bluuebunny/crossref_metadata_2025_split huggingface dataset:
Activation of muscarinic cholinergic receptors inhibits giant neurones in the caudal pontine reticular nucleus
Authors: Bosch Daniel , Schmid Susanne 
Published: October 2006

AbstractGiant neurones in the caudal pontine reticular nucleus (PnC) play a crucial role in mediating the mammalian startle response. They receive input from cochlear, trigeminal and vestibular nuclei and project directly to motoneurones. Furthermore, they integrate modulatory input from different brain regions either enhancing or inhibiting startle responses. One prominent startle modulation is prepulse inhibition where a non‐startling stimulus presented prior to the startle stimulus inhibits a subsequent startle response. Several behavioural studies have indicated that this inhibition is mediated by muscarinic receptors at the level of the PnC. Here, we performed whole‐cell patch‐clamp recordings from PnC giant neurones in acute rat brain slices in order to examine muscarinic inhibition. We stimulated afferent trigeminal and auditory fibres and applied muscarinic agonists and antagonists in order to investigate their effect on excitatory postsynaptic current amplitudes, paired‐pulse ratio and passive membrane properties of PnC giant neurones. The cholinergic agonist carbachol and the muscarinic agonist oxotremorine significantly reduced excitatory postsynaptic current amplitudes and increased the paired‐pulse ratio. Carbachol additionally reduced the membrane resistance of postsynaptic PnC giant neurones. The subtype‐specific antagonists AF‐DX116 (M2 preferring) and tropicamide (M4 preferring) antagonized the oxotremorine effect indicating that M4 and possibly M2 receptor subtypes are involved in this inhibition. The G‐protein‐activated inward rectifying potassium channel blocker tertiapin‐Q had no effect on oxotremorine‐induced inhibition of giant neurones. Our results show a mainly presynaptically mediated strong inhibition of PnC giant neurones by activation of M4 and possibly M2 receptors that presumably contribute to prepulse inhibition.
Neuropathic pain and the endocannabinoid system in the dorsal raphe: pharmacological treatment and interactions with the serotonergic system
Authors: Palazzo Enza , De Novellis Vito , Petrosino Stefania , Marabese Ida , Vita Daniela , Giordano Catia , Di Marzo Vincenzo , Mangoni Giuseppe Salvatore , Rossi Francesco , Maione Sabatino 
Published: October 2006

AbstractWe used a model of neuropathic pain consisting of rats with chronic constriction injury (CCI) of the sciatic nerve, in order to investigate whether endocannabinoid levels are altered in the dorsal raphe (DR) and to assess the effect of repeated treatment with (R)‐(+)‐[2,3‐dihydro‐5‐methyl‐3‐(4‐morpholinylmethyl)pyrrolo[1,2,3‐de]‐1,4‐benzoxazin‐6‐yl]‐1‐naphthalenylmethanone mesylate, a synthetic cannabinoid agonist, or N‐(4‐hydroxyphenyl)‐5Z,8Z,11Z,14Z‐eicosatetraenamide (AM404), an inhibitor of endocannabinoid reuptake, on DR serotonergic neuronal activity and on behavioural hyperalgesia. CCI resulted in significantly elevated anandamide but not 2‐arachidonoylglycerol levels in the DR. Furthermore, as well as thermal and mechanical hyperalgesia, CCI caused serotonergic hyperactivity (as shown by the increase of basal activity of serotonergic neurones, extracellular serotonin levels and expression of 5‐HT1Areceptor gene). Repeated treatment with either (R)‐(+)‐[2,3‐dihydro‐5‐methyl‐3‐(4‐morpholinylmethyl)pyrrolo[1,2,3‐de]‐1,4‐benzoxazin‐6‐yl]‐1‐naphthalenylmethanone mesylate or AM404 reverted the hyperalgesia and enhanced serotonergic activity induced by CCI in a way attenuated by N‐piperidino‐5‐(4‐chlorophenyl)‐1‐(2,4dichlorophenyl)‐4‐methyl‐3‐pyrazolecarboxamide, a selective cannabinoid subtype 1 (CB1) receptor antagonist. Despite the elevated levels of anandamide following CCI, N‐piperidino‐5‐(4‐chlorophenyl)‐1‐(2,4dichlorophenyl)‐4‐methyl‐3‐pyrazolecarboxamide did not produce hyperalgesia or any other effect on serotonergic neuronal activity when administered alone. Furthermore, the effects of AM404 were not accompanied by an increase in endocannabinoid levels in the DR. In conclusion, following CCI of the sciatic nerve, the endocannabinoid and serotonergic systems are activated in the DR, where repeated stimulation of CB1receptors with exogenous compounds restores DR serotonergic activity, as well as thermal and mechanical nociceptive thresholds, to pre‐surgery levels. However, an elevated level of endogenous anandamide in the DR does not necessarily contribute to the CB1‐mediated tonic control of analgesia and serotonergic neuronal activity.
Diversity of the cadmium‐containing carbonic anhydrase in marine diatoms and natural waters
Authors: Park Haewon , Song Bongkeun , Morel François M. M. 
Published: October 2006

