Assessment of sediment toxicity in San Vicente Bay, central Chile, using the amphipod Ampelisca araucana.
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Animals↗
Biomedical subjects
E Soto
Publications and source records attributed to E Soto.
Sensitivity of the meiofaunal copepod Tisbe longicornis to K2Cr2O7 under varying temperature regimes.
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Animals↗
Microcomputer decision support system for intensive care.
This article describes a computer system to support decisions in Intensive Medicine developed for a multipurpose Intensive Care Unit (13 beds and about 700 yearly patients). The system is used in a microcomputer (486DX4). Works done in this area are mentioned; and the different programs which integrate the system, the advantages of its use and the results accomplished are described. Some of the most important results are the quality increment of the medical care given, physicians' possibilities of dedicating more time to their patients, cost reductions, and improvements in the development of teaching and in the conditions to carry out research work in the Intensive Care Unit (ICU). An analysis is made of the system requirements that guarantee its integration to the Unit work, and the easy and safe use of it by the physicians and nurses.
Critical Care↗
A microcomputer program for automated neuronal spike detection and analysis.
A system for on-line spike detection and analysis based on an IBM PC/AT compatible computer, written in TURBO PASCAL 6.0 and using commercially available analog-to-digital hardware is described here. Spikes are detected by an adaptive threshold which varies as a function of signal mean and its variability. Since the threshold value is determined automatically by the signal-to-noise ratio analysis, the user is not actively involved in controlling its level. This program has been reliably used for the detection and analysis of the spike discharge of vestibular system afferent neurons. It generates the interval-joint distribution graph, the interval histogram, the autocorrelation function, the autocorrelation histogram, and phase-space graphs, thus, providing a complete set of graphical and statistical data for the characterization of the dynamics of neuronal spike activity. Data can be exported to other software such as Excel, Sigmaplot and MatLab, for example.
Ambystoma↗
Histochemistry and role of nitric oxide synthase in the amphibian (Ambystoma tigrinum) inner ear.
Nicotinamide adenine dinucleotide phosphate reduced-diaphorase (NADPH-d) histochemistry was investigated in the axolotl (Ambystoma tigrinum) inner ear. Hair cells showed an intense NADPH-d reaction; afferent neurones also stained but less intensely than hair cells. Effects of NG-nitro-L-arginine (L-NOARG) on the basal discharge and mechanical responses of semicircular canal afferent neurones recorded extracellularly were also studied. L-NOARG (1 mu M) diminished the basal discharge and the response of afferent neurones to sinusoidal mechanical stimuli to 45 +/- 6.4% and 65 +/- 5.3% (mean +/- SEM) of control value, respectively. These findings suggest that production of nitric oxide (NO) by hair cells and probably also by afferent neurones contributes to the basal discharge and the response of afferent neurones to mechanical stimuli.
Ambystoma↗
Antagonism of glutamate receptors by a chromatographic fraction from the exudate of the sea anemone Phyllactis flosculifera.
In the search for new glutamate antagonists it seems promising to characterize the effects of venom from invertebrates that prey mainly on crustaceans. In this work, the exudate of the sea anemone Phyllactis flosculifera was used as a source of this type of compound. The action of chromatographic fraction D from P. flosculifera was tested upon microion-tophoretically evoked glutamate responses in intracellular recordings from central neurons of the land snail Zachrysia guanensis. Bath application of fraction D (2-8 mg/ml, n = 13) diminished both the excitatory and the inhibitory components of glutamate agonists in Z. guanensis neurons; this action was dose-dependent and partially reversible. Fraction D actions were also tested in the multiunit spontaneous and mechanically evoked responses of the glutamatergic junction between hair cells and afferent neurons of the axolotl Ambystoma tigrinum. Pressure ejection of fraction D in concentrations ranging from 0.5 to 2 mg/ml (n = 9) decreased the spontaneous and mechanically evoked activity of semicircular canal afferent neurons and the responses evoked by kainic acid and alpha-amino-3-hydroxy-5-methylisoxasole-4-propionic acid. This action was also dose-dependent and partially reversible. These results indicate that fraction D acts as a glutamate receptor antagonist in snail and amphibian neurons. Further studies are required to characterize the active compounds responsible for this action and its specificity upon the subtypes of glutamate receptors.
Ambystoma↗
Are there any clinical signs and symptoms that are related to endometriosis in infertile women?
