bluuebunny/crossref_metadata_2025_split huggingface dataset:
Presynaptic quantal plasticity: Katz's original hypothesis revisited
Authors: Vautrin Jean , Barker Jeffery L. 
Published: December 2002

AbstractChanges in the amplitudes of signals conveyed at synaptic contacts between neurons underlie many brain functions and pathologies. Here we review the possible determinants of the amplitude and plasticity of the elementary postsynaptic signal, the miniature. In the absence of a definite understanding of the molecular mechanism releasing transmitters, we investigated a possible alternative interpretation. Classically, both the quantal theory and the vesicle theory predict that the amount of transmitter producing a miniature is determined presynaptically prior to release and that rapid changes in miniature amplitude reflect essentially postsynaptic alterations. However, recent data indicates that short‐term and long‐lasting changes in miniature amplitude are in large part due to changes in the amount of transmitter in individual released packets that show no evidence of preformation. Current representations of transmitter release derive from basic properties of neuromuscular transmission and endocrine secretion. Reexamination of overlooked properties of these two systems indicate that the amplitude of miniatures may depend as much, if not more, on the Ca2+ signals in the presynaptic terminal than on the number of postsynaptic receptors available or on vesicle's contents. Rapid recycling of transmitter and its possible adsorption at plasma and vesicle lumenal membrane surfaces suggest that exocytosis may reflect membrane traffic rather than actual transmitter release. This led us to reconsider the disregarded hypothesis introduced by Fatt and Katz (1952; J Physiol 117:109–128) that the excitability of the release site may account for the “quantal effect” in fast synaptic transmission. In this case, changes in excitability of release sites would contribute to the presynaptic quantal plasticity that is often recorded. Synapse 47:184–199, 2003. © 2002 Wiley‐Liss, Inc.
The mGluR5 antagonist MPEP reduces the conditioned rewarding effects of cocaine but not other drugs of abuse
Authors: McGeehan Andrew J. , Olive M. Foster 
Published: December 2002

AbstractWe examined the ability of 2‐methyl‐6‐(phenylethynyl)‐pyridine (MPEP), a selective antagonist of the type 5 metabotropic glutamate receptor (mGluR5), to reduce the rewarding effects of various drugs of abuse in the conditioned place preference (CPP) paradigm. Mice were treated with MPEP (1, 5, and 20 mg/kg i.p.) 10 min prior to cocaine (15 mg/kg i.p.), D‐amphetamine (2 mg/kg i.p.), nicotine (0.5 mg/kg i.p.), morphine (5 mg/kg i.p.), or ethanol (2 g/kg i.p.) on 3 successive days of CPP conditioning trials. MPEP pretreatment dose‐dependently reduced the development of CPP for cocaine only. When tested alone at the doses effective in reducing CPP, MPEP produced neither a place preference nor aversion. These data provide further support for a role of the mGluR5 receptor in the rewarding effects of cocaine. Synapse 47:240–242, 2003. © 2002 Wiley‐Liss, Inc.
Effect of isolation rearing on pre‐ and post‐synaptic serotonergic function in the rat dorsal hippocampus
Authors: Muchimapura Suparporn , Mason Robert , Marsden Charles A. 
Published: December 2002

AbstractSeveral behavioural, neurochemical, and structural alterations found in isolation‐reared rats are similar to those in human schizophrenia. This study investigated changes in cholinergic and serotonergic function in the hippocampus following isolation rearing. Rats were reared in social isolation from weaning for 6 weeks before study and compared to group‐reared rats. An in vitro electrophysiological study investigated the effect of isolation rearing on postsynaptic 5‐HT1A function on CA1 hippocampal neurones activated with the muscarinic agonist carbachol and found no change in the sensitivity of these postsynaptic receptors between the groups. However, a change in presynaptic function was identified, as there was a significant reduction in the time taken for neuronal firing to recover to 50% of the original rate following 5‐HT (10 μM) application, in isolation compared to group‐reared rats. These data suggest a possible change in reuptake following isolation. Uptake studies using 3[H]5‐HT, however, found no change in the inhibition of uptake produced by either fluoxetine or paroxetine in isolation compared to group‐reared rats. The selective 5‐HT1B antagonist CP‐294253 (1 μM), increased endogenous 5‐HT release from hippocampal slices in vitro and this effect was greater (P < 0.001) in group compared to isolation‐reared rats. These results indicate that the change in presynaptic 5‐HT neuronal function was due to impaired autoreceptor responsiveness. Carbachol (1 μM) increased the firing rate of all neurones recorded but only a proportion of these showed a concentration‐related increase. Isolation rearing increased the sensitivity of neurones, showing a concentration‐related increase in firing in response to carbachol, but had no effect on the other neurones. In summary, the present study showed that isolation rearing alters presynaptic 5‐HT1B but not postsynaptic 5‐HT1A receptor activity in the hippocampus. Isolation rearing in the rat results in hippocampal dysfunction, including reduced serotonergic and enhanced muscarinic activity of some neurones. These effects may in part underlie the behavioural consequences of isolation relevant to human developmental disorders. Synapse 47:209–217, 2003. © 2002 Wiley‐Liss, Inc.
Increased dopamine D3 receptor expression accompanying behavioral sensitization to nicotine in rats
Authors: Le Foll Bernard , Diaz Jorge , Sokoloff Pierre 
Published: December 2002