SummaryA recent report of a novel carbonic anhydrase (CDCA1) with Cd as its metal centre in the coastal diatom Thalassiosira weissflogii has led us to search for the occurrence of this Cd enzyme (CDCA) in other marine phytoplankton and in the environment. Using degenerate primers designed from the published sequences from T. weissflogii and a putative sequence in the genome of Thalassiosira pseudonana, we show that CDCA is widespread in diatom species and ubiquitous in the environment. All detected genes share more than 64% amino acid identity with the CDCA of T. pseudonana. Analysis of the amino acid sequence of CDCA shows that the putative Cd binding site resembles that of beta‐class carbonic anhydrases (CAs). The prevalence of CAs in diatoms that presumably contain Cd at their active site probably reflects the very low concentration of Zn in the marine environment and the difficulty in acquiring inorganic carbon for photosynthesis. The cdca primers developed in this study should be useful for detecting cdca genes in the field, and studying the conditions under which they are expressed.
A Situated Knowledge Representation of Geographical Information
Authors: Gahegan Mark , Pike William 
Published: October 2006

AbstractIn this paper we present an approach to conceiving of, constructing and comparing the concepts developed and used by geographers, environmental scientists and other earth science researchers to help describe, analyze and ultimately understand their subject of study. Our approach is informed by the situations under which concepts are conceived and applied, captures details of their construction, use and evolution and supports their ultimate sharing along with the means for deep exploration of conceptual similarities and differences that may arise among a distributed network of researchers. The intent here is to support different perspectives onto GIS resources that researchers may legitimately take, and to capture and compute with aspects of epistemology, to complement the ontologies that are currently receiving much attention in the GIScience community.
Trade and Diversity: Is There a Case for ‘Cultural Protectionism?’
Authors: Eckel Carsten 
Published: October 2006

Abstract
In contrast to the predictions of standard models of international trade, globalization critics are claiming that trade destroys diversity. We demonstrate that with endogenous sunk costs, trade integration in horizontally differentiated industries can indeed lead to a fall in diversity. Consumers are faced with a tradeoff between gains in real income and a loss in diversity, so that the impact on welfare is ambiguous. However, it is possible through fiscal policies to replicate pre-trade choices and still realize gains in real income. Thus, calls for a ‘cultural protectionism’ are not justified.
Interrelationship and Familiality of Dyslexia Related Quantitative Measures
Authors: Schulte‐Körne G. , Ziegler A. , Deimel W. , Schumacher J. , Plume E. , Bachmann C. , Kleensang A. , Propping P. , Nöthen M. M. , Warnke A. , Remschmidt H. , König I. R. 
Published: October 2006

SummaryDyslexia is a complex gene‐environment disorder with poorly understood etiology that affects about 5% of school‐age children. Dyslexia occurs in all languages and is associated with a high level of social and psychological morbidity for the individual and their family; approximately 40‐50% have persistent disability into adulthood. The core symptoms are word reading and spelling deficits, but several other cognitive components influence the core phenotype.A broad spectrum of dyslexia related phenotypes, including phonological decoding, phoneme awareness, orthographic processing, short‐term memory, rapid naming and basic mathematical abilities, were investigated in large sample of 287 German dyslexia families. We explored the interrelationship between the component phenotypes using correlation and principal component analyses (PCA). In addition, we estimated familiality for phenotypes as well as for the factors suggested by PCA.The correlation between the component phenotypes varied between −0.1 and 0.7. The PCA resulted in three factors: a general dyslexia factor, a speed of processing factor and a mathematical abilities factor. The familiality estimates of single components and factors ranged between 0.25 and 0.63.Instead of analyzing single dyslexia‐related components, multivariate analyses including factor analytic approaches may help in the identification of susceptibility genes.
The structure of the cushions in the feet of African elephants (Loxodonta africana)
Authors: Weissengruber G. E. , Egger G. F. , Hutchinson J. R. , Groenewald H. B. , Elsässer L. , Famini D. , Forstenpointner G. 
Published: October 2006

