JOURNAL OF CLINICAL PERIODONTOLOGY, Issue 4 2001
A case report with 3-year follow-up
Abstract Background, aims: The purpose of the present case report was to present 2 ways of treating recession in a periodontal patient combined with regular pocket elimination surgery. The techniques used enabled the operator to reduce the number of surgical sessions and clinically evaluate the 3-year coverage of gingival recessions using a subpedicle connective tissue graft. Methods: Surgery consisted of pocket elimination procedures to treat adult periodontitis as a way to harvest connective tissue to be placed in the areas of recession. The grafted tissue was covered by the primary flap or left uncovered in a pouch, according to 2 different techniques described in the literature. Results: In this case, we observed that, with this approach, we were successful in reducing the number of surgical session as well as achieving objective and subjective goals of therapy in treated areas. Zusammenfassung Mit der Präsentation dieses Fallberichtes sollen 2 Methoden zur Rezessionsdeckung bei Parodontitispatienten in Kombination mit chirurgischer Taschenelimination vorgestellt werden. Die Anwendung dieser Methoden machte es möglich, die Zahl der operativen Eingriffe zu reduzieren. Die klinische Rezessionsdeckung durch subepitheliale Bindegewebstransplantate wurde über 3 jahre nachverfolgt. Die parodontalchirurgische Therapie bestand aus einem Verfahren zur Taschenelimination (distale Keilexzion, apikaler Verschiebelappen bei Mobilisation eines Spaltlappens) bei der Behandlung von Erwachsenenparodontitis. Dabei wurden Bindegewebstransplantate gewonnen, die zur Rezessionsdeckung genutzt werden konnten. Die Transplantate wurden entweder mit einem Lappen gedeckt (nach Harris modifizierte Langer-Technik) oder ungedeckt in einer Tasche ("Envelope"-Technik) belassen. In dem präsentierten Fall konnten die Zahl der operativen Eingriffe gesenkt und dabei objektive und subjektive Therapieziele erreicht werden. Résumé L'intérèt de ce rapport de cas est de présenter 2 façons de traiter des récessions chez un patient atteint de maladie parodontale en association avec une chirurgie normale d'élimination des poches. Les techniques utilisées permettent à l'opérateur de réduire le nombre de temps opératoires et nous évaluons cliniquement le recouvrement sur 3 ans des récessions gingivales en utilisant une greffe de tissus conjonctif sous pédiculée. La chirurgie consiste à utiliser les procédures d'élimination des poches, pour traiter la parodontite de l'adulte, comme moyens de prélever du tissus conjonctif qui sera placé sur les zones de récessions. Le tissus greffé est recouvert par le lambeau primaire ou laisséà découvert dans une enveloppe, selon 2 differentes techniques décrites dans la litterature. Dans ce cas, nous avons observé que, avec cette approche, nous réduisions avec succés le nombre de temps opératoires et que nos objectifs de traitement objectifs et subjectifs étaient atteints dans les zones traitées. [source]

Analytical Model for Predicting Thermal Bridge Effects due to Vacuum Insulation Panel Barrier Envelopes,

BAUPHYSIK, Issue 1 2008
Martin Tenpierik ir. arch.
Because of a necessity for sustainability and thus for a reduction of the amount of primary energy generated with fossil fuels, vacuum insulation panels (VIP) have recently caught the attention of practitioners in the building industry. The reduction of layer thickness may be considered among the most promising features for large-scale application of VIPs in buildings. The high barrier laminate (or casing) with relatively high thermal conductivity envelops the core material, thus introducing a thermal bridge at the panel edges and corners. Especially for barrier laminates containing ,thick' metal foils, the thermal bridge effect needs to be considered thoughtfully. In this contribution analytical models are presented which on the one hand allow rapid estimation of the VIP's overall thermal performance and on the other hand show the influence of material and geometric parameters on this performance. The analytical models are validated through numerical simulations. Rechenmodell zur Vorhersage von Wärmebrückeneffekten an der Hülle aus Hochbarrierefolien von Vakuum-Isolations-Paneelen (VIP). Aufgrund der Notwendigkeit von nachhaltigem Bauen und Energieeinsparung wird zunehmend der Einsatz von Vakuum-Isolations-Paneelen (VIP) zur Wärmedämmung im Bauwesen erwogen, insbesondere ist damit die erhebliche Reduzierung der Wärmedämmschichtdicke möglich. Die Umhüllung aus Hochbarrierefolien erfordert allerdings die Berücksichtigung der Wärmebrückenwirkung. Der vorliegende Beitrag stellt Berechnungsmodelle vor, welche einerseits die schnelle Abschätzung des thermischen Verhaltens von VIP-Elementen ermöglichen und andererseits den Einfluss der Geometrie und Konstruktion der Elemente aufzeigen. Die Berechnungsmodelle wurden anhand von Simulationen validiert. [source]

