CiteULike: Author Grace

Portal hypertension and variceal bleeding: an AASLD single topic symposium.

ND Grace — 2008-07-11T05:57:01-00:00

Hepatology (Baltimore, Md.), Vol. 28, No. 3. (September 1998), pp. 868-880.

Formation of Regulatory Patterns During Signal Propagation in a Mammalian Cellular Network

Avi Ma'ayan — 2005-08-15T16:01:14-00:00

Science, Vol. 309, No. 5737. (12 August 2005), pp. 1078-1083.

We developed a model of 545 components (nodes) and 1259 interactions representing signaling pathways and cellular machines in the hippocampal CA1 neuron. Using graph theory methods, we analyzed ligand-induced signal flow through the system. Specification of input and output nodes allowed us to identify functional modules. Networking resulted in the emergence of regulatory motifs, such as positive and negative feedback and feedforward loops, that process information. Key regulators of plasticity were highly connected nodes required for the formation of regulatory motifs, indicating the potential importance of such motifs in determining cellular choices between homeostasis and plasticity.

A generic component model for building systems software

Geoff Coulson — 2008-06-19T16:56:08-00:00

ACM Trans. Comput. Syst., Vol. 26, No. 1. (February 2008), pp. 1-42.

Functional PEG-Modified Thin Films for Biological Detection

AS Anderson — 2008-06-13T13:17:45-00:00

Langmuir, Vol. 24, No. 5. (4 March 2008), pp. 2240-2247.

Abstract: We report a general procedure to prepare functional organic thin films for biological assays on oxide surfaces. Silica surfaces were functionalized by self-assembly of an amine-terminated silane film using both vapor- and solution-phase deposition of 3'-aminopropylmethyldiethoxysilane (APMDES). We found that vapor-phase deposition of APMDES under reduced pressure produced the highest quality monolayer films with uniform surface coverage, as determined by atomic force microscopy (AFM), ellipsometry, and contact angle measurements. The amine-terminated films were chemically modified with a mixture of carboxylic acid-terminated poly(ethylene glycol) (PEG) chains of varying functionality. A fraction of the PEG chains (0.1-10 mol %) terminated in biotin, which produced a surface with an affinity toward streptavidin. When used in pseudo-sandwich assays on waveguide platforms for the detection of Bacillus anthracis protective antigen (PA), these functional PEG surfaces significantly reduced nonspecific binding to the waveguide surface while allowing for highly specific binding. Detection of PA was used to validate these films for sensing applications in both buffer and complex media. Ultimately, these results represent a step toward the realization of a robust, reusable, and autonomous biosensor.

Dynamic reconfiguration in sensor middleware

Paul Grace — 2007-03-05T19:54:24-00:00

(2006), pp. 1-6.

Athletic Involvement and Adolescent Delinquency

Miller — 2007-08-01T16:50:39-00:00

Journal of Youth and Adolescence, Vol. 36, No. 5. (July 2007), pp. 711-723.

Circuit-based framework for understanding neurotransmitter and risk gene interactions in schizophrenia

John Lisman — 2008-05-19T17:48:54-00:00

Trends in Neurosciences, Vol. 31, No. 5. (May 2008), pp. 234-242.

Many risk genes interact synergistically to produce schizophrenia and many neurotransmitter interactions have been implicated. We have developed a circuit-based framework for understanding gene and neurotransmitter interactions. NMDAR hypofunction has been implicated in schizophrenia because NMDAR antagonists reproduce symptoms of the disease. One action of antagonists is to reduce the excitation of fast-spiking interneurons, resulting in disinhibition of pyramidal cells. Overactive pyramidal cells, notably those in the hippocampus, can drive a hyperdopaminergic state that produces psychosis. Additional aspects of interneuron function can be understood in this framework, as follows. (i) In animal models, NMDAR antagonists reduce parvalbumin and GAD67, as found in schizophrenia. These changes produce further disinhibition and can be viewed as the aberrant response of a homeostatic system having a faulty activity sensor (the NMDAR). (ii) Disinhibition decreases the power of gamma oscillation and might thereby produce negative and cognitive symptoms. (iii) Nicotine enhances the output of interneurons, and might thereby contribute to its therapeutic effect in schizophrenia.

Cell Shape and Negative Links in Regulatory Motifs Together Control Spatial Information Flow in Signaling Networks

Susana Neves — 2008-05-17T00:35:12-00:00

Cell, Vol. 133, No. 4. (16 May 2008), pp. 666-680.

Summary The role of cell size and shape in controlling local intracellular signaling reactions, and how this spatial information originates and is propagated, is not well understood. We have used partial differential equations to model the flow of spatial information from the [beta]-adrenergic receptor to MAPK1,2 through the cAMP/PKA/B-Raf/MAPK1,2 network in neurons using real geometries. The numerical simulations indicated that cell shape controls the dynamics of local biochemical activity of signal-modulated negative regulators, such as phosphodiesterases and protein phosphatases within regulatory loops to determine the size of microdomains of activated signaling components. The model prediction that negative regulators control the flow of spatial information to downstream components was verified experimentally in rat hippocampal slices. These results suggest a mechanism by which cellular geometry, the presence of regulatory loops with negative regulators, and key reaction rates all together control spatial information transfer and microdomain characteristics within cells.

Application note: Simulation of corn yields in the Upper Great Lakes Region of the US using a modeling framework

Gene Safir — 2008-05-12T07:37:35-00:00

Comput. Electron. Agric., Vol. 60, No. 2. (March 2008), pp. 301-305.