AbstractThe uniquely designed limbs of the African elephant,Loxodonta africana, support the weight of the largest terrestrial animal. Besides other morphological peculiarities, the feet are equipped with large subcutaneous cushions which play an important role in distributing forces during weight bearing and in storing or absorbing mechanical forces. Although the cushions have been discussed in the literature and captive elephants, in particular, are frequently affected by foot disorders, precise morphological data are sparse. The cushions in the feet of African elephants were examined by means of standard anatomical and histological techniques, computed tomography (CT) and magnetic resonance imaging (MRI). In both the forelimb and the hindlimb a 6th ray, the prepollex or prehallux, is present. These cartilaginous rods support the metacarpal or metatarsal compartment of the cushions. None of the rays touches the ground directly. The cushions consist of sheets or strands of fibrous connective tissue forming larger metacarpal/metatarsal and digital compartments and smaller chambers which were filled with adipose tissue. The compartments are situated between tarsal, metatarsal, metacarpal bones, proximal phalanges or other structures of the locomotor apparatus covering the bones palmarly/plantarly and the thick sole skin. Within the cushions, collagen, reticulin and elastic fibres are found. In the main parts, vascular supply is good and numerous nerves course within the entire cushion. Vater–Pacinian corpuscles are embedded within the collagenous tissue of the cushions and within the dermis. Meissner corpuscles are found in the dermal papillae of the foot skin. The micromorphology of elephant feet cushions resembles that of digital cushions in cattle or of the foot pads in humans but not that of digital cushions in horses. Besides their important mechanical properties, foot cushions in elephants seem to be very sensitive structures.
HARMONIZING REGULATIONS FOR BIOMEDICAL RESEARCH: A CRITICAL ANALYSIS OF THE US AND VENEZUELAN SYSTEMS
Authors: DI TILLIO‐GONZALEZ DANNIE , FISCHBACH RUTH L. 
Published: October 2006

ABSTRACTThis article aims to compare the national legal systems that regulate biomedical research in an industrialized country (United States) and a developing country (Venezuela). A new international order is emerging in which Europe, Japan and the United States (US) are revising common guidelines and harmonizing standards. In this article, we analyze – as an example – the US system. This system is controlled by a federal agency structured to regulate research funded by the federal government uniformly, either in the US or abroad. In contrast, in Venezuela, a developing country, the creation of a centralized system is a slow process. Different types of ethical committees review research projects using non‐uniform criteria. Consequently, various parallel organizations that conduct biomedical research, such as universities, research institutes and private hospitals have diverse regulations operating at a local level. Thus, the most relevant difference between the Venezuelan and the US systems is the degree of standardization. In the US, the review process is performed by institutional review boards (IRBs), which have a similar organization and maintain relationships with a centralized agency, following standard regulations. Although new proposals for establishing national regulations are currently being considered in Venezuela, the success of these initiatives will depend on promoting governmental efforts to create a more structured centralized system supported by a national regulatory framework. This system will need governmental financial support at all levels. This article proposes an integrated system to regulate research with human participants in Venezuela and other developing countries.
Dynamics in longitudinal eye movements and corneal shape
Authors: Robert Iskander D. , Kasprzak Henryk T. 
Published: October 2006

