The generality of architectural isomerism in designer inclusion frameworks

We describe herein new structural isomers of a lamellar host system based on organodisulfonate "pillars" that connect opposing hydrogen-bonded sheets, consisting of topologically complementary guanidinium (G) ions and sulfonate (S) groups, to generate inclusion cavities between the sheets. These new isomers-zigzag brick, double brick, V-brick, and crisscross bilayer-expand significantly on our earlier report of architectural isomerism displayed by the discrete bilayer and simple brick forms. We demonstrate here that the discrete bilayer-simple brick isomerism, which was limited to several host-guest combinations based on the G(2)(4,4'-biphenyldisulfonate) host and one pair of compounds based on the G(2)(2,6-naphthalenedisulfonate), can be generalized to other organodisulfonate pillars. Furthermore, in many cases the selectivity toward the different framework isomers reflects a rather systematic templating role of the guest molecules and host-guest recognition during assembly of the lattice. We also describe a convenient approach to identifying and classifying the innumerable possible host architectures based upon the pillar projection topologies for the GS sheets and the intersheet connectivities. The discovery of these new architectures reveals a structural versatility for this class of materials that exceeds initial expectations and observations. Each topology produces different connectivities between the sheets in the third dimension that endows each framework isomer with uniquely shaped and sized inclusion cavities, enabling this host system to conform readily to different guests. The unlimited number of architectures available, combined with the inherent conformational softness and structural tunability of these host lattices, suggests a near universality for the GS system with respect to guest inclusion.

Postinfarctional ventricular septal rupture. Clinical approach and surgical results

This study represents an analysis of 13 cases of ruptured interventricular septum occurring as a complication of myocardial infarction. The cases considered appeared to divide themselves into two groups. One group survived the septal rupture for weeks or months and underwent surgery in the chronic stage. The patients in the other group were diagnosed and underwent surgery in the acute stage because of clinical indications of a rapidly deteriorating situation. There were four serious complications resulting from extensive cardiac catheterization and angiographic procedures. Those patients who were diagnosed using bedside balloon-directed catheterization techniques had no serious complications. The data indicate that: (1) the diagnostic approach should be executed quickly and by simple methods; (2) it is possible to operate successfully upon these patients in the acute phase of their disease; and (3) because of the unpredictable course and rapid deterioration, these alternatives should be strongly considered.

Aortic stenosis, angina, and coronary artery disease. Interrelations

Sixty-nine patients over age 35 with severe valvular aortic stenosis were investigated for concomitant coronary artery disease. Forty (57.9%) had clinical angina pectoris. Sixteen (23.2%) had significant coronary occlusive disease by arteriography. Of those with angina, 13 patients (32.5) had significant coronary arterial obstruction, while in the pain-free group only (10.3%) had occlusive coronary disease. It is concluded that patients with severe aortic stenosis who are free of angina have only a small, but definite, chance of having significant coronary disease.

Inability of the submaximal treadmill stress test to predict the location of coronary disease

Two hundred patients had submaximal treadmill stress tests (STSTs) and selective coronary arteriography performed within 2 months of each other. An attempt was made to assess the predictability of disease isolated to any given coronary vessel by performance on the treadmill. This was not possible for disease isolated to the right coronary, the left anterior descending, the circumflex branch of the left coronary, or a combination of right coronary and circumflex arteries. Eleven patients had disease in the left main coronary artery; all had associated disease of some other branch as well. One of these patients had a negative submaximal treadmill stress test but was unable to reach 90% of his maximum predicted heart rate. The remaining 10 patients had positive STSTs. Patients with 26-50% narrowing of any branch had treadmill results similar to those with 51-75% narrowing. There was a large number of patients with single-vessel disease in the study and most of the negative STSTs occurred in this group. Nevertheless, within this group no one vessel gave a higher incidence of positive STSTs than any other. It is concluded that (1) a positive STST is more likely to be associated with increased severity and extent of coronary artery disease; (2) a negative STST is more likely to be found in disease limited to a single vessel; and (3) within the latter group, the STST is of no value in predicting the specific coronary artery involved.