N-substituted 2-aminoimidazole inhibitors of MRSA biofilm formation accessed through direct 1,3-bis(tert-butoxycarbonyl)guanidine cyclization.

Antibiotic resistance is a significant problem and is compounded by the ability of many pathogenic bacteria to form biofilms. A library of N-substituted derivatives of a previously reported 2-aminoimidazole/triazole (2-AIT) biofilm modulator was constructed via α-bromoketone cyclization with 1,3-bis(tert-butoxycarbonyl)guanidine, followed by selective substitution. Several compounds exhibited the ability to inhibit biofilm formation by three strong biofilm forming strains of methicillin resistant Staphylococcus aureus (MRSA). Additionally, a number of members of this library exhibited synergistic activity with oxacillin against planktonic MRSA. Compounds with this type of dual activity have the potential to be used as adjuvants with conventional antibiotics.

Detection and Quantification of Gaseous and Particulate Fukushima Fission Products at Orangeburg, South Carolina.

ABSTRACT: Large amounts of fission products were released from the Fukushima nuclear accident after a devastating earthquake and subsequent tsunami hit the northeast coast of Japan on 11 March 2011. The radioactive mass was sent high into the atmosphere by hydrogen explosions and fires in the reactor buildings at Fukushima Daiichi Nuclear Power Plant and spread all over the world. A relatively complete detection of both gaseous and particulate fission products was conducted during 15 March and 30 May 2011 at Orangeburg, South Carolina, located along the southeast coast of the United States, 11,000 km from the accident site. The histograms of gaseous and particulate radionuclides were obtained, and the major radioactivity plateaus were found between 18 March and 7 April 2011. The maximum levels of particulate and gaseous 131I were 1.0 ± 0.1 and 5.0 ± 0.4 mBq m-3, respectively. The maximum radioactivities of 134Cs and 137Cs were 10 times less than that of the particulate 131I. The average activity ratio of 134Cs to 137Cs was determined as 0.98 ± 0.26 throughout the observation. It was found that the plateaus and spikes in the histogram curves corresponded to the nuclear release events at Fukushima Daiichi. The arrival times of the particulate and gaseous nuclear fallout were determined to be 8 and 10 d, respectively. The deposition rates of gaseous and particulate iodine and the mass transfer between the two phases were discussed based on the radioactivity ratios of the fission products. By comparing with the radionuclide effluent concentrations issued in NRC 10 CFR 20, it was concluded that the Fukushima fallout presented negligible radiation risk to the public at Orangeburg as well as in the southeastern coastal region of the U.S.