bluuebunny/crossref_metadata_2025_split huggingface dataset:
Group I mGluR5 metabotropic glutamate receptors regulate proliferation of neuronal progenitors in specific forebrain developmental domains
Authors: Gandhi Rina , Luk Kelvin C. , Rymar Vladimir V. , Sadikot Abbas F. 
Published: October 2007

AbstractMajor classical neurotransmitters including GABA and glutamate play novel morphogenic roles during development of the mammalian CNS. During forebrain neurogenesis, glutamate regulates neuroblast proliferation in different germinal domains using receptor subtype‐specific mechanisms. For example, ionotropic N‐methyl‐D‐aspartate (NMDA) or alpha‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazole propionic acid (AMPA) glutamate receptors mediate distinct proliferative effects in ventral or dorsal forebrain germinal domains, and regulate the correct number of neurons that populate the striatum or cerebral cortex. Recent work suggests metabotropic receptors may also mediate glutamate’s proliferative effects. Group I mGluR5 receptor subtypes are highly expressed in forebrain germinal zones. Using in vitro and in vivo methods, we demonstrate mGluR5 receptor activation plays an important role in neuroblast proliferation in the ventral telencephalon, and helps determine the complement of striatum projection neurons. mGluR5 receptor‐mediated effects on striatal neuronal progenitors are restricted mainly to early cycling populations in the ventricular zone, with little effect on secondary proliferative populations in the subventricular zone. In contrast to proliferative effects in the ventral telencephalon, mGluR5 receptors do not modulate proliferation of dorsal telencephalon‐derived cortical neuroblasts. Heterogeneous domain‐specific proliferative effects of glutamate‐mediated by specific receptor subtypes provide an important developmental mechanism allowing generation of the correct complement of neuronal subtypes that populate the mammalian forebrain.
CB1 knockout mice display impaired functionality of 5‐HT1A and 5‐HT2A/C receptors
Authors: Mato Susana , Aso Ester , Castro Elena , Martín Miquel , Valverde Olga , Maldonado Rafael , Pazos Ángel 
Published: October 2007

AbstractInteraction between brain endocannabinoid (EC) and serotonin (5‐HT) systems was investigated by examining 5‐HT‐dependent behavioral and biochemical responses in CB1 receptor knockout mice. CB1 knockout animals exhibited a significant reduction in the induction of head twitches and paw tremor by the 5‐HT2A/C receptor selective agonist (±) DOI, as well as a reduced hypothermic response following administration of the 5‐HT1A receptor agonist (±)‐8‐OH‐DPAT. Additionally, exposure to the tail suspension test induced enhanced despair responses in CB1 knockout mice. However, the tricyclic antidepressant imipramine and the 5‐HT selective reuptake inhibitor fluoxetine induced similar decreases in the time of immobility in the tail suspension test in CB1 receptor knockout and wild‐type mice. No differences were found between both genotypes with regard to 5‐HT2A receptor and 5‐HT1A receptors levels, measured by autoradiography in different brain areas. However, a significant decrease in the ability of both, the 5‐HT1A receptor agonist (±)‐8‐OH‐DPAT and the 5‐HT2A/C receptor agonist (−)DOI, to stimulate [35S]GTPγS binding was detected in the hippocampal CA1 area and fronto‐parietal cortex of CB1 receptor knockout mice, respectively. This study provides evidence that CB1 receptors are involved in the regulation of serotonergic responses mediated by 5‐HT2A/C and 5‐HT1A receptors, and suggests that a reduced coupling of 5‐HT1A and 5‐HT2A receptors to G proteins might be involved in these effects.
The coexistence of multiple receptors in a single nerve terminal provides evidence for pre‐synaptic integration
Authors: Ladera Carolina , Godino María del Carmen , Martín Ricardo , Luján Rafael , Shigemoto Ryuichi , Ciruela Francisco , Torres Magdalena , Sánchez‐Prieto José 
Published: October 2007

