bluuebunny/crossref_metadata_2025 huggingface dataset:
Flow‐dependent resistance of nasal masks used for non‐invasive positive pressure ventilation
Authors: WINDISCH Wolfram , BUCHHOLT Alexander , STAHL Claudius A. , SORICHTER Stephan , GUTTMANN Josef
Published: May 2006

Objective and background:  Endotracheal tube resistance is known to be flow‐dependent and this understanding has improved the application of invasive ventilation. However, similar physiological studies on the interface between patients and non‐invasive positive pressure ventilation (NPPV) have not been performed. Therefore, this study was aimed at investigating the resistance of nasal masks used for NPPV.

Methodology:  The flow‐dependent pressure drop of the small (S), medium‐small (MS) and medium (M) Contour Nasal Mask (Respironics Inc., Murrysville, PA, USA) was measured with and without a connecting tube (length 18 cm, internal diameter 1.5 cm) in a laboratory study. The resistance was calculated by Rohrer’s equation using the standard least‐squares‐fit technique. The present study explicitly differentiated between the resistance of the nasal mask alone when measured against atmosphere and the additional resistance caused by the nasal mask when airtightly fitted to a model head (interaction with the face).

Results:  Higher flow rates resulted in a non‐linearly increasing pressure drop across the interface. This flow‐dependent resistance of the S/MS/M mask was comparably low when not interacting with the face, but increased when interacting with the face. This flow‐dependent resistance of the mask was several‐fold higher when adding the connection tube and tended to be higher during expiration.

Conclusion:  There is a non‐linear flow‐dependent pressure drop across the nasal mask which is low and independent of its size, but increases when interacting with the face. The connecting tube is the major determinant of the resistance originating from facial appliances used for NPPV.
Delay period activity of monkey prefrontal neurones during duration‐discrimination task
Authors: Oshio Ken‐ichi , Chiba Atsushi , Inase Masahiko
Published: May 2006

Evidence from brain imaging studies has indicated involvement of the prefrontal cortex (PFC) in time perception; however, the role of this area remains unclear. To address this issue, we recorded single neuronal activity from the PFC of two monkeys while they performed a duration‐discrimination task. In the task, two visual cues (a blue or red square) were presented consecutively followed by delay periods and subjects then chose the cue presented for the longer duration. Durations of both cues, order of cue duration [long–short (LS) or short–long (SL)] and order of cue colour (blue–red or red–blue) were randomized on a trial‐by‐trial basis. We found that subjects responded differently between LS and SL trials and that most prefrontal neurones showed significantly different activity during either the first or the second delay period when comparing activity in LS and SL trials. The present result offers new insights into neural mechanisms of time perception. It appears that, during the delay periods, the PFC contributes to implement a strategic process in temporal processing associated with a trial type (LS or SL) such as representation of the trial type, retention of cue information and anticipation of the forthcoming cue.
Cellular and subcellular localization of neurokinin‐1 and neurokinin‐3 receptors in primate globus pallidus
Authors: Lévesque Martin , Parent Rémy , Parent André
Published: May 2006

The primate globus pallidus receives massive innervations from GABAergic striatal neurons that co‐release the neuropeptide substance P (SP). To expand our knowledge regarding SP interaction at pallidal level, we used single and double antigen retrieval methods to study the cellular and subcellular localization of SP and its high‐affinity receptors neurokinin‐1 (NK‐1R) and neurokinin‐3 (NK‐3R) in the globus pallidus of the squirrel monkey (Saimiri sciureus). At the light microscopic level, a large number of neurons and fibers located in both the external (GPe) and internal (GPi) segments of the globus pallidus expressed NK‐1R or NK‐3R immunoreactivity. At the electron microscopic level, both NK‐1R and NK‐3R were mainly associated with intracellular sites or located at extrasynaptic positions on the plasma membrane. Presynaptic axon terminals forming symmetric and asymmetric synapses occasionally contained NK‐1R and NK‐3R. Neurokinin receptors were also observed in a proportion of SP‐immunoreactive axon terminals, but these terminals preferentially expressed NK‐3R. The pattern of distribution of NK‐1R and NK‐3R in GPe and GPi indicates that SP effects at pallidal level are mediated through postsynaptic receptor as well as presynaptic autoreceptors and heteroreceptors. These morphological data suggest that, either alone or in conjunction with GABA, SP could have a wide range of effects at pallidal level. This neuroactive peptide may influence in a significant manner the integration and treatment of neural information that flows through the basal ganglia.
Further Confusion in the Study of Self‐Regulation: Comments on Cervone, Shadel, Smith, and Fiori
Authors: Locke Edwin A. , Latham Gary P.
Published: May 2006

We applaud Cervone, Shadel, Smith, and Fiori's goal to clarify the self‐regulation literature and to show how intra‐individual personality studies might help do this. Unfortunately, we do not believe the paper achieves its goal. Rather it only confuses matters further. This is due to the lack of clear definitions or explanation of key concepts and theories, false claims about certain personality measures and other issues, confusions about the relation between process and content, the offering as new insights ideas which are, in fact, not new, and the failure to make clear how intra‐individual studies would actually be used.
Aspects of Anglican Identity – Colin Podmore
Authors: Atkins Peter
Published: May 2006

Book reviewed:

Aspects of Anglican Identity, Colin Podmore, Church House Publishing 2005 (0‐7151‐4074‐4), xi + 196 pp., pb £14.99
Ancient Israel, Judaism and Christianity in Contemporary Perspective. Essays in Memory of Karl‐Johan Illman – Edited by Jacob Neusner, Alan J. Avery‐Peck, Antti Laato, Risto Nurmela and Karl Gustav Sandelin (eds)
Authors: Bury Benjamin
Published: May 2006

Book reviewed:

Ancient Israel, Judaism and Christianity in Contemporary Perspective. Essays in Memory of Karl‐Johan Illman, Jacob Neusner, Alan J. Avery‐Peck, Antti Laato, Risto Nurmela and Karl Gustav Sandelin (eds), Lanham University Press of America 2006 (0‐7618‐3362‐5), ix + 448 pp., pb $41.00
Cinéma Divinité: Religion, Theology, and the Bible in Film – Edited by Eric S. Christianson, Peter Francis and William Telford (eds)
Authors: Gravett Sandie
Published: May 2006

Book reviewed:

Cinéma Divinité: Religion, Theology, and the Bible in Film, Eric S. Christianson, Peter Francis and William Telford (eds), SCM press 2005 (0‐334‐02988‐0), xvii + 373 pp., pb £19.99
The Jewish Social Contract: An Essay in Political Theology – David Novak
Authors: Hamilton Mark W.
Published: May 2006

Book reviewed:

The Jewish Social Contract: An Essay in Political Theology, David Novak, Princeton University Press 2005 (0‐691‐12210‐5), xxi + 257 pp., hb $39.50
Philosophy, God and Motion – Simon Oliver
Authors: Ellis‐Killian Sandra
Published: May 2006

Book reviewed:

Philosophy, God and Motion, Simon Oliver, Taylor and Francis 2005 (0‐415‐36045‐5), x + 249 pp., hb $75.00
A Theology of Christian Spirituality – Samuel M. Powell
Authors: Armson John
Published: May 2006

Book reviewed:

A Theology of Christian Spirituality, Samuel M. Powell, Abingdon Press 2005 (0‐687‐49333‐1), vii + 227 pp., pb $26.00/£19.99
In Defense of Natural Theology: A Post‐Humean Assessment – Edited by James F. Sennett and Douglas Groothuis (eds)
Authors: Anderson Owen
Published: May 2006

Book reviewed:

In Defense of Natural Theology: A Post‐Humean Assessment, James F. Sennett and Douglas Groothuis (eds), Intervarsity Press 2005 (0‐8308‐2767‐6), 336 pp., pb $13.00
Loves Me, Loves Me Not: The Ethics of Unrequited Love – Laura A. Smit
Authors: McCarthy David M.
Published: May 2006

Book reviewed:

Loves Me, Loves Me Not: The Ethics of Unrequited Love, Laura A. Smit, BakerAcademic 2005 (0‐8010‐2997‐X), 265 pp., pb $18.99
Harvesting Martin Luther’s Reflections on Theology, Ethics, and the Church – Edited by Timothy J. Wengert (ed.)
Authors: Cross Richard
Published: May 2006

Book reviewed:

Harvesting Martin Luther’s Reflections on Theology, Ethics, and the Church, Timothy J. Wengert (ed.), Lutheran Quarterly Books, William B. Eerdmans Publishing Company 2004 (8‐028‐2486‐2), xiv + 260 pp., £21.99
World without End: Christian Eschatology from a Process Perspective – Edited by Joseph A. Bracken (ed.)
Authors: Reed Esther D.
Published: May 2006

Book reviewed:

World without End: Christian Eschatology from a Process Perspective, Joseph A. Bracken (ed.), Eerdmans 2005 (0‐8028‐2811‐6), ix + 232 pp., hb $30.00/£18.95
A Pilgrim People. Learning through the Church Year – John H. Westerhoff III
Authors: Kalve Peter
Published: May 2006

Book reviewed:

A Pilgrim People. Learning through the Church Year, John H. Westerhoff III, Seabury Classics (Church Publishing Inc.) 2005 (1‐59628‐010‐7), ix + 114 pp., pb $13.00
Adaptation in new technology‐based ventures: Insights at the company level
Authors: Andries Petra , Debackere Koenraad
Published: May 2006

Recent research shows that, owing to the presence of uncertainty and ambiguity, new ventures have great difficulties in defining a viable business model from the outset and that minor or major adaptations to this initial business model are needed as the venture evolves. Technology‐based companies are confronted with particularly high degrees of uncertainty and ambiguity. This paper therefore focuses on new technology‐based ventures as a special case worth investigating. Most of the entrepreneurship literature studies adaptation at the individual level. However, many new technology‐based firms are founded by a team of entrepreneurs. This paper therefore looks at how existing literature at the company level can inform us about adaptation in new technology‐based companies. It starts by relating the concept of adaptation in new technology‐based ventures to the existing literature on organizational adaptation at the firm level. Based on an overview of existing literature at the firm level, a propositional model is then put forward, describing (1) the process of adaptation and (2) the factors enabling adaptation in new technology‐based ventures.
The European‐Specific Mitochondrial Cluster J/T Could Confer an Increased Risk of Insulin‐Resistance and Type 2 Diabetes: An Analysis of the m.4216T > C and m.4917A > G Variants
Authors: Crispim D. , Canani L. H. , Gross J. L. , Tschiedel B. , Souto K. E. P. , Roisenberg I.
Published: May 2006

