bluuebunny/crossref_metadata_2025 huggingface dataset:
Acute cutaneous barrier disruption activates epidermal p44/42 and p38 mitogen‐activated protein kinases in human and hairless guinea pig skin
Authors: Kobayashi Hiromi , Aiba Setsuya , Yoshino Yumiko , Tagami Hachiro
Published: December 2004

Abstract:  Acute cutaneous barrier disruption of the skin elicits various homeostatic repair responses in the epidermis. Although several candidates for the signaling mechanisms that induce these responses have been reported, e.g. the calcium and ion concentration, peroxisome proliferator‐activated receptor‐α, and TNF‐α signaling mediated by sphingomyelinases, the exact nature of the signals remains undetermined. Therefore, assuming that an important group of serine/threonine‐signaling kinases, mitogen‐activated protein kinases (MAPKs), such as p44/42 MAPK, p38 MAPK, and SAPK/JNK, might link the barrier disruption to the subsequent homeostatic responses, the activation of three MAPKs in hairless guinea pig or in human skin after barrier disruption was investigated. The epidermal barrier was insulted with tape stripping or organic solvents, and the activation of these MAPKs was examined with immunohistochemistry, Western blotting, and immune complex kinase assay. In the skin of hairless guinea pigs, p44/42 MAPK and p38 MAPK, but not SAPK/JNK, were activated in epidermal keratinocytes immediately after tape stripping, and continued to be activated for at least 180 min. The activation of p44/42 MAPK was well correlated with an increase in transepidermal water loss, which was positively correlated with the number of tape strippings, whereas the covering of the stripped skin with occlusive dressing or with Ca2++ K++sucrose solution suppressed its activation. The activation of p44/42 MAPK was also induced by treatment of the skin with organic solvents. In a similar fashion, p44/42 and p38 MAPKs were found to be activated in human skin after tape stripping. These results strongly suggest that the activation of p44/42 and p38 MAPKs links the stimuli of barrier disruption to the subsequent homeostatic responses to repair the barrier defect.
Routine flow cytometric immuno‐staining of T‐cell perforin is preserved using diethylene glycol for erythrocyte‐lysis but lost by the use of ammonium chloride
Authors: Ambach Andreas , Bonnekoh Bernd , Gollnick Harald
Published: December 2004

Abstract:  The system of perforin‐containing lytic granules of cytotoxic lymphocytes plays an important role in the immune defense machinery. Investigating the capacity and efficacy of this system in and ex vivo is helpful to understand immune responses and their modulation by therapeutic interventions. With regard to its pathophysiological function, we recently demonstrated a substantial increase of perforin‐positive CD8+ T cells in the peripheral blood of patients with acute exacerbated psoriasis and severe generalized drug reactions, and, in marked contrast, a highly significant perforin‐depletion and a perforin‐hyperreleasability in atopic dermatitis (AD). To streamline the perforin staining procedure, isolation of peripheral blood mononuclear cells (PBMC) by Ficoll density centrifugation was to be replaced by lysis of erythrocytes. Ammonium chloride lysis, however, reduced the perforin content of CD8+ T cells substantially (up to 75–100%) as compared with Ficoll isolation of PBMC. Incubation of cells in concanamycin A, a selective inhibitor of H+‐ATPases, resulted in a similar loss of perforin staining pointing to the critical influence of lysosomal pH. Using diethylene glycol‐mediated erythrocyte lysis, perforin was well preserved to be readily detectable by immuno flow cytometry. Representative examples of the application of this optimized perforin staining procedure as well as accumulated data are given for various dermatological disorders [psoriasis, atopic dermatitis, cutaneous drug reactions, graft‐versus‐host disease (GVHD)] with strong involvement of the cytotoxic T‐cell population. Our findings may help to explain recent conflicting reports about a widely varying range of the portion of perforin‐positive cells in healthy individuals as a reflection of such artificial methodological influences.
Cytochrome P4501A1 polymorphisms in a Caucasian population with porphyria cutanea tarda
Authors: Gardlo K. , Selimovic D. , Bolsen K. , Ruzicka T. , Abel J. , Fritsch C.
Published: December 2004

Abstract: Porphyria cutanea tarda (PCT) is the most frequent porphyria in humans. The familial type is in contrast to the sporadic type due to an inherited defect of the uroporphyrinogen‐III‐decarboxylase (URO‐D) and both types need additional porphyrinogens to lead to the clinical manifestation of the disease. Various factors such as xenobiotics (i.e. polycyclic aromatic hydrocarbons), alcohol, hormones and viral liver infections (hepatitis B and C) are known to induce porphyria. Cytochrome P450 enzymes play a crucial role in the metabolism of porphyrogens and therefore might have an important influence on the pathogenesis of hepatic porphyrias. Association of CYP1A2 polymorphisms with susceptibility to both types of PCT has already been described in Danish patients. We investigated 65 Caucasian patients with PCT in comparison to a healthy control group concerning the type of PCT and the cytochrome P4501A1 polymorphisms (m1, m2 and m4) using polymerase chain reaction (PCR) and a restriction fragment length polymorphism. We found an increased incidence of the m4 polymorphism in the familial type of PCT (odds ratio 5.5, P‐value 0.01), whereas the m1 and m2 mutations were not significantly higher than in the healthy control group. These results suggest that familial PCT, in addition to the genetic mutations, might be provoked by a higher susceptibility to porphyrogens via the cytochrome P4501A1 m4 polymorphism.
Distributional, morphological and genetic consequences of dispersal for temporary pond water mites
Authors: Bohonak Andrew J. , Smith Bruce P. , Thornton Melissa
Published: December 2004

1. To determine the consequences of dispersal and gene flow for temporary pond water mites (Hydrachnida), we compared distributional, genetic and morphological characters in the closely related speciesArrenurus angustilimbatusandA. rufopyriformis.The former has larvae that parasitise and disperse on adult mosquitoes, whereas larvae of the latter forego any association with hosts.

