bluuebunny/crossref_metadata_2025 huggingface dataset:
Fast cerebral functional signal in the 100‐ms range detected in the visual cortex by frequency‐domain near‐infrared spectrophotometry
Authors: Wolf Martin , Wolf Ursula , Choi Jee H. , Toronov Vladislav , Adelina Paunescu L. , Michalos Antonios , Gratton Enrico
Published: June 2003

Brain activity is associated with physiological changes, which alter the optical properties of the tissue in the near‐infrared part of the spectrum. Two major types of optical signals following functional brain activation can be distinguished: a slow signal due to hemodynamic changes and a fast signal, which is directly related to neuronal activity. The fast signal is small and therefore difficult to detect. We used a specially noise‐optimized frequency‐domain near‐infrared spectrometer with a π‐sensor, which was expected to be particularly sensitive to deeper tissue layers, to investigate the human visual cortex during visual stimulation generated by a checkerboard. We were able to detect significant fast signals in single light bundles, but not in π‐signals. The fast signals were mostly collocated with strong slow hemodynamic signals, but showed a higher degree of localization than the latter. The latencies of 40±16 ms of the fast signals were similar between locations. Our results also indicate that the brain responds differently to a single and double (forth and back) reversal of the checkerboard, with a stronger reaction upon the double reversal.
The event‐related optical signal (EROS) in visual cortex: Replicability, consistency, localization, and resolution
Authors: Gratton Gabriele , Fabiani Monica
Published: June 2003

We previously reported a fast and localized noninvasive event‐related optical signal (EROS) elicited by visual field quadrant stimulation in occipital brain areas (Gratton, Corballis, Cho, Fabiani, & Hood, 1995). We now present a replication and extension of that experiment. In addition, we propose a new method for estimating the cross‐validity of the results based on intersubject correlations, report further data on the localization of EROS, and present an analysis of its spatial resolution. The results replicate our original findings. The intersubject correlation is generally quite high (r=.6–.8). The spatial resolution analysis indicates that activities from cortical areas located approximately 1.5 cm apart are measurable independently without cross talk. This study provides further support for the idea that noninvasive optical imaging can be used to derive images of brain activity combining good spatial and temporal resolution.
A generally robust approach to hypothesis testing in independent and correlated groups designs
Authors: Keselman H. J. , Wilcox Rand R. , LIX Lisa M.
Published: June 2003

Standard least squares analysis of variance methods suffer from poor power under arbitrarily small departures from normality and fail to control the probability of a Type I error when standard assumptions are violated. These problems are vastly reduced when using a robust measure of location; incorporating bootstrap methods can result in additional benefits. This paper illustrates the use of trimmed means with an approximate degrees of freedom heteroskedastic statistic for independent and correlated groups designs in order to achieve robustness to the biasing effects of nonnormality and variance heterogeneity. As well, we indicate when a boostrap methodology can be effectively employed to provide improved Type I error control. We also illustrate, with examples from the psychophysiological literature, the use of a new computer program to obtain numerical results for these solutions.
Locus of the effect of temporal preparation: Evidence from the lateralized readiness potential
Authors: MÜller‐Gethmann Hiltraut , Ulrich Rolf , Rinkenauer Gerhard
Published: June 2003

It is well established that reaction time (RT) is shorter when a response signal is preceded by a warning signal, because the warning signal causes the participant to prepare for the upcoming response. A review of chronometric and psychophysiological studies reveals the prevailing view that this temporal preparation operates mainly at a motor level speeding up rather late processes. To assess the locus of this preparation effect, we conducted two experiments employing the lateralized readiness potential (LRP). Contrary to this prevailing view, the results of both experiments clearly indicate that temporal preparation enhances the processing speed of relatively early processes, because a manipulation of temporal uncertainty affected RT, the P300 latency, and the stimulus‐to‐LRP interval but not the LRP‐to‐keypress interval.
Electrophysiological evidence of visual encoding deficits in a cross‐modal attentional blink paradigm
Authors: Dell'acqua R. , Jolicoeur P. , Pesciarelli F. , Job R. , Palomba D.
Published: June 2003

Two experiments are reported in which two target stimuli, T1 and T2, were presented at variable stimulus onset asynchronies (SOAs). In Experiment 1, T1 and T2 were visual stimuli embedded in a rapid serial visual presentation (RSVP) stream of distractors. Participants were asked to report T1 and T2 at the end of the stream. In Experiment 2, T1 was an auditory stimulus, and T2 a visual stimulus embedded in an RSVP stream. Participants made a speeded discriminative response to T1, and reported T2 at the end of the stream. An attentional blink (AB) effect was observed in both experiments: T2 report suffered at short SOA compared to long SOA. During the AB, the amplitude of the P300 component of the event‐related potential (ERP) locked to T2 onset was sensibly reduced in both experiments. Behavioral and ERP results were very similar across the two experiments. Implications for models of the AB effect are discussed.
Influence of phonological expectations during a phoneme deletion task: Evidence from event‐related brain potentials
Authors: Newman R. L. , Connolly J. F. , Service E. , Mcivor K.
Published: June 2003