AbstractThe magnitude and character of longitudinal movements of the eye were studied in the context of high speed videokeratoscopy. It was of interest to determine whether these dynamic changes in the eye movements can affect the corneal shape and its estimation. A high speed videokeratoscope with a sampling frequency of 50 Hz was used for measuring the corneal apex movements as well as for measuring variations in the best‐fit sphere radius and central radius of curvature. The magnitude of the measured longitudinal apex movements could reach over 200 μm showing a slow trend. The estimated local changes of the apex movements that could be associated with the cardiopulmonary system were about 40–50 μm. The temporal variations in the equivalent estimated central radius of curvature ranged between 10 and 15 μm. Spectral analysis of the longitudinal eye movements revealed strong signatures of the pulse and respiration signals as well as the assumed blink control signal. No clear association between the longitudinal apex movements and the corneal curvature was found. However, very slow significant changes in the corneal shape were observed. The central radius of curvature of the cornea revealed slow changes of up to 120 μm. Understanding the nature of such changes will be of benefit in ophthalmic applications requiring highly accurate measurements of corneal shape, such as contact lens design and refractive surgery.
Approximating ocular surfaces by generalised conic curves
Authors: Kasprzak Henryk T. , Robert Iskander D. 
Published: October 2006

AbstractMost of the optical models of the human eye use simple conic functions to represent its individual components such as corneal surfaces and the surfaces of the crystalline lens. Although a conic function provides an acceptable approximation for most anatomical eye surfaces, it also leads to a simple optical analysis of the whole eye system. To fill the gap between the classical use of conic surfaces and the use of more sophisticated functions that often invoke numerically expensive procedures in the optical analysis, a functional generalisation of the conic curve is proposed. A detailed derivation of the generalised conic function is presented for a two‐dimensional (meridional) case. This is followed by a three‐dimensional surface approximation. Examples are given in which the superiority of the proposed approximation over a classical conic function as well as the hyperbolic cosine approximation is evident. In particular, it is shown that for an average total corneal profile, the proposed generalisation results in a residual height error that is of an order smaller than those achieved with the conic and hyperbolic cosine approximations. In conclusion, the proposed generalised conic function can be a useful tool in eye modelling, where the simplicity of expression is often desirable.
Immigrant Mental Health and Unemployment*
Authors: KENNEDY STEVEN , MCDONALD JAMES TED 
Published: October 2006

In this paper we examine how the stresses associated with the transition to a new country combined with additional stress arising from a period of unemployment affect the mental health of immigrants. Australian immigrants are found to have poorer mental health at 6 months after arrival in Australia compared with 18 and 42 months. Furthermore, unemployment, and especially a long duration of unemployment, is found to be associated with poor mental health. We found that although immigrant women appear unaffected by their spouses’ labour force status, there is evidence that immigrant men's mental health is affected by spouse labour force status.
The interaction between reaction and deformation: an experimental study using a biotite + plagioclase + quartz gneiss
Authors: HOLYOKE C. W. , TULLIS J. 
Published: October 2006

AbstractMetamorphic reactions commonly accompany ductile deformation of crustal rocks. We performed an experimental study to determine: (i) the effect of syn‐deformation reaction on strain weakening and localization, and (ii) the effect of crystal plastic deformation on reaction extent and distribution. Experiments were conducted on a fine‐grained gneiss (58 vol.% quartz, forming the interconnected matrix, 13 vol.% biotite, 28 vol.% plagioclase and 1 vol.% garnet/Fe‐Ti oxides). General shear experiments were performed at 745 and 800 °C, 1.5 GPa, two strain rates, and shear strain (γ) from 0.6 to 5, yielding three suites with initial phase strength contrast between the matrix quartz and weak biotite of 45×, 25× and 10×; hydrostatic experiments were performed on cores and powders at 750 and 800 °C and 1.5–2 GPa for the same times. At these conditions, biotite reacts with plagioclase and quartz to form garnet, K‐feldspar and water (no melt was observed). Greater reaction extent was observed in deformed samples than in equivalent hydrostatic samples, because of the increased surface area and internal strain energy. In all of the deformed samples, reaction contributes to strain weakening, due principally to a switch to grain boundary sliding in the fine‐grained reaction products. The degree to which syn‐deformational reaction causes strain weakening and localization in this polyphase aggregate depends on the phase strength contrast and how it evolves. In samples with low‐phase strength contrast, strain and reaction are homogeneously distributed; however, in samples with high‐phase strength contrast, ductile strain and reaction interact positively to produce a narrow ductile shear zone. Similar concentration of reaction is observed in some natural ductile shear zones.
Variations in rates of nucleation and growth of biotite porphyroblasts
Authors: HIRSCH D. M. , CARLSON W. D. 
Published: October 2006

