Abundant molecular oxygen in the coma of comet 67P/Churyumov-Gerasimenko.

The composition of the neutral gas comas of most comets is dominated by H2O, CO and CO2, typically comprising as much as 95 per cent of the total gas density. In addition, cometary comas have been found to contain a rich array of other molecules, including sulfuric compounds and complex hydrocarbons. Molecular oxygen (O2), however, despite its detection on other icy bodies such as the moons of Jupiter and Saturn, has remained undetected in cometary comas. Here we report in situ measurement of O2 in the coma of comet 67P/Churyumov-Gerasimenko, with local abundances ranging from one per cent to ten per cent relative to H2O and with a mean value of 3.80 ± 0.85 per cent. Our observations indicate that the O2/H2O ratio is isotropic in the coma and does not change systematically with heliocentric distance. This suggests that primordial O2 was incorporated into the nucleus during the comet's formation, which is unexpected given the low upper limits from remote sensing observations. Current Solar System formation models do not predict conditions that would allow this to occur.

Molecular nitrogen in comet 67P/Churyumov-Gerasimenko indicates a low formation temperature.

Molecular nitrogen (N2) is thought to have been the most abundant form of nitrogen in the protosolar nebula. It is the main N-bearing molecule in the atmospheres of Pluto and Triton and probably the main nitrogen reservoir from which the giant planets formed. Yet in comets, often considered the most primitive bodies in the solar system, N2 has not been detected. Here we report the direct in situ measurement of N2 in the Jupiter family comet 67P/Churyumov-Gerasimenko, made by the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis mass spectrometer aboard the Rosetta spacecraft. A N2/CO ratio of (5.70 ± 0.66) × 10(-3) (2σ standard deviation of the sampled mean) corresponds to depletion by a factor of ~25.4 ± 8.9 as compared to the protosolar value. This depletion suggests that cometary grains formed at low-temperature conditions below ~30 kelvin.

Cometary science. Time variability and heterogeneity in the coma of 67P/Churyumov-Gerasimenko.

Comets contain the best-preserved material from the beginning of our planetary system. Their nuclei and comae composition reveal clues about physical and chemical conditions during the early solar system when comets formed. ROSINA (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis) onboard the Rosetta spacecraft has measured the coma composition of comet 67P/Churyumov-Gerasimenko with well-sampled time resolution per rotation. Measurements were made over many comet rotation periods and a wide range of latitudes. These measurements show large fluctuations in composition in a heterogeneous coma that has diurnal and possibly seasonal variations in the major outgassing species: water, carbon monoxide, and carbon dioxide. These results indicate a complex coma-nucleus relationship where seasonal variations may be driven by temperature differences just below the comet surface.

Cometary science. 67P/Churyumov-Gerasimenko, a Jupiter family comet with a high D/H ratio.

The provenance of water and organic compounds on Earth and other terrestrial planets has been discussed for a long time without reaching a consensus. One of the best means to distinguish between different scenarios is by determining the deuterium-to-hydrogen (D/H) ratios in the reservoirs for comets and Earth's oceans. Here, we report the direct in situ measurement of the D/H ratio in the Jupiter family comet 67P/Churyumov-Gerasimenko by the ROSINA mass spectrometer aboard the European Space Agency's Rosetta spacecraft, which is found to be (5.3 ± 0.7) × 10(-4)­that is, approximately three times the terrestrial value. Previous cometary measurements and our new finding suggest a wide range of D/H ratios in the water within Jupiter family objects and preclude the idea that this reservoir is solely composed of Earth ocean-like water.

Direct observations of interstellar H, He, and O by the Interstellar Boundary Explorer.

Neutral gas of the local interstellar medium flows through the inner solar system while being deflected by solar gravity and depleted by ionization. The dominating feature in the energetic neutral atom Interstellar Boundary Explorer (IBEX) all-sky maps at low energies is the hydrogen, helium, and oxygen interstellar gas flow. The He and O flow peaked around 8 February 2009 in accordance with gravitational deflection, whereas H dominated after 26 March 2009, consistent with approximate balance of gravitational attraction by solar radiation pressure. The flow distributions arrive from a few degrees above the ecliptic plane and show the same temperature for He and O. An asymmetric O distribution in ecliptic latitude points to a secondary component from the outer heliosheath.