Several studies have identified a negativity [the phonological mismatch negativity (PMN)] preceding the N400 during auditory sentence comprehension. The present study investigated whether the PMN reflects a prelexical or lexical stage of spoken word recognition. Event‐related brain potentials (ERPs) were recorded to investigate phonological processing independently from lexical/semantic influences during a task requiring metalinguistic analysis of speech stimuli. Participants were instructed to omit the initial phoneme from a word (“clap” without the /k/) after which they heard a correct (lap) or incorrect (cap, ap, nose) answer. The PMN (peaking at 270 ms) was largest to incorrect items and did not differentiate between items that shared the same rime and items that were phonologically unrelated to the correct choice. Further, the PMN did not differ between word (cap) and nonword (ap) choices. The P300 was largest to correct items but was also seen to choices that rhymed with the correct answer. It is concluded that the PMN serves as a neural marker for the analysis of acoustic input merging with prelexical phonemic expectations.
Autonomic recovery and habituation in social anxiety
Authors: Mauss Iris B. , Wilhelm Frank H. , Gross James J.
Published: June 2003

Growing evidence suggests that, contrary to expectation, high trait socially anxious (HTSA) and low trait socially anxious (LTSA) individuals show comparable autonomic reactivity during stressful speech tasks. To test the hypothesis that autonomic differences between groups might emerge during recovery or habituation, 35 HTSA and LTSA participants gave two impromptu speeches. Measures of anxiety experience as well as cardiovascular, electrodermal, respiratory, and vagal activation were obtained. Despite greater reports of anxiety experience in the HTSA versus the LTSA participants, autonomic measures showed comparable reactivity, habituation, and recovery in the two anxiety groups. These results suggest minimal autonomic differences between HTSA and LTSA individuals, thus supporting theories of social anxiety that emphasize cognitive factors.
The cultural swirl: anthropological perspectives on innovation
Authors: Welz Gisela
Published: June 2003

AbstractAs the emergence of a globalized economy transforms the conditions under which economic performance and productivity growth occur, the ability to innovate has come to the fore as the key factor determining the competitive advantage of national economies, entire industries and individual firms alike. Linking the economic concern with the new products and services to more general questions of the social organization of culture, this essay sets out to explore the contribution of anthropology to an understanding of how innovation occurs. Against the backdrop of theories of cultural change and the identification of parameters that define innovative environments, anthropology enquires into how historical contingency and social agency make innovation possible. In‐depth ethnographic studies emphasize that innovation is much less dependent on the creative individual than on the interaction within social milieux that create what anthropologist Ulf Hannerz calls a ‘cultural swirl’. Such milieux appear to function best when they incorporate heterogeneous actors and are not closed systems but exposed to serendipitous encounters and exchanges with others actors and milieux.
Stillborn chrysalis: reflections on the fate of national culture in neoliberal Zambia
Authors: Ferguson James
Published: June 2003

Abstract In this article I use the analysis of a Zambian on‐line magazine to explore the problems and limits of nationalism in neoliberal times. The magazine, Chrysalis, was a bold attempt by a group of young, educated, cosmopolitan elites to craft a new Zambian nationalism for the information age. The discussions that unfolded in the magazine illustrate some of the difficulties in creating national culture and nationalist discourses of legitimation under conditions of neoliberalism.
Mediated management of meaning: on‐line nation building in Malaysia
Authors: Uimonen Paula
Published: June 2003

Abstract In Malaysia, the Internet figures prominently in the imagery of modernity. Associated with a high‐tech future where the country is positioned in the midst of regional and global flows, the Internet represents the way forward. The Malaysian middle classes are at the forefront of this process of social transformation, their wired lifestyles serving as a model for society. Having readily adapted the Internet, the middle classes have been acculturated in the global culture of networking that it denotes. Their exposure to the world at large has heightened their sense of national identity. Meanwhile, their experience in decentralized interaction has provided them with the means to participate in the construction and reconstruction of national imageries. A medium for on‐line nation building, the Internet has evolved into a machinery of meaning that allows Malaysians to participate in the cultural management of their nation.
Armenians of Athens and Istanbul: the Armenian diaspora and the ‘transnational’ nation
Authors: Björklund Ulf
Published: June 2003

AbstractIn this article I suggest that the ethnographic study of diasporas is one feasible way of mapping and accounting for ongoing realignments of community and identity in the emerging global ecumene. Partly based on ethnographic fieldwork, two widely different sub‐communities of the Armenian diaspora are sketched and compared, those of Athens and Istanbul. I am concerned to show that what looks like multicultural hybridization, at the local level of many cities, can simultaneously and from the diapora point of view take the shape of diasporic and pan‐diasporic mobilization for national goals. The extent to which this happens has much to do with the quality of the basic diasporic myths.
Fields, networks and frames: advertising social organization in Japan
Authors: Moeran Brian
Published: June 2003

Abstract In this article I focus on three kinds of overlapping social coordinates — fields, networks and frames — as they are worked out in the day‐to‐day activities of a large Tokyo advertising agency. My aims are threefold. First, to show how the three social forms of fields, networks and frames interlock in a dialectical manner that permits both macro‐ and micro‐levels of sociological analysis. I thus present methodological approaches hitherto perceived to be different in emphases or interests as complementary rather than at odds with one another. Second, I take up and reexamine the notions of network and frame as developed within the specific context of Japanese social organization. Third, I make a statement in favour of anthropological studies of business as a means of understanding how industries and organizations function in a global economy.
Manchester on my mind: a memoir
Authors: Hart Keith
Published: June 2003

Abstract The author describes his intellectual journey in ten episodes, starting from his upbringing in Manchester and training in Cambridge. After pioneering research in Africa and work as a development advisor, he returned to Manchester as a teacher of social anthropology. Subsequently he spent periods in North America and the Caribbean, before returning to Cambridge for 15 years. He is currently trying to establish himself as a writer in Paris. What follows is neither social science nor autobiography, but a personal account of being in the world in which he tries to move, without discordance, along the whole length of the continuum linking the self to the rest of humanity. The star of the show, however, is Manchester, where his story begins.
Work Incentives under a New Tax System: The Distribution of Effective Marginal Tax Rates in 2002
Authors: Beer Gillian
Published: June 2003

Effective marginal tax rates (EMTRs) provide a way of measuring the balance between targeting of welfare payments and the financial incentive to work. High EMTRs result from income tests for welfare payments overlapping with each other and/or the income tax system.