OBJECTIVE: Our purpose was to assess the physical signs and clinical symptoms associated with endometriosis in infertile women. STUDY DESIGN: This case-control study was carried out in an academic tertiary hospital. There were 174 infertile women with endometriosis and 174 infertile women without endometriosis, all of them studied by laparoscopy. Before laparoscopy a standard interview and a standard physical examination were performed. RESULTS: Cul-de-sac nodularity was more frequent in infertile women with endometriosis than in infertile women without endometriosis (6.3% vs 0%). Although uterosacral tenderness was also more frequent in infertile women with endometriosis (7.5% vs 1.7%), uterosacral tenderness without nodularity was similar in both populations. Uterine retroversion and cul-de-sac obstruction frequencies were somewhat higher in the endometriosis group (p<0.10). The remaining signs and symptoms analyzed, including pelvic pain and dysmenorrhea, were similarly frequent in both populations. Symptoms were similarly frequent in all American Fertility Society stages, although adnexal mass was higher in stage IV. CONCLUSION: Uterosacral nodularity was pathognomonic of endometriosis in infertile women. Uterosacral nodularity and uterosacral tenderness (associated with uterosacral nodularity) were the only symptoms or signs of value to indicate endometriosis in infertile patients. The remaining clinical signs, as well as clinical symptoms, were of no value in diagnosing endometriosis in infertile women.
Biopsy↗
Acute myocardial infarction in angiographically normal coronary arteries following induction of general anesthesia.
Coronary spasm may occur with angiographically normal and diseased coronary arteries. General anesthesia has been described only rarely as a triggering event for coronary artery spasm, and only once before in the presence of angiographically normal coronary arteries. We have now seen three patients presenting with acute ST-segment elevation following induction of general anesthesia with enzyme evidence of myocardial necrosis in two patients. Cardiac catheterization was performed in all three patients with one of the procedures performed on an emergency basis owing to hemodynamic compromise. All three patients demonstrated angiographically normal coronary arteries. The electrocardiograms and coronary arteriograms are presented, and possible mechanisms for the injury pattern seen on the electrocardiogram are discussed. Coronary vasospasm causing an acute injury pattern on the electrocardiogram can be caused by general anesthesia and has to be recognized promptly and treated appropriately to prevent more serious complications.
Anesthesia, General↗
NMDA-mediated potentiation of the afferent synapse in the inner ear.
In an isolated vestibular organ preparation from the axolotl (Ambystoma tigrinum), glycine (10-0.01 microM) perfusion had no effect in the resting control condition, but significantly modified the response of afferent fibres to mechanical stimuli, producing a slowly increasing discharge rate during sinusoidal mechanical stimulation periods. This action was dependent upon the stimulus duration and was antagonized by 7-chloro-kynurenic acid (7-ClKyn), 2-amino-5-phosphonopentanoic acid (AP5), N-allyl-nor-metazocina (MK-801) and extracellular magnesium. These results indicate that glycine modulates the afferent synapse in the vestibular organ, and that, NMDA receptors codify long lasting mechanical stimuli.
2-Amino-5-phosphonovalerate↗
Evidence for NMDA receptor in the afferent synaptic transmission of the vestibular system.
This study aimed to define the pharmacology and physiological role of the N-methyl-D-aspartate (NMDA) receptor in the synapse between the hair cells and primary afferent neurons in the vestibular system. The spontaneous and mechanically evoked spike discharges of vestibular nerve fibers were extracellularly recorded in isolated inner ear from the axolotl (Ambystoma tigrinum). Pressure ejection of NMDA (10(-6) to 10(-3) M) elicited a dose-dependent increase of the basal spike discharge from the vestibular nerve fibers. Extracellular magnesium antagonized the NMDA effect in a dose-dependent manner. D(-)-2-amino-5-phosphonovaleric acid (AP5, 10(-5) to 10(-3) M) and 7-chloro-kynurenic acid (7ClKyn, 10(-6) to 10(-3) M) inhibited the basal activity of the vestibular nerve fibers. 7ClKyn also diminished the responses elicited by the mechanical stimulation of the preparation. Glycine (10(-9) to 10(-6) M) applied by bath substitution enhanced the NMDA response, and the glycine agonist D-serine partially reversed the 7ClKyn inhibitory action. These results suggest that NMDA receptors participate in the generation of the basal spike discharge of vestibular system primary afferent neurons, but its activation is not critical for the response to brief mechanical stimuli.
2-Amino-5-phosphonovalerate↗
Postoperative intramyocardial abscess caused by mucormycosis.
We report the case of an intramyocardial abscess caused by mucormycosis that arose after cardiac operation. Several causes of immunosuppression in a 71-year-old woman were exacerbated after she underwent coronary revascularization. Before she died of multiple organ system dysfunction, a variety of supraventricular and ventricular arrhythmias, as well as complete heart block, developed, but the cause was not clear until autopsy revealed a large septal myocardial abscess due to mucormycosis.
Abscess↗
Osmosis: a microcomputer laboratory teacher.
