bluuebunny/crossref_metadata_2025 huggingface dataset:
Diversity and rarity hotspots and conservation of butterfly communities in and around the Aokigahara woodland of Mount Fuji, central Japan
Authors: Kitahara Masahiko , Watanabe Maki
Published: December 2004

In central Japan, Aokigahara woodland is considered to be one of the most natural areas around Mount Fuji and a core area in the conservation of the biodiversity of Mount Fuji. We chose butterflies as an indicator species of biodiversity and examined six communities in and around the woodland in 2000 using transect counts to examine and search for diversity and rarity hotspots and their associated landscapes. The results showed that butterfly species richness and species diversities H′ 1/λ were significantly higher in forest‐edge sites than in forest‐interior and/or open‐land sites, and variation in the total number of species among these three landscape types was well accounted for by ecologically specialist species, such as landscape specifics, oligovoltines, narrow diet feeders and low‐density species. Thus, the species regarded as vulnerable to extinction, including Red List species, were observed more often in forest‐edge sites than in forest‐interior and/or open‐land sites. As a result, in the study area, diversity and rarity hotspots were found in forest‐edge landscapes. The reasons why butterfly diversity and rarity hotspots were established in forest‐edge landscapes were analyzed and interpreted from several points of view, including disturbance level, landscape elements and plant species richness. From these results, and the fact that some species were confined to forest‐interior sites, we conclude that it is very important to conserve and manage forest‐edge habitats (considered to be semi‐natural) as well as forest‐interior habitats (considered to be the most natural) to maintain the diversity of butterfly communities and preserve the various types of threatened species in and around the Aokigahara woodland.
Ketamine: Its use in the emergency department
Authors: Cromhout Andries
Published: December 2004

Ketamine has been known to the medical world for over 30 years, yet is not widely used to its full potential. It is often considered to be a ‘third world’ drug only. In light of a recent increase in interest in its use in the developed world, this review is for emergency physicians to use as a quick reference.
Red‐back spider envenomation in children in Central Australia
Authors: Trethewy Christopher E , Bolisetty Srinivas , Wheaton Gavin
Published: December 2004

Objective:   To describe the clinical spectrum of Red‐back spider (RBS) envenomation in children up to 12 years of age.

Methods:   Retrospective case notes review of children with a discharge diagnosis of RBS bite from January 1992 to June 2001. The setting was Alice Springs Hospital, the main paediatric hospital for the whole region of Central Australia. The patients were 54 children, comprising 39 Aboriginal and 15 non‐Aboriginal children.

Results:  Forty‐six (85%) children had systemic envenomation. The three most common systemic features are irritability, hypertension and sweating; 35 (65%) children had all three systemic features. Forty‐five (83%) received antivenom therapy. The clinical characteristics and outcomes showed no significant difference between children  4 and > 4 years of age.

Conclusions:  There is a high incidence of systemic envenomation due to RBS bite in children in Central Australia. The triad of irritability, hypertension and sweating in a previously well child is highly suggestive of latrodectism.
Stage‐specific activity patterns affect motoneuron axonal retraction and outgrowth during the metamorphosis of Manduca sexta
Authors: Duch C. , Mentel T.
Published: December 2004

During the metamorphosis of holometabolous insects, most larval muscles and sensory neurons are replaced by new adult elements, whereas most motoneurons persist and are remodelled to serve new adult functions. In Manduca sexta, the formation of the anlagen of the adult dorsal longitudinal flight muscle (DLM) is characterized by retraction of axonal terminals and dendrites of persisting larval motoneurons, partial target muscle degeneration and myoblast accumulation during late larval life. Most of these structural changes have been attributed to hormonal control, not only because ecdysteroids govern metamorphosis, but also because motoneurons express ecdysteroid receptors and experimental manipulations of ecdysteroid titres perturb normal development. To test whether activity‐dependent mechanisms also came into play, chronic extracellular recordings were conducted in vivo from the five future DLM motoneurons throughout the last 3 days of larval life. Motoneuron activity is regulated developmentally. The types of motoneurons recruited, the number of motor spikes and the duration of bursts change in a stereotypical fashion during different stages, indicating an internal control of motor activity. A characteristic cessation in the activity of the five future DLM motoneurons coincides in time with the retraction of their dendrites and their terminal arborizations, whereas their activation during ecdysis coincides with the onset of new outgrowth. Inducing advanced activity by stimulating the motoneurons selectively with ecdysis‐like patterns results in significant outgrowth of their terminal arborizations. Therefore, steroids might act in concert with activity‐dependent mechanisms during the postembryonic modifications of neuromuscular systems.
Direct and indirect interactions between cannabinoid CB1 receptor and group II metabotropic glutamate receptor signalling in layer V pyramidal neurons from the rat prefrontal cortex
Authors: Barbara Jean‐Gaël , Auclair Nathalie , Roisin Marie‐Paule , Otani Satoru , Valjent Emmanuel , Caboche Jocelyne , Soubrie Philippe , Crepel Francis
Published: December 2004