Geodesic-Controlled Developable Surfaces for Modeling Paper Bending

COMPUTER GRAPHICS FORUM, Issue 3 2007
Pengbo Bo
Abstract We present a novel and effective method for modeling a developable surface to simulate paper bending in interactive and animation applications. The method exploits the representation of a developable surface as the envelope of rectifying planes of a curve in 3D, which is therefore necessarily a geodesic on the surface. We manipulate the geodesic to provide intuitive shape control for modeling paper bending. Our method ensures a natural continuous isometric deformation from a piece of bent paper to its flat state without any stretching. Test examples show that the new scheme is fast, accurate, and easy to use, thus providing an effective approach to interactive paper bending. We also show how to handle non-convex piecewise smooth developable surfaces. [source]

The Perspective Silhouette of a Canal Surface

COMPUTER GRAPHICS FORUM, Issue 1 2003
Ku-Jin Kim
We present an efficient and robust algorithm for parameterizing the perspective silhouette of a canal surface and detecting each connected component of the silhouette. A canal surface is the envelope of a moving sphere with varying radius, defined by the trajectoryC(t)of its center and a radius functionr(t). This moving sphere,S(t), touches the canal surface at a characteristic circleK(t). We decompose the canal surface into a set of characteristic circles, compute the silhouette points on each characteristic circle, and then parameterize the silhouette curve. The perspective silhouette of the sphereS(t)from a given viewpoint consists of a circleQ(t); by identifying the values oftat whichK(t)andQ(t)touch, we can find all the connected components of the silhouette curve of the canal surface. ACM CSS: I.3.7 Computer Graphics,Three Dimensional Graphics and Realism [source]

Identification of Modal Combinations for Nonlinear Static Analysis of Building Structures

COMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 4 2004
Sashi K. Kunnath
An increasingly popular analytical method to establish these demand values is a "pushover" analysis in which a model of the building structure is subjected to an invariant distribution of lateral forces. Although such an approach takes into consideration the redistribution of forces following yielding of sections, it does not incorporate the effects of varying dynamic characteristics during the inelastic response. Simple modal combination schemes are investigated in this article to indirectly account for higher mode effects. Because the modes that contribute to deformations may be different from the modes that contribute to forces, it is necessary to identify unique modal combinations that provide reliable estimates of both force and deformation demands. The proposed procedure is applied to typical moment frame buildings to assess the effectiveness of the methodology. It is shown that the envelope of demands obtained from a series of nonlinear static analysis using the proposed modal-combination-based lateral load patterns results in better estimation of inter-story drift, a critical parameter in seismic evaluation and design. [source]

The Impact of a Brief Expectation Survey on Parental Satisfaction in the Pediatric Emergency Department

ACADEMIC EMERGENCY MEDICINE, Issue 12 2006
Christopher D. Spahr MD
Abstract Objectives To determine the effect of physician knowledge of parental expectations on satisfaction with emergency department (ED) care. Methods This was a prospective, controlled, interventional trial involving parents of children presenting to a children's hospital ED. Parents completed an expectation survey on arrival, which was either immediately placed back in the enrollment envelope (control) or shown to the physician caring for the child (intervention). The physician was instructed to initial the expectation survey to acknowledge receipt of the survey. Parents then completed a satisfaction survey at discharge. The primary outcomes were differences in satisfaction with physician review of the expectation survey, as measured by 1) parental ratings of overall care and 2) their willingness to recommend the ED to others. A third (baseline) group completed only a satisfaction survey at discharge. Results A total of 614 (66%) of the 930 enrolled parents completed the study. Intention-to-treat analysis did not show a significant increase in parental satisfaction ratings for either overall care or recommend the ED; however, only 42% of the intervention group surveys had documented physician review. When these initialed surveys were compared with the control group in a per-protocol analysis, there was a significant improvement in parental satisfaction. There were no differences between the control and baseline groups, indicating no effect of the expectation survey completion on satisfaction. Conclusions Physician knowledge of written parental expectations may improve parental satisfaction during an ED visit. Further work is needed to overcome the barriers to physician review of the expectation survey to maximize parent satisfaction. [source]

Regulation of early response genes in pancreatic acinar cells: external calcium and nuclear calcium signalling aspects