AbstractBehavioral sensitization to nicotine, which appears following repeated nicotine administration, has been suggested to take part in the development of smoking habit in humans. The mesolimbic dopaminergic system plays a role in this process and a hypersensitivity of postsynaptic neurons of the nucleus accumbens as been proposed as a mechanism, but changes in dopamine D1 or D2 receptors have not been demonstrated to date. A challenge administration of nicotine (0.5 mg/kg s.c.) produced a strong increase in locomotor activity in rats repeatedly pretreated with nicotine (0.5 mg/kg sc), but not saline, once a day for 5 days. This behavioral sensitization was accompanied by an increase in D3 receptor binding and mRNA in the shell of nucleus accumbens. D3 receptor expression was unchanged in the core of nucleus accumbens and dorsal striatum, as it was in the shell of nucleus accumbens after an acute administration of nicotine to naive rats. In contrast, no changes were noticed in D1 and D2 receptor expressions in any brain region examined after chronic or acute treatment with nicotine. In addition, nicotine challenge decreased preprodynorphin and preprotachykinin mRNA levels in naive rats, but only preprotachykinin mRNA levels in rats pretreated with nicotine. These biochemical changes resemble those occurring during behavioral sensitization to levodopa of dopamine‐denervated rats, which had been causally related to the induction of D3 receptor expression. We propose that a similar mechanism is responsible for behavioral sensitization to nicotine. Synapse 47:176–183, 2003. © 2002 Wiley‐Liss, Inc.
The stability of a slowly diverging swirling jet
Authors: COOPER A. J. , PEAKE N. 
Published: December 2002

The spatial evolution of small-amplitude unsteady disturbances of an axisymmetric
swirling jet is examined theoretically. The slow axial divergence of the jet mean flow
is accounted for by using the method of multiple scales and a consistent solution
for both the mean flow and unsteady disturbance is derived. Previous work by Lu &
Lele (1999) has considered the leading-order analysis, in which the modal eigenvalues
are determined from locally parallel theory, but the key feature of our analysis is
the solution of the next-order secularity condition for the axial variation of the
wave-envelope amplitude.The swirling jet profile sustains two types of instability waves: the Kelvin–Helmholtz
instability associated with axial shear, and a centrifugal instability which arises due
to a decrease in circulation with radial distance. The evolution of the disturbance
axial wavenumber and envelope amplitude with downstream distance is calculated.
Numerical results show that the growth of the centrifugal mode is significantly
curtailed as a result of a rapidly decaying envelope amplitude. The shear instability
is significantly more amplified by the addition of swirl.The general solution for the disturbance envelope amplitude breaks down at so-called
turning points. This is found to occur for a series of neutral propagating modes.
A rescaling in the vicinity of the turning point shows that the amplitude in this region
is governed by a parabolic cylinder equation. The modal amplitude is seen to decay
very significantly through this turning point, even though the mode is neutral to
leading order.
Nutrition in terrestrial isopods (Isopoda: Oniscidea): an evolutionary‐ecological approach
Authors: ZIMMER MARTIN 
Published: December 2002

