bluuebunny/crossref_metadata_2025_split huggingface dataset:
Extra-nuclear effects on growth and development in the sand cricket Gryllus firmus
Authors: Roff D. A. , Sokolovska N. 
Published: December 2004

Abstract
Although largely ignored until recently, parental effects on the phenotypes of their offspring are both ubiquitous in nature and of a potentially great importance to evolution. Our study examines the presence of extra-nuclear (maternal and paternal) effects in growth traits, development time and adult size in the sand cricket Gryllus firmus using a diallel cross of inbred lines. Sex linkage was shown to be nonsignificant for development time but the other traits could not be tested. We assume that they are nonsignificant but use the term ‘reciprocal’ effects to include this effect. We show that reciprocal effects are present in the growth traits and development time, where they account for 10–30% of the phenotypic variance. They are not present in adult size as indexed by head width. We demonstrate that reciprocal effects are due, at least in part, to maternal effects by an analysis of the positive correlation between egg size, a maternal trait, and the growth traits. The growth rate traits show no significant decline with age either with respect to extra-nuclear contributions to variance or difference between phenotypic means of reciprocal pairs. This study demonstrates that extra-nuclear effects are important contributors to the phenotypic variation in life history traits of G. firmus.
‘Antifreeze’ glycoproteins from polar fish
Authors: Harding Margaret M. , Anderberg Pia I. , Haymet A. D. J. 
Published: December 2004

Antifreeze glycoproteins (AFGPs) constitute the major fraction of protein in the blood serum of Antarctic notothenioids and Arctic cod. Each AFGP consists of a varying number of repeating units of (Ala‐Ala‐Thr)n, with minor sequence variations, and the disaccharide β‐d‐galactosyl‐(1→3)‐α‐N‐acetyl‐d‐galactosamine joined as a glycoside to the hydroxyl oxygen of the Thr residues. These compounds allow the fish to survive in subzero ice‐laden polar oceans by kinetically depressing the temperature at which ice grows in a noncolligative manner. In contrast to the more widely studied antifreeze proteins, little is known about the mechanism of ice growth inhibition by AFGPs, and there is no definitive model that explains their properties. This review summarizes the structural and physical properties of AFGPs and advances in the last decade that now provide opportunities for further research in this field.High field NMR spectroscopy and molecular dynamics studies have shown that AFGPs are largely unstructured in aqueous solution. While standard carbohydrate degradation studies confirm the requirement of some of the sugar hydroxyls for antifreeze activity, the importance of following structural elements has not been established: (a) the number of hydroxyls required, (b) the stereochemistry of the sugar hydroxyls (i.e. the requirement of galactose as the sugar), (c) the acetamido group on the first galactose sugar, (d) the stereochemistry of the β‐glycosidic linkage between the two sugars and the α‐glycosidic linkage to Thr, (e) the requirement of a disaccharide for activity, and (f) the Ala and Thr residues in the polypeptide backbone. The recent successful synthesis of small AFGPs using solution methods and solid‐phase chemistry provides the opportunity to perform key structure‐activity studies that would clarify the important residues and functional groups required for activity.Genetic studies have shown that the AFGPs present in the two geographically and phylogenetically distinct Antarctic notothenioids and Arctic cod have evolved independently, in a rare example of convergent molecular evolution. The AFGPs exhibit concentration dependent thermal hysteresis with maximum hysteresis (1.2 °C at 40 mg·mL−1) observed with the higher molecular mass glycoproteins. The ability to modify the rate and shape of crystal growth and protect cellular membranes during lipid‐phase transitions have resulted in identification of a number of potential applications of AFGPs as food additives, and in the cryopreservation and hypothermal storage of cells and tissues.
The Chorus Song of Cooperatively Breeding Laughing Kookaburras (Coraciiformes, Halcyonidae: Dacelo novaeguineae): Characterization and Comparison Among Groups
Authors: Baker Myron C. 
Published: December 2004

