bluuebunny/crossref_metadata_2025 huggingface dataset:
Decoupled Plant and Insect Diversity After the End-Cretaceous Extinction
Authors: Wilf Peter , Labandeira Conrad C. , Johnson Kirk R. , Ellis Beth
Published: August 2006

Food web recovery from mass extinction is poorly understood. We analyzed insect-feeding damage on 14,999 angiosperm leaves from 14 latest Cretaceous, Paleocene, and early Eocene sites in the western interior United States. Most Paleocene floras have low richness of plants and of insect damage. However, a low-diversity 64.4-million-year-old flora from southeastern Montana shows extremely high insect damage richness, especially of leaf mining, whereas an anomalously diverse 63.8-million-year-old flora from the Denver Basin shows little damage and virtually no specialized feeding. These findings reveal severely unbalanced food webs 1 to 2 million years after the end-Cretaceous extinction 65.5 million years ago.
Science Undermined by Our Limited Imagination?
Authors: Lewens Tim
Published: August 2006

Exceeding Our Grasp
. Science, History, and the Problem of Unconceived Alternatives.
By P. Kyle Stanford
. Oxford University Press, Oxford, 2006. 248 pp. $45. ISBN 0-19-517408-9.

The author uses a consideration of 19th-century theories of inheritance and generation to support his claim that scientists often fail to conceive of alternatives to their own theories, even when these alternatives are well supported by evidence available at the time and sufficiently strong to become accepted later.
For Our Thirsty World, Efficiency or Else
Authors: Postel Sandra L.
Published: August 2006

When the Rivers Run Dry
. Water--The Defining Crisis of the Twenty-First Century.
Fred Pearce
. Beacon Press, Boston, 2006. 336 pp. $26.95. ISBN 0-8070-8572-3.

Weaving together scientific, economic, and historical aspects of water resources, the author argues that the solution to the growing worldwide shortage of water lies in greater efficiency and new ethics of use.
“Goalkeeper’s hip”: acute haematogenous osteomyelitis secondary to apophyseal fractures
Authors: Dunsmuir R A , Barnes S J , McGarrity G
Published: August 2006

We report two cases of acute haematogenous osteomyelitis in the anterior superior iliac spine (ASIS) in adolescent goalkeepers following trauma of the iliac crest apophysis. Both patients complained of pain over their right ASIS and were pyrexial. They were given antibiotics and were discharged from follow up without complication 64 and 90 days after starting treatment.
Concussion history is not a predictor of computerised neurocognitive performance
Authors: Broglio S P , Ferrara M S , Piland S G , Anderson R B
Published: August 2006

Background:The long term effects of self reported concussion on neurocognitive functioning have been found to be variable.

Objectives:To evaluate cognitive performance on the Headminder concussion resolution index (CRI) and ImPACT assessment tests of subjects with and without a history of self reported concussion.

Methods:A retrospective analysis was completed on 235 Headminder CRI baseline assessments and 264 ImPACT baseline assessments. Participants were divided into four groups on the basis of reported number of concussions (zero, one, two, or three). Multivariate analysis of variance was used to evaluate differences between the concussion history groups on the two computer based concussion assessment programs.

Results:Multivariate analysis of variance indicated no significant difference between those with and without a history of concussion on the CRI (Λ  =  0.963,F(15, 627.05) =  0.57, p  =  0.898). It also revealed no significant differences between groups on the ImPACT test (Λ  =  0.951,F(12, 672.31) =  1.07, p  =  0.381).

Conclusions:The results suggest that either long term cognitive decrements may not be associated with a history of concussion or the decrements may be subtle and undetectable by these computer programs.
Ecological and Evolutionary Responses to Recent Climate Change
Authors: Parmesan Camille
Published: August 2006

Ecological changes in the phenology and distribution of plants and animals are occurring in all well-studied marine, freshwater, and terrestrial groups. These observed changes are heavily biased in the directions predicted from global warming and have been linked to local or regional climate change through correlations between climate and biological variation, field and laboratory experiments, and physiological research. Range-restricted species, particularly polar and mountaintop species, show severe range contractions and have been the first groups in which entire species have gone extinct due to recent climate change. Tropical coral reefs and amphibians have been most negatively affected. Predator-prey and plant-insect interactions have been disrupted when interacting species have responded differently to warming. Evolutionary adaptations to warmer conditions have occurred in the interiors of species' ranges, and resource use and dispersal have evolved rapidly at expanding range margins. Observed genetic shifts modulate local effects of climate change, but there is little evidence that they will mitigate negative effects at the species level.
aPKC-PAR complex dysfunction and tight junction disassembly in renal epithelial cells during ATP depletion
Authors: Gopalakrishnan Shobha , Hallett Mark A. , Atkinson Simon J. , Marrs James A.
Published: August 2006

