scholarly journals Structure of rapidly frozen gap junctions.

1980 ◽  
Vol 87 (1) ◽  
pp. 273-279 ◽  
Author(s):  
E Raviola ◽  
D A Goodenough ◽  
G Raviola
Keyword(s):  
Gap Junctions ◽  
Corneal Endothelium ◽  
Time Course ◽  
Morphological Changes ◽  
Low Ph ◽  
Ciliary Epithelium ◽  
Rapid Freezing ◽  
Annular Gap ◽  
Living State ◽  
Smooth Membrane

The structure of gap junctions in the rabbit ciliary epithelium, corneal endothelium, and mouse stomach and liver was studied with the freeze-fracturing technique after rapid freezing to near 4 degrees K from the living state. In the ciliary epithelium, the connexons were randomly distributed, separated by smooth membrane matrix. In the corneal endothelium, both random and crystalline arrangements of the connexons were observed. In the stomach and liver, the connexons were packed but not crystalline. Experimental anoxia or lowered pH caused crystallization of the connexons within 20-30 min. In the ciliary epithelium, the effects of prolonged anoxia or low pH could not be reversed . In addition, invaginated or annular gap junctions increased in number, but their connexons were usually distributed at random. Rapid freezing thus demonstrates that gap junctions of different tissues are highly pleiomorphic in the living state, and this may explain their variations in structure after chemical fixation. The slow time-course and irreversibility of the morphological changes induced by prolonged anoxia or low pH suggest that connexon crystallization may be a long-term consequence rather than the morphological correlate of the switch to high resistance.

Morphological Changes in the Brain of Acutely Ill and Weight-Recovered Patients with Anorexia Nervosa

2014 ◽  
Vol 42 (1) ◽  
pp. 7-18 ◽  
Author(s):  
Jochen Seitz ◽  
Katharina Bühren ◽  
Georg G. von Polier ◽  
Nicole Heussen ◽  
Beate Herpertz-Dahlmann ◽  
...  
Keyword(s):  
Anorexia Nervosa ◽  
Cognitive Deficits ◽  
Time Course ◽  
Morphological Changes ◽  
Meta Analysis ◽  
Short Term ◽  
Clinical Prognosis ◽  
Qualitative Review ◽  
Brain Changes ◽  
The Brain

Objective: Acute anorexia nervosa (AN) leads to reduced gray (GM) and white matter (WM) volume in the brain, which however improves again upon restoration of weight. Yet little is known about the extent and clinical correlates of these brain changes, nor do we know much about the time-course and completeness of their recovery. Methods: We conducted a meta-analysis and a qualitative review of all magnetic resonance imaging studies involving volume analyses of the brain in both acute and recovered AN. Results: We identified structural neuroimaging studies with a total of 214 acute AN patients and 177 weight-recovered AN patients. In acute AN, GM was reduced by 5.6% and WM by 3.8% compared to healthy controls (HC). Short-term weight recovery 2–5 months after admission resulted in restitution of about half of the GM aberrations and almost full WM recovery. After 2–8 years of remission GM and WM were nearly normalized, and differences to HC (GM: –1.0%, WM: –0.7%) were no longer significant, although small residual changes could not be ruled out. In the qualitative review some studies found GM volume loss to be associated with cognitive deficits and clinical prognosis. Conclusions: GM and WM were strongly reduced in acute AN. The completeness of brain volume rehabilitation remained equivocal.

scholarly journals Low pH enhances connexin32 degradation in the pancreatic acinar cell

2014 ◽  
Vol 307 (1) ◽  
pp. G24-G32 ◽  
Author(s):  
Anamika M. Reed ◽  
Thomas Kolodecik ◽  
Sohail Z. Husain ◽  
Fred S. Gorelick
Keyword(s):  
Gap Junctions ◽  
Acinar Cell ◽  
Intercellular Communication ◽  
Pancreatic Acinar Cell ◽  
Low Ph ◽  
Extracellular Ph ◽  
Gap Junctional Intercellular Communication ◽  
Junction Protein ◽  
Clinical Conditions ◽  
Gap Junctional

Decreased extracellular pH is observed in a number of clinical conditions and can sensitize to the development and worsen the severity of acute pancreatitis. Because intercellular communication through gap junctions is pH-sensitive and modulates pancreatitis responses, we evaluated the effects of low pH on gap junctions in the rat pancreatic acinar cell. Decreasing extracellular pH from 7.4 to 7.0 significantly inhibited gap junctional intracellular communication. Acidic pH also significantly reduced levels of connexin32, the predominant gap junction protein in acinar cells, and altered its localization. Increased degradation through the proteasomal, lysosomal, and autophagic pathways mediated the decrease in connexin32 under low-pH conditions. These findings provide the first evidence that low extracellular pH can regulate gap junctional intercellular communication by enhancing connexin degradation.