Global observations of the interstellar interaction from the Interstellar Boundary Explorer (IBEX).

The Sun moves through the local interstellar medium, continuously emitting ionized, supersonic solar wind plasma and carving out a cavity in interstellar space called the heliosphere. The recently launched Interstellar Boundary Explorer (IBEX) spacecraft has completed its first all-sky maps of the interstellar interaction at the edge of the heliosphere by imaging energetic neutral atoms (ENAs) emanating from this region. We found a bright ribbon of ENA emission, unpredicted by prior models or theories, that may be ordered by the local interstellar magnetic field interacting with the heliosphere. This ribbon is superposed on globally distributed flux variations ordered by both the solar wind structure and the direction of motion through the interstellar medium. Our results indicate that the external galactic environment strongly imprints the heliosphere.

The loss of ions from Venus through the plasma wake.

Venus, unlike Earth, is an extremely dry planet although both began with similar masses, distances from the Sun, and presumably water inventories. The high deuterium-to-hydrogen ratio in the venusian atmosphere relative to Earth's also indicates that the atmosphere has undergone significantly different evolution over the age of the Solar System. Present-day thermal escape is low for all atmospheric species. However, hydrogen can escape by means of collisions with hot atoms from ionospheric photochemistry, and although the bulk of O and O2 are gravitationally bound, heavy ions have been observed to escape through interaction with the solar wind. Nevertheless, their relative rates of escape, spatial distribution, and composition could not be determined from these previous measurements. Here we report Venus Express measurements showing that the dominant escaping ions are O+, He+ and H+. The escaping ions leave Venus through the plasma sheet (a central portion of the plasma wake) and in a boundary layer of the induced magnetosphere. The escape rate ratios are Q(H+)/Q(O+) = 1.9; Q(He+)/Q(O+) = 0.07. The first of these implies that the escape of H+ and O+, together with the estimated escape of neutral hydrogen and oxygen, currently takes place near the stoichometric ratio corresponding to water.

Solar wind-induced atmospheric erosion at Mars: first results from ASPERA-3 on Mars Express.

The Analyzer of Space Plasma and Energetic Atoms (ASPERA) on board the Mars Express spacecraft found that solar wind plasma and accelerated ionospheric ions may be observed all the way down to the Mars Express pericenter of 270 kilometers above the dayside planetary surface. This is very deep in the ionosphere, implying direct exposure of the martian topside atmosphere to solar wind plasma forcing. The low-altitude penetration of solar wind plasma and the energization of ionospheric plasma may be due to solar wind irregularities or perturbations, to magnetic anomalies at Mars, or both.

Co-expression of beta-adrenergic receptors and cyclooxygenase-2 in pulmonary adenocarcinoma.

Pulmonary adenocarcinoma (PAC) is the leading type of lung cancer and is highly resistant to conventional cancer therapy. A better understanding of the regulatory mechanisms which control the growth of this deadly malignancy are urgently needed to develop more effective cancer intervention strategies. Recent studies have shown that PAC frequently overexpresses cyclooxygenase-2 (COX-2). This enzyme converts arachidonic acid (AA) into several metabolites, some of which have been identified as modulators of mitogenesis and apoptosis. Accordingly, the AA cascade and COX-2 are currently widely studied as potential targets for lung cancer prevention. Recent studies by our research group have shown that cell lines derived from human PACs express beta1- and beta2-adrenergic receptors, which regulate the release of AA and DNA synthesis. Moreover, we have demonstrated that an antagonist for beta-adrenergic receptors or aspirin inhibited the development of experimentally induced PAC in a hamster model. These findings suggest that beta-adrenergic receptors may serve as upstream regulators of AA and COX-2-mediated PAC growth. However, no information is currently available on the expression of beta-adrenergic receptors and its possible correlation with the expression of COX-2 in tissue samples from human PAC, casting some doubt on the significance of these findings in vitro and in an animal model. In the current study, we have therefore analyzed tissue samples of human PACs for the expression of beta1-and beta2-adrenergic receptors as well as COX-2 by reverse transcription polymerase chain reaction (RT-PCR) or immunohistochemistry. Our data show that seven out of eight samples co-expressed COX-2 and one or both of these beta-adrenergic receptors, supporting the experimental evidence for a functional link between these neurotransmitter receptors and the AA cascade in the regulation of human PAC.

