Thymol affects various types of tumor cell lines, including colorectal cancer cells. However, the hydrophobic properties of thymol prevent its wider use. Therefore, new derivatives (acetic acid ...thymol ester, thymol β-D-glucoside) have been synthesized with respect to hydrophilic properties. The cytotoxic effect of the new derivatives on the colorectal cancer cell lines HT-29 and HCT-116 was assessed via MTT assay. The genotoxic effect was determined by comet assay and micronucleus analysis. ROS production was evaluated using ROS-Glo™ H
O
Assay. We confirmed that one of the thymol derivatives (acetic acid thymol ester) has the potential to have a cyto/genotoxic effect on colorectal cancer cells, even at much lower (IC
~0.08 μg/mL) concentrations than standard thymol (IC
~60 μg/mL) after 24 h of treatment. On the other side, the genotoxic effect of the second studied derivative-thymol β-D-glucoside was observed at a concentration of about 1000 μg/mL. The antiproliferative effect of studied derivatives of thymol on the colorectal cancer cell lines was found to be both dose- and time-dependent at 100 h. Moreover, thymol derivative-treated cells did not show any significantly increased rate of micronuclei formation. New derivatives of thymol significantly increased ROS production too. The results confirmed that the effect of the derivative on tumor cells depends on its chemical structure, but further detailed research is needed. However, thymol and its derivatives have great potential in the prevention and treatment of colorectal cancer, which remains one of the most common cancers in the world.
While fixed effects (FE) models are often employed to address potential omitted variables, we argue that these models' real utility is in isolating a particular dimension of variance from panel data ...for analysis. In addition, we show through novel mathematical decomposition and simulation that only one-way FE models cleanly capture either the over-time or cross-sectional dimensions in panel data, while the two-way FE model unhelpfully combines within-unit and cross-sectional variation in a way that produces un-interpretable answers. In fact, as we show in this paper, if we begin with the interpretation that many researchers wrongly assign to the two-way FE model-that it represents a single estimate of X on Y while accounting for unit-level heterogeneity and time shocks-the two-way FE specification is statistically unidentified, a fact that statistical software packages like R and Stata obscure through internal matrix processing.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Chronic obstructive pulmonary disease (COPD) is a major cause of death worldwide. Acute exacerbations COPD (AECOPD), caused by infectious and non-infectious agents, contribute to an increase in ...mortality. The diagnostic procedure of AECOPD is mainly based on clinical features. The aim of this pilot study was to identify whether volatile organic compounds (VOCs) in breath could be used to discriminate for acute exacerbated COPD. Three patient groups were included in this controlled study: AECOPD patients (n = 14, age mean SD: 71.4 7.46), stable COPD patients (n = 16, age mean SD: 66.9 9.05) and healthy volunteers (n = 24, age mean SD: 28 6.08). Breath samples were collected by optimizing a sampling strategy developed by us. These samples were then analyzed using a thermal desorption-gas chromatography-time of flight-mass spectrometer (TD-GC-ToF-MS). A total of 105 VOCs were identified in the breath samples. Relevant substances were subsequently selected by overall occurrence rate, the frequency of positive alveolar gradient (AG) (i.e. the difference in exhaled and inhaled VOCs concentration), exclusion of 'smoking related' VOCs and significant differences in AGs between the three groups. These steps dramatically reduced the number of relevant analytes and resulted in 12 key VOCs having discriminative values. The performance of patients' classification described by the Receiver Operating Characteristic (ROC) curve using all 12 substances delineates an area under the curve (AUC) of 0.97. A further reduction to four VOCs (AGs only different between AECOPD and COPD) delineates an AUC of 0.92. These results indicate that breath analysis with TD-GC-ToF-MS holds promise for an accurate and easy to perform differential diagnosis between AECOPD and COPD. In this regard, ketones were observed at the highest levels in exhaled breath of AECOPD, some of which are also related to potential bacterial pathogens. Using a set of VOCs that can discriminate for AECOPD, the calculated AUCs in ROC curve analysis show far superior results in comparison to serum AECOPD biomarkers, such as C-reactive protein. The identified VOCs should be further investigated in translational studies addressing their potential for developing highly specific nanosensors for breath gas analysis which would give clinicians a tool for non-invasive diagnosis of AECOPD at the point of care.
