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  • 1
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    Neuronal repair. Asynchronous therapy restores motor control by rewiring of the rat corticospinal tract after stroke (2014)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2014-06-14
    Description: The brain exhibits limited capacity for spontaneous restoration of lost motor functions after stroke. Rehabilitation is the prevailing clinical approach to augment functional recovery, but the scientific basis is poorly understood. Here, we show nearly full recovery of skilled forelimb functions in rats with large strokes when a growth-promoting immunotherapy against a neurite growth-inhibitory protein was applied to boost the sprouting of new fibers, before stabilizing the newly formed circuits by intensive training. In contrast, early high-intensity training during the growth phase destroyed the effect and led to aberrant fiber patterns. Pharmacogenetic experiments identified a subset of corticospinal fibers originating in the intact half of the forebrain, side-switching in the spinal cord to newly innervate the impaired limb and restore skilled motor function.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wahl, A S -- Omlor, W -- Rubio, J C -- Chen, J L -- Zheng, H -- Schroter, A -- Gullo, M -- Weinmann, O -- Kobayashi, K -- Helmchen, F -- Ommer, B -- Schwab, M E -- New York, N.Y. -- Science. 2014 Jun 13;344(6189):1250-5. doi: 10.1126/science.1253050.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Health Sciences and Technology, ETH Zurich, Zurich, Switzerland. Brain Research Institute, University of Zurich, Zurich, Switzerland. schwab@hifo.uzh.ch wahl@hifo.uzh.ch. ; Brain Research Institute, University of Zurich, Zurich, Switzerland. ; Computer Vision Group, Heidelberg Collaboratory for Image Processing and Interdisciplinary Center for Scientific Computing (IWR), University of Heidelberg, Heidelberg, Germany. ; Institute for Biomedical Engineering, ETH Zurich, Zurich, Switzerland. ; Department of Health Sciences and Technology, ETH Zurich, Zurich, Switzerland. Brain Research Institute, University of Zurich, Zurich, Switzerland. ; National Institute for Physiological Sciences, National Institute of Natural Sciences Myodaiji, Okazaki, Japan.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24926013" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Female ; Immunotherapy/methods ; Motor Cortex/*physiopathology ; Myelin Proteins/*antagonists & inhibitors ; Physical Conditioning, Animal ; Prosencephalon/physiopathology ; Pyramidal Tracts/*injuries/*physiology ; Rats ; Rats, Long-Evans ; *Recovery of Function ; Stroke/*rehabilitation
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 2
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    Do quantitative vessel and pit characters account for ion-mediated changes in the hydraulic conductance of angiosperm xylem? (2011)
    In:  New Phytologist vol. 189, pp. 218-228
    Details
    Publication Date: 2024-01-12
    Description: \xe2\x80\xa2 The hydraulic conductance of angiosperm xylem has been suggested to vary with changes in sap solute concentrations because of intervessel pit properties.\n\xe2\x80\xa2 The magnitude of the \xe2\x80\x98ionic effect\xe2\x80\x99 was linked with vessel and pit dimensions in 20 angiosperm species covering 13 families including six Lauraceae species.\n\xe2\x80\xa2 A positive correlation was found between ionic effect and vessel grouping parameters, especially the portion of vessel walls in contact with neighbouring vessels. Species with intervessel contact fraction (FC) values 〈 0.1 showed an ionic effect between 2% and 17%, while species with FC values 〉 0.1 exhibited a response between 10% and 32%. The ionic effect increased linearly with the mean fraction of the total vessel wall area occupied by intervessel pits as well as with the intervessel contact length. However, no significant correlation occurred between the ionic effect and total intervessel pit membrane area per vessel, vessel diameter, vessel length, vessel wall area, and intervessel pit membrane thickness.\n\xe2\x80\xa2 Quantitative vessel and pit characters are suggested to contribute to interspecific variation of the ionic effect, whereas chemical properties of intervessel pit membranes are likely to play an additional role.