A computer simulation of osmotic processes has been developed. Several experimental setups are graphically simulated and may be freely selected by the user. The simulation analyzes the basic factors which determine the osmotic pressure and volume flow of a solution (e.g. concentration, temperature, activity coefficient, Staverman's coefficient and external pressure). The program was written in Turbo Pascal to operate in IBM-PCs or compatibles. High quality graphical display of results maintains the students' interest. A user's guide and continuous help for the available options simplify its use. Computer simulation seems to be a very well suited aid for teaching osmotic phenomena, improving both theoretical knowledge and the ability of the students to empirically demonstrate some of the basic laws of osmotic phenomena.
Animals↗
Pipazethate lethality in a baby.
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Antitussive Agents↗
Streptomycin blocks the afferent synapse of the isolated semicircular canals of the frog.
This study aimed to define the acute electrophysiological effects of the perilymphatic perfusion of streptomycin in the sensory apparatus of the semicircular canals of the frog. The ampullary DC potential, the vestibular nerve multiunit discharge, the nerve DC potential and the unitary EPSP activity were recorded in isolated semicircular canals of the frog (Rana esculenta L). The results demonstrated that perilymphatic microperfusion of streptomycin (0.1, 0.3, 1 and 3 mM) reduced both resting and mechanically evoked afferent discharge, while the response of the hair cells remains unchanged. Intracellular recordings from single afferent axons showed that the reduction of the afferent discharge was mainly due to a reduction of the amplitude, but not the frequency, of the EPSPs. These results indicate that streptomycin, when applied in the fluid bathing the synaptic pole of the sensory cells, can act as an antagonist of the vestibular afferent transmitter at the postsynaptic level.
Afferent Pathways↗
Streptomycin blocks the postsynaptic effects of excitatory amino acids on the vestibular system primary afferents.
It has been suggested that streptomycin might be an antagonist of the glutamate receptors, and that it selectively blocks quisqualic acid receptors. We studied whether streptomycin blocks the responses to excitatory amino acid agonists on the vestibular system primary afferents, and if it allows us to differentiate between kainate (KA) and quisqualate (QA) receptor mediated responses. The experiments were performed in the axolotl (Ambystoma tigrinum). Intra- and extracellular records of the electrical activity of semicircular canal afferent fibers were obtained. Drugs were applied by pressure ejection in volumes of 20 microliters in a 10 ml bath. Streptomycin (0.01-10 mM), induced a dose dependent reversible inhibition of the basal spike discharge of the afferent fibers. This coincided with a reduction in the amplitude of excitatory postsynaptic potentials (EPSP) recorded intracellularly in the afferent fibers. Streptomycin also blocked the excitatory action produced by KA and QA; increasing concentrations of streptomycin produced a rightward shift in the concentration-response curves for both KA and QA. This action persisted even in a high Mg2+ (10 mM), low Ca2+ (0.09 mM) Ringer solution, indicating its postsynaptic nature. These results show that streptomycin might be a non-selective excitatory amino acid (EAA) receptor antagonist.
Ambystoma↗
Coronary artery spasm induced by anesthesia: a case report and review of the literature.
Anesthesia-induced coronary vasospasm has been reported only rarely. We report a case, without previous cardiac history, in which immediately after anesthesia induction a marked ST elevation was noted on the EKG monitor. Premature ventricular contractions as well as non-sustained ventricular tachycardia were noted. These changes resolved immediately after nitroglycerin infusion and 75 mg of lidocaine were given. A coronary angiogram revealed normal coronary arteries and left ventriculogram. Ergonovine stimulation was not performed. The patient was discharged home on calcium entry blockers and nitrates. Exercise stress test two weeks after discharge was negative for ischemia. Induction of anesthesia triggering coronary spasm has been reported rarely, and to our knowledge never in the presence of angiographically normal coronary anatomy. Coronary vasospasm with typical EKG changes--namely, ST elevation and ventricular arrhythmias--has to be included as a possible complication of general anesthesia. Recognition of this syndrome allows prompt treatment and prevention of future episodes.
Anesthesia, General↗
Teaching field potentials: a microcomputer simulation of the nerve action potential in a bidimensional conductor.
A computer simulation of the extracellular field potential recording of nerve activity is presented. An experimental setup composed of an oscilloscope, a nerve, a conductive surface, and a recording electrode is graphically simulated. The user may study the influence of the position of the recording electrode and of certain nerve properties (membrane potential, velocity of conduction and action potential duration), on the action potential shape. The different waves which constitute the action potential may be analyzed and their peak values plotted as a function of the independent variable (e.g. electrode distance from the nerve). Three-dimensional plots of a set of action potentials as a function of the independent variable may also be obtained. The stimulation allows the user to study the basic factors which determine the configuration of an extracellularly recorded compound nerve action potential.
Action Potentials↗