The Pledge of Allegiance and the Meanings and Limits of Civil Religion

Grace Kao — 2007-03-31T19:15:08-00:00

Journal of the American Academy of Religion, Vol. 75, No. 1. (1 March 2007), pp. 121-149.

New thoughts on managing obesity

PG Kopelman — 2008-04-19T08:58:47-00:00

Gut, Vol. 53, No. 7. (1 July 2004), pp. 1044-1053.

10.1136/gut.2003.021816

Reflection, self-awareness and self-healing in OpenORB

Gordon Blair — 2006-01-21T04:14:02-00:00

(2002), pp. 9-14.

Flow of pulp fibre suspension and slurries: A review

Heping Cui — 2008-04-07T19:06:29-00:00

International Journal of Multiphase Flow, Vol. 33, No. 9. (September 2007), pp. 921-934.

This paper reviews recent experimental and modeling work on biomass multiphase flow of suspensions and slurries. Problems associated with fibre flows (e.g., fibre flocculation, velocity profiles, flow regimes) have received considerable attention for these processes, involving both liquid-solid and gas-liquid-solid systems. Advanced experimental techniques have been employed in efforts to understand the flows. However, each of these experimental techniques is somewhat limited in its application. In the modelling work, mechanistic models, including those based on CFD, are being developed, but turbulence and interactions among particles and between the particles and fluid have so far limited the success of such models. Future work is needed to improve biomass energy and materials conversion processes.

Gender differences in health information needs and decisional preferences in patients recovering from an acute ischemic coronary event.

DE Stewart — 2008-04-07T11:39:35-00:00

Psychosomatic medicine, Vol. 66, No. 1. (b 2004), pp. 42-48.

OBJECTIVE: This study examined gender differences in health information needs and decisional preferences after an acute ischemic coronary event (ICE). METHODS: Patients with ICE, recruited in 12 coronary intensive care units, completed a questionnaire on demographic, disease-related, and psychosocial topics. Six and 12 months later, they completed mailed follow-up questionnaires. RESULTS: Nine hundred six patients completed the baseline questionnaire, 541 (69%) completed the 6-month questionnaire, and 522 (64%) completed the 12-month questionnaire after hospital discharge. Men reported significantly more information received and greater satisfaction with healthcare practitioners meeting their information needs. Women wanted more information than men concerning angina and hypertension. Men wanted more information about sexual function and reported receiving more information about the role of each doctor, test results, treatments, cardiac rehabilitation, and how their families could support their lifestyle changes. Patients who reported receiving more information reported less depressive symptomatology and greater self-efficacy, healthcare satisfaction, and preventive health behaviors. Although most patients of both sexes preferred a shared decision-making role with their physician, the majority felt their doctor had made the main decisions. CONCLUSIONS: Patients after ICE, especially women, reported receiving much less information than they wanted from all health professionals. Most patients wanted a shared or autonomous treatment decision-making role with their doctor, but only a minority experienced this. Clinicians must do better, because meeting patients' information needs and respecting their decisional preferences are shown to be associated with better self-efficacy, satisfaction, and health-promoting behavior.

Prehistoric habitat stability and post-settlement habitat change in a Chesapeake Bay freshwater tidal wetland, USA

Hilgartner — 2006-06-10T23:58:12-00:00

The Holocene, Vol. 16, No. 4. (June 2006), pp. 479-494.

Dopamine-dependent interactions between limbic and prefrontal cortical plasticity in the nucleus accumbens: disruption by cocaine sensitization.

Y Goto — 2008-03-31T08:33:26-00:00

Neuron, Vol. 47, No. 2. (21 July 2005), pp. 255-266.

The prefrontal cortex and the hippocampus exhibit converging projections to the nucleus accumbens and have functional reciprocal connections via indirect pathways. As a result, information processing between these structures is likely to be bidirectional. Using evoked potential measures, we examined the interactions of these inputs on synaptic plasticity within the accumbens. Our results show that the direction of information flow between the prefrontal cortex and limbic structures determines the synaptic plasticity that these inputs exhibit within the accumbens. Moreover, this synaptic plasticity at hippocampal and prefrontal inputs selectively involves dopamine D1 and D2 activation or inactivation, respectively. Repeated cocaine administration disrupted this synaptic plasticity at hippocampal and prefrontal cortical inputs and goal-directed behavior in the spatial maze task. Thus, interactions of limbic-prefrontal cortical synaptic plasticity and its dysfunction within the accumbens could underlie complex information processing deficits observed in individuals following psychostimulant administration.

Dopaminergic modulation of limbic and cortical drive of nucleus accumbens in goal-directed behavior

Yukiori Goto — 2005-05-25T19:50:13-00:00

Nature Neuroscience, Vol. 8, No. 6. (22 May 2005), pp. 805-812.

Exploiting reflection in mobile computing middleware

Licia Capra — 2008-03-25T16:53:10-00:00

SIGMOBILE Mob. Comput. Commun. Rev., Vol. 6, No. 4. (October 2002), pp. 34-44.

NMR TECHNIQUES FOR VERY LARGE PROTEINS AND RNAS IN SOLUTION

Andreas Tzakos — 2008-03-21T22:06:33-00:00

Annual Review of Biophysics and Biomolecular Structure, Vol. 35, No. 1. (2006), pp. 319-342.