ACTA PHYSIOLOGICA, Issue 1 2009
N. Fedirko
Abstract Nuclear calcium signalling has been an important topic of investigation for many years and some aspects have been the subject of debate. Our data from isolated nuclei suggest that the nuclear pore complexes (NPCs) are open even after depletion of the Ca2+ store in the nuclear envelope (NE). The NE contains ryanodine receptors (RyRs) and Ins(1,4,5)P3 receptors [Ins(1,4,5)P3Rs], most likely on both sides of the NE and these can be activated separately and independently: the RyRs by either NAADP or cADPR, and the Ins(1,4,5)P3Rs by Ins(1,4,5)P3. We have also investigated the possible consequences of nuclear calcium signals: the role of Ca2+ in the regulation of immediate early genes (IEG): c-fos, c-myc and c-jun in pancreatic acinar cells. Stimulation with Ca2+ -mobilizing agonists induced significant increases in levels of expression. Cholecystokinin (CCK) (10 nm) evoked a substantial rise in the expression levels, highly dependent on external Ca2+: the IEG expression level was lowest in Ca2+ -free solution, increased at the physiological level of 1 mm [Ca2+]o and was maximal at 10 mm [Ca2+]o, i.e.: 102 ± 22% and 163 ± 15% for c-fos; c-myc ,73 ± 13% and 106 ± 24%; c-jun ,49 ± 8% and 59 ± 9% at 1 and 10 mm of extracellular Ca2+ respectively. A low CCK concentration (10 pm) induced a small increase in expression. We conclude that extracellular Ca2+ together with nuclear Ca2+ signals induced by CCK play important roles in the induction of IEG expression. [source]

The Drosophila nucleoporin gene nup154 is required for correct microfilament dynamics and cell death during oogenesis

CYTOSKELETON, Issue 8 2007
Maria Giovanna Riparbelli
Abstract The Drosophila nucleoporin gene nup154 is required in both male and female germline for successful gametogenesis. Mutant flies lack differentiated sperm and lay abnormal eggs. We demonstrated that the egg phenotype was associated with specific alterations of the actin cytoskeleton at different stages of oogenesis. Actually, mutant egg chambers displayed an abnormal organization of both subcortical microfilaments and cytoplasmic actin bundles, that led to defective nurse cell dumping. TUNEL analysis also showed that the dumpless phenotype was associated with delayed apoptosis. The nup154 gene product was localized by conventional immunofluorescence microscopy to the nuclear envelope in a distinct punctuate pattern, characteristic of nuclear pore complex components. TEM analysis revealed that the protein was mainly distributed along filamentous structures that extended radially on the nuclear side of the pore, suggesting that Nup154 could be an integral component of the basket filaments associated with the nuclear pore complexes. We propose that Nup154 is necessary for correct nuclear pore complex functions and that the proper regulation of the actin cytoskeleton dynamics strongly relies upon nuclear pore integrity. Cell Motil. Cytoskeleton 2007. © 2007 Wiley-Liss, Inc. [source]

Dynamics of the endoplasmic reticulum during early development of Drosophila melanogaster

CYTOSKELETON, Issue 3 2003
Yves Bobinnec
Abstract In this study, we analyze for the first time endoplasmic reticulum (ER) dynamics and organization during oogenesis and embryonic divisions of Drosophila melanogaster using a Protein Disulfide Isomerase (PDI) GFP chimera protein. An accumulation of ER material into the oocyte takes place during the early steps of oogenesis. The compact organization of ER structures undergoes a transition to an expanded reticular network at fertilization. At the syncytial stage, this network connects to the nuclear envelope as each nucleus divides. Time-lapse confocal microscopy on PDI transgenic embryos allowed us to characterize a rapid redistribution of the ER during the mitotic phases. The ER network is massively recruited to the spindle poles in prophase. During metaphase most of the ER remains concentrated at the spindle poles and shortly thereafter forms several layers of membranes along the ruptured nuclear envelope. Later, during telophase an accumulation of ER material occurs at the spindle equator. We also analyzed the subcellular organization of the ER network at the ultrastructural level, allowing us to corroborate the results from confocal microscopy studies. This dynamic redistribution of ER suggests an unexpected regulatory function for this organelle during mitosis. Cell Motil. Cytoskeleton 54:217,225, 2003. © 2003 Wiley-Liss, Inc. [source]

The management of mandibular body fractures in young children

DENTAL TRAUMATOLOGY, Issue 6 2009
Dror Aizenbud
Treatment principles of this fracture type differ from that of adults due to concerns regarding mandibular growth processes and dentition development. The goal of this fracture treatment is to restore the underlying bony architecture to its preinjury position in a stable fashion as non-invasively as possible and with minimal residual esthetic and functional impairment. The management of mandibular body fractures in children depends on the fracture type and the stage of skeletal and dental development; treatment modalities range from conservative non-invasive, through closed reduction and immobilization methods to open reduction with internal fixation. Disruption of the periosteal envelope of the mandibular body may have an unpredictable effect on growth. Thus, if intervention is required closed reduction is favored. [source]

Molecular cloning and sequence analysis of an ascidian egg ,-N-acetylhexosaminidase with a potential role in fertilization

