ÉTUDE QUANTITATIVE DE L'ACTIVITÉ CHOLINESTÉRASIQUE DE LA PLAQUE MOTRICE PAR VOIE D'HISTOPHOTOMÉTRIE

1956 ◽  
Vol 34 (5) ◽  
pp. 869-881 ◽  
Author(s):  
Par Marc Crevier ◽  
Léonard-F. Bélanger
Keyword(s):  
Cholinesterase Activity ◽  
Enzymic Activity ◽  
Microscopic Level ◽  
Single Motor ◽  
End Plate ◽  
Local Increase ◽  
Enzymic Reaction ◽  
Reaction Proceeds ◽  
Motor End Plate

The cholinesterase activity of the motor end plate has been determined in situ by histophotometry. It has been possible to establish statistically the probable value of the enzymic activity of a single motor end plate morphologically identified. Studying the rate of the enzymic reaction in function of time, temperature, and concentration of substrate, it became evident that the progressive deposition of the precipitate as the reaction proceeds is represented by a proportional and local increase in its concentration and not by its spreading over the fiber. Inhibition experiments with eserine and acetylcholine in excess have proved that with the substrates used, β-naphthylacetate and β-carbonaphthoxycholine, it is possible to identify independently acetylcholinesterase and cholinesterase activity at the level of the motor end plate, the former being in proportion of 90%. The acetylcholinesterase inactivation has been observed after intramuscular injections of eserine, indicating that pharmacological problems can be studied at the microscopic level by histophotometry.

ÉTUDE QUANTITATIVE DE L'ACTIVITÉ CHOLINESTÉRASIQUE DE LA PLAQUE MOTRICE PAR VOIE D'HISTOPHOTOMÉTRIE

1956 ◽  
Vol 34 (1) ◽  
pp. 869-881
Author(s):  
Par Marc Crevier ◽  
Léonard-F. Bélanger
Keyword(s):  
Cholinesterase Activity ◽  
Enzymic Activity ◽  
Microscopic Level ◽  
Single Motor ◽  
End Plate ◽  
Local Increase ◽  
Enzymic Reaction ◽  
Reaction Proceeds ◽  
Motor End Plate

The cholinesterase activity of the motor end plate has been determined in situ by histophotometry. It has been possible to establish statistically the probable value of the enzymic activity of a single motor end plate morphologically identified. Studying the rate of the enzymic reaction in function of time, temperature, and concentration of substrate, it became evident that the progressive deposition of the precipitate as the reaction proceeds is represented by a proportional and local increase in its concentration and not by its spreading over the fiber. Inhibition experiments with eserine and acetylcholine in excess have proved that with the substrates used, β-naphthylacetate and β-carbonaphthoxycholine, it is possible to identify independently acetylcholinesterase and cholinesterase activity at the level of the motor end plate, the former being in proportion of 90%. The acetylcholinesterase inactivation has been observed after intramuscular injections of eserine, indicating that pharmacological problems can be studied at the microscopic level by histophotometry.

HUMAN MOTOR END-PLATE CHOLINESTERASE ACTIVITY AND THE EFFECT OF ANTICHOLINESTERASE COMPOUNDS

1981 ◽  
Vol 377 (1 Myasthenia Gr) ◽  
pp. 852-853
Author(s):  
Tatsuji Namba ◽  
Shinya Tada ◽  
Masafumi Fujii ◽  
David Grob
Keyword(s):  
Cholinesterase Activity ◽  
End Plate ◽  
Motor End Plate ◽  
Human Motor

scholarly journals MOTOR END PLATE REACTIVITY TO DIVALENT METAL IONS HISTOCHEMICAL STUDIES

1967 ◽  
Vol 15 (5) ◽  
pp. 276-284 ◽  
Author(s):  
TOSHIO NAKAMURA ◽  
TATSUJI NAMBA ◽  
DAVID GROB
Keyword(s):  
Metal Ions ◽  
Metal Binding ◽  
Calcium Release ◽  
Cholinesterase Activity ◽  
Divalent Metal ◽  
Divalent Metal Ions ◽  
Alizarin Red ◽  
End Plate ◽  
Motor End Plate

