Clinical characteristics and thrombolytic outcomes of infective endocarditis-associated stroke.

OBJECTIVE: Our aim was to describe the clinical features of infective endocarditis (IE) in the acute stroke setting and outcomes following thrombolytic therapy. METHODS: This is a single-center, retrospective, descriptive case series of IE-related stroke (IES). Infective endocarditis diagnosis was based on the modified Duke criteria. RESULTS: From 2001 to 2007, 18 patients with acute stroke had definite or possible IE. Presenting stroke subtypes were: 11 ischemic stroke; 2 intracerebral hemorrhage; and 5 with a combination of ischemia and subarachnoid hemorrhage. On presentation, 6 had objective fever and 5 had subjective fever, 8 had heart murmur, and 3 had classic IE stigmata. The most common laboratory abnormalities were leukocytosis (n = 11) and anemia (n = 10). Sixteen patients had valvular vegetations on echocardiogram; 6 of 8 patients had vegetations visualized on transesophageal echocardiogram that were not detected by transthoracic echocardiogram. Two of the 3 patients with valve replacements had vegetations only on their native valves. Of 11 patients with pure ischemic stroke, 4 received thrombolytics and had hemorrhagic conversion. Overall mortality of IES was 56% (10 of 18). Mortality in pure ischemic IES patients was 29% (2 of 7, median National Institute of Health Stroke Scale [NIHSS] 13) in those not receiving thrombolytics and 75% (3 of 4, median NIHSS 14) in those receiving thrombolytics. CONCLUSIONS: Though diagnosis of IE in the acute stroke setting is difficult, features of the history, examination, and laboratory data may raise concern for IE. In this case series, thrombolytics in patients with IE-associated stroke were associated with very poor outcomes.

Cucurbit[6]uril pseudorotaxanes: distinctive gas-phase dissociation and reactivity.

Cucurbit[6]uril forms a doubly charged complex with 1,4-butanediammonium cation that is observed using electrospray ionization Fourier transform mass spectrometry. Such 1:1 complexes are not observed for the smaller cucurbit[5]uril, which forms a 2:1 ammonium:cucurbituril complex instead. The 1:1 complex with cucurbit[6]uril is difficult to fragment via collisional activation; when it does fragment, both breakup of the cucurbituril cage and loss of the amine are observed. Further, the complex reacts with tert-butylamine via slow adduction. In contrast, nonrotaxane analogues (such as doubly charged 2:1 complexes of either protonated 1,4-butanediamine or protonated ethylenediamine with cucurbit[6]uril) fragment via easy loss of the intact amine upon collisional activation and react with tert-butylamine via rapid displacement of the original amine. On the basis of stoichiometry, fragmentation behavior, and reactivity, we conclude that the doubly charged complex of cucurbit[6]uril with 1,4-butanediammonium is a gas-phase pseudorotaxane.