AbstractI studied vocalizations of laughing kookaburras in Western Australia by sampling the laugh‐song choruses of eight different groups and the isolated vocalizations of four individuals of this cooperatively breeding species. These data provided a description of the acoustic structure of vocal elements of the laugh song and a between‐group comparison of laugh choruses. I identified six different categories of syllables: some syllable types appear graded with modal forms predominating. Group choruses were produced by several birds vocalizing simultaneously, usually following initiation by a single bird producing one of two typical introductory sets of syllable repetitions. Statistical analyses of samples of mid‐chorus vocalizations of kookaburra groups revealed that the samples from each of the eight groups clustered in principal coordinate space and the group clusters segregated from each other to a significant degree. Linear discriminant analysis assigned 24 of the 25 samples to their correct groups. These results suggest that there is group‐specific vocal signature information in the laugh chorus. The within‐group similarity and between‐group differences may result from heritable variation or from imitation learning. Observations of the contexts of the laugh chorus vocalization supported the interpretations of others that the chorus song is involved in group advertisement of territory occupancy and in defense of the communal borders.
The Costs of Neighbors for a Territorial Dragonfly, Perithemis tenera
Authors: Eason Perri K. , Switzer Paul V. 
Published: December 2004

AbstractPast researchers have often considered neighbors to be beneficial to territorial residents, particularly compared with non‐neighbor conspecific competitors. However, neighbors have the potential to be costly to residents in terms of both defensive costs and lost resources. In this study, we assessed the relative costs of defending a mating territory against neighbors and non‐neighbors for the dragonfly Perithemis tenera, comparing across males with different numbers of contiguous neighbors; we also examined the possibility that the presence of contiguous neighbors might reduce the detection of potential mates. When neighbors were present, residents experienced a greater total number of intrusions by males; this increase in intrusions was due to higher numbers of intrusions by neighbors, as the number of intrusions by non‐neighbor males did not differ. Residents with immediately adjacent neighbors also made more sorties toward neighbors than did residents whose nearest neighbors’ territories were not immediately adjacent. Interestingly, although the number of visits by females did not vary with the presence of neighbors, residents with neighbors made fewer sorties toward females than did residents without neighbors. Our results suggest that defensive costs increased when neighbors were present, that residents with neighbors may have missed opportunities to acquire mates, and thus that living with neighbors can be costly in this species.
The usefulness of a modified adult protocol for the clearance of paediatric cervical spine injury in the emergency department
Authors: Browne Gary J , Lam Lawrence T , Barker Ruth A 
Published: December 2004

AbstractObjective: To determine if the use of a modified adult protocol that uses cervical spine imaging on presentation for the assessment of cervical spine injury in children improves clinical outcome.Methods: This is a case series study on all consecutive trauma patients presenting from April to July 2000 inclusive to the ED of a major paediatric trauma hospital. Children presenting to the ED with potential cervical spine injury (CSI) were identified using standard selection criteria. Patient demographics, mechanism of injury, method and time of presentation, associated injuries, radiological investigation and clinical outcome were recorded. The major outcome measures for this study were: time to clearance of the cervical spine, length of stay in the ED and admission to an in‐hospital bed. Data were analysed for compliance to the protocol, this being the standard assessment pathway of cervical spine clearance used by our trauma service.Results: The trauma registry identified 1721 trauma presentations during the 4‐month study period; 208 presentations representing 200 children with potential CSI were entered into the study. Males represented 72.5% of the study population, having a mean age of 8.32 years, although 29% were less than 5 years of age. The majority of presentations (69%) occurred outside of normal working hours. In 17.8% of cases the cervical spine was cleared based on clinical assessment alone, half less than 5 years of age. Compliance to the protocol occurred in 78% of presentations. However, when examined by age group, children 5 years of age or above were 1.5 times more likely to comply with the protocol as compared with younger children. Adequate plain imaging was not obtained in 18% of presentations, this group almost exclusively less than 5 years of age. There were no missed injuries and no short or long‐term neurological sequelae reported during this study. There were no differences in time to clearance, length of stay and admission rate between compliant and non‐compliant groups.Conclusions: Modified adult protocols for cervical spine clearance offer guidance in managing the majority of children suffering blunt trauma. However, we recommend caution in rigidly applying such protocols, especially to children of young age.
Atypical presentation of intramedullary spinal cord lesion
Authors: H Kwik Michele , Barakate Michael S , Wong Shen , Tan Lisa 
Published: December 2004