Malignant teratoid medulloepithelioma in a llama.

A lesion was identified in the eye of a juvenile llama, and preliminary clinical findings included anterior uveitis and an exudative retinal detachment suggestive of infectious disease. However, histopathologic evaluation of the enucleated globe revealed an intraocular neoplasm composed of primitive neuroepithelium forming ribbons, cords, and rosettes, heteroplastic elements including spindle cells in a loose myxomatous matrix, and islands of well-differentiated hyaline cartilage. Immunohistochemically, neoplastic cells were positive for vimentin and neuron-specific enolase. Spindle cells were multifocally positive for desmin and muscle specific actin, indicating differentiation towards myofibers. These findings are consistent with a diagnosis of malignant teratoid medulloepithelioma, an extremely rare ocular neoplasm that affects children and young animals.

Comparison of 225actinium chelates: tissue distribution and radiotoxicity.

The biodistribution and tissue toxicity of intravenously administered 225-actinium (225Ac) complexed with acetate, ethylene diamine tetraacetic acid (EDTA), 1, 4, 7, 10, 13-pentaazacyclopentadecane-N, N', N", N"', N""-pentaacetic acid (PEPA), or the "a" isomer of cyclohexyl diethylenetriamine pentaacetic acid (CHX-DTPA), were examined. The percent of injected dose per organ and per gram of tissue for each chelate complex was determined. 225Ac-CHX-DTPA was evaluated further for radiotoxic effects. Mice receiving > or =185 kBq 225Ac-CHX-DTPA suffered 100% morbidity by 5 days and 100% mortality by 8 days postinjection, and all animals evaluated had significant organ damage. The in vivo instability of the 225Ac-CHX-DTPA complex likely allowed accumulation of free 225Ac in organs, which resulted in tissue pathology.

Induction of prostaglandin G/H synthase-2 in a canine model of spontaneous prostatic adenocarcinoma.

BACKGROUND: Prostate cancer is the most frequently occurring cancer in men in the United States, with an estimated 179 300 new cases in 1999. The induction of prostaglandin G/H synthase (PGHS), a key rate-limiting enzyme in prostaglandin biosynthesis, has been implicated in various cancers, most notably in colorectal cancers; however, the induction of PGHS expression in prostate cancer in vivo has not been reported for any species. The dog is the only nonhuman species that frequently develops spontaneous cancer of the prostate with increasing age, and the objective of this study was to determine whether PGHS isoenzymes were expressed in canine prostatic adenocarcinomas. METHODS: Four normal canine prostatic tissues and 24 canine prostatic adenocarcinomas were studied by means of immunohistochemistry and immunoblot analysis, using polyclonal antibodies specific for each of the two PGHS isoenzymes, PGHS-1 and PGHS-2. All P values were obtained by use of two-sided Fisher's exact tests. RESULTS: PGHS-1 immunostaining was localized to stromal fibroblasts and vascular endothelium in normal and cancerous prostates. PGHS-2 was not detected in normal prostates, but it was expressed by epithelial tumor cells in 18 (75%) of the 24 adenocarcinomas (P =.01). Immunoblot analysis confirmed the presence of PGHS-1 (69 000 molecular weight) in normal and cancerous tissues and the expression of PGHS-2 (72 000- to 74 000-molecular-weight doublet) only in prostatic adenocarcinomas. CONCLUSION: To our knowledge, these results demonstrate for the first time that PGHS-2 is induced in the majority of canine spontaneous prostatic adenocarcinomas and suggest that its expression may be involved in prostate cancer.

Signaling pathways for tissue factor expression in lipopolysaccharide-stimulated bovine alveolar macrophages.