Renal ischemia and in vitro ATP depletion result in disruption of the epithelial tight junction barrier, which is accompanied by breakdown of plasma membrane polarity. Tight junction formation is regulated by evolutionarily conserved complexes, including that of atypical protein kinase C (aPKC), Par3, and Par6. The aPKC signaling complex is activated by Rac and regulated by protein phosphorylation and associations with other tight junction regulatory proteins, for example, mLgl. In this study, we examined the role of aPKC signaling complex during ATP depletion and recovery in Madin-Darby canine kidney cells. ATP depletion reduced Rac GTPase activity and induced Par3, aPKCζ, and mLgl-1 redistribution from sites of cell-cell contact, which was restored following recovery from ATP depletion. Zonula occludens (ZO)-1 and Par3 phosphorylation was reduced and association of aPKCζ with its substrates Par3 and mLgl-1 was stabilized in ATP-depleted Madin-Darby canine kidney cells. ATP depletion also induced a stable association of Par3 with Tiam-1, a Rac GTPase exchange factor, which explains how aPKCζ and Rac activities were suppressed. Experimental inhibition of aPKCζ during recovery from ATP depletion interfered with reassembly of ZO-1 and Par3 at cell junctions. These data indicate that aPKC signaling is impaired during ATP depletion, participates in tight junction disassembly during cell injury and is important for tight junction reassembly during recovery.
Tissue heterogeneity of the mammalian mitochondrial proteome
Authors: Johnson D. Thor , Harris Robert A. , French Stephanie , Blair Paul V. , You Jinsam , Bemis Kerry G. , Wang Mu , Balaban Robert S.
Published: August 2006

The functionality of the mitochondrion is primarily determined by nuclear encoded proteins. The mitochondrial functional requirements of different tissues vary from a significant biosynthetic role (liver) to a primarily energy metabolism-oriented organelle (heart). The purpose of this study was to compare the mitochondrial proteome from four different tissues of the rat, brain, liver, heart, and kidney, to provide insight into the extent of mitochondrial heterogeneity and to further characterize the overall mitochondrial proteome. Mitochondria were isolated, solubilized, digested, and subjected to quantitative liquid chromatography-mass spectroscopy. Of the 16,950 distinct peptides detected, 8,045 proteins were identified. High-confidence identification threshold was reached by 1,162 peptides, which were further analyzed. Of these 1,162 proteins, 1,149 were significantly different in content ( P and q values < 0.05) between at least 2 tissues, whereas 13 were not significantly different between any tissues. Confirmation of the mitochondrial origin of proteins was determined from the literature or via NH2-terminal mitochondrial localization signals. With these criteria, 382 proteins in the significantly different groups were confirmed to be mitochondrial, and 493 could not be confirmed to be mitochondrial but were not definitively localized elsewhere in the cell. A total of 145 proteins were assigned to the rat mitochondrial proteome for the first time via their NH2-terminal mitochondrial localization signals. Among the proteins that were not significantly different between tissues, three were confirmed to be mitochondrial. Most notable of the significantly different proteins were histone family proteins and several structural proteins, including tubulin and intermediate filaments. The mitochondrial proteome from each tissue had very specific characteristics indicative of different functional emphasis. These data confirm the notion that mitochondria are tuned by the nucleus for specific functions in different tissues.
Chondrocyte intracellular calcium, cytoskeletal organization, and gene expression responses to dynamic osmotic loading
Authors: Chao Pen-hsiu Grace , West Alan C. , Hung Clark T.
Published: August 2006

While chondrocytes in articular cartilage experience dynamic stimuli from joint loading activities, few studies have examined the effects of dynamic osmotic loading on their signaling and biosynthetic activities. We hypothesize that dynamic osmotic loading modulates chondrocyte signaling and gene expression differently than static osmotic loading. With the use of a novel microfluidic device developed in our laboratory, dynamic hypotonic loading (−200 mosM) was applied up to 0.1 Hz and chondrocyte calcium signaling, cytoskeleton organization, and gene expression responses were examined. Chondrocytes exhibited decreasing volume and calcium responses with increasing loading frequency. Phalloidin staining showed osmotic loading-induced changes to the actin cytoskeleton in chondrocytes. Real-time PCR analysis revealed a stimulatory effect of dynamic osmotic loading compared with static osmotic loading. These studies illustrate the utility of the microfluidic device in cell signaling investigations, and their potential role in helping to elucidate mechanisms that mediate chondrocyte mechanotransduction to dynamic stimuli.
CO2 chemosensitivity in Helix aspersa: three potassium currents mediate pH-sensitive neuronal spike timing
Authors: Denton Jerod S. , McCann F. V. , Leiter J. C.
Published: August 2006

Elevated levels of carbon dioxide increase lung ventilation in Helix aspersa. The hypercapnic response originates from a discrete respiratory chemosensory region in the dorsal subesophageal ganglia that contains CO2-sensitive neurons. We tested the hypothesis that pH-dependent inhibition of potassium channels in neurons in this region mediated the chemosensory response to CO2. Cells isolated from the dorsal subesophageal ganglia retained CO2 chemosensitivity and exhibited membrane depolarization and/or an increase in input resistance during an acid challenge. Isolated somata expressed two voltage-dependent potassium channels, an A-type and a delayed-rectifier-type channel ( IKA and IKDR). Both conductances were inhibited during hypercapnia. The pattern of voltage dependence indicated that IKA was affected by extracellular or intracellular pH, but the activity of IKDR was modulated by extracellular pH only. Application of inhibitors of either channel mimicked many of the effects of acidification in isolated cells and neurons in situ. We also detected evidence of a pH-sensitive calcium-activated potassium channel ( IKCa) in neurons in situ. The results of these studies support the hypothesis that IKA initiates the chemosensory response, and IKDR and IKCa prolong the period of activation of CO2-sensitive neurons. Thus multiple potassium channels are inhibited by acidosis, and the combined effect of pH-dependent inhibition of these channels enhances neuronal excitability and mediates CO2 chemosensory responses in H. aspersa. We did not find a single “chemosensory channel,” and the chemosensitive channels that we did find were not unique in any way that we could detect. The protein “machinery” of CO2 chemosensitivity is probably widespread among neurons, and the selection process whereby a neuron acts or does not act as a respiratory CO2 chemosensor probably depends on the resting membrane potential and synaptic connectivity.
A computational analysis of central CO2 chemosensitivity in Helix aspersa
Authors: Chernov Mykyta M. , Daubenspeck J. Andrew , Denton Jerod S. , Pfeiffer Jason R. , Putnam Robert W. , Leiter J. C.
Published: August 2006