DEVELOPMENT GROWTH & DIFFERENTIATION, Issue 3 2003
Ryo Koyanagi
,-N-Acetylhexosaminidase, which is found almost ubiquitously in sperm of invertebrates and vertebrates, supposedly mediates a carbohydrate-based transient sperm,egg coat binding. In ascidians and mammals, ,-hexosaminidase released at fertilization from eggs has been proposed to modify sperm receptor glycoproteins of the egg envelope, thus setting up a block to polyspermy. Previously, it was shown that in potential sperm receptor glycoproteins of the ascidian Phallusia mammillata, N-acetylglucosamine is the prevailing glycoside residue and that the egg harbors three active molecular forms of ,-hexosaminidase. In the present study, P. mammillata,-hexosaminidase cDNA was isolated from an ovarian cDNA library and characterized. The deduced amino acid sequence showed a high similarity with other known ,-hexosaminidases; however, P. mammillata,-hexosaminidase had a unique potential N-glycosylation site. A phylogenetic analysis suggested that P. mammillata,-hexosaminidase developed independently after having branched off from the common ancestor gene of the chordate enzyme before two isoforms of the mammalian enzyme appeared. In situ hybridization revealed stage-specific expression of ,-hexosaminidase mRNA during oogenesis in the oocyte and in the accessory test and follicle cells. This suggests that the three egg ,-hexosaminidase forms are specific for the oocyte, test cells and follicle cells. [source]

Nesprins, but not sun proteins, switch isoforms at the nuclear envelope during muscle development

DEVELOPMENTAL DYNAMICS, Issue 3 2010
K. Natalie Randles
Abstract Nesprins are a family of nuclear transmembrane proteins anchored via Sun proteins to the nuclear membrane. Analysis of nesprins during human muscle development revealed an increase in nesprin-1-giant during early myogenesis in vitro. During the transition from immature to mature muscle fibres in vivo, nesprin-2 partly replaced nesprin-1 at the nuclear envelope and short nesprin isoforms became dominant. Sun1 and Sun2 proteins remained unchanged during this fibre maturation. In emerin-negative skin fibroblasts, nesprin-2-giant was relocated from the nuclear envelope to the cytoplasm, not to the endoplasmic reticulum, while nesprin-1 remained at the nuclear envelope. In emerin-negative keratinocytes lacking nesprin-1, nesprin-2 remained at the nuclear envelope. HeLa cell nuclear envelopes lacked nesprin-1, which was the dominant form in myoblasts, while a novel 130-kD nesprin-2 isoform dominated Ntera-2 cells. The results suggest the possibility of isoform-specific and tissue-specific roles for nesprins in nuclear positioning. Developmental Dynamics 239:998,1009, 2010. © 2010 Wiley-Liss, Inc. [source]

Rnf19a, a ubiquitin protein ligase, and Psmc3, a component of the 26S proteasome, Tether to the acrosome membranes and the head,tail coupling apparatus during rat spermatid development

DEVELOPMENTAL DYNAMICS, Issue 7 2009
Eugene Rivkin
Abstract We report the cDNA cloning of rat testis Rnf19a, a ubiquitin protein ligase, and show 98% and 93% protein sequence identity of testicular mouse and human Rnf19a, respectively. Rnf19a interacts with Psmc3, a protein component of the 19S regulatory cap of the 26S proteasome. During spermatid development, Rnf19a and Psmc3 are initially found in Golgi-derived proacrosomal vesicles. Later on, Rnf19a, Psmc3, and ubiquitin are seen along the cytosolic side of the acrosomal membranes and the acroplaxome, a cytoskeletal plate linking the acrosome to the spermatid nuclear envelope. Rnf19a and Psmc3 accumulate at the acroplaxome marginal ring,manchette perinuclear ring region during spermatid head shaping and in the developing sperm head,tail coupling apparatus and tail. Rnf19a and Psmc3 may interact directly or indirectly with each other, presumably pointing to the participation of the ubiquitin,proteasome system in acrosome biogenesis, spermatid head shaping, and development of the head-tail coupling apparatus and tail. Developmental Dynamics 238:1851,1861, 2009. © 2009 Wiley-Liss, Inc. [source]

Seasonal changes in frequency tuning and temporal processing in single neurons in the frog auditory midbrain

DEVELOPMENTAL NEUROBIOLOGY, Issue 1 2005
Jozien BM Goense
Abstract Frogs rely on acoustic signaling to detect, discriminate, and localize mates. In the temperate zone, reproduction occurs in the spring, when frogs emerge from hibernation and engage in acoustically guided behaviors. In response to the species mating call, males typically show evoked vocal responses or other territorial behaviors, and females show phonotactic responses. Because of their strong seasonal behavior, it is possible that the frog auditory system also displays seasonal variation, as evidenced in their vocal control system. This hypothesis was tested in male Northern leopard frogs by evaluating the response characteristics of single neurons in the torus semicircularis (TS; a homolog of the inferior colliculus) to a synthetic mating call at different times of the year. We found that TS neurons displayed a seasonal change in frequency tuning and temporal properties. Frequency tuning shifted from a predominance of TS units sensitive to intermediate frequencies (700,1200 Hz) in the winter, to low frequencies (100,600 Hz) in the summer. In winter and early spring, most TS neurons showed poor, or weak, time locking to the envelope of the amplitude-modulated synthetic call, whereas in late spring and early summer the majority of TS neurons showed robust time-locked responses. These seasonal differences indicate that neural coding by auditory midbrain neurons in the Northern leopard frog is subject to seasonal fluctuation. © 2005 Wiley Periodicals, Inc. J. Neurobiol, 2005 [source]