AbstractExcitatory synaptic transmission is inhibited by G protein coupled receptors, including the adenosine A1, GABAB, and metabotropic glutamate receptor 7. These receptors are present in nerve terminals where they reduce the release of glutamate through activating signaling pathways negatively coupled to Ca2+ channels and adenylyl cyclase. However, it is not clear whether these receptors operate in distinct subpopulations of nerve terminals or if they are co‐expressed in the same nerve terminals, despite the functional consequences that such distributions may have on synaptic transmission. Applying Ca2+ imaging and immunocytochemistry, we show that these three G protein coupled receptors coexist in a subpopulation of cerebrocortical nerve terminals. The three receptors share an intracellular signaling pathway through which their inhibitory responses are integrated and coactivation of these receptors produced an integrated response. Indeed, this response was highly variable, from a synergistic response at subthreshold agonist concentrations to an occluded response at high agonist concentrations. The presence of multiple receptors in a nerve terminal could be responsible for the physiological effects of neurotransmitter spillover from neighboring synapses or alternatively, the co‐release of transmitters by the same nerve terminal.
Monocyte chemoattractant protein‐1 functions as a neuromodulator in dorsal root ganglia neurons
Authors: Jung Hosung , Toth Peter T. , White Fletcher A. , Miller Richard J. 
Published: October 2007

AbstractIt has previously been observed that expression of chemokine monocyte chemoattractant protein‐1 (MCP‐1/CC chemokine ligand 2 (CCL2)) and its receptor CC chemokine receptor 2 (CCR2) is up‐regulated by dorsal root ganglion (DRG) neurons in association with rodent models of neuropathic pain. MCP‐1 increases the excitability of nociceptive neurons after a peripheral nerve injury, while disruption of MCP‐1/CCR2 signaling blocks the development of neuropathic pain, suggesting MCP‐1 signaling is responsible for heightened pain sensitivity. To define the mechanisms of MCP‐1 signaling in DRG, we studied intracellular processing, release, and receptor‐mediated signaling of MCP‐1 in DRG neurons. We found that in a focal demyelination model of neuropathic pain both MCP‐1 and CCR2 were up‐regulated by the same neurons including transient receptor potential vanilloid receptor subtype 1 (TRPV1) expressing nociceptors. MCP‐1 expressed by DRG neurons was packaged into large dense‐core vesicles whose release could be induced from the soma by depolarization in a Ca2+‐dependent manner. Activation of CCR2 by MCP‐1 could sensitize nociceptors via transactivation of transient receptor potential channels. Our results suggest that MCP‐1 and CCR2, up‐regulated by sensory neurons following peripheral nerve injury, might participate in neural signal processing which contributes to sustained excitability of primary afferent neurons.
DNA barcode discovers two cryptic species and two geographical radiations in the invasive drosophilid Zaprionus indianus
Authors: YASSIN AMIR , CAPY PIERRE , MADI‐RAVAZZI LILIAN , OGEREAU DAVID , DAVID JEAN R. 
Published: October 2007

AbstractComparing introduced to ancestral populations within a phylogeographical context is crucial in any study aiming to understand the ecological genetics of an invasive species. Zaprionus indianus is a cosmopolitan drosophilid that has recently succeeded to expand its geographical range upon three continents (Africa, Asia and the Americas). We studied the distribution of mitochondrial DNA (mtDNA) haplotypes for two genes (CO‐I and CO‐II) among 23 geographical populations. mtDNA revealed the presence of two well‐supported phylogenetic lineages (phylads), with bootstrap value of 100%. Phylad I included three African populations, reinforcing the African‐origin hypothesis of the species. Within phylad II, a distinct phylogeographical pattern was discovered: Atlantic populations (from the Americas and Madeira) were closer to the ancestral African populations than to Eastern ones (from Madagascar, Middle East and India). This means that during its passage from endemism to cosmopolitanism, Z. indianus exhibited two independent radiations, the older (the Eastern) to the East, and the younger (the Atlantic) to the West. Discriminant function analysis using 13 morphometrical characters was also able to discriminate between the two molecular phylads (93.34 ± 1.67%), although detailed morphological analysis of male genitalia using scanning electron microscopy showed no significant differences. Finally, crossing experiments revealed the presence of reproductive barrier between populations from the two phylads, and further between populations within phylad I. Hence, a bona species status was assigned to two new, cryptic species: Zaprionus africanus and Zaprionus gabonicus, and both were encompassed along with Z. indianus and Zaprionus megalorchis into the indianus complex. The ecology of these two species reveals that they are forest dwellers, which explains their restricted endemic distribution, in contrast to their relative cosmopolitan Z. indianus, known to be a human‐commensal. Our results reconfirm the great utility of mtDNA at both inter‐ and intraspecific analyses within the frame of an integrated taxonomical project.
The age of Rubisco: the evolution of oxygenic photosynthesis
Authors: NISBET E. G. , GRASSINEAU N. V. , HOWE C. J. , ABELL P. I. , REGELOUS M. , NISBET R. E. R. 
Published: October 2007

