The structure of antibiotic G-52, a new aminocyclitol-aminoglycoside antibiotic produced by Micromonospora zionensis

Antibiotic G-52, a new aminocyclitol-aminoglycoside antibiotic produced in the fermentation of Micromonospora zionensis, has been shown to be 6'-N-methylsisomicin on the basis of its spectral characteristics. This assignment was confirmed by synthesis of the antibiotic from sisomicin.     

Dissection of the aorta complicating intra-aortic balloon counterpulsation

A 61-year-old man with recent myocardial infarction complicated by a ventricular aneurysm and recurrent ventricular tachycardia underwent intra-aortic balloon counterpulsation prior to angiography and left ventricular aneurysmectomy. A dissecting aneurysm of the descending aorta adjacent to the position of the balloon catheter was found at autopsy. No intimal tear or cystic medial degeneration of the aorta was present to account for the dissection. The authors suggest that lateral and shearing forces generated by inflation of the balloon could result in dissection of the aorta.