We created a single-compartment computer model of a CO2 chemosensory neuron using differential equations adapted from the Hodgkin-Huxley model and measurements of currents in CO2 chemosensory neurons from Helix aspersa. We incorporated into the model two inward currents, a sodium current and a calcium current, three outward potassium currents, an A-type current ( IKA), a delayed rectifier current ( IKDR), a calcium-activated potassium current ( IKCa), and a proton conductance found in invertebrate cells. All of the potassium channels were inhibited by reduced pH. We also included the pH regulatory process to mimic the effect of the sodium-hydrogen exchanger (NHE) described in these cells during hypercapnic stimulation. The model displayed chemosensory behavior (increased spike frequency during acid stimulation), and all three potassium channels participated in the chemosensory response and shaped the temporal characteristics of the response to acid stimulation. pH-dependent inhibition of IKA initiated the response to CO2, but hypercapnic inhibition of IKDR and IKCa affected the duration of the excitatory response to hypercapnia. The presence or absence of NHE activity altered the chemosensory response over time and demonstrated the inadvisability of effective intracellular pH (pHi) regulation in cells designed to act as chemostats for acid-base regulation. The results of the model indicate that multiple channels contribute to CO2 chemosensitivity, but the primary sensor is probably IKA. pHi may be a sufficient chemosensory stimulus, but it may not be a necessary stimulus: either pHi or extracellular pH can be an effective stimuli if chemosensory neurons express appropriate pH-sensitive channels. The lack of pHi regulation is a key feature determining the neuronal activity of chemosensory cells over time, and the balanced lack of pHi regulation during hypercapnia probably depends on intracellular activation of pHi regulation but extracellular inhibition of pHi regulation. These general principles are applicable to all CO2 chemosensory cells in vertebrate and invertebrate neurons.
Protein kinase D2 mediates lysophosphatidic acid-induced interleukin 8 production in nontransformed human colonic epithelial cells through NF-κB
Authors: Chiu Terence T. , Leung Wai Yin , Moyer Mary Pat , Strieter Robert M. , Rozengurt Enrique
Published: August 2006

The signaling pathways mediating lysophosphatidic acid (LPA)-stimulated PKD2 activation and the potential contribution of PKD2 in regulating LPA-induced interleukin 8 (IL-8) secretion in nontransformed, human colonic epithelial NCM460 cells were examined. Treatment of serum-deprived NCM460 cells with LPA led to a rapid and striking activation of PKD2, as measured by in vitro kinase assay and phosphorylation at the activation loop (Ser706/710) and autophosphorylation site (Ser876). PKD2 activation induced by LPA was abrogated by preincubation with selective PKC inhibitors GF-I and Ro-31-8220 in a dose-dependent manner. These inhibitors did not have any direct inhibitory effect on PKD2 activity. LPA induced a striking increase in IL-8 production and stimulated NF-κB activation, as measured by NF-κB-DNA binding, NF-κB-driven luciferase reporter activity, and IκBα phosphorylation. PKD2 gene silencing utilizing small interfering RNAs targeting distinct PKD2 sequences dramatically reduced LPA-stimulated NF-κB promoter activity and IL-8 production. PKD2 activation is a novel early event in the biological action of LPA and mediates LPA-stimulated IL-8 secretion in NCM460 cells through a NF-κB-dependent pathway. Our results demonstrate, for the first time, the involvement of a member of the PKD family in the production of IL-8, a potent proinflammatory chemokine, by epithelial cells.
ATP-dependent sugar transport complexity in human erythrocytes
Authors: Leitch Jeffry M. , Carruthers Anthony
Published: August 2006

Human erythrocyte glucose sugar transport was examined in resealed red cell ghosts under equilibrium exchange conditions ([sugar]intracellular = [sugar]extracellular, where brackets indicate concentration). Exchange 3- O-methylglucose (3MG) import and export are monophasic in the absence of cytoplasmic ATP but are biphasic when ATP is present. Biphasic exchange is observed as the rapid filling of a large compartment (66% cell volume) followed by the slow filling of the remaining cytoplasmic space. Biphasic exchange at 20 mM 3MG eliminates the possibility that the rapid exchange phase represents ATP-dependent 3MG binding to the glucose transport protein (GLUT1; cellular [GLUT1] of ≤20 μM). Immunofluorescence-activated cell sorting analysis shows that biphasic exchange does not result from heterogeneity in cell size or GLUT1 content. Nucleoside transporter-mediated uridine exchange proceeds as rapidly as 3MG exchange but is monoexponential regardless of cytoplasmic [ATP]. This eliminates cellular heterogeneity or an ATP-dependent, nonspecific intracellular diffusion barrier as causes of biphasic exchange. Red cell ghost 3MG and uridine equilibrium volumes (130 fl) are unaffected by ATP. GLUT1 intrinsic activity is unchanged during rapid and slow phases of 3MG exchange. Two models for biphasic sugar transport are presented in which 3MG must overcome a sugar-specific, physical (diffusional), or chemical (isomerization) barrier to equilibrate with cell water. Partial transport inhibition with the use of cytochalasin B or maltose depresses both rapid and slow phases of transport, thereby eliminating the physical barrier hypothesis. We propose that biphasic 3MG transport results from ATP-dependent, differential transport of 3MG anomers in which Vmax/apparent Km for β-3MG exchange transport is 19-fold greater than Vmax/apparent Km for α-3MG transport.
Serum response factor: master regulator of the actin cytoskeleton and contractile apparatus
Authors: Miano Joseph M. , Long Xiaochun , Fujiwara Keigi
Published: August 2006