Abstract Three-dimensional structure determination of small proteins and oligonucleotides by solution NMR is established. With the development of novel NMR and labeling techniques, structure determination is now feasible for proteins with a molecular mass of up to 100 kDa and RNAs of up to 35 kDa. Beyond these molecular masses special techniques and approaches are required for applying NMR as a multiprobe method for structural investigations of proteins and RNAs. It is the aim of this review to summarize the NMR techniques and approaches available to advance the molecular mass limit of NMR both for proteins (up to 1 MDa) and RNAs (up to 100 kDa). Physical pictures of the novel techniques, their experimental applications, as well as labeling and assignment strategies are discussed and accompanied by future perspectives.

Synaptic interactions among excitatory afferents to nucleus accumbens neurons: hippocampal gating of prefrontal cortical input.

P O'Donnell — 2008-03-12T13:00:07-00:00

J Neurosci, Vol. 15, No. 5 Pt 1. (May 1995), pp. 3622-3639.

The interactions among excitatory inputs arising from the prefrontal cortex, amygdala, and hippocampus, and innervating nucleus accumbens neurons were studied using in vivo intracellular recording techniques. Neurons recorded in the accumbens displayed one of three activity states: (1) silent, (2) spontaneously firing at low, constant rates, or (3) a bistable membrane potential, characterized by alternating periods of activity and silence occurring in concert with spontaneous transitions between two steady-state membrane potentials (average, -77.3 +/- 7.1 mV base, -63.0 +/- 7.4 mV plateau). These neurons also exhibited a high degree of convergence of responses elicited by stimulation of each of the three excitatory inputs tested. Activation of hippocampal afferents, but not cortical, amygdaloid, or thalamic afferents, induced bistable cells to switch to the depolarized (active) state. In contrast, no bistable cells were encountered in the nucleus accumbens following an acute transection of the fornix. Furthermore, microinjection of lidocaine in the vicinity of the hippocampal afferents at the level of the fornix caused a reversible elimination of the plateau phase in bistable cells. These data suggest that hippocampal input is necessary for accumbens neurons to enter a depolarized, active state. Furthermore, activation of prefrontal cortical inputs fail to evoke spike firing in accumbens neurons unless they are in this active state. Consequently, the hippocampus appears to be capable of gating prefrontal corticoaccumbens throughput.

The CO2-balance of boreal, temperate and tropical forests derived from a global database

S Luyssaert — 2007-09-03T22:18:50-00:00

Global Change Biology, Vol. 0, No. ja. (0000)

Abstract Terrestrial ecosystems sequester 2.1 Pg of atmospheric carbon annually. A large amount of the terrestrial sink is realized by forests. However, considerable uncertainties remain regarding the fate of this carbon over both short and long timescales. Relevant data to address these uncertainties are being collected at many sites around the world, but syntheses of these data are still sparse. To facilitate future synthesis activities, we have assembled a comprehensive global database for forest ecosystems, which includes carbon budget variables (fluxes and stocks), ecosystem traits (e.g. leaf area index, age), as well as ancillary site information such as management regime, climate and soil characteristics. This publicly available database can be used to quantify global, regional or biome-specific carbon-budgets; to re-examine established relationships; to test emerging hypotheses about ecosystem functioning (e.g. a constant NEP to GPP ratio); and as benchmarks for model evaluations. In this paper we present the first analysis of this database. We discuss the climatic influences on gross primary production (GPP), net primary production (NPP) and net ecosystem production (NEP) and present the CO2-balances for boreal, temperate and tropical forest biomes based on micrometeorological, ecophysiological and biometric flux and inventory estimates. Globally, GPP of forests benefited from higher temperatures and precipitation whereas NPP saturated above either a threshold of 1500 mm precipitation or a mean annual temperature of 10oC. The global pattern in NEP was insensitive to climate and is hypothesized to be mainly determined by non-climatic conditions such as successional stage, management, site history and site disturbance. In all biomes, closing the CO2-balance required the introduction of substantial biome-specific closure terms. Non-closure was taken as an indication that respiratory processes, advection and non-CO2 carbon fluxes are not presently being adequately accounted for.

A multi-protocol framework for ad-hoc service discovery

Carlos Flores-Cortés — 2007-07-11T10:20:30-00:00

(2006)

ProofChecker: an accessible environment for automata theory correctness proofs

Matthias Stallmann — 2008-02-29T05:52:21-00:00

SIGCSE Bull., Vol. 39, No. 3. (September 2007), pp. 48-52.

The Effect of Wind on Grasses: III. INFLUENCE OF CONTINUOUS DROUGHT OR WIND ON ANATOMY AND WATER RELATIONS IN FESTUCA ARUNDINACEA SCHREB

J Grace — 2008-02-24T12:51:13-00:00

J. Exp. Bot., Vol. 28, No. 2. (1 April 1977), pp. 268-278.

Festuca arundinacea was grown in (a) calm, well watered conditions (b) calm, droughty conditions, and (c) windy, well watered conditions. Wind and drought both resulted in more and smaller stomata per area of leaf, more epidermal appendages, and more marginal sclerenchyma. When leaves were loaded with weights, wind-grown material had a higher Young's modulus and returned more nearly to their original position when the weights were removed. The relationship between water potential,psi , and per cent relative water content (RWC (%)),was determined using a pressure chamber technique: the solute potential was much more negative in the drought and wind treatments, and in the drought treatment the pressure potential reached zero at a higher RWC (%) than in the other treatments. Drought-grown plants had an enhanced ability to conserve water, whereas wind-grown plants had lost much of their ability to restrict water loss. 10.1093/jxb/28.2.268

The Effect of Wind on Grasses: 1. CUTICULAR AND STOMATAL TRANSPIRATION

J Grace — 2008-02-24T11:52:21-00:00

J. Exp. Bot., Vol. 25, No. 3. (1 June 1974), pp. 542-551.

Transpiration of Festuca arundinacea Schreb, strain S170, was measured at two different wind speeds in a controlled-environment wind tunnel. As a result of a wind increase from 1 m s-1 to 3.5 m s-1 above the sward, transpiration gradually increased, especially at night-time. Similar effects were noted in three other grass species. The transpiration increase could be attributed to decreases in stomatal and cuticular resistances, as a result of leaf buffeting. 10.1093/jxb/25.3.542

Pre-implantation genetic testing

Jan Grace — 2008-02-21T11:29:00-00:00

BJOG: An International Journal of Obstetrics and Gynaecology, Vol. 111, No. 11. (2004), pp. 1165-1173.