2. Allometrically adjusted egg size and gonopore size were found to be useful characters for distinguishing between females of the two species.

3.Arrenurus angustilimbatuspossesses a broader and more continuous geographic distribution than its ‘direct developing’ counterpart. Allozyme heterozygosity was higher and population differentiation lower inA. angustilimbatus. In addition, populations ofA. rufopyriformiswere morphologically divergent, whereas populations ofA. angustilimbatuswere not. Isolation by distance analyses on both genetic and morphological characters indicated that the results were not biased by different sampling regimes for the two species.

4. These results demonstrate the importance of mosquito parasitism for maintaining ecological and genetic linkages betweenA. angustilimbatuspopulations. More broadly, we hypothesise that insect‐mediated dispersal has contributed to the ecological and evolutionary success of water mites, because the Hydrachnida lack other obvious adaptations for dispersing in space or time.
Forward computation of the magnetic field of a 3D body with arbitrary boundary and continually varying magnetization
Authors: An Yulin , Huang Jinming , Chen Yudong
Published: December 2004

The forward computation of the gravitational and magnetic fields due to a 3D body with an arbitrary boundary and continually varying density or magnetization is an important problem in gravitational and magnetic prospecting. In order to solve the inverse problem for the arbitrary components of the gravitational and magnetic anomalies due to an arbitrary 3D body under complex conditions, including an uneven observation surface, the existence of background anomalies and very little or no a priori information, we used a spherical coordinate system to systematically investigate forward methods for such anomalies and developed a series of universal spherical harmonic expansions of gravitational and magnetic fields. For the case of a 3D body with an arbitrary boundary and continually varying magnetization, we have also given the surface integral expressions for the common spherical harmonic coefficients in the expansion of the magnetic field due to the body, and a very precise numerical integral algorithm to calculate them. Thus a simple and effective method of solving the forward problem for magnetic fields due to 3D bodies of this kind has been found, and in this way a foundation is laid for solving the inverse problem of these magnetic fields. In addition, by replacing the parameters and unit vectors in the spherical harmonic expansion of a magnetic field by gravitational parameters and a downward unit vector, we have also derived a forward method for the gravitational field (similar to that for the magnetic case) of a 3D body with an arbitrary boundary and continually varying density.
Effect of CO2 enrichment and elevated temperature on methane emissions from rice, Oryza sativa
Authors: Schrope M. K. , Chanton J. P. , Allen L. H. , Baker J. T.
Published: December 2004

Methane emissions from rice grown within Temperature Gradient Greenhouse Tunnels under doubled CO2 concentrations were 10–45 times less than emissions from control plants grown under ambient CO2. For two cultivars of rice (cvs. Lemont and IR‐72), methane emissions increased with a temperature increase of 2°, from outdoor ambient temperatures to the first cell of the ambient CO2 tunnel (ambient temperature + 2 °C). Within both tunnels and for both cultivars methane emissions decreased with further temperature increases (from 2° to 5 °C above ambient). Carbon dioxide enrichment stimulated both above‐ and below‐ground production. Our original hypothesis was that increased CO2 would stimulate plant productivity and therefore stimulate methane emission, since direct linkages between these parameters have been observed. We hypothesize that CO2 enrichment led to the attenuation of methane production due to increased delivery of oxygen to the rhizosphere because of increased root biomass and porosity. The increased root biomass due to elevated CO2 may have more effectively aerated the soil, suppressing methane production. However, this study may be unique because the low organic content (< 1%) of the sandy soils in which the rice was grown created very little oxygen demand.
Prostasomes as zinc ligands in human seminal plasma
Authors: Vivacqua A. , Siciliano L. , Sabato M. , Palma A. , Carpino A.
Published: December 2004

Prostasomes are small vesicles, containing zinc, secreted by prostate in human seminal plasma and showing a physiological role on sperm properties. In this study, the possible correspondence between prostasomes and a prostatic high molecular weight protein complex, recently indicated as zinc ligand, has been investigated. Isolated prostasomes, examined by scanning electron microscopy, were dialysed to evaluate their zinc binding capacity. Furthermore, seminal plasma Sephadex G‐75 elution was carried out before and after prostasome removal. Prostasome preparations, containing typical vesicles of 50–500 nm, showed a positive correlation between their zinc and protein levels. They were able to take up zinc against gradient. Furthermore, the seminal zinc amount, bound to the high molecular weight proteins, was strongly reduced in the free‐prostasome sample with respect to the total seminal plasma. This study suggested the correspondence between the prostasomes and a high‐sized zinc ligand complex of prostatic origin. Therefore, it demonstrated, for the first time, the zinc binding capacity of prostasomes, a new property which could be related to their biological functions.
Ecological zoogeography of the bats of Paraguay
Authors: López‐González Celia
Published: December 2004

Aim  To relate the composition of bat assemblages in Paraguay to environmental factors (vegetation) and to test the hypothesis that the observed patterns of distribution of Paraguayan mammals is ultimately due to soils and geological features.