AbstractWe report a patient who presented with atypical clinical manifestations including worsening abdominal pain from an intramedullary spinal cord lesion. It is important to consider non‐abdominal causes of abdominal pain for patients with an atypical presentation. The described case demonstrates the challenges facing the physician with the early diagnosis of acute abdominal pain. Spinal cord lesions, although uncommon, remain a potentially disabling and life‐threatening cause of abdominal pain.
BDNF mRNA expression in rat hippocampus and prefrontal cortex: effects of neonatal ventral hippocampal damage and antipsychotic drugs
Authors: Lipska Barbara K. , Khaing Zin Z. , Weickert Cynthia Shannon , Weinberger Daniel R. 
Published: December 2004

AbstractBrain‐derived neurotrophic factor (BDNF) plays an important role in development, synapse remodelling and responses to stress and injury. Its abnormal expression has been implicated in schizophrenia, a neuropsychiatric disorder in which abnormal neural development of the hippocampus and prefrontal cortex has been postulated. To clarify the effects of antipsychotic drugs used in the therapy of schizophrenia on BDNF mRNA, we studied its expression in rats treated with clozapine and haloperidol and in rats with neonatal lesions of the ventral hippocampus, used as an animal model of schizophrenia. Both antipsychotic drugs reduced BDNF expression in the hippocampus of control rats, but did not significantly lower its expression in the prefrontal cortex. The neonatal hippocampal lesion itself suppressed BDNF mRNA expression in the dentate gyrus and tended to reduce its expression in the prefrontal cortex. These results indicate that, unlike antidepressants, antipsychotics down‐regulate BDNF mRNA, and suggest that their therapeutic properties are not mediated by stimulation of this neurotrophin. To the extent that the lesioned rat models some pathophysiological aspects of schizophrenia, our data suggest that a neurodevelopmental insult might suppress expression of the neurotrophin in certain brain regions.
α2A and α2C‐adrenoceptor regulation in the brain: α2A changes persist after chronic stress
Authors: Flügge G. , Van Kampen M. , Meyer H. , Fuchs E. 
Published: December 2004

AbstractStress‐induced activation of the central nervous noradrenergic system has been suspected to induce depressive disorders. As episodes of depression often occur some time after a stress experience we investigated whether stress‐induced changes in the α2‐adrenoceptor (α2‐AR) system persist throughout a post‐stress recovery period. Brains of male tree shrews were analysed after 44 days of chronic psychosocial stress and after a subsequent 10‐day recovery period. Expression of RNA for α2A and α2C‐adrenoceptors was quantified by in situ hybridization, and receptor binding was determined by in vitro receptor autoradiography. Activities of the sympathetic nervous system and of the hypothalamo–pituitary–adrenal axis were increased during chronic stress but normalized during recovery. α2A‐AR RNA in the glutamatergic neurons of the lateral reticular nucleus was elevated significantly after stress and after recovery (by 29% and 17%). In the dorsal motor nucleus of the vagus, subtype A expression was enhanced after recovery (by 33%). In the locus coeruleus, subtype A autoreceptor expression was not changed significantly. Subtype C expression in the caudate nucleus and putamen was elevated by stress (by 5 and 4%, respectively) but normalized during recovery. Quantification of 3H‐RX821002 binding revealed receptor upregulation during stress and/or recovery. Our data therefore show: (i) that chronic psychosocial stress differentially regulates expression of α2‐adrenoceptor subtypes A and C; (ii) that subtype A heteroreceptor expression is persistently upregulated whereas (iii), subtype C upregulation is only transient. The present findings coincide with post mortem studies in depressed patients revealing upregulation of α2A‐ARs.
Delayed peripheral nerve regeneration and central nervous system collateral sprouting in leucocyte common antigen‐related protein tyrosine phosphatase‐deficient mice
Authors: Van der Zee C. E. E. M. , Man T. Y. , Van Lieshout E. M. M. , Van der Heijden I. , Van Bree M. , Hendriks W. J. A. J. 
Published: December 2004

