Cyclometalated N‐Heterocyclic Carbene‐Platinum Catalysts for the Enantioselective Cycloisomerization of Nitrogen‐Tethered 1,6‐Enynes

Platinum(II) complexes which combine six‐membered N‐heterocyclic carbene‐containing metallacyclic units and monodentate chiral phosphines have been prepared. The key step of their synthesis is the intramolecular oxidative addition of N‐2‐iodobenzylimidazolylidene‐platinum(0)‐diene complexes in the presence of the chiral phosphorus ligands. The platinum(II) metallacycles have been used as well‐defined pre‐catalysts for the enantioselective cycloisomerization of nitrogen‐tethered 1,6‐enynes into 3‐azabicyclo[4.1.0]hept‐4‐enes. High enantiomeric excesses have been obtained with either Monophos or phenyl‐Binepine based catalysts (ees=82–96%), although phenyl‐Binepine outperforms Monophos in these reactions. The absolute configuration of the final 3‐azabicyclo[4.1.0.]heptenes has been established by X‐ray diffraction studies. The method has been extended then to the cycloisomerization of dienynes with enantiotopic vinyl groups. An (S)‐phenyl‐Binepine‐platinum(II) complex allows total diastereoselectivity and high enantioselectivity levels to be attained in these reactions (ees up to 95%) which represent the first enantioselective desymetrizations achieved via enyne cycloisomerizations.     

Tyramine and phenylethylamine biosynthesis by food bacteria

Tyramine poisoning is caused by the ingestion of food containing high levels of tyramine, a biogenic amine. Any foods containing free tyrosine are subject to tyramine formation if poor sanitation and low quality foods are used or if the food is subject to temperature abuse or extended storage time. Tyramine is generated by decarboxylation of the tyrosine through tyrosine decarboxylase (TDC) enzymes derived from the bacteria present in the food. Bacterial TDC have been only unequivocally identified and characterized in Gram-positive bacteria, especially in lactic acid bacteria. Pyridoxal phosphate (PLP)-dependent TDC encoding genes (tyrDC) appeared flanked by a similar genetic organization in several species of lactic acid bacteria, suggesting a common origin by a single mobile genetic element. Bacterial TDC are also able to decarboxylate phenylalanine to produce phenylethylamine (PEA), another biogenic amine. The molecular knowledge of the genes involved in tyramine production has led to the development of molecular methods for the detection of bacteria able to produce tyramine and PEA. These rapid and simple methods could be used for the analysis of the ability to form tyramine by bacteria in order to evaluate the potential risk of tyramine biosynthesis in food products.     

'Fagiolo a Formella', an Italian lima bean ecotype: biochemical and nutritional characterisation of dry and processed seeds

BACKGROUND: An ecotype of the lima bean, named ‘fagiolo a Formella’, which, to the best of our knowledge, is the only example of an Italian lima bean (Phaseolus lunatus L.) ecotype, is cultivated in the Campania region of southern Italy. Physical, nutritional and processing traits of dry seeds were evaluated for two consecutive growing seasons (2009 and 2010). The canning quality was also investigated, but only for the harvest of 2010. RESULTS: Sodium dodecyl sulfate–polyacrylamide gel electrophoresis of total seed proteins allowed the attribution of ‘fagiolo a Formella’ to the Mesoamerican gene pool and Sieva morphotype. Seeds have a trapezoid shape, white coat and 100‐seed weight greater than 42 g. Yield, protein, trypsin inhibitor and phytic acid values were found comparable with those reported for lima bean varieties cultivated in sub‐tropical areas. Moreover, we found that this ecotype is devoid of lectin. CONCLUSIONS: The good adaptation to growing environment is indicated by the fact that ‘fagiolo a Formella’ seed quality is comparable to that of lima beans grown in America. Overall the canning quality was found satisfactory and canning significantly destroys the main anti‐nutritional compounds present in dry seeds. Copyright © 2012 Society of Chemical Industry     

Computational analysis of contractility in engineered heart tissue

Engineered heart tissue (EHT) is a potential therapy for heart failure and the basis of functional in vitro assays of novel cardiovascular treatments. Self-organizing EHT can be generated in fiber form, which makes the assessment of contractile function convenient with a force transducer. Contractile function is a key parameter of EHT performance. Analysis of EHT force data is often performed manually; however, this approach is time consuming, incomplete and subjective. Therefore, the purpose of this study was to develop a computer algorithm to efficiently and objectively analyze EHT force data. This algorithm incorporates data filtering, individual contraction detection and validation, inter/intracontractile analysis and intersample analysis. We found the algorithm to be accurate in contraction detection, validation and magnitude measurement as compared to human operators. The algorithm was efficient in processing hundreds of data acquisitions and was able to determine force-length curves, force-frequency relationships and compare various contractile parameters such as peak systolic force generation. We conclude that this computer algorithm is a key adjunct to the objective and efficient assessment of EHT contractile function.     

