Abstract In the late 19th century, a number of investigators were working on perfecting isolated heart model, but it was Oscar Langendorff who, in 1895, pioneered the isolated perfused mammalian ...heart. Since that time, the Langendorff preparation has evolved and provided a wealth of data underpinning our understanding of the fundamental physiology of the heart: its contractile function, coronary blood flow regulation and cardiac metabolism. In more recent times, the procedure has been used to probe pathophysiology of ischaemia/reperfusion and disease states, and with the dawn of molecular biology and genetic manipulation, the Langendorff perfused heart has remained a stalwart tool in the study of the impact upon the physiology of the heart by pharmacological inhibitors and targeted deletion or up-regulation of genes and their impact upon intracellular signalling and adaption to clinically relevant stressful stimuli. We present here the basic structure of the Langendorff system and the fundamental experimental rules which warrant a viable heart preparation. In addition, we discuss the use of the isolated retrograde perfused heart in the model of ischaemia-reperfusion injury ex-vivo, and its applicability to other areas of study. The Langendorff perfusion apparatus is highly adaptable and this is reflected not only in the procedure's longevity but also in the number of different applications to which it has been turned.
Xanthan gum (XG) is a widely applied natural polysaccharide in food industry as thickening agent. Nowadays, one of the major problems is that some food products are found to be contaminated by ...pathogenic bacteria such as Escherichia coli and Staphylococcus aureus reducing so, their shelf life. This research aims to demonstrate the antibacterial activity of some biodegradable formulation XG‐lignin hydrogel films and their potential application as carriers for controlled release of flavoring compounds. The XG‐lignin films containing an aspen wood lignin type showed a high antibacterial activity against Salmonella Typhymurium ATCC 14028, E. coli ATCC 25922 and Listeria monocytogenes ATCC 25922 bacteria compared with those containing softwood lignin, or lignin from annual plants. Surface morphology indicated a homogeneous distribution of both components within the hydrogel network and the generation of a porous structure after swelling and lyophilization. Additionally, near infrared chemical imaging technique was used as nondestructive method to observe the spatial distribution of the polymeric components and vanillin into the hydrogel films as well as its release profile. The vanillin release rate dependence on the lignin type was also evidenced, a retarded release of vanillin being observed. These results give an important insight into the use of XG, lignin, and vanillin for the development of new edible films for active packaging materials.
Mutations in PTEN inducible kinase-1 (PINK1) induce mitochondrial dysfunction in dopaminergic neurons resulting in an inherited form of Parkinson's disease. Although PINK1 is present in the heart its ...exact role there is unclear. We hypothesized that PINK1 protects the heart against acute ischemia reperfusion injury (IRI) by preventing mitochondrial dysfunction.
Over-expressing PINK1 in HL-1 cardiac cells reduced cell death following simulated IRI (29.2±5.2% PINK1 versus 49.0±2.4% control; N = 320 cells/group P<0.05), and delayed the onset of mitochondrial permeability transition pore (MPTP) opening (by 1.3 fold; P<0.05). Hearts excised from PINK1+/+, PINK1+/- and PINK1-/- mice were subjected to 35 minutes regional ischemia followed by 30 minutes reperfusion. Interestingly, myocardial infarct size was increased in PINK1-/- hearts compared to PINK1+/+ hearts with an intermediate infarct size in PINK1+/- hearts (25.1±2.0% PINK1+/+, 38.9±3.4% PINK1+/- versus 51.5±4.3% PINK1-/- hearts; N>5 animals/group; P<0.05). Cardiomyocytes isolated from PINK1-/- hearts had a lower resting mitochondrial membrane potential, had inhibited mitochondrial respiration, generated more oxidative stress during simulated IRI, and underwent rigor contracture more rapidly in response to an uncoupler when compared to PINK1+/+ cells suggesting mitochondrial dysfunction in hearts deficient in PINK1.
We show that the loss of PINK1 increases the heart's vulnerability to ischemia-reperfusion injury. This may be due, in part, to increased mitochondrial dysfunction. These findings implicate PINK1 as a novel target for cardioprotection.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Glucagon-like Peptide 1 Can Directly Protect the Heart Against Ischemia/Reperfusion Injury
Amal K. Bose 1 ,
Mihaela M. Mocanu 1 ,
Richard D. Carr 2 ,
Christian L. Brand 2 and
Derek M. Yellon 1
1 ...Hatter Institute and Centre for Cardiology, University College London Hospital and Medical School, London, U.K
2 NovoNordisk, Bagsværd, Denmark
Address correspondence and reprint requests to Professor Derek M. Yellon, The Hatter Institute for Cardiovascular Studies,
University College London Hospital and Medical School, Grafton Way, London WC1E, U.K. E-mail: d.yellon{at}ucl.ac.uk
Abstract
Glucagon-like peptide 1 (GLP-1), a gut incretin hormone that stimulates insulin secretion, also activates antiapoptotic signaling
pathways such as phosphoinositide 3-kinase and mitogen-activated protein kinase in pancreatic and insulinoma cells. Since
these kinases have been shown to protect against myocardial injury, we hypothesized that GLP-1 could directly protect the
heart against such injury via these prosurvival signaling pathways. Both isolated perfused rat heart and whole animal models
of ischemia/reperfusion were used, with infarct size measured as the end point of injury. In both studies, GLP-1 added before
ischemia demonstrated a significant reduction in infarction compared with the valine pyrrolidide (an inhibitor of its breakdown)
or saline groups. This protection was abolished in the in vitro hearts by the GLP-1 receptor antagonist exendin (9-39), the
cAMP inhibitor Rp-cAMP, the PI3kinase inhibitor LY294002, and the p42/44 mitogen-activated protein kinase inhibitor UO126.
