Biomedical subjects

S Kauffman

Publications and source records attributed to S Kauffman.

29 records · Page 2Linked to original sources

PubMed1978

A prospective study of sudden death in "high-risk" bundle-branch block.

We prospectively followed 257 patients with bifascicular and trifascicular conduction-system disease and intact atrioventricular conduction who had undergone His-bundle studies. Forty-seven per cent had associated coronary-artery disease, and 23 per cent primary conduction-system disease. His-ventricular interval was moderately prolonged in 43 per cent and markedly prolonged in 12 per cent. During an average follow-up period of 25 months 50 patients died. However, death was sudden in only 27, and 17 of the sudden deaths were not due to bradyarrhythias. Actuarial analysis showed an overall mortality rate (mean +/- S.E.) of 19 +/- 2.6 per cent at two years, mortality from sudden death being 10 +/- 2.6 per cent. Permanent heart block occurred in 12. No clinical symptoms (including syncope), electrocardiographic findings, electrophysiologic data or their combination identified patients at high risk of sudden death. Sudden death due to bradyarrhythmia is uncommon in patients with bundle-branch block and intact atrioventricular conduction. Therefore, routine prophylactic use of permanent pacemakers in all such patients is inappropriate. Pacemaker implantation should be reserved for those with documented symptomatic bradyarrhythmias.

Adult↗

PubMed1978

Survival in patients with intraventricular conduction defects.

All 42,000 electrocardiograms taken at the University of Oregon Health Sciences Center from 1969 through 1971 were reviewed; 325 patients (0.77%) had left bundle-branch block (LBBB) or right bundle-branch block (RBBB) with axis deviation (AD). In December 1974, 90% were contacted or found to be dead. The five-year survival rate (actuarial technique) (mean +/- SE) was 45.5 +/- 2.9%. It was significantly worse than that of age- and sex-matched "controls." In most patients the cause of death could not be determined. Survival of 164 LBBB patients (40.7 +/- 4.1%) at five years was not significantly worse than that of 161 RBBB and AD patients (49.5 +/- 4.2%). Those with syncope did no worse in terms of survival than did those without. The five-year survival in coronary artery disease patients was 33.7 +/- 4.4%, in those with primary conduction system disease (20% of patients), it was 50.6 +/- 6.6%. It will be necessary to know the causes of death and of syncope in conduction disease patients before it can be determined whether or not pacemakers can prevent either.

Adult↗

PubMed1975

Control circuits for determination and transdetermination: interpreting positional information in a binary epigenetic code.

Positional information in an embryo requires interpretation to guide spatially ordered differentiation. Evidence, from dtermination and transdetermination among imaginal disc derivatives in Drosophila, suggests the interpretative commitment, or determination, is carried by entities possissing only two alternate states each. This hypothesis correctly predicts pairs of classes of mutants affecting complementary subsets of imaginal discs. Four such complementary pairs define four boundaries separating the various imaginal discs on the fate map of the egg. Crossing any boundary corresponds to a change in state of the associated determination circuit. Using these boundaries, the model makes 43 predictions about relative transdetermination frequencies. Thirty-four appear correct. This has an a priori probability of less than 10- minus 4. False predictions appear to reflect incompleteness in the theory. The four boundaries on the fate map presumably correspond to threshold levels of spatial gradients constituting positional information; on one side of a threshold one circuit state occurs, on the other, the second state. The last four cleavage divisions in Drosophila melanogaster occur as four mitotic waves with geometries similar to the four boundaries. Disc determination happens at about this time. These waves may be, or reflect, the signalling system carrying positional information. Focus on the interpretive machinery, the determination circuits, suggests two slightly new concepts: (1 the set of possible combinations of states of determination circuits constitutes an epigenetic code, thus raising familiar coding questions concerning redundancy or nonsense words; (2) each circuit may respond to its own gradient or positional signal distributed in two or three dimensions.

Animals↗

PubMed1975