Motor end plates in the tibialis anterior muscle of the rat were demonstrated by metal sulfide deposits following injection of aqueous solutions of lead, stannous, cadmium, zinc or cupric ions into the muscle in vivo or in vitro. The appearance of the end plates was similar to the structure demonstrated by cholinesterase staining, with visualization of the subneural apparatus. Neither metal binding nor cholinesterase activity was affected 4 weeks after dissection of the sciatic nerve, indicating that the metal binding site is postsynaptic. Freezing or formalin fixation of muscle prevented binding of all metal ions to the end plate without greatly affecting cholinesterase activity, indicating that these two activities of the end plate are distinct. Prior administration of acetylcholine, d-tubocurarine, neostigmine or diisopropyl fluorophosphate inhibited binding to the end plate of cadmium and zinc ions but did not alter binding of lead and stannous ions. By formation of a lake with alizarin red S previously injected in vivo intramuscularly, the release of calcium ions at the motor end plate following stimulation of the muscle through the nerve or administration of neostigmine was demonstrated. These results suggest a close relationship of the site of binding of divalent metal ions in the motor end plate to the site of calcium release, and a close but not identical relationship to the site of cholinesterase activity and the acetylcholine receptor.

scholarly journals ACETYLCHOLINESTERASE ACTIVITY IN THE MYOTUBE AND MUSCLE SATELLITE CELL OF THE FETAL RABBIT AN ELECTRON MICROSCOPIC-CYTOCHEMICAL AND BIOCHEMICAL STUDY

1973 ◽  
Vol 21 (7) ◽  
pp. 634-652 ◽  
Author(s):  
VIRGINIA M. TENNYSON ◽  
LEON T. KREMZNER ◽  
MIRO BRZIN
Keyword(s):  
Satellite Cell ◽  
Mononuclear Cell ◽  
Active Sites ◽  
Mononuclear Cells ◽  
Biochemical Study ◽  
Enzymic Activity ◽  
Muscle Satellite Cell ◽  
Electron Microscopic ◽  
End Plate ◽  
Motor End Plate

Acetylcholinesterase (AChE) activity has been studied in the myotube and in extrajunctional skeletal muscle of the rabbit fetus. Some observations on the developing motor end plate are included. Both insoluble and soluble AChE's are present at all stages, but butyrylcholinesterase seems to be absent. Enzymic activity is high during myotube formation. The insoluble AChE probably corresponds to the cytochemical end product which is bound to the elements of the reticulum in the myotube, i.e., the nuclear envelope, the sarcoplasmic reticulum and some elements of the Golgi complex. The possibility that the enzyme-containing reticulum is involved in the spontaneous contraction of early myotubes is discussed. The number of active sites of reticulum-bound enzyme decreases markedly as the myotubes mature into early muscle. The soluble AChE is probably derived from the AChE-containing mononuclear cell and the Schwann cell which accompanies the spinal nerve to the motor end plate. These cells have a random distribution of end product and are probably the source of a similar end product found at the surfaces of these cells and at the sarcolemma of adjacent myotubes. The following possibilities that are discussed are that soluble AChE may (a) play a role in fusion of myotubes, (b) be involved in widespread sarcolemmal acetylcholine sensitivity and (c) contribute to the junctional enzyme. The randomly distributed end product in the AChE-containing mononuclear cell permits the tracing of its further differentiation. This cell appears to be a stem cell, which can fuse directly with the myotube; it can give rise to a more differentiated type of myoblast, as well as to the muscle satellite cell. AChE-containing mononuclear cells may also contribute to the cells associated with the neuromuscular junction. The soluble AChE in the muscle satellite cell seems to be associated with an "active" phase of this cell, since enzymic activity is not seen in the adult stage in which it is presumed to be dormant.

scholarly journals DEVELOPMENT OF THE NEUROMUSCULAR JUNCTION

1972 ◽  
Vol 55 (1) ◽  
pp. 93-103 ◽  
Author(s):  
Thomas L. Lentz
Keyword(s):  
Schwann Cell ◽  
Cholinesterase Activity ◽  
Neuromuscular Junctions ◽  
Synaptic Cleft ◽  
Axon Terminals ◽  
End Plate ◽  
Motor End Plate ◽  
Motor End Plates

To determine the effects of nerve explants on the integrity of motor end plates in vitro, cholinesterase activity and structure of end plates were compared in newt muscle denervated in vivo, cultured in the absence of nerve explants, and cultured in the presence of sensory ganglia. In neuromuscular junctions denervated in vivo or in vitro, the synaptic vesicles become clumped and fragmented. A few intact vesicles escape into the synaptic cleft. Axon terminals degenerate until they are left as residual bodies within the Schwann cell cytoplasm. Junctional folds on the muscle surface are reduced in height and are no longer evident once traces of axoplasm within the Schwann cell disappear. End plate cholinesterase activity is reduced as junctional folds are lost. When muscle is cultured in the presence of a sensory ganglion, the terminal axoplasm degenerates in the same manner but junctional folds persist on the muscle surface. Moderately intense cholinesterase activity remains in association with the junctional folds, so that normal motor end plates are maintained in the absence of innervation. These results show that degenerative changes in the structure of the motor end plate and loss of cholinesterase activity occurring in organ culture as a result of denervation can be retarded by nerve explants that do not directly innervate the muscle.