Serum response factor (SRF) is a highly conserved and widely expressed, single copy transcription factor that theoretically binds up to 1,216 permutations of a 10-base pair cis element known as the CArG box. SRF-binding sites were defined initially in growth-related genes. Gene inactivation or knockdown studies in species ranging from unicellular eukaryotes to mice have consistently shown loss of SRF to be incompatible with life. However, rather than being critical for proliferation and growth, these genetic studies point to a crucial role for SRF in cellular migration and normal actin cytoskeleton and contractile biology. In fact, recent genomic studies reveal nearly half of the >200 SRF target genes encoding proteins with functions related to actin dynamics, lamellipodial/filopodial formation, integrin-cytoskeletal coupling, myofibrillogenesis, and muscle contraction. SRF has therefore emerged as a dispensable transcription factor for cellular growth but an absolutely essential orchestrator of actin cytoskeleton and contractile homeostasis. This review summarizes the recent genomic and genetic analyses of CArG-SRF that support its role as an ancient, master regulator of the actin cytoskeleton and contractile machinery.
Central efferent pathways mediating skin cooling-evoked sympathetic thermogenesis in brown adipose tissue
Authors: Nakamura Kazuhiro , Morrison Shaun F.
Published: August 2006

Control of thermoregulatory effectors by the autonomic nervous system is a critical component of rapid cold-defense responses, which are triggered by thermal information from the skin. However, the central autonomic mechanism driving thermoregulatory effector responses to skin thermal signals remains to be determined. Here, we examined the involvement of several autonomic brain regions in sympathetic thermogenic responses in brown adipose tissue (BAT) to skin cooling in urethane-chloralose-anesthetized rats by monitoring thermogenic [BAT sympathetic nerve activity (SNA) and BAT temperature], metabolic (expired CO2), and cardiovascular (arterial pressure and heart rate) parameters. Acute skin cooling, which did not reduce either rectal (core) or brain temperature, evoked increases in BAT SNA, BAT temperature, expired CO2, and heart rate. Skin cooling-evoked thermogenic, metabolic, and heart rate responses were inhibited by bilateral microinjections of bicuculline (GABAA receptor antagonist) into the preoptic area (POA), by bilateral microinjections of muscimol (GABAA receptor agonist) into the dorsomedial hypothalamic nucleus (DMH), or by microinjection of muscimol, glycine, 8-OH-DPAT (5-HT1A receptor agonist), or kynurenate (nonselective antagonist for ionotropic excitatory amino acid receptors) into the rostral raphe pallidus nucleus (rRPa) but not by bilateral muscimol injections into the lateral/dorsolateral part or ventrolateral part of the caudal periaqueductal gray. These results implicate the POA, DMH, and rRPa in the central efferent pathways for thermogenic, metabolic, and cardiac responses to skin cooling, and suggest that these pathways can be modulated by serotonergic inputs to the medullary raphe.
Rapid and Long-Lasting Plasticity of Input-Output Mapping
Authors: Yamamoto Kenji , Hoffman Donna S. , Strick Peter L.
Published: August 2006

Skilled use of tools requires us to learn an “input-output map” for the device, i.e., how our movements relate to the actions of the device. We used the paradigm of visuo-motor rotation to examine two questions about the plasticity of input-output maps: 1) does extensive practice on one mapping make it difficult to modify and/or to form a new input-output map and 2) once a map has been modified or a new map has been formed, does this map survive a gap in performance? Humans and monkeys made wrist movements to control the position of a cursor on a computer monitor. Humans practiced the task for ∼1.5 h; monkeys practiced for 3–9 yr. After this practice, we gradually altered the direction of cursor movement relative to wrist movement while subjects moved either to a single target or to four targets. Subjects were unaware of the change in cursor–movement relationship. Despite their prior practice on the task, the humans and the monkeys quickly adjusted their motor output to compensate for the visuo-motor rotation. Monkeys retained the modified input-output map during a 2-wk gap in motor performance. Humans retained the altered map during a gap of >1 yr. Our results show that sensorimotor performance remains flexible despite considerable practice on a specific task, and even relatively short-term exposure to a new input-output mapping leads to a long-lasting change in motor performance.
Responses of Neurons in the Rat's Ventral Nucleus of the Lateral Lemniscus to Amplitude-Modulated Tones
Authors: Zhang Huiming , Kelly Jack B.
Published: August 2006

