It has been hypothesized that dysfunction of dopaminergic neurotransmission is involved in the pathogenesis of alcohol addiction. Therefore, peripheral dopamine levels, sensitivity of central dopamine receptors (apomorphine-induced Growth Hormone (GH) secretion), and the inhibitory efficacy of G-proteins on adenylyl cyclase activity (as an indicator for dopamine D2-receptor coupled second messenger mechanisms) were measured in 45 alcohol-dependent patients before and after detoxification and in 10 healthy controls. The time needed to adjust to abstinence conditions differed between patients with good and poor treatment outcome. In subsequent abstainers, effects of alcohol withdrawal were already found during the first 24 hours of abstinence (normalisation of GH response, increases in dopamine levels and the inhibitory efficacy of G-proteins). During the next 7 days of abstinence, no more significant changes were observed in the assessed variables. In subsequent relapsers, no significant effect of acute ethanol withdrawal on the same measures was found. However, at day 8 of abstinence, increases in apomorphine-induced GH secretion (towards normalisation), in dopamine plasma levels, and in the inhibitory efficacy of G-proteins (towards above-normal levels) were observed. This retarded adjustment of dopaminergic signal transduction seems to reflect the relapse risk of treatment nonresponders.

-Fourier-transform infrared spectroscopy (FT-IR) was used as a rapid, simple and reliable method for quality analysis of honey. More than 1600 samples of honey were analysed using FT-IR and reference methods to develop a partial least-square regression based calibration model for the major components of honey (sugars, proline, free acids, invertase, moisture, hydroxymethylfurfural, pH and electrical conductivity). The coefficient of determination R 2 ranging from 0.84-0.98 indicates an acceptable calibration for most of the parameters. Statistical verification of the spectral analysis in routine analysis showed a high correlation (0.81-0.99), good repeatability (0.84-0.99), no environmental influences (P > 0.05) and no significant statistical differences to the reference methods. This study shows that not only chemical composition but also the physical properties can be determined by FT-IR. The calibrations can be adapted to different analytical standards and honey sources. Fourier-transform infrared spectroscopy / FT-IR / honey quality/ sugar analysis

Marketing of adulterated beeswax foundation has recently become a major economic problem for beekeepers. Paraffin contamination leads to collapse of combs, and stearic acid has a negative influence on the development of bee brood. The quality of beeswax for beekeeping has not been standardized in EU regulations. Recently, it was shown that attenuated total reflectance Fourier-transform infrared spectroscopy (FTIR-ATR) can be used to determine beeswax adulteration. Differences in the IR spectra of authentic beeswax can be identified and calculated through comparison with authentic beeswax. In this study, the method is further validated by employing a high number of samples of authentic beeswax from different origins. Low quantification and detection limits are achieved for paraffin, stearic acid, tallow, carnauba wax, and candelilla wax. Furthermore, the FTIR-ATR analytical conditions are verified by analyzing 358 samples of commercial and beekeeper-produced beeswax foundations. Multi-adulterated samples with as many as five different additives in beeswax mixtures are identified with the same accuracy as single substances. Additionally, the spectra of a further 14 different natural and synthetic waxes and hardened fats are analyzed and are compared with beeswax. Finally, a spectral library is established that can be used for further studies. Practical Applications: FTIR-ATR is a fast and cost-efficient tool in beeswax analysis for accurately monitoring a high sample volume. Analysis of 358 beeswax foundations showed an adulteration of 21.8% of the samples with paraffin, stearic acid, tallow, and combinations. Based on the results of this study, it is possible to detect beeswax adulteration of less than 3% of these adulterants and their combinations by FTIR-ATR spectroscopy. This method can be used for monitoring beeswax foundations to identify adulterated materials, exclude these materials from the recycling process, and produce high-quality beeswax, which is essential for bee health.

No abstract

Analysis of the honey enzymes diastase and invertase is one important parameter in honey quality control. Limits for enzyme activity are given by food legislation or directives of national brands, because enzyme activity is one of the measures of adequate conversion of nectar to honey during the ripening process. In addition, certain activity levels of invertase or diastase activity can also act as indicators for heat damage of honey samples. Depending on the botanical origin, enormous differences in enzyme activity can be observed, even though the enzymes are mostly added by the bees. We therefore collected nectar and honey samples during the ripening process of honey and investigated enzyme activity depending on the floral source. Based on the analysis of nectar samples, we could demonstrate that floral source and environmental conditions affect the total sugars and sucrose concentration. We therefore hypothesized that the composition of the nectar, especially the amount of sucrose, may interact with the activity of invertase. We found that correlation between sucrose concentration and invertase activity is highly significant during the ripening process of honey (p < 0.0001) confirming an interaction between these two parameters. This effect was further substantiated by a sugar feeding experiment with defined sucrose concentrations. Possibly a high turn-over at high sucrose concentrations may lead to enzyme exhaustion for invertase.Evidencia de la correlación entre la actividad de la invertasa y el contenido de sacarosa durante el proceso de maduración de la miel Resumen El análisis de las enzimas diastasa e invertasa es un parámetro importante en el control de calidad de la miel. Los límites para la actividad enzimática son dados por la legislación alimentaria o directrices de las marcas nacionales, ya que la actividad de la enzima es una de las medidas de conversión adecuada de néctar a miel durante el proceso de maduración. Además, ciertos niveles de actividad de la invertasa o actividad de la diastasa también pueden actuar como indicadores de daño por calor de las muestras de miel. Dependiendo del origen botánico, se pueden observar enormes diferencias en la actividad de la enzima, a pesar de que las enzimas se añaden principalmente por las abejas.Por lo tanto, recogimos muestras de néctar y la miel durante el proceso de maduración de la miel e investigamos la actividad enzimática en función del origen floral. Basándonos en el análisis de muestras de néctar, pudimos demostrar que la fuente floral y las condiciones ambientales afectan la concentración de azúcares totales y de sacarosa. Por lo tanto, establecimos la hipótesis de que la composición del néctar, especialmente la cantidad de sacarosa, puede interactuar con la actividad de la invertasa. Se encontró que la correlación entre la concentración de sacarosa y la actividad de la invertasa es altamente significativa durante el proceso de maduración de la miel (p <0,0001) confirmando una interacción entre estos dos parámetros. Este efecto se fundamentó pos...