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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of insect behavior 4 (1991), S. 773-792 
    ISSN: 1572-8889
    Keywords: Delia antiqua ; Anthomyiidae ; Diptera ; herbivore ; egg-laying ; host-finding ; sensory systems ; chemoreception ; n-dipropyl disulfide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Behavioral responses of female onion flies, Delia antiqua (Meigen), to hostplant cues were quantified during encounters of individual flies with onion plants and onion foliar surrogates. The behavioral repertoire of such females included sitting, grooming, running up and down foliar surfaces, extension of the proboscis such that the labellum contacted foliar and soil surfaces, movements of the tip of the abdomen over surfaces (surface probing), subsurface probing of soil crevices with the ovipositor, and oviposition. Sequences of behaviors preceding oviposition were probabilistic rather than highly stereotyped but generally followed the order given above. Foliar surrogates were used to determine the effects of n-dipropyl disulfide (Pr2S2) on the sequence of behaviors leading up to oviposition. The addition of a Pr2S2-treated surrogate to a cage increased the frequency of alighting on that surrogate but also increased alighting on a nearby foliar surrogate without Pr2S2. After alighting, females encountering surrogates treated with Pr2S2 had shorter latencies to proboscis extension and surface probing, spent less time sitting and grooming, and had runs of shorter duration. These females were also more likely to make the transition from probing of surfaces of foliage and soil to subsurface probing of soil crevices and oviposition. Thus, rather than mediating a particular step in the behavioral sequence, Pr2S2 played a role throughout the sequence leading up to oviposition. Collectively, these data and past studies on the onion fly support the hypothesis that egglaying is triggered by a temporal summation of inputs to the central nervous system from various sensory modalities rather than strict behavioral chaining, with each transition effected by some unique cue.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0942-0940
    Keywords: Blood brain barrier ; cerebral blood flow ; intracranial pressure ; arachidonic acid ; brain oedema ; evoked potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Arachidonic acid solution (2 to 15 mg/ml) was infused into the right forebrain white matter of anaesthetised cats over three hours to evaluate its contribution to the genesis and pathophysiology of vasogenic brain oedema. The 0.6 ml infusion increased local white matter water content by a mean of 11.3 ml/100 g tissue but did not increase cortical water content. Histological studies revealed local expansion and trabeculation of the white matter with aggregations of granulocytic neutrophils in the venules and perivenular brain. The adjacent cortical cytoarchitecture was normal. The white matter around the infusion site was stained lightly and over a variable area (15–20 mm2) by intravenously administered Evans Blue dye 2%. Regional cerebral blood flow (rCBF) adjacent to the frontal infusion did not change significantly during the period of infusion and remained similar to rCBF in the contralateral hemisphere. Following the arachidonic acid infusion regional CBF CO2 reactivity was normal and three was no asymmetry of either cortical somatosensory evoked potential (SEP) or motor evoked potential (MEP) waveforms. The increase in brain water content and changes in the ICP and ICP related biodynamics (pressure-volume index, lumped craniospinal compliance and CSF outflow resistance) were similar to those seen following infusion of 0.6 ml saline. These studies suggest that free intraparenchymal arachidonic acid, at concentrations exceeding those occurring in most neuropathological conditions, can increase the normal brain parenchymal capillary permeability but does not disrupt focal cerebrovascular and electrophysiological function. The clinical implications of these findings are discussed.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Acta neurochirurgica 105 (1990), S. 158-168 
    ISSN: 0942-0940
    Keywords: Brain edema ; cerebral blood flow ; brain tissue hydraulic resistance ; somatosensory evoked potential ; intracranial pressure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary To evaluate the potency of putative secondary mediators of brain edema and their possible contribution to edema related brain dysfunction an infusion model of brain edema was developed in rats. 100 ul of fluid (saline, 20% nonautologous protein) was infused over one hour into the left forebrain white matter through a stereotaxically placed (+ 1.2 mm ant to bregma, 3 mm lateral and 2.9 mm depth) 25 G needle. Brain tissue hydraulic resistance (Rt), regional cerebral blood flow (rCBF), cortical somatosensory evoked potentials (SEPs) and intracranial pressure (ICP) (intraventricular needle) were monitored during the infusion and rCBF CO2 reactivity (hydrogen clearance), local brain water content (microgravimetry), BBB integrity (Evans Blue 2%) and brain histology (H & E, Solochrome-cyanin) were evaluated after the infusion. Saline infusates caused no physiological dysfunction despite ipsilateral expansion and vacuolation of the subcortical white matter, separation of axonal bundles and a significant decrease (p=3.8×10−5)in local subcortical tissue specific gravity. Cortical histology and specific gravity adjacent to the infusion locus were normal. Rt significantly decreased (p=6.5×10−4) during the infusion but there were only minor increases in ICP. Findings with 20% protein infusates were similar despite a focal 65% decrement in the rCBF CO2 reactivity adjacent to the infusion site. This study has shown that a simple and inexpensive model of infusion brain edema can be created in the rat and that it provides a useful model for assessing the physiological effects of mediator compounds in the infusate. Potential applications and methodological improvements for this model are discussed.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Acta neurochirurgica 115 (1992), S. 53-59 
