The nucleus of 103P/Hartley 2, target of the EPOXI mission

103P/Hartley 2 was selected as the target comet for the Deep Impact extended mission, EPOXI, in October 2007. There have been no direct optical observations of the nucleus of this comet, as it has always been highly active when previously observed. We aimed to recover the comet near to aphelion, to a) confirm that it had not broken up and was in the predicted position, b) to provide astrometry and brightness information for mission planning, and c) to continue the characterisation of the nucleus. We observed the comet at heliocentric distances between 5.7 and 5.5 AU, using FORS2 at the VLT, at 4 epochs between May and July 2008. We performed VRI photometry on deep stacked images to look for activity and measure the absolute magnitude and therefore estimate the size of the nucleus. We recovered the comet near the expected position, with a magnitude of m_R = 23.74 \pm 0.06 at the first epoch. The comet had no visible coma, although comparison of the profile with a stellar one showed that there was faint activity, or possibly a contribution to the flux from the dust trail from previous activity. This activity appears to fade at further epochs, implying that this is a continuation of activity past aphelion from the previous apparition rather than an early start to activity before the next perihelion. Our data imply a nucleus radius of \le 1 km for an assumed 4% albedo; we estimate a ~6% albedo. We measure a colour of (V-R) = 0. 26 \pm 0.09.Comment: 5 pages, 4 figures, accepted for publication in A&

Microelectrochemical Sensors for In Vivo Brain Analysis: An Investigation of Procedures for Modifying Pt Electrodes Using Nafion®

Various Nafion® coating procedures were examined in order to design a simple and reproducible coating method to maximise permselective characteristics, and thus eliminate signals from electroactive interferents, in sensors designed for direct in vivo measurements in the brain. Interferents investigated included ascorbic acid (AA), the principal endogenous electroactive interferent present in the brain, and uric acid. Application of the Nafion® (5% commercial solution) using a thermally annealing procedure involving 5 pre-coats, and 2 subsequent dip-bake layers resulted in elimination of interferent signals. It also produced complete blocking of the signal for the neurotransmitter dopamine. The optimum time and temperature for annealing was found to be 5 min at 210 °C. An examination of shelf life over two weeks indicated negligible AA interference over this period. Preliminary investigations with respect to the potential use of these Nafion®-modified Pt electrodes in the design of implantable, first generation, peroxide detecting biosensors indicated that the modified electrode had no effect on O2 permeability but did produce a significant decrease in H2O2 sensitivity. While this may preclude their use in biosensor development they may be more suitable for detection of gaseous neurochemicals such as nitric oxide

Monoamine oxidase-A modulates apoptotic cell death induced by staurosporine in human neuroblastoma cells

Monoamine oxidases (MAOs) are mitochondrial enzymes which control the levels of neurotransmitters in the brain and dietary amines in peripheral tissues via oxidative deamination. MAO has also been implicated in cell signalling. In this study, we describe the MAO-A isoform as functional in apoptosis induced by staurosporine (STS) in human dopaminergic neuroblastoma cells (SH-SY5Y). Increased levels of MAO-A activity were induced by STS, accompanied by increased MAO-A protein and activation of the initiator of the intrinsic pathway, caspase 9, and the executioner caspase 3. MAO-A mRNA levels were unaffected by STS, suggesting that changes in MAO-A protein are due to post-transcriptional events. Two unrelated MAO-A inhibitors reduced caspase activation. STS treatment resulted in sustained activation of the mitogen-activated protein kinase pathway enzymes extracellular regulated kinase, c-jun terminal kinase and p38, and depletion of the anti-apoptotic protein Bcl-2. These changes were significantly reversed by MAO inhibition. Production of reactive oxygen species was increased following STS exposure, which was blocked by both MAO inhibition and the antioxidant N-acetylcysteine. Therefore our data provide evidence that MAO-A, through its production of reactive oxygen species as a by-product of its catalytic activity on the mitochondrial surface, is recruited by the cell to enhance apoptotic signalling

Heat lability of NADPH at physiologic p H

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44179/1/10528_2004_Article_BF00484822.pd

Yellow pea flour and protein isolate as sources of antioxidant peptides after simulated gastrointestinal digestion

Although peas are widely consumed legumes throughout the world, the bioactivity ofthe peptides released by the gastrointestinal digestion has not been sufficiently studiedso far. The objective of the present work was to evaluate the potential of floursand protein isolates obtained from two varieties of yellow peas as sources of antioxidantpeptides. Flours and protein isolates were prepared and submitted to a simulatedgastrointestinal digestion. Protein hydrolysis degree (TNBS method) andprotein solubility (in phosphate buffer saline, pH = 7.4) values were independent onthe starting material. Antioxidant activity measured by oxygen radical absorbancecapacity (ORAC) and hydroxyl radical averting capacity (HORAC) showed no differencesbetween varieties. A lower activity was registered for protein isolates withrespect to flours in the case of HORAC, which could be associated with a loss of moleculeswith molecular masses lower than 43 kDa in the protein isolates. A significantincrease in activities was evidenced by both methods after gastrointestinal digestion,except in the case of HORAC activity of flours. Digested from protein isolates presenteda greater ratio of molecules smaller than 1.4 kDa and a lower ratio of thoselarger than 6.5 kDa with respect to digested flours, according to electrophoresis andgel filtration chromatography studies. Results suggested that the presence of othercomponents or/and the initial state of proteins would affect proteolytic attack ofdigestive enzymes. Both, pea flours and protein isolates, present interesting potentialas antioxidants food ingredients.Fil: Cipollone, María Agustina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; ArgentinaFil: Tironi, Valeria Anahi. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; Argentin

