PubMed Health⌕ Search

Biomedical subjects

R Barraco

Publications and source records attributed to R Barraco.

8 recordsLinked to original sources
PubMed2006

Analysis of the human a-wave ERG component.

The a-wave is one of the main issues of research in the field of ocular electrophysiology, since it is strictly connected with early photoreceptoral activities. The present study proposes mathematical methods that analyse this component in human subjects, and supports experimental evidence relating to possible correlations among the responses of photoreceptoral units under a light stimulus. The investigation is organized in two parts: the first part concerns the onset and the initial slope, up to the first minimum (about 10-15 ms), the second part deals with the main portion of the wave, up to about 30 ms. In both cases, the a-waves, recorded at various levels of luminance, have been fitted with a set of appropriate functions representing possible models of physiological behaviour which would take place in the early stages of phototransduction. The statistical nature of the underlying processes is also discussed. The results indicate that correlations occur in the early stages, whereas random processes are set up later.

Algorithms↗
PubMed1992

An atlas of the rat subpostremal nucleus tractus solitarius.

The nucleus tractus solitarius (NTS) in the dorsal medulla is the principal visceral sensory relay nucleus in the brain. In the rat, numerous lines of evidence indicate that the caudal NTS at the level of the area postrema serves as a major integrating site for coordinating cardiorespiratory reflexes and viscerobehavioral responses. This region of the caudal NTS not only exhibits high densities of binding sites for an impressive array of transmitters and modulators but microinjections of many of these same neuroactive substances into the rat subpostremal NTS elicit pronounced cardiorespiratory and visceral response patterns. This report provides an abbreviated atlas of the rat subpostremal NTS consisting of a series of transverse, sagittal, and horizontal plates. Photomicrographs, together with their corresponding schematic drawings, are provided for the serial sections generated from each reference plane.

Animals↗
PubMed1984

Organic calcium channel blockers enhance [3H]purine release from rat brain cortical synaptosomes.

The release of [3H]purines was investigated in a crude mitochondrial fraction (P2 fraction) from rat brain cortex pre-loaded with [3H]adenosine for 30 sec at 37 degrees C in vitro. Potassium, veratridine and glutamate were used as depolarizing agents to evoke the release of [3H]purines. Ca2+ removal, the addition of EGTA, and treatment with organic or inorganic Ca2+ antagonists did not inhibit [3H]purine release in this preparation. On the other hand, Ca2+ removal and the addition of EGTA greatly enhanced 3H-purine release induced by glutamate. D-600 and diltiazem enhanced K+-evoked [3H]purine release, and nifedipine increased veratridine evoked [3H]purine release indicating that either these Ca2+ antagonists have different sites of action, or that K+ and veratridine may release [3H]purine from different metabolic pools. Organic Ca2+ antagonists failed to enhance the [3H]purine release evoked by glutamate, further supporting the notion that various depolarizing agents may release [3H]purines from different cellular compartments.

Adenosine↗
PubMed1977

Effect of antibiotics on retention of visual discrimination training and on protein synthesis in the pigeon.

Forty-three pigeons were trained for one day on a visual discrimination (horizontal vs. vertical stripes) and then immediately injected with either puromycin (PM), cycloheximide (CXM), control saline, or combined PM and CXM solution. PM produced a marked amnesic effect, CXM a weaker effect. PM injected animals (but not CXM's) also took significantly more than 1 day longer than controls to reach criterion levels, indicating an effect on continued acquisition of the discrimination beyond the amnesia for Day 1. Combination with CXM did not attenuate the PM effects. Protein inhibition profiles showed maximum PM activity of 90% inhibition, whereas CXM's maximum was 98% and was distributed more widely throughout different brain regions. In a second experiment, PM (N = 8), CXM (N = 8) or saline (N = 8) were again injected immediately after training, but the S+ was reversed on all postinjection training trials. In this case, PM animals were superior in percentage of S+ pecks on Day 2 to controls and CXM's. Further, the continued acquisition deficit was absent in the PM group, indicating that this effect is highly specific to those behavioral circuits active at the time of injection.

Animals↗