Ability of surface-active antioxidants to inhibit lipid oxidation in oil-in-water emulsion

Lipid oxidation in dispersed lipids is prevalent at the oil-water interface where lipid hydroperoxides are decomposed into free radicals by transition metals. Free radical scavenging antioxidants are believed to be most effective in lipid dispersions when they accumulate at the oil-water interface. The surface activity of antioxidants could be increased by their conjugation to hydrocarbon chains. In this study, p-hydroxyphenylacetic acid (HPA) was conjugated with either a butyl or dodecyl group. The HPA conjugates were more effective at decreasing interfacial tension than unconjugated HPA, indicating that they were able to adsorb at lipid-water interfaces. However, free HPA was a more effective antioxidant than butyl and dodecyl conjugates in Menhaden oil-in-water emulsions as determined by both lipid hydroperoxides and thiobarbituric acid reactive substances. The increased antioxidant activity of free HPA could be due to its more effective free radical scavenging activity and its higher concentration in the lipid phase of oil-in-water emulsions in the presence of surfactant micelles where it can act as a chain-breaking antioxidant.     

Comment on "Impaired respiratory and body temperature control upon acute serotonergic neuron inhibition"

Ray et al. (Reports, 29 July 2011, p. 637) assume that clozapine-N4-oxide (CNO) represents a "biologically inert synthetic ligand" that selectively activates the M4 muscarinic receptor-based DREADD (designer receptor exclusively activated by a designer drug). In contrast, due to the redox cycling of CNO with clozapine and to their cell membrane permeability, CNO is biologically active and its conversion products are capable of undermining DREADD effects.     

Estimating N rhizodeposition of grain legumes using a N in situ stem labelling method

Grain legumes in crop rotations cause significant increases in yield for succeeding non-legumes, which cannot be explained simply by the small effect that legumes have on the soil nitrogen balance, as found in the analysis of N in crop residues. Besides known positive non-N-effects, other effects, mainly rhizodeposition and its contribution to the N balance and nitrogen dynamics after harvesting the grain, are poorly understood. In this study, N rhizodeposition, defined as root-derived N in the soil after removal of visible roots, was measured in faba bean (Vicia faba L.), pea (Pisum sativum L.) and white lupin (Lupinus albus L.). In a pot experiment the legumes were pulse labelled in situ with ¹⁵N urea using a cotton wick method. About 84% of the applied ¹⁵N was recovered for the three legume species at maturity. The ¹⁵N was comparatively uniformly distributed among plant parts. The N rhizodeposition constituted 13% of total plant N for faba bean and pea and 16% for white lupin at maturity, about 80% of below ground plant N, respectively. Some 7% (lupin)-31% (pea) of the total N rhizodeposits were recovered as micro-roots by wet sieving (200 μm) the soil after all visible roots had been removed. Only 14-18% of the rhizodeposition N was found in the microbial biomass and a very small amount of 3-7% was found in the mineral N fraction. In pea, 48% and in lupin 72% of N rhizodeposits could not be recovered in the mentioned pools and a major part of the unrecovered N was probably immobilised in microbial residues. The results of this study clearly indicate that N rhizodeposition from grain legumes represent a significant pool for N balance and N dynamics in crop rotations.     

Homocysteine and cobalamin status in German vegans

OBJECTIVE: The study aimed to evaluate the homocysteine and cobalamin status of German vegans and determine whether the intake of very small amounts of foods of animal origin can improve this status. DESIGN AND SETTING: Cross-sectional study, Germany. SUBJECTS: The dietary and nutritional intakes of 131 vegans (73 women, 58 men; age range: 20.2-82.1 years) were evaluated using a general questionnaire and two food-frequency questionnaires. RESULTS: The prevalence of inadequate cobalamin status in volunteers of the German Vegan Study was 28.2%, and that of hyperhomocysteinaemia, 38.1%. Moderate vegans were affected to a lesser extent than were strict vegans. Duration of veganism and cobalamin concentration were inversely correlated (Spearman's r=-0.175, P=0.047). Folate concentration and erythrocyte aspartic acid aminotransferase activity were not correlated with plasma homocysteine concentration, but duration of veganism correlated positively with homocysteine concentration (Spearman's r=0.319, P<0.001). Cobalamin and homocysteine concentrations were inversely correlated (when controlling for duration of veganism; r=-0.602, P<0.001). CONCLUSION: Cobalamin status needs to be improved in order to minimise the risk of hyperhomocysteinaemia.     