AbstractCell adhesion molecule‐like receptor‐type protein tyrosine phosphatases have been shown to be important for neurite outgrowth and neural development in several animal models. We have previously reported that in leucocyte common antigen‐related (LAR) phosphatase deficient (LAR‐ΔP) mice the number and size of basal forebrain cholinergic neurons, and their innervation of the hippocampal area, is reduced. In this study we compared the sprouting response of LAR‐deficient and wildtype neurons in a peripheral and a central nervous system lesion model. Following sciatic nerve crush lesion, LAR‐ΔP mice showed a delayed recovery of sensory, but not of motor, nerve function. In line with this, neurofilament‐200 immunostaining revealed a significant reduction in the number of newly outgrowing nerve sprouts in LAR‐ΔP animals. Morphometric analysis indicated decreased axonal areas in regenerating LAR‐ΔP nerves when compared to wildtypes. Nonlesioned nerves in wildtype and LAR‐ΔP mice did not differ regarding myelin and axon areas. Entorhinal cortex lesion resulted in collateral sprouting of septohippocampal cholinergic fibres into the dentate gyrus outer molecular layer in both genotype groups. However, LAR‐ΔP mice demonstrated less increase in acetylcholinesterase density and fibre number at several time points following the lesion, indicating a delayed collateral sprouting response. Interestingly, a lesion‐induced reduction in number of (septo‐entorhinal) basal forebrain choline acetyltransferase‐positive neurons occurred in both groups, whereas in LAR‐ΔP mice the average cell body size was reduced as well. Thus, regenerative and collateral sprouting is significantly delayed in LAR‐deficient mice, reflecting an important facilitative role for LAR in peripheral and central nervous system axonal outgrowth.
Kinetic properties of human AMPA‐type glutamate receptors expressed in HEK293 cells
Authors: Grosskreutz Julian , Zoerner Antje , Schlesinger Friedrich , Krampfl Klaus , Dengler Reinhard , Bufler Johannes 
Published: December 2004

AbstractAMPA‐type glutamate receptors (AMPAR) display a high variability in functional properties, which determine the time course of excitatory postsynaptic potentials. They are assembled as tetramers of GluR subunits 1–4 of different splice variants and nuclear edited isoforms. Presently, the kinetics of activation, desensitization and recovery from desensitization of human AMPARs (GluR1, 3 and 4 flip and flop, and GluR2 flip and flop in R and G edited forms, respectively) transiently expressed in HEK293 cells were studied with patch‐clamp techniques and ultra fast agonist application. Activation time constants were identical for all receptors (0.13 ms). The GluR2 flip G variant showed the slowest desensitization (10.8 ms), GluR4 flip the fastest (1.6 ms). Recovery from desensitization varied between 3.1 ms (GluR4 flip) and 178 ms (GluR1 flip). To determine functional interactions between subunits in heteromeric receptors the GluR1 flip and the GluR2 flip R were coexpressed. The time constant of desensitization increased linearly from 2.5 ms (GluR1 flip homomers) to 6.8 ms (GluR2 flip R homomers) with the amount of GluR2 flip R cDNA transfected. Recovery followed a monoexponential time course and had a time constant of 178 ms in GluR1 flip homomeric expression. In all GluR1 flip/GluR2 flip heteromers and in GluR2 flip R homomers desensitization recovered with a time constant of ≈50 ms. Thus, subunit interaction seems likely during recovery but not desensitization. Both parameters might influence the ability of AMPA receptors to mediate glutamate induced chronic excitotoxicity in neurodegenerative diseases.
Migration and differentiation of neural progenitor cells from two different regions of embryonic central nervous system after transplantation into the intact spinal cord
Authors: Enomoto Mitsuhiro , Shinomiya Kenichi , Okabe Shigeo 
Published: December 2004