Individuals who face high EMTRs over broad ranges of income have little financial incentive to increase their earned income. This paper examines the distribution of EMTRs across the Australian labour force in 2002. It also looks at how the number of people facing high EMTRs has changed since the introduction of the new tax system.
Human Capital and Economic Growth: Cross‐Section Evidence for OECD Countries
Authors: Engelbrecht Hans‐Jürgen
Published: June 2003

This paper explores the applicability of the Nelson‐Phelps approach to the modelling of human capital in economic growth for the sample of OECD countries. A case is made for confining the approach to the technology diffusion component and for combining it with the Lucas approach. For such a hybrid model, both the favoured interpretation of the Nelson‐Phelps approach, as well as the Lucas approach, are supported by the evidence. The sensitivity of the findings is assessed with regard to the use of alternative human capital data sets, including quality (adjusted) measures, and with regard to data outliers.
Conjuctive Use of Groundwater and Surface Water in the Burdekin Delta Area
Authors: Hafi Ahmed
Published: June 2003

One of the key economic issues faced by the managers of the two water boards in the Burdekin River Delta is the allocation of surface water between immediate use on farm for irrigation and storage in the aquifer for future use. Because of the significance of the interaction between surface water and groundwater and the return flow externalities within the delta, policies on surface water and groundwater need to be determined simultaneously. A model is formulated of the dynamic system of surface water and groundwater in the delta with water demand, groundwater extraction cost and stochastic recharge and surface water availability. The optimal pumping/artificial recharge policies for each state of the joint surface water and groundwater system is derived for the southern part of the delta and this policy is applied over a large number of years to derive the expected development over time of extraction/artificial recharge and the state of the groundwater system. The implications of the optimal pumping/artificial recharge policy for any review of existing allocations of surface water and groundwater are discussed.
Public Education or Vouchers? The Importance of Heterogeneous Preferences
Authors: Preston Robb
Published: June 2003

This paper looks at the impact heterogeneous preferences for education have on education funding under private, public and voucher systems. An overlapping generations model incorporating human capital is used, where parents are the decision‐makers. They determine their labour supply and their child's education – either directly with personal contributions or collectively by voting on taxes.

The education systems are compared by their impact on the growth and distribution of human capital. The use of heterogenous preferences proves to be critical, as these comparisons differ markedly from the homogenous case.
Valuing the Protection of Aboriginal Cultural Heritage Sites
Authors: Rolfe John , Windle Jill
Published: June 2003

In this paper, a stated value experiment is reported that assesses values held for protecting Aboriginal cultural heritage sites in central Queensland. Choice Modelling, a stated preference non‐market valuation technique, was used to estimate non‐use values for protecting cultural heritage sites in the context of further water resource allocation and irrigation development. Three population groups were sampled, being an indigenous population, and regional centre and capital city populations. Results show that there are significant differences in values between indigenous and general population groups. The general population groups had negative values for high levels of cultural heritage site protection, but did have positive values for small increases in protection above current levels.
Supplying Trade Reform: Political Institutions and Liberalization in Middle‐Income Presidential Democracies
Authors: Nielson Daniel L.
Published: June 2003

Correcting the relative lack of attention to the supply side of trade policy, this article addresses how political institutions channel societal demands for protection. I hypothesize that strong presidents with significant legislative powers and strong party leaders—empowered through electoral rules that rein in the personal vote—can help overcome protectionist biases. These arguments compare with two institutional alternatives: first, that protectionism should decrease as electoral district size grows because elections become more proportional; and second, that the collective‐action problems in fragmented party systems thwart trade reform. I evaluate these hypotheses empirically using pooled time‐series–cross‐sectional data involving 18 developing countries from 1971 to 1997. I find that delegation to presidents and party leaders is significantly related to trade liberalization, and some evidence suggests that the effective number of parties and the size of electoral districts may also influence levels of protectionism.
Policy Transfer as a Form of Prospective Policy Evaluation: Challenges and Recommendations
Authors: Mossberger Karen , Wolman Harold
Published: June 2003

This article focuses on policy transfer as a form of prospective policy analysis, which we define as policy makers' attempts to assess the effect of a policy or program before it is put in place. Despite a burgeoning literature on cross‐national policy transfer, there has been little systematic comparison of cases to identify either common problems or potential strategies in the practice of policy transfer. This article sets forth a rational model of policy transfer and examines, in light of that model, case studies of cross‐national policy transfer spanning different policy domains. Taking into account the constraints faced by policy makers, we relax standard rational decision‐making criteria and make recommendations for improving the process of policy transfer as a form of prospective policy evaluation.
Challenges and Opportunities Facing Nonprofit Organizations
Authors: Brooks Arthur C.
Published: June 2003

