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  • 1
    Electronic Resource
    Electronic Resource
    The performance of the octopus circulatory system: A triumph of engineering over design (1987)
    Springer
    Cellular and molecular life sciences 43 (1987), S. 487-499 
    Details
    ISSN: 1420-9071
    Keywords: Octopus ; circulatory physiology ; exercise ; hypoxia ; cardiac control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Despite the very considerable difficulties presented by the basic molluscan anatomy and the possession of a blood pigment with an oxygen carrying capacity that never exceeds 4.5 vols%, the cephalopod circulatory system contrives to deliver oxygen at a rate fully comparable with that of an active fish. This is achieved by adding accessory pumps to push blood through the gills, by a multiplicity of pulsatile veins and by raising the systemic blood pressure considerably above the levels found in other molluscs. Detailed control of blood distribution is a necessity in a system where the peripheral resistences may be expected to change dramatically when the animal starts to move and large parts of the central nervous system are apparently dedicated to this task. In this account we have reviewed blood pressure and flow at rest and in exercise. We have further examined the evidence which indicates how the animals modulate the cardiac output, drawing attention to the very different response found in cephalopods and the higher vertebrates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02143577
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  • 2
    Electronic Resource
    Electronic Resource
    Cardiac output in the Mollusca: Scope and regulation (1987)
    Springer
    Cellular and molecular life sciences 43 (1987), S. 956-965 
    Details
    ISSN: 1420-9071
    Keywords: Mollusca ; cardiac output ; cardiac regulation ; 5-HT ; ACh ; FMRFamide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Different molluscan groups have evolved functionally specialised cardiovascular systems in response to varied behavioural and environmental demands, making the study of cardiovascular regulation in these animals a fascinating area for research. Currently, such research is frustrated by the lack of data on the in vivo performance of these systems, although, where examined, increased cardiac output appears to be accommodated by a change in stroke volume. This paper considers the in vivo regulation of cardiac output, primarily by extrapolating from in vivo experiments, and proposes the following three hypotheses for future study. 1. The increase in stroke volume is critically dependent on the phasic action of acetylcholine, expanding the end-diastolic volume of the ventricle for the same returning venous pressure. 2. Circulating cardioactive peptides will set the level of myocardial tone on a sliding scale, against which the action of both intrinsic and extrinsic factors are expressed. 3. In extreme cases, the inherent myogenicity of the heart may depend on the level of a circulating peptide. Here, the organ might be better described as humourogenic, rather than myogenic.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01952210
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  • 3
    Electronic Resource
    Electronic Resource
    Multitip scanning bio-Kelvin probe (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 1842-1850 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We have developed a novel multitip scanning Kelvin probe which can measure changes in biological surface potential ΔVs to within 2 mV and, quasisimultaneously monitor displacement to 〈1 μm. The control and measurement subcomponents are PC based and incorporate a flexible user interface permitting software control of each individual tip, measurement, and scan parameters. We review the mode of operation and design features of the scanning bio-Kelvin probe including tip steering, signal processing, tip calibration, and novel tip tracking/dithering routines. This system uniquely offers both tip-to-sample spacing control (which is essential to avoid spurious changes in ΔVs due to variations in mean spacing) and a dithering routine to maintain tip orientation to the biological specimen, irrespective of the latter's movement. These features permit long term (〉48 h) "active" tracking of the displacement and biopotentials developed along and around a plant shoot in response to an environmental stimulus, e.g., differential illumination (phototropism) or changes in orientation (gravitropism). © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149678
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  • 4
    Electronic Resource
    Electronic Resource
    Single-cell, real-time measurements of extracellular oxygen and proton fluxes fromSpirogyra grevilleana (2000)
    Springer
    Protoplasma 212 (2000), S. 80-88 
    Details
    ISSN: 1615-6102
    Keywords: Alternative oxidase ; Photosynthesis ; Respiration ; Self-referencing microelectrode ; Spirogyra gre illeana ; Vibrating probe
