Contribution of inorganic and organic ions to conductivity changes during lactic acid fermentation

On-line estimation of lactic acid produced by Lactobacillus casei in a pilot scale reactor coupled with a microfiltration module is performed by measuring the conductance on the permeate effluent. Non-interference by other ions (inorganic and organic) present in the medium has been verified. This method is found more reliable that the estimation of lactate concentration from the amount of alkaline solution supplied for the pH control.     

Contribution of organic and inorganic osmolytes to volume regulation in rat brain cells in culture

In this work we examined the time course and the amount released, by hyposmolarity, for the most abundant free amino acids (FAA) in rat brain cortex astrocytes and neurons in culture. The aim was to evaluate their contribution to the process of cell volume regulation. Taurine, glutamate, andd-aspartate in the two types of cells, -alanine in astrocytes and GABA in neurons were promptly released by hyposmolarity, reaching a maximum within 1–2 min. after an osmolarity change. A substantial amount of the intracellular pool of these amino acids was mobilized in response to hyposmolarity. The amount released in media with osmolarity reduced from 300 mOsm to 150 mOsm or 210 mOsm, represented 50%–65% and 13%–31%, respectively, of the total amino acid content in cells. In both astrocytes and neurons, the efflux of glutamine and alanine was higher under isosmotic conditions and increased only marginally during hyposmotic conditions.⁸⁶Rb⁺, used as tracer for K⁺, was released from astrocytes, 30% and 11%, respectively, in hyposmotic media of 150 mOsm or 210 mOsm but was not transported in neurons. From these results it was calculated that FAA contribute 54% and inorganic ions 46% to the process of volume regulation in astrocytes exposed to a 150 mOsm hyposmotic medium. This contribution was 55% for FAA and 45% for K⁺ and Cl^– in cells exposed to 210 mOsm hyposmotic solutions. These results indicate that the contribution of FAA to the process of cell volume regulation is higher in astrocytes than in other cell types including renal and blood cells.Special issue dedicated to Dr. Claude Baxter.     

Chemiluminescent determination of choline in cerebrospinal fluid and red blood cells

The concentration of choline in the cerebrospinal fluid (CSF) of patients affected by primary dementia and in red blood cells (RBC) of depressed patients before and after treatment with lithium salts was determined using a chemiluminescent assay. The mean CSF concentration of choline was found to be 60 pmoles/ml (SD = 20 pmoles/ml) and this was lower than values obtained previously by spectrophotometric-colorimetric methods. Mean RBC choline concentrations before and after therapy with lithium salts were 20 nmoles/ml (SD = 16 nmoles/ml and 328 nmoles/ml (SD = 206 nmoles/l) respectively and these are similar to those reported previously (obtained by chemiluminescent and non-chemiluminescent methods).     

Contribution to central nervous system tumor diagnosis by means of cytocentrifuged cerebrospinal fluid]

The cytocentrifugation of the liquor cerebrospinalis provides a useful diagnostic tool to differentiate benign from malign diseases of the central nervous system. The method is illustrated with liquor analyses in the field of pediatric oncology: medulloblastoma, leptomeninx sarcoma, plexuspapilloma, astrocytoma, Abt-Letterer-Siwe, ALL, reticulum cell sarcoma, Ewing sarcoma, retinoblastoma. The speed and ease of the processing, the highest possible cellular yield and the good preservation of the cellular characteristics are great advantages of this new method.