Biomedical subjects

Kellen Brunaldi

Publications and source records attributed to Kellen Brunaldi.

3 recordsLinked to original sources

PubMed2005

Neurotoxic activity induced by a haemolytic substance in the extract of the marine sponge Geodia corticostylifera.

In our search for marine bioactive compounds we chose a Brazilian Coast sponge, Geodia corticostylifera (Demospongiae), whose extracts showed previously antibacterial and antifungal activities. In the present work we studied the following toxic properties of G. corticostylifera extract: neurotoxic (in mouse neuromuscular junction); mouse acute toxicity (IP) and haemolytic (against mouse and frog erythrocytes). Insertion of ionic channels in planar lipid bilayers in presence of a haemolytic purified fraction of the extract was observed. The toxic activities of G. corticostylifera crude extract are related to the formation of ionic pores in the cell membrane, which induce the release of haemoglobin from erythrocytes, and depolarization of nerve and muscle membranes. These last physiological effects cause the blockade of the diaphragm contractions, leading to death through respiratory arrest.

Animals↗

PubMed2005

Chewing over physiology integration.

An important challenge for both students and teachers of physiology is to integrate the different areas in which physiological knowledge is didactically divided. In developing countries, such an issue is even more demanding, because budget restrictions often affect the physiology program with laboratory classes being the first on the list when it comes to cuts in expenses. With the aim of addressing this kind of problem, the graduate students of our department organized a physiology summer course offered to undergraduate students. The objective was to present the different physiological systems in an integrated fashion. The strategy pursued was to plan laboratory classes whose experimental results were the basis for the relevant theoretical discussions. The subject we developed to illustrate physiology integration was the study of factors influencing salivary secretion.

Amylases↗

PubMed2004

Fatty acid flip-flop and proton transport determined by short-circuit current in planar bilayers.

The effect of palmitic acid (PA) and oleic acid (OA) on electrical parameters of planar membranes was studied. We found a substantial difference between the effects of PA and OA on proton transfer. PA induced a small increase in conductance, requiring a new technique for estimating proton-mediated currents across low-conductance planar bilayers in which an electrometer is used to measure the transmembrane current under virtual short circuit (SCC). Open-circuit voltage and SCC were used to determine proton and leak conductances. OA caused a marked increase in membrane conductance, allowing the use of a voltage-clamp technique. From SCC data, we were able to estimate the flip-flop rate constants for palmitate (1 x 10(-6) s(-1)) and oleate (49 x 10(-6) s(-1)) anions. Cholesterol, included in the membrane-forming solution, decreased importantly the leak conductance both in membranes unmodified by FA and in membranes modified by PA added to the bath.

Biochemical Phenomena↗