    ISSN: 0942-0940
    Keywords: Bradykinin ; intracranial pressure ; evoked potentials ; cerebral blood flow ; brain edema ; blood brain barrier
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The feline infusion model of brain edema was used to evaluate the role of bradykinin in the etiology and pathophysiology of vasogenic brain edema. Bradykinin (3 or 90 ug in 600 μL saline) did not alter normocapnic regional cerebral blood flow (rCBF) nor induce specific changes in either the somatosensory (SEP) or motor (MEP) evoked potentials. The mean increases in ICP (from 4.5 to 16.1 mmHg) and peri-infusion white matter water content (from 69.4 to 79.8 ml/100 g tissue), mean decrease in lumped craniospinal compliance (from 0.040 to 0.014 ml/mmHg) and local histological changes were all similar to those after 600 μL saline infusion. The interstitial bradykinin infusion caused focal blood-brain-barrier (BBB) opening to Evans Blue dye and was chemotaxic for granulocytes. After the infusion there was a global loss of rCBF CO2 reactivity but there was no ischemia at normocapnia. These results show that bradykinin in brain edema fluid, at concentrations greater than those found in neuropathological conditions, can open the BBB of normal cerebral parenchymal capillaries and cause vascular dysregulation. In neuropathological conditions bradykinin may therefore potentiate formation of vasogenic brain edema but does not contribute to perilesional brain dysfunction.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0942-0940
    Keywords: Brain edema ; blood brain barrier ; serum protein ; evoked potential ; glioma ; cerebral blood flow ; permeability factor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The feline infusion model of brain edema was used to evaluate the pathophysiological effects of 0.6ml infusions of autologous serum protein (66%), human serum protein (66%), human glioma cyst fluid and a tissue culture medium (TCM) on the structure and function of the forebrain white matter. These infusions increased local white matter water content by between 10.8 and 12.5 ml/100 g brain and were associated with moderate increases in ICP and CSF outflow resistance and a significant decrease in lumped craniospinal compliance. Cortical somatosensory potentials, motor evoked potentials, EEG and local cerebral blood flow (rCBF) at normocapnia were generally unchanged by the various infusions. All infusates except the 66% autologous serum protein infusion impaired rCBF CO2 reactivity. Histologically all infusates caused marked extracellular edema. The autologous serum protein infusion caused no additional histological changes whereas the glioma cyst infusates caused profound endothelial and astrocytic swelling, focal endothelial necrosis, basement membrane disruption, perivascular microglial reaction and pavementation and perivascular migration of polymor-phonuclear leukocytes. Similar but less marked changes were seen after infusion of human serum protein whilst the TCM produced only minimal changes. The intensity and extent of Evans Blue extravasation into the forebrain white matter was greatest with glioma cyst infusates and with all infusions reflected the extent to microvascular changes. These studies show that products derived from gliomas cause additional damage to the blood-brain-barrier than that caused by non-autologous serum proteins. These results add further support for the existence of glioma derived permeability factors (GDPF), but suggest neither serum proteins nor glioma derived compounds in the white matter interstitium significantly influence local electrophysiological function. Some limitations of the infusion edema model when using non-autologous infusions and difficulties quantitating brain dysfunction are emphasised.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 56 (1984), S. 243-256 
    ISSN: 1432-1106
    Keywords: Medial septum ; Hippocampus ; Dentate gyrus ; Evoked potentials
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Previous electrophysiological experiments in rabbits have suggested that medial septal stimulation activates dentate granule cells and evokes an associated negative field response at the granule cell layer, without an associated “dendritic” response. Anatomical studies have suggested that septal input to the granule cells may be to stratum moleculare, or close to the cell layer, or may not exist at all. The present experiments confirmed in rats anaesthetised with urethane that medial septal stimulation elicits single action potentials from cells in the granule layer. The associated negative field potential was maximal in the granule cell layer and there was no sign of a separate dendritic potential. The fibres responsible for this potential travel to the dorsal hippocampus in the fornix superior rather than the fimbria, taking the same course as the fibres which contribute to the dense cholinesterase staining just above the granule cell layer. Stimulation at 100 Hz for 1 s of either medial septal, or perforant path, input to the dentate granule cell layer produced long term potentiation of the subsequent evoked field responses to the stimulated pathway. The responses to the non-stimulated pathway were unchanged. Paired pulse stimulation produced both homosynaptic and heterosynaptic potentiation. These data suggest that medial septal input synapses close to granule cell bodies and produces a negative field potential which is a combination of dendritic and population spike potentials. Medial septal input also appeared to produce direct activation of hilar neurones, some of which may be basket cells or other interneurones. The data also show that long term potentiation is specific to this input, perhaps dependent on presynaptic mechanisms. Paired pulse potentiation, at least in the heterosynaptic case appears to depend on postsynaptic mechanisms.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 54 (1984), S. 567-570 