The aims of this study were to investigate the contributions of the mitochondrial DNA m.4216T > C and m.4917A > G variants, and also of the European‐specific mitochondrial cluster J/T, to the development of type 2 diabetes mellitus in Caucasian‐Brazilian patients from Southern Brazil. We analyzed 347 type 2 diabetes patients and 350 control subjects. Variant frequencies in patients and control subjects were compared using χ2 tests or odds ratio. We also compared clinical and laboratory characteristics among patients with and without the variants. We found that the frequencies of the m.4216T > C and m.4917A > G variants are higher in diabetic patients than in control subjects. Moreover, haplogroups J (partially defined by the presence of the m.4216T > C variant only) and T (partially defined by the presence of both m.4216T > C and m.4917A > G variants) are more frequent in the type 2 diabetic group than in the control group. Patients belonging to the cluster J/T are more insulin resistant than patients of other haplogroups. In conclusion, our results indicate the association of the cluster J/T (as suggested by analyses of the m.4216T > C and m.4917A > G variants) with insulin resistance and type 2 diabetes.
Mycorrhizas and soil structure
Authors: Rillig Matthias C. , Mummey Daniel L.
Published: May 2006

In addition to their well‐recognized roles in plant nutrition and communities, mycorrhizas can influence the key ecosystem process of soil aggregation. Here we review the contribution of mycorrhizas, mostly focused on arbuscular mycorrhizal fungi (AMF), to soil structure at various hierarchical levels: plant community; individual root; and the soil mycelium. There are a suite of mechanisms by which mycorrhizal fungi can influence soil aggregation at each of these various scales. By extension of these mechanisms to the question of fungal diversity, it is recognized that different species or communities of fungi can promote soil aggregation to different degrees. We argue that soil aggregation should be included in a more complete ‘multifunctional’ perspective of mycorrhizal ecology, and that in‐depth understanding of mycorrhizas/soil process relationships will require analyses emphasizing feedbacks between soil structure and mycorrhizas, rather than a uni‐directional approach simply addressing mycorrhizal effects on soils. We finish the discussion by highlighting new tools, developments and foci that will probably be crucial in further understanding mycorrhizal contributions to soil structure.

Contents

Summary
41

I.
Introduction
42

II.
How mycorrhizal fungi can influence soil aggregation at various scales
42

III.
Effects of fungal mycelium: a mechanistic discussion
44

IV.
Role of fungal diversity
48

V.
Emerging foci, new directions and tools
49

VI.
Conclusions
50

Acknowledgements
50

References
50
Hepatitis C and Alcohol
Authors: Regev Arie , Jeffers Lennox J.
Published: May 2006

Background: Alcohol abuse and hepatitis C virus (HCV) infection frequently coexist in patients with chronic liver disease. It is widely believed that alcohol and HCV act synergistically in these patients to promote the development and progression of liver damage.

Methods: A review of the relevant medical literature, identified by computer assisted literature search, was conducted.

Results: It has been established that alcohol consumption is associated with the accelerated progression of liver injury, higher frequency of cirrhosis, and higher incidence of hepatocellular carcinoma. Alcohol abuse is also associated with decreased response to interferon treatment, and there are reports to suggest that patients with HCV cirrhosis, who abuse alcohol, have higher mortality than those who do not. Abstinence may reverse some of these deleterious effects of alcohol, and may even improve the ultimate response to treatment. The mechanism for the synergistic effect of alcohol and HCV is not fully understood, but has been attributed to alcohol's effect on viral replication, or to its effect on the immune system, hepatic iron content, or hepatic regeneration.

Conclusions: Alcohol has a deleterious effect on HCV associated liver disease. It is recommended that patients with HCV infection abstain from alcohol consumption.
Surgical Excision of Primary Canine Rectal Tumors by an Anal Approach in Twenty‐Three Dogs
Authors: DANOVA NICHOLE A. , ROBLES‐EMANUELLI JUAN CARLOS , BJORLING DALE E.
Published: May 2006

Objective— To describe an anal approach for excision of primary rectal tumors in dogs and to report outcome.

Study Design— Retrospective study.

Animals— Dogs (n=23) with primary rectal tumors.

Methods— Review of medical records (1990–2000) of dogs with primary rectal neoplasia excised surgically using an anal approach with rectal prolapse. With dogs anesthetized, the rectum was prolapsed, stabilized with stay sutures during tumor excision with 1 cm margins to the level of the muscularis, then the rectal mucosa was sutured.

Results— Each dog had only 1 tumor type (adenocarcinoma [8], solitary polyp [5], carcinoma [4], plasmacytoma [2], adenoma [1], leiomyoma [1], mucinous carcinoma [1], and papilloma [1]). Mean tumor volume was 3.1 cm3 (range 0.1–37.7 cm3). Postoperative complications (rectal bleeding [5], tenesmus [4]) were mild and resolved within 7 days after surgery; another dog had partial mucosal dehiscence identified at 6 days. The primary tumor was incompletely excised in 1 dog (4.3%), and local recurrence occurred 16 and 24 months after surgery in 2 dogs. Outcome beyond the immediate postoperative period was known for 18 dogs, including 2 dogs still alive. Mean postoperative disease‐free interval for these 18 dogs was 36.8 months (range 5–84 months).

Conclusion— Surgical excision of tumors of the caudal rectum can be accomplished through the anus after rectal prolapse.

