Über die Konstitution der Visnagane und Khellactone ausAmmi visnaga L.

Summary The visnagans fromAmmi visnaga L. and the stereoisomeric khellactones and methyl-khellactones derived from them were transformed into seselin and umbelli-ferone-8-aldehyde. These transformations and other degradations lead to revised formulas for these natural compounds.     

The suppression of star formation by powerful active galactic nuclei

The old, red stars that constitute the bulges of galaxies, and the massive black holes at their centres, are the relics of a period in cosmic history when galaxies formed stars at remarkable rates and active galactic nuclei (AGN) shone brightly as a result of accretion onto black holes. It is widely suspected, but unproved, that the tight correlation between the mass of the black hole and the mass of the stellar bulge results from the AGN quenching the surrounding star formation as it approaches its peak luminosity. X-rays trace emission from AGN unambiguously, whereas powerful star-forming galaxies are usually dust-obscured and are brightest at infrared and submillimetre wavelengths. Here we report submillimetre and X-ray observations that show that rapid star formation was common in the host galaxies of AGN when the Universe was 2-6 billion years old, but that the most vigorous star formation is not observed around black holes above an X-ray luminosity of 10(44) ergs per second. This suppression of star formation in the host galaxy of a powerful AGN is a key prediction of models in which the AGN drives an outflow, expelling the interstellar medium of its host and transforming the galaxy's properties in a brief period of cosmic time.     

Patterning the zebrafish axial skeleton requires early chordin function

Members of the bone morphogenetic protein (BMP) family actively promote ventral cell fates, such as epidermis and blood, in the vertebrate gastrula. More dorsally, the organizer region counteracts BMP signalling through secretion of BMP-binding antagonists chordin and noggin, allowing dorsally derived tissues such as neurectoderm and somitic muscle to develop. BMPs also function in skeletal development and regeneration of bone following injury. Noggin antagonism is thought to prevent osteogenesis at sites of joint formation, whereas chordin has not yet been implicated in skeletogenesis. Analyses of zebrafish mutants have confirmed the action of chordin (chd) in opposing ventralizing signals at gastrulation. Some ventralized mutants recover and develop into fertile adults, thereby revealing a requirement for chd function for the later processes of fin and caudal skeletal patterning. We observe in mutants the misexpression of genes encoding BMPs and putative downstream genes, and ectopic sclerotomal cells. Through injections of chd mRNA into the early embryo, we restored wild-type gene expression patterns, and the resultant fish, although genotypically mutant, developed normal axial skeletons and fins. Our results demonstrate that chordin function during gastrulation is important for the correct morphogenesis of the adult zebrafish skeleton.     

Prévention de l'œdème aigu expérimental du poumon par un antihistaminique de synthèse dérivé de la thiodiphénylamine

Summary N-dimethylamino-2-propyl-1-phenothiazine (3277 R.P.) has been shown to possess an antihistamine and anti-anaphylactic activity that is unequaled up to now.Hypodermic preventive injections regularly protect the rabbit against acute pulmonary dema provoked by epinephrine. An intravenous injection of this substance made 3 to 4 minutes after an intravenous injection of epinephrine, that is at the time an acute pulmonary dema seems to begin, is able to prevent fatal consequences.The hypertensive action of adrenaline, and the resulting dilatation of the heart is not prevented by the phenothiazine derivative.The antihistamine substance seems to exercise an effect on capillary permeability when preventing acute pulmonary dema.

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