Location  Paraguay.

Methods  Museum specimens were used to create a data base of 3762 individuals of forty‐eight species collected in twenty‐six 50 × 50 km sites distributed throughout the country. Proportion of each of sixteen vegetation types per site was estimated from vegetation maps. Vegetation and bat data were related using canonical correspondence analysis (CCA) and Mantel tests. The same analyses were performed with the bat data grouped in terms of trophic strategies.

Results  A significant relationship was found between composition of vegetation and composition of bat assemblages. CCA ordination arranged plant associations and bat assemblages into three distinct groups: Dry Chaco, Floodable Lands and Eastern Paraguay, which correspond to the major characteristics of the Paraguayan vegetation, geology and soils. Frugivorous bats were restricted to Eastern Paraguay and Floodable Lands, whereas most insectivore and omnivore species occur across the entire country. However, the maximum abundance of insectivorous and omnivorous species within each genus indicates that there is at least a partial segregation of species to one of the three regions, and in those cases where the maximum abundance of congeneric species coincide, those species differ considerably in size.

Main conclusions  The Paraguayan bat fauna is a composite of species from various South American biomes, with no endemic species. However, species are not randomly distributed across the country despite the lack of geographical barriers and the high dispersal capabilities of bats. Instead, species presence at any given site is strongly associated with vegetation patterns that are ultimately the result of the geological history of the area. This correlation can be explained partially in terms of habitat suitability and resource availability. Additionally, results suggest that interspecific interactions are also an important component in determining the composition of a given bat assemblage.
Are rare primate taxa specialists or simply less studied?
Authors: Doherty D. A. , Harcourt A. H.
Published: December 2004

Aim  Rare species are reported to be specialized. However, rare taxa are usually less studied than are common taxa. If so, the reported specialization might be just a result of paucity of records. We here test for this sampling artefact in primates, a taxon in which rarity has been explained by specialization.

Location  Tropical Africa, Madagascar, Asia, Americas.

Methods  We define rare and common species as those with geographical range sizes in the lower and upper quartiles, respectively, for primates in each realm. We conducted two independent searches of published literature to determine if there were significantly fewer studies on a common measure of specialization, diet, for rare vs. common species. We then tested for sampling artefact in reported diet breadth by comparing the number of references needed to obtain it for both rare and common species.

Results  We found, in both literature searches, significantly fewer studies on diet for rare primates – a mode of zero references for rare species, and one for common. By contrast, no significant difference existed for number of references needed to attain the full reported diet breadth: a median of one reference for both specialized, rare and generalized, common species.

Main conclusions  Rare species are indeed studied less. Nevertheless, the finding that rare primates are specialists is not necessarily mere sampling artefact.
Patient and clinician collaboration in the design of a national randomized breast cancer trial
Authors: Marsden Jo , Bradburn Jane ,   on behalf of the Consumers’ Advisory Group for Clinical Trials (CAG‐CT),   the Lynda Jackson Macmillan Centre
Published: December 2004

Objective  To show breast cancer patient involvement in the design of a national randomized trial of hormone replacement therapy (HRT) in symptomatic patients will increase accrual.

Setting and participants  Three stakeholder groups [(1) researchers from the Lynda Jackson Macmillan Centre, (2) the Consumers’ Advisory Group for Clinical Trials (CAG‐CT), (3) clinicians responsible for a pilot randomized HRT study in breast cancer patients] developed this collaborative study.

Methods  (1) Nine focus group discussions were conducted to identify issues relevant to breast cancer patients about HRT and a national trial: six involved women from breast cancer support groups nationwide and three patients who had previously participated in the pilot randomized HRT study. (2) Recommendations from the focus groups (analysed by Grounded Theory) were debated by the research stakeholders and focus group representatives at a 1‐day meeting and consensus reached (using a voting system) on mutual priorities for incorporation into the design of a national HRT trial. (3) Representatives from the CAG‐CT and focus groups participated in subsequent national HRT steering committee meetings to ensure that these priorities were accounted for and the resulting trial design summary was circulated to the CAG‐CT and all focus group representatives for comment.

Results  Focus groups demonstrated that the complexity of factors relating to trial participation was not just restricted to the research topic in question. Patient–clinician interaction provided a platform for negotiating potential conflicts over trial design and outcomes. Patient feedback suggested that mutually agreed priorities were accounted for in the trial design.