Books reviewed in this article:

Lester M. Salamon (ed.), The State of Nonprofit America

Peter Frumkin, On Being Nonprofit: A Conceptual and Policy Primer

Paul C. Light, Pathways to Nonprofit Excellence
Molecular dissection of the inward rectifier potassium current (IK1) in rabbit cardiomyocytes: evidence for heteromeric co‐assembly of Kir2.1 and Kir2.2
Authors: Zobel Carsten , Cho Hee Cheol , Nguyen The‐Tin , Pekhletski Roman , Diaz Roberto J. , Wilson Gregory J. , Backx Peter H.
Published: June 2003

Cardiac inward rectifier K+ currents (IK1) play an important role in maintaining resting membrane potential and contribute to late phase repolarization. Members of the Kir2.x channel family appear to encode for IK1. The purpose of this study was to determine the molecular composition of cardiac IK1 in rabbit ventricle. Western blots revealed that Kir2.1 and Kir2.2, but not Kir2.3, are expressed in rabbit ventricle. Culturing rabbit myocytes resulted in a ∼50 % reduction of IK1 density after 48 or 72 h in culture which was associated with an 80 % reduction in Kir2.1, but no change in Kir2.2, protein expression. Dominant‐negative (DN) constructs of Kir2.1, Kir2.2 and Kir2.3 were generated and tested in tsA201 cells. Adenovirus‐mediated over‐expression of Kir2.1dn, Kir2.2dn or Kir2.1dn plus Kir2.2dn in cultured rabbit ventricular myocytes reduced IK1 density equally by 70 % 72 h post‐infection, while AdKir2.3dn had no effect, compared to green fluorescent protein (GFP)‐infected myocytes. Previous studies indicate that the [Ba2+] required for half‐maximum block (IC50) differs significantly between Kir2.1, Kir2.2 and Kir2.3 channels. The dependence of IK1 on [Ba2+] revealed a single binding isotherm which did not change with time in culture. The IC50 for block of IK1 was also unaffected by expression of the different DN genes after 72 h in culture. Taken together, these results demonstrate functional expression of Kir2.1 and Kir2.2 in rabbit ventricular myocytes and suggest that macroscopic IK1 is predominantly composed of Kir2.1 and Kir2.2 heterotetramers.
The TTX‐Resistant Sodium Channel Nav1.8 (SNS/PN3): Expression and Correlation with Membrane Properties in Rat Nociceptive Primary Afferent Neurons
Authors: Djouhri Laiche , Fang Xin , Okuse Kenji , Wood John N. , Berry Carol M. , Lawson Sally N.
Published: June 2003

We have examined the distribution of the sensory neuron‐specific Na+ channel Nav1.8 (SNS/PN3) in nociceptive and non‐nociceptive dorsal root ganglion (DRG) neurons and whether its distribution is related to neuronal membrane properties. Nav1.8‐like immunoreactivity (Nav1.8‐LI) was examined with an affinity purified polyclonal antiserum (SNS11) in rat DRG neurons that were classified according to sensory receptive properties and by conduction velocity (CV) as C‐, Aδ‐ or Aα/β. A significantly higher proportion of nociceptive than low threshold mechanoreceptive (LTM) neurons showed Nav1.8‐LI, and nociceptive neurons had significantly more intense immunoreactivity in their somata than LTM neurons. Results showed that 89, 93 and 60 % of C‐, Aδ‐ and Aα/β‐fibre nociceptive units respectively and 88 % of C‐unresponsive units were positive. C‐unresponsive units had electrical membrane properties similar to C‐nociceptors and were considered to be nociceptive‐type neurons. Weak positive Nav1.8‐LI was also present in some LTM units including a C LTM, all Aδ LTM units (D hair), about 10 % of cutaneous LTM Aα/β‐units, but no muscle spindle afferent units. Nav1.8‐LI intensity was negatively correlated with soma size (all neurons) and with dorsal root CVs in A‐ but not C‐fibre neurons. Nav1.8‐LI intensity was positively correlated with action potential (AP) duration (both rise and fall time) in A‐fibre neurons and with AP rise time only in positive C‐fibre neurons. It was also positively correlated with AP overshoot in positive neurons. Thus high levels of Nav1.8 protein may contribute to the longer AP durations (especially in A‐fibre neurons) and larger AP overshoots that are typical of nociceptors.
Inspiration‐Promoting Vagal Reflex in Anaesthetized Rabbits after Rostral Dorsolateral Pons Lesions
Authors: Takano Kazuo , Kato Fusao
Published: June 2003

The centrally generated respiratory rhythm is under strong modulation by peripheral information, such as that from the slowly adapting pulmonary stretch receptors (SA‐PSRs) conveyed via the vagus nerve. We have already demonstrated that vagal afferent stimulation at a low frequency (5–40 Hz), or holding the lung volume at the end‐expiratory level (no‐inflation test) prevents spontaneous termination of the inspiratory (I) phase or initiates I activity in anaesthetized rabbits in which the NMDA receptors (NMDA‐Rs) are pharmacologically blocked. Here we show that this I‐promoting vagal reflex also becomes manifest in animals where the pontine respiratory groups are ablated. Following lesions of the rostral dorsolateral pons, including the nucleus parabrachialis medialis and Kölliker‐Fuse nucleus, with radio‐frequency current or local injection of kainic acid, low‐frequency stimulation of the vagus nerve and the no‐inflation test significantly prolonged the I phase in a manner highly similar to that observed in rabbits with NMDA‐R block. Brief stimuli at low frequency during the mid‐expiratory (E) phase evoked I discharge with a latency significantly smaller and less variable than that before the lesions. It is concluded that low‐frequency input from the SA‐PSR suppresses I‐to‐E phase transition and promotes central I activity when the medullary respiratory network is released from pontine influence, which involves NMDA‐R‐mediated signalling.
Contractions Activate Hormone‐Sensitive Lipase in Rat Muscle by Protein Kinase C and Mitogen‐Activated Protein Kinase
Authors: Donsmark Morten , Langfort Jozef , Holm Cecilia , Ploug Thorkil , Galbo Henrik
Published: June 2003