OBJECTIVE: To investigate receptor-mediated intracellular events in bovine alveolar macrophages (AM) stimulated by bacterial lipopolysaccharide (LPS), using tissue factor (TF) expression as the measurable functional endpoint. SAMPLE POPULATION: Pulmonary AM harvested from 1- to 4-month-old male Holstein calves. PROCEDURE: Alveolar macrophages, acquired by use of volume-controlled bronchopulmonary lavage, were treated with CD14 monoclonal antibody (20 microg/ml), pertussis toxin (300 ng/ml), or 1 of 3 known protein kinase C (PKC) inhibitors (10 microM chelerythrin, 100 microM H-7, or 50 nM staurosporin), then were stimulated with LPS alone (0.01, 0.10, 1.0, 10.0 microg/ml) or LPS (0.25, 0.5, 1.0 ng/ml) in combination with concentrated bovine serum fraction 2 (500 ng/ml). Tissue factor expression was quantified by use of a colorimetric assay. Changes in intracellular Ca2+ concentration and pH were monitored, using Ca2+- and pH-sensitive fluorescent dyes, with changes in fluorescent intensity after incubation with LPS measured by spectrophotometry. RESULTS: Treatment of AM with a CD14 monoclonal antibody caused profound inhibition of TF expression (P < 0.0001) after stimulation by LPS combined with bovine serum fraction 2. Pertussis toxin had a significant (P < 0.0319) inhibitory effect on TF expression when cells were stimulated by LPS alone. Treatment with all 3 PKC inhibitors caused marked reduction in TF expression of cells stimulated with LPS alone or with phorbol myristate acetate. Stimulation of cells by LPS failed to mobilize intracellular Ca2+ stores or to alter cytosolic pH. CONCLUSION: LPS combined with serum factors binds to CD14 on the surface of AM, and PKC is an important signaling kinase in the pathway utilized by LPS, resulting in enhanced TF expression; a pertussis toxin-sensitive G protein is involved in the signaling pathway utilized by LPS alone; and mobilization of Ca2+ does not have a role in the signal transduction pathway utilized by LPS nor does LPS affect cytosolic pH of AM.

Induction of procoagulant activity in virus infected bovine alveolar macrophages and the effect of lipopolysaccharide.

Three viruses known to be associated with the bovine respiratory disease complex were evaluated in vitro for potential impact upon the procoagulant activity (PCA) of bovine alveolar macrophages (bAM). Cultures of bAM were inoculated with bovine parainfluenza virus Type 3 (PI-3), cytopathic bovine viral diarrhea virus (cpBVDV), non-cytopathic BVDV (ncpBVDV), or bovine herpes virus Type 1 (BHV-1) and incubated for several time periods (24, 48, 72, 96 h). BAM were then exposed to E. coli lipopolysaccharide (LPS), or LPS with bovine serum. The amount of PCA expressed was quantified using a chromogenic assay. Viral inoculation increased bAM expression of PCA (P < 0.01). The increase in PCA expression was larger at higher rates of viral inoculation (P < 0.01). LPS enhanced PCA expression by bAM at low rates of viral inoculation (P < 0.01). The effect of LPS-serum treatment was greater than the LPS alone (P < 0.01). At high rates of viral inoculation, LPS had no enhancing effect on PCA expression. The effect of LPS on virus inoculated bAM varied with virus type, rate of inoculation, and duration of virus exposure (P < 0.01). The results suggest that these four viruses initiate the production of PCA by bAM independently of LPS. In the field situation, an initial viral infection may induce fibrin deposition in the pulmonary alveoli prior to the establishment of a secondary gram negative bacterial infection.

Nitric oxide production and expression of inducible nitric oxide synthase by bovine alveolar macrophages.

Alveolar macrophages play a central role in host defense in the lower respiratory tract. Production of the reactive intermediate nitric oxide (NO), via expression of inducible nitric oxide synthase (iNOS) is an important microbicidal effector mechanism possessed by macrophages. In this study, cytokine regulation of NO production by bovine alveolar macrophages (bAM) was evaluated. Bovine alveolar macrophages were exposed to one or more of the following: recombinant human (rh) and recombinant bovine (rb) IFN gamma, rh- and rbIL-1 beta, rbGM-CSF, rhTNF alpha, rhIL-4, endotoxin (LPS), fetal bovine serum (FBS), mitogen-stimulated bovine splenic supernatant (SS), and purified human TGF beta-1. LPS alone, or in combination with SS, rbIFN gamma, or rbIL-1 beta stimulated production of NO in a time and dose dependent fashion. Recombinant bovine IFN gamma, rbIL-1 beta, and rhTNF alpha in combination produced maximal stimulation which was not further enhanced by LPS. Recombinant human IFN gamma, rhIL-1 beta, and rbGM-CSF had minimal effect either as single stimuli, or in combination with LPS, rbIFN gamma, rbIL-1 beta, or rhTNF alpha. Nitric oxide production was inhibited by rhIL-4, and the L-arginine analogue antagonists of iNOS, N-G-monomethyl-L-arginine (NGMMA) and aminoguanidine (AG). Purified human TGF beta-1 did not inhibit NO production. Messenger RNA for iNOS was maximally expressed by 8 h and remained detectable for at least 48 h. Expression of iNOS mRNA induced by cytokines and LPS varied with strength of the stimulus as determined by nitrite production in culture supernatant.