ABSTRACTThe nutritional morphology, physiology and ecology of terrestrial isopods (Isopoda: Oniscidea) is significant in two respects. (1) Most oniscid isopods are truly terrestrial in terms of being totally independent of the aquatic environment. Thus, they have evolved adaptations to terrestrial food sources. (2) In many terrestrial ecosystems, isopods play an important role in decomposition processes through mechanical and chemical breakdown of plant litter and by enhancing microbial activity. While the latter aspect of nutrition is discussed only briefly in this review, I focus on the evolutionary ecology of feeding in terrestrial isopods.Due to their possessing chewing mouthparts, leaf litter is comminuted prior to being ingested, facilitating both enzymatic degradation during gut passage and microbial colonization of egested faeces. Digestion of food through endogenous enzymes produced in the caeca of the midgut glands (hepatopancreas) and through microbial enzymes, either ingested along with microbially colonized food or secreted by microbial endosymbionts, mainly takes place in the anterior part of the hindgut. Digestive processes include the activity of carbohydrases, proteases, dehydrogenases, esterases, lipases, arylamidases and oxidases, as well as the nutritional utilization of microbial cells. Absorption of nutrients is brought about by the hepatopancreas and/or the hindgut epithelium, the latter being also involved in osmoregulation and water balance. Minerals and metal cations are effectively extracted from the food, while overall assimilation efficiencies may be low. Heavy metals are stored in special organelles of the hepatopancreatic tissue. Nitrogenous waste products are excreted via ammonia in its gaseous form, with only little egested along with the faeces. Nonetheless, faeces are characterized by high nitrogen content and provide a favourable substrate for microbial colonization and growth. The presence of a dense microbial population on faecal material is one reason for the coprophagous behaviour of terrestrial isopods. For the same reason, terrestrial isopods prefer feeding on decaying rather than fresh leaf litter, the former also being more palatable and easier to digest. Acceptable food sources are detected through distance and contact chemoreceptors. The ‘quality’ of the food source determines individual growth, fecundity and mortality, and thus maintenance at the population level. Due to their physiological adaptations to feeding on and digesting leaf litter, terrestrial isopods contribute strongly to nutrient recycling during decomposition processes. Yet, many of these adaptations are still not well understood.
Haeckel's ABC of evolution and development
Authors: RICHARDSON MICHAEL K. , KEUCK GERHARD 
Published: December 2002

ABSTRACTOne of the central, unresolved controversies in biology concerns the distribution of primitiveversusadvanced characters at different stages of vertebrate development. This controversy has major implications for evolutionary developmental biology and phylogenetics. Ernst Haeckel addressed the issue with his Biogenetic Law, and his embryo drawings functioned as supporting data. We re‐examine Haeckel's work and its significance for modern efforts to develop a rigorous comparative framework for developmental studies. Haeckel's comparative embryology was evolutionary but non‐quantitative. It was based on developmental sequences, and treated heterochrony as a sequence change. It is not always clear whether he believed in recapitulation of single characters or entire stages. The Biogenetic Law is supported by several recent studies ‐ if applied to single characters only. Haeckel's important but overlooked alphabetical analogy of evolution and development is an advance on von Baer. Haeckel recognized the evolutionary diversity in early embryonic stages, in line with modern thinking. He did not necessarily advocate the strict form of recapitulation and terminal addition commonly attributed to him. Haeckel's much‐criticized embryo drawings are important as phylogenetic hypotheses, teaching aids, and evidence for evolution. While some criticisms of the drawings are legitimate, others are more tendentious. In opposition to Haeckel and his embryo drawings, Wilhelm His made major advances towards developing a quantitative comparative embryology based on morphometrics. Unfortunately His's work in this area is largely forgotten. Despite his obvious flaws, Haeckel can be seen as the father of a sequence‐based phylogenetic embryology.
Sexual selection: an evolutionary force in plants?
Authors: SKOGSMYR IO , LANKINEN ÅSA 
Published: December 2002

ABSTRACTSexual selection has traditionally been used to explain exaggerated sexual traits in male animals. Today the concept has been developed and various other sexually related traits have been suggested to evolve in the same manner. In nearly all new areas where the theory of sexual selection has been applied, there has been an intense debate as to whether the application is justified. Is it the case that some scientists are all too ready to employ fashionable ideas? Or are there too many dogmatic researchers refusing to accept that science develops and old ideas are transformed? Maybe the controversies are simply a reflection of the difficulty of defining a theory under constant re‐evaluation. Thus, we begin by summarizing the theory of sexual selection in order to assess the influence of sexual selection on the evolution of plant morphology. We discuss empirical findings concerning potentially affected traits. Although we have tried to address criticisms fairly, we still conclude that sexual selection can be a useful tool when studying the evolution of reproductive traits in plants. Furthermore, by including the evidence from an additional kingdom, a fuller understanding of the processes involved in sexual selection can be gained.
Nitric oxide and changes of iron metabolism in exercise
Authors: QIAN ZHONG MING 
Published: December 2002

