Redistribution of connexin43 in regional acute ischemic myocardium: influence of ischemic preconditioning

2006 ◽  
Vol 291 (2) ◽  
pp. H813-H819 ◽  
Author(s):  
Friedrich Vetterlein ◽  
Christian Mühlfeld ◽  
Cenk Cetegen ◽  
Rolf Volkmann ◽  
Christina Schrader ◽  
...  
Keyword(s):  
Gap Junctions ◽  
Ischemic Preconditioning ◽  
Immunohistochemical Staining ◽  
Cellular Membrane ◽  
Frozen Sections ◽  
Independent Mechanism ◽  
Regional Myocardial Ischemia ◽  
Subsequent Phase ◽  
Free Plasma ◽  
Immunofluorescence Intensity

Connexins are known to play an essential role in the ischemic preconditioning (IP) of the heart; their functional role in this process, however, has not been clearly defined. For this reason, anesthetized rats were subjected to regional myocardial ischemia, with or without IP or reperfusion. In frozen sections of hearts, fluorescence immunohistochemical staining for connexin43 (Cx43) was performed. In contrast to undisturbed zones, tissue that had been subjected to ischemia revealed Cx43 immunostaining not only in the gap junctions but also in a conspicuous pattern in the free cellular membranes of the myocytes. In myocardium that was exposed to IP only, the ratio of immunofluorescence intensity in the free cellular membrane to that in the interior of the cell was 1.22 ± 0.04 (ratio in non-ischemia-exposed area = 1.04 ± 0.01). When 15 or 45 min of permanent ischemia followed IP, the effect became more evident (ratio = 1.31 ± 0.03 and 1.46 ± 0.03, respectively) and proved to be significantly greater than in the corresponding non-IP groups (ratio = 1.16 ± 0.03 and 1.30 ± 0.03, respectively, P < 0.01). Reperfusion led to an overall weakening of fluorescence intensities and a disappearance of the observed IP-specific differences. We conclude that IP initiates a redistribution of Cx43 from its natural position in the gap junctions toward the free plasma membrane, thereby improving the cell's chance of survival during the subsequent phase of prolonged ischemia by an unknown, supposedly gap junction-independent, mechanism.

scholarly journals Microfluidics for rapid cytokeratin immunohistochemical staining in frozen sections

2017 ◽  
Vol 97 (8) ◽  
pp. 983-991 ◽  
Author(s):  
Saska Brajkovic ◽  
Diego G Dupouy ◽  
Laurence de Leval ◽  
Martin AM Gijs
Keyword(s):  
Immunohistochemical Staining ◽  
Frozen Sections

scholarly journals A Rare Primary Tumor of the Thyroid Gland: A New Case of Leiomyoma and Literature Review

2018 ◽  
Vol 12 ◽  
pp. 117955491881353
Author(s):  
Yanling Zhang ◽  
Heng Tang ◽  
Huaiyuan Hu ◽  
Xiang Yong
Keyword(s):  
Thyroid Gland ◽  
Tumor Cells ◽  
Immunohistochemical Staining ◽  
Smooth Muscle Actin ◽  
Frozen Sections ◽  
Ki 67 ◽  
Eosinophilic Cytoplasm ◽  
S 100 ◽  
Painless Mass ◽  
The Right

Primary leiomyomas of the thyroid are very rare. We here report a case of a 53-year-old woman with a painless mass at the right thyroid, revealed by physical examination. The patient underwent a lobectomy. Frozen sections showed a spindle cell tumor of the thyroid gland. The nuclei of some of the tumor cells were obviously enlarged and deeply stained. Pseudocapsule invasion was observed in small foci. Samples showed neither mitosis nor necrosis and the nature of the tumor was difficult to determine. Paraffin sections showed a well-circumscribed nodular composed of intersecting fascicles of spindled to slightly epithelioid cells with eosinophilic cytoplasm and blunt-ended, cigar-shaped nuclei. We observed no significant nuclear atypia, mitotsis, or necrosis. Immunohistochemical staining showed the tumor cells to be positive for α-smooth muscle actin and h-caldesmon but negative for TG, TTF1, PAX8, S-100, CT, CK, and CD34. The ki-67 index was very low (<1%). Primary thyroid leiomyoma is rare and difficult to diagnose using frozen sections. Diagnosis requires immunohistochemical staining. Leiomyoma may be mistaken for other thyroid tumors also characterized by spindle cells.

scholarly journals Simultaneous light and electron microscopic observation of immunolabeled liver 27 KD gap junction protein on ultra-thin cryosections.

