Search results for "Rabbits"
showing 10 items of 501 documents
Experimental Study of the Effects of EIPA, Losartan, and BQ-123 on Electrophysiological Changes Induced by Myocardial Stretch
2015
[ES] Introducción y objetivos Se han implicado diversos mecanismos en la respuesta mecánica al estiramiento miocárdico, que incluyen la activación del intercambiador Na+/H+ por acciones autocrinas y paracrinas. Se estudia la participación de estos mecanismos en las respuestas electrofisiológicas al estiramiento agudo miocárdico mediante el análisis de los cambios inducidos con fármacos. Métodos Se analizan las modificaciones de la fibrilación ventricular inducidas por el estiramiento agudo miocárdico en corazones de conejo aislados y perfundidos utilizando electrodos múltiples epicárdicos y técnicas cartográficas. Se estudian 4 series: control (n = 9); durante la perfusión del antagonista d…
Mechanisms underlying diabetes enhancement of endothelin-1-induced contraction in rabbit basilar artery
2004
The influence of alloxan-induced diabetes on the reactivity of rabbit basilar artery to endothelin-1 was examined. Endothelin-1 induced concentration-dependent contraction of basilar arteries that was higher in diabetic than in control rabbits. Endothelium removal produced a higher enhancement of the endothelin-1-induced contraction in control than in diabetic rabbits. N(G)-nitro-L-arginine (L-NOArg) enhanced the maximal contraction induced by endothelin-1 in control rabbits and potentiated this response in diabetic rabbits. Endothelin ETA receptor antagonist, cyclo(D-Asp-Pro-D-Val-Leu-D-Trp) (BQ-123), inhibited endothelin-1-induced contraction in both rabbit groups. Endothelin ETB receptor…
Three-dimensional cardiac computational modelling: methods, features and applications
2015
[EN] The combination of computational models and biophysical simulations can help to interpret an array of experimental data and contribute to the understanding, diagnosis and treatment of complex diseases such as cardiac arrhythmias. For this reason, three-dimensional (3D) cardiac computational modelling is currently a rising field of research. The advance of medical imaging technology over the last decades has allowed the evolution from generic to patient-specific 3D cardiac models that faithfully represent the anatomy and different cardiac features of a given alive subject. Here we analyse sixty representative 3D cardiac computational models developed and published during the last fifty …
New epicardial mapping electrode with warming/cooling function for experimental electrophysiology studies
2010
Cardiac electrical activity is influenced by temperature. In experimental models, the induction of hypothermia and/or hyperthermia has been used for the study of mechanisms of cardiac arrhythmia. A system that allows for localized, controlled induction, besides simultaneously recording electrical activity in the same induced area, needs to be developed ad hoc. This article describes the construction and application of a new system capable of locally modifying the epicardial temperature of isolated hearts and of carrying out cardiac mapping with sufficient spatial resolution. The system is based on a thermoelectric refrigerator and an array of 128 stainless steel unipolar electrodes in encap…
Phobalysin, a Small β-Pore-Forming Toxin of Photobacterium damselae subsp. damselae
2015
ABSTRACT Photobacterium damselae subsp. damselae , an important pathogen of marine animals, may also cause septicemia or hyperaggressive necrotizing fasciitis in humans. We previously showed that hemolysin genes are critical for virulence of this organism in mice and fish. In the present study, we characterized the hlyA gene product, a putative small β-pore-forming toxin, and termed it phobalysin P (PhlyP), for “photobacterial lysin encoded on a plasmid.” PhlyP formed stable oligomers and small membrane pores, causing efflux of K + , with no significant leakage of lactate dehydrogenase but entry of vital dyes. The latter feature distinguished PhlyP from the related Vibrio cholerae cytolysin…
Phenoloxidase-dependent cytotoxic mechanism in ascidian (Styela plicata) hemocytes active against erythrocytes and K562 tumor cells.
1997
The cytotoxic activity against rabbit erythrocytes (RE) and human K562 tumor cells by Styela plicata hemocytes was significantly related to the phenoloxidase (PO) which converts phenols to quinone and initiates the melanogenic pathway. The effector hemocyte population, separated in a Percoll density gradient band, enriched in a granulocyte type named "morula cells", was examined with RE in a hemocyte cytotoxic assay and plaque forming cell assay. Inhibition experiments with the copper chelating agents 1-phenyl-2-thiourea and tropolone, the substrate analogue sodium benzoate and sodium ascorbate support the notion that hemocyte cytotoxic activity is a PO-dependent mechanism. Treatments of he…
Importance of Factors H and I for the Adherence of C3b-Coated Erythrocytes to Cells
1983
Abstract The role of cell membrane-associated human factor H for the binding of cell-bound Cab to complement receptor-carrying (CR + ) cells was investigated. Pretreatment of CR + cells with antibodies to factor H inhibited the adherence of Cab-coated red cells to human tonsil lymphocytes (TL) and peripheral blood monocytes (Mo). The Cab receptor reactivity of human polymorphonuclear leucocytes (PMN) was not influenced and the one of Raji lymphoblastoid cells only slightly influenced; iC3b and Cad receptor reactivity was in no case affected. When diisopropylfluorophosphate (DFP) in a concentration of 0.1 mM was present during pretreatment of the CR + cells with anti H, the antibodies gained…
Transmembrane beta-barrel of staphylococcal alpha-toxin forms in sensitive but not in resistant cells.
1997
Staphylococcal α-toxin is a 293-residue, single-chain polypeptide that spontaneously assembles into a heptameric pore in target cell membranes. To identify the pore-forming domain, substitution mutants have been produced in which single cysteine residues were introduced throughout the toxin molecule. By attaching the environmentally sensitive dye acrylodan to the sulfhydryl groups, the environment of individual amino acid side chains could be probed. In liposomes, a single 23-amino acid sequence (residues 118–140) was found to move from a polar to a nonpolar environment, indicating that this sequence forms the walls of the pore. However, periodicity in side chain environmental polarity coul…
Evidence that clustered phosphocholine head groups serve as sites for binding and assembly of an oligomeric protein pore.
2006
High susceptibility of rabbit erythrocytes toward the pore-forming action of staphylococcal alpha-toxin correlates with the presence of saturable, high affinity binding sites. All efforts to identify a protein or glycolipid receptor have failed, and the fact that liposomes composed solely of phosphatidylcholine are efficiently permeabilized adds to the enigma. A novel concept is advanced here to explain the puzzle. We propose that low affinity binding moieties can assume the role of high affinity binding sites due to their spatial arrangement in the membrane. Evidence is presented that phosphocholine head groups of sphingomyelin, clustered in sphingomyelin-cholesterol microdomains, serve th…
In vivo survival rate of rabbit morulae after vitrification in a medium without serum protein.
2000
The in vivo survival rate of rabbit morulae after vitrification in a mixture of dimethyl sulphoxide and ethylene glycol solution without protein supplement (WPS) was compared with two types of protein supplements: rabbit serum (RS) and bovine serum albumin (BSA). Significant dif- ferences were observed in the percentage of transferable embryos (undamaged embryos after devit- rification, 80.4 % versus 93.2 and 92.1 %, WPS, BSA and RS, respectively, P < 0.05) and live born rate (40.9 % versus 56.1 %, WPS and BSA, respectively, P < 0.05). Non-significant differences were, however, observed in the percentages of implanted embryos at 12 days post-ovulation induc- tion (56.7, 69.7 and 68.6 %), po…