Recordings were made from single neurons in the rat's ventral nucleus of the lateral lemniscus (VNLL) to determine responses to amplitude-modulated (AM) tones. The neurons were first characterized on the basis of their response to tone bursts presented to the contralateral ear and a distinction was made between those with transient onset responses and those with sustained responses. Sinusoidal AM tones were then presented to the contralateral ear with a carrier that matched the neuron's characteristic frequency (CF). Modulation transfer functions were generated on the basis of firing rate (MTFFR) and vector strength (MTFVS). Ninety-two percent of onset neurons that responded continuously to AM tones had band-pass MTFFRs with best modulation frequencies from 10 to 300 Hz. Fifty-four percent of sustained neurons had band-pass MTFFRs with best modulation frequencies from 10 to 500 Hz; other neurons had band-suppressed, all-pass, low-pass, or high-pass functions. Most neurons showed either band-pass or low-pass MTFVS. Responses were well synchronized to the modulation cycle with maximum vector strengths ranging from 0.37 to 0.98 for sustained neurons and 0.78 to 0.99 for onset neurons. The upper frequency limit for response synchrony was higher than that reported for inferior colliculus, but lower than that seen in more peripheral structures. Results suggest that VNLL neurons, especially those with onset responses to tone bursts, are sensitive to temporal features of sounds and narrowly tuned to different modulation rates. However, there was no evidence of a topographic relation between dorsoventral position along the length of VNLL and best modulation frequency as determined by either firing rate or vector strength.
Fast Modulation of Prefrontal Cortex Activity by Basal Forebrain Noncholinergic Neuronal Ensembles
Authors: Lin Shih-Chieh , Gervasoni Damien , Nicolelis Miguel A. L.
Published: August 2006

Traditionally, most basal forebrain (BF) functions have been attributed to its cholinergic neurons. However, the majority of cortical-projecting BF neurons are noncholinergic and their in vivo functions remain unclear. We investigated how BF modulates cortical dynamics by simultaneously recording ≤50 BF single neurons along with local field potentials (LFPs) from the prefrontal cortex (PFCx) in different wake–sleep states of adult rats. Using stereotypical spike time correlations, we identified a large (roughly 70%) subset of BF neurons, which we named BF tonic neurons (BFTNs). BFTNs fired tonically at 2–8 Hz without significantly changing their average firing rate across wake–sleep states. As such, these cannot be classified as cholinergic neurons. BFTNs substantially increased the spiking variability during waking and rapid-eye-movement sleep, by exhibiting frequent spike bursts with <50-ms interspike interval. Spike bursts among BFTNs were highly correlated, leading to transient population synchronization events of BFTN ensembles that lasted on average 160 ms. Most importantly, BFTN synchronization occurred preferentially just before the troughs of PFCx LFP oscillations, which reflect increased cortical activity. Furthermore, BFTN synchronization was accompanied by transient increases in prefrontal cortex gamma oscillations. These results suggest that synchronization of BFTN ensembles, which are likely to be formed by cortical-projecting GABAergic neurons from the BF, could be primarily responsible for fast cortical modulations to provide transient amplification of cortical activity.
Predicting 2D Target Velocity Cannot Help 2D Motion Integration for Smooth Pursuit Initiation
Authors: Montagnini Anna , Spering Miriam , Masson Guillaume S.
Published: August 2006

Smooth pursuit eye movements reflect the temporal dynamics of bidimensional (2D) visual motion integration. When tracking a single, tilted line, initial pursuit direction is biased toward unidimensional (1D) edge motion signals, which are orthogonal to the line orientation. Over 200 ms, tracking direction is slowly corrected to finally match the 2D object motion during steady-state pursuit. We now show that repetition of line orientation and/or motion direction does not eliminate the transient tracking direction error nor change the time course of pursuit correction. Nonetheless, multiple successive presentations of a single orientation/direction condition elicit robust anticipatory pursuit eye movements that always go in the 2D object motion direction not the 1D edge motion direction. These results demonstrate that predictive signals about target motion cannot be used for an efficient integration of ambiguous velocity signals at pursuit initiation.
Raphe Magnus Neurons Help Protect Reactions to Visceral Pain From Interruption by Cutaneous Pain
Authors: Brink Thaddeus S. , Hellman Kevin M. , Lambert Aaron M. , Mason Peggy
Published: August 2006

Suppression of reactions to one noxious stimulus by a spatially distant noxious stimulus is termed heterotopic antinociception. In lightly anesthetized rats, a noxious visceral stimulus, colorectal distension (CRD), suppressed motor withdrawals but not blood pressure or heart rate changes evoked by noxious hindpaw heat. Microinjection of muscimol, a GABAAreceptor agonist, into raphe magnus (RM) reduced CRD-evoked suppression of withdrawals, evidence that RM neurons contribute to this heterotopic antinociception. To understand how brain stem neurons contribute to heterotopic antinociception, RM neurons were recorded during CRD-elicited suppression of hindpaw withdrawals. Although subsets of RM neurons that were excited (on cells) or inhibited (off cells) by noxious cutaneous stimulation were either excited or inhibited by CRD, on cells were inhibited and off cells excited by an intracerebroventricularly administered opioid, evidence that the nociception-facilitating and -inhibiting functions of on and off cells, respectively, are predicted by the cellular response to noxious cutaneous stimulation alone and not by the response to CRD. When recorded during CRD-elicited antinociception, RM cell discharge resembled the pattern observed in response to CRD stimulation alone. However, when hindpaw withdrawal suppression was incomplete, RM cell discharge resembled the pattern observed in response to heat alone. We propose that on cells excited by CRD facilitate responses to CRD itself, which in turn augments excitation of off cells that then act to suppress cutaneous nociception. RM cells may thereby contribute to the dominance of quiet recuperative reactions evoked by potentially life-threatening visceral stimuli over transient somatomotor activity elicited by less-injurious noxious cutaneous stimuli.
State-Dependent Modulation of Time-Varying Gustatory Responses
Authors: Fontanini Alfredo , Katz Donald B.
Published: August 2006