From the Cover: Slowed conduction and ventricular tachycardia after targeted disruption of the cardiac sodium channel gene Scn5a

Alex Papadatos — 2008-01-22T22:56:31-00:00

Proceedings of the National Academy of Sciences, Vol. 99, No. 9. (30 April 2002), pp. 6210-6215.

Voltage-gated sodium channels drive the initial depolarization phase of the cardiac action potential and therefore critically determine conduction of excitation through the heart. In patients, deletions or loss-of-function mutations of the cardiac sodium channel gene, SCN5A, have been associated with a wide range of arrhythmias including bradycardia (heart rate slowing), atrioventricular conduction delay, and ventricular fibrillation. The pathophysiological basis of these clinical conditions is unresolved. Here we show that disruption of the mouse cardiac sodium channel gene, Scn5a, causes intrauterine lethality in homozygotes with severe defects in ventricular morphogenesis whereas heterozygotes show normal survival. Whole-cell patch clamp analyses of isolated ventricular myocytes from adult Scn5a+/[-] mice demonstrate a [approx]50% reduction in sodium conductance. Scn5a+/[-] hearts have several defects including impaired atrioventricular conduction, delayed intramyocardial conduction, increased ventricular refractoriness, and ventricular tachycardia with characteristics of reentrant excitation. These findings reconcile reduced activity of the cardiac sodium channel leading to slowed conduction with several apparently diverse clinical phenotypes, providing a model for the detailed analysis of the pathophysiology of arrhythmias. 10.1073/pnas.082121299

Hazard Ratio in Clinical Trials

Spotswood Spruance — 2008-01-07T00:35:10-00:00

Antimicrob. Agents Chemother., Vol. 48, No. 8. (1 August 2004), pp. 2787-2792.

10.1128/AAC.48.8.2787-2792.2004

Intracellular and extracellular electrophysiology of nigral dopaminergic neurons--2. Action potential generating mechanisms and morphological correlates.

AA Grace — 2007-12-19T17:30:11-00:00

Neuroscience, Vol. 10, No. 2. (October 1983), pp. 317-331.

Intracellular recordings from identified nigral dopamine neurons in the rat revealed that their potentials are composed of four components: (1) a slow depolarization, (2) an initial segment spike, (3) a somatodendritic spike, and (4) an afterhyperpolarization. By combining intracellular and extracellular recording techniques with anatomical studies using intracellular injections of Lucifer yellow, an attempt was made to localize each of these potentials to various neuronal compartments. Lucifer yellow injections demonstrated that the dopamine neurons recorded have a pyramidal or polygonal shaped soma, 12-30 microns in diameter, with 3-6 thick major dendrites which extend 10-50 microns from the soma before bifurcating. The axon appears to rise from a major dendrite 15-30 microns from the soma. Based on this anatomical configuration, results from the electrophysiological studies suggest that: (1) the slow depolarization is a pacemaker-like conductance most likely localized to the somatic region, (2) the initial segment spike is a low-threshold spike probably located at the axon hillock, (3) the somatodendritic spikes are long duration spikes that rapidly inactivate with depolarization, have a high threshold, and are localized to the dendritic regions. The action potential is then terminated by a long duration afterhyperpolarization. Our data further suggest that spike generation may be initiated by a slow depolarization at the soma triggering a spike in the low-threshold axon hillock which then spreads across the already-depolarized soma to trigger the dendritic spike. Based on the above findings, dopamine neurons can be compartmentalized electrophysiologically and morphologically into subcomponents, each associated with spikes and specific ionic currents. The high threshold dendritic component of the action potential demonstrates rapid inactivation with depolarization, and thus occurs over a rather narrow range of membrane polarization. This limited range of action potential generation may be important in control of dendritic dopamine release and/or modulation of electrical coupling between dopaminergic neurons.

The catechol-O-methyltransferase polymorphism: Relations to the tonic-phasic dopamine hypothesis and neuropsychiatric phenotypes

RM Bilder — 2007-12-12T18:30:00-00:00

Neuropsychopharmacology, Vol. 29, No. 11. (2004), pp. 1943-1961.

Diverse phenotypic associations with the catechol-O-methyltransferase (COMT) Val158Met polymorphism have been reported. We suggest that some of the complex effects of this polymorphism be understood from the perspective of the tonic-phasic dopamine (DA) hypothesis. We hypothesize that the COMT Met allele (associated with low enzyme activity) results in increased levels of tonic DA and reciprocal reductions in phasic DA in subcortical regions and increased D1 transmission cortically. This pattern of effects is hypothesized to yield increased stability but decreased flexibility of neural network activation states that underlie important aspects of working memory and executive functions; these effects may be beneficial or detrimental depending on the phenotype, a range of endogenous factors, and environmental exigencies. The literature on phenotypic associations of the COMT Val158Met polymorphism is reviewed, highlighting areas where this hypothesis may have explanatory value, and pointing to possible directions for refinement of relevant phenotypes and experimental evaluation of this hypothesis.

