gan Jo Han , Paynter Jennifer J. , Tucker Stephen J.
Published: April 2006

Our understanding of the mammalian inwardly rectifying family of K+ channels (Kir family) has recently been advanced by X-ray crystal structures of two homologous prokaryotic orthologs (KirBac1.1 and KirBac3.1). However, the functional properties of these KirBac channels are still poorly understood. To address this problem, we cloned and characterized genes encoding KirBac orthologs from a wide variety of different prokaryotes and a simple unicellular eukaryote. The functional properties of these KirBacs were then examined by growth complementation in a K+ uptake-deficient strain of Escherichia coli (TK2420). Whereas some KirBac genes exhibited robust growth complementation, others either did not complement or showed temperature-dependent complementation including KirBac1.1 and KirBac3.1. In some cases, KirBac expression was also toxic to the growth of E. coli. The KirBac family exhibited a range of sensitivity to the K+ channel blockers Ba2+ and Cs+ as well as differences in their ability to grow on very low-K+ media, thus demonstrating major differences in their permeation properties. These results reveal the existence of a functionally diverse superfamily of microbial KirBac genes and present an excellent resource for the structural and functional analysis of this class of K+ channels. Furthermore, the complementation assay used in this study provides a simple and robust method for the functional characterization of a range of prokaryotic K+ channels that are difficult to study by traditional methods.
Maps of Odorant Molecular Features in the Mammalian Olfactory Bulb
Authors: Mori Kensaku , Takahashi Yuji K. , Igarashi Kei M. , Yamaguchi Masahiro
Published: April 2006

The olfactory bulb (OB) is the first relay station of the central olfactory system in the mammalian brain and contains a few thousand glomeruli on its surface. Because individual glomeruli represent a single odorant receptor, the glomerular sheet of the OB forms odorant receptor maps. This review summarizes the emerging view of the spatial organization of the odorant receptor maps. Recent studies suggest that individual odorant receptors are molecular-feature detecting units, and so are individual glomeruli in the OB. How are the molecular-feature detecting units spatially arranged in the glomerular sheet? To characterize the molecular-feature specificity of an individual glomerulus, it is necessary to determine the molecular receptive range (MRR) of the glomerulus and to compare the molecular structure of odorants within the MRR. Studies of the MRR mapping show that 1) individual glomeruli typically respond to a range of odorants that share a specific combination of molecular features, 2) each glomerulus appears to be unique in its MRR property, and 3) glomeruli with similar MRR properties gather together in proximity and form molecular-feature clusters. The molecular-feature clusters are located at stereotypical positions in the OB and might be part of the neural representation of basic odor quality. Detailed studies suggest that the glomerular sheet represents the characteristic molecular features in a systematic, gradual, and multidimensional fashion. The molecular-feature maps provide a basis for understanding how the olfactory cortex reads the odor maps of the OB.
Cytokines in Atherosclerosis: Pathogenic and Regulatory Pathways
Authors: Tedgui Alain , Mallat Ziad
Published: April 2006

Atherosclerosis is a chronic disease of the arterial wall where both innate and adaptive immunoinflammatory mechanisms are involved. Inflammation is central at all stages of atherosclerosis. It is implicated in the formation of early fatty streaks, when the endothelium is activated and expresses chemokines and adhesion molecules leading to monocyte/lymphocyte recruitment and infiltration into the subendothelium. It also acts at the onset of adverse clinical vascular events, when activated cells within the plaque secrete matrix proteases that degrade extracellular matrix proteins and weaken the fibrous cap, leading to rupture and thrombus formation. Cells involved in the atherosclerotic process secrete and are activated by soluble factors, known as cytokines. Important recent advances in the comprehension of the mechanisms of atherosclerosis provided evidence that the immunoinflammatory response in atherosclerosis is modulated by regulatory pathways, in which the two anti-inflammatory cytokines interleukin-10 and transforming growth factor-β play a critical role. The purpose of this review is to bring together the current information concerning the role of cytokines in the development, progression, and complications of atherosclerosis. Specific emphasis is placed on the contribution of pro- and anti-inflammatory cytokines to pathogenic (innate and adaptive) and regulatory immunity in the context of atherosclerosis. Based on our current knowledge of the role of cytokines in atherosclerosis, we propose some novel therapeutic strategies to combat this disease. In addition, we discuss the potential of circulating cytokine levels as biomarkers of coronary artery disease.
On n‐normed spaces
Authors: Gunawan Hendra , Mashadi M.
Published: April 2006