Clinical Relevance— An anal approach facilitated by rectal prolapse should be considered as a viable option for the surgical treatment of selected cases of tumors of the caudal aspect of the rectum in dogs.
Perspectives on Risk Perceptions
Authors: Cole Gerald A. , Withey Stephen B.
Published: May 2006

Drawing on the literature from the fields of cognitive and social psychology, sociology, and political science, we discuss perceptions of risks and benefits, the impact of perceptions and personal preferences on choice and behavior, the question of “socially acceptable” thresholds of risk, and the analytic and descriptive means by which such thresholds might be identified. We hypothesize that existing psychometric methods may be adapted for the scaling of perceived benefit. We review factors hampering the application of formal methodologies in the resolution of controversial public debates, and express doubt about the identification of a socially acceptable threshold of risk. We argue that the emphasis of research in this field should be shifted toward explicating the use of risk and benefit perceptions in the process of personal decision‐making. Finally, we suggest several social science research approaches that may be used to address these issues.
Judged Lethality: How Much People Seem to Know Depends Upon How They Are Asked
Authors: Fischhoff Baruch , MacGregor Don
Published: May 2006

Four formally equivalent response modes were used to elicit laypeople's beliefs regarding the lethality of various potential causes of death. Results showed that respondents had an articulated core of beliefs about lethality that yielded similar orderings of maladies by lethality regardless of the response mode used. Moreover, this subjective ordering was fairly similar to that revealed by public health statistics. However, the absolute estimates of lethality produced by the different response modes varied enormously. Depending upon the mode used, respondents were seen to greatly overestimate or greatly underestimate lethality. The implications of these discrepancies for public education and risk analysis are explored.
Patterns of Conflict About Risky Technologies
Authors: Winterfeldt Detlof von , Edwards Ward
Published: May 2006

This paper examines taxonomies for classifying risks and conflicts about risky technologies. First, we describe six levels of conflict that represent various “ shades of gray” between purely factual and purely value laden conflicts in technology disputes. Subsequently, we survey several recent taxonomies of risks and hazards that were at least partly intended to clarify the nature of the public conflicts about technologies and their risks. After pointing out that non‐risk features frequently shape technology debates, we develop a taxonomy of the disputes themselves, based on a collection of 162 cases. Our taxonomy of technological controversies is related to the recent risk taxonomies and to the different levels of conflict. It turns out that the different technological disputes create quite different levels of conflict ranging from mainly factual (consumer products, drugs) to extremely value laden (nuclear power, genetic engineering). Depending on the type of controversy and level of conflict we suggest alternative conflict management strategies.
Improving Scientists’Judgments of Risk
Authors: Hammond Kenneth R. , Anderson Barry F. , Sutherland Jeffrey , Marvin Barbara
Published: May 2006

Scientists disagree in their risk analyses because they use intuitive judgments to generalize results from the laboratory to circumstances not yet studied. If this assertion is correct, techniques intended to reduce intuitive judgments and increase analytical cognition should reduce scientific dispute. The results of a test case involving allegedly high risk and sharp dispute among scientists are described.
SENSORY TEXTURE RELATED TO LARGE‐STRAIN RHEOLOGICAL PROPERTIES OF AGAR/GLYCEROL GELS AS A MODEL FOOD
Authors: BARRANGOU LISA M. , DRAKE MARY ANNE , DAUBERT CHRISTOPHER R. , ALLEN FOEGEDING E.
Published: May 2006

Descriptive sensory analysis and large‐strain rheological methods were used to evaluate textural characteristics of agar gels as a model food. The gels were differentiated in the same manner by sensory analysis and rheological properties (P ≤ 0.05), and significant correlations between sensory and rheological properties were reported. First bite and chew‐down sensory terms correlated with each other and with fracture properties. Specifically, the first bite sensory term “fracture force” correlated with the chew‐down sensory term “chewiness” (r = 0.99,P ≤ 0.001), and both of these sensory terms were correlated with fracture stress (σf) and modulus (r = 0.94 − 0.97,P ≤ 0.05). The first bite sensory term “deformability” was positively correlated with fracture strain (r = 0.88,P ≤ 0.05) and negatively correlated with the strain‐hardening constant (r = −0.93,P ≤ 0.05). The chew‐down property “particle breakdown” was negatively correlated withσfvalues (r = −0.97,P ≤ 0.05). For agar gels, each sensory texture term can be linked with a large‐strain mechanical property.
INFLUENCE OF ENZYMES ON THE TEXTURE OF BROWN PAN BREAD
Authors: GÁMBARO ADRIANA , GIMÉNEZ ANA , ARES GASTÓN , GILARDI VIRGINIA
Published: May 2006

Enzymes are commonly used to improve the textural quality of bread and to extend its shelf life. To study the effect of enzymes on the texture of brown pan bread, four types of bread were industrially manufactured using amylase, xylanase, a mixture of amylase : xylanase (1:1) and control (no enzyme). After baking, the bread samples were stored for 1, 4, 7, 10, 13, 15 and 17 days. At each storage time, bread texture was evaluated by sensory and instrumental methods, and the overall acceptability was determined.

