GLORIA

GEOMAR Library Ocean Research Information Access

feed icon rss

Ihre E-Mail wurde erfolgreich gesendet. Bitte prüfen Sie Ihren Maileingang.

Leider ist ein Fehler beim E-Mail-Versand aufgetreten. Bitte versuchen Sie es erneut.

Vorgang fortführen?

Exportieren
  • 1
    Digitale Medien
    Digitale Medien
    Boston, MA, USA : Blackwell Science Inc
    Restoration ecology 10 (2002), S. 0 
    ISSN: 1526-100X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: The effects of intensive recreation impacts and restoration amendments on soil parameters were assessed at four campsites in the Eagle Cap Wilderness, northeastern Oregon. Sites (2,215- to 2,300-m elevation) are characterized by shallow granitic soils, an Abies lasiocarpa/Pinus albicaulis overstory, and a Vaccinium scoparium understory. In fall 1995, plots were established at four campsites on three subalpine lakes in which soils were scarified, compost amended, and planted to native species. In summer 1998, we sampled surface soils (0–15 cm) on undisturbed sites (between and under vegetation) and unamended and compost-amended campsite soils. Samples were analyzed for total organic C, total N, potentially mineralizable N (PMN), NH4, soil moisture, microbial biomass, basal 5-day respiration rates, and microbial community carbon utilization profiles. Unamended campsite soils had significantly lower levels of PMN, microbial biomass, basal respiration, and number of substrates metabolized in carbon utilization profiles. Compost addition elevated all these impacted parameters on campsite soils, although the increase in basal respiration rate was neither statistically significant nor sufficient to approach rates found underneath vegetation on undisturbed soils. Only the number of substrates metabolized in the carbon utilization profiles was significantly higher on compost-amended soils than on undisturbed soils. Levels of PMN indicate that campsite soils may lack sufficient N for rapid plant regeneration, whereas amended and undisturbed soils contained adequate quantities of available N. This work suggests that compost amendments can ameliorate impacts to soil chemistry and microbial populations caused by camping, without exceeding the N fertility found on undisturbed soils.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 2
    Digitale Medien
    Digitale Medien
    Malden, USA : Blackwell Science Inc
    Wound repair and regeneration 11 (2003), S. 0 
    ISSN: 1524-475X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 3
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Science Inc
    Journal of cardiovascular electrophysiology 12 (2001), S. 0 
    ISSN: 1540-8167
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Hyperthermic Myocardial Injury. Introduction: We hypothesized that intracellular calcium overload may play an important role in heat-induced myocardial injury. This postulate was investigated using a model of isolated guinea pig papillary muscle in which resting tension was measured as an indirect indicator of cytosolic free-calcium concentration and the fluorescence changes of Fluo-3 AM dye was measured as a direct indicator of cytosolic free-calcium concentration. Methods and Results: Excised guinea pig right ventricular papillary muscles were attached to a force transducer in a high-flow tissue bath and superfused with Tyrode's solution at 37°± 0.5°C. The temperature was rapidly changed to between 38.0° and 56.0°C for 60 seconds and then returned to 37.0°C. Hyperthermia caused a reversible increase in resting tension at temperatures between 45° and 50°C and irreversible contracture at ≥50°C. Rapid cooling contracture experiments and experiments measuring fluorescence of myocytes loaded with 5 μ M Fluo-3 AM dye demonstrated that the hyperthermia-induced rise in resting tension was likely due to an increase in intracellular calcium content. Inhibition of the sarcoplasmic reticulum calcium pump with 20 μ M thapsigargin resulted in irreversible contracture of the papillary muscles at temperatures between 45° and 50°C and significant increases in Fluo-3 fluorescence at 48°C. Blockade of sarcolemmal calcium channels with 0.5 mM cadmium or 40 μ M verapamil did not attenuate the heat-induced increase in resting tension and Fluo-3 fluorescence. Conclusion: Hyperthermia causes an increase in resting tension of cardiac muscle that most likely is mediated by a calcium channel-independent increase in calcium permeability of the sarcolemmal membrane and/or release of stored intracellular calcium.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 4
    Digitale Medien
    Digitale Medien
    350 Main Street , Malden , MA 02148-5018 , USA , and 9600 Garsington Road , Oxford OX4 2DQ , UK . : Blackwell Science Inc
    Journal of cardiovascular electrophysiology 14 (2003), S. 0 
    ISSN: 1540-8167
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Introduction: Heart failure is associated with reduced expression of the major gap junction protein connexin43 (Cx43), which may contribute to arrhythmias and sudden cardiac death in this patient population. Other cardiac connexins may be altered as well. Because connexin45 (Cx45) has been shown to colocalize with Cx43, we determined whether the number, size, or distribution of Cx45 gap junctions is altered in the failing heart. Methods and Results: Cx45 expression levels were measured by immunoblotting and quantitative immunostaining in failing and control human left ventricles. Total Cx45 protein was significantly (P = 0.021) up-regulated 1.8-fold in failing hearts. Cx45 immunohistochemical signal was increased by 80% (P = 0.005) due to a 3.5-fold increase in the number of gap junctions containing Cx45. Cx45 mRNA was not altered in failing hearts, suggesting reduced degradation of Cx45 protein in the failing heart. Cx43 signal, on the other hand, was reduced by 49% in failing hearts. Double-label experiments demonstrated colocalization of Cx45 and Cx43 in the same gap junctions. Conclusion: Cx45 is markedly enhanced in the failing heart. Up-regulation of Cx45 in conjunction with down-regulation of Cx43 could result in abnormal impulse propagation and generation of ventricular arrhythmias, thereby predisposing patients in heart failure to sudden cardiac death. (J Cardiovasc Electrophysiol, Vol. 14, pp. 1205-1212, November 2003)