Given an n‐normed space with n ≥ 2, we offer a simple way to derive an (n − 1)‐norm from the n‐norm and realize that any n‐normed space is an (n − 1)‐normed space. We also show that,
in certain cases, the (n − 1)‐norm can be derived from the
n‐norm in such a way that the convergence and completeness in
the n‐norm is equivalent to those in the derived (n − 1)‐norm. Using this fact, we prove a fixed point theorem for some
n‐Banach spaces.
Development of Heart Failure in Chronic Hypertensive Dahl Rats
Authors: Klotz Stefan , Hay Ilan , Zhang Geping , Maurer Mathew , Wang Jie , Burkhoff Daniel
Published: April 2006

The impact of hypertension on left ventricular (LV) structure, pump function, and heart failure in Dahl salt-sensitive rats is poorly characterized but hypothesized to yield insights into the pathophysiology of heart failure with normal or preserved ejection fraction. Eighty Dahl salt-sensitive rats were fed either a high-salt (HS) or low-salt (LS, controls) diet starting at age 7 weeks. Ventricular properties were measured by echocardiography, hemodynamics and end-systolic and end-diastolic pressure-volume relationships (ESPVR and EDPVR, respectively). Compared with LS controls, HS rats developed severe hypertension and LV hypertrophy. At week 12, HS rats developed passive diastolic dysfunction (leftward/upward shifted EDPVR, increased chamber stiffness) with reductions in end-diastolic volume. However, the ESPVR also shifted upward (enhanced end-systolic function) so that overall pump function was enhanced compared with LS, and there was no change in end-diastolic pressure (EDP). At 16 and 20 weeks, HS hearts enlarged so that end-diastolic volumes and EDPVRs became similar to the respective age-matched LS controls. Concomitantly, the ESPVRs and overall pump function curves also moved toward controls, and ejection fraction declined. Despite normal or enhanced overall pump function at these times, EDP and wet lung weight increased, indicative of development of heart failure. In the Dahl salt-sensitive rat, which pathophysiologically retains salt and water, the development of heart failure (increased EDP and wet lung weight) is dissociated from changes in passive diastolic and active systolic properties. These observations suggest that a volume overload sate plays an important pathophysiological role in development of heart failure despite preserved overall ventricular pump function in this model of chronic hypertension.
New Mass Spectrometric Assay for Angiotensin-Converting Enzyme 2 Activity
Authors: Elased Khalid M. , Cunha Tatiana S. , Gurley Susan B. , Coffman Thomas M. , Morris Mariana
Published: April 2006

A novel assay was developed for evaluation of mouse angiotensin-converting enzyme (ACE) 2 and recombinant human ACE2 (rACE2) activity. Using surface-enhanced laser desorption/ionization time of flight mass spectrometry (MS) with ProteinChip Array technology, ACE1 and ACE2 activity could be measured using natural peptide substrates. Plasma from C57BL/6 mice, kidney from wild-type and ACE2 knockout mice, and rACE2 were used for assay validation. Plasma or tissue extracts were incubated with angiotensin I (Ang I; 1296m/z) or angiotensin II (Ang II; 1045m/z). Reaction mixtures were spotted onto the ProteinChips WCX2 and peptides detected using surface-enhanced laser desorption/ionization time of flight MS. MS peaks for the substrates, Ang I and Ang II, and the generated peptides, Ang (1-7) and Ang (1-9), were monitored. The ACE2 inhibitor MLN 4760 (0.01 to 100 μmol/L) significantly inhibited rACE2 activity (IC50=3 nmol/L). Ang II was preferably cleaved by rACE2 (km=5 μmol/L), whereas Ang I was not a good substrate for rACE2. There was no detectable ACE2 activity in plasma. Assay specificity was validated in a model of ACE2 gene deletion. In kidney extract from ACE2-deficient mice, there was no generation of Ang (1-7) from Ang II. However, Ang (1-7) was produced when Ang I was used as a substrate. In conclusion, we developed a specific and sensitive assay for ACE2 activity, which used the natural endogenous peptide substrate Ang II. This approach allows for the rapid screening for ACE2, which has applications in drug testing, high-throughput enzymatic assays, and identification of novel substrates/inhibitors of the renin-angiotensin system.