Interpretation  Clinical research planning should involve all research stakeholders at the outset. Quantifying the impact of patient involvement in terms of trial accrual may be too simple given the complexity of their motivations for participating in trials.
Monotony and the Information Content of Richardson's Ground Squirrel (Spermophilus richardsonii) Repeated calls: Tonic Communication or Signal Certainty?
Authors: Sloan Jennifer L. , Hare James F.
Published: December 2004

The repetition of elements within an alarm signal is commonly thought to ensure that receivers have detected that signal, or to promote residual vigilance in light of the dangerous circumstances prompting the signal's initial production (tonic communication). Beyond alerting others and maintaining that state of alertness, however, repetitive signal elements may be parsed so as to encode information about the nature of potential threats. To determine how call length and variation in intersyllable latency might prove informative in the repetitive alarm vocalizations of Richardson's ground squirrels (Spermophilus richardsonii), we conducted a field‐based playback experiment quantifying antipredator responses to manipulated alarm calls. Free‐living juvenile squirrels were exposed to playbacks of 12 syllable (long) and six syllable (short) calls with a constant (monotonous) or changing (variable) call rate. The length of calls had no significant effect on the behaviour of call recipients during and immediately after call production; however, call recipients showed greater vigilance after the playback of monotonous calls than after variable calls. The absence of a call length effect is not consistent with tonic communication in the strict sense; rather, enhanced responsiveness to monotonous relative to variable calls suggests that multiple syllables, and the emergent patterns of intersyllable latency, communicate information about response urgency or the distance to a predatory threat. Only monotonous calls convey those aspects with any certainty on the part of the signaller and hence are selectively attended to by receivers.
Effects of Passive Social Support in Juvenile Greylag Geese (Anser anser): A Study from Fledging to Adulthood
Authors: Weiß Brigitte M. , Kotrschal Kurt
Published: December 2004

In general, support by social allies may reduce stress, increase an individual's status and facilitate access to resources. In Greylag geese (Anser anser), offspring stay with their parents for an entire year or even longer and thereby enjoy social support in encounters with other flock members. We investigated the influence of spatial distance to one's allies on the outcome of agonistic encounters in a natural flock situation for a total of 12 sibling groups after fledging. In addition, we tested two groups of hand‐raised juvenile geese over a time span of 11/2 yr. Passive (i.e. not interfering) human supporters of different familiarity were placed at a standard distance during food provisionings, which produced a tight flock situation. Success in agonistic interactions increased with decreasing distance to members of their social unit. The hand‐raised juveniles were more successful in agonistic interactions and showed increased feeding rates when accompanied by a familiar human than when alone or with a non‐familiar human. The effect of the presence of familiar humans on success in agonistic encounters significantly decreased with increasing age, while feeding rates remained elevated. The positive effects of social support were particularly evident in females. We conclude that social support has similar effects and functions in the highly social greylag geese as reported for social mammals.
Fruit Colour Preferences of Redwings (Turdus iliacus): Experiments with Hand‐Raised Juveniles and Wild‐Caught Adults
Authors: Honkavaara Johanna , Siitari Heli , Viitala Jussi
Published: December 2004

Certain fruit colours and their contrast with the background coloration are suggested to attract frugivorous birds. To test the attractiveness of different colours, we performed three experiments in laboratory with controlled light conditions. In the first two experiments, we studied the fruit colour preferences of naive juvenile redwings. In the third experiment, we continued to investigate whether the contrast of the fruit colour with the background coloration affects the preference of both naive juveniles and experienced adult redwings. In the first experiment, juvenile birds preferred black, UV‐blue and red berries, to white ones. In pairwise trials, a new set of juveniles still preferred red berries to white ones. When testing the effect of contrasts on their choice, juveniles preferred UV‐blue berries to red ones on a UV‐blue background. However, no preference was found, when the background was either red or green. Adult redwings preferred UV‐blue berries to red ones on all backgrounds. According to these results, juveniles seem to have an innate avoidance of white berries. Furthermore, the foraging decisions of fruit‐eating birds are affected more by fruit colour than its contrast with background coloration, at least when contrasting displays are encountered from relatively short distances. Differences in preferences of adult and juvenile birds also indicate that learning seems to play a role in fruit choices.
Molecular and functional adaptation of the GABAA receptor complex during pregnancy and after delivery in the rat brain
Authors: Follesa Paolo , Floris Stefania , Tuligi Graziella , Mostallino Maria Cristina , Concas Alessandra , Biggio Giovanni
Published: December 2004

The abundance of γ‐aminobutyric acid receptor type A (GABAA receptor) subunit mRNAs and polypeptides as well as muscimol‐stimulated 36Cl– uptake were measured in rat cerebral cortex or hippocampus at various times during pregnancy and after delivery. RNase protection assays revealed that the amount of the γ2L subunit mRNA decreased progressively during pregnancy, in the cerebral cortex and hippocampus, and then returned to control values around the time of delivery. A similar pattern was observed for the α5 subunit mRNA in the cerebral cortex, whereas no significant changes were apparent for α1, α2, α3, α4, β1, β2, β3 and γ2S subunit mRNAs. The amounts of γ2 and α1 proteins in the cerebral cortex were measured by immunoblot analysis; whereas the abundance of γ2 protein decreased during pregnancy, no change was detected in the amount of α1 protein. Evaluation for functional significance of the down‐regulated γ2 and α5 subunit was made by determining the GABAA receptor function assessed by measurement of muscimol‐stimulated 36Cl– uptake in cerebral cortical membrane vesicles. Muscimol‐induced 36Cl– uptake was markedly reduced during of pregnancy compared with rats in oestrus. At this same time, the potentiating effects of diazepam and allopregnanolone on muscimol stimulation of 36Cl– uptake also were reduced. In contrast, the effects of muscimol, allopregnanolone and diazepam were significantly increased, relative to animals in oestrus, after delivery.
The pattern of ocular dominance columns in cat primary visual cortex: intra‐ and interindividual variability of column spacing and its dependence on genetic background
Authors: Kaschube Matthias , Wolf Fred , Puhlmann Mathias , Rathjen Stefan , Schmidt Karl‐Friedrich , Geisel Theo , Löwel Siegrid
Published: December 2004

