Determination of the 13C/12C Ratio of Ethanol Derived from Fruit Juices and Maple Syrup by Isotope Ratio Mass Spectrometry: Collaborative Study

A collaborative study of the carbon-13 isotope ratio mass spectrometry (13C-IRMS) method based on fermentation ethanol for detecting some sugar additions in fruit juices and maple syrup is reported. This method is complementary to the site-specific natural isotope fractionation by nuclear magnetic resonance (SNIF-NMR) method for detecting added beet sugar in the same products (AOAC Official Methods 995.17 and 2000.19), and uses the same initial steps to recover pure ethanol. The fruit juices or maple syrups are completely fermented with yeast, and the alcohol is distilled with a quantitative yield (>96%). The carbon-13 deviation (δ13C) of ethanol is then determined by IRMS. This parameter becomes less negative when exogenous sugar derived from plants exhibiting a C4 metabolism (e.g., corn or cane) is added to a juice obtained from plants exhibiting a C3 metabolism (most common fruits except pineapple) or to maple syrup. Conversely, the δ13C of ethanol becomes more negative when exogenous sugar derived from C3 plants (e.g., beet, wheat, rice) is added to pineapple products. Twelve laboratories analyzed 2 materials (orange juice and pure cane sugar) in blind duplicate and 4 sugar-adulterated materials (orange juice, maple syrup, pineapple juice, and apple juice) as Youden pairs. The precision of that method for measuring δ13C was similar to that of other methods applied to wine ethanol or extracted sugars in juices. The within-laboratory (sr) values ranged from 0.06 to 0.16‰ (r = 0.17 to 0.46‰), and the among-laboratories (sR) values ranged from 0.17 to 0.26‰ (R = 0.49 to 0.73‰). The Study Directors recommend that the method be adopted as First Action by AOAC INTERNATIONAL.

Evidence for the absence of visceral pain in C57BL6/N mice subjected to therapeutically relevant O3/O2-pneumoperitoneum

Each different gas that is used to induce a pneumoperitoneum (PP) exhibits individual effects within the peritoneal cavity. This might include adverse effects such as pain and/or inflammatory reactions. The acute effects of ozonized oxygen (O₃/O₂), a highly oxidative gas mixture, after being insufflated into the peritoneal cavity are analysed in this study. Using the abdominal constriction response ('writhing') assay of chemical nociception in C57BL6/N mice, O₃/O₂-PP was found not to be associated with visible pain responses and did not alter the c-fos expression in the spinal cord. In addition, mRNA expression levels of the pro-inflammatory cytokines, interleukin (IL)-1β and IL-6, were found unaltered in the spleen 2 h after insufflation. In conclusion, O₃/O₂-PP is free of adverse pain and does not trigger inflammatory immune responses.

Intraperitoneal oxidative stress in rabbits with papillomavirus-associated head and neck cancer induces tumoricidal immune response that is adoptively transferable

PURPOSE

How tumors evade or suppress immune surveillance is a key question in cancer research, and overcoming immune escape is a major goal for lengthening remission after cancer treatment. Here, we used the papillomavirus-associated rabbit auricular VX2 carcinoma, a model for studying human head and neck cancer, to reveal the mechanisms underlying the antitumorigenic effects of intraperitoneal oxidative stress following O3/O2-pneumoperitoneum (O3/O2-PP) treatment.

EXPERIMENTAL DESIGN

Solid auricular VX2 tumors were induced in immune-competent adult New Zealand White Rabbits. Animals were O3/O2-PP- or sham-treated, after which they underwent tumor ablation upon reaching no-go criteria. CD3(+) tumor-infiltrating lymphocytes (TIL) were evaluated by immunohistochemistry, and expression levels of 84 immune response genes were measured by quantitative real-time PCR. Adoptive transfer of peripheral blood leukocytes (PBL)-derived from animals with tumor regression-into control animals with progressing tumors was implemented to assess acquired tumor resistance functionally.

RESULTS

Auricular VX2 tumors regressing after O3/O2-PP treatment exhibited increased levels of CD3(+) TILs; they also exhibited enhanced expression of genes that encode receptors involved in pattern recognition, molecules that are required for antigen presentation and T cell activation, and inflammatory mediators. Adoptive cell transfer of PBLs from donor rabbits with regressing tumors to recipient rabbits with newly implanted VX2 carcinoma resulted in acquired tumor resistance of the host and tumor regression.

CONCLUSION

Intraperitoneal oxidative stress effectively converts the immune response against the papillomavirus-associated rabbit VX2 carcinoma from tumor permissive to tumoricidal and leads to a sustainable, adoptively transferable oncolytic immune response.