Instrumental and sensory texture data showed that the addition of amylase or amylase : xylanase decreased the staling rate of breads. Furthermore, the use of a mixture of amylase and xylanase provided better results than the addition of amylase alone. Therefore, the results suggest that the addition of a mixture of amylase and xylanase is recommended to extend the shelf life of brown pan bread. On the other hand, the addition of xylanase resulted in an increase of the staling rate. The results suggest that when xylanase is used to improve dough machinability, the addition of amylase along with it should be considered in order to prevent an increase of staling rate.
The Economic Rise of China: Challenges and Opportunities for ASEAN
Authors: CHIA Siow Yue , SUSSANGKARN Chalongphob
Published: May 2006

This paper looks at the economic rise of China and its impacts and implications for the Association of South‐East Asian Nations (ASEAN) region. The issues of complementarities and competitiveness of ASEAN and China in trade and investment and the opportunities and challenges arising from China's emergence and the ASEAN‐China Free Trade Area are discussed. The message from China's emergence is clear and strong; it is that size does matter. To increase ASEAN competitiveness, the paper highlights the need for a deeper and more rapid economic integration of ASEAN in order to exploit scale economies. The important role of Japan in this process is highlighted. Finally the issue of ASEAN economic diversity is discussed. It is suggested that while ASEAN is fairly diverse, this should not be a critical stumbling block to a more rapid economic integration of ASEAN.
Thermal Ignition in a Reactive Viscous Flow Through a Channel Filled With a Porous Medium
Authors: Makinde O. D.
Published: May 2006

This paper examines the steady-state solutions of a strongly exothermic reaction of a viscous combustible material in a channel filled with a saturated porous medium under Arrhenius kinetics, neglecting reactant consumption. The Brinkman model is employed and analytical solutions are constructed for the governing nonlinear boundary-value problem using a perturbation technique together with a special type of Hermite-Padé approximants and important properties of the temperature field including bifurcations and thermal criticality are discussed.
Functional roles of cationic amino acid residues in the sodium-dicarboxylate cotransporter 3 (NaDC-3) from winter flounder
Authors: Hagos Yohannes , Steffgen Jürgen , Rizwan Ahsan N. , Langheit Denis , Knoll Ariane , Burckhardt Gerhard , Burckhardt Birgitta C.
Published: May 2006

In the present study, we determined the functional role of 15 positively charged amino acid residues at or within 1 of the predicted 11 transmembrane helixes of the flounder renal sodium-dicarboxylate cotransporter fNaDC-3. Using site-directed mutagenesis, histidine (H), lysine (K), and arginine (R) residues of fNaDC-3 were replaced by alanine (A), isoleucine (I), or leucine (L). Most mutants showed sodium-dependent, lithium-inhibitable [14C]succinate uptake and, in two-electrode voltage-clamp (TEVC) experiments, Km and Δ Imax values comparable to wild-type (WT) fNaDC-3. The replacement of R109 and R110 by alanine and isoleucine (RR109/110AI) prevented the expression of fNaDC-3 at the plasma membrane. When the lysines at positions 232 and 235 were replaced by isoleucine (KK232/235II), the transporter was expressed but showed small transport rates and succinate-induced currents. K114I, located within transmembrane helix 4, showed [14C]succinate uptake similar to WT but relatively small inward currents. When K114 was replaced by arginine, glutamic acid (E), or glutamine (Q), all mutants were expressed at the cell surface. In [14C]succinate uptake and TEVC experiments performed simultaneously on the same oocytes, uptake was similar to or higher than WT, whereas succinate-induced currents were either comparable (K114R) to, or considerably smaller (K114E, K114I, K114Q) than, those evoked by WT. These results suggest that a positively charged residue at position 114 is required for electrogenic sodium-dicarboxylate cotransport.
Dendritic Projections and Dye-Coupling in Dopaminergic Neurons of the Substantia Nigra Examined in Horizontal Brain Slices From Young Rats
Authors: Lin John Y. , van Wyk Michiel , Bowala Tharushini K. , Teo Min-Yau , Lipski Janusz
Published: May 2006

We examined the rostro-caudal dendritic spread of striatally projecting dopaminergic neurons of the Substantia Nigra pars compacta (SNc) and investigated the presence of dye-coupling after labeling these cells with a mixture of lucifer yellow (LY) and neurobiotin (NB) or with LY alone. Whole cell recordings were made from horizontal brain slices (400 μm) obtained from P5-P20 rats. SNc neurons retrogradely labeled with Fluoro-Gold and located in the region containing tyrosine hydroxylase-immunoreactive cells displayed Ih current and other properties characteristic of SNc neurons. To prevent extracellular leakage, dyes were introduced into patch pipettes after the establishment of whole cell configuration, and cells were filled under visual control. In contrast to previous studies conducted in coronal sections that identified dendritic projections of SNc neurons mainly in the medio-lateral and ventral directions, almost all neurons labeled in our study (53/54) additionally displayed a large rostro-caudal dendritic span (649 ± 219 μm). Dye-coupling between SNc neurons was not observed under basal conditions, in the presence of gap junction “openers” (forskolin, trimethylamine), or after neurons were filled with LY using sharp intracellular microelectrodes. As a “positive control,” dye-coupling was demonstrated in four hippocampal dentate gyrus neurons that were filled using the same patch pipette technique. In addition, none of the tested SNc cells ( n = 12) showed expression of connexin 36 (the “neuronal” connexin) when tested with single-cell RT-PCR. In conclusion, this study revealed extensive rostro-caudal dendritic projections of SNc neurons. Under our in vitro conditions, no evidence was found for dye-coupling among these neurons.
Substance P Evokes Cation Currents Through TRP Channels in HEK293 Cells
Authors: Oh E. J. , Gover T. D. , Cordoba-Rodriguez R. , Weinreich D.
Published: May 2006