The present work shows the possibility of using the GC-MS method for the qualitative and quantitative determination of major capsaicinoids in ground chillies, chilli sauces and in potato chips with ...chilli flavoring, which is competitive with already published LC methods. Treatment of samples before GC-MS analysis takes only 30 min. The new method does not require the use of large amounts of organic solvents for extraction or any purification step, as the treatment consists only direct derivatization of major capsaicinoids with hexamethyldisilazane. The new method was validated with a linear calibration range of 0.025–810 µg mL−1 for capsaicin-trimethylsilyl (TMS) and 0.04–440 µg mL−1 for dihydrocapsaicin-TMS. The derivatization efficiency, i.e. the conversion of capsaicin and dihydrocapsaicin to TMS derivatives is 100 % after 30 min of reaction. With the newly developed method, we achieved a good recovery of capsaicin and dihydrocapsaicin in selected ground chilli peppers, chili sauces and potato chips. In the 25 analyzed samples, the capsaicin content was in the range 0.00014–9.86 % and the dihydrocapsaicin content 0.00022–3.45 %, respectively. The suitability of the developed method was confirmed by the agreement of achieved data with that obtained using standard AOAC method in the range less than 5 %. Additionally, this method allows the analysis of samples with a high content of lipid components, sugars, salt or water, which do not interfere with the analysis.
•A new GC-MS method for the capsaicin determination in various types of food samples•Method for analysis of samples with a high content of fat, salt, sugar, and water•Treatment of samples by in situ silylation without extraction step in 30 min•Wide linear range and low LOD and LOQ values•At least two-fold increase in sensitivity compared to previous GC methods
The aim of the work was to analyze the influence of process parameters of high shear granulation on the process yield and on the morphology of granules on the basis of dynamic image analysis. The ...amount of added granulation liquid had a significant effect on all monitored granulometric parameters and caused significant changes in the yield of the process. In regard of the shape, the most spherical granules with the smoothest surface were formed at a liquid to solid ratio of ≈1. The smallest granules were formed at an impeller speed of 700 rpm, but the granules formed at 500 rpm showed both the most desirable shape and the highest process yield. Variation in the shape factors relied not only on the process parameters, but also on the area equivalent diameter of the individual granules in the batch. A linear relationship was found between the amount of granulation liquid and the compressibility of the granules. Using response surface methodology, models for predicting the size of granules and process yield related to the amount of added liquid and the impeller speed were generated, on the basis of which the size of granules and yield can be determined with great accuracy.
A newly designed needle trap device with Carbopack X as a sorbent material is used for sampling, preconcentration and injection of volatile analytes benzene, toluene, ethylbenzene and xylenes (BTEX) ...into gas chromatograph. The closed system of stripping the analytes from water samples was used. An injection port with a modified metal liner was used to desorb analytes trapped in needle trap device. The main advantage of needle trap device consists in the simple methodology and easiness and rapidity of the analysis. Needle trap device is suitable for sampling in field. The experimental parameters as breakthrough volume of stripping gas, linearity, repeatability and limit of detection (LOD) and quantification (LOQ) were investigated. LOD ranges from 0.05 to 0.07
μg
L
−1 and relative standard deviation ranges from 0.5% to 11.6% at concentrations 5 and 0.1
μg
L
−1, respectively.
