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  • 1
    Online Resource
    Online Resource
    American Physiological Society ; 2011
    In:  American Journal of Physiology-Lung Cellular and Molecular Physiology Vol. 301, No. 1 ( 2011-07), p. L110-L116
    In: American Journal of Physiology-Lung Cellular and Molecular Physiology, American Physiological Society, Vol. 301, No. 1 ( 2011-07), p. L110-L116
    Abstract: Diaphragm muscle weakness in patients with chronic obstructive pulmonary disease (COPD) is associated with increased morbidity and mortality. Recent studies indicate that increased contractile protein degradation by the proteasome contributes to diaphragm weakness in patients with COPD. The aim of the present study was to investigate the effect of proteasome inhibition on diaphragm function and contractile protein concentration in an animal model for COPD. Elastase-induced emphysema in hamsters was used as an animal model for COPD; normal hamsters served as controls. Animals were either treated with the proteasome inhibitor Bortezomib (iv) or its vehicle saline. Nine months after induction of emphysema, specific force-generating capacity of diaphragm bundles was measured. Proteolytic activity of the proteasome was assayed spectrofluorometrically. Protein concentrations of proteasome, myosin, and actin were measured by means of Western blotting. Proteasome activity and concentration were significantly higher in the diaphragm of emphysematous hamsters than in normal hamsters. Bortezomib treatment reduced proteasome activity in the diaphragm of emphysematous and normal hamsters. Specific force-generating capacity and myosin concentration of the diaphragm were reduced by ∼25% in emphysematous hamsters compared with normal hamsters. Bortezomib treatment of emphysematous hamsters significantly increased diaphragm-specific force-generating capacity and completely restored myosin concentration. Actin concentration was not affected by emphysema, nor by bortezomib treatment. We conclude that treatment with a proteasome inhibitor improves contractile function of the diaphragm in emphysematous hamsters through restoration of myosin concentration. These findings implicate that the proteasome is a potential target of pharmacological intervention on diaphragm weakness in COPD.
    Type of Medium: Online Resource
    ISSN: 1040-0605 , 1522-1504
    Language: English
    Publisher: American Physiological Society
    Publication Date: 2011
    detail.hit.zdb_id: 1477300-4
    SSG: 12
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  • 2
    Online Resource
    Online Resource
    American Physiological Society ; 2005
    In:  American Journal of Physiology-Lung Cellular and Molecular Physiology Vol. 288, No. 1 ( 2005-01), p. L16-L26
    In: American Journal of Physiology-Lung Cellular and Molecular Physiology, American Physiological Society, Vol. 288, No. 1 ( 2005-01), p. L16-L26
    Abstract: Oxidants may play a role in hypoxia-induced respiratory muscle dysfunction. In the present study we hypothesized that hypoxia-induced impairment in diaphragm contractility is associated with elevated peroxynitrite generation. In addition, we hypothesized that strenuous contractility of the diaphragm increases peroxynitrite formation. In vitro force-frequency relationship, isotonic fatigability, and nitrotyrosine levels were assessed under hypoxic (Po 2 ∼6.5 kPa) and hyperoxic (Po 2 ∼88.2 kPa) control conditions and also in the presence of authentic peroxynitrite (60 min), ebselen (60 min), and the nitric oxide synthase inhibitor N G -monomethyl-l-arginine acetate (l-NMMA) (90 min). A hypoxia-induced downward shift of the force-frequency relationship was associated with elevated nitrotyrosine level in the diaphragm. During hypoxia, both ebselen and l-NMMA decreased nitrotyrosine levels but did not affect force generation. Strenuous contractions impaired force generation but did not affect nitrotyrosine levels in the diaphragm during hypoxia. But under hyperoxic conditions, fatiguing contractions were associated with elevated diaphragm nitrotyrosine levels. Under hyperoxic conditions exogenous peroxynitrite impaired force generation and increased nitrotyrosine level. These studies show that hypoxia-induced impairment in diaphragm contractility is associated with increased diaphragm protein nitration, but no causal relationship was found between diaphragm nitrotyrosine formation and in vitro force generation.
    Type of Medium: Online Resource
    ISSN: 1040-0605 , 1522-1504
    Language: English
    Publisher: American Physiological Society
    Publication Date: 2005
    detail.hit.zdb_id: 1477300-4
    SSG: 12
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  • 3
    Online Resource
    Online Resource
    American Physiological Society ; 2003
    In:  Journal of Applied Physiology Vol. 94, No. 2 ( 2003-02-01), p. 612-620
    In: Journal of Applied Physiology, American Physiological Society, Vol. 94, No. 2 ( 2003-02-01), p. 612-620
    Abstract: Nitric oxide (NO) is essential for optimal myofilament function of the rat diaphragm in vitro during active shortening. Little is known about the role of NO in muscle contraction under hypoxic conditions. Hypoxia might increase the NO synthase (NOS) activity within the rat diaphragm. We hypothesized that NO plays a protective role in isotonic contractile and fatigue properties during hypoxia in vitro. The effects of the NOS inhibitor N G -monomethyl-l-arginine (l-NMMA), the NO scavenger hemoglobin, and the NO donor spermine NONOate on shortening velocity, power generation, and isotonic fatigability during hypoxia were evaluated (Po 2 ∼ 7 kPa). l-NMMA and hemoglobin slowed the shortening velocity, depressed power generation, and increased isotonic fatigability during hypoxia. The effects ofl-NMMA were prevented by coadministration with the NOS substrate l-arginine. Spermine NONOate did not alter isotonic contractile and fatigue properties during hypoxia. These results indicate that endogenous NO is needed for optimal muscle contraction of the rat diaphragm in vitro during hypoxia.