ABSTRACTThe evolutionary history of oxygenesis is controversial. Form I of ribulose 1,5‐bisphosphate carboxylase/oxygenase (Rubisco) in oxygen‐tolerant organisms both enables them to carry out oxygenic extraction of carbon from air and enables the competitive process of photorespiration. Carbon isotopic evidence is presented from ~2.9 Ga stromatolites from Steep Rock, Ontario, Canada, ~2.9 Ga stromatolites from Mushandike, Zimbabwe, and ~2.7 Ga stromatolites in the Belingwe belt, Zimbabwe. The data imply that in all three localities the reef‐building autotrophs included organisms using Form I Rubisco. This inference, though not conclusive, is supported by other geochemical evidence that these stromatolites formed in oxic conditions. Collectively, the implication is that oxygenic photosynthesizers first appeared ~2.9 Ga ago, and were abundant 2.7–2.65 Ga ago.Rubisco specificity (its preference for CO2 over O2) and compensation constraints (the limits on carbon fixation) may explain the paradox that despite the inferred evolution of oxygenesis 2.9 Ga ago, the Late Archaean air was anoxic. The atmospheric CO2:O2 ratio, and hence greenhouse warming, may reflect Form I Rubisco's specificity for CO2 over O2. The system may be bistable under the warming Sun, with liquid oceans occurring in either anoxic (H2O with abundant CH4 plus CO2) or oxic (H2O with more abundant CO2, but little CH4) greenhouse states. Transition between the two states would involve catastrophic remaking of the biosphere. Build‐up of a very high atmospheric inventory of CO2 in the 2.3 Ga glaciation may have allowed the atmosphere to move up the CO2 compensation line to reach stability in an oxygen‐rich system. Since then, Form I Rubisco specificity and consequent compensation limits may have maintained the long‐term atmospheric disproportion between O2 and CO2, which is now close to both CO2 and O2 compensation barriers.
Protein translation, 2007
Authors: Kaeberlein Matt , Kennedy Brian K. 
Published: October 2007

SummaryTranslation of RNA to protein is essential for life. It should perhaps not be surprising, therefore, that appropriate regulation of translation plays a key role in determining longevity. This Hot Topic article discusses papers published in the last year related to the importance of translation and its regulation by signaling through the target of rapamycin kinase, in modulating aging and age‐associated diseases.
Technical Note: Grading the vertical cup:disc ratio and the effect of scaling
Authors: Bennett Ruth , Spry Paul G. D. , Fenerty Cecilia H. , Harper Robert A. 
Published: October 2007

AbstractPurpose:  To evaluate the effect of scaling on sensitivity to change for grading the vertical cup:disc ratio (CDR).Methods:  Vertical CDR was assessed by six observers (three ophthalmologists and three optometrists) on 43 stereo disc photographs. Repeated observations were made for both 0.1 and 0.05 interval scales. Paired differences were calculated for all observers and each observer separately. Mean and standard deviation of differences and agreement statistics were used to compare scales.Results:  Five observers demonstrated a reduction in the spread of differences (mean difference 0.19 to 0.15) and all observers demonstrated a reduction in concordance using the finer scale (mean concordance 54% to 39%).Conclusion:  The use of a finer scale reduces test–retest variability and increases sensitivity to change when estimating the vertical CDR. Use of this scale does not require any additional resource and it may be easily implemented in routine clinical practice.
Guest Editorial: A brief history of trichromacy
Authors: Weale Robert 
Published: October 2007

Abstract2007 is the bicentenary year of the publication of Thomas Young’s theory of colour vision. Ideas on trichromacy are traced here from the seventeenth to the twentieth century, and some of the chief protagonists (and antagonists) involved are mentioned. Reference is made to an early (1613) trichromatically‐generated grey. Attention is paid also to the international dimension of the subject.
Discontinuity of Coverage for Medicaid and S‐CHIP Children at a Transitional Birthday
Authors: Ketsche Patricia , Adams E. Kathleen , Snyder Angela , Zhou Mei , Minyard Karen , Kellenberg Rebecca 
Published: October 2007