1987 ◽  
Vol 35 (3) ◽  
pp. 387-392 ◽  
Author(s):  
R Dermietzel ◽  
B Yancey ◽  
U Janssen-Timmen ◽  
O Traub ◽  
K Willecke ◽  
...  
Keyword(s):  
Gap Junctions ◽  
Gap Junction ◽  
Polyclonal Antibodies ◽  
Electron Microscopic Observation ◽  
Major Constituent ◽  
Frozen Sections ◽  
Electron Microscopic ◽  
Junction Protein ◽  
Gap Junction Protein ◽  
Antigenic Targets

We report on immunolabeling of gap junction protein in rat liver. Simultaneous light and electron microscopic immunolabeling of ultra-thin frozen sections was performed to confirm that the antigenic targets of polyclonal antibodies and a monoclonal 27 KD antibody (12/1 C5) are the gap junctions. Our results clearly demonstrate that the immunoreactive sites determined by indirect immunofluorescence correspond to immunogold-labeled gap junctions identified in the same section according to electron microscopic criteria. Our results also support the concept that the 27 KD protein is a major constituent of gap junctions.

scholarly journals Modafinil potentiates cocaine self-administration by a dopamine-independent mechanism: possible involvement of gap junctions

2020 ◽  
Vol 45 (9) ◽  
pp. 1518-1526 ◽  
Author(s):  
Maddalena Mereu ◽  
Takato Hiranita ◽  
Chloe J. Jordan ◽  
Lauren E. Chun ◽  
Jessica P. Lopez ◽  
...  
Keyword(s):  
Gap Junctions ◽  
Self Administration ◽  
Independent Mechanism

scholarly journals Effect of Fixation and Epitope Retrieval on BrdU Indices in Mammary Carcinomas

2000 ◽  
Vol 48 (3) ◽  
pp. 355-362 ◽  
Author(s):  
John N. McGinley ◽  
Katrina K. Knott ◽  
Henry J. Thompson
Keyword(s):  
Cell Proliferation ◽  
Prospective Studies ◽  
Immunohistochemical Staining ◽  
Staining Technique ◽  
Labeling Index ◽  
Antigen Retrieval ◽  
Frozen Sections ◽  
Mammary Carcinomas ◽  
Incorporated Brdu ◽  
Formalin Fixed

Studies in which 5-bromo-2′-deoxyuridine (BrdU) is used to quantify rates of cell proliferation are conducted prospectively. Therefore, the opportunity exists to select conditions that optimize detection of the BrdU epitope. The objective of this study was to quantify the extent to which the BrdU epitope was masked by formalin vs methacarn fixation in the assessment of cell proliferation. Mammary carcinomas from animals pulse-labeled with BrdU were trisected. A portion was frozen and the remaining two portions were fixed in 10% neutral buffered formalin or methacarn for 24 hr, processed, embedded in paraffin, and sections stained for incorporated BrdU using a peroxidase immunohistochemical staining technique. Antigen retrieval techniques also were applied to formalin-fixed sections. Fixation in methacarn gave the highest labeling index (16.4%), which was comparable to that observed in unfixed frozen sections (17.5%). Formalin fixation alone dramatically suppressed the labeling index (0.3%), which was only partially recovered using various antigen retrieval techniques (2.1-8.1%). Methacarn fixation is recommended for prospective studies in which BrdU detection is planned because of the quantitative recovery of epitope and the simplicity of the approach.

Preconditioning in the absence or presence of sustained ischemia modulates myocardial Cx43 protein levels and gap junction distribution

2001 ◽  
Vol 79 (5) ◽  
pp. 371-378 ◽  
Author(s):  
Pascal Daleau ◽  
Sophie Boudriau ◽  
Monia Michaud ◽  
Christine Jolicoeur ◽  
John G Kingma Jr
Keyword(s):  
Spatial Distribution ◽  
Gap Junctions ◽  
Gap Junction ◽  
Ischemic Preconditioning ◽  
Coronary Occlusion ◽  
Progressive Increase ◽  
Cx43 Protein ◽  
Protein Levels ◽  
Ischemic Region ◽  
Initial Decrease

In the heart, brief repeated episodes of ischemia prior to a sustained occlusion (ischemic preconditioning; PC) significantly delay the onset of necrosis and arrhythmogenesis. Ischemia has been reported to influence gap junction organization and connexin43 (Cx43) content, but whether PC affects these structures is not known. We investigated the effect of PC (2 cycles of 5-min ischemia plus 10-min reperfusion) followed by prolonged reperfusion without concomitant regional coronary occlusion on the myocardial Cx43 content and its spatial distribution in rabbit hearts. We also compared the effect of sustained ischemia with or without PC on Cx43 spatial distribution. In experiments with PC only, there was an initial decrease in Cx43 levels within the ischemic zone followed by a progressive increase after 48 h reperfusion. End–to–end immunolabeling of Cx43 was augmented in the ischemic region between 24 and 48 h reperfusion; labeling was not uniquely confined to myocyte abutments, but was also dispersed along the sarcolemma. Cx43 immunolabelling was more intense and diffuse in hearts subjected to PC before sustained coronary occlusion (compared to non-PC). These data indicate that gap junctions are significantly altered during brief episodes of ischemia. Reorganization of the gap junction complex could contribute to PC-mediated reductions in cardiac arrhythmias.Key words: ischemic preconditioning, connexin43, gap junction, reperfusion, heart.

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