Retinoic acid application to chick wing buds leads to a dose-dependent reorganization of the apical ectodermal ridge that is mediated by the mesenchyme

Development ◽  
1989 ◽  
Vol 106 (4) ◽  
pp. 691-705 ◽  
Author(s):  
C. Tickle ◽  
A. Crawley ◽  
J. Farrar
Keyword(s):  
Retinoic Acid ◽  
Gap Junctions ◽  
Time Course ◽  
Apical Ectodermal Ridge ◽  
Threshold Response ◽  
Epithelial Morphology ◽  
Early Effects ◽  
High Doses ◽  
Columnar Cells ◽  
Dose Dependent

Local application of retinoic acid to wing buds of chick embryos leads to dose- and position-dependent changes in the pattern of cellular differentiation. Early effects of retinoid treatment on the apical ectodermal ridge coordinate pattern changes and morphogenesis. The length of the apical ridge increases when additional digits will form but decreases when digits are lost. These changes in length can be understood in terms of a threshold response to the local retinoid concentration that results in either disappearance or maintenance of the ridge (Lee & Tickle, J. Embryol. exp. Morph. 90, 139–169 (1985)). Here, we have analysed the mechanisms involved in ridge disappearance by locally applying retinoic acid to the apex of stage 20 chick wing buds. With this treatment regime, low doses give duplicated digit patterns and higher doses truncations. The height of the apical ridge is progressively reduced with increasing doses of retinoid and the time course of ridge flattening indicates that the height of the ridge is correlated with bud outgrowth. With high doses of retinoic acid, the typical ridge, a pseudostratified epithelium in which the columnar cells are tightly packed, disappears and the epithelium at the tip of the bud consists of loosely packed cuboidal cells. Shortly after treatment, there is a decrease in the number of gap junctions between ridge cells. This early change in cell contacts suggests that gap junctions may be involved in maintaining epithelial morphology. When treated epithelium is recombined with untreated mesenchyme, an apical ridge is reestablished and distal structures can be generated. In contrast, when treated mesenchyme is recombined with the epithelium from normal buds, only proximal structures are formed. Therefore, retinoids can lead to a reorganization of the apical ectodermal ridge which is mediated and maintained by the mesenchyme.

scholarly journals Gap junction structures after experimental alteration of junctional channel conductance.

1985 ◽  
Vol 101 (5) ◽  
pp. 1741-1748 ◽  
Author(s):  
T M Miller ◽  
D A Goodenough
Keyword(s):  
Gap Junctions ◽  
Gap Junction ◽  
Electron Micrographs ◽  
Time Course ◽  
Structural Changes ◽  
Lucifer Yellow ◽  
Freeze Fracture ◽  
Channel Conductance ◽  
Experimental Alteration ◽  
Quick Freezing

Gap junctions are known to present a variety of different morphologies in electron micrographs and x-ray diffraction patterns. This variation in structure is not only seen between gap junctions in different tissues and organisms, but also within a given tissue. In an attempt to understand the physiological meaning of some aspects of this variability, gap junction structure was studied following experimental manipulation of junctional channel conductance. Both physiological and morphological experiments were performed on gap junctions joining stage 20-23 chick embryo lens epithelial cells. Channel conductance was experimentally altered by using five different experimental manipulations, and assayed for conductance changes by observing the intercellular diffusion of Lucifer Yellow CH. All structural measurements were made on electron micrographs of freeze-fracture replicas after quick-freezing of specimens from the living state; for comparison, aldehyde-fixed specimens were measured as well. Analysis of the data generated as a result of this study revealed no common statistically significant changes in the intrajunctional packing of connexons in the membrane plane as a result of experimental alteration of junctional channel conductance, although some of the experimental manipulations used to alter junctional conductance did produce significant structural changes. Aldehyde fixation caused a dramatic condensation of connexon packing, a result not observed with any of the five experimental uncoupling conditions over the 40-min time course of the experiments.

scholarly journals Morphological features of the corneal endothelium in patients with pseudoexfoliative glaucoma

2018 ◽  
Vol 11 (4) ◽  
pp. 31-44 ◽  
Author(s):  
Inessa S. Beletskaya ◽  
Sergey Yu. Astakhov ◽  
Natalya V. Tkachenko
Keyword(s):  
Endothelial Cell ◽  
Cell Density ◽  
Corneal Endothelium ◽  
Morphological Changes ◽  
Open Angle Glaucoma ◽  
Morphological Features ◽  
Endothelial Cell Density ◽  
Control Group ◽  
Eye Drops ◽  
Pseudoexfoliative Glaucoma

