Testing competing path models linking the biochemical variables in red blood cells from Li+-treated bipolar patients

Development of a bioreactor system for cytotoxic evaluation of pharmacological compounds in living cells using NMR spectroscopy

INTRODUCTION

The evaluation of drug's cytotoxicity is a crucial step in the development of new pharmacological compounds. ³¹P NMR can be a tool for toxicological screening, as it enables the study of drugs' cytotoxicity and their effect on cell energy metabolism in a real-time, in a non- invasive and non-destructive way. This paper details a step-by-step protocol to implement a bioreactor system able to maintain cell viability during NMR acquisitions, at high cell densities and for several hours, enabling toxicological evaluation of pharmacological compounds in living cells.

METHOD

HeLa cells were immobilized in agarose gel threads and continuously perfused with oxygenated medium inside a 5 mm NMR tube. Signals corresponding to intracellular high-energy phosphorous compounds were continuously monitored by ³¹P NMR to assess cell energy levels, intracellular pH and intracellular free Mg²⁺ concentrations ([Mg²⁺]_f) under control and in the presence of two different cytotoxic drugs, calix-NH₂ or 5-fluorouracil (5-FU).

RESULTS

The bioreactor system was effective in maintaining cell energy levels as well as intracellular pH and [Mg²⁺]_f along time, with a good ³¹P NMR signal to noise ratio. Calix-NH₂ and 5-FU decreased cell energy levels by 35% and 39%, respectively, with a negligible increase in intracellular [Mg²⁺]_f, and without affecting intracellular pH.

DISCUSSION

The immobilization and perfusion system here detailed, along with ³¹P NMR, is useful in toxicological evaluation of new pharmacological compounds, enabling the continuous assessment of drugs' effect on energy levels, intracellular pH and [Mg²⁺]_f in intact cells, for several hours without compromising cell viability.

Cerebellar syndrome in a patient with pneumonia under lithium treatment: A case report

We report the case of a 31-year-old man with bipolar disorder who was on a combination therapy of lithium, lamotrigine and escitalopram. Serum lithium level was within therapeutic range. Cerebellar symptoms such as dysarthria, ataxia, and dyskinesia developed in the patient following the pneumonia. Cerebellar syndrome was most likely due to lithium neurotoxicity, which was associated with additional factors such as acute febrile pneumonia, fever and hyponatremia. The reported case suggests that infections may increase the risk of cerebellar toxicity of lithium, even in the therapeutic doses.

Biomedical applications of 7Li NMR

The biomedical applications of 7Li MRS and MRI have been progressing slowly. The interest derives primarily from the clinical use of Li to treat bipolar disorder. One area of concern is the nature of ionic transport and binding, so as to elucidate the mechanism(s) of therapeutic action and toxicity. Another is the development of a non-invasive, in vivo analytical tool to measure brain Li concentration and environment in humans, both as an adjunct to treatment and as a mechanistic probe. Here we review the most recent progress toward these goals.