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Biomedical subjects

D A Silva

Publications and source records attributed to D A Silva.

10 recordsLinked to original sources
PubMed1992

Continuous positive airway pressure as a promoter of laryngospasm during halothane anesthesia.

Twenty mongrel dogs were anesthetized with halothane 2.0%, 1.25%, 0.94%, and 0.63% in oxygen. Thyroarytenoid (TA) and posterior cricoarytenoid (PCA) electromyography (EMG) tracings were recorded with the animal at rest, following mechanical irritation of the glottis, and during 20 mm Hg continuous positive airway pressure (CPAP) following either airway occlusion or hyperventilation. Adductor laryngospasm was defined as continuous tonic TA EMG activity, silent PCA EMG, and vocal cord adduction. Abductor laryngospasm was defined as continuous tonic PCA EMG activity, silent TA EMG, and vocal cord abduction. Combined laryngospasm was defined as continuous tonic PCA and TA EMG activity, with variable vocal cord position. The incidence of adductor laryngospasm following mechanical irritation was 30% to 50%. The combined incidence of laryngospasm during application of CPAP following airway occlusion or hyperventilation was 25% to 50%, and differed from the incidence of irritation-induced adductor laryngospasm by 5% or less at the same anesthetic level. Continuous positive airway pressure appears to be a stimulant of laryngeal muscle spasm comparable to mechanical irritation of the glottis.

Airway Obstruction↗
PubMed1990

A neutral lipophilic technetium-99m complex for regional cerebral blood flow imaging.

Technetium-99m-DMG-2MP (Chloro[bis[2,3-butanedionedioxime(1-)-0][2,3- butanedionedioximato (2-)-N,N',N'',N''',N'''',N'''''] (2-methylpropyl borato (2-))technetium]), also known as SQ 32097 is a member of a family of neutral lipophilic compounds generally known as boronic acid adducts of technetium dioxime complexes (BATOs). After i.v. administration, the concentration of [99mTc]DMG-2MP in various regions of the brain appears to be proportional to blood flow. In rats, 1.1% ID was in the brain at 5 min postinjection when the blood contained less than 3% ID. Over 24 hr excretion was 59% in the feces and 23% in the urine. The activity in monkey brain at 5 min was 2.8% ID and it cleared with a t1/2 of 86 min. Autoradiographs of monkey brain sections showed excellent regional detail with a gray/white ratio of 3.6 at 10 min. The distribution of [99mTc]DMG-2MP in the monkey brain corresponds to the known cytoarchitectural pattern of cerebral glucose metabolism. The properties of [99mTc]DMG-2MP make it a potentially useful agent for cerebral perfusion imaging in man.

Animals↗
PubMed1979

A technique for separating endogenous from exogenous human cortical potentials.

In a temporal discrimination paradigm, if signal duration is the stimulus dimension to be discriminated, the moment of subject's decision can be manipulated by varying the duration of the target stimulus. As stimulus duration is lengthened, task-contingent potentials related to the decision process can be separated from those evoked by stimulus onset. Analysis of individual evoked responses indicates that 3 task-contingent components, occurring at 220, 300 and 340 msec are precisely time-locked to the moment of decision.

Acoustic Stimulation↗
PubMed1978

Multihandicapped children's preferences for pure tones and speech stimuli as a method of assessing auditory capabilities.

Residual hearing capabilities of nine severely and profoundly retarded multihandicapped deaf-blind children were determined with an operant procedure that allowed the children to respond by making a selection between two alternative responses. One response option resulted in the presentation of auditory reinforcement (pure tones and speech stimuli of various frequencies); the other option resulted in no reinforcement. Levels of the sound intensity were varied systematically to obtain a "threshold" for selective responding. Each of the severely damaged "untestable" children made numerous meaningful responses throughout the testing sessions, thereby revealing the levels of intensity that could be heard and those that were not high enough to elicit preferential responding. The children responded comparably in conditions employing pure tones and speech. The responses of most of the children were comparable across frequency conditions, although some of the children's records show selective responding at lower levels of intensity for certain frequencies than for others. We also found that varying the level of intensity of the stimuli not only affected the children's selective behavior, but also their time on task measures and their individual patterns of responding.

Acoustic Stimulation↗