Detecting Specific Saccharides via a Single Indicator

An improved synthesis of a rhodamine boronic acid indicator is reported. This compound is used in an optimized data collection protocol for wavelength- and time-dependent selectivity of sugars such as fructose and ribose derivatives. One indicator is thus used to selectively distinguish structurally related sugar analytes

Experiment K-6-21. Effect of microgravity on 1) metabolic enzymes of type 1 and type 2 muscle fibers and on 2) metabolic enzymes, neutransmitter amino acids, and neurotransmitter associated enzymes in motor and somatosensory cerebral cortex. Part 1: Metabolic enzymes of individual muscle fibers; part 2: metabolic enzymes of hippocampus and spinal cord

The individual fibers of any individual muscle vary greatly in enzyme composition, a fact which is obscured when enzyme levels of a whole muscle are measured. The purpose of this study was therefore to assess the changes due to weightless on the enzyme patterns composed by the individual fibers within the flight muscles. In spite of the limitation in numbers of muscles examined, it is apparent that: (1) that the size of individual fibers (i.e., their dry weight) was reduced about a third, (2) that this loss in dry mass was accompanied by changes in the eight enzymes studied, and (3) that these changes were different for the two muscles, and different for the two enzyme groups. In the soleus muscle the absolute amounts of the three enzymes of oxidative metabolism decreased about in proportion to the dry weight loss, so that their concentration in the atrophic fibers was almost unchanged. In contrast, there was little loss among the four enzymes of glycogenolysis - glycolysis so that their concentrations were substantially increased in the atrophic fibers. In the TA muscle, these seven enzymes were affected in just the opposite direction. There appeared to be no absolute loss among the oxidative enzymes, whereas the glycogenolytic enzymes were reduced by nearly half, so that the concentrations of the first metabolic group were increased within the atrophic fibers and the concentrations of the second group were only marginally decreased. The behavior of hexokinase was exceptional in that it did not decrease in absolute terms in either type of muscle and probably increased as much as 50 percent in soleus. Thus, their was a large increase in concentration of this enzyme in the atrophied fibers of both muscles. Another clear-cut finding was the large increase in the range of activities of the glycolytic enzymes among individual fibers of TA muscles. This was due to the emergence of TA fibers with activities for enzymes of this group extending down to levels as low as those found in control soleus muscles. It would be interesting to know if this represents a transition stage, and whether with prolonged weightlessness most of the fibers would be transformed into a low glycogenolytic type

Bowhead Whale (Balaena mysticetus) Feeding near Point Barrow, Alaska, During the 1985 Spring Migration

Examination of stomach contents and behavioral observations showed conclusively that bowhead whales were feeding in the Point Barrow area during the spring of 1985. All three bowheads harvested near the village of Barrow had over five litres of pelagic zooplankton (calanoid copepods and euphausiids) in their stomachs. Over 60 whales were observed during the period 26 May through 6 June diving repeatedly under the landfast ice and feeding in an area 11.2 km southwest of Point Barrow. Observers recorded times for dive, surfacing and respiration intervals for these whales. The recorded times were significantly different from those of bowhead whales migrating past Point Barrow in the spring and from bowheads, whose major activity was feeding, recorded in the Canadian Beaufort Sea during the summer and fall.Key words: Balaena mysticetus, Point Barrow, feeding, bowhead whale, behavior, copepod,  euphausiid, respiration, springUn examen du contenu stomacal de baleines franches et des observations de leur comportement ont montré sans aucun doute qu’elles se nourrissaient dans la zone de Point Barrow pendant le printemps de1985. Les trois baleines franches pêchées près du village de Barrow avaient toutes dans l’estomac plus de cinq litres de zooplancton pélagique (copépodes calanoïdes et euphausiacés). Pendant la période allant du 26 mai au 6 juin, on a observé plus de 60 baleines qui plongeaient de façon répétée sous la banquise côtière pour se nourrir dans une zone située à 11,2 km au sud-ouest de Point Barrow. Les observateurs ont noté le moment de la plongée et celui du retour à la surface, et l’intervalle entre les souffles des baleines. Les durées enregistrées étaient nettement différentes de celles mesurées pour des baleines franches qui passaient à Point Barrow pendant leur migration au printemps, et de celles enregistrées dans la mer de Beaufort canadienne en été et en automne pour des baleines franches dont l’activité principale était de se nourrir.Mots clés: Balaena mysticetus, Point Barrow, se nourrir, baleine franche, comportement, copépode, euphausiacé, respiration, printemp

The Amundsen Sea Polynya International Research Expedition (ASPIRE)

In search of an explanation for some of the greenest waters ever seen in coastal Antarctica and their possible link to some of the fastest melting glaciers and declining summer sea ice, the Amundsen Sea Polynya International Research Expedition (ASPIRE) challenged the capabilities of the US Antarctic Program and RVIB Nathaniel B. Palmer during Austral summer 2010–2011. We were well rewarded by both an extraordinary research platform and a truly remarkable oceanic setting. Here we provide further insights into the key questions that motivated our sampling approach during ASPIRE and present some preliminary findings, while highlighting the value of the Palmer for accomplishing complex, multifaceted oceanographic research in such a challenging environment