At proximal synapses from layer V pyramidal neurons from the rat prefrontal cortex, activation of group II metabotropic glutamate receptors (group II mGlu) by (2S,2′R,3′R)‐2‐(2′,3′‐dicarboxycyclopropyl) glycine (DCG IV) induced a long‐lasting depression of excitatory postsynaptic currents. Paired‐pulse experiments suggested that the depression was expressed presynaptically. Activation of type 1 cannabinoid receptors (CB1) by WIN 55,212‐2 occluded the DCG IV‐induced depression in a mutually occlusive manner. At the postsynaptic level, WIN 55,212‐2 and DCG IV were also occlusive for the activation of extracellular signal‐regulated kinase. The postsynaptic localization of active extracellular signal‐regulated kinase was confirmed by immunocytochemistry after activation of CB1 receptors. However, phosphorylation of extracellular signal‐regulated kinase in layer V pyramidal neurons was dependent on the activation of N‐methyl‐d‐aspartate receptors, consequently to a release of glutamate in the local network. Group II mGlu were also shown to be involved in long‐term changes in synaptic plasticity induced by high frequency stimulations. The group II mGlu antagonist (RS)‐alpha‐methylserine‐O‐phosphate monophenyl ester (MSOPPE) favoured long‐term depression. However, no interaction was found between MSOPPE, WIN 55,212‐2 and the CB1 receptor antagonist SR 141716A on the modulation of long‐term depression or long‐term potentiation and the effects of these drugs were rather additive. We suggest that CB1 receptor and group II mGlu signalling may interact through a presynaptic mechanism in the induction of a DCG IV‐induced depression. Postsynaptically, an indirect interaction occurs for activation of extracellular signal‐regulated kinase. However, none of these interactions seem to play a role in synaptic plasticities induced with high frequency stimulations.
Basolateral amygdala modulation of the nucleus accumbens dopamine response to stress: role of the medial prefrontal cortex
Authors: Stevenson C. W. , Gratton A.
Published: December 2004

The basolateral amygdala (BLA) is involved in modulating affective responses to stress and, along with the nucleus accumbens (NAc) and medial prefrontal cortex (mPFC), receives a stress‐responsive dopamine (DA) projection from the ventral tegmental area. The present study was undertaken to characterize the role of BLA DA D1 and D2/D3 receptor subtypes in modulating the NAc and mPFC DA responses to stress. Voltammetry was used to monitor, in freely behaving rats, stress‐induced DA release in NAc or mPFC after injection of D1 (SCH 23390) or D2/D3 (raclopride) receptor antagonist into BLA. Intra‐BLA SCH 23390 injection potentiated stress‐induced NAc DA release but attenuated the mPFC DA stress response; raclopride had no effect on either the NAc or mPFC DA responses to stress. Based on these results, we also examined the possibility that BLA can indirectly modulate the NAc DA stress response via its projection to mPFC. To do so we studied the effects of intra‐mPFC co‐administration of D1 (SKF 38393) and D2/D3 (quinpirole) receptor agonists on the potentiated NAc DA stress response resulting from intra‐BLA SCH 23390 injection. Alone, mPFC D1 and D2/D3 receptor co‐activation had no effect on stress‐induced NAc DA release, but did prevent the potentiated NAc DA stress response produced by BLA D1 receptor blockade. These findings indicate that BLA DA modulates the NAc and mPFC DA stress responses via activation of the D1 receptor subtype. They also suggest that BLA DA modulates stress‐induced NAc DA release indirectly by modulating the mPFC DA response to stress.
Neuronal lineage‐specific induction of phospholipase Cε expression in the developing mouse brain
Authors: Wu Dongmei , Tadano Makoto , Edamatsu Hironori , Masago‐Toda Misa , Yamawaki‐Kataoka Yuriko , Terashima Toshio , Mizoguchi Akira , Minami Yasuhiro , Satoh Takaya , Kataoka Tohru
Published: December 2004

Phospholipase C is a key enzyme of intracellular signal transduction in the central nervous system. We and others recently discovered a novel class of phospholipase C, phospholipase Cε, which is regulated by Ras and Rap small GTPases. As a first step toward analysis of its function, we have examined the spatial and temporal expression patterns of phospholipase Cε during mouse development byin situhybridization and immunohistochemistry. Around embryonic day 10.5, abundant expression of phospholipase Cε is observed specifically in the outermost layer of the neural tube. On embryonic day 12 and later, it is observed mainly in the marginal zone of developing brain and spinal cord as well as in other regions undergoing neuronal differentiation, such as the retina and olfactory epithelium. The phospholipase Cε‐expressing cells almost invariably express microtubule‐associated protein 2, but hardly express nestin or glial fibrillary acidic protein, indicating that the expression of phospholipase Cε is induced specifically in cells committed to the neuronal lineage. The expression of phospholipase Cε persists in the terminally differentiated neurons and exhibits no regional specificity. Further, anin vitroculture system of neuroepithelial stem cells is employed to show that abundant expression of phospholipase Cε occurs in parallel with the loss of nestin expression as well as with the induction of microtubule‐associated protein 2 expression and neuronal morphology. Also, glial fibrillary acidic protein‐positive glial lineage cells do not exhibit the high phospholipase Cε expression. These results suggest that the induction of phospholipase Cε expression may be a specific event associated with the commitment of the neural precursor cells to the neuronal lineage.
Separate processing mechanisms for encoding of geometric and landmark information in the avian hippocampus
Authors: Tommasi Luca , Gagliardo Anna , Andrew Richard J. , Vallortigara Giorgio
Published: December 2004

