Myocardial cell death in fibrillating and dilated human right atria
Christine Aimé-Sempé, PhD*,
Thierry Folliguet, MD ,
Catherine Rücker-Martin, PhD ,
Maryla Krajewska, MD||,
Stanislaw Krajewski, MD||,
Michèle Heimburger, PhD ,
Michel Aubier, MD, PhD*,
Jean-Jacques Mercadier, MD, PhD,
John C. Reed, MD, PhD|| and
Stephane N. Hatem, MD, PhD
* INSERM U408, Faculté de Médecine, Xavier Bichat, Paris, France
INSERM U460, Faculté de Médecine, Xavier Bichat, Paris, France
Université de Paris XI-CNRS ERS 566, Hôpital Marie Lannelongue, Le Plessis Robinson, France
the Department de Chirurgie Cardiaque, Institut Mutualiste Montsouris, Paris, France
|| the Burnham Institute, La Jolla, California, USA
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Figure 1 Tissue sections from control (A, C, E) and dilated and fibrillating atria (B, D, F). Collagen and elastic fibers were stained with Masson’s trichrome (A, B), orcein (C, D) and glycogen granules with PAS (E, F), respectively (arrow), and nuclei were counterstained with hematoxylin. A to E, bar = 40 µm; E and F, bar = 20 µm.
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Figure 2 Immunostaining of atrial sections with antibodies against sarcomeric  -actinin observed by means of confocal microscopy showing disruption of the myofibrillar apparatus in myocytes from diseased (B) but not from control (A) atria. Insets show higher magnifications of the myofibrillar areas indicated by arrows in A and B, respectively. Bar = 5 µm.
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Figure 3 Percentage of myocytes with myolysis in tissue sections from fibrillating atria (n = 11 patients), from heart in sinus rhythm with a normal (EF > 45%, n = 9 patients) or a low left ventricular function (EF < 45%, n = 8 patients). **p < 0.001.
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Figure 4 Staining of nuclei with DAPI. (A) Section from control atria. (B) Section from a fibrillating atria with number of myocytes with myolysis showing large nuclei with a redistribution of their heterochromatin. Examples of fragmented (C, arrow) and condensated (D, arrow) nuclei from two sections of diseased atria. Bar = 20 µm.
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Figure 5 Staining of tissue sections with the TUNEL. (A) None of the nuclei of normally structured myocytes from control tissue section was stained with TUNEL. (B) A high percentage of the nuclei of myocytes with myolysis showed a weak dUTP staining. (C and D) Examples of strong dUTP staining of nuclei showing morphological alterations. Bar = 20 µm.
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Figure 6 Electrophoresis patterns of DNA extracted from two control atria (lanes 1, 2) one dilated atria in sinus rhythm (lane 3) and two fibrillating atria (lanes 4, 5). No typical DNA ladders were observed in all the samples studied.
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Figure 7 Immunohistochemical detection of the protease CASP-3 in atrial myocardium. (A) Control adult atrium shows weak, diffuse, fine-granular CASP-3 immunoreactions in most myocytes. Note, that only singular fibers showed more intense CASP-3 immunoreactivity (arrow). (B to D) A number of myocytes from dilated and fibrillating atria heavily loaded with coarse-grained CASP-3 deposits (B, arrows). Note that nuclei of the most affected cells demonstrate hyperchromasia (C and D). Bar = 20 µm.
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Figure 8 Expression of CASP-3, BCL-2 and BAX protein. (A) Whereas p32 isoform of CASP-3 was detected in all patients, the p17 isoform was detected only in patients with AF (lanes 2 and 5) and in some patients with LLVEF (lanes 3 and 4). (B) A lower expression of BCL-2 was observed in patients with AF (lanes 2 and 5) and with LLVEF (lanes 3, 4 and 7) compared with control patients (lanes 1 and 6) while BAX expression was unchanged. In all samples analyzed, a 23-kDa band was detected with antibody directed against BCL-2, the expression of which was enhanced in patients with AF (lanes 2 and 5) or with LLVEF (lanes 3, 4 and 7) compared with control patients (lanes 1 and 6). Tubulin was used as a control of equal loading and, except for patient in lane 2, soluble tubulin was the predominant form.
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