Nose to back: compatibility of nasal chondrocytes with environmental conditions mimicking a degenerated intervertebral disc.

Nasal chondrocytes (NCs) have gained increased recognition for cartilage tissue regeneration. To assess NCs as a source for cell therapy treatment of intervertebral disc (IVD) degeneration, tissue-forming properties of NCs under physiological conditions mimicking the degenerated IVD were compared to those of mesenchymal stromal cells (MSCs) and articular chondrocytes (ACs), two cell sources presently used in clinical trials. Cells were cultured in a combination of low glucose, hypoxia, acidity and inflammation for 28 d. Depending on the conditions, cells were either cultured in the absence of instructive growth factors or underwent chondrogenic instructional priming by addition of transforming growth factor ß1 (TGFß1) for the first 7 d. Histology, immunohistochemistry, biochemistry, enzyme-linked immunosorbent assay (ELISA) and quantitative real-time reverse transcriptase-polymerase chain reaction (qRT-PCR) analyses demonstrated limited cell maintenance and accumulation of cartilaginous extracellular matrix for MSCs in IVD conditions. ACs maintained a steady accumulation of glycosaminoglycans (GAGs) throughout all non-acidic conditions, with and without priming, but could not synthesise type II collagen (Col2). NCs accumulated both GAGs and Col2 in all non-acidic conditions, independent of priming, whereas MSCs strongly diminished their GAG and Col2 accumulation in an inflamed environment. Supplementation with inflammatory cytokines or an acidic environment affected NCs to a lower extent than ACs or MSCs. The data, overall indicating that in an inflamed IVD environment NCs were superior to ACs and MSCs, encourage further assessment of NCs for treatment of degenerative disc disease.

Identification of metabolites of [1,2,3-(13)C]Propargyl alcohol in rat urine by (13)C NMR and mass spectrometry.

Little is known about the metabolism of acetylenic (C&tbd1;C) compounds commonly used in the formulation of pesticides. To better understand the in vivo reactivity of this bond, we examined the metabolism of propargyl alcohol (PA), 2-propyn-1-ol, used extensively in the chemical industry. [1,2,3-(13)C, 2,3-(14)C]PA was administered orally to male Sprague-Dawley rats. Approximately 56% of the dose was excreted in urine by 96 h. Major metabolites were characterized, directly, in the whole urine by one- and two-dimensional (13)C NMR. To determine the complete structures of metabolites of PA, rat urine was also subjected to TLC followed by purification of separated TLC bands on HPLC. The purified metabolites were identified by (13)C NMR and mass spectrometry and by comparison with available synthetic standards. The proposed metabolic pathway involves oxidation of propargyl alcohol to 2-propynoic acid and further detoxification via glutathione conjugation to yield as final products: 3, 3-bis[(2-(acetylamino)-2-carboxyethyl)thio]-1-propanol, 3-(carboxymethylthio)-2-propenoic acid, 3-(methylsulfinyl)-2-(methylthio)-2-propenoic acid, 3-[[2-(acetylamino)-2-carboxyethyl]thio]-3-[(2-amino-2-carboxyethyl)t hio]-1-propanol and 3-[[2-(acetylamino)-2-carboxyethyl]sulfinyl]-3-[2-(acetylamino)-2-car boxyethyl]thio]-1-propanol. These unique metabolites have not been reported previously and represent the first example of multiple glutathione additions to the carbon-carbon triple bond.

Phenobarbital tolerance and physical dependence: chronically equivalent dosing model.

A rat model of phenobarbital tolerance and physical dependence has been developed based on the 'maximally tolerable, chronically equivalent' dosing paradigm. Sodium phenobarbital was administered orally twice daily for 35 days in individually adjusted doses to achieve mean daily peak CNS depression culminating in severe ataxia. Dose to dose continuity of CNS depression was maintained throughout treatment. At the time of dosing rats were mildly ataxic. Following abrupt termination of chronic treatment, an abstinence syndrome characterized by CNS hyperexcitability was observed, which demonstrates physical dependence. Signs, which included motor, autonomic, and behavioral manifestations, appeared from 12-24 h and animals recovered by 12 days. Although tolerance development was nearly complete on day 10 of treatment, the abstinence syndrome observed was more severe following 35 than after 10 days of chronic treatment. Characteristics of tolerance and physical dependence are similar to those described for other species including humans.