The Fine Structure of Irradiated Mouse Heart

1976 ◽  
Vol 34 ◽  
pp. 184-185
Author(s):  
Vivian V. Yang ◽  
S. Phyllis Stearner
Keyword(s):  
Microscopic Level ◽  
Ultrastructural Changes ◽  
Mouse Heart ◽  
Blood Vessel Wall ◽  
Histopathological Changes ◽  
Light Microscopic Level ◽  
Γ Rays ◽  
Fission Neutrons ◽  
Total Body

The heart is generally considered a radioresistant organ, and has received relatively little study after total-body irradiation with doses below the acutely lethal range. Some late damage in the irradiated heart has been described at the light microscopic level. However, since the dimensions of many important structures of the blood vessel wall are submicroscopic, investigators have turned to the electron microscope for adequate visualization of histopathological changes. Our studies are designed to evaluate ultrastructural changes in the mouse heart, particularly in the capillaries and muscle fibers, for 18 months after total-body exposure, and to compare the effects of 240 rad fission neutrons and 788 rad 60Co γ-rays.Three animals from each irradiated group and three control mice were sacrificed by ether inhalation at 4 days, and at 1, 3, 6, 12, and 18 months after irradiation. The thorax was opened and the heart was fixed briefly in situwith Karnofsky's fixative.

In-Situ Study of Ti/TiN Stability under Nitrogen Anneal

1999 ◽  
Vol 564 ◽  
Author(s):  
P. W. DeHaven ◽  
K. P. Rodbell ◽  
L. Gignac
Keyword(s):  
Annealing Temperature ◽  
Time Range ◽  
Second Phase ◽  
Transformation Rate ◽  
Transformation Mechanism ◽  
Second Stage ◽  
Transmission Electron ◽  
Reaction Proceeds ◽  
Two Stages

AbstractThe effectiveness of a TiN capping layer to prevent the conversion of α-titantium to titanium nitride when annealed in a nitrogen ambient has been studied over the temperature range 300–700°C using in-situ high temperature diffraction and transmission electron microscopy. Over the time range of interest (four hours), no evidence of Ti reaction was observed at 300°C. At 450°C. nitrogen was found to diffuse into the Ti to form a Ti(N) solid solution. Above 500°C the titanium is transformed to a second phase: however this reaction follows two different kinetic paths, depending on the annealing temperature. Below 600°C. the reaction proceeds in two stages, with the first stage consisting of Ti(N) formation, and the second stage consisting of the conversion of the Ti(N) with a transformation mechanism characteristic of short range diffusion (grain edge nucleation). Above 600°C, a simple linear transformation rate is observed.

Activités cholinestérasiques dans le foie de Poulet Rôle de l'endoderme dans l'apparition d'activités cholinestérasiques dans la composante mésenchymateuse du tissu hépatique

Development ◽  
1971 ◽  
Vol 26 (3) ◽  
pp. 481-495
Author(s):  
Par Elisabeth Houssaint ◽  
Nicole Le Douarin
Keyword(s):  
Endothelial Cells ◽  
Chick Embryo ◽  
Cholinesterase Activity ◽  
Enzymic Activity ◽  
The Body ◽  
Hepatic Tissue ◽  
Experimental Procedure ◽  
Septum Transversum ◽  
Cholinesterase Activities

Cholinesterases in the chick liver. The role of the endoderm in the appearance of the activity of cholinesterases in the hepatic mesenchyme The histochemical method of Koelle & Friedenwald (1949), as modified by Gerebtzoff (1953), has been used to investigate the distribution of cholinesterases in the chick embryonic and adult liver. Non-specific cholinesterases and, in a lower proportion acetylcholinesterase, have been detected in the endothelial cells of blood sinusoids of both adult and embryonic hepatic tissue. The hepatocytes do not show any cholinesterase activity. Cholinesterases appear precociously in the liver mesenchyme, since they already occur in the septum transversum of the 3-day-old chick embryo. An experimental procedure preventing the invasion of the hepatic mesenchymal Anlage by the endodermic cords has been used. The experimentally isolated hepatic mesenchyme shows an important cholinesterase activity; therefore this activity does not depend on the presence of the hepatocytes. The grafting of the determined hepatic endodern in the somatopleura of the 3-day-old chick embryo results in the development of hepatic tissue in the body wall. In this experimentally produced liver, cholinesterase activities are present in the endothelial cells which have arisen from somatopleura mesenchymal cells, though normally somatopleural mesenchyme does not possess these enzymes. The role of the endoderm in the appearance of this enzymic activity in the somatopleural mesenchyme is discussed.

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