Western blot analysis demonstrated the phosphorylation of the proapoptotic peptide BAD in the GLP-1–treated groups. We show
for the first time that GLP-1 protects against myocardial infarction in the isolated and intact rat heart. This protection
appears to involve activating multiple prosurvival kinases. This finding may represent a new therapeutic potential for this
class of drug currently undergoing clinical trials in the treatment of type 2 diabetes.
DPPIV, dipeptidyl peptidase-IV
GLP-1, glucagon-like peptide 1
PI3K, phosphoinositide 3-kinase
VP, valine pyrrolidide
Footnotes
D.M.Y. has received grant/research support from NovoNordisk, Denmark.
Accepted September 10, 2004.
Received July 6, 2004.
DIABETES
Brief intermittent episodes of ischemia and reperfusion, at the onset of reperfusion after a prolonged period of ischemia, confer cardioprotection, a phenomenon termed “ischemic postconditioning” ...(Postcond). We hypothesized that this phenomenon may just represent a modified form of reperfusion that activates the reperfusion injury salvage kinase (RISK) pathway. Isolated perfused rat hearts were subjected to(a) 35 minutes of ischemia and 120 minutes of reperfusion, and infarct size was determined by tetrazolium staining; or (b) 35 minutes of ischemia and 7 minutes of reperfusion, and the phosphorylation states of Akt, endothelial NO synthase (eNOS), and p70S6K were determined. Postcond reduced infarct size from 51.2±3.4% to 31.5±4.1% (P<0.01), an effect comparable with ischemic preconditioning (IPC; 27.5±2.3%; P<0.01). Of interest, the combined protective effects of IPC and Postcond were not additive (30.1±4.8% with IPC+Postcond; P=NS). Inhibiting phosphatidylinositol 3-kinase (PI3K) at reperfusion using LY or Wortmannin (Wort) during the first 15 minutes of reperfusion completely abolished Postcond-induced protection (31.5±4.1% with Postcond versus 51.7±4.5% with Postcond+LY, P<0.01; 56.2±10.1% with Postcond+ Wort; P<0.01), suggesting that Postcond protects the heart by activating PI3K–Akt. Western blot analysis demonstrated that Postcond induced a significant increase in phosphorylation of Akt, eNOS, and p70S6K in an LY- and Wort-sensitive manner. In conclusion, we show for the first time that ischemic Postcond protects the myocardium by activating the prosurvival kinases PI3K–Akt, eNOS, and p70S6K in accordance with the RISK pathway.
The Hatter Institute, University College London Hospital, London, United Kingdom
Submitted 19 April 2004
; accepted in final form 26 August 2004
Pharmacological activation of the prosurvival kinases ...Akt and ERK-1/2 at reperfusion, after a period of lethal ischemia, protects the heart against ischemia-reperfusion injury. We hypothesized that ischemic preconditioning (IPC) protects the heart by phosphorylating the prosurvival kinases Akt and ERK-1/2 at reperfusion. In isolated perfused Sprague-Dawley rat hearts subjected to 35 min of lethal ischemia, the phosphorylation states of Akt, ERK-1/2, and p70 S6 kinase (p70S6K) were determined after 15 min of reperfusion, and infarct size was measured after 120 min of reperfusion. IPC induced a biphasic response in Akt and ERK-1/2 phosphorylation during the preconditioning and reperfusion phases after the period of lethal ischemia. IPC induced a fourfold increase in Akt, ERK-1/2, and p70S6K phosphorylation at reperfusion and reduced the infarct risk-to-volume ratio (56.9 ± 5.7 and 20.9 ± 3.6% for control and IPC, respectively, P < 0.01). Inhibiting the IPC-induced phosphorylation of Akt, ERK-1/2, and p70S6K at reperfusion with the phosphatidylinositol 3-kinase (PI3K) inhibitor LY-294002 or the MEK-1/2 inhibitor PD-98059 abrogated IPC-induced protection (46.3 ± 5.8, 49.2 ± 4.0, and 20.9 ± 3.6% for IPC + LY-294002, IPC + PD-98059, and IPC, respectively, P < 0.01), demonstrating that the phosphorylation of these kinases at reperfusion is required for IPC-induced protection. In conclusion, we demonstrate that the reperfusion phase following sustained ischemia plays an essential role in mediating IPC-induced protection. Specifically, we demonstrate that IPC protects the heart by phosphorylating the prosurvival kinases Akt and ERK-1/2 at reperfusion.