Age-related changes in transient and oscillatory brain responses to auditory stimulation during early adolescence

DEVELOPMENTAL SCIENCE, Issue 2 2009
Catherine Poulsen
Maturational changes in the capacity to process quickly the temporal envelope of sound have been linked to language abilities in typically developing individuals. As part of a longitudinal study of brain maturation and cognitive development during adolescence, we employed dense-array EEG and spatiotemporal source analysis to characterize maturational changes in the timing of brain responses to temporal variations in sound. We found significant changes in the brain responses compared longitudinally at two time points in early adolescence, namely 10 years (65 subjects) and 11.5 years (60 of the 65 subjects), as well as large differences between adults, studied with the same protocol (Poulsen, Picton & Paus, 2007), and the children at 10 and 11.5 years of age. The transient auditory evoked potential to tone onset showed decreases in the latency of vertex and T-complex components, and a highly significant increase in the amplitude of the N1 wave with increasing age. The auditory steady state response to a 40-Hz frequency-modulated tone increased in amplitude with increasing age. The peak frequency of the envelope-following response to sweeps of amplitude-modulated white noise also increased significantly with increasing age. These results indicate persistent maturation of the cortical mechanisms for auditory processing from childhood into middle adulthood. [source]

Degeneration of germ line cells in amphibian ovary

ACTA ZOOLOGICA, Issue 3 2010
Maria Ogielska
Abstract Ogielska, M., Rozenblut, B., Augusty,ska, R., Kotusz, A. 2010. Degeneration of germ line cells in amphibian ovary. ,Acta Zoologica (Stockholm) 91: 319,327 We studied the morphology of degenerating ovarian follicles in juvenile and adult frogs Rana temporaria, Rana lessonae and Rana ridibunda. Degeneration of primordial germ cells was never observed and was extremely rare in oogonia and early oocytes in a cyst phase in juveniles. Previtellogenic oocytes were rarely affected. Three main types of atresia were identified. In type I (subdivided into stages A,D), vitellogenic oocytes are digested by proliferating follicle cells that hypertrophy and become phagocytic. A , germinal vesicle shrinks, nucleoli fuse, oocyte envelope interrupts, and follicular cells hypertrophy; B , follicular cells multiply and invade the oocyte; C , entire vesicle is filled by phagocytic cells; D , degenerating phagocytes accumulate black pigment. Type II is rare and resembles breakdown of follicles and release of ooplasm. In type III, observed in previtellogenic and early vitellogenic oocytes, ooplasm and germinal vesicle shrink, follicle cells do not invade the vesicle, and condensed ooplasm becomes fragmented. The residual oogonia in adult ovaries (germ patches) multiply, but soon degenerate. [source]

Predicting the impact of climate change on Australia's most endangered snake, Hoplocephalus bungaroides

DIVERSITY AND DISTRIBUTIONS, Issue 1 2010
Trent D. Penman
Abstract Aim, To predict how the bioclimatic envelope of the broad-headed snake (BHS) (Hoplocephalus bungaroides) may be redistributed under future climate warming scenarios. Location, South-eastern New South Wales, Australia. Methods, We used 159 independent locations for the species and 35 climatic variables to model the bioclimatic envelope for the BHS using two modelling approaches , Bioclim and Maxent. Predictions were made under current climatic conditions and we also predicted the species distribution under low and high climate change scenarios for 2030 and 2070. Results, Broad-headed snakes currently encompass their entire bioclimatic envelope. Both modelling approaches predict that suitable climate space for BHS will be lost to varying degrees under both climate warming scenarios, and under the worst case, only 14% of known snake populations may persist. Main conclusions, Areas of higher elevation within the current range will be most important for persistence of this species because they will remain relatively moist and cool even under climate change and will match the current climate envelope. Conservation efforts should focus on areas where suitable climate space may persist under climate warming scenarios. Long-term monitoring programs should be established both in these areas and where populations are predicted to become extirpated, so that we can accurately determine changes in the distribution of this species throughout its range. [source]

From introduction to the establishment of alien species: bioclimatic differences between presence and reproduction localities in the slider turtle

