Neuromuscular transmission in dystrophic mice

1977 ◽  
Vol 40 (4) ◽  
pp. 836-843 ◽  
Author(s):  
S. Carbonetto
Keyword(s):  
Neuromuscular Transmission ◽  
Neuromuscular Junctions ◽  
Large Population ◽  
Muscle Fibers ◽  
Dystrophic Muscle ◽  
Quantum Content ◽  
Quantal Size ◽  
Significant Difference ◽  
Release Of Acetylcholine ◽  
Dystrophic Mice

1. Neuromuscular transmission was studied in the extensor digitorum-longus muscle of dystrophic mice (strain 129/ReJ) by means of intracellular recording techniques. 2. In a large population of normal and dystrophic muscle fibers tested, the incidence of transmission failure was about 2% and showed no significant difference between the two groups. 3. Quantal size and quantum content of dystrophic junctions were found to be normal. This was true even of nerve terminal on apparently atrophied muscle fibers. 4. The facilitation ratio at dystrophic junctions was not significantly different from normal. 5. Dystrophic neuromuscular junctions exhibited an abnormality high frequency of giant spontaneous potentials. Application of tetrodotoxin (10(-6) M) and curare (10(-6) M) indicated that these potentials were caused by impulse-independent release of acetylcholine. 6. Neuromuscular transmission in dystrophic mice was found functionally normal and unrelated to the degenerative state of the muscle.

POSTSYNAPTIC EFFECTS OF HC-3 AT THE NEUROMUSCULAR JUNCTION OF THE FROG

1961 ◽  
Vol 39 (2) ◽  
pp. 343-349 ◽  
Author(s):  
A. R. Martin ◽  
R. K. Orkand
Keyword(s):  
Neuromuscular Junction ◽  
Intracellular Recording ◽  
Neuromuscular Transmission ◽  
Muscle Fibers ◽  
Marked Change ◽  
Single Muscle ◽  
End Plate ◽  
Quantum Content ◽  
Iontophoretic Application

Intracellular recording from single muscle fibers has been used to study the effects of hemicholinium No. 3 (HC-3) on neuromuscular transmission in the excised m. ext. l. dig. IV of the frog. Concentrations of HC-3 greater than 10−5 M decreased the amplitude of the end-plate potentials (e.p.p.'s) and the magnitude of the depolarization produced by iontophoretic application of acetylcholine. Neither a decrease in e.p.p. quantum content nor depolarization of the end plate accompanied the decreased e.p.p. amplitude. The duration of the potential produced by the application of ACh was increased and the falling phase of the e.p.p. prolonged. 10−4 M HC-3 produced a marked change in the shape of the e.p.p., the effect being similar to that produced by procaine.

Ca2+-dependent slow action potentials in normal and dystrophic mouse skeletal muscle

1983 ◽  
Vol 245 (5) ◽  
pp. C415-C422 ◽  
Author(s):  
L. M. Kerr ◽  
N. Sperelakis
Keyword(s):  
Skeletal Muscle ◽  
Action Potentials ◽  
Osmotic Shock ◽  
Muscle Fibers ◽  
Normal Muscle ◽  
Dystrophic Muscle ◽  
Recording Technique ◽  
Mammalian Muscle ◽  
Dystrophic Mice ◽  
Slow Action Potentials

Slowly rising action potentials (APs), previously described in amphibian skeletal muscle, were examined in skeletal muscle of normal and dystrophic mice (129/ReJ strain). A standard two-microelectrode recording technique was used. Muscles were bathed in a solution that was Cl- free (methanesulfonate substituted), high in K+ (20 mM), and contained 15 mM tetraethylammonium. The slow APs were elicited under conditions in which the fast Na+ channels were voltage inactivated (by partial depolarization) and in which the external Na+ concentration was only 10 mM. Increases in external Ca2+ concentration produced increases in slow AP amplitude and duration. Mn2+ (4 mM), La3+ (4 mM), and detubulation with osmotic shock blocked the slow APs. When slow APs were generated at 30-s intervals, their amplitude stayed constant. When they were generated at 15-s intervals, their amplitude decreased progressively and then fell to zero by the 11th stimulus. The Ca antagonists verapamil (10(-5) M) and bepridil (10(-5) M) caused this decrease in amplitude to occur more quickly. Voltage inactivation of the slow APs occurred between -45 and -10 mV. Slow APs recorded from dystrophic muscle fibers were decreased in amplitude and duration compared with those in normal fibers, and there was a reduced incidence of occurrence; 96% of the fibers in normal muscle exhibited slow APs compared with only 46% of dystrophic muscle fibers. In summary, slow Ca2+ APs in mammalian muscle are similar to those in cardiac and amphibian skeletal muscle, and these slow APs are depressed in dystrophic skeletal muscle.