Domestic chicks bilaterally or unilaterally lesioned to the hippocampus were trained to search for food hidden beneath sawdust by ground‐scratching in the centre of a large enclosure, the correct position of food being indicated by a local landmark in the absence of any extra‐enclosure visual cues. At test, the landmark was removed or displaced at a distance from its original position. Results showed that sham‐operated chicks and chicks with a lesion of the left hippocampus searched in the centre, relying on large‐scale geometric information provided by the enclosure, whereas chicks with a lesion of either the right hippocampus or both hippocampi were completely disoriented (landmark removed) or searched close to the landmark shifted from the centre (landmark displaced). These results indicate that encoding of geometric features of an enclosure occurs in the right hippocampus even when local information provided by a landmark would suffice to localize the goal; encoding based on local information, in contrast, seems to occur outside the hippocampus. These findings provide evidence that the left and right avian hippocampi play different roles in spatial cognition, a phenomenon which had been documented previously only for the human hippocampus.
A hot spot for hotfoot mutations in the gene encoding the δ2 glutamate receptor
Authors: Wang Ying , Matsuda Shinji , Drews Valerie , Torashima Takashi , Meisler Miriam H. , Yuzaki Michisuke
Published: December 2004

The orphan glutamate receptor δ2 is selectively expressed in Purkinje cells and plays a crucial role in cerebellar functions. Recently, ataxia in the hotfoot mouse ho4J was demonstrated to be caused by a deletion in the δ2 receptor gene (Grid2) removing the N‐terminal 170 amino acids of the δ2 receptor. To understand how δ2 receptors function, we characterized mutations in eight additional spontaneously occurring hotfoot alleles of Grid2. The mouse Grid2 gene consists of 16 exons, spanning approximately 1.4 Mb. Genomic DNA analysis showed that seven hotfoot mutants had a deletion of one or more exons encoding the N‐terminal domain of δ2 receptors. The exception is ho5J, which has a point mutation in exon 12. Deletions in ho7J, ho9J, ho11J and ho12J mice result in the in‐frame deletion of between 40 and 95 amino acids. Expression of constructs containing these deletions in HEK293 cells resulted in protein retention in the endoplasmic reticulum or cis‐Golgi without transport to the cell surface. Coimmunoprecipitation assays indicated that these deletions also reduce the intermolecular interaction between individual δ2 receptors. These results indicate that the deleted N‐terminal regions are crucial for oligomerization of δ2 receptors and their subsequent transport to the cell surface of Purkinje cells. The relatively large size of the Grid2 gene may be one of the reasons why many spontaneous mutations occur in this gene. In addition, the frequent occurrence of in‐frame deletions within the N‐terminal domain in hotfoot mutants suggests the importance of this domain in the function of δ2 receptors.
Aversive conditioning following repeated withdrawal from ethanol and epileptic kindling
Authors: Ripley Tamzin L. , Brown Geraldine , Dunworth Sarah J. , Stephens David N.
Published: December 2004

Repeated withdrawal from ethanol, a procedure which resembles amygdala kindling in increasing seizure sensitivity, impairs the acquisition of fear conditioning (Stephens et al., 2001, Eur. J. Neurosci.,14, 2023–31). In contrast, rats previously kindled by repeated electrical stimulation of basolateral amygdala, or repeated administration of pentylenetetrazol, showed increased suppression of operant responding during the presentation of a stimulus conditioned to footshock when conditioning took place several weeks following the kindling experience. Neither form of kindling nor repeated ethanol withdrawal altered taste aversion conditioning, though rats treated chronically with ethanol and given a single withdrawal experience showed enhanced taste aversion conditioning. These results suggest that, despite evidence suggesting a common neuronal mechanism underlying seizure sensitivity following these types of kindling, they differ in their effects on fear conditioning.
Bidirectional synaptic plasticity as a consequence of interdependent Ca2+‐controlled phosphorylation and dephosphorylation pathways
Authors: D'Alcantara Pablo , Schiffmann Serge N. , Swillens Stéphane
Published: December 2004

Postsynaptic Ca2+ signals of different amplitudes and durations are able to induce either long‐lasting potentiation (LPT) or depression (LTD). The bidirectional character of synaptic plasticity may result at least in part from an increased or decreased responsiveness of the glutamatergic α‐amino‐3‐hydroxy‐5‐methylisoxazole‐4‐propionic acid receptor (AMPA‐R) due to the modification of conductance and/or channel number, and controlled by the balance between the activities of phosphorylation and dephosphorylation pathways. AMPA‐R depression can be induced by a long‐lived Ca2+ signal of moderate amplitude favouring the activation of the dephosphorylation pathway, whereas a shorter but higher Ca2+ signal would induce AMPA‐R potentiation resulting from the preferential activation of the phosphorylation pathway. Within the framework of a model involving calcium/calmodulin‐dependent protein kinase II (CaMKII), calcineurin (PP2B) and type 1 protein phosphatase (PP1), we aimed at delineating the conditions allowing a biphasic U‐shaped relationship between AMPA‐R and Ca2+ signal amplitude, and thus bidirectional plasticity. Our theoretical analysis shows that such a property may be observed if the phosphorylation pathway: (i) displays higher cooperativity in its Ca2+‐dependence than the dephosphorylation pathway; (ii) displays a basal Ca2+‐independent activity; or (iii) is directly inhibited by the dephosphorylation pathway. Because the experimentally observed inactivation of CaMKII by PP1 accounts for this latter characteristic, we aimed at verifying whether a realistic model using reported parameters values can simulate the induction of either LTP or LTD, depending on the time and amplitude characteristics of the Ca2+ signal. Our simulations demonstrate that the experimentally observed bidirectional nature of Ca2+‐dependent synaptic plasticity could be the consequence of the PP1‐mediated inactivation of CaMKII.
Objects automatically potentiate action: an fMRI study of implicit processing
Authors: Grèzes J. , Tucker M. , Armony J. , Ellis R. , Passingham R. E.
Published: December 2004