DIVERSITY AND DISTRIBUTIONS, Issue 1 2009
Gentile Francesco Ficetola
ABSTRACT Aim, Understanding the factors determining the transition from introduction of aliens to the establishment of invasive populations is a critical issue of the study of biological invasions, and has key implications for management. Differences in fitness among areas of introduction can define the zones where aliens become invasive. The American slider turtle Trachemys scripta has been introduced worldwide, and has negative effects on freshwater communities, but only a subset of introduced populations breed successfully. We used species distribution models to assess the factors influencing the slider distribution in Italy, by analysing bioclimatic features that can cause the transition from presence of feral adults to breeding populations. We also evaluated whether climate change might increase the future suitability for reproduction. Location,, Central and Northern Italy. Methods,, The distribution of slider turtle was obtained from the literature, unpublished reports and field surveys. We used Maxent to build bioclimatic models. Results,, Reproductive populations are associated to a clear bioclimatic envelope with warmer climate, more solar radiation and higher precipitations than populations where reproduction is not observed. Several Mediterranean areas currently have climatic features suitable for sliders. Scenarios of climate change predict the expansion of these areas. In the near future (2020), the proportion of populations in areas suitable for reproduction will dramatically increase. Main conclusion,, Our study shows that bioclimatic differences can determine the areas where aliens become invaders. Management should be focused to these source areas. However, climate change can increase fitness in the future, and therefore the interactions between climate change and fitness can boost the invasiveness of this alien species. [source]

The impact of prolonged fasting during aestivation on the structure of the small intestine in the green-striped burrowing frog, Cyclorana alboguttata

ACTA ZOOLOGICA, Issue 1 2005
Rebecca L. Cramp
Abstract The effects of short-term fasting and prolonged fasting during aestivation on the morphology of the proximal small intestine and associated organs were investigated in the green-striped burrowing frog, Cyclorana alboguttata (Anura: Hylidae). Animals were fasted for 1 week while active or for 3,9 months during aestivation. Short-duration fasting (1 week) had little effect on the morphology of the small intestine, whilst prolonged fasting during aestivation induced marked enteropathy including reductions in intestinal mass, length and diameter, longitudinal fold height and tunica muscularis thickness. Enterocyte morphology was also affected markedly by prolonged fasting: enterocyte cross-sectional area and microvillous height were reduced during aestivation, intercellular spaces were visibly reduced and the prevalence of lymphocytes amongst enterocytes was increased. Mitochondria and nuclei were also affected by 9 months of aestivation with major disruptions to mitochondrial cristae and increased clumping of nuclear material and increased infolding of the nuclear envelope. The present study demonstrates that the intestine of an aestivating frog responds to prolonged food deprivation during aestivation by reducing in size, presumably to reduce the energy expenditure of the organ. [source]

Fine structure of unusual spermatozoa and spermiogenesis of the mite Megisthanus floridanus Banks, 1904 (Acari: Gamasida: Antennophorina)

ACTA ZOOLOGICA, Issue 4 2002
Gerd Alberti
Abstract The aflagellate spermatozoa of the gamasid mite Megisthanus floridanus are characterized by a large vacuole which contains a cytoplasmic column protruding into the vacuole from the region defined as the posterior part of the cell. The membrane of the column and the inner membrane of the posterior part of the cytoplasmic mantle (outer sheath) surrounding the vacuole bear numerous so-called cellular processes. However, most of the outer sheath is reduced and represented solely by a very thin membrane-like envelope. The posterior part of the cell bears extensive folds. The cell, or, more precisely, the column, shows a deep posterior invagination. This invagination contains extracellular material composed of thin filaments or strands. Peripheral folds emerging from the posterior rim of the cell form a thin-walled tube that contains the same material as the invagination. The elongated nucleus is attached to a peculiar acrosomal complex consisting of a flat acrosomal cisterna that parallels most of the cell membrane, an attachment cone, and a short acrosomal filament which is embedded in a narrow canal within the nucleus. The spermatozoa of M. floridanus represent a peculiar version of the vacuolated type of sperm known to be plesiomorphic within the anactinotrichid Acari. Some details of spermiogenesis are described and consequences for phylogenetic and systematic considerations are discussed. [source]

Process,form relationships in Southern Italian badlands: erosion rates and implications for landform evolution

EARTH SURFACE PROCESSES AND LANDFORMS, Issue 1 2006
Michèle L. Clarke
Abstract Characteristic badlands are incised into Plio-Pleistocene clays in Basilicata, southern Italy, creating steep, scarp slopes with knife-edge ridges (calanchi) and small dome-shaped forms (biancane). Erosion pin data for the period 1997,2003 give mean annual erosion rates for dome-shaped biancane in the range 9,19 mm a,1, while rates for the calanchi scarps are lower, at 7,10 mm a,1. The erosion pin data also show a non-linear relationship with slope angle. Maximum erosion rates coincide with a slope angle of 35°, within an envelope defined by combining the theoretical effects of both rainsplash and surface weathering. Monitoring of surface changes and erosion rates for two 0·5 m2 cleared swathes on biancane forms reveals a complex relationship between weathering and erosion. Characteristic forms can develop from large blocks of intact clay bedrock over a time period of less than 30 a. The implications of the measured erosion rates for the landform association of mountain front/pediment/domed inselberg are explored. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Synthesis and function of the fibrous layers covering the eggs of Siphlonurus lacustris (Ephemeroptera, Siphlonuridae)