Intramuscular triacylglycerol is an important energy store and is also related to insulin resistance. The mobilization of fatty acids from this pool is probably regulated by hormone‐sensitive lipase (HSL), which has recently been shown to exist in muscle and to be activated by both adrenaline and contractions. Adrenaline acts via cAMP‐dependent protein kinase (PKA). The signalling mediating the effect of contractions is unknown and was explored in this study. Incubated soleus muscles from 70 g male rats were electrically stimulated to perform repeated tetanic contractions for 5 min. The contraction‐induced activation of HSL was abolished by the protein kinase C (PKC) inhibitors bisindolylmaleimide I and calphostin C and reduced 50 % by the mitogen‐activated protein kinase kinase (MEK) inhibitor U0126, which also completely blocked extracellular signal‐regulated kinase (ERK) 1 and 2 phosphorylation. None of the inhibitors reduced adrenaline‐induced HSL activation in soleus muscle. Both phorbol‐12‐myristate‐13‐acetate (PMA), which activates PKC and, in turn, ERK, and caffeine, which increases intracellular Ca2+ without eliciting contraction, increased HSL activity. Activated ERK increased HSL activity in supernatant from basal but not from electrically stimulated muscle. In conclusion, in muscle, PKC can stimulate HSL through ERK. Contractions and adrenaline enhance muscle HSL activity by different signalling mechanisms. The effect of contractions is mediated by PKC, at least partly via the ERK pathway.
Interplay between Nitric Oxide and Vasoactive Intestinal Polypeptide in Inducing Fluid Secretion in Rat Jejunum
Authors: Mourad F. H. , Barada K. A. , Abdel‐Malak N. , Rached N. A. Bou , Khoury C. I. , Saadé N. E. , Nassar C. F.
Published: June 2003

Nitric oxide (NO) and vasoactive intestinal polypeptide (VIP) interact in the regulation of neuromuscular function in the gut. They are also potent intestinal secretogogues that coexist in the enteric nervous system. The aims of this study were: (1) to investigate the interaction between NO and VIP in inducing fluid secretion in the rat jejunum, and (2) to determine whether the NO effect on intestinal fluid movement is neurally mediated. The single pass perfusion technique was used to study fluid movement in a 25 cm segment of rat jejunum in vivo. A solution containing 20 mml‐arginine, a NO precursor, was perfused into the segment. The effect of the NO synthase inhibitors (l‐NAME and l‐nitroindazole (l‐NI)) and the VIP antagonist ([4Cl‐D‐Phe6,Leu17]VIP (VIPa)) on l‐arginine‐induced changes in fluid movement, expressed as μl min−1 (g dry intestinal weight)−1, was determined. In addition, the effect of neuronal blockade by tetrodotoxin (TTX) and ablation of the myenteric plexus by benzalkonium chloride (BAC) was studied. In parallel groups of rats, the effect of l‐NAME and l‐NI on VIP‐induced intestinal fluid secretion was also examined. Basal fluid absorption in control rats was (median (interquartile range)) 65 (45–78). l‐Arginine induced a significant fluid secretion (−14 (−20 to −5); P < 0.01). This effect was reversed completely by l‐NAME (60 (36–65); P < 0.01) and l‐NI (46 (39–75); P < 0.01) and partially by VIPa (37 (14–47); P < 0.01). TTX and BAC partially inhibited the effect of l‐arginine (22 (15–32) and 15 (10–26), respectively; P < 0.05). The effect of VIP on fluid movement (−23 (−26 to −14)) was partially reversed by l‐NAME (24 (8.4–35.5); P < 0.01) and l‐NI (29 (4–44); P < 0.01). The inhibition of VIP or NO synthase prevented l‐arginine‐ and VIP‐induced intestinal fluid secretion through a neural mechanism. The data suggest that NO enhances the release of VIP from nerve terminals and vice versa. Subsequently, each potentiates the other's effect in inducing intestinal fluid secretion.
Transient and sustained types of long‐term potentiation in the CA1 area of the rat hippocampus
Authors: Volianskis Arturas , Jensen Morten S.
Published: June 2003