The fatty acid (FA) composition in the intramuscular fat (IMF) of the musculus longissimus dorsi (MLD) of Ile de France purebred lambs in two different production systems in Slovakia was evaluated ...using gas chromatography. In the first production system, lambs and ewes were assigned to pasture without access to concentrates (P). In the second system, lambs and ewes were confined indoors with hay/silage and access to concentrates (S). An analysis of variance with the following factors was employed: production system, sex, and production system-sex interactions. The proportions of arachidonic, eicosapentaeonic, docosapentaeonic, and docosahexaenoic FAs, i.e. long-chain polyunsaturated FA (PUFA), were significantly higher in P lambs (1.83, 0.82, 0.92, 0.29 g 100 g
FAME, respectively) than in S lambs (0.45, 0.14, 0.30, 0.09 g 100 g
FAME, respectively). The proportions of conjugated linoleic acid (CLA), n-6 PUFA, n-3 PUFA, and essential FA (linoleic and
-linolenic) were also significantly higher in P lambs (2.10, 8.50, 4.55, and 8.80 g 100 g
FAME, respectively) than in S lambs (0.65, 3.27, 1.50, and 3.64 g 100 g
FAME, respectively). The proportions of palmitic acid and myristic acid as important individual saturated FAs (SFA) were significantly higher in S lambs (28.51 and 8.30 g 100 g
FAME, respectively) than in P lambs (21.80 and 5.63 g 100 g
FAME, respectively). The proportion of all SFAs was also significantly higher in S lambs (57.87 g 100 g
FAME) than in P lambs (48.70 g 100 g
FAME). From a nutrition and human health point of view (i.e. higher proportions of PUFA, CLA, and essential FAs and lower proportions of SFAs), meat from P lambs was found to be more favourable and would be more highly recommended for consumption.
Thymol is a substance with a great therapeutic potential possessing antibacterial and antifungal activity, with a characteristic odour that remains long after application but is not pleasant at ...higher concentrations. In this study, attention has been focused on describing the chemical and biological properties of the simply prepared trimethylsilyl ether of thymol (kubicin). Interestingly, kubicin has similar volatility as thymol, undergoes hydrolysis in the water (moisture; forming thymol and trimethylsilanol) and can be used at 6,000 times higher concentration than thymol without any negative and irritating odour. Kubicin showed diverse fungistatic and fungicidal activities when tested by direct contact assay, or in vapour phase. The volatile vapour of kubicin was effective on all tested fungal strains. These results suggest that vapours of kubicin might provide an alternative way to fight against fungal contamination.
Presented method for determination of sum of phthalates is based on their alkaline hydrolysis to phthalic acid at 80
°C for 20
h, followed by the selective extraction of lipophilic interferents from ...acidified hydrolysate at pH 1 with
n-hexane. Phthalic acid is derivatized to dimethyl phthalate (DMP) with diazomethane in aqueous-chloroform two-phase system. Resulting DMP is absorbed in chloroform and determined by GC-FID. Method calibration resulted in LOD and LOQ of 0.4 (2.1) and 1.2 (6.2) μg
g
−1 (nmol
g
−1) DMP, respectively. Real samples of Baltic herring and codfish, butter, pork, goose and duck fats, sunflower, olive, rapeseed and linseed oils were analysed and the background corrected total phthalates content was found in the range from not detected level in duck fat to 12.5 (64.3) μg
g
−1 (nmol
g
−1) in butter, respectively.
I propose a new model, ordered Beta regression, for continuous distributions with both lower and upper bounds, such as data arising from survey slider scales, visual analog scales, and dose–response ...relationships. This model employs the cut point technique popularized by ordered logit to fit a single linear model to both continuous (0,1) and degenerate 0,1 responses. The model can be estimated with or without observations at the bounds, and as such is a general solution for these types of data. Employing a Monte Carlo simulation, I show that the model is noticeably more efficient than ordinary least squares regression, zero-and-one-inflated Beta regression, rescaled Beta regression, and fractional logit while fully capturing nuances in the outcome. I apply the model to a replication of the Aidt and Jensen (2014, European Economic Review 72, 52–75) study of suffrage extensions in Europe. The model can be fit with the R package ordbetareg to facilitate hierarchical, dynamic, and multivariate modeling.
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