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 5
    Digitale Medien
    Digitale Medien
    350 Main Street , Malden , MA 02148 , USA , and 9600 Garsington Road , Oxford OX4 2DQ , UK . : Blackwell Science Inc
    Journal of cardiovascular electrophysiology 14 (2003), S. 0 
    ISSN: 1540-8167
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Introduction: The success of radiofrequency energy catheter ablation for the treatment of patients with paroxysmal or chronic atrial fibrillation has been complicated by postablation development of pulmonary vein (PV) stenosis. The acute effect of heat on PV structure has not been well characterized. The aim of this study was to characterize the effects of hyperthermic exposure on PVs and to determine the critical temperature at which PV stenosis would be observed. Methods and Results: The main PVs of acutely explanted canine hearts were identified, isolated, and dissected from the left atria. Measurements of the diameter of 3-mm PV rings were obtained at baseline and after hyperthermic exposure at 60°C, 65°C, 70°C, and 80°C. Mechanical behavior of PVs was studied by examining the stress-strain relationship of each PV specimen after heat exposure at different temperature settings. Twenty-eight PVs samples from 15 dogs (1–3 PVs/dog) were obtained and had a mean circumference of 8.7 ± 2.3 mm at baseline. After heating to 60°C, 65°C, 70°C, and 80°C, the mean PV circumference was 9.2 ± 2.3 mm (P = NS vs baseline), 6.8 ± 2.3 mm (P 〈 0.0001), 4.2 ± 1.5 mm (P 〈 0.0001) , and 4.2 ± 0.8 mm (P 〈 0.0001) , respectively. The stress-strain curves of PV specimens were shifted to the left upon exposure to higher temperatures, indicating loss of compliance of PVs due to heat exposure. Histology showed loss of typical collagen matrix above 60°C. Conclusion: Significant acute heat-induced contraction of PVs at zero-tension state was observed between 60°C and 65°C. This change was associated with collagen denaturation. (J Cardiovasc Electrophysiol, Vol. 14, pp. 250-254, March 2003)
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 6
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Science Inc
    Journal of cardiovascular electrophysiology 13 (2002), S. 0 
    ISSN: 1540-8167
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Spatiotemporal Organization in Atrial Fibrillation. Introduction: Atrial fibrillation (AF) may originate from discrete sites of periodic activity. We studied the effect of structural and electrical remodeling on spatiotemporal organization in acute and persistent AF. Methods and Results: Atrial effective refractory periods (AERPs) were recorded from five different sites at baseline and after pacing in acute AF (n = 8 dogs) and persistent AF (n = 8). Four persistent AF dogs subsequently were cardioverted to sinus rhythm to allow AERP recovery. Periodicity was quantified by calculating power spectra on left atrial electrograms obtained from a 64-electrode basket catheter. Left atrial size was measured by intracardiac echocardiography and structural changes were assessed by electron microscopy. Mean AERPs decreased after pacing in acute (128 ± 16 msec to 108 ± 29 msec, P 〈 0.001) and persistent AF (135 ± 16 msec to 104 ± 24 msec, P 〈 0.0001). AERP recovery was established after 7 days of sinus rhythm. Structural changes were mild in acute AF, severe in persistent AF, and remained severe after AERP recovery. A single dominant frequency was identified in 94% of acute AF bipoles, 57% in persistent AF, and 76% after AERP recovery. Average correlation coefficient was 0.82 among acute AF bipoles, 0.63 in persistent AF, and 0.73 after AERP recovery. Conclusion: Transition from acute to persistent AF is associated with loss of spatiotemporal organization. A single dominant frequency recruits the majority of the left atrium in acute AF. Persistent AF, however, is associated with structural remodeling and dominant frequency dispersion. Recovery of refractoriness only partially restores spatiotemporal organization, indicating a major role for structural remodeling in the maintenance of persistent AF.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 7
    Digitale Medien
    Digitale Medien
    350 Main Street , Malden , MA 02148-5018 , USA and 9600 Garsington Road , Oxford OX4 2DQ , UK . : Blackwell Science Inc
    Pacing and clinical electrophysiology 28 (2005), S. 0 
    ISSN: 1540-8159
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: We present two cases that demonstrate a new technique to cannulate angulated and tortuous coronary sinus branches during left ventricular lead placement for cardiac resynchronization therapy. The technique uses an occlusive pulmonary artery balloon just beyond the takeoff of the coronary sinus branch to assist in the cannulation of the branch.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
Schließen ⊗
Diese Webseite nutzt Cookies und das Analyse-Tool Matomo. Weitere Informationen finden Sie hier...