Immunological comparison of acetylcholine receptors and their subunits from species of electric ray.
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Animals↗
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Ultrastructural plasticity in stimulated nerve terminals: pseudopodial invasions of abutted terminals in Torpedine ray electric organ.
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Animals↗
Some responses of the electric ray (Torpedo marmorata) to low ambient oxygen tensions.
I. Blood samples were taken during prolonged hypoxia experiments in which the inspired water oxygen tension was less than 10 mmHg. The oxygen tension of the post-branchial blood was about 5 mmHg and its pH shows a significant lowering from normoxic levels. 2. The decrease in blood pH is correlated with increases in levels of lactate and pyruvate. The lactate/pyruvate ratio increases during hypoxia. 3. An increase in blood succinate was also found, and strongly suggests the accumulation of multiple anaerobic end-products within the tissues. 4. Recovery of normoxic levels of succinate takes place almost immediately following the restart of ventilation whereas the decrease in lactate concentration is slower. 5. It is concluded that these adaptations may be related to the habitat of the fish at low tide in pools where the Po2 may fall very markedly.
Animals↗
[Cardiac amyloidosis: clinical, x-ray, electric, hemodynamic, developmental and pathological aspects. Apropos of 85 cases collected from French cardiology departments].
85 cases of cardiac amyloidosis have been collected from the university cardiac departments of France. Four distinct clinical pictures have emerged: 1. Primary cardiac amyloidosis (36 cases) which combines: congestive cardiac failure, ECG signs (extreme axis deviation, low voltage, signs of myocardial necrosis), arrhythmias (67%), and a rapidly fatal outcome (23.2 m +/- 8.5); 2. Cardiac amyloidosis associated with a marked neuromuscular amyloidosis (8 cases), in patients of Portuguese extraction (4 out of 8), with a positive family history (6 out of 8), characterised by arrhythmias (5 out of 8), and with a better prognosis (1 death out of 8); 3. Cardiac amyloidosis associated with a dysglobulinaemia (14 cases) with a clinical picture which is almost identical with that of primary cardiac amuloidosis; 4. Senile cardiac amyloidosis, whose frequency increases with age, may sometimes be discovered at routine post mortem examination, and is characterised by atrial fibrillation (13 out of 27) and its association with anaemia, signs of inflammation, and coronary atheroma.
Aged↗
Mitogenomic and phylogenomic analyses identify a cohesive Western Atlantic lineage within the Narcine complex (Torpediniformes: Narcinidae).
BACKGROUND: Accurate species delimitation within electric rays of the genus Narcine has been hindered by overlapping morphological characters and limited molecular resolution in previous single-locus studies. This study aims to evaluate phylogenetic relationships and species boundaries within the Narcine species complex across the Western Atlantic using complete mitochondrial genomes. METHODS AND RESULTS: Seven complete mitogenomes were newly assembled from individuals representing distinct morphotypes sampled across geographically widespread Western Atlantic localities and analyzed together with publicly available reference sequences. Mitochondrial protein-coding genes (PCGs) were examined using concatenated nucleotide and amino acid datasets under partitioned maximum-likelihood frameworks. Both approaches recovered highly congruent topologies, consistently supporting a single, well-defined western Atlantic mitochondrial lineage with low internal divergence (0.04-2.13%). Species delimitation analyses based on multiple methods yielded partially congruent results but consistently identified a dominant lineage encompassing all Atlantic samples. In contrast, two Colombian reference mitogenomes formed a separate and highly divergent lineage relative to the Atlantic group, despite showing moderate divergence between them. Comparative mitogenomic analyses revealed conserved genome organization, nucleotide composition bias, codon usage, and transfer RNA (tRNA) structures. All PCGs evolved under strong purifying selection, with Ka/Ks ratios well below unity. CONCLUSIONS: These results support mitochondrial genetic continuity across the Western Atlantic Narcine populations and do not provide mitochondrial evidence for multiple evolutionary lineages within the Western Atlantic. The marked mitochondrial divergence of Colombian reference mitogenomes highlights potential issues in sequence attribution and underscores the importance of data curation. Overall, complete mitochondrial genomes provide a robust framework for species delimitation and future integrative taxonomic assessments within Narcine.
Animals↗
Humoral antibodies to acetylcholine receptor in patients with myasthenia gravis.
