Development and characterization of a three-dimensional co-culture model of tumor T cell infiltration.

Tumor growth and metastasis entangle the alteration and recruitment of non-malignant cells to the primary tumor, among them immune cells, constituting the tumor microenvironment (TME). Communication between tumor cells and their stroma has been shown as a fundamental driving force of the tumoral process. A great deal of effort has been focused on depicting their specific interactions and crosstalk. However, most research has been carried out in 2D conventional cultures that alter cell morphology and intracellular signaling processes. Considering these premises, we have developed a 3D cell co-culture model to mimic T cell infiltration into the tumor mass and explore tumor-immune cells interactions in the TME. Expression of specific cell markers and assessment of cell proliferation were carried out to characterize the proposed 3D co-culture model. Additionally, the study and profiling of the secretome revealed a subset of particular cancer-related inflammation proteins prompted upon 3D cultivation of tumor cells in presence of lymphocytes, pointing out an intercellular communication. Altogether, these results suggest that our 3D cell co-culture model can be a useful tool to identify and study critical factors mediating the crosstalk between tumor and immune cells in the TME. Finally, the potential of this model as a drug-screening platform has been explored using docetaxel as a model antitumoral compound.

Rapid and simple determination of clenbuterol residues in retina by high-performance liquid chromatography with ultraviolet detection.

A new method for the determination of clenbuterol by reversed-phase HPLC with UV detection has been developed. Clenbuterol was eluted on a C8 column (250 x 4.6 mm I.D), using an isocratic eluent consisting of an acetonitrile -0.02 M phosphate buffer (25:75, v/v) adjusted to pH 2.8 with phosphoric acid. The method was linear from 2.5 to 50 ng injected. The detection limit was established to be 0.5 ng (signal/background ratio: 3), and the quantification limit was 2.5 ng. With the proposed method, we got a simple and rapid detection of clenbuterol in the retina, part of the animal where the biggest amount of clenbuterol is accumulated and where it remains for the longest time after any treatment.

Susceptibilities of Listeria species isolated from food to nine antimicrobial agents.

The agar dilution method was used to determine the activities of gentamicin, erythromycin, streptomycin, chloramphenicol, ampicillin, sulfamethazine, cephalothin, penicillin G, and tetracycline against 73 strains belonging to the genus Listeria (L. innocua, L. seeligeri, and L. monocytogenes). All strains were isolated from raw milk, cheese, the dairy processing plant, poultry, and the poultry slaughterhouse. Gentamicin, ampicillin, and erythromycin, of which the MICs for 90% of the strains tested for all three species were < or = 5.96 micrograms/ml, were found to be the most active agents studied. Most of the L. innocua strains isolated from poultry and the poultry slaughterhouse were resistant to tetracycline.

Effects of frozen storage on the recovery of clenbuterol from urine samples for official control.

The effects of storage under frozen conditions on clenbuterol recovery from spiked calf urine samples were studied. Urine samples contaminated with 10 micro g l(-1) clenbuterol and frozen at -15 degrees C were analysed every 15 days over 6 months. A single frozen contaminated urine sample was also thawed every 15 days over 3 months for the analysis of 10-ml aliquots, after which the remaining portion was frozen again (-15 degrees C). The presence of clenbuterol was determined by GC-MS. A gradual decline in clenbuterol recovery was observed from the first to the 180th day. It was only possible to recover 1.74 +/- 0.06 micro g l(-1) (17%) clenbuterol on the 180th day in samples stored at -15 degrees C. Likewise, clenbuterol totally disappeared from spiked urine samples that had been successively frozen and thawed over 3 months. The results were confirmed in a study performed on 2704 calf urine samples collected on farms and analysed by HPTLC and GC-MS. Of 73 positive samples, 61 had been frozen for <10 days.