Synaptic potentiation induced by high frequency stimulation was investigated by recording field excitatory postsynaptic potentials (f‐EPSPs) in rat hippocampal slices. Potentiation consisted of a transient period of decaying f‐EPSPs (short‐term potentiation, STP) that led to a plateau of continuously potentiated f‐EPSPs (long‐term potentiation, LTP). Here we show that a previously unknown type of transient, use‐dependent, long‐lasting potentiation (t‐LTP) can account for STP. t‐LTP could be stored for more than 6 h and its decay was caused by synaptic activation. Both the expression and the decay of t‐LTP were input specific. t‐LTP was induced differently from conventional LTP in that the amplitude of t‐LTP was dependent upon the stimulation frequency, whereas the magnitude of LTP was dependent on the number of stimuli in the induction train. The decay of t‐LTP could not be prevented by the blockage of glutamate receptors, but was prevented by the blockage of stimulus‐evoked neurotransmitter release, suggesting that t‐LTP is expressed presynaptically. Paired‐pulse stimulation experiments showed that the decay of t‐LTP was mediated by a decrease in the probability of neurotransmitter release. The decline of t‐LTP could be prolonged by the activation of NMDA receptors. Hence, both single and paired‐pulse stimuli prolonged the decline of the t‐LTP. This decline could be prevented by high frequency burst stimulation (200 Hz). We conclude that t‐LTP allows dynamic modulation of synaptic transmission by providing not only spatial association but also temporal convergence between synaptic inputs. Therefore, t‐LTP might be a substrate for the encoding of synaptic memory.
IL‐6 Gene Expression in Human Adipose Tissue in Response to Exercise – Effect of Carbohydrate Ingestion
Authors: Keller Charlotte , Keller Pernille , Marshal Sonya , Pedersen Bente Klarlund
Published: June 2003

Interleukin‐6 (IL‐6) is a cytokine involved in a number of immunological processes, but it is also linked to exercise and possibly energy status. During exercise, muscle IL‐6 mRNA levels and plasma IL‐6 levels are increased and further augmented when intramuscular glycogen levels are low. In contrast, the increase in plasma IL‐6 is blunted if carbohydrate is administered, indicating a substrate‐regulated induction of IL‐6 in human skeletal muscle. Recent studies have demonstrated that IL‐6 is also released from adipose tissue in response to an exercise bout. Furthermore, IL‐6 has been demonstrated to have a lipolytic effect, thus possibly playing a role in mobilisation of energy as free fatty acids (FFA) in response to exercise. The purpose of the present study was to investigate the gene expression pattern of IL‐6 in adipose tissue in response to exercise, and to determine whether gene expression was affected by the ingestion of carbohydrate. Eight male subjects performed 3 h of bicycling with ingestion of a carbohydrate drink or placebo. Fat biopsy samples and blood samples were obtained before, during and in the recovery phase of exercise. Both plasma IL‐6 and adipose IL‐6 mRNA levels increased in response to exercise. IL‐6 gene expression was lower (P < 0.05) in the CHO trial (1.98‐fold increase, confidence interval (CI) 1.16–3.83) compared with the control (6.49‐fold increase, CI 3.57–13.91) at end of exercise. Furthermore, CHO ingestion blunted the increase in plasma IL‐6 levels (P < 0.05) at end of exercise (26.0 ± 3.7 pg ml−1 in the control vs. 15.6 ± 2.4 pg ml−1 in the CHO trial). In conclusion, exercise results in an increase in IL‐6 gene expression in adipose tissue in response to exercise, an effect that is significantly blunted by ingestion of carbohydrate.
Morphology and Composition of the Surface of Mars: Mars Odyssey THEMIS Results
Authors: Christensen Philip R. , Bandfield Joshua L. , Bell III James F. , Gorelick Noel , Hamilton Victoria E. , Ivanov Anton , Jakosky Bruce M. , Kieffer Hugh H. , Lane Melissa D. , Malin Michael C. , McConnochie Timothy , McEwen Alfred S. , McSween Harry Y. , Mehall Greg L. , Moersch Jeffery E. , Nealson Kenneth H. , Rice James W. , Richardson Mark I. , Ruff Steven W. , Smith Michael D. , Titus Timothy N. , Wyatt Michael B.
Published: June 2003

The Thermal Emission Imaging System (THEMIS) on Mars Odyssey has produced infrared to visible wavelength images of the martian surface that show lithologically distinct layers with variable thickness, implying temporal changes in the processes or environments during or after their formation. Kilometer-scale exposures of bedrockare observed; elsewhere airfall dust completely mantles the surface over thousands of square kilometers. Mars has compositional variations at 100-meter scales, for example, an exposure of olivine-rich basalt in the walls of Ganges Chasma. Thermally distinct ejecta facies occur around some craters with variations associated with crater age. Polar observations have identified temporal patches of water frost in the north polar cap. No thermal signatures associated with endogenic heat sources have been identified.
Myosin V Walks Hand-Over-Hand: Single Fluorophore Imaging with 1.5-nm Localization
Authors: Yildiz Ahmet , Forkey Joseph N. , McKinney Sean A. , Ha Taekjip , Goldman Yale E. , Selvin Paul R.
Published: June 2003

Myosin V is a dimeric molecular motor that moves processively on actin, with the center of mass moving ∼37 nanometers for each adenosine triphosphate hydrolyzed. We have labeled myosin V with a single fluorophore at different positions in the light-chain domain and measured the step size with a standard deviation of <1.5 nanometers, with 0.5-second temporal resolution, and observation times of minutes. The step size alternates between 37 + 2x nm and 37 – 2x, where x is the distance along the direction of motion between the dye and the midpoint between the two heads. These results strongly support a hand-over-hand model of motility, not an inchworm model.
Activation of Tumor Antigen-Specific Cytotoxic T Lymphocytes (CTLs) by Human Dendritic Cells Infected with an Attenuated Influenza A Virus Expressing a CTL Epitope Derived from the HER-2/neu Proto-Oncogene
Authors: Efferson Clay L. , Schickli Jeanne , Ko Byung Kyum , Kawano Kouichiro , Mouzi Sara , Palese Peter , García-Sastre Adolfo , Ioannides Constantin G.
Published: June 2003