scholarly journals A Retrospective Experience of Helicobacter pylori Histology in a Large Sample of Subjects in Northern Italy

Life ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 650
Author(s):  
Davide Giuseppe Ribaldone ◽  
Carlo Zurlo ◽  
Sharmila Fagoonee ◽  
Chiara Rosso ◽  
Angelo Armandi ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Large Population ◽  
Population Data ◽  
Signet Ring Cell ◽  
Current Data ◽  
Low Grade ◽  
Gastric Cardia Adenocarcinoma ◽  
Significant Difference ◽  
H Pylori ◽  
The Impact

Updated data about the prevalence of Helicobacter pylori (H. pylori) and its correlation with histological results are scarce. The aim of our study was to provide current data on the impact of H. pylori in a third-level endoscopy service. We performed a large, retrospective study analyzing the results of all histological samples of gastroscopy from the year 2019. In total, 1512 subjects were included. The prevalence of H. pylori was 16.8%. A significant difference between the prevalence in subjects born in Italy and those from eastern Europe, south America, or Africa was found (p < 0.0001, p = 0.006, and p = 0.0006, respectively). An association was found between H. pylori and active superficial gastritis (p < 0.0001). Current H. pylori and/or a previous finding of H. pylori was related to antral atrophy (p < 0.0001). Fifteen patients had low-grade dysplasia. There were no statistically significant associations with current or past H. pylori infection. One patient presented gastric cardia adenocarcinoma with regular gastric mucosa. One patient, H. pylori positive, was diagnosed with gastric signet ring cell adenocarcinoma in a setting of diffuse atrophy, without metaplasia.. Our study provides updated, solid (biopsy diagnosis and large population) data on the prevalence of H. pylori infection in a representative region of southern Europe.

scholarly journals Empiric use of anticoagulation in hospitalized patients with COVID-19: a propensity score-matched study of risks and benefits

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Bo Yu ◽  
Victor Perez Gutierrez ◽  
Alex Carlos ◽  
Gregory Hoge ◽  
Anjana Pillai ◽  
...  
Keyword(s):  
Mechanical Ventilation ◽  
Propensity Score ◽  
Propensity Score Matching ◽  
Major Bleeding ◽  
Risk Estimation ◽  
Large Population ◽  
Invasive Mechanical Ventilation ◽  
Bleeding Risk ◽  
Hospitalized Patients ◽  
Significant Difference

Abstract Background Hospitalized patients with COVID-19 demonstrate a higher risk of developing thromboembolism. Anticoagulation (AC) has been proposed for high-risk patients, even without confirmed thromboembolism. However, benefits and risks of AC are not well assessed due to insufficient clinical data. We performed a retrospective analysis of outcomes from AC in a large population of COVID-19 patients. Methods We retrospectively reviewed 1189 patients hospitalized for COVID-19 between March 5 and May 15, 2020, with primary outcomes of mortality, invasive mechanical ventilation, and major bleeding. Patients who received therapeutic AC for known indications were excluded. Propensity score matching of baseline characteristics and admission parameters was performed to minimize bias between cohorts. Results The analysis cohort included 973 patients. Forty-four patients who received therapeutic AC for confirmed thromboembolic events and atrial fibrillation were excluded. After propensity score matching, 133 patients received empiric therapeutic AC while 215 received low dose prophylactic AC. Overall, there was no difference in the rate of invasive mechanical ventilation (73.7% versus 65.6%, p = 0.133) or mortality (60.2% versus 60.9%, p = 0.885). However, among patients requiring invasive mechanical ventilation, empiric therapeutic AC was an independent predictor of lower mortality (hazard ratio [HR] 0.476, 95% confidence interval [CI] 0.345–0.657, p < 0.001) with longer median survival (14 days vs 8 days, p < 0.001), but these associations were not observed in the overall cohort (p = 0.063). Additionally, no significant difference in mortality was found between patients receiving empiric therapeutic AC versus prophylactic AC in various subgroups with different D-dimer level cutoffs. Patients who received therapeutic AC showed a higher incidence of major bleeding (13.8% vs 3.9%, p < 0.001). Furthermore, patients with a HAS-BLED score of ≥2 had a higher risk of mortality (HR 1.482, 95% CI 1.110–1.980, p = 0.008), while those with a score of ≥3 had a higher risk of major bleeding (Odds ratio: 1.883, CI: 1.114–3.729, p = 0.016). Conclusion Empiric use of therapeutic AC conferred survival benefit to patients requiring invasive mechanical ventilation, but did not show benefit in non-critically ill patients hospitalized for COVID-19. Careful bleeding risk estimation should be pursued before considering escalation of AC intensity.

