Endothelial dysfunction of bypass graft: Direct comparison of In Vitro and In Vivo models of ischemia-reperfusion injury

BACKGROUND: Although, ischemia/reperfusion induced vascular dysfunction has been widely described, no comparative study of in vivo- and in vitro-models exist. In this study, we provide a direct comparison between models (A) ischemic storage and in-vitro reoxygenation (B) ischemic storage and in vitro reperfusion (C) ischemic storage and in-vivo reperfusion. METHODS AND RESULTS: Aortic arches from rats were stored for 2 hours in saline. Arches were then (A) in vitro reoxygenated (B) in vitro incubated in hypochlorite for 30 minutes (C) in vivo reperfused after heterotransplantation (2, 24 hours and 7 days reperfusion). Endothelium-dependent and independent vasorelaxations were assessed in organ bath. DNA strand breaks were assessed by TUNEL-method, mRNA expressions (caspase-3, bax, bcl-2, eNOS) by quantitative real-time PCR, proteins by Western blot analysis and the expression of CD-31 by immunochemistry. Endothelium-dependent maximal relaxation was drastically reduced in the in-vivo models compared to ischemic storage and in-vitro reperfusion group, and no difference showed between ischemic storage and control group. CD31-staining showed significantly lower endothelium surface ratio in-vivo, which correlated with TUNEL-positive ratio. Increased mRNA and protein levels of pro- and anti-apoptotic gens indicated a significantly higher damage in the in-vivo models. CONCLUSION: Even short-period of ischemia induces severe endothelial damage (in-vivo reperfusion model). In-vitro models of ischemia-reperfusion injury can be limitedly suited for reliable investigations. Time course of endothelial stunning is also described

Discutindo a educação ambiental no cotidiano escolar: desenvolvimento de projetos na escola formação inicial e continuada de professores

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Sozialwissenschaftliche Forschungsdaten als historische Quellen: Welche Infrastrukturbedarfe hat die zeitgeschichtliche Forschung?

Der Beitrag stellt die Ergebnisse einer Bedarfsanalyse auf dem Feld der Zeitgeschichte vor, die im Rahmen des im Januar 2020 gestarteten DFG-Projektes "Sozialdaten als Quellen der Zeitgeschichte. Erstellung eines Rahmenkonzepts für eine Forschungsdateninfrastruktur in der zeithistorischen Forschung" durchgeführt wurde. Die Zeitgeschichte hat in den letzten zehn Jahren neue Forschungsthemen aufgegriffen, die die Erschließung und Auswertung in der Geschichtswissenschaft bisher selten genutzter sozialwissenschaftlicher Forschungsdaten auf die Tagesordnung der methodischen und konzeptionellen Debatten gesetzt haben. Neben den Beständen audio-visueller Medienarchive gehören dazu beispielsweise amtliche statistische Erhebungen oder Daten der zeitgenössischen sozialwissenschaftlichen Forschung. Der wissenschaftliche Wert dieser qualitativen und quantitativen Daten für die historische Forschung ist unbestritten und geht über die Zeitgeschichte hinaus. Zeithistoriker:innen nutzen Sozialdaten, um zeitgenössische Forschungsergebnisse der Sozialwissenschaften in historischer Perspektive kritisch zu prüfen und neue Fragen an die Daten zu stellen. Auf Basis umfangreicher Recherchen zeigt der Aufsatz, welche Herausforderungen Zeithistoriker:innen bei der Nachnutzung von sozialwissenschaftlich produzierten Daten bewältigen müssen und welche Bedarfe sich für eine zeithistorische Forschungsdateninfrastruktur daraus ergeben

Prolyl-hydroxylase inhibition preserves endothelial cell function in a rat model of vascular ischemia reperfusion injury Running Title: Prolyl-hydroxylase inhibition preserves endothelial function Section: Cardiovascular Text pages: 23 Number of tables: 1