Behavioural data have shown that the perception of an object automatically potentiates motor components (affordances) of possible actions toward that object, irrespective of the subject's intention. We carried out an event‐related fMRI study to investigate the influence of the intrinsic properties of an object on motor responses which were either compatible or incompatible with the action that the object affords. The subjects performed power or precision grip responses based on the categorization of objects into natural or man‐made. The objects were either ‘small’ (usually grasped with a precision grip) or ‘large’ (usually grasped with a power grip). As expected, the motor responses were fastest to objects that afforded the same grip (congruent) and slowest to objects that afforded the other grip (incongruent). Imaging revealed activations which covaried with compatibility in the parietal, dorsal premotor and inferior frontal cortex. We suggest that the greater the difference in reaction times between congruent and incongruent trials, the greater the competition between the action afforded by the object and the action specified by the task, and thus the greater the activation within this network.
Formation of dendritic spines in cultured striatal neurons depends on excitatory afferent activity
Authors: Segal Menahem , Greenberger Varda , Korkotian Eduard
Published: December 2004

The role of afferent innervation in the formation of dendritic spines was studied in cultured rat striatum. The striatum is a unique structure in that it contains highly spiny GABAergic projection neurons, with no known local excitation. Grown alone in culture, striatal neurons did not express spontaneous network activity and were virtually devoid of dendritic spines. Adding GFP‐expressing mouse cortical neurons to the striatal culture caused the appearance of spontaneous and evoked excitatory synaptic currents in the striatal neurons and a 10‐fold increase in the density of spines on their dendrites. This effect was blocked by a continuous presence of TTX in the growth medium, while removal of the drug caused a rapid appearance of spines. Exposure to glutamate, or the presence of cortex‐conditioned medium did not mimic the effect of cortical neurons on formation of spines in the striatal neurons. Also, the cortical innervation did not cause a selective enhancement of survival of specific subtypes of spiny striatal neurons. These experiments demonstrate that excitatory afferents are necessary for the formation of dendritic spines in striatal neurons.
Increased vulnerability to kainic acid‐induced epileptic seizures in mice underexpressing the scaffold protein Islet‐Brain 1/JIP‐1
Authors: Magara Fulvio , Haefliger Jacques‐Antoine , Thompson Nancy , Riederer Beat , Welker Egbert , Nicod Pascal , Waeber Gérard
Published: December 2004

Islet‐Brain 1, also known as JNK‐interacting protein‐1 (IB1/JIP‐1) is a scaffold protein mainly involved in the regulation of the pro‐apoptotic signalling cascade mediated by c‐Jun–N‐terminal kinase (JNK). IB1/JIP‐1 organizes JNK and upstream kinases in a complex that facilitates JNK activation. However, overexpression of IB1/JIP‐1 in neurons in vitro has been reported to result in inhibition of JNK activation and protection against cellular stress and apoptosis. The occurrence and the functional significance of stress‐induced modulations of IB1/JIP‐1 levels in vivo are not known. We investigated the regulation of IB1/JIP‐1 in mouse hippocampus after systemic administration of kainic acid (KA), in wild‐type mice as well as in mice hemizygous for the gene MAPK8IP1, encoding for IB1/JIP‐1. We show here that IB1/JIP‐1 is upregulated transiently in the hippocampus of normal mice, reaching a peak 8 h after seizure induction. Heterozygous mutant mice underexpressing IB1/JIP‐1 showed a higher vulnerability to the epileptogenic properties of KA, whereas hippocampal IB1/JIP‐1 levels remained unchanged after seizure induction. Subsequently, an increasing activation of JNK in the 8 h following seizure induction was observed in IB1/JIP‐1 haploinsufficient mice, which also underwent more severe excitotoxic lesions in hippocampal CA3, as assessed histologically 3 days after KA administration. Taken together, these data indicate that IB1/JIP‐1 in hippocampus participates in the regulation of the neuronal response to excitotoxic stress in a level‐dependent fashion.
Calcium‐activated cationic channel in rat sensory neurons
Authors: Cho Hawon , Kim Man Su , Shim Won Sik , Yang Young Duk , Koo Jaeyeon , Oh Uhtaek
Published: December 2004

Ion channels in sensory neurons are molecular sensors that detect external stimuli and transduce them to neuronal signals. Although Ca2+‐activated nonselective cation (CAN) channels were found in many cell types, CAN channels in mammalian sensory neurons are not yet identified. In the present study, we describe an ion channel that is activated by intracellular Ca2+ in cultured rat sensory neurons. Half‐maximal concentration of Ca2+ in activating the CAN channel was approximately 780 µm. The current–voltage relationship of this channel was linear with a unit conductance of 28.8 ± 0.4 pS at −60 mV in symmetrical 140 mm Na+ solution. The CAN channel was permeable to monovalent cations such as Na+, K+, Cs+, and Li+, but poorly permeable to Ca2+. The CAN channel in mammalian sensory neurons was reversibly blocked by intracellular adenine nucleotides, such as ATP, ADP, and AMP. Interestingly, single‐channel currents activated by Ca2+ were blocked by fenamates, such as flufenamic acid, a class of nonsteroidal anti‐inflammatory drugs. Thus, these results suggest that CAN channels in mammalian sensory neurons would participate in modulating nociceptive neural transmission in response to ever‐changing intracellular Ca2+ in the local microenvironment.
Greater orbitofrontal activity predicts better memory for faces
Authors: Frey Stephen , Petrides Michael
Published: December 2004