Activation of any of the three known tachykinin receptors (NK1R, -2R, or -3R) can cause a rise in [Ca2+]i via a pertussis toxin-insensitive heterotrimeric G protein, Gq/G11, activation of phospholipase C (PLC), and a membrane depolarization. Tachykinins can depolarize neurons by two distinct mechanisms: 1) they reduce a resting K+ current in many neurons or 2) in parasympathetic and vagal primary sensory neurons, they activate a nonspecific cation current ( Icat). Transient receptor potential channels (TRPC) are nonspecific cation channels that can be activated by a rise in [Ca2+]i in a PLC-dependent manner. The present work tests whether NK2R can signal TRPC. We applied standard whole cell patch-clamp recordings to HEK293 cells stably transfected with the human TRP3 channels (TRP3C), and transiently transfected with a functional NK2R-EGFP. Bath applied Substance P (SP, 1 μM) induced an Icat in the cells expressing both TRP3C and NK2R. Icat reached its peak value in approximately 3 min (195 ± 120.0 s, mean ± SE, n = 20), had a peak density of 11.3 ± 3.48 pA/pF ( n = 24), and was blocked by an NK2R-specific antagonist (SR48968, 100 nM). The Erev value for the SP current was 6.8 ± 7.66 mV ( n = 6), suggestive of a nonspecific cation channel. Icat was not measurable in TRP3C-expressing HEK293 cells without NK2R expression ( n = 6) or in wild-type HEK293 cells with NK2R expression ( n = 12). These data indicate that NK2R can be functionally coupled to TRP channels in HEK293 cells and suggest that SP-induced cation currents in vagal primary sensory neurons might be mediated by TRPC.
Visual-Ocular Motor Activity in the Macaque Pregeniculate Complex
Authors: Livingston Christine A. , Fedder Stacey Rickert
Published: May 2006

The anatomical connections of the pregeniculate complex (PrGC) with components of the visual-ocular motor system suggested its contribution to ocular motor behavior. Subsequent studies reported saccade-related activity in the primate PrGC. To determine its contribution, we characterized pregeniculate units ( n = 128) in alert macaques during ocular motor tasks and visual stimulation. We found that 36/109 saccade-related units exhibited postsaccadic bursts or pauses in tonic discharge for saccades of any amplitude or direction. In contrast to previous results, 46/109 responses preceded or coincided with the saccade, while 47/109 responses were directionally tuned. Pregeniculate units were modulated not only in association with saccades (109/128) but also with smooth eye movements and visual motion (20/128) or eye position (23/128). Multiple ocular motor signals were recorded from 19% of the units, indicating signal convergence on individual neurons. Visual responses were demonstrated in 51% of PrGC units: visual field illumination modulated the resting discharge of 33 units; the responses of 37 saccade-related units and all 23 position-dependent units were modulated by visual stimulation. Early saccadic activity in the PrGC suggests that it contributes more to gaze than postsaccadic modulation of visual or ocular motor activity. The patterns of saccadic responses and the modulation of PrGC activity in association with a variety of visual-ocular motor behaviors suggest its potential role as a relay between the parietal cortex and elements of the brain stem ocular motor pathways, such as the superior colliculus and pretectal nucleus of the optic tract.
Synaptically Evoked GABA Transporter Currents in Neocortical Glia
Authors: Kinney Gregory A. , Spain William J.
Published: May 2006

The presence, magnitude, and time course of GABA transporter currents were investigated in electrophysiologically characterized neocortical astrocytes in an in vitro slice preparation. On stimulation with a bipolar-tungsten stimulating electrode placed nearby, the majority of cells tested displayed long-lasting GABA transporter currents using both single and repetitive stimulation protocols. Using subtype-specific GABA transporter antagonists, long-lasting GABA transporter currents were identified in neocortical astrocytes that originated from at least two subtypes of GABA transporters: GAT-1 and GAT-2/3. These transporter currents displayed slow rise times and long decay times, contrasting the time course observed for glutamate transporter currents, and are indicative of a long extracellular time course of GABA as well as a role for glial GABA transporters during synaptic transmission.
Local Application of Dopamine Inhibits Pyramidal Tract Neuron Activity in the Rodent Motor Cortex
Authors: Awenowicz Patrick W. , Porter Linda L.
Published: May 2006

Cortical neurons respond in a variety of ways to locally applied dopamine, perhaps because of the activation of different receptors within or among subpopulations of cells. This study was conducted to assess the effects of dopamine and the receptor subtypes that mediate the responses of a specific population of neurons, the pyramidal tract neurons (PTNs) in the rodent motor cortex. The specific subfamilies of dopamine receptors expressed by PTNs also were determined. PTNs were identified by antidromic stimulation in intact animals. Extracellular recordings of their spontaneous activity and glutamate-induced excitation were performed with multi-barrel pipettes to allow simultaneous recording and iontophoresis of several drugs. Prolonged (30 s) application of dopamine caused a progressive, nonlinear decrease in spontaneous firing rates for nearly all PTNs, with significant reductions from baseline spontaneous activity (71% of baseline levels) occurring between 20 and 30 s of iontophoresis. The D1 selective (SCH23390) and the D2 selective (eticlopride) antagonists were both effective in blocking dopamine-induced inhibition in nearly all PTNs. Mean firing levels were maintained within 3% of baseline levels during co-application of the D1 antagonist with dopamine and within 11% of baseline levels during co-application of the D2 antagonist and dopamine. SCH23390 was ineffective however, in 2 of 16 PTNs, and eticlopride was ineffective in 3 PTNs. The dopamine blockade by both antagonists in most neurons, along with the selective blockade by one, but not the other antagonist in a few neurons indicate that the overall population of PTNs exhibits a heterogeneous expression of dopamine receptors. The firing rate of PTNs was significantly enhanced by iontophoresis of glutamate (mean = 141% of baseline levels). These increases were attenuated significantly (mean= 98% of baseline) by co-application with dopamine in all PTNs, indicating dopaminergic interactions with glutamate transmission. The expression of dopamine receptors was studied with dual-labeling techniques. PTNs were identified by retrograde labeling with fast blue and the D1a, D2, or D5 receptor proteins were stained immunohistochemically. Some, but not all PTNs, showed labeling for D1a, D2, or D5 receptors. The D1a and D2 receptor immunoreactivity was observed primarily in the somata of PTNs, whereas D5 immunoreactivity extended well into the apical dendrites of PTNs. In accordance with findings of D1 and D2 receptor antagonism of dopamine's actions, the identification of three DA receptor subtypes on PTNs suggests that dopamine can directly modulate PTN activity through one or more receptor subtypes.
Short-Term Desensitization of G-Protein-Activated, Inwardly Rectifying K+(GIRK) Currents in Pyramidal Neurons of Rat Neocortex
Authors: Sickmann Thomas , Alzheimer Christian
Published: May 2006