Purpose. To study the main morphological features of the corneal endothelium in patients with pseudoexfoliative glaucoma (PEG). Methods. We included 193 subjects aged from 55 to 75 years. The main study group (PEG) included 96 patients (192 eyes), the primary open angle glaucoma (POAG) group included 36 patients (72 eyes) with POAG, the PEX group included 31 patients (62 eyes) with pseudoexfoliation syndrome without glaucoma. The control group consisted of 30 healthy subjects (60 eyes). Main corneal endothelium parameters were evaluated using a non-contact endothelial microscope EM-935 (Haag Streit, Switzerland). Data were analyzed by STATISTICA 9 software for Windows. Results. The patients with PEG had lower endothelial cell density (ECD) in comparison to the control group (p < 0.01), and PEX group (p < 0.05). The polymegatism level in patients with PEG and POAG was higher than in the control group (p < 0.001, and p < 0.01, correspondingly). In patients with moderate and advanced PEG, the ECD was significantly lower (p < 0.01), and the polymegatism level was significantly higher (p < 0.01) than the same parameters in patients with early PEG. The lowest ECD and the highest polymegatism percentage were observed in PEG patients with more pronounced PEX manifestations, p < 0.05. No effect of IOP-lowering eye drops on the corneal endothelium parameters was revealed, p < 0.05. Conclusions. Significant morphological changes of the corneal endothelium (decreased endothelial cell density, increased polymegatism percentage) were revealed in patients with PEG. It was established that the severity of these changes is associated with the PEG and PEX severity. No effect of IOP-lowering eye drops on the corneal endothelium parameters was detected.

Evaluation of cellular plasticity in the collecting duct during recovery from lithium-induced nephrogenic diabetes insipidus

2013 ◽  
Vol 305 (6) ◽  
pp. F919-F929 ◽  
Author(s):  
Francesco Trepiccione ◽  
Giovambattista Capasso ◽  
Søren Nielsen ◽  
Birgitte Mønster Christensen
Keyword(s):  
Time Course ◽  
Morphological Changes ◽  
Collecting Duct ◽  
Lithium Treatment ◽  
Transition Element ◽  
Type A ◽  
Functional Markers ◽  
Intercalated Cells ◽  
Anion Exchanger 1 ◽  
Principal Cells

The cellular morphology of the collecting duct is altered by chronic lithium treatment. We have previously shown that lithium increases the fraction of type-A intercalated cells and lowers the fraction of principal cells along the collecting duct. Moreover, type-A intercalated cells acquire a long-row distribution pattern along the tubules. In the present study, we show that these morphological changes reverse progressively after discontinuation of lithium and finally disappear after 19 days from lithium suspension. In this time frame we have identified for the first time, in vivo, a novel cellular type positive for both intercalated and principal cells functional markers, as recognized by colabeling with H+-ATPase/aquaporin-4 (AQP4) and anion exchanger-1 (AE-1)/AQP2 and Foxi1/AQP4. This cell type is mainly present after 6 days of lithium washout, and it disappears in parallel with the long-row pattern of the type-A intercalated cells. It usually localizes either in the middle or at the edge of the long-row pattern. Its ultrastructure resembles the intercalated cells as shown both by differential interference contrast and by electron microscopy. The time course of appearance, the localization along the collecting duct, and the ultrastructure suggest that the cells double labeled for principal and intercalated cells markers could represent a transition element driving the conversion of intercalated cells into principal cells.

Abstract P502: Abnormal Myocyte Calcium Dynamics And The Resultant Contraction Band Formation Of The Rat Heart Under Irreversible Injury By Membrane Permeabilization

2021 ◽  
Vol 129 (Suppl_1) ◽  
Author(s):  
Yuma Morishita ◽  
Shoko Tamura ◽  
Kentaro Mochizuki ◽  
Yoshinori Harada ◽  
Hideo Tanaka
Keyword(s):  
Fluorescence Intensity ◽  
High Frequency ◽  
Time Course ◽  
Morphological Changes ◽  
Confocal Imaging ◽  
Band Formation ◽  
Contraction Band Necrosis ◽  
Scanning Confocal Microscopy ◽  
The Individual ◽  
Contraction Band