    Keywords: angiosperms ; hydraulic conductivity ; intervessel pit membrane ; ionic effect ; vessel grouping ; wood anatomy
    Repository Name: National Museum of Natural History, Netherlands
    Type: info:eu-repo/semantics/article
    Format: application/pdf
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  • 3
    Electronic Resource
    Electronic Resource
    Different vulnerabilities of Quercus ilex L. to freeze- and summer drought-induced xylem embolism: an ecological interpretation (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 16 (1993), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Quercus ilex L. growing in the southern Mediterranean Basin region is exposed to xylem embolism induced by both winter freezing and summer drought. The distribution of the species in Sicily could be explained in terms of the different vulnerability to embolism of its xylem conduits. Naturally occurring climatic conditions were simulated by: (1) maintaining plants for 3h at ambient temperatures of 0, -1.5, -2.5, -5.0 and -11°C; and (2) allowing plants to dry out to ratios of their minimum diurnal leaf water potentials (Ψ1) to that at the turgor loss point (Ψtlp) of 0.6, 0.9, 1.05, 1.20 and 1.33. The loss of hydraulic conductivity of one-year-old twigs reached 40% at -1.5°C and at Ψ1/ΨtlP= 1.05. Recovery from these strains was almost complete 24 h after the release of thermal stress or after one irrigation, respectively. More severe stresses reduced recovery consistently. The percentages of xylem conduits embolized following application of the two stresses, were positively related to xylem conduit diameter. The capability of the xylem conduits to recover from stress was positively related to the conduit diameter in plants subjected to summer drought, but not in the plants subjected to winter freezing stress. The ecological significance of the different vulnerabilities to embolism of xylem conduits under naturally occurring climatic conditions is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1993.tb00898.x
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  • 4
    Electronic Resource
    Electronic Resource
    Vulnerability to cavitation of leaf minor veins: any impact on leaf gas exchange? (2001)
    Oxford, UK : Blackwell Science Ltd
    Plant, cell & environment 24 (2001), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Vulnerability to cavitation of leaf minor veins and stems of Laurus nobilis L. was quantified together with that of leaflets, rachides and stems of Ceratonia siliqua L. during air-dehydration of 3-year-old branches. Embolism was estimated by counting ultrasound acoustic emissions (UAE) and relating them to leaf water potential (ΨL). The threshold ΨL for cavitation was less negative in L. nobilis than in C. siliqua according to the known higher drought resistance of the latter species. Leaf minor vein cavitation was also quantified by infiltrating leaves with fluorescein at different dehydration levels and observing them under microscope. Distinct decreases in the functional integrity of minor veins were observed during leaf dehydration, with high correlation between the two variables. The relationship between leaf conductance to water vapour (gL) and ΨL showed that stomata of L. nobilis closed in response to stem and not to leaf cavitation. However, in C. siliqua, gL decreased in coincidence to the leaf cavitation threshold, which was, nevertheless, very close to that of the stem. The hypothesis that stem cavitation acts as a signal for stomatal closure was confirmed, while the same role for leaf cavitation remains an open problem.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.0016-8025.2001.00734.x
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  • 5
    Electronic Resource
    Electronic Resource
    Competitive strategies for water availability in two Mediterranean Quercus species (1999)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 22 (1999), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Competition for water availability was studied in a mixed natural stand of Quercus suber L. and Quercus cerris L. growing in Sicily by measuring diurnal changes of leaf conductance to water vapour (gL), water potential (ΨL) and relative water content (RWC) in April, July and October 1997 as well as the seasonal changes in root hydraulic conductance per unit leaf surface area (KRL). Quercus cerris behaved as a drought-tolerant species, with strong reductions of KRL, ΨL, and RWC in the summer. By contrast, Q. suber appeared to withstand summer drought by an avoidance strategy based on reducing gL, maintaining ΨL and RWC high and KRL at the same level as that measured in the spring. A ‘conductance ratio’ (CR) was calculated in terms of the ratio of gL to KRL. Seasonal changes of this ratio contrasted in the two species, thus suggesting that Q. suber and Q. cerris did not really compete for available water. In the summer, when Q. suber was extracting water from the soil to maintain high leaf hydration, Q. cerris had restricted water absorption, thus suffering drought but tolerating its effects. The possibility that cohabitation of drought-tolerant with drought-avoiding species can be generalized is also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3040.1999.00382.x
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  • 6
    Electronic Resource
    Electronic Resource
    Ultrasound acoustic emissions from dehydrating leaves of deciduous and evergreen trees (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 20 (1997), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: While drying, detached leaves produced ultrasound acoustic emissions (UAE) comparable to emissions from stem and twig wood. Experiments on Ilex aquifolium L. showed that the main source of these signals was cavitation in the veins, to which conduits and fibres probably both contributed. Regions of the leaf blade with abundant mesophyll and only small veins emitted few signals. More signals were counted on the adaxial side of the midrib than on the abaxial one and on the proximal third than on the distal one, in accordance with the anatomical structure. Sound attenuation was pronounced. Eight species were compared with respect to cavitation behaviour, field water relations and pressure–volume curves, and the data showed differences in cumulative number of events and resistance of leaves to cavitation. Data were generally in good agreement with anatomical structure and habitat preferences. The number of signals per conduit counted on cross-sections was in some leaves much higher than unity, which suggests short xylem elements or an acoustic activity of cells other than conduits. There was no correlation between cavitation threshold or cumulative number of signals and the degree of sclerophylly; unexpectedly, there was a correlation between the cumulative number of signals at a water potential of -1.3 MPa and the bulk modulus of elasticity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3040.1997.d01-34.x