Having demonstrated recently that the orbitofrontal cortex is selectively involved when novel abstract visual information is encoded, we investigated whether the same orbitofrontal area would be activated during the encoding of novel human faces. The present positron emission tomography study demonstrated that area 11 in the right orbitofrontal region, which is directly linked to the medial temporal lobe, is a critical frontal area selectively activated when normal human subjects are engaged in encoding visually presented faces. Furthermore, better face recognition performance correlated with greater cerebral blood flow specifically in this orbitofrontal area.
Degeneration of sensory outer hair cells following pharmacological blockade of cochlear KCNQ channels in the adult guinea pig
Authors: Nouvian Régis , Ruel Jérôme , Wang Jing , Guitton Matthieu J. , Pujol Rémy , Puel Jean‐Luc
Published: December 2004

In the inner ear, hair cell function is inextricably linked with intracellular potassium homeostasis. KCNQ potassium channels may play an important role by preventing accumulation of potassium in the hair cells. Linopirdine, a tool useful in targeting native or heterologous KCNQ channels, was used to study the role of KCNQ channels in the guinea pig cochlea. When perfused into intact cochlea, linopirdine transiently increases the summating potential and endocochlear potential, suggesting that it alters K+ homeostasis. The concomitant decrease in cochlear microphonic potential and distortion product otoacoustic emission amplitude indicates that linopirdine has an effect on the outer hair cells (OHCs). To determine the pathological consequences of the inhibition of cochlear KCNQ channels, we developed a hearing loss model based on a chronic intracochlear perfusion of linopirdine via an osmotic minipump. Ultrastructural analysis reveals that KCNQ channel blockade leads to OHC degeneration. Together, these results demonstrate that KCNQ channels, most probably of the KCNQ4 subtype, are crucial for the function and survival of sensory OHCs. Clinically, KCNQ4 channel dysfunction is known to be associated with the DFNA2 form of nonsyndromic dominant deafness. Our study shows that OHC KCNQ4 dysfunction could contribute to the early (40dB) hearing loss, but not for the profound deafness observed at the final stage of this disease.
Dopamine receptor supersensitivity in rat subthalamus after 6‐hydroxydopamine lesions
Authors: Shen Ke‐Zhong , Zhu Zi‐Tao , Munhall Adam , Johnson Steven W.
Published: December 2004

The subthalamic nucleus (STN) receives direct dopaminergic innervation from the substantia nigra pars compacta, but the importance of this input in the pathophysiology of parkinsonism remains to be determined. We used whole‐cell patch‐clamp recordings in brain slices to study presynaptic dopaminergic modulation of synaptic inputs to the STN in unilateral 6‐hydroxydopamine (6‐OHDA)‐lesioned rats. Here, we report that dopamine was more potent for inhibiting GABA IPSCs and glutamate EPSCs in the STN ipsilateral to the lesion, and was less potent for suppressing IPSCs and EPSCs in the STN contralateral to the lesion, compared with the effects of dopamine in control STN. Dopamine reduced IPSCs with an IC50 value of 20.9 ± 3.6 µm in control STN, whereas IC50 values were 0.83 ± 0.15 and 55.1 ± 11.1 µm in STN ipsilateral and contralateral to 6‐OHDA lesions, respectively. Dopamine also inhibited EPSCs with an IC50 value of 12.8 ± 2.8 µm in control STN, whereas IC50 values were 4.5 ± 0.9 and 41.6 ± 9.8 µm in STN ipsilateral and contralateral to 6‐OHDA lesions, respectively. Results with paired stimuli to evoke EPSCs and IPSCs suggest that endogenous dopamine acts presynaptically to inhibit transmitter release in the STN. These results show that chronic dopamine denervation significantly alters the regulation of synaptic input to the STN. Our results also suggest that the STN may be an important target for levodopa therapy in Parkinson's disease.
Density‐dependent mortality in Pacific salmon: the ghost of impacts past?
Authors: Achord Stephen , Levin Phillip S. , Zabel Richard W.
Published: December 2004

Conservation biologists often ignore density dependence because at‐risk populations are typically small relative to historical levels. However, if populations are reduced as a result of impacts that lower carrying capacity, then density‐dependent mortality may exist at low population abundances. Here, we explore this issue in threatened populations of juvenile chinook salmon (Oncorhynchus tshawytscha). We followed the fate of more than 50 000 juvenile chinook in the Snake River Basin, USA to test the hypothesis that their survival was inversely associated with juvenile density. We also tested the hypotheses that non‐indigenous brook trout and habitat quality affect the presence or strength of density dependence. Our results indicate that juvenile chinook suffer density‐dependent mortality and the strength of density dependence was greater in streams in which brook trout were absent. We were unable to detect an effect of habitat quality on the strength of density dependence. Historical impacts of humans have greatly reduced population sizes of salmon, and the density dependence we report may stem from a shortage of nutrients normally derived from decomposing salmon carcasses. Cohorts of juvenile salmon may experience density‐dependent mortality at population sizes far below historical levels and recovery of imperiled populations may be much slower than currently expected.
ENSO, rainfall and temperature influences on extreme population declines among African savanna ungulates
Authors: Ogutu Joseph O. , Owen‐Smith Norman
Published: December 2004