We present a comprehensive analysis of the intrinsic variability of the periodicity of ocular dominance columns in cat primary visual cortex (area 17) and its relationship to genetic background and visual experience. We characterized the intra‐areal and interindividual variability of column spacing in a large set (n = 49) of ocular dominance patterns adapting a recently developed technique for the two‐dimensional analysis of orientation column patterns. Patterns were obtained from three different cat colonies (termed F, M and D), the cats having either normal visual experience or experimentally induced strabismus. Two‐dimensional maps of local column spacing were calculated for every pattern. In individual cortices, local column spacings varied by > 50% with the majority of column spacings ranging between 0.6 and 1.5 mm in different animals. In animals from colonies F and M (n = 29), the mean column spacing ranged between 1.03 and 1.27 mm and exhibited no significant differences, either between the two breeds or between strabismic and normal animals. The mean spacing was moderately clustered in the left and right brain hemisphere of individual animals but not in littermates. In animals from colony D (n = 2), average column spacing ranged between 0.73 and 0.95 mm, and was thus significantly different from the distribution of spacings in animals from breeds F and M, suggesting an influence of genetic factors on the layout of ocular dominance columns. Local column spacing exhibited a considerable systematic intra‐areal variation, with largest spacings along the representation of the horizontal meridian and smallest spacings along the peripheral representation of the vertical meridian. The total variability of ocular dominance column spacing comprised 24% systematic intra‐areal variation, 18% interindividual differences of mean column spacing and 58% nonsystematic intra‐areal variability.
MRI and in situ hybridization reveal early disturbances in brain size and gene expression in the megencephalic (mceph/mceph) mouse
Authors: Diez Margarita , Schweinhardt Petra , Petersson Susanna , Wang Fu‐Hua , Lavebratt Catharina , Schalling Martin , Hökfelt Tomas , Spenger Christian
Published: December 2004

The mouse model for megencephaly, mceph/mceph, carries a truncating deletion in the Shaker‐related voltage gated potassium channel gene 1. Affected mice display neurological disturbances and motor dysfunctions. Symptoms begin to show at 3–4 weeks of age. The cause of the brain enlargement is not clear. To elucidate early events in the development of the disease we used magnetic resonance imaging (MRI) to quantify, over time, the increase in size of several discrete brain regions in the same mice at 3, 8 and 12 weeks of age. We also analysed markers for neuropeptides and growth factors to explore their possible involvement at an early stage. The results show an enlargement of the total coronal area of the brain already at 3 weeks of age. Total brain volume, ventral cortex, hippocampal formation and cerebral cortex were enlarged at 8 weeks and onwards. Thalamus, brainstem, cerebellum and spinal cord did not differ from controls even at 12 weeks. We also report distinct disturbances in the expression of brain‐derived neurotrophic factor, insulin‐like growth factor binding protein 6 and several neuropeptides at 2 and 3 weeks of age, that is, before an obvious behavioural phenotype can be observed. These results provide an objective description of the size changes in different brain regions of the mceph/mceph mouse, and suggest that certain molecules could be involved in the early processes underlying these changes.
Active release of glycine or d‐serine saturates the glycine site of NMDA receptors at the cerebellar mossy fibre to granule cell synapse
Authors: Billups Daniela , Attwell David
Published: December 2004

The current and calcium influx generated by NMDA receptors depend on the concentration of the coagonist glycine, or its analogue d‐serine, in the synaptic cleft. If there is no release of glycine, the ionic stoichiometry of the glial GlyT1 glycine transporters expressed near NMDA receptors in the brain should be able to lower the extracellular glycine concentration to below the EC50 for coactivation of NMDA receptors. We examined whether changing the glycine or d‐serine concentration in the superfusion solution altered the NMDA receptor mediated component of the synaptic current at the rat cerebellar mossy fibre to granule cell synapse. Adding up to 100 µm glycine or d‐serine had no effect, implying that the glycine site is saturated. Using the competitive glycine site antagonist 7‐chlorokynurenate, and plausible values for the kinetic parameters of NMDA receptors, we estimate that during activation of the mossy fibres the concentration of glycine or d‐serine in the synaptic cleft is at least 4.6 µm or 1.5 µm, respectively, requiring active release of glycine or d‐serine.
LRRN6A/LERN1 (leucine‐rich repeat neuronal protein 1), a novel gene with enriched expression in limbic system and neocortex
Authors: Carim‐Todd Laura , Escarceller Mònica , Estivill Xavier , Sumoy Lauro
Published: December 2004

