Effect of progesterone on the sodium transporting mechanism of isolated toad skin.
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Animals↗
Biomedical subjects
L Quevedo
Publications and source records attributed to L Quevedo.
Effect of progesterone on the sympathetic response of a frog nerve-skin preparation.
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Animals↗
Blockade of electrophysiological properties of muscle fibres by lycorine.
This study concerns the action of the alkaloid lycorine on electrophysiological properties of single sartorius muscle fibres. Lycorine caused a decrease of the resting membrane potential, a lengthening in the rise and decay times of the action potential and a fall of the muscle accommodation. The depolarizing effect was not affected when Na+ is replaced by choline in the Ringer solution. Lycorine did not inhibit the (Na+ + K+) ATPase activity. The results suggest that action of lycorine on the electrophysiological properties can be attributed to an interference with potassium channels.
Action Potentials↗
Accommodation of skeletal muscle in rats under hypoxic conditions induced by tourniquet.
Resting membrane potential (RMP) and indexes of accommodation (IA) were obtained from the brachioradialis muscle in rats subjected to 2 or 5 h of bilateral hindlimb tourniquet. The results showed a highly significant increase in muscular IA with a return to the control values for the rats with 2 h of tourniquet, while the increased in the IA is maintained all the survival period in the rats with 5 h of tourniquet. The velocity of increasing of the IA bears a direct relationship to the outcome of the injury. A decrease in the RMP of the brachioradialis muscle and an increase in the extracellular K+ and H+ was also observed. The early differences in the behavior of the accommodation parameter allowed a clear differentiation of the rats which survived the tourniquet shock from those who finally died.
Animals↗
Electrophysiological effects of methyl 3-O-methyl gallate on single muscle fibres.
The electrophysiological changes induced by methyl 3-O-methyl gallate, a substance extracted from Crinodendron hookerianum, have been studied on 32 muscle fibres of Pleurodema thaul. Four concentrations were used: 1 x 10(-5), 2 x 10(-5), 1 x 10(-4), and 2 x 10(-4) mol/l, the results being a reversible dose-dependent reduction of the overshoot and the amplitude of the action potential, a prolongation of the rise and decay times of the spike, as well as a depolarization of the resting membrane potential. An explanation of these results by a blockade of the potassium and possibly the sodium channels in the cellular membrane is discussed.
Action Potentials↗
Nerve accommodation in chronic alcoholic subjects.
Chronaxie, rheobase, conduction velocity and nerve accommodation of 50 alcoholic subjects were studied by applying rectangular and exponentially rising currents to the median nerve. A statistically significant decrease in nerve accommodation indexes and a change in the slope of the accommodation curve were found. The results show that nerve accommodation is more sensitive than other excitability parameters and should be used in the diagnosis and prognosis of alcoholic neuropathies.
Adult↗
The effects of methyl-3-O-methyl gallate on isolated nerve activity.
Methyl-3-O-methyl gallate (M30MG), extracted from Crinodendron hookerianum Gay, decreased both sciatic nerve accommodation and the amplitude of the compound action potential and increased the threshold to rectangular and exponential currents applied to the isolated sciatic nerve in a manner similar to that observed when tetrodotoxin is applied to the nerve. M30MG would act mainly on the large nerve fibres by a mechanism probably resembling that of tetrodotoxin.
Animals↗
Accommodation related to the action of ethanol on frog sciatic nerve.
Index of accommodation of 32 frog sciatic nerves was studied with exponentially rising currents. Ethanol was mixed with normal Ringer's solution at the following concentrations: 42, 85, 171, and 513 mM. We found a significant increase in the accommodation index. The results were attributed to the sodium conductance change and to a drop in membrane potential elicited by ethanol. The loss of the breakdown in the nerve accommodation curve was interpreted as the ethanol acting mainly on the thinner nerve fibres rather than on the large fibres.
Action Potentials↗
Effects of ethanol on compound action potential and refractory periods of toad sciatic nerve.
The action of ethanol on compound action potential, refractory periods and chronaxia are analyzed in 28 isolated sciatic nerves of toads. 85 mM ethanol increases the compound action potential and decreases the refractory periods. 342 and 513 mM ehtanol decrease the compound action potential and increase the absolute and relative refractory periods. These biphasic effects are discussed in relation with changes in Na+ and K+ permeabilities and to the greater sensitivity of thin fibers to the chemicals.
Action Potentials↗
Evaluation of "chemical isolation" in 1,168 leprosy patients' homes.
"Chemical isolation" (treatment of open cases as a measure of control for transmission between contacts) is evaluated by a retrospective study of 7,232 household contacts of 1,168 leprosy patient homes. Contacts comparable in age and type of exposure were arranged in subgroups according to whether they were born before (Group A) or born after (Group B) beginning treatment of the index cases had begun. Additionally, the whole group of contacts, both of open (LL & BB) and closed (TT & I) cases were evaluated. Among comparable contacts of LL and BB cases, the infection rate in the contacts before initiation of treatment is higher than in that of contacts after initiation of treatment. The protection afforded by the treatment to the exposed group (Group B) is on the order of 66%. The morbidity occurring in the group born after the initiation of index case treatment apparently results from partial persistence of infectiousness of the case under treatment.
Adolescent↗
[Duodenal duplication cyst].
The duodenal duplication cyst is an uncommon inherited anomaly. Its etiology is related to malformations of the canal in the gastrointestinal duct during the formation of the embryo. It develops in the infancy period or during childhood, it is uncommon in adults. The most frequent finding, is abdominal mass, although it might appear along with obstructive symptoms, recidivante pancreatitis and digestive bleeding. The diagnosis is based on image methods (ultrasonics, radiology, computed tomography, CPRE), nevertheless its identification through ultrasonics is of great value. Therefore we consider important the introduction of a 72-year-old woman case, whose pre-surgery diagnosis was performed with ultrasonics and reaffirmed by all other image methods. We also mention the usefulness of inner-surgery ultrasonics, in the surgery case of this pathology.
Aged↗
[Leiomyosarcoma of the vena cava inferior. The correlation: ultrasound and fine-needle puncture biopsy].
The leiomyosarcoma of the inferior vena cava is a non-frequent tumor, mesenchymal, that has its origin in the smooth muscular tissue of the vascular wall. Its growth is slow and expansive, more frequently found on females. The symptomatology is related to the cava segment where it is located. The diagnosis is performed by ultrasonics, computed tomography and cavography, actually magnetic resonance acquires more and more importance. The treatment is specifically surgery along with radiotherapy and chemotherapy. A case of leiomyosarcoma of the inferior vena cava is presented in which diagnosis was performed using ultrasonics, tomography and cavography confirmed before surgery by biopsy punction with thin needle. In the diagnosis of this pathology it is described the use of intro-surgery ultrasonics.
Biopsy, Needle↗
[Break of the curve of accommodation of pulp nerves].
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Dental Pulp Test↗