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have adapted the self-referencing microelectrode technique to allow sensitive and noninvasive measurement of oxygen fluxes around single cells. The self-referencing technique is based on the translational movement of a selective microelectrode through the gradient next to the cell wall or membrane. The electrode is moved at a known frequency and between known points. The differential electrode output values are converted into a directional measurement of flux by the Fick equation. By coupling the newly developed oxygen-selective self-referencing electrochemical microelectrode (SREM-O2) system with self-referencing ionselective proton measurements (SRIS-H+) we have characterized oxygen and proton fluxes from a single cell of the filamentous green algaSpirogyra gre illeana (Hass.). Oxygen showed a net efflux and protons showed a net influx when the cell was illuminated. These photosynthesis-dependent fluxes were found to be spatially associated with the chloroplasts and were sensitive to treatment with dichlorophenyldimethylurea. In the dark the directions of oxygen and proton fluxes were reversed. This oxygen influx was associated with mitochondrial respiration and was reduced by 78% when the cells was treated with 0.5 mM KCN. The residual cyanide-resistant respiration was inhibited by the application of 5 mM salicylhydroxamic acid, an inhibitor of the alternative oxidase. Similarly the cytochrome pathway was also inhibited by the presence of 20 μM NO, while the cyanide-resistant alternative oxidase was not. These results demonstrate the use of the newly developed SREM-O2 system to measure and characterize metabolic fluxes at a level of sensitivity that allows for subcellular resolution. These measurements, in conjunction with SERIS-H+ measurements, have led to new insights in our understanding of basic cellular physiology in plant cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01279349
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  • 5
    Electronic Resource
    Electronic Resource
    A non-invasive vibrating calcium-selective electrode measures acetylcholine-induced calcium flux across the sarcolemma of a smooth muscle (1996)
    Springer
    Journal of comparative physiology 166 (1996), S. 270-277 
    Details
    ISSN: 1432-136X
    Keywords: Ca2+ channel blockers ; Cobalt chloride ; Diltiazem ; Excitation-contraction coupling ; Lanthanum chloride ; Smooth muscle ; Verapamil ; Vibrating Ca2+-selective electrode
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract To determine possible sources of Ca2+ during excitation-contraction coupling in smooth muscle, a vibrating Ca2+-selective electrode was used to measure Ca2+ flux during the process of contraction. The smooth muscle model was the longitudinal muscle of the body wall of a sea cucumberSclerodactyla briareus. Because acetylcholine caused slow contractions of the muscle that were inhibited by Ca2+ channel blockers diltiazem and verapamil in earlier mechanical studies, we chose a vibrating Ca2+-selective electrode as our method to test the hypothesis that acetylcholine may be stimulating Ca2+ influx across the sarcolemma, providing a Ca2+ source during excitation-contraction coupling. Acetylcholine treatment stimulated a net Ca2+ efflux that was both dose and time dependent. We then tested two L-type Ca2+ channel blockers, diltiazem and verapamil, and two non-specific Ca2+ blockers, cobalt (Co2+) and lanthanum (La3+) on acetylcholine-induced Ca2+ flux. All four Ca2+ blockers tested potently inhibited Ca2+ efflux induced by physiological doses of acetylcholine. We propose that the acetylcholine-induced Ca2+ efflux was the result of, first, Ca2+ influx through voltage-sensitive L-type Ca2+ channels, then the rapid extrusion of Ca2+ by an outwardly directed carrier such as the Na−Ca exchanger as suggested by Li+ substitution experiments. The vibrating Ca2+ electrode has provided new insights on the active and complex role the sarcolemma plays in Ca2+ homeostasis and regulating Ca2+ redistribution during excitation-contraction coupling.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00262871
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  • 6
    Electronic Resource
    Electronic Resource
    Haemocyte involvement in the repair of the insect central nervous system after selective glial disruption (1986)
    Springer
    Cell & tissue research 243 (1986), S. 367-374 
    Details
    ISSN: 1432-0878
    Keywords: Haemocytes ; Glia ; Central nervous system ; Repair ; Insect ; Periplaneta americana
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Injection of physiologically inert particles (fluorescent microspheres) has a profound effect on neural repair of central nervous connectives of the cockroach Periplaneta americana following selective glial disruption. The injected particles, which do not gain direct access to the central nervous tissues, are taken up by a relatively small proportion (〈 10%) of the haemocytes. This interference with haemocyte function virtually abolishes the appearance of the granule-containing cells (which are prominently involved in normal glial repair) and produces abnormal reorganization of the superficial glial elements. These results are interpreted as evidence that the granule-containing cells are derived from haemocytes which are critically involved in glial repair.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00251053
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  • 7
    Electronic Resource
    Electronic Resource
    The effects of an anti-mitotic drug, bleomycin, on glial repair in an insect central nervous system (1986)
    Springer
    Cell & tissue research 243 (1986), S. 375-384 
    Details
    ISSN: 1432-0878
    Keywords: Glia ; Haemocyte ; Central nervous system ; Bleomycin ; Neural repair ; Insect, Periplaneta americana