ACTA ZOOLOGICA, Issue 1 2001
Elda Gaino
Abstract Ultrastructural analysis (transmission and electron scanning microscopy) of the eggs of the mayfly Siphlonurus lacustris (Eaton) showed that they are wrapped in a thick coat composed of a network of tightly entwined filaments. Groups of twisted filaments form slightly uplifted buttons that are scattered on the coat surface. After experimentally induced egg deposition, egg,water interaction promotes marked cohesion of the eggs and their firm adhesion to the substrate. Egg masses include numerous gametes; the covering of those located close to the substrate greatly extends to anchor the whole mass. Eggs removed from the coat reveal a slightly punctuated smooth chorion and tagenoform micropyles (three to five). The coat increases egg size by about 20%. The lack of female reproductive accessory glands in Ephemeroptera transfers the synthesis of the adhesive coats to the follicle cells, which are typically competent for insect egg shell deposition (vitelline envelope and chorionic layers). This covering results from electron-dense granules that give rise to filaments progressively organized to form superimposed layers variously orientated around the egg. In addition to egg adhesion to the substrate, a trophic function and protection from shear stress are postulated for this covering. [source]

Quantized Double-Layer Charging of Iron Oxide Nanoparticles on a-Si:H Controlled by Charged Defects in a-Si:H

ELECTROANALYSIS, Issue 12 2007
Martin Weis
Abstract Sequential single-electron charging of iron oxide nanoparticles encapsulated in oleic acid/oleyl amine envelope and deposited by the Langmuir-Blodgett technique onto Pt electrode covered with undoped hydrogenated amorphous silicon film (a-Si:H) is reported. Quantized double-layer charging of nanoparticles is detected by cyclic voltammetry as current peaks and the charging effect can be switched on/off by the excess of negative/positive charged defect states in the a-Si:H layer. The particular charge states in a-Si:H are created by the simultaneous application of a suitable bias voltage and illumination before the measurement. [source]

Neonatal seizure detection using multichannel display of envelope trend

EPILEPSIA, Issue 2 2008
Nicholas S. Abend
Summary We aimed to determine whether analysis of EEG envelope trend aids bedside detection of neonatal seizures. Five neonatal EEGs with multiple seizures were used to determine optimal trend parameters for seizure detection. Using these parameters, envelope trends were generated on eight additional EEGs, evaluated by experienced and inexperienced users, and compared to traditional EEG interpretation. Seizures were best detected using envelope trend of 2,6 Hz activity over 20-s epochs. Experienced and inexperienced users identified 88% and 55% of prolonged seizures, respectively, 40% and 6% of brief seizures, and 20% and 0% of slowly evolving seizures. All users identified less than two false positives per hour. Thus, an experienced envelope trend user accurately identified longer seizures but did not identify brief or slowly evolving seizures. Less experienced users were less accurate. Trending may be a useful tool for seizure detection in some neonates. [source]

Conformational Flexibility in a Carbobicyclic Diphosphinite Ligand

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 20 2007
Ian J. S. Fairlamb
Abstract An unsymmetrical bicyclo[3.2.0]heptanyl diphosphinite ligand, FLEXIphosO, shows flexible coordination modes to palladium centres. The X-ray crystal structure for [Pd02(P,P,)3] has been determined which reveals that the bicyclic backbone of the FLEXIphosO ligand exists in an exo -envelope conformation. The change in conformation stands in stark contrast to that observed in mononuclear neutral and cationic palladium(II) complexes containing the FLEXIphosO ligand, where an endo -envelope is observed in solution and in the solid-state. Theoretical studies provide an insight into the relative stability of palladium(0) complexes containing the FLEXIphosO ligand. Another large spanning angle ligand, SPANphos, does not form a similar palladium(0) dimer complex under identical reaction conditions, highlighting the unusual behaviour of the FLEXIphosO ligand.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source]

Neural responses to uninterrupted natural speech can be extracted with precise temporal resolution

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 1 2010
Edmund C. Lalor
Abstract The human auditory system has evolved to efficiently process individual streams of speech. However, obtaining temporally detailed responses to distinct continuous natural speech streams has hitherto been impracticable using standard neurophysiological techniques. Here a method is described which provides for the estimation of a temporally precise electrophysiological response to uninterrupted natural speech. We have termed this response AESPA (Auditory Evoked Spread Spectrum Analysis) and it represents an estimate of the impulse response of the auditory system. It is obtained by assuming that the recorded electrophysiological function represents a convolution of the amplitude envelope of a continuous speech stream with the to-be-estimated impulse response. We present examples of these responses using both scalp and intracranially recorded human EEG, which were obtained while subjects listened to a binaurally presented recording of a male speaker reading naturally from a classic work of fiction. This method expands the arsenal of stimulation types that can now be effectively used to derive auditory evoked responses and allows for the use of considerably more ecologically valid stimulation parameters. Some implications for future research efforts are presented. [source]

Odorant specificity of three oscillations and the DC signal in the turtle olfactory bulb