    Type of Medium: Online Resource
    ISSN: 8750-7587 , 1522-1601
    RVK:
    RVK:
    Language: English
    Publisher: American Physiological Society
    Publication Date: 2003
    detail.hit.zdb_id: 1404365-8
    SSG: 12
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  • 4
    In: International Journal of Cardiology, Elsevier BV, Vol. 128, No. 3 ( 2008-08), p. 326-335
    Type of Medium: Online Resource
    ISSN: 0167-5273
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2008
    detail.hit.zdb_id: 1500478-8
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  • 5
    In: Muscle & Nerve, Wiley, Vol. 33, No. 1 ( 2006-01), p. 104-112
    Abstract: Hypoxia impairs neuromuscular transmission in the rat diaphragm. In previous studies, we have shown that nitric oxide (NO) plays a role in force modulation of the diaphragm under hypoxic conditions. The role of NO, a neurotransmitter, on neurotransmission in skeletal muscle under hypoxic conditions is unknown. The effects of the NO synthase (NOS) inhibitor nomega‐nitro‐ L ‐arginine ( L ‐NNA, 1 mM) and the NO donor spermine NONOate (Sp‐NO, 1 mM) were evaluated on neurotransmission failure during nonfatiguing and fatiguing contractions of the rat diaphragm under hypoxic (P O 2 ∼ 5.8 kPa) and hyperoxic conditions (P O 2 ∼ 64.0 kPa). Hypoxia impaired force generated by both muscle stimulation at 40 H Z (P 40 M) and by nerve stimulation at 40 H Z (P 40 N). The effect of hypoxia in the latter was more pronounced. L ‐NNA increased P 40 N whereas Sp‐NO decreased P 40 N during hypoxia. In contrast, neither L ‐NNA nor Sp‐NO affected P 40 N during hyperoxia. L ‐NNA only slightly reduced neurotransmission failure during fatiguing contractions under hyperoxic conditions. Consequently, neurotransmission failure assessed by comparing force loss during repetitive nerve simulation and superimposed direct muscle stimulation was more pronounced in hypoxia, which was alleviated by L ‐NNA and aggravated by Sp‐NO. These data provide insight in the underlying mechanisms of hypoxia‐induced neurotransmission failure. This is important as respiratory muscle failure may result from hypoxia in vivo. Muscle Nerve, 2005
    Type of Medium: Online Resource
    ISSN: 0148-639X , 1097-4598
    URL: Issue
    RVK:
    Language: English
    Publisher: Wiley
    Publication Date: 2006
    detail.hit.zdb_id: 1476641-3
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  • 6
    In: The Journal of Wildlife Management, Wiley, Vol. 81, No. 6 ( 2017-08), p. 1117-1124
    Abstract: We evaluated how proximity to roads and wind turbines affects mesocarnivore visitation with desert tortoises and their burrows at a wind energy facility. Our results suggest that anthropogenic infrastructure associated with wind energy developments might influence the general behavior of predators and their prey.
    Type of Medium: Online Resource
    ISSN: 0022-541X , 1937-2817
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2017
    detail.hit.zdb_id: 2066663-9
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    SSG: 23
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  • 7
    Online Resource
    Online Resource
    Informa UK Limited ; 2006
    In:  International Journal of COPD Vol. 1, No. 1 ( 2006-01), p. 83-89
    In: International Journal of COPD, Informa UK Limited, Vol. 1, No. 1 ( 2006-01), p. 83-89
    Type of Medium: Online Resource
    ISSN: 1176-9106
    URL: Issue
    Language: English
    Publisher: Informa UK Limited
    Publication Date: 2006
    detail.hit.zdb_id: 2212419-6
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  • 8
    In: Wildlife Research, CSIRO Publishing, Vol. 49, No. 3 ( 2021-12-14), p. 283-294
    Abstract: Abstract Context Camera trapping is increasingly used to collect information on wildlife occurrence and behaviour remotely. Not only does the technique provide insights into habitat use by species of interest, it also gathers information on non-target species. Aims We implemented ground-based camera trapping to investigate the behaviours of ground-dwelling birds, a technique that has largely been unutilised for studying birds, especially in wind-energy facilities. Methods We used camera traps to monitor activities of Agassiz’s desert tortoises (Gopherus agassizii) at their self-constructed burrows in a wind-energy facility near Palm Springs, California, USA. While doing so, we collected data on numerous burrow commensals, including birds. Key results Monitoring from late spring to mid-autumn in one year showed regular use of tortoise burrows and the immediate area by 12 species of birds, especially passerines. The most abundant species, as indicated by the number of photographs, but not necessarily individuals, was the rock wren (Salpinctes obsoletus), with a total of 1499 events. Birds appeared to use the interior or proximate vicinity of burrows for gathering nesting material, displaying, feeding, dust bathing and other activities. Of the bird species observed, 10 are known to be occasional casualties of turbine-blade strikes. The minimum known-age of a burrow had a positive relationship with bird counts. Conclusions Using camera traps focused at ground level can be a useful tool in avian conservation efforts because it is an effective technique for measuring bird presence, activity and behaviour in altered habitats such as wind farms, especially for those species that are low flyers or ground dwellers. Implications Acquiring data over the long term by using ground-based monitoring with camera traps could add to our understanding of avian behaviour and habitat use in relation to wind-energy infrastructure and operations, and help determine the vulnerability of avifauna that utilise the area.
    Type of Medium: Online Resource
    ISSN: 1035-3712 , 1448-5494
    Language: English
    Publisher: CSIRO Publishing
    Publication Date: 2021
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    SSG: 23
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