A cisplatin-resistant head and neck cancer cell line with cytoplasmic p53(mut) exhibits ATP-binding cassette transporter upregulation and high glutathione levels

PURPOSE

Head and neck squamous cell carcinoma (HNSCC) cell lines with cytoplasmically sequestered mutant p53 (p53(mut_c)) are frequently more resistant to cisplatin (CDDP) than cells with mutant but nuclear p53 (p53(mut_n)). The aim of the study was to identify underlying mechanisms implicated in CDDP resistance of HNSCC cells carrying cytoplasmic p53(mut).

METHODS

Microarray analysis, quantitative reverse transcription polymerase chain reaction, Western blot analysis and immunocytochemistry were used to identify and evaluate candidate genes involved in CDDP resistance of p53(mut_c) cells. RNAi knockdown or treatment with inhibitors together with flow cytometry-based methods was used for functional assessment of the identified candidate genes. Cellular metabolic activity was assessed with the XTT assay, and the redox capacity of cells was evaluated by measuring cellular glutathione (GSH) levels.

RESULTS

Upregulation of ABCC2 and ABCG2 transporters was observed in CDDP-resistant p53(mut_c) HNSCC cells. Furthermore, p53(mut_c) cells exhibited a pronounced side population that could be suppressed by RNAi knockdown of ABCG2 as well as treatment with the ATP-binding-cassette transporter inhibitors imatinib, MK571 and tariquidar. Metabolic activity and cellular GSH levels were higher in CDDP-resistant p53(mut_c) cells, consistent with a higher capacity to fend off cytotoxic oxidative effects such as those caused by CDDP treatment. Finally, ABCC2/G2 inhibition of HNSCC cells with MK571 markedly enhanced CDDP sensitivity of HNSCC cells.

CONCLUSIONS

The observations in this study point to a major role of p53(mut_c) in conferring a stem cell like phenotype to HNSCC cells that is associated with ABCC2/G2 overexpression, high GSH and metabolic activity levels as well as CDDP resistance.

SIVmac₂₃₉-Nef down-regulates cell surface expression of CXCR4 in tumor cells and inhibits proliferation, migration and angiogenesis

AIM

To evaluate if the lentiviral accessory protein Nef can down-regulate the C-X-C chemokine receptor type 4 (CXCR4) in tumor cells and affect tumor cell proliferation, migration and angiogenesis.

MATERIALS AND METHODS

HeLa-(ACC) cells, which according to genotype analysis are virtually identical to the cervical cancer-derived HeLa cell line, were transfected with Nef from SIV(mac239) and expression levels of cell surface CXCR4 were monitored by flow cytometry. Real-time proliferation and migration of cells was measured with the xCELLigence system or with the in vitro scratch assay. In vitro tube formation was deployed to assess the effect of Nef on angiogenesis.

RESULTS

Cell surface down-regulation of CXCR4 was observed in HeLa-(ACC) cells after Nef transfection, as well as in the monkey kidney-derived COS-7 cell line after co-transfection of CXCR4 and Nef. Proliferation, as well as migration, of Nef-transfected HeLa-(ACC) cells appeared to be significantly reduced. In vitro tube formation was markedly lowered after Nef transfection, and CXCR4 knockdown with siRNA.

CONCLUSION

SIV-Nef could serve as an interesting tool to study the biological behavior of CXCR4-expressing tumor cells and could be helpful in the discovery of new therapeutic approaches for the treatment of CXCR4-positive tumors.

Nef from SIV(mac239) decreases proliferation and migration of adenoid-cystic carcinoma cells and inhibits angiogenesis

The HIV/SIV accessory protein Nef is known to down-modulate cell surface receptors that are required for virus entry such as CD4, CCR5 and CXCR4 to block lethal viral superinfection of the infected cell. The chemokine receptor CXCR4 also plays an important role in promoting cell proliferation, metastasis and tumor angiogenesis. Therefore it was of interest to evaluate if Nef can down-regulate CXCR4 in tumor cells since this could affect these critical prognostic parameters. The CXCR4-expressing cell line ACC3 that was derived from a salivary gland adenoid cystic carcinoma (ACC) of the head and neck was transfected with Nef from SIV(mac239) and cell surface expression of the receptor was monitored by FACS analysis. Real time proliferation of cells was measured with the xCELLigence system (Roche, Mannheim, Germany). Cell migration was detected by an in vitro scratch assay. Similarly, COS-7 cells were co-transfected with CXCR4 and Nef and were treated as described for ACC3. In vitro tube formation was deployed to assess the effect of Nef on angiogenesis. siRNA was used for CXCR4 knockdown. Cell surface down-modulation of endogenous CXCR4 could be observed in ACC3 cells after Nef-transfection as well as in COS-7 cells after co-transfection of CXCR4 and Nef. Proliferation as well as migration of Nef-transfected ACC3 tumor cells appeared significantly reduced. In vitro tube formation was significantly lowered after Nef-transfection or CXCR4 knockdown with siRNA. SIV-Nef could serve as an interesting tool to study the biologic behavior of CXCR4-expressing tumors such as ACC. Deploying SIV-Nef thereby could help in the discovery of new therapeutic approaches for the treatment of ACC and other CXCR4-expressing tumors.