Purification of lipopolysaccharide-binding protein from bovine serum.

Lipopolysaccharide-binding protein (LBP) plays a central role in presentation of bacterial-derived lipopolysaccharide (LPS; endotoxin) to leukocytes such as macrophages and neutrophils. Interaction of LBP with LPS is significant because LBP-LPS complexes promote activation of leukocytes and the immune system, which results in enhanced secretion of a spectrum of proinflammatory cytokines. An improved, simplified method was used to purify bovine LBP from serum. Methodology consisted of ion-exchange chromatography using Bio-Rex 70 resin, followed by gel-filtration chromatography (Sephacryl S-200 resin) of a selected ion-exchange fraction (0.22-0.50 M NaCl). Densitometric scans on silver-stained polyacrylamide gels of chromatographically-derived proteins indicated up to 88.7% purity of the resultant 64kD protein (bovine LBP) in the cleanest fractions. The isoelectric point of bovine LBP was determined to be 6.8. Identity of the protein was substantiated by western-blot analysis, and by N-terminus amino acid sequence analysis with favorable comparison to published sequence data from rabbit, human, and murine LBP Identity was corroborated by use of purified bovine LBP in bioassays which demonstrated enhanced tissue factor expression of LPS (1 ng ml(-1)-stimulated bovine alveolar macrophages. Tissue factor expression was inhibitable in these assays using anti-CD14 monoclonal antibodies, which is also consistent with LBP-mediated activation of cells. When bovine LBP was heated at 56 degrees C for 30 min, the biological activity was reduced by 50% in the macrophage-based bioassays. Biological activity of bovine LBP was completely destroyed by heating at 62 degrees C for 30 min, which compared favorably with data resulting from use of fetal bovine serum.

Attempt to pharmacologically modulate procoagulant activity of lipopolysaccharide-stimulated adherent bovine alveolar macrophages.

OBJECTIVE: To investigate the effects of anti-inflammatory drugs on lipopolysaccharide-induced procoagulant activity of bovine alveolar macrophages. DESIGN: Procoagulant activity was induced in bovine alveolar macrophages from 4 healthy Holstein calves aged 6 to 16 weeks by incubation with lipopolysaccharide. 3 anti-inflammatory drugs were used at 4 concentrations and 3 times to pretreat the alveolar macrophages. Results were analyzed to determine whether drug, concentration, or exposure period had a significant (P > 0.05) effect. PROCEDURE: Bovine alveolar macrophages, harvested by volume-controlled bronchoalveolar lavage, were pretreated for 30, 60, or 120 minutes with an anti-inflammatory compound (dexamethasone, flunixin meglumine, or phenylbutazone) at several concentrations ( 0, 1, 10, and 100 microM). Bovine alveolar macrophages were exposed to lipopolysaccharide (Escherichia coli O55:B5) in the presence and absence of fetal bovine serum for 4 hours. Procoagulant activity was measured, using a chromogenic assay. RESULTS: None of the drugs was associated with a modification of procoagulant activity expression. CONCLUSION: Use of these 3 anti-inflammatory drugs is unlikely to modify the extent of the fibrinous reaction commonly observed in cases of acute bovine respiratory tract disease complex. CLINICAL RELEVANCE: The alveolar macrophage has a key role in fibrin production. Assuming in vivo events mimic the in vitro model, is appears unlikely that administration of anti-inflammatory drugs will reduce the procoagulant activity of the bovine alveolar macrophages and the directly associated pulmonary fibrosis.