AbstractDifferences in rates of nucleation and diffusion‐limited growth for biotite porphyroblasts in adjacent centimetre‐scale layers of a garnet‐biotite schist from the Picuris Mountains of New Mexico are revealed by variations in crystal size and abundance between two layers with strong compositional similarity. Relationships between fabrics recorded by inclusion patterns in biotite and garnet porphyroblasts are interpreted to reflect garnet growth following biotite growth, without substantial alteration of the biotite sizes. Sizes and locations of biotite crystals, obtained via high‐resolution X‐ray computed tomography, document that of the two adjacent layers, one has a larger mean crystal volume (9.5 × 10−4v. 2.4 × 10−4 cm3), fewer biotite crystals per unit volume (232 v. 576 crystals cm−3), and a higher volume fraction of biotite (23%v. 14%). The two layers have similar mineral assemblages and mineral chemistry. Both layers show evidence for diffusional control of nucleation and growth. Pseudosection analysis suggests that the large‐biotite layer began to crystallize biotite at a temperature ∼67 °C greater than the small‐biotite layer. Diffusion rates differed between layers, because of their different temperature ranges of crystallization, but this effect can be quantified. The bulk compositional difference between the layers, manifested in different modal amounts of biotite, has an effect on the biotite sizes that is also quantifiable and insufficient to account for the difference in biotite size. After these other possible causes of variation in crystal sizes have been eliminated, variability in nucleation and diffusion rates remain as the dominant factors responsible for the difference in porphyroblastic textures. Numerical simulations suggest that relative to the small‐biotite layer, the large‐biotite layer experienced elevated diffusion rates because of the higher crystallization temperature, as well as increased nucleation rates in order to achieve the observed size and number density of crystals. The simulations can replicate the observed textures only by invoking unreasonably large values for the thermal dependence of nucleation rates (activation energies), strongly suggesting that the observed textural differences arise from variations between layers in the abundance and energetics of potential nucleation sites.
Catastrophe Modeling in the Classroom
Authors: Born Patricia , Martin William 
Published: October 2006

AbstractCatastrophes are by definition rare, which makes it difficult to project future losses using historical loss information. Catastrophe modelers have developed alternative methodologies based on sophisticated techniques that combine physics, meteorology, engineering, statistics, actuarial sciences, and other disciplines to provide estimates of the likelihood of losses from extreme events. This article discusses the basics of catastrophe modeling and describes an approach to implementing a lesson on catastrophe modeling in the insurance curriculum.
Magnitude of Error Introduced by Application of Heart Rate Correction Formulas to the Canine QT Interval
Authors: King Andrew , Bailie Marc , Olivier N. Bari 
Published: October 2006

Background: Accurate detection of drug‐induced QT interval changes is often confounded by concurrent heart rate changes. Application of heart rate correction formulas has been the traditional approach to account for heart rate–induced QT interval changes, and thereby identify the direct effect of the test article on cardiac repolarization. Despite numerous recent studies identifying the imprecision of these formulas they continue to be applied. Methods: Using a chronic atrioventricular dissociated His‐paced canine model, heart rate correction methods were evaluated for their ability to generate a corrected QT interval independent of original heart rate. Additionally, His bundle pacing at a heart rate of 60 beats/min allowed calculation of the magnitude of error introduced by application of heart rate correction formulas. Results: Of the fixed parameter heart rate correction formulas, only Van de Water was able to predict corrected QT values independent of the original heart rate. The magnitude of error discovered by application of heart rate correction formulas varied, but in many cases was very large. Bazett's formula was associated with a mean overcorrection of 67.9 ms; Fridericia's 28.7 ms. Van de Water was the best fixed parameter formula with a mean error of 10.8 ms. As expected, group and individual corrections derived from linear regression of the HR‐QT data offered improvement over the traditional formulas. Both were able to predict QTc values independent of the heart rate. However, errors of the magnitude of 10 and 6 ms, respectively, were still introduced. Conclusion: Van de Water and linear regression correction methods were superior to others in this study, but all methods generated QTc errors equal to or much greater than the magnitude of interest for drug safety evaluation.