Whole cell recordings from acutely isolated rat neocortical pyramidal cells were performed to study the kinetics and the mechanisms of short-term desensitization of G-protein-activated, inwardly rectifying K+(GIRK) currents during prolonged application (5 min) of baclofen, adenosine, or serotonin. Most commonly, desensitization of GIRK currents was characterized by a biphasic time course with average time constants for fast and slow desensitization in the range of 8 and 120 s, respectively. The time constants were independent of the agonist used to evoke the current. The biphasic time course was preserved in perforated-patch recordings, indicating that neither component of desensitization is attributable to cell dialysis. Desensitization of GIRK currents displayed a strong heterologous component in that application of a second agonist substantially reduced the responsiveness to a test agonist. Fast desensitization, but not slow desensitization, was lost in cells loaded with GDP, suggesting that the hydrolysis cycle of G proteins might underlie the initial, rapid current decline. Hydrolysis of phosphatidylinositol biphosphate is an unlikely candidate underlying short-term desensitization, because both components of desensitization were preserved in the presence of the phospholipase C inhibitor U73122. We conclude that short-term desensitization does neither result from receptor downregulation nor from altered channel gating but might involve modifications of the G-protein-dependent pathway that serves to translate receptor activation into channel opening.
Encoding of Sound Localization Cues by an Identified Auditory Interneuron: Effects of Stimulus Temporal Pattern
Authors: Samson Annie-Hélène , Pollack Gerald S.
Published: May 2006

An important cue for sound localization is binaural comparison of stimulus intensity. Two features of neuronal responses, response strength, i.e., spike count and/or rate, and response latency, vary with stimulus intensity, and binaural comparison of either or both might underlie localization. Previous studies at the receptor-neuron level showed that these response features are affected by the stimulus temporal pattern. When sounds are repeated rapidly, as occurs in many natural sounds, response strength decreases and latency increases, resulting in altered coding of localization cues. In this study we analyze binaural cues for sound localization at the level of an identified pair of interneurons (the left and right AN2) in the cricket auditory system, with emphasis on the effects of stimulus temporal pattern on binaural response differences. AN2 spike count decreases with rapidly repeated stimulation and latency increases. Both effects depend on stimulus intensity. Because of the difference in intensity at the two ears, binaural differences in spike count and latency change as stimulation continues. The binaural difference in spike count decreases, whereas the difference in latency increases. The proportional changes in response strength and in latency are greater at the interneuron level than at the receptor level, suggesting that factors in addition to decrement of receptor responses are involved. Intracellular recordings reveal that a slowly building, long-lasting hyperpolarization is established in AN2. At the same time, the level of depolarization reached during the excitatory postsynaptic potential (EPSP) resulting from each sound stimulus decreases. Neither these effects on membrane potential nor the changes in spiking response are accounted for by contralateral inhibition. Based on comparison of our results with earlier behavioral experiments, it is unlikely that crickets use the binaural difference in latency of AN2 responses as the main cue for determining sound direction, leaving the difference in response strength, i.e., spike count and/or rate, as the most likely candidate.
Functional Properties of Brain Areas Associated With Motor Execution and Imagery
Authors: Hanakawa Takashi , Immisch Ilka , Toma Keiichiro , Dimyan Michael A. , Van Gelderen Peter , Hallett Mark
Published: May 2006