Human chromosome 15q24‐q26 is a very complex genomic region containing several blocks of segmental duplications to which susceptibility to anxiety disorders has been mapped (Gratacos et al., 2001, Cell, 106, 367–379; Pujana et al., 2001, Genome Res., 11, 98–111). Through an in silico gene content analysis of the 15q24‐q26 region we have identifie1d a novel gene, LRRN6A (leucine‐rich repeat neuronal 6A), and confirmed its location to the centromeric end of this complex region. LRRN6A encodes a transmembrane leucine‐rich repeat protein, LERN1 (leucine‐rich repeat neuronal protein 1), with similarity to proteins involved in axonal guidance and migration, nervous system development and regeneration processes. The identification of homologous genes to LRRN6A on chromosomes 9 and 19 and the orthologous genes in the mouse genome and other organisms suggests that LERN proteins constitute a novel subfamily of LRR (leucine‐rich repeat)‐containing proteins. The LRRN6A expression pattern is specific to the central nervous system, highly and broadly expressed during early stages of development and gradually restricted to forebrain structures as development proceeds. Expression level in adulthood is lower in general but remains stable and significantly enriched in the limbic system and cerebral cortex. Taken together, the confirmation of LRRN6A's expression profile, its predicted protein structure and its similarity to nervous system‐expressed LRR proteins with essential roles in nervous system development and maintenance suggest that LRRN6A is a novel gene of relevance in the molecular and cellular neurobiology of vertebrates.
The physiological and morphological characteristics of interneurons caudal to the trigeminal motor nucleus in rats
Authors: Min Ming‐Yuan , Hsu Pei‐Chien , Yang Hsiu‐Wen
Published: December 2004

In this study we have characterized the membrane properties and morphology of interneurons which lie between the caudal pole of the trigeminal motor nucleus and the rostral border of the facial motor nucleus. Previous studies suggest that many of these interneurons may participate in the genesis of rhythmical jaw movements. Saggital brainstem slices were taken from rats aged 5–8 days. Interneurons lying caudal to the trigeminal motor nucleus were visualized using near‐infrared differential interference contrast (DIC) microscopy, and were recorded from using patch pipettes filled with a K‐gluconate‐ and biocytin‐based solution. The 127 neurons recorded could be categorized into three subtypes on the basis of their responses to injection of depolarizing current pulses, namely tonic firing (type I), burst firing (type II) and spike‐adaptive (type III) neurons. Type I interneurons had a higher input resistance and a lower rheobase than type II neurons. All three neuron subtypes showed ‘sag’ of the voltage response to injection of large‐amplitude hyperpolarizing current pulses, and, in addition, also showed rectification of the voltage response to injection of depolarizing current pulses, with type II neurons showing significantly greater rectification than type I neurons. The axonal arborizations were reconstructed for 44 of 63 neurons labelled with tracer. Neurons of each subtype were found to issue axon collaterals terminating in the brainstem nuclei, including the parvocellular reticular nucleus (PCRt), the trigeminal motor nucleus (Vmot), the supratrigeminal nucleus or the trigeminal mesencephalic nucleus. Twenty‐five of the 43 neurons issued collaterals which terminated in the Vmot and the other brainstem nuclei. When viewed under 100× magnification, the collaterals of some interneurons were seen to give off varicosities and end‐terminations which passed close to the somata of unidentified neurons in the trigeminal motor nucleus and in the area close to the interneuron soma itself. This suggests that the interneurons may make synaptic contacts both on motoneurons and also on nearby interneurons. These results provide data on the membrane properties of trigeminal interneurons and evidence for their synaptic connections both with nearby interneurons and also with motoneurons. Thus, the interneurons examined could play roles in the shaping, and possibly also in the generation, of rhythmical signals to trigeminal motoneurons.
Contribution of spinal inhibitory receptors in heterosegmental antinociception induced by noxious stimulation
Authors: Tambeli C. H. , Quang P. , Levine J. D. , Gear R. W.
Published: December 2004

Noxious (i.e. painful) stimulation in the rat induces profound heterosegmental antinociception as demonstrated by the ability of either thermal stimulation (50 °C water) or subdermal capsaicin injection in the hindpaw to attenuate the nociceptive trigeminal jaw‐opening reflex. Importantly, noxious stimulus‐induced antinociception (NSIA) is mediated by endogenous opioids (as well as other neurotransmitters) in nucleus accumbens, as indicated by the ability of intra‐accumbens administration of mu‐ or delta‐opioid receptor antagonists to block NSIA. Although noxious peripheral stimulation is known to release excitatory neurotransmitters such as glutamate at the level of the spinal cord, the present study was designed to test the hypothesis that NSIA depends on further activation of spinal inhibitory receptors. This hypothesis was based on findings that inhibition of spinal processing (e.g. intrathecal local anaesthetic administration) also produces heterosegmental antinociception mediated by endogenous opioids in nucleus accumbens. Thus, to reconcile the paradoxical findings that both spinal excitation and inhibition appear to activate the same nucleus accumbens opioid‐mediated antinociceptive mechanism, we investigated whether spinal administration of antagonists for inhibitory receptors would block the antinociceptive effect of subdermal capsaicin. We report that spinal administration of selective antagonists for mu‐opioid (Cys2, Tyr3, Orn5, Pen7amide), kappa‐opioid (nor‐binaltorphimine), GABA‐A (bicuculline), GABA‐B (CGP 35348) and glycine (strychnine) receptors significantly reduced NSIA. The selective delta‐opioid receptor antagonist naltrindole had no significant effect. These results, together with our previous findings, suggest that peripheral noxious stimuli release endogenous opioids, GABA and glycine in the spinal cord which, in turn, inhibit tonic pronociceptive spinal activity to produce heterosegmental antinociception mediated in nucleus accumbens.
A reporter allele for investigating connexin 26 gene expression in the mouse brain
Authors: Filippov Mikhail A. , Hormuzdi Sheriar G. , Fuchs Elke C. , Monyer Hannah
Published: December 2004

