Analytical strategies to confirm Scotch whisky authenticity. Part II: Mobile brand authentication.

Whilst the authentication of Scotch whisky brands using laboratory based gas chromatography is well established, there is a need for authentication methods for use under field test conditions. The UV/visible absorbance spectra of specific brands of Scotch whisky were found to produce consistent absorbance ranges which allowed the development of a faster, cheaper and more mobile test method. Test samples with spectra outside the acceptable ranges for genuine reference samples were therefore deemed suspect, enabling their authenticity to be later confirmed in the laboratory by GC. This novel application allowed brand authenticity analyses to be undertaken at remote sites where gas chromatography was unavailable and has also allowed the introduction of field testing using a small portable hand held spectrophotometer.

The adhesion of anti-CD3-activated mouse T cells to syngeneic colon adenocarcinoma cells is differentially regulated by protein tyrosine kinase-, protein kinase C-, and cAMP-dependent pathways in the effector cell.

The adhesion of anti-CD3-activated mouse T cells (AK-T cells) to syngeneic colon adenocarcinoma (MCA-38) cells is mediated principally through the integrin VLA-4 (alpha4beta1). We investigated the signalling pathways through which this adhesive interaction might be regulated. The protein tyrosine kinase inhibitors genistein and methyl 2,5-dihydroxycinnamate (MDHC) markedly inhibited the adhesion of AK-T cells to MCA-38 cells. Furthermore, pretreatment of the AK-T cells alone (but not the MCA-38 targets) with MDHC inhibited adhesion to a comparable extent as when MDHC was present during the assay. Calphostin C, an inhibitor of protein kinase C, also inhibited the adhesion of AK-T cells to MCA-38 monolayers. However, the phosphatidylinositol 3-kinase inhibitor wortmannin failed to alter AK-T cell adhesion to MCA-38 tumour cells. Inhibition of protein kinase A with the Rp diastereomer of adenosine cyclic 3',5'-phosphorothioate had no effect on adhesion, but the adenylyl cyclase activator forskolin and the cell-permeable cAMP analogues 8-Br-cAMP and dibutyryl-cAMP significantly suppressed adhesion. Pretreatment of AK-T cells alone with forskolin also inhibited adhesion. The adhesion of AK-T cells to MCA-38 tumour targets is therefore promoted by protein tyrosine kinases and protein kinase C, but inhibited by cAMP-dependent pathways, and the predominant location of the regulatory pathways is within the effector cell.

Adenosine inhibits the adhesion of anti-CD3-activated killer lymphocytes to adenocarcinoma cells through an A3 receptor.

We have investigated the hypothesis that adenosine, a purine nucleoside produced within hypoxic regions of solid tumors, may interfere with the recognition of tumor cells by cytolytic effector cells of the immune system. We measured the adhesion of murine spleen-derived anti-CD3-activated killer (AK) lymphocytes to syngeneic MCA-38 colon adenocarcinoma cells in a model system. Adenosine, in the presence of the adenosine deaminase inhibitor coformycin to prevent the breakdown of adenosine, inhibited adhesion by up to 60%. The inhibitory effect of adenosine was exerted on the AK cells and not on the MCA-38 targets. The response to adenosine was generated at the cell surface, since the inhibition of adhesion was not abrogated by S-(4-nitrobenzyl)-6-thioinosine or dipyridamole, which block adenosine uptake. The inhibition of adhesion due to adenosine was not blocked by either the A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine or the A2 receptor antagonist 3,7-dimethyl-1-propargylxanthine. This suggested that a non-A1, A2 receptor might be involved. The relative order of potencies of adenosine and common analogues was: 5'-N-ethylcarboxamidoadenosine = adenosine = (R)-phenylisopropyladenosine > N6-cyclopentyladenosine > 2-chloro-N6-cyclopentyladenosine = 2-p-(2- carboxyethyl)phenethylamino-5'-N-ethyl-carboxamidoadenosine. This agonist potency profile was again inconsistent with either the A1 or the A2 receptor subtype but indicated that the recently described A3 receptor subtype might be responsible for the inhibition of adhesion. Consistent with this suggestion, aminophenylethyladenosine, an adenosine analogue that binds with high affinity to A3 receptors, inhibited the adhesion of AK cells to MCA-38 tumor cells with high potency (50% inhibitory concentration approximately 1 nM). Adenosine, therefore, interferes with the AK cell recognition of colorectal tumor targets by acting through an A3 receptor on the effector cells. We suggest that this mechanism of immunosuppression, secondary to tissue hypoxia, may be important in the resistance of colorectal and other solid cancers to immunotherapy.