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Latest Paper:
Bioorg Med Chem Lett. 2012 Apr 20;:
22578458
Lin Chu,
Helen M Armstrong,
Linda L Chang,
Amy F Cheng,
Lawrence Colwell,
Jisong Cui,
Jilly Evans,
Amy Galka,
Mark T Goulet,
Nancy Hayes,
Jane Lo,
John Menke,
Hyun O Ok,
Debra L Ondeyka,
Minal Patel,
Grace M Quaker,
Heather Sings,
Stephanie L Witkin,
Annie Zhao,
Feroze Ujjainwalla
Discovery and Preclinical Sciences, Merck Research Laboratories, Rahway, NJ 07065, USA.
A search for a suitable replacement for the central norbornyl scaffold presented in the recently disclosed novel FLAP inhibitors is herein described, as well as the SAR study performed on the endo and exo-aryl groups.
Department of Microbiology, The Chinese University of Hong Kong, The Prince of Wales Hospital, Shatin, New Territories, Hong Kong, ROC.
A total of 182 Salmonella enterica serotype Typhi isolated from three hospitals in Hong Kong from 1986 to 1992 were tested for their susceptibility to 21 antimicrobial agents. Four percent or less were resistant to chloramphenicol, ampicillin, some of the cephalosporins, nalidixic acid, tetracycline and trimethoprim and 6% to 1024 mg/l sulfamethoxazole. All were susceptible to the aminoglycosides and the 4-quinolones. Nineteen isolates were resistant to at least 1, and up to 9, antibiotics. Of 8 chloramphenicolor multiply-resistant isolates studied, only 3 could transfer their resistances while resistance of one could only be mobilized. Four of 5 ampicillin-resistant strains produced a beta-lactamase of pI 5.5. Antibiotic resistances were mediated by plasmids of 106, 116 or 221 kb of incompatibility groups H, I1 and K. Three resistant isolates did not harbour any plasmid. A total of 43 (24%) S. Typhi harboured plasmids ranging in size from 4.3 to 221 kb. Plasmids of 106 kb and 8.5 kb were found in 17 and 10 isolates, respectively. Restriction enzyme digestion of these two plasmids showed that each could be differentiated into 3 types. Of 89 isolates that were phage typed, 38% were untypable, while 17% and 12% were of phage types E1 and A, respectively, and the rest belonged to 17 other types.
J R Spencer,
S A Stern,
A F Cheng,
H A Weaver,
D C Reuter,
K Retherford,
A Lunsford,
J M Moore,
O Abramov,
R M C Lopes,
J E Perry,
L Kamp,
M Showalter,
K L Jessup,
F Marchis,
P M Schenk,
C Dumas
Jupiter's moon Io is known to host active volcanoes. In February and March 2007, the New Horizons spacecraft obtained a global snapshot of Io's volcanism. A 350-kilometer-high volcanic plume was seen to emanate from the Tvashtar volcano (62 degrees N, 122 degrees W), and its motion was observed. The plume's morphology and dynamics support nonballistic models of large Io plumes and also suggest that most visible plume particles condensed within the plume rather than being ejected from the source. In images taken in Jupiter eclipse, nonthermal visible-wavelength emission was seen from individual volcanoes near Io's sub-Jupiter and anti-Jupiter points. Near-infrared emission from the brightest volcanoes indicates minimum magma temperatures in the 1150- to 1335-kelvin range, consistent with basaltic composition.
K D Retherford,
J R Spencer,
S A Stern,
J Saur,
D F Strobel,
A J Steffl,
G R Gladstone,
H A Weaver,
A F Cheng,
J Wm Parker,
D C Slater,
M H Versteeg,
M W Davis,
F Bagenal,
H B Throop,
R M C Lopes,
D C Reuter,
A Lunsford,
S J Conard,
L A Young,
J M Moore
The New Horizons (NH) spacecraft observed Io's aurora in eclipse on four occasions during spring 2007. NH Alice ultraviolet spectroscopy and concurrent Hubble Space Telescope ultraviolet imaging in eclipse investigate the relative contribution of volcanoes to Io's atmosphere and its interaction with Jupiter's magnetosphere. Auroral brightness and morphology variations after eclipse ingress and egress reveal changes in the relative contribution of sublimation and volcanic sources to the atmosphere. Brightnesses viewed at different geometries are best explained by a dramatic difference between the dayside and nightside atmospheric density. Far-ultraviolet aurora morphology reveals the influence of plumes on Io's electrodynamic interaction with Jupiter's magnetosphere. Comparisons to detailed simulations of Io's aurora indicate that volcanoes supply 1 to 3% of the dayside atmosphere.