mitogen-activated protein kinases; phosphatidylinositol 3-kinase-Akt; myocardial infarction; reperfusion injury
Address for reprint requests and other correspondence: D. M. Yellon, The Hatter Institute, Univ. College London Hospital, Grafton Way, London WC1E 6DB, UK (E-mail: hatter-institute{at}ucl.ac.uk )
Myocardial ischaemia/reperfusion injury leading to myocardial infarction is one of the most frequent causes of debilitation and death in man. Considerable research has been undertaken to investigate ...the possibility of reducing myocardial infarction and increasing cell survival by activating certain endogenous prosurvival signaling pathways. Thus, it has been established that the activation of the PI3K (Phosphoinositide‐3 kinase)/Akt (Protein kinase B, PKB) signaling pathway is essential for protection against ischaemia/reperfusion injury. This pathway has been shown to be activated by mechanical procedures (e.g. pre and post conditioning) as well as by a number of pharmacological agents. Although the activation of this prosurvival signaling pathway induces the phosphorylation of a large number of substrates implicated in increased cell survival, when activated over a prolonged period this pathway can have detrimental consequences by facilitating unwanted growth and malignancies. Importantly PTEN (phosphatase and tensin homolog deleted on chromosome ten), is the main phosphatase which negatively regulates the PI3K/Akt pathway. In this review we discuss: a) the significance and the limitations of inhibiting PTEN in myocardial ischaemia/reperfusion injury; b) PTEN and its relationship to ischaemic preconditioning, c) the role of PTEN in the development of tolerance to chronic administration of drugs known to limit infarction by activating PI3K/Akt pathway when given acutely, and d) the possible role of PTEN in the ischaemic/reperfused diabetic heart. The experimental evidence discussed in this review illustrates the importance of PTEN inhibition in the protection of the heart against ischaemia/reperfusion injury.
British Journal of Pharmacology (2007) 150, 833–838. doi:10.1038/sj.bjp.0707155
Wide-field Optical Imaging of Intrinsic Signals (OI-IS; Grinvald et al., 1986) is a method for imaging functional brain hemodynamic responses, mainly used to image activity from the surface of the ...cerebral cortex. It localizes small functional modules - such as cortical columns - with great spatial resolution and spatial specificity relative to the site of increases in neuronal activity. OI-IS is capable of imaging responses either through an intact or thinned skull or following a craniotomy. Therefore, it is minimally invasive, which makes it ideal for survival experiments. Here we describe OI-IS-based methods for guiding microinjections of optogenetics viral vectors in proximity to small functional modules (S1 barrels) of the cerebral cortex and for guiding the insertion of electrodes for electrophysiological recording into such modules. We validate our proposed methods by tissue processing of the cerebral barrel field area, revealing the track of the electrode in a predetermined barrel. In addition, we demonstrate the use of optical imaging to visualize the spatial extent of the optogenetics photostimulation, making it possible to estimate one of the two variables that conjointly determine which region of the brain is stimulated. Lastly, we demonstrate the use of OI-IS at high-magnification for imaging the upper recording contacts of a laminar probe, making it possible to estimate the insertion depth of all contacts relative to the surface of the cortex. These methods support the precise positioning of microinjections and recording electrodes, thus overcoming the variability in the spatial position of fine-scale functional modules.
Necrostatin (Nec-1) protects against ischemia-reperfusion (IR) injury in both brain and heart. We have previously reported in this journal that necrostatin can delay opening of the mitochondrial ...permeability transition pore (MPTP) in isolated cardiomyocytes.
The aim of the present study was to investigate in more detail the role played by the MPTP in necrostatin-mediated cardioprotection employing mice lacking a key component of the MPTP, namely cyclophilin-D.
Anaesthetized wild type (WT) and cyclophilin-D knockout (Cyp-D-/-) mice underwent an open-chest procedure involving 30 min of myocardial ischemia and 2 h of reperfusion, with subsequent infarct size assessed by triphenyltetrazolium staining. Nec-1, given at reperfusion, significantly limited infarct size in WT mice (17.7 +/- 3% vs. 54.3 +/- 3%, P < 0.05) but not in Cyp-D-/- mice (28.3 +/- 7% vs. 30.8 +/- 6%, P > 0.05).
The data obtained in Cyp-D-/- mice provide further evidence that Nec-1 protects against myocardial IR injury by modulating MPTP opening at reperfusion.
Dibaryons and where to find them Bashkanov, M; Watts, D P; Clash, G ...
Journal of physics. G, Nuclear and particle physics,
04/2024, Letnik:
51, Številka:
4
Journal Article
Recenzirano
Odprti dostop
Abstract In recent years, there has been tremendous progress in the investigation of bound systems of quarks with multiplicities beyond the more usual two- and three-quark systems. Experimental and ...theoretical progress has been made in the four-, five- and even six-quark sectors. In this paper, we review the possible lightest six-quark states using a simple ansatz based on SU(3) symmetry and evaluate the most promising decay branches. The work will be useful to help focus future experimental searches in this six-quark sector.
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