Extractionless method for the simultaneous high-performance liquid chromatographic determination of urinary caffeine metabolites for N-acetyltransferase 2, cytochrome P450 1A2 and xanthine oxidase activity assessment

Urinary metabolic ratios of caffeine are used in humans to assess the enzymatic activities of cytochrome P450 isoenzyme 1A2 (CYP1A2), xanthine oxidase (XO) and for phenotyping individuals for the bimodal N-acetyltransferase 2 (NAT2), all of them involved in the activation or detoxification of various xenobiotic compounds. Most reported analytical procedures for the measurement of the urinary metabolites of caffeine include a liquid–liquid extraction of urine samples prior to their analysis by reversed-phase HPLC. At neutral to basic pH however, 5-acetylamino-6-formylamino-3-methyluracil (AFMU), a metabolite of caffeine, spontaneously decomposes to 5-acetylamino-6-amino-3-methyluracil (AAMU). Since AAMU is not extracted in most organic solvents, the extent of AFMU decomposition cannot be precisely assessed. Although the decomposition reaction can be minimized by immediate acidification of the urine, accurate results can only be obtained when both AAMU and AFMU are monitored, or alternatively, if AAMU is measured after complete transformation of AFMU into AAMU in basic conditions. We report a liquid chromatographic method for the simultaneous quantitative analysis of the five urinary metabolites of caffeine used for the CYP1A2, XO and NAT2 phenotyping studies: AAMU, AFMU, 1-methylxanthine, 1-methyluric acid and 1,7-dimethyluric acid. These metabolites are satisfactory separated from all other known caffeine metabolites as well as endogenous urinary constituents. Sample treatment does not require any liquid–liquid extraction procedure. Urine samples are diluted and centrifuged before being injected (10 μl) onto a YMC-Pack Polyamine II (250×4.6 mm) column. A step-wise gradient elution program is applied using acetonitrile–0.75% (v/v) formic acid: (91:9) at 0 min→(75:25) at 25 min→(65:35) at 35 min→(65:35) at 45 min, followed by a re-equilibration step to the initial solvent composition. The flow-rate is 1.0 ml/min and the separations are monitored by UV absorbance at 260 and 280 nm. The procedure described here represents a substantial improvement over previous methods: a single analysis and a minimal urine sample treatment enables the simultaneous quantitation of five caffeine metabolites, notably AFMU and AAMU, used for the determination of CYP450 1A2, XO and NAT2 enzyme activity. Importantly enough, phenotyping individuals for the bimodal NAT2 is made possible without the uncertainty associated with the deformylation of AFMU, which is likely to happen at all steps prior to the analysis, during sample storage and even in the bladder of the subjects.     

A phenome-guided drug repositioning through a latent variable model

Background

The phenome represents a distinct set of information in the human population. It has been explored particularly in its relationship with the genome to identify correlations for diseases. The phenome has been also explored for drug repositioning with efforts focusing on the search space for the most similar candidate drugs. For a comprehensive analysis of the phenome, we assumed that all phenotypes (indications and side effects) were inter-connected with a probabilistic distribution and this characteristic may offer an opportunity to identify new therapeutic indications for a given drug. Correspondingly, we employed Latent Dirichlet Allocation (LDA), which introduces latent variables (topics) to govern the phenome distribution.

Results

We developed our model on the phenome information in Side Effect Resource (SIDER). We first developed a LDA model optimized based on its recovery potential through perturbing the drug-phenotype matrix for each of the drug-indication pairs where each drug-indication relationship was switched to “unknown” one at the time and then recovered based on the remaining drug-phenotype pairs. Of the probabilistically significant pairs, 70% was successfully recovered. Next, we applied the model on the whole phenome to narrow down repositioning candidates and suggest alternative indications. We were able to retrieve approved indications of 6 drugs whose indications were not listed in SIDER. For 908 drugs that were present with their indication information, our model suggested alternative treatment options for further investigations. Several of the suggested new uses can be supported with information from the scientific literature.

Conclusions

The results demonstrated that the phenome can be further analyzed by a generative model, which can discover probabilistic associations between drugs and therapeutic uses. In this regard, LDA serves as an enrichment tool to explore new uses of existing drugs by narrowing down the search space.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2105-15-267) contains supplementary material, which is available to authorized users.     