The development of cancer vaccines requires approaches to induce expansion and functional differentiation of tumor antigen-specific cytotoxic T lymphocyte (CTL) effectors which posses cytolytic capability and produce cytokines. Efficient induction of such cells is hindered by the poor immunogenicity of tumor antigens and by the poor transduction efficiency of dendritic cells (DCs) with current nonreplicating vectors. We have investigated the use of influenza A virus, a potent viral inducer of CTLs, as a vector expressing the immunodominant HER-2 CTL epitope KIF (E75). For this purpose, an attenuated influenza A/PR8/34 virus with a truncated nonstructural (NS1) gene was generated containing the E75 epitope in its neuraminidase protein (KIF-NS virus). Stimulation of peripheral blood mononuclear cells from healthy donors and of tumor-associated lymphocytes from ovarian and breast cancer patients with DCs infected with KIF-NS virus (KIF-NS DC) induced CTLs that specifically recognized the peptide KIF and HER-2-expressing tumors in cytotoxicity assays and secreted gamma interferon (IFN-γ) and interleukin-2 at recall with peptide. Priming with KIF-NS DCs increased the number of E75+CD45RO+cells by more than 10-fold compared to nonstimulated cells. In addition, KIF-NS virus induced high levels of IFN-α in DCs. This is the first report demonstrating induction of human epitope-specific CTLs against a tumor-associated antigen with a live attenuated recombinant influenza virus vector. Such vectors may provide a novel approach for tumor antigen delivery, lymphocyte activation, and differentiation in human cancer vaccine development.
Extracellular metalloproteinases inPhytomonas serpens
Authors: Vermelho Alane B , Almeida Flávia V.S , Bronzato Leandro S , Branquinha Marta H
Published: June 2003

The detection of extracellular proteinases in Phytomonas serpens, a trypanosomatid isolated from tomato fruits, is demonstrated in this paper. Maximal production occurred at the end of the logarithmic phase of growth. These enzymes exhibited selective substrate utilization in SDSPAGE, being more active with gelatin; hemoglobin and bovine serum albumin were not degraded. Three proteinases were detected in SDSPAGE-gelatin, with apparent molecular masses between 94 and 70 kDa. The proteolytic activity was completely blocked by 1,10-phenanthroline and strongly inhibited by EDTA, whereas a partial inhibition was observed with trans-epoxysuccinyl-L-leucylamido-(4-guanidino) butane and soybean trypsin inhibitor; phenylmethylsulfonyl fluoride weakly inhibited the enzymes. This inhibition profile indicated that these extracellular proteinases belong to the metalloproteinase class. Key words: trypanosomatids, metalloproteinases, tomatoes, Phytomonas.
ORF98 ofAutographa californicanucleopolyhedrosisvirusis an auxiliary factor in late gene expression
Authors: Hefferon Kathleen L
Published: June 2003

Autographa californica nucleopolyhedrosisvirus (AcMNPV) is the type member of the family Baculoviridae. Gene expression of AcMNPV during virus infection is temporally regulated. A series of late expression factors (LEFs) are required for late gene expression to take place. A number of additional factors have also been shown to more modestly influence late gene expression. Using the LEF transient assay, we scanned the AcMNPV genome for such factors by replacing plasmids using the LEF genes with larger clones and then looked for increases in late gene expression using a reporter plasmid under the control of a late promoter. Using this approach, ORF98 was identified as having a stimulatory effect on late gene expression. The ability of ORF98 to influence early, late, and very late gene expression was established. Furthermore, tagged versions of ORF98 were localized to the nuclei of transfected cells and were shown to interact with each other as homo-oligomers. Potential roles of ORF98 in baculovirus infection are discussed.Key words: AcMNPV, late expression factors, transactivator, gene expression.
Interaction of secretory immunoglobulin A antibodies withNaegleria fowleritrophozoites and collagen type I
Authors: Shibayama Mineko , Serrano-Luna José de Jesús , Rojas-Hernández Saúl , Campos-Rodríguez Rafael , Tsutsumi Víctor
Published: June 2003

In this work, we analyzed the in vitro interaction of human secretory immunoglobulin A (sIgA) antibodies with Naegleria fowleri trophozoites and the capacity of these antibodies to inhibit amoeba adherence to collagen type I. We also studied N. fowleri antigens that are recognized by sIgA, using immunoblot assays. Immunocytochemical analysis of the interaction showed a redistribution of antigens on the surface of trophozoites by sIgA antibodies. Ultrastructural analysis of antibodyamoeba interaction showed that besides the patching and cap formation, parasites were capable of eliminating the antigenantibody complex produced on the surface. sIgA antibodies were capable of inhibiting the in vitro adhesion of trophozoites to collagen type I. We suggest that nonsymptomatic infections by N. fowleri may stimulate a local specific immunity that prevents trophozoite adhesion and invasion of nasal mucosa.Key words: Naegleria fowleri, free-living amoebae, human antibodies, secretory IgA, mucosal immunity.
Characteristics of a cluster of xylanase genes inFibrobacter succinogenesS85
Authors: Jun Hyun S , Ha Jong K , Malburg, Jr. Laercio M , Verrinder Gibbins Ann M , Forsberg Cecil W
Published: June 2003