Research Objective. To investigate disenrollment from public insurance at the 6‐year transitional birthday when eligibility for many children moves from Medicaid to State Children's Health Insurance Program (S‐CHIP).Data Sources. Data from Georgia's S‐CHIP (PeachCare) and Medicaid programs from 2000 to 2002.Study Design. The likelihood of dropping public coverage after the reference birthday is modeled for children turning age 6 compared with a control cohort of children turning age 9 controlling for demographic and geographic differences between enrollees.Principal Findings. Over 17 percent of 6‐year‐olds versus only 7 percent of the control cohort dropped coverage. After controlling for other factors (e.g., race/ethnicity, prior enrollment, and geographic region) having lower historical expenditures is predictive of dropping coverage among all children, although the unadjusted effect is stronger among children enrolled in PeachCare before their sixth birthday. Only 1 percent of Medicaid children who remained covered transitioned to PeachCare.Conclusions. Turnover at transitional birthdays identifies a common pathway for children into the ranks of the uninsured. Facilitating continuous enrollment would retain in the programs children with lower than average expenditures. This may be one of the more cost effective ways of reducing the number of uninsured children in Georgia.
Diffusion‐based magnetic resonance imaging and tractography in epilepsy
Authors: Yogarajah Mahinda , Duncan John S. 
Published: October 2007

Summary Diffusion‐based imaging is an advanced MRI technique that is sensitive to the movement of water molecules, providing additional information on the micro‐structural arrangement of tissue. Qualitative and quantitative analysis of peri, post and interictal diffusion images can aid the localization of seizure foci. Diffusion tensor tractography is an extension of diffusion‐based imaging, and can provide additional information about white matter pathways. Both techniques are able to increase understanding of the effects of epilepsy on the structural organization of the brain, and can be used to optimize presurgical planning of patients with epilepsy. This review focuses on the basis, applications, limitations, and future directions of diffusion imaging in epilepsy. Literature search strategy: We searched Pubmed using the terms “diffusion MRI or diffusion tensor MRI or tractography and epilepsy.”
Calorie‐restricted ketogenic diet increases thresholds to all patterns of pentylenetetrazol‐induced seizures: Critical importance of electroclinical assessment
Authors: Raffo Emmanuel , François Jennifer , Ferrandon Arielle , Koning Estelle , Nehlig Astrid 
Published: October 2007

SummaryPurpose:Thresholds to pentylenetetrazol (PTZ) seizures were usually based only on clinical symptoms. Our purpose was to use electroclinical patterns to assess the efficacy of a ketogenic and/or calorie‐restricted diet on PTZ‐induced seizures.Methods:Forty 50‐day‐old rats were divided in four weight‐matched groups and fed controlled diets: normocalorie carbohydrate (NC), hypocalorie carbohydrate (HC), normocalorie ketogenic (NK), and hypocalorie ketogenic (HK). After 21 days, blood glucose and β‐hydroxybutyrate levels were determined and seizures were induced by continuous infusion of PTZ. The clinical and EEG thresholds to each seizure pattern were compared between the different groups.Results:The electroclinical course of PTZ‐induced seizures was similar in all groups. The HK group exhibited higher thresholds than the other ones for most clinical features: absence (p = 0.003), first overt myoclonia (p = 0.028), clonic seizure (p = 0.006), and for EEG features: first spike (p = 0.036), first spike‐and‐wave discharge (p = 0.014), subcontinuous spike‐and‐wave discharges (p = 0.005). NK, HC, and NC groups were not significantly different from each other. Blood glucose and β‐hydroxybutyrate levels were not correlated with electroclinical seizure thresholds. After the clonic seizure, despite stopping PTZ infusion, a tonic seizure occurred in some animals, without significant difference regarding the diet.Conclusion:This approach permitted a precise study of the electroclinical course of PTZ‐induced seizures. In addition to the usually studied first overt myoclonia, we clearly demonstrated the efficiency of a calorie restricted KD in elevating thresholds to most electroclinical seizure patterns. We confirmed the lack of efficiency of the KD to reduce seizure severity once the seizure has started.
EEG source localization in focal epilepsy: Where are we now?
Authors: Plummer Chris , Harvey A. Simon , Cook Mark 
Published: October 2007

Summary Electroencephalographic source localization (ESL) by noninvasive means is an area of renewed interest in clinical epileptology. This has been driven by innovations in the computer‐assisted modeling of dipolar and distributed sources for the investigation of focal epilepsy; a process fueled by the ever‐increasing computational power available to researchers for the analysis of scalp EEG recordings. However, demonstration of the validity and clinical utility of these mathematically derived source modeling techniques has struggled to keep pace. This review evaluates the current clinical “fitness’ of ESL as applied to the focal epilepsies by examining some of the key studies performed in the field, with emphasis given to clinical work published in the last five years. In doing so, we discuss why ESL techniques have not made an impact on routine epilepsy practice, underlining some of the current problems and controversies in the field. We conclude by examining where ESL currently sits alongside magnetoencephalography and combined EEG‐functional magnetic resonance imaging in the investigation of focal epilepsy.
Strategies for surgical treatment of epilepsies in developing countries
Authors: Asadi‐Pooya Ali A. , Sperling Michael R. 
Published: October 2007