    ISSN: 1432-1106
    Keywords: Hippocampus ; Frequency potentiation ; Transmembrane potential ; Ephaptic transmission
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The contribution of ephaptic interactions to potentiation of the hippocampal CA1 extracellular population spike during paired pulse or frequency stimulation of stratum radiatum (SR) inputs was investigated using the in vitro hippocampal slice preparation. Records of the transmembrane potential revealed a depolarizing wave with an amplitude and latency that varied directly with that of the extracellular population spike. Paired pulse or repetitive stimulation of SR resulted in a potentiation of the population spike amplitude and a corresponding increase in the amplitude of the TMP depolarizing wave. Action potentials generated during the stimulus train consistently arose from the peak of the depolarizing wave. It is proposed that ephaptic interactions contribute to potentiation of the extracellular population spike through recruitment of subthreshold neurons within the population during repetitive afferent stimulation.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 62 (1986), S. 250-258 
    ISSN: 1432-1106
    Keywords: Longterm potentiation ; Hippocampus ; Collateral specificity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Long term potentiation (LTP) in response to brief high frequency trains has been reported for many pathways in the hippocampus. The mechanisms involved are still unclear. The present experiments set out to confirm reports in the literature that LTP of output from CA3 neurons can be specific to particular collaterals. Single pulses delivered to area CA3 produced field responses nearly simultaneously in area CA1 and in the lateral septum (LS). High frequency stimulation of CA3 produced long term potentiation of CA1 but not LS responses. The CA1 response to stimulation of the contralateral hippocampus did not potentiate when the CA1 response to CA3 stimulation showed long term potentiation. The CA1 and LS responses to CA3 stimulation showed similar strength-duration, strength-amplitude and frequency following characteristics. Their latencies were comparable to the latencies of antidromic activation of CA3 cells from CA1 and LS. Movement of stimulating electrodes to the region of the Schaffer collaterals increased the latency of the LS response and decreased the latency of the CA1 response but left the sum of these latencies unchanged. It was concluded that the CA3 and Schaffer stimulation were activating LS and CA1 collaterals of the same CA3 neurons. CA1 and LS responses to CA3 stimulation showed somewhat different paired pulse and frequency potentiation characteristics. These data confirm reports in the literature that long term potentiation is both input-specific and collateral-specific. The mechanisms of long term potentiation are likely, therefore, to be limited to changes at specific synaptic junctions, e.g. changes in sensitivity of specific postsynaptic receptor sites or changes in transmitter release, which can depend on functional or organisational differences between two collaterals of the same neuron.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 57 (1985), S. 443-447 
    ISSN: 1432-1106
    Keywords: Epilepsy ; GABA ; Hippocampus ; Inhibition ; Kindling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In vitro hippocampal slices were prepared from control and commissural-kindled rats and the inhibitory processes of the dentate granule cells were assessed using paired perforant path stimulation. An early (20 ms) Cl--dependent and a late (200 ms-8 s) Cl--independent inhibition were shown to be present in the dentate. Enhancement of the late Cl--insensitive inhibition was observed following the establishment of commissural kindling and persisted for periods of up to eight weeks following the last seizure.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical ecology 15 (1989), S. 719-730 
    ISSN: 1573-1561
    Keywords: Onion fly ; Delia antiqua ; Diptera ; Anthomyiidae ; oviposition ; deterrent ; capsaicin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract In laboratory choice experiments, the spices dill, paprika, black pepper, chili powder, ginger, and red pepper deterredDelia antiqua oviposition by 88–100%. Dose-response choice tests demonstrated that 1 mg of ground cayenne pepper (GCP) placed within 1 cm of artificial onion foliage reduced oviposition by 78%. A synthetic analog of capsaicin, the principal flavor ingredient of red peppers, deterred oviposition by 95% when present at 320 ppm in the top centimeter of sand (the ovipositional substrate). However, in no-choice conditions 10 mg GCP was not an effective deterrent. Sevana Bird Repellent and Agrigard Insect Repellent both use red pepper as a principal ingredient; at recommended field rates, neither of these materials was an effective ovipositional deterrent either in laboratory or field. Capsaicin-based materials do not appear to be candidates for onion maggot control via behavioral modification.
    Type of Medium: Electronic Resource
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