scholarly journals Effects of cytochalasin D on occluding junctions of intestinal absorptive cells: further evidence that the cytoskeleton may influence paracellular permeability and junctional charge selectivity.

1986 ◽  
Vol 102 (6) ◽  
pp. 2125-2136 ◽  
Author(s):  
J L Madara ◽  
D Barenberg ◽  
S Carlson
Keyword(s):  
Electron Microscopy ◽  
Freeze Fracture ◽  
Structure And Function ◽  
Cytochalasin D ◽  
Absorptive Cell ◽  
Absorptive Cells ◽  
Charge Selectivity ◽  
Occluding Junctions ◽  
And Function ◽  
Junction Structure

Intestinal absorptive cells may modulate both the structure and function of occluding junctions by a cytoskeleton dependent mechanism (Madara, J. L., 1983, J. Cell Biol., 97:125-136). To further examine the putative relationship between absorptive cell occluding junctions and the cytoskeleton, we assessed the effects of cytochalasin D (CD) on occluding junction function and structure in guinea pig ileum using ultrastructural and Ussing chamber techniques. Maximal decrements in transepithelial resistance and junctional charge selectivity were obtained with 10 micrograms/ml CD and the dose-response curves for these two functional parameters were highly similar. Analysis of simultaneous flux studies of sodium and the nonabsorbable extracellular tracer mannitol suggested that CD opened a transjunctional shunt and that this shunt could fully account for the increase in sodium permeability and thus the decrease in resistance. Structural studies including electron microscopy of detergent-extracted cytoskeletal preparations revealed that 10 micrograms/ml CD produced condensation of filamentous elements of the peri-junctional contractile ring and that this was associated with brush border contraction as assessed by scanning electron microscopy. Quantitative freeze-fracture studies revealed marked aberrations in absorptive cell occluding junction structure including diminished strand number, reduced strand-strand cross-linking, and failure of strands to impede the movement of intramembrane particles across them. In aggregate these studies show that CD-induced perturbation of the absorptive cell cytoskeleton results in production of a transepithelial shunt which is fully explained by a defect in the transjunctional pathway. Furthermore, substantial structural abnormalities in occluding junction structure accompany this response. Lastly, the abnormalities in occluding junction structure and function coincide with structural changes in and contraction of the peri-junctional actin-myosin ring. These data suggest that a functionally relevant association may exist between the cytoskeleton and the occluding junction of absorptive cells. We speculate that such an association may serve as a mechanism by which absorptive cells regulate paracellular transport.

Use of human autoantibodies and immunoelectron microscopy to study structure and function of the nucleolus and nuclear bodies

1992 ◽  
Vol 50 (1) ◽  
pp. 506-507
Author(s):  
Robert L. Ochs
Keyword(s):  
Electron Microscopy ◽  
Structure And Function ◽  
Nuclear Bodies ◽  
Nuclear Interior ◽  
Coiled Bodies ◽  
Interchromatin Granules ◽  
And Function ◽  
Conventional Electron Microscopy ◽  
Perichromatin Granules ◽  
Perichromatin Fibrils

By conventional electron microscopy, the formed elements of the nuclear interior include the nucleolus, chromatin, interchromatin granules, perichromatin granules, perichromatin fibrils, and various types of nuclear bodies (Figs. 1a-c). Of these structures, all have been reasonably well characterized structurally and functionally except for nuclear bodies. The most common types of nuclear bodies are simple nuclear bodies and coiled bodies (Figs. 1a,c). Since nuclear bodies are small in size (0.2-1.0 μm in diameter) and infrequent in number, they are often overlooked or simply not observed in any random thin section. The rat liver hepatocyte in Fig. 1b is a case in point. Historically, nuclear bodies are more prominent in hyperactive cells, they often occur in proximity to nucleoli (Fig. 1c), and sometimes they are observed to “bud off” from the nucleolar surface.

Crystal Structures of Fragments D and Double-D from Fibrinogen and Fibrin

1999 ◽  
Vol 82 (08) ◽  
pp. 271-276 ◽  
Author(s):  
Glen Spraggon ◽  
Stephen Everse ◽  
Russell Doolittle
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Crystal Structures ◽  
Structure And Function ◽  
X Ray ◽  
Long Period ◽  
And Function

IntroductionAfter a long period of anticipation,1 the last two years have witnessed the first high-resolution x-ray structures of fragments from fibrinogen and fibrin.2-7 The results confirmed many aspects of fibrinogen structure and function that had previously been inferred from electron microscopy and biochemistry and revealed some unexpected features. Several matters have remained stubbornly unsettled, however, and much more work remains to be done. Here, we review several of the most significant findings that have accompanied the new x-ray structures and discuss some of the problems of the fibrinogen-fibrin conversion that remain unresolved. * Abbreviations: GPR—Gly-Pro-Arg-derivatives; GPRPam—Gly-Pro-Arg-Pro-amide; GHRPam—Gly-His-Arg-Pro-amide

Morphological and Biochemical Features Affecting the Antithrombotic Properties of the Aorta in Adult Rabbits and Rabbit Pups

1998 ◽  
Vol 79 (05) ◽  
pp. 1034-1040 ◽  
Author(s):  
E. Nitschmann ◽  
L. Berry ◽  
S. Bridge ◽  
M. W. C. Hatton ◽  
M. Richardson ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Gel Electrophoresis ◽  
Arterial Wall ◽  
Structure And Function ◽  
Wall Structure ◽  
Matrix Structure ◽  
Antithrombotic Activity ◽  
Antithrombin Activity ◽  
And Function ◽  
Biochemical Features