Selective Activation of Medial Prefrontal-to-Accumbens Projection Neurons by Amygdala Stimulation and Pavlovian Conditioned Stimuli

Vincent Mcginty — 2007-12-10T15:02:00-00:00

Cereb. Cortex (7 December 2007), bhm223.

Medial prefrontal cortex (mPFC) neurons respond to Pavlovian conditioned stimuli, and these responses depend on input from the basolateral amygdala (BLA). In this study, we examined the mPFC efferent circuits mediating conditioned responding by testing whether specific subsets of mPFC projection neurons receive BLA input and respond to conditioned stimuli. In urethane-anesthetized rats, we identified mPFC neurons that projected to the nucleus accumbens (NAcc) or to the contralateral mPFC (cmPFC) using antidromic activation. Stimulation of the BLA and Pavlovian conditioned odors selectively activated a subpopulation of ventral mPFC neurons that projected to NAcc, but elicited virtually no activation in mPFC neurons that projected to cmPFC. BLA stimulation typically evoked inhibitory responses among nonactivated neurons projecting to either site. These results suggest that the ventral mPFC-to-NAcc pathway may support behavioral responses to conditioned cues. Furthermore, because projections from the BLA (which also encode affective information) and the mPFC converge within the NAcc, the BLA may recruit the mPFC to drive specific sets of NAcc neurons, and thereby exert control over prefrontal cortical-striato-thalamocortical information flow. 10.1093/cercor/bhm223

A Component Model for Building Systems Software

G Coulson — 2006-11-04T13:38:14-00:00

(2004)

OpenCOM v2 is our experimental language-independent component-based systems-building technology. OpenCOM offers more than merely a component-based programming model. First, it is a runtime component model and supports dynamic runtime reconfiguration of systems (i.e. one can load, unload, bind, and rebind components at runtime). Second, it explicitly supports the deployment of the model in a wide range of `deployment environments' (e.g. operating systems, PDAs, embedded devices, network...

High-Frequency Deep Brain Stimulation of the Nucleus Accumbens Region Suppresses Neuronal Activity and Selectively Modulates Afferent Drive in Rat Orbitofrontal Cortex In Vivo

Clinton Mccracken — 2007-11-15T18:49:12-00:00

J. Neurosci., Vol. 27, No. 46. (14 November 2007), pp. 12601-12610.

High-frequency deep-brain stimulation (DBS) of the nucleus accumbens (NAc) region is an effective therapeutic avenue for patients with treatment-resistant obsessivecompulsive disorder (OCD). Imaging studies suggest that DBS acts by suppressing the aberrant metabolism in the orbitofrontal cortex (OFC) that is a hallmark of OCD; however, little is known about the mechanisms by which this occurs. We examined the effects of 30 min NAc DBS at 130 Hz on spontaneously active OFC neurons and local field potentials (LFPs) in addition to evoked responses elicited by single-pulse stimulation of the NAc or mediodorsal thalamus (MD) in urethane-anesthetized rats. NAc DBS reduced the mean firing rate of OFC neurons, although neurons receiving monosynaptic input from MD were less affected and some putative interneurons were excited by DBS. Single-pulse stimulation of the NAc produced a robust inhibition in OFC neurons that was attenuated after DBS, whereas excitatory responses were unchanged. In contrast, after DBS inhibitory responses evoked from MD were unchanged, whereas excitatory responses were enhanced. NAc-evoked LFP responses were potentiated after DBS, whereas MD-evoked LFP responses were unchanged. NAc DBS also enhanced OFC spontaneous LFP oscillatory activity in the slow (0.54 Hz) frequency band. These results suggest that DBS of the NAc region may alleviate OCD symptoms by reducing activity in subsets of OFC neurons, potentially by driving recurrent inhibition though antidromic activation of corticostriatal axon collaterals. Moreover, selective potentiation of input to these inhibitory circuits may also contribute to the therapeutic effects produced by DBS in OCD patients. 10.1523/JNEUROSCI.3750-07.2007

Astressin-amide and astressin-acid are structurally different in dimethylsulfoxide.

CR Grace — 2007-11-12T02:37:21-00:00

Biopolymers, Vol. 87, No. 2-3. (5 2007), pp. 196-205.

The C-terminally amidated CRF antagonist astressin binds to CRF-R1 or CRF-R2 receptors with low nanomolar affinity while the corresponding astressin-acid has >100 times less affinity. To understand the role of the amide group in binding, the conformations of astressin-amide and astressin-acid were studied in DMSO using NMR techniques. The 3D NMR structures show that the backbones of both analogs prefer an alpha-helical conformation, with a small kink around Gln(26). However, astressin-amide has a well-defined helical structure from Leu(27) to Ile(41) and a conformation very similar to the bioactive conformation reported by our group (Grace et al., Proc Natl Acad Sci USA 2007, 104, 4858-4863). In contrast, astressin-acid has an irregular helical conformation from Arg(35) onward, including a rearrangement of the side chains in that region. This structural difference highlights the crucial role of the C-terminal amidation for stabilization of astressin's bioactive conformation.

(+)-Methamphetamine increases corticosterone in plasma and BDNF in brain more than forced swim or isolation in neonatal rats.

Curtis E Grace — 2007-11-10T17:12:45-00:00

Synapse, Vol. 62, No. 2. (8 November 2007), pp. 110-121.