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 3 2003
Ying-Wan Lam
Abstract The odour-induced population response in the in vivo turtle (Terepene sp.) olfactory bulb consists of three oscillatory components (rostral, middle and caudal) that ride on top of a DC signal. In an initial step to determine the functional role of these four signals, we compared the signals elicited by different odorants. Most experiments compared isoamyl acetate and cineole, odorants which have very different maps of input to olfactory bulb glomeruli in the turtle and a different perceptual quality for humans. We found substantial differences in the response to the two odours in the rise-time of the DC signal and in the latency of the middle oscillation. The rate of rise for cineole was twice as fast as that for isoamyl acetate. Similarly, the latency for the middle oscillation was about twice as long for isoamyl acetate as it was for cineole. On the other hand, a number of characteristics of the signals were not substantially different for the two odorants. These included the latency of the rostral and caudal oscillation, the frequency and envelope of all three oscillations and their locations and spatial extents. A smaller number of experiments were carried out with hexanone and hexanal; the oscillations elicited by these odorants did not appear to be different from those elicited by isoamyl acetate and cineole. Qualitative differences between the oscillations in the turtle and those in two invertebrate phyla suggest that different odour processing strategies may be used. [source]

Major components of a sea urchin block to polyspermy are structurally and functionally conserved

EVOLUTION AND DEVELOPMENT, Issue 3 2004
Julian L. Wong
Summary One sperm fusing with one egg is requisite for successful fertilization; additional sperm fusions are lethal to the embryo. Because sperm usually outnumber eggs, evolution has selected for mechanisms that prevent this polyspermy by immediately modifying the egg extracellular matrix. We focus here on the contribution of cortical granule contents in the sea urchin block to polyspermy to begin to understand how well this process is conserved. We identified each of the major constituents of the fertilization envelope in two species of seaurchins, Strongylocentrotus purpuratus and Lytechinus variegatus, that diverged 30 to 50 million years ago. Our results show that the five major structural components of the fertilization envelope, derived from the egg cortical granules, are semiconserved. Most of these orthologs share sequence identity and encode multiple low-density lipoprotein receptor type A repeats or CUB domains but at least two contain radically different carboxy-terminal repeats. Using a new association assay, we also show that these major structural components are functionally conserved during fertilization envelope construction. Thus, it seems that this population of female reproductive proteins has retained functional motifs while gaining significant sequence diversity,two opposing paths that may reflect cooperativity among the proteins that compose the fertilization envelope. [source]

Incorporation of ZP1 into perivitelline membrane after in vivo treatment with exogenous ZP1 in Japanese quail (Coturnix japonica)

FEBS JOURNAL, Issue 14 2008
Mihoko Kinoshita
In birds, the egg envelope surrounding the oocyte prior to ovulation is called the perivitelline membrane and it plays important roles in fertilization. In a previous study we demonstrated that one of the components of the perivitelline membrane, ZP3, which is secreted from the ovarian granulosa cells, specifically interacts with ZP1, another constituent that is synthesized in the liver of Japanese quail. In the present study, we investigated whether ZP1 injected exogenously into the blood possesses the ability to reconstruct the perivitelline membrane of Japanese quail. When ZP1 purified from the serum of laying quail was injected into other female birds, the signal of this exogenous ZP1 was detected in the perivitelline membrane. In addition, we revealed, by means of ligand blot analysis, that serum ZP1 interacts with both ZP1 and ZP3 of the perivitelline membrane. By contrast, when ZP1 derived from the perivitelline membrane was administered, it failed to become incorporated into the perivitelline membrane. Interestingly, serum ZP1 recovered from other Galliformes, including chicken and guinea fowl, could be incorporated into the quail perivitelline membrane, but the degree of interaction between quail ZP3 and ZP1 of the vitelline membrane of laid eggs from chicken and guinea fowl appeared to be weak. These results demonstrate that exogenous ZP1 purified from the serum, but not ZP1 from the perivitelline membrane, can become incorporated into the perivitelline membrane upon injection into other types of female birds. To our knowledge, this is the first demonstration that the egg envelope component, when exogenously administered to animals, can reconstruct the egg envelope in vivo. [source]

Post-translational cleavage of recombinantly expressed nitrilase from Rhodococcus rhodochrous J1 yields a stable, active helical form

FEBS JOURNAL, Issue 8 2007
R. Ndoria Thuku
Nitrilases convert nitriles to the corresponding carboxylic acids and ammonia. The nitrilase from Rhodococcus rhodochrous J1 is known to be inactive as a dimer but to become active on oligomerization. The recombinant enzyme undergoes post-translational cleavage at approximately residue 327, resulting in the formation of active, helical homo-oligomers. Determining the 3D structure of these helices using electron microscopy, followed by fitting the stain envelope with a model based on homology with other members of the nitrilase superfamily, enables the interacting surfaces to be identified. This also suggests that the reason for formation of the helices is related to the removal of steric hindrance arising from the 39 C-terminal amino acids from the wild-type protein. The helical form can be generated by expressing only residues 1,327. [source]