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  • 7
    Electronic Resource
    Electronic Resource
    Relations between vulnerability to xylem embolism and xylem conduit dimensions in young trees of Quercus corris (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 18 (1995), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Measurements of xylem conduit length and width and the distribution of xylem conduit ends were made in inter-nodes (I), nodes (N) and twig junctions (J) of 1-, 2- and 3-year-old twigs of plants of Quercus cerris L. Parallel measurements were also made of the loss of hydraulic conductivity of twigs subjected to pressure differentials across conduit pit membranes, equalling the leaf water potential at the turgor loss point. The loss of theoretical hydraulic conductivity was calculated as the ratio of i esivr4 (where r is the conduit radius) of the non-conducting conduits to that of all the conduits in the outermost wood ring of I, N and J. Stem zones such as 1-year-old nodes and junctions were localized with narrower and shorter xylem conduits and with higher percentages of conduit ends than internodes. Such ‘constricted zonesrsquo; were less vulnerable to embolism than internodes. Latewood conduits were consistently narrower, shorter and less vulnerable to embolism than earlywood ones. A positive relation therefore existed between conduit diameter and length and vulnerability to embolism. The overall vulnerability to embolism of Q. cerris plants is discussed in terms of xylem conduit width and length and of the distribution of conduit ends.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1995.tb00567.x
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  • 8
    Electronic Resource
    Electronic Resource
    New evidence for a role of vessel-associated cells and phloem in the rapid xylem refilling of cavitated stems of Laurus nobilis L. (2004)
    Oxford, UK : Blackwell Science Ltd
    Plant, cell & environment 27 (2004), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Xylem recovery from embolism was studied in Laurus nobilis L. stems that were induced to cavitate by combining negative xylem pressure potentials (PX = −1.1 MPa) with positive air pressures (PC) applied using a pressure collar. Xylem refilling was measured by recording the percentage loss of hydraulic conductance (PLC) with respect to the maximum 2 min, 20 min and 15 h after pressure release. Sodium orthovanadate (an inhibitor of many ATP-ases) strongly inhibited xylem refilling while fusicoccin (a stimulator of the plasma membrane H+-ATPase) promoted complete embolism reversal. So, the refilling process was interpreted to result from energy-dependent mechanisms. Stem girdling induced progressively larger inhibition to refilling the nearer to the embolized stem segment phloem was removed. The starch content of wood parenchyma was estimated as percentages of ray and vasicentric cells with high starch content with respect to the total, before and after stem embolism was induced. A closely linear positive relationship was found to exist between recovery from PLC and starch hydrolysis. This, was especially evident in vasicentric cells. A mechanism for xylem refilling based upon starch to sugar conversion and transport into embolized conduits, assisted by phloem pressure-driven radial mass flow is proposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.2004.01211.x
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  • 9
    Electronic Resource
    Electronic Resource
    Water storage in the wood and xylem cavitation in 1-year-old twigs of Populus deltoides Bartr. (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 15 (1992), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The possible role of water expelled from cavitated xylem conduits in the rehydration of water-stressed leaves has been studied in one-year-old twigs of populus deltoides Bartr. Twigs were dehydrated in air. At desired values of leaf water potential (Ψl) (between near full turgor and -1.62 MPa), twigs were placed in black plastic bags for 1–2h. Leaf water content was measured every 3–5 min before bagging and every 10 min in the dark. Hydraulic conductivity and xylem cavitation were measured both in the open and in the dark. Cavitation was monitored as ultrasound acoustic emissions (AE). A critical Ψl value of -0.96 MPa was found, at which AE increased significantly while the leaf water deficit decreased by gain of water. Since the twigs were no longer attached to roots, it was concluded that water expelled from cavitated xylem conduits was transported to the leaves, thus contributing to their rehydration. Xylem cavitation is discussed in terms of a ‘leaf water deficit buffer mechanism’, under not very severe water stress conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1992.tb00993.x
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  • 10
    Electronic Resource
    Electronic Resource
    A method for inducing xylem emboli in situ: experiments with a field-grown tree (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 15 (1992), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A pressure collar, assembled around 25cm sections of 4-year-old willow twigs, was used to examine cavitation events under field conditions. When the air pressure inside the collar was raised to between 1–8 and 2–8MPa, ultrasound acoustic emission signals were triggered which indicated the breaking of water columns in the xylem. The hydraulic conductivity of the twig portion inside the chamber decreased markedly. As a result, water potentials and conductances in leaves at the end of the twig decreased. Similar changes were induced at comparable pressures in detached twigs. The equipment used is described in detail, and evidence is presented that the mechanism of this artificial production of emboli follows the air-seeding principle hypothesized for natural cavitation events.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1992.tb01001.x
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