W M Grundy,
B J Buratti,
A F Cheng,
J P Emery,
A Lunsford,
W B McKinnon,
J M Moore,
S F Newman,
C B Olkin,
D C Reuter,
P M Schenk,
J R Spencer,
S A Stern,
H B Throop,
H A Weaver
The New Horizons spacecraft observed Jupiter's icy satellites Europa and Ganymede during its flyby in February and March 2007 at visible and infrared wavelengths. Infrared spectral images map H2O ice absorption and hydrated contaminants, bolstering the case for an exogenous source of Europa's "non-ice" surface material and filling large gaps in compositional maps of Ganymede's Jupiter-facing hemisphere. Visual wavelength images of Europa extend knowledge of its global pattern of arcuate troughs and show that its surface scatters light more isotropically than other icy satellites.
Mark R Showalter,
Andrew F Cheng,
Harold A Weaver,
S Alan Stern,
John R Spencer,
Henry B Throop,
Emma M Birath,
Debi Rose,
Jeffrey M Moore
The dusty jovian ring system must be replenished continuously from embedded source bodies. The New Horizons spacecraft has performed a comprehensive search for kilometer-sized moons within the system, which might have revealed the larger members of this population. No new moons were found, however, indicating a sharp cutoff in the population of jovian bodies smaller than 8-kilometer-radius Adrastea. However, the search revealed two families of clumps in the main ring: one close pair and one cluster of three to five. All orbit within a brighter ringlet just interior to Adrastea. Their properties are very different from those of the few other clumpy rings known; the origin and nonrandom distribution of these features remain unexplained, but resonant confinement by Metis may play a role.
G Randall Gladstone,
S Alan Stern,
David C Slater,
Maarten Versteeg,
Michael W Davis,
Kurt D Retherford,
Leslie A Young,
Andrew J Steffl,
Henry Throop,
Joel Wm Parker,
Harold A Weaver,
Andrew F Cheng,
Glenn S Orton,
John T Clarke,
Jonathan D Nichols
Observations of Jupiter's nightside airglow (nightglow) and aurora obtained during the flyby of the New Horizons spacecraft show an unexpected lack of ultraviolet nightglow emissions, in contrast to the case during the Voyager flybys in 1979. The flux and average energy of precipitating electrons generally decrease with increasing local time across the nightside, consistent with a possible source region along the dusk flank of Jupiter's magnetosphere. Visible emissions associated with the interaction of Jupiter and its satellite Io extend to a surprisingly high altitude, indicating localized low-energy electron precipitation. These results indicate that the interaction between Jupiter's upper atmosphere and near-space environment is variable and poorly understood; extensive observations of the day side are no guide to what goes on at night.
Kevin H Baines,
Amy A Simon-Miller,
Glenn S Orton,
Harold A Weaver,
Allen Lunsford,
Thomas W Momary,
John Spencer,
Andrew F Cheng,
Dennis C Reuter,
Donald E Jennings,
G R Gladstone,
Jeffrey Moore,
S Alan Stern,
Leslie A Young,
Henry Throop,
Padma Yanamandra-Fisher,
Brendan M Fisher,
Joseph Hora,
Michael E Ressler
Although lightning has been seen on other planets, including Jupiter, polar lightning has been known only on Earth. Optical observations from the New Horizons spacecraft have identified lightning at high latitudes above Jupiter up to 80 degrees N and 74 degrees S. Lightning rates and optical powers were similar at each pole, and the mean optical flux is comparable to that at nonpolar latitudes, which is consistent with the notion that internal heat is the main driver of convection. Both near-infrared and ground-based 5-micrometer thermal imagery reveal that cloud cover has thinned substantially since the 2000 Cassini flyby, particularly in the turbulent wake of the Great Red Spot and in the southern half of the equatorial region, demonstrating that vertical dynamical processes are time-varying on seasonal scales at mid- and low latitudes on Jupiter.
D C Reuter,
A A Simon-Miller,
A Lunsford,
K H Baines,
A F Cheng,
D E Jennings,
C B Olkin,
J R Spencer,
S A Stern,
H A Weaver,
L A Young
Several observations of Jupiter's atmosphere made by instruments on the New Horizons spacecraft have implications for the stability and dynamics of Jupiter's weather layer. Mesoscale waves, first seen by Voyager, have been observed at a spatial resolution of 11 to 45 kilometers. These waves have a 300-kilometer wavelength and phase velocities greater than the local zonal flow by 100 meters per second, much higher than predicted by models. Additionally, infrared spectral measurements over five successive Jupiter rotations at spatial resolutions of 200 to 140 kilometers have shown the development of transient ammonia ice clouds (lifetimes of 40 hours or less) in regions of strong atmospheric upwelling. Both of these phenomena serve as probes of atmospheric dynamics below the visible cloud tops.
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