Sensory processing is modulated by attention, which is a function of network states. Here we show that changes in such states do more than a simple gating of stimuli: they actually re-arrange cortical coding space to emphasize emotional valences. We delivered taste stimuli to rats before and after a spontaneous state change (“disengagement”) that is associated with a reduction in attention and a concurrent emergence of cortical μ rhythms. The percentage of cortical neurons that responded to tastes, and the average response across neurons, remained stable with disengagement, but the particulars of the responses changed drastically. The distinctiveness of sucrose and quinine—which represent the high and low ends of the palatability spectrum—increased, the distinctiveness of the two aversive tastes (quinine and citric acid) decreased, and the distinctiveness of sucrose and NaCl, which were almost identically palatable to start with, did not change. Overall, then, the changes appeared to be palatability-specific. Two additional findings were consistent with this conclusion: rats’ palatability-related behavioral responses to the tastes changed in similar ways with disengagement and disengagement-related neural changes specifically appeared late in the response, when palatability-specific information emerges in cortical responses. These data suggest that neural state changes can change the content of neural codes.
Francis of Marchia and William of Ockham: Fragments from a Dialogue
Authors: Lambertini Roberto
Published: August 2006

It is well known that Francis of Marchia and William of Ockham joined Michael of Cesena's rebellion against the pope, together escaping from Avignon and signing documents supporting Cesena's defence of Franciscan poverty. The relationship between the works of the two thinkers, on the other hand, is the subject of ongoing investigation. After discussing Francis' rejection in his Commentary on the Sentences of Ockham's theory of quantity, this paper shows how Francis' Improbatio became a source for Ockham's Opus Nonaginta Dierum. Building on Offler's ground-breaking critical edition of the latter work, it is argued that Ockham made extensive use of Francis' Improbatio, even though on several points he felt it necessary to reformulate the arguments of his confrère or even to substantially modify his positions. The two Franciscan theologians differed deeply both in their basic philosophical commitments and in their methodological attitude. These differences emerged even when they were—so to speak—fighting on the same front.
Utrum inhaerentia sit de essentia accidentis. Francis of Marchia and the Debate on the Nature of Accidents
Authors: Amerini Fabrizio
Published: August 2006

This paper attempts to provide a general reconstruction of Francis of Marchia's doctrine of accidental being. The paper is divided into two parts. (1) In the first part, I begin by reconstructing the debate on the nature of accidents held before Marchia, showing that such a debate is characterised by a progressive shift concerning the way to understand accidents. While the first Aristotelian interpreters regard accidents especially as inhering modes of being of substances, the majority of theologians and philosophers in the second half of the thirteenth century regard accidents as absolute beings. For them, the problem is no longer to explain if and, if so, how accidents can be distinct from substances, but how accidents and substances can make some one thing. Metaphysically, their primary focus is on explaining what the ontological status of inherence is. Although it is especially the consideration of the Eucharistic case that induces this change, I point out that many philosophers and theologians find in Aristotle's texts the philosophical support for taking this step. (2) In the second part, I focus more closely on Marchia's doctrine, arguing that Marchia's position is a slightly revised version of Scotus's. Unlike Aquinas and Bonaventure, Marchia explains Aristotle's metaphysics of accidents by way of the metaphysics of the Eucharist and not vice versa. So, in order to explain the philosophical consistency of this miraculous case, Marchia maintains that one does not need to modify the notion of inherence by distinguishing actual from potential inherence and including the latter in the accident's essence; rather it is necessary to take the case of the Eucharist seriously and, on this basis, to remove inherence totally from an accident's essence. In conclusion, the Eucharist shows that accidents are absolute beings to which actual inherence pertains contingently, potential inherence necessarily. But like Scotus's, Marchia's doctrine faces some difficulties that remain unresolved.
Francis of Marchia's Virtus derelicta and the Context of Its Development
Authors: Schabel Chris
Published: August 2006

This article offers the first critical edition of the most important version of Francis of Marchia's famous question 1 of his commentary on Book IV of the Sentences, in which the Franciscan theologian puts forth his virtus derelicta theory of projectile motion. The introduction attempts to place Marchia's theory in its proper context. The theory might seem to us an obvious improvement on Aristotle, but rather than an immediate and complete break with tradition that all scholastics quickly adopted, Marchia's virtus derelicta was more a stage in a gradual process that had begun many decades before and did not find universal acceptance among his first successors. Moreover, Marchia himself did not take the theory to what might seem the obvious conclusion that Jean Buridan would draw, because Marchia employed the virtus derelicta to explain more phenomena than just projectile motion.
Francis of Marchia on the Heavens
Authors: Thakkar Mark
Published: August 2006

Francis of Marchia (c. 1290-1344) is said to have challenged Aristotelian orthodoxy by uniting the celestial and terrestrial realms in a way that has important implications for the practice of natural philosophy. But this over-looks Marchia's vital distinction between bare potentiality, which is actualizable only by God, and natural potency, which is the concern of the natural philosopher. If due attention is paid to this distinction and to its implications, Marchia's position no longer seems to be revolutionary.
How Is Strength of the Will Possible? Concerning Francis of Marchia and the Act of the Will
Authors: Robiglio Andrea
Published: August 2006