Potential role of P-gp for flavone-induced diminished apoptosis and increased adenoma size in the small intestine of APC(min/+) mice

APC(min/+) mice, carrying a nonsense mutation in the adenomatous polyposis coli (APC) gene, appear as a perfect model to study development or therapy of intestinal neoplasia. We tested whether the flavonoid flavone is able to affect adenoma development in APC(min/+) mice. Tumor sizes were significantly increased by flavone selectively in small intestine. This was associated with reduced cell numbers displaying cleaved caspase-3 and enhanced expression of phosphoglycoprotein (P-gp). However, according to great variability in P-gp expression in all parts of mice intestines, an association between expression of P-gp and inhibition of apoptosis was demonstrated in human Caco-2 colorectal cancer cells.

Chrysin blocks topotecan-induced apoptosis in Caco-2 cells in spite of inhibition of ABC-transporters

ATP-driven efflux pumps such as phosphoglycoprotein-170 (P-gp), multidrug-resistance-associated protein-2 (MRP-2), or breast cancer resistance protein (BCRP) play a crucial role in limiting the efficacy of tumor pharmacotherapy. Selected flavonoids have been suggested to inhibit individual efflux-transporters and to act therefore as multidrug-resistance reversing agents. In the present study it is shown that the flavonoid chrysin acts as a potent inhibitor of P-gp, MRP-2, and BCRP in Caco-2 colon carcinoma cells. As a consequence, cells accumulated higher rates of the apoptosis-inducing chemotherapeutic topotecan in the presence of chrysin, even though under these conditions the expression of the transporters was markedly increased. Interestingly, in spite of the enhanced cellular drug accumulation the topotecan-induced apoptosis, assessed according to DNA-fragmentation, chromatin condensation, and by determination of sub-G1 peaks using fluorescence-assisted-cell sorting (FACS), was potently inhibited by chrysin. Suggested transport-independent apoptosis inhibiting activities of ATP-binding cassette (ABC)-transporters, such as the inhibition of caspases, were shown to be necessary for the inhibition of topotecan-induced apoptosis and were found to be associated with stabilization of beta-catenin especially in the cytosol. Inhibition of topotecan-induced intracellular acidification, however, was proven not to prevent caspase-activation and apoptosis. In conclusion, our studies show that chrysin in spite of raising the cellular concentrations of topotecan potently inhibits the apoptosis-inducing activities of the anti-tumor drug. Inhibition of caspase-activation was identified as the underlying mechanism and is suggested to be caused by transport-independent functions of ABC-transporters.

Coast and year effect on H, O and C stable isotope ratios of Tyrrhenian and Adriatic Italian olive oils

The paper discusses the (2)H/(1)H, (18)O/(16)O and (13)C/(12)C ratios of 196 authentic Italian extra-virgin olive oils produced in 3 years on the Tyrrhenian and Adriatic coasts. The (2)H/(1)H and (18)O/(16)O ratios were linearly and positively correlated. The year of production influenced mainly (18)O/(16)O in relation to the amount of rainfall and the atmospheric humidity in the period of oil accumulation in the olives. The (2)H/(1)H ratio significantly distinguished the olive oils produced on the Adriatic coast from those on the Tyrrhenian coast in each year. This coast effect is a consequence of the different sources and isotopic compositions of the rainfall and the different climatic conditions on the two coasts. The paper contributes towards understanding the influence of climatic factors on isotopic variability and towards improving the traceability of the geographical origin of olive oils, using (2)H/(1)H as a more innovative parameter.