Bacterial lipopolysaccharide-stimulated nitric oxide generation is unrelated to concurrent cytotoxicity of bovine alveolar macrophages.

Nitric Oxide (NO) is a reactive metabolite produced by stimulated macrophages, and it has been demonstrated to exert cytotoxic actions on a number of microbes, parasites, and tumor cells. In addition, NO has been reported to have an autotoxic effect on murine macrophages, its site of synthesis. We have investigated the relationship of NO generation to cytotoxicity of bovine alveolar macrophages (AM) in vitro, and have also assessed the effects of several modulators of cellular function on this relationship. NO was generated in cultures of AM using sodium nitroprusside (SNP) and measured as [nitrite]. Cellular viability of AM reflected a strong, negative correlation with the concentration of NO/nitrite in supernatants (r = -0.987). Supernatants with nitrite concentrations in excess of 30 microMs were correlated with cytotoxicity. AM stimulated with the potent combination of endotoxin (Lipopolysaccharide, LPS; 10 ng/ml) and recombinant bovine IFN gamma (100 U/ml) also exhibited cytotoxicity over a 48-hour incubation period, and cells deteriorated to an average viability of 72.3% as compared to unstimulated control macrophages. In some cases the viability of macrophages was much lower. Even though LPS-mediated cytotoxicity occurred, the [nitrite] produced in supernatants during the 48-hour period (12.23 microMs) was well below the minimum concentration of SNP-generated NO required to induce cytotoxicity to macrophages. N(G)-monomethyl-L-arginine (N(G)MMA, 2 mM) is a competitive inhibitor of NO synthesis and was found to reduce nitrite concentrations from 12.23 microMs to 1.56 microMs in supernatants of LPS-stimulated AM, but this reduction did not promote increased viability of AM. Other modulators of cellular function including phenylbutazone (PBZ, 100 microMs), flunixin meglumine (FM, 100 microMs) and interleukin-4 (IL-4, 100 ng/ml) modestly inhibited synthesis of NO, but did not improve cellular viability. These results suggest that relatively high concentrations of exogenously-generated NO are toxic to AM in vitro, but the quantity of endogenously-generated NO synthesized by LPS-stimulated bovine AM is usually below the threshold for toxicity. Cytotoxicity occurs independently of NO synthesis, and factors other than NO are apparently responsible for LPS-related cytotoxicity to bovine macrophages.

Analysis of the CD14 receptor associated with bovine alveolar macrophages.

Previous studies have suggested the existence of a bovine homolog of the membrane-associated CD14 receptor (mCD14) on macrophages, and functional similarity of bovine mCD14 receptor activity to that reported for other species. Bovine alveolar macrophages (bAM) reportedly possess two mRNA transcripts of 1.5 and 3.1 kb for CD14, rather than a single 1.5 kb transcript as reported for other species. The purpose of this study was to determine the molecular mass of the bovine CD14 receptor, and to determine if the two mRNA transcripts for bovine CD14 yield either a single or two different gene products. Culture supernatant from 125I-surface-labeled bAM was examined for the existence of bovine CD14 using SDS-PAGE and autoradiography. A single protein band of 49 kD was immunoprecipitated from the supernatant using anti-CD14 monoclonal antibodies (MAb). Macrophage-derived mRNA was subjected to hybrid-selection using a human CD14 cDNA probe immobilized on a nitrocellulose filter. The resultant, selected bovine mRNA was then utilized for in vitro translation, and protein of 38-40 kD was synthesized. This size is consistent with an unglycosylated CD14 receptor protein. Protein was also synthesized from total RNA by in vitro translation, and was immunoprecipitated with anti-CD14 monoclonal antibodies. A doublet-band of protein was seen at 38 kD using SDS-PAGE and autoradiography. Anti-CD14 antibodies were also used to inhibit serum- and LPS-dependent bovine macrophage activation as measured by tissue factor expression, which is compatible with the presence and function of CD14 receptors on macrophages. These results collectively demonstrate that a receptor consistent with CD14 is present on bovine macrophages, the form of the receptor released into supernatants is 49 kD, and that it functions as an LPS receptor on these cells.