Use of infrared ocular thermography to assess physiological conditions of pigs prior to slaughter and predict pork quality variation

Infrared thermography (IRT) body temperature readings were taken in the ocular region of 258 pigs immediately before slaughter. Levels of lactate were measured in blood taken in the restrainer. Meat quality was assessed in the longissimus dorsi (LD), semimembranosus (SM), and adductor muscles. Ocular IRT (IROT) temperature was correlated with blood lactate levels (r = 0.20; P = 0.001), with pH taken 1 hour postmortem (pH1: r = − 0.18; P = 0.03) and drip loss (r = 0.20; P = 0.02) in the LD muscle, and with pH1 in the SM muscle (r = − 0.20; P = 0.02). Potentially, IROT may be a useful tool to assess the physiological conditions of pigs at slaughter and predict the variation of important meat quality traits. However, the magnitude of the correlations is rather low, so a further development of image capture technique and further studies under more variable preslaughter conditions ensuring a larger pork quality variation are needed.     

Biodiversity and characterization of indigenous coagulase-negative staphylococci isolated from raw milk and cheese of North Italy

The aim of the current study was to detect coagulase-negative staphylococci (CNS) in raw milk and cheeses produced in North Italy, and to analyze isolates for their biodiversity, safety aspects and technological properties. Molecular identification methods revealed a high biodiversity among isolates and assigned them to 17 species. The most recovered species were Staphylococcus equorum (12%), Staphylococcus lentus (12%), Staphylococcus simulans (12%), Staphylococcus sciuri (10%), and Staphylococcus xylosus (9%). The presence of ten transferable antibiotic resistance (AR) genes was verified by PCR and 19% of isolates were positive, with tet(K) being the most frequent gene (10%); interestingly, no strain carried multiple AR genes. Twenty-four isolates displayed hemolytic activity; tyrosine decarboxylase gene (tdcA) was found in two isolates, while histidine decarboxylase gene (hdcA) and enterotoxin genes (se) were not detected. Isolates were further characterized for the presence of some relevant technological properties; 16% of isolates displayed proteolytic activity and 39% lipolytic activity, while no one of the isolates was found to exhibit antimicrobial activity against Staphylococcus aureus. This study provided evidence of a low occurrence of safety hazards in CNS isolated from dairy products.     

Acid-insoluble ash as a marker compound for use in digestibility studies with humans

The study aimed to evaluate acid-insoluble ash, in the form of added celite (a diatomaceous earth), as an indigestible marker compound for use in digestibility studies with humans. The study comprised two parts. First, the recovery of dietary acid-insoluble ash in the faeces was determined in a controlled 10-day metabolism study involving five 6-week-old male pigs receiving food consisting of ingredients commonly eaten by humans. Secondly, the faecal recovery of dietary acid-insoluble ash was determined with six adult humans following a set diet which maintained their normal levels of daily food intake for 7 days. The mean (±SE) recoveries of dietary acid-insoluble ash in the faeces of the pigs and human subjects were 90·0 (±2·24) and 92·1 (±4·59)%, respectively. The mean apparent faecal digestibility coefficients for dietary dry matter were not significantly different (P > 0·05) when determined by total faeces collection or by reference to the marker, in both species. It was concluded that celite is a potentially useful dietary marker compound for use in human digestibility studies involving collection of faeces. The marker was readily accepted by the human subjects and can be determined chemically using simple gravimetric analysis.     

Exposure of an adult population to perfluorinated substances using duplicate diet portions and biomonitoring data

Because dietary intake is supposed to be an important route of human exposure we quantified the dietary intake of perfluorooctane sulfonate (PFOS), perfluorooctanoate (PFOA), perfluorohexane sulfonate (PFHxS), perfluorohexanoate (PFHxA), and perfluorooctane sulfonamide (PFOSA) using 214 duplicate diet samples. The study was carried out with a study population of 15 female and 16 male healthy subjects aged 16-45 years. The participants collected daily duplicate diet samples over seven consecutive days in 2005. Duplicate samples were homogenized and their ultrasonic extracts were cleaned up by SPE and subjected to HPLC-ESI-MS/MS. In addition, individual intakes were estimated based on blood levels of PFOS and PFOA using a pharmacokinetic model. Blood samples were collected once during the sampling period. The median (90th percentile) daily dietary intake of PFOS and PFOA was 1.4 ng/kg b.w. (3.8 ng/kg b.w.) and 2.9 ng/kg b.w. (8.4 ng/kg b.w.), respectively. PFHxS and PFHxA could be detected only in some samples above detection limit with median (maximum) daily intakes of 2.0 ng/kg b.w. (4.0 ng/kg b.w.) and 4.3 ng/kg b.w. (9.2 ng/kg b.w.), respectively. Because PFOSA could not be detected above the limit of detection of 0.2 ng/g f.w. this indirect route of exposure seems to be of less significance. Overall, the results of this study demonstrate that the German population is exposed to PFOS and PFOA, but the median dietary intake did not reach the recommended tolerable daily intake by far. Biomonitoring data predict an exposure in a comparable range. We suppose that, normally, food intake is the main source of exposure of the general population to PFOS and PFOA.