Multi-element (H,C,N,S) stable isotope characteristics of lamb meat from different European regions

Multi-element (H,C,N,S) stable isotope ratio analysis was tested for its suitability as a means for geographical provenance assignment of lamb meat from several European regions. The defatted dry matter (crude protein fraction) from lamb meat was found to be a suitable probe for "light" element stable isotope ratio analysis. Significant differences were observed between the multi-element isotope ratios of lamb samples from different regions. The mean hydrogen isotopic ratios of the defatted dry matter from lamb were found to be significantly correlated with the mean hydrogen isotopic ratios of precipitation and groundwater in the production regions. Carbon and nitrogen isotopic ratios were influenced by feeding practices and climate. Sulfur isotopic ratios were influenced by geographical location and surface geology of the production region. The results permitted differentiation of lamb meat, from most production regions, by inspection. However, more sophisticated evaluation of the data using multivariate methods, such as linear discriminant analysis, achieved 78% correct classification.

Correlation Between Multielement Stable Isotope Ratio and Geographical Origin in Peretta Cows’ Milk Cheese

The aim of this study was to characterize the isotopic composition and protect "Peretta" cows' milk cheese, a typical product of Sardinia, against other cheeses of the same appearance sold under the same name, but made of raw materials from northern Europe. The study was concerned with 3 types of cheese: those produced in local dairies from milk from free-grazing or pasture-grazing cows in Sardinia (local dairy product), cheeses made on an industrial scale from milk produced by intensive farming in Sardinia (factory cheese), and cheeses made with raw materials imported from other countries (imported product). To distinguish the Sardinian cheeses from the imported product, the stable isotope ratios 13C/12C, 15N/14N, D/H, 34S/32S, and (18)O/(16)O were used. Determination of the isotopic data delta13C, delta15N, delta2H, and delta34S was performed in the casein fraction, whereas delta(18)O and delta13C were determined in the glycerol fraction. Measurements were performed by isotope ratio mass spectrometry. A comparison between mean values of the isotope ratios by statistical analysis (ANOVA and Tukey's test) showed that the greatest difference between the 3 types of cheese (local dairy, factory, and imported products) was in the 13C/12C, 34S/32S, and (18)O/(16)O isotope ratios. In the other parameters, either no differences (delta15N) or minimal differences (delta2H) were found. Evaluation of the data by multivariate statistical analysis (principal component analysis and hierarchical cluster analysis) revealed that the isotope characteristics of the factory products were similar to those of the cheeses produced from imported raw materials, whereas a difference was found between the local dairy-produced cheeses and the products in the other 2 categories.

Detection of royal jelly adulteration using carbon and nitrogen stable isotope ratio analysis

Stable isotope ratios ((13)C/(12)C and (15)N/(14)N) were measured in royal jelly (RJ) samples by isotope ratio mass spectrometry (IRMS) to evaluate authenticity and adulteration. Carbon and nitrogen isotope contents (given as delta values relative to a standard, delta(13)C, delta(15)N) of RJ samples from various European origins and samples from commercial sources were analyzed. Uniform delta(13)C values from -26.7 to -24.9 per thousand were observed for authentic RJ from European origins. Values of delta(15)N ranged from -1.1 to 5.8 per thousand depending on the plant sources of nectars and pollen. High delta(13)C values of several commercial RJ samples from -20.8 to -13.3 per thousand indicated adulteration with high fructose corn syrup (HFCS) as a sugar source. Use of biotechnologically produced yeast powder as protein source for the adulterated samples was assumed as delta(15)N values were lower, as described for C(4) or CAM plant sources. RJ samples from authentic and from adulterated production were distinguished. The rapid and reliable method is suitable for urgent actual requirements in food monitoring.

Sucrose metabolism and exopolysaccharide production in wheat and rye sourdoughs by Lactobacillus sanfranciscensis

The exopolysaccharide (EPS) produced from sucrose by Lactobacillus sanfranciscensis LTH2590 is predominantly composed of fructose. EPS production during sourdough fermentation has the potential to affect rheological properties of the dough as well as the volume, texture, and keepability of bread. Its in situ production by L. sanfranciscensis LTH2590 was demonstrated during sourdough fermentation after the hydrolysis of water soluble polysaccharides. In wheat and rye doughs with sucrose addition the concentration of fructose in the hydrolysate of polysaccharides was significantly higher than that in the hydrolysate of control doughs or doughs without sucrose addition. EPS production by L. sanfranciscensis in wheat doughs was confirmed by the determination of delta (13)C values of water soluble polysaccharides after the addition of naturally labeled sucrose, originating from C(3)- and C(4)-plants. In rye doughs, evidence for EPS production with the isotope technique could be demonstrated only by the determination of delta (13)C values of fructose from water soluble polysaccharides. In addition to EPS formation from sucrose, sucrose hydrolysis by L. sanfranciscensis in wheat and rye sourdoughs resulted in an increase of mannitol and acetate concentrations and in accumulation of glucose. It was furthermore observed that flour arabinoxylans were solublized during the fermentation.