Sera from patients with myasthenia gravis (M.G.) were studied by the quantitative micro-scale complement-fixation assay for the presence of humoral antibodies against acetylcholine receptor (AChR). The purified receptor was extracted from the electrogenic tissue of the electric ray, Torpedo californica. A significant difference in the antibody titres was observed between myasthenic and non-myasthenic patients. Out of fifteen patients with myasthenia gravis, at least 12 (80%) had antibodies against AChR. Only one case out of twenty-four controls had an indication of anti-receptor antibodies. In view of observations on the role of AChR as the autoantigen in myasthenia gravis, such antibodies may have significance in producing the neuro-muscular block characteristic of the disease.
Acetylcholine↗
The lipid composition of the electric organ of the ray, Torpedo marmorata, with specific reference to sulfatides and Na+-K+-ATPase.
The lipids from the electric organ of the ray, Torpedo marmorata, have been isolated and characterized. The major lipids were cholesterol, choline phospholipids, ethanolamine phospholipids, and sphingomyelins. The major fatty acids of ethanolamine phospholipids were 18:1, 18:0, 22:6, and 20:4. More than 50% of the acids in choline phospholipids were 16:0. The sphingomyelins consisted of five major ceramide species, all with sphingosine and the fatty acids 14:0, 15:0, 16:0, 22:1, and 24:1. The fatty acid 15:0 was mostly branched (n-2), a fatty acid earlier identified in sphingomyelins of the rectal gland of spiny dogfish. All long-chain bases were dihydroxy bases with a small percentage of branched chains. Sulfatides (cerebroside sulfate) made up the largest glycolipid fraction. The polar moiety wase galactose-3-sulfate. The fatty acids were normal and 2-hydroxy; the homologue 24:1 was the most abundant in both types of fatty acids. Most fatty acids were higher homologues of mono-unsaturated acids, but normal 18:0 fatty acid was also found. The long-chain bases were both dihydroxy and trihydroxy, with very small amounts of branched chains. The two major ceramide species of sulfatides were sphingosine combined with normal and hydroxy 24:1 fatty acids, respectively. Smaller amounts of trihydroxy base (18:0) were found linked to hydroxy 24:1 fatty acid, but not to its normal homologue. The cerebrosides contained the two major species mentioned above but lacked the trihydroxy base-hydroxy fatty acid species. The ratio of the activity of Na+-K+-dependent ATPase (EC 3.6.1.3) and the concentration of sulfatides was similar to ratios found for other tissues with normal and increased Na+ and K+ transporting capacity. The significance of this finding is discussed.
Animals↗
[Acetylcholinesterase from the electric organ of the ray Torpedo marmorata].
Studies have been made on substrate specificity of acetylcholinesterase (AChE;EC 3-1-1-7) from the electric organ of the ray T. marmorata with respect of choline and thiocholine esters, as well as on the effect of pH, salts and organophosphorus inhibitors (OPI) on the activity of the enzyme. Acetylcholine (ACh), propionycholine (PrCh) acetyl-beta-methylcholine (MeCh), acetylthiocholine ((ATCh) and propionylthiocholine (PrTCh) were hydrolyzed by the enzyme studied at the following relative rates-100: 28.8: 18.3: 87.2: 18.9 correspondingly. In all the cases, inhibition of the enzyme by high concentrations of the substrate was observed. As compared to other AChE, the enzyme from T. marmorata exhibits the highest affinity to ACh. For all the substrates studied, pH dependence of AChE activity followed the curve with maximum 7.5 for ACh and PrCh, 8.0-8.5 for ATCh and MeCh and 7.5-8.5 for PrTCh. Various salts (MgCl2), KCl, NaCl, NaBr, KI) increased AChE activity, the increase being the highest with MgCl2 (3.3 times) and NaCl (2.5X). Biomolecular rate constants ((k) II) for the interaction of AChE investigated with OPI containing cationic group-methylsulfomethylates, O-ethyl-S-(beta-ethylmercapto) ethylmethylthiophosphonate and O,O-diethyl-S-(beta-ethylmercapto) ethylthiophosphate, as well as methyl iodide O,O-disopropyl-S-(beta-phenylmethylamino) ethylphosphate-were significantly higher as compared with k(II) values for corresponding compounds without the cation. The value of k(II) sharply decreased with the increase in the size of the acyl radicals at phosphorus atom in the molecule of OPI.
