Communications t o the Editor
3221EXAFS results also demonstrate that oxidative addition to form a six-coordinate Pt(1V)-DNA adduct with the retention of both ammines and chlorides does not occur. From the EXAFS spectra, no appreciable differences were detected at this stage in the platinum coordination spheres of the complexes formed by cis-and trans-DDP with DNA. This result, however, should not be taken to indicate that subtle differences do not exist.In conclusion, this work provides, for the first time, strong structural evidence against the possibility of distinct metalmetal bonding in the complexes of both cis-and trans-DDP with calf thymus DNA. The data are consistent with the presence of four Pt-N (or -0) bonds in a presumably square-planar Pt(I1) coordination sphere. Further stereochemical details from EXAFS study must await determination of interatomic distances other than those in the coordination shell using spectra of higher signal-to-noise ratio (in progress).(1) (a)
This work reports the use of single-shot spin echo sequences to achieve in vivo diffusion gas measurements and ultrafast imaging of human lungs, in vivo, with hyperpolarized 3 He at 0.1 T. The observed transverse relaxation time of 3 He lasted up to 10 s, which made it possible to use long Carr-Purcell-Meiboom-Gill echo trains. Preliminary NMR studies showed that the resolution of lung images acquired with hyperpolarized 3 He and single-shot sequences is limited to about 6 mm because of the diffusion of the gas in applied field gradients. Ultrafast images of human lungs in normal subjects, achieved in less than 0.4 s with the equivalent of only 130 mol of fully polarized 3 He, are presented. Comparison with other studies shows that there is no SNR penalty by using low fields in the hyperpolarized case. Advantage was taken of the self diffusion-weighting of the rapid acquisition with relaxation enhancement (RARE) sequence to acquire apparent diffusion coefficient (ADC) images of the lungs. Time scales of seconds could be explored for the first time because there is no hindrance from T * 2 as with the usual approaches. At 0.1 T, 180°RF pulses can be repeated every 10 ms without exceeding specific absorption rate limits, which would not be the case for higher fields. Moreover, at low field, susceptibility-induced phenomena are expected to be milder. This supports the idea that low-field imagers can be used for hyperpolarized noble gas MRI of lungs and may be preferred for ADC measurements. Magn Reson Med 47:75-81, 2002.
In rat patellar cartilage, T2 mapping permits detection of slight or severe proteoglycan depletion and concurrent changes of extracellular matrix when age-matched samples are compared.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.