ABSTRACTAccumulated data imply that exercise itself might not lead to a true iron deficiency or ‘sport anaemia’ in a healthy athlete who has adequate iron intake. The higher prevalence of iron deficiency anaemia in younger female athletes might be not due to exercise itself, but probably results from dietary choices, inadequate iron intake and menstruation. These factors can also induce iron deficiency or anaemia in the general population. However, exercise does affect iron metabolism, leading to low or sub‐optimal iron status. The underlying mechanism is unknown. In this review, recent advances in the study of the effect of exercise on iron metabolism and nitric oxide, and the relationship between nitric oxide and iron status in exercise are discussed. A hypothesis that increased production of nitric oxide might contribute to sub‐optimal iron status in exercise is proposed.
Memory trace in prefrontal cortex: theory for the cognitive switch
Authors: OTANI SATORU 
Published: December 2002

ABSTRACTThe dorsolateral prefrontal cortex in human and non‐human primates functions as the highest‐order executor for the perception‐action cycle. According to this view, when perceptual stimuli from the environment are novel or complex, the dorsolateral prefrontal cortex serves to set consciously a goal‐directed scheme which broadly determines an action repertory to meet the particular demand from the environment. In this respect, the dorsolateral prefrontal cortex is a short‐term activation device with the properties of a ‘cognitive switch’, because it couples a particular set of perceptual stimuli to a particular set of actions. Here, I suggest that, in order for the organism to react systematically to the environment, neural traces for the switch function must be stored in the brain. Thus, the highest‐order, perception‐action interface function of the dorsolateral prefrontal cortex per se depends on permanently stored neural traces in the dorsolateral prefrontal cortex and related structures. Such a memory system may be located functionally between two of the well‐documented memory systems in the brain: the declarative memory system and the procedural memory system. Finally, based on available neurophysiological data, the possible mechanisms underlying the formation of cognitive switch traces are proposed.
Generation of
Helicobacter pylori
Ghosts by PhiX Protein E-Mediated Inactivation and Their Evaluation as Vaccine Candidates
Authors: Panthel Klaus , Jechlinger Wolfgang , Matis Alexander , Rohde Manfred , Szostak Michael , Lubitz Werner , Haas Rainer 
Published: December 2002

ABSTRACT

Bacterial ghosts are empty cell envelopes, which may be generated by the controlled expression of the PhiX174 lysis gene
E
in gram-negative bacteria to obtain vaccine candidates. We describe here the application of this technology to
Helicobacter pylori
. The lysis gene cassette was cloned into an
Escherichia coli-Helicobacter pylori
shuttle vector and introduced into an
H. pylori
recipient strain by bacterial conjugation. Temperature induction of the lysis gene cassette revealed a quantitative killing of the
H. pylori
culture without induction of lysis-resistant bacteria. Biochemical and transmission electron microscopic studies identified structurally intact
H. pylori.
Prophylactic oral vaccination experiments using these
H. pylori
ghosts in the BALB/c mouse model showed a significant reduction of the bacterial load in the ghost group, as measured by a quantitative bacterial reisolation procedure. Ten of 10 and 5 of 10 mice were protected, respectively, without the use of a mucosal adjuvant. Coadministration of ghosts with cholera toxin as mucosal adjuvant resulted in a complete protection of 10 of 10 and 8 of 8 mice against
H. pylori
challenge, with three animals showing a sterile immunity.
Multigenic Control of Disease Severity after VirulentMycobacterium tuberculosisInfection in Mice
Authors: Sánchez Fabio , Radaeva Tatiana V. , Nikonenko Boris V. , Persson Ann-Sophie , Sengul Selim , Schalling Martin , Schurr Erwin , Apt Alexander S. , Lavebratt Catharina 
Published: December 2002