Climatic variation associated with the North Atlantic Oscillation (NAO) and El Niño‐Southern Oscillation (ENSO) has a widespread influence on the population dynamics of many organisms worldwide. While previous analyses have related the dynamics of northern ungulates to the NAO, there has been no comparable assessment for the species rich assemblages of tropical and subtropical Africa. Census records for 11 ungulate species in South Africa's Kruger National Park over 1977–96 reveal severe population declines by seven species, which were inadequately explained by indices of ENSO or its effects on annual rainfall totals. An additional influence was an extreme reduction in dry season rainfall, concurrent with and perhaps related to a regional temperature rise, possibly a signal of global warming. Boundary fencing now restricts range shifts by such large mammals in response to climatic variation. Our models project near extirpation of three ungulate species from the park's fauna should these climatic conditions recur.
Behaviourally structured populations persist longer under harsh environmental conditions
Authors: Petrovskii Sergei V. , Blackshaw Rod P.
Published: December 2004

The factors and mechanisms that enhance population persistence in a fragmented habitat and/or under harsh environmental conditions are of significant current interest. We consider the dynamics of a population in an isolated habitat surrounded by an unfavourable environment subject to different behavioural responses between the individuals. We assume that there are two responses available: one of them is aggression in its extreme form, the other is its contrary when an individual takes flight in order to avoid any contact with its conspecific. We show that a behaviourally structured population consisting of individuals with fixed behavioural responses is intrinsically less prone to extinction under harsh environmental condition than a population where the individuals can ‘choose’ between the two given behaviours. We also show that, contrary to an intuitively expected negative impact of aggression on population persistence, the optimal conditions for population persistence are reached when a considerable proportion of the individuals exhibit aggressive behaviour.
Stable isotope probing of rRNA and DNA reveals a dynamic methylotroph community and trophic interactions with fungi and protozoa in oxic rice field soil
Authors: Lueders Tillmann , Wagner Bianca , Claus Peter , Friedrich Michael W.
Published: December 2004

Stable isotope probing (SIP) is a novel technique to characterize structure and in situ function of active microbial populations, which is based on the incorporation of 13C‐labelled substrates into nucleic acids. Here, we have traced methylotrophic members of a rice field soil microbial community, which became active upon continuous addition of 13C‐methanol (<22 mM) as studied in microcosms. By combining rRNA‐ and DNA‐based SIP, as well as domain‐specific real‐time PCR detection of templates in fractions of centrifugation gradients, we were able to detect 13C‐labelled bacterial rRNA after 6 days of incubation. Fingerprinting and comparative sequence analysis of ‘heavy’ bacterial rRNA showed that mostly members of the Methylobacteriaceae and a novel clade within the Methylophilaceae formed part of the indigenous methylotrophic community. Over time, however, the Methylophilaceae were enriched. Unexpectedly, nucleic acids of eukaryotic origin were detected, mostly in intermediately 13C‐labelled gradient fractions. These eukaryotes were identified as fungi mostly related to Fusarium and Aspergillus spp., and also Cercozoa, known as predatory soil flagellates. The detection of fungi and protozoa in 13C‐enriched nucleic acid fractions suggests a possible involvement in either direct assimilation of label by the fungi, or a food web, i.e. that primary 13C‐methanol consuming methylotrophs were decomposed by fungi and grazed by protozoa.
Competitive interactions between Microdochium nivale var. majus, M. nivale var. nivale and Fusarium culmorum in planta and in vitro
Authors: Simpson Duncan R. , Thomsett Martha A. , Nicholson Paul
Published: December 2004

Microdochium nivale var. majus and var. nivale are economically important fungal pathogens of cereal seedlings, stem bases and ears, as is the toxigenic species Fusarium culmorum. Competition experiments on seedlings support an earlier report of differential host preference between the varieties of M. nivale on wheat and rye seedlings at 15°C, but showed that it does not extend across a broad range of temperatures. The studies showed that, although interaction is disadvantageous to the less virulent pathogen, it does not confer an advantage to the more virulent pathogen. In mixed inoculum experiments on wheat seedlings at 15°C and 20°C, F. culmorum suppressed the growth of both varieties of M. nivale. However, if M. nivale var. majus became established on the seedlings, it was able to co‐suppress colonization of wheat seedlings by F. culmorum. In contrast M. nivale var. nivale did not suppress F. culmorum significantly. The growth of M. nivale var. majus and F. culmorum was also co‐suppressed in liquid culture. Significantly, the accumulation of deoxynivalenol mycotoxin was also reduced in the mixed in vitro culture compared with axenic culture of F. culmorum. However, in vitro interaction studies on solidified media were of only limited use in predicting the outcome of competitions in planta.
Analysis of methanotrophic bacteria in Movile Cave by stable isotope probing
Authors: Hutchens Elena , Radajewski Stefan , Dumont Marc G. , McDonald Ian R. , Murrell J. Colin
Published: December 2004