A variety of connexins are expressed in the diverse cell types of the central nervous system and are thought to regulate some of the functional properties exhibited by immature and mature cells. A proper understanding of the role of specific connexins in these processes requires an unambiguous characterization of their spatial and temporal pattern of expression. In order to define the cellular distribution of connexin 26 (Cx26) in the mouse we have generated a reporter allele (Cx26lacZ) by genetically manipulating the locus so that the β‐galactosidase (lacZ) gene is expressed from the endogenous Cx26 promoter. This modification decreased expression from the allele and resulted in embryonic lethality for the Cx26lacZ/lacZ genotype in accordance with previous studies on Cx26 knock‐out animals indicating that Cx26‐containing gap junctions are necessary for embryonic development. Despite the lower than expected transcript levels, the amount of lacZ protein produced in heterozygous mice was sufficient to label tissues known to contain Cx26, such as liver, kidney, skin, cochlea, small intestine, placenta and thyroid gland. In the embryonic and mature central nervous system, however, lacZ was restricted to meningeal cells and could not be detected in either neurons or glia. The absence of Cx26 mRNA in these cells could also be confirmed by reverse transcription–polymerase chain reaction and in situ hybridization. Our experiments indicate that the Cx26lacZ mouse line can be used as a reporter of Cx26 gene expression and suggest that Cx26, contrary to previous reports, is restricted to the meninges in both embryonic and adult brain.
Ca2+‐independent muscarinic excitation of rat medial entorhinal cortex layer V neurons
Authors: Egorov Alexei V. , Angelova Plamena R. , Heinemann Uwe , Müller Wolfgang
Published: December 2004

Cholinergic activation of entorhinal cortex (EC) layer V neurons plays a crucial role in the medial temporal lobe memory system and in the pathophysiology of temporal lobe epilepsy. Here, we demonstrate that muscarinic activation by focal application of carbachol depolarizes EC layer V neurons and induces epileptiform activity in rat brain slices. These seizure‐like bursts are associated with a somatic [Ca2+]i increase of 293 ± 82 nm and are blocked by the glutamate receptor antagonists CNQX and APV. Muscarinic activation did not directly evoke a [Ca2+]i increase, but subthreshold and suprathreshold depolarization did. Functional axon mapping revealed local axon branching as well as axon collaterals ascending to layers II and III. During blockade of ionotropic glutamatergic AMPA and NMDA receptors, carbachol depolarized layer V neurons by +7.5 ± 3.4 mV. This direct muscarinic depolarization was associated with a conductance increase of 35 ± 10.3% (+4.3 ± 1.25 nS). Intracellular buffering of [Ca2+]i changes did not block this depolarization, but prolonged action potential duration and reduced adaptation of action potential firing. The muscarinic depolarization was neither blocked by combining intracellular Ca2+‐buffering (EGTA or BAPTA) with non‐specific Ca2+‐channel inhibition by Ni+ (1 mm), nor by Ba2+ (1 mm) nor during inhibition of the h‐current by 2 mm Cs+. In whole‐cell patch‐clamp recording, reversal of the muscarinic current occurred at about −45 mV and −5 mV with complete substitution of intrapipette K+ with Cs+. Thus, muscarinic depolarization of EC layer V neurons appears to be primarily mediated by Ca2+‐independent activation of non‐specific cation channels that conduct K+ about three times as well as Na+.
5‐HT inhibits N‐type but not L‐type Ca2+ channels via 5‐HT1A receptors in lamprey spinal neurons
Authors: Hill Russell H. , Svensson Erik , Dewael Yannick , Grillner Sten
Published: December 2004

5‐HT is a potent modulator of locomotor activity in vertebrates. In the lamprey, 5‐HT dramatically slows fictive swimming. At the neuronal level it reduces the postspike slow afterhyperpolarization (sAHP), which is due to apamin‐sensitive Ca2+‐dependent K+ channels (KCa). Indirect evidence in early experiments suggested that the sAHP reduction results from a direct action of 5‐HT on KCa channels rather than an effect on the Ca2+ entry during the action potential [Wallén et al., (1989) J. Neurophysiol., 61, 759–768]. In view of the characterization of different subtypes of Ca2+ channels with very different properties, we now reinvestigate if there is a selective action of 5‐HT on a Ca2+ channel subtype in dissociated spinal neurons in culture. 5‐HT reduced Ca2+ currents from high voltage activated channels. N‐type, but not L‐type, Ca2+ channel blockers abolished this 5‐HT‐induced reduction. It was also confirmed that 5‐HT depresses Ca2+ currents in neurons, including motoneurons, in the intact spinal cord. 8‐OH‐DPAT, a 5‐HT1A receptor agonist, also inhibited Ca2+ currents in dissociated neurons. After incubation in pertussis toxin, to block Gi/o proteins, 5‐HT did not reduce Ca2+ currents, further indicating that the effect is caused by an activation of 5‐HT1A receptors. As N‐type, but not L‐type, Ca2+ channels are known to mediate the activation of KCa channels and presynaptic transmitter release at lamprey synapses, the effects of 5‐HT reported here can contribute to a reduction in both actions.
Numb rats walk – a behavioural and fMRI comparison of mild and moderate spinal cord injury
Authors: Hofstetter Christoph P. , Schweinhardt Petra , Klason Tomas , Olson Lars , Spenger Christian
Published: December 2004