Antiproliferative activities of isolated flavone glycosides and fatty acids from Stachys byzantina

From the aerial parts of Stachys byzanthina C. Koch., a new flavone glycoside, was isolated for the first time in addition to known two flavone glycosides. Structures were established by conventional methods of analysis and confirmed by ¹H, ¹³C NMR and mass spectral analysis. Antiproliferative activities of isolated compounds, crude extract and fractions, fatty acids (extracts of hexane and hexane:ethyl acetate, 9:1) of aerial parts of S. byzantina were investigated against Vero (African green monkey kidney), HeLa (human uterus carcinoma) and C6 (rat brain tumor) cells in vitro and compared with 5-fluorouracil (5-FU). Antiproliferative effect of the extract, isolated flavonoids and fatty acids were tested at 100, 250, 500 and 1000 μg/mL using BrdU cell proliferation ELISA.     

The Effects of Levosimendan Exposure on Oxidant/Antioxidant Status and Trace Element Levels in the Pulmonary Artery of Rats

We investigated both the effect of levosimendan and the role of oxidant/antioxidant status and trace element levels in the pulmonary artery of rats. Fourteen male Wistar albino rats were randomly divided into two groups of seven animals each. Group 1 was not exposed to levosimendan and served as a control. Levosimendan (12 μg/kg) diluted in 10 ml 0.9 % NaCl was administered intraperitoneally to group 2. Animals of both groups were killed after 3 days, and their pulmonary arteries were harvested to determine changes in tissue oxidant/antioxidant status and trace element levels. The animals in both groups were killed 72 h after the levosimendan exposure treatment, and pulmonary arteries were harvested to determine levels of the lipid peroxidation product MDA and the antioxidant GSH as well as the decreased activity of antioxidant enzymes such as SOD, GSH-Px and CAT. It was found that MDA levels increased in pulmonary artery tissues of rats after levosimendan administration. The GSH level decreased in the pulmonary artery of rats after levosimendan treatment. Co, Mn, Fe, Cd and Pb levels were significantly higher (P < 0.001) and Mg, Zn and Cu levels significantly lower (P < 0.001) in the levosimendan group compared to the control group. These results suggest that levosimendan treatment caused an increase in free radical production and a decrease in antioxidant enzyme activity in the pulmonary artery of levosimendan-treated rats. It also caused a decrease or increase in the levels of many minerals in the pulmonary artery, which is an undesirable condition for normal pharmacological function.     

The number of CD161 positive Th17 cells are decreased in head and neck cancer patients

Background

Despite lots of research efforts, the pathology of head and neck cancer remains elusive. Accumulating evidence suggests that the innate and adaptive immunity plays an important role in HNSCC (Head and Neck Squamous Cell Carcinoma) development. Recently, a new T helper cell subset additional to the classical Th1 and Th2 cells was identified called Th17 cells, due to their secretion of IL-17. However, Th17 cells also produce additional proinflammatory cytokines and many other cytokines are involved in their differentiation and expansion. It was shown that Th17 cells play a prominent role in host defense but are also associated with the development of autoimmune diseases. The role of Th17 cells in cancer pathogenesis remains nebulous.

Methods

Th17 cells of peripheral blood, primary tumors and metastatic lymph nodes were FACS analyzed for their CD161 expression. Supernatants of the permanent HNSCC cell line BHY were used to induce Th17 cells by HNSCC tumor mileu.

Results

Here we show that Th17 cells from patients with HNSCC downregulate the Th17 cell surface receptor CD161 in peripheral blood as well as in primary tumors and especially in metastatic lymph nodes.

Conclusion

We have showed for the first time alterations of Th17 cell phenotype in HNSCC patients.     

Colchicine Modulates Oxidative Stress in Serum and Leucocytes from Remission Patients with Family Mediterranean Fever Through Regulation of Ca<Superscript>2+</Superscript> Release and the Antioxidant System

We investigated the effects of colchicine on oxidative stress and Ca²⁺ release in serum and polymorphonuclear leucocytes (PMNs) of Familial Mediterranean Fever (FMF) patients with attack, remission and unremission periods. Eighteen FMF patients and six age-matched healthy subjects in four groups were used. The first group was a control. The second group included patients with active FMF. The third and fourth groups were patients with remission and unremission, respectively. Colchicine (1.5 mg/day) was given to the third and fourth groups for 1 month. PMN cells, serum lipid peroxidation and intracellular Ca²⁺-release levels in the attack and unremission groups were higher than in those in controls, although they were lower in the remission group than in the attack group. Serum vitamin E and β-carotene concentrations were higher in the remission group than in the control and attack groups. However, PMN, serum lipid peroxidation and Ca²⁺-release levels were further increased in the unremission group compared to the attack group. Glutathione peroxidase, reduced glutathione and vitamin A values in the four groups did not change by FMF and colchicine. In conclusion, we observed that colchicine induced protective effects on oxidative stress by modulating vitamin E, β-carotene and Ca²⁺-release levels in FMF patients with a remission period.