ABSTRACTFollowing challenge with virulentMycobacterium tuberculosis, mice of the I/St inbred strain exhibit shorter survival time, more rapid body weight loss, higher mycobacterial loads in organs, and more severe lung histopathology than mice of the A/Sn strain. We previously performed a genome-wide scan for quantitative trait loci (QTLs) that control the severity ofM. tuberculosis-triggered disease in [(A/Sn × I/St) F1 × I/St] backcross-1 (BC1) mice and described several QTLs that are significantly or suggestively linked to body weight loss. In the present study we expanded our analysis by including the survival time phenotype and by genotyping 406 (A/Sn × I/St) F2 mice for the previously identified chromosomal regions of interest. The previously identified 12-cM-wide QTL on distal mouse chromosome 3 was designatedtbs1(tuberculosisseverity1); the location of the QTL on proximal chromosome 9 was narrowed to a 9-cM interval, and this QTL was designatedtbs2. Allelic variants of thetbs2locus appeared to be involved in control of both body weight loss and survival time. Also, the data strongly suggested that a QTL located in the vicinity of theH-2complex on chromosome 17 is involved in control of tuberculosis in mice of both genders, whereas thetbs1locus seemed to have an effect on postinfection body weight loss in female mice. Interestingly, these loci appeared to interact with each other, which suggests that there might be a basic genetic network for the control of intracellular parasites. Overall, linkage data reported here for F2 mice are in agreement with, and add to, our previous findings concerning the control ofM. tuberculosis-triggered disease in the BC1 segregation.
Fibronectin Bound to the Surface of
Staphylococcus aureus
Induces Association of Very Late Antigen 5 and Intracellular Signaling Factors with Macrophage Cytoskeleton
Authors: Shinji Hitomi , Seki Keiko , Tajima Akiko , Uchida Atsuko , Masuda Shogo 
Published: December 2002

ABSTRACT

Staphylococcus aureus
Cowan I and a clinically isolated coagulase-negative
Staphylococcus
strain,
S. saprophyticus
10312, were found to have two fibronectin binding proteins, FnBPA and FnBPB. While both staphylococci bound to serum fibronectin to a similar extent, fibronectin binding significantly increased the phagocytic activity of macrophages against
S. aureus
(by ca. 150%) but not against
S. saprophyticus
. This enhancing effect of fibronectin was inhibited by an RGD sequence-containing peptide and also by anti-very late antigen 5 antibody. This suggests that the effect is mediated by very late antigen 5 expressed on macrophages. In macrophages ingesting fibronectin-bound Cowan I, α
5
and β
1
chains were associated with the cytoskeleton. Cytosolic signaling factors such as paxillin, c-Src, and c-Csk were also associated with the cytoskeleton. On the contrary, β
3
integrin transiently disappeared from the cytoskeleton when macrophages ingested the fibronectin-treated
S. aureus
Cowan I. Furthermore, the Src kinase family tyrosine kinase Lyn dissociated from the cytoskeleton. These cellular components did not respond in a fibronectin-dependent manner when macrophages phagocytosed
S. saprophyticus
. This means that only fibronectin-treated
S. aureus
Cowan I induces the accumulation of very late antigen 5, which in turn induces the association of paxillin and tyrosine kinases. It is thought that the phagocytic activity of macrophages against fibronectin-treated
S. aureus
was increased by signaling via the activation of very late antigen 5.
Lipooligosaccharide-DeficientNeisseria meningitidisShows Altered Pilus-Associated Characteristics
Authors: Albiger Barbara , Johansson Linda , Jonsson Ann-Beth 
Published: December 2002

ABSTRACTMolecular interaction between host mucosal surfaces and outer membrane components of microbes is crucial in the infection process. The outer membrane of pathogenicNeisseriacontains surface molecules such as pili, PilC, and Opa and a monolayer of lipooligosaccharide (LOS), all of which are involved in the interaction with host cells. Pili mediate the initial attachment to human epithelial cells, which is followed by tight contact between bacteria and the eucaryotic cells, leading to bacterial invasion. To further examine the basis for bacterium-host cell contact, we constructed an LOS-deficientNeisseria meningitidisserogroup C mutant. LOS deficiency was without exception accompanied by altered colony opacity and morphology, which most likely represented an “on” switch for Opa540 expression, and by reduced levels of the iron-regulated proteins FetA and FbpA. We show here that LOS is essential for pilus-associated adherence but dispensable for fiber formation and twitching motility. The absence of attachment to epithelial cells could not be attributed to altered levels of piliation or defects in the pilus adhesion phenotype. Further, LOS mutants do not invade host cells and have lost the natural competence for genetic transformation.