Francis of Marchia dealt at length in several different contexts with the nature of the will and willing. Here I examine just one of those discussions: the possibility for the will to go against reason's final judgment, a topic related to weakness of will and the source of sin. Marchia is clearly of a voluntaristic bent, holding that the will can indeed act against the determination of reason. After examining Marchia's argumentation for his position, I explore some of the background to Marchia's view in a distinctively later medieval understanding of the human mind as a system of internal acts and dispositions, with the possibility that several of them belong to the same faculty simultaneously. This increasingly complex conceptualisation of the mind mirrors a new, more complex conceptualization of the "Self".
Francis of Marchia, Virtus derelicta, and Modifications of the Basic Principles of Aristotelian Physics
Authors: Zanin Fabio
Published: August 2006

This article takes as its point of departure the conviction that late medieval science should be studied in its own right, and not merely to determine whether it presaged developments in early modern science. Case in point: Francis of Marchia's theory of virtus derelicta, the theory that the motion of a projectile through the air is due to a force left behind by the original motive force. Certainly, Marchia's view is not a forerunner of inertia. Nevertheless, it is argued that virtus derelicta breaks with two important Aristotelian principles of motion: "everything that has a beginning must necessarily also have an end" and "form is always indivisible." Thus, virtus derelicta is neither an Aristotelian solution to the problem of projectile motion nor a development on the road to early modern science; it belongs to a new (but subsequently undeveloped) understanding of motion.
New Heterocyclic Polyurethane-ureas Based on 4,4'-dibenzyl diisocyanate. 2. Influence of Pyridine Units on the Mechanical Properties
Authors: Scorţanu Elena , Prisăcariu Cristina , Hitruc Elena Gabriela , Caraculacu Adrian A.
Published: August 2006

Heterocyclic polyurethane-ureas containing pyridine units on the main chain have been prepared by a two-step polyadition reaction. First, an urethane prepolymer was prepared in bulk starting from a macrodiol, which was a polyester-diol such as poly(ethylene adipate) (PEA) or a polyether-diol such as poly(tetramethylene glycol) (PTMG), and a diisocyanate such as 4,4'-dibenzyl diisocyanate (DBDI) or 4,4'-methylene-bis(phenyl-isocyanate) (MDI). The resulting urethane prepolymer containing NCO end groups was polymerized afterwards in DMF solution by using 2,6-diamino pyridine (DAPy) as chain extender, leading to polyurethane-ureas containing pyridine units The hard segments contents varied between 1.458–1.967 mol NHCOO/1000 g polymer. The resulting polymers were characterized by IR spectra, elemental and thermogravimetric analyses, differential scanning calorimetry, gel permeation chromatography, inherent viscosity, water retention measurements and mechanical properties. The study of the relationship between structure and properties reveals the influence of the nature of starting materials, macrodiols, the heterocyclic diamine and diisocyanates on the mechanical properties of the polymers. The large number of hydrogen bondings that formed between urea and urethane groups and the presence of pyridine rings in the polymer chain induced an improved thermal stability and good mechanical properties. The influence of the hard segment length was also studied. A greater length of the hard segments led to higher values of some mechanical tests such as: 100 and 300% moduli, strength stress and elongation at break. The mechanical behavior of these polymers is discussed and compared with that of earlier reported linear polyurethane-ureas based on MDI or with that of related polyurethanes chain-extended with diols.
Synthesis and Characterization of Novel Polyimides Containing Anthracene Moiety
Authors: Hariharan Ramalingam , Bhuvana Sowrirajulu , Amutha Nagarajan , Sarojadevi Muthusamy
Published: August 2006

A new type of anthracene containing diamine monomer bis (4-amino 3,5 dimethyl phenyl) anthra methane was prepared by adopting a new procedure starting from 9-anthraldehyde and 2,6-dimethyl aniline. The diamine was reacted with a number of aromatic dianhydrides to form polyimides via a two step polycondensation method involving the formation of poly (amic acid) as the first step and the thermal imidization as the second step. During thermal imidization the temperature was increased stepwise leading to the formation of the polyimide in good yield. Films were made from the prepared poly (amic acid). The Tg values of the polyimides were found to be in the range of 265–294°C, the T10 values were in the range of 396–492°C indicating better thermal stability. They were readily soluble in DMAc, DMF, DMSO, THF, CHCl3, m-cresol and pyridine. The tensile properties of the polyimide films are in the range of 66.2–92.3 MPa ensuring good mechanical properties.
Organo-Soluble Fluorinated Polyimides Derived from Bis-Trifluoromethyl-Substituted Aromatic Diamines and Various Aromatic Dianhydrides
Authors: Liu Jin-Gang , Zhao Xiao-Juan , Li Hong-Shen , Fan Lin , Yang Shi-Yong
Published: August 2006