Proportion of muscles spindles supplied by skeletofusimotor axons (beta-axons) in peroneus brevis muscle of the cat

1975 ◽  
Vol 38 (6) ◽  
pp. 1390-1394 ◽  
Author(s):  
F. Emonet-Denand ◽  
Y. Laporte
Keyword(s):  
Neuromuscular Junctions ◽  
Muscle Fibers ◽  
Repetitive Stimulation ◽  
Motor Axon ◽  
Dynamic Sensitivity ◽  
Conduction Velocities ◽  
Peroneus Brevis ◽  
Stimulation Of

Of 32 cat peroneus brevis spindles, 23 (72%) were found to be supplied by a least 1 skeletofusimotor or beta-axon. A motor axon was identified as skeletofusimotor when repetitive stimulation of it elicited both the contraction of extrafusal muscle fibers and as acceleration of the discharge of primary ending, which persisted after selective block of the neuromuscular junctions of extrafusal muscle fibers. The block was obtained by stimulating single axons at 400-500/s for a few seconds. Of 135 axons supplying extrafusal muscle fibers, 24 (18%) were shown to be beta-axons; 22 beta-axons had conduction velocities ranging from 45 to 75 m/s. All but three beta-axons increased the dynamic sensitivity of primary endings. Beta-innervated spindles may also be supplied by dynamic gamma-axons.

Smooth muscles from spastic coronary artery segments show hypercontractility to histamine

1990 ◽  
Vol 259 (1) ◽  
pp. H9-H13 ◽  
Author(s):  
S. Satoh ◽  
H. Tomoike ◽  
W. Mitsuoka ◽  
S. Egashira ◽  
H. Tagawa ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Coronary Artery ◽  
Coronary Arteries ◽  
Muscle Fibers ◽  
Coronary Spasm ◽  
Smooth Muscles ◽  
Bolus Administration ◽  
Luminal Diameter ◽  
Endothelial Denudation ◽  
Significant Difference

An animal model of coronary spasm was produced in Gottingen miniature pigs by a selective endothelial denudation of the coronary artery. Five months after the denudation, intracoronary bolus administration of 10 micrograms/kg histamine reduced the luminal diameter angiographically by 57 +/- 16 and 17 +/- 10% (P less than 0.01) in the previously denuded and contralateral control coronary arteries. Muscle fibers of 0.08–0.1 mm wide were prepared from circumferential bundles of the medial smooth muscle in the spastic and nonspastic coronary arteries. Upward shifts of either dose-tonic contraction relationships in Ca2(+)-containing solution or dose-monophasic contraction relationships in Ca2(+)-free solution were noted in muscle fibers taken from the spastic site compared with those from the nonspastic site with no difference between the mean effective dose values. After skinning the muscle fibers with saponin, there was no significant difference in the Ca2+ concentration-tension relationships between the two fibers. These findings suggest that an increased number of histaminergic receptors and/or augmentation of signal transduction, but not Ca2+ sensitivity of the contractile proteins in the medial smooth muscle cells, cause histamine-induced coronary hypercontraction.

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