(+)-Methamphetamine (MA) administered on postnatal days (P) 11-15 (four times/day) results in increased corticosterone that overlaps the stress hyporesponsive period (SHRP; P2-14) and leads to later learning and memory deficits. Elevated corticosterone during the SHRP results in neurotrophin changes and long-term effects on learning. We determined whether two known stressors could mimic the effects of MA [10 (mg/kg)/dose] administration in neonatal rats. Stressors were four 15-min sessions of forced swim or isolation (confinement in forced swim tubes without water). Saline and weighed-only controls were included and all five treatments were represented within each litter. Corticosterone in plasma and brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) in neostriatum and hippocampus were examined after one or four treatments on P11 or P15 (0.5, 1.75, 6.5, or 24 h after first dose). MA increased corticosterone and BDNF; forced swim and isolation also increased corticosterone, but to a lesser extent than MA, and neither stressor increased BDNF. NGF was unaffected by saline treatment, but there was a minor reduction in NGF in the forced swim group compared with the weighed-only group. The data show that MA is more potent at releasing corticosterone and increasing BDNF than short-term, repeated episodes of forced swim or isolation. The possible relationship between these changes and the long-term cognitive effects of developmental MA administration are discussed. Synapse 62:110-121, 2008. (c) 2008 Wiley-Liss, Inc.

Architectural distribution of foliage in individual Pinus radiata D. Don crowns and the effects of clumping on radiation interception.

D Whitehead — 2007-09-25T07:56:17-00:00

Tree Physiol, Vol. 7, No. 1 2 3 4. (December 1990), pp. 135-155.

The architectural arrangement and leaf area of representative branch units, on one branch complex from each cluster on the stem, were measured on six trees in a widely spaced 7-year-old Pinus radiata D. Don plantation. There was a linear relationship between leaf area and the basal area of branch complexes. Assuming similarity in the arrangement of branch units within concomitant branch complexes at each cluster, the 3-dimensional distribution of leaf area density (leaf area per unit volume) in an array of cubic cells, each 10(-3) m(3), comprising the volume of each tree crown, was reconstructed. The fraction of cells in which foliage was present varied from 0.08 to 0.23 in the crowns with the highest (Tree 4) and lowest (Tree 3) degree of clumping, respectively. This difference was related to the number, length, and leaf area per unit length of Order 3 branch units, in particular. The actual distributions of leaf area density were used with a simple radiative transfer model to estimate the probability of penetration of beam and diffuse photosynthetically active radiation (PAR) through individual tree crowns. The average probability of beam penetration was greater for the tree with the most clumped foliage than for the tree with the least clumped foliage. For both trees, the average probabilities of penetration were greater than the values that would have resulted if a random distribution of foliage had been assumed. The negative binomial model was used to estimate an index of foliage dispersion for the tree crowns. For beam PAR, the index of foliage dispersion was 3.3 and 2.3 for the trees with the most, and the least clumped foliage, respectively. These results were supported by analysis of the architectural arrangement of foliage in the tree crowns. For two days in summer, the assumption that leaf area density was randomly distributed would have resulted in a 20 to 30% overestimation of intercepted PAR flux by the tree crowns.

Regulation of firing of dopaminergic neurons and control of goal-directed behaviors

Anthony Grace — 2007-04-04T14:05:09-00:00

Trends in Neurosciences, Vol. In Press, Corrected Proof

There are several brain regions that have been implicated in the control of motivated behavior and whose disruption leads to the pathophysiology observed in major psychiatric disorders. These systems include the ventral hippocampus, which is involved in context and focus on tasks, the amygdala, which mediates emotional behavior, and the prefrontal cortex, which modulates activity throughout the limbic system to enable behavioral flexibility. Each of these systems has overlapping projections to the nucleus accumbens, where these inputs are integrated under the modulatory influence of dopamine. Here, we provide a systems-oriented approach to interpreting the function of the dopamine system, its modulation of limbic-cortical interactions and how disruptions within this system might underlie the pathophysiology of schizophrenia and drug abuse.

The influence of terrestrial ecosystems on climate

Patrick Meir — 2006-05-16T18:33:47-00:00

Trends in Ecology & Evolution, Vol. 21, No. 5. (May 2006), pp. 254-260.

Terrestrial ecosystems influence climate by affecting how much solar energy is absorbed by the land surface and by exchanging climatically important gases with the atmosphere. Recent model analyses show widespread qualitative agreement that terrestrial ecological processes will have a net positive feedback effect on 21st-century global warming, and, therefore, cannot be ignored in climate-change projections. However, the quantitative uncertainty in the net feedback is large. The uncertainty in 21st-century carbon dioxide emissions resulting from terrestrial carbon cycle-climate feedbacks is second in magnitude only to the uncertainty in anthropogenic emissions. We estimate that this translates into an uncertainty in global warming owing to the land surface of 1.5[deg]C by 2100. We also emphasise the need to improve our understanding of terrestrial ecological processes that influence land-atmosphere interactions at relatively long timescales (decadal-century) as well as at shorter intervals (e.g. hourly).

Oscillation Theory for Difference and Functional Differential

RP Agarwal — 2007-08-08T05:56:07-00:00

(01 May 2000)

This book reviews material from more than three hundred publications on the oscillation theory of difference and functional differential equations of various types. For difference equations, a large number of new concepts are explained and supported by interesting theoretical developments. For differential equations, simplified versions of several new integral criteria for oscillations are presented. Proofs which illustrate the various strategies and ideas involved are given. This book should be a stimulus to the further development of the theory. Audience: This work will be of interest to mathematicians and graduate students in the disciplines of theoretical and applied mathematics.