Acetylcholine↗
Determination of the dew point and the frost point below 0 degrees C making use of the beta-ray backscattering and the electric conductivity on the narrow surface of insulated layer.
It is necessary to distinguish between the dew point and the frost point below 0 degrees C. The freezing of the dew and the melting of the frost are respectively detected by the rapid decrease and the increase of the conduction current on the narrow surface of insulated layer made of epoxy, 0.5 mm in width and 10 mm in length, on which the dew deposits. The dew point -9 degrees C and the frost point -8 degrees C in the humidity 21% at the temperature 13 degrees C are clearly distinguished in this method.
Background Radiation↗
On opiates, pain, and the nervous system.
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Electric Stimulation↗
Immunology of the acetylcholine receptor.
Myasthenia gravis is a spontaneously occurring autoimmune disease in which antibodies and lymphocytes are specifically reactive with nicotinic ACh receptors of skeletal muscle. Antibodies reactive with junctional receptors of human muscle are found in 90% of patients with myasthenia gravis and not at all in other diseases. Their capacity to cross the placenta suggests their involvement in the pathogenesis of neonatal myasthenia. The role of the thymus in myasthenia gravis remains a mystery, but it has a recently been established that the thymus contains nicotinic ACh receptors and that anti-receptor antibodies are present in myasthenic thymuses. Antibodies of myasthenic patients detect only partial cross reactivity between ACh receptors of different species. However, greater antibody binding is observed with receptors isolated from denervated rat muscle than with receptors from normal rat muscle. This suggests that extrajunctional and junctional ACh receptors might express different antigenic determinants. Although human antibodies bind minimally to ACh receptors of the electric organs of eels and marine rays, lymphocyte reactivity to electric eel receptors is found in high incidence in myasthenic patients. This suggests that electric organ and mammalian muscle ACh receptors may share more lymphocyte-defined than serologically-defined antigenic determinants. Both cellular and humoral immune responses to ACh receptors can be induced experimentally. Sufficient antigenic homology exists between receptors of different species that electric organ receptors are capable of inducing in mammals experimental autoimmune myasthenia gravis. Syngeneic muscle receptor also is immunogenic in rats. Induction of both myasthenia and antibodies to ACh receptor requires participation of thymus-derived lymphocytes. The majority of ACh receptors in myasthenic rat muscle exist complexed with antibody, but antibody is not bound directly to the receptor's ACh-binding site. Anti-receptor antibodies in vitro are capable of impairing the electrophysiological function of ACh receptors with minimal blocking of the ACh-binding site and in the absence of complement. Thus, myasthenia gravis and its experimental model provide unique biological tools for studying the structure, function and pathology of cell membrane receptors.
Acetylcholine↗
Electrotherapy and the X-ray.
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Electric Stimulation Therapy↗
Atmospheric derivatives of anaesthetic gases as a possible hazard to operating-room personnel.
During surgical procedures in which nitrous oxide (N2O) anaesthesia was administered there was an increased concentration of both nitric oxide (NO) and nitrogen dioxide (NO2) in operating-room air. Preliminary studies suggest that the use of certain devices (e.g., electric cauteries, X-ray machines) capable of releasing energy in the operating-room produce the oxidation of nitrous oxide. Further evaluation of gas phase reactions of anaesthetic agents within the operating-room appear warranted, particularly in relation to the occupational risks of operating-room personnel.
Abnormalities, Drug-Induced↗
Effect of benzyl alcohol on lipid bilayers. A comparisons of bilayer systems.
The effect of the small anesthetic molecule, benzyl alcohol, on the structure of various bilayer system has been studied by optical, electrical, and x-ray diffraction techniques. We find that the modifications in bilayer thickness caused by benzyl alcohol differ dramatically for planar (or black lipid) bilayers containing solvent, planar bilayers containing little or no solvent, and vesicular bilayers. Benzyl alcohol increases the thickness of planar bilayers containing n-alkane solvents, yet decreases the thickness of "solvent-free" planar bilayers. The effect of benzyl alcohol on vesicular bilayers below the phase transition temperature also depends on whether solvent is present in the bilayers. Without solvent, gel-state bilayers are reduced in thickness by benzyl alcohol, whereas in the presence of solvent, the thickness is unchanged. Above the phase transition temperature, benzyl alcohol has no measurable effect on vesicular bilayer thickness, whether solvent is present or not. These results indicate that different model membrane systems respond quite differently to a particular anesthetic.