Xylanase genes xyn10D, xyn10E, and xyn10B, located sequentially on the Fibrobacter succinogenes S85 chromosome, were separately cloned and their properties characterized. Analysis of the sequences documented that xylanases Xyn10D, Xyn10E, and Xyn10B each consist of an N-terminal catalytic domain (glycosyl hydrolase family 10) and a C-terminal carbohydrate-binding module (CBM, family 6) connected by proline-rich linker sequences. The amino acid sequences exhibited similarities of between 53 and 60%. The xyn10D, xyn10E, and truncated xyn10BΔCBM were expressed in Escherichia coli and purified to homogeneity. The purified Xyn10D, Xyn10E, and Xyn10BΔCBM exhibited the same temperature optimum (40°C) and pH optimum (6.5) and the highest specific activity against arabinoxylan, oat spelt xylan, and birchwood xylan, respectively. Xyn10D exhibited an affinity for cellulose and xylan with 47 and 33% binding, respectively, while the truncated Xyn10DΔCBM did not bind to the substrates. The main hydrolysis products of the three xylanases acting on oat spelt xylan and arabinoxylan were xylose and xylobiose. RT-PCR analysis showed that the three genes were co-transcribed as a single transcript. Western immunoblot analysis revealed that the three xylanases were expressed at a very low level by F. succinogenes grown on either glucose or cellulose as the source of carbohydrate.Key words: Fibrobacter succinogenes S85, xylan, xylanase, clustered genes, RT-PCR.
Blocking ofPseudomonas aeruginosalectins by human milk glycans
Authors: Lesman-Movshovich Efrat , Lerrer Batia , Gilboa-Garber Nechama
Published: June 2003

The opportunistic human pathogen Pseudomonas aeruginosa produces a D-galactophilic (PA-IL) lectin and another lectin (PA-IIL) that binds L-fucose > D-arabinose > D-mannose in close association with its host-attacking factors. These lectins contribute to the virulence of P. aeruginosa by their involvement in the production, adhesion, and pathogenic effects of its biofilm on host cells. Therefore, they are considered targets for anti-Pseudomonas therapy. The present study compares their blocking by human milk samples with that of the plant lectin Con A. It demonstrates that human milk inhibits the hemagglutinating activities of the three lectins, with PA-IIL much more strongly inhibited than PA-IL or Con A. Using these lectins, Western blots of the milk samples accord with the hemagglutination inhibition data and disclose the distribution of the human milk glycoproteins that inhibit each lectin. The data of this paper reveal the high efficiency of human milk components in blocking the P. aeruginosa lectins and the usefulness of these lectins for detecting milk glycoprotein saccharides, which may protect the infant against infections.Key words: Pseudomonas aeruginosa, lectins, human milk, glycoproteins, Western blotting.
Nitrate reductase from the magnetotactic bacteriumMagnetospirillum magnetotacticumMS-1: purification and sequence analyses
Authors: Taoka Azuma , Yoshimatsu Katsuhiko , Kanemori Masaaki , Fukumori Yoshihiro
Published: June 2003

We purified the nitrate reductase from the soluble fraction of Magnetospirillum magnetotacticum MS-1. The enzyme was composed of 86- and 17-kDa subunits and contained molybdenum, non-heme iron, and heme c. These properties are very similar to those of the periplasmic nitrate reductase found in Paracoccus pantotrophus. The M. magnetotacticum nap locus was clustered in seven open reading frames, napFDAGHBC. The phylogenetic analyses of NapA, NapB, and NapC suggested a close relationship between M. magnetotacticum nap genes and Escherichia coli nap genes, which is not consistent with the 16S rDNA data. This is the first finding that the α subclass of Proteobacteria possesses a napFDAGHBC-type nap gene cluster. The nap gene cluster had putative fumarate and nitrate reduction regulatory protein (Fnr) and NarL protein binding sites. Furthermore, we investigated the effect of molybdate deficiency in medium on the total iron content of the magnetosome fraction and discussed the physiological function of nitrate reductase in relation to the magnetite synthesis in M. magnetotacticum.Key words: nitrate reductase, magnetotactic bacteria, denitrification, horizontal gene transfer.
Stimulation of the cyanide-resistant alternative respiratory pathway by oxygen inAcremonium chrysogenumcorrelates with the size of the intracellular peroxide pool
Authors: Karaffa Levente , Sándor Erzsébet , Fekete Erzsébet , Kozma József , Szentirmai Attila , Pócsi István
Published: June 2003

The relationship between oxygen input and activity of the cyanide-resistant alternative respiration of submerged cultures of Acremonium crysogenum was investigated. The volumetric oxygen transfer coefficient of the respective cultures correlated positively within almost two ranges of magnitude with the size of the intracellular peroxide pool, which in turn, correlated with the activity of the cyanide-resistant alternative respiratory pathway. Increased aeration also stimulated the glucose uptake rate but had no effect on the total respiration rate or the growth rate. Addition of the lipid peroxyl radical scavenger DL-α-tocopherol to A. chrysogenum cultures decreased the rate of intracellular peroxide production as well as glucose uptake. An increase in the cyanide-resistant fraction of total respiration was observed, while growth and the total respiratory activity remained unchanged. We conclude that intracellular peroxides may stimulate the alternative respiration in A. chrysogenum.Key words: Acremonium chrysogenum, alternative respiration, oxygen, peroxide, Kla.