Movile Cave is an unusual groundwater ecosystem that is supported by in situ chemoautotrophic production. The cave atmosphere contains 1–2% methane (CH4), although much higher concentrations are found in gas bubbles that keep microbial mats afloat on the water surface. As previous analyses of stable carbon isotope ratios have suggested that methane oxidation occurs in this environment, we hypothesized that aerobic methane‐oxidizing bacteria (methanotrophs) are active in Movile Cave. To identify the active methanotrophs in the water and mat material from Movile Cave, a microcosm was incubated with a 10%13CH4 headspace in a DNA‐based stable isotope probing (DNA‐SIP) experiment. Using improved centrifugation conditions, a 13C‐labelled DNA fraction was collected and used as a template for polymerase chain reaction amplification. Analysis of genes encoding the small‐subunit rRNA and key enzymes in the methane oxidation pathway of methanotrophs identified that strains of Methylomonas, Methylococcus and Methylocystis/Methylosinus had assimilated the 13CH4, and that these methanotrophs contain genes encoding both known types of methane monooxygenase (MMO). Sequences of non‐methanotrophic bacteria and an alga provided evidence for turnover of CH4 due to possible cross‐feeding on 13C‐labelled metabolites or biomass. Our results suggest that aerobic methanotrophs actively convert CH4 into complex organic compounds in Movile Cave and thus help to sustain a diverse community of microorganisms in this closed ecosystem.
Induction of prolonged tenderness in patients with tension‐type headache by means of a new experimental model of myofascial pain
Authors: Mørk H. , Ashina M. , Bendtsen L. , Olesen J. , Jensen R.
Published: December 2004

Tenderness is the most prominent abnormal finding in patients with tension‐type headache (TTH). Recently we developed a model of myofascial tenderness using intramuscular infusion of a combination of bradykinin, serotonin, histamine and prostaglandin E2. We aimed to examine tenderness after this combination in patients with episodic TTH (ETTH). Fifteen patients and 15 healthy controls completed the study. Participants received the combination into the non‐dominant trapezius muscle in a randomized, double‐blinded and placebo‐controlled design. Local tenderness and stimulus–response functions, mechanical pain thresholds (PPDT) in the temporal region and on the finger, and total tenderness score (TTS) were recorded. A local, prolonged, and mild to moderate tenderness was reported both in patients (P = 0.001) and in controls (P = 0.001) after the combination compared with the placebo. The response to the combination tended to be increased in patients. The stimulus–response function was leftward shifted after the combination, compared with baseline in both groups. No changes in PPDT or TTS were found after the infusions, whereas baseline PPDTs were decreased in ETTH compared with controls (PPDTfinger: P = 0.033; PPDTtemporal: P = 0.015). Intramuscular infusion of a combination of endogenous substances induced prolonged tenderness in both patients with episodic TTH and healthy subjects. The present results suggest an increased excitability of peripheral muscle afferents in TTH.
Nociceptive‐specific blink reflex and glyceryl trinitrate infusion in healthy volunteers
Authors: Kowacs F. , Giffin N. J. , Putzki N. , Goadsby P. J. , Kaube H.
Published: December 2004

Glyceryl trinitrate (GTN) is known to induce early headache in healthy humans after intravenous infusion. Moreover, in animal models subcutaneous administration produces an increase in Fos expression in brainstem areas that are involved in trigeminal pain processing. In a double‐blind crossover study, we tested the blink reflex before, during and immediately after GTN and placebo intravenous infusion in eight healthy volunteers using a new stimulation electrode that preferentially activates A‐δ nociceptive afferent fibres. The initial hypothesis that GTN could induce an increase in the magnitude of the nociceptive blink reflex R2 component by stimulating activity of trigeminal nucleus caudalis wide dynamic range interneurones was not confirmed. Although mild headache was induced in six subjects, there was no significant change between the R2 area under the curve before and after drug vs. placebo.
Behavioral Disorders in Pediatric Epilepsy: Unmet Psychiatric Need
Authors: Ott Derek , Siddarth Prabha , Gurbani Suresh , Koh Susan , Tournay Anne , Shields W. Donald , Caplan Rochelle
Published: December 2004

Summary:  Purpose: This study examined the relation between psychiatric diagnosis and mental health services in children with epilepsy and the associated demographic, cognitive, linguistic, behavioral, and seizure‐related variables.

Methods: The Kiddie Schedule for Affective Disorders and Schizophrenia (K‐SADS), the Child Behavior Checklist, the Test of Language Development, and the Wechsler Intelligence Scale for Children–Revised (WISC‐R) were administered to 114 children, aged 5 to 16 years, with either complex partial seizures (CPS) or primary generalized with absence (PGE, petit mal). A Diagnostic and Statistical Manual of Mental Disorders (DSM‐IV) diagnosis and information regarding mental health services were derived from the K‐SADS.

Results: Although ∼60% of the subjects had a DSM‐IV psychiatric diagnosis, >60% received no mental health treatment. Absence of mental health care was associated with younger age, less parental education, limited number of antiepileptic drugs (AEDs; i.e., one or none), and higher verbal IQ. In addition, children with PGE and a single psychiatric diagnosis were less likely to have a history of mental health treatment.

Conclusions: This is the first study to demonstrate unmet mental health need in a large sample of children with CPS and PGE. The study's findings suggest that parents and clinicians should be aware of the mental health needs of children with epilepsy, particularly if they have one or more of the identified risk factors.
Postictal Psychosis in Temporal Lobe Epilepsy
Authors: Leutmezer Fritz , Podreka Ivo , Asenbaum Susanne , Pietrzyk Uwe , Lucht Helmut , Back Claude , Benda Norbert , Baumgartner Christoph
Published: December 2004

Summary:  Purpose: Postictal psychosis is a well‐known complication, occurring especially in patients with temporal lobe epilepsy. It usually runs a benign course. The literature on this topic is sparse, and the underlying pathogenic mechanisms are not known.