Can we measure terrestrial photosynthesis from space directly, using spectral reflectance and fluorescence?

J Grace — 2007-07-17T23:38:51-00:00

Global Change Biology, Vol. 13, No. 7. (July 2007), pp. 1484-1497.

Fine-scale spatial variation in plant species richness and its relationship to environmental conditions in coastal marshlands

J Mancera — 2005-06-02T20:28:51-00:00

Vegetatio, Vol. 178, No. 1. (March 2005), pp. 39-50.

Arrhythmogenic mechanisms in the isolated perfused hypokalaemic murine heart

Killeen — 2007-01-15T19:04:02-00:00

Acta Physiologica, Vol. 189, No. 1. (January 2007), pp. 33-46.

Effect of temperature and moisture on rates of carbon mineralization in a Mediterranean oak forest soil under controlled and field conditions

A Rey — 2005-09-18T15:27:47-00:00

European Journal of Soil Science, Vol. 56, No. 5. (October 2005), pp. 589-599.

Cellular mechanisms of infralimbic and prelimbic prefrontal cortical inhibition and dopaminergic modulation of basolateral amygdala neurons in vivo.

JA Rosenkranz — 2007-06-19T17:56:32-00:00

J Neurosci, Vol. 22, No. 1. (1 January 2002), pp. 324-337.

The basolateral amygdala (BLA) is believed to be involved in schizophrenia, depression, and other disorders that display affective components. The neuronal activity of the BLA, and BLA-mediated affective behaviors, are driven by sensory stimuli transmitted in part from sensory association cortical regions. These same behaviors may be regulated by prefrontal cortical (PFC) inputs to the BLA. However, it is unclear how two sets of glutamatergic inputs to the BLA can impose opposing actions on BLA-mediated behaviors; specifically, it is unclear how PFC inputs exert inhibitory actions over BLA projection neurons. Dopamine (DA) receptor activation enhances BLA-mediated behaviors. Although we have demonstrated that DA suppresses medial PFC inputs to the BLA and enhances sensory cortical inputs, the precise cellular mechanisms for its actions are unknown. In this study we use in vivo intracellular recordings to determine the means by which glutamatergic inputs from the PFC inhibit BLA projection neurons, contrast that with glutamatergic inputs from the association sensory cortex (Te3) that drive BLA projection neurons, and examine the effects of DA receptor activation on neuronal excitability, spontaneous postsynaptic potentials (PSPs), and PFC-evoked PSPs. We found that PFC stimulation inhibits BLA projection neurons by three mechanisms: chloride-mediated hyperpolarization, a persistent decrease in neuronal input resistance, and shunting of PSPs; all effects are possibly attributable to recruitment of inhibitory interneurons. DA receptor activation enhanced neuronal input resistance by a postsynaptic mechanism (via DA D2 receptors), suppressed spontaneously occurring and PFC-evoked PSPs (via DA D1 receptors), and enhanced Te3-evoked PSPs.

Sequence and spacing of TATA box elements are critical for accurate initiation from the beta-phaseolin promoter.

ML Grace — 2007-06-19T04:37:43-00:00

J Biol Chem, Vol. 279, No. 9. (27 February 2004), pp. 8102-8110.

The beta-phaseolin (phas) gene, which encodes one of the major seed storage proteins of P. vulgaris, is tightly regulated at the transcription level resulting in strict tissue-specific and spatial expression during embryonic development. The phas proximal promoter contains a complex arrangement of core promoter elements including three TATA boxes as well as several putative initiator elements. To delineate the respective contributions of the core promoter elements to transcription initiation we have performed site-directed mutagenesis of the phas promoter. In vivo expression studies were performed on transgenic Arabidopsis harboring phas promoter mutants driving expression of the beta-glucuronidase (gus) reporter gene. Quantitative assessment of GUS activity in seeds bearing the promoter mutants indicated that both sequence and spacing of the TATA elements influenced the efficiency of transcription. Substitution, insertion or deletion mutations had no effect on histochemical staining patterns indicating that strict spacing requirements are not essential for correct spatial expression of phas during embryogenesis. Further evaluation of the phas promoter by in vitro transcription analysis revealed the presence of multiple TATA-dependent transcription initiation start sites. The distance between TATA elements and transcription start sites was maintained in insertion and deletion mutants through the creation of novel initiation sites, indicating that positioning of the TATA elements rather than DNA sequence was the primary determinant of start site location. We conclude that, while dispensable for proper spatial distribution, the complex architecture of the phas promoter is required to ensure high levels of accurate phas transcription initiation in the developing embryo.

Gender, ethnocultural, and psychosocial barriers to diabetes self-management in Italian women and men with type 2 diabetes.

MG Ponzo — 2007-01-29T12:52:58-00:00

Behav Med, Vol. 31, No. 4. (2006), pp. 153-160.

Although several ethnic groups experience a greater burden of diabetes, this has not been examined in first-generation Italians, who compose one of the largest ethnocultural groups in Canada. In this cross-sectional study, the authors examined the relationship among gender and ethnocultural factors, family support, depressive symptomatology, and illness perceptions on diabetes self-management (DSM) in 50 Italian women and men with type 2 diabetes. The authors first conducted a focus group to explore cultural barriers. They then assessed gender, ethnocultural, and psychosocial barriers quantitatively by an interviewer-administered questionnaire. Compared with Italian men, Italian women reported significantly greater depressive symptomatology and perceived disease seriousness. Greater depressive symptomatology was significantly associated with perceived family sabotage and DSM barriers. In univariate analyses, shorter duration of diabetes and greater perceived treatment effectiveness significantly predicted better DSM. In conclusion, certain illness perceptions and culturally relevant gender-specific barriers should be addressed by health care providers to maximize DSM in this population. Index Terms: diabetes, diet, gender, self-management

Intracellular and extracellular electrophysiology of nigral dopaminergic neurons--1. Identification and characterization.