Imagining motor acts is a cognitive task that engages parts of the executive motor system. While motor imagery has been intensively studied using neuroimaging techniques, most studies lack behavioral observations. Here, we used functional MRI to compare the functional neuroanatomy of motor execution and imagery using a task that objectively assesses imagery performance. With surface electromyographic monitoring within a scanner, 10 healthy subjects performed sequential finger-tapping movements according to visually presented number stimuli in either a movement or an imagery mode of performance. We also examined effects of varied and fixed stimulus types that differ in stimulus dependency of the task. Statistical parametric mapping revealed movement-predominant activity, imagery-predominant activity, and activity common to both movement and imagery modes of performance (movement-and-imagery activity). The movement-predominant activity included the primary sensory and motor areas, parietal operculum, and anterior cerebellum that had little imagery-related activity (−0.1 ∼ 0.1%), and the caudal premotor areas and area 5 that had mild-to-moderate imagery-related activity (0.2 ∼ 0.7%). Many frontoparietal areas and posterior cerebellum demonstrated movement-and-imagery activity. Imagery-predominant areas included the precentral sulcus at the level of middle frontal gyrus and the posterior superior parietal cortex/precuneus. Moreover, activity of the superior precentral sulcus and intraparietal sulcus areas, predominantly on the left, was associated with accuracy of the imagery task performance. Activity of the inferior precentral sulcus (area 6/44) showed stimulus-type effect particularly for the imagery mode. A time-course analysis of activity suggested a functional gradient, which was characterized by a more “executive” or more “imaginative” property in many areas related to movement and/or imagery. The results from the present study provide new insights into the functional neuroanatomy of motor imagery, including the effects of imagery performance and stimulus-dependency on brain activity.
Involvement of the Dorsolateral Prefrontal Cortex of Monkeys in Visuospatial Target Selection
Authors: Iba Michiyo , Sawaguchi Toshiyuki
Published: May 2006

To examine the involvement of the dorsolateral prefrontal cortex (PFC) in visuospatial target selection, we induced local, reversible inactivation with muscimol at various sites in the dorsolateral PFC of two rhesus monkeys while they performed oculomotor visual search (OVS) and oculomotor detection (OD) tasks. The OVS task required the subject to select a target stimulus from among distractors and to make a saccade to the target location (target selection was required for correct performance), whereas the OD task only required a saccade to the target (target selection was not required for correct performance). The local injection of muscimol (5 μg, 1 μl) into the dorsolateral PFC induced a specific deficit in the OVS task but not in the OD task. The deficit in the OVS task was characterized by the disordering of saccades for some (mostly a few) particular target locations as well as by prolongation of the time required for the visual search in most cases. The target locations affected by muscimol were biased to the contralateral visual field. Further, the OVS task with “pop-out” and “non-pop-out” conditions was similarly impaired by muscimol injection. These results suggest that the dorsolateral PFC plays a role in target selection in visual space to guide goal-directed motor acts and particular sites are involved in target selection for a particular visuospatial coordinate. Further, this function of the dorsolateral PFC appears to involve both top-down (active) and bottom-up (passive) target-selection/selective attention processes to control interfering information (distractors).
Problem of Dural Scarring in Recording From Awake, Behaving Monkeys: A Solution Using 5-Fluorouracil
Authors: Spinks R. L. , Baker S. N. , Jackson A. , Khaw P. T. , Lemon R. N.
Published: May 2006

In studies using single neuron recordings from awake, behaving monkeys, it is necessary to make repeated transdural penetrations using fragile microelectrodes. The tough connective tissue that accumulates after the dura mater is first exposed is often problematic because of electrode breakage and the mechanical stress to the underlying brain tissue caused by excessive dimpling during penetration. We describe the use of an antimitotic compound, 5-fluorouracil (5FU) to control the growth of this connective tissue. 5FU can be safely applied for short periods to the exposed dural tissue on a regular basis provided that it is thoroughly rinsed after application. The advantages of using 5FU are fourfold: first, it depresses fibroblast division and minimizes dural growth and scar tissue formation so that penetrations are easier with less electrode damage or breakage. Second, the frequency of surgical procedures required to remove this tissue are greatly reduced, which benefits both the experiment animal and the experiment. Third, 5FU reduces vascularization of the tissue so that its removal is far easier and without significant blood loss. Finally, 5FU seems to inhibit bacterial infections within the recording chamber. In macaque motor cortex, we performed a quantitative study of electrophysiological data recorded from monkeys with and without 5FU treatment. No significant deleterious side effects produced by 5FU could be detected. Likewise, histological examination of cortical tissue underlying treated dura did not reveal any obvious signs of damage by 5FU. We recommend this approach, with the appropriate safety precautions, to all those neurophysiologists using transdural microelectrode methods in chronically prepared experimental animals. It is also possible that this technique may be useful in other situations where there is dural scarring after surgical intervention or injury.
Recruitment Order of Motor Units in Human Vastus Lateralis Muscle Is Maintained During Fatiguing Contractions
Authors: Adam Alexander , De Luca Carlo J.
Published: May 2006

Motor-unit firing patterns were studied in the vastus lateralis muscle of five healthy young men [21.4 ± 0.9 (SD) yr] during a series of isometric knee extensions performed to exhaustion. Each contraction was held at a constant torque level, set to 20% of the maximal voluntary contraction at the beginning of the experiment. Electromyographic signals, recorded via a quadrifilar fine wire electrode, were processed with the precision decomposition technique to identify the firing times of individual motor units. In repeat experiments, whole-muscle mechanical properties were measured during the fatigue protocol using electrical stimulation. The main findings were a monotonic decrease in the recruitment threshold of all motor units and the progressive recruitment of new units, all without a change of the recruitment order. Motor units from the same subject showed a similar time course of threshold decline, but this decline varied among subjects (mean threshold decrease ranged from 23 to 73%). The mean threshold decline was linearly correlated ( R2 ≥ 0.96) with a decline in the elicited peak tetanic torque. In summary, the maintenance of recruitment order during fatigue strongly supports the notion that the observed common recruitment adaptations were a direct consequence of an increased excitatory drive to the motor unit pool. It is suggested that the increased central drive was necessary to compensate for the loss in force output from motor units whose muscle fibers were actively contracting. We therefore conclude that the control scheme of motor-unit recruitment remains invariant during fatigue at least in relatively large muscles performing submaximal isometric contractions.