Summary Epilepsy surgery has been proved to be efficacious, safe and cost‐effective in developing countries. However, the success of epilepsy surgery depends on selecting suitable candidates based on the available resources and technologies. Some of the challenges to provide appropriate surgical treatment for epilepsy patients in developing countries include providing human and technological resources and developing realistic presurgical protocols. Detection of ideal candidates for epilepsy surgery is possible for well‐trained epileptologists with the help of basic investigative technologies, for example, magnetic resonance imaging (MRI) and electroencephalography (EEG). Patients with potentially epileptogenic, well‐circumscribed lesions on MRI and patients with mesial temporal lobe epilepsy (MTLE) are reasonable candidates for surgery. Palliative epilepsy surgeries include corpus callosotomy and other disconnections. These operations are feasible in developing countries with a knowledgeable team consisting of an epileptologist, neurosurgeon and technicians and with using MRI and EEG as basic investigative technologies.
A combination of ketamine and diazepam synergistically controls refractory status epilepticus induced by cholinergic stimulation
Authors: Martin Brandon S. , Kapur Jaideep 
Published: October 2007

Summary
Purpose: New treatments are needed for status epilepticus (SE) that is refractory to drugs modulating GABAA receptors, and NMDA receptor antagonists are candidate drugs.
Methods: Clinically available NMDA receptor antagonist ketamine was tested for effectiveness in terminating prolonged SE induced by a combination of lithium and pilocarpine. Animals were treated 10 min after first grade 5 behavioral seizure (Racine scoring scale) by intraperitoneal administration of ketamine, diazepam, or saline. Seizure termination was determined by electroencephalogram (EEG) recordings from the hippocampus and the cortex.
Results: Animals treated with normal saline or either 20 mg/kg diazepam, or 50 mg/kg ketamine continued in SE for the next 300 min. However, combined treatment with diazepam and ketamine rapidly terminated prolonged cholinergic stimulation‐induced SE. Detailed study of dose response relationships demonstrated that diazepam enhanced efficacy and potency of ketamine in terminating SE.
Discussion: This study demonstrated synergistic action of diazepam and ketamine in terminating SE. It suggests that a ketamine–diazepam combination might be a clinically useful therapeutic option for the treatment of refractory SE.
Glutamate and dopamine receptors contribute to the lateral spread of epileptiform discharges in rat neocortical slices
Authors: Goda Michael , Kovac Stjepana , Speckmann Erwin‐Josef , Gorji Ali 
Published: October 2007

Summary
Purpose: The effects of AMPA‐type glutamate receptor as well as dopamine D1 and D2 receptors on the lateral propagation of epileptiform field potentials (EFP) were studied across adjacent areas of rat neocortical tissues.
Methods: Epileptiform burst discharges were induced by superfusion of Mg2+‐free artificial cerebrospinal fluid. Simultaneous field potential recordings of EFP were obtained from four microelectrodes placed 2–3 mm apart across coronal slices in the third layer of the neocortex. The effects of AMPA receptor antagonist 6‐cyano‐7‐nitroquinoxaline‐2,3‐dione (CNQX), dopamine D1 receptor agonist SKF 81297, and dopamine D2 receptor agonist quinpirole on lateral propagation of burst discharges were investigated.
Results: CNQX, applied focally between recording sites, blocked rapid propagation across treated areas and resulted in the emergence of spatially separate, independent pacemakers. Focal application of SKF 81297 between recording sites increased the repetition rate of EFP, but reduced the amplitude as well as the duration of epileptic discharges. However, addition of SKF 81297 to the bath medium abolished EFP. Both local and systemic applications of quinpirole irreversibly enhanced repetition rate of epileptiform burst discharges.
Conclusions: The results indicate the prerequisite of AMPA synaptic transmission for synchronized lateral propagation of Mg2+‐free ACSF‐induced epileptic activity and the modulatory effects of dopamine D1 and D2 receptors on both EFP initiation and propagation in epileptic tissues.