List of non-standard abbreviations: PHD: prolyl-hyroxylase-domain containing enzyme, DMOG: dimethyloxalylglycine, HO-1: heme-oxygenase-1, HIF: hypoxia inducible factor, 2-OG: 2-oxoglutarate, ROS: reactive oxygen species, VSMC: vascular smooth muscle cell, IR: ischemia-reperfusion We investigated endothelium-dependent and -independent vasorelaxations. To simulate IR-injury hypochlorite (NaOCl) was added during warm reperfusion. VSMCs were incubated in NaCl or DMOG solution at 4ºC for 24h after the medium was changed for a supplied standard medium at 37ºC for 6h. Apoptosis was assessed by the TUNEL-method. Gene expression analysis was performed by quantitative real-time PCR. Cold ischemic preservation + NaOCl induced severe endothelial dysfunction, which was significantly improved by DMOG supplementation (maximal relaxation of aortic segments to acetylcholine: control 95±1 vs. NaOCl 44±4 vs. DMOG 68±5%). Number of TUNELpositive cell nuclei was significantly higher in the NaOCl-group and DMOG-treatment significantly decreased apoptosis. Inducible heme-oxygenase 1 mRNA expressions were significantly higher in the DMOG group. Pharmacological modulation of oxygen sensing system by DMOG in an in vitro model of vascular IR effectively preserved endothelial function. Inhibition of PHDs could be therefore a new therapeutic avenue for protecting endothelium and vascular muscle cells against IR-injury

Prolyl-Hydroxylase Inhibition Preserves Endothelial Cell Function in a Rat Model of Vascular Ischemia Reperfusion Injury

ABSTRACT Storage protocols of vascular grafts need further improvement against ischemia-reperfusion (IR) injury. Hypoxia elicits a variety of complex cellular responses by altering the activity of many signaling pathways, such as the oxygen-dependent prolylhyroxylase domain-containing enzyme (PHD). Reduction of PHD activity during hypoxia leads to stabilization and accumulation of hypoxia inducible factor (HIF) 1a. We examined the effects of PHD inhibiton by dimethyloxalylglycine on the vasomotor responses of isolated rat aorta and aortic vascular smooth muscle cells (VSMCs) in a model of cold ischemia/warm reperfusion. Aortic segments underwent 24 hours of cold ischemic preservation in saline or DMOG (dimethyloxalylglycine)-supplemented saline solution. We investigated endothelium-dependent and -independent vasorelaxations. To simulate IR injury, hypochlorite (NaOCl) was added during warm reperfusion. VSMCs were incubated in NaCl or DMOG solution at 4°C for 24 hours after the medium was changed for a supplied standard medium at 37°C for 6 hours. Apoptosis was assessed using the TUNEL method. Gene expression analysis was performed using quantitative real-time polymerase chain reaction. Cold ischemic preservation and NaOCl induced severe endothelial dysfunction, which was significantly improved by DMOG supplementation (maximal relaxation of aortic segments to acetylcholine: control 95% 6 1% versus NaOCl 44% 6 4% versus DMOG 68% 6 5%). Number of TUNEL-positive cell nuclei was significantly higher in the NaOCl group, and DMOG treatment significantly decreased apoptosis. Inducible heme-oxygenase 1 mRNA expressions were significantly higher in the DMOG group. Pharmacological modulation of oxygen sensing system by DMOG in an in vitro model of vascular IR effectively preserved endothelial function. Inhibition of PHDs could therefore be a new therapeutic avenue for protecting endothelium and vascular muscle cells against IR injury

Gene expressions of (A) Bax, (B) Bcl-2, (C) caspase-3 and (D) endothelial nitric oxide synthase (eNOS) in aortic rings.

<p>Controls were given the arbitrary value of 1. Values represent median ± quartiles; *P<.05 versus control; #P<.05 versus ischemic storage; ‡P<.05 versus ischemic storage and in vitro reperfusion; †P<.05 versus ischemic storage and in vivo 2h reperfusion.</p

Groups and treatments.

<p>Groups and treatments.</p