AbstractTransplantation of in vitro‐expanded neural stem cells (NSCs) is a potentially powerful tool to repair functions of the injured spinal cord. A prerequisite for the successful transplantation therapy is identification of optimized experimental parameters that can promote maximal survival, extensive migration and selective differentiation of the transplanted NSC population in the spinal cord. To this end, we evaluated the basic characteristics of NSC‐like cells from two different donor sources, the embryonic hippocampus and spinal cord, after transplantation into the neonatal spinal cord. Proliferation and differentiation phenotypes of both NSC‐like cells can be controlled by the concentration of fibroblast growth factor‐2 (FGF‐2) in vitro. Both NSC‐like cells can survive within the environment of the intact neonatal spinal cord and showed extensive migratory behaviour shortly after transplantation. However, quantitative analysis revealed preferential migration of hippocampus‐derived cells in the dorsal white matter. Both NSC‐like cells showed restricted phenotype toward the oligodendroglial lineage after transplantation. Transplantation of the mixture of two cell types revealed selective survival of hippocampus‐derived NSC‐like cells. This study indicates the possibility of transplanting hippocampus‐derived NSCs to supply the cell source for immature oligodendrocytes, which are thought to be essential for both the myelination and trophic support of regenerating axons in the dorsal white matter of the spinal cord.
Extra‐cellular dopamine increases in the paraventricular nucleus of male rats during sexual activity
Authors: Melis Maria Rosaria , Succu Salvatora , Mascia Maria Stefania , Cortis Luca , Argiolas Antonio 
Published: December 2004

AbstractDopamine and 3,4‐dihydroxyphenylacetic acid (DOPAC) concentrations were measured in the dialysate obtained with vertical microdialysis probes implanted into the paraventricular nucleus of the hypothalamus of sexually potent male rats. Animals showed noncontact erections when put in the presence of, and copulated with a receptive (ovarietomized oestrogen and progesterone primed) female rat. Dopamine and DOPAC concentrations in the paraventricular dialysate increased 140% and 19%, respectively, above baseline values during exposure to the receptive female and 280% and 31%, respectively, during copulation. No changes in dopamine and DOPAC concentrations were detected in the paraventricular dialysate when sexually potent male rats were exposed to nonreceptive (ovariectomized not oestrogen plus progesterone primed) female rats. These results confirm the involvement of the paraventricular nucleus in control of erectile function and copulatory behaviour and show for the first time that dopamine neurotransmission is increased in this hypothalamic nucleus when erection occurs in physiological contexts.
Perinatal maturation of the mouse respiratory rhythm‐generator: in vivo and in vitro studies
Authors: Viemari Jean‐Charles , Burnet Henri , Bévengut Michelle , Hilaire Gérard 
Published: December 2004

AbstractIn vivo (plethysmography) and in vitro (en bloc preparations) experiments were performed from embryonic day 16 (E16) to postnatal day 9 (P9) in order to analyse the perinatal maturation of the respiratory rhythm‐generator in mice. At E16, delivered foetuses did not ventilate and survive but at E18 they breathed at about 110 cycles/min with respiratory cycles of variable individual duration. From E18 to P0–P2, the respiratory cycles stabilised without changes in the breathing parameters. However, these increased several‐fold during the next days. Hypoxia increased breathing frequency from E18–P5 and only significantly affected ventilation from P3 onwards. At E16, in vitro medullary preparations (pons resection) produced rhythmic phrenic bursts at a low frequency (about 5 cycles/min) with variable cycle duration. At E18, their frequency doubled but cycle duration remained variable. After birth, the frequency did not change although cycle duration stabilised. At E18 and P0–P2, the in vitro frequency decreased by around 50% under hypoxia, increased by 40–50% under noradrenaline or substance P and was permanently depressed by the pontine A5 areas. At E16 however, hypoxia had no effects, both noradrenaline and substance P drastically increased the frequency and area A5 inhibition was not expressed at this time. At E18 and P0–P2, electrical stimulation and electrolytic lesion of the rostral ventrolateral medulla affected the in vitro rhythm but failed to induce convincing effects at E16. Thus, a major maturational step in respiratory rhythmogenesis occurs between E16–E18, in agreement with the concept of multiple rhythmogenic mechanisms.