Benzyl Alcohol↗
[Sturctural outline of spontaneous motor activity monitor using infrared photoelectric switch for small animals (author's transl)].
A simple monitor was developed for measuring the spontaneous motor activity (SMA) of small laboratory animals. The monitor was designed to measure animal ambulation along a horizontal axis by means of two infrared photo-beams. Using the monitor, male mice 7 to weeks of age at the commencement of this experiemtn showed high SMA values for the first 15 min and low values for the last 15 min of the experiment.
Animals↗
[Isothermal ordering processes of equiatomic alloy CuPt (author's transl)].
Isothermal ordering processes of equiatomic alloy CuPt quenched from above the critical temperature were investigated by means of electrical resistivity measurements, X-ray diffraction and electron microscopic observations. The main results obtained are as follows; (1) two different orderings are recognized at above and below 560 degrees C. Each main reaction is an ordering process having the activation energies of 30.6 and 17.4 kcal/mol, respectively. (2) In the early stage of ordering at the temperature below 200 degrees C the growth of disperse order is recognized by the increment of electrical resistivity, and has an activation energy of 30.1 kcal/mol. (3) At the temperature between 300 degrees C and 560 degrees C, the process of ordering consists of three stages having an activation energy of 17.4, 23.6 and 65.3 kcal/mol, respectively. These correspond to the ordering processes by the migration and the annihilation of quenched-in excess vacancies, the annihilation of secondary defects and the diffusion of equilibrium vacancies, respectively. (4) At the temperature above 560 degrees C, the process of ordering consists of two stages. The bulk of the ordering is a homogenous ordering within the grain.
Copper↗
Electrical apparatus used in medicine before 1900.
The Ancients had at their disposal torpedo fish, amber and magnets. It was not until the sixteenth century that ideas on the strange behaviour of amber and magnets were put forward. The eighteenth century saw the application of Newton's theories of matter and the introduction of the electrostatic machine, Galvanism and Volta's battery. In the nineteenth century there was extensive application of electricity in medical practice, with the development of electrocautery apparatus and illuminated cystoscopes, the pioneering of the electrocardiogram and the discovery of X-rays.
Electric Stimulation↗
Kinetics of cation-induced aggregation of Torpedo electric organ synaptic vesicles.
Synaptic vesicles from the Torpedo ray can be induced to aggregate in the presence of Ca2+ and K+ in the 4 mM and 50 mM range, respectively. The reactions are strikingly similar to those of chromaffin granule membranes reported previously (Morris, S.J., Chiu, V.C.K. and Haynes, D.H. (1979) Membrane Biochem. 2, 163-202). The Ca2+-induced reaction includes dimerization and higher order aggregation, and is shown to be due to electrostatic screening interactions and bindng to negatively-charged groups on the membrane surface. The K+-induced reaction includes only dimerization and is shown to be due to screening interactions alone. The kinetics of the dimerization reactions were studied using the stopped-flow rapid mixing technique. The Ca2+-induced reaction has a 'bimolecular' rate constant of 4.77 . 10(8) M-1 . s-1. These values are close to the limit of diffusion control (8.03 . 10(9) M-1 . s-1), indicating that no large energy barriers or structural barriers to aggregation exist. Arrhenius plots for the Ca2+-induced aggregation showed a break at 5 degrees C. Above this temperature, the activation energy is low (+0.65 kcal/mol), consistent with the above. Below this temperature, the activation energy is high, consistent with a membrane structure change increasing theenergetic and structural barriers. This information, and the observation of a high stability constant of the complex, were taken as evidence for the involvement of 'recognition sites' on the membrane surface. The results were analyzed in terms of an encounter complex model in which vesicles with separations of 26-126 A are considered capable of transformation into a stable complex. The rate constant of the transformation step is 1.4 . 10(3) s-1 for Ca2+ and approx. 1.6 . 10(5) s-1 for K+. The values are compared with previous results for chromaffin granule membranes and for phospholipid vesicles derived from chromaffin granule lipids and from acidic phospholipids. The half-time for Ca2+-induced transformation of the encounter complex into the stable complex is 435 microseconds. It is concluded that the recognition sites are almost as optimally deployed as the vesicle plasma membrane recognition sites involved in exocytotic release.
Animals↗