A new diamine monomer with bis-trifluoromethyl-substituted phenyl in the side chain, α,α-bis (4-amino-3,5-dimethylphenyl)-3′,5′-bis(trifluoromethyl)phenyl methane (6FMA) was successfully synthesized. A series of fluorinated polyimides (PI-IIa-d) were prepared by reacting the diamine with various aromatic dianhydrides. For comparison, another series of polyimides (PI-Ia-d) derived from another diamine with single-trifluoromethyl-substituted phenyl in the side chain, α,α-bis(4-amino-3,5-dimethylphenyl)-3′-trifluoromethyl phenyl methane and the same dianhydrides were also synthesized. The polymers were characterized by inherent viscosity, elemental analysis, Fourier transform-infrared, X-ray, ultraviolet-visible analysis, moisture absorption, thermogravimetric analysis, and differential scanning calorimetry measurements. It was shown that PI-II polyimides exhibited good film formability, enhanced solubility, good thermal stability, superior optical transparency, and acceptable mechanical properties. In addition, the polyimides derived from 3,3′,4,4′-benzophenone tetracarboxylic dianhydride and 6FMA showed high sensitivity to i-line (365 nm) of a high-pressure mercury lamp. The combined properties of the polyimides make them good candidates for microelectronic fabrications.
Synthesis and Properties of Novel Aromatic Copolyamides Derived from 2-(4-carboxyphenyl)-4-[3-phenyl-4-(4-carboxyphenoxyl) phenyl]-phthalazinone
Authors: Liu Pengtao , Liang Qizhen , Liu Cheng , Jian Xigao
Published: August 2006

A series of four novel aromatic copolyamides were synthesized by the direct polycondensation of 2-(4-carboxyphenyl)-4-[3-phenyl-4-(4-carboxyphenoxyl)phenyl]-phthalazinone (1) and terephthalic acid (TPA) with some commercial diamines. The inherent viscosities of the polyamides were between 0.91 and 2.77 dL g-1. All the copolyamides showed an amorphous nature as evidenced by wide-angle X-ray diffraction. Introduction of the non-coplanar phthalazinone segments into the polymer main chains remarkably improved the solubility of aromatic copolyamides. Most of the copolymers were soluble in aprotic polar solvents, such as N-methyl-pyrrolidone (NMP), N, N-dimethylacetamide, and dimethylsulfoxide. These aromatic copolyamides showed high thermal properties associated with the glass transition temperatures ( Tg) in the range of 261–307°C and 10% weight loss temperatures in N2 over 481°C. Moreover, the Tg values of the copolyamides increased with the increasing ratio of phthalazinone moiety in the main chain. Some polymer films cast from NMP solution had tensile strengths up to 244.4 MPa, initial moduli up to 5.08 GPa, and elongation at break values up to 9.9%.
Synthesis and Characterization of Ladder-like Poly(vinylsilsesquioxanes)
Authors: Liu Lei , Hu Yuan , Song Lei
Published: August 2006

Ladder-like poly(vinylsilsesquioxanes)(LPVS) containing four parallel chains in the skeleton were synthesized by two steps: first, LPVS were prepared by a template sol–gel method from vinyltrichlorosilane (VTCS); then adjacent pendent vinyl groups were polymerized side by side along the LPVS chain. The resulting polymers (LPVS-2) were characterized by Fourier transform infrared, 1H NMR, 29Si NMR, thermogravimetric analysis (TGA), transmission electron microscopy, scanning electron microscopy, X-ray diffraction and elemental analysis. Experimental results reveal that both LPVS and LPVS-2 have a highly regular, ladder-like framework, and that most of the vinyl groups have taken part in the side-by-side polymerization reaction. There is no evidence that crosslinking between macromolecular chains has occurred during this process. TGA data indicate that LPVS-2 (with pendent vinyl polymerized) possesses better thermal stability than that of LPVS. For the former, no weight loss can be detected until 500°C, which is attributed to its highly regular ladder-like framework consisting of a four-parallel-chain structure.
Levels of intrinsic coagulation factors and the risk of myocardial infarction among men: opposite and synergistic effects of factors XI and XII
Authors: Doggen Carine J. M. , Rosendaal Frits R. , Meijers Joost C. M.
Published: August 2006

The role of the intrinsic coagulation system on the risk of myocardial infarction is unclear. In the Study of Myocardial Infarctions Leiden (SMILE) that included 560 men younger than age 70 with a first myocardial infarction and 646 control subjects, we investigated the risk of myocardial infarction for levels of factor XI (factor XIc) and factor XII (factor XIIc). Furthermore, the risks for factor VIII activity (factor VIIIc) and factor IX activity (factor IXc) were assessed. Factor XIc was 113.0% in patients compared with 109.8% in control subjects (difference, 3.2%; 95% CI, 1.1%-5.4%). The risk of myocardial infarction adjusted for age for men in the highest quintile compared with those in the lowest quintile was 1.8-fold increased (ORadj, 1.8; 95% CI, 1.2-2.7). In contrast, factor XIIc among patients with myocardial infarction was lower than in control subjects, respectively, 93.0% and 98.6% (difference, 5.6%; 95% CI, 3.3%-7.9%). The odds ratio of myocardial infarction for men in the highest quintile versus those in the lowest quintile was 0.4 (ORadj, 0.4; 95% CI, 0.2-0.5). The highest risk was found among men with both high factor XIc and low factor XIIc (analyses in tertiles: ORadj, 6.4; 95% CI, 2.2-18.0). Factor VIIIc increased the risk of myocardial infarction although not dose dependently. Factor IXc increased the risk; odds ratio of myocardial infarction for men in the highest quintile versus those in the lowest quintile was 3.2 (ORadj, 3.2; 95% CI, 2.0-5.1). Thus, factors XIc and XIIc have opposite and synergistic effects on the risk of myocardial infarction in men; factor VIIIc and factor IXc increase the risk.