Ca 2+ overload is a cardinal feature of cardiomyocyte injury, and its progression to irreversible state leads to cell death. However, unknowns are the precise spatiotemporal changes in the myocyte Ca 2+ dynamics and the relevant cell morphology of irreversibly injured hearts. On the hypothesis that myocytes exhibit high-frequency Ca 2+ waves and contraction band necrosis in saponin-permeabilized injured heart, we observed changes in the Ca 2+ dynamics and the relevant morphological changes in the subepicardial myocardium of the Fluo4-loaded rat hearts (n = 14) by rapid-scanning confocal microscopy (100 frames/s) under Langendorff perfusion with 0.3 mM Ca 2+ -Tyrode solution including 0.4 % saponin at 30°C. Also performed was confocal imaging of tetramethylrhodamine methyl ester (TMRM) fluorescence of the myocardium. Under quasi-quiescence of the heart after dissection of the SA node, individual myocytes barely exhibited spontaneous Ca 2+ waves, whereas after commencement of saponin perfusion high-frequency (118 ± 9.7 /min/cell, mean ± SEM) Ca 2+ waves (hereafter, “agonal waves”) emerged within 1 min, showing asynchronous, oscillatory contractions in the individual myocytes with a V prop of 124 ± 2.5 μm/s (n = 60). Subsequently, the waves gradually decreased in frequency with concomitant slowing of its decay time course, and eventually, disappeared in 6 min; myocytes exhibited high, static Fluo4-fluorescence intensity. Along with the progression of Ca 2+ overload by saponin, the TMRM fluorescence intensity was discretely lost in individual myocytes. The myocytes showing the agonal waves exhibited contraction bands, i.e., band-like aggregations of the actin fibers. Under mechanical arrest of the heart by 2,3-butanedione monoxime (20 mM), saponin still induced the agonal waves with a frequency of 253 ± 10.6 /cell/min and V prop of 118 ± 2.1 μm/s (n = 60); however, contraction bands were barely seen.In conclusion, irreversible myocyte injury by saponin provoked agonal Ca 2+ waves and oscillatory contractions indicating progressive Ca 2+ overload and the following mitochondrial damage, which may provide deeper insights into understanding the mechanism of contraction band necrosis.

Annular Gap Junctions of the Equine Hoof Wall

1983 ◽  
Vol 116 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Doug Leach ◽  
Lynn Oliphant
Keyword(s):  
Gap Junctions ◽  
Annular Gap ◽  
Equine Hoof

Hypoxia during pregnancy in rats leads to early morphological changes of atherosclerosis in adult offspring

2009 ◽  
Vol 296 (5) ◽  
pp. H1321-H1328 ◽  
Author(s):  
Zhenhua Wang ◽  
Ziyang Huang ◽  
Guorong Lu ◽  
Ling Lin ◽  
Markus Ferrari
Keyword(s):  
Morphometric Analysis ◽  
Time Course ◽  
Morphological Changes ◽  
Adult Life ◽  
Inflammatory Cells ◽  
Prenatal Hypoxia ◽  
Control Group ◽  
Adult Offspring ◽  
Sprague Dawley ◽  
Maternal Hypoxia

Exposure to an adverse intrauterine environment increases the risk of cardiovascular disease later in adult life. However, the time course relationship between prenatal hypoxia and the onset of atherosclerosis in offspring remains unknown. The purpose of this study is to evaluate the role of reduced fetal oxygen supply on early development of atherogenesis in the adult offspring and further assess its susceptibility to sex-, hyperlipidemia-, and postnatal hypoxemia-related differences. Based on a 4 × 2 full factorial design consisting of four factors of maternal hypoxia, sex, hyperlipidemia, and postnatal hypoxemia, characteristics of growth were determined, and histopathological observation and morphometric analysis of the thoracic aortas were performed in Sprague-Dawley rat offspring. Intrauterine growth restriction, altered body shape at birth, and accelerated postnatal weight gain occurred in the maternal hypoxia group but did not occur in the control group. In 16-mo-old maternal hypoxia offspring, the thoracic aortas exhibited lesions similar to early events in atherosclerosis that involved impaired endothelial cells, thickening and fibration of intimas, infiltration of inflammatory cells to the subendothelial space, and migration and proliferation of vascular smooth muscle cells to the intima. In contrast, no detectable pathological changes were observed in the offspring without maternal hypoxia exposure. Morphometric analysis further demonstrated that prenatal hypoxia caused a significant thickening of intima ( P < 0.001) with a main effect of 5.5 μm, an approximately twofold increase compared with controls. In addition, there was a positive additive relationship between prenatal hypoxia and hyperlipidemia on the intimal thickness ( P < 0.05). There were no other main effects or interaction among these four factors. In summary, our results indicate that maternal hypoxia during pregnancy leads to early pathological appearances of atherogenesis in adult offspring. This effect was enhanced with hyperlipemia but was unaffected by postnatal hypoxia or sex.

In vivo time course of morphological changes and DNA degradation during the degeneration of castration-induced apoptotic prostate cells

1998 ◽  
Vol 294 (1) ◽  
pp. 153-160 ◽  
Author(s):  
Zhongting Hu ◽  
Takao Ito ◽  
Kazunari Yuri ◽  
Cangxia Xie ◽  
Hitoshi Ozawa ◽  
...  
Keyword(s):  
Time Course ◽  
Morphological Changes ◽  
Dna Degradation ◽  
Prostate Cells
Sign in / Sign up

Export Citation Format

Share Document