Biomedical subjects

V Trembovler

Publications and source records attributed to V Trembovler.

21 records · Page 2Linked to original sources

PubMed1993

Cytolysins increase intracellular calcium and induce eicosanoids release by pheochromocytoma PC12 cell cultures.

Cytolysins are the most commonly occurring toxins among bacteria, plants, and animals. By distributing cell membrane, they impair ionic permeability, leading to cell death. In an attempt to investigate cytolysin action on catecholaminergic neurons, we have treated pheochromocytoma cell cultures with Streptolysin S, Staphylococcus aureus alpha and delta, Stoichatus, Parcelsin, and cobra direct lytic factor. To measure neurotoxicity, PC12 cultures were loaded with 51Cr and exposed for 1 hr at 37 degrees C to different concentrations of cytolysins. Cytotoxic dose-response curves have been generated resulting in CD50 (cytotoxic dose 50%) in the range of 1-50 micrograms toxin/culture. Using subcytotoxic concentrations of cytolysins (which are of clinical relevance), changes on intracellular calcium were measured by Fura-2 fluorescence technique. Addition of either Stoichatus toxin and tetanolysin or streptococcus and staphylococcus cytolysins to PC12 cells caused rapidly or gradually a progressive increase in [Ca2+]i, respectively. Under similar conditions, samples of PC12 culture medium were assayed for 3H-arachidonic acid released and by radioimmunoassay for the content of PGE2 (prostaglandin), TXB2 (stable metabolite of thromboxane), and 5-HETE (hydroxy acid lipoxygenase product). PLA2 was activated 4.5-6.0-fold and the levels of all three eicosanoids were increased by 2.5-9-fold (PGE2), 4-6-fold (TXB2), and over 100-fold (5-HETE) by Stoichatus and Parcelsin cytolysins. Upon treatment with Streptolysin S and staphylococcus delta toxins PLA2 (phospholipase A2) was slightly activated (1.5-fold) and the levels of PGE2 and TXB2 increased 1.3-2.0-fold and that of 5-HETE up to 30-fold.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1993

A tissue culture ischemic device to study eicosanoid release by pheochromocytoma PC12 cultures.

In an attempt to search for neuronal models to investigate the molecular pharmacology of central nervous system ischemia, we have focused on PC12 pheochromocytoma cultures which are now popular in neuroscience research. These chromaffinergic transformed cells, originary from the adrenal medulla, synthesize and release catecholamines and, upon treatment with nerve growth factor (NGF), differentiate to a sympathetic phenotype expressing neurites and excitability. To measure eicosanoid production, undifferentiated or NGF-treated PC12 cultures have been exposed for 1 h to a mixture of N2/CO2 (95:5%), resulting in hypoxia (5 +/- 1% O2), followed by 1 h reoxygenation (21% O2) using a special ischemic device. Hypoxia, up to 2 h, was not followed by significant cytotoxicity or significant production of prostaglandin PGE2. However, upon reoxygenation, a specific release of PGE2 (2-3 fold over control) was measured. A similar PGE2-enhanced release could be induced by 'chemical hypoxia' using 2-deoxyglucose and oligomycin to reduce cellular adenosine triphosphate (ATP). Anoxia (0.1-1% O2, 1 h) achieved by a reduction of culture incubation volume and the reduction in ATP level have been found as critical parameters leading to PC12 cells cytotoxicity. These results emphasize the simplicity and applicability of the tissue culture ischemic device proposed to investigate hypoxia and ischemia at a cellular level.

Adrenal Gland Neoplasms↗

PubMed1992

Changes in brain polyamine levels following head injury.

The changes in polyamines levels in the brain after closed head injury were studied in rats. At 1 and 15 min, 24 and 48 h after closed head injury cortical tissue from the site of injury, from the contralateral region, and from remote areas were taken. The levels of the diamine putrescine and the polyamines spermine and spermidine were assayed by thin layer liquid chromatography of their dansyl derivatives. Head injury induced a significant increase in putrescine at 48 h at the site of injury and in the frontal lobe of the injured hemisphere, respectively. In the contralateral hemisphere only minor changes in putrescine were found. Spermine and spermidine showed minor changes at that time course. We have previously shown that at 24-48 h after injury, severe edema is found at the site injury. In order to study the role of putrescine in edema formation in this model we treated the traumatized rats with alpha-difluoromethyl-ornithine (DFMO), an inhibitor of ornithine-decarboxylase, the rate limiting enzyme in putrescine biosynthesis. This drug did not affect the level of edema 4 or 48 h after injury although it abolished the increase in putrescine. The effect of DFMO on blood-brain barrier function was studied, using Evans blue extravasation, at the early post-traumatic period (15 min-4 h), where a massive amount of dye is taken up by traumatized brain. No changes in the amount of dye extracted was found after DFMO treatment. On the other hand, DFMO had a beneficial effect on the neurological outcome, as evaluated by a set of clinical criteria.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