Assessment of sensory function serves as a sensitive measure for predicting the functional outcome following spinal cord injury in patients. However, little is known about loss and recovery of sensory function in rodent spinal cord injury models as most tests of sensory functions rely on behaviour and thus motor function. We used functional magnetic resonance imaging (fMRI) to investigate cortical and thalamic BOLD‐signal changes in response to limb stimulation following mild or moderate thoracic spinal cord weight drop injury in Sprague–Dawley rats. While there was recovery of close to normal hindlimb motor function as determined by open field locomotor testing following both degrees of injury, recovery of hindlimb sensory function as determined by fMRI and hotplate testing was only seen following mild injury and not following moderate injury. Thus, moderate injury can lead to near normal hindlimb motor function in animals with major sensory deficits. Recovered fMRI signals following mild injury had a partly altered cortical distribution engaging also ipsilateral somatosensory cortex and the cingulate gyrus. Importantly, thoracic spinal cord injury also affected sensory representation of the upper nonaffected limbs. Thus, cortical and thalamic activation in response to forelimb stimulation was significantly increased 16 weeks after spinal cord injury compared to control animals. We conclude that both forelimb and hindlimb cortical sensory representation is altered following thoracic spinal cord injury. Furthermore tests of sensory function that are independent of motor behaviour are needed in rodent spinal cord injury research.
Internalization at glutamatergic synapses during development
Authors: Petralia Ronald S. , Wang Ya‐Xian , Wenthold Robert J.
Published: December 2004

Glutamate receptors are internalized from the cell membrane via clathrin‐coated pits. However, little is known about where this occurs − whether at or near the synapse or at some distance from it. In this study we used immunogold localization in the rat brain (mainly hippocampus) to show that clathrin‐coated pits are found both at the edge of the synaptic active zone and at further postsynaptic distances, including on the sides of the spine; we also localize these pits specifically to glutamatergic synapses. In addition, we show that clathrin‐coated pits can internalize both N‐methyl‐d‐aspartate (in vivo) and α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionate (in vitro data only) receptors at extrasynaptic sites not associated directly with synapses. Also, caveolin might be prevalent at excitatory synapses, although it is not known whether it is involved in receptor internalization, receptor stabilization, or some other function.
Herpes simplex virus type 1 inoculation enhances hippocampal excitability and seizure susceptibility in mice
Authors: Wu Hung‐Ming , Huang Chiung‐Chun , Chen Shun‐Hua , Liang Ying‐Ching , Tsai Jing‐Jane , Hsieh Ching‐Liang , Hsu Kuei‐Sen
Published: December 2004

Herpes simplex virus type 1 (HSV‐1) is the major pathogen related to epilepsy. However, little is known about the pathogenesis of HSV‐1‐associated epilepsy. Here, we report that corneal inoculation of mice with HSV‐1 induces acute spontaneous behavioural and electrophysiological seizures and chronically increases hippocampal excitability and seizure susceptibility. In slices from infected mice, the surviving hippocampal CA3 pyramidal neurons exhibited a more depolarizing resting membrane potential concomitant with an increase in membrane input resistance. They also had a lower threshold for generating synchronized bursts and a decrease in the amplitude of afterhyperpolarization (AHP) than did controls. These results suggest that a direct change in the excitability of the hippocampal CA3 neuronal network could play an important role in facilitating the development of acute seizures and subsequent epilepsy.
Control of eye orientation: where does the brain's role end and the muscle's begin?
Authors: Angelaki Dora E. , Hess Bernhard J. M.
Published: December 2004

Our understanding of how the brain controls eye movements has benefited enormously from the comparison of neuronal activity with eye movements and the quantification of these relationships with mathematical models. Although these early studies focused on horizontal and vertical eye movements, recent behavioural and modelling studies have illustrated the importance, but also the complexity, of extending previous conclusions to the problems of controlling eye and head orientation in three dimensions (3‐D). An important facet in understanding 3‐D eye orientation and movement has been the discovery of mobile, soft‐tissue sheaths or ‘pulleys’ in the orbit which might influence the pulling direction of extraocular muscles. Appropriately placed pulleys could generate the eye‐position‐dependent tilt of the ocular rotation axes which are characteristic for eye movements which follow Listing's law. Based on such pulley models of the oculomotor plant it has recently been proposed that a simple two‐dimensional (2‐D) neural controller would be sufficient to generate correct 3‐D eye orientation and movement. In contrast to this apparent simplification in oculomotor control, multiple behavioural observations suggest that the visuo‐motor transformations, as well as the premotor circuitry for saccades, pursuit eye movements and the vestibulo‐ocular reflexes, must include a neural controller which operates in 3‐D, even when considering an eye plant with pulleys. This review summarizes the most recent work and ideas on this controversy. In addition, by proposing directly testable hypotheses, we point out that, in analogy to the previously successful steps towards elucidating the neural control of horizontal eye movements, we need a quantitative characterization first of motoneuron and next of premotor neuron properties in 3‐D before we can succeed in gaining further insight into the neural control of 3‐D motor behaviours.