Methods: We report five patients with temporal lobe epilepsy in whom postictal psychosis developed during the course of video‐EEG monitoring; they were studied with hexamethyl‐propyleneamine‐oxime single‐photon emission computed tomography (HMPAO‐SPECT) during and after the psychotic event.

Results: In comparison to the interictal state, all SPECT scans obtained during postictal psychosis were remarkable for bifrontal and bitemporal hyperperfusion patterns. Some studies also demonstrated unilateral left lateral frontal hyperperfusion. These cortical blood‐flow patterns appeared to be distinct from those obtained during complex partial seizures.

Conclusions: Our data suggest that postictal psychoses in patients with temporal lobe epilepsy are associated with hyperactivation of both temporal and frontal lobe structures. This hyperperfusion may reflect ongoing (subcortical) discharges, active inhibitory mechanisms that terminate the seizure, or simply a dysregulation of cerebral blood flow.
Heterogeneous Changes of Monophasic Action Potential Induced by Sustained Stretch in Atrium
Authors: BABUTY DOMINIQUE , LAB MAX
Published: December 2004

Atrial Monophasic Action Potential and Stretch. Introduction: Chronic enlargement of atrium is common in atrial fibrillation, and the effects of stretch on atrial action potentials seem inconsistent. As atrial muscle is heterogeneous, we suggest that atrial stretch induces a variable electrophysiologic response and that the effects of stretch are only partially mediated by stretch‐activated channels.

Methods and Results: Sixteen guinea pig hearts were perfused by the Langendorff method using Kreb's solution with and without 80 μM streptomycin, which is a stretch‐activated channel blocker. Suction electrodes were used to record monophasic action potentials (MAPs) of the left atrium. Left auricular pressure was monitored by a balloon. We determined the MAP duration at 50% and 90% repolarization (MAPD50 and MAPD90) in basal conditions and after a slow onset but sustained stretch of the atrium in the absence and presence of streptomycin. Stretch induced no overall consistent or significant change in mean MAPD50 and MAPD90. The individual responses were markedly variable. The most frequent response (about 50%) was a decrease in MAPD50 and MAPD90. In 25% of cases, there was no change, and in 25% we observed increases in MAPD50 and MAPD90. Streptomycin did not affect MAPD50 and MAPD90, but it dramatically modified the distribution of MAPD changes induced by stretch. In particular, streptomycin removed stretch‐induced shortening of MAPD50 and MAPD90, whereas it did not affect stretch‐induced lengthening.

Conclusion: Sustained stretch of atrium induces variable modifications of MAPD that are only partially inhibited by streptomycin. This suggests the participation of ionic channels other than specific stretch‐activated channels in the response of atrial myocardium to sustained stretch.
Interferometric Measurement in the Shock Tube of the Dissociation Rate of Oxygen
Authors: Matthews D. L.
Published: December 2004

The dissociation of oxygen has been observed behind shock waves at Mach numbers of 8 to 10, over a temperature range of 3000–5000°K. Photographs of the shocks were made using a Mach-Zehnder interferometer and a spark light source of effective duration 0.1 μsec. The velocity of the shock was measured using thin-film resistance thermometers to detect its passage. From this velocity and the state of the gas ahead of the shock, one can calculate the state of the gas behind the shock, both in the reaction zone and at equilibrium, from the interferometrically observed density ratios. Up to 12% equilibrium dissociation was obtained, following reaction zones of the order of 1 cm in length. The following rate constant, obtained from classical collision theory for the principal reaction O2+O2⇌ lim kD2O+O2,fitted the data well: kD = 7.4 × 1011PT½(59 380/T)3 exp (−59 380/T) cc mole−1 sec−1, where 59 380 is the known dissociation energy of oxygen, expressed in degrees Kelvin. The quantity P, the ``collision efficiency,'' was adjusted to fit the data, and was found to be 0.07. The data are consistent with the results of several other investigators who used different methods. The recombination rate constant calculated from the dissociation rate constant is 8.4 × 1014 cc2 mole−2 sec−1 at 3500°, and is approximately proportional to T−2.
Supersonic Nozzle Flow with a Reacting Gas Mixture
Authors: Wegener Peter P.
Published: December 2004

An investigation has been made of the stationary supersonic nozzle flow of a reacting gas mixture of nitrogen tetroxide and dioxide carried at low concentration in nitrogen. A judicious choice of supply conditions and nozzle geometry made it possible to produce flows either in chemical equilibrium or in states between this and the frozen flow. The flow could be fully determined from pressure and area measurements and, by applying an equation for the reaction mechanism, rate constants of recombination could be found. The results of these measurements agreed with those obtained from independent optical absorption measurements, and the third-order rate constant for recombination was found to be 3 × 1014 cm6 mole−2 sec−1 for 210 < T < 330°K. Finally, experiments with stationary oblique shocks led to a determination of the dissociation rate constant.
Confinement of Plasma by Standing Electromagnetic Wave
Authors: Cushing Vincent , Sodha Mahendra S.
Published: December 2004

In this paper the authors have discussed the confinement of plasma by a one-dimensional stationary electromagnetic wave. Their analysis is similar to that carried out by former workers for a TM0.1 mode but they have examined the assumptions limiting the applicability of present theories in detail. One of the conditions for the applicability of the present theory is that the frequency of the electromagnetic wave should be of the same order or greater than the plasma frequency at the nodes where particle density is maximum. This condition makes the present theories nonapplicable in cases of thermonuclear interest.