SummaryWe hypothesised that there are important physiologic differences in arterial wall structure and function with respect to antithrombotic activity in the very young (pre-puberty) compared to adults. Electron microscopy, gel electrophoresis, and activity assays were used to examine differences in aorta structure and function comparing prepubertal rabbits (pups) to adult rabbits. Differences in endothelial function, extracellular matrix structure, proteoglycan (PG) distribution and glycosaminoglycan (GAG) content and function were shown. In both intima and media, total PG, chondroitin sulfate (CS) PG and heparan sulfate (HS) PG content were significantly increased in pups compared to adult rabbits. These findings corresponded to increased concentrations by mass analyses of CS GAG and DS GAG in aortas from pups. There was also a significant increase in antithrombin activity in pups due to HS GAG. In conclusion, differences in both structure and antithrombin activity of aortas from pups compared to adult rabbits suggest that young arteries may have greater antithrombotic potential that is, at least in part, related to increased HS GAG.

Evaluation of neutrophil structure and function by electron microscopy: cytochemical studies

1999 ◽  
Vol 232 (1-2) ◽  
pp. 169-178 ◽  
Author(s):  
John M Robinson ◽  
Toshihiro Kobayashi ◽  
Harumichi Seguchi ◽  
Toshihiro Takizawa
Keyword(s):  
Electron Microscopy ◽  
Structure And Function ◽  
And Function

Gastroesophageal Junction: Structure and Function as Assessed by Using MR Imaging

Radiology ◽  
2010 ◽  
Vol 257 (1) ◽  
pp. 115-124 ◽  
Author(s):  
Jelena Curcic ◽  
Mark Fox ◽  
Elad Kaufman ◽  
Zsofia Forras-Kaufman ◽  
Geoffrey S. Hebbard ◽  
...  
Keyword(s):  
Mr Imaging ◽  
Gastroesophageal Junction ◽  
Structure And Function ◽  
And Function ◽  
Junction Structure

scholarly journals Canalicular domain structure and function in matrix-free hepatic spheroids

2020 ◽  
Vol 8 (1) ◽  
pp. 485-496 ◽  
Author(s):  
Vikas Raj Sharma ◽  
Ananya Shrivastava ◽  
Benoit Gallet ◽  
Elizaveta Karepina ◽  
Peggy Charbonnier ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Fluorescence Microscopy ◽  
Light Sheet ◽  
Structure And Function ◽  
Bile Canaliculi ◽  
Combined Use ◽  
3D Electron Microscopy ◽  
And Function ◽  
Matrix Free ◽  
Light Sheet Fluorescence Microscopy

The combined use of light sheet fluorescence microscopy and 3D electron microscopy enables to reveal the fine details of bile canaliculi structure and function in matrix-free hepatic spheroids.

Effect of basolateral acidification on the frog oxynticopeptic cell

1990 ◽  
Vol 259 (4) ◽  
pp. G564-G570 ◽  
Author(s):  
S. Arvidsson ◽  
K. Carter ◽  
A. Yanaka ◽  
S. Ito ◽  
W. Silen
Keyword(s):  
Electron Microscopy ◽  
Gastric Mucosa ◽  
Light And Electron Microscopy ◽  
Structure And Function ◽  
Intracellular Acidification ◽  
Intracellular Acidosis ◽  
Normal Morphology ◽  
And Function ◽  
Oxynticopeptic Cells

The effects of intracellular acidosis induced by acidification of the basolateral (nutrient) perfusate on the structure and function of the oxynticopeptic cell were studied in in vitro frog gastric mucosa. Changing the pH of the unbuffered nutrient perfusate (UNB) from 7.2 to 3.5 acidified the oxynticopeptic cell with no change in potential difference (PD) or resistance (R). Intracellular pH (pHi), PD, and R were 7.05 +/- 0.01, 16 +/- 1 mV, 165 +/- 7 omega.cm2 before and 6.44 +/- 0.01, 16 +/- 2 mV, 170 +/- 9 omega.cm2 after nutrient acidification. Acid secretion (H+) increased from 0.86 +/- 0.07 to 1.88 +/- 0.18 mu eq.cm-2.h-1. Addition of forskolin to tissues perfused with nutrient pH (pHn) 3.5 decreased PD to 2 +/- 2 mV and further increased H+ to 3.07 +/- 0.19 mu eq.cm-2.h-1. By light and electron microscopy oxynticopeptic cells perfused with UNB, pHn 3.5, appeared normal. Oxynticopeptic cells in tissues pretreated with omeprazole and then exposed to UNB, pHn 3.5, had extensive morphological damage. On increasing the pH of the nutrient perfusate from 3.5 to 7.2 there was prompt recovery of pHi in untreated and forskolin-stimulated mucosae (pHi 6.87 +/- 0.06 and 6.85 +/- 0.04) but no recovery of pHi in tissues pretreated with omeprazole or cimetidine (pHi 6.26 +/- 0.04 and 6.44 +/- 0.06, n = 6, 30 min after reexposure to UNB, pHn 7.2). We conclude that in a secreting mucosa intracellular acidification of the oxynticopeptic cell to pHi 6.4 is associated with normal morphology, PD, R, and increased H+, and that intracellular acidosis is not de facto deleterious.

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