18O pattern and biosynthesis of natural plant products

Oxygen atoms in plant products originate from CO(2), H(2)O and O(2), precursors with quite different delta18O values. Furthermore their incorporation by different reactions implies isotope effects. On this base the resulting non-statistical 18O distributions in natural compounds are discussed. The delta18O value of cellulose is correlated to that of the leaf water, and the observed 18O enrichment (approximately +27 per thousand) is generally attributed to an equilibrium isotope effect between carbonyl groups and water. However, as soluble and heterotrophically synthesised carbohydrates show other correlations, a non-statistical 18O distribution - originating from individual biosynthetic reactions - is postulated for carbohydrates. Similarly, the delta18O values of organic acids, carbonyl compounds, alcohols and esters indicate water-correlated, but individual 18O abundances (e.g. O from acyl groups approximately +19% above water), depending upon origin and biosyntheses. Alcoholic groups introduced by monooxygenase reactions, e.g. in sterols and phenols, show delta18O values near +5 per thousand, in agreement with an assumed isotope fractionation factor of approximately 1.02 on the reaction with atmospheric oxygen (delta18O=+23.5 per thousand). Correspondingly, a "thermodynamically ordered isotope distribution" is only observed for oxygen in some functional groups correlated to an origin from CO(2) and H(2)O, not from O(2). The individual isotopic increments of functional groups permit the prediction of global delta18O values of natural compounds on the basis of their biosynthesis.

Sealing of postoperative axillary leakage after axillary lymphadenectomy using a fibrin glue coated collagen patch: a prospective randomised study

Seroma formation after axillary lymphadenectomy in women with breast cancer remains a problem despite many efforts to reduce surgery-related morbidity. In a prospective, randomised, open, parallel-group, controlled clinical trial we evaluated the effect of a fibrin-glue coated collagen patch (TachoComb H, Nycomed Pharma AS, Denmark) on volume and duration of postoperative axillary drainage, duration of hospital stay, and procedural safety. Sixty patients were included in the study. Patients did not differ with respect to general characteristics, such as age, body mass index, treatment modality, and tumor stage distribution. In 29 patients, a fibrin-glue coated collagen patch was applied from the apex axillae to the thoracic longus nerve and half a patch was applied to the lateral border of the axillary nerve-vessel bundle. Thirty-one patients were randomised to standard closure of the axillary lymphadenectomy area. The mean duration of axillary drainage was 3.8 +/- 1.9 days in the fibrin-glue treatment group and 3.9 +/- 1.8 days in the control group (p = NS). The mean total drainage volume was 338.5 +/- 251.8 ml in the fibrin-glue treatment group and 370.8 +/- 314.6 ml in the standard closure group (p = NS). The mean length of post-operative hospital stay was 9.1 +/- 2.7 days in the fibrin-glue treatment group and 9.3 +/- 3.6 days in the standard closure group (p = NS). Seven patients (25%) and eight patients (25%) were diagnosed with local inflammation in the fibrin-glue treatment group and the standard closure group, respectively (p = NS). Seroma formation after drain removal was found in 11 patients (39%) in the fibrin-glue treatment group and in 13 patients (42%) in the standard closure group (p = NS). In summary, we observed no statistically significant differences with respect to axillary drainage time, drainage volume, length of hospital stay, local inflammation, and seroma formation after drainage removal.

Determination of the (13)C Content of Glycerol Samples of Different Origin

The average carbon isotope value (delta(13)C) of 63 samples of glycerol from over 30 different sources has been determined. The results indicate that it is possible to distinguish the glycerol obtained from the glycerides produced in plants following C-3 and C-4 carbon fixation pathways. The samples obtained from animal sources seem to reflect the composition of the material consumed, as well as that produced by sugar fermentation.

Evidence for a nonstatistical carbon isotope distribution in natural glucose

The relative carbon isotope content (delta(13)C value) in each position of glucose from a C(4) plant (maize starch) and a C(3) plant (sugar beet sucrose) has been determined by stepwise chemical and biochemical degradation of the molecule and stable isotope ratio measurement of the fragments. The suitability of the degradation methods has been tested through their chemical yield and isotope balance. The results from both methods agreed perfectly, revealing a defined and reproducible (13)C distribution in glucose from both origins. Most prominent was a relative (13)C enrichment by 5 to 6 delta-units in position 4 and a depletion by about 5 delta-units in carbon 6. As possible reasons for these nonstatistical isotope distributions, isotope effects of the aldolase, the triose phosphate isomerase, and the transketolase reactions during carbohydrate biosynthesis are discussed. The practical importance of the results in regard to isotope distributions in secondary plant products as a means for food authenticity control is outlined.