Crystal structure of the potassium channel KirBac1.1 in the closed state

The KirBac1.1 channel belongs to the inward-rectifier family of potassium channels. Here we report the structure of the entire prokaryotic Kir channel assembly, in the closed state, refined to a resolution of 3.65 angstroms. We identify the main activation gate and structural elements involved in gating. On the basis of structural evidence presented here, we suggest that gating involves coupling between the intracellular and membrane domains. This further suggests that initiation of gating by membrane or intracellular signals represents different entry points to a common mechanistic pathway.     

Investigations into the use of respiratory masks for reducing the MRSA-exposure of veterinarians visiting regularly pig herds--first experiences

The study presents first experiences on the controlled use of respiratory masks against Methicillin-resistant Staphylococcus aureus (MRSA) in a multi-person veterinary pig practice. Seven veterinarians entered the trial (five wearing masks, two wearing no masks) after the veterinarians had performed a decolonisation protocol. The pig herds were visited regularly by the veterinarians during the study period. The five "trial" veterinarians wore gloves and respiratory masks for at least 30 days and 30 farm visits. The two "control" veterinarians wore gloves only. Nasal swabs were collected at a seven day interval. Swabs and ten masks per "trial" veterinarian were bacteriologically tested for MRSA including MLST- and spa-typing. The study showed a high MRSA-exposure for the veterinarians, since 68% of the masks were tested positive for MRSA. However, four vets stayed MRSA-negative while using the masks. Only one of the"trial" veterinarians became positive after two weeks. After the masks were not worn any more, two veterinarians returned to colonisation soon again. The two "control" veterinarians turned positive after 26 and 54 days, respectively. The high finding-rates of MRSA in the masks proof an enormous risk of nasal colonisation during routine work.The results of our study do not proof the potential of respiratory masks to prevent nasal colonisation of veterinarians with MRSA. However, there are no hints, that the proper use of masks could be a risk factor for becoming colonised. Further details of the proper use of masks and the quantification of their protective potential need further studies on a larger scale.     

EPOXI at comet Hartley 2

Understanding how comets work--what drives their activity--is crucial to the use of comets in studying the early solar system. EPOXI (Extrasolar Planet Observation and Deep Impact Extended Investigation) flew past comet 103P/Hartley 2, one with an unusually small but very active nucleus, taking both images and spectra. Unlike large, relatively inactive nuclei, this nucleus is outgassing primarily because of CO(2), which drags chunks of ice out of the nucleus. It also shows substantial differences in the relative abundance of volatiles from various parts of the nucleus.     

Occurrence of MRSA in air and housing environment of pig barns

A high prevalence of MRSA among farm animals, especially pigs, has been observed for some time. However, knowledge on transmission routes of MRSA in livestock production is still scarce. Therefore, the aim of this study was to determine the occurrence of MRSA in pig house air as well as in samples from pigs and their housing environment in 27 MRSA positive pig barns of different sizes and production types. In 85.2% of all barns MRSA was detected in the animal house air. Impingement turned out to be a more sensitive sampling technique than filtration. Other environmental samples such as boot swabs or faeces showed prevalences of MRSA from 55.6% to 85.2% at sample level. The level of MRSA was 88.3% for pooled and 82.1% for single nasal swabs, in skin swabs the one was 87.7%, the others was 78.7%. Spa typing of isolates from air and nasal swabs showed predominantly spa types t011 and t034. MRSA prevalences in pigs as well as in various environmental samples were significantly higher in fattening farms than in breeding farms. This study provides good reference that there could be an airborne transmission of MRSA within pig herds indicating a potential contamination of the environment of barns.