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The DNA-binding drug, bleomycin, has a profound effect on neural repair following selective glial disruption by ethidium bromide. The contribution of the granule-containing cells (which normally appear in the early stages of repair) is greatly reduced, the restoration of the blood-brain barrier is delayed and the ultrastructural organization of the reorganising perineurium is dramatically changed. The aberrant perineurial structure and function observed in the presence of bleomycin are postulated to result from the effects of the drug on haemocytes which, together with endogenous reactive cells, contribute to the normal process of glial repair.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00251054
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  • 8
    Electronic Resource
    Electronic Resource
    Neural repair in an insect central nervous system: cell kinetics and proliferation after selective glial disruption (1987)
    Springer
    Cell & tissue research 247 (1987), S. 129-135 
    Details
    ISSN: 1432-0878
    Keywords: Neural repair ; Glia ; Haemocytes ; Cell division ; Insect, Periplaneta americana
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Autoradiographs of tritiated thymidine uptake and subsequent light- and electron-microscopical examination revealed an onset of perineurial glial cell proliferation 3 days after injury to the CNS. The number of cells labelled increased rapidly until 7 days post-lesioning. At 2 weeks, the labelled cells equalled the number of nuclei present in the perineurium. No label was seen in the subperineurial cells, possibly because of the inability of the label to penetrate into a region where localised division is taking place. Prior to the onset of thymidine uptake, the damaged nerve cord was invaded by an exogenous reactive cell. The number of these cells increased rapidly in the first 48 h, then decreased as a negative exponential, very few remaining after 7 days. We suggest that this cell type must either return to the haemocoel or transform into a functional glial cell class. The repair of the insect central nervous system can be divided into three phases which show striking similarities to vertebrate repair sequences. These include: initial invasion of the lesion by exogenous cells, subsequent proliferation of glial cells, the longer term flux of cell numbers, their distribution and the time scale of events. This suggests that the insect CNS might provide a system for examining common cellular mechanisms and events.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00216555
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  • 9
    Electronic Resource
    Electronic Resource
    Cell recruitment during glial repair: the role of exogenous cells (1988)
    Springer
    Cell & tissue research 251 (1988), S. 339-343 
    Details
    ISSN: 1432-0878
    Keywords: Glia ; Neural repair ; CNS ; Insect, Periplaneta americana
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Selective disruption of the neuroglia in penultimate abdominal connectives of the cockroach nerve is followed by a rapid accumulation of cells in the perineurial layer of the lesion. Subsequently, there is an abrupt, secondary, rise in cell numbers in the undamaged perineurial tissues, anterior to the lesion and adjacent to the 4th abdominal ganglia. By 7 days the increased cell numbers are again effectively confined to the original lesion zone. The initial rise in cell numbers is postulated to result from an invasion by blood-borne haemocytes and the subsequent increase, in undamaged perineurial tissues, from the mobilization of endogenous reactive cells. Recruitment of the endogenous cells is inhibited if the haemocytes are excluded from the lesion. There is a slower mobilization of sub-perineurial cells, which, again, is inhibited following exclusion of haemocytes from the lesion zone. It is postulated that the recruitment of the endogenous reactive cells is initiated by the invading haemocytes which transform to granule-containing cells and release diffusible morphogenic and/or mitogenic factors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00215842
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  • 10
    Electronic Resource
    Electronic Resource
    Cell specific DNA-labelling in the repairing blood-brain barrier of the insect Periplaneta americana (1992)
    Springer
    Cell & tissue research 267 (1992), S. 535-543 
    Details
    ISSN: 1432-0878
    Keywords: Blood-brain barrier ; Neural regeneration ; BUdR ; Glia ; Cell proliferation ; Periplaneta americana (Insecta)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary This study uses a recently developed technique for preserving the ultrastructure of cells in the insect CNS during immunohistochemical processing for 5-bromo-2-deoxyuridine incorporation into newly synthesised DNA. The results allow us to identify the proliferating cell calsses in the regenerating blood-brain barrier. High resistance barrier cells do not label with the antibody but sheath cells clearly do. Intermediate cell types appearing during repair are identified. It is hypothesised that these cells generate matrix molecules for neural lamella repair and may represent transitional forms as invasive blood cells transdifferentiate into functional sheath cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00319376
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