AA Grace — 2007-05-16T14:19:42-00:00

Neuroscience, Vol. 10, No. 2. (October 1983), pp. 301-315.

Intracellular recordings were obtained from directly identified rat nigral dopamine cells in vivo. This identification was based on an increase in glyoxylic acid-induced catecholamine fluorescence in the impaled dopamine neurons. One of three compounds was injected intracellularly into each cell to produce the heightened fluorescence: (1) L-DOPA, to increase the intracellular dopamine content by precursor loading; (2) tetrahydrobiopterin, a cofactor for tyrosine hydroxylase, to increase intracellular dopamine concentration through activation of the rate-limiting enzyme for dopamine synthesis and (3) colchicine, to arrest intraneuronal transport and thus allow the build-up of dopamine synthesizing enzymes and dopamine in the soma. In addition, dopamine cells were antidromically activated from the caudate nucleus and collision with a directly elicited action potential was demonstrated. Identified dopamine neurons were shown to possess an input resistance of 31.2 +/- 7.4 M omega (means +/- SD) and a time constant of 12.1 +/- 3.2 ms. The action potentials were of long duration (2.75 +/- 0.5 ms) with a marked break between the initial segment and the somatodendritic spike components. The initial segment was the only component commonly elicited during antidromic activation. Spontaneously occurring action potentials were usually preceded by a slow, pacemaker-like depolarization. Burst firing by summation of depolarizing afterpotentials was observed to occur spontaneously, but could not be triggered by short depolarizing current pulses. Intravenously administered apomorphine demonstrated the same inhibitory effect on cell firing that was previously reported to occur when recording extracellularly from identified dopaminergic neurons. The determination of the electrophysiological characteristics of a population of cells directly identified as containing a specific neurotransmitter (in this case, dopamine) may allow one to construct better models of a system's functioning. Thus, the high input resistance and long time constant of dopamine-containing cells, combined with their burst/pause firing mode, may be important functionally with respect to a possible modulatory effect of dopamine in postsynaptic target areas.

The human footprint in the carbon cycle of temperate and boreal forests

Federico Magnani — 2007-06-14T11:35:31-00:00

Nature, Vol. 447, No. 7146. (14 June 2007), pp. 849-851.

Temperate and boreal forests in the Northern Hemisphere cover an area of about 2 times 107 square kilometres and act as a substantial carbon sink (0.6–0.7 petagrams of carbon per year)1. Although forest expansion following agricultural abandonment is certainly responsible for an important fraction of this carbon sink activity, the additional effects on the carbon balance of established forests of increased atmospheric carbon dioxide, increasing temperatures, changes in management practices and nitrogen deposition are difficult to disentangle, despite an extensive network of measurement stations2, 3. The relevance of this measurement effort has also been questioned4, because spot measurements fail to take into account the role of disturbances, either natural (fire, pests, windstorms) or anthropogenic (forest harvesting). Here we show that the temporal dynamics following stand-replacing disturbances do indeed account for a very large fraction of the overall variability in forest carbon sequestration. After the confounding effects of disturbance have been factored out, however, forest net carbon sequestration is found to be overwhelmingly driven by nitrogen deposition, largely the result of anthropogenic activities5. The effect is always positive over the range of nitrogen deposition covered by currently available data sets, casting doubts on the risk of widespread ecosystem nitrogen saturation6 under natural conditions. The results demonstrate that mankind is ultimately controlling the carbon balance of temperate and boreal forests, either directly (through forest management) or indirectly (through nitrogen deposition).

The control of firing pattern in nigral dopamine neurons: burst firing

Aa Grace — 2007-06-10T21:23:12-00:00

J. Neurosci., Vol. 4, No. 11. (1 November 1984), pp. 2877-2890.

Neural response to bird’s own song and tutor song in the zebra finch field L and caudal mesopallium

N Amin — 2007-06-04T23:29:18-00:00

Journal of Comparative Physiology A: Neuroethology, Sensory, Neural, and Behavioral Physiology, Vol. 190, No. 6. (1 June 2004), pp. 469-489.

Neurons in the song system nuclei of songbirds exhibit a strong preference for the sound of the bird’s own song relative to that of conspecific songs. This selectivity is observed in the high vocal center and the nucleus interface of the nidopallium, two song nuclei that receive input from the bird’s auditory system. To investigate the role of the auditory system in generating the selective responses observed in the song system, we recorded auditory responses in the zebra finch primary auditory forebrain, field L, and in a secondary auditory area, the caudal mesopallium. Field L and caudal mesopallium project directly or indirectly to the high vocal center and nucleus interface of the nidopallium and are presumed to provide substantial auditory input to the song system. We found that, on average, neurons in field L and caudal mesopallium did not show positive selective responses for the bird’s own song or tutor song relative to conspecific song. Moreover, there were no particular sub-areas in the auditory telencephalon that were relatively more selective than the average. The selectivity for the bird’s own song would therefore be restricted to song nuclei and would arise in one processing step, potentially found at the interface between the auditory and the song systems.